JP2016215918A - transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a structure, to which a long PTO shaft can be attached, in a transmission to which a short PTO shaft can be attached.SOLUTION: A transmission includes: a transmission housing having a rear cover 74; a PTO shaft 36D protruding rearward from an interior part of the transmission housing through a hole of the rear cover 74; an extension case 75 attached to the rear cover 74 and covering a part of the PTO shaft 36D; and a bearing provided in the extension case 75 and supporting the PTO shaft 36D. The extension case 75 is fixed to the rear cover 74.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a transmission, and more particularly to a transmission having a PTO (Power Take-off) shaft.

  2. Description of the Related Art Conventionally, work vehicles capable of connecting work machines (for example, rotary machines) such as tractors are known. Such a work vehicle includes a PTO shaft that protrudes outward from the transmission housing. And the driving force of an engine is transmitted to a working machine by connecting a working machine to a PTO axis | shaft (refer patent document 1).

JP 2007-190967 A

  By the way, there are various standards for the PTO axis depending on the region, for example, a short PTO axis and a long PTO axis. In this case, since the supporting position and the like are different between the short axis and the long axis, the transmission housing and the like are designed for the short axis and the long PTO axis, respectively, and there is no compatibility. For this reason, the number of parts and the number of management man-hours have increased, causing a cost increase. Therefore, there has been a demand for cost reduction by sharing parts.

  An object of the present invention is to provide a transmission capable of attaching a long PTO shaft to a transmission capable of attaching a short PTO shaft.

  The transmission of the present invention includes a transmission housing having a rear cover, a PTO shaft protruding rearward from the inside of the transmission housing through a hole in the rear cover, an extension case attached to the rear cover and covering a part of the PTO shaft, It is set as the structure provided with the bearing provided in the said extension case and supporting the said PTO axis | shaft.

  In the above transmission, the extension case may be fixed to the rear cover.

  Further, in the above transmission, the extension case includes the bearing, and has a cylindrical body with one end attached to the outer surface of the rear cover, a plate-like portion that covers the other end of the cylindrical body, and a through-hole through which the PTO shaft is inserted. It is good also as a structure provided with the cover body which has a hole.

  According to the transmission of the present invention, the extension case including the bearing is attached to the rear cover of the transmission housing. Thereby, since the PTO shaft can be supported behind the rear cover, the long PTO shaft can be attached using the transmission housing for the short PTO shaft. Therefore, when manufacturing a transmission equipped with a short PTO shaft and a transmission equipped with a long PTO shaft, the transmission housing can be shared. Therefore, it is not necessary to design a transmission housing for each of the short shaft and the long shaft PTO shaft, so that the number of parts and the number of management steps can be reduced and the cost can be reduced.

  According to the transmission of the present invention, the extension case can be easily attached to the rear cover by fixing the extension case to the rear cover.

  Further, according to the transmission of the present invention, the extension case can be configured with a cylindrical body and a lid body, so that the extension case can be configured with a part that is easy to manufacture and with a small number of parts.

It is an external appearance perspective view of a tractor. It is a figure which shows the power transmission system of a tractor. It is a figure which shows a transmission. It is a figure which shows the structure of a transmission. It is the figure seen from the arrow F of FIG. It is the figure seen from the arrow R of FIG. It is the figure seen from the arrow L of FIG. It is a figure which shows the structure of a transmission housing. It is a rear view of a rear cover. It is a figure which shows a rear cover, a PTO axis | shaft, and an extension case. FIG. 11 is an exploded view of FIG. 10. It is a longitudinal cross-sectional view of FIG. It is a figure which shows a rear cover, a short PTO axis | shaft, and a cover body.

  The technical idea of the present invention can be applied to all work vehicles such as farm work machines such as tractors, rice transplanters, and combine machines, and special work vehicles such as wheel loaders. Below, it demonstrates using the tractor which is a typical work vehicle.

  First, the tractor 100 will be briefly described.

  FIG. 1 shows a tractor 100. In the figure, the front-rear direction, the left-right direction, and the up-down direction of the tractor 100 are shown.

  The tractor 100 mainly includes a frame 1, an engine 2, a transmission 3, a front axle 4, and a rear axle 5. Further, the tractor 100 includes a cabin 6. The cabin 6 has a cockpit inside, and a driver's seat, an accelerator pedal, a shift lever, and the like are arranged.

  The frame 1 forms a skeleton at the front portion of the tractor 100. The frame 1 constitutes a chassis of the tractor 100 together with the transmission 3 and the rear axle 5. The engine 2 described below is supported by the frame 1.

  The engine 2 converts thermal energy obtained by burning fuel into kinetic energy. That is, the engine 2 generates rotational power by burning fuel. The engine 2 is connected to an engine control device (not shown). When the operator operates an accelerator pedal or the like, the engine control device changes the operating state of the engine 2 according to the operation. Further, the engine 2 is provided with an exhaust purification device 2E. The exhaust purification device 2E oxidizes particulates, carbon monoxide, hydrocarbons, etc. contained in the exhaust.

  The transmission 3 transmits the rotational power of the engine 2 to the front axle 4 and the rear axle 5. The rotational power of the engine 2 is input to the transmission 3 via a coupling clutch. The transmission 3 is provided with a speed change mechanism 3S (see FIG. 2). When the operator operates a shift lever or the like, the speed change mechanism 3S changes the traveling speed of the tractor 100 according to the operation. The transmission 3 is provided with a front wheel drive mechanism 3F and a work machine drive mechanism 3P (see FIG. 2). When the operator operates the select switch, the front wheel drive mechanism 3F changes the drive mode of the front tire 41 according to the operation. When the operator operates a power switch or the like, the work machine drive mechanism 3P changes the operation mode of the work machine (not shown: for example, a rotary) according to the operation.

  The front axle 4 transmits the rotational power of the engine 2 to the front tire 41. The rotational power of the engine 2 is input to the front axle 4 via the transmission 3. The front axle 4 is provided with a steering device (not shown). When the operator operates the steering wheel, the steering device changes the steering angle of the front tire 41 according to the operation.

  The rear axle 5 transmits the rotational power of the engine 2 to the rear tire 51. The rotational power of the engine 2 is input to the rear axle 5 via the transmission 3. The rear axle 5 is provided with a braking mechanism 5B (see FIG. 2). When the operator operates the brake pedal, the braking mechanism 5B reduces or stops the rotational speed of the rear tire 51 according to the operation. In addition, when the operator operates the handle, the braking mechanism 5B can also reduce or stop the rotational speed of one rear tire 51 according to the operation (this function is referred to as an “auto brake function”).

  Next, the power transmission system of the tractor 100 will be described.

  The power transmission system of the tractor 100 mainly includes a transmission 3, a front axle 4, and a rear axle 5. Here, a description will be given focusing on the structure of the transmission 3.

  FIG. 2 shows a power transmission system of the tractor 100. FIG. 3 shows the transmission 3. FIG. 4 shows the structure of the transmission 3. 5 is a view seen from the arrow F in FIG. 4, and FIG. 6 is a view seen from the arrow R in FIG. 7 is a view seen from the arrow L in FIG.

  The transmission 3 includes a hydraulic unit that is operated by hydraulic oil. For example, the forward clutch 321 and the reverse clutch 322 constituting the forward / reverse switching device 32, the constant speed clutch 341 and the speed increasing clutch 342 constituting the front wheel drive switching device 34, the PTO clutch 351 constituting the work machine drive switching device 35, and the like. is there.

  The main transmission 31 can change the ratio of the rotational speeds of the input shaft 312 and the output shaft 313 steplessly. The continuously variable transmission 311 is connected to an input shaft 312 and an output shaft 313. The input shaft 312 is connected to a plunger block 314 that is rotatably supported. The plunger block 314 delivers high-pressure hydraulic oil and functions as a hydraulic pump 31P. The output shaft 313 is connected to a motor case 315 that is rotatably supported. The motor case 315 rotates by receiving high-pressure hydraulic oil and functions as the hydraulic motor 31M. A forward drive gear 316 and a reverse drive gear 317 are attached to the output shaft 313. The forward drive gear 316 and the reverse drive gear 317 transmit rotational power to the forward / reverse switching device 32.

  The forward / reverse switching device 32 can transmit rotational power via either the forward clutch 321 or the reverse clutch 322. The forward clutch 321 has a forward driven gear 323 that meshes with the forward drive gear 316. The forward clutch 321 operates to transmit the rotational power of the output shaft 313 to the center shaft 325. The reverse clutch 322 has a reverse driven gear 324 that meshes with the reverse drive gear 317 via a reverse gear. The reverse clutch 322 is operated to transmit the rotational power of the output shaft 313 to the center shaft 325. An ultra-low speed drive gear 326, a first speed drive gear 327, and a second speed drive gear 328 are attached to the center shaft 325. The ultra-low speed drive gear 326, the first speed drive gear 327, and the second speed drive gear 328 transmit rotational power to the auxiliary transmission device 33.

  The auxiliary transmission 33 can change the ratio of the rotational speeds of the center shaft 325 and the center shaft 337 to a plurality of stages. The ultra-low speed dog unit 331 is adjacent to the ultra-low speed driven gear 334 that meshes with the ultra-low speed drive gear 326. The ultra-low speed dog unit 331 is operated to transmit the rotational power of the center shaft 325 to the center shaft 337. First-speed dog unit 332 is adjacent to first-speed driven gear 335 that meshes with first-speed drive gear 327. The first speed dog unit 332 operates to transmit the rotational power of the center shaft 325 to the center shaft 337. Second speed dog unit 333 is adjacent to second speed driven gear 336 that meshes with second speed drive gear 328. The second speed dog unit 333 is operated to transmit the rotational power of the center shaft 325 to the center shaft 337. A front drive gear 338 and a rear pinion gear 339 are attached to the center shaft 337. The front drive gear 338 transmits rotational power to the front wheel drive switching device 34 via a counter shaft 33D having a front driven gear 33A, a constant speed drive gear 33B, and an increased speed drive gear 33C. The rear pinion gear 339 transmits rotational power to the rear axle 5 via the differential gear unit 33E.

  The front wheel drive switching device 34 can transmit rotational power via either the constant speed clutch 341 or the speed increasing clutch 342. The constant speed clutch 341 has a constant speed driven gear 343 that meshes with the constant speed drive gear 33B. The constant speed clutch 341 is operated to transmit the rotational power of the counter shaft 33D to the center shaft 345. The speed increasing clutch 342 has a speed increasing driven gear 344 that meshes with the speed increasing drive gear 33C. The speed increasing clutch 342 operates to transmit the rotational power of the counter shaft 33D to the center shaft 345. A propeller shaft 346 is attached to the center shaft 345. A front pinion gear 347 is attached to the propeller shaft 346. The front pinion gear 347 transmits rotational power to the front axle 4.

  With such a structure, the transmission 3 can change the traveling speed of the tractor 100 (the traveling speed including the stop). Further, the transmission 3 can change the traveling direction (forward or reverse) of the tractor 100. Further, the transmission 3 can change the driving mode of the front tire 41 (constant speed four-wheel drive, speed-up four-wheel drive or non-drive).

  The work machine drive switching device 35 can transmit rotational power via the PTO clutch 351. The PTO clutch 351 has a driven gear 352 that meshes with the drive gear 318. The PTO clutch 351 transmits the rotational power of the input shaft 312 to the center shaft 353 by operating. The center shaft 353 is provided with a first speed drive gear 354, a second speed drive gear 355, a third speed drive gear 356, a fourth speed drive gear 357, and a reverse drive gear 358. The first speed drive gear 354, the second speed drive gear 355, the third speed drive gear 356, the fourth speed drive gear 357, and the reverse drive gear 358 transmit rotational power to the work machine transmission 36.

  The work machine transmission 36 can change the ratio of the rotational speeds of the center shaft 353 and the center shaft 369 to a plurality of stages. The first dog unit 361 is disposed between the first speed driven gear 364 and the second speed driven gear 365. The first dog unit 361 transmits the rotational power of the center shaft 353 to the center shaft 369 via the first-speed drive gear 354 and the first-speed driven gear 364 as the sleeve slides in one direction. Further, the first dog unit 361 transmits the rotational power of the center shaft 353 to the center shaft 369 via the second-speed drive gear 355 and the second-speed driven gear 365 as the sleeve slides to the other side. Second dog unit 362 is adjacent to third-speed driven gear 366. The second dog unit 362 transmits the rotational power of the center shaft 353 to the center shaft 369 via the third-speed drive gear 356 and the third-speed driven gear 366 as the sleeve slides in one direction. The third dog unit 363 is disposed between the fourth speed driven gear 367 and the reverse driven gear 368. The third dog unit 363 transmits the rotational power of the center shaft 353 to the center shaft 369 via the four-speed drive gear 357 and the four-speed driven gear 367 as the sleeve slides in one direction. Further, the third dog unit 363 transmits the rotational power of the center shaft 353 to the center shaft 369 via the reverse drive gear 358, the reverse gear, and the reverse drive gear 368 as the sleeve slides to the other side. A drive shaft 36A is attached to the center shaft 369. A PTO drive gear 36B is attached to the drive shaft 36A. The PTO drive gear 36B transmits rotational power to the work machine via a PTO shaft 36D having a PTO driven gear 36C.

  With such a structure, the transmission 3 can freely change the operating speed of the work machine (the operating speed including the stop). Moreover, the transmission 3 can change the working direction (forward rotation or reverse rotation) of the work machine.

  Next, the transmission housing 7 will be described.

  FIG. 8 shows the configuration of the transmission housing 7. In the figure, the front-rear direction, the left-right direction, and the up-down direction of the tractor 100 are shown.

  The transmission housing 7 mainly includes a main block 71, a center block 72, a front cover 73, and a rear cover 74.

  The main block 71 is a main structure of the transmission housing 7. The main block 71 is a cast product made of gray cast iron (for example, FC250). The main block 71 has a plurality of bearing holes inside thereof.

  The center block 72 is fixed to the front end surface of the main block 71. The center block 72 is a cast product made of an aluminum alloy (for example, ADC 12). The center block 72 is provided with a plurality of bearing holes inside thereof. The center block 72 is fixed to the main block 71 via a gasket 76. The gasket 76 has a hole for passing a bolt.

  The front cover 73 is fixed to the front end surface of the center block 72. The front cover 73 is a cast product made of an aluminum alloy (for example, ADC12). The front cover 73 is provided with a plurality of bearing holes. The front cover 73 is fixed to the center block 72 via a gasket 77. The gasket 77 has holes for passing bolts.

  FIG. 9 is a rear view of the rear cover 74. The rear cover 74 is fixed to the rear end surface of the main block 71. The rear cover 74 is a cast product made of an aluminum alloy (for example, ADC12). A mounting seat surface 744 for mounting the extension case 75 (see FIG. 10) or the lid 79 (see FIG. 13) of the PTO shaft 36D is formed on the rear surface of the rear cover 74. A plurality of bolt holes 745 are formed in the mounting seat surface 744. The rear cover 74 is provided with a plurality of bearing holes. Specifically, a bearing hole 741 (not penetrating) of the input shaft 312, a bearing hole 742 (not penetrating) of the drive shaft 369, a bearing hole (hole) 743 (penetrating) of the PTO shaft 36 </ b> D, Is provided. The rear cover 74 is fixed to the main block 71 via a gasket 78. The gasket 78 has a hole for passing a bolt.

  Next, the extension case 75 and the lid 79 will be described in detail.

  FIG. 10 shows the rear cover 74, the PTO shaft 36 </ b> D, and the extension case 75. In the figure, the front-rear direction, the left-right direction, and the up-down direction of the tractor 100 are shown. FIG. 11 is an exploded view of FIG. 12 is a longitudinal sectional view of FIG. A PTO shaft cover that surrounds the extension case 75 and the PTO shaft 36D is attached to the rear surface (outer surface) of the rear cover 74, but is not shown here for the sake of clarity.

  The PTO shaft 36D protrudes rearward from the transmission housing 7 through the bearing hole 743 of the rear cover 75. The extension case 75 is attached to the outer surface of the rear cover 74 and covers a part of the protruding portion of the PTO shaft 36D. In the present embodiment, about half of the portion of the PTO shaft 36D protruding from the rear cover 74 is covered with the extension case 75.

  The extension case 75 includes a cylinder body 751 and a lid body 752. A plurality of bearings 36F are provided in the cylindrical body 751. The cylinder body 751 and the lid body 752 are fixed to the rear cover 74 with bolts 753.

  The cylindrical body 751 is a substantially cylindrical metal member having a diameter large enough to cover the bearing hole 743 of the rear cover 74. A mounting seat surface 754 for mounting to the rear cover 74 is formed at one end (front end) of the cylindrical body 751. A cylindrical fitting portion 759 is formed forward from the mounting seat surface 754. The outer surface of the fitting portion 759 is fitted into the bearing hole 743 of the rear cover 75. On the other hand, an attachment seat surface 755 for attaching a lid 752 is formed at the other end (rear end) of the cylinder 751. Four holes penetrating in the front-rear direction for passing the bolts 753 are formed at the edge of the cylindrical body 751.

  A stepped portion 756 is formed on the inner wall surface of the cylindrical body 751 so as to decrease in diameter from the rear to the front. A plurality of bearings 36F are inserted into the cylindrical body 751 from the rear, and the bearings 36F are supported by the step portions 756 and the inner peripheral surface. As the bearing 36F, for example, a rolling bearing such as a slide bearing (flat bearing), a ball bearing (ball bearing), or a roller bearing can be used.

  The lid 752 is a donut plate-like metal member having a plate-like portion 757 that covers the other end (rear end) of the cylindrical body 751 and a through hole 758 through which the PTO shaft 36D is inserted. Four holes penetrating in the front-rear direction for passing the bolts 753 are formed in the edge of the plate-like portion 757. The four holes are formed at positions that overlap the holes of the cylindrical body 751.

  The four bolts 753 are inserted into the holes of the lid body 752 and the cylinder body 751 and screwed into the bolt holes 745 of the rear cover 74. Thereby, the extension case 75 is fixed to the rear cover 74, and the PTO shaft 36D is supported by the bearing 36F.

  As described above, the PTO shaft 36D can be supported behind the rear cover 74 by the extension case 75. Therefore, when the PTO shaft 36D protrudes backward from the rear cover 74, that is, when the long PTO shaft 36D is used. The PTO shaft 36D can be stably supported by the extension case 75. Therefore, the long PTO shaft 36D can be attached using the transmission housing 7 for the short PTO shaft.

  As a result, the transmission housing 7 can be shared when manufacturing a transmission including the short PTO shaft 36E (see FIG. 13) and a transmission including the long PTO shaft 36D. Therefore, there is no need to design a transmission housing for each of the short shaft and the long shaft PTO shaft, and the number of parts, the number of management steps, the number of molds, etc. can be reduced, and the cost can be reduced.

  Further, the extension case 75 can be easily attached to the rear cover 74 by fixing the extension case 75 to the rear cover 74 with bolts. In addition, by configuring the extension case 75 with the cylindrical body 751 and the lid body 752, the extension case 75 can be configured with a component that is easily manufactured and has a small number of components.

  An embodiment using the short-axis PTO shaft 36E described above will be described. FIG. 13 shows a rear cover 74, a short-axis PTO shaft 36E, and a lid 79. In the figure, the front-rear direction, the left-right direction, and the up-down direction of the tractor 100 are shown. A PTO shaft cover that surrounds the PTO shaft 36E is attached to the outer surface (rear surface) of the rear cover 74, but is not shown here for the sake of clarity.

  The short shaft PTO shaft 36 </ b> E protrudes rearward from the transmission housing 7 through the bearing hole 743 of the rear cover 75. The lid 79 is a substantially hexagonal donut plate-shaped metal member having a plate-like portion 791 having a size covering the bearing hole 743 of the rear cover 74 and a through-hole 792 through which the PTO shaft 36E is inserted. Four holes penetrating in the front-rear direction for passing bolts are formed in the edge of the plate-like portion 791. Here, the lid 79 is fixed to the rear cover 74 using two diagonal holes. That is, two bolts are inserted into the holes of the lid 79 and screwed into the bolt holes 745 of the rear cover 74.

  In addition, from the viewpoint of reducing the number of parts, the lid body 752 of the extension case 75 may be used instead of the lid body 79.

36D PTO shaft 36F Bearing 7 Transmission housing 74 Rear cover 743 Bearing hole (hole)
75 Extension case 751 Cylindrical body 752 Lid body 753 Bolt 758 Through hole

Claims (3)

A transmission housing having a rear cover;
A PTO shaft protruding rearwardly from the inside of the transmission housing through a hole in the rear cover;
An extension case attached to the rear cover and covering a part of the PTO shaft;
A transmission provided in the extension case and having a bearing for supporting the PTO shaft.   The transmission according to claim 1, wherein the extension case is fixed to the rear cover. The extension case is
A cylindrical body containing the bearing and having one end attached to the outer surface of the rear cover;
The transmission according to claim 1 or 2, further comprising: a plate-like portion covering the other end of the cylindrical body and a lid body having a through hole through which the PTO shaft is inserted.

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