JPS6349013B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides hydraulic power for civil engineering and construction machinery such as hydraulic excavators and hydraulic cranes in which a plurality of hydraulic pumps driven by a plurality of engines and one or more actuators form a hydraulic closed circuit. Regarding circuits.

In large hydraulic excavators, two engines drive two swing pumps, and these two swing pumps supply pressure oil to one or more swing motors. If the hydraulic circuit formed by the swing motor and the swing motor is an open circuit, energy during swing braking cannot be recovered. For this reason, it is already known that the hydraulic circuit is made into a closed circuit to recover energy during swing braking. The first part shows the structure of a typical hydraulic excavator. 1 is an upper rotating body, 2 is a lower traveling body,
3 is a swing ring, 4 is a boom, 5 is an arm, 6 is a bucket, 7 is a boom cylinder, 8 is an arm cylinder, and 9 is a bucket cylinder. FIG. 2 shows a hydraulic circuit of a conventional hydraulic excavator in which the hydraulic circuit of the swing motor 10 that drives the swing wheel 3 is a closed circuit. The two engines 11a, 11b rotationally drive main pumps 13a, 13b, 14a, 14b, pilot pumps 15a, 15b, and double-swivel swing pumps 16a, 16b via pump drive devices 12a, 12b consisting of gears and the like. Main pump 1
3a, 13b are connected to the switching valve group 19a by an open circuit via check valves 17a, 17b, and the main pumps 14a, 14b are connected to the check valve 1
8a and 18b, it is connected to the switching valve group 19b by an open circuit. Switching valve group 19a, 1
Reference numeral 9b denotes a plurality of directional switching valves 19a ₁ to 19a ₃ , 19b ₁ to 19b ₂ that share a common inlet and outlet for pressure oil, and are connected to each other, and the directional switching valve 19a ₁ has an arm cylinder 8, The directional switching valve 19a ₂ has a bucket cylinder 9, the directional switching valve 19a ₃ has a left traveling motor 20a, the directional switching valve 19b ₁ has a boom cylinder 7, and the directional switching valve 19b ₂ has a right traveling motor 20b. , are connected respectively. Each direction switching valve 1
9a ₁ to 19a ₃ and 19b ₁ to 19b ₂ are switched by a pilot pressure signal to control the flow rate, but these pilot pressure signal circuits are omitted in FIG. Rotating pump 16a, 16
b is connected to the swing motor 10 through a closed circuit.
The rotating pumps 16a and 16b are equipped with variable discharge mechanisms 21a and 21b such as swash plates, and variable discharge mechanism 21.
regulators 22a and 22 that control a and 21b;
b. The regulators 22a, 22b are supplied with servo pressure from the pilot pumps 15a, 15b, and are also given a pilot pressure signal from the pilot valve 23. Pilot valve 2
3 has an operating lever 24. This type of regulator generally has a hydraulic servo mechanism, which includes a servo cylinder that operates a variable discharge amount mechanism of a hydraulic pump, and a servo valve that controls the amount and direction of pressure oil supplied to the servo cylinder. It consists of And, servo pressure means pressure oil supplied to the servo cylinder via the servo valve,
The pilot pressure signal means the oil pressure that controls the amount of spool movement of the servo valve.

In FIG. 2, since the hydraulic circuit of the swing motor 10 is a closed circuit, oil returns from the swing motor 10 to the swing pumps 16a, 16b during swing braking, and the swing pumps 16a, 16b are driven as motors. It helps the engines 11a, 11b to rotate, thereby recovering energy. However, in order to reduce the output and use it, one of the engines 11b is sometimes stopped and only one engine 11a is turned, but in this case, since the circuit is closed, the pressure oil from the swing pump 16a stops. The rotating pump 16b is supplied to the rotating pump 16b.
b performs a motor action, and the engine 11b is rotated. This may cause damage to the engine 11b, and may cause the engine 11b to crash at an unexpected time, which is dangerous.

It is an object of the present invention to solve the above-mentioned problems, so that among a plurality of hydraulic pumps driven by individual engines, a stopped hydraulic pump is activated by pressure oil from an operating hydraulic pump. To provide a hydraulic circuit for civil engineering and construction machinery that can prevent the engine from rotating during a stopped state and eliminate the danger caused by the rotation of a stopped engine.

In order to achieve this object, the present invention provides a method for transmitting the discharge pressure of the pilot pump on the same engine side to at least one of the servo pressure circuit and the pilot pressure signal circuit of each regulator of a plurality of hydraulic pumps in one closed circuit. An on-off valve is provided on the discharge side of each pilot pump to make the pressure in the servo pressure circuit or pilot pressure signal circuit zero when there is no pressure.
It is characterized in that each pilot pump is provided with a valve that prevents pressure oil from flowing in from other pilot pumps.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 3 shows a servo pressure cut method according to an embodiment of the present invention. Components similar to those in FIG. 2 are designated by the same reference numerals. Pilot pump 15a, 15b
On-off valves 26a, 26 are connected to the servo pressure circuits 25a, 25b connected to the regulators 22a, 22b.
b are provided respectively. Opening/closing valves 26a, 26b
The working pressure of pilot pump 1 on the same engine side is
5a and 15b, respectively. Open/close valve 2
6a, 26b connect the servo circuits 25a, 25b to the tanks 27a, 27b in the closed circuit state shown in FIG.
Connect to to bring the circuit pressure to zero.

A check valve 28a,
28b are provided respectively to prevent pressure oil from flowing into each other from other pilot pumps.

Note that the swing pumps 16a, 16b correspond to a plurality of hydraulic pumps driven by separate engines in the present invention, the swing motor 10 corresponds to an actuator in the present invention, and the swing pumps 16a, 16b correspond to a plurality of hydraulic pumps driven by separate engines in the present invention.
and the swing motor 10 are connected in a closed circuit.
Further, the on-off valves 26a and 26b correspond to on-off valves of the present invention, and the check valves 28a and 28b correspond to valves for preventing inflow of pressure oil, respectively.

Now, engine 11a is rotating, engine 11b
If the pump 16a and the pilot pump 15a are stopped, the swing pump 16a and the pilot pump 15a are driven, and the swing pump 16b and the pilot pump 15b are stopped. The discharge pressure of the pilot pump 15a is supplied as operating pressure to the pilot valve 23 via the check valve 28a, and also acts as operating pressure on the on-off valve 26a, which resists the spring and switches to the open state. pump 1
The discharge pressure of 5a is used as servo pressure by the regulator 22.
supplied to a. As a result, when the operating lever 24 of the pilot valve 23 is operated, a pilot pressure signal is applied to the regulator 22a, the swing pump 16a discharges oil, and the swing motor 10 rotates.

The pilot pump 15b does not discharge, and the discharge pressure of the pilot pump 15a is cut off by the check valve 28b, so the on-off valve 26b is in a closed state, and the servo pressure circuit 25b is connected to the tank 27.
b, the circuit pressure becomes zero. That is, the servo pressure of the regulator 22b becomes zero, and therefore, even if a pilot pressure signal is applied to the regulator 22b, the regulator 22b does not operate, and the variable discharge amount mechanism 21b is held at a neutral position indicating a zero discharge amount. be done. Therefore, the orbiting pump 16b does not rotate even if it receives the discharge pressure from the orbiting pump 16a.

FIG. 4 shows another embodiment of the present invention, which uses a pilot pressure signal cut method. Components similar to those in FIG. 3 are designated by the same reference numerals. Pilot valve 23
The pilot pressure signal circuit 29a which passes from one output boat through the regulator 22a and returns to the other output boat is provided with an on-off valve 30a, and similarly the pilot pressure signal circuit 29b is provided with an on-off valve 30b. The operating pressure of the on-off valves 30a, 30b is the same as that of the pilot pumps 15a, 15b on the same engine side.
They are taken from each. On-off valves 30a, 30b
corresponds to the on-off valve of the present invention, and in the closed state shown in FIG. 4, the pilot pressure signal circuit 29
a, 29b are short-circuited, and the regulators 22a, 2
The circuit pressure applied to both ends of 2b is made zero.

Now, engine 11a is rotating, engine 11b
is stopped, pilot pump 15
The opening/closing valve 30a is opened by the discharge pressure a, the pilot pressure signal of the pilot valve 23 is sent to the regulator 22a by the pilot pressure signal circuit 29a, and the orbiting pump 16a discharges oil. On the other hand, since there is no discharge pressure from the pilot pump 15b, the on-off valve 30b is closed, the pilot pressure signal circuit 29b is immediately cut off, and the pilot pressure signal given to the regulator 22b becomes zero. As a result, the regulator 22b is held at the neutral position where the discharge amount is zero, and the rotating pump 16b
does not rotate even if it receives pressure oil from the swing pump 16a.

The present invention is not limited to the closed circuit of a swing pump, but can be applied to any closed circuit formed by a plurality of hydraulic pumps driven by individual engines and one or more actuators. Can be done. When using a plurality of actuators, the plurality of actuators are connected in parallel to the hydraulic pump. Further, the present invention is not limited to two engines, but can also be applied to three or more engines.

Furthermore, both the servo pressure cut method and the pilot pressure signal cut method can be used simultaneously.

As explained above, according to the present invention, the discharge pressure of the pilot pump on the same engine is connected to at least one of the servo pressure circuit and the pilot pressure signal circuit of each regulator of a plurality of hydraulic pumps in one closed circuit. An on-off valve is provided on the discharge side of each pilot pump to make the pressure in the servo pressure circuit or pilot pressure signal circuit zero when there is no pressure.
Since each pilot pump is equipped with a valve that prevents pressure oil from flowing in, one of the multiple hydraulic pumps driven by an individual engine can
It is possible to prevent a stopped hydraulic pump from receiving pressurized oil from an operating hydraulic pump to operate a motor, and to prevent a danger caused by a stopped engine rotating. Furthermore, since engine stoppage is detected based on the absence of discharge pressure from the pilot pump, there is no need to provide a separate detection means. Since only one valve is required, costs can be reduced.

[Brief explanation of drawings]

Figure 1 is a side view of a typical hydraulic excavator, Figure 2
The figure is a hydraulic circuit diagram of a hydraulic excavator equipped with a conventional closed circuit, and FIG. 3 is a hydraulic circuit diagram of an embodiment of the present invention.
FIG. 4 is a hydraulic circuit diagram of another embodiment of the present invention. 10...Swivel motor, 11a, 11b...Engine, 15a, 15b...Pilot pump, 1
6a, 16b...Swivel pump, 21a, 21b...
...Variable discharge amount mechanism, 22a, 22b...Regulator, 23...Pilot valve, 25a, 25
b... Servo pressure circuit, 26a, 26b... Open/close valve, 28a, 28b... Check valve, 29
a, 29b...Pilot pressure signal circuit, 30a,
30b...Opening/closing valve.

Claims (1)

[Claims] 1. A plurality of hydraulic pumps driven by individual engines and an actuator operated by supply of pressure oil from the hydraulic pumps are connected in a closed circuit to control the variable discharge amount mechanism of the plurality of hydraulic pumps. Supplying servo pressure for operating the regulator to each regulator from a pilot pump driven by each of the engines, and
A civil engineering project in which pilot valves, which use all pilot pumps as operating pressure sources, give pilot pressure signals that control the operating amount of regulators.
In a hydraulic circuit of a construction machine, when there is no discharge pressure of a pilot pump on the same engine in at least one of the servo pressure circuit and the pilot pressure signal circuit of each regulator, the pressure in the servo pressure circuit or the pilot pressure signal circuit is zeroed. On the discharge side of each pilot pump,
A hydraulic circuit for civil engineering and construction machinery, characterized in that each pilot pump is provided with a valve that prevents pressure oil from flowing in from another pilot pump.