An integrated sensor structure combining steering wheel torque and angle detection functions

Abstract

The present invention relates to an integrated sensor structure combining steering wheel torque and angle detection functions, comprising a torque detection unit and an angle detection unit, wherein the torque detection unit comprises an axially magnetized multi-pole magnetic ring (10), a magnetic flux converging ring (101, 102), an annular bracket (20), a magnetic flux buncher (103, 104) and a magnetic sensitive element (30), and the angle detection unit comprises a driving gear (40), two driven gear assemblies (51, 52) with different numbers of teeth and a magnetic sensitive element (61, 62). The scheme can suppress the mutual interference between two magnetic circuits in the integrated sensor, improve the detection accuracy, and optimize the stability and reliability of the sensor.

Description

Technical Field

[0001] The invention relates to a sensor, in particular to an integrated sensor structure combining steering wheel torque and rotation angle detection functions, belonging to the technical field of sensors. Background Art

[0002] The electric power steering system of a motor vehicle usually requires a torque sensor and a steering angle sensor, which are used for timely detection of steering wheel torque and steering wheel angle position respectively.

[0003] Combining the torque and angle detection functions of two sensors and integrating them into one sensor can reduce the number of components, reduce system space occupation, reduce system costs, make the system's spatial layout more flexible, and further improve system reliability.

[0004] There are two types of integrated sensors for electric power steering systems: contact type and non-contact type.

[0005] BI technologies' SX-4300A is a typical product of contact-type torque angle integrated sensor. The main defect of contact-type sensor is its contact point, which has the problems of contact noise and wear, affecting the stability, reliability and service life of the product.

[0006] After preliminary search, CN 104870958 B discloses a non-contact torque angle integrated sensor, whose torque and angle signal detection are both based on the principle of magnetic sensitive sensors, and whose rotating transmission element with permanent magnet is arranged between boundary elements in the axial direction. Its rotating transmission element is the driven gear of the angle detection unit, and its boundary element is the magnetic flux convergence ring of the torque detection unit. Since the radial gap between the magnetic ring of the driven gear and the magnetic flux convergence ring approaches zero, the magnetic circuit of the angle unit will significantly interfere with the torque magnetic circuit, affecting the angular resolution of the torque sensor.

[0007] The principle of magnetic sensor is the preferred type of torque sensor principle and angle sensor. However, the sensor structure that integrates the two detection functions into one must have mutual interference between the torque magnetic circuit and the angle magnetic circuit. Therefore, a new solution that effectively suppresses the interference of the magnetic circuit of the angle unit on the torque magnetic circuit is an urgent need for non-contact torque angle integrated sensors. Summary of the invention

[0008] The present invention aims at the problems existing in the prior art and provides an integrated sensor structure that combines the steering wheel torque and angle detection functions. The technical solution improves the spatial structure of the integrated sensor, optimizes the structural design, increases the radial gap between the torque magnetic circuit and the angle magnetic circuit, and suppresses the mutual interference between the two sensor magnetic circuits. This makes the torque signal of the integrated sensor have smaller detection error and higher detection accuracy, thereby significantly improving the stability and reliability of the sensor.

[0009] In order to achieve the above-mentioned purpose, the technical solution of the present invention is as follows: an integrated sensor structure that combines steering wheel torque and angle detection functions, including a torque detection unit and an angle detection unit, the torque detection unit includes an axially magnetized multi-pole magnetic ring, a flux converging ring, an annular bracket, a flux buncher and a magnetic sensitive element, the angle detection unit includes a driving gear, two driven gear assemblies with different numbers of teeth and a magnetic sensitive element, the axial position of the driving gear of the angle detection unit is set below the flux converging ring, and there is no meshing intersection of the master / slave gears between the flux converging rings of the torque detection unit.

[0010] At present, the electric power steering system of motor vehicles generally uses two sensors with single detection functions, which are used to detect steering wheel torque and steering wheel angle respectively. The torque sensor is used to sense the torque information applied by the driver to the steering wheel, which is used for the control of the power motor. The torque angle range corresponding to the torque is usually around ±5°; the angle sensor is used to sense the real-time position of the steering wheel, which is used for the automatic return control of the steering wheel. The angle sensor is usually required to identify the real-time position of the steering wheel for more than 5 positive and negative rotations (±1800°).

[0011] In view of the many advantages of magnetic sensing technology, such as simple structure, low cost, and suitability for harsh environments, sensors with a single detection function all adopt the magnetic sensing principle. The integrated sensor combines two magnetic sensors with detection functions in a small space. The magnetic field of the angle sensor will interfere with the torque magnetic circuit that requires high resolution. Therefore, suppressing the magnetic field interference of the angle sensor is the key to ensuring the quality of the integrated sensor.

[0012] There are three options for suppressing the magnetic field interference of the angle sensor, and their feasibility is as follows: 1. Select low magnetic energy product and small magnet size to reduce the magnetic field strength of the angle sensor. This is a solution adopted by the known technology. Since the magnetic field strength of the angle sensor cannot be reduced infinitely, there is no possibility of further improvement. 2. Set a magnetic shielding component between the magnetic flux convergence plate of the torque magnetic circuit and the corner magnet. For details, see (51) in CN 104870958 B. However, experiments show that the shielding component added between the two magnetic circuits actually enhances the interference of the magnetic field of the angle sensor on the torque magnetic circuit. Because the material of the magnetic shielding component must be a magnetic conductor, when the magnetic field comes from a single magnetic source, the shielding component acts as a low magnetic resistance channel for magnetic lines of force, which can significantly reduce the divergence of magnetic lines of force outside the shielding component; when the magnetic field comes from different magnetic sources, the shielding component becomes a low magnetic resistance channel connecting different magnetic circuits, which will increase the mutual interference between the magnetic circuits. Therefore, the solution of setting a magnetic shielding component between the two magnetic circuits is not feasible. 3. Increase the radial gap between the torque magnetic circuit and the corner magnet. Since the magnetic field strength decays exponentially with distance, increasing the radial gap is the only improvement option that can suppress the magnetic field interference of the angle sensor.

[0013] Increasing the radial gap between the torque magnetic circuit and the corner magnet means increasing the radial gap between the magnetic ring of the flux converging ring and the driven gear assembly. Since the driving gear and the flux converging ring are coaxially mounted on the annular bracket, increasing the gap requires increasing the tooth top diameter of the driving gear, and the feasibility of increasing the tooth top diameter of the driving gear depends on the axial position with the main gear. With the position of the coaxially mounted flux converging ring as a reference, there are three options for the axial position of the main gear: 1. Set the axial position of the main gear above the upper flux converging ring 101. The axial position of the driven gear that is meshed with the main gear is also required to be set above the flux converging ring 101. The magnet working surface of the driven gear has two orientations: upward and downward. When facing downward, the shaft seat of the driven gear must be set on the upper housing of the sensor, and the shaft seat must adopt a complex structure that supports the gravity of the driven gear. When facing upward, the magnetic sensitive element (61, 62) and the PCB must be set above the magnet working surface, that is, above the magnetic flux converging ring position 101, and the magnetic sensitive element (30) of the torque magnetic unit is set between the magnetic flux converging ring positions 101 and 102. The axial positions of the magnetic sensitive elements of the torque unit and the angle unit are different. Two PCBs must be used for installation respectively, which not only increases the manufacturing difficulty but also reduces the reliability of the sensor. 2. The axial position of the main gear is set between the magnetic flux converging rings. The magnetic flux converging rings are also the installation positions of the magnetic flux buncher (103, 104) and the magnetic sensitive element (30). When the tooth top diameter of the driving gear is increased, in order to avoid interference with the torque magnetic circuit element, the radial positions of the magnetic flux buncher and the magnetic sensitive element must be increased at the same time, so that the radial size of the sensor assembly increases synchronously. Due to the limitation of user installation space, it is not feasible. 3. The axial position of the main gear is set below the lower magnetic flux converging ring 102. This position does not have the space limitation and disadvantages of the above two positions.

[0014] It can be seen that the axial position of the driving gear of the rotation angle detection unit is set below the magnetic flux converging ring, which is a necessary prerequisite for implementing the technical solution of suppressing the magnetic field interference of the rotation angle sensor.

[0015] As an improvement of the present invention, the driven gear assembly (51, 52) of the rotation angle detection unit comprises a driven gear (513, 523) and a magnetic ring (512, 522); the axial position of the driven gear (513, 523) is arranged below the magnetic flux converging ring (102) and meshes with the driving gear for rotation.

[0016] As an improvement of the present invention, the module of the angle detection unit gear is set to 0.7, and the transmission ratio of the driving gear to the driven gear (transmission ratio = number of teeth of the driving gear / number of teeth of the driven gear) is set to ≥3.33, which can significantly increase the outer diameter of the driving gear, which is a necessary condition for increasing the radial gap between the magnetic flux converging ring and the annular magnet of the driven gear assembly. The module value is 0.7, and the transmission ratio value is ≥3.33, which is suitable for the conventional requirements of the electric power steering system for the steering wheel angle range, and the angle range can reach more than ±5 turns (±1800°).

[0017] As an improvement of the present invention, the radial position of the annular magnet of the driven gear assembly of the angle detection unit is outside the magnetic flux convergence ring, and the minimum radial gap between the magnetic flux convergence ring and the annular magnet of the driven gear assembly is increased from 0 mm to more than 2.5 mm. In order to suppress the mutual interference between the torque magnetic circuit and the corner magnetic circuit, the known magnetic-sensitive torque angle integrated sensor sets a magnetic field shielding component between the magnetic flux convergence plate of the torque magnetic circuit and the corner magnet, in an attempt to suppress the mutual interference between the torque magnetic circuit and the corner magnetic circuit. Experiments have shown that the shielding component added between the two magnetic circuits not only has no shielding effect, but will increase the mutual interference between the two magnetic circuits. The smaller the radial gap between the torque magnetic circuit and the corner magnet, the greater the interference. The only feasible way to suppress the interference between the magnetic circuits is to increase the radial gap between the torque magnetic circuit and the corner magnetic circuit. Through optimized structural design, this solution increases the minimum radial gap between the two magnetic circuits from 0 mm to more than 2.5 mm, which can reduce the interference of the magnetic field of the annular magnet of the driven gear assembly on the torque magnetic circuit by more than 70%, and increase the angular resolution of the torque sensor by more than 2 times.

[0018] As an improvement of the present invention, the annular magnetic ring of the driven gear assembly has a pair of radially magnetized magnetic poles. Compared with multiple pairs of magnetic poles, the angular rotation of a pair of magnetic poles causes the largest change in magnetic flux and the strongest signal, which is conducive to optimizing the signal-to-noise ratio.

[0019] As an improvement of the present invention, it is clarified that the magnetic sensitive element is located above the magnetic ring of the angle detection unit, and the sensitive center of the magnetic sensitive element coincides with the center of the magnetic ring. In view of the fact that the magnetic sensitive elements for detecting angular displacement are manufactured by different manufacturers, their sensitive center positions may coincide with or not coincide with the geometric center, and the coincidence of the sensitive center with the center of the magnetic ring is an important prerequisite for ensuring the performance of the sensor.

[0020] Compared with the prior art, the technical effects of the present invention are as follows: 1) This solution can suppress the mutual interference between the two magnetic circuits in the integrated sensor, so that the torque angle resolution is improved from 0.02° to better than 0.006°, thereby improving the torque detection accuracy of the sensor; 2) This technical solution changes the axial position of the active gear from between the magnetic flux converging rings to below the magnetic flux converging rings, and the outer diameter value of the active gear is not restricted by the interference with the magnetic flux buncher and magnetic sensitive element of the torque magnetic circuit, which is an innovative measure to implement magnetic interference suppression in a limited space; 3) This solution optimizes the structural design The minimum radial gap between the two magnetic circuits is increased from 0mm to more than 2.5mm. While improving the torque angle resolution, it also reduces the fluctuation of the torque angle signal caused by interference (because the magnetic field direction of the radial magnets of the two driven gears with different numbers of teeth changes with the rotation angle, the interference amplitude of the rotation angle magnetic field will change dynamically with the rotation angle), optimizing the stability of the sensor torque signal; 4) The annular magnetic ring of the driven gear assembly described in this scheme has a pair of radially magnetized magnetic poles, and the magnetic flux change caused by its angular rotation is the largest, the signal is the strongest, and it is conducive to the optimization of the signal-to-noise ratio. 5) The scheme is designed so that the sensitive center of the magnetic sensitive element coincides with the center of the magnetic ring, further ensuring the performance of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is an exploded view of the integrated sensor structure that combines the steering wheel torque and angle detection functions;

[0022] Figure 2 This is the assembly status of the integrated sensor. Figure 1 ;

[0023] Figure 3 This is the assembly status of the integrated sensor. Figure 2 ;

[0024] Figure 4 This is an example 1 of the installation position of the magnetic sensitive element of the driven gear assembly;

[0025] Figure 5 This is Example 2 of the installation position of the magnetic sensitive element of the driven gear assembly. DETAILED DESCRIPTION

[0026] In order to deepen the understanding of the present invention, the present embodiment is described in detail below with reference to the accompanying drawings.

[0027] Example 1: See Figure 1 , an integrated sensor structure that combines steering wheel torque and angle detection functions, Figure 1It is an exploded view of an integrated sensor structure that combines steering wheel torque and angle detection functions, including a torque detection unit and an angle detection unit. The torque detection unit includes an axially magnetized multi-pole magnetic ring 10, flux converging rings 101 and 102, an annular bracket 20, flux bunchers 103 and 104, and a magnetic sensitive element 30. The angle detection unit includes a driving gear 40, two driven gear assemblies 51 and 52 with different numbers of teeth, and magnetic sensitive elements 61 and 62. The axial hole of the multi-pole magnetic ring 10 of the torque detection unit is installed on the input shaft of the steering column of the steering wheel, and the flux bunchers 103 and 104 are arranged between the flux converging rings 101 and 102. The magnetic sensitive element 30 is arranged in the air gap between the flux bunchers 103 and 104.

[0028] The axial hole of the annular bracket 20 is installed on the output shaft of the steering column of the steering wheel. The magnetic flux converging ring 102 of the torque detection unit is fixed on the annular bracket 20 by molding. The driving gear 40 is coaxially arranged below the magnetic flux converging ring 102. There is no meshing intersection of the master / slave gears between the magnetic flux converging rings of the torque detection unit. In this technical solution, the axial position of the driving gear is changed from between the magnetic flux converging rings to below the magnetic flux converging rings, because the magnetic circuit channel of the torque detection unit is between the magnetic flux converging rings, and the magnetic flux buncher and magnetic sensitive element of the torque detection unit need to be arranged therebetween. When the driving gear is arranged between the magnetic flux converging rings, the master / slave gears must mesh and intersect between the magnetic flux converging rings. In order to avoid interference between the driving gear and the magnetic flux buncher and magnetic sensitive element of the torque magnetic circuit, the driving gear can only have a smaller outer diameter, so that the radial gap between the magnetic flux converging ring of the torque magnetic circuit and the driven gear magnet is ≈0, resulting in significant interference of the angle magnetic circuit with the torque magnetic circuit. By changing the axial position of the driving gear from between the flux converging rings to below the flux converging rings, the outer diameter of the driving gear is not restricted to interfere with the flux concentrator and magnetic sensitive element of the torque magnetic circuit.

[0029] The driven gear assemblies 51 and 52 respectively include driven gears 513 and 523 and magnetic rings 512 and 522. The driven gears 513 and 523 and the magnetic rings 512 and 522 are combined into one body of the driven gear assemblies 51 and 52 by molding.

[0030] Figure 2 This is the assembly status of the integrated sensor. Figure 1 After assembly, the magnetic flux converging ring 101 is installed in the upper slot of the annular bracket 20, and the axial positions of the driven gears 513 and 523 are set below the magnetic flux converging ring 102 and mesh with the driving gear 40 for rotation.

[0031] In this scheme, the module of the angle detection unit gear is set to 0.7, and the transmission ratio of the driving gear to the driven gear (transmission ratio = number of teeth of the driving gear / number of teeth of the driven gear) is set to ≥3.33, which can significantly increase the outer diameter of the driving gear, which is a necessary condition for increasing the radial gap between the magnetic flux convergence ring and the annular magnet of the driven gear assembly. The module value is 0.7, and the transmission ratio value is ≥3.33, which is suitable for the conventional requirements of the electric power steering system for the steering wheel angle range, and the angle range can reach more than ±5 turns (±1800°).

[0032] Figure 3 This is the assembly status of the integrated sensor. Figure 2 The collecting teeth of the flux converging rings 101 and 102 overlap axially, d1 and d2 are radial clearances between the flux converging rings 101 and 102 and the magnetic rings 512 and 522 of the driven gear assemblies 51 and 52, and this solution requires that the design values ​​of d1 and d2 are ≥2.5mm.

[0033] In this scheme, the radial position of the annular magnet of the driven gear assembly of the angle detection unit is outside the magnetic flux convergence ring, and the minimum radial gap between the magnetic flux convergence ring and the annular magnet of the driven gear assembly is increased from 0 mm to more than 2.5 mm. In order to suppress the mutual interference between the torque magnetic circuit and the angle magnetic circuit, the known magnetic sensitive torque angle integrated sensor sets a magnetic field shielding component between the magnetic flux convergence sheet of the torque magnetic circuit and the angle magnet, trying to suppress the mutual interference between the torque magnetic circuit and the angle magnetic circuit. Since the material of the shielding component can only be a magnetic conductor, the shielding component added between the two magnetic circuits not only has no shielding effect, but will increase the mutual interference between the two magnetic circuits. There are three ways to suppress interference between magnetic circuits: 1. Reduce the size of the driven gear magnetic ring of the angle unit. 2. Reduce the magnetic field strength of the driven gear magnetic ring. 3. Increase the radial gap between the torque magnetic circuit and the angle magnetic circuit. The first two methods will cause the signal of the angle unit to drop, affecting the sensitivity and reliability of the angle unit. Only the third method of increasing the radial gap between the torque magnetic circuit and the angular magnetic circuit is the only feasible way to suppress the interference between the magnetic circuits. This solution increases the minimum radial gap between the two magnetic circuits from 0mm to more than 2.5mm through optimized structural design, which can reduce the interference of the magnetic field of the annular magnet of the driven gear assembly on the torque magnetic circuit by more than 70%, and increase the angular resolution of the torque sensor by more than 2 times.

[0034] Figure 4 This is example 1 of the installation position of the magnetic sensitive element of the driven gear assembly. In this example, the sensitive center A of the IC deviates from the geometric center. When designing the layout of the PCB, the sensitive center A of the IC should coincide with the center of the magnetic ring of the driven gear assembly to ensure that the magnetic sensitive element can efficiently collect the angular displacement signal of the magnetic ring.

[0035] Figure 5This is Example 2 of the installation position of the magnetic sensitive element of the driven gear assembly. In this example, the sensitive center A of the IC is the geometric center. When designing the layout of the PCB, the sensitive center A of the IC should be set at the center of the magnetic ring of the driven gear assembly to ensure that the magnetic sensitive element efficiently collects the angular displacement signal of the magnetic ring.

[0036] It should be noted that the above embodiments are not intended to limit the protection scope of the present invention, and equivalent changes or substitutions made on the basis of the above technical solutions all fall within the protection scope of the claims of the present invention.

Claims

1. An integrated sensor structure combining steering wheel torque and angle detection functions, comprising a torque detection unit and an angle detection unit, wherein the torque detection unit comprises an axially magnetized multi-pole magnetic ring (10), a magnetic flux converging ring (101, 102), an annular bracket (20), a magnetic flux buncher (103, 104) and a first magnetic sensitive element (30), and the angle detection unit comprises a driving gear (40), two driven gear assemblies (51, 52) with different numbers of teeth and a second magnetic sensitive element (61, 62), characterized in that: The driving gear (40) of the rotation angle detection unit is coaxially arranged on the annular bracket (20) of the torque detection unit, and the axial position of the driving gear (40) is arranged below the magnetic flux converging ring (102); there is no meshing intersection of the master / slave gears between the magnetic flux converging rings (101, 102) of the torque detection unit; and the first magnetic sensitive element (30) is arranged in the air gap between the magnetic flux concentrators (103, 104); The driven gear assembly (51, 52) of the rotation angle detection unit comprises a driven gear (513, 523) and a magnetic ring (512, 522); the axial position of the driven gear (513, 523) is arranged below the magnetic flux converging ring (102) and meshes with the driving gear for rotation; The module of the rotation angle detection unit gear is 0.7, and the transmission ratio of the driving gear (40) and the driven gear (513, 523) is ≥3.

33.

2. The integrated sensor structure combining steering wheel torque and angle detection functions according to claim 1 is characterized in that: The radial position of the magnetic ring (512, 522) of the driven gear assembly (51, 52) of the rotation angle detection unit is outside the magnetic flux converging ring (101, 102), and the radial gap (d1, d2) between the magnetic flux converging ring (101, 102) and the magnetic ring (512, 522) of the driven gear assembly (51, 52) is ≥2.5 mm.

3. The integrated sensor structure combining steering wheel torque and angle detection functions according to claim 2 is characterized in that: The magnetic ring (512, 522) of the driven gear assembly (51, 52) has a pair of radially magnetized magnetic poles.

4. The integrated sensor structure combining steering wheel torque and angle detection functions according to claim 3 is characterized in that: The second magnetic sensitive element (61, 62) of the rotation angle detection unit is located above the magnetic ring (512, 522) of the rotation angle detection unit, and the sensitive center A of the second magnetic sensitive element (61, 62) of the rotation angle detection unit coincides with the center of the magnetic ring (512, 522).

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