JPH0241968A - Hydraulic boost apparatus - Google Patents

Abstract

PURPOSE:To obtain good operation feeling by selectively switching the first passage and the second passage having a pressure regulating valve for reducing pressure at a designated pressure reducing ratio, which are disposed parallel to each other, by a selector valve and communicating the main power chamber and the subsidiary power chamber through the selected passage. CONSTITUTION:When the second passage 65b is selected by a selector valve 66, a main power chamber 47 communicates with an orifice 67 through a pressure regulating valve 68. Similarly to the case where the first passage 65a is selected, when liquid pressure is introduced into the chamber 47, a power piston 6 is operated. Further, the liquid pressure introduced in the chamber 47 is introduced through a valve 68 and an orifice 67 into a subsidiary power chamber 50. In this case, the liquid pressure is introduced into the subsidiary power chamber 50 later than the chamber 47 by the orifice 67. Accordingly, when the input is stopped at the intermediate load point, even after the output comes to the value determined depending on the servo ratio of the input, the liquid pressure in the chamber 50 is still increased gradually. The final output is, however, smaller than the output in case of selecting the passage 65a. Thus, the after-effect amount can be changed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic booster used in a brake booster, etc., which performs servo control of input and output at a predetermined servo ratio, and particularly relates to , when the input is stopped in an intermediate load state during servo control, after the output reaches the level obtained by multiplying the input by the servo ratio, the output is further increased by a predetermined amount, so-called. The present invention relates to a hydraulic booster having aftereffect characteristics.

(Prior Art) In general, a hydraulic booster includes a power piston that is slidably fitted into a housing, a power chamber into which hydraulic pressure acting on one end of the power piston is introduced, and a hydraulic booster that is connected to the power chamber. The power supply includes a control valve that switches and controls communication with a source or a reservoir, an input shaft that operates the control valve, and an output shaft that is connected to a power piston. By operating the input shaft and switching the control valve, hydraulic pressure from a hydraulic pressure source is introduced into the power chamber, and the hydraulic pressure operates the power piston to output from the output shaft.

In that case, the hydraulic booster performs so-called servo control, which controls the magnitude of the output of the output shaft in response to the magnitude of the input of the input shaft.In other words, the output is the magnitude of the input boosted by the servo ratio. It's sato.

Such hydraulic pressure boosters are used, for example, in brake boosters in automobile braking systems, and by obtaining a large braking force with a small brake pedal depression force,
This ensures reliable braking and reduces driver fatigue.

By the way, in a car braking system using such a brake booster, when the brake pedal is depressed for a certain amount and then stopped in that state,
The output of the brake booster increases to a level where the input is boosted by the servo ratio, and thereafter the output remains constant. Therefore, the braking force also increases and then remains constant. Looking at this in terms of vehicle deceleration, as shown in Figure 3 (B), after the loss due to input shaft sliding resistance, valve resistance, etc. is absorbed by braking, the vehicle deceleration decreases. The velocity increases along the straight line δ1 from point e. When the amount of depression of the brake pedal is held constant at the intermediate load point, the deceleration of the vehicle becomes constant from point f and follows a straight line δ. At this time, the deceleration of the vehicle changes greatly from straight line δ to straight line δ6, so the vehicle begins to receive a shock. When this impact is received, it gives the driver an unpleasant feeling and makes it impossible for the driver to drive comfortably.Therefore, the braking system is designed to reduce this impact as much as possible to maintain good brake performance. You are required to make sure that you get the ring.

For this reason, Japanese Utility Model Application Laid-Open No. 61-64074 discloses a brake booster that prevents a sudden change in deceleration when the deceleration of a vehicle changes from increasing to constant.

This brake booster is a negative pressure type, but when the input is stopped at an intermediate load point, the output increases and reaches the level determined by the servo ratio, and then only the output is increased to a predetermined level.
The output is increased gradually and then kept constant. In other words, an aftereffect effect on the brake is performed. Due to this aftereffect, the deceleration of the vehicle does not increase and become constant all at once, but becomes constant after passing through a region where the deceleration gradually increases. That is, in FIG. 3(B), the deceleration is a straight line δ3. δ2, and δ.

According to such a brake booster, the deceleration does not change significantly, so that the impact applied to the vehicle can be alleviated.

(Problem to be Solved by the Invention) However, in such a brake booster, the amount of gradual increase in output, that is, the amount of aftereffect always remains constant. For this reason, the amount α of gradual increase in deceleration is always a constant value,
This gradual increase amount α cannot be changed depending on various conditions such as road conditions and driving conditions. As a result, better brake feeling cannot be obtained.

Therefore, it is desirable to be able to change the amount of aftereffect of such a brake booster depending on various conditions.

The present invention has been made in view of the above circumstances, and its purpose is to change the amount of aftereffect of the output according to various conditions to obtain a better operating feeling. An object of the present invention is to provide a pressure booster.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a power piston with a first piston part and a second piston part, and the first piston part is introduced into the main power chamber. The hydraulic pressure introduced into the auxiliary power chamber communicating with the main power chamber via the orifice is applied to the second piston portion.

A switching valve is connected to the main power chamber, and a first passage and a second passage provided with a pressure regulating valve that reduce pressure at a predetermined pressure reduction ratio are connected to the switching valve, respectively. The first passage and the second passage are connected to the upstream side of the orifice, and the first and second passages are selectively switched by the switching valve.

(Function) In the hydraulic pressure booster according to the present invention having such a configuration, the first passage side is selected, for example, by the switching valve. When hydraulic pressure is introduced into the main power chamber, the hydraulic pressure acts on the first piston portion, and the power piston operates. Further, hydraulic pressure introduced into the main power chamber is introduced into the auxiliary power chamber through selected first passages and orifices. In that case, the orifice introduces hydraulic pressure into the auxiliary power chamber later than the hydraulic pressure in the main power chamber. Therefore, when the input stops at an intermediate load point, even after the output reaches a level determined by the servo ratio relative to the input, the hydraulic pressure in the auxiliary power chamber gradually increases with a delay. Then, since this hydraulic pressure acts on the second piston portion, the output is further gradually increased by a predetermined amount. Thereafter, when the hydraulic pressure in the auxiliary power chamber becomes constant, the output becomes constant.

When the second passage side is selected by the switching valve, the main power chamber comes to communicate with the orifice via the pressure regulating valve. 1st
As in the case where the passage side is selected, when hydraulic pressure is introduced into the main power chamber, the power piston operates. Furthermore, the hydraulic pressure introduced into the main power chamber is introduced into the auxiliary power chamber through the pressure regulating valve and orifice of the second passage. In that case, the orifice introduces hydraulic pressure into the auxiliary power chamber later than the hydraulic pressure in the main power chamber. Therefore, when the input stops at an intermediate load point, even after the output reaches a level determined by the servo ratio of the input, the hydraulic pressure in the auxiliary power chamber continues to gradually rise. Then, since this hydraulic pressure acts on the second piston portion, the output is further gradually increased by a predetermined amount. Thereafter, when the hydraulic pressure in the auxiliary power chamber becomes constant, the output becomes constant.

In that case, the hydraulic pressure in the auxiliary power chamber is the same as the hydraulic pressure in the main power chamber reduced by the pressure regulating valve, so the final output will be smaller than the output when the first passage side is selected. Become.

That is, the amount of aftereffect of the output is smaller than when the first passage side is selected.

In this way, it becomes possible to change the aftereffect amount of the output of the hydraulic pressure booster which performs an aftereffect effect when the input stops at an intermediate load point.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of a hydraulic pressure booster according to the present invention applied as a brake booster, and FIG. 2 is a longitudinal sectional view of a pressure regulating valve used in this embodiment. be.

As shown in FIG. 1, the brake booster 1 includes a housing 2 that is substantially cylindrical. The housing 2 has a first hole 3 and a second hole 4 which are opened at the right end and left end of the housing 2, respectively, and these first and second holes.
Third holes 5 communicating with the second holes 3.4 are coaxially bored. The diameter of the second hole 4 is set larger than the diameter of the third hole 5.

A power piston 6 is disposed across the second and third holes 4 and 5. This power piston 6 has a first piston part 8 that slides fluid-tightly in the third hole 5 with a seal 7, and a larger one than the first piston part 8 that slides fluid-tightly in the second hole 4 with a seal 9. A second piston portion lO having a diameter. The power piston 6 also has fourth and fifth holes 11.12 that open at the left and right ends, respectively, and these holes 11.12.
A sixth hole 13 communicating with each other is formed coaxially with each other.

A plug 14 is fixed to the right end of the housing 2 with a nut 15. This plug 14 closes the first hole 3 in a fluid-tight manner. Further, the middle portion of the plug 14 is fitted into the third hole 5 in a fluid-tight manner, and the left end portion of the plug 14 is inserted into the fourth hole 11 of the power piston 6. A gap of a predetermined size is formed between the power piston 6 and the left end of the plug 14.

In the plug 14, the seventh hole 16 is connected to the fourth to sixth holes 11 to 13.
It is drilled coaxially with the An input shaft 17 is slidably inserted into the seventh hole 16. A pair of seals 1 are provided between the plug 14 and the input shaft 17 at both ends of the plug 14.
8.18, it is liquid-tight.

A flange portion 19 is formed at the left end of the input shaft 17, and when the input shaft 17 moves to the right, this flange portion 1
9 comes into contact with a ring-shaped retaining member 20 provided on the power piston 6, thereby preventing the input shaft 17 from coming out from the power piston 6. Further, the flange portion 19 includes a step portion 21 between the fourth hole 11 and the sixth hole 13.
It is possible to move relative to the power piston 6 between the and the retaining member 20. Furthermore, a cylindrical member 22 is provided at the left end of the input shaft 17.

On the other hand, the right end of the input shaft 17 is connected to a brake pedal (not shown) via a connecting member 23. A retractable boot 24 is provided between the right end of the housing 2 and the connecting member 23, and the right end opening of the housing 2 is covered by the boot 24.

An axial passage 26 communicating with the hole 25 of the cylindrical member 22 is bored at approximately the center of the input shaft 17, and a diametric passage 27 communicating with the right end of this passage 26 is bored. . This passage 27 communicates with an annular groove 28 formed in the plug 14, which is connected to an annular chamber 30 between the housing 2 and the plug 14 via a diametric passage 29 bored in the plug I4. is connected to. Furthermore.

The annular chamber 30 communicates with a reservoir 33 via an outlet 31 and an outlet conduit 32 formed in the housing 2 .

A valve body 35 having a ball 34 at the right end is slidably disposed in the sixth hole 13 of the power piston 6. Also, the 6th
A cylindrical valve seat member 36 is fixed at the right end of the hole 13, and the ball 34 of the valve body 35 is seated on this valve seat member 36 by the biasing force of a compression coil spring 37. Further, the left end portion of the cylindrical member 22 faces the ball 34 within the hole 38 of the valve seat member 36 .

A compression coil spring 39 is disposed between the cylindrical member 22 and the valve seat member 36. This spring 39 constantly biases the input shaft 17 and the cylindrical member 22 in the direction in which the cylindrical member 22 moves away from the valve body 35, that is, in the right direction, and the force on the input shaft 17 is strong enough to overcome the biasing force of the spring 39. When a leftward force of the magnitude of is not applied, the right end surface of the flange portion 19 of the human power shaft 17 is brought into contact with the retaining member 20. The distance between the ball 34 and the left end of the cylindrical member 22 when the right end surface of the flange portion 19 is in contact with the retaining member 20 is the distance between the left end surface of the flange portion 19 and the stepped portion 21 at that time. It is set shorter than the distance. As a result, when the input shaft 17 moves to the left with respect to the power piston 6, the left end of the cylindrical member 22 contacts the ball 34, moves the valve body 35 to the left, and moves the ball 34 to the valve seat member 36. It is now possible to make people leave their seats. When the left end of the cylindrical member 22 comes into contact with the ball 34, the hole 25 of the cylindrical member 22 is closed.

That is, the cylindrical member 22, the valve body 35 including the ball 34,
i5 and the valve seat member 36 constitute a control valve 40.

An annular spacer 4 is provided in the fifth hole 12 of the power piston 6.
The right end of the output shaft 42 is fluid-tightly fitted through the power piston 1, and the right end cannot be moved axially relative to the power piston 6 by a ring-shaped retaining member 43 attached to the power piston 6. It is said that This output shaft 42 is adapted to operate a piston of a brake mask cylinder (not shown) fixed to the left end of the housing 2. A plug 44 that substantially closes the second hole 4 is screwed into the housing 2, and a compression coil spring 46 disposed between the plug 44 and a stepped portion 45 formed at the right end of the output shaft 42 , the output shaft 42 and the power piston 6 are always biased to the right. Spring 46 to power piston 6
When a force large enough to the left is not applied to overcome the urging force of ing.

The main power chamber 4 is located between the power piston 6 and the plug 14.
7 is formed, and a chamber 48 is formed between the power piston 6 and the output shaft 42 by a spacer 41.

These compartments 47 , 48 communicate with each other by passages 49 formed in the power piston 6 . Further room 48
The left end of the valve body 35 faces inside. On the other hand, between the housing 2 of the second hole 4 and the power piston 6,
A sub-power chamber 50 is formed.

An annular groove 52 is provided on the outer periphery of the power piston 6 between a seal 51 and a seal 7 provided on the power piston 6, and this groove 52 is connected to the ball through a passage 53 formed in the power piston 6. 34 and the valve seat member 36, and a pressure chamber 55 defined by a seal member 54 that seals the valve body 35. Further, the hole 52 communicates with the supply port 58 via a hole 56 formed in the housing 2 and a filter 57 . This supply 058 communicates via a supply conduit 59 with the accumulator 60 and the discharge side of the pump 61, the suction side of the pump 61 with the reservoir 33.
is connected to. Pump 61 and accumulator 60 constitute the hydraulic pressure source of the present invention. Between the accumulator 60 and the pump 61, there is a connection between the pump 61 and the accumulator 60.
A check valve 62 is interposed to allow liquid to flow in the direction toward, but to prevent liquid from flowing in the opposite direction.

Furthermore, the housing 2 includes a first
A connecting rod 63 and a second connecting rod 64 communicating with the auxiliary power chamber 50 are provided, respectively. The first connection hole 63 is a conduit 65
The first boat 66a of the 3-bot 2-position switching valve 66
It is connected to the.

A second boat 66b of the switching valve 66 is connected to the upstream side of the orifice 67 via a conduit 65a.

Conduit 65 and conduit 65a constitute the first passage of the present invention.

Further, the third port 66C of the switching valve 66 is connected to the input port 69 of the pressure regulating valve 68 via a conduit 65b. Second
As shown in the figure, the pressure regulating valve 68 includes a pressure reducing piston 72 slidably disposed within a stepped hole 71 of a housing 70. This decompression piston 72 has an upper end 73 and a lower end 74 with small diameters, and an intermediate part 75.
is considered to have a large diameter. The upper end 73 of the decompression piston 72 is slidably fitted into a hole 77 of a plug 76 that closes the stepped hole 71 of the housing 70, and a seal 78
It is said to be liquid-tight. Further, the intermediate portion 75 is slidably inserted into the intermediate diameter portion of the hole 71.
Several grooves 79 in the axial direction are formed on the outer circumference. Further, a rubber cup seal 80 is provided at the stepped portion between the intermediate diameter portion and the small diameter portion of the hole 71, and the hole 81 of the rubber cup seal 80 is connected to the lower end portion of the decompression piston 72.
4 and the intermediate portion 75 is penetrated. The lower end 74 of the pressure reducing piston 72 is slidably inserted into the small diameter portion of the hole 71, and several axial grooves 82 are formed on the outer periphery of the lower end 74. In the housing 70, an input chamber 83 is formed between the seal 78 and the intermediate portion 75 of the pressure reducing piston 72, and an output chamber 84 is formed between the lower end 74 of the pressure reducing piston 72 and the housing 70. ing. The pressure reducing piston 72 is always urged downward by a compression coil spring 85, and the lower end of the pressure reducing piston 72 normally comes into contact with the bottom of the hole 71.

The biasing force of this spring 85 is set to be relatively small, and the difference between the upward force due to the pressure of the output chamber 84 applied to the decompression piston 72 and the downward force due to the pressure of the input chamber 83 is relatively early. Furthermore, the decompression piston 72 is able to move upward against the biasing force of the spring 84. When the decompression piston 72 moves upward, the lower end 74 contacts the rubber cup seal 80 to close the hole 81. When the hole 81 is closed, the communication between the input chamber 83 and the output chamber 84 is cut off, so that the pressure in the output chamber 84 is equal to the effective pressure receiving area on the output chamber side of the pressure reducing piston 72 relative to the pressure in the input chamber 83. The pressure is reduced at a pressure reduction ratio determined by the ratio to the effective pressure receiving area on the chamber 83 side. The input chamber 83 communicates with the input port 69, and the output chamber 84 communicates with an output 086 formed in the housing 70. An output 086 of the pressure regulating valve 68 is connected to the upstream side of the orifice 67 via a conduit 65b. The conduit 65 and the conduit 65b constitute the second passage of the present invention.

Therefore, in the illustrated first position ■ of the switching valve 66,
The first connecting hole 63 is directly connected to the orifice 67,
When the switching valve 66 is switched to the second position TI, the first connecting hole 63 is connected to the orifice 67 via the pressure regulating valve 68.

The downstream side of the orifice 67 is connected to a second connecting hole 64 .

A check valve 87 is arranged in parallel with the orifice 67.

This check valve 87 allows liquid to flow from the second connecting hole 64 to the first connecting hole 63, but prevents the liquid from flowing in the opposite direction. Further, a hydraulic pressure absorbing device 88 is provided between the orifice 67 and the second connecting hole 64. Further, the second connecting hole 64 is connected to the reservoir 33 via a check valve 89. The check valve 89 allows the liquid to flow from the reservoir 33 to the second connecting hole 64, but prevents the liquid from flowing in the opposite direction.

Next, the operation of this embodiment will be explained.

The pump 61 is driven and the hydraulic fluid is introduced from the reservoir 33 into the accumulator 60 via the check valve 62, and the supply conduit 59, the supply 058, the filter 57, and the passage 56
, and is introduced into the pressure chamber 55 via the passage 53. A constant level of hydraulic pressure is maintained in the pressure chamber 55 and the accumulator 60 at all times.

First, the switching valve 66 is set to the first position (3).

Therefore, the first connecting hole 63 is directly connected to the orifice 67.

When the brake is not applied, the brake booster l is in the state shown in FIG.

That is, the input shaft 17, the power piston 6, and the output shaft 42 are all located at the oldest position. In this state, the ball 34 of the control valve 40 is seated on the valve seat member 36, and the cylindrical member 22 is separated from the ball 34. Therefore, the main power chamber 47 is cut off from the pressure chamber 55, and the hole 25
, the passage 26, the passage 27, the annular groove 28, the passage 29, the annular chamber 30, the outlet 3m and the outlet conduit 32 to the reservoir 3.
It is connected to 3. Therefore, the hydraulic pressure within the main power chamber 47 is approximately zero.

When a brake pedal (not shown) is depressed for braking, the input shaft 17 moves to the left, and the tip of the cylindrical member 22 comes into contact with the ball 34 . Therefore, the hole 25 of the cylindrical member 22 is closed, and the communication between the main power chamber 47 and the reservoir 33 is cut off. During this period, as shown in FIG. 3(A), up to point a, even if the input to the input shaft 17 increases, there is no output from the output shaft 42.

Furthermore, when the input shaft 17 moves to the left, the ball 34 separates from the valve seat member 36 and the pressure fluid in the pressure chamber 55 flows into the main power chamber 47.
be introduced within. This pressure fluid causes the power piston 6 to move to the left against the elastic force of the spring 46, so that the output shaft 42 outputs an output to operate the piston of the mask cylinder.

Braking is thereby performed. At this time, as the second piston part 10 moves, the inside of the auxiliary power chamber 50 tends to become negative pressure, but since the hydraulic fluid at atmospheric pressure is sucked from the reservoir 33 via the check valve 89, Sub-power room 50
There is no negative pressure inside.

Therefore, the power piston 6 can move smoothly without resistance. In addition, since the hydraulic pressure in the main power chamber 47 also acts on the input shaft I7, this hydraulic pressure causes the input shaft 17 to
The force applied to the brake is transmitted to the driver as a brake reaction force. As the power piston 6 moves, the valve seat member 36 also moves to the left, and when the valve seat member 36 comes into contact with the ball 34, communication between the pressure chamber 55 and the main power chamber 47 is cut off. Therefore, no more pressure fluid is introduced into the main power chamber 47, and the movement of the power piston 6 is stopped. As a result, pressurized fluid is introduced into the main power chamber 47 in an amount corresponding to the amount of depression of the brake pedal, ie, the amount of human power on the input shaft 17. Therefore, the output of the output shaft 42 has a magnitude corresponding to the input of the input shaft 17, that is, a magnitude obtained by multiplying the input by the servo ratio, and as shown in FIG. 3(A), the hydraulic pressure is boosted. The device 1 comes to operate along the straight line γ1 from point a. The hydraulic booster l operates along this straight line γ until the hydraulic pressure in the main power chamber 47 rises to the full load point C, which is the set maximum pressure. When the full load point C is exceeded, the pressure in the main power chamber 47 no longer rises, so the amount of increase in output is almost the same as the amount of increase in input, and the brake booster 1 follows the straight line γ2 with an approximately 45 degree inclination. It will work accordingly.

Further, the pressure liquid in the main power chamber 47 passes through the passage 49 to the chamber 48.
It will also be introduced inside. Since the hydraulic pressure in this chamber 48 comes to act on the left end of the valve body 35, the force applied to the valve body 35 due to the hydraulic pressure in the main power chamber 47 is reduced, causing it to move to the left. There is no need to increase the elastic force of the spring 37 so much.

By the way, the hydraulic pressure in the main power chamber 47 is transmitted from the first connecting hole 63 to the conduit 65. It is also introduced into the auxiliary power chamber 5° via the switching valve 66, the orifice 67, and the second connecting hole 64. At this time, the pressure liquid that has passed through the orifice 67 also tries to flow toward the reservoir 33 , but the check valve 89 prevents the pressure liquid from flowing into the reservoir 33 . As a result, the pressure fluid is introduced only into the auxiliary power chamber 50. The pressure in the auxiliary power chamber 50 increases later than the pressure in the main power chamber 47 because the pressure fluid is throttled by the orifice 67 and a predetermined amount of pressure is absorbed by the hydraulic pressure absorption device 88. Become. Therefore, for example, when the input from the input shaft 17 is stopped at the intermediate load point and the valve seat member 36 comes into contact with the ball 34, the pressure within the main power chamber 47 will no longer rise.

However, since the pressure in the auxiliary power chamber 50 increases with a delay, even if the input to the input shaft 17 stops, the output of the output shaft 42 further increases, and the brake booster l increases as shown in FIG. 3(A).
It comes to operate along the straight line γ from point to point d. As a result, even after the brake pedal is stopped at a desired point, the braking force is gradually increased by a predetermined amount.

That is, an aftereffect effect of the brake is performed.

This aftereffect effect of the brake can be explained in terms of the relationship between the brake operation time and vehicle deceleration, as shown in FIG. 3(B).Vehicle deceleration occurs at the 0 point,
increases along the straight line δ. At an intermediate load point where the human power on the input shaft 17 stops, the vehicle deceleration increases to point f. Even if the input stops, the output increases from point b to point d, so the vehicle deceleration is not constant, but after point 0g, it gradually increases along the straight line δ2 up to point g. Since the pressure within the auxiliary power chamber 50 does not increase, the output of the brake booster l remains constant and the vehicle deceleration remains constant.

When the brake pedal is released to release the brake operation, the input shaft 17 moves to the right. For this reason,
The left end of the cylindrical member 22 separates from the ball 34, the main power chamber 47 communicates with the reservoir 33, and its pressure decreases. spring 46
The power piston 6 moves to the right due to the elastic force of , and as a result, the pressure fluid in the main power chamber 47 is discharged to the reservoir 33, and the pressure fluid in the auxiliary power chamber 50 is also discharged from the check valve 87.
, the switching valve 66 , and the main power chamber 47 before being discharged into the reservoir 33 . At this time, the pressure fluid in the auxiliary power chamber 50 mainly flows through the check valve 87 and is not affected by the orifice 67, so the power piston 6 moves to the right without delay and its right end It returns to its original position where it contacts the plug 14. That is, as shown in FIG. 3(A), the output of the brake booster l operates along the straight line γ4.

Next, when the switching valve 66 is switched to the second position II side, the first connecting hole 63 is connected to the orifice 67 via the pressure regulating valve 68.
connected to.

The above-mentioned switching valve 66 is used as the first
Since this is the same as when it is set in device I, its explanation will be omitted.

When a brake operation is performed and pressure fluid is introduced into the main power chamber 47, the pressure fluid flows through the pressure regulating valve 68 and the orifice 6.
7 and is also introduced into the sub-power chamber 50. In that case, the pressure increase in the auxiliary power chamber 50 is delayed by the orifice 67 than the pressure increase in the main power chamber 47 .

When the input to the input shaft 17 is stopped at an intermediate load point,
The output of the output shaft 42 increases along the straight line γ. In that case, if there is a difference between the force due to the pressure of the output chamber 84 and the force due to the pressure of the input chamber 83 applied to the decompression piston 72 to the extent that it overcomes the elastic force of the spring 85, the decompression piston 72
2 rises against the elastic force of the spring 85. As the vacuum piston 72 rises, the lower end 74 closes to the rubber cup seal 80.
and closes the hole 81 of the seal. therefore,
After this, the fluid pressure in the main power chamber 47 is reduced at a pressure reduction ratio determined by the ratio of the effective pressure receiving area on the output chamber 84 side of the pressure reducing piston 72 to the effective pressure receiving area on the input chamber 83 side, and the fluid pressure in the auxiliary power chamber 50 is reduced. can be conveyed to. Therefore, the maximum pressure introduced into the auxiliary power chamber 50 is smaller than the maximum pressure when the switching valve 66 is in the first device I. That is, the output of the output shaft 42 stops at a point d' which is smaller than the point d when the switching valve 66 is at the first position ff1I.

To explain this with reference to FIG. 3(B), due to the aftereffect of the brake, the vehicle deceleration increases from point f to point g', but it increases up to point g when the switching valve 66 is in the first device I. After that, the deceleration becomes constant and follows the straight line δ4. In this way, the pressure regulating valve 68 changes the final vehicle deceleration. That is, the amount α of gradual increase in deceleration changes to α' depending on the pressure reduction ratio of the pressure regulating valve 68. Therefore, by appropriately setting the pressure reduction ratio of the pressure regulating valve 68, it becomes possible to obtain a desired gradual increase amount α in vehicle deceleration.

When the brake is released, the output of the brake booster l decreases along the straight line γ56. In the above embodiment, only one second passage provided with the pressure regulating valve 68 is provided. However, the present invention is not limited to this, but it is possible to provide a plurality of second passages in parallel each having pressure regulating valves 68 having different pressure reduction ratios, and to replace these pressure regulating valves 68 with an appropriate number of switching valves. By switching, it is also possible to set the amount α of gradual increase in deceleration of various magnitudes. If you do it like this.

For example, by appropriately selecting these pressure regulating valves depending on road conditions, driving conditions, etc., it is possible to further improve the brake feeling. In that case, the gradual increase amount α can be automatically selected by using a solenoid valve as the switching valve and combining this solenoid valve with various sensors.

Furthermore, the orifice 67 can also be a variable aperture that can change the aperture. In this way, the aftereffect ratio of deceleration in the brake aftereffect effect, that is, the angle θ shown in FIG. 3 can be changed as appropriate.

(Effects of the Invention) As is clear from the above description, the hydraulic booster according to the present invention includes a power piston provided with a first piston part and a second piston part, and a main power chamber connected to the first piston part. Since the introduced hydraulic pressure is applied to the second piston portion and the hydraulic pressure introduced to the auxiliary power chamber communicating with the main power chamber via the orifice is applied, at the intermediate load point, When the input is stopped, the output reaches a level determined by the servo ratio, and then gradually increases by a predetermined amount.

Therefore, the hydraulic booster can reliably perform an aftereffect effect on the output.

For example, if this hydraulic pressure booster is used as a brake booster, it will be possible to reliably provide an aftereffect effect on the brakes, effectively mitigating the impact applied to the vehicle during braking. be able to.

In addition, the switching valve selectively switches between the first passage, which is arranged in parallel with each other, and the second passage, which is equipped with a pressure regulating valve that reduces pressure at a predetermined pressure reduction ratio. Since the auxiliary power chamber and the auxiliary power chamber are communicated with each other, the pressure introduced into the auxiliary power chamber can be varied. Therefore, it is possible to vary the amount α of gradual increase in output.

By switching and controlling the switching valve according to various conditions, the operating feeling of the hydraulic pressure booster can be finely tuned and improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment in which the hydraulic pressure booster according to the present invention is applied to a brake booster, FIG. 2 is a longitudinal sectional view of a pressure regulating valve used in this embodiment, and FIG. 3 (A),
(B) is a characteristic diagram showing the characteristics of this embodiment and the conventional brake booster. 66...Switching valve, valve regulator 67...Orifice, 68...Kenji Aoki Pressure Control Automotive Equipment Co., Ltd.

Claims (1)

[Claims] a power piston that is slidably fitted into a hole in the housing and includes a first piston portion and a second piston portion; a main power chamber into which hydraulic pressure acting on the first piston portion is introduced;
an auxiliary power chamber that communicates with the main power chamber via an orifice and into which hydraulic pressure acting on the second piston is introduced; a hydraulic pressure source that generates the hydraulic pressure; An input shaft inserted into the input shaft, an output shaft connected to the power piston, and when the input shaft is inactive, communication between the hydraulic pressure source and the main power chamber is cut off, and communication between the main power chamber and the reservoir is disconnected. a control valve that communicates with the main power chamber and operates when the input shaft moves toward the power piston to cut off communication between the main power chamber and the reservoir and communicate the hydraulic pressure source with the main power chamber. and a first passage arranged in parallel between the orifice and the main power chamber so as to connect them, and a second passage provided with a pressure regulating valve that reduces the pressure at a predetermined pressure reduction ratio; A hydraulic booster comprising: a switching valve that selectively switches between first and second passages of the hydraulic power chamber and connects the main power chamber and the orifice through the selected passage.