JP3655385B2 - Brake control device for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle brake control device.
[0002]
[Prior art]
Conventionally, a pump is provided in the middle of a fluid passage that connects the master cylinder (or master reservoir) and the wheel cylinder of each wheel, and the brake fluid pressure of the wheel cylinder (master cylinder fluid) is determined according to the skid and slip state of the wheel. 2. Description of the Related Art There is known a vehicular braking control apparatus that can increase the hydraulic pressure of a wheel cylinder to an appropriate value by a combination of opening and closing of various solenoid valves.
[0003]
Further, Japanese Patent Laid-Open No. 2-169357 discloses a switching valve for opening and closing the liquid path in a liquid path connecting the suction side and the master cylinder side of the pump so that the liquid path is opened and closed as necessary. Thus, there is disclosed a braking control device configured so that the same pump can be used for both ABS control (anti-skid brake control) and TRC control (traction control control).
[0004]
[Problems to be solved by the invention]
In the ABS / TRC system sharing the self-priming pump disclosed in Japanese Patent Laid-Open No. 2-169357, after completion of the ABS operation or initial check, as shown in FIG. When the flag shown is turned on (pump motor relay is turned off), a pump drive stop command is output. On the other hand, since the switching valve remains closed, the master cylinder side and the suction side of the pump remain blocked. Therefore, a negative pressure state remains on the suction side of the pump.
[0005]
Further, for example, when the TRC control is activated, as shown in FIG. 5B, the switching valve is open until the TRC control is finished, and the flag indicating the end is turned on (the pump motor). The relay is turned off) and a pump drive stop command is issued. However, even if a pump drive stop command is issued, the pump does not stop immediately but continues to rotate for a while due to inertia. For this reason, as a result, a state in which the pump operates with the switching valve closed is formed, and the brake fluid between the switching valve blocking the pump suction side and the master cylinder side is still sucked into the pump, Negative pressure is generated in the liquid path.
[0006]
If such a negative pressure is left unattended, air dissolved in the brake fluid appears as bubbles, and the pump discharge response at the next ABS or TRC operation deteriorates.
[0007]
The present invention has been made in view of such a conventional problem, and provides a vehicular braking control device capable of preventing bubbles from being generated due to negative pressure in a liquid passage by driving a pump. This is the issue.
[0008]
[Means for Solving the Problems]
The present invention includes a control valve for opening and closing the first fluid passage provided in the first fluid passage communicating the suction side of the pump driven by one motor of the master cylinder or master reservoir, the discharge side of the pump A hydraulic pressure holding solenoid valve provided in a second fluid path communicating with the wheel cylinder of each wheel, and opening and closing the second fluid path; a master cylinder and a hydraulic pressure retaining solenoid valve upstream of the second fluid path; A master cut valve that is provided in a third fluid passage that communicates with the first fluid passage and opens and closes the third fluid passage, and communicates either one of the master cylinder or the master reservoir and the upstream side of the fluid pressure retaining solenoid valve of the second fluid passage. A pressure reducing valve that opens and closes the fifth liquid path and is provided in a fifth liquid path that connects the downstream side of the hydraulic pressure maintaining solenoid valve of the fourth liquid path and the downstream side of the switching valve of the first liquid path. It has bets, during the traction control, opening the switching valve, Masutaka The valve is closed, the solenoid valve for holding the hydraulic pressure is opened, the pressure reducing valve is closed, the pump is driven, and the brake fluid is passed through the first liquid path, the pump, and the second liquid path. The pressure in the wheel cylinder is increased by sending it to the wheel cylinder, the solenoid valve for holding the hydraulic pressure is closed, the pressure reducing valve is opened, the pump is driven, and the brake fluid in the wheel cylinder is supplied to the fifth fluid path, pump In the vehicular braking control device that controls the braking force applied to each wheel by reducing the wheel cylinder hydraulic pressure by recirculating through the fourth fluid path and adjusting the wheel cylinder hydraulic pressure, After the stop command is output to the motor driven during power control and the switching valve is closed, the means for determining that the pump has stopped with the switching valve closed and the pump stop When it is determined that By providing a means for a predetermined time opened, and is obtained by solving the above problems.
[0009]
In the traction control control, the switching valve is opened, the master cut valve is closed, the hydraulic pressure holding solenoid valve is opened, the pressure reducing valve is closed, the pump is driven, and the brake fluid is The hydraulic pressure of the wheel cylinder is increased by being sent to the wheel cylinder via the one liquid path, the pump, and the second liquid path, the hydraulic pressure holding electromagnetic valve is closed, the pressure reducing valve is opened, and the pump is When driven, the brake fluid of the wheel cylinder is recirculated through the fifth fluid passage, the pump, and the fourth fluid passage, so that the wheel cylinder fluid pressure is reduced and the wheel cylinder fluid pressure is adjusted. The braking force applied to the wheel is controlled. According to the present invention, after the stop command is output to the motor driving the pump during the braking force control and the switching valve is closed, the pump is stopped from the operating state with the switching valve closed. when it is determined that the state, by the switching valve provided in the first fluid passage for communicating the one of the suction side and the master cylinder or master reservoir of the pump and opening a predetermined time, said liquid passage It is possible to prevent the inside from becoming negative pressure and to prevent generation of bubbles.
According to the present invention, upon completion of the traction control control, the switching valve is closed and a stop command is output to the motor. At that time, a negative pressure may be generated between the switching valve of the first liquid passage and the pump, but the inside of the liquid passage is maintained at a negative pressure by opening the switching valve for a predetermined time after the pump is stopped. Therefore, the generation of bubbles can be prevented.
In the anti-skid control , the switching valve is closed, the master cut valve is opened, the hydraulic pressure holding solenoid valve is opened, the pressure reducing valve is closed, and the brake fluid in the master cylinder is supplied to the third fluid. The pressure in the wheel cylinder is increased by being sent to the wheel cylinder via the passage and the second fluid passage, the solenoid valve for holding the hydraulic pressure is closed, the pressure reducing valve is opened, and the pump is driven, brake fluid fifth fluid passage of the wheel cylinder, a pump, and a third fluid path wheel cylinder pressure is reduced by Rukoto refluxed through, by the wheel cylinder pressure is adjusted, added to each wheel The braking force applied is controlled. Therefore, the wheel cylinder hydraulic pressure cannot be appropriately reduced when the switching valve is opened. Therefore , when the anti-skid brake control is started while the switching valve is open for a predetermined time, the switching valve is closed to execute the control with priority.
In addition, the pump continues to rotate with inertia even after a stop command is output to the motor, but when a predetermined time has elapsed since the stop command was issued, it can be determined that the pump has completely stopped.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment, the means for detecting the transition to the stop state performs the detection when a predetermined time has elapsed since the pump stop command was output.
[0011]
As a result, the transition of the pump to the actual stop state can be easily detected, and the generation of bubbles can be prevented.
[0012]
Hereinafter, an example of a more specific embodiment of the present invention will be described in detail with reference to the drawings.
[0013]
FIG. 1 is a schematic configuration diagram of a vehicle brake control device according to a first embodiment of the present invention.
[0014]
In FIG. 1, when the brake pedal 2 is depressed, the booster 4 amplifies the stepping force, and the brake fluid pressure corresponding to the boosting action is applied to the first fluid chamber 6a and the second fluid chamber 6b of the master cylinder 6, respectively. Occur. The hydraulic pressure generated in the first fluid chamber 6a is transmitted from the first brake fluid passage 8 to the wheel cylinders 12 and 14 of the left front wheel FL and the right front wheel FR. The hydraulic pressure generated in the second fluid chamber 6b is transmitted from the second brake fluid passage 10 through the (known) P & B valve 16 (proportional and bypass valve) to the wheel cylinders 18 of the left rear wheel RL and the right rear wheel RR. 20 is transmitted.
[0015]
The first and second brake fluid passages 8 and 10 are separated from the fluid passages 22 and 24 and the fluid passages 26 and 28, respectively. The liquid passages 22, 24, 26, and 28 are provided with normally-open hydraulic pressure maintaining solenoid valves 30, 32, 34, and 36, respectively.
[0016]
The reservoir 38 is connected to the wheel cylinders 12 and 14 by liquid passages 42 and 44, respectively, and the reservoir 40 is connected to the wheel cylinders 18 and 20 by liquid passages 46 and 48, respectively. Each reservoir 38, 40 accumulates brake fluid of the wheel cylinders 12, 14, 18, 20 at the time of decompression.
[0017]
The liquid passages 42, 44, 46, 48 are provided with normally closed pressure reducing solenoid valves 50, 52, 54, 56, respectively. Each pressure reducing solenoid valve 50, 52, 54, 56 releases the brake fluid pressure of each wheel cylinder 12, 14, 18, 20 to the reservoirs 38, 40 during pressure reduction immediately before the wheel is locked, etc., to reduce the brake fluid pressure. .
[0018]
Brake fluid in the reservoirs 38, 40 is sucked into the reservoirs 38, 40 and the first and second brake fluid passages 8, 10, respectively, and is disposed near the master cylinder 6. Self-priming pumps 64 and 66 for circulating to the master reservoir 62 are provided. These self-priming pumps (hereinafter simply referred to as pumps) 64 and 66 are driven by a motor 68. In this embodiment, the pump 66 corresponds to the pump described in claim 1.
[0019]
A master cut valve 70 is disposed between the P & B valve 16 and the holding electromagnetic valve 34 in the second brake fluid passage 10. The master cut valve 70 is normally open, and when the brake pedal 2 is depressed, the brake fluid is transmitted to the wheel cylinders 18 and 20 through the master cut valve 70. On the other hand, it is closed during TRC control, and communication between the master cylinder 6 side and the wheel cylinders 18 and 20 side is cut off.
[0020]
A fluid path 72 is provided for returning the brake fluid sucked from the reservoir 40 by the pump 66 to the master reservoir 62. A first switching valve 74 and a pressure adjustment valve 76 are disposed in the liquid path 72. Further, the suction side of the master reservoir 62 and the pump 66 is in communication with a liquid path 78. The liquid passage 78 is provided with a second switching valve 80 (a switching valve referred to in claim 1).
[0021]
Both the first and second switching valves 74 and 80 are normally closed and are open during TRC control. During the TRC control, the pump 66 sucks the brake fluid from the master reservoir 62 via the second switching valve 80 and sends the brake fluid from the fluid passage 60 to the wheel cylinders 18 and 20 through the fluid passage 26 and the fluid passage 28 to increase the pressure. At this time, if the pressure applied to the wheel cylinders 18 and 20 becomes too high, the brake fluid is circulated to the master reservoir 62 via the first switching valve 74 and the pressure adjustment valve 76 in order to prevent the brake device from being damaged. The
[0022]
The holding solenoid valves 30, 32, 34, 36 and the pressure reducing solenoid valves 50, 52, 54, 56, the master cut valve 70, the first and second switching valves 74, 80, and the motors that drive the pumps 64, 66 68 and the like operate according to a command from an electronic control unit (ECU) 82. The electronic controller 82 also detects the operating state of the pump 66.
[0023]
The operation of this embodiment will be described below using the flowchart of FIG.
[0024]
In step 100, it is determined whether the ABS control has been completed. In step 110, it is determined whether the TRC control has been completed. In step 120, whether the initial check for checking the operation of each solenoid has been completed. It is determined whether or not.
[0025]
If any one of these determinations in Steps 100 to 120 is Yes, the process proceeds to Step 130. If both are No, the process immediately returns. When both are No, an operation command is output to the motor 68, and the pumps 64 and 66 are driven by the motor 68.
[0026]
In step 130, it is determined whether ABS control or TRC control is being performed. If any control is in progress, the process returns. Otherwise, the process proceeds to the next step 140.
[0027]
In step 140, it is determined whether or not a predetermined time t1 (4 seconds in this embodiment) has elapsed since the motor stop command was output (after the motor relay was turned off). This is because the pumps 64 and 66 continue to rotate due to inertia even when the motor relay is turned off, and a predetermined time is required until the motor relay is completely stopped. At this time, if the second switching valve 80 is closed, the pump 66 continues to rotate, and a negative pressure is generated in the liquid path 78 between the second switching valve 80 and the pump 66. If this is left unattended, bubbles are generated. There is a fear.
[0028]
When the predetermined time t1 has elapsed, it is determined that the pumps 64 and 66 have stopped, and the second switching valve 80 is opened in the next step 150.
[0029]
In the next step 160, it is determined whether or not ABS control is started. If the ABS control is not started, it is determined in step 170 whether or not a predetermined time t2 (0.2 seconds in the present embodiment) has elapsed since the second switching valve 80 was opened. If the predetermined time t2 has not elapsed, the process returns to step 160, and if the predetermined time t2 has elapsed or the ABS control is started, the second switching valve 80 is closed in step 180.
[0030]
Thus, by stopping the pump 66 and opening the second switching valve 80 for a predetermined time t2, the negative pressure generated in the liquid path 78 can be eliminated, and the generation of bubbles can be prevented. When the ABS control is started before the predetermined time t2 elapses, the second switching valve 80 is immediately closed and the ABS control is executed with priority.
[0031]
The operation of the present embodiment as described above is shown in FIGS.
[0032]
When the ABS control, the TRC control, or the initial check is completed and the flag indicating the completion is turned on, the motor relay is turned off to stop driving the pumps 64 and 66. When a predetermined time t1 (4 seconds) has elapsed since the motor relay is turned off, it is determined that the pump 66 has completely stopped, and the second switching valve 80 is opened for a predetermined time t2 (0.2 seconds).
[0033]
As described above, when the ABS is entered while the second switching valve 80 is opened for the predetermined time t2, the second switching valve 80 is immediately opened as shown in the flow from step 160 to step 180. The control is stopped and executed again after the ABS control is completed.
[0034]
Next, a second embodiment of the present invention will be described.
[0035]
FIG. 4 is a schematic configuration diagram of the vehicle brake control device according to the second embodiment.
[0036]
In the first embodiment described above, the pump 66 sucks the brake fluid from the master reservoir 62 and returns it from the pressure adjustment valve 76 to the master reservoir 62. However, in the second embodiment, the pumps 164 and 166 The brake fluid is sucked from the master cylinder 106 and returned to the master cylinder 106 from the pressure regulating valves 176 and 176 ′. Therefore, in this embodiment, both the pumps 164 and 166 correspond to the pumps described in claim 1.
[0037]
As shown in FIG. 4, the present embodiment employs X piping. That is, the fluid path 122 and the fluid path 128 are separated from the first brake fluid path 108 and communicate with the wheel cylinder 112 of the left front wheel FL and the wheel cylinder 120 of the right rear wheel RR, respectively, and from the second brake fluid path 110 to the fluid path. 124 and the liquid passage 126 are separated and communicate with the wheel cylinder 114 of the right front wheel FR and the wheel cylinder 118 of the left rear wheel RL, respectively. That is, the first brake fluid passage 108 and the second brake fluid passage 110 are arranged symmetrically.
[0038]
The (self-priming) pumps 164 and 166 are respectively switched from the first liquid chamber 106a and the second liquid chamber 106b of the master cylinder 106 through switching valves 180 'and 180 (both corresponding to the switching valve in claim 1). The brake fluid is self-primed from the fluid passages 178 'and 178. In the present embodiment, the master cut valves 170 'and 170 and the pressure adjustment valves 176' and 176 are arranged in parallel, respectively. When the master cut valves 170 'and 170 are closed, the pressure adjustment valve 176 is provided. 'And 176 return the brake fluid to the master cylinder 106. Reference numerals 117 and 117 ′ are known P valves (proportional valves) that adjust the hydraulic pressures of the wheel cylinders 118 and 120 of the rear wheels RL and RR. Other configurations are the same as those of the first embodiment, and corresponding members are denoted by the same reference numerals in the last two digits, and detailed description thereof is omitted.
[0039]
The operation of the second embodiment is basically the same as that of the first embodiment.
[0040]
That is, in order to stop the driving of the pumps 164 and 166, after a predetermined time has elapsed since the stop command is output to the motor 168, the switching valves 180 'and 180 are opened for a predetermined time, and the negative pressure in the liquid passages 178' and 178 Is to prevent the generation of bubbles.
[0041]
As described above, in the present invention, the brake fluid is self-primed from the master reservoir and returned from the pressure adjustment valve to the master cylinder, or the brake fluid is self-primed from the master cylinder and returned from the pressure adjustment valve to the master reservoir. The same applies.
[0042]
The means for detecting the stop of the pump is not limited to the one in the present embodiment, and the rotation of the pump may be directly detected, and various means can be used.
[0043]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent generation of bubbles due to negative pressure in the pipe by opening the switching valve for a predetermined time after determining that the pump has completely stopped.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a vehicular braking control apparatus according to a first embodiment of the present invention. FIG. 2 is a flowchart showing the operation of the first embodiment. FIG. 3 is a diagram showing the operation of the first embodiment. FIG. 4 is a schematic configuration diagram showing a vehicle brake control device according to a second embodiment of the present invention. FIG. 5 is a diagram showing the operation of a conventional brake control device.
2, 102 ... Brake pedal 4, 104 ... Booster 6, 106 ... Master cylinder 8, 108 ... First fluid passage 10, 110 ... Second fluid passage 12, 112, 14, 114, 18, 118, 20, 120 ... Wheel Cylinder 16 ... P & B valve 22, 24, 26, 28, 42, 44, 46, 48, 58, 60, 72, 78, 122, 124, 126, 128, 142, 144, 146, 148, 158, 160, 172 178, 178 '... liquid passages 30, 32, 34, 36 ... holding solenoid valves 50, 52, 54, 56 ... pressure reducing solenoid valves 62, 162 ... master reservoirs 64, 66, 164, 166 ... self-priming pump 70 , 170, 170 '... master cut valve 74 ... first switching valve 76, 176, 176' ... pressure regulating valve 80, 180, 180 '... second switching valve 82, 182 ... electronic control Unit (ECU)

Claims (4)

A switching valve that is provided in a first fluid passage that communicates either one of the master cylinder or the master reservoir and a suction side of a pump driven by a motor , opens and closes the first fluid passage , a discharge side of the pump, and each wheel A hydraulic pressure retaining solenoid valve provided in a second fluid passage communicating with the wheel cylinder of the second fluid passage; and opening and closing the second fluid passage; upstream of the master cylinder and the fluid pressure retaining solenoid valve of the second fluid passage; A master cut valve provided in a third fluid passage communicating with the first fluid passage, and opening and closing the third fluid passage; one of the master cylinder and the master reservoir; and the upstream side of the fluid pressure maintaining solenoid valve of the second fluid passage; Provided in a fifth liquid passage communicating with the fourth liquid passage communicating with the second hydraulic passage, the fluid pressure holding solenoid valve downstream of the second liquid passage, and the switching valve downstream of the first liquid passage. It has a pressure reducing valve for opening and closing the liquid passage, and
During traction control control, the switching valve is opened, the master cut valve is closed, the hydraulic pressure holding solenoid valve is opened, the pressure reducing valve is closed, and the pump is driven. The brake fluid is sent to the wheel cylinder through the first fluid passage, the pump, and the second fluid passage to increase the wheel cylinder fluid pressure, and the fluid pressure holding solenoid valve is closed, The pressure reducing valve is opened, the pump is driven, and the wheel cylinder hydraulic pressure is reduced by returning the brake fluid of the wheel cylinder through the fifth fluid passage, the pump, and the fourth fluid passage. In the vehicle braking control device for controlling the braking force applied to each wheel by adjusting the wheel cylinder hydraulic pressure,
After the stop command is output to the motor driven during the braking force control and the switching valve is closed, it is determined that the pump is stopped with the switching valve closed. Means,
And a means for opening the switching valve for a predetermined time when it is determined that the pump is stopped.   2. The vehicular braking control apparatus according to claim 1, wherein when the traction control control ends, the switching valve is closed and a stop command is output to the motor. The vehicle brake control apparatus, when the anti-skid control, closed the switching valve, thereby opening the master cut valve, it opens the fluid pressure retaining solenoid valves, closing the pressure reducing valve Then, the brake fluid of the master cylinder is sent to the wheel cylinder through the third fluid passage and the second fluid passage to increase the wheel cylinder fluid pressure, and the fluid pressure maintaining solenoid valve is closed. And opening the pressure-reducing valve, driving the pump, and returning the brake fluid of the wheel cylinder through the fifth fluid path, the pump, and the third fluid path. By reducing the pressure and adjusting the wheel cylinder hydraulic pressure, the braking force applied to each wheel is controlled,
The vehicular braking control device according to claim 1 or 2, wherein the switching valve closes the switching valve when anti-skid brake control is started while the valve is open for the predetermined time. .   The means for determining that the pump has been stopped determines that the pump has been stopped when a predetermined time has elapsed since a stop command was issued to the motor. The vehicle brake control device according to any one of the preceding claims.

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