SE537487C2 - Combustion engine fuel system, internal combustion engine with such a fuel system, vehicles with such a fuel system and a method of dampening pressure fluctuations in a fuel system - Google Patents

Abstract

Summary The invention relates to a fuel system (4) for an internal combustion engine (2), which fuel system (4) comprises a fuel filter device (24) arranged between an electric motor-controlled low-pressure pump (22) and a high-pressure pump (26), the fuel filter device (24) comprising a filter housing (24). 40), in which a filter element (32) and an accumulator (34) are arranged to vapor pressure fluctuations in the fuel system (4). An electrically controllable valve (36) is further provided with the fuel filter device (24) for controlling the accumulator (34). The invention also relates to an internal combustion engine (2) with such a fuel system (4), vehicles (1) with such a fuel system (4) and a method for vapor pressure fluctuations in a fuel system (4).

Description

Fuel systems have an internal combustion engine, an internal combustion engine with such a fuel system, vehicles with such a fuel system and a process for steaming pressure fluctuations in a fuel system.

FIELD OF THE INVENTION The present invention relates to a fuel system for an internal combustion engine, an internal combustion engine with such a fuel system, a vehicle with such a fuel system and a method for vaporizing pressure fluctuations in a fuel system.

BACKGROUND OF THE INVENTION AND KNOWLEDGE TECHNOLOGY Internal combustion engines, such as diesel or otto engines, are used in several types of applications and vehicles today, for example in heavy vehicles, such as trucks or buses, cars, motor boats, ships, ferries or ships. Internal combustion engines are also used in industrial engines and / or motor-driven industrial robots, power plants, such as e.g. electric power plants that include a diesel generator, and in locomotives.

Internal combustion engines can be powered by diesel or petrol. These engines are equipped with a fuel system to transport the fuel Than one or more fuel tanks to the internal combustion engine injection system. The fuel system comprises one or more fuel pumps which can be driven mechanically by the internal combustion engine or driven by an electric motor. The fuel pumps create an industry flow and pressure to transport the industry to the internal combustion engine's injection system, which Ulf & the industry to the internal combustion engine's combustion chamber.

Fuel pumps powered by an electric motor provide the ability to operate the fuel pump independently of the internal combustion engine speed and thus allow a wider control range than a mechanically driven pump, which is controlled by the speed. The fuel volume supplied via the electric fuel pump can thus be better adapted to the combustion engine's fuel inlet at the same time as the fuel pump's energy inlet and overcapacity can be minimized. In order to minimize energy consumption and thus fuel consumption, it is necessary to let the fuel pump operate at as low a speed as possible and pump the smallest possible volume of fuel into the fuel system. However, this means that the fuel system becomes susceptible to rapid fluctuations in the combustion engine's fuel needs. In operating cases where the needs of the internal combustion engine, for example, quickly fluctuate, a small industry volume to a large industry volume, demands are made that the industry pump just as quickly changes the industry volume it pumps to the internal combustion engine. If this does not happen, the consequence will be a temporary pressure drop in the fuel system, which risks affecting the combustion engine's emissions and operation. Correspondingly, a delay in the fuel pump control can cause occasional pressure spikes as the internal combustion engine's fuel needs change rapidly -Iran a large fuel volume to a small fuel volume. These pressure fluctuations can also lead to responsibilities to control the fuel pump, which affects fuel consumption. This is a problem that can arise when, for example, driving in hilly environments.

Various methods and systems have been proposed in the prior art for vaporizing pressure fluctuations in industrial systems. For example, document JP10227269 A discloses a fuel system for an internal combustion engine, which comprises a fuel filter with an accumulator, arranged between a low pressure pump and a high pressure pump. The accumulator comprises a gas-filled spring and has the purpose of vaporizing pressure fluctuations in fuel which is returned from the high-pressure pump to the fuel filter.

Furthermore, document DE2725787 C3 describes an industry system comprising a device for vapor pressure fluctuations of the industry which is supplied to the dirty side of an industry filter. The device comprises an accumulator below a spring-supported membrane which is affected by the incoming fuel and vaporizes any fluctuations. The fuel is then passed on to a filter element and then further out into the fuel system.

Despite known solutions in the field, there is still a need to further develop a fuel system, which helps to dampen pressure fluctuations and thereby reduces fuel consumption and minimizes the risk of damage to the fuel system. SUMMARY OF THE INVENTION The object of the present invention is to provide a fuel system for an internal combustion engine, which allows a flexible control of the fuel supply and which reduces the parasite losses.

The object of the invention is also to provide a fuel system for an internal combustion engine which vaporizes pressure fluctuations in the fuel system.

It is a further object of the invention to provide a fuel system for an internal combustion engine which is compact and space essential.

A further object of the present invention is to provide a fuel system for an internal combustion engine which minimizes fuel consumption.

Furthermore, it is an object of the present invention to provide a fuel system for an internal combustion engine which minimizes the risk of damage in the occurrence of fuel leakage.

A further object of the present invention is to provide a fuel system in which operating conditions can be detected before the fuel pressure has reached the essentials of others. These objects are achieved with an industry system as defined in claim 1 and a method for regulating an industry system as defined in claim 10.

According to the invention, the above objects are achieved with a fuel system for an internal combustion engine which comprises a fuel filter device arranged between a single engine controlled low pressure pump and a high pressure pump.

The fuel filter device comprises a filter housing, in which a filter element and an accumulator are arranged to vapor pressure fluctuations in the fuel system. Furthermore, an electrically controllable valve is provided in the fuel filter device to control the accumulator.

The invention also relates to an internal combustion engine and a vehicle comprising the system described above.

According to another aspect, the invention relates to a method for vaporizing pressure fluctuations in a fuel system, which fuel system comprises a fuel filter device arranged between an electric motor-controlled low-pressure pump and a high-pressure pump, used in the fuel filter device comprising a filter housing in the fuel system and accustomed to the procedure, the steps include: (a) identifying the occurrence of operating cases with rapidly changing fuel supply when there is a risk of pressure fluctuations in the fuel system, (b) controlling an electrically controllable valve so that the accumulator is activated and the pressure fluctuation is damped.

DETAILED DESCRIPTION OF THE INVENTION The invention is described below with reference to the industry system and method generally described above. By arranging an electric motor-controlled low-pressure pump in a fuel system, a wider control range is allowed with a mechanical pump, which is usually driven and controlled by an internal combustion engine and above all by the speed of the internal combustion engine.

The electric motor-controlled low-pressure pump can be controlled against other parameters than motor speed, such as industry filter efficiency and pressure in the industry lines. In order to optimize fuel consumption, the electric motor-controlled low-pressure pump should be operated at as low a speed as possible and deliver as small a fuel volume as possible in the fuel system. However, this means that the fuel system becomes susceptible to rapid fluctuations in the internal combustion engine's fuel demand, as the negative pressure pump must be quickly regulated in order to be adapted to the actual fuel demand. There is some delay between the internal combustion engine changing the fuel demand and the low pressure pump speed control, which leads to temporary pressure fluctuations in the fuel system. By arranging an accumulator in the fuel filter device, a fuel system is provided, which vaporizes pressure fluctuations in the fuel system and which in this way can minimize fuel consumption without being affected by the varying fuel needs of the internal combustion engine. Furthermore, the steaming of pressure fluctuations results in a more stable control of the low-pressure pump, which in turn leads to lower fuel consumption.

By arranging an electrically controllable valve of the fuel filter device, all passages to and from the accumulator can be closed and opened so that the function of the accumulator can be controlled between inactive and active in a flexible manner. By controlling the valve based on predetermined parameters, a fuel system is achieved where the accumulator is only active in certain specific operating cases when it is really needed, which minimizes the fuel system's energy access and thus minimizes fuel consumption. In the event of an operation when the internal combustion engine's fuel needs change rapidly Than a small amount of fuel to a larger amount of fuel, a delay arises in the regulation of the legal pressure punch and pressure drop arises in the fuel system. The electrically controllable valve is then controlled so that the passages to and from the accumulator. In the event of an operation, the combustion engine's fuel requirements quickly change from a large amount of fuel to a smaller amount of fuel below the delay in the regulation of the legal pressure pump, a temporary pressure spike or a pressure surplus. The electrically controllable valve is then controlled so that the passages to and the Than accumulator are opened and excess fuel is supplied to the accumulator instead of the other fuel system and thus the pressure spike is steamed. In the event of an operation when the fuel pressure tame to the internal combustion engine is required, the valve is suitably controlled so that the accumulator is filled with a pressurized fuel volume corresponding to the delay between the legal pressure pump control and the combustion engine's change in fuel demand. In this way, the accumulator is ready to supply pressurized fuel to the industry system in the event of a possible pressure drop. The accumulator can suitably be designed so that there is room left for receiving excess industry volume when a possible pressure nail arises. The volume of the accumulator can be, for example, between 0.5-10 liters, preferably between 0.5-1.5 liters, but even larger volumes are possible if space is available.

The electrically controllable valve also entails a safety aspect in that the accumulator can be deactivated, for example in the event of industry leakage in the accumulator or in the industry system. In this way, the industry from the accumulator is prevented from leaching out to the environment and thus an industry system is created, which minimizes the risk of damage at the occurrence of industry industry leakage.

The electrically controllable valve is preferably a solenoid valve but may be any electric valve.

The accumulator is preferably arranged at the clean side of the fuel filter device, i.e. at the outlet of the fuel filter device. Furthermore, the accumulator is preferably arranged integrated with the filter element in order in this way to provide a compact and space-essential fuel filter device and thus a compact and space-essential fuel system.

Furthermore, the accumulator suitably comprises a cylinder, which is divided into two chambers by a piston. The piston preferably has a spring arranged on the side which is not in contact with fuel, which spring determines the fuel pressure which the accumulator provides. The spring can be, for example, mechanical or a gas pressure spring. A lamp, for example an o-ring, is arranged around the periphery of the piston to seal the chamber comprising the spring against the fuel.

By arranging a non-return valve, for example a non-combustion valve, at the inlet to the accumulator, a flow control is provided where fuel is supplied to the accumulator through a larger opening than through which fuel flows out of the accumulator. The throttling of the fuel flow out of the accumulator medic & that the pressure in the fuel supplied to the fuel system is constant. Lamply, non-return valves in the form of, for example, diaphragm valves are also arranged at the outlet of the filter element, in order to prevent the pressurized fuel Than the accumulator is led back to the filter element and the low-pressure pump.

The electrically controllable valve is arranged in connection with a control unit which is suitably connected to a CAN bus. The other control units of the vehicle can in turn also be connected to the CAN bus and thereby the control unit of the valve can receive information from the other control units. This information can suitably be used as control parameters when controlling the valve. The control unit of the valve can be either a separate unit only for controlling the valve and the armed accumulator or it can be connected to the control unit of the low pressure pump. The control unit of the low-pressure pump is suitably constituted by the control unit of the electric pressure pump controlling the electric motor.

Preferably, a pressure sensor is arranged downstream of the industry filter device. The pressure sensor feeds the fuel pressure according to the fuel filter device and is arranged via the 7 CAN bus in connection with the valve control unit so that the control unit can decide whether activation of the accumulator is necessary. Alternatively, a pressure sensor is arranged downstream of the low pressure pump and upstream of the industry filter device or both upstream and downstream of the industry filter device. The pressure sensor preferably comprises control logic and is in direct connection with the CAN bus. Alternatively, the pressure sensors are arranged in connection with the control unit of the low-pressure pump, which in turn is connected to the CAN bus and thereby to the control unit of the valve.

The electrically controllable valve of the fuel filter device is suitably controlled by the control unit based on parameters such as GPS for vehicle position, topographic data, n notor speed, vehicle load, nnotor load, vehicle speed, accelerator pedal, fuel pressure before and after the fuel filter device, industry temperature, pump speed or similar parameters. and when there is a risk of pressure fluctuations in the industry system. These parameters can be obtained via the CAN bus from other control units of the vehicle. By detecting these operating cases before the industry pressure has reached another level, the accumulator can be activated at an early stage and the pressure fluctuations can be evaporated. For example, the valve control unit can identify an upcoming downhill slope, which means that the internal combustion engine's fuel demand during engine braking is rapidly reduced. The valve is then controlled so that the passages to and Than accumulator are opened (the accumulator is activated) and the accumulator is filled / charged with excess fuel. In the same way, the valve control unit can identify an upcoming uphill slope, which means that the combustion engine's fuel demand increases, and the valve is controlled so that the accumulator is activated and pressurized fuel from the accumulator is added to the fuel system at the uphill! Dolan.

Further advantages of the invention will become apparent from the following detailed description of the exemplary embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS In the following, as an example, preferred embodiments of the invention are described with reference to the accompanying drawings, in which: Fig. 1 shows a schematic side view of a vehicle comprising an internal combustion engine fuel system according to the present invention; Fig. 3 shows a circuit diagram of a branch system according to the present invention, Fig. 3 shows a cross-sectional view of a branch filter device according to the present invention, Fig. 4 shows a flow chart of a method for vapor pressure fluctuations in a branch system according to the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION Fig. 1 shows a schematic side view of a vehicle 1, which vehicle comprises a fuel system 4 for an internal combustion engine 2 according to the present invention.

The internal combustion engine 2 is connected to a gearbox 6, which is connected to the drive wheel 8 of the vehicle 1 via a transmission. The vehicle also comprises a chassis 10. Fig. 2 shows a wiring diagram for a fuel system 4 for an internal combustion engine 2 according to the present invention. The fuel system 4 comprises a fuel tank 20, a low pressure pump 22, a fuel filter device 9 24, a high pressure pump 26 and an internal combustion engine 2. The low pressure pump 22 pumps fuel from the fuel tank 20 through the downstream fuel filter device 24 and on to the high pressure pump pump 2. The low pressure pump 22 is driven by an electric motor M1, which comprises a control unit (not shown), which is arranged in connection with a CAN bus 30. The fuel filter device 24 comprises a filter element 32 through which fuel from the fuel tank 20 is filtered. Downstream of the filter element 32 is an accumulator 34 arranged to vaporize pressure fluctuations of the fuel pressure pump 22. An electrically controllable valve 36 is arranged downstream of the filter element 32 to control the accumulator 34. The electrically controllable valve 36 is preferably a solenoid valve and is arranged in connection with a control unit 28, sonn via connection to the CANbus 30 communicates with other control units of the vehicle 1. Thus, the control unit 28 of the valve 36 can obtain control parameters Than other units of the vehicle 1, such as topographic data, engine speed, vehicle load, engine load, vehicle speed, accelerator pedal, fuel pressure fore and according to the industry filter device, industry temperature, pump speed or similar parameters. The valve 36 can be controlled so that the passages to and from the accumulator 34 are opened or closed, which in this way activates or deactivates the accumulator 34. At the inlet / outlet of the accumulator 34, a non-return valve 38 and a throttle valve are arranged. More details about the valves of the fuel filter device 24 are described in Figure 3. On the rear sides of the fuel filter device 24, pressure sensors 42, 44 are arranged to detect the fuel pressure before and after the fuel filter device 24. The pressure sensors 42, 44 include control logic and star in connection with the CAN bus 30. instead of their own control logic at the pressure sensors, they could be connected to the control logic of the static pressure pump's electric motor (M1) (not shown).

Fig. 3 shows a cross-sectional view of the fuel filter device 24 according to the present invention. The fuel filter device 24 comprises a filter housing 46 in which the filter element 32 and the accumulator 34 are arranged. The accumulator 34 is arranged on the clean side of the fuel filter device 24, which means that the fuel - before the fuel tank 20 is first filtered through the filter element 32 and then can flow into the accumulator 34 or further out into the fuel system 4. How the fuel flows through the fuel filter device 24 is illustrated by arrows. At the outlet of the filter element 32, non-return valves 48, for example in the form of diaphragm valves, are arranged. In this way, pressurized fuel from the accumulator 34 is prevented from flowing back into the filter element 32 and towards the negative pressure pump 22. The accumulator 34 comprises a cylinder 50 which is divided into two chambers by a piston 52. The piston 52 receives inflowing fuel on one side and has on the opposite side a spring 54 arranged. The spring 54 may be a mechanical spring or a gas pressure spring, which is compressed when the accumulator 34 is filled with fuel which presses against the piston 52. The piston 52 thus moves along a direction A under the influence of fuel and the spring 54. The spring 54 thus determines the industry pressure as the accumulator 34 achieves. Around the periphery of the piston 52 a seal 56 is arranged, for example an o-ring, so that the fuel does not reach the chamber in which the spring 54 is arranged. At the inlet to the accumulator 34 there are non-return valves 38, for example in the form of diaphragm valves, arranged and a throttle valve 40. Fuel can flow into the accumulator 34 through the diaphragm valves 38 and the throttle valve 40 but can only flow out of the accumulator 34 through the throttle valve 40. In this way a constant pressure of the fuel in the accumulator 34. The electrically controllable valve 36 is arranged substantially coaxially with the accumulator 34 and comprises a movable member 58 which can frame along the direction A. The valve 36 can be controlled so that the movable member 58 moves towards or away from the accumulator 34 and rods / inactivates and thus deactivates the accumulator 34. In the activated state of the accumulator 34, the valve 36 is controlled so that a passage is provided between the movable member 58 and the inlet of the accumulator 34. Filtered fuel can then flow into the passage, through the diaphragm valve 38 and the throttle valve 40 further into the accumulator 34 or out through the throttle valve 40 and the passage and further out into the fuel system 4. In the deactivated state of the accumulator 34 the valve 36 is controlled so that the movable member 58 is against the inlet of the accumulator 34 and no fuel is allowed to pass between the movable member 58 and the inlet of the accumulator 34.

Fig. 4 shows a flow chart of a method for vaporizing pressure fluctuations in the fuel system 4 according to the present invention. The method according to the invention comprises the step (a) of identifying the occurrence of operating cases with rapidly changing industry access when there is a risk of pressure fluctuations in the industry system 4. Furthermore, the method comprises the step (b) of controlling the electrically controllable valve 36 so that the accumulator 34 is activated and the pressure fluctuation is evaporated.

Step (a) may further comprise including a pressure sensor 44 identifying the fuel pressure after the fuel filter device 24 and thereby determining if pressure fluctuations occur.

Step (a) may also include identifying operating conditions based on parameters such as GPS for vehicle position, topographic data, engine speed, vehicle load, engine load, vehicle speed, accelerator pedal, fuel pressure, industry temperature or pump speed as the combustion engine's 2 fuel requirements vary rapidly and risk of pressure fluctuations.

Step (b) may further comprise, at the identified risk of pressure drop, controlling the valve 36, so that the accumulator 34 is activated and pressurized fuel at the accumulator 34 can be supplied to the fuel system 4 and thus evaporate the pressure drop.

Step (b) may also comprise, at the identified risk of pressure spikes, controlling the valve 36, so that the accumulator 34 is activated and excess fuel can be collected at the accumulator 34 and thus steam the pressure spike. The stated components and features set forth above may, within the scope of the invention, combine with the above-mentioned embodiments. 12

Claims (1)

A fuel system (4) comprises an internal combustion engine (2), which fuel system (4) comprises a fuel filter device (24) arranged between an electric motor controlled low pressure pump (22) and a high pressure pump (26), used in the fuel filter device (24) comprises a filter housing (46), in which a filter element (32) and an accumulator (34) integrated with the filter element (32) are arranged for vapor pressure fluctuations in the fuel system (4), characterized in that an electrically controllable valve (36) is arranged in the industry filter device ( 24) for controlling the accumulator (34), the electrically controllable valve 36 comprising a movable member 58 being able to move substantially coaxially (A) with the accumulator 34 and thereby activate / deactivate the accumulator. Fuel system according to claim 1, characterized by the aft accumulator (34) is arranged on the clean side of the fuel filter device (24) and thus receives filtered fuel. A fuel system according to claim 1 or 2, characterized in that the accumulator (34) comprises a cylinder (50) which is divided into two chambers by a piston (52). A fuel system according to any one of the preceding claims, characterized in that the electrically controllable valve (36) is arranged in connection with a control unit (28) and a CAN bus (30). A fuel system according to any one of the preceding claims, characterized in that a non-return valve (38) is arranged for supplying fuel into the accumulator (34). Fuel system according to one of the preceding claims, characterized by the electrically controllable valve (36) being controlled on the basis of parameters that can identify operating cases when the combustion engine (2)'s fuel requirements vary rapidly and when there is a risk of pressure fluctuations in the fuel system (4). vehicle position, topographic data, engine speed, vehicle load, engine load, vehicle speed, accelerator pedal, industry pressure, industry temperature or pump speed. A fuel system according to any one of the preceding claims, characterized in that it comprises a pressure sensor (44) for all identifying the fuel pressure after the fuel filter device (24). An internal combustion engine (2) can be characterized by any one comprising a fuel system (4) according to any one of claims 1-7. Vehicle (1) characterized by all it comprises an industry system (4) according to any one of claims 1-7. A method for all vapor pressure fluctuations in a fuel system (4), which fuel system (4) comprises a fuel filter device (24) arranged between an electric motor controlled low pressure pump (22) and a high pressure pump (26), the fuel filter device (24) comprising a filter housing (46). ), in which a filter element (32) and an accumulator (34) are arranged to remove all vapor pressure fluctuations in the fuel system (4), used in the process comprising the steps of: 1. identifying the occurrence of operating cases with rapidly changing industry access and the risk of pressure fluctuations (4) is present, 2. control an electrically controllable valve (36) so that all the accumulator (34) is activated and the pressure fluctuation is evaporated. A method according to claim 10, used in step (a) comprising all by means of a pressure sensor (44) identifying the fuel pressure after the fuel filter device (24) and thereby detecting if pressure fluctuations occur. Method according to claim 10, used in step (a), all based on parameters such as GPS for vehicle position, topographic data, engine speed, vehicle load, 14 engine load, vehicle speed, accelerator pedal, fuel pressure, fuel temperature or pump speed. speed and risk of pressure fluctuations in the fuel system (4). A method according to any one of claims 10-12, used in step (b) comprising, at the identified risk of a pressure drop, controlling the valve (36) so that pressurized fuel in the accumulator (34) can be supplied to the fuel system (4) and then evaporate. the pressure drop. A method according to any one of claims 10-12, used in step (b) comprising, at the identified risk, receiving a pressure nail, controlling the valve (36) so that excess fuel can collect in the accumulator (34) and then steam the pressure nail. 1/4 I co 2/4 1. sr 3/4 A36 24 48 46