JP2505893Y2 - Small general-purpose engine starter structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a starter structure of a small-sized general-purpose engine mainly used for a brush cutter or the like.

(Prior Art) In recent years, this type of engine is equipped with a starter motor in order to facilitate a starting operation.
As a general example of an engine equipped with a starter motor, there is a pinion gear projection type in which a pinion gear projects at the time of starting by the starter motor and meshes with a starting ring gear, and the rotation of the starter motor is transmitted from the ring gear to the crankshaft.

In such a type in which the pinion gear protrudes only at the time of starting, the strength of the rotating shaft of the starter motor supporting the pinion gear is required due to the impact of the pinion gear. Therefore, the rotating shaft diameter and the starter motor itself are required. Must be increased.

On the other hand, as a starter structure capable of achieving downsizing, for example, as shown in FIG. 2, a type in which the pinion gear 20 of the starter motor 7 is constantly meshed with the ring gear 18 has been developed. However, since the ratchet wheel 17 having the ring gear 18 is rotatably supported by the clutch wheel 8 on the crankshaft 5 side via the bearing 30, the following occurs.

In the self-driving state after the engine is started, the crankshaft 5 and the clutch wheel 8 are rotating, while the ratchet wheel 17 is stopped.
In 30, the inner race is rotating and the outer race is stopped. That is, the inner race and the outer race of the bearing 30 are constantly rotating relative to each other during engine operation, so that the bearing 30 is quickly worn and damaged, and its life is shortened. Moreover, when a resistance force is generated in the bearing 30 due to the damage of the bearing 30, a ratchet wheel 17 is accompanied, and the phenomenon is transmitted to the rotating shaft 21 of the starter motor 7, the starter motor 7 is rotated, and the output of the engine is increased. Cause a decrease in. In addition, the life of the starter motor 7 is shortened.

 As a precedent, there is the actual exploitation sho 63-79471.

(Object of the Invention) The object of the present invention is to make the starter structure compact, to improve the life of the bearing supporting the ratchet wheel, and to prevent the engine output from decreasing due to it.

(Technical Means for Achieving the Purpose) In order to achieve the above-mentioned object, the present invention is configured such that a starting ring gear 18 formed on a ratchet wheel 17 is constantly meshed with a pinion gear 20 of a starter motor 7 to form a crankshaft 5. The boss portion 8a of the clutch wheel 8 is taper-fitted and fixed to the tip portion, and the ratchet mechanism for transmitting the rotation of the starter motor 7 is interposed between the ratchet wheel 17 and the clutch wheel 8 only from the ratchet wheel side to the clutch wheel side. In a starter structure for a small general-purpose engine, a boss portion which is formed at an end portion of a crankcase 1 in the crankshaft direction and has a crankshaft supporting inner peripheral surface and an outer peripheral splint portion coaxial with the crankshaft, and a boss portion of the boss portion. The cylindrical portion 2a that is fitted and fixed to the brazing portion and surrounds the outer periphery of the crankshaft end portion with the same axis as the crankshaft core The body includes a starter case 2 and a case lid 3 fixed to the starter case 2. The tip of the rotary shaft 21 of the pinion gear 20 is supported by the case lid 3, and the boss 17a of the ratchet wheel 17 is provided. Is rotatably supported by the tubular portion 2a of the starter case 2 via a bearing 25.

(Operation) When the engine is started, the ratchet wheel is rotated by the rotation of the starter motor via the pinion gear and the starting ring gear, and power is transmitted from the clutch wheel to the crankshaft via the ratchet mechanism to rotate the crankshaft.

After the engine is started, the ratchet mechanism is disengaged due to, for example, inertial force generated by rotation of the clutch wheel, and the ratchet wheel and starter motor are stopped.

In the engine operating state, the ratchet wheel is supported by the starter case via bearings,
Moreover, since the ratchet wheel and the starter case are both stationary, the bearing itself is maintained stationary.

(Embodiment) FIG. 1 is a vertical sectional view of a starter portion of a small-sized general-purpose engine to which the present invention is applied. In FIG. 1, the crankshaft 5 is supported at the crankshaft direction end of the crankcase 1. The starter case 2 is fixed to the outer circumference of the portion to be fitted with an anchor, and a starter motor (electric motor) 7 is fixed to the starter case 2 and a case lid 3 is covered. The rotary shaft 21 of the starter motor 7 extends into the starter case 2 and the pinion gear 20 is fixed.

The crankshaft 5 also extends into the starter case 2, and the boss portion of the clutch wheel 8 is provided at the tip of the crankshaft.
8a is fitted with a taper and is fixed by a bolt 9.
A centrifugal clutch shoe 12 is supported on an axial end surface of the clutch wheel 8 via a return spring 13 by bolts 10 and the like so as to be able to expand. A clutch drum 11 is arranged on the radially outer side of the clutch shoe 12, and the clutch is connected by expanding the clutch shoe 12 radially outward by a centrifugal force.

Ratchet pawl is provided on the outer peripheral side of the clutch wheel 8.
A ratchet pawl 15 is rotatably supported by a bolt 14, and the ratchet pawl 15 is urged radially outward by a spring or the like (not shown).

The ratchet wheel 17 is arranged on the outer side in the radial direction of the boss portion 8a of the clutch wheel 8. The ratchet wheel 17 has ratchet teeth 16 that engage with the ratchet pawl 15 and a starting end formed on the outer peripheral end surface. Ring gear 18,
The crankshaft 3 and a boss portion 17a coaxial with the crankshaft 3 are integrally provided.

In the starter case 2, a tubular portion 2a is integrally formed with the clutch wheel boss portion 8a at the same axial center as the clutch wheel boss portion 8a and at intervals in the radial direction. The ratchet wheel is provided on the outer peripheral surface of the tubular portion 2a. A boss 17a of 17 is rotatably supported via a plain bearing 25. Ratchet teeth
As described above, the ratchet pawl 15 is engaged with the 16 so that the rotation of the starter motor 7 is transmitted only from the ratchet wheel 17 side to the clutch wheel 8 side, and when the engine is operating, the ratchet is generated by the inertia force generated by the rotation of the clutch wheel 8. The pawl 15 is adapted to move away from the ratchet tooth 16.

The ring gear 18 is constantly meshed with the pinion gear 20 of the starter motor 7, and the rotary shaft 21 of the starter motor 7 is also engaged.
The tip end of is supported by the case lid 3.

The operation will be briefly described. When the starter motor 7 is operated to rotate the rotary shaft 21, the ring gear 18 is rotated by the pinion gear, and the ratchet teeth 16 of the ratchet wheel 17 are rotated.
Power is transmitted to the clutch wheel 8 via the ratchet pawl 15 and the crankshaft 5 rotates.

While the engine is running after starting, the ratchet pawl 15 does not engage with the ratchet teeth 16 and rides over it to rotate.
Power is not transmitted from the clutch wheel 8 to the ratchet wheel 17. Moreover, since the starter case 2 and the ratchet wheel 17 are stationary during engine operation, friction (rotation) does not occur in the bearing 25 between them. Therefore, the bearing 25 is less damaged and has a longer life.

(Other Embodiments) As a bearing arranged between the ratchet wheel and the starter case cylinder, a needle bearing or a ball bearing may be arranged.

(Effects of the Invention) According to the present invention as described above: (1) Since the ring gear and the pinion gear are constantly meshed with each other, the strength of the rotating shaft of the starter motor may be smaller than that of the pinion gear protruding type. It is possible to easily and inexpensively equip an engine with a small displacement with a starter motor using a small motor.

(2) Since the ring gear and the pinion gear are constantly meshed with each other, the outer diameter of the starter motor can be made compact compared to the pinion gear protruding type.

(3) Since the ratchet wheel is rotatably supported by the starter case via bearings, both the inner and outer sides of the bearing are in contact with both the starter case cylinder and the ratchet wheel while the engine is running. By doing so, the bearing is less damaged or worn, and the life of the bearing is extended.

Further, this prevents the ratchet wheel from rotating along with the bearing during engine operation, thereby preventing transmission of power from the crankshaft side to the starter motor.
That is, during engine operation, the rotation of the crankshaft is not transmitted to the starter motor to rotate the starter motor, and it is possible to prevent the engine output from decreasing.

(4) Since the ratchet wheel 17 and the starter motor 7 having the pinion gear 20 meshing with the ratchet wheel 17 are attached to one fixed member called the starter case 2, the accuracy of the shaft between the ratchet wheel 17 and the pinion gear 20 is improved.

(5) The starter case 2 is fixed to the outer circumference of the crankshaft supporting portion of the crankcase 1 by the brazing fitting, and the ratchet wheel 17 can be freely rotated through the bearing 25 in the tubular portion 2a formed in the fitting fitting fixing portion. Since they are supported by the crankshaft 5, the accuracy of concentricity between the crankshaft 5 and the ratchet wheel 17 is improved.

(6) Furthermore, the tip of the rotary shaft 21 of the pinion gear 20 is
Since it is supported by the case lid 3 of the starter case 2, it is possible to prevent the pinion gear 20 from swinging when the starter is started.

[Brief description of drawings]

FIG. 1 is a partial vertical sectional view of a small-sized general-purpose engine to which the present invention is applied, and FIG. 2 is a vertical sectional partial view of a conventional example. 1 ... Crank case, 2 ... Starter case, 2a ... Tube part, 3
…… Case lid, 5 …… Crank shaft, 7 …… Starter motor, 8 …… Clutch wheel, 15,16 …… Ratchet claw, ratchet tooth, 17 …… Ratchet wheel, 17a…
… Boss part, 18 …… Ring gear, 20 …… Pinion gear, 21
……Axis of rotation

Claims (1)

(57) [Scope of utility model registration request] 1. A starter ring gear (18) formed on a ratchet wheel (17) is constantly meshed with a pinion gear (20) of a starter motor (7), and a clutch wheel (8) is attached to a tip portion of a crankshaft (5). ) Boss part (8a) is taper-fitted and fixed, and a ratchet mechanism that transmits the rotation of the starter motor (7) only from the ratchet wheel side to the clutch wheel side is provided between the ratchet wheel (17) and the clutch wheel (8). In a small general-purpose engine starter structure interposed, a boss portion which is formed at an end of the crankcase (1) in the crankshaft direction, and which has an inner peripheral surface for supporting the crankshaft and an outer peripheral anchor portion coaxial with the crankshaft. It has a cylindrical portion (2a) which is fitted and fixed to the boss portion of the boss portion and which surrounds the outer circumference of the crankshaft end portion with the same axis as the crankshaft core. A starter case (2) and a case lid (3) fixed to the starter case (2) are provided, and the tip of the rotary shaft (21) of the pinion gear (20) is supported by the case lid (3). The boss (17a) of the ratchet wheel (17) is rotatably supported by the tubular portion (2a) of the starter case (2) via a bearing (25), and the starter for a small general-purpose engine is characterized by Construction.