CN105697573B

CN105697573B - Assembly with friction device

Info

Publication number: CN105697573B
Application number: CN201510881375.8A
Authority: CN
Inventors: 拉尔斯·舒曼; 拉斯洛·曼; 彼得·格雷布
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2014-12-15
Filing date: 2015-12-03
Publication date: 2022-03-29
Anticipated expiration: 2035-12-03
Also published as: DE102015220920A1; CN105697573A; DE102015220920B4

Abstract

The invention relates to an assembly having a friction device and having at least two components that can rotate relative to each other, in particular for actuating a clutch of a motor vehicle and at least forming part of a transmission and/or an actuator. According to the invention, between the components that can be rotated relative to one another, a ring spring element is provided, which influences the efficiency/friction during the relative rotation of the components and which has at least two active regions that are radially nested one inside the other and are connected to one another in one piece.

Description

Assembly with friction device

Technical Field

The invention relates to an assembly having a friction device and at least two components that can rotate relative to each other, in particular for actuating a clutch of a motor vehicle and which is at least a component of a transmission and/or an actuator.

Background

An actuator, for example for operating a clutch of a motor vehicle, is capable of converting a rotational movement of one member into an axial movement of another member. Here, the actuator itself can be any type of linear actuator, for example a PWG actuator (PWG, planetary rolling screw drive), a hydraulic slave cylinder, etc.

Planetary rolling-flight screw drives (PWGs) are usually formed by a screw, a screw nut and planetary rolling bodies arranged circumferentially between them and accommodated in a planetary carrier. The spindle, the spindle nut and the planetary rollers have a profile in order to transmit a rotational movement between the spindle and the spindle nut, wherein one of the components, the spindle or the spindle nut, is driven in rotation and the other component is moved in a rotationally fixed manner along the longitudinal axis of the spindle about an axial stroke corresponding to a set transmission ratio. In this case, the planetary rolling elements have two different profile sections which mesh with complementarily formed sections of the spindle or of the spindle nut. Thereby, a better efficiency is achieved than if the screw were directly accommodated on the screw nut.

DE 102010047800 a1 discloses an arrangement of a planetary rolling gear, in which an actuator part of a hydrostatic actuator, which is designed as a piston of a master cylinder, is coupled axially fixedly to a spindle which is arranged so as to be rotationally fixed and axially displaceable, wherein the axially fixed spindle nut is driven by an electric motor. Thus, as the screw nut rotates, the screw and screw nut move axially relative to each other. Since the cylinder housing which accommodates the piston and forms a pressure chamber with the piston is arranged fixedly and the spindle nut is supported axially on said cylinder housing, the piston builds up a pressure in connection with the rotational drive of the spindle nut, for example for operating motor vehicle components such as brakes, friction clutches, etc.

In such a spindle drive, which is optimized in terms of efficiency and is driven, for example, by means of an electric motor, is used in an actuator, for example a hydrostatic clutch actuator, and operates against a load, for example a clutch characteristic curve, it is problematic that, when a specific position needs to be held, a holding current and thus a holding torque are required in the electric motor, since the spindle drive (for example PWG) is not self-locking. The actuator therefore requires a permanent holding current or the position cannot be maintained in case of a power failure/malfunction (e.g. cable break, plug drop). Therefore, in the case of a clutch pressed by an actuator, there is a risk of the clutch closing undesirably.

Furthermore, annular springs are known, for example, for clutches. The ring spring is usually made of a metal wire which extends around the cylindrical component in a plurality of coils. Between the spring and the cylindrical member, a frictional force is caused when the cylindrical member rotates. The friction force can be influenced by stretching or releasing the ring spring.

The annular spring clutch is usually formed by a helical spring wound onto a shaft or a cylinder, which is fixed on one side to the drive. The slaving effect is based on the fact that the slaving torque is increased and added by friction by each coil. Thereby, the force causing the friction is simultaneously increased due to the wrap-around. Only a small friction occurs in the opposite direction, the spring slightly increasing its diameter, however without unwinding. The annular spring is also used in the slip clutch by virtue of its friction remaining during idle operation. As a free wheel element (freelaufefement), which has a self-reinforcing (locking) effect in one direction and a removal of the function in the other direction, wherein the spring only has to rotate against its basic friction.

A torsional vibration damper is known, for example, from DE 102007047394 a1, which has at least two parts which can be rotated relative to one another and which act against the action of a damping device with an energy accumulator acting in the circumferential direction, one of the parts being connectable to a drive and the other part being connectable to a shaft to be driven, wherein a torque limiter is additionally provided between the two parts in series with the damping device, which torque limiter acts at least in one of the possible relative rotational directions between the two parts and comprises at least one annular spring clutch which acts on a freewheel (freewheels) when a predetermined rotational angle between the two parts is reached and comprises at least one annular spring element. The solution is characterized in that at least one end of the annular spring element is connected in a rotationally fixed manner to an annular element which has a support region for the energy accumulator acting in the circumferential direction and/or a control region for the idling action. The annular element serves to absorb forces and is introduced into the annular spring element. The annular spring element is preferably arranged here in the axial direction between two annular elements. In the radial direction, at least one housing is arranged between the annular spring element and the energy store in order to additionally support the centrifugal force of the energy store acting in the circumferential direction.

In a further, yet undisclosed technical solution of the applicant, an assembly is proposed, in particular for operating a clutch of a vehicle, having a friction device with at least two components rotatable relative to each other, wherein a helical spring is provided between the components rotatable relative to each other, which helical spring influences the efficiency/friction when the components rotate relative to each other. The helical spring forms a ring spring at least in some regions, which can be a simple ring spring, a double ring spring or a ring torsion spring. The double annular spring described here has two active regions, which are arranged axially one behind the other. This requires a relatively large axial installation space.

Another technical solution of the applicant, which is not yet disclosed, likewise describes an assembly having a friction device with at least two components that can be rotated relative to one another, between which components a ring spring is arranged, which has two ring spring regions coupled to one another, wherein upon relative rotation of the components a low friction can be generated in one direction of rotation and a high friction can be generated in the other direction. The coupling of the two annular spring regions is effected here by a connecting element, which is designed as a sleeve or ring and positions the two radially nested annular spring regions relative to one another, such that a torque can be transmitted from the first annular spring region to the second annular spring region and vice versa. The two annular spring regions are realized here by two different annular springs. The solution is characterized by a smaller space requirement in the axial direction. In addition, in this embodiment, a large drag torque difference can be achieved by different cross sections/diameters of the inner and outer springs. There are, of course, the disadvantages here that the installation is made more difficult by the multi-part construction of the ring spring and the costs are increased by the use of a connecting element which connects the two ring spring regions.

Disclosure of Invention

The object of the invention is to provide an assembly, in particular for operating a clutch of a vehicle, having an input element, preferably a rotor, a screw or the like, which transmits torque and having an output element, which transmits torque or linear force, for example a screw or a screw nut or the like, wherein the input element and the output element are coupled to one another, and wherein the assembly is at least a component of a transmission and/or an actuator, wherein torque is transmitted from the input element to the output element via a torque path, by means of which assembly the friction and thus the efficiency between components which are rotatable relative to one another can be varied.

This object is achieved by an assembly according to the invention. Advantageous embodiments are provided below.

The assembly has, in parallel with the torque path, a friction device which generates additional friction between the input element and the output element, wherein the additional friction is generated depending on the direction of rotation of the input and/or output element.

Here, more friction is generated in one rotational direction and less friction is generated in the other rotational direction.

The relationship between the direction of rotation and the friction is advantageously selected such that, in the change of state of the component from the more energetically unfavorable state to the more energetically favorable state, a higher friction is produced than in the opposite case, so that a self-locking is thereby achieved in one state, for which maintenance otherwise energy must be expended.

Preferably, the rotational direction dependency of the friction device is expressed here such that it depends only on the relative rotational direction of the output element with respect to the input element or vice versa.

The input element can be a shaft, a screw or a rotor of an electric motor of the operating assembly, in particular a threaded screw or a similar component driven by the electric motor.

The output element can in turn be a screw, in particular a threaded screw, which is driven by a rotor as input element, or a corresponding shaft or a similar rotating member or but also a screw nut or a piston, which is set into rotary and/or linear motion by the screw.

In particular, it is proposed that the input element is coupled to the output element. The coupling can take place mechanically and/or magnetically.

If a torque path is referred to here, a path is essentially described through which the torque initially generated as torque passes in order to be operated, preferably by means of a linear movement of another component, for example a piston, a spindle nut supported with respect to the direction of rotation, or a slave cylinder.

Preferably, the friction device is arranged here parallel to the rotating component.

Preferably, the friction device is arranged in parallel with the screw, in particular the threaded screw, or in parallel with a rotor, which drives the screw, in particular the threaded screw.

In a preferred embodiment, the assembly has a friction device with at least two components that can be rotated relative to one another, in particular for actuating a clutch of a motor vehicle and at least forming part of a transmission and/or an actuator, between the components that can be rotated relative to one another there being arranged an annular spring element (Schlingfederelement) that influences the efficiency/friction when the components are rotated relative to one another, the annular spring element having at least two active regions that are nested radially one inside the other and are connected to one another in one piece. This also enables a large torque difference to be generated at a small working radius. This can be achieved with a small installation space requirement, in particular in the axial direction, and with a cost-effective and simple assembly due to the saving of components.

The radially inner active region of the annular spring element is in this case operatively connected by its inner diameter to the outer diameter of the first component in a rotationally fixed or friction-fit manner, and the radially outer active region of the annular spring element is operatively connected by its outer diameter to the inner diameter of the second component in a rotationally fixed or friction-fit manner.

Advantageously, the radially inner region of action and the radially outer region of action of the annular spring are connected to one another in one piece by a transition region.

It is also advantageous if the friction device is designed with exactly one element, i.e. with one annular spring element with two active regions. This involves a friction device without a sleeve, which is integrated with the first component in the outer region and with the second component, for example a screw, a threaded screw or a shaft, in the inner region.

A preferred embodiment provides that the annular spring element/active region is formed by a spring band/wire with a rectangular cross section. In this case, the spring band/wire of the radially outer active region is wound around the radially inner active region.

In a particularly advantageous embodiment, the spring band/wire is rotated/twisted by 90 ° in the transition region, whereby the cross section of the spring band/wire has a first orientation in the outer region of action and a rotational orientation relative thereto in the inner region of action.

Another advantageous embodiment provides that the inner active region of the annular spring element has an interference (Interferenz) or an excess/overlap with respect to the first component with a small active radius. Likewise, the outer active region of the annular spring element has an interference with respect to the second component having a large active radius. Preferably, the outer region of action has a greater interference with the second component than the inner region of action with the first component.

In a further advantageous embodiment, the inner active region of the annular spring element is formed with a greater number of coils than the outer active region.

When using an assembly with a friction device in an actuator, the actuator has a transmission that can be actuated by a drive and preferably converts a rotational movement into an axial movement, for example a PWG or other type of transmission, such that the friction associated with the rotational direction is increased slightly when the actuator is operated against a load or is increased significantly when the actuator is operated by means of an annular spring element between the first and second components, in order to stop a non-self-locking transmission, for example a PWG, in the event of a failure/failure of the drive, or in order to reduce or avoid a holding current (watchrom). When the friction device according to the invention is used in a PWG, the inner and outer regions of action are arranged between the rotating element of the PWG and a component of the actuator which is fixed to the housing or between two elements of the PWG which can rotate at different rotational speeds relative to one another.

For example, the annular spring element can be integrated between a spindle (first component) of the PWG, which is rotatably driven by the drive, and a spring pot (Federtopf) (second component) provided fixed to the frame/fixed to the housing, or within the housing of the PWG between two components that can be rotated relative to one another.

For example, the friction device, which is designed as a ring-shaped spring element, can also be arranged between the outer diameter of the ring gear, which meshes with the planetary gears of the PWG, and the inner diameter of the sleeve, which surrounds the PWG in the region of the ring gear.

By using a ring-shaped spring element with two active regions, an inner active region and an outer active region, it is possible to generate a low (as small as possible) friction in one direction of rotation and a large defined friction in the other direction. This prevents the load from pressing the actuating device back again (self-locking in one direction) when the engine is switched off.

In this case, radial force components in the same direction of the basic radial force can be superimposed by the two active regions of the annular spring element. Thus, two extreme states are obtained depending on the direction of rotation:

1. the radially inner active region with the smaller diameter is connected "fixedly" to the first component (shaft), and the outer active region generates a high friction with respect to the second component (hub), which achieves self-locking of the actuator.

2. The radially outer active region is "pressed" by its outer diameter outwards against the inner diameter of the second component (hub), whereby the inner active region reduces its pressure on the shaft and thus produces less friction.

Drawings

The invention is explained in detail below on the basis of exemplary embodiments and the associated drawings. The figures show:

fig. 1 shows a three-dimensional representation of a ring spring element according to the invention which is formed in one piece and has two active regions which are radially nested into one another,

figure 2 shows a front view of the ring spring element according to figure 1,

figure 3 shows a side view in longitudinal section of the ring spring element according to figure 1,

figure 4 shows a principle view of a ring spring element in mounted position,

figure 5 shows a longitudinal section through the free annular spring element according to figure 4,

fig. 6 shows a partial view of a ring spring element, which is rotated/twisted in cross section in the transition region between two active regions,

fig. 7 shows a longitudinal section through an actuator with a ring-shaped spring element according to the invention.

Detailed Description

Fig. 1 shows a three-dimensional representation of a ring spring element 1 according to the invention with two radially nested active regions 1.1, 1.2, wherein the active region 1.1 is arranged radially on the inside and the active region 1.2 is arranged radially on the outside. The transition region 1.3 connects the two active regions 1.1 and 1.2 to one another, so that a one-piece design of the annular spring element 1 is provided. The annular spring element 1 is preferably formed by a spring band or wire which is wound radially around the inner active region 1.1 in the form of an outer active region 1.2.

In the front view of the annular spring element 1 shown in fig. 2 and in the side view shown in fig. 3, the radial nesting of the two active regions 1.1, 1.2 is clearly visible, wherein the radially outer active region 1.2 has an outer diameter D2, via which the annular spring element 1 comes into contact with the inner diameter of a radially outer component, for example a hub or a ring gear/spring cup (not shown here). The radially inner region of action 1.1 has an inner diameter d1, which can be effectively connected to the outer diameter of a radially inner component, for example a shaft or a threaded spindle (not shown here). The two active regions 1.1, 1.2 are connected to one another in one piece by a transition region 1.3.

In the longitudinal section of the annular spring element 1 shown in fig. 3, it can also be seen that the cross section of the spring strips/wires is rectangular (square here). Spring strips/wires with a circular cross section have, for example, a higher surface pressure and thus cause higher wear relative to the components 2 and 3 (e.g. screw and spring pot). The rectangular cross section of the spring band has a height h and a width b, with h > b being preferred (see fig. 6).

Fig. 4 shows a schematic view of the annular spring element 1 in the mounted position between the component 2 designed as a shaft and the component 3 designed as a hollow shaft/hub. The shaft 2 and the hub 3 are arranged around a longitudinal/rotational axis a. The radially inner region of action 1.1 is assigned to the shaft 2 and the radially outer region of action 1.2 is assigned to the hub 3.

In fig. 5, the annular spring element 1 shown in longitudinal section is present directly before installation into the components, shaft 2 and hub 3, shown schematically in fig. 4. The inner active region 1.1 has an excess or interference a2 in relation to the shaft 2 with the small active radius, while the outer active region 1.2 has an interference a1 in relation to the hub 3 (large active radius). In the embodiment shown, the relationship a1 > a2 preferably exists. The interference a1, a2 is indicated by the proposed inner diameter D1 of the inner region of action 1.1 or by the proposed outer diameter D2 of the outer region of action 1.2.

Fig. 6 shows a partial view of a ring spring element 1 with an active region 1.2 arranged radially on the outside and with a transition region 1.3 connecting the two active regions 1.1, 1.2 in one piece, the active region 1.2 being wound around the radially inner active region 1.1. (to better illustrate the transition from the outer region of action 1.2 to the inner region of action 1.1, the two regions are not shown radially nested here). In this case, the annular spring element 1 is rotated/twisted in cross section in the transition region 1.3, so that the cross section of the spring band/wire has a first orientation in the outer active region 1.2 and a second orientation relative to this rotation in the inner active region 1.1. The spring strips of the outer active region 1.2 thus have a cross section h × b, while the spring strips of the inner active region 1.1 have a cross section h × b, where h ═ b and b ═ h. It is also advantageous for the inner region of action 1.1 to have a greater number of coils than the outer region of action 1.2, in order to ensure or increase the blocking effect of the region of action 1.1.

Fig. 7 shows a preferred embodiment of the annular spring element 1 according to the invention. In the longitudinal section, an efficiency-optimized screw drive in the form of a PWG is shown, the region of action 1.1 provided in the interior being in operative connection with a component 2 (threaded screw) of the screw drive. The outer active region 1.2 of the annular spring element 1 is operatively connected to a radially outer spring cup forming the component 3, which in turn is connected in a rotationally fixed manner to a bearing bracket 4 of the spindle bearing, which bracket is fixed to the housing or to the frame. The inner active region 1.1 surrounds the outer diameter of the spindle 2 by means of its inner diameter D1, while the outer diameter D2 of the outer active region 1.2 is surrounded by the inner diameter of the spring cup 3. The spindle 2, which is driven by a motor (not shown), is accommodated in a housing 5(PWG cartridge).

The assembly according to the invention with the friction device functions in the following manner:

in the case of a relative rotation (first direction of rotation) between the first component 2 (shaft/spindle) and the second component 3 (hub/hollow shaft/spring pot), the inner diameter d1 of the region of action 1.1 is reduced when the inner region of action 1.1 is closed toward the component 2, so that said inner diameter is connected in a rotationally fixed manner to the outer diameter of the component 2. By virtue of the output of the outer region of action 1.2, which is connected in one piece with the inner region of action 1.1 via the transition region 1.3, the latter opens out toward the component 3, whereby high friction and thus preferably self-locking occurs.

If, in the event of a reverse relative rotation (second direction of rotation) between component 2 (shaft/screw) and component 3 (hub/hollow shaft/spring pot), outer region of action 1.2 is closed off toward component 3, outer diameter D2 of outer region of action 1.2 increases, so that it presses rotationally fixed against the inner diameter of component 3. By virtue of the output of the inner active region 1.1, which is connected in one piece with the active region 1.2, the inner diameter d1 of the latter is increased so that it slides on the component 2. Only a small friction torque is generated.

With the solution according to the invention, an assembly is achieved with a friction device which also produces a large torque difference at a small effective radius. The two active regions 1.1, 1.2 of the annular spring element 1 thus form two spring sections having a larger outer diameter D2 (radially outer active region 1.2) for large braking torques and a smaller inner diameter D1 (radially inner active region 1.1) for small braking torques. In particular, there is a small installation space requirement in the axial direction, wherein the components are saved by the one-piece design of the annular spring element 1 with the two active regions 1.1, 1.2. The assembly according to the invention can therefore be realized cost-effectively and by means of simple mounting. The friction device with the annular spring element 1 assumes the holding function of the electric motor, wherein a drag torque is achieved, which is greater than the holding torque. Depending on the direction of the relative movement, the friction between the components increases only slightly when the actuator is operated against a load and significantly (with a targeted value) when the load is operated, in order to thus stop the efficiency-optimized, non-self-locking screw drive, for example, in the event of a fault (for example, in the event of a power failure).

List of reference numerals:

1 annular spring element

1.1 regions of action arranged radially inwardly

1.2 regions of action arranged radially outside

1.3 transition region

2 component/shaft/screw

3 component/hub/hollow shaft/spring can

4 bearing bracket

5 casing/PWG Sleeve

Longitudinal axis A

Inner diameter of the region of action inside d1

Outer diameter of the region of action outside D2

b width of the spring band/wire of the active region outside

h height of the spring band/wire of the active region outside

b width of the spring band/wire of the inner active area

h height of spring band/wire of inner active area

Claims

1. An assembly having an input element for transmitting torque and having an output element for transmitting torque or linear force, wherein the input element and the output element are mechanically and/or magnetically coupled to one another, and wherein the assembly is at least a component of a transmission and/or an actuator, wherein torque is transmitted from the input element to the output element via a torque path,

characterized in that a friction device is provided parallel to the torque path, which friction device generates additional friction between the input element and the output element, wherein the additional friction is generated depending on the direction of rotation of the input element and/or the output element.

2. An assembly according to claim 1, characterized in that the friction means comprise at least two components (2, 3) which can be rotated relative to each other, between which components (2, 3) an annular spring element (1) is arranged which influences the efficiency/friction when the components (2, 3) are rotated relative to each other, which annular spring element has at least two active regions (1.1, 1.2) which are nested radially within each other and are connected to each other in one piece.

3. The arrangement as claimed in claim 2, characterized in that the radially inner active region (1.1) of the annular spring element (1) is operatively connected by means of its inner diameter (D1) to the outer diameter of the first component (2) in a rotationally fixed or friction-fitted manner, and the radially outer active region (1.2) of the annular spring element (1) is operatively connected by means of its outer diameter (D2) to the inner diameter of the second component (3) in a rotationally fixed or friction-fitted manner.

4. The assembly according to claim 2 or 3, characterized in that the radially inner region of action (1.1) and the radially outer region of action (1.2) are connected to one another in one piece by a transition region (1.3).

5. An assembly according to claim 2 or 3, characterized in that the annular spring element (1)/the active region (1.1, 1.2) consists of a spring band/wire with a rectangular cross section.

6. Assembly according to claim 5, characterized in that the spring band/wire is turned/twisted by 90 ° in the transition region (1.3), whereby the cross section of the spring band/wire has a first orientation in the outer region of action (1.2) and a rotational orientation relative thereto in the inner region of action (1.1).

7. An assembly according to claim 2 or 3, characterized in that the radially outer region of action (1.2) is wound around the radially inner region of action (1.1).

8. The assembly according to claim 2, characterized in that the inner active region (1.1) of the annular spring element (1) has an interference (a2) with respect to the first component (2) having a small active radius.

9. The assembly according to claim 2, characterized in that the outer active region (1.2) of the annular spring element (1) has an interference (a1) with respect to the second component (3) having a large active radius.

10. The assembly according to claim 8 or 9, characterized in that the interference (a1) of the outer region of action (1.2) with respect to the second component (3) is greater than the interference (a2) of the inner region of action (1.1) with respect to the first component (2).

11. An assembly according to claim 2 or 3, characterized in that the inner active region (1.1) of the annular spring element (1) has a greater number of coils than the outer active region (1.2).

12. An assembly according to claim 2 or 3, characterized in that the assembly is used for operating a clutch of a vehicle.

13. An assembly according to claim 2 or 3, wherein the input element is a rotor or a screw and the output element is a screw or a screw nut.