JP5207703B2 - Drive shaft axial torque measuring device and measuring method - Google Patents

Description

  The present invention relates to a drive wheel axle having a role of transmitting the power of an automobile engine to a wheel, that is, a drive shaft, a device for measuring the shaft torque, a drive shaft equipped with the shaft torque measuring device, and a wheel drive The present invention relates to a unit and a method for measuring shaft torque. As such a drive shaft, a front wheel axle of a front wheel drive vehicle, a rear axle of a rear wheel drive vehicle, and an entire axle of an all wheel drive vehicle are applicable.

In an automobile drive shaft that employs an independent suspension system, it is necessary to transmit a driving force while following the movement of the suspension. For this reason, one end of the drive shaft is connected to the differential via a constant velocity joint, and the other end is connected to an axle (axle) via the constant velocity joint. In this way, the drive shaft is incorporated in a drive system that transmits engine power to the wheels, and the engine power is finally transmitted to the wheels by the drive shaft.
In addition, electronic control technology has been introduced in all parts of recent automobiles, and wheel speed signals are used for driving control such as anti-lock brake system (ABS), traction control system (TCS), and non-slip differential (LSD). ing. For this reason, a pulsar ring for ABS (anti-lock brake system) control is usually provided on the outboard side (axle side) of the drive shaft, and when the gear-shaped pulsar ring rotates as the wheel rotates, A pulse having a frequency proportional to the number of wheel rotations is generated in the electromagnetic pickup installed on the vehicle body side.

In Patent Document 1, a drive shaft of an automobile having constant velocity joints at both ends, and a pulsar ring is attached to each constant velocity joint, that is, an outer ring of each constant velocity joint on the inboard side and the outboard side. A method for measuring the shaft torque of the drive shaft, which detects the rotation signal generated by the above, and calculates the shaft torque by calculating the phase difference of the rotation signal corresponding to the twist generated in the drive shaft, is shown.
In addition, by controlling the engine output based on the obtained shaft torque signal, the generation of excessive torque is prevented, and the generation of this excessive torque prevents weight reduction by reducing the shaft diameter of the drive shaft and the constant velocity joint. It is disclosed.

Further, in Patent Document 2, the outer shaft of a differential-side constant velocity joint in a drive shaft connected at both ends to a vehicle drive system via a constant velocity joint is connected to the drive shaft via a constant velocity joint. Encoders are attached to hubs that are rotation side members of wheel bearings, and sensors that detect the rotation of the encoders are provided opposite to the encoders, and the drive shaft is determined from the phase difference of the rotation signals output by these sensors. A method for obtaining a shaft torque by measuring a torsion amount is disclosed.
Japanese Unexamined Patent Publication No. 7-63628 JP 2004-069332 A

  However, as in the techniques disclosed in Patent Document 1 and Patent Document 2 described above, from the twist angle generated between both ends of the drive shaft or between the rotating side member of the wheel bearing and the constant velocity joint on the differential side. In the case of a configuration that estimates the shaft torque of the drive shaft, the accurate shaft torque is calculated because of mechanical play that occurs inside the constant velocity joint or at the spline joint between the hub of the wheel bearing and the constant velocity joint. Is difficult. In addition, since such mechanical play increases with wear, even if a fixed value is stored in the initial stage, the change due to wear cannot be followed, and it is difficult to ensure detection accuracy.

  An object of the present invention is to provide an axial torque measuring device for a drive shaft capable of accurately detecting an axial torque without being influenced by the presence of mechanical play, a drive shaft with an axial torque measuring device, a wheel driving unit with an axial torque measuring device, And a method for measuring the axial torque of a drive shaft.

The shaft torque measuring device for a drive shaft according to the present invention includes an outer ring of a constant-velocity joint on a differential side of a drive shaft connected to a drive system of an automobile via a constant-velocity joint at both ends, and an other end side of the drive shaft. A sensor target is provided on the outer ring of the constant velocity joint or the rotation side member of the wheel bearing connected through the constant velocity joint, and a sensor for detecting the rotation of each sensor target is provided facing each of the sensor targets. A shaft torque measuring device for a drive shaft that obtains an axial torque of the drive shaft by comparing the outputs of these sensors, a difference calculating means for obtaining a difference between outputs of the sensors, and a difference obtained by the difference calculating means Each sensor target is provided based on the driving state of the car Mechanical play estimation means for estimating the magnitude of mechanical play existing between the materials, data correction means for correcting the difference obtained by the difference calculation means based on the estimated value by the mechanical play estimation means, The present invention is characterized in that there is provided shaft torque calculation means for measuring the torsion angle of the drive shaft from the difference corrected by the data correction means to obtain the shaft torque.
According to this configuration, the mechanical play estimation means estimates the size of the mechanical play based on the difference between the outputs of the two rotation detection devices determined by the difference calculation means and the driving state of the automobile, and the estimation The difference is corrected by the data correction means based on the value, and the shaft torque is obtained by measuring the torsion angle of the drive shaft by the shaft torque calculation means based on the corrected difference value, so that it occurs inside the constant velocity joint or the like. The shaft torque can be accurately detected without being affected by mechanical play. For the estimation by the mechanical play estimation means, for example, a relation setting means such as a table or an arithmetic expression in which the relation between the input and the estimated value is set is provided, and the input is collated with the relation setting means. Get an estimate.

  In the present invention, the mechanical play estimation means includes at least one signal among signals indicating the vehicle speed, the accelerator opening, the brake state, the state of the clutch and the speed reducer as a signal indicating the driving state of the automobile. May be used for the estimation. When these signals indicating the vehicle speed, accelerator opening, brake state, clutch and reducer state, etc. are known, the mechanical play estimation means is in a state where the vehicle is idling or driving torque is applied. It is possible to determine whether or not there is a shaft torque more accurately.

Before Symbol mechanical play estimation means estimates the period in which the operating state of the shaft torque is not applied, the distribution of the twist angle of the drive shaft in the period by statistically processing, calculating the frequency of occurrence and appearance region it is, you estimate the magnitude of the hysteresis component generated difference obtained by the difference calculation means by mechanical play. Thereby, more accurate estimation of the shaft torque can be performed.

In the present invention, each of the sensors is a magnetic sensor, and each of the sensor targets is a magnetic encoder provided concentrically with an installation member thereof, and the magnetic sensors are shifted from each other within a magnetic pole pitch of the magnetic encoder. It may have a plurality of arranged sensor elements and can obtain a signal output of two phases of sin and cos, and it may detect by multiplying the position in the magnetic pole.
In the case of this configuration, the position in the magnetic pole of the magnetic encoder can be detected more finely, and a rotation angle with higher resolution can be detected.

In the present invention, each of the sensors is a magnetic sensor, and each of the sensor targets is a magnetic encoder provided at the same center as its installation member, and the magnetic sensor is a sensor along the magnetic pole alignment direction of the magnetic encoder. It may be constituted by a line sensor in which elements are arranged, and two-phase signal outputs of sin and cos may be generated by calculation, and the position in the magnetic pole is multiplied and detected.
In the case of this configuration, it is possible to detect the phase of the magnetic encoder with higher accuracy by reducing the influence of distortion and noise of the magnetic field pattern. As a result, even if a magnetic encoder with a sufficiently large magnetic pole pitch is used, the phase of the magnetic encoder can be detected with a resolution of several to several tens of times. Can also be detected.

In the present invention, each of the sensors may detect an absolute rotation angle of the sensor target.
Since the phase difference is detected by the time difference in the method of measuring the phase difference by the pulse signal, time for detection is required. On the other hand, in this configuration, since the angle difference is calculated from the absolute rotation angles output from the two sensors and the torsion amount of the drive shaft is measured, the shaft torque can be obtained immediately. Even when the shaft torque is already applied when the power is turned on, the shaft torque at that time can be obtained. As a result, the shaft torque can be accurately detected even in a stationary state, when one end of the drive shaft is stopped or when the rotational speed is extremely low.

In this invention, each said sensor target consists of several magnetic encoders which are provided concentrically with the installation member, and mutually differ in the number of magnetic poles, and each said sensor is the several magnetic sensor which each detects the magnetic field of these magnetic encoders Each of these magnetic sensors has a function of detecting position information in the magnetic pole of the magnetic encoder, and a phase difference detecting means for obtaining a phase difference of the magnetic field signals detected by each of the magnetic sensors; An angle calculating unit that calculates the absolute rotation angle of the sensor target based on the detected phase difference may be included.
In this configuration, since the rotation detection device is a vernier absolute angle detection device, the magnetic encoder pitch is several times the number of magnetic poles while maintaining the same magnetic pole pitch as an ordinary ABS sensor (pole width of about 1 to 3 mm). Rotation can be detected with high resolution of several tens of times, and the mounting tolerance such as sensor gap is kept equivalent to the conventional one (for example, sensor gap of about 0.5 to 2mm), and it is high even in harsh usage environments such as automobiles. Resolution can be obtained. Accordingly, even a slight rotational deviation can be detected, and a minute shaft torque can be detected from the difference in absolute rotation angle detected by both rotation detection devices.

  In the present invention, the magnetic sensor is composed of a line sensor in which sensor elements are arranged along the arrangement direction of the magnetic poles of the magnetic encoder, and generates a two-phase signal output of sin and cos by calculation to obtain a position in the magnetic pole. May be detected by multiplying. In the case of this configuration, it is possible to detect the phase of the magnetic encoder with higher accuracy by reducing the influence of distortion and noise of the magnetic field pattern. As a result, even if a magnetic encoder with a sufficiently large magnetic pole pitch is used, the phase of the magnetic encoder can be detected with a resolution of several to several tens of times. Can also be detected.

  In the present invention, the magnetic sensor, the phase difference detection means, and the angle calculation means of each sensor may be integrated with each other. With this configuration, it is possible to obtain merits such as a reduction in the number of parts, an improvement in magnetic sensor position accuracy, a reduction in manufacturing cost, a reduction in assembly cost, and an improvement in detection accuracy due to signal noise reduction, resulting in a compact and low-cost sensor. be able to.

  In the present invention, the sensor module may be integrated on a semiconductor chip. In this configuration, the mounting space for the sensor module can be small. As a result, for example, in the case of a sensor provided in a wheel bearing, compact mounting on the wheel bearing is possible.

The drive shaft with an axial torque measuring device according to the present invention is obtained by mounting the axial torque measuring device according to any one of the above configurations of the present invention on a drive shaft.
According to this configuration, it is possible to accurately detect the axial torque without depending on the mechanical play that occurs inside the constant velocity joint, and to perform vehicle travel control that supplies the optimum applied torque to the tire. This makes it possible to reduce the weight of the drive shaft.

The wheel drive unit with a shaft torque measuring device according to the present invention is obtained by mounting the shaft torque measuring device according to any one of the above configurations of the present invention on a wheel driving unit including a wheel bearing and a drive shaft.
According to this configuration, the shaft torque can be accurately detected and optimally applied without being influenced by the mechanical backlash generated inside the constant velocity joint or the spline joint between the rotating side member of the wheel bearing and the constant velocity joint. Vehicle running control that supplies torque to the tires is also possible. This makes it possible to reduce the weight of the wheel driving unit.

The shaft torque measurement method for a drive shaft according to the present invention includes: an outer ring of a constant-velocity joint on a differential side in a drive shaft connected to a drive system of an automobile via a constant-velocity joint at both ends; A sensor target is provided on the outer ring of the constant velocity joint or the rotation side member of the wheel bearing connected through the constant velocity joint, and a sensor for detecting the rotation of each sensor target is provided facing each of the sensor targets. A drive shaft axial torque measurement method for obtaining an axial torque of a drive shaft by comparing the outputs of these sensors, wherein a difference between the outputs of the sensors is obtained, and each sensor target is determined from the difference and the driving state of the vehicle. Estimate the size of the mechanical play that exists between the members Based on the estimated value, the correcting a difference between outputs of the sensors, calculated Me a shaft torque by measuring the twist angle of the drive shaft from the corrected difference, as the magnitude of the mechanical play, shaft torque Is estimated by calculating the period of the drive shaft torsion angle distribution during that period, and calculating the frequency of appearance and the area of appearance thereof, thereby making the above-mentioned sensors play mechanically. It is characterized in that the size of a hysteresis component generated in the difference between outputs is estimated .
According to this shaft torque measurement method, the shaft torque can be accurately detected without being affected by the mechanical play that occurs in the constant velocity joint or the spline joint between the rotating side member of the wheel bearing and the constant velocity joint. In addition, it is possible to control the vehicle so that the optimum applied torque is supplied to the tire.

The shaft torque measuring device for a drive shaft according to the present invention includes an outer ring of a constant-velocity joint on a differential side of a drive shaft connected to a drive system of an automobile via a constant-velocity joint at both ends, and an other end side of the drive shaft. A sensor target is provided on the outer ring of the constant velocity joint or the rotation side member of the wheel bearing connected through the constant velocity joint, and a sensor for detecting the rotation of each sensor target is provided facing each of the sensor targets. A shaft torque measuring device for a drive shaft that obtains an axial torque of the drive shaft by comparing the outputs of these sensors, a difference calculating means for obtaining a difference between outputs of the sensors, and a difference obtained by the difference calculating means Each sensor target is provided based on the driving state of the car Mechanical play estimation means for estimating the magnitude of mechanical play existing between the materials, data correction means for correcting the difference obtained by the difference calculation means based on the estimated value by the mechanical play estimation means, The shaft torque calculation means for determining the shaft torque by measuring the torsion angle of the drive shaft from the difference corrected by the data correction means is provided, so that the shaft torque can be accurately detected without being influenced by the presence of mechanical play. .
The drive shaft with an axial torque measuring device according to the present invention is obtained by mounting the axial torque measuring device according to the present invention on the drive shaft, so that the axial torque can be accurately measured without being influenced by the mechanical play generated inside the constant velocity joint. It is also possible to control the vehicle travel so that the optimum applied torque is supplied to the tire, and thus the weight of the drive shaft can be reduced.
The wheel drive unit with a shaft torque measuring device of the present invention is the one in which the shaft torque measuring device of the present invention is mounted on a wheel drive unit including a wheel bearing and a drive shaft. The vehicle torque can be accurately detected and the vehicle running control can be applied to the tire without depending on the mechanical play that occurs at the splined joint of the rotating side member of the wheel bearing and the constant velocity joint. Thus, the wheel drive unit can be reduced in weight.
The shaft torque measuring method according to the present invention includes an outer ring of a constant-velocity joint on a differential side in a drive shaft connected to a drive system of an automobile via a constant-velocity joint at both ends, and a constant-velocity joint on the other end side in the drive shaft. Sensor targets are provided on the outer ring of the wheel or the rotation side member of the wheel bearing connected through the constant velocity joint, and sensors for detecting the rotation of the sensor targets are provided facing the sensor targets. A drive shaft axial torque measurement method for determining the shaft torque of a drive shaft by comparing the output of the sensors of the plurality of sensors, wherein a difference between the outputs of the sensors is obtained, and the sensor targets are provided from the difference and the driving state of the vehicle. Estimate the amount of mechanical play that exists between members, and based on that estimate Since the difference between the outputs of the sensors is corrected, and the torsion angle of the drive shaft is measured from the corrected difference to determine the shaft torque, the inside of the constant velocity joint or the rotation side member of the wheel bearing Thus, the vehicle torque can be accurately detected without depending on the mechanical play generated at the spline coupling portion with the constant velocity joint, and the vehicle running control can be performed so that the optimum applied torque is supplied to the tire.

  An embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the drive shaft 1 is connected to a drive system via constant velocity joints 2 and 3 at both ends. In this specification, the side closer to the outer side in the vehicle width direction (left side in the figure) when the drive shaft 1 is attached to the vehicle is called the outboard side, and the side that is the center side in the vehicle width direction (in the figure) The right side) is called the inboard side. In the illustrated embodiment, the inboard side of the drive shaft 1 is connected to a differential (not shown) by a triport type slide type constant velocity joint 2, and the outboard side is connected to an axle (not shown) by a barfield type fixed type constant velocity joint 3. (Not shown).

  In addition, the constant velocity joints at both ends of the drive shaft 1 are not limited to the combinations as illustrated in the drawing. For example, in the case of the front wheel axle of the front wheel drive vehicle, that is, the front wheel axle, the front wheel is steered, and therefore the constant velocity joint 3 on the outboard side that is the wheel side is required to have a constant operating speed with a large operating angle. In order to satisfy this requirement, a barfield type fixed joint (zeppa type fixed joint), a tripod type fixed constant velocity joint, or the like is used for the constant velocity joint 3 on the outboard side. The constant velocity joint 2 on the inboard side that is the vehicle body side is required to have an operating angle that allows the suspension to move. This operating angle is not as large as that of the wheel side constant velocity joint 3, but it is necessary to enable the change of the length of the vehicle body with the movement of the suspension. For this reason, for the inboard side constant velocity joint 2, a Barfield type sliding joint, a tripart type sliding joint, a cross glove type joint, or the like is used. Since the independent suspension type drive wheel rear axle does not require a steering function and does not require a large operating angle, a cardan joint may be used.

  A sensor target 5 that is also used for ABS (anti-lock brake system) control is attached to the outer ring 3a of the constant velocity joint 3 on the outboard side. The same type of sensor target 4 is also attached to the outer ring 2a of the constant velocity joint 2 on the inboard side. On the vehicle body 40 side, sensor units 6 and 7 including a plurality (here, two) of magnetic sensors 11A and 11B (FIG. 3) are installed at positions close to these sensor targets 4 and 5. The sensor target 4 and the sensor unit 6 constitute a first rotation detection device 8 that outputs an absolute rotation angle corresponding to the rotation position of the sensor target 4. The sensor target 5 and the sensor unit 7 constitute a second rotation detection device 9 that outputs an absolute rotation angle corresponding to the rotation position of the sensor target 5. Thus, the corresponding sensor units 6 and 7 are arranged on the outer peripheral side of the drive shaft 1 in a non-contact state with respect to the sensor targets 4 and 5 provided on the outer rings 2 and 3 a of the constant velocity joints 2 and 3. Thus, the rotation detection devices 8 and 9 can be mounted compactly on the drive shaft 1.

As shown schematically in FIG. 3, the sensor target 4 includes a plurality of (here, two) magnetic encoders provided on the outer ring 2 a of the constant velocity joint 2 in a ring shape concentric with the axis O. 4A and 4B. In the example of FIG. 3, the two magnetic sensors 11A and 11B of the sensor unit 6 corresponding to the sensor target 4 are respectively in the radial direction (radial direction) via a minute gap with respect to the magnetic encoders 4A and 4B. It is provided on the vehicle body 40 side so as to face each other.
Similarly, the sensor target 5 includes a plurality (two in this case) of magnetic encoders 5A and 5B provided on the outer ring 3a of the constant velocity joint 3 in a ring shape concentric with the axis O. The two magnetic sensors 11A and 11B of the sensor unit 7 corresponding to the sensor target 5 are also provided on the vehicle body 40 side so as to face each of the magnetic encoders 5A and 5B in the radial direction through a small gap. It is done. Here, the magnetic sensor 11A faces the magnetic encoder 4A (5A), and the magnetic sensor 11B faces the magnetic encoder 4B (5B).

  The magnetic encoders 4A and 4B (5A and 5B) are ring-shaped magnetic members in which a plurality of magnetic pole pairs (one set of magnetic poles S and N) are magnetized at equal pitches in the circumferential direction, and are of a radial type. In the example of 3, the magnetic pole pair is magnetized on the outer peripheral surface. The number of magnetic pole pairs of these two magnetic endors 4A and 4B (5A and 5B) is different from each other.

  As another example of the magnetic encoders 4A and 4B (5A and 5B), as shown in FIG. 4, a plurality of magnetic pole pairs are magnetized so as to be arranged at equal pitches in the circumferential direction on the end surface in the axial direction of the ring-shaped magnetic member. An axial type may also be used. In this example, two magnetic encoders 4A and 4B (5A and 5B) are arranged adjacent to the inner and outer peripheries. In the case of the axial type magnetic encoders 4A and 4B (5A and 5B), the magnetic sensors 11A and 11B are arranged in the axial direction facing the magnetized surface.

The magnetic sensors 11A and 11B have a function capable of detecting magnetic poles with a resolution higher than the number of magnetic pole pairs of the corresponding magnetic encoders 4A and 4B (5A and 5B), that is, within the range of the magnetic poles of the magnetic encoders 4A and 4B (5A and 5B). It has a function of detecting position information at. In order to satisfy this function, for example, the magnetic sensor 11A may be configured as shown in FIG. 5 when the pitch λ of one magnetic pole pair of the corresponding magnetic encoder 4A (5A) is one period. That is, two magnetic sensor elements 11A1 and 11A2 such as Hall elements arranged apart from each other in the arrangement direction of the magnetic poles so as to have a phase difference of 90 degrees (λ / 4) are used, and obtained by these two magnetic sensor elements 11A1 and 11A2. It may be calculated by multiplying the phase in the magnetic pole (φ = tan ⁻¹ (sinφ / cos φ)) from the two-phase signal (sinφ, cosφ). The same applies to the other magnetic sensor 11B. The waveform diagram of FIG. 5 shows the arrangement of the magnetic poles of the magnetic encoder 4A (5A) in terms of magnetic field strength.

  When the magnetic sensors 11A and 11B have such a configuration, the magnetic field distribution of the magnetic encoders 4A and 4B (5A and 5B) is not as an on / off signal, but as a sinusoidal signal based on an analog voltage, the position in the magnetic pole is more finely defined. The phase of the magnetic encoders 4A and 4B (5A and 5B) can be detected with higher accuracy. In this case, in order to reduce the influence of magnetic noise, the two magnetic sensor elements 11A1 and 11A2 may have a differential configuration so as to obtain a more stable signal.

  As another example of the magnetic sensors 11A and 11B having a function of detecting position information in the magnetic poles of the magnetic encoders 4A and 4B (5A and 5B), a line sensor as shown in FIG. 6B may be used. . That is, for example, as the magnetic sensor 11A, line sensors 11AA and 11AB in which the magnetic sensor elements 11a are arranged along the arrangement direction of the magnetic poles of the corresponding magnetic encoders 4A and (5A) are used. FIG. 6A is a waveform diagram in which a section of one magnetic pole in the magnetic encoder 4A (5A) is converted into a magnetic field strength. In this case, the first line sensor 11AA of the magnetic sensor 11A is arranged in association with the 90-degree phase section of the 180-degree phase section in FIG. 6A, and the second line sensor 11AB is the remaining 90. It is arranged in correspondence with the phase interval of degrees. With such an arrangement, the signal S1 obtained by adding the detection signal of the first line sensor 11AA by the adder circuit 31 and the signal S2 obtained by adding the detection signal of the second line sensor 11AB by the adder circuit 32 are different addition circuits. By adding in 33, a sin signal corresponding to the magnetic field signal as shown in FIG. 6C is obtained. Further, the signal S1 and the signal S2 via the inverter 35 are added by another adding circuit 34 to obtain a cos signal corresponding to the magnetic field signal as shown in FIG. The position in the magnetic pole is detected from the two-phase output signal thus obtained.

  When the magnetic sensors 11A and 11B are configured by line sensors in this way, the effects of distortion and noise of the magnetic field pattern are reduced, and the phases of the magnetic encoders 4A and 4B (5A and 5B) can be detected with higher accuracy. Is possible. In this case, even when the magnetic encoders 4A and 4B (5A and 5B) having a sufficiently large magnetic pole pitch are used, the phases of the magnetic encoders 4A and 4B (5A and 5B) can be detected with a resolution several times to several tens of times. Since it is possible, even a slight twist angle of the drive shaft 1 due to a small torque can be detected.

  In FIG. 3 showing a configuration example of the rotation detection device 8 (9), the magnetic sensors 11 A and 11 B constituting the sensor unit 6 (7) are connected to the phase difference detection means 12. The phase difference detection means 12 is a means for obtaining the phase difference of the magnetic field signals detected by the magnetic sensors 11A and 11B, and the angle calculation means 13 is connected to the subsequent stage. The angle calculation means 13 is a means for calculating the absolute angle of the magnetic encoders 4A, 4B (5A, 5B) based on the phase difference detected by the phase difference detection means 12.

  Further, in each of the rotation detection devices 8 and 9, the magnetic sensors 11A and 11B, the phase difference detection means 12, and the angle calculation means 13 may be integrated as a sensor module 24 as shown in the example of FIG. good. When configured in this way, advantages such as a reduction in the number of components, an improvement in the positional accuracy of the magnetic sensors 11A and 11B, a reduction in manufacturing costs, a reduction in assembly costs, and an improvement in detection accuracy due to signal noise reduction can be obtained. The rotation detectors 8 and 9 can be made small and low cost. The sensor module 24 may be integrated on one semiconductor chip. If comprised in this way, the mounting space of the sensor module 24 may be small. As a result, a compact mounting on the drive shaft 1 is possible.

  FIG. 2 shows a schematic configuration of the drive shaft axial torque measuring apparatus. The angle calculation units 14 and 15 in the figure are functional units including the phase difference detection unit 12 and the angle calculation unit 13 in FIG.

  A schematic operation of absolute angle detection by each of the rotation detection devices 8 and 9 will be described below with reference to FIGS. In FIG. 3, assuming that the number of magnetic pole pairs of the two magnetic encoders 4A and 4B (5A and 5B) is P and P + n, the number of magnetic pole pairs between one magnetic encoder 4A and 4B (5A and 5B) is n. Since there is a phase difference corresponding to the number, the phases of the detection signals of the magnetic sensors 11A and 11B corresponding to the magnetic encoders 4A and 4B (5A and 5B) coincide with each other by rotating 360 / n degrees.

7A and 7B show examples of magnetic pole patterns of both magnetic encoders 4A and 4B (5A and 5B), and FIGS. 8C and 8D show these magnetic encoders 4A and 4B (5A, 5B). 5B shows a waveform diagram of detection signals of the magnetic sensors 11A and 11B corresponding to 5B). In this case, the two magnetic pole pairs of the magnetic encoder 4B (5B) correspond to the three magnetic pole pairs of the magnetic encoder 4A (5A), and the absolute position in this section can be detected. FIG. 7E shows a waveform diagram of the output signal of the phase difference obtained by the phase difference detecting means 12 of FIG. 3 based on the detection signals of FIGS. 7C and 7D.
In addition, FIG. 8 shows the waveform diagram of the detection phase and phase difference by each magnetic sensor 11A, 11B. 8A and 8B show examples of magnetic pole patterns of both magnetic encoders 4A and 4B (5A and 5B), and FIGS. 8C and 8D show corresponding magnetic sensors 11A and 11B. FIG. 8E shows a waveform diagram of the phase difference signal output from the phase difference detection means 12.

  FIG. 9 shows a configuration example of an absolute angle detection circuit in each of the rotation detection devices 8 and 9. Based on the detection signals of the magnetic sensors 11A and 11B as shown in FIGS. 7C and 7D, the corresponding phase detection circuits 23A and 23B are as shown in FIGS. 8C and 8D, respectively. Output an accurate detection phase signal. The phase difference detection means 12 outputs a phase difference signal as shown in FIG. 8E based on these detected phase signals. The angle calculation means 13 provided at the next stage performs processing for converting the phase difference obtained by the phase difference detection means 12 into an absolute angle according to a preset calculation parameter.

  In the configuration of FIG. 2, the difference calculation means 16 is a means for obtaining a difference between the absolute rotation angles detected by the rotation detection devices 8 and 9. The data correction unit 17 is a unit that corrects the difference obtained by the difference calculation unit 16. Details of the correction processing by the data correcting means 17 will be described below with reference to FIGS.

  In the drive shaft 1 of FIG. 1, there is mechanical play inside the constant velocity joints 2 and 3 at both ends. Due to this mechanical play and friction, the shaft torque applied to the drive shaft 1 and the torsion angle (difference in absolute rotation angle obtained by the difference calculating means 16) are not proportional, and are nonlinear with hysteresis as shown in FIG. It becomes a relationship. For this reason, if the axial torque is directly calculated from the twist angle of the drive shaft 1 obtained as a difference by the difference calculating means 16, the detection error becomes large. Further, since the mechanical play inside the constant velocity joints 2 and 3 gradually changes due to wear or the like, the angle values of the mechanical play as shown by D1 and D2 in FIG. 10 also change gradually. End up. On the other hand, the inclination of the graph of FIG. 10 in a state where the axial torque is applied does not change. FIG. 11 is a waveform diagram showing an example of shaft torque (FIG. 11A) and detected angle difference (FIG. 11B) in a certain operating state.

Therefore, by estimating the magnitude of the mechanical hysteresis indicated by D1 and D2 in FIG. 10 from the driving state of the automobile and the detected angle difference data, the difference value obtained by the difference calculating means 16 is obtained. If the correction is made, it is possible to eliminate a decrease in detection accuracy caused by mechanical play. The controller 21 in FIG. 2 is a means for controlling processing of the data correction means 17, shaft torque calculation means 18 and initial angle holding means 20, which will be described later, and this controller 21 is detected as the driving state of the automobile. A mechanical play estimating means 22 for estimating the magnitude of the mechanical hysteresis from the angle difference data is provided. For the estimation by the mechanical play estimation means 22, for example, a relation setting means (not shown) such as a table or an arithmetic expression in which the relation between the input and the estimated value is set is provided, and the input is collated with the relation setting means. Thus, the estimated value is obtained. In the relationship setting means, an appropriate relationship may be obtained and set in advance through experiments or simulations.
The mechanical play estimation means 22 receives signals indicating the driving state of the automobile such as the vehicle speed, the accelerator opening, the brake state, the state of the clutch and the speed reducer from the vehicle travel control device on the vehicle body side. Based on this input, the mechanical play estimation means 22 determines whether the automobile is in an idling state or a state where a driving torque is applied, and is used for estimation.

  In a state where the driving torque is not applied as in the idling state or in a very small torque state, the twist angle easily changes in the range of D1 to D2 in the graph of FIG. When the shaft torque T1 is applied as shown in FIG. 11A, the drive shaft 1 is twisted, which corresponds to the shaft torque to which a twist angle exceeding D1 is applied as shown in FIG. 11B. When the input shaft torque changes to T2, the torsion angle changes in the reverse direction by skipping D1 to D2, and corresponds to the applied shaft torque T2 that exceeds D2 in FIG. When the input shaft torque disappears again, the state easily changes in the range from D1 to D2 in FIG.

  Therefore, the mechanical play estimating means 22 of the controller 21 monitors the movement of the detected torsion angle during a period when it is determined that the shaft torque is not applied from the operating state together with the data correcting means 17, and the appearance frequency and output range thereof. To estimate the values of D1 and D2. Since the values of D1 and D2 are determined by mechanical play or the like, they do not change so rapidly and frequently. Therefore, it is possible to improve the accuracy of the estimated value by analyzing the trend of data over a long period of time. The data correction means 17 uses the estimated values D1 and D2 to obtain the relationship between the shaft torque and the twist angle in FIG. 10, and the difference value (twist angle) obtained by the difference calculation means 16 from this relationship. Can be corrected to an accurate value.

  The shaft torque calculating means 18 in FIG. 2 is a means for measuring the twist amount of the drive shaft 1 from the difference value corrected by the data correcting means 17 and calculating the shaft torque from the twist amount. The output circuit 19 is a means for outputting the shaft torque obtained by the shaft torque calculating means 18 to the outside. The initial angle difference holding means 20 is means for holding the initial angle difference of the absolute rotation angle detected by each of the rotation detection devices 8 and 9 in a state where no axial torque is applied to the drive shaft 1. The difference calculating means 16 performs correction for subtracting the obtained absolute rotation angle difference by the initial angle difference held by the initial angle difference holding means 20.

A shaft torque measuring method using the shaft torque measuring device having the above configuration will be described.
The shaft torque generated in the drive system is large at the time of sudden start and acceleration of the automobile, and the drive shaft 1 has the lowest rigidity except for the clutch portion in the drive systems of the four-wheeled and two-wheeled vehicles. Therefore, the drive shaft 1 is twisted. The torsion angle is measured from the difference between the absolute rotation angles detected by the rotation detection devices 8 and 9, and the shaft torque is obtained.

  Since the two rotation detection devices 8 and 9 can detect the absolute rotation angle at their installation position, angle data can be directly obtained from each rotation detection device 8 and 9. The output from the sensor units 6 and 7 in each of the rotation detection devices 8 and 9 may be a pulse signal such as the ABZ signal shown in FIG. 2, and the angle immediately after the power is turned on is acquired by data and the rotation is started. Then, a method of counting pulse signals may be used.

  Since each rotation detection device 8 and 9 is configured to detect rotation at an absolute angle, even when the shaft torque is already applied when the power is turned on, the shaft torque at that time can be detected. it can. Therefore, for example, it is possible to detect a state in which the engine torque is transmitted to the road surface through the tire at the start of the automobile, and it is possible to improve driving ease and safety by advanced engine control, clutch control, and the like.

In addition, if the rotation detection devices 8 and 9 output a pulse signal and the angle is calculated by counting the pulse signal, the angle difference will be accumulated and remain if erroneously counted even once. Although it becomes a torque offset value, in this shaft torque measuring device that detects an absolute angle, the angle difference is always updated and obtained, so the above-mentioned problem does not occur.
In addition, since the phase difference is detected by the time difference in the phase difference measurement method using the pulse signal, it takes time for detection. In the case of this shaft torque measuring device that calculates the angle difference from the absolute rotation angle, The shaft torque can be obtained, and there is no detection time delay that adversely affects vehicle control.

  Further, in the configuration of FIG. 2, an initial angle difference holding means 20 is provided that holds the initial angle difference of the absolute rotation angle detected by each of the rotation detection devices 8 and 9 when no axial torque is applied to the drive shaft 1. Since the difference between the absolute rotation angles obtained by the difference calculation means 16 (value corrected by the data correction means 17) is corrected by subtracting only the initial angle difference held by the initial angle difference holding means 20, Regardless of whether the drive shaft 1 is rotating or stationary, it is possible to accurately detect the twist of the drive shaft 1.

  Further, since the rotation detection devices 8 and 9 are vernier absolute angle detection devices, the magnetic pole pitches of the magnetic encoders 4A and 4B (5A and 5B) are equivalent to those of a normal ABS sensor or the like (a pole width of about 1 to 3 mm). The rotation can be detected with high resolution several times to several tens of times the number of magnetic poles. For this reason, high resolution can be obtained even in a harsh use environment such as an automobile while maintaining mounting tolerances such as a sensor gap equal to the conventional one (for example, a sensor gap of about 0.5 to 2 mm). Therefore, even a slight rotational deviation can be detected, and a minute shaft torque can also be detected from the difference in absolute rotation angle detected by both rotation detection devices 8 and 9.

  Also, since there are two-phase signals before multiplication inside the rotation detectors 8 and 9, the rotation direction can be determined by this signal, and the axial torque in either positive or negative direction can be detected. Is possible. In addition, shaft torque can be detected along with the direction of rotation, even for small forwards and backwards when driving on hills, so the ease of driving the vehicle is improved by optimal brake control and torque control according to conditions. It becomes possible.

  In particular, in this shaft torque measurement method, the difference between the outputs (absolute rotation angles) of the two rotation detectors 8 and 9 is obtained by the difference calculation means 16, and the two constant velocity joints are calculated based on the difference and the driving state of the vehicle. The size of the mechanical play existing between 2 and 3 is estimated by the mechanical play estimation means 22, the difference is corrected by the data correction means 17 based on the estimated value, and based on the corrected difference value Since the shaft torque calculation means 18 measures the torsion angle of the drive shaft 1 to obtain the shaft torque, the shaft torque can be accurately determined without being influenced by the mechanical play generated inside the constant velocity joints 2 and 3. It is possible to detect the vehicle and control the vehicle to supply the optimum applied torque to the tire. As a result, the drive shaft 1 can be reduced in weight.

  12 to 16 show another embodiment of the present invention. Also in this embodiment, the rotation detectors 8 and 9 are installed at the constant velocity joints 2 and 3 at both ends of the drive shaft 1 shown in FIG. Here, each of the sensor targets 4 and 5 has, for example, a plurality of magnetic pole pairs arranged at equal positions in the circumferential direction of the peripheral surface as shown in the half sectional view and the perspective view in FIGS. It consists of one ring-shaped magnetic encoder magnetized side by side, and is attached so as to be concentric with the constant velocity joint outer rings 2a and 3a. Each sensor unit 6, 7 has one magnetic sensor 11 and a multiplier circuit 25 as shown in FIG. 13. In the case of the sensor targets 4 and 5 in FIG. 14, the magnetic sensors 11 of the sensor units 6 and 7 are opposed to the peripheral surfaces so that the magnetic poles N and S of the sensor targets (magnetic encoders) 4 and 5 can be directly detected. Arranged on the outer diameter side.

  The configuration example of the sensor targets (magnetic encoders) 4 and 5 in FIG. 14 is a radial type, but it may be an axial type as shown in FIGS. 15A and 15B with a half sectional view and a perspective view. . In the configuration example of FIG. 15, for example, a plurality of magnetic pole pairs are equally arranged in the circumferential direction of the side surface of the flange portion 10b extending from one end of the cylindrical portion 10a of the ring-shaped back metal 10 having an L-shaped cross section to the outer diameter side. The magnets are arranged side by side and magnetized so as to be concentric with the constant velocity joint outer ring 2a (3a) by fitting the cylindrical portion 10a of the back metal 10 to the constant velocity joint outer ring 2a (3a). It is attached. In this case, the magnetic sensor 11 is arranged in the axial direction so as to face the magnetized surfaces of the sensor targets (magnetic encoders) 4 and 5. In addition to the above-described magnetic encoder, a pulsar ring made of a gear-like magnetic material may be used as the sensor targets 4 and 5.

  FIG. 12 shows a schematic configuration of the shaft torque measuring device for the drive shaft of this embodiment, and FIG. 13 shows a schematic configuration of the rotation detecting devices 8 and 9. As described above, the rotation detection devices 8 and 9 include the sensor targets 4 and 5 and the sensor units 6 and 7 disposed to face the sensor targets 4 and 5. Each sensor unit 6, 7 generates a high-resolution rotation pulse by multiplying one magnetic sensor 11 that directly detects the rotation of each opposing sensor target 4, 5 and the rotation signal output from this magnetic sensor 11. And a multiplier circuit 25.

  Also in this embodiment, the magnetic sensor 11 has a function capable of magnetic detection with higher resolution than the magnetic pole pair of the corresponding sensor target (magnetic encoder) 4, 5, that is, position information within the magnetic pole range of the sensor target 4, 5. It is assumed that it has a function of detecting. In order to satisfy this function, for example, the magnetic sensor 11 of the configuration example of FIG. 5 described in the previous embodiment or a line sensor as shown in FIG. 6 is used. In the case of the magnetic sensor 11 having the configuration example of FIG. 5, the multiplication circuit 25 in FIG. 13 outputs a rotation pulse as multiplication position information in the magnetic poles of the sensor targets (magnetic encoders) 4 and 5. In the case of the magnetic sensor 11 including the line sensor of FIG. 6, the obtained two-phase output signals sin and cos are processed by, for example, the multiplication circuit 25 having the configuration shown in FIG. Get a rotation pulse.

16 includes a signal generating means 41, a sector detecting means 42, a multiplexer means 43, and a fine interpolation means 44.
The signal generation means 41 has the same amplitude A0 and the same average value C0 from the two-phase signal sin, cos which is the output of the magnetic sensor 11, m is a positive integer less than n, and i is 1. as to 2 ^m-1 positive integer, phase by 2π / 2 ^m-1 with each other one after another are shifted, a means for generating a 2 ^m-1 pieces of signal si.
The sector generating means 42 generates m digital signals bn-m + 1, bn-m + 2,..., Bn-1, bn coded to define 2 ^m equal sectors Pi. This means is for detecting 2 ^m sectors Pi divided by 2 ^m-1 signals si.
The multiplexer means 43 is controlled by the m digital signals bn-m + 1, bn-m + 2,..., Bn-1 and bn generated from the sector generating means 42, and is generated from the signal generating means 41. 2 ^m−1 of the above-mentioned signals si are processed, and the amplitude is constituted by a portion of the series of 2 ^m−1 of the signals si between the average value C0 and the first threshold value L1. One signal A, the amplitude of which is between the first threshold value L1 of the series of 2 ^m-1 signals si and the second threshold value L2 higher than this threshold value. This is an analog means for generating the other signal B constituted by the portion.
Fine interpolation unit 44, in order to obtain the desired resolution, the angle 2 [pi / 2 2 ^m pieces of each angle 2π / 2 2 ^nm number code to subdivide the same sub-sector of the ⁿ of the sector Pi of ^m Generated from the multiplexer means 43 in each of the 2 ^m sectors Pi to generate (n−m) digital signals b 1, b 2,..., B nm−1, b n−m. Means for finely interpolating the one signal A and the other signal B.
By the multiplication circuit 25, the two-phase signal sin, cos obtained by the magnetic sensor 11 is a (n−m) number of digital signals b1, b2,..., B nm−1, bn-m, which are multiplication signals. (Here b1, b2,..., B8, b9).

  In the configuration of FIG. 12, the rotation pulse difference calculation means 26 is means for counting the rotation pulses generated by the multiplication circuits 25 of the sensor units 6 and 7 and obtaining the difference between these count values. The rotation pulse difference calculation means 26 is generated by a first counter 27 that counts rotation pulses generated by the multiplication circuit 25 on the first rotation detection device 8 side and a multiplication circuit 25 on the second rotation detection device 9 side. A second counter 28 that counts the rotation pulses to be rotated, and an angle difference calculation means 16 that calculates the difference between the count values of both the counters 27 and 28.

The data correction circuit 17, the shaft torque calculation means 18, the output circuit 19, and the mechanical play estimation means 22 of the controller 21 are the same functional units as in the previous embodiment, and the description thereof is omitted here.
The controller 21 includes an offset cancel unit 29 and a count value reset unit 30 in addition to the mechanical play estimation unit 22. The offset cancel means 29 is operated by the shaft torque calculation means 18 based on the difference between the rotation pulses obtained by the rotation pulse difference calculation means 26 and predetermined data indicating the driving state sent from the vehicle travel control device. This is a means for canceling the steady offset included in the required shaft torque. The count value resetting means 30 is a means for resetting the count values counted by the counters 27 and 28 in the rotation pulse difference calculating means 26 in an operating state where no shaft torque is applied.

A shaft torque measuring method using the shaft torque measuring device having the above configuration will be described.
In each of the rotation detectors 8 and 9 in FIG. 12, the rotation position of each sensor target 4 and 5 is detected by the magnetic sensor 11 and the rotation signal output from the magnetic sensor 11 is multiplied by the multiplication circuit 25 as shown in FIG. Thus, a high-resolution rotation pulse is generated. That is, also in the case of this embodiment in which each of the sensor targets 4 and 5 is configured by one magnetic encoder, the sensor units 6 and 7 (FIG. 13) including the magnetic sensor 11 and the multiplication circuit 25 are the sensor target (magnetic encoder). ) It has a multiplication function for generating a rotation pulse several times to several tens of times the number of magnetic poles 4 and 5. Thereby, the rotation of the drive shaft 1 can be detected with high resolution. In this case, the rotation pulse generated by any one of the multiplication circuits 25 of the sensor units 6 and 7 may be two A-phase and B-phase pulse signals whose phases are 90 ° different from each other. good. Since the rotation direction can be discriminated by these two-phase signals, it is possible to detect the axial torque in either positive or negative direction. In addition, shaft torque can be detected along with the direction of rotation, even for small forwards and backwards when driving on hills, so the ease of driving the vehicle is improved by optimal brake control and torque control according to conditions. It becomes possible.

  The rotation pulses that are the outputs from the rotation detectors 8 and 9 are counted by the counters 27 and 28, respectively, and held at the respective angle count values. In this case, if the rotation pulse is a phase difference signal such as the above-described AB phase signal, it is possible to deal with both positive and negative rotation directions, which is more convenient. The angle difference calculation means 16 calculates the difference between the count values held in the counters 27 and 28. The data correction means 17 corrects the difference value obtained by the difference calculation means 16 based on the magnitude of the mechanical play estimated by the mechanical play estimation means 22 of the controller 21 as in the previous embodiment. To do. The shaft torque calculating means 17 measures the twist amount of the drive shaft 1 from the corrected difference value of the rotation pulse, and calculates the shaft torque corresponding to the twist amount in accordance with a preset parameter. The obtained shaft torque value is output to the outside by the output circuit 18 as a data format through a communication interface such as a voltage value, a current value, a PWM signal, or a CAN bus.

  As described above, since the shaft torque is obtained by calculating from the rotation pulses output from the rotation detectors 8 and 9, one of the wheels is stopped, which is impossible by the method of detecting the signal phase difference. It is also possible to detect shaft torque.

  The sensor units 6 and 7 of the two rotation detection devices 8 and 9 may have different resolutions. In this case, the two counters 27 and 28 in FIG. 12 change at different speeds. Therefore, before obtaining the difference between the respective count values, each counter value is multiplied by a constant so as to be a common multiple of the two values. You just have to keep the speed the same.

  Thus, in the method of counting the rotation pulses and holding the current rotation angle of the drive shaft 1 as the count value, a steady offset occurs in the count value due to mechanical play, or the counters 27, The count value of 28 may shift and an error may occur in the shaft torque calculation. Therefore, in this embodiment, the offset canceling means 29 in the controller 21 monitors the torque output value of the shaft torque calculating means 18, that is, the angle difference, and, for example, data relating to the driving state separately provided from the vehicle travel control device (acceleration / deceleration state) The stationary offset is extracted by performing a filtering process in accordance with the engine speed, etc., and the offset is removed in the calculation process by the shaft torque calculation means 18. Thereby, the influence of the offset generated by mechanical play or the like can be reduced, and an accurate shaft torque can be detected.

  Moreover, in this embodiment, the count value reset means 30 in the controller 21 performs a process of periodically resetting the counters 27 and 28 at the timing of the operating state in which no shaft torque is applied. In addition, the erroneous count value accumulated in the counters 27 and 28 may be reset. Thereby, the influence of the noise integrated in the counters 27 and 28 can be removed, and an accurate shaft torque can be detected. When the rotation pulse output from the rotation detectors 8 and 9 includes an index signal Z such as an ABZ signal, an erroneous count due to noise or the like is reset once per rotation. It is not necessary to issue a reset command from the numerical cancellation means 30.

  As described above, according to the method for measuring the shaft torque of the drive shaft, the minute torsion angle of the drive shaft 1 can be detected with high resolution, and the decrease in detection accuracy due to mechanical play can be eliminated. It is possible to detect the vehicle and control the vehicle to supply the optimum applied torque to the tire. Thereby, it can contribute also to the weight reduction of the drive shaft 1. FIG. Further, since the detection method counts the rotation pulses, it can be detected even if one of the two sensor targets 4 and 6 is stopped. Therefore, for example, it is possible to detect a state in which the engine torque is transmitted to the road surface through the tire at the start of the automobile, and it is possible to improve driving ease and safety by advanced engine control, clutch control, and the like.

  17 to 19 show still another embodiment of the present invention. FIG. 17 shows a vehicle wheel drive unit including a drive shaft 1 and a wheel bearing 50. The drive shaft 1 is connected to a drive system via constant velocity joints 2 and 3 at both ends. In this embodiment, the inboard side of the drive shaft 1 is connected to a differential (not shown) by a triport type slide type constant velocity joint 2, and the outboard side is a wheel bearing by a barfield type fixed type constant velocity joint 3. It is connected to 50 inner members 52.

  18 is an enlarged longitudinal sectional view showing a portion on the wheel bearing 50 side in FIG. This wheel bearing 50 has a double row rolling element 53 interposed between an outer member 51 and an inner member 52, and supports the wheel rotatably with respect to the vehicle body.

  The outer member 51 is a fixed member, and the inner member 52 is a rotating member. The rolling elements 53 of each row are held by the cage 54 for each row, and are formed on the outer circumference of the inner row 52 and the double row rolling surfaces 55 formed on the inner circumference of the outer member 51. Further, it is interposed between the double row rolling surfaces 56. The wheel bearing 50 is a double-row angular contact ball bearing type, and the rolling surfaces 55, 55, 56, and 56 of both rows are formed so that the contact angles are back to back.

The example of FIG. 18 is an example of a so-called fourth generation type, and the inner member 52 is configured by the hub wheel 57 and the outer ring 3 a of the constant velocity joint 3.
The constant velocity joint 3 is formed by forming a plurality of track grooves along the axial direction on the spherical inner surface of the outer ring 3a and the spherical outer surface of the inner ring 3b, and interposing a torque transmission ball 83 between the opposed track grooves. . The torque transmission ball 83 is held by the holder 84. The inner ring 3b is fitted to the drive shaft 1. As for the outer ring | wheel 3a of the constant velocity joint 3, the hollow shaft-shaped stem part 3ab protrudes from the outer bottom face of the cup part 3aa. The stem portion 3ab is inserted into the hub wheel 57 of the wheel bearing 50, and is integrally coupled to the hub wheel 57 by diameter expansion caulking. A rolling surface 56 of each row of the inward members 52 is formed on the hub wheel 57 and the outer ring 3 a of the constant velocity joint 3. A bellows-like boot 87 is placed between the opening of the cup portion 3aa of the outer ring 3a of the constant velocity joint 3 and the outer periphery of the drive shaft 1.
The hub wheel 57 has a wheel mounting flange 57b on the outer periphery in the vicinity of the end portion on the outboard side, and a wheel and a brake rotor (both not shown) are attached to the wheel mounting flange 57b by a hub bolt 59. The hub bolt 59 is press-fitted into a bolt mounting hole provided in the wheel mounting flange 57b. The outer member 51 is an integral member as a whole, and has a vehicle body mounting flange 51b on the outer periphery. The outer member 51 is attached to a knuckle (not shown) of the suspension device by a knuckle bolt inserted through the bolt hole 60 of the vehicle body attachment flange 51b.
Both ends of the bearing space between the outer member 51 and the inner member 52 are sealed by sealing devices 61 and 62 such as contact seals.

The sensor target 5 described in the previous embodiment is attached to the outer peripheral surface of the inner member 52 that is a member on the rotation side of the wheel bearing 50. As shown in FIG. 17, the same type of sensor target 4 is also attached to the outer ring 2 a of the constant velocity joint 2 on the inboard side of the drive shaft 1. A sensor unit 6 is installed at a predetermined position on the vehicle body 40 side close to the sensor target 4. The sensor unit 6 and the sensor target 4 constitute a first rotation detection device 8 that outputs an absolute rotation angle corresponding to the rotation position of the sensor target 4. The sensor unit 7 is also installed at a position close to the sensor target 5 attached to the outer peripheral surface of the inner member 52 of the wheel bearing 50, that is, at the outer member 51 of the wheel bearing 50. The sensor unit 7 and the sensor target 5 constitute a second rotation detection device 9 that outputs an absolute rotation angle corresponding to the rotation position of the sensor target 5. In this manner, the corresponding sensor units 6 and 7 are connected to the outer ring 2a and the outer ring 2a of the constant velocity joint 2 and the sensor targets 4 and 5 attached to the inner member 52 of the wheel bearing 50 in a non-contact state. By arrange | positioning on the outer peripheral side of the inward member 52, each said rotation detection apparatus 8 and 9 can be mounted compactly with respect to the unit for wheel drive.
For the in-board side rotation detection device 8 in which the sensor target 4 is mounted on the outer ring 2a of the constant velocity joint 2, the mounting position is the rotation of the driving component to which the constant velocity joint 2 is coupled, such as a bearing portion in the differential case. You may provide in the position which can detect. For example, a bearing with a built-in rotation sensor may be used. Although the detailed configuration of these rotation detection devices 8 and 9 is not mentioned, even the vernier absolute angle detection device in the case of the embodiment shown in FIGS. 1 to 11 is the embodiment shown in FIGS. The configuration in this case may be used.

  As shown in FIG. 18, the sensor unit 7 of the rotation detecting device 9 provided in the wheel bearing 50 is inserted into the outer member 51 through a sensor mounting hole 63 that is pierced in the radial direction between the rolling element rows 53 and 53. Can be attached. When the sensor target 5 is a radial type, the magnetic sensor disposed at the tip of the sensor unit 7 is opposed to the sensor target 5 via a gap in the radial direction. When the sensor target 5 is an axial type, as shown in FIG. 19, the magnetic sensor disposed at the tip of the sensor unit 7 is opposed to the sensor target 5 via a gap in the axial direction. In this case, when the sensor target 5 is, for example, the magnetic encoder of the configuration example of FIG. 15, the cylindrical portion 10 a of the back metal 10 is fitted to the inner member 52 to be concentric with the inner member 52. It is attached as follows. The sensor mounting hole 63 is a through hole having a circular cross-sectional shape, for example. The inner surface of the sensor mounting hole 63 and the sensor unit 7 are sealed with a contact seal such as an O-ring or an adhesive. Other configurations are the same as in the case of the embodiment shown in FIGS. 1 to 11 and the case of the embodiment shown in FIGS.

  In the axial torque measuring device of this embodiment, the axial torque applied to the drive shaft 1 from the torsion angle generated between the constant velocity joint 2 on the inboard side of the drive shaft 1 and the wheel bearing 50 on the outboard side. Can be requested.

1 is a longitudinal sectional view of a drive shaft and a constant velocity joint to which an axial torque measuring device for a drive shaft according to an embodiment of the present invention is applied. It is a block diagram which shows schematic structure of an axial torque measuring device. It is a block diagram which shows schematic structure of the rotation detection apparatus in a coaxial torque measuring device. It is a half front view which shows the other structural example of the sensor target in a coaxial torque measuring device. It is explanatory drawing of the example of 1 structure of the magnetic sensor in a coaxial torque measuring device. It is explanatory drawing of the other structural example of the magnetic sensor in a coaxial torque measuring device. It is a wave form diagram of the detection signal of a magnetic sensor, and the output signal of a phase difference detection means. It is a wave form diagram which shows the phase of the detection signal of each magnetic sensor, and the phase difference of both detection signals. It is a block diagram which shows the example of 1 structure of the absolute angle detection circuit of a rotation detection apparatus. It is a graph which shows the relationship between an axial torque and a twist angle. (A) is a waveform diagram showing a change in shaft torque, (B) is a waveform diagram showing a change in torsion angle. It is a block diagram which shows schematic structure of the axial torque measuring apparatus of the drive shaft in other embodiment of this invention. It is a block diagram which shows schematic structure of the rotation detection apparatus in a coaxial torque measuring device. (A) is a half sectional view showing a configuration example of a sensor target in the coaxial torque measuring device, and (B) is a perspective view of the sensor target. (A) is a half sectional view showing another configuration example of the sensor target in the coaxial torque measuring device, and (B) is a perspective view of the sensor target. It is a block diagram which shows one structural example of the multiplication circuit in a coaxial torque measuring device. It is a longitudinal cross-sectional view of the unit for wheel drive to which the shaft torque measuring apparatus of the drive shaft of this invention is applied. It is an expanded sectional view of the wheel bearing side part in the wheel bearing unit. It is an expanded sectional view showing other examples of composition of the bearing side portion for the wheel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Drive shaft 2, 3 ... Constant velocity joint 2a ... Outer ring | wheel 4 of a constant velocity joint 4, 5 ... Sensor target 4A, 4B, 5A, 5B ... Magnetic encoder 6, 7 ... Sensor unit 8, 9 ... Rotation detection apparatus 11, 11A , 11B ... magnetic sensors 11A1, 11A2 ... magnetic sensor elements 11a ... sensor elements 11AA, 11AB ... line sensors 12 ... phase difference detection means 13 ... angle calculation means 16 ... difference calculation means 17 ... data correction means 18 ... shaft torque calculation means 22 ... Mechanical play estimation means 24 ... Sensor module 25 ... Multiplication circuit 50 ... Wheel bearing 52 ... Inner member (rotary member)

Claims (12)

The outer ring of the constant-velocity joint on the differential side of the drive shaft connected to the vehicle drive system via the constant-velocity joint at both ends and the outer ring of the constant-velocity joint on the other end side of the drive shaft or via this constant-velocity joint Sensor targets are provided on the rotation side members of the wheel bearings connected to each other, and sensors for detecting the rotations of the sensor targets are provided opposite to the sensor targets. An axial torque measuring device for a drive shaft for determining axial torque,
A difference calculating means for obtaining a difference between the outputs of the sensors, and a size of mechanical play existing between members provided with the sensor targets is estimated from the difference obtained by the difference calculating means and the driving state of the vehicle. Mechanical play estimation means, data correction means for correcting the difference obtained by the difference calculation means based on the estimated value by the mechanical play estimation means, and twist of the drive shaft from the difference corrected by the data correction means only set a shaft torque calculating means for measuring the angular Request axial torque, the mechanical play estimation means estimates the period in which the operating state of the shaft torque is not applied, the twist angle of the drive shaft in the period Is statistically processed, and the appearance frequency and the appearance area are calculated. Shaft torque measuring device of the drive shaft, characterized in that it is assumed that estimates the amount of hysteresis component generated difference is fit.   2. The mechanical play estimating means according to claim 1, wherein at least one of a signal indicating a vehicle speed, an accelerator opening, a brake state, and a clutch and a speed reducer state is provided as a signal indicating a driving state of the automobile. A shaft torque measuring device for a drive shaft that is used for the estimation when a signal is input. 3. The magnetic sensor according to claim 1 , wherein each of the sensors is a magnetic sensor, and each of the sensor targets is a magnetic encoder provided concentrically with an installation member thereof, and the magnetic sensor is within a magnetic pole pitch of the magnetic encoder. A shaft of a drive shaft having a plurality of sensor elements arranged at positions shifted from each other and capable of obtaining a signal output of two phases of sin and cos and detecting the position by multiplying the position in the magnetic pole Torque measuring device. 3. The magnetic sensor according to claim 1 , wherein each of the sensors is a magnetic sensor, and each of the sensor targets is a magnetic encoder provided concentrically with an installation member thereof. A shaft torque measuring device for a drive shaft, which is composed of line sensors having sensor elements arranged along the line, and generates a two-phase signal output of sin and cos by calculation and multiplies and detects the position in the magnetic pole. 3. The drive shaft axial torque measuring device according to claim 1 , wherein each of the sensors detects an absolute rotation angle of the sensor target. 6. The sensor target according to claim 5 , wherein each of the sensor targets includes a plurality of magnetic encoders provided concentrically with the installation member and having different numbers of magnetic poles, and each of the sensors detects a plurality of magnetic fields of the plurality of magnetic encoders. Each of these magnetic sensors has a function of detecting position information in the magnetic pole of the magnetic encoder, and a phase difference detecting means for obtaining a phase difference of the magnetic field signal detected by each magnetic sensor; A drive shaft axial torque measuring device comprising: an angle calculating means for calculating an absolute rotation angle of the sensor target based on the detected phase difference. 7. The magnetic sensor according to claim 6 , wherein the magnetic sensor is constituted by a line sensor in which sensor elements are arranged along an arrangement direction of magnetic poles of the magnetic encoder, and generates a two-phase signal output of sin and cos by calculation, A shaft torque measuring device for a drive shaft that detects the position by multiplying it. 8. The shaft torque measuring device for a drive shaft according to claim 6 , wherein the magnetic sensor, the phase difference detecting means, and the angle calculating means of each sensor are integrated into a sensor module. 9. The drive shaft axial torque measuring device according to claim 8 , wherein the sensor module is integrated on a semiconductor chip. A drive shaft with an axial torque measuring device, wherein the axial torque measuring device according to any one of claims 1 to 9 is mounted on the drive shaft. A wheel driving unit with an axial torque measuring device, wherein the shaft torque measuring device according to any one of claims 1 to 9 is mounted on a wheel driving unit including a wheel bearing and a drive shaft. The outer ring of the constant-velocity joint on the differential side of the drive shaft connected to the vehicle drive system via the constant-velocity joint at both ends and the outer ring of the constant-velocity joint on the other end side of the drive shaft or via this constant-velocity joint Sensor targets are provided on the rotation side members of the wheel bearings connected to each other, and sensors for detecting the rotations of the sensor targets are provided opposite to the sensor targets. A method for measuring shaft torque of a drive shaft to obtain shaft torque,
The difference between the outputs of the sensors is obtained, and the magnitude of mechanical play existing between the members provided with the sensor targets is estimated from the difference and the driving state of the vehicle. correcting the difference between the output of the sensor, it determined Me a shaft torque by measuring the twist angle of the drive shaft from the corrected difference, as the magnitude of the mechanical play, the operating state of the shaft torque is not applied Hysteresis component that occurs in the difference in the output of each sensor due to mechanical play by estimating a certain period, statistically processing the distribution of the torsion angle of the drive shaft during that period, and calculating its appearance frequency and appearance area A method for measuring an axial torque of a drive shaft, wherein the size of the drive shaft is estimated .

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