US 3292604 A
Description (OCR text may contain errors)
Dec. 20, 1966 w. J. RIFFE' ROCKER ARM OPERATING AND TIMING APPARATUS FOR INTERNAL COMBUSTION ENGINE Filed Oct. 20, 1964 2 Sheets-Sheet l INVENYZOR.
14 11/1512: JIflIf/k, BY
Dec. 20, 1966 w, RIFFE 3,22,504
ROCKER ARM OPERATING AND TIMING APPARATUS V FOR INTERNAL COMBUSTION ENGINE Filed 001:. 20, 1964 2 Sheets-Sheet 2 FIG: 42
IN VEN TOR.
William J/Fiffe, v
United States Patent s 292 604 ROCKER ARM oPERATING AND TIMING APPARATUS FOR INTERNAL COMBUS- TION ENGINE William Joseph Riffe, 217 Bickley Road, Glenside, Pa. 19038 Filed Oct. 20, 1964, Ser. No. 405,197 6 Claims. (Cl. 123-90) This invention relates to internal combustion engines and, more particularly, to a novel rocker arm operating apparatus which permits a change in timing of the operation of the intake and exhaust valves in relation to movement of the pistons while the engine is running.
In general, this invention teaches the replacement of the standard, generally vertically positioned push rods by carn equipped rotating shafts, said shafts having means rocker arms.
Overhead Camshafts, when used to operate the intake and exhaust valves, are driven by gearing or chains from the crankshaft located externally to the block. The required series of separate, multiple gears or chains are heavy and require that the engine be enlarged to accommodate this mechanism which, in the push rod system, is substantially mounted within the block. Also, slippage and play of the driving gears and chains reduces the overall efficiency of the engine.
In the push rod-rocker arm system, high speed operation with high efliciency is prevented by physical distortion of the push rods and their tendency to float in relation to their operating cams. This causes the rocker arms and valves to open or close at the wrong time.
Therefore, it is the primary object of this invention to avoid the inefiiciencies and limitations of both the overhead camshaft system and rocker arm-push rod system of valve operation identified above by substituting substantially, a rotating cam equipped shaft in place of each push rod in the engine block.
It is a further object of this invention to provide in an apparatus satisfying the above objects means for mechanically or hydraulically adjusting the timing of the rocker arm operation in relation to the speed of the engine while the engine is running.
Further objects of this invention are the provision of apparatus meeting the above objects and, in addition, providing means for quick and easy replacement of the rocker arm cam when a different lift or dwell characteristic is desired Without substantial disassembly of the engine. The apparatus of this invention makes possible a wide choice of cam profiles and eliminates thrust or side play on the valve assembly associated with a sharp profile cam. The apparatus of this invention is advantageously stiff with no whip or hysterisis of shaft and valve lash is minimal because shaft expansion can be absorbed by supporting bearing members. With elimination of pushrods and lifter-tappet assemblies, the reciprocating mass is small enough so that high speeds are possible without appreciable valve float.
These objects and other attendant advantages of this invention will become more apparent from the description set forth hereinbelow and from the drawings attached hereto wherein FIGURE 1 is a schematic view in side elevation of a 3,292,604 Patented Dec. 20, 1966 preferred form of rocker arm actuating shaft and its drive system shown in relation to the engine block;
FIGURE 2 is a partial schematic perspective view of one form of the rocker arm operating cam and shaft;
FIGURE 3 is a partial schematic perspective view of a modified form of the rocker arm operating cam and shaft as shown in FIGURE 2;
FIGURE 4 is a view in side elevation and partly in section showing the preferred form of the mechanical adjustable rocker arm actuating apparatus of this invention; and
FIGURE 5 is a view in side elevation and partly in section illustrating one form of the hydraulically adjustable rocker arm operating apparatus of this invention.
This invention in part may generally be described as the substitution of a plurality of cam equippedrotating shafts in place of the reciprocating push rods so that the rocker arms continue their standard operation of controlling the spring biased valves by reciprocating while moving across the rotating inclined cam surfaces. The cam equipped, rotating shafts are further provided with means for independently rotating the cam forward or behind the driving shaft thereby changing the valve actuating position or timing in relation to the position of a particular piston in the engine.
The following description is directed to the specific forms of the invention illustrated in the drawings and is not intended to limit the scope of the invention itself which may be practiced in a wide variety of forms and arrangements.
Referring preliminarily to FIGURE 1 of the drawings, a standard engine block is indicated by the dot and dash lines and identified by the numeral 10. A geared shaft 12, which drives a series of cam equipped shafts 20, is supported along its length by a plurality of bearings 14 and is located within the engine block in the recess which presently contains the conventional push rod camshaft. Typically, the geared shaft 12 is provided with a series of preferably helical gears 15a one of which is shown in FIGURE 1, and at the forward end extends through the front of the engine block 10 where a spur gear 16 is mounted. Spur gear 16 meshes with drive gear 17 which may be mounted on the crankshaft (not shown) or may be an idler gear between said crankshaft gear and gear 16. Geared shaft 12 is mounted substantially parallel to the crankshaft or parallel to the longitudinal axis of the engine and earn shafts 20, one of which is shown in FIGURE 1, are mounted generally vertically or forming a V in relation to shaft 12 as seen from the front. As a result of the meshing of gears 17 and 16, geared shaft 12 rotates in a predetermined timed relationship with the crankshaft.
A rocker arm operating shaft 20 is mounted Within the block at every point where a push rod is located in the standard push rod engine so as to operate at least one rocker arm in the engine head and thereby control the operation of at least one valve. Shaft 20 is provide-d with a plurality of bearings 22 distributed along its length to hold the shaft rigid in relation to the block 10 and geared shaft 12. Helix gear 15 preferably is attached to the lower end of shaft 20 so as to mesh with a similar gear 15a on shaft 12 whereby shaft 20 is caused to rotate in timed relation to shaft 12. Shaft 20 is positioned in a plane perpendicular to that of shaft 12.
The upward end of shaft 20 extends out of the engine block and is equipped with a disc shaped cam 24 which has an inclined surface 26 upon which presses the tip 29 of a standard rocker arm 28. The rocker arm is mounted on the engine block 10 in the standard way so that it pivots on a center fulcrum base and presses down at one end not shown, against a valve stem (either intake or exhaust) opening the valve against a spring mounted on the valve stem and engine block. The rocker arm reciprocates as indicated by the arrows when tip 29 is raised. The valve engaging end (not shown) displaces a valve 'downward and open when tip 29 is raised. 'When cam 24 rotates so that the surface 26 presents the lower end 260:, then rocker arm tip 29 moves downward allowing 'the rocker arm to reciprocate and control movement of the valve or valves. It is possible to mount more than one rocker arm on a single cam 24 or mount a plurality of cams on a single shaft 20.
A modified form of the rocker arm cam 24 shown in FIGURES 1 and 2 is the assembly shown in FIGURE 3. In this form, cylinder cam 30 is fixedly mounted on shaft 20 and is provided with an axial bore 32 in which a stem 34 is mounted for vertical movement. A roller 36 is attached to stem 34 by pin 37 and moves along the inclined surface 31 of cam 30 under pressure of rocke-r arm tip 29. A spring 35 is provided to dampen any movement of stem 34 in the axial direction. rotates, roller 37 rides along the inclined surface 31 cansing stud 34 and rocker arm end 29 to reciprocate. The prime advantage of the assembly of FIG. 3 is that the roller dispenses with the small amount of friction existing in the design shown in FIG. 2.
This invention further includes means for adjusting the position or timing of the rocker arm operating cam in relation to the location or movement of the piston in the related cylinder. It is well known that at higher vr.p.m. or engine speed the timing of the opening and closing of the intake and exhaust valves will, for greater efficiency, be dilTere-nt from the settings for normal speeds. The apparatus disclosed herein provides automatic means for mechanically or hydraulically causing the cam to assume a new position relative to the rocker arm while the engine is running thereby adjusting the engine for greater efliciency at each range of speed.
The preferred form of the mechanically adjustable rocker arm actuating assembly is shown in FIG. 4. In this form, geared shaft 40, serving the same function as shaft 12 in the FIG. 1 embodiment, is equipped with helix gear 42 which meshes with helix gear 44 formed on the surface of a tubular shaft 46. In place of the solid shaft 20 of the FIG. 1 embodiment, shaft 46 has an axial bore 48 extending the full length of the shaft.
Mounted for limiited axial movement with shaft 46 is a piston 50 having at the lower end, as shown in FIG. 4, a round cam 54 and a flange 52 by which a spiral spring 56 is held captive against theannular base 47 of outer shaft 46. At the upward end, piston 50 has an axial bore 58 in which is mounted cam stem 60 sup- As cam 30 porting cam 62. A screw 63 extends-through cam 62 and cam portion 62a and is threaded into stem 60. The stem 60 is splined at 60a to provide ready replacement of cam 62 for another cam having a different profile. A knurled knob 64 is aflixed to screw 62. A retaining stud 46a; fixed in shaft 46 and engaged in slot 60b at stem 60, prevents axial movement of cam stem 60 but allows the stem and cam 62 to rotate or revolve relative to shaft 46.
An axially directed, outer shaft slot 49 is formed in the wall of shaft 46 to receive a protruding piston aligning key 51 attached to piston 50 whereby piston 50 is caused to rotate with shaft 46 but is freeto move axially in response to a force exerted on round cam 45.
An inclined piston adjusting slot 55 is formed in the wall of piston 50 adjacent the bore 58 and a cam roller or wedge 60c, attached to cam stem 60, is positioned within slot 55. Upon movement of piston 50 in the axial or upward direction, the walls defining inclined slot 55 move so as to cause the roller 60c held captive therein to move to the left as shown in FIG. 4. As a result, cam stem 60 and cam 62 are rotated in a clockwise direction as seen from the top of the form shown in FIG. 4. Such movement, distinct and separate from the rotation of shaft 46, would cause rocker arm tip 70 to descend as the cam 62 moved to present its lower surface. Similarly, when piston 50 is caused to descend relative to shaft 46, slot 55 causes roller 600 to move to the right as shown in FIGURE 4 thereby causing the cam 62 to rotate counter-clockwise.
A cam adjusting rod 72 is shown at thebottom of FIG.
4 and consists of rod 73 mounted parallel to geared shaft 40 and having an enlarged cam collar 74 positioned thereon. When the rod 72 is moved to the left as shown in FIG. 4, piston 50 is caused to move upward against spring 56 thereby causing cam 62 to rotate clockwise as viewed from the top. When rod 72 is moved to the right, piston 50 descends by virtue of spring 56 causing the stem 60 and cam 62 to rotate counter-clockwise as viewed from above. Movement of cam adjusting rod 72 may be controlled by the operator from within the vehicle or may. be operatively set within the engine compartment while Shaft is provided with an axial bore 84 which extends a portion of the length of the shaft from the top.
Mounted within bore 84 for axial movement relative thereto is piston 86 which is equipped with a protruding alignment stud 87 mounted within axially directedslot 88 formed in the wall of shaft 80. Stud 87 and slot 88 cause piston 86 to rotate with shaft 80 but allow limited axial movement relative thereto. A stem 90 is mounted for limited rotary movement within a bore 86a in piston 86 and supports at its upper end cam 92 held thereon by threaded screw 94. A rocker arm tip 105 presses on cam 92. A retaining stud 80a locks the stem 90 to shaft 80 preventing axial movement of the stem relative to the shaft but allowing limited rotation thereof. A spring 96 is compressed between piston 86 a and the enlarged portion 90a of the stem 90. A protruding roller 90c attached to stem 90 is positioned within inclined slot 99 formed in the wall of piston 86 causing the stem 90 and cam 92 to rotate when piston 86 moves in a vertical direction.
An oil chamber 100 is formed within shaft 80 beneath piston assembly 86 and oil ports 102 formed in shaft 80 allow engine oil flowing through cam oil gallery 104 to pass into chamber 100 and hydraulically affect the position of piston 86 against spring 96 within bore 84.
In operation, this form of the apparatus of this invention functions substantially as follows. When the speed or r.p.m. of the engine builds up, oil pressure is increased by the standard oil pump and that pressure is reflected in the pressure of the oil in oil gallery 104 and in chamber 100. The increased oil pressure presses against the bottom of piston 86 causing it to rise thereby causing the inclined walls of slot 99 to displace the roller 90c to the left as-showniin FIG. 5 and rotating the cam clockwise as seen from thetop. Similarly, upon a decrease in oil pressure acting upon piston 86 in oil chamber 100, spring 96 forces piston 86 downwards,
rotating cam 92 in the counter-clockwise direction. The
movement of piston assembly 86 axially may be set by In this form, shaft 80 is r substituting a spring 96 of varying compression strengths.
Pressure in oil gallery 104 and in chamber 100 may be controlled by a check valve (not shown) preferably located at the exit end of the gallery.
Of course, like the mechanical adjusting assembly shown in FIG. 4, adjustment of the rocker arm cams can occur while shaft 46 of the FIG. 4 embodiment and shaft 80 of the FIG. 5 embodiment are rotating and causing the rocker arms to reciprocate. It is one of the unique advantages of this invention that adjustment to the most efficient valve setting or opening time may be continually made for the particular engine speed then employed.
It should also be understood that the basic cam shaft of this invention can be positioned so that the cam works directly upon the valve stem thereby eliminating the necessity for a rocker arm. All other apparatus of this invention would function in the same manner as if a rocker arm were present.
It is another advantage of this invention that the proposed apparatus can be utilized in the existing engine block design with only minor changes necessary to the head and block assemblies. The cost of manufacture of the geared drive shaft and the geared cam shaft assemblies will be competitive to the cost of the presently used camshafts and lift rods.
Although this invention has been described with reference to specific forms and embodiments thereof, it will be apparent to those skilled in the art that various changes other than those referred to above may be made in the form of the apparatus, that equivalent elements may be substituted for those illustrated in the drawings, that parts may be reversed, and that certain features of the invention may be used to advantage independently of the use of other features, all within the spirit and scope of the invention as defined in the appended claims.
Having thus described my invention, I claim:
1. In an internal combustion engine having a crankshaft and a cylinder valve controlled by a rocker arm, rocker arm operating apparatus comprising a first shaft mounted for rotation having a cam surface positioned proximate one end and extending about the axis of said shaft, said cam surface extending generally along a plane disposed at an acute angle relative to the axis of said shaft, said shaft having external gear means positioned proximate the opposite end thereof,
a member extending upwardly through the center of said cam surface and mounted for shifting movement vertically relative to said cam surface, said member being urged downwardly by said rocker arm, roller means on said member in rolling contact with the cam surface whereby said roller means moves over the surface of the cam as said first shaft rotates, causing the rocker to reciprocate in a vertical direction, and
a geared shaft mounted for rotation and positioned substantially perpendicular to the first shaft proximate the gear means, said geared shaft being driven in timed relation to the crankshaft and having gears to engage the gears on the first shaft whereby the cam surface is caused to rotate in timed relation to the crankshaft thereby imparting a reciprocating motion to the rocker arm.
2. In a standard internal combustion engine having a piston, cylinder, crankshaft, cylinder valve and valve operating rocker arm, apparatus for operating and varying the timing of the rocker arm in relation to piston movement comprising a first shaft mounted for rotation having an internal axial bore and means mounted thereon for causing shaft to rotate in timed relation to the reciprocatory movement of a piston,
a second shaft mounted within the bore of said first shaft and attached thereto so that the second shaft rotates with the first shaft and can move axially independent of the first shaft,
a cam member attached to both shafts by means whereby the cam member rotates with the first shaft and revolves as the second shaft moves axially in relation to the first shaft, said cam member having a cam surface formed within a plane extending transverse to the axis of the second shaft and in contact with the rocker arm so that upon rotation of the cam the rocker arm reciprocates in a vertical direction, and
means for causing said second shaft to move in an axial direction while said first shaft rotates whereby the relative position of the cam surface in contact with the rocker arm can be varied in relation to the relative position of the piston.
3. The apparatus as defined in claim 2 wherein means causing axial movement of the second shaft comprises a rod mounted substantially perpendicular to the second shaft, said rod having a cam surface thereon in contact with the distal end of said shaft,
a spring mounted on said shaft urging said shaft into contact with said cam surface whereby movement of the rod in one direction causes the cam surface to push the shaft axially in one direction and movement of the rod in the opposite direction causes the spring to push the shaft in the opposite direction.
4. The apparatus as defined in claim 2 wherein means causing the axial movement of the second shaft comprises a source of oil under pressure, said pressure increasing as the piston reciprocates at a higher speed,
means directing the fluid to a position within the bore of the first shaft and against the second shaft so as to cause the second shaft to move axially from an initial position as the pressure increases thereby causing the cam surface to revolve in one direction, and
spring means for returning the second shaft to the initial position and thereby causing the cam surface to revolve in the opposite direction upon the decrease in oil pressure.
5. The apparatus as defined in claim 2 further includa geared shaft mounted substantially perpendicular to the first shaft and having gear means for rotating the first shaft, said geared shaft connected to the crankshaft for rotation therewith in timed relation.
6. In a standard internal combustion engine, a hydraulic adjustable rocker arm operating apparatus comprising a generally vertically positioned tubular shaft mounted for rotation, said shaft being rotated in timed relation to the crankshaft in general and the adjacent piston in particular,
a piston assembly mounted within the shaft, said assembly having a stud extending into an elongated axial slot in the tubular wall of the shaft thereby causing the piston assembly to rotate with the shaft but allowing axial movement of the assembly relative to the shaft,
a cam stem mounted within a bore extending inwardly from the upward end of the piston assembly, said ca m stem having a roller stud extending into an elongated slot in the piston assembly and positioned obliquely to the axis of the piston assembly thereby causing the cam stem to rotate with the piston assembly and allowing the stem to revolve relative to the piston assembly as the assembly moves axially, said cam stem having locking means preventing axial movement of the cam stem relative to the shaft,
7 S a cam surface mounted on the cam stem, said surface References Cited by the Examiner forming generally a plane transverse to the axis UNITED STATES PATENTS of the cam stern and providing a surface upon which the rocker arm presses so that upon rotation of the earn, the rocker arm is caused to reciprocate 5 1,029,764 6/1912 Opsahl. 1,147,313 7/1915 Desort.
in a vertical direction, 11632223 6/1927 a spring pressing the piston assembly downwardly i 2,225,102 12/1940 Daub -90 the shaft, and 2, 0 ,787 12/1942 Kales 12390 means for directing engine oil under pressure into a 3 60 6/1954 Lantz 123-90 compartment in the shaft beneath the piston assem- 10 FOREIGN PATENTS bly whereby upon higher engine speed the increase in oil pressure causes the piston assembly to rise in the shaft therehy revolving the cam surface and MARK NEWMAN, Primary Examinen changing the position of the rocker arm relative the position of the adjacent piston in its cycle at 15 AL LAWRENCE SMITH, Examiner. any one instant of time.
229,033 2/ 1925 Great Britain.