JPS6140599Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention stores lubricating oil in a transmission case housing a gear transmission mechanism, supplies the lubricating oil as hydraulic oil to a hydraulic continuously variable transmission and a hydraulic cylinder, and The present invention relates to a hydraulic oil extraction structure in which a first strainer for hydraulic oil to be supplied to a hydraulic continuously variable transmission and a second strainer for hydraulic oil to be supplied to a hydraulic cylinder are installed in the transmission case.

When extracting gear lubricating oil as hydraulic oil, the extraction position must be reliably below the oil level even if the oil level fluctuates greatly due to aircraft vibration. In order to prevent the suction of air bubbles as much as possible, the oil outlet location is generally located near the bottom of the mission case. However,
Gear wear particles tend to settle near the bottom of the case, so it is necessary to install a strainer with sufficient filtration function at this oil extraction point, which requires an expensive strainer that is large and has a fine mesh and can withstand suction pressure. In addition to this, there was a drawback that the vertical height of the transmission case was increased.

As an example of the above-mentioned hydraulic oil extraction structure for the tractor, as described in Japanese Utility Model Application No. 52-85230, even when hydraulic oil is supplied separately to two hydraulic circuits, the strainer The structure was such that each was attached separately near the bottom of the transmission case, and this did not solve the disadvantages of requiring an expensive strainer and increasing the vertical height of the transmission case. .

In view of the above-mentioned circumstances, the present invention provides a hydraulic oil extraction structure in which the strainers for the two hydraulic circuits are installed separately near the bottom of the transmission case.
In order to avoid the inflow of gear wear particles as much as possible and at the same time prevent the suction of air bubbles, a recess is formed in the side wall near the bottom of the transmission case, and two strainers are installed inside this recess. ,
While adopting a structure that can reduce the vertical height of the transmission case, we focused on the fact that the hydraulic oil that passes through the two strainers has different uses, and devised the mounting arrangement of these strainers in the recess. It is an object of the present invention to provide a strainer that can be obtained at a relatively low cost and that can be housed compactly while reducing the size of a recessed portion without impairing the filtration function of the strainer.

A characteristic configuration of the present invention for achieving the above object is that, in the above-mentioned hydraulic oil extraction structure for a tractor, a recessed portion for accommodating both strainers is formed in a side wall portion near the bottom of the transmission case; The first strainer is installed near the entrance of the recessed part, and the second strainer is installed deeper than the first strainer, and the mesh of the second strainer is set to be coarser than the mesh of the first strainer. This configuration provides the following effects.

In other words, although the strainer is compactly installed near the entrance of the recess and further back, it is possible to downsize the recess without impairing the strainer's filtration function. 2. An inexpensive strainer can be used as the strainer.

In other words, if the first strainer is installed near the entrance of the recessed part and the second strainer is installed further back, the flow of hydraulic oil into the second strainer will be limited to the first strainer.
The suction resistance of the second strainer increases due to the obstruction caused by the strainer, and as a result, the diameter of the second strainer is increased to ensure a suction area and a sufficiently wide interval between the second strainer and the peripheral wall of the recessed portion. This not only increases the size of the recessed part, but also increases the size of the second
The strainer itself is expensive, but according to the present invention, the first strainer efficiently supplies hydraulic oil that has been filtered with sufficient precision to the hydraulic continuously variable transmission that is constantly driven while driving, with little suction resistance. The suction action of this first strainer suppresses the inflow of gear wear powder etc. to the depths of the recessed part.
A strainer with a coarser mesh than the strainer and smaller in size for a given suction amount can be used.

Therefore, it is possible to secure a wide distance between the peripheral wall of the recessed part and the second strainer, and it has become possible to downsize the recessed part without impairing the filtering function.

Furthermore, it has become possible to use a small, coarsely meshed and inexpensive strainer as the second strainer.

Next, embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a schematic side view of an agricultural tractor, in which the body is constructed by directly connecting an engine 1, a transmission housing 3 equipped with a main clutch 2, and a transmission case 4, and a front frame 5 extending from the engine 1.
The steering drive front wheels 6 are also mounted on the transmission case 4.
are each equipped with a driving rear wheel 7.

This tractor is driven hydraulically, and as shown in Fig. 2, a hydraulic continuously variable transmission (HTS) 8 capable of forward and reverse rotation is connected to the front of the transmission case 4. An input shaft 9 protruding forward at the top of the transmission 8 is connected to the main clutch 2.
The output shaft 11, which is connected to a main shaft 10 extending rearward from the transmission device 8 and which protrudes rearward at the lower part of the transmission 8, is gear-coupled with a first transmission shaft 12. 2 transmission shaft 13
The second transmission shaft 13 is connected to the final transmission shaft 14 by a gear, and the second transmission shaft 13 is connected to the final transmission shaft 14 to provide an auxiliary transmission mechanism 1 that performs a two-speed gear change.
5, and this final transmission shaft 14 is interlocked with a differential transmission 16 of the rear wheels 7 by a bevel gear. In addition, the input shaft 9 of the transmission 8 extends rearward as it is, and its rear extending end 9a connects to the PTO system first transmission shaft provided below the first transmission shaft 12 as an idling gear support shaft. 17 through a transmission mechanism 18 that performs two-stage gear change, and furthermore, this first transmission shaft 17 is connected through a one-way clutch 19.
It is interlocked and connected to a PTO system second transmission shaft 20, and is finally connected by a gear to a PTO 21 protruding from the rear end of the transmission case 4.

In addition, the lower part of the mission case 4 has the above-mentioned
An intermediate power extraction case 23 is attached which receives power from the shift gear 22 of the PTO transmission mechanism 18.
This is equipped with an intermediate PTO shaft 24. or,
A lift arm 26 driven by a single-acting hydraulic cylinder 25 is installed at the upper part of the transmission case 4.

Note that 27 in the figure is a front wheel transmission shaft that is gear-linked to the final transmission shaft 14, and extends forward through eight circles of the transmission.

The hydraulic continuously variable transmission 8 and the hydraulic cylinder 2
5 are both driven using lubricating oil stored in the transmission case 4 as hydraulic oil, and FIG. 3 shows the overall hydraulic system diagram, and FIG. 4 shows the hydraulic circuit of the transmission 8 .

The oil stored in the transmission case 4 is taken out into two systems via two strainers 30 and 31, and the oil in one system is sucked into the transmission 8 by an internal charge pump 23, and then passed through a replaceable cartridge-type filter. After finally removing dust at step 33, it is supplied to a charge circuit. All drained oil from the transmission 8 is connected to the suction port of a gear pump 36 directly connected to the engine 1 via an oil cooler 35 provided in front of a radiator 34 at the front of the machine body.

Also, the oil in the other system is directly supplied to the gear pump 3.
It is connected to the suction port of gear pump 3.
The oil discharged from the hydraulic cylinder 6 is supplied to a control valve 37 of the hydraulic cylinder 25. Incidentally, this valve 37 is directly connected to the upper surface of the mission case 4, so that the drained oil from the valve 37 is directly returned into the mission case 4.

In the present invention, the oil extraction sections of the two systems are configured as follows.

That is, a recessed portion 38 that opens forward is formed in a series on the left and right near the lower end of the intermediate wall in the transmission case 4, and the cylindrical first strainer 30 of the transmission 8 drive system is installed at the entrance of the recessed portion 38. In addition to protruding from the left side wall, a cylindrical second strainer 31 of the lift arm 26 drive system is installed protruding from the right side wall at the inner part of the recessed portion 38. And the first one on the entrance side
The strainer 30 has a fine mesh and is small. In other words, there is inevitably a large amount of gear wear powder on the inlet side of the recessed part 38, whereas in the inner part, gear wear powder is inherently less likely to flow in and is absorbed to some extent by the first strainer 30 on the inlet side. Therefore, the inflow is further reduced, and the second strainer 31 at the back has a coarser mesh than the first strainer 30 on the inlet side and functions sufficiently.

Note that the filter 33 needs to be replaced in a timely manner as the clogging progresses, and a differential pressure gauge 39 is installed to detect and display the pressure difference across the filter 33 in order to indicate when it is time to replace it. As shown in FIG. 6, this gauge 39 has an indicator strainer 41 slidably inserted into a transparent tube 40 that is connected to the primary and secondary oil passages of the filter 33. A coil spring 42 is installed on the secondary side of the filter 33 to press and bias the spool 41 toward the primary side, and a stopper 44 having an orifice 43 is installed on the primary side of the transparent tube 40. As the pressure difference between the spool 41 and the secondary side increases, the displacement of the spool 41 against the spring 42 can be visually recognized from the outside through a see-through window 45 having color-coded indicators. Incidentally, this gauge 39 is designed to be visible through an opening 46 on the side of the housing 3, as shown in FIG.

[Brief explanation of the drawing]

The drawings show an embodiment of the hydraulic oil extraction structure for a tractor according to the present invention. Fig. 1 is a side view of an agricultural tractor, Fig. 2 is a side view of the internal structure of the transmission case, and Fig. 3 shows the entire hydraulic system. Schematic diagram shown, 4th
The figure is a schematic diagram of the hydraulic circuit of the hydraulic continuously variable transmission, Figure 5 is a cross-sectional plan view of the oil outlet, Figure 6 is a cross-sectional plan view of the differential pressure gauge, and Figure 7 is a front view of the hydraulic continuously variable transmission. It is. 4...Mission case, 8 ...Hydraulic continuously variable transmission, 26...Lift arm, 25...Hydraulic cylinder, 30...First strainer, 31...Second
Strainer, 38... recessed part.

Claims (1)

[Scope of claim for utility model registration] Mission case 4 with internal gear transmission mechanism
A first strainer 30 stores lubricating oil therein and supplies the lubricating oil as hydraulic oil to the hydraulic continuously variable transmission 8 and the hydraulic cylinder 25, and a first strainer 30 for the hydraulic oil supplied to the hydraulic continuously variable transmission 8. The second strainer 31 for the hydraulic oil supplied to the hydraulic cylinder 25 is connected to the transmission case 4.
In the hydraulic oil extraction structure installed inside,
A recessed portion 38 for housing the strainers 30 and 31 is formed in a side wall portion near the bottom of the mission case 4, and the first strainer 30 is installed near the entrance of the recessed portion 38, and the first strainer 30 is installed near the entrance of the recessed portion 38. A hydraulic oil extraction structure for a tractor, characterized in that the second strainer 31 is installed deeper than the strainer 30, and the mesh of the second strainer 31 is set coarser than the mesh of the first strainer 30. The hydraulic oil extraction structure according to claim 1, wherein the hydraulic cylinder 25 is used to drive a lift arm 26.