CN113613975B

CN113613975B - Air supply circuit

Info

Publication number: CN113613975B
Application number: CN201980093013.9A
Authority: CN
Inventors: 板谷将治; 松家伸成
Original assignee: Nabtesco Automotive Corp
Current assignee: Nabtesco Automotive Corp
Priority date: 2018-12-28
Filing date: 2019-12-27
Publication date: 2024-07-19
Anticipated expiration: 2039-12-27
Also published as: JPWO2020138394A1; CN113613975A; WO2020138394A1; JP7438979B2

Abstract

Provided is an air supply circuit capable of maintaining the operation state of a parking brake even if an electronic control device for controlling the parking brake loses power. The air supply circuit (10) is provided with: a supply flow path (50) having a relay valve (40) between the air tank (13) and a brake chamber for the parking brake, the supply flow path (50) being used for supplying air; a signal circuit (60) in which a normally closed first solenoid valve (41) and a normally closed second solenoid valve (42) are arranged in series between the gas tank (13) and a release circuit (39) that is open to the atmosphere, the signal circuit (60) being configured to transmit an air pressure signal; and an ECU (21) that controls switching of opening and closing of the first electromagnetic valve (41) and switching of opening and closing of the second electromagnetic valve (42), respectively. An air pressure signal between the first solenoid valve (41) and the second solenoid valve (42) is applied to the relay valve (40) as a control pressure signal for controlling the relay valve (40).

Description

Air supply circuit

Technical Field

The present invention relates to an air supply circuit for supplying air to a brake mechanism of a vehicle.

Background

An air pressure brake system including a Service brake (Service brake) mechanism and a parking brake mechanism is provided in a vehicle. The air pressure brake system includes an air supply circuit that supplies compressed air from a compressor and supplies the dried compressed air to the parking brake mechanism. Recently, an air supply circuit provided with and controlled by an electronic control device has been proposed (for example, refer to patent document 1).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2007-326516

Disclosure of Invention

Problems to be solved by the invention

However, in the above system, it is not considered to maintain the parking brake in an appropriate operating state when the electronic control device loses power.

The invention aims to provide an air supply circuit capable of maintaining the action state of a parking brake even if an electronic control device for controlling the parking brake loses power.

Solution for solving the problem

The air supply circuit for achieving the above object comprises: a supply flow path having a relay valve between the gas tank and a brake chamber for parking brake, the supply flow path being configured to supply air; a signal circuit having a normally closed first solenoid valve and a normally closed second solenoid valve arranged in series between the gas tank and a release circuit open to the atmosphere, the signal circuit for transmitting an air pressure signal; and a control device that controls switching of opening and closing of the first electromagnetic valve and switching of opening and closing of the second electromagnetic valve, respectively, wherein an air pressure signal between the first electromagnetic valve and the second electromagnetic valve is applied to the relay valve as a control pressure signal for controlling the relay valve.

In this case, since the first solenoid valve and the second solenoid valve are normally closed solenoid valves, when the control device that controls the opening/closing of these solenoid valves loses power, the air pressure between the first solenoid valve and the second solenoid valve immediately before the loss of power is held 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, which inputs the air pressure signal as the control pressure signal, is maintained. Thus, even if the control device for controlling the parking brake loses power, the operating state of the parking brake can be maintained.

In one embodiment, there may be a release valve capable of releasing the control pressure signal applied to the relay valve to the atmosphere.

In this case, the parking brake held in the released state by the air pressure signal based on the pressure of the compressed air can be brought into the activated state by the operation of the release valve.

In one embodiment, an air pressure maintaining mechanism may be provided between the first solenoid valve and the relay valve, the air pressure maintaining mechanism being such that air pressure from the first solenoid valve is not transmitted to the relay valve when the first solenoid valve is closed.

The parking brake is released by the air pressure rising and is operated by the air pressure falling to the atmospheric pressure. In this regard, in this case, there is no concern that the parking brake will be released due to an increase in air pressure when the first electromagnetic valve is closed.

In one embodiment, the signal circuit may be provided with a check valve that allows air to flow from the first solenoid valve disposed on the tank side to the second solenoid valve disposed on the release circuit side, the control pressure signal may be an air pressure signal between the check valve and the second solenoid valve, and the first solenoid valve may be a three-way valve that opens the space between the first solenoid valve and the check valve to the atmosphere when the first solenoid valve is closed.

In this case, although the first solenoid valve is a three-way valve, the check valve can maintain the air pressure on the second solenoid valve side higher than the air pressure on the first solenoid valve side, so even if the first solenoid valve and the second solenoid valve are both closed due to the control device losing power, the pressure of the air pressure signal is maintained the same before and after losing power.

In addition, when the first solenoid valve is closed, even if compressed air leaks from the first solenoid valve, the leaked compressed air is guided to a port of the first solenoid valve that is open to the atmosphere due to the sealing force of the check valve. This prevents the air pressure on the second solenoid valve side from rising, and thus the parking brake once in the on state is not suddenly released. That is, the air pressure maintaining mechanism is constituted by the check valve and the second solenoid valve.

In one embodiment, the signal circuit may have a quick release valve, the air pressure signal being applied as the control pressure signal to the relay valve via the quick release valve when the air pressure signal has an air pressure that is above an operating pressure of the quick release valve, and atmospheric pressure being applied as the control pressure signal to the relay valve via the quick release valve when the air pressure signal has an air pressure that is less than the operating pressure of the quick release valve.

In this case, when the first solenoid valve and the second solenoid valve are closed by the control device losing power, the control pressure signal to the relay valve is maintained in the state before losing.

When the first solenoid valve is closed, even if compressed air leaks from the first solenoid valve, the control pressure signal is maintained at the atmospheric pressure as long as the air pressure signal between the first solenoid valve and the second solenoid valve does not rise to the operating pressure of the quick release valve. Further, even if the quick release valve is slowly applied with an air pressure equal to or lower than the operating pressure, the control pressure signal does not rise to the operating pressure due to leakage to the release circuit. That is, the air pressure maintaining mechanism is constituted by a quick release valve.

In one embodiment, the air supply circuit may be connected to a brake chamber of a tractor and a trailer control valve, the signal circuit having a third solenoid valve, the signal circuit outputting the air pressure signal to the trailer control valve and applying the air pressure signal to the relay valve via the third solenoid valve, the air supply circuit supplying compressed air regulated by the relay valve 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 cutting off the air pressure signal to the relay valve by the third solenoid valve, only the parking brake of the trailer can be released while the parking brake of the tractor is operated, and only the parking brake of the tractor can be inspected. In addition, here, the parking brake of the trailer includes a parking brake using a service brake of the trailer.

In one embodiment, the third electromagnetic valve may be a normally closed electromagnetic valve, and the control device may control switching of opening and closing of the third electromagnetic valve.

In this case, since the third electromagnetic valve is a normally closed electromagnetic valve, when the control device that controls the opening/closing of the electromagnetic valve loses power, even if air leaks from the first electromagnetic valve, the air pressure signal can be prevented from being applied to the relay valve by the normally closed third electromagnetic valve.

In one embodiment, the air pressure signal may be output to the trailer control valve via a quick release valve.

In this case, the air pressure signal is supplied to the trailer control valve via the quick release valve. When compressed air is not supplied to the trailer control valve, even if a pressure smaller than the operating pressure is given to the air pressure signal due to leakage of compressed air from the first solenoid valve, the quick release valve is opened to the atmosphere, and thus the parking brakes in the tractor and trailer do not become released.

Drawings

Fig. 1 is a circuit diagram showing a schematic configuration of a first embodiment in which an air supply circuit is embodied.

Fig. 2 is a circuit diagram showing a schematic configuration of a second embodiment in which an air supply circuit is embodied.

Fig. 3 is a circuit diagram showing a schematic configuration of a third embodiment in which an air supply circuit is embodied.

Fig. 4 is a circuit diagram showing a schematic configuration of a fourth embodiment in which an air supply circuit is embodied.

Fig. 5 is a circuit diagram showing a schematic configuration of a fifth embodiment in which an air supply circuit is embodied.

Fig. 6 is a circuit diagram showing a schematic configuration of another embodiment in which the air supply circuit is embodied.

Fig. 7 is a circuit diagram showing a schematic configuration of another embodiment in which the air supply circuit is embodied.

Fig. 8 is a circuit diagram showing a schematic configuration of another embodiment in which the air supply circuit is embodied.

Fig. 9 is a circuit diagram showing a schematic configuration of another embodiment in which the air supply circuit is embodied.

Fig. 10 is a circuit diagram showing a schematic configuration of another embodiment in which the air supply circuit is embodied.

Detailed Description

(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 a driving source. A tractor is a vehicle that is capable of coupling to a trailer. That is, the trailer can be coupled to the tractor.

In general, a service brake mechanism and a parking brake mechanism are provided in a tractor. By supplying air to the service brake mechanism, the service brake is actuated, and when air is discharged from the service brake mechanism, the service brake is released (deactivated). 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 actuated. 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 a gas tank 13 and an air supply circuit 10, and the gas tank 13 stores 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 via the 13 th port P13, and supplies the adjusted compressed air to the 21 st port P21 and the 22 nd port P22, thereby releasing or operating the parking brake of the tractor via the 21 st port P21 and the 22 nd port P22.

A trailer control valve (TCV: trailer Control Valve) is connected to the 31 st port P31 of the air supply circuit 10. The trailer control valve releases or operates the trailer's parking brake by controlling the supply and exhaust of air to the trailer's air pressure circuit. Here, the parking brake of the trailer is a service brake of the trailer, but for convenience of explanation, the parking brake of the trailer will be described below.

The structure of the air supply circuit 10 is described.

In the air supply circuit 10, a plurality of wirings E61 to E66 are connected to the ECU 21 as a control device. In addition, the description of other wirings is omitted. The ECU 21 includes a calculation unit, a volatile memory unit, and a nonvolatile memory unit, and the ECU 21 supplies a command value to the air supply circuit in accordance with a program stored in the nonvolatile memory unit. The ECU 21 is connected to other control devices such as a vehicle ECU via a wiring E61 as a communication line of an in-vehicle LAN or the like so as to be able to transmit vehicle information with these control devices.

The air supply circuit 10 includes: a supply flow path 50 for supplying compressed air from the gas tank 13 to the ports P21 and P22; and a signal circuit 60 for transmitting an air pressure signal for adjusting the air pressure supplied to the parking brake.

The supply flow path 50 is a flow path from the 13 th port P13 to the 21 st port P21 and the 22 nd port P22, and includes the relay valve 40 and a branching portion branching to the 21 st port P21 and the 22 nd port P22 in the middle of the flow path. The first flow path 51 is from the 13 th 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 branching portion, the third flow path 53 is from the branching portion to the 21 st port P21, and the fourth flow path 54 is from the branching portion to the 22 nd port P22.

The signal circuit 60 is used to transmit an air pressure signal for adjusting the strength of the parking brake to the relay valve 40 and to the trailer control valve via the 31 st port P31. The relay valve 40 releases or operates the parking brake of the tractor based on the air pressure signal. The trailer control valve releases or operates the parking brake of the tractor based on the air pressure signal.

The signal circuit 60 is a circuit from the 13 th port P13 to the release circuit 39, and includes the first solenoid valve 41, the check valve 45, the third solenoid valve 43, and the second solenoid valve 42 in this order from the upstream side of the circuit. The first circuit 61 is the 13 th port P13 to the input of the first solenoid valve 41, the second circuit 62 is the output of the first solenoid valve 41 to the input of the check valve 45, the third circuit 63 is the check valve 45 to the third solenoid valve 43, the fourth circuit 64 is the third solenoid valve 43 to the second solenoid valve 42, and the outlet of the second solenoid valve 42 is connected to the release circuit 39. The third circuit 63 is branched and is further connected to a sixth circuit 66 connected to the 31 st port P31 and a signal air pressure sensor (PU) 47 for detecting air pressure. The fourth circuit 64 branches off and is also connected to a fifth circuit 65 to which the relay valve 40 is connected. The fifth circuit 65 is connected to the release valve 101 via a 101 th port P101. The release circuit 39 communicates with a vent 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 ECU 21 loses power, or may be a valve that can be operated by another control device such as a vehicle ECU.

The check valve 45 allows the compressed air to flow in a direction (allowable direction) from the second circuit 62 to the third circuit 63. On the other hand, the check valve 45 prohibits the supply of the compressed air in the direction (prohibition direction) from the third circuit to the second circuit 62. The check valve 45 has a sealing force that does not allow the passage of air having a pressure smaller than a predetermined pressure even when the air flows in the allowable direction.

The ECU 21 is connected to the first solenoid valve 41 via a wiring E62, is connected to the third solenoid valve 43 via a wiring E64, and is connected to the second solenoid valve 42 via an E65. The ECU 21 is connected to the signal air pressure sensor 47 via a wiring E63, and is connected to the supply air pressure sensor 48 via a wiring E66. The ECU 21 can acquire the air pressure of the signal circuit 60 from the signal air pressure sensor 47, and can acquire 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 two-position solenoid valves that are switched by switching on and off of a power supply under the control of the ECU 21. Hereinafter, a description will be given of a state in which the power is turned off and a state in which the power is turned on.

The first solenoid valve 41 is a normally closed three-way two-position solenoid valve, and is controlled to be opened/closed via a wiring E62. The first solenoid valve 41 is disposed at a sealing position shown in fig. 1 when closed, and is disposed at a communication position when open. The first solenoid valve 41, in the sealed position, cuts off the communication between the first circuit 61 and the second circuit 62, and communicates the second circuit 62 with the release circuit 39. The first solenoid valve 41 communicates the first circuit 61 with the second circuit 62 at the communication position, and cuts off communication between the second circuit 62 and the release circuit 39.

The second solenoid valve 42 is a normally closed two-way two-position solenoid valve, and is controlled to be opened/closed via a wiring E65. The second solenoid valve 42 is disposed at a sealing position shown in fig. 1 when closed, and is disposed at a communication position when open. The second solenoid valve 42 cuts off communication between the fourth circuit 64 and the release circuit 39 when in the sealing position, and communicates the fourth circuit 64 with the release circuit 39 when in the communication 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 maintained closed and opened at the time of inspection. The third solenoid valve 43 is a normally open two-way two-position solenoid valve, and is controlled to be opened/closed via a wiring E64. The third solenoid valve 43 is disposed at the communication position shown in fig. 1 when closed, and is disposed at the sealing position when open. The third solenoid valve 43 cuts off communication between the third circuit 63 and the fourth circuit 64 in the sealing position, and communicates the third circuit 63 with the fourth circuit 64 in the communication position.

The operation of the air supply circuit 10 will be described.

First, when the parking brake is changed from the on state (open state) to the off state (closed state), the ECU 21 opens the first solenoid valve 41 and closes the third solenoid valve 43 and the second solenoid valve 42. Thereby, an air pressure signal based on the air pressure of the compressed air from the air tank 13 is held in the second, third, and fourth circuits 62, 63, 64, and the air pressure signal of the fourth circuit 64 operates the relay valve 40 via the fifth circuit 65. The relay valve 40 supplies the 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 of the third circuit 63 by the signal air pressure sensor 47, and detects the air pressures of the third flow path 53 and the fourth flow path 54 by 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 the respective target pressures, the ECU 21 closes the first solenoid valve 41 and opens the second solenoid valve 42 to bring the pressures of the air pressure signals of the second to fifth circuits 62 to 65 to the atmospheric pressure. On the other hand, when the detected pressure of either one of the signal air pressure sensor 47 and the supply air pressure sensor 48 is smaller than the corresponding target pressure, the ECU 21 turns on the first solenoid valve 41 after turning off the second solenoid valve 42, thereby setting the pressure of the air pressure signal to the pressure of the compressed air from the air tank 13. Accordingly, the air pressures of the second flow path 52, the third flow path 53, and the fourth flow path 54 are adjusted and maintained at the target pressures, and compressed air of a predetermined pressure is supplied to the brake chambers to release the parking brakes of the tractor. In addition, compressed air of a target pressure is supplied to the trailer control valve to release the parking brake of the trailer.

The ECU 21 may control the opening/closing of the first solenoid valve 41 and the second solenoid valve 42 based on the detected pressure of either the signal air pressure sensor 47 or the supply air pressure sensor 48. The ECU 21 may learn, from the signal air pressure sensor 47, the air pressure required for the signal circuit 60 so that the detected air pressure of the supply air pressure sensor 48 becomes the target air pressure.

Next, when the parking brake is changed from the released state to the activated state, the ECU 21 closes the first solenoid valve 41 and the third solenoid valve 43, and opens the second solenoid valve 42. Thereby, the third circuit 63 and the fourth circuit 64 are connected to the release circuit 39, and the pressure of the air pressure signal is maintained at the atmospheric pressure. The air pressure signal of the atmospheric pressure deactivates the relay valve 40, so that compressed air is not supplied from the second flow path 52, the third flow path 53, and the fourth flow path 54 to the brake chambers, and the brake chambers thereby activate the parking brakes. The ECU 21 detects the air pressure of the third circuit 63 by the signal air pressure sensor 47, and detects the air pressures of the third flow path 53 and the fourth flow path 54 by the supply air pressure sensor 48. The ECU 21 confirms whether the detected pressures of the signal air pressure sensor 47 and the supply air pressure sensor 48 are the atmospheric pressures, respectively. The ECU 21 may close the second electromagnetic valve 42 when the detected pressure is the 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 the atmospheric pressure, the ECU 21 opens the second electromagnetic valve 42 to bring the detected pressure to the atmospheric pressure. Thereby, the air pressure of the third flow path 53 and the fourth flow path 54 is maintained at the atmospheric pressure. Thus, the brake chamber is maintained at atmospheric pressure, thereby operating the parking brake of the tractor. In addition, the air pressure of the trailer control valve is set to the atmospheric pressure, and the parking brake of the trailer is operated.

In addition, the air supply circuit 10 can release only the parking brake of the trailer for inspection. At the time of the inspection, the ECU 21 first opens the second electromagnetic valve 42 and closes the third electromagnetic valve 43 to put the parking brakes of the tractor and the trailer into an operating state (open). Then, the third solenoid valve 43 is opened to maintain the air pressure of the fourth circuit 64, whereby the operating state of the parking brake of the tractor is maintained. Next, when the first solenoid valve 41 is opened, 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. During the inspection, even if the power supply is lost, the state in which only the parking brake of the tractor is operated can be maintained. This releases the parking brake of the trailer, and only the parking brake of the tractor can be checked. The inspection here is an inspection of whether or not the tractor to which the trailer is connected can be kept in a stopped state on a slope having a gradient of 12% only by the parking brake of the tractor in a state where the parking brake of the trailer is released.

The operation of the present embodiment will be described.

In addition, in the ECU 21, power may be lost due to disconnection or the like. At this time, it is necessary to maintain the released state or the operating state of the parking brake at the time of the power loss to avoid that the operating state of the parking brake is different from the operation of the driver immediately before the power loss. That is, it is necessary to prevent the parking brake from being switched from the released state to the activated state or from being switched from the activated state to the released state by the ECU 21 losing the power supply. In this regard, according to the present embodiment, even if the ECU 21 loses power due to disconnection or the like, the operating state of the parking brake is maintained in the operating state when the power is lost. In the following, when the inspection of the parking brake of the trailer is not performed, the third solenoid valve 43, which is normally open, is opened to communicate the third circuit 63 with the fourth circuit 64.

First, a case will be described in which the ECU 21 loses power when the parking brake is in an on state.

Immediately before the power is lost, the first solenoid valve 41 is closed, the second solenoid valve 42 is opened or closed after being opened to the atmosphere, so that the second circuit 62, the third circuit 63, and the fourth circuit 64 are all opened to the atmosphere. When power is lost at this time, the normally closed first solenoid valve 41 and second solenoid valve 42 are both closed to become off, and the atmospheric pressure immediately before the loss of power is maintained in the third circuit 63 and fourth circuit 64 interposed between the check valve 45 and second solenoid valve 42. Thus, the relay valve 40, which receives the air pressure signal from the fourth circuit 64, remains off, so that the operating state of the parking brake of the tractor is maintained. In addition, the trailer control valve, which receives the air pressure signal from the third circuit 63, causes the parking brake of the trailer to be maintained in an operating state.

Further, since the compressed air is always supplied from the air tank 13 even when the first electromagnetic valve 41 is closed, there is a possibility that the compressed air leaks to the check valve 45 side due to deterioration of the valve or the like. At this time, the first solenoid valve 41 communicates the second circuit 62 on the check valve 45 side with the release circuit 39, and thus releases the leaked compressed air to the atmosphere, thereby maintaining the pressure on the check valve 45 side at the atmospheric pressure. Further, the check valve 45 is not opened when a predetermined valve opening pressure is not applied, and thus the valve-closed state is maintained. In other words, the air pressure of the third and fourth circuits 63 and 64 is raised by the compressed air leaking from the first solenoid valve 41 via the check valve 45, and the relay valve 40 is opened to release the parking brake in operation. Therefore, the pressure of the air pressure signals of the third circuit 63 and the fourth circuit 64 is maintained at the same atmospheric pressure immediately before the power is lost even after the power is lost, and thus the stability and reliability are high.

Next, a case will be described in which the ECU 21 loses power when 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 opened or closed after the pressure is adjusted, and the second solenoid valve 42 is closed, so that the third circuit 63 and the fourth circuit 64 are maintained at the prescribed air pressure. When the first solenoid valve 41 and the second solenoid valve 42, which are normally closed when power is lost at this time, are both closed and turned off, a predetermined air pressure immediately before the power is lost is maintained in the third circuit 63 and the fourth circuit 64 interposed between the check valve 45 and the second solenoid valve 42. Accordingly, the relay valve 40 that receives the air pressure signal of the prescribed air pressure from the fourth circuit 64 is maintained open, so that the released state of the parking brake of the tractor is maintained. In addition, the trailer control valve that receives the air pressure signal from the third circuit 63 maintains the released state of the parking brake of the trailer.

Further, the first solenoid valve 41 communicates the second circuit 62 on the check valve 45 side with the release circuit 39 when closed, 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 does not drop, and there is no concern that the parking brake in the released state will be operated. Therefore, the air pressure signals of the third circuit 63 and the fourth circuit 64 are maintained at the same air pressure immediately before the power is lost even after the power is lost, and thus are stable and highly reliable.

In addition, the released state may be maintained when the parking brake is released, but the parking brake may be actuated after the vehicle is moved to an appropriate position. That is, the relay valve 40 is connected to the fifth circuit 65 branched from the fourth circuit 64, and the release valve 101 is connected. If the parking brake is in the released state when the ECU 21 loses power, the parking brake is also kept in the released state after the loss of power, but when the release valve 101 is opened, the fifth circuit 65, the fourth circuit 64, and the third circuit 63 are released to the atmospheric pressure. This makes it possible to switch the parking brake of the tractor from the released state to the activated state, switch the parking brake of the trailer from the released state to the activated state, and maintain the activated state.

According to the present embodiment, the following effects can be obtained.

(1) The first solenoid valve 41 and the second solenoid valve 42 are normally closed solenoid valves, and therefore when the ECU 21 that controls the opening/closing of these solenoid valves loses power, the air pressure between the first solenoid valve 41 and the second solenoid valve 42 immediately before the loss of power is maintained as the pressure of the air pressure signal between the first solenoid valve 41 and the second solenoid 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. Thus, even if the ECU 21 controlling the parking brake loses power, the operating state of the parking brake can be maintained.

(2) The parking brake held in the released state based on the air pressure signal having the pressure of the compressed air can be brought into the activated state by the operation of the release valve 101.

(3) The parking brake is released when the air pressure increases, and is operated when the air pressure is at the atmospheric pressure. Since the first solenoid valve 41 is a three-way valve, and the check valve 45 is provided downstream of the first solenoid valve 41, there is no concern that the parking brake will be released due to an increase in air pressure when the first solenoid valve 41 is closed.

(4) Although the first solenoid valve 41 is a three-way valve, the sealing force of the check valve 45 can keep the air pressure on the second solenoid valve 42 side higher than the air pressure on the first solenoid valve 41 side. Therefore, even if the ECU21 loses power and both the first solenoid valve 41 and the second solenoid valve 42 are closed, the pressure of the air pressure signal is maintained to be the same before and after the power is lost. That is, the air pressure maintaining mechanism is constituted by the check valve 45 and the second electromagnetic valve 42.

When the first solenoid valve 41 is closed, even if compressed air leaks from the first solenoid valve 41, the leaked compressed air is guided to a port of the first solenoid valve 41 that is open to the atmosphere by the check valve 45. This prevents the air pressure on the second solenoid valve 42 side from rising, and the parking brake once in the on state is not suddenly released.

(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 cutting off the air pressure signal to the relay valve 40 by the third solenoid valve 43, only the parking brake of the trailer can be released while the parking brake of the tractor is operated, and only the parking brake of the tractor can be inspected. In detail, the third solenoid valve 43 can be opened after the parking brakes of the tractor and trailer are operated, so that compressed air can be supplied to the trailer control valve and compressed air cannot be supplied to the relay valve 40. Thus, the parking brake of the trailer can be released while the parking brake of the tractor is operated.

(Second embodiment)

A second embodiment embodying an air supply circuit is described with reference to fig. 2. The signal circuit 60A of the present embodiment is different from the signal circuit 60 of the first embodiment. For convenience of explanation, the same components as those of the first embodiment are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

As shown in fig. 2, in the present embodiment, the air supply circuit 10 includes a supply flow path 50 and a signal circuit 60A for transmitting an air pressure signal, as in the first embodiment.

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-way two-position solenoid valve, and is controlled to be turned on/off by switching on/off the power supply from the wiring E62. The first solenoid valve 41A is disposed at a sealing position shown in fig. 2 when closed, and is disposed at a communication position when open. The first solenoid valve 41A cuts off the connection between the first circuit 61 and the third circuit 63 when in the sealing position, and connects the first circuit 61 and the third circuit 63 when in the communicating position. The branch circuit 63A of the third circuit 63 is connected to the release 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 release circuit 39, and the sixth circuit 66. When the air pressure in the branch circuit 63A is smaller than the predetermined pressure, the quick release valve 46 connects the release circuit 39 to the sixth circuit 66. On the other hand, when the air pressure in the branch circuit 63A is equal to or higher than the predetermined pressure, the quick release valve 46 connects the third circuit 63 to the sixth circuit 66 via the branch circuit 63A.

The ECU 21 in the present embodiment will be described as losing power.

Immediately before the power is lost, the first solenoid valve 41A is closed, the second solenoid valve 42 is opened or closed after being opened to the atmosphere, and thus the third circuit 63 and the fourth circuit 64 are opened to the atmosphere. When power is lost at this time, both the first solenoid valve 41A and the second solenoid valve 42 are closed to become off, and the atmospheric pressure immediately before the loss of power is maintained in the third circuit 63 and the fourth circuit 64 interposed between the first solenoid valve 41A and the second solenoid valve 42. Thus, the relay valve 40, which receives the air pressure signal from the fourth circuit 64 via the fifth circuit 65, is maintained off, so that the operating state of the parking brake of the tractor is maintained. When the branch circuit 63A is smaller than the predetermined pressure, the quick release valve 46 connects the sixth circuit 66 to the release circuit 39. Thus, the trailer control valve receiving atmospheric pressure from the sixth circuit 66 maintains the parking brake of the trailer in an active state.

In addition, when the parking brake is in operation, the first solenoid valve 41A is always supplied with compressed air from the air tank 13 even if it is closed, and therefore, there is a possibility that the compressed air leaks into the third circuit 63 due to deterioration of the valve or the like. At this time, the quick release valve 46 releases air having a pressure lower than the predetermined pressure applied from the branch circuit 63A to the release circuit 39. Therefore, even if the 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. Further, since the operating pressure of the quick release valve 46 is lower than the operating pressure of the relay valve 40, there is no concern that the leaked compressed air will raise the air pressure in the third and fourth circuits 63 and 64, nor that the parking brake in operation will be released. Therefore, the air pressure signals of the third circuit 63 and the fourth circuit 64 are maintained at the same atmospheric pressure immediately before the power is lost even after the power is lost, so that stability and reliability are high.

Immediately before the power is lost, the first solenoid valve 41A is opened or closed after the pressure is adjusted, and the second solenoid valve 42 is closed, so that the third circuit 63 and the fourth circuit 64 are maintained at a prescribed air pressure. When power is lost at this time, both the first solenoid valve 41A and the second solenoid valve 42 are closed to become off, and the air pressure immediately before the loss of power is maintained in the third circuit 63 and the fourth circuit 64 interposed between the first solenoid valve 41A and the second solenoid valve 42. At this time, communication between the branch circuit 63A and the sixth circuit 66 by the quick release valve 46 based on the air pressure signal of the branch circuit 63A is also maintained. Accordingly, the relay valve 40 that receives the air pressure signal from the fourth circuit 64 via the fifth circuit 65 is maintained open, so that the released state of the parking brake of the tractor is maintained. The quick release valve 46 when the branch circuit 63A is at a predetermined pressure or higher connects the branch circuit 63A to the sixth circuit 66. Thus, the trailer control valve receiving the air pressure signal from the branch circuit 63A is such that the released state of the parking brake of the trailer is maintained.

Further, since the first solenoid valve 41A is always supplied with compressed air from the air tank 13 even when it is closed, there is a possibility that the compressed air leaks into the third circuit 63 due to deterioration of the valve or the like. However, even if the compressed air leaks into the third circuit 63, the air pressures of the third circuit 63 and the fourth circuit 64 to which the compressed air is originally supplied are maintained, so that the released state of the parking brake is maintained. In other words, the air pressure in the third circuit 63 and the fourth circuit 64 is reduced, and the released parking brake is not likely to be operated. Therefore, the air pressure signals of the third circuit 63 and the fourth circuit 64 are maintained at the same air pressure immediately before the power is lost even after the power is lost, so that the stability and reliability are high.

In addition, as in the first embodiment, the release valve 101 is opened, whereby the fifth circuit 65, the fourth circuit 64, and the third circuit 63 are released to the atmospheric pressure. Thus, the parking brake of the tractor is switched from the released state to the activated state, and the parking brake of the trailer is switched from the released state to the activated state, and the activated state can be maintained.

According to the present embodiment, the following effects can be obtained in addition to the effects (1) to (3) described in the first embodiment.

(6) Since the air pressure signal is applied to the relay valve 40 as the control pressure signal via the quick release valve 46, the control pressure signal to the relay valve 40 is maintained in a state before the loss when the first solenoid valve 41A and the second solenoid valve 42 are closed due to the ECU 21 losing power.

When the first solenoid valve 41A is closed, even if compressed air leaks from the first solenoid valve 41A, the control pressure signal is maintained at the atmospheric pressure as long as the air pressure signal between the first solenoid valve 41A and the second solenoid valve 42 does not rise to the operating pressure of the quick release valve 46. Even if the air pressure equal to or lower than the operating pressure is slowly applied to the quick release valve 46, the control pressure signal does not rise to the operating pressure because the air pressure leaks into the release circuit 39.

(7) The air pressure 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 smaller than the operating pressure is given to the air pressure signal, the quick release valve 46 is opened to the atmosphere, and therefore the parking brakes of the tractor and trailer do not become released.

(Third embodiment)

A third embodiment embodying an air supply circuit will be described with reference to fig. 3. The present embodiment is a system for a tractor (bicycle) when the tractor is not towed, and differs from the first embodiment mainly in that the signal circuit 60B does not have the third electromagnetic valve 43.

As shown in fig. 3, in the present embodiment, the air supply circuit 10 includes a supply flow path 50 and a signal circuit 60B for transmitting an air pressure signal, as in the first embodiment.

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 13 th port P13 and the release circuit 39. The first circuit 61 is a first circuit from the 13 th port P13 to the first solenoid valve 41, the second circuit 62 is a second circuit from the first solenoid valve 41 to the check valve 45, the fourth circuit 64 is a third circuit from the check valve 45 to the second solenoid valve 42, and the second solenoid valve 42 is connected to the release circuit 39. The third circuit 63 in the first embodiment is not provided in this embodiment. A signal air pressure sensor 47 that detects air pressure is connected to the fourth circuit 64. The fourth circuit 64 branches off from the fifth circuit 65. The fifth circuit 65 is connected to the relay valve 40 and to the release valve 101 via a 101 th port P101.

The air supply circuit 10 of the present embodiment does not include the mechanism of the first embodiment for releasing only the parking brake of the trailer for inspection. Therefore, the operation of the air supply circuit 10 is the same as the operation when the third electromagnetic valve 43 is closed and no inspection is performed in the first embodiment, and therefore, the description thereof is omitted.

According to the present embodiment, the following effects can be obtained in addition to the effects (1) to (4) described in the first embodiment.

(8) In a tractor (a bicycle) when the tractor is not towed, the structure of the air supply circuit 10 can be made simpler than that of the air supply circuit 10 in a tractor when the tractor is towed.

(Fourth embodiment)

A fourth embodiment embodying an air supply circuit will be described with reference to fig. 4. The present embodiment differs from the second embodiment in a mode for a tractor (bicycle) when the tractor is not towed.

As shown in fig. 4, in the present embodiment, the air supply circuit 10 includes a supply flow path 50 and a signal circuit 60C for transmitting an air pressure signal, as in the first embodiment.

The signal circuit 60C is different from the signal circuit 60A of the second embodiment in that: the third solenoid valve 43 is not provided, the branch circuit 63A is not provided, and instead, the quick release valve 46 is connected to a middle portion of the fifth circuit 65 branched from the fourth circuit 64.

In detail, the signal circuit 60C includes the first solenoid valve 41 and the second solenoid valve 42 between the 13 th port P13 and the release circuit 39. The first circuit 61 is provided from the 13 th port P13 to the first solenoid valve 41, the fourth circuit 64 is provided from the first solenoid valve 41 to the second solenoid valve 42, and the second solenoid valve 42 is connected to the release circuit 39. The signal air pressure sensor 47 is connected to the fourth circuit 64. The fifth circuit 65 branches off from the fourth circuit 64. In the fifth circuit 65, a quick release valve 46 is connected between the relay valve 40 and the 101 st port.

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

The air supply circuit 10 of the present embodiment does not include the mechanism of the second embodiment for releasing only the parking brake of the trailer for inspection. Therefore, the operation of the air supply circuit 10 is substantially the same as that when the third solenoid valve 43 is closed and no check is performed in the second embodiment, except for the relationship between the quick release valve 46 and the fifth circuit 65.

The case where the ECU 21 loses power when the parking brake is in the on state will be described.

First, when the parking brake is in the on state, the ECU 21 closes the first solenoid valve 41A, and opens the second solenoid valve 42 or closes the second solenoid valve after opening to the atmosphere. Thereby, the fourth circuit 64 is connected to the release circuit 39, and the air pressure signal is kept at the atmospheric pressure. The air pressure signal of the atmospheric pressure deactivates the relay valve 40, and compressed air is not supplied from the second flow path 52, the third flow path 53, and the fourth flow path 54 to the brake chambers, so the brake chambers activate the parking brakes.

After that, when the ECU 21 loses power, since the first electromagnetic valve 41A is always supplied with compressed air from the gas tank 13 even if it is closed, the compressed air may leak into the fourth circuit 64 due to deterioration of the valve or the like. At this time, the quick release valve 46 releases air of a pressure lower than the predetermined pressure applied from the fourth circuit 64 to the release circuit 39. Therefore, even if the 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 concern that the parking brake in operation will be released by the operation of the relay valve 40.

First, when the parking brake is released, the ECU 21 opens the first solenoid valve 41A and closes the second solenoid valve 42. Thereby, an air pressure signal based on the air pressure of the compressed air from the air tank 13 is held in the fourth circuit 64, and the air pressure signal of the fourth circuit 64 operates the relay valve 40 via the quick release valve 46 and the fifth circuit 65. 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 to release the parking brake.

Thereafter, when the ECU 21 loses power, both the first solenoid valve 41A and the second solenoid valve 42 are closed to become off, and the air pressure immediately before the loss of power is maintained in the fourth circuit 64 interposed between the first solenoid valve 41A and the second solenoid valve 42. At this time, communication between the upstream and downstream of the fifth circuit 65 by the quick release valve 46 based on the air pressure signal of the fourth circuit 64 is also maintained. Accordingly, the relay valve 40 that receives the air pressure signal from the fourth circuit 64 via the fifth circuit 65 is maintained open, so that the released state of the parking brake of the tractor is maintained.

According to the present embodiment, the following effects can be obtained in addition to the effects (1) to (4) described in the first embodiment and the effects (6) and (7) described in the second embodiment.

(9) In a tractor (a bicycle) when the tractor is not towed, the structure of the air supply circuit 10 can be made simpler than the structure of the air supply circuit 10 in a tractor when the tractor is towed.

(Fifth embodiment)

A fourth embodiment of embodying the air supply circuit will be described with reference to fig. 5. The present 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 maintained open and closed at the time of inspection. The third solenoid valve 43A is a normally closed two-way two-position solenoid valve, and is controlled to be opened/closed via a wiring E64. The third solenoid valve 43A is disposed at a sealing position shown in fig. 5 when closed, and is disposed at a communication position when open. The third solenoid valve 43A cuts off communication between the third circuit 63 and the fourth circuit 64 in the sealing position, and communicates the third circuit 63 with the fourth circuit 64 in the communication position.

The check valve 45A provided in the signal circuit 60 is a spring-loaded check valve for preventing the air leaking from the normally closed first solenoid valve 41 from flowing, thereby preventing the air pressure of the air pressure signal of the relay valve 40 from rising.

The operation of the air supply circuit 10 will be described.

First, when the parking brake is changed from the on state (open state) to the off state (closed state), the ECU 21 opens the first solenoid valve 41 and the third solenoid valve 43A, and closes the second solenoid valve 42. Thereby, the air pressure signal based on the air pressure of the compressed air from the air tank 13 is held in the second, third, and fourth circuits 62, 63, 64, and the air pressure signal of the fourth circuit 64 operates the relay valve 40 via the fifth circuit 65. The relay valve 40 supplies the 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 of the third circuit 63 by the signal air pressure sensor 47, and detects the air pressures of the third flow path 53 and the fourth flow path 54 by 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 the respective target pressures, the ECU 21 closes the first solenoid valve 41 and closes the second solenoid valve 42 to maintain the air pressure signals of the second to fifth circuits 62 to 65, thereby maintaining the parking brake in the released state. The air pressure signals of the second to fifth circuits 62 to 65 are set to the atmospheric pressure by opening the second solenoid valve 42 and the third solenoid valve 43A in a state where the first solenoid valve 41 is closed, whereby the air pressures of the second flow path 52, the third flow path 53, and the fourth flow path 54 are set to the atmospheric pressure, and the parking brake is set to an operating state. On the other hand, when the detected pressure of either one of the signal air pressure sensor 47 and the supply air pressure sensor 48 is smaller than the corresponding target pressure, the ECU 21 opens the first solenoid valve 41 and the third solenoid valve 43A after closing the second solenoid valve 42, so that the compressed air from the air tank 13 is supplied again as an air pressure signal to the second circuit 62, the third circuit 63, and the fourth circuit 64. Accordingly, the air pressures of the second flow path 52, the third flow path 53, and the fourth flow path 54 are adjusted and maintained at the target pressures, and compressed air of a predetermined pressure is supplied to the brake chamber to release the parking brake of the tractor. In addition, compressed air of a target pressure is supplied to the trailer control valve to release the parking brake of the trailer.

Next, when the parking brake is changed from the released state to the activated state, the ECU 21 closes the first solenoid valve 41 and opens the second solenoid valve 42 and the third solenoid valve 43A. Thereby, the third circuit 63 and the fourth circuit 64 are connected with the release circuit 39, so that the air pressure signal is kept at the atmospheric pressure. The air pressure signal of the atmospheric pressure deactivates the relay valve 40, so that the parking brake is not activated by the brake chambers supplied with compressed air from the second flow path 52, the third flow path 53, and the fourth flow path 54. The ECU 21 detects the air pressure of the third circuit 63 by the signal air pressure sensor 47, and detects the air pressures of the third flow path 53 and the fourth flow path 54 by the supply air pressure sensor 48. The ECU 21 confirms whether the detected pressures of the signal air pressure sensor 47 and the supply air pressure sensor 48 are the atmospheric pressures, respectively. The ECU 21 may close the second electromagnetic valve 42 and the third electromagnetic valve 43A when the detected pressure is the 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 the atmospheric pressure, the ECU 21 opens the second solenoid valve 42 and the third solenoid valve 43A to bring them to the atmospheric pressure. Thereby, the air pressure of the third flow path 53 and the fourth flow path 54 is maintained at the atmospheric pressure. Thus, the brake chamber is maintained at atmospheric pressure, thereby operating the parking brake of the tractor. In addition, the air pressure of the trailer control valve is set to the atmospheric pressure, thereby operating the parking brake of the trailer.

In addition, the air supply circuit 10 can release only the parking brake of the trailer for inspection. In the inspection, the ECU 21 first opens the second solenoid valve 42 and the third solenoid valve 43A to put the parking brakes of the tractor and the trailer into an operating state (open). Next, the third solenoid valve 43A is closed to maintain the air pressure in the fourth circuit 64, thereby maintaining the operating state of the parking brake of the tractor. Next, when the first solenoid valve 41 is opened, 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. This releases the parking brake of the trailer, and only the parking brake of the tractor can be checked. During the inspection, even if the power supply is lost, the state in which only the parking brake of the tractor is operated can be maintained. The inspection here is an inspection of whether or not the tractor to which the trailer is connected can be kept in a stopped state on a slope having a gradient of 12% only by the parking brake of the tractor in a state where the parking brake of the trailer is released.

The operation of the present embodiment will be described.

In addition, the ECU 21 may lose power due to disconnection or the like. At this time, it is necessary to maintain the released state or the operating state at the time of the power loss to avoid the operational state of the parking brake from being different from the operation of the driver immediately before the power loss. That is, it is necessary to prevent the parking brake from being switched from the released state to the activated state or from being switched from the activated state to the released state by the ECU 21 losing the power supply. In this regard, according to the present embodiment, even if the ECU 21 loses power due to disconnection or the like, the operating state of the parking brake is maintained in the operating state when the power is lost. In the following, when the inspection of the parking brake of the trailer is not performed, the third solenoid valve 43A, which is normally closed, is opened to communicate the third circuit 63 with the fourth circuit 64.

Immediately before the power is lost, the first solenoid valve 41 is closed, the second solenoid valve 42 is opened or closed after being opened to the atmosphere, so that the second circuit 62, the third circuit 63, and the fourth circuit 64 are all opened to the atmosphere. When power is lost at this time, the normally closed first, second, and third solenoid valves 41, 42, and 43A are all closed to become closed, thereby maintaining the atmospheric pressure immediately before the loss of power in the third and fourth circuits 63 and 64 interposed between the check valve 45A and the second solenoid valve 42. Thus, the relay valve 40, which receives the air pressure signal from the fourth circuit 64, remains off, so that the operating state of the parking brake of the tractor is maintained. In addition, the trailer control valve, which receives the air pressure signal from the third circuit 63, causes the parking brake of the trailer to be maintained in an operating state.

Further, since the compressed air is always supplied from the air tank 13 even when the first electromagnetic valve 41 is closed, there is a possibility that the compressed air leaks to the check valve 45A side due to deterioration of the valve or the like. At this time, the first solenoid valve 41 causes the second circuit 62 on the check valve 45A side to communicate with the release circuit 39, and thus the leaked compressed air is released to the atmosphere, and the pressure on the check valve 45A side is maintained at the atmospheric pressure. The check valve 45A is not opened unless a predetermined valve opening pressure is applied, and thus maintains a closed state. In other words, the air pressure of the third and fourth circuits 63 and 64 is raised by the compressed air leaking out of the first solenoid valve 41 through the check valve 45A, and the relay valve 40 is opened to release the parking brake in operation. Therefore, the air pressure signals of the third circuit 63 and the fourth circuit 64 are maintained at the same atmospheric pressure immediately before the power is lost even after the power is lost, and thus are stable and highly reliable.

Since the parking brake is in the released state, immediately before the power is lost, the first solenoid valve 41 is opened or closed after the pressure is adjusted, the second solenoid valve 42 is closed and the third solenoid valve 43A is opened, so that the third circuit 63 and the fourth circuit 64 are maintained at the prescribed air pressure. When the first solenoid valve 41 and the second solenoid valve 42, which are normally closed by the loss of power at this time, are both closed and turned off, a predetermined air pressure immediately before the loss of power is maintained in the third circuit 63 and the fourth circuit 64 interposed between the check valve 45A and the second solenoid valve 42. Accordingly, the relay valve 40 that receives the air pressure signal of the prescribed air pressure from the fourth circuit 64 is maintained open, so that the released state of the parking brake of the tractor is maintained. In addition, the trailer control valve that receives the air pressure signal from the third circuit 63 maintains the released state of the parking brake of the trailer.

Further, the first solenoid valve 41 communicates the second circuit 62 on the check valve 45A side with the release circuit 39 when closed, but the check valve 45A does not allow air to flow from the third circuit 63 to the second circuit 62, so the air pressure of the third circuit 63 and the fourth circuit 64 does not drop, and there is no concern that the parking brake in the released state will be operated. Therefore, the air pressure signals of the third circuit 63 and the fourth circuit 64 are maintained at the same air pressure immediately before the power is lost even after the power is lost, and thus are stable and highly reliable.

(5) 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 by the operation of the third electromagnetic valve 43A. For example, by cutting off the air pressure signal to the relay valve 40 by the third solenoid valve 43A, only the parking brake of the trailer can be released while the parking brake of the tractor is operated, and only the parking brake of the tractor can be inspected. When described in detail, after the parking brakes of the tractor and trailer are operated, the third solenoid valve 43A is closed, so that compressed air can be supplied to the trailer control valve and compressed air cannot be supplied to the relay valve 40. Thus, the parking brake of the trailer can be released while the parking brake of the tractor is operated.

(10) Since the third electromagnetic valve 43A is a normally closed electromagnetic valve, when the ECU 21 that controls the opening/closing of the electromagnetic valve loses power, even if air leaks from the first electromagnetic valve 41, the application of an air pressure signal to the relay valve 40 can be prevented by the normally closed third electromagnetic valve 43A.

(Other embodiments)

The above embodiments can be modified and implemented as follows. The above embodiments and the following modifications can be combined and implemented within a range that is not technically contradictory.

In the above embodiments, the case where the supply air pressure sensor 48 is provided downstream of the relay valve 40 of 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 has been described. However, the present invention is not limited thereto, and the supply air pressure sensor and the signal air pressure sensor may be provided to either one of them as long as the operation state of the parking brake can be controlled. In addition, if detailed pressure control is not required, control may be performed by time or the like without providing both the supply air pressure sensor and the signal air pressure sensor. This can simplify the structure of the air supply circuit.

In the sixth circuit 66, if there is no quick release valve between the third circuit 63 and the 31 st port P31, a quick release valve may be provided between the third circuit 63 and the 31 st port P31.

In the fifth circuit 65, if there is no 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 air pressure of the third circuit 63 and the fourth circuit 64 is regulated by the first solenoid valve 41 or the second solenoid valve 42, typically by opening the third solenoid valve 43A. On the other hand, when the ECU 21 loses power and closes the second solenoid valve 42 and the third solenoid valve 43A, the air pressure immediately before the loss of power is maintained in the third circuit 63 and the fourth circuit 64, so that the operating states of the parking brake of the tractor and the parking brake of the trailer are maintained. In addition, even if the compressed air from the gas tank 13 leaks at the first solenoid valve 41, the third circuit 63 and the fourth circuit 64 are shut off by the third solenoid valve 43A, and the third circuit 63 is connected to the release circuit 39. Therefore, the air pressure of the third circuit 63 and the fourth circuit 64 is increased by the leaked compressed air, and the parking brake in operation is not likely 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 air pressure of the third circuit 63 and the fourth circuit 64 is regulated by the first solenoid valve 41 or the second solenoid valve 42, typically by opening the fourth solenoid valve 44. On the other hand, when the ECU 21 loses power and the fourth solenoid valve 44 and the second solenoid valve 42 are closed, the air pressure immediately before the loss of power is maintained in the third circuit 63 and the fourth circuit 64, so that the operating states of the parking brake of the tractor and the parking brake of the trailer are maintained. In addition, even if the compressed air from the gas tank 13 leaks at the first solenoid valve 41, the space between the second circuit 62 and the third circuit 63 is shut off by the fourth solenoid valve 44, and the second circuit 62 is connected to the release circuit 39. Therefore, the air pressure of the third circuit 63 and the fourth circuit 64 is increased by the leaked compressed air, and the parking brake in operation is not likely to be released. In the fifth embodiment, the check valve 45 of the signal circuit 60 may be replaced with a fourth electromagnetic valve that is normally closed.

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

As shown in fig. 8, a 31 st port P31 connected to the trailer control valve may be provided in the branch flow path 52A branched from the second flow path 52. In this case, the third electromagnetic valve 43 may be removed from the signal circuit 60 and provided downstream of the branch flow path 52A of the second flow path 52 as the third electromagnetic valve 43B. Since the third solenoid valve 43B is a normally open solenoid valve, both the parking brake of the tractor and the parking brake of the trailer normally operate in accordance with the output of the relay valve 40. Thus, the actuation of the parking brake of the tractor is synchronized with the actuation of the parking brake of the trailer. On the other hand, for inspection, the operation of the parking brake of the tractor and the operation of the parking brake of the trailer can be out of synchronization by closing the third electromagnetic valve 43. For example, the parking brake of the trailer can be released while the parking brake of the tractor is operated.

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 a normally closed solenoid valve, normally, both the parking brake of the tractor and the parking brake of the trailer are operated in accordance with the output of the relay valve 40 by opening the third solenoid valve 43C. Thus, the actuation of the parking brake of the tractor is synchronized with the actuation of the parking brake of the trailer. On the other hand, for inspection, the operation of the parking brake of the tractor and the operation of the parking brake of the trailer can be out of synchronization by closing the third electromagnetic valve 43C. When the ECU 21 loses power and the third solenoid valve 43C is closed, the air pressure immediately before the loss of power is maintained in the third flow path 53 and the fourth flow path 54, and the parking brake of the tractor is maintained in an operating state.

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

As shown in fig. 10, the check valve 45 of the signal circuit 60B in the third embodiment may be replaced with a normally closed fourth solenoid valve 44. The fourth solenoid valve 44 is normally opened to adjust the air pressure of the fourth circuit 64 through the first solenoid valve 41 or the second solenoid valve 42. On the other hand, when the ECU 21 loses power and closes the fourth solenoid valve 44, the air pressure immediately before the loss of power is maintained in the fourth circuit 64 between the fourth solenoid valve 44 and the second solenoid valve 42, so that the operating state of the parking brake of the tractor is maintained. In addition, even if the compressed air from the gas tank 13 leaks at the first solenoid valve 41, the fourth solenoid valve 44 cuts off between the second circuit 62 and the fourth circuit 64, and the second circuit 62 is connected to the release circuit 39. Therefore, the leaked compressed air may raise the air pressure of the fourth circuit 64 to release the parking brake in operation.

In the above embodiments, the description has been made with respect to the air supply circuit 10 being used only for a tractor or for a connected vehicle including a tractor and a trailer. In addition to this, the air supply circuit may be used for other vehicles such as cars and railway vehicles.

Description of the reference numerals

10: An air supply circuit; 13: a gas tank; 21: an ECU;39: a release loop; 40: a relay valve; 41. 41A: a first electromagnetic valve; 42: a second electromagnetic valve; 43. 43B: a third electromagnetic valve; 44: a fourth electromagnetic valve; 45: a one-way valve; 46: a quick release valve; 47: a signal air pressure sensor; 48: a supply air pressure sensor; 39: a release loop; 49: a discharge port; 50: a supply channel; 51: a first flow path; 52: a second flow path; 52A: a branch flow path; 53: a third flow path; 54: a fourth flow path; 60. 60A, 60B, 60C: a signal loop; 61: a first loop; 62: a second loop; 63: a third loop; 63A: a branch circuit; 64: a fourth loop; 65: a fifth loop; 66: a sixth loop; 101: releasing the valve.

Claims

1. An air supply circuit is provided with:

A supply flow path having a relay valve between the gas tank and a brake chamber for parking brake, the supply flow path being configured to supply air;

A signal circuit having a normally closed first solenoid valve and a normally closed second solenoid valve arranged in series between the gas tank and a release circuit open to the atmosphere, the signal circuit for transmitting an air pressure signal; and

A control device for controlling the switching of the opening and closing of the first electromagnetic valve and the switching of the opening and closing of the second electromagnetic valve respectively,

Wherein an air pressure signal between the first solenoid valve and the second solenoid valve is applied to the relay valve as a control pressure signal for controlling the relay valve.

2. The air supply circuit of claim 1, wherein,

There is a release valve that is capable of releasing the control pressure signal applied to the relay valve to the atmosphere.

3. An air supply circuit according to claim 1 or 2, wherein,

An air pressure maintaining mechanism is provided between the first solenoid valve and the relay valve, and is configured so that air pressure from the first solenoid valve is not transmitted to the relay valve when the first solenoid valve is closed.

4. An air supply circuit according to claim 3, wherein,

A check valve is provided in the signal circuit, the check valve allowing air to flow from the first solenoid valve disposed on the tank side to the second solenoid valve disposed on the release circuit side,

The control pressure signal is an air pressure signal between the check valve and the second solenoid valve,

The first solenoid valve is a three-way valve that opens the space between the first solenoid valve and the check valve to the atmosphere when the first solenoid valve is closed.

5. An air supply circuit according to claim 3, wherein,

The signal loop has a quick release valve,

The air pressure signal is applied to the relay valve via the quick release valve as the control pressure signal when the air pressure signal has an air pressure that is greater than or equal to an operating pressure of the quick release valve, and atmospheric pressure is applied to the relay valve via the quick release valve as the control pressure signal when the air pressure signal has an air pressure that is less than the operating pressure of the quick release valve.

6. An air supply circuit according to claim 1 or 2, wherein,

The air supply circuit is connected to the brake chamber of the tractor and to the trailer control valve,

The signal circuit having a third solenoid valve, the signal circuit outputting the air pressure signal to the trailer control valve and applying the air pressure signal to the relay valve via the third solenoid valve,

The air supply circuit supplies compressed air regulated by the relay valve to a brake chamber of the tractor.

7. The air supply circuit of claim 6, wherein,

The third electromagnetic valve is a normally closed electromagnetic valve,

The control device controls switching of opening and closing of the third electromagnetic valve.

8. The air supply circuit of claim 6, wherein,

The air pressure signal is output to the trailer control valve via a quick release valve.