JPH062060Y2 - Mobile work vehicle transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention relates to a transmission suitable for a relatively small traveling work vehicle such as a walk-type lawn mower having a traveling drive mechanism or a riding mower tractor having a mid-mount mower. .

More specifically, the present invention is a key shift type in which a plurality of shift gear trains provided between a drive shaft and a shift shaft are selectively operated by a shift key provided on the shift shaft to obtain multiple shifts. The present invention relates to a transmission of a traveling work vehicle configured with a transaxle type by equipping a transmission case having a transmission with left and right axles.

2. Description of the Related Art Transmissions for such traveling work vehicles generally perform shifting at low torque as disclosed in, for example, U.S. Pat. No. 4,103,566, JP-A-60-104835, and JP-A-61-116154. After that, in order to increase the driving force of the vehicle, it has been considered that the transmission path between the shift shaft and the axle of the key shift type transmission is constituted by a gear reduction mechanism.

For example, in the transmission disclosed in U.S. Pat. No. 4,103,566 among the above documents, the drive shaft is arranged at an intermediate position between the speed change shaft and the axle, and two large and small gears loosely fitted on the drive shaft are used. Two reduction gear trains are provided between the vehicle and the axle. Further, in the one disclosed in JP-A-60-104835, an intermediate shaft is additionally provided between the transmission shaft and the axle, and the transmission shaft and the intermediate shaft and the intermediate shaft and the axle are connected by a reduction gear train. . In Japanese Patent Laid-Open No. 61-116154, a reduction gear train is provided between the transmission shaft and the axle to reduce the speed by only one stage.

In any of the transmissions described above, a differential device is arranged between the left and right axles to facilitate the turning of the vehicle, and the input gear of the differential device is used as the final end gear of the gear reduction mechanism. .

Problems to be solved by the invention In a small traveling work vehicle equipped with a transaxle type transmission, the mission case located between the left and right drive wheels does not restrict the arrangement of working members such as cutting blades. In addition, the front and rear width and the vertical width of the mission case are required to be small so that the ground clearance of the vehicle is not lowered.

In this respect, the conventional transmission described above has a transmission gear case in which the front-rear width or the vertical width of the transmission case is expanded by that amount, and it is desired to further reduce the width of the transmission case.

Therefore, the main object of the present invention is to equip a transmission case equipped with a drive shaft, right and left axles concentric with the transmission shaft, and a gear shift mechanism between the transmission shaft and the axle in a transmission case containing a key shift type transmission. A new transmission for a traveling work vehicle is provided, in which the width of the transmission case as viewed in the direction crossing a plurality of axes arranged in parallel as described above is greatly reduced.

Technical measures taken to solve the problems As shown in FIGS. 1 and 8 respectively, the present invention has left and right axles 1 concentrically arranged with a drive shaft 11 and a speed change shaft 12.
A mission case 10 equipped with 3 and 14 in parallel with each other, and a drive shaft 1 in the mission case 10.
Gears 16F ₁ , 16F ₂ , 16F ₃ , fixedly installed on the
16F ₄ , 16F ₅ and the gear 1 loosely fitted on the transmission shaft 12
7F ₁ , 17F ₂ , 17F ₃ , 17F ₄ , 17F ₅ are provided with a plurality of rows of transmission gear trains, and the gears on the transmission shaft 12 can slide in the long grooves 18 on the outer peripheral surface of the transmission shaft. Key shift type transmission 15 for performing multi-stage gear shifting by selectively connecting to the shift shaft by the clutch protrusion 19a of the shift key 19, and rotation of the shift shaft 12 in the transmission case 10 to the left and right axles 13 and 14. And a reduction gear mechanism 20 for decelerating and transmitting the transmission.

In this transmission, the present invention solves the above-mentioned problems by similarly forming the transmission shaft 12 as a hollow shaft and arranging the left and right axle shafts 13 and 14 as shown in FIGS. 1 and 8, respectively. One of the axles 1
4 is provided so as to penetrate the speed change shaft, and an intermediate shaft 21 that is substantially concentric with the drive shaft 11 is provided inside the transmission case 10 so that the reduction gear mechanism 20 includes the speed change shaft 12 and the intermediate shaft 21.
First reduction gears 22 and 23 arranged between and intermediate shaft 21
And the second reduction gear 2 arranged between the left and right axles 13 and 14
It consisted of 4,25 rows.

The rotation of the speed change shaft 12 driven by the drive shaft 11 via the key shift type speed change device 15 is changed to the first reduction gear 2
2, 23 rows and the second reduction gears 24, 25 rows reduce the speed in two stages and transmit the reduced gears to the left and right axles 13, 14.
3, 14 are driven with high torque.

Since one of the axles 14 is provided so as to pass through the hollow transmission shaft 12, the transmission shaft 12 and the left and right axles 13, 14 are concentrically arranged, and the drive shaft 11 and the intermediate shaft 21 are substantially concentric. Since they are arranged, the width of the mission case 10 when viewed in the direction transverse to the above axes is substantially parallel.
It is equal to the corresponding width of the mission case that houses the transmission with the book transmission shaft. Therefore, the front and rear width occupied by the mission case 10 is reduced in the work vehicle that extends along the transverse direction of the vehicle in the front-rear direction of the vehicle, and the work case 1 extends in the work vehicle that extends along the vertical direction of the vehicle.
The vertical width occupied by 0 is reduced. Intermediate shaft 2 arranged as described above
The width of the mission case 10 along the direction of the axles 13 and 14 is slightly enlarged because the transmission No. 1 is provided, but in the case of a transaxle type transmission, there is no problem because the mission case need only be housed between the left and right drive wheels. This is advantageous in stably supporting the axle by providing a large gap between the two bearings that support the axles 13 and 14.

In order to facilitate the traveling of the vehicle, the driven-side reduction gear 25 of the second reduction gear train is loosely fitted and installed on the left and right axles 13 and 14 as illustrated in FIG. Therefore, the left and right side clutches 26 and 27 are arranged between the reduction gear 25 and the left and right axles 13 and 14, or, as illustrated in FIG. The moving device 30 may be arranged between the left and right axles 13 and 14.

In the structure in which the left and right side clutches 26 and 27 are provided as shown in FIG. 1, it is preferable to provide left and right side brakes 28 and 29 that are operated after the clutches 26 and 27 are disengaged. Both can be operated simultaneously to be used as a traveling brake. Further, in the structure in which the differential device 30 is provided as shown in FIG. 8, the traveling brake 31 can be provided by being arranged on the intermediate shaft 21 provided for installing the reduction gear mechanism 20.

Embodiment FIG. 1-6 shows a first embodiment, and FIG. 7 shows a walk-behind lawnmower equipped with a transmission according to the first embodiment.

In the lawn mower shown in FIG. 7, the left and right front wheels 34 are rotatably supported by a deck 33 that constitutes a machine frame, and
The mission case 10 shown in FIG. 1 is fixedly mounted on the rear end portion, and the left and right rear wheels 35, which are drive wheels, are attached to the left and right axles 13 and 14. An engine 36 as a drive source is mounted on the deck 33, and a lawn mowing blade 37 that is rotationally driven by the engine 36 is provided on the lower surface side of the deck 33.

A pulley 38 is fixedly installed on an output shaft 36a of the engine 36, and a belt 41 is wound between the pulley 38 and a pulley 40 attached to an input shaft 39 protruding upward from the transmission case 10. . Belt 41
Tension clutch 4 that makes transmission possible by tensioning the
2 is provided on the upper surface of the deck 33, and the tension clutch 42 is attached to the deck 33 and is provided with a main clutch lever 44 attached to a steering handle 43 extending rearward and upward. It is turned off via.

As shown in FIG. 2, the mission case 10 has upper and lower halves joined by horizontal mating surfaces, but the input shaft 39 is rotatably supported by a tubular portion 46 integrally formed in the upper case half. It is provided so as to straddle the inside and outside of the mission case 10. A small-diameter bevel gear 47 is integrally formed at the lower end of the input shaft 39. The bevel gear 47 is a large-diameter bevel gear 48 fixed to the drive shaft 11 by spline fitting as shown in FIG. Is meshed with.

As shown in FIG. 1, the drive shaft 1 is attached to the mission case 10.
1, the transmission shaft 12, the axles 13 and 14, and the intermediate shaft 21 are mounted in the above-described arrangement, and the axes of these shafts are substantially on the same horizontal plane. The bearings that support the respective shafts are fitted and held in the semicircular groove holes formed in the mating surfaces of the upper and lower case halves of the transmission case 10 so that the half portions are fitted. The axle 13 on the opposite side of the speed change shaft 12 is supported by an outwardly facing cylindrical portion 49 integrally projecting from the transmission case 10 via a pair of ball bearings 50, 51 provided at relatively large intervals. The axle 14 penetrating the hollow transmission shaft 12 has a pair of ball bearings 52, 53 arranged outside the transmission shaft 12 and widely spaced apart from each other.
It is supported by the mission case 10 via.

The gears 16F ₁ -16F ₅ on the drive shaft 11 are
5 are provided by spline fitting, and correspondingly, the five gears 17F _{1 to} 17F ₅ are also loosely fitted and installed on the transmission shaft 12. Between the drive shaft 11 and the speed change shaft 12,
A reverse drive train formed by winding a chain 54 around a sprocket gear 16R fixedly installed on the drive shaft 11 and a sprocket gear 17R loosely installed on the transmission shaft 12 is also provided. Therefore, the gear 17F ₁ − on the transmission shaft 12
By selectively connecting one of the 17F ₅ to the transmission shaft 12, the vehicle speed from the first forward speed to the fifth forward speed can be obtained.
By selectively connecting the sprocket gear 17R to the transmission shaft 12, a reverse first speed can be obtained.

Three long grooves 18 are provided on the outer peripheral surface of the transmission shaft 12, and three shift keys 19 are provided in each long groove 18 as shown in FIG. As is customary in key transmissions, the gear 17F ₁ on the transmission shaft 12 −
17 F ₅ and the sprocket gear 17 R are formed with slots corresponding to the number of shift keys 19 on the inner peripheral surface of the boss portion, and the clutch projections 19 a of each shift key 19 are formed.
Penetrates into the slot and connects the gear to the transmission shaft 12.
On the transmission shaft 12, as usual, the shift key 1
A shifter sleeve 55 to which the base end of 9 is attached is slidably installed. Each shift key 1 as shown in FIG.
The leaf spring 56 for urging the clutch projection 19a so that the clutch projection 19a projects radially outward from the inside of the long groove 18,
The convex portion 19b formed on the inner surface of the proximal end of the shift key 19 is gripped and attached to the shift key 19, and a portion near the tip is bent to slidably contact the inner bottom surface of the long groove 18 and then the distal end portion is attached. The shift key 19 is elastically applied. The shifter sleeve 55 shown in FIGS. 1 and 3 is supposed to be shift-operated via a line 58 by a speed change lever 57 provided on the steering handle 43 as shown in FIG. 7, and is shown in FIG. As described above, the operation shaft 59 for displacing the shift fork (not shown) for the shifter sleeve 55 is extended rearward from the inside of the mission case 10.

As shown in FIG. 4, one end of the hollow transmission shaft 12 has a reduced diameter, and a long groove 18 is formed on the outer peripheral surface of the transmission shaft 12 over the entire length of the transmission shaft 12 from the reduced diameter portion. A large number of gear teeth 18a are formed on the outer peripheral surface of the diameter reducing portion. As shown in FIG. 1, the gear 22 on the small diameter side in the first reduction gear train is engaged with the transmission shaft 12 so as not to rotate relative to the gear shaft by gear teeth on the inner peripheral surface that mesh with the gear teeth 18a. . The gear 23 on the large diameter side in the first reduction gear train and the gear 24 on the small diameter side in the second reduction gear train are spline-fitted to the intermediate shaft 21, respectively.

In the first embodiment, the left and right side clutches 26 and 27 are provided as shown in FIG. 1, and the right side clutch 27 is shown in an enlarged scale in FIGS. The reduction gear 25, which is loosely fitted over the left and right axles 13 and 14, is integrally formed with an annular protrusion 25a which is in sliding contact with the axles 13 and 14, and is integrally formed on the boss. Two holes 60 are formed on each side of the axles 13 and 14. Corresponding two holes 61 for each axle 13,1
4 is formed in a cut shape from the inner end face side, and has a hole 60,
A ball 62 is inserted and installed so as to straddle 61. A clutch sleeve 63 having an inner surface portion slidably contacting the overhanging portion 25a is slidably provided on the inner end portion of each axle 13, 14, and a ball 62 is provided at the inner surface portion end of each clutch sleeve 63. Is the hole 61 of the axles 13 and 14
An inclined surface 63a is provided so as to abut on the withdrawn state.

As described above, the side clutches 26 and 27 connect the gear 25 and the axles 13 and 14 via the balls 62 when the clutch sleeve 63 prevents the balls 62 from being pulled out from the holes 61 as shown in FIG. Then, as shown in FIG. 3, when the clutch sleeve 63 is slid to the opposite side of the gear 25, the centrifugal force based on the rotation of the gear 25 causes each axle 1 to move.
The gears 25 and the axles 13 and 14 are pulled out from the holes 61 of the gears 3 and 14 and contact the slopes 63a to disconnect the gears 25 from the axles 13 and 14.

As described above, the clutch sleeve 63 is slid to disengage the clutch, and thereafter the sleeve 63 is slid in the direction of the gear 25 to push the ball 62 into the push hole 61 by the inclined surface 63a to disengage the clutch. To enter, there are left and right shift forks 64 engaged with the clutch sleeve 63, FIG. 6 showing one of them. An operating shaft 65 is fixed to the shift fork 64, which has engaging portions 64a that project into the annular groove on the outer peripheral surface of the clutch sleeve 63 at both ends of the arcuate shape, at an offset position. The operation shaft 65 that rotates the shift fork 64 and slides the clutch sleeve 63 by the rotational displacement is
It is fitted and supported in semicircular groove holes 66 formed in the mating surfaces of the upper and lower case halves of the mission case 10. As shown in FIG. 1, two slots 66 are formed in each half of the case so as to correspond to the left and right side clutches 26, 27. A clutch arm 67 is attached to the outer end of the operation shaft 65. The left and right clutch arms 67 are respectively attached to the left and right side clutch levers 68 and 69 mounted on the steering handle 43, as shown in FIG. Rope 70,7
Connected by 1.

In the first embodiment in which the side clutches 26 and 27 are provided, the left and right side brakes 28 and 29 described above are installed on the left and right outer surfaces of the mission case 10 as shown in FIG. As shown in FIG. 1 for the brake 29 on one side, each side brake 28, 29 has a brake band 73 along the inner peripheral surface of a brake drum 72 welded and fixed to each axle 13, 14 to rotate the cam shaft 74. It is configured as an inward expansion type brake that obtains braking by expanding the brake band 73 and pressing it against the brake drum 72 by operation. The brake arms 75 attached to the cam shafts 74 of the left and right brakes 28 and 29 are, as shown in FIG.
Are connected to the left and right side clutch levers 68 and 69, and by operating the levers 68 and 69, the side clutches 26 and 27 are first disengaged, and then the side brakes 28 and 29 are operated. .

During operation by the lawn mower shown in FIG. 7, the shift of the key shift type transmission 15 is performed by the main clutch lever 44.
After the tension / clutch 42 is disengaged by the gear shift lever 57, the vehicle speed can be changed to 5 speeds in the forward direction depending on the length and density of the turf, the density of the operator, the preference of the operator, and the like. When the uncut portion is found, the key-shift type transmission 15 can be put in reverse so that the lawn mower can be moved backward to perform the cutting. When the lawnmower is rotated, the side clutch 26 or 27 on the rotating side is disengaged, and when it is desired to perform a relatively sharp curve, the side brake 28 or 29 is further operated. The turning radius at the time of turning can be freely set by adjusting the degree of operation of the brakes 28, 29 with the levers 68, 69. When the lawn mower is to be kept on a sloping ground, locking the side clutch levers 68 and 69 at the braking positions of the left and right side brakes 28 and 29 will prevent the vehicle from moving on its own and require a sudden stop while traveling. In the event that a trouble occurs, the left and right levers 68 and 69 may be simultaneously gripped and the left and right side brakes 28 and 29 may be simultaneously actuated.

8 and 9 show a transmission according to the second embodiment provided with the differential device 30 described above.

As shown in FIG. 8, the differential device 30 is provided with a pair of drive bevel gears 81 on the differential yoke shaft 80 and a pair of driven bevel gears 82 on the left and right axle shafts 13 and 14, respectively, as usual. However, the differential case which is usually provided in the differential device is not provided. That is, the ninth
As clearly shown in the figure, a pair of square slotted holes 83 arranged opposite each other are formed on the inner surface of the hole formed in the center of the boss of the reduction gear 25, and the flat end portions 80 provided at both ends of the differential yoke shaft 80 are formed.
The gear 25 and the differential yoke shaft 80 are integrally rotated by fitting and fixing a into the groove 83 by means such as shrink fitting. The differential yoke shaft 80 is a rectangular portion 80 at the center in the length direction.
b has a circular through hole 80c.
Left and right axles 1 on the bearing sleeve 84 that fits in c
The inner ends of 3, 14 are supported. Drive bevel gear 8
1 and the driven bevel gear 82 are respectively applied to the square portion 80b of the differential yoke shaft 80 via thrust receiving washers 85 and 86.

The traveling brake 31 shown in FIG.
The flat portion 8 at the inner end is formed in the rectangular slot 21a formed in one end surface of
A brake shaft 87 is provided which is fitted with 7a and protrudes to the outer surface of the transmission case 10. The traveling brake 31 has a brake band 89 along the inner peripheral surface of the brake drum 88 welded and fixed to the brake shaft 87, and the brake band 89 is expanded by rotating the cam shaft 90 to expand the brake band 88.
It is configured as an inward expansion type brake that is pressed against and obtains braking.

The other parts of the second embodiment are constructed similarly to the corresponding parts of the first embodiment and are designated by the same reference numerals.
The side clutch 2 provided in the first embodiment can be understood by comparing FIGS. 1 and 8 so that most of the transmission can be shared between the first embodiment and the second embodiment.
6, 27 and the differential device 30 provided in the second embodiment are provided within the same installation width. The square slot 21a on the end face of the intermediate shaft 21 described above with reference to FIG. 8 is also provided in the first embodiment as shown in FIG. 1, and in order to pass the brake groove 87 provided in the second embodiment. Is also provided in the mission case 10 of the first embodiment and is closed by the lid 92 as shown in FIG.

In the transmission according to the second embodiment shown in FIGS. 8 and 9, the vehicle travels when the left and right axles 13, 1 are rotated at the same time.
This is facilitated by the differential device 30 which will provide a rotational speed difference to the gear No. 4. The differential gear 30 that eliminates the differential case by directly supporting the differential yoke shaft 80 that supports the drive bevel gear 81 on the reduction gear 25 that is the differential gear input gear has an extremely compact structure and is intended for a small work vehicle. It is suitable.

Effect of the Invention This invention is applied to a small traveling work vehicle and has a compact structure to reduce the rotation of the transmission shaft 12 of the key shift type transmission device 15 that performs multiple shifts to the left and right axles 13 and 14 by decelerating the rotation of the transmission shaft 12. And a structure in which the transmission shaft 12 is a hollow shaft, and one of the left and right axles 14 is provided so as to penetrate the transmission shaft 12,
Key shift type transmission 15 Structure in which an intermediate shaft 21 arranged substantially concentrically with the drive shaft 11 on the driving side is provided to reduce gears between the transmission shaft 12 and the intermediate shaft 21 and between the intermediate shaft 21 and the axles 13 and 14, respectively. Thus, although the gears are decelerated in two stages on the driven side of the transmission 15, the shaft arrangement width of the plurality of shafts in the transmission case 10 is almost the same as the shaft arrangement width of the transmission having two parallel transmission shafts. Equal to multiple shafts 11, 12, 13, 14, 2
This has the effect of significantly reducing the transmission width in the direction crossing 0, and thus the transmission case width, compared to the conventional case.

[Brief description of drawings]

1 is a cross-sectional plan view showing a first embodiment of a transmission according to the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is a part of FIG. FIG. 4 is an enlarged cross-sectional view in which FIG. 4 is enlarged, FIG. 4 is a perspective view showing one end portion of a hollow transmission shaft provided in the transmission shown in FIGS. 1 and 2, and FIG. 5 is a line V-V in FIG. 6 is an enlarged sectional view taken along
1 is a perspective view showing a part of an operating mechanism of a side clutch provided in the transmission shown in FIGS. 1 and 2, and FIG. 7 is a walk-behind lawnmower equipped with the transmission shown in FIGS. FIG. 8 is a schematic perspective view, FIG. 8 is a cross-sectional plan view showing a second embodiment of the transmission according to the present invention, and FIG. 9 is an exploded perspective view showing a part of the transmission shown in FIG. Is. 10 ... Mission case, 11 ... Drive shaft, 12 ... Shift shaft, 13, 14 ... Axle, 15 ... Key shift type transmission,
16F ₁ , 16F ₂ , 16F ₃ , 16F ₄ , 16F ₅ ... Gear, 16R ... Sprocket gear, 17F ₁ , 17F ₂ , 1
7F ₃ , 17F ₄ , 17F ₅ ... Gear, 17R ... Sprocket gear, 18 ... Long groove, 19 ... Shift key, 20 ... Reduction gear mechanism, 21 ... Intermediate shaft, 22, 23 ... Reduction gear, 24, 25
... Reduction gears, 26, 27 ... Side clutches, 28, 29
... differential device, 30 ... travel brake, 35 ... rear wheel, 36 ...
Engine, 39 ... Input shaft, 47 ... Bevel gear, 48 ... Bevel gear, 54 ... Chain, 55 ... Shifter sleeve, 63 ... Clutch sleeve, 80 ... Differential yoke shaft, 80a ... Flat end portion, 81 ... Drive bevel gear.

Claims (5)

[Scope of utility model registration request] 1. A mission case (10) equipped with a drive shaft (11) and left and right axles (13, 14) concentric with a transmission shaft (12) in parallel with each other, and fixedly installed on the drive shaft (11) in the mission case (10). Gears 16F ₁ , 16F ₂ , 1
6F ₃ , 16F ₄ , 16F ₅ and gears 17F ₁ , 17F ₂ , 17F ₃ , 17F ₄ , 17F ₅ loosely fitted and installed on the transmission shaft 12.
And a plurality of shift gear trains formed by meshing
A key shift type transmission device 15 for performing multi-stage gear shifting by selectively connecting the above gears to the gear shift shaft by a clutch projection 19a of a shift key 19 slidable in a long groove 18 on the outer peripheral surface of the gear shift shaft. In a transmission of a traveling work vehicle, the transmission shaft 12 is formed as a hollow shaft, and a reduction gear mechanism 20 that decelerates and transmits the rotation of the transmission shaft 12 to the left and right axles 13 and 14 in the mission case 10. One of the left and right axles 13 and 14 is provided so as to penetrate the speed change shaft, and the intermediate shaft 2 is arranged substantially concentrically with the drive shaft 11.
1 is provided in the transmission case 10 and the reduction gear mechanism 20 is arranged between the speed change shaft 12 and the intermediate shaft 21 by the first reduction gears 22 and 23 rows, the intermediate shaft 21, and the left and right axles 13 and 1.
A transmission comprising a second reduction gear train 24, 25 arranged between four gears. 2. The transmission according to claim 1 of the utility model registration, wherein the driven-side reduction gear 25 of the second reduction gear train is spread over the left and right axles 13, 14 described above. The left and right side clutches 26, 2 are fitted between the driven-side reduction gear 25 and the left and right axles 13, 14, respectively.
A transmission characterized by having 7 installed. 3. The transmission according to claim 2, wherein the left and right axles 13,
Left and right side brakes 28, 29 for braking 14
Is installed on the outer surface of the mission case 10. 4. The transmission according to claim 1 for utility model registration, wherein a differential device 30 is provided between the left and right axles 13 and 14 in the transmission case 10.
And the driven side reduction gear 25 in the second reduction gear train is configured as an input gear of the differential device 30, and a brake 31 for braking the intermediate shaft 21 is provided on the outer surface of the transmission case 10. A transmission characterized by being installed in. 5. The transmission according to claim 4 of the utility model registration, wherein a differential yoke shaft 80 for supporting a drive bevel gear 81 in the differential device 30 is provided in a hole at the center of the driven side reduction gear 25. Place both ends 80
A transmission which is provided so as to be relatively non-rotatable with respect to the reduction gear 25 at a.