JPS61223525A - Torque detector - Google Patents

Abstract

PURPOSE:To form a torque detector which enables highly accurate detection of torque, by arranging two pickups each on rotors so as to be positioned mechanically at 180 deg. therebetween while being shifted in the output phase by 180 deg. to eliminate error contained in the output signal. CONSTITUTION:Two each of pickups 1A, 1B, 2A and 2B are provided on respective rotors 3 and 4 and differential amplifiers 15 and 16 into which output signals of the pickups are arranged in front of waveform rectifiers 5 and 6. In the case of even gears with the number of teeth of gears represented by N, the pitch between the pickups 1A and 1B and that between the pickups 2A and 2B shall be (N/2)+(1/2) or (N/2)-(1/2). In this case, as the top priority is put on cancelling magnetic attracting force of electromagnetic type pickups, slight effect remains due to relative values of the two rotors 3 and 4 but this poses no problem in practice. In the case of odd gears, both the pitches shall be N/2. In the case of odd gears, both the pitches shall be N/2. In this case, the mechanical and electrical angles are set at 180 deg. in the phase difference.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a torque detection device, and particularly to a torque detection device built into an electric motor.

[Prior art and its problems]

FIG. 5 shows a conventional torque detection device.

In the figure, 1 is a drive-side pickup installed on the motor side, 2 is an output-side pickup installed on the load side, 3 is a rotating body on the driving side, 4 is a rotating body on the output side, 5.6 is a waveform shaper, and 7 is a rotating body on the output side. 8 is a phase discriminator, 8 is a differential amplifier, 9 is an 0-pass filter, and 10 is a constant length torque transmitting means such as a torsion bar capable of transmitting torque from the drive side 100 to the output load side 10L. The pickup 1.2 is, for example, an electromagnetic pickup, and outputs changes in magnetic flux caused by protrusions of the rotating bodies 3 and 4, which are gears, as electrical signals 81.82.

As mentioned above, the rotating bodies 3.4 are gears each having a plurality of protrusions on the outer periphery, and are fixed to the torsion bar 10 at regular intervals along the longitudinal direction of the torsion bar 10, which can be slightly "twisted." ing.

A circuit consisting of waveform shapers 5, 6, phase discriminator 7, differential amplifier 8, and low-pass filter 9 outputs pickup output signals S1. This is for obtaining a torque value as an electrical signal based on S2.

Next, the operation of this conventional example will be explained.

The torsion bar 10 transmits torque from a drive side 10D such as an electric motor to an output side 10L. However, at this time, a slight "twist" occurs in the torsion bar 1010, and even if the gears 3.4 are the same, the pickup 1.
A phase difference occurs between the two output signals 81 and 82.

The waveform shapers 5 and 6 shape the output phase signals 81 and 82 of these pickups 1 and 2 so that they are easy to process, and obtain a torque signal S3 via a phase detector 67, a differential amplifier 8, and a low-pass filter 9.

However, such conventional technology has the following drawbacks.

That is, according to the prior art as described above, gears 3.4
The center may deviate from the center of rotation depending on the accuracy of machining and assembly of the gear itself and the accuracy of machining and assembly of the drive shaft 10D and output load shaft 10L of the torsion bar 10.

With such relative eccentricity, pickups 3 and 4
The phase difference between the output signals 81 and 82 fluctuates in synchronization with the rotation, and a spurious torque fluctuation appears in the rotation period.

A low-pass filter 9 or the like is used to remove this, and the spurious torque fluctuations are reduced by electrical signal processing through filtering.

However, with such a method, it is inevitable that the response characteristics will deteriorate.

Also, if the pickup is an electromagnetic type, the pickup 3
．． 4 includes a ferrite magnet, so when one end of the gear 3.4 approaches or moves away from the pickup, an attractive force acts to pull the gear in or out, respectively. For this reason, the torque was not uniform and cogging torque was generated.

This kind of cogging torque is caused by so-called inverters and other AC
When operating at variable speed with a variable speed drive device, the output frequency f of the pickup is a torsion bar 10 that transmits torque.
at the natural frequency of. This is likely to occur because the torsion bar 10 causes "torsional" resonance in the low-speed rotation range that coincides with
This rotation speed was causing an error.

Furthermore, cogging torque that causes such an error occurs even when there is no resonance, and becomes a torque output signal in a form superimposed on the torque to be transmitted. For this reason, the torque output generally includes errors in the low-speed rotation range where filtering processing is difficult. .

[Purpose of the invention]

The present invention was made in an attempt to eliminate the drawbacks of the prior art as described above, and an object of the present invention is to provide a torque detection device that eliminates errors included in the output signal and is capable of highly accurate torque detection. .

[Summary of the invention]

In order to achieve this object, according to the present invention, two pickups are provided on each rotating body so that they are mechanically arranged at 180 degrees and output phases are shifted by 180 degrees.

In other words, for each gear, by placing two pickups at positions shifted by 180 degrees in mechanical angle,
The effects of relative eccentricity of each gear are removed.

Also, mechanical angle is (N/2) + (1/2) pitch or (
By placing the two pickups at positions with a pitch difference of N/2) - (1/2) (N is the number of teeth on the gear), therefore 180 degrees in electrical angle, the magnetic attraction force of the electromagnetic pickup is canceled out. be able to.

(Embodiments of the Invention) The present invention will be described in detail below with reference to the accompanying drawings. In each drawing, the same reference numerals indicate the same objects.

FIG. 1 is a detailed explanatory diagram of the present invention.

This embodiment differs from the conventional example shown in FIG.
, 2 big-up IA, I for each of 4
In addition, a differential amplifier 15 and 16 for inputting the output signal of each pickup is provided at the front stage of the waveform rectifier 5.6.

As shown in FIGS. 2 to 4, the pickups IA, 2A, IB, and 2B each have a winding 23 wound around both legs of a U-shaped yoke 22. Regarding these windings, the terminals of the pickup 1A are connected to one terminal 11 of the amplifier 15, and the terminals of the compensation pickup 1B are connected to the amplifier 15.
The terminal of the pickup 2A is connected to the other terminal 12 of the amplifier 1116, and the terminal of the compensation pickup 2B is connected to the other terminal 14 of the amplifier 16.
connected to.

Here, the external dimensions of the gears 3 and 4 differ depending on the model and capacity of the electric motor incorporating the torque detection device. For this reason, if the electromagnetic pickup is made to be versatile so that it can be used with all types of devices, depending on the module, some gears will have an even number of teeth and some will have an odd number of teeth.

Therefore, the arrangement of the pickups for even-numbered gears and odd-numbered gears is as follows, assuming that the number of teeth of the own vehicle is N.

(1) In the case of even-numbered cars As shown in Figure 2 or Figure 3, pick-up 1A and 1
The pitch of B's cabinet and the pitch between pickups 2A and 28<7) shall be (N/2) + (1/2) or (N/2) - (1/2), respectively.

In this case, since priority is given to canceling the magnetic attraction force of the electromagnetic pickup, the influence of the relative eccentricity of both rotating bodies 3.4 remains to some extent, but there is no practical problem.

(2) In the case of odd number gears As shown in Figure 4, the pitch between pickups 1A and 1B and the pitch between pickups 2A and 2B are both N.
/2. In this case, both mechanical angle and electrical angle are 18
The phase difference is 0 degrees.

Next, the operation of this embodiment will be explained.

Each output signal S of each pickup IA, 18.2A, 2B
A1. SA2, 881.882 is a sinusoidal alternating voltage, and the output signals SA1 and 88 of pickups IA and IB are
1 and the output signal SA of pickups 2A and 2B.
The phase difference between 2 and 882 is 180 degrees each.

Therefore, the output signals SB1, 882 of the compensation pickups IB, 2B are inverted by the differential amplifiers 15, 16, and added to the output signals SA1, 8A2 of the pickups IA, 2A.

The subsequent signal processing is the same as the conventional one. That is, the output signals 85.86 of the differential amplifiers 15.16 are input to the waveform rectifiers 5.
6, the phase is determined by the phase discriminator 7, and the output terminal T1
．． From T2, pulse signals representing phase lead or lag are obtained. If this pulse signal is amplified by the differential amplifier 8 and smoothed by the low-pass filter 9, the
Torque signal S3 outputs a DC voltage proportional to the amount of twist
can be obtained as

In addition, the differential amplifiers 15 and 16 described above can be used by connecting the windings in series with opposite polarities for each pickup of each rotating body, as long as the impedance and voltage of the pickup do not interfere with subsequent processing. There may be cases where you don't have to.

(Effects of the Invention) According to the present invention, as described above, two pickups are provided on each rotating body so that they are mechanically arranged at 180 degrees and the output phases are shifted by 180 degrees. , the following descent! l! It is possible to provide a torque detection device that does the following. That is, (1) the apparent torque fluctuations synchronized with rotation caused by the relative eccentricity of both gears can be canceled out, and high torque detection accuracy can be obtained.

(2) Since signal processing is not performed using a low-pass filter, response characteristics are also improved.

(3) Since it is possible to prevent the "torsion" resonance of the torque transmission means in the low speed range that was caused by the magnetic attraction force of the electromagnetic pickup, the measurement range is expanded especially in the low speed range, making it possible to measure torque over a wide speed range. becomes.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention, FIGS. 2 to 4 are explanatory diagrams of main parts of the embodiment of FIG. 1, and FIG. 5 is a system diagram of a conventional device. IA, 18.2A, 2B...Pickup, 3°4.
... Rotating body, 5.6... Waveform shaper, 7... Phase discriminator, 8.15.16-... Differential amplifier, 9... 0-
Bass filter, 10... Torsion transmission means, 21.
...Ferrite magnet, 22...Yoke, 23...Coil.

Claims (1)

[Claims] A torque transmitting means capable of transmitting torque from the driving side to the output side, and at least two rotating parts fixed at regular intervals along the longitudinal direction of the torque transmitting means and each having N protrusions on the outer periphery. A torque detection device comprising: a pickup that responds to irregularities of the protrusion of each rotating body; and torque detection means that detects torque from a phase difference between outputs of the pickup corresponding to each of the rotating bodies, Two pickups are provided for one rotating body, and N
If is an even number, the two pickups are (N/2)
Arranged with a pitch interval of + (1/2) or (N/2) - (1/2), and if N is an odd number, the two pickups are arranged at a pitch interval of N
A torque detection device characterized in that the devices are arranged at a pitch interval of /2.