CN111102103A

CN111102103A - Tank ventilation system and method for diagnosing a tank ventilation system

Info

Publication number: CN111102103A
Application number: CN201911022122.XA
Authority: CN
Inventors: G.肖克; R.陶贝尔特; T.赫格斯; U.金默勒
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-10-26
Filing date: 2019-10-25
Publication date: 2020-05-05
Also published as: DE102018218314A1; DE102018218314B4

Abstract

The invention relates to a tank ventilation system (20). The tank venting system has a T-branch (23) with a first check valve (24) on a first end, a second check valve (25) on a second end, and a tank venting valve (26) on a third end. A temperature sensor (40) is arranged in a branching point of the T-shaped branching section (23). When the first check valve (24) is connected via a line (27) to an intake manifold (15) of an internal combustion engine (11) of a motor vehicle and the second check valve (25) is connected via a line (28) to an air supply (12) of a turbocharger (13) of the internal combustion engine (11), the tank exhaust system (20) can be diagnosed in such a way that the temperature is measured by means of a temperature sensor (40). From this temperature, a reliability check of the temperature of the internal combustion engine (11) is used, and a jamming of one of the non-return valves (24, 25) is inferred from the actuation behavior of the tank outlet valve (26).

Description

Tank ventilation system and method for diagnosing a tank ventilation system

Technical Field

The invention relates to a tank exhaust system. The invention further relates to a method for diagnosing a tank ventilation system. The invention further relates to a computer program for carrying out each step of the method and to a machine-readable storage medium which stores the computer program. Finally, the invention relates to an electronic control device configured to implement the method.

Background

In the fuel tank of a motor vehicle, volatile substances, which are essentially hydrocarbons, evaporate depending on the pressure and temperature conditions prevailing in the fuel tank and the composition of the fuel. For environmental and safety reasons, these substances must be taken and fed to the internal combustion engine of the motor vehicle for combustion. For this purpose, volatile substances are generally absorbed and temporarily stored by means of activated carbon filters. To regenerate the activated carbon filter, the substance is sucked in by the air flow and is supplied to the intake manifold of the internal combustion engine for combustion. The suction takes place by means of a negative pressure which is formed in the intake pipe on the basis of the throttling of the engine.

If the motor vehicle has a turbocharger, the activated carbon filter is regenerated during operation of the turbine by introducing the substance into the air supply upstream of the turbocharger. For this purpose, the line system of the tank ventilation system branches off behind a tank ventilation valve, which is provided for controlling the tank ventilation mass flow during the tank ventilation operation. This is achieved by means of a T-branch in which two check valves are arranged. The check valve prevents air flow between an air supply portion of the turbocharger and the intake pipe.

Legal requirements in some countries require that a possible stuck (Klemmen) of the check valve be diagnosed. This can be analyzed by means of a pressure sensor installed in the T-branch between the check valve and the tank outlet valve.

Disclosure of Invention

The proposed tank venting system has in a conventional manner a T-branch with a first check valve on a first end, a second check valve on a second end and a tank venting valve on a third end. A temperature sensor is arranged in the branching point of the T-branch, i.e. where the three pipe pieces forming the T-branch merge. The structure of the tank exhaust system is based on the idea that a T-branch is usually mounted in the motor vehicle in the vicinity of the engine. The T-branch is therefore rapidly heated to above ambient temperature by the waste heat of the internal combustion engine of the motor vehicle. When no mass flow flows through the T-branch, the temperature sensor is heated by the provided arrangement of the temperature sensor. If mass flow is present, the temperature sensor is cooled. The temperature sensor may be used to diagnose the tank exhaust system in the event of jamming of the check valve. Temperature sensors are significantly more advantageous in production than pressure sensors, which are used, for example, according to the prior art for diagnosing tank exhaust systems.

In particular, the first check valve is connected to an intake manifold of an internal combustion engine of the motor vehicle via a line, which may be referred to as an intake manifold line. The second check valve is connected to the air supply of the turbocharger of the internal combustion engine via a further line, which may be referred to as a turbo line. The further line can end there, for example, in a venturi nozzle.

Such a tank ventilation system can be diagnosed by means of a diagnostic method, in which the temperature is measured by means of a temperature sensor. The temperature is checked for reliability using the temperature of the internal combustion engine and the actuation behavior of the tank outlet valve, wherein the reliability is checked in particular by the temperature profile. The actuation characteristic indicates whether the tank outlet valve is open or closed. Jamming of one of the check valves is inferred from the results of the reliability check. The method makes use of the fact that, in different operating states of the tank exhaust system, it is possible either to expect a mass flow through the T-branch, which would result in cooling the temperature sensor below the temperature of the internal combustion engine, or to expect a mass flow, so that the temperature of the temperature sensor would substantially correspond to the temperature of the internal combustion engine. Deviations from this characteristic indicate jamming of the check valve. With the knowledge of the open state of the tank outlet valve, and with the knowledge of whether the internal combustion engine is in the turbo mode or in the intake mode, it is possible not only to locate which check valve is stuck, but also to determine whether the check valve is stuck open or stuck closed, without the tank outlet valve being damaged.

In the embodiment of the method in which the internal combustion engine is operated in turbo mode and the tank outlet valve is open, a mass flow from the activated carbon filter through the T-branch into the turbo line is anticipated. However, when the measured temperature corresponds to the temperature of the internal combustion engine within a predetermined tolerance range, the mass flow of the cooling temperature sensor is absent, so that a stuck closure of the second check valve is inferred.

In the embodiment of the method in which the internal combustion engine is operated in the intake mode and the tank outlet valve is open, a mass flow from the activated carbon filter to the intake tract is expected. When the measured temperature corresponds to the temperature of the internal combustion engine within a predetermined tolerance range, the mass flow cooling the temperature sensor is absent and it is concluded that the first check valve is stuck closed.

In the embodiment of the method in which the internal combustion engine is operated in the intake mode and the tank outlet valve is closed, no mass flow is expected via the temperature sensor. However, if cooling of the temperature sensor still occurs, so that the measured temperature is below the temperature of the internal combustion engine by at least the predetermined difference, it is concluded that the second check valve, which causes a mass flow from the turbine line to the intake line, is stuck open.

In the embodiment of the method in which the internal combustion engine is operated in turbo mode and the tank outlet valve is closed, the cooled mass flow by the temperature sensor is likewise not expected. If, however, it is noted that the measured temperature is below the temperature of the internal combustion engine by at least the predetermined difference, it is concluded that the first check valve, which leads to a mass flow from the intake line to the turbine line, is stuck open.

The computer program is provided for carrying out each step of the method, in particular when the computer program runs on a computing device or an electronic control device. Different embodiments of the method implemented on the electronic control device can be implemented without structural changes having to be performed for this. For this purpose, the computer program is stored on a machine-readable storage medium.

The electronic control unit is obtained by loading a computer program onto a conventional electronic control unit, which is set up to diagnose the tank exhaust system by means of the method.

Drawings

Embodiments of the invention are illustrated in the drawings and set forth in detail in the description that follows. Wherein:

FIG. 1 schematically illustrates a tank venting system according to an embodiment of the invention;

FIG. 2 shows a flow chart of an embodiment of a method according to the invention;

fig. 3 schematically shows a blocked line in a first fault situation of the tank ventilation system according to fig. 1;

FIG. 4 schematically shows a blocked line in a second fault situation of the tank venting system according to FIG. 1;

FIG. 5 schematically shows mass flow in a third fault situation of the tank exhaust system according to FIG. 1;

fig. 6 schematically shows the mass flow in the case of a fourth fault of the tank exhaust system according to fig. 1.

Detailed Description

In fig. 1, an engine system 10 and a tank exhaust system 20 of a motor vehicle are shown. Both systems are controlled by the electronic control device 30. The engine system 10 has an internal combustion engine 11. The internal combustion engine is supplied with ambient air through the air supply 12. A turbocharger 13 and a charge air cooler 14 are arranged in the air supply 12. Downstream of the charge air cooler 14, air is supplied to the internal combustion engine 11 via an intake line 15. In turbo operation, in which the turbocharger 13 is driven by the exhaust gas flow of the internal combustion engine 11, the air is compressed here. In the inactive intake mode of the turbocharger 13, air is drawn through the internal combustion engine 11, wherein the air flow can be adjusted by means of a throttle valve cover in the intake manifold 15. In turbine operation, a portion of the compressed air branches off downstream of the charge air cooler 14 and is supplied to the venturi nozzle 16 in the air supply 12.

The tank venting system 20 includes a fuel tank 21 of the internal combustion engine 11. The fuel tank is connected to an activated carbon filter 22 via a line, in which substances escaping from the fuel tank 21 are absorbed. The tank exhaust line leads from the activated carbon filter 22 to a T-branch 23. The T-branch has a first check valve 24 on a first end. On the second end a second check valve 25 is arranged. At the third end, a tank venting valve 26 is arranged, which is located in the tank venting line between the activated carbon filter 22 and the T-branch 23. The first non-return valve 24 enables mass flow from the T-branch 23 through the line 27 to the inlet pipe 15. The line 27 is referred to as the inlet line. Mass flow in the opposite direction is disabled. The second check valve 25 allows mass flow from the T-branch 23 through a further line 28 ending in the venturi nozzle 16. The conduit 28 is referred to as a turbine conduit. Mass flow in the opposite direction is inhibited by the second check valve 25.

The engine system 10 and the tank exhaust system 20 correspond to the conventional equipment of a motor vehicle with regard to their aforementioned components. In the present exemplary embodiment of the invention, the engine system and the tank exhaust system are however supplemented by a temperature sensor 40, which is arranged in the branching point of the T-branch 23.

Fig. 2 shows a flowchart of a method for diagnosing the tank exhaust system 20 according to an embodiment of the invention. After the method has started 51, the stuck tank outlet valve 26 is first checked 52. When such a jam is recognized, a fault record 61 is generated in the electronic control device 30 and the method is interrupted. In other cases, the tank vent valve 26 is opened 53. The temperature T measured by the temperature sensor 40 and the temperature T of the internal combustion engine 11_EAnd (7) comparing 54. Temperature T of internal combustion engine 11_EThis can be detected, for example, by means of an oil temperature sensor, not shown, of the internal combustion engine 11. When the temperature T measured by means of the temperature sensor 40 is within a predetermined tolerance range, it corresponds to the engine temperature T_EIt is further checked 55 in which operating mode the internal combustion engine 11 is located. The operation mode may be extracted from a record in the electronic control device 30. If the internal combustion engine is in the turbo mode Tu, there is the situation shown in fig. 3. The air flow generated by the turbocharger 13 should actually generate a negative pressure in the turbine line 28, by means of which a flow through the activated carbon is generatedThe filter 22 enters the mass flow of the turbine pipe 28 via a tank outlet valve 26, a T-branch 23 and a second non-return valve 25. Since the temperature sensor 40 is not cooled by mass flow to the engine temperature T_EIn the following, it is therefore pointed out that the second non-return valve 25 closes the jam, so that this jam is inferred and a corresponding fault record is generated 62. If the internal combustion engine 11 is conversely in the intake mode S, the internal combustion engine generates a negative pressure in the intake manifold 27. This negative pressure should result in a mass flow from the activated carbon filter 22 through the tank outlet valve 26, the T-branch 23 and the first check valve 24 into the inlet line 27 and in this way cool the temperature sensor 40. This is shown in fig. 4. Since this has not occurred, it is concluded that the first check valve 24 is stuck closed and a corresponding fault record is generated 63.

If the temperature T measured by the temperature sensor 40 is conversely at least within a predetermined range of the temperature T of the internal combustion engine 11_EThereafter, the tank vent valve 26 is then closed 56. It is checked 57 whether the temperature T measured by the temperature sensor 40 is now always at the temperature T of the internal combustion engine 11, also by a predetermined difference_EThe following. In this case, the operating state of the internal combustion engine 11 is queried by the electronic control device 30, and a fault record is generated 58 in the electronic control device 30 depending on the operating state. Based on the closed tank outlet valve 26, no cooling mass flow from the activated carbon filter 22 into the T-branch 23 is expected. When the temperature sensor 40 is still cooled, this is caused by the mass flow between the intake line 27 and the turbine line 28. If the internal combustion engine 11 is in the intake mode S, the mass flow from the turbine line 28 enters the intake line 27, as shown in fig. 5. This is based on the assumption that the second check valve 25 opens and jams. Thus, a stuck-open second check valve 25 is inferred, and a corresponding fault record is generated 64. If the internal combustion engine 11 is conversely located in the turbine operation Tu, air flows from the intake line 27 into the turbine line 28. This is only possible when the first check valve 24 opens to jam, which is shown in fig. 6. Thus, a stuck open first check valve 24 is inferred, and a corresponding fault record is generated 65.

On the contrary, the number of the first and second electrodes,when it is determined that the temperature T measured by the temperature sensor 40 has risen to the temperature T of the internal combustion engine 11 within the tolerance range after the closing of the tank outlet valve 26_EThen the tank venting system 20 shows the characteristics expected by the tank venting system and concludes that the two

check valves

24, 25 are normal 66.

Claims

1. Tank venting system (20) having a T-branch (23) with a first non-return valve (24) on a first end, a second non-return valve (25) on a second end and a tank venting valve (26) on a third end, characterized in that a temperature sensor (40) is arranged in the branch point of the T-branch (23).

2. Tank exhaust system (20) according to claim 1, characterized in that the first check valve (24) is connected by a line (27) to an intake pipe (15) of an internal combustion engine (11) of the motor vehicle and the second check valve (25) is connected by a line (28) to an air supply (12) of a turbocharger (13) of the internal combustion engine (11).

3. Method for diagnosing a tank exhaust system (20) according to claim 2, in which a temperature (T) is measured by means of a temperature sensor (40) and from this temperature (T) the temperature (T) of the internal combustion engine (11) is used_E) And deducing jamming of one of the check valves (24, 25) from the operating characteristics of the tank outlet valve (26).

4. A method according to claim 3, characterised in that the measured temperature (T) corresponds to the temperature (T) of the combustion engine (11) within a preset tolerance range when the tank outlet valve (26) is open_E) During operation of the internal combustion engine (11) in the turbo mode (Tu), it is concluded (62) that the second check valve (25) is closed and stuck.

5. According toA method as claimed in claim 3 or 4, characterized in that the measured temperature (T) corresponds to the temperature (T) of the internal combustion engine (11) within a predetermined tolerance range when the tank outlet valve (26) is open_E) During operation of the internal combustion engine (11) in the intake mode (S), it is concluded (63) that the first non-return valve (24) is closed and stuck.

6. A method according to any one of claims 3-5, characterised in that the measured temperature (T) is at least within the range of the temperature (T) of the combustion engine (11) by a preset difference when the tank outlet valve (26) is closed_E) In the following, during operation of the internal combustion engine (11) in the intake mode (S), it is inferred (64) that the second check valve (25) is stuck open.

7. Method according to any one of claims 3 to 6, characterized in that the measured temperature (T) is at least within a predetermined difference in magnitude at the temperature (T) of the internal combustion engine (11) when the tank outlet valve (26) is closed_E) In the following, during operation of the internal combustion engine (11) in the turbo mode (Tu), a stuck-open state of the first check valve (24) is inferred.

8. A computer program arranged to perform each step of the method according to any one of claims 3 to 7.

9. A machine-readable storage medium on which a computer program according to claim 8 is stored.

10. An electronic control device (30) which is set up for diagnosing a tank exhaust system (20) by means of a method according to any one of claims 3 to 7.