JP2007093407A - Method and instrument for measuring shaft torque of drive shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an instrument for measuring shaft torque, capable of accurately measuring the shaft torque acting on a drive shaft. <P>SOLUTION: Sensor targets 4, 5 are attached to outer rings 2a, 2b of respective constant-velocity universal joints 2, 3, rotation signals generated by the both sensor targets 4, 5 are detected by sensors 6, 7, and a phase difference between the rotation signals corresponding to a torsion generated in the drive shaft 1 is subjected to computation processing to find the shaft torque. In the computation processing of the phase difference, the rotational speed of the drive shaft 1 is detected to generate a pulse of frequency proportional to the detected rotational speed, the phase difference between the rotation pulse in an outboard side and the rotation pulse on the inboard side is found as the counted value of the pulse proportional to the rotation speed. The pulse proportional to the rotational speed is set as ä60× the rotational speed of drive shaft(rpm)/S}Hz or higher, where S represents the resolution in the detection of the torsion angle of the drive shaft 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for measuring a shaft torque of a drive wheel axle having a role of transmitting the power of an automobile engine to a wheel, that is, a drive shaft. As such a drive shaft, a front 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 type suspension, 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). Yes. For this purpose, 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 with the rotation of the wheel, it approaches it. Thus, a pulse having a frequency proportional to the wheel speed 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 by reducing the excessive shaft torque, the shaft diameter of the drive shaft and the constant velocity joint are reduced in weight. It is disclosed.
Japanese Unexamined Patent Publication No. 7-63628

A constant velocity joint of a drive shaft used in an automobile is required to have a strength sufficient to withstand an excessive torque generated when the automobile is suddenly started or accelerated. Therefore, the shaft diameter and joint outer diameter are large, and the weight must be heavy.
On the other hand, weight reduction of the vehicle body is very effective for improving fuel efficiency, and the drive shaft is also required to be light weight.

In order to reduce the weight, it is necessary to accurately measure the shaft torque acting on the drive shaft and control the engine output with the obtained shaft torque to prevent the generation of excessive torque, as disclosed in Patent Document 1. It is effective.
However, Patent Document 1 discloses a method for obtaining the shaft torque of the drive shaft based on the phase difference between the constant velocity joints on both sides as described above, but there is no specific description for measuring the phase difference, and it is accurate. It has been desired to establish a method for measuring the correct torque.

  Also, when traveling on a low μ (coefficient of friction) road, tire slip is likely to occur, and if the road surface-tire acting force in the tire traveling direction can be measured, this measurement data is used to control this in advance by vehicle body control. It is also possible to prevent this. Therefore, establishment of a method capable of measuring the road surface-tire acting force is also desired.

  The object of the present invention is to accurately measure the axial torque acting on the drive shaft, contribute to reducing the weight of the drive shaft, and further to estimate the acting force between the road surface and the tire. It is to provide a method and a measuring device.

The shaft torque measurement method for a drive shaft according to the present invention is such that a sensor target is attached to 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 is opposed to the sensor target. Rotation pulse signals generated by detecting both sensor targets with the provided sensor are detected, and the phase difference of the rotation signal corresponding to the torsion generated in the drive shaft is calculated from the detected rotation pulse signal to calculate the shaft torque. In this method, the following process is performed as the phase difference calculation process.
That is, in the phase difference calculation process, the rotation speed of the drive shaft is detected by the rotation pulse signal on the outboard side, the rotation pulse signal on the inboard side, or an external rotation sensor, and the detected rotation speed of the drive shaft is calculated. A pulse having a proportional frequency is generated, and a phase difference between the rotation pulse on the outboard side and the rotation pulse on the inboard side is obtained as a count value of the rotation number proportional pulse.
The frequency of the rotation speed proportional pulse is set to (60 × drive shaft rotation speed (rpm) / S) Hz or more when the resolution of detection of the twist angle of the drive shaft is S degrees.

If a sensor target is attached to the outer ring of each constant velocity joint at both ends of the drive shaft and a sensor is attached opposite to this sensor target, when the drive shaft is twisted by torque, the twist is a rotation signal generated by both sensor targets. Appears as a phase difference.
In this phase difference calculation process, a rotation speed proportional pulse having a frequency proportional to the rotation speed of the drive shaft is generated, and the phase difference between the rotation pulse signal on the outboard side and the rotation pulse signal on the inboard side is determined by the rotation speed. Calculate by the count value of proportional pulse. By using the rotation-proportional pulse in consideration of the measurement resolution, that is, the resolution for detecting the twist angle of the drive shaft as described above, the twist angle can be accurately detected.
In this way, the phase difference of the rotation signal corresponding to the twist generated in the drive shaft can be accurately obtained, and the shaft torque is obtained by calculating this phase difference.

By controlling the output of the engine based on the obtained shaft torque signal and suppressing the occurrence of excessive torque, the constant velocity joint can be reduced in size and weight.
By measuring the axial torque, it is possible to estimate the road surface-tire acting force in the tire traveling direction. When driving on low μ roads, tire slip is likely to occur, but if the road surface-tire acting force in the tire traveling direction can be measured, this measurement data can be used to prevent this beforehand by vehicle body control. It becomes possible.

  As the rotation detector composed of the sensor target and the sensor opposed to the sensor target, one provided in one constant velocity joint for ABS control may be used. In that case, a rotation detector similar to the other constant velocity joint may be used. Is good.

In the method of the present invention, the sensor target has a plurality of teeth or pole pairs equally arranged in the circumferential direction, the number of the teeth or pole pairs is A, and the maximum twist angle to be measured is Bdeg.
B> (180 / A)
It may be.
In this way, by restricting the relationship between the number A of teeth or pole pairs and the maximum twist angle B to be measured, erroneous counting of the number of phase difference detection pulses is avoided, the calculation method for estimating the twist is simplified, and the shaft Increases the reliability of torque detection.

The sensor target is fixed to the outer ring of the constant velocity joint so that the phase difference between the rotation pulse signal on the outboard side and the rotation pulse signal on the inboard side is zero when no torque is applied to the drive shaft. Alternatively, the phase angle of the sensor may be set.
Thereby, it can be avoided that the phase difference is detected in a state where no torque is applied to the drive shaft.

Further, the phase difference between the rotation pulse signal on the outboard side of the drive shaft and the rotation pulse signal on the inboard side of the drive shaft in a state in which no torque is applied to the drive shaft is obtained. The calculation result of the phase difference may be corrected.
This correction improves the accuracy and reliability of shaft torque detection.

  In the method of the present invention, before detecting each rotation pulse signal, the relationship between the torque between the outer rings of both constant velocity joints and the phase difference is obtained in advance by measurement or calculation, and the obtained torque The phase difference calculation result at the time of measuring the shaft torque may be corrected based on the relationship between the phase difference and the phase difference. This makes it possible to measure the shaft torque more accurately.

When the twist angle of the drive shaft corresponding to the measured shaft torque of the drive shaft is equal to or larger than the set maximum twist angle Bdeg, an abnormal signal may be output to the outside.
As a result, the reliability of shaft torque detection can be further improved, and at the same time, damage to the drive shaft 1 can be prevented.

Alternatively, a plurality of sensors installed opposite to each sensor target may be used, and the plurality of sensors may be fixed at a predetermined interval.
In this case, the rotation direction of the drive shaft is detected from the output of the sensor facing the same sensor target, or the rotation direction of the drive shaft is detected by an external sensor, and the detection result of the rotation direction is used as a basis. In addition, the calculation formula of the phase difference at the time of measuring the shaft torque may be changed.

In the present invention, each sensor target has a plurality of teeth or magnetic pole pairs equally arranged in the circumferential direction, and the thickness of the tooth of the sensor target and the width between adjacent teeth, or the pole pair When the width of the poles and the distance between the poles are substantially the same, a plurality of sensors are arranged opposite to each sensor target, and the outputs of the plurality of sensors are D (180 / D) deg. The output of these sensors divides the pulse output due to unevenness or pole change due to the dentition of the sensor target into D parts, and uses this D-divided pulse output as a control signal for the anti-lock brake system You may do it.
Thereby, the resolution of rotation detection can be improved and rotation detection accuracy comparable to the rotation detection device provided in the wheel bearing can be obtained.

In this case, the position of each sensor may be set so that the outputs of the D sensors placed facing each sensor target have a phase difference of (180 / D) deg.
Further, in this case, the measurement results of the sensor outputs facing both sensor targets in advance so that the outputs of the D sensors installed facing the sensor targets have a phase difference of (180 / D) deg. Then, the phase difference may be detected and stored, and the sensor output may be corrected based on the stored detection value and the rotation speed of the sensor target.
Thereby, the precision as a control sensor of the anti-lock brake system can be improved.

  The vehicle travel control method of the present invention is characterized in that the shaft torque signal obtained by the shaft torque measurement method for a drive shaft having any one of the above configurations of the present invention is used for vehicle travel control.

The shaft torque measuring device for a drive shaft according to the present invention is provided at each end of each constant velocity joint (2, 3) of the drive shaft (1) connected to the drive system of the automobile via the constant velocity joint (2, 3) at both ends. A sensor target (4, 5) is attached to the outer ring, and a sensor (6, 6) that detects a rotation pulse signal generated by detecting each sensor target (4, 5) facing the sensor target (4, 5). 7), and a phase difference calculation processing means (12) for calculating a phase difference corresponding to the twist generated in the drive shaft (1) from the rotation pulse signal detected by each of the sensors (6, 7) by calculation processing; A phase difference corresponding shaft torque calculating means (13) is provided for determining the shaft torque from the phase difference.
The phase difference calculation processing means (12)
The rotation speed of the drive shaft (1) is detected by the rotation pulse signal on the outboard side, the rotation pulse signal on the inboard side, or an external rotation sensor, and the frequency proportional to the detected rotation speed of the drive shaft (1) is detected. A rotation speed proportional pulse output means (18) for generating a pulse;
A twist angle corresponding phase difference calculating means (16) for obtaining a phase difference between the rotation pulse on the outboard side and the rotation pulse on the inboard side as a count value of the rotation number proportional pulse,
The frequency of the rotation speed proportional pulse output from the rotation speed proportional pulse output means (18) is (60 × drive shaft rotation speed (S) when the resolution of detecting the twist angle of the drive shaft (1) is S degrees. rpm) / S) Hz or higher.

  The shaft torque measurement method for a drive shaft according to the present invention is such that a sensor target is attached to 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 is opposed to the sensor target. Rotation pulse signals generated by detecting both sensor targets with the provided sensor are detected, and the phase difference of the rotation signal corresponding to the torsion generated in the drive shaft is calculated from the detected rotation pulse signal to calculate the shaft torque. In the calculation process of the phase difference, the rotation speed of the drive shaft is detected by an outboard rotation pulse signal, an inboard rotation pulse signal, or an external rotation sensor, and the detected drive shaft is detected. Generate a pulse with a frequency proportional to the rotation speed of the The phase difference between the rotation pulse and the rotation pulse on the inboard side is obtained as the count value of the rotation speed proportional pulse, and the frequency of the rotation speed proportional pulse is obtained when the resolution of detection of the twist angle of the drive shaft is S degrees , (60 × rotation speed of drive shaft (rpm) / S) Hz or more, the shaft torque acting on the drive shaft can be accurately measured, and the measured shaft torque is used for engine output control. By preventing excessive torque, it is possible to contribute to the weight reduction of the drive shaft, and it is possible to estimate the acting force between the road surface and the tire from the measured shaft torque.

  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 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 a front axle of a front wheel drive vehicle, that is, a front wheel axle, the front wheels are steered, so that the constant velocity joint 3 on the outboard side that is the wheel side is required to have a constant velocity 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 2 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, a barfield type sliding joint, a tripod type sliding joint, a cross globe joint, or the like is used for the inboard side constant velocity joint 2. The independent suspension type drive wheel rear axle does not require a steering function and does not require a large operating angle, so 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. The sensor targets 4 and 5 include a gear-like pulsar ring or a magnetic encoder in which N-pole and S-pole pairs are arranged in the circumferential direction. On the vehicle body side, sensors 6 and 7 made of electromagnetic pickups or the like are installed at positions close to these sensor targets 4 and 5, and when the sensor targets 4 and 5 rotate, the sensor 6 and 7 has a frequency proportional to the rotational speed. The pulse is generated. Corresponding sensor targets 4 and 5 and sensors 6 and 7 constitute rotation detectors 8 and 9 for detecting a rotation speed and a rotation angle, respectively.

  Here, in FIG. 1, the sensor system is configured by the sensor targets 4 and 5 made of a gear-like pulsar ring or magnetic encoder and the sensors 6 and 7 made of an electromagnetic pickup, but any sensor target may be used. Further, as the sensors 6 and 7, an optical sensor or another magnetic sensor may be used instead of the electromagnetic pickup.

FIG. 2 shows a conceptual configuration of this drive shaft axial torque measuring apparatus. This shaft torque measuring device includes a shaft torque calculation unit 11 and rotation detectors 8 and 9 on the inboard side and the outboard side.
The shaft torque calculation unit 11 includes a phase difference calculation processing means 12 for calculating a phase difference corresponding to the twist generated in the drive shaft 1 from the rotation pulse signals detected by the sensors 6 and 7, and the calculated phase difference. The phase difference corresponding shaft torque calculating means 13 for determining the shaft torque from
The shaft torque of the drive shaft 1 detected by the phase difference corresponding shaft torque calculation means 13 is used for travel control by the vehicle travel control means 31. The rotation pulse signal detected by the shaft torque measuring device 11 is used for controlling the antilock brake system 32.

  The phase difference calculation processing means 12 includes a rotation speed proportional pulse output means 18 and a twist angle corresponding phase difference calculation means 16 as its basic configuration.

The rotation speed proportional pulse output means 18 detects the rotation speed of the drive shaft 1 by an outboard rotation pulse signal, an inboard rotation pulse signal, or an external rotation sensor. It is a means for generating a pulse having a frequency proportional to the rotational speed. In the illustrated example, a constant frequency pulse is generated by the constant frequency pulse output means 14, and the period of the rotation pulse signal of the rotation detector 9 on the outboard side is counted by the constant frequency pulse counting means 15 with the constant frequency pulse. Thus, the rotational speed of the drive shaft 1 is detected. From the detected rotational speed of the drive shaft 1, a pulse having a frequency proportional to the rotational speed of the drive shaft 1 is generated by the rotational speed proportional pulse output means 18.
The twist angle corresponding phase difference calculation means 16 outputs the phase difference between the outboard side rotation pulse and the inboard side rotation pulse output from the rotation detectors 9 and 8, and the rotation speed proportional pulse output means 18 outputs. This is means for obtaining the count value of the number proportional pulse.
Details of the means 13 to 18 will be described together with a shaft torque measuring method described below.

  In addition, the phase difference calculation processing means 12 includes an abnormality determination means 19, a rotation direction detection means 20, a rotation direction correspondence calculation formula change means 21, an initial phase deviation correction means 22, a torque / phase difference relationship correction means 23, A pulse dividing unit 24 and a sensor position correspondence correcting unit 25 are provided. The functions of these means 19 to 25 will also be described together with the shaft torque measuring method described below.

A shaft torque measuring method using the shaft torque measuring device having the above configuration will be described.
At the time of sudden start and acceleration of the automobile, the shaft torque generated in the drive system is large, and the drive shaft 1 has the lowest rigidity excluding 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 calculated based on pulse signals from the sensors 6 and 7 including an electromagnetic pickup and the shaft torque is obtained.

  As shown in FIG. 3, when no torque is generated, there is no twist at both ends of the drive shaft 1, and the pulses by the sensor targets 4 and 5 on the inboard side and the outboard side are also in phase.

  However, since the drive shaft 1 is twisted when torque is generated, the pulses generated by the pulsar ring 5 on the outboard side are delayed from the pulses generated by the pulsar ring 4 on the inboard side, as shown in FIG. An increase in time to t occurs. In the figure, the falling edge of the inboard side rotation pulse and the falling edge of the outboard side rotation pulse are shown, but the phase difference between the rising edges of each signal may be used.

  Here, FIG. 4 shows a state in which the vehicle body is moving forward (forward rotation). Further, the inboard side pulsar ring 4 has a larger rotation angle than the outboard side pulsar ring 5, and the inboard side rotation pulse is More advanced than outboard side rotation pulse.

Therefore, as shown in FIG. 4, the time from the fall of the inboard side rotation pulse to the fall of the outboard side rotation pulse is from the fall of the outboard side rotation pulse to the fall of the inboard side rotation pulse. When Q is shorter than the time (that is, when Q <(K1 / 2), K1: number of pulses per pulsar ring rotation), the fall of the inboard side rotation pulse and the fall of the outboard side rotation pulse The phase difference detection pulse (FIG. 4 (f)), which is a rotation speed proportional pulse having a frequency proportional to the rotation speed of the drive shaft 1, is generated, and the phase difference detection pulse is counted to cope with the shaft torque. The phase difference due to the twist angle is obtained, and the shaft torque can be measured. The detection of the phase difference based on the counting of the phase difference detection pulses is obtained by the twist angle corresponding phase difference calculating means 16 of FIG.
Note that, as shown in FIG. 4E, a rotation speed proportional pulse may be always generated, and the number of pulses may be counted only between the falling edge of the inboard side rotation pulse and the falling edge of the outboard side rotation pulse.

If the frequency of this phase difference detection pulse is drive shaft rotation speed (rpm) / 60 × K1 (K1: number of pulses per rotation of pulsar ring), the shaft torque is K2 × Q / K1 (K2: constant) Calculated.

  The calculation of the shaft torque is performed by the phase difference corresponding shaft torque calculating means 13 in FIG. The torsion angle pair equal phase difference calculating means 16 and the phase difference corresponding shaft torque calculating means 13 are conceptually separated from each other. Specifically, one calculating means in which both means 16 and 13 are combined is used. It is done.

On the other hand, as shown in FIG. 5, the time from the fall of the outboard rotation pulse to the fall of the inboard rotation pulse is from the fall of the inboard rotation pulse to the fall of the outboard rotation pulse. When Q is shorter than the time (ie, when Q> (K1 / 2), K1: number of pulses per pulsar ring rotation), the shaft torque is K2 × (K1-Q) / K1 (K2: constant) Calculated.

  Here, the higher the pulse having a frequency proportional to the number of revolutions, the more sensitive the torsion between the inboard pulsar ring and the outboard pulsar ring can be measured. Therefore, when the resolution for detecting the twist of the drive shaft is S degrees, it is desirable that it is (60 × drive shaft rotation speed (rpm) / S) Hz or more.

  On the other hand, if the twist angle of the drive shaft 1, that is, the phase difference between the two sensor targets 4 and 5 becomes too large, the number of phase difference detection pulses may be erroneously counted. Therefore, in order to avoid such erroneous counting, assuming that the maximum twist angle to be measured is Bdeg, the twist is estimated by setting the number of teeth A of the sensor targets 4 and 5 such that B> (180 / A). The calculation method is simplified, and the reliability of shaft torque detection can be improved.

Further, when the twist angle of the drive shaft 1 corresponding to the measured shaft torque of the drive shaft 1 is equal to or greater than the assumed maximum twist angle Bdeg, an abnormal signal is output to the outside, thereby further detecting the shaft torque. The reliability of the drive shaft 1 can be improved, and at the same time, the drive shaft 1 can be prevented from being damaged.
The abnormality determining means 19 in FIG. 2 sets the assumed maximum torsion angle Bdeg, and outputs an abnormality signal when the torsion angle of the drive shaft 1 is equal to or greater than the set torsion angle.

  Moreover, even if the torque is not applied to the drive shaft 1 depending on the positions of the sensor target 5 and the sensor 7 on the outboard side and the positions of the sensor target 4 and the sensor 6 on the inboard side, the detected phase difference is May exist. For this reason, the rotation pulse signal on the outboard side and the rotation pulse signal on the inboard side have an outer ring of the constant velocity joints 2 and 3 so that the phase difference becomes zero when no torque is applied to the drive shaft 1. It is desirable to fix the sensor targets 4 and 5 consisting of pulsar rings to 2a and 3a or to adjust the phase angle of the sensors 6 and 7 consisting of electromagnetic pickups.

  If there is a phase difference between the rotation pulse signal on the outboard side and the rotation pulse signal on the inboard side of the drive shaft 1 in a state where no torque is applied to the drive shaft 1, this value is measured in advance. The calculation result of the phase difference at the time of measuring the shaft torque may be corrected. The initial phase shift correcting unit 22 in FIG. 2 is a unit that performs this correction.

As shown in FIG. 6, the relationship between the torque between the outer rings 2a and 3a of the constant velocity joints 2 and 3 and the phase difference is obtained in advance by measurement or calculation, and the torque and the twist angle inside the constant velocity joints 2 and 3 are obtained. The nonlinearity may be corrected. This makes it possible to measure the shaft torque more accurately.
The torque / phase difference relationship correcting unit 23 in FIG. 2 is a unit that stores the relationship between the torque and the phase difference obtained as described above and corrects the nonlinearity.

7A and 7B show an example in which the sensor targets 4 and 5 are pulsar rings and a magnetic encoder, respectively.
Regardless of whether the sensor target 4 or 5 is a pulser ring or a magnetic encoder, a plurality of sensors 6 and 7 that are installed facing the sensor target 4 and 5 are used, and fixed at a predetermined interval. Thus, as shown in FIG. 8, the rotational direction of the drive shaft 1 obtained from the outputs of the sensors 6 and 7 facing the same sensor target 4 and 5 can be detected. The rotation direction detection means 20 in FIG. 2 performs this rotation direction detection process. Based on this rotation direction detection result, the calculation method at the time of measuring the shaft torque is changed as described above.
The rotation direction may be detected by a sensor (not shown) provided outside.

FIG. 9 shows a calculation method at the time of forward rotation / reverse rotation when the counted number Q of phase difference detection pulses is less than half (U2) of the number of pulses U proportional to the rotation frequency.
In the case of Q <U / 2 shown in FIG. 9, the shaft torque during forward rotation is
(Shaft torque) = K3 x Q (K3: constant)
The shaft torque during reverse rotation is calculated as
(Axial torque) = K3 x (U-Q) (K3: Constant)
Is calculated as
FIG. 10 shows a calculation method at the time of forward rotation / reverse rotation when the counted number Q of phase difference detection pulses is larger than half of the number of pulses U proportional to the rotation frequency (U / 2).
In the case of Q> U / 2 shown in FIG. 10, the shaft torque during forward rotation is
(Axial torque) = K3 × (U−Q) / (Drive shaft rotation speed) (K3: Constant)
The shaft torque during reverse rotation is calculated as
(Axial torque) = K3 × Q / (Drive shaft speed) (K3: Constant)
Is calculated as
Thus, an accurate shaft torque is made possible by changing the calculation method at the time of measuring the shaft torque according to the rotation direction of the drive shaft 1 and the detected phase difference signal (Q).
The calculation method change according to the rotation direction is performed by the calculation method changing means 21 corresponding to the rotation method in FIG.

In addition, the wheel bearing speed detection rotation sensor (ABS sensor) is usually configured by the axle bearing portion fixed to the constant velocity joint 3 on the outboard side, but the accuracy is high, and the rotation pulse per rotation is high. The number is as large as about 50 pulses.
Therefore, in order to use the rotation pulse detected by the constant velocity joint 3 as this ABS sensor, it is necessary to increase the resolution. In order to increase this resolution, when the sensor target 5 is a pulsar ring, the widths of the convex and concave portions of the teeth are the same, and when the sensor target 5 is a magnetic encoder, the poles of the S pole and the N pole Make the interval approximately the same. Furthermore, the outputs of the plurality of sensors 7 installed facing each sensor target 5 have a phase difference of (180 /) deg when the number of sensors is D. Further, the pulse output due to the unevenness or pole change of the sensor target is divided into D by the output of these sensors to obtain this D-divided pulse output, which is used as a wheel rotation speed signal for controlling the antilock brake system 32. It may be used as

FIG. 11 and FIG. 12 show examples using two or three sensors 7 (6), respectively. By configuring the logic as shown in the table in the figure, it is possible to obtain an output of a pulse whose frequency is increased by pulse division from the output of each sensor 7 (6). In the table, “H” indicates a high level and “L” indicates a low level. “Sensor 1”, “Sensor 2”,... Are the same sensor 7 or sensor 6 with reference numerals “1” and “2” added to distinguish the sensors arranged in the circumferential direction. is there.
The pulse dividing means 24 in FIG. 2 performs pulse division as shown in FIG.

  Further, the position of each sensor is adjusted so that the outputs of the D sensors 6 and 7 installed facing the sensor targets 4 and 5 have a phase difference of (180 / D) deg. The phase difference is detected from the measurement results of both sensor outputs in advance so that the outputs of the D sensors 6 and 7 placed opposite to 4 and 5 have a phase difference of (180 / D) deg. The accuracy of the ABS sensor may be improved by correcting the output of the rotation detection pulse based on the detected phase difference and the rotation speed of the sensor target.

  In each of the above examples, the sensors 6 and 7 are opposed to the sensor targets 4 and 5 from the radial direction, but may be opposed to each other in the axial direction as shown in FIG.

  The vehicle control device 31 of FIG. 2 performs engine control such as delaying the ignition timing of the engine, for example, based on the shaft torque signal thus obtained. By doing so, generation of excessive torque can be prevented. If the occurrence of excessive torque can be prevented, the shaft diameter of the drive shaft 1 and the outer diameters of the constant velocity joints 2 and 3 can be reduced. Further, the measured state of the shaft torque can be used to estimate and grasp the slip condition between the road surface and the tire and can be used for traveling control.

  The vehicle control device 31 of FIG. 2 uses the shaft torque signal obtained as described above for further engine control for traction control, AT transmission control, and travel control such as electronic control LSD. May be.

As is apparent from the above description, in this embodiment, one additional sensor target 4 made of pulsar ring or the like is added to the drive shaft 1 with the sensor target 5 made of ABS pulsar ring or the like to thereby increase the shaft torque. Therefore, the shaft torque of the drive shaft 1 can be detected at a very low cost. Further, as described above, the shaft torque can be accurately measured. And generation | occurrence | production of an excessive torque can be suppressed by performing engine control based on the signal of a shaft torque. Therefore, the size of the shaft of the drive shaft 1 and the constant velocity joints 2 and 3 can be reduced, which contributes to the weight reduction of the vehicle. In addition, the fuel efficiency of the automobile is improved by being able to reduce the weight.
Moreover, optimal control is possible by using the shaft torque for travel control. For example, it can be used as a drive shaft torque signal for engine control necessary for traction control. By adding drive shaft torque control to the AT transmission, efficiency is improved and fuel efficiency is improved. Optimal torque distribution can be obtained by adding drive shaft torque control to the electronic control LSD.

It is a longitudinal cross-sectional view of the drive shaft and constant velocity joint which apply the axial torque measuring method and measuring apparatus concerning one Embodiment of this invention. It is a block diagram which shows the conceptual structure of a coaxial torque measuring device. It is a time chart of the pulse which generate | occur | produces by rotation of a sensor target. It is a time chart which shows the relationship between the pulse which generate | occur | produces by rotation of a sensor target, and a phase difference detection pulse. It is a time chart which shows another example of the relationship between the pulse which generate | occur | produces by rotation of a sensor target, and a phase difference detection pulse. It is a graph which shows the relationship between a torque and a phase angle. It is explanatory drawing of a sensor attachment phase. It is explanatory drawing regarding a rotation direction and its calculation. It is explanatory drawing which shows the axial torque calculation method by the relationship between a phase difference detection pulse and a rotation speed proportional pulse. It is explanatory drawing which shows the axial torque calculation method in the example from which the relationship between a phase difference detection pulse and a rotation speed proportional pulse differs from FIG. It is calculation logic explanatory drawing in case the number of sensors is two. It is calculation logic explanatory drawing in case the number of sensors is three. It is explanatory drawing of the modification of a sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Drive shaft 2, 3 ... Constant velocity joint 4, 5 ... Sensor target 6, 7 ... Sensor 8, 9 ... Rotation detector 11 ... Axis torque calculating part 12 ... Phase difference calculation processing means 13 ... Phase difference corresponding | compatible axis torque calculation Means 14 ... Constant frequency pulse output means 15 ... Constant frequency pulse count means 16 ... Twist angle-corresponding phase difference calculation means 18 ... Rotational speed proportional pulse output means

Claims (13)

At both ends, a sensor target is attached to the outer ring of each constant velocity joint of the drive shaft that is connected to the drive system of the car via a constant velocity joint, and both sensor targets are detected by a sensor provided facing this sensor target. A method for detecting a generated rotation pulse signal and calculating a phase torque of a rotation signal corresponding to a twist generated in the drive shaft from the detected rotation pulse signal to obtain a shaft torque,
In the calculation processing of the phase difference, the rotation speed of the drive shaft is detected by the rotation pulse signal on the outboard side, the rotation pulse signal on the inboard side or an external rotation sensor, and is proportional to the detected rotation speed of the drive shaft. A frequency pulse is generated, and the phase difference between the rotation pulse on the outboard side and the rotation pulse on the inboard side is obtained as a count value of the rotation speed proportional pulse,
The frequency of the rotation speed proportional pulse is (60 × drive shaft rotation speed (rpm) / S) Hz or more when the resolution of detection of the twist angle of the drive shaft is S degrees. Shaft torque measurement method. In claim 1, the sensor target has a plurality of teeth or pole pairs equally arranged in the circumferential direction, the number of the teeth or pole pairs is A, and the maximum twist angle to be measured is Bdeg.
B> (180 / A)
A method for measuring shaft torque of a drive shaft.   3. The rotation pulse signal on the outboard side and the rotation pulse signal on the inboard side according to claim 1 or 2, wherein the phase difference between the rotation pulse signal on the outboard side and the rotation pulse signal on the inboard side is constant speed so that the phase difference becomes zero. A method for measuring the axial torque of a drive shaft in which the sensor target is fixed to the outer ring of the joint or the phase angle of the sensor is set.   4. The phase difference between the rotation pulse signal on the outboard side and the rotation pulse signal on the inboard side of the drive shaft in a state where torque is not applied to the drive shaft according to claim 1. The shaft torque measurement method for the drive shaft corrects the calculation result of the phase difference at the time of measuring the shaft torque based on the obtained value.   5. The relationship between the torque between the outer rings of both constant velocity joints and the phase difference is obtained in advance by measurement or calculation before detecting each rotation pulse signal in any one of claims 1 to 4. A method for measuring the shaft torque of the drive shaft, wherein the calculation result of the phase difference at the time of measuring the shaft torque is corrected based on the relationship between the obtained torque and the phase difference.   6. The abnormality signal according to claim 1, wherein when the drive shaft twist angle corresponding to the measured drive shaft axial torque is equal to or larger than the set maximum twist angle Bdeg, Of shaft torque of the drive shaft output to   7. The method for measuring an axial torque of a drive shaft according to claim 1, wherein a plurality of sensors installed opposite to each sensor target are used, and the plurality of sensors are fixed at a predetermined interval. .   8. The rotational direction of the drive shaft is detected from the output of the sensor facing the same sensor target, or the rotational direction of the drive shaft is detected by an external sensor, and the detection result of the rotational direction is obtained. Originally, the shaft torque measurement method of the drive shaft that changes the calculation formula of the phase difference when measuring the shaft torque.   9. The sensor according to claim 1, wherein each of the sensor targets has a plurality of teeth or magnetic pole pairs equally arranged in a circumferential direction, and the teeth adjacent to the thicknesses of the teeth of the sensor targets. Or the width of the pole pair and the pole spacing of the pole pair are substantially the same, and a plurality of sensors are arranged facing each sensor target, and the outputs of these sensors are the same as the number of sensors. If the number is D, the phase difference of (180 / D) deg is set, and the output of these sensors divides the pulse output due to unevenness or pole change due to the dentition of the sensor target into D parts, and this D-divided pulse output is A method for measuring the shaft torque of a drive shaft used as a control signal for an antilock brake system.   10. The method for measuring axial torque of a drive shaft according to claim 9, wherein the positions of the respective sensors are set so that the outputs of the D sensors installed facing the respective sensor targets have a phase difference of (180 / D) deg.   10. The measurement result of each sensor output facing both sensor targets in advance so that the outputs of the D sensors placed facing each sensor target have a phase difference of (180 / D) deg from each other. The phase difference of the drive shaft is detected and stored, and the rotation detection output of the sensor is corrected based on the stored detection value and the rotation speed of the sensor target.   12. A travel control method for an automobile, wherein the shaft torque signal obtained by the shaft torque measurement method for a drive shaft according to claim 1 is used for vehicle travel control. A sensor target is attached to 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 detected opposite to this sensor target. A sensor for detecting a rotation pulse signal is provided, and a phase difference calculation processing means for calculating a phase difference corresponding to a twist generated in the drive shaft from the rotation pulse signal detected by each of these sensors by calculation processing, and an axis from the obtained phase difference A phase difference corresponding shaft torque calculation means for obtaining torque is provided,
The phase difference calculation processing means includes:
Rotation speed at which the rotation speed of the drive shaft is detected by the rotation pulse signal on the outboard side, the rotation pulse signal on the inboard side, or an external rotation sensor, and a pulse having a frequency proportional to the detected rotation speed of the drive shaft is generated. Proportional pulse output means;
A torsion angle corresponding phase difference calculating means for obtaining a phase difference between the rotation pulse on the outboard side and the rotation pulse on the inboard side as a count value of the rotation number proportional pulse,
The frequency of the rotation speed proportional pulse output by the rotation speed proportional pulse output means is (60 × drive shaft rotation speed (rpm) / S) Hz when the resolution of detection of the twist angle of the drive shaft is S degrees. And above
An axial torque measuring device for a drive shaft characterized by the above.

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