JPH0430408Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an air balance device for a hydraulic system for operating a lifter for raising and lowering a ground-based working machine, etc. in a tractor, for example.

[Prior art]

Generally, in an oil tank and a hydraulic cylinder of a hydraulic system, as the hydraulic oil moves, air moves (breathing action) from the upper space on the oil tank side to the air chamber on the hydraulic cylinder side. That is, when a predetermined amount of oil is caused to flow into the hydraulic cylinder side from the oil tank via the pump, the volume of the air chamber on the hydraulic cylinder side decreases, and with this decrease, the air in the air chamber is discharged outside the cylinder. On the other hand, on the oil tank side, as oil is supplied to the hydraulic cylinder side, the amount of oil decreases, so the volume of the upper space of the tank increases, and air flows into this space. Furthermore, the movement of air between the oil tank and the hydraulic cylinder described above also occurs in the opposite manner when a predetermined amount of oil is returned from the hydraulic cylinder to the oil tank.

By the way, in the conventional hydraulic system for operating a lifter that raises and lowers ground work equipment such as a tractor, the above-mentioned air balance is achieved by separately installing a breather in each of the oil tank and the air chamber of the hydraulic cylinder. is the reality.

[Problem that the invention attempts to solve]

As mentioned above, the means of air balance in conventional hydraulic systems is to provide separate breathers for the oil tank and hydraulic cylinder, so the movement of air (inflow and outflow) in the oil tank and hydraulic cylinder is controlled. Therefore, there is no mutual supplementary effect between the two. Therefore, with conventional air balance means, there is a large loss in air flow, resulting in poor response of the lift arm of the elevator, and moreover, dust and the like can flow into the oil tank or hydraulic cylinder through the breather, causing problems between both. Damage accelerates.

[Means for solving problems and their effects]

An oil tank, a hydraulic cylinder that operates when a predetermined amount of oil is pressurized from the oil tank via an oil pump, and a breather pipe that communicates an air chamber of the hydraulic cylinder with an upper part of the oil tank. By providing this, the air balance between the oil tank and the hydraulic cylinder can be mutually complemented, and the internal pressure of the air chamber of the hydraulic cylinder and the internal pressure of the oil tank can be made constant, and the oil can be prevented from flowing into the hydraulic cylinder. By improving the oil flow and eliminating dust from entering the oil, the durability of the hydraulic cylinder and the entire hydraulic system as well as the functionality of the entire hydraulic system are improved.

〔Example〕

First, with reference to FIG. 1, an outline of a riding vehicle (tractor) employing an oil tank mounting structure according to the present invention will be explained.

The drawing is a partially cutaway side view of the riding vehicle 1, in which an engine is mounted on the front part of the vehicle body 2 of the riding vehicle 1, and a transmission case is arranged at the rear of the vehicle body 2. There is. The crankshaft of the engine and the transmission input shaft of the transmission case are connected substantially in a straight line via a propulsion shaft. A passenger seat 3 is provided on the rear portion of the vehicle body 2, and front wheels 4 and rear wheels 5 of the same diameter are provided on the front, rear, left and right sides of the vehicle body 2. Further, this riding work vehicle 1 can steer the front and rear wheels 4 and 5 by operating the handle 6, and is capable of four-wheel drive.

Further, swinging arms 7 are pivotally attached to the front and rear of the vehicle body 2 so as to be able to swing up and down, and various working machines (not shown in the figure) can be attached to the tips of the swinging arms 7. It's summery. Further, one end of a link member 9 of a link device 8 is pivotally attached to the swing arm 7. The other ink member 9 of the link device 8 is pivotally connected to the hydraulic cylinder 10, and each of these link members 9 swings up and down due to the movement of the piston 10a in the hydraulic cylinder 10, and this swing causes the link The swing arm 7 swings via the member 9 to raise and lower the working machine. Further, the passenger seat 3 in front of the rear hydraulic cylinder 10
An oil tank 11 is installed below the oil tank 11, and an appropriate amount of hydraulic oil is supplied to the oil pump 12.
The discharge oil is selectively supplied to both the front and rear hydraulic cylinders 10, 10 through the control valve 13.

FIG. 2 shows both front and rear hydraulic cylinders 10, 1 mounted on the front and rear of the riding vehicle (tractor) 1.
1 is a schematic configuration explanatory diagram of an air balance device of a hydraulic system when predetermined oil is supplied from one oil tank 11 disposed below the passenger seat 3 via an oil pump 12 and a control valve 13. .

An oil tank 11 is arranged between the front and rear hydraulic cylinders 10, 10, and the lower part of the oil tank 11 is communicated with the oil fill hole 14 of the two hydraulic cylinders 10, 10 through an oil pump 12 and a control valve 13. ing. On the other hand, the upper space 15 of the oil tank 11 is communicated with the air chambers 17 of the two hydraulic cylinders 10, 10 via a breather pipe 16.

3 and 4 show a breather pipe 1 between the rear hydraulic cylinder 10 and the oil tank 11.
FIG. 6 is a specific configuration explanatory diagram of No. 6;

FIG. 3 is an explanatory view of the configuration seen from above with the passenger seat 3 removed.

The oil tank 11 is provided approximately vertically below the passenger seat 3, and the outlet of the breather pipe 16 faces the side. Hydraulic cylinder 10 air chamber 1 branched from the breather pipe 16 and provided at the rear
It is connected to 7. An oil discharge hole 18 provided below the oil tank 11 is communicated with the oil pump 12 via a pipe, and an oil inlet/outlet hole 19 of the control valve 13 is connected to the oil fill hole 14 of the hydraulic cylinder 10 via a pipe. It is communicated with.

Figure 4 shows the oil tank 1 explained in Figure 3 above.
1 and a hydraulic cylinder 10 as viewed from the side. FIG.

The operation of the above embodiment will be explained below.

That is, when one hydraulic cylinder 10 is supplied with an appropriate amount of oil from the oil tank 11 and the hydraulic cylinder 10 is operated (at this time, the other hydraulic cylinder 10 is in an inoperative state),
The hydraulic cylinder 10, which has been supplied with an appropriate amount of oil from the oil tank 11, starts a predetermined operation.
At this time, the volume of the upper space 15 of the oil tank 11 increases as the amount of oil supplied to the hydraulic cylinder 10 decreases. At this time, in the sealed space formed by the oil tank 11 and the hydraulic cylinder connected by the breather pipe 16, the total volume of the oil tank 11 and the hydraulic cylinder 10 is constant, so the volume increases. The volume of the upper space 15 of the oil tank 11 that has been increased is equal to the decrease in the volume of the air chamber 17 of the hydraulic cylinder 10, and the air from the air chamber 17 is transferred to the upper space 15 of the oil tank 11 whose volume has increased.
It will be press-fitted into the On the other hand, when oil is returned to the oil tank 11, the volume of the air chamber 17 of the hydraulic cylinder 10 increases by the amount of returned oil, and this increased volume of the hydraulic cylinder 10 becomes the upper space of the oil tank 11. 15, the air from the upper space 15 is forced into the air chamber 17 of the hydraulic cylinder 10 whose volume has increased, and the air is complemented by the inflow and outflow of oil. The internal pressures of the oil tank 11 and hydraulic cylinder 10 are maintained constant.

In conventional oil tanks, the air around the oil tank directly flows in through a breather pipe installed independently in the oil tank, which has caused various problems as mentioned in the introduction, but with the present invention, Since the configuration is as described above, the oil tank 1 is provided in the upper space 15 of the oil tank 11.
The air present in the air chamber 17 of the hydraulic cylinder 10 on the side to be supplied with oil from the hydraulic cylinder 1 is caused to flow into each other via the breather pipe 16 provided in communication with the air chamber 17.

Therefore, the upper space 1 of the oil tank 11
5 and the air chamber 17 of the hydraulic cylinder 10 exists in the upper space 15 of the oil tank 11 and the air chamber 17 of the hydraulic cylinder 10. There will be no chance of contamination.

Therefore, the upper space 15 of the oil tank 11 and the air chamber 17 of the hydraulic cylinder 10 are not contaminated with dust or the like that would contaminate the oil, and the oil is clean and the hydraulic cylinder 10 remains clean even during long-term use. Demonstrates excellent effects without causing any damage.

Moreover, the oil tank 11 and the hydraulic cylinder 10
The inflow and outflow of air between them, the so-called breathing action, corresponds to the pumping action when oil is supplied from the oil tank 11 to the hydraulic cylinder 10 and vice versa when oil is returned from the hydraulic cylinder 10 to the oil tank 11. They function as mutually complementary functions, so that the pressure feeding action and pressure feeding control of the oil pump 12 and the control valve 13 can be performed extremely smoothly, and oil feeding can be carried out without strain.

[Effect of idea]

The present invention provides a breather pipe that communicates between the upper space of an oil tank and the air chamber of a hydraulic cylinder into which a predetermined amount of oil is pressurized from the oil tank via an oil pump and a control valve. Since the air flow in and out between the upper space of the oil tank and the air chamber of the hydraulic cylinder is complemented during operation, the hydraulic pressure of the hydraulic cylinder can be adjusted very smoothly, and the responsiveness of the linkage device is improved. gets better.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an embodiment of a passenger work vehicle equipped with an air balance device for a hydraulic system according to the present invention, FIG. FIG. 4 is a diagram illustrating a specific configuration of an air balance device of the same hydraulic system. 10... Hydraulic cylinder, 11... Oil tank, 12... Oil pump, 13... Control valve, 15... Upper space, 16... Breather pipe, 17... Air chamber.

Claims (1)

[Scope of utility model registration request] An oil tank, a hydraulic cylinder operated by pressurizing a predetermined oil from the oil tank via an oil pump and a control valve, and an air chamber of the hydraulic cylinder communicating with an upper space of the oil tank. An air balance device for a hydraulic system, comprising a breather pipe.