JPH1120670A - Braking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately decide lowering of a booster ratio of a booster by deciding that the booster ratio of the booster becomes lower than a normal value when an increase is generated in an increase ratio of an operation stroke for an increase in master cylinder hydraulic pressure. SOLUTION: An inflow control valve 140 becomes an opened state when hydraulic fluid is required to be supplied from a master cylinder 14 to a reservoir 98 and allows flowing of hydraulic fluid from the master cylinder 14 to the reservoir 98. When the supply of hydraulic fluid from master cylinder 14 to the reservoir 98 is not required, the inflow control valve 140 becomes a closed state, prevents flow of hydraulic fluid from the master cylinder 14 to the reservoir 98 and enables boosting by the master cylinder 14. When pressure in a transformer chamber becomes atmospheric pressure, a booster 12 reaches a boosting limit, pressure of the transformer chamber is directly detected to be atmospheric pressure and a boosting limit decision is performed. Thus, accuracy deciding that the booster reaches the boosting limit can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device for braking a vehicle, and more particularly, to a brake device having a vacuum booster.

[0002]

2. Description of the Related Art Generally, the above-mentioned brake device includes (a) a brake operation member operated by a driver such as a brake pedal, (b) a master cylinder for generating a hydraulic pressure based on operation of the brake operation member, and (c) a booster that assists the operation force of the brake operating member and outputs the same to the master cylinder, and (d) a brake cylinder that is connected to the master cylinder by a fluid passage and that operates the brake by the fluid pressure supplied from the fluid passage. And a brake that suppresses the rotation of the wheels. Boosters are generally
(a) an input member that is displaced based on the operation of a brake operating member, (b) a power piston that is provided so as to be able to be displaced relative to the input member, and (c) a relative approach limit between the input member and the power piston. (D) a power piston driving device that operates the power piston by the power from the drive source based on the relative displacement between the input member and the power piston, and (e) the operating force of the power piston to the master cylinder. And an output member for outputting.

[0003]

SUMMARY OF THE INVENTION First, the applicant of the present invention applied a boosting factor to the brake device in order to detect a state where the boosting factor of the booster was reduced during the braking operation. It is proposed that a drop judgment device be provided, and further, the boost factor drop judgment device is set in a state where the booster reaches the assist limit based on the fact that the booster factor of the booster decreases when the booster reaches the assist limit. It is proposed to embodi it as an assist limit determination device that detects as a boost factor lowered state. The proposed assistance limit determination device is
(a) a master cylinder fluid pressure sensor that detects the master cylinder fluid pressure, and (b) a master cylinder fluid pressure based on a signal from the master cylinder fluid pressure sensor when the operating conditions of the booster are standard. When the booster reaches a height when the booster reaches the assisting limit, the booster includes an assisting limit determining unit that determines that the booster has reached the assisting limit. The operating condition of the booster is, for example, when the booster is a vacuum booster, the height of the pressure in the negative pressure chamber, and the boosting ability at the boosting limit of the booster is determined depending on the height.

[0004] However, it has been noticed that this embodiment has room for improvement. The operating conditions of the booster are not always standard, and if it is not, the master cylinder hydraulic pressure when the booster actually reaches the assisting limit also becomes non-standard. Nevertheless, in this specific example, since the operating limit of the booster is always assumed to be standard and the assisting limit is determined, it is expected that the determination accuracy will be reduced. Therefore, in this specific plan, it is necessary to make improvements in order to improve the determination accuracy.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a brake device that can accurately determine a reduction in boost factor of a booster.

[0006] This problem is solved by the brake device of the following mode. In the following description, each aspect of the present invention will be described in the same form as the claims, with the respective items numbered. This is to clarify the possibility of adopting the features described in each section in combination.

(1) A brake operating member operated by a driver, a master cylinder that generates a hydraulic pressure based on the operation of the brake operating member, and an operating force of the brake operating member to assist the master cylinder. A brake that is connected to the master cylinder by a liquid passage and has a brake cylinder that is operated by hydraulic pressure supplied from the liquid passage, and that includes a brake that suppresses rotation of a wheel; An operation stroke-related amount sensor for detecting an amount related to an operation stroke of a member, a master cylinder hydraulic-related amount sensor for detecting an amount related to the hydraulic pressure of the master cylinder, and an operation stroke-related amount sensor and a master cylinder liquid. Based on the signal from the pressure-related quantity sensor, A brake device comprising a boost factor reduction determining means for determining that the boost factor of the booster has fallen below a normal value when the increase rate of the operation stroke has increased. ). The present inventors have noticed that boosters generally have the following characteristics. That is, the rate of increase of the operation stroke with respect to the increase in the master cylinder hydraulic pressure is increased after the booster reaches the assisting limit and before the input member contacts the stopper, than before the assisting limit is reached, and ,
The characteristic is that, even before the booster reaches the assisting limit, the operating stroke increase rate increases when the brake operating member is operated quickly, compared to when the brake operating member is operated at a normal speed. Based on the general characteristics of such a booster, in the above-mentioned brake device,
When the operation stroke increase rate increases, it is determined that the booster rate of the booster has decreased. Therefore, when implementing this brake device in a mode in which the state in which the booster has reached the assisting limit is determined as the boost factor lowered state,
Regardless of whether the operating condition of the booster is standard or not, it is determined that the booster has reached the assisting limit when the booster actually reaches the assisting limit, and the accuracy of the determination is improved. Further, the brake device may be implemented in such a manner that a response delay state in which the operating force of the power piston cannot be increased following the stroke of the input member because the brake operating member is quickly operated is determined as a reduced power factor state. For example, the response delay of the booster can be correctly detected.
In this brake device, the “operation stroke-related amount sensor” is an operation stroke sensor that detects the operation stroke of the brake operation member, an input member stroke sensor that detects the stroke of the input member, or an interlocking member that works in conjunction with the input member. In addition, a sensor that detects a stroke of a member except for the brake operation member can be provided. The “master cylinder hydraulic pressure-related amount sensor” is a master cylinder hydraulic pressure sensor that detects the master cylinder hydraulic pressure, an output member operating force sensor that detects the operating force of the output member, or detects a vehicle body deceleration. The sensor may be a vehicle body deceleration sensor or a sensor that detects a physical quantity that changes according to the operating force of the output member and that excludes the master cylinder hydraulic pressure and the vehicle body deceleration. Further, in this brake device, the “booster” may be a vacuum booster using a negative pressure source as a driving source or a hydraulic booster using a high pressure source as a driving source. Further, in this brake device, the “normal value of the boost factor” is when the operating state of the booster is a normal state, that is, when the booster does not reach the assisting limit and no response delay occurs in the booster. The booster boost factor can be defined as the value to be taken. (2) the booster, (a) an input member that is displaced based on the operation of the brake operation member, (b) a power piston that is provided to be relatively displaceable with the input member, (c)
A stopper that defines a relative approach limit between the input member and the power piston, and (d) a power piston drive device that operates the power piston with power from a drive source based on a relative displacement between the input member and the power piston; e)
The brake device according to (1), including an output member that outputs an operating force of the power piston to the master cylinder. (3) The booster, wherein the drive source is a negative pressure source, and the power piston is movably provided in a booster housing, and a negative pressure chamber communicating the internal space of the booster housing to the negative pressure source. It is to be divided into a transformer room,
The power piston driving device selectively communicates the variable pressure chamber with a negative pressure chamber and the atmosphere based on a relative displacement between the input member and the power piston, and power is supplied by a differential pressure between the negative pressure chamber and the variable pressure chamber. The brake device according to item (2), which is a vacuum booster configured to operate a piston. (4) The brake device according to any one of (1) to (3), wherein the increase includes an absolute increase in which the operation stroke increase rate exceeds a set value. (5) The booster assists when the operating stroke or the master cylinder hydraulic pressure exceeds the reference value and the operating stroke increase rate exceeds the set value. The brake device according to the above mode (4), further comprising an assist limit reaching determination means for determining that the limit has been reached. The cause of the operating stroke increase rate exceeding the set value is that the booster has reached the assisting limit,
Sometimes the booster has a response delay. Therefore, only by judging whether or not the operation stroke increase rate has exceeded the set value, the reason why the operation stroke increase rate has exceeded the set value is that the booster has reached the assisting limit, or the response delay of the booster has been delayed. It cannot be determined whether it has occurred. On the other hand, when the booster reaches the assisting limit, the operating stroke or the master cylinder hydraulic pressure is usually increased to some extent. Therefore, in this brake device, it is determined that the booster has reached the assisting limit when the operation stroke or the master cylinder fluid pressure exceeds the reference value and the operation stroke increase rate exceeds the set value. Therefore, according to this brake device, it can be accurately determined whether or not the booster has reached the assisting limit. (6) The boost factor reduction determining means repeatedly acquires the operation stroke increase rate with time, and the increase is a relative increase in which the current acquisition value of the operation stroke increase rate increases from the previous acquisition value. The brake device according to any one of (1) to (3), including: (7) The boost factor reduction determining means determines whether or not the booster has reached the assisting limit based on the operating stroke increase rate, and after determining that the boosting limit has been reached, the operating stroke or As long as the master cylinder hydraulic pressure is equal to or greater than the magnitude at which the booster determines that the boost limit has been reached, the booster limit state determining means for determining that the booster is in the boost limit state is included (1) to (6).
The brake device according to any one of claims (claim 4). The increase in the operation stroke increase rate occurs only immediately after the booster shifts from the state before the assist limit to the state after the assist limit, and thereafter does not increase. On the other hand, after the booster is determined to have reached the assist limit in a certain series of brake operations, it is considered that the operating conditions of the booster do not change so much. Therefore, after the booster reaches the assisting limit based on the operation stroke increase rate, while paying attention to another physical quantity that changes before and after the booster assisting limit, the reference value to be compared with the physical quantity is determined by the operation stroke increase rate. May be determined to the value that the physical quantity had when the booster was determined to have reached the assisting limit based on the physical quantity. Based on the above knowledge, in the brake device, when it is determined that the operating stroke or the master cylinder hydraulic pressure has reached the assisting limit after it is determined that the booster has reached the assisting limit based on the operating stroke increase rate, It is determined that the booster is in the assisting limit state as long as it is equal to or larger than. Therefore, according to this brake device, it can be accurately determined whether or not the booster is in the assisting limit state. (8) the booster is a vacuum booster that assists the operating force by a differential pressure between a negative pressure chamber communicating with a negative pressure source and a variable pressure chamber selectively communicated with the negative pressure chamber and the atmosphere; The brake device further includes a booster pressure sensor that detects a pressure in a negative pressure chamber or a variable pressure chamber of the vacuum booster, and the boost factor reduction determining unit determines whether the vacuum booster has reached an assisting limit. (A) sensor abnormality determination means for determining whether the booster pressure sensor is abnormal,
(b) when the booster pressure sensor is not determined to be abnormal by the sensor abnormality determining means, while determining whether or not the vacuum booster has reached the assisting limit based on at least a signal from the booster pressure sensor, If it is determined that the booster pressure sensor is abnormal,
The brake device according to any one of (1) to (7), further including: limit determination means for determining whether or not the vacuum booster has reached an assisting limit based on the operation stroke increase rate. (9) Further, after the boost factor reduction determining means determines that the boost factor is reduced, the booster includes a pressure booster that increases the hydraulic pressure of the brake cylinder from the hydraulic pressure of the master cylinder (1) to The brake device according to any one of the above items (8) (Claim 5). According to this brake device, the operating force is assisted by the pressure booster in the state of reduced boost factor, so that even in the state of reduced boost factor, the braking effect is increased and the braking performance of the vehicle is improved. Is obtained. (10) the pressure intensifier, (a) provided in the middle of the fluid passage, allowing the bidirectional flow of hydraulic fluid between the master cylinder and the brake cylinder, and at least the brake cylinder from the master cylinder A control valve that switches to a plurality of states including a state in which the flow of the working fluid toward the liquid passage is blocked, and (b) a discharge side is connected between the control valve and the brake cylinder in the liquid passage, and from a suction side. (9) a pump that pumps up the working fluid and discharges it to the discharge side, and (c) a pump operating device that operates the pump after the boost factor reduction determining means determines that the boost factor has decreased (9). The brake device according to claim (claim 6). (11) The brake device according to (10), wherein the suction side of the pump is connected to a portion of the liquid passage between the master cylinder and the control valve. According to this brake device, there is obtained an effect that the pressure of the brake cylinder can be increased by effectively using the hydraulic pressure generated in the master cylinder during the brake operation. In this brake device, "the portion of the liquid passage between the master cylinder and the control valve" does not mean that the connection point between the master cylinder and the control valve in the liquid passage is excluded. The "side" may be directly connected to the pressurized chamber in the master cylinder where the hydraulic pressure is generated, or may be connected to the liquid passage extending from the pressurized chamber.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a more specific embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a brake device according to the present embodiment. The brake device is mounted on a four-wheel vehicle and includes a vacuum booster that assists a brake operation force.

The brake device further includes an anti-lock control device and an effectiveness characteristic control device. The anti-lock control device is a device that prevents the locking tendency of each wheel from becoming excessive during vehicle braking. This antilock control device has a pump, and the hydraulic fluid is recirculated in the brake circuit by the pump. On the other hand, the effectiveness characteristic control device considers that the vacuum booster has an assist limit, and makes the vehicle deceleration increase at substantially the same gradient with respect to the brake operating force regardless of before and after the assist limit when braking the vehicle. This is a device for controlling the braking effectiveness characteristic, which is the relationship between the brake operation force and the vehicle body deceleration. The effectiveness characteristic control device operates using the pump. That is, the pump is shared by the antilock control device and the effectiveness characteristic control device.

In FIG. 1, reference numeral 10 denotes a brake pedal as a brake operation member. The brake pedal 10 is a vacuum booster (hereinafter simply referred to as “booster”).
It is linked to a master cylinder 14 via 12.

As shown in FIG. 2, the booster 12 has a configuration similar to that of a conventional booster. The configuration will be specifically described below with reference to FIG. This will be specifically described based on the following.

The booster 12 has a hollow booster housing 15 as shown in FIG. The space in the booster housing 15 is divided into a negative pressure chamber 17 on the side of the master cylinder 14 and a brake pedal 10 by a power piston 16.
And a transformer chamber 18 on the side of. The negative pressure chamber 17
It is connected to a negative pressure source, such as an engine intake pipe, that generates a negative pressure by the operation of the engine.

The power piston 16 comprises: (a) a hub 16a supported movably back and forth by a booster housing 15;
And (b) a diaphragm 16b formed in an annular plate shape and attached to the hub 16a at the inner peripheral edge and attached to the booster housing 15 at the outer peripheral edge. The diaphragm 16 b has a stopper 1 for defining a retreat limit with respect to the booster housing 15.
6c is provided.

The hub 16a is slidably fitted to one end (right end in the drawing) of a booster piston rod 20 (an example of an output member) via a reaction disk 19 made of rubber on the side of the master cylinder 14. Have been combined. The other end (the left end in the figure) of the booster piston rod 20 is linked to the pressurizing piston of the master cylinder 14, whereby the booster piston rod 20 transfers the operating force of the power piston 16 to the master cylinder. To the 14 pressure pistons.

The hub 16a is connected to the brake pedal 10
On the side of the brake pedal 1 via the input member 21
0. The input member 21 includes a reaction rod 21a and a valve operating rod 21b.
And are connected coaxially. The reaction rod 21a is slidably fitted to the hub 16a, while the valve operating rod 21b is linked to the brake pedal 10 via a pedal operating mechanism (not shown). The relative approach limit and the relative separation limit of the reaction rod 21a to the hub 16a are defined by a stopper key 22 (an example of a stopper). The stopper key 22 includes the hub 16a and the reaction rod 21.
a at the same time, a large axial clearance is provided on the rear side of the stopper key 22 between the reaction rod 21a and the hub 16a.
, A small axial clearance is provided at the front side of the stopper key 22.

The distal end of the reaction rod 21a is engageable with the reaction disk 19, and does not engage when the booster 12 is not operating as shown in the figure, but engages when the booster 12 is operating as shown in FIGS. Then, a reaction force from the booster piston rod 20 acts on the reaction rod 21a.

The valve mechanism 2 is provided between the negative pressure chamber 17 and the variable pressure chamber 18.
3 (an example of a power piston drive mechanism) is provided. The valve mechanism 23 includes the valve operating rod 21
It operates based on the relative movement between b and the power piston 16, and includes a control valve 23a, an air valve 23b, a vacuum valve 23c, and a control valve spring 23d. Air valve 2
3b is a transformer chamber 1 in cooperation with the control valve 23a.
8 selectively communicates / blocks with the atmosphere, and is provided so as to be movable integrally with the valve operating rod 21b. Control valve 23a
Is attached to the valve operating rod 21b in a state where the control valve spring 23d biases the valve operating rod 21b so as to be seated on the air valve 23b. The vacuum valve 23c selectively communicates and shuts off the variable pressure chamber 18 with the negative pressure chamber 17 in cooperation with the control valve 23a, and is provided so as to be movable integrally with the power piston 16.

The hub 16a is provided with a passage 24 for communicating the variable pressure chamber 18 with the negative pressure chamber 17 via the vacuum valve 23c, and a passage 25 for communicating the variable pressure chamber 18 with the atmosphere via the air valve 23b. ing. The hub 16a is provided with an air cleaner element 26 in a hollow portion on the brake pedal 10 side. Also, between the hub 16a and the booster housing 15,
A return spring 27 for returning the power piston 16 to the retracted end position is provided.

Next, the operation of the booster 12 will be described with reference to FIGS. In these figures, only the main part of the booster 12 is shown in an enlarged manner.

In the non-operating state, as shown in FIG. 3, the control valve 23a is seated on the air valve 23b while being separated from the vacuum valve 23c, whereby the variable pressure chamber 18 is cut off from the atmosphere and the negative pressure chamber 17 is closed. It is made to communicate with. Therefore, in this state, the negative pressure chamber 17 is also turned into the variable pressure chamber 18 by the negative pressure of the negative pressure source (pressure lower than the atmospheric pressure).
Are also negative pressures of the same height.

On the other hand, in the transient state of the operating state, that is, in the state where the brake pedal 10 is being operated in the direction in which the master cylinder hydraulic pressure is increased, as shown in FIG. The control valve 23a is seated on the vacuum valve 23c relative to the power piston 16 and the variable pressure chamber 18 is shut off from the negative pressure chamber 17. Thereafter, if the valve operating rod 21b further approaches the power piston 16,
The air valve 23b is separated from the control valve 23a, whereby the variable pressure chamber 18 is communicated with the atmosphere.
In this state, the pressure in the variable pressure chamber 18 rises, and a differential pressure is generated between the negative pressure chamber 17 and the variable pressure chamber 18, and the power piston 16 is operated by the differential pressure.

In the holding state of the operating states, that is, in the state in which the operating force F of the brake pedal 10 is kept constant, as shown in FIG.
3a is seated on both the air valve 23b and the vacuum valve 23c, and the variable pressure chamber 18 is shut off from both the negative pressure chamber 17 and the atmosphere, whereby the pressure in the negative pressure chamber 17 is kept constant, and as a result, the power piston The operation force of No. 16 is also kept constant.

When the pressure in the variable pressure chamber 18 of the booster 12 becomes equal to that of the atmosphere, the booster 12 reaches the assisting limit. Thereafter, when the brake pedal 10 is further operated, the reaction rod 21a moves forward while crushing the reaction disk 19 without moving the power piston 16 forward. As a result, the reaction rod 21a relatively approaches the power piston 16, and eventually the stopper key 22a.
The axial clearance on the rear side between the shaft and the reaction rod 21a disappears, and thereby the stopper key 22 comes into contact. At this time, the front axial clearance between the stopper key 22 and the hub 16a of the power piston 16 also disappears, and as a result, the reaction rod 21a
Is pressed against the hub 16a via the stopper key 22. This state is the maximum assist state of the booster 12, and is shown in FIG. If the brake pedal 10 is further operated in this state, the reaction rod 21
a moves forward integrally with the power piston 16, and the operating force of the booster piston rod 20 is increased, whereby the master cylinder hydraulic pressure is increased.

When the brake pedal 10 is operated in the direction in which the master cylinder hydraulic pressure is reduced, the control valve 23a is seated on the air valve 23b as shown in FIG. On the other hand, the variable pressure chamber 18 is separated from the vacuum valve 23c, is isolated from the atmosphere, and communicates with the negative pressure chamber 17, whereby the pressure in the variable pressure chamber 18 is reduced. As a result, the negative pressure chamber 17 and the variable pressure chamber The differential pressure with the pressure 18 is also reduced.

The master cylinder 14 is of a tandem type, and as shown in FIG.
And two pressure pistons 31 are slidably fitted in series with each other. By operating the two pressurizing pistons 31 based on the output of the booster 12, each pressurizing chamber 3 formed in front of each pressurizing piston 31 is operated.
A hydraulic pressure of a height equal to 2 is generated.

A brake cylinder for operating the brake of the left front wheel FL and a brake cylinder for operating the brake of the right rear wheel RR are connected to one pressurizing chamber 32, and the other pressurizing chamber 32 is connected to the right front wheel FR. And a brake cylinder for operating the brake of the left rear wheel RL are connected. The brake is of a type (a disk type, a drum type, and the like) that suppresses rotation of the wheel by pressing a friction material against a friction surface of a rotating body that rotates together with the wheel by an operating force based on hydraulic pressure.

That is, this brake device is a diagonal two-system type in which two mutually independent brake systems are diagonally configured. Since these two brake systems have a common configuration, only one brake system will be described with text and drawings as a representative, and the description of the other brake system will be omitted.

As shown in FIG. 1, the master cylinder 14 is connected to a brake cylinder 50 of the left front wheel FL and a brake cylinder 50 of the right rear wheel RR through a main passage 48 (liquid passage). The main passage 48 is branched in a forked shape after extending from the master cylinder 14, and one main passage 54 and two branch passages 56 are connected to each other. Each brake cylinder 50 is connected to the tip of each branch passage 56.

A pressure control valve 60 as a control valve is provided in the main passage 54. The pressure control valve 60 controls the hydraulic pressure on the brake cylinder 50 side in the main passage 48 relative to the hydraulic pressure on the master cylinder 14 side. Specifically, the hydraulic fluid is discharged from the pump 62. In this state, when the brake cylinder hydraulic pressure is higher than the master cylinder hydraulic pressure but the differential pressure is equal to or lower than the target differential pressure, the flow of the hydraulic fluid from the pump 62 to the master cylinder 14 is blocked, and the brake cylinder hydraulic pressure is reduced. If the master cylinder hydraulic pressure is higher than the master cylinder hydraulic pressure and the differential pressure is going to be higher than the target differential pressure, the flow of the hydraulic fluid from the pump 62 to the master cylinder 14 is allowed to increase the brake cylinder hydraulic pressure higher than the master cylinder hydraulic pressure. Further, control is performed so that the differential pressure becomes the target differential pressure.

In this embodiment, the pressure control valve 60 is of a type that electromagnetically controls the differential pressure between the brake cylinder 50 and the master cylinder 14. Specifically, as shown in FIG. 8, the pressure control valve 60 includes a housing (not shown) and a valve 70 for controlling a flow state of hydraulic fluid between the master cylinder side and the brake cylinder side in the main passage 48. A valve seat 72 on which it should sit,
A solenoid 74 for generating a magnetic force for controlling the relative movement of the valve 70 and the valve seat 72 is provided.

In the pressure control valve 60, in a non-operating state (OFF state) where the solenoid 74 is not excited,
The resilient force of the spring 76 separates the valve 70 from the valve seat 72, thereby permitting bi-directional flow of the hydraulic fluid between the master cylinder side and the brake cylinder side in the main passage 48. When the brake operation is performed, the brake cylinder pressure is changed at the same pressure as the master cylinder pressure. During this braking operation, the valve 7
At 0, a force acts in a direction away from the valve seat 72. Therefore, as long as the solenoid 74 is not excited, even if the master cylinder fluid pressure, that is, the brake cylinder fluid pressure becomes high,
The valve 70 does not sit on the valve seat 72. That is, the pressure control valve 60 is a normally open valve.

On the other hand, in the operation state (ON state) in which the solenoid 74 is excited, the armature 78 is attracted by the magnetic force of the solenoid 74 and the armature 7
A valve element 70 as a movable member that moves integrally with 8 is seated on a valve seat 72 as a fixed member. At this time, the attraction force F based on the magnetic force of the solenoid 74 is applied to the valve 70.
_1, it acts on the sum and the mutually opposite between the elastic force F ₃ of the force F ₂ and the spring 76 based on the difference between the brake cylinder pressure and the master cylinder pressure. Magnitude of the force F ₂ is the difference between the brake cylinder pressure and the master cylinder pressure, the valve member 70 is expressed by the product of the effective pressure receiving area which receives the brake cylinder pressure.

The operating state (O) in which the solenoid 74 is excited
N state), the discharge pressure of the pump 62,
The cylinder pressure does not increase so much._Two ≦ F₁ -F_Three In the region where the relationship represented by the following formula is established, the valve 70
The hydraulic fluid from the pump 62 is seated on the valve seat 72,
The escape to the cylinder 14 is prevented, and the discharge of the pump 62 is performed.
The pressure increases and the master cylinder fluid
A hydraulic pressure higher than the pressure is generated. In contrast, the pump
The discharge pressure of 62, that is, the brake cylinder fluid pressure further increases.
And F_Two > F₁ -F_Three In the region where the relationship expressed by
The valve 70 is separated from the valve seat 72 and the hydraulic fluid from the pump 62
Is released to the master cylinder 14, so that the pump 6
The discharge pressure of 2, ie the brake cylinder fluid pressure, increases further
Addition is prevented. In this way, the brake
The elastic force F of the spring 76 is applied to the _Three Ignore
For example, the solenoid suction force F₁ 
, A hydraulic pressure higher by the differential pressure based on the pressure difference is generated.

The pressure control valve 60 is arranged such that the magnitude of the solenoid attraction force F ₁ changes linearly in accordance with the magnitude of the exciting current I of the solenoid 74 as shown in the graph of FIG. Designed for

As shown in FIG. 1, the pressure control valve 60 is provided with a bypass passage 82,
A check valve 84 is provided in the middle of Step 2. By any chance,
Even if the pressure control valve 60 is closed by the fluid force generated in the movable member in the pressure control valve 60 when the brake pedal 10 is operated, the flow of the hydraulic fluid from the master cylinder 14 to the brake cylinder 50 is ensured. To do that. The pressure control valve 60 is further provided with a relief valve 86 in parallel with it. This is to prevent the discharge pressure of the pump 62 from becoming excessive.

A pressure-intensifying valve 90, which is a normally-open electromagnetic on-off valve, is provided in the middle of each of the branch passages 56. Realize. A bypass passage 92 is connected to each pressure increasing valve 90, and a check valve 94 for returning hydraulic fluid is provided in each bypass passage 92. A reservoir passage 96 extends from a portion of each branch passage 56 between the pressure intensifying valve 90 and the brake cylinder 50 to form a reservoir 98.
Has been reached. A pressure reducing valve 100, which is a normally closed electromagnetic on-off valve, is provided in the middle of each of the reservoir passages 96, and realizes a reduced pressure state in which the flow of hydraulic fluid from the brake cylinder 50 to the reservoir 98 is allowed in an open state. The reservoir 98 is configured such that a reservoir piston 104 is fitted to the housing in a substantially airtight and slidable manner, and the hydraulic fluid is compressed by a spring 108 as an elastic member in a reservoir chamber 106 formed by the fitting. It is housed below.

The reservoir 98 is connected by a suction passage 110 to the suction side of the pump 62, and the discharge side of the pump 62 is connected by a discharge passage 114 to a portion of the main passage 48 between the pressure control valve 60 and the pressure increasing valve 90. Have been. The suction passage 110 is provided with a suction valve 116 as a check valve, and the discharge passage 114 is provided with a discharge valve 118 as a check valve. The discharge passage 114 is further provided with an orifice 120 as a throttle and a fixed damper 122, which reduces pulsation of the pump 62.

By the way, during execution of the effectiveness characteristic control, the pump 62 pumps up the hydraulic fluid from the reservoir 98 and discharges the hydraulic fluid to each brake cylinder 50 to increase the pressure of each brake cylinder 50. Unless the lock control is being executed, it is normal that there is no hydraulic fluid to be pumped into the reservoir 98. In order to ensure the execution of the effectiveness characteristic control, the reservoir 98 is operated regardless of whether the antilock control is executed. Needs to be replenished with hydraulic fluid. Therefore, in the present embodiment, a supply passage 130 extending from a portion of the main passage 54 between the pressurizing chamber 32 of the master cylinder 14 and the pressure control valve 60 and reaching the reservoir 98 is provided.

However, since the master cylinder 14 and the reservoir 98 are always communicated with each other through the supply passage 130, even if the brake pedal 10 is operated, the master cylinder 14 and the reservoir 98 must be in the reservoir 98 after the reservoir piston 104 has bottomed. Cannot be boosted, causing a delay in braking effectiveness. Therefore, an inflow control valve 140 is provided in the middle of the supply passage 130.

The inflow control valve 140 is connected to the master cylinder 14
When the hydraulic fluid needs to be supplied from the reservoir to the reservoir 98, the reservoir 98 is opened, and the master cylinder 14
Hydraulic fluid to the master cylinder 14
When it is not necessary to supply hydraulic fluid from the reservoir to the reservoir 98, the reservoir 98 is closed, and the master cylinder 14 moves to the reservoir 9.
The flow of the working fluid to 8 is blocked, and the pressure increase by the master cylinder 14 is enabled.

In this embodiment, the inflow control valve 140
Is a normally closed solenoid on-off valve. Further, in the present embodiment, it is determined whether or not it is necessary to introduce the hydraulic fluid from the master cylinder 14 during the antilock control, and there is no hydraulic fluid to be pumped by the pump 62 in the reservoir 98 during the antilock control. It is determined whether the hydraulic fluid is present or not, and the integrated value of the time when the pressure increasing valve 90 is in the pressure increasing state and the integrated value of the time when the pressure reducing valve 100 is in the pressure reducing state are calculated respectively. The operation is performed by estimating the remaining amount of the working fluid in the reservoir 98 based on the pressure increasing time and the pressure decreasing time.

FIG. 10 shows the electrical configuration of the brake device. The brake device includes an ECU (electronic control unit) 200 mainly composed of a computer including a CPU, a ROM, and a RAM. The ROM stores a braking effect characteristic control routine (shown in flowcharts in FIGS. 11 to 14) and an anti-lock control routine (not shown).
Thus, the effect characteristic control and the antilock control are respectively executed by using the RAM while using the RAM.

An operation stroke sensor 202 (an example of an operation stroke related amount sensor) is provided on the input side of the ECU 200.
And a booster pressure switch 204 (an example of a booster pressure sensor), a master cylinder hydraulic pressure sensor 206 (an example of a master cylinder hydraulic pressure-related quantity sensor), and a wheel speed sensor 208. The operation stroke sensor 202 detects an operation stroke S of the brake pedal 10 and outputs an operation stroke signal that defines the operation stroke S. The booster pressure switch 204 is a switch that outputs a booster pressure signal different in two states according to the pressure level of the transformation chamber 18. When the pressure of the transformation chamber 18 is lower than the atmospheric pressure, the OFF signal is output. ON if
Output a signal. The master cylinder fluid pressure sensor 206
Detecting the height of the master cylinder pressure P _M, and outputs the master cylinder fluid pressure signal defining the height. The wheel speed sensor 208 is provided for each wheel, detects the wheel speed of each wheel, and outputs a wheel speed signal that defines the wheel speed of each wheel.

On the other hand, a pump motor 210 for driving the pump 62 is connected to the output side of the ECU 200, and a motor drive signal is output to the pump motor 210.
The output side of the ECU 200 further includes the pressure control valve 60.
, The solenoids 212 of the pressure increasing valve 90 and the pressure reducing valve 100 and the solenoid 214 of the inflow control valve 140 are also connected. A current control signal for linearly controlling the magnetic force of the solenoid 74 is output to the solenoid 74 of the pressure control valve 60, while the solenoids 212 of the pressure increasing valve 90 and the pressure reducing valve 100 and the inflow control valve 14
0 solenoid 214 is connected to each solenoid 2
ON / OF for ON / OFF drive of 12,214
An F drive signal is output.

Here, the effect characteristic control by the ECU 200 will be described.

The booster 12 operates the brake pedal 10.
When the working force F increases to a certain value, the pressure in the transformation chamber 18 increases.
It rises to atmospheric pressure and reaches the assistance limit. Helping
After the limit, the booster 12 can assist the operating force F.
If you do not take any measures, the graph in Figure 15
As shown, the effectiveness of the brake decreases. Heel
Effective characteristic control is performed by focusing on the fact that
Specifically, as shown graphically in FIG.
After the star 12 reaches the assisting limit, the pump 62 is operated.
And the master cylinder pressure P_MMore differential pressure ΔP (brake
Cylinder hydraulic pressure P _BMaster cylinder hydraulic pressure P_MIncrease
Pressure (shown graphically in FIG. 17)
A high hydraulic pressure in the brake cylinder 50,
, Regardless of before or after the booster 12
Stabilizes the effect of

In the present embodiment, as a method for determining whether or not the booster 12 has reached the assisting limit, a determination method based on a signal from the booster pressure switch 204 includes:
A determination method based on signals from the operation stroke sensor 202 and the master cylinder hydraulic pressure sensor 206 is employed. The above-described determination method directly detects that the pressure of the variable pressure chamber 18 has reached the atmospheric pressure based on the fact that the booster 12 reaches the assisting limit when the pressure of the variable pressure chamber 18 has reached the atmospheric pressure. This is a method of performing the assist limit determination.

On the other hand, the later determination method is based on the following characteristics of the booster 12.

In FIG. 18, the brake pedal 10 is not operated.
When the operation is started from the position, the operation of the brake pedal 10 is performed.
Working force F and master cylinder pressure P_MAnd brake pedal 10
The relationship that is established with the operation stroke S of the
Have been. In the figure, the booster 12 has reached the
Operating force F, master cylinder hydraulic pressure P_MAnd operations
When the stroke S is "F₁”,“ P₁"And" S
₁". This graph was created by the present inventors.
This shows the booster characteristics confirmed by
The master cylinder is temporarily
Hydraulic pressure P_MIncrease rate d of operation stroke S with respect to increase amount of
S / dP_MIndicates a rapid increase. Before the aid limit
Operation stroke increase rate dS / dP at a certain time i_M
To dS _i/ DP_Mi”, At some time j immediately after the aid limit
Stroke increase rate dS / dP_MTo dS_j/
dP_Mj”, (DS_i/ DP_Mi) <(DS_j/ DP_MjThe relationship expressed by the following equation holds.

The reason why such characteristics occur is considered as follows. During the braking operation, after the pressure in the variable pressure chamber 18 becomes equal to the atmospheric pressure, even if the brake pedal 10 is further operated and the input member 21 is further advanced, the differential pressure between the negative pressure chamber 17 and the variable pressure chamber 18 is increased. Does not increase, and thus the operating force of the power piston 16 does not increase. Therefore, the input member 21 is advanced independently. The input member 21
Before abutment against the stopper key 22, the operation force in a direction that the master cylinder pressure P _M is increased to the booster piston rod 20, the reaction disc 19 is via grant without intervention power piston 16. Therefore, the input member 2
Before contacting the stopper key 22, the reaction disk 19 contacts the reaction disk 19 locally, so that the reaction disk 19 is easily crushed.
The increase amount of the force applied to the reaction disk 19 by the increase amount of one stroke, that is, the master cylinder hydraulic pressure P
_It becomes longer for the increase in _M. Therefore, the rate of increase in the stroke of the input member 21 with respect to the increase in the master cylinder pressure P _M, i.e., the operation stroke rate of increase dS / dP
_After the booster 12 reaches the assisting limit, _M increases before contact with the stopper key 22 as compared to before the assisting limit.

When the brake pedal 10 is further operated and the input member 21 is further advanced, the input member 21 comes into contact with the stopper key 22. In this contact state, the input member 21 comes into contact with the master cylinder hydraulic pressure. the actuating force in a direction where P _M is increased to the booster piston rod 20, is granted through the stopper key 22, the power piston 16 and the reaction disc 19. Therefore, after the input member 21 contacts the stopper key 22, the input member 21 entirely contacts the reaction disk 19 via the power piston 16, so that the reaction disk 19 is not easily crushed. increase of force increase in the stroke of the member 21 is applied to the reaction disc 19, i.e., shorter in proportion of increase of the master cylinder pressure P _M. Therefore, the operation stroke increase rate d
S / dP _M is, after abutment of the stopper key 22, the stopper key 2 from the time the booster 12 has reached the boosting limit
It decreases compared to the time when it comes into contact with 2. Further, after the input member 21 in contact with the stopper key 22, the input member 21 is integrally move forward and the power piston 16 and the booster piston rod 20, whereby the booster master cylinder pressure P _M is due to the booster 12 Without pressure, and therefore the master cylinder pressure P _M
Is raised with a gentler slope before the assisting limit with respect to the operating force F.

[0053] Incidentally, temporarily immediately after the booster 12 has reached the boosting limit, because the characteristic that an increase in the operation stroke rate of increase dS / dP _M occurs occurs, the input member 21
Does not have to engage the booster piston rod 20 indirectly or directly via the reaction disc 19 before it abuts the stopper key 22. Only when the input member 21 abuts on the stopper key 22 does the booster of the type in which the input member 21 indirectly or directly engages with the booster piston rod 20, that is, after the booster 12 reaches the assisting limit, ,
Until the input member 21 comes into contact with the stopper key 22, this also occurs in a booster in which the input member 21 does not directly or indirectly engage with the booster piston rod 20.

The characteristics of the booster 12 have been described above.
The latter determination method makes use of the characteristics to determine the assistance limit.

One specific example of the determination method thereafter is the brake
Operation stroke increase rate dS / dP during operation_MThis time value of
A relative determination method that determines whether the value has increased from the previous value
However, in this embodiment, the operation is performed during the brake operation.
Stroke increase rate dS / dP _MIs the set value X (one of the set values).
Example) Absolute determination method to determine whether it is larger
It has been. However, this absolute decision method is adopted
In this case, as shown in FIG.
, The operation stroke increase rate dS / dP_MIs large
Booster 12 actually helps
Even though the limit has not been reached,
There is a possibility that the wrong judgment is made. There
Then, in the present embodiment, the booster 12
When it reaches the master cylinder pressure P_MBut somewhat high
Increased operating stroke based on the fact that
Rate dS / dP_MBecomes larger than the set value X, and
Ta cylinder pressure P_MIs the reference value P_A(Example of reference value)
Booster 12 reaches assist limit when high
Is determined to have been made.

[0056] provided that the operation stroke increase dS / dP _M is greater than the set value X, not the booster 12 is established continuously during the period in the boosting limit state,
It is only temporarily established immediately after the booster 12 reaches the assisting limit. Therefore, even after it is determined that the booster 12 has reached the assisting limit because the above two conditions are satisfied at the same time, if it is determined in the same manner whether the two conditions are satisfied at the same time, the booster 12 In fact, it is determined that the vehicle is not in the assisting limit state even though it is in the assisting limit state. Therefore, in the present embodiment, after the two conditions are satisfied at the same time, the assist limit determination is performed according to another rule applicable throughout the entire assist limit state, not only immediately after the assist limit is reached. Specifically, the height of the master cylinder pressure P _M when the two conditions are satisfied at the same time as the reference value P _M0, unless the current value of the master cylinder pressure P _M is higher than the reference value P _M0, booster 12 is determined to be in the assist limit state.

In the present embodiment, if the booster pressure switch 204 is normal, the assist limit determination is performed by the previous determination method, while if abnormal, the boost limit determination is performed by the subsequent determination method. It has become.

The details of the effect characteristic control that has been schematically described above will be specifically described based on the brake effect characteristic control routine shown in FIGS.

[0059] This routine ignition switch after being operated to the ON position from the OFF position, is repeatedly executed every predetermined time T ₀ by the driver. In each execution, first, in step S1 (hereinafter simply referred to as “S1”; the same applies to other steps), a master cylinder pressure signal is taken in from the master cylinder pressure sensor 206. Next, in S2, an operation stroke signal is fetched from the operation stroke sensor 202. Thereafter, in S3, it is determined whether or not the booster pressure switch 204 is abnormal. Booster pressure switch 2
It is determined whether there is an abnormality such as disconnection or short-circuit in 04. Subsequently, in S4, it is determined whether or not the determination in S3 indicates that the booster pressure switch 204 is abnormal. Assuming that this does not indicate that there is an abnormality this time, the determination is NO, the booster pressure signal is taken in from the booster pressure switch 204 in S5, and then, in S6, the booster pressure signal Based on this, it is determined whether or not the booster 12 is in the assisting limit state (regardless of whether the booster 12 has just reached the assisting limit or not). Specifically, if the booster pressure signal is an OFF signal because the pressure in the transformation chamber 18 is lower than the atmospheric pressure,
If it is determined that the booster 12 is not in the assisting limit state, while if the booster pressure signal is an ON signal because the pressure in the variable pressure chamber 18 has reached the atmospheric pressure, it is determined that the booster 12 is in the assisting limit state.

This time, assuming that the booster 12 is not in the assist limit state, the determination is NO, and in S7,
End processing of the pressure increase control is performed. Details of step S7 are shown in a flowchart of FIG. 12 as a termination processing routine. In this end processing routine, first, S41
At the time, the solenoid 74 of the pressure control valve 60
A signal for turning off is output, a signal for turning it off is output to the solenoid 214 of the inflow control valve 140 in S42, and a signal for turning it off is output to the pump motor 210 in S43. This completes one execution of the end processing routine, thereby ending one execution of the braking effect characteristic control routine.

On the other hand, if it is assumed that the booster 12 is in the assisting limit state this time, the determination in S6 becomes YES and the pressure increase control is performed in S8. The details of S8 are shown in the flowchart of FIG. 13 as a pressure increase control routine. In this pressure increase control routine, first, in S51, based on the current value of the master cylinder pressure P _M, the amount to push increase the brake cylinder pressure P _B from the master cylinder pressure P _M, i.e., the master cylinder 14 The target differential pressure ΔP with the brake cylinder 50 is determined. The ROM, as shown graphically in Figure 19, the master cylinder fluid height of pressure P _M when the the reference value P _M0 (S6 determines the current value of the master cylinder pressure P _M is changed from NO to YES ) and relationship is stored in the increment IP _M and the target differential pressure ΔP from the target differential pressure ΔP in accordance with the relationship
Is determined this time. The relationship after the boosting limit of the booster 12, are set so that the relationship that the brake cylinder pressure P _B increases linearly in the same gradient as before boosting limit to the operation force F is realized.

Thereafter, in S52, a current value I to be supplied to the solenoid 74 of the pressure control valve 60 is determined according to the determined target differential pressure ΔP. The relationship between the target differential pressure ΔP and the solenoid current value I is stored in the ROM, and the solenoid current value I corresponding to the target differential pressure ΔP is determined according to the relationship. Subsequently, in S53, the current is supplied to the solenoid 74 of the pressure control valve 60 with the determined solenoid current value I, whereby the pressure control valve 60 is controlled. Then, in S54, the inflow control valve 140 is controlled.

FIG. 14 is a flowchart showing the details of S54 as an inflow control valve control routine.

First, in S61, it is determined whether or not the antilock control is currently being executed. Assuming that it is not being executed, the determination is NO, and in S62, a signal for turning on the solenoid 214 of the inflow control valve 140, that is, a signal for opening the inflow control valve 140 is output. As a result, a state in which the hydraulic fluid can be introduced from the master cylinder 14 to the pump 62 via the supply passage 130 is established. This completes one execution of this routine.

On the other hand, if it is assumed that the antilock control is currently being executed, the determination in S61 is YES, and the determination in S61 is YES.
At 63, an operation for estimating the amount of the operating fluid existing as the operating fluid to be pumped by the pump 62 in the reservoir 98, that is, an operation for estimating the remaining amount of the reservoir is performed.
Subsequently, in S64, the estimated reservoir remaining amount becomes zero.
That is, it is determined whether there is no hydraulic fluid to be pumped by the pump 62 in the reservoir 98. Assuming that the remaining amount of the reservoir is not 0 this time, the determination is NO, and in S65, a signal to turn off the solenoid 214 of the inflow control valve 140,
That is, a signal for closing the inflow control valve 140 is output. On the other hand, if it is assumed that the remaining amount of the reservoir is 0 this time, the determination in S64 becomes YES, and in S62, a signal for causing the inflow control valve 140 to open it is output. In any case, one cycle of the inflow control valve control routine is completed.

It should be noted that the flow control valve control routine can be improved by directly detecting the remaining amount of the working fluid in the reservoir 98 by a sensor. The remaining amount is, for example, the reservoir piston 10 in the reservoir 98.
4 can be detected by providing a permanent magnet integrally movably and providing a reed switch as a sensor in proximity to the permanent magnet.

Thereafter, in S55 of FIG. 13, a signal for turning on the pump motor 210 is output to the pump motor 210. Thereby, the hydraulic fluid from the reservoir 98 is pumped up by the pump 62, hydraulic fluid is discharged to each brake cylinder 50, so that only the target differential pressure ΔP is higher hydraulic pressure than the master cylinder pressure P _M in the brake cylinder 50 Generated. This completes one execution of the pressure increase control routine, thereby ending one execution of the brake effect characteristic control routine.

The case where the booster pressure switch 204 is normal has been described above.
The determination in S4 is YES, and the process proceeds to S9 and subsequent steps.

In S9, whether the flag F is 1 or not
Is determined. This flag F is set when the computer is turned on.
This flag is set to 0 in response to the entry, not 1 this time
As a result, the determination is NO, and in S10, the operation is performed.
Stroke increase rate dS / dP_MIs calculated. This performance
The formula is the current value of the operation stroke S as S_(n), The previous value
S_(n-1)And the master cylinder pressure P_MThis time value of
To P_{M (n)}, The previous value is P_{M (n-1)}Then, dS / dP_M= (S_(n)-S_(n-1)) / (P_{M (n)}−P
_{M (n-1)}). In this equation, the fraction of the right-hand side
The numerator is a constant time T of the operation stroke S.₀Change of hit
While the denominator is the master cylinder hydraulic pressure P _MOne
Fixed time T₀It represents the amount of change per hit.

[0070] Thereafter, in S11, whether the computed operation stroke rate of increase dS / dP _M is greater than the set value X is determined. Assuming that it is not large this time, the determination is NO, and in S13, the termination processing is performed in the same manner as in S7, and subsequently, in S14, a signal for setting the flag F to 0 is output. You. Thus, one execution of the brake effect characteristic control routine is completed.

[0071] In contrast, assuming the calculated operation stroke rate of increase dS / dP _M is larger than the setting value X, an affirmative decision (YES) is obtained in S11, in S12, the current value of the master cylinder pressure P _M is whether higher than the reference value P _A is determined. This time, assuming it ’s not expensive,
The determination is NO and the process proceeds to S13. However, if it is assumed to be high this time, the determination is YES and the process proceeds to S15. In S15, it is determined that the booster 12 has just reached the assisting limit, and subsequently, in S16, the flag F is set to 1. That is, the flag F is 1,
It is a flag indicating that it is just after reaching the assisting limit in S15, and is a flag indicating that it is not after it is judged that it is immediately after reaching the assisting limit in S15. Thereafter, in S17, the RAM as the current value is the reference value P _M0 of the master cylinder pressure P _M (height of the master cylinder pressure P _M when the booster 12 is determined to be immediately after the arrival of the boosting limit) Then, in S18, pressure increase control is executed in the same manner as in S8. Thus, one execution of the brake effect characteristic control routine is completed.

Thereafter, if the present routine is executed again, since the current flag F is 1, the determination in S9 is YES.
Next, either with S10~S12 and S15~S17 are skipped, in S19, whether the present value of the master cylinder pressure P _M is higher than the reference value P _M0, i.e., the booster 12 is in the boosting limit state No (ie, not immediately after reaching the assisting limit, but in a state where the booster 12 cannot assist). In this case, assuming that the pressure is high, the determination is YES, and the pressure increase control is performed in S18. On the other hand, assuming that the pressure is not high, the determination is NO, and the termination process is performed in S13.
At 4, the flag F is set to 0. This completes one execution of this routine.

As is clear from the above description, in this embodiment, the vacuum booster 12 is a “booster”.
The operation stroke sensor 202 forms an example of an “operation stroke-related amount sensor”, the master cylinder hydraulic pressure sensor 206 forms an example of a “master cylinder hydraulic-related amount sensor”, and FIG. 11 S
1, S2, S9 to S12, S14 to S17 and S19
Is an example of the "power factor reduction determination means". In addition, S1, S
The part executing steps S2, S10, S11, S12 and S15 constitutes an example of "assistance limit reaching determination means".
The part that executes S9, S14, S16, S17 and S19 constitutes an example of the "assistance limit state determination means". The booster pressure switch 204 and the master cylinder hydraulic pressure sensor 206 (sensor unit)
200, S3 to S8, S13 and S18 in FIG.
(Control unit), the pressure control valve 60, the pump 62, the pump motor 210, and the inflow control valve 140 (actuator unit) cooperate with each other to constitute an example of the "pressure increasing device". . Further, the pressure control valve 60 constitutes an example of a “control valve”, the pump 62 constitutes an example of a “pump”, and a part of the ECU 200 that executes S43 of FIG. 12 and S55 of FIG. "
This constitutes an example.

While the preferred embodiment of the present invention has been described in detail with reference to the drawings, various modifications and changes may be made based on the knowledge of those skilled in the art without departing from the scope of the claims.
It goes without saying that the present invention can be implemented in an improved form.

[Brief description of the drawings]

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

FIG. 2 is a side sectional view showing the vacuum booster 12 in FIG. 1 together with a master cylinder 14.

FIG. 3 is a side sectional view showing a main part of the vacuum booster of FIG. 2 in an inoperative state in an enlarged manner.

FIG. 4 is a side cross-sectional view of a main part, in which a transition state of the operation state of the vacuum booster is enlarged.

FIG. 5 is a side cross-sectional view of a main part, showing an enlarged holding state of the operation state of the vacuum booster.

FIG. 6 is an enlarged side sectional view showing a main part of the operating state of the vacuum booster.

FIG. 7 is a side cross-sectional view of a main part, in which a released state of the operation states of the vacuum booster is enlarged.

FIG. 8 is a front sectional view for explaining the structure and operation of the pressure control valve 60 in FIG.

9 is a graph showing the relationship between the solenoid excitation current I and the solenoid attractive force F ₁ in the pressure control valve 60.

FIG. 10 is a block diagram showing an electrical configuration of the brake device.

11 is a flowchart showing a braking effect characteristic control routine stored in a ROM of a computer of ECU 200 in FIG.

FIG. 12 is a flowchart showing details of S7 and S13 in FIG. 11 as an end processing routine.

FIG. 13 is a flowchart showing details of S8 and S18 in FIG. 11 as a pressure increase control routine.

FIG. 14 is a flowchart showing details of S54 in FIG. 13 as an inflow control valve control routine.

15 is a graph showing the relationship between the operating force F and brake cylinder pressure P _B in the general brake system provided with a vacuum booster.

FIG. 16 is a graph for explaining the principle of effect characteristic control in the brake device according to the embodiment.

In FIG. 17 above embodiment, the master cylinder pressure P _M, is a graph showing the relationship between the differential pressure ΔP between the master cylinder pressure P _M and the brake cylinder pressure P _B.

18 is a graph showing the relationship between the operating force in the general brake system provided with a vacuum booster F and the master cylinder pressure P _M and operating stroke S.

FIG. 19 shows the master cylinder hydraulic pressure in the embodiment.
P_MReference value P_M0Incremental IP from _MAnd the target differential pressure ΔP
It is a graph which shows a relationship.

[Explanation of symbols]

 Reference Signs List 10 brake pedal 12 vacuum booster 14 master cylinder 17 negative pressure chamber 18 variable pressure chamber 19 reaction disk 20 booster piston rod 21 input member 22 stopper key 23 valve mechanism 60 pressure control valve 62 pump 200 ECU 202 operating stroke sensor 206 master cylinder hydraulic pressure sensor

Claims (7)

[Claims] 1. A brake operating member operated by a driver, a master cylinder for generating a hydraulic pressure based on an operation of the brake operating member, and an operating force of the brake operating member is assisted and output to the master cylinder. A brake device, comprising: a booster, and a brake connected to the master cylinder through a liquid passage, the brake cylinder having a brake cylinder that is operated by hydraulic pressure supplied from the liquid passage, and that suppresses rotation of a wheel. An operation stroke related amount sensor for detecting an amount related to the operation stroke of the master cylinder, a master cylinder hydraulic pressure related amount sensor for detecting an amount related to the hydraulic pressure of the master cylinder, the operation stroke related amount sensor and the master cylinder hydraulic pressure Based on the signal from the related quantity sensor, When increasing the increase rate of the serial operation stroke has occurred, the brake device characterized by boosting rate of the booster is provided a boosting factor reduction determining means determines that lower than normal value. 2. The brake device according to claim 1, wherein the increase includes an absolute increase in which the operation stroke increase rate exceeds a set value. 3. The booster according to claim 1, wherein said boosting factor reduction determining means determines that said operating stroke or said master cylinder fluid pressure exceeds a reference value and said boosting rate exceeds said set value. The brake device according to claim 2, further comprising an assist limit reaching determination unit that determines that the vehicle has reached the assist limit. 4. The boosting factor reduction determining means determines whether or not the booster has reached an assisting limit based on the operating stroke increase rate, and determines that the booster has reached an assisting limit. 4. A boost limit state determining means for determining that the booster is in the boost limit state as long as the stroke or the master cylinder hydraulic pressure is equal to or greater than the magnitude at which the booster determines that the boost limit has been reached. The brake device according to any one of the above. 5. A pressure increasing device for increasing the hydraulic pressure of the brake cylinder from the hydraulic pressure of the master cylinder after the boosting factor determining means determines that the boosting factor has decreased. 5. The brake device according to any one of 1 to 4. 6. The pressure-intensifying device is: (a) provided in the middle of the fluid passage to allow a bidirectional flow of hydraulic fluid between the master cylinder and the brake cylinder; A control valve that switches to a plurality of states including a state in which a flow of hydraulic fluid toward the master cylinder is blocked; and (b) a discharge side is connected between the control valve and the brake cylinder in the liquid passage, and suction is performed. A pump that pumps hydraulic fluid from the side and discharges it to the discharge side,
6. The brake device according to claim 5, further comprising: (c) a pump operating device that operates the pump after the boost factor reduction determining means determines that the boost factor has decreased. 7. The brake device according to claim 6, wherein the pump has a suction side connected to a portion of the liquid passage between the master cylinder and the control valve.