JPH08189502A - Pilot operation hydraulic circuit for main change-over valve - Google Patents

Abstract

PURPOSE: To enable speed control without stop and abrupt operation in the change-over of actuator speed by connecting a throttle, relief valve and 2-port electromagnetic change-over valve in series to a circuit branched from between a main change-over valve and proportional pressure pilot valve. CONSTITUTION: When in the normal operational speed a 2-position electromagnetic change-over valve 17 is set to the closed position M and an operating lever 18 is gradually operated, a pilot valve 12 supplies oil pressure from a pilot oil pressure source 11 to either of both ends 2a, 2b of a main change-over valve 2 in proportion to the operation amount of the lever 18. Thus, flow rate in proportion to the operation amount is supplied to an actuator 3. When the flow rate to the actuator 3 is changed, the change-over 17 is set to the opened position P to send the pressure oil sent to either of both ends 2a, 2b of the main change-over valve 2 into a tank 4 through a throttle 14a or 14b, a relief valve 16 and the 2-position electromagnetic change-over valve 17. Thus, the flow rate to the actuator 3 can be sent from a starting point 0, so that operation stop and abrupt operation are avoided to improve operability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pilot operated hydraulic circuit for operating a main switching valve with pilot hydraulic pressure, and particularly to controlling the spool opening of the main switching valve for adjusting the speed of an actuator. Pilot operated hydraulic circuit.

[0002]

2. Description of the Related Art Conventionally, the switching of a main switching valve is operated by a pilot hydraulic pressure, the moving amount of a spool of the main switching valve is controlled by a pressure proportional to the pilot hydraulic pressure, and a flow rate according to the pilot hydraulic pressure is supplied to an actuator. The pilot operated hydraulic circuit of the main switching valve is used in construction machinery. Further, for example, in the lifting work of a crane vehicle, the speed of expansion and contraction and turning of the boom may be controlled in two stages of high speed control and fine speed control. In this case, as shown in FIG.
In the pilot operated hydraulic circuit shown in FIG. 2, an open position (P) communicating with a closed position (M) that shuts off the circuit is provided between the main switching valve 2 that controls the pressure oil from the main hydraulic pressure source 1 and the proportional pressure pilot valve 12. A two-port solenoid operated directional control valve 17 provided with is arranged and the two-port solenoid operated directional control valve 17 is operated to adjust the pilot hydraulic pressure.

As an example of this, when the operator operates the operation lever 18 with the 2-port solenoid operated directional control valve 17 in the closed position (M) during normal speed operation, as shown by the solid line in FIG. , When the pilot hydraulic pressure becomes Pia, the main switching valve 2 starts flowing from the flow point Q0 to the actuator 3 as shown by the solid line (a) in FIG. 9, and when the pilot hydraulic pressure becomes the maximum hydraulic pressure Pib, the main switching valve 2 The valve 2 allows a maximum flow rate Qm.

Next, when fine speed control is performed, the 2-port solenoid operated directional control valve 17 is set to the open position (P) to reduce the pilot hydraulic pressure. In this case, in this circuit, the pilot hydraulic pressure is controlled by the two throttles 13 and 14. At this time, for example, the two throttles 13 and 14 are set so that the pilot hydraulic pressure becomes half the conventional pressure [shown by the one-dot chain line (ro) in FIG. 9]. As a result, when the pilot hydraulic pressure reaches Pia (intersection point a), the main switching valve 2 starts flowing from the flow point Q0s to the actuator 3 as indicated by the alternate long and short dash line (b) in FIG. 9, and the pilot hydraulic pressure reaches the maximum hydraulic pressure Pib. Half the hydraulic pressure P
When the id is reached, the main switching valve 2 supplies the flow rate Qms.

[0005]

However, the pilot valve 12 is operated at the position of the normal speed shown in FIG. 8 to perform the normal crane work, that is, the 2-port solenoid operated directional control valve 17 is closed. The state in the position (M) is switched to the state in which the crane work is performing the fine speed control, that is, the state in which the two-port electromagnetic switching valve 17 is placed in the tank 4 in the open position (P). As a result, the pilot oil pressure is reduced to half, so that the spool (not shown) of the main switching valve 2 is returned and the supply of pressure oil to the actuator 3 is stopped. That is, in FIG. 9, since the supply start point of the flow rate to the actuator 3 shifts from the flow point Q0 to the flow point Q0s, if the pilot hydraulic pressure is in the range of the hydraulic pressure Pia to the hydraulic pressure 2Pia on the solid line (I), the main switching valve Since the spool (not shown) 2 moves to the neutral position, the crane work is stopped. That is, the main switching valve has a problem that a dead zone portion is generated.

On the contrary, when the 2-port solenoid operated directional control valve 17 is switched from the open position (P) communicating with the tank 4 to the position closed position (M) of FIG. If the hydraulic pressure is between 0.5 Pia and the hydraulic pressure Pia in (b), the working machine suddenly operates from a stop, giving the operator an unexpected movement and possibly causing a danger to surrounding workers. is there.

Further, as shown in FIG. 9, even if the pilot oil pressure is controlled in half, the flow rate flowing to the actuator is further reduced, and the work speed when the speed of the work machine is changed from that in normal work There is a problem that the operability is poor because it does not change at a constant ratio between cases. In particular, when operating a multistage cylinder such as a crane or actuators of different capacities with the same main switching valve, if the speed of each stage is adjusted using the embodiment shown in FIG. There is a problem of poor operability.

The present invention focuses on the above-mentioned conventional problems, and relates to a pilot operation hydraulic circuit for operating a main switching valve by pilot hydraulic pressure, and particularly when the speed of an actuator is switched, it is stopped or suddenly operated. It is an object of the present invention to provide a pilot operated hydraulic circuit which is capable of controlling the speed without the need of controlling the speed, and which has a predetermined ratio of changing speeds and has good operability.

[0009]

In order to achieve the above object, in the first aspect of the present invention, there is provided a main switching valve which receives a pilot hydraulic pressure from a proportional pressure pilot valve and controls a flow rate to an actuator. The pilot operated hydraulic circuit of the switching valve is characterized in that the throttle, the pressure regulating valve, and the two-port electromagnetic switching valve are connected in series to a circuit branched from between the main switching valve and the proportional pressure pilot valve.

A second aspect of the present invention is a pilot operation hydraulic circuit for a main switching valve, which has a main switching valve for receiving a pilot hydraulic pressure from a proportional pressure pilot valve to control a flow rate to an actuator, and is proportional to the main switching valve. A variable throttle valve and a pressure regulating valve are connected in series to a circuit branched from the pressure pilot valve.

A third aspect of the present invention is a pilot operation hydraulic circuit for a main switching valve, which has a main switching valve that receives a pilot hydraulic pressure from a proportional pressure pilot valve and controls a flow rate to an actuator. A selection switch for selecting either low pressure, a pressure switch or pressure sensor arranged between the main switching valve and the proportional pressure pilot valve, and a circuit branched from between the main switching valve and the proportional pressure pilot valve, It is characterized by comprising a high-speed switching valve and a pressure regulating valve connected in series, a selection switch, and a controller for outputting a high-speed switching command to the high-speed switching valve by a signal from the pressure switch or the pressure sensor.

A fourth aspect of the present invention is a main switching device having a main switching valve for controlling a flow rate to an actuator by receiving a pilot hydraulic pressure from a proportional pressure pilot valve which outputs a proportional pressure according to an operation amount of an operating lever. In the valve pilot operation hydraulic circuit, an operation amount sensor that detects the operation amount of the operation lever, a selection switch that selects high or low pilot oil pressure, and a branch between the main switching valve and the proportional pressure pilot valve And a controller for outputting a high-speed switching command to the high-speed switching valve by a signal from a selection switch and an operation amount.

According to a fifth aspect of the present invention, in a pilot operation hydraulic circuit of a main switching valve having a main switching valve for controlling a flow rate to an actuator by receiving pilot hydraulic pressure from a proportional pressure pilot valve, the pilot hydraulic pressure is set to a high pressure or a high pressure. A selection switch for selecting either low pressure, a pressure sensor arranged between the main switching valve and the proportional pressure pilot valve,
A high-speed switching valve provided in a circuit branched from the main switching valve and the proportional pressure pilot valve, and a controller that outputs a high-speed switching command to the high-speed switching valve by a signal from a selection switch and a pressure switch. To do.

[0014]

With the above structure, the starting point for supplying the flow rate from the main switching valve to the actuator is the same regardless of whether the pilot hydraulic pressure for operating the main switching valve is high or low. Also, the operation of the working machine is not stopped or suddenly operated, and the supply amount of the flow rate to the actuator can be set to a predetermined ratio.

Also, the flow rate gradient from the main switching valve to the actuator can be adjusted by changing the pilot oil pressure by adjusting the throttle and the variable throttle valve.
Further, since the hydraulic pressure of the pilot valve and the adjusted flow rate of the high-speed switching valve can be automatically controlled by the controller, the flow rate from the main switching valve to the actuator can be arbitrarily adjusted.
Also, the speeds of actuators (cylinders) having different capacities can be operated at a constant speed with respect to the operation amount of the operation lever by appropriately selecting the hydraulic pressure of the pilot valve.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pilot operated hydraulic circuit for a main switching valve according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a pilot operation hydraulic circuit diagram of a first embodiment in which a main switching valve is operated by pilot oil pressure. FIG. 2 is a view for explaining the relationship between the displacement of the operating lever and the pilot hydraulic pressure and the flow rate to the actuator in the first embodiment. In FIG. 1, the pressure oil from the main hydraulic power source 1 is
It is supplied to the actuator 3 via the main switching valve 2 that controls the flow rate according to the movement amount of the spool (not shown), and
Return oil from the actuator 3 is returned to the tank 4 via the main switching valve 2. Both ends 2a, 2b of the main switching valve 2
Are connected to the pilot operated hydraulic circuit 10.

The pilot operating hydraulic circuit 10 includes a pilot hydraulic pressure source 11, a proportional pressure pilot valve 12 (hereinafter, referred to as pilot valve 12), two throttles 13 and 14, and
It comprises a shuttle valve 15, a pressure regulating valve 16, and a two-position electromagnetic switching valve 17. In the above structure, the oil from the pilot hydraulic power source 11 is supplied to the pair of pilot valves 12
The values a and 12b enter and are output as pilot hydraulic pressure. At this time, an operation lever 18 is attached to the pilot valve 12, and the pilot oil pressure is changed to the operation lever 18
Pilot pressure P of proportional pressure according to the displacement of the operation amount S of
Output i. This pilot oil pressure Pi is one throttle 1
It is supplied to both end portions 2a, 2b of the main switching valve 2 via 3.
Further, the pilot operated hydraulic circuit 10 includes one throttle 13
And a branch between both ends 2a and 2b of the main switching valve 2,
Each of the branched circuits 19a and 19b (branch circuit 19
a) and 19b), the other diaphragms 14a and 14b are respectively arranged. Further, the other diaphragms 14a, 14
After b, the shuttle valve 15 merges and the shuttle valve 15
A pressure regulating valve 16 and a two-position electromagnetic switching valve 17 are connected in series with. Further, the two-position electromagnetic switching valve 17 is connected to the tank 4.

In the above embodiment, the shuttle valve 15 is merged, and the shuttle valve 15 is connected in series with the pressure regulating valve 16 and the two-position electromagnetic switching valve 17, but the shuttle valve 15 is not provided and the pressure regulating valve is not provided. 16 and 2-position solenoid switching valve 1
Two throttles 7 are used, and the throttle 14a and the pressure regulating valve 1 are separately provided.
6, 2 position electromagnetic switching valve 17 and the circuit of tank 4, and throttle 14b, pressure regulating valve 16, 2 position electromagnetic switching valve 17
Alternatively, the circuit of the tank 4 may be used.

The operating condition will be described with reference to FIGS. For example, when working at a normal working speed, the 2-port electromagnetic switching valve 17 is kept in the closed position (M). In this case, the operation is similar to that of the conventional example shown in FIG. That is, when the operation lever 18 is gradually operated, the pilot valve 12 causes the pilot oil pressure from the pilot oil pressure source 11 proportional to the operation amount of the operation lever 18 to be applied to either end 2 of the main switching valve 2.
a, 2b. Therefore, the spool (not shown) moves, the spool opening changes, and the flow rate proportional to the operation amount is supplied to the actuator 3, and the actuator 3 operates at a predetermined speed proportional to the operation amount. This state will be described with reference to FIG. Due to the displacement of the operation amount S of the operation lever 18, the pilot oil pressure Pi from the pilot oil pressure source 11 is indicated by a solid line.
, The spool opening degree (not shown) of the main switching valve 2 is controlled accordingly, and the flow rate Q to the actuator 3 changes as shown by the solid line (a). That is, when the pilot hydraulic pressure reaches Pia, the main switching valve 2 starts flowing from the flow point Q0 as shown by the solid line (a), and when the pilot hydraulic pressure reaches the maximum hydraulic pressure Pib, the main switching valve 2 reaches the maximum flow rate. Flow Qm.

Next, when the flow rate to the actuator is changed, a two-port electromagnetic switching valve 17 is set to the open position (P) by operating a selection switch (not shown), and the pilot hydraulic power source 11 to the main switching valve 2 is operated. The pressure oil supplied to either end 2a or 2b of the
b, flow from the shuttle valve 15 to the tank 4 via the pressure regulating valve 16 and the two-position electromagnetic switching valve 17. For example, in the case of fine speed control, as in the conventional example [shown by the alternate long and short dash line (ro) in FIG. 8], as shown by the alternate long and short dash line (ro) in FIG. An example will be described. In this case, the valve opening pressure of the pressure regulating valve 16 starts to flow from the main switching valve 2 to the actuator 3 as in the case where the 2-port electromagnetic switching valve 17 is in the closed position (M).
It should be set equal to ia. As a result, the flow rate starting point to the actuator 3 flows from the flow rate point Q0.
At this time, the pilot hydraulic pressure Pid at the maximum stroke of the operating lever (0.5 Pib in this embodiment)
Is adjusted to half the maximum oil pressure Pib by the throttle 14a or 14b and the pressure regulating valve 16. This allows
As shown by the alternate long and short dash line (b) in FIG. 2, the pilot hydraulic pressure Pid has the maximum flow rate Qms when the pilot hydraulic pressure reaches the maximum hydraulic pressure Pid. From the above,
The starting point of the flow rate to the actuator 3 is the same, and the flow can start from the flow rate point Q0. Further, by appropriately selecting the throttle amount of the throttles 14a or 14b, the pilot oil pressure Pi for changing the flow rate gradient to the actuator is obtained.
Can be appropriately selected. Accordingly, the flow rate to the actuator can be appropriately selected before and after the change, and thus the flow rate ratio can also be appropriately selected.

FIG. 3 is a pilot operating hydraulic circuit diagram of the second embodiment in which the main switching valve is operated by pilot hydraulic pressure. First
The difference from the embodiment of FIG. 1 is that a two-position variable throttle valve 21 (hereinafter referred to as a variable throttle valve 21) that can be manually adjusted is provided in place of the throttle valve 14 and the two-port solenoid valve, and a two-port solenoid switch valve is provided. The configuration also has 17 functions.

The operating condition will be described with reference to FIG. When the variable throttle valve 21 is in the closed position (R), it is the same as in the first embodiment, and the description thereof is omitted. Next, when changing the flow rate to the actuator, the variable throttle valve 8 is manually operated to the open position (T), and either of the both ends 2a, 2b of the main switching valve 2 from the pilot hydraulic power source 13 is operated. The pressure oil supplied to the crab is flowed from the variable throttle valve 8 to the tank 4 via the pressure regulating valve 16. At this time, the starting point of the flow rate supply to the actuator 3 is the pilot oil pressure P at which the opening pressure of the pressure regulating valve 16 starts to flow from the main switching valve 2 to the actuator 3 as in the first embodiment.
It should be set equal to ia. Further, the pilot oil pressure Pi corresponds to the operation amount S of the operation lever 18 as indicated by 2 in FIG.
As indicated by the dotted chain line (), it is possible to set an arbitrary gradient by appropriately adjusting the throttle of the variable throttle valve 21,
The flow rate Q to the actuator 3 can be arbitrarily controlled within the range of the chain double-dashed line (c) shown in FIG. 4, and the flow rate point Q0 does not change.

FIG. 5 is a pilot operating hydraulic circuit diagram of the third embodiment in which the main switching valve is operated by pilot hydraulic pressure. First
The difference from the embodiment shown in FIG. 1 is that the throttle valve 14 is eliminated and a pressure switch 31, a 2-position high-speed switching valve 32, a controller 33, and a selection switch 34 are added. The pressure switch 31 is arranged between the pilot valve 3 and the throttle 13 and detects the operating direction of the operating lever 18. The high-speed switching valve 32 is arranged between the shuttle valve 15 and the pressure regulating valve 16 to open and close at high speed, and sends the pilot oil pressure Pi to the pressure regulating valve 16 based on a command. Further, the controller 33 is configured to receive a pressure signal from the pressure switch 31 and the selection switch 34 and output a predetermined command to the high speed switching valve 32.

Next, the operating condition will be described. The operation lever 18 is operated in either direction according to a desired operation. This operation direction is detected by the pressure switches 31a and 31b, and the detected pressure signal is transmitted to the controller 33. The controller 33 outputs a command to the high speed switching valve 32 according to the operation direction. At this time, for example, when the selection switch 34 has a normal work speed of 0FF, the duty ratio Δ [the ratio of the open (U) / close (V) of the high-speed switching valve 32 shown in FIG. ] Is zero, that is, the high-speed switching valve 32 outputs a command to close. As a result, the amount of pilot drain becomes zero, and the pressure regulating valve 16
Pilot oil pressure Pi does not act on the. Therefore, the pilot oil pressure Pi of the pilot valve 3 remains unchanged as it is in the main switching valve 2.
When the pilot hydraulic pressure reaches the maximum hydraulic pressure Pib, the main switching valve 2 starts to flow from the flow point Q0 to the main switching valve 2 as shown by the solid line (a) in FIG. 2 flows the maximum flow rate Qm.

Next, when the selection switch 34 performs the fine speed control of 0N, the high-speed switching valve 32 is set to the high speed switching valve 32 as shown in FIG.
The duty ratio Δ is set to a desired δ. As a result, the pilot drain amount becomes qia, and the pilot drain amount qia flows through the pressure regulating valve 16. At this time, the pressure is set so that the pressure regulating valve 16 is opened when the pilot hydraulic pressure of the pilot drain amount qia becomes the hydraulic pressure Pia. As a result, similarly to the first embodiment, the flow rate Q to the actuator 3 can be arbitrarily controlled within the range of the dotted line (b) shown in FIG. 2, and the flow rate point Q0 does not change. Further, in the above, by changing the duty ratio δ of the high-speed switching valve 32 by an external signal, the inclination of the pilot oil pressure Pi for changing the flow rate to the actuator can be appropriately selected. In the above, the pressure switch 31 may be a pressure sensor.

FIG. 5 also shows a pilot operating hydraulic circuit diagram of the fourth embodiment in which the main switching valve is operated by pilot hydraulic pressure. 5 is different from the third embodiment in that the pressure switch 31 and the pressure regulating valve 16 are eliminated and the pressure sensor 41 and the operation amount sensor 42 are added. The pressure sensor 41 is arranged between the pilot valve 3 and the throttle 13 to detect the pressure of pilot oil pressure. The operation amount sensor 42 is the operation lever 18
Is arranged in the vicinity of to detect the operation amount of the operation lever 18. Further, the controller 33 receives the pressure signals from the pressure sensor 41, the operation amount sensor 42, and the selection switch 34 and outputs a predetermined command to the high-speed switching valve 32.

Next, the operating condition will be described. The operation lever 18 is operated in either direction according to a desired operation. This operation direction is detected by the pressure sensors 41a and 41b, and the detected pressure signal is transmitted to the controller 33. The controller 33 outputs a command to the high speed switching valve 32 according to the operation direction. At this time, for example, when the selection switch 34 has a normal working speed of 0FF, the controller 33 causes the high-speed switching valve 32 to have a duty ratio δ of zero, that is, the high-speed switching valve by the signal that the selection switch 34 is 0FF. 32 outputs a command to close. Since this is the same as the third embodiment, the description is omitted.

Next, when the selection switch 34 performs the fine speed control of 0N, the high speed switching valve 32 is set to the high speed switching valve 32 as shown in FIG.
A variable duty ratio δx is output according to the pilot oil pressure Pi. At this time, for example, at a normal working speed, the pilot hydraulic pressure that starts to flow from the main switching valve 2 to the actuator 3 is the hydraulic pressure Pia, and the flow rate starting point to the actuator 3 flows from the flow rate point Q0. At this time, the operation amount Sa of the pilot oil pressure Pia is detected by the operation amount sensor 42. When performing fine speed control,
The controller 33 detects the operation direction by the pressure signals from the pressure sensors 41a and 41b, and detects that the fine speed control is selected by the signal from the selection switch 34.
When this signal is received and the operation amount Sa of the operation lever 18 at a predetermined stroke position is detected by the signal from the operation amount sensor 42, the main switching valve 2 causes the actuator 3 to operate.
The pilot hydraulic pressure Pi is controlled to the hydraulic pressure Pia so as to start flowing the flow rate to the. This is because the controller 33 causes the pilot oil pressure Pi to be applied to the high-speed switching valve 32 as shown in FIG.
To a predetermined oil pressure Pia, a predetermined duty ratio δ
Output x. Further, when the operation lever 18 is operated to increase the operation amount S, the duty ratio δx is decreased in accordance with the operation amount S as shown by the dashed line (e) in FIG.
The pilot drainage amount is reduced to increase the pilot hydraulic pressure Pi. As described above, the controller 33 stores the duty ratio Δx of the high-speed switching valve 32 corresponding to the operation amount S by operating the operation lever 18, and outputs the duty ratio Δx to the high-speed switching valve 32 to obtain a desired pilot hydraulic pressure. it can.

In the above embodiment, the operation amount sensor 42
The duty ratio δx of the high speed switching valve 32 is switched according to the above, but the duty ratio δx of the high speed switching valve 32 when the pilot oil pressure Pi is detected by the pressure sensor 41 and the fine speed control corresponding to this pilot oil pressure Pi is performed. The controller may store and output it to the high-speed switching valve 32 to obtain a desired pilot hydraulic pressure. Further, in the above description, the normal working speed and the speed when the fine speed control is performed have been described, but the slow speed control may be the normal working speed, and the normal working speed may be the high working speed.

[0030]

As described above, according to the present invention, the starting point for supplying the flow rate from the main switching valve to the actuator is the same regardless of whether the pilot hydraulic pressure for operating the main switching valve is switched to high or low. Even if the pilot hydraulic pressure is switched, the work machine does not stop operating or suddenly operate, and the amount of flow rate supplied to the actuator can be set to a predetermined ratio, so there is no discomfort in lever operation and operability is improved. To do.

Since the flow rate can be controlled without providing the flow rate control valve in the main hydraulic circuit, the structure is simple. Also, since variable throttle valve or high-speed switching valve is connected to pilot hydraulic pressure to enable stepless flow rate control, various work that requires speed control over a wide range of work machines such as crane work can be easily performed. .

As seen in the telescopic boom of a mobile crane, when actuators (cylinders) of different capacities are expanded and contracted in several stages in series, speed changes (rapid acceleration, deceleration) occur when switching to the next stage, but each actuator operates. By guiding the signal for detecting the position to the controller and controlling it using the variable throttle valve or the high-speed switching valve, the boom can be expanded and contracted at a constant speed without changing the speed.

[Brief description of drawings]

FIG. 1 shows a pilot operation hydraulic circuit diagram of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating performance characteristics of the first embodiment of the present invention.

FIG. 3 shows a pilot operation hydraulic circuit diagram of a second embodiment of the present invention.

FIG. 4 is a diagram illustrating the performance characteristics of the second embodiment of the present invention.

FIG. 5 shows pilot operation hydraulic circuit diagrams of a third embodiment and a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a duty ratio (opening / closing ratio) and a drain flow rate of a high speed switching valve according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a duty ratio (opening / closing ratio) and an operation amount of a high speed switching valve according to a fourth embodiment of the present invention.

FIG. 8 shows a pilot operation hydraulic circuit diagram of a conventional embodiment.

FIG. 9 shows performance characteristics of a conventional example.

[Explanation of symbols]

1 main hydraulic power source, 2 main switching valve, 3 actuator, 4 tank, 11 pilot hydraulic power source, 12
Proportional pressure pilot valve, 13/14 throttle, 15 shuttle valve, 16 pressure regulating valve, 17 2-position solenoid switching valve,
18 operation lever, 19 branch circuit, 21 2 position variable throttle valve, 31 pressure switch, 32 high speed switching valve, 33 controller, 34 selection switch, 4
1 pressure sensor, 42 operation amount sensor.

Claims (5)

[Claims] 1. A pilot operation hydraulic circuit of a main switching valve having a main switching valve for controlling a flow rate to an actuator by receiving pilot hydraulic pressure from the proportional pressure pilot valve, and between the main switching valve and the proportional pressure pilot valve. A pilot operated hydraulic circuit for a main switching valve, in which a throttle, a pressure regulating valve and a two-port electromagnetic switching valve are connected in series to a branched circuit. 2. A pilot operation hydraulic circuit of a main switching valve having a main switching valve that receives a pilot hydraulic pressure from the proportional pressure pilot valve to control a flow rate to an actuator, from between the main switching valve and the proportional pressure pilot valve. A pilot operated hydraulic circuit for a main switching valve, in which a variable throttle valve and a pressure regulating valve are connected in series to a branched circuit. 3. A pilot operation hydraulic circuit of a main switching valve, which has a main switching valve for receiving a pilot hydraulic pressure from a proportional pressure pilot valve and controlling a flow rate to an actuator, selects either high pressure or low pressure as the pilot hydraulic pressure. A high-speed switching valve connected in series in a circuit branched from the selection switch, the pressure switch or pressure sensor arranged between the main switching valve and the proportional pressure pilot valve, and between the main switching valve and the proportional pressure pilot valve. And a pressure regulator,
A pilot operation hydraulic circuit for a main switching valve, comprising: a selection switch; and a controller that outputs a high-speed switching command to the high-speed switching valve in response to a signal from a pressure switch or a pressure sensor. 4. A pilot operation hydraulic circuit for a main switching valve having a main switching valve that receives a pilot hydraulic pressure from a proportional pressure pilot valve that outputs a proportional pressure according to an operation amount of an operating lever and controls a flow rate to an actuator. The operation amount sensor that detects the operation amount of the operation lever, the selection switch that selects either high pressure or low pressure for the pilot hydraulic pressure, and the high-speed switching provided in the circuit branched from the main switching valve and the proportional pressure pilot valve A pilot operated hydraulic circuit for a main switching valve, comprising a valve and a controller that outputs a high-speed switching command to the high-speed switching valve by a signal from a selection switch and an operation amount sensor. 5. A pilot operation hydraulic circuit of a main switching valve having a main switching valve that receives a pilot hydraulic pressure from a proportional pressure pilot valve to control a flow rate to an actuator, and selects either high pressure or low pressure as the pilot hydraulic pressure. A selection switch, a pressure sensor arranged between the main switching valve and the proportional pressure pilot valve, a high-speed switching valve provided in a circuit branched from between the main switching valve and the proportional pressure pilot valve, a selection switch and pressure. A pilot operated hydraulic circuit for a main switching valve, comprising a controller that outputs a high-speed switching command to the high-speed switching valve by a signal from a switch.