JP2589622Y2 - Hydraulic brake booster - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The hydraulic brake booster according to the present invention is used in a state of being incorporated in a braking device of an automobile so that a large braking force can be obtained with a small pedaling force.

[0002]

2. Description of the Related Art Various types of brake boosters have been proposed so that when a vehicle is braked, a force for depressing a brake pedal to obtain a required braking force, that is, a pressing force is small. , Is actually used. Among them, a hydraulic brake booster having a structure as shown in FIG. 4 has been known as a hydraulic brake booster for obtaining a larger braking force as compared with a pedaling force by utilizing hydraulic pressure.

[0003] This booster is provided between a rod (which is not shown) built in a master cylinder and a rod which is displaced in the axial direction when a brake pedal is depressed.
Provide in series. On the side of one end (right end in FIG. 4) of the main cylinder 1 whose both ends are closed, a pressure oil supply port 2 communicating with a pressure oil supply source such as a discharge port of a pressure oil pump is provided. An oil discharge port 3 is provided on the side surface at the left end) of each of them.

A piston 4 is provided inside the main cylinder 1.
Are displaceably fitted in the axial direction of the main cylinder 1 (the left-right direction in FIG. 4). The outer peripheral edge of this piston 4 is O
The ring 5 is mounted to maintain oil tightness between the outer peripheral edge and the inner peripheral surface of the main cylinder 1. An oil passage 6 is formed at the center of the piston 4, and one end of the oil passage 6 (FIG.
The right end of the piston 4 is on one side (the right side in FIG. 4) of the piston 4 on the side of the inlet chamber 7 where the pressure oil supply port 2 is present, and the other end (the left end of FIG. 4) is on the other side of the piston 4 (FIG. 4). On the left side of the outlet port 8 on the side of the outlet chamber 8 where the oil discharge port 3 exists.

[0005] An input rod 11 is passed through a through hole 10 formed in the center of the wall 9 on one end side of the main cylinder 1 by a slide bearing 26 so that the axial displacement of the main cylinder 1 can be freely performed. I have. The outer diameter of the input side rod 11 is formed slightly smaller than the inner diameter of the oil passage 6.
The input rod 11 is inserted through the oil passage 6.
The packing 12 mounted on the inner peripheral surface of the through hole 10 is brought into sliding contact with the outer peripheral surface of the input side rod 11 by sliding.
The input-side rod 11 penetrating portion is kept oil-tight. Further, a constricted portion 13 is formed on the outer peripheral surface of the intermediate portion of the input side rod 11, and the constricted portion 13 is formed inside the oil passage 6 with the displacement of the input side rod 11 in the axial direction. When present, the opening area of the oil passage 6 is increased.

An output rod 16 is provided in a through hole 15 formed in the center of a cover plate 14 closing the opening at the other end of the main cylinder 1 so that the main cylinder 1 can be freely displaced in the axial direction. It is inserted. At the base end (right end in FIG. 4) of the output side rod 16, a reaction force is formed by connecting a first large diameter portion 17a on the opening side and a first small diameter portion 17b on the back side by a step 17c. A cylinder 17 is formed, and the reaction force cylinder 17 is formed.
The second large-diameter portion 18a and the second small-diameter portion 18b of the reaction force piston 18 formed at the distal end of the input rod 11 are oil-tightly fitted so as to be freely displaceable in the axial direction. ing.

The second large-diameter portion 18 of the reaction force piston 18 formed at the distal end of the input side rod 11 and fitted to the first large-diameter portion 17a and the first small-diameter portion 17b in an oil-tight manner.
The outer diameter of the second small-diameter portion 18b located on the distal end side between the a and the second small-diameter portion 18b is the same as the outer diameter of the base of the input-side rod 11. Also, the second large diameter portion 18
The outer diameter of the second large-diameter portion 18a
The reaction force chamber 19 is provided between the side surface of the first member 17 and the step 17c. The reaction chamber 19 and the inlet chamber 7 communicate with each other by a hydraulic pressure introduction passage 20 formed inside the input rod 11, and a rear end face of the reaction cylinder 17 is formed with a through hole 21.
Through to the atmosphere. Also, the output side rod 16
The compression spring 22 provided therein presses the input side rod 11 and the output side rod 16 lightly in a direction separating from each other.

The opening edge of the reaction force cylinder 17 is
One side (left side in FIG. 4) of the piston 4 is opposed to the peripheral portion of the oil passage 6, and the piston 4 is displaced to the left in FIG. Displaced to the left. Further, the packing 23 mounted on the inner peripheral surface of the through hole 15 is slidably contacted with the outer peripheral surface of the output rod 16 so as to keep the output rod 16 penetrating oil-tight. The packing 23 and the packing 12 are of a self-sealing type, and the inside of each of the packings 12 and 23 is provided with the entrance chamber 7.
The hydraulic pressure inside has been introduced. Therefore, each of the above packings 1
The inner peripheral edges of the input rod 11 and the output rod 16 have a strength proportional to the oil pressure existing in the inlet chamber 7.
Is pressed against the outer peripheral surface.

Further, a return spring 24 is provided between the inner surface of the cover plate 14 and the piston 4. When the input rod 11 is not pressed leftward in FIG. 4, the piston 4 causes the projection 2 formed on one side (the right side in FIG. 4) of the piston 4 by the elasticity of the return spring 24.
Until 5, 25 abuts against the inner surface of the wall 9, it is displaced to the right in FIG. The operation of the conventional hydraulic brake booster configured as described above is as follows.

From the pressure oil supply port 2 to the inlet chamber 7 of the main cylinder 1
Inside, oil is always being supplied. At the time of non-braking, the constricted portion 13 on the outer peripheral surface of the input rod 11 is located inside the oil passage 6 at the center of the piston 4, so that the oil passes through the oil passage 6 from the inlet chamber 7 to the outlet chamber. 8 and is discharged from the oil drain port 3 to the oil sump. Accordingly, the pressure in the inlet chamber 7 becomes equal to the pressure in the outlet chamber 8, and the piston 4 is not pushed in any direction.

When the brake pedal is depressed to push the input rod 11 to the left in FIG. 4, the constricted portion 13 at the intermediate portion of the input rod 11 comes off the inside of the oil passage 6, and As a result of the opening area of the oil passage 6 being reduced, the pressure in the inlet chamber 7 increases. Therefore, the piston 4
Is pushed to the left in FIG. 4 by the oil pressure in the inlet chamber 7,
The side surface of the piston 4 (the left side surface in FIG. 4) and the opening edge of the reaction force cylinder 17 formed at the base end of the output side rod 16 abut, and the output side rod 16 is pushed by the piston 4. As a result, the output rod 16 is pushed to the left in FIG. 4 with a force greater than the force applied to the input rod 11 as the brake pedal is depressed. Further, the output side rod 16 presses the piston built in the master cylinder with a strong force, and sends out the pressure oil from the master cylinder to the wheel cylinder with a pressure corresponding to the strong force. The hydraulic pressure in the inlet chamber 7 is the reaction chamber 1
9, the input side rod 11 is pressed rightward in FIG. 4 by a force corresponding to the oil pressure in the inlet chamber 7. As a result, a reaction force corresponding to the oil pressure in the entrance chamber 7 is applied to the brake pedal.

[0012]

In the case of the hydraulic brake booster to which the present invention is applied, at the time of braking, the constricted portion 13 is disengaged from the oil passage 6 on the basis of the displacement of the input rod 11 so that the entrance is reduced. The communication between the chamber 7 and the outlet chamber 8 is cut off, and the hydraulic pressure rises in the inlet chamber 7. In order to ensure such a rise in hydraulic pressure, the difference (R−D) between the inner diameter R of the oil passage 6 and the outer diameter D of the input rod 11 is required.
Is preferably as small as possible.

On the other hand, the input rod 11 is supported on the main cylinder 1 via a slide bearing 26, and the piston 4 having the oil passage 6 is provided in the main cylinder 1 with the input rod 11 Are fitted independently. Therefore, the input side rod 1 is taken into consideration while considering the manufacturing error of each part.
In order to reliably prevent the outer peripheral surface of the oil passage 1 from being rubbed against the inner peripheral edge of the oil passage 6, the outer peripheral surface of the input side rod 11 and the inner peripheral edge of the oil passage 6 are reliably damaged. The difference (RD) from the outer diameter D must be increased to some extent.

Thus, the difference between the inner diameter R and the outer diameter D (R
When -D) is increased, a gap having a relatively large area remains between the outer peripheral surface of the input rod 11 and the inner peripheral edge of the oil passage 6 even when the input rod 11 is displaced. . As a result, the hydraulic pressure in the inlet chamber 7 does not rise sufficiently, and the force of pressing the output side rod 16 by the piston 4 becomes weak. Such a phenomenon occurs when driving at low speeds, etc.
This becomes remarkable when the number of revolutions of the engine is low, and thus the amount of pressure oil discharged from the pressure oil pump driven by the engine is small.

In order to solve such a problem, it is sufficient to increase the dimensional accuracy of the constituent members.
The difference (R−D) between the input rod 11 and the oil passage 6 is small even when the error of each part is integrated.
In order to prevent the inner peripheral edge from rubbing against each other, the dimensional accuracy of each of the above-mentioned constituent members must be extremely high, and it is inevitable that the production cost increases. The hydraulic brake booster of the present invention has been devised in view of the above-described circumstances to improve the performance without increasing the manufacturing cost.

[0016]

The hydraulic brake booster according to the present invention has a hydraulic oil supply port at one end and a hydraulic oil supply port at the other end, similarly to the above-mentioned conventional hydraulic brake booster. The main cylinder has an oil discharge port, and the displacement of the main cylinder in the axial direction is performed inside the main cylinder in a state where oil tightness is maintained between the inner peripheral surface of the main cylinder and the outer peripheral edge thereof. A freely fitted piston, one end of which is located on one side of the piston on the inlet chamber side where the pressure oil supply port is present, and the other end is on the other side of the piston on the outlet chamber side where the oil drain port is present, Each of the oil passages that are opened, and a narrow portion that is slightly smaller in diameter than the inside diameter of the oil passage and that has a constricted portion in the middle thereof, makes the wall on one end side of the main cylinder oil-tight, and extends in the axial direction of the main cylinder. Penetrates freely, and penetrates between the constricted portion and the oil passage based on the displacement. An input rod that allows the opening area of the oil passage to be adjustable based on the opposing displacement, and a wall on the other end side of the main cylinder that is oil-tight and penetrates by allowing displacement along the axial direction of the main cylinder. An output rod that allows the piston to freely move to the outlet chamber side, and an output rod formed at the base end of the output rod, and the open end of the output rod is connected to the other surface of the piston by the other surface of the oil passage. A reaction force cylinder opposed to the peripheral portion.

The inner peripheral surface of the reaction cylinder is formed by connecting a first large-diameter portion located on the opening side and a first small-diameter portion located on the back side at a stepped portion. At the distal end of the rod, there is provided a second small-diameter portion that is oil-tightly fitted to the first small-diameter portion and a second large-diameter portion that is oil-tightly fitted to the first large-diameter portion. A force piston is provided. And, with the fitting of the reaction force piston and the reaction force cylinder,
A reaction force chamber is formed between the inner peripheral surface of the first large diameter portion and the outer peripheral surface of the second small diameter portion and communicates with the inlet chamber via a hydraulic pressure introduction path.

In particular, in the hydraulic brake booster of the present invention, the input rod is provided with a base half penetrating the wall of the main cylinder, and a tip provided with the constricted portion and the reaction force piston. The L-shaped hooks formed on the half part and the tip part of the base part and the base part of the tip part are slightly displaced in the direction perpendicular to the axis, but displaced in the axial direction. A connecting portion for connecting the leading half portion and the base half portion so as to freely allow only a slight displacement in a direction perpendicular to the axis by engaging with each other so that the piston is connected to the oil passage. In the portion protruding from the inlet chamber, a guide is provided which is concentric with the oil passage and can be inserted through the first half without play.
The first half is supported at two positions, the guide and the reaction cylinder, so as to be freely displaceable in the axial direction.

[0019]

The operation of the hydraulic brake booster of the present invention configured as described above when displacing the output rod in the axial direction with a force sufficiently larger than the force applied to the input rod is as described above. This is the same as the conventional hydraulic brake booster described above. In particular, in the case of the hydraulic brake booster according to the present invention, of the first half and the base half constituting the input rod,
The first half displaced inside the oil passage formed in the piston,
It is supported by a guide provided on this piston. Therefore, even if the difference between the outer diameter of the first half and the inner diameter of the oil passage is reduced, the outer peripheral surface of the first half and the inner periphery of the oil passage rub against the displacement of the first half. Fear is gone. The operation of connecting the base half and the front half is performed in a state where the gap between the projections and depressions existing in the engagement portion is small or zero in order to minimize the backlash in the axial direction. This can be easily performed by engaging the hooks in the shape of a letter. Therefore, in any state, in order to make the amount of depression of the brake pedal equal to the amount of displacement of the first half portion which affects the magnitude of the braking force, even if the play in the axial direction is small or zero, the assembling is performed. The work is not complicated and the cost is not increased. Accordingly, the difference between the inner diameter of the oil passage and the outer diameter of the first half is made small without particularly complicating the assembling work, and the outer peripheral surface of the first half constituting the input side rod and the oil passage are formed. By avoiding friction with the inner periphery, without increasing the cost,
The performance of the hydraulic brake booster can be improved.

[0020]

1 and 2 show an embodiment of the present invention.
The feature of the hydraulic brake booster of the present invention is that the input side rod is divided into a first half and a base half, and the first half is supported by a guide provided on the piston. It is characterized in that the outer peripheral surface of the first half and the inner peripheral edge of the oil passage formed in the piston are prevented from rubbing each other. Since the configuration and operation of the other parts are the same as those of the above-described conventional hydraulic brake booster, the same parts are denoted by the same reference numerals, and redundant description will be omitted. I will explain this.

FIG. 1 shows that the brake pedal is depressed.
The input rod 11a displaced to the left of the main cylinder 1
Base portion 27 which penetrates through the wall 9 in a liquid-tight manner, a first half portion 28 provided with the constricted portion 13 and the reaction force piston 18, and a connecting portion 29 for connecting the first half portion 28 and the base half portion 27. And The connecting portion 29 is composed of the base half 27 and the first half 28.
The relative displacement in the axial direction (the left-right direction in FIGS. 1 and 2) is not possible, but it is slightly (0.1 mm) in the direction perpendicular to the axis (up and down or front and back in FIGS. 1 and 2). (Slightly smaller units) are possible.

That is, the tip of the base half 27 (FIGS. 1-2)
L-shaped hooks 30 and 31 are formed on the left end of the first half 28 and the base end of the first half 28 (the right end in FIGS. 1 and 2).
0 and 31 are engaged with each other so as to be slightly displaced in the direction perpendicular to the axis but not displaced in the axial direction. A concave groove 35 is formed in the end face of the first half 28 so that the pressure oil present in the inlet chamber 7 can be applied to the center of the tip 28 even when the hooks 30 and 31 are engaged. It can freely enter the provided pressure oil introduction passage 20.

Further, one side of the piston 4 fitted in the main cylinder 1 so as to be freely displaceable only in the axial direction (right side in FIG. 1).
The projections 25a, 25a for limiting the displacement of the piston 4 toward the inlet chamber 7 in a state that the piston 4 protrudes toward the inlet chamber 7 beyond the oil passage 6 formed at the center of the piston 4,
A plurality (for example, three) are formed concentrically with the oil passage 6. A circular guide ring 34 is provided so that the inner peripheral edges of the protrusions 25a, 25a are continuous with each other. The guide ring 34 is concentric with the oil passage 6 and has an inner diameter that allows the first half 28 to be inserted without play.

The first half 28 has its base end (the right end in FIG. 1) inserted through the guide ring 34 so as to be displaceable in the axial direction. The reaction force piston 18 formed at the distal end of the first half 28 is oil-tightly inserted into a reaction force cylinder 17 provided at the base end of the output rod 16. Accordingly, the first half 28 is supported at two positions, the guide ring 34 and the reaction force cylinder 17, so as to be freely displaceable in the axial direction.

The hydraulic brake booster of the present invention having the above-described structure is capable of rotating the output rod 16 with a force sufficiently greater than the force applied in the axial direction of the input rod 11a by depressing the brake pedal. The operation when displacing in the direction is the same as that of the above-described conventional hydraulic brake booster.

In particular, in the case of the hydraulic brake booster according to the present invention, of the first half 28 and the base half 27 constituting the input side rod 11a, displacement occurs inside the oil passage 6 formed in the piston 4. The first half 28 is supported by a guide ring 34 provided on the piston 4. Therefore, even if the difference (R-D ') between the outer diameter D' of the first half 28 and the inner diameter R of the oil passage 6 is reduced, the displacement of the first half 28 causes the displacement of the first half 28. There is no fear that the outer peripheral surface of the oil passage and the inner peripheral edge of the oil passage 6 rub against each other.

Therefore, the inner diameter R of the oil passage 6 and the first half 2
8 (RD-D ') with the outer diameter D' is small, and the outer peripheral surface of the first half 28 of the input rod 11a does not rub against the inner peripheral edge of the oil passage 6. Thus, the performance of the hydraulic brake booster can be improved.

It is difficult to match the center of the oil passage 6 formed in the piston 4 with the center of the base half portion 27 of the input rod 11a, because the manufacturing errors of the components are added up. Is the same as that of the conventional structure, but even when the center of the oil passage 6 is slightly deviated from the center of the base half 27, the coupling portion 29 is displaced and the base half 27 and the first half are displaced. The displacement is absorbed by displacing the portion 28 in a direction perpendicular to the axis.

In addition, the operation of connecting the base half portion 27 and the front half portion 28 to the connecting portion 29 is performed so as to minimize the backlash in the axial direction. It can be easily performed even in a state where the gap between the concave and convex portions existing in the engaging portion is small or zero. That is, the widths (axial dimensions) of the recesses 36, 36 provided at the base ends of the hooks 30, 31 and the protrusions 37, 37 provided at the distal ends of the hooks 30, 31, respectively. Even when the thickness (axial dimension) is matched, after the tip surfaces of the hooks 30 and 31 abut against the mating surface, the base half 27 and the front half 28 are diametrically aligned with each other. By displacing, the L-shaped hook portions 30 and 31 can be easily engaged with each other. Therefore, in any state, the amount of depression of the brake pedal (the amount of displacement of the base half 27)
In order to make the amount of displacement of the first half portion 28 that affects the magnitude of the braking force coincide with the displacement amount of the first half portion 28, even if the rattling in the axial direction existing in the coupling portion 29 is small or zero, the assembly work is complicated. There is no cost increase.

On the other hand, as shown in FIG.
7, a T-shaped engagement convex portion 32 at the distal end, and an engagement groove 33 having a narrow groove-like opening at the base end of the first half portion 28.
In the case of a structure in which the engaging projections 32 and the engaging grooves 33 are engaged with each other, if the rattling in the axial direction existing in the coupling portion 29 is made small or zero, the assembling work is performed. It becomes troublesome. That is, in the case of the structure as shown in FIG. 3, it is difficult to exactly match the axial positions of the engaging projections 32 and the engaging grooves 33. In practice, as shown in FIG. In addition, the assembly operation cannot be performed unless a slight gap extending in the axial direction is interposed in the connecting portion 29. Such a gap,
The play between the base half 27 and the first half 28 causes play between the base half 27 and the first half to be inconsistent when the brake pedal is depressed. This is not preferable because it may deteriorate the operational feeling.

[0031]

[Effect of the Invention] The hydraulic brake booster of the present invention is configured and operates as described above. Therefore, even if machining accuracy is not particularly increased, the outer peripheral surface of the input rod and the oil passage during braking are not required. The area of the gap remaining between the inner peripheral edge and the inner peripheral edge can be reduced. Further, even if the axial play is small or zero, the assembling work does not become troublesome. As a result, a hydraulic brake booster that exhibits stable performance even when the oil flow rate is small, such as when the vehicle is running at low speed, and has an excellent operational feeling can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG. 1 showing a connecting portion between a first half and a base half of the input rod.

FIG. 3 is a view similar to FIG. 2, showing an undesired structure of a connecting portion between a first half and a base half of the input rod.

FIG. 4 is a schematic sectional view showing a conventional hydraulic brake booster.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main cylinder 2 Pressure oil supply port 3 Oil drain port 4 Piston 5 O-ring 6 Oil passage 7 Inlet chamber 8 Outlet chamber 9 Wall 10 Through hole 11, 11a Input side rod 12 Packing 13 Narrow part 14 Cover plate 15 Through hole 16 Output side rod 17 Reaction force cylinder 17a First large diameter portion 17b First small diameter portion 17c Step 18 Reaction force piston 18a Second large diameter portion 18b Second small diameter portion 19 Reaction chamber 20 Hydraulic pressure introducing passage 21 Hole 22 Compression spring 23 Packing 24 Return spring 25, 25a Projection 26 Slide bearing 27 Base half 28 First half 29 Joining part 30, 31, Hook part 32 Engagement convex part 33 Engagement groove 34 Guide ring 35 Depression groove 36 Depression 37 Convex part

Claims (1)

(57) [Scope of request for utility model registration] 1. A main cylinder having a pressure oil supply port at one end and an oil discharge port at the other end, and an inner peripheral surface and an outer peripheral edge of the main cylinder inside the main cylinder. A piston fitted displaceably in the axial direction of the main cylinder in a state where oil tightness is maintained between the piston and one end of the piston is provided on one side of the piston on the side of the inlet chamber where the above-described pressure oil supply port exists. The other end of the piston is provided on the other surface of the piston on the side of the outlet chamber where the oil discharge port is present, and has an oil passage which is opened, and a constricted portion at an intermediate portion having a diameter slightly smaller than the inner diameter of the oil passage. ,
The wall on one end side of the main cylinder is penetrated in an oil-tight manner and freely displaceable in the axial direction of the main cylinder, and the oil passage is performed based on a relative displacement between the constricted portion and the oil passage based on the displacement. An input-side rod whose passage opening area can be adjusted, and a wall on the other end side of the main cylinder that penetrates the wall of the main cylinder in an oil-tight manner and freely displaces in the axial direction of the main cylinder, to an outlet chamber side of the piston. And a reaction force cylinder formed at the base end of the output rod, the opening end of which is opposed to the periphery of the oil passage on the other surface of the piston. The inner peripheral surface of the reaction force cylinder, the first large-diameter portion located on the opening side and the first small-diameter portion located on the back side are continuous in the step portion, the input At the tip of the side rod, a second small diameter that fits oil-tight to the first small diameter And a second large-diameter portion that is oil-tightly fitted to the first large-diameter portion. A reaction piston is provided, and the reaction piston is fitted with the reaction cylinder. A hydraulic brake booster in which a reaction chamber is formed between the inner peripheral surface of the first large-diameter portion and the outer peripheral surface of the second small-diameter portion and communicates with the inlet chamber via a hydraulic pressure introduction passage. In the apparatus, the input rod includes a base half penetrating the wall of the main cylinder, a first half provided with the constricted portion and the reaction force piston, and a front end and a first half of the base half. With the base of the part
The L-shaped hooks formed at the right angles to the axis
Direction but slightly displaced in the axial direction.
A coupling portion that couples the leading half portion and the base half portion so as to freely allow only a slight displacement in a direction perpendicular to the axis by engaging the piston and the piston more than the oil passage. A portion that protrudes into the inlet chamber is provided with a guide that is concentric with the oil passage and that can freely pass through the first half without looseness. The first half includes two portions, the guide and the reaction force cylinder, A hydraulic brake booster characterized by being supported so as to be displaceable in the axial direction.