JP2633115B2 - Zero compensation device for torque sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zero correction device for a torque sensor.

[0002]

2. Description of the Related Art As a means for detecting the magnitude of a torque applied to a torque transmission shaft, for example, a magnetostrictive torque sensor is known from Japanese Patent Application Laid-Open No. 1-138443. In this magnetostrictive torque sensor, a pair of magnetic anisotropic parts are provided on the outer peripheral surface of a torque transmission shaft so as to be inclined in opposite directions to each other, and an exciting coil and a pair of detecting coils are provided around these magnetic anisotropic parts. What is provided is general.

In this type of torque sensor, as shown by a solid line in FIG. 4, a detection signal proportional to the magnitude of the torque applied to the shaft is obtained, and in a normal state, when the applied torque is zero. The output is also zero.

[0004]

However, when the ambient temperature of the sensor or the excitation detection circuit changes, the detection characteristic fluctuates as shown by a broken line in FIG. 4, and an output A occurs when the torque is zero. There is a problem that zero point fluctuation occurs and causes a detection error.

Accordingly, an object of the present invention is to solve such a problem and to make it possible to easily and surely correct a zero point in a torque sensor.

[0006]

In order to achieve the above object, the present invention provides a shaft rotation detecting sensor for detecting whether or not a torque transmitting shaft is rotating, and a method for applying a torque to the torque transmitting shaft.
The rotation signal from the shaft rotation detection sensor
At a second delay longer than the first delay time before being applied
Means for delaying the torque detection signal only during
The torque transmission shaft is not rotating by the detection sensor
Is delayed by the second delay time when
The acquired torque detection signal is captured and stored as zero point data.
Holding means for holding, when the signal during rotation is output,
Stop the acquisition of zero point data by the holding means, and
The zero point data immediately before the stop of
Means, and the zero point data held by the holding means.
After that, the torque detection signal without delay is set to zero.
Correction means and release of torque to torque transmission shaft
The rotation signal from the shaft rotation detection sensor disappears
Until the delay torque detection signal from the delay means disappears.
A fourth delay time longer than the third delay time in
And a torque detection signal after the elapse of the fourth delay time.
The zero correction of the signal is stopped, and the zero
Means for resuming data acquisition and retention .

[0007]

[0008]

With this configuration, it is possible to detect that the torque transmission shaft is not rotating, that is, that the torque transmission shaft is in a zero torque state, by the shaft rotation detection sensor. Therefore, the torque detection signal at that time is captured and held as a detection signal when the torque is zero, that is, zero point data.
When torque is applied to the torque transmission shaft and rotation starts,
The torque detection signal at that time is corrected to zero using the stored zero data. As described above, the zero point data is constantly corrected when the torque is zero, and the zero point correction is performed with the zero point data immediately before the applied torque is detected.
A torque signal with little zero point fluctuation can be obtained.

In the shaft rotation detecting sensor, a detection time delay is generally caused as compared with the state of torque application to the shaft. However, the operation of the delay means causes a torque detection signal not to appear yet. By stopping the capturing and holding of the zero point data at the time when the rotating signal is output, and restarting the capturing and holding after the elapse of the fourth delay time after the torque detection signal disappears, the time is reduced. Zero point data is obtained after the influence of the delay is removed and the influence of the torque applied to the shaft is reliably removed.
During torque application, a delay is applied by the zero point correction means.
Real-time torque detection signal without delay
After the signal is zero-corrected, the final output is output.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes a torque transmission shaft, and a pair of magnetically anisotropic parts 2, 2 inclined in opposite directions are formed on the outer peripheral surface thereof. An excitation coil 3 and a pair of detection coils 4, 4 provided corresponding to the magnetic anisotropic parts 2, 2 are provided around the magnetic anisotropic parts 2, 2. The excitation coil 3 is connected to an AC excitation power supply 5. Rectifier circuits 6, 6 and filters 7, 7 are connected in series to the respective detection coils 4, 4, and both filters 7, 7 are connected to a subtraction point 8. Subtract 8 is A
It is connected to the / D converter 9.

An output line 10 from the A / D converter 9 is connected to a digital operation control circuit 11 and a delay circuit 12. The output line 13 of the delay circuit 12 is also an arithmetic control circuit.
Connected to 11. On the other hand, a shaft rotation detection sensor 14 for detecting whether or not the torque transmission shaft 1 is rotating is provided corresponding to the torque transmission shaft 1. The output line 15 of the shaft rotation detection sensor 14 is also
It is connected to the.

FIG. 2 shows a detailed structure of the arithmetic control circuit 11. An output line 10 from the A / D converter 9 is connected to a subtraction point 18, and an output line 13 from the delay circuit 12 is connected to a switch 19.
Is connected to a zero point memory 20 for storing data for zero point correction. The output line of the zero point memory 20 is
It is connected to a subtraction point 18 and another subtraction point 21. Subtraction point
The output line 13 is directly connected to 21. Subtract 18
Are connected to a final output line 24 via a switch 23 having a knot circuit 22. The subtraction point 21 is the switch 25
And is connected to the final output line 24 via.

An output line 15 from the shaft rotation detecting sensor 14 is connected to a first signal processing circuit 26, which outputs a binary signal indicating whether or not the shaft 1 is rotating. During rotation is generated. First signal processing circuit
The output side of 26 is connected in parallel to an output line 27 for outputting the in-rotation signal d and a second signal processing circuit 28. The in-rotation signal d appearing on the output line 27 is used for purposes such as monitoring the rotation of the shaft 1. Second signal processing circuit 28
Generates a data correction in-progress signal e by performing a process described later on the in-rotation signal d. An output line 29 from the second signal processing circuit 28 is connected to switches 19 and 25 and a switch 23 having a knot circuit 22.

Next, the operation will be described. On the output line 10 from the A / D converter 9, a torque detection signal a similar to that shown by the solid line in FIG. 4 appears. The shaft 1 is a shaft to which a torque is applied so that the rotation is performed intermittently, such as a rotating torque tester of a motor or a screw tightening machine. , As shown in FIG.

The torque detection signal a is shifted by the time T1 in the delay circuit 12, and the time-shifted delay signal b
Is output from the delay circuit 12. Meanwhile, the shaft rotation detection sensor
The in-rotation signal d obtained by processing the detection signal from 14 by the first signal processing circuit 26 is, as shown in FIG.
It has a characteristic that the time when the rising portion occurs is delayed by the time T2 from the time when the torque is actually applied to the shaft 1. Therefore, the data shift time T1 is T1
> T2. Data correction signal e generated from the rotation signal d by the second signal processing circuit 28
Switches from on to off at the time of the rise of the rotating signal d. On the output side of the knot circuit 22, an inverted signal obtained by inverting the signal e during data correction appears.

That is, in the arithmetic and control circuit 10 shown in FIG. 2, when the torque is zero, the in-data correction signal e is turned on, so that the switches 19 and 25 are closed.
The switch 23 connected to is opened. For this reason, the delay signal b from the delay circuit 12 is inputted and stored in the zero point memory 20 as zero point data for correcting the zero point of the torque detection signal, and is outputted from the zero point memory 20 and inputted to the subtraction point 21. You. As a result, the zero point data is constantly corrected and updated by the delay signal b input to the zero point memory 20. On the other hand, since the delay signal b is inputted to the subtraction point 21 as it is, a zero signal is eventually output from the subtraction point 21 and this is output as the torque signal c as the final output line 24.
Sent out to

When a torque is applied to the shaft 1, the data correction signal e is turned off with a delay of time T2, and the switches 19 and 25 are turned off.
Is opened and the switch 23 is closed, and the correction of the zero point data is stopped. At this time, since the relationship of T1> T2 is established as described above, immediately before the correction of the zero point data is stopped, although the torque is already applied to the shaft 1, the output line 13 does not appear, preventing the zero point data in the zero point memory 20 from being adversely affected.

When the signal e during data correction is turned off,
The current torque detection signal a with no time delay and the zero point data from the zero point memory 20 are input to the subtraction point 18. Then, a torque signal c obtained by zero-correcting the torque detection signal a with the zero-point data is output to the final output line 24.

As shown in FIG. 3, when the torque applied to the shaft 1 is released, the rotation signal d is turned off after a lapse of a certain delay time, and the time T3
, The delay signal b becomes zero in torque. The data correction signal e turns on after a lapse of time T4 after the rotation signal d turns off. Here, the time T4 is determined so that T4> T3.

In this manner, the correction of the zero point data is started again. However, since the relationship of T4> T3 is established as described above, when the correction of the zero point data is restarted, the output line 13 is reset. The signal is reliably zero, and in this case also, the zero data in the zero memory 20 is prevented from being adversely affected.

[0021]

As described above, according to the present invention, when the torque transmitting shaft is not rotating but is in the state of zero torque ,
Zero point data can be obtained and the torque detection signal is appropriate
Not only can zero point be corrected,
Sometimes zero data can be constantly corrected. Also
According to the present invention, the shaft rotation is compared with the state of torque application to the shaft.
Function of the delay means even if the output of the rotation detection sensor is delayed.
Can further delay the torque detection signal.
Therefore, the torque detection signal at the time of torque application appears.
In the meantime, when the torque is not yet applied to the shaft
The torque detection signal of
After that, the acquisition and holding of the zero data is stopped.
Can be stopped and after the torque detection signal disappears
After the elapse of the fourth delay time, the acquisition and holding are repeated.
Can be opened, the torque applied to the shaft and the shaft rotation detection
The effect of the time lag with the sensor output can be removed,
Therefore, the effect of the torque applied to the shaft is reliably eliminated.
It is possible to obtain the zero data that has been deleted. Also applied torque
Zero can be corrected with the zero data just before detecting
A torque signal with little point fluctuation can be obtained. further
According to the present invention, during torque application, the zero point correcting means
Real-time with no delay and therefore no time delay
Outputs final output after zero correction of torque detection signal
Can be done.

Further, according to the present invention, before the torque detection signal has yet appeared by the operation of the delay means, the acquisition and holding of the zero point data are stopped at the time when the rotating signal is output, and the torque detection signal is output. The fourth after disappearing
After the delay time elapses, the capturing and holding are resumed, so that the influence of the time delay can be removed, and the zero point data can be corrected by reliably removing the influence of the torque applied to the shaft.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an apparatus for correcting a zero point of a torque sensor according to an embodiment of the present invention.

FIG. 2 is a detailed circuit diagram of an arithmetic control circuit in FIG.

FIG. 3 is an operation explanatory diagram of each unit in the circuits of FIGS. 1 and 2;

FIG. 4 is an explanatory diagram of zero point fluctuation of a conventional general torque sensor.

[Description of Signs] 1 Torque transmission axis 11 Arithmetic control circuit 12 Delay circuit 14 Axis rotation detection sensor 19 Switch 20 Zero memory 23 Switch 25 Switch a Torque detection signal b Delay signal c Torque signal d Rotating signal e Data correction Medium signal

Claims (1)

(57) [Claims] 1. A torque sensor for detecting the magnitude of torque applied to a torque transmission shaft, wherein: a shaft rotation detection sensor for detecting whether the torque transmission shaft is rotating ; Has torque been applied to the transmission shaft?
Until the in-rotation signal is output from the shaft rotation detection sensor.
Delay time longer than the first delay time (T2) at
Means (12) for delaying the torque detection signal by (T1),
The torque transmission shaft is rotating by the shaft rotation detection sensor
At the time of the second delay
The torque detection signal delayed by (T1)
Holding means (20) for capturing and holding, and a signal during rotation
At the point when the zero point data is output by the holding means (20).
Data acquisition is stopped and the zero point data immediately before the stop
Means (19) for holding the object by the holding means;
Zero data held by the holding means (20)
A procedure for zero-correcting the torque detection signal without delay
Step (18), the application of torque to the torque transmission shaft is released
Before the rotation signal from the shaft rotation detection sensor disappears
Until the delay torque detection signal from the delay means disappears.
The fourth delay time (T4) longer than the third delay time (T3)
Means (28) for setting the fourth delay time (T4)
After the lapse of time, the zero point correction of the torque detection signal is stopped, and the
The capture and holding of zero point data by the holding means is restarted.
Means (19) for adjusting the zero point of the torque sensor.