JPH0135142Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in the mounting structure of a blade holder in a lawn mower equipped with a crankshaft vertically mounted engine in which the crankshaft is vertically supported.

Conventionally, in the case of lawn mowers equipped with a vertically mounted crankshaft engine, in which the crankshaft is supported vertically, a blade holder is integrally attached to the lower end of the crankshaft by spline fitting, etc. A lawn mowing blade was bolted to the top. For example, if a protruding object such as a sprinkler hits the blade rotating at high speed, the impact will directly affect the crankshaft. Improvement of this is desired.

The present invention was developed in response to the above needs, and its purpose is to protect the crankshaft by having the blade holder absorb the impact that is applied to the rotating blade so that it does not directly impact the crankshaft. Furthermore, it is an object of the present invention to provide a blade holder mounting structure that improves the life and durability of a lawn mower.

In order to achieve such an objective, the present invention provides a lawn mower equipped with a vertically mounted crankshaft engine, in which a weak engagement part is provided on the upper surface of the blade holder to engage with an engagement part on the crankshaft side. The gist of the blade is that the rotational force of the crankshaft is transmitted to the blade holder through engagement, while the fragile engagement portion deforms in response to an impact applied to the blade, causing the impact to be absorbed by the blade holder. .

A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a side view of a lawn mower to which the present invention is applied, and FIG. 2 is a plan view thereof.

The front end of the frame 2 of the lawn mower 1 is provided with left and right front wheels 3, 3, and the rear end thereof is provided with rear wheels 4, 4 which form driving wheels, respectively, and a power unit 10 is mounted in the center of the frame 2. A downwardly opened housing 5, which serves as a cover for the lawn mowing blade, is vertically disposed at the bottom thereof. In the power unit 10, 11 is a fuel tank, 12 is a cooling intake port, and 13 is a muffler.Furthermore, a cut grass discharge duct 6 is provided on the rear of the housing 5, and a handle 9 is connected to the rear. A storage bag 7 for storing cut grass is provided between the connected left and right handle posts 8, 8.

Engine 2 forming the main part of power unit 10
0 is a crankshaft vertical engine (vertical engine) in which a crankshaft 40 is vertically supported as shown in FIG. A blade holder 70 is attached with the inventive attachment structure, and a lawn mowing blade 80 is attached via this blade holder 70.

First, the configuration of the engine 20 will be explained based on FIG. 3 showing a longitudinal side view thereof.

The engine 20 has a crank case 21, a cylinder block 27, and a cylinder head 28 that constitute a cylinder 26, which are integrally cast to form the case.The cylinder 26 is disposed so that its axis is horizontal, and A crankcase 21 is formed vertically so as to hang down from the base of the crankcase 26. At the top of the crankcase 21 is a cylinder 26.
An opening 22 is formed diagonally from the base of the holder, and this opening 22 is removably covered with a cover 31 made of a press-formed steel plate.

A piston 33 is slidably fitted into the cylinder 26, a spark plug 35 is installed diagonally from the front upper part of the cylinder head 28, and two left and right intake/exhaust valves 36, 36 ( In the illustration, one (1) is provided because it is a longitudinal side. valve 3
The valve stems 37 of 6 are attached to the respective rocker arms 3.
8, and the other end of each rocker arm 38 is engaged with the tip of a push rod 39, which is formed below the cylinder 26 and below the cylinder block 27 and the cylinder head 28. It is inserted into the pushrod passage 29, and a cover 32 made of a steel plate is attached to the front of the cylinder head 28.

On the other hand, a crankshaft 40 is vertically supported in the lower part of the crankcase 21 by upper and lower bearing parts 23 and 24 so as to be freely rotatable. It is configured with a cantilever type consisting of a pin 46.

Crank pin 4 of such a crankshaft 40
6 and the piston pin 34 of the piston 33 are connected by a connecting rod 51, and a stopper plate 47 is attached to the upper end surface of the crank pin 46 by a bolt 48 and a concave-convex engagement 49. The connecting rod 51 is prevented from coming off from the crank pin 46. Further, the stopper plate 47 is formed integrally with a holder plate 57 of a governor device 56 that controls the throttle of the carburetor, and this holder plate 57 extends sufficiently onto the axis of the crankshaft 40, and has a known governor on its upper surface. The device 56 is mounted coaxially with the crankshaft 40.

Furthermore, the upper and lower journals 42 of the shaft portion 41 of the crankshaft 40 are cantilevered at the lower part,
A gear 44 is formed on the shaft periphery between the upper and lower bearing parts 23 and 24 of the crankcase 21, and a recess 25 facing the gear 44 is horizontally formed on the cylinder 26 side between the upper and lower bearing parts 23 and 24 of the crankcase 21. camshaft 60
A gear 61 formed on the camshaft 60 is orthogonally meshed with the gear 44. Cams 62, 62 are formed on both sides of the gear 61 of the camshaft 60, and each cam 62 is connected to the base end of the push rod 39.
The base end of the lifter 63 inserted into the guide hole 29b formed in the base end wall 29a of the passage 29 abuts and engages.

Although not shown, an oil slinger is attached to one end of the camshaft 60, and as the oil slinger, which is integrated with the camshaft 60, rotates, it scrapes up the oil accumulated at the bottom of the crankcase 21 toward the crank web 45, and removes the oil from the engine. 20 is designed to be lubricated with a mist of oil.

Further, the gear 44 of the crankshaft 40 is horizontally disposed on substantially the same plane as the camshaft 60,
In addition, gears formed on an output shaft (not shown) disposed perpendicularly to the camshaft 60 are orthogonally meshed with each other, so that the driving force taken out directly from the crankshaft 40 to the output shaft is transmitted via the clutch mechanism. The output is output to the axle of the rear wheels 4, 4, and therefore the lawn mower 1
can run on its own.

Vertical engine 2 configured as described above
A lower end 41a of a shaft portion 41 of a crankshaft 40 projects and hangs below the crankcase 21 of No. 0, and a blade holder 70 is attached to the lower end 41a of the shaft.

The blade holder 70 is shown in FIG. 4, which is a bottom view, and FIG. 5, which is a developed longitudinal sectional view.
Pieces 72, 72 hang down from both long sides of a flat plate part 71 that is made of a press-formed SP steel plate and has a rectangular shape.
is formed, and a slightly tapered, substantially cylindrical cylinder 75 is provided in the center of the flat plate part 71, and
At the top of the cylinder 75, a mounting seat part 76 consisting of a substantially disk-shaped surface is formed integrally with the cylinder 75, and both short sides of the flat plate part 71 are slightly recessed downward. Recessed step portions 73, 73 are formed.

A mounting hole 77 for the crankshaft 40 is formed in the center of the mounting seat 76 of the blade holder 70, and is located on the center line between both long sides of the flat plate part 71, facing each other with the cylinder body 76 in between. Bolt insertion holes 74, 74 are bored in the portion.

Incidentally, bent pieces 72a, 72a bent outward are formed at the intermediate portions of the lower edges of both the hanging pieces 72, 72.

Further, in the present invention, an engagement protrusion 78 that stands upwardly and forms a weak engagement part at a portion facing the attachment hole 77 of the attachment seat 76 of the blade holder 70;
78 was formed.

That is, both the engaging protrusions 78 are attached to the flat mounting seat portion 7.
The base of the engagement protrusion 78 is continuous with the periphery of the mounting hole 77, and therefore after machining. A window portion 79 is formed radially outward of the engaging protrusion 78 . In the illustration, the engaging protrusions 78, 78 are arranged opposite to each other on the center line between both long sides, similarly to the bolt insertion holes 74, 74.

On the other hand, in the embodiment, as shown in FIG. 3, a male threaded portion 41b is provided at the lower end 41a of the shaft portion 41 of the crankshaft 40 that protrudes downward from the crankcase 21, and a male screw portion 41b is provided above the lower end 41a. A suction blade 16 for the removed grass is keyed 19, and engagement recesses 18, 18 are formed in the lower end surface of a mounting boss portion 17 of the suction blade 16 to face each other.

Note that in FIG. 3, the structure around the lower part of the shaft portion 41 of the crankshaft 40 that protrudes downward from the crankcase 21 is shown as an exploded longitudinal section in the same manner as in FIG. 5, so only one engagement recess 18 is shown. Not yet.

Therefore, the shaft portion 41 of the crankshaft 40
Loosely fit the blade holder 70 into the lower end 41a of the holder 70 with its mounting hole 77, and
Each engagement recess 1 has engagement protrusions 78 , 78 formed on the lower end surface of the mounting boss 17 of the suction vane 16 .
8 and 18, respectively, and then fasten a nut 87 to a male threaded portion 41b formed at the lower end 41a of the shaft, thereby attaching the blade holder 70 to the crankshaft 40.

Next, the lawn mowing blade 80 is applied to the flat plate part 71 of the blade holder 70 from below, and the bolts 88, 88 are inserted into the bolt insertion holes 74, 74 from above, respectively, and the nuts 89, 89 are tightened. The blade 80 is attached to the holder 70. Here, the blade 80 is made of a sufficiently long rectangular flat plate material, and the central part of both long sides is attached to the blade holder 70.
It is accommodated between both hanging pieces 72, 72 of.

A longitudinal section of the blade holder 70 and the blade 80 attached to the crankshaft 40 is shown in FIGS. 6 and 7.

When mowing the lawn, the blade holder 70 reliably transmits the rotation output from the crankshaft 40 by the engagement of the engagement protrusions 78 and the surface pressure due to the fastening force of the nut 87, and the blade 80 The desired rotation can be performed.

On the other hand, if a protruding object such as a sprinkler that protrudes from the lawn surface hits the rotating blade 80 during lawn mowing work, the engagement protrusion 78 which is a weak engagement part that stands up on the mounting seat 76 of the blade holder 70 ，
The blade holder 78 functions as a shear pin and deforms and shears, thereby resisting the fastening force of the nut 87 and causing the blade holder 70 to slip relative to the crankshaft 40. At the same time, blade holder 7
The vertical bending force acting on the mounting seat 76 acts on the windows 79 formed on the mounting seat 76, causing the mounting seat 76 to deform.

The above is shown in Figure 8.

Therefore, the impact applied to the blade 80 is caused by the deformation of the engagement protrusion 78 and the window 79 forming the fragile engagement part formed on the mounting seat 76 of the blade holder 70 and by the slip resisting the fastening force of the nut 87. 70, and a large impact does not directly act on the crankshaft 40.

After that, the lawn mower can be mowed again simply by replacing the blade holder 70.

In this embodiment, the engagement protrusion 78 formed on the upper surface of the blade holder 70 is engaged with the mounting boss 17 of the suction vane 16 attached to the shaft portion 41 of the crankshaft 40.
It may be directly engaged with. Also, a claw-shaped engagement protrusion 7
8 is cut and raised from the mounting seat 76 of the blade holder 70, and a window 79 is formed in the mounting seat 76. However, since the fragile portion can perform a shock absorbing action with just the engagement protrusion 78, the window 79 is A separate engagement protrusion may be fixed to the upper surface of the mounting seat portion 76 instead of forming a separate engagement protrusion.

As is clear from the above explanation, according to the present invention,
In a lawn mower equipped with a vertical engine, a weak engagement part is provided on the upper surface of the blade holder that engages with the engagement part on the crankshaft side and transmits the rotational force of the crankshaft to the blade holder. While ensuring the transmission of rotational force to the blade, the fragile engagement part deforms and disengages from the impact applied to the blade, causing the blade holder to slip and deform to absorb the impact. Therefore, it is possible to protect the crankshaft by preventing impact from directly acting on the crankshaft, and thus to improve the life and durability of the lawn mower.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a side view of the lawn mower, Fig. 2 is a plan view thereof, Fig. 3 is a vertical side view of the engine, and Fig. 4 is a bottom view of the blade holder. , FIG. 5 is a sectional view taken along the line 5-5 in FIG. 4, FIG. 6 is an explanatory longitudinal sectional view of the blade holder installed, FIG. It is a similar diagram showing the effect. In the drawing, 1 is a lawn mower, 20 is an engine, 40 is a crankshaft, 70 is a blade holder, and 78
79 is a window, and 80 is a blade.

Claims (1)

[Scope of utility model registration request] In a lawn mower equipped with a crankshaft vertically mounted engine in which the crankshaft is vertically supported, and a lawn mowing blade is attached to the lower end of the crankshaft via a blade holder, the blade holder has a cylindrical portion projecting upward. a fragile engagement portion that engages with the engagement portion on the crankshaft side and transmits the rotational force of the crankshaft to the blade holder, is integrally provided on the surface formed on the upper end side of the cylinder portion; A lawn mower blade holder mounting structure, characterized in that a window is formed on the surface.