JPH0241964A - Anti-lock brake control device having failure detecting means - Google Patents

Abstract

PURPOSE:To improve the safety of braking by deciding failure of a hydraulic control unit and giving a warning when differential pressure between a master cylinder and a wheel cylinder is more than a designated value and the differential pressure continues to be detected during the period of a designated time. CONSTITUTION:Regardless of anti-lock control or non-anti-lock control, a control unit 10 usually conducts ordinary braking for each wheel by wheel cylinders 4 through a master cylinder 2, each flow control valve 3 and a solenoid valve 5 by operating a brake pedal 1. Signals of differential pressure signals 7, 7' for detecting the differential pressure between a master cylinder 2 and a wheel cylinder 4 are input to the control unit, and when the differential pressure more than a designated value continues to be detected during the period of a designated time or more, the control unit decides failure of the flow control valve 3, the solenoid valve 5 or the like and gives a warning. For example, the anti-lock control is discontinued to perform safe braking. Thus, failure of a hydraulic control unit caused by mechanical factor can be surely detected so as to conduct braking operation more safely.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to failures in anti-lock brake systems for automobiles, particularly those in which the supply pressure to the wheel cylinders cannot be increased normally due to mechanical factors. The present invention relates to an anti-lock brake control device having failure mode detection means.

(Prior art) As a device for braking an automobile, the braking pressure caused by pressing the brake pedal is transmitted to the wheels through a hydraulic piping system to apply the brakes. Conventional anti-lock brake control devices are already known, in which when a knob occurs, a short-term opening dynamic pressure is relieved to avoid locking, and then braking pressure is applied again to repeat brake braking. The device is a two-channel system that controls the front two wheels independently and controls the rear two wheels to a predetermined hydraulic pressure by controlling the front two wheels, and the two front wheels independently controls the rear two wheels. Various systems have been proposed, including a 3-channel system that controls the wheels using a common independent control pressure, and a 4-channel system that controls each of the four wheels independently. The constituent control device calculates the wheel speed, estimated vehicle speed, wheel deceleration, slip amount, etc. based on the speed signal from the wheel speed sensor that detects the rotational state of the wheel, and based on the calculation results, pressurizes, Retention,
Alternatively, an electronic control circuit that outputs a command signal for depressurization (or only pressurization or depressurization) and a braking pressure piping system that connects the master cylinder and the wheel cylinder are provided, and the braking pressure from the master cylinder is transferred to the electronic control circuit. It is equipped with a hydraulic control unit that outputs controlled pressures for pressurization, holding, and depressurization based on command signals.

Hydraulic pressure control units can be of various types, such as a combination of two solenoid valves or a flow control valve and a solenoid valve or force, a to-off valve and an expansion valve, or an electric (R valve), and are generally used to supply control pressure. Each braking pressure system is equipped with a hydraulic pump, accumulator, reserve tank, etc.

When the brake pedal is depressed and anti-lock control starts, the system calculates the wheel speed, estimated vehicle speed, wheel deceleration, sling pressure, etc. based on the speed signal from the wheel speed sensor.
As a result, when the electronic control circuit determines that the wheels are about to lock, it outputs a residual pressure I command, and then issues a hold command to check the state of lock recovery, and when the long pressure recovers, it outputs a pressurization command again. To perform braking by making the most effective use of tire friction force.

In such a conventional anti-lock brake system, if the hydraulic pressure control unit for adjusting the hydraulic pressure fails, the failure can be detected by electrically checking the operation of the solenoid valve's drive lever. Alternatively, a method is generally used to electrically check whether the wheels are still unlocked even if the pressure reduction operation is carried out for a predetermined time or longer during a pressure reduction operation, which is one of the anti-lock brake control operations.

(Problem to be Solved by the Invention) However, in the former case of the failure detection method for the hydraulic control unit described above, only an electrical failure is detected, and for example, the solenoid of a solenoid valve is stuck. Failures due to mechanical factors such as these cannot be detected.

In the latter case, based on the wheel behavior measured by the wheel speed sensor, it is estimated that normal anti-lock control operation cycle is not being performed, and a failure due to mechanical factors is detected and an alarm is issued. be able to. However, this failure mode that can be alerted is only when the pressure is not reduced even though the mode should be reduced, and it is not possible to issue an alarm for the serious failure mode where the pressure is not pressurized even though it is in the mode where it should be pressurized. Can not. This is because the pressure to be applied in the pressurization mode varies to various values due to changes in the friction coefficient of the road surface, making it impossible to identify the failure mode.

This invention was made in view of the current state of the art regarding failure detection methods for the hydraulic pressure adjustment mechanism in the conventional anti-lock brake control device, and its purpose is to detect when the solenoid of a solenoid valve in a hydraulic pressure control unit is stuck. An object of the present invention is to provide an anti-lock brake control device having a failure detection means that can reliably detect failures caused by mechanical factors such as.

[Means to solve the problem]

Therefore, in this invention, as a means to solve the above problem, the braking pressure generated in the master cylinder when the brake pedal is depressed is adjusted and sent to the wheel cylinders. The wheel speed, wheel deceleration, estimated vehicle speed, slip amount, etc. are calculated and determined based on signals from one or more hydraulic pressure control units installed and a wheel speed sensor that detects the rotational state of each wheel. An electronic control circuit that outputs a pressure reduction or pressure increase command to the hydraulic pressure control unit when it detects a wheel locking tendency or a tendency to recover from locking, and a hydraulic pressure control unit that outputs a pressure reduction or pressure increase command to the hydraulic pressure control unit when it detects a wheel locking tendency or a tendency to recover from locking. and a differential pressure switch that detects the differential pressure of When it is detected that the detection continues for a predetermined period of time or more, an abnormality alarm is output to detect a failure of the hydraulic pressure control unit.

[Effect]

The anti-lock brake control device according to the present invention configured as described above can normally perform anti-lock control in the same way as conventional devices unless there is a failure in the hydraulic pressure control unit in the braking pressure piping system, and when non-anti-lock control is performed, it can perform normal anti-lock control. brake can be applied.

A differential pressure input signal from the differential pressure switch is sent to the electronic control circuit, and the electronic control circuit determines that the command signal from the electronic control circuit to the fluid pressure control unit is a pressurization command and that the differential pressure signal continues for a predetermined period of time or more. 0 mechanical These factors include things that cannot be immediately detected as electrical signals, such as a stuck spool, a clogged orifice, or a stuck solenoid.

Therefore, in such a case, a warning signal is output, for example, anti-lock control is stopped and safe braking is performed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic system diagram of an embodiment of an anti-lock brake control device having a failure detection means according to the present invention.

1 is the brake pedal, 2 is the master cylinder, and this
The two systems of braking pressure Pg and Pa generated are supplied to the wheel cylinders 4 of the left and right front wheels via the flow control valves 3, respectively, and the braking pressure pipes branched midway are used as It is also supplied to the rear wheels via the respective flow control valves 3.

The flow rate control valve 3 includes a spool 32 and a spring 33 that presses the spool 32 inside the valve body 31, and the spool 32 is provided with an orifice 34, and further has a solenoid valve 5 integrated therein as shown. When the solenoid valve 5 is opened during anti-lock control, the spool 32 is pushed down and the main flow path is cut off.
The discharge path communicates with the i5 magnetic valve 5, and the hydraulic pressure in the wheel cylinder 4 is returned to the pressurization source 6. 35 is the rear ply room, 3
6 is a decompression chamber, and 37 is a sleeve. P+, Pt
, P are the first boat, second boat, third boat of the spool 32, Pi s P (11% Pot is the inlet, the -th exit boat, the -exit boat, R-, R+, R2, respectively)
is an annular groove and two branch paths. Further, the pressurization source 6 includes a pump 61, a motor 62, and a reserve tank 63.

For the hydraulic pressure control unit shown in FIG. 1, in order to detect failures due to mechanical factors, a differential pressure switch 7 is added to detect the hydraulic pressure difference caused by the flow control valve 3 between the wheel cylinder 4 of the front wheel and the master cylinder 2. .7' and left and right braking pressure P
A differential pressure switch 8 for detecting the differential pressure between a and Ps' is provided. The differential pressure swing chias 7', 8 may be of a displacement type as shown in the second jump, or of various other types.

Reference numeral 10 denotes an electronic control circuit (ECU) that outputs a hydraulic pressure or pressurization command to the electromagnetic valve 5 of the hydraulic pressure control unit, and a schematic block diagram thereof is shown in FIG. Signals from wheel speed lines 81 to S4 that detect the rotational state of the wheels are sent to the A/D converter 11.
The signal is converted into a pulse signal by the pulse processing circuit 12, and then sent to the micro combinator 13 after being subjected to pulse processing by the pulse processing circuit 12.

The microcomputer 13 calculates the wheel speed, wheel deceleration, estimated vehicle speed, slip amount, etc. from the above signals, and when it detects a tendency of the wheels to lock or a tendency to recover from locking, it drives a pressure reduction or pressure increase command. Circuit 14. ~
14. It is sent to the solenoid valves 51-54 via. 14. ．． 14
□ indicates warning lamp WL and relay circuit 16, respectively.
This is the drive circuit.

In addition, the signals of the differential pressure switches 7.7', 8 are connected to the interface 146.14. ．． 14. The signal is inputted to the microcomputer 13 via. Generally, an electronic control circuit has a self-diagnosis function to detect whether the electrical operation in the circuit is normal or not, and when a failure occurs, the failure location, type of failure, etc. are stored in the failure code memory 15.

The above-mentioned anti-lock brake control device normally operates in the same manner as before, whether during anti-lock control or non-anti-lock control. That is, during non-antilock control, the braking pressure pm(p,') is applied to the inlet P1 of the IT control valve 3, the first boat P3, the rear ply chamber 35, the second boat P2, and the branch path R.
1, the main flow path passing through the annular groove R8 and the second outlet boat P0 is sent to the wheel cylinder 4.

During anti-lock control, when the solenoid valve 5 is opened, the spool 32 is
descends and the main flow is cut off, and the -th exit boat po+,
Annular groove Ro, branch path R2, third boat P1, decompression chamber 36
, solenoid valve 5, second outlet bow) A discharge path passing through PO2 is communicated with the low pressure side of the pressurization source 6, and the hydraulic pressure in the wheel cylinder 4 is reduced.

When the electromagnetic valve 5 is closed, a hydraulic pressure difference between the apply chamber 35 and the decompression chamber 36 remains due to the orifice 34, so that the spool 32 is pushed back by the spring 33 and rises, and the braking pressure P is again increased.

During such anti-lock control, when the differential pressure switch 7 detects the hydraulic pressure difference between the master cylinder 2 and the wheel cylinder 4 due to the flow control valve 3, the differential pressure switch 7 detects the cause if the hydraulic pressure difference exceeds a predetermined value. Detect whatever it is. The cause of the difference in fluid pressure is when a pressure reduction command is given to the flow control valve 3, or while the flow control valve is in operation after switching to a pressure increase command, or when the flow control valve 1 is in operation. This occurs when the magnetic valve malfunctions and normal control pressure cannot be applied.

Since the difference in hydraulic pressure between the former two is a normal operation of normal anti-lock control, it is necessary to detect it separately from the difference caused by a failure in the latter. In order to detect the latter failure, in this embodiment, the electronic control circuit 10 is provided with a differential pressure switch,
7' signals manually and microcomputer 1.
The following simple sub-programs are provided for the program for performing normal anti-lock control provided in 3.

As shown in Figure 4, anti-lock system? 111 is started, and the main program performs normal anti-lock control calculations and outputs commands for depressurization and pressurization based on the calculations, but an interrupt is generated at an appropriate timing in each cycle of execution of the program, and as shown in the figure. Make three judgments. Incidentally, since the differential pressure switches 7, 7' are provided independently, each differential pressure switch is determined by the blow-down subprogram. First, it is checked whether or not a differential pressure signal is input to the differential pressure switch 7 or 7'. If there is an input, the command signal to the solenoid valve 5 of the flow control valve 3 is a pressurization command, and then the differential pressure signal is checked. Checks whether the human power of the signal continues for more than a predetermined time.

child! The predetermined time can be, for example, a time sufficient to restore the pressure in the wheel cylinder, which has been reduced to the maximum by the flow control valve, to the maximum braking pressure generated by the maximum pedal effort.

When the command signal to the electromagnetic valve 5 of the flow control valve 3 is not a pressurization command, or even if it is a pressure signal, if the input of the differential pressure signal does not continue for a predetermined period of time or more, each state is normal anti-lock control operation. This is the hydraulic pressure difference caused by the Therefore, in this case, the flow control valve etc. are immediately determined to be normal and normal anti-lock control is continued.

If the above two conditions are met and the differential pressure signal continues for a predetermined time or longer, a mechanical failure has occurred in either the flow control valve or the solenoid valve, and the drive circuit 1
The warning lamp WL is turned on via 41 to give a warning. At the same time, the contents of this fault diagnosis are stored in the fault code memory 15 as a code.

In this example, a four-channel system is illustrated in which all four wheels are independently controlled by four flow control valves 3, but for simplicity, a differential pressure switch for the rear wheel flow control valve 3 is used. is omitted from the illustration.

Further, in the case of a three-channel system or a two-channel system, the number of differential pressure switches may be increased or decreased depending on each case.

In FIG. 1, a further differential pressure switch 8 is provided. This differential pressure switch 8 has braking pressures Ps, P+
Activates when the differential pressure between +' exceeds a predetermined value.

If the master cylinder 2 is normal, the braking pressures P and P.

are generally the same pressure, and no differential pressure occurs. Therefore, the differential pressure switch 8 detects a mechanical failure in the master cylinder 2 or a failure in any one of the braking pressure systems.

However, the differential pressure switch 8 is inoperative, and the differential pressure switch 7 (
If differential pressure switch 8 and 7 (or 7') are activated, there may be a failure in the hydraulic control unit, and if both differential pressure switches 8 and 7 (or 7') are activated, it is generally the master cylinder. This can be considered as the second failure. Therefore, when differential pressure is detected by differential pressure switch 8, differential pressure switch 7 (
or 7'), the failure detection and alarm are not performed.

[Effects] As explained in detail above, in this invention, the hydraulic pressure control unit detects a hydraulic pressure difference of a predetermined value or more between the piping parts between each wheel cylinder and the master cylinder in the braking pressure piping system using a differential pressure switch. However, the differential pressure signal is while the pressurization command is being output to the fluid pressure control unit.
The electronic control circuit then detects that the signal continues for a predetermined period of time to determine whether the failure is due to mechanical causes in the hydraulic control unit, and outputs an alarm when a failure is detected. Therefore, when a difficult-to-diagnose failure like the one described above occurs, it can be detected immediately and the brakes can be operated in a safer direction.

[Brief explanation of the drawing]

Fig. 1 is a schematic system diagram of an embodiment of an anti-lock brake control device according to the present invention, Fig. 2 is a schematic configuration diagram of a differential pressure switch, Fig. 3 is a block diagram of an electronic control circuit, and Fig. 4 is a subprogram diagram. FIG. 2 is a flowchart diagram. 1...brake pedal, 2...master cylinder, 3...flow control valve, 4...
...Wheel cylinder, 5...Solenoid valve,
6... Pressure source, 7.7', 8... Differential pressure switch, 10... Electronic control circuit, 13... Microcomputer, 15. ...
・・Fault code memory, WL・・Warning lamp, patent applicant
Sumitomo Electric Industries Co., Ltd. Agent Fumi Kamata

Claims (3)

[Claims] (1) At least one or more hydraulic pressure control units provided for each of at least two or more mutually independent braking pressure piping systems that adjust the braking pressure generated in the master cylinder when the brake pedal is depressed and send it to the wheel cylinders. Then, wheel speed, wheel deceleration, estimated vehicle speed, slip amount, etc. are calculated and calculated based on signals from wheel speed sensors that detect the rotational state of each wheel.As a result, the tendency of the vehicle to lock or recover from lock is detected. Then, it is equipped with an electronic control circuit that outputs a pressure reduction or pressure increase command to the hydraulic pressure control unit, and a differential pressure switch that detects a differential pressure of more than a predetermined value by the hydraulic pressure control unit between the master cylinder and wheel cylinder of each braking pressure system. When the electronic control circuit detects that the differential pressure above a predetermined pressure has been detected for a predetermined period or more, an abnormality alarm is output to detect a failure of the hydraulic control unit. An anti-lock brake control device having a failure detection means comprising: (2) The signal outputted by the electronic control circuit to the hydraulic pressure control unit is a pressure increase signal, and the signal of a differential pressure greater than a predetermined value detected by the differential pressure switch indicates a wheel whose pressure has been reduced to the maximum by the hydraulic pressure control unit. The malfunction according to claim 1, characterized in that the brake system is configured to output an alarm when it is detected that the cylinder pressure has been maintained for a sufficient time to restore the pressure to the maximum braking pressure generated by the maximum pedal force. Anti-lock brake control device having detection means. (3) In addition to the differential pressure switch, the electronic control circuit includes a second differential pressure switch that detects a differential pressure between corresponding braking pressure piping systems at a piping site between the hydraulic control unit and the master cylinder. If the second differential pressure switch detects a differential pressure above a predetermined value, the detection of the differential pressure by the first differential pressure switch and its alarm are cut off, and the second differential pressure switch detects a differential pressure above a predetermined value. The anti-lock brake control having failure detection means according to claim 1, wherein the first differential pressure switch detects the differential pressure and issues an alarm only when the differential pressure is not detected. Device.