JPH06336955A - Fuel quantity adjusting device for engine - Google Patents

Abstract

PURPOSE:To carry out the opening adjustment of a needle valve within a range regulated by a quantity adjusting hole by providing the bottom wall of a plug with the quantity adjusting hole opened being decentered from the center point, providing the base end face of a male screw part with a quantity adjustment operating protrusion in the state of being inserted through the quantity adjusting hole, and adjusting the male screw by screwing motion only in a range of the quantity adjustment operating protrusion being movable in the quantity adjusting hole. CONSTITUTION:A cap like plug 9 is unremovably fitted in and fixed to the base end opening part 4 of a valve accommodating hole. A quantity adjusting hole 12 decentered from the center point 11 is opened in the bottom wall 10 of the plug 9, and the base end face 13 of a male screw part 8 is protrusively provided with a quantity adjustment operating protrusion 15 decentered from the center point 14. This quantity adjustment operating protrusion 15 is inserted through the quantity adjusting hole 12 so as to enable the screwing adjustment of the male screw part 8 only in a range where the quantity adjustment operating protrusion 15 can move in the quantity adjusting hole 12. An engine user can thereby adjust the male screw part 8 by screwing motion only in the range of the quantity adjustment operating protrusion 15 being movable in the quantity adjusting hole 12. The opening of a needle valve 5 can be thereby adjusted only in the range regulated by the quantity adjusting hole 12. The fuel supply quantity can be thus made appropriate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine fuel metering device, and more particularly to a device for preventing the opening of a needle valve from being significantly changed by a user of the engine.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional technology of an engine fuel metering device. Like the present invention, it has the following basic structure. That is, the fuel supply port 102 communicating with the intake passage 101 is provided at a position on the tip side of the valve accommodation hole 103, and the needle valve 105 inserted from the proximal end opening 104 thereof is accommodated in the valve accommodation hole 103. A valve head 106 at the tip of 105 is inserted into the fuel supply port 102, a male thread portion 108 is formed at the base end portion of the needle valve 105, and this male thread portion 108 is formed on the inner peripheral surface of the valve accommodating hole 103. It is configured to be screw-fitted to 107, and the opening degree of the needle valve 105 is adjusted by the screwing of the male screw portion 108.

In this prior art, as long as the male screw portion 108 can be screwed by the female screw portion 107, the needle valve 105
The degree of opening can be adjusted over a wide range.

[0004]

The above-mentioned conventional techniques have the following problems. Since the opening of the needle valve 105 can be adjusted over a wide range, the engine manufacturer ships the engine by adjusting the opening of the needle valve 105 optimally from the viewpoint of output performance and exhaust gas regulation. However, the engine user may significantly change the opening degree of the needle valve 105 to an unsuitable range. In this case, the needle valve 10
If the opening degree of 5 is too small, the amount of fuel supplied to the intake passage 101 will be insufficient, the output performance will be significantly reduced, and a stable operating state cannot be guaranteed. On the other hand, the needle valve 10
If the opening degree of 5 is too large, the amount of fuel supplied to the intake passage 101 becomes excessive, which may deviate from the allowable range such as exhaust gas regulations.

In order to solve the above problem, as shown in FIG. 4, the male screw portion 108 is shortened, and the engine manufacturer adjusts the opening degree of the needle valve 105 to the optimum value, and then the base end opening of the valve accommodating hole 103. It is conceivable that the steel ball 117 is press-fitted into the portion 104 and the needle valve 105 is unadjustable before shipment. However, in this case, the engine user can open the needle valve 105 depending on the engine usage condition. There is a new problem that it becomes impossible to finely adjust.

An object of the present invention is to provide an engine fuel metering device capable of preventing the opening degree of a needle valve from being significantly changed by a user of the engine.

[0007]

In the present invention, as shown in FIG.
As illustrated in the enlarged view of FIG. 2 or the enlarged view of FIG. 2, the fuel supply port 2 communicating with the intake passage 1 is provided at a position on the front end side of the valve housing hole 3, and the base end opening 4 of the valve housing hole 3 The needle valve 5 inserted from the above is accommodated, the valve head 6 at the tip of the needle valve 5 is inserted into the fuel supply port 2, and the male screw portion 8 is formed at the base end portion of the needle valve 5, and the male screw portion 8 is inserted. In the fuel metering device for the engine, which is configured to be screwed into the female screw portion 7 formed on the inner peripheral surface of the valve housing hole 3 and to adjust the opening degree of the needle valve 5 by the screwing of the male screw portion 8, It is characterized by doing like.

That is, an enlarged view of FIG. 1 (A) or FIG.
As illustrated in the enlarged view of FIG. 3, a cap-shaped plug 9 is non-removably fitted and fixed to the base end opening 4 of the valve accommodating hole 3, and the bottom wall 10 of the plug 9 is eccentric from the center point 11 thereof. A metering hole 12 is opened, a metering operation projection 15 eccentric from the center point 14 is provided on the base end surface 13 of the male screw portion 8, and this metering operation projection 15 is inserted into the metering hole 12, and the metering hole 12 is inserted. It is characterized in that the male screw portion 8 can be screwed and adjusted only within a range in which the operation protrusion 15 can move in the metering hole 12.

[0009]

As illustrated in the enlarged view of FIG. 1 (A) or the enlarged view of FIG. 2, the engine manufacturer, from the viewpoint of output performance, exhaust gas regulation, and the like, operates the needle valve 5 by screwing the male screw portion 8. Is adjusted to an optimum opening degree, and the base end opening 4 of the valve accommodating hole 3 is adjusted.
The engine is shipped after the plug 9 is fitted and fixed in the. In this way, the engine user can use the metering operation projection 1
The male screw portion 8 can be screwed and adjusted only within a range in which the meter 5 can move in the metering hole 12, and the opening degree of the needle valve 5 can be adjusted only within the range regulated by the metering hole 12.

That is, by moving the adjusting operation projection 15, the male screw portion 8 can be screwed to adjust the opening degree of the needle valve 5, but the adjusting operation projection 15 is the edge of the adjusting hole 12. When contacting the portion 16 (see FIG. 1 (C)), the male screw portion 8 cannot be screwed further, so that the opening degree of the needle valve 5 can be adjusted only within the range regulated by the metering hole 12. Can not be done.

[0011]

From the viewpoint of output performance and exhaust gas regulation, the engine manufacturer adjusts the needle valve to an optimum opening degree by screwing the male thread portion and inserts the plug into the base end opening portion of the valve accommodating hole. When the engine is shipped after fixing, the engine user can screw adjust the male screw only within the range in which the metering operation protrusion can move in the metering hole, and within the range regulated by this metering hole. However, since the opening degree of the needle valve can only be adjusted, there is no risk that the operating state will become unstable due to excess or deficiency of the amount of fuel supplied to the intake passage, or that the allowable range for exhaust gas regulations, etc. will be exceeded.

Since the opening degree of the needle valve can be finely adjusted within the range regulated by the metering hole, the engine user can make the fine adjustment according to the usage situation of the engine.

[0013]

Embodiments of the present invention will be described with reference to the drawings.
1A and 1B are views for explaining an engine fuel metering device according to a first embodiment of the present invention. FIG. 1A is a cross-sectional plan view of a carburetor, FIG. 1B is a vertical sectional side view of a carburetor, and FIG.
(C) is a C direction arrow view of FIG. 1 (A).

The carburetor 19 shown in FIG. 1 has a float chamber 21 below the mixing body 20. An intake passage 1 provided with a venturi 22 is provided in the mixing body 20, and air from an air cleaner (not shown) flows into the intake passage 1 in the direction of arrow 24. Venturi 2
A choke valve 25 is provided on the upper side of 2, and a throttle valve 26 is provided on the lower side of the venturi 22.

The structure of the main system is as follows. Figure 1
As shown in (B), a main nozzle mounting boss 27 is vertically provided from a position of the venturi 22 of the mixing body 20, and a main nozzle 28 is fitted therein. The lower end opening 29 of the main nozzle 28 has a main fuel supply port 30.
Is connected to the float chamber 21 via the main nozzle 28
The upper end opening 31 of the is communicated with the venturi 22.
Further, the plurality of air introduction holes 32 provided in the middle of the main nozzle 28 are communicated with the surrounding main air bleed chamber 33, and the main air bleed chamber 33 is communicated with the main air bleed 34 shown in FIG. ing.

When the throttle valve 26 has a relatively large opening degree at high and medium speeds, the negative pressure generated in the venturi 22 causes the fuel in the float chamber 21 to flow into the main fuel supply port 30.
The air is sucked up by the main nozzle 28 through the above, is mixed with the air sucked from the main air bleed 34, and is jetted as a mixture from the upper end opening 31 of the main nozzle 28.

The structure of the slow system is as follows. Figure 1
As shown in (B), the main nozzle mounting boss 27
A fuel supply passage 35 is provided in parallel with the main nozzle 28. As shown in FIG. 1 (A), a pilot air bleed 37 is provided in a peripheral wall 36 of the intake passage 1, a fuel supply passage 35 is communicated with the pilot air bleed 37, and a slow port is communicated with the intake passage 1 near the end. 38 and idle port 3
And 9 are provided in order.

At the time of idling when the opening degree of the throttle valve 26 is almost fully closed, the negative pressure generated in the gap 40 between the throttle valve 26 and the peripheral wall 36 of the intake passage 1 causes the fuel in the float chamber 21 to be the main fuel. Supply port 30
It is sucked up by the pilot air bleed 37 through the fuel supply passage 35 in order, is mixed with the air flowing therein, and is jetted as a mixture from the idle port 39.
Further, at the time of low speed rotation in which the opening degree of the throttle valve 26 becomes slightly large, the air-fuel mixture is jetted from both the idle port 39 and the slow port 38 due to the negative pressure generated in the gap 40.

The amount of the air-fuel mixture ejected from the idle port 39 can be adjusted by the fuel adjusting device 41. The structure of the fuel metering device 41 is as follows. That is, the idle port 39 is provided at a position on the tip end side of the valve housing hole 3, and the needle valve 5 inserted from the base end opening 4 is housed in the valve housing hole 3. The valve head 6 at the tip of the needle valve 5 is inserted into the fuel supply port 2, the male thread portion 8 is formed at the base end portion of the needle valve 5, and the male thread portion 8 is formed on the inner peripheral surface of the valve housing hole 3. The female thread portion 7 is screw-fitted, and the opening of the needle valve 5 is adjusted by screwing the male thread portion 8.

In this embodiment, in order to prevent the opening degree of the needle valve 5 from being significantly changed by the engine user, the following structure is adopted.
That is, the cap-shaped plug 9 is fitted in the base end opening 4 of the valve accommodating hole 3. The plug 9 is fitted and fixed to the base end opening 4 by press fitting in a substantially non-removable manner. The bottom wall 10 of the plug 9 is provided with a metering hole 12 which is eccentric from the center point 11 of the bottom wall 10, and the base end surface 13 of the male screw portion 8 is formed.
A metering operation projection 15 eccentric from the center point 14 is provided at the center. The metering operation projection 15 is used as the metering hole 1
It is configured so that the male screw portion 8 can be screw-adjusted only within a range in which the metering operation projection 15 can be moved in the metering hole 12.

The engine manufacturer adjusts the opening degree of the needle valve 5 to the optimum opening degree by screwing the male threaded portion 8, fits and fixes the plug in the base end opening portion 4 of the valve accommodating hole 3, and then ships the engine. . In this way, the engine user can screw adjust the male screw portion 8 only within the range in which the metering operation projection 15 can move in the metering hole 12, and within the range regulated by the metering hole 12. Only the opening of the needle valve 5 can be adjusted.

FIG. 2 is a vertical sectional side view of a carburetor equipped with an engine fuel metering device according to a second embodiment of the present invention. In the second embodiment, the fuel metering device 41 is provided at the inner bottom of the float chamber 21, and the needle valve 5 controls the amount of fuel passing through the main fuel supply port 30.

[Brief description of drawings]

1A and 1B are views for explaining a fuel metering device for an engine according to a first embodiment of the present invention, FIG. 1A is a cross-sectional plan view of a carburetor, and FIG. 1B is a vertical side view of a carburetor. 1
(C) is a C direction arrow view of FIG. 1 (A).

FIG. 2 is a vertical cross-sectional side view of a carburetor equipped with an engine fuel metering device according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional plan view of a carburetor including a fuel metering device for an engine according to the related art.

FIG. 4 is an enlarged view of a main part of a preceding trial production example.

[Explanation of symbols]

1 ... Intake passage, 2 ... Fuel supply port, 3 ... Valve accommodation hole, 4 ... Base end opening, 5 ... Needle valve, 6 ... Valve head, 7 ... Female screw hole,
8 ... Male part, 9 ... Plug, 10 ... 9 bottom wall, 11 ... 9
Center point, 12 ... metering hole, 13 ... 8 base end surface, 14 ... 1
Center point of 3, 15 ... Protrusion operation protrusion.

Claims (1)

[Claims] 1. A fuel supply port (2) communicating with the intake passage (1)
Is provided at the position on the tip side of the valve accommodating hole (3), and the valve accommodating hole is
Needle valve (5) inserted into its (3) through its proximal opening (4)
The needle valve (5), the valve head (6) at the tip of the needle valve (5) is inserted into the fuel supply port (2), and a male screw part (8) is formed at the base end of the needle valve (5). Thread the male thread (8) into the valve hole (3)
A fuel metering device for an engine, which is configured to be screw-fitted into a female screw portion (7) formed on the inner peripheral surface of the engine, and the opening degree of the needle valve (5) is adjusted by screwing the male screw portion (8). In the above, a cap-shaped plug (9) is non-removably fitted and fixed to the base end opening (4) of the valve accommodating hole (3), and the center point (11) ) Eccentric from the metering hole (1
2) and open the center point on the base end face (13) of the male thread (8).
A metering operation protrusion (15) which is eccentric from the (14) is projected, and the metering operation protrusion (15) is inserted into the metering hole (12). A fuel adjusting device for an engine, characterized in that the male screw portion (8) can be screw-adjusted only within a range in which it can move.