JPH065062B2 - Starter for small engine - Google Patents

Description

Detailed Description of the Invention

[Industrial applications]

The present invention relates to a starter for a small engine, and more particularly to a starter for a small engine using a starter motor.

[Prior art]

A small engine is used as a power source for a brush cutter, a power sprayer, and the like.This small engine requires external power at startup, so it has a recoil starter. It is necessary to rotate the crankshaft with the strength of the arm to overcome the compression process of the engine, which is one of the troublesome works for the elderly and women who have poor strength. In order to reduce the burden of such start-up work, a starter torque is provided with a starter motor by using a recoil starter,
There are those configured to start together with the starting torque of the starter motor, and those configured to start with the starting torque of the starter motor alone.

[Problems to be Solved by the Invention]

The starter using the starter motor as described above has a pinion attached to the output shaft of the starter motor that is constantly meshed with a ring gear provided on the crankshaft of the engine. A one-way clutch is provided between the crankshaft and the output shaft of the starter motor so that the starter motor will not be driven in reverse via the pinion with the output torque of. Since this one-way clutch has a function of transmitting the rotation torque, it is structurally complicated and requires considerable strength to transmit the rotation torque. This makes it unsuitable as a small engine mounted on a power atomizer. Therefore, in order to change the ring gear and the pinion from the constant mesh type to the constant mesh type only at the time of starting, the cell motor unit having the pinion is rocked with respect to the ring gear so that the pinion meshes with the ring gear. The applicant has previously proposed. However, since the starter motor is turned on and off, in other words, the pinion and the ring gear are meshed with each other, or the mesh is released, the meshing of the pinion is not released even though the engine is running. In some cases, the engine drives the starter motor in the reverse direction, causing the speed reduction mechanism to function as a speed-up mechanism, resulting in damage to the starter motor.

[Means for solving problems]

Therefore, the present invention is provided with a ring gear connected to a crankshaft, a cell motor unit having an output shaft having a pinion capable of meshing with the ring gear, and a position holding mechanism for holding the position of the cell motor unit. The unit is pivotally attached to the engine body and is swingable within a certain range in a plane orthogonal to the axis of the crankshaft.The position holding mechanism has an inflection point in the middle of the swing range of the starter motor unit. The pinion and the ring gear mesh with each other at one end beyond the bending point, and the meshing state is released at the other end beyond the inflection point of the pinion under the reaction force of the engine start. It is a feature.

【Example】

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the figure, reference numeral 10 indicates a casing forming an engine body, a part of the casing 10 is shown, and a crank shaft 11 which is an output shaft of the engine is supported by a bearing 12 in the casing 10. A cooling fan 13 is attached to the shaft end of the. The cooling fan 13 is provided with a clutch shoe mounting seat 14A that forms a centrifugal clutch. The clutch shoe 14 is mounted on this, and a clutch drum 15 is arranged along the outer periphery of its rotation region.
An output shaft 15A having a spline is formed in the center of the clutch and these are housed in a clutch housing 16. The cooling fan 13 has a blower blade 13A and a ring gear 17 on the outer circumference of the maximum diameter portion of the cooling fan 13. Then, in the casing 10 described above, the starter motor unit 20
Is pivotally attached to a lower portion of the clutch housing 16 by a pivot shaft 21 and is configured to swing in a plane orthogonal to the axis of the crankshaft 11. The lower portion of the clutch housing 16 has a swing range of the starter motor unit 20. An arc-shaped swing limiting frame 18 that limits the movement is formed. A stopper 22 protruding from the outer periphery of the holder of the starter motor unit 20 is fitted in the swing limit frame 18, and the swing limit frame 18
The starter motor unit 20 can be swung between the end portions 18A and 18B of 18. This cell motor unit 20 has a cylinder type holder 23, and a flange 24 is formed in the lower portion thereof, and the pivotal attachment 21 penetrates this flange 24, and the threaded portion 21A formed at the end thereof is attached to the housing 16. It is swingably supported by being screwed. Further, a spring hook 23A is provided on the outer peripheral portion of the holder 23 so as to project from the holder 23 and the clutch housing 16A.
The end portions 25A and 25B of the toggle spring 25 are hooked between the spring hook 16A and the spring hook 16A protruding from the outer circumference of the pivot shaft 21.
And an inflection point is formed on a line P-P connecting the center of the spring hook 16A with the spring hook 16A. The inflection point is a neutral point in the middle of switching the member between two postures, and the pinion of the starter motor unit 20 is engaged with the ring gear, or the inflexion point is exceeded and the engagement with the ring gear is released. It is used to maintain that alternative posture. Therefore,
A position holding mechanism is formed so that the cell motor unit 20 is rotated beyond the inflection point to be held at the positions of both ends of the swing region. On the outer periphery of the holder 23, a finger seat 26, which hangs a finger at the time of operation, is formed so as to bulge out, and by pushing the finger seat 26, the inflection point can be exceeded. This holder
A cell motor 27 is accommodated in 23, and is fixed to the holder 23 by a screw 27A, and a pinion 28 that can be meshed with the ring gear 17 is fixed to an output shaft 27B of the cell motor 27. The pinion 28 meshes with the ring gear 17 at one end of the swing region of the starter motor unit 20 and maintains the positional relationship in which the meshing is released at the other end. This starter motor 27 receives power from a portable battery (not shown) which is an external power source, has a pin jack 29 serving as a connection terminal with the power source, and has a switch 26A provided on the finger seat 26.
The power source of the starter motor 27 can be opened and closed by. The output shaft 15A protruding into the clutch housing 16 is spline-coupled with the transmission shaft of the brush cutter, though not shown. Next, the starting operation by the small engine starting device according to the present invention will be described. First, the starter motor unit 20
After inserting the pin plug extended from the external power source into the pin jack 29 of the above, and connecting it with the power source, push the finger seat 26 with your thumb etc. to move the starter motor unit 20 against the elasticity of the toggle spring 25 and center the pivot shaft 21. When it is rotated to the end of the swing control frame 18, the stopper 22 protruding from the holder 23 is moved over the inflection point.
The pinion 28 moves elastically from A and is stopped by hitting the end portion 18B. At this time, since the ring gear 17 is located at the end portion of the swing region of the pinion 28 included in the starter motor unit 20, the pinion 28 is When the switch 26A is turned on, the starter motor 27 is rotated to drive the ring gear 17 to start and rotate the crankshaft 11 (Fig. 4). When the engine starts, the ring gear 17 is the pinion
Since 28 is to be rotated, the cell motor unit 20 is swung by the drive reaction force against the elasticity of the toggle spring 25 beyond the inflection point, and the stopper 22 is attached to the end portion 18A of the swing limit frame 18. Return until restricted (Fig. 5). In other words, pinion
The meshing relationship between 28 and the ring gear 17 is released. In the process of releasing this meshing, the meshing between the ring gear 17 and the pinion 28 is continued until it crosses the inflection point. If the engagement between the two is released before the point of crossing the inflection point, the elasticity of the toggle spring 25 causes the pinion 28 to engage with the ring gear 17 again, which is inconvenient. Although the example in which the toggle spring is used as the position holding mechanism is shown, a simple tension spring may be used.

【The invention's effect】

As is apparent from the above description, in the small engine starting device of the present invention, the cell motor unit having the pinion capable of meshing with the ring gear provided on the crankshaft of the engine is swingably arranged. Since the pinion and the ring gear mesh with each other at one end of the swing region and the other end disengages, the swing position of the cell motor unit is held by a position holding mechanism such as a toggle spring. After pushing in once, the operator's hands can be released, and the one-way clutch is unnecessary because the pinion and ring gear mesh only during startup work.After the engine is started, the pinion of the cell motor unit is driven by the ring gear drive reaction force. In response to this, the meshing is automatically released, and the starter motor is not driven by the engine after startup. Of the rotor damage or of, of the pinion damage and the like can be prevented.

[Brief description of drawings]

The accompanying drawings show an embodiment of the present invention. Fig. 1 is a vertical sectional view of a starter for a small engine, Fig. 2 is a sectional view taken along line II-II in Fig. 1, and Fig. 3 is Fig. 1 III. Fig. 4 is a sectional view taken along line -III, Fig. 4 is an explanatory view of a state where the ring gear and the pinion are meshed, and Fig. 5 is an explanatory diagram of a state where the ring gear and the pinion are disengaged. 10 ... Casing 11 ... Crankshaft, 12 ... Bearing, 13 ... Cooling fan, 14 ... Clutch shoe, 14A ... Mounting seat, 15 ... Clutch drum, 15A ... Output shaft, 16 ... Clutch housing, 16A ...
Spring hook, 17 ... Ring gear, 18 ... Rocking limit frame, 18A, 18B
... End 20 ... Cell motor unit 21 ... Pivot shaft, 21A ... Screw part, 22 ... Stopper, 23 ... Holder, 23A ... Spring hook, 24 ... Flange, 25 ... Toggle spring, 2
5A, 25B ... end, 26 ... finger rest, 27 ... cell motor, 27B ... output shaft, 28 ... pinion, 29 ... pin jack

Claims (1)

[Claims] 1. A starter for a small engine, which starts by transmitting a rotational torque from the outside to a crankshaft, having a ring gear connected to the crankshaft and a cell motor unit having an output shaft having a pinion that can mesh with the ring gear. And a position holding mechanism for holding the position of the starter motor unit, wherein the starter motor unit is pivotally attached to the engine body and is swingable within a certain range in a plane orthogonal to the axis of the crankshaft. The holding mechanism has an inflection point in the middle of the swing range of the starter motor unit, the pinion and ring gear mesh at one end beyond the inflection point, and the pinion exceeds the inflection point due to the engine reaction force. A starting device for a small engine, characterized in that the engagement state is released at the other end.