JP2001004009A - Cam and journal element for built-up light-weight cam shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a built-up light-weight can shaft used for internal combustion engines and another high speed machinery, by making a thin cam and a journal element by the use of a thin metal forming method and another lighting method. SOLUTION: An element 50 used for a built-up camshaft includes a cylindrical inner hollow hub member 52 having a first and a second axial end portion, an outer wall 54 having a first and a second axial end portion and spaced apart from the inner hub member 52 in the radial direction, and a web portion 53 extending between the first axial end portion of the outer wall 54 and the second axial end portion of the hub member 52, and contacting the outer wall 54 to the hub member 52. The element 50 may be used on a cam shaft as a cam or journal member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention generally relates to
More particularly, with respect to camshafts, the present invention is directed to a lightweight assembly for internal combustion engines and other high speed machines made using thin cams and journal elements made by sheet metal forming or other lightweighting techniques. For the camshaft,

[0002]

BACKGROUND OF THE INVENTION Cam elements have been used for centuries to control movement and its timing. In large stationary relatively slow devices, the cam mass and moment of inertia are less important. However, for internal combustion engines used in mobile powered equipment, the high rotational speed of the cams, as well as the fact that weight reduction in engines is generally desirable, has encouraged efforts to make lightweight camshafts economically. did.

[0003] Camshafts for internal combustion engines have previously been made from cast or forged steel workpieces that have been machined, drilled, quenched, and ground to a finished shape. They included the cam lobes and journals needed for the particular engine intended. In an effort to increase engine efficiency, reduce weight and reduce production costs, techniques have been developed for manufacturing lightweight camshafts by securing preformed cams and journal elements to hollow tubes.

Several patents have been granted for various aspects of this technology. Most of these are camshaft tubes by forming the cam and / or journal elements from castings, compacted and sintered metal powders, or forged blanks, and welding, brazing or mechanically expanding the tubes. Includes fixing to In some cases, each element is provided with holes or grooves between their hub and the outer surface to reduce weight. US Pat. No. 5,201,246 and Swiss Patent 675,006 A5 provide examples of such lightweighting techniques.

[0005] To achieve more weight reduction, others form cam and journal elements from tube sections and / or drawn sheet metal cups (eg, British Patent 275,84).
2, German Patent 3346,056 Al, Japanese Patent 60-81
569, Japanese Patent No. 60-3731, and US Pat.
246). All of these are useful in making cams with large diameter base circles and journals,
Most cannot be used for small cams and journals. The reason is that when the radial size of the base circle approaches the tube radius plus twice the material thickness, the forming strain is too severe. In those cases, the forming punch becomes too thin to withstand the required forming loads. This is illustrated in FIGS. 1-4 which show a large base circle cam element and a punch and die set of the type required to form the large and small base circle cam elements and journal elements of US Pat. No. 5,201,246. It is shown.

FIGS. 1 and 2 show a cam element "E" mounted on a hollow shaft "S". The base circle has a radius "B" from the center of the axis "S". “B” consists of the radius “R” of the shaft plus the minimum distance “Δ” from the shaft surface to the element surface.
The minimum for "Δ" is twice the thickness of the cam element plus the minimum thickness of the form bit required to form the cam element. This is shown in FIGS. 3 and 4 which show the cross sections of the die a, punch c and element b for the large and small base circles, respectively. The small base circle element cannot always be formed by a thin punch.

[0007] Thus, the economy of sheet metal forming and the degree of weight reduction achievable by using conventional cam and journal element types is achieved when the base circle exceeds the minimum base circle tolerance of the forming tool. Can only be. Thus, camshafts of current designs with small base circles can only be made using cast, forged or compressed and sintered powdered metal elements.

[0008]

The foregoing illustrates the limitations known to exist on the size of current cam and journal elements that can be manufactured by sheet metal forming. Therefore, it would be clearly beneficial to provide an alternative aimed at overcoming at least one or more of the aforementioned limitations. Therefore, suitable alternatives are provided which include the features more fully disclosed below.

[0009]

SUMMARY OF THE INVENTION In one aspect of the present invention, this includes a hollow cylindrical inner hub member having first and second shaft ends, a first and second shaft end. Have
An outer wall radially spaced from the inner hub member, a first axial end of the outer wall, and a second axial end of the hub member;
By providing a component for use in an assembled camshaft with a web portion extending between the axial ends of the hub and joining the outer wall to the hub member.

The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The present invention is illustrated by comparison with the prior art shown in FIGS. 9-17 and FIGS. 1-8. 9, 10 and 11 show three views of a large base circular cam element 50 made in accordance with the present invention. It comprises a hub member 52 having a first axial distal end "f" and a second axial proximal end "n", a first axial proximal end "p" and a second axial end. Wall 54 having a directional end "d" and a second axial proximal end "n" of the hub member 52 and the outer wall 54.
And a web portion 53 extending between and joining the first axial base ends "p" of the first and second axial ends. This configuration of the cam element allows for forming with a robust tooling as shown in FIGS. 12-17, even when the radius of the base circle "B" approaches the value of "R" plus the thickness of the element wall. ,enable. (As described above with respect to FIG. 1)

FIGS. 12 and 14 show a die 20 and a punch 10, respectively, for forming the large base circle element 30 in FIG. The element 30 has a hub member 32, an outer wall member 34 and a web portion 33 connecting the hub and the axial end of the outer wall member. Since there is no U-bend for the conventional element b of FIGS. 1-8, the severity of forming stress is much less.
Tool wear and power consumption by the press are also reduced as a result of the reduced severity of molding distortion. At least one axial groove (or ridge) 36 is attached to hub member 3.
2 may be provided along the inner surface to provide accurate orientation and torsional fixation on the hollow shaft when mating the groove and hub member during assembly of the camshaft. Of course, such torsional locking can also be provided by swaging or other techniques applied simultaneously to both the cam element and the camshaft tube during assembly of the camshaft. The torsion is fixed by the cam
Timing is required at the assembled camshaft to ensure that the timing does not change due to torsional misalignment between the cam member and the camshaft tube. This also includes welding, brazing,
This can be achieved by swaging or by any feature on the inner surface of the hub member that renders its surface non-cylindrical, eg, any polygonal shape or axial discontinuity in the inner surface of the hub member. When using a non-cylindrical hub member or a hub member having an axial discontinuity, during camshaft assembly, the camshaft tube conforms to the non-cylindrical shape of the inner surface of the hub member. It may be spread by a mandrel thereby to provide the required torsional fixation. If welding, brazing or swaging is used during assembly, non-cylindrical holes or axial discontinuities are not required in the hub member.

The same applies to the small base circle element 35 formed by the punch 15 entering the die 25 in FIGS. The element 35 comprises at least one groove 36 'having a hub member 32', an outer wall member 34 ', and a web portion 33' connecting the hub and the axial end of the wall member. It is clear that this design can be used for elements having a base circle where "Δ" is approximately equal to the wall thickness of the element. Clearly, the tooling in FIGS. 3-8 cannot be used for such elements. The reason for this is that the minimum value of "Δ" that can be achieved with such a conventional design is twice the wall thickness plus the minimum punch thickness. The simplified dies and punch sets shown in FIGS. 3-8 and 12-17 are intended to fully describe the forming bytes required to form the cam and journal elements, except for those figures. Note that we did not.

FIGS. 18 and 21 correspond to FIGS.
7 shows a cross section of a large and small base circular element 30, 35 of conventional shape made in accordance with the present invention using the tooling of FIG. In both cases, the web portions 33, 32 'are perpendicular to both the hub members 32, 32' and the outer walls 34, 34 ', and the axially proximal ends of the hub members 32, 32' extending in opposite directions. Connect. FIGS. 19 and 20 show elements where the web portions 60, 60 'are not perpendicular to the hub and outer wall members. Instead, it is tilted from the vertical. FIG.
, The hub member is displaced axially from the outer wall member, while in FIG. 20, the hub member is partially overlapped by the outer wall member. The embodiment of FIG. 19 could have been used to make the forming operation easier if axial space in the camshaft allowed, while the embodiment of FIG. Used where it needs to be restricted. Of course, the amount of overlap is the same as in the prior art, but to a lesser extent limited by the base circle diameter and the required minimum form bit thickness.

FIGS. 22 and 23 show prior art lightweight camming elements formed by conventional forming techniques (eg, forging, casting or powder metallurgy). Although this is a good design, the tight spacing between the hub "H" and the outer wall at "X" on both sides of the element requires thin tools that are susceptible to excessive wear and damage. In some cases, the web portion
Holes can be drilled to further reduce weight (not shown)
Sometimes. This design also provided a hub "h" and an axially centered web portion "W" at the outer wall so that the recess was split into two axially separated portions (shown). Zu).

FIGS. 24 and 25 show a cam element 40 of the present invention further having a base circle having a radius equal to the radius of the tube to which it will be mounted plus the thickness of the outer wall 34 ".
Is shown in another embodiment. This cam element can be formed from sheet metal as described above or by conventional forming techniques. In this case, tooling can be made stronger by removing the reentrant hub portion "h" in the element, and the final element is light, regardless of the molding method used. This element is in full contact with the tube when the outer wall portion 34 "of the base circle is installed, so that the hub 3
Note that despite the short axial dimension of 2 ", it does not tend to tilt.

FIG. 26 shows the element 50 with an outer wall 54 joined to the axial center of the hub member 52 at the first axial end of the element by a web 53. The hub member 52 is formed by squeezing into a cup-like shape with a concave bottom, then piercing to locally thicken the web 53, and widening the pierced hole. This provides sufficient axial depth for stability and tilt resistance after assembly into the camshaft tube. This embodiment may be used instead of the one in FIG. 10 when it is most necessary to limit the axial space.

The assembly element shown in FIG. 27 is another embodiment that can be made using simpler tooling and less stringent molding. It's web 7
Consisting of an outer wall 74 formed as a single piece with three,
The web is sized so that the holes fit into the camshaft tube. Hub member 72 (cut from the tube) is welded or brazed to web 73 surrounding the hole.
This embodiment may also be used for low cost experimental samples, as well as when the required material is particularly difficult to form by normal molding operations. FIG. 18, 1
9 and 25 are radially extending reinforcing lips 38, 3 for three embodiments of the illustrated element, respectively.
8 ', 38 ". It is formed by rolling the edge of the distal end of the outer wall of the element after the drawing operation, which greatly increases the stiffness and rigidity of the element. Only shown in FIGS. 18, 19 and 25, the present invention is shown in all figures to increase the radial load bearing capacity, thereby enabling the use of lighter standard materials for the elements. Applicable to all embodiments.In addition to this feature, power consumption and tool wear are also reduced by allowing the use of lighter standard materials. In the case of an element having a base circle having a radius approximately equal to the radius of the outer wall of the element plus the thickness of the outer wall of the element, the reinforcing lip 38 "when assembled will not contact the outer wall 34" which does not directly contact the camshaft tube.
May be provided only in that part.

Further weight savings of the cam and journal elements of the present invention are also provided by the web portions 33, 33 ', 33 ", as was done in some prior art cam elements.
And 53 may be achieved by drilling holes.

A major obstacle to forming the small base circular cam and journal elements has been the inability to form a hub member within the axial dimension of the outer wall. This is because, as mentioned above, if the base circle is too small, the forming punch will be too weak and brittle to accomplish the forming operation. Thus, the smallest base circle possible with conventional designs has a radius approximately equal to the camshaft tube radius plus four times the element wall thickness.

The present invention overcomes that obstacle by eliminating the U-bend required by conventional designs and thus allowing the use of heavier and stronger molding punches. In addition to allowing the formation of small base circular cam elements and journal elements having a radius equal to the camshaft tube radius plus twice the element thickness, the design of the element of the present invention is based on the element wall. Makes it possible to mold an element with a base circle radius equal to the camshaft tube radius plus only a single thickness of.

[Brief description of the drawings]

FIG. 1 shows a vertical end view of a large basic circular cam element of the prior art.

FIG. 2 is a sectional elevation view of the cam element taken along line 2-2 of FIG.

FIG. 3 shows a cross section of a die for a large basic circle element of the prior art.

FIG. 4 shows a sectional view of a cam or journal element for a large basic circle element of the prior art.

FIG. 5 shows a cross section of a punch for a large basic circle element of the prior art.

FIG. 6 shows a sectional view of a die for small basic circle elements.

FIG. 7 shows a sectional view of a cam or journal element for a small base circle element.

FIG. 8 shows a cross-sectional view of a punch for a small basic circle element.

FIG. 9 is a perspective view of a cam element of the present invention.

FIG. 10 is a side elevation view of the cam element of the present invention.

FIG. 11 is an end view of the cam element of the present invention.

FIG. 12 shows a sectional view of a die.

FIG. 13 shows a sectional view of a large basic circle element of the present invention.

FIG. 14 shows a sectional view of a punch for forming an element.

FIG. 15 shows a cross-sectional view of a die.

FIG. 16 shows a sectional view of a small base circle element of the present invention.

FIG. 17 shows a cross section of a punch for forming an element.

FIG. 18 illustrates one embodiment of an element of the invention.

FIG. 19 illustrates another embodiment of an element of the invention.

FIG. 20 illustrates yet another embodiment of an element of the invention.

FIG. 21 illustrates yet another embodiment of an element of the invention.

FIG. 22 is an axial end view of a cam element having a small base circle manufactured by another conventional lightening technique.

FIG. 23 is a longitudinal cross-sectional view of a cam element having a small base circle manufactured by another conventional lightening technique.

FIG. 24 is an axial end view of another embodiment of a small base circular cam element made in accordance with the present invention.

FIG. 25 is a longitudinal cross-sectional view of another embodiment of a small base circular cam element made in accordance with the present invention.

FIG. 26 is a longitudinal sectional view of another embodiment of the cam element of the present invention. as well as

FIG. 27 is a longitudinal sectional view of the assembled cam element of the present invention.

[Explanation of symbols]

 Reference Signs List 10 punch 20 die 30, 50 large basic circular cam element 32, 52 hub member 33, 53 web portion 34, 54 outer wall member 36 groove or ridge 38 reinforcing lip

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Giovanni See Albini 06795 Watertown Skillton Road, Connecticut, U.S.A. 100 (72) Inventor Robert E. Sconberg, 06022 Corinsville West Road, Connecticut, U.S.A., 26 (72) William A. Inventor Gordon 06022 Connectinsville Warner Road 35 Connecticut, Connecticut, USA

Claims (15)

[Claims] 1. A hollow, substantially cylindrical inner hub member having an inner, outer surface and first and second axial ends, radially spaced from said inner hub member;
An outer wall having an inner, outer surface and first and second axial ends; and extending between a first axial end of the outer wall and a second axial end of the hub member. An element for use in an assembled camshaft having a web portion joining the outer wall to the hub member. 2. The element of claim 1 wherein said outer wall is cylindrically shaped to provide a journal bearing surface. 3. The element of claim 1 wherein said outer wall is provided with lobes to provide a cam surface. 4. The element of claim 1, wherein the web portion forms a right angle with the outer wall and the hub member. 5. The element of claim 1 further comprising means for providing a torsional lock between said element and a camshaft tube to which said element is mounted during assembly of said camshaft. 6. The means for providing a torsional fixation between said element and said camshaft tube comprises one mechanical feature, said feature comprising a non-cylindrical inner surface of said hub member and said camshaft. 6. Matching the matching mechanical features on the shaft tube.
Element. 7. The element of claim 6, wherein the mechanical feature for making the interior surface of the hub member non-cylindrical comprises at least one axially oriented groove or ridge on the interior surface. 8. The means for effecting a torsional fixation between said element and a camshaft tube to which said element is mounted during assembly of said camshaft is provided by at least one of said hub member and said camshaft tube. The element of claim 5, comprising a swaged recess. 9. The means for providing a torsional lock between said element and a camshaft tube to which said element is mounted during assembly of said camshaft includes at least one at least one member between said hub member and said camshaft tube. The element of claim 5, comprising a weld. 10. The means for providing a torsional lock between said element and a camshaft tube to which said element is mounted during assembly of said camshaft includes at least one at least one member between said hub member and said camshaft tube. 6. The element of claim 5, comprising a brazed connection. 11. The hub member, the outer wall member and the web portion,
The element of claim 1 formed as one piece from sheet metal. 12. The element of claim 1 wherein the outer wall member and the web portion are formed as a single piece from sheet metal, and the hub member is formed from a tube and joined to the web portion. , 13. The element of claim 1, further comprising a reinforcing lip extending radially inward from at least a portion of a second axial end of an outer wall of the element. 14. A hollow, substantially cylindrical inner hub member having an inner, outer surface, and first and second axial ends, radially spaced from said inner hub member.
An outer wall having an inner, outer surface and first and second axial ends; and extending between a first axial end of the outer wall and a second axial end of the hub member. An element for use in an assembled camshaft having a web portion between the axial ends of the hub member and joining the outer wall to the hub member. 15. The element of claim 14, further comprising a reinforcing lip extending radially inward from at least a portion of a second axial end of an outer wall of the element.