Door actuator

Abstract

 Door actuator consisting of a double-action pneumatic cylinder consisting of two hollow cases inserted one into the other (1,2), each including a pair of spiral grooves (3) turned by 180 degrees and opposite oriented in the cases (1,2) in relation to each other, and of two pairs of carriers slinding inside the grooves, with both grooves (3) of the inner case (1) in the shape of spatial curves whose tangent and the longitudinal axis of the inner case (1) are in the angle α₁, and both grooves (4) of the outer case (2) in the shape of spatial curves whose tangent and the longitudinal axis of the outer case (2) are in the angle α₂, characterized in that both grooves (4) of the outer case (2) are provided by an extension (5) in comparison to grooves (3) of the inner case (1), in the shape of spatial curves whose tangent and the longitudinal axis of the outer case (2) are in the angle of α₃ in relation to each other.

Description

Technical Field of the Invention

[0001] The invention involves door actuator, including but not limited to actuator of doors of transport means, changing the straight movement of the double-action pneumatic cylinder to rotational movement needed for door opening and closing.

State of the Art

[0002] The so far used actuators consist of two hollow cases inserted one into the other, changing the straight movement from the double-action pneumatic cylinder to rotational movement transferred onto the bar connected with the inner case controlling door opening and closing with the help of two opposite-oriented spiral grooves and carriers guided by the grooves. This type of actuator is described for example in document CZ 243175.

[0003] Some known actuators include one pair of spiral grooves, usually longer by the outer case, with this extended part straight, parallel in the axial direction with the case axis, which enables protrusion of the door after closing in the straight direction upwards and allows for its locking with wedged segments against spontaneous opening, for example by the under-pressure resulting from the vehicle movement. Such an actuator is described for example in document CZ 10699 U1. As a result of the door inertia all known actuators, including those with transfer of straight movement to rotational movement with the help of a ball screw, cause a bounce to the door frame, especially in winter or on an uneven ground, causing insufficient tightness of the door and the frame sealing, for the wedged segments of the door not caught in the wedged segments of the frame. Accurate fitting of the door into the frame sealing is only provided for by the wedged segments. The speed of the door closing must therefore be reduced significantly. Other resulting effects include extreme stress exerted on the hinged consoles of the door by the axial forces of the double-action cylinder, not distributed across the spiral groove but acting directly.

Summary of the Invention

[0004] The above-mentioned drawbacks are to a large extent removed by the door actuator that is the subject of the present invention, whose essence is the fact that both grooves of the outer case are provided with extensions in contrast to the inner case grooves in the shape of a spatial curve whose tangent and the longitudinal axis of the outer case are in the angle of α₃ between each other. The extension of the outer case groove in the shape of spatial curve will enable extended smoothness of movement of the door in the final stage of closing, increasing reliability and speed of the closing operation.

Description of Drawings

[0005] The invention is introduced in greater detail in the drawings, Fig. 1 depicting the inner case with two grooves in a partial section, Fig. 2 depicting the unfolded shape of the inner case groove, Fig. 3 depicting the outer case with the extended grooves in a partial section and Fig. 4 depicting the unfolded shape of the outer case groove.

Description of Illustrative Embodiment

[0006] Fig. 1 shows the inner case 1 of the actuator in the shape of a hollow cylinder with two grooves 3 in the coating turned by 180 degrees in relation one to another, with the inner case 1 firmly fixed to the bar 7 controlling the door opening and closing.

[0007] Fig. 2 shows that the shape of the groove 3 is spatial curve whose tangent and the longitudinal axis are in the angle of α₁ in relation to each other.

[0008] Fig. 3 shows the outer case 2 of the actuator, also in the shape of a hollow cylinder, with two grooves 4 in the outer case 2 turned by 180 degrees in relation one to another. The outer case 2 is provided with a flange 6.

[0009] Fig 4 shows that the shape of the groove 4 is spatial curve whose tangent and the longitudinal axis of the outer case 2 are in the angle of α₂ in relation to each other.

[0010] Both grooves 4 are provided with extensions 5 in contrast to the grooves 3 in the inner case 1, in the shape of spatial curves in the angle of α₃ with the longitudinal axis of the outer case 2.

[0011] In the final stage of the closing procedure the door does not only perform straight movement upwards under the wedged segments but also turn by the required angle determined by the construction of the door frame and the sealing. This is allowed by the two grooves in both hollow cases in the shape of spatial curves - most often spirals.

[0012] Both the outer and the inner hollow case have the two grooves turned by 180 degrees in relation to each other. In addition, the grooves of the outer case are oriented opposite the inner case grooves. One of the pair of grooves is extended in the axial direction by a value within the range 1 - 30 mm. This extension, however, is in an angle related to the vertical axis different from the previous section of the curve. This extension is most conveniently implemented in the outer case grooves.

[0013] The following is the description of activity of the actuator that is subject of the present invention in the course of the door closing procedure. The compressed air acting in the bottom part of the pneumatic cylinder exerts force on the piston inside the cylinder and the piston begins to rotate and move straight upwards. With the help of two pairs of carriers installed on one of the pins and conveniently designed as small needle bearings, the moving piston rotates the inner hollow case in relation to the outer hollow case, which is fixed and cannot rotate. The carrier, in our case the needle bearings, begin to roll away in all four grooves of both cases, with the inner case transferring the rotational movement onto the bar controlling the door opening and closing.

[0014] The inner case must be secured against axial shift with a settable reaction force. Mechanical spring is conveniently used for generation of this force. When the carrier hits the end of both grooves of the inner case or the closing door hits a solid obstacle, the piston of the pneumatic cylinder continues to push the whole construction further upwards. After overcoming the axial reaction force the pushing force keeps the inner case in the bottom position, enabled by the extended groove in the outer case. In our case the extended groove is not straight but tilted under a certain angle in relation to the vertical axis. In this stage the control bar of the door moves upwards and the door is pushed into the robber sealing of the frame, adapted for that purpose. At the moment when the resistance of the pressed rubber sealing exceeds the rotation momentum given by distribution of the force across the extended, in our case spiral grooves, or the carriers hit the ends of the extended grooves of the outer case, the process comes to an end. In the process of the door opening the compressed air in the pneumatic cylinder acts above the piston and the whole process is reverted.

[0015] Test have proved that thanks to the design of the groove extension in the outer case in the shape of spatial curve the door does not bounce against the frame in the final stage of the closing, which increases reliability of the door closing function and the speed of the closing procedure. This bounce often causes leaning of the door against the wedged segments from the outside, which makes the wedged segments non-functional and therefore not performing their safety role. Also thanks to the force distribution across the spiral groove the door consoles are exposed to lower stress, which significantly extends the life of the whole door closing system. Thanks to the new construction of the groove the door and the frame are tight and secure enough and so the wedged segments just perform the role of an additional security element. This solution, regarding the simplicity of the construction change of the angle of ascend of the spiral in the extended groove of the outer case, is able to flexibly react to different constructional designs of the door frame and sealing.

Claims

1. Door actuator consisting of a double-action pneumatic cylinder consisting of two hollow cases inserted one into the other (1,2), each including a pair of spiral grooves (3) turned by 180 degrees and opposite oriented in the cases (1,2) in relation to each other, and of two pairs of carriers slinding inside the grooves, with both grooves (3) of the inner case (1) in the shape of spatial curves whose tangent and the longitudinal axis of the inner case (1) are in the angle α₁, and both grooves (4) of the outer case (2) in the shape of spatial curves whose tangent and the longitudinal axis of the outer case (2) are in the angle α₂, characterized in that both grooves (4) of the outer case (2) are provided by an extension (5) in comparison to grooves (3) of the inner case (1), in the shape of spatial curves whose tangent and the longitudinal axis of the outer case (2) are in the angle of α₃ in relation to each other.

Amended claims

Amended claims in accordance with Rule 86(2) EPC.

1. Door actuator consisting of a double-action pneumatic cylinder consisting of two hollow cases inserted one into the other (1,2), each including a pair of spiral grooves (3) turned by 180 degrees and opposite oriented in the cases (1,2) in relation to each other, and of two pairs of carriers sliding inside the grooves, with both grooves (3) of the inner case (1) in the shape of spatial curves whose tangent and the longitudinal axis of the inner case (1) are in the angle α₁, and both grooves (4) of the outer case (2) in the shape of spatial curves whose tangent and the longitudinal axis of the outer case (2) are in the angle α₂, both grooves (4) of the outer case (2) are provided by an extension (5) in comparison to grooves (3) of the inner case (1), in the shape of spatial curves whose tangent and the longitudinal axis of the outer case (2) are in the angle of α₃ in relation to each other, characterized in that the extension of one of the pair of grooves (4) is extended in the axial direction by a value within the range 1 - 30 mm.

Drawing