JP2005053310A - Brake fluid pressure generating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress fluctuation of brake manipulated variable due to consumed fluid amount fluctuation and fluid pressure fluctuation of a brake circuit by simple structure to advantageously realize a desired stroke characteristic of a brake operation means, in a brake fluid pressure generating device having a boosting device. <P>SOLUTION: This device is provided with a negative type boosting device 21 having an input shaft 28 operated by a brake operation, a stroke simulator 29 for imparting stroke and reaction according to the brake manipulated variable to the input shaft 28 and a control valve 37, a master cylinder 22 for generating brake fluid pressure, and a pressure detecting member 23 for detecting fluid pressure of a pressure chamber 22b to apply the reaction according to the detected fluid pressure to a valve member 40 of the control valve 37. An input transmitted via a stroke simulator 29 and the reaction from the pressure detecting member 23 are opposed and received by the control valve 37 to balance the reaction in relation to the input. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a brake fluid pressure generator for a vehicle that adjusts an output of a booster with a control valve, and operates a master cylinder with the adjusted output to generate a brake fluid pressure according to a brake operation amount. , Function to prevent fluctuations in brake operation amount (operation stroke) and deterioration in operation feeling due to fluctuations in fluid consumption and fluid pressure in the brake circuit, and to optimize output hydraulic pressure at the initial stage of brake operation (so-called jumping) The present invention relates to a brake fluid pressure generator with a function).

  A brake fluid pressure generating device including a booster is configured to amplify a brake operation force with a booster and apply the amplified force to a master cylinder. As the booster, a negative pressure booster or a hydraulic booster is used. Some brake fluid pressure generators equipped with the booster have a structure in which the amount of brake pedal operation and the amount of fluid discharged from the master cylinder directly correspond to each other. When brake control, vehicle stability control (VSC), etc. are executed, the influence of the increase in the amount of liquid consumption of the brake circuit is reflected in the operation amount of the brake operation means, for example, the brake pedal, and the driver's operation feeling deteriorates. Unavoidable.

As a countermeasure against this problem, Patent Document 1 below discloses a brake fluid pressure in which a variation in brake operation amount is suppressed even when a fluid pressure control not performed by the driver's intention is executed and a consumed fluid amount in the brake circuit varies. Various forms of generators are introduced in detail.
JP 2002-173016 A

  FIG. 6 shows almost the same structure as that of FIG. Japanese Patent Application Laid-Open No. 2003-228561 provides a detailed description of this configuration, but it will be briefly described here.

A valve piston 5b (second valve element) that can move in the axial direction relative to the power plate 15a is disposed inside the power plate 15a, and an atmospheric pressure valve seat 5b ₃ provided in the first valve element integral with the input shaft 4; A control valve that adjusts the output of the power plate 15a by controlling the pressure in the variable pressure chamber (power chamber) 15b by the negative pressure valve seat 5b ₄ provided in the valve piston 5b and the valve body 5 disposed inside the valve piston 5b. Is configured.

  Further, springs (stroke-force conversion devices) 7 and 18 are provided between the valve piston 5b and the fixed shell (housing) 2 and between the valve piston 5b and the power plate 15a, respectively.

  In the illustrated brake fluid pressure generator, the power plate 15a receives the difference between the pressure in the variable pressure chamber 15b and the pressure in the constant pressure chamber (negative pressure chamber) 15c, and outputs a force obtained by amplifying the input. The master cylinder 16 generates a brake fluid pressure corresponding to the amount of brake operation, and the fluid pressure is supplied to the brake circuit (wheel cylinder 9 side). Further, the input shaft 4 receives the hydraulic pressure as a reaction force.

  The stroke of the input shaft 4 is substantially equal to the stroke of the valve piston 5b. The stroke of the input shaft 4 is determined by compressing the spring 7 to a position where the thrust generated in the valve piston 5 b by the pressure in the variable pressure chamber 15 b is balanced with the repulsive force of the spring 7. On the other hand, the reaction force when the brake pedal is operated is generated when the input shaft 4 receives the hydraulic pressure generated by the master cylinder 16 at the tip (the output hydraulic pressure of the master cylinder). Since it occurs according to the pressure in the chamber 15b, the relationship between the stroke of the brake pedal and the reaction force applied to the brake pedal can be set regardless of the amount of liquid consumed in the brake circuit.

  The brake hydraulic pressure generator disclosed in Patent Document 1 is a first valve element integrated with an input shaft 4 and a second valve element (valve piston) that enables relative movement in the axial direction with respect to the first valve element. 5b) is structured to move together in response to an input operation, so that it is necessary to eliminate fluctuations in the brake operation amount due to fluctuations in the amount of liquid consumed in the brake circuit, and a complicated stroke for controlling the position of the valve piston 5b- It is necessary to provide a force conversion device, which is disadvantageous in terms of cost and miniaturization.

  There is also a problem that there is no jumping function for increasing the output hydraulic pressure at the initial stage of the brake operation, and the output hydraulic pressure at the initial stage of the brake operation cannot be optimized.

  In order to advantageously realize the desired stroke characteristics of the brake operation means, the present invention makes it possible to suppress the fluctuation of the brake operation amount due to the consumption fluid amount fluctuation / hydraulic pressure fluctuation of the brake circuit with a simple structure. It is an object to further improve the performance of the brake fluid pressure generator by adding a jumping function to increase the initial output fluid pressure.

  In order to solve the above-described problems, in the present invention, an input shaft that is operated by a brake operation, a stroke simulator that applies a stroke and a reaction force according to the amount of brake operation to the input shaft, and an output of a booster are used for the brake. An input unit including a control valve that adjusts according to an operation amount of the operation unit, and an output unit that receives the output of the boosting unit are movable relative to the input unit, and receives an output of the output unit to receive a brake. A master cylinder that generates hydraulic pressure, and a pressure detection member that detects an output hydraulic pressure of the master cylinder and applies a reaction force corresponding to the detected hydraulic pressure to the control valve, and the control valve includes the stroke simulator The reaction force from the input shaft and the reaction force from the pressure detection member are received against each other to balance the reaction force against the input. In addition to this, there is further provided a movement resistance applying means for applying a movement resistance to the pressure detection member until the output hydraulic pressure of the master cylinder reaches a predetermined pressure to stop transmission of reaction force to the control valve. .

  The booster may be a negative pressure booster or a hydraulic booster.

  The movement resistance applying means may be a spring that applies a repulsive force in a direction opposite to the reaction force to the pressure detection member. However, when a spring is used, a gap is provided between the pressure detection member and the control valve. The gap is set so as not to disappear until the output hydraulic pressure of the master cylinder reaches a predetermined hydraulic pressure.

  In the case of using a movement resistance applying means that can surely stop the movement of the pressure detection member until the output hydraulic pressure of the master cylinder reaches a predetermined hydraulic pressure, the above gap is unnecessary.

  Although the reaction force applied to the control valve increases as the amount of fluid consumed by the brake circuit increases, the brake fluid pressure generator of this invention balances the reaction force against the input, so the fluctuation of the reaction force and the reaction force The displacement of the pressure detecting member due to the fluctuation of the pressure is kept small, and the change in the brake operation force and the change in the stroke of the input shaft (that is, the change in the brake operation amount) hardly occur due to the increase in the amount of liquid consumption of the brake circuit. Even when the hydraulic pressure in the brake circuit rises, fluctuations in the brake operation force and the brake operation amount are suppressed by the same action.

  In addition, when using a brake caliper that increases the amount of fluid supplied from the master cylinder and has low drag characteristics that aim to improve vehicle fuel efficiency and reduce brake vibration, the brake operation means can be operated with the same amount of braking. There is no impact.

  Furthermore, since the driver's brake feeling characteristics are uniquely determined by a stroke simulator interposed between the input shaft and the control valve, the brake feeling is affected even if the amount of liquid consumed in the brake circuit varies. Good brake feeling can be obtained.

  In addition, because of the action of the movement resistance applying means, the reaction force is not transmitted to the control valve until the output hydraulic pressure of the master cylinder reaches the predetermined hydraulic pressure, so the output hydraulic pressure can be increased without increasing the input at the initial stage of the brake operation. It is possible to impart jumping characteristics that enhance.

  FIG. 1 shows an embodiment of the brake fluid pressure generating device of the present invention. The illustrated brake fluid pressure generator operates a master cylinder with the output of a negative pressure booster to generate brake fluid pressure.

  In the figure, 20 is a brake pedal, 21 is a negative pressure booster, 22 is a master cylinder, 23 is a pressure detection member, 24 is a reservoir, and 25 is a brake circuit having a brake hydraulic pressure control device 26 and a wheel brake 27. .

  The negative pressure booster 21 includes an input shaft 28 that operates by receiving an operation force from the brake pedal 20, a stroke simulator 29 that applies a stroke and a reaction force according to the amount of brake operation to the input shaft 28, and an intake manifold of the engine. A constant pressure chamber 30 connected to a negative pressure source such as, a variable pressure chamber 31 into which air corresponding to the amount of brake operation is introduced during brake operation, and a fixed shell 32 (32a) that defines the constant pressure chamber 30 and the variable pressure chamber 31 from the outside. Is a negative pressure inlet), a power plate 33 that receives the pressure of the constant pressure chamber 30 and the pressure of the variable pressure chamber 31, a return spring 34 of the power plate 33, a stroke simulator 29, and a control valve 37 described later. Between the constant pressure chamber 30 and the variable pressure chamber 31, the spring 36 for urging the valve piston 35 backward, And a control valve 37 for adjusting the pressure.

A return force by a spring (not shown) is applied to the brake pedal 20 at the rotation fulcrum. The stroke simulator 29 is configured by retainers 29a and 29b arranged opposite to each other, and an elastic body 29c disposed between the retainers 29a and 29b. The elastic body 29c is preferably the one shown in the drawing, that is, the one in which the spring 29c- ₁ and the rubber member 29c- ₂ are used in combination so that the repulsive force against the brake operation amount increases from the middle.

  The valve piston 35 constituting the input unit including the input shaft 28, the stroke simulator 29, and the control valve 37 has an axial relative movement with the power plate 33 inside the cylindrical portion 33 a of the power plate 33 that is the output unit. It is inserted so as to be allowed, and is held at the position shown in the figure by the force of a spring 36 that is contracted between the power plate 33.

  The control valve 37 includes a negative pressure valve 38 that opens and closes a passage between the constant pressure chamber 30 and the variable pressure chamber 31, and an atmospheric valve 39 that opens and closes a passage between the variable pressure chamber 31 and the outside of the fixed shell 32. The negative pressure valve 38 is configured by an expandable / contractible valve body 39a disposed inside the valve piston 35 and a valve seat 38a formed in the valve piston 35. The atmospheric valve 39 includes the valve body 39a and the valve member 40. And a spring 39c that is contracted between the valve body 39a and the retainer 29b and biases the valve body 39a in the valve closing direction, and a spring that biases the valve member 40 and the valve body 39a backward. 39d.

  The valve member 40 can move relative to the valve piston 35 in the axial direction, and the negative pressure valve 38 and the atmospheric valve 39 are opened and closed by the displacement of the valve member 40.

  The power plate 33 advances by receiving the differential pressure generated between the variable pressure chamber 31 and the constant pressure chamber 30, and outputs a force obtained by amplifying the input. As a result, the master cylinder piston 22a compresses and pushes the return spring 22c, and a brake fluid pressure corresponding to the brake operation amount is generated in the pressure chamber 22b.

  The pressure detection member 23 detects the hydraulic pressure generated in the master cylinder 22 (output hydraulic pressure of the master cylinder) and applies a reaction force corresponding to the detected hydraulic pressure to the valve member 40. An elastic body (a spring in the figure is a spring) 41 as a movement counter-giving means is arranged between the pressure detection member 23 and the valve piston 35, and the elastic body 41 moves the pressure detection member 23 in the reaction force transmission direction. Adding resistance. In addition, a clearance 42 is provided between the pressure detection member 23 and the valve member 40 in an initial state where no brake operation is performed, and the repulsive force of the elastic body 41 is maintained until the output hydraulic pressure of the master cylinder 22 reaches a predetermined pressure. Thus, the gap 42 is maintained so that no reaction force is transmitted to the valve member 40.

  In the following, the operations when the illustrated brake fluid pressure generating device is in normal operation, when the amount of consumed fluid in the brake circuit varies, and when the negative pressure booster fails are described.

-During normal operation-
In the illustrated brake fluid pressure generating device, the atmospheric valve 39 is closed and the negative pressure valve 38 is opened as shown in FIG. Therefore, the constant pressure chamber 30 and the variable pressure chamber 31 communicate with each other and have the same pressure, and the power plate 33 is held in the illustrated initial position.

  When the brake pedal 20 is depressed from this state, the valve member 40 is pushed to the left in the drawing by the input transmitted via the stroke simulator 29, and the valve body 39a follows the valve member 40 and is shown in FIG. Thus, the negative pressure valve 38 is closed, and the communication between the constant pressure chamber 30 and the variable pressure chamber 31 is cut off. Thereafter, the valve member 40 is separated from the valve body 39 a, the atmospheric valve 39 is opened, and the atmosphere flows into the variable pressure chamber 31. For this reason, a differential pressure (pressure difference) is generated between the constant pressure chamber 30 and the variable pressure chamber 31, and the power plate 33 receiving the differential pressure advances to push the master cylinder piston 22a to the left in the figure. As a result, the master cylinder 22 operates to generate a hydraulic pressure in the pressure chamber 22b.

  The pressure detection member 23 receives the hydraulic pressure generated in the pressure chamber 22b at the tip and moves to the right in the figure. However, until the elastic body 41 is compressed by an amount corresponding to the size of the gap 42, the valve member as shown in FIG. Therefore, the reaction force is not transmitted to the valve member 40 of the control valve 37, and the atmospheric valve 39 is not closed during that time. Therefore, even if the jumping function is exhibited and the input from the brake pedal 20 is not increased. Air is introduced into the variable pressure chamber 31, the output of the negative pressure booster 21 is increased, and the output hydraulic pressure of the master cylinder 22 is increased.

  FIG. 4 shows the relationship between the braking effectiveness and the pedal effort (the pedal effort applied to the brake pedal 20) of the brake fluid pressure generating device of the present invention and the conventional device (comparative example) having no jumping function. Thus, if there is a jumping function, the effectiveness of the brake at the initial stage of the brake operation is improved.

  FIG. 5 shows the relationship between the braking effectiveness and the pedal effort when the elastic body 41 gives the movement resistance to the pressure detection member 23. As can be seen from FIG. 5, when the elastic body 41 is used as the movement resistance applying means, the braking effect becomes smooth.

  Next, when the brake operation force is increased and the gap 42 is absorbed and the pressure detection member 23 comes into contact with the valve member 40 to reach the state shown in FIG. 3, the reaction force from the master cylinder 22 is transmitted to the valve member 40. Thereafter, the control valve 37 opens the atmospheric valve 39 until the reaction force and the input from the brake pedal 20 are balanced, and when the input applied to the valve member 40 and the reaction force are balanced, the negative pressure valve 38 and the atmospheric valve 39 are closed.

  The valve piston 35 is maintained at the initial position by the force of the spring 36 regardless of the amount of advance of the power plate 33. The reaction force applied to the brake pedal 20 can be arbitrarily set by selecting the elastic body 29c.

In this normal operation, when the pedal depression force (the force applied to the brake pedal 20) is F1, the elastic coefficient of the elastic body 29c is k1, and the stroke of the input shaft 28 is L1, the relationship is expressed by Expression (1). Become a thing.
L1 = F1 / k1 (1)
Further, the balance formula of the force applied to the power plate 33 is as follows: L2 is the stroke of the power plate 33, F2 is the output of the power plate 33, M1 is the amount of liquid consumed by the brake circuit, and P1 is the hydraulic pressure generated in the pressure chamber 22b. The relationship between them is expressed by the equation (2).
M1 = (F2 / P1) × L2 (2)
Here, when the cross-sectional area (pressure receiving area) of the master cylinder piston 22a is S22 and the cross-sectional area (pressure receiving area) of the pressure detecting member 23 is S23, the area ratio k2 is
k2 = S23 / S22 (3)
It becomes. Regardless of the amount of liquid consumed by the brake circuit, the control valve 37 adjusts the amount of air introduced into the variable pressure chamber 31 so that the pressure applied to the pressure detection member 23 and the power plate 33 becomes equal in proportion to the area ratio k2. Therefore, when the consumed liquid amount M1 in the above equation (2) is large, the amount of air introduced into the variable pressure chamber 31 is increased, and the stroke L2 of the power plate 33 is increased to balance the input and the reaction force. Thus, the pedal depression force F1 and the stroke L1 (that is, the brake operation amount) of the input shaft 28 do not change.

-When the fluid consumption and fluid pressure of the brake circuit vary-
For example, when the brake fluid pressure control device 26 controls the brake fluid pressure Pw on the wheel brake 27 side with the execution of regenerative cooperative brake control, vehicle stability control (VSC), etc., the amount of fluid consumed at that time is When M2, the consumed liquid amount M1 of the above formula (2) changes to M2, and the control valve 37 adjusts the differential pressure between the constant pressure chamber 30 and the variable pressure chamber 31 according to the change amount, and the power plate The output F2 of 33 is changed.

  For example, if the amount of fluid consumed by the brake circuit increases from M1 to M2, the amount of fluid in the pressure chamber 22b increases and the fluid pressure P1 in the pressure chamber 22b increases and is transmitted from the pressure detection member 23 to the valve member 40. The reaction force also increases, but in this situation, the valve member 40 slightly opens the negative pressure valve 38 with the atmospheric valve 39 closed. For this reason, the pressure in the variable pressure chamber 31 is reduced, the power plate 33 is retracted, the output F2 of the power plate 33 is reduced, and the hydraulic pressure P1 and the reaction force due to the hydraulic pressure P1 are reduced.

  Thereby, the input applied to the valve member 40 and the reaction force are balanced in a state where there is almost no variation in the pedal depression force F1 and the stroke L1 of the input shaft 28. The same applies when the hydraulic pressure of the brake circuit fluctuates when there is no input fluctuation.

  As can be seen from the relationship between the stroke and pedal depression force and the stroke and brake effectiveness in FIG. 4, the brake hydraulic pressure generating device of the present invention can ensure the same brake effectiveness with a small operation amount. The effectiveness is also demonstrated when using a brake caliper with low drag characteristics that aims to improve or reduce brake vibration.

−In case of failure of boost function−
When the brake pedal 20 is depressed, the stroke simulator 29 moves to the left in the figure to push the valve member 40, the valve member 40 hits the valve piston 35, and the input is transmitted to the valve piston 35. Since the force of the spring 36 is weaker than the force of the return spring 34, the valve piston 35 moves to the left in the drawing together with the stroke simulator 29 and the control valve 37, and pushes the power plate 33. At this time, no negative pressure is introduced into the constant pressure chamber 30 and the assisting force by the booster 21 cannot be obtained, but the brake fluid pressure can be generated by the operating force of the driver.

  The pressure detection member 23 is provided with a bulging portion 23a so that the valve piston 35 can move forward in the figure while leaving the power plate 33 in the initial position, and the brake operation force is reduced when the boosting function is lost. It can also be transmitted directly to the master cylinder piston 22a via the detection member 23.

Sectional drawing of the non-operation state which shows embodiment of the brake fluid pressure generator of this invention The figure which shows the operating state of the brake operation initial stage of the brake fluid pressure generator of FIG. The figure when the balance control of the input and reaction force of the brake hydraulic pressure generator of FIG. 1 is made Diagram showing input shaft stroke, pedal effort and braking effectiveness The figure which shows the pedal depression force and the effect of the brake when the elastic body is used as the movement resistance giving means Sectional drawing which shows an example of the conventional brake fluid pressure generator

Explanation of symbols

20 brake pedal 21 negative pressure booster 22 master cylinder 22a master cylinder piston 22b pressure chamber 22c return spring 23 pressure detection member 23a bulging portion 24 reservoir 25 brake circuit 26 brake hydraulic pressure control device 27 wheel brake 28 input shaft 29 stroke simulator 29a, 29b Retainer 29c Elastic body 29c _-1 Spring 29c- ₂ Rubber member 30 Constant pressure chamber 31 Variable pressure chamber 32 Fixed shell 32a Negative pressure inlet 33 Power plate 33a Cylindrical portion 34 Return spring 35 Valve piston 36 Spring 37 Control valve 38 Negative pressure valve 38a Valve seat 39 Atmospheric valve 39a Valve body 39b Valve seat 39c, 39d Spring 40 Valve member 41 Elastic body 42 Gap

Claims (1)

  An input shaft that is operated by a brake operation, a stroke simulator that applies a stroke and a reaction force according to a brake operation amount to the input shaft, a control valve that adjusts an output of a booster unit according to an operation amount of the brake operation unit, And a master cylinder that generates a brake fluid pressure by receiving the output of the output unit, and an output unit that receives the output of the booster is movable relative to the input unit. A pressure detection member that detects an output hydraulic pressure and applies a reaction force corresponding to the detected hydraulic pressure to the control valve, and the control valve transmits the input transmitted from the input shaft via the stroke simulator, and It is configured to counteract the reaction force from the pressure detection member and balance the reaction force against the input, and the output hydraulic pressure of the master cylinder is The pressure sensing member to transfer resistance to addition reaction force of the movement resistance applying means has a brake fluid pressure generating device comprises a stop transfer to the control valve to a pressure of.

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