JPH0149443B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power lawn mower equipped with a vertical engine having a vertical crankshaft.

A lawnmower is put into practical use that runs on power and mowing the lawn while moving by rotating a cutter blade.

In such lawn mowers, a vertical engine with a vertically disposed crankshaft is used to rotate the cutter blade in a horizontal plane close to the ground, and the cutter blade is attached to the lower end of the vertically disposed crankshaft. It will be done.

FIG. 9 is a plan view of such a lawn mower, schematically showing the engine in transparent view.The lawn mower 50 has wheels 52 disposed at the four corners of a body 51, an engine 53 mounted on the body 51, and A cutter blade 54 is attached to the lower end of the vertically arranged crankshaft, and the periphery and lower surface of the blade 54 are covered with a housing 55. A handle 56 extends obliquely upward at the rear of the machine body 51, and a cut grass discharge part 57 is provided on one side of the upper surface of the housing 55, and one end of this is fixed to one side of the handle 56. It is connected to the base end of the storage bag 58.

In the above, the cylinder portion 53 of the engine 53
1 is desirably the same as the longitudinal axis of the body 51. This is because the rotation of the crank web due to the rotation of the crankshaft causes wobbling around the crankshaft shaft, and the primary inertial force caused by the rotation of the crankshaft causes vibrations in the Y direction in the longitudinal direction of the aircraft as shown in Figure 9. Vibration in the X direction in the left and right direction occurs. Such vibrations are transmitted to the handle 56 through the body of the machine, and to the operator's sense, vibrations in the left and right directions are not so noticeable, but vibrations in the front and rear directions are easily felt. Therefore, the engine 53
The crank balance is set so that the primary inertia force is large in the horizontal direction and small in the longitudinal direction.

In the above, the grass discharge part 57 is provided on the side of the engine.
is provided, the cylinder part 531 of the engine
It is necessary to incline its axis in the opposite direction as N ₁ in consideration of the turf introduction part in the housing 55, etc. If such an arrangement is adopted, the direction of the primary inertial force of the engine will be Y in Fig. 9. ₁ , _X1 direction,
The vibration component of the handle 56 in the longitudinal direction becomes large, and it is difficult to suppress or eliminate the vibration in the longitudinal direction by conventional crank balance adjustment.

The present invention has been made in view of the above.

The object of the present invention is to provide a lawn mower equipped with a vertical engine with a vertically disposed crankshaft, when the engine is disposed such that its cylinder axis is inclined with respect to the longitudinal axis of the machine body. To provide a lawn mower that is easy to operate by reducing and eliminating vibration components in the longitudinal direction of a handle due to primary inertial force as much as possible.

In order to achieve the above-mentioned object, the gist of the present invention is to make the crankshaft's crank web oddly shaped so that one side of the crankshaft is shortened from the other side from the axis, thereby making the crankshaft asymmetrical.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a plan view schematically showing an engine of a lawn mower, FIG. 2 is a side view of the same, FIG. 3 is a vertical side view of the engine, and FIG. 4 is a front view of a crank web.

The lawn mower 1 includes wheels 3 at the four corners of the machine body 2, a handle 4 extending rearward and upward from the rear of the machine body 2, and a planar circular housing 5 provided between the wheels 3 at the four corners of the machine body 2. 5 is opened downward, and a cutter blade 6 is housed therein. A power unit 7 is mounted on the housing 5, and a grass discharge part 8 is placed on one side of the housing 5 so as to face rearward. It is provided. A grass storage bag 9 is disposed on this side of the handle 4, and the bag 9 has its base end connected to the rear end of the discharge section 8, and its tip end latched to the side of the front end of the handle 4. .

In the above, the engine 10, which constitutes the main part of the power unit 7, is arranged such that the axis N of the cylinder part 103 is inclined in the opposite direction to the exhaust part 8 with respect to the longitudinal axis _N1 of the body 2. The details of the engine 10 are as shown in FIG. 3, and the embodiment shows a vertical engine in which the crankshaft of a cantilever type crankshaft without a crank pin part and the other web is vertical.

Reference numeral 101 denotes a vertically disposed crankcase, and a cylinder section 103 consisting of a cylinder block section 104 and a cylinder head section 105 extends horizontally from the top of the crankcase 101 to the side, and a bearing provided in the middle section of the crankcase 101. The web 202 of the crankshaft 20 is supported in the radial direction by supporting the upper and lower parts of the shaft part 201 in the axial direction by the upper and lower bearing parts 102a and 102b. The lower surface shoulder portion 203 and the top portion 102c of the bearing portion 102 support the thrust direction. horizontal cylinder part 1
A cylinder sleeve 106 is fitted inside 03,
A piston 107 is slidably fitted therein, and a small end 111 of a horizontally disposed connecting rod 110 is fitted and connected via a piston pin 109 that fits into a pin hole 108 provided in the piston 107. The big end 112 of the crank web 202
The large end portion 112 is fitted and connected to a pin portion 204 provided eccentrically with respect to the shaft portion 201 on the upper surface.
A plate 113 fixed to the end face of the governor 114 prevents it from coming off in the axial direction, and the plate 113 also serves as a base member of the governor 114. A gear part 205 is provided at the intermediate part of the shaft part 201 of the crankshaft 20, and this gear part 205 is orthogonally meshed with a gear part 207 of a camshaft 206 disposed perpendicularly to the shaft part 201.
The push rod 208 is engaged with the lifter 209 of the
engages one end with the rocker arm 210 to open and close the intake/exhaust valve 211. The lower end of the shaft of the crankshaft 20 extends below the bottom of the crankcase 101, and the cutter blade 6 is connected thereto via a holder 601.

An opening 11 is formed between the upper part of the crank case 101 and the upper base end of the cylinder block 104.
5, the opening 115 is formed obliquely with the upper base end side of the cylinder block part 104 being higher and the crankcase 101 part being lower, and the opening 115 is covered with a cover 116 made of a steel plate press molding name, etc.
The cover 116 is removable. An upward semicircular notch 117 is provided at the upper base end of the cylinder block portion 104 including the cylinder sleeve 106, and the notch 117 is set larger than the diameter of the pin 109.

Fig. 2 shows the side view of the power unit 7 on the fuselage, and Fig. 1 schematically shows the engine, but Fig. 2 shows the external appearance. In the figure, 11 is a cover that covers the outside, and 12 is a fuel tank , 13 is a cooling air intake section.

As described above, the axis N of the cylinder portion 103 of the engine 10 is inclined by θ° in the direction opposite to the exhaust portion ₈ with respect to the longitudinal axis (center line) N 1 of the body 2 . Therefore, the direction of the primary inertial force (vibration) caused by the rotation of the crankshaft 20 of the engine 10 is crank-balanced so that the direction perpendicular to the axis of the temporary cylinder portion 103 (left-right direction) is larger than the front-rear direction. The axis line N is also the axis line
Since it is tilted at θ° with respect to N ₁ , it becomes larger in the diagonal direction of X ₁ in Figure 1, and the vibration component in the front and rear direction to the handle 4 is caused by being swung diagonally. Become.

Therefore, in the present invention, the crankshaft is configured as follows.

That is, as shown in FIG. 4, the web 202 of the crankshaft 20 has a base portion 202a that is approximately the same width as the pin portion hanging from the axial base portion of the pin portion 204.
and a right half weight portion 202b that is curved and bulged outward as shown on the right side of the figure.Generally, the left side has a symmetrical shape with the right side, but the present invention
02c, the left end edge 202d of the base 202a is significantly extended toward the tip compared to the right half 202b, and extends outward from near the tip in a direction perpendicular to the end edge 202d, forming an arcuate outer edge of the web 202. 202e, the left and right sides of the web 202 are asymmetrical with respect to the base 202a, and there is a cutout 2 on one side (the left side in the figure).
02f is formed, and the weight balance of the web 202 becomes asymmetric between the left and right sides, and one side becomes heavier. In the above, the connecting rod 110, the piston 107, and the piston pin 109 are schematically shown with imaginary lines, but the rotational direction of the crankshaft 20 is indicated by arrow A, and the front of the web 202 in the rotational direction is the cutout 202f.

As described above, as the crankshaft 20 rotates, the web 202 also swings around the pin portion 204, but the front web half 202c in the rotation direction is light and the rear web half 202b is heavy. The centrifugal force of the rear half body is larger than that of the front half body in the direction of rotation of the web 202, and acts to offset vibrations in the front and rear parts during rotation.
By setting the angle θ, the size of the cutout 202f, and the weight imbalance between the left and right halves, the primary inertial force in the _X1 direction described above is converted to the X direction in Figure ₁ , which is perpendicular to the aircraft axis N1. This means that the longitudinal vibration of the aircraft body can be reduced and suppressed as much as possible compared to the horizontal vibration.

Note that one half 202c of the crank web 202
By forming the asymmetric cutout 202f on the side as described above, the cover 116 of the engine 10 is removed in advance, and the arcuate edge 202e of the web 202 that rotates the crankshaft 20 is removed as shown in FIGS. 5 and 6. Skirt portion 107a of piston 107
It faces the bottom dead center so as to face the lower end 107b. In this state, the axial end surface of the piston pin 109 faces the notch 117 provided at the lower end of the cylinder portion 103 in the axial direction, and in this state, the piston pin 109 is pulled out in the direction of the notch 117. As a result, the piston 107 is connected to the small end 1 of the connecting rod 110.
11, and then remove the connecting rod large end 112 from the pin portion 204 of the crankshaft 20.

As a result, the crankshaft 20, piston 1
07 becomes free, rotate the crankshaft 20 from the above state to a crank angle of 90°,
The previously described notch 202f of the web 202 is attached to the piston 1.
Place it so that it faces the 07 side. This missing part 202
A space in which the piston 107 is housed is formed between f and the cylinder part 103, and the piston 107 is pulled down to face between the notch part 202f and the lower end of the cylinder part 103, and the cover 116 is removed in the direction of the open part 115. Then, pull out the piston 107. This allows the piston to be removed without disassembling the engine, allowing maintenance such as piston ring replacement to be performed. This is the seventh
It is shown in Fig. 8.

The above is possible only in an embodiment in which the crankcase is configured with a cantilevered crankshaft as described above and the crank web according to the present invention is used.

Although the embodiment has shown an example of a cantilevered crankshaft, the present invention can also be applied to a double-sided crankshaft.

As is clear from the above, according to the present invention, a vertical engine with a vertical crankshaft is mounted,
In a lawn mower in which the cylinder part of the engine is inclined with respect to the longitudinal axis of the machine due to the layout of the lawn discharge part, etc., the cylinder part axis is arranged so as to be inclined by making the crank web asymmetrical. However, the direction of the primary inertia force can be directed perpendicular to the longitudinal axis of the aircraft.
The vibration component in the longitudinal direction can be minimized and suppressed, and the cylinder axis is tilted to mainly vibrate in the lateral direction, which is equivalent to or less than the type in which the cylinder axis is oriented in the longitudinal direction. Vibration can be suppressed, which is preferable for lawn mower operation.

Furthermore, since a notch is provided on one side of the crank web to accommodate the lower part of the piston, the piston can be removed from the engine without disassembling the engine, making it easier to disassemble, assemble, and maintain the piston, piston pin, piston ring, and connecting rod. Improve your sexuality.

[Brief explanation of drawings]

Fig. 1 is a plan view of the lawnmower and schematically shows the engine, Fig. 2 is a side view of the same, Fig. 3 is a vertical sectional view of the engine, Fig. 4 is a front view of the crank web,
Fig. 5 is a front view of the piston removed, Fig. 6 is a longitudinal sectional side view of the same, Fig. 7 is a front view of the piston removed, Fig. 8 is a longitudinal sectional side view of the same, and Fig. 9 illustrates the technical proposition of the present invention. This is a diagram similar to FIG. 1 for explanation. In addition, 1 in the drawing is a lawn mower, 10 is an engine, and 103
is the cylinder part, 20 is the crankshaft, 202
202f is a crank web, and 202f is a missing part.

Claims (1)

[Claims] 1. In a power lawn mower equipped with a vertical engine in which the crankshaft is vertical and the cylinder part is arranged horizontally, the axis of the cylinder part of the engine is on one side with respect to the longitudinal axis of the machine body. In addition to tilting the crankshaft, a crank web is attached to the crankshaft.
A lawn mower characterized in that the clamp web is shaped asymmetrically by providing a notch on one side of the crank web in which the lower part of the piston can be accommodated.