LINEAR DRIVE WITH CLUTCH

Abstract

A linear drive having a transmission housing and an electric motor which is accommodated in the transmission housing and drives a shaft with a worm. The shaft meshes with a worm gear which can be non-rotatably connected by way of a clutch to a spindle holder non-rotatably connected to a spindle. The clutch is biased by a spring and is adjustable by means of a clutch actuation. To permit simple and rapid operation of the clutch it is proposed that the clutch actuation includes a slide element which bears against the clutch and which is arranged non-rotatably but axially displaceably in relation to the clutch. A rotary element which is axially fixed but rotatable about an axis of rotation engages the slide element at an outside that faces away from the clutch. Run-on bevels of complementary configuration are provided between the slide element and the rotary element. The rotary element is actuable by way of a pulling element.

Claims

1-16. (canceled)

17. A linear drive comprising: a transmission housing, an electric motor which is accommodated with the transmission housing and drives a shaft with a worm which, in turn, meshes with a worm gear which is non-rotatably connectable by a clutch to a spindle holder to which there is non-rotatably connected a spindle on which runs a spindle nut which is adjustable in a guide tube longitudinally displaceably between a retracted rear end position and an extended front end position and is connected to a lift tube, wherein the clutch is biased by a spring, wherein the clutch is displaceable by a clutch actuation between a coupled position in which the clutch non-rotatably connects the worm gear to the spindle holder and an uncoupled position in which the clutch releases the spindle holder, wherein the clutch actuation includes a slide element which bears against the clutch and which is arranged non-rotatably but axially displaceably in relation to the clutch and that a rotary element which is axially fixed but rotatable about an axis of rotation engages the slide element at an outside facing away from the clutch, that run-on bevels of a complementary configuration are provided between the slide element and the rotary element, and that there is provided a pulling means with which the rotary element is actuable.

18. The linear drive as set forth in claim 17, wherein the clutch is in a form of a clutch sleeve.

19. The linear drive as set forth in claim 18, wherein the slide element and the rotary element are of a ring-shaped configuration or sleeve-shaped configuration.

20. The linear drive as set forth in claim 19, wherein the rotary element is in a form of a rotary ring and the rotary ring externally has two pulling means holders in diametrally opposite relationship.

21. The linear drive as set forth in claim 17, wherein at least one Bowden cable holder is rotatably fitted to the rotary element.

22. The linear drive as set forth in claim 22, wherein the rotary element has a recess for the at least one Bowden cable holder.

23. The linear drive as set forth in claim 17, wherein the clutch actuation is arranged in a fork head.

24. The linear drive as set forth in claim 23, wherein the fork head has a receiving connecting piece extending from an end wall of the fork head in an opposite direction to forks provided on the fork head.

25. The linear drive as set forth in claim 23, wherein the fork head has a feed opening for a connection of a Bowden cable holder.

26. The linear drive as set forth in 23, wherein the fork head has two diametrally oppositely disposed entry connecting pieces to receive Bowden cable holders which project in diametrally opposite relationship tangentially laterally from a peripheral surface of the fork head.

27. The linear drive as set forth in claim 17, wherein the spindle holder has a bearing seat on which an inner race of a bearing sits, an outer race of the bearing sits in a bearing seat of a bearing holder which mounts the bearing in a fork head or in the transmission housing and that the bearing holder is arranged within the clutch actuation.

28. The linear drive as set forth in claim 27, wherein the bearing seat of the bearing holder includes an axial abutment acting axially on the bearing.

29. The linear drive as set forth in claim 27, wherein the bearing seat of the bearing holder has a bearing step against which the outer race of the bearing bears radially externally and axially at an end.

30. The linear drive as set forth in claim 27, wherein the bearing seat is interrupted to form bearing fingers which are formed peripherally separatedly from each other.

31. The linear drive as set forth in claim 30, wherein the slide element has bearing finger recesses which are provided at an outside facing towards the rotary element to receive the bearing fingers and into which the bearing fingers engage.

32. The linear drive as set forth in claim 31, wherein the bearing holder has six peripherally spaced bearing fingers which engage into six slot-like bearing finger recesses of complementary configuration at the outside of the slide element.

33. The linear drive as set forth in claim 27, wherein the bearing holder has a connecting portion to connect to the fork head or the transmission housing.

34. The linear drive as set forth in claim 33, wherein the connecting region of the bearing holder has a plurality of transverse struts which extend transversely relative to a longitudinal axis of the bearing holder, with intermediate spaces provided between them, into which pins or projections at an inside of an end of the fork head engage in an installed position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Finally in relation to a plurality of identical components or elements, for reasons of clarity, only a respective one is denoted by a reference numeral.

[0049] In the drawings:

[0050] FIG. 1 shows an isometric front view of a linear drive according to the invention,

[0051] FIG. 2 shows an enlarged isometric front view of the rear end of the linear drive with the housing cover taken off and the fork head removed,

[0052] FIG. 3 shows an isometric exploded view of the arrangement including worm gear, clutch and spindle holder,

[0053] FIG. 4 shows an enlarged perspective plan view of the arrangement shown in FIG. 3 in the uncoupled position (disengaged),

[0054] FIG. 5 shows the plan view of the arrangement as shown in FIG. 4 in the coupled state,

[0055] FIG. 6 shows an isometric enlarged view of the clutch actuation according to the invention with the fork head removed,

[0056] FIG. 7 shows an enlarged isometric plan view of the arrangement including worm gear, clutch, spindle holder and the clutch actuation in the coupled position,

[0057] FIG. 8 shows an enlarged isometric view of the arrangement of FIG. 7 from the rear in the uncoupled position,

[0058] FIG. 9 shows an enlarged longitudinal section of the arrangement including worm gear, clutch, spindle holder, bearing, bearing holder and clutch actuation including slide sleeve and rotary sleeve,

[0059] FIG. 10 shows a longitudinal section of the linear drive of FIG. 10 through the center of the guide tube, and

[0060] FIG. 11 shows an isometric side view of the fork head 10 from the rear, adapted to receive the clutch actuation.

DETAILED DESCRIPTION

[0061] Referring to FIG. 1 the linear drive thus substantially comprises a two-part transmission housing 2, a motor housing 4 accommodated therein, with an electric motor in the motor housing and a guide tube 6 which extends in the longitudinal direction of the linear drive and in which a lift tube 8 is longitudinally displaceably accommodated and is displaceable between a retracted end position shown in FIG. 1 and a completely extended end position.

[0062] Respective fork heads 10, 12 are fixed at the front end of the lift tube and at the rear end of the housing. The linear drive can be fixed with those fork heads 10, 12 between two components which are displaceable relative to each other, for example for displacement of the pivotable head and foot ends of a bed with respect to a stationary frame. Preferably in that case the rear fork head 10 is connected to a transverse strut on the frame of the bed and the front fork head 12 is connected pivotably with a transverse strut to the foot or head portion fitted to the frame. Therefore by extension and retraction of the lift tube 8 in relation to the stationary guide tube 6 the foot or head portion is pivoted in relation to the stationary frame which forms a frame plane, that is to say it is lifted out of the frame plane.

[0063] The transmission housing 2 is divided or divisible and includes a rear housing portion 2a and a housing cover 2b which is connected thereto at a joining flange, a sealing groove being provided on the flange.

[0064] The rear housing portion 2a has a cylindrical receiving connecting piece for receiving the motor housing 4, that therefore extends transversely to the longitudinal direction of the linear drive.

[0065] In the present case therefore the motor housing 4 extends transversely to the longitudinal axis of the linear drive.

[0066] As can be seen from FIG. 1 the fork head 10 has a receiving connecting piece 10b which is provided by an end wall of the fork head 10 in the opposite direction to the fork head and from which entry connecting pieces 10d, 10e for receiving the Bowden cable holders 26, 28 extend tangentially relative to the outer peripheral surface and transversely relative to the longitudinal axis of that receiving connecting piece 10b, or from which the Bowden cable holders 26, 28 project, more specifically a respective Bowden cable holder 26 upwardly and the other Bowden cable holder 28 in the opposite direction downwardly relative to the first one.

[0067] FIG. 2 shows an enlarged perspective front view of the transmission arranged in the transmission housing 2, with the housing cover 2b and the fork head 10 removed. The shaft driven by the electric motor with the spindle 14 thereon projects transversely into the transmission housing and meshes with a worm gear 16 which has a splined shaft connection 16a formed in one piece laterally beside the actual worm gear with the tooth flanks. Arranged on that splined shaft connection 16a is a compression spring 18 which acts on a clutch sleeve 20 which is carried non-rotatably and longitudinally displaceably on the splined shaft connection 16a and which internally has a splined shaft structure complementary to that of the splined shaft connection 16a.

[0068] Actuation of the clutch sleeve 20 for disengagement in an emergency situation, that is to say for emergency release, is effected by way of the clutch actuation according to the invention, in the present case including a slide sleeve 22 which acts internally on the clutch sleeve 20 and is arranged axially displaceably but non-rotatably and on which the rotatable but axially fixed rotary sleeve 24 externally acts.

[0069] The two Bowden cable holders 26, 28 are rotatably connected at the outer end of that rotary sleeve 24 in diametrally opposite relationship and extending tangentially relative to the periphery of the rotary sleeve. Steel cables with terminal cable thimbles (not shown) can be inserted or snap-fitted into those Bowden cable holders 26, 28.

[0070] FIG. 3 shows an exploded view of the assembly comprising the worm gear 16 with the splined shaft connection 16a formed thereon and the compression spring 18 carried on that splined shaft connection 16a. In addition pushed on to the splined shaft connection 16a is the clutch sleeve 20 which has an inner splined shaft structure of a complementary configuration to that of the splined shaft connection 16a.

[0071] At the end the hollow-cylindrical spindle holder 30 in which the spindle 32 is non-rotatably accommodated is fitted into the outer rear end of the splined shaft connection 16a. At the rear end which therefore faces away from the clutch sleeve 20 the spindle holder 30 has a splined shaft flange 30b which projects outwardly radially from the hollow-cylindrical peripheral surface of the central spindle connection 30a for non-rotatably receiving the spindle 32 and at the inside of which, that is directly directed towards the clutch sleeve 20, there is also a splined shaft structure of a complementary configuration to the shaft structure at the splined shaft connection 16a of the worm gear 16.

[0072] FIG. 4 shows an enlarged plan view of those FIG. 3 elements in the uncoupled position in which therefore the clutch sleeve 20 releases the splined shaft flange 30b of the spindle holder 34 for providing for the desired free-running movement of the spindle 36.

[0073] FIG. 5 in contrast shows the clutch sleeve 20 in the coupled position in which therefore the sleeve 20 non-rotatably connects the splined shaft connection 16a of the worm gear to the spindle holder 34, that is to say it is pressed by the compression spring 18 on to the splined shaft flange 30b of the spindle holder 30.

[0074] The slide sleeve 22 is fixed non-rotatably but displaceably in the longitudinal direction of the clutch arrangement and therefore acts with the internal end face on the clutch sleeve 20 to uncouple same. The slide sleeve 22 has a plurality of, in the present case 6, axially projecting run-on bevels 22a which are peripherally equidistantly spaced at the outer end face which is therefore facing towards the rotary sleeve 24. At the inside facing towards the slide sleeve 22 the rotary sleeve 24 has run-on bevels 24a of the rotary sleeve 24, that are of a complementary configuration to those run-on bevels 22a of the slide sleeve, so that in the installed position the rotary sleeve 24 and the slide sleeve 22 bear against each other or engage into each other so that the end faces of the slide sleeve 22 and the rotary sleeve 24 bear against each other in planar relationship in the rest position. Rotation of the rotary sleeve 24 about the longitudinal axis in the clockwise direction therefore provides that the complementary run-on bevels 22a, 24a run against each other and thus cause axial displacement of the slide sleeve 22. The slide sleeve 22 bears with its inner end face against the end face of the clutch sleeve 20 and is of such a geometrical configuration that at the same time it projects beyond the splined shaft flange 34b of the spindle sleeve 34 or internally engages same.

[0075] Referring to FIG. 6 at the rear outer end face the rotary sleeve 24 in diametrally opposite relationship has two recesses 24b into which the flat arms 26a, 28a of the Bowden cable holders 26, 28 can be so inserted that the external surface of those arms terminates with the external end face of the rotary sleeve 24 and the rotary sleeve 24 thus terminates in planar relationship with the end face of the fork head 10, at which the forks are externally arranged. The arms 26a, 28a of the Bowden cable holders 26, 28 are connected rotatably by way of pins 24c to the end of the rotary sleeve 24, as can be particularly clearly seen from the enlarged view in FIG. 6.

[0076] FIG. 7 shows the clutch actuation in the coupled rest position in which the slide sleeve 22 bears externally against the rotary sleeve 24, wherein the run-on bevels 22a, 24a of the slide sleeve 22 and the rotary sleeve 24 bear against each other over the full area so that the slide sleeve 22 and the rotary sleeve 24 bear against each other at their ends without any spacing.

[0077] FIG. 8 shows the arrangement of FIG. 7 however in the uncoupled emergency position after rotation of the rotary sleeve 24 in the counter-clockwise direction by a Bowden cable holder 26, 28 so that the run-on bevel surfaces 22a, 24a ran against each other and the slide sleeve 22 was displaced axially inwardly to the clutch sleeve 20.

[0078] In that case the slide sleeve 22 engages over the splined shaft flange 30b of the spindle holder 30 externally and is displaced over same.

[0079] FIG. 9 shows a longitudinal section of the arrangement including the worm gear, the slide sleeve 20 arranged on the splined shaft connection 16a of the worm gear 16, the spindle holder 30 fitted into the rear end of worm gear 16, the rolling bearing 34 which is fitted on the rear bearing seat 30c of the spindle holder 30 and which is externally embraced by the bearing seat of the bearing holder 36.

[0080] At the rear end remote from the clutch sleeve 20 the slide sleeve 22 includes six peripherally equally spaced bearing finger recesses 22b into which the complementary bearing fingers 36a of the bearing holder engage or fit. The peripherally equidistantly spaced bearing fingers 36a form the peripheral bearing seat which defines an axial abutment rearwardly and a radial abutment outwardly. In the installed position the bearing fingers 36a terminate with the outside of the slide sleeve 22 or fit in the complementary bearing finger recesses 22b of the slide sleeve 22.

[0081] A connecting portion rearwardly adjoins the bearing seat of the bearing holder 36, that is formed by the bearing fingers 36a. The connecting portion is of a reduced outside diameter with respect to the bearing seat and in the present case has a plurality of transverse struts 36a extending transversely relative to the longitudinal axis of the bearing holder, with intermediate spaces formed between them, into which in the installed condition projections engage into the fork head at the inside of the end of the fork head and thus fix the bearing holder 36.

[0082] FIG. 10 shows an enlarged longitudinal section of the linear drive through the longitudinal axis of the guide tube 6 and the lift tube 8. It can be clearly seen here that the fork head 10 includes a rear end wall, from which two fixing legs for receiving a bar or the like extend outwardly. In the opposite direction that fork head includes an integrally formed hollow-cylindrical receiving connecting piece 10b which is adapted in length for embracingly receiving the clutch actuation and the clutch sleeve 20. Externally that receiving connecting piece 10b has outwardly projecting ribs 10c which are spaced from each other in the longitudinal direction of the receiving connecting piece 10b and engage into complementary grooves or channels at the inside of the rear end of the transmission housing 2 for positively locking connection or alternatively for latching connection of the fork head 10 to the rear end of the transmission housing 2.

[0083] The transmission thus drives the spindle 14 with a trapezoidal thread, on which a spindle nut 38 runs between the rear retraction position shown in FIG. 10 and an extended extension position in which the lift tube 8 with the front fork head 10 is extended completely from the guide tube 6.

[0084] FIG. 11 shows an isometric side view of the fork head 10 from the rear, adapted to receive the clutch actuation. The fork head 10 includes an end wall 10g which extends transversely to the longitudinal axis of the fork head 10 and from which two forks 10d, 10e extend rearwardly and from which the hollow-cylindrical receiving connecting piece 10b extends in the opposite direction to those forks 10d, 10e, the connecting piece 10b having a plurality of ribs formed on the external peripheral surface thereof in mutually spaced relationship. Beside same it is also possible here to particularly clearly see the entry connecting piece 10f, the longitudinal axis of which extends transversely to the longitudinal axis of the receiving connecting piece 10b tangentially to the outer peripheral surface thereof and into which the Bowden cable holder 26 can be fitted, which is connected rotatably by way of the arm 26 to the rotary ring 24 of the clutch actuation.

LIST OF REFERENCES

[0085] 2 transmission housing [0086] 2a rear housing cover [0087] 4 motor housing [0088] 6 guide tube [0089] 8 lift tube [0090] 10, 12 fork head [0091] 10a projection [0092] 10b receiving connecting piece [0093] 10c ribs [0094] 10d, 10e forks [0095] 10f entry connecting piece [0096] 10g end wall [0097] 14 spindle [0098] 16 worm gear [0099] 16a splined shaft connection [0100] 18 compression spring [0101] 20 clutch sleeve [0102] 22 slide sleeve [0103] 22a run-on bevel [0104] 22b bearing finger recesses [0105] 24 rotary sleeve [0106] 24a run-on bevel [0107] 24b recess [0108] 26 cable holder [0109] 26a arm [0110] 28 cable holder [0111] 28a arm [0112] 30 spindle holder [0113] 30a spindle connection [0114] 30b splined shaft flange [0115] 30c bearing seat [0116] 32 spindle [0117] 34 rolling bearing [0118] 36 bearing holder [0119] 36a bearing finger [0120] 36b transverse strut [0121] 38 spindle nut