JPS6131307B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to a kick-type or other input-type starting device for a two-stroke, single-cylinder engine in a motorcycle or other two-wheeled vehicle.

Conventionally, this type of device is known in which the engine is started by rotating the engine crankshaft using a kick force or other human power, but in this case, the starting load, in other words, In this case, there is a need to reduce the kicking force as much as possible.

The object of the present invention is to obtain a device that meets such requirements, and in a device that starts the engine by rotating the crankshaft of the engine by input, the crankshaft is provided with a device that rotates in the normal direction. It is equipped with a one-way clutch-type non-return mechanism that allows the engine to move forward but prevents reverse rotation. It is made to stop and stop.

Embodiments of the present invention will be described with reference to attached drawings.

The drawing shows the case of a unit swing type motorcycle, where 1 is a two-stroke single-cylinder engine, 2 is the cylinder, 3 is the piston inside, 4 is the crankshaft, and 5 is the connecting rod in the middle. A transmission case 6 extending rearward is provided on one side of the engine 1. The case 6 extends to the side surface of the rear wheel 7 behind it and pivotally supports the axle 8 of the vehicle 7, and has a chain or other power transmission mechanism inside thereof that connects the wheel 7 to the output side of the crankshaft 4. 9 so that the swing unit is formed by the case 6. The crankshaft 4
is equipped with an automatic centrifugal clutch 10 at its outer end, and the output side of the clutch 10 is connected to the wheel 7 via the transmission mechanism 9. The engine 1 is made of a two-stroke type as described above, and has a scavenging port 11 and an exhaust port 12 on the side surface of the cylinder 2, and the compression stroke d of the piston 3 is located above the exhaust port 12. was made to exist. Bearings 13, 13 on both sides that pivotally support the crankshaft 4
was used in ball bearings and other rolling bearings to reduce rotational resistance.

A starting shaft 14 that is manually rotated is provided in the middle part of the transmission case 6, and in the illustrated example, this is a kick shaft having a kick arm 15 at the outer end.
This is connected to an operating shaft 19 in front of it via a speed increasing mechanism 18 consisting of a gear mechanism 16 and a chain mechanism 17, and the operating shaft 19 is further connected to a one-way clutch 2.
The clutch shaft 14 is connected to the above-mentioned crankshaft 4 through the clutch shaft 4, so that when the starting shaft 14 rotates, the rotation speed is increased and transmitted to the clutch shaft 4, so that the engine 1 can be started.

The one-way clutch 20 is, for example, a ratchet gear 20 on the operating shaft 19 side, as shown clearly in FIG.
a, and a drive plate 10a on the clutch shaft 4 side, i.e. on the input side of the automatic centrifugal clutch 10 on said shaft 4.
The starting shaft 14 is normally in the initial position where the starting shaft 14 is reversed by the return spring 14a and stopped by the stopper, and accordingly the ratchet gear 20a is at the angular position shown. The gear 20a is fixed to the pawl 20.
In cooperation with b, the clutch shaft 4 functions as a check mechanism for the clutch shaft 4, that is, a mechanism that allows forward rotation but prevents reverse rotation.

The non-return position, that is, the angular position where the ratchet pawl 20b and the ratchet gear 20a engage to prevent the crankshaft 4 from reversing, is 50±10 degrees above top dead center, i.e. 40~ The angle shall be 60 degrees. In other words, the piston 3 connected to the crankshaft 4 is at an angular position in the middle of the compression stroke. The one-way clutch 20 is not limited to this ratchet type, but for example, as shown in the third figure, it consists of an inner rotor 20c and an outer rotor 20d, with an inclined ball groove 20e in the middle, and a ball 20f connected to the spring 20g. It is also conceivable to use a type that allows the ball to be repelled and accommodated. To explain its operation in the case of the ratchet type, engine 1
In order to start the engine, a manual force such as a jerk force is applied to the starting shaft 14 to give it rotation, and this rotation is accelerated and acts on the crankshaft 4 via the one-way clutch 20 to rotate it. , thus the engine 1 is started. Next, considering when the engine 1 stops operating, the engine 1 comes to a stop with the piston 3 in the middle of the compression stroke. More specifically, the piston 3 rises to a position 10 to 30 degrees before top dead center, is stopped by compression pressure, and then is pushed back more or less. At this time, the one-way clutch 20 acts to prevent this from happening, that is, for example, as shown in FIG.
0b engages with the ratchet gear 20a to stop the crankshaft 4 in that angular position. At this time, the above-mentioned compressive force is then gradually released from the clearance of the piston ring around the outer periphery of the piston 3 and decreases.

Next, when the starting shaft 14 is rotated to start the engine 1, the crankshaft 4 starts rotating from the above-mentioned check position, and in the first compression stroke, the compression stroke of the piston 3 is normal. It is shorter than in the case of , and as mentioned above, the previous compression pressure is released, so the rotation is extremely light, in other words, the starting load is about 1/3 to 1/4 of the normal load.
The shaft 4 then moves to the second compression stroke, but at this time, the angular velocity of the shaft 4 has already increased, so its inertia overcomes the compression pressure and increases the starting load. Therefore, the starting load as a whole is larger than that of the conventional one, for example, 30 to 50
% will be reduced.

According to the inventor's experiments, the relationship between the set position of the piston 3 at the start of startup and the kick load is as shown in FIG. 4, for example, and the set position is before top dead center.
It was confirmed that the stiff load was relatively small between 40 and 60 degrees.

According to the present invention, when the engine is stopped, the crankshaft is stopped at the angular position where the piston is in the middle of the compression stroke in preparation for the next start, and the starting load can be significantly reduced. This has the effect of making starting simple and easy.

[Brief explanation of the drawing]

FIG. 1 is a cutaway side view of the essential parts of an example of a motorcycle equipped with the device of the present invention, FIG. 2 is a cutaway plan view thereof,
FIG. 3 is a cross-sectional side view of a portion of the modified example, and FIG. 4 is a characteristic diagram of the harsh load. 1...Engine, 3...Piston, 4...Crankshaft, 14...Starting shaft, 20...One-way clutch,
20a...Ratchet gear, 20b...Ratchet pawl.

Claims (1)

[Claims] 1. In an engine that starts the engine by rotating the crankshaft of the engine through input, a one-way clutch-type check mechanism is provided on the crankshaft that allows forward rotation but prevents reverse rotation. An engine starting device comprising: when stopping the operation of the engine, the crankshaft is reverse-checked and stopped by the mechanism at an angular position where the piston connected to the crankshaft is in the middle of the compression stroke. 2. The check mechanism has a ratchet type structure consisting of a ratchet gear and a ratchet pawl that engages with the ratchet gear, and the pawl is configured to check the crankshaft at an angular position of 40 to 60 degrees before top dead center. An engine starting device according to claim 1, wherein the engine starting device is arranged as follows.