Engine starter

Details Engine starter Engine starter

1989-11-10

1992-11-03

Braun, Leslie A.

Machine element or mechanism

Engine starters

74 7C, 1231791, 12317925, 192 42, 200 6185, F02N 1502, F02N 1700, F16D 1304, H01H 906

Patent

active

051598450

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to an engine starter using a motor for starting a small-sized engine adopted for a portable working machine such as a brush cutter.


BACKGROUND ART

FIG. 4 shows a conventional starter which uses a motor for starting an engine. In the figure, a crankshaft 1 is provided with a fixed driven gear 3. The driven gear 3 is covered with a gear case 7 fixed to a crank case 5. A starter motor 9 is fitted to the gear case 7. The starter motor 9 has a rotary shaft 11 whose periphery is threaded to provide a screw portion 13 on which a drive gear 15 is movably fitted. The drive gear 15 removably engages with the driven gear 3.
When the starter motor 9 is actuated, the drive gear 15 tries to be stationary due to its inertia so that the drive gear 15 rotates relative to the rotary shaft 11. As a result, the drive gear 15 axially moves due to the screw portion 13 and engages with the driven gear 3 to rotate the crankshaft 1 to start the engine.
After the engine is started, a circumferential speed of the driven gear 3 exceeds that of the rotary shaft 11 so that the drive gear 15 rotates reversely relative to the rotary shaft 11. As a result, the drive gear 15 separates from the driven gear 3 and returns to its original position due to the screw portion 13.
According to this conventional arrangement, the mechanism for axially moving the drive gear 15 is complicated, and the gears may be injured due to shocks caused by the moving drive gear 15. Further, the driven gear 3 of large inertia fixed to the crankshaft 1 shall always be rotated together with the engine so that the crankshaft and bearings shall have sufficient strength. In addition, the rotary shaft of the starter motor and the gears tend to be injured because the driven gear 3 of large inertia is suddenly rotated by the engagement with the drive gear 15.


DISCLOSURE OF INVENTION

According to the present invention, a driven gear is journaled to a engine crankshaft through a nonreturn clutch. The driven gear is covered by a gear case which is fixed to a crankcase. A starter motor is fitted to the gear case, and a rotary shaft of the starter motor is fixedly connected with a drive gear which is always engaging with the driven gear. When started, a rotational speed of the driven gear, etc., increases gradually as a rotational speed of the starter motor increases, so that no shock may be applied to the gears and bearings which, therefore, do not wear easily. When the rotational speed of the crankshaft exceeds that of the driven gear, the crankshaft rotates in a opposite direction relative to a rotational direction of the driven gear so that the nonreturn clutch is released. By stopping the starter motor after the actuation of the engine, the driven gear stops while the crankshaft is rotating, so that the driven gear of large inertia never rotates at high speed.


BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing a brush cutter according to the present invention;
FIG. 2 is a sectional side view showing a first embodiment of the present invention;
FIG. 3 is a sectional front view showing essential part;
FIG. 4 is a sectional side view showing a prior art example;
FIG. 5 is a sectional side view showing an engine provided with a recoil starter according to another embodiment of the present invention;
FIG. 6 is a perspective view showing a brush cutter provided with a battery disposed on a shoulder band;
FIG. 7 is a sectional plan view showing the battery;
FIG. 8 is a perspective view showing a brush cutter provided with a battery position adjustably disposed on a connection pipe;
FIG. 9 is a sectional front view showing the battery;
FIG. 10 is a sectional side view showing a battery portion fitted to a connection pipe with a plurality of fixtures;
FIGS. 11 to 14 are front views showing the fixtures, respectively;
FIGS. 15 and 16 are a side view and a sectional side view, respectively, showing a switching device;
FIG. 17 is a sectional front view showing essential part of the switching device;
FIG. 18 is a

REFERENCES:
patent: 2865358 (1958-12-01), Musgrave
patent: 2939448 (1960-06-01), Hansen
patent: 3696593 (1972-10-01), Thorud et al.
patent: 4135068 (1979-01-01), Burns
patent: 4727828 (1988-03-01), Ueno et al.
patent: 4771148 (1988-09-01), Bersonnet
patent: 4821691 (1989-04-01), Ueno et al.
patent: 4887476 (1989-12-01), Yokoyama

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