JPH09142271A - Brake valve for total hydraulic power brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized total hydraulic power brake device while securing auxiliary braking force for keeping a vehicle stopped during working. SOLUTION: A pressing rod 13 is lowered by actuating a brake pedal. A pilot piston 31 having a bottomed cylindrical main part 32 is oiltightly and externally engaged with a small-diameter part 34 formed at the lower end part of the pressing rod 13. In keeping a vehicle stopped during working, pressure oil is fed into a pilot cylinder 15a in the main part 32 from a pilot port 27. As a result, a transmission spring 19 is downwardly displaced without lowering the pressing rod 13 to switch a spool 6 for braking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The brake valve for an all-hydraulic power brake device according to the present invention is provided for applying a large braking force to each wheel during work of a truck or various construction vehicles, or on the passenger side. Used to apply braking force to the wheels by depressing the brake pedal.

[0002]

2. Description of the Related Art In addition to a normal parking brake that applies braking force only to some wheels, such as trucks and various construction vehicles, in order to prevent the vehicles from inadvertently moving during work, An auxiliary braking device that applies a braking force to a wheel may be provided. In such an auxiliary braking device, a brake cylinder (wheel cylinder) attached to each wheel is added with a hydraulic pressure slightly lower than the maximum hydraulic pressure at the time of regular braking for stopping the traveling vehicle, and It is required to have the function of maintaining the hydraulic pressure even if the brake pedal is not depressed.

For this reason, conventionally, for example, the actual Kaihei 4-435.
As described in JP-A-60, not only when the driver depresses the brake pedal, but also when the driver does not depress the brake pedal during work, a predetermined hydraulic pressure can be supplied to the wheel cylinder. Brake valves for hydraulic power brake devices are known. 2 to 3 show an example of a conventionally known brake valve for an all-hydraulic power brake device. The valve case 1 is configured by connecting an upper case 2, a lower case 3, and a bottom cover 4, each of which is formed in a vertical cylindrical shape, in series in the vertical direction in an oil-tight manner.

A primary spool 6 and a secondary spool 7 are vertically arranged in a first cylinder portion 5 provided inside the lower half of the lower case 3, which is the inside of one half of the valve case. They are provided in series so as to be vertically movable (displaced in the axial direction) in the first cylinder portion 5. These primary spool 6 and secondary spool 7 are the spools described in the claims. Among these, a return spring 26, which is a compression coil spring, is provided between the locking plate 25 locked to the lower end of the secondary spool 7 and the upper surface of the bottom cover 4, and is placed above both spools 6 and 7. The elastic force is applied to (the other end of the valve case is pressed). A mounting substrate 8 is fixed to the outer periphery of the upper end of the valve case 1 with bolts 9. Then, the horizontal axis 1 provided on the upper surface of the mounting substrate 8
0, the base end portion (right end portion in FIG. 2) of the brake pedal 11 is swingably supported. This brake pedal 1
A roller 12 is pivotally supported at an intermediate portion of the lower surface of 1, and a part of the outer peripheral surface of the roller 12 is brought into contact with the upper surface of the pressing rod 13. The pressing rod 13 is vertically (displaceable in the axial direction) freely and oil-tightly inside the second cylinder portion 14 formed in the central portion of the upper case 2, which is inside the other half of the valve case. It is inserted.

Further, the lower half portion (the other end side portion) of the pressing rod 13 is formed in a bottomed cylindrical shape having an opening at the bottom to form a pilot cylinder 15, and this pilot cylinder 1
A cylindrical pilot piston 16 is fitted inside 5 in an oil-tight manner. A pilot port 27 is provided on the side surface of the upper case 2, and the pilot port 27 and the upper end of the pilot cylinder 15 can communicate with each other regardless of whether the pressing rod 13 is lifted or lowered. An upper locking plate 17 is attached to the lower end of the pilot piston 16.
The lower engagement plate 18 is engaged with the upper end portion of the primary spool 6, and a transmission spring 19 which is a compression coil spring is provided between the engagement plates 17 and 18. The elastic force of the transmission spring 19 is sufficiently larger than the elastic force of the return spring 26. Further, a return spring 21 is provided between the lower surface of the locking plate 20 locked to the lower end of the pressing rod 13 and the inner surface of the intermediate portion of the lower case 3 so that the pressing rod 13 is provided with an elastic force directed upward. Granted.

On the other hand, at two upper and lower positions on one side surface (left side surface in FIG. 2) of the lower case 3, receiving ports communicating with independent brake accumulators (not shown), which are pressure oil sources, respectively. 22a and 22b are formed, respectively. Discharge ports 23a and 23b communicating with independent brake cylinders (wheel cylinders), which are not shown, are formed at two upper and lower positions on the other side surface (the right side surface in FIG. 2) of the lower case 3, respectively. The vertical positional relationship between the receiving port 22a provided on the upper side and the discharge port 23a, and the receiving port 22b provided on the lower side
The vertical positional relationship between the discharge port 23b and the discharge port 23b is slightly shifted. In addition, a small-diameter portion 24 is provided in each of the intermediate portions of the primary spool 6 and the secondary spool 7.
a and 24b are formed. Therefore, when the primary spool 6 and the secondary spool 7 are lowered against the resilience of the return spring 26 (displacement to one end side of the valve case), the receiving ports 22a and 22b and the discharge ports 23a and 23b are displaced. Only in the case of), they communicate with each other via the small diameter portions 24a and 24b. When the spools 6 and 7 are fully raised by the elastic force of the return spring 26, the discharge ports 23a and 23b are discharged.
And a return port (not shown), which is opened at a position higher than the discharge ports 23a and 23b, communicates with each other through the small diameter portions 24a and 24b. Therefore, when the spools 6 and 7 are fully raised, the hydraulic pressure existing in the brake cylinder portions is canceled. Of course, when the spools 6 and 7 are lowered for braking, the communication between the discharge ports 23a and 23b and the return port is cut off.

Further, reaction chambers 28a and 28b which open at the lower end surfaces of the primary spool 6 and secondary spool 7 are formed in the lower portions of the primary spool 6 and secondary spool 7.
Is provided. Then, the reaction plunger 2 fitted in each of the reaction chambers 28a and 28b.
The lower end surfaces of 9a and 29b are abutted against the upper end surface of the secondary spool 7 or the upper surface of the bottom lid 4. Further, the small-diameter portions 24a and 24b and the reaction chambers 28a and 28b are communicated with each other through small passage holes 30a and 30b, respectively.
The same hydraulic pressure as that of the discharge ports 23a and 23b can be introduced into 8a and 28b.

The operation of the brake valve for an all-hydraulic power brake system constructed as described above is as follows. When performing normal braking to stop the traveling vehicle, the brake pedal 11 is stepped on in the state shown by the chain line in FIG. 2, and the primary spool 6 and the secondary spool 7 are pushed through the pressing rod 13 and the transmission spring 19. To lower. As a result, the receiving ports 22a, 22b communicating with the brake accumulator and the discharge ports 23a, 23b communicating with the brake cylinder communicate with each other through the small diameter portions 24a, 24b formed on the outer peripheral surfaces of the intermediate portions of the spools 6, 7. . As a result, the pressure oil stored in the brake accumulator is sent to the brake cylinders provided on each wheel to perform braking.

Receiving ports 22a and 22b and discharge port 2
As the 3a and 23b communicate with each other, the discharge port 23 is provided in each of the reaction chambers 28a and 28b.
The same hydraulic pressure as that existing in the portions a and 23b acts. Therefore, the primary spool 6 and the secondary spool 7
Is pushed upward by a force corresponding to this hydraulic pressure, and the transmission spring 19 is compressed. Therefore, the brake pedal 11 receives a reaction force commensurate with the hydraulic pressure existing in the discharge ports 23a and 23b.

Next, in order to perform work while the vehicle is stopped, when operating the auxiliary braking device, the electromagnetic switching valve for the auxiliary brake (not shown) is opened, and the pilot port 27 and the pilot switching device (not shown) are opened. Communicate with the accumulator. Of course, when traveling, the auxiliary brake electromagnetic switching valve remains closed and the pilot port 2
Disconnect the communication between 7 and the pilot accumulator.

The electromagnetic switching valve for the auxiliary brake is opened,
As a result of communicating the pilot port 27 with the pilot accumulator, the pressure oil stored in the pilot accumulator is sent into the pilot cylinder 15 through the pilot port 27, and the pilot piston 16 is pushed out from the pilot cylinder 15. When the pilot piston 16 is pushed out in this manner, the primary spool 6 and the secondary spool 7 are displaced downward via the transmission spring 19 and the brake pedal 11
As in the case of stepping on the
2b and the discharge ports 23a and 23b communicate. As a result, the pressure oil in the brake accumulator is sent to the brake cylinders provided on each wheel, and braking is performed.

In this way, when the pressure oil in the brake accumulator is introduced into the discharge ports 23a, 23b and the hydraulic pressure in the reaction chambers 28a, 28b rises, the primary spool 6 and the secondary spool 7 are displaced in the opposite direction (raised). ) Force is generated, and the communication between the receiving ports 22a and 22b and the discharge ports 23a and 23b tends to be cut off. The movement of each of the spools 6 and 7 in the first cylinder portion 5 is performed by the pressing force based on the hydraulic pressure in the reaction chambers 28a and 28b and the hydraulic pressure introduced into the pilot cylinder 15 from the pilot accumulator. Stop when pressure equals. And in this state, the discharge port 23
The hydraulic pressure of a magnitude commensurate with the hydraulic pressure sent to the pilot port 27 is still being sent to the brake cylinder of each wheel through a and 23b.

In the structure shown in FIGS. 2 and 3, the valve case 1 is arranged vertically and the upper end surface of the pressing rod 13 is directly pressed by the roller 12 supported on the lower surface of the brake pedal 11. . On the other hand, a structure in which the valve case 1 is arranged in the horizontal direction is conventionally known. In the case of such a structure, the brake pedal 11
Is transmitted to the pressing rod 13 via a link mechanism (not shown), and the pressing rod 13 is directed toward the primary spool 6 and pressed in the horizontal direction. Also, in the case of a vehicle equipped with a brake pedal not only in the driver's seat but also in the passenger's seat, such as a training vehicle or a military vehicle used in the Self-Defense Forces,
In some cases, a configuration is adopted in which pressure oil is sent to the pilot port 27 as the brake pedal on the passenger side is depressed. Further, some work vehicles such as construction machines are provided with an auxiliary brake pedal for work (for inching) on the left side of a brake pedal for normal braking provided at a normal position. When working with such a working vehicle, the auxiliary brake pedal is depressed while depressing the accelerator pedal.
With the depression of the auxiliary brake pedal, the auxiliary braking device is actuated, and at the same time, the connection between the output shaft of the engine and the torque converter for the transmission is cut off. The torque converter should not be overloaded during the work performed while the accelerator pedal is being released. Even when the auxiliary brake pedal for such work is depressed, pressure oil is sent to the pilot port 27.

[0014]

In the case of the conventional structure shown in FIGS. 2 and 3, there is no particular problem in terms of function, but it is difficult to reduce the size while securing the braking force of the auxiliary braking device. The reason for this is as follows. In order to secure the braking force by the auxiliary braking device, it is necessary to increase the hydraulic pressure sent from the pilot port 27 into the pilot cylinder 15, or to increase the cross-sectional area (pressure receiving area) of the pilot cylinder 15. Of these, increasing the hydraulic pressure raises the manufacturing cost of the pilot accumulator, increases the size of the pump for generating the hydraulic pressure, and increases the power loss of the engine that operates the pump, so there is a limit. .

On the other hand, in order to increase the cross-sectional area of the pilot cylinder 15, it is necessary to reduce the thickness of the lower half of the pressing rod 13 or increase the outer diameter of the pressing rod 13. Among these, the thinning is limited in terms of reliability and durability of the pressing rod 13, and increasing the outer diameter causes an increase in size of the entire brake valve for the hydraulic brake system, which is not preferable. . In view of such circumstances, the brake valve for an all-hydraulic power brake device of the present invention has been invented in order to reduce the size while ensuring the braking force of the auxiliary braking device.

[0016]

A brake valve for an all-hydraulic power brake device according to the present invention is similar to the above-described conventional brake valve for an all-hydraulic power brake device. A first cylinder portion provided on the first cylinder portion, an inner end of the first cylinder portion on an inner side surface thereof, and an outer end of the valve case on an outer side surface thereof. A receiving port having an end opening communicating with a pressure oil source, an inner end of the first cylinder portion on an inner surface of the first cylinder portion, and an outer end of the valve case on an outer surface of the valve case are opened. And a discharge port whose outer end opening communicates with the brake cylinder, and an oil-tight and axially displaceable fit inside the first cylinder portion. On displacement A spool for communicating the receiving port and the discharge port with each other, a return spring for pressing the spool to the other end side of the valve case in order to cut off the communication between the receiving port and the discharge port, A second cylinder portion provided on the inner side of the half portion, and fitted inside the second cylinder portion so as to be displaceable in the axial direction,
A pressing rod having one end protruding from one end opening of the second cylinder part to the outside of the valve case and the other end protruding from the other end opening of the second cylinder part to the first cylinder side. And a transmission spring that is provided between the other end of the pressing rod and the end of the spool and that transmits the movement of the pressing rod to the spool and that has a greater elastic force than the return spring, and the pressing rod. A pilot piston that is movably supported on the other end side portion in the axial direction with respect to the pressing rod, and that pushes the transmission spring toward the spool based on the displacement toward the first cylinder portion side, A pilot cylinder provided between the pilot piston and the pressing rod, and a part of the valve case which opens to the outer side surface and communicates with the pilot cylinder. And a lot port.

In particular, in the brake valve for an all-hydraulic power brake device of the present invention, the pilot piston has a bottomed cylindrical main portion with one end open. The other end of the pressing rod is oil-tightly fitted inside the main part, and the pilot cylinder is composed of a space surrounded by the inner surface of the main part and the other end of the pressing rod. . The pilot port and the pilot cylinder communicate with each other through a center hole opened on the other end surface of the pressing rod.

[0018]

The action of the brake valve for an all-hydraulic power brake device of the present invention configured as described above when the vehicle is normally braked to stop the running vehicle, and the work while the vehicle is stopped The operation of operating the auxiliary braking device is the same as that of the conventional brake valve for the all-hydraulic power brake device described above, in order to perform the above-mentioned operation or to perform the braking when the brake pedal provided in the passenger seat is depressed. . Particularly, in the case of the brake valve for an all-hydraulic power brake device of the present invention, the other end of the pressing rod is oil-tightly fitted inside the bottomed cylindrical main part that constitutes the pilot piston, and the main part is Since the pilot cylinder is constituted by the space surrounded by the inner surface of the pilot rod and the other end surface of the pressing rod, the sectional area of the pilot cylinder can be made equal to the sectional area of the pressing rod. Therefore, it is possible to reduce the size while ensuring the braking force of the auxiliary braking device.

[0019]

FIG. 1 shows an embodiment of the present invention. The feature of the present invention resides in the structure of the portion where the pilot piston 31 constituting the auxiliary braking device is combined with the lower end portion of the pressing rod 13 in order to achieve the size reduction while ensuring the braking force of the auxiliary braking device. Since the structure and operation of the other parts are the same as the conventional structure described above, the illustration and description of the overlapping parts will be omitted or simplified, and the characteristic part of the present invention will be mainly described below.

The pilot piston 31, which constitutes an auxiliary braking device for performing work while the vehicle is stopped,
It is provided with a bottomed cylindrical main portion 32 having an open upper end which is one end. An outward flange-shaped engagement portion 33 is formed on the outer peripheral surface of the intermediate portion of the main portion 32, and the upper end of the transmission spring 19 is abutted against the lower surface of the engagement portion 33. On the other hand, a small diameter portion 34 is formed at the lower end of the pressing rod 13, and the small diameter portion 34
The main portion 32 is oil-tightly fitted on the outer surface. In the case of the illustrated embodiment, a plurality of concave grooves are formed on the outer peripheral surface of the small diameter portion 34 over the entire circumference of the small diameter portion 34.
A labyrinth seal is provided between the outer peripheral surface of No. 4 and the inner peripheral surface of the main portion 32.

The pilot cylinder 15a for feeding pressure oil during the operation of the auxiliary braking device has a lower end surface of a small diameter portion 34 formed at the inner surface of the main portion 32 and the lower end portion (the other end portion) of the pressing rod 13 ( The other end surface) and a space surrounded by. Further, the pilot port 27 provided on the side surface of the upper case 2 and the pilot cylinder 15a have a central hole 35 opened at the lower end surface of the pressing rod 13.
Through each other. That is, the pressing rod 13
A large diameter portion 36 is formed on the inner peripheral surface of the second cylinder portion 14 through which the through hole is inserted, and the outer peripheral side opening of the branch hole 37 communicating with the central hole 35 is opposed to the large diameter portion 36. Further, the oil supply hole 38 communicating with the pilot port 27 is formed in the large diameter portion 3
I am familiar with 6. Therefore, the pilot port 27 and the pilot cylinder 15a remain in communication with each other regardless of whether the pressing rod 13 is moved up and down.

In the illustrated embodiment, the upper half of the auxiliary transmission spring 39 is engaged with the lower half of the main portion 32. The auxiliary transmission spring 39 is provided between the locking portion 33 and the upper surface of the lower locking plate 18 locked to the upper end portion of the primary spool 6 when the transmission spring 19 is compressed to a certain extent or more. Bulge. Furthermore, the upper end portion of the return spring 21 is abutted against the lower end portion of the locking bracket 40 that is locked to the intermediate portion of the pressing rod 13. The locking bracket 40 is formed into a substantially cylindrical shape by drawing a metal plate, and the upper end of the locking bracket 40 is locked to the intermediate portion of the pressing rod 13.
Further, a plurality of claw pieces 41, 41 are formed on the outer peripheral surface of the lower end portion of the locking bracket 40 so as to intermittently project in the circumferential direction. The upper end of the return spring 21 is in contact with the lower surfaces of the claw pieces 41, 41.

In the case of the brake valve for an all-hydraulic power brake device of the present invention having the above-described structure, the inside of the bottomed cylindrical main part 32 forming the pilot piston 31 is provided at the lower end of the pressing rod 13. Since the pilot cylinder 15a is configured by fitting the formed small diameter portion 34 in an oil-tight manner, the cross-sectional area of the pilot cylinder 15a can be made equal to the cross-sectional area of the small diameter portion 34. The cross-sectional area of the small diameter portion 34 can be made larger than the cross-sectional area of the pilot cylinder 15 (FIGS. 2-3) in the conventional structure. Therefore, it is possible to reduce the size while ensuring the braking force of the auxiliary braking device. In other words,
Since the braking force that can be generated in the pilot cylinder 15a portion becomes large, this pilot cylinder 15a
It is possible to lower the hydraulic pressure fed into the cylinder a, reduce the manufacturing cost of the pilot accumulator, downsize the pump for generating the hydraulic pressure, and reduce the power loss of the engine that operates the pump.

In the above-mentioned embodiment, the valve case 1 is arranged in the vertical direction, but the present invention is not limited to such a structure and can be applied to a structure in which the valve case 1 is arranged in the horizontal direction. Of course. Further, it is also clear that a configuration can be adopted in which pressure oil is sent to the pilot port 27 when the brake pedal provided in the passenger seat is depressed. Therefore, the upper and lower relations in the description of the above embodiment are only for the embodiment in which the valve case 1 is arranged in the vertical direction, and do not particularly limit the technical scope of the present invention based on the claims.

[0025]

The brake valve for an all-hydraulic power brake device according to the present invention is constructed and operates as described above, so that it is possible to reduce the size while ensuring the braking force of the auxiliary braking device. The degree of freedom in designing the hydraulic power brake device is improved.

[Brief description of the drawings]

FIG. 1 is a partial vertical sectional side view corresponding to a portion A in FIG. 2, showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional side view showing one example of a conventional structure.

FIG. 3 is an enlarged view of a portion A in FIG. 2;

[Explanation of symbols]

 1 Valve Case 2 Upper Case 3 Lower Case 4 Bottom Cover 5 First Cylinder Section 6 Primary Spool 7 Secondary Spool 8 Mounting Board 9 Bolt 10 Horizontal Shaft 11 Brake Pedal 12 Roller 13 Push Rod 14 Second Cylinder Section 15, 15a Pilot Cylinder 16 Pilot piston 17 Upper locking plate 18 Lower locking plate 19 Transmission spring 20 Locking plate 21 Restoring spring 22a, 22b Receiving port 23a, 23b Discharge port 24a, 24b Small diameter portion 25 Locking plate 26 Restoring spring 27 Pilot port 28a, 28b Reaction chamber 29a, 29b Reaction plunger 30a, 30b Small through hole 31 Pilot piston 32 Main part 33 Locking part 34 Small diameter part 35 Center hole 36 Large diameter part 37 Branch hole 38 Oil supply hole 39 Auxiliary transmission spring 40 Locking bracket 41 Claw piece

Claims (1)

[Claims] 1. A valve case, a first cylinder portion provided inside one half of the valve case, a part of the inner surface of the first cylinder part having an inner end, and a part of the outer surface of the valve case. The outer end of the valve case is opened, and the outer end opening of the receiving port communicates with a pressure oil source; A discharge port that is provided with its outer end partially opened on the outer surface and has its outer end opening communicating with the brake cylinder, and inside the first cylinder section in an oil-tight and axial direction. A spool that is fitted so as to be freely displaceable, and that connects the receiving port and the discharge port based on the displacement of the valve case toward the one end side, and the spool that disconnects the communication between the receiving port and the discharge port. Above valve A return spring that presses against the other end of the case, a second cylinder portion provided inside the other half of the valve case, and a displaceably fitted axially inside the second cylinder portion, A pressing rod having one end protruding from one end opening of the second cylinder portion to the outside of the valve case, and the other end protruding from the other end opening of the second cylinder portion to the first cylinder side. A transmission spring that is provided between the other end of the pressing rod and the end of the spool and that transmits the movement of the pressing rod to the spool and that has a greater elastic force than the return spring; A pilot piston movably supported by the other end side portion in the axial direction with respect to the pressing rod, and pressing the transmission spring toward the spool based on the displacement toward the first cylinder portion side. , A brake valve for a full hydraulic power brake device, comprising a pilot cylinder provided between the pilot piston and the pressing rod, and a pilot port which opens to a part of an outer surface of the valve case and communicates with the pilot cylinder In the above, the pilot piston has a bottomed cylindrical main part with one end open, and the other end of the pressing rod is oil-tightly fitted inside the main part. It is constituted by a space surrounded by the inner surface of the main portion and the other end surface of the pressing rod, and the pilot port and the pilot cylinder communicate with each other through a center hole opened in the other end surface of the pressing rod. Brake valve for all-hydraulic power brake device characterized by