JP2013199231A - Hydraulic brake device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate deterioration in brake operation feeling of a by-wire type brake device for a vehicle.SOLUTION: An input piston 14 and a master piston 20 are provided in a housing 16 so as to be mutually movable via a partition wall 17a and a first fluid chamber C1, and pressure regulation is applied to the master piston 20 by a second fluid chamber C2. The master piston 20 includes front and rear large-diameter and small-diameter pistons 21a and 21b which are fitted to each other in such a manner as to be mutually and longitudinally movable with a constant stroke L. When the large-diameter piston 21a advances by the pressure regulation to the second fluid chamber C2, the inflow of a brake fluid into the first fluid chamber C1 (a transition of the brake fluid) occurs on the basis of contraction of a fourth fluid chamber C4 via piping 30, only the large-diameter piston 21a moves at the initial stage of the shift of the brake fluid and impact pressure caused by the pressure regulation does not act on the small-diameter piston positioned in the first fluid chamber. This eliminates the risk of making operation feeling deteriorated by a change in the hydraulic pressure of the first fluid chamber C1, associated with a change in the capacity of the fourth fluid chamber due to the impact pressure and the movement of the master piston.

Description

  The present invention relates to a hydraulic brake device for a vehicle, and more particularly, to a brake device capable of ensuring a good operation feeling (so-called pedal feeling) in a structure capable of executing regenerative cooperative braking and automatic braking.

  The hydraulic pressure supplied from the high-pressure hydraulic pressure source is adjusted to a value according to the driver's brake operation by the pressure adjustment device, or a value set by the electronic control unit regardless of the driver's brake operation. There is a by-wire hydraulic brake device for a vehicle that can generate a brake hydraulic pressure by assisting the operation of a master piston of a master cylinder with pressure (see Patent Document 1, paragraphs 0062 to 0100, FIGS. 3 and 4).

  An example of such a hydraulic brake device for a vehicle is a target control system in which an input piston (see input piston 413 in FIG. 3 of Patent Document 1) that moves forward in response to a brake operation force and a hydraulic pressure supplied from a high-pressure hydraulic pressure source are controlled. The pressure adjusting device (see the same hydraulic pressure control valve 434) that adjusts the hydraulic pressure necessary to obtain power and sends it to the third hydraulic pressure chamber (see the rear hydraulic pressure chamber R3), and the adjusted hydraulic pressure A master cylinder (see reference numeral 411) for driving the master piston (see intermediate piston 414) to generate brake fluid pressure is provided.

  The input piston is inserted into a hole opened at the rear end of the master piston so as to be slidable in the axial direction, and the front end of the input piston is disposed between the piston chambers (refer to Patent Document 1 in FIG. 3). (See reference R5). Also, the rear end of the master piston faces the third hydraulic pressure chamber, and the inner peripheral surface of the hole of the master piston and the outer periphery of the input piston are between the inter-piston chamber and the third hydraulic pressure chamber in the master piston. And a high pressure seal (seal member 463) interposed therebetween.

JP 2010-929 A

  In the vehicle hydraulic brake device, when the hydraulic pressure adjusted by the pressure adjusting device is introduced into the third hydraulic pressure chamber, the master piston receives the hydraulic pressure on the back surface and moves forward. At this time, the input piston moves forward by being dragged to the master piston by the sliding resistance due to the high pressure seal interposed between the master piston and the input piston, so that the brake operation reaction force applied to the brake pedal becomes the brake operation amount. The operation feeling of the brakes deteriorates due to incompatibility.

  Therefore, an object of the present invention is to solve the problem of deterioration in operation feeling in the by-wire type vehicle brake device proposed by the above-mentioned Patent Document 1.

  In order to solve the above-described problems, the present invention provides a vehicle hydraulic brake device including a liquid chamber formed between the master piston and a housing and a liquid chamber between the input piston and the master piston. When the master piston moves forward by receiving the pressure adjustment, the brake fluid (fluid) is transferred to the latter fluid chamber based on the volume reduction of the former fluid chamber. Inflow (brake fluid is transferred), the fluid pressure fluctuation of the latter fluid chamber is eliminated (to achieve fluid pressure equilibrium), and the fluctuation of the input piston is eliminated.

  Next, the hydraulic fluid fluctuation in the latter fluid chamber can be suppressed by the brake fluid transfer by the piping, but at the initial stage, the movement of the master piston is caused by the operation of the electromagnetic on-off valve, the flow resistance, and the flow resistance of the piping. There is a delay in the transition of the brake fluid that suppresses the fluid pressure fluctuation in the latter fluid chamber due to the above, and there is a risk that the operation feeling will be deteriorated due to the fluid pressure fluctuation in the fluid chamber based on the delay. Normally, the master piston moves smoothly. However, at the initial stage of pressure regulation, the master piston moves due to the impact pressure caused by the pressure regulation, causing the volume fluctuation of the latter liquid chamber, and again, the operation of the brake applied to the brake pedal is counteracted. The force does not correspond to the amount of brake operation, and the brake operation feeling may deteriorate.

  Therefore, according to the present invention, the master piston that receives the pressure regulation is constituted by the front and rear members, and the two members are fitted to each other so as to be able to move by a fixed stroke in the front-rear direction. Is moved so that the impact pressure does not act on the rear member located in the latter liquid chamber so that it does not move, so that the impact pressure and fluid pressure fluctuations do not occur.

  Note that when the front member moves by a fixed stroke and moves integrally with the rear member, the brake fluid transfer by the piping is also in a smooth operating state, so there is no fear that the brake operation feeling will deteriorate. The fixed stroke prevents the impact pressure and the hydraulic pressure from fluctuating. Therefore, a movement amount (stroke) at which the impact pressure or the like does not occur is appropriately set by an experiment or the like.

  As a configuration of the present invention, the hydraulic pressure supplied from the high-pressure hydraulic pressure source is necessary to obtain a value corresponding to the driver's brake operation with the pressure regulator or a target braking force set by the electronic control unit. In a by-wire type hydraulic brake system for a vehicle that supplies a brake fluid pressure to a wheel cylinder by operating a master cylinder with the regulated fluid pressure and generating a brake fluid pressure, In addition, an input piston that moves forward in response to a brake operation force and a master piston that moves forward by pressure regulation are provided movably with respect to each other via a first liquid chamber between them and a partition on the inner surface of the housing. Consists of two members, a front and rear large-diameter piston and a small-diameter piston. Both large and small-diameter pistons are fitted to each other so that they can move in a fixed stroke in the front-rear direction. Ton penetrates the partition wall in a fluidly movable manner and protrudes into the first liquid chamber to form a second liquid chamber into which the pressure adjusting liquid flows between the rear end surface of the large diameter piston and the partition wall. It is possible to adopt a configuration in which a fourth liquid chamber is provided between the housings and the fourth liquid chamber and the first liquid chamber are communicated with each other through a pipe having an electromagnetic on-off valve.

  For example, the large-diameter piston and the small-diameter piston can be moved in a fixed stroke by fitting the small-diameter piston into the large-diameter piston so that the small-diameter piston can be moved in the front-rear direction. A gap is formed in the gap, and a locking portion is provided in the gap.When the large-diameter piston moves by the fixed stroke, both pistons are locked via the locking portion to move integrally. Can be adopted. The latching part should just be provided in either one of both pistons, and a space | gap can also be formed in only one or both of both pistons.

  The vehicle hydraulic brake device according to the present invention is a by-wire type that operates in a state where the master piston receives the hydraulic pressure (assist pressure) introduced into the second fluid chamber and is disconnected from the input piston. And automatic braking can be performed.

  Further, the first liquid chamber and the fourth liquid chamber are connected by a pipe having an electromagnetic on-off valve, and when the master piston moves forward by receiving the pressure adjustment, the volume of the fourth liquid chamber is passed through the pipe. The brake fluid based on the reduction can be caused to flow into the first fluid chamber (transfer to the brake fluid), so that the fluid pressure variation in the first fluid chamber can be eliminated and the variation of the input piston can be eliminated. For this reason, there is very little possibility of deteriorating the operation feeling due to the volume change of the first liquid chamber accompanying the volume change of the fourth liquid chamber due to the movement of the master piston.

  At that time, the master piston is composed of front and rear large and small diameter pistons, and only the large diameter piston is moved at the beginning of the brake fluid transfer, and the impact pressure does not act on the small diameter piston located in the first fluid chamber. Therefore, the deterioration of the operation feeling at the beginning of the transition of the brake fluid through the pipe is unlikely to occur.

1 shows an embodiment of a hydraulic brake device for a vehicle according to the present invention, in which (a) is an overall sectional view, and (b) is a partial action explanatory view.

  Hereinafter, an embodiment of a hydraulic brake device for a vehicle according to the present invention will be described with reference to FIGS. 1 (a) and 1 (b) of the accompanying drawings. The vehicle hydraulic brake device shown in FIG. 1 includes a brake hydraulic pressure generating device 1, a stroke simulator 2 that generates an operation reaction force according to a brake operation amount, and a connection of the stroke simulator 2 to the brake hydraulic pressure generating device 1. An electromagnetic on-off valve 3 that switches the state, a wheel cylinder 4 that operates with the hydraulic pressure generated by the brake hydraulic pressure generator 1 to apply braking force to each wheel, and a brake hydraulic pressure generator 1 that supplies the wheel cylinder 4 It has an ABS unit 5 that adjusts the brake fluid pressure as necessary.

  Further, a high-pressure hydraulic pressure source 6, a pressure adjusting device 7 that adjusts the hydraulic pressure supplied from the hydraulic pressure source 6 to a hydraulic pressure necessary to obtain a target braking force, and a discharge path to the reservoir 10 are provided. A target braking force is set on the basis of information from the electromagnetic on-off valve 8 that opens and closes and various known sensors that detect the operation state of the brake and the behavior of the vehicle, and a necessary pressure adjustment command is issued to the pressure adjusting device 7. An electronic control unit (ECU) 9 is included. The electronic control unit 9 sets a target braking force based on information from known sensors and various sensors that detect the operation state of the brake and the behavior of the vehicle, and from the high-pressure fluid pressure source 6 to the second fluid chamber C2. A command is issued to the pressure adjusting device 7 so as to adjust the introduced hydraulic pressure to the hydraulic pressure necessary to obtain the target braking force. The electronic control unit 9 issues a pressure adjustment command to the ABS unit 5 as necessary.

  The brake hydraulic pressure generator 1 includes a brake pedal 11, a return spring 12 that urges the brake pedal 11 in the return direction, an input rod 13 connected to the brake pedal 11, and the brake pedal 11 via the input rod 13. The input piston 14 that moves forward in response to the transmitted brake operation force and the tandem master cylinder 15 are combined.

  The master cylinder 15 has a housing 16 in which a master piston and a fixed partition member 17 are incorporated. The input piston 14 penetrates through the partition member 17 in a fluid-tight manner, and a first liquid chamber (first reaction chamber) whose volume changes in accordance with the amount of advance and retreat of the input piston 14 is passed through the penetrating member 17. A force chamber) C1 is provided, and the stroke simulator 2 is connected to the first liquid chamber C1 via an electromagnetic on-off valve 3 that seals and releases the first chamber. A second liquid chamber (boost chamber) C2 is provided in front of the first liquid chamber C1 via a partition wall 17a formed at the tip of the partition member 17. Further, a third liquid chamber C3 having an atmospheric pressure communicating with the reservoir 10 is provided on the outer periphery on the rear side of the partition member 17.

  The master piston includes a primary piston 20 and a secondary piston 18. Further, the primary piston 20 is composed of a front-side large-diameter piston 21a and a rear-side small-diameter piston 21b, and the small-diameter piston 21b is fitted into the large-diameter piston 21a so as to be movable in the front-rear direction. In the fitting portion, an outer peripheral surface of the small-diameter piston 21b and an inner peripheral surface of the large-diameter piston 21a are squeezed (small or large diameter) to form a gap 22 communicating with the following fourth liquid chamber C4. When the locking pin 23 is provided in the gap 22 and the large-diameter piston 21a moves by a constant stroke L, both the pistons 21a and 21b are locked and moved integrally through the locking pin 23. Since the constant stroke L prevents the impact pressure and the hydraulic pressure from fluctuating, an amount of movement that does not cause the impact pressure or the like is appropriately set by experiment or the like.

  The locking pin 23 is formed with a radial hole in the small diameter portion (the inner peripheral surface of the gap 22) of the small diameter piston 21b, and an elastic body such as a coil spring is loaded into the hole, and the elastic body protrudes and retracts from the hole. Make it free. For this reason, when the small-diameter piston 21b is fitted into the large-diameter piston 21a, the locking pin 23 is pushed into the hole, enters into the large-diameter piston 21a, and protrudes into the gap 22, and then projects behind the gap 22 in the large-diameter piston 21a. It can be locked to the wall.

  Further, the back surface of the large diameter portion of the large diameter piston 21a (the portion into which the small diameter piston 21b is fitted) faces the second liquid chamber C2, and the fourth liquid chamber (second reaction force chamber) C4 is formed on the outer periphery of the large diameter piston 21a. Is provided. The fourth liquid chamber C4 and the first liquid chamber C1 are communicated with each other by a pipe 30 through which the electromagnetic on-off valve 3 led out from the housing 16 is interposed. Further, the volume of the fourth liquid chamber C4 decreases as the primary piston 20 (large diameter piston 21a) moves forward, while the first liquid chamber C1 moves forward of the primary piston 20 (small diameter piston 21b). Accordingly, the volume of the primary piston 20 is increased and the diameter of the portion related to the increase / decrease in the volume of the primary piston 20 (the diameters of the large-diameter piston 21a and the small-diameter piston 21b in front of the intermediate large-diameter portion) is the fourth liquid chamber at this time. The volume reduction amount of C4 and the volume expansion amount of the first liquid chamber C1 are set to be equal. For this reason, as the volumes of both the liquid chambers C1 and C4 increase or decrease, the brake fluid flows out from one liquid chamber into the other liquid chamber via the pipe 30, and the liquid pressures in both the liquid chambers C1 and C4 are balanced. To do.

  The master cylinder 15 (housing 16) further includes a return spring 19a for returning the primary piston 20 (large-diameter piston 21a) and the secondary piston 18, and a cup seal 19b for sealing the outer periphery of each piston. 18 and 20 pressurize the brake fluid in the hydraulic chambers PC1 and PC2 to generate the brake fluid pressure. This is a well-known structure.

The ABS unit 5 includes a pressure reducing solenoid valve (not shown) for reducing the hydraulic pressure of the wheel cylinder 4 when necessary, and a pressure increasing solenoid valve (not shown) for increasing the hydraulic pressure of the wheel cylinder 4 when necessary. It is a pressure regulating unit having a known structure.
The hydraulic pressure source 6 also has a known structure in which a pump 6a driven by a motor and a pressure accumulator 6b are combined.

  The pressure adjusting device 7 moves an internal valve body (not shown) to a position corresponding to the magnitude of the pilot pressure by the pilot pressure introduced from the output path of the master cylinder 15 through the pilot line 7a. The opening degree is adjusted, and the hydraulic pressure supplied from the hydraulic pressure source 6 is adjusted to a value corresponding to the output pressure of the master cylinder 15 by pressure increase / decrease control, and supplied to the second fluid chamber C2. This is also a well-known structure.

Due to the operation of the pressure adjusting device 7, the hydraulic pressure supplied from the hydraulic pressure source 6 becomes the hydraulic pressure set by the electronic control device 9 (the assist pressure corresponding to the brake operation when the normal brake or the regenerative cooperative brake is executed). The adjusted hydraulic pressure (pressure adjustment) is introduced into the second liquid chamber C2 as an assisting pressure. The master cylinder 15 is actuated by the hydraulic pressure and the hydraulic pressure in the first hydraulic chamber C1 to generate a brake hydraulic pressure necessary for generating a target braking force.
In the figure, the element with the symbol P is a hydraulic pressure sensor that detects the hydraulic pressure at a required location.

  In the vehicular hydraulic brake device of FIG. 1 configured as described above, when the regenerative coordination brake is executed, the electromagnetic on-off valve 8 is closed as the brake pedal 11 is depressed. Further, the electromagnetic on-off valve 3 is opened, and the first liquid chamber C1 and the fourth liquid chamber C4 are in communication with each other. Under this condition, the hydraulic pressure from the hydraulic pressure source 6 that has been adjusted to a value corresponding to the brake operation amount by the pressure adjusting device 7 is introduced into the second fluid chamber C2, and is introduced into the second fluid chamber C2. The primary piston 20 that has received the assisting pressure moves forward, and the secondary piston 18 also moves forward with the advance, and the master cylinder 15 operates to generate brake fluid pressure in the hydraulic chambers PC1 and PC2.

  When the primary piston 20 moves forward, first, the large-diameter piston 21a moves forward by pressure regulation, and the volume of the fourth liquid chamber C4 decreases accordingly. By this volume reduction, the brake fluid in the fourth fluid chamber C4 escapes to the first fluid chamber C1 via the pipe 30.

At this time, since the small-diameter piston 21b is separated from the large-diameter piston 21a, initially, the small-diameter piston 21b does not move forward with the advancement of the large-diameter piston 21a. The pressure is not transmitted to the first liquid chamber C1. Further, as the large-diameter piston 21a advances, the volume of the fourth liquid chamber C4 is reduced. However, since the fourth liquid chamber C4 communicates with the gap 22, as shown in FIG. The diameter piston 21a is separated from the small diameter piston 21b, and a gap is generated between them. Due to the formation of this gap, the brake fluid in the fourth fluid chamber C4 flows into the gap, and the increase in fluid pressure due to the volume reduction of the fourth fluid chamber C4 is suppressed. The volume reduction amount of the fourth liquid chamber C4 is preferably set equal to or larger than the gap volume.
By these actions, an increase in the fluid pressure in the fourth fluid chamber at the initial stage of pressure regulation is suppressed, and the impact pressure is not transmitted to the first fluid chamber C1, and there is no fear of deterioration of the brake operation feeling due to the impact pressure. .

  Next, as shown in FIG. 1B, when the large-diameter piston 21a moves forward by a stroke L relative to the small-diameter piston 21b, the locking pin 23 comes into contact with the rear wall of the gap 22 of the large-diameter piston 21a ( And the pistons 21a and 21b move forward together. At the time of this advancement, the volume reduction amount of the fourth liquid chamber C4 and the volume expansion amount of the first liquid chamber C1 are set to be equal, and the brake fluid in the fourth liquid chamber C4 passes through the pipe 30 smoothly. Since it flows into the liquid chamber C1, the volume increase of the first liquid chamber C1 and the inflow of brake fluid according to the volume decrease of the fourth liquid chamber C4 are smoothly performed (brake fluid escapes). For this reason, the fluctuation | variation of the brake operation reaction force added to the brake pedal 11 does not arise, and there is no fear of deterioration of the brake operation feeling.

  In this way, braking is performed with the master cylinder 15 disconnected from the input piston 14, so that the primary piston 20 (large-diameter piston 21a when the hydraulic pressure is introduced from the hydraulic pressure source 6 to the second hydraulic chamber C2 is used. The dragging of the input piston 14 due to) does not occur. Further, the fourth liquid chamber C4 and the first liquid chamber C1 are communicated so that the volume reduction amount of the fourth liquid chamber C4 accompanying the movement of the primary piston 20 and the volume expansion amount of the first liquid chamber C1 are equal. Thus, the reaction force applied to the brake pedal 11 corresponds to the amount of brake operation, and the brake operation feeling is improved.

  Further, the primary piston 20 is constituted by front and rear large and small diameter pistons 21a and 21b, and at the initial advance of the primary piston 20 (large diameter piston 21a), only the large diameter piston 21a is moved to the first liquid chamber C1. Since the small-diameter piston 21b is not moved by impact pressure due to pressure regulation, it does not move, so that the operation feeling at the beginning of the transition of the brake fluid through the pipe 30 is hardly deteriorated.

  When the electrical system fails, the movement of the input piston 14 based on the amount of depression of the brake pedal 11 with the electromagnetic on-off valve 3 closed, the electromagnetic on-off valve 8 opened, and the first liquid chamber C1 sealed. Thus, the primary piston 20 (large-diameter piston 21a) is operated by the hydraulic pressure in the first liquid chamber C1, and the brake hydraulic pressure depending on the brake operation force of the driver is generated by the master cylinder 15. Therefore, safety is ensured.

  In this embodiment, the locking portion is constituted by the pin 23. However, for example, other members such as a ball that can perform the locking action may be used, and the locking portion may be provided on the large-diameter piston 21a side. The gap 22 can also be formed in only one of the pistons 21a and 21b. When provided only on one side, the locking portion is provided on the member on the side where the gap 22 is not provided.

DESCRIPTION OF SYMBOLS 1 Brake fluid pressure generator 2 Stroke simulator 3, 8 Electromagnetic on-off valve 4 Wheel cylinder 5 ABS unit 6 Fluid pressure source 7 Pressure regulator 9 Electronic controller 10 Reservoir 11 Brake pedal 13 Input rod 14 Input piston 15 Master cylinder 16 Housing 17 Partition member 17a Partition 18 Secondary piston 20 of master piston Primary piston 21a of master piston Large diameter piston 21b of primary piston Small diameter piston 22 of primary piston Air gap 23 Locking pin (locking portion)
C1 First liquid chamber (first reaction force chamber)
C2 Second liquid chamber (boost chamber)
C3 Third liquid chamber C4 Fourth liquid chamber (second reaction force chamber)

Claims (2)

To obtain the hydraulic pressure supplied from the high-pressure hydraulic pressure source (6) in accordance with the brake operation of the driver by the pressure regulating device (7) or the target braking force set by the electronic control unit (9) A by-wire type vehicle that adjusts the pressure to a required value, operates the master cylinder (15) with the adjusted hydraulic pressure to generate the brake hydraulic pressure, and supplies the brake hydraulic pressure to the wheel cylinder (4). Hydraulic brake device for
In the housing (16), an input piston (14) that moves forward by receiving a brake operation force and a master piston (20) that moves forward by the pressure regulation are provided in a first liquid chamber (C1) between the two (14, 20). ) And a partition (17a) on the inner surface of the housing (16), and the master piston (20) is composed of two members, a front and rear large-diameter piston (21a) and a small-diameter piston (21b). The large and small diameter pistons (21a, 21b) are fitted to each other so as to be movable in a predetermined stroke (L) in the front-rear direction, and the small diameter piston (21b) penetrates the partition wall (17a) so as to be movable in a liquid-tight manner. The second liquid chamber (C2) into which the pressure adjusting liquid flows is formed between the rear end surface of the large-diameter piston (21a) and the partition wall (17a). , The large diameter pipe A fourth liquid chamber (C4) is provided between the ton (21a) and the housing (16), and the fourth liquid chamber (C4) and the first liquid chamber (C1) are interposed by an electromagnetic on-off valve (3). A hydraulic brake device for a vehicle communicated with a pipe (30).   The small-diameter piston (21b) is fitted into the large-diameter piston (21a) from the rear end face so as to be movable in the front-rear direction, and a gap (22) communicating with the fourth liquid chamber (C4) is formed in the fitting portion. (22) When the locking part (23) is provided in the large diameter piston (21a) and the fixed stroke (L) moves, both pistons (21a, 21b) are moved through the locking part (23). The hydraulic brake device for a vehicle according to claim 1, wherein the hydraulic brake device is engaged and moved integrally.

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