JP2005053307A - 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 operation means by simple structure, and to make a function for enhancing brake fluid pressure obtained by a driver's brake operating force when a boosting function fails. <P>SOLUTION: This device is provided with a negative pressure type boosting device 21 having an input shaft 28, a stroke simulator 29 for imparting stroke and reaction according to 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 reaction according to the detected fluid pressure to a valve member 40 of the control valve 37. The control valve 37 opposes and receives an input transmitted via a stroke simulator and reaction from the pressure detecting member 23 to balance the reaction in relation to the input, and advances a valve piston 35 by leaving a power plate 33 at an initial position when the boosting function fails to directly apply the input to a master cylinder piston 22a via the pressure detecting member 23. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  This invention adjusts the output of a booster with a control valve, operates a master cylinder with the adjusted output, and generates a brake fluid pressure according to the amount of brake operation. , Prevents 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 at the same time, can be obtained by the driver's brake operation force when the boost function fails The present invention relates to a brake fluid pressure generator to which a function for increasing brake fluid pressure is added.

  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. 5 shows almost the same structure as 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.

  Further, when the boosting function failure in which negative pressure is not introduced into the constant pressure chamber 15c, the return spring (not shown) of the spring 7 and the power plate 15a is compressed to transmit the driver's brake operation force to the master cylinder piston 16a. There was also a problem that the brake fluid pressure obtained due to transmission loss of brake operation force was lowered.

  In order to advantageously realize the desired stroke characteristics of the brake operating means, the present invention makes it possible to suppress the fluctuation of the brake operation amount due to the fluctuation of the consumption fluid amount and the fluid pressure of the brake circuit with a simple structure, and at the same time The task is to add a function to increase the brake fluid pressure obtained in the event of functional failure.

  In order to solve the above 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, A power piston that amplifies and outputs the input, and a control valve that adjusts the output of the power piston in accordance with the operation amount of the brake operating means, and the input includes the input shaft, the stroke simulator, and the control valve. And a power cylinder in which the power piston is axially movable, a master cylinder for generating brake fluid pressure by applying an output of the booster to the master cylinder piston, and an output fluid of the master cylinder A pressure detecting member that detects a pressure and applies a reaction force corresponding to the detected hydraulic pressure to the control valve. A control valve receives and counteracts an input transmitted from the input shaft via the stroke simulator and a reaction force from the pressure detection member to balance the reaction force against the input, and the control valve The input applied to is directly transmitted to the master cylinder piston via the pressure detection member.

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

  In addition, the master cylinder has two master cylinder pistons with different outer diameters arranged in series, and when the device is normal, the two master cylinder pistons are simultaneously pushed by the output of the booster, and the booster function is lost. Sometimes, a driver that pushes and moves the small-diameter master cylinder piston with the driver's brake operation force may be used.

  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, when the boost function is lost, the input applied to the control valve is transmitted directly to the master cylinder piston without going through the power piston, so there is no power transmission loss due to the return spring of the power piston. High brake fluid pressure can be generated.

  FIG. 1 shows an embodiment (Example 1) of the brake fluid pressure generator 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 that includes the input shaft 28, the stroke simulator 29, and the control valve 37 and constitutes the input unit has an axial relative movement with the power plate 33 inside the cylindrical portion 33 a of the power plate 33 that is a power piston. 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 is a power piston, and advances by receiving a 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. A bulging portion 23 a is formed in the middle of the length of the pressure detecting member 23, and the bulging portion 23 a is brought into contact with the rear portion of the master cylinder piston 22 a to receive the input received by the valve member 40 via the pressure detecting member 23. It can be directly transmitted to the piston 22a.

  The valve member 40 receives the reaction force and the input applied from the input shaft 28 via the stroke simulator 29, and between the constant pressure chamber 30 and the variable pressure chamber 31 so that the reaction force is balanced against the input. Adjust the differential pressure to be generated.

FIG. 2 shows a second embodiment. In this brake fluid pressure generating device, the piston of the master cylinder 220 is divided into two parts, a large master cylinder piston 22a- ₁ having an outer diameter of φA and a small master cylinder piston 22a- _{2 having} an outer diameter of φB, and a return spring 22c. _The large-diameter master cylinder piston 22a- ₁ receiving the force of _-1 receives the brake fluid in the first pressure chamber 22b- ₁ , and the small-diameter master cylinder piston 22a- ₂ receives the force of the return spring 22c _- 2. Each brake fluid in the pressure chamber 22b- ₂ is pressurized. The large-diameter master cylinder piston 22a- ₁ and the small-diameter master cylinder piston 22a- ₂ are arranged in series. When a force is applied from the power plate 33 to the large-diameter master cylinder piston 22a- ₁ , the pressure in the first pressure chamber 22b- ₁ Thus, the small-diameter master cylinder piston 22a- ₂ is also pushed and moved simultaneously. The first pressure chamber 22b- ₁ and the reservoir 24 are connected via a communication passage 42 having a check valve 41 (or a relief valve).

The pressure detection member 23 penetrates the large-diameter master cylinder piston 22a- ₁ and receives the pressure of the first pressure chamber 22b- ₁ as a reaction force at the tip. The input is directly transmitted from the valve member 40 to the small-diameter master cylinder piston 22a- ₂ when the boosting function is lost via the pressure detection member 23. The first pressure chamber 22b- ₁ is supplemented with brake fluid from the reservoir 24 through the check valve 41.

  Since the other configuration is the same as that of the brake fluid pressure generator of FIG. 1, the same components as those in FIG.

  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 brake fluid pressure generating device of FIG. 1, when not operating, the atmospheric valve 39 is closed and the negative pressure valve 38 is opened as shown in the figure. 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 figure by the input transmitted via the stroke simulator 29, and the valve body 39a follows the valve member 40 to cause the negative pressure valve 38 to move. The communication is closed between the constant pressure chamber 30 and the variable pressure chamber 31. 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 is actuated to generate a hydraulic pressure P1 corresponding to the brake operation amount in the pressure chamber 22b.

  The pressure detection member 23 receives the hydraulic pressure P1 at the tip and applies a reaction force to the valve member 40 of the control valve 37 in the right direction in the figure. The control valve 37 opens the atmospheric valve 39 until the reaction force and the input from the brake pedal 20 are balanced, and closes the atmospheric valve 39 when the input applied to the valve member 40 and the reaction force are balanced.

  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, assuming that the pedal depression force (the depression 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 the equation (1). Become a thing.
L1 = F1 / k1 (1)
Further, the balance formula of the force applied to the power plate 33 is expressed by the equation (2), where the stroke of the power plate 33 is L2, the output of the power plate 33 is F2, and the consumption amount of the brake circuit is M1. It will be.
M1 = (F2 / P1) × L2 (2)
Here, if the cross-sectional area of the master cylinder piston 22a is S22 and the cross-sectional area of the pressure detection 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.

  FIG. 3 shows the relationship between the stroke of the input shaft 28, the pedal effort and the braking effectiveness. In the figure, the solid line shows the characteristics of the brake fluid pressure generator (invention device) of the present invention, and the two-dot chain line shows the conventional pressure-type booster that directly corresponds to the amount of brake pedal operation and the amount of fluid discharged from the master cylinder. This is the characteristic of the brake fluid pressure generator (comparative example).

  As can be seen from this characteristic diagram, the brake fluid pressure generating device of the present invention can ensure the same braking effectiveness with a small amount of operation, and therefore has low drag characteristics aimed at improving vehicle fuel efficiency and reducing brake vibration. The effectiveness is demonstrated also when using a brake caliper or the like.

  As described above, the brake fluid pressure generating device of the present invention can ensure the same braking effectiveness with a small operation amount, and therefore, a brake caliper having a low drag characteristic aimed at improving the fuel efficiency of the vehicle and reducing the brake vibration, etc. Even when used, the effectiveness is demonstrated.

The brake fluid pressure device of FIG. 2 also has a difference that the pressurization of the brake fluid is made between the large-diameter master cylinder piston 22a- ₁ and the small-diameter master cylinder piston 22a- _2. The operation at the time of the fluid amount variation / fluid pressure variation is almost the same as that of the brake fluid pressure generating device of FIG.

−In case of failure of boost function−
When the brake pedal 20 is depressed, as shown in FIG. 4, the stroke simulator 29 moves to the left in the drawing to push the valve member 40, and the valve member 40 hits the valve piston 35 to input. It 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 figure along with the stroke simulator 29 and the control valve 37, and the driver's brake operating force is transmitted via the pressure detection member 23. Directly transmitted to the master cylinder piston 22a. At this time, no negative pressure is introduced into the constant pressure chamber 30, and the power plate 33 remains in the initial position. Therefore, although the assisting force by the negative pressure type booster 21 cannot be obtained, the master cylinder 22 can be directly operated by the driver's braking operation force without receiving the force of the return spring 34, so that the operating force is lost. It is possible to reduce and generate a high brake fluid pressure.

Brake fluid pressure generating device in FIG. 2 When the boosting function fails, the valve piston 35 is pushed in with the power plate 33 left in the initial position, and the input is transmitted to the small-diameter master cylinder piston 22a- ₂ via the pressure detection member 23. The brake fluid pressure generating device of FIG. 2 can pressurize a large amount of fluid because the effective diameter of the master cylinder piston is A during normal operation, and the effective diameter of the master cylinder piston is set to B when the boosting function is lost. Since it decreases, a high fluid pressure can be generated with a small stroke even though the amount of fluid is small.

Sectional drawing which shows the brake hydraulic pressure generator of 1st Embodiment Sectional drawing which shows the brake hydraulic pressure generator of 2nd Embodiment Diagram showing the relationship between input shaft stroke, pedal effort and braking effectiveness Sectional drawing which shows the operating state at the time of the boost function failure of the brake fluid pressure generator of FIG. Sectional drawing which shows an example of the conventional brake fluid pressure generator

Explanation of symbols

20 Brake pedal 21 Negative pressure type booster 22, 220 Master cylinder 22a Master cylinder piston 22a- ₁ Large diameter master cylinder piston 22a- ₂ Small diameter master cylinder piston 22b Pressure chamber 22b- ₁ First pressure chamber 22b- ₂ Second pressure chamber 22c, 22c- ₁ , 22c- ₂ Return spring 23 Pressure detection member 24 Reservoir 25 Brake circuit 26 Brake fluid 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 Transformer 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 Air valve 39a Valve body 39b Valve seats 39c, 39d Spring 40 Valve member 41 Check valve 42 Communication path

Claims (1)

  An input shaft that is operated by a brake operation, a stroke simulator that gives a stroke and a reaction force according to the amount of brake operation to the input shaft, a power piston that amplifies and outputs an input received via the stroke simulator, A control valve that adjusts the output of the power piston in accordance with the amount of operation of the brake operating means, and the input portion including the input shaft, the stroke simulator, and the control valve, and the power piston relatively move in the axial direction. The booster that is enabled, the master cylinder that generates the brake fluid pressure by adding the output of this booster to the master cylinder piston, and the output fluid pressure of this master cylinder is detected to correspond to the detected fluid pressure A pressure detecting member for applying a reaction force to the control valve, and the control valve is connected to the front via the stroke simulator. The input transmitted from the input shaft and the reaction force from the pressure detection member are countered to balance the reaction force against the input, and the input applied to the control valve is passed through the pressure detection member. A brake hydraulic pressure generator configured to be directly transmitted to the master cylinder piston.

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