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Publication numberUS3915129 A
Publication typeGrant
Publication dateOct 28, 1975
Filing dateSep 18, 1974
Priority dateSep 18, 1974
Publication numberUS 3915129 A, US 3915129A, US-A-3915129, US3915129 A, US3915129A
InventorsFulghum Leonard Owen, Rust Robert H
Original AssigneeFulghum Leonard Owen, Rust Robert H
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Internal combustion engine
US 3915129 A
Abstract
In an internal combustion engine of the type having a timing cam with a distance from center to cam surface with varies along its axis of rotation and at least one cam follower which rides on the cam surface to operate a valve so that the valve operating characteristics vary as a function of the position of the cam follower along the axis of rotation of the cam, the improvement wherein the cam follower includes a ball having a flat surface engaging the cam surface so that a line of contact always exists between the ball and the cam surface and means for mounting said ball in the follower, producing a mechanism which is durable, cheap to manufacture and adaptable to present day engines.
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Description  (OCR text may contain errors)

United States Patent 1191 Rust et a1. 5] Oct. 28, 1975 INTERNAL COMBUSTION ENGINE [76] Inventors: Robert H. Rust, 1073 Hampton Z"',"f g f 3 Road, Daytona Beach, Fla. 32014; & Leonard Owen Fulghum, 26 63rd Attorney, Agent, or Fzrm-Cus man, ar y St., Savannah, Ga. 31405 Cushman [22] Filed: Sept. 18, 1974 57 ABSTRACT [21] Appl. No.: 507,240 In an internal combustion engine of the type having a timing cam with a distance from center to cam surface with varies along its axis of rotation and at least one l23l90.lli%ll4/l5gz cam follower which rides on the cam surface to oper d 0 2 90/16 ate a valve so that the valve operating characteristics o 15 9O vary as a function of the position of the cam follower along the axis of rotation of the cam, the improvement 56 R f Ct d wherein the cam follower includes a ball having a flat 1 e erences l 6 surface engaging the cam surface so that a line of UNITED STATES PATENTS contact always exists between the ball and the cam 1,729,448 9/1929 Michell 74/569 surface and means for mounting said ball in the fol- 2,l5l,832 39 ug i---. 74/569 lower, producing a mechanism which is durable, 3,270,726 9/1966 Cott0n.... 74/569 heap to manufacture and adaptable to present day 3,523,465 8/1970 Harre11.... 123/9018 engines 3,730,150 5/1973 Codner l23/90.l8

1215,7515 2/1924 Michell 74/569 1 Claim, 2 Drawing Figures I zzairt'" US. Patent Oct. 28, 1975 3,915,129

, Z2 Ji 0%? J 1. z Z

INTERNAL COMBUSTION ENGINE BRIEF DESCRIPTION OF THE PRIOR ART AND SUMMARY OF THE INVENTION The invention relates to an improved internal combustion engine of the type having a timing cam and a cam follower which rides on the cam surface to operate a valve.

Heretofore, one of the major compromises affecting the performance of an automobile engine has been valve timing, duration and lift (generally referred to as TDL). Valve TDL determines to a large extend the smoothness and power characteristics of an engine at various RPMs. With conventional engines, due to valve TDL, an engine with a smooth idle is unfortunately limited in its power production at high RPM. Conversely, an engine that produces optimum power at high RPM lacks smoothness and tractability at lower speeds. The reason for this problem is that the breathing characteristics of the engine, i.e., the ability of the engine to draw in a full charge of air-gas mixture into the cylinder and, after combustion, to reject the spent exhaust gasses, changes with engine RPM. In conventional engines, however, the valve TDL is fixed while the breathing characteristics of the engine change with RPM. Accordingly, the valve TDL is conventionally a compromise to produce relatively smooth idle with adequate power at high RPMs. This compromise produces neither optimum smoothness at idle nor optimum power at high RPM. I

One possible technique to deal with this problem which has been suggested in the past is to construct the cam to have a distance from center to cam surface which varies along its axis of rotation. The cam follower can then be shifted along its axis of rotation as a function of engine speed by centrifugal or other mechanisms so that the cam follower rides on a portion of the cam surface which is optimum for the speed at which the engine is rotating. The US. Pat. No. 2,980,089, to Sampietro, is typical of this general type of improved engine.

The primary drawback to improvements of this type in the part is that they provide essentially a single point of contact between the cam follower and the cam surface. The most common mechanism in this type of structure employs a roller having a rounded contour which enables it to follow the varying contours of the cam surface.

However, this single point of contact is insufficient for the surfaces of the cam follower and the cam surface to endure the tremendous pressures which result from the inertia in the valve train mechanism. In contrast with those variable cam arrangements having a point of contact, a conventional lifter has a line of contact of about three-eighths inch with the conventional surface which permits it to stand up under longrange operating conditions.

The present invention relates to an improved internal combustion engine in which a cam follower is employed which includes a ball having a flat surface engaging the cam surface. This engagement results in a line of contact which always exists between the ball and the cam surface. The result is a mechanism which is simple, durable, cheap to manufacture and easily adaptable to present day internal combustion engines.

At least two patents in the prior art describes arrangements of this general type which do not have a single point of contact. The U.S. Pat. No. 3,618,573, to Allen, describes an arrangement in which a universally mounted rocker is used. Such a rocker, however, may not be entirely practical due to the necessity of the rocker mechanism being subjected to tremendous lateral acceleration because the entire rocker must follow the contours of the cam lobe. The US. Pat. No. 3,730,150, to Codner, describes a mechanism in which a roller is used and a line of contact is attempted to be maintained at a fixed angle. This fixed angle is not compatible with varying angles of the cam lobe.

Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. ll shows a cut-away view of a portion of an improved internal combustion engine of this invention;

FIG. 2 shows a schematic view of the cam follower and can which comprise the improvement of this invention.

DETAILED DESCRIPTION OF THE DRAWINGS Reference is now made to FIGS. 1 and 2 which illustrate the improvement of this invention. As in conventional internal combustion engines, cam 20 is mounted for rotation with the engine and the speed of rotation of the timing cam is a function of the speed of rotation of the engine. Further, cam 20 is mounted in any conventional way so as to be movable along its axis as a function of the engine RPM. Any conventional mechanism, such as the arrangement which is described in the Allen US. Pat. No. 3,618,573, can be employed. Centrifugal, hydraulic, electrical or any other mechanisms for moving the cam shaft can be employed and the way in which that shaft is moved along its axis is not part of the invention of this application.

Also, in the same fashion as in conventional engines, a mechanical cam follower or lifter 22 is mounted for longitudinal movement as it follows the surface of cam 20. It will, of course, be understood that while the embodiment of this application illustrates a mechanical lifter, hydraulic and other conventional lifters can also be employed in the same fashion.

However, in contrast with conventional arrangements, the cam follower 22 in the embodiment of this invention comprises a ball 24 having a flat surface 26 which engages the surface of cam 20. As can be seen in FIG. 2, cam 20 has a distance between its axis of rotation and its surface which varies along the length of that axis so that, as cam 20 is moved in the direction of the arrows of FIG. 2, the flat surface 26 engages different portions thereof to change the TDL characteristics of the valve which is mechanically or otherwise connected to the lifter 22. By using a ball having a flat surface, a continuous line of contact always exists between the ball and the cam surface and this results in a mechanism which is practical, durable, cheap to manufacture and adaptable to present day engines.

Many changes and modifications in the above described embodiment of the invention can, of course, be carried out without departing from the scope thereof. Accordingly, that scope is intended to be limited only by the scope of the appended claims.

What is claimed is:

1. In an internal combustion engine of the type having a timing cam with a distance from center to cam having a flat surface engaging the cam surface so that a line of contact always exists between the ball and the cam surface and means for mounting said ball in said follower.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1729448 *Dec 13, 1928Sep 24, 1929Michell Crankless Engines CorpCrankless engine
US2151832 *Sep 16, 1935Mar 28, 1939Ettore BugattiCam motion transmitting device
US3270726 *Oct 20, 1965Sep 6, 1966Gen Motors CorpValve tappet
US3523465 *Oct 31, 1968Aug 11, 1970Gen DeliveryAdjustable cam shafts
US3730150 *Oct 20, 1971May 1, 1973S CodnerMethod and apparatus for control of valve operation
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4800856 *Mar 11, 1985Jan 31, 1989Outboard Marine CorporationAbrasion resistant roller apparatus for internal combustion engines
US4850311 *Dec 9, 1988Jul 25, 1989General Motors CorporationThree dimensional cam cardanic follower valve lifter
US4936155 *Nov 25, 1988Jun 26, 1990Utah Transmission CorporationInfinite speed variation, constant power, ripple-free transmission
US5159906 *May 3, 1991Nov 3, 1992Ford Motor CompanyAdjustable valve system for an internal combustion engine
US5188067 *Jun 30, 1992Feb 23, 1993Ford Motor CompanyAdjustable valve system for an internal combustion engine
US5275116 *Apr 21, 1992Jan 4, 1994Merrow Machine Company, Inc.Cam and wobble follower looper drive for sewing machine
US5297446 *Feb 1, 1993Mar 29, 1994Therm-O-Disc, IncorporatedSwitch calibration mechanism
US5299516 *Jul 1, 1992Apr 5, 1994Suzuki Manufacturing Co., Ltd.Looper drive mechanism of a sewing machine
US5392664 *Aug 14, 1992Feb 28, 1995Gogins; Laird B.Continuously variable transmission
US5803033 *Dec 2, 1996Sep 8, 1998Toyota Jidosha Kabushiki KaishaValve drive apparatus for an internal combustion engine having a convex shim between a cam and a valve
US5832889 *May 12, 1997Nov 10, 1998Toyota Jidosha Kabushiki KaishaValve driving apparatus
USRE32802 *Jul 7, 1987Dec 20, 1988Cummins Engine Company, Inc.Two-cycle engine with improved scavenging
EP0777039A1 *Nov 28, 1996Jun 4, 1997Toyota Jidosha Kabushiki KaishaValve drive apparatus for an internal combustion engine having a convex shim between a cam and a valve
WO1996021090A1 *Dec 1, 1995Jul 11, 1996Stilian Tzonev GantschevRegulating hydraulic drive of valves for timing gear
WO2000042300A1 *Jan 12, 2000Jul 20, 2000Aztec IncImprovements in a variable valve timing system for an internal combustion engine
Classifications
U.S. Classification123/90.18, 74/569
International ClassificationF01L13/00
Cooperative ClassificationF01L13/0042
European ClassificationF01L13/00D6B