JPS5811617Y2 - agricultural tractor - Google Patents

Description

[Detailed description of the invention] This invention is aimed at agricultural tractors that perform various tasks in the field, more specifically, agricultural tractors that are equipped with a hydraulic transmission device consisting of a combination of a positive displacement hydraulic pump and a hydraulic motor. , it is related to.

As is well known, a hydraulic power transmission system is equipped with a charge pump for replenishing the closed circuit between the hydraulic pump and the hydraulic motor, and the oil flows from the oil tank through the charge pump to the closed circuit in the hydraulic power transmission system. There are generally two types of filters in the oil supply circuit.

That is, this will be explained with reference to the circuit diagram of the hydraulic transmission device shown in FIG. 3. In the same figure, 8 is a variable displacement hydraulic pump, 9 is a constant displacement hydraulic motor, and 61 is the hydraulic pump 8 and the hydraulic motor. 9, the oil supply circuit supplies hydraulic oil from the oil tank T to the closed circuit 61 by the charge pump 12 driven by the engine 1 together with the hydraulic pump 8. An oil strainer 18 is inserted into the oil passage 62 connecting the charge pump 12 and the charge pump 12 to clean the oil sucked into the charge pump 12 and protect the charge pump. An oil strainer 13, which is a line filter inserted into the oil path 63 connecting the circuit 61 to clean the oil supplied to the closed path 61 and protect the hydraulic pump 8 and the hydraulic motor 9, is provided. The oil strainer 18 has a relatively coarse mesh so as not to create resistance to oil suction by the charge pump 12, and the oil strainer 13 has a fine mesh because it protects the main parts 8 and 9 of the device. considered as something to behold.

In FIG. 3, 64 is a pressure regulating valve that sets the oil pressure of hydraulic oil supplied to the closed circuit 61, 65 is a flow control valve that controls the flow rate of hydraulic oil supplied to the closed circuit 61, and 66 is a closed circuit 61. 01 pair of check valves to prevent backflow of oil from the charge pump 12 direction, 61 is a pressure regulating valve that sets the oil pressure of the pump 8 discharge side circuit in the closed circuit 61, and 68 is a closed circuit from the pressure regulating valve 67 side. 61 is a pair of check valves for preventing oil from flowing back into the pump 8 suction side circuit.

By the way, when this type of hydraulic transmission device is to be adopted in an agricultural tractor, it is important to know how to arrange the oil strainer 18 and oil strainer 13 in relation to the oil tank 7, closed circuit 61, and charge pump 12. , becomes a problem.

First of all, in agricultural tractors, the transmission case is often used as an oil tank for various hydraulic equipment, and an oil strainer is installed in the lower part of the transmission case, that is, in a position where it is immersed in oil. This is a common practice, and there is no problem as long as the oil strainer 18 as described above is installed in the lower part of the transmission case, but the oil strainer 1 that constitutes the line filter as described above
There are restrictions on installing up to 3 in the mission case.

Specifically, when the oil strainer 18 is installed as described above, an outer wall or casing for the kernel oil strainer is not required, whereas the oil strainer 13 is installed in the transmission case below the oil level. Whether it is installed above the oil level or above the oil level, an outer wall or casing is required, but since the trans □ tension mechanism including the hydraulic transmission device is installed inside the transmission case, there is plenty of space. Since it has almost no space and is equipped with fine holes as mentioned above, it is necessary to install the casing for the oil strainer 13, which is a filter with a large area and is large in size, inside the mission case. It is difficult to install the transmission case in a fixed manner, and if a space for such a casing is forcibly formed within the transmission case, the transmission case will become larger.

What can be considered is, for example,
As disclosed in Publication No. 4, the oil strainer 18 and oil strainer 13 shown in FIG. However, when doing this, the single filter eye described above should be installed in the oil strainer 13.
As the oil suction resistance of the charge pump increases significantly, air enters from the joint between the oil suction pipe and the charge pump, causing cavitation phenomenon, which increases pump noise. This may cause an increase in the amount of water or a decrease in the life of the pump.

Next, since hydraulic oil is supplied from the charge pump 12 to the closed circuit 61 via the oil strainer 13, these three
2, 13, and 61 are preferably arranged as close as possible to simplify the oil piping structure.

As in the above-mentioned Utility Model Application Publication No. 52-70824, the installation part for a single filter that serves both the oil strainer 18 and the oil strainer 13 shown in FIG. If this is required, the distance between such a single filter and the charge pump becomes large, which complicates the oil piping structure and increases the number of oil piping outside the aircraft body, which is undesirable.

Of course, it is preferable that the distance between the oil tank 7 and the charge pump 12 shown in FIG. This type of latch housing is formed inside the clutch housing of a tractor.Since the bottom of the latch housing is located at a considerably higher level than the bottom of the transmission case, the suction end of the oil suction pipe can easily fall above the oil level due to vibrations of the machine. exposure to, causing cavitation.

The object of this invention is to provide a conventional agricultural tractor that solves the above-mentioned problems associated with a hydraulic oil supply mechanism for a hydraulic transmission device.

Regarding the illustrated embodiment, the configuration of the agricultural tractor according to the invention will be explained. As shown in FIG. Conducted to the rear through the housing,
It is configured to rotate the left and right rear wheels 2 to cause the machine to travel, and to rotationally drive a PTO shaft 3 that drives a working machine (not shown) connected to the rear of the machine.

In addition, in the case shown in the figure, a mechanism is provided to selectively transmit power from the traveling power transmission unit to the left and right front wheels 4 as described later. It is designed so that it can be driven.

The body housing of the illustrated agricultural tractor includes a clutch housing 5 that is located behind the engine 1 and houses the main clutch 6 inside the large diameter portion 5a at the front end, and a transmission case 1 that is located behind the clutch housing 5. ing.

In the illustrated case, the mission case 7 is divided into two parts, the front case part 7A and the rear case part IB, but as shown in FIG. type hydraulic pump 8 and constant displacement type hydraulic motor 9
A hydraulic power transmission device 10 is provided, which is a hydraulic power transmission device 10 consisting of a combination of the following, and which constitutes a traveling power main transmission device.

In particular, an oil passage forming plate 11 is provided between the clutch housing 5 and the front case portion 7A of the transmission case 7, and the above-mentioned hydraulic pump 8 and hydraulic motor 9 are arranged in the illustrated case. It is mounted on the back surface of this oil passage forming plate 11 and provided inside the front case portion IA.

An oil passage (not shown) that constitutes a closed circuit between the hydraulic pump 8 and the hydraulic motor 9 is formed in the oil passage forming plate 11. A charge pump 12 is mounted on the front surface of the road forming plate 11 concentrically with the hydraulic pump 8 to supply hydraulic oil to the closed circuit between the hydraulic pump 8 and the hydraulic motor 9. It is provided within the clutch housing 5.

The oil strainer 13 inserted into the hydraulic oil supply circuit between the charge pump 12 and the closed circuit is also inserted into the housing 5 from the side wall opening of the clutch housing 5, and is inserted into the housing 5 from the front part of the oil passage forming plate 11. It is located inside Klutchino Ujifugu 5.

An oil passage between the charge pump 12 and the oil strainer 13 and an oil passage (hereinafter not shown) between the oil strainer 13 and the closed circuit are also formed in the oil passage forming plate 11.

Note that necessary relief valves and check valves in the hydraulic transmission device 10 are appropriately incorporated into the oil passage forming plate 11 and the valve case 14 installed on the plate 11.

Further, the change control of the gear ratio by the hydraulic transmission device 10, that is, the change adjustment of the swash plate angle of the variable displacement hydraulic pump 8 is performed by the main gear shift lever 15.
and a servo control W between the hydraulic pump 8 (not shown)
is provided in the servomechanism housing 16 installed on the upper surface of the tension case 7.

Furthermore, the oil tank for the hydraulic conduction device 10 and the hydraulic lift device 11 (Fig. 1) on the upper surface of the rear part of the fuselage is also used as the mission case T, and an oil strainer 18 is installed in the lower part of the rear case part IB. It is installed.

A drain hole and a window hole for adjusting the lever are formed in the side wall of the clutch housing 5 and the side wall of the front case portion 7A, and this window hole is releasably closed by a lid 19, 20 shown in FIG. .

As shown in FIG. 2, a mechanical transmission 21 is provided at the rear of the hydraulic conduction device 10 and is disposed at a front power position within the rear case portion 7B, constituting a traveling power sub-transmission.

This mechanical transmission 21 includes a supporting wall portion 22 that is integral with the front case portion 7A and a supporting wall portion 23 that is integral with the rear case portion 7B.
The front end is inserted into and supported by the transmission shaft 24, which is provided with both ends supported by the transmission shaft 24, and the splinter cylinder 26 fitted to the output end of the motor shaft 25 of the hydraulic motor 9, and the rear end is supported by the support wall. A transmission shaft 27 supported by the body 23 is provided, and a transmission shaft 2γ is provided concentrically with the motor shaft 25.

Then, the small diameter gear 28 provided on the spline cylinder 26 by spline fitting is meshed with the large diameter gear 29 on the transmission shaft 24, and the transmission shaft 24 is connected to the motor shaft 25 in a deceleration interlocking manner. Two transmission gears 30 and 31 having different diameters are provided on the transmission shaft 27, and an idler gear 32 meshed with the transmission gear 30 and having internal teeth 32a is provided on the transmission shaft 27. The rotating gear 32, the internal teeth 32a, and the speed change gear 31
A pawl 33a that can be selectively engaged with the pawl 26a at the end of the spline cylinder 26 and a shift gear 33 that can be selectively engaged with the pawl 26a at the end of the spline cylinder 26.
A shift gear 33 formed with a
The meshing of the gear 33 with the internal teeth 32a (by the coupling of the idle gear 32 to the transmission shaft 27 changes the gear ratio of 1st speed,
The gear ratio of 2nd speed is controlled by the engagement between gears 31 and 33.
The coupling between the shafts 25 and 27 through meshing between the shafts 6a and 33a allows three speed change ratios to be selectively obtained.

A transmission shaft 27 constituting an output shaft of the transmission section 10.21 is connected to the left and right rear wheels via a bevel gear 27a integrally formed at its rear end.

Similarly, as shown in FIG. 2, an intermediate section 34 for power extraction is provided below the transmission shaft 21 and supported by the rear case section 7B, and is attached to the opening of the mission case I below the intermediate shaft 34. Mission case 7 below 34
A power take-off shaft 36 is provided on the intermediate shaft 34 and supported by a housing 35 attached to the opening, and always maintains meshing with the gear 33 no matter which shift gear position the shift gear 33 is displaced to. A wide intermediate gear 37 is provided on the power take-off shaft 36, and a shift gear 38 that can selectively mesh with the intermediate gear 31 is provided on the power take-off shaft 36, and the power take-off shaft 36 is selectively interlocked with the transmission shaft 21. Therefore, the power take-off shaft 36 is connected to a transmission shaft 40 connected to the front wheels 4 through a coupling 39, so that the front wheels 4 can be selectively driven as described above. .

Further, as shown in FIG. 2, the pump shaft 41 of the hydraulic pump 8 is connected by a coupling 43 to a transmission shaft 42 that transmits power in the axial direction of the PTO shaft 3.

The pump shaft 41 of the hydraulic pump 8 and the pump shaft 44 of the charge pump 12 are connected within the oil passage forming plate 11, and the pump shaft 44 of the charge pump 12 is connected to the engine 1 via the main clutch 6. It is connected within the clutch housing 5 by a coupling 46 to a drive shaft 45 that is interlocked.

In FIG. 1, reference numeral 41 denotes an auxiliary transmission lever, which operates to displace the shift gear 33 of the mechanical transmission 21, and 48 denotes a front wheel drive on/off lever, which operates to displace the shift gear 38. is the PTO gear lever,
A hydraulic lift lever 51 for the hydraulic lift device 11 controls the main clutch 6. Clutch pedal for disengaging operation, 52 is a passenger seat.

As is clear from the above description, the agricultural tractor of this invention includes a clutch housing 2 in which the main clutch 6 is housed in the front end 5a, and a transmission case 7 which houses the hydraulic transmission device 10 and is also used as an oil tank. An oil passage forming plate 11, which forms a closed circuit between the hydraulic pump 8 and the hydraulic motor 9 in the hydraulic transmission device 10, is sandwiched between the hydraulic transmission device 10 and a charge pump 12 for replenishing the closed circuit with hydraulic oil. is attached to the front surface of the oil passage forming plate 11 and installed in the clutch housing 5, and an oil strainer 18 inserted into the oil passage connecting the oil tank and the charge pump 12 is installed in the lower part of the transmission case part. In addition, the oil strainer 13 inserted into the oil passage connecting the charge pump 12 and the closed circuit described above is installed at appropriate positions in the clutch housing 5. It has advantages such as.

That is, regarding the hydraulic oil supply mechanism for the hydraulic transmission device 10, first of all, in terms of installation space, since the oil strainer 18 is installed at the lower part of the transmission case 7, which is an oil tank, the oil strainer 18 is covered with an outer wall or a casing. Of course, it is not necessary and it becomes small and does not pose a problem in terms of installation space, but the charge pump 12 and the charge pump 12 are installed inside the clutch housing 5, which has a large free space at the rear end by simply housing the main clutch at the front end. Since the oil strainer 13 is made of particularly fine mesh, it has a large surface area and requires an outer wall or casing to cover it, making it large in size.
Since the agricultural tractor of this invention has a configuration in which the hydraulic oil supply mechanism for the hydraulic transmission device 10 is installed, the components of the hydraulic oil supply mechanism for the hydraulic transmission device 10 may increase the size of the mission case 7 or damage the operator's suspension on the outer surface of the machine body. It has been installed without causing any problems such as

Next, regarding the problem of cavitation, which can lead to increased pump noise and reduced pump life, the mission case 7 is also used as an oil tank for the hydraulic transmission device 10, and an oil strainer is installed at the bottom of the mission case 7. 18
Since the oil strainer 18 is installed, air is not sucked in the oil strainer 18, and since the oil strainer 18 and the oil strainer 12, which are line filters, are constructed separately, the oil strainer 18 18, the mesh is relatively coarse, and the oil suction resistance of the charge pump 12 is kept low, and the charge pump 12 is connected to the suction pipe joint 0.
This eliminates the possibility of air being sucked in from the outside, thereby preventing cavitation and other problems.

In particular, on the oil piping, the charge pump 12 and the oil strainer 13 are arranged inside the clutch housing 5, and the closed circuit between the hydraulic pump 8 and the hydraulic motor 9 in the hydraulic transmission device 10 is located behind the clutch housing 5. Since the oil passage forming plate 11 is located at the end, the oil piping between the charge pump 12 and the oil strainer 13 and the oil piping between the oil strainer 13 and the closed circuit are
It can be extremely short and can be installed inside the clutch housing 5, and a part of the oil piping between the oil strainer 18 at the lower part of the tension case I and the charge pump 12 on the oil passage forming plate 11 can be formed by forming an oil passage. This can be omitted by forming a suction oil passage leading to the charge pump 12 on the plate 11, and as a result, the present agricultural tractor has an extremely simple oil piping structure for the hydraulic oil replenishment mechanism for the hydraulic transmission device 10. Along with this, it has become possible to install it inside the tractor body as much as possible.

As described above, the agricultural tractor of this invention solves the problems of the installation space of the hydraulic oil replenishment mechanism, cavitation, and oil piping structure in the conventional tractor as explained at the beginning. There is.

[Brief explanation of the drawing]

FIG. 1 is a side view of an embodiment of this invention, FIG. 2 is a vertical sectional side view of the main parts of the same embodiment, and FIG. 3 is a hydraulic circuit diagram showing a hydraulic power transmission device. 5...Clutch housing, 5a...
Front end large diameter part of clutch housing 5, 6...Main clutch, 7...Mission case, 8...
...Hydraulic pump, 9...Hydraulic motor, 10.
... Hydraulic transmission device, 11 ... Oil path forming plate, 12 ... Charge pump, 13 ...
Oil strainer.

Claims (1)

[Scope of utility model registration request] A clutch housing that can accommodate the main clutch at the front end,
An oil passage forming plate, which forms an oil passage forming a closed circuit between the hydraulic pump and the hydraulic motor in the hydraulic transmission system, is sandwiched between the transmission case, which houses the hydraulic transmission system and also serves as an oil tank. A charge pump for supplying hydraulic oil to the closed circuit is mounted on the front of the oil passage forming plate and installed inside the clutch housing, and an oil passage connecting the oil tank and the charge pump is installed. The oil strainer inserted into the clutch housing was installed at the lower part of the transmission case, and the oil strainer inserted into the oil passage connecting the charge pump and the closed circuit described above was installed at the appropriate location inside the clutch housing. , Agricultural tractor with special features.