WATER DISCHARGE MECHANISM WITH DISENGAGEMENT SECTION

Abstract

 The present invention relates to a water discharge mechanism (1) of a toy water gun (100), comprising a cylinder unit (2) with a filling inlet (3) for receiving water and a nozzle outlet (4) for discharging water; a piston (5) configured to perform a piston stroke in the cylinder unit (2), wherein the piston stroke extends between a filled position (P1) and a discharged position (P2); an energy storing element (6), particularly a spring element, configured to apply a discharge force on the piston (5) acting towards the discharged position (P2); and a driving gear (7) with an engagement section (8), particularly a toothed section, and a disengagement section (9), particularly a toothless section; wherein the engagement section (8) is configured to engage with the piston (5) for moving the piston (5) against the discharge force into the filled position (P1); wherein the disengagement section (9) is configured to disengage the driving gear (7) and the piston (5). The invention further relates to a toy water gun and to a method for discharging water from a toy water gun.

Description

Technical Area

[0001] The present invention relates to a water discharge mechanism of a toy water gun and to a toy water gun for discharging water, and to a method for discharging water from a water toy gun.

Background Art

[0002] Toy water guns are well known in the prior art. For example, European Patent EP 3 901 558 B1 discloses a water gun for shooting short bursts of water providing the impression of water bullets. Another toy water gun is disclosed in EP 3 992 568 A1, which is directed at a toy water gun actuation mechanism. In the generic prior art, toy water guns tend to have a couple of drawbacks. For example, toy water guns require many components to interact in order to discharge water.

Summary of the Invention

[0003] The problem to be solved by the present invention is to improve the prior art. For example, the present invention aims to provide a water discharge mechanism, which is capable of discharging pressurized water while at the same time being space and weight saving and reliable. Further, the present invention exemplarily aims at a method for discharging reproducible bursts of water.

[0004] The problem is solved by a water discharge mechanism, a toy water gun, and a method for discharging water according to the invention as defined by the independent claims. Embodiments thereof are claimed by the dependent claims.

[0005] The invention relates to a water discharge mechanism of a toy water gun. Toy water guns may be used during leisure time activity. They may discharge bursts of water providing the impression of water bullets. The water discharge mechanism may be the mechanism responsible for discharging water out of the toy water gun once a trigger of the toy water gun is activated.

[0006] The water discharge mechanism comprises a cylinder unit with a filling inlet for receiving water and a nozzle outlet for discharging water. The cylinder unit may comprise a cylinder portion and a distinct discharge portion. The cylinder unit may be referred to as cylinder. The cylinder may define a volume of one burst of water. The nozzle outlet may be an opening at a front side of the cylinder while the filling inlet may be an opening at a radial outer side of the cylinder, particularly a radial outer side facing lateral, e.g. orthogonal to a shot axis. Both openings may be arranged at a front portion of the cylinder. Within the filling inlet and/or the nozzle outlet, there may be a valve. The or each valve, e.g. check valves, may ensure that water flows through the respective opening in one direction only and that no air is sucked in. The valve of the filling inlet may allow an inflow of water into the cylinder once the pressure inside the cylinder is below the pressure outside the filling inlet. The check valve of the nozzle outlet may allow an outflow of water out of the cylinder once the pressure inside the cylinder is above the pressure outside the nozzle outlet. The nozzle outlet may have an inner diameter with a varying cross sectional area so that the characteristics of the outflow are controlled, e.g. to provide a sharp burst of water. The outlet of the nozzle may have a diameter of 1.5 mm to 3.5 mm. The filling inlet may communicate with a water tank which supplies water to the cylinder through a charging fluid line.

[0007] The water discharge mechanism further comprises a piston configured to perform a piston stroke in the cylinder unit, wherein the piston stroke extends from a filled position to a discharged position. The piston may reciprocate in the cylinder for performing a filling of the cylinder with water and a discharging of water from the cylinder, i.e. a shooting of a burst of water. The piston may comprise a piston rack, a piston rod, and a piston top. The piston rack may engage, e.g. mechanically mesh, such as a form fit or a frictional force connection, with a driving gear, which is described further below. The piston rod may connect the piston rack with the piston top. The piston top may form a water working surface facing the nozzle outlet and being configured to act on water within the cylinder. The piston, particularly the piston top, may include a sealing providing a sealed reciprocating movement of the piston within the cylinder. The filled position may be reached when the piston is positioned at an end position of the cylinder facing away from the nozzle outlet. The discharged position may be reached when the piston is positioned at the end of the cylinder facing the nozzle outlet. The piston stroke extending from the filled position to the discharged position may be referred to as discharging stroke, while the stroke extending from the discharged position to the filled position may be referred to as filling stroke. The discharging stroke together with the filling stroke may form one cylinder cycle. One stroke may extend over a length of 35 mm to 55 mm, particularly 45 mm. When the piston performs the filling stroke, water may be sucked from the water tank into the cylinder. During the filling stroke, the check valve within the filling inlet may be open. Once the piston reaches the filled position, the check valve in the filling inlet may close mechanically as a pressure equilibrium between the cylinder and the charging fluid line may be established. When the piston performs the discharging stroke, water may be pushed out of the cylinder through the nozzle outlet. During the discharging stroke, a check valve within the nozzle outlet may be open. Once the piston reaches the discharged position, the check valve in the nozzle outlet may close mechanically as a pressure equilibrium between the cylinder and the surrounding may be established. The closing may be assisted by a rubber ball being pre-tensioned into the closed position. The pretension is to be large enough to close the nozzle outlet and seal it in an air-tight manner. The filling stroke may evoke a suction of water into the cylinder. For an efficient suction, a fluid path from the water tank via the charging fluid line through the filling inlet into the cylinder may be hermetically sealed for ensuring an efficient fluid exchange between the water tank and the cylinder.

[0008] The water discharge mechanism further comprises an energy storing element, particularly a spring element, configured to apply a discharge force on the piston acting towards the discharged position. The energy storing element may be an elastically deformable part, such as a spring element, e.g. a coil spring. The energy storing element may act on the piston, thereby applying the discharge force, for moving the piston from the filled position to the discharged position, thereby discharging water through the nozzle outlet. The amount of energy stored within the energy storing element may be predetermined and adjusted to the dimensions of the piston and the cylinder. The energy stored within the energy storing element may be chosen to be sufficiently high to move the piston sufficiently fast from the filled position to the discharged position to discharge the water within the cylinder in a sufficiently short amount of time, such as below 1.00 seconds, particularly between 0.02 to 0.30 seconds. The energy stored may be chosen to provide a discharge force between 30 N and 70 N, particularly 40 N, to act on the piston. When the piston is released, the energy storing element may still store10 N to 50 N, particularly 20 N. The higher the energy stored within the energy storing element, the faster the discharging stroke of the piston and the higher the velocity of the burst. The lower the energy stored within the energy storing element, the better the coherence of the discharged burst. Therefore, a compromise may be made between high and low energy stored. Furthermore, the design of the energy storing element may take into account the relationship between the initial and the final force of the energy storing element, e.g. the forces when the energy storing element is compressed and when it is released. In order to ensure the highest possible and uniform velocity of a discharged burst, a low spring rate, e.g. 40 N to 20 N, may be provided. This means that in the filled position, the energy acting on the piston may be twice as much as in the discharged position. This is surprisingly low compared to conventional energy storing elements. Thus, the difference between initial and final force may be quite small. The energy storing element may have properties, such as material properties and dimensions, ensuring a constant amount of energy for every discharging stroke over an entire service life of the toy water gun. Accordingly, the energy storing element may be of dimensions, for example length, diameter, wire diameter and material thickness, which provide a sufficient robustness and reliability over the entire service life of the toy water gun. It was found that a particularly long spring element may solve the task of a constant amount of energy for every discharging stroke over an entire service live in a reliable manner.

[0009] The water discharge mechanism further comprises a driving gear with an engagement section, particularly a toothed section, and a disengagement section, particularly a toothless section. A circumferential length of the engagement section may be one third of a circumferential length. The driving gear may be a gear wheel which is driven by an electric motor. Between an output shaft of the electric motor and the driving gear, there may be a predetermined number of gears for adjusting torque, rotation, and angles according to the needs of the driving gear and the piston. The gears may provide a constant gear ratio adjusted to a desired movement of the piston. Alternatively, the gears may provide a variable gear ratio for compensating higher spring forces. The driving gear may rotate around its center. The engagement section may be a circumferential section of the driving gear which is configured to mesh with a compatible part of the piston, particularly the rack of the piston. The engagement section may be a toothed section wherein the teeth have tooth flanks which are shaped in order to provide an optimal transmission of the torque of the driving wheel to the force of the piston. The disengagement section may be a circumferential section of the driving gear having a shape rendering it impossible to mesh with the piston, particularly the rack of the piston. Once the driving gear rotates, the engagement section and the disengagement section alternate at a given position.

[0010] The engagement section is configured to engage with the piston for moving the piston against the discharge force applied by the energy storing element into the filled position, thereby filling the cylinder via suctioning with water entering through the filling inlet. The engaging between the engagement section and the piston may be realized by a meshing of teeth. The length of the engagement section, i.e. the circumferential length along the driving gear, may be chosen to be sufficiently high to move the piston from one end within the cylinder, e.g. the discharged position, to the other end within the cylinder, e.g. the filled position. The engagement section and the piston may realize a linear actuator of the rack-and-pinion type in order to convert the rotational motion of the driving gear into a linear motion of the piston.

[0011] The disengagement section is configured to disengage the driving gear and the piston, thereby allowing a discharging of water in the cylinder as the discharge force acts on the piston in the direction of the discharged position. The engagement section and the piston may realize a linear actuator of the rack-and-pinion type (see above) to move the piston from the discharged position to the filled position during the filling stroke. When the piston performs the discharging stroke and moves in the other direction from the filled position to the discharged position, the piston shall not transmit its linear motion onto the driving gear. Accordingly, the disengagement section realizes a free movement between the piston and the driving gear, i.e. a disengagement, of the piston during the discharging stroke. A length of the disengagement section, i.e. the circumferential length along the driving gear, may be chosen to be sufficiently high for the piston to perform the discharging stroke while the disengagement section is facing to the piston resulting in a disengagement of the piston and the driving gear. The movement of the piston from the filled position to the discharged position is determined or at least influenced by the discharge force applied by the energy storing element. The discharge force and the length of the disengagement section may therefore be adapted to interact in such a way that the discharging stroke is entirely performed while the driving gear is disengaged with the piston. The driving gear's rotation may be interrupted by a control unit (see further below) to enable the discharge stroke while the driving gear is disengaged with the piston. Once the engagement section is facing to the piston, the engagement section and the piston are engaged and move the piston in a direction opposite to the direction of the discharge force when the driving gear is rotating. The fact that the engagement section and the disengagement section alternately face the piston while the driving gear keeps rotating enables the water discharge mechanism to continuously perform a cylinder cycle with filling strokes and discharging strokes, thereby discharging water in the form of bullet-like bursts. An idle state of the water discharge mechanism, i.e. a state in which the driving gear is not rotating due to an initiation of a user and the piston is not moving, may be reached when the cylinder is in the filled position in order to provide a mechanism which is ready to discharge water immediately after a rotation of the driving gear is initiated, particularly by activating the trigger, which rotation causes the piston to immediately perform the discharging stroke.

[0012] The water discharge mechanism further comprises a control unit for controlling a movement of an electric motor driving the driving gear. The control unit may control the driving gear's rotation in a reliable and customized manner. The control unit may form part of an electronic system comprising a battery, a display, and a Printed Circuit Board Assembly (PCBA). The control unit may be operatively coupled to the trigger for conveying the user's commands sent from the trigger to the water discharge mechanism. The trigger and the water discharge mechanism may communicate exclusively through the control unit so that no mechanical power transmission between the trigger and the water discharge mechanism, particularly the driving gear, is provided. The control unit may control the water discharge mechanism to realize different operating stages and/or to adapt the rotation of the driving gear to different operating stages. For example, the control unit may stop the rotation of the driving gear when the piston moves from the filled position to the discharged position so that the circumferential length of the disengagement section may be small compared to the circumferential length of the engagement section.

[0013] The above combination of features enables a discharge to be controlled and/or a volume of water to be discharged from the cylinder with a constant pressure regardless of a pressure within a storing system over the filling level from a filled state to an empty state. It further provides a space and weight saving water discharge mechanism. With a reciprocating movement of the piston between the discharged position and the filled position, bursts of water are discharged. This provides a reliable, robust, and user-friendly water discharge mechanism discharging reproducible bursts of water, i.e. bursts which have the same shape for every discharging stroke performed.

[0014] In an embodiment, the water discharge mechanism further comprises a lock-and-release unit functionally arranged between the driving gear and the piston, wherein the lock-and-release unit is configured to lock and release the piston. Lock the piston means that the position of the piston in the filled position is secured, e.g. by a form fit. Release the piston means that the piston may move freely from the lock-and-release unit enabling a relative movement between the piston and the driving gear. The lock-and-release unit, the driving gear, and the piston are arranged in such positions relative to each other that the lock-and-release unit releases the piston when the disengagement section of the driving gear is facing the piston such that the driving gear and the piston are disengaged. The piston may thus be disengaged by the lock-and-release unit when the disengagement section faces the piston thereby disengaging the driving gear and the piston. Due to the lock-and-release unit, a disengagement of the driving gear and the piston does not result in a discharging stroke. Instead, the discharging stroke is only performed once the lock-and-release unit releases the piston. The lock-and-release unit is responsible for locking the piston in the filled position and for releasing the piston for performing the discharging stroke. The lock-and-release unit decreases the forces acting on the engagement section of the driving gear when the piston is in the filled position. Further, it provides a defined position for each stroke enabling the water discharge mechanism to shoot sharp and reproducible bursts of water. It is also possible to shoot exactly one single shot of water. The lock and release unit enables the water discharge mechanism to require a very low starting torque to release the piston from the filled position. When the piston is in the filled position, the discharge force applied by the energy storing element may be maximal because the energy storing element may be in the most compressed condition. Without the lock-and-release mechanism, the discharge force would act on the engagement between the engagement section of the driving gear and the piston during the whole cycle and even in the idle state. For rotating the driving gear such that the disengagement section faces the piston thereby disengaging the driving gear and the piston, a large torque would be required, if it was not for the lock-and-release unit. The lock-and-release unit may provide a form fit with the piston. Such a form fit may be released without requiring large torques. Also, the lock-and-release unit provides a designated and predetermined relative position between the piston and the driving gear which ensures a reliable discharging mechanism.

[0015] In an embodiment, the lock-and-release unit comprises a locking element, particularly a rotatable hook element, configured to lock the piston when it arrives in the filled position. When the piston arrives in the filled position, the disengagement section may be disengaged from the driving gear. The locking element may provide for example a form fit as previously described. The locking element may be pre-tensioned such that it remains in the locking position when no force is applied, e.g. by the piston. The pre-tension may be provided by a spring element, such as a torsion spring. The hook element may be formed of rigid plastic. It may form a first abutment portion, in which the form fit with the piston may be realized. The hook element may further comprise a second abutment portion for receiving another part of the lock-and-release unit for releasing the connection, particularly the form fit or a frictional locking, with the piston. In an embodiment, the locking element is rotatably connected to a housing of the water discharge mechanism, which housing of the water discharge mechanism may be connected to a housing of the toy water gun. Such a rotation connection enables a smooth release of the lock between the lock-and-release unit and the piston as it does not act in the direction against the discharge force. Rotating the locking element against a fixed connection within the housing further provides reliable actuation of the lock-and-release unit because it remains in the same position regardless of the toy water gun's operational state.

[0016] In an embodiment, the lock-and-release unit comprises a releasing element, particularly a pin element, configured to release a lock between the locking element and the piston thereby releasing the piston to move into the discharged position. The locking element of the lock-and-release unit may provide a form fit with the piston for providing a reliable connection. Alternatively, the locking element of the lock and release unit may provide a frictional locking for providing a space saving connection. The releasing element of the lock-and-release unit may engage with the locking element with another form fit thereby releasing, particularly rotating the locking element from the position in which it locks the piston in the filled position. The releasing element may be a part formed of rigid plastic which is adapted to match with the second abutment portion of the locking element for releasing the form fit of the lock-and-release unit and the piston.

[0017] In an embodiment, the release of the lock is initiated by a rotation of the driving gear, wherein the releasing element is particularly fixedly connected to the driving gear so that a rotation of the driving gear is configured to release the lock between the locking element and the piston. This enables an efficient releasing of the locking. Once a user activates a trigger (as described throughout this description), the control unit initiates a rotations of the driving gear. By fixing the releasing element to the driving gear, the rotation of the driving gear ensures a defined positioning and timing of the releasing of the lock-and-release unit and the piston.

[0018] In an embodiment, the piston has a water working surface facing the nozzle outlet and a slider surface facing away from the nozzle outlet, wherein the slider is configured to act on the locking element, particularly rotate the locking element against a pre-tension, when the piston moves from the discharged position to the filled position. Therefore, the movement of the piston may be used for enabling a locking of the piston. The locking element of the lock-and-release unit may be pre-tensioned to be in a position where the piston is locked. When the piston moves from the discharged position to the filled position, the locking element may thus extend into the trajectory of the filling stroke. In order for the locking element to not block the filling stroke, the piston thus has the slider which is adjusted to convert the linear movement of the piston during the filling stroke into a movement, e.g. a rotational movement, of the locking element. Once the piston arrives in the filled position, the lock-and-release surface is not in contact with the locking element any more for ensuring that the piston is properly locked when it is in the filled position.

[0019] In an embodiment, the water discharge mechanism comprises a detector for detecting a filled state when the piston is in the filled position, wherein the detector is operatively coupled to the control unit, wherein the driving gear is configured to rotate until the detector detects the filled state. The detector communicates that the piston is in the filled position to the control unit. The control unit may thus deactivate the electric motor for stopping a rotation of the driving gear. Thus, it is ensured that the driving gear stops rotating at a predetermined position which further contributes to the aim of reproducible water discharges and providing a discharge mechanism which is immediately ready to discharge when the trigger is activated. Also, the detector causes the driving gear, the piston and the lock-and-release unit to remain in their predetermined positions relative to one another. Next to the signal of the detector, the control unit may receive input signals from at least one, preferably two switches arranged at the trigger. The detector may detect a movement of the piston or of an element connected to the piston. The detector may further comprise a buffer unit, e.g. made from a rubber material, which is facing the piston. The buffer unit extends the way to be performed by the piston for being sensed by the detector. This may improve the reliability of the sensing mechanism. Further, the buffer unit protects the detector from moving parts. The buffer unit may further be used as a sealing and may thus combine two functions in one component.

[0020] In an embodiment, the control unit is configured to interrupt a rotation of the driving gear when the piston moves from the filled position to the discharged position. Thus, the length of the disengagement section and accordingly the diameter of the drive gear are reduced, especially if a safety factor is included. Further, the design of the transmission ratio is more flexible due to the omission of a factor. The interruption may be achieved by stopping an electric motor driving the driving gear in a regular manner. The driving gear may be configured to rotate with a constant speed or with a variable speed.

[0021] In an embodiment, a length of the energy storing element exceeds a length of the cylinder unit, wherein the energy storing element is particularly a pre-tensioned spring element with a linear characteristic. Such a characteristic has the effect that the spring element acts on the piston in such a way that the piston is moving with essentially constant speed during the discharging stroke as there is less force required when there is less water to be discharged. The spring rate of the spring element a small is an advantageous variable for controlling that the difference between initial and final force is relatively small by setting the force acting on the piston in the discharged position relatively high. The pre-tension may be of such kind that it acts on the piston also when the piston is in the discharged position for further enhancing the characteristic.

[0022] In an embodiment, a distance between the filled position of the piston and the discharged position of the piston is constant for every stroke of every cycle. This results in a constant amount of water being discharged with every discharging stroke over the entire service life of the toy water gun. One cycle of the piston, i.e. the movement of the piston from the filled position to the discharged position and back to the filled position, may take between 250 ms and 1,000 ms, particularly 500 ms. The constant distance may be achieved by coordinating the position of the driving gear, the lock-and-release unit and the piston. The detector may further contribute to a constant amount of water being discharged.

[0023] In an embodiment, the cylinder unit comprises a cylinder portion, in which the stroke is performed, and a distinct discharge portion comprising the filling inlet and the nozzle outlet. The cylinder portion may be separate from the discharge portion. The portions may have a different shape. The cylinder portion may define a larger volume than the discharge portion. The discharge portion may comprise the volume of one burst of water to be discharged. When the piston performs the discharge stroke, water may thus be pushed from the cylinder portion to the discharge portion pushing the water which has been in the discharge portion out of the nozzle outlet. The cylinder unit may thus not be entirely emptied when the discharge stroke is performed. This allows an efficient discharging of water.

[0024] In an embodiment, a ratio between a length of the disengagement section and a length of the engagement section is large enough for the piston to perform the piston stroke when the driving gear and the piston are disengaged. This ensures that each discharging stroke discharges the same amount of water and that the piston reaches its end position when it is done performing the discharge stroke. A sufficient length of the disengagement section may be reached when the engagement section extends along one fourth or one third of the driving gear's perimeter such that the ratio between the length of the disengagement section and the length of the engagement section is 4 or 3, respectively. Alternatively, a length of the disengagement section is small compared to a length of the engagement section. A rotation of the driving gear may be paused when the piston and the driving gear are disengaged, such that the piston may perform one stroke when the piston and the driving gear are disengaged. Pausing the rotation of the driving gear ensures that each discharging stroke discharges the same amount of water and that the piston reaches its end position when it is in the discharge position.

[0025] The disclosure further relates to a toy water gun for discharging water. The toy water gun comprises a housing, which may have a rear part. The rear part may be shaped to provide an ergonomic toy water gun. The housing may be an injection-molded plastic part. The toy water gun comprises a water discharge mechanism according to the present disclosure. The toy water gun comprises a water tank for storing water. The water tank may be arranged at a rear part of the toy water gun. The water tank and the filling inlet may communicate via a filling fluid line. Such a toy water gun enables a volume of water to be discharged from the cylinder as a single shot of water, especially not a pulsating stream. Due to the dimensions of the water tank and due to the position of the discharging line interface at a front facing portion, a reliable, robust, and user-friendly toy water gun with ergonomic properties is provided.

[0026] In an embodiment, the water tank has an opening and the housing has a closable water supply inlet, wherein the opening is aligned with the water supply inlet such that the water tank is configured to be supplied with water from an external source through the closable water supply inlet. The water supply inlet in that may be arranged at a top part of the toy water gun. Thus, the water tank may be fillable through the external source without the need of an additional pump. The water supply inlet is closable, e.g. through a sliding cap or a screw cap.

[0027] In an alternative embodiment, the toy water gun may comprise a pump, such as a centrifugal pump, which may further be arranged within the filling fluid line. The pump may pump water into the water tank via a supply line, in which a mechanical valve may be arranged. The water tank may have an essentially constant volume. The pump may include a mechanical clamping valve to prevent water from flowing through the pump when not activated. The mechanical clamping valve may be located in the filling line to shut it off. When the trigger is activated to activate a pump switch, the mechanical clamping valve opens by pushing a clamping element aside. The water tank may be equipped with a water sensing unit. The water sensing unit may comprise one to three pairs of sensors for sensing the filling of the tank in a capacitive manner. In an embodiment, the toy water gun may comprise a charging inlet adapted for receiving water from an external source. The charging inlet may be arranged at a front portion of the toy water gun such that a user may hold the front portion into a water reservoir as external source in order to suck water through the charging inlet. In this embodiment, the toy water gun may comprise a pump, such as a centrifugal pump, for pumping water from the external source into the water tank. The charging inlet may be arranged in the vicinity of the nozzle outlet. For example, the nozzle outlet is an upper opening of a front facing surface of the toy water gun while the charging inlet is a lower opening of the front facing surface. The front facing surface is the surface facing the front of the toy gun, i.e. the nozzle. Additionally or alternatively, water may be provided by a pressurized external source. The toy water gun may thus be connected to a charging station providing pressurized water. The charging inlet may comprise a pressure reducer or a pressure relief valve so that the pressurized water from the external source may be supplied to the toy water gun through the charging inlet in a reliable and safe manner. Once the water is supplied by the pressurized external source, the centrifugal pump may not be in use and/or may be bypassed when water is supplied to the toy water gun. A filling line interface and a supply line interface may be arranged at a front facing portion of the water tank. Arranging the discharging interface according to the disclosure at the front facing portion enables the water tank to extend along the entire height of the toy water gun because no space is required in the height direction for the supply interface or the filling interface. A lower center of gravity serves as an optimized counter balance once water is discharged. Geometric definitions such as rear, front, height and length refer to the condition in which the toy gun is regularly used, where rear is the part facing the user, front is the part facing away from the user, height is the dimension perpendicular to the ground with low being closer to the ground than up and length is the dimension along the ground, as will be known to the skilled reader.

[0028] In an embodiment, the water tank extends in a length direction of the toy water gun and a height direction of the toy water gun, wherein the lowest point of the water tank in the height direction is below the lowest point of the water discharge mechanism in a regular condition of the toy water gun. This further enhances the center of gravity of the toy water gun leading to further enhanced ergonomic properties. A regular condition is the condition in which the length direction extends along a ground and a height direction extends perpendicularly to the ground. In an embodiment, a height of the water tank varies along a length direction of the toy water gun so that the rear part height is higher than a front part height and that the shape of the water tank deviates from a rotationally symmetric shape. The tank may have a shape adapted to the shape of the toy water gun. With regard to the conventionally rotational symmetrically water tanks, such a varying shape in the length direction further enhances the ergonomic properties. In an embodiment, the at least one, particularly both, of the filling fluid line and the supply line is or are, respectively, variable in shape, particularly elastically deformable for flexibly disposing the lines within a housing of the toy water gun so that the lines may be arranged flexibly around other components within the housing, such as a pump. This further contributes to the effect that the water tank with the discharging line interface at the front portion may be versatile applicable. Alternatively, the charging fluid line and/or the discharging fluid line may have a fixed shape. In an embodiment, the filling fluid line interface and the supply line interface each comprise a connection socket formed by the water tank in a protruding manner, wherein the filling fluid line is attached onto the connection socket of the filling line interface in a hose-like manner, and wherein the supply line is attached onto the connection socket of the supply line interface in a hose-like manner. Such a connection between the water tank and the charging fluid line at the charging line interface, and the water tank and the discharging fluid line at the discharging line interface provides a reliable supply in a sealed manner of water from the water tank to the water discharge mechanism, respectively from the water tank to the charging inlet.

[0029] The disclosure further relates to a method for discharging water from a toy water gun with a water discharge mechanism according to the present disclosure. The toy water gun performing this method may be a toy water gun according to the present disclosure. The method comprises the step of (a.) providing the water discharge mechanism in an idle state, in which the piston is in the filled position. In the idle state, the piston is in the filled position and the cylinder may be filled with water, as previously described.

[0030] The method comprises the step of (b.) activating, particularly pulling, a trigger, which is operatively coupled to the driving gear via the control unit of the water discharge mechanism as previously described. The trigger may be pulled by a user who wishes to discharge water, e.g. during leisure time activity. The trigger may be electrically connected to a control unit. The signal of a pulled trigger may thus be electrically provided to the control unit which, in turn, starts an electric motor driving an output shaft which is connected to the driving gear via gears as previously described.

[0031] The method comprises the step of (c.) initiating a rotation of the driving gear due to step (b.) for releasing the piston to move freely from the lock and release unit. The rotation of the driving gear may be initiated by the electric motor as previously described. The driving gear has an engagement section and a disengagement section. The position of the driving gear relative to the piston is adjusted such that the piston may move freely from the driving gear immediately after the initiation of the rotation according to this step (c.). Therefore, once the driving gear is rotated starting from the idle state, the piston is free to move.

[0032] The method comprises the step of (d.) performing a discharging stroke driven by the energy storing element for moving the piston from the filled position to the discharged position. During the discharging stroke the piston is disengaged from the driving gear. Therefore, the energy storing element may act on the piston as previously described. The discharging stroke may be performed while the driving gear intermits its rotation. Such an intermission may decrease the energy consumption and the required length of the disengagement section, thus the size of the driving gear. Alternatively, the driving gear may continue its rotation during the discharging stroke.

[0033] The method comprises the step of (e.) providing the piston in the discharged position. The discharged position is reached at the end of the discharging stroke, as previously described.

[0034] The method comprises the step of (f.) rotating the driving gear for engaging the driving gear and the piston. During the discharging stroke, the piston is disengaged from the driving gear. In order to move the piston into the filled positon, an engagement between the driving gear and the piston is required. The rotation of step (f.) may be a continuous rotation since step (c.) or may be a resumed rotation in case the rotation was intermitted, as previously described.

[0035] The method comprises the step of (g.) performing a filling stroke driven by the driving gear for moving the piston from the discharged position to the filled position. During the filling stroke, the cylinder is filled with water which is sucked in from the water tank, as previously described.

[0036] The method comprises the step of (h.) terminating the rotation of step f. when the piston arrives in the filled position. The arriving in the filled position may be detected by a detector which is connected to the control unit which, in turn, stops the driving of the electric motor. Once step (h.) is performed, the water discharge mechanism is again in the idle state, from which step (a.) may be resumed.

[0037] The above combination of features enables a fast, efficient, and reproducible discharging of water. As the termination of one cycle comprising a discharging stroke and a filling stroke is predetermined, the relative position of the driving gear and the piston are the same each time a trigger is activated. This ensures a constant, reproducible discharging of water.

[0038] In an embodiment, the termination of the step of (h.) is caused by a short circuit within an electric motor driving an output shaft which is connected to the driving gear. The termination may thus be achieved by first disconnecting the power supply of the motor and subsequently short-circuiting its connection terminals, essentially resulting in an instant stop of the motor's rotation. Unlike a termination caused by deactivating an electric motor (such as an optional termination during the discharging stroke), the termination caused by the short circuit provides an immediate termination. Therefore, the water discharge mechanism operates with high accuracy. Also, the termination caused by the short circuit may cause the pin of the lock-and-release unit to stop at exactly the same position relative to the hook in each charging-discharging cycle. Said stop is reached within a minimum time duration compared to a stop caused by deactivating an electric motor. Accordingly, the time duration of one charging-discharging cycle may be reduced.

[0039] In an embodiment, steps (a.) to (h.) form one charging-discharging cycle, particularly of a duration of 1 second or less, e.g. 0.5 seconds, which cycle is initiated by a singular actuation of the trigger communicating with the control unit. The user therefore does not have to maintain trigger for driving the driving gear and actuating the water discharge mechanism. Instead, a singular triggering is sufficient. The singular triggering may evoke the electric motor to continuously drive the driving gear until the piston is back in the filled position. Alternatively, the driving gear may be intermitted when the disengagement section is facing the piston, whereas said intermission is performed independently of the user's triggering.

[0040] In an embodiment, the initiation of step (c.) releases the lock between the locking element of the lock-and release unit and the piston. The additional lock-and-release unit decreases the load on the driving gear and the required starting torque as previously described.

[0041] In an embodiment, the termination of step (h.) locks the piston through the locking element, thereby establishing the idle state as previously described.

[0042] In an embodiment, the lock between the locking element and the piston is released by a form fit initiated by a releasing element, particularly a pin element, which is fixedly connected to the driving gear. The lock may be provided by the lock-and-release unit. By rotating the driving gear, a releasing element may act on a locking element, such as the rotatable hook element, thereby releasing the piston. The form fit further contributes to the defined releasing of the lock-and-release unit and the piston.

[0043] In an embodiment, the method comprises the step of detecting a position of the piston when the piston arrives in the filled position. The step of detecting may be performed by a detector as previously described. The detector may detect a filled state when the piston is in the filled position. The detector may be operatively coupled to a control unit, wherein the driving gear is configured to rotate until the detector detects the filled state.

[0044] In an embodiment, the rotation of the driving gear is stopped for a predetermined duration during the discharge stroke. The driving gear may be stopped by deactivating the electric motor driving the driving gear. The deactivation may differ from the termination caused by a short-circuit. The stop of the driving gear during the discharge stroke renders it possible to reduce a length of the disengagement section along the perimeter of the driving gear.

[0045] A toy water gun according to the present disclosure may have several operating modes. For example, a single activation of the trigger may result in a single discharge of water, i.e. a single shot. The disclosed mechanism provides for an immediate discharge of water once the trigger is activated such that there is no delay. In another mode, the user may hold the trigger to discharge shots at the cycle frequency until the trigger is deactivated. Further, the toy water gun may omit an on/off button such that the toy water gun is in an active state once the trigger is activated.

Brief Description of the Drawings

[0046] The present disclosure will be more readily appreciated by reference to the following detailed description when being considered in connection with the accompanying drawings in which:

Figure 1

shows a front portion of a toy water gun with a water discharge mechanism;

Figure 2

shows an enlarged view of a driving gear 7;

Figure 3

shows the water discharge mechanism in a first operational stage;

Figure 4

shows the water discharge mechanism in a second operational stage;

Figure 5

shows the water discharge mechanism in the first operational stage from a different viewing angle;

Figure 6

shows an enlarged view of the lock and release unit; and

Figure 7

shows the toy water gun.

Detailed Description of Embodiments

[0047] In the following, the invention will be explained in more detail with reference to the accompanying figures. In the figures, like elements are denoted by identical reference numerals and repeated description thereof may be omitted in order to avoid redundancies.

[0048] Figure 1 shows a water discharge mechanism 1 arranged in a toy water gun 100. The water discharge mechanism 1 comprises a cylinder unit 2 with a filling inlet 3 for receiving water and a nozzle outlet 4 for discharging water. A piston 5 is configured to perform a piston stroke in the cylinder unit 2 wherein the piston stroke extends between a filled position P1 and a discharged position P2. The piston 5 is configured to push water out of the nozzle outlet 4. In figure 1, the piston 5 is in the discharged position P2. Accordingly, a single burst of water has just been discharged by the water discharge mechanism 1. On the side of the piston 5 facing away from the nozzle outlet 4, an energy storing element 6 is arranged. The energy storing element 6 is configured to apply a discharge force on the piston 5. The water discharge mechanism 1 further comprises a driving gear 7 which has an engagement section 8 and a disengagement section 9. The engagement section 8 may engage with the piston 5 for moving the piston 5 against the discharge force of the energy storing element 6 into the filled position P1. The disengagement section 9, in turn, is configured to disengage the driving gear 7 and the piston 5, thereby fulfilling a criterion for moving the piston 5 into the discharged position P2. The water discharge mechanism 1 has a control unit 10, which controls a movement of an electric motor 11 driving the driving gear 7.

[0049] The cylinder unit 2 comprises a cylinder portion 12, in which the piston 5 performs its piston stroke from the filled position P1 to the discharged position P2. The cylinder portion 12 is cylindrical. The cylinder unit 2 further comprises a discharge portion 13 which adjoins the cylinder portion 12. The discharge portion 13 has an elongated shape. The discharge portion 13 provides the filling inlet 3 as well as the nozzle outlet 4. When the piston 5 reciprocates in the cylinder portion 12, water is sucked into the cylinder unit 2 and pushed out of the cylinder unit 2. The discharge portion 13 may be filled with water regardless of the operating state of the piston 5. In the filled position P1, the entire cylinder unit 2 is filled with water. In the discharged position P2, only the discharge portion 13 is filled with water. The energy storing element 6 may be a spring element. It may be designed such that the force acting on the piston 5 is in the filled position P1 twice as high as the force acting on the piston 5 in the discharged position P2. In the operating state shown in figure 1, the forces acting on the piston 5 may be 20 N.

[0050] The driving gear 7 has the engagement section 8 and the disengagement section 9. The engagement section 8 may be a toothed section extending along a circumferential length of the driving gear 7. Accordingly, the disengagement section 9 may be a toothless section extending along a circumferential length of the driving gear 7 (see figure 2 for further details). The piston 5 comprises a gear section 14. The gear section 14 is a portion of the piston 5 facing towards the driving gear 7. The length of the gear section 14 may essentially correspond to the circumferential length of the engagement section 8 or may be slightly higher. The gear section 14 and the engagement section 8 mesh with each other when the piston 5 is moved from the discharged position P2 to the filled position P1. When the driving gear 7 is driven by the electric motor 11, and when the engagement section 8 meshes with the gear section 14, the piston 5 is moving against the force of the energy storing element 6 in the direction facing away from the nozzle outlet 4.

[0051] Figure 2 is an enlarged view of the driving gear 7. Presently, the engagement section 8 is a toothed section. The disengagement section 9 is a toothless section. Approximately one third of the driving gear's perimeter is equipped with the engagement section 8, two thirds of the driving gear's perimeter are equipped with the disengagement section 9. Independent of the engagement section 8 and the disengagement section 9, the driving gear 7 has an outer gear shape 18, which is configured to mesh with a second wheel 19 of a transmission. The outer gear shape 18 has thus no piston engaging function. Instead, it only receives the rotation from the second wheel, which is one wheel of the transmission between the electric motor 11 and the driving gear 7. The transmission is designed to convert high rotational speeds from the electric motor 11 into low rotational speeds at the driving gear 7 resulting in the desired movement of the piston 5.

[0052] Figure 3 shows the water discharge mechanism 1 in an operational state, in which the piston 5 is in the filled position P1. A lock-and-release unit 15 is functionally arranged between the driving gear 7 and the piston 5. The lock-and-release unit 15 comprises a locking element 16 in the form of a rotatable hook element which locks the piston 5 when it arrives in the filled position P1 (see figure 6 for further details). In figure 3, the locking element 16 locks a slider 20 of the piston 5. The locking element 16 has a first abutment portion 21 formfitting the slider 20. Accordingly, the piston 5 is locked. The releasing element 17 is attached to the driving gear 7. A rotation of the driving gear 7 therefore moves the releasing element 17. The locking element 16 has a second abutment portion 22, which is configured to be contacted by the releasing element 17. Once the driving gear 7 has a respective rotational position, the releasing element 17 contacts the second abutment portion 22 of the locking element 16. A further rotation of the driving gear 7 rotates the locking element 16 due to the contact between the releasing element 17 and the second abutment portion 22. Once the rotation of the locking element 16 reaches a threshold position, the form fit between the slider 20 and the locking element 16 is released. Accordingly, the piston 5 is not locked anymore and the energy storing element 6 pushes the piston 5 from the filled position P1 to the discharged position P2. In the operating state shown in figure 3, the forces acting on the piston 5 may be 40 N.

[0053] Figure 4 shows the water discharge mechanism 1 in an operational state, in which the piston 5 is in the discharged position P2. Accordingly, the lock-and-release unit 15 does not lock the movement of the piston 5. The engagement section 8 of driving gear 7 meshes with the gear section 14 of the piston 5. When the driving gear 7 is rotated, the rotational movement is transmitted to the piston 5 via the gear section 14. The rotational force supplied by the electric motor 11 and provided to the piston 5 by the driving gear 7 is higher than the axial force provided by the energy storing element 6 acting towards the piston 5. Thus, the rotation of the driving gear 7 moves the piston 5 from the discharged position P2 to the filled position P1. When the piston 5 moves from the discharged position P2 to the filled position P1, an inclined sliding surface 23 of the slider 20 acts on the locking element 16 and pushes it down. Once the inclined sliding surface 23 has passed the locking element in the piston's movement from the discharged position P2 to the filled position P1, a pretension of the locking element 16 pushes the locking element 16 back into its regular position. In the regular position of the locking element 16, when the piston 5 is in the filled position P1, the first abutment portion 21 form fits the slider 20 of the piston 5 as previously described. When comparing the position of the releasing element 17 in figures 3 and 4, it becomes apparent that the driving gear 7 has rotated approximately 170° to 190° between the operational states shown in figures 3 and 4.

[0054] A charging/discharging cycle is initiated by a trigger 24 (see figures 1, 4). When a user activates the trigger 24, a signal is sent to the control unit 10. In this state, the piston 5 is in the filled position P1. The control unit 10 receives the signal from the trigger 24 and, as a response, causes the electric motor 11 to rotate. The rotation of the electric motor 11 is transmitted to the driving gear 7 via a transmission. A releasing element 17 is fixedly connected to the driving gear 7. The rotation of the driving gear 7 thus moves the releasing element 17. The movement of the releasing element 17 causes a contact between the releasing element 17 and the second abutment portion 22 of the locking element 16. Said contact moves the locking element 16 thereby releasing the lock between the lock-and-release unit 15 and the piston 5. The releasing element 17 is arranged such that the contact between the releasing element 17 and the locking element 16 takes place immediately after the rotation of the driving gear 7 is initiated. When the lock is released, the disengagement section 9 of the driving gear 7 faces the piston 5. Accordingly, the piston 5 and its gear section 14 may move independently of the rotation of the driving gear 7. As the piston 5 is pretensioned by the energy storing element 6 and there is no lock between the piston 5 and the lock-and-release unit 15, the piston 5 moves from the filled position P1 to the discharged position P2. This piston stroke causes the water in the cylinder unit 2 to be discharged from the nozzle outlet 4. During the piston stroke, the control unit 10 may cause the electric motor 11 to intermit the rotation of the driving gear 7. This enables a slim and efficient design of the water discharge mechanism 1. When the piston 5 arrives in the discharged position P2, the engagement section 8 of the driving gear 7 starts to mesh with the gear section 14 of the piston 5. Accordingly, the piston 5 is moved against the force applied by the energy storing element 6. The movement of the piston 5 causes the sliding surface 23 to rotate the locking element 16 such that the piston 5 may form the form fit with the locking element 16 when the lock-and-release unit 15 locks the piston 5. When the piston 5 arrives in the filled position P1, a detector 25 detects the piston's position and conveys a respective signal to the control unit 10 which causes the electric motor 11 to stop, thereby stopping the rotation of the driving gear 7. In this state, the engagement between the engagement section 8 and the gear section 14 is released. This, however, does not cause the piston 5 to move into the discharged position P2, because the lock-and-release unit 15 locks the piston's movement. Thus, when the piston 5 arrives in the filled position P1, the charging/discharging cycle initiated by the trigger 24 is completed. The trigger 24 is only activated once for one charging/discharging cycle. The signal sent from the trigger 24 to the control unit 10 therefore causes the entire charging/discharging activated by the trigger and deactivated by the piston's position.

[0055] Figure 5 shows the water discharge mechanism 1 where the piston 5 is in the filled position P1 from the opposing side compared to figure 3. The detector 25 is arranged at a position close to the rear end of the piston 5 when it is in the filled position P1. The detector 25 detects when the piston 5 is in the filled position P1. The detector 25 communicates to the control unit 10 when the piston 5 arrives in the filled position P1 which causes the control unit 10 to stop the rotation of the driving gear 7. Also, the detector 25 causes the driving gear 7, the piston 5 and the lock-and-release unit 15 to remain in their predetermined positions relative to one another. The detector 25 may comprise a buffer unit 27 which is arranged to face the gear section 14 of the piston 5. The buffer unit 27 may be made from a gum material. It extends the way to be performed by the piston 5 for being sensed by the detector 25. An output shaft of the electric motor 11 forms a bevel gear with the transmission.

[0056] Figure 6 shows an enlarged view of the lock-and-release unit 15 in a locked state, where the piston 5 is in the filled position P1. The releasing element 17 is fixedly connected to the driving gear 7 and has an almond shape. The almond shape is designed to match with the second abutment portion 22 of the locking element 16. Once the rotation of the driving gear 7 causes the releasing element 17 to contact the second abutment portion 22, the locking element 16 rotates around its anchor point. Accordingly, the lock between the lock-and-release unit 15 and the slider 20 of the piston 5 is released.

[0057] Figure 7 shows the toy water gun 100. The water discharge mechanism 1 is arranged in a front portion of the toy water gun 100. The trigger 24 is arranged at a middle portion of the toy water gun 100. A rear portion of the toy water gun 100 includes a water tank 28. The water tank 28 is arranged within a housing 29 of the toy water gun 100. The water tank 28 has an opening 30 through which water may be supplied to the water tank 28. The housing 29 has a closable water supply inlet 31, which is aligned with the opening 30. When water from an external source is provided to the water tank 28, the water supply inlet 31 is opened, e.g. through a slidable cap or a screw cap. As the water supply inlet 31 is aligned to the opening 30, water supplied to the water supply inlet 31 is filled into the water tank 28. In a height direction of the toy water gun 100, the water tank 28 extends along the entire height of the rear portion of the toy water gun 100. This results in the space saving water storing mechanism with enhanced ergonomic properties. At a front facing portion of the water tank 28, a filling line interface 32 is provided. The filling line interface 32 may be provided at a lower portion of the water tank 28 facing at least partially downwards to increase the emptying properties of the tank. A filling line may be coupled onto the filling line interface 32 and to the filling inlet 3 for providing water from the water tank 28 to the cylinder unit 2. A piston stroke from the discharged position P2 to the filled position P1 may suck in the water from the water tank 28 via the filling line. Accordingly, the toy water gun 100 of the embodiment in figure 7 is capable of providing sharp bursts of water without requiring a pump.

[0058] It will be obvious for a person skilled in the art that these embodiments and items only depict examples of a plurality of possibilities. Hence, the embodiments shown here should not be understood to form a limitation of these features and configurations. Any possible combination and configuration of the described features can be chosen according to the scope of the invention.

Reference signs

[0059] 

1

water discharge mechanism

2

cylinder unit

3

filling inlet

4

nozzle outlet

5

piston

6

energy storing element

7

driving gear

8

engagement section

9

disengagement section

10

control unit

11

electric motor

12

cylinder portion

13

discharge portion

14

gear section

15

lock-and-release unit

16

locking element

17

releasing element

18

outer gear shape

19

second wheel

20

slider

21

first abutment portion

22

second abutment portion

23

sliding surface

24

trigger

25

detector

26

water working surface

27

buffer unit

28

water tank

29

housing

30

opening

31

water supply inlet

32

filling line interface

100

toy water gun

Claims

1. A water discharge mechanism (1) of a toy water gun (100), comprising

- a cylinder unit (2) with a filling inlet (3) for receiving water and a nozzle outlet (4) for discharging water;

- a piston (5) configured to perform a piston stroke in the cylinder unit (2), wherein the piston stroke extends between a filled position (P1) and a discharged position (P2);

- an energy storing element (6), particularly a spring element, configured to apply a discharge force on the piston (5);

- a driving gear (7) with an engagement section (8), particularly a toothed section, and a disengagement section (9), particularly a toothless section,

wherein the engagement section (8) is configured to engage with the piston (5) for moving the piston (5) against the discharge force into the filled position (P1), and

wherein the disengagement section (9) is configured to disengage the driving gear (7) and the piston (5); and

- a control unit (10) for controlling a movement of an electric motor (11) driving the driving gear (7).

2. The water discharge mechanism (1) according to claim 1 further comprising a lock-and-release unit (15) functionally arranged between the driving gear (7) and the piston (5), wherein the lock-and-release unit (15) is configured to lock and release the piston (5).

3. The water discharge mechanism (1) according to claim 2, wherein the lock-and-release unit (15) comprises a locking element (16), particularly a rotatable hook element, configured to lock the piston (5) when it arrives in the filled position (P1).

4. The water discharge mechanism (1) according to one of the claims 2-3, wherein the lock-and-release unit (15) comprises a releasing element (17), particularly a pin element, configured to release a lock between the locking element (16) and the piston (5).

5. The water discharge mechanism (1) according to claim 4, wherein the release of the lock is initiated by a rotation of the driving gear (7), wherein the releasing element (17) is particularly fixedly connected to the driving gear (7).

6. The water discharge mechanism (1) according to one of the claims 3-5, wherein the piston (5) has a water working surface (26) facing the nozzle outlet (4) and a slider (20) facing away from the nozzle outlet (4), wherein the slider (20) is configured to act on the locking element (16), particularly rotate the locking element (16) against a pre-tension, when the piston (5) moves from the discharged position (P2) to the filled position (P1).

7. The water discharge mechanism (1) according to one of the preceding claims, further comprising a detector (25) for detecting a filled state when the piston (5) is in the filled position (P1), wherein the detector (25) is operatively coupled to the control unit (10), wherein the driving gear (7) is configured to rotate until the detector (25) detects the filled state.

8. The water discharge mechanism (1) according to one of the preceding claims, wherein the control unit (10) is configured to interrupt a rotation of the driving gear (7) when the piston (5) moves from the filled position (P1) to the discharged position (P2).

9. The water discharge mechanism (1) according to one of the preceding claims, wherein a length of the energy storing element (6) exceeds a length of the cylinder unit (2), wherein the energy storing element (6) is particularly a pre-tensioned spring element with a linear characteristic.

10. The water discharge mechanism (1) according to one of the preceding claims, wherein a distance between the filled position (P1) of the piston (5) and the discharged position (P2) of the piston (5) is constant for every stroke.

11. The water discharge mechanism (1) according to one of the preceding claims, wherein the cylinder unit (2) comprises a cylinder portion (12), in which the stroke is performed, and a distinct discharge portion (13) comprising the filling inlet (3) and the nozzle outlet (4).

12. A toy water gun (100) for discharging water, comprising

- a housing (29) ;

- the water discharge mechanism (1) according to any of the preceding claims; and

- a water tank (28) for storing water.

13. The toy water gun (100) according to claim 12, wherein the water tank (28) has an opening (30) and the housing (29) has a closable water supply inlet (31), wherein the opening (30) is aligned with the water supply inlet (31) such that the water tank (28) is configured to be supplied with water from an external source through the closable water supply inlet (31).

14. A method for discharging water from a toy water gun (100) with a water discharge mechanism (1) according to claims 1-11, comprising the steps of:

a. providing the water discharge mechanism (1) in an idle state, in which the piston (5) is in the filled position (P1);

b. activating a trigger (22), which is operatively coupled to the driving gear (7) via the control unit (10);

c. initiating a rotation of the driving gear (7) due to step b. for releasing the piston (5);

d. performing a discharging stroke driven by the energy storing element (6) for moving the piston (5) from the filled position (P1) to the discharged position (P2) when the driving gear (7) and the piston (5) are disengaged;

e. providing the piston (5) in the discharged position (P2);

f. rotating the driving gear (7) for engaging the driving gear (7) and the piston (5);

g. performing a filling stroke driven by the driving gear (7) for moving the piston (5) from the discharged position (P2) to the filled position (P1); and

h. terminating the rotation of step f. when the piston (5) arrives in the filled position (P1).

15. The method according to claim 14, wherein the termination of step h. is caused by a short circuit within an electric motor (11) driving an output shaft which is connected to the driving gear; and /or

wherein steps a. to h. form one charging-discharging cycle, which cycle is initiated by a singular actuation of the trigger (24) communicating with the control unit (10) and/or;

wherein the termination of step h. locks the piston (5) through the locking element (16).

16. The method according to one of the claims 14-15, wherein the initiation of step c. releases the lock between the locking element (16) and the piston (5), wherein the lock between the locking element (16) and the piston (5) is particularly released by a form fit initiated by a releasing element (17), further particularly a pin element, which is fixedly connected to the driving gear (7).

17. The method according to one of the claims 13-16, comprising the step of detecting a position of the piston (5) when the piston (5) arrives in the filled position; and/or
wherein the rotation of the driving gear (7) is stopped for a predetermined duration during the discharge stroke.

Drawing