JPH045795Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a speed changing device suitable for use in small and simple operations such as a power lawn mower.

(Prior Art) A small power lawn mower moves on wheels and mowing the lawn by rotating a cutter on the underside of the machine, and the cutter and wheels are driven by engine power. Since the working speed of such a lawn mower is slow, it is convenient to move the lawn mower forward and backward at the same time as mowing the lawn mower continuously without having to change direction.

(Technical problem to be solved by the invention) In order to selectively switch between forward and backward movement, a transmission is required, and small working machines such as lawn mowers have a simple structure, are small, and are inexpensive. Preferably. Therefore, a pair of driven friction disks are provided on the output shaft to the wheels, and a driving friction roller is provided between them, and one of the disks is engaged with the roller to achieve forward rotation, while the other disk and roller are engaged with each other. It is possible to switch between forward and backward movement by rotating in the opposite direction after engagement, thereby simplifying the structure, downsizing, and reducing costs.

By the way, switching of the above-mentioned transmission is conventionally done by placing two friction disks on a shaft and swinging a roller between the disks and bringing one of the friction disks into contact with the roller. Since it rotates, its rocking engagement/disengagement mechanism is complicated, and therefore the switching (mechanism) structure is required to be simple, and its operation to be reliable and smooth.

The present invention has been made to solve the above technical problems, and its purpose is to provide a switching device for a transmission that can simplify the structure and ensure smooth and reliable operation. It is in.

(Means for Solving the Technical Problems) In order to solve the above problems, the present invention provides a pair of friction disks on a shaft that rotate integrally with the friction disks, and selectively engages one of the friction disks. In a transmission device having a friction roller between the disks driven by an output from the engine, the position of the friction roller is fixed between the friction disks, and the shaft is attached to the friction disk. A cylindrical boss portion that is movably fitted only in the axial direction is provided respectively, and a spring around the shaft is interposed between the friction disks. Each guide element is provided with a guide element that moves independently in the direction of engagement with the friction roller.
The present invention is characterized in that a swing mechanism is provided for independently sliding each of the guides in the axial direction.

(Operation by the above means) According to the above means, the friction roller is fixed, and the friction disks disposed on both sides of the friction roller are independently moved to engage with and disengage from the roller. The shaft sliding mechanism is simple, and the swinging mechanism that slides it can also be composed of a lever mechanism, etc., and the structure is simple, and switching is possible because the two disks, forward and reverse, are selectively engaged with the rollers. It is reliable and allows smooth switching.

By interposing a spring between the disks, in response to the independent engagement operation of one disk with the roller, the other disk can be reliably disengaged from the roller. There is no need to provide a coupling mechanism for this purpose.

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

Figure 1 shows a lawn mower as an example of workability.
The subject of implementation is not limited to this and is arbitrary.

The lawn mower 1 is equipped with two front wheels 3, which are rollers, on the left and right sides of the front of the machine body 2, and two rear wheels 4, which are drive wheels, on the left and right rear parts, and an engine 5 on the machine body 2.
Also, a handle 6 is provided at the rear so as to be inclined rearward and upward.

The fuselage 2 consists of a frame 7 and a housing 8, as shown in FIGS. 4 and 5, and an engine 5 is mounted on the frame 7. The engine is a vertical engine with a vertical crankshaft, and a clutch mechanism 9 is attached to the lower end of an output shaft 501. A vertical cutter drive shaft 101 is fixedly fixed to the outer 902 below, and the lower half of the shaft 101 extends downward from the boss portion 702 of the container-shaped main body 701 of the frame 7. The cutter 10 is fixed to the lower end, and the main body 701 is surrounded by a bowl-shaped middle part 801 of the housing 8.

The front wheels 3, 3 are supported by a support rod 1 that is placed horizontally on two arms 703, 703 provided at the front of the frame 7.
The rear wheels 4, 4 are supported via the stays 12, 12 at both ends of the frame 7, and the bases 131, 14 are supported by two arms 704, 705 provided on the rear left and right sides of the frame 7.
1 is connected to reduction cases 13 and 14 via support shafts 401 and 401.

Between the base parts 131 and 141 which are the upper parts of the reduction cases 13 and 14, an intermediate transmission shaft 15 serving as a drive shaft is horizontally mounted, and both ends of the intermediate transmission shaft 15 are rotatably supported by bearings 16.
The final drive shaft 18 is supported horizontally between the boss portions 132 and 142 at the intermediate portions of the reduction cases 13 and 14, and one end portion 151 is extended and the sprocket 17 is fixed thereto. is rotatably supported by a bearing 19, and a pinion 20 is fixed to each end of the shaft and meshed with internal gears 402, 402 provided on the inner surfaces of the rear wheels 4, 4. When the shaft 18 rotates, the pinion 20 rotates the rear wheel. 4, 4 are rotationally driven, and the shaft 18 passes through a cylindrical holding member 21 that is horizontally fixed between the opposing inner end surfaces of the boss portions 132 and 142. A sprocket 22 is fixedly installed in front of the pinion 20 at one end 181 of the shaft 18, and this is connected to the sprocket 17 via a chain 23, so that the shaft 1
The output of 5 is transmitted to shaft 18.

A pair of friction disks 2 are provided on the shaft 15 at an intermediate portion thereof, spaced apart in the axial direction, that is, in the left-right direction.
4 and 25 are provided, and a friction roller 26 is provided between the friction portions 241 and 251 on the inner surface of the peripheral portion of the friction disk. The friction roller 26 is equipped with a large-diameter pulley portion 261 at the bottom, and the drive pulley 27 is installed on the output shaft 501 described above, which are connected by a belt 28 to transmit the engine output to the roller 26. The belt 28 is connected to and disconnected from the roller by tightening and loosening the belt 28 by a clutch roller 29. It is rotatably supported by a shaft 262.

The friction disks 24 and 25 have a disk shape with a middle portion bulging outward in the axial direction, and have cylindrical boss portions 243 and 253 at the center of the middle portions 242 and 252, respectively. 243, 253 and intermediate portions 242, 252 are integrally joined. Each of the boss portions 243, 253 is fitted to the shaft 15 so as to be integral with the shaft 15 in the rotational direction but slidable in the axial direction.
5. The bearings 16, 16 and the boss portion 243 at both ends,
Collar-shaped stoppers 30, 30 are provided between the outer ends of the disks 253, and when the inner ends of the stoppers 30 are in contact with the rear end of the boss, the disks 24, 25 are opened between the rollers 26. It becomes a detached state. Boss part 2
A return spring 31 made of a coil spring is interposed around the shaft 15 between the opposing inner ends of the shafts 43 and 253, and the spring 31 separates the boss portions 243 and 253 and therefore the friction disks 24 and 25 from each other. roller 2
The spring 3 which is elastically biased in the direction of separating from the spring 6
One circumference is covered with a bellows-shaped dust boot 32.

Annular locking protrusions 244, 254 are provided on the axially outer periphery of the boss portions 243, 253, and annular guide members 33, 33 are provided on the axially outer periphery of the boss portions 243, 253 as shown in the third figure.
are slidably fitted to each other, and a holder 331 is fixed to the outer periphery of each guide 33. both sides of the holder 331,
In the embodiment, pin-shaped protrusions 332, 332 are provided at the front and rear, and the protrusions 332, 332 are connected to collars 333, 3.
33 to the bifurcated locking portion 342 of the swinging lever 341 of the swinging mechanism 34, and the swinging lever 341
As shown in FIG. 3, it is configured to sandwich both sides of the holder 331 including the guide 33, and in the embodiment, it is formed of two symmetrical members 343 and 344, and a bifurcated locking portion 342 is provided at the tip of each member. It is formed. The bases of the members 343 and 344 are rotatably supported on a support shaft 347 via a cylindrical boss member 345 and a bearing collar 346, and an extension portion extends outward in the axial direction of the shaft 15 at right angles from the base. 348 is provided with an operation input member 349, which is connected to the cutting lever of the handle 6 with, for example, a cable 35.
Both 3 and 253 have the same structure, and the lever 341 is the second
As shown in the figure, it has an L-shape when viewed from the front, and each lever has a symmetrical shape. The shaft 347 is the left and right reduction case 1
Boss part 13 provided near the base of parts 3 and 14
3 and 143 through bolts 134 and 144.

In addition, (36) in Figure 5 is the dust cover, 37, 38
is a swingable door plate that closes the front and rear openings 802 and 803 of the housing 8.

In the above, on the other hand, for example, when the lever 341 of the swinging mechanism 34 on the left side A in FIG. The holder 331 moves to the right in the figure with respect to the spring 31 via the protrusion 332 that is engaged with the protrusion 332 . As a result, the friction disk 24 on this side moves to the right, and the roller 26
The power of the roller 26 is transmitted to the shaft 15, and rotates forward, for example, to move the rear wheels 4, 4 forward. On the other hand, the other friction disk 25 is urged in the opposite direction by the spring 31 and separated from the roller 26, and the outer end of the boss portion 253 is in contact with the stopper 30, so that a predetermined clearance is maintained between the roller 26 and the disk 25. Ru. This is shown in Figure 2.

By compressing the cable 35 on the left side, the spring 3
1, the disk 24 slides on the shaft 15 in the opening direction, and by similarly swinging the lever 34 on the right side, that is, the B side, by the pulling motion of the cable 35, the boss member 253 slides on the shaft 15 to the left. The disc 25 frictionally engages with the roller 26, causing the shaft 15 to rotate in the opposite direction, thereby performing a backward movement.

(Effect of the invention) As is clear from the above, according to the invention, two friction disks can be slid independently on the shaft without moving the friction roller side, and one disk can be attached to the roller. Because the mechanism is selectively engaged to switch between forward and backward movement, the mechanism is simpler than a mechanism in which a rotatably driven roller is swung to press and engage one of the two disks. Because it is a mechanism that slides on a shaft, a guide, a lever that slides it, etc. are sufficient, so the structure is simple, and a forward/backward switching device can be obtained simply.
Moreover, it can be provided at low cost.

Secondly, since the disks slide independently on the shaft, the mechanism is compact, which is advantageous when installed in the restricted space of small working machines, and the two disks can be moved individually to the rollers. Since the discs are engaged by sliding on the shaft, the operation is reliable, and a spring is interposed between the discs to ensure reliable separation.For example, there is no need to provide a coupling mechanism for forward/reverse switching at the shaft end. The spring and the opening mechanism, which are interposed around the shaft, are simple and sufficient.

The present invention has many advantages as mentioned above.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic side view of a lawn mower as an example of a working machine, FIG.
3-3 is an enlarged cross-sectional view, FIG. 4 is a cross-sectional plan view, and FIG. 5 is a vertical cross-sectional side view. In the drawing, 15 is a shaft, 24 and 25 are friction disks, 243 and 253 are boss parts, 26 is a friction roller, 33 is a guide, and 34 is a swing mechanism.

Claims (1)

[Claims for Utility Model Registration] A friction roller that is provided with a pair of friction disks that rotate integrally on a shaft, selectively engages with one of the friction disks, and is driven by the output of the engine. In the transmission device, the friction roller is fixed in position between the friction disks, and a cylindrical boss portion is fitted to the friction disk so as to be movable only in the axial direction with respect to the shaft. a spring around the shaft is interposed between the friction disks, and the cylindrical boss portion allows each of the friction disks to move independently in a direction of engagement with the friction roller. A switching device for a transmission, characterized in that guide elements are provided, and a swing mechanism that independently slides each of the guide elements in an axial direction is provided.