JP2515711B2 - Brake pressure holding device for vehicle - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an improvement of a vehicle brake pressure holding device that causes a vehicle running brake to act as a parking brake means.

(Background of the Invention) Generally, vehicles are equipped with parking brakes except for special vehicles, but they are equipped with special vehicles, that is, special machines that are driven by the driving force of the engine of the vehicle. In a specially equipped vehicle such as a mixer truck that drives a machine equipped with the engine running, in order to park the vehicle, use a transmission for running the vehicle in a neutral position. Must be set to.

That is, unlike a general passenger vehicle equipped with a manual transmission, it is not possible to shift the transmission to the low position or the reverse position for parking during parking.

Therefore, when parking a conventional specially equipped vehicle, only a manual parking brake is a safety measure during parking, and in this case, vibration of the entire vehicle caused by driving a machine equipped in the specially equipped vehicle by the engine of the vehicle , There is a risk of loosening the manual parking brake.

Therefore, as one conventional method for solving this problem, the brake pressure is maintained while the traveling brake, which is inevitably installed in the vehicle, is operated, and is used as the parking brake means. However, depending on the way the brakes for traveling are operated, there is a drawback in that the brakes are held at excessive brake pressure to be used as parking brake means. As a result, the traveling brake may be damaged due to fatigue and the like, and as a result, the vehicle may start to slip.

Therefore, a vehicle brake pressure holding device that does not hold the running brake at a high pressure of a certain value or higher and that can increase the brake pressure is already known as in Japanese Utility Model Publication No. 64-28358. However, in this invention, the purpose is realized by separately providing a mechanism for releasing the pressure at the time of high pressure, and the control mechanism is complicated.

For example, the opening / closing part that opens and closes the communication of air requires high processing accuracy at the time of manufacturing, but the above-mentioned invention has a plurality of opening / closing parts, and there are many places where the processing accuracy needs attention, so the device is expensive. It could be something.

Therefore, in order to always reliably park a specially-equipped vehicle such as a mixer truck, it is automatically decompressed so that the traveling brake used as the parking brake means cannot be kept under an excessive pressure, and the vehicle is kept at an appropriate pressure. At the same time, the operating force of the traveling brake at the beginning of parking is weak, and even if the operating pressure is kept at a low pressure, the brake pressure is increased only by re-operating the traveling brake without using manual means, and an appropriate pressure is obtained. The development of a parking brake with a simple structure that can be modified as described above has been strongly demanded for safe operation of various specially equipped vehicles, which are increasingly used.

(Object of the Invention) An object of the present invention is to provide a vehicle brake pressure holding device which can simplify the structure by simplifying the piping system by using only one on-off valve. .

(Characteristics of the invention) In order to achieve the above object, the present invention provides a first pressure chamber communicating with a brake pressure input port, a second pressure chamber communicating with a brake pressure output port, and the first pressure chamber. Flow hole provided between the pressure chamber and the brake pressure output port, an open / close valve for opening / closing the flow hole, the open / close valve is forcibly opened during traveling, and the open / close valve is opened / closed during parking. And a control means for parking which is controlled so as to enable the opening and closing of the opening and closing valve in association with movement, and the brake pressure of the second pressure chamber to receive the closing valve of the opening and closing valve. A plunger piston which is pressed in the driving direction, a floating piston which receives the brake pressure of the first pressure chamber and presses the plunger piston in the valve opening driving direction of the on-off valve via a first compression spring, The plunger piston And a second compression spring for pressing the opening / closing valve in the valve closing driving direction so that the brake pressure can be increased / decreased and held only by opening / closing one brake control fluid flow hole. It is characterized by having done.

(Embodiment of the Invention) FIG. 1 is a configuration diagram of a vehicle brake control system for explaining an embodiment of the present invention.

The compressor 1 is driven by a driving force of an engine (not shown), and an air tank 3 is connected by a connecting pipe 2.
When the air pressure in the air tank 3 drops below a certain value, it automatically operates to compress the air and
Send to.

When the driver depresses the brake pedal 5, the brake valve 4 sends air pressure proportional to the amount of depression to the pressure holding devices 6 and 7 and the air masters 8 and 9.

The air masters 8 and 9 convert air pressure into hydraulic pressure and control the front wheel brakes 10 and 11 and the rear wheel brakes 12 and 13 of the vehicle, respectively.

The pressure holding devices 6 and 7, which are the object of the present invention, are connected in tandem between the brake valve 4 and the air masters 8 and 9 by the connecting pipe 2.

2A and 2B are structural views of the pressure holding devices 6 and 7, wherein FIG. 2A is a sectional view and FIG. 2B is a diagram showing internal dimensions. The operation of the pressure holding devices 6 and 7 according to one embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

When the vehicle is traveling, etc., the lever 14 for manually operating the parking brake is raised so that the rod
Since the first pressure chamber 17 communicating with the brake pressure input port 16 and the vent hole 18 are communicated with each other, the pressure holding devices 6 and 7 are connected to each other by the air pressure from the brake valve 4. Directly to the air masters 8 and 9.

Further, the vent hole 18 communicates with the brake pressure output port 19 and also communicates with the second pressure chamber 20 via the communication passage 21, so that the plunger piston 22 is pushed by the air pressure from below.

The floating piston 23 is arranged in the first cylinder hole 24 so as to be vertically movable, and the plunger piston 22
It slides with the neck portion 25 of the as the sliding axis. The floating piston 23 receives the air pressure in the first pressure chamber 17 and is pressed downward. The plunger piston 22 has a first cylinder bore 24
The second cylinder hole 26 having a smaller diameter is arranged so as to be vertically movable. The first cylinder hole 24 and the second cylinder hole 26 are communicated with each other, and a chamber 27 is formed between the floating piston 23 and the plunger piston 22.

The floating piston 23 and the plunger piston 22 are connected by a first compression spring 28 located in the chamber 27, and thus the floating piston 23
When the air pressure in the first pressure chamber 17 becomes high, the first pressure chamber 17 tends to displace the plunger piston 22 via the first compression spring 28. In addition, the plunger piston
22 is biased upward by a second compression spring 29, and its head end 30 is constantly pressed against the rod 15.

A valve element 31 is provided below the head end 30 and constitutes an opening / closing valve together with a valve seat 32 which is a corner of the vent hole 18, the head end 30 and the neck 25. The plunger piston 22, the floating piston 23 and the rod 15 are made airtight by a rubber seal 33.

The air pressure sent to the air masters 8 and 9 via the pressure holding devices 6 and 7 is converted into hydraulic pressure in the air masters 8 and 9, and is transferred to the wheel cylinders 34 and 35 of the front wheels and the wheel cylinders 36 and 37 of the rear wheels. Transmitted. By operating the wheel cylinders 34 to 37, the brakes 10 to 13 simultaneously operate.

As described above, when the lever 14 is in the upper position, that is, in the position where the parking brake is released, such as when the vehicle is traveling, the first pressure chamber 17 and the vent hole 18 are in communication, and the brake pedal 5 is in communication. By stepping on, the air pressure is sent directly from the brake valve 4 to the air masters 8 and 9 via the pressure holding devices 6 and 7, and the brakes 10 to 13 work in proportion to the amount of depression of the brake pedal 5.

In FIG. 2 (b), the diameter of the floating piston 23 is D ₁ , the diameter of the plunger piston 22 is D ₂ , and the vent hole 18 is shown.
The diameter of D ₃ and the diameter of the neck 25 of the plunger piston 22.
D ₄ , the set load of the first compression spring 28 is W ₁ , and the set load of the second compression spring 29 is W ₂ .

In order to park the vehicle, if the lever 14 is pushed down while stepping on the brake pedal 5 with the strength required to hold the stopped vehicle in a stopped state, the set pressure P ₁ ( As the maximum holding pressure, air having a pressure value set in advance according to the type of vehicle or the like, which will be described later) P ₂ is sent from the brake valve 4 to the pressure holding devices 6 and 7, and is fed to the first pressure chamber 17. Air pressure is introduced.

The plunger piston 22, the product of the pressure P ₂ and the effective pressure receiving cross-sectional area [pi] D ₂ ^2/4 of the plunger piston 22, and push up force upward by the set load W ₂ of the second compression spring 29, the plunger piston 22 Effective area of neck 25 of πD ₄ ² /
The sum of the forces that push the plunger piston 22 downwards, which is the pressure P ₂ multiplied by 4, acts as P ₂ × π (D ₂ ² -D ₄ ² ) / 4 + W ₂ .

In addition, the floating piston 23 is connected to the first pressure chamber 17
Force of the pressure P _2, the product of the pressure P ₂ and the effective pressure receiving cross-sectional area [pi / 4 floating piston ^{_{23 (D 1 2 -D 4 2}} ), of ^{_{P 2 × π (D 1 2}} -D 4 2) / 4 It is pushed down by the first compression spring 28
Is transmitted to the plunger piston 22 via.

When the pressing force of the floating piston 23 is larger than the set load W _{1 of} the first compression spring 28, the floating piston 23 slides downward and the first compression spring 28 bends.

Here, when P ₂ <P ₁ , the pushing force of the floating piston 23 is P ₂ × π (D ₁ ² -D ₄ ² ) / 4, and the pushing force of the plunger piston 22 is P ₂ × π (D ₂ ² -D _{Since 4} ² ) / 4 + W ₂ becomes large, the plunger piston 22 brings the valve element 31 into contact with the valve seat 32 of the vent hole 18 to close the vent hole 18.

The force that closes the vent hole 18 is the difference between the pushing force of the plunger piston 22 and the pushing force of the floating piston 23 P ₂ × π (D ₂ ² -D ₄ ² ) / 4 + W ₂ -P ₂ × π (D ₁ ² -D ₄ ² ) / 4.

If the brake pedal 5 is released in this state, the ventilation hole 18
In the closed state, compressed air is released from the brake valve 4 and the first pressure chamber 17 becomes atmospheric pressure.

At this time, since the pressure applied to the floating piston 23 becomes atmospheric pressure, the pressing force of the floating piston 23 becomes the set load W ₁ of the first compression spring 28. Therefore, the liquid from the ^{_{P 2 × πD 2 2/4}} + W 2 -P 2 × πD 3 2/4-W becomes pressure holding state by closing the vent hole 18 in the _first force, air master 8,9 This air pressure The pressure is generated and the brake is held.

Next, by depressing the brake pedal 5 hard,
A high pressure P ₃ higher than the set pressure P ₁ of the pressure holding devices 6 and 7 passes from the brake valve 4 through the first pressure chamber 17 and the second pressure chamber.
20 and the air master 8 and 9, when the brake pressure is working strongly, the floating piston 23, pressure P ₃
Slide down by.

At this time, a force of P ₃ × π (D ₁ ² -D ₄ ² ) / 4 acts on the floating piston 23 in the direction of pushing down the plunger piston 22.

Further, a force of P ₃ × π (D ₂ ² -D ₄ ² ) / 4 + W ₂ acts on the plunger piston 22 in the upward direction.

At this time, even if the lever 14 is lowered and the rod 15 is lifted so as to close the ventilation hole 18, if P ₃ > P ₁ , the plunger piston 22 is P ₃ × π (D ₁ ² -D ₄ ² ) It is pushed down by the force of / 4− {P ₃ × π (D ₂ ² −D ₄ ² ) / 4 + W ₂ }.

Therefore, when the first pressure chamber 17 is in communication with the air masters 8 and 9, that is, when the air pressure from the brake valve 4 is equal to or higher than the set pressure P ₁ , the pressure cannot be maintained.

When the brake pedal 5 is loosened from this state, the first pressure chamber 17 and the second pressure chamber 20 are decompressed, and when the pressure becomes P ₁ or less, the plunger piston 22 pushes upward as described above. As a result, the vent hole 18 can be closed. That is, when the pressure is reduced to the set pressure P ₁ or less, the pressure is automatically maintained.

In other words, even if the brake pedal 5 of the brake valve 4 is strongly depressed so that the discharge air pressure P ₁ of the brake valve 4 or more is reached, the maximum holding pressure when the pressure is held is always P ₁ .

When the pressure is set as the parking brake means by the set pressure of the pressure holding devices 6, 7, that is, the maximum holding pressure P ₁ , the brake is not always held at the pressure of P ₁ or more, and therefore the vehicle is used as the parking brake means. When the vehicle brake is used, it is effective to prevent the vehicle brake from being damaged by strongly operating the vehicle brake for a long time.

Furthermore, when the vehicle is parked at a weak pressure P ₄ where the holding pressure is P ₁ > P ₂ > P ₄ , and when a large number of heavy objects are loaded on the vehicle, it is known that the vehicle braking force is relatively weak. When the brake pedal is depressed, depress the brake pedal 5 to increase the holding pressure P ₂
, The air pressure acts on the first pressure chamber 17, and the floating piston 23 is pushed down by the force of P ₂ × π (D ₁ ² -D ₄ ² ) / 4, and that force is applied to the plunger piston.
22 is transmitted to, the plunger piston 22, the ^{_{P 2 × π (D 1 2}} -D 4 2) / 4 + P 2 × πD 4 2/4-P 2 × πD 3 2/4 depressed is the force in work.

At this time, the plunger piston 22, P ₂ pressure below
The P _{4, ^{upward, P 4 × πD 2 2/}} 4-P 4 × πD 3 2/4 + W 2 beauty upward force is acting. At this time, when it is _{P 2> P 4, P 2} × π (D 1 2 -D 4 2) / 4 + P 2 × πD 4 2/4-P 2 × πD 3 2/4> P 4 × πD
A ^{_{2 2/4-P 4 ×}} πD 3 2/4 + W 2, the plunger piston 22 will be pushed down is down.

Therefore, the pressure of P ₂ is sent to the air masters 8 and 9, and as described above, the first pressure chamber 17 and the second pressure chamber 20 have the same pressure.
When the air pressure becomes P ₂ , the air pressure increased from P ₄ to P ₂ closes the vent hole 18, and when the brake pedal 5 is loosened, the brake is held in this state.

In this way, when the brake is to be strengthened, the brake pedal 5 of the brake valve 4 is depressed to move the ventilation hole 18
The pressure can be increased by opening the.

To release the brake holding pressure, the brake pedal 5 of the brake valve 4 is depressed, the pushing force of the lever 14 is lightened, and the lever 14 is pushed up and released. At this time, the brake can be released without stepping on the brake pedal 5, but if the vehicle is vibrated, the lever 14
It is possible that the holding pressure may be released during parking, so it is safer to set the effective pressure receiving area of the plunger piston 22 so that it cannot be released without stepping on the brake pedal 5. To be

The set pressure of the pressure holding devices 6 and 7, that is, the maximum holding pressure P ₁ is the set load of the first compression spring 28.
W _1, the set load W ₂ of the second compression spring 29, the effective pressure receiving cross-sectional area of the plunger piston 22 [pi] D ₂ ^2/4, the effective pressure receiving cross-sectional area ^{_{π (D 1 2 -D 4 2}} ) of the floating piston 23/4 and contact is determined by the effective cross-sectional area πD ₃ ^2/4.

That is, W ₂ > W ₁ and π (D ₁ ² −D ₄ ² ) / 4> π (D ₂ ² −D ₄ ² ) / 4.

When the low pressure P ₄ is less than the so-called set pressure P ₁ , W ₂ > P ₄ × π (D ₁ ² -D ₄ ² ) / 4-P ₄ × π (D ₂ ² -D ₄ ² ) / 4 or W ₂ > W ₁ -P ₄ × π (D ₂ ² -D ₄ ² ) / 4 (when W ₁ > P ₄ × π (D ₁ ² -D ₄ ² ) / 4) and each effective pressure cutoff The spring pressing force W ₂ becomes stronger than the pressing force due to the area, and the ventilation hole 18 is closed.

Further, when the high pressure P ₃ , that is, the so-called set pressure P ₁ or more, W ₂ <P ₃ × π (D ₁ ² -D ₄ ² ) / 4-P ₃ × π (D ₂ ² -D ₄ ² ) / 4 Since the pressing force generated by each effective pressure receiving cross-sectional area becomes larger than the spring pressing force W ₂ , the vent hole 18 will not close.

Therefore, the set pressure of the pressure holding devices 6, 7, that is, the maximum holding pressure P ₁ of the brake can be freely changed by changing the effective pressure receiving cross-sectional area and the set load of the spring. It is possible to set this in consideration of the condition of.

According to this embodiment, the brake pressure is increased / decreased and held only by opening / closing the opening / closing valve at one place, so that the structure can be simplified. Further, even in the low pressure P ₄ brake pressure than the set pressure P _1, because anyway held, it is possible to ensure the minimum safety.

In the illustrated embodiment, the lever 14 and the rod 15
Corresponds to the parking control means of the present invention, the ventilation hole 18 corresponds to a flow hole, and the neck portion 25, the head tip 30, the valve body 31, and the valve seat 32 correspond to an opening / closing valve.

In the above description, an example in which the front wheel and the rear wheel are separately pressure-held has been described, but as shown in FIG. 3, it is also possible to simultaneously pressure-hold two systems.

In addition, as shown in FIG. 4, instead of the manual lever 14, the solenoid 38 is used to slide the rod 15 up and down, and the sensor 39 and the control circuit 40 operate as shown in the flowchart of FIG. It is also possible to automatically hold and release the pressure by a sequence.

Furthermore, in the above embodiment, an example of use for an air-over-hydric brake vehicle has been described.
Alternatively, it can be used in a hydraulic brake vehicle.

(Effect of the invention) As described above, according to the present invention, the first pressure chamber communicated with the brake pressure input port, the second pressure chamber communicated with the brake pressure output port, and the first pressure chamber Flow hole provided between the pressure chamber and the brake pressure output port, an open / close valve for opening / closing the flow hole, the open / close valve is forcibly opened during traveling, and the open / close valve is opened / closed during parking. And a control means for parking which is controlled so as to enable the opening and closing of the opening and closing valve in association with movement, and the brake pressure of the second pressure chamber to receive the closing valve of the opening and closing valve. A plunger piston which is pressed in the driving direction, a floating piston which receives the brake pressure of the first pressure chamber and presses the plunger piston in the valve opening driving direction of the on-off valve via a first compression spring, The plunger piston And a second compression spring for pressing the opening / closing valve in the valve closing driving direction so that the brake pressure can be increased / decreased and held only by opening / closing one brake control fluid flow hole. Therefore, the structure can be simplified by using only one on-off valve. Further, since the pressing force of the plunger piston for closing the on-off valve is obtained from the brake pressure of the second pressure chamber communicating with the brake pressure output port, the piping system can be simplified.

[Brief description of drawings]

FIG. 1 is a vehicle brake control system diagram for explaining an embodiment of the present invention, FIG. 2 is a structural diagram of a pressure holding device, and FIG.
FIG. 4 is a vehicle brake control system diagram for explaining another embodiment of the present invention, FIG. 4 is the same vehicle brake control system diagram, and FIG. 5 is an operation sequence of the vehicle brake control system diagram of FIG. It is a flow chart to do. 6,7 …… Pressure holding device, 14 …… Lever, 15 …… Rod, 1
6 ... Brake pressure input port, 17 ... First pressure chamber, 18 ...
… Vent hole, 19 …… Brake pressure output port, 20 …… Second pressure chamber, 21 …… Communication passage, 22 …… Plunger piston, 23…
… Floating piston, 24 …… first cylinder hole,
25 …… neck, 26 …… second cylinder hole, 27 …… chamber, 28…
… First compression spring, 29 …… Second compression spring, 30 …… Head tip, 31 …… Valve element, 32 …… Valve seat, 33 ……
Rubber seal, 38 …… solenoid, 39 …… sensor, 40 ……
Control circuit.

Claims (1)

(57) [Claims] 1. A vehicle brake which is tandemly inserted into a control system of a traveling brake for braking traveling of a vehicle so that a brake pressure in an operating state of the traveling brake can be held by using a parking control means. A pressure holding device, the first pressure chamber communicating with the brake pressure input port, the second pressure chamber communicating with the brake pressure output port, the first pressure chamber and the brake pressure output port A flow hole provided between the flow path, an open / close valve that opens and closes the flow hole, and a parking controlled so that the open / close valve is forcibly opened during traveling so that the open / close valve can be opened / closed during parking. And a plunger piston that drives the on-off valve to open and close in conjunction with movement, and receives the brake pressure of the second pressure chamber, and is pressed in the valve closing drive direction of the on-off valve. Brake of the first pressure chamber A floating piston that receives force and presses the plunger piston in the valve opening drive direction of the opening / closing valve via a first compression spring, and a second piston that presses the plunger piston in the valve closing drive direction of the opening / closing valve. A brake pressure holding device for a vehicle, comprising a compression spring.