DE102010006042A1 - Method for operating fuel evaporation restraint system, involves providing activated carbon filter, which adsorbs in loading phase of hydrocarbon vapors and desorbs by rinsing with fresh air - Google Patents

Abstract

The method involves providing an activated carbon filter (14), which adsorbs in a loading phase of hydrocarbon vapors and desorbs by rinsing with fresh air. The temperature of the activated carbon filter is increased in the regeneration phase. The temperature of the activated carbon filter is reduced in the loading phase. An independent claim is also included for a fuel evaporation restraint system.

Description

The invention relates to a fuel vapor retention system and a method for operating a fuel vapor retention system with an activated carbon filter adsorbing in a loading phase hydrocarbon vapors which are desorbed in a regeneration phase by purging with fresh air.

From the prepublished prior art, as for example in the publications US 5,957,113 . US 5,386,811 . US 4,919,103 . US 4,732,588 . US 4,598,686 . JP 2007239641 A . JP 2003314384 A . JP 60006061 A . JP 55149622 A and EP 0 656 470 A1 discloses various measures are known to improve the properties of fuel vapor retention systems in the operation of motor vehicles.

The object of the invention is to further improve the properties of a fuel evaporation restraint system during operation of a motor vehicle, in particular during operation of a hybrid vehicle or of a motor vehicle with an automatic start-stop system.

The object is achieved in a method for operating a fuel vapor retention system with an activated carbon filter, which adsorbs in a loading phase hydrocarbon vapors, which are desorbed in a regeneration phase by purging with fresh air, achieved in that the temperature of the activated carbon filter is increased in the regeneration phase. Targeted addition of heat in the regeneration phase promotes desorption. As a result, the effectiveness of the activated carbon filter, especially in critical operating conditions, can be significantly improved.

A preferred embodiment of the method is characterized in that the temperature of the activated carbon filter is reduced in the loading phase. By targeted removal of heat in the loading phase, the adsorption is favored. As a result, the effectiveness of the activated carbon filter, especially in critical operating conditions, can be significantly improved. Particularly preferably, the two measures described above are carried out combined in the regeneration phase and in the loading phase.

A further preferred exemplary embodiment of the method is characterized in that the fresh air supplied to the activated carbon filter for purging in the regeneration phase is heated in order to increase the temperature of the activated carbon filter. For heating the fresh air, for example, an inner heating coil or an outer heating mat can be used.

A further preferred embodiment of the method is characterized in that the activated carbon filter is heated in the regeneration phase by supplying hot air, in order to increase the temperature of the activated carbon filter. The hot air can be supplied to the activated carbon filter in one place or in several places.

A further preferred embodiment of the method is characterized in that the temperature of the activated carbon filter is increased by means of a Peltier element in the regeneration phase and reduced in the loading phase. As Peltier element, an electrothermal converter is called, which generates a current difference based on the so-called Peltier effect at current flow or a temperature difference at a temperature difference.

A further preferred embodiment of the method is characterized in that the activated carbon filter is regenerated by means of the Peltier element in a first operating state in a first chamber and loaded in a second chamber. In this case, heat is removed from the second chamber and fed into the first chamber. The removal of the heat promotes the absorption of the hydrocarbons in the second chamber, while the supply of heat promotes the desorption of the hydrocarbons in the first chamber.

A further preferred embodiment of the method is characterized in that the activated carbon filter is loaded in a second operating state in the first chamber with the aid of the Peltier element and regenerated in the second chamber. In the second operating state, the previously described functions of the two chambers are reversed, and the Peltier element is electrically reversed.

In a fuel evaporation restraint system, which is operated in particular according to a method described above, the above-stated object is achieved in that the activated carbon filter comprises at least two chambers which are thermally coupled to each other by at least one Peltier element. The two chambers are directly, or indirectly via another chamber, in communication with a fresh air connection. In addition, the two chambers are connectable to a suction pipe of an engine or to a fuel tank.

A preferred embodiment of the fuel vapor retention system is characterized in that a third chamber in series with the two thermally coupled by the Peltier element coupled chambers is. The first two chambers are preferably connected in parallel. The third chamber connected in series preferably serves to catch leakage currents.

A further preferred embodiment of the fuel evaporation restraint system is characterized in that the first two chambers can be connected by a valve device alternately with either a motor or a fuel tank. The valve device is designed, for example, as a 4/2-way valve with a tank connection and a motor connection and two connections for the first two chambers.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail. Show it:

1 a simplified illustration of a fuel evaporation restraint system, which is operated according to a first embodiment of the invention;

2 a fuel evaporation restraint system according to a second embodiment with a Peltier element in a first operating state and

3 the fuel evaporation restraint system 2 in a second operating state.

In 1 is an engine intake manifold 1 indicated, by which an engine of a motor vehicle air or a fuel-air mixture is supplied, as indicated by an arrow 2 is indicated. In the engine intake manifold 1 is a throttle 4 arranged. In 1 you also see one with a filling tube 6 and a fuel line 7 equipped fuel tank 8th , By an arrow 9 is hinted that the fuel from the fuel tank 8th the engine, in particular a carburetor, is supplied.

The fuel tank 8th is a fuel evaporation restraint system 10 with an activated carbon filter container 12 assigned, in which an activated carbon filter 14 is arranged. The activated carbon filter container 12 is via a motor connection cable 16 in which a tank ventilation valve 18 is arranged with the engine intake manifold 1 connectable. Via a tank connection cable 20 is the activated carbon filter container 12 to the fuel tank 8th connected. In addition, the activated carbon filter container 12 a fresh air connection 22 on.

By an arrow 25 is in 1 indicated that when refueling fuel through the filling tube 6 in the fuel tank 8th is filled. It will, as by another arrow 26 indicated is fuel vapor from the fuel tank 8th via the tank connection line 20 into the activated carbon filter 11 repressed. This will make the activated carbon filter 14 loaded with fuel vapors, in particular with hydrocarbon vapors, which is also referred to as loading phase. By another arrow 27 is indicated that filtered air at the fresh air connection 22 can escape.

In a regeneration phase of the activated carbon filter 14 flushed with fresh air through the fresh air connection 22 is fed, as by another arrow 28 is indicated. The fresh air is in a direction opposite to the loading through the activated carbon filter 14 directed. The fresh air takes the into the activated carbon filter 14 recaptured hydrocarbons. The driving force or the pressure difference for purging supplies the engine that sucks and burns the hydrocarbon-air mixture, as indicated by another arrow 29 is indicated.

For regeneration of the activated carbon filter 14 In particular, operating states with high throttling are suitable, which result in lower intake manifold pressure. However, it is precisely these engine operating states that are eliminated in a hybrid vehicle since the internal combustion engine is often switched off in these phases. In accordance with an essential aspect of the invention, measures are provided which, in particular in hybrid vehicles in critical phases or operating states in which the internal combustion engine is switched off, provide sufficient rinsing / regeneration of the activated carbon filter 14 enable.

By an arrow 31 is in 1 hinted that the activated carbon filter 14 during the regeneration phase heat is deliberately added to the temperature in the activated carbon filter 14 to increase. This can improve the quality of the rinse. By the supplied heat 31 the desorption is favored. The heat energy supplied is proportional to the regeneration efficiency.

The heat 31 can be supplied by means of hot air, for example. Alternatively or additionally, an inner heating coil can be used to the activated carbon filter 14 especially in a middle area to heat. Alternatively or additionally, a heating mat on the outside of the activated carbon filter container 12 be attached. To the heat loss through the activated carbon filter container 12 To reduce this, it can be thermally insulated from the environment.

By another arrow 32 is in 1 indicated that the loading process of the activated carbon filter 14 is optimized by the heat, the when loaded by exothermic adsorption, is discharged. The specific absorption capacity of the activated carbon filter 14 is inversely proportional to the temperature. At lower temperatures, the activated carbon filter 14 adsorb more hydrocarbon molecules. By dissipating the heat 32 increases the working capacity of the activated carbon filter 14 ,

In the 2 and 3 is a fuel evaporation restraint system 40 according to a second embodiment, in which a first chamber 41 comprising a first activated carbon filter via a Peltier element 45 with a second chamber 42 thermally coupled, which comprises a second activated carbon filter. The two chambers 41 and 42 together represent a combined activated carbon filter and are connected in parallel. About the Peltier element 45 are the two chambers 41 and 42 thermally connected.

The two chambers 41 . 42 are each via a connecting line 48 . 49 to a valve device 50 connected. The valve device 50 is designed as a 4/2-way valve to which a motor connection cable 51 and a tank connection line 52 connected.

In the in 2 shown switching position of the valve device 50 is the first chamber 41 with the motor connection cable 51 connected. The second chamber 42 is over the connection line 48 with the tank connection cable 52 connected.

In the in 3 shown switching position of the valve device 50 is the first chamber 41 over the connecting line 47 with the tank connection cable 52 connected. The second chamber 42 is over the connection line 48 with the motor connection cable 51 connected.

The first chamber 41 is over a connecting line 55 with a third chamber 60 in connection. The second chamber 42 is over a connecting line 56 also with the third chamber 60 in connection. The third chamber 60 has a fresh air connection 58 on.

In 2 is shown a first operating state in which the first chamber 41 is rinsed with fresh air. Parallel to this is the second chamber 42 loaded. By an arrow 61 is hinted that the heat in the second chamber 42 produced by adsorption, there discharged and the first chamber 41 is supplied.

Due to the heat supply, a temperature rises 63 in the first chamber 41 , At the same time, the heat dissipation reduces the temperature 64 in the second chamber 42 , Due to the higher temperature 63 is the desorption in the first chamber 41 promoted. At the same time is due to the lower temperature 64 in the second chamber 42 the absorption capacity of the activated carbon favors.

In 3 are the roles of parallel chambers 41 . 42 vice versa. The second chamber 42 is regenerated while the activated carbon filter 14 in the first chamber 41 Hydrocarbon molecules adsorbed.

In the second operating state, the Peltier element 45 electrically reversed. Thus, the direction of heat flow changes as indicated by an arrow 66 in 3 is indicated. This reduces a temperature 67 in the first chamber 41 while a temperature 68 in the second chamber 42 increases.

A state change between the two operating states in the 2 and 3 can be initiated for example via a signal from temperature elements, which are used for example at a certain distance to the fresh air side.

The third chamber 60 is so in line with the two chambers 41 . 42 switched that creepage currents are collected. According to another aspect of the invention, the chambers are 41 . 42 . 60 provided with a thermal insulation.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5957113 [0002]
• US 5386811 [0002]
• US 4919103 [0002]
• US 4732588 [0002]
• US 4598686 [0002]
• JP 2007239641 A [0002]
• JP 2003314384 A [0002]
• JP 60006061 A [0002]
• JP 55149622A [0002]
• EP 0656470 A1 [0002]

Claims (10)

Method for operating a fuel evaporation restraint system ( 1 ; 40 ) with an activated carbon filter ( 14 ), which adsorbs in a loading phase hydrocarbon vapors, which are desorbed in a regeneration phase by rinsing with fresh air, characterized in that the temperature of the activated carbon filter ( 14 ) is increased in the regeneration phase. A method according to claim 1, characterized in that the temperature of the activated carbon filter ( 14 ) is reduced in the loading phase. Method according to one of the preceding claims, characterized in that in the regeneration phase the activated carbon filter ( 14 ) is heated to rinse supplied fresh air to the temperature of the activated carbon filter ( 14 ) increase. Method according to one of the preceding claims, characterized in that the activated carbon filter ( 14 ) is heated in the regeneration phase by supplying hot air to the temperature of the activated carbon filter ( 14 ) increase. Method according to one of the preceding claims, characterized in that the temperature of the activated carbon filter by means of a Peltier element ( 45 ) is increased in the regeneration phase and reduced in the loading phase. A method according to claim 5, characterized in that the activated carbon filter by means of the Peltier element ( 45 ) in a first operating state ( 2 ) in a first chamber ( 41 ) and in a second chamber ( 42 ) is loaded. A method according to claim 6, characterized in that the activated carbon filter by means of the Peltier element ( 45 ) in a second operating state ( 3 ) in the first chamber ( 41 ) and in the second chamber ( 42 ) is regenerated. A fuel evaporation restraint system operated in particular according to a method according to one of the preceding claims, characterized in that the activated carbon filter has at least two chambers ( 41 . 42 ) by at least one Peltier element ( 45 ) are thermally coupled together. A fuel evaporation restraint system according to claim 8, characterized in that a third chamber ( 60 ) in series with the two thermally through the Peltier element ( 45 ) coupled to each other chambers ( 41 . 42 ) is switched. A fuel vapor retention system according to claim 8 or 9, characterized in that the first two chambers ( 41 . 42 ) by a valve device ( 50 ) are alternately connectable with either a motor or a fuel tank.

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