JPH03279831A - Torque detector - Google Patents

Abstract

PURPOSE:To decide the application direction of torque by regarding one of phase signals read out of at least >=3 encoders as a reference signal, and finding >=2 phase differences with other phase signals and comparing the phase differences. CONSTITUTION:The pulse waveforms of the phase signals which are read out by respective magnetic heads 3a, 3b, and 3c are in phase with one another when non torque load is placed on the rotary shaft 1. When a torque load is placed on the rotary shaft 1 from the driving source side to the load side or when the torque load is placed from the load side to the driving source side, the waveforms becomes out of phase with one another. Namely, a torque calculation part 4 judges from which of the magnetic heads 3a and 3c a one-shot pulse signal arrives about the one-shot pulse of the signal read out by the magnetic head 3a as the reference signal to detect the application direction of the torque load.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a torque detection device that detects the torque of a rotary shaft that is rotationally driven, and in particular, the present invention relates to a torque detection device that detects the torque of a rotary shaft that is rotationally driven. This invention relates to an on-vehicle torque detection device that calculates from the amount of twist in the vehicle.

(Prior Art) In recent years, the need for torque detection in automobiles has been increasing. In particular, accurate torque detection is required when distributing torque to the front wheels and rear wheels of a four-wheel drive vehicle. However, current torque detection is performed by setting a characteristic curve for the driving condition and using indirect control through estimation, and its accuracy is not necessarily sufficient due to variations in characteristics among vehicles. . A similar problem is
This problem also occurs in the torque detection of various mechanical parts of vehicles that have an output shaft, such as automatic transmissions. Under these circumstances, if it becomes possible to directly detect torque in a car, it will not only be possible to detect torque distribution in the transmission and four-wheel drive, but also to
It is possible to achieve a high degree of perfection in active suspension and traction control. On the other hand, the necessity of torque detection is a problem not only in automobiles but also in various fields. For example, in NC machine tools, optimizing the torque is essential to ensure machining accuracy.

As a direct means of torque detection, there is a method of detecting the strain generated on the rotating shaft surface or the torsional stress of the rotating shaft and detecting the torque from the detected value, but both methods have problems in terms of measurement accuracy and reproducibility. Therefore, it is effective to detect the torque using a method of detecting the torsion angle of the rotating shaft, which is less likely to cause such problems.

As a conventional technique for detecting the torsion angle, two slit plates with a large number of slits are provided at a predetermined interval on a shaft rotated by a drive source, and a light emitting element is placed facing each other through the slits of the slit plates. By applying the fact that the overlapping area of the slit changes due to the relative torsional displacement of the shaft, we can calculate the change in the amount of light reaching the light receiving element from the light emitting element through the overlapping area, and the relative torsion angle from the installation interval. Two gears with multiple teeth are placed at a predetermined interval on a shaft rotated by a drive source, and an electromagnetic pickup is installed opposite the gears to detect relative torsional displacement of the shaft. A method of detecting from the output signal of an electromagnetic pickup is known.

Furthermore, two magnetic signal generating means or magnetic recording means are attached to the rotating shaft at a predetermined interval, and phase signals of the same phase are recorded in each means, and the signals are read from these means when torque is applied. A method of detecting the torsion angle from the phase difference of the signals is known (Japanese Patent Laid-Open No. 82-1
No. 50644, Japanese Patent Application Publication No. 12-239031).

(Problems to be Solved by the Invention) However, the method of detecting the torsion angle of the rotating shaft using the optical or electromagnetic pickup described above has a complicated and large structure, and is inappropriate as an on-vehicle torque detector. In addition, when detecting the drive shaft torque of a vehicle, since torque is generated from the load side to the drive side in engine braking, etc., it is necessary to simultaneously determine the direction of the torque applied to the rotating shaft. Depending on the prior art, it is difficult to determine the torque direction.

On the other hand, although the above-mentioned method of magnetically detecting the torsion angle of the rotating shaft has a simple structure, it is difficult to detect the direction of the torque applied to the rotating shaft as in the above-mentioned conventional technique. be.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a torque detection device that can also determine the torque direction with a simple configuration.

(Means for Solving the Problems) A torque detection device of the present invention calculates the torque applied to a rotating shaft, and includes an encoder section for detecting a torsion phase arranged at a predetermined interval in the axial direction of the rotating shaft. The direction of the torque applied to the rotating shaft is determined by determining the phase difference between one of the signals from these encoders and the other phase signals as a reference. It is characterized by: That is, at least three signal recording media are attached to the rotating shaft at a predetermined distance and have phase signals of the same phase recorded with each other, and these signal recording media are used to read the phase signals recorded on the signal recording media. A signal reading means provided corresponding to each medium, and a phase difference detection device that uses one of the plurality of read phase signals as a reference signal and detects a phase difference between this reference signal and other phase signals. and torque direction determining means for comparing the detected phase differences with each other and determining the direction of application of the torque applied to the rotating shaft based on the comparison result.

(Function) According to the above-mentioned configuration, at least three phase signals read from each signal recording medium as an encoder will all have the same phase when the rotating shaft is not twisted, but when torque is applied to this rotating shaft. When twisting occurs, a phase difference occurs between them. When one of the phase signals is used as a reference signal and the phase difference between the reference signal and the other phase signal is calculated, at least two phase differences are obtained. By considering the comparison results between the intervals between the signal recording media and the phase differences, it is possible to detect the magnitude and direction of the torque applied to the rotating shaft.

(Example) An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a torque detection device according to an embodiment of the present invention. This device includes three magnetic recording media 2a, 2b, and 2c mounted at three positions spaced apart from each other by a predetermined distance j in the axial direction of a rotating shaft 1 to be detected, and each magnetic recording medium 2a, It has magnetic heads 3a, 3b, 3c for recording and reproducing arranged at positions where phase signals can be recorded and reproduced with respect to 2b, 2c, and the rotating shaft 1 is connected to the magnetic recording medium 2a side (first It is connected to a drive source on the left side in the figure, and to a load on the magnetic recording medium 2c side (on the right side in Figure 1). Moreover, the three magnetic heads 3a, 3b, 3c each have
A signal generating section (not shown) that generates a phase signal for recording the phase signal on the magnetic recording media 2a, 2b, 2c, and a rotating shaft that shapes the waveform of the reproduced phase signal and based on the comparison result of each signal. 1 is connected to a torque calculation unit 4 that calculates the magnitude and direction of torque applied to the motor.

Further, the three magnetic recording media 2a, 2b, and 2c are set in advance so that the rotating shaft 1 is unloaded and rotates at a predetermined constant speed, and the same predetermined frequency (for example, 5 kHz) is applied to the three magnetic recording media 2a, 2b, and 2c from the signal generator. A phase signal consisting of a square wave signal is recorded.

The magnetic recording media 2a, 2b, and 2c are made by coating a magnetic layer made of magnetic metal or magnetic oxide on a long flexible nonmagnetic substrate, and the magnetic layer is placed on the outside of the rotating shaft 1. It is bonded to the rotating shaft 1 so as to go around the circumference. Further, the torque calculation section 4 includes both magnetic heads 3a,
A waveform shaping circuit that shapes the phase signals read by 3b and 3c into square wave signals, a one-shot multivibrator circuit that detects the rising edge of these square wave signals,
Based on this detected time interval of rising, the rotation axis 1
It has a CPU that calculates the torque value and torque direction applied to the engine, and signals representing the calculated torque value and torque direction are sent from the output section 5 to an external display circuit, torque control circuit, or the like.

Next, a method for determining the direction of torque will be explained. In this embodiment, when no torque load is applied to the rotating shaft 1, the pulse waveform after waveform shaping of the phase signal read out by each of the magnetic heads 3a, 3b, and 3c is
As shown in Figure (1), both signals have the same phase. If a torque load is applied to the rotating shaft 1 from the drive source side to the load side, as shown in Fig. 2 (2), and if a torque load is applied from the load side to the drive source side, the second Figure (3
) The phase shifts as shown in Here, the magnetic head 3b
Based on the signal read out by the magnetic head 3b,
The time interval (phase difference) between the signals read out by the magnetic helad 3a and Δt6. Magnetic head 3b and magnetic head 3c
The time interval (phase difference) of the signal read out by Δt
c, when the direction of torque is from the drive source side to the load side, Δta>Δtc, and conversely, when the direction of torque is from the load side to the drive source side, Δta<Δtc. Therefore, in the torque calculating section 4, the one-shot pulse of the signal read by the magnetic head 3b is used as a reference, and the torque is calculated by determining whether the next one-shot pulse signal is caused by the magnetic head aa or se. The direction in which the load is applied is detected.

Note that in the above embodiment, the reference signal for comparison is the signal read by the magnetic head 3b;
The reference signal is not necessarily limited to this, and a signal read by the magnetic head 3a or 3c may be used as the reference. It is also possible to obtain a one-shot pulse from the falling edge of the read phase signal.

Note that if the phase signals deviate from each other by more than half a cycle due to twisting of the rotating shaft, the above-mentioned relationship between Δta and Δtc will be reversed, so to prevent such a reversal, the expected phase difference must be within half a cycle. It is necessary to set the frequency of the above phase signal so that

Further, the torque value is calculated as follows. That is,
From the value of Δta above and the rotational speed of the rotating shaft 1, the torsion angle θ
The torque value T is calculated by substituting this torsion angle θ into the formula below.

32I! However, θ: torsion angle (rad) G: transverse elastic modulus of rotating shaft (υ/ai) 1・distance of magnetic recording medium D: diameter of rotating shaft Note that all calculations regarding the above phase difference are performed in the torque calculating section 4. Ru.

Note that in this embodiment, both adjacent magnetic heads 3a
, 3b, the torque value is calculated based on the phase difference between the phase signals read by the magnetic heads 3b, 3c that are adjacent to each other on the load side, or the magnetic heads 3a, 3a at both ends.
It is also possible to calculate the torque value based on the phase difference between the phase signals read out by 3c. Furthermore, if higher accuracy is required depending on the torque load situation, it is also possible to calculate the torque value from the phase difference between the three phase signals and further process the calculated value.

Note that in the above-described embodiment, three magnetic recording media 2a, 2b, and 2c are provided for the rotating shaft 1, but the present invention is not limited to this, and four or more magnetic recording media may be provided. You can also do it. Further, the shape of the magnetic recording medium used in the apparatus according to the present invention is not necessarily limited to the shape described above, and various other shapes can be used.

Note that, as shown in FIG. 1, all the three magnetic heads 3a, 3b, and 3e do not necessarily have to be arranged in corresponding positions; It is also possible to arrange them at positions shifted in the circumferential direction of the magnetic recording medium.

In short, it is sufficient that the phase signals read from all the magnetic heads have the same phase in the no-load state.

Note that this embodiment describes a torque detection method using a magnetic recording medium as an encoder, but the method is not limited to this, and if the device structure can be simplified, an electromagnetic pickup type or an optical type can be used. It is also possible to apply the equal ground phase difference type torque detection method.

Although the above embodiments are mainly explained using the power transmission system of an automobile as an example, the present invention is not limited to automobiles, but can also be applied to ships, construction vehicles, weapons, etc. .

(Effects of the Invention) As explained above, according to the torque detection device of the present invention, one of the phase signals read from each of at least three encoders is used as a reference signal, and this reference signal and other phase signals The direction of the torque applied to the rotating shaft can be easily determined from the arrangement order of the encoders related to each phase signal. I can do it.

Further, since the present device may be constructed from an encoder, a signal reading means, and a simple circuit for calculating signals, the device structure does not become complicated.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a torque detection device according to an embodiment of the present invention, and FIG. 2 is a signal waveform diagram for explaining signal processing in the torque calculation section shown in FIG. 1. 1...Rotating shafts 2a, 2b, 2c...Magnetic recording medium 3a, 3b, 3c...Magnetic head 4...-Torque calculating section

Claims (1)

[Claims] At least three signal recording media that are attached to a rotating shaft at a predetermined distance and on which phase signals of the same phase are recorded, and a phase signal recorded on these signal recording media. A signal reading means is provided corresponding to each of the signal recording media for reading, and one of the plurality of phase signals read by the signal reading means is used as a reference signal, and this reference signal and other phase signals are a phase difference detection means for detecting a phase difference between the two; and a torque direction determination means for comparing the phase differences detected by the phase difference detection means with each other and determining the direction of application of torque applied to the rotating shaft based on the comparison result. A torque detection device comprising: