CN108120557B

CN108120557B - Leak inspection apparatus for tank assembly

Info

Publication number: CN108120557B
Application number: CN201711235369.0A
Authority: CN
Inventors: M·洛伦茨; A·波塞尔特; A·古切尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2016-11-30
Filing date: 2017-11-30
Publication date: 2021-07-06
Anticipated expiration: 2037-11-30
Also published as: CN108120557A; DE102016223838A1

Abstract

The invention relates to a leak inspection apparatus for inspecting a tank assembly having a tank for leaks, comprising: a pressure chamber; a first piston and a second piston arranged in the pressure chamber; a drive device for moving the first piston and/or the second piston; a ventilation line leading into the pressure chamber, which is connected to the atmosphere, wherein a sealing seat is formed on a port of the ventilation line leading into the pressure chamber, wherein the port can be released and closed by the second piston; a pretensioning element arranged between the first piston and the second piston for pretensioning the first piston against the second piston; a stop between the first piston and the second piston, wherein the pretensioning element presses the second piston against the first piston against the stop; a connection, which is designed to be connected to the tank assembly, wherein the first piston is designed to increase the pressure in the pressure chamber when the second piston closes the opening of the ventilation line on the sealing seat. The invention also relates to a tank ventilation assembly.

Description

Leak inspection apparatus for tank assembly

Technical Field

The invention relates to a leak inspection device for checking a tank assembly having a tank, in particular a tank assembly of a vehicle, for leaks. The invention also relates to a tank ventilation assembly comprising the inventive leak check device and to an internal combustion engine having such a tank ventilation assembly.

Background

Tank ventilation assemblies are known from the prior art in different configurations. In order to comply with the limit value of the emission of boil-off gas, the fuel tank of the vehicle has a tank ventilation system. The tank ventilation system includes an activated carbon filter for adsorbing fuel vapors leaking out of the tank ventilation line and includes a connecting line connecting the activated carbon filter with the internal combustion engine. A tank ventilation valve is arranged in the connecting line, which releases and closes the connecting line. Furthermore, a ventilation line is provided which leads from the atmosphere to the carbon filter in order to be able to flush the carbon filter. For leak testing, an air pump is also provided which places the enclosed volume of the tank assembly under pressure. The flow direction for driving the air pump can be evaluated and a leak can be inferred. Alternatively, the pressure value of a pressure sensor measuring the pressure in the closed volume of the tank assembly can also be evaluated. The pressure holding capacity of the enclosed area of the tank assembly is monitored in a determined system. However, an additional influencing variable is the gas evolution of the fuel. In the case of a leak, gas emissions and runoff may be superimposed on the leak and may lead to incorrect identification. Another problem is the different tank sizes, which may additionally also be filled at different filling levels, so that separate solutions for different tanks must often be provided here. This means additional costs and development effort. Furthermore, a leak testing device is known from EP 0789809B 1, which has a pump device which is operated in a first mode in which an incomplete pressure build-up is carried out and in a second mode in which a complete pressure build-up is carried out.

Disclosure of Invention

In contrast, the inventive leak check apparatus for checking a tank assembly having a tank, having the features of the present invention, has the advantage of being able to provide a very compact and low-cost solution for tank leak diagnostics. In particular, it is not necessary to provide several leak-testing device variants for different tank sizes, but all tank sizes can be tested independently of their filling level by means of the same leak-testing device. This results in a great cost advantage in terms of design and production. Furthermore, the invention makes it possible to improve the selectivity of the leak test by a simple matching of the pressure level to different operating conditions, in particular different filling levels in the tank. This can significantly reduce the number of error diagnoses during operation. According to the invention, it is also possible to reduce the noise generation during the leak test, so that, for example, the vehicle driver does not feel disturbed by the leak test. According to the invention, this is achieved by: the leak check apparatus has a pressure chamber and a first piston and a second piston arranged in the pressure chamber. A drive device is provided for moving the first piston and/or the second piston. Furthermore, a ventilation line into the pressure chamber is provided, which communicates the pressure chamber with the atmosphere. A sealing seat is formed on an opening of the ventilation line into the pressure chamber, wherein the opening can be released and closed by the second piston. Furthermore, a pretensioning element is present, which is arranged between the first piston and the second piston in order to pretension the first piston against the second piston. A stop is arranged between the first piston and the second piston, wherein the pretensioning element presses the second piston against the first piston against the stop. Furthermore, a connection is formed on the pressure chamber, which connection is designed for connection to a tank assembly. The first piston is designed to increase the pressure in the pressure chamber when the second piston closes the opening of the ventilation line. By closing the ventilation line, the pressure chamber is closed, so that the pressure in the pressure chamber can be increased by further movement of the first piston. In this case, a leakage in the tank arrangement can be inferred from the course of the pressure increase and/or from the energy balance of the drive for moving the first piston and/or the second piston. The invention also has the advantage that the overpressure can be limited in a simple manner by means of said assembly with the first piston and the second piston, whereby damage to the tank assembly components can be avoided at the time of pressure check.

The embodiment of the invention shows a preferred embodiment of the invention.

Preferably, the stop has a first stop surface directed radially inward on the first piston and a second stop surface directed radially outward on the second piston. In this case, the two stop surfaces are set up to abut against one another as long as the first piston and the second piston can move freely.

Preferably, the drive means is a drive means adapted to cause linear movement of the first and second pistons.

It is further preferred that the drive device comprises an electric motor which is designed to move the first piston and/or the second piston axially.

Furthermore, it is preferred that the drive device comprises a spindle mechanism which converts a rotary motion of the electric motor into a linear motion of the first piston and/or the second piston. Preferably, the output shaft of the electric motor is connected to a threaded spindle which engages in a threaded opening in one of the two pistons.

Alternatively, instead of a screw mechanism, the drive means preferably comprises a rocker lever or a rocker assembly or the like which causes the movement of the first piston and/or the second piston.

Further alternatively, the drive means comprises a curved track element having a curved track, which causes movement of the first piston and/or the second piston.

Still further alternatively, the drive means for moving the first piston and/or the second piston comprises an electromagnetic drive device having a coil.

In order to provide safety against damage due to a possibly excessive pressure increase caused by the leak testing device, the prestressing element provides a prestressing force which acts on the second piston in such a way that, after a predetermined pressure increase in the pressure chamber, the second piston sealed on the opening is lifted off the sealing seat on the opening and the pressure chamber can be vented to the atmosphere.

It is further preferred that the apparatus comprises a shut-off valve, which is set up for shutting off the pressure chamber with respect to the tank assembly.

Preferably, the device further comprises a control unit which is set up for determining the pressure in the pressure chamber and/or the pressure in the region of the tank assembly which is connected to the pressure chamber and determining whether a leak is present. The determination of the presence or absence of a leak can be carried out, for example, by checking the pressure rise in the closed region and/or by checking the current consumption of the electric motor of the drive for moving the first piston and/or the second piston.

Furthermore, the invention relates to a tank ventilation assembly comprising the inventive leak inspection device. The leak detection device is preferably arranged in a ventilation line which connects the atmosphere to a filter element, in particular an activated carbon filter. It is further preferred that the tank ventilation assembly comprises a pressure sensor, which is preferably arranged in the ventilation line and/or in the tank or a component connected to the tank and is set up for determining the pressure in the tank and/or the component. This makes it possible to determine the pressure change in a simple and reliable manner when checking for leaks. It is further preferred that the tank ventilation assembly comprises a control unit which is connected to the pressure sensor and which is set up to determine a leak as a function of a pressure change and/or which is connected to the drive of the leak testing device and can deduce whether a leak is present as a function of the energy consumption of the drive of the leak testing device.

Further preferably, the tank ventilation assembly comprises a shut-off valve arranged in the ventilation line between the leak check device and the filter device. Further preferably, the tank ventilation assembly comprises a tank ventilation line connecting the tank to the combustion engine and comprises a tank ventilation valve releasing and closing the connection to the combustion engine.

Drawings

Embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the drawings:

FIG. 1 shows a schematic view of a tank ventilation assembly with a leak inspection apparatus according to the present invention;

FIG. 2 shows a detail of the leak testing device of FIG. 1 in the inoperative state and

fig. 3 shows a schematic view of the leak inspection apparatus of fig. 2 in an operating state.

Detailed Description

The tank ventilation assembly 1 according to the preferred embodiment of the present invention will be described in detail with reference to fig. 1 to 3.

As can be seen from fig. 1, the tank ventilation assembly 1 comprises a tank 2 and a tank ventilation line 6 which connects the tank 2 to the internal combustion engine 100. In the tank ventilation line 6, an activated carbon filter 3 is arranged. As can be further seen from fig. 1, a tank ventilation valve 5 is arranged between the activated carbon filter 3 and the internal combustion engine 100, which releases and closes a tank ventilation line 6.

Further, a ventilation line 7 is provided, which communicates the atmosphere 16 with the carbon filter 3.

In the ventilation line 7 a leak check device 10 of the invention is arranged.

Further, a shut-off valve 8 is installed in the ventilation line 7 between the leak inspection device 10 and the activated carbon filter 3, and closes and releases the ventilation line 7.

Reference numeral 4 denotes a pressure sensor which detects the pressure in the tank ventilation assembly. As can be seen from fig. 1, pressure sensor 4 is arranged in this case in the region of ventilation line 7 between shut-off valve 8 and carbon filter 3. It should be noted, however, that the pressure sensor 4 can also be arranged on another region of the tank ventilation assembly, wherein this assembly region is bounded by the shut-off valve 8 and the ventilation valve 5 facing the tank 2. Of course, the pressure sensor 4 may also be provided on the tank 2.

The leak check device 10 can be seen in detail in fig. 2 and 3. The leak testing device 10 comprises a pressure chamber 15 into which the ventilation line 7 opens and which has a connection 17, in which the ventilation line 7 continues in the direction of the activated carbon filter 3.

Further, the leak inspection apparatus 10 includes a first piston 11 and a second piston 12. As can be seen from fig. 2, a pretensioning element 14 is arranged between the first piston 11 and the second piston 12. The pretensioning element 14 pretensions the first piston 11 against the second piston 12. Reference numeral 13 denotes an electric drive which is part of a drive for moving the first and/or

second piston

11, 12. The electric drive drives the screw 31 of the screw mechanism 30. The threaded spindle 31 engages with a threaded opening 32 formed in the first piston 11. The first piston 11 thus acts like a nut of the spindle mechanism and moves in the axial direction of the spindle when the spindle rotates.

Furthermore, a sealing seat 19 is arranged at the opening of the ventilation line 7, which connects the pressure chamber 15 to the atmosphere 16. The sealing seat 19 is released and sealed by the outwardly directed piston bottom face 12a of the second piston 12. Thereby, the communication between the pressure chamber 15 and the atmosphere 16 is released and interrupted by the second piston 12. The pressure chamber 15 is delimited by a pressure chamber housing 15 a.

As can be seen from fig. 2 and 3, the ventilation line 7 projects into the pressure chamber 15. The outlet of the ventilation line 7 is directed in the direction of the second piston 12. As shown in fig. 2 and 3, a 90-degree deflection of the delivered air is thereby obtained.

Further, a stopper 20 is provided between the first piston 11 and the second piston 12. The stop 20 comprises a first stop surface 21 directed radially inwards and a second stop surface 22 directed radially outwards. A first stop surface 21 is arranged on the first piston 11 and a second stop surface 22 is arranged on the second piston 12. In this embodiment, the two stop surfaces are circular surfaces, however, it should be noted that the stop surfaces may also be divided into a plurality of facets.

As further shown in fig. 2, a first sealing device 23 is arranged between the first piston 11 and the second piston 12, and a second sealing device 24 is arranged between the first piston 11 and the pressure chamber housing 15 a.

As can be seen from fig. 2, the second piston 12 is arranged partially in the first piston 11. Here, the second piston 12 passes through an opening 11a which is provided on the opposite side of the first piston 11 to the threaded opening 32. The first sealing device 23 seals in the opening 11a between the first piston 11 and the second piston 12.

Thus, the first piston 11 is movably arranged in the second piston 12 in the axial direction of the lead screw 31. As can be seen from fig. 2 and 3, the prestressing element 14 is arranged inside the first piston 11 and constantly exerts a prestressing force F on the second piston 12. Thereby, the second stop surface 22 is kept in contact with the first stop surface 21.

Here, the leak inspection apparatus 10 of the present invention operates as follows: the starting point is the position shown in fig. 2, in which the ventilation line 7 provides communication between the atmosphere 16 and the carbon filter 3. It should be noted here that the shut-off valve 8 can be open or closed. It should also be noted that the shut-off valve 8 can also be dispensed with entirely. In this state shown in fig. 2, the activated carbon filter 3 can therefore be flushed with fresh air.

If a leak check is now to be carried out, the electric drive 13 is driven. Thereby, the lead screw 31 rotates and the first piston 11 moves axially in the direction of arrow a via the threaded opening 32. In this case, the second piston 12 always bears with the second stop surface 22 against the first stop surface 21, since the prestressing element 14 continuously provides a prestressing force F which presses the second piston 12 against the first piston 11. The second piston 12 is thereby likewise moved axially in the direction of the arrow B. As soon as the distance C between the piston base 12a and the sealing seat 19 has been covered, the piston base 12a comes to bear against the sealing seat 19, as is shown in fig. 3. Thereby interrupting the communication between the atmosphere 16 and the pressure chamber 15.

If the shut-off valve 8 is closed, it is now opened. The electric drive 13 is operated further, so that now, as illustrated in fig. 3, only the first piston 11 is also moved axially, which is indicated by arrow a in fig. 3. In order to check for leaks, the tank ventilation valve 5 is also closed, so that, when no leaks are present, a pressure increase occurs in the pressure chamber 15 and in all regions of the tank ventilation assembly 1 which are connected to the pressure chamber 15 as a result of further movement of the first piston 11.

Furthermore, a control unit 101 is provided, which is connected to the pressure sensor 4, the shut-off valve 8, the tank ventilation valve 5 and the electric drive 13, as shown in fig. 1. The control unit 101 is set up for detecting a leak in the tank ventilation assembly 1, which is described next.

By the continuous pressure increase due to the continued movement of the first piston 11 in the direction of arrow a, the pressure in the tank ventilation assembly 1 is increased, which can be detected by the pressure sensor 4. In this case, the control unit 101 determines whether the pressure increase lies within a predetermined range, for example by comparison with stored values. Alternatively, the control unit 101 can also monitor the current consumption of the electric drive 13 or, for control purposes, both the pressure increase and the current consumption of the electric drive 13 by means of the pressure sensor 4.

If there is a leak in the tank ventilation assembly 1, the pressure in the tank ventilation assembly 1 will not rise or rise too slowly. The tank leak diagnosis can be performed in a simple manner. The leakage can also be detected or additionally checked by monitoring the current consumption of the electric drive 13.

It should be noted that it is also conceivable, for example, to close the shut-off valve 8 and to determine the pressure holding capacity of the tank ventilation assembly 1 after a pressure increase has been brought about by the leak check device 10.

Further, according to the invention, an overpressure limitation can be established in a simple manner, since the second piston 12 has a larger diameter compared to the outer diameter of the sealing seat 19. In this case, by selecting the spring force, a pressure value can be determined in the pressure chamber 15, from which the sealing seat 19 is released, whereby pressure damage on the components of the tank assembly can be avoided.

Further, according to the invention, for example, a simple solution for leak testing can also be provided in the case of very low tank levels. In this case, for example, in the case of a very compact design of the leak testing device, it may happen that the compression stroke achieved by means of the first piston 11 is not sufficient to build up a sufficient pressure increase. In this case, the shut-off valve 8 can be closed after the first pressure has increased, the first piston 11 is again returned to the position shown in fig. 3 at the stop of the second piston, after which the shut-off valve 8 is again opened and the electric drive is again moved in the direction a in order to move the first piston 11 axially. In this way, a plurality of pressure increases can be achieved in a simple manner, wherein the second piston prevents a connection to the atmosphere 16 during each stroke.

It should also be noted that instead of the spindle mechanism 3, for example, a lever assembly or a curved rail element or the like for axially moving the piston can also be used.

It should also be noted that the leak check device 10 may also be used for this purpose: the regeneration flow for regenerating carbon filter 3 can also be supported by a volume change in pressure chamber 15 via ventilation line 7.

Claims

1. Leak inspection apparatus for inspecting a tank assembly having a tank for leaks, comprising:

-a pressure chamber (15),

-a first piston (11) and a second piston (12) arranged in the pressure chamber (15),

-drive means (13) for moving the first piston (11) and/or the second piston (12),

-a ventilation line (7) opening into the pressure chamber (15), which ventilation line is in communication with the atmosphere (16),

-wherein a sealing seat (19) is formed on an access opening of the ventilation line (7) into the pressure chamber (15), wherein the access opening can be released and closed by the second piston (12),

-a pretensioning element (14) arranged between the first piston (11) and the second piston (12) for pretensioning the first piston (11) against the second piston (12),

-a stop (20) between the first piston (11) and the second piston (12), wherein the pretensioning element (14) presses the second piston (12) against the stop (20) against the first piston (11), and

-a joint (17) set up for connection with the tank assembly,

-wherein the first piston (11) is established for increasing the pressure in the pressure chamber (15) when the second piston (12) closes the access opening of the ventilation line (7) on the sealing seat (19).

2. The leak inspection device as claimed in claim 1, wherein the stop (20) has a first stop face (21) directed radially inward on the first piston (11) and a second stop face (22) directed radially outward on the second piston (12), which are set up to abut against one another.

3. The leak inspection apparatus as claimed in claim 1 or 2, wherein the drive device comprises an electric motor (13) which is set up for axially moving the first piston (11) and/or the second piston (12).

4. A leak inspection apparatus according to claim 3, further comprising a lead screw mechanism (30) which converts a rotational movement of the electric motor (13) into a linear movement of the first piston (11) and/or the second piston (12).

5. A leak inspection apparatus according to claim 3, wherein the drive means further comprises a rocking lever or paddle assembly which converts rotational motion of the motor (13) into linear motion of the first piston (11) and/or the second piston (12).

6. A leak inspection apparatus according to claim 3, wherein the drive means further comprises a curved track element which converts a rotational movement of the motor (13) into a linear movement of the first piston (11) and/or the second piston (12).

7. The leak testing device according to claim 1 or 2, wherein the pretensioning element (14) has a pretensioning force (F) which acts on the second piston (12) in such a way that the second piston (12) is lifted from the sealing seat (19) on the inlet opening of the ventilation line (7) after a predetermined pressure rise in the pressure chamber (15).

8. Leak check apparatus according to claim 1 or 2, further comprising a shut-off valve (8) which is set up for shutting off the pressure chamber (15) with respect to the tank assembly.

9. Leak inspection apparatus according to claim 1 or 2, further comprising a control unit (101) which is set up for determining the pressure in the pressure chamber (15) and/or the pressure in a region of the tank assembly which is connected to the pressure chamber (15), and for determining whether a leak is present.

10. A tank ventilation assembly comprising:

-a leak inspection apparatus according to any of the preceding claims 1 to 9, and

-a ventilation line (7) in which the leak inspection device (10) is arranged.

11. Assembly according to claim 10, further comprising a pressure sensor (4) which is arranged in the ventilation line (7) or in a component connected to the tank and is set up for determining the pressure.

12. Assembly according to claim 10 or 11, further comprising a filter device and a shut-off valve (8), wherein the shut-off valve (8) is arranged in the ventilation line (7) between the filter device and the leak check device (10).