U.S. patent number RE33,888 [Application Number 07/648,844] was granted by the patent office on 1992-04-21 for method of making a camshaft for reciprocating piston engines.
This patent grant is currently assigned to The Torrington Company. Invention is credited to Jeffrey A. Clark, John P. Cook, Michael J. Hartnett, Robert Lugosi, James Rollins.
United States Patent |
RE33,888 |
Hartnett , et al. |
April 21, 1992 |
Method of making a 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.
Inventors: |
Hartnett; Michael J. (Woodbury,
CT), Lugosi; Robert (Canton, CT), Rollins; James
(Winsted, CT), Cook; John P. (Simsbury, CT), Clark;
Jeffrey A. (Harwinton, CT) |
Assignee: |
The Torrington Company
(Torrington, CT)
|
Family
ID: |
27095475 |
Appl.
No.: |
07/648,844 |
Filed: |
January 31, 1991 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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819837 |
Jan 17, 1986 |
4781076 |
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Reissue of: |
167759 |
Mar 14, 1988 |
04858295 |
Aug 22, 1989 |
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Current U.S.
Class: |
29/888.1; 74/567;
29/523 |
Current CPC
Class: |
B21D
39/14 (20130101); B21D 53/845 (20130101); F01L
1/047 (20130101); F16C 35/063 (20130101); F16D
1/072 (20130101); F16C 3/026 (20130101); F16C
3/02 (20130101); F16H 53/025 (20130101); B23P
2700/02 (20130101); Y10T 74/2101 (20150115); Y10T
29/49293 (20150115); Y10T 29/4994 (20150115); F16C
2360/18 (20130101) |
Current International
Class: |
B21D
39/08 (20060101); B21D 53/84 (20060101); B21D
39/14 (20060101); B21D 53/00 (20060101); F01L
1/047 (20060101); F16H 53/02 (20060101); F16D
1/06 (20060101); F16D 1/072 (20060101); F16C
35/063 (20060101); F16C 35/04 (20060101); F16H
53/00 (20060101); F16C 3/00 (20060101); F01L
1/04 (20060101); B23P 015/00 () |
Field of
Search: |
;29/888.1,523
;74/567 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3401057A1 |
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Jan 1983 |
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DE |
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46-21299 |
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Jun 1971 |
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JP |
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9034 |
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Jan 1981 |
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JP |
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149655 |
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Sep 1982 |
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JP |
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850058 |
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Sep 1960 |
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GB |
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1117816 |
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Jun 1968 |
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GB |
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2121908A |
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Jun 1983 |
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GB |
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2167524A |
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May 1985 |
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GB |
|
Primary Examiner: Cuda; Irene
Attorney, Agent or Firm: Minns; Michael H. Troidl; Frank
S.
Parent Case Text
This is a division of application Ser. No. 819,837 filed Jan. 17,
1986, now U.S. Pat. No. 4,781,076.
Claims
We claim:
1. A method of making a camshaft having .[.cams and bearing
rings.]. .Iadd.axially spaced members .Iaddend.on a rotatable tube
comprising the steps of:
axially spacing and placing the .[.cams and bearing rings.].
.Iadd.axially spaced members .Iaddend.about the rotatable tube,
each .[.cam and each bearing ring.]. .Iadd.axially spaced member
.Iaddend.having a cylindrical inside surface with circumferentially
spaced apart axially extending grooves on said inside surfaces;
axially aligning said grooves in said .[.cam and said bearing
rings.]. .Iadd.axially spaced members .Iaddend.on said tube;
and
expanding circumferentially spaced apart portions of the wall of
the tube away from the tube axis and into the grooves on the inside
surfaces of the .[.cams and bearing rings.]. .Iadd.axially spaced
members .Iaddend.by axially inserting an expander tool having
circumferentially separated hard material protrusions constructed
to expand portions of the wall of said tube away from the tube
axis, into the tube, each of said protrusions being positioned in
axial alignment with each of said grooves so that as the
protrusions move within the tube past the .[.cams and bearing
rings.]. .Iadd.axially spaced members .Iaddend.the hard material
protrusions expand said portions of the wall into the grooves on
the inside surfaces of the .[.cams and bearing rings.].
.Iadd.axially spaced members.Iaddend.. .Iadd.
2. The method of claim 1, wherein said axially spaced members
include cams. .Iaddend. .Iadd.3. The method of claim 1, wherein
said axially spaced members include bearing rings. .Iaddend.
Description
.Iadd.BACKGROUND OF THE INVENTION .Iaddend.
This invention relates to camshafts for reciprocating piston
engines. More particularly, this invention is a new camshaft and a
new method of making a camshaft in which bearings, cams and the
like are produced as individual parts and are fastened to the
shaft.
The U.S. Pat. No. 4,382,390, issued May 10, 1983, to Friedrich
Jordan and entitled, "Camshaft for Reciprocal Piston Engines",
shows a camshaft in which bearings, cams, and the like are produced
as individual parts and are fastened to the tube. In the Jordan
camshaft, a tube is expanded by hydraulic or rubber means to
conform the outside wall of the tube with the inside surface
geometry of the cams and bearing rings. However, a big disadvantage
in making the Jordan camshaft is that the wall and the axis of the
tube inside the cams is completely offset from the wall and the
axis of the rest of the tube. Thus, it is necessary that the cams
be inserted into a die which corresponds to their outer shape in
order to be sure that the widening of the hollow shaft will not
cause substantial deformation of the cams.
The camshaft for a reciprocating piston engine and the method of
making such a camshaft of this invention does not require that
portions of the tube wall be completely offset to an axis different
from the axis of the rest of the tube. Therefore, the forces
necessary to interlock the cams and bearing rings with the tube are
far less than the forces required by Jordan and usually the
specially formed die required by Jordan is unnecessary.
Other current methods for making camshafts in which bearings, cams,
and the like are produced as individual parts and fastened to a
tube include uniformly expanding a tube to interlock with axial
splines in the cam inside diameter. A uniform internal pressure is
applied to expand the tube to uniformly match the outside diameter
of the tube with the inside diameter of the cam. At this pressure,
the cam is not yet stressed and no tube material has flown into the
splines. In order for material to flow into the splines, the
internal pressure in the tube must be increased. At the higher
pressure, as the tube material flows into the splines, the
cylindrical inside diameter portion of the cam is stressed. The
resulting tensile stresses in the cam inside diameter tend to cause
cracks if the cam is not in the soft state of heat treatment. Even
if the cam is in the soft state, the stress situation is
undesirable and is typically countered by the application of
external pressure on the cam equivalent to that of the internal
stresses. To apply the external stressing, some means of
pressurization is set-up, such as a die or hydraulic system which
always increases costs.
The camshaft for a reciprocating piston engine and the method of
making such a camshaft of this invention require much smaller total
energy (forces). The stressing of the inside diameters of the cams
and bearings is essentially eliminated. Thus, fully hardened cams
and bearings can be readily attached to the tube at very low
cost.
.Iadd.SUMMARY OF THE INVENTION .Iaddend.
Briefly described, the camshaft comprises a rotatable tube having a
plurality of circumferentially spaced axially extending projections
on its outside surface. The projections are formed by expanding
portions of the wall of the tube away from the axis of the tube.
Axially spaced cams and bearing rings are mounted about the tube.
Each cam and each bearing ring has circumferentially spaced,
axially extending grooves on their inner surfaces The projections
of the tube extend into grooves of the cams and bearing rings to
permanently secure the cams and bearing rings on the tube.
Briefly described, the new method of making a camshaft comprises
axially spacing and placing the cams and bearing rings on the
rotatable tube. Each cam and each bearing ring has
circumferentially spaced, axially extending grooves on their inner
surfaces. Portions of the wall of the tube are expanded away from
the tube axis and into the grooves on the inner surfaces of the
cams and bearing rings.
The invention, as well as its many advantages, may be further
understood by reference to the following detailed description and
drawings in which:
.Iadd.BRIEF DESCRIPTION OF THE DRAWING FIGURES .Iaddend.
FIG. 1 is a longitudinal section showing the axially spaced cams
and bearing ring slipped over the tube;
FIG. 2 is a sectional view taken along lines 2--2 of FIG. 1 and in
the direction of the arrows;
FIG. 3 is a sectional view taken along lines 3--3 of FIG. 1 and in
the direction of the arrows;
FIG. 4 is a longitudinal section through the camshaft showing the
parts after an expander tool has moved partially through the tube
to displace longitudinal portions of the tube;
FIG. 5 is a view taken along lines 5--5 of FIG. 4 and in the
direction of the arrows; and
FIG. 6 is a sectional view, on an enlarged scale, showing the
interlocking arrangement of a tube projection into the groove of
the cam.
.Iadd.DETAILED DESCRIPTION .Iaddend.
In the various figures, like parts are referred to by like
numbers.
Referring to the drawings and more particularly to FIG. 1, the
manufacture of the camshaft is accomplished by slipping the cams 10
and 12 and bearing rings 14 (only one bearing ring shown) over the
tube 13 at the desired location. The cams and bearing rings are
axially spaced from one another and held in position in their
desired axial and radial positions.
The inside surfaces of each cam and the inside surface of the
bearing ring have inside diameters sufficiently larger than the
outside diameter of the tube 13 to provide a tube-to-cam clearance
and a tube-to-bearing ring clearance ranging from 0.001 inches to
0.010 inches. Thus the cams and the bearing ring may be easily slip
fit over the tube.
The inside surface of cam 10 and the inside surface of cam 12 have
circumferentially spaced grooves 22 and 24, respectively, axially
extending completely through the cams 10 and 12. Similarly, the
inside surface of the bearing ring 14 has circumferentially spaced
grooves 26 axially extending completely through the bearing ring
14.
To permanently secure the cams and bearing ring on the tube,
portions of the wall of the tube are expanded away from the tube
axis and into the grooves on the inside surfaces of the cams and
bearing ring. In the embodiment shown in FIGS. 4 through 6, the
portions of the tube are mechanically expanded.
As shown in FIG. 4 an expander tool 36 is shown after it has been
moved partially through the tube 13. The expander tube 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.
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 .Iadd.ranges from 0.001 inches
to 0.010 inches. The grooves in the .Iaddend.cams and the grooves
in the bearing ring may be approximately 0.020 inches deep with a
radius ranging from 1/8 inch 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.sub.B 90.
* * * * *