JPS6019535Y2 - Power transmission device for power lawn mower - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a powered lawn mower whose cutting blades are driven and rotated by an internal combustion engine or an electric motor.

Many injuries that occur while using this type of lawn mower are caused by the rotating cutting blade.

As a safety measure, a switch is provided near the bundle that closes as soon as the bundle is grasped, so that the prime mover operates as long as the bundle is held, and stops when the bundle is released.

However, with the above-mentioned safety device, if it is necessary to frequently remove the hand from the nozzle, the engine must be restarted each time if the engine is equipped with an internal combustion engine, and the structure must be such that the engine can be started from the position where the bundle is gripped. This complicates the engine starting system.

In addition, in the case of an electric motor-equipped type, frequent rotation and stopping of the electric motor impairs the durability of the electric motor.

Therefore, the present applicant proposed an easy-to-operate power transmission system with an excellent safety device that instantly stops the cutting blade even if the prime mover is rotating when the bundle is released, as shown in Japanese Patent Application Laid-open No. 54-5483. proposed.

The proposed power transmission device disengages the friction clutch 10, 11 and at the same time operates the cam plate 19 that operates the brake plate 15 that applies a brake to the friction plate 11 on the cutting blade side, and the radial ball bearing 18 on the lower surface of the machine body 1. It is supported by the output shaft 7 via the output shaft 7.

However, since a force acts on the cam plate 19 in the direction of the output shaft, that is, in the thrust direction, when the cam plate 19 is operated, the radial ball bearing 18 cannot completely receive the thrust force, and the radial ball bearing 18
The friction material 17 may wear unevenly due to the inclination of the cam plate 19, the brake plate 15, etc., which may adversely affect its accuracy.

The present invention solves the above problems based on the bearing support structure of the cam plate for the body of the conventional power transmission device of a power lawn mower, improves the accuracy of the clutch and braking mechanism, and prevents failure of the clutch and braking mechanism. The aim is to reduce the occurrence.

In this embodiment, the device of the present invention is applied to a rotary lawn mower, and its configuration will be explained with reference to FIGS. 1 and 2.

A prime mover (not shown) is arranged in the fuselage 1 with an output shaft 2 facing downward.

A cutting blade rotating shaft 4 is attached around the lower end of the output shaft 2 via a bearing 3 to freely rotate, and a cutting blade 5 is fixed to this shaft 4.

Then, one friction plate 6 of the friction clutch is fixed to the output shaft 2, and the other friction plate 7 is attached integrally and movably in the axial direction to the cutting blade rotating shaft 4, and the movable friction plate 7 is pressed against the fixed friction plate 6. A clutch spring 9 is provided which is charged with energy so as to cause the clutch to move.

Reference numeral 10 denotes a friction material stretched over the contact surfaces of both the engaging members 6 and 7.

In order to connect the movable friction plate 7 to the cutting blade rotating shaft 4 so that it can rotate integrally and move in the axial direction, a flange 41 that is integral with the cutting blade rotating shaft 4 is provided.
Several sets of bushes 25, which can be made of hard synthetic resin, and pins 26 that fit into the bushes 25 are provided between the bushings 25 and the peripheral edge of the movable friction plate 7.

The brake plate 11 is suspended from the body 1 so as to be movable up and down by a rubber damper 12, and acts on the movable friction plate 7 to perform braking and at the same time disengage the friction clutch.

A friction material 13 is provided on the surface of the brake plate 11 facing the movable friction plate 7.

A cam plate 14 loosely fitted to the output shaft 2 connects the central cylinder portion 14a to a hole 27 on the lower surface of the body through a thrust ball bearing 15.

The thrust ball bearing 15 has a large number of balls 15a housed in a ring-shaped elastic holding member 8 having a U-shaped cross section, and has a circumferential groove 28 formed around the output shaft 2 on the back of the body.
The elastic holding member 8 is assembled into the structure.

The above-mentioned cam plate 14 has a plurality of circumferential cam grooves 16 on the surface facing the brake plate 11, and a plurality of circumferential cam grooves 16 are engaged between the brake plate 11 and the cam plate 14 for each of the above-mentioned cam grooves 16. ball 17
The retainer 18 holding the retainer 18 is attached so as to be rotatable back and forth in the circumferential direction.

The link 19 is rotatably attached to the lower surface of the fuselage 1 with a bolt 20, one end of which is inserted into a hole 21 in the peripheral vertical wall 14b of the cam plate 14, and the other end is connected to a bundle (not shown) via a flexible wire 22. It is connected to an operator attached near the grip.

The link 19 is also provided with a spring 23 that applies a rotational force in the opposite direction to that provided by the flexible wire 22, and this spring 23 is stronger than the clutch spring 9 described above.

These are links 19, mounting bolts 20, and flexible wires 22.
The operating mechanism for the cam plate 14 is configured by the above.

When the prime mover is started and the cam plate 14 is encircled clockwise in FIG. 2 via the flexible wire 22 and link 19 using the operator on the bundle grip part, as shown in FIGS. 1 and 3 a. The ball 17 is moved to the deepest position of the cam groove 16.

Therefore, the movable friction plate 7 is pushed up by the force of the clutch spring 9 and comes into pressure contact with the fixed friction plate 6.

That is, the rotation of the output shaft 2 is transmitted to the cutting blade 5 by connecting the friction clutches 6 and 7.

In this state, the machine is run to mow the lawn.

When the tensile force of the flexible wire 22 in the direction of the arrow in FIG. be returned.

Therefore, the ball 17 moves to the shallowest position of the cam groove 16 as shown in FIGS. 3b and 4.

Since the balls 17 are pushed down by the cam grooves 16 due to the wedge action, the brake plate 11 is pushed down against the rubber damper 12 and presses against the movable friction plate 7 to perform braking, and at the same time is also moved against the clutch spring 9. Push down the dynamic friction plate 7 and separate it from the fixed side friction plate 6.

That is, the friction clutches 6 and 7 are disengaged, and the cutting blade stops while the output shaft 2 continues to rotate.

As a result, even if the prime mover is started, the cutting blade 5 will not rotate unless the flexible wire 22 is pulled.

When the tensile force of the flexible wire 22 is released during lawn mowing work, the cutting blade 5 is braked and immediately stops, so it is safe.

Furthermore, since the prime mover continues to rotate even when the cutting blade 5 stops, there is no need to perform a starting operation each time work is resumed, making operation easier.

As described above, since the device of the present invention connects the cam plate 14 to the fuselage via the thrust ball bearing 15,
A radial ball bearing (Japanese Patent Application Laid-Open No. 1989-1996) is installed between the output shaft 2 and the cam plate 14 to receive the thrust load of the clutches 6 and 7.
- The disadvantage of providing the bearing 18) described in Publication No. 54832, namely, the inclination of the brake plate 11 and the cam plate 14 due to the backlash of the radial ball bearing, which adversely affects the wear and accuracy of the friction material 13, can be effectively eliminated. .

As a result, failures are reduced.

In addition, as shown in the illustrated example, the movement of the flexible wire 22 is linked to the link 19.
If the information is transmitted to the cam plate 14 via the link 19
Distance A from the center of rotation to the point of action on the cam plate 14
According to the length of the distance B from the rotation center to the attachment point of the flexible wire 22 and the direction of the pulling force of the flexible wire 22, the pulling load of the flexible wire 22, that is, the clutch operation load of the operator can be reduced. .

Further, if the braking plate 11 is made to directly act on the movable friction plate 7 of one of the friction clutches 6 and 7 to simultaneously perform braking and clutch release as shown in the illustrated example, the number of parts and weight can be reduced. can.

The present invention is not limited to the power transmission device for a power lawn mower as shown in the drawings, and is not limited to the power transmission device of the power lawn mower as shown in the figure.
In the power transmission device shown in Japanese Patent No. 54832, the same effects as described above can be obtained by removing the radial ball bearing and connecting the cam plate to the i-body through a thrust ball bearing.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view of the power transmission device of the present invention with the clutch connected, Fig. 2 is a cross-sectional view taken along the line ■-■ in Fig. 1, Fig. 3 is an explanatory diagram of the operation of the ball cage, and Fig. The figure is a longitudinal sectional front view of a portion of the power transmission device of the present invention with the clutch disengaged. 1 is a machine body, 2 is an output shaft, 3 is a bearing, 4 is a cutting blade rotating shaft, 5 is a cutting blade, 6 and 7 are friction plates constituting a friction clutch, 8 is a ring-shaped elastic holding member, 9 is a clutch spring, 10
・13 is a friction material, 11 is a brake plate, 12 is a rubber damper, 1
4 is a cam plate, 15 is a thrust ball, 16 is a cam groove, 1
7 is a ball, 18 is a retainer, 19 is a link, 22 is a flexible wire, and 23 is a spring.

Claims (1)

[Scope of utility model registration request] A prime mover is placed on the machine body with the output shaft facing downward, a cutting blade rotating shaft is attached freely to the lower end of the output shaft, one friction plate is attached to the output shaft, and the other friction plate is attached to the output shaft. A pair of friction plate clutches are attached to the mower blade rotating shaft so as to rotate integrally and move in the axial direction, a clutch spring is pressed against the movable friction plate so as to engage the pair of friction plate clutches, and a clutch spring is attached to the movable friction plate so as to move vertically relative to the machine body. a cam plate provided between the above-mentioned body and the brake plate, a plurality of circumferential cam grooves provided on the surface of the cam plate facing the above-mentioned brake plate, and each of the circumferential directions. a retainer having a plurality of protrusions that engage with the cam groove; a cam plate operating mechanism that operates the cam plate;
A power transmission device for a power lawn mower, in which the cam plate described above is connected to the machine body via a thrust ball bearing.