JPH078884Y2 - Hydraulic system of injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a hydraulic device of an injection molding machine, and more particularly to improvement of a hydraulic oil purification circuit of a hydraulic circuit using a variable discharge pump as a drive source.

<Prior Art> A conventional hydraulic circuit will be described with reference to FIG. 3. Numeral 11 is a variable discharge pump that pumps up hydraulic oil 14 in an oil tank 13 through a suction filter 12 as high pressure oil through a control valve 15. It acts on the hydraulic motor 16. The return oil from the hydraulic motor 16 returns to the hydraulic tank 13 via the line 17 and the oil cooler 18. At this time, the case drain of the variable discharge pump 11 is directly discharged from the conduit 19 to the hydraulic tank 13. In addition, a circulation circuit is provided for purifying hydraulic oil,
A hydraulic pump (for example, a trochoid pump) 20 that works in conjunction with the variable discharge pump 11 sucks hydraulic oil 14 from an oil tank 13 and discharges it from a return circuit 23 through a filter 21. It is designed to purify hydraulic oil. 22 is a relief valve provided as a safety valve.

<Problems to be solved by the invention> However, the variable discharge pump is very sensitive to the contamination of the hydraulic oil, and the strict control of the hydraulic oil is required. The case drain discharges the operating oil polluted at a relatively high temperature into the oil tank.

The object of the present invention is to eliminate the above-mentioned drawbacks and to provide a purification circuit in which the hydraulic oil is not contaminated.

<Means for Solving the Problem> In order to achieve the above-mentioned object, a variable discharge pump that operates an actuator and a hydraulic pump that operates in conjunction with the operation of the variable discharge pump are provided, and the hydraulic pump is an oil pump. In the hydraulic device of the injection molding machine, which comprises an oil purifying circuit that sucks hydraulic oil from the tank and discharges it to the oil tank via a heat exchanger through a filter provided in the return circuit and a check valve downstream thereof, the variable discharge A case drain circuit of a quantity pump is connected to a suction side circuit of the hydraulic pump of an oil purifying circuit to provide a hydraulic system of an injection molding machine.

<Operation> The case drain of the variable discharge pump that has become dirty at high temperature is now returning to the oil tank via the purification circuit.

<Embodiment 1> One embodiment of the present invention will be described with reference to FIG. In the description, the same members as those of the conventional circuit are designated by the same reference numerals, and the description thereof will be omitted. The case drain 26 of the variable discharge pump 11 is connected to the suction circuit of the purification circuit circulation hydraulic pump 20 so that the waste oil of the case drain 26 contaminated by high temperature does not directly return to the oil tank 13 but goes through the purification circuit. While returning to 13,
An oil cooler 25 for cooling the high-temperature hydraulic oil from the case drain 26 is incorporated in the return circuit 23 of the purification circuit.

<Effect 1> With the above-described configuration, the working oil contaminated by the high temperature of the case drain is returned to the oil tank through the purification circuit.

<Embodiment 2> Another embodiment of the present invention will be described with reference to FIG. In the description, like the first embodiment, the description of the members described in the conventional circuit will be omitted, and only the changed parts will be described. In this embodiment, an actuator (hydraulic motor 16) is provided in the return circuit 23 of the purification circuit.
Is connected to the oil cooler 29 of the return circuit 23 of the purification circuit, the return oil from the actuator for the return oil from the return line 17 and the purification oil for the return oil of the actuator are used together. A filter 28 is provided in the return line 17, and a check valve 27 is provided so that the return oil from the actuator side does not flow back into the purification circuit.

<Effect 2> Since it is configured as described above, all the contaminated hydraulic oil is
Since it is returned to the oil tank via the purification circuit, it is efficient and
The hydraulic oil in the oil tank is less likely to be contaminated. Also, the high temperature return oil from the actuator is cooled.

<Effects of the Invention> The hydraulic device of the present invention uses the hydraulic pump that operates in conjunction with the variable discharge pump to operate the hydraulic oil and the case drain of the variable discharge pump while the variable discharge pump is operating.
Purification and cooling can be forced by constantly passing through the filter and heat exchanger.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment according to the present invention. FIG. 2 is a view showing another embodiment according to the present invention. FIG. 3 is a circuit diagram according to the conventional method. 11… Variable discharge pump, 13… Oil tank, 15… Control valve, 16…
Hydraulic motor, 17 ... Return line, 20 ... Hydraulic pump, 21, 28 ... Filter, 22 ... Relief valve, 23 ... Return circuit, 25, 29 ... Oil cooler

Claims (1)

[Scope of utility model registration request] 1. A variable discharge pump 11 for operating an actuator 16 and a hydraulic pump 20 which operates in conjunction with the operation of the variable pump 11, the hydraulic pump 20 being an oil tank.
The hydraulic pressure of the injection molding machine that constitutes the oil purification circuit that sucks the hydraulic oil 14 from the filter 13 and discharges it to the oil tank 13 via the heat exchanger 29 via the check valve 27 and the filter 21 provided in the return circuit 23. In the apparatus, a case drain circuit 26 of the variable discharge pump 11 is connected to a suction side circuit of the hydraulic pump 20 of an oil purification circuit, which is a hydraulic apparatus of an injection molding machine.