JP4446221B2 - Hydraulic brake device for vehicles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic brake device for a vehicle that uses hydraulic pressure to assist a brake pedal depression force, and more particularly to an apparatus that can adjust a hysteresis width in a brake pedal depression force-braking hydraulic pressure characteristic.
[0002]
[Prior art]
Conventionally, for example, as described in JP-A-9-24819, a power piston that is disposed in a cylinder via a seal member and that operates in response to a brake pedal operation to generate a brake fluid pressure, Hydraulic pressure generating means for generating a high pressure, a reservoir for storing hydraulic fluid, a control valve capable of selectively communicating the hydraulic pressure generating means or reservoir to the power chamber, and a position facing the power piston with respect to the control valve A reaction force chamber disposed between the reaction force chamber and the control valve, and a reaction member that is provided between the reaction force chamber and the control valve to apply a reaction force due to hydraulic pressure in the reaction force chamber to the control valve. When the hydraulic pressure in the power chamber is adjusted to substantially the same pressure as the braking hydraulic pressure by receiving the reaction force from the reaction member, and the hydraulic pressure in the power chamber is guided to the reaction force chamber. Hydraulic brake device is known which utilizes a hydraulic pressure of the power chamber to assist the depression force of the brake pedal operation.
[0003]
In this case, when the brake pedal is depressed, the power piston is activated and brake fluid pressure is generated. On the other hand, the control valve controls the fluid pressure in the power chamber to be approximately the same as the brake fluid pressure, and this power is applied. The hydraulic pressure in the room is guided to the reaction force chamber, and the brake pedal depression force can be subsidized with a predetermined servo ratio by using the hydraulic pressure in the power chamber.
[0004]
[Problems to be solved by the invention]
By the way, in the above-described hydraulic brake device for a vehicle, the power piston that operates according to the operation of the brake pedal is disposed so as to be slidable in the cylinder via the seal member. Indispensable for partitioning each chamber in the apparatus. Therefore, when the power piston slides in the cylinder, a sliding frictional resistance is inevitably generated due to the frictional force generated on the seal surface of the seal member. And at the time of decompression, it has a predetermined hysteresis width. As the hysteresis width increases, the change in braking fluid pressure with respect to the brake pedal depression force increase / decrease operation becomes slow. There is an optimum width that makes it easier to control the pressure. Therefore, in the above-described hydraulic brake device for a vehicle, the hysteresis width cannot be adjusted. Therefore, it has not always been felt that the driver can control the brake hydraulic pressure most easily.
[0005]
The present invention has been made to solve the above problem, and in a hydraulic brake device for a vehicle that uses hydraulic pressure to assist a brake pedal depression force, a hysteresis width in a brake pedal depression force-braking hydraulic pressure characteristic can be adjusted. It is an object to provide things.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a power piston that is disposed in a cylinder via a seal member and that operates in response to a brake pedal operation to generate a brake hydraulic pressure, and a hydraulic pressure that generates a predetermined high pressure. Generating means, a reservoir for storing hydraulic fluid, a control valve capable of selectively communicating the hydraulic pressure generating means or reservoir to the power chamber, and a reaction force chamber disposed at a position facing the power piston with respect to the control valve And a reaction member that is interposed between the reaction force chamber and the control valve and applies a reaction force due to the hydraulic pressure in the reaction force chamber to the control valve, and the control valve operates according to the operation of the power piston. At the same time, by receiving the reaction force from the reaction member, the hydraulic pressure in the power chamber is adjusted to be approximately the same as the braking hydraulic pressure, and the pedal pressure for operating the brake pedal is subsidized using the hydraulic pressure in the power chamber. In the dual-use hydraulic brake device, a power chamber pressure sensor that detects a fluid pressure in the power chamber, a reaction force chamber pressure sensor that detects a fluid pressure in the reaction force chamber, a pedaling force sensor that detects a pedaling force of the brake pedal operation, A reaction force chamber pressure adjusting means capable of adjusting the hydraulic pressure in the reaction force chamber using the high pressure generated by the pressure generating means, and the reaction force chamber pressure adjusting means is configured to reduce the braking hydraulic pressure based on the output result of the pedal force sensor. When it is determined that the pressure is increased or maintained, the hydraulic pressure in the reaction chamber is controlled to be the same as the hydraulic pressure in the power chamber, and it is determined that this is the initial stage in which the braking hydraulic pressure is reduced based on the output result of the pedal force sensor. In some cases, the hydraulic brake device for a vehicle is characterized in that the hydraulic pressure in the reaction chamber is controlled to be higher than the hydraulic pressure in the power chamber by a predetermined pressure. Here, “the step of increasing the brake fluid pressure” means a step where the brake pedal depression force is increasing, that is, a step where the brake pedal and the power piston are moving forward, and “a step of maintaining the brake fluid pressure”. Means the stage where the brake pedal depression force is substantially constant, that is, the stage where the positions of the brake pedal and the power piston are substantially constant. The "initial stage of reducing the brake fluid pressure" means that the brake pedal depression force is It refers to the initial stage in which the brake pedal and the power piston begin to return, i.e., the stage where the brake pedal and power piston begin to return.
[0007]
Thus, according to the present invention, the hydraulic pressure in the reaction force chamber can be adjusted using the reaction force chamber pressure adjusting means, and the reaction force chamber pressure adjusting means increases or decreases the braking hydraulic pressure according to the output result of the pedal force sensor. When it is determined that it is a holding stage, the hydraulic pressure in the reaction chamber is controlled to be the same as the hydraulic pressure in the power chamber, and when it is determined that it is the initial stage in which the braking hydraulic pressure is reduced based on the output result of the pedal force sensor The hydraulic pressure in the reaction chamber is controlled to be higher than the hydraulic pressure in the power chamber by a predetermined pressure. That is, in the step of increasing or maintaining the braking hydraulic pressure, the hydraulic pressure in the reaction chamber is the same as the hydraulic pressure in the power chamber, which is the same as that of the conventional device described above, but the initial stage of reducing the braking hydraulic pressure. Is controlled so that the hydraulic pressure in the reaction force chamber is higher than the hydraulic pressure in the power chamber by a predetermined pressure.
[0008]
Therefore, at the initial stage of reducing the brake fluid pressure, the control valve presses the power piston in the return direction due to the increase in the reaction force received by the control valve from the reaction member due to the fluid pressure in the reaction force chamber increased by a predetermined pressure. A return force is generated. Such a return force acts in a direction to cancel the sliding frictional force generated by the seal member when the power piston starts to return. Therefore, the hysteresis width in the brake pedal depression force-braking hydraulic pressure characteristic can be adjusted by adjusting the "predetermined pressure" and adjusting the return force.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of an axial cross section of a hydraulic brake device for a vehicle according to an embodiment of the present invention. First, the mechanical configuration will be described with reference to FIG.
[0010]
In FIG. 1, a stepped power piston 2 is slidably disposed in a cylinder 1. An O-ring 25 (seal member) and a cup seal 26 (seal member) are disposed on the outer peripheral surfaces of the large diameter portion 2b and the medium diameter portion 2c of the power piston 2, respectively. A cup seal 23 (seal member) and an O-ring 24 (seal member) are disposed on the inner peripheral surface of the cylinder 1 facing each other. The power piston 2 is connected to a brake pedal (not shown), and the pedaling force from the brake pedal (not shown) is indicated by F in the figure.
[0011]
A piston 3 is slidably disposed in series with the power piston 2 in the cylinder 1, and an O-ring 27 is disposed on the outer peripheral surface of the piston 3. The space between the power piston 2 and the piston 3 is liquid-tightly divided by a cup seal 26 and an O-ring 27 to form a pressure chamber 19 in which a braking hydraulic pressure Pm is generated. It is connected via a port 20 to a front wheel cylinder (not shown). Between the power piston 2 and the piston 3, a spring 7 that generates a predetermined urging force in a direction to separate them is disposed. Further, a spring 8 that generates a biasing force that constantly biases the piston 3 to the right in FIG. 1 is provided.
[0012]
The control valve 4 is slidably disposed so as to be able to contact the left end surface of the piston 3 in FIG. 1 and the right end surface of the member 5 disposed in the cylinder 1. The land portion 4 a of the control valve 4 connects and disconnects the port 17 communicating with the hydraulic pressure generating means 11 and the power chamber 21 according to the axial position of the control valve 4, and the land portion 4 b of the control valve 4 is connected to the oil passage 15. The land 4 b of the control valve 4 is connected to the power chamber 21, and the port 16 communicating with the reservoir 9 and the power chamber 21 are intermittently connected according to the axial position of the control valve 4. Therefore, when the control valve 4 moves to the left in FIG. 1, the hydraulic pressure generating means 11 and the power chamber 21 communicate with each other, the hydraulic pressure Pp in the power chamber 21 increases, and the control valve 4 moves to the right in FIG. Is moved, the reservoir 9 and the power chamber 21 communicate with each other, and the hydraulic pressure Pp in the power chamber 21 decreases. Accordingly, the hydraulic pressure Pp in the power chamber 21 is controlled by the movement of the control valve 4.
[0013]
The reaction member 6 made of an elastic member is disposed on the left side of the member 5 in FIG. 1, and a reaction force chamber 18 is formed on the left side of the reaction member 6 in FIG. The reaction member 6 receives the hydraulic pressure P in the reaction force chamber 18 and elastically deforms so that the reaction force due to the hydraulic pressure P can be applied to the control valve 4 via the member 5. .
[0014]
The hydraulic pressure generating means 11 generates a predetermined high pressure. For example, a pump that pumps hydraulic fluid from the reservoir 9, a motor that controls the pump, and a hydraulic pressure discharged from the pump is maintained at a predetermined high pressure. It can comprise from the accumulator etc. which can store. The predetermined high pressure generated by the hydraulic pressure generating means 11 is supplied to a reaction force chamber pressure adjusting means and a port 17 described below.
[0015]
The reaction chamber pressure adjusting means includes a normally closed linear solenoid valve 12, a normally closed linear solenoid valve 13, and a controller (not shown) that controls these solenoid valves. The normally closed linear electromagnetic valve 12 is interposed between the hydraulic pressure generating means 11 and the reaction force chamber 18, and the normally closed linear electromagnetic valve 13 is interposed between the reaction force chamber 18 and the reservoir 10. ing. Accordingly, the hydraulic pressure P in the reaction force chamber 18 increases when the linear electromagnetic valve 12 is opened, and decreases when the linear electromagnetic valve 13 is opened. Therefore, the hydraulic pressure P in the reaction force chamber 18 is controlled by controlling the opening and closing of these two linear electromagnetic valves. The hydraulic pressure P in the reaction force chamber 18 is constantly monitored by the reaction force chamber pressure sensor 30.
[0016]
The power chamber 21 is connected to the space 22 and a rear wheel cylinder (not shown) via the oil passage 14. The power chamber pressure Pp guided to the space 22 acts on the right side surface in FIG. 1 of the large diameter portion 2b of the power piston 2, so that the brake pedal depression force F is subsidized by the power chamber pressure Pp. Yes. The power chamber pressure Pp is constantly monitored by the power chamber pressure sensor 28. Further, the brake pedal depression force F can be detected by a depression force sensor 29 disposed on the right end surface of the small diameter portion 2a of the power piston 2 in FIG.
[0017]
The mechanical configuration of the vehicle hydraulic brake device according to the embodiment of the present invention has been briefly described above with reference to FIG. Next, the operation will be described with reference to FIGS. FIG. 2 is a graph showing a brake pedal depression force-braking fluid pressure Pm characteristic.
[0018]
In FIG. 1, when a brake pedal (not shown) is depressed, the power piston 2 moves to the left in FIG. 1 to generate the brake fluid pressure Pm in the sealed pressure chamber 19 and also the piston 3. Moves to the left in conjunction with the power piston 2. As the piston 3 moves to the left, the control valve 4 is also pressed by the piston 3 and moves to the left. When the control valve 4 moves to the left by a predetermined amount, the land portion 4a of the control valve 4 communicates with the port 17, the hydraulic pressure generating means 11 generating a predetermined high pressure, and the power chamber 21 communicate with each other. The hydraulic pressure Pp in the chamber 21 increases. The power chamber pressure Pp is also supplied to the space 22, whereby the power piston 2 receives a leftward assisting force in FIG. 1 and a pedaling force of a brake pedal (not shown) is further assisted. Here, when the power piston 2 and the piston 3 start to move leftward in FIG. 1, the cup seal 23, the O-ring 24, the O-ring 25, the cup seal 26, and the O-ring 27, which are seal members, are used. A sliding frictional force is generated in the right direction in FIG.
[0019]
On the other hand, when a brake pedal (not shown) is depressed, the pedal force detected by the pedal force sensor increases. Therefore, the controller (not shown) determines this stage as a "stage for increasing the brake fluid pressure" and the controller (not shown) The normally closed linear electromagnetic valves 12 and 13 are controlled to open and close so that the reaction force chamber pressure P detected by the force chamber pressure sensor 30 is the same as the power chamber pressure Pp detected by the power chamber pressure sensor. As described above, the reaction chamber pressure P is controlled to be the same as the power chamber pressure Pp in the “step of increasing the brake fluid pressure”, so that the reaction member 6 is pressed rightward in FIG. The reaction force is transmitted to the control valve 4 via the member 5, and the control valve 4 is pressed rightward in FIG. 1 by the reaction force, so that the land portion 4 b of the control valve 4 is connected to the port 16. The reservoir 9 and the power chamber 21 communicate with each other, and the hydraulic pressure Pp in the power chamber 21 decreases. As a result, the control valve 4 is balanced by the depressing force of a brake pedal (not shown) and the reaction force from the reaction member 6 due to the reaction force chamber pressure P, and the power chamber pressure Pp is adjusted in the pressure chamber 19 corresponding to the depressing force of the brake pedal. The brake fluid pressure Pm is servo-controlled at a predetermined servo ratio with respect to the brake pedal depression force. If this stage is shown in the brake pedal depression force-braking hydraulic pressure characteristic diagram, it becomes like the "pressure increase" stage in FIG.
[0020]
In FIG. 2, when the brake pedal depression force is substantially constant after reaching point a, the controller (not shown) determines that “the stage of maintaining the brake fluid pressure” and the controller (not shown) The chamber pressure P is maintained at the same pressure as the power chamber pressure Pp.
[0021]
Thereafter, when the brake pedal depression force starts to decrease, the controller (not shown) determines that it is “an initial stage for reducing the brake fluid pressure” and is normally closed so that the reaction chamber pressure P is higher than the power chamber pressure Pp by a predetermined pressure. The linear solenoid valves 12 and 13 are controlled. Therefore, in the initial stage of reducing the brake fluid pressure, the control valve 4 is driven by the increase in the reaction force received by the reaction valve 6 from the reaction member 6 due to the reaction force chamber pressure P increased by “predetermined pressure”. A return force that presses the piston 2 in the return direction (rightward in FIG. 1, refer to “f”) is generated. Such “returning force” acts in a direction to cancel the sliding frictional force leftward in FIG. 1 generated by the seal members 23 to 27 when the power piston 2 and the piston 3 start to return.
[0022]
This state will be described with reference to FIG. 2. Even when the brake hydraulic pressure is reduced, the reaction chamber pressure P is maintained at the same pressure as the power chamber pressure Pp as in the conventional vehicle hydraulic brake device. The power pistons 2 and 3 that are about to start returning without the “returning force” acting until they reach the point b that overcomes the resultant force of the sliding frictional force to the left in FIG. Does not start sliding, and the hysteresis width is L in FIG. However, as in the present invention, by applying the “returning force”, the sliding frictional force by the seal members 23 to 27 is offset by that amount, and the power pistons 2 and 3 that are about to start returning start sliding. Since the force that must be overcome decreases, as a result, when the point b ′ is reached, the power pistons 2 and 3 start to slide, and the process proceeds to the step of reducing the brake hydraulic pressure Pm (FIG. 2). In dotted line). In this case, the hysteresis width is L ′, and the hysteresis width in the brake pedal depression force-braking hydraulic pressure Pm characteristic diagram is reduced (from L to L ′) as compared with the conventional device. Here, the “return force” in FIG. 1 is a value obtained by multiplying the “predetermined pressure”, which is an increase in the reaction force chamber pressure P, by the reaction member reaction force pressure receiving area S5 of the member 5. Needless to say, the “returning force” is set within a range not exceeding the resultant force of the sliding frictional force by the seal members 23 to 27.
[0023]
As described above, according to the present invention, by adjusting the “predetermined pressure” and adjusting the “returning force”, it is possible to adjust the hysteresis width in the brake pedal depression force-braking fluid pressure characteristic, and the driver can It is possible to provide a hydraulic brake device for a vehicle that can be adjusted to a hysteresis width that makes it easy to control the pressure.
[0024]
【The invention's effect】
As described above, according to the present invention, in a hydraulic brake device for a vehicle that uses hydraulic pressure to assist a brake pedal depression force, it is possible to provide a device capable of adjusting a hysteresis width in a brake pedal depression force-braking hydraulic pressure characteristic. As a result, it is possible to provide a hydraulic brake device for a vehicle that can be adjusted to a hysteresis width that is felt that the driver can most easily control the brake hydraulic pressure.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an axial cross section of a hydraulic brake device for a vehicle according to an embodiment of the present invention.
FIG. 2 is a graph showing a brake pedal depression force-braking fluid pressure Pm characteristic.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylinder 2 Power piston 4 Control valve 6 Reaction member 9 Reservoir 10 Reservoir 11 Fluid pressure generation means 12, 13 Normally closed linear solenoid valve (reaction force chamber pressure adjustment means)
18 Reaction room 21 Power room 22 Space (Power room)
23, 26 Cup seal (seal member)
24, 25, 27 O-ring (seal member)
28 Power chamber pressure sensor 29 Treading force sensor 30 Reaction force chamber pressure sensor

Claims (1)

A power piston that is disposed in the cylinder via a seal member and that operates in response to a brake pedal operation to generate a brake fluid pressure; a fluid pressure generating means that generates a predetermined high pressure; and a reservoir that stores hydraulic fluid; A control valve capable of selectively communicating the hydraulic pressure generating means or the reservoir with a power chamber, a reaction force chamber disposed at a position facing the power piston with respect to the control valve, and the reaction force chamber; A reaction member that is interposed between the control valve and applies a reaction force due to the hydraulic pressure in the reaction force chamber to the control valve, and the control valve operates in accordance with the operation of the power piston. By receiving the reaction force from the reaction member, the hydraulic pressure in the power chamber is adjusted to be substantially the same as the braking hydraulic pressure, and the brake is adjusted using the hydraulic pressure in the power chamber. In the vehicle hydraulic brake device for assisting the pedaling force of the dull operation, a power chamber pressure sensor for detecting the hydraulic pressure in the power chamber, a reaction chamber pressure sensor for detecting the hydraulic pressure in the reaction chamber, and the brake pedal A reaction force chamber pressure adjusting means capable of adjusting a fluid pressure in the reaction force chamber using a high pressure generated by the fluid pressure generation means; The adjusting means controls the hydraulic pressure in the reaction force chamber to be the same as the hydraulic pressure in the power chamber when it is determined that it is a step of increasing or holding the braking hydraulic pressure from the output result of the pedal force sensor. Controlling the hydraulic pressure in the reaction chamber to be higher by a predetermined pressure than the hydraulic pressure in the power chamber when it is determined from the output result of the pedal force sensor that it is an initial stage of reducing the braking hydraulic pressure. Hydraulic brake equipment for vehicles .

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