GB1567601A - Fuel economiser device for internal combustion engines - Google Patents

Description

(54) FUEL ECONOMISER DEVICE FOR INTERNAL COMBUR,GIÇS (71) We, E.S.L. (CORNWALL) LXTBD, a British Company, of Chapel Road, Tuckingmill, Camborne, Cornwall TR14 8QY, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a fuel economiser device for internal combustion engines of a type in which fuel feed to the engine is accomplished via a carburettor.

It is well known that the engine power required to maintain cruising conditions is very much less than the power required for accelerating the car from rest. Although carburettors are manufactured to modify the fuel/air mixture in dependence to some extent on the engine operating conditions this is necessarily a compromise between power requirements and economy requirements.

According to the present invention, there is provided a fuel economiser device for internal carburettor engines, comprising a duct section adapted to be inserted in an engine fuel induction system between the carburettor and the induction manifold for the through flow of fuel/air mixture, at least one opening in the wall of the duct section communicating with an air inlet, through a valve comprising a valve shutter housed within an elongate passageway which interconnects the said opening in the wall of the duct section and the air inlet, the valve shutter being displaceable, axially of the passageway, between two end positions in each of which it cooperates with a respective valve opening to close the said passage, the valve being open for intermediate positions of the shutter, and pressure responsive means operative, in use, when the duct section is inserted in an engine fuel induction system, to control the position of the valve shutter in dependence on the pressure prevailing in the induction system of the engine.

In this specification the term "vacuum" denotes a sub-atmospheric pressure, the vacuum being described as "high" or "low" according to whether the pressure is reduced by a greater or smaller amount, respectively, compared with atmospheric pressure.

We have found that a considerable fuel economy can be achieved if the fuel/air mixture supplied to the engine is diluted with additional air when under cruising conditions, so that a leaner mixture is upplied to the engine than would otherwise be the case. For this it is necessary to utilise a device which is able to sense when the engine is operating under cruising conditions. This sensing its effected by detecting the vacuum level in the induction system and operating the valve such that it is open only when the vacuum lies between a certain minimum and a certain maximum value.The valve is thus closed when the pressure sensed by the pressure responsive means is at either end of the range to which the pressure responsive means are sensitive, so that when the vacuum in the induction system is high, that is under engine idling conditions, the valve is closed: it is also closed when there is a low vacuum in the induction system, such as during development of maximum power. The valve opens, however, when the vacuum is intermediate the two extremes over a range which can be determined by experimentation to be that which corresponds to cruising conditions of the engine.

Thus a relatively richer mixture is supplied during very low and very high power conditions, when this mixture is essential, but a leaner mixture is supplied when the engine is cruising. Instead of using a double faced valve such as the one described above, which is closed at each end of a range of movements, a conventional valve such as a slide valve may be used.

Since the valve is closed under low or idling, and full power operating conditions, the economiser device is effective only during what may be termed cruise conditions, that is when a medium depression or vacuum prevails in the induction system.

The air inlet is preferably covered by a filter element such as a wire or plastics gauze and/or a paper element. The duct section of the fuel economiser device is in one embodiment provided with a plurality of said openings around its circumference, communicating with an air jacket surrounding the duct section, which air jacket communicates with the said passage. The said apertures preferably comprise axially elongate slots. Alternatively, and preferably, the said opening is a single opening which communicates via a passage in the duct section with the said air inlet, this passage in the duct section being substantially tangential to the interior wall of the duct section.

The pressure responsive means for operating the valve of the fuel economiser device preferably comprise a diaphragm forming one wall of a chamber to which a pressure derived from the induction system is applied in use of the device, the diaphragm being connected to the said valve shutter such that deflections of the diaphragm cause displacement of the valve shutter axially of the said passage.

In We preferred embodiment of the invention the valve shutter is connected to the diaphragm by an elongate member having an extension on the side of the valve shutter remote from the diaphragm, which extension is slidably located in the wall of the duct section and serves for the lateral location of the valve shutter within the passage.

The diaphragm chamber, in one embodiment, is put in communication with the induction manifold by separate communication pipes, but in the preferred embodiment the said elongate member comprises a tube which opens at one end into the said diaphragm chamber and at the other end into a passage communicating with the interior of the said duct section whereby to communicate the pressure within the duct section to the said diaphragm chamber Two embodiments of the invention will now be more particularly described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic cross section through a fuel economiser device formed as one embodiment of the invention; Figure 2 is a partial section through the device shown in Figure 1, taken on the line II-II of Figure 1; and Figure 3 is a diagrammatic cross section through a fuel economiser device formed as a second embodiment of the invention.

The device shown in the drawings has a die-cast body 1 formed with a short duct section 2 and two fixing flanges 3 by means of which the body 1 can be bolted to an induction manifold of an internal combustion carburettor engine, downstream of the carburettor, so that the duct section 2 forms a continuation of the fuel/air mixture supply duct leading into the induction manifold from the carburettor.

The duct section 2 is formed by a cylindrical wall 4 having an internal diameter corresponding to the internal diameter of the fuel/air mixture supply duct of the engine to which the device is to be fitted.

The wall 4 is perforated around its entire circumference by a number of axially elongate apertures 5 (Figure 2) which communicate with a surrounding annular air jacket 6 formed within the body 1. The jacket 6 communicates with a passage 7 in the body 1, the passage 7 being closed at its end remote from the jacket 6 and communicating, near this closed end, with the atmosphere through a number of air inlet ports 8. The air inlet ports 8 are covered by a tubular gauze filter 9 which prevents the ingress of dust and other foreign matter into the passage 7.

A valve is arranged for displacement axially within the passage 7, the valve having a cylindrical stem 10 which is a sliding fit in a bore in the wall 4, and in a bore in the other end of the body 1. The valve has a valve shutter body 11 which is formed with opposite frusto-conical bevelled faces 12, 13. The faces 12, 13 cooperate with respective annular frusto-conical valve seats 14, 15 formed in the passage 7. In a neutral position of the valve, shown in Figure 1, the shutter 11 is clear of the two valve seats 14, 15, allowing air to flow through the inlet ports 8, the passage 7 and the apertures 5 into the duct section 2. The valve has an upper closed position in which the face 12 of the shutter 11 engages and seals against the seat 14, and a lower closed position in which the face 13 of the shutter 11 engages and seals against the lower seat 15.

To facilitate the manufacture of the device with the two internal bevelled valve seats 14, 15 the body 1 is preferably made in two parts which are screwed together, as shown in Figure 1, one of the parts being formed with the bevelled seat 15 and the other with the bevelled valve seat 14.

The valve shutter 11 is movable axially in the passage 7 by means of a fluid pressure actuator comprising, in this embodiment, a diaphragm capsule 16 surmounting the body 1 of the device. The diaphragm capsule 16 includes a flexible diaphragm 17 which is sealed and clamped around its periphery and which is supported by two central reinforcing washers 18a, 18b to which the valve plunger 10 is attached. The washer 1 8a is acted upon by a helical spring 19 which biases the valve so that at rest the shutter 11 is in its lower closed position, in contact with and pressed against the seat 15.

The capsule 16 is separted by the diaphragm 17 into two chambers, 16a, 16b and the chamber 16a which contains the biasing spring 19 is connected to the induction manifold of the engine, or some other point in the induction system, by a separate conduit pipe (not shown) which is connected to a hollow spigot 16c of the capsule 16, while the other chamber 1 6b of the capsule 16 is open to atmosphere.

In operation of the device, the valve shutter 11 is in one of its two closed positions, in engagement with the valve seat 14 or the valve seat 15, closing the valve, except under conditions of medium depression or vacuum in the induction system. when the valve occupies an intermediate open position as shown diagrammatically in Figures I and 2. Thus during engine starting, when there is very low manifold depression or vacuum, the biasing spring 19 will hold the valve shutter 11 in sealing engagement against the lower valve seat 15. Similarly, under full throttle conditions, when there is also very little manifold depression (low vacuum), the valve shutter 11 will occupy its lower (as viewed in Figure 1) closed position.Under engine idling conditions or on overrun conditions, however, when there is a high depression (high vacuum) in the induction manifold, the diaphragm 17 will be flexed upwardly in response to the reduction of pressure in the upper part of the capsule 16, and the valve shutter 11 will accordingly be lifted into sealing engagement with the upper valve seat 14, closing the valve.

Under conditions of medium deression or vacuum in the induction system of the engine, the valve shutter 11 is held in an intermediate position so that supplementary air can enter the duct section 2 through the slot apertures 5 to dilute the fuel/air mixture passing into the engine. In a typical practical example the fuel/air mixture supplied to the engine under normal cruising conditions would have a fuell air ratio of 14:1, and with a device according to the present invention this mixture ratio would be increased to 17.2:1 under cruising conditions, thereby achieving a fuel economy of the order of 14%.

By introducing the supplementary air into the induction manifold around the periphery of the duct 2 it is arranged that an air flow passes over the internal surface of the induction manifold and picks up any fuel droplets deposited on the walls of the induction manifold, intimately mixing these fuel droplets with the air stream.

This further increases the efficiency with which the fuel is utilised in the cruising condition of the engine, and also reduces the emission of unburnt hydrocarbons in the engine exhaust.

To regulate the amount of supplementary air supplied under cruising conditions to the induction manifold the ports 8 are surrounded by a tubular sleeve 20 which at least partially covers the ports 8, the position of the sleeve 20 on the body of the device determining the effective flow cross section of the inlet ports 8.

It has been found that use of the device according to the invention makes it possible to run high compression engines on fuel of relatively low octane number (92), and thus more readily to comply with the Common Market regulation ECE 15, which stimplates a lead content in exhaust gases no greater than 0.04 milligrams per litre.

It should be noted that it has also been found that an adjustment to the ignition timing of an engine fitted with the fuel economiser device of the invention is necessary in order to secure the maximum fuel economy. Such an adjustment should be of 2" retardation from the previous setting.

In tests fuel economies of between 15% and 22% have been recorded on a range of vehicles to which no adjustment was made apart from the fitting of the device of the invention and the above noted ignition retardation of 2".

Referring now to Figure 3, there is shown an alternative embodiment which is selfcontained in that it is unnecessary to make use of separate communication pipes connecting it to the induction manifold since the sensing of pressure takes place internally. The general arrangement of the embodiment of Figure 2 is the same as in Figure 1, and therefore the same reference numerals will be used to refer to the same or corrsponding components.

The embodiment of Figure 3 differs from that of Figures 1 and 2 in that the valve stem 10, instead of being a solid rod, is a hollow tube open at both ends so that it permits communication between the diaphragm chamber 16a housing the spring 19 and the interior of the duct section 2.

The end of the valve stem 10 remote from the capsule 16 stops somewhat short of the interior of the duct section 2 and is provided with two mutually perpendicular transverse holes in which are housed two pins 22 forming a cruciform pin bearing for supporting the end of the valve stem 10 in the passage 7.

The body of the valve shutter 11, held on the valve stem 10 by a grub screw 1 la, is also different in the embodiment of Figure 3 from that of the embodiment of Figures 1 and 2 in that it is enlarged to limit the amount of movement from one end position to the other to a maximum of 0.4 inches. It has been found that the dimensions of the valve, particularly the valve movement, are of critical importance to satisfactory operation of the device.

At the other end of the valve stem 10, where it is attached to the diaphragm 17, the washer 1 8a in the diaphragm chamber 16a, which washer is contacted by the biasing spring 19, is formed with a deeply dished shape to assist in locating and guiding the spring 19. The chamber 1 6a is entirely closed, there being no connecting spigots such as are present in the embodiment of Figure 1; the diaphragm chamber 1 6b is open to the atmosphere through apertures 1 6d in the wall of the diaphragm capsule 16.

The duct section is also different in the embodiment of Figure 3 in that it has only a single passage 23 leading from the interior thereof to the passage 7, this passage 23 being tangential to the wall of the duct section 2 which has no air jacket like that of the embodiment of Figure 1. It has been found that this construction, whilst being much cheaper and easier to construct, is at the same time more effective since air entering the duct section tangentially through the passage 23 is caused to swirl increasing the turbulence of flow therein and therefore intimately mixing the newly entered air with the fuel/air mixture flowing along the duct.

In operation of this embodiment, the pressure within the interior of the duct section 2 is transmitted to the diaphragm chamber 16a to cause displacement of the diaphragm 17 and therefore of the valve stem 10 and valve shutter 11 in dependence on the relative pressures in the chambers 16a, 16b.

Assembly of the device to a motor vehicle engine is thus very simple, involving only the removal of the carburettor, fitting of the duct section 2 by means of the flanges 3 and refitting of the carburettor, no further changes to the engine being necessary apart from the above-mentioned retardation by 2" of the ignition timing.

It has been found, in practice, that there is no loss of power, which might be expected when accelerating, as the engine moves through tbe mid vacuum range from high vacuum to low vacuum in the induction system, since under these conditions, the manifold pressures lie in the same range as in cruising conditions. This is explained by the fact that the chamber 1 6a of the diaphragm capsule gradually becomes filled with fuel due, it is believed, to the condensation of fuel from the fuel/ air mixture drawn into the chamber 16a by the vacuum therein each time the engine is turned off. Thus upon displacement of the diaphragm in a sense such as to reduce the volume of the chamber 16a some fuel rich mixture is expelled into the duct section 2 through the hollow valve stem.This compensates to some extent for the weakening of the mixture in the induction manifold, due to the air flowing in through the air inlets 8, by adding fuel to this air prior to its entry into the duct section 2. Once displacement has taken place, of course, this effect stops, but if the condition was only transitory, such as would occur when accelerating hard from idling to full throttle conditions, as the vacuum in the manifold decreases continuously, and sometimes quite rapidly from a high vacuum at idling to a low vacuum at full throttle, through the range over which the valve is moved from its position in contact with the valve seat 15 to its position in contact with the valve seat 14, this effect serves as compensation for the temporary weakening of the mixture as the valve shutter moves from one end position to the other, thus avoiding an unwanted loss of power.

The dimensions of the embodiment of Figure 3 are preferably selected so that the valve is in the open position from a pressure of 4 pounds of vacuum and centralised over the vacuum range of 9 pounds to 11 pounds. As mentioned before the valve movement is limited to not more than 0.4 inches and the regulator sleeve 20 is adjusted so that the fuel/air ratio of a car is modified to 17.2:1 when the device of the present invention is fitted.

WHAT WE CLAIM IS: - 1. A fuel economiser device for internal combustion carburettor engines, comprising a duct section adapted to be inserted in an engine fuel induction system between the carburettor and the induction manifold for the through flow of fuel/air mixture, at least one opening in the wall of the duct section communicating with an air inlet, through a valve comprising a valve shutter housed within an elongate passageway which interconnects the said opening in the wall of the duct section and the air inlet, the valve shutter being displaceable, axially of the passageway, between two end positions in each of which it cooperates with a respective valve opening to close the said passage, the valve being open for intermediate positions of the shutter, and pressure responsive means operative, in use, when tbe duct section is inserted in an engine fuel induction system, to control the position of the valve shutter in dependence on the pressure prevailing in the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (12)

**WARNING** start of CLMS field may overlap end of DESC **. on the valve stem 10 by a grub screw 1 la, is also different in the embodiment of Figure 3 from that of the embodiment of Figures 1 and 2 in that it is enlarged to limit the amount of movement from one end position to the other to a maximum of 0.4 inches. It has been found that the dimensions of the valve, particularly the valve movement, are of critical importance to satisfactory operation of the device. At the other end of the valve stem 10, where it is attached to the diaphragm 17, the washer 1 8a in the diaphragm chamber 16a, which washer is contacted by the biasing spring 19, is formed with a deeply dished shape to assist in locating and guiding the spring 19. The chamber 1 6a is entirely closed, there being no connecting spigots such as are present in the embodiment of Figure 1; the diaphragm chamber 1 6b is open to the atmosphere through apertures 1 6d in the wall of the diaphragm capsule 16. The duct section is also different in the embodiment of Figure 3 in that it has only a single passage 23 leading from the interior thereof to the passage 7, this passage 23 being tangential to the wall of the duct section 2 which has no air jacket like that of the embodiment of Figure 1. It has been found that this construction, whilst being much cheaper and easier to construct, is at the same time more effective since air entering the duct section tangentially through the passage 23 is caused to swirl increasing the turbulence of flow therein and therefore intimately mixing the newly entered air with the fuel/air mixture flowing along the duct. In operation of this embodiment, the pressure within the interior of the duct section 2 is transmitted to the diaphragm chamber 16a to cause displacement of the diaphragm 17 and therefore of the valve stem 10 and valve shutter 11 in dependence on the relative pressures in the chambers 16a, 16b. Assembly of the device to a motor vehicle engine is thus very simple, involving only the removal of the carburettor, fitting of the duct section 2 by means of the flanges 3 and refitting of the carburettor, no further changes to the engine being necessary apart from the above-mentioned retardation by 2" of the ignition timing. It has been found, in practice, that there is no loss of power, which might be expected when accelerating, as the engine moves through tbe mid vacuum range from high vacuum to low vacuum in the induction system, since under these conditions, the manifold pressures lie in the same range as in cruising conditions. This is explained by the fact that the chamber 1 6a of the diaphragm capsule gradually becomes filled with fuel due, it is believed, to the condensation of fuel from the fuel/ air mixture drawn into the chamber 16a by the vacuum therein each time the engine is turned off. Thus upon displacement of the diaphragm in a sense such as to reduce the volume of the chamber 16a some fuel rich mixture is expelled into the duct section 2 through the hollow valve stem.This compensates to some extent for the weakening of the mixture in the induction manifold, due to the air flowing in through the air inlets 8, by adding fuel to this air prior to its entry into the duct section 2. Once displacement has taken place, of course, this effect stops, but if the condition was only transitory, such as would occur when accelerating hard from idling to full throttle conditions, as the vacuum in the manifold decreases continuously, and sometimes quite rapidly from a high vacuum at idling to a low vacuum at full throttle, through the range over which the valve is moved from its position in contact with the valve seat 15 to its position in contact with the valve seat 14, this effect serves as compensation for the temporary weakening of the mixture as the valve shutter moves from one end position to the other, thus avoiding an unwanted loss of power. The dimensions of the embodiment of Figure 3 are preferably selected so that the valve is in the open position from a pressure of 4 pounds of vacuum and centralised over the vacuum range of 9 pounds to 11 pounds. As mentioned before the valve movement is limited to not more than 0.4 inches and the regulator sleeve 20 is adjusted so that the fuel/air ratio of a car is modified to 17.2:1 when the device of the present invention is fitted. WHAT WE CLAIM IS: -

1. A fuel economiser device for internal combustion carburettor engines, comprising a duct section adapted to be inserted in an engine fuel induction system between the carburettor and the induction manifold for the through flow of fuel/air mixture, at least one opening in the wall of the duct section communicating with an air inlet, through a valve comprising a valve shutter housed within an elongate passageway which interconnects the said opening in the wall of the duct section and the air inlet, the valve shutter being displaceable, axially of the passageway, between two end positions in each of which it cooperates with a respective valve opening to close the said passage, the valve being open for intermediate positions of the shutter, and pressure responsive means operative, in use, when tbe duct section is inserted in an engine fuel induction system, to control the position of the valve shutter in dependence on the pressure prevailing in the

induction system of the engine.

2. A fuel economiser device as claimed in Claim 1, in which the air inlet is covered by a filter element.

3. A fuel economiser device as claimed in Claim 1 or Claim 2, in which the valve shutter is biased by a spring into one of its end positions in contact with one of the valve seats to close the valve.

4. A fuel economiser device as claimed in any of Claims 1 to 3, in which the duct section is provided with a plurality of said openings around its circumference, communicating with an air jacket surrounding the duct section and communicating with the said passage.

5. A fuel economiser device according to Claim 4, in which the said openings are in the form of axially elongate slots.

6. A fuel economiser device as claimed in any preceding claim, in which the said pressure responsive means comprise a diaphragm forming one wall of a chamber to which a pressure derived from the induction system is applied in use of the device, the diaphragm being connected to the said valve shutter such that deflections of the diaphragm cause displacement of the valve shutter axially of the said passage.

7. A fuel economiser device as claimed in Claim 6, in which the valve shutter is connected to the diaphragm by an elongate member having an extension on the side of the valve shutter remote from the diaphragm, which extension is slidably located in the wall of the duct section and serves for the lateral location of the valve shutter within the passage.

8. A fuel economiser device as claimed in Claim 7, in which the said elongate member comprises a tube which is open at both ends,one end communicating with the said diaphragm chamber and the other end communicating with the interior of the said duct section so that the pressure within the duct section is transferred also to the said diaphragm chamber.

9. A fuel economiser device as claimed in any preceding claim, in which there are provided means for restricting the size of the air inlet whereby to adjust the fuel/air mixture achieved when the device is in operation.

10. A fuel economiser device as claimed in any preceding claim, in which the said pressure responsive means operates, in use, to maintain the valve shutter between its end positions when the vacuum in the induction system lies between upper and lower limits which are respectively below and above the maximum and minimum values attained during operation of the engine from idling to full power.

11. A fuel economiser device as claimed in any of claims 1, 2 or 10, in which the valve is a slide valve.

12. A fuel economiser device substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings. ~