JPH0125931B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a transmission device used in a work vehicle such as a riding lawnmower.

Riding lawn mowers are operated by an operator who rides on the lawn mower, mowing the lawn by mowing the lawn, and are equipped with two rear wheels, which are driven by a transmission device with the same functions as a car. During lawn mowing work, very low speeds are required, while moving to and from the work site and after work must be done quickly, requiring fairly high speeds, so the range of speed changes is limited. big.

On the other hand, riding lawnmowers are operated by a single person, so they are small in both the front and back directions and the left and right directions, and are constructed compactly.Therefore, they require a compact transmission, and they are work vehicles. Therefore, due to cost and other requirements, the transmission is required to be simple while satisfying the above conditions, as well as functionality and
Sufficient reliability is also required.

Conventionally, such a transmission device has been disclosed in U.S. Patent No.
No. 4103566 is known, as shown in FIG.

That is, in the prior art, an input shaft 52 is mounted horizontally in the middle part of a transmission case 51, a transmission shaft 53 is mounted forward in the figure parallel to the input shaft 52, and a differential gear 56 is mounted parallel to the drive shafts 54, 55 of the wheels. It is located at the rear in the figure. An input driven bevel gear 57 is provided in the axially intermediate portion of the input shaft 52 by spline fitting or the like with the input shaft, and is driven by a driving bevel gear of a propulsion shaft (not shown). Driving gears 58A to 58E, which have smaller diameters adjacent to the gear 57 and whose diameters increase sequentially in the direction of the shaft end, are provided in a part biased to one side from the middle part of the shaft 52 so as to rotate together with the shaft 52 by a spline or the like. There is.

On the other hand, on the parallel transmission shaft 53, transmission driven gears 59A to 59E, which have a small diameter at the shaft end side and gradually increase in diameter toward the middle part of the shaft, are fitted and supported so as to be rotatable with respect to the shaft 53. Gear 59A~59
E meshes with the opposing one of the gears 58A to 58E, so the input to the gear 57 drives the shaft 52, the gears 58A to 58E drive the gears 59A to 59E, and the gears 59A to 59E are idle on the shaft 53. . Engagement grooves 59a are provided in a portion of the inner diameter portion of each of the above-mentioned speed change driven gears 59A to 59E, and 59b between the gears is a spacer ring.

A reverse driven sprocket 60 is loosely fitted into the intermediate portion of the speed change shaft 53 on the opposite side of the gear arrangement portion, and a cylindrical boss portion 60a extending in a direction near the end of the sprocket is used as a spacer to connect the shaft. An output gear 61 is provided at the end of the input shaft 53 through spline engagement or the like, and a drive sprocket 62 and a chain 63 are provided so that the sprocket 30 and the previously mentioned gear 57 of the input shaft 52 are separated in the axial direction and rotate together. Connect via. The output gear 61 meshes with a large-diameter driven gear 65 provided at the end of a final gear 64 that loosely fits around the outer end of the sprocket 62 of the input shaft 52, and the final gear 64 is provided in a differential cage 66 of the differential gear 56. gear 6
7.

By the way, the speed change operation mechanism is the gear 59 of the speed change shaft 53.
A slider 68 provided between the sprocket A and the sprocket 60 and fitted only slidably on the shaft therebetween;
The slider 68 is provided with an engaging rod 69 that can swing in the radial direction provided on one end side, and a protrusion 70 provided on the other end side.
The inner end surface of the sprocket 60 has a recess 60a that engages and disengages the protrusion 70, and these 70 and 60a constitute a dog clutch.

In the above, the diagram shows a neutral state,
By moving the shift fork 71 to the right in the figure, the engagement portion 69a at the tip of the engagement rod 69 is connected to the gears 59A to 5.
9E selectively engages with the engagement grooves 59a... according to the stroke, and obtains a rotational driving force of a predetermined gear ratio to rotationally drive the shaft 53, and the power is transmitted to the gears 61, 65, 64.
is transmitted to the differential gear and output to the axles 54 and 55. Note that the engagement rod 69 is allowed to swing by a groove 53a provided in the shaft 53. When reversing, the slider 68 is moved to the left from the position shown in the figure, so that the protrusion 70 and the recess 60a engage, thereby causing the sprocket 62 to attach to the shaft 53.
The output of is transmitted, and the already mentioned systems 61, 65, 64,
At 67, the axles 54 and 55 are reversed to perform a backward movement.

In the above-mentioned prior art, forward transmission gear groups 59A to 59E are distributed on both ends of the shaft 53 in the axial direction, and a reverse sprocket 60 is distributed on the other end, and a shift operation mechanism is provided between them. The output gear 61 must be provided at the outer end on the side of the sprocket 60 so as not to interfere with the shift operation mechanism. As a result, the gears and sprockets of the input shaft 52 on the drive side must be arranged in a corresponding manner, and as a result, the axial lengths of the transmission shaft 53 and input shaft 52 become longer, and gears 61 and 65 are provided at the shaft ends. Coupled with this, the width of the transmission including the transmission case 51 becomes larger, and secondly, the differential device 56 has gears 61 and 65.
Since the gear 67 of the differential device 56 has to be placed biased toward one end, the left and right axles 54 and 55 are of equal length from the center line of the vehicle body. In addition, the input shaft 52
This is disadvantageous in terms of space utilization because the space on the axle side of the gears 58A to 58E cannot be used due to the above layout, and the arrangement of the differential device is not suitable for the gears 58A to 58E.
Since the bevel gear 57 and other mechanisms are located in this portion on the opposite side of E in the axial direction, the length in the front-rear direction increases, and the length of the transmission case 51 increases.

In this way, the entire transmission becomes large in size and is also disadvantageous in terms of weight.

The present invention has been made in view of the above, and its purpose is to make it possible to reduce the dimensions in both the width direction and the front-back direction compared to the conventional one, and to make the transmission device more compact and lightweight. It is an object of the present invention to provide a transmission device that is capable of moving the vehicle, and also enables the differential device to be disposed as close to the center line of the vehicle body as possible, which is also advantageous in terms of wheel drive.

In order to achieve the above object, the present invention provides a driven bevel gear, a reverse sprocket, and a plurality of forward drive gears that are integrally arranged adjacent to each other on an input shaft, and that the sprocket is mounted on a speed change shaft that is arranged parallel to the input shaft. A sprocket connected to the gear and a forward speed change gear that meshes with the gear are loosely connected, and the sprocket and the gear have an engagement groove on the inner diameter part, and a speed change shaft that can only be slid in the axial direction and has an engagement groove. An engagement rod with an engagement portion that selectively engages and disengages is provided, an output gear integrated with the transmission shaft is provided at the outer end of the transmission gear group, and the gear is connected to an input gear provided on the intermediate shaft. The gist is that the final output gear provided on the intermediate shaft is meshed with the gear provided on the differential cage of the differential device.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 schematically shows a riding lawn mower 1 as an example of a work vehicle in which the present invention is implemented, in which an engine 3 is mounted on the front part of a body 2, and a seat 4 is mounted on the rear part.
A front wheel 5 serving as two steering wheels and two rear wheels 6, 6 serving as driving wheels are provided at the front and rear lower portions.
A housing 8 is provided at the lower part of the middle to cover lawn mowing cutter blades 7, 7 arranged in the front and rear.
The blades 7, 7 are driven by a belt drive mechanism 9 that extends in front of the engine 3 and includes a drive pulley, a direction change pulley, a driven pulley, a belt, and the like.

A propulsion shaft (propeller shaft) 10 extending rearward from the rear of the engine 3 so as to be inclined slightly downward drives rear wheels 6, 6 via a transmission 11.

Fig. 2 is an enlarged sectional view showing the transmission, a developed cross-sectional plan view taken along the line 2-2 in Fig. 1, and Fig. 3 is an enlarged view of the main parts. An output bevel gear portion 101 is provided at the end of the propulsion shaft, and the transmission mechanism and differential device including the bevel gear are surrounded by a transmission case 111 and protected from the outside. In the example, it is made up of a joined body of left and right halves 112 and 113, and the tip of the propulsion shaft 10 is covered with a cover 114.

An input shaft 12 is provided at the rear of the propulsion shaft 10 so as to be perpendicular to the shaft 10. The input shaft 12 is arranged so as to cross the case 111 in the vehicle width direction, and both ends are provided with bearings 13 in the left and right halves 112, 113. , 13. An input (driven) bevel gear 14 is provided on one end of the input shaft 12 on the propulsion shaft 10 side by spin fitting or the like, and the gear 14 is meshed with the bevel gear 101 of the propulsion shaft 10 . A reverse drive sprocket 15 is provided adjacently to the axially inner side of the gear 14 of the input shaft 12, and a forward drive gear 16 is disposed on the shaft from the axially inner side of the sprocket toward the other end. Since the gears 16 in this embodiment have five forward speeds, five gears 161 to 165 are provided adjacent to each other. The innermost gear 161 in the axial direction has the smallest diameter, and the diameter increases sequentially toward the end, and the end 165 located inside the case half 112 on the left side in the figure has the largest diameter. Now, the first speed one 161 is connected to the shaft 12
The second speed 162, third speed 163, fourth speed 164, and fifth speed 165 are spline-fitted onto the shaft 12 and integrated.

As a result of the above, the output of the propulsion shaft 10 is
01, is transmitted to the input shaft 12 via the bevel gear 14, and drives the sprocket 15 and gears 161-165.

A speed change shaft 17 is arranged parallel to the rear of the input shaft 12, and the speed change shaft 17 is longer than the input shaft 12, and its left end 171 in the figure is connected to the shaft support 112 of the left half body 112 of the case.
a through a bearing 18, and the right end 172 is long and extends laterally from this end of the input shaft 12, so that this part of the right half 113 of the case is extended outwardly. The bulge 113b is bulged, and the bulge 113b
The right end 172 is supported via a bearing 18 on a shaft support 113a provided at the shaft support 113a.

On the speed change shaft 17, the sprocket 1 is installed in the middle part.
5 and the corresponding reverse driven sprocket 19, and a neutral collar 20 having a smaller diameter than the subsequent gears is loosely connected to the inner side of the rear driven sprocket 19.
The forward speed change gears 21 are sequentially disposed adjacent to each other and are loosely arranged adjacent to each other. The first gear 211 adjacent to the collar 20 at the center has the largest diameter and meshes with the smallest gear 161 of the gears 16 to obtain the minimum reduction ratio, and the second to fifth gears 212 to 215
gradually decreases its diameter, and the fifth gear 2 at the end
15 is the smallest type and has the maximum diameter of the gear mentioned above 165
meshes with other gears 212 to obtain the maximum reduction ratio.
214 meshes with each of the other intermediate gears 162-164. In addition, 22... in the figure is a ring-shaped spacer interposed between the gear, sprocket, and collar.
The gears 211 to 215, the collar 20, and the sprocket 19 have engaging recesses 211a to 215a, 20 that extend outward in the radial direction and are spaced apart by, for example, 180 degrees.
a, 19a are provided.

On the above-mentioned transmission shaft 17, there is an engagement rod 2 which is long in the axial direction inside the inner diameter of the gear, collar, and sprocket.
3 and 23 are provided 180 degrees apart and slidable in the axial direction, and the shaft 17 is provided with key grooves 173 and 173 for receiving the engaging rods 23 and 23 in the axial direction. Engagement rod 2
3 and 23 are a main body 231 having approximately the same length as the total length in the axial direction of the gears 215 to 211, the collar 20, and the sprocket 19, an engaging portion 232 provided at the tip and protruding in the radial direction, and a base end of the main body. A base portion 233 is provided and protrudes in the radial direction. base 23
3 is a slider 24 slidably fitted onto the shaft 17;
The main body 231 is fitted into a notch in the tip 241 and swings freely with a pin 242, that is, the main body 231 is pivoted on a shaft so as to be able to approach and move away from the main body 231, and a middle part protrudes outward in the radial direction. Cylindrical portions 243, 243 are provided,
Openings 244, 244 are made in the lower part of the front wall of this, and opening 2
44, 244, the base extension portion 2 of the engaging rod 23, 23
34, 234 are loosely engaged, and the balls 246, 246, which are urged inward by springs 245, 245, are inserted into the cylindrical portion 24.
3, 243, and the balls 246, 246 are brought into contact with the extension parts 234, 234, and the extension parts 234,
234 is always elastically biased inward in the radial direction, and as a reaction force is elastically biased so as to lift the engaging portion 232 at the tip of the main body 231 outward in the radial direction. In the figure, 247 is a spring stopper.

A ring upper groove 249 is provided on the outer periphery of the base 248 of the slider 24, and a pin 252 provided at the tip of the bifurcated leg piece 251 of the shift fork 25 is engaged with the ring upper groove 249, and the base 253 of the shift fork 25 is inserted into the ring groove 249. It is connected to a support shaft 254 that is operated by an external operating mechanism, such as a gear shift lever.

In the above, the drive gears 161 to 16 described above
5. The sprocket 15 is driven by the transmission gear 211
~215 and sprocket 1 via chain 26
9, and in the case of neutral, these 211-215, 19 rotate on the shaft 17. Both figures show the fifth gear position where the reduction ratio is the largest, and the engaging portion 232 of the engaging rod 23 engages with the groove 215a provided in the inner diameter part of the fifth gear 215, so that the gear 1
The power of gear 65 is transmitted to the speed change shaft 17, causing it to rotate at high speed, and the other gears 211 to 214 and sprocket 19 are not in engagement or opening, so they idle. When the shift fork 25 is swung counterclockwise in the figure by the rotation of the shaft 254, the slider 24 moves to the right on the shaft 17, and the engaging portion 232 is moved in the radial direction by the spacer 22 against the spring 245 and ball 246. It swings inward and engages the front groove 214a to downshift.
Further rightward movement engages the groove 20a of the neutral collar 20 via the grooves 213a to 211a, thereby cutting off the transmission of power from the shaft 12 to the shaft 17. By operating the shift fork 25 in the opposite direction, the engaging portion 232 engages with any one of the grooves 211a to 215a, and travels in 1st to 5th gears, and further right movement from the neutral collar 20 causes the vehicle to move backward. The engaging portion 232 engages with the groove 9a of the sprocket 19, and the chain 2
The reversing driving force for reversing is transmitted to the sprocket 19 via the sprocket 6 and is transmitted to the shaft 17 to perform the reversing.

A drive gear 27 is provided at the tip of the gear 232 of the above-mentioned speed change shaft 17 so as to rotate integrally therewith, and is engaged with a large diameter gear 281 at the shaft end of an intermediate shaft 28 which is provided adjacently and parallel to the lower side of the shaft 17. Finally, the intermediate shaft 28 is provided with a final output gear 282 at an axially intermediate portion,
Both ends 283 and 284 of the intermediate shaft 28 are connected to the half body 11
Bearings 2 are attached to the shaft supports 112c and 113c of 2,113.
It is rotatably supported via 9 and 29.

The case 11 extends downward, and has an extending portion 111a.
Hollow extensions 112d and 113d are provided on the left and right sides of the axles 30 and 31, and the bases and intermediate portions of the left and right axles 30 and 31 are supported via bearings 32.
A differential device 33 is disposed in between, a gear 332 provided around the differential cage 331 is meshed with the gear 282, and pinions 334, 334 are freely connected to a pinion shaft 333 provided through the intermediate portion of the cage 331. Then, side gears 301 and 311 provided at opposing shaft ends of the axles 30 and 31 are meshed therewith. As a result, the power of the transmission shaft 17 is transferred to the gears 27, 281,
It will be transmitted to the left and right axles 30 and 31 via 282, 332, 334, 301, and 311.

Next, to explain the action and effect in detail, the propulsion shaft 10
As is known, the power is transmitted to the input shaft 12 to drive the sprocket 15 and gears 161 to 165, and the power is transmitted to the intermediate shaft 2 by selectively engaging one of the transmission gears 211 to 215 or the reverse driven sprocket 19.
8, the differential gear 33 and the axles 30 and 31 are transmitted.

By the way, gears 16, 2 on shafts 12, 17
Since the gears 16 and 21 are arranged adjacent to the reverse sprockets 15 and 19, the width of the case 111 is significantly smaller than before, and the speed change operation system 23, Only the portions 24 and 25 are extended outward, and the overall width is reduced. In addition, since gears and reversing sprockets are not distributed on both sides of the shafts 12 and 17 in the axial direction, the shafts 12 and 17 are shortened, and there is no need for a shaft support structure in the middle, reducing the shaft diameter and weight. .
In addition, since the gears 16, 21 and sprockets 15, 19 are arranged adjacent to each other, the differential device can be arranged close to these in the front-rear direction, thereby reducing the overall front-rear dimension as much as possible, and achieving the above-mentioned advantage. At the same time, it is possible to make the overall model more compact and lightweight while maintaining sufficient shifting function.Furthermore, the differential device can be placed close to the center line of the vehicle body, making the axles 30 and 31 approximately the same length, which improves balance when turning. Improves performance and functionality.

The present invention has the advantages as described above.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a side view of a riding lawn mower, FIG. 2 is a developed cross-sectional plan view of a transmission, and FIG. 1 is a sectional view taken along line 2-2, and FIG. is an enlarged view of the same main part, and FIG. 4 is a similar view of a conventional example. In the drawing, 10 is a propulsion shaft, 101, 14 are bevel gears, 12 is an input shaft, 15, 19 are sprockets, 161 to 165, 211, 215 are gears, 1
7 is a gear shift shaft, 23, 24, 25 are shift mechanisms, 2
8 is an intermediate shaft, and 33 is a differential device.

Claims (1)

[Scope of Claims] 1. A driving bevel gear disposed in the front-rear direction and integrally provided at an end portion meshes with the propulsion shaft incorporated in the transmission case, and a driving bevel gear disposed in the left-right direction and meshing with the driving bevel gear on one end side. an input shaft integrally equipped with a driven bevel gear, one end of which is supported on one side wall of the mission case substantially on an extension of the propulsion shaft, and the other end of the input shaft is supported on the other side wall of the mission case; a retraction drive sprocket that is disposed on the input shaft next to the driven bevel gear and is integral with the input shaft; a forward drive gear train integrated with the input shaft, the outer diameter of which increases sequentially from the drive sprocket side to the other end of the input shaft; a speed change shaft that is supported on a bulge formed on one side wall and whose other end is supported on the other side wall of the transmission case; a reverse driven sprocket that is rotatable relative to the speed change shaft and is connected to the reverse driven sprocket by a chain; a forward driven gear train that is rotatable relative to the transmission shaft and that has an outer diameter that gradually decreases toward the other end and meshes with the forward driving gear train; A drive gear disposed between the other ends and integral with the speed change shaft; and a drive gear slidably engaged from one end side in a keyway formed on the outer periphery of the speed change shaft from approximately the middle part to the other end side. an engaging member that selectively engages with each concave portion formed in the inner diameter of the reverse driven sprocket and the forward driven gear train; a slider that is slidably disposed on an extension toward one end on the outer periphery of the shaft and rotates integrally with the speed change shaft; and a slider that is rotatably connected to the outer periphery of the slider;
and a shift member disposed within the bulge of the one side wall of the mission case, which is arranged in the left-right direction, one end of which is rotatably supported by the one side wall of the mission case, and the other end of which is supported on the one side wall of the mission case. an intermediate shaft supported on the other side wall; a driven gear disposed on the other end of the intermediate shaft and meshing with the drive gear and integral with the intermediate shaft; and a driven gear adjacent to the driven gear and on the intermediate shaft. an output gear disposed approximately in the middle of the vehicle body and integrated with the intermediate shaft; left and right axles disposed in the left-right direction and supported on one side wall and the other side wall of the transmission case, respectively; and approximately on the center line of the vehicle body. A transmission comprising: a differential device disposed on the left and right axles and interposed between the left and right axles; and an input gear integrally provided on the outer periphery of a cage of the differential device and meshing with the output gear. Device.