WO2018192755A1

WO2018192755A1 - Tank ventilation device

Info

Publication number: WO2018192755A1
Application number: PCT/EP2018/057776
Authority: WO
Inventors: Andreas Posselt; Bjoern Noack
Original assignee: Robert Bosch Gmbh
Priority date: 2017-04-20
Filing date: 2018-03-27
Publication date: 2018-10-25
Also published as: DE102017206645A1

Abstract

The invention relates to a tank ventilation device (1) for ventilating a tank (6), comprising a plurality of vent valves (2) which can be actuated by at least one cam (3), all cams (3) being rotatable about a common axis of rotation (100).

Description

description

title

Tank deaeration device prior art

The present invention relates to a tank ventilation device for venting a tank. Moreover, the invention relates to an internal combustion engine comprising a tank and a corresponding tank ventilation device.

Tank venting systems are known from the prior art. These have actively switched electromechanical tank ventilation valves. To prevent the hydrocarbons from escaping from the tank into the atmosphere, an activated carbon filter is provided which captures the fuel vapors from the tank. A partial flow of an intake air of an internal combustion engine is passed through this filter, so that the fuel vapors of the activated carbon filter are passed into the combustion chamber of the internal combustion engine, where they are burned as part of the air-fuel mixture. The tank vent valve meters this air flow according to the operating condition of the engine. The

Control of known tank ventilation valves is not proportional, but discrete PWM signals. For turbo engines also two parallel discharge points are provided, each with its own

Tank vent valve is provided. In addition, a Venturi nozzle can be used, which is operated with air, which is compressed by a turbocharger, to increase the mass flow of air when purging the activated carbon filter.

With latest developments, in particular by downsizing and

Hybridization, the pressure potential to the suction pipe and / or the duration in which this reduced differential pressure is applied, reduced. This pushes conventional tank venting systems to their limits. From the prior art are also cylinder-individual

Tank vent valves are known, which represent an approach to precise and / or to the metering of the hydrocarbons from the activated carbon filter, which are included in the purge mass flow through the activated carbon filter

equalize. As a result, a quiet engine running is achieved, while the theoretical Spülmassen be optimally utilized.

In the prior art, it is known that the tank vent valves are opened in synchronism with intake valves of the engine, which optimizes the

Metering the mass flows to the engine cylinders causes. The control of the

Flushing mass flow takes place via an adjustable phase offset.

However, the arrangement of many tank ventilation valves as a consequence of the aspired cylinder-individual metering locally close to the engine inlet valve due to space reasons very difficult. In particular, the assembly costs are multiplied by such an arrangement and at the same time a large variety of ECU pins required.

Disclosure of the invention

The tank ventilation device according to the invention allows a flexibilization of the required installation space, wherein at the same time cost-reduced and the use of a common drive, the control unit is potentially relieved of pins. In particular, the tank venting device according to the present invention enables modularization of a plurality of discrete, cylinder-individual tank venting valves. In addition, the

Tank ventilation device a central drive of the valve groups by different drive options. The tank venting device according to the invention for venting a tank comprises a plurality of venting valves. It is provided that the vent valves of at least one cam can be actuated. All cams are rotatable about a common axis of rotation. Particularly advantageously, the number of vent valves corresponds to a number of

Cylinders of an internal combustion engine, whose tank the

Tank venting device has. By the at least one cam are the vent valves mechanically actuated. The actuation takes place either directly via the cams and / or via an additional lever mechanism. The rotation of the cam about the common axis of rotation advantageously takes place synchronously with a rotation of a camshaft of an associated one

Internal combustion engine, wherein with said camshaft intake valves of

Internal combustion engine can be driven.

The dependent claims have preferred developments of the invention to the content.

It is preferably provided that the at least one cam extends radially on a shaft and / or axially on a disk. Due to the axial arrangement on a disc, a space requirement is minimized. This is particularly advantageous when a maximum of four cylinders are present, whereby a maximum of four vent valves must be controlled by the at least one cam. In this case, it is provided that only one engine inlet valve is always open, whereby only one vent valve is always open. Thus, the presence of a single cam is sufficient. The shaft and / or the disc are advantageously for rotation with a

Camshaft of the internal combustion engine coupled. The camshaft of the

Internal combustion engine is particularly advantageous for controlling

Intake valves of the cylinders of the internal combustion engine. The coupling is advantageously carried out mechanically directly, in particular via a transmission and / or via a belt drive and / or via a chain drive. Thus, a

Rotation of the at least one cam about the common axis of rotation analogous to a rotation of the camshaft, whereby it can be ensured that the vent valves are always opened synchronously and / or in a fixed temporal relationship to the intake valves of the internal combustion engine.

In an alternative embodiment, it is particularly advantageously provided that the shaft and / or disc can be rotated by a drive motor. Of the

Drive motor is in particular an electric drive motor. Particularly advantageous is the drive motor is an electrically commutated DC motor

(BLDC). The drive motor is controlled in particular such that the shaft and / or disc in synchronism with a rotation of a camshaft of the

Internal combustion engine for controlling the intake valves rotates. In addition, by the use of the drive motor, a phase offset of the opening of the tank vent valves relative to the opening of the intake valves of the engine can be realized. This can be achieved by simply driving the drive motor.

The at least one cam is particularly advantageously coupled via a phase splitter with the shaft and / or the disc. This is particularly advantageous if the disc and / or shaft mechanically directly with the

Camshaft of the internal combustion engine is coupled. In this case, a phase shift between the opening of the

Implement intake valve and the associated vent valve. Advantageously, the tank ventilation device has a control unit. The

Control unit is set up in particular for delaying the rotation about the common axis of rotation when at least one venting valve is opened. In particular, it is provided that the control unit together with the

Drive motor is provided. Thus, the controller may drive the drive motor such that the rotation of the at least one cam about the common axis of rotation is then delayed when a tank vent valve is opened by the cam. Thus, the cam can be spread virtually, so that an opening period of the tank ventilation valve is extended. In order to establish synchronicity of the rotation of the at least one cam about the common axis of rotation with the rotation of the camshaft, it is particularly advantageous that said rotation is accelerated in such a position in which none of the tank-venting valves is opened by the at least one cam. By a relative ratio of acceleration and deceleration to each other can be a ratio between open

Set valve position and closed valve position of tank vent valves.

In a preferred embodiment, the tank ventilation device comprises at least one activated carbon element. The activated carbon element is connectable to an interior of the tank for fluid communication and thus can evaporate

Pick up hydrocarbons from the tank. This will prevent an in the fluid deposited in the tank evaporates, thus deflating the tank over time. At the same time it is provided that each vent valve for adjusting a mass flow, in particular an air mass flow, through the

Activated carbon element is formed. In particular, can be about each

Vent valve realize a mass flow that leads through the activated carbon element to each cylinder of the engine. The in the

Activated carbon element absorbed gases can thus be rinsed and transported to the cylinder, whereby a burning of the gases takes place. This leads to efficient use of the arranged inside the tank

Fuel.

It is preferably provided that in at least one position of the rotation of the at least one cam about the common axis of rotation all

Bleed valves are closed. If only a single cam is present, then it is preferably provided that in said position of the cam between two

Bleed valves remain without operating a bleed valve. If there are several cams, it is envisaged that all these cams remain between two vent valves without actuating one of the venting valves. Thus, the at least one cam is limited in its length. Nevertheless, the virtual spread described above can be used for a long time

Implement opening times of the tank venting valve.

The invention also relates to an internal combustion engine. Of the

Internal combustion engine comprises a tank for fuel of the internal combustion engine and a tank ventilation device as described above. The

Tank deaeration device is used to vent the tank. It is provided that each cylinder of the engine, a vent valve of the

Tank ventilation device is assigned. This means that each cylinder can be supplied with an adjustable mass flow through the associated venting valve, wherein said mass flow through an activated carbon element, in particular a

Activated carbon element as described above, runs. The mass flow is in particular part of an intake mass flow, which is supplied to the cylinder for combustion. Thus, the mass flow can be adjusted individually for each cylinder, so that a motor running of the internal combustion engine can be optimized. For this purpose, in particular by a different setting of the previously described virtual spread of the at least one cam for the different air vents individually tune the

Mass flow for the respective cylinder allows.

The internal combustion engine has, in particular, a camshaft for actuating intake valves of the cylinders of the internal combustion engine. It is provided that the rotation of the at least one cam to the

common axis of rotation is coupled with a rotation of the camshaft. Such a coupling can be effected in particular mechanically, in particular by means of a transmission, a belt drive, a chain drive or the like, or alternatively electrically by an angle sensor on the camshaft and an electric drive for rotating the at least one cam about the camshaft

Axis of rotation. Thus, the mass flow for each cylinder can be optimally adjusted, since it can be ensured in particular that each

Bleed valve is only open when the inlet valve of the associated cylinder is open.

Brief description of the drawings

Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings. In the drawings:

Figure 1 is a schematic view of an internal combustion engine with a

Tank ventilation device according to a first embodiment of the invention, and

Figure 2 is a schematic view of an internal combustion engine with a

Tank ventilation device according to a second

Embodiment of the invention.

Embodiments of the invention

FIG. 1 schematically shows an internal combustion engine 10, comprising a plurality of cylinders 12 and a tank 6. Fuel for operating the cylinders 12 is present in the tank 6. In addition, the internal combustion engine 10 includes a tank ventilation device 1 according to a first embodiment of the invention. The tank ventilation device 1 comprises three vent valves 2, wherein each vent valve 2 is associated with a cylinder 12 of the internal combustion engine 10. In particular, it is provided that a mass flow 200 to each one of the cylinder 12 can be controlled by each vent valve 2. The mass flow

200 extends from an activated carbon element, in particular an activated carbon filter, via a respective vent valve 2 to an intake tract 14 of the

Internal combustion engine 10, wherein each one of the mass flows is assigned directly to one of the cylinder 12.

The activated carbon element 9 is used to capture hydrocarbon gases, which arise when the fuel evaporates within the tank 6. In order to avoid saturation of the activated carbon element 9 and at the same time to be able to continue to use the trapped fuel, the activated carbon element 9 is purged by the mass flows 200. This means that the fuel taken up by the activated carbon element 9 flows through the mass flows 200 to the cylinders 12 of the internal combustion engine 10 is supplied, whereby the fuel is burned. To optimally adjust an engine run of the internal combustion engine 10, it is provided that each cylinder 12 is assigned its own vent valve 2, so that each cylinder 12 an individual

Mass flow 200 can be supplied. In this way, the engine operation of the internal combustion engine 10 can be optimized.

By the tank vent valves 2 thus each cylinder 12 and an air-fuel mixture can be supplied in addition to a general intake air. For an optimal

To enable setting of this mixture, all the vent valves 2 are controlled mechanically via a shaft 4, the shaft 4 each having a cam 3 per vent valve 2. The cams 3 thus rotate about a common axis of rotation 100, which corresponds to the shaft 4. The cams 3 are particularly advantageously connected to the shaft 4 via phase dividers (not shown).

The shaft 4 is driven by a direct coupling to a camshaft 1 1 of the internal combustion engine 10. The camshaft 1 1 is used to control not shown intake valves of the internal combustion engine 10. In particular, it is advantageous if a cylinder 12 associated with the inlet valve and Bleed valve 2 are open at the same time. The mechanical coupling of camshaft 1 1 and shaft 4 takes place in particular via a gear 13, although other power transmission mechanisms can be used.

Through the phase divider, a phase offset between opening of an intake valve of a cylinder 12 and opening of the vent valve 2 of the cylinder 12 can be adjusted. In particular, the mass flow 200 can be optimized in this way for each individual cylinder 12, since each cam 3 is individually adjustable and thus leads to an individual opening time of the respective associated venting valve 2. Therefore, the leaves

Reassemble tank ventilation device 1 simply and with little effort.

Particularly advantageously, a lever mechanism is arranged between the cams 3 and the vent valves 2. Thus, a stroke of the vent valves 2 can be adjusted, in particular also vary.

Figure 2 shows schematically an internal combustion engine 10 with a

Tank ventilation module 1 according to a second embodiment of the

Invention. The remaining components of the internal combustion engine 10 are preferably identical as in the first embodiment. A difference is only in the tank ventilation device 1. For reasons of clarity, the tank 6 and the activated carbon element 9 is not shown in Figure 2, these components are mounted analogously to the first embodiment.

In the second embodiment, only a single cam 3 is present. This cam 3 is arranged axially on a disc 5, wherein the disc 5 and thus the cam 3 is rotatable about an axis of rotation 100. The cam 3 in turn serves to control the vent valves 2, again three vent valves 2 are provided, so that each cylinder 12 of the engine 10 is associated with exactly one vent valve 2 to adjust an individual mass flow 200 to each cylinder 12.

Another difference from the first embodiment is the drive of the rotation of the at least one cam 3 about the rotation axis 100. Thus, in the second embodiment, a drive motor 7, in particular an electrically commutated DC motor, is present. This one is from one Control unit 8 activated. On a phase splitter as in the first

Embodiment preferred may be provided in the second

Embodiment advantageously be waived. Again, the at least one cam 3 is rotated about the cam

Rotation axis 100 in synchronism with a rotational speed of the camshaft 1 1 (see Figure 1) of the internal combustion engine 10. In particular, is not shown

Angle sensor present, which picks up a rotation of the camshaft 1 1 and outputs corresponding signals to the control unit 8. The control unit 8 can thus drive the drive motor 7 to the disc 5 synchronously to the

Camshaft 1 1 to rotate. Likewise, the provision of a phase offset between the opening of the inlet valves of the cylinders 12 and the venting valves 2 is made possible by a corresponding control of the drive motor 7.

It is preferably provided that the disc 5 can remain in a position in which none of the vent valves 2 is actuated by the cam 3. Thus, all the vent valves 2, in particular completely closed. A

Expansion of the cam 3 in the circumferential direction of the disc 5 is thus limited. Because such training becomes a limitation at the maximum

Rinsing mass of the respective mass flow 200 may, it is preferably provided that the control unit 8 is designed for virtual stretching of the cam 3 by appropriate driving of the drive motor 7. The virtual stretching is carried out in particular such that in such a position of the disc 5, in which the cam 3 opens one of the vent valves 2, the rotation of the disc 5 is delayed. Thus, the period in which the vent valve 2 is opened by driving through the cam 3 is extended. In order to ensure a synchronous rotation of the disc 5 with the camshaft 1 1 continues to be particularly advantageous also provided that in such a position of the disc 5, in which by the cam 3 none of

Bleed valves 2 is actuated, the rotation of the disc 5 is accelerated. Thus, the total average rotational speed of the disc 5 is the same as the rotational speed of the camshaft 1 1. At the same time, however, the each cylinder 12 supplied amount of the respective mass flow 200 is individually adjustable. The first embodiment described above may instead of the

described direct mechanical Koppeins of shaft 4 and camshaft 1 1 via the gear 13 and the second embodiment

have described drive motor 7. The same applies vice versa for the second embodiment that the described in the first embodiment direct mechanical coupling to the camshaft 1 1 may have. In this case, the disc 5, in particular by a transmission, would be directly coupled to the camshaft 11.

In summary, the following advantages of the invention result in particular:

Modularization of several discrete, cylinder-individual

Tank vent valves

central drive of the mechanical valve groups

• mechanical cam with hard coupling to the motor and preferably mechanical phase adjustment, or

• electric drive, in particular BLDC, to realize a

Phase shift and event length variation

Claims

claims

1 . A tank venting device (1) for ventilating a tank (6) comprising a plurality of venting valves (2), the venting valves (2) being operable by at least one cam (3), and wherein all the cams (3) are mounted around a common axis of rotation (100) are rotatable.

2. tank ventilation device (1) according to claim 1, characterized in that the at least one cam (3) radially on a shaft (4) and / or axially on a disc (5) is arranged.

3. tank ventilation device (1) according to claim 2, characterized in that the shaft (4) and / or disc (5) to a coupling with a camshaft (1 1) of an internal combustion engine (10) is formed.

4. tank ventilation device (1) according to claim 2, characterized in that the shaft (4) and / or disc (5) by a drive motor (7) is rotatable, wherein the drive motor (7) is in particular an electrically commutated DC motor.

5. tank ventilation device (1) according to one of claims 2 to 4, characterized in that the at least one cam (3) via a

Phase divider with the shaft (4) and / or disc (5) is coupled.

6. tank ventilation device (1) according to any one of the preceding claims, characterized by a control device (8) arranged for delaying the rotation of the at least one cam (3) about the common

Rotation axis (100) when at least one vent valve (2) is open.

7. tank ventilation device (1) according to any one of the preceding claims, characterized by at least one activated carbon element (9) which is connectable to an internal volume of the tank (6) for fluid communication, each vent valve (2) for adjusting a mass flow, in particular an air mass flow, is formed by the activated carbon element (9).

8. tank ventilation device (1) according to any one of the preceding claims, characterized in that in at least one position of the rotation of the at least one cam (3) about the common axis of rotation (100) all the vent valves (2) are closed.

9. Internal combustion engine (10) comprising a tank (6) for fuel of

Internal combustion engine (10) and a tank ventilation device (1) according to one of the preceding claims for venting the tank (6), wherein each cylinder (12) of the internal combustion engine (10) is associated with a vent valve (2) of the tank ventilation device (1).

10. internal combustion engine (10) according to claim 9, characterized in that the rotation of the at least one cam (3) about the common

Rotation axis (100) with a rotation of a camshaft (1 1) of the internal combustion engine (10) for driving intake valves of the cylinder (12) is coupled.