EP2158396A1

EP2158396A1 - Fuel delivery system

Info

Publication number: EP2158396A1
Application number: EP07815411A
Authority: EP
Inventors: James Richard Hunt
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-10-31
Filing date: 2007-10-22
Publication date: 2010-03-03
Also published as: AU2007314133A1; WO2008052248A1; CN101595293A

Abstract

A fuel delivery system is disclosed which has a housing (3) having a chamber (310) in which an injector (20) is located. A liquid gas inlet (301) supplies liquid gas to chamber (310) so the liquid gas can in turn be supplied to the injector (20) for injection into a cylinder of an engine. A transfer tube (315) supplies liquid gas from the chamber (310) which is not ejected by the injector (20) to a vapour injector (313) which forms a regulator for regulating the pressure of the liquid gas and any vapour in the chamber (310). The use of the injector (313) as the pressure regulator overcomes problems associated with icing in the vicinity of the regulator which may otherwise impair proper operation of the regulator.

Description

FUEL DELIVERY SYSTEM

Field of the Invention

This invention relates to a fuel delivery system and, in particular, to an improvement to the fuel injector system disclosed in International Application PCT/AU2003/000971 (WO2004/018862) .

Background of the Invention The above International application discloses a fuel delivery system for delivering liquid gas fuel such as liquid petroleum gas to an engine. In particular, the system of the above International application discloses the delivery of such a fuel concurrently with diesel fuel to the engine.

The system of the aforesaid International application includes a block which has a bore for receiving a liquid injector for injecting the liquid gas fuel. The block includes a labyrinth path so that liquid gas fuel can pass through the path to cool the block. The liquid gas fuel is also supplied to a chamber surrounding the liquid injector to maintain the liquid injector and the liquid gas fuel cool so the liquid gas fuel remains in the liquid state for ejection by the injector. A pressure regulator is provided downstream of the injector for regulating the pressure in the chamber so the pressure in the chamber is about the same as the pressure of the supply for providing the liquid gas and for maintaining the pressure downstream of the regulator relatively low compared to the pressure in the chamber. The pressure regulator comprises diaphragms , a spring, a pin and a seal for seating on a seat.

The system of the aforesaid International application operates extremely well under most conditions . However , it has recently been found that if there is an unusually large amount of water in the liquid gas fuel, ice can form in the regulator . This prevents proper operation of the regulator with the result that cycling of the phase of the fuel takes place between a vapour and a liquid state at the injector, which prevents proper ejection of fuel in the liquid state. Thus, the injector may not work properly to provide fuel to the engine.

Summary of the Invention The object of the invention is to overcome the above problem.

The invention may be said to reside in a fuel delivery system for delivering liquid gas fuel to a cylinder of an engine, comprising: a housing; a chamber in the housing for receiving an injector which includes an opening for enabling liquid gas to be supplied to the injector for ejection from the injector; a liquid gas inlet communicating with the chamber for introducing liquid gas into the chamber and into the injector when the injector is located in the chamber; an outlet from the chamber; a passage through the housing through which liquid gas can flow; and a pressure regulator for regulating the pressure of vapour and/or liquid gas within the chamber, the pressure regulator comprising a regulator injector arranged downstream of the chamber.

Thus, by using the injector as the pressure regulator, no icing at the point of the pressure drop takes place if there is an unusual amount of water in the liquid gas fuel, thereby ensuring that pressure is properly maintained in the chamber and the liquid injector operates properly to supply fuel to the engine . The reason for this is that the regulator injector is operated to positively open and close the injector to reduce the pressure in the chamber by application of electronic signals to the injector. Because the injector is positively opened and closed, it does not tend to remain open, as is the case with conventional diaphragm-type regulators which leave a small opening which can easily ice up. Furtherstill, because of the nature of the injector and the positive opening and closing, the pressure drop occurs some distance from the injector outlet and therefore, there is generally a large amount of pressure at the injector which prevents the formation of ice which can impair operation of the injector.

Preferably the housing includes a labyrinth path for receiving liquid gas fuel in the liquid and/or vapour state for further facilitating cooling of the housing and therefore the injector and the fuel in the injector so the fuel remains in the liquid state in the chamber for ejection by the liquid injector.

Preferably the regulator injector supplies the vapour and/or liquid gas fuel to the labyrinth .

Preferably the chamber, the regulator injector and the labyrinth path form a flow path in the housing for cooling the housing and therefore the liquid gas in the chamber and the liquid injector to maintain the liquid gas in the liquid state for ejection by the liquid injector.

Preferably the housing is in the form of a block.

Preferably the path has an inlet and a fuel reservoir upstream of the chamber, a transfer tube for supplying liquid gas and/or vapour from the chamber to the regulator injector, and an expansion chamber between the outlet of the regulator injector and the labyrinth path. Preferably the labyrinth path has an outlet from which vapour and/or liquid gas fuel can be supplied to a vapour block for converting the fuel fully to the vapour state for ejection as vapour to the engine.

Preferably the regulator injector comprises a vapour injector.

However, in other embodiments the regulator injector could be any other type of injector.

Preferably the system further comprises a diesel injector for concurrently supplying diesel fuel to the engine .

Description of the Drawings

A preferred embodiment of the invention will be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a schematic diagram of the preferred embodiment of the invention;

Figure 2 is a detailed view of the preferred embodiment of the invention;

Figure 3 is a top cross-sectional view showing four injection devices correctly aligned with the inlet ports of the cylinder head and attached to the inlet manifold according to the preferred embodiment of the invention; and

Figure 4 is a detailed view of part of the embodiment of Figure 2 showing the complete structural details of that part of Figure 2.

Description of the Preferred Embodiment

With reference to Figure 1 liquid petroleum gas tank 12 supplies liquid petroleum gas via tank lock 14 to service line 16 and onto inline filter 4. The filtered liquid petroleum gas is then conveyed through service line 37 to distribution block 38. From the distribution block 38 the liquefied petroleum gas liquid flows through insulated delivery lines 39 to injector housings 3 (shown in more detail in Figure 4) .

With reference to Figure 2 the liquefied petroleum gas from lines 39 enters housing 3, which will be described in detail with reference to Figure 4. The housing 3 has a liquid injector 20 for supplying liquid petroleum gas to engine Ξ .

With liquid at injector 20 and a pulse width supplied from ECU 70 to injector 20 the liquid liquefied petroleum gas travels through the injector 20 and is ejected into manifold 32 (see Figure 3) , with the spray directed towards inlet port 29 (see Figure 3) . The injection of the liquefied petroleum gas is timed by the ECU 70 such that the pulse occurs after the closing of exhaust valve 133 (see Figure 3) and before the closing of the inlet valve 132 (see Figure 3) , such that the downward action of piston 131 (see Figure 3) can draw into engine E, all of the liquefied petroleum gas ejected with no blow-by passed exhaust valve 133.

The liquefied gas in the housing 3 which does not enter injector 20, and which can be in a vapour or liquid state, leaves the housing 3 through conduit 240. The conduit 240 passes through a bleed gas heater 250. The bleed gas heater 250 has an inlet 251a and an outlet 252a which can be connected in an engine cooling water conduit so that engine cooling water which is at a temperature of about 7O⁰C passes through the heater 250 to supply heat to the heater 250 and, in particular, heat to the part of the conduit 240 which is inside the heater 250. Thus, any liquid gas which passes through the conduit 240 is heated and therefore converts to a vapour state if not already in a vapour state. The conduit 240 is connected to a bleed injector 260 which is designed to eject gas rather than liquid, and the injector 260 injects vapour into the inlet manifold 32, as is shown in Figure 2. The bleed injector 260 is controlled by the ECU 70 via pulses received on line 253. The pulses on the line 253, like the pulses on line 86, are timed such that the injector 260 is actuated when the inlet valve 132 is open and the exhaust valve 133 is closed, so that the liquid petroleum gas in vapour state is supplied to the engine E together with the liquid ejected from the injector 20. Thus, the supply of the vapour is controlled in the same manner as the liquid supply and therefore blow-through of vapour through the engine is prevented or at least greatly reduced. The injectors 260 are sized and the pulses supplied on line 253 of such a length that the desired amount of gas is injected into the engine such that emissions are not adversely affected and, at the same time, the cooling effect provided by the passage of liquid gas through the inlet 11, the housing 203 and the conduit 240 does not adversely affect the cooling of the injector 20.

The bleed gas heater 250 ensures that no liquid gas in the liquid state reaches the bleed injector 260, as this would alter the mixture due to the fuel density difference between liquid and gaseous liquid petroleum gas.

The heat supplied by the bleed gas heater 250 is preferably sufficient to ensure that the temperature is well above the liquid petroleum gas vaporisation point and relatively stable.

Figures 2 and 3 also show diesel injector 171 for supplying diesel fuel to the cylinder of the engine E concurrently with the supply of liquid petroleum gas via the injector 20 and the injector 260. Thus, by supplying fuel in the form of liquid petroleum gas from the injectors 20 and 260, the amount of diesel fuel which is required can be reduced, thereby increasing fuel economy compared to situations which would occur when only diesel fuel is supplied via the diesel injector 171. Furtherstill, by ensuring that the liquid gas which is bubbled off in the housing 203 and used to cool the injector 20 is again delivered to the engine in the form of vapour during the cycle of the engine when the exhaust valve 133 is closed and the inlet valve 132 is open, ensures that that fuel is efficiently used thereby increasing power, which means that not so much throttle pressure is required, thereby further reducing fuel. The fact that the fuel is supplied in this manner also prevents blow-through, which would not only waste the fuel, but also may well increase emissions to an undesirable level.

Figure 4 shows details of the housing 3. As shown in Figure 4, the housing 3 is in the form of a block 300 formed from metal such as aluminium. The block 300 has an lpg inlet 301 which receives the lpg fuel from line 39.

The inlet 301 connects with reservoir 380.

An injector chamber 310 is also formed in the block 300 by a large diameter bore which is made through the face 309. The reservoir 380 has an outlet 311 which opens into a lower portion of the injector chamber 310. The injector chamber 310 has a passage 312 which extends from an upper portion of the chamber 310 to a transfer tube 315. The transfer tube 315 connects with a vapour injector 313 which is located in a bore 320 formed in the block 300.

The vapour injector 313 forms a regulator for regulating the pressure of liquid petroleum gas and/or vapour in the chamber 310 which maintains the injector 20 cool and also the liquid petroleum gas in the chamber 310 cool, so that the liquid does not bubble or evaporate in the injector 20 and is therefore maintained in the liquid state for proper ejection by the liquid injector 20 to the engine E. Because the pressure is maintained in the chamber 310 by the regulator injector 313 which is in the form of a vapour injector, icing does not occur at the point of pressure drop if there is excessive water in the liquid petroleum gas fuel. Therefore, liquid petroleum gas fuel properly flows to the injector 20 and from the passage 312 to the outlet 317 to maintain the required pressure within the chamber 310 and the liquid phase of the liquid petroleum gas in the injector 20 for ejection from the injector 20. The injector 313 has an outlet 314 which supplies fuel to a first outlet bore 315 which forms an expansion chamber and which joins a labyrinth passage 316 which passes through the block 300. The labyrinth passage 316 joins an outlet 317 which couples to the conduit 240 described with reference to Figures 1 to 3.

The various parts of the passages 380, 315 and 316 are formed by drilling bores in the block and blocking the bores where necessary by dowels (not shown) or by forming the bores in a surface of the block 300, and then closing the surface with a cover plate (not shown) . A cover plate (not shown) may also be used to close the face 309 to securely locate the injector 20 within the chamber 310.

Liquid petroleum gas is delivered through the inlet 301 into the chamber 310. The liquid petroleum gas is under high pressure. Injector 20 is located in chamber 310 and is a commercially available injector which includes a plurality of inlet orifices 330 about its periphery. The orifices 330 are arranged so that they are generally in alignment with the outlet 311 from reservoir 380 so that liquid petroleum gas in a liquid state can enter the lowermost orifice 330 for ejection from the injector 20. Signals are supplied to the terminal 20a of the injector 20 from ECU 70 to operate the injector 20.

Any liquid petroleum gas which converts to vapour state or bubbles in the vicinity of the outlet 311 and chamber 310 will generally flow around the injector 20 towards the upper part of the chamber 310 and into outlet bore 312. The injector 20 is provided with a gauze covering (not shown) about the orifices 330 which also facilitates in movement of the bubbles around the periphery of the injector 20 and not into the orifices 330. Thus, the fuel which enters the injector 20 is in the liquid state ready for injection and not vapour or bubbles which may be form and which, if they entered the injector 20, would impair operation of the injector 20. The outlet bore 312 communicates with regulator injector 313 to maintain pressure within the chamber 310. However, as the pressure in the chamber 310 and bore 312 increase, the regulator injector 313 is opened by supply of a signal to terminal

391 to enable the liquid petroleum gas in vapour or bubble state to pass through the regulator injector 313 by ejection from the regulator injector 313, to outlet passage 315, and then through the labyrinth 316 to outlet passage 317 and then to the heater 250 for supply to the engine in vapour state, as previously described with reference to Figures 1 to 3.

The regulator 313 therefore serves to maintain a high pressure region in the chamber 310 which connects back through inlet 301 to tank 12. Thus, the regulator 313 maintains the pressure within the chamber 310 as close to supply tank pressure as is possible. This facilitates maintenance of the liquid petroleum gas primarily in a liquid state for injection by the injector 20. This, together with the cooling of the block 300 by the passage of the liquid petroleum gas from the inlet 301 to outlet 317, serve to minimise boiling of the liquid petroleum gas in the block 300 so the flow of liquid petroleum gas to the injector 20 and its ejection from the injector 20 is not impaired. However, as noted above, any bubbles or vapour which is caused by boiling of the liquid petroleum gas will flow around the injector 20 to passage 312, and the increase in pressure caused by this vaporisation will open the regulator 313 to allow the vapour and bubble mixture, and therefore the excess pressure to bleed off through the regulator 313 until the pressure drops and the regulator 313 closes .

The pressure on the downstream side of the regulator 313 is considerably less than that in the chamber 310, and the regulator 313 also maintains the low pressure environment on the downstream side so that any liquid petroleum gas which does pass through the regulator 313 can fully vaporise because of the relatively low pressure environment on the downstream side of the regulator 313 compared to the pressure environment within the chamber

310. The passage of the liquid petroleum gas through the outlet 317 and its vaporisation facilitates cooling of the block 300 to, as is noted above, maintain the liquid petroleum gas on the upstream side of the regulator 313, primarily in the liquid state.

As explained with reference to Figures 1 to 3 , the vapour is supplied to heater 250 through conduit 240 and any liquid petroleum gas which is not already in the vapour state will be vaporised because of the heat supplied to the liquid petroleum gas by the heater 250. The liquid petroleum gas in the vapour state is then supplied to the bleed injector 260 for introduction into the inlet manifold of the engine Ξ .

The regulator 313 is operated by applying signals to the terminal 391 as explained above. Those signals can be derived from the ECU 70 in accordance with a fuel mapping plan programmed into the ECU 70 which is also used to fire the injector 20 to deliver liquid gas fuel to the engine

E. However, in other embodiments the regulator 313 can be opened and closed by electrical signals which are supplied in response to pressure measurements made by a pressure sensor (not shown) in the chamber 310 so that when the pressure reaches a predetermined level, the injector 20 is opened then closed to allow fuel to exit the regulator 313 and pass to the block 250.

Since modifications within the spirit and scope of the invention may readily be effected by persons skilled within the art, it is to be understood that this invention is not limited to the particular embodiment described by way of example hereinabove.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise", or variations such as "comprises" or "comprising", is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

1. A fuel delivery system for delivering liquid gas fuel to a cylinder of an engine, comprising: a housing; a chamber in the housing for receiving an injector which includes an opening for enabling liquid gas to be supplied to the injector for ejection from the injector; a liquid gas inlet communicating with the chamber for introducing liquid gas into the chamber and into the injector when the injector is located in the chamber; an outlet from the chamber; a passage through the housing through which liquid gas can flow; and a pressure regulator for regulating the pressure of vapour and/or liquid gas within the chamber, the pressure regulator comprising a regulator injector arranged downstream of the chamber.

2. The fuel delivery system of claim 1 wherein the housing includes a labyrinth path for receiving liquid gas fuel in the liquid and/or vapour state for further facilitating cooling of the housing and therefore the injector and the fuel in the injector so the fuel remains in the liquid state in the chamber for ejection by the liquid injector.

3. The fuel delivery system of claim 1 wherein the regulator injector supplies the vapour and/or liquid gas fuel to the labyrinth.

4. The fuel delivery system of claim 1 wherein the chamber, the regulator injector and the labyrinth path form a flow path in the housing for cooling the housing and therefore the liquid gas in the chamber and the liquid injector to maintain the liquid gas in the liquid state for ejection by the liquid injector.

5. The fuel delivery system of claim 1 wherein the housing is in the form of a block .

6. The fuel delivery system of claim 2 wherein the path has an inlet and a fuel reservoir upstream of the chamber, a transfer tube for supplying liquid gas and/or vapour from the chamber to the regulator injector, and an expansion chamber between the outlet of the regulator injector and the labyrinth path.

7. The fuel delivery system of claim 2 wherein the labyrinth path has an outlet from which vapour and/or liquid gas fuel can be supplied to a vapour block for converting the fuel fully to the vapour state for ejection as vapour to the engine .

8. The fuel delivery system of claim 1 wherein the regulator injector comprises a vapour injector.

9. The fuel delivery system of claim 1 wherein the system further comprises a diesel injector for concurrently supplying diesel fuel to the engine.