JP2000043691A - Brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve brake feeling of a brake device of hydraulic brake-by-wire type. SOLUTION: When depressing operation of a brake pedal 1 is conducted rapidly, flowing of brake fluid into a master cylinder hydraulic pressure sensor 6 is delayed by a restrictor 22 formed at the hydraulic pressure introduction passage 33 of the master cylinder hydraulic pressure sensor 6. As a result, a hydraulic pressure increase in the master cylinder hydraulic pressure sensor 6 is made so as to correspond to a hydraulic pressure increase in a stroke simulator 3, thereby attaining good brake feeling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic system for supplying brake fluid to a wheel brake based on an operation amount of a brake pedal. The present invention relates to an improvement of a so-called hydraulic brake-by-wire type brake device which is performed by a generation control device and generates a braking force corresponding to an operation amount of a brake pedal to a wheel brake.

[0002]

2. Description of the Related Art Conventionally, this type of hydraulic brake by
As a wire type brake device (hereinafter, referred to as "hydraulic BBW brake device"), there is one as shown in FIG.

In the hydraulic BBW brake system shown in FIG. 4, 1 is a brake pedal, 2 is a master cylinder connected to the brake pedal 1, and generates a brake fluid pressure based on the operation of the brake pedal 1. Is connected to the stroke simulator 3 via a flow path 31. The stroke simulator 3 accommodates the brake fluid output from the master cylinder 2 and allows the brake pedal 1 to be depressed, and applies a reaction force to the brake pedal 1 according to the depressing stroke of the brake pedal 1.

The output of the master cylinder 2 is passed through a flow path 32 in parallel with the stroke simulator 3.
It is also connected to the wheel brake 4. The wheel brake 4 generates a braking force on the wheels based on the hydraulic pressure of the supplied brake fluid.

A normally closed solenoid valve 5s and a normally open solenoid valve 5w are provided in the flow paths 31 and 32 as on-off valves, respectively. The normally closed solenoid valve 5s is provided between the master cylinder 2 and the stroke simulator 3. Distributes and shuts off the brake fluid,
The normally open solenoid valve 5w performs the flow and cutoff of the brake fluid between the master cylinder 2 and the wheel brake 4.

In order to detect the operation amount (for example, operation force, operation stroke) of the brake pedal 1 in the flow path 31m on the master cylinder 2 side with respect to the normally closed solenoid valve 5s,
A master cylinder hydraulic pressure sensor 6 for detecting the output hydraulic pressure of the master cylinder 2 is provided, and a hydraulic pressure generation control device 7 is connected to the flow passage 32w on the wheel brake 4 side with respect to the normally open solenoid valve 5w. ing.

The hydraulic pressure generation control device 7 is, for example, a hydraulic pressure supply source (not shown) for storing a boosted brake fluid without depending on the depression operation of the brake pedal 1, and in a state where the brake fluid is released. A reservoir (not shown) for storing, and a brake fluid supplied from the fluid pressure supply source to the wheel brake 4 for supplying boosted brake fluid or returning the brake fluid having a raised fluid pressure stored in the wheel brake 4 to the reservoir. The hydraulic pressure control valve (not shown) is provided.

The normally closed solenoid valve 5s, normally opened solenoid valve 5w,
The hydraulic pressure generation control device 7 includes a master cylinder hydraulic pressure sensor 6, a wheel brake hydraulic pressure sensor 8 for detecting the brake hydraulic pressure supplied to the wheel brake 4, and a brake lamp switch 9 provided on the brake pedal 1.
The operation is controlled by the brake control device 10 based on the output of.

When the brake pedal 1 is depressed, the brake control device 10 controls the brake lamp switch 9.
The normally closed solenoid valve 5s is opened and the normally opened solenoid valve 5w is opened based on the output of. Thus, the brake fluid discharged from the master cylinder 2 based on the depression operation of the brake pedal 1 is not supplied to the wheel brake 4 but is supplied to the stroke simulator 3 and the master cylinder hydraulic pressure sensor 6.

The brake control device 10 also controls the brake pedal based on the output hydraulic pressure of the master cylinder 2 detected by the master cylinder hydraulic pressure sensor 6 in conjunction with the operation of the normally closed solenoid valve 5s and the normally open solenoid valve 5w. A braking force generated by the wheel brake 4 corresponding to one operation amount (for example, a stroke) is obtained, and a brake fluid necessary for generating the braking force is determined by:
Each part of the hydraulic pressure generation control device 7 is controlled so as to be supplied not from the master cylinder 2 but from the hydraulic pressure generation control device 7 and supplied to the wheel brake 4. That is, the hydraulic pressure control valve of the hydraulic pressure generation control device 7 is drive-controlled based on the output of the wheel brake hydraulic pressure sensor 8, and the brake fluid boosted from the hydraulic pressure supply source is supplied to the wheel brake 4 and controlled. A braking force (generated braking force obtained in advance) corresponding to the amount of depression of the brake pedal 1 (for example, operating force, operating stroke) is generated in the wheel brake 4.

On the other hand, when the brake pedal 1 that has been depressed is released, the brake control device 10 controls the components of the hydraulic pressure generation control device 7 to conversely Decrease brake fluid pressure. That is, the hydraulic pressure control valve of the hydraulic pressure generation control device 7 is drive-controlled based on the output of the wheel brake hydraulic pressure sensor 8 to discharge the brake fluid in the wheel brake 4 to the reservoir. A braking force corresponding to the depression operation amount is generated.

When the brake control device 10 detects an abnormality such as an inability to supply a boosted brake fluid from the hydraulic pressure supply source of the hydraulic pressure generation control device 10, the brake control device 10 detects the output of the brake lamp switch 9 by detecting this abnormal state. The normally closed solenoid valve 5s and the normally opened solenoid valve 5w are not actuated as described above, and the brake fluid from the master cylinder 2 is supplied directly to the wheel brake 4 in the same manner as in a general brake device. , Causing the wheel brake 4 to generate a braking force.

[0013]

In a general brake device for directly supplying brake fluid from a master cylinder to a wheel brake, the effectiveness of the brake is insensitive to a transient hydraulic pressure fluctuation of the master cylinder. The main effect of the brake is the generation of hydraulic pressure at the wheel brake, and between the generated hydraulic pressure at the wheel brake and the amount of liquid sent from the master cylinder,
It is known that there is a correlation that hardly changes even during sudden braking. That is, the generated hydraulic pressure of the wheel brake is determined not by the transient hydraulic pressure of the master cylinder but by the amount of brake fluid sent from the master cylinder to the wheel brake, in other words, by the stroke amount of the master cylinder.

However, in contrast to the above-mentioned general brake device, in the above-mentioned hydraulic BBW brake device, the output hydraulic pressure of the master cylinder 2 is not directly supplied to the wheel brake 4 during normal operation, and the brake pedal 1 has an appropriate stroke. Is supplied through a flow path 31 to a stroke simulator 3 of a liquid amount absorption type for generating the pressure. Then, by detecting the output hydraulic pressure of the master cylinder 2 at that time by the hydraulic pressure sensor 6, the depression operation amount (for example, operation force, operation stroke) of the brake pedal 1 is indirectly detected, and the brake pedal 1 The braking force generated by the wheel brake 4 corresponding to the operation amount is obtained, and the brake fluid necessary for obtaining the generated braking force is supplied not from the master cylinder 2 but from the hydraulic pressure generation control device 7 to the wheel brake 4. Then, a braking force corresponding to the amount of depression of the brake pedal 1 is generated in the wheel brake 4.

In the above-described hydraulic BBW brake device, the output hydraulic pressure of the master cylinder 2 is controlled by the wheel brake 4.
The normally closed solenoid valve 5s is provided in the flow path 31 between the master cylinder 2 and the stroke simulator 3 so that the brake fluid that must be supplied to the wheel brake 4 by the stroke simulator 3 is not consumed in the event of abnormal supply to the wheel.
Is provided. Further, when the brake fluid is supplied from the fluid pressure generation control device 7 to the wheel brake 4 in a normal state, the boosted brake fluid pressure from the fluid pressure generation control device 7 is not applied to the master cylinder 2 side.
A normally open solenoid valve 5w is provided in a flow path 32 between the wheel brake 4 and the wheel.

Therefore, in contrast to the normally-closed solenoid valve 5s and the normally-open solenoid valve 5w, the master cylinder hydraulic pressure sensor 6 determines whether the driver intends to operate the brake pedal regardless of whether the brake control device 10 is in the open or closed state of the normally-closed solenoid valve 5s. In order to be able to always check, a normally closed solenoid valve 5s is provided in the flow path 31m on the master cylinder 2 side.

As a result, the above-mentioned hydraulic BBW brake device has the following problems.

That is, when the brake pedal 1 is suddenly depressed, even if the normally closed solenoid valve 5s provided in the flow path 31 is opened, the normally closed solenoid valve 5s in the opened state normally causes the throttle effect of the solenoid valve 5s itself. The inflow of the brake fluid based on the stroke of the master cylinder 2 into the stroke simulator 3 on the downstream side of the closed solenoid valve 5s is caused to flow to the flow path 31m on the upstream side of the normally closed solenoid valve 5s provided with the master cylinder fluid pressure sensor 6. Since the flow of the brake fluid is delayed, the magnitude of the hydraulic pressure in the flow path 31m on the master cylinder 2 side upstream of the normally-closed solenoid valve 5s sharply increases. In the stroke simulator 3 on the downstream side, the rise in hydraulic pressure is delayed more than in the flow path 31m.

For this reason, when the brake pedal 1 is suddenly depressed, the detection output of the hydraulic pressure sensor 6 increases once in response to the rapid increase in the hydraulic pressure in the flow path 31m, and then the hydraulic pressure of the stroke simulator 3 and the master cylinder 2 side channel 3
In response to the equilibrium with the hydraulic pressure of 1 m, a phenomenon occurs in which the output of the master cylinder hydraulic pressure sensor 6 that has increased sharply decreases.

Due to this phenomenon, in the conventional hydraulic BBW brake device, the output transition of the hydraulic pressure sensor 6 at the time of the sudden depression operation of the brake pedal 1 is mistaken for the driver's intention of operating the brake pedal, and the brake is applied. Since the control device 10 controls the amount of the brake fluid supplied to the wheel brake 4 from the hydraulic pressure generation control device 7, the deceleration once increases suddenly on the brake feeling, and then the increased deceleration decreases. Which is not preferable.

The present invention has been made in consideration of the above problems, and has as its object to improve the brake feeling of a hydraulic BBW brake device.

[0022]

According to the first aspect of the present invention,
A master cylinder connected to the brake pedal and supplying brake fluid based on operation of the brake pedal, a fluid pressure sensor for detecting a fluid pressure of the brake fluid supplied from the master cylinder, and connected to the master cylinder; A stroke simulator that receives the brake fluid supplied from the master cylinder and applies a reaction force corresponding to the depression stroke of the brake pedal to the brake pedal, and is connected to the master cylinder in parallel with the stroke simulator and supplied. Wheel brakes that generate a braking force based on the hydraulic pressure of the brake fluid, and on-off valves provided in a flow path between the master cylinder and the stroke simulator and in a flow path between the master cylinder and the wheel brake, respectively. Between the master cylinder and the wheel brake In order to generate a predetermined braking force by the wheel brake corresponding to the operation amount of the brake pedal, the wheel brake is connected to the wheel brake based on the output of the hydraulic pressure sensor. A hydraulic pressure generation control device that controls the supply of brake fluid, and controls the open / close valve by depressing a brake pedal to communicate between the master cylinder and a stroke simulator, and that the master cylinder And a wheel brake, wherein the hydraulic pressure generation control device generates a braking force corresponding to the operation amount of a brake pedal by the hydraulic pressure generation control device. A throttle is provided on the way to the pressure sensor.

According to a second aspect of the present invention, a fluid consuming mechanism comprising a variable volume chamber for storing brake fluid is connected to the hydraulic pressure sensor side of the throttle provided on the way to the hydraulic pressure sensor. It is characterized by becoming.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brake device according to an embodiment of the present invention will be described below with reference to FIGS. In addition,
In the description, the same components as those of the hydraulic BBW brake device shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, in a flow path 31 between the master cylinder 2 and the stroke simulator 3, a flow path 31m on the master cylinder 2 side with respect to a normally closed solenoid valve 5s as an on-off valve is provided. A master cylinder hydraulic pressure sensor 6 for detecting the output hydraulic pressure is connected.

In the passage 33m for introducing the brake fluid to the master cylinder fluid pressure sensor 6 with respect to the flow path 31m, the throttle 22 is provided with filters 21 and 21 on both sides.

The filters 21 and 21 are for preventing foreign substances from flowing into the throttle 22 and closing the throttle 22 to prevent the output hydraulic pressure of the master cylinder 2 from being transmitted to the master cylinder hydraulic pressure sensor 6. .

Thus, when the brake pedal 1 is depressed, the normally closed solenoid valve 5s opens based on the output of the brake lamp switch 9 and the normally opened solenoid valve 5w
Is closed, the piston (not shown) in the master cylinder 2 strokes due to the depression operation of the brake pedal 1, and the brake fluid discharged from the master cylinder 2 passes through the stroke simulator 3 and the It will flow into the master cylinder pressure sensor 6.

At this time, if the depressing operation of the brake pedal 1 is a sudden operation, the flow of the brake fluid into the stroke simulator 3 is delayed by the throttle effect of the normally closed solenoid valve 5s itself in the opened state. In this case, the flow of the brake fluid into the master cylinder fluid pressure sensor 6 can also be delayed by the action of the throttle 22 provided in the brake fluid introduction passage 33 of the master cylinder fluid pressure sensor 6.

As a result, the increase in the magnitude of the hydraulic pressure output of the master cylinder 2 detected by the master cylinder hydraulic pressure sensor 6 is synchronized with the increase in the amount of brake fluid sent from the master cylinder 2 into the stroke simulator 3. As a result, it is possible to prevent a decrease in the output of the master cylinder pressure sensor 6 which has been suddenly increased, which has conventionally occurred when the depression operation of the brake pedal 1 is a sudden operation.

Therefore, the master cylinder hydraulic pressure sensor 6
Can be made to correspond to the degree of increase in the hydraulic pressure of the stroke simulator 3 determined by the amount of brake fluid sent into the stroke simulator 3, and the response of the brake pedal 1 provided by the stroke simulator 3 Good brake feeling can be obtained.

A general hydraulic pressure sensor applied to the master cylinder hydraulic pressure sensor 6 is a metal seal or O
It is mounted liquid-tight using a ring. As a result, the general hydraulic pressure sensor consumes a very small amount of liquid. When the general hydraulic pressure sensor is applied as the master cylinder hydraulic pressure sensor 6 in the above-described first embodiment, the throttle 22 must be closed. Must have a very small aperture diameter,
Its production becomes difficult.

Therefore, a second embodiment of the present invention is shown in FIG.
As shown in the figure, a liquid volume absorbing mechanism 24 composed of a chamber having a variable volume for storing brake fluid is provided in the introduction path 33 s closer to the fluid pressure sensor 6 than the throttle 22 provided in the brake fluid pressure introduction path 33. It is composed.

The liquid amount absorbing mechanism 24 includes a housing 25
A space 25S formed therein is defined by a piston 27 urged by a spring 26 into a first chamber 28 and a second chamber 29. The first chamber 28 is
And communicates with the inlet path 33s on the hydraulic pressure sensor 6 side.
The two chambers 28, 29 can be changed in volume so that a sufficient amount of brake fluid can be consumed in the second chamber 29 so that the production of the throttle diameter of 2 is easy.

As a result, in the second embodiment of the present invention, even when a general hydraulic pressure sensor is applied as the master cylinder hydraulic pressure sensor 6, the brake pedal 1 can be used without making the throttle 22 an extremely small diameter. When the depressing operation is a sudden operation, the degree of increase in the hydraulic pressure of the master cylinder hydraulic pressure sensor 6 can easily correspond to the degree of increase in the hydraulic pressure of the stroke simulator 3 which is determined by the amount of brake fluid sent into the stroke simulator 3. it can.

FIG. 3 shows a detailed specific example of the liquid amount absorbing mechanism 24 in the second embodiment.

In FIG. 3, reference numeral 41 denotes a housing.
A mounting hole 42 having a bottom is formed in the housing 41, and the introduction passage 3 is formed at the center of the bottom of the conical taper of the mounting hole 42.
The flow path 43 formed in the housing 41 and constituting the 3s
Is open. In the mounting hole 42, a plug 45 having a piston 44 mounted thereon and a sensor housing 46 of a hydraulic pressure sensor are housed in series from the opening side to the bottom side in the axial direction.

Here, the plug 45 has a large-diameter portion 45a fitted to the peripheral wall surface of the mounting hole 42, and a smaller diameter than the large-diameter portion 45a, between the outer peripheral surface and the peripheral wall surface of the mounting hole 42. And a small-diameter portion 45b forming the space 25S.
A sensor mounting hole 45c for mounting the sensor housing 46 is formed inside the b side.

The large-diameter portion 45a of the plug 45 has a radially outer peripheral portion provided with the above-described flow path 43 and the space 25S.
Is formed, and a liquid passage 45e that forms the introduction passage 33s is formed at the center of the liquid passage 45d.

On the other hand, in the sensor housing 46, a hydraulic pressure introduction port 46a facing the liquid passage 45e of the plug 45 is opened at the front end surface, and the sensor body mounting hole 45c of the plug 45 is formed.
And a tip end 46b which is screw-fitted in a liquid-tight manner via an O-ring 47
And a fluid pressure sensor main body (not shown) is housed inside, and the outer peripheral portion is attached to the mounting hole 42.
And a base end portion 46c that is screwed with the inner peripheral surface of the opening side portion.

On the other hand, the piston 44 comprises an annular piston slidably mounted in the axial direction on the outer peripheral surface of the small diameter portion 45b of the plug 45, and has a space 25S provided on the outer periphery of the base end portion 46c. A first chamber 28 which is always maintained at the atmospheric pressure by the ventilation groove 46d, and a second chamber 29 which stores the brake fluid supplied from the master cylinder 2 through the above-described throttle 22 and the flow path 43. To achieve. In addition, 4
Reference numerals 7 and 48 denote an annular cup seal and a backup ring provided on the piston 44.

The tip 4 of the sensor housing 46
Step 46e is formed between 6b and base end 46c,
A spring 49 is provided between the step portion 46 e and the piston 44 in the first chamber 28 so as to urge the piston 44 toward the plug 45.

Thus, according to this embodiment, the fluid absorption mechanism 24 can be integrated with the fluid pressure sensor 6, so that the size can be reduced.

The third and fourth embodiments of the present invention are different from the first and second embodiments in which the throttle 22 is provided in the passage 33 for introducing the brake fluid to the master cylinder fluid pressure sensor 6 with reference to FIGS.
As shown by broken lines therein, the flow of the brake fluid from the flow channel 31m side to the master cylinder hydraulic pressure sensor 22 side is prevented in parallel with the throttle 22, and the master cylinder hydraulic pressure sensor 6 side to the flow channel 31m side. The outflow of brake fluid is provided by adding an allowable check valve 51.

That is, in the first and second embodiments described above, when the brake pedal 1 which is being depressed is suddenly released, the master cylinder hydraulic pressure sensor 6
Out of the brake fluid from the side to the flow path 31m
2, the output fluid pressure of the master cylinder 2 detected by the master cylinder fluid pressure sensor 6 also decreases due to the sudden release of the brake pedal 1 from the brake pedal 1 release operation. You will be delayed by minutes.

On the other hand, in the case of the third and fourth embodiments, the master cylinder 2 which is detected by the master cylinder hydraulic pressure sensor 6 for the operation of releasing the brake pedal 1 suddenly is released.
Can be eliminated by the check valve 51, and even if the brake pedal 1 is suddenly depressed and released, the favorable brake feeling is not impaired.

In the third and fourth embodiments, the check valve 51 is provided so as to bypass the filters 21 and 21 in addition to the throttle 22. However, the check valve 51 may be provided so as to bypass only the check valve 51.

[0048]

As described above, according to the present invention,
Even when the brake pedal is depressed suddenly, the pressure transmission to the hydraulic pressure sensor, which detects the output hydraulic pressure of the master cylinder, depends on the amount of brake fluid sent to the stroke simulator. Since it can be delayed correspondingly, the brake feeling of the hydraulic BBW brake device can be improved.

[Brief description of the drawings]

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

FIG. 2 is a view showing a brake device according to another embodiment of the present invention.

FIG. 3 is a diagram showing a specific example of a configuration of a liquid amount absorbing mechanism in the brake device of FIG. 2;

FIG. 4 is a view showing a conventional brake device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake pedal 2 Master cylinder 3 Stroke accumulator 4 Wheel brake 5 On-off valve 6 Master cylinder fluid pressure sensor 7 Fluid pressure generation control device 10 Brake control device 21 Filter 22 Throttle 24 Liquid volume absorption mechanism

Claims (2)

[Claims] A master cylinder connected to a brake pedal for supplying brake fluid based on an operation of the brake pedal; a fluid pressure sensor for detecting a fluid pressure of the brake fluid supplied from the master cylinder; A stroke simulator that receives the brake fluid supplied from the master cylinder and applies a reaction force corresponding to the depression stroke of the brake pedal to the brake pedal, and is connected to the master cylinder in parallel with the stroke simulator. And a wheel brake that generates a braking force based on the hydraulic pressure of the supplied brake fluid, a flow path between the master cylinder and the stroke simulator, and a flow path between the master cylinder and the wheel brake, respectively. The on-off valve provided, the master cylinder and the wheel In order to generate a predetermined braking force by the wheel brake in accordance with the operation amount of the brake pedal, the hydraulic pressure sensor is connected to the output of the hydraulic pressure sensor. And a hydraulic pressure generation control device that controls the supply of brake fluid to the wheel brakes based on the brake pedal, and controls the on-off valve by depressing a brake pedal to communicate between the master cylinder and the stroke simulator. A brake device that cuts off between the master cylinder and the wheel brake and generates a braking force corresponding to an operation amount of a brake pedal to the wheel brake by the hydraulic pressure generation control device. A throttle is provided in the middle of a passage for introducing the brake fluid to the hydraulic pressure sensor. Key equipment. 2. A liquid consumption mechanism comprising a variable volume chamber for storing brake fluid is connected to a side of the fluid pressure sensor rather than a throttle provided in the middle of an introduction path to the fluid pressure sensor. The brake device according to claim 1, wherein