JP6859411B2 - Speed-up valve device - Google Patents

Description

The present invention relates to a speed-increasing valve device that increases the extension speed of a rod of a double-acting hydraulic cylinder.

Conventionally, there is known a speed-increasing valve device having a speed-increasing circuit for increasing the extension speed of a rod of a double-acting hydraulic cylinder (hereinafter, also simply referred to as “cylinder”) (see, for example, Patent Document 1). This type of speed-increasing circuit accelerates the rod extension speed by regenerating the pressure oil from the rod side that returns to the tank when the rod is extended to the head side.

Japanese Unexamined Patent Publication No. 2011-21625

However, although this type of speed-increasing circuit increases the extension speed of the rod by increasing the supply flow rate to the head side, when increasing the extension speed of the rod, the oil pressure on the head side and the rod side is increased. Is almost the same pressure. Therefore, there is a problem that the flood pressure acting on the extension operation works only for the cross-sectional area on the rod side, and the original thrust of the cylinder cannot be sufficiently obtained.
In particular, in a double-acting hydraulic cylinder for expanding and contracting the boom of a crane, when this type of speed-increasing circuit is adopted for the boom expansion and contraction mechanism, a crane having a speed-increasing valve device is compared with a crane not equipped with the speed-increasing valve device. Depending on the load on the cylinder due to the suspended load, the crane equipped with the speed-increasing valve device may not be able to obtain the required cylinder thrust and may not be able to extend, so the performance must be lowered. Therefore, there is room for consideration in efficiently performing the crane work according to the magnitude of the load of the suspended load.

Therefore, the present invention has been made by paying attention to such a problem, and provides a speed-increasing valve device capable of appropriately switching the speed-increasing circuit according to the magnitude of the load carried by the double-acting hydraulic cylinder. Is the subject.

In order to solve the above problems, the speed-increasing valve device according to one aspect of the present invention accelerates the extension speed of the rod by regenerating the pressure oil from the rod side of the double-acting hydraulic cylinder to the head side. A speed-up valve device having a speed-up circuit, a controller for determining the magnitude of the load carried by the double-acting hydraulic cylinder, and the speed-up circuit having the speed-up circuit and based on a control signal from the controller. The controller includes a speed-increasing valve having a circuit switching valve for switching, and when the controller determines that the load is less than a predetermined value, it sends a control signal for speed mode to the circuit switching valve, and when it determines that the load is equal to or more than a predetermined value. , The control signal for the normal mode is sent to the circuit switching valve, and when the control signal is for the speed mode, the circuit switching valve opens the speed-up circuit and the speed is increased. When the rod is extended and the control signal is for the normal mode, the circuit switching valve interrupts the speed-increasing circuit and extends the rod at a normal speed.

According to the speed-increasing valve device according to one aspect of the present invention, when the controller determines the magnitude of the load carried by the double-acting hydraulic cylinder and determines that the load is less than a predetermined value (because the thrust of the cylinder may be small). ,) The controller sends a control signal for speed mode to the circuit switching valve of the speed-increasing valve, which opens the speed-increasing circuit and extends the rod at the accelerated speed.
On the other hand, when the controller determines that the load is more than the specified value, the controller sends a control signal for normal mode from the controller to the circuit switching valve of the speed-increasing valve (because the thrust of the cylinder is required), and the speed-up valve increases. The speed circuit is cut off and the rod is extended at normal speed.

Therefore, according to the speed-increasing valve device according to one aspect of the present invention, it is possible to determine whether or not there is a load carried by the double-acting hydraulic cylinder and appropriately switch the speed-increasing circuit.
Here, in the speed-increasing valve device according to one aspect of the present invention, a load meter for detecting the load carried by the double-acting hydraulic cylinder is further provided, and the double-acting hydraulic cylinder is for driving a crane. It is preferable that the load gauge is provided so that the magnitude of the load carried by the double-acting hydraulic cylinder can be detected.

Further, if the load gauge is provided so as to be able to detect the presence or absence of a suspended load on the crane, for example, the controller controls the circuit switching valve based on the presence or absence of a suspended load on the crane, and the suspended load is released. When it is determined that there is no load, it is preferable to send a control signal for speed mode to the circuit switching valve, and when it is determined that there is a suspended load, it is preferable to send a control signal for normal mode to the circuit switching valve.

Such a configuration is suitable for adopting the speed-increasing valve device according to one aspect of the present invention in a crane, and depending on whether the operator operating the crane is before or after suspending the load. Crane work can be performed efficiently.
Further, in the speed-increasing valve device according to one aspect of the present invention, it is preferable that the speed-increasing valve is configured by using a check valve in the speed-increasing circuit. Further, in the speed-increasing valve device according to one aspect of the present invention, it is preferable that the speed-increasing valve is configured by using a spool in the speed-increasing circuit.

As described above, according to the present invention, the speed increasing circuit can be appropriately switched according to the magnitude of the load carried by the double-acting hydraulic cylinder.

It is a circuit diagram explaining the 1st Embodiment of the speed-increasing valve device which concerns on one aspect of this invention. It is a figure which represented the structure of the part of the speed-increasing valve of FIG. 1 schematically. It is a flowchart of the speed-up operation control process executed by the controller of FIG. It is a circuit diagram ((a), (b)) explaining the second embodiment of the speed-increasing valve device which concerns on one aspect of this invention, and FIG. (B) shows the case where the detected value is less than the threshold value. It is a figure ((a), (b)) schematically showing the structure of the part of the speed-increasing valve of FIG. 4, and (a) is a figure (a) when the detection value of a load meter is equal to or more than a threshold value, (b) is The case where the detected value is less than the threshold value is shown. It is a reference figure explaining an example of the hydraulic circuit of a double-acting hydraulic cylinder. It is a reference figure explaining an example of the hydraulic circuit which has a speed-increasing valve.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate. The drawings are schematic. Therefore, it should be noted that the relationship, ratio, etc. between the thickness and the plane dimension are different from the actual ones, and the drawings include parts where the relationship and ratio of the dimensions are different from each other. Further, each embodiment shown below exemplifies an apparatus or method for embodying the technical idea of the present invention, and the technical idea of the present invention describes the material, shape, structure, and the like of the component parts. The arrangement and the like are not specified in the following embodiments.

Here, each embodiment shown below is an example in which the speed-increasing valve device of the present invention is used for the boom expansion / contraction mechanism of a crane mounted on a work vehicle such as a truck. The speed-increasing valve device of each embodiment is set as the extension operation speed of the rod of the boom expansion / contraction cylinder to a speed mode in which the extension operation is performed faster than usual and a normal mode in which the extension operation is performed by a normal crane. It is possible. Then, the speed-increasing valve device of each embodiment controls the speed-increasing valve by a controller, and shifts to the speed mode when the load is small and shifts to the speed mode when the load is large, depending on the magnitude of the load carried by the boom expansion / contraction cylinder. It is designed to shift to normal mode. This will be described in detail below.

[First Embodiment]
As shown in FIG. 1, the speed-up valve device 1 of the first embodiment includes a load meter 2, a controller 3, and a speed-up valve 20. The speed-increasing valve 20 is provided between the boom expansion / contraction cylinder 10 and the control valve 4 for the boom expansion / contraction cylinder 10.
The boom expansion / contraction cylinder 10 is a double-acting hydraulic cylinder for expanding / contracting the boom of a crane. A piston 15 is slid into a cylindrical tube 14, and a contraction chamber 11 and an extension chamber 12 are defined before and after the piston 15. Has been done. The rod 13 integrated with the piston 15 projects from the contracted chamber 11 side.

The control valve 4 has a first service port B1, a second service port A1, a pump port P, and a tank port T. The first service port B1 is connected to the extension chamber 12 of the boom expansion / contraction cylinder 10 from the extension circuit 27 in the speed-increasing valve 20 via the first oil passage 7. Further, the second service port A1 is connected to the contraction chamber 11 of the boom expansion / contraction cylinder 10 from the contraction circuit 29 in the speed-increasing valve 20 via the second oil passage 8. The control valve 4 is arranged in a control valve (not shown) that controls the supply and discharge of pressure oil for the entire crane, and the supply and discharge of required pressure oil is controlled according to the amount of operation of the crane.

When the speed-increasing valve 20 is not taken into consideration in the hydraulic circuit of the boom expansion / contraction cylinder 10 (see FIG. 6), the pressure oil from the first service port B1 extends the chamber when the rod 13 of the boom expansion / contraction cylinder 10 is extended. Upon entering 12, the pressure oil in the contracted chamber 11 is discharged from the second service port A1 to the tank port T of the control valve 4, and the rod 13 is extended. Further, when the rod 13 is reduced, the pressure oil from the second service port A1 enters the contraction chamber 11, and the pressure oil in the extension chamber 12 is discharged from the first service port B1 to the tank port T of the control valve 4. The rod 13 is configured to be reduced.

Here, as described with reference to FIG. 1, the speed-increasing valve 20 of the speed-increasing valve device 1 includes a contraction circuit 27 that communicates with the extension chamber 12 side of the boom expansion / contraction cylinder 10 and a contraction circuit 29 that communicates with the contraction chamber 11 side. It has a speed-up circuit 20k connected to each other and a circuit switching valve 24 for switching the oil passage to the speed-up circuit 20k side.
As shown in FIG. 2, the speed-increasing valve 20 of the present embodiment has a valve body 28 unitized in a block shape. A circuit switching valve 24 for switching the speed-increasing circuit 20k is mounted on one side surface (lower surface in the figure) of the valve body 28. Further, on the left and right side surfaces of the valve body 28, a connection port communicating with the first service port B1 via the first oil passage 7 and the extension circuit 27, and the second oil passage 8 and the contraction circuit 29 are provided. A connection port communicating with the second service port A1 is formed.

Three check valves 21, 22, and 23 are provided inside the valve body 28. In the present embodiment, the first check valve 21 of the three check valves is interposed in the contraction circuit 29, and the second check valve 22 and the third check valve 23 are interposed in the speed-increasing circuit 20k. ..
The first check valve 21 is provided on the circuit of the contraction circuit 29, and normally allows only the flow of pressure oil entering the contraction chamber 11 from the second service port A1 of the control valve 4, and the circuit switching valve 24 When the pilot pressure is received from the above, the oil passage A → B is opened so that the pressure oil discharged from the contracted chamber 11 can be discharged to the tank port T.

The second check valve 22 is provided between the third check valve 23 and the contraction circuit 29 on the circuit of the speed-increasing circuit 20k. The second check valve 22 is normally closed so that the pressure oil from the contracted chamber 11 side does not flow, and the oil passage C → D is opened when the pilot pressure from the circuit switching valve 24 is received. There is.
The third check valve 23 is provided at a position on the extension circuit 27 side of the speed-increasing circuit 20k, and is interposed so as to allow only the flow of pressure oil from the contraction chamber 11 side to the extension chamber 12 side.

The load cell 2 is composed of, for example, a load cell, and is attached to a boom of a crane (not shown) so that the magnitude of the load carried by the rod 13 of the boom expansion / contraction cylinder 10 can be detected.
The controller 3 is a control device including a computer (not shown) and a power module for output, and is configured to be able to acquire the detected value of the load meter 2. The controller 3 executes the program of the speed-up operation control process shown in FIG. 3, determines the magnitude of the load based on the detected value of the load meter 2, and is configured to be able to control the speed-up valve 20. The speed-up operation control process is executed in parallel with the main process as an interrupt process of the process of the main program by starting the crane.

Specifically, the speed-up operation control process is executed at the time of the extension operation of the rod 13, and when the speed-up operation control process is executed, the controller 3 loads the load in step S1 as shown in FIG. A total of 2 detection values are acquired, and the process proceeds to step S2. In step S2, it is determined whether or not there is an extension operation of the rod 13 based on the operation input, and if there is no operation, the process returns to step S1, and if the operation is performed, the process proceeds to step S3. In step S3, the detected value is compared with the preset threshold value based on the acquired detected value of the load meter 2. Here, the threshold value is a preset predetermined value indicating a switching point between the speed mode and the normal mode.

In step S3, when the controller 3 determines that the detected value of the load meter 2 is less than the threshold value, the controller 3 proceeds to step S4, and in step S4, the speed mode transition process is executed and the process returns to step S1. The speed mode transition process is a series of processes for sending a control signal for the speed mode to the circuit switching valve 24 of the speed increasing valve 20.
On the other hand, when the controller 3 determines that the detected value of the load meter 2 is equal to or greater than the threshold value, the controller 3 proceeds to step S5, and in step S5, the normal mode transition process is executed and the process returns to step S1. The normal mode transition process is a series of processes for sending the control signal for the normal mode to the circuit switching valve 24 of the speed-increasing valve 20.

When the control signal received from the controller 3 is for the speed mode, the circuit switching valve 24 of the speed-increasing valve 20 opens the speed-up circuit 20k to accelerate the speed of the rod 13 during the extension operation of the rod 13. When the control signal is for the normal mode, the speed increasing circuit 20k is shut off during the extension operation of the rod 13, the first check valve 21 is opened, and the pressure oil is returned to the tank 6. The rod 13 is extended at a normal speed.

More specifically, when the controller 3 determines that the detected value of the load meter 2 is equal to or higher than the threshold value during the extension operation of the rod 13, the controller 3 sends a control signal for the normal mode to the solenoid of the circuit switching valve 24. In the present embodiment, the control signal is a solenoid drive signal, and the normal mode control signal is a case where the solenoid drive signal is “non-energized”.
When the drive signal from the controller 3 is not energized, no current flows through the solenoid of the circuit switching valve 24, and the pilot circuit of the circuit switching valve 24 does not flow pilot oil through the control port Y and pilots through the control port X. Run the oil (state shown in FIG. 1). As a result, the pilot oil flows to the control port X of the circuit switching valve 24 along with the extension operation of the rod 13, so that the first check valve 21 opens, but at this time, the second check valve 22 remains closed. There is. Therefore, in the normal mode, the pressure oil discharged from the contraction chamber 11 returns to the tank 6 through the contraction circuit 29 without flowing to the speed increasing circuit 20k.

On the other hand, when the controller 3 determines that the detected value of the load meter 2 is less than the threshold value during the extension operation of the rod 13, the controller 3 sends a control signal for the speed mode to the circuit switching valve 24. In the present embodiment, the control signal for the speed mode is a case where the drive signal of the solenoid is "energized", and the current required for driving the solenoid is energized via the power module.
When the solenoid drive signal is output from the controller 3, a current flows through the solenoid of the circuit switching valve 24, pilot oil flows through the control port Y, and the second check valve 22 is opened. At this time, the pilot oil does not flow to the control port X, and the first check valve 21 is closed. As a result, in the speed mode, the pressure oil from the contraction chamber 11 is pumped to the extension chamber 12 side through the oil passage C → oil passage D → oil passage E → oil passage F inside the speed increasing circuit 20k in this order. The extension speed of the rod 13 is increased while merging with the pressure oil discharged from 5.

Next, the operation of the speed-increasing valve device 1, the expansion / contraction operation of the rod of the boom expansion / contraction cylinder accompanying the operation, and the action / effect will be described.
First, when the rod 13 of the boom expansion / contraction cylinder 10 is reduced and operated, the pressure oil from the second service port A1 enters the contraction chamber 11 via the first check valve 21 of the speed-increasing valve 20 and expands the chamber. The pressure oil of 12 is discharged from the first service port B1 to the tank port T of the control valve 4, and the rod contracts.

On the other hand, when the rod 13 of the boom expansion / contraction cylinder 10 is extended, the controller 3 switches the speed-increasing valve 20 to either the speed mode or the normal mode based on the detected value of the load meter 2.
When the controller 3 determines that the detected value of the load meter 2 is less than the threshold value, the speed-increasing valve device 1 of the present embodiment sends a control signal for speed mode to the circuit switching valve 24 during the extension operation of the rod 13. The circuit switching valve 24 opens the speed-increasing circuit 20k, regenerates and supplies the pressure oil discharged from the contraction chamber 11 to the extension chamber 12, and shifts to a speed mode in which the speed-up extension operation is performed.

The amount of pressure oil discharged from the contracted chamber 11 is 13 minutes for the rod existing in the contracted chamber 11 and the amount of outflow is smaller than the amount of pressure oil flowing into the expansion chamber 12, so that the amount of pressure oil discharged from the contracted chamber 11 is on the expansion chamber 12 side only momentarily at the time of discharge. Due to the boost effect that makes the pressure higher than that of the pressure oil, it smoothly joins the pressure oil on the extension chamber 12 side. As a result, in the speed mode, the pressure oil on the contraction chamber 11 side is regenerated to the extension chamber 12 side, so that the rod 13 of the boom expansion / contraction cylinder 10 is accelerated and extended.

Here, FIG. 7 shows a comparative example of the speed-increasing circuit. In the speed-increasing circuit 120 shown in the figure, when the rod 13 is extended, the check valve 122 is opened by the pilot pressure from the pilot oil passage 126, and the pressure oil extruded from the contracted chamber 11 of the cylinder 10 is reused to reuse the cylinder 10. This is a circuit that flows through the first oil passage 7 on the extension chamber 12 side of the above.
As a result, the flow rate sent to the first oil passage 7 on the extension chamber 12 side increases by the amount of oil extruded from the contraction chamber 11. As described above, the speed-increasing circuit 120 of this comparative example sends the pressure oil returning from the contraction chamber 11 side to the extension chamber 12 side without returning to the tank 6, thereby supplying more pressure oil than the supply flow rate to the extension chamber 12. It can be supplied to the side to obtain an extension speed of the rod 13 faster than usual, as in the speed mode of the present embodiment.

However, although the speed-increasing circuit 120 of this comparative example can increase the extension speed of the rod 13 with a small supply flow rate, the oil pressures on the extension chamber 12 side and the contraction chamber 11 side are always the same when the rod is extended. Therefore, when the extension speed of the rod 13 is increased, the flood pressure acts only on the rod cross-sectional area, not on the tube cross-sectional area of the cylinder 10, and the thrust of the rod 13 in the extension direction becomes small. Therefore, in particular, when the rod 13 is extended under a large load, such as when the crane is suspended, the cylinder thrust may be insufficient.

On the other hand, in the speed-up valve device 1 of the present embodiment, when the controller 3 determines that the detected value of the load meter 2 is equal to or higher than the threshold value, the speed-up valve device 1 is transferred to the circuit switching valve 24 of the speed-up valve 20 when the rod 13 is extended. The control signal for the normal mode is sent, and the circuit switching valve 24 closes the speed increasing circuit 20k, discharges the pressure oil from the contracted chamber 11 to the tank port T, and shifts to the normal mode in which the normal extension operation is performed. Let me.
As a result, when the load of the speed-increasing valve device 1 of the present embodiment is large, the pressure oil is not regenerated from the speed-increasing circuit 20k to the extension chamber 12 due to the shift to the normal mode, and the boom expansion / contraction cylinder 10 Although the speed of the rod 13 is not increased, the pressure difference between the front and rear chambers of the cylinder 10 is the difference in the pressure receiving area of the piston portion of the rod 13. Therefore, in the normal mode, the original thrust of the cylinder can be obtained. Therefore, the operator who operates the crane can avoid the situation where the cylinder thrust cannot be obtained and the crane cannot be extended.

Further, a feature of the speed-increasing valve device 1 of the present embodiment is that it does not affect the "occurrence of load shake" due to the circuit pressure. In order to carry out crane work with a stable suspended load, it is extremely important not to cause load shake.
If a general speed-up circuit in which the speed-up circuit is switched depending on the magnitude of the circuit pressure as shown in Patent Document 1 as an example is used, if the circuit pressure of the speed-up circuit is not stable, in the vicinity of the mode switching, Frequent switching between the speed mode and the normal mode makes the operation of the crane unstable, which causes load shake, which reduces the stability of the crane operation. There are various factors that make the circuit pressure unstable, such as the pulsation of the fluid generated during the operation of the crane and the generation of impact pressure, and it is difficult to maintain the stability of the circuit pressure.

On the other hand, in the speed-increasing valve device 1 of the present embodiment, there is no influence of the circuit pressure on the mode switching. When the crane lifts a load with a large load, the work continues while maintaining the normal mode until the load is unloaded, and when the load with a small load is lifted, the speed mode is used. Since the work is performed while holding the crane, once the load is lifted, the mode does not switch during operation. Therefore, it is possible to carry out the work in a stable manner without causing "load shake".

As described above, according to the crane provided with the speed-increasing valve device 1, the speed-increasing circuit 20k can be appropriately switched according to the magnitude of the load carried by the boom expansion / contraction cylinder 10. The speed-increasing valve device according to the present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.
For example, in this speed-increasing valve device 1, the speed-increasing circuit 20k can be switched according to the magnitude of the load carried by the boom expansion / contraction cylinder 10. The speed increasing circuit 20k may be appropriately switched according to the above.

Specifically, when the controller 3 determines that the detected value of the load meter 2 is equal to or higher than the threshold value during the extension operation of the rod 13, the controller 3 sends a control signal for the normal mode to the solenoid of the circuit switching valve 24. However, when there is a suspended load (the detected value of the load meter 2 is larger than 0 (the detected value exceeds the dead zone region)), the control signal for the normal mode is sent to the circuit switching valve 24. ..

Similarly, when the controller 3 determines that the detected value of the load meter 2 is less than the threshold value during the extension operation of the rod 13, the controller 3 sends a control signal for the speed mode to the solenoid of the circuit switching valve 24. When it is determined that there is no suspended load (the detection value of the load meter 2 is 0 (the detection value is less than the dead zone region)), the control signal for the speed mode is sent to the circuit switching valve 24. As a result, it is possible to operate at an increased speed until the load is hung, and then operate at a normal speed after the load is hung.

The "dead zone region" is a region in which the detected value of the load cell as a load meter is set in consideration of fluctuations in friction, vibration, inertia, etc., and there is substantially no suspended load. It is a range of detected values that can be judged as a state.
Further, for example, in the first embodiment described above, the speed-increasing circuit 20k has been described with an example of being configured by using a plurality of check valves, but the speed-increasing valve device according to the present invention is not limited to this. A spool may be used to form a speed-increasing circuit.

[Second Embodiment]
Hereinafter, a second embodiment of the speed-increasing valve device according to one aspect of the present invention, in which a spool is used in the speed-increasing circuit, will be described with reference to FIGS. 4 and 5 as appropriate.
As shown in FIG. 4, the speed-up valve device 1 of the second embodiment includes a load meter 2, a controller 3, and a speed-up valve 30. The speed-up valve device 1 of the second embodiment is different from the first embodiment in that the speed-up valve 30 is configured by using the spool 31.

As shown in FIG. 5, the speed-increasing valve 30 has a block-shaped valve body 38, and a circuit switching valve 34 is attached to the side surface of the valve body 38. Inside the valve body 38, a plurality of oil passages corresponding to the circuit shown in FIG. 4 are perforated, and a spool 31 having a switching groove for switching the communication state of the plurality of oil passages is formed along its own axial direction. It is built in so that it can be slid. Both ends of the spool 31 are plugged with plugs 32 and 33, and a coil spring 36 is interposed between one of the plugs 33 (left side in the figure) and the spool 31. The spool 31 is urged to the right in the figure by the coil spring 36.

Similar to the first embodiment, the speed-increasing valve device 1 of the second embodiment is a control signal from the controller 3 connected to the load meter 2 whether or not a current is passed through the solenoid inside the circuit switching valve 34. It is configured to be switched by.
That is, the controller 3 executes the speed-increasing operation control process similar to that of the first embodiment when the rod 13 is extended.

When the controller 3 of the second embodiment determines that the detected value of the load meter 2 is equal to or greater than the threshold value, the controller 3 shifts to the normal mode. At this time, the control signal is not output. As a result, no current flows through the solenoid of the circuit switching valve 34, and the pilot pressure of the circuit switching valve 34 does not occur. Therefore, as shown in FIG. 5A, the spool 31 of the valve body 38 is positioned to the right, which is urged by the coil spring 36.

Therefore, the pressure oil extruded from the contracted chamber 11 communicates with the second service port A1 through the oil passages A → B by the switching groove of the spool 31, and as shown in FIG. 4A, the second The pressure oil on the contraction chamber 11 side is discharged from the service port A1 to the tank port T. Therefore, in the normal mode, the pressure oil to the speed increasing circuit 30k is cut off and the rod 13 is extended at a normal speed.
On the other hand, when the controller 3 determines that the detected value of the load meter 2 is less than the threshold value, the controller 3 shifts to the speed mode and outputs a control signal to the circuit switching valve 34. When a current flows through the solenoid of the circuit switching valve 34 by the control signal, a pilot pressure of the circuit switching valve 34 is generated, and the pressure oil discharged from the pump 5 flows from the oil passage S in the circuit switching valve 34 to the oil passage Q. Enter the oil chamber R shown in 5 (b) and press the right end surface of the spool 31.

As a result, as shown in FIG. 5B, the spool 31 inside the valve body 38 slides to the left position against the urging force of the coil spring 36. Therefore, the oil passage is switched by the movement of the switching groove of the spool 31, and the pressure oil extruded from the second oil passage 8 on the contraction chamber 11 side causes the speed-increasing circuit 30k as shown in FIG. 4 (b). It joins the pressure oil discharged from the pump 5 through the oil passages C → D of the spool 31. Therefore, in the speed mode, the speed increasing circuit 30k is opened, and the pressure oil discharged from the contraction chamber 11 side of the cylinder 10 enters the extension chamber 12 side of the cylinder 10 to increase the extension speed of the rod 13.

Therefore, even with the speed-increasing valve device 1 of the second embodiment, the rod 13 can be extended at the speed-increased speed only when the detected value of the load meter 2 is less than the threshold value. As described above, even in the speed-increasing valve device 1 of the second embodiment in which the speed-increasing valve is configured by using the spool, the speed-increasing circuit can be appropriately switched according to the magnitude of the load carried by the double-acting hydraulic cylinder. ..

1 Speed-up valve device 2 Load meter 3 Controller 4 Switching valve 5 Pump 6 Tank 7 First oil passage 8 Second oil passage 10 Boom expansion / contraction cylinder (double-acting hydraulic cylinder)
11 Constriction 12 Expansion chamber 13 Rod 14 Tube 15 Piston 20 Speed-increasing valve 21 First check valve 22 Second check valve 23 Third check valve 24 Circuit switching valve 25 First pilot 26 Second pilot 27 Extension circuit 28 Valve body 29 Reduced circuit 30 Speed-up valve 31 Spool 32 Plug 33 Plug 34 Circuit switching valve 36 Spring 38 Valve body

Claims (3)

A speed-increasing valve device having a speed-up circuit that accelerates the extension speed of the rod by regenerating the pressure oil from the rod side of the double-acting hydraulic cylinder for expanding and contracting the boom of the crane to the head side.
A load cell attached to a boom operated by the expansion and contraction operation of the double-acting hydraulic cylinder and detecting a load carried by the boom, and a control signal corresponding to a comparison between a load value detected by the load cell and a preset threshold value. comprising a controller you output, and a speed increasing valve having a circuit switching valve for switching the speed increasing circuit based on a control signal from the controller which has the speed increasing circuit,
When the controller determines that the load value detected by the load cell is less than the threshold value , the controller sends a control signal for speed mode to the circuit switching valve, and determines that the load value detected by the load cell is equal to or more than the threshold value. When this happens, a control signal for the normal mode is sent to the circuit switching valve.
When the control signal is for speed mode, the speed-increasing valve opens the speed-up circuit and extends the rod at the accelerated speed, and when the control signal is for normal mode, the speed-increasing valve extends the rod. A speed-increasing valve device characterized in that the circuit switching valve interrupts the speed-increasing circuit and extends the rod at a normal speed. The threshold speed increasing valve device according to claim 1 Ru value der exceed the value of the load detected by the load cell in the suspended load is not state of the crane. The speed-increasing valve device according to claim 1 or 2 , wherein the speed-increasing valve is configured by using a spool.

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