JP2001082250A - Automatic choke device for carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate an unsatisfactory situation such that a start becomes difficult due to a fully opened choke valve caused when a long time has passed after an electric-heat valve opening mechanism started an operation. SOLUTION: An electric-heat valve opening mechanism 7 and a complete explosion valve opening mechanism 12 are actuated to a valve stem 6 of a choke valve. A choke lever 26 fastened to the valve stem 6 is provided with an engaging part 28 and a stop part 29, between which a push piece 19 of a complete explosion lever 18 rotatably supported by the valve stem 6 is placed. The stop part 29 strikes the push piece 19 and keeps the choke valve in a semi-choked state using the complete explosion lever 18 in an inoperable position as a stopper, thus making a start easy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic choke device for a carburetor, and more particularly, to an electrothermal valve opening mechanism for gradually opening a choke valve with a rise in temperature, and a choke by suction negative pressure when the engine is completely exploded. The present invention relates to an automatic choke device having a complete explosion opening mechanism that operates to open a valve to a certain opening.

[0002]

2. Description of the Related Art In a carburetor, which is one of fuel supply means for an engine, a generally bimetallic electrothermal valve opening mechanism which operates to gradually open from a fully closed state to a fully opened state with a rise in temperature due to electric resistance heat; In general, a diaphragm-type complete explosion opening valve mechanism, which works to open from fully closed to a certain fully open state due to the high suction negative pressure generated when the engine completely explodes, acts on the choke valve to ensure good startability at low temperatures. It is well known that this is achieved.

FIGS. 3 and 4 show a choke valve 4 of a carburetor for a general-purpose engine in which a fuel container 3 forming a floating constant fuel chamber is disposed below a carburetor main body 1 having an intake passage 2 provided sideways.
FIG. 3 is a diagram showing an example equipped with an automatic choke device having the above-described electrothermal valve opening mechanism 7 and complete explosion valve opening mechanism 12. The choke valve 4 is butterfly-shaped and has a valve shaft 6 to which a valve plate 5 is mounted.
Has one end protruding above the vaporizer main body 1.

The electric valve opening mechanism 7 has a housing 8 having a plate-like heating element 9 generally made of PCT and a spiral bimetal 10 arranged close to the heating element 9.
Is connected to the shaft end of the valve shaft 6 by a link 11, and the heating element 9 is energized to generate electric resistance heat to heat the bimetal 10, and the tip of the bimetal 10 is tightened in the tightening direction. The link 11 is rotated by the deflection to rotate the valve shaft 6 integrally.

[0005] Further, the complete explosion valve opening mechanism 12 comprises a diaphragm 1.
Negative pressure chamber 1 into which one side of engine 3 is introduced with the engine negative pressure
4, a return spring 15 is inserted, and a diaphragm rod 16 projecting from the opposite side and a complete explosion lever 18 rotatably fitted and supported on the valve shaft 6 are connected by a complete explosion arm 17, and the engine The high suction negative pressure generated by the complete explosion sucks the diaphragm 13 and deflects toward the negative pressure chamber 14, whereby the complete explosion arm 17 pulls and rotates the complete explosion lever 18 and is fixedly mounted on the valve shaft 6. When the complete explosion lever 18 pushes the choke lever 21 that is being driven, the valve shaft 6 is rotated.

The complete explosion lever 18 has a flat plate shape and has a pushing piece 19 formed at one end thereof by bending at a right angle. The choke lever 21 is formed such that one end of the elongated plate member is bent into a hook shape to form a mounting portion 22 and the other end extending linearly is an engaging portion 23, and the mounting portion 22 is fitted to the valve shaft 6 from the outside. The valve shaft 6 is fixed by a set screw 20, and the valve shaft 6 is rotated in the opening direction by the pressing portion piece 19 hitting the engaging portion 23 and pressing. Such a structure of the choke lever 21 and an engagement relationship with the complete explosion lever 18 are suitable for a carburetor for a general-purpose engine which requires a small and simple structure.

[0007]

The heating element 9 of the electrothermal valve opening mechanism 7 is often energized using the same wiring as a fuel cutoff solenoid valve operated in response to the operation / stop of the engine. When the switch is turned on to start the engine operation, the heating element 9
0 is started to open the choke valve 4. Therefore, if the engine is left without being started, the choke valve 4 is fully opened after a certain period of time. In addition, when starting without leaving it after the start of energization, if starting is failed and cranking is repeated, during that time, the opening of the choke valve 4 becomes large and starting becomes more difficult. is there.

As described above, when the switch is turned on for the purpose of starting the engine operation, the choke valve 4 is fully opened after a certain period of time irrespective of whether or not the engine is actually started. In order to solve the above-mentioned problem, there is a method in which a relay is provided in a power supply circuit of the heating element 9 or a power supply circuit is connected to a charging circuit. However, wiring becomes complicated and manufacturing costs increase. Therefore, it is difficult to say that it is suitable for a carburetor that is required to be small in size, simple in structure, and inexpensive, such as a carburetor for a general-purpose engine.

According to the present invention, the choke valve is provided with an electric heating when the engine is started for the purpose of starting operation of the engine and the engine is left without starting the engine or when cranking is repeated due to failure of the engine immediately after the engine is started. It is intended to solve the above-mentioned problem that starting is extremely difficult because the valve is fully opened by a valve opening mechanism,
It is an object of the present invention to obtain a good startability even when the choke valve is opened only by the electrothermal valve opening mechanism without operating the complete explosion valve opening mechanism.

[0010]

SUMMARY OF THE INVENTION The present invention provides an electrothermal valve opening mechanism for opening a choke valve from fully closed to fully open by electric resistance heat, and a complete explosion lever rotatably supported on a valve shaft of the choke valve. A complete explosion opening valve mechanism which operates by the suction negative pressure when the engine completely explodes and rotates the complete explosion lever, and which is fixed to the valve shaft and pushed by the complete explosion lever to completely close the choke valve from a certain point. An automatic choke device for a carburetor having a choke lever that rotates so as to open to an opening degree is to solve the above problem as follows.

That is, when the choke valve starts to be opened by the electrothermal valve opening mechanism in a state where the complete explosion valve opening mechanism does not operate, the stop portion which hits the complete explosion lever at a certain opening angle and prevents further opening operation is provided. Provided on the shaft.

Thus, the complete explosion lever has a function of preventing the choke valve from being greatly opened when the engine is not completely exploded, in addition to a function of opening the choke valve when the engine is completely exploded. Good startability can be obtained even after a long time has elapsed since the start of energization.

The choke lever is formed by bending an elongated plate member at the center to form a U-shape. At both ends of the choke lever, the center is fixed to the valve stem at a position where the push piece is sandwiched, and one of both ends is used as the push piece. It is preferable that the engaging portion is a pressed portion and the other is a stopping portion that stops by hitting the pressing piece.

As described above, the wiring of the electrothermal valve opening mechanism is not complicated, and in addition to this, the number of parts is not increased. An excellent carburetor is provided.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 and 2. In this embodiment, an intake passage 2 is provided in a lateral direction similarly to the conventional example shown in FIGS. This is a carburetor for an engine in which a fuel container 3 forming a floating constant fuel chamber is disposed below the carburetor main body 1, and upward of the carburetor main body 1 on a valve shaft 6 to which a valve plate 5 of a choke valve 4 is attached. An electrothermal valve opening mechanism 7 and a complete explosion valve opening mechanism 12 act on the protruding one end.

The electrothermal valve opening mechanism 7 includes a plate-shaped heating element 9 made of PCT and a spiral-shaped bimetal 1 arranged close to the heating element 9.
0 is housed in the housing 8, and the tip of the bimetal 10 and the shaft end of the valve shaft 6 are connected by a link 11.
Electricity is applied to the heating element 9 to generate electric resistance heat, and the bimetal 1
0 is heated, and the tip of the bimetal 10 is displaced in the tightening direction, so that the link 11 rotates and the valve shaft 6 is integrally rotated, and the choke valve 4 is opened from fully closed to fully open.

The complete explosion opening mechanism 12 is provided with a negative pressure chamber 14 on one side of a diaphragm 13 for introducing a negative suction pressure of an engine, and is equipped with a return spring 15 and a diaphragm rod 16 protruding from the opposite side. A complete explosion lever 17 rotatably fitted and supported on the valve shaft 6 is connected by a complete explosion arm 17, and the high suction negative pressure generated by the complete explosion of the engine overcomes the spring force of the return spring 15 and the diaphragm 13. Is deflected by suction toward the negative pressure chamber 14 so that the
Rotates the valve shaft 6 by pulling and rotating the complete explosion lever 18 and pushing the choke lever 26 fixedly mounted on the valve shaft 6 by the complete explosion lever 18 to rotate the choke valve 4 from fully closed to a certain opening. Let it open.

The complete explosion lever 18 is flat and has a push piece 19 formed at one end thereof by bending at a right angle. Further, the choke lever 26 is formed in a U-shape obtained by bending an elongated plate member at a central portion, and a bent portion is an attachment portion 27, one end portion extending linearly is an engagement portion 28, and the other end portion is a stop portion 29. I have.

The choke lever 26 is mounted on the mounting portion 27 at a position where the engaging portion 28 and the stop portion 29 sandwich the pressing piece 19.
Is fitted to the valve shaft 6 from the outside, and is fixed by the set screw 20. When the electrothermal valve opening mechanism 7 does not start to open the choke valve 4 or when the complete explosion opening valve mechanism 12 is operated in a slightly open state, Push piece 1 by rotation of complete explosion lever 18
9 touches the engaging portion 28 and pushes it to open the choke valve 4 at a position where it is balanced with the load of the bimetal 10. When the choke valve 4 is opened by the electrothermal valve opening mechanism 7 without operating the complete explosion valve opening mechanism 12, the stop part 29 hits the push part 19 when a certain opening angle is reached, and the push part 19
Acts as a stopper to prevent the choke valve 4 from opening further, thereby maintaining a state in which the choke valve 4 can be easily started.

If the engine is stopped while the choke valve 4 is at a certain opening angle by the stop portion 29 hitting the push portion 19, the complete explosion opening valve mechanism 12 is inoperative and the complete explosion opening mechanism 12 is completely stopped by the spring force of the return spring 15. The explosion lever 18 rotates in the opposite direction. For this reason, an advantageous state is created when the push piece 19 pushes the stop portion 29 to close the choke valve 4 to a position where the load of the bimetal 10 and the spring force of the return spring 15 are balanced, and restart immediately thereafter.

The stop portion 29 may be formed as a separate component from the choke lever 26 and fixedly protruded from the valve shaft 6. However, if the stop portion 29 is formed integrally with the choke lever 26 as in the illustrated embodiment,
There is no increase in the number of parts and no increase in the number of steps for assembling the valve shaft 6, and it is possible to meet the demand for compactness, simple structure, and low cost equivalent to those of the conventional example shown in FIGS.

FIGS. 5 and 6 are explanatory diagrams for comparing the operation of the embodiment of the present invention with that of the conventional example. FIG. 5 shows a state in which a certain time elapses after the electrothermal valve opening mechanism 7 starts operating. FIG. 6 shows a case where the normal operation procedure of starting immediately after the start of operation of the electrothermal valve opening mechanism 7 is followed.

First, in FIG. 5, (A-1) and (B-
1) shows a state in which both the electrothermal valve opening mechanism 7 and the complete explosion valve opening mechanism 12 are not operating. The choke valve 4 is located at the fully closed position, and the engaging portion of the choke lever 26 in the present embodiment. The stop portion 29, the engaging portion 23 of the choke lever 21 in the conventional example, and the engaging portion 23 of the choke lever 21 are all slightly away from the pushing portion 19 of the complete explosion lever 18. When the switch is turned on for engine operation, the electrothermal valve opening mechanism 7 starts operating,
If you leave the engine without actually starting it,
In the conventional example, the choke valve 4 is fully opened as shown in (B-2), whereas in the present embodiment, the stop portion 29 hits the push piece 19 as shown in (A-2), so that the choke valve 4 is opened. 4 is held at a certain opening angle.

When the complete explosion valve opening mechanism 12 is operated by starting the engine at this position, the complete explosion lever 18 rotates counterclockwise in the drawing, and in the present embodiment, a half-choke state with a certain opening angle is established. The choke valve 4 follows the complete explosion lever 18 by the bimetallic load of the electrothermal valve opening mechanism 7 and is instantaneously fully opened to the state shown in (A-3). At this time, the push piece 19 is hit by the stop 29 and the choke 4
Works as a fully open stopper. In the conventional example, since the choke valve 4 has already been fully opened, the complete explosion lever 18 idles and becomes a state shown in (B-3). That is, according to the present embodiment, even when a long time has elapsed since the start of the operation of the electrothermal valve opening mechanism 7, an easy and reliable start in a semi-choke state can be obtained. The electric valve opening mechanism 7
If the engine is started immediately after the start of the operation, (A-2), (B)
It is easily understood that the present embodiment in which the half-choke state is maintained even in the state shown in -2) is easier to start successfully.

When the engine operating in the state shown in (A-3) or (B-3) is stopped, the temperature of the electrothermal valve opening mechanism 7 gradually decreases and the choke valve 4 is fully closed little by little. The complete explosion valve opening mechanism 12 returns to the inoperative position at once. In the present embodiment, when the complete explosion lever 18 rotates clockwise in the figure, the push piece 19 pushes the stop part 29 to rotate the valve shaft 6 in the valve closing direction, and the load of the bimetal 10 and the spring force of the return spring 15 The choke valve 4 is returned to a position where is balanced, and the state shown in (A-4) is reached. For this reason,
When the restart is performed immediately after the stop, the restart can be easily and surely performed in the half-choke state similar to (A-2). In the conventional example, as shown in (B-4), the restart immediately after the engine is stopped, in which the choke valve 4 is fully open, is performed in the same state as in (B-2). .

When the engine is stopped and left without restarting, the temperature of the electrothermal valve opening mechanism 7 causes the choke valve 4 to return to the fully closed position shown in (A-1) and (B-1). .

Next, in FIG. 6, (A-1) and (B-
1) shows a state in which both the electrothermal valve opening mechanism 7 and the complete explosion valve opening mechanism 12 are not operating, and (A-1) and (B) in FIG.
Same as -1). When the switch is turned on for the operation of the engine, the electrothermal valve opening mechanism 7 starts to operate. Immediately after that, or when the engine is started before the choke valve 4 is largely opened, the complete explosion valve opening mechanism 12 operates to complete the operation. Explosive lever 1
8 presses the engaging portions 23 and 28 of the choke levers 21 and 26 to load the bimetal 10 and the return spring 1.
The choke valve 4 is opened at a position where the spring force 5 is balanced, and a half-choke state shown in (A-2) and (B-2) is obtained.

Thus, the electrothermal valve opening mechanism 7 opens the choke valve 4 until it is fully opened, and normal engine operation is performed in the state shown in (A-3) and (B-3).

When the engine operating in the state shown in (A-3) or (B-3) is stopped, the temperature of the electrothermal valve opening mechanism 7 gradually decreases, and the choke valve 4 is fully closed little by little. The complete explosion valve opening mechanism 12 returns to the inoperative position at once. In the present embodiment, when the complete explosion lever 18 rotates clockwise in the figure, the pushing part 19 pushes the stop piece 29 to place the choke valve 4 at a position where the load of the bimetal 10 and the spring force of the return spring 15 are balanced. Return to the semi-choke state shown in (A-4), and make it easy and reliable to restart immediately after. In the conventional example, as shown in (B-4), the restart immediately after is performed with the choke valve 4 fully opened, which are the same as (A-4) and (B-4) in FIG.

If the engine is stopped and left without restarting, the choke valve 4 returns to the fully closed position shown in (A-1) and (B-1) due to the temperature drop of the electrothermal valve opening mechanism 7.

As described above, according to the present embodiment, even after a long period of time has elapsed since the operation of the electrothermal valve opening mechanism 7 started, the stop portion 29 hits the push piece 19 and the half-choke state is established. The start can be easily and surely performed because of the maintenance, and the push piece 19 can be operated even when the operation is stopped.
Presses the stop portion 29 to be in a half-choke state, so that the restart immediately after can be easily and reliably performed.

[0032]

As described above, even if the switch is turned on to start the engine operation and the electrothermal valve opening mechanism starts operating at the same time, the switch is turned on and left as it is. In such a case, the engine can be easily and reliably started by maintaining the choke valve in a half-choke state without fully opening it, and in addition, restarting immediately after the engine is stopped can be easily and reliably performed in the half-choke state. It is. Also, when the member that maintains the half-choke state is integrated with the choke lever, there is no increase in the number of parts.
The requirement of simple structure and low cost can be satisfied.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention when a choke valve is fully opened.

FIG. 2 is an enlarged sectional view taken along line AA of FIG.

FIG. 3 is a longitudinal sectional view showing a conventional example when a choke valve is fully opened.

FIG. 4 is an enlarged sectional view taken along line BB of FIG. 3;

FIG. 5 is a diagram illustrating an operation comparison between the embodiment of the present invention and a conventional example.

FIG. 6 is an explanatory diagram illustrating another operation comparison between the embodiment of the present invention and a conventional example.

[Explanation of symbols]

4 choke valve, 6 valve shaft, 7 electrothermal valve opening mechanism, 12
Complete explosion opening mechanism, 18 Complete explosion lever, 19 Push piece, 26
Choke lever, 28 engaging part, 29 stopping part,

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiromasa Ohno 3029 Uechi, Atsugi-shi, Kanagawa Prefecture Inside Nippon Kayoke Mfg. Co., Ltd. Terms (reference) 3G006 AA01 BB01 BB12 BB25 BB32 BC03 BC07

Claims (2)

[Claims] 1. An engine having an electrothermal valve opening mechanism for opening a choke valve from fully closed to fully open by electric resistance heat, and a complete explosion lever rotatably supported on a valve shaft of the choke valve. A complete explosion opening valve mechanism that operates by the suction negative pressure when the explosion operates and rotates the complete explosion lever; a complete explosion valve that is fixed to the valve shaft and pushed by the complete explosion lever to fully close the choke valve to a certain opening degree An automatic choke device for a carburetor having a choke lever rotating so as to open, when the choke valve starts opening by the electrothermal valve opening mechanism in a state where the complete explosion valve opening mechanism is not operated, a certain opening An automatic choke device, wherein a stop portion is provided on the valve shaft to prevent the further opening operation by hitting the complete explosion lever at an angle. 2. The choke lever is formed in a U-shape obtained by bending an elongated plate member at a central portion, and the central portion is connected to the valve shaft at a position where both ends sandwich a pressing piece provided on the complete explosion lever. One end of the both ends is an engagement portion that is pushed by the pushing piece to rotate the choke valve from fully closed to a certain opening degree, and the other is the pushing piece. 2. The automatic choke device for a carburetor according to claim 1, wherein the stop portion prevents the further opening operation during the operation.