Patent Grant
8201528
EP 1 347 154 A2 discloses a rotary drive designed for an adjustment shaft of a variable valve drive. A first rotatory, hydraulic drive is connected to a second rotatory, hydraulic drive in such a way as to allow rough and fine adjustment of the exact eccentric position within a valve drive chain. In other words, the angle of rotation position to be set is facilitated by a two-stage system.
U.S. Pat. No. 2,911,956 describes a plate-shaped positioner by means of which a pivoting movement of a first plate influences the pivoting range of a second plate and so on.
WO 01/12996 A1 shows in
U.S. Pat. No. 5,233,948 discloses what advantages can be obtained if the cams of superimposed cam shafts are adjustable relative to one another. It is possible to infer from this disclosure the desire to create valve drives which are configured in such a way that they can individually control results of a plurality of gas exchange valves of a combustion chamber. Although this reference discloses the theoretical advantages, there are no proposals for a specific implementation. The basic principles which are theoretically disclosed in this reference are deemed to be incorporated herein by reference.
Approaches for carrying out the teaching of U.S. Pat. No. 5,233,948 are known from FIGS. 4A to 4C of U.S. Pat. No. 5,235,939 which illustrates a coaxial double cam shaft with at least two sets of cams which are angularly offset relative to one another and the cams of which are fastened to the respective carrying cam shaft by fastening pins and fastening springs. A similar arrangement is known from WO 2005/040562 A1. According to the description, the cam position is to be adjusted using hydraulic linear cylinders. A similar design is known from FIG. 1 of DE 43 32 868 A1, which is likewise intended to adjust, by way of a linear movement, the cam position of an inlet cam relative to an outlet cam. The account in EP 0 397 540 A1 also shows a linear-adjustable cam shaft arrangement. FIGS. 5 and 6 of U.S. Pat. No. 4,332,222 disclose a contoured feed pin which influences via its surface the angular distance between two cams and thus the relative position of the connected cam shafts. According to DE 36 24 827 A1, two meshing hollow shaft cam shafts can be adjusted relative to each other in their angular position via a planetary gear with longitudinal holes. However, in order to comply with current exhaust gas values in high-compression combustion engines, the outer shaft must also be adjustable relative to the driving shaft, in particular the crank shaft. DE 199 14 909 A1 discloses further grounds for creating a nested cam contour. The cam contour of the main cam of a cam shaft can be extended by an auxiliary cam in order to activate the associated gas exchange valve a second time, in a time-offset manner relative to the main event, and thus to allow reloading of, or a further outflow from, the cylinder. Finally, reference should also be made to the two documents JP 11 17 31 20 and WO 1992/012 333, which may also be relevant as background information.
In summary, it is clear that it has for years been a recurring consideration how events which are to be offset from one another over time can be made adjustable in their phase positions in the gas exchange valve drive.
DE 10 2005 014 680 A1 shows in certain graphical illustrations a double cam shaft which is equipped with a connected, grooved oil transfer piece, thus allowing the hydraulic oil to be forwarded to a hydraulic adjuster (not shown).
A cam shaft adjuster for the relative rotation of a hollow cam shaft and a second chain wheel arranged parallel to the first chain wheel is described in U.S. Pat. No. 6,253,719. Instead of arranging next to each other the two chain wheel adjusters which are constructed in a disc-type manner, U.S. Pat. No. 6,725,817 B2 show various embodiments of a mutually nested adjuster which lies in the same plane and the first adjustment element of which can rotate a first set of cams of the concentric cam shaft, while the second adjustment element is designed to rotate a second set of cams of the concentric cam shaft. Thus, the angular rotation of one set of cams influences the accessible angular range of the other set of cams. It would be more beneficial if the sets of cams of the double cam shafts could be adjusted, as independently of one another as possible, in a further, larger adjustment range compared thereto.
The statement of object of U.S. Pat. No. 6,076,492 states that it is a problem, even in the case of simply constructed cam shaft adjusters of an axially displaceable type, to orient the cam shaft adjuster, the cylinder head, the control valve and the cam shaft in a stationary, permanent manner. Even in the case of such sufficiently known cam shaft adjusters, there is a risk of the individual components tilting relative to one another.
The described embodiments of two gas exchange valve actuating means which can be offset or adjusted relative to each other on a control shaft are included merely by way of the references thereto in the scope of the description of the present invention in order in this way to increase the readability of the description of the invention and thus to be able to emphasize more clearly the progressive aspects of the present invention.
A gas exchange valve control shaft, which is constructed from two mutually engaging, preferably coaxially arranged cam shafts surrounding the inner cam shaft, is also occasionally referred to herein as a double cam shaft. A double cam shaft is a cam shaft of dual construction. Experts frequently associate with the term “cam shaft” a single shaft on which all cams are arranged stationarily relative to one another.
The aim of the present invention is to provide important parts of a valve drive for internal combustion engines, which valve drive has a cam shaft, such as a gas exchange valve control shaft, with two cams which can be adjusted relative to each other and are located in particular in immediate proximity. This necessitates the design of a suitable cam shaft adjuster which can adjust both the cams relative to a driving shaft and the cams of one type relative to the cams of the other type in as angularly correct a manner as possible under particular operating conditions, the cams being fastened to a corresponding cam shaft. All references in this connection to cams in the plural also include any embodiment in which there is only a single cam of a specific type on a cam shaft. Ideally, the principle of the valve drive may be applied to all previously disclosed applications (offsetting over time of the inlet relative to the outlet gas exchange valves, adjustment in space and/or over time between two similar gas exchange valves of a combustion chamber, the creating of a subsequent opening event, the creating of preceding opening events) of mutually nested cam shafts.
The technical problems noted above are solved by the present invention, which provides a doubled cam shaft adjuster with a layered construction.
A rotor, which is arranged in a specific angular range so as to be able to move back and forth between webs of a stator which can also be configured as part of the surrounding housing, may also be referred to as a rotary vane. The term “rotary vane” refers more to the vane-type appearance of the central, middle, pivotably movable cam shaft linking member, which is frequently referred to as the output body, while the term “rotor” refers more to the rotating property of the output body relative to otherwise conventional axially linear adjustment elements.
The cam shaft adjuster is part of a variable valve drive of an internal combustion engine. The internal combustion engine has at least one gas exchange valve control shaft. The gas exchange valve control shaft has two concentrically arranged cam shafts which are rotationally adjustable relative to each other, so that at least two cams are angularly rotatable relative to one another. A cam shaft adjuster is thus composed of two partial cam shaft adjusters. Each partial cam shaft adjuster can per se, independently of the other partial cam shaft adjuster, sweep the full angular range independently of the position of the other cam shaft adjuster. Each partial cam shaft adjuster relates its relative position to the same external central drive shaft, such as for example the crank shaft. A partial cam shaft adjuster of the cam shaft adjuster operates in accordance with a rotary vane principle and thus allows relative rotation between a drive body and at least one output body. The cam shaft adjuster has two rotary vane adjusters, each of which is associated with a cam shaft, the two rotary vane adjusters being arranged one after the other axially in the shaft direction. The cam shaft adjusters are constructed with their respective cam shafts in a mechanically secure connection.
The cam shaft adjuster, which is designed for controlling a double cam shaft, follows a layered construction. The cam shaft adjuster is equipped with a first rotor-type output body and a second rotor-type output body which are arranged parallel to each other with their rotary vane body parts. Each of the at least two output bodies has a receptacle which is designed for the reception, leading laterally out of the cam shaft adjuster center, of at least one cam shaft of the double cam shaft. A compensating element is provided for axially orienting at least one output body relative to the double cam shaft. The compensating element is an element which avoids jamming and deflection.
According to a further aspect, a difficulty consists in the fact that coaxially arranged components which can tilt relative to one another, such as for example the first rotor, the second rotor, the first cam shaft and the second cam shaft, are exposed to thermal loads and vibrations, so that the components can become jammed relative to one another and relative to the components which are stationary relative thereto, such as a chain wheel. The jamming takes place partly as a result of lateral tilting or an imbalance which causes deflection from the normal line onto a right angle between an individual rotor and a cam shaft. A compensating element, which can for example be a cross joint, can be used to configure the orientation of the outer rotor (e.g., the first rotor) toward the inner cam shaft with orientable play. Advantageously, the compensating element is mounted upstream of a central cam shaft fastening screw which is screwed into the inner cam shaft. The compensating element is located in the axial extension of the doubled cam shaft. The cross-type compensating element as two planes, of which one is intended for engagement with the inner cam shaft and the other plane for engagement with the outer rotor mounted upstream. The non-engaging transverse web region of the cross element has sufficient spacing or play from the surrounding component, i.e. either a rotor or a cam shaft, while the engaging transverse web region rests against its adjacent component in a form-fitting manner. The compensating elements are expediently rotary sliding members or rotary sliding elements. Alternatively, rotary journals may also be employed.
The compensating element is a movable member which creates at least one degree of freedom and allows deflection, in particular differing from a right angle, of the surrounding output body relative to the double cam shaft to be connected, in particular relative to the inner part of the cam shaft. The right angle is sought in relation to the direction of arrangement between the extension of the cam shaft adjuster and the double cam shaft. A right angle, i.e. a 90° angle, is present at the point of transition between the (double) cam shaft adjuster and double cam shaft without deflection of the components relative to one another.
According to one configuration, the compensating element of the cam shaft adjuster is a cross joint. One of the rotary journals of the cross joint can be brought into abutment with the cam shaft. The other journal can be brought, on angling in the opposite direction, into contact with the output member. The cross joint is advantageously selected if particular mechanical stability of the compensating element is required.
According to a further configuration, the compensating element can be a fitting key for a corresponding groove which is in particular embodied in a dually spherical manner. The fitting key allows lateral tilting-out of the output body in a cam shaft axial direction. The cam shaft axial direction is the direction in which the cam shaft extends. The fitting key takes up very little space. A fitting key is a part which is easy to install and to mount.
A particularly large amount of material may be saved if the cam shaft adjuster has just a single axial compensating element. The compensating element provides compensation. The compensation is in the radial, angular and axial direction, i.e. 5 of the 6 degrees of freedom are attained as a result of a configuration of the compensating element. Alternatively, compensating elements of the type having fewer degrees of freedom, for example only 1 degree of freedom, or else 2 or 3 degrees of freedom, are also beneficial. According to an advantageous configuration, the compensating element can be arranged at the side remote from the cam shaft. The cam shaft adjuster can be composed of two parallel individual adjusters. Two rotary vane adjusters are constructed parallel next to each other. Each rotary vane adjuster is uncoupled from the other. They lie uncoupled from each other at an angle of rotation, delimited by two respective webs of a single drive body. The drive body is simply continuous. A single drive body is present. The drive body is regarded as a continuous component. The drive body can also be configured in one piece.
The present invention also provides a variable valve drive of an internal combustion engine. In one example embodiment, the variable valve drive is part of an internal combustion engine with a gas exchange valve control shaft. The gas exchange valve control shaft has a double cam shaft with concentrically arranged cam shafts. The individual cam shafts are rotationally adjustable relative to one another. The adjustment of the cam shafts relative to one another allows at least two cams to be to be angularly rotated relative to one another. The cam shaft adjuster described hereinbefore operates in accordance with the rotary vane principle. The rotary vane principle allows relative rotation between a drive body and at least one output body. An axial compensating element is provided for axially orienting and joining the cam shaft adjuster relative to the gas exchange valve control shaft issuing laterally therefrom. The compensating element has the function of a joint. The compensating element is arranged on the side of the cam shaft adjuster that is remote from the cam shaft. As a result, the compensating element is located at the point of greatest deflection in the event of tilting.
In the variable valve drive, each rotary vane adjuster, a combination of rotor and stator which operates in accordance with the swivel motor principle, is part of a hydraulic swivel motor. The swivel motor operates by carrying out an angular adjustment by way of a hydraulic pressure in two sets of opposing hydraulic chambers. The swivel motor is configured in a rotor-type manner. Each swivel motor is a respective output body of a cam shaft. Each output body comprises a vane crown connected to a rotor core. The vane crown can be moved back and forth between web stops of a surrounding stator housing. The advantages of swivel motor-type cam shaft adjusters are known to those skilled in the art. The advantages of the swivel motor can, according to one aspect of the present invention, be utilized twice.
The gas exchange valve control shaft of the valve drive is a coaxial dual cam shaft. In the case of the gas exchange valve control shaft, a first cam shaft is configured as a hollow body in such a way that a second cam shaft runs in the first cam shaft. The first cam shaft displays at least one recess through which a cam of the second cam shaft protrudes onto the outside of the dual cam shaft. Two cam shafts can now in a space-saving manner be placed running parallel at the location where otherwise only one cam shaft is to be arranged.
The valve drive may have only one drive wheel. The drive wheel may be configured as follows. The cam shaft adjuster has the one drive wheel. The drive wheel can for example be a chain wheel driven by the crank shaft. The valve drive thus has overall only one drive wheel driven by the crank shaft. The drive wheel is according to one configuration arranged on the side that is close to the cam shaft in such a way that a rotatable connection crown runs in synchronisation with the drive wheel for taking over and forwarding the hydraulic fluid to each chamber of the first and the second rotary vane adjuster. Only one connection crown is therefore provided, in order to minimise the number of components.
Two feed line channels, which are arranged closer to the cam shaft axis, lead from the connection crown into the rotary vane adjuster which is arranged further apart from the introduction points of the connection crown. Two feed line channels, which are arranged further apart from the cam shaft axis, lead into the rotary vane adjuster which is close to the connection crown. The channels can therefore be arranged parallel to the cam shaft adjuster axis over a significant stretch. The oil flows freely into the respective chamber to be activated.
According to a further exemplary embodiment, the oil conveying channels can also be fed from an face of the cam shaft adjuster to the respective chambers of the different types (advance chamber and retard chamber) using an oil distributor. At least four channels are provided for this purpose. In one example embodiment, each channel has a length differing from the other channels. The channels open into the end-side chamber feed lines which can be configured in a planar manner. The conveyance of oil is likewise easy to establish and very reliable.
The output body which may be remote from the gas exchange valve control shaft is designed for adjusting an inner cam shaft. The output body, which may be arranged closer toward the gas exchange valve control shaft, is designed for adjusting an outer cam shaft surrounding the inner cam shaft. The determination takes place by way of secure, permanent fixing, such as for example screwing, shrinking-on or welding. According to one configuration, the remote output body can therefore be screwed at the face onto the inner cam shaft. The output body facing the cam shaft can be shrunk onto the outer cam shaft.
The connection crown has at least four hydraulic ports. The connection crown is the point for transfer of the hydraulic medium between a stationary arrangement and a moving part, namely the valve drive control shaft. In order to forward from a stationary bearing ring, which is configured in particular as part of the cylinder head of an internal combustion engine, individually adjustable hydraulic fluids in hydraulic chambers of each rotary vane adjuster, the ports, at least four ports, are formed in the connection crown.
In order to set the gas exchange valve control shaft to a preferred position or situation, or to ensure that a constrained position is assumed under particular operating states such as start, stop or failure, a spring is inserted into the drive wheel. The drive wheel can be pressed by the spring into a specific position. The spring is in a flat configuration and may be, for example, a spiral spring. The spring is supported at one side on the drive wheel in order to press at least one of the two rotary vane adjusters into a constrained position.
Because all that matters for true running of the internal combustion engine is that the absolute settings of the angular relationship of the individual cam shafts to the driving shaft remains, in accordance with an adjustment process, within a maximum selected oscillation bandwidth, compensating elements as simple as a cross joint or a longitudinally movable fitting key can be used for directional orientation between the output member and cam shaft. Jamming is reliably suppressed as a result of the angular movability of the outer part of the cam shaft adjuster, the outer output member.
The present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like reference numerals denote like elements, and:
The ensuing detailed description provides exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the ensuing detailed description of the exemplary embodiments will provide those skilled in the art with an enabling description for implementing an embodiment of the invention. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the invention as set forth in the appended claims.
A possible configuration of the interlocking mechanism, consisting inter alia of the following parts: locking pin 34, locking pin spring 35 and spring bearing 36, can be observed in a design configuration in
The hydraulic medium, oil, is applied to the face of the cam shaft adjuster 1 according to
A further configuration according to the invention of a cam shaft adjuster 1 with two cam shafts 16, 18 may be seen in
The compensating element 56 according to
As a result of compensating elements 50 such as fitting key 56 or a cross joint 51, the angle of rotation φ for each rotor 4, 5 and the cam shaft 16, 18 connected thereto is preserved irrespective of the rotational behavior of the other rotor 5, 4 despite the gas exchange valves control shaft 102 which is extended in an elongate manner on the cam shaft axis 38.
The inner cam shaft 18 may be configured in a solid manner. A cast cam shaft can for example be used. The outer cam shaft 16, surrounding the inner cam shaft 18, can be configured as a hollow body cam shaft. The hollow body cam shaft, which is also referred to as a hollow cam shaft, can be a constructed cam shaft.
An adapter 11 can be provided between the respective cam shaft 16, 18 and the respective rotor 5, 4. As a result of the interposition of an adapter 11, the rotor 5 can be constructed in an identical manner to rotor 4. This allows the number of identical parts to be increased. Although in the relatively schematic contrast of
Any person skilled in the art will understand that, in addition to the illustrated exemplary embodiments, the teaching according to the invention can also be carried out in a combination of the various exemplary embodiments. Thus, it is possible to provide, in the case of an oil supply conveyed via cam shaft bearings, a distributing journal with stepped, fanned-out ends for supplying oil to the chambers of the two cam shaft adjusters. Equally, it is possible also to arrange more than two, i.e. three or four, rotors, which do not restrict one another in the angular pivoting range, parallel to one another on the same axis.
It should now be appreciated that the present invention provides advantageous methods and apparatus a cam shaft adjuster for controlling a double cam shaft.
Although the invention has been described in connection with various illustrated embodiments, numerous modifications and adaptations may be made thereto without departing from the spirit and scope of the invention as set forth in the claims.
This application claims the benefit of U.S. Provisional Patent Application No. 61/010,179, filed Jan. 4, 2008, which is incorporated herein and made a part hereof by reference. The present invention relates to a valve drive of an internal combustion engine with a doubled cam shaft.
| Number | Name | Date | Kind |
|---|---|---|---|
| 2911956 | Smith, Jr. | Nov 1959 | A |
| 4332222 | Papez | Jun 1982 | A |
| 5233948 | Boggs et al. | Aug 1993 | A |
| 5235939 | Levin et al. | Aug 1993 | A |
| 6076492 | Takahashi | Jun 2000 | A |
| 6253719 | Methley | Jul 2001 | B1 |
| 6510827 | Schreeck et al. | Jan 2003 | B2 |
| 6546842 | Raikamo | Apr 2003 | B2 |
| 6725817 | Methley et al. | Apr 2004 | B2 |
| 6814036 | Palesch et al. | Nov 2004 | B2 |
| 6832583 | Hayman | Dec 2004 | B2 |
| 6945205 | Heintzen et al. | Sep 2005 | B2 |
| 7004130 | Bolz et al. | Feb 2006 | B2 |
| 7270096 | Lancefield et al. | Sep 2007 | B2 |
| 7284517 | Lancefield et al. | Oct 2007 | B2 |
| 7287499 | Lawrence et al. | Oct 2007 | B2 |
| 7503293 | Lettmann et al. | Mar 2009 | B2 |
| 7610890 | Lettmann et al. | Nov 2009 | B2 |
| 7841311 | Hutcheson et al. | Nov 2010 | B2 |
| 20020059910 | Methley et al. | May 2002 | A1 |
| 20020096044 | Raikamo | Jul 2002 | A1 |
| 20020104497 | Schreeck et al. | Aug 2002 | A1 |
| 20030177991 | Palesch et al. | Sep 2003 | A1 |
| 20040226524 | Hayman | Nov 2004 | A1 |
| 20050109298 | Bolz et al. | May 2005 | A1 |
| 20060185471 | Lawrence et al. | Aug 2006 | A1 |
| 20070034182 | Dengler | Feb 2007 | A1 |
| 20070039411 | Lechner et al. | Feb 2007 | A1 |
| 20070240657 | Schneider | Oct 2007 | A1 |
| 20080257290 | Lettmann et al. | Oct 2008 | A1 |
| 20090223470 | Rozario et al. | Sep 2009 | A1 |
| Number | Date | Country |
|---|---|---|
| 36 24 827 | Feb 1988 | DE |
| 43 32 868 | Mar 1995 | DE |
| 199 14 909 | Oct 2000 | DE |
| 101 02 767 | Jul 2002 | DE |
| 10 2004 023 451 | Dec 2004 | DE |
| 102004024222 | Mar 2005 | DE |
| 103 46 446 | May 2005 | DE |
| 103 46 448 | Jun 2005 | DE |
| 10 2005 014 680 | Aug 2006 | DE |
| 0 397 540 | Nov 1990 | EP |
| 1 234 954 | Aug 2002 | EP |
| 1 347 154 | Sep 2003 | EP |
| 1 696 107 | Aug 2006 | EP |
| 11-173120 | Jun 1999 | JP |
| 9212333 | Jul 1992 | WO |
| 0112996 | Feb 2001 | WO |
| 2005040562 | May 2005 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20090183702 A1 | Jul 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61010179 | Jan 2008 | US |
