JP2006069372A - Inspection method for pump in vehicle brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce vibration and sound caused by a pulse when an electric motor MR of a pump is electrically checked. <P>SOLUTION: When a vehicle speed arrives at a predetermined speed, a driving signal is firstly given to normally closed type first and second solenoid valves USV, EV to make the respective valves closed. At that time, at least one valve of the respective valves is positioned at midway of communication/shutoff without making it fully closed and is made to such a state that a brake operation fluid can flow in response to generation of a differential pressure on the front and rear sides of the valve. Further, a pump is slightly operated in response to starting of the vehicle and the remaining liquid in a reservoir is preferably reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pump inspection technique in a vehicle brake control device, and more particularly to a technique effective as a countermeasure against pulsation that occurs during the inspection.

  As a vehicle brake control device, anti-lock brake control for controlling locking at the time of braking, traction control for controlling slip at the time of acceleration of a vehicle, or lateral instability of a traveling vehicle is eliminated. For example, there is a device for performing control related to the driver's brake operation or control unrelated to the driver's brake operation. Generally, these brake control devices are capable of receiving a brake fluid that is loosened from the wheel cylinder during brake control, and pumping the brake fluid in the reservoir to the wheel cylinder by driving an electric motor. Provide a pump that can. And since it is an apparatus regarding the vehicle which drive | works, it is necessary to perform the electrical check about the pump of an electric motor drive similarly to other electrical components, and to ensure the safety. For example, the following patent documents show examples of conventional pump check technology (so-called initial check).

In JP-A-5-170072, when the driver performs a brake pedal operation (depression), the pump is not electrically checked. That is, by restricting or selecting the timing of the initial check, the pulsation generated at the time of the check is prevented from being transmitted to the driver through the brake pedal, thereby preventing the driver from feeling uncomfortable.

Japanese Patent Application Laid-Open No. 8-150911 discloses a technique for reducing unpleasant vibration and sound caused by pulsation without restricting the electrical check timing of the pump.

  As in Patent Document 1, selecting the electrical check timing of the pump is effective in blocking vibration transmitted through the pedal. However, the vibrations and sounds associated with pump checks are not only transmitted through the pedal. What is transmitted to the passenger compartment through brake piping or toe board cannot be ignored. Therefore, what is important is that, as in Patent Document 2, vibration and sound should be reduced when the pump is electrically checked.

  In Patent Document 2, when the pump is electrically checked, the two on-off valves located on the brake pipe are shut off so that vibration is not transmitted from the on-off valves to the wheel cylinder side and the master cylinder side. In addition, since each on-off valve is shut off, there is no restriction on the check timing of the pump. However, since the on-off valve, especially the on-off valve located between the pump and the master cylinder, is in the shut-off state, if the driver performs a brake operation at that time, the brake pedal will be in the state of stepping on the plate (trying to depress the pedal) May not be able to be depressed), and the driver may not be able to operate the brakes. Checking the pump is only a short time, but it should be avoided that the brake pedal is depressed because it is a problem while the vehicle is running.

Accordingly, an object of the present invention is basically to provide a pump inspection technique that can effectively reduce vibration and sound caused by pulsation when the pump is electrically checked.
Another object of the present invention is to provide a technique capable of effectively avoiding a situation in which the brake pedal enters a state where the brake pedal is depressed.
Other objects of the present invention will become clear from the following description.

  This type of vehicle brake control device includes a first solenoid valve located between the pump and the master cylinder on a brake pipe connecting the master cylinder and the wheel cylinder, and a second solenoid located between the pump and the wheel cylinder. A solenoid valve. Each of the first and second solenoid valves is an electromagnetic on-off valve that receives an electric signal and controls communication / cut-off by electromagnetic force. In the present invention, during the inspection of the pump, the first solenoid valve and the second solenoid valve are controlled to be closed in order to prevent transmission of pulsation accompanying the pump operation. In addition, when performing the drive control, at least one of the first and second solenoid valves is located in the middle of the communication / blocking, unlike the state in which the communication of the hydraulic fluid is completely blocked. A differential pressure is generated before and after the valve so that the brake fluid can flow.

  When controlling the opening and closing of the solenoid valve, which is an on-off valve, the electromagnetic driving force of the solenoid valve can be sequentially changed by controlling the drive signal applied. For example, if the current value applied to the solenoid of the solenoid valve is increased by pulse width modulation, the electromagnetic force due to excitation gradually increases, overcoming the force of the valve spring, and switching the normally open solenoid valve from open to closed. be able to. At that time, for example, the duty value can be reduced to several tens of percent by performing control so that the force accompanying the electromagnetic force and the force of the valve spring are balanced. The solenoid valve in this state is positioned in the middle of communication / interruption, and is a state in which brake hydraulic fluid can flow by generating a differential pressure across the solenoid valves. In the present invention, at least one of the first and second solenoid valves is controlled to such an intermediate state of opening / closing.

  At least one of (a) when controlling only the first solenoid valve, (b) when controlling only the second solenoid valve, and (c) both the first and second solenoid valves. In the case of such control, three cases are meant. In any of these three cases, the solenoid valve controlled in such a manner acts to flow the hydraulic fluid by the differential pressure across the front and back, so to speak, to flow while being throttled, so that the pulsation associated with the pump operation is attenuated. Can do. Further, in each of the cases (a) and (c) in which the first solenoid valve that is in the middle of communicating between the master cylinder and the pump is controlled, it is possible to avoid the situation where the plate stepping state described above is brought about.

  Further, various experiments have revealed that the hydraulic fluid remaining in the reservoir in the circuit has a tendency to particularly increase the pulsation associated with the pump operation and the vibration and sound resulting therefrom. Measurement results of each part affected by pulsation (for example, measurement results over time such as vibration of the main body of the brake control device, vibration of the master cylinder and booster, brake pipe pressure connected to the wheel cylinder, vibration of the toe board) The first measurement value is the largest, and the second and subsequent measurement values tend to be considerably smaller than the first measurement value. Therefore, in order to further effectively reduce the pulsation accompanying the pump operation and the vibration and sound caused by the pulsation, it is effective to reduce the working fluid remaining in the reservoir prior to the inspection of the pump. Specifically, it is possible to employ a method of driving the electric motor of the pump for a very short time, that is, for a time shorter than the drive signal at the time of pump inspection. In practice, it is possible to drive the electric motor prior to the inspection in response to turning on the ignition switch when starting the vehicle. When the vehicle starts to travel and reaches a predetermined speed or higher (for example, 14 km / h or higher), the electric motor for pump inspection is driven.

  FIG. 1 is a circuit diagram showing an example of a vehicle brake control device to which the present invention is applied. First, this circuit diagram is clarified, and it is mentioned where the pulsation accompanying the pump operation has an adverse effect. Such a vehicle brake control device itself is already known as shown in, for example, Japanese translations of PCT publication No. 2003-507258.

  The vehicle brake control device has both functions of an anti-lock control accompanying a brake pedal operation by a driver and a brake control during automatic braking unrelated to the driver's brake operation. The basic components are a tandem master cylinder 10 that is a brake hydraulic pressure generation source, four wheel cylinders 201, 202, 203, 204 provided corresponding to four wheels, and wheel cylinders 201-204. The hydraulic pressure control unit 50 is located between the master cylinder 10. The master cylinder 10 is connected to the brake pedal 102 through the booster 101. Normally, the pedal 102 is located on the vehicle compartment side including the cab, and the master cylinder 10 and the booster 101 are located on the engine room side separated by a toe board (not shown).

  The tandem master cylinder 10 has two independent ports 11 and 12, and accordingly, there are two pipe connection ports 511 and 512 in the housing of the hydraulic pressure control unit 50. Further, the housing of the hydraulic pressure control unit 50 includes four different pipe connection ports 521, 522, 523, and 524 according to the four wheel cylinders 201 to 204. Since the hydraulic pressure control unit 50 and the master cylinder 10 and the wheel cylinders 201 to 204 communicate with each other by piping, pulsation generated in the hydraulic pressure control unit 50 is transmitted through the piping to the master cylinder 10 side and the wheel cylinders 201 to 204 side. Can be communicated to. Therefore, in order to prevent vibrations and sounds caused by pulsation from causing anxiety to the driver, the pulsation generated by the hydraulic pressure control unit 50 is prevented from being transmitted to the outside of the hydraulic pressure control unit 50. It is effective to do.

  The hydraulic pressure control unit 50 includes four normally open solenoid valves (second solenoid valves) EV and four normally closed solenoid valves AV according to the four wheel cylinders 201 to 204. The hydraulic pressure control unit 50 includes an electric motor MR drive pump 30. The pump 30 is a double plunger pump, and applies brake fluid pressure to each wheel cylinder 201 to 204 through each normally open solenoid valve (second solenoid valve) EV, and each normally closed solenoid valve AV. The brake fluid pressure of each wheel cylinder 201-204 can be relaxed to the reservoir 70 through It will be appreciated that when the pump 30 is operated, the pump 30 draws up the hydraulic fluid in the reservoir 70 or circuit and sends the hydraulic fluid to the master cylinder 10 side and the wheel cylinders 201-204 side. This is a cause of transmitting the pulsation accompanying the pump operation to the outside of the hydraulic pressure control unit 50.

  The hydraulic pressure control unit 50 further includes a normally open solenoid valve (first solenoid valve) USV between the master cylinder 10 and the discharge side of the pump 30, as well as the suction side of the pump 30 and the master cylinder 10. A normally closed solenoid valve HSV is included in between. These solenoid valves are valves corresponding to automatic brakes. When the pump 30 is operated and the master cylinder 10 is not operated, the normally closed solenoid valve HSV is opened, and the normally open solenoid valve (first valve) 1 solenoid valve) USV is closed.

  The vehicle brake control device also includes an electronic control unit (not shown) having a microcomputer function for controlling each solenoid valve and pump. In the present invention, the electronic control unit is used to perform an electrical check of each solenoid valve included in the hydraulic pressure control unit and a check of the electric motor MR of the pump 30 by software. FIG. 2 shows in particular a timing chart for checking the electric motor MR of the pump 30. The contents of the inspection according to the present invention will be described with reference to FIG. First, as described above, EV is a holding solenoid valve, AV is a pressure reducing solenoid valve, FL is a left front wheel, RR is a right rear wheel, and FR is a reference numeral shown in FIG. The right front wheel and RL indicate the left rear wheel, respectively. Therefore, FLEV is a solenoid valve for holding the left front wheel, RREV is for holding the right rear wheel, FREV is for holding the right front wheel, and RLEV is a solenoid valve for holding the left rear wheel. Again, USV is a normally open solenoid valve (first solenoid valve), and MR is an electric motor for driving the pump 30.

  Each solenoid valve and the electric motor MR of the pump 30 are checked while the vehicle is running. Here, after each solenoid valve is checked at a very low speed when the vehicle starts to travel, the electric motor MR of the pump 30 is checked at a time T14 when the vehicle speed reaches 14 km / h, for example. As described above, prior to the inspection, in order to reduce the hydraulic fluid remaining in the reservoir 70, for example, a driving signal for 10 ms is given at the time T0 of the ON signal of the ignition switch for starting the vehicle. The 10 ms drive signal is a shorter time signal than the drive signal over 20 ms, for example, at the inspection time T14 of the pump 30. Preferably, for the 10 ms drive signal at the time T0 of the ignition switch ON signal, a pulse signal of 3 ms is first applied in order to overcome the starting torque and enable energization check, followed by a pulse signal of 1 ms. Give it twice. When the pump 30 is driven for such a short period of time, the normally open first and second solenoid valves USV and EV do not need to be closed.

  When the vehicle speed reaches 14 km / h, first, drive signals are given to the normally open first and second solenoid valves USV and EV to close the valves. In this case, at least one of the normally open first and second solenoid valves USV and EV is completely closed (that is, no liquid flows even if a differential pressure is generated before and after the valve). For example, the duty value is set to several tens of percent by pulse width modulation. At that time, the valve that performs such control is positioned in the middle of the communication / blocking, and a pressure difference is generated before and after each of the solenoid valves so that the brake hydraulic fluid can flow. The drive signals for the solenoid valves USV and EV are preferably continued so as to extend before and after the drive signal applied to the electric motor MR when the pump 30 is inspected. This is because the response delay of the operation of the pump 30 can be covered thereby.

  In the present invention, it is preferable to control so that at least the first solenoid valve USV leading to the master cylinder 10 side is positioned in the middle of the communication / blocking as described above, in order to avoid the state where the plate is stepped on. . However, it can also be applied to avoid the plate stepping state by not checking the pump operation when the brake signal is detected.

It is a circuit diagram which shows an example of the vehicle brake control apparatus to which this invention is applied. It is an example of the timing chart of the pump test | inspection by this invention.

Explanation of symbols

10 master cylinder 201-204 wheel cylinder 30 pump MR electric motor 50 hydraulic control unit EV second solenoid valve USV first solenoid valve 70 reservoir

Claims (5)

A master cylinder that generates brake fluid pressure by pedal operation by the driver, a wheel cylinder that communicates with the master cylinder through brake piping, a reservoir that can receive brake hydraulic fluid loosened from the wheel cylinder, and the reservoir A pump capable of pressure-feeding the brake hydraulic fluid to the wheel cylinder by driving an electric motor, and located on the brake pipe between the pump and the master cylinder and communicating between the pump and the master cylinder side A first solenoid valve that controls the shutoff and a second solenoid valve that is located on the brake pipe and between the pump and the wheel cylinder and controls the communication / shutoff between the pump and the wheel cylinder. A vehicle brake control device comprising: When testing the operation, and performing under the conditions of the following (a) ~ (d), testing method of the pump in a vehicle brake control system.
(A) A drive signal is given to the electric motor of the pump (b) A first valve drive signal is given to the first solenoid valve so as to be closed (c) A second solenoid valve is brought to a closed state (D) when at least one of the first solenoid valve and the second solenoid valve is closed by the first valve drive signal or / and the second valve drive signal, the hydraulic fluid Unlike the state in which the communication is completely blocked, the brake is located in the middle of the communication / blocking and a differential pressure is generated on the brake pipe before and after the first solenoid valve and / or the second solenoid valve. It is in a state where hydraulic fluid can flow The duration of the valve drive signal for the first and second solenoid valves is longer than the duration of the drive signal of the electric motor, and continues to extend before and after the drive signal of the electric motor. The inspection method of the pump according to claim 1. The pump inspection method according to claim 1, wherein both the first and second solenoid valves are controlled by pulse width modulation. The pump of claim 1, wherein, prior to testing the pump, the electric motor of the pump is driven for a short time, that is, for a time shorter than the drive signal at the time of the test, in order to reduce the working fluid remaining in the reservoir. Inspection method. In conjunction with turning on the ignition switch of the vehicle, the electric motor is driven prior to the inspection, and when the vehicle exceeds a predetermined speed, the electric motor for driving the pump is driven. The method for inspecting a pump according to claim 4.

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