SLIDING CAMSHAFT ASSEMBLY
A camshaft assembly includes an actuator and an axially moveable structure mounted to a base shaft wherein the axially moveable structure includes a plurality of lobe packs and a cam barrel. The axially movable structure moves along the base shaft in the axial direction along a longitudinal axis of the base shaft, but is rotationally fixed to the base shaft. The barrel cam includes an inner wall and an outer wall which defines a control groove therebetween. The control groove further defines first and second regions wherein the first region includes a fixed narrow control groove width and the second region includes a progressively decreasing control groove width. The actuator shifts the axially moveable structure relative to the base shaft between a first position and a second position. A recess is defined in the outer wall such that the recess is disposed adjacent to the first region.
The present disclosure relates to a sliding camshaft for a vehicle engine.
BACKGROUNDIn modern internal combustion engines, variable valve drives, with which different valve strokes can be set at the gas exchange valves of the internal combustion engine, are used to optimize the charge movement in the combustion chamber. The axial displacement of the cam causes a different valve stroke to be set at the respective gas exchange valve. The traditional valve drive includes a sliding cam which is mounted in a rotationally fixed but axially displaceable fashion on a camshaft wherein the sliding cam may further include a cam barrel with a plurality of grooves, and in which in order to bring about axial displacement of the sliding cam an actuator having a plurality of pins which can be activated is provided. The cam barrel may have a first, right-handed groove and a second, left-handed groove which are arranged one next to the other on the circumference of the cam barrel and merge with a common run-out groove. The pins of the actuator interact with the grooves of the cam barrel.
In addition, a valve drive is already known in which the grooves of the cam barrel are positioned one behind the other on the circumference of the cam barrel, specifically a first groove for axial displacement of the sliding cam in a first direction and a second groove for axial displacement of the sliding cam in an opposing second direction. In this valve drive, the actuator also has a plurality of pins which can be activated in order to bring about axial displacement of the sliding cam, specifically a first pin for axial displacement of the sliding cam in the two directions about a first axial segment and a second pin for axial displacement of the sliding cam in the two directions about a second axial segment.
For the engine control of an internal combustion engine having such a valve drive which has at least one displaceable sliding cam, it is necessary to have knowledge of the relative position of the sliding cam on the camshaft and therefore of the cam lobes relative to the gas exchange valve of the internal combustion engine which is to be activated. Hitherto, it was difficult to detect in a certain and reliable way the relative position of the sliding cam on the camshaft and therefore the relative position of the cam tracks with respect to the gas exchange valve which is to be activated.
SUMMARYIn one embodiment of the present disclosure, a camshaft assembly is provided wherein the camshaft assembly includes an actuator and an axially moveable structure mounted to a base shaft wherein the axially moveable structure includes a plurality of lobe packs and a cam barrel. The axially movable structure moves along the base shaft in the axial direction along a longitudinal axis of the base shaft, but is rotationally fixed to the base shaft. The barrel cam includes an inner wall and an outer wall which defines a control groove therebetween. The control groove further includes first and second regions wherein the second region defines a fixed narrow control groove width and the first region includes a progressively changing control groove width. The actuator shifts the axially moveable structure relative to the base shaft between a first position and a second position. A recess is defined in the outer wall of the barrel such that the recess is disposed adjacent to the second region of the control groove.
The camshaft assembly may further include a sensor configured to align with the axially moveable structure along a first sensor path when the axially moveable structure moves to the first position. The aforementioned sensor may also be configured to align with the axially moveable structure along a second sensor path when the axially moveable structure moves to the second position. The first sensor path overlays the outer wall and the recess defined in the outer wall. The second sensor path overlays the control groove and the outer wall. However, it is understood that the recess is disposed outside of the second sensor path. Thus, the aforementioned camshaft assembly of the present disclosure may also include an engine control module in communication with the actuator and the sensor.
The recess and outer wall may be configured to communicate to an engine control module via a sensor to detect/confirm the first position of the axially movable structure when the recess and the outer wall are aligned with the sensor in a first sensor path. The sensor is configured to transmit feedback signals (in the form of a first set of data) to the engine control module according to the structure of the barrel cam along the first sensor path. More specifically, the recess and outer wall are configured to communicate with an engine control module via a sensor to detect/confirm the first position of the axially movable structure when the recess and the outer wall are aligned with the sensor in a first sensor path.
Similarly, the control groove and the outer wall may also be configured to communicate to an engine control module via the sensor to detect/confirm the second position of the axially movable structure when control groove and the outer wall are aligned with the sensor in a second sensor path. The sensor is configured to transmit feedback signals (in the form of a second set of data) to the engine control module according to the structure of the barrel cam along the second sensor path.
Each lobe pack in the plurality of lobe packs includes a first cam lobe adjacent to a second cam lobe in the axial direction. The first cam lobe is configured to engage with the engine valve when the axially moveable structure is in the first position. Similarly, the second cam lobe is configured to engage with the engine valve when the axially moveable structure is in the second position.
In yet another embodiment of the present disclosure, an engine assembly includes an engine control module, an internal combustion engine, a camshaft assembly, an actuator and a sensor. The internal combustion engine includes a first cylinder, a second cylinder, a first valve operatively coupled to the first cylinder, and a second valve operatively coupled to the second cylinder. The camshaft assembly may be coupled to the first and second valves of the internal combustion engine. The camshaft assembly further includes a base shaft and an axially moveable structure mounted on the base shaft. The base shaft may extend along a longitudinal axis and is configured to rotate about the longitudinal axis. The axially moveable structure is configured to move between a first position and a second position on the base shaft yet the axially moveable structure is rotationally fixed to the base shaft. The aforementioned axially moveable structure includes a barrel cam having a control groove defined between an inner wall and an outer wall of the barrel cam. The control groove may define a fixed narrow groove width throughout a second region and may define an enlarged groove width which progressively varies in at least a portion of a first region of the barrel cam.
The actuator is configured to move the axially movable structure between the first and second positions via a pin of the actuator in engagement with the control groove in the barrel cam—according to an output signal from the engine control module. The sensor is configured to send a first set of data (feedback signal) to the engine control module when axial moveable structure is in the first position. The sensor is also configured to send a second set of data (feedback signal) to the engine control module when the axial moveable structure is in the second position. It is understood that a recess is defined in the outer wall of the barrel cam and is aligned with the sensor when the axially moveable structure is in the first position.
With respect to the aforementioned engine assembly, the enlarged groove width of the first region may be greater than the fixed narrow groove width of the second region. As indicated, the actuator may include at least one pin configured to move between the retracted and extended positions (where the pin engages with the control groove) in response to the output signal from the engine control module. Moreover, the axially moveable structure may further include a plurality of lobe packs which are configured to rotate synchronously with the barrel cam when the axially movable structure rotates together with the base shaft. Each lobe pack in the plurality of lobe packs includes a first cam lobe being adjacent to a second cam lobe. The first cam lobe has a first maximum lobe height, the second cam lobe has a second maximum lobe height, and the first maximum lobe height is different from the second maximum lobe height.
The present disclosure and its particular features and advantages will become more apparent from the following detailed description considered with reference to the accompanying drawings.
These and other features and advantages of the present disclosure will be apparent from the following detailed description, best mode, claims, and accompanying drawings in which:
Like reference numerals refer to like parts throughout the description of several views of the drawings.
DETAILED DESCRIPTIONReference will now be made in detail to presently preferred compositions, embodiments and methods of the present disclosure, which constitute the best modes of practicing the present disclosure presently known to the inventors. The figures are not necessarily to scale. However, it is to be understood that the disclosed embodiments are merely exemplary of the present disclosure that may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for any aspect of the present disclosure and/or as a representative basis for teaching one skilled in the art to variously employ the present disclosure.
Except in the examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the present disclosure. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary: percent, “parts of,” and ratio values are by weight; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the present disclosure implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation; and, unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.
It is also to be understood that this present disclosure is not limited to the specific embodiments and methods described below, as specific components and/or conditions may, of course, vary. Furthermore, the terminology used herein is used only for the purpose of describing particular embodiments of the present disclosure and is not intended to be limiting in any way.
It must also be noted that, as used in the specification and the appended claims, the singular form “a,” “an,” and “the” comprise plural referents unless the context clearly indicates otherwise. For example, reference to a component in the singular is intended to comprise a plurality of components.
The term “comprising” is synonymous with “including,” “having,” “containing,” or “characterized by.” These terms are inclusive and open-ended and do not exclude additional, un-recited elements or method steps.
The phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. The phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter.
The terms “comprising”, “consisting of”, and “consisting essentially of” can be alternatively used. Where one of these three terms is used, the presently disclosed and claimed subject matter can include the use of either of the other two terms.
Throughout this application, where publications are referenced, the disclosures of these publications in their entireties are hereby incorporated by reference into this application to more fully describe the state of the art to which this present disclosure pertains.
The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.
Referring to the drawings, wherein like reference numbers correspond to like or similar components throughout the several figures,
The internal combustion engine 14 includes an engine block 18 defining a plurality of cylinders 20A, 20B, 20C, and 20D. In other words, the engine block 18 includes a first cylinder 20A, a second cylinder 20B, a third cylinder 20C, and a fourth cylinder 20D. Although
In order to propel the vehicle 10, an air/fuel mixture should be introduced into the combustion chambers 22A, 22B, 22C, and 22D. To do so, the internal combustion engine 14 includes a plurality of intake ports 24 fluidly coupled to an intake manifold (not shown). In the depicted embodiment, the internal combustion engine 14 includes two intake ports 24 in fluid communication with each combustion chamber 22A, 22B, 22C, and 22D. However, the internal combustion engine 14 may include more or fewer intake ports 24 per combustion chamber 22A, 22B, 22C, and 22D. The internal combustion engine 14 includes at least one intake port 24 per cylinder 20A, 20B, 20C, 20D.
The internal combustion engine 14 further includes a plurality of intake valves 26 configured to control the flow of inlet charge through the intake ports 24. The number of intake valves 26 corresponds to the number of intake ports 24. Each intake valve 26 is at least partially disposed within a corresponding intake port 24. In particular, each intake valve 26 is configured to move along the corresponding intake port 24 between an open position and a closed position. In the open position, the intake valve 26 allows inlet charge to enter a corresponding combustion chamber 22A, 22B, 22C, or 22D via the corresponding intake port 24. Conversely, in the closed position, the intake valve 26 precludes the inlet charge from entering the corresponding combustion chamber 22A, 22B, 22C, or 22D via the intake port 24.
As discussed above, the internal combustion engine 14 can combust the air/fuel mixture once the air/fuel mixture enters the combustion chamber 22A, 22B, 22C, or 22D. For example, the internal combustion engine 14 can combust the air/fuel mixture in the combustion chamber 22A, 22B, 22C, or 22D using an ignition system (not shown). This combustion generates exhaust gases. To expel these exhaust gases, the internal combustion engine 14 defines a plurality of exhaust ports 28. The exhaust ports 28 are in fluid communication with the combustion chambers 22A, 22B, 22C, or 22D. In the depicted embodiment, two exhaust ports 28 are in fluid communication with each combustion chamber 22A, 22B, 22C, or 22D. However, more or fewer exhaust ports 28 may be fluidly coupled to each combustion chamber 22A, 226, 22C, or 22D. The internal combustion engine 14 includes at least one exhaust port 28 per cylinder 20A, 20B, 20C, or 20D.
The internal combustion engine 14 further includes a plurality of exhaust valves 30 in fluid communication with the combustion chambers 22A, 22B, 22C, or 22D. Each exhaust valve 30 is at least partially disposed within a corresponding exhaust port 28. In particular, each exhaust valve 30 is configured to move along the corresponding exhaust port 28 between an open position and a closed position. In the open position, the exhaust valve 30 allows the exhaust gases to escape the corresponding combustion chamber 22A, 228, 22C, or 22D via the corresponding exhaust port 28. The vehicle 10 may include an exhaust system (not shown) configured to receive and treat exhaust gases from the internal combustion engine 14. In the closed position, the exhaust valve 30 precludes the exhaust gases from exiting the corresponding combustion chamber 22A, 22B, 22C, or 22D via the corresponding exhaust port 28.
As discussed in detail below, intake valve 26 and exhaust valve 30 (
With further reference to
Referring now to
With reference back to
Referring now to
The camshaft assembly 33 may further include a sensor 52 configured to align with the axially moveable structure 44 along a first sensor path 88 (
The engine control module 16 of
Similarly, the control groove 60 and the outer wall 90 may also be configured to communicate to the engine control module 16 via the sensor 52 to detect/confirm the second position 77 of the axially movable structure 44 when control groove 60 and the outer wall 90 are aligned with the sensor 52 in a second sensor path 86. (See
As shown in
In yet another embodiment of the present disclosure shown in
With reference to
With respect to the example barrel cam 56 of
Specifically referring to the example shown in
In the example shown in
As shown in
Aside from determining or confirming the axial movement of the axially moveable structure 44 when the structure 44 is in the first position 75, the algorithm 25 in the control module 16 also requires data (via feedback signals 79 from the sensor) to determine/confirm the rotational position of the axially moveable structure 44 and its corresponding lobe packs (rotational position of the lobes which are engaging with the valve). Given that the recess 92 and outer wall 90 are in a fixed angular position relative to the cam lobes, the control module 16 (and its associated algorithm) is also able to determine or confirm the exact rotational position of the lobes 54B which are engaging with the valves 66 when the axially moveable structure(s) 44 are in the first position.
Each axially movable structure 44 may be a monolithic structure. Accordingly, the lobe packs 46A, 46B, 46C, 46D and the barrel cam 56 of the same axially movable structure 44 can move/rotate simultaneously relative to the base shaft 35. Though the drawings show that each axially movable structure 44 includes four lobe packs 46A, 46B, 46C, 46D, it is understood that each axially movable structure 44 may include more or fewer lobe packs.
With specific reference to
When the feedback signals 79 (second set of data 83) match/matches the expected pattern for the second position 77, the control module 16 is able to accurately confirm or determine that the axially moveable structure 44 is, in fact, in the second position 77 (
The algorithm in the control module 16 also may also require data (via feedback signals 79 from the sensor) to determine/confirm the rotational position of the axially moveable structure and its corresponding lobe packs (rotational position of the lobes which are engaging with the valve) when the axially moveable structure is in the second position 77. The control module 16 (and its associated algorithm) is also able to determine or confirm the exact rotational position of the lobes 54B which are engaging with the valves 66 when the axially moveable structure(s) 44 are in the second position given that the control module knows: (1) the fixed angular position of the control groove 60 and outer wall 90 relative to the cam lobe 54A (which engages with valve 66) in the second position; and (2) the exact rotational position of the control groove 60 and outer wall 90 (via the feedback signals 79 from sensor 52).
Therefore, in all embodiments of the present disclosure, the cam barrel 56 includes an outer wall 90 wherein the outer wall 90 includes a groove wall surface 98 (forming part of control groove 60), an upper surface 100 and a lateral surface 102 (see
It is understood that second sensor path 86 may vary along axis X, 37 as shown by tolerance stack up (element 42) in
The control module 16 and/or sensor is configured detect the absence of the material (in the form of the enlarged control groove width 70) along second sensor path 86 in (see
With respect to the example actuators of
It is understood that the axially movable structure 44 is axially movable relative to the base shaft 35 from a first position 75 (
As noted, each lobe pack 46A-46D in plurality of lobe pack 46A, 46B, 46C, 46D in the axially movable structure 44 includes a plurality of cam lobes 54A, 54B. The barrel cam 56 in the axially movable structure 44 defines a control groove 60 defined by at least one path 61 around a circumference 63 of the barrel cam 56 such that the at least one path 61 is defined by a first region 67 and a second region 69. The actuator 34A, 34B including an actuator body 62A, 62B together with first and second pins 64A, 64B which are each movably coupled to the actuator body 62A, 62B such that each of the first and second pins 64A, 64B is movable relative to the actuator body 62A, 62B between a retracted position 71 and an extended position 73. The first and second pins 64A, 64B are configured to ride along at least one path 61 defined by the control groove 60. However, the axially movable structure 44 is axially movable relative to the base shaft 35 from a first position (
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the disclosure as set forth in the appended claims and the legal equivalents thereof.
Claims
1. A camshaft assembly comprising:
- a base shaft extending along a longitudinal axis;
- an axially movable structure mounted on the base shaft and being axially movable relative to the base shaft between a first position and a second position via an actuator while also being rotationally fixed to the base shaft, the axially movable structure includes: a plurality of lobe packs, each of the plurality of lobe packs including a plurality of
- cam lobes; and a barrel cam having a control groove defined between an inner wall and an outer wall of the barrel cam such that the control groove further includes a first region having a fixed narrow groove width between the inner and outer walls and a second region having an enlarged groove width between the inner wall and the outer walls; and a recess is defined in the outer wall of the barrel cam such that the recess is disposed adjacent to the first region; wherein the recess is defined in the first region of the barrel cam, and wherein the fixed narrow groove and the enlarged groove are aligned circumferentially around the longitudinal axis at an axial position, such that the control groove does not circumferentially overlap with itself.
2. The camshaft assembly of claim 1 further comprising a sensor configured to align with the axially moveable structure along a first sensor path when the axially moveable structure moves to the first position, and the sensor is configured to align with the axially moveable structure along a second sensor path when the axially moveable structure moves to the second position.
3. The camshaft assembly as defined in claim 2 wherein the first sensor path overlays the outer wall and the recess defined in the outer wall.
4. The camshaft assembly as defined in claim 3 wherein the second sensor path overlays the control groove and the outer wall.
5. The camshaft assembly of claim 4, further comprising a control module in communication with the actuator and the sensor.
6. The camshaft assembly of claim 5, wherein each lobe pack in the plurality of lobe packs includes a first cam lobe adjacent to a second cam lobe.
7. The camshaft assembly of claim 6, wherein the first cam lobe is configured to engage with an engine valve when the axially moveable structure is in the first position.
8. The camshaft assembly of claim 7 wherein the recess and outer wall are configured to communicate to an engine control module via the sensor to detect the first position of the axially movable structure when the recess and the outer wall are aligned with the sensor in a first sensor path.
9. The camshaft assembly of claim 8 wherein the control groove and the outer wall are configured to communicate to an engine control module via the sensor to detect the second position of the axially movable structure when control groove and the outer wall are aligned with the sensor in a second sensor path.
10. An engine assembly, comprising:
- an internal combustion engine including a first cylinder, a second cylinder, a first valve operatively coupled to the first cylinder, and a second valve operatively coupled to the second cylinder;
- an engine control module;
- a camshaft assembly operatively coupled to the first and second valves, wherein the camshaft assembly includes: a base shaft extending along a longitudinal axis, the base shaft being configured to rotate about the longitudinal axis; an axially movable structure being axially movable between a first position and a second position on the base shaft and being rotationally fixed to the base shaft, wherein the axially movable structure further includes; a barrel cam having a control groove defined between an inner wall and an outer wall of the barrel cam, the control groove defining a fixed narrow groove width throughout a first region and an enlarged groove width which progressively varies in at least a portion of a second region of the barrel cam, wherein the fixed narrow groove and the enlarged groove are aligned circumferentially around the longitudinal axis at an axial position, such that the control groove does not circumferentially overlap with itself; and an actuator configured to move the axially movable structure between the first and second positions via the control groove in the barrel cam according to an output signal from the engine control module; and a sensor configured to send a first set of data to the engine control module when the axial moveable structure is a first position and configured to send a second set of data to the engine control module when the axial moveable structure is in the second position, wherein a recess is defined in the outer wall of the barrel cam and is aligned with the sensor when the axially moveable structure is in the first position.
11. The engine assembly of claim 10 wherein the enlarged groove width of the second region is greater than the fixed narrow groove width of the first region.
12. The engine assembly of claim 11, wherein the axially moveable structure further includes a plurality of lobe packs which are configured to rotate synchronously with the barrel cam when the axially movable structure rotates together with the base shaft.
13. The engine assembly of claim 12, wherein the actuator includes at least one pin configured to move between a retracted and extended positions in response to the output signal from the engine control module.
14. The engine assembly of claim 13, wherein each lobe pack in the plurality of lobe packs includes a first cam lobe being adjacent to a second cam lobe.
15. The engine assembly of claim 14 wherein the first cam lobe has a first maximum lobe height, the second cam lobe has a second maximum lobe height, and the first maximum lobe height is different from the second maximum lobe height.
Type: Application
Filed: Jan 17, 2019
Publication Date: Jul 23, 2020
Inventors: Hong Wai Nguyen (Troy, MI), Domenic Certo (Niagara Falls), Bradley R. Kaan (Oxford, MI), Joseph J. Moon (BEVERLY HILLS, MI)
Application Number: 16/250,591