DE112014001098B4 - Fuel system for an internal combustion engine and method for handling water in fuel in a fuel system - Google Patents

Abstract

Fuel system (4) for an internal combustion engine (2), the fuel system of which comprises a first fuel tank (20), a second fuel tank (22), a first fuel line (36) arranged in connection with the first fuel tank (20) and the second fuel tank (22). a second fuel line (40) disposed in communication with the first fuel tank (40), a main feed pump (26), and a transfer pump (28), the main feed pump (26) for pumping fuel from the first fuel tank (20) through the second one Fuel line (40) is arranged, and wherein the transfer pump (28) for pumping fuel from the second fuel tank (22) to the first fuel tank (20) via the first fuel line (36) is arranged, characterized in that a Wasserabscheide pre-filter (30 ) is arranged downstream of the transfer pump (28), so that the transfer pump (28) pumps pressurized fuel through the pre-filter (30), and that a water is arranged in connection with the first fuel tank (20), so that the water tank (54) is connected to the pre-filter (30) and receives separated water from the pre-filter (30).

Description

Background of the invention and prior art

The present invention relates to a fuel system and a method according to the preambles of the appended independent claims. The invention also relates to an internal combustion engine and a vehicle having such a fuel system.

An internal combustion engine such as a diesel engine or a gasoline engine is equipped with a fuel system for pumping fuel from one or more fuel tanks for injection of the internal combustion engine. The fuel system includes one or more fuel pumps that may be mechanically driven by the engine or by an electric motor. The fuel pumps generate a fuel flow and a pressure for pumping the fuel for the injection of the internal combustion engine, which supplies fuel to the combustion chamber of the internal combustion engine.

The fuel system also includes a fuel filter for filtering the fuel before it reaches the injection of the internal combustion engine. The internal combustion engine and its injection are sensitive to contamination and may be severely affected if the fuel is too contaminated. Impurities can include solids, gases or liquids. Even if the fuel contains only a small amount of impurities, the result may be that the internal combustion engine is not driven by the fuel. Therefore, fuel systems include a fuel filter that filters particulates and separates water in the fuel. Water separated from the fuel is trapped in prior art fuel systems in a cavity in the fuel filter. This cavity absorbs only a small amount of water and therefore fills up rapidly during operation of the internal combustion engine. If the water is not emptied from the cavity, the fuel filter fails, that is, the fuel that reaches the engine may be contaminated, which may thus affect the engine and the injection. At high humidity or engine operation with fuel containing a lot of water, this problem often occurs. Passing the separated water into a separate water tank, which holds a larger volume of water than the cavity of the fuel filter, would reduce the risk of fuel filter failure due to too full a cavity during operation. In this way, the risk of damage to the engine and injection would be reduced.

According to the prior art, separated water is collected in a water tank which receives a larger volume than the cavity of the water separation fuel filter.

The patent EP 2 285 615 B1 describes a fuel system for an internal combustion engine comprising a water tank disposed within a fuel tank. The fuel system also includes a water trap suction filter located upstream of a fuel pump. Downstream of the fuel pump, a pressure filter is arranged, which also separates water in the fuel. The separated water from both filters is directed via a line to the water tank inside the fuel tank. By placing the water tank inside the fuel tank, the problem of freezing the water tank at low temperatures is eliminated, and at the same time a larger volume of water can be collected before the water tank needs to be emptied.

According to the prior art, separated water can also be trapped in the fuel tank, which accommodates a larger volume than the cavity of the water separation fuel filter.

The patent EP 2 078 845 A1 describes a device that prevents fuel containing water from reaching an internal combustion engine. The fuel system includes a fuel filter located downstream of a fuel delivery pump. The fuel filter separates water in the fuel and the water is then returned to the fuel tank. Since water has a higher density than fuel, the separated water sinks to the bottom of the fuel tank and thus can be emptied by opening a plug at the bottom of the fuel tank. In this way, a larger volume of water can be collected and the risk of damage to the engine and injection is reduced.

Despite the prior art solutions in this field, there is a need to develop a fuel system which reduces the risk of damage to the injection and internal combustion engine and reduces the risk of service interruptions due to impurities in the fuel.

The document DE 12 64 147 A discloses a fuel cleaning device in which fuel is passed via a filter and the water separated therefrom via a return line to a space which is separated from a main fuel supply by means of a second filter.

The document DE 10 2010 043 644 A1 discloses a fuel supply system including a fuel tank having a first tank portion and a second tank portion formed as a buffer reservoir. The tank areas are connected by means of a fuel pump and a water-separating filter.

The document DE 37 01 259 A1 discloses a device for removing water from the fuel line system of an internal combustion engine, comprising a pump device that automatically turns on in response to a present in a water tank water level.

The document DE 24 36 080 A1 discloses a separator for fluids of various densities.

Summary of the invention

The object of the present invention is to provide a fuel system for an internal combustion engine, which reduces the risk of damage to injection and internal combustion engine and reduces the risk of interruption of operations by impurities in the fuel.

Another object of the invention is to provide a fuel system for an internal combustion engine, which enables easier handling of separated water as in the prior art.

Another object is to provide a fuel system that is simple and space efficient.

These objects are met by a fuel system of the type described initially, which has the features mentioned in the characterizing part of patent claim 1.

These objects are also met by an internal combustion engine with a fuel system according to the characterizing part of claim 11. Similar objects are also met by a method for controlling a fuel system according to the characterizing part of claim 13. Similar objects are also met by an internal combustion engine and a vehicle having such a fuel system.

By disposing a prefilter downstream of a transfer pump in a low-pressure circuit in a fuel system for an internal combustion engine, a fuel system is provided which reduces the risk of service interruptions due to impurities in the fuel. The transfer pump, whose main task is to supply fuel to the first fuel tank, pumps fuel from the second fuel tank through the pre-filter. The pre-filter filters out particles and eliminates water in the fuel. The filtered fuel is then supplied to the first fuel line to the first fuel tank. The fuel that reaches the main pump is thus pre-filtered and the main pump is thus protected from contamination in the fuel. The separated water is directed to a water tank arranged in communication with the first fuel tank. The water tank takes up a larger volume than the volume taken up by prior art water separation fuel filters, and thus the water tank does not run the risk of being replenished in a short time. The risk that the pre-filter will fail is therefore reduced and thus the risk of introducing contaminated fuel and water to the injection and internal combustion engine is also reduced. In this way the risk of business interruption due to contamination is reduced.

Conveniently, a first electric motor for driving the transfer pump is arranged and a second electric motor for driving the main delivery pump is arranged. Further, the transfer pump and the main delivery pump are suitably low pressure pumps.

Preferably, the pre-filter is a fine-meshed water separator fuel filter. Such a water separation prefilter suitably comprises a filter housing and a filter element, wherein an inlet of the filter housing is connected to the transfer pump, a first outlet is connected to the first fuel line and a second outlet is connected to the water tank.

Conveniently, the water tank is disposed in communication with the bottom of the first fuel tank so that a partition wall keeps the water in the water tank and the fuel in the first fuel tank separated. The partition may alternatively consist of the bottom wall of the fuel tank. When the water tank is full, it is suitably emptied through a spout in the bottom wall of the water tank. Since water and fuel are separated by a dividing wall, there is no danger of fuel being accidentally emptied when the water is drained. In this way, a fuel system for an internal combustion engine is provided, which allows a simpler handling of separated water as in the prior art.

Suitably, an electric heater is arranged in connection with the water tank. In this way, a fuel system for an internal combustion engine is provided which reduces the risk reduces the collected separated water from freezing at low temperatures. Alternatively, the water tank may be formed so as not to allow freezing. When the engine is started, the fuel flowing back to the first fuel tank is heated. The fuel in the first fuel tank is thereby heated, and since the water tank is disposed in communication with the first fuel tank, the water trapped in the water tank can be heated by the conductivity of the fuel tank.

Suitably, a drain valve is arranged at the outlet of the water tank, which is connected via a CAN bus to a control device. Alternatively, a level sensor connected to the CAN bus is arranged inside the water tank, so that the driver is warned with a light and / or audio signal when the water in the water tank has reached a certain predetermined level in the water tank. In this way, a fuel system for an internal combustion engine is provided, which allows a simpler handling of separated water as in the prior art.

By placing the water tank in communication with the bottom of the first fuel tank, a smaller area is occupied in a limited-space chassis and a space-saving fuel system is provided. Furthermore, this arrangement of the water tank means that it is more accessible and visible.

Suitably, the water container comprises a transparent material that allows the driver to easily recognize when the water container is full and needs to be emptied. In this way, a fuel system for an internal combustion engine is provided, which allows a simpler handling of separated water as in the prior art.

Suitably, the first fuel tank is configured to receive a smaller volume than the second fuel tank. Preferably, the first fuel tank takes up 20 to 50 liters and the second fuel tank 300 to 1,000 liters. Suitably, the water tank takes up 1 to 10 liters. In this way, the limited space chassis is advantageously utilized and a space efficient fuel system is provided.

Suitably, a valve is located downstream of the transfer pump and downstream of the prefilter. The valve has an inlet connected to the transfer pump, a first outlet connected to the first fuel line and a second outlet connected to the second fuel line, so that the transfer pump is connected to the first fuel line when the valve is arranged in a first position, and the transfer pump is arranged with the second fuel line when the valve is arranged in a second position. In this way, the first fuel tank can be bypassed and the transfer pump can pump fuel from the second fuel tank to the second fuel line, downstream of the first fuel tank and main delivery pump, and on to the engine.

Suitably, the main delivery pump, transfer pump and valve are connected to the controller via the CAN bus. Thus, a compact fuel system is provided which is easy to control and thus provides for proper fueling of the internal combustion engine.

By disposing the main pump in the first fuel tank, the main pump is protected from the environment and natural cooling of the fuel in the first fuel tank is achieved. Alternatively, the transfer pump, pre-filter and valve are also disposed within the first fuel tank. With the arrangement of the main pump, the transfer pump, the pre-filter and valve within the first fuel tank, a space-saving fuel system is achieved.

Other characterizing features and advantages of the invention are set forth in the following detailed description.

Brief description of the drawings

The following is an exemplary description of a preferred embodiment of the invention with reference to the accompanying drawings.

1 shows a schematic side view of a vehicle, which includes a fuel system for an internal combustion engine according to the present invention.

2 shows a coupling diagram for a fuel system according to the present invention.

3 shows a flow diagram of a method for handling water in fuel in a fuel system according to the present invention.

Detailed description of an embodiment according to the invention

1 shows a schematic side view of a vehicle 1 that a fuel system 4 for an internal combustion engine 2 includes. The internal combustion engine 2 is with a gearbox 6 connected, in turn, via a transmission with the drive wheels 8th of the vehicle 1 connected is. The vehicle also includes a chassis 10 ,

2 shows a coupling diagram for the fuel system 4 , The fuel system 4 includes several components, one of which is a main fuel filter 12 , a high pressure pump 14 , a memory in the form of a so-called common rail system 16 and a schematically illustrated injection 18 in the form of a fuel injector in the internal combustion engine 2 are arranged. Alternatively, the common rail system 16 be replaced by another form of injection, for example, a piezo or block injection. The fuel system 4 also includes a first fuel tank 20 , a second fuel tank 22 , a third fuel tank 24 , a main pump 26 , a transfer pump 28 , a pre-filter 30 and a valve 32 , These components may be on the chassis 10 be arranged of the vehicle. The main fuel filter 12 is downstream of the main feed pump 26 and upstream of the high pressure pump 14 in the fuel system 4 arranged. Furthermore, the fuel system includes 4 a return line 13 , through the excess fuel of injection 18 , Common rail system 16 , High pressure pump 14 and main fuel filter 12 back to the first fuel tank 20 flows.

All three tanks 20 . 22 . 24 are each at their upper parts with a vent pipe 50 connected, via an air filter 51 connected with the environment. The vent pipe 50 Make sure the pressure in the respective tanks 20 . 22 . 24 regardless of how much fuel is in each tank. The air filter 51 Prevents impurities in the ambient air in the vent pipe 50 when venting the tanks penetrate.

The first fuel tank 20 is designed to take up a smaller volume than the second fuel tank 22 and the third fuel tank 24 , The second fuel tank 22 and the third fuel tank 24 They occupy substantially the same volume and have a self-regulating flow between them between the lower part of the second fuel tank 22 and the third fuel tank 24 arranged connecting pipe 34 on. The transfer pump 28 is according to 2 between the first fuel tank 20 and the second fuel tank 22 arranged. The transfer pump 28 is driven by a first electric motor M1 and serves mainly to fuel from the second fuel tank 22 to the first fuel tank 20 via a first fuel line 36 to pump. Between the first fuel tank 20 and the second fuel tank 22 is an extra line 38 arranged so that fuel from the first fuel tank 20 to the second fuel tank 22 can flow when the first fuel tank 20 gets too full. The main pump 26 is inside the first fuel tank 20 is thus protected from the environment and is cooled by the fuel. The main pump 26 is driven by a second electric motor M2 and pumps the fuel from the first fuel tank 20 via a second fuel line 40 through the main fuel filter 12 to the high pressure pump 14 , The fuel then becomes a common rail system under high pressure 16 and on to the injection 18 pumped. The main pump 26 and the transfer pump 28 be from a control device 42 via a CAN bus 44 controlled.

The pre-filter 30 , which is downstream of the transfer pump 28 is arranged, is preferably a fine-meshed water separator fuel filter. In the second fuel tank 22 is upstream of the transfer pump 28 a coarse-meshed sieve 52 arranged through which the transfer pump 28 Sucking up fuel. The coarse-meshed sieve 52 filters out particles over a certain specified size. The transfer pump 28 sucks fuel from the second fuel tank 22 , pressurizes the fuel and then pumps it through the pre-filter 30 , The fuel then becomes the first fuel line 36 to the first fuel tank 20 fed. The water in the pre-filter 30 is separated from the pre-filter 30 to a water tank 54 passed in conjunction with the bottom of the first fuel tank 20 is arranged. The water tank 54 takes up a larger volume than that of the water separator fuel filter 30 recorded volume and the water tank 54 thus does not run the risk of being replenished in a short time. The danger that the pre-filter 30 is therefore reduced, and thus also the risk of supplying contaminated fuel with water to injection 18 and internal combustion engine 2 reduced.

The bottom wall of the water tank 54 has a spout, in conjunction with which a drain valve 56 is arranged. The drain valve 56 is via the CAN bus 44 with the control device 42 connected. The water tank 54 is transparent, meaning the driver can easily recognize when the water tank 54 becomes full, and thus can determine when the water tank 54 must be emptied before or after driving. The emptying is done manually via the drain valve 56 when the vehicle is at a designated emptying location. According to another embodiment, one with the CAN bus 44 connected level sensor within the water tank 54 be arranged so that the driver is warned with a light and / or audio signal when the water in the water tank 54 a certain predetermined level in the water tank 54 has reached.

The valve 32 is downstream of the pre-filter 30 arranged and includes one with the transfer pump 28 connected inlet, one with the first fuel line 36 connected first outlet and one with the second fuel line 40 connected second outlet. The valve 32 is with the CAN bus 44 connected and is controlled in a starting position so that the transfer pump 28 with the first spout and thus with the first fuel line 36 connected is. In a second position, the valve 32 so controlled that the transfer pump 28 with the second fuel line 40 connected is. In this way, the first fuel tank 20 be bridged and the transfer pump 28 can take fuel from the second fuel tank 22 to the second fuel line 40 , downstream of the first fuel tank 20 and main pump 26 , and on to the combustion engine 2 pump.

In the first fuel tank 20 is a first level sensor 46 arranged to the fuel level in the first fuel tank 20 to investigate. A second level sensor 48 is in the second fuel tank 22 arranged to the fuel level in the second fuel tank 22 to investigate. The first level sensor 46 and the second level sensor 48 are with the CAN bus 44 and the control device 42 which the transfer pump 28 and the main pump 26 controls, connected.

3 shows a flow diagram of a method for handling water in fuel in the fuel system 4 , The method according to the invention comprises the step (a) of separating water in the fuel by driving the transfer pump 28 with a first electric motor M1, so that the transfer pump 28 Fuel from the second fuel tank 22 through a pre-filter 30 pumps, the downstream of the transfer pump 28 is arranged. The deposition thus takes place in the pre-filter 30 by separating the water in the fuel from the fuel. Further, the method comprises the step (b) of conducting the separated water from the prefilter 30 to one in conjunction with the first fuel tank 20 arranged water tank 54 , By forming the water tank 54 with a larger volume than the pre-filter 30 becomes the water tank 54 not replenished in a short time, causing the internal combustion engine 2 and thus the vehicle for a substantial period of time between the emptying of the water tank 54 can be driven.

Claims (13)

Fuel system ( 4 ) for an internal combustion engine ( 2 ), whose fuel system has a first fuel tank ( 20 ), a second fuel tank ( 22 ), in conjunction with the first fuel tank ( 20 ) and the second fuel tank ( 22 ) arranged first fuel line ( 36 ), in conjunction with the first fuel tank ( 40 ) arranged second fuel line ( 40 ), a main pump ( 26 ) and a transfer pump ( 28 ), the main pump ( 26 ) for pumping fuel from the first fuel tank ( 20 ) through the second fuel line ( 40 ), and wherein the transfer pump ( 28 ) for pumping fuel from the second fuel tank ( 22 ) to the first fuel tank ( 20 ) via the first fuel line ( 36 ), characterized in that a water separation prefilter ( 30 ) downstream of the transfer pump ( 28 ) is arranged so that the transfer pump ( 28 ) pressurized fuel through the prefilter ( 30 ) and that a water tank ( 54 ) in conjunction with the first fuel tank ( 20 ) is arranged so that the water tank ( 54 ) with the prefilter ( 30 ) and separated water from the prefilter ( 30 ) receives. Fuel system according to claim 1, characterized in that a first electric motor (M1) for driving the transfer pump ( 28 ) and a second electric motor (M2) for driving the main pump ( 26 ) is arranged. Fuel system according to claim 1 or 2, characterized in that the water tank ( 54 ) in connection with the bottom of the first fuel tank ( 20 ) is arranged so that the separated water in the water tank ( 54 ) and the fuel in the first fuel tank ( 20 ) are kept separate. Fuel system according to one of the preceding claims, characterized in that the water tank ( 54 ) comprises a transparent material. Fuel system according to one of the preceding claims, characterized in that the bottom wall of the water tank ( 54 ) has an outlet through which the water tank ( 54 ) is emptied of water. Fuel system according to one of the preceding claims, characterized in that a main fuel filter ( 12 ) downstream of the main feed pump ( 26 ) is arranged. Fuel system according to one of the preceding claims, characterized in that the main pump ( 26 ) within the first fuel tank ( 20 ) is arranged. Fuel system according to one of the preceding claims, characterized in that the transfer pump ( 28 ) within the first fuel tank ( 20 ) is arranged. Fuel system according to one of the preceding claims, characterized in that the prefilter ( 30 ) within the first fuel tank ( 20 ) is arranged. Fuel system according to one of the preceding claims, characterized in that the first fuel tank ( 20 ) for receiving a smaller volume than the second fuel tank ( 22 ) is trained. Internal combustion engine ( 2 ), characterized in that this a fuel system ( 4 ) according to one of claims 1 to 10. Vehicle ( 1 ), characterized in that this a fuel system ( 4 ) according to one of claims 1 to 10. Method for handling water in fuel in a fuel system ( 4 ) for an internal combustion engine ( 2 ), whose fuel system ( 4 ) a first fuel tank ( 20 ), a second fuel tank ( 22 ), in conjunction with the first fuel tank ( 20 ) and the second fuel tank ( 22 ) arranged first fuel line ( 36 ), in conjunction with the first fuel tank ( 20 ) arranged second fuel line ( 40 ), a main pump ( 26 ) and a transfer pump ( 28 ), the main pump ( 26 ) for pumping fuel from the first fuel tank ( 20 ) through the second fuel line ( 40 ), and wherein the transfer pump ( 28 ) for pumping fuel from the second fuel tank ( 22 ) to the first fuel tank ( 20 ) via the first fuel line ( 36 ), characterized by the following steps: a) separating water into fuel by pumping fuel with the transfer pump ( 28 ) from the second fuel tank ( 22 ) via a prefilter ( 30 ) located downstream of the transfer pump ( 28 b) passing the separated water from the pre-filter ( 30 ) to one in connection with the first fuel tank ( 20 ) arranged water container ( 54 ).

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