JPH06137215A - Gaseous fuel supplying device for engine - Google Patents

Abstract

PURPOSE:To reduce the harmful components in the exhaust, and to enhance the operating performance of an engine by distributedly supplying gaseous fuel to respective engine cylinders accurately and by a proper quantity. CONSTITUTION:The flow rate of gaseous fuel passing through a fuel passage is controlled by a fuel valve 12 that has been interlocked with an air valve 5 which is opened or closed so as to maintain the pressure in the space between a throttle valve 4 in an intake passage 1 and the air valve 5 at a given negative pressure. Further, the gaseous fuel is controlled by a constant-pressure control valve 31 in response to the intake air pressure upstream of each intake manifold 3, and is supplied to each of the cylinders of an engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a gaseous fuel such as LPG or CNG at a flow rate corresponding to an intake air amount and distributing the fuel to each cylinder of an engine.

[0002]

2. Description of the Related Art High pressure gas fuel such as LPG and CNG is decompressed to the atmospheric pressure and sent to an intake passage by a negative pressure generated by intake air, mixed with air and supplied to an engine in a high output range. Instead of a mixer that uses a fixed venturi that gives a large intake resistance, an air valve is installed upstream of the throttle valve to create a constant negative pressure chamber between them and a constant negative pressure according to changes in the intake air amount. By opening and closing the fuel valve installed in the fuel passage in conjunction with the air valve that operates to maintain the pressure in the pressure chamber constant, the gaseous fuel is metered to the flow rate according to the intake air amount and sent to the intake passage. It has been proposed (Japanese Patent Publication No. 47-36536).

That is, when the throttle valve opening is small and the intake air amount is small, the negative pressure on the upstream side is low, so the air valve is set to a small opening, and the fuel valve interlocked with this is also a small opening and the gas fuel flow rate is small. When the throttle valve opening is increased and the intake air amount is increased to increase the negative pressure on the upstream side of the throttle valve, the opening of the air valve increases and the negative pressure decreases and the opening of the fuel valve increases. Is increased and the flow rate of gaseous fuel is increased to make the air-fuel mixture have a substantially constant concentration. Since the air valve functions like a variable venturi, the output can be improved as compared with a fixed venturi.

However, since the gas fuel is supplied to the constant negative pressure chamber in the system proposed in the above publication,
Similar to the conventional mixer that is supplied from the fixed venturi part, it is sent to the engine without being uniformly mixed with intake air in the high load range, and the air-fuel ratio of each cylinder becomes non-uniform, increasing harmful components in the exhaust gas. Inevitable.

[0005]

The problem to be solved by the present invention is to install an air valve on the upstream side of the throttle valve in the intake passage and a fuel valve in the fuel passage for feeding gaseous fuel into the intake passage. The fuel valve is opened and closed in conjunction with the air valve that opens and closes so that the intake air pressure in the portion between the valve and the air valve is constant, so that the gaseous fuel at a flow rate according to the intake air amount is supplied. According to the above device, the fuel distribution to each cylinder of the engine in the high load range is not good.

[0006]

In order to solve the above-mentioned problems, the present invention divides and connects a fuel passage for each intake manifold corresponding to each engine cylinder in the intake passage, and connects a throttle valve and an air valve. A constant pressure control valve that controls the gaseous fuel to a pressure corresponding to the intake air pressure on the upstream side or the air valve will be provided in each branch fuel passage, which will improve the fuel distribution to each engine cylinder The purpose of reducing the harmful components of was achieved.

[0007]

The air valve and the fuel valve are interlocked with each other to open and close according to the change in the intake air amount controlled by the throttle valve, and the gaseous fuel is metered at a flow rate corresponding to the intake air amount. The metered gaseous fuel is distributed to each cylinder of the engine by the branch fuel passage, and at that time, a constant pressure control valve equals or has a constant difference with the intake air pressure at the portion between the throttle valve and the air valve or the upstream portion of the air valve. By controlling the pressure, a predetermined amount of gaseous fuel is accurately supplied to each cylinder.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. A throttle valve 4 and an air valve 5 located upstream of the throttle valve 4 are installed in an intake pipe line 2 of an intake line 1 from an air cleaner (not shown) to an engine. A fuel valve 12 is installed in a fuel passage 11 extending from a pressure regulator such as a vaporizer (not shown).
The operating rods 16 and 17 connected to the levers 7 and 14 fixed to the valve shafts 6 and 13 by a length adjusting mechanism 15 including a screw and a nut are rotatably attached.
As a result, the air valve 5 and the fuel valve 12 are opened and closed at an arbitrary rotation angle ratio.

An end of the operating rod 16 on the side opposite to the adjusting mechanism 15 is rotatably connected to an arm 20 projecting from a diaphragm 19 of a negative pressure actuator 18. The negative pressure chamber 21 of the negative pressure actuator 18 communicates with a portion of the intake pipe line 2 between the throttle valve 4 and the air valve 5, that is, the constant negative pressure chamber 8 and the negative pressure passage 22, and is separated by the diaphragm 19. The enclosed air chamber 23 is in communication with the upstream side of the air valve 5 of the intake pipe line 2 by the air passage 24, and the diaphragm 19 is pushed toward the air chamber 23 by the spring 25 inserted in the negative pressure chamber 21. There is.

When the opening degree of the throttle valve 4 is small and the intake air amount of the engine is small, the negative pressure of the constant negative pressure chamber 8 is low, so the negative pressure actuator 18 pushes the operating rods 16 and 17 to the right in the drawing. 5, the fuel valve 12 is set to a small opening, and the fuel valve 1
2 supplies the engine with a gaseous fuel commensurate with the flow rate of intake air. Since the negative pressure in the constant negative pressure chamber 8 increases as the opening degree of the throttle valve 4 increases and the intake air amount increases, the negative pressure actuator 18 pulls the operating rods 16 and 17 to the left in the drawing to pull the air valve 5 and the fuel. The opening degree of the valve 12 is increased. As a result, the negative pressure in the constant negative pressure chamber 8 becomes low again, but the air valve 5 becomes the throttle valve 4
The fuel valve 12 which maintains the opening degree for passing the intake air amount controlled by the above, supplies the gaseous fuel corresponding to the intake air flow rate to the engine.

A fuel passage 11 is provided in each intake manifold 2 corresponding to each engine cylinder in the intake passage 1.
A branched fuel passage 26 that is branched downstream is connected.

The intake manifold 2 of the branch fuel passage 26
The effective area of the nozzle port 27 formed at the opening end of the opening is controlled by the constant pressure control valve 31. That is, the constant pressure control valve 31 includes a diaphragm 33 to which a needle-shaped valve body 32 is fixed,
The intake air chamber 34 is separated from the branch fuel passage 26 by the diaphragm 33, and the spring 35 acting on the diaphragm 33 in a direction to reduce the effective area of the nozzle port 26 is provided. The intake air chamber 34 is a constant negative pressure chamber. 8 and 36
Are in communication with each other.

The negative pressure in the constant negative pressure chamber 8 is higher when the opening degree of the throttle valve 4 is larger than when the opening degree is small, and maintains a constant negative pressure according to the intake air amount. Therefore, when the intake air amount is small, a low negative pressure is introduced into the intake air chamber 34 to reduce the effective area of the nozzle port 27, and when the intake air amount is large, the effective area of the nozzle port 27 is increased. The pressure of the gaseous fuel is controlled to the same level as the pressure of the constant negative pressure chamber 8. That is, the gas fuel whose flow rate is controlled by the fuel valve 12 so as to correspond to the intake air amount is further pressure-controlled by the constant pressure control valve 31 to be adjusted to an appropriate amount and sent to the intake manifold 3, whereby the gas fuel is supplied to each cylinder of the engine. The gaseous fuel commensurate with the amount of intake air for each cylinder will be accurately supplied.

When the throttle valve 4 is suddenly opened, the constant negative pressure chamber 8 temporarily has a high negative pressure, which is the constant pressure control valve 3
Since the gas fuel downstream of the fuel valve 12 is immediately sent out by opening 1 widely, the gas fuel supply delay due to the operation delay of the air valve 5 and the fuel valve 12 is eliminated.

The conduction path 36 may be connected to the intake path 1 upstream of the air valve 5 as shown by a chain double-dashed line 37. In this case, the negative pressure generated on the upstream side of the air valve 5 depending on the opening degree of the air valve 5 which is determined by the intake air amount is the intake air chamber 3
4 and controls the gaseous fuel to a constant differential pressure with this negative pressure.

Further, in the present embodiment, an idle adjusting passage 42 having a manual adjusting valve 41 and a correction passage 44 having a solenoid valve 43 for feedback control are provided in the fuel passage 11 by bypassing the fuel valve 12 and idling. It has a configuration that stabilizes the engine and improves the accuracy of air-fuel ratio control.

[0017]

According to the present invention, the gaseous fuel measured at a flow rate corresponding to the intake air amount is distributed and sent to each intake manifold, so that the fuel distribution to each cylinder of the engine is uniform even in a high load region. Not only can the harmful components in the exhaust gas be reduced by controlling the flow rate of the gaseous fuel to the intake manifold, it also controls the flow rate of the gaseous fuel according to the intake air pressure. Further, a predetermined amount of gaseous fuel is accurately supplied to improve the engine operating performance.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

[Explanation of symbols]

1 intake passage, 3 intake manifold, 4 throttle valve,
5 air valves, 8 constant negative pressure chamber, 11 fuel passages, 1
2 fuel valves, 18 negative pressure actuators, 26 branch fuel passages, 31 constant pressure control valve,

Claims (2)

[Claims] 1. An intake valve is provided with an air valve upstream of a throttle valve in the intake passage, and a fuel valve is provided in a fuel passage for feeding gaseous fuel into the intake passage, and intake air pressure in a portion between the throttle valve and the air valve. In a gaseous fuel supply device for an engine that opens and closes the fuel valve in conjunction with the air valve that opens and closes so as to maintain a constant value; the fuel passage is branched for each intake manifold corresponding to each engine cylinder in the intake passage. And a constant pressure control valve for controlling the gaseous fuel to a pressure corresponding to the intake air pressure of the portion between the throttle valve and the air valve is installed in each of the branch fuel passages. Gas fuel supply device. 2. The device according to claim 1, wherein instead of the constant pressure control valve controlling the gaseous fuel to a pressure corresponding to the intake air pressure in the portion between the throttle valve and the air valve, the intake valve on the upstream side of the air valve is used. An engine gaseous fuel supply device configured to control gaseous fuel to a pressure according to air pressure.