WO2017175820A1

WO2017175820A1 - Emergency operation valve and unloading circuit

Info

Publication number: WO2017175820A1
Application number: PCT/JP2017/014320
Authority: WO
Inventors: 末和郷東
Original assignee: 株式会社タダノ
Priority date: 2016-04-06
Filing date: 2017-04-06
Publication date: 2017-10-12
Also published as: KR101942229B1; JPWO2017175820A1; CN109073111B; CN109073111A; KR20180108837A; JP6219554B1

Abstract

Provided is an emergency operation valve capable of alternatively switching between an open state and a closed state, wherein the emergency operation valve is configured so as to be provided with a valve box having a hollow valve chamber, a first oil channel formed in the valve box as an oil channel for hydraulic oil supplied to the valve chamber, a second oil channel formed in the valve box as an oil channel for hydraulic oil discharged from the valve chamber, a pressure receiver disposed in the valve chamber so as to be capable of shifting between a first position at which the first oil channel communicates with the second oil channel and a second position at which the first oil channel is blocked from the second oil channel, and an elastic member for urging the pressure receiver in a direction toward the first position from the second position.

Description

Emergency operation valve and unload circuit

The present invention relates to an emergency operation valve and an unload circuit. More particularly, the present invention relates to an emergency operation valve and an unload circuit used in a hydraulic working machine such as a truck-mounted crane.

The truck-mounted crane has a mechanical configuration in which a hook suspended by a wire from the tip of a crane boom is wound up and down with a winch, and a hydraulic circuit that drives the winch. Since the hook or boom is damaged if the hook is wound too much, the hydraulic circuit is provided with an unload circuit for stopping the winch drive. A so-called hook overwinding prevention device includes such an unload circuit.

As shown in

Patent Documents

1 and 2, the unload circuit is configured by a relief valve and an electromagnetic on-off valve interposed in a pilot circuit of the relief valve. Such an unload circuit is configured to unload or on-load hydraulic oil by applying / releasing pilot pressure by the electromagnetic on-off valve.
However, the unload circuits of

Patent Documents

1 and 2 constitute an antitheft device and do not constitute an overwinding prevention device for hooks.

The unload circuit 100 constituting the hook overwinding prevention device in the truck-mounted crane will be described with reference to FIG. The hydraulic oil discharged by the hydraulic pump 101 is supplied to each hydraulic actuator through the supply oil passage 102. On the other hand, the hydraulic oil discharged from each hydraulic actuator is returned to the tank 104 through the discharged oil passage 103.

A relief valve 105 is interposed between the supply oil passage 102 and the discharge oil passage 103. The relief valve 105 is closed when the spring pressing force and the pilot pressure are combined, and enters an on-load state in which hydraulic oil flows through the supply oil passage 102. On the other hand, the relief valve 105 is opened when the pilot pressure is exhausted. When the relief valve 105 is opened, the hydraulic oil in the supply oil passage 102 is directly discharged to the discharge oil passage 103 and is in an unloaded state where it is not supplied to each hydraulic actuator.
An electromagnetic on-off valve 106 for switching and controlling the supply / discharge of the pilot pressure is provided.

The truck-mounted crane is provided with a limit switch 109 for detecting over-winding of the hook at the tip of the boom. When the limit switch 109 detects an overwinding of the hook, the electromagnetic on-off valve 106 is opened to release the pilot pressure. Then, the relief valve 105 is opened, and the drive of the winch motor is stopped.

However, when a disconnection occurs in the electrical system that detects overwinding of the hook, the electromagnetic on-off valve 106 is held open by a spring. For this reason, the relief valve 105 also remains open, and the crane cannot be moved.

Therefore, conventionally, as shown in FIG. 7, a manual on-off valve 120 is interposed in series with the electromagnetic on-off valve 106 as an emergency operation valve. When the emergency operation valve 120 is closed, the relief valve 105 is also closed. Then, the hydraulic oil is on-loaded to the supply oil passage 102, and the crane can be moved.

Incidentally, the conventional emergency operation valve 120 is configured as shown in FIG. A pump side passage 122 and a tank side passage 123 are formed in the valve box 121. A valve chamber 124 is formed at a position where the pump side passage 122 and the tank side passage 123 intersect, and a valve body 125 is inserted therein. The valve body 125 is a screw-in type, and a male screw of the valve body 125 meshes with a female screw 126 formed in the valve box 121. Inserting a screwdriver into a concave groove 127 formed in the head of the valve body 125 and rotating it forward and backward to move the valve body 125 forward and backward causes the pump side passage 122 and the tank side passage 123 to communicate with each other or shut off. be able to.

In the emergency operation valve 120, if the valve body 125 is screwed in, the pump side passage 122 and the tank side passage 123 are blocked, and the pilot pressure can continue to be applied to the relief valve 105 shown in FIG. However, since the emergency operation valve 120 is a manual operation, the winch motor can be operated unless it is remembered and released. If the winch motor continues to operate, damage due to overwinding of the hook may occur.

JP 2008-137454 A JP 2009-154740 A

In view of the above circumstances, an object of the present invention is to provide an emergency operation valve that does not forget to be released and an unload circuit using the emergency operation valve.

One aspect of the emergency operation valve according to the present invention is an emergency operation valve that can be selectively switched between a valve open state and a valve closed state, and includes a valve box having a hollow valve chamber, and the valve box. A first oil passage that is formed and supplied to the valve chamber, and a second oil passage that is formed in the valve box and is a hydraulic oil passage that is discharged from the valve chamber; It is arranged in the valve chamber in a displaceable state between a first position where the first oil passage communicates with the second oil passage and a second position where the first oil passage is blocked from the second oil passage. And a resilient member that biases the pressure receiving portion in a direction from the second position toward the first position.

One aspect of the unload circuit according to the present invention is an unload circuit used in a hydraulic circuit of a hydraulic working machine, and is interposed between a supply oil path connected to a pump and a discharge oil path connected to a tank. A relief valve and a pilot pressure control valve for controlling supply and discharge of the pilot pressure to and from the relief valve, and the pilot pressure control valve includes the emergency operation valve described above.

According to one aspect of the vehicle and the unload circuit according to the present invention, the possibility of forgetting to release can be reduced.

It is structure explanatory drawing of the emergency operation valve which concerns on one Embodiment of this invention, Comprising: FIG. 1A is a valve opening state, FIG. 1B is a valve closing state. It is a circuit diagram of the unload circuit concerning one embodiment of the present invention. FIG. 3A is an operation explanatory diagram of the emergency operation valve in the non-operation state, and FIG. 3B is an operation explanatory diagram of the unload circuit when the emergency operation valve is in the non-operation state. 4A is an operation explanatory diagram of the emergency operation valve that is manually pushed, and FIG. 4B is an operation explanatory diagram of the unload circuit in a state where the emergency operation valve is manually pushed. FIG. 5A is an operation explanatory view of the emergency operation valve automatically held, and FIG. 5B is an operation explanatory view of the unload circuit in a state where the emergency operation valve is automatically held. FIG. 6A is an operation explanatory diagram of the emergency operation valve that has automatically returned, and FIG. 6B is an operation explanatory diagram of the unload circuit in a state in which the emergency operation valve has automatically returned. It is a circuit diagram of the conventional unload circuit. It is sectional drawing of the conventional emergency operation valve.

Hereinafter, an emergency operation valve according to an embodiment of the present invention will be described with reference to the drawings.
<1. About emergency operation valve A>
First, the emergency operation valve A will be described with reference to FIG. In FIG. 1, description will be made with the upper direction as one end direction and the lower direction as the other end direction.

First, an outline of the emergency operation valve A will be described. The emergency operation valve according to the present embodiment is an emergency operation valve that can be selectively switched between an open state and a closed state, and has a hollow valve chamber (for example, a valve chamber 12 described later). A box (for example, a valve box 11 to be described later), a first oil path (for example, a pump side passage 17 to be described later) that is formed in the valve box and is an oil path for hydraulic oil supplied to the valve chamber, and the above A second oil passage (for example, a tank side passage 18 to be described later) that is formed in the valve box and is an oil passage for hydraulic oil discharged from the valve chamber and the first oil passage are communicated with the second oil passage. Displacement between a first position (for example, the position of the pressure receiving portion 15 in FIG. 1A) and a second position (for example, the position of the pressure receiving portion 15 in FIG. 1B) that blocks the first oil passage from the second oil passage. A pressure receiving portion (for example, a pressure receiving portion 15 to be described later) disposed in the valve chamber in a possible state, and the first position from the second position. Direction towards the location (e.g., FIG. 1A, upper 1B) includes a resilient member which urges the pressure receiving portion (e.g., later-described spring 16), the.

Next, a specific configuration of the emergency operation valve A will be described. In FIG. 1A, the valve box 11 has a valve chamber 12 formed therein as a cylindrical cavity. A valve body 13 is inserted into the valve chamber 12 so as to be able to reciprocate. In the following description, one side (the upper side of FIGS. 1A and 1B) related to the reciprocation of the valve body 13 is also referred to as a first direction, and the other side (the lower side of FIGS. 1A and 1B) is also referred to as a second direction.

In the following description, the unloaded state of the emergency operation valve A is the opened state of the emergency operation valve A. On the other hand, the on-load state of the emergency operation valve A is a closed state of the emergency operation valve. The unload state of the unload circuit is a state in which hydraulic oil can pass through the relief valve 5 (see FIG. 2) of the unload circuit (that is, the relief valve 5 is opened). On the other hand, the onload state of the unload circuit is a state in which hydraulic oil cannot pass through the relief valve 5 of the unload circuit (that is, the relief valve 5 is closed). Furthermore, the unloaded state of the hydraulic circuit in which the unloaded circuit is incorporated is a state in which hydraulic oil is not supplied to the hydraulic actuator of the hydraulic working machine. On the other hand, the on-load state of the hydraulic circuit incorporating the unload circuit is a state in which hydraulic oil is supplied to the hydraulic actuator of the hydraulic working machine.

The valve element 13 includes a round rod-shaped valve rod 14 and a flange-shaped pressure receiving portion 15 formed at an intermediate portion of the valve rod 14. The pressure receiving portion 15 is a member having a diameter larger than that of the valve rod 14. A pressure receiving surface that receives the pressure of the hydraulic oil is formed on the upper surface of the pressure receiving portion 15 (that is, the surface on the first direction side). On the other hand, a spring-side pressure receiving surface that receives the spring pressure of the spring 16 described later is formed on the lower surface (that is, the surface in the second direction) of the pressure receiving portion 15. When the pressure receiving portion 15 receives the pressure of the hydraulic oil, the valve body 13 is pushed down to the second direction side (the other end side, the lower side in FIG. 1A).

The pressure receiving part 15 divides the valve chamber 12 into two. A space on the valve chamber 12 that is closer to the first direction than the pressure receiving portion 15 (one end side and the upper side in FIGS. 1A and 1B) is referred to as a pressure receiving chamber 12a. On the other hand, a space in the valve chamber 12 that is on the second direction side (lower side in FIGS. 1A and 1B) from the pressure receiving portion 15 is referred to as a spring chamber 12b. That is, the pressure receiving unit 15 partitions the valve chamber 12 into a pressure receiving chamber 12a that is a first chamber and a spring chamber 12b that is a second chamber.

The volume of the pressure receiving chamber 12a and the spring chamber 12b changes according to the reciprocation of the pressure receiving portion 15. As shown in FIG. 1A, in a state where the pressure receiving portion 15 is completely displaced in the first direction of the valve chamber 12, the volume of the pressure receiving chamber 12a is the smallest and the volume of the spring chamber 12b is the largest.

A spring 16 that is an example of an elastic member is disposed in the spring chamber 12b. The upper end of the spring 16 is in contact with the lower surface of the pressure receiving portion 15 (that is, the spring side pressure receiving surface). The lower end of the spring 16 is in contact with the end surface of the inner surface of the valve box 11 in the second direction (the lower side of FIGS. 1A and 1B). In this state, the spring 16 presses and urges the valve body 13 toward the first direction (the upper side in FIGS. 1A and 1B). In addition, the kind of elastic member and the position of an elastic member are not limited to the case of this embodiment.

In the valve box 11, a pump side passage 17 and a tank side passage 18 are formed. The pump side passage 17 is formed between the central portion of the valve chamber 12 and the end portion on the first direction side. In other words, the pump-side passage 17 is located on the second direction side (lower side of FIGS. 1A and 1B) with respect to the pressure receiving portion 15 in a state where the valve body 13 is displaced to the end portion in the first direction by the spring pressure of the spring 16. Side).

The tank side passage 18 is formed at the end of the valve chamber 12 in the second direction (the lower end in FIGS. 1A and 1B). That is, in the state where the valve body 13 is displaced to the end portion in the first direction by the spring pressure of the spring 16, the pump side passage 17 and the tank side passage 18 are in the second direction relative to the pressure receiving portion 15. In other words, the pump-side passage 17 and the tank-side passage 18 communicate with the spring chamber 12 b of the valve chamber 12 in the opened state of the emergency operation valve A. A packing 19 for sealing the valve chamber 12 in a liquid-tight manner is provided between the valve stem 14 and the valve box 11.

As shown in FIG. 1A, when the pressure receiving portion 15 of the valve body 13 is pushed up in the first direction by the spring 16 and is closer to the first direction side (above FIG. 1A) than the pump side passage 17, the pump side The passage 17 and the tank side passage 18 communicate with each other. This state is the open state of the emergency operation valve A.

On the other hand, as shown in FIG. 1B, when the valve body 13 is artificially pushed down and the pressure receiving portion 15 is lowered below the pump side passage 17, the hydraulic oil is supplied to the pressure receiving chamber 12 a through the pump side passage 17. When the pressure receiving chamber 12a is filled with hydraulic oil, the valve body 13 is pushed down by the pressure received by the pressure receiving portion 15. In addition, the operation | movement which pushes down the valve body 13 is not limited to when a person pushes directly. Moreover, the main body which pushes down the valve body 13 is not limited to a person. For example, the valve body 13 may be pushed down mechanically by a computer-controlled robot or the like.

In the state where the valve body 13 is pushed down, the valve body 13 is kept in that position even if the operation of pressing the valve body 13 is stopped (that is, even if the force applied to the valve body 13 is artificially removed). This function is called an automatic holding function. While this automatic holding function is working, the pump side passage 17 and the tank side passage 18 are blocked. This state is the closed state of the emergency operation valve A.

On the other hand, if the hydraulic oil supply to the pump side passage 17 is cut off for some reason (for example, the pump is stopped), there is no force to push down the pressure receiving portion 15, so the valve element 13 is moved to the first direction side by the spring 16 (see FIG. 1B) to return to the state of FIG. 1A. This function is called an automatic return function. When the automatic return is performed, the pump side passage 17 and the tank side passage 18 are brought into a communication state again.

Since the emergency operation valve A of the present invention has the automatic return function as described above, there is an effect that it is possible to prevent forgetting to return to the steady state after the emergency response is completed.

<2. About unload circuit B>
Next, an embodiment in which the emergency operation valve A is applied to an unload circuit of a truck-mounted crane that is an example of a hydraulic working machine will be described. First, the circuit configuration around the unload circuit B will be described with reference to FIG.

FIG. 2 shows a hydraulic pump 1, a hydraulic oil supply oil path 2, a hydraulic oil discharge oil path 3, and a tank 4.
Each actuator for crane is connected to the supply oil passage 2 and the discharge oil passage 3 via an operation valve unit 20. FIG. 2 shows the winch motor 21, the boom hoisting cylinder 22, and the boom telescopic cylinder 23, but there are various other hydraulic actuators that are not shown. In the hydraulic circuit having the basic configuration as described above, the unload circuit B of the present invention is provided between the supply oil passage 2 and the discharge oil passage 3.

Hereinafter, the unload circuit B will be described in more detail. The hydraulic pump 1 uses a vehicle engine or the like as a drive source. When the engine is driven and the power take-off device is ON, the engine power is transmitted to the hydraulic pump 1 and the hydraulic pump 1 enters an operating state. When the power take-off device is turned off or the engine is stopped, the hydraulic pump 1 is stopped.

The supply oil path 2 supplies the hydraulic oil discharged from the hydraulic pump 1 to each hydraulic actuator such as the winch motor 21, the boom hoisting cylinder 22, and the boom telescopic cylinder 23. The hydraulic oil discharged from each hydraulic actuator is returned to the tank 4 through the discharge oil passage 3. The unload circuit B includes an oil passage 7 that connects the supply oil passage 2 and the discharge oil passage 3, and a relief valve 5 interposed in the oil passage 7.

The relief valve 5 includes a pilot circuit 5a that urges in the valve opening direction, and a spring 5b and a pilot circuit 5c that urges in the valve closing direction. Both the pilot circuit 5 a and the pilot circuit 5 c are supplied with pilot pressure from the oil passage 7.

When the pressure Pa of the pilot circuit 5a is smaller than the total pressure Pb obtained by adding the spring pressure of the spring 5b and the pilot pressure of the pilot circuit 5c, the relief valve 5 is closed. When the relief valve 5 is closed, the hydraulic oil is supplied to each hydraulic actuator without being unloaded. Then, the hydraulic working machine operates.

However, when the pressure in the pilot circuit 5c is released and disappears, the pressure Pa and the pressure Pb are balanced and opened (the state of the relief valve 5 shown in FIG. 3B). In this case, the hydraulic oil discharged by the hydraulic pump 1 is returned (that is, unloaded) to the discharge oil passage 3 through the oil passage 7 and the relief valve 5. Therefore, the hydraulic oil is not supplied to each hydraulic actuator, and the hydraulic working machine does not operate.

A pilot control circuit 8 is provided between the pilot circuit 5 c of the relief valve 5 and the drain oil passage 3. In the pilot control circuit 8, an electromagnetic on-off valve 6 and an emergency operation valve A are interposed in series.

Both the electromagnetic on-off valve 6 and the emergency operation valve A can switch between supply and discharge of pilot pressure to the pilot circuit 5c of the relief valve 5. If the pilot pressure is supplied to the pilot circuit 5c of the relief valve 5, the relief valve 5 is closed. On the other hand, when the pilot pressure is released from the pilot circuit 5c, the relief valve 5 is opened. By switching between opening and closing of the electromagnetic switching valve 6 and the emergency operation valve A, the unloading state and the onloading state of the unload circuit B are switched.

The electromagnetic on-off valve 6 is used during normal work and operates based on a signal from the switch 9 of the hook overwinding prevention device. On the other hand, the emergency operation valve A is provided in the pilot control circuit 8 to cope with an emergency when the communication line between the switch 9 and the electromagnetic switching valve 6 is disconnected. Such an emergency operation valve A is manually operated.

<2.1 Operation of unload circuit B>
Hereinafter, the operation of the unload circuit B will be described with reference to FIGS. In the following description, it is assumed that the solenoid on / off valve 6 is not energized due to disconnection or the like, and that the solenoid on / off valve 6 is held open by a spring.

<2.1.1 Non-operation>
FIG. 3A shows a state where the emergency operation valve A is not pushed (in other words, a valve open state). In the opened state of the emergency operation valve A, the pressure receiving portion 15 is located at the end portion in the first direction in the valve chamber 12 by the pressing of the spring 16. The pump side passage 17 and the tank side passage 18 communicate with each other as indicated by an arrow y.

The valve opening state of the emergency operation valve A will be specifically described with reference to FIG. 3A. In the opened state of the emergency operation valve A, the pressure receiving portion 15 is positioned at the end portion of the valve chamber 12 in the first direction (upper side in FIG. 3A) by the pressing of the spring 16, so the volume of the pressure receiving chamber 12a is It is smaller than the pressure receiving chamber 12a in the manual push operation state and the automatic holding state described later.

On the other hand, in the opened state of the emergency operation valve A, the volume of the spring chamber 12b is larger than the pressure receiving chamber 12a in the manual push operation state and the automatic holding state described later.

In the opened state of the emergency operation valve A, the pump side passage 17 and the tank side passage 18 communicate with the spring chamber 12b. Therefore, in the opened state of the emergency operation valve A, the pump side passage 17 and the tank side passage 18 communicate with each other via the spring chamber 12b.

When the emergency operation valve A is in the open state, the emergency operation valve A in the unload circuit B is displayed with a hydraulic symbol, as shown in FIG. 3B, and the pilot control circuit 8 communicates with the drain oil passage 3. . As a result, the pilot pressure is released from the relief valve 5, and the relief valve 5 is opened.

In this case, as shown by an arrow Xa in FIG. 3B, the hydraulic oil enters an unloaded state in which it is sent from the supply oil passage 2 to the discharge oil passage 3 via the oil passage 7 (see FIG. 2). That is, since the hydraulic oil is not supplied to each hydraulic actuator in the unloaded state, each hydraulic actuator of the hydraulic working machine is not driven. This prevents accidents such as overwinding of the hook.

<2.1.2 During manual push operation>
After preventing over-winding of the hook, it is necessary to lower the hook or move the boom to the retracted position. For this reason, it is necessary to put the entire hydraulic circuit in an on-road state. Therefore, the crane operator pushes the valve body 13 of the emergency operation valve A by hand as shown in FIG. 4A. Specifically, the crane operator presses one end (the upper end in FIG. 3A) of the valve rod 14 in the second direction (downward in FIG. 3A).

Then, the pressure receiving portion 15 moves in the second direction together with the valve rod 14, and the emergency operation valve A is in the state shown in FIG. 4A (hereinafter referred to as “valve closed state”). As a result, the pump side passage 17 and the tank side passage 18 are blocked by the pressure receiving portion 15. In addition, the valve body 13 of the emergency operation valve A may be pushed not only directly by hand but also via, for example, a machine.

The valve closing state of the emergency operation valve A will be specifically described with reference to FIG. 4A. In the closed state of the emergency operation valve A, the pressure receiving portion 15 is located at the substantially central portion of the valve chamber 12. In this state, the pump side passage 17 communicates with the pressure receiving chamber 12a. On the other hand, the tank side passage 18 communicates with the spring chamber 12b. Therefore, when the emergency operation valve A is closed, the pump side passage 17 and the tank side passage 18 are not in communication.

When the emergency operation valve A is in the closed state, the emergency operation valve A in the unload circuit B is displayed with a hydraulic symbol as shown in FIG. 4B, and the pilot control circuit 8 is closed. As a result, the pilot pressure from the pilot circuit 5c is applied to the relief valve 5 in addition to the spring pressure, and the relief valve 5 is closed. In this case, as shown by an arrow Xo in FIG. 4B, the hydraulic oil is in an on-load state that is sent from the supply oil passage 2 to each hydraulic actuator. Thereby, the hook can be lowered and the boom can be retracted.

<2.1.3 Automatic holding state>
By the way, when the hook is lowered or the boom is stored, the crane operator needs to operate the crane with the other hand while pressing the emergency operation valve A with one hand.

FIG. 5A shows a state where the crane operator releases his / her hand from the valve body 13 and stops the pushing operation. In this state, since the hydraulic oil pressure flowing into the pressure receiving chamber 12a from the pump side passage 17 pushes down the pressure receiving portion 15 and holds the valve body 13, the pump side passage 17 and the tank side passage 18 are shut off. To be kept. That is, the closed state of the emergency operation valve A is automatically maintained.

In other words, in the state shown in FIG. 5A, a force (hereinafter referred to as a first pressing force) that the pressure receiving portion 15 is pressed in the second direction (downward in FIG. 5A) based on the pressure of the hydraulic oil in the pressure receiving chamber 12a. And the force (hereinafter referred to as the second pressing force) by which the pressure receiving portion 15 is pressed in the first direction (upward in FIG. 5A) based on the elastic force of the spring 16 is balanced. For this reason, the position of the pressure receiving part 15 is maintained at the position shown in FIG. 5A (that is, the second position). In this embodiment, the predetermined condition is that the first pressing force and the second pressing force are balanced.

When the state in which the pilot pressure of the pilot circuit 5c is added to the spring pressure of the spring 5b is held in the relief valve 5, the relief valve 5 is held in the closed state. That is, when viewed in the hydraulic circuit shown in FIG. 5B, the hydraulic oil is sent from the supply oil passage 2 to each hydraulic actuator (see arrow Xo in FIG. 5B), and the on-road state is maintained. Thereby, the crane operator can continue the lowering of the hook and the storing of the boom.

<2.1.4 Automatic return>
The emergency operation valve A according to the present embodiment automatically returns from the closed state to the open state. Hereinafter, automatic return of the emergency operation valve A will be described. The crane operator stops the engine of the vehicle when the boom retracting operation is completed. When the engine stops, the hydraulic pump 1 stops rotating and hydraulic oil is no longer discharged from the hydraulic pump 1. Then, the pressure is released from the pressure receiving chamber 12a of the emergency operation valve A, and the first pressing force becomes smaller than the second pressing force. As a result, as shown in FIG. 6A, the valve body 13 is displaced in the first direction (upward in FIG. 6B) by pressing the spring 16 (that is, the second pressing force). And the pressure receiving part 15 is located in the 1st direction side (above FIG. 6B) rather than the pump side channel | path 17, and the pump side channel | path 17 and the tank side channel | path 18 are connected. Thus, the emergency operation valve A automatically returns from the closed state to the open state.

When the emergency operation valve A automatically returns as described above, the pilot pressure is released from the relief valve 5 and the relief valve 5 is opened. When the relief valve 5 is opened, the hydraulic oil enters an unloaded state in which it flows from the supply oil passage 2 to the discharge oil passage 3 as indicated by an arrow Xa in FIG. For this reason, for example, even when the engine of the vehicle is started and the hydraulic pump 1 is restarted, an unintended movement of the hook or boom can be prevented. This prevents unexpected accidents.

In the above-described embodiment, the unload circuit B is configured using the emergency operation valve A and the electromagnetic on-off valve 6. However, the unload circuit may be configured with only the emergency operation valve A.
Further, the emergency operation valve A according to the present embodiment is not limited to the overwinding prevention device, but is used in an unload circuit incorporated in another device (for example, an overload prevention device) having a function of stopping the operation of the crane. It can also be applied.

<3. About action and effect of this embodiment>
According to the present embodiment, the following operations and effects are achieved.
First, the emergency operation valve A according to the present embodiment automatically returns from the closed state to the open state as described above. Specifically, in the valve-closed state shown in FIGS. 4A and 5A, when hydraulic oil is no longer supplied from the pump-side passage 17 to the pressure receiving chamber 12 a due to the drive stop of the hydraulic pump 1 or the like, the hydraulic oil in the pressure receiving chamber 12 a The pressure received by the pressure receiving portion 15 decreases. Then, the valve body 13 (specifically, the pressure receiving portion 15) is displaced from the valve-closed position by the spring 16 in the first direction (above FIGS. 4A and 5A). As a result, the pressure receiving portion 15 is displaced to the end portion in the first direction of the valve chamber 12 (the upper end portion in FIGS. 4A and 5B), and the pump side passage 17 and the tank side passage 18 communicate with each other via the spring chamber 12b. . That is, the emergency operation valve A returns to the valve open state shown in FIG. 6A without operating the valve body 13 by artificial force. As described above, the emergency operation valve A of the present embodiment automatically returns from the closed state to the open state, so that the emergency operation valve A is not forgotten to be released.

Further, the unload circuit B according to the present embodiment includes the emergency operation valve A as described above. For this reason, when the hydraulic pump 1 stops as the engine of the hydraulic working machine stops, the emergency operation valve A automatically returns from the closed state to the opened state. With such an automatic return of the emergency operation valve A, the hydraulic circuit incorporating the unload circuit B is switched from the on-load state to the unload state. Thus, according to the unload circuit B according to the present embodiment, since the forgetting to release the emergency operation valve A does not occur, the hydraulic working machine does not operate without permission and an accident can be prevented.

<4. Addendum>
As a reference example of an emergency operation valve, an emergency operation valve for selectively switching an oil passage between a valve open state and a valve closed state includes a valve box, a hollow valve chamber formed in the valve box, and a valve chamber. A valve body inserted in a reciprocating manner, a spring that presses and biases the valve body toward one end of the valve chamber, a pump-side passage that is formed in the valve box and communicates with one end side of the valve chamber, and a valve chamber A tank side passage that communicates with the other end of the valve body, and the valve body has a pressure receiving portion that generates a force in a direction to push back the spring in response to the hydraulic oil pressure flowing in from the pump side passage. When it is artificially pressed against the spring against the other end, the pressure receiving part shuts off the pump side passage and the tank side passage, and even if the pressing operation is stopped, the state is maintained by the force generated by the pressure receiving part. When the pressure is lost, the valve body is pushed back to one end by a spring, and the pump side passage and tank side A road can be configured so as to communicate.

According to the reference example of the emergency operation valve described above, when the valve body is artificially pressed against the spring, the pressure receiving portion receives the pressure of the hydraulic oil supplied from the pump side passage and the valve body compresses the spring. Since the state is maintained, the pump-side passage and the tank-side passage can be kept in a closed state even if the pressing operation is stopped. Further, while the pressure receiving portion of the valve body receives the hydraulic oil pressure, the pump side passage and the tank side passage can be automatically kept in a state of being shut off even if the artificial pushing operation is stopped. When the hydraulic oil is no longer supplied from the pump side passage for reasons such as stopping the drive of the pump, the pressure received by the pressure receiving portion decreases and the valve body is biased by the spring force, so that the pump side passage and the tank side passage communicate with each other. To return automatically. For this reason, forgetting to release the emergency operation valve does not occur.

In addition, as Reference Example 1 of the unload circuit, a relief valve in which an unload circuit in a hydraulic circuit of a hydraulic working machine is interposed between a supply oil passage connected to a pump and a discharge oil passage connected to a tank, and a relief valve The pilot pressure control valve that controls the supply and discharge of the pilot pressure may be used, and the pilot pressure control valve may be configured using the emergency operation valve of the reference example described above.

According to the reference example 1 of the unload circuit described above, when the emergency operation valve is pushed to keep the pump side passage and the tank side passage shut off, the relief valve receives the pilot pressure and keeps the shut off state. Is supplied to the hydraulic working machine side, the hydraulic working machine operates normally. When the engine of the hydraulic working machine is stopped, the pump is also stopped and the pressure in the pump side passage disappears, so that the valve body of the emergency operation valve is energized by a spring and the pump side passage and the tank side passage To communicate. As described above, since the forgetting to return the emergency operation valve does not occur, the hydraulic working machine does not operate without permission and an accident can be prevented.

Further, as Reference Example 2 of the unload circuit, in the unload circuit of Reference Example 1 described above, the pilot pressure control valve is composed of an electromagnetic open / close valve and a manual open / close valve that are interposed in series with the pilot circuit, The on-off valve may be the emergency operation valve of the reference example described above.

According to the above-described reference example 2 of the unload circuit, in the normal state, the opening / closing of the relief valve is controlled by the electromagnetic opening / closing valve to prevent over-winding of the hook, but the electric system connected to the electromagnetic opening / closing valve is disconnected. When a failure occurs, the opening and closing of the relief valve is controlled by a manual emergency operation valve. In addition, even if the emergency operation valve is forgotten to be released, the hydraulic working machine does not operate without permission, thus preventing an accident.

The disclosure of the specification, drawings, and abstract included in the Japanese application of Japanese Patent Application No. 2016-076332 filed on Apr. 06, 2016 is incorporated herein by reference.

DESCRIPTION OF SYMBOLS 1 Hydraulic pump 2 Supply oil path 3 Discharge oil path 5 Relief valve 6 Electromagnetic on-off valve 8 Pilot control circuit 11 Valve box 12 Valve chamber 13 Valve body 14 Valve rod 15 Pressure receiving part 16 Spring 17 Pump side path 18 Tank side path A Emergency operation Valve B Unload circuit

Claims

An emergency operation valve that can be selectively switched between a valve open state and a valve closed state,
A valve box having a hollow valve chamber;
A first oil passage that is formed in the valve box and is an oil passage for hydraulic oil supplied to the valve chamber;
A second oil passage that is formed in the valve box and is an oil passage for hydraulic oil discharged from the valve chamber;
Disposed in the valve chamber in a displaceable state between a first position where the first oil passage communicates with the second oil passage and a second position where the first oil passage is blocked from the second oil passage. Pressure receiving part,
An elastic member biasing the pressure receiving portion in a direction from the second position toward the first position,
Emergency operation valve.
The valve chamber is partitioned into a first chamber and a second chamber by the pressure receiving portion, the first oil passage communicates with the first chamber in a state where the pressure receiving portion is in the second position, and The emergency operation valve according to claim 1, wherein the second oil passage communicates with the second chamber.
The emergency operation valve according to claim 2, wherein the first oil passage and the second oil passage communicate with the second chamber in a state where the pressure receiving portion is in the first position.
4. The emergency according to claim 2, wherein when the hydraulic pressure of the hydraulic oil in the first chamber and the elastic force of the elastic member satisfy a predetermined condition, the position of the pressure receiving portion is maintained at the second position. 5. Operation valve.
When the hydraulic pressure of the hydraulic fluid in the first chamber and the elastic force of the elastic member no longer satisfy the predetermined condition, the pressure receiving portion is moved from the second position based on the elastic force of the elastic member. The emergency operation valve according to claim 4, which is displaced to one position.
The emergency operation valve according to any one of claims 1 to 5, wherein the pressure receiving portion can be displaced from the first position to the second position by an artificial force.
An unload circuit used in a hydraulic circuit of a hydraulic working machine,
A relief valve interposed between a supply oil passage connected to the pump and a discharge oil passage connected to the tank;
A pilot pressure control valve for controlling supply and discharge of pilot pressure to the relief valve,
The pilot pressure control valve is configured to include the emergency operation valve according to any one of claims 1 to 6.
Unload circuit.
The pilot pressure control valve is composed of an electromagnetic on-off valve and a manual on-off valve interposed in series with a pilot circuit,
The manual on-off valve is the emergency operation valve;
The unload circuit according to claim 7.