Steering actuator

Abstract

The utility model relates to vehicle technical field especially relates to a steering execution device. Wherein, two drive parts and two worm one to one setting, drive part installs in the casing, worm rotation is connected in the casing, drive part is connected with the transmission of worm, and drive part can drive worm rotation, worm wheel rotation is connected in the casing, two worms are arranged respectively in both sides of worm wheel, two worms all are engaged with the same group of tooth of worm wheel, pinion shaft is coaxial fixed in worm wheel, the outer wall of pinion shaft is provided with drive tooth, drive tooth is engaged with rack, rack sliding connection is in the casing, and rack is connected in the wheel through pull rod, drive tooth can drive rack to remove to push wheel rotation. The steering execution device dispenses with a pair of pinion shaft and rack interlock and the use of relevant components, reduces the volume, reduces the cost, improves the synchronism of two execution mechanisms, and further improves the steering precision, reduces the system friction, improves the safety redundancy of steering execution mechanism.

Description

Technical Field

[0001] This utility model relates to the field of vehicle technology, and in particular to a steering actuator. Background Technology

[0002] Steer-by-wire mainly consists of a hand-feed simulator located in the cockpit and a steering actuator located on the chassis. The hand-feed simulator mainly provides feedback on the driver's hand force, while the steering actuator mainly realizes the displacement of the wheels, thereby achieving steering.

[0003] In existing technologies, steering actuators typically consist of a dual-worm gear / dual-worm wheel structure or a dual-belt structure. The dual-worm gear / dual-worm wheel structure uses two separate drive mechanisms to drive the two ends of the steering shaft, resulting in a large size, inconvenient installation, complex structure, and high cost. The two independent drive mechanisms also suffer from poor synchronization; the two independent angular position signals are prone to deviation, affecting the actuator's precise drive of the steering gear; and the meshing friction between the two pinion shafts and racks is significant. The dual-belt structure is also large, inconvenient to install, and particularly expensive; the belt carries the risk of tooth skipping; and the system's power assist mechanism has low stiffness, hindering system tuning. All of these factors ultimately affect the system's steering accuracy.

[0004] Therefore, there is an urgent need for a steering actuator to solve the above-mentioned technical problems. Utility Model Content

[0005] The purpose of this invention is to propose a steering actuator that can reduce size, lower cost, reduce friction, improve steering accuracy, and increase safety redundancy.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] A steering actuator, comprising:

[0008] case;

[0009] A drive assembly includes a worm gear, two drive components, and two worms. The two drive components are arranged in a one-to-one correspondence with the two worms. The drive components are mounted on the housing, and the worms are rotatably connected to the housing. The drive components are drively connected to the worms and can drive the worms to rotate. The worm gear is rotatably connected to the housing. The two worms are respectively arranged on both sides of the worm gear, and both worms mesh with the same set of teeth of the worm gear.

[0010] A steering assembly, comprising a pinion shaft and a rack, wherein the pinion shaft is coaxially fixed to the worm gear, and the outer wall of the pinion shaft is provided with driving teeth that mesh with the rack. The rack is slidably connected to the housing, and the rack is connected to the wheel via a tie rod. The driving teeth are capable of driving the rack to move, thereby driving the wheel to rotate.

[0011] As a preferred embodiment of the aforementioned steering actuator, the drive assembly further includes two first bearings, which are arranged in a one-to-one correspondence with the two worm gears. The outer ring of the first bearing is fixed to the housing, and the inner ring of the first bearing is fixed to the worm gear.

[0012] As a preferred embodiment of the aforementioned steering actuator, the drive assembly further includes two couplings, each corresponding to one of the two drive components, and the couplings are disposed between the drive component and the worm gear.

[0013] As a preferred embodiment of the aforementioned steering actuator, the drive assembly further includes two first clearance adjustment mechanisms, each corresponding to one of the two worm gears. The first clearance adjustment mechanism is located at the end of the worm gear furthest from the coupling. Each first clearance adjustment mechanism includes a second bearing, a protective sleeve, a first elastic element, and an adjusting element. The protective sleeve is disposed within the housing. The inner ring of the second bearing is fixed to the worm gear, and the outer ring of the second bearing is fixed to the protective sleeve. The adjusting element is slidably disposed within the housing. The first elastic element is disposed between the adjusting element and the protective sleeve, and is configured to always have a tendency to push the protective sleeve toward the worm gear.

[0014] As a preferred embodiment of the aforementioned steering actuator, the steering assembly further includes a third bearing and a fourth bearing, which are respectively disposed at both ends of the pinion shaft, with the third bearing close to the worm gear. The outer rings of the third bearing and the fourth bearing are both fixed to the housing, and the inner rings of the third bearing and the fourth bearing are both fixed to the pinion shaft.

[0015] As a preferred embodiment of the aforementioned steering actuator, the steering assembly further includes a gear, which is sleeved on the pinion shaft and has the drive teeth.

[0016] As a preferred embodiment of the aforementioned steering actuator, the steering assembly further includes a second clearance adjustment mechanism. The second clearance adjustment mechanism includes a fifth bearing, a second elastic element, and an adjusting plug. The fifth bearing is slidably disposed on the housing, and one end of the fifth bearing abuts against the end of the rack away from the pinion shaft. The adjusting plug is slidably disposed on the housing. The second elastic element is disposed between the adjusting plug and the other end of the fifth bearing, and the second elastic element is configured to always have a tendency to push the fifth bearing toward the pinion shaft.

[0017] As a preferred embodiment of the aforementioned steering actuator, the second clearance adjustment mechanism further includes a buffer pad, which is disposed between the fifth bearing and the adjusting plug.

[0018] As a preferred embodiment of the aforementioned steering actuator, the steering actuator further includes an angle sensor connected to the worm gear, and the angle sensor is used to detect the rotation angle of the worm gear.

[0019] As a preferred embodiment of the aforementioned steering actuator, the steering actuator further includes a position sensor disposed on the drive member, the position sensor being communicatively connected to the drive member, and the position sensor being used to detect the rotation angle of the drive member and thereby calculate the position of the rack.

[0020] The beneficial effects of this utility model are:

[0021] This utility model relates to a steering actuator. The steering actuator includes: a housing, a drive assembly, and a steering assembly. The drive assembly includes a worm gear, two drive members, and two worms. The two drive members are arranged one-to-one with the two worms. The drive members are mounted on the housing, and the worms are rotatably connected to the housing. The drive members are drively connected to the worms and can drive the worms to rotate. The worm gear is rotatably connected to the housing. The two worms are respectively arranged on both sides of the worm gear, and both worms mesh with the worm gear. The steering assembly includes a pinion shaft and a rack. The pinion shaft is coaxially fixed to the worm gear. The outer wall of the pinion shaft is provided with drive teeth that mesh with the rack. The rack is slidably connected to the housing and connected to the wheel through a tie rod. The drive teeth can drive the rack to move, thereby driving the wheel to rotate. Compared to existing technologies, this steering actuator provides sufficient steering force by driving a worm gear with two worms, eliminating the need for another worm gear, thus reducing size and cost. It also eliminates the need for a pair of pinion racks and related meshing components, reducing price increases and lowering costs. Furthermore, by eliminating the meshing of a set of pinion shafts and racks, the synchronization of the two actuators is improved through the engagement of a single pair of pinion shafts with the rack, thereby enhancing steering accuracy. The elimination of a set of pinion shafts and racks also reduces system friction, improving steering feel. The presence of two drive components increases the safety redundancy of the steering actuator. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of this utility model and these drawings without creative effort.

[0023] Figure 1 This is a first structural schematic diagram of the steering actuator provided in this embodiment of the utility model;

[0024] Figure 2 This is a second structural schematic diagram of the steering actuator provided in this embodiment of the utility model;

[0025] Figure 3 This is a schematic diagram of the third structure of the steering actuator provided in this embodiment of the utility model;

[0026] Figure 4 This is a structural cross-sectional view of the steering actuator provided in an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the structure of the first gap adjustment mechanism provided in this embodiment of the utility model;

[0028] Figure 6 This is a schematic diagram of the structure of the second gap adjustment mechanism provided in an embodiment of the present invention.

[0029] In the picture:

[0030] 1. Shell;

[0031] 2. Drive assembly; 21. Worm gear; 22. Drive component; 23. Worm; 24. First bearing; 25. Coupling; 26. Second bearing; 27. Protective sleeve; 28. First elastic element; 29. ​​Adjusting element;

[0032] 3. Steering assembly; 31. Pinion shaft; 32. Rack; 33. Third bearing; 34. Fourth bearing; 35. Gear; 36. Fifth bearing; 361. Mounting groove; 37. Second elastic element; 38. Adjusting plug; 39. Buffer pad; 301. Bearing housing; 302. Pressure ring; 303. Buffer ring; 304. Sealing ring. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0034] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0037] like Figures 1 to 6 As shown, this utility model relates to a steering actuator. The steering actuator includes: a housing 1, a drive assembly 2, and a steering assembly 3. The drive assembly 2 includes a worm gear 21, two drive members 22, and two worms 23.

[0038] Specifically, two driving components 22 are correspondingly arranged with two worm gears 23. The driving components 22 are installed on the housing 1, and the worm gears 23 are rotatably connected to the housing 1. The driving components 22 and worm gears 23 are connected in a transmission manner, and the driving components 22 can drive the worm gears 23 to rotate. The worm wheel 21 is rotatably connected to the housing 1. The two worm gears 23 are respectively arranged on both sides of the worm wheel 21, and both worm gears 23 mesh with the worm wheel 21. The steering assembly 3 includes a pinion shaft 31 and a rack 32. The pinion shaft 31 is coaxially fixed to the worm wheel 21. The outer wall of the pinion shaft 31 is provided with driving teeth, which mesh with the rack 32. The rack 32 is slidably connected to the housing 1 and connected to the wheel. The driving teeth can drive the rack 32 to move, thereby driving the wheel to rotate. Compared to existing technologies, this steering actuator, driven by two worm gears 23 and a single worm wheel 21, can still provide sufficient steering force. It eliminates the need for a pair of pinion shafts 31 and rack 32 meshing and related components, reducing size and cost. Furthermore, by eliminating the meshing of a set of pinion shafts 31 and rack 32, and using only a single pair of pinion shafts 31 to drive the gears to engage with the rack 32, the synchronization of the two actuators is improved, thus enhancing steering accuracy. The elimination of a set of pinion shafts 31 and rack 32 also reduces system friction, optimizing steering feel. The presence of two drive components 22 increases product safety redundancy. Further, the drive component 22 is a motor.

[0039] Optionally, the drive assembly 2 also includes two first bearings 24, which are arranged one-to-one with two worm gears 23. The outer ring of the first bearing 24 is fixed to the housing 1, and the inner ring of the first bearing 24 is fixed to the worm gear 23, which can reduce the friction of the worm gear 23 and ensure the output torque of the worm wheel 21.

[0040] Optionally, the drive assembly 2 also includes two couplings 25, which are arranged one-to-one with the two drive components 22. The couplings 25 are located between the drive component 22 and the worm gear 23, and can enable the output shaft of the drive component 22 and the worm gear 23 to rotate synchronously during the transmission of motion and torque. At the same time, they can compensate for the relative displacement between the shafts, buffer and reduce vibration, and provide protection in case of overload.

[0041] Optionally, the drive assembly 2 also includes two first clearance adjustment mechanisms, which are arranged one-to-one with the two worm gears 23. The first clearance adjustment mechanism is located at the end of the worm gear 23 away from the coupling 25. The first clearance adjustment mechanism includes a second bearing 26, a protective sleeve 27, a first elastic element 28, and an adjusting element 29. The protective sleeve 27 is disposed in the housing 1. The inner ring of the second bearing 26 is fixed to the worm gear 23, and the outer ring of the second bearing 26 is fixed to the protective sleeve 27. The adjusting element 29 is slidably disposed in the housing 1. The first elastic element 28 is disposed between the adjusting element 29 and the protective sleeve 27, and the first elastic element 28 is configured to always have the tendency to push the protective sleeve 27 toward the worm wheel 21. Specifically, the second bearing 26 is press-fitted to the end of the worm 23. The protective sleeve 27 is provided with a first protrusion and a second protrusion. The first protrusion is press-fitted into the housing 1. The first elastic element 28 is disposed in the mounting hole of the housing 1. The adjusting element 29 is threadedly connected to the wall of the mounting hole, and the two ends of the first elastic element 28 abut against the adjusting element 29 and the second protrusion, respectively. By adjusting the adjusting element 29, the elastic force of the first elastic element 28 can be changed. When the worm 23 and the worm wheel 21 wear for a long time and the gap becomes too large, the first elastic element 28 can provide preload to reduce the gap between the worm 23 and the worm wheel 21 and reduce noise. Further, the first elastic element 28 is a compression spring, and the adjusting element 29 is a bolt.

[0042] Optionally, the steering assembly 3 also includes a third bearing 33 and a fourth bearing 34, which are respectively disposed at both ends of the pinion shaft 31. The third bearing 33 is close to the worm gear 21. The outer rings of both the third bearing 33 and the fourth bearing 34 are fixed to the housing 1, and the inner rings of both the third bearing 33 and the fourth bearing 34 are fixed to the pinion shaft 31. This reduces the friction of the pinion shaft 31 and ensures the force of the rack 32. Further, the third bearing 33 is a ball bearing, and the fourth bearing 34 is a needle roller bearing.

[0043] Furthermore, the steering assembly 3 also includes a bearing housing 301 and a pressure ring 302. The bearing housing 301 is fixed inside the housing 1, the outer ring of the third bearing 33 is fixed to the bearing housing 301, and the pressure ring 302 abuts against the third bearing 33 to improve the stability of the third bearing 33.

[0044] Optionally, the steering assembly 3 also includes a gear 35, which is fixedly sleeved on the pinion shaft 31. The gear 35 is provided with drive teeth that mesh with the rack 32.

[0045] Optionally, the steering assembly 3 further includes a second clearance adjustment mechanism, which includes a fifth bearing 36, a second elastic element 37, and an adjusting plug 38. The fifth bearing 36 is slidably disposed on the housing 1, and one end of the fifth bearing 36 abuts against the end of the rack 32 away from the pinion shaft 31. The adjusting plug 38 is slidably disposed on the housing 1, and the second elastic element 37 is disposed at the other end of the adjusting plug 38 abutting against the fifth bearing 36. The second elastic element 37 is configured to always have a tendency to push the fifth bearing 36 toward the pinion shaft 31. Specifically, since the gear 35 and the rack 32 will wear during continuous meshing, resulting in clearance and noise, the fifth bearing 36 is pressed against the back of the rack 32 teeth. The second elastic element 37 is disposed in the mounting hole of the housing 1, and the adjusting plug 38 is threadedly connected to the wall of the mounting hole. By adjusting the adjusting plug 38, the second elastic element 37 obtains a suitable elastic force, thereby pushing the fifth bearing 36 to squeeze the rack 32, reducing the clearance between the gear 35 and the rack 32, and reducing noise. Furthermore, the second elastic element 37 is a compression spring, the fifth bearing 36 is a sliding bearing, and the fifth bearing 36 is provided with an arc-shaped surface that fits against the back of the teeth of the rack 32.

[0046] Optionally, the second gap adjustment mechanism also includes a buffer pad 39, which is disposed between the fifth bearing 36 and the adjusting plug 38 to prevent the fifth bearing 36 and the adjusting plug 38 from colliding directly and being damaged, thereby improving the service life of the fifth bearing 36 and the adjusting plug 38.

[0047] Optionally, the second clearance adjustment mechanism further includes a plurality of buffer rings 303, which are spaced apart along the length of the fifth bearing 36 and fitted onto the outer periphery of the fifth bearing 36. The buffer rings 303 abut against the wall of the mounting hole, preventing the fifth bearing 36 from colliding with the wall of the mounting hole. Further, a plurality of mounting grooves 361 are provided on the outer periphery of the fifth bearing 36, each corresponding to one of the buffer rings 303. Some of the buffer rings 303 are disposed within the mounting grooves 361, improving the stability of the buffer rings 303.

[0048] Optionally, the second gap adjustment mechanism also includes a sealing ring 304, which is disposed between the adjusting plug 38 and the wall of the mounting hole to improve sealing.

[0049] Optionally, the steering actuator also includes an angle sensor connected to the worm gear 21, which detects the rotation angle of the worm gear 21 and calculates the position of the rack 32. The steering actuator also includes a position sensor located on the drive unit 22, which is communicatively connected to the drive unit 22. The position sensor detects the rotation angle of the motor and calculates the position of the rack 32. Specifically, an angle and position sensor are located at the worm gear 21, and each drive unit 22 has a position sensor and a corresponding controller. Both drive units 22 are connected to independent power supplies from the vehicle to improve safety and ensure that if one fails, the other can still function normally. The CAN 1 of the drive unit 22 is connected to the CAN 1 of the hand-feel simulator; the CAN 2 of the drive unit 22 is connected to the CAN 2 of the hand-feel simulator; the ECU1 and ECU2 of the drive unit 22 communicate via a private CAN bus. It should be noted that CAN refers to the controller area network, and ECU refers to the electronic control unit.

[0050] The working process of the steering actuator provided by this utility model is as follows:

[0051] The angle position sensor transmits the position signal of rack 32 to the electronic control units of the two drive components 22. The electronic control units of drive components 22 receive the position signal from the same worm gear 21. Based on the position signal, the electronic control units of drive components 22 provide corresponding torque and speed. The torque of drive component 22 drives gear 35 and rack 32 through worm gear 21 and worm 23, thereby pushing the wheel to achieve steering. The force signal of rack 32 on the steering gear is transmitted to the hand feel simulator. The hand feel simulator provides reaction force to simulate hand feel. When the user turns the steering wheel, the system predicts the position of rack 32 in the next timing sequence through the line angle transmission ratio of gear 35 and rack 32, and transmits the signal to the angle position sensor. Thus, the system knows the position of rack 32 in the next timing sequence. The position sensor transmits the signal to the ECU of drive component 22, thereby driving component 22 to provide driving force, and so on iteratively.

[0052] The position sensor at drive component 22 calculates the position of rack 32 based on the motor rotation angle and calibrates it with the signal from the angle position sensor. When the calibration deviation is large, it reminds the driver to pull over. The position sensors at the two drive components 22 exchange signals via CAN. When the position indicated by the signal deviates significantly, a fault code will also appear to remind the driver and improve safety.

[0053] Furthermore, the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A steering actuator, characterized in that, include: Shell (1); The drive assembly (2) includes a worm gear (21), two drive members (22) and two worms (23). The two drive members (22) are arranged in a one-to-one correspondence with the two worms (23). The drive members (22) are installed on the housing (1). The worms (23) are rotatably connected to the housing (1). The drive members (22) are connected to the worms (23) in a transmission connection. The drive members (22) can drive the worms (23) to rotate. The worm gear (21) is rotatably connected to the housing (1). The two worms (23) are respectively arranged on both sides of the worm gear (21). The two worms (23) mesh with the same set of teeth of the worm gear (21). The steering assembly (3) includes a pinion shaft (31) and a rack (32). The pinion shaft (31) is coaxially fixed to the worm gear (21). The outer wall of the pinion shaft (31) is provided with driving teeth. The driving teeth mesh with the rack (32). The rack (32) is slidably connected to the housing (1). The rack (32) is connected to the wheel through a tie rod. The driving teeth can drive the rack (32) to move, thereby pushing the wheel to rotate.

2. The steering actuator according to claim 1, characterized in that, The drive assembly (2) further includes two first bearings (24), which are arranged in a one-to-one correspondence with the two worm gears (23). The outer ring of the first bearing (24) is fixed to the housing (1), and the inner ring of the first bearing (24) is fixed to the worm gear (23).

3. A steering actuator according to claim 1, characterized in that, The drive assembly (2) further includes two couplings (25), which are arranged one-to-one with the two drive components (22), and the couplings (25) are disposed between the drive component (22) and the worm gear (23).

4. A steering actuator according to claim 3, characterized in that, The drive assembly (2) further includes two first clearance adjustment mechanisms, which are respectively arranged in correspondence with the two worm gears (23). The first clearance adjustment mechanism is located at the end of the worm gear (23) away from the coupling (25). The first clearance adjustment mechanism includes a second bearing (26), a protective sleeve (27), a first elastic element (28), and an adjusting element (29). The protective sleeve (27) is located in the housing (1). The inner ring of the second bearing (26) is fixed to the worm gear (23), and the outer ring of the second bearing (26) is fixed to the protective sleeve (27). The adjusting element (29) is slidably located in the housing (1). The first elastic element (28) is located between the adjusting element (29) and the protective sleeve (27), and the first elastic element (28) is configured to always have a tendency to push the protective sleeve (27) toward the worm wheel (21).

5. A steering actuator according to claim 1, characterized in that, The steering assembly (3) further includes a third bearing (33) and a fourth bearing (34), which are respectively disposed at both ends of the pinion shaft (31), and the third bearing (33) is close to the worm gear (21). The outer rings of the third bearing (33) and the fourth bearing (34) are both fixed to the housing (1), and the inner rings of the third bearing (33) and the fourth bearing (34) are both fixed to the pinion shaft (31).

6. A steering actuator according to claim 1, characterized in that, The steering assembly (3) further includes a gear (35), which is sleeved on the pinion shaft (31) and has the drive teeth.

7. A steering actuator according to claim 6, characterized in that, The steering assembly (3) further includes a second clearance adjustment mechanism, which includes a fifth bearing (36), a second elastic element (37), and an adjusting plug (38). The fifth bearing (36) is slidably disposed on the housing (1), and one end of the fifth bearing (36) abuts against the end of the rack (32) away from the pinion shaft (31). The adjusting plug (38) is slidably disposed on the housing (1). The second elastic element (37) is disposed at the other end of the adjusting plug (38) abutting against the fifth bearing (36), and the second elastic element (37) is configured to always have a tendency to push the fifth bearing (36) toward the pinion shaft (31).

8. A steering actuator according to claim 7, characterized in that, The second gap adjustment mechanism also includes a buffer pad (39), which is disposed between the fifth bearing (36) and the adjusting plug (38).

9. A steering actuator according to any one of claims 1-8, characterized in that, The steering actuator further includes an angle sensor connected to the worm gear (21) and used to detect the rotation angle of the worm gear (21).

10. A steering actuator according to any one of claims 1-8, characterized in that, The steering actuator further includes a position sensor, which is disposed on the drive member (22) and is communicatively connected to the drive member (22). The position sensor is used to detect the rotation angle of the drive member (22) and thereby calculate the position of the rack (32).

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