TANK SYSTEM FOR A MOTOR VEHICLE

Abstract

A tank system (1) for a motor vehicle having an internal combustion engine to which fuel is supplied from a tank (2), wherein the tank (2) is assigned, in a ventilation path to the atmosphere (7), a flushable filter device (6, 6) for being loaded with hydrocarbon vapors of the fuel. The filter device (6, 6) has multiple mutually separate activated carbon filters (6). All of the activated carbon filters (6) are connected permanently in parallel. In this way, the ventilation resistance from the tank in the direction of the atmosphere can be kept low.

Claims

1. A tank system for a motor vehicle having an internal combustion engine and a tank that supplies fuel to the internal combustion engine, a ventilation path having a common inlet extending from the tank, first and second inlet branch lines of substantially equal lengths extending from the common inlet and configured for dividing a gas flow from the common inlet into substantially identical partial gas flows, first and second mutually separate activated carbon filters that are substantially identical to one another, the first and second activated carbon filters being provided respectively with first and second inlets communicating respectively with the first and second inlet branch lines, the first and second activated carbon filters further being provided respectively with first and second outlets separate from the respective first and second inlets, and the ventilation path further having first and second outlet branch lines of substantially equal lengths extending respectively from the first and second outlets of the activated carbon filters and a common outlet communicating with the first and second outlet branch lines and extending to the atmosphere, no valves being disposed in the first and second outlet branch lines so that the first and second activated carbon filters of the ventilation path are connected permanently in parallel for receiving the substantially identical first and second partial gas flows, the tank system further comprising a feed line extending from the common outlet to the internal combustion engine for selectively flushing hydrocarbon vapors from the first and second activated carbon filters to the internal combustion engine, whereby a flow distance from the tank to the feed line is the same through each of the activated carbon filters.

2. The tank system of claim 1, wherein the first and second mutually separate activated carbon filters of the ventilation path are the only activated carbon filters of the ventilation path.

3. The tank system of claim 1, wherein the tank is pressurized.

4. The tank system of claim 2, wherein the ventilation path is a first ventilation path, and wherein the tank system further comprises a second ventilation path having a second common inlet communicating with the tank, third and fourth inlet branch lines of substantially equal lengths extending from the second common inlet and configured for dividing a gas flow from the second common inlet into third and fourth substantially identical partial gas flows, third and fourth substantially identical activated carbon filters, the third and fourth activated carbon filters being provided respectively with third and fourth inlets communicating respectively with the third and fourth inlet branch lines, the third and fourth activated carbon filters further being provided respectively with third and fourth outlets separate from the respective third and fourth inlets, and the second ventilation path further having third and fourth outlet branch lines of substantially equal lengths extending respectively from the third and fourth outlets of the respective third and fourth activated carbon filters of the second ventilation path, a second common outlet communicating respectively with the third and fourth outlet branch lines and extending to the atmosphere, no valves being disposed in the third and fourth outlet branch lines so that the third and fourth activated carbon filters are connected permanently in parallel for receiving the substantially identical third and fourth partial gas flows.

5. The tank system of claim 4, wherein the second ventilation path communicates with the atmosphere during fueling of the vehicle, and the first ventilation path communicates with the atmosphere during operation of the vehicle.

6. The tank system of claim 1, wherein said tank system is a tank system of a hybrid vehicle, of a plug-in hybrid vehicle or of a motor vehicle with a start-stop device.

7. A motor vehicle comprising: an internal combustion engine; a tank that supplies fuel to the internal combustion engine; a ventilation assembly having a common inlet extending from the tank, first and second inlet branch lines of substantially equal lengths extending from the common inlet and configured for dividing a gas flow from the common inlet into substantially identical first and second partial gas flows, and first and second flushable activated carbon filter devices for retaining hydrocarbons in vapors from the fuel in the tank, the first and second flushable activated hydrocarbon filter devices in the ventilation assembly being substantially identical to one another and being provided respectively with first and second inlets connected respectively to the first and second inlet branch lines, the first and second flushable activated carbon filter devices further being provided respectively with first and second outlets spaced respectively from the first and second inlets, the ventilation assembly further having first and second outlet branch lines of substantially equal lengths extending respectively from the first and second outlets of the respective first and second activated carbon filter devices and a common outlet communicating with the first and second outlet branch lines of the respective first and second activated carbon filter devices of the ventilation assembly and extending to the atmosphere, no valves being disposed in the first and second outlet branch lines so that the first and second flushable activated carbon filter devices are connected permanently in parallel for receiving the substantially identical first and second partial gas flows; and a feed line extending from the common outlet to the internal combustion engine for selectively burning hydrocarbon vapors flushed from the first and second activated carbon filter devices to the internal combustion engine, whereby a flow distance from the tank to the feed line is the same through each of the activated carbon filters.

8. The motor vehicle of claim 7, wherein the ventilation assembly is a first ventilation assembly, and the motor vehicle further comprising a second ventilation assembly having a second common inlet extending from the tank, third and fourth inlet branch lines extending from the second common inlet and configured for dividing a gas flow from the second common inlet into third and fourth substantially identical partial gas flows and third and fourth flushable activated carbon filter devices for retaining hydrocarbons in vapors from the fuel in the tank, the third and fourth flushable activated hydrocarbon filter devices in the second ventilation assembly being substantially identical and being provided respectively with third and fourth inlets connected respectively to the third and fourth inlet branch lines, the third and fourth flushable activated hydrocarbon filter devices being provided respectively with third and fourth outlets spaced respectively from the third and fourth inlets, third and fourth outlet branch lines extending respectively from the third and fourth outlets and a second common outlet communicating with the third and fourth outlet branch lines and extending to the atmosphere, no valves being disposed in the third and fourth outlet branch lines so that the third and fourth flushable activated carbon filter devices are connected permanently in parallel for receiving the substantially identical third and fourth partial gas flows.

9. The motor vehicle of claim 8, wherein the second ventilation assembly is assigned to a ventilation path to the atmosphere during fueling of the vehicle, and the first ventilation assembly is assigned to a ventilation path to the atmosphere during operation of the vehicle.

10. The motor vehicle of claim 7, wherein the tank is a pressurized tank system.

11. The motor vehicle of claim 7, wherein the tank is a non-pressurized tank system.

12. The motor vehicle of claim 7, wherein the motor vehicle is a hybrid vehicle, a plug-in hybrid vehicle or a motor vehicle with a start-stop device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a first exemplary embodiment of the parallel arrangement of activated carbon filters in the tank system for the motor vehicle.

[0018] FIG. 2 shows a second exemplary embodiment of the parallel arrangement of activated carbon filters in the tank system for the motor vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The tank systems 1 shown in FIGS. 1 and 2 are used in a hybrid vehicle, a plug-in hybrid vehicle or a motor vehicle with a start-stop device. The vehicle is identified generallyy by the numeral 100 in FIGS. 1 and 2.

[0020] The tank system 1 of FIG. 1 has a tank 2 for fuel. The tank 2 has a filler neck 3 that can be closed off. Fuel lines 20 extend from the tank 2 to an internal combustion engine 22 of the motor vehicle are not shown. Hydrocarbon vapors of the fuel accumulate in the tank 2 during fueling of the tank and during operation of the vehicle and the internal combustion engine. These hydrocarbon vapors are conducted via a ventilation path 12 to the atmosphere. The ventilation path 12 is formed by a ventilation line 4 that is connected to the tank 2 and which, proceeding from the tank 2, splits into two inlet branch line portions 5 of equal lengths and identical cross sections. A valve (not shown) may be in the ventilation line 4, but no valves are in the inlet branch line portions 5. Each inlet branch line portion 5 is connected to an inlet of an activated carbon filter 6. The two activated carbon filters 6 are separate from one another and are connected permanently in parallel. The filter device formed by the two activated carbon filters 6 can be flushed from time to time so that the hydrocarbon vapors bound therein are conducted to the internal combustion engine 22 via feed lines 24 for burning so that the filter device is emptied. The reference numeral 7 denotes the atmosphere to which the ventilation path 12 runs from the tank 2 and the activated carbon filters 6. The two activated carbon filters 6 are connected for example via outlet branch line portions 8 of equal lengths and identical cross sections and an adjoining, common line 9 to the atmosphere 7. A valve (not shown) may be in the common line 9, but no valves are in outlet branch line portions 8. With this configuration, a flow distance from the tank 2 to the common line 9 is the same through each of the activated carbon filters 6.

[0021] The tank system 1 is designed so that the tank 2 is pressurized to reduce the vapor generation in the tank during operation and during fuelling. In the ideal case, the tank 2 is completely closed off. The tank 2 therefore is pressurized by a pressure-holding valve and protected against negative pressure by a negative pressure protection valve. The pressurization with the hold pressure is desirable to minimize the vapor emissions. Thus, the resistance in the ventilation path 12 of the activated carbon filter must be lowered. For this reason, the two activated carbon filters 6 connected permanently in parallel are arranged in the ventilation path 12. These are preferably two identical activated carbon filters 6 and are loaded, and likewise flushed, in accordance with the volume flow distribution. Small deviations of the components with respect to one another are inevitable. Thus, it is not possible to obtain exactly identical loadings and regeneration. Thus, the total absorption capacity of the two activated carbon filters 6 is slightly larger than the absorption capacity of a single, large activated carbon filter.

[0022] The embodiment according of FIG. 2 differs from FIG. 1 merely in that two ventilation paths 10, 11 run from the tank 2 to the atmosphere. Each ventilation path is assigned a pair of activated carbon filters 6. Thus four activated carbon filters 6 are provided, which may self-evidently also differ. One ventilation path 10 is provided for the fueling function and the other ventilation path 11 is provided for the ventilation function during operation of the motor vehicle and of the internal combustion engine. This permits selective or simultaneous loading of the activated carbon filters 6 during the fueling function and during operation.

[0023] The components that correspond in both embodiments are denoted by the same reference numerals in FIGS. 1 and 2.

[0024] The resistance during the ventilation of the tank is made up of different components. For example, a resistance during the tank ventilation is generated for example by lines, valves and the like, and also by the resistance of the activated carbon filters 6. Further resistances during the tank ventilation are generated due to the line conditions and the like between the activated carbon filters 6 and the atmosphere 7.