US1679794A - Valve gear - Google Patents

Description

Aug. 7, 1928. 1,679,794

w. F. SMITH VALVE GEAR Filed Nov. 9, 1925 2 Sheets-Sheet .1

Aug. 7, 1928.

W. F. SMITH VALVE GEAR Fild Nov. 9, 1925 2 Sheets-Sheet 2 Patented Aug. 7, 1928.

UNITED STATES,

PATENT WILLIAM E. :SMITH, or rouenxnnrsm, NEW YORK. ASSIG'NOR or one-Harare HERMAN A. SCHATZ, 0F POUGHKEEPSIE, NEW' YO K. 4

vALvE GEAR.

Application filed November 9, 1925. SerialNo. 67,884. I

This invention relates to new and useful improvements in. valve operating mechanism, and more particularly to mechanism for controlling intake and exhaust valves of internal combustion engines.

The object of the invention is to p a simplevalve gear in-which the quick and accurate operation of the valves is insured and in which the valve stems are safeguard: ed against undue strains. With this object in view I provide a mechanism in which a single lever, spring, push rod, lifter and cam are required to operate the two valves. The construction is so provided as to permit the use. of short valvestems and relatively long valve guides. The leverarrangement which directly bears on the valves is .so providedthat upon the opening of either valve thereis no, resistance caused by spring pressure, eliminatingthus all side thrust on the valve stems. tween the valve stems and the actuating lever, whereby the objectionable noise and wear due to the hammering action is safeguarded against. A spring is used to maintain the valves closed, but the pressure of the spring is equalized between the two valves. When either valve opens, the resulting increase of pressure caused by the compression of the spring is automatically transferred to thestationary valve.v Y I These and other features of the invention will more clearly appear from the following detailed description ofa preferred emhodiment of theinvention and theappended claims. Y In the drawings a preferred embodiment of the invention is illustrated as applied to a single cylinder internal combustionengine of. the type disclosed in my copending applications Serial No.715',338, filed May 23, 1924 and No. 722,580, filed June 26, 1924. Fig. 1 is a vertical cross-section ofqtheen gine head illustrating the valve mechanism; Fig. 2 is a horizontal cross-section of half, of the valve actuating mechanism along line 2-2 of Fig. 1; Fig.8 is a top plan view of the valve actuating mechanism, the valve box being horizontally cut away along line 3-3 of Fig. 1; Fig. 4 is a side elevation" of the cam and rocker arm arrangement forming parts of thevalve gear and Figs.

5 and 6 are perspective views of details of the valve mounting. f A piston (not shown) operating within rovide Norclearance is required beof the lever 26 is enlarged thisTen'larged-portion is held the ball-shaped? cylinder 1 draws a mixture of airand va-.

porized gasoline from a vaporizing chamber 2.surrounding the cylinder 1,;through intake passage "3 and intake port 4-into? a compression chamber 5 provided-in. the cylinder head 6. After compressionsa'nd exa plosion,- the. residual gases. are expelled through 8 in the usual manner. The opening and closing of the ports 4 and 7 are controlled, respectively, by intake valve 9 andexhaust valvelO. These valves are providedwitlr. sloping shoulders adapted to register iwith taperedseats in the ports 4 and 7,;and with short stems, 11' and 12. The valve: stems pass through and, are vertically movable:

within guides constituted by f perforated bosses 13 and 14 in the head 6 above the ports 1 exhaust port 7 and exhaust channel' 7 4 and 7." The ends of stemsll anid '12 projecting through bosses 13 and 14 are internally screw-threaded," as indicated at 15,for l the purpose of receiving externally screwthreaded lugslsuch. as .16'pmjecting from shown inFig. 5, these forked heads. are provided with perforations. through which pi ns,19 and 20 pass. The middle-portions 'forked stem heads 17 and: 18.] As clearlyof these" pins are/squared, as indicated at,

21'inFig. 5, and are engaged. by 'jaws-22- and 23 provided at the ends of a lever" or. rocker arm 24, affording a gripping or clamping connection between the ends *oflever 24 and the-valve stems;

The central portion of the lever 24 is enlarged, as indicated at 25. (Fig. '3), and in alignment with this enlarged portion" an arm'26 projects downward substantiallyvatright angles from the lever.- The lever" 24%" is seated in an upright collar 27 of a'cup 28 (see Figs. 1. andfi) insuch a' manner that the arm 26 projects through the collar. 27 and cup 28 and the curved lower faces 29 and 30 of the lever lie within the notches 31 and 32 of the collar. The-ends of pin 33 projecting through the center of the lever 24'are seated-in the rectangular slots 34-and 35 of collar 27. The cup 28 and therefore head 6 bymeans of a coiled spring. 36 .surrounding the a'rm-26, the upper. end of the the lever 24 are spaced from the'cylinder' Y spring being seatedin the cup 28 andthe lower end; within a cavity 37 provided'in the 3 top of thefcylinder head. The low'er'part' at 38 and within projection 39 provided on a sleeve 40. The sleeve 40 is rigidly mounted on a shaft 41. The shaft 41 and sleeve 40 are on the outside of the cylinder head between the bosses 13 and 14, the contour of said space being illustrated in Fig. 2 at 42. The sleeve is held against longitudinal displacement between the flat side of the cavity 42 and a nut 43 provided on one end of shaft 41. The other end of the shaft projects to the outside of the cylinder head and is there fastened to one end of a crank 44. The free end of the crank 44 carries a pin 45 which is rotatably held within a sleeve 46. A rigid arm 47 projecting from the sleeve 46 is pivoted at its free end around a bolt 48 screwed in an embossing 49 of the cylinder head. In the opposite direction an arm 50 projects from the sleeve 46 and carries at'its end a clevis 51 of the push rod.

Push rod 52 is secured to lever 50 at clevis 51. As shown in Fig. 4, the push rod is in two sections held together by a turnbuckle 53 provided with left and right-hand thread for the purpose of adjustment. The lower end of the push rod is pivotally carried by a pin 54 in a boss 55 provided at the end of one arm or lifter 56 of a two armed rocker 57. With its two lifters 56 and 58 carrying bosses 55 and 59, respectively, the rocker 57 straddles a cam 60. The rocker is pivotally mounted by means of a bolt 61 on the motor, and is surrounded by a spiral spring 62, one end of which is fastened to the arm '56 at 63 and the other end to the motor at 64. The cam is rigidly mounted on the shaft 65 of a crown gear66, which meshes with a gear wheel 67 mounted on the crankshaft 68 of the motor. 1 v I Through the gears 67 and 66 the shaft 68 causes the double faced cam 60 to revolve in a clockwise direction. When the cam surface is not in contact with either roller 55 or 59, then the spring 62 is neutral. At this time both valves 9 and 10 are closed, being pressed against their seats by the coiled spring 36 through the agency of the lever 24.

As the cam turns to the right and moves the rocker 57 in a clockwise direction, the spring 62 builds up tension. The tension of this spring is so proportioned that at maximum speed it will overcome the inertia of the lifter or rocker 57, the push rod 52, and the lever 47-50. It would be possible to proportion spring 36 so as to perform all this work, but if this were done the entire mechanism would be subject to the increased power of the spring and would increase the wear on the valve mechanism. For this reason the spring 36 is so proportioned that its tension is sufiicient to operate the valve. the lever ,24 and the shaft 41. As the push rod 52 ascends it turns through the crank 44 the shaft 41, whereby the ball 89 is tilted to the left and through the agency of the arm 26 rotates the rocker 24 in a clockwise direction around a pivot point constituted by the stem head 17 and pin 19. This will permit the exhaust valve 12 to open. During the further revolution of the cam, the rockers 57 and. 24 will again reach the neutral position, and then by pressure of cam 60 againstthe roller 59, an intake position will be reached in which the arm 24 will be tilted in the 0ppos te direct-ion from the one illustrated in the drawing. At this time the pivot point of the arm is constituted by the stem head 18 and pin 20.

Owing to the proper proportioning' of the two coil springs and the provision of a single spring between the two valves, the valve stems are about an inch and a quarter shorter than would be necessary if the springs were appled to each valve in the usual manner. This, ofcourse, results in a saving of space, material, facilitates the manufacture, and reduces the tendency of warping of the valve stems. Furthermore, on opening either valve no resistance is offeredby spring pressure, each valve being free to open and close under the action of lever 24. Since the valve stems are lifted and permitted to dropvertically, there is no side thrust on the stems, which eliminates wear on the stems and the guides. A further feature of this construction resides 1n the possibility of eliminating the usual clearance between the valve'stems and the lever 24, avoiding thus the objectonable noise and wear caused by hammering action which would otherwise take place. Vith' both valves closed, the pressure of spring 86 is equalized between the two valves. When either valve opens, the resulting increase of pressure caused by the compression of spring 36 is automaticallytransferred to the stationary valve wh ch will insure tight seating thereof. Owing to this continuous transfer of energy from one valve to the other, the

spring 36 may be of low tension. It will be seen also that with this construction, it'will be impossible for both valves to be open at the same time, as one valve must open before the other closes. In the present construction the expansion of the valve stems or valves s nce, in the neutral position of the Ill) other parts does not affect the seating of the lever 24, they are always firmly held against their seat. If a clearance space were provided bet-ween the stem heads and the lever 24, then such space could be easily taken up by the expansion of the stems. Owing to the absence of springs directly applied to the valve stems, fluttering of the valves at high speed is eliminated.

The operating gear of the valves is enclosed within a cas ng 60 which is secured to the cylinder head 6 by means of'bolts 60*. The cooling by air of casing 60 is facilitated by. ribs 61. In order properly to lubricate the'valves and their 0 rating mechanism, a chamber 62 provided in. the top of casingBO is connected at 63 with'an oil' reservoir (not shown), preferably with the crank case of.

the engine. Th chamber 62 communicates through apertures64, 65, 66 with the valve casing 60, and owing to the pumping action of the valve stems, lubricant will be drawn into said chamber. Through the opening 65,

oil will flow. into a. cavity 67 provided in the enlarged section 25 of rocker arm .24, andthrough a longitudinal passage 68 inarm 26, within the head 38 of this arm. This will supply lubricant between head 38 and the ball 39. Oil will flow also through a channel 69 provided in the ball39 into a longitudinal channel 70 provided in' shaft 41, and then through a bore 71 to the bearing surface of pin 45. Oil dripping through apertures 64 and 66 will insure lubrication of the valve said valves, a lever engaging at its two ends the heads of said stems, a spring bearing against the centre of said lever, an arm pro- I ectmg from the centre of sa1d lever, and

means for rocking said lever by means of said arm around pivots constitutedby said stem heads.

3. In an internal combustion engine, intake and exhaust valves, stems for said valves, a spring-pressed arm engagingat-its two ends the heads of said stems, and meansv centrally located intermediate the ends of said arm for rocking said arm around pivots constituted by said stem heads.

4. In an internal combustion engine, intake and exhaust valves, stems for said valves, an arm engaging at its two ends the heads of said stems, a spring. placed under tension against the centre of said arm, and means for rocking said arm around pivots constituted by said stem heads.

5, In an internal combustion engine, a cylinder head, intake and exhaust valves therein, stems for said valves projecting through said head, an arm engaging at its two ends the heads of said stems, a spring placed under tension between the centre of said arm and said cylinder head, and means for rocking said arm around pivots constituted by said stem heads.

6. A valve gear comprising two valves, stems for said valves, a lever engaging at its two ends said stems, means for alternately opening and closing said valves through said lever, a. single spring cooperatingwith the midpoint of said lever and placed undei tension by the valve operating movement of said lever, and a mountingfor said spring and lever whereby the increase of pressure caused by the compressionof said springis transferred to the stationary one of said valves. 1 Y

:7. A valve gear comprising two valves,

stems for said valves, a single spring normally tending to maintain both of said valves in a closed osition, a lever pivoted at its two ends in said stems transmitting the I pressure ofsaid springthereto, .an'd means for rocking said lever.

8. A valve, gear comprising two valves,

stems for said valves, a single resilient means normally tending to maintain said valves in a closed position, a lever against which said resilient means exerts pressure, and gripping connections between the ends of said lever and said stems.

9. A valve gear comprising a valve having a stem, means including a lever torre ciprocating said stem, a spring bearing against said lever intermediate its ends, a gripping connection between one end of said lever and said stem, a pivot for the other end of said lever, and means for moving said pivot parallel with said stem but in the opposite direction. p

'10. A valve gear, two valves, means including a spring and a lever for operating said valves, a cam, a lifter cooperating therewith, a push rod connecting said lifter with saidlever, and a normally neutral springv bearing against said lifter so proportioned that when placed under tension it tends to overcome the inertia of said lifter and push rod.

the two ends of which are attached to the two valves for operating said valves, a spring pressing against the lever intermediate the ends thereof for normally keeping both valves closed, a cam, a lifter cooperating therewith, a push rod connecting said lifter with said lever, and a second spring placed under tension only when said cam actuates said lifter.

12. A valve gear, two valves, stems for said valves, valve-operating mechanism comprising a lever engaging at its two ends said stems, a spring bearing against the centre of said lever, ashaft for rocking said 11. In a valve gear, two valves, a lever,

lever, a earn, a lifter cooperating therewith,

a push rod connecting said lifter with said shaft, and a second spring opposing the movement of said'lifter, said springs being so proportioned that they jointly tend to overcome the inertia of said valve-operating mechanism. V

13. In a valve gear, two valves, stems for said valves, alever engaging at its two ends said stems, a spring bearing against the centre of said lever, a shaft for rocking said lever around pivot points constituted by said stems, the tension of said spring being proportioned to operate said valves and to overcome the inertia of said lever and shaft, a cam, a lifter cooperating therewith, a push rod connecting said lifter with said shaft, and a normally neutral spring connected with said lifter so proportioned that when placed under tension it tends to overcome the the inertia of said lifter and push rod.

14L. In an internal combustion engine, a cylinder head, intake and exhaust valves therein, stems for said valves projecting through said head, a lever engaging the heads of said stems at its two ends, a spring placed under tension between the centre of said lever and the cylinder head, "a shaft" for rocking said arm around plvot points constituted by said stem heads, the tension of said spring being proportioned to operate said valves and to overcome the inertia of said lever and shaft, a cam, a lifter ceoperating therewith, a push rod connecting said lifter with said shaft, and a normally neutral spring connected with said lifter so proportioned that when placed under tension it tends to overcome the inertia of said lifter and push rod.

In testimony whereof, I have signed my name to this specification this November, 1925.

WILLIAM F. SMITH.

2nd day of i

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