Low-cost torque and angle measurement sensor for EPS and measurement method

Abstract

The invention relates to the technical field of steering systems, in particular to a low-cost torque and angle measurement sensor for an EPS and a measurement method. According to the low-cost torque and angle measurement sensor for the EPS, the bottom of an input shaft is connected with an output shaft, and a sensor is arranged between the input shaft and the output shaft; the main gear comprises an upper main gear and a lower main gear; the small auxiliary gear comprises an upper small auxiliary gear and a lower small auxiliary gear, the upper main gear is connected with the input shaft, the lower main gear is connected with the output shaft, one side of the upper main gear and one side of the lower main gear are connected with the upper small auxiliary gear and the lower small auxiliary gear in a meshed mode respectively, and a PCBA circuit board is arranged between the upper small auxiliary gear and the lower small auxiliary gear. The PCBA circuit board is connected with the digital communication interface through a communication protocol. Compared with the prior art, the torque signal and the angle signal are simultaneously measured by using one sensor, so that the number of parts is reduced, the cost is reduced, and the reliability is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of steering systems, and in particular to a low-cost torque and angle measurement sensor and a measurement method for EPS. Background Art

[0002] In the current automotive EPS market, the mainstream torque and angle sensors are the following two:

[0003] Solution A: Torque and angle are measured separately, that is, the torque part and the angle part are measured by two sensors respectively. EPS provides the steering wheel torque signal to the whole vehicle through communication. A separate angle sensor is added to the shaft connected to the steering wheel outside the EPS to provide the absolute steering wheel angle signal to the whole vehicle.

[0004] Solution B: Combined measurement of torque and angle, that is, the torque part and the angle part are measured by an integrated sensor. EPS can provide the torque signal and absolute angle signal of the steering wheel at the same time.

[0005] However, there are two types of mainstream solutions B on the market: one is to realize torque and angle using different structures and principles. This solution has many parts, complex structure, complex assembly process and high cost; the other is an integrated measurement using an inductive solution. Although this solution has fewer parts, due to its special inductive type, it has extremely high requirements on PCB processing and sensor assembly accuracy. At the same time, special chips need to be customized. After powering off and then on again, it needs to be rotated a certain angle to complete the learning of the absolute angle. Although the cost of this solution is lower than the former, it still does not have a competitive advantage. Summary of the invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a low-cost torque and angle measurement sensor and measurement method for EPS, using one sensor to simultaneously measure the torque signal and the angle signal, reducing the number of parts, which not only reduces the cost but also greatly increases the reliability.

[0007] To achieve the above purpose, a low-cost torque and angle measurement sensor for EPS is designed, comprising an input shaft, a sensor, and an output shaft, characterized in that: the bottom of the input shaft is connected to the output shaft, and a sensor is provided between the input shaft and the output shaft; the sensor comprises an upper cover, a main gear, a sensor housing, a small sub-gear, a PCBA circuit board, and a digital communication interface, the main gear comprises an upper main gear and a lower main gear; the small sub-gear comprises an upper small sub-gear and a lower small sub-gear, the upper main gear is connected to the input shaft, the lower main gear is connected to the output shaft, one side of the upper main gear and the lower main gear are respectively meshed and connected to the upper small sub-gear and the lower small sub-gear, a PCBA circuit board is provided between the upper small sub-gear and the lower small sub-gear, and the PCBA circuit board is connected to the digital communication interface through a communication protocol.

[0008] The input shaft and the output shaft are connected via a torsion bar, and the torsion bar passes through the sensor.

[0009] The upper main gear, the lower main gear, the upper small sub-gear, the lower small sub-gear, the PCBA circuit board, and the digital communication interface are located inside the sensor housing, and the top of the sensor housing is connected to the upper cover; one end of the digital communication interface is connected to the PCBA circuit board, and the other end of the digital communication interface is connected to an external device.

[0010] The upper small gear and the lower small gear are respectively provided with magnets, and the magnets include a pair of magnetic poles.

[0011] The front and back sides of the PCBA circuit board are respectively connected to universal angle chips, and the two angle chips correspond to the magnets on the upper small sub-gear and the lower small sub-gear respectively.

[0012] A measurement method for a low-cost torque and angle measurement sensor for EPS, the specific measurement method is as follows:

[0013] (1) When the car battery KL30 is powered on again, it is considered that the steering wheel has no force applied, that is, the torque is 0. At this time, the cursor algorithm can be used to calculate the current steering wheel angle without recalibration;

[0014] (2) When the car's small battery KL30 is continuously powered, the current absolute steering wheel angle is calculated in real time through the following algorithm of the upper small pinion.

[0015] The specific process of the cursor algorithm is as follows:

[0016] (11) When the upper and lower main gears and the upper and lower pinion gears mesh and rotate, the angular relationship between the gears is: the abscissa is the absolute rotation angle of the main gear, and the ordinate is the relative rotation angle of the pinion gear;

[0017] (12) When the upper and lower main gears are within a certain angle range, the relative angle of the upper and lower small sub-gears is a unique value, that is, the absolute angle of the two main gears is matched inversely by the relative angle of the two small sub-gears. The calculation method is: Among them, m is the number of teeth of the upper small gear, n is the number of teeth of the lower small gear, X is the number of teeth of the main gear, and gcd(m,n) represents the greatest common divisor of m and n.

[0018] Described m=26, n=28, X=65, MX=2016°, that is, the absolute angle of the steering wheel is measured within the range of ±1008°.

[0019] The specific process of the following algorithm is as follows:

[0020] (21) When the car battery KL30 is continuously powered, the system calculates the absolute steering wheel angle through the cursor algorithm and records it as Angle X. When the angle of the small secondary gear rotation changes to ΔAngle m, the new absolute steering wheel angle Angle X is n for Among them, X is the number of teeth on the main gear, and m is the number of teeth on the upper small auxiliary gear;

[0021] (22) At the same time, when the relative angle of the pinion gear changes from 360° to 0°, the corresponding relative angle in the next 360° cycle is added with 360° as the converted angle;

[0022] (23) When the relative angle of the pinion gear changes from 0° to 360°, the corresponding relative angle in the next 360° cycle is subtracted by 360° as the converted angle;

[0023] (24) The correspondence between the converted upper pinion gear and the main gear X: the horizontal axis is the angle of the main gear X;

[0024] (25) According to the above-mentioned following algorithm, the absolute angle X1 of the upper main gear fixed to the input shaft is calculated by the upper pinion gear, and the absolute angle X2 of the lower main gear fixed to the output shaft is calculated by the lower pinion gear;

[0025] (26) The difference between the two, ΔX = X1-X2, is the relative rotation angle between the input shaft and the output shaft;

[0026] (27)The torque is obtained as T = (X1-X2)*k; where k is the stiffness coefficient of the torsion bar.

[0027] The ΔAngle m is a positive value in a positive direction and a negative value in a negative direction.

[0028] Compared with the prior art, the present invention provides a low-cost torque and angle measurement sensor and measurement method for EPS, which uses one sensor to simultaneously measure torque signals and angle signals, reducing the number of parts, which not only reduces costs but also greatly increases reliability; and the absolute angle can be obtained without any operation after power failure and power on again. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the hardware structure of the present invention.

[0030] Figure 2 It is an exploded diagram of the hardware structure of the present invention.

[0031] Figure 3 It is an exploded diagram of the sensor structure in the present invention.

[0032] Figure 4 This is the cursor algorithm curve chart.

[0033] Figure 5 Diagram of the meshing relationship between the main gear and the pinion gear.

[0034] Figure 6 This is the corresponding relationship diagram between the small secondary gear and the main gear after conversion. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the accompanying drawings.

[0036] like Figures 1 to 3 As shown, the bottom of the input shaft 1 is connected to the output shaft 3, and a sensor 2 is provided between the input shaft 1 and the output shaft 3; the sensor 2 includes an upper cover, a main gear, a sensor housing, a small sub-gear, a PCBA circuit board, and a digital communication interface. The main gear includes an upper main gear 2.2 and a lower main gear 2.8; the small sub-gear includes an upper small sub-gear 2.4 and a lower small sub-gear 2.6. The upper main gear 2.2 is connected to the input shaft 1, and the lower main gear 2.8 is connected to the output shaft 3. One side of the upper main gear 2.2 and the lower main gear 2.8 are respectively meshed and connected to the upper small sub-gear 2.4 and the lower small sub-gear 2.6. A PCBA circuit board 2.5 is provided between the upper small sub-gear 2.4 and the lower small sub-gear 2.6, and the PCBA circuit board 2.5 is connected to the digital communication interface 2.7 through a communication protocol.

[0037] The input shaft 1 and the output shaft 3 are connected via a torsion bar 4 , and the torsion bar 4 passes through the sensor 2 .

[0038] The upper main gear 2.2, the lower main gear 2.8, the upper small sub-gear 2.4, the lower small sub-gear 2.6, the PCBA circuit board 2.5, and the digital communication interface 2.7 are located inside the sensor housing 2.3, and the top of the sensor housing 2.3 is connected to the upper cover 2.1; one end of the digital communication interface 2.7 is connected to the PCBA circuit board 2.5, and the other end of the digital communication interface 2.7 is connected to an external device.

[0039] The upper small pinion gear 2.4 and the lower small pinion gear 2.6 are respectively provided with magnets, each of which includes a pair of magnetic poles.

[0040] The front and back sides of the PCBA circuit board 2.5 are respectively connected to universal angle chips, and the two angle chips correspond to the magnets on the upper small sub-gear 2.4 and the lower small sub-gear 2.6 respectively.

[0041] The upper main gear 2.2 and the lower main gear 2.8 are fixed on the input shaft 1 and the output shaft 2 respectively, and the upper main gear 2.2 and the lower main gear 2.8 can rotate with the shaft.

[0042] At the same time, the input shaft 1 and the output shaft 2 are connected by a torsion bar 4. When the steering wheel is turned, the torsion bar 4 undergoes elastic deformation, and the input shaft 1 and the output shaft 3 rotate relative to each other.

[0043] The upper main gear 2.2 and the lower main gear 2.8 are meshed with the upper small sub-gear 2.4 and the lower small sub-gear 2.6 respectively, and the small sub-gears are driven to rotate when the main gears rotate. Both small sub-gears have magnets, and the magnets include a pair of magnetic poles.

[0044] There are two universal angle chips on both sides of the PCBA circuit board 2.5, which can measure the magnetic field angle of 0 to 360 degrees. The two angle chips correspond to the two small sub-gears respectively, and can measure the current angle of the small sub-gear in real time, and transmit it to the outside through the digital communication interface 2.7 using a certain communication protocol after digital encoding.

[0045] A measurement method of a low-cost torque and angle measurement sensor for EPS is shown in Table 1. The specific measurement method is as follows:

[0046] (1) When the car battery KL30 is powered on again, it is considered that the steering wheel has no force applied, that is, the torque is 0. At this time, the cursor algorithm can be used to calculate the current steering wheel angle without recalibration;

[0047] (2) When the car's small battery KL30 is continuously powered, the current absolute steering wheel angle is calculated in real time through the following algorithm of the upper small pinion.

[0048] Table 1

[0049]

[0050] like Figure 4 , Figure 5 As shown, the specific process of the cursor algorithm is as follows:

[0051] (11) When the upper and lower main gears and the upper and lower pinion gears mesh and rotate, the angular relationship between the gears is: the abscissa is the absolute rotation angle of the main gear, and the ordinate is the relative rotation angle of the pinion gear;

[0052] (12) When the upper and lower main gears are within a certain angle range, the relative angle of the upper and lower small sub-gears is a unique value, that is, the absolute angle of the two main gears is matched inversely by the relative angle of the two small sub-gears. The calculation method is: Among them, m is the number of teeth of the upper small gear, n is the number of teeth of the lower small gear, X is the number of teeth of the main gear, and gcd(m,n) represents the greatest common divisor of m and n.

[0053] m=26, n=28, X=65, MX=2016°, that is, the absolute angle of the steering wheel is measured within the range of ±1008°.

[0054] like Figure 6 As shown, the specific process of the following algorithm is as follows:

[0055] (21) When the car battery KL30 is continuously powered, the system calculates the absolute steering wheel angle through the cursor algorithm and records it as Angle X. When the angle of the small secondary gear rotation changes to ΔAngle m, the new absolute steering wheel angle Angle X is n for Among them, X is the number of teeth on the main gear, and m is the number of teeth on the upper small auxiliary gear;

[0056] (22) At the same time, when the relative angle of the pinion gear changes from 360° to 0°, the corresponding relative angle in the next 360° cycle is added with 360° as the converted angle;

[0057] (23) When the relative angle of the pinion gear changes from 0° to 360°, the corresponding relative angle in the next 360° cycle is subtracted by 360° as the converted angle;

[0058] (24) The correspondence between the converted upper pinion gear and the main gear X: the horizontal axis is the angle of the main gear X;

[0059] (25) According to the above-mentioned following algorithm, the absolute angle X1 of the upper main gear fixed to the input shaft is calculated by the upper pinion gear, and the absolute angle X2 of the lower main gear fixed to the output shaft is calculated by the lower pinion gear;

[0060] (26) The difference between the two, ΔX = X1-X2, is the relative rotation angle between the input shaft and the output shaft;

[0061] (27)The torque is obtained as T = (X1-X2)*k; where k is the stiffness coefficient of the torsion bar.

[0062] ΔAngle m is positive in the positive direction and negative in the negative direction.

Claims

1. A low-cost torque and angle measurement sensor for EPS, comprising an input shaft, a sensor, and an output shaft, characterized in that: The bottom of the input shaft (1) is connected to the output shaft (3), and a sensor (2) is provided between the input shaft (1) and the output shaft (3); the sensor (2) comprises an upper cover, a main gear, a sensor housing, a small sub-gear, a PCBA circuit board, and a digital communication interface; the main gear comprises an upper main gear (2.2) and a lower main gear (2.8); the small sub-gear comprises an upper small sub-gear (2.4) and a lower small sub-gear (2.6); the upper main gear (2.2) is connected to the input shaft (1), the lower main gear (2.8) is connected to the output shaft (3), one side of the upper main gear (2.2) and the lower main gear (2.8) are respectively meshed and connected to the upper small sub-gear (2.4) and the lower small sub-gear (2.6); a PCBA circuit board (2.5) is provided between the upper small sub-gear (2.4) and the lower small sub-gear (2.6), and the PCBA circuit board (2.5) is connected to the digital communication interface (2.7) through a communication protocol.

2. A low-cost torque and angle measurement sensor and measurement method for EPS according to claim 1, characterized in that: The input shaft (1) and the output shaft (3) are connected via a torsion bar (4), and the torsion bar (4) passes through the sensor (2).

3. A low-cost torque and angle measurement sensor and measurement method for EPS according to claim 1, characterized in that: The upper main gear (2.2), the lower main gear (2.8), the upper small sub-gear (2.4), the lower small sub-gear (2.6), the PCBA circuit board (2.5), and the digital communication interface (2.7) are located inside the sensor housing (2.3), and the top of the sensor housing (2.3) is connected to the upper cover (2.1); one end of the digital communication interface (2.7) is connected to the PCBA circuit board (2.5), and the other end of the digital communication interface (2.7) is connected to an external device.

4. A low-cost torque and angle measurement sensor and measurement method for EPS according to claim 1 or 3, characterized in that: The upper small sub-gear (2.4) and the lower small sub-gear (2.6) are respectively provided with magnets, each of which includes a pair of magnetic poles.

5. A low-cost torque and angle measurement sensor and measurement method for EPS according to claim 1 or 3, characterized in that: The front and back sides of the PCBA circuit board (2.5) are respectively connected to universal angle chips, and the two angle chips correspond to magnets on the upper small sub-gear (2.4) and the lower small sub-gear (2.6).

6. A method for measuring low-cost torque and angle measurement sensors for EPS, characterized in that: The specific measurement method is as follows: (1) When the car battery KL30 is powered on again, it is considered that the steering wheel has no force applied, that is, the torque is 0. At this time, the cursor algorithm can be used to calculate the current steering wheel angle without recalibration; (2) When the car's small battery KL30 is continuously powered, the current absolute steering wheel angle is calculated in real time through the following algorithm of the upper small pinion.

7. The method for measuring a low-cost torque and angle measurement sensor for EPS according to claim 6, characterized in that: The specific process of the cursor algorithm is as follows: (11) When the upper and lower main gears and the upper and lower pinion gears mesh and rotate, the angular relationship between the gears is: the abscissa is the absolute rotation angle of the main gear, and the ordinate is the relative rotation angle of the pinion gear; (12) When the upper and lower main gears are within a certain angle range, the relative angle of the upper and lower small sub-gears is a unique value, that is, the absolute angle of the two main gears is matched inversely by the relative angle of the two small sub-gears. The calculation method is: Among them, m is the number of teeth of the upper small gear, n is the number of teeth of the lower small gear, X is the number of teeth of the main gear, and gcd(m,n) represents the greatest common divisor of m and n.

8. The method for measuring a low-cost torque and angle measurement sensor for EPS according to claim 7, characterized in that: The m=26, n=28, X=65, MX=2016°, that is, the steering wheel is ±1008° The absolute angle is measured within the range of 9. The method for measuring a low-cost torque and angle measurement sensor for EPS according to claim 6, characterized in that: The specific process of the following algorithm is as follows: (21) When the car battery KL30 is continuously powered, the system calculates the absolute steering wheel angle through the cursor algorithm and records it as Angle X. When the angle of the small secondary gear rotation changes to ΔAngle m, the new absolute steering wheel angle Angle X is n for Among them, X is the number of teeth on the main gear, and m is the number of teeth on the upper small auxiliary gear; (22) At the same time, when the relative angle of the pinion gear changes from 360° to 0°, the corresponding relative angle in the next 360° cycle is added with 360° as the converted angle; (23) When the relative angle of the pinion gear changes from 0° to 360°, the corresponding relative angle in the next 360° cycle is subtracted by 360° as the converted angle; (24) The correspondence between the converted upper pinion gear and the main gear X: the horizontal axis is the angle of the main gear X; (25) According to the above-mentioned following algorithm, the absolute angle X1 of the upper main gear fixed to the input shaft is calculated by the upper pinion gear, and the absolute angle X2 of the lower main gear fixed to the output shaft is calculated by the lower pinion gear; (26) The difference between the two, ΔX = X1-X2, is the relative rotation angle between the input shaft and the output shaft; (27)The torque is obtained as T = (X1-X2)*k; where k is the stiffness coefficient of the torsion bar.

10. The method for measuring a low-cost torque and angle measurement sensor for EPS according to claim 9, characterized in that: The ΔAngle m is a positive value in a positive direction and a negative value in a negative direction.

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