Patent Application
20150377094
The present disclosure relates to a detent assembly and a method of assembling the detent assembly.
Some vehicles have an internal combustion engine that combusts a mixture of air and fuel within one or more combustion chambers to produce a mechanical output. The internal combustion engine can include a sliding camshaft that controls how much the valves in the engine are opened, which controls the fuel/air mixture that is combusted to produce the mechanical output.
The sliding camshaft includes a camshaft lobe that is slidable over a base shaft. The base shaft defines a hole that receives a spring before the camshaft lobe is slid over the base shaft. After the spring is placed into the hole, a ball is disposed over the spring and a tool is utilized to press the ball into the hole to compress the spring. As the tool maintains the position of the ball in the hole, the camshaft lobe is slid over the base shaft. Once the camshaft lobe is in the desired position over the base shaft, the tool can be removed. The spring and the ball are completely separate components and positioning these components relative to each other, and utilizing the tool, can be cumbersome.
The present disclosure provides a detent assembly including a first shaft rotatable about a longitudinal axis and having an outer surface. The first shaft defines a cavity having an opening defined by the outer surface. The detent assembly further includes a camshaft defining an aperture along the longitudinal axis to present an inner wall of the camshaft that circumscribes the longitudinal axis. The inner wall defines a plurality of recesses spaced from each other. The detent assembly also includes a self-contained plunger unit that is secured to the first shaft in the cavity as a unit. A plunger of the self-contained plunger unit engages the inner wall as the camshaft is disposed over the self-contained plunger unit so that the plunger rests in one of the recesses of the camshaft to selectively secure together the first shaft and the camshaft.
The present disclosure also provides a method of assembling a detent assembly. A self-contained plunger unit is secured to a first shaft in a cavity of the first shaft, with the self-contained plunger unit including a plunger. A camshaft is disposed over the first shaft and the plunger biases against an inner wall of the camshaft as the camshaft is disposed over the first shaft. The plunger rests in one of a plurality of recesses of the inner wall of the camshaft to selectively secure together the first shaft and the camshaft.
Utilizing the self-contained plunger unit of the detent assembly eliminates the need for the tool as discussed in the background section. Eliminating the tool can simplify assembly of the components and can reduce assembly time. Also, utilizing the self-contained plunger unit of the detent assembly can ensure repeatability of placement of the plunger.
The detailed description and the drawings or Figures are supportive and descriptive of the disclosure, but the scope of the disclosure is defined solely by the claims. While some of the best modes and other embodiments for carrying out the claims have been described in detail, various alternative designs and embodiments exist for practicing the disclosure defined in the appended claims.
Those having ordinary skill in the art will recognize that terms such as “above”, “below”, “upward”, “up”, “downward”, “down”, “top”, “bottom”, “left”, “right”, “back”, “forth”, etc., are used descriptively for the figures, and do not represent limitations on the scope of the disclosure, as defined by the appended claims.
Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, an engine 10 for a vehicle is generally shown in
The vehicle can be an automotive vehicle, such as, a car, a truck, etc. It is to be appreciated that the vehicle can alternatively be a non-automotive vehicle, such as, a farm vehicle, a marine vehicle, an aviation vehicle, etc. The engine 10 can be an internal combustion engine that combusts a mixture of air and fuel within one or more combustion chambers to produce a mechanical output. It is to be appreciated that the engine 10 can be any suitable engine that can utilize the detent assembly 12 described herein. The engine 10 can include a crankshaft, a plurality of valves 14, a camshaft 16, a plurality of pistons, a plurality of pushrods, a plurality of rocker arms 18, an actuator 20, and various other components to create the mechanical output.
The engine 10 can utilize the detent assembly 12. Referring to
Turning to
Referring to
Furthermore, the camshaft 16 is selectively movable back and forth over the first shaft 22, i.e., movable along the longitudinal axis 24, which controls the rotational angle of the rocker arms 18, and the rotational angle of the rocker arms 18 controls the position of the valves 14. Specifically, the amount that the valves 14 are opened controls the fuel/air mixture that is combusted to produce the mechanical output.
Referring to
The camshaft 16 can include a plurality of cams 34 (see
Continuing with
Again, continuing with
The self-contained plunger unit 42 can include a housing 46 secured to the first shaft 22 in the cavity 28 and a biasing member 48 contained in the housing 46. The self-contained plunger unit 42, and more specifically, the housing 46 can be secured to the first shaft 22 in the cavity 28 by any suitable method, such as for example, a friction fit, an interference fit, a press fit, a slip fit, adhesive, etc.
The plunger 44 is movably coupled to the housing 46 and continuously biased outwardly away from the longitudinal axis 24 by the biasing member 48. A portion of the plunger 44 protrudes outwardly beyond the outer surface 26 of the first shaft 22 away from the longitudinal axis 24 when the inner wall 32 is spaced from the self-contained plunger unit 42 (see
The plunger 44 and the biasing member 48 are preassembled with the housing 46 to define the self-contained plunger unit 42. Therefore, the entire unit 42 is disposed in the cavity 28 of the first shaft 22 at one time, which reduces the number of parts to be assembled, and thus, reduces assembly time. Also, utilizing the self-contained plunger unit 42 simplifies assembly and ensures repeatability of the placement of the plunger 44. Furthermore, the space or clearance between the inner wall 32 of the camshaft 16 and the outer surface 26 of the first shaft 22 can be reduced because these components do not have to be designed to fit the tool (as discussed in the background section) therebetween. Therefore, the thickness of the first shaft 22 and/or the camshaft 16 can be increased by utilizing this detent assembly 12 which can improve the stiffness of the first shaft 22 and/or the camshaft 16.
The plunger 44 is continuously biasing outwardly by the biasing member 48 such that the plunger 44 engages the inner wall 32 as the camshaft 16 is disposed over the plunger 44. Specifically, the plunger 44 is biasable back and forth relative to the housing 46 as the camshaft 16 moves back and forth along the longitudinal axis 24 over the plunger 44. Specifically, the plunger 44 moves radially back and forth relative to the longitudinal axis 24 while the camshaft 16 moves axially back and forth relative to the longitudinal axis 24. Simply stated, the plunger 44 can retract and extend. The plunger 44 rests in one of the recesses 40 of the camshaft 16 to secure together the first shaft 22 and the camshaft 16. Specifically, the plunger 44 selectively secures the camshaft 16 in an axial position relative to the first shaft 22. Moving the camshaft 16 along the longitudinal axis 24 changes the position of the cams 34 relative to respective rocker arms 18, which rotates the rocker arms 18 to another angular position, and thus, how much the valves 14 are open/close. When the plunger 44 is inserted into the aperture 30 of the camshaft 16, the camshaft 16 and the first shaft 22 become splined together such that the camshaft 16 and the first shaft 22 rotate in unison or concurrently about the longitudinal axis 24.
For example, when there are three recesses 40, the plunger 44 can secure the camshaft 16 in three different positions relative to the first shaft 22 along the longitudinal axis 24. Axial movement of the camshaft 16 causes the plunger 44 to rest in one of the recesses 40 and does not affect the camshaft 16 and the first shaft 22 being splined together during operation of the engine 10. In other words, once assembled, the camshaft 16 and the first shaft 22 remain splined together to rotate in unison even when the camshaft 16 moves axially along the longitudinal axis 24 such that the plunger 44 rests in a different recess 40. Depending on which of the three recesses 40 the plunger 44 is disposed in, the valve 14 can be in a high lift position, a low lift position or a no lift position, each of which changes how much the valves 14 are opened. As discussed above, more or less recesses 40 can be utilized depending on how many positions are desired to open/close the valves 14.
The self-contained plunger unit 42 can be any suitable configuration and two suitable examples are shown in the Figures. Specifically,
Referring to
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Continuing with
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Turning to
Turning to
Turning back to
The camshaft 16 can include a plurality of second ramps 74 adjacent to respective recesses 40 to allow the plunger 44 to move back and forth, i.e., retract and extend, into one of the recesses 40 as the camshaft 16 moves along the longitudinal axis 24. One of the second ramps 74 cooperates with the first ramp 72 to allow the plunger 44 to move from the first ramp 72 to the second ramp 74.
The plunger 44 is disposed in one of the recesses 40 to selectively secure the axial position of the camshaft 16 and the cams 34 relative to the first shaft 22. When in the assembled position, the plunger 44 is biased outwardly beyond the outer surface 26 of the first shaft 22 into one of the recesses 40. The biasing member 48 can be configured to apply the desired amount of radial force to the plunger 44, which applies the desired amount of radial force to the inner wall 32 of the camshaft 16 in the recess 40 to secure together the camshaft 16 and the first shaft 22. The radial force is applied by the biasing member 48 radially relative to the longitudinal axis 24, i.e., transverse to the longitudinal axis 24. An axial force is applied to the camshaft 16 to move the camshaft 16 along the longitudinal axis 24 and this axial force overcomes the radial force which allows the plunger 44 to move back and forth into different recesses 40. The radial force applied to the inner wall 32 in the recess 40 is large enough to maintain the desired position of the camshaft 16 relative to the first shaft 22 during operation of the engine 10.
When the camshaft 16 moves along the longitudinal axis 24 toward the self-contained plunger unit 42, the plunger 44, and more specifically, the engagement end 66 engages the first ramp 72 which causes the plunger 44 to move back into the chamber 50, i.e., retract, and as the camshaft 16 continues to move along the longitudinal axis 24, the plunger 44 moves forward, i.e., extends, as the engagement end 66 engages the second ramp 74 until the plunger 44 rests in the recess 40. If another recess 40 is desired, the plunger 44 moves back and forth along the next second ramp(s) 74 until the plunger 44 rests in the next recess 40, and so on until the desired position of the camshaft 16 is reached. Therefore, the plunger 44 and the recesses 40 cooperate to maintain the desired axial position of the camshaft 16 relative to the first shaft 22.
Referring to
At block 102, the self-contained plunger unit 42 is secured to the first shaft 22 in the cavity 28 of the first shaft 22. In certain embodiments, securing the self-contained plunger unit 42 to the first shaft 22 further includes securing the housing 46 of the self-contained plunger unit 42 to the first shaft 22 in the cavity 28. As discussed above, the self-contained plunger unit 42 includes the plunger 44.
At block 104, the camshaft 16 is disposed over the first shaft 22. In certain embodiments, disposing the camshaft 16 over the first shaft 22 further includes disposing the first shaft 22 through the aperture 30 of the camshaft 16. Disposing the camshaft 16 over the first shaft 22 can further including moving the camshaft 16 over the first shaft 22. Therefore, the camshaft 16 can be slid over the first shaft 22 such that the first shaft 22 is inserted into the aperture 30. Simply stated, the first shaft 22 can be slid into the aperture 30 of the camshaft 16. The camshaft 16 is spaced from the self-contained plunger unit 42 when the camshaft 16 is initially disposed over the first shaft 22, i.e., in the preassembled position.
At block 106, the plunger 44 is biased against the inner wall 32 of the camshaft 16 as the camshaft 16 is disposed over the first shaft 22. Therefore, as the camshaft 16 continues to be disposed over the first shaft 22, the self-contained plunger unit 42 is inserted into the aperture 30 of the camshaft 16 such that the plunger 44 engages with the inner wall 32. Specifically, the plunger 44 engages the first ramp 72 at the first end 70 of the camshaft 16 as the camshaft 16 continues to move over the first shaft 22. Then the plunger 44 engages the second ramp 74 as the camshaft 16 continues to be disposed or moved over the first shaft 22. Even more specifically, the engagement end 66 of the plunger 44 engages the first ramp 72 and the second ramp 74.
At block 108, the plunger 44 rests in one of the plurality of recesses 40 of the inner wall 32 of the camshaft 16 to selectively secure together the first shaft 22 and the camshaft 16. Therefore, the camshaft 16 continues to be disposed over the first shaft 22 until the plunger 44 is positioned into the desired recess 40. When the plunger 44 rests in the desired recess 40, the camshaft 16 is secured to the first shaft 22 in the axial position, i.e., along the longitudinal axis 24. In other words, the camshaft 16 will remain in the axial position relative to the first shaft 22 until the axial force overcomes the radial force applied by the plunger 44 which causes the plunger 44 to move and allows the camshaft to move along the longitudinal axis 24 to another axial position relative to the first shaft 22.
The first shaft 22 and the camshaft 16 can rotate in unison when the plunger 44 rests or is positioned in one of the recesses 40. Specifically, the first shaft 22 and the camshaft 16 are splined together to rotate about the longitudinal axis 24 in unison. The splined engagement between the first shaft 22 and the camshaft 16 is configured such that the camshaft 16 can move axially relative to the first shaft 22 between recesses 40 while maintaining this splined connection.
At block 110, the plunger 44 is continuously biased outwardly by the biasing member 48 of the self-contained plunger unit 42 while the plunger 44 remains movably coupled to the housing 46. Therefore, the plunger 44 is continuously biased outwardly before and after securing the camshaft 16 and the first shaft 22 together. As such, the plunger 44 is movable back and forth relative to the housing 46 due to the biasing member 48.
It is to be appreciated that the order or sequence of performing the method 100 as identified in the flowchart of
While the best modes for carrying out the disclosure have been described in detail, those familiar with the art to which this disclosure relates will recognize various alternative designs and embodiments for practicing the disclosure within the scope of the appended claims. Furthermore, the embodiments shown in the drawings or the characteristics of various embodiments mentioned in the present description are not necessarily to be understood as embodiments independent of each other. Rather, it is possible that each of the characteristics described in one of the examples of an embodiment can be combined with one or a plurality of other desired characteristics from other embodiments, resulting in other embodiments not described in words or by reference to the drawings. Accordingly, such other embodiments fall within the framework of the scope of the appended claims.
