JPS5932684B2 - hydraulic circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic circuit that uses a plurality of hydraulic pumps to enable stable joint operation of actuators such as cylinders and motors, as well as speed-up operation.

Conventionally, when connecting multiple actuators to a hydraulic pump, there are parallel connection methods and tandem connection methods.Parallel connection allows the actuators to be operated together, but pressure fluid flows to the actuator with the lighter load. Stable operation cannot be achieved because it tends to flow.

For example, if an actuator other than the motor is activated while the vehicle is traveling, the vehicle will meander.

In addition, if a tandem connection is used, if the upstream actuator is activated, the downstream actuator cannot be activated, and if the valve is operated to activate the downstream actuator, a vacuum state will occur due to the load, which will cause a shock during the next operation. This may cause other problems.

Further, although some conventional hydraulic pressure circuits have a speed increasing function, only a very limited number of circuits can speed up, and there is no one that can speed up a plurality of actuators.

The present invention was made to correct such a problem, and a pair of check valves are provided in the first supply pipe that communicates with the first pump and the tank, and the second supply pipe that communicates with the second pump. A third supply pipe connected downstream of both pumps by a connecting pipe and communicating with a third pump is communicated downstream of the connecting pipe connecting position of the second supply pipe via a check valve, and the second supply pipe The downstream end of the valve is branched, and each branch is provided with a second and third logic valve.
The upstream side of the second logic valve and the downstream side of the connection pipe connection position of the first supply pipe are connected via a check valve, and a position between the second logic valve and the pair of check valves of the connection pipe is connected. , the signal line of the second logic valve is releasably closed via a switching valve, the signal line of the third logic valve is releasably opened via a cutoff valve, and when the cutoff valve is actuated, The present invention is characterized in that the pressure liquid from the third pump is made to join the first supply pipe, and the pressure liquid from the third pump is made to join the connection pipe by operating a switching valve.

The present invention will be described in detail below with reference to the drawings.

1 and 2 show examples in which the present invention is implemented as a hydraulic circuit for a crawler type excavator, and first, the first embodiment will be explained with reference to FIG.

A shutoff valve 3 is connected to the first pump 1 through a pressure oil supply pipe 2, and a right-hand travel switching valve 4, a packet switching valve 5, and a first
A first logic valve 7 is provided downstream of the first boom switching valve 6 and connected in tandem with the boom switching valve 6, and the outlet of the logic valve 7 communicates with the tank 10.

Further, the left travel switching valve 13, the arm switching valve 14, and the second boom switching valve 15 are tandemly connected to the second pump 11 via a pressure oil supply pipe 12, and the pressure oil supply pipe 12 is connected to the second boom. A second logic valve 8.9 and a third logic valve 8.9 are provided downstream of the switching valve 15, respectively.

The outlet a of the second logic valve 8 is connected to the dual travel switching valves 4 and 1.
The upstream side of the second logic valve 8 is connected to the right travel switching valve 4 of the pressure oil supply pipe 2 and the packet valve. It communicates with the switching valve 5 via a check valve 19.

The outlet of the third logic valve 9 is in communication with the tank 10.

Next, the third pump 20 is connected to the turning switching valve 22 via the pressure oil supply pipe 21, and the pressure oil supply pipe 21 is connected to the left running switching valve 13 of the pressure oil supply pipe 12 via the check valve 23. and the arm switching valve 14.

Here, a motor, a cylinder, etc. are connected to each of the switching valves described above.

The valve position of each switching valve shown in the figure shows a neutral state, and when the valve position is switched to either the upper or lower position in the figure, the pressure oil supply pipe can be communicated with the motor and cylinder, and pressure oil can be supplied to these actuators. The direction of pressure oil supply can be changed by selecting the valve position.

The logic valves 7, 8, and 9 all have the same configuration, and in addition to the inlets to which the pressure oil pipes 2 and 12 are connected, the logic valve is provided with outlets a, b, and a signal port C. and the signal port C communicate with each other via a throttle valve.

When the signal port C is opened (the pilot pressure is released) in such a logic valve, the hydraulic pipe 5 and the outlet a.

When port b is in communication and signal port C is closed (pilot pressure increases), the hydraulic pipe and outlets a and b are cut off.

The signal port C of the first logic valve 7 is connected to the tank 10 via a signal line 24 via a cutoff valve 25 and a speed increase switching valve 26, and the signal port C of the second logic valve 8 is connected to the signal line 24. 27 is connected to the tank 10 via the speed increase switching valve 26.

Further, the signal port C of the third logic valve 9 is connected to the signal line 2.
8, the tank 1 is sequentially passed through the speed increase switching valve 26 and the cutoff valve 3.
0, and by operating the speed increase selector valve 26, the signal line 2
7 from closed to open, the signal line 24 is in communication with the signal line 28, and the signal line 28 is from open to closed.
Furthermore, by the operation of each cutoff valve 3, 25, 7, signal line 2
Configure the pilot circuit so that 8.24 goes from open to closed.

In addition, 29 is a preliminary switching valve connected to the upstream side of the first logic valve 7, and is interlocked with the above-mentioned cutoff valve 25.
, 31 and 32 are relief valves for circuit protection.

Hereinafter, the circuit operation in the merging operation and speed increasing operation of the actuators, which are the main features of the present invention, will be explained.

First, the merging operation will be explained.

In the state shown in FIG. 1, the signal port C of the 20th sick valve 8 is closed, and the signal ports C of the first and third logic valves 7 and 9 are open, so that the first pump 1 discharges The compressed oil is the first
Flows from the outlet of the logic valve 7 into the tank 10, and the second
Pressure oil discharged from the third pump 11゜20 is supplied to the supply pipe 12.
, 21 to the outlet of the third logic valve 9 to the tank 1
Flows to 0.

Now, when the left travel selector valve 13 is operated to drive the left travel motor, the pressure oil from the second pump 11 is cut off by the left travel selector valve 13, but the pressure oil from the third pump 20 is Since it is supplied to the second boom switching valve 14 and the second boom switching valve 15, the cylinder of the arm and boom can be driven.

Furthermore, when the right travel switching valve 4 is operated to drive the right travel motor, the cutoff valve 3 operates in conjunction with the switching valve 4 to close the signal port C of the third logic valve 9, and the logic valve 9 operates to close the outlets a and b.

The pressure oil of the second pump 11 and the third pump 20 is supplied to the supply pipe 12,
21, packet switching valve 5 of supply pipe 2 via check valve 19
It joins upstream of the river.

Therefore, although the pressure oil from the first pump 1 is cut off by the right travel switching valve 4, it is possible to drive each cylinder for the packet and boom with the pressure oil from the second pump 11 and the third pump 20. It is.

Furthermore, when the left and right travel switching valves 4 and 13 are operated, the pressure oil from the first and second pumps 1 and 11 is shut off by both valves 4 and 13, but the pressure oil from the third pump 20 is operated by the swing switching valve. 22, arm switching valve 14, second boom switching valve 15, second logic valve 8, packet switching valve 5, first boom switching valve 6
, so that any one of the switching valves along the path can be operated to drive the corresponding actuator.

When the travel motor and other actuators are jointly operated, pressurized oil is stably supplied to each motor and actuator independently from the pump, thereby preventing meandering or unstable operation of the actuators.

Furthermore, stable combined operation of various combinations of actuators is possible.

Next, the speed increasing operation will be explained.

When the speed increase switching valve 26 is operated with the left/right travel switching valves 4 and 13 operated, the signal port C of the second logic valve 8 opens, and the signal port C of the first and third logic valves 7°9 opens. is occluded.

Therefore, the supply pipe 12 and the connecting pipe 16 communicate with each other via the second logic valve 8, and the outlet port is blocked by the operation of the first logic valve 7, so that the supply pipe 2 and the tank 10 are cut off. .

For this reason, the pressure oil from the third pump 3 is divided by the connecting pipe 16 and joins the supply pipes 2 and 12, respectively, to increase the speed of the travel motor by the amount of the divided flow.

Furthermore, if the left running switching valve 13 is not operated, the corresponding actuator can be driven at increased speed by operating the arm switching valve 14 and the second boom switching valve 15.

Furthermore, when the left/right travel switching valves 4 and 13 and the speed increasing switching valve 26 are not operated, the pressure oil of the third pump 3 is transferred to the second pump 2.
The hydraulic oil is supplied to the arm switching valve 14 and the second boom switching valve 15 together with the pressure oil, and the cylinders of the arm and boom can be driven at increased speed.

As mentioned above, since the hydraulic circuit is constructed using logic valves, the flow state of the pressure oil can be easily changed according to the driving status of the actuator without the need for a complicated circuit configuration. It is possible to perform a combined operation of actuators and various types of combined operations, and also to perform a speed increasing operation without any problem.

Here, I will briefly touch on the operation of the spare switching valve 29. An additional actuator can be connected to the spare switching valve 29, and when the switching valve 29 is operated, the shutoff valve 25 is activated. Close the third signal port C.

The first logic valve 7 operates to shut off the supply pipe 2 and the tank 10, and the pressure oil in the supply pipe 2 is supplied to the actuator via the switching valve 29.

Furthermore, it goes without saying that the spare actuator can be driven even when the right travel switching valve 4 and the speed increase switching valve 26 are being operated at the same time.

Next, a second embodiment will be explained with reference to FIG.

Components in FIG. 2 that are the same as those in FIG. 1 are given the same numbers.

The logic valve described above can also be operated by a pilot circuit as described below.

The signal port C of the first logic valve 7 communicates with the tank 10 via the signal line 33 via the cutoff valve 25 and the speed increase switching valve 26', and the signal port C of the second logic valve 8 communicates with the tank 10 via the signal line 34. It is connected to the tank 10 via a switching valve 26'.

Further, the signal port C of the third logic valve 9 is connected to the signal line 35.
Then, the shutoff valve 37 linked to the first boom switching valve 6, the cutoff valve 36 linked to the packet switching valve 5, and the cutoff valve 3 linked to the right travel switching valve 4 are sequentially operated to connect to the tank 10. be.

Therefore, when the right travel switching valve 4 is operated, the signal port C of the third logic valve 9 is closed by the operation of the cutoff valve 3, and at the same time, the outlets a and b are also closed, and at least the third pump 20 is closed. The pressure oil from is supplied to the supply pipe 2.

Also, if the speed increase switching valve 26 is operated, the second logic valve 8
The signal port C of the first logic valve 7 is opened, the signal port C of the first logic valve 7 is closed, and the respective outlets a and b are opened and closed, so that the pressure oil from the third pump 20 is as same as in the first embodiment. Connecting pipe 16
The flow will be divided into

Note that, as in the first embodiment, the spare actuator can be driven by operating the spare switching valve 29.

In addition, the switching valve 5 for the packet and the switching valve 6 for the first boom are provided with cutoff valves 36 and 37, respectively, so that the line 35 can be cut off only when the switching valves 5 and 6 are operated. This is to enable the discharge pressure liquid from to be supplied and used.

As described above, according to the present invention, the operation of each actuator is stabilized during the merging operation, the speed increasing operation can be easily performed, and the circuit configuration is made of a logic valve, so it exhibits the excellent effect of being extremely simple. .

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram of an excavator showing a first embodiment of the present invention, and FIG. 2 is a hydraulic circuit diagram of the excavator showing a second embodiment. 2 is a pressure oil supply pipe, 3 is a cutoff valve, 7, 8.9 is a logic valve, 12 is a pressure oil supply pipe, 16 is a connection pipe, 21 is a pressure oil supply pipe, 26 is a speed increase switching valve, 24゜27 .28.33,34.
35 is a signal line, and 36 and 37 are cutoff valves.

Claims (1)

[Claims] 1 A first supply pipe that communicates the first pump and the tank, and a second supply pipe that connects the first pump and the tank.
A second supply pipe that communicates with the pumps is connected downstream of both pumps by a connecting pipe provided with a pair of check valves, and a third supply pipe that communicates with a third pump is connected to the connecting pipe connection position of the second supply pipe. communicates with the downstream end of the second supply pipe via a check valve, branches the downstream end of the second supply pipe, and provides second and third logic valves at each branch, and connects the upstream of the second logic valve with the first supply pipe. connected to the downstream side of the connection pipe connection position via a check valve, and connected to a position between the second logic valve and the pair of check valves of the connection pipe;
The signal line of the second logic valve is releasably closed via a switching valve, the signal line of the third logic valve is releasably opened via a cutoff valve, and the operation of the cutoff valve causes the third pump to be closed. A hydraulic circuit characterized in that the pressure liquid is made to join the first supply pipe, and the pressure liquid from the third pump is made to join the connection pipe by operating a switching valve.