GB2053354A

GB2053354A - Diesel fuel supply system

Info

Publication number: GB2053354A
Application number: GB8022988A
Authority: GB
Original assignee: Thomson International Co
Current assignee: Thomson International Co
Priority date: 1979-07-13
Filing date: 1980-07-14
Publication date: 1981-02-04
Also published as: GB2053354B; FR2461113B1; JPH0133662B2; DE3025865A1; FR2461113A1; CA1136501A; JPS5618058A

Abstract

A mixing valve 30 includes a housing provided with a plurality of flow passages therethrough. A thermally responsive valve member 84 is located in a main passage 80 interconnecting a fuel supply line 28 from a fuel tank and a fuel supply conduit 38 leading via a filter to the fuel pump and injectors of the diesel engine. The valve member 84 opens at low temperatures to permit unused fuel which has been heated by the engine and which flows back from the injectors to the valve 30 via a return conduit 62 to pass via a passage 96 to mix with the fuel flowing through the passage 80 towards the filter. The fuel passing through the filter is thereby kept warm enough to avoid clogging of the filter with ice crystals and wax. A float valve member 104, 106 prevents air which flows from the injectors with the unused fuel from mixing with the fuel from the tank. <IMAGE>

Description

SPECIFICATION Diesel fuel control valve and system In most diesel engine systems there is a filter device through which fuel must flow to reach the engine. When the engine apparatus is subjected to temperatures in the region of zero degrees Fahrenheit and lower, there is a tendency for ice crystals and wax to form in the diesel fuel. Such conditions cause clogging of the fuel filter device.

Another problem which exists in a conventional diesel engine apparatus relates to the fact that some of the fuel pumped to the engine is not used and the excess fuel which flows from the engine contains a small quantity of gas which is ordinarily vented from the fuel in the fuel tank as the excess fuel returns to the fuel tank.

Various methods have been employed in an attempt to overcome these problems. For example, the conventional diesel fuel oil is mixed with another fuel oil in order to produce a fuel which will flow better in cold weather, even though other characteristics of the fuel may be less desirable. This has not been found to be satisfactory and adds to the expense of the fuel.

Heat exchanger devices have been employed to heat the diesel fuel. However, such devices may not provide heat to the fuel until a significant period of time has elapsed, and therefore fuel filter clogging may occur with initial operation.

Another system which has been employed is that of a fuel tank which has a mixing zone with a temperature responsive valve controlling flow of fuel with respect to the mixing zone. Such a system requires a special fuel tank.

It is therefore an object of this invention to provide a diesel fuel control valve and system which delivers fuel to a diesel engine at a proper temperature when the diesel engine apparatus is exposed to substantially any outdoor temperature, either cold or warm.

This invention comprises diesel engine fuel control apparatus for use in a diesel system which has a diesel engine, a fuel reservoir, fuel conduit means for providing excess quantities of fuel to the diesel engine, and fuel return means for conducting unused fuel from the diesel engine.

The fuel control device includes thermally responsive fuel control valve means which controls the mixing of fuel which flows from the diesel engine with fuel flowing from the fuel reservoir. The fuel control device also includes valve means for venting air which flows from the diesel engine with the unused fuel. Therefore, the air is prevented from flowing back to the diesel engine with the mixed fuel. Reference will now be made to the accompanying drawings, in which: FIG. 1 is a diagrammatic view showing a diesel fuel control valve and system embodying this invention in combination with a diesel engine apparatus; and FIG. 2 is a cross-sectional diagrammatic type of view, drawn on a much larger scale than Fig. 1, showing a diesel fuel control valve embodying this invention.

FIG. 1 shows a diesel engine 10 provided with a fuel pump 12 and a fuel filter 1 8. Diesel fuel is supplied to the engine 10 from a fuel tank 24.

A fuel supply conduit 28 extends from the tank 24 to a mixing valve 30 embodying this invention.

The fuel supply line 28 is joined to an inlet passage 34 within the mixing valve 30. A fuel supply conduit 38 is joined to an outlet passage 42 of the mixing valve 30 and extends to the fuel filter 1 8. A conduit 46 extends from the fuel filter 18 to the fuel pump 12, and a conduit 52 extends from the fuel pump 12 to a set of fuel injectors 56 of the engine 10. A conduit 62 leads from the fuel injectors 56 to an inlet passage 66 of the mixing valve 30. A fuel return conduit 72 is joined to an outlet passage 76 of the mixing valve 30 and is also joined to the fuel tank 24.

Between the inlet passage 34 and the outlet passage 42 within the mixing valve 30 is a main passage 80 which is in communication with the inlet passage 34 and the outlet passage 42.

Within the main passage 80 is a thermally responsive actuator device 84 which is provided with a container 84a and a stem 84b. The thermally responsive actuator device 84 is preferably of a type in which the stem 84b extends into the container 84a within which there is a quantity of thermally responsive expansiblecontractible material. The thermally responsive material within the container 84a expands significantly in volume when subjected to temperatures above a given predetermined value.

Such expansion causes relative movement between the container 84a and the stem 84b. The stem 84b is shown threadedly adjustably attached to a wall 88 of the mixing valve 30, and the position of the container 84a with respect to the connecting passage 96 is adjustable by threaded movement of the stem 84b. Encompassing the container 84a is a spring 90 which engages the container 84a and also engages an annular seal member 92 which is positioned within an auxiliary passage 94. The auxiliary passage 94 is in communication with a connecting passage 96.

The connecting passage 96 is provided with a valve seat 98 which is within a port 99. The port 99 is in communication with a chamber 100. The chamber 100 is in communication with the inlet passage 66 and the outlet passage 76.

Within the chamber 100 is a float member or buoyant member 104 which has a closure element 106 at least partially within the port 99.

The fuel pump 12 creates negative pressure conditions which cause fuel to flow from the tank 24, through the fuel supply conduit 28, and into the main passage 80 of the mixing valve 30, through the inlet passage 34 thereof. The fuel then flows through the main passage 80 and outwardly from the mixing valve 30 through the outlet passage 42. The fuel then flows through the fuel supply conduit 38 through the fuel filter 18, through the conduit 46 to the fuel pump 12, and flows from the fuel pump 12 through the conduit 52 to the fuel injectors 56 of the diesel engine 10.

Some of the fuel provides combustion in the diesel engine 10, and some of the fuel flows from the injectors 56 through the conduit 62 to the mixing valve 30 and into the inlet passage 66 thereof. Air is found in the excess fuel which flows from the diesel engine. The fuel and air then flows through the conduit 62 into the chamber 100. This fuel has been heated by the diesel engine 10.

It is important that the air which flows from the diesel engine not be permitted to return to the diesel engine.

The closure element 106 of the float 104 engages the valve seat 98 and closes the port 99 until there is a sufficient volume of fuel within the chamber 100 to cause the float 104 to float within the chamber 100. Therefore, air flowing from the engine 10 through the conduit 62 is not permitted to flow into the connecting passage 96.

The air flows outwardly from the chamber 100, through the outlet passage 76 and then flows to the fuel tank 24 through the fuel return conduit 72. The air is then vented from the tank 24 through any suitable vent means, not shown.

When the float 104 floats in the fuel within the chamber 100 as illustrated in Fig. 2, the closure element 106 is spaced from the valve seat 98.

Therefore, heated fuel flows from the chamber 100 through the port 99, through the connecting passage 96 and into the main passage 80. This heated fuel is mixed with fuel flowing into the main passage 80 from the fuel tank 24.

Thus, as operation of the diesel engine 10 is initiated, heated fuel from the engine 10 is mixed with fuel flowing from the tank 24. Therefore, fuel flowing through the filter 18 to the engine 10, has a temperature sufficiently high that clogging of the filter 1 8 does not occur.

This mixing action continues until the temperature of the fuel engaging the thermally responsive actuator 84 reaches a predetermined value. When this occurs, the container 84a moves in a direction from the stem 84b and toward the connecting passage 96. Thus, the volume of the fuel flowing from the chamber 100 to the main passage 80 is gradually reduced, and the portion of the fuel flowing from the tank 24 into the main passage 80 gradually increases. If the temperature of the fuel engaging the thermally responsive actuator 84 increases to a higher predetermined value, the container 84a moves into a position to close the connecting passage 96, and no fuel flows from the chamber 100 into the main passage 80.Thus, under these conditions all of the fuel flowing through the main passage 80 to the fuel filter 18 and to the engine 10 is fuel flowing directly from the tank 24.

When the temperatures to which the thermally responsive actuator device 84 are reduced to a predetermined value, the thermally responsive material within the container 84a reduces in volume, and the spring 90 forces the container 84a to move toward the wall 88. Thus, the connecting passage 96 is partially or entirely opened for flow of fuel therethrough to the main passage 80, and mixing of heated fuel with fuel from the tank 24 is resumed.

Thus, it is understood that the diesel fuel control valve and system embodying this invention provides fuel which has a sufficient temperature to avoid waxing and clogging of the fuel filter 1 8.

Furthermore, the control valve embodying this invention effectively limits the temperature of fuel flow to the diesel engine, and does not permit return flow of air to the engine.

Claims

1. Diesel fuel control apparatus for a diesel fuel system provided with fuel supply means, a diesel engine which uses a portion of fuel flowing thereto from the fuel supply means and in which a portioh of the fuel which flows to the engine is not used by the diesel engine and flows therefrom as excess fuel, air also flowing from the engine with the excess fuel, the diesel fuel system also being provided with conduit means joined to the diesel engine and to the fuel supply means for flow of fuel between the fuel supply means and the diesel engine, said apparatus comprising:: a fuel control device including a housing provided with fuel flow passage means therein, to receive fuel which, in operation, flows thereinto from the fuel supply means and from the diesel engine, and valve means within the fuel flow passage means which, in operation, controls the mixing of fuel which flows to the fuel control device from the fuel supply means with unused excess fuel which flows to the fuel control device from the diesel engine, the mixture of fuel, in operation, flowing from the fuel control device to the diesel engine.

2. The diesel fuel control apparatus as claimed in Claim 1, in which the valve means includes thermally responsive valve means.

3. The diesel fuel control apparatus as claimed in Claim 1, in which the valve means includes buoyant controlled valve means.

4. The diesel fuel control apparatus as claimed in Claim 1, in which the valve means includes thermally responsive valve means and buoyant controlled valve means.

5. The diesel fuel control apparatus as claimed in Claim 2, in which the thermally responsive valve means comprises a thermally responsive actuator which includes a stem and a rigid container of thermally expansive material, the stem being secured to the housing and the container being movable with respect to the stem, the thermally responsive valve means including means for controlling flow of fuel through the fuel passage means.

6. The diesel fuel control apparatus as claimed in Claim 2, in which the thermally responsive valve means includes thermally responsive valve mechanism for blending excess fuel received from the diesel engine with fuel received from the fuel supply means in accordance with the temperature of the blended fuel.

7. The diesel fuel control apparatus of Claim 1, in which the housing is provided with a first passage for communication between the fuel supply means and the diesel engine for flow of fuel from the fuel supply means tithe diesel engine, a second passage for communication between the diesel engine and the fuel supply means for flow of excess fuel and air from the diesel engine to the fuel supply means, and a connecting passage between the first passage and the second passage for flow of fuel from the second passage to the first passage, the second passage including a chamber, a float member within the chamber, a valve member carried by the float member and movable to close and to open the connecting passage in accordance with the position of the float member within the chamber.

8. The diesel fuel control apparatus of Claim 1, in which the housing is provided with a first passage for communication between the fuel supply means and the diesel engine for flow of fuel from the fuel supply means to the diesel engine, a second passage for communication between the diesel engine and the fuel supply means for flow of excess fuel and air from the diesel engine to the fuel supply means, and a connecting passage between the first passage and the second passage for flow of fuel from the second passage to the first passage, the valve means controlling flow of fuel through the connecting passage.

9. The diesel fuel control apparatus of Claim 1, in which the housing is provided with a first passage for communication between the fuel supply means and the diesel engine for flow of fuel from the fuel supply means to the diesel engine, a second passage for communication between the diesel engine and the fuel supply means for flow of excess fuel and air from the diesel engine to the fuel supply means, and a connecting passage between the first passage and the second passage, for flow of fuel from the second passage to the first passage, the valve means including buoyant control valve means and thermally responsive valve means controlling flow of fuel through the connecting passage.

10. The diesel fuel control apparatus of Claim 1, in which the housing is provided with a first passage for communication between the fuel supply means and the diesel engine for flow of fuel from the fuel supply means to the diesel engine, a second passage for communication between the diesel engine and the fuel supply means for flow of excess fuel and air from the diesel engine to the fuel supply means, and a connecting passage between the first passage and the second passage, for flow of fuel from the second passage to the first passage, the valve means including buoyant control means within the second passage, the buoyant control means including valve means operable to control flow of fuel through the connecting passage from the second passage to the first passage.

11. The diesel fuel control apparatus of Claim 1, in which the housing has a first passage therethrough and a second passage therethrough, and a connecting passage joining the first passage and the second passage, the diesel fuel system including a first conduit joining the fuel supply means to the first passage, a second conduit joining the first passage to the diesel engine, a third conduit joining the diesel engine to the second passage and a fourth conduit joining the second passage to the fuel supply means, thermally responsive valve means within the first passage of the housing and operable upon the connecting passage to control flow of fuel from the second passage to the first passage in accordance with the temperature of the fuel within the first passage.

12. The diesel fuel control apparatus of Claim 1, in which the housing has a first passage therethrough and a second passage therethrough, and a connecting passage joining the first passage and the second passage, the diesel fuel system including a first conduit joining the fuel supply means to the first passage, a second conduit joining the first passage to the diesel engine, a third conduit joining the diesel engine to the second passage and a fourth conduit joining the second passage to the fuel supply means, a buoyant control valve member within the second passage and operable to control flow of fuel through the connecting passage from the second passage to the first passage in accordance with the quantity of fuel in the second passage and in accordance with the position of the buoyant control valve member within the second passage, the buoyant control valve member thus permitting only fuel to flow through the connecting passage and preventing flow of air from the second passage to the first passage through the connecting passage.

13. Diesel fuel control apparatus substantially as hereinbefore described with reference to the accompanying drawings.

14. A diesel engine having a fuel system, and control apparatus as claimed in any preceding claim.