JPH0419258Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention fixes a first sprocket for reverse rotation, and a first gear and a second gear for forward rotation to a first transmission shaft,
A second sprocket, which is chain-transmitted to the first sprocket, is loosely fitted onto the second transmission shaft, and
A clutch gear that integrally incorporates a third gear that can engage with the first gear and a fourth gear that can engage with the second gear is slidable in the axial direction of the second transmission shaft and rotates integrally with the clutch gear. The clutch gear can be freely attached, and by shifting the clutch gear, the first gear, the third gear,
The second gear and the fourth gear are selectively engaged with each other to enable two-stage forward and low gear shifting, and further,
The second sprocket and the clutch gear are integrated via an engagement pin by shifting the clutch gear toward the second sprocket, thereby enabling reverse gear shifting, and is used when mounted on a lawn tractor. Regarding the transmission structure.

[Conventional technology]

In this type of transmission structure, the clutch gear was conventionally constructed by fitting a separately configured third gear onto the stepped portion of the fourth gear, and welding the contact surfaces of both together over the entire circumference. At the same time, an engagement pin was welded to one side of the fourth gear.

[Problem that the invention attempts to solve]

It is true that in this case it is easier than manufacturing the third gear and fourth gear integrally, but the process of welding the third gear to the fourth gear takes time, and the process can be shortened. In addition, welding the entire circumference would cause thermal distortion to the gear, and there was also the drawback that one additional step was required to weld the engagement pin.

The purpose of this invention is to narrow down the welding area,
The point is to provide something that can shorten the manufacturing process.

[Means for solving problems]

The characteristic configuration according to the present invention is that the engagement pin is interposed at the joint between the third gear and the fourth gear in the clutch gear, and the engagement pin and each gear are welded and connected to connect the third gear and the fourth gear. The functions and effects are as follows.

[Effect]

That is, by interposing the engagement pin between the contact portions of both gears, the two gears can be integrated by simply welding the engagement pin to both gears separately as a reinforcing material and a connecting material.

Furthermore, since the thrust force along the axial direction does not act much on the clutch gear, welding locations can be limited to only those locations where the engagement pin is interposed.

[Effect of idea]

By effectively utilizing the engagement pin, the welding process, which conventionally required two steps of joining both gears and the engagement pin, can be reduced to a single process of welding the engagement pin. The process can be shortened, and since the welding area is only the area that touches the engagement pin, the influence of thermal strain can be minimized.

〔Example〕

As shown in FIG. 5, a belt, which is one of the transverse transmission mechanisms 2, is stretched from the front engine 1 through the lower left and right flat decks 6, and is connected to the transmission case 19 via the continuously variable belt transmission 3. It is designed to transmit power to. A rear axle 30 is pivotally supported on the transmission case 19, and a mower 10 is disposed between the rear wheel 9 and the front wheel 8, which are pivotally supported on the transmission case 19, to construct a mid-mount type lawn tractor. It is configured.

As shown in FIGS. 3 and 4, the structure of the mission case 19 will be described in detail.

A projecting boss 19A with an upward opening is provided on the front upper surface of the mission case 19, and a vertical input shaft 7 is pivotally supported within this projecting boss 19A by two large and small bearings 4 and 5. A belt pulley as an example of an input rotating body 11 is spline-fitted to the upper end of the vertical input shaft 7, and an output bevel gear 13 is integrally formed at the lower end located inside the transmission case 19. A first transmission shaft 14 extending along the width direction of the machine body is supported below the input shaft 7, and is connected to the output bevel gear 13 and the permanent input bevel gear 1.
5. The first reverse sprocket 16, the forward first gear 17, and the second gear 18 are attached to be rotatable together. A second transmission shaft 20 is supported in parallel at the same height position behind the first transmission shaft 14, and a second sprocket 21, which is transmitted through the first sprocket 16 and the chain 23, is loosely fitted onto this second transmission shaft 20. In addition, a third gear 22A and a fourth gear which can be selectively engaged with and disengaged from the first gear 17 and the second gear 18 are provided.
A clutch gear 22 integrally formed with a gear 22B is spline-fitted to be slidable in the axial direction. The clutch gear 22 can be switched between a low-speed state in which it slides into engagement with the first gear 17 and a high-speed state in which it engages with the second gear 18. Further, the clutch gear 22 is provided with an engagement pin 24 that protrudes toward the second sprocket 21, and is inserted into an engagement hole 21A provided on the second sprocket 21 side by sliding the clutch gear 22 close to it. When engaged, a reverse state can be created, and the overall speed can be changed to two forward speeds and one reverse speed. Said second transmission shaft 20
A brake mechanism 25 is provided at one end of the holder. A third transmission shaft 26 is supported substantially below the second transmission shaft 20, and the second transmission shaft 26 is supported on the third transmission shaft 26.
A fifth output gear 27 spline-fitted to the transmission shaft 20 and a sixth input gear 28 of a permanent bite type are fixed, and a third output sprocket 29 is integrally formed. A rear axle 30 is supported at the rear and upper part of the third transmission shaft 26, and differential pinion gears 31, 31 and differential side gears 32, 32 are mounted at opposing joints of the left and right divided rear axle portions 30A, 30B.
A differential case 33 is provided which is directly pivotally supported. A fourth input sprocket 34 is fitted onto one side of the differential case 33, and this fourth sprocket 34 and the third sprocket 29 are connected to a chain 35.
It is transmitted. However, the left rear axle portion 30A is supported by two bearings 36, 36, and the right rear axle portion 30B is supported by one bearing 37 and a pillow block (not shown) provided on the outer side of the transmission case. , the bearing boss portion of the transmission case 19 protrudes into the grass collection duct (not shown) installation space. As described above, the arrangement space for the mower 10 is saved by forming the recessed space through the ?-shaped arrangement of the first transmission shaft 14, the second transmission shaft 20, and the third transmission shaft 26.

To explain the structure of the clutch gear 22 in detail, as shown in FIGS. 1 and 2, a stepped boss portion 22a of a sliding member is formed with a fourth gear 22B and a groove 22C for a shift fork (not shown). While holding the third gear 22A externally, engaging pins 24 are respectively inserted at two locations in the circumferential direction on the contact mating surface between the third gear 22A and the stepped boss portion 22a. Weld the entire circumference. Then, the engagement pin 24 and the third gear 22A and the fourth gear 22B are welded, and as a result, the third gear 22A and the fourth gear 22B are integrated.

[Another embodiment] (a) As shown in Fig. 6, the third gear 22A and the fourth gear
The gears 22B are arranged with their respective side surfaces facing each other, and an engagement pin 24 is provided that penetrates through the thickness of both gears, and the engagement pin 2 protrudes from the outer side surface of both gears.
Both ends of 4 and the third gear 22A and the fourth gear 22
B may be welded.

(b) This type of transmission can also be applied to agricultural tractors and other general vehicles.

[Brief explanation of the drawing]

The drawings show an embodiment of the transmission structure according to the present invention, and FIG. 1 is a front view of the clutch gear, FIG. 2 is a vertical side view of the clutch gear, FIG. 3 is a developed sectional view of the internal structure of the transmission case, and FIG. 4 is a front view of the clutch gear. FIG. 5 is a side view of the transmission case, FIG. 5 is a side view of the lawn tractor, and FIG. 6 is a vertical cross-sectional side view showing another embodiment of the attachment state of the engagement pin. 14...First transmission shaft, 16...First sprocket, 17...First gear, 18...Second gear, 20
...Second power transmission shaft, 21...Second sprocket, 2
2A...Third gear, 22B...Fourth gear, 22...
...Clutch gear, 24...Engagement pin.

Claims (1)

[Scope of utility model registration request] The first sprocket 1 for reverse rotation is attached to the first transmission shaft 14.
6, and a second sprocket 21 in which the first gear 17 for forward rotation and the second gear 18 are fixed, and the second sprocket 21 is chain-transmitted to the second transmission shaft 20 with the first sprocket 16.
A clutch gear 22 is fitted loosely into the second transmission shaft 20, and a third gear 22A that can engage with the first gear 17 and a fourth gear 22B that can engage with the second gear 18 are integrally assembled. A transmission structure in which the clutch gear 22 is attached so as to be slidable in the axial direction and rotatable integrally with the clutch gear 22, and an engaging pin 24 is provided on the clutch gear 22 to be integrated with the second sprocket 21 by shifting the clutch gear 22. The engagement pin 24 is interposed at the joint between the third gear 22A and the fourth gear 22B in the clutch gear 22, and the engagement pin 24 and the respective gears 22A and 22B are welded together. 3rd gear 2
A transmission structure in which 2A and 4th gear 22B are integrated.