ES2360965T3 - DUAL FUEL SYSTEM. - Google Patents

Abstract

A set (10) of a dual fuel system to be installed with an internal combustion diesel engine that includes a fuel tank (43) for storing pressurized liquefied gas; a metering valve means (50) that can be operatively connected to the fuel tank (43) and is adapted to control the flow of the liquefied gas, in which the ratio between liquefied gas and diesel is predetermined; and a mixing chamber (28) that can be operatively connected to the metering valve (50) and is adapted to mix a metered flow of the liquefied gas and a metered flow of diesel to form a liquid fuel mixture, in which during its use the assembly can provide the mixture of liquid fuel to a combustion chamber of the diesel engine; characterized in that unburned excess fuel mixture is collected in an overflow tank (65) and returned to the mixing chamber (28) to be burned in the combustion chamber.

Description

Field of the Invention

The present invention is about diesel engines and fuel systems for diesel engines. The present invention has a particular, but not exclusive, application for use with trucks.

Background of the invention

Trucks, and particularly long-distance trucks, use large volumes of diesel fuel to transport goods. As the price of diesel increases, the cost of transporting goods also increases. Although at least part of the increase in costs is passed to the final consumer, market forces have caused the truck operator to absorb much of the additional costs, thereby reducing its profit margin. Consequently, alternative sources of fuel have been investigated.

LPG (Liquefied Petroleum Gas) has been used as an alternative fuel source for diesel engines. Although LPG is stored under pressure (approximately 1030 kPa) in the tank that holds the LPG in a liquid state, LPG is normally used in a gaseous state at pressures well below 965 kPa, which is the pressure required to maintain to LPG in a liquid state.

Diesel LPG has also been used in dual fuel systems. In US2005205021 a separate set of injectors introduces LPG gas into the combustion chamber, while in documents US5408957, US4520766, JP1318755 and GB1252458, LPG gas is mixed with air before introducing the air mixture into the combustion chamber.

The problem with using LPG as the sole source of fuel for diesel engines is that the engines need substantial modification to overcome the reduction in lubricating power with the use of LPG and the ability to provide LPG combustion. The modification of the engines is a considerable expense and voids the warranties of the engine manufacturer. Even with dual LPG and diesel fuel systems, diesel engines need to be modified to allow the introduction of LPG into the combustion chamber.

The reader is also referred to document DE 102004011414 which discloses a dual fuel system according to the preamble of claim 1.

Object of the invention

An object of the present invention is to provide an alternative dual fuel system that at least partially overcomes the problems mentioned above.

Summary of the Invention

The present invention arose from the taking of an alternative approach by understanding the effects of pressure on LPG and by developing a different solution to dual fuel systems using pressurized LPG without substantially modifying the diesel engine.

The present invention resides in a dual fuel system according to claim 1.

Preferably, the metering valve means includes a flow control valve operatively controlled by an electronic control panel. Preferably, the electronic control panel controls the flow control valve in response to information processed from the electronic control unit of the vehicle.

Preferably, the diesel fuel is pressurized before entering the mixing chamber. Preferably, the diesel fuel is pressurized by an in-line pump and the fuel is stored in a pressurized tank before being used. Preferably, the supply of pressurized diesel fuel to the mixing chamber is regulated by a flow control valve that is operatively controlled by an electronic control panel. Preferably, the electronic control panel is controlled by the electronic control unit of the vehicle that receives and processes information to provide a relevant signal to the electronic control panel.

Preferably, the liquefied gas is filtered before the metering valve with an in-line filter.

Preferably, the LPG tank, the metering valve means and the mixing chamber are connected by a gas line.

Preferably, the conduit between the LPG tank and the metering valve includes at least one valve that can be closed. In a preferred embodiment, there is a one-way check valve and a valve that can be closed inside the conduit between the LPG tank and the metering valve means.

The dual fuel assembly can be installed before the delivery of a vehicle with a diesel engine or it can be installed as an aftermarket kit.

The liquefied gas can be LPG, propane, natural gas or compressed natural gas.

Preferably, the liquefied gas tank stores LPG below a pressure of approximately 1030 kPa but above its vapor pressure of 550 kPa.

An internal combustion diesel engine may be provided with such a dual fuel system that includes

a first tank for storing pressurized liquefied gas;

a second tank for storing pressurized diesel;

a first metering valve means operatively connected to the first reservoir and adapted to control the flow of the liquefied gas;

a second metering valve means operatively connected to the second tank and adapted to control the flow of diesel;

a mixing chamber operatively connected to the first metering valve means and the second metering valve means, said mixing chamber being adapted to mix a metered flow of the liquefied gas and a metered flow of diesel to form a mixture of liquid fuel, Y

a distribution means for distributing the liquid fuel mixture to each internal combustion chamber, in which an engine processor controls the dosage of the fuels by regulating the respective metering valve means according to demand.

Preferably, the second tank receives pressurized diesel, by means of an in-line filter and a pump, from a diesel fuel tank.

Preferably, the second metering valve means includes a flow control valve operatively controlled by an electronic control panel. Preferably, the electronic control panel controls the flow control valve in response to information processed from the electronic control unit of the vehicle. The electronic control unit of the vehicle receives and processes an input with respect to the engine's fuel demand.

Preferably, there is an accelerometer means that measures the acceleration of the vehicle and if the vehicle is circulating

or not pending up or pending down. Preferably, the input of the accelerometer means operatively regulates the control valves of the flow of diesel and liquefied gas by means of the respective electronic control panels. Preferably, the accelerometer inputs are processed by the electronic control unit.

The ratio between LPG and diesel can vary between 50:50 and 90:10, respectively. More preferably, the ratio between LPG and diesel is approximately 70:30, respectively. Preferably, any relationship is adequate with the condition that the engine components do not wear out prematurely due to a lack of lubricating power and the manufacturer's warranties are not voided and the calorific value of the fuel is sufficient to allow the engine to produce an amount acceptable power and torque.

Preferably, the liquid fuel mixture is pumped to a common manifold that can operate under elevated pressure, so that the liquid fuel mixture remains in a liquid state. In memory, the term "common collector" includes common collectors and fuel channels. Preferably, the common manifold is connected to an injector by each combustion chamber and the fuel mixture is distributed to each of the injectors for combustion, according to the manufacturer's specifications.

Preferably, the fuel mixture is filtered before distribution in the common manifold.

According to the invention, excess unburned fuel mixture is collected in an overflow tank and returned to the mixing chamber to be burned in the combustion chamber. Preferably, the excess fuel mixture is returned by means of a fuel temperature sensor to a fuel pressure limiter, then to an overflow valve and a pressure limiting valve. Then, the excess fuel is preferably passed through a fuel cooler and kept under pressure in a pressurized tank for subsequent reintroduction into the mixing chamber.

Preferably, there is a separate conduit from the diesel tank to the supply pump and subsequently to the common manifold so that the engine can use diesel as the sole source of fuel.

Brief description of the drawings

In order that the present invention can be more easily understood and implemented, reference will now be made to the accompanying drawings in which:

Figure 1 is a schematic view of the preferred embodiment of the dual fuel system for diesel engines;

Figure 2 is a schematic view of the mixing chamber using Swage Lock metering valves as an alternative to the electronic control system; Y

Figure 3 is a schematic side view of the mixing chamber using Swage Lock metering valves as an alternative to the electronic control system.

Detailed description of the preferred embodiment

Referring to Figure 1, a dual fuel system 10 for a diesel engine for trucks is shown. Diesel from a pump of an atmospheric pressure service station is introduced into the tank 11. In a first conduit, diesel is removed from the tank 11 along the conduit 30 by means of an in-line filter 12 by means of a pump 13 fuel feed. The fuel feed pump 13 operates at a pressure of approximately 210 kPa. Inline filter 12 is a glass filter that removes contaminants. Subsequently, diesel fuel is pumped through the supply pump 15 to the common manifold 16 to enter the combustion chamber by means of injectors 18. With the first duct, diesel is used as the sole source of fuel to be burned in the combustion chamber of the engine.

In a second way, diesel is removed from the tank 11 by means of the secondary fuel feed pump 20 along the conduit 31. The diesel in the tank 11 is filtered by the in-line filter 12 as it is extracted by the secondary pump 20 Fuel supply From the secondary fuel supply pump 20, the diesel is passed through a check valve 17 to a secondary pressurized diesel tank 21. The pressure in the secondary pressurized tank 21 of diesel is maintained at approximately 689 kPa. The secondary pressurized tank 21 of diesel has a capacity of approximately 43 liters. The secondary pressurized diesel tank 21 has a pressure switch 22 that electrically controls the secondary fuel supply pump 20, thereby maintaining the desired pressure. The secondary pressurized diesel tank 21 also has a purge valve for purging any remaining air in the conduit 31 and in the secondary pressurized diesel tank 21. There is also a conduit 32 between the fuel supply pump 13 and the secondary pressurized diesel tank 21 to allow the diesel passing through the conduit 30 to enter the secondary pressurized diesel tank 21. There is a check valve 27 in the conduit 32 which prevents diesel from the secondary pressurized diesel tank 21 from passing to the fuel supply pump 13.

Pressurized diesel is passed from the secondary pressurized diesel tank 21 along the conduit 33 to the mixing chamber 28. The pressurized diesel flow along the conduit 33 is controlled by a diesel flow control valve 24. The diesel control valve 24 operates electrically by means of an electronic diesel controller 25 which in turn is operated by the electronic control unit 26. The electronic control unit 26 processes information about engine revolutions per minute from a draft angle sensor. The pressurized diesel passes through the diesel flow control valve 24 and enters the mixing chamber 28 at a pressure of approximately 689 kPa.

LPG is introduced into the tank 43 from a pump of a service station in which the tank 43 is filled at a pressure of approximately 1030 kPa in a liquid state. LPG is stored under pressure (1030 kPa) in a liquid state. Liquid LPG passes through conduit 34 through a shut-off valve 44, an in-line filter 45, a solenoid valve 48 and a check valve 49 to a LPG flow control valve 50. The LPG flow control valve 50 operates electrically by means of an electronic LPG controller 51 which is operated by means of the electronic control unit 26. The pressurized liquid LPG enters the mixing chamber 28 at approximately 689 kPa.

Both pressurized diesel and liquefied LPG enter the mixing chamber 28. The mixing chamber 28 is shown in both Figures 2 and 3. As an alternative to the electronic flow control valve system, 1/4 NPT Swage Lock 60 metering valves can be used and are preferably fixed to a ratio configuration default

The mixing chamber 28 is substantially spherical, the metering valves 60 being spatially diametrically opposed to each other. The mixing chamber 28 has an internal metal mesh 61 to facilitate the mixing of the fuels. The mixed fuel is discharged by means of the outlet 62 and the remaining mixed fuel is reintroduced by means of the input 63.

A preferred fuel ratio is 30% diesel and 70% LPG. However, there is a range of ratios from 10% diesel and 90% LPG to 90% diesel and 10% LPG. Fuel mix ratios can be achieved that use less than 30% diesel in which the lubricating power of the fuel mixture is increased. In particular, low sulfur diesel that is subjected to a treatment

Additional filtration has reduced lubricating power and fuel mixtures that have a diesel percentage of less than 30% require additional lubricating power to preserve engine components.

In addition to regulating diesel and LPG flow control valves 24, 50, in response to engine revolutions per minute, flow control valves 24, 50 are also regulated by accelerometer inputs that provide information about a up and down circulation on slopes. The entrances of

10 accelerometers are processed by electronic control unit 26.

The liquid fuel mixture is extracted from the mixing chamber 28 through a secondary fuel filtration unit 54 by means of the supply pump 15. The liquid fuel mixture is removed from the secondary fuel filtration unit 54 to the supply pump 15 and pumped to the common manifold 16 at a high pressure. The common manifold 16 distributes the liquid fuel mixture to the injectors 18 of each

15 combustion chamber (not shown). In Figure 1 only one injector 18 is shown by way of example. There is also a fuel pressure sensor 55 associated with the common manifold 16.

The mixture of excess fuel that has not been burned is returned from each injector 18 by means of a fuel temperature sensor 56. The excess fuel mixture associated with the common manifold 16 is returned by means of the pressure limiter 57. The excess fuel mixture is transported to the

20 overflow valve 58 by means of the pressure limiting valve 59 and the fuel cooler 64 to the pressurized tank 65 of mixed fuel. The pressurized tank 65 of mixed fuel has a purge valve 66 which allows the removal of air from the ducts and the fuel tank 65. From the pressurized tank 65 of mixed fuel, the fuel mixture is sucked into the mixing chamber 28 to return to the common manifold 16 and to the combustion chambers.

25 Emission test results

In order to provide support for the dual fuel system of the present invention, emissions tests were carried out by an independent third party, Brisbane City Hall, and the results were analyzed by Gilmore Engineers Pty Ltd. They were carried out two tests when the vehicle only used diesel and LPG / diesel (with a ratio of 70% LPG and 30% diesel). The diesel-only test (test 2969) was carried out on March 27, 2007 using the DT80 brief test. The LPG / diesel test (test 3262) was carried out on May 17, 2007 using the DT80 brief test. The same vehicle was used for both tests. The vehicle was an ISUZU truck (950 FVR) with a vehicle test mass of 13000 kg. The DT80 brief test is a series of accelerations and rapid decelerations interspersed with idle phases and is designed to assess vehicle emissions during operating modes and conditions typical of the “real world” stop and stop.

35 boot.

The results of the emission tests are summarized below:

UNITS

ONLY DIESEL (Test 2969) LPG / DIESEL (Test 3262) DNEPM limits

NOx (nitrous oxide)

g / kWh 6,211 0.380

g / km.t

0.707 0.686 1.5

PM LLSP (particulate matter)

mg / kWh 80,194 26,325

mg / km.t

9,126 2,831 fifty

Medium opacity

% 4,623 2,382 25

Based on these results, an engine under the circulation cycle of the DT80 short test using the LPG / diesel fuel mixture has a significantly lower opacity, significantly lower emissions of particulate matter and lower NOx emissions per km compared to diesel .

40 NOx emissions using the LPG / diesel mixture are only 45.7% of what is permissible by the DNEPM (National Environmental Protection Measure for Diesel Vehicle Emission). Particulate matter emissions are only 5.7% of what is permissible by the DNEPM limits and the average opacity is 9.5% of what is permissible by the DNEPM limits. In summary, the emission levels using the LPG / diesel mixture are substantially lower than what is allowed by the DNEPM limits.

Four. Five

Advantages

The preferred embodiment of the dual fuel system has the advantage that the LPG can be mixed with diesel with comparatively high ratios and can be used as a liquid fuel mixture in the combustion chamber. Unlike other dual fuel systems, the specifications of the

5 diesel engine manufacturer and manufacturer's guarantees are preserved. The advantage of the preferred embodiment arises from mixing liquid LPG and diesel to form a mixture of liquid fuel that can be distributed by means of the common manifold to the combustion chambers. Other dual fuel systems use LPG in a gaseous state, often introducing LPG with induction air.

The advantage of the dual fuel system of the preferred embodiment is that only slight changes are required in the

10 diesel engine, cleaner emission occurs and less frequent maintenance service is required, including oil changes. The dual fuel system of the preferred embodiment takes advantage of the relative economy and abundant supply of LPG compared to diesel and gasoline fuels. This relative economy can translate into savings in operating costs of vehicles with diesel engines.

Variations

Of course, it will be understood that although the foregoing has been presented by way of illustrative example of the present invention, all modifications and variations thereto such and others that do not depart from the scope of claim 1, as will be apparent to the Those skilled in the art are considered to be within the scope and wide scope of the present invention as defined herein.

In the entire description and claims of the report, it is not intended that the word "comprises" and

20 variations thereof, such as "comprise" and "comprising", exclude other additives, components, integers or stages.

Claims (12)

1. A set (10) of a dual fuel system to be installed with an internal combustion diesel engine that includes a fuel tank (43) for storing pressurized liquefied gas; a metering valve means (50) that can be operatively connected to the fuel tank (43) and is adapted to control the flow of the liquefied gas, in which the ratio between liquefied gas and diesel is predetermined; Y a mixing chamber (28) that can be operatively connected to the metering valve (50) and is adapted to mix a metered flow of the liquefied gas and a metered flow of diesel to form a liquid fuel mixture, in which during its use the assembly can provide the liquid fuel mixture to a combustion chamber of the diesel engine; characterized in that unburned excess fuel mixture is collected in an overflow tank (65) and returned to the mixing chamber (28) to be burned in the combustion chamber. 2. A set of a dual fuel system as claimed in claim 1, wherein the medium Dosing valve (50) includes a flow control valve (50) operatively controlled by an electronic control panel (51), said electronic control panel (51) controlling the flow control valve in response to processed information from the electronic control unit (26) of the vehicle.

3.

An assembly of a dual fuel system as claimed in claim 1 or 2, wherein the diesel fuel is pressurized before entering the mixing chamber and preferably the diesel fuel is pressurized by means of an in-line pump (20) and stored in a pressurized tank (21) before being used.

Four.

An assembly of a dual fuel system as claimed in claim 3, wherein the supply of pressurized diesel fuel to the mixing chamber (28) is regulated by means of a flow control valve (28) which is controlled operatively by means of an electronic control panel (25), the electronic control panel (25) being controlled by means of the electronic control unit (26) of the vehicle that receives and processes information to provide a relevant signal to the frame (26) electronic control.

5.

An assembly of a dual fuel system as claimed in any one of claims 1 to 4, wherein the liquefied gas is filtered before the metering valve with an in-line filter (45).

6.

An assembly of a dual fuel system as claimed in any one of claims 1 to 5, wherein the LPG tank (43), the metering valve means (50) and the mixing chamber (28) are connected by means of a gas conduit (34) with at least one valve (49) that can be closed between the LPG tank (43) and the metering valve (50).

7.

An assembly of a dual fuel system as claimed in any one of claims 1 to 6, wherein the reservoir (43) of liquefied gas stores LPG at a pressure of approximately 1030 kPa (150 psi) but greater than its pressure of steam of 550 kPa (80 psi).

8.

A set of a dual fuel system as claimed in any one of claims 1 to 7, wherein the ratio between LPG and diesel is a predetermined ratio that can vary between 50:50 and 90:10, respectively, and, preferably, it is about 70:30, respectively.

9.

An assembly of a dual fuel system as claimed in any one of claims 1 to 8, wherein the liquid fuel mixture is pumped to a common manifold (16) that can operate under elevated pressure, so that the mixture Liquid fuel remains in a liquid state, the common manifold (16) being connected to an injector (18) for each combustion chamber and the fuel mixture is distributed to each of the injectors (18) to be burned.

10.

An assembly of a dual fuel system as claimed in claim 9, wherein the fuel mixture is filtered before being distributed in the common manifold (16).

eleven.

An assembly of a dual fuel system as claimed in any one of claims 1 to 10, wherein the leftover fuel mixture is returned by means of a fuel temperature sensor (56) to a limiter (57) of the fuel pressure, then to an overflow valve (58) and a pressure limiting valve (59), then the excess fuel is passed through a fuel cooler (64) and kept under pressure in a pressurized tank (65) for a subsequent reintroduction into the mixing chamber (28).

12.

An assembly of a dual fuel system as claimed in claims 9 or 10, wherein there is a separate conduit from a diesel tank (11) to a supply pump (15) and subsequently to the common manifold (16) for that the engine can use diesel as the sole source of fuel.