WO2013020816A1

WO2013020816A1 - Venting a fuel tank by means of a diaphragm pump

Info

Publication number: WO2013020816A1
Application number: PCT/EP2012/064675
Authority: WO
Inventors: Andreas Gutscher; Andreas Posselt; Marko Lorenz
Original assignee: Robert Bosch Gmbh
Priority date: 2011-08-05
Filing date: 2012-07-26
Publication date: 2013-02-14
Also published as: DE102011080506A1

Abstract

The invention relates to a system (1) for venting a fuel tank (3). The system (1) has a filter (5) which is connected to the fuel tank (3) and is designed to absorb fuel vapor (9). The system (1) further has a vent line (11) which connects the filter (5) to an engine air supply line (13) and is designed to conduct fuel vapor (9) from the filter (5) to the engine air supply line (13). A diaphragm pump (23) is provided on the vent line (11), said diaphragm pump being designed to vary a pressure of the fuel vapor (9) that can be found in the vent line (11).

Description

description

Venting of a fuel tank by means of a diaphragm pump prior art

Exhaust gas reduction and monitoring are important concerns of modern industries. In the automotive industry, the withdrawal of

Fuel vaporization e.g. be prevented from the fuel tank to the environment. This is done, for example, by means of an activated carbon filter (AKF), which can absorb volatile hydrocarbons.

The activated carbon filter can be regenerated by flushing with fresh air, so that its capacity is maintained. The regeneration can be done, for example, by sucking fresh air from the environment through the carbon filter. For this purpose, for example, a negative pressure in an engine air supply line, also referred to as intake manifold, prevail and a tank vent valve (TEV) must be open. A negative pressure in the engine air supply can usually be generated only when the internal combustion engine, so that a regeneration of the activated carbon filter is not possible when the engine is stopped. Furthermore, the negative pressure or the number of negative pressure phases in the

Engine air supply e.g. for smaller engines with turbocharging (downsizing) no longer sufficient for the sufficient regeneration of the activated carbon filter. Even in hybrid vehicles with an internal combustion engine as a range extender or plug-in hybrids of the internal combustion engine is inactive for longer periods, so that a regeneration of the activated carbon filter is not possible.

Disclosure of the invention

There may therefore be a need for an improvement of the tank ventilation, which even at a low pressure gradient between activated carbon filter or

Fresh air and engine air supply is functional. This object can be achieved by the subject matter of the present invention according to the independent claims. Advantageous embodiments of the present invention are described in the dependent claims.

In the following, features, details and possible advantages of a device according to embodiments of the invention will be discussed in detail.

According to a first aspect of the invention, a system for venting a fuel tank is presented. The system has a filter, e.g. one

Activated carbon filter, which is on the one hand connected to a fuel tank and on the other hand connected via a vent line with an engine air supply line. The filter is designed to receive fuel vapor from the fuel tank and save if necessary. The vent line is designed to direct fuel vapor from the filter to the engine air supply line. At the

Vent line is arranged a diaphragm pump which is designed to vary the pressure of the fuel vapor located in the vent line.

In other words, the idea of the present invention is based on in phases in which there is no sufficient pressure difference between the

Fuel tank and a suction pipe is provided to provide a pressure regulation in the vent line by means of a diaphragm pump. To operate the diaphragm pump, for example, a small part of the pumping power of an existing in the system electric fuel pump (EKP) can be used. Alternatively, the diaphragm pump by means of an independent

Electric pump operated. The pressure in the vent line may be e.g. be increased or decreased by bending a membrane towards the inside of the vent line and away from the interior of the vent line away. Thanks to the system according to the invention, the filter can be actively regenerated more efficiently. The active regeneration of the filter also allows for systems with limited fresh air purge phases of the filter

adequate regeneration. For example, the system of the present invention may be used for safe and successful filter regeneration in systems with smaller engines (downsizing) and in hybrid systems, e.g. Electric vehicles with

Range extender, contribute to a reliable regeneration of the filter. The system for venting the fuel tank can be used, for example, in vehicles, in particular in motor vehicles and preferably in hybrid vehicles. The fuel tank may be filled with a fuel such as gasoline. The fuel can secrete fuel vapors or fuel gases. The fuel vapors may be, for example, low boiling hydrocarbons.

The fuel vapors from the fuel tank become a filter, e.g. an activated carbon filter, passed through a fuel vapor line and in the filter

saved. From the filter, the fuel vapors can pass through a vent line to an engine air supply line. The engine air supply may consist of a piping system which communicates with the outside or fresh air. The engine air supply can also be referred to as air path or intake manifold. The engine air supply line is designed to supply air to an internal combustion engine. In the engine air supply line, a turbocharger may be arranged, which comprises for example a compressor and is executed, a

Internal combustion engine compressed air supply.

Between the filter and the engine air supply line a diaphragm pump is arranged on the vent line. The diaphragm pump can be integrated directly into the vent line or alternatively be connected to the vent line via another line.

The membrane pump has a membrane, which can be deflected hydraulically, pneumatically or mechanically, for example. In the relaxed state, the membrane can be in one plane. On a first side of the membrane may be a working medium, which can deflect the membrane out of the plane. If, for example, the pressure on the working medium is increased, the working medium presses against the membrane and deflects it. If the pressure on the working medium is reduced, the membrane can be deflected in the direction of the working medium. The other side of the

Membrane, also referred to as the second side, is in contact with the vent line. If the membrane is now deflected by the working medium in the direction of the vent line, the volume of the vent line is reduced.

For example, located in the vent line fuel vapors are pressed in this way in the direction of the engine air supply. From the engine air supply, the fuel vapors can be supplied together with fresh air to the engine.

If the pressure on the working medium is reduced, the membrane moves in its normal state or beyond in the direction of the working medium. As a result, the volume in the vent line is increased, and there is a negative pressure on the side of the vent line. This leads to

Fuel vapor is sucked out of the filter into the vent line.

Altogether, the pressure of the fuel vapor or the pressure of the fuel vapor-air mixture in the vent line can be varied or regulated in this way.

According to one exemplary embodiment of the invention, the membrane pump has a membrane which is in contact with a working medium on a first side and with a conveying medium on a second side. The fluid is a befindlichem in the vent line fuel vapor.

The membrane can be designed, for example, as a film or skin and act as a separating layer between working and conveying medium. The membrane can be impermeable or impermeable both for the working medium and for the pumped medium. For example, the diaphragm can seal the first side of the diaphragm pump airtight or hermetically from the second side of the diaphragm

Disconnect diaphragm pump.

The working medium may e.g. Fuel, for example, over a

Fuel line from the fuel tank can be guided to the first side of the membrane. Alternatively, the working fluid may be, for example, water, in particular cooling water from a cooling system or cooling circuit. Furthermore, the working medium may be, for example, any liquid which is used, for example, in a motor vehicle. In the embodiment shown here is the diaphragm pump operated hydraulically. In alternative embodiments, the membrane may also be pneumatically or mechanically deflectable.

According to a further embodiment of the invention, the system further comprises a pump, in particular a fuel pump, e.g. a

Electric fuel pump (EKP), on. This is designed to pump the working fluid from a working medium container. For example, For example, the pump may deliver fuel from a fuel tank to an internal combustion engine. The pump is connected via a line, e.g. connected via a fuel line to the diaphragm pump. In particular, the fuel line may connect the fuel tank to the second side of the membrane. In this case, the fuel pump can be arranged in the fuel line. The fuel pump may be designed to drive the diaphragm pump via the fuel line. The

Arbeitsmediumbehältnis can thereby a fuel tank or a

Be Kühlwasservorratstanktank.

In this way, a small part of the pump power of the existing in the system electric fuel pump can be used to

Operate diaphragm pump.

According to a further embodiment of the invention, a changeover valve is arranged on the line between the diaphragm pump and the pump. The switching valve is executed, in a first position the

Working medium from the working medium container to the diaphragm pump

pass. Further, the switching valve is designed to pass the working fluid in a second position from the diaphragm pump to the working medium container.

The switching valve can be designed for example as a 3-2-way valve. The switching valve can be controlled or switched, for example, by a control unit. If the changeover valve is in its first position, i. opened in the direction of the membrane, it is deflected or bent and located in the vent line fuel vapor is in the direction

Engine air supply line pressed. If the changeover valve is open in its second position, ie in the direction of the working medium container, then the diaphragm of the diaphragm pump moves toward its neutral state. The example of a fuel As a working medium in this case takes place a fuel return into the fuel tank. The movement of the membrane to its neutral state to or beyond leads to the formation of a vent line side negative pressure. This, in turn, causes fuel vapor to flow from the filter into the volume on the first side of the membrane.

According to a further embodiment of the invention, the system further comprises a control unit, e.g. is arranged on a motor controller or integrated therein. The control unit is connected to the switching valve e.g. connected bidirectionally. That the control unit can both receive signals from the changeover valve and send signals to the changeover valve. The control unit is designed for operating point-dependent control of the switching valve.

Furthermore, the further electrical switching valves, such as a first and second check valve and a tank venting valve can be controlled by the control unit depending on an operating point of the internal combustion engine and thus possibly depending on a negative pressure in the engine air supply line.

According to a further embodiment of the invention, a cylinder, for example a plunger, between the diaphragm pump and the

Fuel pump arranged in the fuel line. The cylinder is designed to transmit a pressure of the fuel in the fuel line to the membrane.

The cylinder may correspond to a hydraulic ratio of the electric fuel pump and increase the pumping power of the diaphragm pump. The

Hydraulic translation can cause, for example, "high pressure and low flow rate" to "low pressure and high pressure

For example, the cylinder on the fuel side could have a (circular) area with a small diameter which is subjected to high pressure, for example about 3.5 bar, on the side facing the diaphragm, also referred to as purge side , the cylinder could have an area with a larger diameter, which is acted upon by a lower pressure, for example about 2 bar, since a stroke of the cylinder remains the same, thus ensuring a higher flow rate on the purge side Cylinder rinsing of the filter is also possible in a charged state. According to a further embodiment of the invention is at the

Vent line between the filter and the diaphragm pump arranged a first valve. The first valve is designed to be a flow of

To prevent fuel vapor from the diaphragm pump in the direction of the filter.

The first valve may preferably be designed as a check valve, in particular as a directional valve, which blocks a return flow of fuel vapors to the filter. In this case, the first valve may be designed, for example, as a spring-loaded check valve, in particular as a ball check valve. A flow of fuel vapors from the filter to the diaphragm pump or in the direction of the engine air supply line is not prevented by the first valve.

The first valve may be important, for example, when the diaphragm is deflected in the direction of the vent line, so that the pressure in the vent line is increased and the fuel vapor is pressed in the direction of the engine air supply line. In this situation, the first valve prevents backflow of the fuel vapor under increased pressure back to the filter.

According to a further embodiment of the invention is a

Tank Bleeder Valve (TEV) located on the vent line between the filter and the diaphragm pump. The first valve is between the

Tank vent valve and the diaphragm pump arranged.

The tank vent valve is designed to adjust the amount or volume of fuel vapor that can be removed from the filter into the vent line. This can be done, for example, that the opening cross section of the tank venting valve is controlled by a control unit. The tank vent valve can therefore be designed as a controllable shut-off valve, which is controlled by the control unit

Can regulate the flow rate of the fuel vapors. If necessary, the tank breather valve can be tightly closed.

The arrangement of the first valve between the tank-venting valve and the diaphragm pump can prevent a backflow of the fuel vapors in the direction of the tank-venting valve. According to a further embodiment of the invention is at the

Vent line between the diaphragm pump and the engine air supply line provided a second valve. The second valve is designed to conduct a flow of fuel vapor from the engine air supply line in the direction of

Prevent diaphragm pump.

The second valve is preferably designed as a check valve and may be designed similar to the first valve. The second valve can be advantageously used when the diaphragm of the diaphragm pump on her

Neutral state and generates a negative pressure in the vent line, so that fuel vapor flows through the filter and optionally via a tank vent valve in the volume on the second side of the membrane. A backflow of fuel vapors, which are already in the engine air supply line or in the intake manifold, is prevented by the second valve.

Other features and advantages of the present invention will become

Expert from the following description of exemplary

Embodiments, which should not be construed as limiting the invention, with reference to the accompanying drawings.

Fig. 1 shows a cross section through a tank ventilation system with a

Extraction of fuel vapors using an existing

pressure drop

Fig. 2 shows a cross section through an inventive

Tank deaeration system with a suction of the fuel vapors by means of a diaphragm pump

All figures are merely schematic representations of devices according to the invention or of their components according to embodiments of the invention. In particular, distances and size relationships are not shown to scale in the figures. In the various figures, corresponding elements are provided with the same reference numbers. FIG. 1 shows a cross section through a known tank ventilation system. Here are located in a fuel tank 3, a fuel 7 and fuel vapor 9 or fuel gases. The fuel tank 3 is connected via a line with a filter 5, namely an activated carbon filter. In the filter 5, the fuel vapors 9 are stored. The capacity of the filter 5 is limited, so that it must be regenerated. For this purpose, the filter 5 via a vent line 11 with an engine air supply line 13, which is also referred to as air path, airway or intake manifold connected. In the

Vent line 11, a tank vent valve 17 may be provided, which can be controlled for example via a control unit. To this

In this way, the tank venting valve 17 can regulate the amount of fuel vapors 9 that pass through the venting line 11.

The engine air supply line 13 may, for example, be in communication with fresh air 15, for example air outside the vehicle. The fresh air 15 is guided via an air mass meter 16. On the way to the engine 19, the air can pass through a charge air cooler 21. Fresh air 15 ^" can be sucked through the filter 5 by a pressure gradient between the activated carbon filter 5 and the engine air supply line 13. By this flushing, the fuel vapors 9 stored in the filter 5 are released and supplied to the engine air supply line 13 via the vent line 11 and the tank venting valve 17 an engine controller, the amount of fuel that is supplied to the engine 19 from the tank ventilation system in the metering of

Remove fuel quantity.

In the embodiment shown in Figure 1, a sufficient pressure gradient between the activated carbon filter and the engine air supply line 13 is necessary. In many systems, such as systems with smaller engines and turbocharging (downsizing) can not be sufficient

Pressure gradient are generated or the proportion of available time with pressure drop is too low to a sufficient regeneration of

Activated charcoal filter.

In the system 1 according to the invention for venting the fuel tank 3 shown in FIG. 2, a regeneration of the filter 5 or a venting of the fuel tank 3 is also possible in the case of restricted rinsing phases or in the case of low or low purging phases not existing pressure gradient between the fuel tank 3 and engine air supply line 13 ensured.

For this purpose, a diaphragm pump 23 is provided on the vent line 11, which can vary the pressure of the vapor in the vent line 11 fuel vapor 9. The diaphragm pump 23 has a diaphragm 25 with a first side 27 and a second side 29. On the first page 27 is the

Membrane 25 with a working fluid 31 in contact. On the second side 29, the membrane 25 is in contact with a conveying medium 33. The

Working fluid 31 is fuel 7 and the fluid 33 is

Fuel vapor 9.

The system 1 further comprises a fuel pump 35, which is designed for example as an electric fuel pump and is driven by means of an electric motor 37. The fuel pump 35 is executed, fuel 7 from the

To pump fuel tank 3 to the engine 19. For this is the

Fuel pump 35 disposed in a line between the fuel tank 3 and the engine 19. An arrangement of the electric fuel pump 35 in the fuel tank 3 is also possible.

For driving the diaphragm pump 23, a small part of the pump power of the fuel pump 35 is used. For this purpose, a fuel line 39 is provided, which branches off, for example, from the line between the fuel tank 3 and the engine 19. The fuel line 39 connects the

Fuel pump 35 with the diaphragm pump 23. Further, in the fuel line

39 a switching valve 43 is provided. The switching valve 43 can be switched between two positions. In a first position, fuel flow from the fuel tank 3 to the diaphragm pump 23 is possible. In the second position, a fuel return from the diaphragm pump 23 to

Fuel tank 3 via a return line 41 possible.

Is the switching valve 43 in its first position, that is in the direction

Membrane 25 is opened, it is bent in the direction of the vent line 11, and the fuel vapor 9 therein is in the direction

Engine air supply line 13 pressed. A flow of the fuel vapor 9 in

Direction of the tank ventilation valve 17 and the filter 5 is by means of a first valve 45 prevents. The first valve 45 is designed as a check valve.

When the switching valve 43 is opened in the direction of the return line 41, that is, the switching valve 43 is in the second position (not shown in Fig. 2), the diaphragm 25 moves to its neutral state. This is associated with formation of a fuel vapor side vacuum. In this second position of the switching valve 43, fuel vapor 9 flows out of the filter 5 via the tank venting valve 17 into the volume above the diaphragm 25, i. on the second side 29 of the membrane. A backflow from the

Engine air supply line 13 or from the intake manifold is prevented by means of a second valve 47. The second valve 47 is designed as a check valve.

Optionally, a turbocharger 49 may be arranged on the engine air supply line 13. This can compress the air before it is supplied to the engine 19.

In the exemplary embodiment in FIG. 2, fuel 7 is used as the working medium 31. Alternatively, any media used in a motor vehicle can be used as the working medium 31. For example, can

Cooling water can be used as a working medium and cooling water lines and containers in the system 1.

In conclusion, it should be noted that terms such as "comprising" or the like are not intended to exclude that other elements or steps may be envisioned.Furthermore, it should be understood that "a" or "an" does not exclude a multitude It should further be noted that the reference signs in the claims should not be construed as limiting the scope of the claims.

Claims

claims

A system (1) for venting a fuel tank (3) comprising the system (1)

a filter (5) communicating with the fuel tank (3) and adapted to receive fuel vapor (9);

a vent line (1 1), the filter (5) with an engine air supply line

(13) connects and executes fuel vapor (9) from the filter (5) to

To guide engine air supply line (13);

characterized in that

on the vent line (1 1) a diaphragm pump (23) is provided, which is designed to vary a pressure of the in the vent line (1 1) located fuel vapor (9).

2. System (1) according to claim 1,

the diaphragm pump (23) having a diaphragm (25);

wherein the membrane (25) on a first side (27) with a

Working medium (31) and on a second side (29) with a

Conveying medium (33) is in contact;

wherein the conveying medium (33) of the in the vent line (1 1) located fuel vapor (9).

The system (1) of any of claims 2 and 3, further comprising

a pump (35) configured to pump the working fluid (31) from a working fluid reservoir (3);

the pump (35) being connected to the diaphragm pump (23) via a conduit (39);

wherein the pump (35) is designed to drive the diaphragm pump (23) via the line (39). 4. System (1) according to claim 4, wherein on the line (39) between the diaphragm pump (23) and the pump (35), a switching valve (43) is arranged;

wherein the switching valve (43) is designed in a first position, the working medium (31) from the working medium container (3) to

Let through the diaphragm pump (23);

wherein the switching valve (43) is designed in a second position, the working medium (31) from the diaphragm pump (23) to

Pass through the working fluid container (3).

System (1) according to claim 4,

wherein the working medium (31) is fuel (7);

wherein the pump (35) is a fuel pump (35) which is executed

To pump fuel (7) from a fuel tank (3);

wherein the conduit (39) is designed as a fuel line (39).

The system (1) of claim 5, further comprising

a control unit connected to the switching valve (43);

wherein the control unit is designed to control the switching valve (43) in dependence on an operating point of an internal combustion engine.

The system (1) according to any one of claims 3 to 6, further comprising a cylinder disposed between the diaphragm pump (23) and the pump (35) in the conduit (39);

wherein the cylinder is designed to transmit a pressure of the working medium (31) in the conduit (39) to the membrane (25).

System (1) according to one of claims 1 to 7,

wherein at the vent line (1 1) between the filter (5) and the

Diaphragm pump (23), a first valve (45) is provided;

wherein the first valve (45) is executed, a flow of the fuel vapor

(9) from the diaphragm pump (23) in the direction of filter (5) to prevent.

The system (1) of claim 8, further comprising

a tank vent valve (17) disposed on the vent line (1 1) between the filter (5) and the diaphragm pump (23); wherein the tank vent valve (17) is executed, the amount of

Fuel vapor (9), which is guided by the filter (5) in the vent line (1 1) to adjust;

wherein the first valve (45) is disposed between the tank vent valve (17) and the diaphragm pump (23).

10. System (1) according to one of claims 1 to 9,

wherein on the vent line (1 1) between the diaphragm pump (23) and the engine air supply line (13), a second valve (47) is provided;

wherein the second valve (47) is designed to be a flow of

Fuel vapor (9) from the engine air supply line (13) in the direction

Diaphragm pump (23) to prevent.