JPH088293Y2 - Auto choke carburetor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an auto choke carburetor that opens and closes a choke valve with a bimetal.

[Prior Art] An auto choke type carburetor that automatically opens and closes a choke valve by using a bimetal that deforms by sensing the temperature and warm-up conditions of the engine is easy to handle as the heating method that deforms the bimetal conventionally. For this reason, a method has been adopted in which the battery is used as a power source to energize the electric heater and the heat of the electric heater is added to the bimetal for heating.

[Problems to be Solved by the Invention] However, in the case of the heating method using a battery as a power source, there is a problem that the bimetal cannot be heated in a small engine without a battery because there is no battery.

It is an object of the present invention to provide an auto choke type carburetor capable of heating a bimetal even in an engine without a battery.

[Means for Solving the Problems] To explain the configuration of the present invention for achieving the above object, the present invention is designed so that a choke valve for controlling an air amount of an air-fuel mixture supplied to an engine is opened and closed by a bimetal. In an auto choke type carburetor, a magnet generator attached to the engine is used as a power source for heating the bimetal, and the magnet generator includes a primary coil for engine ignition incorporated therein. A reverse-polarity half-wave extraction circuit for extracting a reverse-polarity half-wave having a polarity opposite to that of the engine ignition half-wave out of the AC output and energizing the heating source of the bimetal is connected.

[Operation] In the AC output of the primary coil for engine ignition in the magnet generator, only one half-wave is used as the half-wave for engine ignition, and the polarity is opposite to that of the half-wave for engine ignition. Since the reverse polarity half-wave is not used, this reverse polarity half-wave is supplied to the bimetal heating source. When the bimetal is heated in this way, the bimetal is deformed and the choke valve is opened. Further, when the magnet generator is used as the heating power source, it is possible to heat the bimetal even in a small engine without a battery. In particular, when a bimetal heating source is energized by using a reverse polarity half wave having a polarity opposite to that of the engine ignition half wave among the AC output of the engine ignition primary coil as in the present invention, the bimetal is generated in the magnet generator. Since it is not necessary to incorporate a special power generation coil for energization, it can be implemented at low cost.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

1 to 3 show a first embodiment of an auto choke type carburetor according to the present invention.

As shown in the drawing, in the auto-choke type carburetor of this embodiment, a choke valve 3 is supported by a choke valve drive shaft 4 and is rotatably arranged in an air supply pipe 2 for feeding air to the carburetor body 1. A bimetal mounting plate 5 is supported on the carburetor body 1. A bimetal case 6 having a heat retaining property is attached to the bimetal mounting plate 5. A mainspring-shaped bimetal 7 is housed in the bimetal case 6. The center side end of the bimetal 7 is supported by a metal bimetal support shaft 8. The base end of the bimetal support shaft 8 is supported by the bimetal case 6 via an insulator 9. One end of the bimetal lever 10 is attached to the outer end of the bimetal case 6,
The other end of the bimetal lever 10 has a bimetal lever shaft 11
One end of is attached. The other end of the bimetal lever shaft 11 is connected to the choke valve drive shaft 4 via a lever 12, a link 13 and a lever 14. In this case, link 13
One end of the link 13 is connected to the lever 12 by passing it through the lever 12, and the other end of the link 13 is connected to the lever 14 by a connecting pin 15.

A vacuum pump 16 is attached to the bimetal attachment plate 5. The inside of the vacuum pump 16 is partitioned by a diaphragm 17. The Venturi part of the carburetor body 1 and the vacuum pump 16 are rubber pipes for boosting 18
The negative pressure generated in the Venturi portion acts on the diaphragm 17. The displacement of the diaphragm 17 is transmitted to the choke valve drive shaft 4 via the arm 19, the link 20, and the lever 21. In this case, the arm 19 is attached to the diaphragm 17 and the link 20
One end of the link 20 is connected by passing through the arm 19, and the other end of the link 20 is connected by passing through a lever 21.

An engine (not shown) to which the air-fuel mixture is supplied from the carburetor body 1 is equipped with a magnet generator 22 which is driven by its rotational output to generate electric power. In the magnet generator 22, an engine ignition primary coil 23 and an engine ignition secondary coil 24 magnetically coupled thereto are incorporated. Normally, one end of the primary coil 23 has one half of the AC output 28 from the primary coil 23, which is a half wave for engine ignition.
Ignition circuit unit 25 that takes out 28A and starts the ignition operation of the engine and stop switch 26 that stops the operation
Are connected to each other, and the other ends thereof are grounded. The other end of the primary coil 23 is grounded.
One end of the spark plug 27 is connected to one end of the secondary coil 24, and the other end of the secondary coil 24 and the other end of the spark plug 27 are grounded.

In particular, in the present embodiment, the bipolar metal 7 is directly energized by utilizing the reverse polarity half-wave 28B having the opposite polarity to the engine ignition half-wave 28A of the AC output 28 output from the primary coil 23. At one end of the primary coil 23, the center side end of the mainspring bimetal 7 has a reverse polarity half-wave extraction circuit 29.
And electrically connected via the bimetal support shaft 8. The reverse polarity half-wave extraction circuit 29 includes a lead wire 30 that connects one end of the primary coil 23 and an end of the bimetal 7 on the center side.
And a rectifier consisting of a diode connected in series to the lead wire 30 with the anode side facing the one end side of the primary coil 23.
It consists of 31 and. The outer end of the bimetal 7 has a bimetal lever 10, a bimetal lever shaft 11, a lever 12, and a link 1.
3, grounded via a connecting pin 15, a lever 14, a choke valve drive shaft 4, an air supply pipe 2 and the like. That is, in this embodiment, the bimetal 7 itself also serves as its heating source.

In such an auto choke type carburetor, the choke valve 3 is closed by the bimetal 7 that senses the ambient temperature at the time of starting before the engine operation where the outside temperature is low.
For this reason, the carburetor supplies a rich air-fuel mixture for starting, so that the engine can be started.

When the engine is started, the magnet generator 22 attached to the engine starts power generation, and the engine ignition half-wave 28 of the AC output 28 from the engine ignition primary coil 23 is generated.
Reverse polarity half-wave with reverse polarity to A 28B is reverse polarity half-wave extraction circuit
It is taken out via 29 and the bimetal 7 is directly energized. As a result, the bimetal 7 is self-heated and deformed, and the deforming force is transmitted to the bimetal lever 10, the bimetal lever shaft 11, the lever 12, the link 13, the connecting pin 15, the lever 14 and the choke valve drive shaft 4 to drive the choke valve. The rotation of the shaft 4 opens the choke valve 3.

Further, a negative pressure is generated in the venturi portion of the carburetor main body 1 when the engine is started, and the negative pressure is the vacuum pump.
Acting on the 16 diaphragms 17, the displacement of the diaphragm 17 is transmitted to the arm 19, the link 20, the lever 21, and the choke valve drive shaft 4, and the choke valve 3 is opened even by the force based on this negative pressure. That is, the operation of the vacuum pump 16
When the engine is started, it responds quickly, promotes the opening movement of the choke valve 3, and prevents excessive fuel supply to the engine.

When the engine stops, the heating of the bimetal 7 and the operation of the vacuum pump 16 also stop, but the bimetal case 6
Since the bimetal 7 maintains a warmed state due to the heat retaining property of, the choke valve 3 also keeps the opened state for a while. Therefore, it is possible to easily restart the engine even when the engine is warmed up without causing excessive fuel supply.

4 and 5 show a second embodiment of the auto choke type carburetor according to the present invention. In this embodiment, an electric heater 32 is provided in the bimetal case 6 as a heating source for the bimetal 7, and the electric heater 32 is attached to the bimetal support shaft 8 so as to face the bimetal 7. One end of the electric heater 32 is connected to one end of the engine ignition primary coil 23 via the rectifier 31, and the other end of the electric heater 32 is grounded via the bimetal support shaft 8 and the bimetal case 6. In this case, the bimetal support shaft 8 is supported by the bimetal case 6 without being electrically insulated.

Even with such a structure, even in the case of a small engine not equipped with a battery as in the first embodiment, the bimetal 7 can be easily formed.
Can be heated.

[Effects of the Invention] As described above, in the auto choke type carburetor according to the present invention, the magnet generator is used as the power source for heating the bimetal, so that the bimetal can be easily heated even in a small engine without a battery. be able to.
Particularly, in the present invention, of the AC output of the primary coil for engine ignition, a reverse polarity half wave having a polarity opposite to that of the engine ignition half wave is extracted by the reverse polarity half wave extraction circuit to energize the bimetal heating source. Since it is not necessary to incorporate a special magneto coil for energizing the bimetal in the magnet generator, it can be implemented at low cost.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first embodiment of an auto choke type carburetor according to the present invention, and FIG. 2 is a partially longitudinal side view of a first embodiment of the auto choke type carburetor of the first embodiment.
FIG. 4 is an AC output waveform diagram of a primary coil for engine ignition used in this embodiment, FIG. 4 is a circuit diagram of a second embodiment of an auto choke type carburetor according to the present invention, and FIG. 5 is the second embodiment. It is a partial longitudinal side view of the example auto-choke type carburetor. 1 ... Carburetor body, 2 ... Air pipe, 3 ... Choke valve, 4 ... Choke valve drive shaft, 5 ... Bimetal mounting plate, 6 ... Bimetal case, 7 ... Mainspring bimetal, 8 ... Bimetal Support shaft, 9 ... Insulator, 10
…… Bimetal lever, 11 …… Bimetal lever shaft, 12
...... Lever, 13 ...... Link, 14 …… Lever, 15 …… Connecting pin, 16 …… Vacuum pump, 17 …… Diaphragm,
18 …… boost rubber pipe, 19 …… arm, 20 …… link, 21 …… lever, 22 …… magnet generator, 23 …… engine ignition primary coil, 24 …… engine ignition secondary coil, 25 ...... Ignition circuit unit, 26 ...... Stop switch, 27 ...... Ignition plug, 28 ...... AC output, 28A ...... Engine ignition half wave, 28B ...... Reverse polarity half wave, 29 ...... Reverse polarity half wave extraction circuit , 30 …… lead wire, 31 …… rectifier, 32 ……
Electric heater.

Claims (1)

[Scope of utility model registration request] 1. An auto choke type carburetor in which a choke valve for controlling the amount of air-fuel mixture supplied to an engine is opened and closed by a bimetal, which is attached to the engine as a power source for heating the bimetal. A magnet generator is used, and a reverse polarity half-wave having a polarity opposite to that of the engine ignition half-wave is taken out from the AC output of the engine ignition primary coil built in the magnet generator. An auto choke carburetor characterized in that a reverse-polarity half-wave extraction circuit for energizing a bimetal heating source is connected.