JP7438979B2 - air supply circuit - Google Patents

Description

The present invention relates to an air supply circuit that supplies air to a brake mechanism of a vehicle.

The vehicle is equipped with a pneumatic brake system that includes a service brake mechanism (foot brake mechanism) and a parking brake mechanism. A pneumatic brake system includes an air supply circuit that supplies compressed air from a compressor and supplies dry compressed air to a parking brake mechanism. Recently, an air supply circuit that includes an electronic control device and is controlled by the electronic control device has been proposed (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2007-326516

However, the system described above does not take into consideration that the parking brake maintains an appropriate operating state when the electronic control unit loses power.
SUMMARY OF THE INVENTION An object of the present invention is to provide an air supply circuit that can maintain the operating state of a parking brake even if power to an electronic control device that controls the parking brake is lost.

An air supply circuit that achieves the above purpose has a relay valve between an air tank and a brake chamber for a parking brake, and is arranged in series between a supply channel that supplies air and an open circuit that releases air to the atmosphere. a normally closed first solenoid valve and a normally closed second solenoid valve; a control device that controls switching on and off, and transmits a pneumatic pressure signal between the first solenoid valve and the second solenoid valve to the relay valve as a control pressure signal for controlling the relay valve. Apply.

In this case, since the first solenoid valve and the second solenoid valve are normally closed, when the power to the control device that controls on/off of these solenoid valves is lost, the first solenoid valve and the second solenoid valve are closed. The air pressure immediately before the power loss during the period is maintained as the pressure of the air pressure signal between the first solenoid valve and the second solenoid valve. Therefore, the operation of the relay valve that inputs the air pressure signal as the control pressure signal is maintained. Thereby, even if the power to the control device that controls the parking brake is lost, the operating state of the parking brake can be maintained.

In one embodiment, the relay valve may include a release valve capable of releasing the control pressure signal applied to the relay valve to the atmosphere.
In this case, the parking brake, which is held in the released state by a pneumatic signal having the pressure of compressed air, can be activated by operating the release valve.

In one embodiment, an air pressure holding mechanism is provided between the first solenoid valve and the relay valve to prevent the air pressure from being transmitted from the first solenoid valve to the relay valve when the first solenoid valve is off. It is good that it is provided.

The parking brake is released when the air pressure increases and is activated when the air pressure decreases to atmospheric pressure. In this respect, in this case, when the first solenoid valve is off, there is no risk that the air pressure will increase and the parking brake will be released.

In one embodiment, the signal circuit is provided with a check valve that allows air to flow from the first solenoid valve disposed on the air tank side to the second solenoid valve disposed on the open circuit side. , the control pressure signal is an air pressure signal between the check valve and the second electromagnetic valve, and the first electromagnetic valve is configured to allow air to flow between the check valve and the check valve when the first electromagnetic valve is off. It may be a 3-port valve that opens.

In this case, the first solenoid valve is a 3-port valve, but because the check valve allows the air pressure on the second solenoid valve side to be maintained higher than on the first solenoid valve side, the Even if both the first solenoid valve and the second solenoid valve are turned off, the pressure of the pneumatic signal is maintained in the same way before and after the power loss.

Furthermore, even if compressed air leaks from the first solenoid valve when the first solenoid valve is off, the leaked compressed air is guided to the port of the first solenoid valve that is opened to the atmosphere by the sealing force of the check valve. . This prevents the air pressure on the second solenoid valve side from increasing, and prevents the parking brake, once activated, from being released unexpectedly. In other words, the air pressure holding mechanism is composed of a check valve and a second solenoid valve.

In one embodiment, the signal circuit includes a quick release valve, and when the pneumatic pressure signal has an air pressure equal to or higher than the operating pressure of the quick release valve, the pneumatic signal is passed through the quick release valve as the control pressure signal. atmospheric pressure is applied to the relay valve as the control pressure signal through the quick release valve when the pneumatic pressure signal has an air pressure less than the operating pressure of the quick release valve. That's fine.

In this case, when the first solenoid valve and the second solenoid valve are turned off due to loss of power to the control device, the control pressure signal to the relay valve is maintained in the state before the loss.
Furthermore, even if compressed air leaks from the first solenoid valve when the first solenoid valve is off, the air pressure signal between the first solenoid valve and the second solenoid valve must rise to the operating pressure of the quick release valve. For example, the control pressure signal is maintained at atmospheric pressure. Furthermore, even if air pressure below the operating pressure is slowly applied to the quick release valve, the control pressure signal will not rise to the operating pressure because it will leak into the open circuit. That is, the air pressure holding mechanism is composed of a quick release valve.

In one embodiment, the air supply circuit is connected to a brake chamber of the tractor and a trailer control valve, the signal circuit includes a third solenoid valve, and the air pressure signal is output to the trailer control valve. At the same time, compressed air may be applied to the relay valve via the third electromagnetic valve and regulated by the relay valve, and may be supplied to the brake chamber of the tractor.

In this case, the operating state of the parking brake of the tractor and the operating state of the parking brake of the trailer can be set to different states. For example, by blocking the pneumatic signal to the relay valve with the third solenoid valve, it is possible to release only the trailer's parking brake while keeping the tractor's parking brake operating, allowing inspection of only the tractor's parking brake. Be able to do it. Note that the parking brake of the trailer includes a parking brake that utilizes the main brake of the trailer.

In one embodiment, the third solenoid valve may be normally closed, and the control device may control switching on and off of the third solenoid valve.
In this case, since the third solenoid valve is normally closed, when the power to the control device that controls on/off of the solenoid valve is lost, even if air leaks from the first solenoid valve, the normally closed third solenoid valve This can prevent the pneumatic signal from being applied to the relay valve.

In one embodiment, the pneumatic signal may be output to the trailer control valve via a quick release valve.
In this case, the trailer control valve is supplied with a pneumatic signal via a quick release valve. When compressed air is not supplied to the trailer control valve, even if compressed air leaks from the first solenoid valve and a pressure lower than the operating pressure is applied to the pneumatic signal, the quick release valve opens to the atmosphere, so the tractor and The parking brake on the trailer is never released.

1 is a circuit diagram showing a schematic configuration of a first embodiment embodying an air supply circuit; FIG. FIG. 7 is a circuit diagram showing a schematic configuration of a second embodiment embodying an air supply circuit. FIG. 7 is a circuit diagram showing a schematic configuration of a third embodiment embodying an air supply circuit. FIG. 7 is a circuit diagram showing a schematic configuration of a fourth embodiment embodying an air supply circuit. FIG. 7 is a circuit diagram showing a schematic configuration of a fifth embodiment embodying an air supply circuit. FIG. 3 is a circuit diagram showing a schematic configuration of another embodiment embodying an air supply circuit. FIG. 3 is a circuit diagram showing a schematic configuration of another embodiment embodying an air supply circuit. FIG. 3 is a circuit diagram showing a schematic configuration of another embodiment embodying an air supply circuit. FIG. 3 is a circuit diagram showing a schematic configuration of another embodiment embodying an air supply circuit. FIG. 3 is a circuit diagram showing a schematic configuration of another embodiment embodying an air supply circuit.

(First embodiment)
FIG. 1 shows a first embodiment in which an air supply circuit 10 is applied to a parking brake mechanism of a tractor (not shown) as a vehicle. The parking brake mechanism uses compressed dry air as its driving source. A tractor is a vehicle to which a trailer can be attached. That is, a trailer can be connected to the tractor.

Generally, a tractor is provided with a service brake mechanism and a parking brake mechanism. The service brake is activated when air is supplied to the service brake mechanism, and the service brake is released (deactivated) when air is discharged from the service brake mechanism. When air is supplied to the parking brake mechanism, the parking brake is released, and when air is discharged from the parking brake mechanism, the parking brake is activated. The air supply circuit 10 is a circuit applied to a parking brake mechanism.

As shown in FIG. 1, the air supply circuit 10 adjusts the supplied compressed air and supplies the adjusted compressed air to a brake chamber of a tractor or a control valve of a trailer.
The tractor includes an air tank 13 and an air supply circuit 10 that store dry and purified air supplied from a compressor (not shown) driven by an engine (not shown). The air supply circuit 10 adjusts the compressed air supplied from the air tank 13 through the 13th port P13, and supplies the adjusted compressed air to the 21st port P21 and the 22nd port P22, thereby providing the 21st port P21 and the 22nd port P22 with the adjusted compressed air. The parking brake of the tractor is released or activated via the 22nd port P22.

A trailer control valve (TCV) is connected to the 31st port P31 of the air supply circuit 10. The trailer control valve releases or applies the trailer's parking brake by controlling the supply and exhaust of air to and from the trailer's pneumatic circuit. Note that the trailer parking brake here uses the main brake of the trailer, but for convenience of explanation, it will be hereinafter referred to as the trailer parking brake.

The configuration of the air supply circuit 10 will be explained.
In the air supply circuit 10, a plurality of wires E61 to E66 are connected to an ECU 21 as a control device. Note that explanations of other wiring will be omitted. The ECU 21 includes a calculation section, a volatile storage section, and a nonvolatile storage section, and gives command values to the air supply circuit according to a program stored in the nonvolatile storage section. The ECU 21 is connected to other control devices such as a vehicle ECU via a wiring E61, which is a communication line such as an in-vehicle LAN, so that vehicle information can be exchanged with these control devices.

The air supply circuit 10 mainly includes a supply flow path 50 that supplies compressed air from the air tank 13 to each port P21, P22, and a signal circuit 60 that mainly transmits an air pressure signal to adjust the air pressure supplied to the parking brake. It is equipped with

The supply flow path 50 is a flow path from the 13th port P13 to the 21st port P21 and the 22nd port P22, and branches into the relay valve 40 and the 21st port P21 and the 22nd port P22 in the middle of the flow path. A branch part. The first flow path 51 is from the 13th port P13 to the input of the relay valve 40, the second flow path 52 is from the output of the relay valve 40 to the branch, and the third flow is from the branch to the 21st port P21. The passage 53 is the fourth passage 53, and the fourth passage 54 is from the branching part to the 22nd port P22.

The signal circuit 60 transmits a pneumatic signal for adjusting the strength of the parking brake to the relay valve 40 and to the trailer control valve via the 31st port P31. Relay valve 40 releases or applies the parking brake of the tractor based on the pneumatic signal. The trailer control valve releases or applies the parking brake of the tractor based on the pneumatic signal.

The signal circuit 60 is a circuit from the 13th port P13 to the open circuit 39, and includes, in order from the circuit upstream, a first solenoid valve 41, a check valve 45, a third solenoid valve 43, and a second solenoid valve 42. . The circuit from the 13th port P13 to the input of the first solenoid valve 41 is the first circuit 61, the circuit from the output of the first solenoid valve 41 to the input of the check valve 45 is the second circuit 62, and the circuit from the check valve 45 to the third solenoid A third circuit 63 extends from the third solenoid valve 43 to the second solenoid valve 42 , and a fourth circuit 64 extends from the third solenoid valve 43 to the second solenoid valve 42 , and the outlet of the second solenoid valve 42 is connected to the open circuit 39 . The third circuit 63 is branched and further connected to a sixth circuit 66 connected to the 31st port P31 and a signal air pressure sensor (PU) 47 that detects air pressure. The fourth circuit 64 is branched and further connected to a fifth circuit 65 to which the relay valve 40 is connected. Furthermore, the fifth circuit 65 is connected to the release valve 101 via the 101st port P101. The open circuit 39 communicates with an outlet 49 that is open to the atmosphere. The release valve 101 may be a manual valve so that it can be operated even when the power to the ECU 21 is lost, or a valve that can be operated from another control device such as the vehicle ECU.

The check valve 45 allows compressed air to flow in the direction (permissible direction) from the second circuit 62 to the third circuit 63. On the other hand, the check valve 45 prohibits the supply of compressed air in the direction from the third circuit to the second circuit 62 (prohibited direction). Note that the check valve 45 has a sealing force that does not permit air flow below a predetermined pressure even if the flow is in the permissible direction.

The ECU 21 is connected to the first electromagnetic valve 41 via wiring E62, to the third electromagnetic valve 43 via wiring E64, and to the second electromagnetic valve 42 via E65. Further, the ECU 21 is connected to a signal air pressure sensor 47 via a wiring E63, and to a supply air pressure sensor 48 via a wiring E66. The ECU 21 can obtain the air pressure of the signal circuit 60 from the signal air pressure sensor 47 and the air pressure of the supply flow path 50 from the supply air pressure sensor 48 .

The first solenoid valve 41, the second solenoid valve 42, and the third solenoid valve 43 are each two-position solenoid valves whose operation is switched by turning on and off the power based on the control of the ECU 21. In the following, a state in which the power is turned off will be referred to as "off" and a state in which the power is turned on will be referred to as "on".

The first solenoid valve 41 is a normally closed three-port, two-position solenoid valve, and its on/off state is controlled via the wiring E62. The first electromagnetic valve 41 is placed in the sealed position shown in FIG. 1 when turned off, and placed in the communicating position when turned on. In the sealed position, the first electromagnetic valve 41 blocks communication between the first circuit 61 and the second circuit 62 and allows the second circuit 62 to communicate with the open circuit 39 . In the communication position, the first solenoid valve 41 allows the first circuit 61 and the second circuit 62 to communicate with each other, and blocks communication between the second circuit 62 and the open circuit 39 .

The second solenoid valve 42 is a normally closed two-port, two-position solenoid valve, and its on/off state is controlled via the wiring E65. The second solenoid valve 42 is off and placed in the sealing position shown in FIG. 1, and on and placed in the communicating position. The second electromagnetic valve 42 blocks communication between the fourth circuit 64 and the open circuit 39 in the sealed position, and allows the fourth circuit 64 and the open circuit 39 to communicate in the communicating position.

The third solenoid valve 43 is a solenoid valve for releasing only the parking brake of the trailer for inspection. The third solenoid valve 43 is normally kept off and turned on during inspection. The third solenoid valve 43 is a normally open two-port, two-position solenoid valve, and its on/off state is controlled via the wiring E64. The third solenoid valve 43 is disposed in the communication position shown in FIG. 1 when it is off, and is disposed in the sealing position when it is on. The third electromagnetic valve 43 blocks communication between the third circuit 63 and the fourth circuit 64 in the sealing position, and allows the third circuit 63 and the fourth circuit 64 to communicate with each other in the communication position.

The operation of such air supply circuit 10 will be explained.
First, when changing the parking brake from an activated state (on state) to a released state (off state), the ECU 21 turns on the first solenoid valve 41 and turns off the third solenoid valve 43 and the second solenoid valve 42. As a result, the second circuit 62 , the third circuit 63 , and the fourth circuit 64 hold the air pressure signal of the air pressure based on the compressed air from the air tank 13 , and the air pressure signal of the air pressure of the fourth circuit 64 is held via the fifth circuit 65 . The signal activates relay valve 40. The relay valve 40 supplies compressed air from the air tank 13 to each brake chamber via the second flow path 52, the third flow path 53, and the fourth flow path 54. The ECU 21 detects the air pressure in the third circuit 63 using the signal air pressure sensor 47, and detects the air pressure in the third flow path 53 and the fourth flow path 54 using the supply air pressure sensor 48. When the detected pressures of the signal air pressure sensor 47 and the supply air pressure sensor 48 reach their respective target pressures, the ECU 21 turns off the first electromagnetic valve 41 and turns on the second electromagnetic valve 42 to close the second to fifth circuits 62. - Set the pressure of the air pressure signal of 65 to atmospheric pressure. On the other hand, when the detected pressure of either the signal air pressure sensor 47 or the supply air pressure sensor 48 becomes lower than the corresponding target pressure, the ECU 21 turns off the second solenoid valve 42 and then turns on the first solenoid valve 41 to increase the air pressure. The pressure of the signal is the compressed air from the air tank 13. As a result, the air pressure in the second flow path 52, the third flow path 53, and the fourth flow path 54 is adjusted and maintained at the target pressure, and compressed air at a predetermined pressure is supplied to the brake chamber, and the parking brake of the tractor is is canceled. Further, compressed air at a target pressure is supplied to the trailer control valve, and the parking brake of the trailer is released.

Note that the ECU 21 may control ON/OFF of the first electromagnetic valve 41 and the second electromagnetic valve 42 based on the pressure detected by either the signal air pressure sensor 47 or the supply air pressure sensor 48. Further, the ECU 21 may learn from the signal air pressure sensor 47 the air pressure required by the signal circuit 60 in order to make the air pressure detected by the supply air pressure sensor 48 a target air pressure.

Next, when changing the parking brake from the released state to the activated state, the ECU 21 turns off the first solenoid valve 41 and the third solenoid valve 43, and turns on the second solenoid valve 42. Thereby, the third circuit 63 and the fourth circuit 64 are connected to the open circuit 39, and the pressure of the air pressure signal is maintained at atmospheric pressure. The atmospheric air pressure signal disables the relay valve 40 and no compressed air is supplied to the brake chamber from the second flow path 52, third flow path 53, and fourth flow path 54, so that the brake chamber applies the parking brake. Activate. The ECU 21 detects the air pressure in the third circuit 63 using the signal air pressure sensor 47, and detects the air pressure in the third flow path 53 and the fourth flow path 54 using the supply air pressure sensor 48. The ECU 21 confirms that the detected pressures of the signal air pressure sensor 47 and the supply air pressure sensor 48 are each atmospheric pressure. The ECU 21 may turn off the second electromagnetic valve 42 when the detected pressure becomes atmospheric pressure. At this time, when the detected pressure of either the signal air pressure sensor 47 or the supply air pressure sensor 48 is no longer atmospheric pressure, the ECU 21 turns on the second electromagnetic valve 42 so that the detected pressure becomes atmospheric pressure. Thereby, the air pressure in the third flow path 53 and the fourth flow path 54 is maintained at atmospheric pressure. Therefore, the brake chamber is maintained at atmospheric pressure and the parking brake of the tractor is operated. Further, the air pressure of the trailer control valve is set to atmospheric pressure, and the parking brake of the trailer is operated.

The air supply circuit 10 can also release only the parking brake of the trailer for inspection. When performing an inspection, the ECU 21 first turns on the second electromagnetic valve 42 and turns off the third electromagnetic valve 43 to activate (on) the parking brake of the tractor and trailer. Next, the third solenoid valve 43 is turned on to maintain the air pressure in the fourth circuit 64, thereby maintaining the operating state of the parking brake of the tractor. Subsequently, when the first solenoid valve 41 is turned on, compressed air is supplied to the port P31 via the third circuit 63 and the sixth circuit 66, and the parking brake of the trailer is released. Even if power is lost during an inspection, only the parking brake of the tractor can be kept in operation. As a result, the parking brake of the trailer is released, and only the parking brake of the tractor can be inspected. This test is to see if the tractor to which the trailer is connected can be kept stopped on a slope with a 12% gradient using only the tractor's parking brake, with the trailer's parking brake released.

The operation of this embodiment will be explained.
By the way, the ECU 21 may lose power due to a disconnection or the like. At this time, it is necessary to maintain the released state or the activated state at the time of power loss so that the operating state of the parking brake does not differ from the operation performed by the driver immediately before the power loss. That is, it is necessary to prevent the parking brake from switching from a released state to an activated state or from an activated state to a released state due to power loss of the ECU 21. In this regard, according to the present embodiment, even if the ECU 21 loses power due to a disconnection or the like, the operating state of the parking brake is maintained in the operating state at the time of power loss. In the following, it is assumed that the inspection is not for the parking brake of the trailer, that the normally open third solenoid valve 43 is open, and that the third circuit 63 and the fourth circuit 64 are in communication.

First, a case will be described in which the power to the ECU 21 is lost while the parking brake is in the operating state.
Immediately before power loss, the first solenoid valve 41 is turned off, the second solenoid valve 42 is turned on or turned off after being opened to the atmosphere, and the second circuit 62, third circuit 63, and fourth circuit 64 are all opened to the atmosphere. ing. Due to this power loss, the first solenoid valve 41 and the second solenoid valve 42 which are normally closed are both turned off and closed, and the third circuit 63 sandwiched between the check valve 45 and the second solenoid valve 42 The atmospheric pressure immediately before the power loss is maintained in the fourth circuit 64. Therefore, the relay valve 40, which receives the pneumatic signal from the fourth circuit 64, remains closed to maintain the operating state of the parking brake of the tractor. Further, the trailer control valve receiving the pneumatic signal from the third circuit 63 maintains the operating state of the parking brake of the trailer.

By the way, even if the first electromagnetic valve 41 is turned off, compressed air is constantly supplied from the air tank 13, so there is a risk that the compressed air will leak to the check valve 45 side due to deterioration of the valve or the like. At this time, the first solenoid valve 41 connects the second circuit 62 on the check valve 45 side to the open circuit 39, so the leaked compressed air is released to the atmosphere and the pressure on the check valve 45 side is increased. Maintain atmospheric pressure. Furthermore, the check valve 45 maintains its closed state because it will not open unless a predetermined valve opening pressure is applied. In other words, the compressed air leaking from the first solenoid valve 41 increases the air pressure in the third circuit 63 and the fourth circuit 64 via the check valve 45, opens the relay valve 40, and releases the operating parking brake. There is no fear. Therefore, the pressures of the air pressure signals of the third circuit 63 and the fourth circuit 64 are maintained at the same atmospheric pressure as immediately before the power loss even after the power loss, and therefore are stable and highly reliable.

Next, a case will be described in which the power to the ECU 21 is lost while the parking brake is in the released state.
Since the parking brake is in the released state, immediately before the power is lost, the first solenoid valve 41 is turned on or turned off after pressure regulation, the second solenoid valve 42 is turned off, and the third circuit 63 and the fourth circuit 64 are in the predetermined state. maintained at pneumatic pressure. When the first solenoid valve 41 and the second solenoid valve 42 which are normally closed are both turned off and closed due to power loss, the third circuit 63 sandwiched between the check valve 45 and the second solenoid valve 42 The predetermined air pressure immediately before the power loss is maintained in the fourth circuit 64. Therefore, the relay valve 40, which receives a pneumatic pressure signal of a predetermined pneumatic pressure from the fourth circuit 64, maintains the open state to maintain the released state of the parking brake of the tractor. Further, the trailer control valve receiving the pneumatic signal from the third circuit 63 maintains the released state of the parking brake of the trailer.

By the way, when the first solenoid valve 41 is turned off, it connects the second circuit 62 on the check valve 45 side to the open circuit 39, but since the check valve 45 does not allow air to flow from the third circuit 63 to the second circuit 62, The air pressure in the third circuit 63 and the fourth circuit 64 will not decrease, and there is no fear that the parking brake will operate while it is being released. Therefore, the air pressure signals of the third circuit 63 and the fourth circuit 64 are maintained at the same air pressure as immediately before the power loss even after the power loss, and therefore are stable and highly reliable.

Note that when the parking brake is in the released state, the released state is maintained, but the parking brake can also be operated after moving the vehicle to an appropriate position. That is, the release valve 101 is connected to the fifth circuit 65 branching from the fourth circuit 64 together with the relay valve 40 . If the parking brake is in the released state when the power is lost to the ECU 21, the parking brake will be maintained in the released state even after the power is lost, but when the release valve 101 is opened, the fifth circuit 65, the fourth circuit 64, and the third circuit 63 are released. Open to atmospheric pressure. Thereby, the parking brake of the tractor can be switched from the released state to the activated state, and the parking brake of the trailer can be switched from the released state to the activated state, and these activated states are maintained.

According to this embodiment, the following effects can be obtained.
(1) Since the first solenoid valve 41 and the second solenoid valve 42 are normally closed, when the power of the ECU 21 that controls on/off of these solenoid valves is lost, the first solenoid valve 41 and the second solenoid valve The air pressure between the first electromagnetic valve 41 and the second electromagnetic valve 42 immediately before the power loss is maintained as the pressure of the air pressure signal between the first electromagnetic valve 41 and the second electromagnetic valve 42. Therefore, the operation of the relay valve 40 which inputs the air pressure signal of the fourth circuit 64 as the control pressure signal of the fifth circuit 65 is maintained. Thereby, even if the power to the ECU 21 that controls the parking brake is lost, the operating state of the parking brake can be maintained.

(2) The parking brake, which is held in the released state by a pneumatic signal having the pressure of compressed air, can be activated by operating the release valve 101.
(3) The parking brake is released when the air pressure increases, and operates when the air pressure reaches atmospheric pressure. Since the first solenoid valve 41 is a 3-port valve and the check valve 45 is provided downstream of the first solenoid valve 41, when the first solenoid valve 41 is off, there is a risk that the air pressure will increase and the parking brake will be released. There is no.

(4) Although the first solenoid valve 41 is a three-port valve, the sealing force of the check valve 45 allows the air pressure on the second solenoid valve 42 side to be maintained higher than on the first solenoid valve 41 side. Therefore, even if both the first solenoid valve 41 and the second solenoid valve 42 are turned off due to power loss of the ECU 21, the pressure of the air pressure signal is maintained in the same way before and after the power loss. That is, the air pressure holding mechanism is composed of the check valve 45 and the second solenoid valve 42.

Furthermore, even if compressed air leaks from the first solenoid valve 41 when the first solenoid valve 41 is off, the leaked compressed air is guided by the check valve 45 to the port of the first solenoid valve 41 that is opened to the atmosphere. Ru. This prevents the air pressure on the second solenoid valve 42 side from increasing, and prevents the parking brake, once activated, from being released unexpectedly.

(5) By operating the third solenoid valve 43, the operating state of the parking brake of the tractor and the operating state of the parking brake of the trailer can be set to different states. For example, by blocking the pneumatic signal to the relay valve 40 with the third solenoid valve 43, it is possible to release only the parking brake of the trailer while keeping the parking brake of the tractor operating. Tests can be performed. Specifically, after operating the parking brakes of the tractor and trailer, the third solenoid valve 43 is turned on to enable compressed air to be supplied to the trailer control valve and to disable supply of compressed air to the relay valve 40. can do. Thereby, the parking brake of the trailer can be released while the parking brake of the tractor remains activated.

(Second embodiment)
A second embodiment embodying an air supply circuit will be described with reference to FIG. 2. This embodiment is different from the signal circuit 60 of the first embodiment in a signal circuit 60A. Note that, for convenience of explanation, the same components as in the first embodiment are given the same reference numerals, and detailed explanations are omitted.

As shown in FIG. 2, in this embodiment, similarly to the first embodiment, the air supply circuit 10 includes a supply flow path 50 and a signal circuit 60A that transmits an air pressure signal.
The signal circuit 60A includes a first solenoid valve 41A between the first circuit 61 and the third circuit 63. The first solenoid valve 41A is a normally closed two-port, two-position solenoid valve, and its on/off state is controlled by turning on and off the power from the wiring E62. The first electromagnetic valve 41A is placed in the sealed position shown in FIG. 2 when turned off, and placed in the communication position when turned on. The first electromagnetic valve 41A disconnects the first circuit 61 and the third circuit 63 in the sealed position, and connects the first circuit 61 and the third circuit 63 in the communicating position. A branch circuit 63A of the third circuit 63 is connected to the open circuit 39 and the sixth circuit 66 via the quick release valve 46.

The quick release valve 46 is connected to the branch circuit 63A, the open circuit 39, and the sixth circuit 66. The quick release valve 46 connects the open circuit 39 to the sixth circuit 66 when the air pressure in the branch circuit 63A is less than a predetermined pressure. On the other hand, the quick release valve 46 connects the third circuit 63 to the sixth circuit 66 via the branch circuit 63A when the air pressure in the branch circuit 63A is equal to or higher than a predetermined pressure.

A case in which the power to the ECU 21 is lost in this embodiment will be described.
First, a case will be described in which the power to the ECU 21 is lost while the parking brake is in the operating state.

Immediately before power loss, the first solenoid valve 41A is turned off, the second solenoid valve 42 is turned on or turned off after being opened to the atmosphere, and the third circuit 63 and the fourth circuit 64 are opened to the atmosphere. Due to this power loss, both the first solenoid valve 41A and the second solenoid valve 42 are turned off and closed, and the third circuit 63 and the fourth circuit sandwiched between the first solenoid valve 41A and the second solenoid valve 42 64, the atmospheric pressure immediately before the power loss is maintained. Therefore, the relay valve 40, which receives the pneumatic signal from the fourth circuit 64 via the fifth circuit 65, remains closed to maintain the operating state of the parking brake of the tractor. Further, when the pressure in the branch circuit 63A is less than a predetermined pressure, the quick release valve 46 connects the sixth circuit 66 to the open circuit 39. Therefore, the trailer control valve receiving atmospheric pressure from the sixth circuit 66 maintains the operating state of the parking brake of the trailer.

By the way, when the parking brake is operating, the first solenoid valve 41A is constantly supplied with compressed air from the air tank 13 even if it is off, so compressed air may not flow into the third circuit 63 due to valve deterioration or the like. There is a risk of leakage. At this time, the quick release valve 46 releases air at a pressure lower than a predetermined pressure applied from the branch circuit 63A lower than the operating pressure to the open circuit 39. Therefore, even if compressed air leaks from the first solenoid valve 41A, the pressure in the third circuit 63 can be maintained at a pressure lower than the operating pressure of the quick release valve 46. In addition, since the operating pressure of the quick release valve 46 is lower than that of the relay valve 40, there is no risk that leaked compressed air will increase the air pressure in the third circuit 63 and the fourth circuit 64, and the parking brake during operation There is no risk that it will be lifted. Therefore, even after the power loss, the air pressure signals of the third circuit 63 and the fourth circuit 64 are maintained at the same atmospheric pressure as immediately before the power loss, and are stable and highly reliable.

Next, a case will be described in which the power to the ECU 21 is lost while the parking brake is in the released state.
Immediately before the power is lost, the first solenoid valve 41A is turned on or turned off after adjusting the pressure, the second solenoid valve 42 is turned off, and the third circuit 63 and the fourth circuit 64 are maintained at a predetermined air pressure. Due to this power loss, both the first solenoid valve 41A and the second solenoid valve 42 are turned off and closed, and the third circuit 63 and the fourth circuit sandwiched between the first solenoid valve 41A and the second solenoid valve 42 At 64, the air pressure immediately before the power loss is maintained. At this time, communication between the branch circuit 63A and the sixth circuit 66 by the quick release valve 46 is also maintained by the pneumatic signal of the branch circuit 63A. Therefore, the relay valve 40, which receives the pneumatic signal from the fourth circuit 64 via the fifth circuit 65, remains open to maintain the released state of the parking brake of the tractor. Further, the quick release valve 46 in which the pressure in the branch circuit 63A is equal to or higher than a predetermined pressure connects the branch circuit 63A to the sixth circuit 66. Therefore, the trailer control valve receiving the pneumatic signal from the branch circuit 63A maintains the released state of the parking brake of the trailer.

By the way, even if the first electromagnetic valve 41A is off, compressed air is constantly supplied from the air tank 13, so there is a risk that compressed air may leak into the third circuit 63 due to deterioration of the valve or the like. However, even if compressed air leaks into the third circuit 63, the air pressure in the third circuit 63 and fourth circuit 64 to which compressed air was originally supplied is maintained, and the parking brake is maintained in a released state. . In other words, there is no risk that the air pressure in the third circuit 63 and the fourth circuit 64 will decrease and the parking brake that is being released will operate. Therefore, even after the power loss, the air pressure signals of the third circuit 63 and the fourth circuit 64 are maintained at the same air pressure as immediately before the power loss, and are stable and highly reliable.

Note that, similarly to the first embodiment, by opening the release valve 101, the fifth circuit 65, the fourth circuit 64, and the third circuit 63 are opened to atmospheric pressure. Thereby, the parking brake of the tractor can be switched from the released state to the activated state, and the parking brake of the trailer can be switched from the released state to the activated state, and these activated states can be maintained.

According to this embodiment, in addition to the effects (1) to (3) described in the first embodiment, the following effects can be obtained.
(6) Since the air pressure signal is applied to the relay valve 40 as a control pressure signal via the quick release valve 46, when the first solenoid valve 41A and the second solenoid valve 42 are turned off due to power loss of the ECU 21, the relay valve The control pressure signal to 40 is maintained in the state before loss.

Furthermore, when the first solenoid valve 41A is off, even if compressed air leaks from the first solenoid valve 41A, the air pressure signal between the first solenoid valve 41A and the second solenoid valve 42 will actuate the quick release valve 46. If the pressure does not rise to atmospheric pressure, the control pressure signal is maintained at atmospheric pressure. Furthermore, even if air pressure lower than the operating pressure is slowly applied to the quick release valve 46, the control pressure signal will not rise to the operating pressure because it will leak to the open circuit 39.

(7) A pneumatic signal is supplied to the trailer control valve via the quick release valve 46. When compressed air is not supplied to the trailer control valve, even if compressed air leaks from the first solenoid valve 41A and a pressure lower than the operating pressure is applied to the air pressure signal, the quick release valve 46 opens to the atmosphere. The parking brake of the tractor and trailer is never released.

(Third embodiment)
A third embodiment embodying an air supply circuit will be described with reference to FIG. 3. This embodiment is for a tractor (motorcycle) when not towing a trailer, and differs from the first embodiment mainly in that the signal circuit 60B does not include the third solenoid valve 43.

As shown in FIG. 3, in this embodiment, similarly to the first embodiment, the air supply circuit 10 includes a supply flow path 50 and a signal circuit 60B that transmits an air pressure signal.
The signal circuit 60B includes a first solenoid valve 41, a check valve 45, and a second solenoid valve 42 in this order between the thirteenth port P13 and the open circuit 39. The first circuit 61 is from the 13th port P13 to the first solenoid valve 41, the second circuit 62 is from the first solenoid valve 41 to the check valve 45, and the fourth circuit is from the check valve 45 to the second solenoid valve 42. A circuit 64 in which the second solenoid valve 42 is connected to the open circuit 39 . In this embodiment, the third circuit 63 in the first embodiment is not provided. A signal air pressure sensor 47 that detects air pressure is connected to the fourth circuit 64. The fourth circuit 64 is branched from the fifth circuit 65 . The fifth circuit 65 is connected to the relay valve 40 and also to the release valve 101 via the 101st port P101.

The air supply circuit 10 of this embodiment does not have a mechanism for releasing only the parking brake of the trailer for inspection, which the first embodiment had. Therefore, the operation of the air supply circuit 10 is the same as the operation when the third electromagnetic valve 43 is off and no inspection is performed in the first embodiment, so a description thereof will be omitted.

According to this embodiment, in addition to the effects (1) to (4) described in the first embodiment, the following effects can be obtained.
(8) In a tractor (motorcycle) that does not tow a trailer, the structure of the air supply circuit 10 can be made simpler than in a tractor that tows a trailer.

(Fourth embodiment)
A fourth embodiment embodying an air supply circuit will be described with reference to FIG. 4. This embodiment differs from the second embodiment in that it is for a tractor (motorcycle) when not towing a trailer.

As shown in FIG. 4, in this embodiment, similarly to the first embodiment, the air supply circuit 10 includes a supply flow path 50 and a signal circuit 60C that transmits an air pressure signal.
Unlike the signal circuit 60A of the second embodiment, the signal circuit 60C does not include the third solenoid valve 43 and does not include the branch circuit 63A, but instead includes a fifth circuit 65 branching from the fourth circuit 64. The difference is that a quick release valve 46 is connected in the middle.

Specifically, the signal circuit 60C includes a first solenoid valve 41 and a second solenoid valve 42 between the thirteenth port P13 and the open circuit 39. From the 13th port P13 to the first solenoid valve 41 is the first circuit 61, from the first solenoid valve 41 to the second solenoid valve 42 is the fourth circuit 64, and the second solenoid valve 42 is connected to the open circuit 39. has been done. The signal air pressure sensor 47 is connected to the fourth circuit 64. A fifth circuit 65 is branched from the fourth circuit 64 . In the fifth circuit 65, a quick release valve 46 is connected between the relay valve 40 and the 101st port.

The quick release valve 46 is connected to the upstream side of the fifth circuit 65, the open circuit 39, and the downstream side of the fifth circuit 65. The quick release valve 46 connects the open circuit 39 to the downstream side (relay valve 40) of the fifth circuit 65 when the air pressure on the upstream side (fourth circuit 64) of the fifth circuit 65 is less than a predetermined pressure. On the other hand, the quick release valve 46 connects the upstream side of the fifth circuit 65 to the downstream side of the fifth circuit 65 when the air pressure on the upstream side of the fifth circuit 65 (fourth circuit 64) is equal to or higher than a predetermined pressure. .

The air supply circuit 10 of this embodiment does not have a mechanism for releasing only the parking brake of the trailer for inspection, which the second embodiment had. Therefore, the operation of the air supply circuit 10 is substantially the same as the operation when the third solenoid valve 43 is off and no inspection is performed in the second embodiment, except for the relationship between the quick release valve 46 and the fifth circuit 65. be.

A case will be described in which the power to the ECU 21 is lost while the parking brake is in the operating state.
First, when the parking brake is in operation, the ECU 21 turns off the first solenoid valve 41A and turns on the second solenoid valve 42 or turns it off after opening to the atmosphere. Thereby, the fourth circuit 64 is connected to the open circuit 39, and the air pressure signal is maintained at atmospheric pressure. The atmospheric air pressure signal disables the relay valve 40 and no compressed air is supplied to the brake chamber from the second flow path 52, third flow path 53, and fourth flow path 54, so that the brake chamber applies the parking brake. Activate.

After this, when the power to the ECU 21 is lost, the first solenoid valve 41A is constantly supplied with compressed air from the air tank 13 even if it is off, so compressed air leaks into the fourth circuit 64 due to valve deterioration etc. There is a risk. At this time, the quick release valve 46 releases air under a predetermined pressure applied from the fourth circuit 64, which is lower than the operating pressure, to the open circuit 39. Therefore, even if compressed air leaks from the first solenoid valve 41A, the pressure in the fourth circuit 64 can be maintained at a pressure lower than the operating pressure of the quick release valve 46. Therefore, there is no fear that the relay valve 40 will operate and the parking brake in operation will be released.

Next, a case will be described in which the power to the ECU 21 is lost while the parking brake is in the released state.
First, when the parking brake is in a released state, the ECU 21 turns on the first solenoid valve 41A and turns off the second solenoid valve 42. As a result, the pneumatic pressure signal of the pneumatic pressure based on the compressed air from the air tank 13 is held in the fourth circuit 64, and the pneumatic pressure signal of the fourth circuit 64 is transmitted to the relay valve 40 via the quick release valve 46 and the fifth circuit 65. Activate. The relay valve 40 supplies compressed air from the air tank 13 to each brake chamber through the second flow path 52, the third flow path 53, and the fourth flow path 54 to release the parking brake.

After this, when the power to the ECU 21 is lost, both the first solenoid valve 41A and the second solenoid valve 42 are turned off and closed, and the fourth circuit sandwiched between the first solenoid valve 41A and the second solenoid valve 42 At 64, the air pressure immediately before the power loss is maintained. At this time, communication between the upstream and downstream portions of the fifth circuit 65 through the quick release valve 46 is also maintained by the pneumatic signal from the fourth circuit 64 . Therefore, the relay valve 40, which receives the pneumatic signal from the fourth circuit 64 via the fifth circuit 65, remains open to maintain the released state of the parking brake of the tractor.

According to this embodiment, in addition to effects (1) to (4) described in the first embodiment and effects (6) and (7) described in the second embodiment, the following effects can be obtained. It becomes like this.
(9) In a tractor (motorcycle) that does not tow a trailer, the structure of the air supply circuit 10 can be made simpler than in a tractor that tows a trailer.

(Fifth embodiment)
A fourth embodiment embodying the air supply circuit will be described with reference to FIG. 5. This embodiment differs from the first embodiment in a third electromagnetic valve 43 and a check valve 45.

As shown in FIG. 5, the third solenoid valve 43A provided in the signal circuit 60 is a solenoid valve for releasing only the parking brake of the trailer for inspection. The third solenoid valve 43A is normally kept on and turned off during inspection. The third solenoid valve 43A is a normally closed two-port, two-position solenoid valve, and its on/off state is controlled via the wiring E64. The third solenoid valve 43A is placed in the sealed position shown in FIG. 5 when turned off, and placed in the communication position when turned on. The third electromagnetic valve 43A blocks communication between the third circuit 63 and the fourth circuit 64 in the sealed position, and allows the third circuit 63 and the fourth circuit 64 to communicate in the communicating position.

The check valve 45A provided in the signal circuit 60 is a check valve with a spring, and prevents air leaking from the normally closed first solenoid valve 41 from flowing, thereby preventing an increase in the air pressure of the air pressure signal of the relay valve 40. To prevent.

The operation of such air supply circuit 10 will be explained.
First, when changing the parking brake from an activated state (on state) to a released state (off state), the ECU 21 turns on the first solenoid valve 41 and the third solenoid valve 43A, and turns off the second solenoid valve 42. As a result, the second circuit 62 , the third circuit 63 , and the fourth circuit 64 hold the air pressure signal of the air pressure based on the compressed air from the air tank 13 , and the air pressure signal of the air pressure based on the compressed air from the air tank 13 is held in the second circuit 62 , the third circuit 63 , and the fourth circuit 64 . The pneumatic signal activates relay valve 40. The relay valve 40 supplies compressed air from the air tank 13 to each brake chamber via the second flow path 52, the third flow path 53, and the fourth flow path 54. The ECU 21 detects the air pressure in the third circuit 63 using the signal air pressure sensor 47, and detects the air pressure in the third flow path 53 and the fourth flow path 54 using the supply air pressure sensor 48. When the detected pressures of the signal air pressure sensor 47 and the supply air pressure sensor 48 reach their respective target pressures, the ECU 21 turns off the first electromagnetic valve 41, turns off the second electromagnetic valve 42, and closes the second to fifth circuits 62. The parking brake is maintained in the released state by maintaining an air pressure signal of ~65. In addition, by turning on the second solenoid valve 42 and the third solenoid valve 43A with the first solenoid valve 41 turned off to make the air pressure signals of the second to fifth circuits 62 to 65 atmospheric pressure, the second solenoid valve 41 is turned off. The parking brake is activated by setting the air pressure in the flow path 52, the third flow path 53, and the fourth flow path 54 to atmospheric pressure. On the other hand, when the detected pressure of either the signal air pressure sensor 47 or the supply air pressure sensor 48 becomes lower than the corresponding target pressure, the ECU 21 turns off the second solenoid valve 42 and then turns off the first solenoid valve 41 and the third solenoid valve. 43A is turned on, compressed air from the air tank 13 is again supplied to the second circuit 62, third circuit 63, and fourth circuit 64 as an air pressure signal. As a result, the air pressure in the second flow path 52, third flow path 53, and fourth flow path 54 is adjusted and maintained at the target pressure, and compressed air at a predetermined pressure is supplied to the brake chamber, and the parking brake of the tractor is activated. It will be canceled. Further, compressed air at the target pressure is supplied to the trailer control valve, and the parking brake of the trailer is released.

Note that the ECU 21 may control ON/OFF of the first electromagnetic valve 41 and the second electromagnetic valve 42 based on the pressure detected by either the signal air pressure sensor 47 or the supply air pressure sensor 48. Further, the ECU 21 may learn from the signal air pressure sensor 47 the air pressure required by the signal circuit 60 in order to make the air pressure detected by the supply air pressure sensor 48 a target air pressure.

Next, when changing the parking brake from the released state to the activated state, the ECU 21 turns off the first solenoid valve 41 and turns on the second solenoid valve 42 and the third solenoid valve 43A. Thereby, the third circuit 63 and the fourth circuit 64 are connected to the open circuit 39, and the air pressure signal is maintained at atmospheric pressure. The atmospheric air pressure signal causes the relay valve 40 to be inactivated, and the brake chambers to which compressed air is not supplied from the second flow path 52, the third flow path 53, and the fourth flow path 54 activate the parking brake. The ECU 21 detects the air pressure in the third circuit 63 using the signal air pressure sensor 47, and detects the air pressure in the third flow path 53 and the fourth flow path 54 using the supply air pressure sensor 48. The ECU 21 confirms that the pressures detected by the signal air pressure sensor 47 and the supply air pressure sensor 48 are the respective atmospheric pressures. The ECU 21 may turn off the second solenoid valve 42 and the third solenoid valve 43A when the detected pressure becomes atmospheric pressure. At this time, when the pressure detected by either the signal air pressure sensor 47 or the supply air pressure sensor 48 is no longer atmospheric pressure, the ECU 21 turns on the second solenoid valve 42 and the third solenoid valve 43A to bring the pressure to atmospheric pressure. Make it. Thereby, the air pressure in the third flow path 53 and the fourth flow path 54 is maintained at atmospheric pressure. Therefore, the brake chamber is maintained at atmospheric pressure and the parking brake of the tractor is operated. Further, the air pressure of the trailer control valve is set to atmospheric pressure, and the parking brake of the trailer is operated.

The air supply circuit 10 can also release only the parking brake of the trailer for inspection. When performing an inspection, the ECU 21 first turns on the second solenoid valve 42 and the third solenoid valve 43A to activate (on) the parking brake of the tractor and trailer. Next, the third solenoid valve 43A is turned off to maintain the air pressure in the fourth circuit 64, thereby maintaining the operating state of the parking brake of the tractor. Subsequently, when the first solenoid valve 41 is turned on, compressed air is supplied to the port P31 via the third circuit 63 and the sixth circuit 66, and the parking brake of the trailer is released. As a result, the parking brake of the trailer is released, and only the parking brake of the tractor can be inspected. Even if power is lost during an inspection, only the parking brake of the tractor can be kept in operation. This test is to see if the tractor to which the trailer is connected can be kept stopped on a slope with a 12% gradient using only the tractor's parking brake, with the trailer's parking brake released.

The operation of this embodiment will be explained.
By the way, the ECU 21 may lose power due to a disconnection or the like. At this time, it is necessary to maintain the released state or the activated state at the time of power loss so that the operating state of the parking brake does not differ from the operation performed by the driver immediately before the power loss. That is, it is necessary to prevent the parking brake from switching from a released state to an activated state or from an activated state to a released state due to power loss of the ECU 21. In this regard, according to the present embodiment, even if the ECU 21 loses power due to a disconnection or the like, the operating state of the parking brake is maintained in the operating state at the time of power loss. In the following description, it is assumed that the inspection is not for the parking brake of the trailer, that the normally closed third solenoid valve 43A is open, and that the third circuit 63 and the fourth circuit 64 are in communication.

First, a case will be described in which the power to the ECU 21 is lost while the parking brake is in the operating state.
Immediately before power loss, the first solenoid valve 41 is turned off, the second solenoid valve 42 is turned on or turned off after opening to the atmosphere, and the second circuit 62, third circuit 63, and fourth circuit 64 are all opened to the atmosphere. has been done. Due to the power loss, the first solenoid valve 41, the second solenoid valve 42, and the third solenoid valve 43A, which are normally closed, are all turned off and closed, and are sandwiched between the check valve 45A and the second solenoid valve 42. The atmospheric pressure immediately before the power loss is maintained in the third circuit 63 and fourth circuit 64. Therefore, the relay valve 40, which receives the pneumatic signal from the fourth circuit 64, remains closed to maintain the operating state of the parking brake of the tractor. Further, the trailer control valve receiving the pneumatic signal from the third circuit 63 maintains the operating state of the parking brake of the trailer.

By the way, even if the first electromagnetic valve 41 is off, compressed air is constantly supplied from the air tank 13, so there is a risk that compressed air may leak to the check valve 45A side due to deterioration of the valve or the like. At this time, the first solenoid valve 41 connects the second circuit 62 on the check valve 45A side to the open circuit 39, so the leaked compressed air is released to the atmosphere and the pressure on the check valve 45A side is increased. Maintain atmospheric pressure. Furthermore, the check valve 45A maintains its closed state because it will not open unless a predetermined valve opening pressure is applied. In other words, the compressed air leaking from the first solenoid valve 41 increases the air pressure in the third circuit 63 and the fourth circuit 64 via the check valve 45A, opens the relay valve 40, and releases the operating parking brake. There is no fear. Therefore, the air pressure signals of the third circuit 63 and the fourth circuit 64 are maintained at the same atmospheric pressure as immediately before the power loss even after the power loss, and therefore are stable and highly reliable.

Next, a case will be described in which the power to the ECU 21 is lost while the parking brake is in the released state.
Since the parking brake is in the released state, immediately before the power loss, the first solenoid valve 41 is turned on or turned off after pressure adjustment, the second solenoid valve 42 is turned off, and the third solenoid valve 43A is turned on, and the third circuit 63 And the fourth circuit 64 is maintained at a predetermined air pressure. When the first solenoid valve 41 and the second solenoid valve 42, which are normally closed, are both turned off and closed due to power loss, the third circuit 63 sandwiched between the check valve 45A and the second solenoid valve 42 The predetermined air pressure immediately before the power loss is maintained in the fourth circuit 64. Therefore, the relay valve 40, which receives a pneumatic pressure signal of a predetermined pneumatic pressure from the fourth circuit 64, maintains the open state to maintain the released state of the parking brake of the tractor. Further, the trailer control valve receiving the pneumatic signal from the third circuit 63 maintains the released state of the parking brake of the trailer.

By the way, when the first solenoid valve 41 is turned off, it connects the second circuit 62 on the check valve 45A side to the open circuit 39, but since the check valve 45A does not allow air to flow from the third circuit 63 to the second circuit 62, The air pressure in the third circuit 63 and the fourth circuit 64 will not decrease, and there is no fear that the parking brake will operate while it is being released. Therefore, the air pressure signals of the third circuit 63 and the fourth circuit 64 are maintained at the same air pressure as immediately before the power loss even after the power loss, and therefore are stable and highly reliable.

Note that when the parking brake is in the released state, the released state is maintained, but the parking brake can also be operated after moving the vehicle to an appropriate position. That is, the release valve 101 is connected to the fifth circuit 65 branching from the fourth circuit 64 together with the relay valve 40 . If the parking brake is in the released state when the power is lost to the ECU 21, the parking brake will be kept in the released state even after the power is lost, but when the release valve 101 is opened, the fifth circuit 65, the fourth circuit 64, and the third circuit 63 is released to atmospheric pressure. Thereby, the parking brake of the tractor can be switched from the released state to the activated state, and the parking brake of the trailer can be switched from the released state to the activated state, and these activated states are maintained.

According to this embodiment, in addition to the effects (1) to (4) described in the first embodiment, the following effects can be obtained.
(5) By operating the third solenoid valve 43A, the operating state of the parking brake of the tractor and the operating state of the parking brake of the trailer can be made into different states. For example, by blocking the pneumatic signal to the relay valve 40 with the third solenoid valve 43A, it is possible to release only the trailer's parking brake while keeping the tractor's parking brake operating, and it is possible to inspect only the tractor's parking brake. Be able to do it. Specifically, after operating the parking brakes of the tractor and trailer, the third solenoid valve 43A is turned off, allowing compressed air to be supplied to the trailer control valve, and disabling compressed air to be supplied to the relay valve 40. can do. Thereby, the parking brake of the trailer can be released while the parking brake of the tractor remains activated.

(10) Since the third solenoid valve 43A is normally closed, even if air leaks from the first solenoid valve 41 when the power of the ECU 21 that controls on/off of the solenoid valve is lost, the normally closed third solenoid valve 43A It is possible to prevent a pneumatic signal from being applied to the relay valve 40 by the valve 43A.

(Other embodiments)
Each of the above embodiments can be modified and implemented as follows. The above embodiments and the following modified examples can be implemented in combination with each other within a technically consistent range.

- In each of the above embodiments, the supply air pressure sensor 48 is provided downstream of the relay valve 40 in the supply flow path 50, and the signal air pressure sensor 47 is provided in the third circuit 63 or the fourth circuit 64 of the signal circuit 60. However, the present invention is not limited to this, and the supply air pressure sensor and the signal air pressure sensor may be provided on either one, as long as the operating state of the parking brake can be controlled. Further, if detailed pressure control is not required, control may be performed based on time or the like, and it is not necessary to provide both a supply air pressure sensor and a signal air pressure sensor. This allows the structure of the air supply circuit to be simplified.

- In the sixth circuit 66, in the case of a configuration in which there is no quick release valve between the third circuit 63 and the 31st port P31, a quick release valve is provided between the third circuit 63 and the 31st port P31. Good too.

- In the case of a configuration in which the fifth circuit 65 does not have a quick release valve between the fourth circuit 64 and the relay valve 40, a quick release valve may be provided between the fourth circuit 64 and the relay valve 40. .

- As shown in FIG. 6, in the second embodiment, the third solenoid valve 43 of the signal circuit 60 may be replaced with a normally closed third solenoid valve 43A. The third solenoid valve 43A is normally turned on so that the air pressures in the third circuit 63 and the fourth circuit 64 are adjusted by the first solenoid valve 41 and the second solenoid valve 42. On the other hand, when the power to the ECU 21 is lost and the second solenoid valve 42 and the third solenoid valve 43A are turned off, the air pressure immediately before the power loss is maintained in the third circuit 63 and the fourth circuit 64, and the parking brake of the tractor and the trailer The operating state of the parking brake is maintained. Further, even if compressed air from the air tank 13 leaks through the first solenoid valve 41, the third circuit 63 and the fourth circuit 64 are cut off by the third solenoid valve 43A, and the third circuit 63 is opened. It is connected to circuit 39. Therefore, there is no risk that the leaked compressed air will increase the air pressure in the third circuit 63 and the fourth circuit 64, causing the parking brake in operation to be released.

- As shown in FIG. 7, in the first embodiment, the check valve 45 of the signal circuit 60 may be replaced with a normally closed fourth solenoid valve 44. The fourth solenoid valve 44 is normally turned on so that the air pressures in the third circuit 63 and the fourth circuit 64 are adjusted by the first solenoid valve 41 and the second solenoid valve 42 . On the other hand, when the power to the ECU 21 is lost and the fourth solenoid valve 44 and the second solenoid valve 42 are turned off, the air pressure immediately before the power loss is maintained in the third circuit 63 and the fourth circuit 64, and the parking brake of the tractor is The trailer parking brake remains operational. Further, even if compressed air from the air tank 13 leaks through the first solenoid valve 41, the second circuit 62 and the third circuit 63 are cut off by the fourth solenoid valve 44, and the second circuit 62 is opened. It is connected to circuit 39. Therefore, there is no risk that the leaked compressed air will increase the air pressure in the third circuit 63 and the fourth circuit 64, causing the parking brake in operation to be released. In the fifth embodiment as well, the check valve 45 of the signal circuit 60 may be replaced with a normally closed fourth solenoid valve.

- In the first and second embodiments described above, the case where a pneumatic signal is transmitted from the signal circuit 60 to the parking brake of a trailer is illustrated. However, the present invention is not limited to this, and the air pressure signal to be transmitted to the parking brake of the trailer may be obtained from the second flow path 52 of the supply flow path 50.

As shown in FIG. 8, a 31st port P31 connected to the trailer control valve may be provided in a branch flow path 52A branched from the second flow path 52. Further, at this time, the third solenoid valve 43 may be removed from the signal circuit 60 and provided as a third solenoid valve 43B downstream of the branch flow path 52A of the second flow path 52. Since the third solenoid valve 43B is normally open, both the parking brake of the tractor and the parking brake of the trailer are normally operated according to the output of the relay valve 40. Therefore, the operation of the tractor parking brake and the trailer parking brake are synchronized. On the other hand, by closing the third solenoid valve 43 for inspection, the operation of the parking brake of the tractor and the operation of the parking brake of the trailer can be made asynchronous. For example, it becomes possible to release the parking brake of a trailer while keeping the parking brake of the tractor operating.

As shown in FIG. 9, the normally open third solenoid valve 43B shown in FIG. 8 may be replaced with a normally closed third solenoid valve 43C. Since the third solenoid valve 43C is normally closed, normally, by turning on the third solenoid valve 43C, both the parking brake of the tractor and the parking brake of the trailer operate according to the output of the relay valve 40. Therefore, the operation of the tractor parking brake and the trailer parking brake are synchronized. On the other hand, by turning off the third solenoid valve 43C for inspection, the operation of the parking brake of the tractor and the operation of the parking brake of the trailer can be made asynchronous. Further, when the power to the ECU 21 is lost and the third solenoid valve 43C is turned off, the air pressure immediately before the power loss is maintained in the third flow path 53 and the fourth flow path 54, and the operating state of the parking brake of the tractor is maintained. Ru.

- In each embodiment, the check valve 45 without a spring may be replaced with a check valve 45A with a spring. Further, the check valve 45A with a spring may be replaced with a check valve 45 without a spring.

- As shown in FIG. 10, in the third embodiment, the check valve 45 of the signal circuit 60B may be replaced with a normally closed fourth solenoid valve 44. The fourth solenoid valve 44 is normally on, and the air pressure in the fourth circuit 64 is adjusted by the first solenoid valve 41 and the second solenoid valve 42 . On the other hand, when the power to the ECU 21 is lost and the fourth solenoid valve 44 is turned off, the air pressure immediately before the power loss is maintained in the fourth circuit 64 between the fourth solenoid valve 44 and the second solenoid valve 42, and the tractor The operating state of the parking brake is maintained. Furthermore, even if the compressed air from the air tank 13 leaks through the first solenoid valve 41, the fourth solenoid valve 44 cuts off the second circuit 62 and the fourth circuit 64, and the second circuit 62 opens. It is connected to circuit 39. Therefore, there is no risk that the leaked compressed air will increase the air pressure in the fourth circuit 64 and cause the parking brake in operation to be released.

- In each of the above embodiments, the air supply circuit 10 has been described as being used for a tractor only, or a coupled vehicle including a tractor and a trailer. In other embodiments, the air supply circuit may be used in other vehicles such as passenger cars and railway vehicles.

10... Air supply circuit, 13... Air tank, 21... ECU, 39... Open circuit, 40... Relay valve, 41, 41A... First solenoid valve, 42... Second solenoid valve, 43, 43B... Third solenoid valve, 44 ...Fourth solenoid valve, 45...Check valve, 46...Quick release valve, 47...Signal air pressure sensor, 48...Supply air pressure sensor, 49...Open circuit, 49...Exhaust port, 50...Supply flow path, 51...First flow Channel, 52...Second channel, 52A...Branch channel, 53...Third channel, 54...Fourth channel, 60, 60A, 60B, 60C...Signal circuit, 61...First circuit, 62...Second channel Circuit, 63...Third circuit, 63A...Branch circuit, 64...Fourth circuit, 65...Fifth circuit, 66...Sixth circuit, 101...Open valve.

Claims (8)

a supply flow path having a relay valve between the air tank and a brake chamber for a parking brake and supplying air;
a signal circuit that transmits a pneumatic pressure signal and includes a normally closed first solenoid valve and a normally closed second solenoid valve that are arranged in series between the air tank and an open circuit that is open to the atmosphere;
a control device that controls switching on and off of the first electromagnetic valve and switching on and off of the second electromagnetic valve,
An air supply circuit that applies an air pressure signal between the first solenoid valve and the second solenoid valve to the relay valve as a control pressure signal for controlling the relay valve. The air supply circuit according to claim 1, further comprising a release valve capable of releasing the control pressure signal applied to the relay valve to the atmosphere. An air pressure holding mechanism is provided between the first electromagnetic valve and the relay valve to prevent air pressure from the first electromagnetic valve from being transmitted to the relay valve when the first electromagnetic valve is off. The air supply circuit according to item 1 or 2. The signal circuit is provided with a check valve that allows air to flow from the first solenoid valve located on the air tank side to the second solenoid valve located on the open circuit side,
The control pressure signal is an air pressure signal between the check valve and the second solenoid valve,
The air supply circuit according to claim 3, wherein the first solenoid valve is a 3-port valve that opens a space between it and the check valve to the atmosphere when the first solenoid valve is off. the signal circuit has a quick release valve;
When the pneumatic pressure signal has a pneumatic pressure equal to or higher than the operating pressure of the quick release valve, the pneumatic pressure signal is applied as the control pressure signal to the relay valve via the quick release valve, and the pneumatic signal is applied to the relay valve as the control pressure signal through the quick release valve. 4. The air supply circuit of claim 3, wherein atmospheric pressure is applied as the control pressure signal to the relay valve via the quick release valve when the air pressure is less than the operating pressure of . the air supply circuit is connected to a brake chamber of the tractor and a trailer control valve;
The signal circuit includes a third solenoid valve, and the pneumatic signal is outputted to the trailer control valve and applied to the relay valve via the third solenoid valve,
The air supply circuit according to any one of claims 1 to 5, wherein compressed air regulated by the relay valve is supplied to a brake chamber of the tractor. The third solenoid valve is normally closed,
The air supply circuit according to claim 6, wherein the control device controls switching on and off of the third solenoid valve. The air supply circuit according to claim 6 or 7, wherein the air pressure signal is output to the trailer control valve via a quick release valve.

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