JP2009092400A - Device and method for measuring axial torque of drive shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for measuring axial torque of a drive shaft which enable accurate detection of the axial torque even when one end side of the drive shaft is in a state of stoppage or when the speed of rotation thereof is extremely low. <P>SOLUTION: A sensor target is provided in the outer ring of each isokinetic joint of the drive shaft connected to a driving system of an automobile by the medium of the isokinetic joints at the opposite ends. A sensor for detecting rotation of each sensor target is provided opposite to each sensor target and the axial torque of the drive shaft is determined by comparing outputs of the sensors with each other. Each sensor has a magnetometric sensor which detects directly the rotation of each sensor target opposite thereto and a multiply circuit which multiplies a rotation signal outputted by the magnetometric sensor and forms a rotation pulse of high resolution. A rotation pulse difference calculating means 13 which counts the rotation pulse formed by the multiply circuit of each sensor and determines the difference between counted values is provided. An axial torque operation means 17 which measures the amount of torsion of the drive shaft from the difference and determines the axial torque is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

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, and a drive shaft equipped with the shaft torque measuring device. 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 shaft of the drive shaft for attaching a pulsar ring to each constant velocity joint, that is, an outer ring of each constant velocity joint on the inboard side and the outboard side. A torque measurement method is shown. That is, the rotation signal generated by both pulsar rings is detected, and the phase difference of the rotation signal corresponding to the torsion generated in the drive shaft is calculated to determine the shaft torque.
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.

  In Patent Document 2, in the above-described shaft torque measurement method, the phase difference between the rotation pulse signal on the outboard side and the rotation pulse signal on the inboard side is calculated as the maximum difference of the drive shaft as the calculation process of the phase difference of the rotation signal. What is calculated | required as a phase difference detection pulse number which is a count value of the constant frequency pulse which has a frequency more than the rotation pulse frequency in rotation speed is disclosed.

  Patent Document 3 discloses a method of generating and counting a reference pulse having a frequency synchronized with the rotational speed in the same manner as in Patent Document 2.

  Patent Document 4 discloses a method using a rotation detection sensor and two separately provided sensor targets in the same manner as in Patent Document 2.

Moreover, in patent document 5, while providing a sensor target in the outer ring | wheel of each constant velocity joint of a drive shaft, the sensor which detects rotation of each sensor target is provided facing each of these sensor targets, and the output of these sensors is provided. What calculates | requires the axial torque of a drive shaft by comparison is disclosed.
Japanese Unexamined Patent Publication No. 7-63628 JP 2007-93406 A JP 2007-93407 A JP 2007-93452 A JP 2007-163432 A

In the techniques disclosed in Patent Documents 1 to 4, a sensor that outputs a rotation pulse is used, and the amount of twist is detected by calculating a phase shift in the rotation pulse output at both ends of the drive shaft. However, in this case, there is a problem that the shaft torque cannot be accurately detected when one shaft end is in a stopped state or when the rotational speed is extremely low, such as when driving is started from a stopped state.
In Patent Document 5, the sensor format is not specified. However, in the embodiment, an example in which the phase difference between output pulses is detected as a time difference is presented. In this case, unless both ends of the shaft rotate to generate a pulse, the amount of twist of the drive shaft cannot be measured.

  An object of the present invention is to provide an axial torque measurement device for a drive shaft, a drive shaft with an axial torque measurement device, and a drive shaft capable of accurately detecting an axial torque even when one end of the drive shaft is stopped or extremely low in rotational speed. It is to provide a method for measuring shaft torque.

The drive shaft axial torque measuring device according to the present invention is provided with sensor targets on the outer rings of the respective constant velocity joints of the drive shaft connected to the drive system of the automobile via the constant velocity joints at both ends. Oppositely, a sensor for detecting the rotation of each sensor target is provided, and the shaft torque of the drive shaft is obtained by comparing the outputs of these sensors. The sensors directly detect the rotation of the opposing sensor targets. A magnetic sensor to detect and a multiplication circuit that multiplies a rotation signal output from the magnetic sensor to generate a high-resolution rotation pulse, and counts the rotation pulses generated by the multiplication circuit of each sensor, Rotation pulse difference calculating means for obtaining a difference between these count values, and twist of the drive shaft from the difference Characterized by providing an axial torque calculating means for calculating a shaft torque by measuring.
According to this configuration, since the minute torsion angle of the drive shaft can be detected with high resolution, the shaft torque can be accurately detected, and vehicle travel control that supplies the optimum applied torque to the tire is also possible. In addition, since the shaft torque is calculated by counting the rotation pulses, even if one of the two sensor targets is stopped, that is, even when one end of the drive shaft is stopped or the rotation speed is extremely low, it is accurate. The shaft torque can be detected.

  In this invention, the sensor target is a magnetic encoder provided in a ring shape concentric with the outer ring of the constant velocity joint, and the magnetic sensors are arranged at a plurality of positions shifted from each other within the magnetic pole pitch of the magnetic encoder. Even if the rotation pulse generated by the multiplier circuit is detected by multiplying the position in the magnetic pole, the sensor circuit can obtain a two-phase signal output of sin and cos. good. In the case of this configuration, the position in the magnetic pole of the magnetic encoder can be detected more finely, and a rotation pulse with higher resolution can be generated.

  In this invention, the sensor target is a magnetic encoder provided in a ring shape concentric with the outer ring of the constant velocity joint, and the magnetic sensor is a line sensor in which sensor elements are arranged along the arrangement direction of the magnetic poles of the magnetic encoder The rotation pulse generated by the multiplication circuit may be detected by multiplying the position in the magnetic pole. . 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 rotation pulse generated by any one of the multiplication circuits of the sensors may be two pulse signals of A phase and B phase having a phase difference of 90 ° from each other. In this configuration, the rotational direction can be determined from these two-phase signals, so that 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.

In this invention, the steady offset amount included in the shaft torque obtained by the shaft torque calculating means is estimated from the difference between the rotation pulses obtained by the rotation pulse difference calculating means and the predetermined data indicating the operating state. An offset canceling means for canceling the offset from the shaft torque may be provided.
When each rotation pulse is counted with a counter and the current rotation angle of the drive shaft is held as a count value, a steady offset occurs in the count value due to mechanical backlash, or the count values of both counters due to erroneous counting due to noise May cause an error in the calculation of the shaft torque. The offset canceling means extracts the steady offset by performing filter processing according to the data relating to the operating state (acceleration / deceleration state, engine speed, etc.) while monitoring the torque output value of the shaft torque calculating means, that is, the angle difference. If the offset is canceled in the calculation processing by the shaft torque calculation means, the influence of the offset caused by mechanical play or the like can be reduced, and an accurate shaft torque can be detected.

  In this invention, you may provide the count value reset means which resets the count value which the said rotation pulse difference calculation means counts in the driving | running state in which the shaft torque is not applied. In the case of this configuration, it is possible to detect an accurate shaft torque by removing the influence of noise accumulated on the count value.

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, since the minute torsion angle of the drive shaft can be detected with high resolution, the shaft torque can be accurately detected, and vehicle travel control that supplies the optimum applied torque to the tire is also possible. This makes it possible to reduce the weight of the drive shaft.

The shaft torque measurement method for a drive shaft according to the present invention provides a sensor target on the outer ring of each constant velocity joint of a drive shaft connected to the drive system of an automobile via a constant velocity joint at both ends, and faces each of these sensor targets. A method for measuring the shaft torque of the drive shaft by detecting the rotation of each sensor target with a sensor provided and determining the shaft torque of the drive shaft by comparing the output of these sensors, wherein the rotation detection of each sensor target by the respective sensors is detected. Is a device that directly detects the rotation of each of the sensor targets facing each other with a magnetic sensor, multiplies the rotation signal output from the magnetic sensor with a multiplication circuit, and generates a high-resolution rotation pulse. The rotation pulses generated by the And obtaining the shaft torque by measuring the amount of twist shaft.
According to this axial torque measuring method, a minute torsion angle of the drive shaft can be detected with high resolution, the axial torque can be accurately detected, and vehicle traveling control can be performed such that the optimum applied torque is supplied to the tire. In addition, because of the detection method that counts the rotation pulses, even if one of the two sensor targets is stopped, that is, for example, when one end of the drive shaft is stopped or the rotation speed is extremely low, the shaft torque is accurately detected. it can.

The drive shaft axial torque measuring device according to the present invention is provided with sensor targets on the outer rings of the respective constant velocity joints of the drive shaft connected to the drive system of the automobile via the constant velocity joints at both ends. Oppositely, a sensor for detecting the rotation of each sensor target is provided, and an axial torque measuring device for a drive shaft that obtains the axial torque of the drive shaft by comparing the outputs of these sensors. A magnetic sensor that directly detects the rotation of the sensor target, and a multiplication circuit that multiplies the rotation signal output from the magnetic sensor to generate a high-resolution rotation pulse, and the rotation generated by the multiplication circuit of each sensor. Rotation pulse difference calculation means for counting pulses and obtaining a difference between these count values; Due to the provision of a shaft torque calculating means for measuring the amount of twist the drive shaft seek shaft torque from, even if one end of the drive shaft is stopped or extremely low rotational speed can be detected accurately axial torque.
Since the drive shaft with an axial torque measuring device of the present invention is equipped with the axial torque measuring device of the present invention on the drive shaft, a minute torsion angle of the drive shaft can be detected with high resolution, and the axial torque can be accurately detected. In addition, it is possible to perform vehicle travel control in which an optimum applied torque is supplied to the tire, which makes it possible to reduce the weight of the drive shaft.
The shaft torque measurement method for a drive shaft according to the present invention provides a sensor target on the outer ring of each constant velocity joint of a drive shaft connected to the drive system of an automobile via a constant velocity joint at both ends, and faces each of these sensor targets. A method for measuring the shaft torque of the drive shaft by detecting the rotation of each sensor target with a sensor provided and determining the shaft torque of the drive shaft by comparing the output of these sensors, wherein the rotation detection of each sensor target by the respective sensors is detected. Is a device that directly detects the rotation of each of the sensor targets facing each other with a magnetic sensor, multiplies the rotation signal output from the magnetic sensor with a multiplication circuit, and generates a high-resolution rotation pulse. The rotation pulses generated by the Since the shaft torque is obtained by measuring the amount of shaft torsion, the minute torsion angle of the drive shaft can be detected with high resolution, the shaft torque can be accurately detected, and the optimum applied torque is supplied to the tire. Vehicle driving control is also possible. Further, because of the detection method for counting the rotation pulses, the shaft torque can be detected accurately even if one of the two sensor targets is stopped.

  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 the case of the illustrated embodiment, the inboard side is connected to a differential (not shown) by a tripod type slide type constant velocity joint 2, and the outboard side is connected to a differential (not shown) by a barfield type fixed type constant velocity joint 3. Concatenated with

  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 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 side, sensor-side units 6 and 7 including magnetic sensors 11 (FIG. 3) and the like are installed at positions close to the sensor targets 4 and 5, and when the sensor targets 4 and 5 rotate, the sensor-side unit 6 , 7 outputs a rotation signal having a frequency proportional to the rotation speed. Corresponding angle sensor targets 4 and 5 and sensor side units 6 and 7 constitute rotation detectors 8 and 9 for detecting a rotation speed and a rotation angle, respectively.

  The sensor targets 4 and 5 have, for example, a plurality of magnetic pole pairs 4a (5a) arranged at equal positions in the circumferential direction of the peripheral surface, as shown in a half sectional view and a perspective view in FIGS. It consists of a ring-shaped magnetic encoder magnetized side by side, and is attached so as to be concentric with the constant velocity joint outer ring 2a (3a). In this case, the magnetic sensor 11 is arranged on the outer diameter side so as to face the peripheral surface of the magnetic encoder 5 so that the magnetic poles N and S of the magnetic encoders 4 and 5 can be directly detected.

The configuration example of the magnetic encoders 4 and 5 in FIG. 4 is a radial type in which a magnetic pole pair 4a (5a) is magnetized on the peripheral surface, but the magnetic encoders 4 and 5 are half of the configuration shown in FIGS. It may be an axial type shown in a partial sectional view and a perspective view. In the configuration example of FIG. 5, for example, a plurality of magnetic pole pairs 4a (5a) are 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. ) Are arranged at equal positions and magnetized, and the cylindrical portion 10a of the back metal 10 is fitted to the constant velocity joint outer ring 2a (3a), thereby being concentric with the constant velocity joint outer ring 2a (3a). It is attached to become. In this case, the magnetic sensor 11 is arranged in the axial direction so as to face the magnetized surfaces of the 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. 2 shows a schematic configuration of the drive shaft axial torque measuring apparatus, and FIG. 3 shows a schematic configuration of the rotation detectors 8 and 9 described above. As described above, the rotation detectors 8 and 9 include the sensor targets 4 and 5 and the sensor side units 6 and 7 disposed to face the sensor targets 4 and 5. The sensor-side units 6 and 7 include a magnetic sensor 11 that directly detects the rotation of the opposing sensor targets 4 and 5, and a multiplication circuit that multiplies a rotation signal output from the magnetic sensor 11 to generate a high-resolution rotation pulse. Twelve.

The magnetic sensor 11 has a function capable of detecting a magnetic pole with higher resolution than the magnetic pole pairs 4a and 5a of the corresponding sensor targets (magnetic encoders) 4 and 5, that is, detects position information within the magnetic pole range of the magnetic encoders 4 and 5. It is assumed to have a function. In order to satisfy this function, for example, the magnetic sensor 11 may be configured as shown in FIG. 6 when the pitch λ of one magnetic pole pair 4a (5a) of the corresponding magnetic encoder 4, 5 is one cycle. That is, two magnetic sensor elements 11A and 11B such as Hall elements arranged apart from each other in the magnetic pole arrangement direction so as to have a phase difference of 90 degrees (λ / 4) are used, and these two magnetic sensor elements 11A and 11B are used. The phase in the magnetic pole (φ = tan ⁻¹ (sinφ / cosφ)) may be multiplied from the two-phase signal (sinφ, cosφ) to be calculated. The waveform diagram of FIG. 6 shows the arrangement of the magnetic poles of the magnetic encoders 4 and 5 in terms of magnetic field strength. In this case, the multiplication circuit 12 in FIG. 3 outputs a rotation pulse as multiplication position information in the magnetic pole.

  When the magnetic sensor 11 has such a configuration, the position in the magnetic pole can be detected more finely, and the phases of the magnetic encoders 4 and 5 can be detected with higher accuracy. In this case, in order to reduce the influence of magnetic noise, the two magnetic sensor elements 11A and 11B may have a differential configuration so as to obtain a more stable signal.

  As another example of the magnetic sensor 11 having a function of detecting position information in the magnetic poles of the magnetic encoders 4 and 5, a line sensor as shown in FIG. 7B may be used. That is, as the magnetic sensor 11, 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 4 and 5 are used. FIG. 7A is a waveform diagram in which one magnetic pole section in the magnetic encoders 4 and 5 is converted into a magnetic field strength. In this case, the first line sensor 11AA of the magnetic sensor 11 is arranged in association with the 90-degree phase section of the 180-degree phase section in FIG. 7A, 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. 7C is obtained. In addition, 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 two-phase output signals sin and cos obtained in this way are processed by, for example, the multiplication circuit 12 having the configuration shown in FIG. 8 to obtain a rotation pulse as multiplication position information in the magnetic pole.

  When the magnetic sensor 11 is constituted by a line sensor in this way, the influence of the distortion and noise of the magnetic field pattern is reduced, and the phases of the magnetic encoders 4 and 5 can be detected with higher accuracy. In this case, even if the magnetic encoders 4 and 5 having a sufficiently large magnetic pole pitch are used, the phase of the magnetic encoders 4 and 5 can be detected with a resolution of several to several tens of times. The twist angle of the drive shaft 1 can also be detected.

In this case, the multiplication circuit 12 of FIG. 8 includes a signal generating means 41, a fan-shaped detecting means 42, a multiplexer means 43, and a fine interpolation means 44.
The signal generator 41 has the same amplitude A ₀ and the same average value C ₀ from the two-phase signal sin, cos that is the output of the magnetic sensor 11, and m is a positive integer less than n, i as 1 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 is ^m digital signals b _{n−m + 1} , b _{n−m + 2} ,..., B _n−1 encoded so as to define 2 ^m equal sector P _i. , B _n are generated by detecting 2 ^m sectors P _i divided by 2 ^m−1 signals si.
The multiplexer means 43 is controlled by the m digital signals b _{n-m + 1} , b _{n-m + 2} ,..., B _n−1 , b _n generated from the sector generating means 42, 2 ^m-1 signals si generated from means 41 To process the above signal si with a series of 2 ^m-1 amplitudes. One signal A constituted by a portion between the average value C ₀ and the first threshold value L _1, and a series of 2 ^{m -1} signals si Analog means for generating the other signal B constituted by a portion between the first threshold value L ₁ and the second threshold value L ₂ higher than this threshold value.
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 To generate (n−m) digital signals b ₁ , b ₂ ,..., B _nm−1 , b _nm in each of the 2 ^m sectors P _i , the multiplexer means 43. Is a means for finely interpolating the one signal A and the other signal B generated from.
This multiplier circuit 12, signal sin a 2 phase obtained by the magnetic sensor 11, cos is the multiplied signal (nm) number of digital signal _{b 1, b 2, ......,} b nm-1, b It is multiplied by a rotation pulse of _nm (here b ₁ , b ₂ ,..., b ₈ , b ₉ ).

  In the configuration of FIG. 2, the rotation pulse difference calculation means 13 is means for counting the rotation pulses generated by the multiplication circuit 12 of each of the sensor side units 6 and 7, and obtaining the difference between these count values. The rotation pulse difference calculation means 13 includes a first counter 14 that counts rotation pulses generated by the multiplication circuit 12 on the one rotation detector 8 side, and a rotation generated by the multiplication circuit 12 on the other rotation detector 9 side. A second counter 15 for counting pulses and an angle difference calculating means 16 for calculating the difference between the count values of the counters 14 and 15 are provided.

  The shaft torque calculating means 17 is a means for measuring the twist amount of the drive shaft 1 from the difference obtained by the rotation pulse difference calculating means 16 and calculating the shaft torque from the twist amount.

The output circuit 18 is a means for outputting the shaft torque obtained by the shaft torque calculating means 17 to the outside.
The controller 19 includes an offset cancel unit 20 and a count value reset unit 21. The offset canceling means 20 is obtained by the shaft torque calculating means 17 from the rotation pulse difference obtained by the rotation pulse difference calculating means 13 and predetermined data indicating the driving state sent from the control unit of the automobile. This is a means for canceling the steady offset included in the shaft torque. The count value resetting means 21 is a means for resetting the count values counted by the counters 14 and 15 in the rotation pulse difference calculating means 13 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.
When a vehicle starts suddenly and accelerates, the shaft torque generated in the drive system is large, and the drive shaft has the lowest rigidity excluding the clutch portion in the drive systems of four and two-wheeled vehicles. Therefore, the drive shaft 1 is twisted. The torsion angle is calculated based on the rotation pulses from the sensor side units 6 and 7 including the magnetic sensor 11 and the like, and the shaft torque is obtained.

  Specifically, in each of the rotation detectors 8 and 9 in FIG. 2, the rotation position of each sensor target 4 and 5 is detected by the magnetic sensor 11 as shown in FIG. 3, and the rotation signal output by the magnetic sensor 11 is output. Multiplication is performed by the multiplication circuit 12 to generate a high-resolution rotation pulse. That is, in the case of this embodiment in which the sensor targets 4 and 5 are magnetic encoders, the sensor-side units 6 and 7 (FIG. 3) including the magnetic sensor 11 and the multiplier circuit 12 have the number of magnetic poles of the magnetic encoders 4 and 5. A multiplication function for generating a rotation pulse of double to several tens of times is provided. Thereby, the rotation of the drive shaft 1 can be detected with high resolution. In this case, it is possible to detect rotation with high resolution several times to several tens of times the number of magnetic poles while keeping the magnetic pole pitch of the magnetic encoders 4 and 5 equal to that of a normal ABS sensor. While maintaining the same level as before, high resolution can be obtained even in harsh usage environments such as automobiles. Accordingly, even a slight rotational deviation can be detected, and a minute shaft torque can be detected from the difference in rotational angle detected by both sensor side units 6 and 7.

  Of the multiplication circuits 12 of the sensor side units 6 and 7, the rotation pulse generated by any one of the multiplication circuits 12 may be two A-phase and B-phase pulse signals whose phases are different from each other by 90 °. In this case, since the rotation direction can be determined 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 14 and 15, respectively, and are 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 14 and 15. The shaft torque calculation means 17 measures the twist amount of the drive shaft 1 from the calculated difference value of the rotation pulses, and calculates the shaft torque corresponding to the twist amount according to 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 calculated by calculating from the rotation pulses output from the rotation detectors 8 and 9, it is impossible with the method of detecting the signal phase difference described above as a conventional example. It is also possible to detect the shaft torque when one of them is stopped.

  The sensor-side units 6 and 7 of the two rotation detectors 8 and 9 may have different resolutions. In this case, since the two counters 14 and 15 in FIG. 2 change at different speeds, before obtaining the difference between the respective count values, each count 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 a count value, a steady offset occurs in the count value due to mechanical play, or the counters 14 and 14 are erroneously counted due to noise. The count value of 15 may shift and an error may occur in the shaft torque calculation. Therefore, in this embodiment, the offset canceling means 20 in the controller 19 monitors the torque output value of the shaft torque calculating means 17, that is, the angle difference, and the data (acceleration / deceleration state) separately given from the vehicle travel control device, for example. The stationary offset is extracted by performing filter processing according to engine speed, etc., and the offset is removed in the calculation processing by the shaft torque calculation means 17. Thereby, it is possible to detect an accurate shaft torque by reducing the influence of an offset caused by mechanical play or the like.

  Further, in this embodiment, the count value canceling means 21 in the controller 19 performs a process of periodically resetting the counters 14 and 15 at the timing of the operation state where no shaft torque is applied. In addition, the erroneous count value accumulated in the counters 14 and 15 may be reset. As a result, the influence of noise accumulated in the counters 14 and 15 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 21.

  As described above, according to the shaft torque measurement method of the drive shaft, since the minute torsion angle of the drive shaft 1 can be detected with high resolution, the shaft torque can be detected accurately and the optimum applied torque is supplied to the tire. Vehicle travel control is also possible. 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 5 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.

It is a longitudinal cross-sectional view of the drive shaft and constant velocity joint which apply the axial torque measuring device concerning one Embodiment of this invention. It is a block diagram which shows schematic structure of a coaxial torque measuring device. It is a block diagram which shows schematic structure of the rotation detector 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 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 block diagram which shows one structural example of the multiplication circuit in a coaxial torque measuring device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Drive shaft 2, 3 ... Constant velocity joint 2a, 3a ... Outer ring | wheel 4 of a constant velocity joint, 5 ... Sensor target 6, 7 ... Sensor side unit 8, 9 ... Rotation detector 11 ... Magnetic sensor 11A, 11B ... Magnetic sensor Element 11a ... Sensor elements 11AA, 11AB ... Line sensor 12 ... Multiplication circuit 13 ... Rotation pulse difference calculating means 17 ... Axial torque calculating means 20 ... Offset canceling means 21 ... Count value resetting means

Claims (8)

A sensor target is provided on the outer ring of each constant velocity joint of the drive shaft connected to the drive system of the vehicle via a constant velocity joint at both ends, and the rotation of each sensor target is detected opposite to each sensor target. A shaft torque measuring device for a drive shaft that provides sensors and obtains the shaft torque of the drive shaft by comparing the outputs of these sensors,
Each of the sensors includes a magnetic sensor that directly detects the rotation of each of the opposing sensor targets, and a multiplication circuit that multiplies a rotation signal output from the magnetic sensor to generate a high-resolution rotation pulse. Rotation pulse difference calculating means for calculating the difference between these counted values by counting the rotation pulses generated by the multiplication circuit of each sensor, and shaft torque calculating means for determining the shaft torque by measuring the twist amount of the drive shaft from the difference A shaft torque measuring device for a drive shaft, characterized in that   2. The magnetic encoder according to claim 1, wherein the sensor target is a magnetic encoder provided in a ring shape concentric with an outer ring of the constant velocity joint, and the magnetic sensors are arranged at positions shifted from each other within a magnetic pole pitch of the magnetic encoder. A drive having a plurality of sensor elements and capable of obtaining a two-phase signal output of sin and cos, wherein the rotation pulse generated by the multiplication circuit is detected by multiplying the position in the magnetic pole Shaft torque measuring device.   2. The line according to claim 1, wherein the sensor target is a magnetic encoder provided in a ring shape concentric with an outer ring of the constant velocity joint, and the magnetic sensor is a line in which sensor elements are arranged along an arrangement direction of magnetic poles of the magnetic encoder. A drive shaft that is constituted by a sensor and generates a two-phase signal output of sin and cos by calculation, and the rotation pulse generated by the multiplier circuit is detected by multiplying the position in the magnetic pole. Shaft torque measuring device.   4. The rotation pulse generated by any one of the multiplication circuits of the sensors according to claim 1, wherein the rotation pulses generated by the multiplication circuit are two pulses of an A phase and a B phase that are 90 ° out of phase with each other. A shaft torque measuring device for the drive shaft that is a signal   5. The shaft torque obtained by the shaft torque calculating means according to claim 1, based on the difference between the rotation pulses obtained by the rotation pulse difference calculating means and predetermined data indicating an operating state. A shaft torque measuring device for a drive shaft provided with offset canceling means for estimating a steady offset amount included in the shaft torque and canceling the offset from the shaft torque.   6. The shaft of the drive shaft according to claim 1, further comprising: a count value resetting unit that resets a count value counted by the rotation pulse difference calculating unit in an operating state in which no shaft torque is applied. Torque measuring device.   A drive shaft with an axial torque measuring device, wherein the axial torque measuring device according to any one of claims 1 to 6 is mounted on the drive shaft. A sensor target is provided on the outer ring of each constant velocity joint of the drive shaft that is connected to the drive system of the vehicle via a constant velocity joint at both ends, and each sensor target is rotated by a sensor provided opposite to each sensor target. A shaft torque measurement method for a drive shaft that detects and determines the shaft torque of the drive shaft by comparing the outputs of these sensors,
The rotation detection of each sensor target by each sensor detects the rotation of each opposing sensor target directly by a magnetic sensor, and the rotation signal output from this magnetic sensor is multiplied by a multiplication circuit to generate a high-resolution rotation pulse. The rotation pulse generated by the multiplication circuit of each sensor is counted, the difference between these count values is obtained, and the torsion amount of the drive shaft is measured from the difference to obtain the shaft torque. A method for measuring the shaft torque of a drive shaft.

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