JPS5932682B2 - pressure fluid circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a pressure fluid circuit used in construction machines such as hydraulic excavators.

A construction machine, for example, a hydraulic excavator, includes various parts such as a traveling device, a swing device, a boom, a packet, and an earth removal plate, and each of these parts operates by supplying and discharging pressure fluid from a pressure fluid source. It is.

Each of the above parts has different operating conditions, such as when one device is operating, the other does not operate due to large differences in the operating pressure of the operating parts, etc. In addition, it is equipped with a pressure fluid circuit that matches the operating conditions of the part.
To ensure efficient use of power, a two-pump pressure fluid source is used in which two pumps are operated in parallel.

In such a hydraulic excavator, the traveling device and the earth removal plate must be operated at the same time to perform earth removal work while traveling, but one side of the traveling device supplies pressurized fluid to the actuator of the earth removal plate. When connected to a pressure fluid circuit, the flow rate of the pressure fluid supplied to the traveling device decreases, causing the traveling direction to curve.

To prevent this, a three-pump type pressurized fluid source with a dedicated pump for the earth removal plate can be used, but the earth removal plate has a small operating range, so the pressure fluid source should be a three-pump type. It's not worth it, and of course you'll be at a disadvantage in terms of price.

In order to solve these drawbacks of the three-pump type pressure fluid source, the pressure fluid source is made into a two-pump type, and a throttle and an opposite A valve device consisting of a stop valve and a directional switching valve for operating the soil discharge plate are provided, and multiple directional switching for supplying and discharging pressurized fluid to multiple actuators such as traveling devices is provided in parallel on the discharge side of the two pumps. A technique of connecting to a tank via a valve was disclosed as Japanese Utility Model Application No. 55-50166.

According to this technology, the soil removal plate can be operated only when one of the directional control valves of the other actuators is operated. It has the disadvantage that it cannot be operated by operating only the switching valve.

The present invention provides a pressure fluid circuit that operates a plurality of actuators, in which each of the plurality of actuators can be operated individually or simultaneously.

Hereinafter, FIG. 1 showing an embodiment according to the present invention will be described.

The pressure fluid circuit shown in FIG. 1 is connected to an engine (not shown).

), and the first discharge circuit 3 is operated in parallel on the discharge side.
a, the first pump 1a connected to the second discharge circuit 3b, the second pump
A pressure fluid source 2 consisting of a pump 1b and a first discharge circuit 3a
and directional control valves 30a, 31a, 32a and relief valves 6 to which the actuators of each part of the hydraulic excavator are connected.
A directional switching valve 30bj31b to which the first circuit 7, the second discharge circuit 3b, and the actuators of each part of the hydraulic excavator are connected. 32b and a relief valve 9, an actuator 11 for driving the earth discharge plate H, a first discharge circuit 3a, and a second discharge circuit 3b.
A third supply circuit 4 is connected to the third supply circuit 4 via a flow collecting valve device 12, and a discharge circuit 15 is connected to the tank T.

Directional switching valve 30a>31a of first circuit 7.

32a are actuators (not shown) of the first boom, packet, and traveling device, respectively.

) for supplying and discharging pressure fluid to and from the first load circuits 16a, 17a,
: 18a, 19a; 20a, 21a;, the first discharge circuit 3a, and the first supply circuit 2 branched from the first discharge circuit 3a.
2a, and a first discharge circuit 23a connected to the discharge circuit 15.
are connected and have a neutral position B and switching positions C and D.

This directional switching valve 30a. 30b and 30C are neutral position B
, the first discharge circuit 3a is connected to the tank T, forming a first unload circuit 24a that is closed when the switching position C or D is operated.

At this time, one load circuit of the operated directional control valve is
The load circuit is connected to a first supply circuit 22a branched from the first discharge circuit 3a, and the other load circuit is connected to a first discharge circuit 23a connected to the discharge circuit 15.

Directional switching valves 30b, 31b of the second circuit 10.

32b are actuators (not shown) of the swing device, the second boom, and the traveling device, respectively.

) for supplying and discharging pressure fluid to and from the second load circuits 16b and 17.
b, 18b.

19b? 20b, 21b; and a second supply circuit 22b and a discharge circuit 1 branched from the second discharge circuit 3b.
5 is connected to the second discharge circuit 23b, and
It has a neutral position B and switching positions C and D.

These directional switching valves 30b, 31b, 32b connect the second discharge circuit 3b to the tank T when in the neutral position B, and form a second unload passage 24b that is closed when operated to the switching position C or D. do.

At this time, one load circuit of the operated directional switching valve is connected to the second supply circuit 22b branched from the second discharge circuit 3b, and the other load circuit is connected to the second discharge circuit 23b connected to the discharge circuit 15. do.

The directional switching valve 5 of the third circuit 14 is connected to an actuator 11 (hereinafter referred to as cylinder 11) that operates the earth removal plate H.

) pressure chamber 11a on the bottom side, pressure chamber 11b on the rod side
The third load circuits 25 and 26 connected to each of the three, the third supply circuit 4 connected to the flow collector device 12, and the third discharge circuit 27 connected to the discharge circuit 15 are connected, and the neutral position B, It has switching positions C and D.

When the directional control valve 5 is in the neutral position B, the first unload circuit 24a and the second unload circuit 24b connected to the tank T via the discharge circuit 15 are connected to a third unload circuit. 28 and switch position C.
Or when operated in D, one of the third load circuits 25 and 26 is connected to the third supply circuit 4 and the other is connected to the third discharge circuit 27.
Connect to.

First and second discharge circuits 3a, 3b and third supply circuit 4
The flow collector device 12 provided between the flow collector circuit 12 includes a first flow collector circuit 37a in which a check valve 35a and a throttle 36a are connected in series, and a second flow collector circuit 37a in which a check valve 35b and a throttle 36b are connected in series. Road 37
b, and the first and second discharge circuits 3a, 3b
are the check valves 35a of the first and second collector circuits 37a and 37b, respectively.

35b, the third supply circuit 4 is connected to the upstream side of the aperture 36
Connect to the downstream side of at36b.

Note that the upstream sides of the check valves 35 a and 35 b are the first,
It may also be connected to the second supply circuits 22a and 22b.

The operation of this embodiment having the above configuration will be described.

Directional switching valves 30 for the first, second, and third circuits 7, 10, and 14
a , 31 a , 32 a , 30 b , 31 b .

32b and the directional control valve 5 in the neutral position B, when the pressure fluid source 2 is driven, the first pump 1a of the pressure fluid source 2
The discharge fluid flows out into the tank T via the first discharge circuit 3a, the first and third unload circuits 24a and 2B, and the discharge circuit 15.

Further, the discharge pressure fluid of the second pump 1b is supplied to the second discharge circuit 3.
b, flows out to the tank T via the second unload circuit 24b and the discharge circuit 15.

In order to operate only the soil discharge plate H, when the directional switching valve 5 is operated to the switching position, the third unload circuit 28 is closed, thereby cutting off the connection between the first unload circuit 24a and the discharge circuit 15. , each of the third load circuits 25 and 26
It is connected to the supply circuit 4 and the third discharge circuit 27.

At this time, the second unload circuit 24b is connected to the discharge circuit 15.
It is connected to the tank via.

Therefore, the discharge pressure fluid of the first pump 1a of the pressure fluid source 2 is distributed to the first discharge circuit 3a, the first flow collector circuit 37a of the flow collector device 12, the third supply circuit 4, the directional control valve 5, the third It flows into the pressure chamber 11a on the bottom side of the cylinder 11 via one of the load circuits 25.

The fluid in the pressure chamber 1ib on the Rondo side of the cylinder 11 is transferred to the other load circuit 26 of the third load circuit, the directional control valve 5
, the tank T via the third discharge circuit 27 and the discharge circuit 15.
leaks to.

Therefore, the earth removal plate H operates downward, and the operating speed at this time is a value corresponding to the amount of restriction of the restriction 36a of the flow collecting valve device 12.

Next, a case will be described in which the earth removal plate H is operated while the traveling device is in operation.

When the directional switching valve 32a of the first circuit 7 and the directional switching valve 32b of the second circuit 10 are simultaneously operated to the switching position, the first
, the unload circuit 24a is closed, and the load circuits 21a and 20a are connected to the first supply circuit 22a and the first discharge circuit 23a, respectively.

Similarly, the second unload circuit 24b is closed, and
The load circuits 21 b, t 20 b are respectively the second supply circuit 2
2b and the second discharge circuit 23b.

Therefore, the first and second pumps 1a of the pressure fluid source 2,
The discharge pressure fluid of 1b is the directional switching valve 32a>3
2b to the actuator of the traveling device, and the discharge side of the actuator of the traveling device is a directional switching valve 32a.

32b to the first and second discharge circuits 23a.

23b, flows out into the tank T via the discharge circuit 15.

Therefore, the actuator of the traveling device operates, but at this time, the operating speed is the same as that of the directional control valve 32a.

The value corresponds to the operation amount of 32b.

When the directional control valve 5 of the third circuit 14 is operated to the switching position while the actuator of the traveling device is in operation, the load circuits 25 and 26 of the cylinders 11 of the earth removal plate H are connected to the third supply circuit 4 and the third circuit 14. Connect to the discharge circuit 27.

At this time, a part of the discharge pressure fluid of the first and second pumps 1a and 1b is transferred to the first and second flow collecting circuits 37a of the flow collecting valve device 12.
, 37b, the third supply circuit 4, and the directional control valve 5, and then flows into the pressure chamber 11a on the bottom side of the cylinder 11.

The fluid in the pressure chamber 11b on the Rondo side flows out to the tank T via the directional control valve 5, the third discharge circuit 2T, and the discharge circuit 15.

Therefore, the earth removal plate H can operate simultaneously with the traveling device.

At this time, the operating speed of the earth removal plate H becomes a value corresponding to the sum of the throttle amounts of the throttles 36 a > 36 b of the flow collecting valve device 12 .

In this way, the operating speed of the earth removal plate H is slightly different depending on whether the earth removal plate H is operated alone or when the earth removal plate H and other equipment are operated simultaneously. Since the operating conditions required for H are often only simple upward and downward movement, this difference in operating speed is not a problem.

If this point becomes a problem, the flow collecting valve devices shown in FIGS. 1, 2, and 3 may be used.

FIGS. 2 and 3 are diagrams showing other embodiments of the flow collecting valve device 12. FIG.

The collector valve device 12a shown in FIG. 2 includes a first discharge circuit 3a of the first pump 1a and a second discharge circuit 3 of the second pump 1b.
Its input side 41 a t 4 l b is connected to its output side 42a.

42b is an in-line flow control valve 40a having a backflow prevention function connected to the third supply circuit 4;

The in-line flow control valves 40a and 40b are formed by combining the first and second in-line flow control valves 40a and 40b, respectively.
By making the fluid pressures in the discharge circuits 3a, 3b and the third supply circuit 4 act against each other, the first and second discharge circuits 3a
>3 Maintain the pressure fluid supplied from b to the third supply circuit 4 at a constant value regardless of the fluid pressure in the first and second discharge circuits and the third supply circuit 4. A flow collector valve device shown in FIG. 12b is the first discharge side circuit 3a of the first pump 1a and the second discharge circuit 3 of the second pump 1b.
It is composed of a flow collecting valve 44 having an input side 46a>46b connected to each of b via check valves 45a and 45b, and an output side 47 connected to the third supply circuit 4.

This flow collecting valve 44 has an input side 46at46b and an output side 47.
The first and second discharge circuits 3
This is to keep the amount of pressure fluid supplied from a and 3b to the third supply circuit 4 constant.

As described above, according to the present invention, a pressure fluid source having a plurality of pumps is provided with a third circuit that connects the unload circuit of the eleventh and second circuits that are connected to the discharge pressure fluid of each pump, and Since the third circuit has a configuration in which a flow collecting valve device is interposed between the pressure fluid source and the third circuit, simultaneous operation of the third circuit, first and second circuits, and independent operation of only the third circuit It has the effect of allowing you to freely perform the following.

[Brief explanation of the drawing]

FIG. 1 is a pressure fluid circuit diagram of an embodiment according to the present invention;
2 and 3 are circuit diagrams showing other embodiments of the flow collecting valve device. 1a...First pump (2 pressure fluid sources), 1b.
...Second pump (two pressure fluid sources), 3a...
...First discharge circuit, 3b...Second discharge circuit, 4
......Third supply circuit, 5...Directional switching valve, 7...First circuit, 10...Second circuit, 11...・Actuator, 12...
Flow collector device, 14...Third circuit, 16a. 17a, 18a, 19a, 20a, 21a...
Load circuits, 16b, 17b, 18b, 19b. 20b, 21b...Load circuit, 22a...
...first supply circuit, 22b...second supply circuit,
23a...First discharge circuit, 23b...
Second discharge circuit, 24a...First unload circuit, 24b...Second unload circuit, 25, 26
...Load circuit, 27...Third discharge circuit, 28...Third unload circuit, 30a. 31a, 32a-first directional valve, 30b. 31b, 32b...Second directional control valve.

Claims (1)

[Claims] 1 A pressure fluid source including a first pump having a first discharge circuit and a second pump having a second discharge circuit, and a first supply circuit branched from the first discharge circuit of this pressure fluid source,
a first forming a first unload circuit connected to the supply circuit;
a second circuit forming a second unload circuit branching off a second supply circuit from a second discharge circuit of the pressure fluid source and connecting to the second supply circuit; and the first circuit and the second circuit. A third unload circuit is formed between the first unload circuit and the second unload circuit, and a third circuit having a directional control valve connected to the third supply circuit is provided, and the third circuit is connected to the third unload circuit. A collector valve device is provided between the third supply circuit and the first discharge circuit and the second discharge circuit or the first supply circuit and the second supply circuit, and the collector valve device is directed toward the third supply circuit. A pressure fluid circuit comprising: a check valve that allows flow in the forward direction; and a throttle connected in series to the check valve.