JPH10310040A - Braking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute a pressure intensifying control by which working of a brake can be stably controlled even without detecting related quantity of braking operation state quantity by utilizing speed reduction gradient of a car body before the starting of the pressure intensifying control. SOLUTION: A speed reduction gradient SP before a control is acquired as inclination of a straight line when a plurality of car body speed reduction G which are successively detected from just after the starting of a braking operation up to just before the formation of the starting condition of a pressure intensifying control are approximated by the straight line. The speed reduction gradient SP before the control is determined as it is for target speed reduction gradient SD to be realized in the pressure intensifying control. Pressure intensifying quantity ΔP for master cylinder hydraulic pressure PM of brake cylinder hydraulic pressure PB is determined so as to increase car body speed reduction G by the gradient. Thus, the car body speed reduction G increases by the same gradient, regardless of before and after the assisting limit of a booster, and the working of a brake is stabilized. Because the pressure intensifying control can be performed even if an abnormality is generated in a master cylinder hydraulic pressure sensor, reliability for a failure of a braking device is 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 pressure increasing control for increasing a brake cylinder pressure to a pressure higher than a master cylinder pressure during a brake operation. Related to a simple brake device.

[0002]

2. Description of the Related Art Generally, the above-mentioned brake device includes (a) a brake operating member such as a brake pedal, (b) a master cylinder for generating a hydraulic pressure based on an operating force of the brake operating member, and (c) a wheel. It is configured to include a brake that suppresses rotation, and (d) a brake cylinder that is connected to the master cylinder by a fluid passage and that operates the brake based on fluid pressure supplied from the fluid passage.

[0003]

Problems to be Solved by the Invention, Means for Solving Problems, Functions and Effects As one type of this type of brake device, the present applicant has previously developed the following. It is a brake device which is made to be able to freely control the effectiveness of the brake, which is the relationship between the brake operation state quantity and the brake cylinder fluid pressure, and further comprises (e) an operation state quantity of the brake operation member. (F) during operation of the brake operating member, when the start condition is satisfied during the operation of the brake operating member, the hydraulic pressure of the brake cylinder is detected by the master cylinder. Initiate pressure increase control to increase the hydraulic pressure to a level higher than the hydraulic pressure. In the pressure increase control, the brake cylinder is controlled based on the brake operation state amount-related amount detected by the brake operation state amount-related amount sensor during the pressure increase control. And a pressure increasing control device that controls the level of the hydraulic pressure.

Here, the brake operation state amount-related quantity sensor includes a pedal depression force sensor, a pedal stroke sensor, a master cylinder hydraulic pressure sensor, and the like, and assists a pedal depression force between the brake operation member and the master cylinder. When a vacuum or hydraulic booster is provided, there is also a booster pressure sensor that detects the pressure in a booster variable pressure chamber whose pressure changes according to the pedal depression force.

If the developed brake device is implemented,
For example, it is possible to make the temporal change gradient of the brake cylinder fluid pressure substantially the same before and after the pressure increase control. For example, when the booster is provided between the brake operating member and the master cylinder In addition, the temporal change gradient of the brake cylinder hydraulic pressure can be made substantially the same regardless of before and after the boosting limit of the booster, so that the braking effect is stabilized and the brake operation feeling is improved.

Subsequently, as a result of further research, the present applicant has noticed the following fact. In the brake device developed above, the detection of the brake operation state quantity related amount is not indispensable for the execution of the pressure increase control, and the vehicle body deceleration is detected before the pressure increase control is started. When the deceleration gradient was acquired, the fact that the pressure increase control could be executed based on the acquired deceleration gradient was noticed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. It is an object of the present invention to execute a pressure increasing control capable of controlling the braking effect and to execute a deceleration gradient before starting the pressure increasing control. Is to provide a brake device capable of executing the pressure increase control without detecting the brake operation state amount-related amount by utilizing the above.

This problem is solved by a brake device according to 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, a master cylinder for generating a hydraulic pressure based on the operating force of the brake operating member, a brake for suppressing the rotation of the wheels, and a brake passage connected to the master cylinder by a liquid passage. In a brake device including a brake cylinder that operates the brake based on a hydraulic pressure supplied from a liquid passage, a deceleration gradient obtaining unit configured to obtain a deceleration gradient that is a temporal change gradient of a vehicle body deceleration; During the operation of the operating member, when the start condition is satisfied, the pressure increase control for increasing the hydraulic pressure of the brake cylinder to a hydraulic pressure higher than the hydraulic pressure of the master cylinder is started. Based on the pre-control deceleration gradient which is the deceleration gradient acquired by the deceleration gradient acquiring means after the start and before the start of the pressure increase control. A brake control device including a booster control device that controls a height of the brake cylinder hydraulic pressure (claim 1). In this brake device, pressure increase control for increasing the hydraulic pressure of the brake cylinder to a hydraulic pressure higher than the hydraulic pressure of the master cylinder is performed during the braking operation. Further, in the pressure increase control, the height of the brake cylinder hydraulic pressure is controlled based on the pre-control deceleration gradient that is the deceleration gradient acquired before the start. In the pressure increase control, the target deceleration gradient during the pressure increase control is determined in consideration of the deceleration gradient before the start, and the brake cylinder fluid pressure is controlled so as to realize the target deceleration gradient. . Therefore, according to this brake device, it is possible to execute the pressure increase control capable of controlling the effect of the brake, and to execute the pressure increase control without detecting the brake operation state amount related amount. In this brake device, the "pressure increase control device" generally determines a control target value (the height of the brake cylinder fluid pressure, the pressure increase amount of the brake cylinder fluid pressure with respect to the master cylinder fluid pressure, etc.) if the start condition is satisfied. Then, when the control target value is determined, a command signal is output to an actuator (a control valve, a pump, and the like, which will be described later) in order to realize the control target value. As described above, over time, “the establishment of the start condition” and “the determination of the control target value”
And “output of actuator command signal” are performed in that order. Then, in this brake device, if "when the pressure increase control is started" is defined as when the start condition is satisfied, "before the pressure increase control is started" means before the start condition is satisfied, and , "At the start of pressure increase control"
Is defined as the time when the control target value is determined, "before start of pressure increase control" means before determination of the control target value, and "when start of pressure increase start" is instructed. If it is defined as when the signal is output, “before the pressure increase control is started” means before the output of the actuator command signal. When any of the definitions is adopted, “before the pressure increase control” in this brake device means before the output of the actuator command signal.

(2) The first pressure increasing control device determines a pressure increasing amount of the brake cylinder fluid pressure with respect to the master cylinder fluid pressure according to a target deceleration gradient based on the pre-control deceleration gradient. The brake device according to the above mode (1), including a pressure determining means (claim 2). In this brake device, during the pressure increase control, the pressure increase amount of the brake cylinder pressure relative to the master cylinder pressure is determined. Therefore, according to this brake device, the boosting amount is easily determined according to the target deceleration gradient based on such knowledge, so that the design of the boosting control device (in particular, the design of software) can be simplified easily. The effect of obtaining is obtained.

(3) The first pressure increasing amount determining means, at each time during the pressure increasing control, determines the value of the product of the time elapsed from the start of the pressure increasing control and the target deceleration gradient. The brake device according to item (2), including means for determining a pressure increase amount (claim 3). According to this brake device, the product of the elapsed time from the start of the pressure increase control and the target deceleration gradient is used as the time integral value of the target deceleration.
The effect is obtained that one embodiment of the brake device described in the section is provided.

(4) In the pressure increase control, in the pressure increase control, the control deceleration gradient which is the deceleration gradient acquired by the deceleration gradient acquisition means during the pressure increase control and the pre-control deceleration gradient. A second step of determining a pressure increase amount of the brake cylinder hydraulic pressure with respect to the master cylinder hydraulic pressure based on a difference from the target deceleration gradient based on the speed gradient such that the deceleration gradient during control becomes equal to the target deceleration gradient. The brake device according to item (1), including a pressure increase amount determining means (claim 4). In this brake device, during the pressure increase control, the amount of pressure increase is determined in consideration of both the target deceleration gradient based on the pre-control deceleration gradient and the control deceleration gradient. , The temporal change gradient of the master cylinder hydraulic pressure during the pressure increase control is reflected. Therefore, according to this brake device, since the pressure increase amount is determined in consideration of the temporal change gradient of the master cylinder hydraulic pressure during the pressure increase control, the effect that the target deceleration gradient is accurately realized is obtained. Can be

(5) A brake operation state quantity-related quantity sensor for detecting a quantity directly related to the operation state quantity of the brake operation member, wherein the pressure increase control device comprises: (a) the pre-control deceleration. First control means for controlling the height of the brake cylinder hydraulic pressure based on the gradient; and (b) based on a brake operation state amount-related amount detected by the brake operation state amount-related amount sensor during the pressure increase control. (C) when the brake operation state quantity-related amount sensor is normal, the second control means is selectively operated, and when abnormal, the second control means controls the height of the brake cylinder hydraulic pressure. 1
The brake device according to any one of (1) to (4), further including a selection device for selecting and operating the control device (claim 5). In this brake device, the pressure increase control is executed by using the brake operation state amount-related amount sensor when the sensor is normal, and is executed by using the deceleration gradient acquisition unit when it is abnormal. Therefore, according to this brake device, unless both the brake operation state quantity related amount sensor and the deceleration gradient acquisition unit become abnormal, the pressure increase control can be executed, and the reliability against the failure of the brake device is improved. The effect is obtained.

(6) The deceleration gradient acquiring means includes: (a) a vehicle deceleration sensor for detecting the vehicle deceleration; and (b) a plurality of vehicle decelerations sequentially detected by the vehicle deceleration sensor. The brake device according to any one of (1) to (5), further comprising: a calculating means for calculating the deceleration gradient based on the calculated value.
In this brake device, the “vehicle deceleration sensor” is configured to directly detect the vehicle deceleration, or indirectly as a temporal change gradient of the estimated vehicle speed based on the wheel speeds of a plurality of wheels in the vehicle, as described later. It can be in the form of detection.

(7) The calculating means is based on a plurality of vehicle decelerations sequentially detected by the vehicle deceleration sensor from immediately after the start of a series of operations of the brake operation member to immediately before the start of the pressure increase control. (6) The brake device according to the above mode (6), further comprising: means for calculating the pre-control deceleration gradient.

(8) The calculating means is configured to provide the provisional deceleration gradient based on a plurality of vehicle decelerations sequentially detected by the vehicle deceleration sensor sequentially immediately after the start of a series of operations of the brake operation member. The provisional deceleration gradient obtained before the start of the pressure increase control and when the vehicle body deceleration detected by the vehicle body deceleration sensor reaches a reference value is calculated as the pre-control deceleration. Includes gradient means
The brake device according to (6).

(9) The calculating means is configured to provide the provisional deceleration gradient based on a plurality of vehicle decelerations sequentially detected by the vehicle deceleration sensor sequentially immediately after the start of a series of operations of the brake operating member. (6) The brake device according to the above mode (6), further comprising means for calculating the temporary deceleration gradient obtained immediately before the start of the pressure increase control and setting the provisional deceleration gradient as the pre-control deceleration gradient.

(10) Further, a booster is provided between the brake operating member and the master cylinder and assists the operating force of the brake operating member and transmits the same to the master cylinder. The brake device according to any one of (1) to (10), which is established when the assisting limit is reached.

(11) Further, a booster is provided between the brake operating member and the master cylinder and assists the operating force of the brake operating member and transmits it to the master cylinder. That is, when the boosting limit is reached, the pressure increase control device,
The brake device according to any one of (1) to (10), further including target deceleration gradient determining means for determining the target deceleration gradient as the pre-control deceleration gradient (Claim 6). According to this brake device, the vehicle body deceleration changes with time at substantially the same gradient regardless of before and after the booster assist limit, so that the braking effect is stabilized and the brake operation feeling is improved. .

(12) The vehicle further includes a vehicle deceleration sensor for detecting the vehicle deceleration, and the start condition is satisfied when the vehicle deceleration detected by the vehicle deceleration sensor reaches a reference value ( The brake device according to any one of (1) to (11). According to this brake device, the necessity determination of the pressure increase control and the control of the brake cylinder fluid pressure in the pressure increase control can be executed using a common sensor, and the number of sensors in the brake device can be reduced. Is obtained.

(13) Further, (a) a booster provided between the brake operating member and the master cylinder for assisting the operating force of the brake operating member and transmitting it to the master cylinder; (12) The brake device according to (12), further including a vehicle body deceleration sensor for detecting a speed, wherein the reference value is set to a value at which the vehicle body deceleration is expected to be taken when the booster assist limit is reached. According to this brake device, since the brake cylinder hydraulic pressure is made higher than the master cylinder hydraulic pressure after the booster assist limit, a large wheel braking force can be obtained despite the booster assist limit.

(14) The vehicle has a plurality of the wheels, and the brakes are provided on each of the plurality of wheels. The brake device further includes a slip for each of the plurality of wheels. (A) a plurality of wheel speed sensors that detect the rotational speed of each of the plurality of wheels, and (b) a plurality of wheel speed sensors that are detected by the plurality of wheel speed sensors (C) calculating a plurality of wheel speeds detected by the plurality of wheel speed sensors and the estimated vehicle speed calculating means; A wheel slip control device having a brake control device for controlling each of the brakes based on the estimated vehicle speed. The vehicle body deceleration calculating means for calculating the vehicle body deceleration as a temporal change gradient of a constant vehicle speed includes (1)
The brake device according to the item (2) or (13). In this brake device, a plurality of wheel speed sensors and an estimated vehicle speed calculating means are shared by the pressure increase control device and the wheel slip control device. Therefore, according to this brake device, it is not necessary to provide dedicated hardware for obtaining the deceleration gradient, and the effect that the cost increase for realizing the pressure increase control can be reduced can be obtained. In this brake device, the "wheel slip control device" includes, for example, an anti-lock control device that prevents the locking tendency of each wheel from becoming excessive during braking of the vehicle, and a spin tendency of each wheel that becomes excessive when driving the vehicle. There is a traction control device to prevent.

(15) The pressure increase control device is: (a) a first state provided in the middle of the fluid passage and allowing 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 at least a second state that blocks the flow of hydraulic fluid from the brake cylinder to the master cylinder; and (b) a part of the liquid passage between the control valve and the brake cylinder. A pump connected to the discharge side to pump hydraulic fluid from the suction side and discharge the hydraulic fluid to the discharge side; the control valve and the pump jointly control the amount of increase in the brake cylinder pressure relative to the master cylinder pressure; (1) to control the height of the brake cylinder hydraulic pressure
The brake device according to any one of the above (14).

(16) The control valve is a pressure control valve provided in the liquid passage, and in a state where the hydraulic fluid is discharged from the pump, the second hydraulic pressure closer to the brake cylinder than the pressure control valve is provided. Is higher than the first hydraulic pressure on the master cylinder side, but if the difference is equal to or less than the boosting amount, the state is switched to the second state, the second hydraulic pressure is higher than the first hydraulic pressure and the difference is higher than the boosting amount. (15) includes a pressure control valve that controls the second hydraulic pressure to be higher than the first hydraulic pressure and to make the difference equal to the pressure increase amount by switching to the first state if the pressure is to be increased. The brake device as described. According to this brake device, since the height of the brake cylinder hydraulic pressure is relatively controlled based on the master cylinder hydraulic pressure, the brake cylinder can be operated according to the master cylinder hydraulic driver's intention even if the pressure increase amount is the same. The effect is obtained that the hydraulic pressure changes and the driver's intention is easily reflected in the height of the brake cylinder hydraulic pressure.

(17) The pressure control valve controls the flow state of the hydraulic fluid between the master cylinder side and the brake cylinder side in the liquid passage, and at least the valve element and the valve seat. On the other hand, there is provided a magnetic force generating means for generating a magnetic force acting to control the relative movement between the valve element and the valve seat, and the electromagnetic pressure in which the pressure increase amount changes based on the magnetic force. The brake device according to mode (16), including a control valve, wherein the pressure increase control device includes a magnetic force control device that controls the magnetic force to change the pressure increase amount. According to this brake device, there is obtained an effect that one embodiment of the brake device described in the above mode (16) is provided.

(18) In the pressure-increasing control, the pressure-increasing control device controls the deceleration gradient during control, which is the deceleration gradient acquired by the deceleration gradient acquiring means during the pressure-increasing control, and the pre-control deceleration. The brake device according to claim 1, further comprising third pressure increasing amount determining means for determining an increasing amount of the brake cylinder hydraulic pressure with respect to the master cylinder hydraulic pressure based on the speed gradient.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some specific embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a brake device according to an embodiment of the present invention. This brake device is mounted on a four-wheeled vehicle and includes a vacuum booster as a booster for assisting a pedal depression force.

This brake device further includes an antilock control device and a pressure increase control device. The anti-lock control device is, as an example of a wheel slip control device, a device that prevents an excessive tendency of locking of each wheel 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, in consideration of the fact that the vacuum booster has an assisting limit, the pressure increase control device considers that the vehicle deceleration has an ideal gradient with respect to the pedal depression force during vehicle braking (for example, before and after the assisting limit of the vacuum booster) This is a device that controls the braking effectiveness characteristic, which is the relationship between the pedal depression force and the vehicle deceleration, so that the pressure is increased (almost at the same gradient). This pressure increase control device operates using the pump. That is, the pump is shared by the antilock control device and the pressure increase control device.

In the drawing, reference numeral 10 denotes a brake pedal as a brake operating 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 is well known, the booster 12 is a power piston based on a differential pressure between a negative pressure chamber that is always in communication with a negative pressure source and a variable pressure chamber that is selectively connected to the negative pressure chamber and the atmosphere. Assists pedal effort based on power. The master cylinder 14 is, as is well known, a tandem type in which two pistons are slidably fitted in series with each other in a housing, and the two pistons are activated based on the output of the booster 12. By doing so, a hydraulic pressure having the same height is generated in each of the pressurizing chambers formed in front of each of the pistons. A brake cylinder for operating the brake of the front left wheel FL and a brake cylinder for operating the brake of the rear right wheel RR are connected to one pressurizing chamber, and a brake cylinder for operating the brake of the front right wheel FR is connected to the other pressurizing chamber. And a brake cylinder for operating the brake of the left rear wheel RL. 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.

The master cylinder 14 is connected to the brake cylinder 20 of the left front wheel FL and the brake cylinder 20 of the right rear wheel RR via a main passage 18. Main passage 1
Reference numeral 8 denotes a bifurcated branch after extending from the master cylinder 14, and one main passage 24 and two branch passages 26 are connected to each other. Each brake cylinder 20 is connected to the tip of each branch passage 26.

A pressure control valve 30 is provided in the main passage 24 as a control valve. The pressure control valve 30 controls the hydraulic pressure on the brake cylinder 20 side in the main passage 18 relatively to the hydraulic pressure on the master cylinder 14 side. Specifically, the hydraulic fluid is discharged from the pump 40. In this state, if the brake cylinder hydraulic pressure is higher than the master cylinder hydraulic pressure but the differential pressure is equal to or less than the target differential pressure (target pressure increase amount), the flow of the hydraulic fluid from the pump 40 to the master cylinder 14 is blocked. If the brake 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 pump 40
By permitting the flow of the working fluid toward 4, the brake cylinder fluid pressure is controlled to be higher than the master cylinder fluid pressure and the differential pressure thereof becomes the target differential pressure.

In the present embodiment, the pressure control valve 30 is of a type that electromagnetically controls the pressure difference between the brake cylinder 20 and the master cylinder 14. Specifically, as shown in FIG. 2, the pressure control valve 30 includes a housing (not shown) and a valve 70 for controlling the flow state of the hydraulic fluid between the master cylinder side and the brake cylinder side in the main passage 18. 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 30, in a non-operating state (OFF state) where the solenoid 74 is not excited,
The valve 70 is separated from the valve seat 72 by the elastic force of the spring 76, thereby allowing bidirectional flow of the hydraulic fluid between the master cylinder side and the brake cylinder side in the main passage 18, and as a result, 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 30 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 operation state (O) in which the solenoid 74 is excited
N state), the discharge pressure of the pump 40,
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 40 is seated on the valve seat 72,
Escape to the Linda 14 is prevented, and the discharge of the pump 40
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 40, that is, the brake cylinder fluid pressure is further increased.
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 40 is
Is released to the master cylinder 14, and as a result, the pump 4
The discharge pressure of 0, that is, the brake cylinder fluid pressure further increases
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 30 is arranged such that the magnitude of the solenoid attraction 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 30 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 30 is closed by the fluid force generated in the movable member in the pressure control valve 30 when the brake pedal 10 is depressed, the flow of the hydraulic fluid from the master cylinder 14 to the brake cylinder 20 is ensured. To do that. The pressure control valve 30 is further provided with a relief valve 86 in parallel with it. This is to prevent the discharge pressure of the pump 40 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 26. 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 26 between the pressure booster valve 90 and the brake cylinder 20, and 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 reservoir passage 96, and realizes a reduced pressure state in which the flow of hydraulic fluid from the brake cylinder 20 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 40, and the discharge side of the pump 40 is connected by a discharge passage 114 to a portion of the main passage 18 between the pressure control valve 30 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 restrictor and a fixed damper 122, respectively, so that pulsation of the pump 40 is reduced.

During the pressure increase control, the pump 40 pumps up the hydraulic fluid from the reservoir 98 and discharges the hydraulic fluid to each brake cylinder 20 to increase the pressure in each brake cylinder 20. Unless the lock control is being executed, there is usually no hydraulic fluid to be pumped into the reservoir 98. To ensure that the pressure increase control is executed, regardless of whether the antilock control is executed, Needs to be replenished with hydraulic fluid. Therefore, in the present embodiment, the main passage 24
A supply passage 130 extending from a portion between the master cylinder 14 and the pressure control valve 30 and reaching the reservoir 98 is provided.

However, since the master cylinder 14 and the reservoir 98 are always in communication with each other through the supply passage 130, even if the brake pedal 10 is depressed,
The master cylinder 14 cannot be pressurized unless the reservoir piston 104 bottoms in the reservoir 98,
The braking effect is delayed. Therefore, the supply passage 13
An inflow control valve 140 is provided in the middle of zero.

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 of a pilot control type, and controls the inflow of the hydraulic fluid to the reservoir 98 in cooperation with the reservoir piston 104. Therefore, the reservoir 98 is configured as follows. That is, when the volume of the reservoir chamber 106 increases from the normal value, the reservoir piston 1
04 from the normal position to the volume increasing position,
Is reduced from the normal value, the reservoir piston 104 is displaced from the normal position to the volume reduction position. The normal position of the reservoir piston 104 is to bias the reservoir piston 104 toward the reduced volume position via the retainer 144 by the spring 108, while the retainer 144 is in the normal position when the reservoir piston 104 is in the normal position. , And when the volume of the reservoir chamber 106 decreases from the normal value, the reservoir piston 104
Moves independently from the normal position, and conversely, the reservoir 106
If the volume of the reservoir piston increases from the normal value, the reservoir piston 10
4 is the spring 10 together with the retainer 144 from the normal position.
Move backward while compressing 8.

The inflow control valve 140 is moved from the reservoir 98 to the master cylinder 14 by a valve 150 and a valve seat 152.
A check valve 160 which allows the flow of the hydraulic fluid toward the flow direction but prevents the flow in the opposite direction, and a valve 150 with a valve seat 152.
And a valve opening member 162 for forcibly opening the check valve 160 by separating the check valve 160 from the valve. The valve-opening member 162 is linked to the reservoir piston 104. When the reservoir piston 104 is in the normal position, the valve-opening member 162 does not come into contact with the valve 150, whereas the reservoir chamber 106 Of the reservoir piston 104
When advancing from the normal position, abuts on the valve 150,
The check valve 160 is forcibly opened. By this opening, the flow of the hydraulic fluid from the master cylinder 14 toward the reservoir 98 is allowed, and the hydraulic fluid is supplied to the reservoir chamber 106 from the master cylinder 14. The inflow control valve 14
0 is shown in FIG. 2 to open slightly when the reservoir piston 104 is in the normal position,
It is possible to design to close.

FIG. 4 shows an electrical configuration of the brake device. The brake device is a CPU, ROM and R
An electronic control unit (ECU) 200 mainly including a computer including an AM is provided. Various routines including a pressure increase control routine (shown in flowcharts in FIGS. 5 and 6), an antilock control routine (not shown), and an estimated vehicle speed calculation routine (not shown) are stored in the ROM. When these routines are executed by the CPU while using the RAM, the pressure increase control and the antilock control are respectively executed.

A brake switch 201, a master cylinder hydraulic pressure sensor 202, and a wheel speed sensor 204 are connected to the input side of the ECU 200. The brake switch 201 detects depression of the brake pedal 10 as a brake operation, and outputs a brake operation signal indicating the presence or absence of a brake operation. Master cylinder pressure sensor 202
Detects the master cylinder fluid pressure and outputs a master cylinder fluid pressure signal that defines the height of the master cylinder fluid pressure.
The wheel speed sensor 204 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 40 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 30.
The solenoids 212 of the solenoid 74, the inflow control valve 140, the pressure increasing valve 90, and the pressure reducing valve 100 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 30, while the solenoid 212 is turned on for each of the solenoids 212 of the pressure increasing valve 90 and the pressure reducing valve 100.
An ON / OFF drive signal for performing the / OFF drive is output.

Here, the pressure increase control by the ECU 200 will be described in detail.

When the pedaling force F of the brake pedal 10 increases to a certain value, the pressure in the variable pressure chamber rises to the atmospheric pressure and the booster 12 reaches the assisting limit. After the assisting limit, the booster 12 cannot assist the pedaling force F. Therefore, if no countermeasures are taken, as shown in the graph of FIG. brake cylinder pressure level of P _B that is lower than the height of the brake cylinder pressure P _B when it is assumed that there is no boosting limit. Focusing on this fact, the pressure increase control is performed.
As graphically represented in, when the booster 12 has reached the boosting limit, the pressure-increasing control start condition is satisfied, then the pump 40 is operated master cylinder pressure P _M from the differential pressure [Delta] P ( the master cylinder fluid increasing relative pressure P _M pressure amount) by high liquid pressure of the brake cylinder pressure P _B is generated in the brake cylinder 20, thereby either before or after the boosting limit of the booster 12, to stabilize the braking effectiveness .

In this embodiment, the target differential pressure ΔP is
For example, as shown in the graph of FIG. 9, the pressure is determined according to the master cylinder pressure P _M ,
_M is detected by the master cylinder pressure sensor 202. However, the master cylinder hydraulic pressure sensor 202 is not always normal and may be abnormal for some reason.

On the other hand, the effectiveness of the brake is generally expressed as the relationship between the pedal depression force F and the vehicle body deceleration G. However, when the brake pedal 10 is strongly depressed so that the booster 12 reaches the assisting limit, the pedal depression force F tends to increase with time, and therefore,
Taking this into account, the effectiveness of the brake can be expressed as a relationship between the time and the vehicle body deceleration G. Here, the relationship can be expressed as a deceleration gradient S that is a temporal change gradient of the vehicle body deceleration. Therefore, in order to stabilize the braking effect regardless of before and after the assist limit, the target differential pressure ΔP may be determined so that the deceleration gradient becomes substantially equal before and after the assist limit.

The target differential pressure ΔP can be determined according to the following principle. After the assisting limit, the brake cylinder hydraulic pressure P _B is represented by P _B = P _M + ΔP, and the deceleration gradient S at that time is represented by a change ΔP _B of the brake cylinder hydraulic pressure P _B per fixed time. Proportional. Further, it can be considered that generally after boosting limit, small temporal change gradient of the master cylinder pressure P _M. Therefore, after the assisting limit, it can be considered that the deceleration gradient S is proportional to the variation ΔΔP of the differential pressure ΔP per fixed time. Further, as shown in FIG.
_{At (0)} , the pressure increase control is started, and at that time, the differential pressure Δ
Since P is 0, the differential pressure ΔP ₍₁₎ to be realized at the time t ₍₁₎ in order to realize the deceleration gradient S is expressed by ΔP ₍₁₎ = K _P · _ST · T ₍₁₎ Can be. Here, K _P : proportionality constant T ₍₁₎ : elapsed time from time t _{( 0)} to time t ₍₁₎ Therefore, the differential pressure ΔP to be realized at each time t _(n)
Can be expressed by a general formula of ΔP _(n) = K _P · S · T _(n) . Here, T _(n) : elapsed time from time t _{( 0)} to time t _(n)

Based on the above findings, in the present embodiment, the rules for determining the target differential pressure ΔP are made different between the case where the master cylinder hydraulic pressure sensor 202 is normal and the case where it is abnormal. In some cases, the target differential pressure ΔP is determined according to the master cylinder pressure P _M detected by the master cylinder pressure sensor 202, whereas when the master cylinder pressure sensor 202 is abnormal, ,
Deceleration slope S _P before the start of the pressure increasing control is obtained as a control before deceleration slope S _P, and, together with the pre-control deceleration slope S _P is used as the target deceleration slope S _D, the target deceleration The target differential pressure ΔP is determined according to the gradient _SD , specifically, according to the product of the target deceleration gradient _SD and the elapsed time T _(n) .

Here, the “pre-control deceleration gradient S _P ” can be obtained in various modes. For example, as shown in FIG. 11, a pre-control deceleration gradient _SP is acquired using a plurality of vehicle body decelerations G detected in order from immediately after the start of the brake operation to immediately before the start condition of the pressure increase control is satisfied. be able to. In the present embodiment, “at the start of the pressure increase control” is the pump motor 210 that drives the pump 40 as an actuator.
Is defined as when the drive signal is first output, and “immediately before the start condition of the pressure increase control” in the above-described gradient acquisition mode means a time before “at the time of start of the pressure increase control”. Will be.

In this gradient acquisition mode, the “pre-control deceleration gradient _SP ” is, specifically, a plurality of vehicle decelerations detected in order from immediately after the start of the brake operation to immediately before the start condition of the pressure increase control is satisfied. it can be acquired control before deceleration slope S _P as the slope of the straight line in the case of approximating the velocity G in a straight line. The straight line, for example, can be determined by a method of obtaining a primary regression line, in this case, it is possible to gain control before deceleration slope R _P as the slope of the primary regression line.

In this gradient acquisition mode, the "pre-control deceleration gradient _SP " indicates a plurality of vehicle body decelerations G immediately after the start of the braking operation and immediately before the start condition of the pressure increase control is satisfied. deceleration acquired sample values of the gradient S, it is also possible to acquire the pre-control deceleration slope S _P as they acquired average value of the plurality of sample values S based on.

[0059] Further, as shown in FIG. 12, sequentially from immediately after the start of the braking operation, deceleration obtains a provisional value S _P output slope S, provisional decrease obtained in established immediately before or after the pressure increase control start condition The speed gradient _{SP is changed} to the final deceleration gradient S before control.
It can also be obtained as _P. Here, “immediately after the start condition of the pressure increase control is satisfied” means a time slightly before “at the time of start of the pressure increase control”.

[0060] Further, as shown in FIG. 13, sequentially from immediately after the start of the braking operation, it obtains the provisional value S _P output deceleration slope S, the vehicle deceleration G is obtained when it reaches the reference value G ₀ it is also possible to obtain the provisional deceleration slope S _P as a final control prior to the deceleration gradient S _P. Here, "reference value G
“ ₀ ” is set as a value that the vehicle body deceleration G is expected to take before the start condition of the pressure increase control is satisfied.

In the present embodiment, as shown in FIGS. 11 to 13, the obtained pre-control deceleration gradient _SP is directly used as the target deceleration gradient _SD to be realized in the pressure increase control. The target differential pressure ΔP is increased so that the vehicle body deceleration G increases at the gradient. As a result, the vehicle body deceleration G is increased at the same gradient regardless of before and after the boosting limit of the booster 12.

FIG. 14 shows how the temporal change gradient of the target differential pressure ΔP during the pressure increase control changes according to the target deceleration gradient _SD . During the pressure increase control, the target differential pressure ΔP
With time t, when the pre-control deceleration gradient S _P is large and the target deceleration gradient S _D is large, compared to when the pre-control deceleration gradient S _P is small and the target deceleration gradient S _D is small, It can be increased with a steep slope.

The details of the above-described pressure increase control will be specifically described with reference to the pressure increase control routines shown in FIGS.

This routine is repeatedly executed after the driver operates the ignition switch from the OFF position to the ON position. At the time of each execution, first, step S
1 (hereinafter simply referred to as “S1”; the same applies to the other steps), there is an abnormality in the master cylinder hydraulic pressure sensor 202 (in the figure, represented as “M / C hydraulic pressure sensor”). Is determined. For example, whether or not a disconnection or short circuit has occurred in the master cylinder hydraulic pressure sensor 202, the value detected by the master cylinder hydraulic pressure sensor 202 regardless of whether a brake operation has been detected by the brake switch 201, or not. whether such P _M indicates that it is not 0 is determined.

Assuming that there is no abnormality in the master cylinder pressure sensor 202 this time, the determination in S2 is NO, and the determination in S2 is NO.
At 3, a master cylinder pressure signal (represented by “M / C pressure signal” in the figure) is taken from the master cylinder pressure sensor 202. Thereafter, in S4, the master cylinder pressure P _M represented by the master cylinder hydraulic pressure signal whether higher than the reference value P _M0 is determined. It is determined whether or not the condition for starting the pressure increase control is satisfied. Here, the “reference value P _M0 ” is
There has been set to the height of the master cylinder pressure P _M when reaching the boosting limit. This time, the master cylinder pressure P _M
Is not higher than the reference value _{PM0, the} determination is NO, and in S5, the solenoid 74 of the pressure control valve 30 is
A signal for turning it off is output to the pump motor 210, and a signal for turning it off is output to the pump motor 210. This completes one execution of this routine.

[0066] In contrast, when the master cylinder pressure P _M is higher than the reference value P _M0 is, YES next determination of S4, in S6, push increase the brake cylinder pressure P _B from the master cylinder pressure P _M A power amount, that is, a target pressure difference ΔP between the master cylinder 14 (indicated by “M / C” in the figure) and the brake cylinder 20 (indicated by “W / C” in the figure) is calculated. Master cylinder pressure P _M
And the relationship between the target differential pressure ΔP has stored in the ROM, a target differential pressure ΔP corresponding to the current value of the master cylinder pressure P _M is being calculated according to that relationship. As described previously, FIG. 9, an example of the relationship between the master cylinder pressure P _M and the target differential pressure ΔP is shown in the graph, this example, the target differential pressure ΔP is the master cylinder pressure P _This is an example of a case that changes linearly with respect to _M.

[0067] Here, "the relationship between the master cylinder pressure P _M and the target differential pressure ΔP" for example, master cylinder pressure P _M
Relationship between the amount of brake cylinder pressure P _B is decreased by the booster 12 has reached the boosting limit, i.e.,
The relationship can be set to represent the difference between the solid line graph and the broken line graph in FIG. With this setting, the amount should be reduced brake cylinder pressure P _B by the booster 12 reaches the boosting limit becomes be supplemented by the pump 40, the assisting of the booster 12 in order to increase the servo ratio of the booster 12 its influence becomes the limit point is lowered requires not appear in the brake cylinder pressure P _B, while improving the braking effectiveness brake operation feeling is maintained well.

Thereafter, in S7, a current value I to be supplied to the solenoid 74 of the pressure control valve 30 is calculated according to the calculated 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 stored in accordance with the relationship.
Is calculated. Subsequently, in S8, a current is supplied to the solenoid 74 of the pressure control valve 30 with the calculated solenoid current value I, whereby current control is performed. Thereafter, in S9, a signal for turning on the pump motor 210 is output to the pump motor 210.
The hydraulic fluid is pumped from the reservoir 98, hydraulic fluid is discharged to each brake cylinder 20, thereby, the master cylinder pressure from the master cylinder pressure P _M P _M
Is generated in each brake cylinder 20 by a height corresponding to the height. This completes one execution of this routine.

The case where there is no abnormality in the master cylinder pressure sensor 202 has been described above. However, if there is an abnormality, the determination in S2 becomes YES, and the process proceeds to S10 and subsequent steps. In S10, the vehicle body deceleration G is calculated. In this embodiment, by executing the antilock control routine, it is determined that the largest one of the four wheel speeds is closest to the true vehicle speed based on the wheel speeds of the respective wheels detected by the wheel speed sensors 204. The estimated vehicle speed is calculated using the fact, and in S10, the vehicle body deceleration G is calculated as a time differential value of the estimated vehicle speed. FIG. 15 is a functional block diagram showing a process from the detection of the wheel speed to the calculation of the vehicle body deceleration G. The output side of the wheel speed sensor 204 of each wheel is connected to the input side of the estimated vehicle speed calculation means 220, and the output side of the estimated vehicle speed calculation means 220 is connected to the input side of the vehicle body deceleration calculation means 222. The part of the ECU 200 that executes S10 corresponds to the vehicle body deceleration calculating means 222. That is, in the present embodiment, the vehicle body deceleration calculating means 222 constitutes an example of a “vehicle deceleration sensor”.

Next, in S11, it is determined whether or not the pressure increase control should be started. In the present embodiment, it is determined whether or not the booster 12 has reached the assisting limit. Specifically, the brake operation is detected by the brake switch 201, and the vehicle body deceleration G is determined by the booster 12 It is determined whether or not a reference value G ₁ (> reference value G ₀ ) that is expected to be taken when reaching the assisting limit is exceeded. That is, in this embodiment, includes pressure increase control start condition is a first condition that the brake operation is detected by the brake switch 201, and a second condition that the vehicle deceleration G exceeds the reference value G ₁ When the first and second conditions are satisfied at the same time, it is determined that the booster 12 has reached the assisting limit.

This time, whether a brake operation is detected or not
Alternatively, even if the brake operation is detected, the vehicle deceleration G
There Assuming does not exceed the reference value G _1, not satisfied start condition is determined in S12 shifts NO, the S5. In contrast, this time, the brake operation is detected,
And, assuming that the vehicle deceleration G has exceeded the reference value G _1, the starting condition is satisfied, the determination of S12 YES next, in S13, the sensor abnormality control is performed.

FIG. 6 is a flowchart showing the details of step S13 as a sensor abnormality control routine. First, in S101, a pre-control deceleration gradient _SP is calculated based on the calculated plurality of vehicle decelerations G according to any of the above-described gradient acquisition modes, and the pre-control deceleration gradient _SP is set to the target deceleration. The gradient is set to _SD . Next, in S102, the elapsed time from the pressure increase control at the beginning t ₍₀₎ to the present time t _(n) T _(n) is calculated. Thereafter, in S103, a solenoid current value I _(n) is calculated based on the target deceleration gradient _SD and the elapsed time T _(n) . Specifically, it is calculated by the following equation: I _(n) = K _I · S _D · T _(n) "K _I" here is a proportionality constant. Subsequently, in S104, current control for the solenoid 74 of the pressure control valve 30 is performed using the solenoid current value I _(n) .

Thereafter, in S14 of FIG. 5, the pump motor 210 is turned on. This completes one execution of this routine.

After the start condition of the pressure increase control is satisfied and the pressure increase control is started, the depression of the brake pedal 10 is released, and if this is detected by the brake switch 201, the determination in S12 becomes NO, and In S5, pressure increase control end processing is performed. As described above, the brake switch 201 is provided to detect the driver's brake ending operation of releasing the depression of the brake pedal 10 to end the pressure increase control when the pressure increase control becomes unnecessary. Moreover, in this embodiment,
The start condition and the end condition of the pressure increase control have the same contents. However, the pressure-increasing control start condition is satisfied when a vehicle deceleration G has exceeded the reference value G _0, the termination condition,
The start condition and the end condition can be different from each other such that the condition is satisfied when the brake switch 201 detects that the brake pedal 10 is released from being depressed.

In the anti-lock control routine, while the wheel speed sensor 204 monitors the wheel speed and the vehicle speed of each wheel, the pressure increasing valve 90 is opened and the pressure reducing valve 100 is closed. By selectively realizing a depressurized state in which the pressure reducing valve 100 is closed and a pressure increasing state in which the pressure increasing valve 90 is closed, the wheels are prevented from being locked during vehicle braking. Further, the anti-lock control routine activates the pump motor 210 during the anti-lock control and causes the pump 40 to operate the reservoir 9.
The hydraulic fluid is pumped up from 8 and returned to the main passage 18.

This antilock control routine is executed regardless of whether or not the pressure increase control routine is executed. Therefore, when the pressure increase control is being performed and the locking tendency of each wheel is excessive, the antilock control routine is executed, and as a result, the brake operating force of each wheel does not need to be excessive.

As is apparent from the above description, according to the present embodiment, even if an abnormality occurs in the master cylinder hydraulic pressure sensor 202, the pressure increase control is performed, so that the reliability against the failure of the brake device is improved. The effect is obtained.

Further, in the present embodiment, when the abnormality occurs in the master cylinder hydraulic pressure sensor 202, the pressure increase control which is executed by using the deceleration gradient is performed by changing the vehicle deceleration G before the start thereof. That is, the brake pedal 1
This is performed in consideration of the zero depression situation. Therefore,
According to the present embodiment, after the pressure increase control is started, the vehicle body deceleration G
Shortage, and a sudden change in the vehicle deceleration G before and after the pressure increase control is prevented, and a decrease in the braking performance of the vehicle and a deterioration in the brake operation feeling due to the abnormality of the master cylinder hydraulic pressure sensor 202 are prevented. The effect is also obtained.

[0079] Further, in this embodiment, the pressure control valve 30 is a relative controlled to relatively control the height of the brake cylinder pressure P _B with respect to the master cylinder pressure P _M, the brake cylinders the height of the brake cylinder pressure P _B by only increasing the amount of the master cylinder pressure P _M of the hydraulic P _B is controlled is controlled to control the overall height of the brake cylinder pressure P _B compared to the case, there is also an effect that it becomes possible to accurately control the height of the brake cylinder pressure P _B by a simple technique.

[0080] Further, in the present embodiment, since the pressure control valve 30 is relative-controlled as described above, the height of the master cylinder pressure P _M i.e. driver's intention easily brake cylinder pressure P _B The effect of being reflected in the information is also obtained.

Further, in the present embodiment, when the master cylinder hydraulic pressure sensor 202 is abnormal, the vehicle deceleration sensor, which is a common sensor for determining whether the pressure increase control is necessary and controlling the pressure increase amount in the pressure increase control, is used. Therefore, the effect of reducing the number of sensors in the brake device can be obtained as compared with the case of using different sensors.

As is clear from the above description, in the present embodiment, a part of the ECU 200 that executes S10 in FIG. 5 and a part of S101 in FIG.
_And a part for executing the _P calculation) constitutes an example of the “deceleration gradient acquisition means” in cooperation with each other,
The part that executes steps S102 and S103 of FIG. 6 in FIG.
The part that executes S102 to S104 in FIG. 6 of 200 forms an example of a “first control unit”, and the master cylinder hydraulic pressure sensor 202 is a “brake operation state quantity related quantity sensor”.
The part of the ECU 200 that executes S3 and S4 to S9 in FIG. 5 constitutes an example of a “second control unit”, and the part of the ECU 200 that executes S1 and S2 of the ECU 200 is a “selection unit”. Since an example is configured, and a part of the ECU 200 that executes a part of S101 in FIG. 6 (a part related to the calculation of the target deceleration gradient _SD ) forms an example of the “target deceleration gradient determining unit”. is there.

Another embodiment will be described. However, this embodiment is different from the previous embodiment only in the sensor abnormality control routine, and the other elements are common. Therefore, only the routine will be described in detail, and the description of the other elements will be omitted.

FIG. 16 is a flowchart showing a sensor abnormality control routine according to this embodiment. In this routine, first, in S201, the pre-control deceleration gradient _SP is calculated in the same manner as in the previous embodiment, and the pre-control deceleration gradient _SP is set as the target deceleration gradient _SD. . Next, in S202, during the execution of your current increase control, each time t _(n), computed plurality of vehicle deceleration gradient deceleration slope S is controlled in the deceleration based on the G S _A Is calculated as For example, each time t _(n)
A plurality of body setting decelerations G of the latest setting calculated sequentially for each
Is approximated by a straight line, the deceleration gradient S _A during control is calculated as the slope of the straight line. Thereafter, in S203, the solenoid current value I is set to the target deceleration gradient S _D.
Is calculated as an appropriate value to reduce the difference between and the control deceleration gradient S _A. For example, it is calculated by _{I (n) = K I ·} S D · T (n) + K I '· (S D -S A) becomes equation. Here the second term on the right side is a feedback term, "K _I '" in the term is a proportionality constant. Subsequently, in S204, current control for the solenoid 74 of the pressure control valve 30 is performed at the solenoid current value I _(n) . This completes one execution of this routine.

[0085] In the previous embodiments are pressure increase control using a deceleration slope S is an open loop, the pressure increase amount without considering the temporal change gradient of the master cylinder pressure P _M in the control of because There is determined, the height of the brake cylinder pressure P _B is changed by the change gradient. In contrast, in the present embodiment, pressure increase control using a deceleration slope S is the feedback type, increase and consequently considering change gradient of the master cylinder pressure P _M increase amount is determined Therefore, the effect is obtained that the target deceleration gradient _SD is accurately realized without being affected by the change gradient.

[0086] As apparent from the above description, in the present embodiment, related to the operation portion and S201 in part (pre-control deceleration slope S _P output 16 for executing S10 in out Figure 5 ECU200 And the part executing the part) constitute an example of “deceleration gradient acquisition means” in cooperation with each other.
The part of U200 that executes S202 and S203 in FIG. 6 constitutes an example of “second pressure increasing amount determining means”,
The part of U200 that performs S202 to S204 in FIG. 6 constitutes an example of a “first control unit”, the master cylinder hydraulic pressure sensor 202 constitutes an example of a “brake operation state quantity related amount sensor”, Of these, the part that executes S3 and S4 to S9 in FIG. 5 constitutes an example of a “second control unit”, and the part of the ECU 200 that executes S1 and S2 constitutes an example of a “selection unit”.
Of these, a part of the part that executes S201 in FIG. 16 (part related to the calculation of the target deceleration gradient _SD ) constitutes an example of “target deceleration gradient determining means”.

Although the embodiments of the present invention have been described in detail with reference to the drawings, various modifications may be made based on the knowledge of those skilled in the art without departing from the scope of the claims. Of course, 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 front sectional view for explaining the structure and operation of a pressure control valve 30 in FIG.

It is a graph showing the relationship between the solenoid excitation current I and the solenoid attractive force F ₁ at the pressure control valve of FIG. 3 FIG.

FIG. 4 is a block diagram showing an electrical configuration of the brake device.

FIG. 5 is a flowchart illustrating a pressure increase control routine stored in a ROM in FIG. 4;

FIG. 6 is a flowchart showing details of S13 in FIG. 5 as a sensor abnormality control routine.

FIG. 7 shows a pedal depression force F and a brake cylinder fluid pressure P _B in a general brake device having a vacuum booster.
6 is a graph showing a relationship with the graph.

FIG. 8 is a graph for explaining the principle of pressure increase control in the brake device according to the embodiment.

FIG. 9 shows a master cylinder hydraulic pressure P _{M in the} pressure increase control.
6 is a graph showing the relationship between the pressure difference ΔP between the master cylinder and the brake cylinder.

FIG. 10 is a graph showing a relationship between a time t, a target deceleration gradient _SD, and the differential pressure ΔP in the pressure increase control.

[11] before control in the pressure increase control deceleration slope S _P
6 is a graph for explaining one mode of acquiring the data.

12 is a graph for explaining another embodiment for obtaining the pre-control deceleration slope S _P.

13 is a graph for explaining still another embodiment for obtaining the pre-control deceleration slope S _P.

FIG. 14 is a graph for explaining how the temporal change gradient of the differential pressure ΔP changes according to the target deceleration gradient _SD in the embodiment.

FIG. 15 is a block diagram showing a principle of detecting a vehicle body deceleration G in the embodiment.

FIG. 16 is a flowchart illustrating a sensor abnormality control routine of a pressure increase control routine in a brake device according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 brake pedal 12 vacuum booster 14 master cylinder 20 brake cylinder 30 pressure control valve 40 pump 200 ECU 202 master cylinder fluid pressure sensor 204 wheel speed sensor 220 estimated vehicle speed calculating means 222 vehicle body deceleration calculating means

Claims (6)

[Claims] 1. A brake operating member, a master cylinder for generating a hydraulic pressure based on an operating force of the brake operating member, a brake for suppressing wheel rotation, and a hydraulic passage connected to the master cylinder by a hydraulic passage. A brake device that operates the brake based on a hydraulic pressure supplied from a passage; a deceleration gradient acquisition unit that acquires a deceleration gradient that is a temporal change gradient of a vehicle body deceleration; During the operation of the member, when the start condition is satisfied, pressure increase control for increasing the hydraulic pressure of the brake cylinder to a hydraulic pressure higher than the hydraulic pressure of the master cylinder is started. Later, based on the pre-control deceleration gradient which is the deceleration gradient acquired by the deceleration gradient acquisition means before the start of the pressure increase control. Braking device is characterized by providing a pressure increase control device for controlling the height of the brake cylinder pressure. 2. A first pressure increasing means for determining a pressure increasing amount of the brake cylinder pressure with respect to the master cylinder pressure according to a target deceleration gradient based on the pre-control deceleration gradient. 2. The brake device according to claim 1, further comprising a quantity determining means. 3. The pressure-increasing amount determining means, at each time during the pressure-increasing control, according to a product of an elapsed time from the start of the pressure-increasing control and the target deceleration gradient. 3. The brake device according to claim 2, further comprising means for determining a pressure amount. 4. The pressure increasing control device according to claim 1, wherein
Based on the difference between the control deceleration gradient, which is the deceleration gradient acquired by the deceleration gradient acquisition means during the pressure increase control, and the target deceleration gradient based on the pre-control deceleration gradient,
2. The brake according to claim 1, further comprising second pressure increasing amount determining means for determining an increasing amount of the brake cylinder hydraulic pressure with respect to the master cylinder hydraulic pressure so that the deceleration gradient during control becomes equal to the target deceleration gradient. apparatus. 5. A brake operation state quantity-related quantity sensor for detecting a quantity directly related to an operation state quantity of the brake operation member, wherein the pressure increase control device comprises: (a) the pre-control deceleration gradient; A first control means for controlling the height of the brake cylinder fluid pressure based on the brake operation state quantity based on the brake operation state quantity related amount detected by the brake operation state quantity related quantity sensor during the pressure increase control. (C) when the brake operation state quantity-related amount sensor is normal, the second control means is selectively operated, and when abnormal, the first control means controls the first cylinder pressure. 5. The brake device according to claim 1, further comprising a selection unit that selects and operates the control unit. 6. A booster provided between the brake operating member and the master cylinder for assisting the operating force of the brake operating member and transmitting the operating force to the master cylinder, wherein the start condition is such that the booster is assisted. The pressure increase control device includes target deceleration gradient determining means for determining the target deceleration gradient as the pre-control deceleration gradient, which is established when a limit is reached. The brake device according to item 1.