The present disclosure relates to engine camshaft assemblies.
This section provides background information related to the present disclosure which is not necessarily prior art.
Engines typically include a camshaft to actuate intake and exhaust valves. Some camshafts are concentric camshafts that provide for relative rotation between, for example, the intake and exhaust lobes. The intake lobes may be fixed to an outer shaft for rotation with the shaft and the exhaust lobes may be rotatably supported on the shaft. Alternatively, the exhaust lobes may be fixed to the outer shaft for rotation with the shaft and the intake lobes may be rotatably supported on the shaft. In any arrangement, the lobes that are rotatably supported on the outer shaft may be rotationally fixed to the inner shaft using a fastener. Insertion of these fasteners may apply a radial load to the camshaft during assembly.
This section provides a general summary of the disclosure, and is not comprehensive of its full scope or all of its features.
A method of assembling a camshaft may include locating a first lobe member of the camshaft on a first shaft and inserting a locking pin into a first bore in the first lobe member and into a second bore in the first shaft. The locking pin may include a first recess extending into a first end thereof defining a first annular wall. A first retaining member may be forced into the first recess. The forcing may displace the annular wall in an outward radial direction and into a frictional engagement with the first bore.
The method may further include forcing a second retaining member into a second recess located in a second end of the locking pin generally opposite the first end. The first retaining member may be forced into the first recess simultaneously with the second retaining member being forced into the second recess.
The camshaft assembly may include a first shaft including a first radial bore, a first lobe member located on the first shaft and including a second radial bore aligned with the first radial bore, and a locking pin located within the first and second radial bores. The locking pin may include first and second longitudinal ends generally opposite one another. The first longitudinal end may include a first recess extending axially therein and a first retaining member located within the first recess. The first retaining member may bias an annular wall defined by the first recess in an outward radial direction into a frictional engagement with a first portion of the second radial bore.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Examples of the present disclosure will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
Referring now to
The intake valve lift mechanism 22 may include a pushrod 30 and a rocker arm 32. The exhaust valve lift mechanism 24 may additionally include a pushrod 30 and a rocker arm 32. Pushrods 30 may be engaged with the camshaft 26 to actuate the rocker arms 32 and selectively open the intake and exhaust valves 18, 20. While the engine assembly 10 is illustrated as a pushrod engine, it is understood that the present disclosure is not limited to pushrod engines and may be applicable to a variety of other engine configurations as well, such as overhead cam engines.
With reference to
The first shaft 34 may include an annular wall 64 defining an inner bore 66. The second shaft 36 may be rotatably disposed within the inner bore 66 of the first shaft 34. The first shaft 34 may include slots 68 (seen in
The first set of lobe members 38, 40, 42, 44, 46 may be fixed for rotation with the first shaft 34. The engagement between the first set of lobe members 38, 40, 42, 44, 46 and the first shaft 34 may include a friction fit engagement. The second set of lobe members 48, 50, 52, 54 may be disposed between adjacent ones of the first set of lobe members 38, 40, 42, 44, 46. The second set of lobe members 48, 50, 52, 54 may be rotatably disposed on the first shaft 34 and fixed for rotation with the second shaft 36 by the fasteners 56.
As seen in
The first retaining member 74 may be located in the first recess 80 and the second retaining member 76 may be located in the second recess 84. The first and second retaining members 74, 76 may fix the locking pin 72 to one of the lobe members 48, 50, 52, 54. By way of non-limiting example, each of the first and second retaining members 74, 76 may be in the form of a generally spherical member.
First and second tools 92, 94 may be used to fix the first and second retaining members 74, 76 within the first and second recesses 80, 84. The locking pin 72 may have an outer diameter (DL) that is less than the diameter (DC) of the bore 96 extending through the lobe member 48, less than the width (DS1) of the slot 68 in the first shaft 34, and less than the diameter (DS2) of the aperture 70 in the second shaft 36. Therefore, the locking pin 72 may be placed within the bore 96, the slot 68, and the aperture 70 with little frictional resistance.
The first tool 92 may force the first retaining member 74 in a first axial direction (Al) into the first recess 80. An end of the first recess 78 may form an axial end stop for the first retaining member 74. As seen in
Similarly, the second tool 94 may force the second retaining member 76 into the second recess 84. It is understood that the relationship between the second retaining member 76 and the second recess 84 may be generally similar to the first retaining member 74 and the first recess 78 described above. However, the second retaining member 76 may be displaced in a second axial direction (A2) generally opposite the first axial direction (A1).
The frictional engagement created by the displacement of the first and second retaining members 74, 76 may generate forces on the camshaft 26 during assembly. More specifically, the installation of the first retaining member 74 may generate a first force (F1) in the first axial direction (A1) and the installation of the second retaining member 76 may generate a second force (F2) in the second axial direction (A2). The first and second forces (F1, F2) may be applied in axial directions (A1, A2) relative to the locking pin 72 and in radial directions relative to the first and second shafts 34, 36. Further, the first and second forces (F1, F2) may be equal to one another in opposite directions, producing a net force of approximately zero. Therefore, the first and second retaining members 74, 76 may be installed in the locking pin 72 simultaneously to reduce a bending force applied to the first and second shafts 34, 36.
It is understood that the fastener 56 is shown in combination with the lobe member 48 in