JPS6128508Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is mainly used for agricultural purposes, in which the engine, main clutch chamber, and transmission case are arranged in front and back in series in this order, and a traveling gear transmission mechanism is installed inside the transmission case. This paper relates to the transmission structure of a tractor. In recent years, some agricultural tractors have incorporated a multi-disc hydraulic tractor clutch into the gear transmission mechanism in order to improve the speed change operability of the traveling system. In other words, hydraulic clutches are installed in multiple pairs of gears that are always in mesh, and by operating a control valve, only the hydraulic clutch of one gear pair is engaged and the other gear pairs are placed in an idle transmission state. This allows for easy gear changes without having to operate the main clutch each time the gear is changed, unlike a normal gear shift type. However, a transmission case that uses such a hydraulic clutch type transmission requires a major change in specifications from a gear shift type, resulting in an increase in costs. This invention enables the transmission case of a general gear shift type to be used as well, and while minimizing the cost increase due to the introduction of a hydraulic clutch, it also enables the desired transmission form to be obtained while providing lubrication and cooling for a multi-disc hydraulic clutch. The purpose is to ensure that the information is conveyed in a good manner. Embodiments of the present invention will be described below based on illustrative drawings. The figure shows the transmission structure of an agricultural tractor, in which an engine 1, a main clutch housing 2, and a transmission case 3 are connected in series in this order, and the engine output is appropriately shifted within the transmission case. Rear wheel drive shaft 4 protruding from both rear sides,
4 and a PTO shaft 5 protruding from the rear. The front part of the transmission case 3 is equipped with a main gear transmission mechanism 8 for the driving system that changes gears in four stages by selective shifting of shift gears 6 and 7, and the rear part of the case is equipped with shift gears 9a,
The vehicle is equipped with an auxiliary gear transmission mechanism 10 for the traveling system that performs two-speed transmission by the shift 9b, and a differential transmission mechanism 11 for the left and right rear wheel drive shafts 4,4. In addition, a shift gear 12 is located between the front and rear of the transmission case 3.
A PTO-based gear transmission mechanism 13 that performs a two-speed shift by shifting is equipped. Further, an intermediate transmission chamber is provided between the rear wall 2a of the main clutch housing 2 and the front wall 3a of the transmission case 3.
14 is formed, and the transmission case front wall 3
The input shaft 1 of the traveling system is inserted into this intermediate transmission chamber 14 from a.
5 is plunged in, the driving shaft 17 whose power is on/off through the main clutch 16 is thrust into the intermediate transmission chamber 14 , and above and below the intermediate transmission chamber 14 are rotating support shafts equipped with hydraulic clutches 18 and 19 . 20,2
1 is supported via a rear wall 2a of the main clutch housing and a bracket 22 attached thereto. The upper hydraulic clutch 18 is fitted loosely between the drive drum 23 and the support shaft 20 by shifting a piston 24 installed in the drive drum 23 fixed to the support shaft 20 to the right using pressure oil. passive drum 2
Friction plates 26, 27, etc. interposed between the drums 23 and 5 are brought into pressure contact with each other to transmit frictional power between the two drums 23 and 25, and by releasing hydraulic pressure to the piston 24, the piston 24 is moved by the internal spring 28. The gear 29 formed on the drive drum 23 is configured to release the frictional power transmission by restoring it to the left, and the gear 3 fixed to the shaft end of the drive shaft 17
It is occluded by 0. A gear 31 integrally formed on the passive drum 25 is freely rotatably supported in the intermediate transmission chamber 14 via a separate support shaft 32.
The input shaft 15 is interlocked with a gear 34 fixed to the shaft end of the input shaft 15 of the travel system. Similarly to the hydraulic clutch 18 , the lower hydraulic clutch 19 includes a driving drum 35, a passive drum 36, and a piston 3.
7. Consisting of friction plates 38..., 39... and a return spring 40, when the gear 41 formed on the drive drum 35 is engaged with the driving shaft gear 30,
A gear 42 formed on the passive drum 36 is directly engaged with the travel system input shaft gear 34. Then, the lower hydraulic clutch 19 is used for normal rotation (forward) transmission.
Further, the upper hydraulic clutch 18 is used for reverse rotation (reverse) transmission. Further, the rear end of the lower rotating support shaft 21 is coupled to a PTO system transmission shaft 43 within the transmission case 3, and both hydraulic clutches 18 , 1
Power is transmitted regardless of whether 9 is on or off. Pressure oil is supplied to and drained from the hydraulic clutches 18 and 19 through internal oil passages 44 and 4 of each rotating support shaft 20 and 21.
5 and both clutches 1
Lubricating oil is supplied to the friction transmission points 8 and 19 via separate internal oil passages 46 and 47. The front ends of these rotating support shafts 20 and 21 are thrust into the main clutch chamber 48 through the rear wall 2a of the main clutch housing, and the thrust shaft ends are connected to hydraulic joints 49 and 5 bolted to the front surface of the rear wall 2a.
0 respectively. Further, a control valve 51 is attached to the upper surface of the main clutch housing 2, and a control valve 51 is connected to the main clutch chamber 48 from this valve 51.
The pipe 52 extending inward is connected to the hydraulic joint 4.
9, 50, and the control valve 51 and each oil passage 44 are connected to each other via the pipe 52 and the oil passages 59, 60, 62 in the joint. In addition, a return spring 63 is provided in the main clutch chamber 48.
Clutch operation sleeve 56 energized by , arm 57 that presses the clutch operation sleeve 56 , and clutch operation shaft 5
8 is equipped. Also, the lubricating oil level L on the front wall a of the transmission case 3
A communication hole 53 is formed in the portion recessed below, and lubricating oil can freely flow between the transmission case 3 and the intermediate transmission chamber 14 through this hole 53. The lubricating oil level L is set approximately near the center of the travel system input shaft 15, and therefore, in the intermediate transmission chamber 14 , the lower forward hydraulic clutch 1
9 is designed to be completely submerged in lubricating oil. Additionally, multi-disc hydraulic clutches generally experience power loss due to rotation when the clutch is disengaged, and when submerged in lubricating oil, the viscosity of the lubricating oil tends to cause more rotation. . For this reason, the hydraulic clutch 18 on the reverse side, which is used relatively infrequently, is provided on the lubricating oil level, and lubricating oil is supplied from the internal oil passage 46 for cooling to the minimum necessary level. Note that the forward hydraulic clutch 19 , which is submerged under the oil surface, is cooled even though it does not necessarily receive lubricant supply from the internal oil passage 47, but it ensures reliable lubricant supply and circulation to the friction transmission section. The oil is supplied from the internal oil passage 47 at the top. FIG. 3 shows a hydraulic circuit for operating the hydraulic clutches 18 and 19 , and the control valve 51 includes a three-position switching valve 64 for switching forward and backward, and a modulating relief for controlling the rise characteristics of the clutch operating oil pressure. It consists of a valve 65, a modulating valve 66, and a relief valve 67 for supplying lubricating oil into each hydraulic clutch 18 , 19 , and the pump port of the control valve 51 is connected to a flow priority valve 68. It is connected to the flow control port of valve 69. The three-position switching valve 64 is configured as a rotary type that can be rotated to three positions by a manual lever.
At the neutral position N, the pressure oil from the pump 68 is drained to the tank port T through the modulating relief valve 65 and the clutch lubrication relief valve 67, and a portion of the relief drained oil is drained from the top of the relief valve 67 to the oil path n. The oil is supplied to the friction transmission parts of both hydraulic clutches 18 and 19 via the pump to lubricate and cool the friction surfaces. In addition, in the forward position F or reverse position R, pressure oil is supplied to the forward hydraulic clutch 19.
The oil is supplied to an oil path f to the hydraulic clutch 18 or an oil path r to the reverse hydraulic clutch 18, and is also supplied to an oil path m to the modulating valve 66 to control the hydraulic clutch operating pressure. The modulating relief valve 65
is urged in the valve closing direction by a spring 70, and
A spring receiver 71 supporting the rear end of the spring 70 is configured to be able to be displaced by pressure oil supplied through an orifice 72 of the modulating valve 66. As a result, the spring pressure, that is, the relief operating pressure, gradually increases. Therefore, when the switching valve 64 is switched from the forward position F to the reverse position R, the operating pressure of the modulating relief valve 65 gradually increases as described above, so that the applied pressure to the selected hydraulic clutch 19 or 18 increases. The clutch force increases gradually, resulting in smooth clutch engagement without shock. As explained above in the embodiments, the tractor transmission structure of the tractor according to the present invention forms an intermediate transmission chamber between the rear wall of the main clutch housing and the front wall of the transmission case, and transmits the intermediate transmission from the main clutch housing to the transmission case. The shaft end of the crude oil that protrudes into the chamber and the shaft end of the travel system input shaft that protrudes from the transmission case into the intermediate transmission chamber are interlocked and connected by multiple gear transmission systems with separate shaft configurations, and each transmission system Since a multi-disc hydraulic clutch that is selectively engaged and operated is interposed in each case, the form of the transmission case itself and the traveling gear transmission mechanism equipped thereon are not changed from those of a general gear change type. Alternatively, it is possible to construct a desired speed change transmission mechanism using a hydraulic clutch system using almost the same method, and it is possible to suppress cost increases by sharing production lines and parts. A portion of the large amount of lubricating oil stored in the transmission case is flowed into the transmission chamber to lubricate and cool the multi-disc clutch, so for example, it is possible to make the intermediate transmission chamber an independent chamber and pour a fixed amount of lubricating oil into it. Compared to the case where the clutch is accommodated, temperature diffusion due to the circulation of lubricating oil is better, and the cooling effect of the hydraulic clutch is higher.

[Brief explanation of the drawing]

The drawings show an embodiment of the transmission structure for a tractor according to the present invention, with FIG. 1 being a side view showing a schematic overall configuration, FIG. 2 being a longitudinal side view, and FIG. 3 being a hydraulic circuit diagram. 1... Engine, 2... Main clutch housing, 2a... Rear wall, 3... Mission case, 3
a...Front wall, 14 ...Intermediate transmission chamber, 15...Travel system input shaft, 17...Driving shaft, 18 , 19 ...Hydraulic clutch, 53...Communication hole.

Claims (1)

[Claims for Utility Model Registration] Engine 1, main clutch housing 2, and transmission case 3 are arranged in series in this order,
Traveling gear transmission mechanism inside transmission case 3
8 and 10 , the rear wall 2 of the main clutch housing 2 is
An intermediate transmission chamber 14 is formed between the main clutch housing 2 and the front wall 3a of the transmission case 3, and the drive shaft 1 projects from the main clutch housing 2 into the intermediate transmission chamber 14 .
7 and the shaft end of the travel system input shaft 15 protruding from the transmission case 3 into the intermediate transmission chamber 14 are interlocked and connected by a plurality of gear transmission systems with separate shaft configurations, and each transmission system has a Multi-plate hydraulic clutches 18 and 19 , which are selectively engaged and operated, are interposed, and a communication hole 53 is provided in the front wall 3a of the transmission case 3 to connect the transmission case 3 and the intermediate transmission chamber 14 . A transmission structure for a tractor, characterized in that it is configured to allow lubricating oil to flow. The gear transmission system in the intermediate transmission chamber 14 is connected to the transmission chamber 1.
4, the gear transmission system located on the lubricating oil surface is configured as a forward transmission system, and the gear transmission system located on the lubricating oil surface is configured as a reverse transmission system. Tractor power transmission structure described in .