JPH0986401A - Brake clearance detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate a brake clearance inspection by detecting the period of a time required from the time of setting the first set pressure value to the time of arrival of the second set pressure value and comparing this detection time with a set time to judge the state of a brake system when the brake pressure is controlled. SOLUTION: A pressure sensor 60 for measuring a brake pressure is placed in connection between a control valve 10 and a brake mechanism 50, and its output signal is fed in a control part 40. And when a vehicle stops and a stroke sensor 34 detects no operations of a brake, an inlet valve 15 is opened after a back-up valve 13 is closed and the memory time of the control part 40 is set to zero. And also, depending upon the detection signal of the pressure sensor 60, it is judged whether the pressure(s) in respective brake chambers 51, 52 are set to the set pressure(s) or not. Furthermore, as well as the back-up valve 13 is opened, the inlet valve 15 is closed and when the memory time is judged to be more than its set value, a warning device is operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake clearance detecting device for detecting an abnormality in a brake system.

[0002]

2. Description of the Related Art As a vehicle brake, for example, in the case of a drum brake, brake braking is performed by crimping a brake shoe having a brake lining stretched on a friction surface to the drum. When the brake lining wears for a predetermined amount or more, the responsiveness of brake operation deteriorates and the braking force decreases, and further wear causes damage to parts such as brake shoes. The worn state of the brake lining can be recognized by the state of the clearance (shoe clearance) between the brake lining and the brake drum.

The shoe clearance (brake clearance) can be checked by directly measuring the push rod stroke of the brake chamber or the clearance between the drum and the lining.

As a device for detecting the brake clearance, a detection rod is slidably provided on the inner surface of the casing at the end of the stroke of the air piston.
There is a structure in which a switch provided separately is activated by the movement of the detection rod (Japanese Patent Publication No. 3-105).
No. 42). The switch is set to operate in response to a piston stroke when the clearance between the brake lining and the brake drum becomes a predetermined value or more due to wear of the brake lining.

[0005]

However, in order to directly measure the push rod stroke of the brake chamber and the clearance between the brake drum and the boulek lining, it is necessary to disassemble a part of the brake mechanism, and the measurement work is required. The inspection is very difficult because it is troublesome.

Further, in the device provided with the above-mentioned brake clearance detecting device, a large number of parts are required for the switch and its operating mechanism, so that the assembly becomes complicated. Further, since the switch is externally attached to the casing, the device becomes large and the weight also increases. Further, since a complicated mold and perforation for providing the switch and the rod on the casing are required, there is a problem that the processing cost increases as well as the component cost. Further, when detecting the brake clearance, only an abnormal value can be detected.

The present invention has been made in view of the above matters, and it is a technical object of the present invention to provide a brake clearance detection device capable of easily inspecting the brake clearance.

Further, it is a technical object to provide a brake clearance detecting device having a simple structure and a low cost.

[0009]

In order to solve the above technical problems, the present invention has the following constitution. That is, in the configuration of claim 1, the pressure source 30 and the brake mechanism 5 connected to the pressure source 30 via the control valve 10.
0, a pressure sensor 60 connected between the control valve 10 and the brake mechanism 50 to measure the brake pressure, and a control unit 40 connected to the control valve 10 and the pressure sensor 60. Detects the time required for the brake pressure to reach the second set pressure value from the first set pressure value based on the signal from the pressure sensor 60 when the control valve 10 controls the brake pressure. The brake clearance detecting device is configured to judge the state of the brake system by comparing the required time with the set time.

In the configuration of claim 2, the control unit 4
With 0, the brake pressure when the brake is not operated is set as the first set pressure value, and the time required for the brake pressure to be increased from the first set pressure value to the second set pressure value is detected.

In the configuration of claim 3, the control section 4
With 0, the brake pressure when the brake is not operated is set to the second set pressure value, and the time required for reducing the brake pressure from the first set pressure value to the second set pressure value is detected.

It is also possible to provide an alarm device for issuing an alarm to the driver with a voice or a lamp, and to activate this alarm device when the control unit 40 detects an abnormality in the brake clearance. .

The pressure source 30 can be exemplified by an air tank that supplies compressed air in the direction of the brake mechanism.
The brake mechanism 50 can be exemplified by a drum brake or a disc brake, and includes a brake chamber to which a brake pressure is supplied. The brake mechanism 50 can be configured to operate by air supplied from the pressure source 30 to the brake chamber (full air brake system). In addition, the brake mechanism 50
Can be configured so that the air pressure from the pressure source 30 is converted into a hydraulic pressure via an air booster and is activated by the hydraulic pressure supplied to the brake chamber (air over hydraulic system).

The control unit 40 includes a central processing unit (CP).
U), a read / write memory (RAM), a read-only memory (ROM), an input / output device (I / O), and a bus connecting these may be configured. The controller 40 is provided with a timer mechanism.

The pressure sensor 60 is connected between the brake mechanism 50 and the control valve 10 and measures the brake pressure. It is desirable to connect the pressure sensor 60 as much as possible downstream, that is, in the vicinity of the brake chamber in the case of a full air brake system. Further, in the case of an air over hydraulic system, it is desirable to connect it near the air booster. In addition,
The control valve 10 and the pressure sensor 60 may be integrally formed.

The pressure sensor 60 may be of any type as long as it can detect the brake pressure. For example, a Si diaphragm type pressure sensor can be exemplified.

Further, the present apparatus can be completed without adding new components by utilizing the components of the existing electric control brake (EBS).

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. The present device includes a pressure source 30 that generates compressed air, and a first conduit A that connects the pressure source 30 and the brake chambers 51 and 52 of the brake mechanism 50. A relay valve 11 (control valve 10) is inserted in the middle of the first conduit A. The relay valve 11 sends an air pressure corresponding to the signal pressure input to the relay valve 11 to the brake chambers 51 and 52. The brake chamber 51 is a brake chamber on the right side of the rear wheel, and the brake chamber 52
Is the brake chamber on the left side of the rear wheel.

The relay valve 11 is also connected to the discharge port 58 by the second conduit B. Then, the first pipeline A in the preceding stage (pressure source 30 side) of the relay valve 11
And the second conduit B are connected by a third conduit C. An inlet valve 15, which is a normally closed solenoid valve, and an outlet valve 17, which is also a normally closed solenoid valve, are inserted in the middle of the third conduit C. The inlet valve 15 is arranged upstream of the outlet valve 17 (on the pressure source 30 side). The third conduit C between the inlet valve 15 and the outlet valve 17 and the relay valve 11 are connected by a fourth conduit D.

The pressure source 30 and the fourth conduit D are connected by a fifth conduit E. A brake valve 31 that is operated by operating the brake pedal 32 and a backup valve 13 that is a normally open electromagnetic valve are inserted in the middle of the fifth conduit E. Brake valve 3
No. 1 is arranged at a stage before the backup valve 13 (on the pressure source 30 side).

A pressure sensor 60 is connected to the first conduit A between the relay valve 11 and the brake chambers 51 and 52. Further, a stroke sensor 34 for detecting the operation state of the brake pedal 32 is provided near the brake pedal 32.

The backup valve 13, inlet valve 15, outlet valve 17, pressure sensor 60, and stroke sensor 34 are electrically connected to the control unit 40. The control unit 40 is composed of a microcomputer (ECU), and has a central processing unit (CPU), a read / write memory (RAM), a read only memory (ROM), and an input / output device (I / O).
And a bus connecting these. Further, the control unit 40 is provided with a timer mechanism.

Next, the operation of the present apparatus will be described. During normal braking by electric control, the stroke of the brake pedal 32 is detected by the stroke sensor 34, and the detected value is output to the control unit 40. Based on the information from the stroke sensor 34, the control unit 40 outputs a signal to the backup valve 13, the inlet valve 15, and the outlet valve 17 so that the pressure corresponding to the pedal stroke is supplied to the brake chambers 51 and 52. To do. At this time, the open backup valve 13 is closed (ON), and the air signal pressure from the brake valve 31 is shut off. And the inlet valve 1 which was blocked
5 is opened (ON), and the signal pressure from the pressure source 30 is the first
The relay valve 11 is reached via the conduit A, the third conduit C, the inlet valve 15 and the fourth conduit D. Relay valve 1
1 supplies air corresponding to the signal pressure from the pressure source 30 to the brake chambers 51 and 52 through the first conduit A. The brake pressure in the brake chambers 51 and 52 is measured by the pressure sensor 6
It is fed back to the control unit 40 by sensing 0, and when the command pressure is reached, the inlet valve 15 is closed (O
FF) to hold the brake pressure.

When the stroke sensor 34 detects that the brake pedal 32 has been returned, the controller 40 opens the outlet valve 17 while keeping the backup valve 13 and the inlet valve 15 closed during the pressure reduction of the normal brake by electric control. (ON) and relay valve 1
The signal pressure of 1 is discharged through the path of the fourth conduit D → the third conduit C → the outlet valve 17 → the third conduit C → the second conduit B → the discharge port 58. The air in the brake chambers 51 and 52 is
Since the relay valve 11 is in the non-operating state, it is discharged to the atmosphere through the first conduit A → the relay valve 11 → the second conduit B → the discharge port 58.

Further, when the braking by electric control cannot be performed due to an electric failure or the like, each valve is in an inoperative state, that is, the backup valve 13 is open, the inlet valve 15 is closed, and the outlet valve 17 is also closed. Becomes Here, the air from the brake valve 31 is directly input as a signal pressure to the relay valve 11 via the fifth conduit E → the backup valve 13 → the fifth conduit E → the fourth conduit D. Then, the air from the pressure source 30 is supplied to the brake chambers 51 and 52 via the relay valve 11. When reducing the brake pressure, the brake valve 3
As the signal pressure is exhausted from the exhaust port provided in No. 1, the air in the brake chambers 51 and 52 is exhausted from the exhaust port 58.
Emitted from.

Next, the operation of detecting the brake clearance will be described. First, the relationship between the pressurizing time (depressurizing time) of the brake pressure and the brake clearance will be described with reference to FIG. Brake chamber 5 with brake inactive
The brake pressure in 1, 52 is the base point O (first set pressure value)
When the time required to start the pressurization of the brake pressure from the base point O to reach the set value P (second set pressure value) is smaller than the set time T2a (for example, T1a)
Means that the brake clearance keeps a regular clearance and the brake lining is normal.
Further, when the required time is equal to or longer than the set time T2 (for example, T3a), it means that the brake clearance is excessively large and the brake lining is excessively worn (left side in FIG. 2).

The above is the mode in which the brake clearance is detected based on the pressurization time of the brake pressure, but the brake clearance can be detected based on the depressurization time of the brake pressure. That is, when the brake pressure in the brake chambers 51 and 52 reaches the set value P (first set pressure value), the brake pressure starts to be reduced, and the brake pressure is set to the base point O (second set pressure value). This is a mode in which the time required until the above is measured (right side in FIG. 2). Also in this aspect, when the required time is less than the set time T2b (for example, T1
In b), the brake clearance is a regular clearance, and when the required time is the set time T2b or more (for example, T
3b) means that the brake clearance is excessive.

Next, the flow chart of the control section 40 shown in FIG. 3 will be mainly described. In step 101, it is determined whether or not the vehicle has stopped based on information from a speed sensor (not shown). The affirmative branch of step 101 proceeds to step 102, where it is determined from the information from the stroke sensor 34 whether or not the brake is operating.
The negative branch of the step 101 and the negative branch of the step 102 (when the brake is operated) becomes the circulation routine of the step 101.

Then, in step 103, the backup valve 13 is closed (ON). Step 104
In, after the time T stored in the control unit 40 is set to 0, the inlet valve 15 is opened (ON). In step 106, it is determined from the information from the pressure sensor 60 whether the pressure in the brake chambers 51 and 52 has reached a preset set value P. The negative branch of step 106 shifts to step 107 to determine whether 1 millisecond has elapsed. The negative branch of step 107 is step 107
Then, the affirmative branch of step 107 shifts to step 108 and 1 is set at the time T currently stored.
After the time obtained by adding milliseconds (T + 1) is newly stored as time T, the circulation routine of step 105 is started.

The affirmative branch of step 106 is step 1
In step 09, the backup valve 13 is opened, the inlet valve 15 is closed, and step 110 is executed. In step 110, it is determined whether the time T stored in the control unit 40 is equal to or greater than a preset set value. In the affirmative branch of step 110, an alarm device (not shown) is activated to let the driver recognize that the wear of the brake lining is accelerated. Also, step 1
In the negative branch of 10, the alarm is not activated because the brake clearance is normal.

As described above, according to the present embodiment, the existing components of the electric control brake are used as the brake clearance detecting device, so that it is not necessary to separately provide a new component, and the accuracy can be reduced at a low cost. It is possible to obtain a good brake clearance detection device.

In the present embodiment, this device is used as a brake clearance detecting device, but this device can also be used as a device for detecting an abnormality in the brake system such as a liquid leak.

Further, the detection of the brake clearance by this device may be automatically performed, for example, every time the engine is operated, or may be performed by a switch operation of the driver.

[0034]

According to the present invention, it is possible to provide a brake clearance detecting device which can easily inspect the brake clearance.

Further, it is possible to provide a low cost brake clearance detection device having a simple structure.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a pressurization time (decompression time) of a brake pressure and a brake clearance in the embodiment of the present invention.

FIG. 3 is a flowchart of a control unit according to the embodiment of the present invention.

[Explanation of symbols]

 10 ・ ・ Control valve 11 ・ ・ Relay valve (control valve) 13 ・ ・ Backup valve 15 ・ ・ Inlet valve 17 ・ ・ Outlet valve 30 ・ ・ Pressure source 31 ・ ・ Brake valve 32 ・ ・ Brake pedal 34 ・ ・ Stroke sensor 40 .. Control unit 50 .. Brake mechanism 51, 52 .. Brake chamber 58 .. Outlet 60 .. Pressure sensor A .. First pipe line B .. Second pipe line C .. Third pipe line D .. 4th pipeline E ... 5th pipeline

Claims (3)

[Claims] 1. A pressure source, a brake mechanism connected to the pressure source via a control valve, a pressure sensor connected between the control valve and the brake mechanism to measure a brake pressure, the control valve, and A control unit connected to the pressure sensor, wherein the control unit controls the brake pressure from the first set pressure value to the second set pressure value based on a signal from the pressure sensor when the control valve controls the brake pressure. A brake clearance detection device characterized by detecting a required time until reaching a set pressure value and comparing the required time with a set time to judge a state of a brake system. 2. The required time for the control unit to increase the brake pressure from the first set pressure value to the second set pressure value by setting the brake pressure when the brake is not operated as the first set pressure value. The brake clearance detecting device according to claim 1, wherein 3. The controller sets a brake pressure when the brake is not operated as a second set pressure value, and sets a time required for reducing the brake pressure from the first set pressure value to the second set pressure value. The brake clearance detection device according to claim 1, wherein the brake clearance detection device detects the brake clearance.