JP3382400B2 - Engine braking device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking device for an engine mounted on a power working machine such as a power lawn mower, and more particularly, a brake shoe is mounted on a crankcase which supports a crankshaft having a flywheel fixed to one end thereof. A brake spring, which is swingably supported by a pivot between a braking position in which it is pressed against the outer peripheral surface of the flywheel and a release position in which it is separated from the outer peripheral surface, is urged toward this braking shoe. The present invention relates to an improvement of a braking system of a connected engine.

[0002]

2. Description of the Related Art Generally, an engine of a power lawnmower is provided with a braking device for promptly stopping the inertial rotation of a rotary system extending from a crankshaft to a cutting blade when the ignition circuit is deactivated. (See Japanese Utility Model Publication No. 1-23517).

[0003]

As disclosed in the above publication, in the conventional braking device of this type, the pivot of the brake shoe is arranged at a position radially outward from the outer peripheral surface of the flywheel. , When the operation wire for swinging the brake shoe in the releasing direction is arranged along the tangent line of the outer peripheral surface of the flywheel for space reasons, the pulling force of this operation wire is efficiently transmitted to the brake shoe. However, there is no choice but to adopt a complicated structure in which a cam mechanism is provided between the operation wire and the brake shoe, and the brake shoe is swung in the releasing direction by a cam that is rotated by pulling the wire.

The present invention has been made in view of such circumstances, and even if the operating wire arranged along the tangent line of the outer peripheral surface of the flywheel is directly connected to the brake shoe, the operating force of the operating wire is increased. It is an object of the present invention to provide a compact braking device having a simple structure, which can efficiently transmit a brake to a brake shoe.

[0005]

In order to achieve the above-mentioned object, the present invention provides the pivot of the brake shoe on the crankcase at a position closer to the inside of the outer peripheral surface of the flywheel, while the brake shoe has a flywheel. The first feature is that the operating arm is integrally formed so as to project outward from the outer peripheral surface of the device and to which the operating wire is connected.

In addition to the above features, the present invention has a second feature that the pressure contact portion of the brake shoe with respect to the outer peripheral surface of the flywheel is offset from the pivot in the rotational direction of the flywheel.

[0007]

According to the first aspect of the present invention, the pivot of the brake shoe is arranged inward of the outer peripheral surface of the flywheel, and the operating arm of the brake shoe is projected from the outer peripheral surface of the flywheel. , The effective length of the operation arm can be sufficiently secured, and therefore, the protrusion of the operation arm to the outer circumference of the flywheel is suppressed as much as possible, and the operation wire connected to this is arranged along the tangent line of the flywheel. Even then, it becomes possible to efficiently transmit the traction force to the brake shoes.

Further, according to the second aspect of the present invention, the brake shoe is of a leading type and can exert a large braking force by self-induction during braking.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, referring to FIG. 1, a walk-behind power lawn mower 1 includes a housing 4 supported by front wheels 2 and rear wheels 3.
Have. A vertical engine 5 having a crankshaft 6 arranged vertically is mounted on the upper surface of the housing 4.
The rotary cutting blade 7 attached to the lower end of the crankshaft 6 is arranged in the housing 4. A turf bag 9 is attached to the steering handle 8 fixed to the rear end of the housing 4, and the turf cut by the cutting blade 7 is stored therein.

2 to 4, a flywheel 10 is fixed to the upper end of a crankshaft 6 of an engine 5, and a large number of blades 11 constituting a cooling fan are integrally provided on the upper end surface of the crankshaft 6 so as to project. Further, a ring gear 12 with which a pinion of a starting motor (not shown) meshes is integrally formed on the outer periphery of the lower end portion.

The cylindrical outer peripheral surface 1 of the flywheel 10
A brake shoe 13 that cooperates with the shaft 0a is attached to a crankcase 14 that supports the crankshaft 6 via a pivot 15.

The pivot 15 is screwed to a boss 16 formed on the upper wall of the crankcase 14 at a position closer to the inner side than the outer peripheral surface 10a of the flywheel 10.

The brake shoe 13 is supported by the pivot 15 and extends between the crankcase 14 and the flywheel 10 and extends outwardly from the outer peripheral surface 10a of the flywheel 10. The arm 13a is bent from the tip of the arm 13a. The flywheel 10 has a pressure contact portion 13b facing the outer peripheral surface 10a, and a lining 17 is bonded to the pressure contact portion 13b.

As shown in FIG. 3, the brake shoe 13 has a braking position B where the lining 17 is pressed against the outer peripheral surface 10a of the flywheel 10 and a release position A where the lining 17 is separated from the outer peripheral surface 10a. And the brake shoe 13 is formed so that the press contact portion 13b is offset in the rotational direction R of the flywheel 10 from the pivot shaft 15 at least at the braking position B thereof. .

A connecting piece 18 is integrally formed at the front end of the pressure contact portion 13b of the brake shoe 13, and a brake spring 19 for urging the brake shoe 13 toward the braking position B is formed on the connecting piece 18.
Are connected.

Also, the arm portion 13a of the brake shoe 13
The operation arm 20 is formed integrally with the. The operating arm 20 is a flywheel 1 that crosses the center of the pivot 15.
The outer peripheral surface 10 of the flywheel 10 extending on the radius line of 0
a Window 2 that is opened in a partition wall 21 that is integrated with the crankcase 14 that projects outward and covers one side of the flywheel 10.
It is formed so as to penetrate 2. This operation arm 2
An operation wire 24 that is pulled by a brake release lever 23 (see FIG. 1) attached to the steering handle 8 is connected to the tip of 0. The operation wire 24 is arranged substantially along the tangent line of the outer peripheral surface of the flywheel 10,
Therefore, it is substantially perpendicular to the operation arm 20. Thus, when the operation wire 24 is pulled, the brake shoe 13 can be swung to the release position A via the operation arm 20.

An engine stop switch 25 for disabling an ignition circuit (not shown) is installed on the upper surface of the crankcase 14, and an operating lever 25a of this switch and the connecting piece 18 of the brake shoe 13 are linked by a coil spring. It is connected via 26. As a result, the engine stop switch 25 is linked to the braking position B and the releasing position A of the brake shoe 13 and is automatically switched between an operating state and a non-operating state.

Next, the operation of this embodiment will be described.

The brake release lever 23 is turned to the steering handle 8
If the operator grasps the operation wire 24 and pulls the operation wire 24, the brake shoe 13 is held at the release position A, and the engine stop switch 25 is in the inoperative state.
Can be started to perform lawn mowing work with the cutting blade 7.

Now, if the user releases the brake release lever 23 to stop the operation of the engine 5, the brake shoe 1
3 swings to the braking position B with the tension of the brake spring 19, and accordingly, the engine stop switch 25 operates to deactivate the ignition circuit, so that the brake shoe 13 gives friction to the outer peripheral surface 10a of the flywheel 10. The braking force can quickly stop the inertial rotation of the crankshaft 6 system.

In such a braking device, the pivot 15 of the brake shoe 13 has the outer peripheral surface 10 of the flywheel 10.
The effective length of the operation arm 20 can be ensured to be sufficiently large because the operation arm 20 is arranged inward of a and the operation arm 20 projects from the outer peripheral surface 10a of the flywheel 10. Therefore, even if the operating wire 24 is arranged along the tangent line of the outer peripheral surface of the flywheel 10 while suppressing the protrusion of the operating arm 20 to the outer periphery of the flywheel 10 as much as possible,
The traction force is efficiently transmitted to the brake shoes 13,
The release operation can be performed easily.

The pressure contact portion 13b of the brake shoe 13 is also provided.
Is offset from the pivot 15 in the rotational direction R of the flywheel 10, so that the brake shoe 13 is of the leading type, and a self-induction action occurs during braking. That is, the brake shoe 13 is encouraged to swing in the pressure contact direction with the flywheel 10 due to the frictional force with the flywheel 10, and can exert a large braking force.

In the above embodiment, various design changes can be made without departing from the gist of the present invention. For example, set the engine stop switch 25 to the brake release lever 2
It can be linked to 3.

[0025]

As described above, according to the first feature of the present invention, the pivot of the brake shoe is provided on the crankcase at a position closer to the inner side of the outer peripheral surface of the flywheel, while the brake shoe is attached to the flywheel. Since the operation arm that protrudes outward from the outer peripheral surface and is connected to the operation wire is integrally formed, the projection of the operation arm of the brake shoe to the outer circumference of the flywheel is suppressed as much as possible, and its effective length is secured sufficiently. Therefore, even if the operation wire arranged along the tangent line of the outer peripheral surface of the flywheel is directly connected to the operation arm, the brake shoe can be operated lightly, and the structure is simplified and downsized. be able to.

Further, according to the second aspect of the present invention, the pressure contact portion of the brake shoe with respect to the outer peripheral surface of the flywheel is offset from the pivot in the rotational direction of the flywheel, so that the brake shoe becomes a leading type and a great control. It can exert its power.

[Brief description of drawings]

FIG. 1 is a side view of a power lawnmower equipped with the device of the present invention.

FIG. 2 is a side view of an engine of the power lawnmower.

3 is a sectional view taken along line 3-3 of FIG.

4 is a sectional view taken along line 4-4 of FIG.

[Explanation of symbols]

5 ... Engine 6 ... Crankshaft 10 ... Flywheel 10a ... outer peripheral surface 13 ... Brake shoes 13a ... Arm part 13b ... Pressure contact part 14 ... Crankcase 15 ... Axis 19 ... Brake springs 20 ... Operation arm 24 ... Operating wire A: Release position B: Braking position

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Claims (2)

(57) [Claims] 1. A crankcase (14) for supporting a crankshaft (6) having a flywheel (10) fixed to one end thereof.
Brake shoes (13) and flywheel (10)
The brake shoe (13) is swingably supported by a pivot shaft (15) between a braking position (B) in pressure contact with the outer peripheral surface (10a) and a release position (A) separated from the outer peripheral surface (10a). ) Is connected to a brake spring (19) for urging the brake shoe toward the braking position (B). In a braking device for an engine, a brake shoe is provided at a position closer to the inner side of the outer peripheral surface (10a) of the flywheel (10). While the pivot (15) of (13) is provided on the crankcase (14), the brake shoe (1
The operation arm (2) is connected to the operation wire (24) projecting outward from the outer peripheral surface of the flywheel (10).
0) is integrally formed with an engine braking device. 2. The method according to claim 1, wherein the pressure contact portion (13b) of the brake shoe (13) with respect to the outer peripheral surface (10a) of the flywheel (10) is pivoted (1).
5) An engine braking device characterized by being offset in the rotational direction (R) of the flywheel (10) from 5).