JP2002200973A - Brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To utilize the hydraulic pressure of a master cylinder in a brake device provided with a hydraulic control cylinder to be operated on the basis of the operation of an electric motor. SOLUTION: In the hydraulic control cylinder 12, a rear hydraulic pressure chamber 128 and a pressurization chamber 36 of the master cylinder 10 are directly communicated to each other by a liquid passage 130. A driving force by a control motor 100 and a driving force corresponding to the hydraulic pressure of the rear hydraulic pressure chamber 128 are applied to a control piston 106, and the hydraulic pressure of a control pressure chamber 120 is controlled to a corresponding height. With this structure that the hydraulic pressure of the master cylinder can be utilized, in the case of controlling the hydraulic pressure of the control pressure chamber 120 at a constant value, a current to be supplied to the control motor 100 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a brake device.

[0002]

2. Description of the Related Art An example of a brake device having a hydraulic control cylinder is disclosed in Japanese Patent Application Laid-Open No. 9-511967. This brake device includes (a) a brake cylinder that operates a brake by hydraulic pressure, (b) a master cylinder that generates hydraulic pressure based on operation of a brake operation member by a driver, and (c) operation of a power drive device. A hydraulic pressure control cylinder in which the brake cylinder is connected to a control pressure chamber in front of the control piston, and (d) controlling the power drive device, thereby controlling the brake cylinder. And a brake fluid pressure control device for controlling the fluid pressure.

[0003]

SUMMARY OF THE INVENTION The present invention is an improvement of the above-mentioned brake device, and an object thereof is to enable effective use of energy. This problem is solved by providing the brake device having the following configurations. Each mode is described in the same manner as in the claims, divided into sections, each section is numbered, and described in the form of citing the numbers of other sections as necessary. This is merely for the purpose of facilitating the understanding of the technology described in this specification, and the technical features and their combinations described in this specification should not be construed as being limited to the following sections. Absent. Further, when a plurality of items are described in one section, not all items must always be adopted together, but it is also possible to take out and adopt only some items. (1) a brake cylinder that operates a brake by hydraulic pressure, a master cylinder that generates hydraulic pressure based on an operation of a brake operating member by a driver, and a control piston that is operated based on operation of a power drive device; A hydraulic pressure control cylinder connected to the control pressure chamber in front of the control piston and connected in a state where the master cylinder is always in communication with the rear hydraulic chamber behind, and controlling the power drive device. A brake fluid pressure control device for controlling a fluid pressure of the brake cylinder (claim 1). In the brake device described in this section, the hydraulic pressure of the brake cylinder is controlled by the control of the hydraulic pressure control cylinder.
The master cylinder is connected to the rear hydraulic chamber of the hydraulic control cylinder in a state where the master cylinder is always in communication. Therefore, the hydraulic fluid of the master cylinder can be used for controlling the hydraulic pressure of the brake cylinder. Conventionally, when the hydraulic pressure of the brake cylinder is controlled by the control of the hydraulic pressure control cylinder, the master cylinder is communicated with the stroke simulator, and the hydraulic pressure of the master cylinder is not used for the hydraulic pressure control of the brake cylinder. Did not. On the other hand, in the brake device described in this section, since the brake device is used for controlling the hydraulic pressure of the brake cylinder, the power of the power drive device required for controlling the hydraulic pressure of the brake cylinder can be reduced accordingly. it can. (2) A liquid passage connecting the master cylinder and the control pressure chamber, a communication state provided in the liquid passage for communicating the master cylinder with the control pressure chamber, and a cut-off state for shutting off the master cylinder and the control pressure chamber. Replacement master shut-off valve (1)
The brake device according to claim (claim 2). In the brake device described in this section, a master shutoff valve is provided between the master cylinder and the control pressure chamber. When the master shut-off valve is in the communicating state, the master cylinder and the brake cylinder are communicated via the control pressure chamber. By supplying the master cylinder hydraulic pressure to the brake cylinder,
The brake is actuated. When the master shut-off valve is in the shut-off state, the control pressure chamber is shut off from the master cylinder, and the brake fluid is supplied to the brake cylinder to operate the brake. (3) The brake fluid pressure control device includes a brake operation state detection unit that detects an operation state of the brake operation member, and controls the power drive device based on the brake operation state detected by the brake operation state detection unit. The brake device according to the above mode (1) or (2) for controlling (claim 3). In the brake device described in this section, the power drive device is controlled based on the brake operation state. The brake operation state is acquired by the brake operation state acquisition device. The brake operation state includes an operation force applied to the brake operation member, a brake operation amount such as an operation stroke, and a physical amount having a size corresponding to the brake operation amount. (For example, the master cylinder hydraulic pressure, its equivalent hydraulic pressure,
Deceleration, etc.). Further, the power drive device is controlled based on the brake operation state.However, the power drive device may be controlled according to the brake operation state, or may be controlled according to the change state of the brake operation state. it can. (4) The brake fluid pressure control device controls the power drive device such that the fluid pressure in the control pressure chamber becomes a height based on the brake operation state. A brake device according to one of the preceding claims. In the brake device described in this section, the hydraulic pressure of the control pressure chamber is controlled to a height based on the brake operation state, and the hydraulic pressure of the brake cylinder is controlled to a height based on the brake operation state. Can be. (5) When the power drive device is controlled, the volume of the rear hydraulic chamber is changed in accordance with the operation of the brake operation member, any one of (1) to (4). The brake device according to any one of the above. (6) The method according to any one of (1) to (5), wherein when the power drive device is controlled, the hydraulic pressure in the rear hydraulic chamber is adjusted to a magnitude corresponding to the operating force of the brake operating member. The brake device according to any one of the above. A master cylinder is communicated with the rear hydraulic chamber, and hydraulic fluid is exchanged between the master cylinder and the rear hydraulic chamber. In this case, if the volume of the rear hydraulic chamber is changed with the operation of the brake operating member, and if the hydraulic pressure of the rear hydraulic chamber is set to a hydraulic pressure corresponding to the operating force of the brake operating member, the brake A reaction force corresponding to the operation force can be applied to the operation member.
In this case, the hydraulic control cylinder has the function of a stroke simulator, and a stroke simulator is not required. (7) The master shut-off valve is an electromagnetic shut-off valve that can be switched at least between a communicating state and a shut-off state according to a supply current, and the brake fluid pressure control device switches the electromagnetic shut-off valve to a shut-off state. The hydraulic pressure of the brake cylinder is controlled by controlling the power drive device.
The brake device according to any one of paragraphs (2) to (6). In the brake device described in this mode, the hydraulic pressure in the control pressure chamber is controlled in a state where the master cylinder is disconnected from the control pressure chamber. (8) In the hydraulic pressure control cylinder, the area of the pressure receiving surface on the rear hydraulic pressure chamber side of the control piston is smaller than the area of the pressure receiving surface on the control pressure chamber side. The brake device according to any one of claims (claim 4). In the brake device described in this section, the area of the pressure receiving surface on the rear hydraulic pressure chamber side is smaller than the area of the pressure receiving surface on the control pressure chamber side. The amount of hydraulic fluid supplied to the pressure chamber is smaller. For this reason, it is possible to suppress an increase in the amount of hydraulic fluid flowing out of the master cylinder, and it is easy to reduce the operation stroke of the brake operation member. Since the operation stroke is kept small in a state where the master cylinder is disconnected from the brake cylinder, the same effect as when the master cylinder is connected to the stroke simulator can be obtained without connecting the master cylinder to the stroke simulator. (9) The master cylinder includes a pressurizing piston associated with the brake operating member, the side facing the front pressurizing chamber having a smaller diameter than the portion on the brake operating member side. The brake device according to any one of (1) to (8), wherein the pressure chamber is connected to a rear pressure chamber of the hydraulic pressure control cylinder. The side of the pressurizing piston facing the pressurizing chamber has a smaller diameter than the brake operating member side. Therefore, the hydraulic pressure of the pressurizing chamber when the operating force is the same can be increased as compared with the case where the diameter is not small on the pressurizing chamber side, and the hydraulic pressure of the pressurizing chamber with respect to the operating force can be increased. That is, the boost factor can be increased. When the master cylinder is in communication with the brake cylinder and the operating force is the same, the hydraulic pressure of the brake cylinder can be increased. A decrease in hydraulic pressure can be suppressed. (10) Including a brake cylinder that operates a brake by hydraulic pressure, a master cylinder that generates hydraulic pressure based on operation of a brake operating member by a driver, and a control piston that is activated based on operation of a power drive device, A hydraulic pressure control cylinder in which the brake cylinder is connected to a control pressure chamber in front of a control piston, and the master cylinder is directly connected to a rear hydraulic chamber behind by a liquid passage, and by controlling the power drive device, A brake fluid pressure control device for controlling a fluid pressure of the brake cylinder. In the brake device described in this section, the master cylinder and the rear hydraulic chamber are directly connected by the liquid passage, and a valve device, a stroke simulator, and the like are provided in the middle of the liquid passage connecting these. Absent. In the brake device described in this section,
The technical features described in any of the above modes (1) to (9) can be adopted.

[0004]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a brake device according to an embodiment of the present invention will be described in detail with reference to the drawings.
Reference numeral 10 is a master cylinder, and reference numeral 12 is a hydraulic control cylinder. Reference numerals 14 and 16 denote brake cylinders of brakes 22 and 24 for suppressing rotation of the front wheel 18 and the rear wheel 20, respectively. The brake cylinders 14 and 16 are connected to the master cylinder 10 via the hydraulic control cylinder 12.

[0005] The master cylinder 10 includes pressure pistons 30, 32 provided in a housing 28 in a liquid-tight and slidable manner.
including. The pressurizing piston 30 is linked to a brake pedal 34 as a brake operating member. The pressurizing chamber 36 in front of the pressurizing piston 32 is connected to the brake cylinder 14 of the front wheel 18, and the pressurizing chamber 38 in front of the pressurizing piston 30 is connected to the brake cylinder 16 of the rear wheel 20. The same pressure is generated in the two pressure chambers 36 and 38. The pressure piston 30 has a stepped shape and faces the pressure chamber 38 at the small diameter portion 42. An annular chamber 46 is formed by the step portion of the large diameter portion 44 and the small diameter portion 42 and the housing 28. Small diameter part 4
2 is a communication passage 4 for communicating the annular chamber 46 with the pressurizing chamber 38.
A check valve 50 is provided in the middle of the communication passage 48 to allow the flow of the hydraulic fluid from the annular chamber 46 to the pressurizing chamber 38 and to prevent the flow in the opposite direction.

[0006] A reservoir 62 is connected to the annular chamber 46 via a flow restricting device 60. The working fluid is stored in the reservoir 62 at approximately atmospheric pressure. The flow restricting device 60 allows the flow of the hydraulic fluid in the direction from the reservoir 62 to the annular chamber 46, and prevents the flow in the reverse direction.
And a relief valve 68 that allows the flow of the hydraulic fluid from the annular chamber 46 to the reservoir 62 when the hydraulic pressure in the annular chamber 46 is higher than the hydraulic pressure in the reservoir 62 by a set pressure (relief pressure) or more.
And the orifice 70 are provided in parallel with each other.

As the pressure piston 30 advances (leftward in the figure), the hydraulic pressure in the annular chamber 46 and the pressure chamber 38 is increased.
The hydraulic pressure in the annular chamber 46 is increased until the relief pressure of the relief valve 68 is reached.
8 is higher than the hydraulic pressure of the check valve 5
0, and is supplied to the pressurizing chamber 38 through the brake cylinder 16.
Supplied to In the present embodiment, the relief pressure is set to a height at which the first fill is almost completed. Until the first fill is completed, the hydraulic fluid is supplied from both the annular chamber 46 and the pressurized chamber 38 to the brake cylinder 14,
16 and the first fill can be quickly completed. When the hydraulic pressure in the annular chamber 46 reaches the relief pressure, the hydraulic fluid flows out to the reservoir 62 via the relief valve 68. In this state, the hydraulic pressure in the pressurized chamber 38 is higher than the hydraulic pressure in the annular chamber 46,
The check valve 50 prevents the hydraulic fluid in the pressurizing chamber 38 from flowing into the annular chamber 46. The hydraulic fluid is supplied to the brake cylinders 14 and 16 from the pressurizing chambers 36 and 38 and
No working fluid is supplied from 6. Thus, the flow restricting device 60 can be called a fill-up device.

Thereafter, the hydraulic pressure in the pressurizing chamber 38 is increased as the pressurizing piston 30 advances. In this case, since the liquid pressure in the pressurizing chamber 38 is pressurized by the small diameter portion 42,
As compared with the case where the large-diameter portion 44 is pressurized (the hydraulic pressure of both the annular chamber 46 and the pressurized chamber 38 is pressurized), the brake pedal 3
The hydraulic pressure in the pressurizing chamber 38 when the operating force of 0 is the same increases. The boost factor increases. Since the annular chamber 46 and the reservoir 62 are connected via the orifice 70, when the pressurizing piston 30 is in a steady state, the hydraulic pressure in the annular chamber 46 is substantially at atmospheric pressure. When the pressurizing piston 32 is retracted, the working fluid is supplied from the reservoir 62 via the check valve 66 with the increase in the volume of the annular chamber 46, so that the annular chamber 46 becomes negative pressure. Is avoided.

When the cross-sectional area (pressure receiving area) of the large-diameter portion 44 is Am1 and the cross-sectional area of the small-diameter portion 42 is Am3, the movement of the pressurizing piston 30 when the brake cylinder 16 and the master cylinder 10 are in communication with each other. When the stroke is ΔL, the hydraulic fluid amount q flowing out of the pressurizing chamber 38 is (Am1 · ΔL) before the end of the first fill, and (Am3 · ΔL) after the end of the first fill. (A
m1> Am3). Further, when the increase amount of the hydraulic pressure corresponding to the increase amount of the pedaling force is ΔPF, the hydraulic pressure of the pressurizing chamber 38 becomes
Before the first fill is completed, the increasing gradient ΔPM (=
.DELTA.PF, whereas after the first fill, the increasing gradient .DELTA.PM (= .DELTA.PF.Am1 / Am).
Increased in 3). As described above, before the first fill is completed, the hydraulic fluid can be supplied to the brake cylinder at a large flow rate, and after the first fill is completed, the hydraulic pressure in the pressurizing chamber 38 is increased with a large pressure increase gradient. Can be. In addition, a liquid passage extending from the reservoir 62 is connected to the master cylinder 10 via a pair of cup seals. Further, return springs 72 and 74 are provided between the bottom of the housing 28 and the pressure piston 38 and between the pressure pistons 30 and 32, respectively.

The brake cylinder 14 of the front wheel 18 is connected to the pressurizing chamber 36 by a liquid passage 90, and the brake cylinder 1 of the rear wheel 20 is connected to the pressurizing chamber 38 by a liquid passage 92.
6 is connected. In the middle of the liquid passages 90 and 92, master shut-off valves 94 and 96 as electromagnetic on-off valves are provided, respectively. The opening and closing of the master shutoff valves 94 and 96 causes the brake cylinders 14 and 16 to communicate with the master cylinder 10 or to shut off. Master shut-off valve 94,
Reference numeral 96 denotes a normally-open valve which is open when no current is supplied. In the present embodiment, the master shutoff valves 94 and 96 are switched from the open state to the closed state when the first fill is completed while the electric system is normal. Hydraulic fluid is supplied to the brake cylinders 14 and 16 from the master cylinder 10 at the beginning of the brake operation.
Thereafter, the fluid is supplied from the hydraulic control cylinder 12. Also,
When the electric system is abnormal or the like, it is switched to the open state, and the hydraulic fluid of the master cylinder 10
, The brakes 22 and 24 are operated. Check valves 98 are provided in parallel with the master shutoff valves 94 and 96, respectively. The check valve 98 allows the flow of the hydraulic fluid from the master cylinder side of the master shut-off valves 94 and 96 to the brake cylinder side, and prevents the flow in the reverse direction. The master shut-off valves 94 and 9 are controlled by the check valve 98.
Even if 6 is in the closed state, if the hydraulic pressure on the master cylinder side becomes higher than the hydraulic pressure on the brake cylinder side, the flow of the hydraulic fluid from the master cylinder side to the brake cylinder side is allowed.

The master shutoff valves 94, 9 of the liquid passages 90, 92
A hydraulic control cylinder 12 is provided downstream of 6. The hydraulic control cylinder 12 is operated based on the operation of the control motor 100 which is an electric motor. The control motor 100 is operable in both forward and reverse directions.
2 converts the motion into a linear motion. Exercise conversion device 102
Includes a ball screw mechanism in the present embodiment. Hydraulic pressure control cylinder 12 includes control pistons 106 and 10 provided in housing 104 in a liquid-tight and slidable manner.
8 and so on. An O-ring is provided on the outer peripheral portion of the control piston 106, and is kept liquid-tight. The control piston 106 has a drive shaft 110 as an output shaft of the motion conversion device 102.
Is advanced along with the forward movement of the motor, and is moved forward and backward by the operation of the control motor 100. As shown in the figure, the rotation of the output shaft 111 of the electric motor 100
The rotation is transmitted to the rotation shaft 116 via the pair of gears 112 and 114, and the rotation of the rotation shaft 116 is converted into linear motion by the motion conversion device 102 and output to the drive shaft 110.

The brake cylinders 14 and 16 of the front wheel 18 and the rear wheel 20 are connected to control pressure chambers 120 and 122 in front of the control pistons 106 and 108 (rightward in the figure). The master cylinder 10 and the brake cylinders 14 and 16 are connected via control pressure chambers 120 and 122.

The control pistons 106 and 108 are arranged concentrically and in series with each other. Also, return springs 124 and 126 are provided between the two control pistons 106 and 108 and between the control piston 108 and the housing 104.
Is provided. The control piston 108 is connected to the control pressure chamber 1
The control piston 108 can be referred to as a floating piston in this sense. Also, the control piston 108
The pressure receiving surfaces facing the control pressure chambers 120 and 122 have the same area, and the return springs 124 and 126 have substantially the same urging force. Therefore, the hydraulic pressures of the control pressure chambers 120 and 122 are set to the same height. The hydraulic fluid of the same height is supplied to the brake cylinders 14 and 16 of the front wheel 18 and the rear wheel 20, respectively.
The hydraulic pressure of 16 is increased / decreased in common by the control of the hydraulic pressure control cylinder 12. Control piston 1
08 is slidably fitted to the housing 104 through a seal member 127 in a liquid-tight manner.
Thus, the control pressure chambers 120 and 122 are isolated, and the two systems are independent. Note that the seal member 127 may be provided on the control piston side.

The pressurizing chamber 36 of the master cylinder 10 is connected to a rear hydraulic chamber 128 behind (to the left of the figure) the control piston 106 by a liquid passage 130. Nothing is provided in the middle of the liquid passage 130, and the pressurizing chamber 36 and the rear hydraulic chamber 128 are directly connected. There is always a communication state in which bidirectional flow is allowed. In the present embodiment, the control piston 106 is configured such that the area of the rear pressure receiving surface 132 on the rear hydraulic pressure chamber side is equal to the control pressure receiving surface 1 on the control pressure chamber side.
34 is smaller than the area. As a result, the amount of hydraulic fluid supplied to the brake cylinders 14 and 16 becomes larger than the amount of hydraulic fluid supplied from the master cylinder 10.

When the control pistons 106 and 108 are advanced based on the operation of the control motor 100, the volume of the rear hydraulic chamber 128 is increased accordingly. The hydraulic fluid is supplied to the rear hydraulic chamber 128 from the pressurizing chamber 36 of the master cylinder 10. When the depression force of the brake pedal 34 is reduced, the working fluid in the rear hydraulic chamber 128 is returned to the pressurizing chamber 36 of the master cylinder 10. In the figure, reference numeral 144 denotes a thrust bearing, and reference numeral 146 denotes a radial bearing. These receive axial and radial forces. A flange 148 receives an axial force applied from the control pressure chamber side by the flange 148.

Downstream of the fluid pressure control cylinder 12 in the fluid passages 90 and 92, fluid pressure control valve devices 160 and 160 are provided, respectively.
162 are provided. Hydraulic pressure control valve devices 160, 16
2 include a holding valve 170 and a pressure reducing valve 172, respectively. The holding valve 170 is provided between the hydraulic control cylinder 12 and the brake cylinders 14 and 16, and the pressure reducing valve 172 is
The brake cylinders 14, 16 of the wheels 18, 20 are provided between the brake cylinders 14, 16 and the reservoir 174 by controlling the holding valve 170 and the pressure reducing valve 172.
Are separately controlled. In the present embodiment, the anti-lock control is performed by the control of the hydraulic pressure control valve devices 160 and 162 so that the braking slip state of each wheel becomes an appropriate state with respect to the road surface friction coefficient. Reservoir 1
A pump passage 180 extends from 74, and is connected upstream of the holding valve 170 and downstream of the hydraulic pressure control cylinder 12. In the middle of the pump passage 180,
Pump 182, check valves 184, 186 and damper 18
8 are provided. The pump 182 is a pump motor 19
It is activated by the drive of 0.

The brake device is provided with a brake E shown in FIG.
It is controlled by the CU 200. Brake ECU 200
Includes a control unit 202 mainly composed of a computer and a plurality of drive circuits. The control unit 202 includes a CPU 204, an RO
M206, RAM 208, input / output unit 210, and the like.
The input / output unit 210 includes a brake switch 21 for detecting whether or not the brake pedal 34 is depressed.
1. A treading force sensor 212 for detecting a treading force applied to the brake pedal 34, a master pressure sensor 214 for detecting a hydraulic pressure in the pressurizing chamber 38 of the master cylinder 10, and a hydraulic pressure for the control pressure chamber 120 of the hydraulic control cylinder 12 Control pressure sensor 2
16, a wheel speed sensor 218 for detecting the rotation speed of each wheel 18, 20 and the like are connected. Master pressure sensor 212
Is provided in a liquid passage 92 connected to the pressurizing chamber 38. The control pressure sensor 216 includes the hydraulic pressure control valve device 160,
While the cylinder 62 is in the original position shown in the figure, the brake cylinder 1
The hydraulic pressures of 4 and 16 are detected. The holding valve 170 and the pressure reducing valve 1 are connected to the input / output unit 210 via a drive circuit 226.
72, the coils of the master shutoff valves 94 and 96 are connected, and the pump motor 190, the control motor 100, and the like are connected. Further, the ROM 206 stores various programs and tables such as a normal brake control program shown in the flowchart of FIG. 3 and an antilock control program (not shown in the flowchart).

Next, the operation will be described. When the system is normal, the hydraulic pressure of the brake cylinders 14 and 16 (hereinafter simply referred to as brake hydraulic pressure) in a state where the master cylinder 10 is disconnected from the brake cylinders 14 and 16.
Is controlled by the control of the hydraulic control cylinder 12. The hydraulic control cylinder 12 is controlled based on the operation state of the brake pedal 34. A target value (for example, target brake fluid pressure, target deceleration) is determined based on the brake operation state, and control is performed so that an actual detection value (for example, actual brake fluid pressure, actual front-rear G) approaches the target value. It is. In the present embodiment, control is performed so that the actual brake fluid pressure approaches the target brake fluid pressure as the target value. It should be noted that the actual deceleration is controlled so as to approach the target deceleration as the target value, or is controlled based on the deceleration during traveling, and is controlled based on the brake fluid pressure during the stop. You can also.

When the operation of the brake pedal 34 is released, the current supplied to the coils of the master shut-off valves 94 and 96 is reduced to 0, and is maintained at the original position shown in the figure. The hydraulic fluid in the brake cylinders 14 and 16 is released from the master shut-off valve 9 in the open state.
It is returned to the master cylinder 10 via 4,96. Also,
The hydraulic fluid in the rear hydraulic chamber 128 is returned to the master cylinder 10 via the fluid passage 130.

The power supplied to the control motor 100 is controlled so that the hydraulic pressure in the control pressure chambers 120 and 122 becomes a target brake hydraulic pressure determined according to the pedaling force. Control piston 10
6 includes a driving force F (I) applied by the control motor 100, a hydraulic pressure of the rear hydraulic chamber 128, and a control pressure chamber 120.
Hydraulic pressure acts. Since the hydraulic pressure of the rear hydraulic chamber 128 is the same as the hydraulic pressure PM of the pressurizing chamber 36, the hydraulic pressure PB of the control pressure chamber 120 is PB = (PM · SM + F (I)) / SB. Here, the rear pressure receiving surface 1 of the control piston 106
The area of 32 is SM, and the area of the control-side pressure receiving surface 134 is SB. Further, the master pressure PM is a height corresponding to the pedaling force, and the target value of the control pressure PB is determined to be a height corresponding to a magnitude obtained by multiplying the pedaling force by a constant boost factor. A relationship (PB = k · PM) is established between the pressure and the pressure. If this relationship is substituted into the above equation, the equation PB = (k · F (I)) / (k · SB−SM) is obtained. can get. As shown in this equation, the relationship shown in FIG. 4 is established between the target brake fluid pressure (control pressure PB) and the driving force F (I), and the driving force F ( Current is supplied to obtain I).

The control piston 106 is connected to the control motor 100
The volume of the rear hydraulic chamber 128 is increased or decreased with the movement of the control piston 106. Transfer of the hydraulic fluid is performed between the rear hydraulic chamber 128 and the pressurizing chamber 36. Also, control piston 1
To 06, a driving force F (I) corresponding to the driving torque of the control motor 100 is added. In this case, the relationship between the driving torque output by the control motor 100 and the rotation speed of the control motor 100 is determined by the characteristics of the control motor 100, and the driving force applied to the control piston 106 and the moving speed of the control piston 106 Is determined by the current supplied to the control motor 100, the motion converter 102, the hydraulic control cylinder 12, the control gain, and the like.

Therefore, in the present embodiment, when the supply current to the control motor 100 is controlled based on the brake operation state of the control pressure chambers 120 and 122, the volume of the rear hydraulic chamber 128 is reduced. It changes according to the operation of the brake pedal 34, that is, according to the change in the volume of the pressurizing chamber 36, and the hydraulic pressure in the rear hydraulic chamber 128 changes.
The characteristics of the control motor 100, the structure of the hydraulic pressure control cylinder 12, the specifications of the motion conversion device 102, the control gain, and the like are set so as to have a size corresponding to the operation force of No. 4. The above control mode is an example, and the control of the control motor 100 is not limited to the above mode.

In the flowchart of FIG. 3, in step 1 (hereinafter abbreviated as S1; the same applies to other steps), it is determined whether or not the brake pedal 34 is depressed. When it is depressed, in S2, it is determined whether or not the hydraulic pressure detected by the control pressure sensor 216 has reached the hydraulic pressure at the end of the first fill. Before reaching the first fill end hydraulic pressure, in S3, the master shutoff valves 94 and 96 remain open. Since the hydraulic fluid is supplied to the brake cylinders 14 and 16 at a large flow rate, the first fill can be quickly completed. In this case, since the hydraulic control cylinder 12 is in an inactive state, the pressurizing chamber 36
Is not supplied to the rear hydraulic chamber 128.

When the first fill is completed, in S4, the master shutoff valves 94 and 96 are closed. S5
In, the pedaling force is read by the pedaling force sensor 212, and the target brake fluid pressure is determined accordingly. In S6, the control motor 100 is controlled accordingly. Control pressure chambers 120,
The operating fluid is supplied from 122 and the brakes 18 and 20 are operated. In this case, the control piston 106
Since the area of the pressure receiving surface 132 on the rear hydraulic pressure chamber side is smaller than the pressure receiving surface 134 on the control pressure chamber side, the control pressure chamber 12
The amount of the hydraulic fluid discharged from 0,122 is larger. Therefore, the driver's brake stroke is prevented from being excessive. Further, the volume of the rear hydraulic chamber 128 is changed according to the change in the volume of the pressurizing chamber 36, and the hydraulic pressure of the rear hydraulic chamber 128 is set to a height corresponding to the pedaling force. Thereby, a reaction force can be applied to the brake pedal 34.

On the other hand, when the operation of the brake pedal 34 is released, in S3, as described above,
The master shut-off valves 94 and 96 are returned to their original positions as shown.
Similarly, when an abnormality occurs in the electric system, the electric system is returned to the original position shown in the figure. The master shut-off valves 94 and 96 are opened, and the working fluid in the pressurizing chambers 36 and 38 is directly supplied to the brake cylinders 14 and 16,
The brakes 22, 24 are operated. In this case,
As described above, since the hydraulic pressure in the pressurizing chamber 38 is increased by the small diameter portion 42 of the pressurizing piston 32, a large hydraulic pressure can be generated with respect to the pedaling force.

As described above, in the present embodiment, the same effect as in the case where the stroke simulator is connected to the master cylinder 10 can be obtained by controlling the hydraulic control cylinder 12. During the control, the operation stroke can be suppressed, and when connected to the brake cylinders 14, 16, the hydraulic pressure in the pressurizing chamber 38 can be increased with a large boost factor. In the present embodiment, not only the driving force but also the rear hydraulic chamber 1
A hydraulic pressure of 28 is also applied. Therefore, the rear hydraulic chamber 128
Control pressure chamber 12 compared to the case where no hydraulic pressure is applied
The power supplied to the control motor 100 when the hydraulic pressures of 0 and 122 are controlled to the same height can be reduced. By using the hydraulic pressure of the master cylinder 10, the power consumption of the control motor 100 can be reduced. Further, since a stroke simulator is not required, the number of parts of the brake device can be reduced, and the cost can be reduced.

The brake device can be the device shown in FIG. In the present embodiment, the master cylinder 250 has only one pressurizing piston 252. The pressurizing chamber 254 in front of the pressurizing piston 252 is connected to the control pressure chamber 120 by the liquid passage 90, and the rear hydraulic chamber 128 is connected by the liquid passage 130.
Connected to. The reservoir 62 is connected to the control pressure chamber 122 via a liquid passage 256. This prevents the control pressure chamber 122 from running out of hydraulic fluid. As described above, the present invention is not limited to a tandem type master cylinder having two pressurizing pistons, and can be applied to a master cylinder having one pressurizing piston. The invention consists of [Problems to be solved by the invention,
Problem solving means and effects], and various modifications and improvements by those skilled in the art can be implemented.

[Brief description of the drawings]

FIG. 1 is a circuit diagram (partially sectional view) of a brake device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a brake fluid pressure control device included in the brake device.

FIG. 3 is a flowchart showing a brake control program stored in a ROM of the brake fluid pressure control device.

FIG. 4 is a diagram showing a relationship between a driving force of a control motor in the brake fluid pressure control device and a target brake fluid pressure.

FIG. 5 is a circuit diagram (partially sectional view) of a brake device according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 master cylinder 12 hydraulic control cylinder 14, 16 brake cylinder 100 control motor 128 rear hydraulic chamber 130 liquid passage

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kyoji Mizutani F-term (reference) 3D046 BB01 BB03 BB15 BB28 CC02 DD03 EE01 FF04 HH02 HH16 HH36 LL05 LL23 LL29 LL37 LL46 LL50 MM05 3D048 BB25 BB57 CC54 DD02 HH14 HH15 HH18 HH26 HH37 HH42 HH50 HH66 RR06 RR29 RR35

Claims (4)

[Claims] 1. A brake cylinder for operating a brake by hydraulic pressure, a master cylinder for generating hydraulic pressure based on an operation of a brake operating member by a driver, and a control piston operated based on operation of a power drive device. A hydraulic pressure control cylinder, wherein the brake cylinder is connected to a control pressure chamber in front of a control piston, and the master cylinder is connected to a rear rear pressure chamber in a state of always communicating with the rear pressure chamber; A brake fluid pressure control device for controlling the fluid pressure of the brake cylinder. 2. A liquid passage connecting the master cylinder and the control pressure chamber, a communication state provided in the liquid passage for communicating the master cylinder and the control pressure chamber, and a cut-off state for shutting off the master cylinder and the control pressure chamber. The brake device according to claim 1, further comprising a master shut-off valve that switches to (i). 3. The brake fluid pressure control device includes a brake operation state detection unit that detects an operation state of the brake operation member, and the power drive is performed based on the brake operation state detected by the brake operation state detection unit. The brake device according to claim 1, which controls the device. 4. The hydraulic control cylinder according to claim 1, wherein the area of the pressure receiving surface of the control piston on the rear hydraulic chamber side is smaller than the area of the pressure receiving surface on the control pressure chamber side. 4. The brake device according to any one of 1 to 3.