JP2003312460A - Brake controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set a hill hold start judging threshold value to a proper value in response to a slope of a road face to allow sure stop even in a steep slope, to allow execution of hill hold control even in a gentle slope, and to make the both compatible. <P>SOLUTION: In this brake controller for starting the hill hold control by opening an in-flow valve 5 by a control unit CU to generate braking force for maintaining a vehicle stop condition so as not to move a vehicle, when master cylinder pressure exceeds the hill hold start judging threshold value 1 upon stopping, or when a rate of change in the master cylinder pressure exceeds the hill hold start judging threshold value 2, the control unit CU executes hill hold threshold value setting processing for setting the hill hold start judging threshold values 1,2 in response to the road face slope detected by a road face slope detecting means. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to so-called hill hold control for preventing the vehicle from moving when the driver changes the brake pedal to the accelerator pedal after stopping the vehicle by performing a braking operation. The present invention relates to a brake control device that executes.

[0002]

2. Description of the Related Art Conventionally, when a driver stops on a slope and changes his / her foot from a brake pedal to an accelerator pedal, the braking pressure in a wheel cylinder is maintained to prevent the vehicle from moving backward. A brake device that executes control is known, for example, from Japanese Patent Laid-Open No. 10-181575. In such a brake control device, as described in the above publication, the hydraulic pressure of the master cylinder is contained in the wheel cylinder by closing the solenoid valve of the existing brake circuit capable of executing the ABS control. Can be achieved with.

When executing the above-mentioned hill hold control, for example, when it is detected that the pressure of the master cylinder has fallen below a preset hill hold start judgment threshold value due to the change of the brake pedal, this is started condition. As a result, hill hold control was executed.
That is, when the pressure of the master cylinder falls below the hill hold start judgment threshold value, the solenoid valve is closed, and the vehicle pressure is stopped by closing the hydraulic pressure slightly below the hill hold start judgment threshold value into the wheel cylinder. It is possible to trap the braking pressure required for the wheel cylinders.

[0004]

However, in the above-mentioned prior art, the hill hold start determination threshold value, which is a reference for determining the start of the hill hold control, is constant, and the start determination is performed by using the master cylinder pressure and the hill. Since the judgment was made only based on the comparison with the hold start judgment threshold, there was a problem to be solved as described below.

That is, the slope of the road surface is not constant. Therefore, when the vehicle stops on a steep slope, the vehicle cannot be stopped unless a larger braking force is applied. Conversely, on a gentle slope, the vehicle can be stopped with a relatively small braking force. Therefore, when the hill hold start determination threshold value for starting the hill hold is constant, or when the hill hold start determination threshold value is set relatively low, the vehicle may move backward on a steep slope due to insufficient braking force. On the other hand, when the hill hold start determination threshold value is set relatively high, the master cylinder pressure at that time may not reach the hill hold start determination threshold value on a gentle slope, and hill hold control may not be executed on a gentle slope surface. . Therefore, since it is necessary to set the hill hold start determination threshold value to a value such that the hill hold control is surely executed even on a gentle slope, there is no choice but to set the hill hold start determination threshold value to a somewhat low value. Conventionally, it was difficult to maintain the stopped state of a vehicle on a slope that is steeper than a certain degree of slope.

Further, as described above, in the structure in which the control start judgment is made only by comparing the master cylinder pressure and the hill hold start judgment threshold value, on a steep slope, a high master cylinder pressure at which the vehicle can be stopped on this steep slope. And the hill hold start determination threshold is large, and it takes time for the master cylinder pressure to drop to the hill hold start determination threshold and the hill hold control start determination is made after the driver releases his / her foot from the brake pedal. Requires. Therefore, the vehicle may move before the driver releases his / her foot from the brake pedal to close the solenoid valve. In addition, the master cylinder pressure to be compared with this set pressure is detected by the pressure sensor, but there is variation in the output of this sensor, and the hill hold start determination threshold value is set delicately in consideration of the above problems. However, it was difficult to reflect this in control.

The present invention has been made by paying attention to the above-mentioned conventional problems, and it is possible to surely stop even on a steep slope by setting the hill hold start judgment threshold value to an appropriate value according to the road surface gradient. The main purpose is to make it possible to achieve hill hold control even on a gentle slope. Furthermore, it is intended to improve the control response of the hill hold control.

[0008]

In order to achieve the above object, the invention according to claim 1 is a braking force generating means for generating a braking force, a vehicle state detecting means for detecting a vehicle state, and a vehicle stop. When the predetermined detection value related to the hill hold control detected by the vehicle state detection means exceeds the hill hold start determination threshold value at the time, even if the driver finishes the braking operation, the braking force for maintaining the vehicle stopped state is generated by the braking force generation means. A hill hold control means for generating a hill hold control means for starting a hill hold control for preventing the vehicle from moving, and a hill hold control means for detecting a slope of a road surface on which the vehicle is stopped, the hill hold control means comprising: The control means is configured to execute a hill hold threshold setting process for setting the hill hold start determination threshold to a value according to the detected road surface gradient. That was the means.

According to a second aspect of the invention, in the brake control device according to the first aspect, as the braking force generating means, a master cylinder pressure generated by a driver's operation is introduced to generate a braking force. The master cylinder pressure detected by the master cylinder pressure sensor is used as the predetermined detection value for the hill hold control of the vehicle state detection means, and the hill hold control means uses the hill hold threshold setting process for the road surface. When the slope is steep, the hill hold start determination threshold value is set to a higher value than when the slope is gentle. According to a third aspect of the present invention, in the brake control device according to the second aspect, as the road surface gradient detecting means, a means for detecting a road surface gradient based on a detection value of the master cylinder pressure sensor when the vehicle is stopped is used. It is characterized by According to a fourth aspect of the present invention, in the brake control device according to the third aspect, the control means compares the master cylinder pressure with a first hill hold start determination threshold value when determining whether to start the hill hold control. First to do
One of the first start determination and the second start determination is performed by performing a start determination and a second start determination that compares the rate of change of the master cylinder pressure with a second hill hold start determination threshold. The hill hold control is determined to be started when the start determination is satisfied.

The invention described in claim 5 is the same as claim 1
In the brake control device according to any one of 1 to 4, in the hill hold threshold setting process, the hill hold start determination threshold is set by referring to a table input in advance. According to a sixth aspect of the present invention, in the brake control device according to any one of the first to fourth aspects, in the hill hold threshold setting process, the detected road surface gradient is substituted into a preliminarily input arithmetic expression. It is characterized in that a start judgment threshold value is set.

[0011]

In the brake control device of the present invention, the hill hold control means executes the hill hold threshold setting process when the vehicle is stopped. That is, the hill hold start determination threshold value is set according to the road surface gradient detected by the road surface gradient detecting means. As described above, in the present invention, the hill hold start determination threshold value is changed to the optimum value according to the road surface gradient without using a constant value as in the conventional case. Therefore, it is possible to reliably stop even on a steep slope. At the same time, it is possible to reliably execute the hill hold control even on a gentle slope.

According to the second aspect of the invention, the hill hold control means starts the hill hold control when the master cylinder pressure falls below the hill hold start determination threshold value when the vehicle is stopped. Also, in the hill hold threshold setting process,
When the road slope is steep, compared to when the road slope is gentle,
A relatively high value is set as the hill hold start determination threshold value. Therefore, when the driver changes the brake pedal to the accelerator pedal on a steep slope, the master cylinder pressure decreases from the high pressure corresponding to the steep slope,
Since the hill hold start determination threshold value is set to a high value on this steep slope, the master cylinder pressure falls below the hill hold start determination threshold value in a short time and hill hold control is started. Therefore, it is possible to suppress the movement of the vehicle before the hill hold control is started. Further, in the hill hold control, when the hydraulic pressure is contained in the wheel cylinder, the high pressure can be confined as compared with the conventional case, and the vehicle can be stopped reliably even on a steep slope. On the other hand, on a gentle slope, the hill hold start determination threshold value is set to a relatively low value compared to a steep slope. Therefore, even on a gentle slope, the master cylinder pressure when the vehicle is stopped becomes higher than the hill hold start determination threshold value, and the hill hold control can be reliably executed.

According to the third aspect of the invention, the road surface gradient detecting means detects the road surface gradient based on the detection value of the master cylinder pressure sensor when the vehicle is stopped. That is, when the vehicle stops on a slope, the steeper the road surface gradient, the higher the master cylinder pressure required to stop the vehicle. Therefore, when the master cylinder pressure is high when the vehicle is stopped, it is possible to determine the slope of the road such as a steep slope and a low slope, a gentle slope. In this way, by detecting the road surface slope by the master cylinder pressure, the road surface slope can be detected by an existing sensor as a brake control device that executes hill hold control, and it is necessary to add a new sensor for detecting the road surface slope. It is possible to reduce the cost of the device.

According to another aspect of the brake control device of the present invention, when the control means makes the hill hold control execution judgment when the vehicle is stopped, it is based on the master cylinder pressure detected by the pressure detection means and the change in the pressure. To do. That is, the steeper the slope on which the vehicle is stopped, the shorter the driver's stepping operation from the brake pedal to the accelerator pedal is when the vehicle restarts. The shorter the stepping is performed, the higher the rate of decrease of the master cylinder pressure. Therefore, when the slope is relatively gentle, the stepping operation from the brake pedal becomes gentle, and the pressure change rate tends to be larger than the second threshold value (the decrease rate is small). Therefore, in such a case, when the master cylinder pressure is below a first threshold value, for example, indicating that the foot has been released from the brake pedal and that the vehicle can be stopped on a slope below a predetermined angle. , It is determined that the hill hold control is performed. On the other hand, if the slope is relatively steep, the brake pedal will be stepped on faster,
Along with this, the pressure change rate tends to be smaller than the second threshold value (the decrease rate increases). Therefore, in such a case, even if the master cylinder pressure is higher than the first threshold value, it is determined that the hill hold control is performed when the pressure change rate falls below the second threshold value. In this way, by performing the hill hold control execution determination based on the master cylinder pressure and its pressure change rate, even if the slope is steep or gentle, it is possible to respond to this. Hill hold control can be executed at an appropriate timing.

According to the fifth aspect of the invention, in the hill hold threshold value setting process, the hill hold start determination threshold value is set by referring to a table input in advance based on the detected road surface gradient. Therefore, the control can be simplified. In the invention according to claim 6,
In the hill hold threshold setting process, the detected road surface gradient is substituted into a previously input arithmetic expression to set the hill hold start determination threshold. As a result, the hill hold start determination threshold value can be changed linearly and set to the optimum value at all times.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is an overall view showing a brake control device according to Embodiment 1 of the present invention corresponding to the invention described in claims 1 to 5. It should be noted that this brake control device is assumed to be installed in a vehicle having a so-called automatic transmission in which the rotation of the engine is input via a torque converter, and further the gears are shifted and output using a planetary gear. In the figure, MC is a master cylinder as a braking pressure generating means, and when the brake pedal BP is depressed, the brake fluid as a fluid is directed toward the wheel cylinder WC as a braking force generating means via the two brake circuits 1 and 2. It is of the well-known tandem type supplied. The master cylinder MC has a reservoir R for storing brake fluid.
ES is provided.

The brake circuits 1 and 2 have a so-called X pipe connection structure. That is, the brake circuit 1 is branched at the branch point 1b, and the wheel cylinder WC (FL) of the left front wheel and the wheel cylinder WC of the right rear wheel are branched.
The brake circuit 2 is configured to branch at a branch point 2b to connect the wheel cylinder WC (FR) for the right front wheel and the wheel cylinder WC (RL) for the left rear wheel.

In the present embodiment, the existing ABS unit ABSU is used to configure the device capable of performing the hill hold control. The structure will be described. In the brake circuits 1 and 2, a branch point 1
Inflow valves 5 and 5 composed of solenoid-driven normally open ON / OFF valves are provided midway downstream of b and 2b (on the wheel cylinder WC side). Further, an outflow valve 6 composed of a normally closed ON / OFF valve driven by a solenoid is provided in the middle of a drain circuit 10 connecting a position downstream of each inflow valve 5 and the reservoir 7. These inflow valve 5 and outflow valve 6 are for decompressing / holding / increasing the pressure of the wheel cylinder WC. If the inflow valve 5 is opened and the outflow valve 6 is closed, the brake circuits 1, 2 In the pressure increasing state that allows the flow between the upstream side and the downstream side, if both valves 5 and 6 are closed,
When the wheel cylinder WC is held in a state in which the brake hydraulic pressure is contained and the inflow valve 5 is closed and the outflow valve 6 is opened, the brake pressure in the wheel cylinder WC is reduced to the reservoir 7.

Conventionally, in a brake device that executes ABS control, even when the inflow valve 5 is closed by executing ABS control, when the driver releases the braking operation, A bypass circuit and a one-way valve that enables only this return are provided so as to instantly return the brake fluid to the master cylinder side.However, in the present embodiment, this bypass circuit is provided to enable hill hold control. And the one-way valve is abolished to simplify the structure of the device.

Further, a pump 4 is connected to the brake circuits 1 and 2. The pump 4 has a suction circuit 41 for absorbing the brake fluid released to the reservoir 7 by the ABS control.
Brake circuit 1, through the discharge circuit 43
The operation for returning to 2 is performed, and in this embodiment, the plunger pump driven by the motor 8 is used.

Therefore, in the present embodiment, when the wheels are about to be locked during braking, the inflow valve 5 and the outflow valve 6 are actuated as necessary to increase or maintain the pressure of the wheel cylinder WC. It is possible to execute the ABS control in which the brake fluid pressure is optimally controlled by reducing the pressure and the brake fluid released to the reservoir 7 is returned to the brake circuits 1 and 2 at any time.

The motor 8 in such ABS control
The drive of the (pump 4) and the drive of each of the inflow valve 5 and the outflow valve 6 are controlled by the control unit CU.
The control unit CU is connected to a sensor group SG that detects a running state. The sensor group SG includes a pressure sensor for detecting the pressure of the master cylinder MC,
A vehicle speed sensor for detecting a vehicle speed, a wheel speed sensor for detecting each wheel speed, and the like are included.

The control unit CU executes hill hold control in addition to the above ABS control. Therefore, this hill hold control will be described. That is, the automatic transmission is usually equipped with a torque converter, and when the engine is driven, torque is generated in the forward direction due to the so-called creep phenomenon of the torque converter, and the brake pedal BP is not operated. However, the stopped state of the vehicle can be maintained.

On the other hand, in a vehicle that executes an idle stop control for stopping the engine when the engine is stopped with the engine idling, this creep phenomenon cannot be obtained, so the braking operation is released to control. When power is lost, the vehicle will move. Therefore, in such a case, the hill hold control is executed so as to prevent the vehicle from moving by generating the braking force so that the driver does not feel uncomfortable.

FIG. 2 is a flow chart showing the flow of hill hold judgment control for judging whether to execute or cancel the hill hold control. The hill hold control determination will be described. First, in step 201, it is determined whether or not the idle stop is being performed. If the idle stop is being performed, the process proceeds to step 202, and if the idle stop is not being performed, the process proceeds to step 207. As described above, the idle stop is a control for stopping the engine when the vehicle is stopped while the engine is idling until the driver's willingness to start is indicated thereafter.

In step 202, which proceeds when the vehicle is in the idle stop, it is determined whether or not the vehicle is stopped. If the vehicle is stopped, the processing proceeds to step 203, and if not stopped, the processing proceeds to step 207.

In step 203, a hill hold start determination threshold value changing process is executed. This hill hold start determination threshold value changing process sets the hill hold start determination threshold value according to the road surface slope. In the present embodiment, as shown in FIG. 3, the table is referred to and the master cylinder at that time point is referred to. The hill hold start determination threshold value is set according to the pressure. Further, in the present embodiment, the hill hold start determination threshold value 1 (first hill hold start determination threshold value) corresponding to the master cylinder pressure and the hill hold start determination threshold value corresponding to the master cylinder pressure differential value are used as the hill hold start determination threshold value. 2 (second hill hold start determination threshold) is set, and each of the thresholds 1 and 2 is set to three levels, that is, high pressure, medium pressure, low pressure according to the master cylinder pressure. I am trying.

Next, returning to FIG. 2, in step 204,
It is determined whether or not the master cylinder pressure is less than the hill hold start determination threshold value 1. If master cylinder pressure <hill hold start determination threshold value 1, the process proceeds to step 206, and if master cylinder pressure ≧ hill hold start determination threshold value 1 is satisfied. To proceed to step 205. The hill hold start determination threshold value 1 is for detecting that the driver has released his / her foot from the brake pedal BP, and this pressure is set to a wheel cylinder pressure at which the vehicle can be stopped. That is, the high pressure threshold 1 is a pressure at which the vehicle can be stopped while detecting the release of the foot from the brake pedal BP on a predetermined steep slope, and the medium pressure threshold 1 is a predetermined moderately inclined slope. At the pressure that enables the vehicle to be stopped at the same time as detecting that the foot is released from the brake pedal BP, the low pressure threshold value 1 detects that the foot is released from the brake pedal BP on a slope having a predetermined gentle slope. In addition, the hill hold start determination threshold value 1 is set to an optimum value according to the vehicle type and the slope angle of the slope, by setting the pressure so that the vehicle can be stopped.

In step 205, it is judged whether or not the master cylinder pressure change rate (this change rate is a negative value because the pressure is decreasing) is less than a preset hill hold start judgment threshold value 2, If master cylinder pressure change rate <hill hold start determination threshold value 2, then control proceeds to step 206, and if master cylinder pressure change rate ≧ hill hold start determination threshold value 2 then this determination routine ends. It should be noted that the hill hold start determination threshold value 2 also detects a stepping operation from the brake pedal BP to the accelerator pedal, and is set to an optimum value based on experiments. Each of these determination threshold values 2 is also set to the master cylinder pressure change rate when the brake pedal BP is released on a steep, medium, or gentle slope. That is, the steeper the slope is, the faster the stepping operation from the brake pedal BP to the accelerator pedal becomes, and the smaller the rate of change of the master cylinder pressure accordingly (the pressure is in the decreasing direction in this case). Therefore, the rate of change is a negative value, and its absolute value is large). Therefore, based on the master cylinder pressure change rate, the stepping operation according to the slope angle of the slope determined in step 203 can be detected.

In step 206, if the master cylinder pressure <hill hold start judgment threshold value 1 or if the master cylinder pressure change rate <hill hold start judgment threshold value 2 in step 205, the hill hold control execution processing is executed in step 206. To do. In the present embodiment, in the hill hold control execution processing, the inflow valve 5 is turned on and closed. Therefore, since the inflow valve 6 is normally closed, the hydraulic pressure of the wheel cylinder WC is sealed and the stopped state can be maintained.

Therefore, the idle stop is in progress,
Further, when the master cylinder pressure is less than the hill hold start determination threshold value 1 when the vehicle is stopped,
Alternatively, even if the master cylinder pressure is equal to or higher than the hill hold start determination threshold value 1, if the master cylinder pressure change rate is less than the hill hold start determination threshold value 2, the hill hold control execution process is executed.

Further, it is judged in step 201 that the idle stop is not in progress, or in step 2
If it is determined in 02 that the vehicle is not stopped,
In step 207, it is determined whether or not the engine has been started. If the engine has been started, the process proceeds to step 208, and the hill hold control release processing is executed. On the other hand, if the engine has not been started, This determination routine ends. The hill hold control release process is a process of opening the inflow valve 5 by turning it off.

Therefore, when the idle stop state is lost or the vehicle is no longer stopped and the engine is started, the hill hold control release in step 208 is executed.

Next, an example of the operation when the hill hold control is carried out will be described with reference to the time chart of FIG. 4 and the time chart of FIG. That is, both figures show the case where the vehicle is stopped on the uphill road (at the time points T1 and T21), and then the vehicle is started at the time points T2 and T22, and the example of FIG. 4 is on the relatively gentle slope road. In the case of stopping, the example of FIG. 5 shows the case of stopping on a relatively steep slope. First, the example of FIG. 4 will be described. When the vehicle is stopped on an uphill road and a predetermined idle stop condition is satisfied, idle stop control is executed and the engine is stopped (time t1 in the figure). The fact that the idle stop control is being executed is indicated by the idle stop control being ON in this figure.
In addition, since the brake pedal is strongly depressed to stop on such an uphill road, the initial brake fluid pressure is high.

After that, when the driver performs an operation to switch from the brake pedal BP to an accelerator pedal (not shown) in order to perform a start operation, the master cylinder pressure (brake fluid pressure) decreases and it is determined at the time t2 that the hill hold is started. Below threshold 1, this results in steps 201 → 202 → 203 → 2
Hill-hold control execution processing is performed based on the flow of 04 → 206, and the inflow valve 5 is closed. Therefore, the brake fluid pressure at this time is trapped in the wheel cylinder WC, and the stopped state can be maintained. By the way, on a gentle slope, the changeover from the brake pedal BP to the accelerator pedal is gentle, and the rate of change of the cylinder pressure is as shown in the figure.
Never falls below.

After that, when a predetermined engine restart condition such as depression of the accelerator pedal is satisfied and the engine (not shown) is started (t3), steps 201or202 → 207 in the hill hold control judgment of FIG. →
According to the determination of 208, the hill hold control release processing is executed to open the inflow valve 5.

As a result, the brake fluid in the wheel cylinder WC is returned to the master cylinder MC, the braking force is lost, and the vehicle starts when the engine starts (at the time T2).

Next, the operation on the steep slope shown in FIG. 5 will be described. When the vehicle is stopped on a steep slope and a predetermined idle stop condition is satisfied, idle stop control is executed and the engine is stopped (at time t21 in the figure). This operation is similar to the case of FIG.

After that, when the driver performs an operation to switch from the brake pedal BP to an accelerator pedal (not shown) in order to perform a starting operation, this step operation is quickly performed on a steep uphill road. Therefore, the rate of decrease of the master cylinder pressure (brake hydraulic pressure) becomes larger than that in the example shown in FIG.
In the example of FIG. 4, the change in brake fluid pressure did not fall below the hill hold start determination threshold value 2, whereas in the example of FIG. 5, the master cylinder pressure (brake fluid pressure) falls below the hill hold start determination threshold value 1. At the previous time point, the rate of change in brake fluid pressure falls below the hill hold start determination threshold value 2 (time point t22). Therefore, at this point, the hill hold control execution process is performed and the inflow valve 5 is closed. Therefore, as shown in the figure, a brake fluid pressure higher than the hill hold start determination threshold value 1 is sealed in the wheel cylinder WC, and it is possible to reliably prevent the vehicle from moving backward even on a steep uphill road.

After that, when the predetermined engine restart condition is satisfied and the engine is restarted (t23), the hill hold control release process is executed and the inflow valve 5 is opened.
The braking force disappears and the vehicle starts (T22). In this embodiment, it takes about 100 msec from the restart of the engine to the opening of the inflow valve 5 by the hill hold control release processing. this is,
This is because the variation in the time from when the starter motor (not shown) is driven to restart the engine to when the engine is actually driven is taken into consideration.

As described above, in the present embodiment, the hill hold start determination threshold value 1 and the hill hold start determination threshold value 2 are set based on the road surface slope determination when the vehicle is stopped.
Since the optimum threshold value is selected from the three threshold values of the high pressure threshold, the medium pressure threshold, and the low pressure threshold,
It is possible to detect in a short time that the foot has been released from the brake pedal BP at each gradient and execute hill hold control, and at this time, the pressure corresponding to the road gradient can be contained in the wheel cylinder WC. Therefore, the vehicle can be reliably stopped at each slope without moving. Further, in the present embodiment, since the existing master cylinder pressure sensor is used in the device that executes the hill hold control as the means for detecting the road surface gradient,
Since no sensor is added, the cost can be reduced.

Further, in the present embodiment, not only the comparison of the master cylinder pressure (brake hydraulic pressure) with the hill hold start determination threshold value 1 (static pressure comparison) but also the change of the master cylinder pressure in the hill hold control execution determination. The rate (brake hydraulic pressure change rate) and the hill hold start determination threshold 2 are compared (dynamic pressure comparison), and the hill hold control is executed when either one of the comparison conditions is satisfied.
While setting the hill hold start determination threshold value 1 so as not to be too high, the hill hold start determination can be made in a short time without a response delay even when the vehicle is set to an appropriate value that can be stopped on a slope. At the same time, the brake fluid having a pressure higher than the hill hold start determination threshold value 1 can be confined in the wheel cylinders WC, so that the hill hold can be surely executed even on a steep slope.

Further, in the embodiment, since the apparatus is configured by a simple unit that executes the existing ABS control,
It is possible to obtain an effect that it can be configured at low cost and small size, and that hill hold control can be executed by a low cost and small device. Further, with this configuration, in order to perform the hill hold control, the inflow valve 5 can be closed and the hydraulic pressure can be contained in the wheel cylinder WC.
The circuit for bypassing the inflow valve 5 provided in the conventional ABS control device and the one valve provided in each circuit and allowing only the return from the wheel cylinder WC are eliminated.
Therefore, it is possible to further simplify the device and achieve cost reduction and size reduction.

(Second Embodiment) Next, a brake control device according to a second embodiment of the invention corresponding to claims 1 to 4 and 6 will be described. In the second embodiment, the contents of the hill hold threshold variable processing executed in step 203 are different from those in the first embodiment. That is, in the second embodiment, the hill hold start determination threshold value 1 and the hill hold start determination threshold value 2 are obtained by performing a calculation for multiplying the master cylinder pressure detected when the vehicle is stopped by a preset coefficient. FIG. 6 shows this, and both hill hold start determination threshold 1 = MPa and hill hold start determination threshold 2 = MPa / S, master cylinder pressure × ○○%, master cylinder pressure × ΔΔ% I'm trying to ask. Therefore, in the second embodiment, the hill hold start determination threshold 1 and the hill hold start determination threshold 2 can be set steplessly, and can be set to more optimal values. In addition, these ○○%, △
It is desirable that the optimum value of Δ% be appropriately selected according to the vehicle characteristics. Further, other operational effects are the same as those in the first embodiment, and therefore the description thereof is omitted.

(Third Embodiment) Next, a brake control device according to a third embodiment will be described. This Embodiment 3
Is an example in which the configuration of the brake device is different from that of the first embodiment. In the third embodiment, when the driver performs a braking operation, the brake assists the braking operation to increase the wheel cylinder pressure. It is an example applied to a brake control device capable of executing assist control. FIG. 7 is a brake circuit diagram showing a main part of the brake control device of the third embodiment, and the configuration will be described below based on this diagram. In the description of this configuration, configurations common to those of the first embodiment will be assigned the same reference numerals as those of the first embodiment, and description thereof will be omitted.
Only the points of difference in configuration from the first embodiment will be described.

In the brake circuits 1 and 2, a gate valve 301 is provided upstream of the discharge position of the pump 4. The gate valve 301 normally connects the brake circuits 1 and 2 to the illustrated communication state. In this communication state, the flow is allowed in any direction from upstream to downstream and from downstream to upstream. On the other hand, when the driver performs a braking operation to generate a master cylinder pressure, the master cylinder pressure is used as a pilot pressure to switch to a closed state. However, in this valve-closed state, the one-way valve 302 functions as shown to stop the reverse flow from the wheel cylinder side to the master cylinder side, but allows the flow in the reverse direction. Further, a bypass circuit 310 is provided in parallel with the gate valve 301. The bypass cylinder 310 includes a wheel cylinder W.
A one-way valve 311 that allows only the flow from the C side to the master cylinder MC side is provided. Accordingly, even when the gate valve 310 is closed, when the driver finishes the braking operation, the hydraulic pressure of the wheel cylinder WC returns to the master cylinder MC.

The reservoir 307 is the suction circuit 303.
This suction circuit 3 is connected to the master cylinder side via
03 of the valve mechanism 3 at the connection end of the reservoir 307.
04 are provided. When the brake fluid is stored in the reservoir 307, the valve mechanism 304 is in a closed state to shut off the flow from the suction circuit 303 to the reservoir 307, while the reservoir 307 does not store the brake fluid. In the state, the piston 305 causes the valve mechanism 30 to
The valve body of No. 4 is pushed up to allow the flow from the suction circuit 303 to the reservoir 307.

Therefore, when the driver performs a braking operation,
The gate valve 301 closes. At the same time, a control unit (not shown) executes an assist control to drive the pump 4, and the brake fluid sucked by the pump 4 is applied to the gate valve 3
It is discharged downstream from 01. Therefore, a pressure higher than the master cylinder pressure is supplied to the wheel cylinder WC. Even in the third embodiment, the wheel cylinder W is closed by closing the inflow valve 5 during the hill hold control.
The braking force is maintained by containing the hydraulic pressure in C. In the third embodiment, since the wheel cylinder pressure is higher than the master cylinder pressure, at the start of the hill hold control, the wheel cylinder WC is confined to a higher pressure than the master cylinder MC, so that the vehicle The stopped state can be reliably formed.

Although the embodiments have been described with reference to the drawings, the present invention is not limited to the configurations of the above embodiments. For example, in the first embodiment, the hill hold start determination thresholds 1 and 2 are set in three stages, but they may be set in any number of stages if there are two or more stages. Further, in the first embodiment, two thresholds such as the hill hold start determination thresholds 1 and 2 are set, but only the hill hold start determination threshold 1 corresponding to the master cylinder pressure may be set.

Further, in the first embodiment, as the road surface gradient detecting means, the means for judging the road surface gradient on the basis of the detected master cylinder pressure is shown. However, a means for directly detecting the road surface gradient such as an acceleration sensor is used. You may use.

Further, in the embodiment, the wheel cylinder operated by the master cylinder pressure is shown as the braking force generating means, but the braking force generating means is not limited to this and is called a so-called brake-by-wire. A brake device may be used that supplies braking fluid pressure to the wheel cylinders by using a hydraulic pressure generating means such as a pump in response to an operation, or a brake that operates a brake pad by a motor in response to a braking operation by a driver. It may be applied to the device. The point is that the hill hold start determination threshold value may be changed according to the detected road surface gradient. Further, although the brake fluid (oil) is used as the fluid for operating the wheel cylinder, it is also applicable to a structure using gas such as air.

Further, in the embodiment, the example applied to the AT vehicle is shown, but the present invention can also be applied to a vehicle equipped with a manual transmission or a continuously variable transmission.
Furthermore, in the embodiment, two valves, an inflow valve and an outflow valve, are used as the pressure control valve, but the first position is that the upstream and downstream are connected and the drain circuit is blocked, and the upstream side is blocked and the downstream and drain circuit are connected. It is also possible to use one pressure control valve of a type that can be switched to the three positions of the second position, the upstream position, the downstream position, and the third position where the drain circuit is shut off. In this case, the control position is switched to the second position during the control release process.

[Brief description of drawings]

FIG. 1 is an overall view showing a brake control device according to a first embodiment.

FIG. 2 is a flowchart showing a control flow of hill hold control in the first embodiment.

FIG. 3 is an explanatory diagram showing a hill hold threshold value setting process according to the first embodiment.

FIG. 4 is a time chart showing an operation example on a gentle slope according to the first embodiment.

FIG. 5 is a time chart showing an operation example on a steep slope according to the embodiment.

FIG. 6 is an explanatory diagram showing a hill hold threshold value setting process according to the second embodiment.

FIG. 7 is a circuit diagram showing a main part of a brake control device according to a third embodiment.

[Explanation of symbols]

1, 2 brake circuit 4 pumps 5 Inflow valve 6 Outflow valve 7 Reservoir 10 drain circuit 41 Inhalation circuit 43 Discharge circuit CU control unit (hill hold control means) MC master cylinder WC wheel cylinder (braking force generation means)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiro Nakamizo             1370 Onna, Atsugi, Kanagawa             Nissia Jex F-term (reference) 3D046 BB02 BB26 CC02 DD04 EE01                       HH02 HH05 HH16 HH17 HH22                       HH49 JJ02

Claims (6)

[Claims] 1. A hill-hold start determination threshold value that is a predetermined detection value for hill-hold control detected by the vehicle-state detecting means when the vehicle is stopped, a braking-force generating means that generates a braking force, a vehicle-state detecting means that detects a vehicle state. When the value exceeds, the hill hold control means for starting the hill hold control for generating the braking force for maintaining the vehicle stopped state by the braking force generation means and preventing the vehicle from moving even if the driver finishes the braking operation, In the brake control device provided with, a road surface slope detecting means for detecting the slope of the road surface on which the vehicle is stopped is provided, and the hill hold control means sets the hill hold start judgment threshold value to a value according to the detected road surface slope. A brake control device, wherein a hill hold threshold setting process is executed. 2. The brake control device according to claim 1, wherein the braking force generating means is provided with a wheel cylinder that introduces a master cylinder pressure generated by a driver's operation to generate a braking force. The master cylinder pressure detected by the master cylinder pressure sensor is used as the predetermined detection value relating to the hill hold control of the detection means, and the hill hold control means, in the hill hold threshold setting processing, when the road surface slope is steep when it is loose. In comparison, the brake control device is characterized in that a high value is set as a hill hold start determination threshold value. 3. The brake control device according to claim 2, wherein, as the road surface gradient detecting means, a means for detecting a road surface gradient based on a detection value of the master cylinder pressure sensor when the vehicle is stopped is used. Brake control device. 4. The brake control device according to claim 3, wherein the control means determines when hill hold control is started.
A first start determination that compares the master cylinder pressure with a first hill hold start determination threshold value to make a start determination, and a second start determination that compares the rate of change of the master cylinder pressure with a second hill hold start determination threshold value. A brake control device, wherein a start determination is performed, and when one of the first start determination and the second start determination is satisfied, it is determined that the hill hold control is started. 5. The brake control device according to claim 1, wherein in the hill hold threshold setting process, a hill hold start determination threshold is set by referring to a table input in advance. Brake control device characterized by. 6. The brake control device according to claim 1, wherein in the hill hold threshold setting process, the detected road surface gradient is substituted into an arithmetic expression input in advance to set a hill hold start determination threshold value. A brake control device characterized by being set.