JP2559109Y2 - Brake lining wear detector - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake lining wear detecting device for detecting when a brake lining is worn to a predetermined amount or more, for example, to a wear limit in a friction brake such as a drum brake, a disc brake or the like.

[0002] In a friction brake, if the brake lining wears beyond the wear limit, there is a problem that the brake becomes less effective. For this reason, in a vehicle having such a brake, when the brake lining has worn down to the wear limit, a device has been devised which detects this and alerts the driver. Examples of such an apparatus include those disclosed in Japanese Utility Model Publication No. 2-19639 and Japanese Utility Model Publication No. 2-19640.

The wear detecting devices disclosed in these publications detect wear of a brake lining (brake pad) in a disc brake, and a wear detecting tool having a metal wire therein is disposed at a predetermined position. When is worn to the wear limit, a rotor or the like comes into contact with the wear detection tool. When the rotor or the like comes into contact with the wear detector, the wear detector is cut off at that part and the internal metal wire is cut, and this cut is detected by interrupting the current flowing through the metal wire, It detects the wear of the brake lining.

[0004]

Here, the above wear detecting device is used for a disc brake, and it is difficult to use the same for a drum brake due to problems such as heat resistance of a wear detecting tool and wiring. There is. When the above-mentioned wear detecting device is used for the drum brake, a wear detecting device is provided in the brake drum. However, since the inside of the brake drum becomes high temperature due to frictional heat generated when the brake is operated, the wear detecting device is used. The coating of the wiring connected to the metal wire may be melted and short-circuited. If the wiring connected to the metal wire is short-circuited in this way, even if the brake lining wears to the wear limit and the wear detector comes into contact with the rotor, etc., and the wear detector is cut off and the internal metal wire is cut, Since the current flows through the short-circuit portion, there is a problem that the wear of the brake lining cannot be detected.

In the above wear detecting device, a current is always supplied to the metal wiring of the wear detecting tool, and when the metal wiring is cut, this is detected from a change in the current. For this reason, if the current stops flowing through the metal line of the metal detector due to an abnormality of the wiring line that supplies the current to the wear detector (for example, an abnormality such as disconnection of the wiring line or poor contact), an error occurs. Therefore, there is a problem that a warning that the brake lining is worn is issued. That is, in the above wear detection device, when the current flowing through the metal wire of the wear detection tool is interrupted, is it due to the wear of the brake lining, or the abnormality such as disconnection of the wiring line or poor contact? There is a problem that cannot be determined.

The present invention has been made in view of the above-described problems, and can be easily used for both a drum brake and a disc brake. When the brake lining is worn, this can be detected and an alarm can be issued. An object of the present invention is to provide a brake lining wear detection device having such a configuration. Another object of the present invention is to provide a brake lining wear detection device configured to be able to detect an abnormality such as a disconnection of a wiring line for detecting brake lining wear separately from the lining wear detection. I do.

[0007]

In order to achieve the above object, according to the present invention, in a friction brake comprising a lining member provided with a brake lining and a brake member against which the brake lining is pressed when a brake is operated, A wear detection sensor is attached to one of the lining member and the brake member, and the wear detection sensor comes into contact with the conductive ground member when the brake lining is pressed against the brake member with a predetermined amount of wear. I have. Furthermore, when the wear detection sensor is connected to a wear detection sensor line that connects the wear detection sensor and the power supply, and the wear detection sensor comes into contact with a ground member and a current flows from the power supply to the ground through the wear detection sensor line, the current is detected. A wear detection switch circuit which is turned on by the switch and thereafter keeps the ON operation state continuously, and a wear detection switch which is branched from the wear detection sensor and is always connected to the ground side and has a predetermined electric resistance. An abnormality detection line that supplies an abnormality detection current smaller than the current value for turning on the circuit, and an abnormality detection switch circuit that detects the presence or absence of the abnormality detection current flowing through the abnormality detection line and is turned on when the abnormality detection current is lost. A wear alarm means for performing an alarm operation when the wear detection switch circuit is turned on, and an abnormality detection switch circuit. Having an abnormality warning means for performing warning operation when it is down operation, and an abnormality alarm activation blocking circuit abnormality detection switch is prevented from being turned on activated when worn detection switch circuit is turned actuated.

Further, an operation check switch which can be turned on from the outside, and an operation for temporarily performing an alarm operation by the wear alarm means and an alarm operation by the abnormality alarm means when the operation check switch is turned on. Preferably, an inspection circuit is provided.

[0009]

When the wear detecting device having the above structure is used, when the brake lining of the lining member is worn to the wear limit (a predetermined amount or more), the wear detection sensor comes into contact with the member connected to the ground side. As a result, a current flows from the power supply via the wear detection sensor, and the wear detection switch circuit is turned on by the current, and an alarm operation is performed by the wear alarm means. Once the wear detection switch circuit is once turned on, the on state is maintained thereafter, and the alarm operation by the wear alarm means is continued. Also,
When a disconnection or a contact failure occurs in the line from the power supply to the wear detection sensor, the abnormality detection switch circuit is turned on in response to the interruption of the current due to the disconnection or the contact failure, and the alarm is activated by the abnormality alarm unit. . As described above, the wear of the brake lining is separately alarmed by the wear alarm means, and the disconnection of the wiring and the contact failure are individually alarmed by the abnormality alarm means. However, when the wear detection switch circuit is turned on, the abnormal alarm operation is prevented. The means prevents the abnormality detection switch from being turned on, so that the wear alarm operation and the abnormality alarm operation are performed simultaneously, and there is no confusion. Here, when the alarm operation is not performed, by turning on the operation check switch, the temporary alarm operation by the wear alarm means and the abnormality alarm means is performed, and whether or not both the alarm means operate normally. Can be checked in advance.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. The electric circuit constituting the brake lining wear detecting device according to the present invention is configured as shown in FIG. This circuit includes a wear detection sensor 10, a wear detection switch circuit 20, an abnormality detection switch circuit 28, a wear alarm lamp 41, an abnormality alarm lamp 42, and first to sixth resistors R1 to R8.
R6 and the like are arranged as shown in the figure.

The wear detecting sensor 10 is attached to the brake shoe 1, as shown in FIG. The brake shoe 1 is a member corresponding to a lining member in the claims, and includes a support plate 2 made of a steel plate and a lining 3 provided on the support plate 2, and penetrates the support plate 2 and the lining 3. Sensor mounting hole 4
Are formed. A mounting screw is formed in a portion of the support plate 2 in the sensor mounting hole 4, and the wear detection sensor 10 is inserted into the sensor mounting hole 4,
The screw portion 11 a is screwed and attached to a mounting screw of the support plate 2.

As shown in FIG. 3, the wear detecting sensor 10 includes a body 11 having a hexagonal head 11c at one end and an insertion hole 11b extending in the axial direction, and a copper or the like inserted into the insertion hole 11b. Contact rod 12 made of a conductive material such as
A pair of rubber holding members 13 disposed in the insertion hole 11b so as to sandwich the central flange portion 12b of the contact rod 12 from both sides, and a washer 14 attached to cover the opening of the insertion hole 11b. And a snap ring 15 for fixing the washer 14. The tip 12a of the contact rod 12 protrudes forward from the other end of the body 11. A rear end 12c of the contact rod 12 protrudes rearward from one end of the body 11, and a screw is formed in this protruding portion. The contact rod 12 is used to hold the holding member 1.
3 is insulated from the body 11. The contact rod 1 projecting rearward in a state where the wear detection sensor 10 having the above configuration is mounted in the sensor mounting hole 4 as shown in FIG.
The sensor line 51c and the ground line 55 are connected to the rear end 12c of the second member 12 by a nut 16 screwed thereto. These two lines will be described later.

The brake shoe 1 to which the wear detection sensor 10 is attached is disposed so as to face a brake drum 5 (which corresponds to a brake member in the claims), and the lining 3 of the brake shoe 1 is braked. By pressing against the inner surface of the drum 5, the rotation of the brake drum 5 is braked by the frictional force between them. When this brake operation is repeated, the lining 3 gradually wears out,
When the amount of wear exceeds a predetermined amount, the tip 12a of the contact rod 12 protruding into the sensor mounting hole 4 comes into contact with the brake drum 5. For this reason, the contact rod 12 which has been insulated by the holding member 13 is
Is connected to the ground side via

When the contact rod 12 is connected to the ground side in this way, the sensor line 51c and the ground line 55 connected to the contact rod 12 are also grounded, and accordingly, the wear in the electric circuit shown in FIG. The alarm lamp 41 is turned on, which will be described.

The wear detecting sensor 10 includes the lines 51a, 5
1b, 51c (this is referred to as a sensor line 51) and connected to the battery 8, and the sensor line 51 is connected to the wear detection switch circuit 2 via a line 52a.
0 is connected. The wear detection switch circuit 20 includes first to third transistors 21 to 2 connected as illustrated.
3 and a relay switch 25 including a relay solenoid 25a and a switch body 25b. The wear of the lining 3 of the brake shoe 1 is small, and the wear detection sensor 10
When the tip 12a of the contact rod 12 is not in contact with the brake drum 5, the current flowing through the line 51c is extremely small, and the current flows from the line 52a to the base side, so that the first transistor 21 is turned on and the line 52b
, A current flows to the line 52c. The wear detection sensor 10 is connected to a grounded line 55 having the third photodiode 33a, but the current flowing through this line 55 is extremely small due to the internal resistance of the third photodiode 33a.

As described above, when the first transistor 21 is on, a current flows from the line 52b to the line 52c,
Since no current flows through the line 53a, the second transistor 22 is turned off, and no current flows through the lines 53b and 53c. Further, since no current flows through the line 54a, the third transistor 23 is also turned off, and the line 5a
No current flows through 4b and 54c. Here, the relay solenoid 25a is disposed on the line 54b. The relay solenoid 25a is not excited, the switch 25b is turned off, and the relay switch 25 is turned off. Switch body 25 of this relay switch 25
No current flows through the lines 50a and 50b having the b, and the wear warning lamp 41 disposed in the line 50a is turned off. As described above, when the wear of the lining 3 of the brake shoe 1 is small and the contact rod 12a of the wear detection sensor 10 is not in contact with the brake drum 5, the wear alarm lamp 41 is off.

Next, when the lining 3 of the brake shoe 1 is worn and the contact rod 12a of the wear detecting sensor 10 comes into contact with the brake drum 5, that is, when the lining 3
Is considered to have worn to the wear limit. In this case, the contact rod 12 of the wear detection sensor 10 contacts the brake drum 5, and the contact rod 12 and the line 51c connected to the contact rod 12 are connected to the ground via the brake drum 5. Therefore, the current from the line 51b flows toward the line 51c, the current does not flow through the line 52a connected to the base of the first transistor 21, and the first transistor 21 is turned off. As a result, current flows from the line 52b to the bases of the second and third transistors 22 and 23 via the lines 53a and 54a, respectively, and both transistors 22 and 23 are turned on.

Once the second transistor 22 is turned on, a current flows through the lines 53b and 53c and no current flows through the line 51b.
Even if the contact rod 12 is separated from the brake drum 5, the first transistor 21 is kept off. That is, when the lining 3 is almost worn down to the wear limit, the contact rod 12 of the wear detection sensor 10 often comes in contact with or separates from the brake drum 5. When the first transistor 21 is turned off, the first transistor 21 is turned off thereafter, and the second and third transistors 22 and 23 are turned off.
Are kept in the on state. On the other hand, when the third transistor 23 is turned on, a current flows through the line 54b having the relay solenoid 25a, and the relay solenoid 25a is excited to turn on the switch body 25b. Lights up. This lighting allows the driver to know the lining wear. In this embodiment, the alarm lamp 41 is used as the alarm means, but an alarm buzzer may be used instead or together with the alarm lamp.

As described above, the circuit for detecting the wear of the lining and issuing an alarm by turning on the wear alarm lamp 41 has been described. The circuit shown in FIG. 1 includes a circuit for detecting an abnormality in the wiring of the alarm circuit. Is also provided, and this will be described. This is for detecting an abnormality (for example, disconnection) of the wear detection sensor 10 and the sensor line 51 connected thereto. Therefore, a line 55 is provided from the wear detection sensor 10 to the ground side.
5 is provided with a third photodiode 33a.

The third photodiode 33a constitutes a photocoupler in combination with the third phototransistor 33b. When there is no abnormality in the wear detection sensor 10 and the sensor line 51, a current flows through the line 55,
The third photodiode 33a emits light to turn on the third phototransistor 33b. The third phototransistor 33b is included in the abnormality detection switch circuit 28, and when the third phototransistor 33b is turned on, the line 5
A current flows from 5a to the line 55c, and no current flows to the line 55b. Since the line 55b is connected to the base of the fourth transistor 24, the fourth transistor 24 is also turned off in this case. Lines 56a and 56b are connected to both sides of the fourth transistor 24, and an abnormality alarm lamp 42 is provided on the line 56a. If the fourth transistor 24 is off, no current flows through these lines 56a and 56b, and the abnormality alarm lamp 42 is off.

Here, it is assumed that an abnormality occurs in the wear detection sensor 10 or the sensor line 51 and the current flowing to the line 55 is interrupted. In this case, the third photodiode 33a is turned off, and the third phototransistor 33b is also turned off. Therefore, current flows from the line 55a to the base of the fourth transistor 24 via the line 55b, and the fourth transistor 24 is turned on. As a result, current flows through the lines 56a and 56b, and the abnormality alarm lamp 42 is turned on to warn of the occurrence of the abnormality. In this case, a buzzer may be used instead of the lamp 42. As described above, in the circuit of FIG. 1, the wear of the lining 3 and the abnormality of the wear detection circuit and the like are separately detected, and the wear alarm lamp 41 and the abnormality alarm lamp 42 are separately displayed by lighting. Has become.

In this circuit, the line 50a
The fourth photodiode 34a is provided therein. The fourth photodiode 34a constitutes a photocoupler in combination with the fourth phototransistor 34b provided in the abnormality detection switch circuit 28. When the wear detection sensor 10 comes into contact with the brake drum 5 and the relay switch 25 is turned on, the fourth photodiode 34a
Is also turned on, and the fourth phototransistor 34b receiving the light emission from this is turned on. When the fourth phototransistor 34b is turned on, the fourth transistor 24 is turned off, and the abnormality alarm lamp 42 is turned off. That is, in this circuit, when the wear of the lining 3 is detected and the wear alarm lamp 41 is turned on, the abnormality alarm lamp 42 is not turned on by the fourth photodiode 34a and the fourth phototransistor 34b.

The circuit further includes an operation check switch 43.
Is provided. The switch 43 is a switch that turns on the first and second photodiodes 31a and 32a by energizing them. The first and second photodiodes 31a and 32a constitute a photocoupler in combination with the first and second phototransistors 31b and 32b, respectively. First phototransistor 31b
Is disposed in parallel with the switch body 25b of the relay switch 25, and the second phototransistor 32b is connected to the line 5
It is disposed on a line 56c branching from 6a and connecting to the ground. Therefore, when the operation check switch 43 is turned on, the first and second phototransistors 31b,
Both 32b are turned on, the wear alarm lamp 41 and the abnormality alarm lamp 42 are turned on, and the alarm lamps can be inspected.

[0024]

[Effects of the Invention] As described above, according to the present invention,
When the brake lining of the lining member wears to the wear limit (a predetermined amount or more), the wear detection sensor comes into contact with the member connected to the ground side, and a current flows from the power supply through the wear detection sensor, and the current is used to cause the wear detection switch When the circuit is turned on and an alarm operation is performed by the wear alarm means, once the wear detection switch circuit is once turned on, the on state is maintained continuously thereafter, and the alarm operation by the wear alarm means is continued. Therefore, it is possible to reliably notify that the lining has been worn. Also, when a disconnection or contact failure occurs in the line from the power supply to the wear detection sensor, the abnormality detection switch circuit is turned on in response to the interruption of the current due to the disconnection or contact failure, and the alarm operation by the abnormality alarm means is activated. The wear of the brake lining is separately alarmed by the wear alarm means, and the disconnection of the wiring, the contact failure, etc. are separately alarmed by the abnormality alarm means, so that it is possible to clearly indicate which failure is occurring. . Further, when the wear detection switch circuit is turned on, the abnormality detection switch is prevented from being turned on by the abnormality alarm operation prevention means, so that the wear alarm operation and the abnormality alarm operation are performed simultaneously. , Which can prevent confusion.

If an operation check switch is provided, turning on the operation check switch when the alarm operation is not performed causes a temporary alarm operation by the wear alarm means and the abnormality alarm means to perform both alarms. It can be checked in advance whether the means operates normally.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing a configuration of a brake lining wear detection device according to the present invention.

FIG. 2 is a cross-sectional view showing a mounted state of a wear detection sensor used in the device.

FIG. 3 is a cross-sectional view showing the wear detection sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake shoe 3 Brake lining 5 Brake drum 10 Wear detection sensor 12 Contact rod 21-24 Transistor 31a-34a Photodiode 31b-34b Phototransistor 41 Wear alarm lamp 42 Abnormal alarm lamp

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-50-29975 (JP, A) JP-A-55-33938 (JP, A) JP-A-52-151473 (JP, A) 141963 (JP, A) JP-A-50-10995 (JP, A) JP-A-55-129631 (JP, A) JP-A 63-22443 (JP, U) JP-A 61-44043 (JP, U)

Claims (2)

(57) [Scope of request for utility model registration] 1. A device for detecting wear of a brake lining in a friction brake including a lining member provided with a brake lining and a brake member against which the brake lining is pressed when a brake is actuated. A wear detection sensor that is attached to one of the brake members and that contacts the conductive ground member connected to the ground when the brake lining is pressed against the brake member in a state where the brake lining has worn by a predetermined amount or more; A wear detection sensor line connecting the detection sensor and the power supply; and a wear detection sensor connected to the wear detection sensor line, wherein the wear detection sensor comes into contact with the ground member and the current flows from the power supply to the ground side via the wear detection sensor line. When this flows, this current A wear detection switch circuit that is turned on by the switch and continuously maintains the on operation state, and that has a predetermined electrical resistance that is branched from the wear detection sensor and that is always connected to the ground side, An abnormality detection line for supplying an abnormality detection current smaller than the current value for turning on the detection switch circuit; and detecting the presence or absence of the abnormality detection current flowing through the abnormality detection line, and turning on when the abnormality detection current disappears. An abnormality detection switch circuit; wear alarm means for performing an alarm operation when the wear detection switch circuit is turned on; abnormality alarm means for performing an alarm operation when the abnormality detection switch circuit is turned on; An abnormality alarm function for preventing the abnormality detection switch from being turned on when the detection switch circuit is turned on. Wear detection device of the brake lining, characterized in that it consists of a blocking circuit. 2. An operation check switch which can be turned on from the outside, and when the operation check switch is turned on, an alarm operation by the wear alarm means and an alarm operation by the abnormality alarm means are temporarily performed. The wear detecting device for a brake lining according to claim 1, further comprising an operation check circuit for operating the brake lining.