METHOD FOR TESTING A FUEL SYSTEM OF A VEHICLE WITH AN INTERNAL COMBUSTION ENGINE, IN PARTICULAR A MOTORCYCLE, AND MOTORCYCLE

Description

[0001] The invention relates to a method for testing a tank system of a vehicle with an internal combustion engine, in particular a motorcycle, and to a motorcycle.

[0002] Investigations by the California Air Resources Board (CARB) have revealed that a significant proportion of organic compound emissions caused by motorcycles while riding are due to leaking or faulty fuel tank systems.

[0003] The fuel tank of a vehicle powered by an internal combustion engine is connected to the environment to equalize pressure differences that occur, for example, during refueling, fuel consumption, or due to temperature fluctuations. Air exchange in both directions must be possible. In a common application, this is achieved with a tank vent valve connected to an air intake line of the internal combustion engine, as well as a fresh air supply to the tank. To prevent unburned fuel from escaping into the environment, an activated carbon filter is usually installed in the fresh air line. This filter captures and temporarily stores the fuel contained in the outgoing air in gaseous form. Consequently, this activated carbon filter must be regenerated regularly.For this purpose, the tank vent valve is opened in a controlled manner and the fuel from the activated carbon filter is fed into the air supply line and thus into the internal combustion engine.

[0004] In the passenger car sector, tank inspection systems that check the proper functioning of the tank venting valve and the tightness of the overall system are already standard.

[0005] The generic DE 40 03 751 A1 discloses a tank venting valve for a motor vehicle in which a vent line of an absorption filter can be controlled and shut off, and a negative pressure in the tank is measured for diagnostic purposes.

[0006] DE 195 36 646 A1 and DE 10 2009 036265 A1 show further diagnostic systems for tank vents.

[0007] Tank systems for motorcycles are described in US 2020 / 198717 A1 and US 2010 / 078241 A1.

[0008] An alignment of the requirements with this standard is also planned for motorcycles.

[0009] The object of the invention is to enable the inspection of a tank system in a simple and cost-effective manner.

[0010] This problem is solved by a method for testing the fuel system of a vehicle with an internal combustion engine. The fuel system comprises a fuel tank, a fuel tank vent valve, a filter located in the flow path between the fuel tank and the fuel tank vent valve, and a suction line leading from the fuel tank vent valve to an internal combustion engine. The fuel tank vent valve is opened for a predetermined angular range corresponding to the rotation angle of the engine's crankshaft during an intake stroke of a cylinder of the engine, over several intake strokes, whereby fluid is drawn from the fuel tank through the filter into the suction line. A pressure upstream of the fuel tank vent valve is measured to determine pressure values, and these pressure values ​​are evaluated.

[0011] During the intake stroke, a vacuum is created in the air supply line. Since the air supply line is in flow connection with the suction line, a vacuum also forms at the fuel tank vent valve. When the fuel tank vent valve opens, fluid is therefore drawn from the fuel tank through the filter and into the suction line.

[0012] The angle-based control of the fuel tank vent valve opening results in a predictable pressure change that can be reliably measured even with short valve opening times. This minimizes the impact of the vent valve's opening time on engine performance.

[0013] The opening of the fuel tank vent valve is carried out, for example, over 5 to 25 intake strokes, particularly around 10. It has been found that this method yields meaningful pressure readings with minimal impact on engine operation.

[0014] The tank vent valve is opened, for example, for a percentage of 10% to 50%, particularly 15% to 30% of the intake stroke.

[0015] The position of the angular range within the intake stroke is freely selectable, allowing the use of different operating points with varying expected vacuum values. This makes it possible to tap into an operating point-dependent suction line vacuum and to variably adjust the expected vacuum within a certain range. The specified angular range can therefore be selected with respect to both the magnitude and the start of the tank vent valve's opening, depending on the internal combustion engine's operating point.

[0016] It is preferable to isolate the tank system from ambient pressure to allow for precise control of the pressure. For example, a shut-off valve that allows fresh air to reach the filter is closed while the tank vent valve remains open. The shut-off valve can remain closed throughout the entire testing procedure.

[0017] The measured pressure values ​​can be used, for example, to determine whether there is a leak in the tank system, such as if the maximum vacuum achieved is lower than expected.

[0018] The measured pressure values ​​can also indicate a malfunction of the tank venting valve, for example if the pressure fluctuations over several intake strokes are weaker or stronger than expected.

[0019] Preferably, a pressure sensor is positioned between the tank and the filter to determine the pressure values. The pressure is then measured upstream of the filter.

[0020] The intake fluid is preferably introduced into the air supply line to the internal combustion engine downstream of a throttle valve, thus bypassing it. The position of the throttle valve therefore has no direct influence on the measured pressure values, even though the throttle valve defines the operating point and thus indirectly affects its control.

[0021] Preferably, the aspirated fluid is always fed to a single cylinder of the internal combustion engine or a two-cylinder boxer engine. In this way, the measured pressure values ​​are not influenced by the movement of other cylinders of the internal combustion engine in a phase-shifted cycle.

[0022] The invention also relates to a motorcycle with the features of claim 10 and accordingly with a tank system designed to perform a method described above.

[0023] The invention can easily be applied to all internal combustion engines with only one cylinder or in the form of a boxer engine.

[0024] However, when the aspirated fluid is fed into a single cylinder of the internal combustion engine, in whose intake stroke the angular range for the opening of the tank venting valve lies and which is used to generate the vacuum in the suction line, the method is in principle suitable for all internal combustion engines.

[0025] Since the tank vent valve is opened for a predetermined angular range of the crankshaft's rotation angle, and thus the expected vacuum is known, a very accurate evaluation of the determined pressure values ​​is possible despite the short opening times of the tank vent valve.

[0026] The invention is described in more detail below with reference to an exemplary embodiment and the accompanying figures. The drawings show: Figure 1 a schematic representation of a tank system of a motorcycle according to the invention for carrying out a method according to the invention; and Figure 2 a schematic representation of an angle-based control of a tank venting valve of the tank system from Figure 1 .

[0027] Figure 1 shows a tank system 10 of an internal combustion engine (not shown) of a motorcycle not shown in detail.

[0028] The invention is generally applicable to vehicles with an internal combustion engine and a fuel tank system. It is particularly preferred for use in motorcycles. Therefore, it will be explained below using a motorcycle as an example.

[0029] For the purposes of this application, a motorcycle means all single-track vehicles powered by an internal combustion engine, i.e., both typical motorcycles and scooters as well as, for example, three-wheeled vehicle types.

[0030] The tank system 10 comprises a fuel tank 12 (the fuel used here is gasoline-based and suitable for gasoline engines). The fuel tank 12 is connected via lines 14 to a filter 16, in this case an activated carbon filter, and downstream of the filter 16 to a tank vent valve 18.

[0031] From the tank venting valve 18, a suction line 20 leads to a throttle valve 22 in an air supply line of the internal combustion engine (not shown in detail), the suction line 20 opening into the air supply line upstream of the throttle valve 22.

[0032] The suction line 20 is arranged in such a way that the fluid flowing in it is always supplied to a single, fixed cylinder of the internal combustion engine.

[0033] The filter 16 is connected to a fresh air line 24 in which a shut-off valve 26 is arranged, which can prevent the supply of fresh air to the filter 16 and the outflow of air from the filter 16 into the environment.

[0034] Furthermore, the tank system 10 includes a pressure sensor 28, which is located in the fuel tank 12 or in the line 14, here between filter 16 and fuel tank 12.

[0035] The tank vent valve 18 is connected to a control unit 30. The control unit 30 is also connected to all other components of the tank system 10, in particular the pressure sensor 28, as well as other vehicle components. These include, for example, a lambda sensor 32 in an exhaust system of the internal combustion engine (not shown).

[0036] The fuel tank 12 is connected to one or more injectors 36 of the (not shown) cylinder(s) of the internal combustion engine via a fuel supply line 34.

[0037] The internal combustion engine here is a single-cylinder engine or a boxer engine, in particular a two-cylinder boxer engine.

[0038] During normal operation of the internal combustion engine, the pressure in the fuel tank 12 changes due to fuel withdrawal via the fuel supply line 34 and the injection valve 36, fuel replenishment in the fuel tank 12, and temperature changes. This can result in both negative and positive pressure relative to the surroundings. The shut-off valve 26 in the fresh air line 24 is normally open, allowing fresh air to flow into or escape from the fuel tank 12. In the event of positive pressure in the fuel tank 12, the gaseous fuel components are retained in the filter 16, so that only air flows out of the fresh air line 24.

[0039] Filter 16 is regularly regenerated. For this purpose, the tank vent valve 18 is opened in the manner specified by the control unit 30, and filter 16 is purged with fresh air. The resulting fluid, a fuel-air mixture, is supplied to the internal combustion engine via the suction line 20.

[0040] When a diagnostic procedure is performed to check the tank system 10, in which the tank system 10 is checked for leaks and / or the proper functioning of the tank vent valve 18, the tank vent valve 18 is briefly opened according to a predetermined scheme. This is in Figure 2 clarifies.

[0041] The diagram shows a vacuum p in the intake line 20, plotted against the rotation angle α of a crankshaft driven by the internal combustion engine. The diagram depicts the intake stroke of the cylinder connected to the intake line 20. During the intake stroke, a defined, known, angle-dependent vacuum p is generated. A range of angles that can be used in principle to carry out the process is indicated by the hatching.

[0042] This known relationship is used to define a predetermined angular range Δα during which the tank vent valve 18 is opened by the control unit 30. The angular range Δα can be arbitrarily set within the usable angular range, allowing for the utilization of different operating points that yield varying vacuum values. The magnitude of the angular range Δα is also arbitrarily selectable, provided it does not exceed 720°, meaning the tank vent valve 18 closes at least once every 720°. Therefore, the start of the predetermined angular range Δα, i.e., the initial angle α at which the tank vent valve 18 opens, and the magnitude of the angular range Δα, i.e., the angle difference between the angles at which the tank vent valve 18 opens and closes, can be freely selected within the usable angular range at the discretion of a person skilled in the art.

[0043] The tank vent valve 18 can, for example, be open for a percentage of approximately 10% to 50%, and in particular approximately 15% to 30%, of the intake stroke, which corresponds to an angle range Δα of approximately 20° to 90° or approximately 30° to 55°, respectively. The starting point of the angle range Δα can be set by a person skilled in the art at any suitable angle α during the intake stroke.

[0044] The tank venting valve 18 is opened over several intake strokes, for example 5 to 25 intake strokes, preferably over the same angular range Δα each time.

[0045] Simultaneously with the opening of the tank vent valve 18, the shut-off valve 26 in the fresh air line 24 is closed, so that no ambient air can be drawn into the fuel tank 12.

[0046] While the tank venting valve 18 is open, the pressure profile is measured with the pressure sensor 28 and pressure values ​​are determined, which are used for evaluation.

[0047] The evaluation can be carried out in control unit 30.

[0048] For example, a leak can be inferred if the pressure does not drop as much as expected, or a malfunction of the tank vent valve 18 can be inferred if the pressure fluctuation over several intake strokes is smaller than expected. Of course, any other suitable evaluations can also be carried out.

[0049] Since the unambiguous relationship between the pressure values ​​and the operating point of the cylinder responsible for generating the vacuum is always known, an accurate diagnosis is possible even with small angular ranges Δα, which correspond to short opening times of the tank venting valve 18.

Claims

1. Method for checking a tank system (10) of a vehicle with an internal combustion engine, in particular a motorcycle, wherein the tank system (10) comprises a fuel tank (12), a tank ventilation valve (18), a filter (16) arranged in the flow path between the fuel tank (12) and the tank ventilation valve (18), and a suction line (20) which leads from the tank ventilation valve (18) to an internal combustion engine, characterized by the steps: • opening the tank ventilation valve (18) in each case for a predetermined angular range (Δα) of a rotation angle (α) of a crankshaft of the internal combustion engine during an intake stroke of a cylinder of the internal combustion engine, over several intake strokes, wherein fluid is sucked from the fuel tank (12) into the suction line (20) via the filter (16), • measuring a pressure upstream of the tank ventilation valve (18) in order to determine pressure values, and • evaluating the pressure values.

2. Method according to claim 1, wherein the opening of the tank ventilation valve (18) is carried out over 5 to 25 intake strokes.

3. Method according to one of the preceding claims, wherein the tank ventilation valve (18) is opened over a percentage of 10 % to 50 %, in particular 15 % to 30 % of the intake stroke.

4. Method according to one of the preceding claims, wherein the predetermined angular range (Δα) in magnitude and beginning of the opening of the tank ventilation valve (18) is selected in dependence on an operating point of the internal combustion engine.

5. Method according to one of the preceding claims, wherein a shut-off valve (26), through which fresh air reaches the filter (16), is closed while the tank ventilation valve (18) is open.

6. Method according to one of the preceding claims, wherein the presence of a leak in the tank system (10) is inferred from the pressure values.

7. Method according to one of the preceding claims, wherein a malfunction of the tank ventilation valve (18) is inferred from the pressure values.

8. Method according to one of the preceding claims, wherein the sucked fluid is fed downstream of a throttle valve (22) into an air supply line leading to the internal combustion engine.

9. Method according to one of the preceding claims, wherein the sucked fluid is always fed to a single cylinder of the internal combustion engine or to a two-cylinder boxer engine.

10. Motorcycle with a tank system (10), wherein the tank system (10) is designed to carry out a method according to one of the preceding claims and comprises a fuel tank (12), a tank ventilation valve (18), a filter (16) arranged in the flow path between the fuel tank (12) and the tank ventilation valve (18), a suction line (20) which leads from the tank ventilation valve (18) to an internal combustion engine of the motorcycle, and a shut-off valve (26) which can prevent the supply of fresh air to the filter (16), and a control unit (30), wherein the tank ventilation valve (18) is opened in a controlled manner by the control unit (30) in the predetermined angular range (Δα) of the rotation angle (α) of the crankshaft, and wherein the internal combustion engine is a single-cylinder engine or a two-cylinder boxer engine.