JPH0735745U - Vaporizer secondary throttle valve opening control mechanism - Google Patents

Abstract

(57) [Abstract] [Purpose] Providing a secondary side throttle valve opening control mechanism for a carburetor capable of performing reliable negative pressure control according to the choke opening without causing a lean fuel mixture ratio. . [Structure] An actuator 8 having an operating pressure of a combined negative pressure of the negative pressures of the primary and secondary venturis 2A and 2B is provided,
A secondary side throttle valve opening control mechanism of a carburetor for controlling the opening degree of the secondary side throttle valve 4B by operating the actuator 8, wherein the operating pressure of the actuator 8 is based on a change in the opening degree of the choke valve 5. Thus, when the choke valve 5 is in the choked state, the opening degree of the secondary throttle valve 4B is adjusted to be smaller than that in the fully opened state.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a secondary side throttle valve opening control mechanism for a carburetor.

[0002]

[Prior art]

 The conventional secondary side throttle valve opening control mechanism of the carburetor will be described with reference to FIG. 7. Inside the main body B of the illustrated carburetor, the primary side intake passage 3A and the secondary side intake passage in parallel therewith are shown. A passage 3B is formed. In the primary intake passage 3A, a large venturi 2A that surrounds a small venturi 1A having an open fuel passage is formed, and a primary throttle valve 4A and a choke valve 5 are arranged. On the other hand, in the secondary side intake passage 3B, a large venturi 2B surrounding a small venturi 1B in which a fuel passage is similarly opened is formed, and a secondary throttle valve 4B is arranged. In such a carburetor, the negative pressure of the large venturi 2A in the primary side intake passage 3A and the negative pressure of the large venturi 2B in the secondary side intake passage 3B are respectively the primary side venturi negative pressure passage 6A and the secondary side venturi. The negative pressure is guided to the negative pressure passage 6B, and these negative pressures are further guided to the secondary valve diaphragm (actuator) 8 via the composite negative pressure passage 7. Here, the opening degree of the secondary side throttle valve 4B is controlled based on the operation of the secondary valve diaphragm 8, that is, the secondary side throttle valve 4B is the negative pressure of the primary side venturi negative pressure passage 6A and the secondary side. The opening degree is controlled in accordance with the negative pressure obtained by combining the negative pressures in the venturi negative pressure passage 6B. By the way, in such a secondary side throttle valve opening control mechanism, when the opening degree of the choke valve 5 changes, the negative pressure of the primary side Venturi negative pressure passage 6A changes accordingly, and as a result, the secondary side throttle valve The opening degree of the valve 4B changes according to the opening degree of the choke valve 5. More specifically, when the choke valve 5 is in a throttled state (hereinafter simply referred to as “choke”), the secondary side throttle valve 4B is compared with its fully opened state. Is increased, that is, the amount of air from the secondary side intake passage 3B is increased, the mixing ratio is decreased, and drivability is deteriorated. Therefore, in the conventional secondary side throttle valve opening control mechanism, the combined negative pressure from the primary side Venturi negative pressure passage 6A and the secondary side Venturi negative pressure passage 6B is passed through the solenoid valve 9 to the secondary valve diaphragm. 8 and the solenoid valve 9 is controlled to open / close by a water temperature switch 10 that operates based on a change in the engine water temperature, and the negative pressure is leaked to the outside or cut off when the choke is made. It is configured to reduce the degree of opening.

[0003]

[Problems to be solved by the device]

 However, the correlation between the engine water temperature and the choke opening is not always constant, and varies depending on the influence of the water temperature at start-up, operating conditions, etc.Therefore, in the negative pressure control based on the engine water temperature as described above, the desired There was a problem that negative pressure control could not be performed at the choke opening.

[0004]

[Means for Solving the Problems]

 The present invention has been devised in view of the above-mentioned conventional problems, and is provided with an actuator whose working pressure is a combined negative pressure of the venturi negative pressures of the primary side and the secondary side. A secondary side throttle valve opening control mechanism for a carburetor that controls the opening degree of the secondary side throttle valve, wherein the operating pressure of the actuator is based on a change in the opening degree of the choke valve and the choke valve is in a choked state. The feature is that adjustment is made so that the opening of the secondary side throttle valve becomes smaller than in the fully open state.

[0005]

[Action]

 In the present invention, the operating pressure of the actuator is based on the change in the opening of the choke valve, and when the choke valve is in the choke state, the opening of the secondary throttle valve is made smaller than that in the fully open state. Can be reliably prevented from becoming thin.

[0006]

【Example】

 Next, a secondary side throttle valve opening control mechanism of a carburetor according to a first embodiment of the present invention will be described with reference to FIGS. Note that this embodiment is applied to the same carburetor as described in the above-mentioned conventional example, and only the structure different from that in the above-mentioned conventional example is illustrated, and the same reference numerals are given to the same members for explanation. Is omitted.

In this embodiment, the insertion hole 11 of the choke shaft 5A of the choke valve 5 formed in the carburetor body B forms a part of the insertion hole 11 in the middle of the primary side Venturi negative pressure passage 6A. The negative pressure introduced from the primary-side venturi negative pressure passage 6A to the combined negative pressure passage 7 can be adjusted according to the rotational position of 5A.

That is, as shown in FIG. 3, the choke shaft 5A is provided with a notch 12 having an appropriate length in the axial direction at a portion where the primary side venturi negative pressure passage 6A faces the insertion hole 11. The choke shaft 5A has a semicircular cross section as shown in FIG. Further, the upstream side portion 6A1 with respect to the insertion hole 11 of the primary side venturi negative pressure passage 6A is substantially perpendicular to the downstream side portion 6A2, and when the choke valve 5 is fully opened, the upstream side portion 6A1 is shown as shown in FIG. And the downstream side portion 6A2 are connected to each other by the notch 12, the primary side Venturi negative pressure passage 6A is in a fully opened state, while the choke valve 5 is in a choked state, the upstream side portion 6A1 and the downstream side portion 6A1 are shown in FIG. The side portion 6A2 and the side portion 6A2 are completely closed by the choke shaft 5A so that the primary side venturi negative pressure passage 6A is fully closed.

In this embodiment, the combined negative pressure from the primary-side venturi negative pressure passage 6A and the secondary-side venturi negative pressure passage 6B does not directly go through the solenoid valve 9 of the above-mentioned conventional example, but directly passes through the secondary valve diaphragm. It is led to 8.

In this embodiment, when the choke valve 5 is fully opened, the primary-side venturi negative pressure passage 6 A is in the fully-opened state, and the primary-side venturi negative pressure is directly combined with the secondary-side venturi negative pressure to form the secondary valve. Guided by the diaphragm 8. Next, when the choke valve 5 is closed, the primary side Venturi negative pressure passage 6A is gradually throttled by the choke shaft 5A accordingly, so that the combined negative pressure becomes small and the secondary side throttle valve 4B is opened. When the choke valve 5 is in the choked state, the primary venturi negative pressure passage 6A is completely shut off, and the opening degree of the secondary throttle valve 4B is further reduced.

Therefore, even if the choke valve 5 is throttled, the amount of air from the secondary side intake passage 3B does not increase, so the mixture ratio does not become thin and can be adjusted to an optimum value.

Next, a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. Unlike the first embodiment, this embodiment does not control the opening degree of the secondary side throttle valve 4B by opening and closing the primary side venturi negative pressure passage 6A, but the same solenoid valve as in the conventional example. The valve 9 is used to control the combined negative pressure from the primary side Venturi negative pressure passage 6A and the secondary side Venturi negative pressure passage 6B. However, in the present embodiment, the operation of the solenoid valve 9 is not performed by turning on / off the water temperature switch 10 as in the conventional example.

As shown in FIG. 4, a lever 13 is inserted through one end of the choke shaft 5 A of the choke valve 5 via its sleeve 13 a, and the lever 13 is attached to the choke shaft 5 A via a spring 14. It is mounted so that it can follow and rotate. A nut 15 is screwed onto the end of the choke shaft 5A, and the axial position of the lever 13 is restricted by the nut 15. A micro switch 16 for operating the solenoid valve 9 is arranged near the lever 13 as shown in FIG.

The micro switch 16 is turned on by the lever 13 when the choke valve 5 is in the fully open position shown by the chain line in FIG. 5, and the solenoid valve 9 is opened to open the primary side venturi negative pressure passage 6A and the secondary side venturi negative pressure. The combined negative pressure from the passage 6B is guided to the secondary valve diaphragm 8. On the other hand, as shown by the solid line in FIG. 5, when the choke valve 5 is in the choked state and the levers 13 are located apart from each other, the solenoid valve 9 is closed and the primary side venturi negative pressure passage 6A and the secondary side. The synthetic negative pressure from the side venturi negative pressure passage 6B is cut off to reduce the opening degree of the secondary side throttle valve 4B.

That is, in this embodiment, as in the first embodiment, even if the choke valve 5 is throttled, the amount of air from the secondary side intake passage 3B does not increase, so the mixing ratio does not become thin. , Can be adjusted to the optimum value.

It should be noted that the solenoid valve 9 is connected to a pressure leakage pipe line 17 to the outside air as shown in FIG. 6 so that the solenoid valve 9 is combined when the choke valve 5 is in the choked state and the lever 13 is located away from the solenoid valve 9. The negative pressure may be configured to leak to the outside through the pressure leak line 17.

[0017]

[Effect of device]

 The present invention has an advantage that it is possible to surely prevent the mixture ratio from being diluted in the choked state based on the change in the opening degree of the choke valve and improve the drivability.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of a secondary side throttle valve opening control mechanism of a carburetor according to a first embodiment of the present invention.

FIG. 2 is a view similar to FIG. 1 showing different operating states.

FIG. 3 is a view showing a cutout state of the choke shaft of FIG.

FIG. 4 is a view showing a state in which a lever of a secondary side throttle valve opening control mechanism of a carburetor according to a second embodiment of the present invention is attached to a choke shaft.

5 is a view showing the arrangement of the lever of FIG. 4 with respect to the micro switch together with its related parts.

6 is a diagram of a main part showing another example of FIG.

FIG. 7 is a view showing a secondary side throttle valve opening control mechanism of a conventional carburetor.

[Explanation of symbols]

 2A Primary side venturi 2B Secondary side venturi 4B Secondary side throttle valve 5 Choke valve 6A Primary side venturi negative pressure passage 6B Secondary side venturi negative pressure passage 8 Secondary valve diaphragm (actuator)

Claims (1)

[Scope of utility model registration request] 1. A secondary of a carburetor, comprising an actuator having an operating pressure of a combined negative pressure of a venturi negative pressure of a primary side and a secondary side, and controlling an opening of a secondary side throttle valve by the operation of the actuator. A side throttle valve opening control mechanism, wherein the operating pressure of the actuator is based on a change in the opening degree of the choke valve, and the opening degree of the secondary side throttle valve is smaller when the choke valve is in the choke state than in the fully open state. A secondary side throttle valve opening control mechanism for a carburetor, which is characterized in that