JPS6325214B2 - - Google Patents

Description

Detailed Description of the Invention The present invention provides a motor that constantly operates at high speed by energizing a built-in clutch coil to press and engage a clutch friction member provided on the motor shaft and a clutch lining provided on the output shaft side. The present invention relates to an electromagnetic drive device having an electromagnetic clutch mechanism that transmits rotational force of the clutch lining to an output shaft, and detects a wear amount of the clutch lining.

Conventionally, a drive device having the electromagnetic clutch mechanism described above has been used for driving a sewing machine, for example, and when the clutch lining wears out and the coupling member carrying the clutch lining comes into contact with the clutch friction member, the output power decreases. The speed of the shaft became unstable, or metal came into contact with metal at the pressure welding part, resulting in meshing, making speed control impossible, and in some cases, rotating at high speed and being unable to stop, which was dangerous. In addition, as mentioned above, the temperature rises significantly due to the contact between metals, which is dangerous.On the other hand, the clutch friction member may be damaged due to the contact between metals, which may require repair. There were also problems.

However, the current situation is that no countermeasures have been taken to address the above-mentioned drawbacks.

The present invention aims to provide a safe electromagnetic drive device by detecting the above-mentioned wear margin before metals come into contact with each other, eliminating the above-mentioned dangers or problems.

FIG. 1 shows the configuration of an electromagnetic clutch motor. A flywheel 1 is fixed to a motor shaft 2 and constantly rotates at high speed. The clutch friction portion 3 made of magnetic metal is fixed to the flywheel 1, and forms a magnetic circuit shown by broken lines between the clutch fixing iron core 4 and the clutch connecting member 5 made of magnetic metal, and the clutch coil 6 produces a magnetic flux φ _A. The clutch lining 7 is usually made of cork and is adhered to and carried by the clutch connecting member 5. The clutch connecting member 5 is movable on a spline shaft 9 fixed to the output shaft 8, with the thrust direction being free and the rotational direction being fixed.

A brake mechanism consisting of a brake coil 10, a brake iron core 11, a brake friction member 12, a brake lining 13, and a brake connecting member 14 is arranged symmetrically to the clutch mechanism, and when the brake coil 10 is excited, φ _B
A magnetic flux is generated as shown by the broken line.

The operation configured as described above is performed as follows.

When the clutch coil 6 is excited, the magnetic flux φ _A
occurs, the clutch connecting member 5 moves toward the clutch friction member 3 that constantly rotates at high speed, the clutch lining 7 is pressed into engagement, and the rotational force of the clutch friction member 3 is transmitted through the clutch connecting member 5 and the spline shaft 9. is transmitted to the output shaft 8, and the output shaft 8 is rapidly accelerated.

On the other hand, when the speed increases above the set speed, the brake coil 10 is excited, a magnetic flux φ _B is generated as shown by the broken line, the brake connecting member 14 moves toward the brake friction member 12, and the brake lining 13
The static force is transmitted to the output shaft 8 via the spline shaft 9, and the output shaft 8 is decelerated.

In this way, a predetermined speed can be obtained, but in normal stable operating conditions, the excitation force of the clutch coil 6 is adjusted, and therefore the magnetic flux φ _A is adjusted to increase the speed at the surface of the clutch lining 7. The operation is performed so that a constant speed is maintained by adjusting the pressure contact force and creating an appropriate slippage.

As mentioned above, since the clutch lining 7 constantly slides on its surface and its speed is controlled, wear is inevitably accelerated, and eventually the height of the clutch lining 7 from the end surface of the clutch friction member 5 increases.
When G _C becomes 0, the clutch friction member 3 and the clutch connecting member 5 come into direct contact, which generates heat and creates a dangerous situation as described above. There was a risk of an abnormal situation, such as a loss of information.

In the present invention, a predetermined wear amount of the clutch lining 7 is detected before entering the abnormal state,
This is to prevent the dangerous situation mentioned above.

Here, wear of the brake lining 13 accelerates as well, but since the other brake friction member 12 that is press-fitted is always stationary, there is no danger, or as mentioned above, the intermediate speed operation is usually performed on the clutch side. The object of the present invention can also be achieved by a method of detecting only a specified wear amount of the clutch lining 7, since the clutch lining 7 wears out more quickly than the clutch lining 7. An example of this will be explained below using FIGS. 2 to 5.

In FIG. 2, 15 is a control circuit, which is composed of a logic IC circuit centered on a microcomputer. 16
is a pulse generator, which is mainly composed of a monostable multivibrator, and outputs a pulse width set by the control circuit 15. 17 is a driver for driving the clutch coil 6 built into the motor 18, 19 is a current measuring circuit, and 20 is a comparator.

FIG. 3 shows an example of a configuration that further embodies the above configuration, and in particular, the control circuit 15 and pulse generator 16 are configured by a one-chip microcomputer 21 (hereinafter referred to as microcomputer).

Furthermore, FIG. 4 shows a time chart of the operation.

In FIG. 3, +V represents the DC power supply voltage for driving _{the DD} clutch coil 6, and +V _CC represents the DC stabilized power supply voltage for driving the IC circuit. Further, 21 is the control circuit 15 and the pulse generator 1 as described above.
IC1 is an inverter IC which drives the clutch coil 6 by switching the transistor TR1 through the diode D1. Note that the diode D2 and the resistor R1 are a flywheel circuit for suppressing the abnormal voltage generated at the collector when the transistor TR1 is turned off and protecting the transistor.

The voltage across the resistor R2 connected to the emitter of the transistor TR1 is the voltage across the resistor R2 connected to the emitter of the transistor TR1.
1 changes in proportion to the current flowing through the clutch coil 6 when the clutch coil 6 is turned on. The resistance R2 and the resistance R
3, R4, R5 and the OP amplifier IC and IC2 constitute the current measuring circuit 19, which amplifies the signal representing the coil current to a required level and outputs the signal.
Va is output.

Also, resistors R6, R7, R8, variable resistor VR1,
and IC3 of the OP amplifier IC constitute the comparator 20, and when the signal Va reaches the voltage Vc set by the variable resistor VR1, the output of the IC3
Vb is inverted.

The clutch connecting member 5 configured as described above
The height of the clutch lining 7 from the end face of
The operation for detecting G _C , that is, the amount of wear on the clutch lining 7, is as follows.

First, the control circuit 15 instructs the pulse generator 16 to generate a pulse having a time width T1, and the pulse generator 16, through the driver 17, excites the clutch coil 6 for the time T1. This time T1 is set as the time required for the clutch lining 7 to come into contact with the clutch friction member 3.

Next, after waiting for a time T2 when the clutch coil current stops flowing through D2 and R1 of the flywheel circuit, the same process as above is performed for a time T2.
energizes the clutch coil 6. The time T
After lapse of time, the microcomputer 21 changes the signal Vb to “high level”
If it is, it is determined to be "normal", and if it is at a "low level", it is determined to be "amount of wear is large".

The principle of detecting the amount of wear on the clutch lining 7 described above is as follows. That is, the inductance L of the clutch coil 6 changes in proportion to the vermeance P of its magnetic circuit, and the permeance P changes greatly in accordance with changes in the gap distance unless there is magnetic saturation in the iron core. In other words, the wear of the clutch lining 7 progresses and the clutch friction member 3
As the gap between the clutch connecting member 5 and the clutch connecting member 5 becomes smaller, the permeance P becomes larger, and the inductance L changes to become larger. On the other hand, the time constant τ, which is a measure of the rise time of the excitation current of the clutch coil 6, is expressed by τ=L/R, and since the series resistance R in this equation is constant, it can be said that τ is proportional to the inductance L.

Therefore, in a state in which the height G _C of the clutch lining 7 from the end face of the clutch connecting member 5 to be detected is set using a jig or the like, the signal after the elapse of time T is determined in advance as shown by the chain line in FIG.
If Va is set to match the reference voltage _VC , it will be possible to detect when wear accelerates and reaches the specified value during normal use.

FIG. 5 shows a flow chart of the operation of the microcomputer 21 mentioned above. At step 22, a pulse signal for excitation of the dummy clutch coil 6 is generated for a time T1 to move the clutch lining 7 into contact with the clutch friction member 3, and then the current in the clutch coil 6 becomes approximately zero. Wait for the time T2.

At step 23, the clutch coil attraction signal of time T is generated in order to actually measure the height G _C of the clutch lining 7 from the end face of the clutch connecting member.

At step 24, the signal Vb is checked, and if it is at a "high level" it is determined to be normal, otherwise it is determined that there is a large amount of wear, and the subsequent operation is stopped.

Here, when the clutch coil 6 is excited for a time T1 or T, a phenomenon occurs in which the output shaft 8 rotates slightly _. The present invention can be more effectively realized by using a method of exciting the brake coil 10.

Further, normally the wear of the lining 7 does not occur rapidly, so the determination is made once immediately after the power is turned on, and thereafter the control circuit 15 directly drives the clutch coil 6 via the driver 17. It can be said that this method is one effective means for realizing the present invention.

As described above, the present invention first provides a so-called dummy section in which the clutch coil is excited for time T1 and then waits for time T2, and after initializing the magnetic circuit, the clutch lining 7 is raised. The change in _permeance caused by the change in the clutch lining 7 is interpreted as a change in the inductance of the coil, and therefore, by detecting the change in the time course of the excitation current to the clutch coil after a predetermined time T, the height of the clutch lining 7 can be determined. According to the present _invention , it is possible to prevent dangers caused by heat generation or runaway of the output shaft as in the past, and since it can be detected before the surface of the clutch friction member is damaged, it can be easily detected during service. This is advantageous and has a great effect in that it can be provided at low cost with a simple circuit configuration.

[Brief explanation of drawings]

Figure 1 is a sectional view of the electromagnetic clutch motor, Figure 2 is a cross-sectional view of the electromagnetic clutch motor.
The figure is a block diagram of the electromagnetic drive device of the present invention, FIG. 3 is a circuit diagram of the wear detection means used in the device, FIG. 4 is an explanation diagram of the operation of the same circuit, and FIG. 5 is an explanation diagram of the operation of the wear detection. be. 2...Motor shaft, 3...Clutch friction member,
4... Fixed iron core, 5... Clutch connection member, 6...
...Clutch coil, 7...Clutch lining,
8... Output shaft, 15... Control circuit, 16... Pulse generator, 17... Driver, 18... Motor, 19... Current measurement circuit, 20... Comparator.

Claims (1)

[Scope of Claims] 1. A motor that constantly operates at high speed, a clutch friction member made of magnetic metal disposed in a part of the motor, and a clutch disposed on an output shaft and located opposite to the clutch friction member. A fixed iron core is arranged with an appropriate gap between the clutch connecting member carrying the lining and the clutch friction member, and a magnetic path is formed between the clutch friction member and the fixed iron core in the center of the fixed iron core. The coil is arranged in such a way that the clutch connecting member and the clutch connecting member are pressed into engagement through the clutch lining by energizing the coil, and the coil is arranged so as to transmit the rotational force of the motor to the output shaft. The wear detection means includes a control means for exciting, and a wear detection means for detecting a wear amount of the clutch lining, and the wear detection means includes a pulse generation means for generating a pulse signal for a predetermined time T in accordance with a command from the control means; Consisting of a driver that excites the coil for a time T, a current measuring means that measures the current value to the coil, and a comparator that compares the current measurement result after the elapse of the time T with a specified value, The electromagnetic drive device is configured such that, based on the comparison result after the elapse of the time T, the control means performs a wear detection operation such that the wear amount of the clutch lining is detected by a predetermined amount or more. 2 Based on a command from the control means, the pulse generation means first generates a pulse signal T1, and during this pulse signal T1, the coil is excited by the driver, and then, after a time period T2 has elapsed, the wear detection is performed. An electromagnetic drive device according to claim 1, which is configured to operate.