Abstract:
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.

Description:
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&#39;s input side formed by the input shaft relative to the drive train&#39;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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in the following description in more detail, wherein identical reference numbers refer to identical, or similar, or functionally identical components. 
       In the figures, schematically: 
         FIGS. 1-5  each show a greatly simplified, basic perspective view of a valve unit in different embodiments, 
         FIG. 6  shows a greatly simplified circuit diagram-like basic illustration of an internal combustion engine having at least one such valve unit, 
         FIG. 7  shows a greatly simplified sectional view of a planetary gearing. 
     
    
    
     DETAILED DESCRIPTION 
     According to the  FIGS. 1-5 , a valve unit  1  by means of which a gas flow of an internal combustion  2  illustrated in  FIG. 6  can be influenced or controlled comprises at least one valve member  3 . By means of the valve member  3 , a cross-section of a channel  4  through which a fluid can flow can be changed.  FIGS. 1-5  show a channel section which is also designated with  4  and which forms an integral part of the valve unit  1  and which can be mounted into a corresponding channel of the internal combustion engine  2 . The internal combustion engine  2  is preferably arranged in a motor vehicle. 
     The valve unit  1  comprises a drive train  5  by means of which the at least one valve member  3  can be rotatably driven. In doing so, the valve member  3  rotates about a rotational axis  6 . Said drive train  5  has, e.g., a drive wheel  7  which is connected to an input shaft  8  in a rotationally fixed manner. In the mounted state, said drive wheel  7  is preferably permanently coupled with a drive device  31 , which is indicated only in  FIG. 6 , in such a manner that the drive device  31  drives the drive wheel  7  in a rotatable manner. Then, the drive wheel  7  rotates also about the rotational axis  6 . This drive device  31  can principally involve any drive. For example, an electric motor can be provided. The drive coupling which is suitably also designated with  31 , is indicated in the example of the  FIGS. 1 to 5  by a drive belt  9  between the respective drive device and the drive wheel  7 . However, other drive couplings  31  are principally also conceivable such as, for example, V-belts, chains, gear wheels and the like. Preferably, the drive device  31  is not an additional drive but a device which is present in the internal combustion engine  2  anyway. 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 wheel  7  can be implemented as soon as the internal combustion engine  2  is in operation. Furthermore, such a drive coupling  31  between drive wheel  7  and internal combustion engine  2  results in that the drive wheel  7  is always driven at a speed proportional to the speed of the internal combustion engine  2 . Moreover, the drive train  5  has at least one valve member shaft  10  which is connected to the valve member  3  in a rotationally fixed manner. 
     Further, the drive train  5  has at least one phase adjuster  11  which, in the shown preferred example, is configured as planetary gearing  11 . However, other mechanically working addition drives are principally also advantageous. Principally, a hydraulically or pneumatically working phase adjuster can also be used. According to  FIG. 7 , the preferred planetary gearing  11  comprises in a usual design, one sun gear  12 , a plurality of planetary gears  13 , one planetary gear carrier  14  and one annulus gear  15 . The planetary gears  13  are rotatably mounted at the planetary gear carrier  14  and engage with the centrally arranged sun gear  12 . Moreover, the planetary gears  13  engage with the annulus gear  15 . According to the  FIGS. 1-5 , the planetary gearing  11  or any other addition gearing  11  or any other phase adjuster  11  serves for adjusting a rotational position of the input shaft  8  relative to the valve member shaft  10 . For this purpose, the respective phase adjuster  11 , here the planetary gearing  11 , establishes a drive coupling between the input shaft  8  and the valve member shaft  10 . For this, the sun gear  12  of the planetary gearing  11  is connected in a rotatably fixed manner to the one shaft, for example to the input shaft  8 , while the planetary gear carrier  14  is connected in a rotatably fixed manner to the other shaft, thus, for example, to the valve member shaft  10 . It is obvious that a reversed configuration can principally also be implemented, wherein the sun gear  12  is connected in a rotatably fixed manner to the valve member shaft  10 , while the planetary gear carrier  14  is connected in a rotatably fixed manner to the input shaft  8 . With the annulus gear  15  standing still, thus, with the annulus gear  15  being fixed relative to the environment of the drive train  5 , the valve member shaft  10  and the input shaft  8  are drivingly and forcibly coupled to each other. However, by changing the absolute rotational position of the annulus gear  15 , the relative rotational position between the shafts  8 ,  10  coupled to each other via the planetary gearing  11  can be varied or, respectively, adjusted.  FIG. 7  shows a greatly simplified actuator  16  by means of which the annulus gear  15  can be actuated in a rotatable manner. With said actuator  16 , the annulus gear can carry out rotations about the rotational axis  6  which are in particular angularly limited. 
       FIGS. 2 ,  4  and  5  show embodiments in which two valve members  3  are provided. In the exemplary embodiments shown in the  FIGS. 2 and 4 , the latter are rotationally fixedly connected to the same valve member shaft  10 . In the example, the two valve members  3  are rotated relative to each other, thus, are arranged in different rotational positions on the common valve member shaft  10 . Here, the two valve members  3  are arranged in two separate channels  4  or channel sections  4 . In the embodiments of the  FIGS. 2 ,  4  and  5 , the two channel sections  4  form an integrally producible structural unit. 
     In the embodiments of  FIGS. 3-5 , the drive train  5  is also equipped with an actuatable coupling  17 . Said coupling  17  which, for example, can be actuated hydraulically or electrically or pneumatically is rotationally fixedly connected on the input side to an input section  18  of the input shaft  8 . On the output side, the coupling  17  is rotationally fixedly connected to an output section  19  of the input shaft  8 . Further, the coupling  17  can be switched between a coupled state and a decoupled state. In the coupled state, the two shaft sections  18 ,  19  are connected to each other in a rotationally fixed manner. In the decoupled state, the two shaft sections  18 ,  19  can be rotated relative to each other. In the decoupled state, the coupling  17  thus allows a relative rotational movement between the sections  18 ,  19  of the input shaft  8 . Since the coupling  17  is integrated in the input shaft  8 , the coupling is located within the drive train  5  between the drive wheel  7  and the phase adjuster  11  or, respectively, the planetary gearing  11 . It is principally also conceivable to integrate the coupling  17  between the phase adjuster  11  or the planetary gearing  11  and the valve member  3  into the valve member shaft  10 . 
     Thus, by means of the coupling  17 , the rotational movement of the valve members  3  can be stopped even if the drive wheel  7  is still permanently driven. For example, conceivable for the internal combustion engine  2  are operational states in which the valve unit  1  or, respectively, a periodical opening and blocking of the respective channel  4  is not desired. Furthermore, errors can occur. The possibility of decoupling the respective valve member  3  from the respective drive device or, respectively, from the drive wheel  7  then provides an emergency function for the internal combustion engine  2 . 
     According to the  FIGS. 1-5 , the valve unit  1  can additionally be equipped with a sensor  20  by means of which the absolute rotational position of the respective valve member  3  or the two valve members  3  can be determined. 
     In the embodiment shown in  FIG. 5  as well as in the embodiments of the  FIGS. 2 and 4 , two valve members  3  are provided to vary or control the cross-sections, through which a fluid can flow, in two separate channels or channel sections  4 . While in the embodiments of the  FIGS. 2 and 4 , the two valve members  3  are rotationally fixedly connected to a common valve member shaft  10 , the drive train  5  of the embodiment shown in  FIG. 5  has two separate valve member shafts  10  and  10 ′, each of which is rotationally fixedly connected to one of the valve members  3 . Furthermore, the embodiment of  FIG. 5  is equipped with an additional or further phase adjuster  11 ′ by means of which the two valve member shafts  10 ,  10 ′ are drivingly coupled to each other. The further phase adjuster  11 ′ can again be configured as planetary gearing  11 ′ or as any other suitable addition gearing  11 ′. Said further or second planetary gearing  11 ′ has principally the same structure as the previously described first planetary gearing  11 . Here, the sun gear  12  of the second planetary gearing  11 ′ is rotationally fixedly connected to the one valve member shaft  3  while the planetary gear carrier  14  is rotationally fixedly connected to the other valve member shaft  3 . Here too, the annulus gear  15  can 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 members  3  with respect to each other. Through this configuration it is possible to change the quasi synchronously rotating valve members  3  with respect to their relative rotational position. 
     Advantageously, the second planetary gearing  11  is configured in such a manner that, when the annulus gear  15  stands still, it transmits the rotational movement of the one valve member shaft  10  without speed transformation, thus 1:1, to the other valve member shaft  10 ′. Independent of this, the previously described or first planetary gearing  11  can couple the two shafts coupled to the planetary gearing, namely the input shaft  8  and the valve member shaft  10 , to each other without speed transmission, thus without speed change. Alternatively, a gear ratio or a gear reduction is also conceivable for this planetary gearing  11 . 
     According to  FIG. 7 , a reset spring  21  can be allocated to the respective phase adjuster  11  or addition gearing  11  or, respectively, planetary gearing  11 , which spring is illustrated in  FIG. 7  merely in a cursory manner and which drives the two shafts  8 ,  10 ,  10 ′ into a relative initial position. In the example, said reset spring  21  thus serves for driving the annulus gear  15  into an initial position. For this purpose, the reset spring  21  engages with the annulus gear  15 . Alternatively, the reset spring  21  can also engage with the actuator  16 . For transmitting a torque into the annulus gear  15  in order to rotate the annulus gear  15  about the rotational axis  6 , an actuating pin  22  can be attached to the annulus gear  15 , which pin projects from the annulus gear  15  in the shown examples. In the embodiments of the  FIGS. 1-5 , the respective planetary gearing  11  or, respectively,  11 ′ is equipped on its annulus gear  15  in each case with two such actuating pins  22 . The one actuating pin  22  serves, for example, for coupling the respective planetary gearing  11 ,  11 ′ to the actuator  16 , while the other actuating pin  22  then advantageously serves for coupling the respective planetary gear  11 ,  11 ′ to the reset spring  21 . 
     According to  FIG. 6 , the internal combustion engine  2  comprises an engine block  23 , a fresh air path  24  for supplying fresh air to the engine block  23  and an exhaust gas path  25  for discharging exhaust gases from the engine block  23 . Furthermore, a recirculation line  26  is provided here which allows to recirculate exhaust gas from the exhaust gas path  25  to the fresh air path  24 . It is obvious that said recirculation line  26  can also run, at least partially, within the engine block  23 . 
     In the example, the internal combustion engine  2  is also equipped with a charging device  27 . As an example, this can involve an exhaust gas turbocharger, the turbine  28  of which is arranged in the exhaust gas path  25  and is rotationally fixedly connected via a shaft  29  to a compressor  30  which is arranged in the fresh air path  24 . It is particularly useful to connect the recirculation line  26  on the exhaust gas side upstream of the turbine  28  to the exhaust gas path  25  in 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 line  26  downstream of the compressor  30  to the fresh air path  24  to prevent contamination, for example by soot, of the compressor  30 . 
     The internal combustion engine  2  can have at least one valve unit  1  of the above described design. For example, such a valve unit  1  is mounted in the fresh air path  24 . In the region in which the valve unit  1  is integrated, the fresh air path  24  has a channel  4  which is suitable for this. Alternatively, such a valve unit  1  can be mounted in the recirculation line  26  which, at the mounting location of the valve unit  1 , is configured as channel  4 . Furthermore, also conceivable is an embodiment in which one such valve unit  1  can be arranged in each case in the fresh air path  24  as well as in the recirculation line  26 . In any case, the respective valve unit  1  is present in addition to the gas exchange valves of the internal combustion engine  2  or the engine block  23 . The respective valve unit  1  is arranged here in the fresh air path  24  or the recirculation line  26  upstream of the gas exchange valves. 
     The aforementioned drive device  31  for driving the drive wheel  7  can be formed—as illustrated—by a component driven during the operation of the internal combustion engine  2 , for example by the engine block  23 . 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 coupling  31  between the drive train  5  of the respective valve unit  1  with the engine block  23  is indicated in  FIG. 6  by a double arrow with a broken line and designated with  31 . In particular, the respectively selected drive device  31  is configured for permanently driving the drive wheel  7  during the operation of the internal combustion engine  2 . The drive device, which can also be designated with  31 , preferably forms an integral part of the internal combustion engine  2  or the engine block  23 . Furthermore, the respective drive device  31  is suitably configured for driving the drive wheel  7  at a speed which is proportional to the drive speed of the crankshaft of the internal combustion engine  2 . By synchronizing the drive train  5  of the valve unit  1  with the speed of the internal combustion engine  2 , a clear allocation to the gas exchange processes in the individual cylinders of the internal combustion engine  2  takes place. If the crankshaft angle is known, it is also possible to specifically match the switching processes of the valve unit  1  with the gas exchange processes. 
     The valve unit  1  preferably serves for adjusting an exhaust gas rate of the exhaust gas recirculation system. For example, by means of the valve unit  1  arranged in the fresh air path  24 , 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 unit  1 —as in the example shown in FIG.  6 —is arranged, with respect to the charging device  27 , on the pressure side of the fresh air path  24 . 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 line  26 . By controlling or utilizing the pressure oscillations in the fresh air path  24  it is thus possible to control or adjust the exhaust gas recirculation rate. 
     In contrast to that, the valve unit  1  arranged in the recirculation line  26  can 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 path  24 . This also applies in particular if the recirculation line  26 —as in the example shown in FIG.  6 —is connected to the pressure side of the fresh air path  24 . Thus, by controlling the pressure oscillations in the recirculation line  26 , the exhaust gas recirculation rate can be adjusted. 
     The above described two forms of utilization of the valve unit  1  in an internal combustion engine  2  can be implemented alternatively as well as cumulatively. Principally, other mounting situations for the valve unit  1  are also conceivable. For example, such a valve unit  1  can also be arranged in the exhaust gas path  25  downstream of the connection point between recirculation line  26  and exhaust gas path  25  so 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 member  3 , the gas exchange processes and the opening movements or, respectively, closing movements of the valve member  3  work 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 member  3  can be implemented by means of the mentioned actuator  16 . In these settings, the actuator  16  is “statically” actuated, that is, a certain relative rotational position between the shafts  8 ,  10  coupled with the respective phase adjuster or planetary gearing  11 ,  11 ′ is set and maintained at least temporarily. It is principally also possible to actuate the actuator  16  dynamically, whereby it is in particular also possible to vary the opening phases or closing phases of the respective valve member  3 . This can also be utilized for changing the exhaust gas recirculation rate. 
     With respect to the associated valve member  3 , the respective valve member shaft  10  can be a separate component which is rotationally fixedly connected in a suitable manner to the associated valve member  3 . It is also possible to structurally integrate the respective valve member shaft  10  into the associated valve member  3 . In the embodiments shown herein, the valve member  3  is 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 member  3  are also conceivable. Alternatively, the valve member can also be configured as rotary slide valve or the like.