JPH0530438U - Air-fuel ratio controller for engine - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to an engine air-fuel ratio control device, which can bring the air-fuel ratio close to 1, and which is simple and does not require manual operation. With the goal. [Composition] A shaft of a butterfly valve mounted on a shaft at a position deviated from the center is pivotally supported by a minimum diameter part of a venturi part for mixing air and fuel gas from which fuel gas is ejected,
A biasing member was installed in the closing direction of the butterfly valve.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an engine air-fuel ratio control device for improving the air-fuel ratio of an engine in which fuel gas and air are mixed and burned in a cylinder.

[0002]

[Prior Art]

 FIG. 4 shows a venturi portion of a conventional engine that mixes fuel gas and air and burns them in a cylinder, and this will be described below.

Reference numeral 1 denotes a suction pipe for sucking air into a cylinder. A part of the suction pipe is provided with a venturi portion 2 whose inner diameter is gradually reduced and then gradually enlarged, and a minimum diameter portion 2a of the venturi portion 2 is provided. An ejection hole 3 for ejecting fuel gas is formed, and in the figure, an arrow a indicates a direction of an air flow that is sucked in, and a b indicates a direction of a fuel gas that is sucked by this air flow.

When air passes through the venturi section 2 due to the intake force generated by the rotation of the engine, the shape of the venturi section 2 increases the velocity of the air passing through the venturi section 2, resulting in a negative pressure in this section, which results in a negative pressure. The fuel gas is ejected from the ejection holes 3 by the suction force of the pressure, and the air and the fuel gas are mixed.

As a device for supplying fuel into the inhaled air of an engine that mixes and burns gas and air as described above, there is a gas engine fuel supply device described in Japanese Utility Model Laid-Open No. 60-92742. is there.

This fuel supply device for a gas engine relates to a configuration in which a bypass passage is provided and an air-fuel ratio adjusting valve is provided in the bypass passage when mixing fuel and air by a carburetor. Since this is different from the one in which air and air are mixed, consideration on this is omitted.

[0007]

[Problems to be solved by the device]

 In the device for mixing fuel gas and air in the venturi as described above, when the engine speed and load are small, the negative pressure generated in the venturi section 2 is small, so the ratio of fuel to air is low. As the number of revolutions or the load increases, the negative pressure increases greatly, and the fuel becomes rich.

That is, the increase in the fuel gas increases as the amount of air taken in increases, and the gas flow rate is plotted on the vertical axis and the air flow rate associated with load, etc. is plotted on the horizontal axis. As shown in FIG. 5, the theoretical air-fuel ratio of 1 is represented by a straight line, but in this type of Venturi device, the theoretical air-fuel ratio of the dotted line in the same figure is obtained.

In order to purify exhaust gas by using a three-way catalyst, it is necessary to maintain the theoretical air-fuel ratio of 1, which is the precondition, but the above change in air-fuel ratio is caused by, for example, passenger car gasoline engine. Even if the electronically controlled air-fuel ratio control device used is used, the air-fuel ratio control that maintains the air-fuel ratio of 1 from load 0 to full load becomes impossible.

The present invention solves the above-mentioned problems in an engine using a conventional Venturi device, and brings the air-fuel ratio close to 1 with a simple mechanism to provide an air-fuel ratio control device useful for high engine output and environmental purification. The purpose is to provide.

[0011]

[Means for Solving the Problems]

 The present invention is an air-fuel ratio control device for an engine, in which an injection hole for injecting fuel gas is provided in the minimum diameter portion of the venturi portion of an intake pipe provided with the venturi portion. A butterfly valve having a shaft at a position deviated from the center is pivotally supported, and a biasing member is installed on the shaft in a direction in which the butterfly valve closes the venturi portion.

[0012]

[Action]

 In the air-fuel ratio control device for an engine of the present invention, when the amount of air passing through the venturi portion is small, the ram pressure on the butterfly valve is small, so that the butterfly valve is closed by the biasing force of the biasing member. As it rotates, the venturi portion is throttled, the inflow speed of the intake air increases, and a large amount of fuel gas is sucked out due to the negative pressure.

However, as the amount of air passing through the venturi increases due to an increase in the number of revolutions of the engine, etc., the butterfly valve is pivotally supported at a position deviated from the center of the butterfly valve. An imbalance of the ram pressure due to the flow velocity occurs, which causes the butterfly valve to be pressed in the direction of rotation, tilt against the biasing member, and open the venturi portion, so the amount of fuel gas sucked from the ejection hole is increased. Is to be adjusted.

[0014]

【Example】

 Next, an example of implementation of the present invention will be described with reference to FIGS. In FIGS. 1 and 2, 1 is an intake pipe, 2 is a venturi portion, 2a is a minimum diameter portion thereof, 3 is an injection hole provided in the minimum diameter portion 2a for ejecting fuel gas, and 4 is an intake air An air cleaner, 5 is a throttle valve that controls the engine speed by limiting the amount of air-fuel mixture that is taken into the engine, and 6 is a manifold that distributes the taken air-fuel mixture to each cylinder. The parts are not different from conventional ones.

Inside the venturi portion 2, a butterfly valve 7 having an inner diameter close to that of the butterfly valve 7 is fixed to a shaft 8 at a position deviated from its center, and the shaft 8 is rotatably supported by the smallest diameter portion 2a. Has been done.

A torsion spring 9 is mounted on the shaft 8 in a direction in which the butterfly valve 7 closes the venturi portion 2. When the butterfly valve 7 receives an air flow in the direction of arrow a in FIG. Since the shaft 8 of the butterfly valve 7 is deviated from its center, the force due to the air flow becomes unbalanced in the upward and downward directions of the shaft 8, which the butterfly valve 7 resists against the bias of the torsion spring 9. You will receive the force to open it.

Since the ram pressure for opening the butterfly valve 7 is small when the air flow is slow, the butterfly valve 7 is rotated by the biasing force of the torsion spring 9 in the direction of closing the venturi portion 2. To do.

On the other hand, when the air flow becomes faster, the unbalanced ram pressure generated in the butterfly valve 7 as described above resists the biasing force of the torsion spring 9 and causes an angle corresponding to the speed of the air flow. It will only open. .

Therefore, when the flow rate of air is small, the venturi portion 2 is throttled, the velocity of the air flow passing through the minimum diameter portion 2a is increased, the negative pressure is increased, and the vent hole 3 is discharged. The amount of fuel gas inhaled increases.

On the other hand, when the flow rate of the air increases, the venturi section 2 is opened according to the speed of the air flow, so that the negative pressure does not increase so much and the intake of the fuel gas is reduced. The quantity is adjusted.

Similar to FIG. 5, FIG. 3 shows the mixing ratio of fuel gas and air with the gas flow rate on the vertical axis and the air flow rate on the horizontal axis. A in FIG. 3 indicates the dotted line in FIG. The air-fuel ratio in the same conventional Venturi device as shown in (4), C is a line with an air-fuel ratio of 1, and B is the air-fuel ratio of one embodiment of the present invention. It is possible to bring the air-fuel ratio up to the load close to 1.

In carrying out the present invention, the area and shape of the butterfly valve 7 are the ratio and shape of the butterfly valve 7 to the minimum diameter portion 2a of the venturi portion 2, the spring constant of the torsion spring 9, the passage area of the fuel gas, and the fuel. It is necessary to match the actual engine such as gas pressure.

[0023]

As described above, according to the present invention, since the air-fuel ratio can be set to a state close to the theoretical air-fuel ratio of 1 from 0 load to full load of the engine, not only the output of the engine can be improved. When purifying engine exhaust gas using a three-way catalyst, the prerequisites for using a three-way catalyst can be almost satisfied.

Therefore, it is possible to reduce environmental pollution due to engine exhaust gas, contribute to environmental purification, have a simple configuration, and do not require manual operation for the air-fuel ratio. is there.

[Brief description of drawings]

FIG. 1 is a schematic sectional side view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a mixture ratio diagram of fuel gas and air according to the present invention.

FIG. 4 is a cross-sectional view of a conventional device.

FIG. 5 is a conventional mixing ratio diagram of fuel gas and air.

[Explanation of symbols]

 2 Venturi part 2a Minimum diameter part 3 Jet hole 7 Butterfly valve 8 Shaft 9 Torsion spring

Claims (1)

[Scope of utility model registration request] 1. An air-fuel ratio control device for an engine, wherein an injection hole for injecting fuel gas is provided in a minimum diameter portion of the venturi portion of an intake pipe provided with the venturi portion. A butterfly valve having a shaft provided at a position deviated from the center, and an urging member is installed on the shaft in such a direction that the butterfly valve closes the venturi portion. Fuel ratio control device.