JPH0914314A - Electric type pad ware indicator - Google Patents

Abstract

PURPOSE: To simplify wiring so as to make its changing unnecessary by arranging a magneto-sensitive element between each magnetic material and each magnetic field generating source, connecting the magneto-sensitive element with each other in series and issuing an alarm based on the output signal of the magneto-sensitive element. CONSTITUTION: Friction pads 18 and 20 are composed of back metals 22 and 24 each made of a strong magnetic material and friction materials 26 and 28 provided in the front face opposite the rotor 16 of the back metals 22 and 24. Magneto-resistant elements 30 and 32 as magneto-sensitive elements are arranged between the N poles of a pair of permanent magnets 12 and 14 as magnetic field generating sources. Then, these magneto-resistant elements 30 and 32 are formed in one side AB of a bridge circuit 36 and an alarm lamp 44 lit depending on a change in the resistance values of the magneto-resistant elements 30 and 32 is provided in a bridge BD in the center of the bridge circuit 36. Thus, wiring is made simple and changing of the magneto-resistant elements 30 and 32 is made unnecessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric pad wear indicator for electrically detecting wear of a brake friction pad and issuing an alarm.

[0002]

2. Description of the Related Art A vehicle brake is used to decelerate or stop a running vehicle. Generally, a friction pad made of a friction material is pressed against a rotor or a drum rotating with a wheel to generate rotational kinetic energy. Is converted into thermal energy by friction to obtain a braking force. When the friction pad wears, the brake cannot operate normally because it becomes dangerous, and therefore the wear of the friction pad can be detected. An electric pad wear indicator that gives an alarm by a buzzer is widely adopted.

As a conventional pad wear indicator for electrically detecting the wear of the friction pad, a wire break type indicator is generally used. This wire breaker type pad wear indicator is made by attaching a conductive wire to the backing of the friction pad so that it protrudes toward the rotor surface.If the wire touches the rotor and cuts due to wear of the pad, an alarm lamp will light up or an alarm buzzer will sound. Is supposed to ring. Further, Japanese Patent Laid-Open No. 60-139930 discloses a pad wear indicator for detecting that a back metal of the pad approaches the rotor due to wear of the friction pad by using a proximity sensor.

[0004]

However, since the above-mentioned wire breakage type pad wear indicator is designed such that the conductive wire is attached to the friction pad, the workability at the time of replacement or the like is poor. Further, the disconnection-type padware indicator cannot be reused when the conductive wire is disconnected, and is expensive because it is disposable. on the other hand,
The pad wear indicator using the proximity sensor described in JP-A-60-139930 is not damaged because it does not come into contact with the rotor. However, in the one disclosed in Japanese Patent Laid-Open No. 60-139930, the sensor on the inner side and the sensor on the outer side are independent, so that the wiring is not only doubled and complicated, but also the work man-hours are increased. Will increase.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide an electric pad wear indicator which can simplify wiring and does not require replacement.

[0006]

In order to achieve the above object, a first electric pad wear indicator according to the present invention is an electric pad wear indicator which electrically detects wear of a friction pad for a brake and issues an alarm. In the pad wear indicator, magnetic field generation sources arranged on both sides of the rotor, magnetic bodies provided at positions corresponding to the magnetic field generation sources of the friction pads pressed by the rotor, these magnetic bodies and the magnetic field generation sources, respectively. A magnetic sensitive element which is arranged between the magnetic sensitive element and the magnetic sensitive element and which is connected in series with each other and outputs a signal according to the magnetic flux passing therethrough; Has become.

A second aspect of the present invention is an electric pad wear indicator that electrically detects wear of a brake friction pad and issues an alarm, and a magnetic field provided on each of the friction pads disposed on both sides of the rotor. A magnetic sensitive element which is arranged at a position corresponding to the magnetic field generating source on both sides of the rotor and the magnetic field generating source and which is connected in series with each other and outputs a signal according to a magnetic flux to be transmitted, and the magnetic sensitive element. And an alarm generation unit for issuing an alarm based on the output signal of the above.

Further, a third aspect of the present invention is an electric pad wear indicator for electrically detecting wear of a brake friction pad and issuing an alarm, the electric pad wear indicators being arranged on both sides of a rotor, connected in series with each other, and having a high frequency. A coil that generates a magnetic field, an electric conductor provided at a position corresponding to the coil of a friction pad that is in pressure contact with the rotor, and an alarm that issues an alarm based on a change in impedance of the coil due to an eddy current generated in the electric conductor It is configured to have a generator.

Further, a fourth aspect of the present invention is an electric pad wear indicator for electrically detecting wear of a brake friction pad to give an alarm, and a magnetic field generation source arranged in a radial direction of a rotor, and this magnetic field generation. A magnetic sensitive element that is arranged to face the source and outputs a signal according to the magnetic flux that is transmitted, a ferromagnetic body provided on a friction pad that is in pressure contact with the rotor, and at least opposite to the magnetic field generation source of the magnetic sensitive element. Based on an output signal of the magnetic sensitive element, which is provided on the side and has a length equal to or greater than the wall thickness dimension of the rotor to form a magnetic path with the ferromagnetic body of the friction pad and the magnetic field generation source. It is configured to have an alarm generation unit for issuing an alarm.

[0010]

The first to third aspects of the present invention configured as described above.
In the above, since the magnetic sensitive element or coil serving as the inner side detecting element and the magnetic sensitive element or coil serving as the outer side detecting element are connected in series, the inner side or the coil is not connected without double wiring. It is possible to detect that one or both of the outer side friction pads are worn, and it is possible to simplify the wiring. Moreover, the wear of the friction pad is detected by the change of the magnetic field (magnetic flux).
Since the wear of the pad can be detected in a non-contact manner, it is not necessary to replace the magnetic sensitive element or the coil, and the cost can be reduced. Further, in the fourth aspect of the present invention, the arms are projected to both sides of the rotor to form a magnetic path with the ferromagnetic material provided on the friction pad.
The wear of the outer side or inner side friction pad can be detected by one magnetic sensitive element, and the structure can be simplified and the cost can be reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of an electric pad wear indicator according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory view of an electric pad wear indicator according to a first embodiment of the present invention. The sensor 10 of the pad wear indicator is attached to a support fixed to a vehicle body (not shown) and has a pair of permanent magnets 12 and 14 which are magnetic field generation sources. These permanent magnets 12 and 14 are located on the outer side and the inner side, which are both sides of the rotor 16 that rotates with a wheel (not shown), and are arranged such that their magnetic pole surfaces are parallel to the rotor axis. One of the magnetic poles (the N pole in the embodiment) faces the side surfaces of the outer friction pad 18 and the inner friction pad 20.

Each of the friction pads 18, 20 is composed of a backing metal 22, 24 made of a ferromagnetic material, and friction materials 26, 28 provided on the front surface of the backing metal 22, 24 facing the rotor 16. And N of each permanent magnet 12, 14
Magnetoresistive elements 30 and 32, which are magnetically sensitive elements, are arranged between the poles and the friction pads 18 and 20. These magnetoresistive elements 30 and 32 are opposed to the north poles of the permanent magnets 12 and 14, and the friction materials 26 and 2 of the friction pads 18 and 20.
8 is worn away, the backing metal 22, 24 causes the rotor 16
The change in the magnetic flux (magnetic field) due to the approach to the variable resistor 34 is detected and is connected in series to the variable resistor 34 as shown in FIG.
One side AB is formed.

The bridge circuit 36 includes the other three sides BC,
The CD and DA have resistors 38, 40 and 42 respectively, and an alarm lamp (alarm generation unit) 44 which is turned on by a change in the resistance value of the magnetoresistive elements 30 and 32 is provided in the central bridge BD. It is provided via a switching element (not shown) such as a transistor. The alarm lamp 44 is installed in a console or the like in the vehicle compartment and lights up to notify the driver that the friction pad is worn. Further, a DC power supply 46 is connected between the connection point A and the connection point C. The variable resistor 34 is for adjusting the balance of the bridge circuit 36. In the initial state, that is, when the backing metals 22 and 24 of the friction pads 18 and 20 are shown by solid lines in FIG. When it is located away from 16, the resistance value is adjusted so that no current flows through the central bridge BD.

The operation of the first embodiment constructed as described above is as follows. The bridge circuit 36 is variable when the friction materials 26 and 28 of the friction pads 18 and 20 are not worn and the backing metals 22 and 24 are far from the rotor 16 as shown by the solid line in FIG. The resistor 34 is adjusted so that no current flows in the central bridge BD. Then, in a state where the backing metals 22 and 24 are located far from the rotor 16, the magnetic flux of each of the permanent magnets 12 and 14 of the sensor 10 exits from the N pole and enters the S pole.
Only a few pass through 0 and 32.

However, when the friction materials 26, 28 are worn and become thin and the backing plates 22, 24 approach the rotor 16 as shown by arrows 47, 48 in FIG. 1A, the backing plates 22, 24 become strong. Since it is made of a magnetic material, the permanent magnets 12, 1
The magnetic flux from the N pole of No. 4 passes through the backing metal 22, 24, and the magnetic flux passing through the magnetoresistive elements 30, 32 increases. Therefore, the resistance values of the magnetoresistive elements 30 and 32 gradually decrease, the voltage drop due to the magnetoresistive elements 30 and 32 changes, the balance of the bridge circuit 36 is lost, and a potential difference is generated across the central bridge BD. . And, for example, FIG.
As indicated by the broken line in (1), if any of the back metal 22 and 24 approaches the rotor 16 more than the specified value, the bridge circuit 3
The potential difference between the connection point B and the connection point D of 6 becomes the operating voltage of the switching element, the switching element is turned on, the alarm lamp 44 provided in the vehicle compartment is turned on, and the friction pad 1
It can be seen that 8 and 20 have worn.

As described above, in the embodiment, the rotor 1
6. Magnetoresistive element 3 arranged on the outer side and inner side of 6
By connecting 0 and 32 in series, it is not necessary to duplicate the wiring, the wiring can be simplified, and the number of work steps can be reduced. Moreover, in the embodiment,
The wear of the outer friction pad 18 and the inner friction pad 20 can be detected by one sensor. In the embodiment, the friction pads 18, 20 are contactless.
Since the wear of the sensor can be detected, even if the pad wears, the sensor 1
No damage is caused, no replacement is required, and the cost of the pad wear indicator can be reduced.

In the above embodiment, the case where the magnetic resistance elements 32 and 34 are used as the magnetic sensitive elements has been described, but a Hall element, a magnetic transistor or the like may be used. Further, in the above embodiment, the case where the two permanent magnets 12 and 14 are provided as the magnetic field generation source has been described, but a U-shaped magnet or a horseshoe-shaped magnet may be used. Further, in the above-described embodiment, the case where the permanent magnets 12 and 14 are used as the magnetic field generation source has been described, but a DC coil may be used as the magnetic field generation source. In the above-mentioned embodiment, the backing plates 22, 2 of the friction pads 18, 20 are
Although the case where 4 itself is formed of a ferromagnetic material has been described, the backing metal 22, 24 is formed of a non-ferromagnetic material such as an aluminum alloy, and the backing metal 22, 24 is made of a ferromagnetic material such as silicon steel or permalloy at a predetermined position. May be attached.

In the above embodiment, the case where the alarm lamp 44 is turned on has been described, but an alarm sound may be generated. In the above embodiment,
Although the case where the sensor 10 is provided with the permanent magnets 12 and 14 has been described, the permanent magnets may be attached to the backing plates 22 and 24 of the friction pads 18 and 20, respectively. In this case, the ferromagnetic material arranged on one side of the magnetoresistive elements 30 and 32 may be omitted. Further, in the above-described embodiment, the case where the sensor 10 is attached to the support has been described.
May be attached to a member that does not substantially move with respect to the rotor 16, such as a caliper of an opposed type disc brake.

FIG. 2 is an explanatory view of the second embodiment of the present invention. In FIG. 2, a pair of high frequency coils 52 and 54 are provided on the sensor 50 of the pad wear indicator. These coils 52, 54 are arranged on both sides of the rotor 16 and are mounted so that their axes are parallel to the rotor surface, that is, orthogonal to the rotor axis, and one of the coil holes is connected to the outer friction pad 18 and the inner friction pad. It faces the side surface of the friction pad 20. The backing plates 56, 58 of the friction pads 18, 20 are made of a conductor such as aluminum. Also, each high frequency coil 5
2 and 54 are connected in series and are also connected in series to the variable resistor 34 of the bridge circuit 36, and form one side AB of the bridge circuit 36. Further, the high frequency power source 6 is provided between the connection point A and the connection point C of the bridge circuit 36.
0 is connected so that a high-frequency magnetic field can be generated in the high-frequency coils 52 and 54 by the high-frequency power source 60.

In the second embodiment, an exciting current is supplied from the high frequency power supply 60 to the high frequency coils 52 and 54 of the sensor 50 to generate a magnetic field. And the friction pad 1
In the case of Nos. 8 and 20, the backing plates 56 and 58 made of a conductor are the friction material 2
When the rotors 6 and 28 approach the rotor 16 as indicated by arrows 47 and 48, eddy currents are generated in the backing metals 56 and 58 by the high frequency magnetic fields generated by the high frequency coils 52 and 54. Therefore, the high-frequency coils 52 and 54 are provided with the back metal 5
When the backing metal 56, 58 approaches the rotor 13 more than the specified value due to the impedance change under the influence of the eddy currents generated in the coils 6, 58, the parallel of the bridge circuit 36 is broken as in the above-mentioned embodiment and the central bridge BD. An electric current is applied to turn on the alarm lamp 44. As a result, the same effect as that of the above-described embodiment can be obtained.

FIG. 3 shows a third embodiment of the present invention. In FIG. 3A, the sensor 62 of the pad wear indicator has an H shape. This sensor 62
Has a permanent magnet 64 on the central abdomen (web) and a magnetoresistive element 66 attached to one pole (N pole in the embodiment) of the permanent magnet 64. And the sensor 62
Is disposed at a position lateral to the friction pads 18 and 20 (see FIG. 3B), and the permanent magnet 64 and the magnetoresistive element 66 are located at the center position in the thickness direction of the rotor 16 and the permanent magnet. The magnetic poles 64 are arranged so that the direction of the magnetic poles is the radial direction of the rotor 16.

Further, the sensor 62 includes a magnetoresistive element 66.
And a pair of sensor arms 68 and 70 made of a ferromagnetic material provided so as to sandwich the permanent magnet 64. These sensor arms 68 and 70 extend perpendicularly to the magnetic pole direction of the permanent magnet 64, that is, in the axial direction of the rotor 16, and both ends 68a, 68b, 70a, and 70b are arranged on the outer side of the rotor 16 and the inner side. Protruding to the side. further,
When the friction materials 26 and 28 are worn, the friction pads 18 and 20 have outer ends 6 of the sensor arms 68 and 70, respectively.
8a, 70a and inner side end portions 68b, 70b are provided with overlapping corner portions 72, 74 (see FIG. 3 (2)).
The corners 72, 74 are made of a ferromagnetic material and form a magnetic path together with the permanent magnet 64 and the pair of sensor arms 68, 70. The magnetoresistive element 66 forms one side of the bridge circuit 36 together with the variable resistor 34 shown in FIG.

In the third embodiment constructed as described above, the wear of the friction materials 26, 28 of the friction pads 18, 20 is small,
As shown by the solid line in FIG. 3A, when the backing metals 22 and 24 are located away from the rotor 16, the N of the permanent magnet 64 is reduced.
Most of the magnetic flux emitted from the pole directly enters the S pole, and the amount of magnetic flux passing through the magnetoresistive element 66 is small. Therefore, the alarm lamp 44 of the bridge circuit 36 does not light up. However, the friction materials 26 and 28 are worn away, the backing plates 22 and 24 approach the rotor 16 more than the specified value, and the corners 72 and 74 provided on the friction pads 18 and 20 become the ends 68a, 70a and 68 of the sensor 62.
b and 70b, most of the magnetic flux emitted from the N pole of the permanent magnet 64 passes through the magnetoresistive element 66,
The sensor arm 68, the corner 72 or the corner 74, the sensor arm 70, and the S pole of the permanent magnet 64 flow together with the magnetoresistive element 6.
The resistance value of 6 decreases and the parallelism of the bridge circuit 36 collapses,
The alarm lamp 44 is turned on and the wear of the friction pads 18 and 20 can be detected in the same manner as in the above embodiment. In the third embodiment, the case where the pair of sensor arms is provided has been described, but the sensor arm 70 may be omitted by providing only the sensor arm 68 on the magnetoresistive element 66 side.

[0025]

As described above, in the first to third aspects of the present invention, the magnetic sensitive element or coil serving as the inner side detecting element and the magnetic sensitive element or coil serving as the outer side detecting element. Since they are connected in series, it is possible to detect the wear of either the inner or outer friction pad without double wiring.
Wiring can be simplified. Moreover, the wear of the friction pad is detected by the change of the magnetic field, and the wear of the pad can be detected in a non-contact manner. Therefore, it is not necessary to replace the magnetically sensitive element or the coil, and the cost is reduced. be able to. Further, in the fourth aspect of the present invention, the arm is made to project to both sides of the rotor to form a magnetic path with the ferromagnetic material provided in the friction pad. The wear of the inner friction pad can be detected, and the structure can be simplified and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an electric pad wear indicator according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an electric pad wear indicator according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of an electric pad wear indicator according to a third embodiment of the present invention.

[Explanation of symbols]

 10 Sensor 12, 14 Magnetic Field Generation Source (Permanent Magnet) 16 Rotor 18 Outer Friction Pad 20 Inner Friction Pad 22, 24 Back Metal 26, 28 Friction Material 30, 32 Magnetic Sensitive Element (Magnetic Resistance Element) 44 Alarm Generation Section (Alarm Lamp) 50 sensor 52, 54 high frequency coil 56, 58 back metal 62 sensor 64 magnetic field generation source (permanent magnet) 66 magnetic sensitive element (magnetoresistive element) 68, 70 sensor arm

Claims (4)

[Claims] 1. An electric pad wear indicator for electrically detecting wear of a brake friction pad and issuing an alarm, wherein magnetic field sources disposed on both sides of a rotor and the magnetic field of the friction pad pressed by the rotor. A magnetic body provided at a position corresponding to the generation source, and a magnetic sensitive element which is arranged between each magnetic body and each magnetic field generation source and which is connected in series with each other and outputs a signal according to a magnetic flux to be transmitted. An electric pad wear indicator, comprising: an alarm generating section for issuing an alarm based on the output signal of the magnetically sensitive element. 2. An electric pad wear indicator for electrically detecting wear of a friction pad for a brake and issuing an alarm, wherein a magnetic field source provided on each of the friction pads arranged on both sides of the rotor and the rotor. On both sides,
A magnetic sensitive element which is arranged at a position corresponding to the magnetic field generation source and which is connected in series with each other and outputs a signal according to a magnetic flux to be transmitted, and an alarm generation unit which issues an alarm based on the output signal of the magnetic sensitive element. An electric pad wear indicator comprising: 3. An electric pad wear indicator for electrically detecting wear of a brake friction pad and issuing an alarm, wherein coils arranged on both sides of a rotor are connected in series and generate a high frequency magnetic field. It has a conductor provided at a position corresponding to the coil of the friction pad in pressure contact with the rotor, and an alarm generation unit for issuing an alarm based on a change in impedance of the coil due to an eddy current generated in the conductor. An electric pad wear indicator. 4. An electric pad wear indicator for electrically detecting wear of a brake friction pad and issuing an alarm, wherein a magnetic field source arranged in a radial direction of a rotor,
A magnetic sensitive element that is arranged to face the magnetic field generation source and outputs a signal according to the magnetic flux that is transmitted, a ferromagnetic material provided on a friction pad that is in pressure contact with the rotor, and at least the magnetic field generation of the magnetic sensitive element. An arm provided on the side opposite to the magnetic source, having a length equal to or greater than the thickness of the rotor and forming a magnetic path with the ferromagnetic body of the friction pad and the magnetic field generating source; and an output signal of the magnetic sensing element. An electric pad wear indicator, comprising: an alarm generating section for issuing an alarm based on the above.