Camshaft for reciprocating piston engines

Abstract

Axially spaced cams and bearing rings mounted on a tube are permanently secured to the tube by circumferentially spaced projections on the tube extending into grooves formed on the inside surfaces of the cams and bearing rings.

Description

andtube tool 36 has been moved axially through the bearing ring 14 and the cam 12. Of course, to completely make the camshaft, the operation will be completed after the expander tool 36 has moved through the cam 10 as shown in FIG. 7. A plurality of circumferentially separated semi-spherically shaped hard material protrusions 28 are embedded in the expander tool 36 adjacent one end of the expander tool 36. The effective diameter of the protrusions 28 is sufficiently larger than the inside diameter of the tube 13 to cause the protrusions to expand portions of the tube 13 into the cam grooves and bearing ring grooves to permanently secure the cams and bearing ring on the tube.

As shown in FIG. 5, the semi-spherical hard material protrusions 28 are positioned so that as the protrusions move within the tube past the cam or bearing the hard material protrusions 28 will expand the softer tube material into the grooves. As a result of the expansion, the entire circumference of the tube 13 is moved outwardly. Because of the slight difference between the initial diameter of the tube 13 and the inside surfaces of the cams and bearing ring, the outside surface of the tube presses tightly against the inside surfaces of the cams and bearing ring.

The completed camshaft for reciprocating piston engines will include the rotatable tube 13 with the plurality of circumferentially spaced axially extending projections 30 (see FIG. 6) on its outside surface. The projections are, of course, formed by expanding portions of the wall of the tube away from the axis of the tube. Note that all of those portions of the wall which are displaced are expanded away from the axis of the tube so that there is no offset or displacement of the tube wall. That is, the axis of the cams and the axis of the bearing ring are the same as the axis of the remainder of the tube 13. This is in sharp contrast to the camshaft shown in the U.S. Pat. No. 4,382,390 issued May 10, 1983 to Friedrich Jordan and entitled, "Camshaft For Reciprocal Piston Engines". The projections of the tube extend into the grooves of the cams and bearing to permanently secure the cams and bearing ring on the tube.

As a specific example, the tube 13 may range from 1 inch to 11/4 inches outside diameter with a wall thickness ranging from 0.125 inches to 0.150 inches, depending on the intended use of the camshaft. For example, camshafts for automotive and diesels would be larger than for other purposes. The tube-to-cam clearance and the tube-to-bearing ring clearance ranges from 0.001 inches to 0.010 inches. The grooves in the cams and the grooves in the bearing ring may be approximately 0.020 inches deep with a radius ranging from 1/8 to 1/4 inch. The expander tool 36 would have an outside diameter of about 0.020 inches less than the inside diameter of the tube 13 with the protrusions 28 having an effective outside diameter approximately 0.080 inches larger than the inside diameter of the tube 13.

The tube 13 is preferably made of formable steel having a maximum hardness of R 40. The cams are preferably made of steel which is hardenable to a minimum hardness of R 58. Powder forged AISI 4660 series material have also been successfully used as cams. The bearing rings are preferably steels or iron compatible with the bushings. Also, powdered metal rings have been used having an apparent hardness of R_B 90.

Claims

1. A camshaft for reciprocal piston engines comprising: a rotatable and expandable tube having an axis and an annular wall; and axially spaced members including axially spaced cams and bearing rings mounted about the tube, the rotatable tube and the axially spaced members , cams, and bearings having the same axis; the rotatable tube having a plurality of circumferentially spaced projections spaced around its entire circumference and extending axially through and from one longitudinally outermost member to and through the other longitudinally outermost member, said circumferentially spaced projections being spaced apart from each other, the projections being formed by expanding circumferentially spaced portions of the wall of the tube away from the axis of the tube, each cam and each bearing ring axially spaced member having a plurality of circumferentially spaced axially extending grooves on their its inner surfaces ; surface , said circumferentially spaced grooves being spaced apart from each other, each projection of the tube extending only partially into a groove of each axially spaced member, cam and a groove of each bearing ring to permanently secure the cams and bearing rings on the tube

the annular wall of the tube characterized by expansion into contact with the inner surface of the axially spaced member, each projection of the tube characterized by expansion greater than the expansion of the annular wall of the tube between projections. 2. A camshaft as in claim 1 wherein said axially spaced members include cams.

3. A camshaft as in claim 1 wherein said axially spaced members include cams and bearing rings.