Adjustment device for a steering gear in a motor vehicle and motor vehicle steering gear

Abstract

The invention relates to an adjusting device 20 for a steering gear 1, particularly for motor vehicles, wherein an intermediate gear 27 is arranged in a gear train with at least three gears such that it can move along an adjusting line 105 to adjust the backlash in the gear train. The intermediate gear 27 can move along the adjusting line 105 such that the backlash in the entire gear train is automatically adjusted. The invention further relates to a motor vehicle steering gear 1 comprising the adjusting device 20.

Description

[0001] The invention relates to an adjustment device for a steering gear, in particular for motor vehicles, wherein an intermediate gear is arranged in a gear train with at least three gears such that it can move along an adjustment line in order to adjust tooth flank backlash in the gear train. Furthermore, the invention relates to a motor vehicle steering gear comprising the adjustment device.

[0002] Steering gears are generally used in motor vehicles to steer wheels. These steering gears connect a steering handle, such as a steering wheel, to a rack, which acts on the wheels via a tie rod end and thereby moves them. To increase the steering force, vehicles are equipped with actuators that amplify the driver's hand force, thus making it easier to physically steer the vehicle.

[0003] Various energy sources have proven practical for power steering; hydraulic, electric, and electromechanical systems are currently common. The electrification of the automotive powertrain has also led to the increasing use of electromechanical actuators for power steering.

[0004] The power steering can be installed at various locations within the steering gear. Common systems support the driver's steering forces directly in the steering column (column drive). Alternatively, the power steering can also be installed at the steering rack (rack drive). In rack-drive systems, it is common to install the power steering at a location other than the connection point to the steering column. This distributes the required installation space along the steering rack, allowing the entire system to be better integrated into the vehicle.

[0005] Steering assistance systems can also be designed as steer-by-wire (SbW) systems, in which there is no mechanical connection between the steering wheel and the steered vehicle wheels. The torque required to steer the vehicle wheels is provided by an actuator that adjusts the torque depending on the steering wheel angle. In particular, the adjustment device according to the invention is designed for use in an actuator for a SbW system.

[0006] In rack-drive systems, an electric motor generates torque, which is transmitted to a spindle nut via one or more gears. The spindle nut, in turn, transmits the torque to a spindle, where the rotation is converted into translation. In this context, it is often referred to as a rotation-translation gear.

[0007] However, due to the high motor speed of the power steering actuator, it is necessary to reduce the speed, as the required speed for the rotational-translational reduction gear is very low. A single-stage reduction has proven impractical, which is why multi-stage gears are increasingly being used.

[0008] Spur gears have become established as reduction gears, although these require a large amount of space. Reduction gears that use a belt to reduce the speed from the actuator to the spindle nut are also known. Due to the large distances between the actuator and the spindle nut, it is often necessary to use an intermediate gear in the reduction gear to minimize the required installation space.

[0009] Due to manufacturing and assembly tolerances, the backlash of spur gears can vary, which can adversely affect operational reliability. Adjusting the backlash in large-scale production is both costly and time-consuming.

[0010] Various systems are currently in use for adjusting the backlash. However, only one backlash of the gear train can be adjusted at a time, making the adjustment process time-consuming. CN107202157A discloses a device in which the backlash between the output gear of the transmission and the intermediate gear is adjusted using a rotation-translation adjuster, such as an eccentric. Subsequently, the backlash between the intermediate gear and the drive gear is adjusted using elongated holes, which allow the actuator to be moved relative to the intermediate gear.

[0011] Adjusting the backlash between the idler gear and the output gear involves an additional assembly step, which entails additional costs.

[0012] The object of the present invention is therefore to overcome the disadvantages of the prior art, in particular to provide an adjusting device for steering gears in which the adjustment of the tooth flank play of a gear drive is simplified.

[0013] This object is achieved by an adjustment device according to the invention for a steering gear in a motor vehicle, wherein a first section of a gear drive exists between a drive gear and an intermediate gear, and a second section of the gear drive exists between the intermediate gear and an output gear, wherein the intermediate gear is arranged to be movable along an adjustment line for adjusting a tooth flank backlash, wherein a tooth flank backlash of at least one section of the gear drive is adjustable.

[0014] The movable arrangement of the intermediate gear along the adjustment line makes it possible to adjust the tooth flank backlash in the entire gear train simply by adjusting the intermediate gear. This not only saves manufacturing costs but also enables subsequent adjustment, such as after maintenance. Furthermore, the tooth flank backlash can be automatically adjusted by the steering gear if the geometric dimensions of the gear train change due to wear during operation. Likewise, the adjustment device according to the invention makes it possible for the tooth flank backlash to adjust itself automatically in the event of irregular heating or cooling, as can occur in very hot or cold regions. All of these measures contribute to increasing the service life of the steering gear and maintaining proper function over a longer service life.

[0015] The intermediate gear is designed to be translationally movable along the adjustment line, meaning the gear's axis of rotation is not fixed relative to the steering gear housing. The intermediate gear's axis of rotation is the axis around which the gear rotates when the gears are meshing. It can also be designed so that the driven gear, which is located on the spindle nut, is not displaced via an eccentric or a slot.

[0016] The gear drive's backlash can be adjusted as follows. First, the motor flange with the drive pinion is moved relative to the steering gear housing using an eccentric or a slotted hole. This adjusts the backlash between the drive gear and the idler gear. However, since the idler gear is arranged so it can be moved along the adjustment line, moving the drive gear closer to the idler gear moves the idler gear toward the driven gear. This movement also simultaneously adjusts the backlash between the idler gear and the driven gear.

[0017] Using a feeler gauge, the backlash on at least one section of the gear train can be checked during assembly. The backlash on the other section of the gear train is automatically adjusted accordingly. Once the desired backlash has been achieved, the motor flange is secured to the housing.

[0018] According to a first embodiment, the adjustment line runs through the rotational axes of the drive gear and the driven gear. If either the drive gear or the driven gear has an eccentric locking device, the adjustment line can run through at least one of the rotational axes of the eccentric.

[0019] According to a preferred embodiment, the drive gear, the driven gear, and the intermediate gear are mounted relative to one another in such a way that adjusting the backlash on one of the sections of the gear drive causes a simultaneous adjustment of the backlash on one of the other sections of the gear drive. As already described in detail above, by adjusting the backlash on one of the sections of the gear drive, the backlash on the other section of the gear drive can also be adjusted by shifting the intermediate gear along the adjustment line. If, for example, the backlash on one of the sections of the gear drive is undersized, the intermediate gear shifts towards the other section of the gear drive. By shifting the intermediate gear, the backlash is automatically adjusted. The meshing gears generate a force on the intermediate gear, which acts along the adjustment line.This force moves the intermediate gear towards the other section of the gear train, creating a force equilibrium within the gear train and positioning the intermediate gear on the adjustment line.

[0020] According to one embodiment, one of the drive gear and the driven gear is mounted so that it can be displaced both rotationally and translationally. For example, the drive or driven gear can be adjusted via an eccentric. However, it is also possible to displace the drive or driven gear along a further straight line, for example, through an elongated recess such as a slot.

[0021] A further advantageous embodiment provides that the other of the output gear and the drive gear is fixedly mounted. It is provided that only the drive or output gear is arranged displaceably, and the other of the output or drive gears is fixedly mounted. This is sufficient in that a displacement of the intermediate gear and another gear is sufficient to adjust the tooth flank play between the two sections of the gear train. Due to the design of the steering gear, it is advantageous that the drive gear in particular is arranged displaceably and the output gear has a fixed bearing. A fixed bearing means that the axis of the gear cannot move relative to the steering gear housing. The other gear, on the other hand, can be arranged as a so-called floating bearing, which allows the gear to move along at least one direction of extent.

[0022] According to a further aspect of the invention, the steering gear comprises an assist device with at least one drive unit and a drive control system. The assist device can be designed, in particular, as an electric motor, wherein the electric motor can have a single or dual winding. Furthermore, the assist device can drive the drive gear hydraulically or pneumatically. In any case, the assist device must be designed such that it can drive a drive gear rotationally.

[0023] The drive control is designed to enable control of the drive unit of the support device. For this purpose, the drive control can comprise, in particular, hydraulic or pneumatic valves, electrical actuators, or electrical power electronics that enable control of the drive unit. The drive control can receive the signals required for control from a sensor, such as a steering angle sensor on the handle. In particular, it can be provided that the sensor on the handle specifies a target steering angle, to which the drive control regulates the drive unit so that a steering angle is achieved at the steered wheels of the motor vehicle.

[0024] According to a further embodiment, the drive unit is mounted so that it can be moved both rotationally and translationally. In conventional drive units such as an electric motor, the drive gear moves together with the drive unit when the latter is moved. It is therefore sufficient to move the drive unit relative to a steering gear housing so that the drive gear also moves. However, it is also possible to design only the drive gear so that it can be moved both rotationally and translationally, without moving the drive unit.

[0025] A further aspect of the invention provides that the intermediate gear is mounted in a recess that extends along the adjustment line. The recess can, in particular, be designed as an elongated hole. However, any other shape of recess that allows the intermediate gear to be displaced along the adjustment line is also possible.

[0026] According to a further embodiment, an adjustment direction of tooth flank play between the teeth of a steering gear for steering force assistance in a motor vehicle is provided, comprising a carrier, a drive gear which is connected to a drive, an output gear which drives a rotation-translation gear and an axis of rotation of the drive gear is arranged fixedly with respect to the carrier with respect to a steering gear housing, and an intermediate gear which connects the drive gear to the output gear, wherein the intermediate gear is arranged so as to be translationally displaceable along an adjustment line.

[0027] The carrier of a steering gear is designed to accommodate at least part of the bearing of the drive, intermediate, or driven gear. For this purpose, the carrier can have recesses into which rolling bearings are pressed, into which the rotational axes of the gears run. Furthermore, the carrier can have a cutout in which the intermediate gear can be moved along the adjustment line. The carrier also represents a connection between the drive unit, such as an electric motor, and the steering gear. In particular, a translational and rotational adjustment unit, such as an eccentric, can be provided for this purpose. However, it is also possible to insert a further element between the drive unit and the carrier, which carries out the rotational and translational movement of the drive unit. Furthermore, it is provided that the carrier, together with other components, represents the housing of the steering gear.

[0028] Further features, advantages and characteristics of the invention will be explained by the description of preferred embodiments of the invention with reference to the figures, which show: Fig. 1: a schematic diagram of the adjustment device; Fig. 2: a sectional view of a steering gear with an adjusting device according to the invention with a section through the drive, intermediate and driven gears; and Fig. 3: an example of a steering gear according to the invention with two drive units and an adjusting device according to the invention.

[0029] In Fig. Figure 1 shows a schematic diagram of the adjustment device 20. Here, a drive gear 23 meshes with an intermediate gear 27, which in turn meshes with an output gear 30. The rotational axis of the drive gear 101, the rotational axis of the intermediate gear 103, and the rotational axis of the output gear 104 are arranged along an adjustment line 105. The rotational axis of the intermediate gear 103 is mounted in the two opposite recesses 26, which extend along the adjustment line 105.

[0030] Either the drive or driven gear includes an eccentric 106, allowing the rotational axis of the adjusted gear to be shifted. In the schematic diagram shown, the drive gear 23 is adjustable using an eccentric 106. Due to the rotational and translational movement of the eccentric 106, the rotational axis of the drive gear 101 also shifts along a circular path 102. In this case, the adjustment line 105 can pass through any point on the rotational axis of the eccentric 102.

[0031] Fig. Figure 2 shows a sectional view of an adjustment device 20 according to the invention, with a section through the drive, intermediate, and driven gears. To generate an assist force, the steering gear 1 has a drive unit 2, which transmits the rotational force to a rotor shaft 21. The rotor shaft 21, in turn, is rotationally fixedly connected to the drive gear 23.

[0032] The engine torque transmitted to the drive gear 23 is transmitted via a first section of the gear train 25 to an intermediate gear 27. The intermediate gear 27 can move along a recess 26. It is provided that the recess 26 is as shown in Fig. 2 is shown along an imaginary line, here the sectional plane between the drive, intermediate, and driven gears. The intermediate gear 27 is in turn connected to an output gear 30 via a second section of the gear train 28. The adjusting device 20 surrounds a steering gear housing, which includes a carrier 24. The drive unit 2 is preferably attached to a housing part arranged opposite the carrier 24.

[0033] The output gear transmits the torque of the intermediate gear 27 to the spindle nut 31 of the rotation-translation gear 32. The torque applied by the drive unit 2 is transmitted by the gear drive to the spindle nut 31, in which a spindle 29 runs, which generates a translational movement for the tie rod end 5. The rotation-translation gear 32 can be designed in particular as a recirculating ball drive, wherein Fig. 2 the rolling elements of the gearbox are not shown.

[0034] As from Fig. As can be seen in Figure 2, the intermediate gear 27 can move freely along the recess 26. For example, if the backlash between the drive gear 23 and the intermediate gear 27 were to become too small, thus creating an undersized backlash, the intermediate gear 27 would move along the recess 26 toward the driven gear 30, as already described above. The direction of movement of the intermediate gear 27 would reverse accordingly if the backlash between the intermediate gear 27 and the driven gear 30 were to become too small.

[0035] Furthermore, it is provided that the recess 26 is formed in particular in the carrier 24, whereby a recess 26 can also be present only in a part of the carrier. As can be seen from Fig. As can be seen in Figure 2, the carrier 24 partially supports the bearings for the rotational axes of the gears of the gear train. A connection is also established between the drive unit 2 and the motor flange 22 to the carrier 24. The connection between the motor flange 22 and the carrier 24 can be made via a screw connection as shown. In particular, it is provided that the motor flange 22 is connected to the carrier 24 via an eccentric 106.

[0036] In Fig.3 shows a steering gear 1 having two drive units 2 with an associated drive control 3. However, in a variant not shown, only one drive unit 2 controlled by the drive control 3 may be provided. Both drive units 2 act via a gear drive on a spindle within the steering gear 1 (neither shown) and thereby generate a force on the tie rod end 5. The tie rod end 5 is attached to a wheel suspension of the steered wheels and generates a steering force at these.

[0037] The steering input is provided by connecting the steering handle from the driver to the steering gear 1 via a steering column connection 4 on the steering gear 1 or by means of a by-wire system into which the drive control 3 is integrated. In the first case, the steering column transmits the force applied by the driver to the steering gear 1, which is detected by a control unit and the drive control 3 is actuated accordingly. It can also be provided that one or more drive units 2 are provided for the steering gear 1. Particularly in heavy motor vehicles or commercial vehicles, several drive units and possibly several drive controls 3 are necessary to apply the steering force.

[0038] If necessary, isolated features can also be extracted from the combinations of features disclosed here and used in combination with other features to define the subject matter of the claim, dissolving any structural and / or functional relationship between the features. The order and / or number of steps of the methods can be varied. The methods can be combined with one another, for example, into a single method. List of reference symbols 1 steering gear 2 drive unit 3 Drive control 4 Steering column connection 5 Tie rod end 20 Adjustment device 21 Rotor shaft 22 Motor flange 23 Drive gear 24 carriers 25 First section of the gear drive 26 Recess 27 intermediate gear 28 Second section of the gear drive 29 spindle 30 Output gear 31 spindle nut 32 rotation-translation gears 101 Rotation axis drive gear 102 Rotary axis eccentric 103 Rotation axis intermediate gear 104 Rotation axis output gear 105 setting line 106 eccentric QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] CN 107202157A

[0010]

Claims

[1] Adjusting device (20) for a steering gear (1) in a motor vehicle, wherein a first section (25) of a gear drive exists between a drive gear (23) and an intermediate gear (27) and a second section (28) of the gear drive exists between the intermediate gear (27) and an output gear (30), characterized by in that the intermediate gear (27) is arranged to be movable along an adjustment line (105) for adjusting a tooth flank backlash, wherein a tooth flank backlash of at least one section (25, 28) of the gear drive is adjustable. [2] Adjusting device (20) for a steering gear (1) in a motor vehicle according to claim 1, characterized by that the adjustment line (105) runs through the axis of rotation of the output gear (104) and the drive gear (101). [3] Adjusting device (20) for a steering gear (1) in a motor vehicle according to claim 1 or 2, characterized bythat the drive gear (23), the driven gear (30) and the intermediate gear (27) are mounted relative to one another in such a way that an adjustment of the tooth flank play on one of the sections (25, 28) of the gear drive causes a simultaneous adjustment of the tooth flank play on the other of the sections (28, 25) of the gear drive. [4] Adjusting device (20) for a steering gear (1) in a motor vehicle according to one of the above claims, characterized by that one of the drive gear (23) and the output gear (30) is mounted so as to be rotatably and translatorily displaceable. [5] Adjusting device (20) for a steering gear (1) in a motor vehicle according to claim 4, characterized by that the other of the output gear (30) and the drive gear (23) is mounted in a stationary manner with respect to a steering gear housing. [6] Adjusting device (20) for a steering gear (1) in a motor vehicle according to one of the above claims, characterized bythat the intermediate gear (27) is slidably mounted along the adjustment line (105). [7] Adjusting device (20) for a steering gear (1) in a motor vehicle according to one of the above claims, characterized by that the intermediate gear (27) is mounted in a recess (26) which extends along the adjustment line (105). [8] Steering gear (1) for a motor vehicle with an adjusting device (20), in particular according to one of the above claims, characterized by that the steering gear (1) has a support device with at least one drive unit (2) and a drive control (3). [9] Steering gear (1) for a motor vehicle with an adjusting device (20) according to claim 8, characterized by that the drive unit (2) is mounted so as to be rotatably and translationally displaceable relative to the steering gear housing. [10] Steering gear (1) for a motor vehicle according to claim 8 or 9, comprising an adjusting device (20) according to claims 1 to 7. [11] Adjusting device (20) for adjusting tooth flank play between the gears of a steering gear (1) for steering power assistance in a motor vehicle, comprising - a carrier (24), - a drive gear (23) which is connected to a drive unit (2), - an output gear (30) which drives a rotation-translation gear (32) and an axis of rotation of the output gear (104) is arranged stationary with respect to the carrier (24), and - an intermediate gear (27) connecting the drive gear (23) to the driven gear (30), characterized by , that the intermediate gear (27) is arranged to be translationally displaceable along a setting line (105). [12] Adjustment device according to claim 11, characterized bythat a first section (25) of a gear drive exists between a drive gear (23) and an intermediate gear (27), and a second section (28) of the gear drive exists between the intermediate gear (27) and an output gear (30), wherein in particular the device is designed according to one of claims 2 to 9.

Images