BATTERY-POWERED PORTABLE CUTTING TOOLS

Description

[0001] This invention relates to a battery-powered portable cutting tool according to the preamble of claim 1, such as a chainsaw.

[0002] Such an apparatus is known from US 5150523 A1. Chainsaws and other battery-powered portable cutting tools, such as hedge trimmers, generally comprise a housing supporting a battery, a motor and a cutting element. The battery powers the motor, which in turns drives the cutting element to cut. In a chainsaw, the blade is an endless chain loop carrying cutting elements, and the motor drives the chain along its length, such that the cutting elements will be driven through whatever is to be cut.

[0003] It is desirable to attempt to ensure that the tool activates only when desired; otherwise, a user could be surprised by an inadvertent activation of the chainsaw, particularly if that user is inexperienced in the use of such tools. With petrol- or gasoline-powered portable cutting tools, it is obvious when such tools are potentially active, as the engine that powers those tools makes noise when idle. A battery-powered cutting tool, on the other hand, makes no noise when idle.

[0004] According to a first aspect of the invention, there is provided a battery-powered portable cutting tool, comprising: a housing, a cutting element supported by the housing, an electric motor coupled to the cutting element so as to drive the cutting element to cut, a battery electrically coupled to the motor so as to supply electric current to the motor and a control circuit arranged to control the supply of electric current to the motor from the battery,
in which the control circuit comprises a main switch operable by a user and an auxiliary switch also operable by a user;
in which the control circuit has:

an active state in which operation of the main switch by the user allows electric current to flow to the motor so as to cause the cutting element to be driven; and

an inactive state in which operation of the main switch does not allow electric current to flow to the motor and so the motor does not drive the cutting element;

in which operation of the auxiliary switch causes the control circuit to change between the active and inactive states;

and in which the auxiliary switch comprises a hook from which the tool can be suspended, the auxiliary switch being arranged such suspension of the tool from the hook causes the control circuit to change to the inactive state.

[0005] Thus, the act of suspending the tool will cause it to become inactive; a user cannot be surprised by cutting element being driven should the main switch be inadvertently activated.

[0006] The hook may be pivotally mounted on the housing and may have a protruding position, in which the tool can be suspended from the hook, and a folded-in position, where the hook is folded further in towards the housing relative to the protruding position; for example, in the folded-in position, the hook may be flat against the housing. The action of folding the hook into the folded-in position may cause the control circuit to move into the active state.

[0007] Alternatively, the hook may be mounted on the housing by means of a load sensor, the auxiliary switch causing the control circuit to change to the inactive state should the load on the hook through the load sensor exceed a predetermined limit, which may be the weight, or at least 50%, 75% or 90% of the weight, of the tool. As such, this can sense whether the tool is being suspended through the hook, and deactivate the tool if so.

[0008] The tool may be a chainsaw or hedge trimmer.

[0009] Thus, the auxiliary switch can be used to deactivate the tool should it not be in an appropriate position for use. As such, this can prevent inadvertent activation of such a tool. One of various different inappropriate states for a cutting tool is the situation in which this cutting tool is in suspended position.

[0010] In one example, the auxiliary switch may be arranged to determine whether the tool is being suspended; as such, the tool may be one according to the first aspect of the invention. Alternatively, where the tool is a chainsaw having a chain brake operable by a user to brake movement of the chain, the auxiliary switch may be arranged to determine whether the chain brake has been applied and, if so, place the control circuit in the inactive position; as such, the tool may be one according to the second aspect of the invention.

[0011] For the preceding aspect of the invention, the control circuit may be arranged with the main switch and the auxiliary switch in series; thus, in order for current to flow through the control circuit, both switches must be opened.

[0012] The control circuit may be arranged to enter the inactive state if the main switch is not activated for a pre-determined period of time. This means that if the tool is not used for the period, action will need to be taken by the user in order to reactivate it, thus reducing the chance of the user being surprised by an inadvertent operation.

[0013] In such a case, the control circuit may be arranged such that manipulation of the auxiliary switch after the control circuit has deactivated after the passage of the period of time causes the control circuit to enter the active state. This is a convenient way of waking a dormant tool.

[0014] There now follows, by way of example only, embodiments of the invention, described with reference to the accompanying drawings, in which:

Figure 1 shows a side elevation of a chainsaw according to an embodiment of the invention, in the active state;

Figure 2 shows a perspective view of the chainsaw of Figure 1;

Figure 3 shows a side elevation of the chainsaw of Figure 1, in an inactive state;

Figure 4 shows a perspective view of the chainsaw of Figure 1, in the inactive state;

Figure 5 shows a circuit diagram of the electric circuit controlling the chainsaw of Figure 1;

Figure 6 shows an alternative embodiment of the circuit of Figure 5; and

Figure 7 shows a first auxiliary switch according to a further embodiment of the invention.

[0015] A chainsaw according to an embodiment of the invention is shown in the accompanying drawings. It comprises a housing 1 supporting a cutting element 2 (shown only in Figure 1). The cutting element comprises an elongate support 3 over which an endless loop of cutting chain 4 runs. The cutting chain has cutting elements on each link.

[0016] In order to drive the cutting chain 4, a battery 5 and a motor 6 (both shown in Figure 5) are provided in the housing. The motor 6 acts to rotate a drive wheel 7 and so drive the chain 4 around the support 3 when current is supplied to it by the battery 5.

[0017] The main control a user has over the operation of the chainsaw is by the use of the main switch 8. The user must squeeze both parts 8a, 8b of the main switch in order to allow current to flow from the battery 5 to the motor 6 and so drive the cutting chain 3 to cut.

[0018] The chainsaw is also provided with a chain brake, which acts to physically brake the rotation of the drive wheel 7. This is activated by the user pushing forwards (that is, towards the blade, and to the left in the Figures) a chain brake handle 13. This is useful if the user wishes to stop the chainsaw quickly. The chain brake may also active through the action of inertia should a kickback event occur.

[0019] However, in order to prevent inadvertent activation of the chainsaw, the chainsaw is provided with a control circuit 9, which controls the passage of current from the battery 5 to the motor 6. This is shown in more detail in Figure 5 of the accompanying drawings. The control circuit 9 comprises three switches in series; accordingly, in order for current to flow from the battery 5 to the motor 6 all three switches must be closed.

[0020] The first switch in the series is the main switch 8; this functions as discussed above, with the user squeezing the two parts 8a, 8b in order to activate the chainsaw and so cause the chainsaw to cut.

[0021] The remaining two switches 10, 11 are first and second auxiliary switches respectively. If either of these two switches are open, then the control circuit 9 is in an inactive state; activate of the main switch 8 will not cause the chainsaw to cut. However, if both of the auxiliary switches 10, 11 are closed, then the control circuit 9 is in an active state, and the main switch will function to operate the chainsaw.

[0022] The first auxiliary switch 10 comprises a hook 12 pivotally mounted on the rear (that is, the end opposite the cutting element 2) of the housing 1. The hook 12 therefore has two positions: a folded-in position, shown in Figures 1 and 2 of the accompanying drawings, in which the hook 12 lies against the housing, and a protruding position, shown in Figures 3 and 4 of the accompanying drawings, in which the hook 12 protrudes normal to the housing. In the protruding position, the hook 12 can be used to suspend the chainsaw, typically so it can be hoisted up a tree that is being sawn.

[0023] As it is undesirable that the chainsaw operates whilst being suspended from the hook 12, the first auxiliary switch 10 is electrically open when the hook 12 is in the protruding position of Figures 3 and 4 of the accompanying drawings. The first auxiliary switch 10 is electrically closed by moving the hook 12 into the folded-in position of Figures 1 and 2 of the accompanying drawings. Thus, the control circuit 9 will be in the inactive state if the hook 12 is in the protruding position and so could be used to suspend the chainsaw, whereas the control circuit 9 could be in the active state with the hook 12 in the folded-in position. Thus, it is difficult if not impossible for the chainsaw to be activated with the chainsaw suspended from the hook 12.

[0024] In alternative embodiment, the first auxiliary switch 110 is as shown in Figure 7 of the accompanying drawings. In this embodiment, rather than being pivotally mounted on the housing 101, the hook 112 is provided as protruding directly outwards from the housing 101. The hook 112 is mounted on the housing 101 through a load sensor 115, such as a strain gauge. The load sensor determines the force applied by the hook 112 on the housing 100. If the force on the load sensor due to the hook is greater than a predetermined limit - say 50% of the weight of the chainsaw - then the first auxiliary switch will open, and no current can pass between the terminals 116. If the force on the load sensor due to the hook is less than this limit, the first auxiliary switch will close, allowing current to flow between the terminals 116. Thus, suspending the chainsaw from the hook 112 will mean that the weight of the chainsaw will act through the hook, causing the first auxiliary switch 110 to open.

[0025] Returning now to the embodiment of Figures 1 to 6, the second auxiliary switch 11 is coupled to the chain brake handle 13. On activation of the chain brake by the chain brake handle, the second auxiliary switch 11 will open, putting the control circuit 9 into the inactive state. This is useful, as if the chain brake handle 13 has been activated (pushed away from the user, towards the cutting element 2), then it must be desired to stop the cutting element 2. Similarly, the second auxiliary switch 11 will close if the chain brake handle is reset, allowing the control circuit 9 to return to the active state (dependent upon the state of the first auxiliary switch).

[0026] Thus, by providing an auxiliary switch coupled to the chain brake handle, the motor can be stopped at the same time that the chain brake is being used to stop the chain, which may lead to quicker stopping of the chain. Furthermore, if the chain brake is applied a user is unlikely to desire to activate the motor against the brake, and so the inactive state is appropriate, as it will prevent any inadvertent activation of the motor against the brake, which could lead to overheating of the motor.

[0027] Additionally or alternatively, the second auxiliary switch can be coupled to the chain brake handle, but be activatable not only when the chain brake is activated. Thus, the chain brake handle may have three positions: a first position pushed fully away from the user towards the chain, where the chain brake is activated and at the same time the control circuit of the chainsaw is put into the inactive state; a second, neutral and intermediate, position in which the tool can be used, and a third, switching position pulled closest to the user and the housing 1. Movement of the chain brake handle into this third switching position can act to either switch the control circuit of the chainsaw into the active state, or can act to toggle the chainsaw between the inactive and active states. Preferably the chain brake handle will not be stable in this third switching position and will tend to return to the second position.

[0028] Thus this aspect of the invention allows for different alternatives how the chainsaw can be activated or deactivated using the chain brake handle.

[0029] In the preferred embodiment the chainsaw will always put into the inactive state, when the user is pushing the chain brake handle into the first position towards the chain. Pulling the chain brake handle back into the intermediate (working) second position will keep the chainsaw inactive. By further pulling the chain brake handle into the third position closest to the user the chain saw will be put into its active state again. Preferably the chain brake handle will be spring biased in a way that this third position is not a stable position, thus the chain brake handle will automatically move back from the third position into the second position when the user releases it. With this very intuitive configuration a pushing of the chain brake handle will result in putting the chainsaw into an inactive mode whilst a pulling action will place the chainsaw into the active state to an activation of the chainsaw.

[0030] In an alternative embodiment the movement of the chain brake handle between the second and third position could toggle the chainsaw between the active and the inactive state. Thus if the chain brake handle is in the second position and the chainsaw is in the inactive state the pulling of the chain brake handle towards the third position will put the chainsaw into activate state. In case that the chain brake handle is in the second position and the chainsaw is in active state the pulling of the chain brake handle into the third position would put the chainsaw into an inactive state. With this embodiment or in a further alternative embodiment the movement of the chain brake handle from the first position towards the second position could already put the chainsaw into an active state.

[0031] In addition, a power switch 20 can be provided, which can cut all power from the chainsaw; alternatively, this switch 20 can act as a further auxiliary switch, arranged to toggle the chainsaw between the active and inactive states, as described with the third embodiment of the invention. In this case switch 20 incorporates at least 3 different switching positions. Preferably this kind of switch is combined with the activation and deactivation procedure as described above connected to the chain brake handle 13. Specially then it is of advantage if the switch 20 is oriented on the chainsaw as shown with Figures 1 to 4. Thus, preferably the first position to activate the chain saw is located away from the chain towards the user and the third switching position to deactivate the chain is located toward the chain or chain brake handle. With an arrangement like this, the directions of movement to activate or to deactivate the chainsaw are the same for the switch 20 as for the chain brake handle 13 which results in a intuitive handling for the user.

[0032] In a further embodiment extending the present embodiment, the control circuit has been extended as shown in Figure 6 of the accompanying drawings. Equivalent reference numerals to the first embodiment are used, raised by 50.

[0033] In this embodiment, the functioning of the chainsaw is largely as described above. The control circuit 59 comprises a main switch 58 and first and second auxiliary switches 60 and 61. However, a third auxiliary switch 70 is provided, together with a timing circuit 71. The timing circuit is coupled to the main switch 58; if the main switch is not activated within a predetermined period (say anything from 30 seconds to 5 minutes), then the timing circuit will open the third auxiliary switch 70, thus placing the control circuit 59 in the inactive state.

[0034] This is useful in making a chainsaw that has not been used for a period of time dormant. A user is therefore less likely to be surprised should they inadvertently operate the main switch 58.

[0035] In order to provide for reactivating the chainsaw, the timing circuit 71 is also coupled to the first auxiliary switch 60, such that, should the user move the hook, the timing circuit will close the third auxiliary switch 70. Accordingly, in order to put the chainsaw back into the active state, all a user need to do is move the hook from the folded-in position to the protruding position and back again. Alternatively, the third auxiliary switch 70 may be directly engagable by a user; for example, if the device is dormant, then by manipulating the power switch 20 of Figure 1 off and on again, a user can reactivate the device.

Claims

1. A battery-powered portable cutting tool, comprising: a housing (1), a cutting element (2) supported by the housing, an electric motor (6) coupled to the cutting element (2) so as to drive the cutting element (2) to cut, a battery (5) electrically coupled to the motor (6) so as to supply electric current to the motor (6) and a control circuit (9) arranged to control the supply of electric current to the motor (6) from the battery (5),
in which the control circuit (9) comprises a main switch (8) operable by a user and an auxiliary switch (10, 110) also operable by a user;
in which the control circuit (9) has:

an active state in which operation of the main switch (8) by the user allows electric current to flow to the motor (6) so as to cause the cutting element (2) to be driven; and

an inactive state in which operation of the main switch (8) does not allow electric current to flow to the motor (6) and so the motor does not drive the cutting element (2);

in which operation of the auxiliary switch (10, 110) causes the control circuit to change between the active and inactive states;

characterised in that the auxiliary switch comprises a hook (12, 112) from which the tool can be suspended, the auxiliary switch (10, 110) being arranged such that suspension of the tool from the hook (12, 112) causes the control circuit (9) to change to the inactive state.

2. The tool of claim 1, in which the hook (12) is pivotally mounted on the housing and has a protruding position, in which the tool can be suspended from the hook (12), and a folded-in position, where the hook (12) is folded further in towards the housing (1) relative to the protruding position.

3. The tool of claim 2, in which the action of folding the hook (12) into the folded-in position causes the control circuit (9) to move into the active state.

4. The tool of any preceding claim, in which the hook (112) is mounted on the housing (101) by means of a load sensor (115), the auxiliary switch (110) causing the control circuit (9) to change to the inactive state should the load on the hook (112) through the load sensor (115) exceed a predetermined limit.

5. The tool of any preceding claim, being a chainsaw or a hedge trimmer.

6. The tool of any preceding claim, in which the control circuit (9) is arranged with the main switch (8) and the auxiliary switch (10, 11, 110) in series.

7. The tool of any preceding claim, in which the control circuit (9) is arranged to enter the inactive state if the main switch (8) is not activated for a pre-determined period of time.

8. The tool of claim 7, in which the control circuit (9) is arranged such that manipulation of the auxiliary switch (10, 11, 110) after the control circuit (9) has deactivated after the passage of the period of time causes the control circuit (9) to enter the active state.

Ansprüche

1. Batteriebetriebenes tragbares Schneidwerkzeug, umfassend: ein Gehäuse (1), ein von dem Gehäuse getragenes Schneidelement (2), einen Elektromotor (6), der mit dem Schneidelement (25) gekoppelt ist, um das Schneidelement (2) zum Schneiden anzutreiben, eine Batterie (5), die elektrisch mit dem Motor (6) gekoppelt ist, um elektrischen Strom an den Motor (6) zuzuführen, sowie eine Steuerschaltung (9), die angeordnet ist, um die Zufuhr von elektrischem Strom von der Batterie (5) an den Motor (6) zu steuern, wobei die Steuerschaltung (9) einen Hauptschalter (8) umfasst, der durch einen Benutzer betätigbar ist, sowie einen Zusatzschalter (10, 110), der ebenfalls durch einen Benutzer betätigbar ist; wobei die Steuerschaltung (9) aufweist:

einen aktiven Zustand, in dem die Betätigung des Hauptschalters (8) durch den Benutzer elektrischen Strom an den Motor (6) fließen lässt, um das Schneidelement (2) zu veranlassen, angetrieben zu werden; und

einen inaktiven Zustand, in dem die Betätigung des Hauptschalters (8) keinen elektrischen Strom an den Motor (6) fließen lässt, und der Motor somit das Schneidelement (2) nicht antreibt;

wobei die Betätigung des Zusatzschalters (10, 110) die Steuerschaltung veranlasst, zwischen dem aktiven und dem inaktiven Zustand zu wechseln;

dadurch gekennzeichnet, dass der Zusatzschalter einen Haken (12, 112) umfasst, an dem das Werkzeug aufgehängt werden kann, wobei der Zusatzschalter (10, 110) so angeordnet ist, dass das Aufhängen des Werkzeugs an dem Haken (12, 112) die Steuerschaltung (9) veranlasst, in den inaktiven Zustand zu wechseln.

2. Werkzeug nach Anspruch 1, wobei der Haken (12) schwenkbar an dem Gehäuse montiert ist und eine vorragende Stellung, in der das Werkzeug an dem Haken (12) aufgehängt werden kann, sowie eine eingeklappte Stellung aufweist, in der der Haken (12) relativ zu der der vorragenden Stellung weiter zum Gehäuse hin eingeklappt ist.

3. Werkzeug nach Anspruch 2, wobei das Klappen des Hakens (12) in die eingeklappte Stellung die Steuerschaltung (9) veranlasst, sich in den aktiven Zustand zu bewegen.

4. Werkzeug nach einem der vorhergehenden Ansprüche, wobei der Haken (112) an dem Gehäuse (101) mittels eines Lastsensors (115) montiert ist, wobei der Zusatzschalter (110) die Steuerschaltung (9) veranlasst, in den inaktiven Zustand zu wechseln, wenn die Last an dem Haken (112) durch den Lastsensor (115) einen vorbestimmten Grenzwert überschreitet.

5. Werkzeug nach einem der vorhergehenden Ansprüche, wobei das Werkzeug eine Kettensäge oder ein Heckenschneider ist.

6. Werkzeug nach einem der vorhergehenden Ansprüche, wobei die Steuerschaltung (9) so angeordnet ist, dass der Hauptschalter (8) und der Zusatzschalter (10, 11, 110) in Reihe liegen.

7. Werkzeug nach einem der vorhergehenden Ansprüche, wobei die Steuerschaltung (9) so angeordnet ist, dass sie in den inaktiven Zustand eintritt, wenn der Hauptschalter (8) für eine vorbestimmte Zeitperiode nicht aktiviert wird.

8. Werkzeug nach Anspruch 7, wobei die Steuerschaltung (9) so angeordnet ist, dass eine Betätigung des Zusatzschalters (10, 11, 110), nachdem die Steuerschaltung (9) nach Ablauf der Zeitperiode sich deaktiviert hat, die Steuerschaltung (9) veranlasst, in den aktiven Zustand einzutreten.

Revendications

1. Outil de coupe portatif alimenté par batterie, comprenant : un boîtier (1), un élément de coupe (2) soutenu par le boîtier, un moteur électrique (6) couplé à l'élément de coupe (2) de manière à entraîner l'élément de coupe (2) pour couper, une batterie (5) couplée électriquement au moteur (6) de manière à alimenter le moteur (6) en courant électrique et un circuit de commande (9) agencé pour commander l'alimentation du moteur (6) en courant électrique provenant de la batterie (5),
dans lequel le circuit de commande (9) comprend un commutateur principal (8) pouvant être actionné par un utilisateur et un commutateur auxiliaire (10, 110) pouvant être actionné également par un utilisateur ;
dans lequel le circuit de commande (9) présenté
un état actif dans lequel l'actionnement du commutateur principal (8) par l'utilisateur permet au courant électrique de circuler dans le moteur (6) de manière à amener l'élément de coupe (2) à être entraîné ; et
un état inactif dans lequel l'actionnement du commutateur principal (8) ne permet pas au courant électrique de circuler dans le moteur (6) et par conséquent le moteur n'entraîne pas l'élément de coupe (2) ;
dans lequel l'actionnement du commutateur auxiliaire (10, 110) amène le circuit de commande à commuter entre les états actif et inactif ;
caractérisé en ce que le commutateur auxiliaire comprend un crochet (12, 112) auquel l'outil peut être suspendu, le commutateur auxiliaire (10, 110) étant agencé de sorte que la suspension de l'outil au crochet (12, 112) amène le circuit de commande (9) à passer à l'état inactif.

2. Outil de la revendication 1, dans lequel le crochet (12) est monté de manière pivotante sur le boîtier et a une position en saillie, dans laquelle l'outil peut être suspendu au crochet (12), et une position repliée, dans laquelle le crochet (12) est replié davantage vers le boîtier (1) par rapport à la position en saillie.

3. Outil de la revendication 2, dans lequel l'action consistant à plier le crochet (12) dans la position repliée amène le circuit de commande (9) à passer à l'état actif.

4. Outil de l'une des revendications précédentes, dans lequel le crochet (112) est monté sur le boîtier (101) au moyen d'un capteur de charge (115), le commutateur auxiliaire (110) amenant le circuit de commande (9) à passer à l'état inactif si la charge sur le crochet (112) à travers le capteur de charge (115) dépasse une limite prédéterminée.

5. Outil de l'une des revendications précédentes, qui est une scie à chaîne ou un taille-haie.

6. Outil de l'une des revendications précédentes, dans lequel le circuit de commande (9) est agencé avec le commutateur principal (8) et le commutateur auxiliaire (10, 11, 110) en série.

7. Outil de l'une des revendications précédentes, dans lequel le circuit de commande (9) est agencé pour entrer dans l'état inactif si le commutateur principal (8) n'est pas activé pendant une durée prédéterminée.

8. Outil de la revendication 7, dans lequel le circuit de commande (9) est agencé de sorte que la manipulation du commutateur auxiliaire (10, 11, 110) après que le circuit de commande (9) a été désactivé après l'écoulement de la durée amène le circuit de commande (9) à entrer dans l'état actif.

Drawing