Steering execution module of steer-by-wire system and steer-by-wire system

Abstract

The utility model provides a steering execution module of a steering-by-wire system and the steering-by-wire system comprising the steering execution module. The steering execution module comprises an outer shell and a steering gear installed in the outer shell. The steering gear comprises a gear and a rack which are meshed with each other. The steering execution module further comprises a magnetostrictive displacement sensor. The magnetostrictive displacement sensor comprises a sensor body and a position magnet, one of the sensor body and the position magnet is fixedly installed on the outer shell, and the other one of the sensor body and the position magnet is fixedly installed on the rack. According to the steering execution module, a sensor tower ST and a steering gear used for a traditional electric power steering system are omitted, and a low-cost solution for measuring the actual steering angle of the wheel is provided.

Description

Technical Field

[0001] The present disclosure relates to the field of vehicles, and more particularly to a steering execution module of a steer-by-wire system of a vehicle and a steer-by-wire system including the steering execution module. Background Art

[0002] Steer-by-Wire is an advanced automotive steering technology that controls the steering of the car through electronic signals rather than traditional mechanical connections. This technology eliminates the mechanical connection between the steering wheel and the wheels, and instead uses electronic signals to transmit the driver's steering intentions and directly controls the steering angle of the wheels through electronic actuators.

[0003] In the current steering execution module of the wire control steering system, such as Figure 1 As shown, a sensor tower (SensorTower) ST is used as a position feedback sensor to monitor the actual steering angle of the wheel to achieve closed-loop control. Specifically, the sensor tower ST includes an angle sensor with high accuracy. The angle sensor can measure the position of the steering gear (not shown in the figure), and then obtain the actual steering angle of the wheel through the position of the steering gear. The steering gear is part of a traditional electric power steering (Electric Power Steering) system, which is used to mechanically transmit the steering torque from the steering wheel to the wheel to achieve wheel steering.

[0004] However, for the steer-by-wire system, since the mechanical connection between the steering wheel and the wheel is eliminated, the steering gear is no longer needed. If the steering gear is retained only for the purpose of monitoring the actual steering angle of the wheel, it will lead to unnecessary cost expenditure. Among them, leaving aside the cost of the sensor tower ST, the cost of a steering gear alone is about 200 yuan. Utility Model Content

[0005] In order to solve the problems pointed out in the background technology, the utility model proposes a new steering execution module of a wire-controlled steering system, which omits the sensor tower ST and the steering gear used in the traditional electric power steering system, and instead adopts a relatively low-cost magnetostrictive displacement sensor to monitor the actual steering angle of the wheel. The magnetostrictive displacement sensor can be easily installed in the steering execution module, and measures the electrical signal associated with the displacement of the rack of the steering execution module in a magnetic way, thereby obtaining the actual steering angle of the wheel. In addition, the magnetostrictive displacement sensor can measure with high precision, high stability and high reliability.

[0006] According to one embodiment of the present disclosure, a steering execution module of a wire-controlled steering system is proposed, the steering execution module comprising: an outer shell; and a steering gear installed in the outer shell, the steering gear comprising a gear and a rack that mesh with each other, the steering execution module also includes a magnetostrictive displacement sensor, the magnetostrictive displacement sensor comprising: a sensor body; and a position magnet, wherein one of the sensor body and the position magnet is fixedly mounted on the outer shell, and the other is fixedly mounted on the rack.

[0007] In one embodiment, the sensor body is fixedly mounted on the inner wall of the outer shell, and the position magnet is embedded in the rack.

[0008] In one embodiment, the sensor body includes: a current pulse generator configured to generate a current pulse; a waveguide wire, the current pulse propagates along the waveguide wire and forms an annular transient magnetic field around the waveguide wire, and the waveguide wire is configured to form a torsional wave propagating forward and backward along the waveguide wire when the annular transient magnetic field meets the magnetic field formed by the position magnet; and a detection coil configured to detect the torsional wave transmitted backward.

[0009] In one embodiment, the sensor body further comprises a damper configured to attenuate the forwardly transmitted torsional wave.

[0010] In one embodiment, the sensor body further comprises a magnetic encoder configured to form, together with the position magnet, a magnetic field for interacting with the annular transient magnetic field.

[0011] In one embodiment, the waveguide wire is located in a magnetic field formed by the magnetic encoder and the position magnet.

[0012] In one embodiment, the magnetic encoder comprises a series of magnets arranged along the length of the waveguide wire.

[0013] In one embodiment, the S pole of the preceding magnet is connected to the N pole of the succeeding magnet, or the N pole of the preceding magnet is connected to the S pole of the succeeding magnet.

[0014] According to another embodiment of the present disclosure, a steer-by-wire system is provided, wherein the steer-by-wire system comprises a steering execution module according to any one of the above items.

[0015] In one embodiment, the steer-by-wire system further includes: a steering wheel module; and a central control unit, wherein the steering wheel module is configured to sense a driver's steering input and send the steering input to the central control unit, and the central control unit is configured to generate a control signal based on the steering input and send the control signal to the steering execution module.

[0016] In general, the various embodiments of the present disclosure may be combined and coupled in any possible manner within the scope of the present disclosure. These and other aspects, features and / or advantages of the present disclosure will be apparent and elucidated with reference to the embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments of the present disclosure will be described by way of example with reference to the following drawings, in which:

[0018] Figure 1 The schematic diagram shows a steering execution module of a conventional steer-by-wire system, wherein a sensor tower ST is used in conjunction with a steering gear to measure an actual steering angle of a vehicle;

[0019] Figure 2 The steer-by-wire system according to one embodiment of the present disclosure is schematically shown, wherein the sensor tower ST and the steering gear are omitted, and a magnetostrictive displacement sensor 30 is used instead to measure the actual steering angle of the vehicle;

[0020] Figure 3 The structure and arrangement of the magnetostrictive displacement sensor 30 of the steering execution module are schematically shown;

[0021] Figure 4 and Figure 5 The working process of the magnetostrictive displacement sensor 30 is schematically shown.

[0022] It should be understood that the drawings only illustrate one way of implementing the present disclosure and should not be construed as limiting other possible embodiments that fall within the scope of protection of the appended claims. The scope of protection of the present disclosure is limited only by the appended claims. DETAILED DESCRIPTION

[0023] The automobile steering system has gone through several stages: mechanical steering system, hydraulic power steering system, electro-hydraulic power steering system and electric power steering system, and is currently developing towards a wire-controlled steering system.

[0024] Figure 1 The schematic diagram shows a steering execution module of a wire-controlled steering system in the prior art. As described in the background technology section, the steering execution module uses a sensor tower ST to cooperate with a steering gear to monitor the actual steering angle of the wheel.

[0025] Figure 2 The figure schematically shows a steer-by-wire system according to an embodiment of the present disclosure. Figure 2 As shown in FIG. 1 , the wire-controlled steering system according to the present disclosure includes three parts: a steering wheel module 1; a steering execution module 2; and a central control unit (ECU) 3. The steering wheel module 1 is responsible for sensing the steering input of the driver on the steering wheel and sending the input to the ECU 3. The ECU 3 generates a control signal based on the received input and sends the control signal to the steering execution module 2. The steering execution module 2 controls the wheels to steer based on the received control signal. Compared with the prior art, the wire-controlled steering system of the present invention is more convenient to use. Figure 2 In the steering execution module 2 shown, the sensor tower ST and the steering gear are omitted, and a magnetostrictive displacement sensor 30 is used instead to measure the actual steering angle of the vehicle.

[0026] Continue to refer to Figure 2 The components of the steering execution module 2 and their relative positional relationships are described in detail. The steering execution module 2 includes a motor module 20 , a steering gear 24 and a steering tie rod 27 .

[0027] The motor module 20 includes a motor controller 21, a steering motor 22 and a reducer 23. The motor controller 21 is used to receive a control signal sent by the ECU 3, and based on the control signal, controls the operation of the steering motor 22 to ensure that the steering motor 22 operates at the desired steering angle. The steering motor 22 is usually a permanent magnet synchronous motor, which is responsible for providing the desired speed under the control of the motor controller 21. The reducer 23 is used to reduce the speed of the steering motor 22 and increase the output torque to meet the steering requirements.

[0028] The steering gear 24 is connected to the output end of the motor module 20, and its function is to convert the rotational motion provided by the motor module 20 into linear motion. The steering gear 24 can be a gear rack structure. The output end of the reducer 23 drives the gear 25 of the steering gear 24 (refer to Figure 3 ), then the gear 25 drives the rack 26 meshing therewith (reference Figure 3 ), thereby converting the rotational motion of the gear 25 into the linear motion of the rack 26.

[0029] The steering rod 27 is connected to the output end of the steering gear 24, specifically connected to the rack 26 of the steering gear 24. The other end of the steering rod 27 is connected to the wheel (not shown in the figure) to transmit the linear motion generated by the steering gear 24 to the wheel, thereby achieving the steering of the wheel. As an example, Figure 2 Only the right side tie rod 27 is shown, but a person skilled in the art will appreciate that there will be a symmetrically arranged tie rod on the left side.

[0030] like Figure 2As shown, the motor module 20 and the steering gear 24 can be disposed in the outer housing 28 (therefore, in Figure 2 In the figure, only the approximate positions of the motor module 20 and the steering gear 24 are schematically indicated, and the above-mentioned specific structure is not shown). Both ends of the outer shell 28 can be connected with a retractable rubber bellows 29 (only a part of the rubber bellows on the left is shown) to accommodate the linear movement of the rack 26 of the steering gear 24 within a certain range.

[0031] In addition, the steering execution module 2 according to an embodiment of the present disclosure further includes a magnetostrictive displacement sensor 30. The magnetostrictive displacement sensor 30 is configured to measure an electrical signal associated with the displacement of the rack 26, and send the measured electrical signal as a feedback signal to the ECU 3. Subsequently, the ECU 3 can calculate the actual steering angle of the wheel based on the feedback signal, and can achieve closed-loop control of the steering operation by comparing the actual steering angle with the expected steering angle.

[0032] Figure 3 The structure and arrangement of the magnetostrictive displacement sensor 30 of the steering execution module are schematically shown. Figure 3 As described above, the magnetostrictive displacement sensor 30 includes a sensor body 31 and a position magnet 32. Figure 3 In the embodiment shown, the sensor body 31 is fixedly mounted on the outer shell 28 ( Figure 3 The position magnet 32 ​​is fixedly mounted on the rack 26. It will be understood that the opposite arrangement is also possible, that is, the position magnet 32 ​​is fixedly mounted on the outer shell 28, and the sensor body 31 is fixedly mounted on the rack 26. In a preferred embodiment, the sensor body 31 is fixedly mounted on the inner wall of the outer shell 28, and the position magnet 32 ​​is embedded in the rack 26.

[0033] The following is still for reference Figure 3 The components of the sensor body 31 are described in detail. Figure 3As shown, the sensor body 31 can generally include a current pulse generator 33, a waveguide wire 34, a detection coil 35 and a damping 36. The above components can be packaged together in a plastic housing to form a whole. The current pulse generator 33 is configured to generate current pulses, which propagate along the waveguide wire 34 and form a circular transient magnetic field around the waveguide wire 34. By accurately controlling the frequency and amplitude of the current pulse, the measurement accuracy of the magnetostrictive displacement sensor 30 can be optimized. The waveguide wire 34 is the core part of the magnetostrictive displacement sensor, which is made of magnetostrictive material. The waveguide wire 34 is used to transmit the current pulse and the transient magnetic field generated by it, and generates a magnetostrictive effect when the transient magnetic field meets the magnetic field formed by the position magnet 32, that is, a local deformation occurs. The local deformation of the waveguide wire 34 causes the magnetic domains inside it to be rearranged. Since the rearrangement of the magnetic domains is usually carried out along the length direction of the waveguide wire 34, this arrangement change will generate a mechanical torsion in the waveguide wire material, thereby forming a torsion wave that propagates forward and backward along the waveguide wire 34. The detection coil 35 is wrapped around a portion of the waveguide wire 34 and is arranged at approximately the same end of the waveguide wire 34 as the current pulse generator 33. The detection coil 35 is configured to detect the torsional wave that is transmitted back (i.e., propagating backward along the waveguide wire 34). Specifically, when the torsional wave that is transmitted back propagates to the position where the detection coil 35 is located, the magnetic induction intensity in the waveguide wire 34 changes, resulting in an induced voltage at both ends of the coil. The time difference between this induced voltage (termination pulse) and the start pulse generated by the current pulse generator 33 is used to calculate the displacement. The damping 36 is arranged at the other end of the waveguide wire 34 relative to the detection coil 35 and the current pulse generator 33. It attenuates the energy of the torsional wave that propagates forward along the waveguide wire 34 (i.e., it will not be detected by the detection coil 35), thereby reducing or eliminating its reflection and reverberation, so as to ensure that only the torsional wave that is transmitted back is detected.

[0034] In a preferred embodiment, the sensor body 31 may further include a magnetic encoder 37. The magnetic encoder 37 includes a series of magnets arranged along the length direction of the waveguide wire 34, wherein the S pole of the previous magnet is connected to the N pole of the next magnet (or the N pole of the previous magnet is connected to the S pole of the next magnet), thereby forming a NSNSNSNS... (or SNSNSNSN...) magnetic pole arrangement structure. The magnetic sensor 37 is configured to interact with the position magnet 32 ​​to jointly form a stronger magnetic field to replace the weaker magnetic field generated by the position magnet 32 ​​alone. Thus, even if the distance between the outer shell 28 and the rack 26 is large (for example, more than 4 mm), the magnetostrictive displacement sensor 30 can accurately measure the displacement of the rack 26. In addition, the magnetostrictive displacement sensor 30 including the magnetic encoder 37 is also more resistant to interference. If the magnetic encoder 37 is not provided, the measurement accuracy will be greatly reduced, or even measurement may not be possible, simply relying on the magnetic field of the position magnet 32 ​​itself to interact with the waveguide wire 34. After the sensor body 31 and the position magnet 32 ​​are installed, the waveguide wire 34 is located between the magnetic encoder 37 and the position magnet 32, that is, the waveguide wire 34 is located in the magnetic field formed by the magnetic encoder 37 and the position magnet 32. In this way, the strong magnetic field formed by the magnetic encoder 37 and the position magnet 32 ​​can be used to interact with the waveguide wire 34.

[0035] The following will refer to Figure 4 and Figure 5 The working process of the above-mentioned magnetostrictive displacement sensor 30 is described in detail. First, the current pulse generator 33 emits current pulses at a fixed frequency, and these current pulses propagate along the waveguide wire 34, forming an annular instantaneous magnetic field F1 around the waveguide wire 34. The annular instantaneous magnetic field F1 propagates along the waveguide wire 34 together with the current pulses. The position magnet 32 ​​moves left and right with the movement of the rack 26 (as shown by the arrow A in the figure), and forms a stronger magnetic field F2 together with the magnetic encoder 37. When the annular instantaneous magnetic field F1 meets the stronger magnetic field F2 (as shown in the figure), the position magnet 32 ​​moves left and right with the movement of the rack 26 (as shown in the figure by the arrow A), and forms a stronger magnetic field F2 together with the magnetic encoder 37. Figure 5 As shown in the figure, a torsional wave W will be formed in the waveguide wire 34 and will be transmitted back along the waveguide wire 34. The torsional wave W propagates back and is detected by the detection coil 35. Since the propagation speed of the current pulse / torsion wave in the waveguide wire 34 is known, the position or displacement of the position magnet 32 ​​can be calculated by using the time difference between the detection coil 35 detecting the torsional wave W and the current pulse generator 33 emitting the current pulse. During the measurement process, the current pulse generator 33 will continuously emit current pulses, so the magnetostrictive displacement sensor 30 can measure the position or displacement of the position magnet 32 ​​in real time with high resolution. Based on the measured position or displacement of the position magnet 32, the real-time steering angle of the wheel can be calculated.

[0036] It will be appreciated that the lengths of the waveguide wire 34 and the magnetic encoder 37 may be appropriately selected so that the magnetostrictive displacement sensor 30 is suitable for measuring the position or displacement of the position magnet 32 ​​corresponding to the entire steering angle range of the wheel.

[0037] Although the present disclosure has been described in conjunction with the above-mentioned specific embodiments, it should not be understood as being limited to the examples presented in any way. The scope of the present disclosure is defined by the appended claims. In the context of the claims, the terms "comprise" or "include" do not exclude other possible elements or steps. In addition, references such as "one" or "an" should not be interpreted as excluding multiple. The use of reference symbols for elements shown in the figures in the claims should not be interpreted as limiting the scope of the present disclosure. In addition, the various features mentioned in different claims may be advantageously combined, and the mention of these features in different claims does not exclude that the combination of these features is impossible and advantageous. In addition, the "first", "second", etc. used in the present disclosure are only used to distinguish the relevant components, and are not intended to give them any priority attributes.

Claims

1. A steering execution module (2) of a steer-by-wire system, the steering execution module (2) comprising: An outer shell (28); and a steering gear (24) installed in the outer shell (28), the steering gear (24) comprising a gear (25) and a rack (26) meshing with each other, Characterized in that the steering execution module (2) further comprises a magnetostrictive displacement sensor (30), and the magnetostrictive displacement sensor (30) comprises: a sensor body (31); and Position magnet (32), Wherein, one of the sensor body (31) and the position magnet (32) is fixedly mounted on the outer shell (28), and the other is fixedly mounted on the rack (26).

2. The steering execution module (2) according to claim 1, characterized in that: The sensor body (31) is fixedly mounted on the inner wall of the outer shell (28), and the position magnet (32) is embedded in the rack (26).

3. The steering execution module (2) according to claim 1 or 2, characterized in that: The sensor body (31) comprises: a current pulse generator (33), the current pulse generator (33) being configured to generate current pulses; a waveguide wire (34), the current pulse propagating along the waveguide wire (34) and forming an annular transient magnetic field around the waveguide wire (34), and the waveguide wire (34) is configured to form a torsional wave propagating forward and backward along the waveguide wire (34) when the annular transient magnetic field meets the magnetic field formed by the position magnet (32); and A detection coil (35) is configured to detect the backward transmitted torsional wave.

4. The steering execution module (2) according to claim 3, characterized in that: The sensor body (31) also includes a damper (36) configured to attenuate the forwardly transmitted torsional wave.

5. The steering execution module (2) according to claim 3, characterized in that: The sensor body (31) further comprises a magnetic encoder (37) configured to form, together with the position magnet (32), a magnetic field for interacting with the annular instantaneous magnetic field.

6. The steering execution module (2) according to claim 5, characterized in that: The waveguide wire (34) is located in a magnetic field formed by the magnetic encoder (37) and the position magnet (32).

7. The steering execution module (2) according to claim 5, characterized in that: The magnetic encoder (37) comprises a series of magnets arranged along the length direction of the waveguide wire (34).

8. The steering execution module (2) according to claim 7, characterized in that: The S pole of the previous magnet is connected to the N pole of the next magnet, or the N pole of the previous magnet is connected to the S pole of the next magnet.

9. A steer-by-wire system, characterized in that: The steer-by-wire system comprises a steering actuation module (2) according to any one of claims 1-8.

10. The steer-by-wire system according to claim 9, characterized in that: The steer-by-wire system further comprises: a steering wheel module (1); and Central control unit (3), The steering wheel module (1) is configured to sense the driver's steering input and send the steering input to the central control unit (3); the central control unit (3) is configured to generate a control signal based on the steering input and send the control signal to the steering execution module (2).

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