JPS6133237Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an autochoke mechanism for a carburetor used in a forced air-cooled engine in which the engine is cooled by a blower fan.

An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes an engine, reference numeral 2 denotes a cover which covers the entire engine and which is provided with an air inlet 5 and an air outlet 6.
This air inlet 5 is connected to the crankshaft 3 of the engine 1.
A blower fan 4 is provided connected to the engine cover 2, which blows air into the cover 2 when the engine is running. A carburetor 7 is attached to the engine 1 and connected to the engine 1 from the outside of the cover 2. A crankcase 8 is connected to the engine cover 2.
9 is an intake passage of the carburetor 7, 9a is a main fuel nozzle, 10
Reference numeral 11 denotes a throttle valve, 12 denotes a pressure plate provided in the air passage from the air inlet 5 to the air outlet 6 in a swingable manner. In the embodiment, the pressure plate 1
2 is disposed at the air outlet 6. Reference numeral 13 denotes a connecting mechanism for connecting the pressure plate 12 and the yoke valve 11 so as to be freely rotatable. In this embodiment, a yoke lever 14 and an operating lever 15 of the pressure plate 12 are connected by a connecting rod 16. Therefore, when the engine is operated and air is blown into the cover 2 by the blower fan 4, the pressure of the air causes the pressure plate 12 to rotate,
The choke valve 11 is rotated via a connecting rod 16. A is the temperature of the choke valve 11 according to the engine temperature.
When the engine 1 is cold, the yoke valve 11 is turned on.
The pressure plate 12 is locked, and the lock is released after the engine 1 is warmed up.

To explain the embodiment of the temperature sensing device A, 17 is a bimetal that expands depending on the temperature of the engine 1;
The base end of this bimetal 17 is fixed to the engine 1 or the cover 2, and the distal end is adapted to engage and disengage from the choke lever 14. This bimetal 17 stretches when the engine temperature is low,
Its tip engages with the check valve 14 to hold the check valve 11 in the closed position. On the other hand, when the engine 1 is warmed up, the bimetal 17 bends and disengages from the choke lever 14.
The yoke valve 11 is rotatable. Further, since the pressure receiving plate 12 rotates integrally with the check valve 11, when the check valve 11 is held in a closed state, the pressure receiving plate 12 is also held in a state in which the air outlet 6 is constricted.

FIG. 3 shows an example in which a thermowax 18 is used as a temperature-sensitive member.To explain below, the thermowax 18 is fixed to the engine 1 or the cover 2,
A locking piece 2 that transmits the change in the volume of the thermowax 18 to the operating rod 19 and is fixed to the tip of the operating rod 19
0, the rotation of the chiyoke valve 11 is restricted.

To explain the function of the automatic engine yoke mechanism configured in this way, when the engine 1 is in a cold state at the time of starting, in the first embodiment, the bimetal 17 is extended, and its tip is extended as shown in FIG. engages with the choke lever 14,
In addition, in the second embodiment, there is no change in the volume of the thermowax 18, and the locking piece 20 at the tip of the operating rod 19 engages with the choke lever 14 as shown in FIG. I'm keeping it.

When the engine 1 is started in this state, even if the wind pressure generated by the blower fan 4 is acting on the pressure receiving plate 12, the chiyork valve 11 closes the intake passage 9, so the chiyork valve 11 closes the intake passage 9. The amount of air flowing in is further restricted, and a strong suction negative pressure of the engine 1 acts on the main fuel nozzle 9a, and a large amount of fuel is ejected from the main nozzle 9a, supplying a rich air-fuel mixture suitable for starting, and starting the engine 1. can smoothly transition to starting operation.

Also, at this time, since the area of the air outlet 6 (air passage) of the cover 2 is narrowed by the pressure receiving plate 12, the amount of cooling air blown into the cover 2 is reduced, and the engine is warmed up quickly. .

As a result, when the temperature of the engine 1 gradually increases, the bimetal 17 in the first embodiment
is bent, and the tip of the bimetal 17 separates from the jaw lever 14. In the case of the second embodiment, the operating rod 19 protrudes due to the expansion of the thermowax 18, and the locking piece 20 at the tip of the operating rod 19 separates from the jaw lever 14. And pressure receiving plate 12
is rotated by the wind pressure of the blower fan 4, and the connecting rod 1
The check valve 11 is opened via 6.

As described above, according to the present invention, in a forced air-cooled engine, a pressure receiving plate provided so as to be rotated by the wind pressure of a blower fan is interlocked and connected to the chiyok valve of the carburetor, and further, the pressure receiving plate is connected in conjunction with the chiyok valve in the opening direction of the chiyok valve. A temperature-sensing device for controlling the timing is provided in conjunction with the chiyok valve, and the chiyok valve is configured to open and close automatically, so that the automatic chiyoke device for the carburetor installed in this type of engine can be constructed with a simple structure. Can be provided.

Further, when the engine is started in a cold state, the pressure receiving plate throttles the air passage for cooling air by the blower fan and reduces the amount of air blown, so that the engine can be warmed up quickly.

In addition, since the wind pressure from the blower fan acts on the pressure receiving plate at the same time as the engine starts, if a slight play (gap) is provided between the chiyoke valve lever and the temperature sensing device, this play will be used after the engine starts. The engine valve opens slightly, diluting the starting air-fuel mixture slightly and allowing smooth warm-up.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing one embodiment of the present invention, Fig. 2 is a partial longitudinal sectional view showing the operating state of Fig. 1, and Fig. 3 is a partial longitudinal sectional view showing another embodiment of the invention. It is. DESCRIPTION OF SYMBOLS 1...Engine, 2...Cover, 4...Blower fan, 7...Chiyoke valve, 12...Pressure plate, 14
...Chiyoke lever, A...Temperature sensing device.

Claims (1)

[Scope of utility model registration request] In a forced air cooling engine, the engine is covered with a cover having an air inlet and an air outlet, and the air inlet includes a blower fan that is linked to the engine, and the air passage from the air inlet to the air outlet is A swingable pressure receiving plate is provided in the engine, the pressure receiving plate is interlocked with the carburetor's choke valve, and a temperature sensing device is provided to lock the choke valve and the pressure plate when the engine is cold. An auto-choke mechanism for a carburetor, characterized in that the ch-yoke valve is kept in a closed state and the pressure receiving plate narrows the area of the air passage.