NL2010861C2

NL2010861C2 - Liquefied petrol gas pump for displacing liquid lpg, housing for a pump chamber and fuel system comprising a lpg pump.

Info

Publication number: NL2010861C2
Application number: NL2010861A
Authority: NL
Inventors: Servatius Alfons Maria Jaasma
Original assignee: Vialle Alternative Fuel Systems Bv
Priority date: 2013-05-24
Filing date: 2013-05-24
Publication date: 2014-12-01

Description

Liquefied petrol gas pump for displacing liquid LPG, housing for a pump chamber and fuel system comprising a LPG pump

The invention concerns a liquefied petrol gas (LPG) pump for displacing liquid LPG. The invention further concerns a housing comprising a pump chamber lubricated by liquefied petrol gas. Further the invention relates to a fuel system comprising a liquid liquefied petrol gas pump.

Modern liquefied petrol gas fuel systems in cars run on liquid LPG. Liquid LPG is available from a storage, such as a tank in a car. The liquid LPG is stored at 8 - 10 atmospheres.

A LPG pump received in the tank of the car provides the liquid LPG from inside of the tank to the fuel system for e.g. subsequent direct or indirect injection. At room temperature LPG will evaporate if the pressure is reduced too much under 8 - 10 atmospheres. This prevents the use of normal pumps that actively 'suck' fuel towards the inlet of the pump chamber. By 'sucking' too hard, liquid LPG will evaporate.

A LPG pump that is to be arranged in a LPG storage is positioned in a fragile environment. The LPG storage (tank) is a pressure vessel. Only a small opening is provided through which the LPG pump is to be inserted. This results in dimensional constraints. Further the amount of heat in operating the pump, e.g. for driving a motor and/or created by friction, should be limited.

It is known to lubricate a LPG pump using liquid LPG. Lubrication using LPG is not optimal. During lubrication heat is created possibly resulting in (local) evaporation of the liquid LPG.

It is a goal of an aspect of the invention to provide an improved lubricated LPG pump. According to another aspect it is a goal to increase the pressurization in the LPG pump.

According to an aspect a liquefied petrol gas pump is provided comprising a housing, the housing having a first housing part comprising a pump chamber with a piston. The piston is guided in the housing, allowing a reciprocal movement of the piston, reducing and increasing the volume of the pump chamber. The pump chamber has an inlet and outlet for liquefied petrol gas. When the volume of the pump chamber is increased, the inlet opens and LPG enters the pump chamber. When the volume is reduced, LPG is discharged via the outlet. The liquid LPG is displaced and can be fed to fuel lines of a fuel system.

In an embodiment of the LPG pump the pump chamber and piston are arranged to be lubricate with the liquefied petrol gas. The LPG pump further comprises a membrane separating the first housing part from a second housing part arranged to be lubricated with a different lubricant. The other lubricant can be a more efficient lubricant than liquid LPG, such as an oily substance. Accordingly the piston is lubricated using the liquid LPG completely separate from other lubricated elements of the pump located in the second housing part. The membrane allows the transfer of a driving motion from the second housing part onto the piston received in the first housing part. The membrane is e.g. made from a flexible material. The driving motion is provided in the second part and is efficiently lubricated, while the piston of the pump chamber is lubricated by the liquid LPG.

In an embodiment the first housing part also comprises a leak chamber arranged to collect leaked liquefied petrol gas from the pump chamber over the piston. In an embodiment the leak chamber has an outlet from the housing. Lubrication of the piston is allowed by the LPG penetrating between the piston and piston guides. This results in leaking. The leaked LPG is collected in the leak chamber. The leak chamber is similarly separated from the other lubricant.

In an embodiment the membrane is a side wall of the leak chamber. In an embodiment the membrane is deformable. To transfer the driving motion onto the piston, the membrane deforms. The deformed membrane will also deform the shape of the leak chamber. The deformation of the leak chamber during a driving motion, such as a stroke, of the leak chamber results in a general constant volume of the leak chamber. The volume change is less than 10%. Accordingly the pressurization and motion of the liquid liquefied petrol gas present in the leak chamber is minimized.

The inlet/outlet opening of the leak chamber can have a predetermined size. If the opening is made smaller, the leak chamber can function as an additional pump chamber, secondary to the pump chamber. During a work stroke the leak chamber can be reduced in volume and as a result of the small outlet, choking the in/out flow of liquid to/from the leak chamber, the leak chamber is pressurized. The leak chamber pressure can be an additional pressure supporting the pressure in the pump chamber .

In an embodiment the first housing part also comprises a piston guiding body for guiding a reciprocal movement of the piston, the piston and piston guiding body arranged to be lubricated by the liquid liquefied petrol gas.

In an embodiment the inlet of the pump chamber comprises an inlet valve and the outlet of the pump chamber comprises an outlet valve. One or each of the inlet/outlet valves can be one-way valves. The one-way valves allow an opening and closing of the valves as a result of the piston action. In an embodiment the outlet valve is configurable to open at a predetermined pressure. This allows pressurizing the LPG in the pump chamber to a desired pressure and to supply the pressurized LPG to downstream applications connected to the housing outlet.

In other embodiments a pressure regulator is connected to the outlet, e.g. over fuel lines. The downstream pressure regulator is arranged to pressurize the supplied LPG. The downstream pressure regulator can be a predetermined pressure regulator having a predetermined orifice. In another embodiment the pressure regulator is configurable, regulated by an adjustable orifice of the pressure regulator.

In an embodiment the LPG pump connected to the pressure regulator is a continually variable yield LPG pump in combination with a pressure regulator having a predetermined orifice. By adjusting the yield of the LPG pump, e.g. by adjusting the drive speed (RPM), the resulting pressure downstream of the pressure regulator can be adjusted. A feedback loop (measuring the downstream pressure and adjusting the yield of the LPG pump accordingly) can be provided.

The pressure of the liquid in the pressure regulator/fuel lines connected downstream to the outlet of the pump chamber is present at the outlet valve. The outlet valve will open only if the pressure in the pump chamber is sufficient to overcome the pressure in the fuel lines connected to the outlet of the pump chamber.

In an embodiment the piston and piston guiding body allow a predetermined liquid LPG penetration. The predetermined penetration can be balanced such that significantly pressurizing the liquid LPG, e.g. by at least 10 atmospheres, results in a leak of about 20 - 35 %, while a low pressurization (0-2 atmospheres) results in a leak of at most 10%. A LPG pump providing at least 10 atmospheres of pressurization can operate at about 75 litres per hour, while the same LPG pump functioning as a displacement pump, pressurizing 0-2 atmospheres only, results in a 100 litres per hour discharge. This allows using one and the same drive for both pressurizing and displacement functions.

In an embodiment the piston is biased by a spring onto the membrane. This biases the membrane and piston to a default position, preferably a position of increased volume of the pump chamber. Further such an outward bias provides a counter force to a driving motion onto the piston, resulting in the piston and membrane moving to a default position.

In an embodiment the membrane and the piston are connected. Accordingly the assembled piece is compact.

In an embodiment the membrane is fixed to the housing along an edge, preferably a radial edge, of the membrane. In embodiment a central part of the membrane is arranged to move with respect to the housing.

In an embodiment the second housing part comprises a plunger receiving space. A plunger can be received in the plunger receiving space. The plunger can provide the driving motion of the piston. The plunger receiving space is arranged to be lubricated with a different lubricant, wherein the plunger receiving space is arranged to transfer movement of a plunger onto the membrane and piston. The plunger will drive the piston resulting in displacement of liguid LPG from the inlet to the outlet of the pump chamber.

The second housing part can comprise a plunger, wherein preferably the plunger is connected to an electromotor, preferably to an eccentric. The eccentric can drive the plunger. The plunger will move reciprocally. The transferred motion of the plunger onto the piston also results in a reciprocal movement. As the electromotor, plunger and eccentric are received in the second space a suitable, nonliquid LPG lubricant can be used for lubrication.

The liguefied petrol gas pump is preferably mounted in a LPG fuel storage. Preferably the LPG pump is mounted close to or onto the bottom of the LPG fuel storage / pressure vessel. This ensures that the inlet to the pump chamber is positioned in the liguid held in the pressure vessel. A buffer device can be provided around the LPG pump to collect a buffer quantity at and around the inlet of the pump.

According to a further aspect a housing for displacing liquid LPG is provided. The housing can be fixed to a drive, such as a plunger. The plunger provides a driving motion for displacing the liquid LPG. The housing can have a housing part comprising a pump chamber with a piston, the pump chamber having inlet and outlet for liquefied petrol gas, wherein the pump chamber and piston are arranged to be lubricate with the liquefied petrol gas, the housing further having a membrane arranged to transfer a driving motion onto the piston and the housing comprising a fixation device to fix the housing to a housing having a plunger receiving space. The housing is arranged as an attachment to a second housing comprising the drive for the driving motion of the piston in the housing. Suitable fixation devices can be provided to attach the housing the second housing of the drive. The membrane is suitable arranged to allow the transfer of the driving motion from the drive onto the piston. The housing is lubricated by liquid LPG, while the second housing to which the housing with pump chamber can be attached has a separate lubricating system, such as a system using oily substances.

According to yet a further aspect a fuel system and in an embodiment a bi-fuel system is provided. Liquid liquefied petrol gas can be supplied to a fuel system using a LPG pump according to any of the embodiments. The LPG pump is received in a liquefied petrol gas storage. The LPG pump's electromotor is connected by electrical wiring through an opening of the liquefied petrol gas storage to electrical terminals. The terminals can be connected to a power source, such as a car's battery. In the bi-fuel system a first fuel supply comprises the LPG fuel pump and a second fuel supply system comprising a liquid fuel storage and liquid fuel pump.

The fuel system can comprise a accessory plate or multivalve mounted on an opening of the liquefied petrol gas storage or tank.

The invention will now be explained in more detail below with reference to an illustrative embodiment shown in the drawings. In the drawings:

Figure 1 shows a cross sectional view of a LPG pump according to a first embodiment;

Figure 2 is a schematic partially exploded view of an assembly according to a first embodiment of the invention;

Figure 3 shows a LPG fuel system for liquid direct injection .

Figure 1 shows a cross sectional view of a LPG pump 10. The LPG pump 10 is arranged to pressurize LPG in liquid state. Liquefied LPG can be stored in liquid state at room temperature at a pressure of around 8-10 atmosphere.

In an embodiment the LPG pump 10 is a positive displacement pump arranged to take in and discharge a liquid flow of LPG from the stored liquefied LPG. In an embodiment the LPG pump 10 is arranged to pressurize the liquid LPG to at least 28, preferably at least 35 and more preferably at least 42 atmospheres.

The LPG pump 10 comprises a housing 12 and an auxiliary housing 14. Auxiliary housing 14 is fixed onto the housing 12, the fixation not shown in detail. Clearly different fixation devices can be used. A click-on arrangement is possible. In an embodiment housing 12 is detachable from auxiliary housing 14.

O-rings 18,20 are shown as sealing between the housing 12 and housing 14. Further membrane 1 is fitted between the two housings 12,14 in the illustrated embodiment.

In an embodiment the LPG pump 10 comprises a housing 12 and several auxiliary housings 14. In an embodiment two, three or more, such as five, auxiliary housings are connected to housing 12 .

Housing 14 has an inlet opening 16. The inlet opening 16 can be held in liquid LPG or can be connected to a filter held in liquid LPG. The liquid LPG is not shown in figure 1. Inlet 16 forms the suction side of the LPG pump 10.

In the shown embodiment an inlet valve 6, positioned directly downstream from the inlet opening 16, connects the inlet opening 16 to a pump chamber 5. Inlet valve 6 is arranged similar to one-way valve or check valve. The inlet valve 6 has a very low threshold for opening, allowing the liquid LPG to enter pump chamber 5 in auxiliary housing 14. A small negative pressure over the valve 6 results in opening of the valve 6.

In an embodiment the membrane 1 closes of at least one side of the pump chamber 5. Pump chamber 5 is received in auxiliary housing 14. The auxiliary housing 14 closes off several sides of the pump chamber 5.

An outlet valve 7 is positioned directly upstream from an outlet opening 22 in the pump housing 12. Pressurized liquid LPG can exit the pump chamber 5 via the outlet valve 7. In case of an embodiment as a positive displacement pump of LPG pump 10, outlet valve opens at a slight overpressure in pump chamber 5. Liquid LPG is sucked in at inlet end 16, collected in pump chamber 5 and discharge over outlet opening 22 .

A fuel line can be connected to the outlet opening 22. In an embodiment comprising several auxiliary housings 14, outlet opening 22 can be connected to a liquid LPG gallery, collected the discharged LPG from several pump chambers 5. The gallery can be connected to a downstream fuel line. In this embodiment the pressure of the LPG can be determined using another downstream positioned regulator. In an embodiment the downstream pressure regulator can comprise a return line.

In another embodiment a fuel line for pressurized liquid LPG can be connected to the outlet opening 22. Outlet valve 7 can be configured to open at a desired pressure. In an embodiment a pressure configurator (not shown) is connected to outlet valve 7 allowing to configuring the opening pressure of the valve. This allows setting the desired outlet pressure of the liquid LPG.

Inlet valve 6 is part of an inlet housing 26 fixed to auxiliary housing 14 sealed by O-ring 30. Outlet valve 7 is a part of an outlet housing 28 fixed to auxiliary housing 14 sealed by 0-ring 32. The housing 12, auxiliary housing 14 and inlet/outlet housings 26,28 can be manufactured efficiently and allow specialized production.

A piston 2 is arranged in the pump chamber 5 held by guides 3. Guides 3 allow the piston to move reciprocally 34 in the pump chamber 5, here from left to right and back. A spring 36 biases the piston 2 into a position to the left. Piston 2 moving to the right, against the bias of spring 36, will result in a reduction of the volume of pump chamber 5, pressurizing the liquid LPG present in the pump chamber 5 and allowing the pressure to rise above the threshold pressure of the outlet valve 7. If the pressure rises above the threshold pressure, the outlet valve 8 will open, allowing the pressurized liquid LPG to exit the pump housing 12.

The return stroke of the piston 2 as a result of the bias provided by the spring 36 will enlarge the volume of the pressure chamber 2. Outlet valve 7 will close. The volume increase results in a negative pressure over inlet valve 6, which will open, allowing fresh liquid LPG to enter the pump chamber 2. The pump chamber is not fully emptied during a pressurizing stroke.

During the pressurizing stroke liquid LPG can leak / penetrate between the piston 2 and guiding walls 3 resulting in lubrication. Leaked LPG will reach leak chamber 40 connected to a further outlet opening 9. Leaked LPG is collected in the leak chamber 40 and can be discharged over outlet opening 9.

In the embodiment wherein the LPG pump 10 is mounted inside a LPG storage, further outlet opening 9 can be an open connection with that LPG storage, allowing the leaked liquid LPG to return to the LPG storage. The leak chamber 40 is surrounded by piston 2, housings 12,14 and membrane 1.

In order to make the driving stroke, a plunger 8 is provided. The plunger 8 is received in a plunger receiving space 4. Plunger 8 can be connected to a electromotor having an eccentric (not shown). Driving the electromotor and eccentric results in plunger 8 moving reciprocally left-right 34. As a result of the bias provided by spring 36, piston 2 is held onto the plunger 8. The electromotor can be arranged inside the LPG pump housing 12. Piston 2 can be held between guiding walls 44.

The plunger receiving space 4 is a part inside the pump housing 12. In an embodiment the electromotor having the eccentric is received in the LPG pump 10.

In an embodiment the auxiliary housing 14 is provided as well as a fixation for fixing the auxiliary housing 14 onto a housing having the plunger receiving space 4. The auxiliary housing 14, including the pump chamber 5, piston 2, membrane 1, inlet and outlet valves 6,7, can be fixed to the housing 12 .

In the plunger receiving space 4 heat can be created as a result of friction forces. In the shown embodiment the plunger receiving space, especially guiding walls 44, can be lubricated using oils.

According to the invention a membrane 1 is provided between the plunger receiving space 4 and pump chamber. The membrane still allows the plunger to cooperate with the piston 2. The reciprocal movement of the plunger 4 will move not only the piston 2 but also part of the membrane 1.

The membrane 1 is provided such that the oils and lubricants used for lubricating the plunger 8 and guiding walls 44 are separated from the liquid LPG present in the pump chamber and the leak chamber 40. The heat created by plunger 8 is contained and held at a distance from the liquid LPG, reducing the available heat for evaporation of the liquid LPG.

In the illustrated embodiment an aluminum body 50 is fixed by a bolt 52 to piston 2. The membrane 1 is fixed between the body 50 and piston 2. The connection is leak free.

Membrane 1 can flexible deform during the reciprocal stroke movement. A circumferential or radial part 60 of membrane 1 is fixed, while a central part of the membrane can move with respect to the housing to transfer a movement of the plunger 4 onto piston 2.

The illustrated LPG pump 10 is assembled by providing auxiliary housing 14, positioning spring 36 and piston 2 around housing part 46 and mounting inlet and outlet housings 26,28 and fixing the auxiliary housing 14 onto housing 12 while clamping the membrane 1 in between the two housings. The radial part of the membrane 1 is clamped between the two housings 12,14. Several kinds of fixations are available to achieve a leakage free fixation of the membrane. In an embodiment auxiliary 0-rings can be used for sealing the membrane .

The piston 2 and guides 3 are engineered having a predetermined tolerance. The tolerance can allow for a recurring leakage flow of liquid LPG between the piston 2 and guides 3 toward the leakage chamber 40. At an outlet pressure of about 25 bars or more the LPG pump 10 can deliver 70 liters per hour, while at lower outlet pressure (9 - 12 bars) about 120 liters/hour is delivered. The constant leaking allows a single LPG pump 10 according to the design as shown in Figure 1 to be used at several pressures without having to adjust the power of the electromotor.

In another embodiment the membrane 1 is fixed leak free to the auxiliary housing 14.

In the illustrated embodiment the leak chamber 40 and pump chamber 6 comprise liquid LPG as lubricant, whereas plunger 8 is lubricated using oils. The membrane 1 separates two housing parts, each housing part having a different lubricant. The piston 2 is lubricated by liquid liquefied petrol gas, whereas the plunger 8 is lubricated with a different lubricant, such as an oily substance.

Figure 2 is a schematic view of a fuel tank assembly 101 suitable for supplying liquefied petrol gas in a liquid state to a fuel system of an engine. The assembly 101 is shown in an cross sectional exploded view. The assembly comprises the LPG tank 110 having an opening 111 and a multivalve or accessory plate 130.

The LPG fuel tank 110 arranged as pressure vessel is shown in cross section. The LPG tank 110 is torodially shaped. The LPG tank 110 can be fitted in a car and replace the spare wheel. In this embodiment the LPG tank can comprise two shell like halves that are welded together. The LPG tank is provided with an opening 111. The opening 111 in this embodiment comprises a hole in the wall of the tank 110 into which a cylindrical part 112 is welded. The cylindrical part 112 can be provided with a flanged edge 113 onto which a multivalve or accessory plate 130 can be mounted. The flanged edge 113 can extend inwardly from the cylindrical wall 112. In other embodiments the flanged edge can extend outwardly. The cylindrical part 112 and flanged edge 113 are examples of embodiments for an opening 111 of the LPG tank 110.

The opening is typically about 48 mm in diameter. The invention is not limited to 48 mm openings. The accessory plate is typically a 48 mm opening suitable accessory plate. The invention is however not limited to such conventional accessory plates.

Fuel level 116 shows the tank 110 filled to about maximum capacity. Other embodiments are also possible.

Figure 1 schematically shows the multivalve 130 according to an embodiment. The multivalve 130 has a bottom surface 121 that is arranged to be fitted onto the opening 111, specifically onto the flanged edge 113. A flange 122 extends angularly and is arranged to be positioned in contact with flange 113 of the opening 111. Surface 121 and flange 122 can cooperate with the opening such that an airtight fitting of the adaptor 120 on the opening 111 can be achieved.

Flange 122 is not necessary. Clearly many embodiments are possible to achieve such fitting and the invention is not limited to the illustrated embodiment.

Generally the body 131 of the multivalve 130 is generally disc shaped. A conventional accessory plate 130 shown in figure 1 comprises a disc shaped body 131 having a fuel-in 132 and fuel-out 133 channels. Further the accessory plate 130 can comprise at least one safety feature 134, such as a pressure relief valve and/or a pressure relief device (thermofuse). Further the illustrated accessory plate 30 comprises a floater 136 connected via an arm 137 hingeably connected to a schematically illustrated sensor 138. Sensor 138 can convert the hinging movement of the floater 136, resulting from the increase (during filling) or lowering (during use) of the fuel level 116 of fuel inside the LPG tank 110. The sensor 138 can be connected (not shown) to a controller or to an indicator on the dashboard of the car. The floater 136 is, when the tank 110 and accessory plate 130 is assembled, arranged inside the tank.

The functionality of the accessory plate 130 is adapted to a liquid LPG injection fuel system, such as an LPi or LDPi system. Multivalve 130 has a return flow channel 126. In a liquid LPG injection fuel system generally a fuel return line can be arranged to return LPG to the fuel tank. Examples of such fuel systems comprising a return line are disclosed in EP 2 260 200 and EP 1 785 618, the complete content of which is included by reference. The fuel return channel 126 can be connected to the return line, e.g. coming from the high pressure pump in a direct injection fuel system.

The fuel return channel 126 can be a bored channel in body 131 and can further comprise a tubular fuel line 158 connected to the bore extending into the LPG tank 110.

On a side surface 128 of body 131, a tube connector 150 can be mounted for connecting the channel 126 to a return fuel line. The tube connector 150 can comprise a pressure sensor 129 arranged to measure the pressure in the return fuel line / channel. The measured pressure can be forwarded to a fuel controller (ECU) providing feedback control.

As a further member providing liquid LPG injection functionality, an arm 151 extends from the multivalve 130. The arm 151 extends into the tank 110, when the multivalve 130 is mounted on the opening 111. The arm 151 is arranged to position the LPG pump 160 in the LPG tank 110. The LPG pump 160 can be fixed to the arm 151, directly or indirectly. A buffer storage, formed by a plastic bag 161, can surround the entrance of the LPG pump 160.

The LPG pump 160 can be the LPG pump 10 according to figure 1 comprising several pump chamber, connected over a gallery to a pressure regulator. The LPG pump 160 can comprise an electromotor having plunger 8.

The arm 151 can also be connected directly or indirectly with the buffer storage, the buffer storage holding the LPG pump 160. The arm 151 is arranged to position the fuel pump 160 and/or the buffer storage close to the bottom of the LPG tank 110. This ensures that the LPG pump 110 is provided with as much fuel as possible, even when the tank 110 is close to empty.

Further the arm 151 results in a fixed connection, preferably a mounting connection, between the multivalve 130 and fuel pump 60. This fixed relationship allows arranging the multivalve 130 and fuel pump 160 on and into the LPG tank 110 in a single operation, reducing complexity during assembly.

The buffer storage is arranged to take in fuel and provide a buffer of fuel to the entry port of the fuel pump 160.

Although figure 2 illustrates a schematically representation of the buffer storage, it will be clear to the skilled man that many embodiments are possible.

LPG pump 160 is connected, via a fuel line 162 to the fuel out channel 133 of the accessory plate 130. This allows the LPG from the tank 110 to be supplied to the engine.

Yet a further member providing liquid LPG injection functionality is formed by electrical connectors 165. These can be connected to a battery 167, shown schematically, of the car. The connectors 165 can be connected to electrical wiring 166. The electrical wiring 166 extends into the internal space of the LPG tank 110. The electrical wiring 166 can be connected to the LPG pump 160 for providing energy for the pump 160 to operate.

For achieving a leak free connection when mounting multivalve 130 on opening 110, the skilled person will have different options available. Suitable seals, rubbers, can be used to obtain a leak free connection.

Figure 3 shows schematically a fuel system for a liquid LPG injection fuel system having direct injection. In this embodiment a single fuel liquid LPG injection system is illustrated. Clearly the liquid LPG injection fuel system can be part of a bi-fuel system, wherein the user can switch between a liquid fuel, such as petrol or diesel, and a liquefied vapour, such as LPG.

In an embodiment the fuel system can be an injection fuel system (LPi). The invention is not limited to direct injection fuel systems.

Liquefied petroleum gas can be supplied to LPG tank 200 using the fuel-in 201. This can be done at a gas station. The LPG from the LPG tank can be collected and buffered in storage buffer 202 around the entry of the LPG fuel pump 203 received and positioned inside the LPG tank near the bottom thereof.

The LPG pump 203 can provide the liquid LPG to a high pressure pump 205 using a suitable fuel tube 206. High pressure pump 206 can raise the pressure of the liquid LPG up to e.g. 30 atm or higher. A LPG return flow 207, in this embodiment from the high pressure pump 205, is returned to the LPG tank 200. A pressure sensor 209 can measure the pressure of the returned fuel. All LPG is transported through schematically illustrated opening 208 of the LPG tank 200. From the high pressure pump 205 a suitable high pressure line transports the fuel to the high pressure fuel rail (not shown) such that the fuel is injected in a (one of four illustrated) cylinder of the engine 210. The LPG pump 203 and high pressure pump 205 can be controlled by a suitable fuel controller, such as an ECU 211. Suitable electrical wiring connects the ECU with the elements. The ECU can receive measured values or representative values for the pressure from pressure sensor 209.

An indirect injection (bi-)fuel system would also be possible to be equipped with a LPG pump according to the invention .

From the above it will be clear that many embodiments are possible. The invention is not limited to the shown embodiments. In an embodiment the adaptor is an auxiliary piece that can be fitted through the fuel in of the common accessory plate. This adaptor is fitted on the outside of the accessory plate having some members providing liquid LPG injection functionality extending into the LPG tank.

CLAUSES

1. Liquefied petrol gas pump for displacing liquid LPG comprising a housing, the housing having a first housing part comprising a pump chamber with a piston, the pump chamber having inlet and outlet for liquefied petrol gas, wherein the pump chamber and piston are arranged to be lubricated with the liquefied petrol gas, the liquefied petrol gas pump further having a membrane separating the first housing part from a second housing part arranged to be lubricated with a different lubricant, such as an oily substance, wherein the membrane is arranged to transfer a driving motion from the second housing part onto the piston.

2. Liquefied petrol gas pump according to clause 1 , wherein the first housing part also comprises a leak chamber arranged to collect leaked liquefied petrol gas from the pump chamber over the piston, the leak chamber preferably having an outlet from the housing.

3. Liquefied petrol gas pump according to clause 2, wherein the membrane is deformable and forms at least a side wall of the leak chamber.

4. Liquefied petrol gas pump according to any of the preceding clauses, wherein the first housing part also comprises a piston guiding body for guiding a reciprocal movement of the piston, the piston and piston guiding body arranged to be lubricated by the liquid liquefied petrol gas.

5. Liquefied petrol gas pump according to clause 2 and 4, wherein the pump chamber is connected with the leak chamber over the piston and piston guiding body, and wherein the piston and piston guiding body are arranged to be penetrated by the liquid liquefied petrol gas.

6. Liquefied petrol gas pump according to any of the preceding clauses, wherein the inlet of the pump chamber comprises a inlet valve and the outlet of the pump chamber comprises an outlet valve, wherein preferably the inlet and outlet valves are one-way valves and wherein more preferably the outlet valve is configurable to open at a predetermined pressure .

7. Liquefied petrol gas pump according to any of the preceding clauses, wherein the piston is biased by a spring onto the membrane.

8. Liquefied petrol gas pump according to any of the preceding clauses, wherein membrane and the piston are connected.

9. Liquefied petrol gas pump according to any of the preceding clauses , wherein the membrane is fixed to the housing along an edge, preferably a radial edge, and wherein a central part of the membrane is arranged to move with respect to the housing.

10. Liquefied petrol gas pump according to any of the preceding clauses, wherein the second housing part comprises a plunger receiving space adapted to receive a plunger, wherein the plunger receiving space is arranged to be lubricated with the different lubricant, wherein the plunger receiving space is arranged to transfer movement of a plunger onto the membrane and piston and the piston is arranged to be driven by the plunger.

11. Liquefied petrol gas pump according to clause 10, wherein the second housing part comprise a plunger, wherein preferably the plunger is connected to an electromotor .

12. Liquefied petrol gas pump according to clause 11, wherein the liquefied petrol gas pump is to be mounted in a LPG fuel storage.

13. A housing for displacing liquid LPG the housing having a housing part comprising a pump chamber with a piston, the pump chamber having inlet and outlet for liquefied petrol gas, wherein the pump chamber and piston are arranged to be lubricate with the liquefied petrol gas, the housing further having a membrane arranged to transfer a driving motion onto the piston and the housing comprising a fixation device to fix the housing to a housing having a plunger receiving space.

14. Fuel system for liquefied petrol gas in liquid state comprising a liquefied petrol gas pump according to clause 11 or 12 received in a liquefied petrol gas storage, wherein the electromotor is connected by electrical wiring through an opening of the liquefied petrol gas storage to electrical terminals.

15. Bi-fuel system comprising as a first fuel supply a fuel system according to clause 14 and further comprising a second fuel supply system comprising a liquid fuel storage and liquid fuel pump.

Claims

A liquefied petroleum gas (LPG) pump for pumping liquid LPG comprising a housing, the housing comprising a first housing part provided with a pumping chamber and a piston, the pumping chamber having an entrance and exit for liquefied petroleum gas, the pumping chamber and piston are adapted to be lubricated with the liquefied petroleum gas, the liquefied petroleum gas pump further having a membrane separating the first housing part from a second housing part adapted to be lubricated with another lubricant, such as an oily substance, the membrane is arranged to transmit a driving movement from the second housing part to the piston, the first housing part also comprising a piston-conducting body for guiding a reciprocal movement of the piston, the piston and the piston-conducting body being adapted to to be lubricated with the liquid LPG.

2. LPG pump according to claim 1, wherein the first housing part also comprises a leak chamber adapted to collect LPG leaked from the pump chamber via the piston, the leak chamber preferably having an exit from the first housing part

The LPG pump according to claim 2, wherein the membrane is deformable and forms at least one side wall of the leakage chamber.

The LPG pump according to claim 2, wherein the pump chamber is connected to the leak chamber via the piston and the piston-conducting body, and wherein the piston and the piston-conducting body are adapted to allow creeping of the liquid LPG therebetween.

5. LPG pump according to one of the preceding claims, wherein the entrance to the pumping chamber comprises an input valve and the output of the pumping chamber comprises an output valve, wherein preferably the input and output valves are non-return valves and wherein the output valve is preferably adapted to open a predetermined pressure.

6. LPG pump according to one of the preceding claims, wherein the piston is prestressed by means of a spring towards the diaphragm.

7. LPG pump according to one of the preceding claims, wherein the membrane and the piston are connected to each other.

8. LPG pump according to one of the preceding claims, wherein the membrane is fixedly connected to the housing along an edge, preferably a radial edge, of the membrane, and wherein a central part of the membrane is adapted to move relative to the House.

9. LPG pump according to one of the preceding claims, wherein the second housing part comprises a receiving space for a ram, wherein the receiving space for the ram is adapted to be lubricated with the other lubricant, the receiving space for the ram being adapted to move movement of transferring a ram to the diaphragm and piston, and wherein the piston is adapted to be driven with the ram.

The LPG pump according to claim 9, wherein the second housing part comprises a ram, the ram preferably being connected to an electric motor.

The LPG pump according to claim 10, wherein the LPG pump can be included in an LPG fuel tank.

12. A housing for pumping liquid LPG, wherein the housing has a housing part comprising a pump chamber with a piston, the pump chamber having an entrance and exit for liquid LPG, the pump chamber and piston being arranged to be lubricated with the liquid LPG, wherein the housing further has a diaphragm adapted to transmit a driving movement to the piston, and the housing comprises a coupling device for coupling the housing to a housing having a ram receiving space, the first housing part also a piston-conducting body for guiding a reciprocal movement of the piston, the piston and the piston-conducting body being adapted to be lubricated with the liquid LPG.

A liquid-state LPG fuel system comprising an LPG pump according to claim 10 or 11 included in an LPG fuel tank, wherein the electric motor is coupled to electrical connection points via electrical connections running through an opening of the LPG fuel tank.

A dual fuel system comprising as a first fuel supply unit a fuel system according to claim 13 and further comprising as a second fuel supply unit a liquid fuel tank, such as for gasoline or diesel, and a fuel pump for liquid fuel.