A steering wheel angle detection device with redundant safety device

Abstract

In response to the safety issues of wire-controlled steering systems, a steering wheel angle detection device with redundant safety devices is provided, which includes a hydraulic cylinder, a bearing, an active piston, a driven fork, a limit sliding device, a connecting shaft, a spring, a cylindrical cam, a sealed bearing, a driven piston, a sensing detection shaft, a displacement detection device, and an unlocking component; the hydraulic cylinder is provided with two cavities, a large cavity and a detection cavity, and the large cavity and the detection cavity are connected by a flow channel; a cylindrical cam is provided in the large cavity, and a connecting shaft is connected to the cylindrical cam through a spring. In an emergency, the connecting shaft descends to form a mechanical connection with the transmission system, and a driven piston is provided in the detection cavity, and the sensing detection shaft is connected to the driven piston; the present invention adds a set of safety transpositions, which can realize the mechanical connection between the steering wheel and the wire-controlled chassis in an emergency, greatly improving driving safety.

Description

Technical Field

[0001] The present invention relates to the field of steering wheel angle detection devices, and in particular to a steering wheel angle detection device with a redundant safety device. Background Art

[0002] With the rapid development of new energy vehicles, steer-by-wire systems for these vehicles are gaining widespread adoption. A steer-by-wire system uses hydraulics or auxiliary power to control vehicle steering via electrical signals, replacing the mechanical connection between the steering wheel and steering column. To obtain electrical signals representing steering wheel angles, steering wheel angle sensors play an irreplaceable role. These sensors not only measure steering wheel angles but also provide the necessary steering wheel angle signals for the vehicle's active safety systems. Popular technologies that enhance vehicle safety and driving experience, such as the Electronic Stability Program (ESP), Electric Power Steering (EPS), and Adaptive Front Lighting (AFS), all rely on steering wheel angles for their implementation.

[0003] Currently, steering wheel angle sensors utilize three types: potentiometer, electromagnetic coil, and magnetic chip. Potentiometer sensors, patented by BI (USA), operate based on the sliding rheostat principle and output absolute steering wheel angle signals. However, their contact-type operation severely impacts device lifespan and signal noise. Electromagnetic coil sensors, patented by Hell (Germany), require an angle chip in addition to the electromagnetic coil to measure absolute steering wheel angle. Magnetic chip angle sensors, primarily patented by BOSCH (Germany), utilize the incremental method to only output relative angle signals, while the differential method allows for direct absolute angle output. However, calculating the differential angle and determining direction increases the workload of the logic processing unit. These implementations often utilize a transmission element to amplify the measured angle with a transmission ratio greater than 1 to improve detection accuracy. The physical quantity detected is always a rotational angle. This invention designs a conversion mechanism to convert the measured angle into a displacement.

[0004] The steer-by-wire system eliminates the mechanical connection between the vehicle's steering wheel and steering wheel. Although it has many advantages, such as taking up less space and reducing damage to the driver in the event of a collision, the steer-by-wire system improves the vehicle's rotation efficiency and shortens the system's response time, due to the current immaturity of technology or imperfect manufacturing processes, the electronic control unit may misjudge the vehicle's driving status or produce fatal errors, posing a great threat to the vehicle's driving safety. Summary of the Invention

[0005] To address the above-mentioned drawbacks, the present invention further incorporates a mechanical connection mechanism into the mechanism for detecting physical quantity conversion, which can establish a mechanical connection between the steering wheel and the steering column in a short period of time, thereby enhancing the safety of the steering system.

[0006] The present invention provides a steering wheel angle detection device with a redundant safety device, comprising: a hydraulic cylinder 3, a driven fork 8, a limit sliding device 9, and a cylindrical cam 12;

[0007] The hydraulic cylinder body 3 is provided with two cavities, a large cavity 18 and a detection cavity 16, which are connected by a flow channel 17;

[0008] The cylindrical cam 12 is disposed in the large cavity 18; the upper end of the cylindrical cam 12 is the input shaft.

[0009] The input shaft is rotatably and sealedly connected to the hydraulic cylinder body 3;

[0010] A connecting shaft 10 is provided inside the cylindrical cam 12, and the connecting shaft 10 and the cylindrical cam 12 cannot rotate relative to each other;

[0011] An unlocking assembly is mounted on the hydraulic cylinder body 3, and the connecting shaft 10 cooperates with the unlocking assembly. When the unlocking assembly is in an unlocked state, the connecting shaft 10 can generate relative movement with the cylindrical cam 12 in the vertical direction. When the unlocking assembly is in a locked state, the connecting shaft 10 cannot generate relative movement with the cylindrical cam 12.

[0012] The upper end of the driven fork 8 is a fork tip, the lower end of the driven fork 8 is a fork handle, and the fork tip is connected to the cylindrical cam 12 through the limiting sliding device 9;

[0013] The inner wall of the large cavity 18 is provided with a sliding groove along the axial direction of the cylindrical cam 12, one end of the limiting sliding device 9 is embedded in the sliding groove, and the other end of the limiting sliding device 9 is equipped with a rolling bearing, which is installed in the contour of the cylindrical cam 12;

[0014] The fork handle of the driven fork 8 is fixedly connected to the active piston 6;

[0015] A slave piston 19 is provided in the detection chamber 16, and the sensing detection shaft 20 is connected to the slave piston 19;

[0016] The hydraulic cylinder body 3 is provided with a displacement detection device 22 ; the sensing detection shaft 20 passes through the displacement detection device 22 .

[0017] Preferably, the upper end of the connecting shaft 10 includes a limiting shaft, the cross section of the limiting shaft is non-circular, and the inner wall of the cylindrical cam 12 is also provided with a limiting area with a non-circular cross section. The limiting shaft cooperates with the limiting area so that the connecting shaft 10 and the cylindrical cam 12 cannot rotate relative to each other.

[0018] Preferably, the unlocking assembly comprises: a fastening nut 2, an electromagnet 23, a pin 24 and a pin spring 1;

[0019] A spring 11 is provided inside the cylindrical cam 12, the upper end of the spring 11 is connected to the upper wall inside the cylindrical cam 12, and the lower end of the spring 11 is connected to the connecting shaft 10;

[0020] The fastening nut 2 is located at the lower part of the large cavity 18. The fastening nut 2 is threadedly connected to the hydraulic cylinder body 3. The fastening nut 2 is a hollow structure. The lower part of the connecting shaft 10 passes through the fastening nut 2.

[0021] The lower portion of the connecting shaft 10 is provided with an annular groove, and the side wall of the fastening nut 2 is provided with a through hole. One end of the pin 24 is inserted into the annular groove at the lower portion of the connecting shaft 10 through the through hole, and the other end of the pin 24 is connected to the electromagnet 23 through the pin spring 1;

[0022] The electromagnet 23 is fixedly connected to the hydraulic cylinder 3 .

[0023] Preferably, a driving gear 14 and a driven gear 15 are further provided at the upper end of the cylindrical cam 12;

[0024] The driving gear 14 is fixedly connected to the input shaft of the cylindrical cam 12 , and the driven gear 15 is meshed with the driving gear 14 . The driven gear 15 is magnetic. A Hall chip is provided on the hydraulic cylinder body 3 , and the Hall chip is located opposite to the driven gear 15 .

[0025] Preferably, the cross-sectional area of the detection cavity 16 is 1 / 4 of the large cavity 18 .

[0026] Preferably, the sensing shaft 20 is made of a transparent material, and the surface of the sensing shaft 20 is densely covered with uniform indentations and the indentations are coated with black pigment;

[0027] The displacement detection device 22 includes an annular through hole, a spotlight is installed on the inner wall of one side of the annular through hole, and a photosensor is installed on the other side illuminated by the spotlight; the photosensor detects the movement distance of the driven piston 19 by counting the number of dark lights.

[0028] Preferably, a limiting nut 21 is further provided at the lower portion of the detection chamber 16 .

[0029] Preferably, the input shaft is rotatably and sealedly connected to the hydraulic cylinder body 3 via a sealed bearing 13:

[0030] The sealed bearing 13 is located at the upper end of the large cavity 18, the inner ring of the sealed bearing 13 is rotatably sealed and connected to the upper end of the cylindrical cam 12, and the outer ring of the sealed bearing 13 is fixedly connected to the hydraulic cylinder body 3;

[0031] A bearing 4 is provided at the lower end of the large cavity 18 , and the bearing 4 is fixedly connected to the hydraulic cylinder body 3 . The lower portion of the connecting shaft 10 passes through the bearing 4 and extends out of the cylindrical cam 12 .

[0032] Preferably, a plurality of mounting holes are provided on the fork handle of the driven fork 8 and the active piston 6, and the driven fork 8 and the active piston 6 are fixedly connected by inserting a plurality of mounting pins 7 into the mounting holes on the active fork 8 and the active piston 6; a sealing ring 5 is also installed on the outside of the active piston 6.

[0033] The beneficial effects of the present invention include:

[0034] 1. A cylindrical cam mechanism was designed and used in the automotive steer-by-wire system, which can convert the rotational motion of the steering wheel into reciprocating linear motion.

[0035] 2. A new steering wheel angle measurement method is proposed. Two hydraulic cylinders with different cross-sectional areas are used to convert the small displacement of the master cylinder into the large displacement of the slave lever to improve the detection accuracy. The measurement method of this device is changed from the angle measurement of the traditional steering wheel angle sensor to the displacement measurement of the slave hydraulic cylinder.

[0036] 3. Adding a set of safety transpositions can achieve mechanical connection between the steering wheel and the wire-controlled chassis in an emergency, greatly improving driving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the specific embodiments or the description of the prior art. Hereinafter, some specific embodiments of the present invention will be described in detail in an illustrative and non-limiting manner with reference to the drawings. The same reference numerals in the drawings indicate the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0038] Figure 1The device of the embodiment of the present invention is shown, which includes a steering angle detection device and a safety device. The left side shows all the parts, and the right side shows the whole assembly. The numbers in the figure are explained as follows: 1 is a pin spring, 2 is a fastening nut, 3 is a hydraulic cylinder, 4 is a bearing, 5 is a sealing ring, 6 is an active piston, 7 is a mounting pin, 8 is a driven fork, 9 is a limit sliding device, 10 is a connecting shaft, 11 is a spring, 12 is a cylindrical cam, 13 is a sealed bearing, 14 is a driving gear, 15 is a driven gear, 19 is a driven piston, 20 is a sensing shaft, 21 is a limit nut, 22 is a displacement detection device, 23 is an electromagnet, and 24 is a pin.

[0039] Figure 2 2 is a cross-sectional view of a device according to an embodiment of the present invention.

[0040] Figure 3 Schematic diagram of the installation position of the device of the present invention.

[0041] Figure 4 Schematic diagram of the connection relationship between the sealing ring, active piston and mounting pin.

[0042] Figure 5 It is a schematic diagram of the cylindrical cam mechanism, with the assembly relationship diagram on the left and the motion diagram on the right.

[0043] Figure 6 Schematic diagram of the displacement detection device. DETAILED DESCRIPTION

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second" and the like are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined as "first", "second" and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0045] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0046] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0047] In the attached Figure 1 The device shown in the figure is a device according to an embodiment of the present invention, which includes both a steering angle detection device and a safety device. The left side shows all the parts, and the right side shows the whole assembly. The complete cross-sectional view is shown in the attached figure. Figure 2 The steering angle detection device is used to detect the angular rotation of the steering shaft. The safety device is used to ensure safety when the electronic control unit misjudges the vehicle's driving state or produces a fatal error. The overall installation position of the device is as shown in the attached Figure 3 The installation position is below the road sensing motor 26 and above the transmission mechanism 27. The input shaft of the steering angle detection device is the upper half shaft section of the cylindrical cam 12. Pins are inserted between the steering shaft to ensure a tight connection. The detection hydraulic cylinder body 3 is fixed to the vehicle frame with bolts.

[0048] The main components of the steering angle detection device are as follows Figure 2 As shown: sealing ring 5, active piston 6, mounting pin 7, cylindrical cam 12, bearing 4 and sealed bearing 13, hydraulic cylinder 3, driven piston 19, sensing shaft 20, driven fork 8, displacement detection device 22, wherein the hydraulic cylinder 3 is the mounting base for the other components. The steering angle detection device of the present invention needs to ensure good sealing to ensure accurate detection results, so it is composed of sealed bearing 13, active piston 6 and driven piston 19 as shown in the attached figure. Figure 2 The large cavity 18 and the detection cavity 16 are connected through the flow channel 17. To ensure the seal, the active piston 6 is equipped with a sealing ring 5. The detailed structure is shown in the attached figure. Figure 4 The sealing bearing 13 and the hydraulic cylinder body 3 adopt an interference fit, and the inner ring of the bearing and the cylindrical cam 12 also adopt an interference fit to seal the large cavity 18.

[0049] This invention proposes a new steering wheel angle measurement method. Using two hydraulic cylinders with different cross-sectional areas, the small displacement of the master cylinder is converted into a large displacement of the slave lever, thereby improving detection accuracy. This device changes the measurement method from the traditional steering wheel angle sensor's angle measurement to the displacement measurement of the slave hydraulic cylinder. To achieve steering angle detection, a cylindrical cam mechanism is designed to convert the rotational motion of the vehicle's steering column into reciprocating displacement motion. As shown in the attached figure, Figure 5 The cylindrical cam 12, along with the driven fork 8, the limit slide 9, and the hydraulic cylinder 3, form a cylindrical cam mechanism. One end of the limit slide 9 is embedded in a groove on the inner wall of the large cavity 18 of the hydraulic cylinder 3. The surfaces of the embedded end and the groove must be machined smooth. The other end is equipped with a small-sized rolling bearing, which fits within the contour of the cylindrical cam 6.

[0050] When the cylindrical cam 12 rotates with the upper steering wheel 25, the limiter slide 9 restricts the axial rotational freedom of the follower fork 8 along the large cavity 18 of the hydraulic cylinder 3, forcing the follower fork 8 to slide axially along the large cavity 18 after receiving the force from the cylindrical cam. At the same time, the installation position of the limiter slide 9 forces its relative motion with the cylindrical cam 12 to follow the pre-designed spatial curve of the cam. The cam profile design must ensure that the vertical movement of the follower is linear with the rotation of the cylindrical cam to facilitate the subsequent conversion of displacement and rotation angle.

[0051] In the angle detection working mode, the cylindrical cam 12 is fixedly connected to the upper steering wheel 25 and rotates with the steering wheel 25. The driven fork 8 slides along the axial direction of the hydraulic cylinder 3 after receiving the force from the cylindrical cam 12. The fluid flow inside the entire invention device is shown in the attached figure. Figure 2 As the active piston 6 reciprocates, fluid flows back and forth between the large cavity 18 of the hydraulic cylinder 3 and the detection cavity 16 through the flow channel 17, forcing the slave piston 19 to reciprocate. To prevent the slave piston 19 from being squeezed out of the detection cavity 16, a limit nut 21 threadedly connected to the hydraulic cylinder 3 is installed below.

[0052] To improve detection accuracy, the present invention utilizes a mechanical structure to convert and amplify the steering shaft rotation angle to be detected. A cylindrical cam mechanism is first used to convert the detected angle into displacement. During this conversion, the 360-degree angle is divided into four reciprocating motions of the active piston 6 using the four peaks and valleys of the cylindrical cam. To amplify small displacements and enhance detection accuracy when liquid flows within the cavity, the cross-sectional area of the detection cavity 16 is designed to be one-fourth that of the larger cavity 18.

[0053] The entire detection component includes a driven piston 19, a sensing shaft 20, and a displacement detection device 22, wherein the driven piston 19 forms a seal with the cavity 16. The sensing shaft 20 is made of a transparent material, with uniform indentations on it and painted with black pigment; Figure 6As shown, in the displacement detection device 22, a spotlight is installed on one side of the hole for the sensing shaft 20 to pass through, and a light sensor is installed on the other side through a small slit. The light sensor detects the movement distance of the driven piston 19 by counting the number of dark lights.

[0054] Based on the above detection method, after calibration, it can only detect the angle of the steering wheel rotating in the same direction. When the steering wheel rotates back and forth within a small range, the driven piston 19 will move back and forth within a small range, resulting in inaccurate detection. Therefore, a set of gears and Hall chips are installed at the input end of the cylindrical cam 12 to detect the rotation direction of the input shaft. Its installation position is shown in the attached figure. Figure 2 As shown, the driving gear 14 is fixed to the input shaft of the cylindrical cam 12 to ensure that there is no relative movement between the two, and the driven gear 15 is installed in a groove designed on the outside of the hydraulic cylinder body 3. In order to facilitate the Hall chip placed in the small space below the driven gear 15 to detect the rotation direction, a circular permanent magnet is glued to the rear end of the driven gear.

[0055] Based on the above mechanical structure, a corresponding detection algorithm was designed. When the detection system is calibrated, it is defined that when the wheel is parallel to the vehicle body heading angle, all counters are 0, and clockwise steering is positive. The counter is a static variable opened by the internal ECU of the displacement detection device 22 to count the number of times the photosensitive sensor detects a dark grid. When the driver turns the steering wheel clockwise, the direction of the steering wheel rotation will be detected by the Hall chip and marked as positive, and the counter will accumulate; when the driver turns the steering wheel counterclockwise, the counter will decrease. The internal ECU will read the counter value at all times and then calculate the steering wheel angle based on the mechanical structure.

[0056] When the electronic unit of the wire-controlled chassis system fails and loses control, the electronic control ECU determines that the device needs to start the emergency operation mode. At this time, the safety device starts to work. The main components of the safety device, such as the attached Figure 2 As shown, it includes a pin spring 1, a fastening nut 2, a hydraulic cylinder 3, a connecting shaft 10, a spring 11, an electromagnet 23, and a pin 24. The fastening nut 2 and the hydraulic cylinder 3 are threadedly connected, the pin 24 is in a hole in the fastening nut 2 that can slide left and right, and the pin spring 11 is located behind the pin 24 to support the pin 24.

[0057] The safety device needs to establish a mechanical connection between the steering wheel and the column, so the relative movement between the connecting shaft 10 and the cylindrical cam 12 is only relative sliding and cannot rotate. Figure 3 At this time, the electromagnet 23 is powered off and has no attraction, the pin spring 11 is slightly compressed, and the left end of the pin 24 extends into the ring groove at the lower end of the connecting shaft 10. Figure 2When the electronic control unit misjudges the vehicle's driving state or encounters a fatal error, requiring emergency mode, the ECU energizes electromagnet 23. Pin 24, under the electromagnetic force from its left end, moves leftward, further compressing pin spring 11. Once pin 24 is fully removed from the annular groove within connecting shaft 10, spring 11 forces connecting shaft 10 downward, establishing a mechanical connection with the lower transmission mechanism.

[0058] The above description is only part of the specific implementation methods of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person familiar with the art within the technical scope disclosed in the present invention should be covered by the protection scope of the present invention.

Claims

1. A steering wheel angle detection device with a redundant safety device, characterized in that: include: Hydraulic cylinder (3), driven fork (8), limiting sliding device (9), cylindrical cam (12); The hydraulic cylinder body (3) is provided with two cavities, namely a large cavity (18) and a detection cavity (16), and the large cavity (18) and the detection cavity (16) are connected via a flow channel (17); The cylindrical cam (12) is arranged in the large cavity (18); the upper end of the cylindrical cam (12) is an input shaft, The input shaft is rotatably and sealedly connected to the hydraulic cylinder body (3); A connecting shaft (10) is provided inside the cylindrical cam (12), and the connecting shaft (10) and the cylindrical cam (12) cannot rotate relative to each other; An unlocking assembly is mounted on the hydraulic cylinder body (3), and the connecting shaft (10) cooperates with the unlocking assembly. When the unlocking assembly is in an unlocked state, the connecting shaft (10) can generate relative motion with the cylindrical cam (12) in a vertical direction. When the unlocking assembly is in a locked state, the connecting shaft (10) cannot generate relative motion with the cylindrical cam (12). The upper end of the driven fork (8) is a fork tip, the lower end of the driven fork (8) is a fork handle, and the fork tip is connected to the cylindrical cam (12) through the position-limiting sliding device (9); The inner wall of the large cavity (18) is provided with a sliding groove along the axial direction of the cylindrical cam (12), one end of the limiting sliding device (9) is embedded in the sliding groove, and the other end of the limiting sliding device (9) is equipped with a rolling bearing, and the rolling bearing is installed in the profile of the cylindrical cam (12); The fork handle of the driven fork (8) is fixedly connected to the active piston (6); A slave piston (19) is provided in the detection chamber (16), and a sensing detection shaft (20) is connected to the slave piston (19); A displacement detection device (22) is provided on the hydraulic cylinder body (3); the sensing detection shaft (20) passes through the displacement detection device (22).

2. The steering wheel angle detection device with a redundant safety device according to claim 1, characterized in that: The upper end of the connecting shaft (10) includes a limiting shaft, the cross section of the limiting shaft is non-circular, and the inner wall of the cylindrical cam (12) is also provided with a limiting area with a non-circular cross section. The limiting shaft cooperates with the limiting area so that the connecting shaft (10) and the cylindrical cam (12) cannot rotate relative to each other.

3. The steering wheel angle detection device with a redundant safety device according to claim 1, characterized in that: The unlocking assembly comprises: a fastening nut (2), an electromagnet (23), a pin (24) and a pin spring (1); A spring (11) is provided inside the cylindrical cam (12), the upper end of the spring (11) is connected to the upper wall inside the cylindrical cam (12), and the lower end of the spring (11) is connected to the connecting shaft (10); The fastening nut (2) is located at the lower part of the large cavity (18), the fastening nut (2) is connected to the hydraulic cylinder body (3) by threaded connection, the fastening nut (2) is a hollow structure, and the lower part of the connecting shaft (10) passes through the fastening nut (2); The lower portion of the connecting shaft (10) is provided with an annular groove, the side wall of the fastening nut (2) is provided with a through hole, one end of the pin (24) is inserted into the annular groove at the lower portion of the connecting shaft (10) through the through hole, and the other end of the pin (24) is connected to the electromagnet (23) through the pin spring (1); The electromagnet (23) is fixedly connected to the hydraulic cylinder body (3).

4. The steering wheel angle detection device with a redundant safety device according to claim 1, characterized in that: The upper end of the cylindrical cam (12) is also provided with a driving gear (14) and a driven gear (15); The driving gear (14) is fixedly connected to the input shaft of the cylindrical cam (12), the driven gear (15) is meshed with the driving gear (14), the driven gear (15) is magnetic, and a Hall chip is provided on the hydraulic cylinder body (3), and the Hall chip is located at a position facing the driven gear (15).

5. The steering wheel angle detection device with redundant safety device according to claim 1, characterized in that: The cross-sectional area of the detection cavity (16) is 1 / 4 of the large cavity (18).

6. The steering wheel angle detection device with a redundant safety device according to claim 1, characterized in that: The sensing detection shaft (20) is made of a transparent material, and the surface of the sensing detection shaft (20) is densely and evenly covered with indentations, and the indentations are coated with black pigment; The displacement detection device (22) comprises an annular through hole, a spotlight is mounted on the inner wall of one side of the annular through hole, and a photosensitive sensor is mounted on the other side illuminated by the spotlight; the photosensitive sensor detects the moving distance of the driven piston (19) by counting the number of dark lights.

7. The steering wheel angle detection device with a redundant safety device according to claim 1, characterized in that: A limiting nut (21) is also provided at the lower portion of the detection chamber (16).

8. The steering wheel angle detection device with a redundant safety device according to claim 1, characterized in that: The input shaft is rotatably sealed and connected to the hydraulic cylinder body (3) via a sealed bearing (13). The sealing bearing (13) is located at the upper end of the large cavity (18), the inner ring of the sealing bearing (13) is rotatably sealed and connected to the upper end of the cylindrical cam (12), and the outer ring of the sealing bearing (13) is fixedly connected to the hydraulic cylinder body (3); A bearing (4) is provided at the lower end of the large cavity (18), the bearing (4) is fixedly connected to the hydraulic cylinder body (3), and the lower part of the connecting shaft (10) passes through the bearing (4) and extends out of the cylindrical cam (12).

9. The steering wheel angle detection device with a redundant safety device according to claim 1, characterized in that: The fork handle of the driven fork (8) and the active piston (6) are provided with a plurality of mounting holes. The driven fork (8) and the active piston (6) are fixedly connected by inserting a plurality of mounting pins (7) into the mounting holes on the active fork (8) and the active piston (6). A sealing ring (5) is also installed on the outside of the active piston (6).

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