JP3223738B2 - Vehicle brake control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control different from a driver's brake operation, for example, an anti-skid control for preventing a wheel from being locked, a traction control for preventing a wheel spin, and a rear-end collision. The present invention relates to a vehicle brake control device capable of performing automatic braking for prevention and left and right wheel brake control for controlling a horizontal surface behavior of the vehicle.

[0002]

2. Description of the Related Art As a brake control device for a vehicle of this type, the present applicant has already proposed the following brake control device in Japanese Patent Application Laid-Open No. 4-8767.
In other words, the pressure from the master cylinder in response to the driver's brake operation is supplied to the wheel cylinder via the pressure synthesizer, while the pressure from another pressure source is input and any output is electronically controlled. The output pressure from the electronic control pressure system that generates the pressure is supplied to the above-described pressure synthesizer, and the output pressure generates the brake pressure from the pressure synthesizer to the wheel cylinder. This enables a brake control different from the brake operation by the driver.

On the other hand, conventionally, during normal service braking, a pressure synthesizer is operated by the output pressure from the electronic control pressure system, thereby boosting the brake fluid pressure from the master cylinder to the wheel cylinder. Since the electronic control pressure system can also have a boosting function, the booster can be omitted from the master cylinder pressure system, and the master cylinder pressure can be applied to the pressure control valve of the electronic control pressure system. Has also been made to be appropriate in accordance with the master cylinder pressure.

[0004]

However, in such a conventional brake control device, the electronic control pressure system is also provided with a boosting function at the time of normal service braking. When this occurs and the output pressure to the pressure synthesizer no longer occurs, the driver's treading force increases, and it is necessary to provide an extra mechanism for the pressure control valve of the electronic control pressure system. However, there has been a problem that the pressure control valve becomes large.

[0005] In view of the above, in a vehicle running condition in which a boosting function is provided to a brake operating pressure system operated by a driver and wheel braking control other than braking corresponding to the driver's brake operating force is required, the wheel is operated. It was conceived that the connection to the cylinder was switched from the brake operation pressure system to the electronic control pressure system and the operation shown in FIG. 7 was obtained.

[0008] FIG. 7 (a), in case of pressure reduction control the output pressure of the electronically controlled hydraulic system, line a is the master cylinder pressure from brake operation pressure circuit has started operating in the same time at time t ₁ Even if the pressure is switched to the dotted line b, which is the output pressure of the electronic control pressure system, as shown by the one-dot chain line c, which is the brake fluid pressure supplied to the wheel cylinder, the pressure is smoothly reduced, giving a great sense of discomfort to the driver. Absent.

However, in FIG. 7B, when the output pressure of the electronic control pressure system is controlled to increase, if the switching control is performed at time t ₁ as in the case of the pressure reduction control, the electronic control pressure system can be controlled. When the dotted line b, which is the output pressure of the vehicle, switches to the solid line a, which is the master cylinder pressure, as indicated by the one-dot chain line c, which is the brake fluid pressure supplied to the wheel cylinder, at time t
_As a result, the driver feels discomfort such as kickback to the brake pedal due to the pressure step.

As a countermeasure, in a vehicle running situation where only wheel braking corresponding to the driver's braking force is required,
When the electronic control pressure system is controlled to be equal to the brake operation pressure from the brake operation pressure system, the one-dot chain line c which is the brake fluid pressure supplied to the wheel cylinder is smooth as shown in FIG. Although it does not give a sense of incongruity, since the electronic control pressure system is always controlled, the pressure source of the electronic control pressure system is operated even when braking corresponding to the brake operating force is required, resulting in unnecessary energy consumption. Would.

The present invention solves the problem of increasing the driver's treading force when an abnormality occurs due to the provision of a boosting function in the electronic control pressure system. To propose a brake control device for vehicles that also eliminates the problem of giving the driver a sense of incongruity due to kickback to the brake pedal due to a pressure step when switching to the control pressure system, and to constantly control the electronic control pressure system. It is an object of the present invention to provide a vehicle brake control device that also prevents the energy efficiency from deteriorating.

[0010]

According to the present invention, there is provided a brake control device for a vehicle according to the present invention, which includes a booster for generating a brake operation pressure corresponding to a driver's brake operation force. A brake operating pressure system, an electronic control pressure system that receives a pressure from an external pressure source as input and generates a brake control pressure adjusted based on an external command value, and a brake operating pressure from the brake operating pressure system And a switching valve for selecting one of the brake control pressures from the electronic control pressure system and supplying the selected brake control pressure to the wheel cylinder as brake fluid pressure. Switching control means for communicating the electronic control pressure system with the wheel cylinder by a valve, and communication between the electronic control pressure system and the wheel cylinder bypassing the switching control means When the brake control pressure generated from the electronic control pressure system and the brake control pressure generated from the electronic control pressure system become equal to or greater than the brake operation pressure generated from the brake operation pressure system, the electronic control pressure system bypasses the switching control means and the wheel. A check means for allowing only a liquid flow to the cylinder is provided.

In the vehicle brake control device according to a second aspect of the present invention, the switching control means includes:
A switching valve for supplying the brake operating pressure from the brake operating pressure system to the wheel cylinder as brake fluid pressure in a normal state and supplying the output pressure from the electronic control pressure system to the wheel cylinder as brake fluid pressure by control; It is characterized by the following.

Furthermore, in the brake control apparatus for a vehicle according to the present invention, the switching control means communicates normally between the path between the brake operation pressure system and the wheel cylinder and shuts off by control. Open / close switching valve,
When the brake control pressure normally generated from the electronic control pressure system becomes equal to or higher than the brake operation pressure generated from the brake operation pressure system between the path between the electronic control pressure system and the wheel cylinder, the electronic control pressure A check valve that permits only the liquid flow from the system to the wheel cylinder and communicates by control.

[0013]

According to the present invention, in the vehicle brake control device according to the present invention, in a vehicle running condition in which only wheel braking corresponding to the driver's brake operation force is required, the vehicle brake control device can respond to the driver's brake operation force. A brake operation pressure system having a booster that generates a brake operation pressure communicates with the wheel cylinder, and supplies the brake operation pressure to the wheel cylinder as brake fluid pressure.

Therefore, even when the electronic control pressure system is abnormal, boosting cannot be disabled. In addition, since the electronic control pressure system is not provided with a boost function, there is no need to provide an extra mechanism for the pressure control valve of the electronic control pressure system, and this pressure control valve becomes large. There is no problem.

At this time, in a vehicle running condition where only wheel braking corresponding to the driver's brake operating force is required,
Since the electronic control pressure system does not operate including the pressure source, it is possible to prevent the deterioration of energy efficiency caused by constantly controlling the electronic control pressure system.

In a vehicle running condition in which wheel braking control other than braking corresponding to the driver's braking operation force is required, when the output pressure of the electronic control pressure system is to be reduced, the electronic control pressure system is first activated. After that, the switching control means communicates the electronic control pressure system with the wheel cylinder, and supplies the output pressure of the electronic control pressure system, which has been reduced in pressure, as brake fluid pressure.

Further, when increasing the output pressure of the electronic control pressure system, first, the electronic control pressure system is operated,
When the output pressure of the electronic control pressure system becomes equal to or higher than the master cylinder pressure, check means for bypassing the switching control means and allowing only the liquid flow from the electronic control pressure system to the wheel cylinder is opened, and the electronic control pressure system is opened. Output pressure is applied to the wheel cylinder, and thereafter, for example, by a response from open / close detection means for detecting opening / closing of the check means, the switching control means causes the electronic control pressure system to communicate with the wheel cylinder,
The output pressure of the electronic control pressure system is supplied as brake fluid pressure.

At the moment of switching by the switching control means, as is apparent from the above description, when the output pressure of the electronic control pressure system is controlled to be reduced, the brake fluid pressure decreases at the instant of switching. Since the pressure reduction control is performed, the driver does not have to feel uncomfortable.

In the case where the output pressure of the electronic control pressure system is controlled to increase, the output pressure of the electronic control pressure system is once supplied to the wheel cylinders via the check means to enable smooth switching. Therefore, it is possible to eliminate a sense of discomfort to the driver.

In the brake control apparatus for a vehicle according to the present invention, the switching control means supplies a brake operation pressure from the brake operation pressure system to a wheel cylinder as brake fluid pressure in a normal state. With the provision of a switching valve for supplying the output pressure from the electronic control pressure system to the wheel cylinder as brake fluid pressure, in addition to the above-described operation and effect, the path switching control can be performed in one place, so that efficient control can be achieved. It can be performed.

According to a third aspect of the present invention, in the vehicle brake control apparatus according to the third aspect, the switching control means communicates normally between a path between the brake operation pressure system and a wheel cylinder and opens and closes by control. A switching valve, between the path of the electronic control pressure system and the wheel cylinder, when the brake control pressure generated from the electronic control pressure system in a normal state becomes equal to or higher than the brake operation pressure generated from the brake operation pressure system, A check valve that allows only the liquid flow from the electronic control pressure system to the wheel cylinder and communicates by control is provided. In addition to the above-described effects, a path that connects the electronic control pressure system to the wheel cylinder is provided. In addition to the fact that the apparatus is not complicated and large, the two-position switching valve is used, so that the processing accuracy of the switching valve itself is not strict and low. It is possible to reduce the list of.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a first embodiment of a vehicle brake control device according to the present invention, in which only one of the four wheels is shown for simplification of description.

First, the structure will be described. Reference numeral 1 designates a master cylinder having a brake pedal 8 and a brake booster 9, which generates a boosted master cylinder pressure when the driver depresses the brake pedal 8. The two-position three-way output switching valve 5 communicates with each wheel. This corresponds to a brake operating pressure system with a booster.

Reference numeral 4 denotes a pump 3 which is another pressure source.
This is an electro-hydraulic control valve that regulates the pressure from the engine and generates an arbitrary output pressure, and is in communication with a two-position three-way output switching valve 5 for each wheel. This corresponds to an electronic control pressure system.

At this time, reference numeral 2 denotes a wheel cylinder for braking the wheels, and a two-position three-way output switching valve 5 communicates the master cylinder 1 and the wheel cylinder 2 in a normal state.
Switching is controlled by the control so that the output port 4c of the electro-hydraulic control valve communicates with the wheel cylinder 2. This corresponds to switching control means.

A check valve 6 serving as a non-return means is provided between the path connecting the output port 4c of the electro-hydraulic control valve and the wheel cylinder 2 so as to bypass the output switching valve 5 and to control the electro-hydraulic control valve. The output pressure is supplied to the wheel cylinder 2 only when the output pressure is higher than the master cylinder pressure.

Further, the check valve 6 is provided with an open / close switch 7 as open / close detecting means for turning on the contact when the valve is opened and turning off the contact when closed.

Reference numeral 100 designates various sensors for detecting the environmental condition of the running vehicle, a pressure sensor 10 provided between the master cylinder 1 and the output switching valve 5 for detecting the master cylinder pressure, and an open / close switch 7. Pump 3, electro-hydraulic control valve 4 and output switching valve 5
Is a control unit for controlling the

Next, the operation will be described. First, in a vehicle running condition in which only wheel braking corresponding to the driver's brake operating force is required (hereinafter referred to as normal braking), the output switching valve 5 is in a normal state and boosted by the brake booster 9. The master cylinder pressure is directly supplied to the wheel cylinder 2 as a brake oil pressure corresponding to the depression of the brake pedal 8 by the driver to secure the braking force.

At this time, the electronic control pressure system is in an inoperative state, and the hydraulic pressure supply operation by the pump 3 and the pressure regulation control to the electronic hydraulic control valve 4 are not performed.

As a result, the electro-hydraulic control valve 4 can be downsized because the booster mechanism is not required, and when the output pressure is no longer generated due to an abnormality in the electronic control pressure system, the brake operating pressure is reduced. The system ensures a boost function and does not cause a decrease in braking force.

Further, it is not necessary to perform pressure regulation control for the electro-hydraulic control valve 4 during normal braking, and it is possible to prevent extra energy loss due to the hydraulic pressure supply operation of the pump 3.

On the other hand, a vehicle running that requires wheel braking control other than braking corresponding to the driver's braking force, such as anti-skid control to prevent wheel braking lock and traction control brake control to prevent wheel spin. The situation (hereinafter referred to as brake hydraulic pressure control) will be described with reference to FIG. 3 attached separately from FIG.

FIG. 3A is a time chart showing various pressure relationships when the output pressure of the electro-hydraulic control valve is controlled to be reduced, and FIG. 3B is a time chart showing various pressure relationships when the output pressure is controlled to be increased. ,
The master cylinder pressure corresponding to the depression of the brake pedal 8 by the driver, the dotted line b is the output pressure of the electro-hydraulic control valve 4,
The dashed line c indicates the brake hydraulic pressure supplied to the wheel cylinder 2.

First, when the output pressure of the electro-hydraulic control valve is controlled to be reduced, the control unit 100 activates the pump 3 in accordance with a control command, regulates the pump pressure by the electro-hydraulic control valve 4, and controls the output switching valve. 5 is switched from a position in which the master cylinder 1 communicates with the wheel cylinder 2 to a position in which the output port 4c of the electro-hydraulic control valve communicates with the wheel cylinder 2, and the output pressure of the electro-hydraulic control valve 4 that has been reduced in pressure is controlled. The brake hydraulic pressure is supplied to the wheel cylinder 2.

At this time, as shown in FIG.
Is performed at time t ₁ , a delay time T occurs until the dotted line b, which is the output pressure of the electro-hydraulic control valve 4, rises to the actual value, and the brake hydraulic pressure supplied to the wheel cylinder 2 during that time It is lowered as a chain line c, but does not give a sense of discomfort due to the pressure difference in level when switching the original pressure reduction control until time t ₂ for the driver since it is intended.

Further, when increasing the output pressure of the electro-hydraulic control valve, the control unit 100 only operates the pump 3 according to a control command and regulates the pump pressure by the electro-hydraulic control valve 4. Then, the output switching valve 5 supplies the output pressure of the electro-hydraulic control valve 4 whose pressure has been controlled to the check valve 6 provided between the bypass routes, while keeping the master cylinder 1 and the wheel cylinder 2 in communication.

The check valve 6 is opened when the output pressure of the electro-hydraulic control valve 4 becomes higher than the master cylinder pressure, and the output pressure of the electro-hydraulic control valve 4 is applied to the wheel cylinder 2. At the same time, the contact of the open / close switch 7 is turned on and transmitted to the control unit 100. In response to the transmission signal, the control unit 100 performs control to switch the output switching valve 5 to a position at which the output port 4c of the electro-hydraulic control valve communicates with the wheel cylinder 2, and reduces the output pressure of the electro-hydraulic control valve 4 to the brake hydraulic pressure. And supplied directly to the wheel cylinder 2.

At this time, if the switching control of the output switching valve 5 is performed at time t ₁ from FIG. 3B, the delay until the dotted line b, which is the output pressure of the electrohydraulic control valve 4, rises to the actual value. Time T is generated, but the output port 4 of the electro-hydraulic control valve is
Since the load is applied between the path from c and the check valve 6, the hydraulic rigidity of that portion is higher than that of the wheel cylinder 2, and therefore, the pressure increases to the master cylinder pressure in a short time. Therefore, the brake oil pressure supplied to the wheel cylinder 2 is equal to the delay time T
Is controlled smoothly as indicated by the dashed line c, and the driver does not feel uncomfortable due to the pressure step at the moment of switching.

Next, the operation of this embodiment will be described with reference to the flowchart of the control program shown in FIG. First, at step 50, the control unit 100 receives an input signal from various sensors that detect a vehicle environment state during traveling, such as a wheel rotation sensor and a throttle opening sensor, for example.
It is determined whether or not brake oil pressure control such as anti skit control or traction control brake control is required.

If not, step 51
The control unit 100 transmits a switching control release command to the output switching valve 5, and connects the master cylinder 1 and the wheel cylinder 2 to perform normal braking.

Conversely, if it is determined in step 50 that the brake oil pressure control is necessary, the process proceeds to step 52, where it is determined whether or not the brake oil pressure control is a pressure increase control. The pressure is controlled to be adjusted to the required output pressure by the electro-hydraulic control valve 4.

If it is determined in step 52 that the pressure increase control is not performed, the process proceeds to step 54, where the control unit 1
00 transmits a switching control command to the output switching valve 5, communicates the output port 4c of the electro-hydraulic control valve with the wheel cylinder 2, and performs pressure reduction control of the brake hydraulic pressure.

Conversely, if it is determined in step 52 that the pressure increase control is to be performed, the process proceeds to step 53, and whether or not the ON signal of the open / close switch 7 for detecting that the check valve 6 has been opened has been input to the control unit 100. Is determined.

At this time, if an ON signal is input, the process proceeds to step 54, where a switching control command is transmitted to the output switching valve 5. If an OFF signal is input, the process proceeds to step 51, where a switching control release command is transmitted. And perform normal braking.

The above command is sent to the control unit 10
0, steps 53 and 54 correspond to control delay means for delaying the switching control means.

FIG. 2 is a diagram showing the configuration of the second embodiment of the present invention. In this embodiment, an open / close switching valve 11 which normally communicates between a master cylinder 1 having a brake pedal 8 and a brake booster 9 and a wheel cylinder 2 and shuts off by control, an electro-hydraulic control valve 4 and a wheel cylinder An electromagnetic operated check valve (OP check valve) 12, which is a check valve that is normally connected between the output port 4c of the electro-hydraulic control valve and the control valve and allows the fluid flow to the wheel cylinder 2, and communicates with the control valve. Equipped with control unit 100
Is controlled by This corresponds to switching control means.

Next, the operation will be described. First, during normal braking, the open / close switching valve 11 and the OP check valve 12 are in a normal state, the master cylinder 1 and the wheel cylinder 2 communicate with each other, and the master cylinder pressure corresponding to the depression of the brake pedal 8 by the driver is applied to the brake. The hydraulic pressure is supplied to the wheel cylinder 2 to secure the braking force.

In this case, the electronic control pressure system is in a non-operating state, and the operation of supplying hydraulic pressure by the pump 3 and the control of pressure adjustment to the electronic hydraulic control valve 4 are not performed.

Thus, the electro-hydraulic control valve 4 can be reduced in size because the booster mechanism is not required, and when the output pressure no longer occurs due to an abnormality in the electronic control pressure system, the brake operating pressure is reduced. The system ensures a boost function and does not cause a decrease in braking force.

Further, it is not necessary to perform pressure regulation control for the electro-hydraulic control valve 4 during normal braking, and it is possible to prevent extra energy loss due to the hydraulic pressure supply operation of the pump 3.

On the other hand, the case of the brake hydraulic pressure control will be described with reference to FIG. 3 attached separately from FIG.

First, when the output pressure of the electro-hydraulic control valve is controlled to be reduced, the control unit 100 operates the pump 3 according to a control command, regulates the pump pressure by the electro-hydraulic control valve 4, and controls the open / close switching valve 11. Is supplied to the wheel cylinder 2 only when the output pressure of the electro-hydraulic control valve 4 is equal to or higher than the master cylinder pressure. The switching control is performed from the stop position to a position communicating with the electro-hydraulic control valve output port 4c and the wheel cylinder 2, and the output pressure of the electro-hydraulic control valve 4 that has been reduced in pressure is supplied to the wheel cylinder 2 as brake oil pressure.

At this time, as shown in FIG.
1 and the switching control of the OP check valve 12 are performed at time t ₁ , a delay time T occurs until the dotted line b, which is the output pressure of the electro-hydraulic control valve 4, rises to the actual value. Although the brake hydraulic pressure supplied to the vehicle decreases as indicated by the one-dot chain line c, since the purpose is to reduce the pressure, the driver does not feel discomfort such as a sudden change in the braking force due to the pressure step at the moment of switching.

Further, when increasing the output pressure of the electro-hydraulic control valve, the control unit 100 first activates the pump 3 according to a control command, regulates the pump pressure by the electro-hydraulic control valve 4, and switches between opening and closing. The valve 11 is in a position for shutting off the master cylinder 1 and the wheel cylinder 2, and the OP check valve 12 is in a non-return position for supplying the wheel cylinder 2 only when the output pressure of the electrohydraulic control valve 4 becomes higher than the master cylinder pressure. Electro-hydraulic control valve 4 with pressure increase control
Is supplied to the OP check valve 12. When the output pressure becomes equal to or higher than the master cylinder pressure, the OP check valve 12 is opened, and the output pressure of the electronic control valve 4 is applied to the wheel cylinder 2.

The OP check valve 12 is also provided with an open / close switch 7 so that the output pressure of the electro-hydraulic control valve 4 becomes higher than the master cylinder pressure and the OP check valve 12 supplied to the wheel cylinder 2 is opened. , The contact of the open / close switch 7 is turned ON and the control unit 100
Is transmitted to

In response to the transmission signal, the control unit 100 controls the switching of the OP check valve 12 from the check position to the communicating position, and uses the output pressure of the electro-hydraulic control valve 4 as the brake oil pressure directly to the wheel cylinder 2. To supply.

At this time, as shown in FIG.
1 and the switching control of the OP check valve 12 are performed at time t ₁ , a delay time T is generated until the dotted line b, which is the output pressure of the electro-hydraulic control valve 4, rises to the actual value. The load is between the output port 4c of the valve and the path from the OP check valve 12, and since the hydraulic rigidity of this portion is higher than that of the wheel cylinder 2, the pressure increases to the master cylinder pressure in a short time. Therefore, the brake oil pressure supplied to the wheel cylinder 2 has a short delay time T and is smoothly controlled as indicated by a dashed line c, so that the driver does not feel uncomfortable due to the pressure step at the moment of switching.

Next, the operation of this embodiment will be described with reference to the flowchart of the control program shown in FIG.

First, in step 50, brake oil pressure control such as anti-skid control and traction control brake control is performed based on input signals from various sensors for detecting the environmental condition of a running vehicle such as a wheel rotation sensor and a throttle opening sensor. It is determined whether it is necessary.

If not, step 51
The control unit 100 transmits a switching control release command to the opening / closing switching valve 11 and the OP check valve 12, and switches the opening / closing switching valve 11 to the communication position and the OP check valve 12 to the check position, so that the master cylinder 1 Normal braking is performed from the communication with the wheel cylinder 2.

Conversely, if it is determined in step 50 that the brake oil pressure control is necessary, the process proceeds to step 52, where it is determined whether or not the brake oil pressure control is a pressure increase control. The pressure is controlled to be adjusted to the required output pressure by the electro-hydraulic control valve 4.

If it is determined in step 52 that the pressure increase control is not performed, the process proceeds to step 54, where the control unit 1
00 transmits a switching control command to the open / close switching valve 11 and the OP check valve 12, and sets the open / close switching valve 11 to the shut-off position, OP
The check valve 12 is switched to the communication position, and the pressure reduction control of the brake hydraulic pressure is performed from the communication between the output port 4 c of the electro-hydraulic control valve and the wheel cylinder 2.

Conversely, if it is determined in step 52 that the pressure increase control is to be performed, the open / close switching valve 11 is set to the shut-off position, and the process proceeds to step 53 where the control unit 100 detects that the OP check valve 12 has been opened. Open / close switch 7
It is determined whether or not the ON signal has been input.

At this time, if the ON signal is input, the routine proceeds to step 54, where the control unit 100 transmits a switching control command to the OP check valve 12, switches the OP check valve 12 to the communicating position, and sets the electro-hydraulic control valve. When the OFF signal is input, the process proceeds to step 51, where a switching control release command is transmitted to the OP check valve 12.

The above command is sent to the control unit 10
0, steps 53 and 54 correspond to delay means for delaying the switching control means.

Finally, an embodiment of the electro-hydraulic control valve 4 will be described in detail with reference to FIG. FIG. 5 shows the configuration of the electro-hydraulic control valve 4, wherein 20 is a spool having the same diameter, 21 is a sleeve, 22 is an oil passage having a cross-sectional area A ₀ penetrating the spool 20, and 23 is inserted into the oil passage 22. A reaction pin in contact with the inner wall 21a of the sleeve 21; 24, a plunger connected to the spool 20; 25, a solenoid;
26 and 27 are springs that support the spool 20.

Next, the operation of the electro-hydraulic control valve 4 will be described. First, a pump pressure is input to the input port 4s, and a solenoid current is supplied to the solenoid 25 based on a command from the control unit 100 shown in FIGS. , The spool 20 is moved via the plunger 24 to the force F in the left direction in the drawing.
receive _s . The spool 20 has springs 26 and 27.
A force F ₁ of the drawings the left direction, the right direction of the drawing force F ₂ exerted by. Further, since the spool 20 has been inserted reaction force pin 23 of the cross-sectional area A _0, the output pressure of the output port 4c P
When is _c, the force balance of the spool 20 based, thus _{F s + F 1 = P c} · A 0 + F 2, P c = (F s + F 1 -F 2) / A 0 where, springs 26 and 27 Is equivalent to
Since the forces F ₁ and F ₂ are almost constant, P _c = F _s / A ₀ (1), and the output pressure P _c changes in proportion to the solenoid thrust F _s .

That is, since the output pressure P _c is proportional to the command value from the control unit 100, the relationship between the output pressure P _c of the electrohydraulic control valve 4 and the command value from the control unit 100 is as follows. FIG. 6 includes the hysteresis.

Therefore, as is apparent from equation (1),
Solenoid thrust F_sSpool 10 on the left
Output pressure P_cIncreases, and
Renoid thrust F_sThe spool 20 moves to the right in the drawing due to the
Output pressure P _cControl to reduce
Is done.

[0071]

According to the present invention, in the vehicle brake control apparatus according to the first aspect of the present invention, in a vehicle running situation where only wheel braking corresponding to the driver's brake operating force is required, the driver's brake operating force is reduced. A brake operation pressure system with a booster that generates a corresponding brake operation pressure communicates with the wheel cylinder, and supplies the brake operation pressure to the wheel cylinder as brake fluid pressure.

Therefore, even when the electronic control pressure system is abnormal, the boosting cannot be disabled, and the braking force does not decrease. In addition, since the electronic control pressure system is not provided with a boost function, there is no need to provide an extra mechanism for the pressure control valve of the electronic control pressure system, and this pressure control valve becomes large. There is no problem.

At this time, in a vehicle running condition in which only the wheel braking corresponding to the driver's brake operating force is required,
Since the electronic control pressure system is not operating including the pressure source, it is possible to prevent the deterioration of energy efficiency caused by constantly controlling the electronic control pressure system.

In a vehicle running condition in which wheel braking control other than braking corresponding to the driver's braking operation force is required, when the output pressure of the electronic control pressure system is to be reduced, the electronic control pressure system is first activated. After that, the switching control means makes the electronic control pressure system communicate with the wheel cylinder, and supplies the output pressure of the electronic control pressure system that has been reduced in pressure as the brake fluid pressure.

Further, when the output pressure of the electronic control pressure system is controlled to increase, first, when the output pressure of the electronic control pressure system becomes higher than the master cylinder pressure, the switching control means is activated. The check means is opened to allow only the liquid flow from the electronic control pressure system to the wheel cylinder by bypassing, and the output pressure of the electronic control pressure system is applied to the wheel cylinder, and then, for example, the opening and closing of the check means The switching control means causes the electronic control pressure system to communicate with the wheel cylinder and supplies the output pressure of the electronic control pressure system as the brake fluid pressure in response to the response from the open / close detection means for detecting the pressure.

Incidentally, at the moment of switching by the switching control means, as is apparent from the above description, when the output pressure of the electronic control pressure system is controlled to be reduced, the brake fluid pressure which occurs at the instant of switching is reduced. In addition, since the pressure reduction control is originally performed, the driver does not have to feel uncomfortable.

When the output pressure of the electronic control pressure system is controlled to increase, the output pressure of the electronic control pressure system is once supplied to the wheel cylinder via the check means to enable smooth switching. Therefore, discomfort given to the driver can be eliminated.

According to a second aspect of the present invention, in the vehicle brake control apparatus, the switching control means supplies a brake operation pressure from the brake operation pressure system to a wheel cylinder as a brake fluid pressure in a normal state. By providing a switching valve for supplying the output pressure from the electronic control pressure system to the wheel cylinder as brake fluid pressure by control, in addition to the above-described operation and effect, the path switching control can be performed in one place, so that the efficiency is improved. Control can be performed.

According to a third aspect of the present invention, in the vehicle brake control apparatus according to the third aspect, the switching control means communicates between the path between the brake operation pressure system and the wheel cylinder in a normal state and shuts off by control. A switching valve, between the path of the electronic control pressure system and the wheel cylinder, when the brake control pressure generated from the electronic control pressure system in a normal state becomes equal to or higher than the brake operation pressure generated from the brake operation pressure system, A check valve that allows only the liquid flow from the electronic control pressure system to the wheel cylinder and communicates by control is provided. In addition to the above-described effects, a path that connects the electronic control pressure system to the wheel cylinder is provided. In addition to the fact that the apparatus is not complicated and large, the two-position switching valve is used, so that the processing accuracy of the switching valve itself is not strict and low. It is possible to reduce the list of.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a first embodiment of a vehicle brake control device according to the present invention.

FIG. 2 is a system diagram showing a second embodiment of the vehicle brake control device according to the present invention.

FIG. 3 is a time chart showing various pressure relationships in the first and second embodiments.

FIG. 4 is a flowchart of a control program according to the first and second embodiments.

FIG. 5 is a configuration diagram showing an embodiment of the electro-hydraulic control valve 4 of FIGS.

FIG. 6 is a diagram showing characteristics of the electro-hydraulic control valve 4 in the same example.

FIG. 7 is a time chart showing various pressure relationships in an example for solving the conventional problem.

FIG. 8 is a time chart showing various pressure relationships in another example for solving the conventional problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Master cylinder 2 Wheel cylinder 3 Pump 4 Electro-hydraulic control valve 5 2 position 3 direction output switching valve 6 Check valve 7 Open / close switch 8 Brake pedal 9 Brake booster 10 Pressure sensor 11 Opening / closing switching valve 12 Electromagnetic operated check valve 20 Spool 21 Sleeve 22 Oil passage 23 Reaction pin 24 Plunger 25 Solenoid 26,27 Spring 100 Control unit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-292556 (JP, A) JP-A-5-221300 (JP, A) JP-A-1-119461 (JP, A) JP-A-62-192461 253556 (JP, A) JP-A-5-270377 (JP, A) JP-A-4-126650 (JP, A) JP-A-63-41272 (JP, A) JP-A-1-3111944 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60T 8/48

Claims (3)

(57) [Claims] 1. A brake operation pressure system with a booster for generating a brake operation pressure corresponding to a driver's brake operation force, and a pressure from an external pressure source as an input and pressure adjustment based on an external command value. An electronic control pressure system for generating the brake control pressure, and a brake hydraulic pressure for the wheel cylinder by selecting one of a brake operation pressure from the brake operation pressure system and a brake control pressure from the electronic control pressure system. A switching valve to be supplied as a control valve; and when the output pressure of the electronic control pressure system is controlled to be reduced, the switching valve bypasses the switching control unit, and a switching control unit that connects the electronic control pressure system to a wheel cylinder. The brake control pressure generated from the electronic control pressure system and the bypass communication passage communicating the electronic control pressure system with the wheel cylinder A vehicle provided with a non-return means for bypassing the switching control means and permitting only a liquid flow from the electronic control pressure system to the wheel cylinder when the pressure becomes equal to or higher than a brake operation pressure generated from the pressure system. Brake control device. 2. The switching control means according to claim 1, wherein the switching control means supplies a brake operation pressure from the brake operation pressure system to a wheel cylinder as a brake fluid pressure in a normal state, and controls the output pressure from the electronic control pressure system. A switching valve for supplying a brake fluid to a wheel cylinder as brake fluid pressure. 3. The switching control means according to claim 1, wherein the switching control means includes an open / close switching valve which is normally communicated between a path between the brake operation pressure system and a wheel cylinder and is shut off by control, and the electronic control pressure system and a wheel. When the brake control pressure generated from the electronic control pressure system in the normal state becomes equal to or higher than the brake operation pressure generated from the brake operation pressure system between the path to the cylinder, the fluid from the electronic control pressure system to the wheel cylinder is increased. A brake control device for a vehicle, comprising: a check valve that allows only flow and communicates by control.