JPH0450972B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Technical Field] 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 and 6 are waveform shapers, and 7 8 is a phase discriminator, 8 is a differential amplifier, 9 is a low-pass filter, and 10 is a constant length torque transmitting means such as a torsion bar capable of transmitting torque from the drive side 10D to the output load side 10L. The pickups 1 and 2 are, for example, electromagnetic pickups, and output changes in magnetic flux caused by protrusions of rotating bodies 3 and 4, which are gears, as electrical signals S1 and S2.

As mentioned above, the rotating bodies 3 and 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. .

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

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

The torsion bar 10 is connected to a drive side 10 such as an electric motor.
Torque is transmitted from D to the output side 10L. However, at this time, a slight "twist" occurs in the torsion bar 10, and even if the gears 3 and 4 are the same, the output signals S1 and S of the pickups 1 and 2 are
2, a phase difference occurs.

The waveform shapers 5 and 6 are connected to these pickups 1 and 2.
The output phase signals S1 and S2 are shaped to be easy to process, and are passed through a phase discriminator 7, a differential amplifier 8, and a low-pass filter 9 to obtain a torque signal S3.

However, such conventional technology has the following drawbacks.

That is, according to the conventional technology as described above, the centers of the gears 3 and 4 are determined by the precision of the processing and assembly of the gears themselves.
Also, the drive shaft 10D of the torsion bar 10 and the output load shaft 10L were sometimes deviated from the center of rotation depending on the machining and assembly accuracy.

When such relative eccentricity exists, the phase difference between the output signals S1 and S2 of the pickups 3 and 4 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 by filtering.

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

Furthermore, if the pick-up is an electromagnetic type, since the pick-ups 3 and 4 contain ferrite magnets, when the tips of the teeth of the gears 3 and 4 approach or move away from the pick-up, the gears are pulled in or pulled back, respectively. A suction force is applied. For this reason, the torque was not uniform and cogging torque was generated.

_Such cogging torque is generated when the torsion bar ₁₀ is " This tends to occur due to torsional resonance, which causes errors at this rotation speed.

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 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 thereof is to provide a torque detection device that eliminates errors included in the output signal and is capable of highly accurate torque detection. do.

[Summary of the invention]

To achieve this objective, according to the invention, two pickups are provided on each rotating body, mechanically arranged at 180 degrees and output phase shifted by 180 degrees.

That is, for each gear, the mechanical angle is 180 degrees from each other.
By placing the two pick-ups at offset positions, the effects of relative eccentricity of each gear are eliminated.

Further, the number of the gears is provided as an even number N,
Pick up those two (N/2) + (1/
2) or arranged at a pitch interval of (N/2) - (1/2), or, alternatively, the number of the gears is N, which is an odd number, and the two pick-ups are arranged at a pitch interval of N/2, This device detects torque from the phase difference between the outputs of the pickups corresponding to the respective rotating bodies.

Therefore, by arranging two pick-ups at 180 electrical degrees, the magnetic attraction force of the electromagnetic pick-up can be canceled out.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that in each figure, the same reference numerals indicate similar objects.

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

This embodiment is different from the conventional example shown in FIG. 1
5 and 16 in the front stage of the waveform rectifiers 5 and 6.

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

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 an electromagnetic pickup is made to be versatile so that it can be used with all types of models, some gears will have an even number of teeth and others an odd number, depending on the module.

Therefore, the arrangement of the pick-ups for even-numbered gears and odd-numbered gears is as follows, assuming that the number of teeth of each gear is N.

(1) For even-numbered gears As shown in Figure 2 or 3, the pitch between pick-ups 1A and 1B and the pitch between pick-ups 2A and 2B are (N/2) + (1/2), respectively. Or, (N/2)-(1/2).

In this case, in order to give priority to canceling the magnetic attraction force of the electromagnetic pickup, both rotating bodies 3 and 4 are
Although the influence of the relative eccentricity remains, there is no practical problem.

(2) For odd number gears As shown in Figure 4, pick ups 1A and 1B
The pitch between the pick-ups 2A and 2B and the pitch between the pick-ups 2A and 2B are both N/2. In this case, the phase difference is 180 degrees in both mechanical and electrical angles.

Next, the operation of this embodiment will be explained.

Each output signal SA1, SA2, SB1, SB2 of each pickup 1A, 1B, 2A, 2B is a sinusoidal alternating voltage.
The phase difference between the output signals SA2 and SB2 of A and 2B is 180 degrees, respectively.

Therefore, the output signals SB1 and SB2 of the compensation pickups 1B and 2B are inverted by the differential amplifiers 15 and 16, and the output signals SA1 and SB2 of the pickups 1A and 2A are inverted.
Add to SA2.

In this way, in this invention, the two pickups 1A and 2A are
B and 2B are placed near opposite sides to reduce torque ripple, and torsion bar 1
The error due to the eccentricity of 0 is also reduced, so the outputs of the pickups 2A and 2B corresponding to the pickups 1A and 1B are sinusoidal voltages,
As a result, these sine wave outputs have electrical angles shifted by 180 degrees. Therefore, the sine wave outputs of pickups 1A and 1B, which are shifted by 180 degrees, are output to differential amplifier 1.
5, and the added sine wave output signal is also doubled.Similarly, the outputs of the sine wave voltages of the pickups 2A and 2B are added by the differential amplifier 16, so the output torque signal S3 is (signal)/
It also becomes resistant to N (noise).

The subsequent signal processing is the same as the conventional one. That is, the output signals S5 and S6 of the differential amplifiers 15 and 16
is shaped by waveform rectifiers 5 and 6, and its phase is determined by a phase discriminator 7, and pulse signals representing phase lead or lag are obtained from output terminals T1 and T2, respectively. If this pulse signal is amplified by a differential amplifier 8 and smoothed by a low-pass filter 9, a DC voltage proportional to the amount of "twisting" of the torsion bar 10 is outputted as a torque signal S.
It can be obtained as 3.

Note that the differential amplifiers 15 and 16 described above are as follows:
If the impedance, voltage, etc. of the pick-up do not interfere with subsequent processing, it may be possible to connect the windings in series with opposite polarities and not use them for each pick-up of the rotating body.

〔Effect of the invention〕

According to this invention, as described above, mechanically
By providing two pickups on each rotating body so that they are arranged at 180 degrees and output phases are shifted by 180 degrees, it is possible to provide a torque detection device that has the following effects.
That is, (1) spurious torque fluctuations synchronized with rotation caused by relative eccentricity of both gears can be canceled out, and high torque detection accuracy can be obtained.

(2) Response characteristics are also improved because signal processing is not performed using a low-pass filter.

(3) Since it is possible to prevent the "torsional" resonance of the torque transmission means in the low speed range, which was caused by the magnetic attraction force of the electromagnetic pickup, the measurement range is expanded, especially in the low speed range, and torque measurement can be performed over a wide speed range. It becomes possible.

[Brief explanation of the drawing]

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. 1A, 1B, 2A, 2B... Pick up,
3, 4... Rotating body, 5, 6... Waveform shaper, 7...
...Phase discriminator, 8, 15, 16...Differential amplifier,
9...Low pass filter, 10...Torsion transmission means, 21...Ferrite magnet, 22...Yoke, 23...Coil.

Claims (1)

[Scope of Claims] 1. A torque transmission means capable of transmitting torque from the drive side to the output side, and N magnetic bodies fixed at regular intervals along the longitudinal direction of the torque transmission means, each having an even number on the outer periphery. at least two rotating bodies provided with protrusions; a pick-up for detecting changes in magnetic flux corresponding to the irregularities of the protrusions of each of the rotating bodies; two pick-ups are provided for each rotating body; N/2)+(1/
2) or torque detecting means arranged at a pitch interval of (N/2)-(1/2) and detecting torque from the phase difference of the output of the pickup corresponding to each of the rotating bodies. Torque detection device. 2. A torque transmission means capable of transmitting torque from the drive side to the output side, and at least N magnetic protrusions fixed at regular intervals along the longitudinal direction of the torque transmission means, each provided with an odd number of N magnetic protrusions on the outer periphery. Two rotating bodies, and a pick-up that detects changes in magnetic flux corresponding to the irregularities of the protrusions of each of the rotating bodies; two pick-ups are provided for each rotating body, and these two pick-ups are arranged at a pitch interval of N/2. A torque detecting device, comprising: a torque detecting means for detecting torque from a phase difference between the outputs of the pickups corresponding to the respective rotating bodies.