JP6547454B2 - Stroke simulator - Google Patents

Description

The present invention relates to a stroke simulator that generates a stroke of a size corresponding to the operating force of a brake pedal on a brake pedal.

The conventional stroke simulator is configured to move the first piston, the second piston, and the rubber cap, which move in the housing based on the hydraulic pressure according to the operating force of the driver's brake pedal, and the maximum movement of the rubber cap when the hydraulic pressure rises. A rubber receiver which limits the range, and a first spring and a second spring which bias the first piston, the second piston and the rubber cap in the direction opposite to the fluid pressure. Further, in the inner peripheral portion of the housing, a first simulator chamber defined by the housing and the first piston and a second simulator chamber opposite to the first simulator chamber are formed. Also, the first spring is disposed between the first piston and the second piston, and the second spring is disposed between the second piston and the rubber receiving portion. Furthermore, the first piston has a substantially cylindrical shape, and a ring-shaped cup is attached to an annular groove formed on the surface of the cylinder, and the cup axially slidably presses the inner peripheral portion of the housing Seal the first simulator room.

JP 2007-210372

In the conventional stroke simulator described in Patent Document 1 described above, the first piston moves toward the rubber cap while compressing the first spring as the hydraulic pressure increases according to the operation force of the driver's brake pedal. Then, while compressing the second spring, the second piston and the rubber cap move integrally toward the rubber receiving portion, and the repulsive force of the spring at this time gives the driver a predetermined brake feeling. There is.

In addition, a rubber shock absorbing elastic body is attached to the rubber cap, and the shock absorbing elastic body is compressed near the end of the compression of the first spring and the end of the compression of the second spring. The following curve is smoothly changed to give the driver a good brake feeling.

However, in the stroke simulator described in Patent Document 1 mentioned above, since the operation force of the brake pedal at the initial stage of the brake operation by the driver is small, the cup attached to the first piston presses the housing slidably in the axial direction. The impact of sliding resistance is large. As a result, the brake feeling felt by the driver differs between the initial state of the brake operation where the driver's operating force of the brake pedal is small and the state where the driver's operating force of the brake pedal is sufficient. As a result, there is a possibility that the driver may feel discomfort in the brake operation.

Then, this invention aims at providing the stroke simulator which can improve a brake feeling by simple structure.

In order to solve the above-mentioned problems, the invention according to claim 1 is a stroke simulator device for causing a brake pedal to generate a stroke having a size corresponding to the operation force of the brake pedal, and a housing and a housing A fluid-tightly disposed first piston and a fluid pressure chamber formed on one end side of the first piston and supplied with a fluid pressure corresponding to the operating force of the brake pedal, and a fluid pressure chamber of the first piston An annular groove is formed on the outer peripheral surface of the second piston disposed at the other end and movable integrally with the first piston, and the first piston is press-fit into the annular groove and the housing An elastic member slidably pressed to the inner circumferential surface, a stopper for restricting the movement range of the second piston in the direction in which the volume of the fluid pressure chamber increases, and a stopper disposed between the first piston and the second piston Decrease the volume of the hydraulic pressure chamber And a second spring for urging the second piston in the direction in which the volume of the fluid pressure chamber decreases, and the brake pedal is not operated, and the first piston is provided. In the initial position, the inner circumferential surface of the housing has a first pressing surface on which the elastic member presses the inner circumferential surface of the housing, and the brake pedal is operated to move the first piston a predetermined distance The inner circumferential surface of the housing has a second pressing surface on which the elastic member presses the inner circumferential surface of the housing, and the first inner diameter, which is the inner diameter of the housing at the first pressing surface, corresponds to that of the housing at the second pressing surface It is characterized in that it is set larger than the second inner diameter which is the inner diameter.

According to the first aspect of the present invention, the first inner diameter, which is the inner diameter of the housing when the brake pedal is not operated and the piston is in the initial position, is the inner diameter of the housing when the brake pedal is operated and the piston has moved a predetermined distance. It is set larger than a certain second inner diameter. Thereby, when the driver operates the brake, the pressing force between the elastic member and the inner peripheral surface of the housing at the initial stage of the operation of the brake pedal is increased as the brake pedal is operated and the piston moves a predetermined distance. Can. Therefore, in the initial stage of the operation of the brake pedal, the sliding resistance between the cup seal and the inner peripheral surface of the housing can be reduced, and the resistance to the driver's braking operation can be reduced, so that the brake feeling can be improved. Furthermore, when the operating force of the driver is sufficiently increased with the operation of the brake pedal, the influence of the sliding resistance between the elastic member and the inner peripheral surface of the housing is small, so that the elastic member and the inner peripheral surface of the housing There is no problem in increasing the pressing force, and the sealing performance by the elastic member can be reliably ensured by the present invention.

Further, the hydraulic pressure chamber side of the housing is characterized by being formed with a third inner diameter smaller than the first inner diameter at a position of a predetermined distance from the elastic member.

According to the second aspect of the present invention, the initial position of the first piston in the non-operation state of the brake pedal (same as when the operation of the brake pedal is released) is the position where the first inner diameter and the third inner diameter switch. It is determined. That is, since the sliding resistance between the elastic member at the third inner diameter and the inner peripheral surface of the housing is larger than the sliding resistance between the elastic member at the first inner diameter and the inner peripheral surface of the housing, the first piston Axial movement to the chamber side can be restricted. Therefore, the initial position of the first piston in the non-operation state of the brake pedal can be made constant, so that the brake feeling can be made uniform at the initial stage of the operation of the brake pedal, and the brake feeling can be improved. Can.

The block diagram of the brake device using the stroke simulator of 1st Embodiment in this invention Cross section of the stroke simulator in FIG. 1 An enlarged sectional view of the cup seal portion in FIG. 1 An enlarged sectional view of the cup seal portion at the time of operation of the stroke simulator of FIG. 1 Cross-sectional view of a stroke simulator according to a second embodiment of the present invention

Hereinafter, the first embodiment of the present invention will be specifically described with reference to FIGS. 1 to 3, but the present invention is not limited to the following embodiment as long as the purpose of the present invention is not exceeded.

FIG. 1 shows a brake device using a stroke simulator 40 according to a first embodiment of the present invention. In the same figure, the hydraulic circuit of the brake device is shown for four wheels (FL, FR, RL, RR), but the configuration and operation of the parts related to the brake fluid pressure control of each wheel are common. Here, only the left front wheel (FL) will be described, and the description of the configuration and operation of the other wheels will be omitted.

The brake pedal 10 is depressed by the driver when applying a braking force to the vehicle. The stroke sensor 20 detects a stroke of the brake pedal 10 (hereinafter referred to as a pedal stroke), and generates an electric signal according to the pedal stroke.

The master cylinder 30 generates a brake fluid pressure by depression of the brake pedal 10, and the brake fluid pressure is transmitted to a stroke simulator 40 described later via a conduit A, and at the same time, for the left front wheel via a conduit B. It is transmitted to the wheel cylinder 50.

In the conduit A, a first cut valve 80 for opening and closing the conduit A is disposed. The first cut valve 80 is a normally closed solenoid valve.

In the conduit B, a second cut valve 61 of a normally open solenoid valve for opening and closing the conduit B is disposed. Hereinafter, in the conduit B, a portion between the second cut valve 61 and the master cylinder 30 is referred to as an M / C side conduit B1, and a portion between the second cut valve 61 and the wheel cylinder 50 is referred to as a W / C side conduit B2. It is said.

A first pressure sensor 62 for detecting the brake fluid pressure in the M / C side conduit B1 is disposed in the M / C side conduit B1, and the first pressure sensor 62 is an electrical signal corresponding to the brake fluid pressure. Generate. Further, a second pressure sensor 63 for detecting the brake fluid pressure in the W / C side conduit B2 is disposed in the W / C side conduit B2, and the second pressure sensor 63 is adapted to the brake fluid pressure. Generate an electrical signal.

A conduit C is connected to the W / C side conduit B2. A pump 71, an accumulator 72, a relief valve 73, and a third pressure sensor 74 for detecting the brake fluid pressure of the conduit C are disposed in the conduit C as a fluid pressure source 70 for generating the brake fluid pressure. The third pressure sensor 74 generates an electrical signal corresponding to the brake fluid pressure. The hydraulic pressure source 70 sucks in and discharges the brake fluid from the reservoir of the master cylinder 30 by a pump 71 driven by an electric motor, stores the discharged high-pressure brake fluid in the accumulator 72, and applies the pressure of the brake fluid. The pressure is detected by the third pressure sensor 74 and adjusted to the set pressure.

In the pressure intensifying line C1 from the third pressure sensor 74 to the portion connected to the W / C side line B2 in the line C, a pressure increasing valve 81 for opening and closing the pressure intensifying line C1 is disposed. When the pressure intensifying valve 81 is opened, high pressure brake fluid is supplied from the hydraulic pressure source 70 to the wheel cylinder 50, and the brake fluid pressure in the wheel cylinder 50 is increased. The pressure increasing valve 81 is a normally closed solenoid valve.

In the conduit C, a pressure reducing valve 82 for opening and closing the pressure reducing conduit C2 is disposed in the pressure reducing conduit C2 from the part connected to the W / C side conduit B2 to the suction side of the hydraulic pressure source 70 There is. When the pressure reducing valve 82 is opened, the brake fluid in the wheel cylinder 50 is returned to the suction side of the hydraulic pressure source 70 or to the reservoir of the master cylinder 30, and the brake fluid pressure in the wheel cylinder 50 is reduced. The pressure reducing valve 82 is a normally closed solenoid valve.

Next, a stroke simulator 40 according to a first embodiment will be described based on FIGS. 2 and 3. FIG. 2 shows a state in which the brake pedal 10 is not operated, and shows a state in which the pressure in the fluid pressure chamber 43 is 0 (that is, the atmospheric pressure).

The stroke simulator 40 is for generating a pedal stroke having a size corresponding to the operating force of the brake pedal 10. And two cylindrical holes 411 and 412 are formed in the housing 41 of the stroke simulator 40. The holes 411 and 412 are coaxially arranged in series.

In the first hole 411, a substantially cylindrical first piston 42 formed of an inelastic member such as S45C is slidably disposed. The inelastic member referred to in the present specification has a significantly smaller amount of elastic deformation compared to rubber, and can be regarded as a rigid body in practice, and corresponds to metal and hard resin.

An annular groove 425 is formed on the outer peripheral surface of the first piston 42, and a cup seal 421 for sealing between the inner peripheral surface of the first hole 411 and the outer peripheral surface of the first piston 42 is formed on the annular groove 425. It is arranged. The cup seal 421 is formed of an elastic member, and is made of, for example, ethylene-propylene-diene copolymer rubber (EPDM). The cup seal 421 corresponds to the elastic member of the present invention.

As shown in FIG. 3, when the brake pedal 10 is not operated and the first piston 42 is in the initial position, the cup seal 421 has a first pressing surface 70 for pressing the inner peripheral surface of the housing 41.

As shown in FIG. 4, the brake pedal 10 is operated, and the first piston 42 is moved by a predetermined distance A in the X direction (volume increase direction X). At this time, the cup seal 421 has a second pressing surface 71 for pressing the inner peripheral surface of the housing 41 formed by the second inner diameter C (see FIG. 1). Here, the predetermined distance A is set as an axial distance necessary for forming the second pressing surface 71, and the predetermined distance A in the present embodiment is the first pressing surface 70 and the second pressing surface 71. Shows the distance between the X-side ends of the

Further, a first inner diameter B which is an inner diameter of the housing in the first pressing surface 70 is set larger than a second inner diameter C which is an inner diameter of the housing 41 in the second pressing surface 71.

Furthermore, on the X direction side of the first pressing surface 70, a tapered portion 80 extending toward the axial center of the housing 41 and connecting the first pressing surface 70 and the second pressing surface 71 smoothly is formed.

A fluid pressure chamber 43 is formed between the bottom of the first hole 411 and one end face of the first piston 42, and the brake fluid pressure is transmitted to the fluid pressure chamber 43 from the master cylinder 30 via the conduit A. It has become so.

In the second hole 412, a flanged cylindrical second piston 44 is disposed to face the other end surface of the first piston 42. In the second piston 44, when the first piston 42 moves in the direction X direction side in which the volume of the fluid pressure chamber 43 increases as the brake fluid pressure rises, the first piston 42 and the second piston 44 From the time of contact, it moves integrally with the first piston 42.

A substantially cylindrical stopper 45 formed of an inelastic member such as aluminum is disposed at the opening of the second hole 412 so as to face the other end surface of the second piston 44. The stopper 45 restricts the moving range of the second piston 44 in the X direction. An O-ring 451 made of, for example, ethylene-propylene-diene copolymer rubber (EPDM) is disposed on the outer peripheral portion of the stopper 45, and a circlip 452 for preventing the stopper 45 from coming off is disposed at the end of the stopper 45. It is set up. The second hole 412 is opened to the atmosphere by a through hole 413, and a waterproof pipe 414 for preventing water from entering the second hole 412 is attached to the through hole 413.

Between the first piston 42 and the second piston 44, a first spring 46 is disposed which biases the first piston 42 in the direction Y (volume reduction direction Y) in which the volume of the fluid pressure chamber 43 decreases. There is. The first spring 46 is a cylindrical compression coil spring made of, for example, spring steel.

A second spring 47 is disposed between the second piston 44 and the stopper 45 to bias the second piston 44 in the Y direction. The second spring 47 is a cylindrical compression coil spring made of, for example, spring steel. The second spring 47 has a spring constant different from that of the first spring 46, and the spring constant of the second spring 47 is set larger (for example, about 10 times) than the spring constant of the first spring 46.

A spring receiving surface 422 supporting one end of the first spring 46 and one end of the first spring 46 are fitted on the surface of the first piston 42 facing the second piston 44, and the radial direction of the first spring 46 is fixed. A cylindrical first fitting portion 423 for restricting the movement range is formed. The outer diameter dimension of the first fitting portion 423 is set larger than the inner diameter dimension in the free state of the first spring 46. Therefore, the first spring 46 is press-fit and assembled to the first fitting portion 423. There is.

The second piston 44 has a disc-like collar portion 441 at an axially intermediate portion thereof, and one spring receiving surface 442 of the collar portion 441 supports the other end of the first spring 46. The other spring receiving surface 443 supports one end of the second spring 47.

The second piston 44 protrudes from the flange portion 441 toward the first piston 42 side, and from the columnar first projection 444 and flange portion 441 that can contact the tip end surface of the fitting portion 423 of the first piston 42 It has a cylindrical second projection 445 that protrudes toward the stopper 45 and can be in contact with the movement range restricting surface 454 of the stopper 45.

The end surface of the fitting portion 423 of the first piston 42 and the end surface of the first projection 444 of the second piston 44 when the brake pedal 10 is not operated and the fluid pressure in the fluid pressure chamber 43 is 0 The movement direction distance between and is the first stroke. The distance in the movement direction between the end surface of the second projection 445 of the second piston 44 and the movement range restricting surface 454 of the stopper 45 in the state of the hydraulic pressure 0 is a second stroke.

The first projection 444 of the second piston 44 engages the other end of the first spring 46 to restrict the radial movement range of the first spring 46. The outer diameter dimension of the first protrusion 444 is set smaller than the inner diameter dimension in the free state of the first spring 46, and therefore, the first spring 46 is assembled to the first protrusion 444 in a non-press-fit state .

A spring receiving surface 453 for supporting the other end of the second spring 47 on the surface of the stopper 45 facing the second piston 44, and a movement range restricting surface on which the tip of the second projection 445 of the second piston 44 can abut. A cylindrical guide portion 455 protruding from the spring receiving surface 453 and the movement range control surface 454 toward the second piston 44 is formed. The second projection 445 of the second piston 44 is slidably inserted in the inner peripheral portion of the guide portion 455, whereby the second piston in the direction orthogonal to the moving direction of the second piston 44 It regulates the movement range of 44.

In FIG. 2, a hole 424 is formed on the side of the fitting portion 423 of the first piston 42, and a cylindrical first buffer elastic body 90 is inserted into the hole 424. One end of the first buffer elastic body 90 protrudes from the hole 424 toward the second piston 44 in the state of the fluid pressure 0.

A cylindrical second buffer elastic body 100 is disposed on the outer periphery of the second projection 445 of the first piston 42. One end of the second buffer elastic body 100 protrudes toward the moving range restricting surface 454 side of the stopper 45 more than the tip end surface of the second protrusion 445 in the state of the fluid pressure 0.

The first buffer elastic body 90 and the second buffer elastic body 100 are made of a material having a significantly large amount of elastic deformation as compared to metal or hard resin, more specifically, rubber, and more specifically, for example, ethylene, propylene, and diene copolymer. It consists of polymerized rubber (EPDM).

Next, the operation of the brake device configured as described above will be described.

First, the operation of the portion excluding the stroke simulator 40 will be described based on FIG. If the brake pedal 10 is depressed while there is no abnormality in the brake device, the stroke sensor 20 detects that the brake pedal 10 is depressed and the second cut valve 61 is closed to close the conduit B.

Then, when the depression of the brake pedal 10 is released, the fact that the depression of the brake pedal 10 is released is detected by the stroke sensor 20, and the second cut valve 61 is opened to open the conduit B.

Next, the operation of the stroke simulator 40 according to the first embodiment will be described based on FIG.

When there is no abnormality in the brake device, for example, it is detected that the door of the vehicle has been opened, and the first cut valve 80 of the stroke simulator 40 is opened by an ECU (Electronic Control Unit) not shown. A is opened so that the brake fluid pressure is transmitted from the master cylinder 30 to the fluid pressure chamber 43 through the conduit A.

When the brake pedal 10 is operated, the brake fluid pressure transmitted to the fluid pressure chamber 43 acts on the first piston 42 to bias the first piston 42 in the X direction. Then, the first piston 42 starts moving in the X direction against the spring force of the first spring 46 and the second spring 47 as the brake fluid pressure rises.

At this time, at the initial stage when the first piston 42 starts moving in the X direction from the state where the first piston 42 is in the initial position without the brake pedal 10 being operated, the first inner diameter B mentioned above Is set to be larger than the second inner diameter C in a state in which the first piston 42 has moved by the predetermined distance A.

As a result, the pressing force between the cup seal 421 and the inner peripheral surface of the housing at the initial stage of operation of the brake pedal 10 can be increased as the brake pedal 10 is operated and the first piston 42 moves by a predetermined distance A. . Therefore, in the initial stage of operation of the brake pedal 10, the sliding resistance between the cup seal 421 and the inner peripheral surface of the housing 41 can be reduced, and the resistance to the driver's braking operation can be reduced, so that the brake feeling can be improved. . Furthermore, when the operating force of the driver is sufficiently increased with the operation of the brake pedal 10, the influence of the sliding resistance between the cup seal 421 and the inner peripheral surface of the housing is small. There is no problem in the increase of the circumferential surface and the pressing force, and the sealing property by the cup seal 421 can be reliably ensured by the above configuration.

Furthermore, during the movement of the first piston 42 in the X direction, the spring constant is maintained until the end surface of the fitting portion 423 of the first piston 42 abuts on the end surface of the first projection 444 of the second piston 44 Since the first spring 46 having a small value of d is mainly compressed, the amount of change of the pedal stroke with respect to the amount of change of the pedal operation force becomes large.

When the first piston 42 and the second piston 44 abut on each other, the tip of the second projection 445 of the second piston 44 of the first piston 42 and the second piston 44 is the movement range restricting surface 454 of the stopper 45. It moves integrally until it abuts on the At this time, the amount of change in the pedal stroke with respect to the amount of change in the pedal operation force with which the second spring 47 having a large spring constant is compressed is reduced.

Then, after the end face of the second projection 445 of the second piston 44 abuts on the movement range restricting surface 454 of the stopper 45, the pedal stroke does not change even if the pedal operation force increases.

When the second piston 44 moves, the second projection 445 of the second piston 44 is guided by the guide 455 of the stopper 45. As a result, the moving range of the second piston 44 in the direction orthogonal to the moving direction of the second piston 44 is restricted, and the inclination of the second piston 44 is prevented, so that the simulator characteristics are stabilized.

Further, the operation when an abnormality occurs in the brake device will be described based on FIG. For example, when an abnormality such as a failure of the hydraulic pressure source 70 occurs, the first cut valve 80, the pressure increasing valve 81, and the pressure reducing valve 82 are closed, and the second cut valve 61 is opened. In this state, when the brake pedal 10 is depressed, the brake fluid is supplied from the master cylinder 30 to the wheel cylinder 50 through the conduit B, and braking can be performed.

By the way, with the above configuration, when the operation of the brake pedal 10 is released, the first piston 42 and the second piston are axially moved in the Y direction by the biasing force of the first spring 46 and the second spring 47, respectively. Pressure is applied. Thereby, the first piston 42 and the second piston 44 return to the initial position.

The initial position of the first piston 42 is determined by the sliding resistance between the cup seal 421 and the inner peripheral surface of the housing 41. For this reason, the initial position of the first piston 42 is not constant due to the contact state of the cup seal 421 with the inner peripheral surface of the housing 41 and the variation in molding. As a result, at the initial stage of the operation of the brake pedal 10, the brake feeling is different each time the brake pedal 10 is operated, which may cause the driver to feel discomfort.

On the other hand, in the second embodiment of the present invention shown in FIG. 5, not only the taper portion 80 on the X direction side of the first pressing surface but also the Y direction side (hydraulic pressure chamber 43) of the cup seal 421 A tapered portion 81 is formed, and a third inner diameter in which the inner diameter of the housing 41 is smaller than the first inner diameter B is formed (see FIG. 2). The position of the tapered portion 81 can be arbitrarily set as the initial position of the first piston 42.

That is, since the sliding resistance between the cup seal 421 at the third inner diameter D and the inner peripheral surface of the housing 41 is larger than the sliding resistance between the cup seal 421 at the first inner diameter B and the inner peripheral surface of the housing 41, The axial movement of the first piston 42 toward the fluid pressure chamber 43 can be restricted. Therefore, the initial position of the first piston 42 when the operation of the brake pedal 10 is released is determined by the tapered portion 81 and the third inner diameter D. Thus, the initial position of the first piston 42 can be set to a constant position, so that the brake feeling can be made uniform at the initial stage of the operation of the brake pedal 10, and the brake feeling can be improved.

In the second embodiment, the second inner diameter and the third inner diameter have the same size, but the sizes of the second inner diameter and the third inner diameter may be different.

DESCRIPTION OF SYMBOLS 10 brake pedal 41 housing 42 1st piston 43 hydraulic pressure chamber 44 2nd piston 46 1st spring 47 2nd spring 70 pressing surface 80, 81 taper part A predetermined movement distance of piston B 1st inside diameter C 2nd inside diameter D 3rd Inner diameter

Claims (2)

A stroke simulator device for causing the brake pedal to generate a stroke having a size corresponding to the operating force of the brake pedal,
With the housing,
A first piston disposed slidably in a fluid tight manner in the housing;
A fluid pressure chamber formed on one end side of the first piston and supplied with a fluid pressure corresponding to the operating force of the brake pedal;
A second piston disposed at the other end of the first piston and movable integrally with the first piston;
An annular member is formed in the outer peripheral surface of the first piston, and an elastic member which is press-fit into the annular groove and which slidably presses the inner peripheral surface of the housing,
A first spring disposed between the first piston and the second piston and biasing the first piston in a direction in which the volume of the fluid pressure chamber decreases, and a direction in which the volume of the fluid pressure chamber decreases A second spring for biasing the second piston to
In a state where the brake pedal is not operated and the first piston is in the initial position, the inner circumferential surface of the housing has a first pressing surface on which the elastic member presses the inner circumferential surface of the housing.
The inner circumferential surface of the housing has a second pressing surface on which the elastic member presses the inner circumferential surface of the housing when the brake pedal is operated and the first piston is moved by a predetermined distance.
A stroke simulator device characterized in that a first inner diameter which is an inner diameter of the housing in the first pressing surface is larger than a second inner diameter which is an inner diameter of the housing in the second pressing surface. The stroke simulator device according to claim 1, wherein the hydraulic pressure chamber side of the housing is formed with a third inner diameter smaller than the first inner diameter at a predetermined distance from the elastic member.