Valve unit for an internal combustion engine and internal combustion engine

The invention relates to a valve unit for at least one of influencing and controlling a gas flow in an internal combustion engine comprising at least one valve member for modifying a cross-section of a gas flow-carrying channel through which a fluid flows and a drive train for rotatingly driving the at least one valve member. The drive train comprises an input shaft, which is drivingly coupled to a drive device in the mounted state, and at least one valve member shaft which is non-rotationally connected to the valve member. It is especially advantageous if the drive train comprises at least one phase adjuster for drivingly coupling the input shaft and the valve member shaft, a rotational position of the shafts in relation to each other being adjustable by the phase adjuster.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to German patent applications DE 10 2008 033 885.0 filed on Jul. 18, 2010; DE 10 2008 056 199.1, filed on Nov. 16, 2008, and PCT/EP2009/058929, filed on Jul. 13, 2009, all of which are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a valve unit for influencing and/or controlling a gas flow in an internal combustion engine, in particular of a motor vehicle. The invention relates also to an internal combustion engine having at least one such valve unit.

BACKGROUND

Valve units usually have a valve member by means of which a cross-section of a gas flow-conveying channel through which a fluid can flow can be changed. For this, the valve member can be actuated discontinuously to be able to adjust it between discrete switching positions. Once such discrete switching positions are reached, the valve member has to be stopped. In order to be transferred into another switching position, the valve member has to be appropriately accelerated. In case of short switching times and/or short time intervals between successive switching operations, a comparatively high amount of energy for decelerating and accelerating the valve member is necessary. A drive device which is suitable for this has a comparatively complicated structure and, accordingly, can be expensive.

Alternatively, such a valve member can also be actuated continuously. For example, the valve member rotates about an axis and runs through different switching states with each rotation. Such a valve member can be permanently driven. By varying the rotational speed, different switching frequencies or switching times can be implemented.

A valve unit of the aforementioned type can be used in a motor vehicle for adjusting the exhaust gas recirculation rate. For this purpose, the associated valve member can be arranged in a fresh air path of the internal combustion engine so that, by periodically opening and closing the cross-section through which a fluid can flow, pressure oscillations are generated or amplified by means of which the exhaust gas recirculation rate can be adjusted. By the pressure oscillations generated by means of the valve unit in the fresh air path, among other things, oscillation phases with a comparatively low pressure are generated which allow or facilitate that exhaust gas can flow over from a recirculation line into a fresh air path. Thereby, it is in particular also possible to achieve an exhaust gas recirculation on the pressure side of a charging device in a supercharged internal combustion engine.

Additionally or alternatively, such a valve unit can also be arranged in a recirculation line in order to generate or amplify pressure oscillations by periodically opening and closing the cross-section through which a fluid can flow by means of the valve member. Said pressure oscillations have oscillation phases with a relatively high pressure which allow or facilitate that the exhaust gas flows over from the recirculation line into a fresh gas path. Here too, the use in a supercharged internal combustion engine can be implemented, wherein the recirculated exhaust gas is conveyed into the high pressure side of the fresh air path.

SUMMARY

The present invention is concerned with the problem to provide for a valve unit of the aforementioned type and for an internal combustion engine equipped therewith, an advantageous embodiment which is in particular characterized in that it can be implemented in a comparatively inexpensive manner and/or that it has an improved functionality.

This problem is solved according to the invention by the subject matters of the independent claims. Advantageous embodiments are subject matter of the dependent claims.

The invention is based on the general idea to arrange in a valve unit having a permanently driven valve member, a phase adjuster in a drive train for rotatingly driving the valve member, and to arrange the phase adjuster between a rotatably driven input shaft and a valve member shaft driving the valve member in such a manner that a rotational position of the two shafts relative to each other can be adjusted depending on the requirements. Due to the variation of the rotational position of the drive train's input side formed by the input shaft relative to the drive train's output side formed by the valve member it is possible to move, within the rotational movement, the closing phases and the opening phases of the valve member forwards or backwards or, respectively, towards an early or retarded position. Furthermore, in case of a dynamic actuation of the actuator, it is possible to change the length or the circumferential portion of the opening phases and closing phases within the rotational movement.

Thus, the proposed construction allows a change of the virtually rigid coupling between input shaft and valve member, whereby it is possible also in case of a permanently driven drive train to vary the actuation of the valve member. Therefore, the valve unit as well as the internal combustion engine equipped therewith achieves an increased functionality.

According to a particular embodiment, the phase adjuster can be configured as addition gearing. Such an addition gearing is characterized in that it can superimpose an input-side second rotational movement to an input-side first rotational movement and then provides the superimposed rotational movement quasi as sum on the output side. A typical example for such an addition gearing is a planetary gearing. Accordingly, in an advantageous development, the phase adjuster can be designed as planetary gearing. Advantageously, the latter is mounted in such a manner that a sun gear of the planetary gearing is drivingly coupled with the input shaft while a planetary gear carrier carrying gears of the planetary gearing is drivingly coupled with the valve member or vice versa. The sun gear and the planetary gear carrier are drivingly coupled to each other via a non-rotating annulus gear. By means of a suitable actuator, the annulus gear can be changed with respect to its rotational position. Hereby, a rotational position of the drive gear relative to the valve member can be varied.

Particularly advantageous is an embodiment in which the drive train has an actuatable coupling which is connected on the input side in a rotationally fixed manner to an input section of the input shaft, wherein the coupling is connected in a rotationally fixed manner on the output side to an output section of the input shaft. In a coupled state, the coupling provides a rotationally fixed connection between the two sections of the input shaft and, in a decoupled state, allows rotational movements of the sections relative to each other. In other words, by means of a coupling actuatable in such a manner, the valve member can be decoupled from the drive train or can be connected thereto. Hereby, the functionality of the valve unit and the internal combustion engine can be further increased.

Further important features and advantages arise from the sub-claims, from the drawings, and from the associated description of the figures based on the drawings.

It is to be understood that the above mentioned features and the features yet to be explained hereinafter can be used not only in the respectively mentioned combination but also in other combinations or alone without departing from the context of the present invention.

DETAILED DESCRIPTION

According to theFIGS. 1-5, a valve unit1by means of which a gas flow of an internal combustion2illustrated inFIG. 6can be influenced or controlled comprises at least one valve member3. By means of the valve member3, a cross-section of a channel4through which a fluid can flow can be changed.FIGS. 1-5show a channel section which is also designated with4and which forms an integral part of the valve unit1and which can be mounted into a corresponding channel of the internal combustion engine2. The internal combustion engine2is preferably arranged in a motor vehicle.

The valve unit1comprises a drive train5by means of which the at least one valve member3can be rotatably driven. In doing so, the valve member3rotates about a rotational axis6. Said drive train5has, e.g., a drive wheel7which is connected to an input shaft8in a rotationally fixed manner. In the mounted state, said drive wheel7is preferably permanently coupled with a drive device31, which is indicated only inFIG. 6, in such a manner that the drive device31drives the drive wheel7in a rotatable manner. Then, the drive wheel7rotates also about the rotational axis6. This drive device31can principally involve any drive. For example, an electric motor can be provided. The drive coupling which is suitably also designated with31, is indicated in the example of theFIGS. 1 to 5by a drive belt9between the respective drive device and the drive wheel7. However, other drive couplings31are principally also conceivable such as, for example, V-belts, chains, gear wheels and the like. Preferably, the drive device31is not an additional drive but a device which is present in the internal combustion engine2anyway. For example, this involves a shaft which is driven by the internal combustion engine during the operation of the same such as, for example, a crankshaft or a camshaft. Hereby, it is possible to implement in particular a permanent drive of the drive wheel7can be implemented as soon as the internal combustion engine2is in operation. Furthermore, such a drive coupling31between drive wheel7and internal combustion engine2results in that the drive wheel7is always driven at a speed proportional to the speed of the internal combustion engine2. Moreover, the drive train5has at least one valve member shaft10which is connected to the valve member3in a rotationally fixed manner.

Further, the drive train5has at least one phase adjuster11which, in the shown preferred example, is configured as planetary gearing11. However, other mechanically working addition drives are principally also advantageous. Principally, a hydraulically or pneumatically working phase adjuster can also be used. According toFIG. 7, the preferred planetary gearing11comprises in a usual design, one sun gear12, a plurality of planetary gears13, one planetary gear carrier14and one annulus gear15. The planetary gears13are rotatably mounted at the planetary gear carrier14and engage with the centrally arranged sun gear12. Moreover, the planetary gears13engage with the annulus gear15. According to theFIGS. 1-5, the planetary gearing11or any other addition gearing11or any other phase adjuster11serves for adjusting a rotational position of the input shaft8relative to the valve member shaft10. For this purpose, the respective phase adjuster11, here the planetary gearing11, establishes a drive coupling between the input shaft8and the valve member shaft10. For this, the sun gear12of the planetary gearing11is connected in a rotatably fixed manner to the one shaft, for example to the input shaft8, while the planetary gear carrier14is connected in a rotatably fixed manner to the other shaft, thus, for example, to the valve member shaft10. It is obvious that a reversed configuration can principally also be implemented, wherein the sun gear12is connected in a rotatably fixed manner to the valve member shaft10, while the planetary gear carrier14is connected in a rotatably fixed manner to the input shaft8. With the annulus gear15standing still, thus, with the annulus gear15being fixed relative to the environment of the drive train5, the valve member shaft10and the input shaft8are drivingly and forcibly coupled to each other. However, by changing the absolute rotational position of the annulus gear15, the relative rotational position between the shafts8,10coupled to each other via the planetary gearing11can be varied or, respectively, adjusted.FIG. 7shows a greatly simplified actuator16by means of which the annulus gear15can be actuated in a rotatable manner. With said actuator16, the annulus gear can carry out rotations about the rotational axis6which are in particular angularly limited.

FIGS. 2,4and5show embodiments in which two valve members3are provided. In the exemplary embodiments shown in theFIGS. 2 and 4, the latter are rotationally fixedly connected to the same valve member shaft10. In the example, the two valve members3are rotated relative to each other, thus, are arranged in different rotational positions on the common valve member shaft10. Here, the two valve members3are arranged in two separate channels4or channel sections4. In the embodiments of theFIGS. 2,4and5, the two channel sections4form an integrally producible structural unit.

In the embodiments ofFIGS. 3-5, the drive train5is also equipped with an actuatable coupling17. Said coupling17which, for example, can be actuated hydraulically or electrically or pneumatically is rotationally fixedly connected on the input side to an input section18of the input shaft8. On the output side, the coupling17is rotationally fixedly connected to an output section19of the input shaft8. Further, the coupling17can be switched between a coupled state and a decoupled state. In the coupled state, the two shaft sections18,19are connected to each other in a rotationally fixed manner. In the decoupled state, the two shaft sections18,19can be rotated relative to each other. In the decoupled state, the coupling17thus allows a relative rotational movement between the sections18,19of the input shaft8. Since the coupling17is integrated in the input shaft8, the coupling is located within the drive train5between the drive wheel7and the phase adjuster11or, respectively, the planetary gearing11. It is principally also conceivable to integrate the coupling17between the phase adjuster11or the planetary gearing11and the valve member3into the valve member shaft10.

Thus, by means of the coupling17, the rotational movement of the valve members3can be stopped even if the drive wheel7is still permanently driven. For example, conceivable for the internal combustion engine2are operational states in which the valve unit1or, respectively, a periodical opening and blocking of the respective channel4is not desired. Furthermore, errors can occur. The possibility of decoupling the respective valve member3from the respective drive device or, respectively, from the drive wheel7then provides an emergency function for the internal combustion engine2.

According to theFIGS. 1-5, the valve unit1can additionally be equipped with a sensor20by means of which the absolute rotational position of the respective valve member3or the two valve members3can be determined.

In the embodiment shown inFIG. 5as well as in the embodiments of theFIGS. 2 and 4, two valve members3are provided to vary or control the cross-sections, through which a fluid can flow, in two separate channels or channel sections4. While in the embodiments of theFIGS. 2 and 4, the two valve members3are rotationally fixedly connected to a common valve member shaft10, the drive train5of the embodiment shown inFIG. 5has two separate valve member shafts10and10′, each of which is rotationally fixedly connected to one of the valve members3. Furthermore, the embodiment ofFIG. 5is equipped with an additional or further phase adjuster11′ by means of which the two valve member shafts10,10′ are drivingly coupled to each other. The further phase adjuster11′ can again be configured as planetary gearing11′ or as any other suitable addition gearing11′. Said further or second planetary gearing11′ has principally the same structure as the previously described first planetary gearing11. Here, the sun gear12of the second planetary gearing11′ is rotationally fixedly connected to the one valve member shaft3while the planetary gear carrier14is rotationally fixedly connected to the other valve member shaft3. Here too, the annulus gear15can be rotationally actuated by means of a suitable actuator in order to be able to fix or adjust or, respectively, vary the relative rotational position of the two valve members3with respect to each other. Through this configuration it is possible to change the quasi synchronously rotating valve members3with respect to their relative rotational position.

Advantageously, the second planetary gearing11is configured in such a manner that, when the annulus gear15stands still, it transmits the rotational movement of the one valve member shaft10without speed transformation, thus 1:1, to the other valve member shaft10′. Independent of this, the previously described or first planetary gearing11can couple the two shafts coupled to the planetary gearing, namely the input shaft8and the valve member shaft10, to each other without speed transmission, thus without speed change. Alternatively, a gear ratio or a gear reduction is also conceivable for this planetary gearing11.

According toFIG. 7, a reset spring21can be allocated to the respective phase adjuster11or addition gearing11or, respectively, planetary gearing11, which spring is illustrated inFIG. 7merely in a cursory manner and which drives the two shafts8,10,10′ into a relative initial position. In the example, said reset spring21thus serves for driving the annulus gear15into an initial position. For this purpose, the reset spring21engages with the annulus gear15. Alternatively, the reset spring21can also engage with the actuator16. For transmitting a torque into the annulus gear15in order to rotate the annulus gear15about the rotational axis6, an actuating pin22can be attached to the annulus gear15, which pin projects from the annulus gear15in the shown examples. In the embodiments of theFIGS. 1-5, the respective planetary gearing11or, respectively,11′ is equipped on its annulus gear15in each case with two such actuating pins22. The one actuating pin22serves, for example, for coupling the respective planetary gearing11,11′ to the actuator16, while the other actuating pin22then advantageously serves for coupling the respective planetary gear11,11′ to the reset spring21.

According toFIG. 6, the internal combustion engine2comprises an engine block23, a fresh air path24for supplying fresh air to the engine block23and an exhaust gas path25for discharging exhaust gases from the engine block23. Furthermore, a recirculation line26is provided here which allows to recirculate exhaust gas from the exhaust gas path25to the fresh air path24. It is obvious that said recirculation line26can also run, at least partially, within the engine block23.

In the example, the internal combustion engine2is also equipped with a charging device27. As an example, this can involve an exhaust gas turbocharger, the turbine28of which is arranged in the exhaust gas path25and is rotationally fixedly connected via a shaft29to a compressor30which is arranged in the fresh air path24. It is particularly useful to connect the recirculation line26on the exhaust gas side upstream of the turbine28to the exhaust gas path25in order to be able to provide a pressure level as high as possible in the exhaust gas to be recirculated. Furthermore, it is useful to connect the recirculation line26downstream of the compressor30to the fresh air path24to prevent contamination, for example by soot, of the compressor30.

The internal combustion engine2can have at least one valve unit1of the above described design. For example, such a valve unit1is mounted in the fresh air path24. In the region in which the valve unit1is integrated, the fresh air path24has a channel4which is suitable for this. Alternatively, such a valve unit1can be mounted in the recirculation line26which, at the mounting location of the valve unit1, is configured as channel4. Furthermore, also conceivable is an embodiment in which one such valve unit1can be arranged in each case in the fresh air path24as well as in the recirculation line26. In any case, the respective valve unit1is present in addition to the gas exchange valves of the internal combustion engine2or the engine block23. The respective valve unit1is arranged here in the fresh air path24or the recirculation line26upstream of the gas exchange valves.

The aforementioned drive device31for driving the drive wheel7can be formed—as illustrated—by a component driven during the operation of the internal combustion engine2, for example by the engine block23. For example, this involves a crankshaft or a camshaft. It is also possible to implement a coupling with a toothed belt driven by the crankshaft or with a V-belt or the like also driven by the crankshaft. A corresponding drive coupling31between the drive train5of the respective valve unit1with the engine block23is indicated inFIG. 6by a double arrow with a broken line and designated with31. In particular, the respectively selected drive device31is configured for permanently driving the drive wheel7during the operation of the internal combustion engine2. The drive device, which can also be designated with31, preferably forms an integral part of the internal combustion engine2or the engine block23. Furthermore, the respective drive device31is suitably configured for driving the drive wheel7at a speed which is proportional to the drive speed of the crankshaft of the internal combustion engine2. By synchronizing the drive train5of the valve unit1with the speed of the internal combustion engine2, a clear allocation to the gas exchange processes in the individual cylinders of the internal combustion engine2takes place. If the crankshaft angle is known, it is also possible to specifically match the switching processes of the valve unit1with the gas exchange processes.

The valve unit1preferably serves for adjusting an exhaust gas rate of the exhaust gas recirculation system. For example, by means of the valve unit1arranged in the fresh air path24, pressure oscillations can be generated in the fresh air, which oscillations reach comparatively low pressures in the region of their negative oscillation amplitudes even if the valve unit1—as in the example shown in FIG.6—is arranged, with respect to the charging device27, on the pressure side of the fresh air path24. In particular by utilizing fluid dynamic effects it is possible in a relatively simple manner to generate or amplify periodically repeating pressure regions within the pressure oscillation, which pressure regions lie below the pressure of the exhaust gas to be recirculated in the recirculation line26. By controlling or utilizing the pressure oscillations in the fresh air path24it is thus possible to control or adjust the exhaust gas recirculation rate.

In contrast to that, the valve unit1arranged in the recirculation line26can be utilized for generating or amplifying pressure oscillations in such a manner that pressures occur in the region of positive oscillation amplitudes, which pressures lie above the pressure of the fresh air in the fresh air path24. This also applies in particular if the recirculation line26—as in the example shown in FIG.6—is connected to the pressure side of the fresh air path24. Thus, by controlling the pressure oscillations in the recirculation line26, the exhaust gas recirculation rate can be adjusted.

The above described two forms of utilization of the valve unit1in an internal combustion engine2can be implemented alternatively as well as cumulatively. Principally, other mounting situations for the valve unit1are also conceivable. For example, such a valve unit1can also be arranged in the exhaust gas path25downstream of the connection point between recirculation line26and exhaust gas path25so as to bring the pressure in the exhaust gas to an increased pressure level by periodically back-pressuring.

Due to the permanent or forced speed coupling between crankshaft and the at least one valve member3, the gas exchange processes and the opening movements or, respectively, closing movements of the valve member3work synchronously. For example, to be able to vary the exhaust gas recirculation quantity at a certain operating point of the internal combustion engine, a time shift between the gas exchange processes and the closing processes or, respectively, opening processes of the respective valve member3can be implemented by means of the mentioned actuator16. In these settings, the actuator16is “statically” actuated, that is, a certain relative rotational position between the shafts8,10coupled with the respective phase adjuster or planetary gearing11,11′ is set and maintained at least temporarily. It is principally also possible to actuate the actuator16dynamically, whereby it is in particular also possible to vary the opening phases or closing phases of the respective valve member3. This can also be utilized for changing the exhaust gas recirculation rate.

With respect to the associated valve member3, the respective valve member shaft10can be a separate component which is rotationally fixedly connected in a suitable manner to the associated valve member3. It is also possible to structurally integrate the respective valve member shaft10into the associated valve member3. In the embodiments shown herein, the valve member3is configured in each case as flap valve, in particular as butterfly valve. It has a rectangular cross-section. Other cross-sections for the flap-shaped valve member3are also conceivable. Alternatively, the valve member can also be configured as rotary slide valve or the like.