JPH02112670A - Starter for small engine - Google Patents

Abstract

PURPOSE:To get rid of an excessive drop in rotation of an engine as well as to make it smoothly startable by installing a driving ratchet and a driven ratchet being engaged with a cam concentric with a reduction gear, in a pulley fixed to a crankshaft. CONSTITUTION:In a pulley 18 fixed to a crankshaft 16 of an engine, there are provided with paired centrifugal ratchets, namely, a driving ratchet 21a and a driven ratchet 21b energized inward by a return spring 20, and they are made so as to engaged with a cam 17 concentric with a reduction gear 7 both in the starting rotational direction and the reverse direction each. With this constitution, engagement between these paired driving and driven ratchets 21a, 21b and the cam 17 to rotation and drive at time of engine starting is kept up till the engine is ignited. Consequently, when engine speed gets lowering, rotation at the side of a motor 12 gives follow-up rotation at once so that there is no excessive drop in rotation of the engine, and since there is no impact, smooth starting takes place.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a starting device for an electric starter motor (starter motor) used as a starting device for a small engine.

(Prior Art) Recently, many agricultural tools and the like have started to use starter motors instead of recoil starters. However, agricultural equipment has a fixed usage period, and there is a problem that the battery dies after being left unused for a certain period of time, making it impossible to start in an emergency.The applicant first developed a ratchet-type starting device equipped with a recoil starter that can be started in an emergency. Special request 1976
It was proposed in No. 2-121758.

<Problem to be solved by the invention> However, in the conventional ratchet method of transmission,
When the engine speeds up temporarily in response to the rotation from the motor, the ratchet 31 and the cam 32 disengage as shown in FIG. collide and try to speed up the engine rotation. Therefore, the shock load caused by the collision puts strain on the transmission system, motor, and engine parts, causing failure of each part and causing the ratchet 3
Since the rotation of the engine rapidly decreases due to the delay in the engagement between the engine 1 and the cam 32, the magnetic ignition type has a problem in that the ignition performance deteriorates, resulting in poor starting.

Note that 34 indicates a return spring.

Therefore, the purpose of the present invention is to maintain the engagement between the ratchet and the cam until the engine ignites, thereby eliminating the extreme drop in engine rotation, and also to start a small engine that can be started smoothly without causing any collisions. The aim is to provide equipment.

(Means for Solving the Problems) In order to achieve the above object, the starting device of the present invention has a one-way clutch in a part of the starting motor and the speed reduction mechanism,
In a small engine starting device that transmits rotation using a centrifugal ratchet, a rotating body fixed to the engine crankshaft, such as a pulley, has a pair of centrifugal ratchets I, which are biased inwardly by a spring (return spring). That is, the driving ratchet and the driven ratchet are configured to engage with a cam provided coaxially with the reduction gear in the direction opposite to the starting rotation direction.

(Function) In the starter configured as described above, the engagement of the pair of driving ratchet, driven ratchet, and cam is maintained in response to the rotational drive at the time of engine startup until the engine ignites. When the engine speed starts to drop, the motor speed immediately catches up with the speed, so there is no drastic drop in engine speed, and no collisions occur, reducing the burden on each part and ensuring smooth operation without impact noise. A start-up takes place. After the engine starts, each ratchet is pushed outward against the return spring by centrifugal force.
The engagement with the cam is separated.

(Embodiment) Fig. 1 is a sectional view showing an embodiment of the starting device of the present invention, and Fig. 2 is a sectional view showing an embodiment of the starting device of the present invention.
The figure is a sectional view taken along the line AA in FIG. 1. In the figure, the case of a one-beam coil starter is attached to a crankcase 2, a support shaft 3 projects integrally from the inner center of the case 1, and a reel 4 is rotatably attached to the support shaft 3.

A lobe 5 is wound around the recess on the outer periphery of the reel 4, and after the rope 15 is pulled out between the reel 4 and the case 1, when the hand is released from the rope 15, the rope 5 is stored in the recess of the reel 4 again. A rewinding mainspring 6 is provided so as to do so.

Reference numeral 7 denotes a reduction gear, which is loosely inserted into and supported by a cylindrical shaft 8 screwed onto the support shaft 3. A first ratchet 9 provided on the side surface of the reduction gear 7 on the reel side is pivotally attached, and the inner part is rotated by a return spring 10. A cam portion 17 is provided on the opposite side, that is, on the crankshaft 16 side to be described later. On the other hand, reel 4
The ratchet 9 is attached to the concave portion of the inner periphery of the circular groove provided on the side surface of the ratchet 9.
It has a cam that is locked to the protrusion of the reel and rotates with the forward rotation of the reel 4, but idles when the reel 4 rotates in the opposite direction,
The opposing reduction gear 7 does not rotate, which is the same as in the prior art.

Next, a gear 14a for deceleration is fixed to the shaft 13 of the motor 12 attached to the motor fixing base 11, and a plurality of decelerating gears 14b to 14e are arranged between the motor fixing base 11 and the starter case 1. to drive the reduction gear 7. In addition,
A one-way clutch (roller clutch) 15 that transmits rotation only in one direction is fixed to the inner diameter portion of the gear 14e.

Note that the reduction gear 7 and the cam 17 may be integrated or separate, and any means for transmitting rotation is sufficient.

On the other hand, there is a rotating pulley on the engine crankshaft 16.
18 is fixed with screws or the like. This rotating body 18 is provided with a pin 19, as shown in FIG. It is inserted movably and is prevented from being removed by a retaining ring 22 or the like. Note that the pair of ratchets is a driving ratchet 21a and a driven ratchet 2, as in the embodiment shown in FIG.
1b may be positioned in the same direction and sandwich the protrusion of the cam 11. Further, as in the embodiment shown in FIGS. 4 and 5, the rotating body 18 is provided with a driving ratchet 21a and a driven ratchet 21b.
may be placed separately. In each embodiment, two pairs of driving and driven ratchets 21a and 21b are provided in order to eliminate couples during rotation transmission, but either one pair or multiple pairs may be used. Further, although the embodiment is configured so that a beam coil starter can be used in combination, the electric starter motor may be used alone. The operation will be explained below.

First, when the motor 12 starts, the reduction gears 14a to 1
4e, the reduction gear 7 rotates in the engine starting rotation direction. At this time, since the respective ratchets 21a and 21b attached to the rotary body 18 are engaged with the cam portion 17 of the reduction gear 7, rotation is transmitted to the engine. At this time, when the engine reaches the compression stroke, the load increases and the rotational speed slows down, and when the compression stroke is exceeded, the speed increases rapidly, and the engine rotation becomes faster than the rotation of the reduction gear 7, but the driven ratchet 21b is also engaged with the cam 17, so the reduction gear 7 rotates at the same speed as the engine.
The one-way clutch 15 fixed to the gear 14e idles and rotates faster than the rotation transmitted from the motor 12.

When the compression stroke starts again, the rotation of the engine slows down, and when the rotation by the motor 12 catches up, the one-way clutch 15
operates (engages) and speeds up the rotation of the engine. When the engine ignites, the rotating body 18 rapidly speeds up its rotation.
Each ratchet 21a.

The centrifugal force acting on 21b increases, and the return spring 2
When the motor 12 is pushed toward the outer periphery of the rotating body 18 against the urging force of The engine will be in normal operating condition.

When the engine is stopped, the rotation rapidly decreases and the centrifugal force acting on the ratchets 21a and 21b also weakens, so the return spring 20 tightens the ratchet 21a.

21b is pushed inward (toward the center) and engages with the cam 17, but since the one-way clutch 15 rotates in the slipping direction, only the reduction gear 7 and the gear 14e idle, and then the engine completely stops. It should be noted that even if the ratchets 21a, 21b and the cam 11 are engaged in the rotational direction of the engine as described above, there is no problem even if the engagement is temporarily maintained immediately after the idling engine is ignited.

Next, the operation of the recoil starter will be omitted since it is the same as the conventional one.

(Effects of the Invention) Since the present invention is configured as described above, the engagement between the ratchet and the cam is maintained until the engine ignites even when the engine starts up, so that the rotation of the engine is reduced. As soon as the engine speed starts to drop, the rotation on the motor side catches up and provides rotational force, eliminating the extreme drop in engine speed and ensuring good ignition.Also, since collisions do not occur, the load on various parts is reduced, and the impact is reduced. Great effects such as smooth start-up with no noise can be obtained.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the starting device of the present invention;
The figure is a sectional view taken along the line A-A in Figure 1, Figures 3 and 4 are front views showing examples of the engagement portion between the cam of the reduction gear and the ratchet that forms a pair of rotating bodies, and Figure 5 is The sectional view of FIG. 4 and FIG. 6 are front views showing the same conventional engaging portion. 1... Starter case, 2... Crank case, 3
...Spindle, 4...Reel, 5...Rope, 6...
・Spring, 7... Reduction gear, 11... Motor fixing base, 12... Motor, 13... Motor shaft, 14a~
14b... Reduction gear, 15... One-way clutch, 16... Crankshaft, 17... Cam, 18...
・Rotating body (pulley), 19... Pin, 20... Return spring, 21a... Drive ratchet, 21b.
... Driven ratchet, 22... Heavy wheel Figure 1

Claims (1)

[Claims] 1. In a small engine starting device that has a one-way clutch in the starting motor and part of the speed reduction mechanism and transmits rotation using a centrifugal ratchet, the engine crankshaft (16
) is fixed to a rotating body (18), and a spring (20) is attached inwardly.
A pair of centrifugal ratchets (21a, 21b
) is provided coaxially with the reduction gear (7) (cam (17))
A small engine starting device that is installed so that it engages in both the starting rotation direction and the opposite direction.