JP2772737B2 - Brake switch failure detection device - 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 switch failure detecting device for detecting an operation state of a brake pedal for a vehicle such as an automobile.

[0002]

2. Description of the Related Art Conventionally, there has been known a system in which a signal from a brake switch which is turned on by depressing a brake pedal is input to an electronic control circuit for engine control to control the engine in accordance with the operation state of the brake pedal. (See JP-A-61-271131). However, conventionally, means for detecting a failure of the brake switch has not been provided, and a signal different from the actual operation state of the brake pedal is input from the brake switch to the control circuit, and the engine is operated according to the operation state of the brake pedal. Could not be controlled properly.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an apparatus which can detect when a brake switch has failed.

[0004]

In order to achieve the above object,
The present invention is an apparatus for detecting a failure of the probe <br/> rake switch that in depression of the brake pedal, brake
Means for detecting the booster pressure, which is the internal pressure of the
Means for detecting the pedaling force applied to the rake pedal;
For detecting the brake pressure of the hydraulic circuit
And the degree of change in booster pressure, pedaling force and brake pressure.
Brake operation status and brake switch
And an on / off state of the brake switch to determine whether a brake switch has failed.

[0005]

[Function] In addition to the degree of change in booster pressure and the brake pedal
The brake is activated based on the applied pedaling force and brake pressure.
To determine if the brakes have been applied.
When it is determined that the brake switch is off, or when it is determined that the brake is released and the brake switch is on, it is determined that the brake switch is faulty. Here, the degree of change of the booster pressure and the brake pedal
Both the pedaling force and the brake pressure applied to the brake
Is a parameter directly related to the dynamic state,
Of the detecting means, the pedal force detecting means, and the brake pressure detecting means.
Even if one of them fails, the signal from the remaining detection
Brake switch and determine whether the brake switch
Switch can accurately determine the presence or absence of a
Increase.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, 1 is a brake pedal, 2 is a brake booster connected to an intake pipe of an engine via a negative pressure pipe 3, and 4 is a master cylinder, when the brake pedal 1 is depressed. The piston in the master cylinder 4 is operated by the boosting action using the negative pressure of the intake air of the engine by the brake booster 2, and pressurized oil is supplied from the master cylinder 4 to the cylinder of the brake 6 via the hydraulic pipe 5, Was made to actuate braking.

A brake switch 7 which is turned on when the brake pedal 1 is depressed is provided, and a signal from the switch 7 is sent to an electronic control circuit for engine control (hereinafter referred to as ECU).
The cruise control is released when the brake pedal 1 is depressed during the cruise control, for example.

Further, a pedaling force sensor 9 comprising a load cell for detecting a stepping force, that is, a stepping force T of the brake pedal 1,
A booster pressure sensor 10 connected to the negative pressure pipe 3 for detecting the internal pressure PB (hereinafter, referred to as booster pressure) of the brake booster 2, and a brake pressure sensor for detecting the output oil pressure PO (hereinafter, referred to as brake pressure) of the master cylinder 4. And signals from these sensors 9, 10, 11 are also provided by the ECU.
8 and the ECU 8 executes the failure detection program shown in FIG. 2 as a subroutine to determine whether the brake switch 7 has failed.

More specifically, in FIG. 2, S1 is a step for judging whether or not the degree of change ΔPB of the booster pressure PB is equal to or more than a predetermined value ΔPBs. S2 is a judgment for judging whether or not the brake pressure PO is equal to or more than a predetermined value POs. Step S3 is the pedaling force T
Is a step of determining whether or not is greater than or equal to a predetermined value Ts,
Each of the predetermined values ΔPBs, POs, and Ts is set to a value serving as a criterion for determining the operation of the brake. When the brake is depressed by depressing the brake pedal 1, ΔPBs, POs, and Ts
When at least one of the three conditions of B ≧ ΔPBs, PO ≧ POs, and T ≧ Ts is satisfied, and none of the three conditions is satisfied, the brake is released, that is, the brake pedal 1
It can be determined that has not been depressed.

Therefore, when one of the three conditions is satisfied, the routine proceeds to step S4 where the brake switch 7
It is determined whether or not the brake pedal is on.
It is determined that the brake switch 7 has been kept off due to an off fault such as a connecting line despite that the brake pedal has been depressed, and when a predetermined time has elapsed with the brake switch kept off, the process goes to step S6 through step S5. Proceed and perform an appropriate fail-safe process such as displaying the occurrence of an OFF failure.

If none of the three conditions is satisfied, the routine proceeds to step S7, where it is determined whether or not the brake switch 7 is turned on. It is determined that the switch 7 remains on due to an ON failure such as welding, and when a predetermined time has elapsed while the switch 7 remains on, the process goes to step S9 through step S8.
To perform the appropriate fail-safe processing such as displaying the occurrence of the ON failure.

In the above embodiment, the pedaling force sensor 9 and the booster pressure sensor 1 are used to detect the operating state of the brake 6.
Although three detecting means of 0 and the brake pressure sensor 11 are provided, it is a matter of course that the present invention is not limited to this.

[0013]

As is apparent from the above description, according to the present invention, the redundancy of brake switch failure determination is increased.
Thus, the reliability of the control related to the brake switch can be improved.

[Brief description of the drawings]

FIG. 1 is a system diagram of an example of the apparatus of the present invention.

FIG. 2 is a flowchart showing a failure detection program.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Brake pedal 7 Brake switch 8 ECU (discrimination means) 9 Treading force sensor (detection means) 10 Booster pressure sensor (detection means) 11 Brake pressure sensor (detection means)

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-4-123966 (JP, A) JP-A-53-146077 (JP, A) JP-A-60-234045 (JP, A) JP-A-61- 81834 (JP, A) Hikaru Hei 2-13874 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) B60T 17/18-17/22

Claims (1)

(57) [Claims] 1. Turn on by depressing a brake pedal
An apparatus for detecting a failure of a brake switch that, means for detecting the internal pressure serving booster pressure of the brake booster
When means for detecting a depression force applied to the brake pedal, detects the hydraulic pressure serving as a brake pressure of a hydraulic circuit of the brake
Based on the means, the degree of change of the booster pressure, the pedal effort, and the brake pressure.
Determined brake operation state and brake switch off
A brake switch failure determination unit that determines whether there is a failure in the brake switch by comparing the brake switch with an on / off state.