US2804864A - Variable valve timing control - Google Patents

Description

Sept. 3, 1957 H. A. R OAN VARIABLE VALVE TIMING CONTROL 5 Sheets-Sheet 1 Filed Aug. 26, 1954 INVENTOR. A 30% ATTORNEY-5 Sept. 3, 1957 H. A. ROAN VARIABLE VALVE TIMING CONTROL 3 Sheets-Sheet 2 4 Filed Aug. 26, 1954 32m :65 Amman $2 304 wSwFCu 23E .mfinukxu J 2 v H H N m QM\ V, Q\\ 1 N 0 m m a \Q\ A W J g I S N W Sept. 3, 1957 H ROAN 2,804,864

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AT70F/VEYS' VARIABLE VALVE TIMING CONTROL Henry A. Roan, Minneapolis, Minn.

Application August 26, 1954, Serial No. 452,335

Claims. (Cl. 123-90) My invention relates to hydraulic valves in an internal combustion engine. in particular it relates to hydraulic valves of internal combustion engines having variable valve timing control.

The valve timing for operation of an internal combustion engine at high engine speed is not the best timing for starting, idling or very slow speed operation. It is desirable, therefore, to be able to easily and effectively alter the normal valve timing to a timing more suitable for starting and a slow speed operation.

My invention provides for improved and novel means for valve timing control which is independent of the valve train and independent of the source of fluid pressure. The former permits easy accessibility for servicing and provides a control which does not move with the valve lifter. The latter provides a full lubrication of the valve lifters at all ranges of operation. Further, my invention provides for a valve timing control which is variable between a amount of valve lift loss and zero lift loss and clearance. This variation permits a range of valve timing that will be more efficient for all engine speeds from starting to normal high speed operation.

It is an object of my invention to provide a novel and improved valve timing control for hydraulic valves which is more simple, less expensive, and more effective than any previously known in the art.

It is another object of my invention to provide a novel and improved valve timing control for hydraulic valves which is independent of the valve train and which provides for variable valve timing to give a predetermined range of valve timing variation.

it is another object of my invention to provide a novel and improved valve timing control for hydraulic valves which provides a full lubrication of the valve lifter at all ranges of operation and insures a fluid cushion between the movable parts of each valve lifter at all times; this eliminates noise expected to accompany valve lift loss or valve lifter clearance.

it is another object of my invention to provide a novel and improved valve timing control for hydraulic valves which consists of an automatically controlled check valve positioned outside of the hydraulic valve train; the control of said check valve providing positive and accurate adjustment of the hydraulic valve lifters from zero clearance to a maximum clearance which produces a range of valve timing variations that will be efiicient at all speeds.

it is a further object of my invention to provide a novel and improved valve timing control which can be used to control a plurality of hydraulic valves which consists of an automatically controlled check valve positioned outside of the valve train of each hydraulic valve; the con trol for said check valve comprising an unseating post actuated by a governor motivated by the engine and which can be adjusted to produce a range of valve timing variations that will be eflicient at all speeds.

These and other objects will be disclosed in the course of the following specification and claims, reference being had to the accompanying drawings wherein:

States Patent ice Fig. 1 is a fragmentary view in top plan of an internal combustion engine provided with my invention;

Fig. 2 is a view in side elevation with some parts broken away of the structure shown in Fig. 1;

Fig. 3 is an enlarged view in section of a portion of the internal combustion engine of Fig. 2 showing my invention associated with one valve of one of the engines cylinders;

Fig. 4 is an enlarged view in section of a portion of the structure shown in Fig. 3 showing the detail of the valve lifter construction and the detail of the control unit of my invention associated therewith;

Fig. 5 is a fragmentary view in cross section of a combined check valve and pressure control valve installed between the oil pump and the control units of my invention;

Fig. 6 is a view partly in section and partly in top plan taken along the line 6-6 of Fig. 4;

Fig. 7 is a fragmentary view in side elevation taken along the line 77 of Fig. 4;

Fig. 8 is a fragmentary view in top plan showing the governor-operated control of my invention and two positions thereof;

Fig. 9 is a graphic illustration showing the valve timing when the parts are as shown in dotted lines in Fig. 8, which is at high speed operation;

Fig. 10 is a graphic illustration showing the valve timing when the parts are as shown in full lines in Fig. 8, which is at starting operation; and

Fig. 11 is a greatly enlarged fragmentary view in cross section showing a detailed portion of the valve lifter of Fig. 4.

Referring more particularly to the drawings, general reference numeral 11 indicates an internal combustion engine having a plurality of cylinders 12 and operative therein pistons 14. Each cylinder 12 is provided with an intake and exhaust valve 16. Although only one valve 16 has been shown in the drawings, both the exhaust and intake valves are similar in construction. The valve is biased in a closed position by means of a spring 18. General reference numeral 20 indicates a valve operating mechanism comprised of 'a motor-driven cam 22, and a valve lifter 24 connected to a push rod 26 which actuates lever 28 to open valve 16.

Referring more particularly to Fig. 4, the construction of valve lifter 24 is shown in detail. A tappet 30 provided with a bore 32 is open at its upper end 34 and closed at its lower end 36. Press fit within the upper part of bore 32 is a cylinder 38 provided with a central bore 40 and a reduced bore 42 at its lower end 44. An inner surface of lower end 44 defines a piston seat 45 limiting the collapsing movements of plunger 46 mounted within cylinder 33 for longitudinally extending and retracting movement.

Plunger 46 at its lower end 48 has an annular cavity 49 defining a cylindrical inner edge 50. Surrounding bore 42 and extending outwardly from piston seat 45 is an annular projection 52. Referring in particular to Fig. 11, it is shown that during retracting movements of plunger 46 annular projection 52 cooperates with inner edge to trap a cushion of fluid between piston seat 45 and plunger 46. This structure insures a fluid cushion between the movable parts of the valve lifter 24 at all times which acts to eliminate noise expected to accompany valve lift loss or valve lifter clearance.

Push rod 26 is secured to the upper end 54 of plunger 46. Defined within the lower portion of bore 32 of tappet 30 is a fluid reservoir 56. Plunger 46 is biased outwardly from cylinder 38 by means of a spring 58.

Operating fluid for the hydraulic valve lifter 24 is the pressure-fed oil from the lubricating system of the engine 11 and is supplied through conduit 60, see Fig; 5, from an oil pump not shown in the drawings. Conduit leads througha. check valvefil, which. acts. to. prevent oil from draining back into the crankcase .when the oil pump is not operating, into chamber- 62 defined by member 63. Valve 61 acts to eliminate noisy, tappets in amoton that has been standing for any. length. of time. A pressure control 64 positioned, in member 6335 consists of a check valve 66 biased in its-closed position by. spring'68. Conduit 70-leads from check valve 66 back to the crankcase not shown in thedr-awings. Spring. 68is set sothat the oil, pump pressure is cut down to about. twenty pounds for delivery from chamber 62 to the valve: lifters 24. The fluid. pressure thus delivered. being-less than required to open valve 16 against the bias. of spring 18. Main pump line. 72- leads; from chamber 62' to branch conduits 74 which lead to the control units. designated by general reference numeral 76;

As. illustrated in this disclosure, my novel control unit 76 is used to controlithe valve timing for both the exhaust valve and the intake valve of a cylinder 12; however, it may be desirable in some instances to use a control unit 76 for each valve of the cylinder. Referring in particular to Fig. 6, the present embodiment of my invention shows that each control unit 76 is connected by means of conduit 78 to a juncture 80 of conduits 82 and 24. Conduit 82 leads to the oil reservoir 56 of the intake tappet and conduit 84 leads to oil reservoir 56 of the exhaust tappet.

Referring again to Fig. 4, control unit 76 is shown in detail. Branch conduit 74 leads through a check valve 86 positioned in a chamber 88 defined by member 90.

The open upper end 92 of member is closed by a plug 94 which carries a ball stop 96. The lower end 98 of member 90 is cylindrically shaped and provided with a bore 100, and positioned therein is an unseating post 102. Upper end 104 of unseating post 102 is adapted to contact check valve 86 to permit a controlled two-way flow through the valve. Unseating post 102 at its lower end 106 is connected to a sleeve 108. Lower end 98 of member 90 is provided with a small projection 110 which projects through the inclined slot 112 formed in the sleeve 108 as shown in Fig. 7, whereby rotation of sleeve 108 effects reciprocatory longitudinal movement of the sleeve on the lower end 98 of member 90 to control the movement of the unseating post 102. Each of the sleeves 108 is provided with a laterally projecting arm 114' connected to control linkage 116.

Control linkage 116 is connected to the arms 114 of each control unit, Fig. 1, and at its end 118 is connected to end 119 of an operating lever; 120 which is pivotally movable about point 121 between two positions by a governor indicated by general reference numeral 122, Fig. 8. Governor 122 consists of a frame 124 secured by screws 126 to a projection 128 of the engine block. Frame 124 supports bearings 130 and journalled therein is shaft 132. Secured to shaft 132 is a pulley 134 carrying lugs 136 to which are pivotally connected the weights 138 having weighted ends 139. Ends 140 of weights 138 are formed to engage in a groove 142 formed by annular members 144 of a sleeve member 146. A similar groove 148 is formed by annular members 150. Lever 120 has its opposite end 151 formed to engage in the groove 148. Governor 122 is motivated by a continuous V-belt 152 encircling a pulley 153 secured to the fan 154 and pulley 134. Fan 154 is operated by the conventional connection to the crankshaft, not shown in the drawings. Connected to lever 120 and frame 124 is .a spring 156; the bias of which is controlled by adjusting screw 158.

Theoperation of my-invention is as follows.

When the engine 11 is first started, sleeve 146 of governor 122 and lever 120' are biased by spring 156 in the position shown in full lines in Fig. 8; this positions linkage 116 and arms 114 so that each sleeve 108 is at the extremity of its movement in a longitudinally upwardly direction, At this position of sleeve 108; unseating post 102' holds check valve 86 at its maximum open position which allows a complete collapse of plunger 46, although there is al- 4 ways maintainedv a cushion of fluid between the plunger 46 and the piston seat 45. This maximum retracted position of plunger 46 effects maximum clearance in the valve train and a resultant lift loss which determines the valve timing shown in Fig. 10, which is favorable for starting operation.

As the speed of engine 11T increases, the rotation of weights 138 of the governor 122moves the weighted ends 139 outwardly; and correspondingly, ends 140 move sleeve 146 longitudinally along shaft 132, against the bias of spring 156. The extent of longitudinal movement is in direct relation to the engine speed, and this relationship is adjustable by means of screw 158. The movement of sleeve 146 effects a corresponding movement in the opposite direction of linkage 116 which acts to rotate sleeve 108 to move unseating post 102 in a downwardly direction. The downward movement of post 102 effects a closing of check valve 86 from its: maximum open position. which acts to correspondingly decrease-the clearance in the valve train and to decrease the lift loss. When sleeve 146 and lever 120 reach the position shown in dotted lines in Fig. 8, linkage 116 and arms114 position each sleeve 108 at the extremity of its movement in a longitudinally down- Wardly direction. At this point, end 104 of post 102 is out of contact with check valve 86; and this is the valves normal closed position. This normal position of check valve 86 effects zero clearance in the valve train and zero lift loss which determines the valve timing shown in Fig. 9, which is favorable for high-speed operation.

The movement of sleeve 146 between the two positions shown in Fig. 8 by the operation of governor 122 effects a positive control of unseating post 102 between its normal closed position at high-speed operation and its maximum open position at starting operation to effect a variable valve timing, between the values determined in Figs. 9 and 10, which is in direct relation to engine speed. This control gives a predetermined range of valve timing operations that-will be eflicient at all speeds of the engine.

It will be obvious to those skilled in the art that my invention may be modified by many substitutions and equivalents and that this disclosure is intended to be illustrative only. Therefore, I intend to be limited solely by the scope of the appended claims.

What I claim is:

1. In an internal combustion engine having a valve; valve operating mechanism comprising an engine-driven cam, yielding means biasing the valve toward closed position, and a valve-operating train between the cam and valve; said valve train comprising a longitudinally extendible and contractible valve lifter, said extendible and contractible valve lifter comprising a cylinder mounted for axial reciprocatory movement and a plunger mounted therein for longitudinally extending and retracting movements, said cylinder defining an expansion chamber and a piston seat limiting collapsing movements of the piston, a source of fluid under pressure, conduit means between the fluid pressure source and the expansion chamber of the valve litter, the fluid pressure thus delivered to the expansion chamber of the valve lifter being less than required to open the valve against said valve biasing means, and valve means associated with said conduit remote from the valve train for establishing either one-way flow through the conduit in the direction of the valve lifter to provide maximum valve lift and valve open periods of maximum duration or two-way flow through the conduit allowing collapsing of the valve lifter to provide a predetermined valve lift loss and correspondingly shortened valve open periods.

2. In an internal combustion engine having a valve; valve operating mechanism comprising an engine-driven cam, yielding means biasing the valve toward closed position, and a valve-operating; train between the cam and valve; said valve train comprising a longitudinally extendible and contractible valve liften saidextendible and contractible valve lifter comprising a cylinder mounted for axial reciprocatory movement and a plunger mounted therein for longitudinally extending and retracting movements, said cylinder defining an expansion chamber and a piston seat limiting collapsing movements of the piston, a source of fluid under pressure, conduit means between the fluid pressure source and the expansion chamber of the valve lifter, the fluid pressure thus delivered to the expansion chamber of the valve lifter being less than required to open the valve against said valve biasing means, a check valve interposed in said conduit and allowing flow therethrough only in the direction of the valve lifter, said check valve being located remote from the valve train, and means for selectively rendering said check valve ineffective and thereby allowing two-way flow through said conduit, the fluid pressure under control of the check valve normally maintaining zero clearance in the valve train and establishing a predetermined normal valve timing, whereby when the check valve is rendered ineffective by said last-named means it permits the collapse of said piston to provide a predetermined valve lift loss resulting in a different valve timing more favorable to starting and slow-speed operation.

3. The structure defined in claim 2, wherein said lastnamed means is variable between two positions to effect a valve lift loss variable between zero clearance and a maximum clearance determined by the maximum retracted position of the plunger established by said piston seat.

4. The structure defined in claim 3, wherein said lastnamed means comprises an unseating post movable between two positions and adapted to contact said check valve to variably control the position of said valve with respect to its seat, and control means for controlling the movement of said post.

5. The structure defined in claim 4, wherein said control means is mechanical and dependent upon the engine speed and adapted to control the extent of opening of said check valve in inverse proportion to engine speed.

6. The structure defined in claim 4, wherein said control means comprises, a member movable between two positions secured to said unseating post, a lever connected to said member, and a governor motivated by the engine being connected to and adapted to actuate said lever.

7. In an internal combustion engine having a plurality of valves; each valve having operating mechanism comprising an engine-driven cam, yielding means biasing the valve toward a closed position and a valve-operating train between the cam and the valve; each valve train comprising a longitudinally extendible and contractible valve lifter, each extendible and contractible valve lifter comprising a cylinder mounted for axial reciprocatory movement and a plunger mounted therein for longitudinally extending and retracting movements, each cylinder defining an expansion chamber and a piston seat limiting collapsing movements of the piston, a source of fluid under pressure, a conduit from said fluid source to a juncture, conduit means between said juncture and the expansion chamber of each valve lifter, the fluid pressure thus delivered to said expansion chambers being less than required to open said valves against said valve biasing means, and valve means remote from the valve trains and associated with said conduits between said fluid source and said juncture for establishing either one-way flow to the conduit in the direction of said valve lifter to provide maximum valve lift and valve open periods of maximum duration or a variable two-way flow through said conduit allowing variable collapsing of the valve lifter to provide a range of predetermined valve lift losses and correspondingly shortened valve open periods.

8. The structure defined in claim 7 and in combination therewith, a second valve means associated with said conduit between said fluid source and said first-named valve means for reducing the pressure of said source and preventing fluid from draining from said valve lifter back to said source should the pressure of said source cease to exist.

9. In an internal combustion engine having a valve; valve operating mechanism comprising an engine-driven cam, yielding means biasing the valve toward a closed position, and a valve-operating train between the cam and the valve; said valve train comprising a longitudinally extendible and contractible valve lifter, said extendible and contractible valve lifter comprising a cylinder mounted for axial reciprocating movement and a plunger mounted therein for longitudinally extending and retracting movements, said cylinder defining an expansion chamber and a piston seat limiting collapsing movements of the piston, the lower end of said plunger having an annular cavity defining a cylindrical inner edge, and an annular projection extending outwardly from said piston seat in coaxial relationship with said cylindrical inner edge, said annular projection and cylindrical inner edge cooperating to trap a cushion of operating fluid between said plunger and said piston seat at the maximum retracted position of said plunger which insures a fluid cushion between the movable parts of said valve train at all times.

10. In an internal combustion engine having a valve; valve operating mechanism comprising an engine-driven cam, yielding means biasing the valve toward closed position, and a valve-operating train between the cam and valve; said valve train comprising a longitudinally extendible and contractible valve lifter, said extendible and contractible valve lifter comprising a cylinder mounted for axial reciprocatory movement and a plunger mounted therein for longitudinally extending and retracting movements, said cylinder defining an expansion chamber and a piston seat limiting collapsing movements of the piston, the lower end of said plunger having an annular cavity defining a cylindrical inner edge, an annular projection extending outwardly from said piston seat in coaxial relationship with said cylindrical inner edge, said annular projection and cylindrical inner edge cooperating to trap a cushion of operating fluid between said plunger and said piston seat at the maximum retracted position of said plunger, a source of fluid under pressure, conduit means between the fluid pressure source and the expansion chamber of the valve lifter, the fluid pressure thus delivered to the expansion chamber of the valve lifter being less than required to open the valve against said valve biasing means, and valve means associated with said conduit remote from the valve train for establishing either oneway flow through the conduit in the direction of the valve lifter to provide maximum valve lift and valve open periods of maximum duration or two-way flow through the conduit allowing collapsing of the valve lifter to provide a predetermined valve lift loss and correspondingly shortened valve open periods.

References Cited in the file of this patent UNITED STATES PATENTS 1,542,839 Reeves June 23, 1925 2,019,252 Cottingharn Oct. 29, 1935 2,339,238 Buckley Jan. 18, 1944 FOREIGN PATENTS 564,507 Great Britain Oct. 2, 1944

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