Linear actuator

Abstract

A linear actuator is described comprising an actuator housing, a driven element moveable at a front end of the linear actuator and a mounting (4) at a rear end of the linear actuator, wherein the mounting (4) comprises two arms (9,10) and an accommodation space (11) between the two arms (9,10). The object underlying the invention is to provide a linear actuator which can easily be mounted with its rear mounting. To this end, at least one arm (9,10) is provided with a lever (12,13) which is rotatable about an axis between an open position and a closed position, wherein in the closed position, an end portion (14,16) of the lever (12,13) at least partly closes an opening (18) between the two arms (9,10) and in the open position makes the opening (18) accessible.

Claims

1. A linear actuator (1) comprising: an actuator housing (2); a driven element (3) movable at a front end of the linear actuator (1); and a mounting (4) at a rear end of the linear actuator (1), wherein the mounting (4) comprises: two arms (9,10); and an accommodation space (11) between the two arms (9,10) having an opening (18), wherein at least one arm (9,10) is provided with a lever (12,13), the lever (12,13) having an end portion (14, 16) at a first end distal to the actuator housing (2), and an actuation portion (15, 17) at a second end proximal to the actuator housing (2), the lever (12,13) is configured to rotate relative to the at least one arm (9, 10) about an axis located between the end portion (14, 16) and the actuation portion (15, 17), wherein the lever (12, 13) is rotatable between an open position and a closed position, and wherein in the closed position, the end portion (14,16) of the lever (12,13) at least partly closes the opening (18) and in the open position makes the opening (18) accessible.

2. The linear actuator according to claim 1, wherein the lever (12,13) is a two-arm lever, wherein in the open position, the actuating portion (15,17) protrudes into the accommodation space (11).

3. The linear actuator according to claim 1, wherein the lever (12,13) is secured in the closed position by means of a snap connection.

4. The linear actuator according to claim 3, wherein the snap connection is a releasable snap connection.

5. The linear actuator according to claim 4, wherein the snap connection comprises a wedge arrangement (21,22) at the lever (12,13) and a stop arrangement (27) at the arm (9,10), wherein engagement of the wedge arrangement (21,22) and the stop arrangement (27) prevents rotation of the lever (12,13) about the axis.

6. The linear actuator according to claim 5, wherein the wedge arrangement (21,22) and the stop arrangement (27) are movable relatively to each other in a direction perpendicular to the longitudinal axis of the inner tube (3).

7. The linear actuator according to claim 5, wherein the wedge arrangement (21,22) is located on a resilient part of the lever (12,13).

8. The linear actuator according to claim 5, wherein the wedge arrangement comprises at least two wedges (21,22), each wedge (21,22) being arranged on a resilient branch (19,20) of the lever (12,13), wherein the resilient branches (19,20) can be pressed towards each other to move the wedges (21,22) out of engagement with the stop arrangement (27).

9. The linear actuator according to claim 1, wherein the mounting (4) comprises a fixture housing, wherein the fixture housing comprises two housing parts and the lever (12,13) is mounted between the two housing parts.

10. The linear actuator according to claim 1, wherein each arm (9,10) comprises a lever (12,13).

11. The linear actuator according to claim 1, wherein in the closed position at least in a region of the accommodation space (11) opposite the opening (18), the lever (12,13) extends into the accommodation space (11) over the arm (9,10).

12. The linear actuator according to claim 11, wherein the lever (12,13) at least at a surface facing the accommodation space (11) is made of a material having a lower friction coefficient than the material of the arm (9,10).

13. The linear actuator according to claim 1, wherein the surface of the arm (9,10) facing the accommodating space (11) has a lower friction coefficient than the lever (12,13) at least on a surface facing the accommodation space (11).

Description

(1) A preferred embodiment of the invention will now be described in more detail with reference to the drawing, wherein:

(2) FIG. 1 is a perspective view of linear actuator,

(3) FIG. 2 is a top view of the linear actuator before insertion of a shaft,

(4) FIG. 3 is a top view of the linear actuator during insertion of a shaft,

(5) FIG. 4 is a top view of the actuator with inserted shaft,

(6) FIG. 5 is a side view of the actuator before insertion of the shaft,

(7) FIG. 6 is a side view of the actuator during insertion of the shaft,

(8) FIG. 7 is a side view of the linear actuator with inserted shaft,

(9) FIG. 8 is a perspective view of the mounting,

(10) FIG. 9 is an exploded view of the mounting, and

(11) FIG. 10 is a perspective view of the linear actuator.

(12) In all figures, the same elements have the same reference numerals.

(13) FIG. 1 shows a linear actuator 1 comprising a console 2, a driven element 3 moveable at a front end of the console 2 and a mounting 4 at a rear end of the console 2.

(14) The driven element 3 is a so-called “inner tube” which is telescoping inside an outer tube 5 connected to the console 2. An electric motor 6 is connected to the console 2 and drives a spindle which is arranged in the console 2 and the outer tube 5. The driven element 3 is connected to a spindle nut which is threaded on the spindle. The spindle nut is secured against rotation. When the electric motor 6 drives the spindle, the spindle nut and consequently the driven element 3 is driven out of or into the outer tube 5. The direction of movement of the driven element 3 depends on the direction of rotation of the electric motor 6.

(15) The driven element 3 is connected to a front mounting 7 which can be used for connecting the driven element 3 to e.g. a section of a bed.

(16) The mounting 4 at the rear end of the console 2, which is often referred to as “rear mounting”, is used for connecting the linear actuator 1 to a shaft 8. The shaft 8 can be a part of a bed in which the linear actuator 1 is used. However, the shaft 8 can be part of any other item or article of furniture in which the linear actuator 1 is used.

(17) The mounting 4 comprises two arms 9,10 defining an accommodating space 11 there between. The accommodating space 11 has an opening 18 extending between the free ends of the arms 9,10. In the present embodiment, each arm 9,10 is provided with a lever 12,13. The lever 12 is a two-arm lever, one end of which is an end portion 14 and the other end constitutes an actuation portion 15. The lever 12 is rotatable about an axis y located between the end portion 14 and the actuation portion 15 (see FIG. 9). It extends perpendicular to the plane of the drawing of FIGS. 2-4, or parallel to the longitudinal axis of the shaft 8.

(18) In the same way, the lever 13 is a two-arm lever, one end of which is an end portion 16 and the other end constitutes an actuation portion 17.

(19) When the levers 12,13 are in the position shown in FIG. 2, the two actuation portions 15,17 protrude into the accommodation space 11. This position is called “the open position” since the accommodation space 11 is open to the outside so that the shaft 8 can be inserted through the opening 18 (FIGS. 3 and 4). As can be seen in FIG. 2, the shaft 8 touches the free ends of the arms 9,10.

(20) It should be mentioned, that the distance between the two arms 9,10 at the opening 18 is slightly smaller than the diameter of the shaft 8 so that the arms 9,10 flex slightly outwards or away from each other when the shaft 8 is inserted into the accommodation space 11.

(21) When the shaft 8 is pushed further into the accommodation space 11, it comes into contact with the actuation portions 15,17 of the levers 12,13 (FIG. 3). Upon further movement of the shaft 8 into the accommodation space 11, the lever 12 is rotated clockwise and the lever 13 is rotated counter clockwise (with respect to the view shown in FIG. 3) and the two end portions 14,16 move towards each other reducing the opening 18 of the accommodation space 11 such that the shaft 8 cannot move out of the accommodation space 11.

(22) In the closed position shown in FIG. 4, the levers 12,13 are secured by means of a snap connection. In the present embodiment, this is a releasable snap connection.

(23) This connection will be described in connection with FIGS. 5 to 7.

(24) FIG. 5 shows a side view corresponding to the top view of FIG. 2, FIG. 6 shows a side view corresponding to the top view of FIG. 3, and FIG. 7 shows a side view corresponding to the top view of FIG. 4.

(25) In FIGS. 5 to 7 the lever 13 of the arm 10 is shown. The lever 13 comprises two spring branches 19,20. Each spring branch 19,20 has a wedge 21,22. The arm 10 is made of two-arm parts 10a,10b. Each arm part 10a,10b is furnished with a stop 27 at the end adjacent to the opening 18. At the end of each spring branch 19,20, a grip 23,24 is arranged. The two spring branches 19,20 can be pressed together by using two fingers.

(26) When the shaft 8 is pushed into the accommodation space 11 and the levers 12,13 are rotated to close or reduce the opening 18 of the accommodation space 11, the wedges 21,22 have to pass through a gap 25 between the two parts 10a,10b of the arm 10. During this movement, the two spring branches 19,20 are pressed together so that the wedges 21,22 can pass the two parts 10a,10b of the arm 10. When the shaft 8 has been completely inserted into the accommodation space 11 (FIG. 7) the spring arms 19,20 flex back into their initial position and the rear side 26 (FIG. 2) of the wedges 21,22 comes to rest behind a stop arrangement which is constituted by the two-part 10a,10b of the arm 10. Such a stop 27 of the stop arrangement is shown in FIGS. 2 and 3.

(27) It is apparent that the levers 12,13 cannot be opened as long as the wedge 21, more precisely the rear side 26 of the wedge 21, rests against the stop 27. However, when the two grip portions 23,24 are pressed together, the rear side 26 of the wedges 21,22 will disengage from the stops 27, and the levers 12,13 can be turned or rotated in the open position shown in FIG. 2.

(28) As can be seen in FIGS. 5-7 the lever 13 is arranged in the space between the two-part 10a,10b of the arm 10 in a direction parallel to the longitudinal axis of the inner and outer tube, 3,5. The spring branches 19,20 are located in the gap 25 of the lever 13 at least when the lever 13 is in the closed position. The embodiment of the lever 12, corresponds to the lever 13.

(29) In the closed position shown in FIGS. 4 and 7, the actuation portion 15,17 of the levers 12,13 can extend slightly into the accommodation space 11 defined by the arms 9,10. The actuation portions 15,17 only extend a fraction of a millimeter (for example, 0,2, 0,3, 0,4, or 0.5 mm) into the accommodating space 11, and are therefore not visible in FIG. 4. However, in the closed position, the shaft 8 only contacts the actuating portions 15,17 of the levers and the remaining inner surface of the arms 9, 10. When the levers 12,13 are made from a material which has a lower friction coefficient to the shaft 8 than the material of the arms 9, 10, noise can be reduced or totally avoided when the whole linear actuator 1 rotates around the shaft or vice versa.

(30) As can be seen in particular in FIG. 9, the mounting 4 comprises two housing parts. The two housing parts form the parts 9a,9b,10a,10b of the arms 9, 10. The levers 12,13 are mounted between the two housing parts.