JP3081258B2 - Brake failure detection method - Google Patents

Abstract

PURPOSE:To detect brake failure without requiring hardware by detecting the difference of currents to be fed to a motor, respectively, at the time of brake operation and nonbrake operation. CONSTITUTION:Under a state where a motor 21 is stopping and a working coil 25 of a brake shoe 24 is conducting or nonconducting, current to be fed to the motor 21 is increased gradually and a current at the time of starting rotation of the motor 21 is detected through a current detector 31. Difference of rotation starting currents at the time of conducting and nonconducting of the working coil 25 is then calculated and if thus calculated difference is lower than a set value, a decision is made than the brake is faulty.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake failure detecting method, and more particularly to a brake failure detecting method for braking a driving body driven by a motor.

[0002]

2. Description of the Related Art As a conventional brake, for example, a friction brake is known in which a disk is connected to a driving body, and a brake shoe is pressed against the disk to brake the driving body by friction. Widely used for industrial machinery. In such a friction brake, for example, the brake shoe is driven by an operating coil, and the drive of the brake shoe is controlled by switching between energizing and de-energizing the operating coil, that is, by a control circuit including the operating coil. Is known.

On the other hand, in the case of a brake, there has been a brake capable of detecting a failure of the brake in order to prevent an accident or the like beforehand. In this brake, for example, a failure detection circuit constituted by hardware is incorporated in the above-described control circuit. A brake failure is detected by this failure detection circuit. Such a failure detection circuit is shown in FIGS. FIG. 3 shows a circuit for detecting a failure when the brake is braked, and FIG. 4 shows a circuit for detecting a failure when the brake is not braked.

In FIG. 3, an operating coil 1 drives a brake shoe (not shown), and energization and non-energization of the operating coil 1 are controlled by turning on and off a transistor 2. A resistor 3 is provided between the working coil 1 and the collector electrode of the transistor 2. Both ends of the resistor 3 are connected to an input terminal of a differential amplifier 4, and an output terminal of the differential amplifier 4 is connected to a determination circuit 5. It is connected. The determination circuit 5 detects whether or not the working coil 1 is open, that is, whether or not the working coil 1 is disconnected based on the output of the differential amplifier 4.

More specifically, if the operating coil 1 is not disconnected, when the transistor 2 is turned on, the voltage V across the resistor 3 becomes V ₁ , and the differential amplifier 4 sets a predetermined value corresponding to V _1. Output. On the other hand, if the operating coil 1 is disconnected, when the transistor 2 is turned on, the voltage V across the resistor 3 becomes zero, and the output of the differential amplifier 4 becomes almost zero. Therefore, the determination circuit 5 can determine whether or not the operating coil 1 is disconnected by comparing the output value of the differential amplifier 4 with a preset reference value.

In FIG. 4, an operating coil 6 and a transistor 7 have the same functions as the operating coil 1 and the transistor 2 described above. Resistance 8 in parallel with working coil 6
Is connected, and a resistor 9 is connected in series with the operating coil 6 and the resistor 8.
Is connected. The resistance value of the working coil 6 is R,
When the resistance value of the resistor 9 is R ₂ and the resistance value of the resistor 9 is R ₃ , R
≫R ₂ and R ₃ . Potential V between resistance 8 and resistance 9
_o is input to the determination circuit 10, and the determination circuit 10 detects whether or not the working coil 6 is disconnected based on the potential V _o .

[0007] Specifically, if operating coil 6 is not broken, when turning off the transistor 7, the potential V _o to be input to the decision circuit 10 becomes V _o = V _SS. On the other hand, if operating coil 6 if disconnected, when turning off the transistor 7, the potential V _o to be input to the decision circuit 10 is V _o = V
_SS (R ₃ / (R ₂ + R ₃ )). Therefore, the determination circuit 10 can determine whether the operating coil 6 is disconnected by comparing the potential Vo with a preset reference value.

Note that the determinations in the determination circuits 5 and 10 may be executed by software instead of hardware.

[0009]

However, in such a conventional brake failure detection, a brake failure is detected by a failure detection circuit as shown in FIGS. 3 and 4 incorporated in a brake control circuit. Therefore, when a plurality of motors are driven by one control circuit, there is a problem that hardware is increased and cost is increased.

Accordingly, the present invention provides a method for controlling a motor to be driven by a motor while the brake is being driven by a motor and the current supplied to the motor is gradually increased during brake braking and during non-braking. detecting a current value of, by comparing the difference between the detected current value to the setting value corresponding to the brake torque, without using hardware such as a dedicated circuit for output brake late Sawaken, the failure detection of the brake The goal is to make it possible and reduce costs.

[0011]

Means for Solving the Problems] To solve the above Symbol object, a first aspect of the present invention, fault detection of a brake for braking by the energized or de-energized the driving member driven by the motor to the actuating coil a method, in the driven body non-braking state motor is stopped, a first step of detecting a current value at the start rotation of the motor while gradually increasing the current supplied to the motor, the motor is stopped the drive Body control
A second step of detecting a current value at the start of rotation of the motor while gradually increasing the current supplied to the motor in the moving state ;
A third step of comparing the difference between the detected current value at the start of rotation of the motor in the first step and the detected current value at the start of rotation of the motor in the second step with a set value corresponding to the brake torque. It is characterized by doing. Claim
The invention described in claim 2 is the invention according to claim 1, wherein
The non-braking state of the driver is obtained by energizing the working coil.
It is characterized by that. The invention according to claim 3
The invention according to claim 1, wherein the non-braking of the driving body
The state is obtained by de-energizing the working coil
It is assumed that. The invention according to claim 4 is the invention according to claim 1.
In the invention described above, the braking state of the driving body is determined by an operating coil.
Characterized by being obtained by energization.
The invention according to claim 5 is the invention according to claim 1,
The braking state of the driver is obtained by de-energizing the operating coil.
It is characterized by being able to.

[0012]

According to the present invention, in the first step, the current value at the start of rotation of the motor when the motor is stopped and the driving body driven by the motor is in the non-braking state is detected, and in the second step, the motor is stopped. Then, a current value at the start of rotation of the motor when the driving body is in the braking state is detected, and the third step is used to calculate the current value detected in the first step and the current value detected in the second step. The difference is compared with a set value corresponding to the brake torque. Therefore, when the difference between the detected current values in the first and second steps becomes larger than the set value in the third step, a brake failure is detected.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 and 2 are views showing one embodiment of a brake device to which a brake failure detection method according to the present invention is applied. First, the configuration will be described.

In FIG. 1, reference numeral 21 denotes a motor for driving a driving body 22. The driving body 22 is brought into a braking state by pressing a pair of brake shoes 24 against a brake disk 23 connected to a driving shaft of the motor 21. . The driving body 22 is
The brake shoe is pressed against the brake disc 23
The non-braking state is caused by the absence. Brake shoes 24
Is pressed against the brake disc 23 by energizing the operating coil 25. Conversely, the brake shoe 24 may be pressed against the brake disk 23 by de-energizing the operation coil.

A voltage from a power supply 26 can be applied to the operation coil 25, and the application of this voltage is turned on / off by a brake switch 27. The motor 21 is driven by a DC power supply 28. The current supplied to the motor 21 can be slightly increased or decreased by the controller 29, and can be turned on / off by the motor switch 30. The current supplied to the motor 21 is detected by a current detector 31, and the rotational position and the torque of the motor 21 are detected by a rotational position detector 32 and a torque detector 33, respectively. The brake switch 27, the controller 29, the motor switch 30, the current detector 31, the rotational position detector 32, and the torque detector 33 are connected to a control unit 34 composed of a microcomputer or the like. To control the driving of the driving body 22 and the brake braking. In addition, the control unit 34 executes a program stored in a ROM (Read Only Memory) (not shown) or the like, and detects a failure of the brake according to a procedure described later shown in FIG.

Next, a brake failure detecting procedure according to this embodiment will be described with reference to a flowchart shown in FIG. In addition,
S ₁ to S ₂₁ in FIG. 2 shows the steps of the flowchart. In S _1, a brake switch 2 at the motor stop state
Released brake 7 by turning off the at S _2, is slightly the current supplied to the motor 21 by operating the controller 29. In S _3, current detector 3 a current value supplied to the motor 21
Reading 1, in S _4, it reads the rotational position of the motor 21 from the rotational position detector 32. In S _5, | detected current value |> I _L1
Whether the (however, I _L1 reference value of the overcurrent which is set in advance) to determine, | detected current value |> If I _L1, i.e., when an overcurrent flows through the motor 21, the S ₆ Proceed to make a failure determination due to brake seizure.

On the other hand, unless | detected current value |> _IL1
Proceeds to S _7, it is determined whether or not the rotational position of the motor 21 is changed. If the rotational position has not changed, the process returns to S _2,
If the change, the process goes to S _8. In S _8, the current value supplied to the motor 21, i.e., the current value I ₁ at the start of the motor rotation
Reading from the current detector 31, in S _9, the motor switch 3
0 is turned off to stop the motor 21. In S _10, to actuate the brake to turn on the brake switch 27, S
_{In step 11} , the motor switch 30 is turned on to operate the controller 29 to slightly increase the current supplied to the motor 21. S
_12, reads the current value supplied to the motor 21 from the current detector 31, in S _13, reads the rotational position of the motor 21 from the rotational position detector 32.

[0018] In S _14, | detected current value |> I _L2 whether the (however, I _L2 is set reference value of the overcurrent advance) to determine, | detected current value |> If I _L2, That is, the motor
If an overcurrent flows to 21, the process proceeds to S _15, make a failure determination according to seizing of the brake. On the other hand, | detected current value |> I
_L2 Otherwise, the process proceeds to S _16, and determines whether or not the rotational position of the motor 21 is changed. If the rotational position has not changed, the process returns to S _11, if the change, the process proceeds to S _17. S
_17, a current value supplied to the motor 21, namely, reads the current value I ₂ at the start of the motor rotation from the current detector 31,
In S _18, it stops the motor 21 by turning off the motor switch 30.

In S19, the difference between I ₁ and I ₂ , that is, the difference between the motor starting current I ₁ when the brake is released and the motor starting current I ₂ when the brake is applied is equivalent to the brake torque. To the set value to be set, specifically, | I
_It is determined whether or not ₁₋ I ₂ |> I _S. However, I _S is the threshold, is set to be smaller in consideration of an error or the like than the value corresponding to the brake torque. | I ₁
-I ₂ | if> a I _S, the process proceeds to S _20, verdicts brake is normal. On the other hand, if | I ₁ −I ₂ |> I _{S is} not satisfied, the routine proceeds to S _{21, in} which a determination is made that a brake has failed due to disconnection of the working coil 25 or that the brake shoe 24 needs to be replaced. Specifically, when the brake is normal, | I ₁ −I ₂
Is substantially equivalent to the brake torque, which is larger than I _S , and when the working coil 25 is disconnected, the difference between I ₁ and I ₂ becomes almost zero, and the brake shoe 2
Even if 4 is worn and the brake torque is drastically reduced,
Since the difference between I ₁ and I ₂ is almost zero, S ₂₀ and S ₂₁
Thus, the above-described determination can be made.

As described above, in this embodiment, in S _{1 to} S ₃ and S ₅ , the current supplied to the motor 21 while the motor 21 is stopped and the brake is released is gradually increased, and the detected current value and the overcurrent comparing the magnitude of the I _L1 criteria, whereas, S ₉
In to S ₁₂ and S _14, and gradually increasing the current supplied to the motor 21 in a state of being energized to the operating coil 25 stops the motor 21, so that by comparing the magnitude of the detected current value and I _L2, respectively When the detected current value becomes larger than I _L1 and I _L2 , it can be detected as occurrence of a mechanical failure of the brake due to seizure between the brake shoe 24 and the brake disk 23. In S ₄ , S ₇ and S ₈ , the motor 2
1, the current value I ₁ at the start of rotation is detected, and at S ₁₃ , S ₁₆ and S ₁₇ , the current value I ₂ at the start of rotation of the motor 21 is detected,
In S _19, | because it compares the magnitude of which is set corresponding to the brake torque equivalent value _{I S, | | I 1 -I} 2 I 1 -
When I ₂ | becomes larger than I _S can be detected as the occurrence of a failure due to the disconnection of the working coil 25 and the time for replacing the brake shoe 24. Further, the failure detection of the brake as described above is performed by using the existing configuration of the brake device, that is, the brake switch 27, the controller 29, the motor switch 30, the current detector 31, the rotational position detector 32, the control unit 34, and the like. Therefore, hardware such as a dedicated circuit for detecting a brake failure can be made unnecessary, and the cost can be reduced.

Although the present embodiment has been described with reference to the case where the brake is operated by energizing the operating coil 25, the brake switch 27 is also operated when the operating coil 25 is de-energized. It is needless to say that the same operation and effect as in the present embodiment can be obtained only by reversing the on / off operation.

[0022]

According to the present invention, the current values at the start of each motor rotation are detected by the first to third steps while gradually increasing the current supplied to the motor during braking and non-braking, Since the difference between the detected current values is compared with a set value corresponding to the brake torque, a brake failure can be detected without using hardware such as a dedicated circuit for brake failure detection, thereby reducing costs. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a brake device to which a brake failure detection method according to the present invention is applied.

FIG. 2 is a flowchart illustrating an example of a detection procedure of a brake failure detection method according to the present invention.

FIG. 3 is a circuit diagram showing a conventional brake failure detection circuit.

FIG. 4 is a circuit diagram showing another conventional brake failure detection circuit.

[Explanation of symbols]

 21 Motor 22 Driver 23 Brake disc 24 Brake shoe 25 Operating coil 27 Brake switch 29 Controller 30 Motor switch 31 Current detector 32 Rotational position detector 34 Control unit

Claims (5)

(57) [Claims] 1. A method for detecting a failure of a brake for braking by energizing or de-energizing a driving body driven by a motor to an operating coil, wherein the motor is stopped and the driving body is in a non-braking state. A first step of detecting the current value at the start of rotation of the motor while gradually increasing the supplied current; and starting the rotation of the motor while gradually increasing the current supplied to the motor when the motor is stopped and the driving body is in the braking state. And a setting corresponding to a brake torque, wherein a difference between the detected current value at the start of rotation of the motor in the first step and the detected current value at the start of rotation of the motor in the second step is determined. And a third step of comparing the value with a value. 2. The non-braking state of the driving body includes a
2. The method according to claim 1, wherein the current is obtained by energization.
Brake failure detection method. 3. The non-braking state of the driving body includes the operation coil
2. The method according to claim 1, wherein the current is obtained by de-energization.
Brake failure detection method. 4. The braking state of the driving body is determined by the operation coil
2. The buoy according to claim 1, wherein the buoy is obtained by electricity.
Rake failure detection method. 5. The braking state of the driving body is determined by a non-operational state of the operating coil.
2. The method according to claim 1, wherein the current is obtained by energization.
Brake failure detection method.