JP4235158B2 - Brake control device for vehicle - Google Patents

Description

  The present invention relates to a vehicle brake control device having a function (hill start assist function) for assisting a brake operation when stopping on a hill and starting a hill by controlling a braking force applied to a wheel.

  In recent years, by controlling the brake fluid pressure applied to the wheels (hereinafter also referred to as “caliper pressure”), the function of suppressing unintended forward / backward movement (hereinafter also referred to as “sliding down”) when starting a slope, There is a vehicle brake control device having a so-called hill start assist function. As such a device, conventionally, it is determined that the vehicle has stopped when a state where the braking force of the brake is equal to or higher than a preset value continues for a predetermined time, and the braking force at that time (specifically, caliper pressure) By maintaining the value and setting the target value for brake control while the vehicle is stopped, if the caliper pressure falls below the target value for any reason even before starting, the caliper pressure is increased so that the vehicle does not slide down. A vehicle brake control device that performs control is known (see Patent Document 1).

JP-A-11-334550

  By the way, in the vehicle brake control device, when the caliper pressure falls below the target value, it is necessary to increase the caliper pressure by pressurizing with a hydraulic pump. In order to reach the caliper pressure, it is necessary to drive the hydraulic pump at a high speed or for a long time, which causes problems such as noise problems and deterioration of the brake operation feeling by the driver.

  On the other hand, the amount of depression of the brake pedal when stopping is largely due to the individuality of the driver. Therefore, the method of setting the braking force (caliper pressure) when it is determined that the vehicle has stopped as described above is a gentle slope. However, a caliper pressure higher than necessary may be set as a target value, and in this case, the above-described problem tends to occur.

  Further, in the above-described technology, when it is determined that the vehicle has stopped, holding control (control for closing the electromagnetic valve and confining the brake fluid pressure on the wheel brake side) is performed, and thereafter the feeling of brake operation is deteriorated. There was also a problem (for example, the driver feels a so-called wall feeling that the brake pedal does not move even if the pedal is stepped on).

  Therefore, an object of the present invention is to provide a vehicle brake control device that can prevent the braking force from being unnecessarily held or increased when the vehicle stops on a gentle slope.

The invention according to claim 1 of the present invention that solves the above-mentioned problems is a stop determination unit that determines whether or not the vehicle has stopped based on the vehicle state quantity, and a brake fluid that is used for braking force control after the stop determination. a control parameter reference condition setting means for setting a first threshold value and second threshold value is a standard condition of pressure value, after the vehicle stop determination, the standard condition in which the brake fluid pressure is set by the control parameter reference condition setting means the if not satisfied, a vehicle brake control system and a braking force control means for performing control of the system Ru is retained or increased regardless braking force of the presence or absence of the driver braking operation, the control parameter reference condition setting means, among the brake fluid pressure value that varies between the said stop determination means is performing a stop determination, setting the first threshold value based on the values of the minimum In addition, a value lower than the first threshold value by a predetermined amount is set as the second threshold value, and the braking force control means has a brake fluid pressure value after stoppage determination that is less than the first threshold value and less than the second threshold value. If the brake fluid pressure value after stopping is determined to be less than or equal to the second threshold value, the braking force is increased .

Here, the “vehicle state quantity” refers to a parameter necessary for determining whether or not the vehicle has stopped. For example, the wheel speed detected by the wheel speed sensor or the vehicle longitudinal direction detected by the longitudinal acceleration sensor. This corresponds to the fluctuation range of acceleration, the master cylinder pressure and caliper pressure of the brake, the throttle opening, the brake depression force, and the brake ON / OFF. Further, “after stoppage determination” refers to after the stoppage determination means determines that the vehicle has stopped. In addition, the "control parameters", will have a parameter to be controlled at the time of performing the braking force control (parameters related to the braking force). The control parameter of the present invention is the brake fluid pressure in the case of a hydraulic brake.

According to the first aspect of the invention, when stopping the vehicle, first, the stop determination means determines whether or not the vehicle state quantity satisfies the predetermined stop condition for a predetermined determination time. Then, it is determined whether or not the vehicle has stopped. Then, after it is determined that the vehicle has stopped, the control parameter reference condition setting means sets the reference condition based on the value of the control parameter that fluctuates during the stop determination based on the value at which the braking force is minimized. Based on the reference conditions set as described above, the braking force control means performs control so as to hold or increase the braking force applied to the vehicle. That is, the braking force control means controls the holding or increasing of the braking force under the reference condition set based on the minimum braking force necessary for stopping the vehicle, so that the vehicle stops on a gentle slope. In this case, for example, in the case of a hydraulic brake, it is possible to prevent noise caused by driving of the hydraulic pump and deterioration in feeling of brake operation.
Further, in the hydraulic brake, the braking force can be controlled more accurately by using the brake hydraulic pressure value directly indicating the braking force as a control parameter.

  The invention according to claim 2 is the vehicle brake control device according to claim 1, wherein a signal from a gradient detection means for detecting the gradient of the stop position of the vehicle is input, wherein the control parameter reference condition setting means is provided. Includes reference condition correction means for correcting the reference condition so that the influence of the gradient on braking is suppressed based on the gradient detected by the gradient detection means, and the braking force control means includes the reference force The braking force is held or increased based on the corrected reference condition corrected by the condition correcting means.

  According to the second aspect of the present invention, as described above, when stopping the vehicle, first, the determination by the stop determination unit is performed, and after it is determined that the vehicle has stopped, the control parameter reference condition setting unit is determined. However, the reference condition is set based on the value of the control parameter that fluctuates during the stop determination and the value at which the braking force is minimized. The reference condition set in this way is further corrected by the reference condition correction means so that the influence on the braking due to the gradient of the stop position of the vehicle is suppressed. For this reason, for example, when the brake is depressed in anticipation of a stoppage due to inertia on an uphill (the minimum braking force during stoppage determination is less than the minimum braking force required to maintain the vehicle stopped) It is possible to prevent the vehicle from sliding down when it becomes smaller.

  A third aspect of the present invention is the vehicle brake control device according to the second aspect, wherein the reference condition correction unit is configured to detect a current reference condition as the gradient detected by the gradient detection unit increases. Is largely corrected.

  According to the third aspect of the present invention, the correction amount of the reference condition is increased according to the gradient of the stop position of the vehicle. Therefore, the braking force is increased by increasing the braking force on a steep slope and making sure the braking force. The vehicle can be stopped at a low speed, and on a gentle slope slope, the increase of the braking force is suppressed to a small braking force, so that the vehicle can be stopped reliably and useless energy (for example, driving energy of the hydraulic pump). ) Can also be reduced.

  According to a fourth aspect of the present invention, there is provided the vehicle brake control device according to any one of the first to third aspects, wherein a signal from a longitudinal motion detection means for detecting the longitudinal motion of the vehicle is input. The control parameter reference condition setting means includes forward / backward correction means for correcting the reference condition so that a braking force is increased based on a signal from the forward / backward movement detection means after the stoppage determination. And

  According to the fourth aspect of the present invention, when the longitudinal motion detection means detects the longitudinal motion of the vehicle and outputs the signal to the longitudinal motion correction means after the stoppage determination, the longitudinal motion correction means Based on this, the reference condition is corrected so that the braking force increases. That is, the forward / backward movement correction means corrects the reference condition based on the signal from the forward / backward movement detection means that directly detects that the vehicle cannot be stopped. Can be reliably prevented.

  The invention according to claim 5 is the vehicle brake control device according to claim 4, wherein the longitudinal movement detecting means is a wheel speed sensor that emits one pulse each time the wheel rotates by a predetermined angle. And the forward / backward correction means gradually increases the braking force by correcting the reference condition by a predetermined amount every time a predetermined number of pulses are input from the wheel speed sensor after the stoppage determination. It is characterized by.

  According to the fifth aspect of the present invention, when a predetermined number (for example, one) of pulses is input from the wheel speed sensor, the forward / backward movement correcting means corrects the reference condition by a predetermined amount each time and applies a braking force. Gradually increase. Therefore, as the amount of vehicle sliding down increases, the braking force increases, so that a braking force commensurate with the vehicle sliding down can be obtained, and the vehicle can be stopped with the minimum necessary braking force. Can do.

According to the first aspect of the present invention, the braking force control means controls holding or increasing the braking force under the reference condition set based on the minimum braking force necessary for stopping the vehicle. Therefore, it is possible to prevent the braking force from being held or increased unnecessarily when the vehicle stops on a gentle slope. According to the first aspect of the present invention, in the hydraulic brake, the braking force can be controlled more accurately by using the brake hydraulic pressure value directly indicating the braking force as a control parameter.

  According to the second aspect of the present invention, the reference condition is corrected by the reference condition correcting means so that the influence on the braking by the gradient of the stop position of the vehicle is suppressed. It is possible to prevent the vehicle from sliding down when the power is smaller than the minimum braking force required to maintain the vehicle stopped.

  According to the third aspect of the invention, since the correction amount of the reference condition is increased according to the gradient of the stop position of the vehicle, an appropriate braking force according to the gradient can be obtained.

  According to the fourth aspect of the present invention, the reference condition is determined based on the signal from the longitudinal motion detecting means that directly detects that the longitudinal motion correcting means cannot maintain the vehicle stop state. Since it correct | amends, the sliding down of a vehicle can be prevented reliably.

  According to the fifth aspect of the present invention, the forward / backward correction means corrects the reference condition by a predetermined amount and gradually increases the braking force each time a pulse is input from the wheel speed sensor. The braking force commensurate with the sliding down can be obtained.

[First Embodiment]
Next, a first embodiment of a vehicle brake control device according to the present invention will be described in detail with reference to the drawings as appropriate.

  As shown in FIG. 1, the vehicle brake control device A is for appropriately controlling the braking force (brake hydraulic pressure) applied to each wheel T of the vehicle CR, and is provided with an oil passage and various parts. It mainly includes a pump body 10 and a control device 20 for appropriately controlling various components in the pump body 10. The control device 20 of the vehicle brake control device A includes a wheel speed sensor 30 for detecting the wheel speed of each wheel T of the vehicle CR, and a front and rear for detecting acceleration applied in the front-rear direction of the vehicle CR. The acceleration sensor 40, the pressure sensor 50 for detecting the pressure in the wheel cylinder H provided on each wheel T, the brake lamp switch 70 for detecting whether or not the brake pedal P is operated, and the liquid in the master cylinder M A master cylinder hydraulic pressure sensor 80 for detecting pressure is connected. Here, the control device 20 includes, for example, a CPU, a RAM, a ROM, and an input / output circuit, and inputs from the wheel speed sensor 30, the longitudinal acceleration sensor 40, the pressure sensor 50 and the brake lamp switch 70, and is stored in the ROM. The control is executed by performing various arithmetic processes based on the programmed program and data. Further, the wheel cylinder H is for applying brake fluid pressure to the wheel brakes FL, RL, FR, RR provided on each wheel T, and the pump body of the vehicle brake control device A is respectively connected via a pipe. 10 is connected. In the present embodiment, the magnitude of the brake fluid pressure supplied to the wheel cylinder H (corresponding to a caliper pressure described later), that is, the brake fluid pressure value is a control parameter.

  Next, functions of various components provided in the pump body 10 will be briefly described with reference to the brake hydraulic circuit diagram of FIG. In FIG. 2, a solid line connecting various components in the pump body 10 indicates an oil passage formed in the pump body 10.

  The pump body 10 is disposed between a master cylinder M that generates a brake fluid pressure corresponding to the pedaling force applied by the driver to the brake pedal P and the wheel brakes FL, RR, RL, FR. The two output ports M1, M2 of the master cylinder M are connected to the inlet port 121 of the pump body 10, and the outlet port 122 of the pump body 10 is connected to each wheel brake FL, RR, RL, FR. In normal times, the oil passage is communicated from the inlet port 121 to the outlet port 122 in the pump body 10 so that the depression force of the brake pedal P is transmitted to each wheel brake FL, RR, RL, FR. It is like that.

  Here, the oil path starting from the output port M1 leads to the wheel brake FL on the left side of the front wheel and the wheel brake RR on the right side of the rear wheel, and the oil path starting from the output port M2 is set to the wheel brake FR on the right side of the front wheel and the left side of the rear wheel. To the wheel brake RL. Hereinafter, the oil passage starting from the output port M1 is referred to as “first system”, and the oil passage starting from the output port M2 is referred to as “second system”.

  The pump body 10 is provided with two control valve means V corresponding to each wheel brake FL, RR in the first system, and similarly, corresponding to each wheel brake RL, FR in the second system. Two control valve means V are provided. The pump body 10 is provided with a reservoir 3, a pump 4, a damper 5, an orifice 5a, a regulator R, a suction valve 7, and a storage chamber 7a in each of the first system and the second system. A common electric motor 60 for driving the first system pump 4 and the second system pump 4 is provided. In the present embodiment, the master cylinder hydraulic pressure sensor 80 is provided only in the second system (outside the pump body 10). In this embodiment, the master cylinder hydraulic pressure sensor 80 is provided outside the pump body 10, but the present invention is not limited to this, and the pump cylinder 10 is provided with the master cylinder hydraulic pressure sensor 80. Also good.

  In the following, the oil passage from the output ports M1, M2 of the master cylinder M to each regulator R is referred to as “output hydraulic pressure passage A”, and the oil passage from the first system regulator R to the wheel brakes FL, RR and The oil passages from the second system regulator R to the wheel brakes RL and FR are respectively referred to as “wheel hydraulic pressure passage B”. In addition, an oil path from the output hydraulic pressure path A to the pump 4 is referred to as “suction hydraulic pressure path C”, an oil path from the pump 4 to the wheel hydraulic pressure path B is referred to as “discharge hydraulic pressure path D”, and The oil path from the wheel hydraulic pressure path B to the suction hydraulic pressure path C is referred to as “release path E”.

  The control valve means V opens the wheel hydraulic pressure path B while blocking the release path E, blocks the wheel hydraulic pressure path B while opening the release path E, and blocks the wheel hydraulic pressure path B and releases it. It has a function of switching the state of shutting off the path E, and includes an inlet valve 1, an outlet valve 2, and a check valve 1a.

  The inlet valve 1 is a normally open electromagnetic valve provided in the wheel hydraulic pressure path B. The inlet valve 1 is normally open to allow the brake hydraulic pressure to be transmitted from the master cylinder M to the wheel brakes FL, RR, RL, FR. Further, the inlet valve 1 is blocked by the control of the control device 20 when the wheel is about to be locked, so that the brake hydraulic pressure transmitted from the brake pedal P to each wheel brake FL, RR, RL, FR is cut off. To do.

  The outlet valve 2 is a normally closed electromagnetic valve interposed between the wheel hydraulic pressure path B and the release path E. Although the outlet valve 2 is normally closed, the brake fluid pressure acting on each wheel brake FL, RR, RL, FR is opened by the control of the control device 20 when the wheel is likely to be locked. To each reservoir 3. For example, in the case of anti-lock control, the pressure on the wheel cylinder H side (hereinafter also referred to as “caliper pressure”) is maintained by closing both the outlet valve 2 and the inlet valve 1.

  The check valve 1a is connected to each inlet valve 1 in parallel. This check valve 1a is a valve that allows only the flow of brake fluid from the wheel brakes FL, RR, RL, FR side to the master cylinder M side. When the input from the brake pedal P is released, the check valve 1a Even when the valve 1 is closed, the brake fluid is allowed to flow from the wheel brakes FL, RR, RL, FR side to the master cylinder M side.

  The reservoir 3 is provided in the release path E, and has a function of absorbing brake fluid pressure that is released when each outlet valve 2 is opened. Further, between the reservoir 3 and the pump 4, a check valve 3a that allows only the inflow of brake fluid from the reservoir 3 side to the pump 4 side is interposed.

  The pump 4 is interposed between the suction hydraulic pressure path C leading to the output hydraulic pressure path A and the discharge hydraulic pressure path D leading to the wheel hydraulic pressure path B, and sucks the brake fluid stored in the reservoir 3. And has a function of discharging to the discharge hydraulic pressure path D. As a result, the pressure state of the output hydraulic pressure path A and the wheel hydraulic pressure path B reduced by the absorption of the brake hydraulic pressure by the reservoir 3 is recovered. Further, in this pump 4, a cut valve 6 which will be described later blocks inflow of brake fluid from the output hydraulic pressure path A to the wheel hydraulic pressure path B, and a suction valve 7 which will be described later opens the suction hydraulic pressure path C. The brake fluid stored in the master cylinder M, the output hydraulic pressure path A, the suction hydraulic pressure path C, and the storage chamber 7a is sucked and discharged to the discharge hydraulic pressure path D. This makes it possible to apply brake fluid pressure to each wheel brake FL, RR, RL, FR during non-pedal operation.

  The damper 5 and the orifice 5a attenuate the pulsation of the pressure of the brake fluid discharged from the pump 4 and the pulsation generated by the operation of the regulator R described later by the cooperative action.

  The regulator R has a function of switching between a state where the brake fluid is allowed to flow from the output hydraulic pressure passage A to the wheel hydraulic pressure passage B and a state where the brake fluid is blocked, and a brake fluid flow from the output hydraulic pressure passage A to the wheel hydraulic pressure passage B. It has a function of adjusting the brake fluid pressure in the wheel fluid pressure passage B and the discharge fluid pressure passage D to a set value or less when the inflow is cut off, and the cut valve 6, the check valve 6a and the relief valve 6b are provided. It is prepared for.

  The cut valve 6 is a normally-open electromagnetic valve interposed between the output hydraulic pressure path A leading to the master cylinder M and the wheel hydraulic pressure path B leading to each wheel brake FL, RR, RL, FR. The state in which the inflow of the brake fluid from the output hydraulic pressure path A to the wheel hydraulic pressure path B is permitted and the state in which the brake fluid is blocked are switched. The cut valve 6 is normally open, thereby allowing the brake hydraulic pressure to be transmitted from the master cylinder M to the wheel brakes FL, RR, RL, FR. Further, the cut valve 6 is a control device when the pump 4 is operated when the pedal is not operated, in other words, when the brake fluid pressure is applied to the wheel brakes FL, RR, RL, and FR when the pedal is not operated. Blocked by 20 control. The cut valve 6 is realized by a linear solenoid valve capable of adjusting the valve opening pressure by controlling energization to the solenoid, for example. When a linear solenoid valve is employed as the cut valve 6 in this manner, the hydraulic pressure applied from the wheel hydraulic pressure path B to the cut valve 6 and the force for closing the valve controlled by energizing the solenoid of the cut valve 6 is closed. Therefore, the hydraulic pressure of the wheel hydraulic pressure passage B can be adjusted to be appropriately opened to the output hydraulic pressure passage A.

  The check valve 6a is connected to each cut valve 6 in parallel. The check valve 6a is a valve that only allows the brake fluid to flow from the output hydraulic pressure path A to the wheel hydraulic pressure path B. When the cut valves 6 are closed, the check valve 6a receives an input from the brake pedal P. Even if it exists, inflow of the brake fluid from the output hydraulic pressure path A to the wheel hydraulic pressure path B is permitted.

  The relief valve 6b is connected in parallel to each cut valve 6, and opens when the brake fluid pressure in the wheel fluid pressure passage B and the discharge fluid pressure passage D becomes equal to or higher than a set value.

  The suction valve 7 is a normally closed electromagnetic valve provided in the suction fluid pressure passage C, and switches between a state in which the suction fluid pressure passage C is opened and a state in which the suction fluid pressure passage C is shut off. The suction valve 7 is in a non-pedal operation, and when the cut valve 6 is in a state of blocking the inflow of brake fluid from the output hydraulic pressure path A to the wheel hydraulic pressure path B, in other words, in the non-pedal operation. When the brake fluid pressure is applied to the wheel brakes FL, RR, RL, FR, it is opened (opened) by the control of the control device 20.

  The storage chamber 7 a is the suction fluid pressure path C and is provided between the pump 4 and the suction valve 7. The storage chamber 7a stores brake fluid, and the capacity of the brake fluid stored in the suction fluid pressure path C is thereby substantially increased.

  The master cylinder hydraulic pressure sensor 80 measures the brake hydraulic pressure in the output hydraulic pressure path A, and the measurement result is taken into the control of the control device 20 as needed.

Next, with reference to a main part block diagram according to the present invention shown in FIG. 3, functions of main parts according to the present invention of the control device 20 will be described in detail.
The control device 20 includes a stop determination unit 21, a caliper pressure threshold setting unit (control parameter reference condition setting unit) 22, and a braking force control unit 23.

  The stop determination means 21 has a stop determination function for determining whether the vehicle CR has stopped based on the vehicle state quantity. Specifically, the stop determination means 21 is configured such that <1> the brake lamp switch 70 is ON, that is, the brake pedal P is operated, and <2> the signal output from the wheel speed sensor 30 is “wheel speed = 0. , And <3> the longitudinal acceleration detected by the longitudinal acceleration sensor 40 is “within a predetermined range close to the acceleration fluctuation range = 0”, and the determination of the continuation of the stopped state is started. . The stop determination means 21 determines that the vehicle CR has stopped (stopped) when the aforementioned stop conditions (<1> to <3>) have continued for a predetermined time. Here, the state in which the signal output from the wheel speed sensor 30 is a signal indicating “wheel speed = 0” means that, for example, one wheel speed pulse generated every time the wheel rotates by a predetermined angle is a predetermined time. A state where no input is received. The stop determination means 21 outputs a stop determination start signal to the caliper pressure threshold setting means 22 when starting the determination of continuation of the stop state, and outputs a stop determination completion signal when determining that the vehicle has stopped. It is output to the setting means 22 and the braking force control means 23 (or a flag indicating that the vehicle is stopped may be set).

  The caliper pressure threshold value setting unit 22 performs braking force control after the stop determination based on the stop determination start signal and the stop determination completion signal output from the stop determination unit 21 and the signal output from the pressure sensor 50. It has a function of setting a threshold value (reference condition) for the caliper pressure to be provided. Specifically, the caliper pressure threshold setting means 22 includes a caliper pressure value (see FIG. 5) that fluctuates from when the stop determination start signal is received from the stop determination means 21 until when the stop determination completion signal is received. A minimum value is set as the first threshold, and a value that is lower than the first threshold by a predetermined amount is set as the second threshold. The setting of these threshold values will be described in detail in a control flow (see FIG. 4) described later. Further, in the present embodiment, the minimum caliper pressure is used as the first threshold value as it is, but the present invention is not limited to this, and for example, a known filter process for removing noise to a caliper pressure value that is appropriately minimized is executed. Then, the processed value may be set as the first threshold value.

  When the caliper pressure falls below the first threshold value and the second threshold value after the stop determination by the stop determination unit 21 (after determining that the vehicle has stopped), the braking force control unit 23 determines whether or not the driver has operated the brake. Regardless, it has a function of executing control to maintain the stopped state by increasing the braking force. Specifically, when the braking force control means 23 receives the stop completion signal from the stop determination means 21, the caliper pressure threshold value setting means 22 outputs the caliper pressure first threshold value and the second threshold value, and the pressure sensor 50. When the measured caliper pressure is within the range from the first threshold value to the second threshold value, the cut valve 6 is closed (the inlet valve at this time). 1 is open, the outlet valve 2 and the suction valve 7 are closed). When the caliper pressure is maintained and the measured caliper pressure is less than or equal to the second threshold value, the suction valve 7 is opened, The caliper pressure is increased by driving the hydraulic pump 4 with the cut valve 6 closed.

  And the control apparatus 20 provided with each above-mentioned means 21,22,23 is operate | moving based on the control flow as shown in FIG. Below, operation | movement of the control apparatus 20 controlled by this control flow is demonstrated.

  First, the control device 20 determines whether or not the brake lamp switch 70 is in the ON state by the stop determination means 21 (step S1). If it is determined that the brake lamp switch 70 is in the ON state (Yes), normal brake control is performed. (Step S2), and when it is determined that the state is OFF (No), this control flow is terminated. Then, after step S2, whether or not the aforementioned stopping conditions “<2> wheel speed = 0” and “<3> longitudinal acceleration is within a predetermined range close to acceleration fluctuation range = 0” are determined. Determination is made (step S3). Note that the stopping condition in step S3 is not limited to the above-described condition. For example, in addition to the above-described condition, “the brake lamp switch 70 is ON”, “the master cylinder pressure is a predetermined value or more”, A condition such as “the throttle or accelerator opening must be a predetermined value or less” may be added.

  If it is determined in step S3 that the vehicle stop condition is satisfied (Yes), the caliper pressure detected by the pressure sensor 50 at that time is stored as the current value (step S4). In this step S4, the caliper pressure is detected. However, the present invention is not limited to this. For example, the current value of the caliper pressure may be estimated by a conventionally known method.

  After step S4, it is determined whether or not the caliper pressure detected this time is lower than the caliper pressure detected last time (step S5). If it is determined in step S5 that the current caliper pressure is lower than the previous caliper pressure (Yes), the current caliper pressure is changed to the first threshold (step S6). In step S6, the second threshold is changed (a process of subtracting a predetermined value from the first threshold) in conjunction with the change of the first threshold.

  Then, after step S6 or after determining No in step S5, the process proceeds to step S7, where it is determined whether or not the stop state has continued for a predetermined time. If it is determined in step S7 that the vehicle has continued (Yes), it is determined that the vehicle CR has stopped. That is, the control device 20 functions as a stop determination unit by the processing of steps S1 to S7, and functions as a control parameter reference condition setting unit by the processing of steps S4 to S6. Next, it is determined whether or not the current caliper pressure is lower than the first threshold value and higher than the second threshold value that is smaller than the first threshold value (step S8). It is determined whether or not it is slightly below the first threshold value. If it is determined No in step S7 or if it is determined No in step S3, the process returns to step S1.

  If it is determined in step S8 that Yes (for example, it is slightly lower than the detection fluctuation or noise of the pressure sensor 50 is allowed), the cut valve 6 is closed by the braking force control means 23 and the caliper is closed. Pressure holding control is started (step S9). Further, when it is determined No (outside the range from the first threshold value to the second threshold value) in step S8, it is determined whether or not the current caliper pressure is equal to or lower than the second threshold value (step S10). ), Whether or not the current caliper pressure is significantly below the first threshold value is determined.

  If it is determined in step S10 that Yes (significantly lower), pressurization control by the hydraulic pump 4 is performed (step S11). After this step S11 or when it is determined No in step S10 (current caliper pressure is greater than or equal to the first threshold value), it is determined whether or not the brake lamp switch 70 is OFF (step S12). If it is determined in step S12 that the brake lamp switch 70 is still ON (No), the caliper pressure is detected (step S15), and the process returns to step S8 again. That is, the processes in steps S8 to S12 are repeated until the brake lamp switch 70 is turned off. In such a process (steps S8 to S12), if the current caliper pressure is equal to or higher than the first threshold when the process first proceeds from step S7 to step S8, until the current caliper pressure falls below the first threshold, By repeating the process of step S8: No, step S10: No, and step S12: No, holding control or pressurization control will not be performed. Therefore, until the holding control or pressurization control is performed (until the current caliper pressure falls below the first threshold value), the driver does not feel uncomfortable with the operation of the brake pedal P, and the hydraulic pressure Noise due to driving of the pump 4 can also be prevented. It should be noted that during the process of steps S8 to S12, once the current caliper pressure detected in step S15 falls below the first threshold value, the caliper pressure detected in step S15 thereafter becomes the step S8 or step S15. Until the condition of S10 is satisfied, either one of the holding control and the pressurizing control is performed. In steps S8 to S12, S15, when the brake pedal P is "added", the increased hydraulic pressure is supplied to the wheel brakes FL, RR, RL, FR via the check valve 6a. The

  If it is determined in step S12 that the brake lamp switch 70 has been turned off (Yes), the holding control or pressurization control being executed is stopped (step S13), and the control is gradually shifted to the removal control (step S13). Step S14). Here, “gradual release control” is control that is performed when the driver releases the brake pedal P in order to move to the start operation, so that the control target value of the cut valve 6 can be easily opened over time. This refers to control in which the caliper pressure is gradually released over a predetermined time by appropriately controlling.

  Then, when the gradual removal control in step S14 is finished (when the caliper pressure becomes 0), this control flow is finished. In addition, even if this control flow is once complete | finished, it returns to a start again, and, thereby, each above-mentioned step S1-S15 is performed repeatedly.

Next, an example of the operation of the vehicle brake control device A according to the present embodiment will be described with reference to the time chart shown in FIG.
As shown in FIG. 5A, when the driver depresses the brake pedal to stop the vehicle CR on the slope, the brake lamp switch (BLS) 70 is turned on (time T1), and the caliper pressure is reduced to the brake pedal. It rises according to the stepping force. Then, due to the increase in the caliper pressure, the fluctuation range of the wheel speed and acceleration converges toward 0, and when the vehicle stop condition is satisfied, the stop state continuation determination is started (time T2).

  Then, if the state where the stop condition is satisfied is continued for a predetermined time (from time T3 to time T2) from the start of the stop state continuation determination, it is determined that the vehicle CR has stopped, and the stop determination completion signal is It is output to the caliper threshold value setting means 22 and the braking force control means 23 (time T3). In addition, the minimum value of the caliper pressure during the continuation determination of the stationary state is performed by appropriately changing the first threshold as described above during the continuation determination of the stationary state (steps S1 to S7, particularly step S6 described above). Is set as the first threshold value.

  After the stop determination is confirmed (that is, after the stop determination), the driver maintains the brake pedal depression amount to maintain the vehicle CR, but if the driver suddenly loosens the brake pedal depression The caliper pressure drops sharply as shown by the two-dot chain line in the figure, and if it falls below the first threshold value, the second threshold value also falls below in a very short time (see FIG. 5B). ), Without performing the holding control, the hydraulic pressure pump 4 is driven, the inlet valve 1 and the suction valve 7 are opened, and the outlet valve 2 and the cut valve 6 are closed (time T4). ). This operation corresponds to the determination of No in step S8 described above, the determination of Yes in step S10, and the process proceeding to step S11.

  Then, after the caliper pressure is recovered by the pressurization control, the driving of the hydraulic pump 4 is stopped (time T5), and the inlet valve 1 and the suction valve 7 are closed to hold the braking force. (Time T5 to T6). Thereafter, when the driver removes his / her foot from the brake pedal to enter the start operation, the brake lamp switch 70 is turned off (time T6), and the holding control (or pressurization control) being executed is interrupted.

After that, by gradually controlling the removal at a predetermined flow rate (time T6 to T7), the caliper pressure becomes 0 after a predetermined time, and normal traveling is performed. In addition, the following effects can be acquired by performing this removal control gradually.
(1) When the operation is switched from the brake to the accelerator, it is possible to prevent the deterioration of the feeling of sudden acceleration at the moment of pressure reduction by preventing the hydraulic pressure from suddenly dropping.
(2) When accelerator control is difficult, such as starting on a low friction road surface or starting uphill, it can be controlled to start (accelerate) gradually even if the accelerator is opened roughly.
(3) Even if the brake is released and the accelerator is not turned on, the vehicle can be gradually moved without sudden advance / retreat for safety.
In FIG. 5, the first threshold value is gradually returned to the initial value (zero) at the time when the first threshold control is finished, but the present invention is not limited to this, and immediately after the first control is started. Alternatively, the first threshold value may be returned to the initial value, or the first threshold value may not be returned to the initial value but may be left as it is after the control is finished.

According to the above, the following effects can be obtained in the first embodiment.
Since the braking force control means 23 determines the first threshold value and the second threshold value based on the minimum caliper pressure necessary for stopping the vehicle CR, and controls the holding or increasing of the caliper pressure, it is possible to make a gentle slope. It is possible to prevent the caliper pressure from being held or increased unnecessarily when the vehicle stops.

  Since the caliper pressure is not held or pressurized for a predetermined time after the stop determination is confirmed, it is possible to suppress deterioration in the feeling of brake operation.

[Second Embodiment]
Next, a third embodiment of the vehicle brake control device according to the present invention will be described. Since this embodiment is obtained by changing a part of the control device 20 according to the first embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 6, the control device 20 ′ corresponds to the control device 20 of the first embodiment, and includes a stop determination means 21 and a braking force control means 23 having the same functions as those of the first embodiment. The caliper pressure threshold value setting means 22 ′ to which a new function is added as compared with the first embodiment and the gradient calculating means 24 as a new component are mainly configured.

  The gradient calculation unit 24 has a function of calculating the gradient of the stop position of the vehicle CR based on a signal output from the longitudinal acceleration sensor (gradient detection unit) 40. Specifically, the gradient calculating unit 24 calculates the gradient (estimated slope) of the stop position of the vehicle CR based on the acceleration in the vehicle longitudinal direction detected by the longitudinal acceleration sensor 40 and the gravitational acceleration, and the caliper pressure The data is output to the threshold setting means 22 ′.

  The caliper pressure threshold value setting means 22 ′ has the same function as the caliper pressure threshold value setting means 22 according to the first embodiment (function for setting the first threshold value and the second threshold value based on the minimum caliper pressure during stoppage determination). In addition to the above, based on the gradient calculated by the gradient calculation means 24, there is a function (reference condition correction means) for correcting the first threshold value and the second threshold value of the caliper pressure so that the influence of the gradient on braking is suppressed. is doing. Specifically, when the caliper pressure threshold setting means 22 ′ receives a stop determination completion signal from the stop determination means 21, the gradient (estimated inclination) output from the gradient calculation means 24 at that time and the map shown in FIG. Based on the above, a correction pressure is derived. Information about the map is stored in advance in a non-volatile storage medium such as a ROM mounted on the control device 20 ′, for example.

  That is, for example, if the gradient calculated by the gradient calculation means 24 is calculated based on the acceleration in the forward direction (for example, a positive value), the caliper pressure threshold value setting means 22 ′ is indicated by a broken line on the map. If the correction pressure is derived by referring to the descent constant and the gradient is calculated based on the backward acceleration (for example, a negative value), the caliper pressure threshold value setting means 22 ′ is indicated by a solid line on the map. The correction pressure is derived with reference to the climbing constant shown. Incidentally, the correction pressure of this map is set so that the larger the gradient is, the larger the value is, and at the same gradient, the upward correction pressure is larger than the downward correction pressure. . After deriving the correction pressure in this way, the caliper pressure threshold value setting means 22 ′ adds this correction pressure to the first threshold value (threshold value set to the minimum value) and the second threshold value of the caliper pressure. Thus, these threshold values are corrected.

  Next, the operation of the control device 20 'according to the present embodiment will be described based on the control flow shown in FIG. In addition, since the control flow of this embodiment adds new step S20 between step S7 and step S8 in the control flow (refer FIG. 4) shown in 1st Embodiment, this new step S20. Only the explanation will be given, and the explanation of the other steps S1 to S15 will be omitted.

  In step S20, the first threshold value and the second threshold value set based on the minimum caliper pressure during the continuation determination of the stop state by being appropriately changed in steps S1 to S7 are values in consideration of the stop position gradient of the vehicle CR. It has been corrected to. Specifically, the processing in step S20 is a subroutine as shown in FIG. That is, when it is determined in step S7 that the stationary state has continued for a predetermined time (Yes), the caliper pressure threshold value setting means 22 'shows a signal indicating the gradient sent from the gradient calculation means 24 at that time and the figure. The correction pressure is calculated by referring to the map 7 (step S21). After step S21, the correction pressure is added to the first threshold value and the second threshold value (step S22), the control flow returns to FIG. 8 (RETURN), and the process proceeds to the next step S8. .

  Next, an example of the operation of the vehicle brake control device A according to the present embodiment will be described with reference to the time charts shown in FIGS. In the following, since the operation from time T1 to T3 is the same as that of the first embodiment, the description thereof is omitted, and the wheel speed and acceleration fluctuation range shown in FIG. The threshold is also omitted.

First, with reference to FIG. 10A, a case where the vehicle CR is stopped on a slope having a gentle slope will be described.
When it is determined that the vehicle CR is in a stopped state at time T3 (when it is determined that the vehicle has stopped), first, the first threshold value and the second threshold value are determined based on the minimum value of the caliper pressure during the stop state continuation determination. Is set, a first pressure and a second threshold (not shown) that are somewhat lower are determined by adding a correction pressure α corresponding to the gentleness to these thresholds. Then, the caliper pressure corresponding to the depression force of the brake pedal is usually higher than the first threshold value, so that holding control and pressurization are performed for a predetermined time (time T9-time T3) after the stop determination is confirmed. Since the control is not performed, the driver can maintain the depression of the brake pedal without feeling the deterioration of the feeling of brake operation. The operation at this time corresponds to the determination of Yes in step S7 described above, the process proceeds to step S20, and the processing in steps S21 and S22 is performed.

  Then, when the caliper pressure slightly falls below the first threshold due to the driver slowly depressing the brake pedal, the caliper pressure holding control is performed (time T9). This operation corresponds to the determination of Yes in step S8 described above and the process proceeding to step S9. Thereafter, when the driver removes his / her foot from the brake pedal so as to start the start operation, the brake lamp switch 70 is turned off (time T8), the holding control being executed is interrupted, and the release control is gradually performed. Will be.

Next, a case where the vehicle CR is stopped on a slope having a steep slope will be described with reference to FIG.
When it is determined that the vehicle CR is in a stopped state (time T3), first, the first threshold value and the second threshold value are set based on the minimum value of the caliper pressure during the stop state continuation determination. Is added with a correction pressure β (a value larger than the correction pressure α) corresponding to the steep inclination, thereby a first threshold higher than the first threshold and the second threshold at the above-described gentle inclination, A second threshold is determined. Therefore, normally, the caliper pressure corresponding to the depression force of the brake pedal is significantly lower than the first threshold value, so that the pressurization control is performed immediately after the stoppage determination. The operation at this time corresponds to the processing being performed in the order of Step S7: Yes, Step S20, Step S8: No, Step S10: Yes, and Step S11.

  Thereafter, when the caliper pressure gradually increases and reaches within the range from the first threshold value to the second threshold value (step S8: Yes), the control shifts to holding control (time T10). Thereafter, in the same manner as described above, the control is gradually shifted to the removal control.

According to the above, the following effects can be obtained in the second embodiment.
The caliper pressure threshold setting means 22 ′ adds the correction pressure corresponding to the gradient to the first threshold and the second threshold, so that only the holding control is required on a gentle slope, and the noise due to the driving of the liquid pressure pump 4 is reduced. Can be suppressed.

[Third Embodiment]
Below, 2nd Embodiment of the brake control apparatus for vehicles which concerns on this invention is described. Since this embodiment is obtained by changing a part of the control device 20 ′ according to the second embodiment, the same components as those of the second embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 11, the control device 20 ″ includes a stop determination unit 21, a braking force control unit 23, and a gradient calculation unit 24 having the same functions as those in the second embodiment, and also compared with the second embodiment. A caliper pressure threshold value setting unit 22 ″ to which a new function is added is provided.

  The caliper pressure threshold value setting means 22 ″ has the same function as the caliper pressure threshold value setting means 22 ′ according to the second embodiment (the function of setting the first threshold value and the second threshold value based on the minimum caliper pressure during stoppage determination and In addition to having a function of correcting the first threshold value and the second threshold value in accordance with the gradient), the first force is set so that the braking force increases based on the wheel speed pulse from the wheel speed sensor (longitudinal motion detecting means) 30. It has a function for correcting the threshold value and the second threshold value (correction means for forward and backward movement) .Specifically, the caliper pressure threshold value setting means 22 ″ is while the brake lamp switch 70 is ON (see FIG. 14). ), Each time a wheel speed pulse generated from the wheel speed sensor 30 is received, the braking force is gradually increased by increasing the first threshold value and the second threshold value by a predetermined amount. Note that the first threshold value and the second threshold value that are increased for each input of the wheel speed pulse in this way are threshold values after the correction by the gradient described in the second embodiment is completed.

  Subsequently, the operation of the control device 20 ″ according to the present embodiment will be described based on the control flow shown in FIG. 12. The control flow of the present embodiment is the control flow shown in the second embodiment (FIG. 8). Since a new step S30 is added between step S20 and step S8, the new step S30 will be described only, and the description of the other steps S1 to S15 and S20 will be omitted.

  In step S30, the first threshold value and the second threshold value corrected in step S20 are corrected according to the input of the wheel speed pulse from the wheel speed sensor 30. Specifically, the processing in step S30 is a subroutine as shown in FIG. That is, after the first threshold value and the second threshold value are corrected according to the gradient in step S20, it is determined whether or not a wheel speed pulse is input (step S31). If it is determined in step S31 that a wheel speed pulse has been input (Yes), the first threshold value and the second threshold value are increased by a predetermined amount (step S32), and the process proceeds to RETURN. If it is determined that no input has been made (No), the process proceeds to RETURN. Then, after proceeding to RETURN, the process returns to the control flow of FIG. 12 and proceeds to the next step S8.

  Next, an example of the operation of the vehicle brake control device A according to the present embodiment will be described with reference to a time chart shown in FIG. In the following, the operation from time T1 to T3 and the operation after time T8 are the same as those in the second embodiment, and the description thereof will be omitted. Incidentally, FIG. 14 shows a case where the vehicle CR is stopped on a gentle slope, and the same correction pressure α as in FIG. 10A is used as the correction pressure corresponding to the gradient.

  When it is determined that the vehicle CR is in a stopped state (time T3), first, the first threshold value and the second threshold value are set based on the minimum value of the caliper pressure during the stop state continuation determination. Is added to the correction pressure α corresponding to the gradual inclination to determine a threshold value that is somewhat lower. Then, when the caliper pressure is slightly lower than the first threshold value by slowly releasing the brake pedal, the caliper pressure holding control is performed (time T11).

  At this time, if the held caliper pressure is a value that is lower than the first threshold value by a predetermined amount (a value that is higher than the second threshold value), the vehicle CR cannot be stopped on the slope. In this case, the vehicle CR starts to slide down and a wheel speed pulse is generated (time T12). When the wheel speed pulse is generated in this manner, the first threshold value and the second threshold value (not shown) are increased by a predetermined amount by the caliper pressure threshold value setting means 22 ". It is determined as S10 in S10, and the control shifts from the holding control to the pressurization control (time T12), and after the first wheel speed pulse is generated, the second wheel speed pulse is changed. Even when it is issued (time T13), the first threshold value and the second threshold value are increased by a predetermined amount by performing the above-described processing, and the caliper pressure is increased by the second pressure control. When the threshold value is exceeded, the control shifts to holding control, and thereafter, the driver performs a start operation in the same manner as described above to gradually shift to the exit control.

According to the above, the following effects can be obtained in the third embodiment.
The caliper pressure threshold setting means 22 "corrects the first threshold value and the second threshold value to be increased by a predetermined amount each time a wheel speed pulse that means the vehicle CR slides down, and shifts to pressurization control. Therefore, the braking force commensurate with the vehicle CR sliding down can be obtained.

As mentioned above, this invention is implemented in various forms, without being limited to the said embodiment.
In each of the embodiments described above, the present invention is applied to a system in which holding control is performed when the caliper pressure is within the range from the first threshold value to the second threshold value, and pressure control is performed when the caliper pressure is equal to or less than the second threshold value. However, the present invention is not limited to this. For example, by applying the present invention to a system in which holding control is started immediately after it is determined that the vehicle CR has stopped and the caliper pressure falls below a threshold value during the holding control, the present invention is applied to one threshold value. May be changed as appropriate. Further, for example, the present invention may be applied to a system that performs only pressurization control when the vehicle CR is in a stationary state and the caliper pressure falls below a threshold value without performing holding control.

The caliper pressure is not limited to be detected by the pressure sensor 50, and may be estimated by a known method from the detection result of the master cylinder hydraulic pressure sensor 80 and the driving time of the input valve 1, for example.
Further, the vehicle stop determination is not limited to the above combination, and for example, vehicle state quantities such as “accelerator opening is not more than a predetermined value” and “caliper pressure is not less than a predetermined value” may be appropriately added to the above-described conditions.

  Further, the gradual exit control does not necessarily have to be performed at a constant gradient (speed) as described above. For example, the vehicle CR includes a sensor for detecting the accelerator opening, and the accelerator at the start operation detected by the sensor is used. The brake pressure release rate (speed at which the brake pressure is released) in the release control gradually increases in proportion to the opening degree. Specifically, as in the control flow shown in FIG. 15, between step S13 and step S14 in each of the embodiments described above, step S40 for determining whether or not the accelerator switch is ON, and step S40. Based on the map shown in FIG. 16, the brake pressure removal rate is kept at the initial value (default value) when judged No, and the brake pressure removal rate is judged as Yes at Step S40. Step S42 to be changed may be provided. This map may be stored in advance as map information in the ROM of the control device. According to this, for example, when the driver wants to start quickly when starting uphill, if the accelerator pedal is depressed greatly, the brake pressure will be released quickly accordingly, so the vehicle CR can be started quickly. . In the above embodiment, the holding / pressurization control is stopped immediately after the brake lamp switch 70 is turned off (for example, step S13), but the holding / pressurization control is continued for a predetermined time. After the process is executed, the removal control (step S14) may be executed gradually. In this case, in the manual transmission vehicle, the vehicle can be prevented from sliding down until the driver meets the clutch.

It is a top view which shows the vehicle carrying the vehicle brake control apparatus which concerns on 1st Embodiment. FIG. 2 is a brake hydraulic circuit diagram of the vehicle brake control device of FIG. 1. It is a block diagram which shows the structure of the control apparatus which concerns on 1st Embodiment. It is a flowchart which shows operation | movement of the control apparatus of FIG. It is the time chart (a) which shows operation | movement of the vehicle brake control apparatus which concerns on 1st Embodiment, and the elements on larger scale of Fig.5 (a) which show a 2nd threshold value. It is a block diagram which shows the structure of the control apparatus which concerns on 2nd Embodiment. It is a map for deriving a correction pressure from an estimated inclination calculated based on a signal from a longitudinal acceleration sensor. It is a flowchart which shows operation | movement of the control apparatus of FIG. It is a flowchart which shows the process in FIG.8 S20. It is a time chart which shows operation | movement of the brake control apparatus for vehicles which concerns on 2nd Embodiment, and is made to stop at the time chart (a) which shows the operation | movement at the time of stopping on the slope of a gentle slope, and the slope of a steep slope. It is a time chart (b) which shows operation | movement at the time of a case. It is a block diagram which shows the structure of the control apparatus which concerns on 3rd Embodiment. It is a flowchart which shows operation | movement of the control apparatus of FIG. It is a flowchart which shows the process in FIG.12 S30. It is a time chart which shows operation | movement of the brake control apparatus for vehicles which concerns on 3rd Embodiment. It is a flowchart which shows the process which changes the releasing ratio of the brake pressure in gradual removal control. It is a map which shows the relationship between an accelerator opening degree and the releasing ratio of a brake pressure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 4 Hydraulic pump 20 Control apparatus 21 Stop determination means 22 Caliper pressure threshold setting means 23 Braking force control means 24 Gradient calculation means 30 Wheel speed sensor 40 Longitudinal acceleration sensor 50 Pressure sensor A Vehicle brake control apparatus

Claims (5)

Stop determination means for determining whether the vehicle has stopped from the vehicle state quantity;
Control parameter reference condition setting means for setting a first threshold value and a second threshold value, which are reference conditions for brake hydraulic pressure values used for braking force control after stoppage determination;
After stop determination, when the brake fluid pressure does not satisfy the reference condition set by the control parameter reference condition setting means, Ru retained or increased regardless braking force of the presence or absence of the driver of the brake operation control A braking force control means for performing control, and a vehicle brake control device comprising:
The control parameter reference condition setting means, among the brake fluid pressure value that varies between the said stop determination means is performing a stop determination, and sets the first threshold value based on the value that is a minimum, the first A value lower than a threshold by a predetermined amount is set as the second threshold,
The braking force control means holds the braking force when the brake fluid pressure value after stoppage determination is less than the first threshold value and greater than the second threshold value, and the brake fluid pressure value after stoppage determination is the second pressure value. A vehicular brake control device that increases a braking force when it is equal to or less than a threshold value . The vehicle brake control device according to claim 1, wherein a signal from a gradient detection unit that detects a gradient of a stop position of the vehicle is input.
The control parameter reference condition setting unit includes a reference condition correction unit that corrects the reference condition so that an influence on the braking by the gradient is suppressed based on the gradient detected by the gradient detection unit,
The brake control device for a vehicle, wherein the braking force control means holds or increases the braking force based on the corrected reference condition corrected by the reference condition correction means. The vehicle brake control device according to claim 2,
The vehicular brake control apparatus according to claim 1, wherein the reference condition correction unit corrects the current reference condition to a greater extent as the gradient detected by the gradient detection unit increases. The vehicle brake control device according to any one of claims 1 to 3, wherein a signal from a longitudinal motion detection means for detecting longitudinal motion of the vehicle is input.
The control parameter reference condition setting means includes a longitudinal movement correcting means for correcting the reference condition so that a braking force is increased based on a signal from the longitudinal movement detection means after the stop determination. Brake control device. The vehicle brake control device according to claim 4,
The back-and-forth motion detection means is a wheel speed sensor that emits one pulse each time the wheel rotates by a predetermined angle,
The forward / backward correction means gradually increases the braking force by correcting the reference condition by a predetermined amount each time a predetermined number of pulses are input from the wheel speed sensor after the stop is determined. A vehicle brake control device.

Images