JPH021565Y2 - - Google Patents

Description

[Detailed explanation of the idea] (b) Industrial application fields The present invention relates to a hydraulic system for a tractor.

(b) Prior Art Conventionally, in tractors in which the front and rear transmissions are connected by an intermediate transmission, a hydraulic pump sucks in oil from the rear transmission and pumps it out to the power steering box, and the return oil is returned to the rear transmission. Ta.

(c) Problems to be solved by the invention In the known tractor, the oil from the power steering was returned to the rear transmission, and the front transmission was filled with oil separately, so the oil in the front transmission became abnormally hot. It deteriorated quickly.

In addition, since the oil returned to the transmission later is sucked in again as hydraulic oil by the hydraulic pump, air bubbles get mixed into the hydraulic oil, causing noise and malfunctions in the operating system.

(d) Means for Solving Problems The present invention provides a hydraulic pump in which a front transmission and a rear transmission are connected by an intermediate transmission, and the suction port is connected to the rear transmission and the discharge port is connected to the power steering box. and a return oil passage whose one end is connected to the outlet of the power steering box and whose other end is connected to the front transmission, and an oil passage formed in the intermediate transmission to connect the front transmission and the rear transmission. By configuring it as follows, the hydraulic fluid from the power steering box is returned to the front transmission.
The oil in the front transmission is circulated through the intermediate transmission to the rear transmission to prevent the oil in the front transmission from becoming hot, and at the same time, the air bubbles generated during the return are extinguished while the oil passes through the intermediate transmission, resulting in hydraulic operation. The above-mentioned problem was solved by preventing air bubbles from being mixed into the oil.

(E) Function The hydraulic pump sucks hydraulic fluid from the rear transmission and pumps it to the power steering box, hydraulic lift case, etc., and the hydraulic fluid from the power steering box returns to the front transmission to lubricate its transmission mechanism. It then passes through an intermediate transmission, returns to the post-mission, and is then sucked into a hydraulic pump.

(F) Example An example of the present invention will be explained with reference to the drawings.
The front transmission 1 and the rear transmission 2 are connected by an intermediate transmission 3 as shown in FIGS. As shown in FIG. 2, the front axle 6 and power steering box 7 are installed, and they are attached to the pitman arm 8a.
The steering wheel 9 is connected to the power steering box 7 via a steering shaft 10, a bevel case 11, a rod 12 (see FIG. 3), and the like.

Inside the previous mission 1, as in the conventional one,
As shown in FIG. 1, a flywheel 14, a clutch 15, and a drive gear 1 are attached to a drive shaft 13.
6, input gear 18 meshing with it, front wheel drive shaft 1
7 gear 20, a front wheel drive shaft 21, and gears 22, 23 that transmit power thereto, and the rear transmission 2 is equipped with a pinion shaft 25 that drives the rear wheels, a counter gear 26, and a large number of transmission gears. The input gear 18 and the counter gear 26 are supported by holders 27 and 28 via bearings 30 and 31, respectively, and the cylindrical shaft 32 into which the front wheel drive shaft 17 is inserted is connected to the input gear by means of spline cylinders 33 and 34. It is connected to a gear 18 and a counter gear 26, and the rear end of the front wheel drive shaft 17 is connected to a pinion shaft 25 by a spline tube 35.

The cylindrical shaft 32 is eccentrically covered by a cylindrical body 36 which overlaps the lower surface of the top plate 3a of the intermediate mission 3 constituting the step and whose radius is larger than the distance between the top plate 3a and the axis of the front wheel drive shaft 21. The cylindrical body 36 is fixed to the walls of the front and rear transmissions 1 and 2 so that its lower part is approximately at the same height or slightly lower than the outer rings of the bearings 30 and 31. The transmissions 1 and 2 are the bearings 30 and 31.
It communicates with the cylindrical body 36 via between the outer ring and the inner ring.

Further, a hydraulic pump 3 attached to the engine 4
As shown in FIGS. 2 and 3, the suction port 7 is connected to the suction port 38 of the rear transmission 2 through a suction pipe 40 in which an oil filter 39 is interposed, and the pressure pipe 41 connected to the discharge port is connected to the suction port 38 of the rear engine 2. One side is connected to the power steering box 7 via a pressure pipe 43, and the return pipe 45 is connected to the front transmission 1, and the return pipe 45 from the relief valve 42a of the priority valve 42 is connected to the power steering box 7 through a pressure pipe 43. The pipe 46 joins the return pipe 45 at joint a and communicates with the pre-mission 1, and another pressure pipe 47 from the priority valve 42 connects to the control valve 4.
8 to the hydraulic lift case 50.

The above-mentioned hydraulic circuit will be explained with reference to FIG. 10. The hydraulic pump 37 sucks hydraulic fluid from the rear transmission 2 through the suction pipe 40, discharges it to the pressure pipe 41, and distributes it through the priority valve 42. On the one hand, hydraulic oil is sent to the power steering box 7 by a pressure pipe 43, the return oil flows into the front transmission 1 via a return pipe 45, and on the other hand, via a pressure pipe 47 and a control valve 48 to a hydraulic lift case 50. The returned oil is then returned to the transmission 2 through a pipe 51.

Furthermore, when high pressure is generated within the power steering box 7, the relief valve 42a is activated.
Hydraulic fluid passes through return pipe 46 to joint a.
It joins the return pipe 45 at the point where it is returned to the previous mission 1.

The hydraulic fluid returned to the front transmission 1 accumulates in the front transmission 1 to lubricate the transmission mechanism, and flows from the bearing 31 into the cylindrical body 36 of the intermediate transmission 3, and then flows into the bearing 3.
0 to post-mission 2.

At this time, the gear transmission part of the front transmission 1 has a small internal volume and the hydraulic oil tends to reach a high temperature, but since it is constantly circulated, it is possible to suppress the high temperature, and the return oil is transferred to the front transmission 1. When it flows into the cylinder 36, it foams, but it disappears while flowing inside the cylinder 36 and then returns to the mission 2.
Air bubbles are not mixed into the hydraulic fluid sucked out from the suction port 38.

Further, it is desirable that the diameter of the cylinder body 36 is as small as possible within the range that allows rotation of the cylinder shaft 32 and its joint, the spline cylinder 35, and that the top plate 3a, which serves as a step, is made low. If they are arranged concentrically as shown in FIG. 5, the end of the cylinder 36 closes the space between the inner ring and outer ring of the bearings 30, 31, which impairs the flow of hydraulic fluid. The cylinder body 36 has a diameter sufficiently larger than that of the spline cylinder 35, and only the upper part is placed close to the cylinder shaft 32 and the spline cylinder 35 so that the cylinder shaft 32
The bearings 30 and 31 are fitted into the holes in the walls of the front and rear transmissions 1 and 2 in a downwardly eccentric state and are welded to each other. There is communication between the front and back, allowing smooth flow of hydraulic oil.

Figures 7 to 9 show front mission 1 and rear mission 2.
This shows another example of the connection part of the intermediate transmission 3, which is similar to the above-mentioned embodiment in that the cylinder body 36 is made larger in diameter and eccentrically downward, and in this example, the holders 27 and 28 are Groove 5 on the inner peripheral surface of the lower part of
2, 52 are bored, and the hydraulic oil flows through the bearings 30, 31 and the grooves 52, 52, making the circulation even smoother.

(g) Effects of the invention The present invention provides a tractor in which the front transmission 1 and the rear transmission 2 are connected by the intermediate transmission 3 as described above, and in which the intake port is connected to the rear transmission 2.
A hydraulic pump 37 whose discharge port is connected to the power steering box 7, a return oil passage 45 whose one end is connected to the outlet of the power steering box 7 and the other end connected to the front transmission 1, and the front transmission 1. Since it has an oil passage formed in the intermediate transmission 3 to connect it with the rear transmission 2,
The return oil from power steering box 7 is returned to front transmission 1, and then it is transferred to intermediate transmission 3.
After the hydraulic pump sucks in the hydraulic oil, it flows to the transmission 2, which prevents the oil temperature in the front transmission 1, which tends to be high, from rising abnormally, and allows it to operate frequently. The return oil from the power steering is returned to the front transmission 1, and it is returned to the rear transmission 2, so that no air bubbles are generated, and the hydraulic pump 37 sucks air bubbles from the rear transmission 2, causing noise from the hydraulic system. It will not cause any malfunction or malfunction.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention,
Fig. 1 is a longitudinal cross-sectional view of the front transmission, intermediate transmission, and rear transmission; Fig. 2 is a side view showing the piping of the tractor; Fig. 3 is a plan view of the same; Fig. 4 is a cross-sectional view of the upper part of the intermediate transmission; FIG. 5 is a cross-sectional view of the same example as above, FIG. 6 is a vertical cross-sectional view of the intermediate transmission, FIG. 7 is a vertical cross-sectional view of the intermediate transmission in another embodiment, and FIG. 8 is a front view of the same transmission part. 9th
The figures are a sectional view taken along the line AA in FIG. 7, and FIG. 10 is a hydraulic circuit diagram. 1... Front mission, 2... Back mission, 3
...Intermediate transmission, 7...Power steering box, 30, 31...Bearing, 36...
Cylindrical body, 37...hydraulic pump, 45, 46...return pipe.

Claims (1)

[Scope of utility model registration request] In a tractor in which a front transmission 1 and a rear transmission 2 are connected by an intermediate transmission 3, a hydraulic pump 37 has a suction port connected to the rear transmission 2 and a discharge port connected to a power steering box 7;
A return oil passage 45 having one end connected to the outlet of the power steering box 7 and the other end connected to the front transmission 1 is formed in the intermediate transmission 3 to connect the front transmission 1 and the rear transmission 2. A hydraulic system for a tractor, characterized by having an oil passage.