NZ205825A - Gaseous fuel control for 1.c.engines;two passages with one controlled by valve - Google Patents

Description

205 8 Priority Date^): . ■ .'Q Complete Specification Filed: Class: Publication Data: ... A' 9.

P.O. Journal, No: ,t?S3 SEP 1983 No.: Date: NEW ZEALAND PATENTS ACT, 1953 COMPLETE SPECIFICATION "GASEOUS FUEL CONTROL DEVICE" ^We' REPCO LIMITED, a ccmpany organized and existing under the laws of the State of Victoria, Australia, of 630 St. Kilda Road, Melbourne, Victoria 3004, Australia, hereby declare the invention for which ixf we pray that a patent may be granted to xhe/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - 2 0 5 8 2 5 This invention relates to gaseous fuel supply systems for internal combustion engines and particularly such engines as used in automotive vehicles.

A difficulty with existing systems is that they do not provide satisfactory control of the air-fuel ratio throughout the entire operating range of the engines. At part throttle it is desirable for the purposes of economy and low exhaust emissions to provide a lean air-fuel mixture. At wide open throttle on the other hand, a relatively rich air-fuel mixture is required to achieve maximum power output.

Systems currently in use generally operate at a substantially fixed air-fuel ratio which may be a compromise between the requirements of part and full throttle. U.S. Patent 3,931,798 discloses a system in which the air-fuel ratio is automatically adjusted during operation of the engine, but that system is not entirely satisfactory in terms of construction and effectiveness in operation. The system requires use of a rather complex valve and does not adequately provide for the different characteristics of various engines with-which the system may be used. In particular, calibration of the system has a direct influence on the switching characteristics of the valve so that the total effectiveness of the system.may be disturbed as a result of such calibration.

It is an object of the present invention to provide a control device for a system of the foregoing kind which is of relatively simple construction and which permits convenient calibration whereby the system can have optimum effectiveness under various conditions of use.

According to the present invention, there is provided a gaseous fuel control device for use with internal combustion engines including, two flow passages each of which has an inlet connectable to a source of gaseous fuel and an outlet connectable to an engine intake manifold, and valve means operable to control flow of fuel through one of said passages and being connectable to a said engine so as to respond to the operating conditions thereof and control said flow accordingly.

The essential features of the invention, and further / 205825 optional features, are described in detail in the following passages of the specification which refer to the accompanying drawings. The drawings however, are merely illustrative of how the invention might be put into effect, so that the be essential or optional features) shown is not to be understood as limiting on the invention.

In the drawings: Figure 1 is an end view of a control device according to one embodiment of the invention; Figure 2 is a cross sectional view taken alone line II-II of figure 1; Figure 3 is a cross sectional view taken along line III-III of figure 1; Figure 4 .is a view similar to figure 2 but showing the valve in a partially closed condition; Figure 5 is a view similar to figure 2 but showing the valve in the fully closed condition;. / Figure 6 is a diagrammatic view of one possible system incorporating a control device according to the invention.

A control device according to the present invention is similar to that of U.S. Patent 3,9 31,798 in that it includes » a valve which is responsive to the operating conditions of an associated engine so as to control flow through a fuel supply passage. It differs from the previous proposal however, in that calibration of the flow characteristics through the device can be effected independently of the valve and it / includes two fuel flow passages, only one of which is controlled by the valve. attachment as a single unit into the fuel supply system of an existing engine. It may however, be formed of a plurality of separate parts which are independantly connectable into such a system, or it may be provided as original equipment in an engine fuel supply system.

According to the arrangement shown, the device 1 includes a hollow body 2 having an inlet port 3 and an outlet port &— specific form and arrangement of the features (whether they In the preferred form as hereinafter described, the device is of unitary construction so as to be capable of -SW- which communicate through the interior of the body 2 0 5 B 2 5 body interior is divided into two passages 5 and 6 to extend side by side in substantially parallel relationship (figure 3)'. For the purposes of the following description the passage 5 will be hereinafter called the primary passage and the passage 6 will be called the auxiliary passage.

A valve 7 is arranged to intrude into the auxiliary passage 6 so as to modify the flow characteristics of that passage 6, and the valve 7 is adapted to respond to the operating conditions of an associated engine so as to automatically modify the flow characteristics of the auxiliary passage 6. In the preferred construction shown, the valye 7 is responsive to fluid pressure and in particular is responsive to the negative pressure conditions existing within the engine inlet manifold 8 or some part of the engine system connected to that manifold 8 (figure 6).

The preferred valve 7 includes a member 9 which is slidable within a bore of the device body 2 extending transverse to the auxiliary passage 6. The member 9 may, as shown, comprise a body portion 10 and a piston 11 which are interconnected through a stem 12 'of relatively small cross section. In a non-operative position of the valve 7 (figure 2), the body portion 10 and piston 11 are located on respective opposite sides of the auxiliary passage 6 so as not to hinder fluid flow through that passage 6. The stem 12 extends across the passage 6, but it does not significantly affect fluid flow because of its small cross section. A spring 13 or other biasing means acts on the valve member 9 to normally urge the piston 11 into the non-operative position. Fluid pressure responsive means is arranged to effect movement of the valve member 9 against the action of the spring 13.

In the preferred construction shown, the piston 11 projects beyond one end of the bore in which it slides and a diaphragm 14 or similar flexible element is secured to the projecting portion 15 of that piston 11. The diaphragm 14 forms one wall of a chamber 16 which, in use, is connected through suitable conduit means 17 to the intake manifold 8 of an associated engine 18 (figure 6). The arrangement is such that the existence of negative pressure conditions in the intake manifold 8 causes the diaphragm 14 to flex so that —SW- the valve member 9 is pulled in a direction to move the body portion 10 into the auxiliary passage 6 so as to at least partially block that passage 6.

The device 1 preferably includes, as shown, separate calibration means 19 and 20 for each of the two passages 5 and 6. In each case, the calibration means 19 and 20 may include a member which can be projected into or withdrawn from the associated passage 5 or 6 respectively as required. According to the example shown, each calibration member is in the form of a screw 21 and 22 respectively which cooperatively engages within a threaded hole or bore of the device body 2. Rotation of the calibration screw 21 or 22 therefore alters its axial position and consequently the degree of intrusion into the associated passages 5 and 6 respectively. A coil compression spring 23 may be located between the head 24,25 of each calibration screw 21 and 22 and a surface of the device body 2 so as to resist rotation of the screw 21 or 22.

It is preferred, but not essential, that the auxiliary passage calibration screw 22 is located downstream of the vacuum responsive valve 7. Each screw 21 and 22 can be set to provide suitable flow characteristics through the associated passage 5 or 6 according to the operating characteristics and/or requirements of the associated engine 18. Since the auxiliary passage screw 22 is independant of the vacuum responsive valve 7 it can be adjusted without affecting the operating characteristics of that valve 7.

Figure 6 shows a typical installation incorporating the device 1 as described, in which the inlet port 3 of the device 1 is connected to the output side of a gas regulator 26 and the outlet port 4 is connected to a gas mixer 27 which may be a venturi-type device. The diaphragm chamber 16 of the valve 7 is connected through the conduit means 17 to the engine intake manifold 8.

Under part throttle conditions, a relatively high negative pressure exists within the engine inlet manifold 8. For example, at idling speed of the engine 18 the level of negative pressure could be such that the valve 7 is drawn into the fully operative position such that the auxiliary 6 is completely blocked against fluid flow (figure 5), . 205825 calibration screw 21 of the primary passage 5 may be set to provide the desired air-fuel ratio at the venturi 27 when the entire gas flow is through that primary passage 5.

As the throttle is opened further, the negative pressure level drops and the valve 7 opens accordingly. At the full throttle condition, the valve 7 may be fully opened (figure 2) and the calibration screw 22 of the auxiliary passage 6 is set to provide the desired air-fuel ratio under those circumstances. That is, the combined gas flow through the two passages 5 and 6 is such that the desired ratio is obtained. At intermediate throttle positions (e.g., .as shown in figure 4) the valve 7 regulates the flow through the auxiliary passage 6 so that the combined flow at the outlet port 4 of the device 1 is satisfactory.

It will be appreciated from the foregoing description that a device according to the invention has several advantages over prior devices. In particular, the mixture adjustment is independant of the switching characteristics of the valve. Each calibration screw can cover a large adjusting range to suit a wide variety of engine and mixer designs, and that adjustment can be made without affecting the operation of the pressure responsive valve. As manifold vacuum levels between engines are a common parameter, one calibration of the pressure responsive valve can be used to suit all engines if desired.

Various alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the spirit or ambit of the invention as defined by the appended claims.

Claims (10)

WHAT^WE CLAIM IS

1. A gaseous fuel control device for use with internal combustion engines including, two flow passages each of which has an inlet connectable to a source of gaseous fuel and an outlet connectable to an engine intake manifold, and valve means operable to control flow of fuel through one of said passages and being connectable to a said engine so as to respond to the operating conditions thereof and control said flow accordingly.

2. . A control device according to claim 1, wherein adjustable calibration means is connected to the other of the passages and is operable to regulate the flow rate through said other passage.

3. A control device according to claim 1 or 2, wherein adjustable calibration means is connected to said one passage and is operable to regulate the flow rate therethrough when said valve means is at or near the fully open condition.

4. A control device according to claim 2 or 3, wherein the or each said calibration means includes a screw device which can be protruded into the respective said passage to limit flow therethrough and which is adjustable to vary the degree of said protrusion.

5. A control device according to claim 4, wherein said one passage calibration means is located downstream of said valve means.

6. A control device according to any preceding claim, wherein said device includes a hollow body having an inlet port and an outlet port, and said two passages extend through at least part of said body and each has its opposite ends connected to said inlet port and said outlet port respectively.

7. A control device according to any preceding claim, wherein said valve means includes a member having a body portion and a piston portion which are arranged in spaced but interconnected relationship, biasing means urging said member towards a fully open condition of said valve means at which said body and piston portions are located on respective opposite sides of said one passage, and pressure responsive means connected to said piston portion and being ~5W- operable to move said member against biasing means 7- 20582: said body portion fully or partially within said one passage.

8. A control device according to claim 7, wherein said i pressure responsive means includes a chamber which is connectable to said engine intake manifold, and a flexible diaphragm which forms a wall of said chamber and is connected to said member to cause said movement thereof.

9. In an internal combustion engine, an improvement comprising a control device according to any preceding claim 10 having a common inlet and a common outlet for said two " - passages, said inlet being connected to said source of | gaseous fuel, and said outlet being connected to the intake manifoldj of said engine.

10. A gaseous fuel control device substantially as herein particularly described with reference to what is shown in the accompanying drawings. Th&35tK DAY OF Tebv I? A. J. PARK & SON PER ■ agei-iT" fon, THE ArP!.'CANTS \ , 5 sw -8-