JPS6127607B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic circuit in which an actuator is operated by a single pump, and in which excess oil in the pump is used as a cooling power source to reduce power loss. At the same time, it is characterized by reducing the calorific value of the oil.

As a conventional hydraulic circuit, for example, as described in Hydraulic Valve Handbook (published February 29, 1963, Nikkan Kogyo Shimbun, p. 267, Figure 6.1.30),
Some pumps have a relief valve and a cooler installed in series in a branch line between the pump discharge path and the tank.

The surplus oil released from this relief valve to the tank can be broadly classified into cases where excess oil is generated while the actuator is in operation, and cases where excess oil is generated because the actuator is stopped (pressurized). There is.

In the former case, for example, even if the hydraulic circuit uses a single pump to operate a single actuator, the pump discharge rate should be set to a value higher than the required flow rate of the actuator, and the actuator should be controlled by a flow control valve or the like within the range of the pump discharge rate. If a pump is not available to control the speed and meet the flow rate required by the actuator, a pump with a larger capacity is used, resulting in surplus oil even when the actuator is in operation.

In the latter case, for example, when the cylinder serving as the actuator is stopped at the end of its stroke, the total discharge amount of the pump becomes surplus oil. Conventionally, this surplus oil is controlled by a relief valve and returned to the tank, but all of this surplus oil becomes heat, and as a result, only the generated heat results in power loss. Furthermore, in order to deal with the residual heat of the oil, a cooler is used to cool the oil, but power for operating the cooler is required.

The present invention was invented in view of the above points, and by effectively utilizing surplus oil as a power source for operating the cooler, the surplus oil released from the relief valve to the tank is reduced, reducing power loss. ,
The purpose of this is to cool excess oil in the tank with a cooler driven by the above power source.

To achieve this objective, the hydraulic circuit of the present invention has an actuator 5 connected to the discharge line 2 of the pump 1.
a flow control valve 3a for adjusting the speed of the actuator 5a, and a branch line 15 branching from the discharge line 2,
It consists of a relief valve 16 that regulates the pressure of the actuator 5a, and a cooler 17 is connected to the secondary side of the relief valve 16, and a cooling valve is connected to the mainstream line 2a branching from the discharge line 2 via a pressure reducing valve 6. A power machine 8 is connected, and the power machine 8 is used for supplying a heat absorption medium to the cooler 17, and the flow control valve 3
When the speed of the actuator 5a is controlled in step a, excess oil is released from the relief valve 16 to the tank. At this time, a part of the surplus oil is supplied to the cooling motor 8 via the pressure reducing valve 6, and the actuator 5a is
and the power machine 8 are simultaneously driven. When the actuator 5a stops and the entire discharge amount of the pump 1 is released from the relief valve 16 to the tank, a portion of the excess oil is supplied to the motor 8 via the pressure reducing valve 6 to drive it. In this way, the motor 8 driven by the surplus oil operates the cooler 17, and the cooler 17 cools the surplus oil released from the relief valve 16 to the tank.

Embodiments of the present invention will be described below based on the drawings.

In the illustrated embodiment, a plurality of main lines 2a, 2b, 2c, and 2d are branched in parallel from the discharge line 2 of the pump 1, and among these, three main lines 2b, 2c,
Flow control valves 3a and 3 are installed at 2d, respectively.
b, 3c, directional control valves 4a, 4b, 4c, and actuators 5a, 5b, 5c, while a cooling motor is connected to the remaining main line 2a via a pressure reducing valve 6 and an electromagnetic directional control valve 7. 8 is connected. By installing this pressure reducing valve 6, the pressure in the discharge line 2 which is the primary side of the pressure reducing valve 6 is set to the set pressure of the relief valve 16, and the pressure on the secondary side is set to the set pressure of the pressure reducing valve 6. When actuators 5a to 5c are activated simultaneously, actuators 5a to 5c
The actuators 5a to 5c can be operated without being affected by the operation of the motor 8 whose load is lighter than that of the motor 8. As a result, the pressure reducing valve 6 prevents oil from being supplied intensively toward the motor 8 with the least load, thereby ensuring the operation of each actuator 5a to 5c. The power machine 8 has a central large-diameter cylinder 9a and small-diameter cylinders 9b, 9 on both sides.
b are arranged coaxially, and each piston 10a, 10 provided in each of these cylinders.
b, 10b are connected by one rod 11, and the A port A and the B port B of the 3-position 4-port electromagnetic directional control valve 7 are connected to the small diameter Cylinder 9b, 9b
is connected to.

On the other hand, a branch line 15 is branched from the discharge line 2 of the pump 1 to the tank 14a, and a relief valve 16 and a cooler 17 are interposed in series in the branch line 15. Further, the lines 21a and 21b connected to the chambers 19 and 20 on both sides of the piston 10a of the large-diameter cylinder 9a in the power machine 8 are combined into one via check valves 22a and 22b, respectively, and the condenser 23 and the pressure reducer 24 , a cooler 17, and a refrigerant circuit connected to the chambers 19 and 20 in a closed loop via check valves 25a and 25b, respectively.

The illustrated embodiment is configured as described above,
The action will be explained below.

In FIG. 1, when the three directional control valves 4a to 4c are switched to a position other than the neutral position and the pump 1 is driven, the fluid discharged from the pump 1 is adjusted according to the opening degree of each flow control valve 3a to 3c. is supplied to three actuators 5a to 5c, and actuates these actuators 5a to 5c. In this case, since all the actuators 5a to 5c are operated, almost no surplus oil is generated to drive the motor 8. However, for example, the second
As shown in the figure, during one cycle, when two actuators 5a and 5b are stopped, or when all actuators 5a, 5b, and 5c are stopped, surplus oil is always generated. That is,
Of the three directional control valves 4a to 4c, two directional control valves 4a and 4b are set to the neutral position, and the other directional control valve 4c is switched to direct the fluid in the discharge line 2 through the flow control valve 3c. When the actuator 5c is supplied to the actuator 5c, the supply flow rate Q1 to the actuator 5c and the discharge flow rate Qp of the pump 1 are Q1.
Since the relationship is <Qp, surplus oil is generated and is bypassed to the tank 14a via the relief valve 16. At this time, the electromagnetic directional control valve 7 is switched to supply excess oil to the motor 8 via the pressure reducing valve 6. However, since the load on the motor 8 is smaller than the load on the actuator 5c, the pressure reducing valve 16 Reduce the pressure in line 2. The motor 8 operates with the reduced pressure. When the power machine 8 and the actuator 5c are operated equally in this way, the pressure reducing valve 6 maintains the pressure of the discharge line 2, which is the primary side of the pressure reducing valve 6, at the set pressure of the relief valve 16, while the pressure of the power machine on the secondary side is maintained. 8 is operated at a low pressure corresponding to the set pressure of the pressure reducing valve 6.

To explain the operation of the power machine 8, the power machine 8
If surplus oil is supplied to the right cylinder 9b among the small cylinders 9a and 9b that make up the
As the piston 10a moves to the left, the refrigerant in the left chamber 19 pushes open the check valve 22a and is sent to the cooler 17 via the condenser 23 and pressure reducer 24. The flow rate of refrigerant in the cooling circuit is determined by pressure reducer 2.
Since it is regulated almost constant by resistance such as 4,
Naturally, the operating speed of the piston 10a is also determined,
The surplus oil generated there is cooled by the cooler 17 while being returned from the relief valve 16 to the tank 14a. The refrigerant that has exchanged heat with the excess oil in the cooler 17 is sucked into the right chamber 20 via the check valve 25b. When the displacement movement of the rod 11 reaches the end and the micro switch 26a is closed, the electromagnetic directional control valve 7 is switched by an electric signal, so that, in contrast to the above, the refrigerant in the right chamber 20 is transferred to the cooler 17. The micro switch 26b on the other side is operated at the end thereof, and the electromagnetic directional control valve 7 is switched. In this way, the cooling motor 8 is operated even with the surplus oil, and the refrigerant is circulated within the cooling circuit.

When the actuator 5c reaches the end of its stroke, the total discharge amount of the pump 1 becomes surplus oil, but part of this surplus oil is effectively used by the motor 8, and as a result, the surplus oil is released from the relief valve 16 to the tank. becomes less.

That is, in the embodiment described above, since the cooling motor 8 was provided in one of the plurality of main lines, and the actuators 5a, 5b... were provided in the remaining main lines, the number of stops of each actuator 5a, 5b... Accordingly, surplus oil is generated, and if the operating cycle of the cooling power machine 8 is increased or decreased in response to the surplus oil, power loss can be further reduced. Further, since excess oil is cooled by the cooler 17 operated by the cooling motor 8, the amount of heat generated can be reduced, and the overall power loss can be reduced.

Furthermore, in the embodiment described above, since the piston-type accumulator cooling motor 8 is used, which is configured to introduce refrigerant into the large-diameter cylinder 9a and excess oil into the small-diameter cylinders 9b, 9b, a small capacity surplus is used. The cooling motor 8 can be operated with oil.
As a result, even if the amount of surplus oil is small, a cooling circuit with a large cooling effect can be constructed.

Further, in the above embodiment, the circuit is configured by four main lines, but the circuit is not limited to this, and any number of two or more main lines can satisfy the functions of the present application. .

Although the cooling power machine of the embodiment corresponds to a so-called piston type accumulator, it goes without saying that a diaphragm type accumulator may also be used. Furthermore, in practice, a rotary compressor may be used as the power machine 8. Further, although the cooling device in the embodiment is a refrigerant compression type, if the cooler 17 is an air cooling type, the motor 8 is a fan motor, and the cooler 1
When the motor 7 is water-cooled, the motor 8 corresponds to a pump for circulating cooling water.

As described above, the present invention is directed to the discharge line 2 of the pump 1.
A flow control valve 3a is connected to an actuator 5a to adjust the speed of the actuator 5a, and a relief valve 16 is interposed in a branch line 15 branching from the discharge line 2 and regulates the pressure of the actuator 5a. , a cooler 17 is connected to the secondary side of the relief valve 16, and a cooling motor 8 is connected to the main line 2a branching from the discharge line 2 via a pressure reducing valve 8, while the motor 8 is connected to the cooler 17. When the speed of the actuator 5a is controlled by the flow control valve 3a, excess oil is supplied to the relief valve 16.
is released into the tank. At this time, a part of the surplus oil is supplied to the cooling motor 8 via the pressure reducing valve 6,
Actuator 5a and power machine 8 are driven simultaneously. Even when the entire discharge amount of the pump 1 is released from the relief valve 16 to the tank due to the stop of the actuator 5a, a portion of the excess oil is supplied to the motor 8 via the pressure reducing valve 6 to drive it. In this way, the motor 8 can be driven with a portion of the surplus oil, and the remaining surplus oil can be cooled by the motor 8. In other words, since the power that would normally become heat is used as the power source for the cooling power machine 8, power loss is reduced, and heat generation by the amount of power used can be prevented, and the overall amount of heat generation is reduced.
Furthermore, since the heat generated by the remaining surplus oil is cooled with such power, the cooling efficiency is good, and there are also effects such as the ability to completely eliminate the consumption of power dedicated to cooling, which was originally required separately.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the operation of an actuator. 1... Pump, 2... Discharge line, 2a... Mainstream line, 3a... Flow control valve, 5a
... Actuator, 6 ... Pressure reducing valve, 8 ... Cooling motor, 15 ... Diversion line, 16 ... Relief valve, 17 ... Cooler.

Claims (1)

[Claims] 1 Actuator 5 is connected to discharge line 2 of pump 1.
a flow control valve 3a for adjusting the speed of the actuator 5a, and a branch line 15 branching from the discharge line 2,
It consists of a relief valve 16 that regulates the pressure of the actuator 5a, and a cooler 17 is connected to the secondary side of the relief valve 16, and a cooling valve is connected to the mainstream line 2a branching from the discharge line 2 via a pressure reducing valve 6. A hydraulic circuit characterized in that a power machine 8 is connected, and the power machine 8 is used for supplying a heat absorption medium to the cooler 17.