WO2018041295A1

WO2018041295A1 - Linear actuator

Info

Publication number: WO2018041295A1
Application number: PCT/DE2017/100653
Authority: WO
Inventors: Kilian Marsing; Simon Mersmann; Hartmut Krehmer; Jochen Rosenfeld
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2016-09-02
Filing date: 2017-08-02
Publication date: 2018-03-08
Also published as: CN109641499B; DE102016216597B3; CN109641499A

Abstract

The invention relates to a linear actuator (1), in particular for adjusting the height of a chassis, comprising two assemblies (2, 3) which can be moved linearly relative to each other and a locking ring (9) which can be rotated relative to the assemblies (2, 3), which has switching cams (10) provided for interacting with a ramp ring (16), and which is designed to receive an axial force acting between the assemblies (2, 3) in at least one locking position. The linear actuator (1) additionally comprises a spring (11) which loads the locking ring (9) in the axial direction and by means of which the locking ring (9) is pressed against its axial bearing point on one of the assemblies (2), whereby an unintended rotation of the locking ring (9) is prevented during a switching process.

Description

linear actuator

The invention relates to a linear actuator, which can be used in a device for height adjustment of a vehicle body.

A device for height adjustment of a vehicle body is known for example from DE 10 2014 215 420 A1. Further such devices are known from the documents DE 10 2014 206 142 A1 and WO 2015/021980 A1. The known devices have locking devices which allow a locked height adjustment at two or three different levels. The locking devices comprise in each case three different locking components, namely a guide sleeve, also referred to as a bell or shell, a locking ring and a ramp ring, also referred to as a switching ring. The locking ring has a plurality of locking cams, which can engage in locking pockets which extend in the longitudinal direction, that is, in the axial direction in the guide sleeve. Different lengths of different locking pockets in this case correspond to different height settings of the known devices. The ramp ring is configured to rotate the locking ring to allow its interaction with various locking pockets. Overall, the known devices allow switching between different switching positions - here: height settings - after the so-called ballpoint pen principle.

The invention has for its object to provide a relation to the cited prior art further developed linear actuator, which is characterized by a particularly favorable ratio between reliability, even under the typical load in the motor vehicle, especially vibration loads, space requirements and ease of installation. This object is achieved by a linear actuator with the features of claim 1. The linear actuator has in known per se basic structure two relatively mutually linearly adjustable modules, wherein in the case of installation of the linear actuator in an adjustable chassis of a motor vehicle, one of the modules with a vehicle body and the other module can be connected to a wheel. In order to lock the linear actuator in defined positions, a relative to both modules rotatable locking ring is provided which is axially mounted on one of the modules and having a plurality of control cams. These switching cams cooperate with a guide sleeve, which is held on the assembly which has no locking ring. The rotation of the locking ring during switching operations by means of a likewise attributable to the linear actuator ramp ring. According to the invention, the locking ring is loaded by the force of a spring in the axial direction, wherein the spring force abuts the locking ring against the one assembly on which the locking ring is axially mounted. This is in particular an assembly comprising a spindle. Upon rotation of the ramp ring, the locking ring can be at least slightly displaceable in the axial direction. In any case, the springing unintentional rotation of the locking ring is prevented during switching operations.

The springing of the locking ring against the ramp ring, provided that at the same time a displacement of the locking ring in the axial direction, based on the matching with the longitudinal axis of the linear actuator center axis of the locking ring, means that the locking ring can take two different, defined axial positioning: On the one hand Locking ring be pressed by the force of the spring to the surface of the ramp ring or the surface of a firmly connected to the ramp ring member. In this state, no unwanted rotations of the locking ring occur even with vibration loads. On the other hand, the locking ring can be lifted by the ramp ring from a bearing surface which is formed on the ramp ring or a fixed part connected to the ramp ring part, which facilitates the rotation of the locking ring during switching operations. The invention is based on the consideration that the locking ring of a linear actuator must be rotatable relative to both relatively displaceable but non-rotatable assemblies, but always has to maintain a defined axial position in relation to one of the assemblies. This means that the locking ring must be inserted immovably between two components of one of the two modules, at the same time a rotation of the locking ring is to be given. A smooth rotatability is eliminated because the locking ring could otherwise turn unintentionally. On the other hand, a sluggish twistability of the locking ring is disadvantageous in that it requires a high drive torque for reliable rotation.

This conflict of objectives is resolved in an advantageous embodiment in that it is purposefully removed from a non-displaceable mounting of the locking ring in one of the modules. Rather, the locking ring is rotatably mounted in such o-on one of the modules that in a first axial positioning of the locking ring whose rotation is neither desired nor done unintentionally and in a second axial positioning a smooth rotation of the locking ring is possible. For this purpose, a small displacement of the locking ring is sufficient. Preferably, the maximum displacement of the locking ring measured in the axial direction of the linear actuator is not more than 10%, for example between 2% and 10%, of the width of the locking ring measured in the same direction. According to an alternative embodiment, there is no significant displacement of the locking ring. The springing of the locking ring provides in this case for a given in each operating condition defined braking torque, which prevents unintentional rotation of the locking ring, especially during switching operations.

In the spring, which acts on the locking ring with an axial force, it is preferably a corrugated spring. With regard to the use of corrugated springs in various environmental constructions is exemplified on the documents

DE 84 22 430 U1 and DE 10 2014 007 866 B4. In principle, at the beginning of tion of the locking ring and an arrangement of a plurality of springs, such as leaf springs, disc springs or coil springs, usable.

According to an advantageous embodiment of the linear actuator comprises a stop element, which is located on that module on which is not the locking ring. The stop element acts as block protection and ensures that the spring does not go to block even in the operating state of the linear actuator in which it is maximally compressed. The stop element preferably has a sleeve shape, wherein a radially inwardly pointing web is formed on a cylindrical portion. An end face, that is to say a circular disk-shaped surface, together with an inner wall or a part of the inner wall of the cylindrical section constitutes a boundary of an annular space in which the spring, in particular corrugated spring, is accommodated.

On the end face of the locking ring, which faces away from the spring, there is preferably a sliding bearing surface which is formed by a component fixedly connected to the ramp ring or by the ramp ring itself. If the locking ring pressed by the spring to the sliding bearing surface, so the locking ring is thus held in constant angular position.

The relative displacement between the two modules of the linear actuator is preferably carried out by means of a screw drive, in particular a ball screw. In general, the linear actuator, for example, electrically, hydraulically or pneumatically driven.

The linear actuator is suitable for use in a passenger car as well as for use in a commercial vehicle such as a truck, an agricultural vehicle or a construction machine. Likewise, the device is usable in stationary applications. An embodiment of the invention will be explained in more detail with reference to a drawing. Herein show:

FIG. 1 perspective view of components of a linear actuator;

Figure 2 is a sectional view of a detail of the linear actuator in a first

Switching state,

FIG. 3 is a representation analogous to FIG. 2 of the linear actuator in a second embodiment

Switching state.

A generally designated by the reference numeral 1 linear actuator is provided as a suspension component for height adjustment of a vehicle body of a motor vehicle.

The linear actuator 1 is composed of two modules 2, 3, which are linearly displaceable against each other and thus allow a level adjustment of the motor vehicle. The common longitudinal axis of the two assemblies 2, 3 is denoted by L and arranged substantially vertically in the vehicle.

The first assembly 2, which is referred to without limitation of generality as the lower assembly, has a threaded spindle 4, which is linearly adjustable relative to the spindle nut by means of a spindle nut, not shown, which is attributable to the second, upper assembly 3. The threaded spindle 4 and the associated spindle nut are components of a screw drive 5, namely ball screw, which converts a gear as a linear actuator within the linear actuator 1 in a rotation. The drive of the screw 5, for example, in the form of a direct drive, that is gearless, or via a belt drive or via a gear transmission. The threaded spindle 4 surrounds a support element 6, which is like the threaded spindle 4 tubular and the lower assembly 2 attributable. On an end face of the spindle nut 5 is an annular sliding bearing element 7, which is rotatably connected to the assembly of threaded spindle 4 and support member 6. This slide bearing element 7 forms a bearing surface 8 for a locking ring 9. The locking ring 9 has three radially outwardly directed switching cam 10, which can lock in different positions on the upper assembly 3. In the locked positions in each case an axial displacement between the modules 2, 3 is blocked in one direction, whereby the effective between the assemblies 2, 3 ball screw 5 is mechanically relieved.

The locking ring 9 is pressed by a spring 1 1, namely wave spring in the direction of the threaded spindle 4. The corrugated spring is arranged in an annular space 12, which is bounded radially inwardly by the cylindrical peripheral surface of the support element 6 and on an end side directly by the locking ring 9. On the opposite end face, that is, the end facing away from the locking ring 9, the annular space 12 is bounded by a web 13 of a stop element 14. The upper assembly 3 zuzuschchnende stop member 14 is designed to be annular overall, wherein a cylindrical portion of the stop member 14 is denoted by 15. At the cylindrical, that is sleeve-shaped portion 15 of the stop element 14, the web 13 is integrally formed pointing radially inwardly. Here, the cylindrical portion 15 protrudes in both axial directions, that is along the longitudinal axis L, beyond the web 13, whereby a cross section of the stop element 14 has a - in the present case asymmetric - T-shape. An end face of the cylindrical section 15 - in the arrangement according to FIGS. 1 to 3 on the lower side of the stop element 14 - is intended to abut against an end face of the locking ring 9 in the outer region, while the spring 1 1 radially within this contact zone between the stop element 14 and the locking ring 9 is arranged. Even with the maximum possible compression of the spring 11, that is to say when the overall annular stop element 14 abuts the locking ring 9, the spring 11 is not blocked. The stop element 14 thus acts as block protection. In the arrangement of Figure 2, the maximum possible axial distance between the stop element 14 and the locking ring 9 is given, wherein the spring 1 1 is maximally expanded. The axial distance between the stop element 14 and the locking ring 9 indicates a displacement path V of the locking ring 9. The, as sketched in Figure 2, maximum in the direction of the threaded spindle 4 displaced locking ring 9 is so spring loaded on the support surface 8 that even under long-lasting vibration loads does not lead to a rotation of the locking ring 9 relative to the modules 2, 3. For rotation of the locking ring 9, a ramp ring 16 is provided, which, as is apparent from Figure 3, engages the switching cam 10 of the locking ring 9. The ramp ring 16 not only causes a rotation of the locking ring 9, but also its displacement in the axial direction, wherein the locking ring 9 is displaced in the arrangement of Figure 3 to the stop in the direction of the stop element 14. In this case, the distance between the locking ring 9 and the sliding bearing element 7 corresponds to the maximum displacement path V. The locking ring 9 is rotatable in this positioning with a low driving torque to allow a transition of the linear actuator 1 in a new locking position.

LIST OF REFERENCE NUMBERS

1 linear actuator

2 first module

3 second module

4 threaded spindle

5 screw drive

6 support element

7 sliding bearing element

8 contact surface

9 locking ring

10 switching cams

1 1 spring

12 annulus

3 footbridge

14 stop element

15 cylindrical section

16 ramp ring

L longitudinal axis

V displacement path

Claims

claims

1 . Linear actuator (1), with two relative to each other linearly adjustable assemblies (2,3), as well as with respect to the assemblies (2,3) rotatable, on one of the modules (2) axially mounted locking ring (9) which cooperates with a Ramp ring (16) provided switching cam (10) and for receiving a between the assemblies (2,3) acting axial force is formed in at least one locking position, characterized by the locking ring (9) in the axial direction loading spring (1 1), by means of which the locking ring (9) against its axial bearing on one of the assemblies (2) is spring-loaded.

2. Linear actuator (1) according to claim 1, characterized in that the spring (1 1) is designed as a corrugated spring.

3. linear actuator (1) according to claim 1 or 2, characterized by acting as a block protection stop element (14), in its abutment on the locking ring (9) the spring (1 1) is maximally compressed.

4. Linear actuator (1) according to claim 3, characterized in that the stop element (1 1) describes a sleeve shape with a cylindrical portion (15) and an integrally formed on this, radially inwardly pointing web (13), wherein a spring ( 1 1) receiving annular space (12) adjacent to the inner wall of the cylindrical portion (15) and to an end face of the web (13).

5. linear actuator (1) according to one of claims 1 to 4, characterized by a on the end face of the locking ring (9) which faces away from the spring (1 1), arranged for contacting the locking ring (9) bearing surface (8) a sliding bearing element (7).

6. linear actuator (1) according to claim 5, characterized in that the locking ring (9) when pressed against the support surface (8) by the spring (1 1) is held in an unchanged angular position.

7. Linear actuator (1) according to one of claims 1 to 6, characterized in that a measured in the axial direction of maximum displacement (V) of the Locking ring (9) is not more than 10% of the measured in the same direction width of the locking ring (9).

8. linear actuator (1) according to one of claim 1 to 7, characterized in that the two assemblies (2,3) by means of a screw drive (5) are displaceable relative to each other.

9. linear actuator (1) according to claim 8, characterized in that the screw drive (5) is designed as a ball screw.

10. A device for height adjustment of a vehicle body, comprising a linear actuator (1) according to claim 1.