JPS6048377B2 - Safety device in dual air brake system for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an improvement of a safety device in a two-system air brake system for a vehicle that allows the air brakes of the other system to continue operating normally even if one system of the air brake fails. It is related to.

In air brake systems for vehicles, pressurized air generated by a single compressor is stored in two independent air reservoirs, and these two air reservoirs are used as pressure sources to operate two systems of air brakes. It is done a lot.

The two air reservoirs are usually sized to be able to store enough pressurized air to perform the control several times, and in this way, it is possible to prevent piping from bursting. Even if one system of air brakes fails (the brakes do not operate because the pressure does not rise sufficiently), the other brake can be activated several times, making it possible to bring the vehicle to a halt. Therefore, vehicle safety can be improved. However, in conventional dual-system air brake systems, if one system fails, all the compressed air supplied from the compressor is
Since it leaks from the damaged part on the failed side, pressurized air is not supplied to the air reservoir on the normal side.
After the pressurized air stored in the air reservoir on the normal side is exhausted, both brake systems will not operate.

Therefore, in the past, a pressure gauge was installed in the air brake circuit, and when the pressure dropped below a predetermined value, the driver was notified by an indication from the pressure gauge or by an alarm, and the vehicle was stopped based on this information. Then, either the damaged part was repaired or the cock installed in the compressed air passage to the air reservoir on the failed side was closed. However, if the driver neglects to monitor the pressure gauge or ignores the warning for some reason, such measures will not be taken and the vehicle will continue to drive without brakes, resulting in serious damage. There was a risk of causing an accident. In order to eliminate such drawbacks of conventional brake systems, the inventors of the present invention have developed a system in which when one air brake in a dual-system air brake system fails, the air brake on the failed side is automatically activated. We previously invented a safety device that disconnects the compressor from the compressor, so that even if either of the two systems fails, the other system can continue to operate normally. This is currently pending as Japanese Patent Application No. 53-15110, and its feature is that the pressurized air generated by one compressor is divided into two parts, and a first and a second non-return check are respectively applied. Air is supplied to the first and second air reservoirs through the valve, and two independent systems of air brakes are operated using these first and second air reservoirs as pressure sources. In a two-system air brake system for a vehicle, the first and second check valves allow the first and second check valves to connect the first and second check valves to the pressure air passage on the compressor side, respectively. second j
A differential piston that receives the pressure of the air reservoir and operates due to the difference between these two pressures;
When the pressure in the first air reservoir becomes lower than the pressure in the second air reservoir by more than a certain limit and the differential piston moves from the neutral position, a first air reservoir that cuts off the pressure air passage to the first air reservoir; (4) when the pressure in the second air reservoir becomes lower than the pressure in the first air reservoir by more than a certain limit and the differential piston moves from the neutral position, the pressure in the second air reservoir decreases; A safety device including a second cut valve that cuts off the air passage is inserted, and when one air brake system fails, the air brake system on the failed side is disconnected from the compressor, and the normal side is removed. The air brakes were supplied with pressurized air as usual. However, subsequent research revealed that the safety device of the previous invention had some defects.

That is, in the safety device according to the previous invention, (1)
Because the differential piston was held in the neutral position by balancing the elastic force of a compression spring, etc., it was difficult to accurately hold the differential piston in the neutral position (as a result of 2. (3) It is difficult to accurately set the pressure difference between the first and second air reservoirs when the valve closes, and (3) it is difficult to balance the force that moves the differential piston based on the pressure difference between the first and second air reservoirs. is only the difference in the elastic force of the compression spring, etc., and has nothing to do with the preload that is pre-compressed by the compression spring, etc., so in order to generate a predetermined force, the spring constant of the compression spring, etc. It is necessary to make the stroke of the differential piston larger or to make the stroke of the differential piston larger, which tends to increase the size of the compression spring, etc. or the main body of the safety device.The present invention solves the above problems. In order to hold the differential piston in the neutral position in the safety device, it is not a simple compression spring, but a compression spring and a compression spring that compresses the compression spring and It is characterized by the use of a spring device consisting of a regulating means that precisely regulates the length and generates a predetermined preload.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be explained in more detail based on the drawings.

In FIG. 1, 1 is a compressor, and compressed air generated by the compressor 1 is sent to a wet tank 4 via a pipe 2 and a check valve 3. The high temperature pressurized air supplied from the compressor 1 is transferred to the wet tank 4.
It is cooled and moisture is condensed out. Reference numeral 5 denotes a pressure regulator, which releases the suction valve of the compressor 1 when the pressure of the wet tank 4 rises to a predetermined value, thereby stopping the compressor 1 from supplying pressurized air.

The pressure air from which moisture has been removed in the wet tank 4 is led to a safety device 100 through a pipe 6 and then divided into two parts, one of which passes through a pipe 7 and a check valve 8 to a first air reservoir 9. The other air is sent to a second air reservoir 13 via a conduit 11 and a check valve 12.

Also, the pressure of air reservoirs 9 and 13 is that! Pipe line 14 respectively
, 15 to the safety device 100. Safety device 1
The internal structure of 00 will be detailed later. The pressure air once stored in the first air reservoir 9 is transferred to the brake pedal 1
6 is depressed, the air is sent to the air booster 21 via pipes 1.7, operating valve 18 and pipe 19, where it is converted to hydraulic pressure, and then sent to the front wheel cylinders 23 via pipe 22. , activate the front brake.

The above will be collectively referred to as the front brake system. Note that 24 is a brake free reservoir. Like the front brake system, the rear brake system is also composed of a second air reservoir 13, a conduit 25, an operating valve 18, a conduit 26, an air booster 27, a brake fluid reservoir 28, a conduit 29, a rear wheel cylinder 31, etc. There is.

The safety device 100 is shown in an enlarged view in FIG.

In the figure, 101 is a main body, a through hole is bored in the main body 101, and openings at both ends of the through hole are respectively plug 1.
Blocked by 02,103. A piston 104 is slidably fitted into the main body 101. The piston 104 has two heads 105 and 106 connected to the piston rod 1.
07, and valve elements 108 and 109 are fixed to opposing surfaces of the heads 105 and 106.
At both ends of the piston 104, coil springs 113,
114, spring seats 115, 116 which receive one end of the coil springs 113, 114 and are normally seated on the stepped surfaces 111, 112 of the main body and are movable only in a direction to further compress the coil springs 113, 114; and the plug. A spring device 143, ι144 is disposed, which is composed of positionally fixed spring seats 141, 142 formed on the spring seats 102, 103, and the piston 104 is connected to the spring seats 115, 116 and the piston head 1.
05 and 106, and are held at a neutral position with a slight gap between them. Piston head 105, 106, plug 1
02, 103 and the main body 101 is a seal ring 11.
7, 118, 119, 121, etc., and as a result, the empty space in the main body 101 is sealed by the first pressure chamber 122,
It is divided into a second pressure chamber 123 and a central air chamber 124. The pressurized air guided by the pipe 6 enters the central pressure chamber 124 from the boat 125 and enters the central pressure chamber 1
24, one is sent out from the boat 126 toward the first air reservoir 9, and the other is sent out from the boat 127 toward the second air reservoir 13.
These air passages are connected to valves 108 and 109 fixed to the piston heads 106 and 107, and a stepped surface 12 of the main body 101.
8,129 and the first cut valve 13
3 and a second cut valve 134.

Further, the pressure in the first air reservoir 9 is guided from the boat 135 to the first pressure chamber 122 via the pipe 14, and the pressure in the second air reservoir 13 is guided from the boat 136 to the second pressure chamber 123 via the pipe 15. Therefore, the piston 104 receives the pressure of the first air reservoir 9 and the second air reservoir 14 on the first pressure receiving surface 131 and the second pressure receiving surface 132 formed on the side surfaces of the piston heads 105 and 106, respectively.

As a result, the piston 104 has both pressure receiving surfaces 131 and 132
Only when the difference in the forces received by the coil springs 113 and 114 exceeds the preload of the coil springs 113 and 114 does the differential piston actuate due to the difference in pressure between the two. In the brake system configured as described above, the piston 104 is held at the neutral position by the spring devices 143, 144 while the pressures of the wet tank 4 and the air reservoirs 9, 13 are all equal to atmospheric pressure. cut valve 133, 13
All 4 are open.

Therefore, if the compressor 1 is driven in this state, air is forced to be sent to the air reservoirs 9 and 13 via the wet tank 4 and the safety device 100, and the pressure in each reservoir increases.
When the pressure in the exhaust tank 4 reaches a predetermined value, the air regulator 5 detects this and releases the suction valve of the compressor 1, so the compressor 1 becomes idle and the supply of air is stopped. This completes the brake operation criteria, and when the brake pedal 16 is depressed, the operating valve 18 opens, pressurized air is sent to the air boosters 21 and 27, hydraulic pressure is generated, and the wheel cylinders 23 and 31 operate. Braking takes place. If the pressure in the air reservoirs 9, 13 decreases as a result of brake operation, pressurized air is replenished from the wet tank 4, and as a result, if the pressure in the wet tank 4 decreases, the air regulator 5 returns the suction valve of the compressor 1 to its operating state. , the compressor 1 starts pumping air again, and the supply of pressurized air is completed. In this way, while both the front brake system and the rear brake system are normal, the pressures in the first and second air reservoirs 9, 13 are maintained at substantially constant heights that are equal to each other. However, if the front system air pipe is damaged,
The pressurized air in the first air reservoir 9 flows out from this damaged portion, and the pressure in the first air reservoir 9 decreases. In this case, the pressure in the wet tank 4 will naturally decrease, but since the air in the second air reservoir 13 is prevented from flowing backwards by the check valve 12, the pressure in the second air reservoir 13 will not decrease. , second air reservoir 9 and second air reservoir 13
There will be a difference in pressure between As a result, the first and second pressure chambers 122, 1 are in communication with both reservoirs 9, 13.
23 pressure difference is the coil. When the pre-compression of the springs 113 and 114 exceeds the set value, the piston 104 is moved to the lower pressure chamber 122, and the valve fixed to the piston head 106 is moved. 109 comes into contact with the stepped surface 128 of the main body 101. death,
The passage of pressurized air from boat 125 to boat 126 is blocked. Therefore, in this state, compressor 1
The pressurized air sent from As a result, the rear brake system can continue to operate normally. The above explanation has been made regarding the case where the front brake system has failed, but since the safety device 100 is constructed completely symmetrically, the same applies to the case where the rear brake system has failed. The brake system is automatically disconnected from the compressor 1, and the front brake system can continue to operate normally.

Furthermore, after repairing the brake system on the failed side, if the pressure air in the air reservoirs 9 and 13 is released and the pressure in both air reservoirs becomes atmospheric pressure, the first and second pressure chambers 122 of the safety device 100 , 123 both have atmospheric pressure,
The cut valve 13 is closed because the piston 104 is returned to the neutral position by the spring devices 143 and 144.
3 (or 134) is opened and the safety device 100 is restored to its inoperative state.

As described in detail above, in the safety device of this embodiment, only one safety device 100 with an extremely simple structure is installed, and if one of the two air brakes fails, both air reservoirs 9,
13 becomes equal to or higher than the value set by the coil springs 113 and 114, the pressure air passage to the air brake on the side that has failed will be automatically shut off, and this state will be maintained while the air brake on the normal side is closed. It keeps the air brake in a state where it can continue to operate, and has an excellent effect of further improving vehicle safety.

Furthermore, after the repair of the damaged part is completed, the safety device 100 can be returned to the non-operating state by simply releasing the pressurized air from the air reservoir, which makes the repair work easy. It is an effect. In addition, in the safety device 100 of this embodiment, since the set length of the coil springs 113, 114 can be accurately determined by the spring seats 115, 116, the coil springs 113, 114 can be arranged on both sides of the piston 104 without providing the spring seats 115, 116. Compared to the case where the piston 104 is held in the neutral position by the mutual compression force of the coil springs 113 and 114, the piston 104 can be placed in the neutral position more accurately, and therefore the lift amount of the cut valves 133 and 134 can be reduced. effective. Furthermore, compared to the embodiment device of the previous invention made by the inventors of the present invention, the spring seats 115, 116 are simply
The fact that the object of the present invention was achieved only by increasing the number of parts is an advantage unique to this embodiment. In the above embodiment, the piston was held at the neutral position with a small gap left between the spring seat and the piston head.
Conversely, one coil spring is prevented from expanding by the spring seat, but the other coil spring contacts the piston in a state where it can still expand slightly, thereby holding the piston in the neutral position. This state does not deviate from the spirit of the present invention.

It also compresses the compression spring to accurately regulate its length and generate a predetermined preload. The regulating means is not necessarily limited to the spring seats 115, 116, position-fixed spring seats 141, 142 formed on the plugs 102, 103, and main body stepped surfaces 111, 112 as in this embodiment. For example, as shown in FIG. 3, a spring seat 151, a spring seat 153 fixed in position formed on a plug 152, and a bolt 1 that prevents the coil spring 154 from elongating beyond a certain limit.
Needless to say, a means consisting of 55 may also be used. Furthermore, various improvements can be made without departing from the spirit of the present invention.
Needless to say, changes can be made.

As is clear from the above description, in the previous invention, the means for normally holding the differential piston in the safety device in the neutral position is a simple compression spring that is disposed in contact with the differential piston from both sides. In contrast, in the present invention, each of the compression springs is composed of a compression spring and a regulating means for compressing the compression spring to accurately regulate its length and generate a predetermined preload. This is a pair of spring devices that are arranged to face the piston from both sides.

From this, in the previous invention, even if there is a slight difference in the free length, spring constant, etc. of the springs arranged to face the operating piston from both sides, the differential piston can be accurately installed at the neutral position. However, the present invention has the advantage that the differential piston can be accurately placed in the neutral position. In addition, in the previous invention, the pressure difference between the first and second air reservoirs when the cut valve closes is accurately determined.
However, in the present invention, the differential piston moves and closes the cut valve only when the pressure difference between the first and second air reservoirs exceeds the value preset by the compression spring. Since the cut valve closes, it is possible to accurately set the pressure difference between the first and second air reservoirs when the cut valve closes. Furthermore, in the previous invention, the force that moves the differential piston (force based on the pressure difference) is balanced by the difference in elastic force between the two compression springs, etc., which is generated in advance by pre-compression of the compression spring, etc. It is unrelated to the preload that is applied, so in order to generate a predetermined force, it is necessary to increase the spring constant of the compression spring or the like or to increase the stroke of the differential piston. This has the disadvantage that the main body of the safety device becomes larger. In contrast, in the present invention, the preload that the compression spring has in advance balances the force that moves the actuating piston based on the pressure difference between the first and second air reservoirs, so a predetermined preload is generated. If the compression spring is compressed as much as possible, the spring constant of the compression spring and the stroke of the differential piston do not need to be so large, and the problems of the previous invention can be eliminated. As detailed above, the present invention relates to an improvement of the safety device in the two-system air brake system for vehicles that was previously invented by the inventors of the present invention. It is of great significance.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a two-system air brake system including an embodiment of the present invention, and FIG. 2 is an enlarged front sectional view showing the safety device in FIG. 1. FIG. 3 shows a compression spring regulating means different from that in FIG. 2. 1
: Compressor, 3, 8, 12: Check valve, 9: First air reservoir, 13: Second air reservoir, 16: Brake pedal, 18: Operating valve, 21, 27: Air booster, 23: Front wheel cylinder, 31:
Rear wheel cylinder, 100: Safety device, 101: Main body, 10 Te 4: Piston, 113, 114, 115: Coil spring, 115, 116, 151: Spring seat, 133: First cut valve, 134: Second cut valve, 155: Coil spring extension prevention bolt.

Claims (1)

[Claims] 1. Pressurized air generated by one compressor is divided into two parts and supplied to first and second air reservoirs through first and second check valves, respectively, and the first and second air reservoirs are used as pressure sources. In a two-system air brake system for a vehicle in which two systems of air brakes are operated independently of each other, two pressure-receiving systems facing each other are connected to a pressure air passage on the compressor side from the first and second check valves. a differential piston that receives the pressure of the first and second air reservoirs on its surface and is actuated by the difference between the two pressures; a compression spring; and a compression spring that compresses the compression spring to accurately regulate its length. and a regulating means for generating a predetermined preload, a pair of spring devices disposed facing the differential piston from both sides and always maintaining the working piston in a neutral position; When the pressure in the air reservoir becomes lower than the pressure in the second air reservoir by more than the pressure set by the precompression of the compression spring and the differential piston moves from the neutral position, the pressure air passage to the first air reservoir and the pressure in the second air reservoir becomes lower than the pressure in the first air reservoir by more than a pressure set by precompression of the compression spring, and the differential piston moves from the neutral position. At the time, a safety device including a second cut valve that cuts off the pressure air passage to the second air reservoir is inserted, and when one air brake system fails, the air brake system on the failed side is connected to the compressor. A safety device characterized by being separated from the