Patent Application
20240035398
The invention relates to a sliding cam system for an internal combustion engine according to the preamble of claim 1.
A sliding cam system of the abovementioned type is known for example from DE 10 2011 054 218 A1.
In the known sliding cam system, a rotatably mounted camshaft is provided. The camshaft comprises a plurality of sliding cams. The sliding cams are axially movable. The axial movement of the sliding cams is initiated by an actuator.
To this end, a coupling rod is fixedly connected via a shifting fork to a sliding cam which is axially moved directly by the actuator. During an axial movement of the sliding cam, the coupling rod moves with the sliding cam.
The coupling rod comprises gates. The gates are fixedly connected to the coupling rod. The gates are each associated with a further sliding cam. The further sliding cams have pins which cooperate with the respectively associated cams such that the further sliding cams are moved in accordance with the movement of the sliding cam fixedly connected to the coupling rod.
The applicant's patent application PCT/EP2020/058182, or DE 10 2019 107 626.9, discloses a sliding cam system for an internal combustion engine having at least one camshaft, comprising a carrier shaft with at least two sliding cam elements. The sliding cam elements each comprise a shifting gate with at least one shifting groove, wherein the sliding cam elements are displaceable axially with respect to the carrier shaft by at least one actuator pin. Arranged parallel to a longitudinal axis of the carrier shaft is at least one adjusting element, wherein the adjusting element is axially displaceable in the direction of the longitudinal axis of the carrier shaft.
Although an advantageous sliding cam system is already proposed therein, it is still possible to make improvements, in particular with regard to the maximum shifting speed and the masses to be moved.
Thus, in the prior art, in particular in the sliding cam system according to PCT/EP2020/058182, or DE 10 2019 107 626.9, the displacement region of the shifting grooves is limited to in each case 120°NW, this ultimately representing the groove length of the respective sliding cam element that is used for displacement. The masses to be moved of the sliding camshaft and ultimately the maximum shifting speed are in turn limited by the resultant kinematics.
This is where the present invention takes effect, setting itself the object of providing an improved sliding cam system, in particular of specifying a sliding cam system in which axial displacement of a sliding cam element at an increased speed and/or axial displacement of a sliding cam element with a greater mass can be achieved.
According to the invention, this object is achieved by a sliding cam system having the characterizing features of claim 1.
Since the sliding cam system is designed such that a shifting operation of first secondary sliding cam element takes place at least partially at the same time as the shifting operation of the secondary sliding cam element, the sliding region can be enlarged and thus axial displacement of a sliding cam element at an increased speed and/or axial displacement of a sliding cam element with a greater mass can be achieved compared with a known sliding cam system.
Further advantageous configurations of the proposed invention can be found in particular in the features of the dependent claims. The subjects or features of the different claims can in principle be combined with one another as desired.
In one advantageous configuration of the invention, it may be provided that the sliding cam system is designed such that the shifting operation of a first secondary sliding cam element begins immediately after the end of the shifting operation of the primary sliding cam element, and that the shifting operation of a second secondary sliding cam element begins after the beginning and before the end of the shifting operation of the first secondary sliding cam element.
In a further advantageous configuration of the invention, it may be provided that the sliding cam system is designed such that the beginning of the shifting operation of a first secondary sliding cam element and the beginning of the shifting operation of a second secondary sliding cam element take place at the same time.
In a further advantageous configuration of the invention, it may be provided that the lengths of the displacement regions of the sliding cam elements are the same, in particular that °NW 121a/S=°NW 121b/S=°NW 121c/S.
In a further advantageous configuration of the invention, it may be provided that the lengths of the displacement regions of all the sliding cam elements are different, in particular that °NW 121a/S #°NW 121b/S #°NW 121c/S.
In a further advantageous configuration of the invention, it may be provided that the displacement regions of the sliding cam elements are greater than 120°NW, in particular that °NW 121a/S>120° and °NW 121b/S>120° and °NW 121c/S>120°, respectively.
In a further advantageous configuration of the invention, it may be provided that the beginning of the shifting portion °NW121b/SA with respect to the cam start °NW122b/NA is not the same as the beginning of the shifting portion °NW121c/SA with respect to the cam start °NW122c/NA, in other words that the angular position of the displacement region with respect to the respective cam tip is different for the secondary sliding cam elements, in particular that °NW121b/SA with respect to °NW122b/NA is not the same as °NW121c/SA with respect to °NW122c/NA.
In a further advantageous configuration of the invention, it may be provided that the length of the displacement region of the first shifting groove on the primary sliding cam element is greater than the length of the displacement regions of the shifting grooves on the secondary sliding cam elements.
In a further advantageous configuration of the invention, it may be provided that the length of the displacement region of the shifting groove on at least one secondary sliding cam element is greater than the length of the displacement region on the primary sliding cam element and/or possibly further secondary sliding cam elements.
In a further advantageous configuration of the invention, it may be provided that more than two secondary sliding cam elements are coupled to a connecting element.
In a further advantageous configuration of the invention, it may be provided that the secondary sliding cam elements are not identical parts, in particular in terms of the displacement region and/or cam contour.
In a further advantageous configuration of the invention, it may be provided that the cam contours of the secondary sliding cam elements are arranged identically, in particular are arranged so as to be offset at an angle, for example offset at 120°, only in accordance with the ignition sequence, and are embodied identically with regard to the cam contour. However, depending on the thermodynamic demand, both the arrangement and the cam profile shape/cam profile length may differ.
In a further advantageous configuration of the invention, it may be provided that the sliding cam system is designed such that the shifting operation of the primary sliding cam element ends before the shifting operation of a second secondary sliding cam element takes place. Preferably, the displacement of the primary sliding cam element takes place only while the blocking disk is unblocked and the displacement of the secondary cam elements can preferably take place only when the blocking disk is blocked.
In a further advantageous configuration of the invention, it may be provided that the sliding cam system is designed such that the shifting operation of a first secondary sliding cam element begins immediately after the end of the shifting operation of the primary sliding cam element, wherein in particular the shifting operation of a further (second) secondary sliding cam element begins preferably after the beginning and before the end of the shifting operation of the first secondary sliding cam element.
Further features and advantages of the invention will become apparent from the following description of preferred exemplary embodiments with reference to the accompanying drawings, in which:
The sliding cam system for an internal combustion engine having at least one camshaft 10 comprises a carrier shaft 11. A primary sliding cam element 12a and a first secondary sliding cam element 12b are arranged on the carrier shaft so as to be axially movable with respect to a longitudinal axis of the carrier shaft 11 and in particular for conjoint rotation. It is conceivable for more than two sliding cam elements to be arranged on the carrier shaft 11. The carrier shaft 11 comprises preferably three rolling bearings 20. One rolling bearing 20 is arranged on each of the axial ends of the carrier shaft 11 and a further rolling bearing 20 is arranged between the sliding cam elements 12a, 12b. The rolling bearings 20 are preferably locked by retaining rings 21. The number of rolling bearings 20 and of retaining rings 21 and the positions of the bearing points are variable. The sliding cam elements 12a, 12b comprise a shifting gate 13 and a cam contour 22.
The shifting gate 13 of the first sliding cam element 12a comprises a first and a second shifting groove 14a, 14b. The shifting grooves 14a, 14b are V-shaped at least in portions. In other words, the width of the two shifting grooves 14a, 14b is not constant. The width should be understood as being the distance between the flanks of the shifting grooves 14a, 14b in an axial direction with respect to the carrier shaft 11. The flanks of the shifting grooves 14a, 14b approach one another in the V-shaped portion.
The two shifting grooves 14a, 14b are preferably arranged at the same rotational angle. The first shifting groove 14a preferably has a larger radius than the second shifting groove 14b.
The radius should be understood as being the size of the distance of the groove bottom surface of the first or the second shifting groove 14a, 14b from the longitudinal center axis of the carrier shaft 11. Thus, the outside diameter of the shifting gate 13 and the radius of the groove bottom surface determine the groove depth.
The first shifting groove 14a preferably comprises a step. In other words, the first shifting groove 14a is in the form of a protrusion or shoulder. The first shifting groove 14a preferably has a varying radius. In other words, the first shifting groove 14a has, in portions, regions with a larger radius and regions with a smaller radius. The radius changes steplessly. The regions are each assigned to an entry region, an exit region and a displacement region.
The second shifting groove 14b preferably has a constant radius. The width of the second shifting groove 14b is smaller than the width of the first shifting groove 14a.
Two actuator pins 15 are arranged on the carrier shaft 11. The actuator pins 15 are movable substantially only in a direction orthogonal to the longitudinal center axis of the carrier shaft 11. The actuator pins 15 are assigned to the first shifting groove 14a. In other words, the actuator pins cooperate only with the first shifting groove 14a. The actuator pins 15 are spaced apart from one another in the axial direction of the carrier shaft 11. As a result, depending on the position of the primary sliding cam element, one of the two actuator pins 15 is introducible into the first shifting groove 14a. As a result of the introduction of the actuator pin 15, an axial movement of the primary sliding cam element 14a is able to be initiated.
To this end, an actuator pin 15 is introduced into the first shifting groove 14a. As a result of the reduction in the groove width, the introduced actuator pin 15 cooperates with a flank of the first shifting groove 14a. More specifically, the introduced actuator pin 15 exerts, on a flank of the first shifting groove 14a, a force directed counter to the flank. As a result, the axial displacement of the primary sliding cam element 12a takes place. The direction of the displacement thus depends on the flank with which the introduced actuator pin 15 cooperates. Each flank of the first shifting groove 14a is assigned an actuator pin 15.
Arranged parallel to the carrier shaft 11 is an adjusting element 16. The adjusting element 16 is axially movable. The adjusting element is offset through 90° with respect to the actuator pins 15. Alternatively, other angular offsets are conceivable. The adjusting element 16 comprises a first and a second coupling pin 17a, 17b and a receiving element 18. The first and the second coupling pin 17a, 17b are each arranged at an axial end of the adjusting element 16. The receiving element 18 comprises three extensions and is arranged between the axial ends of the adjusting element 16. The coupling pins 17a, 17b and the receiving element 18 extend orthogonally to the longitudinal center axis of the carrier shaft 11.
The first coupling pin 17a is assigned to the second shifting groove 14b of the primary sliding cam element 12a. The first and the second coupling pin 17a, 17b are arranged on the adjusting element 16 so as to be substantially rotatable. The first coupling pin 17a is permanently in engagement with the second shifting groove 14b of the primary sliding cam element 12a.
The first coupling pin 17a is subjected to a force by a flank of the second shifting groove 14b. The adjusting element 16 is displaced in the direction of action of the force. Since the adjusting element 16 and thus the coupling pins 17a, 17b are offset through 90° in the circumferential direction with respect to one another and the first and the second shifting groove 14a, 14b are arranged at an identical rotational angle, the displacement of the adjusting element 16 accordingly takes place in a time-offset or phase-shifted manner.
The second coupling pin 17b is arranged in the region of the first secondary sliding cam element 12b. The first secondary sliding cam element 12b comprises a shifting groove 14. The shifting groove 14 has a V-shaped portion. The second coupling pin 17b is permanently engaged with the shifting groove 14. The shifting groove 14 of the first secondary sliding cam element 12b is arranged such that it is possible to shift the first secondary sliding cam element 12b with a time offset with respect to the primary sliding cam element 12a.
As a result of the displacement of the adjusting element 16, the second coupling pin 17b is moved axially in the shifting groove 14. More specifically, the second coupling pin 17b is moved toward one of the flanks of the shifting groove 14. The second coupling pin 17b cooperates with the shifting groove 14 substantially in the same way as the actuator pins 15 cooperate with the first shifting groove 14a of the primary sliding cam element 12a.
The carrier shaft 11 comprises a locking element 19 in the form of a circular disk. Alternatively, other geometries are conceivable. The locking element 19 is arranged between the first and the first secondary sliding cam element 12a, 12b. The locking element 19 is axially delimited by the receiving element 18. The locking element 19 has a supporting function. The locking element 19 forms a counter bearing for the receiving element 18. The locking element 19 absorbs the forces during the shifting operation and thus allows the adjusting element 16 to be fixed. Furthermore, the cooperation of the receiving element 18 and the locking element 19 prevents the primary sliding cam element 12a from being unintentionally displaced. The receiving element 18 comprises two receptacles for the locking element 19. The locking element 19 comprises a cutout. As a result, it is possible for the adjusting element to be displaced through the circular disk. To this end, the cutout is arranged in the region of the corresponding rotational angle. The cutout is arranged in the circular disk such that, during an axial movement, the adjusting element 16 is moved through the cutout. It is conceivable for the adjusting element 16 to additionally comprise a spring/ball locking means (not illustrated).
In summary, the above-described sliding cam system, as a result of the adjusting element 16, allows phase-shifted shifting of the sliding cam elements 12a, 12b using a single actuator. As a result, the total number of actuators in the sliding cam system is able to be considerably reduced.
Preferably, the locking element 19 is arranged between the second and the third sliding cam element 12b, 12c. The locking element 19 comprises a circular disk with a cutout. In the region of the circular disk, an extension is arranged on the adjusting element 16. The circular disk forms a counter bearing for the extension. The circular disk cooperates with the extension during a displacement movement such that the first coupling pin is relieved of load during the displacement movement. In other words, the extension is supported against the circular disk. The cutout is arranged at the rotational angle at which the displacement of the first adjusting element 16 takes place. An actuator is identified by the reference sign 23.
In the diagram according to
In the diagram according to
The blocking regions of the blocking disk or locking element 19 are also plotted in the diagram according to
For further details and further embodiments, reference may be made to the applicant's PCT/EP2020/058182, or DE 10 2019 107 626.9, to which reference is expressly made here.
Further improvements with regard to the shifting of the sliding cam elements are described in the following text.
A preferred embodiment of the present invention is illustrated in
The sliding cam elements each have a shifting groove 121a, 121a″, 121b, 121c, meaning that the primary sliding cam element 12a has the shifting grooves 121a and 121a″, the first secondary sliding cam element 12b has the shifting groove 121b and the second secondary sliding cam element 12c has the shifting groove 121c.
The shifting groove 121a is intended for the engagement of the actuator pins 15, whereas the shifting groove 121a″ is intended for the engagement of the first shifting pin 17a of the connecting element 16.
The shifting groove 121b is accordingly provided for the engagement of the second shifting pin 17b and the shifting groove 121c is accordingly provided for the engagement of the third shifting pin 17c.
The operating principle as set out above; the primary sliding cam element 12a is axially displaced in a targeted manner into the shifting groove 121a via the actuator or the engagement of the actuator pin 15 during the rotation of the camshaft 10. The adjusting element 16 is axially displaced via the engagement of the first shifting pin 17a in the shifting groove 121a″, with the result that the shifting pins 17b and 17c are likewise displaced in a corresponding manner.
The shifting groove 121a of the primary sliding cam element 12a has, in the circumferential direction, at least one displacement region 121a/S and a freewheel region 121a/F. The displacement region 121a/S is characterized in particular by a shifting groove side wall that is inclined with respect to the longitudinal axis/axis of rotation L of the primary sliding cam element 12a or carrier shaft. In other words, this is the region with which the primary element 12a and, as a result of the operative connection between the shifting groove 121a″ and the shifting pin 17a, the connecting element 16 is axially displaced. The freewheel region is, by comparison, that region of the shifting groove 121a in which no axial displacement of the connecting element 16 takes place. The displacement region can also be referred to as a shifting region.
The shifting groove 121b of the first secondary sliding cam element 12b has, in the circumferential direction, at least one displacement region 121b/S and a freewheel region 121b/F. The displacement region 121b/S is characterized in particular by a shifting groove side wall that is inclined with respect to the longitudinal axis/axis of rotation L of the secondary sliding cam element 12b or carrier shaft. In other words, this is the region against which a displaced shifting pin 17b bears and displaces the secondary sliding cam element 12b axially in the desired direction. The freewheel region is, by comparison, that region of the shifting groove 121b in which no axial displacement of the secondary sliding cam element 12b takes place. This region is characterized in particular in that, during the movement of the connecting element, there is no contact with the shifting groove side wall.
To avoid repetitions, it may also be noted that the second secondary sliding cam element 12c and the shifting groove 121c thereof have a displacement region 121c/S and a freewheel region 121c/F. The shifting pin 17c of the adjusting element 16 engages in a corresponding manner here. With regard to the function, reference may be made to the preceding paragraph about the first secondary sliding cam element 12b.
The sliding cam elements each have at least two cam contours. One cam contour may also be in the form of a so-called zero lift cam. The cam contours differ from one another and result in particular in different lifts of the controlled valve (not illustrated).
The primary sliding cam element 12a has preferably a first cam contour 122a and a second cam contour 122a″. The first secondary sliding cam element 12b has preferably a first cam contour 122b and a second cam contour 122b″. The second secondary sliding cam element 12c has preferably a first cam contour 122c and a second cam contour 122c″. No cam contour of the primary sliding cam element 12a has been illustrated in
The displacement regions can be defined more closely in terms of their angular length, and in terms of their start and their end.
Thus, the angular lengths:
The invention provides that the sliding cam system is designed such that a shifting operation of the first secondary sliding cam element 12b takes place at least partially at the same time as the shifting operation of the second secondary sliding cam element 12c.
The partially simultaneous shifting of the secondary sliding cam elements is understood according to the invention as follows: that the displacement regions of the respective secondary displacement gates are angularly oriented with respect to one another such that they have portions in which the coupling pin of the adjusting element for axially displacing the first secondary sliding cam element and the coupling pin of the adjusting element for axially displacing the second secondary sliding cam element are in operative contact at the same time (concurrently) such that an axial displacement of the second secondary cam element begins at least while the axial displacement of the first secondary sliding cam element is taking place.
The angular orientation, i.e. the arrangement and length of the respective corresponding displacement regions of the secondary gates are in this case always dependent on the type of motor or the respective installation space requirements of the internal combustion engine, for example the radial arrangement and position of the adjusting element.
The angular orientation, i.e. the arrangement and length of the respective corresponding displacement regions of the secondary gates are in this case always dependent on the type of motor or the respective installation space requirements of the internal combustion engine, for example the radial arrangement and position of the adjusting element.
Preferably, it may be provided that the sliding cam system is designed such that the shifting operation of the first secondary sliding cam element 12b begins immediately after the end of the shifting operation of the primary sliding cam element 12a, and that the shifting operation of the second secondary sliding cam element 12c begins after the beginning and before the end of the shifting operation of the first secondary sliding cam element 12b.
Further preferably, it may be provided that the sliding cam system is designed such that the beginning of the shifting operation of the first secondary sliding cam element 12b and the beginning of the shifting operation of the second secondary sliding cam element 12c take place at the same time.
Further preferably, it may be provided that the radial lengths of the displacement regions °NW121a/S, °NW121b/S and °NW121c/S (angular regions) of all the sliding cam elements 12a, 12b, 12c are the same, in particular that °NW121a/S=°NW121b/S=°NW121c/S.
Further preferably, it may be provided that the radial lengths of the displacement regions °NW121a/S, °NW121b/S and °NW121c/S (angular regions) of all the sliding cam elements 12a, 12b, 12c are different, in particular in that °NW121a/S #°NW121b/S #°NW121c/S.
Further preferably, it may be provided that the displacement regions of the sliding cam elements are greater than 120°NW, in particular that °NW121a/S>120° and °NW121b/S>120° and °NW121c/S>120°, respectively.
Further preferably, it may be provided that the sliding cam system is designed such that the offset of the shifting portion °NW121b/SA with respect to the cam start °NW122b/NA is not the same as the offset of the shifting portion °NW121c/SA with respect to the cam start °NW122c/NA.
Further preferably, it may be provided that the length of the displacement region °NW121a/S of the first shifting groove 121a on the primary sliding cam element 12a is greater than the length of the displacement regions °NW121b/S and °NW121c/S, respectively, of the shifting grooves 121b and 121c, respectively on the secondary sliding cam elements 12b and 12c, respectively.
Further preferably, it may be provided that the length of the displacement region °NW121b/S or °NW121c/S, respectively, of the shifting groove 121b or 121c, respectively, on at least one secondary sliding cam element 12b or 12c, respectively, is greater than the length of the displacement region °NW121a/S on the primary sliding cam element 12a and/or possibly further secondary sliding cam elements (°NW121x/S and 12x, respectively). The x stands here as an index for further secondary sliding cam elements.
Further preferably, it may be provided that more than two secondary sliding cam elements 12b, 12c are coupled to a connecting element 16, in particular in applications in internal combustion engines having more than 3 cylinders in a series arrangement. It may preferably be provided that the shifting groove on a secondary sliding element is larger than on the primary sliding element and/or larger than on at least one further secondary sliding element.
The sliding cam system is also usable for 5, 6, 8, 10, 12 cylinder internal combustion engines. The sliding cam system may also be configured with three (or more) stages with regard to the number of cam contours 122xy. “X” stands here as an index for the respective sliding cam element, and “Y” stands here as an index for the respective cam contour.
Compared with a sliding cam system according to the prior art, as a result of the present invention, the length and the arrangement of the displacement grooves (region of the axial displacement) of the secondary shifting gates with regard to the respective cam tip is modified such that ultimately overlapping shifting of the secondary elements is achieved.
This can result, in the primary sliding cam element 12a and in the secondary sliding cam elements 12b and 12c, in an angular length of the displacement region 121a/S of the primary sliding cam element 12a of °NW121a/S>120°, an angular length of the displacement region 121b/S of the first secondary sliding cam element 12b of °NW121b/S>120° and/or an angular length of the displacement region 121c/S of the second secondary sliding cam element 12c of °NW121c/S>120°, in particular in an angular length °NW121a/S, °NW121b/S, °NW121c/S of the displacement regions 121a/S, 121b/S, 121c/S of the shifting grooves 121a, 121b, 121c of, for example, 153°NW each.
It may furthermore preferably be provided that the angular position of the displacement region with respect to the respective cam tip is different for the secondary sliding cam elements, in particular that °NW121b/SA with respect to °NW122b/NA is not the same as °NW121c/SA with respect to °NW122c/NA.
It may furthermore preferably be provided that secondary sliding cam elements are not identical parts, in particular in terms of the displacement region (arrangement, length) and/or cam contour (arrangement, length).
The arrangement of the displacement regions with respect to the respective cam tip should be different, and the length may be different. If the secondary cams have different mass properties, the shifting behavior may for example be adapted such that the length of the shifting grooves is coordinated with the mass.
In a particular and preferred configuration of the invention, it may be provided that the beginning of the shifting portion °NW121b/SA with respect to the cam tip NS122b of the first secondary sliding cam amounts to 143° and the beginning of the shifting portion NW121c/SA with respect to the cam tip NS122c of the second secondary sliding cam amounts to 203°, in other words that the angular position of the displacement region with respect to the respective cam tip is different for the secondary sliding cam elements, in particular that °NW121b/SA with respect to NS122b is not the same as °NW121c/SA with respect to NS122c.
It may furthermore preferably be provided that the cam contours of the secondary sliding cam elements are arranged identically, in particular are arranged so as to be offset at an angle, for example offset at 120°, only in accordance with the ignition sequence, and are embodied identically with regard to the cam contour. However, depending on the thermodynamic demand, both the arrangement and the cam profile shape/cam profile length may differ.
In particular with regard to the ““lift [mm]/blocking region [ ] over the angle [°NW]” diagram for a sliding cam system according to the invention according to
Furthermore, with regard to the diagram according to
In the diagram according to
In the diagram according to
The blocking regions of the blocking disk or locking element 19 are also plotted in the diagram according to
A “region of simultaneity of the axial movement of the secondary sliding cam elements” has also been plotted as BG. Here, the overlapping, essential to the invention, of the axial displacement of the secondary sliding cam elements is apparent.
It is also apparent, but not inherently essential to the invention, that the valve lifts that result from the first cam contours 122a, 122b, 122c as “FL profile cyl. 1”, “FL profile cyl. 2” and “FL profile cyl. 3” and the valve strokes that result from the first cam contours 122a″, 122b″ and 122c″ as “PL profile cyl. 1”, “PL profile cyl. 2” and “PL profile cyl. 3” temporally overlap.
Features and details that are described in conjunction with a method self-evidently also apply in conjunction with the device according to the invention and vice versa, such that reference is always or can always be made reciprocally with respect to the disclosure of the individual aspects of the invention. Furthermore, an optionally described method according to the invention can be carried out with the device according to the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 210 259.7 | Aug 2020 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/072306 | 8/10/2021 | WO |
