Actuator with planetary roller screw spindle

Abstract

Actuator (1) with planetary roller screw (PWG) (5), in particular for actuating a clutch of a vehicle, wherein several planetary rollers engage with a screw (6) which mesh with a ring gear surrounding the planetary rollers, wherein the planetary rollers are positioned at both ends in a planetary roller carrier, and the planetary roller carriers are supported in a sleeve surrounding the ring gear and enclosed by a PWG housing (4), and with a sensor system comprising at least one sensor element (7) for determining the axial position of the axially movable component of the actuator (1), characterized in that - that in an actuator (1) with an axially movable spindle (6) the sensor element (7) is arranged at the end region of the spindle (6) in a groove of the spindle (6), - the spindle (6) runs in an axial direction through a circuit board (2) containing the sensor technology, - the sensor system includes a sensor module (8) that detects the position of the sensor element (7) and is directly contacted on the circuit board (2) and - the sensor module (8) is located on the side of the circuit board (2) that points away from the piston.

Description

[0001] The invention relates to an actuator with a planetary roller screw (PWG) according to the preamble of the first claim.

[0002] Planetary roller screws (also referred to as planetary roller screw drives) have been state of the art for many years and are described, for example, in DD 0277308 A5. From publication DE 10 2010 047 800 A1, for example, a planetary roller screw drive is known which is included in a hydrostatic actuator in the form of a hydrostatic clutch actuator to convert a rotary motion generated by an electric motor into an axial motion. A planetary roller screw drive, comprising a threaded spindle, a nut arranged on the threaded spindle, and several planets distributed around the circumference and arranged between the threaded spindle and the nut, which are arranged to roll on the inner circumference of the nut and on the outer circumference of the threaded spindle, is known from publication DE 10 2010 011 820 A1.This solution incorporates a preloading device for the planetary gears, wherein the nut has two axially movable nut parts, and wherein the preloading device includes a spring element spring-loaded against one of the nut parts. The nut performs two functions: firstly, it is a transmission component, and secondly, it is part of the preloading device.

[0003] It is also known (see DE 10 2011 088 995 A1) to perform an absolute measurement for slip detection of a PWG with a spindle nut arranged on a threaded spindle and with a plurality of planets arranged around the circumference, which are in rolling engagement with the threaded spindle and the spindle nut, wherein a sensor element arranged axially immovable relative to the spindle nut detects an axial displacement of the threaded spindle and the spindle nut relative to each other, wherein the spindle nut is rotatably mounted on a housing having the sensor element about the spindle axis.

[0004] Other relevant actuator systems are known from DE 10 2007 007 234 A1, US 5 086 861 A and DE 10 2012 207 237 A1.

[0005] It is also known to use an actuator for release systems of vehicle clutches in which a piston axially displaceable in a housing is actuated by means of a drive via a PWG.

[0006] If absolute position information is required for the use of a corresponding linear actuator, separately mounted absolute position sensors are used for this purpose; alternatively, when using pitch-preserving gearboxes (KGT, SPWG, motion thread), the incremental angle information of the rotor position sensor can be used with additional referencing / plausibility checks to calculate the absolute position information.

[0007] However, both a separately mounted absolute position sensor and the components for referencing / plausibility checks require additional installation space, increase the system weight, and thus the overall cost of the actuator. The connection of the separate position sensor is often sensitive to vibrations and tolerances. Furthermore, the referencing / plausibility check process takes time and requires movement of the actuator, which is not permissible in every application.

[0008] The known systems require a large axial and radial installation space overall and are relatively complex.

[0009] The object of the present invention is to develop an actuator with a planetary roller screw drive that requires a small installation space and enables a compact arrangement of an absolute displacement sensor within the actuator.

[0010] This problem is solved by the characterizing features of the first patent claim.

[0011] Advantageous embodiments result from the dependent claims.

[0012] The actuator has a planetary roller thread spindle (PWG) and is used in particular for actuating a clutch of a vehicle, wherein several planetary rollers engage with a spindle, which mesh with a ring gear surrounding the planetary rollers, wherein the planetary rollers are positioned at both ends in a planetary roller carrier, and the planetary roller carriers are supported in a sleeve surrounding the ring gear and enclosed by a PWG housing, as well as with a sensor system comprising at least one sensor element for determining the axial position of the axially movable component of the actuator, wherein, according to the invention, in an actuator with an axially movable spindle, the sensor element is arranged at the end region of the spindle in a groove of the spindle, or in an actuator with an axially movable gearbox housing, the sensor element is arranged on the gearbox housing.

[0013] This direct arrangement is advantageously very rigid and not very sensitive to vibration, since no additional components need to be placed between the sensor element and the spindle or between the sensor element and the gearbox housing. The component containing the sensor element is preferably rotationally fixed, so that any change in the position of the sensor element is necessarily due to an axial displacement of the sensor element.

[0014] According to the invention, the spindle runs in an axial direction through a circuit board containing the sensor technology.

[0015] The sensor element is preferably located in close proximity to the circuit board.

[0016] In particular, the sensor is designed in the form of a Hall sensor / magnetic field sensor and the sensor element is a magnet.

[0017] To detect the position of the sensor element, the sensor system according to the invention includes a sensor module that is directly contacted on the circuit board and is located on the side of the circuit board facing away from the piston. In actuators where the spindle runs through the circuit board and is therefore always in close proximity to it, this arrangement is particularly advantageous, as direct contact without cables or similar components is possible. Alternatively, in an unclaimed embodiment, the sensor module can be arranged spatially separated from the circuit board. In this case, corresponding leads are provided from the sensor module to the circuit board.

[0018] The sensor component can be, for example, a Linear Voltage Differential Transformer (LVDT).

[0019] Furthermore, the sensor module is preferably arranged radially close to the sensor element.

[0020] The actuator according to the invention advantageously requires a small installation space and has a compact arrangement of the absolute displacement sensor within the actuator.

[0021] The invention is explained in more detail below with reference to an exemplary embodiment and an associated drawing, without being limited to these.

[0022] It shows: Fig. 1. The schematic representation of an actuator according to the invention.

[0023] In Fig. Figure 1 shows a schematic representation of an actuator 1 according to the invention, which has a planetary roller screw (PWG) 5, with which the rotary motion of a rotor generated by an electric motor 3 is converted into an axial stroke motion H of the spindle 6 of the PWG 5. The PWG 5 and part of the spindle 6 are enclosed by a PWG housing 4. The PWG housing 4 is rotationally fixed to a motor block that accommodates the drive / electric motor 3.

[0024] The spindle 6 is supported against rotation, for example by a guide nut, and extends axially through a circuit board 2 containing the sensor. The circuit board has a through-hole, i.e., a bore for receiving the spindle 6. A sensor element 7, here a position magnet 7, is arranged in a groove on the spindle 6, in the embodiment shown here at the axial end of the spindle which points away from the piston.

[0025] A sensor module 8 is contacted directly on the circuit board 2 in radial proximity to the sensor element 7 for detecting its position. It is essential that the sensor element 7 is axially adjustable to such an extent that it remains within the detection range of the sensor module 8 in both of its axial extreme positions.

[0026] During an axial stroke movement H of the spindle 6, the sensor element 7 is displaced in the axial direction. The displacement of the sensor element 7 is detected by the sensor module 8. In this way, conclusions can be drawn about the axial position of the spindle 6 and thus of the other axially movable components (second sleeve / piston) connected to it.

Claims

[1] Actuator (1) with planetary roller screw (PWG) (5), in particular for actuating a clutch of a vehicle, wherein several planetary rollers engage with a screw (6) which mesh with a ring gear surrounding the planetary rollers, wherein the planetary rollers are positioned at both ends in a planetary roller carrier, and the planetary roller carriers are supported in a sleeve surrounding the ring gear and enclosed by a PWG housing (4), and with a sensor system comprising at least one sensor element (7) for determining the axial position of the axially movable component of the actuator (1), characterized by , - that in an actuator (1) with an axially movable spindle (6) the sensor element (7) is arranged at the end region of the spindle (6) in a groove of the spindle (6), - the spindle (6) runs in an axial direction through a circuit board (2) containing the sensor technology, - the sensor system includes a sensor module (8) that detects the position of the sensor element (7) and is directly contacted on the circuit board (2) and - the sensor module (8) is located on the side of the circuit board (2) that points away from the piston. [2] Actuator (1) according to claim 1, characterized by , that the sensor element (7) is located in close proximity to the circuit board (2). [3] Actuator (1) according to one of claims 1 or 2, characterized by , that the sensor is designed in the form of a Hall sensor / magnetic field sensor and that the sensor element (7) is a magnet.. [4] Actuator (1) according to any one of claims 1 to 3, characterized by , that the sensor module (8) is arranged radially close to the sensor element (7).

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