JPH0620932Y2 - Key shift type transmission - Google Patents

Description

TECHNICAL FIELD The present invention relates to a key-shift transmission that is suitable for vehicle speed control of a relatively small self-propelled work vehicle such as a self-propelled walking lawn mower or a mower tractor. Is.

2. Description of the Related Art As disclosed in, for example, U.S. Pat. No. 3,812,735 and well known, a key shift type transmission device relatively slides a plurality of shift gears loosely fitted on a shift shaft to a shifter sleeve slidable on the shift shaft. The shift key is supported immovably and provided along the length direction of the speed change shaft to selectively connect to the speed change shaft to obtain the speed change rotation of the speed change shaft. It is suitable for small traveling work vehicles.

By the way, in the conventional key shift transmission, as disclosed in the above-mentioned U.S. Patents, long grooves corresponding to the number of shift keys are formed on the outer peripheral surface of the shift shaft along the length direction of the shift shaft. The shift key has been installed in.

Therefore, conventionally, a gear shaft having a large outer diameter is used because the above-mentioned long groove is provided as a recess, and the long groove is formed by broaching a shaft material having such an outer diameter.

Problems to be Solved by the Invention A transmission shaft having a large outer diameter has a large weight and is disadvantageous in transmission, and the shaft material is expensive, and the manufacturing cost is further increased due to the shaft processing for forming the long groove.

Therefore, the present invention provides a key-shift type transmission that is provided with a transmission shaft that has a reduced outer diameter compared with a conventional transmission shaft and that requires little shaft machining. Therefore, the above problems are to be solved.

Technical Means for Solving the Problems Therefore, the present invention, as illustrated in FIG.
A plurality of speed change gears 11F ₁ and 11F loosely fitted on
₂ , 11F ₃ , 11F ₄ , 11F ₅ are selectively shifted by a shift key 13 provided along a shift shaft length direction with a shifter sleeve 12 slidable on the shift shaft supported in a non-sliding manner. The following technical means have been taken in the key shift type transmission which is connected to the shaft 10 to obtain the variable speed rotation of the speed change shaft 10.

That is, as illustrated in FIGS. 1 and 6, respectively,
A pair of rails 14a extending along the outer circumferential surface of the speed change shaft 10 and a substantially U-shaped portion extending outwardly in the radial direction of the speed change shaft from both ends of the arcuate portion so as to be opposed to each other in the circumferential direction of the speed change shaft. A plurality of plate-shaped rail members 14 having 14b,
The gears are mounted on the outer peripheral surface of the transmission shaft 10 with a space therebetween in the circumferential direction of the transmission shaft, and the transmission gears 11F ₁ ,
11F ₂ , 11F ₃ , 11F ₄ , 11F ₅ and the shifter sleeve 12 were supported, and the shift key 13 was installed between the rail members 14.

The reference numeral 15 in FIG. 2 is provided on the transmission shaft 10 between the rail members 14.
A long groove is formed, that is, a long groove having the outer peripheral surface of the speed change shaft 10 as the inner bottom surface and the outer side surfaces of the rail portions 14b of the adjacent rail members 14 respectively as the inner side surfaces. Since it is arranged, the shift key 13 cannot rotate relative to the transmission shaft 10.

Were it similarly to the conventional shift key by connexion the shift key 13 may shift gear 11F ₁ -11F ₂ non-rotatably coupled to the speed-change shaft 10.

In the illustrated example, each rail member 14 is shifted by a screw bolt 17 (Figs. 1 and 6) that is inserted through a hole 16 (Fig. 4) formed in the arc portion 14a and screwed into a screw hole of the transmission shaft 10. Axis 10
However, the rail member 14 can be attached to the transmission shaft 10 by welding.

The illustrated embodiment is an example in which the present invention is implemented as a transmission for a self-propelled traveling lawn mower. A key shift type transmission is a mission case mounted on a machine frame between left and right drive wheels of the lawn mower. The transmission shaft 10 is installed in a wheel axle 18 and extends leftward and rightward from the transmission case 18 to form a wheel axle.

As shown in FIG. 3, a vertical input shaft 19 extending over the inside and outside of the motion case 18 is provided on the top wall of the motion case 18.
The drive shaft 22 to which the large bevel gear 21 meshed with the small bevel gear 20 of the input shaft 19 is fixed is arranged in parallel with the transmission shaft 10 as shown in FIG. It is provided in. The transmission shaft 1 is mounted on the drive shaft 22.
Drive gears 23F ₁ , 23F ₂ , 23 meshed with the transmission gears 11F ₁ + 11F _{5 on}
F ₃ , 23F ₄ , and 23F ₅ are fixedly installed in contact with each other.

The three rail members 14 provided in the embodiment of FIG. 1-5 are made of sheet metal as shown in FIG. 4, and in addition to the holes 16 described above, at the projecting end of each rail portion 14b. It has two notches 24 facing each other. This notch 24, as shown in FIG. 2, the speed change gear _11F 1 -1
1F in ₅ groups of one wearing the elastic stop 25 which forms a circular arc shape are to regulate the axial displacement of the transmission gear _11F 1 -11F _5. Three elastic stoppers 25 are provided in an arrangement in which the snap ring is divided into three.

The shift key 13 is provided at the base end thereof with the shifter sleeve 1
It is connected to the shifter sleeve 12 in a non-sliding manner by holding 2 and has a clutch projection 13a at its tip as usual. A leaf spring 26 is attached to each shift key 13 at the base end thereof.
The shift key 13 from the inner bottom side of the key
The clutch projection 13a is urged to be displaced in a direction in which the clutch projection 13a projects outward from the inside of the long groove 15. Each transmission gear _11F 1 -11
The inner circumferential surface of the F _5, clutch projection 13a is is formed a slot 27 which can plunge.

In order to selectively shift the shifter sleeve 12 on the speed change shaft 10, a shifter fork 29 whose operation end is projected to the outside of the upper surface of the mission case 18 is attached to the shifter sleeve 12 as shown in FIG. It is provided so as to engage with each other. This shifter fork 29 is formed by punching out a sheet metal as shown in FIG. 5, and the cylinders 30, 31 having holes 30a, 31a of corresponding cross-sections at both ends are externally inserted, and the cylinder 30, It is supposed that the 31st part provides a rotatable support. As shown in FIG. 3, the upper cylinder 30 is integrally formed with an arm 32 for rotating the shifter fork 29. Cylinder 30,3
1 is supported by a guide cylinder 33 provided upright in the case 18, and the guide cylinder 33 is provided with a notch 33a for projecting a fork portion of the shifter fork 29.

As shown in FIG. 3, the transmission shaft 10 and the drive shaft 22 are
As shown in FIG. 2, bearing sleeves 35 and 36 supporting both ends of the shafts 10 and 22 are sandwiched and supported by two upper and lower sheet metal bearing frame plates 37 and 38, respectively. By placing the upper case halves made of plastic on the welded upper and lower bearing frame plates 37, 38 and tightening both the case halves and the bearing frame plates 37, 38 together, a shift case is formed. 18 are configured.

For shifting operation, a shift lever (not shown) rotates the shifter fork 29 through the arm 32, whereby the shift shaft 1
It is said that the shift key 13 is slidably displaced on the zero position to obtain the shift of the shift key 13 in the long groove 15 and then performed. Shift key 13 by the clutch projection 13a rushes into the slot 27 of the speed change gear _11F 1 -11F _5, binds selectively to the transmission shaft 10 destined one speed change gear _11F 1 -11F _5.

FIG. 6 relates to an example in which two rail members 14 are provided corresponding to the provision of two shift keys 13. The number of slots 27 on the inner peripheral surface of the transmission gear is also two, corresponding to the number of keys 13.

Advantageous Effects of Invention The present invention attaches a plurality of plate-shaped rail members 14 having the above-described shapes to the outer peripheral surface of the speed change shaft 10 at intervals in the circumferential direction of the speed change shaft, and forms a long groove between adjacent rail members 14. since it was decided to support the transmission gear _11F 1 -11F ₅ and shifter sleeve 12 a shift key 13 installed on the rail member 14 in a 15, a transmission shaft 10 and each compared with the conventional small diameter shaft, the rail member 14 Since it is used after only a slight modification for mounting, it greatly contributes to the cost reduction of the key shift type transmission while reducing the weight of the transmission shaft.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an essential part of an embodiment of the present invention, and FIG. 2 is a cross-sectional plan view of a mesh case incorporating the same embodiment (the cross-section of the portion shown in FIG. 1 is shown in FIG. II-II
Follow the line. ), FIG. 3 is a partially omitted cross-sectional view substantially along the line III-III in FIG. 2, FIG. 4 is a perspective view showing a part of the above embodiment, and FIG. FIG. 6 is a perspective view showing a part of FIG. 1 in a disassembled state, and FIG. 6 is a cross-sectional view similar to FIG. 1, showing a main part of another embodiment. 10 ... gear shift shaft, 11F ₁ , 11F ₂ , 11F ₃ , 11
F _4, 11F ₅ ...... transmission gear, 12 ...... shifter sleeve 13 ...... shift key 14 ...... rail member, 14a
...... Arc part, 14b ...... Rail part, 15 ...... long groove, 16
...... Hole, 17 ...... Screw bolt, 22 ...... Drive shaft, 23F
₁ , 23F ₂ , 23F ₃ , 23F ₄ , 23F ₅ ... Drive gear.

Claims (1)

[Scope of utility model registration request] 1. A shift key provided with a plurality of speed change gears loosely fitted on the speed change shaft supported by a shifter sleeve slidable on the speed change shaft so as not to be slidable relative to each other, and provided along the length direction of the speed change shaft. In the key shift type transmission which is selectively coupled to the speed change shaft to obtain the speed change rotation of the speed change shaft, an arcuate portion 14a along the outer peripheral surface of the speed change shaft 10 and substantially U-shaped portions from both side ends of the arcuate portion are formed. A plurality of plate-shaped rail members 14 each having a pair of rail portions 14b that project outward in the radial direction of the speed change shaft and that have their projecting ends facing each other in the circumferential direction of the speed change shaft
The gears are mounted on the outer peripheral surface of the transmission shaft 10 with a space therebetween in the circumferential direction of the transmission shaft, and the transmission gears 11F ₁ ,
A key-shift type transmission, wherein 11F ₂ , 11F ₃ , 11F ₄ , 11F ₅ and the shifter sleeve 12 are supported, and the shift key 13 is installed between the rail members 14.