JP2009023643A - Vehicle brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent dragging feeling of a brake from being given to a driver in completion of brake assist control. <P>SOLUTION: In completion processing of the brake assist control, a brake liquid is returned to a regulator RG through a conduit MR, and the brake liquid is returned to a master cylinder MC through a conduit MF. Thereby, the brake liquid used for boosting a liquid pressure of a bulk-up amount can be quickly returned, and the brake liquid pressure applied to respective wheel cylinders Wfr-Wrl can quickly approach M/C pressure inherently generated. Accordingly, in completion of brake assist control, the dragging feeling of the brake can be prevented from being given to the driver. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle brake control device that executes a brake assist control that executes a brake assist control that generates a braking force larger than that during a normal brake when an emergency brake operation is performed.

  Conventionally, for example, Patent Literature 1 discloses a braking force control device capable of executing brake assist control. FIGS. 11 and 12 are schematic diagrams showing brake fluid transmission paths during and at the end of the brake assist control in the conventional braking force control device, respectively.

  In the brake assist control, for example, when the braking force of the brake pedal BP exceeds a predetermined value and when it is desired to generate a braking force larger than that during normal braking, the four wheels FR to RL are used as control target wheels. A brake fluid pressure corresponding to a predetermined raising amount is applied to the wheel cylinders Wfr to Wrl corresponding to the wheels.

  Specifically, at the time of brake assist control, energization of the electromagnetic on-off valves STR, SREC, SMCF, and SREA is all turned on. That is, as shown in FIG. 11, the electromagnetic on-off valve STR is in a communication state, the electromagnetic on-off valve SREC is in a shut-off state, the electromagnetic on-off valve SMCF is in a cut-off state, and the electromagnetic on-off valve SREA is in a communication state. The energization of the pressure increase control valves PC1 to PC4 and the pressure reduction control valves PC5 to PC8 corresponding to the wheel to be controlled is appropriately switched ON and OFF.

  At this time, since the electromagnetic on-off valves SREC and SMCF are in the cut-off state, the master cylinder MC and the wheel cylinders Wfr to Wrl are not connected. On the other hand, since the electromagnetic on-off valves STR and SREA are in communication, the accumulator Acc is connected to the wheel cylinders Wfr to Wrl.

  Therefore, as indicated by the arrows in the figure, the brake fluid pressure accumulated in the accumulator Acc is transmitted through the pipelines AM, AC, MF1, MF2, MR1, MR2 and the electromagnetic on-off valves STR, SREA. Then, the pressure increase control valves PC1 to PC4 and the pressure reduction control valves PC5 to PC8 corresponding to the control target wheel are appropriately switched between a communication state and a cutoff state, and transmitted to the wheel cylinders Wfr to Wrl corresponding to the control target wheel. As a result, it is possible to execute brake assist control in which a braking force in which a predetermined amount of raising is added to the wheels to be controlled in the four wheels FR to RL is generated.

  On the other hand, at the end of the brake assist control, the end control is performed in order to gradually increase the braking force corresponding to the raised amount to zero. Specifically, since the brake fluid is excessively supplied to the wheel cylinders Wfr to Wrl in order to increase the braking force by the raising amount, the brake fluid supplied to the wheel cylinders Wfr to Wrl. The amount is returned to the normal brake level. At this time, considering that the braking force is generated by using the brake fluid pressure accumulated in the accumulator Acc during the brake assist control, the consumed brake fluid is returned to the place where the brake fluid is consumed. This is because the brake fluid on the accumulator Acc and regulator RG side, which is the rear system, is consumed, so that the brake fluid is returned to the rear system in principle, and the amount of brake fluid consumed by the brake assist control is This is because when the brake fluid is returned to the front master cylinder MC, the brake pedal BP is pushed back, and the driver may feel uncomfortable. However, since the brake fluid cannot be returned when the pressure in the accumulator Acc is high, the brake fluid is returned toward the regulator RG.

  Specifically, the electromagnetic on-off valves STR and SREC are turned off, and the electromagnetic on-off valves SREA and SMCF are turned on. That is, as shown in FIG. 12, the electromagnetic on-off valves STR and SMCF are in a shut-off state, and the electromagnetic on-off valves SREC and SREA are in a communication state. As a result, as indicated by the arrows in the figure, the brake fluid supplied from the accumulator Acc side is returned from the wheel cylinders Wfr to Wrl to the regulator RG side through the pipelines MF1, MF2, MR1, MR2, AC, and MR. At this time, the electromagnetic on-off valve SMCF is shut off, so that the brake fluid is not returned to the master cylinder MC through the pipe MF.

Thereafter, after a predetermined time when it is assumed that the brake fluid has been returned until it finally becomes equal to the brake fluid pressure generated in the master cylinder MC (hereinafter referred to as M / C pressure), the electromagnetic opening / closing valve SMCF, Turn off all SREC, STR and SREA. As a result, the electromagnetic on-off valves STR and SREA are shut off and the electromagnetic on-off valves SREC and SMCF are in communication, and the M / C pressure is applied to the front wheel FR and the wheel cylinders Wfr and Wfl on the FL side, and is generated in the regulator RG. The brake fluid pressure thus applied is returned to the normal brake operation in which the brake fluid pressure is applied to the rear wheel RR, RL side wheel cylinders Wrr, Wrl.
JP 2006-35889 A

  However, when the brake assist control end control is executed as described above, since all the brake fluid returned to the regulator RG passes through the electromagnetic on-off valve SREC, the brake fluid cannot be quickly returned. For this reason, when the driver suddenly returns the brake pedal BP after the brake assist control is executed, the brake fluid pressure equal to or higher than the M / C pressure is still applied to each wheel cylinder Wfr to Wrl. It becomes a state. As a result, there is a problem in that the driver feels the brake dragging (residual pressure) as if the braking force is generated even though the brake pedal BP is returned.

In particular, when brake assist control is executed in a large vehicle, the amount of brake fluid consumed is increased, and it takes time to return that amount of brake fluid to the regulator RG. For example, when brake assist control is executed on a dry road surface, the brake fluid pressure applied to the wheel cylinders Wfr to Wrl is about 10 MPa, and the brake fluid consumption is about 5 cm ³ . This amount of consumption is very large, about twice that of medium to large vehicles of ordinary passenger cars.

  In view of the above, an object of the present invention is to prevent the driver from feeling dragged at the end of brake assist control.

  In order to achieve the above object, according to the first aspect of the present invention, the control means (10) includes means (110) for determining whether or not a start condition for brake assist control is satisfied, and a start condition for brake assist control. A means (130) for instructing the first and second electromagnetic on-off valves to be in a shut-off state and the third and fourth electromagnetic on-off valves to be in communication with each other; Means (140) for determining whether or not the end condition of the assist control is satisfied, and when the end condition is satisfied, as the end process of the brake assist control, the third electromagnetic on-off valve is turned off and the first electromagnetic And a means (160) for instructing both the on-off valve and the second electromagnetic on-off valve to be in communication with each other.

  If it does in this way, at the time of an end process, while returning brake fluid to a regulator (RG) through the 2nd pipe (MR), brake fluid can be returned to a master cylinder (MC) through the 1st pipe (MF). . For this reason, the brake fluid used for increasing the hydraulic pressure corresponding to the raised amount can be quickly returned, and the brake fluid pressure that is applied to each of the wheel cylinders Wfr to Wrl can be quickly generated. It becomes possible to approach the pressure. As a result, it is possible to prevent the driver from feeling dragged at the end of the brake assist control.

  In particular, a vehicle that consumes a lot of brake fluid to execute brake assist control, such as a large vehicle, may give the driver a feeling of dragging the brake, but this prevents it. It becomes possible to do.

  The invention according to claim 2 is characterized in that the control means maintains the fourth electromagnetic on-off valve in the communicating state during the termination process.

  Thus, the front system and the rear system can be connected through the fourth conduit (AC) by maintaining the fourth electromagnetic on-off valve in a communicating state. For this reason, when the brake fluid of either one of the systems is quickly returned to the regulator or the master cylinder, it is possible to return the brake fluid of the system that is delayed in returning the brake fluid to the other system through the fourth pipeline. Become. For this reason, it is possible to prevent the brake fluid return time from being shifted between the front system and the rear system, and to return the brake fluid more quickly.

  In this case, as shown in claim 3, in order to put the fourth electromagnetic on-off valve in a shut-off state after the time required for returning the brake fluid has elapsed, it is determined that the end condition is satisfied in the control means. It is preferable to provide means (200) for instructing to turn off the fourth electromagnetic on-off valve after a predetermined time has elapsed.

  Specifically, as shown in claim 4, when the end condition is satisfied, the control means can instruct the first electromagnetic on-off valve and the second electromagnetic on-off valve to communicate with each other at the same time. According to a fifth aspect of the present invention, when the end condition is satisfied, the second electromagnetic on-off valve may be in a communication state, and then the first electromagnetic on-off valve may be instructed to be in a communication state. According to a sixth aspect of the present invention, when the end condition is satisfied, the second electromagnetic on-off valve can be in a communication state, and an instruction to repeatedly switch the first electromagnetic on-off valve between the communication state and the cutoff state can be issued. .

  According to the seventh aspect of the present invention, when the termination condition is satisfied, as the brake assist control termination process, the third electromagnetic on-off valve is brought into a shut-off state, the second electromagnetic on-off valve is brought into a communication state, and In addition, there is provided means for instructing to bring the first electromagnetic on-off valve into the communication state with a predetermined delay time delayed from the timing at which the second electromagnetic on-off valve is in the communication state.

  Thus, the delay time can be provided at the timing at which the first electromagnetic on-off valve is in communication with the timing at which the second electromagnetic on-off valve is in communication. As a result, it is possible to prevent the driver from feeling dragged while reducing the driver's uncomfortable feeling caused by pushing back the brake pedal BP.

  In the invention according to claim 8, the delay time when the first electromagnetic on-off valve is brought into the communication state by delaying the second electromagnetic on-off valve by a predetermined time from the timing at which the second electromagnetic on-off valve is in the communication state It is characterized by having a means for setting it small.

  The feeling of dragging of the brake is felt when the brake operating member is suddenly returned. Therefore, the larger the return speed of the brake operation member, the smaller the delay time is set, and the brake fluid is returned to the master cylinder from the first electromagnetic on / off valve at an early stage to reduce the brake drag feeling and return the brake operation member. When the speed is low, the delay time can be increased to reduce the uncomfortable feeling of brake push-back, and the delay time can be made to correspond to the return speed of the brake operation member.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
FIG. 1 shows a hydraulic circuit configuration of a vehicle brake control device to which an embodiment of the present invention is applied. Hereinafter, the configuration of the vehicle brake control device of the present embodiment will be described with reference to this figure.

  As shown in this figure, the vehicle brake control device is provided with a master cylinder MC and a regulator RG, which are driven in accordance with the operation of the brake pedal BP. An auxiliary hydraulic pressure source AS is connected to the regulator RG.

  The auxiliary hydraulic pressure source AS is provided with a low-pressure reservoir RS, and generates auxiliary hydraulic pressure using the brake fluid stored in the low-pressure reservoir RS. Specifically, the auxiliary hydraulic pressure source AS is provided with a hydraulic pump HP and an accumulator Acc. The hydraulic pump HP is driven by the electric motor M, and sucks and discharges the brake fluid in the low pressure reservoir RS. The brake fluid discharged from the hydraulic pump HP is supplied to the accumulator Acc, and the inside of the accumulator Acc is accumulated at a desired pressure. The regulator hydraulic pressure is detected by, for example, a pressure sensor 11 described later, and is always kept within a predetermined range by driving the electric motor M.

  The electric motor M is driven in response to the brake fluid pressure (fluid pressure) in the accumulator Acc being lower than a predetermined lower limit value, so that the inside of the accumulator Acc is boosted. Is stopped in response to the fluid pressure exceeding a predetermined upper limit. In this way, the brake fluid pressure accumulated in the accumulator Acc is controlled to be within a predetermined range, and this brake fluid pressure is supplied to the regulator RG as an output fluid pressure.

  The low-pressure reservoir RS is also connected to the regulator RG and the master cylinder MC so that the brake fluid stored in the low-pressure reservoir RS can be supplied to the regulator RG and the master cylinder MC.

  The regulator RG receives the output hydraulic pressure of the auxiliary hydraulic pressure source AS and adjusts the output hydraulic pressure of the master cylinder MC to a regulator hydraulic pressure proportional to the pilot hydraulic pressure. A pipe connecting the regulator RG and the accumulator Acc is provided with a check valve CV6, and only pressure transmission from the accumulator Acc side to the regulator RG side is performed, and the brake fluid flows in the reverse direction. There is no structure. Note that the basic configuration of the regulator RG is well known, and thus the description thereof is omitted here.

  A front-wheel side pipe line (first pipe line) MF connecting the master cylinder MC and each of the wheel cylinders Wfr, Wfl of the front wheels FR, FL has an electromagnetic on-off valve (first valve) constituted by a two-port two-position valve. An electromagnetic on-off valve (SMCF) is provided. On the downstream side of the electromagnetic opening / closing valve SMCF, the pipe MF is branched into two pipes MF1 and MF2, and pressure increase control valves (first and second pressure increase control valves) are respectively provided in the pipes MF1 and MF2. PC1 and PC2 are provided. And between each pressure-increasing control valve PC1, PC2 and the wheel cylinders (first and second wheel cylinders) Wfr, Wfl of the front wheels FR, FL are connected to the pipeline RC connected to the low pressure reservoir RS through the pipelines RC1, RC2. Has been. The pipelines RC1 and RC2 are respectively provided with decompression control valves (first and second decompression control valves) PC5 and PC6. The decompression control valves PC5 and PC6 cut off the communication between the pipelines RC1 and RC2. Is to be controlled.

  The electromagnetic on-off valve SMCF is in a valve position where the master cylinder MC is connected to each of the wheel cylinders Wfr, Wfl of the front wheels FR, FL through the pipelines MF, MF1, MF2 when not energized. When the energization is performed, the valve position is such that the master cylinder MC is shut off from the wheel cylinders Wfr and Wfl in front of the vehicle.

  In addition, the pipeline (second pipeline) MR connecting the master cylinder MC and the wheel cylinders (third and fourth wheel cylinders) Wrr, Wrl, etc. of the rear wheels RR, RL is composed of a two-port two-position valve. An electromagnetic on-off valve (second electromagnetic on-off valve) SREC is provided. The pipe MR is branched into pipes MR1 and MR2 on the downstream side of the electromagnetic on-off valve SREC, and each of the branched pipes MR1 and MR2 has a pressure increase control valve (third pressure increase control). Valve) PC3 and pressure increase control valve (fourth pressure increase control valve) PC4 are provided. The pressure-increasing control valves PC3 and PC4 and the wheel cylinders Wrr and Wrl of the rear wheels RR and RL are connected to a pipe RC connected to the low-pressure reservoir RS through the pipes RC3 and RC4. Each of the pipes RC3 and RC4 is provided with a pressure reduction control valve (third pressure reduction control valve) PC7 and a pressure reduction control valve (fourth pressure reduction control valve) PC8.

  The auxiliary hydraulic pressure source AS is connected to the downstream side of the electromagnetic on-off valve SREC via a pipe line (third pipe) AM, and the pipe AM is connected to an electromagnetic on-off valve (second valve) constituted by a two-port two-position valve. 3 electromagnetic on-off valve) STR is provided.

  In addition, between the electromagnetic on-off valve SREC and each of the pressure increase control valves PC3 and PC4 in the pipe MR, the electromagnetic on-off valve SMCF and each pressure increase in the pipe MF are connected via a pipe (fourth pipe) AC. Control valves PC1 and PC2 are connected. This line AC is provided with an electromagnetic on-off valve (fourth electromagnetic on-off valve) SREA composed of a two-port two-position valve so that the communication cut-off of the line AC can be controlled by this electromagnetic on-off valve SREA. It has become.

  Note that check valves CV1 to CV4 are connected in parallel to each pressure increase control valve PC1 to PC4, and each check pressure valve CV1 to CV4 is connected to the downstream side of each pressure increase control valve PC1 to PC4 (wheel cylinder Wfr). Only the flow of brake fluid from the Wfl side to the upstream side is allowed. A check valve CV5 is also connected in parallel to the electromagnetic opening / closing valve SREC. Even if the electromagnetic on-off valve SREC is shut off by the control by the check valve CV5, if the pressure generated by the brake operation of the driver wins, the brake from the upstream side (regulator RG side) to the downstream side of the electromagnetic on-off valve SREC Only liquid flow is allowed.

  Further, the vehicle brake control device is provided with pressure sensors 11 to 13 for detecting the brake fluid pressure at each part in the hydraulic circuit. The pressure sensor 11 is for detecting the brake fluid pressure accumulated in the accumulator Acc. The pressure sensor 12 is for detecting the brake fluid pressure generated in the master cylinder MC, and is provided upstream of the electromagnetic on-off valve SREC in the pipe MR. The pressure sensor 13 is for detecting the brake fluid pressure generated upstream of the electromagnetic on-off valve SMCF, that is, the M / C pressure.

  The vehicle brake control device configured as described above includes a brake ECU 10 (see FIG. 2) corresponding to a control unit. The relationship between input and output of signals to the brake ECU 10 is shown in FIG. That is, the detection signals of the pressure sensors 11 to 13 are input, and drive signals are output from the brake ECU 10 to the various valves SMCF, SREC, STR, SREA, PC1 to PC8 and the electric motor M based on the detection signals. Is done. Thus, the regulator hydraulic pressure is controlled to be maintained within a predetermined range, and the brake hydraulic pressure applied to the wheel cylinders Wfr to Wrl is controlled.

  Specifically, the various valves SMCF, SREC, STR, SREA, and PC1 to PC8 are set to the illustrated positions when the solenoid is not energized, and the solenoid is energized. During operation, the valve position is set to a position different from the illustrated position. Then, by adjusting the valve positions of the various valves SMCF, SREC, STR, SREA, and PC1 to PC8 by energizing the solenoid, brake assist control and the like are executed not only during normal braking.

  Next, brake assist control by the vehicle brake control device configured as described above will be described. FIG. 3 shows a flowchart of brake assist control processing executed by the brake ECU 10, and FIG. 4 shows various valves during normal braking, during brake assist control, and during brake assist control end processing (hereinafter simply referred to as end processing). The figure showing the operating state of is shown. 5 and 6 show the brake fluid transmission path during the brake assist control and the end process. With reference to these drawings, in addition to the details of the brake assist control process, the normal brake and the brake assist control are performed. The operation at the end processing will be described.

  As shown in FIG. 3, in step 100, the M / C pressure is detected based on the detection signal of the pressure sensor 13, and in step 110, whether or not the brake assist control start condition is satisfied, that is, larger than that during normal braking. It is determined whether or not a braking force is to be generated. Here, the brake assist control start condition is that the M / C pressure exceeds a predetermined threshold value P1. In addition, as the brake assist control start condition, various other well-known conditions such as that the depression force of the brake pedal BP exceeds a threshold value can be applied.

  If a negative determination is made in step 110, the routine proceeds to step 120 to perform normal braking without brake assist control, and the normal mode is set. As a result, the energization of the electromagnetic on-off valves STR, SREC, SMCF, and SREA are all turned off, and the operation during normal braking is performed.

  That is, when the energization of the electromagnetic on-off valves STR, SREC, SMCF, and SREA is all turned off, the electromagnetic on-off valve STR is in the shut-off state, the electromagnetic on-off valve SREC is in the communication state, the electromagnetic on-off valve SMCF is in the communication state, and the electromagnetic on-off valve The SREA is in a cut-off state. In addition, since the energization to the pressure increase control valves PC1 to PC4 and the pressure reduction control valves PC5 to PC8 remains OFF, the pressure increase control valves PC1 to PC4 are in a communication state, and the pressure reduction control valves PC5 to PC8 are in a cutoff state. .

  For this reason, since the electromagnetic on-off valve STR is shut off, the brake fluid pressure accumulated in the accumulator Acc is not transmitted to the wheel cylinders Wfr to Wrl. Since the electromagnetic on-off valve SMCF and the electromagnetic on-off valve SREC are in communication, the brake fluid pressure generated in the master cylinder MC is transmitted to the wheel cylinders Wfr, Wfl through the electromagnetic on-off valve SMCF. Further, the brake fluid pressure generated in the regulator RG is transmitted to the wheel cylinders Wrr and Wrl through the electromagnetic on-off valve SREC.

  On the other hand, if an affirmative determination is made in step 110, the process proceeds to step 130, where brake assist control is started and a flag indicating that brake assist control is being performed is set. That is, with the four wheels FR to RL being controlled wheels, the electromagnetic on-off valve STR is applied as shown in FIG. 4 in order to apply a brake fluid pressure corresponding to a predetermined raised amount to the wheel cylinders Wfr to Wrl corresponding to the controlled wheels. , SREC, SMCF, and SREA are all turned on, and the brake assist control is performed.

  In this way, when the energization of the electromagnetic on-off valves STR, SREC, SMCF, and SREA is all turned on, the electromagnetic on-off valve STR is in a communicating state, the electromagnetic on-off valve SREC is in an off state, the electromagnetic on-off valve SMCF is in an off state, The valve SREA is in a communication state. At this time, the energization to the pressure increase control valves PC1 to PC4 and the pressure reduction control valves PC5 to PC8 corresponding to the wheel to be controlled is appropriately switched ON and OFF.

  In this case, since the electromagnetic on-off valves STR and SREA are in communication, the accumulator Acc is connected to the wheel cylinders Wfr to Wrl.

  Therefore, as shown in FIG. 5, the brake fluid pressure accumulated in the accumulator Acc is transmitted through the electromagnetic on-off valves STR and SREA. Then, the pressure increase control valves PC1 to PC4 and the pressure reduction control valves PC5 to PC8 corresponding to the control target wheel are appropriately switched between a communication state and a cutoff state, and transmitted to the wheel cylinders Wfr to Wrl corresponding to the control target wheel. For this reason, braking force is generated in the wheels to be controlled in the four wheels FR to RL, and the pressure obtained by adding the raised amount to the M / C pressure is applied to each wheel cylinder Wfr to Wrl. Become.

  Since the electromagnetic on-off valves SREC and SMCF are in the cut-off state, the master cylinder MC and the wheel cylinders Wfr to Wrl are not connected. However, the hydraulic pressure generated in the regulator RG due to the depression of the brake pedal BP is appropriately transmitted through the check valve CV5.

  Then, the process proceeds to step 140, and it is determined whether or not the brake assist control end condition is satisfied. For example, when the driver depresses the brake pedal BP, when the driver depresses the brake pedal BP, or when the M / C pressure becomes smaller than a certain value (a value equal to or less than the threshold value P1 described above). May end the brake assist control. Also, the brake assist control may be terminated when the M / C pressure increases to a pressure generated during the brake assist control (a value obtained by adding the raised amount to the M / C pressure during the brake assist control). Therefore, when any of these conditions is satisfied, it is determined that the brake assist control end condition is satisfied. If a negative determination is made here, the process returns to step 130 to continue the brake assist control. If an affirmative determination is made, the process proceeds to step 150.

  In step 150, it is determined whether or not to execute end processing. In the end processing, when the amount of increase is added to the M / C pressure when the brake assist control is ended, the amount of increase is quickly eliminated, and the actually generated M / C pressure is Necessary for returning to the braking force. For example, when the M / C pressure increases to a pressure generated during brake assist control, it is not necessary to perform end processing. Therefore, if a negative determination is made here, the routine proceeds to step 120 where the normal mode is set and the flag indicating that the brake assist control is being performed is reset. If an affirmative determination is made here, an end process shown in step 160 and thereafter is executed.

  Specifically, in step 160, the energization of the electromagnetic on-off valves STR, SREC, and SMCF are all turned off. However, energization of the electromagnetic on-off valve SREA is turned on while the brake assist control is being performed.

  As a result, the electromagnetic on-off valve STR is cut off, the electromagnetic on-off valve SREC is in communication, the electromagnetic on-off valve SMCF is in communication, and the electromagnetic on-off valve SREA is in communication. At this time, the energization of the pressure increase control valves PC1 to PC4 and the pressure reduction control valves PC5 to PC8 corresponding to the wheels to be controlled is turned off, the pressure increase control valves PC1 to PC4 are in communication, and the pressure reduction control valves PC5 to PC8 are It will be in the cut-off state.

  Therefore, as shown in FIG. 6, the brake fluid transmitted to each of the wheel cylinders Wfr to Wrl is returned to the regulator RG through the pipe MR in which the electromagnetic open / close valve SREC is in communication, and the electromagnetic open / close valve SMCF is in communication. It is also returned to the master cylinder MC through the pipe line MF which is in a state. For this reason, the brake fluid can be returned to the master cylinder MC through the pipeline MF, compared with the case where it is returned to the regulator RG only through the pipeline MR as in the prior art. Therefore, the brake fluid used for the operation can be returned, and the brake fluid pressure applied to the wheel cylinders Wfr to Wrl can be quickly brought close to the originally generated M / C pressure. As a result, it is possible to prevent the driver from feeling dragged at the end of the brake assist control.

  Further, at the time of this termination control, the front and rear systems are connected through the pipe line AC by keeping the electromagnetic on-off valve SREA in the ON state to be in a communicating state. For this reason, when the brake fluid of one of the systems is quickly returned to the regulator RG or the master cylinder MC, the brake fluid of the system that is delayed in returning the brake fluid can be returned to the other system through the pipeline AC. It becomes. For this reason, it is possible to prevent the brake fluid return time from being shifted between the front system and the rear system, and to return the brake fluid more quickly.

  Here, as described above, during the brake assist control, the brake fluid of the accumulator Acc, that is, the rear brake fluid is transmitted to the wheel cylinders Wfr to Wrl of the front wheels FR, FL and the rear wheels RR, RL. In principle, the brake fluid should be returned to That is, since the amount of brake fluid consumed by the brake assist control is large, when the brake fluid is returned to the master cylinder MC that is the front system, the brake pedal BP is pushed back, which may give the driver a sense of discomfort. However, when both the front system and the rear system are released as in this embodiment, the brake fluid is returned to the rear system where the brake fluid has been consumed, so that not all is returned to the master cylinder MC. Absent. For this reason, the amount of brake fluid to be returned is reduced compared with the case of returning the brake fluid only to the master cylinder MC, and the brake pedal BP is pushed back, and the driver does not feel uncomfortable.

  When such an operation is performed, the process proceeds to step 170, the count value T of a counter (not shown) provided in the brake ECU 10 is reset, and the process proceeds to step 180 to determine whether the count value T exceeds the threshold A or not. Determine. The threshold A is the time required for the brake fluid pressure applied to each wheel cylinder Wfr to Wrl to be substantially lowered to the originally generated M / C pressure by returning the brake fluid corresponding to the above-described raised amount. This means the count number corresponding to. For this reason, the operation proceeds to step 190 until the count value T exceeds the threshold value A, and the operation of incrementing the count value T of the counter is repeated. By turning off the valve SREA, the shut-off state is set, the state is returned to the state where the front system and the rear system are not connected, and the flag indicating that the brake assist control is being performed is reset.

  As a result, when the brake fluid pressure applied to each wheel cylinder Wfr to Wrl becomes the M / C pressure that is substantially generated, it is possible to return to the same state as in the normal mode shown in step 120, and to the driver. It becomes possible to shift to the normal brake without giving a sense of incongruity.

  FIG. 7 shows a timing chart at the end processing when the brake assist control is executed as described above. As shown in this figure, during the brake assist control, a flag indicating that the brake assist control is being performed is set, and energization of the electromagnetic on-off valves STR, SREC, SREA, and SMCF is all ON. It becomes. When the brake assist control end condition is satisfied (step 140) and it is determined that the end process control is to be executed, the energization of all the electromagnetic on-off valves STR, SREC, and SMCF is turned off and the electromagnetic on-off valve SREA is turned on. Only energization of is turned on. Thereafter, when the count value T of the counter reaches the threshold value A, the energization of the electromagnetic on-off valve SREA is also turned off, and the state shifts to a state similar to the normal mode.

  As described above, in the vehicle brake control device of the present embodiment, the brake fluid is returned to the regulator RG through the pipeline MR and the brake fluid is returned to the master cylinder MC through the pipeline MF during the termination process. For this reason, the brake fluid used for increasing the hydraulic pressure corresponding to the raised amount can be quickly returned, and the brake fluid pressure that is applied to each of the wheel cylinders Wfr to Wrl can be quickly generated. It becomes possible to approach the pressure. As a result, it is possible to prevent the driver from feeling dragged at the end of the brake assist control.

  In particular, a vehicle that consumes a lot of brake fluid to perform brake assist control, such as a large vehicle, may give the driver a feeling of dragging the brake. It becomes possible to prevent it.

(Second Embodiment)
A second embodiment of the present invention will be described. In the present embodiment, in the prior art in which the electromagnetic on-off valve SMC is not opened, a brake feeling is felt when the brake pedal BP is suddenly returned, and in the first embodiment, the driver pushes back the brake pedal BP. The control method shown in step 160 is changed from the first embodiment, paying attention to the fact that the uncomfortable feeling felt is felt stronger than when the brake pedal BP is returned relatively slowly, particularly when the brake pedal BP is returned suddenly. Since other aspects are the same as those of the first embodiment, only different portions will be described.

Only when the electromagnetic on-off valve SMCF is opened without opening the electromagnetic on-off valve SMCF, the brake feeling is felt when the brake pedal BP is suddenly returned. Although the brake pedal BP is rapidly returned, the braking force is generated because the W / C pressure remains large, and the driver feels dragging. Therefore, only in that case, the electromagnetic on-off valve SMCF is brought into an early communication state. Here, the determination that the brake pedal BP is suddenly returned may be performed based on the change speed of the M / C pressure detected based on the detection signal of the pressure sensor 13. Conversely, when the brake pedal BP is slowly returned, there should be no feeling of drag regardless of the communication timing of the electromagnetic on-off valve SMCF. At that time, only the electromagnetic on-off valve SREC is turned off (communication state) and the electromagnetic The on-off valve SMCF does not turn off energization (communication state) and returns the brake fluid only to the regulator RG side to reduce the pressure. Then, after the predetermined delay time T _{DLY has} elapsed, for example, after the passage of Ams in FIG. 10, the electromagnetic on-off valve SMCF is also turned off to enter the communication state.

The delay time T _DLY when the energization of the electromagnetic on-off valve SMCF to the electromagnetic on-off valve SREC at this time is turned off can be set according to the return speed of the brake pedal BP, for example, a value corresponding to the return speed of the brake pedal BP Can be set according to the change rate ΔP / sec of the M / C pressure. That is, when the brake pedal BP is suddenly returned, there is little discomfort for the driver even if the brake pedal BP is pushed back by the brake pressure, but it is easy to feel when the brake pedal BP is returned relatively slowly. In consideration of the driver's uncomfortable feeling due to the brake pedal BP being pushed back, the timing at which the electromagnetic on-off valve SMCF is brought into communication is delayed for a predetermined time according to the change speed ΔP / sec. The change rate ΔP / sec of the M / C pressure can be set to the maximum change rate when the brake pedal is returned, for example.

8 and 9 are maps showing an example of the relationship of the delay time T _DLY to the change rate of the M / C pressure. Creating these maps are based on the knowledge of the relationship between the delay time and the relationship of the uncomfortable feeling that delay time T _DLY and the brake is returned T _DLY and brake dragging feeling. That is, the uncomfortable feeling is if the speed back of the brake pedal BP is high a small degree be felt regardless of the delay time T _DLY, when returning the brake pedal BP relatively slowly, large as the delay time T _DLY is reduced felt. Further, the brake drag feeling is felt as the delay speed T _DLY increases when the return speed of the brake pedal BP is large, and feels regardless of the delay time T _DLY when the brake pedal BP is returned relatively slowly. The degree to which it is done is small.

Therefore, as shown in FIG. 8, if the brake pedal BP is suddenly returned and the change rate ΔP / sec of the M / C pressure is equal to or greater than ΔP _H / sec, the delay time T _{DLY is set} to 0, and the change rate The delay time T _DLY is gradually lengthened as ΔP / sec becomes smaller, and when the change time ΔP / sec falls below a predetermined lower limit value ΔP _L / sec, the delay time T _DLY is set to a constant maximum delay time T _DLYmax . can do. As shown in FIG. 9, when the change rate ΔP / sec of the M / C pressure is equal to or greater than ΔP _H / sec, the delay time T _{DLY is set} to 0, and the change rate ΔP / sec is changed from ΔP _H / sec. [Delta] P _L / sec during the longer gradually delay time T _DLY between about change rate [Delta] P / sec decreases the delay time T _DLY 1 to T _DLY 2, time-varying [Delta] P / sec predetermined lower limit value [Delta] P _L / Sec or less, the delay time T _DLY can be set to the maximum delay time T _DLYmax which is a constant value. The delay time T _DLY 1 is a value greater than 0, and the delay time T _DLYmax is a value greater than the delay time T _DLY 2. That is, when the change rate ΔP / sec is between ΔP _H / sec and ΔP _L / sec, the change rate ΔP / sec may be a discontinuous value when ΔP _H / sec or ΔP _L / sec.

As shown in these _{figures, the} delay time T _DLY can be set to decrease as the return speed of the brake pedal BP increases, and the delay time T _DLY corresponding to the return speed of the brake pedal BP can be obtained. Thereby, the brake drag feeling given to the driver can be reduced. Further, as the return speed of the brake pedal BP decreases, the delay time _TDLY can be increased to reduce the uncomfortable feeling of brake push-back.

By the way, if the brake pedal BP has already been released, the driver will not feel uncomfortable when the brake pedal BP is pushed back. Therefore, even when the delay time T _DLY has not elapsed, if the brake pedal BP has already been released, the electromagnetic on-off valve SMCF is turned off to establish a communication state. For example, if the stop switch is off, it can be determined that the brake pedal BP has already been released.

  FIG. 10 is a timing chart at the time of termination processing when the brake assist control as in the present embodiment is executed.

As shown in this figure, when it is determined that the brake assist control end condition is satisfied and the end process control is to be executed, first, the energization of the electromagnetic on-off valves STR and SREC is all turned off, and the electromagnetic on-off valve SREA is turned off. The energization to is kept ON. At this time, the energization of the electromagnetic on-off valve SMCF is still ON. When the delay time T _DLY has elapsed, it is energized also solenoid valve SMCF is turned OFF, the communicating state.

As described above, the timing at which the energization of the electromagnetic on-off valve SMCF is turned off with respect to the timing at which the energization of the electromagnetic on-off valve SREC is turned off can be set by providing the delay time T _DLY . As a result, it is possible to prevent the driver from feeling dragged while reducing the driver's uncomfortable feeling caused by pushing back the brake pedal BP.

(Other embodiments)
In the first embodiment, the electromagnetic open / close valves SREC and SMCF are simultaneously turned off and in the communication state during the termination process. However, the electromagnetic open / close valve SMCF may be switched ON / OFF repeatedly by duty control. Alternatively, the counter may be turned off for a certain time shorter than the time until the count value T reaches the threshold value A.

  In the above embodiment, the detection value of the pressure sensor 12 is assumed to be equal to the M / C pressure, and the detection value of the pressure sensor 12 can be substituted without the pressure sensor 13.

In the first embodiment, the electromagnetic on-off valve SMCF is in communication with the electromagnetic on-off valve SREC regardless of the return speed of the brake pedal BP. In the second embodiment, the electromagnetic on-off valve is set in accordance with the return speed of the brake pedal BP. the opening timing of SMCF has a delay time T _DLY provided against opening timing of the electromagnetic on-off valve SPEC is variable. However, the present invention is not limited to this, and a delay time T _DLY that provides the opening timing of the electromagnetic on-off valve SMCF with respect to the opening timing of the electromagnetic on-off valve SPEC regardless of the brake return speed may be set.

  The steps shown in each figure correspond to means for executing various processes.

It is a figure which shows the hydraulic circuit structure of the brake control apparatus for vehicles concerning 1st Embodiment of this invention. It is the block diagram which showed the input / output relationship of the signal with respect to brake ECU. It is a flowchart of the brake assist control process which brake ECU performs. It is a chart showing the operating states of various valves during normal braking, during brake assist control, and during termination processing. It is the schematic diagram which showed the transmission path | route of the brake fluid in brake assist control. It is the schematic diagram which showed the transmission path | route of the brake fluid at the time of completion | finish processing. It is a timing chart at the time of the end process in the case of performing brake assist control. It is the map which showed an example of the relationship of delay time _TDLY with respect to the change speed of M / C pressure. It is the map which showed an example of the relationship of delay time _TDLY with respect to the change speed of M / C pressure. It is a timing chart at the time of the end processing in the case of performing brake assist control explained in a 2nd embodiment of the present invention. It is the schematic diagram which showed the transmission path | route of the brake fluid in brake assist control by the conventional braking force control apparatus. It is the schematic diagram which showed the transmission path | route of the brake fluid at the time of brake assist control completion | finish by the conventional braking force control apparatus.

Explanation of symbols

  AS ... auxiliary hydraulic pressure source, HP ... hydraulic pump, M ... electric motor, Acc ... accumulator, RG ... regulator, MC ... master cylinder, RS ... low pressure reservoir, BP ... brake pedal, STR, SREC, SMCF, SREA ... electromagnetic Open / close valve, PC1 to PC4 ... pressure increase control valve, PC5 to PC8 ... pressure reduction control valve, Wfr to Wrl ... wheel cylinder, MF, MR, AM, AC ... pipe, 10 ... brake ECU, 11-13 ... pressure sensor

Claims (8)

A reservoir (RS) mounted on the vehicle and storing brake fluid;
A hydraulic pump (HP) for boosting and discharging the brake fluid stored in the reservoir to a predetermined pressure;
An accumulator (Acc) for accumulating the discharge hydraulic pressure of the hydraulic pump;
A master cylinder (MC) that generates a brake fluid pressure according to the operation amount of the brake operation member (BP);
A regulator (RG) to which the brake fluid pressure accumulated in the accumulator is transmitted;
A first electromagnetic on-off valve (SMCF) is provided to generate braking force on the master cylinder and the first and second wheels (FR, FL) through the first electromagnetic on-off valve. Are connected to the first and second wheel cylinders (Wfr, Wfl), and are divided into two pipes (MF, MF1, MF2)
A second electromagnetic on-off valve (SREC) is provided for generating a braking force on the regulator and the third and fourth wheels (RR, RL) as rear wheels via the second electromagnetic on-off valve. Are connected to the third and fourth wheel cylinders (Wrr, Wrl), and are branched into two on the third and fourth wheel cylinder side from the second electromagnetic on-off valve (MR, MR1, MR2)
A third electromagnetic on-off valve (STR) is provided, and is accumulated in the accumulator between the second electromagnetic on-off valve and the third and fourth wheel cylinders in the second pipe through the third electromagnetic on-off valve. A third pipe (AM) for guiding the brake fluid pressure;
A fourth electromagnetic on-off valve (SREA), through the fourth electromagnetic on-off valve, between the first electromagnetic on-off valve and the first and second wheel cylinders in the first pipe line, and the second pipe line; A fourth pipe (AC) for connecting the second electromagnetic on-off valve and the third and fourth wheel cylinders in
Control for setting the flow path of the brake fluid by driving the fluid pressure pump and controlling the fluid pressure of the accumulator to be within a predetermined range and controlling the first to fourth electromagnetic on-off valves. Means (10),
The control means includes
Brake assist control in which the hydraulic pressure of the accumulator (Acc) exceeding the brake hydraulic pressure corresponding to the operation amount of the brake operating member (BP) is applied to any of the first to fourth wheel cylinders (Wfr to Wrl). Means (110) for determining whether or not a start condition is satisfied;
When the brake assist control start condition is satisfied, the first and second electromagnetic on / off valves are shut off and the third and fourth electromagnetic on / off valves are in communication to execute the brake assist control. Means for instructing (130);
Means (140) for determining whether or not an end condition of the brake assist control is satisfied;
When the termination condition is satisfied, as the brake assist control termination process, the third electromagnetic on-off valve is turned off and the first electromagnetic on-off valve and the second electromagnetic on-off valve are both in communication. And a vehicle brake control device characterized by comprising: means (160) for instructing this.   2. The vehicle brake control device according to claim 1, wherein the control unit maintains the fourth electromagnetic on-off valve in a communicating state during the termination process.   The said control means is provided with the means (200) which instruct | indicates that the said 4th electromagnetic on-off valve shall be made into the interruption | blocking state after predetermined time progress, after determining that the said completion | finish conditions were satisfy | filled. The vehicle brake control device described.   4. The control device according to claim 1, wherein when the termination condition is satisfied, the control unit instructs the first electromagnetic on-off valve and the second electromagnetic on-off valve to be in communication with each other simultaneously. 5. The vehicle brake control device described in 1.   2. The control unit according to claim 1, wherein when the termination condition is satisfied, the control unit instructs the first electromagnetic on-off valve to be in a communication state after the second electromagnetic on-off valve is in a communication state. 4. The vehicle brake control device according to any one of 3.   The control means, when the termination condition is satisfied, sets the second electromagnetic opening / closing valve in a communicating state and gives an instruction to repeatedly switch the first electromagnetic opening / closing valve between a communicating state and a blocking state. The vehicle brake control device according to any one of claims 1 to 3. A reservoir (RS) mounted on the vehicle and storing brake fluid;
A hydraulic pump (HP) for boosting and discharging the brake fluid stored in the reservoir to a predetermined pressure;
An accumulator (Acc) for accumulating the discharge hydraulic pressure of the hydraulic pump;
A master cylinder (MC) that generates a brake fluid pressure according to the operation amount of the brake operation member (BP);
A regulator (RG) to which the brake fluid pressure accumulated in the accumulator is transmitted;
A first electromagnetic on-off valve (SMCF) is provided to generate braking force on the master cylinder and the first and second wheels (FR, FL) through the first electromagnetic on-off valve. Are connected to the first and second wheel cylinders (Wfr, Wfl), and are divided into two pipes (MF, MF1, MF2)
A second electromagnetic on-off valve (SREC) is provided for generating a braking force on the regulator and the third and fourth wheels (RR, RL) as rear wheels via the second electromagnetic on-off valve. Are connected to the third and fourth wheel cylinders (Wrr, Wrl), and are branched into two on the third and fourth wheel cylinder side from the second electromagnetic on-off valve (MR, MR1, MR2)
A third electromagnetic on-off valve (STR) is provided, and is accumulated in the accumulator between the second electromagnetic on-off valve and the third and fourth wheel cylinders in the second pipe through the third electromagnetic on-off valve. A third pipe (AM) for guiding the brake fluid pressure;
A fourth electromagnetic on-off valve (SREA), through the fourth electromagnetic on-off valve, between the first electromagnetic on-off valve and the first and second wheel cylinders in the first pipe line, and the second pipe line; A fourth pipe (AC) for connecting the second electromagnetic on-off valve and the third and fourth wheel cylinders in
Control for setting the flow path of the brake fluid by driving the fluid pressure pump and controlling the fluid pressure of the accumulator to be within a predetermined range and controlling the first to fourth electromagnetic on-off valves. Means (10),
The control means includes
Brake assist control in which the hydraulic pressure of the accumulator (Acc) exceeding the brake hydraulic pressure corresponding to the operation amount of the brake operating member (BP) is applied to any of the first to fourth wheel cylinders (Wfr to Wrl). Means (110) for determining whether or not a start condition is satisfied;
When the brake assist control start condition is satisfied, the first and second electromagnetic on / off valves are shut off and the third and fourth electromagnetic on / off valves are in communication to execute the brake assist control. Means for instructing (130);
Means (140) for determining whether or not an end condition of the brake assist control is satisfied;
When the termination condition is satisfied, as the brake assist control termination processing, the third electromagnetic on-off valve is turned off, the second electromagnetic on-off valve is brought into communication, and the second electromagnetic on-off valve is opened. A vehicle brake control device comprising: means for instructing the first electromagnetic on-off valve to be in a communication state with a predetermined delay time delayed from a timing at which the valve is in a communication state.   Means for setting the delay time when the first electromagnetic on-off valve is in the communication state delayed by a predetermined time from the timing at which the second electromagnetic on-off valve is in the communication state to be smaller as the return speed of the brake operation member is larger. The vehicle brake control device according to claim 7, comprising:

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