JP2000074012A - Hydraulic circuit structure for power vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce viscosity of oil to smoothly let flow oil even in the case of low temperature by providing an oil heating means on the input side of a bubble removing device provided between a pressure-oil tank and a pump or on the bubble removing device itself. SOLUTION: A bubble removing device 4 is provided between a suction filter 36 and a hydraulic pump 2, and constituted so as to remove bubbles by utilizing the vortex current of pressure-oil. The suction filter 36 sucks working oil from a hydraulic tank 1 by the hydraulic pump 2. In this constitution, a heater 5 heating oil is provided on the circuit on the input side of the bubble removing device 4, namely on the input part of the suction part of the suction filter 36. Or, the heating means is provided on the bubble removing device 4 itself. Hereby, viscosity of oil is reduced to quicken flow speed of oil. As a result, oil flows smoothly in the bubble removing device 4, and hence the bubbles are easily removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit structure of a power vehicle such as an agricultural tractor or a construction machine, and more particularly to a technique for efficiently operating a bubble removing device for removing bubbles contained in hydraulic oil. It is something you want to do.

[0002]

2. Description of the Related Art Conventionally, various hydraulic devices such as tractors also use lubricating oil in a transmission case as oil for operating hydraulic equipment.
Oil is agitated by the rotating gear, and bubbles are easily generated. When the air bubbles are sucked into the suction filter and flow into the hydraulic pump again, the air bubbles may interfere with each other to cause unpleasant noise, so-called air squeal, or malfunction of the hydraulic device.

On the other hand, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 10-9 / 1998.
An application for removing these bubbles using a bubble removing device as disclosed in Japanese Patent No. 4304 is filed.

[0004]

However, in the above-mentioned conventional apparatus, when the engine is started and the transmission mechanism is driven in a low temperature area or a low temperature time, for example, the oil viscosity is high, so that the oil viscosity is high. There is a problem that the flow of oil in the bubble removing device is poor and it is difficult to remove bubbles.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has a hydraulic circuit structure for a power vehicle as follows. That is, in a power vehicle in which the hydraulic oil in the hydraulic tank 1 is sucked and supplied to each hydraulic device 3 by the hydraulic pump 2, an oil passage between the hydraulic tank 1 and the pump 2 is provided.
Means 5 for generating a vortex and collecting and discharging air bubbles at a suction portion of the vortex, and heating the oil to the upstream side of the oil path flowing into the air bubble removal apparatus 4 or to the air bubble removal apparatus 4 itself; A hydraulic circuit structure for a powered vehicle, comprising:

[0006]

According to the hydraulic circuit structure of the power vehicle constructed as described above, since the means for heating oil is provided on the input side of the bubble removing device 4 or on the bubble removing device 4 itself, the oil passes through the device 4. The viscosity of the oil is reduced, so that the oil flows smoothly and bubbles are easily removed.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. Reference numeral 10 in FIG. 2 denotes an agricultural tractor, which is an example of a powered vehicle, which includes a front wheel 11 and a rear wheel 12, and transmits a rotational power of an engine 13 mounted on a frame 25 in a front part of the fuselage to a transmission mechanism ( The main transmission 15 and the auxiliary transmission 16) are appropriately decelerated and transmitted to the front wheels 11 and the rear wheels 12.

The main transmission 15 and the auxiliary transmission 16
Are composed of synchromesh gears, and the main transmission 15 can perform a four-speed shift and the auxiliary transmission 16 can perform a two-speed shift. Reference numeral 17 denotes a forward / reverse switching device for changing the traveling direction of the body, which is configured to rotate the forward / backward switching lever 18 in the forward / backward direction to advance or reverse the body.

A cylinder case 19 is mounted on an upper portion of the transmission case 1 at the rear of the vehicle body, and lift arms 20, 20 for lifting and lowering the working machine are pivotally mounted on both left and right sides thereof. A single-acting hydraulic cylinder 3 serving as a hydraulic device is provided in the cylinder case 19, and when hydraulic oil is supplied to or discharged from the cylinder 3, the piston portion expands and contracts, and the lift arms 20, 20 rotate upward. , Or rotate downward.

The cylinder 3 operates by selectively energizing a solenoid of a proportional control valve for ascending or descending according to an energizing command from a controller 24. A hydraulic operating lever 30 is provided on the side of the cockpit 29, and a potentiometer (not shown) is provided at the rotation base of the operating lever 30.
The lift base is provided with a lift arm angle sensor 31 at the turning base. Then, the value of the current supplied to the solenoid of the proportional control valve is changed according to the difference between the value set by the potentiometer and the value detected by the lift arm angle sensor 31, and the current value of the working machine 32 connected to the three-point link mechanism is changed. Elevation control is performed.

The hydraulic circuit configuration of the tractor 10 will be described.
A suction filter 36 is attached to the side, and the suction filter 36 sucks hydraulic oil from the same case 1 also serving as the oil tank 1 via a pipe 37a by a hydraulic pump 2 provided on the lower side of the circuit. It has a structure.

As shown in FIG. 1, the suction filter 36 has a structure in which a heater serving as a means for heating pressure oil is connected in series to the input section. A current flows through the heating wire for a fixed time according to the command, and heat is generated to raise the temperature of the hydraulic oil. As a result, the temperature of the pressure oil passing through the filter 36 increases, and the viscosity decreases.

The hydraulic oil discharged from the suction filter 36 reaches the hydraulic pump 2 via an air bubble removing device 4 described later. The hydraulic pump 2 is driven by the rotational power of the engine 13, and is configured such that high-pressure hydraulic oil is sent from the hydraulic pump 2 to the hydraulic pressure raising / lowering proportional control valve. The bubble removing device 4 is provided between the suction filter 36 and the hydraulic pump 2, and is configured to remove bubbles using a vortex of oil. Referring to FIGS. 4 and 5, the device 4 is disposed in a cylindrical case 40, a conical cyclone chamber 41 having a ventilation hole therein, and a central portion thereof. A small-diameter bubble removing pipe 42 and a swirling flow chamber 4 provided at the bottom.
3 and so on.

The swirling flow chamber 43 has a working oil inflow hole 44, and is configured to change the working oil entering through the working oil inflow hole 44 into a tangential swirling flow. Therefore, when the hydraulic oil containing air bubbles enters through the hydraulic oil inflow hole 44, the hydraulic oil is guided to the cyclone chamber 41, where the air bubbles are removed, and then the hydraulic oil flows from the outflow hole 45 through the pipe 37b. It is led to the hydraulic pump 2.

The air bubbles collected in the center of the cyclone chamber 41 enter the air bubble removal pipe 42 through a number of small holes, and are discharged from the air bubble outlet 46. The bubbles discharged from the bubble outlet 46 are collected in the transmission case 1 through the bubble return path 46 shown in FIG. A proportional control valve is attached to the hydraulic cylinder case 19, and a return port 47 of the proportional control valve and a tank port 48 formed in the hydraulic cylinder case 19 are connected by a rubber hose 49. A return circuit 50 is formed, and the return circuit 50 and the bubble return circuit 46 of the bubble removing device 4 are connected by a rubber hose 51.

Reference numeral 52 denotes a rubber hose 51 from the bubble removing device 4 and a return circuit 5 on the hydraulic cylinder case 19 side.
0 is a negative pressure generator provided at a portion where
The negative pressure generator 52 is provided with a throttle therein, and is configured to generate a negative pressure by increasing the flow velocity of the fluid passing therethrough. Next, the flow of the pressure oil of the tractor 10 and the operation of the bubble removing device 28 will be described.

When the hydraulic pump 2 is rotationally driven by the rotational power of the engine 13, the hydraulic oil discharged from the hydraulic pump 2 reaches the proportional control valve, and is supplied or discharged into the hydraulic cylinder 3 by the action of the control valve. Then, the lift arms 20, 20 are vertically moved. Thereafter, the pressure oil is discharged into the transmission case 13 and stored in the transmission case 13 as lubricating oil for the gears of the transmission mechanism. The pressure oil is heated by the heater 5 via a pipe 37a provided at a lower portion of the case 13, and is guided to the suction filter 36 in a state of reduced viscosity. After that, it is input to the bubble removing device 4.

The pressurized oil containing air bubbles that has entered the swirling flow chamber 43 of the air bubble removing device 4 is guided to the cyclone chamber 41 and narrows the flow path. Outflow hole 4 discharged outside the cyclone chamber
5 is led to the hydraulic pump 2 side. The air bubbles collected in the suction part of the air bubble removal pipe 42 are discharged from the air outlet 46 to the outside of the cylindrical case 40, and then merge with the return circuit 50 by the rubber hose 51. As a result of the hydraulic oil discharged from the proportional control valve being throttled by the negative pressure generator 52, the flow velocity flowing therethrough is increased, and the bubbles collected by the rubber hose 51 are positively sucked into the return circuit 50,
It will be collected in the mission case 19.

In the hydraulic circuit structure of the tractor 10 configured as described above, the bubbles present in the pressure oil sucked from the transmission case 1 do not reach the hydraulic pump 2 but are collected in the case 1. The problem that the hydraulic pump 1 bites air to cause a so-called air squeal phenomenon is eliminated. In addition, a heater 5 for heating oil is provided in a circuit on the input side of the bubble removing device 4, that is, an input portion of the suction filter 36.
Is provided, the viscosity of the oil is reduced and the flow velocity of the oil is also increased, so that the oil flows smoothly into the device 4 to easily remove bubbles.

Next, an embodiment in which the means for heating the oil is provided in the bubble removing device 4 itself will be described. In this case, similarly to the suction filter, a configuration may be adopted in which a heater is provided in the case 40 or the circuit of the bubble removing device 4, but in this case, as shown in FIG.
Is configured to use the heat generated by the driving of the motor.

Referring to FIG. 6, a detailed description will be given of the side of the engine 13, specifically, the circuit 55 of the engine cooling water.
A bracket 56 is provided on the side of the air bubble removing device 4 and the air bubble removing device 4 integrally formed with the oil cooler is sandwiched between the brackets 56.
The cooling water is drawn into the cooler 57 and circulated through the cooler. In addition, the bubble removing device 4
As shown in FIG. 6B, the cooler 57 is provided adjacent to the pressure oil discharge side.

As a result, the air bubble removing device 4 is
The oil which is heated by the cooling water of No. 3 and input to the device 4 has a low viscosity. For this reason, as described above, it is not necessary to separately provide a heater or the like, so that the production cost can be reduced. Further, since the oil cooler 57 is arranged on the side of the engine, the temperature of the hydraulic oil is rapidly increased together with the warm-up of the engine 13 at a low temperature, and the oil temperature is lowered when the temperature is excessively high. Thus, the temperature change of the hydraulic oil can be suppressed.

[Brief description of the drawings]

FIG. 1 is a partial hydraulic circuit diagram of a tractor.

FIG. 2 is an overall side view of the tractor.

FIG. 3 is a side view of a transmission case showing an arrangement of hydraulic equipment.

FIG. 4 is a longitudinal sectional view of the bubble removing device.

FIG. 5 is a cross-sectional plan view of the bubble removing device.

FIG. 6A is a side view of a transmission case showing an arrangement of a hydraulic device when the air bubble removing device is provided on an engine side, and FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mission case (oil tank) 2 Hydraulic pump 3 Hydraulic cylinder 4 Air bubble removal device 5 Heater

Claims (1)

[Claims] 1. A power vehicle in which hydraulic oil in a hydraulic tank 1 is sucked and supplied to each hydraulic device 3 by a hydraulic pump 2, wherein a hydraulic fluid is supplied to an oil passage between the hydraulic tank 1 and the pump 2. Means for generating a vortex and collecting and discharging air bubbles in a suction portion of the vortex, and heating the oil to the upstream side of the oil passage flowing into the air bubble removal apparatus 4 or to the air bubble removal apparatus 4 itself. 5. A hydraulic circuit structure for a powered vehicle, comprising: