JPH0441801Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to an improvement of a power transmission device for a mower.

(b) Conventional technology In general, a lawn mower uses an engine mounted on a casing as a driving source to mowing the grass by rotating a blade, which is a rotary blade, while running on its own using an engine mounted on a casing. is transmitted to the driving wheels via the power transmission device, and the driving wheels are rotationally driven.

By the way, the above-mentioned power transmission device has a drive shaft end facing inside a drive wheel that is rotatably supported by an axle fixed to the main body side, and a pinion gear provided at the drive shaft end that rotates. It is known that the drive wheel is rotationally driven by rotating an internal gear of the drive wheel that meshes with the drive wheel.
In this type of power transmission device, the connection between the drive shaft and the pinion gear is achieved by a so-called dog clutch using an internally expanding pawl cam or the like (see, for example, Japanese Utility Model Application No. 55-47439).

(c) Problems to be solved by the invention However, in the conventional power transmission device mentioned above, parts such as the claws of the dog clutch are small, and it is necessary to maintain high machining accuracy of these parts, resulting in high machining costs. If the pressure becomes high and foreign matter such as dust, mud, water, etc. enters the dog clutch, there is a risk that the dog clutch will not operate. In addition, when using this kind of dog clutch, the machine suddenly starts when started, resulting in a large impact, poor operability, and the drive wheels damage the grass, as well as having multiple structures. There was a problem.

The present invention was developed in view of the above-mentioned problems, and its purpose is to create a grass mower with a simple structure that can transmit power smoothly and reliably, suppress sudden starts of the machine, and alleviate the shock at startup. To provide power transmission devices.

(d) Means for Solving the Problems In order to achieve the above object, the present invention has a drive shaft end facing inside a drive wheel which is rotatably supported by an axle fixed to the main body side. A power transmission device for a lawn mower that rotates a pinion gear provided at an end of a drive shaft to rotate an internal gear of a drive wheel that meshes with the pinion gear, thereby rotationally driving the drive wheel. A boss member was loosely fitted onto the drive shaft, and a boss member was tied to the drive shaft, and a coil spring was externally installed between the inner diameter portions of the pinion gear and the boss member.

(E) Effect The boss member rotates together with the drive shaft, and when the coil spring is twisted in the winding direction by the frictional force generated between the boss member and the coil spring, the coil spring The diameter is reduced and the pinion gear is brought into close contact with the outer peripheries of the inner diameter portions of the boss member and the pinion gear to connect the boss member and the pinion gear, thereby rotationally driving the pinion gear. The rotation of the pinion gear drives the internal gear of the drive wheel that meshes with the pinion gear, and finally the drive wheel is rotationally driven and the aircraft travels. During this process of power transmission, the coil spring is torsionally deformed and exerts a buffering effect, resulting in smooth power transmission, preventing the aircraft from starting suddenly during startup, and improving operability. Further, since the above effects can be obtained simply by providing a coil spring, the structure of the device can be simplified and the operation can be ensured. If the drive shaft is reversed, the coil spring is twisted in the counter-winding direction and expands in diameter, so the pinion gear and boss member are not connected, so power is not transmitted and the drive wheel is not rotationally driven. . In this sense, the coil spring functions as a one-way clutch.

(f) Embodiment An embodiment of the present invention will be described below based on the attached drawings.

First, the overall structure of a lawn mower equipped with a power transmission device according to the present invention will be explained based on FIG. 2. In the figure, 1 is a casing, and front wheels 2, Accordingly, both left and right sides of the rear portion are supported by rear wheels 3, 3, which are driving wheels. Note that the vertical positions of the front wheels 2, 2 and the rear wheels 3, 3 relative to the casing 1 are adjusted by rotating the respective levers 4, 4, so that the casing 1
The height of the cutter is adjusted to adjust the cutting height.

Further, an engine 5 serving as a driving source is mounted approximately in the center of the casing 1.
A bag-shaped catcher 6 for storing cut grass stalks is attached to the rear of the machine. Further, a control handle 7 extends diagonally rearward and upward from the upper rear end of the casing 1, and an operation part 7a is provided at the end of the control handle 7 to operate the aircraft with the operator's hand. There is.

By the way, a part of the output of the engine 5 is transmitted to the rear wheels 3, 3, which are driving wheels, through a power transmission device, and these driving wheels 3, 3 are rotationally driven and the aircraft moves by itself. Figure 1 shows details of the three-part power transmission structure. That is, FIG. 1 is a longitudinal sectional view showing the lower half of one rear wheel 3, and as shown in the figure, the rear wheel 3 has an axle which is fixed and protrudes horizontally from the side of the casing 1 (in the vehicle width direction). 8 via ball bearings 9, 9 to be rotatable. The rear wheel 3 is composed of a rim 10 fixed to the outer ring of ball bearings 9, 9, a rubber tire 11 covering the outer periphery of the rim 10, and a wheel cap 26. An internal gear 12 is carved around the entire circumference. The inner side of the rear wheel 3 is positioned by a distance piece 13, and is closed by a disc-shaped wheel cover 14 loosely fitted around the outer circumference of the axle 8.
A space S is formed inside the rear wheel 3.
The rear wheel 3 is prevented from coming off by a liner 15 fixed to the end of the axle 8 with a nut.

On the other hand, below the axle 8 in FIG.
In parallel with this, the drive shaft 16 is connected to a ball bearing 17.
A pinion gear 18 is loosely fitted to the outer periphery of the end of the drive shaft 16 facing into the space S of the rear wheel 3 so as to be freely rotatable. It meshes with the internal gear 12 provided on the rim 10 of the rear wheel 3.
The pinion gear 18 is prevented from coming off the drive shaft 16 by a liner 20 that is fastened to the end of the drive shaft 16 with a nut 19. Further, a boss member 21 is fitted to the outer periphery of the drive shaft 16 inside the pinion gear 18, and the boss member 21 is fitted with a collar 22 and a liner 2 that are inserted into the drive shaft 16.
3, and is connected by a parallel pin 24 passed through the drive shaft 16 so as to rotate together with the drive shaft 16. And this boss member 2
The outer periphery of the wheel cover 14 is loosely fitted into a circular hole 14a formed in the wheel cover 14, and the boss member 21 is rotatably supported by the circular hole 14a. The boss member 21 and the pinion gear 18 are arranged on the drive shaft 16 with a predetermined distance apart.

A coil spring 25 having a rectangular cross section is installed externally between the outer peripheries of the inner diameter part 18a of the pinion gear 18 and the inner diameter part 21a of the boss member 21, which face each other. 18a and the outer diameter of the boss member inner diameter portion 21a.

The drive shaft 16 is connected to the output shaft of the engine 5 via a power transmission member such as a pulley or a drive belt (not shown). Further, in the above explanation, the power transmission structure of one rear wheel 3 portion was explained, but since the other one is also completely the same as above, illustration and explanation thereof will be omitted.

Next, the operation of this power transmission device will be explained.

When the engine 5 is driven, part of its output is transmitted to the drive shaft 16 via a power transmission path (not shown), and the drive shaft 16 is rotationally driven. When the drive shaft 16 rotates, the boss member 21 connected to the drive shaft 16 also rotates, and the boss member 21
The friction force generated between the coil spring 25 and the coil spring 25 twists the coil spring 25 in the winding direction. When this coil spring 25 is twisted, it reduces in diameter and comes into close contact with the outer periphery of each inner diameter portion 21a, 18a of the boss member 21 and pinion gear 18. As a result, the boss member 21 and pinion gear 18
are connected, and the pinion gear 18 is rotationally driven. When the pinion gear 18 rotates, the internal gear 1 provided on the rear wheel 3 that meshes with the pinion gear 18 rotates.
2 is driven, and finally the drive wheels 3 are rotationally driven and the aircraft moves on its own. Although the drive path of one drive wheel 3 has been described above, the drive path of the other drive wheel 3 is exactly the same.

In the above power transmission process, the coil spring 25 is torsionally deformed and exerts a buffering effect, so that smooth power transmission is achieved, preventing sudden start-up of the aircraft at the time of startup, improving operability, and improving maneuverability. ring 3,
The problem that the grass is damaged by 3 is solved. Also, coil spring 2, which is a simple part,
Since the above effects can be obtained simply by providing 5, the structure of the device can be simplified and the operation can be ensured. Note that when the drive shaft 16 is reversed, the coil spring 25 is twisted in the counter-winding direction and expands in diameter.
The opinion gear 18 and the boss member 21 are not connected, so power is not transmitted to the rear wheels 3, 3.
The drive wheels 3, 3 are not rotationally driven. In this sense, the coil spring 25 is a so-called one-way spring.
Functions as a clutch.

(g) Effects of the invention As is clear from the above explanation, according to the invention, the pinion gear 18 is loosely fitted to the drive shaft 16, and the boss member 21 is tied to the drive shaft 16, so that the pinion gear 18 and the boss member Since a coil spring 25 is installed externally on the inner diameter portion 18a, 21a of each of the coil springs 21, the coil spring 25 functions as a so-called one-way clutch, and also torsionally deforms during power transmission to exert a buffering effect.
Smooth power transmission is achieved, the sudden start of the aircraft at startup is prevented, and operability is improved, and the problem of damage to grass etc. caused by the drive wheels 3, 3 is eliminated. can get. Further, according to the present invention, the above effects can be obtained by simply providing the coil spring 25, which is a simple component, so that the structure of the device can be simplified and the operation can be ensured.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view of the lower half of the rear wheel showing a power transmission device according to the present invention, and FIG. 2 is an overall side view of the mower. 3... Drive wheel, 8... Axle, 12... Internal gear, 16... Drive shaft, 18... Pinion gear, 18a... Pinion gear inner diameter part, 21... Boss member, 21a... Boss member inner diameter part, 25...Coil spring.

Claims (1)

[Scope of utility model registration request] The end of the drive shaft 16 faces inside the drive wheel 3 which is rotatably supported by an axle 8 fixed to the main body side,
A mower power transmission in which the drive wheel 3 is rotationally driven by rotating the pinion gear 18 provided at the end of the drive shaft 16 to rotate the internal gear 12 of the drive wheel 3 that meshes with the pinion gear 18. In the device, the pinion gear 18 is connected to the drive shaft 16.
A boss member 21 is loosely fitted to the outer periphery of the end of the pinion gear 18 on the drive shaft 16 so that the pinion gear 18 can rotate freely, and a boss member 21 is attached to the inner side of the pinion gear 18 on the drive shaft 16. A power transmission device for a lawn mower, characterized in that a coil spring 25 is mounted on the exterior.