JP2611533B2 - Automotive brake system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automotive brake system including both a master cylinder that mechanically generates hydraulic pressure and an electric control hydraulic pressure source that generates hydraulic pressure by electric control. In particular, it is possible to electrically control the correspondence between the operation force or operation stroke of the brake operation member and the brake fluid pressure generated in the wheel cylinder, and also to prevent trouble in the electric control system even when the electric control system fails. The present invention relates to a brake system capable of braking.

2. Description of the Related Art In a manual brake system in which a brake hydraulic pressure is generated only by a master cylinder, a brake hydraulic pressure generated in a wheel cylinder, that is, a brake braking force is uniquely determined based on an operating force of a brake operating member. However, there are cases where it is desired to freely change the correspondence between the brake operation pressure and the brake operation amount, which is the operation force or operation stroke of the brake operation member. For example, the deceleration generated in the vehicle body during braking is not uniquely determined by the brake fluid pressure, that is, the braking force, but is affected by the friction coefficient of the brake friction material, the loaded weight of the vehicle, and the gradient of the road surface. This is a case in which a vehicle deceleration having a magnitude corresponding to the brake operation amount is always obtained without being affected by the above.

The applicant has previously developed the following brake system in order to satisfy the desire to always obtain a vehicle deceleration of a magnitude corresponding to the brake operation amount. This is a manual / electric dual system brake system described in Japanese Patent Application Laid-Open No. 63-20256, in which (a) a master cylinder that generates a brake fluid pressure based on the operating force of a brake operating member; b) an electric control hydraulic pressure source for generating a brake hydraulic pressure at a height that causes a vehicle deceleration having a predetermined magnitude corresponding to the brake operation amount by electric control; (c) their master cylinders; A switching device that connects the electric control hydraulic pressure source to the wheel cylinder. When the electric control hydraulic pressure source operates normally, the wheel cylinder is disconnected from the master cylinder and communicates with the electric control hydraulic pressure source. (D) shut off from the electric control hydraulic pressure source and communicate with the master cylinder
(E) a liquid absorber which is connected via a sub-liquid passage to a main liquid passage connecting the master cylinder to the switching device, temporarily stores brake fluid discharged from the master cylinder, and returns to the master cylinder when the brake is released; An electromagnetic on-off valve is connected in the middle of the auxiliary liquid passage and opens when the electric control hydraulic pressure source operates normally and closes when the electric control hydraulic pressure source fails.

In this brake system, when the electric control fluid pressure source operates normally, the master cylinder does not directly participate in the generation of brake fluid pressure, and it is not essential to discharge the brake fluid from the master cylinder. It is possible to omit valves and liquid absorbers. But,
In such a case, even if the operating force is changed, the operation stroke changes only slightly, so that the brake operation feeling becomes considerably hard. Therefore, in this brake system, by adding the solenoid on-off valve and the liquid absorber, an appropriate amount of brake fluid is discharged from the master cylinder even when the electric control hydraulic pressure source is operating normally, and an appropriate amount is This makes it possible to obtain a great operation stalk.

Problems to be Solved by the Invention By using the above-described brake system, the correspondence between the brake operation amount and the brake fluid pressure can be freely changed. Since a switching device, an electromagnetic on-off valve, and a liquid absorber are additionally required and the configuration is complicated, there has been a problem that the device cost is slightly increased and a reliability of the brake system is slightly reduced.

The present invention has been made to solve these problems.

Means for Solving the Problems And the gist of the present invention is to provide the brake system
(A) a brake operating member, and (b) a pressurizing piston is disposed in the housing so as to be movable back and forth, and a pressurizing chamber and an auxiliary pressure chamber are formed before and after the pressurizing piston, respectively. And (c) a wheel cylinder connected to the pressurizing chamber and actuating a brake that suppresses the rotation of the wheels of the automobile by advancing the pressurizing piston based on the operating force of the vehicle. (D) signal output means for outputting a relation defining signal that defines a correspondence relation between a brake operation amount, which is an operation force or an operation stroke of a brake operation member, and a brake fluid pressure;
(E) an electrically controlled hydraulic pressure source connected to the auxiliary pressure chamber for generating an auxiliary pressure by electrical control; and (f) a brake hydraulic pressure connected to the electrically controlled hydraulic pressure source and having a height based on the brake operation amount. Even if the brake operation amount is the same, the electric control hydraulic pressure source is generated so that the auxiliary pressure chamber generates an auxiliary pressure having a height that generates a different brake hydraulic pressure in the pressurized chamber in accordance with the related regulation signal. And a hydraulic pressure source control means for controlling.

Here, the "master cylinder" may be a type to which a vacuum booster or a hydraulic pressure booster for boosting the operating force is added, or may be a type to which no booster or hydraulic pressure booster is added.

The “relation defining signal that defines the correspondence between the brake operation amount and the brake fluid pressure” is not limited to the signal that directly defines the correspondence, but the signal that indirectly defines the correspondence, that is, the brake operation amount. May directly define the correspondence between the parameter that changes in relation to the brake pressure and the parameter that changes in relation to the brake fluid pressure (for example, the auxiliary pressure in the present invention).

In the automotive brake system according to the present invention, for example, a plurality of correspondences between the brake operation amount and the brake fluid pressure are set, and from among these correspondences, an appropriate relationship is made according to the vehicle speed, which is the traveling speed of the vehicle, or the driver's intention display. Can be designed so as to select the appropriate one as the appropriate correspondence. And specifically, for example, the "signal output means" is configured to output a signal corresponding to the vehicle speed as a relation defining signal,
It has an operation member, and outputs a signal corresponding to the operation thereof as a related regulation signal, and "hydraulic pressure source control means"
For example, from a plurality of correspondences, a form corresponding to the relation definition signal is selected as an appropriate correspondence, and an auxiliary pressure having a height based on the appropriate correspondence and the actual brake operation amount is generated. Good.

Further, in the automotive brake system according to the present invention, only one correspondence between the brake operation amount and the vehicle body deceleration is set, and a target vehicle body deceleration corresponding to the actual brake operation amount is set according to the correspondence relationship. It can also be designed to generate an auxiliary pressure at a level that brings the actual vehicle deceleration closer to its target vehicle deceleration. Even if the correspondence between the brake operation amount and the vehicle body deceleration is not set to one, even if the brake operation amount is the same, if the friction coefficient and the like of the brake friction material are different, different levels of brake fluid pressure are generated. That is, the correspondence between the brake operation amount and the brake fluid pressure is changed based on the actual vehicle body deceleration and the target vehicle body deceleration. And when taking this aspect,
For example, the "signal output means" is configured to output a signal corresponding to the actual vehicle deceleration as a related regulation signal, and
The "hydraulic pressure source control means" may be, for example, of a type that generates an auxiliary pressure having a height based on the relationship defining signal, the actual brake operation amount, and the correspondence.

A plurality of correspondences between the brake operation amount and the vehicle body deceleration can be set. In this case, the "signal output means" outputs, for example, a signal corresponding to the vehicle speed as a first relation defining signal and a signal corresponding to the actual vehicle deceleration as a second relation defining signal. Or a form having an operation member, a signal corresponding to the operation is output as a first relation definition signal, a signal corresponding to the actual vehicle deceleration is output as a second relation definition signal, and
The "hydraulic pressure source control means" is selected, for example, from a plurality of correspondences according to the first relation definition signal as an appropriate correspondence, and the appropriate correspondence, the actual brake operation amount, and the second What is necessary is just to take the form which produces | generates the auxiliary pressure of the height based on a relationship regulation signal.

Further, the brake system according to the present invention may further include a fluid supply / discharge device connected to the pressurizing chamber for supplying the brake fluid thereto and discharging the brake fluid therefrom. This makes it possible to freely change the correspondence between the operation force of the brake operation member and the operation stroke. That is, for example, if the fluid supply / discharge device supplies the brake fluid to the pressurizing chamber during the brake operation, the operation stroke is shortened by an amount corresponding to the supply amount, and conversely, the brake fluid is discharged from the pressurizing chamber. If this is the case, the operation stroke will be lengthened by an amount corresponding to the discharge amount.

In the brake system according to the present invention, when the electric control hydraulic pressure source operates normally, the electric control hydraulic pressure source and the master cylinder cooperate to form the auxiliary pressure chamber formed behind the pressurizing piston. The brake pressure in the pressurizing chamber is controlled by controlling the auxiliary pressure. The brake hydraulic pressure to be generated in the master cylinder based on the operating force of the brake operating member is changed to an appropriate level by the electric control hydraulic pressure source. On the other hand, when the electric control hydraulic pressure source has failed, the brake hydraulic pressure having a height corresponding to the operating force is generated in the pressurizing chamber only by the master cylinder, as in the manual brake system.

In short, in the brake system according to the present invention, an appropriate amount of brake fluid is discharged from the master cylinder even in a state where the electric control hydraulic pressure source operates normally. Thus, it is not indispensable to provide an electromagnetic on-off valve and a liquid absorber in order to obtain an appropriate braking operation feeling. In addition, in the state where the electric control hydraulic pressure source has failed, since the auxiliary pressure chamber does not perform any operation, as in the above manual / electric dual system brake system,
When the electric control hydraulic pressure source has failed, it is not essential to provide a switching device for disconnecting the auxiliary pressure chamber from the electric control hydraulic pressure source.

Therefore, according to the present invention, the correspondence between the brake operation amount and the brake fluid pressure can be electrically controlled without providing the switching device, the electromagnetic on-off valve, and the liquid absorber, and the electric control can be performed. In addition to providing an appropriate brake operation feeling even during normal operation of the system, a brake system that can brake the vehicle without trouble even when the electric control system fails can be manufactured. That is, it is possible to keep the deterioration of the property small.

Examples Hereinafter, some examples of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 10 denotes a master cylinder. The master cylinder 10 is a tandem type in which two pressurizing pistons 14 and 16 are fitted to a bottomed cylindrical housing 12 in a liquid-tight and slidable manner. Since the master cylinder 10 is well known, it will be briefly described. 18 for brake fluid in master cylinder 10
, Reservoirs 20 and 22 are liquid supply passages, and 24 and 26 are compensation liquid passages. Reference numerals 28, 30, 32, 34 and 36 denote cup seals, reference numerals 40 and 42 denote pressurizing chambers, reference numerals 44 and 46 denote low pressure chambers, and reference numerals 48 and 50 denote springs. The hydraulic pressure generated in each of the pressurizing chambers 40 and 42 is
The power is transmitted to the rear wheel cylinders 56 of the left and right rear wheels and the front wheel cylinder 58 of the left and right front wheels via 2,54. The housing 12 is attached to a plate 60 that separates the housing 12 from the interior of the engine room.

From the center of the rear end face of the pressure piston 16,
An auxiliary piston 62 having a smaller diameter is extended and penetrates a liquid-tight and slidable closing member 64 fixed to the open end of the housing 12 in a liquid-tight manner, and is exposed to the atmosphere. The housing 12, the pressure piston 16, the auxiliary piston 62, the closing member 64, and the cup seal 66 allow the pressure piston 16
Auxiliary pressure chamber 70 is formed at the rear. Reference numeral 71 denotes a stopper. The auxiliary piston 62 has a bottomed hole from its rear end
An input rod 74 is fitted into the bottomed hole 72. The end of this input rod 74 has a bottomed hole
The rear end is connected to a brake pedal 78 as a brake operating member via a link mechanism 76. Reference numeral 79 denotes a stopper.

The pressurizing chambers 40 and 42 and the auxiliary pressure chamber 70 are respectively connected to actuators 80 and 82 using a piezoelectric element as a driving source. In the actuator 80, as shown in FIG. 2, a piston 86 is fitted in a housing 84 in a liquid-tight and slidable manner, whereby the space in the housing 84 is divided into two. The space in front of the piston 86 is the control liquid chamber
A plurality of piezoelectric elements 90 stacked and fixed to each other are accommodated in the rear space. In the control liquid chamber 88, a spring 92 that constantly urges the piston 86 toward the piezoelectric element 90 is provided. The thickness of the piezoelectric element 90 is increased by the application of a voltage, and the entire piezoelectric element 90 is elongated. Usually, the piezoelectric element 90 is kept in the most contracted state. When a voltage is applied to the piezoelectric element 90, the piston 86 moves forward (moves to the left in the figure).
Then, the volume of the control liquid chamber 88 is reduced, and when the voltage is removed, the piston 86 retreats (moves to the right in the drawing) to increase the volume of the control liquid chamber 88.

In contrast, actuator 82 is
The basic structure is the same as that shown in FIG. 3, and includes a housing 94, a piston 96, a control liquid chamber 98, a piezoelectric element 100, and a spring 102. However, a through hole 104 is formed in the center of the piston 96, and the through hole 104 is
6 communicates with the reservoir 108. Through hole 104
A check valve 110 that allows the flow of the brake fluid from the reservoir 108 to the control fluid chamber 98 but prevents the flow in the opposite direction is provided therein. If the piston 96 is in the retracted end position (the original position shown) because the piezoelectric element 100 is most contracted, the check valve 110 is forcibly opened by the pin 112 fixed to the housing 94 and the control liquid chamber 98 is opened. The flow of the brake fluid from the side to the reservoir 108 side is also allowed. That is, in the present embodiment, the actuator 82 and the reservoir 108 constitute an electric control hydraulic pressure source.

The actuators 80 and 82 are controlled by a controller 120 shown in FIG. Controller 120 is CPU12
2. A computer mainly composed of a ROM 124 and a RAM 126 connected to each other by a bus 128. The ROM 124 stores various control programs, including a brake fluid pressure control routine and a stroke control routine shown in the flowcharts of FIGS. Further, the ROM 124 includes an FG map that defines the correspondence between the pedaling force applied by the driver to the brake pedal 78 (this is one mode of the operating force in the present invention) and the deceleration to be generated on the vehicle body, Various maps are also stored, including a plurality of FL maps that define a plurality of correspondences between the pedaling force and the depression stroke of the brake pedal 78, which are set for each of a plurality of representative values of the vehicle speed. I have. FIG. 6 is a graph showing the correspondence between the pedaling force and the stepping stroke at low speed, medium speed, and high speed. The controller 120 includes, in addition to the actuators 80 and 82, a tread force sensor 130 that detects a tread force, and a stroke sensor 13 that detects a depression stroke of the brake pedal 78.
2 and the brake fluid pressure of the rear wheel cylinder 56 (even the brake fluid pressure of the front wheel cylinder 58
2, which is also connected to a fluid pressure sensor 134 for detecting the vehicle pressure, a vehicle speed sensor 136 for detecting the vehicle speed, and a deceleration sensor 138 for detecting the vehicle body deceleration.
Actuators 80 and 82 are controlled by CPU 122 executing each control program based on the output signal from 138.

 Next, the operation will be described.

When the power supply of the vehicle is turned on, the CPU 122 repeats the execution of each routine of FIGS. 4 and 5. At each time of execution of the brake fluid pressure control routine of FIG.
In S1 (hereinafter simply referred to as S1; the same applies to other steps), it is determined whether or not the depression of the brake pedal 78 has been started based on the output signal of the stroke sensor 132, that is, whether or not the depression stroke is not zero. Is determined. In this case, if the result of the determination is NO because the brake operation has not been performed, a signal for initializing the actuator 82, that is, a signal for setting the voltage of the piezoelectric element 100 to 0 is output in S8. Is completed. On the other hand, since the brake operation was started
If the determination result in S1 is YES, in S2, the pedaling force sensor 1
Based on the output signal of 30, the actual pedaling force actually applied to the brake pedal 78 is detected, and subsequently, in S3,
Using the FG map, a vehicle deceleration corresponding to the actual pedaling force is set as a target deceleration.

Thereafter, in S4, based on the output signal of the deceleration sensor 138, the actual deceleration actually occurring in the vehicle body is detected,
Subsequently, in S5, a target control amount of the brake fluid pressure in the pressurizing chambers 40 and 42 is calculated based on the difference between the actual deceleration and the target deceleration, and the auxiliary pressure chamber 70 is calculated based on the target control amount.
The target control amount of the auxiliary pressure is calculated.

During brake operation, pressurized pistons 14, 16 and input rod 7
The balance of force expressed by the following equation is maintained between 4 and 4.

rF + P _S S _S = P _B S _B where F: Treading force r: Treading force is boosted at link mechanism 76 and input rod 74
The boosting factor when applied to the pressure P _S : the auxiliary pressure in the auxiliary pressure chamber 70 S _S : the area of the pressure receiving surface where the auxiliary piston 62 receives the auxiliary pressure P _B : the brake fluid pressure S _{B in the} pressure chambers 40 and 42: The area of the pressure receiving surface on which the pressurizing pistons 14 and 16 receive the brake hydraulic pressure. The target control amount of the auxiliary pressure is calculated from the target control amount of the brake hydraulic pressure in consideration of the balance of the forces. That is, the deceleration sensor 138 forms an example of a `` signal output unit '' in a form of outputting a signal corresponding to the actual vehicle deceleration as a relation defining signal in cooperation with a part of the controller 120 that executes S4. It is. Thereafter, a target control amount of the voltage of the piezoelectric element 100 of the actuator 82 (hereinafter, simply referred to as a control amount of the actuator 82) is calculated based on the target control amount of the auxiliary pressure. A signal to be performed is output to the actuator 82. Thereafter, in S7, it is determined whether or not the current depression of the brake pedal 78 has been completed based on the output signal of the stroke sensor 132. Assuming that this is not the case this time, the result of the determination is NO, and the process returns to S2. Thereafter, the execution of S2 to 7 is repeated, but before the first execution of S2 to 7,
The check valve 110 is open because the piston 96 of the piston 82 is at the retreat end position, and the auxiliary pressure chamber 70 is communicated with the reservoir 108 via the control liquid chamber 98, the check valve 110, and the communication passage 106. Then, the execution of S2 to S7 is started, and the check valve 110 is closed when the piezoelectric element 100 is extended and the piston 96 advances a predetermined distance from the retreat end position, and thereafter, the control liquid chamber 98 is extended by the extension of the piezoelectric element 100. The state is such that the hydraulic pressure is increased in accordance with. At this time, since the control liquid chamber 88 of the actuator 80 is always in a state capable of increasing the pressure, if the execution of S2 to S7 is further repeated,
The auxiliary pressure is controlled by the actuator 82, and the pressurizing pistons 14 and 16 are operated accordingly, thereby controlling the brake fluid pressure. Even if the auxiliary pressure changes, the reaction force applied from the pressurizing piston 16 to the input rod 74 does not change.

While the execution of S2 to S7 is repeated, the brake pedal 78
Is released, and if the result of the determination in S7 is YES, one execution of this routine is completed via S8.

On the other hand, at the time of execution of the stroke control routine shown in FIG.
, It is determined whether or not the depression of the brake pedal 78 has been started, and if so, the actuator 80 is controlled to a standby state in S22. The piezoelectric element 90 of the actuator 80 is always in the most contracted state,
In this state, the brake fluid pressure in the pressurizing chambers 40 and 42 cannot be reduced to discharge the brake fluid from the pressurizing chambers 40 and 42. This is because in order to reduce the brake fluid pressure, it is necessary to increase the volume of the control fluid chamber 88, that is, to further contract the piezoelectric element 90. Therefore, in this step, in order to extend the piezoelectric element 90 to about half of the maximum expansion in advance in preparation for the decompression, a voltage of an appropriate magnitude for realizing the expanded state is applied to the piezoelectric element 90. You.

Note that the standby state is realized by this step when the pressurizing pistons 14 and 16 advance from the retreat end position to shut off the compensating liquid passages 24 and 26, that is, the pressurizing chambers 40 and 42 are shut off from the reservoir 18. Since it is designed to be completed by a certain time, the brake fluid pressure in the pressurizing chambers 40 and 42 does not increase because the piezoelectric element 90 is extended by executing this step.

Then, in S23, the actual pedaling force is detected based on the output signal of the pedaling force sensor 130, and in S24, the vehicle speed sensor 136 is detected.
The actual vehicle speed, which is the actual vehicle speed, is detected on the basis of the output signal, and in S25, a map corresponding to the actual vehicle speed among the plurality of FL maps is selected as an appropriate FL map, and the appropriate FL map is selected. Using the map, a depression stroke corresponding to the actual depression force is set as a target stroke. Subsequently, in S26, an actual stroke which is an actual depression stroke is detected based on the output signal of the stroke sensor 132, and in S27, a control amount of the actuator 80 is calculated based on a difference between the actual stroke and the target stroke. You. For example, if the actual stroke is longer than the target stroke, the control fluid chamber of the actuator 80
An appropriate control amount for reducing the volume of 88 and supplying the brake fluid from the actuator 80 to the pressurizing chambers 40 and 42 is calculated, while if the actual stroke is shorter than the target stroke, A control amount appropriate for increasing the volume and discharging the brake fluid from the pressurizing chambers 40 and 42 to the actuator 80 is calculated. Then, in S28,
The signal to the effect that the control amount should be controlled is
Output to 80. Pressurizing chamber by actuator 80
When the supply and discharge of the brake fluid is performed to and from the brake pedals 40 and 42, the brake fluid pressure in the pressurizing chambers 40 and 42 is temporarily changed slightly by the actuator 80, and the brake pedal 78
As long as the pedaling force is kept constant, the same change in the brake fluid pressure is caused in the auxiliary pressure. However, since the auxiliary pressure is controlled by the actuator 82 so as to cancel the change, the actuator 80 controls the pressurizing chambers 40 and 42.
Even if the supply and discharge of brake fluid to
The brake fluid pressure of 40, 42 is kept constant.

Thereafter, in S29, it is determined whether or not the current depression of the brake pedal 78 has been completed.If not, the process returns to S23.
Is restored to the initial state, that is, the most contracted state, the voltage of the piezoelectric element 90 is set to 0. This completes one execution of this routine.

As is clear from the above description, in the present embodiment, of the pedaling force sensor 130 and the controller 120, S in FIG.
The part that executes S2, S3, S5 and S6 constitutes an example of the "hydraulic pressure source control means".

In the above embodiment, the correspondence between the pedaling force and the deceleration is not changed, but may be changed. A plurality of correspondences between the pedaling force and the deceleration are set, and the correspondence between the pedaling force and the deceleration is made variable, for example, if the correspondence can be selected according to the driver's preference or the vehicle speed can be selected. It is possible.

In the above embodiment, the brake fluid pressure is controlled in accordance with the correspondence between the pedal effort and the deceleration. However, a plurality of correspondences between the pedal effort and the brake fluid pressure are set, and among them, The brake fluid pressure can also be controlled using a specific correspondence. Hereinafter, a preferred embodiment for realizing this embodiment will be described with reference to FIGS. 7 and 8. FIG.

In the ROM 124 of this embodiment, instead of the FG map,
Three FP maps each defining the correspondence between the pedaling force and the auxiliary pressure of the auxiliary pressure chamber 70 are stored. Each of these FP maps is for realizing the three correspondences between the pedaling force and the brake fluid pressure shown in the graph of FIG. In addition, the F-P
A select lever (not shown) for selecting a desired driver from the map is provided in the vehicle interior. The select lever can be operated at three positions: "normal", "hard", and "soft". ROM1
24 stores a brake fluid pressure control routine shown in FIG. 7 instead of the brake fluid pressure control routine shown in FIG.

During each execution of this brake fluid pressure control routine,
First, it is determined whether or not the depression of the brake pedal 78 has been started in S51, and if so, the actual pedaling force is detected based on the output signal of the pedaling force sensor 130 in S52. Thereafter, in S53, the operation position of the select lever is detected, and subsequently, in S54, the plurality of F
A map corresponding to the current operation position of the select lever is selected from the P maps as an appropriate FP map, and S55
, An auxiliary pressure corresponding to the actual pedaling force is set as a target auxiliary pressure using the appropriate FP map. In other words, the "signal output means" of a form in which the select lever outputs a signal corresponding to the operation by the driver as a relation defining signal in cooperation with the portion of the controller 120 that executes S53.
Constitutes another example. Thereafter, in S56, the actual brake fluid pressure, which is the actual brake fluid pressure, is detected based on the output signal of the fluid pressure sensor 134.
In step (1), an actual auxiliary pressure is calculated from the actual brake fluid pressure by using the above-mentioned equation of force balance. That is, the actual pedaling force F
And the actual brake fluid pressure P _B are known, the boosting factor r and the pressure receiving areas S _S and S _B are known, so that the actual auxiliary pressure P _S is obtained by calculation by using the equation of the force balance. You can do it.

Thereafter, in S58, the control amount of the actuator 82 is calculated based on the difference between the actual auxiliary pressure and the target auxiliary pressure, and subsequently, in S59, a signal indicating that the control is to be performed by the control amount is sent to the actuator 82. Output. Thereafter, in S60, it is determined whether or not the current depression of the brake pedal 78 has been completed.If not, the process returns to S52.If so, the actuator 82 is restored to the initial state in S61. One run ends.

As is apparent from the above description, in the present embodiment, the pedaling force sensor 130, the hydraulic pressure sensor 134, and the controller 120
Of these, the part that executes S52 and S54 to S59 in FIG. 7 constitutes another example of the "hydraulic pressure source control means".

In any of the embodiments described above, the auxiliary pressure chamber 70
Inside, an auxiliary pressure having a suitable height for generating a boost to the pressurizing pistons 14 and 16 by boosting the treading force is also generated. The generation of the auxiliary pressure is involved not only in controlling the brake hydraulic pressure but also in realizing the booster effect. Based on the latter fact, the vacuum booster and the hydraulic booster are omitted in the present brake system. . However, these boosters may be provided in the master cylinder 10 and the output rod of the booster may be engaged with the pressurizing piston 16 instead of the input rod 74. Will simply be involved in controlling the brake fluid pressure.

Further, in each of the embodiments, the pressurizing chambers 40, 4
Both the supply and discharge of the brake fluid to and from the auxiliary pressure are performed by the actuators 80 and 82 driven by the piezoelectric elements 90 and 100. For example, an electric motor, a ball screw rotated by the electric motor, Even if it is performed by a combination of a pressurizing piston or the like which is screwed into a ball screw and operates according to its rotation, a combination of a pump, an accumulator, a solenoid-operated hydraulic proportional control valve, etc. (The same type as the electric control hydraulic pressure source of the brake system).

Further, the "controller" in the present invention may perform anti-lock control for controlling brake fluid pressure so as not to cause an excessive slip on wheels at the time of vehicle braking by controlling the auxiliary pressure. Sometimes, traction control for controlling brake fluid pressure may be performed so that excessive slip does not occur on the wheels.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the present invention may be implemented in other various modified and improved forms based on the knowledge of those skilled in the art. it can.

[Brief description of the drawings]

FIG. 1 is a system diagram of a brake system according to one embodiment of the present invention and a front sectional view of a master cylinder. 2 and 3 are front sectional views of the actuators 80 and 82 in FIG. 1, respectively. 4 and 5 are flowcharts respectively showing a brake fluid pressure control routine and a stroke control routine stored in the ROM in FIG. FIG. 6 is a graph showing three examples of the correspondence between the pedaling force and the stepping stroke stored in the ROM. FIG. 7 shows RO in another embodiment.
4 is a flowchart illustrating a brake fluid pressure control routine stored in M. FIG. 8 is a graph showing three correspondences between the pedaling force and the brake fluid pressure stored in the ROM. 10: Master cylinder, 12: Housing 14, 16: Pressurizing piston 40, 42: Pressurizing chamber, 70: Auxiliary pressure chamber 74: Input rod, 78: Brake pedal 80, 82: Actuator

Claims (1)

(57) [Claims] 1. A brake operating member, and a pressurizing piston is disposed in a housing so as to be movable back and forth, and a pressurizing chamber and an auxiliary pressure chamber are formed before and after the pressurizing piston, respectively. A master cylinder in which brake fluid pressure is generated in the pressurized chamber by advancing the pressurized piston based on the operation force of the master cylinder; and a wheel cylinder that is connected to the pressurized chamber and that operates a brake that suppresses rotation of a wheel of the automobile. Signal output means for outputting a relationship defining signal for defining a relationship between a brake operation amount, which is an operation force or an operation stroke of the brake operation member, and the brake fluid pressure; connected to the auxiliary pressure chamber; An electric control hydraulic pressure source generated by electric control; and a brake hydraulic pressure connected to the electric control hydraulic pressure source and having a height based on the brake operation amount. Even if the brake operation amount is the same, an electrically controlled hydraulic pressure source is generated so that an auxiliary pressure having a height to generate a brake hydraulic pressure having a different height in the pressurizing chamber in accordance with the relationship defining signal is generated in the auxiliary pressure chamber. And a hydraulic pressure source control means for controlling.