DE102022210565A1 - Linear actuator, movement mechanism with such a linear actuator, as well as excavator arm or telehandler with such a movement mechanism - Google Patents

Abstract

The present disclosure relates to a linear actuator (1). Furthermore, the present disclosure relates to a movement mechanism (BM) with such a linear actuator (1), as well as an excavator arm (BA) or telehandler with such a movement mechanism (BM). The linear actuator (1) has a screw drive (2) which has a threaded nut (3) and a threaded spindle (4) which is mounted on a housing (G) of the linear actuator (1) so as to be rotatable with respect to its longitudinal axis (l) by means of a rotary bearing (L1) and which is coupled or can be coupled to a motor (EM) for torque transmission, so that the threaded nut (3) can be moved linearly along the longitudinal axis (l) of the threaded spindle (4) by rotating the threaded spindle (4), and the housing (G) has, on the side facing away from the threaded nut (3), next to the rotary bearing (L1), a joint (GE), preferably designed as a ball joint (KG), the joint center (KGM) of which coincides with the longitudinal axis (l) of the threaded spindle. The connection of the linear actuator (1) to the movement mechanism (BM) is improved and can be made more flexible by the threaded nut (3) having two pivot pins arranged on opposite sides of the threaded nut (3). (3.S1, 3.S2), by means of which a common pin axis (3.Za) is formed, which intersects the longitudinal axis (l) substantially at a right angle.

Description

The present invention relates to a linear actuator, according to the preamble of claim 1, in particular a linear actuator with a screw drive, which has a threaded nut and a threaded spindle, which is rotatably mounted on a housing of the linear actuator with respect to its longitudinal axis by means of a rotary bearing and which is coupled or can be coupled to a motor for torque transmission, so that the threaded nut can move linearly along the longitudinal axis of the threaded spindle by rotating the threaded spindle, and the housing has, on the side facing away from the threaded nut, next to the rotary bearing, a joint, preferably designed as a ball joint, the center of the joint coinciding with the longitudinal axis of the threaded spindle.

Furthermore, the present disclosure relates to a movement mechanism according to patent claim 10, as well as an excavator arm according to patent claim 13 and a telehandler according to patent claim 14.

Background of the invention

In linear actuators of the type mentioned above, it is known that the threaded nut is connected to a boom tube. It is also known that the threaded spindle and the threaded nut are arranged in a housing of the respective electric linear actuator and the boom tube protrudes from the housing. The assembly consisting of the threaded nut and the boom tube can be moved linearly by means of the threaded spindle. The end of the boom tube protruding from the housing is known to be connected to a ball joint and a support element which has a receiving area for receiving a bolt passing through a joint head of the ball joint, so that the boom tube can be supported on the bolt with respect to a rotation about the longitudinal axis of the threaded spindle.

The linear actuator is coupled to the moving bodies that are to be moved relative to one another using the joint arranged on the housing and the ball joint arranged on the boom tube. The linear actuator is designed between these two joints and the distance between the two joints is therefore dependent on the total length of the linear actuator, in particular the length of the threaded spindle. This must be taken into account when designing the adjacent moving bodies.

State of the art

From the CN 108755794 B Various combinations of separately designed electric and hydraulic linear actuators are known for moving a movement mechanism, for example an excavator arm. Each electric or hydraulic cylinder has a separate housing. The electric linear actuators each have a screw drive with a threaded spindle and a threaded nut, which is connected to a boom tube. The threaded spindle and the threaded nut are arranged in a housing of the respective electric linear actuator and the boom tube protrudes from the housing. The assembly consisting of the threaded nut and the boom tube can move linearly by means of the threaded spindle. An electric motor for driving the threaded spindle is arranged outside the housing of the respective electric linear actuator and has a separate housing. The electric motor and threaded spindle are arranged next to one another so that their axes are parallel to one another.

Here too, the distance between the two opposing joints of each electric linear actuator depends on the total length of this linear actuator, in particular the length of its threaded spindle. Because the electric motor and threaded spindle are arranged next to each other, a gear between the electric motor and threaded spindle is inevitably necessary and the installation space of the linear actuator is relatively large, particularly in the radial direction of the threaded spindle, due to the electric motor arranged there.

Brief description of the invention

The present invention is based on the object of providing a linear actuator, a movement mechanism with such a linear actuator, as well as an excavator arm or a telehandler with such a movement mechanism, by means of which the problems of the prior art are reduced or eliminated. In particular, the connection of the linear actuator to the movement mechanism is to be improved and made more flexible.

This object is firstly achieved by a linear actuator according to claim 1.

Further advantageous embodiments are the subject of the subclaims.

More precisely, the task is solved by the threaded nut comprising two pivot pins arranged on opposite sides of the threaded nut, by means of which a common tenon axis which intersects the longitudinal axis substantially at a right angle.

This means that a moving body can be coupled directly to the threaded nut via the pivot pins. This makes it possible to achieve a particularly small distance between the bearing point formed by the pivot pins and the joint arranged on the housing when the threaded nut is in the fully retracted state. When the threaded nut is in the fully retracted state, the smallest possible distance is formed between the pivot pins and the joint, and when it is in the fully extended state, the largest possible distance is formed. This particularly small distance between the bearing point formed by the pivot pins and the joint arranged on the housing when the threaded nut is in the fully retracted state does not depend on the length of the threaded spindle. In particular, this distance is shorter than the length of the threaded spindle. A boom tube connected to the threaded nut, as described in the prior art, is not necessary for this design of the threaded nut with the two pivot pins. The pivot pins also serve to support the threaded nut against rotation around the longitudinal axis of the threaded spindle. This support is not provided by components of the linear actuator itself, but by a component coupled to the linear actuator.

Preferably, the housing is firmly connected to a support element or has such a support element. The support element can be brought into contact with a bolt passing through a joint head of the joint designed as a ball joint in such a way that the housing can be supported on the bolt with respect to a rotation about the longitudinal axis of the threaded spindle.

Such a ball joint can be used to avoid transverse or bending loads on the linear actuator or to compensate for elastic deformation due to the high forces. The support element then provides anti-twisting protection despite the ball joint, i.e. the housing does not rotate when the threaded spindle rotates due to the anti-twisting protection implemented by the support element, so that the function of the linear actuator, namely the axial movement of the threaded nut, is ensured.

The threaded nut preferably has a bellows, by means of which a sealing gap can be sealed, which is formed between the threaded nut and the threaded spindle on a front side of the threaded nut.

It is also preferred that a bellows is arranged on each of the two front sides of the threaded nut. Such bellows ensure that a lubricant does not get into the environment due to the centrifugal force created by the rotation of the threaded spindle, so that the contact surfaces on the screw drive, in particular between the threaded nut and the threaded spindle, are always sufficiently lubricated and no environmental influences, such as dirt and moisture, get into the lubricant and thus into the contact surfaces between the threaded spindle and the threaded nut.

In a further embodiment of the linear actuator, contact surfaces formed between the threaded nut and the threaded spindle are lubricated with grease.

Such a lubricant in the form of grease adheres particularly well to the contact surfaces, so that the risk of the lubricant flowing away from the contact surfaces is reduced. Such a grease is easily and safely prevented from escaping into the environment by the centrifugal force created by the rotation of the threaded spindle, particularly by means of the bellows mentioned above.

Advantageously, the threaded spindle is coupled via a rotationally fixed connection to a hollow shaft of the motor designed as an electric motor, the axis of rotation of which is arranged concentrically to the longitudinal axis of the threaded spindle.

The hollow shaft, the rotationally fixed connection and the threaded spindle preferably form a rigid, rotatable assembly, which can only be supported with two bearing points in the housing due to the rigid design

In a preferred embodiment of the linear actuator, coils or permanent magnets of the electric motor are arranged on an inner circumference of the housing.

The housing of the linear actuator also serves to house the electric motor, so that the linear actuator can be designed to be particularly compact. The coils or permanent magnets of the electric motor preferably act as the electric motor with coils and/or permanent magnets arranged on the outer circumference of the hollow shaft. Various designs of the electric motor are conceivable, e.g. the housing has coils and the hollow shaft has permanent magnets, so that a stepper motor is formed, for example.

Further preferred are a holding brake for the threaded spindle and the rotary bearing for position The threaded spindle is mounted on the housing of the linear actuator within the hollow shaft.

In this way, a particularly compact arrangement of the holding brake, the rotary bearing and the hollow shaft is achieved. In particular, these components can be arranged over a particularly short axial length. In particular, the axial length of the electromechanical linear actuator is thus minimized. One could also say that the length of the electric motor is then not included in the length of the linear actuator. The arrangement of the holding brake and the rotary bearing within the hollow shaft means that the holding brake and the rotary bearing are at least partially, preferably completely, facing an inner circumference of the hollow shaft with their outer circumference. One could also say that the holding brake and the rotary bearing are at least partially, preferably completely, arranged between two opposite end faces of the hollow shaft.

In a further preferred embodiment of the linear actuator, a damping element for damping axial shocks is arranged between the joint designed as a ball joint and the housing.

The linear actuator can thus be protected from axial impacts. The damping element is preferably designed as a mechanical damping element with at least one ring spring assembly, in which the impact energy is converted into heat by friction between rings lying on top of one another.

Further preferably, the support element leads past the damping element and has a sliding block which is mounted so as to be movable in the longitudinal direction for receiving the bolt which passes through the joint head of the ball joint.

The movement of the sliding block allows the housing to move in the axial direction relative to the bolt when the damping element is compressed due to axial forces. The support of the housing is maintained in every position of the housing relative to the bolt. This support is necessary to enable the relative movement between the threaded spindle and the housing. One could therefore also say that the use of the damping element is only made possible by the housing being movable relative to the bolt by means of the sliding block.

Furthermore, the object is achieved by a movement mechanism with a first and a second movement body, wherein the second movement body is pivotally or linearly mounted on the first movement body by means of a movement bearing, and a previously described linear actuator is provided, which is pivotally mounted on the first movement body by means of the joint at a distance from the movement bearing, and the second movement body has two fork arms spaced apart from one another, between which the threaded nut is arranged at a distance from the movement bearing such that the two pivot pins engage in a respective associated pivot bearing in the associated fork arm.

The particularly small distance between the bearing point formed by means of the pivot pin and the joint arranged on the housing when the threaded nut is in the maximum retracted state means that there is a particularly large scope for design in the structural implementation of the movement mechanism with the first and the second movement body.

In an advantageous embodiment of the movement mechanism, the joint is designed as a rotary joint.

Such a pure swivel joint provides anti-twisting protection, i.e. the housing does not rotate when the threaded spindle rotates due to the anti-twisting protection implemented by the swivel joint, so that the function of the linear actuator, namely the axial movement of the threaded nut, is ensured. An additional support element as anti-twisting protection is not required.

In a further, alternative embodiment of the movement mechanism, the joint is designed as a ball joint.

Such a ball joint makes it possible to avoid transverse or bending loads on the linear actuator, or to compensate for elastic deformation due to the high forces.

Furthermore, the task is solved by an excavator arm with a previously described movement mechanism.

In an excavator arm, the two moving bodies are arranged so that they can pivot relative to each other, so that the movement bearing is designed as a pivot bearing.

Furthermore, the task is solved by a telehandler with a previously described movement mechanism.

In a telehandler, the two moving bodies are arranged in a linearly movable manner relative to each other. net, so that the motion bearing is designed as a linear bearing.

Short description of the characters

• 1 zeigt schematisch einen Linearaktuator nach einer bevorzugten Ausführungsform der Erfindung in einer dreidimensionalen Ansicht.
• 2 zeigt eine schematische Schnittdarstellung des Linearaktuators nach 1.
• 3a zeigt eine schematische Darstellung eines Baggerarms mit einem den erfindungsgemäßen Linearaktuator beinhaltenden Bewegungsmechanismus.
• 3b zeigt schematisch in einer vergrößerten Detaildarstellung die Kopplung des zweiten Bewegungskörpers des Bewegungsmechanismus mit der Gewindemutter des erfindungsgemäßen Linearaktuators.

In the following, preferred embodiments are presented in more detail with reference to the accompanying figures.

• 1 shows schematically a linear actuator according to a preferred embodiment of the invention in a three-dimensional view.
• 2 shows a schematic sectional view of the linear actuator according to 1 .
• 3a shows a schematic representation of an excavator arm with a movement mechanism containing the linear actuator according to the invention.
• 3b shows schematically in an enlarged detailed view the coupling of the second moving body of the movement mechanism with the threaded nut of the linear actuator according to the invention.

Description of preferred embodiments

The linear actuator 1 has, among other things, a screw drive 2 which has a threaded nut 3 and a threaded spindle 4 which is mounted on a housing G of the linear actuator 1 so as to be rotatable with respect to its longitudinal axis I by means of a first rotary bearing L ₁ and which is coupled or can be coupled to a motor EM for torque transmission, so that the threaded nut 3 can move linearly along the longitudinal axis I of the threaded spindle 4 by rotating the threaded spindle 4. On the side facing away from the threaded nut 3, next to the rotary bearing L ₁ , the housing G has a joint GE, preferably designed as a ball joint KG, the joint center KG _M of which coincides with the longitudinal axis I of the threaded spindle.

The threaded spindle 4 has a spindle support 4.a at its end projecting from the housing G. It is conceivable, but not absolutely necessary, that the threaded spindle 4 is mounted on an adjacent moving body by means of the spindle support 4.a. The spindle support 4.a can also serve to prevent the threaded nut 3 from being moved beyond the end of the threaded spindle 4. In other words, a stop for the threaded nut 3 could be formed by means of the spindle support 4.a.

The threaded nut 3 comprises two pivot pins 3. _S1 , 3. _S2 arranged on opposite sides of the threaded nut 3, by means of which a common pin axis 3. _Za is formed, which intersects the longitudinal axis I substantially at a right angle.

By essentially, it is meant that the right angle can be deviated from by a few degrees, in particular by up to 10°. A moving body coupled to the linear actuator can be moved by means of the pivot pins 3. _S1 , 3. _S2 . The pivot pins 3. _S1 , 3. _S2 are mounted on the moving body in such a way that the threaded nut 3 is supported against rotation about the longitudinal axis l of the threaded spindle 4 by means of the pivot pins 3. _S1 , 3. _S2 in order to enable the linear movement of the threaded nut 3 relative to the threaded spindle 4.

The housing G is in accordance with 1 and 2 firmly connected to a support element AE or has such a support element AE. The support element AE can be brought into contact with a bolt BZ passing through a joint head KG _K of the joint GE designed as a ball joint KG in such a way that the housing G can be supported on the bolt BZ with respect to a rotation about the longitudinal axis l of the threaded spindle 4.

According to the 1 and 2 In the embodiment of the linear actuator 1 shown, the support element AE is designed as a flat plate, preferably of constant thickness, which is connected, in particular welded, with one of its end faces to an end face of the housing G.

The threaded nut 3 has a bellows _3.FB , by means of which a sealing gap can be sealed, which is formed between the threaded nut 3 and the threaded spindle 4 on one end face of the threaded nut 3.

According to 2 A bellows 3. _FB is arranged on each end face.

Contact surfaces forming between the threaded nut 3 and the threaded spindle 4 are lubricated with grease.

It would also be conceivable to use a cylindrical housing to seal the space between the threaded nut 3 and the threaded spindle 4, especially if oil is used as a lubricant.

The threaded spindle 4 is coupled via a rotationally fixed connection 5 to a hollow shaft EM.h of the motor designed as an electric motor EM, the axis of rotation of which is arranged concentrically to the longitudinal axis l of the threaded spindle 4.

The bearing of the rotating assembly consisting of threaded spindle 4, rotationally fixed connection Due to the rigid design, the connection between the bearing 5 and the hollow shaft EM.h can only be made with two bearings, namely the first pivot bearing L ₁ and a second pivot bearing L _2. The first pivot bearing L ₁ has in particular two tapered roller bearings or spherical roller bearings, preferably in an O-arrangement. The first pivot bearing L ₁ is in particular designed as a fixed bearing. The second pivot bearing L ₂ has a radial deep groove ball bearing. The second pivot bearing L ₂ is designed as a floating bearing, so that heat-induced relative movements are possible.

Coils EM.s or permanent magnets of the electric motor EM are arranged on an inner circumference of the housing G. The hollow shaft EM.h is preferably part of a rotor of the electric motor EM and thus has permanent magnets or coils on the outer circumference. A combination of coils EM.s arranged on the housing G and permanent magnets arranged on the hollow shaft EM.h is preferably provided.

A holding brake B for the threaded spindle 4 and the first rotary bearing L ₁ for supporting the threaded spindle 4 on the housing G of the linear actuator 1 are arranged within the hollow shaft EM.h.

The holding brake B is designed as a mechanical brake, for example. A part of the holding brake B assigned to the threaded spindle 4 and a part assigned to the housing G can be pressed against each other by means of a brake actuator. A rotary encoder 6 arranged on a front side of the threaded spindle 4 facing away from the boom tube 3a is arranged inside the hollow shaft EM.h. The rotary encoder 6 is preferably designed as an absolute rotary encoder. This makes it possible to determine the position of the threaded nut 3 without a position measuring system.

A damping element DM for damping axial shocks is designed according to 1 and 2 between the joint GE, which is designed as a ball joint KG, and the housing G.

The housing G of the damping element DM is designed in two parts so that the two parts are movable relative to each other in order to be able to change the axial length of the damping element DM in order to absorb the impact energies during the axial length change.

The support element AE passes the damping element DM and has a sliding block GL that is movably mounted in the longitudinal direction to accommodate the bolt BZ that passes through the joint head KG _K of the ball joint KG.

If the axial length of the damping element DM changes due to shock loads, the sliding block GL is moved linearly to the rest of the support element AE according to this length change.

The motor EM, which is preferably designed as an electric motor, is coupled to a control device ST for its control and/or regulation.

3a shows a movement mechanism BM as part of an excavator having an excavator arm BA with a first and a second movement body BK ₁ , BK ₂ . The second movement body BK ₂ is pivotally mounted on the first movement body BK ₁ by means of a movement bearing BL.

On the other hand, it would also be conceivable to mount the second moving body on the first moving body in a linearly movable manner by means of the motion bearing, especially if the motion mechanism is part of a telehandler.

The linear actuator 1 is pivotably mounted on the first moving body BK ₁ by means of the joint GE with a (first) distance a ₁ from the motion bearing BL. The second moving body BK ₂ has two spaced-apart fork arms GA ₁ , GA ₂ , between which the threaded nut 3 is arranged with a (second) distance a ₂ from the motion bearing BL such that the two pivot pins 3. _S1 , 3. _S2 engage in a respective associated pivot bearing GA _1SL , GA _2SL in the associated fork arm GA ₁ , GA ₂ . This coupling of the second moving body BK ₂ with the threaded nut 3 of the linear actuator 1 is particularly evident from the enlarged detailed illustration of 3b visible.

The particularly small distance between the pivot bearing GA _1SL , GA _2SL formed by means of the fork arms GA ₁ , GA ₂ for the pivot pins 3. _S1 , 3. _S2 and the joint GE arranged on the housing G in the maximum retracted state of the threaded nut 3 means that the second moving body BK ₂ can be pivoted over a particularly large range.

The GE joint is in accordance with 3a designed as a swivel joint, so that no associated support element is necessary. The joint GE, on the other hand, could also be designed as a ball joint KG.

List of reference symbols

1

Linear actuator

2

Screw drive

3

Threaded nut

3.S1

first pivot pin

3.S2

second pivot pin

3.Za

Pin axis

3.FB

Bellows

4

Threaded spindle

4.a

Spindle support

5

torsion-resistant connection

6

Rotary encoder

EM

Electric motor

EM.h

Hollow shaft

EM.s

Coils or permanent magnets of the electric motor EM

G

Housing

ST

Control device

DM

Damping element

ENG

joint

KG

Ball joint

KGM

Joint center

KGK

Joint head

AE

Support element

GL

Sliding stone

BZ

bolt

B

Holding brake

L1

first pivot bearing

L2

second pivot bearing

l

Longitudinal axis

BM

Movement mechanism

BK1

first moving body

BK2

second moving body

BL

Movement camp

GA1

first fork arm

GA2

second fork arm

GA1SL

Pivot bearing of the first fork arm GA ₁

GA2SL

Pivot bearing of the second fork arm GA ₂

BA

Excavator arm

a1

(first) distance

a2

(second) distance

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• CN 108755794 B [0005]

Claims (14)

Linear actuator (1) with a screw drive (2) which has a threaded nut (3) and a threaded spindle (4) which is mounted on a housing (G) of the linear actuator (1) so as to be rotatable with respect to its longitudinal axis (l) by means of a rotary bearing (L ₁ ) and which is coupled or can be coupled to a motor (EM) for torque transmission, so that the threaded nut (3) can be moved linearly along the longitudinal axis (l) of the threaded spindle (4) by rotating the threaded spindle (4), and the housing (G) has, on the side facing away from the threaded nut (3), next to the rotary bearing (L ₁ ), a joint (GE), preferably designed as a ball joint (KG), the joint center (KG _M ) of which coincides with the longitudinal axis (l) of the threaded spindle, characterized in that the threaded nut (3) comprises two pivot pins (3. _S1 , 3. _S2 ) arranged on opposite sides of the threaded nut (3), by means of which a common pin axis (3. _Za ) which intersects the longitudinal axis (l) substantially at a right angle. Linear actuator (1) according to Claim 1 , characterized in that the housing (G) is firmly connected to a support element (AE) or has such a support element (AE) which can be brought into contact with a bolt (BZ) passing through a joint head (KG _K ) of the joint (GE) designed as a ball joint (KG) in such a way that the housing (G) can be supported on the bolt (BZ) with respect to a rotation about the longitudinal axis (l) of the threaded spindle (4). Linear actuator (1) according to Claim 1 or 2 , characterized in that the threaded nut (3) has a bellows (3. _FB ) by means of which a sealing gap can be sealed which is formed between the threaded nut (3) and the threaded spindle (4) on an end face of the threaded nut (3). Linear actuator (1) according to Claim 3 , characterized in that contact surfaces forming between the threaded nut (3) and the threaded spindle (4) are lubricated with a grease. Linear actuator (1) according to one of the preceding claims, characterized in that the threaded spindle (4) is coupled via a rotationally fixed connection (5) to a hollow shaft (EM.h) of the motor designed as an electric motor (EM), the axis of rotation of which is arranged concentrically to the longitudinal axis (l) of the threaded spindle (4). Linear actuator (1) according to Claim 5 , characterized in that coils (EM.s) or permanent magnets of the electric motor (EM) are arranged on an inner circumference of the housing (G). Linear actuator (1) according to Claim 5 or 6 , characterized in that a holding brake (B) for the threaded spindle (4) and the rotary bearing (L ₁ ) for mounting the threaded spindle (4) on the housing (G) of the linear actuator (1) are arranged within the hollow shaft (EM.h). Linear actuator (1) according to one of the preceding claims, characterized in that a damping element (DM) for damping axial shocks is arranged between the joint (GE) designed as a ball joint (KG) and the housing (G). Linear actuator (1) according to Claim 8 , characterized in that the support element (AE) leads past the damping element (DM) and has a sliding block (GL) which is mounted so as to be movable in the longitudinal direction for receiving the bolt (BZ) which passes through the joint head (KG _K ) of the ball joint (KG). Movement mechanism (BM) with a first and a second movement body (BK ₁ , BK ₂ ), wherein the second movement body (BK ₂ ) is pivotally or linearly mounted on the first movement body (BK ₁ ) by means of a movement bearing (BL), and a linear actuator (1) according to one of the preceding claims is provided, which is pivotally mounted on the first movement body (BK ₁ ) by means of the joint (GE) at a distance (a ₁ ) from the movement bearing (BL), and the second movement body (BK ₂ ) has two fork arms (GA ₁ , GA ₂ ) spaced apart from one another, between which the threaded nut (3) is arranged at a distance (a ₂ ) from the movement bearing (BL) in such a way that the two pivot pins (3. _S1 , 3. _S2 ) in a respective associated pivot bearing (GA _1SL , GA _2SL ) in the associated fork arm (GA ₁ , GA ₂ ) intervene. Movement mechanism (BM) according to Claim 10 , characterized in that the joint (GE) is designed as a rotary joint. Movement mechanism (BM) according to Claim 10 , characterized in that the joint (GE) is designed as a ball joint (KG). Excavator arm (BA) with a movement mechanism (BM) according to one of the Claims 10 until 12 . Telehandler with a movement mechanism (BM) according to one of the Claims 10 until 12 .

Images