JPH02124021A - Reaping blade driving mechanism of lawn mower of walking type - Google Patents

Abstract

PURPOSE:To prevent an engine from becoming an overloaded state by checking a sliding and contacting transmission state between a driving friction member and a trailing friction member by checking mechanism in application of sufficiently strong brake power by a brake member. CONSTITUTION:When a suspension state of reaping blade is operated to a driving state of reaping blade by rotary operation of a handling member 15, a gap between the handling member 15 and a brake member 16 is enlarged by a cam mechanism 25. Force of a spring 17 is larger than that of a spring 12, a driving friction member 13 receives downward pushing force but downward displacement is checked by checking mechanism A. The handling member 15 is released from a checked state by further rotating the handling member, the driving friction member 13 and a trailing friction material 11 become a sliding and contacting transmission state and brake power by a brake member 16 is dropped.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention has a cutting blade drive shaft that cantilevers downward inside the cutting blade housing, is rotatable integrally with the cutting blade drive shaft, and is mounted upwardly by a first spring. a driving friction member fitted externally so as to be able to slide freely in the axial direction in a state of force, and a driven friction member fixed to rotate integrally with the cutting blade and fitted externally to the cutting blade drive shaft for free rotation,
The blade is disposed so as to be able to slide into and away from the blade housing, and is biased downwardly through a second spring having a larger biasing force than the first spring on the lower surface side of the cutting blade housing, and slides into contact with the driven friction member to brake the cutting blade. The braking member and the driving member 19 are mounted integrally with the friction member so as to be vertically movable and freely rotatable, and between the braking member and the operating member that can be rotated around the rotation axis, the rotation of the operating member is provided. The present invention relates to a mowing blade drive structure for a walk-behind lawn mower, which is equipped with a cam mechanism that changes the distance between these two members in accordance with the operation to exhibit a mowing blade driving state and a mowing blade braking state.

[Background Art] The above-mentioned conventional cutting blade drive shaft is, for example, disclosed in 1788
It is disclosed in Publication No. 30.

That is, when the operating member is operated from the mower blade braking state by the braking member to set the mower blade driving state, the braking member remains in a state in which it is in sliding contact with the driven friction member,
The driving friction member is pushed down by the cam mechanism and is pressed into sliding contact with the driven friction member.

When the blade is further operated, the braking member moves upward due to the pressing reaction force of both friction members, the braking is released, and the mower blade is driven. This structure was designed to allow the cutting blade to be quickly braked when the power transmission is cut off from the cutting blade drive state.

However, in the switching operation of the operating member to the cutting blade driving side, there is a situation where the operating member comes into sliding contact with both the driven friction member and the braking member and the driving friction member and the driven friction member. I'm going to put it out.

At this time, if the above operation is performed quickly, no problem will occur, but if the above operation is performed slowly, for example, the drive shaft driven by the engine will receive braking force, which may cause engine trouble or cause the engine to stop. However, there was a risk that this would cause problems such as problems, and there was room for improvement.

The present invention aims to eliminate the above-mentioned disadvantages.

[Means to solve the problem]

A feature of the present invention is that, in the mowing blade drive structure of the walk-behind lawn mower having the above configuration, when the operating member is operated from the mowing blade stopped state to the mowing blade driving state on the lower side of the operating member.
A cam machine, which prevents the downward displacement of the driving friction member to a predetermined position during the run-up of the cam mechanism where the braking force between the braking member and the driven friction member decreases;
A check mechanism is provided to release the check state when the groove exceeds the predetermined position, and its functions and effects are as follows.

[For production]

That is, when the operating member is operated from the cutting blade braking stop state to the cutting blade driving state, the cam mechanism increases the distance between the operating member and the braking member, and the biasing force of the second spring is greater than that of the first spring. Therefore, the driving friction member receives a downward force, but since the downward displacement is checked by the restraining mechanism, the driving friction member and the driven friction member are restrained while a sufficiently strong braking force is applied by the braking member. There is no sliding transmission between the dynamic friction member and the dynamic friction member. When the operating member is further operated, the restraining state is released and the sliding transmission state is established, but at that time, the braking force is reduced.

〔Effect of the invention〕

Therefore, according to the present invention, even if the switching operation of the operating member is performed slowly, the transmission state is changed between the driving friction member and the driven friction member at the same time when a strong cutting blade braking force is applied by the braking member. This prevents the engine from becoming overloaded.

As a result, there is less risk of inconveniences such as engine trouble or engine stoppage occurring.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 7 shows a walk-behind lawn mower according to the present invention. This lawn mower has an engine (3) which has a vertically oriented output shaft (2) for driving the cutting blades on the top of the cutting blade housing (1) which also serves as a frame.
), and a cutting blade (4) which is driven and rotated around the axis of the output shaft (2) is installed inside the cutting blade housing (1).
), and a pair of left and right wheels (5) at the front and rear of the cutting blade housing (1), respectively.

(6) is provided. And at the rear, there is a control handle (
7) and a grass collection container (8).

Next, the drive mechanism of the cutting blade (4) will be explained.

As shown in FIG. 1, inside the cutting blade housing (1), a bearing (2) is fixedly supported by a bolt (9) at the lower end of the output shaft (2) extending downward in a cantilevered manner. A mower blade support member (11) as a driven friction member, which is connected with bolts to rotate the mower blade (4) integrally, is freely fitted on the output shaft (2) above the mower blade support member (11). The drive friction member (13) is externally fitted so that it can rotate integrally with the output shaft (2) by spline fitting and can freely slide in the axial direction while being biased upward by the first spring (12). be. Further, an operating member (15) is fitted around the boss portion of the drive friction member (13) via a bearing (14) so as to be rotatable and retractable around the output shaft, and a hollow drum-shaped member is provided on the upper part of the operating member (15). A braking member (16) is provided.

The braking member (16) has a plurality of second springs (17
), the second spring (17) is configured to be biased substantially uniformly downward over the entire outer circumference, and the biasing force of the second spring (17) is greater than the biasing force of the first spring (12). It is configured so that The upper end of each of the second springs (17) is supported by a fixed support plate (18) bolted to the lower surface of the engine (3) via a member (19).

Further, the upper surface of the cutting blade support member (11) is provided with a driven side friction part (20) having high wear resistance, and this driven side friction part (20) has a lower part of the driving friction member (13). Friction surface (
13a) and the outer peripheral lower end surface (16a) of the braking member (16)
The members (13) and (16) are configured to be able to slide into and away from each other as they move up and down.

As shown in FIG. 3, the operating member (15) has an insertion hole (21) for operating the output shaft (2), and the inner peripheral edge of the insertion hole (21) is provided with the bearing. (14)
Step engaging portion (15) for externally fitting and placing and fitting
a) is formed. In addition, an operating arm portion (15b) extends outward.
The brake member (16) projects outward through a long hole (22) formed in a part of the circumferential surface thereof. and,
Operation arm (15b) and! It is rotatably linked to a cutting blade clutch lever (23) provided on the handle (7) via a wire (24). This operating member (1
A cam @ mechanism (25) is provided between the brake member (16) and the brake member (16) to change the distance between the two parts H (15) and (16) in the vertical direction in accordance with the rotation operation. .

That is, three steel balls (26) are interposed between the two members (15) and (16), and both members (15) and
(16) has an engaging recess (27) into which the ball control (26) engages.
), (28>, and a recess (
28) is constructed with a cam groove whose engagement depth changes with rotation.

When the steel ball (26) is deeply inserted into the recess (28) and both members (15) and (16) are close to each other, the braking member (16) is pressed against the driven friction part (20). They slide into contact and are pressed by the large urging force of the second spring (17), braking the cutting blade (4) and stopping it, as well as turning the drive friction part.
13) is moved upward by the biasing force of the first spring (12),
The cutting blade support member (11) is separated from the cutting blade support member (11).

Furthermore, if the engagement of the steel ball (26) into the engagement recess, % (2!3) is shallow, and the distance between the two members (15) and (16) becomes large, the first spring (12) The biasing force of the second spring (1
Since the biasing force of drive friction member (13) is smaller than that of drive friction member (13),
) is pushed down and presses against the driven side friction part (20) of the cutting blade support member (11) to set the cutting blade in a driving state, and the reaction force causes the braking part 1 (16) to move upward. The braking state is released (see Fig. 1).

Then, when the mower blade is in the brake stop state, the operating member (1
5) when operating the cutting blade drive state, the braking member (
A check mechanism (8) is provided to check the contact between the drive friction member (13) and the cutting blade support member (11) only while a strong braking force is applied to the blade support member (16).

That is, three support pins (2) are attached to the fixed support plate (18).
At the same time, a substantially annular check plate (30) is bolted to the lower part of each support pin (29) along the lower surface side of the operating member (15), and this check plate 1 (30) Three cam grooves (31) as shown in FIG. 3 are formed at equal intervals in the circumferential direction on the upper surface side. On the other hand, three substantially hemispherical engaging protrusions (32) are protruded from the lower surface of the operating member (15) at positions corresponding to the cam grooves (31). The cutting blade (4) is moved by a strong braking force between the cutting blade braking position where the steel ball (26) in the cam mechanism (25) is deeply engaged in the engagement recess (28) and a predetermined position in the middle of riding on the cutting blade. While stopped, the engagement protrusion (32)
comes into contact with the upper surface of the check plate (30), and the operating member (15)
(See Figures 2 and 4).

When the steel ball (26) exceeds the predetermined position and rides on it, the engagement protrusion (32) engages in the engagement recess (28), and the biasing force of the second spring (17) causes the operation section to move! ;t (
15) is displaced downward, and the cutting blade is set to the driving state (see FIGS. 5 and 6).

With this configuration, when the cutting blade (4) is being braked with strong force, the power of the engine (3) is simultaneously applied to the cutting blade (4).
), and you can start mowing the lawn smoothly without the risk of engine trouble or engine stoppage.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the mowing blade drive structure of a walk-behind lawn mower according to the present invention, in which FIG. 1 is a vertical side view of the mower blade in the driven state, FIG. 2 is a vertical side view of the mower blade in the braked state, and FIG. 1 is an exploded perspective view of the main parts, FIGS. 4 to 6 are sectional views of the main parts showing the operating state, and FIG. 7 is an overall side view of the lawn mower.

Claims (1)

[Claims] Inside the cutting blade housing (1), the cutting blade drive shaft (2) extends downward in a cantilevered manner, and can rotate integrally with the cutting blade drive shaft (2), and slides in the axial direction while being biased upward by the first spring (12). A freely fitted driving friction member (13) and a cutting blade (4)
A driven friction member (11) is fixed to rotate integrally with the cutting blade drive shaft (2) and is freely fitted onto the cutting blade drive shaft (2) so as to be able to slide in and out of the blade housing (1). said first
a braking member (16) that is biased downward via a second spring (17) having a larger biasing force than the spring (12), and that slides in contact with the driven friction member (11) to brake the cutting blade (4); An operating member (15) is installed integrally with the driving friction member (13) so as to be vertically movable and freely rotatable, and is rotatably operable around the axis of rotation, and the braking member (16). Element(
15), these two members (15) and (1
A mowing blade drive structure for a walk-behind lawn mower, which is equipped with a cam mechanism (25) that changes the interval between the operating member (15) and exhibits a mowing blade driving state and a mowing blade braking state. ), when operating the operating member (15) from the cutting blade stopped state to the cutting blade driving state, the braking member (16)
In addition to checking the downward displacement of the driving friction member (13) to a predetermined position while the cam mechanism (25) is riding on the cam mechanism (25) where the braking force between the cam mechanism (25) and the driven friction member (11) decreases, the cam mechanism (25) ) A cutting blade drive structure for a walk-behind lawn mower, which is provided with a restraining mechanism (A) that releases the restraining state when the blade exceeds the predetermined position.