JP3785804B2 - Braking force control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is, for example, a so-called parallel hybrid vehicle in which an engine and a motor generator are provided side by side, an electric vehicle having only a motor generator as a prime mover, and the like. The present invention relates to a braking force control device for generating and controlling the hydraulic fluid pressure of the above.
[0002]
[Prior art]
An example of such a braking force control device is described in Japanese Patent Application Laid-Open No. 5-176408. This braking force control device is an electric vehicle that uses only a motor generator as a prime mover, but at the time of braking, the motor generator as an electric motor is originally used as a generator, that is, a regenerative operation is performed, and a part of the braking force is used. So-called cooperative control of the working fluid pressure is performed in order to obtain the regenerative torque of the motor generator and to charge the battery with the electric power regenerated by the motor generator. This regenerative cooperative control detects the amount of depression of the brake pedal by, for example, the master cylinder pressure, and subtracts the braking force due to the regenerative torque of the motor generator from the braking force corresponding to the master cylinder pressure. The working fluid pressure is controlled so as to be exhibited by the cylinder for use. When the working fluid pressure is controlled in this way, the master cylinder is disconnected from each brake cylinder, and the working fluid pressure, that is, the master cylinder pressure is absorbed by an accumulator called a stroke simulator. That is, this accumulator is a fluid amount absorbing device for adjusting the feeling of depression of the brake pedal. By the way, as the original pressure of the working fluid pressure to be controlled, for example, a working fluid pressure booster called a booster is used, and this is controlled to a predetermined pressure by a pressure control valve. In addition, when the master cylinder is disconnected from each wheel, in particular, a brake cylinder of a driving wheel driven by a motor generator, that is, when the working fluid pressure from the master cylinder is shut off, a solenoid valve is used.
[0003]
[Problems to be solved by the invention]
However, since the conventional braking force control device uses a unique solenoid valve to shut off the working fluid pressure from the master cylinder, the output system from an individual pressure source such as a working fluid pressure booster is abnormal. When this occurs, there is a possibility that the cutoff of the working fluid pressure from the master cylinder cannot be released, that is, it is not possible to reliably shift to so-called fail-safe compensation.
[0004]
The present invention has been developed in view of these problems, and uses a switching valve that boosts pressure by depressing a brake pedal and uses a working fluid pressure from a pressure source different from the master cylinder as a pilot pressure. Although the working fluid pressure is shut off, the switching valve does not return during braking, so that the braking force that can ensure the transition to fail-safe by bypassing the working fluid pressure until the braking ends. The object is to provide a control device.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the braking force control apparatus according to claim 1 of the present invention is based on a working fluid pressure from the master cylinder and a pressure source that is boosted by depression of the brake pedal and is different from the master cylinder. A braking force control device for switching the working fluid pressure to control the working fluid pressure to the brake cylinder of each wheel, wherein the working fluid pressure from a pressure source different from the master cylinder is used as a pilot pressure and the pilot A switching valve that shuts off the working fluid pressure from the master cylinder when the pressure is equal to or greater than a predetermined value, and a fail-safe valve that shuts off the working fluid pressure from a pressure source different from the master cylinder on the upstream side of the switching valve ; Even if this fail-safe valve shuts off the working fluid pressure from a pressure source different from that of the master cylinder during braking, the braking will end. And a bypass valve for bypassing the hydraulic fluid pressure from the different pressure source with the master cylinder, the abnormality by blocking the working fluid pressure from the different pressure source to the master cylinder in the fail-safe valve, the switching The valve is returned so that the working fluid pressure from the master cylinder can be supplied to the brake cylinder of each wheel. However, if an abnormality occurs during braking, the master valve is used by the bypass valve until braking is terminated. The present invention is characterized in that the braking force is secured by bypassing the working fluid pressure from a pressure source different from that of the cylinder .
[0006]
The present invention mechanically shuts off the working fluid pressure from the master cylinder by using a switching valve that raises the pressure by depressing the brake pedal and uses the working fluid pressure from a pressure source different from that of the master cylinder as a pilot pressure. It is assumed. Therefore, in the event of an abnormality, the working fluid pressure from a pressure source different from that of the master cylinder is shut off by the fail safe valve, so that the switching valve is returned to supply the working fluid pressure from the master cylinder to the braking cylinder of each wheel. In addition, the working fluid pressure control system from a pressure source different from that of the master cylinder can be stopped. However, if an abnormality occurs during braking, the fail-safe valve shuts off the working fluid pressure from a pressure source different from that of the master cylinder, so that the pilot pressure to the switching valve is sealed and cannot be returned. Therefore, even if an abnormality occurs during braking, the bypass valve bypasses the working fluid pressure from a pressure source different from that of the master cylinder to ensure the braking force until the braking is finished. Fail safe can be performed.
[0007]
According to a second aspect of the present invention, the braking force control apparatus according to the second aspect of the present invention is the invention according to the first aspect, wherein the bypass valve is opened when the downstream pressure of the fail-safe valve is a pilot pressure and the pilot pressure is high. It is a normally closed switching pilot valve that is in a state.
[0008]
According to a third aspect of the present invention, the braking force control apparatus according to the third aspect is characterized in that, in the first or second aspect, the individual pressure source is a working fluid pressure boost apparatus.
[0009]
【The invention's effect】
Thus, according to the braking force control apparatus according to claim 1 of the present invention, the switching valve that increases the pressure by depressing the brake pedal and uses the working fluid pressure from a pressure source different from the master cylinder as the pilot pressure, When the brake pedal is depressed, that is, when braking, the working fluid pressure is mechanically cut off from the master cylinder, but when there is an abnormality, the working fluid pressure from a pressure source different from that of the master cylinder is cut off by the fail-safe valve. The working fluid pressure from the master cylinder can be supplied to the braking cylinder of each wheel, and the control system for the working fluid pressure from a pressure source different from that of the master cylinder stops functioning. Even if this occurs, the working fluid pressure from a pressure source different from that of the master cylinder is controlled by the bypass valve until the braking is completed. By securing the braking force to pass, it is possible to reliably transition to the fail-safe under all circumstances.
[0010]
According to the braking force control apparatus of the second aspect of the present invention, the bypass valve is a normally closed switching pilot valve that is opened when the downstream pressure of the fail-safe valve is a pilot pressure and the pilot pressure is high. Even if the fail-safe valve shuts off the working fluid pressure from a pressure source different from that of the master cylinder in the event of an abnormality during braking, the bypass valve is operated with the working fluid pressure sealed downstream from the fail-safe valve. Can be kept open to bypass working fluid pressure from a different pressure source than the master cylinder.
[0011]
Further, according to the braking force control apparatus according to claim 3 of the present invention, it is not necessary to provide a new working fluid pressure source by using the working fluid pressure boost device as a pressure source separate from the master cylinder, The structure can be simplified.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the braking force control apparatus of the present invention will be described with reference to the accompanying drawings.
[0013]
FIG. 1 is an example in which the braking force control device of the present invention is developed as a braking force control device for a so-called FF type parallel hybrid vehicle. This braking force control system is a four-wheel integrated control actuator unit 5 that controls the pressure increase / decrease by separating the working fluid pressure from all four wheels from the master cylinder, ensuring the braking distance and steering. An anti-lock brake control actuator unit 6 for achieving both effects and a front wheel control actuator unit 7 for controlling only the working fluid pressure to the front wheel mainly in the pressure reducing direction are configured. Of course, all the actuator units may be combined in one housing.
[0014]
In the figure, 1FL and 1FR are wheel cylinders as brake cylinders for the front left and right wheels, respectively, 1RL and 1RR are wheel cylinders as brake cylinders for the rear left and right wheels, respectively, and the master cylinder 2 determines the amount of depression of the brake pedal 3. The corresponding working fluid pressure can be output to two systems, basically the front left wheel cylinder (hereinafter also simply referred to as front left wheel cylinder) 1FL and the rear right wheel cylinder (rear right wheel cylinder). 1RR is connected to one system of the master cylinder 2, and the front right wheel wheel cylinder (front right wheel cylinder) 1FR and the rear left wheel wheel cylinder (rear left wheel cylinder) 1RL are connected to the other system of the master cylinder 2. They are connected to form a so-called X piping format. In addition, although the booster 4 is interposed between the brake pedal 3 and the master cylinder 2, the detail of the structure etc. is mentioned later.
[0015]
Here, in order to facilitate understanding, the structure of each wheel cylinder 1FL to 1RR side from the structure of the antilock brake control actuator unit 6 will be described. The pressure control valve structure in the anti-lock brake control actuator unit 6 is the same as that of the conventional recirculation type. For example, one system from the master cylinder 2 is branched into two and the other system The wheel cylinders 1FL to 1RR are connected to the respective branch destinations via anti-lock brake control pressure increase control valves 51FL to 51RR. These pressure increase control valves 51FL to 51RR are normally open two-position switching solenoid valves. Note that check valves 52FL to 52RR that allow only the return of the working fluid from the wheel cylinders 1FL to 1RR to the master cylinder 2 side are bypass-connected to the pressure increase control valves 51FL to 51RR.
[0016]
Further, pressure-reducing control valves 53FL to 53RR for anti-lock brake control comprising normally closed two-position switching solenoid valves are connected to the downstream side of the pressure-increasing control valves 51FL to 51RR for anti-lock brake control, and the output side thereof is connected. For each system, a common reservoir 54P, 54S and a pump 55P, 55S are branched and connected, and the discharge side of each pump 55P, 55S is connected to each system of the master cylinder 2 via dampers 56P, 56S.
[0017]
The actuator unit 6 for antilock brake control is controlled according to antilock brake control calculation processing executed in a brake control unit (not shown) based on a wheel speed signal from a wheel speed sensor. That is, the relationship between each wheel speed and the vehicle body speed is monitored. For example, when the slip ratio is equal to or greater than a predetermined value and each wheel is likely to lock, the pressure increase control valves 51FL to 51RR and the pressure decrease control valves 53FL to 53RR are detected. Is operated, and the working fluid pressure is controlled to be reduced, maintained and increased to prevent the wheel from being locked.
[0018]
In the present embodiment, the front wheel control actuator unit 7 is interposed between the downstream sides of the front left and right wheel antilock brake control pressure increase control valves 51FL and 51FR and the front left and right wheel cylinders 1FL and 1FR. Yes. The front wheel control actuator unit 7 has two normally open positions interposed between the downstream sides of the front left and right wheel antilock brake control pressure increase control valves 51FL and 51FR and the front left and right wheel cylinders 1FL and 1FR. Front left and right wheel pressure reduction control switching valves 41FL and 41FR composed of switching solenoid valves, and check valves 42FL and 42FR which are bypassed to allow only recirculation from the front left and right wheel cylinders 1FL and 1FR to the master cylinder 2 side, Further, it is composed of proportioning valves 43FL and 43FR which are bypass-connected to the front left and right wheel cylinders 1FL and 1FR and can substantially reduce the working fluid pressure. Incidentally, when the output pressure of the proportioning valves 43FL and 43FR is relatively low with respect to the input pressure on the master cylinder 2 side, for example, the output pressure gradually increases with a pressure increase gradient smaller than the pressure increase gradient of the input pressure. When the input pressure becomes equal to or higher than a predetermined value, a pressure that increases with the same pressure increase gradient as that of the input pressure is applied.
[0019]
The front wheel control actuator unit 7 is controlled in accordance with a front left / right wheel pressure reduction control calculation process executed in the brake control unit (not shown). That is, when the motor generator is regeneratively operated, the front left and right wheel pressure reduction control switching valves 41FL and 41FR are closed, and the working fluid pressures of the front left and right wheel cylinders 1FL and 1FR are adjusted by the proportioning valves 43FL and 43FR. The pressure is controlled to be lower than the supply pressure on the side. That is, the vehicle of the present embodiment is an FF type, and both the engine and the motor generator are connected only to the front wheels. Therefore, since the regenerative torque by the motor generator is also applied only to the front wheels, it is necessary to reduce the working fluid pressure of the front left and right wheel cylinders 1FL, 1FR by the amount of braking force due to this regenerative torque. In other words, if the regenerative torque from the motor generator is applied only to the front wheels, the braking force on the front wheels will be greater than that on the rear wheels simply by reducing the working fluid pressure of all the wheel cylinders. Thus, there arises a problem that, for example, antilock brake control is started early. Therefore, in the present embodiment, the working fluid pressures of the front left and right wheel cylinders 1FL and 1FR are reduced by the proportioning valves 43FL and 43FR by the amount of the braking force due to the regenerative torque.
[0020]
Next, the booster 4 and the working fluid pressure source to the booster 4 will be described before the four-wheel integrated control actuator unit 5. In the hybrid vehicle as in the present embodiment, the engine may be stopped, so the electric pump 11 is used as the working fluid pressure source to the booster 4. The electric pump 11 sucks the working fluid in the main reservoir 8 and passes it through the check valve 12 for discharge. The accumulator 13 is connected to the discharge side of the electric pump 11 and further connected to the input side of the booster 4. Pressure switches 14 and 15 are disposed on the upstream side and the downstream side of the accumulator 13 so that the electric pump 11 operates regardless of which is lower, so that the working fluid pressure in the accumulator 13 is reduced. That is, the supply fluid pressure to the booster 4 can be maintained at a predetermined value or higher.
[0021]
The basic structure of the booster 4 is the same as the existing one. That is, as shown in FIG. 2 (the figure shows a state where the brake pedal 3 is depressed), when the brake pedal 3 is not depressed, the input shaft 71 is retracted to the right in the drawing, and as a result, the steel ball 72 is Since the spring 74 is pressed against the valve seat 73, the working fluid pressure from the accumulator 13 taken from the outer periphery of the piston 75 cannot flow into the cylinder chamber 76 inside the piston 75 and presses the piston 75. No force is generated. The cylinder chamber 76 also communicates with the inside of the booster body 70. A rod 77 connected to the master cylinder 2 extends from the piston 75. Reference numerals 78 and 79 in the figure denote return springs for retracting the piston 75 and the rod 77 to the right in the figure in a state where the brake pedal 3 is not depressed.
[0022]
When the brake pedal 3 is depressed from this state, the input shaft 71 is moved to the left in the figure against the elastic force of the spring 80 interposed between the valve seat 73 and the tip of the input shaft 71 is spring 74. The steel ball 72 is moved together with the holder 82 to the left in the figure against the elastic force, and the steel ball 72 is separated from the valve seat 73. Then, the working fluid pressure from the accumulator 13 flows into the cylinder chamber 76 in the piston 75 through the port 81 formed in the input shaft 71 from the gap between the input shaft 71 and the valve seat 73. Since the piston 75 is pressed together with the valve seat 73 to the left in the figure, the rod 77 is moved to the master cylinder 2 side and the working fluid pressure in the master cylinder 2 is increased. Of course, after this, the piston 75 together with the valve seat 73 may also be pushed to the left by the input shaft 71. However, since the piston is always pushed by the working fluid pressure first, the pedaling force of the brake pedal 3 is Even if it is small, a large driving force can be obtained, whereby the working fluid pressure in the master cylinder 2 is doubled (boosted).
[0023]
Next, when the depression of the brake pedal 3 is stopped in a state where the brake pedal 3 is depressed to some extent, the valve seat 73 and the input shaft 71 are separated from each other by the elastic force of the spring 80. On the other hand, the input shaft 71 is relatively retracted to the right in the drawing (however, the input shaft 71 is in contact with the steel ball 72), whereby the steel ball 72 is again brought into contact with the valve seat 73 by the elastic force of the spring 74. Since the pressure is pressed, the gap between the two is closed and the working fluid pressure in the cylinder chamber 76 is sealed, and an auxiliary force for maintaining the piston 75 and the rod 77 in the state of moving to the master cylinder 2 side by the sealed pressure is obtained. .
[0024]
On the other hand, when the foot is released from the brake pedal 3 from such a state, the free input shaft 71 is further retracted to the right in the figure by the spring 80, and the steel ball 72 remains in contact with the valve seat 73 while being in contact with the valve seat 73. And the input shaft 71 are separated from each other. Then, the working fluid pressure in the cylinder chamber 75 flows from the gap between the input shaft 71 and the valve seat 73 to the flow path 83 and the input shaft guide 84 formed from the tip of the input shaft 71. It flows back to the main reservoir 8 through the passages 85 and 86 and the flow passage 87 formed in the booster body 70.
[0025]
As described above, in the booster 4 of the present embodiment, the working fluid pressure from the accumulator 13 flows into the cylinder chamber 76 and is constantly increased from the start of the depression of the brake pedal 3. Therefore, in the present embodiment, the working fluid pressure in the cylinder chamber 76 is increased with the depression of the brake pedal 3 and is a flow for taking out the working fluid pressure from a fluid pressure source different from the working fluid pressure of the master cylinder 2. A path 88 was formed in the valve body 70. The working fluid pressure taken out from here is taken into an after-mentioned four-wheel integrated control actuator unit 5 and used for braking force control during regeneration.
[0026]
Next, the overall configuration of the four-wheel integrated control actuator unit 5 will be described. First, regenerative switching valves 21P and 21S comprising two-position switching pilot valves using the working fluid pressure taken out from the booster 4 as a pilot pressure are interposed in each system of the two working fluid pressures from the master cylinder 2. ing. The P ports of the regenerative switching valves 21P and 21S comprising the two-position switching pilot valves are connected to the output side of each system of the master cylinder 2, and the A port is also connected to the anti-lock brake control pressure increase control valves 51FL to 51RR. The B port is branched, and the B port is connected to stroke simulators 22P and 22S formed of a kind of accumulator. The regenerative switching valves 21P and 21S allow the P port and the A port to communicate with each other in a normal state without a pilot pressure, and allow only recirculation from the B port to the P port and the A port by the check valves 20P and 20S. To do. Moreover, in the switching state by pilot pressure, A port is interrupted | blocked and P port and B port are connected. Incidentally, the return springs of the stroke simulators 22P and 22S have spring constants equivalent to the working fluid pressure reaction force generated in the booster 4 and the master cylinder 2, and the surplus working fluid is used as the main reservoir 8 Reduced to Further, pressure sensors 23P and 23S and pressure sensors 24P and 24S are provided on the upstream side and the downstream side of the regenerative switching valves 21P and 21S, respectively.
[0027]
On the other hand, the working fluid pressure extraction system of the booster 4 is branched and supplied as pilot pressures of the regenerative switching valves 21P and 21S via a fail-safe valve 25 comprising a normally closed electromagnetic two-position switching valve. In addition, a check valve 26 that allows only recirculation to the booster 4 side and a bypass valve 27 that is a normally closed two-position switching pilot valve are bypass-connected to the fail-safe valve 25 in parallel. The pilot pressure is the downstream pressure of the fail-safe valve 25 (or the downstream pressure of the bypass valve 27 itself). Thus, in principle, when the fail safe valve 25 is opened, the downstream pressure, that is, the pilot pressure of the bypass valve 27 increases, so that the bypass valve 27 is also opened and the working fluid pressure from the booster 4 is low. When the fail-safe valve 25 is closed, the downstream pressure, that is, the pilot pressure of the bypass valve 27 is reduced, so that the bypass valve 27 is also closed.
[0028]
Further, an orifice 28 is interposed between the fail-safe valve 25 and each of the regenerative switching valves 21P and 21S, and only the inflow to the regenerative switching valves 21P and 21S (its pilot pressure) is permitted to the orifice 28. The check valve 29 is bypassed. In the drawing, these orifices 28 and check valves 29 are provided one by one on the upstream side of the branch, but one each on the downstream side of the branch, that is, for each regenerative switching valve 21P, 21S. You may make it interpose.
[0029]
Further, on the downstream side of the fail-safe valve 25 or the downstream side of the bypass valve 27, a four-wheel integrated control pressure-increasing control valve 30 comprising a normally open two-position switching solenoid valve, and a normally closed two-position switching solenoid valve. The four-wheel integrated control decompression control valve 31 and the four-wheel integrated control reservoir 32 are connected in series, and the return of the reservoir 32 is returned to the main reservoir 8. The four-wheel integrated control pressure-increasing control valve 30 and the four-wheel integrated control pressure-reducing control valve 31 are connected to the input port of the pressure control cylinder 16. The four-wheel integrated control pressure increase control valve 30 includes a check valve 33 that allows only recirculation from the pressure control cylinder 16, and a working fluid pressure upstream of the pressure increase control valve 30 above a predetermined pressure. A relief valve 34 for relief is bypassed in parallel. Further, a check valve 35 that allows only reflux from the four-wheel integrated control reservoir 32 is bypass-connected to the four-wheel integrated control decompression control valve 31. Further, a pressure sensor 36 for detecting the input working fluid pressure of the pressure control cylinder 16 may be attached as necessary.
[0030]
The pressure control cylinder 16 has cylinder portions 18P and 18S having pistons 17P and 17S having the same shape, that is, at least the pressure receiving area on the input side and the pressure receiving area on the output side facing each other in one cylinder body. The output ports of the cylinder portions 18P and 18S are connected to the systems from the master cylinder 2 on the downstream side of the regeneration switching valves 21P and 21S, respectively. Of course, the return springs 19P and 19S of the cylinder portions 18P and 18S are of the same specification including the spring constant. That is, the same working fluid pressure can be output from the two cylinder portions 18P and 18S to the two systems from the master cylinder 2 with respect to the input working fluid pressure. Further, the so-called pressure receiving area ratio between the pressure receiving area on the input side and the pressure receiving area on the output side of each of the pistons 17P and 17S is equal to the ratio between the output pressure of the master cylinder 2 and the working fluid pressure taken out from the booster 4. It almost agrees.
[0031]
The details of the bypass valve 27 will be described with reference to FIG. The bypass valve 27 is of a type in which the poppet 62 is driven by a piston 61. As shown in the upper half of FIG. 3, the bypass valve 27 is a working fluid pressure from the downstream of the failsafe valve 25 to the pilot port 64, that is, a pilot. When there is no pressure, the piston 61 is moved to the right by the return spring 65, and the poppet 62 is also moved to the right by the return spring 66. Accordingly, the tapered portion of the poppet 62 is formed in the valve body 63. The input port 67 connected to the booster 4 in contact with the seat portion 69 and the control port 68 connected to the pressure control cylinder 16 are shut off, and the working fluid pressure from the booster 4 is controlled by the four-wheel control. The pressure increase control valve 30 for control, the pressure reduction control valve 31 and the pressure control cylinder 16 are not supplied. No.
[0032]
On the other hand, when the downstream pressure of the fail-safe valve 25 is high, the working fluid pressure in that portion becomes the pilot pressure from the pilot port 64 and moves the piston 61 to the left in the drawing, and the poppet 62 is also moved to the left in the drawing. Then, the tapered portion of the poppet 62 is separated from the seat portion 69 of the valve body 63, and the input port 67 connected to the booster 4 and the control port 68 connected to the pressure control cylinder 16 are connected to the cylinder and the rod portion. 69, the working fluid pressure from the booster 4 is supplied to the pressure control cylinder 16 via the four-wheel integrated control pressure increase control valve 30 and the pressure reduction control valve 31. .
[0033]
The four-wheel integrated control actuator unit 5 is controlled according to the four-wheel integrated control calculation process executed in the brake control unit (not shown). That is, when no abnormality is detected as a braking force control device, the fail-safe valve 25 is opened, and when the brake pedal 3 is depressed without the anti-lock brake control being performed, the brake pedal 3 is removed from the booster 4. Since the working fluid pressure is increased, the bypass valve 27 whose pilot pressure is the downstream pressure of the fail-safe valve 25 is also switched and opened. Further, since the downstream pressure of the fail safe valve 25 is supplied as a pilot pressure to the regeneration switching valves 21P and 21S through the check valve 29, the regeneration switching valves 21P and 21S are switched to the downstream side. The side, that is, the wheel cylinders 1FL to 1RR side is cut off, and each system of the master cylinder 2 is connected to the stroke simulators 22P and 22S. Therefore, the working fluid pressure of each system of the master cylinder 2 operates the pistons in the stroke simulators 22P and 22S, but the return spring generates a reaction force equivalent to the reaction force in the master cylinder 2 or the booster 4. The driver does not feel uncomfortable with the depression of the brake pedal 3.
[0034]
On the other hand, for example, the regenerative torque by the motor generator can be obtained from the vehicle speed, the gear ratio, etc., so that the braking force of the front left and right wheels is calculated and the working fluid detected by the pressure sensors 23P and 23S on the master cylinder side. The braking force when the working fluid pressure is supplied to the wheel cylinders 1FL to 1RR is calculated from the pressure, and the braking force comprising the difference between the two and the working fluid pressure detected by the pressure sensors 24P and 24S on the wheel cylinder side are calculated. The output pressure from the pressure control cylinder 16 is controlled so that the braking force corresponding to Here, since the pressure control cylinder 16 can supply the same working fluid pressure to the two systems connected to the X pipe, the pressure control cylinder 16 can be used to control the pressure increase / decrease in the same manner. What is necessary is just to carry out pressure increase / decrease control to the input pressure to. At this time, since the ratio between the output pressure and the input pressure of the pressure control cylinder 16 is an inverse ratio of the pressure receiving area ratio of the pistons 17P and 17S of the two cylinder portions 18P and 18S, the required working fluid pressure, An increase / decrease amount of the input pressure with respect to the increase / decrease amount of the output pressure is set. Then, the four-wheel integrated control pressure-increasing control valve 30 and the four-wheel integrated control pressure-reducing valve 31 may be controlled to open and close in accordance with the amount of increase or decrease in the input pressure. As the pressure increase / decrease control of the input pressure to the pressure control cylinder 16, for example, a conventional PWM (Pulse Width Modulation) control based on an existing duty ratio can be applied, and a detailed description thereof will be omitted. The working fluid pressure corresponding to the pressure reduced by the four-wheel integrated control pressure reducing valve 31 is stored in the four-wheel integrated control reservoir 32 in principle.
[0035]
Further, for example, when the regenerative switching valve is solenoid driven, an electric structure for driving the solenoid is required, and if the regenerative operation time due to depression of the brake pedal 3 as described above becomes long, for example, There is a problem that the excitation time of the solenoid becomes longer and the amount of heat generation increases or the energy loss increases. In this embodiment, in order to drive the regenerative switching valves 21P and 21S, Since the working fluid pressure in the booster 4 that is constantly generated during the stepping-in is used as the pilot pressure, the structure is simplified and an excessive amount of heat generation and energy loss can be suppressed and prevented.
[0036]
Further, even when the brake pedal 3 is being depressed during such regenerative operation, even if the brake pedal 3 is slightly returned and the working fluid pressure taken out from the booster 4 is to be reduced, the regenerative switching valves 21P and 21S are returned. Since the pilot pressure is reduced only slowly through the orifice 28, it is possible to prevent the regeneration switching valves 21P and 21S from erroneously returning to the normal position and to continue the regeneration cooperative control. On the other hand, when the brake pedal 3 is depressed, the working fluid pressure taken out from the booster 4 flows as the pilot pressure of the regenerative switching valves 21P and 21 from the check valve 29 side without passing through the orifice 28, so that necessary responsiveness is ensured. can do.
[0037]
Further, when the foot is released from the brake pedal 3 from this state, the working fluid pressure taken out from the booster 4 is also reduced as described above, so that the pilot pressure of the regenerative switching valves 21P and 21S also passes through the orifice 28. The pressure is slowly reduced, the regeneration switching valves 21P and 21S return to the normal position, and the master cylinder 2 is again connected to the wheel cylinders 1FL to 1RR. The working fluid in the four-wheel integrated control reservoir 32 passes through the check valve 35 and returns to the booster 4 through the check valve 33 and the check valve 26 together with the working fluid in the pressure control cylinder 16.
[0038]
Incidentally, when the anti-lock brake control is to be started while the brake pedal 3 is depressed, the regenerative operation is stopped, and the regenerative cooperative control of the braking force is also stopped.
[0039]
If an abnormality is detected when the brake pedal 3 is not depressed, if the fail-safe valve 25 is closed, the bypass valve 27 is also kept closed even if the brake pedal 3 is depressed next. Therefore, the working fluid pressure in the booster 4 is not supplied downstream, and the regenerative switching valves 21P and 21S maintain the master cylinder 2 and the wheel cylinders 1FL to 1RR in communication with each other, thereby obtaining a fail-safe function.
[0040]
On the other hand, if an abnormality is detected with the brake pedal 3 depressed, the fail-safe valve 25 is immediately closed as described above. However, even if the fail-safe valve 25 is closed at this time, the downstream pressure of the fail-safe valve 25, that is, the working fluid pressure on the booster 4 side of the check valve 26 is high, so the pilot pressures of the regenerative switching valves 21P and 21S are enclosed. Accordingly, the regenerative switching valves 21P and 21S remain disconnected from the working fluid system from the master cylinder 2 without being depressurized. However, at this time, the enclosed pilot pressure of the regenerative switching valves 21P and 21S, that is, the downstream pressure of the failsafe valve 25 acts as the pilot pressure of the bypass valve 27, so that the bypass valve 27 is maintained in the open state. Accordingly, as a similar fail-safe measure, the four-wheel integrated pressure increase control valve 30 is maintained in the open state and the four-wheel integrated pressure increase control valve 31 is maintained in the closed state. Since the two systems continue to be supplied through the control cylinder 16, braking by the working fluid pressure can be maintained at least until the foot is released from the brake pedal 3. The pressure receiving area ratio of the pistons 17P and 17S of the two cylinder portions 18P and 18S of the pressure control cylinder 16 is set to the ratio of the output pressure of the master cylinder 2 and the working fluid pressure taken out from the booster 4. The working fluid pressure from the pressure control cylinder 16 obtained sometimes becomes equivalent to that from the master cylinder 2, stabilizes the braking force, and does not cause a sense of incongruity.
[0041]
In addition, the pressure receiving area ratio of the pistons 17P and 17S of the two cylinder portions 18P and 18S of the pressure control cylinder 16 is set to the ratio of the output pressure of the master cylinder 2 and the working fluid pressure taken out from the booster 4. As a result, the working fluid pressure from the pressure control cylinder 16 becomes equivalent to that from the master cylinder 2, so that the control mode downstream of the antilock brake control actuator unit is different from that for the working fluid pressure from the master cylinder 2. It can be shared for easy control.
[0042]
In the above embodiment, the case where the antilock brake control actuator unit and the front wheel pressure reduction control actuator unit are provided has been described. However, these may be set as necessary.
[Brief description of the drawings]
FIG. 1 is a hydraulic circuit diagram showing an embodiment of a braking force control apparatus of the present invention.
FIG. 2 is an explanatory diagram of the booster of FIG.
FIG. 3 is an explanatory diagram of the bypass valve of FIG. 1;
[Explanation of symbols]
1FL to 1RR are wheel cylinders (braking cylinders)
2 is a master cylinder 3 is a brake pedal 4 is a booster 5 is a four-wheel overall control actuator unit 6 is an anti-lock brake control actuator unit 7 is a front wheel control actuator unit 8 is a reservoir 11 is an electric pump 12 is a check valve 13 is an accumulator 14 is a pressure switch 15 is a pressure switch 16 is a pressure control cylinder 17P, 17S is a piston 18P, 18S is a cylinder portion 19P, 19S is a return spring 20P, 20S is a check valve 21P, 21S is a regenerative switching valve 22P, 22S is a stroke simulator 23P , 23S is a pressure sensor 24P, 24S is a pressure sensor 25, a fail-safe valve 26 is a check valve 27, a bypass valve 28 is an orifice 29, and a check valve 30 is a four-wheel integrated control booster. The control valve 31 is a four-wheel integrated control decompression control valve 32 is a four-wheel integrated control reservoir 33 is a check valve 34 is a relief valve 35 is a check valve 41FL, and 41FR is a front left and right wheel decompression control switching valve 42FL and 42FR is a check valve. 43FL and 43FR are proportioning valves

Claims (3)

Braking force for controlling the working fluid pressure to the braking cylinder of each wheel by switching the working fluid pressure from the master cylinder and the working fluid pressure from a pressure source different from the master cylinder that is boosted by depressing the brake pedal A control valve that uses a working fluid pressure from a pressure source different from the master cylinder as a pilot pressure and shuts off the working fluid pressure from the master cylinder when the pilot pressure is equal to or higher than a predetermined value; A fail-safe valve that shuts off working fluid pressure from a pressure source different from the cylinder upstream of the switching valve, and this fail-safe valve shuts off working fluid pressure from a pressure source different from the master cylinder during braking. However, a bypass that bypasses the working fluid pressure from a pressure source different from that of the master cylinder until the braking is completed. And a valve, the abnormality by blocking the working fluid pressure from the different pressure source to the master cylinder in the fail-safe valve, braking of each wheel of the hydraulic fluid pressure from the master cylinder to return the switching valve If an abnormality occurs during braking, the bypass valve bypasses the working fluid pressure from a pressure source different from that of the master cylinder until the braking is completed. A braking force control device characterized by securing 2. The braking force control according to claim 1, wherein the bypass valve is a normally closed switching pilot valve that is opened when the downstream pressure of the fail-safe valve is a pilot pressure and the pilot pressure is high. apparatus. The braking force control device according to claim 1, wherein the individual pressure source is a working fluid pressure boost device.

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