JPH07334247A - Temperature controller for hydraulic oil - Google Patents

Abstract

PURPOSE:To control a hydraulic oil of a hydraulic equipment or the like to appropriate temperature in a short time and to keep the appropriate temperature. CONSTITUTION:This controller is constituted so that an oil cooler 15 is connected to a pressure control valve 14 in parallel at the downstream part of a hydraulic circuit. A piston 14b is provided at a spring 14a of the pressure control valve 14, and an electromagnetic proportional pressure-reducing valve 21 and a pilot pump 22 are connected through a pilot oil duct 23 between the piston 14b and an acting oil tank 17. Then, a temperature sensor 19 is arranged at the hydraulic oil tank 17, a control part 20 is connected to the temperature sensor 19 and the control part 20 is connected to the electromagnetic proportional pressure-reducing valve 21. When the control part 20 outputs a current value I1 to the electromagnetic proportional pressure-reducing valve 21 based on the value detected by the temperature sensor 19 and the previously set target temperature, pilot pressure from the pilot pump 22 is added to spring force F of the spring 14a of the pressure control valve 14, and the quantity of the hydraulic oil to be allowed to flow into the oil cooler 15 is increased or decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device for hydraulic oil, and more particularly to a temperature control device for hydraulic oil which brings the hydraulic oil to a proper temperature in a short time and maintains the proper temperature. It is about.

[0002]

2. Description of the Related Art A conventional cooling device for hydraulic oil of this type is shown in FIG.
Follow the instructions below. In the figure, reference numeral 1 is a hydraulic pump, and hydraulic oil discharged from the hydraulic pump 1 passes through an actuator such as a directional control valve 2 and an arm cylinder 3, and a pressure control valve 4 arranged in parallel. And the oil cooler 5 and are returned to the tank 6. A spring 4a is arranged in the pressure control valve 4, and the spring 4a
Urges the pressure control valve 4 with a constant spring pressure.
As a result, the hydraulic oil passes through the pressure control valve 4 or the oil cooler 5 at a constant flow rate and is returned to the tank 6.

[0003]

A conventional hydraulic oil cooling device is provided with a pressure control valve in parallel with the oil cooler, and the oil cooler is operated by the pressing force of a spring provided in the pressure control valve. It is configured such that the flow rate of the hydraulic oil passing through is constant. Therefore, even when the outside air temperature is high or low, a fixed amount of the working oil is always flowed into the oil cooler to be cooled. Therefore, when the outside air temperature is low, since a certain amount of the hydraulic oil in a low temperature state is further cooled by the oil cooler at the time of starting, it takes a long time to warm up, so that the start of the work is delayed and Since the oil temperature of does not rise sufficiently, it causes a delay in the response of the actuator.
Further, since the temperature of the hydraulic oil is low, the viscosity of the hydraulic oil is high, so that the frictional resistance when flowing in the hydraulic circuit is high and the power loss is increased.

Further, when the outside air temperature is high, a certain amount of hydraulic oil flows into the oil cooler even when the temperature of the hydraulic oil rises, and therefore the cooling capacity becomes constant, The hydraulic oil may exceed the allowable temperature. Therefore,
When the temperature of the hydraulic oil rises, the viscosity decreases, and the functions of the valves and the pump efficiency decrease. Therefore, the working fluid of hydraulic equipment or the like is brought to an appropriate temperature in a short time, and a technical problem to be solved in order to maintain the appropriate temperature arises, and the present invention aims to solve the problem. To aim.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been proposed in order to achieve the above-mentioned object, and is an oil pressure operation in which an oil cooler is provided in a hydraulic circuit and a pressure control valve is connected in parallel with the oil cooler. In the oil cooler circuit of oil, a piston is provided in the spring of the pressure control valve, and an electromagnetic proportional pressure reducing valve and a pilot pump are connected between the piston and the hydraulic oil tank via a pilot oil passage, A temperature sensor is provided in the hydraulic oil tank, and a control unit that outputs a current based on a detection value of the temperature sensor and a preset target temperature,
A temperature control device for hydraulic fluid connected to the electromagnetic proportional pressure reducing valve is provided.

[0006]

The pilot oil passage is connected to the piston provided in the spring of the pressure control valve of the temperature control device of the present invention, and the electromagnetic proportional pressure reducing valve is provided in the pilot oil passage. The pilot oil pressure is increased or decreased, and the pilot oil pressure is added to the spring whose spring pressure is set to a small value in advance. Therefore, the control unit compares the temperature of the hydraulic oil in the tank detected by the temperature sensor with a preset target temperature to calculate the temperature difference, and the current value corresponding to the temperature difference is calculated as the electromagnetic value. When output to the proportional pressure reducing valve, the pilot hydraulic pressure from the pilot pump is increased and added to the spring pressure of the spring of the pressure control valve when the temperature of the hydraulic oil is higher than the target temperature. On the other hand, when the temperature of the hydraulic oil is lower than the target temperature, the pilot hydraulic pressure is reduced and added to the spring pressure of the pressure control valve.

When the pressure of the pressure control valve is increased, the amount of hydraulic oil passing through the oil cooler is increased, so that the hydraulic oil is cooled and reaches the target temperature.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. In FIG. 1, the directional control valve 13 for the arm cylinder 12 is connected to the hydraulic circuit system of the hydraulic pump 11. Then, the pressure control valve 1 is provided downstream of the direction control valve 13.
4 and an oil cooler 15 such as an oil cooler are connected in parallel and connected to the tank 17. The hydraulic fluid discharged from the hydraulic pump 11 is returned to the tank 17 via the pressure control valve 14 or the oil cooler 15. In addition, a temperature sensor 19 is attached to the tank 17 at the input position of the hydraulic pump 11.
And connecting the temperature sensor 19 to the controller 20 and connecting the controller 20 to the electromagnetic proportional pressure reducing valve 21.
Further, the electromagnetic proportional pressure reducing valve 21 is connected to the pilot pump 22. Then, the spring 1 of the pressure control valve 14
4a is provided with a piston 14b, and the spring 14a
The spring force F is set to a smaller spring force than the spring arranged in the pressure control valve of the conventional example. And the piston 1
The electromagnetic proportional pressure reducing valve 21 is connected to 4b via a pilot oil passage 23 to form a temperature control device 24.

As shown in FIG. 2, the flow rate of the hydraulic oil passing through the oil cooler 15 and the pressure control valve 14 is determined by the oil cooler 15
Is determined by the pressure loss curve K and the override characteristic curve of the pressure control valve 14. When the pilot pressure P of the pressure control valve 14 is set to 0, the pressure control valve 14
Is obtained an override characteristic curve B ₁ in which only the spring force F of the spring 14a is urged.
A hydraulic fluid having an oil quantity of Q ₁ is passed through. When the maximum pilot pressure P _b is applied to the pressure control valve 14,
The pressure control valve 14 obtains an override characteristic curve B ₂ urged by the sum of the spring force F and the pilot pressure P _b . Then, the hydraulic oil of the oil amount Q ₂ is passed through the oil cooler 15. And Thus, the pilot pressure P of the pressure control valve 14 by changing from 0 to P _b, you are possible to vary the flow rate of the hydraulic oil passing through the oil cooler 15 from Q ₁ to Q _2.

FIG. 3 is a flow chart showing the processing sequence of the temperature control apparatus for hydraulic oil according to the present invention. In the figure, the temperature sensor 19 detects the current temperature T ₁ of the hydraulic oil and sends it to the controller 20 (step 101). The controller 20 compares the preset target temperature T _O with the current temperature T ₁ (step 102). The present temperature T
_{If 1} is greater than the target temperature T _O , step 103
Move to.

The control unit 20 outputs a current value I ₁ corresponding to the temperature difference T _O -T ₁ to the electromagnetic proportional pressure reducing valve 21, and the electromagnetic proportional pressure reducing valve 21 changes the pilot pressure P of the pilot pump 22 to the current value I. _The pressure is increased according to ₁ (step 103).
When the pilot pressure P of the pilot pump 22 is increased, the flow rate of the working oil passing through the pressure control valve 14 becomes small and the flow rate of the working oil passing through the oil cooler 15 becomes large ( Step 104). Since the flow rate of the working oil cooled by the oil cooler 15 is increased, the temperature T _{1 of the} working oil is lowered (step 105). Then, after a lapse of a certain time, the process returns to step 101.

On the other hand, at step 102, the current temperature T₁But
Target temperature T_OIf smaller, move to step 106
And the control unit 20 controls the temperature difference T₁-T_OCurrent equivalent to
Value I ₂To the electromagnetic proportional pressure reducing valve 21,
The valve 21 is a pilot pressure P of the pilot pump 22.
Current value I₂The pressure is reduced accordingly (step 106). The
The pilot pressure P of the pilot pump 22 is reduced.
And the flow rate of hydraulic oil passing through the pressure control valve 14 is large.
And the flow of hydraulic oil passing through the oil cooler 15.
The amount becomes small (step 107). And the hydraulic oil is
The flow rate cooled by the oil cooler 15 is reduced.
And the temperature T of the hydraulic oil₁Is raised (step 10
8).

As described above, the temperature control device for hydraulic oil according to the present invention detects the temperature T _{1 of the} hydraulic oil by the temperature sensor 19 every time a fixed time elapses, and the temperature T ₁ and the hydraulic oil are appropriate. It compares the target temperature T _O of brought operating in, by performing the processing procedure described above, it is possible to bring the temperature of the hydraulic oil to a temperature T _O of the target. The present invention can be modified in various ways without departing from the spirit of the present invention.
And, it goes without saying that the present invention extends to the modified one.

[0014]

As described in detail in the above one embodiment, the present invention increases or decreases the pilot pressure added to the spring pressure of the spring of the pressure control valve in accordance with the temperature of the hydraulic oil of the hydraulic equipment. The amount of hydraulic oil passing through the oil cooler can be changed. Therefore, the working oil can reach the target temperature in a short time, and the working oil can be maintained at the target temperature.

Thus, since the operating oil is maintained at an appropriate operating temperature, the viscosity of the operating oil is kept in a favorable small state, the pressure loss is reduced, the energy saving and the power efficiency are effective. Available. Further, since the working oil is not allowed to flow into the oil cooler during cold weather, the temperature of the working oil is raised in a short time, so that the warm-up time can be shortened and the response delay of the actuator can be eliminated.

Further, when the outside air temperature is high, the oil amount of the working oil flowing into the oil cooler is increased, so that the possibility that the working oil exceeds the allowable temperature is eliminated. It is an invention that exhibits various kinds of effects such as improvement in durability of devices.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the pressure of a pressure control valve and the amount of hydraulic oil flowing into an oil cooler.

FIG. 3 is a flowchart showing a processing sequence of a temperature control device for hydraulic oil.

FIG. 4 is a hydraulic circuit diagram showing a conventional example.

[Explanation of symbols]

 14 Pressure Control Valve 14a Spring 14b Piston 15 Oil Cooler 17 Tank 19 Temperature Sensor 20 Control Section 21 Electromagnetic Proportional Pressure Reduction Valve 22 Pilot Pump 23 Pilot Oil Path 24 Temperature Control Device

Claims (1)

[Claims] 1. In an oil cooler circuit for hydraulic oil in which an oil cooler is provided in a hydraulic circuit and a pressure control valve is connected in parallel with the oil cooler, a piston is provided in a spring of the pressure control valve, An electromagnetic proportional pressure reducing valve and a pilot pump are connected between the piston and the hydraulic oil tank via a pilot oil passage, and a temperature sensor is arranged in the hydraulic oil tank, and a detection value of the temperature sensor and a preset value are set. A temperature control device for hydraulic fluid, wherein a control unit that outputs a current based on the set target temperature is connected to the electromagnetic proportional pressure reducing valve.