JPH0479864B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic brake operation device with a braking force holding device that can automatically maintain the brake in an activated state when a vehicle is stopped.

[Conventional technology]

Generally, in a vehicle, when the brake pedal is depressed, the brakes are activated and the vehicle is in a braking state, and when the brake pedal is released, the brake operation is released and the vehicle is in a non-braking state. Therefore, when the vehicle is temporarily stopped on a slope or the like, it is usually necessary to operate another braking device such as a handbrake.

Furthermore, when starting the vehicle again, it is necessary to release the handbrake and operate the accelerator or clutch, which requires skill.

In recent years, automatic brake operating devices that have a braking force retention device, which frees drivers from such complicated operating methods and allows them to perform safe and simple driving operations, have been developed. Even if the brake pedal is later released, the brake automatically maintains its braking state, and when the vehicle starts, the brake is automatically released in conjunction with the accelerator pedal depression, allowing for a smooth start. Automatic brake operating device with a braking force holding device (for example, Utility Model Application No. 56-83557
(see Japanese Patent Application Laid-open No. 11719/1983, etc.) was developed.

For example, Japanese Utility Model Application Publication No. 56-83557 discloses a hydraulic pressure holding device for an automobile brake as shown in FIG. This automobile brake fluid pressure holding device is designed to prevent fluid from being supplied to the brakes even if the brake pedal 10 is released when braking on an uphill road. A hydraulic pressure holding valve 17 that continues to hold the pressure is provided, and the hydraulic pressure holding valve is configured to release brake hydraulic pressure holding in conjunction with depression of the accelerator pedal 18.

However, this automobile brake hydraulic pressure holding device,
In other words, for automatic brake operating devices with braking force holding devices, in order to perform sophisticated and smooth control,
In addition, the reliability is not necessarily sufficient, and there are problems.

Furthermore, automatic brake operating devices having a braking force holding device have been developed as shown in FIGS. 5, 6A, and 6B.

FIG. 5 shows the piping system in the automatic brake operating device, in which the high pressure air accumulated in the main air tank 6 by the air pump is divided into two systems, the primary side and the secondary side, and is once accumulated in the sub air tank 5, and is then used to brake the air. Lines 12, 14 via valve 4
is supplied to the electromagnetically operated check valve 3.

High-pressure air passes through conduits 13 and 15 from the discharge side of the electromagnetically operated check valve 3 and is supplied to the air master 7 on the primary and secondary sides, respectively, to move a piston in the air master 7, that is, a brake actuator. The operation of the brake actuator operates the wheel cylinder and applies braking to the wheel.

The high pressure air in the main air tank 6 is released into the brake valve 4 only when the brake pedal 10 is depressed.
The discharge side of the brake valve 4 is configured to communicate with the atmosphere when the brake pedal 10 is released.

The electromagnetically operated check valve 3 is connected via a conduit 11,
High-pressure air is supplied separately, and in response to the opening and closing of the solenoid valve operated by a signal from the control device 9, the passage closing means provided in the solenoid-operated check valve 3 is operated by the high-pressure air. It is configured to block communication between the line 12 and the line 13, and between the line 14 and the line 15.

Next, the electromagnetically operated check valve 3 will be explained with reference to FIG. 6A and FIG. 6B. Since this electromagnetically operated check valve 3 is bilaterally symmetrical, only the right half, that is, the primary side will be described.

The electromagnetically operated check valve 3 has a cylinder 21,
A piston 22 is provided within the cylinder 21. A valve body 24 is attached to the tip of the piston 22 via a pin 23. A locking hole 50 for the pin 23 formed at the tip of the piston 22 and a pin locking hole 25 formed in the valve body 24 have a slightly larger diameter than the diameter of the pin 23. Therefore, the valve body 24 is attached to the piston 22 so as to be able to move slightly in the axial direction.

Further, the valve body 24 is always biased to the right in the figure by a spring 26 provided within the piston 22. A supply port 28 having a valve seat 27 is formed at the tip of the cylinder 21, and the supply port 28 is connected to the sub-air tank 5 via the pipe line 12 and the brake valve 4 (see FIG. 5). Also,
A discharge port 29 is formed at the tip of the cylinder 21, and the discharge port 29 is connected to the air master 7 via a conduit 13 (see FIG. 5).

A spring 31 is provided within a pressure chamber 30 formed by the cylinder 21 and the piston 22. Due to the action of the spring 31, the piston 22 and the valve body 2
4 is normally pressed in the direction away from the valve seat 27 (the position shown in FIG. 6A).

A solenoid valve 32 is attached to the center of the sill 21. The solenoid valve 32 has a solenoid 33 and a plunger 34, and the plunger 34 is connected to a rod 35 extending vertically downward. Below the rod 35, there are two
Two valve chambers 37 and 38 are provided, and two opposing valve bodies 39 are provided in the two valve chambers 37 and 38.
and 40 are arranged.

The two valve bodies 39 and 40 are connected to the rod 41.
The rods 35 and 41 are integrally connected coaxially via a connecting member 42. A spring 43 is disposed within the valve chamber 38, and due to the action of the spring 43, the plunger 34, the rod 35, the connecting member 42, the valve body 39,
Valve operating member 44 consisting of rod 41 and valve body 40
is normally biased upward, and the valve chamber 38 and passage 36 are closed off by a valve body 40.

The valve chamber 37 is provided in the cylinder 21 and is connected to the through hole 4.
5, the passage 36 communicates with an atmospheric chamber 46 at the rear of the piston 22, and the passage 36 furthermore communicates with a pressure chamber 48 at the rear of the piston 22 via an operating air passage 47. The valve chamber 38 is also connected to the high pressure air line 11 (see FIG. 5) via a supply port 49.

The operation of the electromagnetically operated check valve 3 described above is as follows. When the solenoid valve 32 is not energized, the valve operating member 44 is in the position shown in FIG. 6A. In that position, the valve body 40 causes the valve chamber 38 to
Communication between the valve chamber 37 and the passage 36 is cut off, and the atmospheric chamber 46 and the pressure chamber 48 at the rear of the piston 22 communicate with the atmosphere from the valve chamber 37 via the through hole 45 and the working air passage 47, respectively. Therefore, the piston 22 and the valve body 24 are urged to the most retracted position shown in FIG. 6A by the action of the spring 31.

Therefore, by depressing the brake pedal 10, the brake valve 4 is activated, and high pressure air flows from the pipe line 12 through the supply port 28 into the pressure chamber 30.
Furthermore, the air passes through the conduit 13 from the discharge port 29, flows into the air master 7, and operates the brake actuator. Braking action is produced by actuation of the brake actuator.

When the brake pedal 10 is released, the line 12 opens to the atmosphere as usual. When the vehicle stops, after a certain period of time, the control device 9 releases the solenoid valve 3.
A signal is emitted to turn on 2. Thereby,
The valve operating member 44 moves to the position shown in FIG.
The high pressure air flows into the pressure chamber 48 and the piston 22
is moved, and communication between the pipe line 12 and the pressure chamber 30 is cut off by the valve body 24. In this state, even if the pipe line 12 is communicated with the atmosphere, the pipe line 13 communicating with the brake actuator side is blocked from the atmosphere side by the valve body 24, so the inside of the pipe line 13 is maintained at a high pressure state. As a result, the brake will continue to operate or maintain its operating state.

Therefore, even if the brake pedal 10 is released while the vehicle is temporarily stopped on a slope, etc., the brake air pressure is maintained, so there is no risk that the vehicle will start moving by itself, and there is no need to necessarily pull the handbrake. do not have.

Further, when the vehicle is started by operating the accelerator or the clutch, the solenoid valve 32 is turned off in response to a command from the control device 9. When the solenoid valve 32 is turned off, the solenoid operated check valve 3 returns to the state shown in FIG.
Since 0 is a released state, the high pressure air in the pipe 13 on the brake actuator side is released to the atmosphere.
The brake operation is released and it is possible to start the vehicle. Therefore, it is no longer necessary to operate the accelerator or clutch while loosening the handbrake as in the past.

The operation of the electromagnetically operated check valve 3 is as described above, but the following measures are further taken. That is, normally, in a vehicle brake system, when the brake is operated, a pressure approximately equal to the pressure in the main air tank 6 is generated in the air master 7 and the pipes 12 and 13, and if this state is maintained for a long time,
This causes problems such as seizure on the brake friction surface and mechanical loss on the sealing surface.

To this end, in consideration of the need to maintain brake operation for a long period of time, there is a means to maintain the pressure in high-pressure parts such as the air master 7 at a value lower than the pressure required for brake operation when the vehicle is running. It is being In the case shown in FIG. 6A and FIG. 6B, F1 = [air pressure P1 in the pressure chamber 48 x effective pressure receiving area S1 of the piston on the pressure chamber 48 side], and F
2=[Air pressure P2 in the pressure chamber 30×effective pressure receiving area S2 of the piston on the pressure chamber 30 side+force f of the spring 31], then the difference F between F1 and F2, that is, F=
Due to F1-F2, while the piston 22 moves from the position shown in FIG. 6A to the position shown in FIG.
At the time when the communication between the brake actuator 3 and the pipe line 12 is cut off, the pressure on the pipe line 13 side is maintained at a pressure value that does not cause problems such as seizure on the brake actuator side. Therefore, the piston 22 and the valve body 24 function as a kind of pressure regulating valve or balance valve.

That is, in the electromagnetically operated check valve 3, the brake pedal 10 is depressed to stop the vehicle, and after a certain period of time has elapsed, the electromagnetic valve 3 is activated by a signal from the control device 9.
2 is turned on and high pressure air from the pipe line 11 flows into the pressure chamber 48, normally F1<
Since the piston 22 and the valve body 24 are designed to be F2, the piston 22 and the valve body 24 remain at the open position shown in FIG. As the pressure gradually decreases, the piston 22 moves to the right in the figure, and after a predetermined pressure drop, it finally reaches the position shown in FIG.
Communication with 2 is cut off.

[Problem that the invention seeks to solve]

However, in the piping structure of the automatic brake operating device described above, the pressure of the high pressure air supplied from the main air tank 6 to the supply port 49 of the electromagnetically operated check valve 3 causes the valve body 24 to move between the pipe line 12 and the pipe line 13.
The structure is such that the interior of the conduit 13 communicating with the brake actuator is maintained at a high pressure state. That is, the value of the air pressure maintained on the brake actuator side is determined by the magnitude of the pressure of high pressure air from the main air tank 6.

Therefore, if the pressure in the main air tank 6 drops even slightly below the specified pressure, the pressure maintained within the pipe 13 will also drop, and as a result, a constant braking force will not be obtained, which will solve the problem. have. For example, if the main air tank pressure is 8Kg/cm ²
(specified pressure), the pressure maintained in the conduit 13 communicating with the actuator side is 2Kg/ ^cm2.If the main air tank pressure reaches 7Kg/ ^cm2 , The pressure maintained within the conduit 13 is reduced to 1.75 Kg/cm ² .

Furthermore, if the brake pedal 10 is suddenly released while the solenoid valve 32 is on,
The pipe line 12 is instantly opened to the atmosphere,
As a result, the pressure chamber 30 and the pipe line 13 are also instantly opened to the atmosphere, and the pressure on the brake actuator side, that is, in the air master 7, decreases rapidly. Moreover, in order for the piston 22 and the valve body 24 to reach the line blocking position shown in FIG. 6B from the most retracted position shown in FIG. Yes, it takes a certain amount of time.

Therefore, when the brake pedal 10 is suddenly released, there is a relationship between the sudden pressure drop on the brake actuator side, that is, the pipe line 13 and the air master 7 side, and the time required for the valve body 24 to close. Therefore, at the time when the communication between the pipe line 13 and the pipe line 12 was cut off by the valve body 24, there was a possibility that the pressure in the pipe line 13 and the air master 7 would already drop below the predetermined pressure.

In particular, if the brake is pressed strongly when stopping the vehicle on a slope such as a slope, the conduit 13
In some cases, the pressure value on the brake actuator side may be higher, and in such a case, suddenly releasing the brake pedal 10 tends to cause an unnecessarily low pressure drop on the brake actuator side, and the so-called “brake” This poses a problem because the vehicle may start to move depending on the degree of inclination of the slope, which may cause a serious accident.

Therefore, it is conceivable to make the sliding resistance of the piston 22 extremely small, but in that case, the piston 22 will react sensitively to the air pressure in the main air tank 6. Pipeline 1 in case of pressure drop
A problem arises in that the phenomenon of a decrease in the pressure maintained within the range 3 is becoming more pronounced.

Therefore, an object of the present invention is to solve the above-mentioned problems, and the air pressure maintained in the conduit on the brake actuator side is the pressure of the air source, the piston of the electromagnetically operated check valve, and the valve. Provides an automatic brake operating device with a braking force holding device that can always maintain a predetermined pressure in the brake actuator side piping by creating a piping system that is not affected by body sliding resistance. It is to be.

[Means for solving problems]

In order to achieve the above object, the present invention is configured as follows. That is, the present invention provides a closing means for holding the air pressure supplied from an air source through the air valve and acting on the brake actuator upon operation of the brake valve, and a closing means for controlling the lower air pressure from the closing means or the air valve. A double check valve supplies the brake actuator, and the air valve has a discharge port to the closing means that opens when the air pressure from the brake valve is below a predetermined value and closes when the air pressure exceeds the predetermined value, and the brake valve. The present invention relates to an automatic brake operating device with a braking force holding device, which has a discharge port to the double check valve that is opened by air pressure from the double check valve.

Further, in this automatic brake operating device with a braking force holding device, the closing means is constituted by an electromagnetically operated check valve.

Further, in this automatic brake operation device with a braking force holding device, the closing means includes means for maintaining the air pressure on the brake actuator side at an air pressure lower than the brake operating pressure when the vehicle is running. It is something.

Further, in this automatic brake operating device with a braking force holding device, the closing means closes the piston and the valve body when the pressure supplied from the brake valve is at the predetermined value even if the pressure of the air source drops below a predetermined pressure. The ratio of the effective pressure-receiving area of the pressure chamber is set so as to achieve a full stroke.

Further, in this automatic brake operating device with a braking force holding device, the double check valve is
The air pressure on the closing means side is applied to the brake actuator in a state where the air pressure on the closing means side is not lower than the air pressure on the air valve side, and the air pressure on the closing means side is equal to the air pressure on the air valve side. The air pressure on the air valve side is applied to the brake actuator in a lower state.

Further, in this automatic brake operating device with a braking force holding device, the double check valve has a piston valve having a sliding resistance smaller than the sliding resistance of the piston of the closing means.

[Effect]

The automatic brake operating device with a braking force holding device according to the present invention is constructed as described above and operates as follows. That is, when the pressure of the air supplied from the brake valve to the air valve is below a predetermined value, the air valve functions to supply air to both the electromagnetically operated check valve and the double check valve. The air supplied to the electromagnetically operated check valve pushes open the piston and is supplied to the double check valve. However, since the piston of the electromagnetically operated check valve has sliding resistance, the double check valve works, causing the air supplied to the double check valve to flow through the pipe connecting the air valve and the double check valve. only is supplied to the air master.

When the air pressure supplied from the brake valve to the air valve exceeds a predetermined value, the air valve acts to cut off the supply of air to the electromagnetically operated check valve, so that air only flows toward the double check valve. become. At this time, air from the air valve is supplied to the air master by the action of the double check valve, but the supply of air from the electromagnetically operated check valve to the air master is cut off by the double check valve. .

Therefore, a predetermined value of air pressure is maintained in the conduit from the air valve to the double check valve via the electromagnetically operated check valve. When the brake valve is closed by releasing the brake pedal from this state, the air in the air master is transferred to the double check valve, the air valve,
The air flows to the brake valve and is released to the atmosphere, but when the pressure in the air master drops to a predetermined value, the double check valve shuts off the flow of air from the double check valve to the air valve. Ru.

At the same time, air is supplied to the electromagnetically operated check valve by the action of the double check valve, but at this time, since the piston of the electromagnetically operated check valve is in a full stroke state, Therefore, the flow of air toward the air valve side is blocked. As a result, a predetermined pressure is maintained on the air master side.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic brake operating device with a braking force holding device according to the present invention will be described in detail below with reference to the drawings. Here, the configuration of the electromagnetically operated check valve is the same as that explained with reference to Figures 6A and 6B, so the explanation will be made with reference to the same drawings. do.

FIG. 1 shows a piping system in an automatic brake operating device with a braking force holding device according to the present invention.
High pressure air accumulated in the main air tank 6 by the air pump is divided into two systems, a primary side and a secondary side, and is supplied to the brake valve 4 via the sub air tank 5. Brake valve 4 is connected to pipes 12 and 13
to one air master 7 through the pipe line 14,
15 to another air master 7. High-pressure air is separately supplied to the electromagnetically operated check valve 3 from a main air tank 6 via a conduit 11.

In addition to the piping system of the prior art described above, this automatic brake operating device with a braking force holding device has a piping line 1 connecting the brake valve 4 and the electromagnetically operated check valve 3.
2 and 14 are each provided with an air valve 1,
A double check valve 2 is provided in each of the pipes 13 and 15 connecting the electromagnetically operated check valve 3 and the air master 7.
Further, a conduit C connecting the air valve 1 and the double check valve 2 is provided.

The air pressure switch 8 is provided in the pipe A connecting the air valve 1 and the brake valve 4. When the brake pedal 10 is released, the air pressure switch 8 is turned on by the brake valve 4 communicating with the atmosphere. become a state. This signal is sent to the control device 9. The control device 9 sends a signal to turn on the solenoid valve 32 of the electromagnetically operated check valve 3 after a certain period of time after the vehicle has stopped.

Next, regarding the specific structure of the air valve 1,
This will be explained with reference to FIG. 2A and FIG. 2B. The air valve 1 includes a supply port 116 through which air is supplied from the brake valve 4 through a conduit A, a discharge port 117 which discharges air to a conduit B connected to the electromagnetically operated check valve 3, and a double check valve 2. It has a discharge port 118 that discharges air to a pipe line C connected to the pipe line C.
In addition, the air valve 1 includes a slidable piston valve 1.
19 is provided in a state where it is always biased to the right by a spring 120. A hollow hole 121 is formed in the rod 123 of the piston valve 119, and a valve port 122 is formed at the end of the hollow hole 121. The valve port 122 opens when a pressure of 2 kg/cm ² or less is acting on the piston valve 119 and connects pipe A and pipe B, but closes when a pressure exceeding 2 kg/cm ² acts on the pipe. The strength of the spring 120, the position of the valve port 122, etc. are set so as to block communication between the path A and the pipe B. Further, the discharge port 118 communicating with the pipe line C is always open regardless of the position of the piston valve 119.

Therefore, when the air pressure of the air supplied from the brake valve 4 is 2 kg/cm ² or less, the air supplied to the air valve 1 is as shown in FIG.
A part of the air from the supply port 116 flows into the pipe line B through the hollow hole 121 and the valve port 122, and the remaining air is discharged into the pipe line C. That is, the air supplied to the air valve 1 is supplied to both the electromagnetically operated check valve 3 and the double check valve 2.

Furthermore, when the air pressure of the air supplied from the brake valve 4 exceeds 2 kg/cm ² , the piston valve 119 moves to close the valve port 122 and close the air valve as shown in FIG. The air supplied to the double check valve 1 passes through the pipe A and is supplied only to the double check valve 2 from the pipe C.

Next, the specific structure of the double check valve 2 will be explained with reference to FIGS. 3A and 3B. The double check valve 2 has a supply port 125 on the pipe line D side connected to the electromagnetically operated check valve 3, a supply port 126 on the pipe line C side connected to the air valve 1,
Discharge port 12 on the pipe E side connected to the air master 7
It has 7.

A piston valve 129 is slidably provided in the cylinder 128 of the double check valve 2, so that the discharge port 127 communicates with the one of the pipes C and D, which has a higher air pressure. It is configured. That is, as shown in Fig. 3A, when the air pressure in conduit C is higher than that in conduit D, conduit C and conduit E communicate with each other, and the air pressure between conduit D and conduit E is Communication is cut off. Furthermore, as shown in Fig. 3B, when the air pressure in conduit D is higher than the air pressure in conduit C, conduit D and conduit E communicate with each other, and conduit C and conduit E are connected to each other. Communication is cut off. Moreover, the sliding resistance of the piston valve 129 is reduced by the piston 22 and the valve body 24 of the electromagnetically operated check valve 3.
The sliding resistance is designed to be sufficiently smaller than the sliding resistance of

Next, the operation of the automatic brake operating device with a braking force holding device according to the present invention will be explained.

First, when the electromagnetically operated check valve 3 is in the OFF state, the piston 22 and the valve body 24 are urged to the most retracted position shown in FIG. 6A by the action of the spring 31. Therefore, if the air pressure supplied from the brake valve 4 to the air valve 1 by depressing the brake pedal 10 is less than 2 kg/cm ² , the piston valve 119 of the air valve 1 is in the position shown in FIG. 2A. Also, the double check valve 2 is in the position shown in FIG. 3B. Therefore, the air from the main air tank 6 flows through the air valve 1 → electromagnetically operated check valve 3 → double check valve 2 → air master 7.
The braking action is produced by the braking action.

Furthermore, if the air pressure supplied from the brake valve 4 to the air valve 1 exceeds 2 kg/cm ² , the piston valve 119 of the air valve 1 is in the position shown in FIG. 3
It is located in the position shown in Figure A. Therefore, air from the main air tank 6 is supplied to the air valve 1 → double check valve 2 → air master 7, and similarly,
Braking action occurs. Therefore, in this case, even if the electromagnetic valve 32 of the electromagnetically operated check valve 3 fails, normal braking force can be generated as in the current system.

When the vehicle stops, the air pressure switch 8 detects this and the control device 9 issues a signal to turn on the solenoid valve 32 of the electromagnetically operated check valve 3. As a result, high-pressure air flows into the pressure chamber 48 from the main air tank 6 to move the piston 22, and the valve body 24 blocks communication between the pipe line 12 and the pipe line B and the pressure chamber 30. Here, when the pressure from the brake valve 4 is 2Kg/ ^cm2 , if the main air tank pressure is 5Kg/cm2 or ^more , the piston 22
The ratio of the effective pressure receiving area on the pressure chamber 48 side to the effective pressure receiving area of the pressure chamber 30 is set so that the valve body 24 can make a full stroke. That is, even if the main air tank pressure drops from 8 kg/cm ² (specified pressure) to 5 kg/cm ² , the piston 22 and the valve body 24 can make a full stroke.

When air is supplied from the brake valve 4 to the air valve 1, the air valve 1 will be in the state shown in Fig. 2A until the air pressure reaches 2 kg/cm ² , and the air will flow to both pipes B and C. flows. The air flowing into the pipe B flows into the electromagnetically operated check valve 3, pushes open the valve body 24, and flows into the pipe D.

However, at this time, the air pressure on the pipe line D side becomes smaller than the air pressure on the pipe line B side due to the sliding resistance of the valve body 24. That is, since the air pressure on the pipe D side is smaller than the air pressure on the pipe C side, the double check valve 2
operates, and the air from the brake valve 4 flows from the air valve 1 to the double check valve 2 to the air master 7. However, by setting the sliding resistance of the piston valve 129 of the double check valve 2 to be smaller than the sliding resistance of the valve body 24, the air pressure in the conduit C is higher than the air pressure in the conduit D. At the same time, the configuration is such that almost no pressure difference occurs between the conduit C and the conduit E.

Therefore, the output pressure of the brake valve 4 is directly output to the air master 7. That is,
The output pressure to the air master 7 does not decrease due to the sliding resistance of the valve body 24. Therefore, a sufficiently large braking force can be obtained.

When the air pressure supplied from the brake valve 4 to the air valve 1 becomes 2Kg/cm ² , the air valve 1 becomes
As shown in Figure 2B, valve port 1 that connects to pipe B
22, the supply of air to the electromagnetically operated check valve 3 is cut off, and air is supplied to the conduit C connected to the double check valve 2.

Therefore, the pressure in the pipe line C becomes greater than the pressure in the pipe line D, and the double check valve 2
In this case, as shown in FIG. 3A, the communication between the pipe line D and the pipe line E is cut off, and the pipe line C and the pipe E are communicated with each other. As a result, from the main air tank 6 to the brake valve 4
The air supplied through the air flows from the air valve 1 to the double check valve 2 to the air master 7.
Therefore, the electromagnetically operated check valve 3, piping B, and piping D
The air pressure inside is maintained at 2Kg/cm ² . Note that at this time, the piston 22 of the electromagnetically operated check valve 3 is fully stroked.

When the brake pedal 10 is released, the brake valve 4 is closed, so the air from the air master 7 is routed from pipe E to double check valve 2 to pipe C.
→ Air valve 1 → Pipe A → Flows to brake valve 4 and communicates with the atmosphere. When the air pressure in conduit E decreases to 2 kg/cm2 ^or less, the double check valve 2 shuts off the connection between conduit E and conduit C, and the connection between conduit E and conduit D becomes release. At the same time, the air valve 1 enters the state shown in FIG. exposed to the atmosphere. At this time, the electromagnetically operated check valve 3
Since the piston 22 is fully stroked, the connection between pipes B and D is cut off, and the air pressure in the air master 7, electromagnetically operated check valve 3, pipes E and D is 2 kg. / ^cm2 . Therefore, even if the brake pedal 10 is released while the vehicle is temporarily stopped on a slope or the like, the braking force is maintained, so there is no fear that the vehicle will start moving on its own.

When the accelerator pedal 10 is depressed, the control device 9 senses this and turns off the solenoid valve 32. When the electromagnetic valve 32 is turned off, the valve body 40 of the electromagnetically operated check valve 3 blocks communication between the valve chamber 38 and the passage 36, and the high pressure air in the pressure chamber 48 is released to the atmosphere. The piston 22 and the valve body 24 are connected to the spring 3
1 returns to the most retracted position shown in FIG. →Pipe D→Electromagnetically operated check valve 3→Pipe B→Air valve 1→Pipe A→Brake valve 4, and the brake valve 4 is released to the atmosphere. As a result, the braking force is released.

〔Effect of the invention〕

The automatic brake operating device with a braking force holding device according to the present invention is configured as described above, and has the following effects. In other words, in this automatic brake operation device with a braking force holding device, when the vehicle is temporarily stopped on a slope, etc., the amount of air pressure held on the brake actuator side is determined by the double check valve and the air valve. The electromagnetically operated check valve has the function of cutting off communication to prevent the air on the brake actuator side from being released from the brake valve to the atmosphere.

That is, the electromagnetically operated check valve serving as the closing means is configured such that the piston is always in a full stroke state when air pressure from the main air tank that exceeds a certain value acts on the piston. For this reason,
As long as the main air tank pressure does not drop abnormally, the air pressure held on the brake actuator side is always maintained at a predetermined value, regardless of the main air tank pressure.

Furthermore, in the electromagnetically operated check valve, the piston is always at full stroke when the valve is operated.
Conventionally, when the pressure held on the brake actuator side drops below a predetermined value until the communication is cut off by the piston due to the effect of sliding resistance of the piston, No inconvenience will occur. Therefore, a predetermined holding pressure can always be obtained without paying particular attention to how to release the brake pedal, making it extremely safe and easy to operate the brake.

Furthermore, in the piping system of the prior art automatic brake operating device, there is a pressure difference between the supply port side and the discharge port side of the electromagnetically operated check valve due to the sliding resistance of the valve body of the electromagnetically operated check valve. As a result, the air pressure sent out from the brake valve becomes smaller, resulting in the problem that a sufficiently large braking force cannot be obtained. In order to deal with this, it may be possible to reduce the sliding resistance of the valve body of the electromagnetically operated check valve, but in that case, there is another problem of vibration occurring when the electromagnetically operated check valve operates. will occur.

However, in the piping system of the automatic brake operating device with a braking force holding device according to the present invention,
Since the double check valve allows air to flow directly from the brake valve to the air master, no pressure difference occurs between the air master and the brake valve. Therefore, since the output pressure of the brake valve is directly output to the air master, a sufficiently large braking force can be obtained compared to the prior art.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the piping system of an automatic brake operating device with a braking force holding device according to the present invention, and FIG.
Figures A and 2B are cross-sectional views of air valves used in the automatic brake operating device with the braking force retention device shown in Figure 1, and Figures 3A and 3B are the automatic brakes with the braking force retention device shown in Figure 1. 4 is a schematic diagram showing the piping system of a conventional automatic operating device with a braking force retention device, and FIG. 5 is a cross-sectional view of a double check valve used in the operating device. A schematic diagram showing a piping system, and FIGS. 6A and 6B are sectional views showing an electromagnetically operated check valve in an automatic brake operating device with a braking force holding device. 1... Air valve, 2... Double check valve, 3... Solenoid operated check valve, 4... Brake valve, 6... Main air tank, 7... Air master (brake actuator), 8... Air pre Tsushiya switch, 9...control device, 10...brake valve, 11, 12, 13, 14, 15,
A, B, C, D, E... Pipe line, 22... Piston, 24... Valve body, 30, 48... Pressure chamber, 11
6... Supply port, 117, 118... Discharge port, 11
9... Piston valve, 125, 126... Supply port,
127...Discharge port, 128...Cylinder, 129
...Piston valve.

Claims (1)

[Scope of Claims] 1. Closing means for maintaining the air pressure supplied from an air source through the air valve and acting on the brake actuator upon operation of the brake valve, the air pressure from the closing means or the air valve being lower, whichever is lower. a double check valve that supplies air pressure to the brake actuator; and the air valve has a discharge port to the closing means that opens when the air pressure from the brake valve is below a predetermined value and closes when the air pressure exceeds the predetermined value; An automatic brake operating device with a braking force holding device comprising a discharge port to the double check valve that is opened by air pressure from the valve. 2. The automatic brake operating device with a braking force holding device according to claim 1, wherein the closing means is an electromagnetically operated check valve. 3. The braking force holding device according to claim 1, wherein the closing means includes means for maintaining the air pressure on the brake actuator side at a lower air pressure than the brake operating pressure when the vehicle is running. Automatic brake operation device with. 4. The closing means adjusts the ratio of the effective pressure receiving area of the pressure chamber so that the piston and the valve body are fully stroked when the pressure supplied from the brake valve is at the predetermined value even if the pressure of the air source drops below the predetermined pressure. An automatic brake operating device with a braking force holding device according to claim 1, wherein: 5. The double check valve causes the air pressure on the closing means side to act on the brake actuator in a state where the air pressure on the closing means side is not lower than the air pressure on the air valve side, so that the air pressure on the closing means side increases. The automatic brake operating device with a braking force holding device according to claim 1, wherein the air pressure on the air valve side is applied to the brake actuator in a state where the air pressure on the air valve side is lower than the air pressure on the air valve side. 6. The automatic brake operating device with a braking force holding device according to claim 1, wherein the double check valve has a piston valve with sliding resistance smaller than the sliding resistance of the piston of the closing means. .