US1948414A

US1948414A - Valve actuating mechanism

Info

Publication number: US1948414A
Application number: US465474A
Authority: US
Inventors: Harold D Church
Original assignee: White Motor Co
Current assignee: White Motor Co
Priority date: 1930-07-03
Filing date: 1930-07-03
Publication date: 1934-02-20
Anticipated expiration: 1951-02-20

Description

Feb. 20, 1934. H. D. CHURCH VALVE ACTUATING MECHANISM Filed July 3, 1930 INVENTOR H.D. CHURCH A TTORNE V Patented Feb. 20, 1934 UNITED STATES VALVE ACTUATING MECHANISM Harold D. Church, Cleveland, Ohio, assignor to The White Motor Company, Cleveland, Ohio, a

corporation of Ohio Application July 3, 1930. Serial No. 465,474

5 Claims.

This invention relates to valve actuating mechanisms of the type employed in internal combustion engines.

It is an object of this invention to provide a simple and efficient valve actuating mechanism which will automatically adjust itself to compensate for expansion or contraction of its parts and the parts of the structure which supports it.

It is a further object of this invention to provide a valve actuating mechanism in which the parts are constantly maintained in engagement, and which for that reason is noiseless in its operation.

It is a further object of this invention to provide a valve actuating mechanism embodying a fiuidic compensating apparatus in which the fluid is subjected to a relatively small force as compared to the thrust imposed upon the parts of the mechanism which transmit the valve opening movement.

Other objects and attendant advantages will appear in the following description when read in connection with the accompanying drawing, in which:

Figure l. is a transverse section of an internal combustion engine of the overhead valve type provided with a valve actuating mechanism embodying this invention.

Figure 2 is an enlarged fragmentary rear elevation of the valve push rod shown in Figure 1.

Figure 3 is an enlarged section taken on line 3-3 of Figure l.

Figure 4 is an enlarged vertical section of the apparatus mounted on the left hand side of the engine illustrated in Figure 1, and.

Figure 5 is an enlarged section of a modification of the apparatusillustrated in Figure 4.

Referring to the drawing, the numeral 10 indicates an exhaust passage formed in the cylinder head 11 of the engine therein illustrated. The exhaust passage 10 is controlled by a valve 12 mounted in a guide 13 set in the upper part of the cylinder head. The valve 12 cooperates with a seat 14 formed in the lower surface of the cylinder head, and is provided with closing springs Mounted in the side of the crankcase 16 of the engine there is a cam shaft 17 formed with a bore 18 which forms part of a lubricating system of the type disclosed in United States Patent Number 1,265,145. This shaft is driven from the engine crank shaft by means of a driving connection (not shown) and operates the valve 12 through the instrumentality of an integrally formed cam 19, a tappet 20 mounted in a guide 21 afiixed in the lower wall of the engine cylinder block 22, an upwardly extending push rod 23, and a rocker arm 24 journalled on a shaft 26 mounted on the upper end of the cylinder head.

The push rod 23 is constructed of an upper secso tion 23a and a lower section 231) connected together by a telescopic hinge joint 23c; and is formed with a spherical lower end which fits within a complementary seat in the tappet, and with a spherical recessed upper end which re- 5 ceives the spherical lower end of an adjusting screw 27 mounted in the associated rocker arm 24.

The screw 27 is so adjusted that the distance between the lower end of the screw and the tappet 20 with the valve 12 closed is less than the extended length of the push rod. The push rod is maintained in engagement with its seat in the tappet 20 and with the superadjacent screw 27 by means of a rod 28 urged in a direction to extend the push rod by means of a spring 29 mounted in a cylinder 30 secured to the outer wall of the cylinder block. The inner end of the rod 28 is pivotally connected to the joint of the associated push rod by means of a clevis 31 and a bolt 32, the latter of which extends through the pivotal center of the joint 23c and the arms of the clevis. The opposite end of the rod 28 is pivotally supported in a spherical recess formed in the outer face of a piston 33 mounted within the cylinder 30 intermediate the spring 29 and the end of the rod.

Mounted on the end wall of the cylinder 30 there is a member 34 provided with a chamber 35 which communicates with the interior of the cylinder by means of ducts 36 and 3'? formed respectively in the end of the cylinder and the abutting wall of the member. Formed in the upper end wall of the member 34 there is a duct 38 which is supplied with oil under pressure, from a manifold 39 in cylinder block by way of a laterally extending pipe 40. Communication between the chamber 35 and the duct 38 is controlled by a valve 41 pressed in the direction of its seat at the lower end of the duct by means of a spring 42 incapable of maintaining the valve closed against the pressure of the oil in the duct. 7

The manifold 39, in addition to supplying oil to the duct 33, supplies oil to the joint 230 of the push rod through a duct 43 formed in the upper wall of the cylinder block. It receives oil from the bore 18 in the engine cam shaft by way of a radially extending duct 44 formed in the cam shaft, a laterally extending duct 45 formed in a web of the crank case, and a pair of vertically extending

ducts

46 and 47 formed respectively in the side walls of the crank case and cylinder block. The

duct 44 acts to meter the flow of oil to the manifold by intermittently connecting duct 45 with the bore 18 of the cam shaft, and is so designed that the oil delivered to the manifold 39 is slightly in excess to the oil which flows out of the same. The excess oil delivered to the manifold 39 flows upward through a pipe 48 into the interior of the cylinder head, and from there downward into the crank case through the push rod opening 49 and an aperture 50 formed in the abutting walls of the cylinder block and crank case, the transient oil within the pipe 48 acting as a constant gravity head upon the oil within the manifold 39.

Assuming that the chamber 35 and the cylinder 30 has been filled with oil from the manifold 39 the operation of the valve actuating mechanism is as follows:

During the opening and closing periods of the valve 12, the forces imposed upon the push rod 23 tend to decrease the angle between the upper and lower section thereof to cause an outward movement of the joint 230. The outward movement of the joint is resisted by the spring 29, and the oil confined within the cylinder 30 and the chamber 35, the valve 41 having been closed prior to the valve opening movement by its spring 42. The piston 33 is so designed that a small amount of oil will leak past its sides during the valve opening and closing periods, the leakage being sumcient to allow a slightly greater bontraction of the push rod than is necessary to compensate for the greatest possible expansion that could occur in the valve mechanism during any one valve cycle. This leakage requires that the valve 12 be brought into engagement with its seat prior to that point in the valve cycle in which the tappet 20 is brought to rest on the base circle 19a of the cam 19 and thereby insures against the valve being held open during that period in which it is intended to be closed.

Following the seating of the valve 12 and until the tappet 20 is brought to rest on the base circle of the cam 19, the push rod is extended by the spring 29 through the instrumentality of the intermediately disposed piston 33 and the rod 28 maintaining the various parts of the valve actuating mechanism in active engagement. This extension of the push rod by the spring 29 causes a forward movement of the piston 33, and the pressure having been removed from the oil at the 1 by its closing spring 42, the pressure on the different sides of the valve then being equal.

It will be seen from the foregoing description that the valve actuating mechanism will automatically adjust itself during each cycle to compensate for expansion or contraction therein, the adjustment being eifected through a successive contraction and expansion of the valve push rod which produces a resultant increase or decrease in the operative length of the valve actuating i mechanism equal to the change in the operative length of the mechanism caused by expansion or contraction of its parts and the associated parts of the engine.

To insure against damage to the valve actuating mechanism, should the cylinder 30 and the associated chamber 35 become entirely or partially depleted of oil, the cylinder is provided with a shoulder 51 so coordinated with the piston 33 as to prevent a decrease in the length of the push rod in excess to that required to prevent the valve being held open during that period in which it is intended to be closed by expansion of the valve actuating mechanism.

The mechanism illustrated in Figure 5 comprises a cylinder 52, a cylindrical member 53, a valve 54, a valve spring 55, a piston 55, and a spring 57 which respectively correspond to the parts 30-, 35, 41, 42, 33 and 27 of the apparatus illustrated in Figure 4. The cylinder 52 is constructed'with a tubular extension 58 formed with a flange 59 by which the mechanism is secured in place with the oil receiving end of the cylinder lowermost. Mounted in the extension 58 there is a plunger 60 formed with an inclined face which bears against the inclined upper face of the piston 56. The plunger 60 is formed with a spherical recess which receives the spherical outer end of a rod corresponding to the rod 28, and with a system of

ducts

61, 62 and 63 which provides an outlet to the interior of the cylinder block for the oil passing the piston 56.

The mechanism, just described, operates in the same manner as the one illustrated in Figure 4, except that the thrust of the push rod is transmitted to the piston by the intermediary plunger 60 instead of directly by the rod connected to the push rod.

Although the foregoing description is necessarily of a detailed character, in order that the invention may be completely set forth, it is to be understood that the specific terminology is not intended to be restrictive or confining and that various rearrangement of parts and structural details may be resorted to without departing from the scope or spirit of the invention as herein claimed.

I claim as my invention:

1. In an internal combustion engine, the combination of a cam, a spring pressed valve and means for transmitting thrust between said cam and valve including a member comprising a pair of pivoted angularly related sections arranged to move together to transmit the thrust of said cam and to tend to move angularly with respect to each other to vary the operative length of said member under a component of the thrust of said cam, means including a fluid column arranged to receive and resist the thrust of said pivoted sections tending to produce relative angular movement thereof, and means for increasing the length of said column of fluid upon the removal from said sections of all stress incident to the opening and closing of the valve.

2. In an internal combustion engine, the combination of a cam, a spring pressed valve, a push rod for transmitting thrust from said cam to said valve comprising a pair of pivoted angularly related sections, a member pivoted to said push rod and arranged to be moved laterally by relative angular movement of said sections and a brake associated with said member for normally resisting such movement.

3. In a valve actuating mechanism, a train of elements transmitting the valve opening and closing movements including a member movable with the remaining elements in said train to transmit the valve opening and closing movements, and separably movable to vary the operative length of said train, said member being so mounted that it is impelled to move in a direction to decrease the operative length of said train of mechanism by the thrust imposed thereon during the valve opening and closing periods, and being so arranged with respect to the other elements of said train that the force imposed thereon to overcome the resistance offered to its movement in the aforesaid direction is less than the thrust transmitted by said train, a brake retarding movement of said member in a direction to decrease the operative length of said train, and offering sufiicient resistance to insure the transmission by said train of the thrust necessary to valve actuation, and means for moving said member in a direction to increase the operative length of said train upon removal from said train of all thrust incident to the opening and closing of the valve.

4. In a valve actuating mechanism a train of elements transmitting the valve opening and closing movements including a member movable with the remaining elements in said train to transmit the valve opening and closing movements, and separably movable to vary the operative length of said train, said member being so mounted that it is impelled to move in a direction to decrease the operative length of said train by the thrust imposed thereon during the valve opening and closing periods, and being so arranged With respect to the other elements of said train that the force imposed thereon to overcome the resistance offered to its movement in the aforesaid direction is less than the thrust transmitted by said train, a fluid brake for re tarding movement of said member in a direction to decrease the operative length of said train, said fluid brake comprising a body of fluid placed under pressure in resisting the movement of said member in a direction to decrease the operative length of said train, means through which fluid from said body of fluid slowly escapes when said body of fluid is placed under pressure as aforesaid, and means for increasing said body fluid when the pressure imposed thereon by said member is removed.

5. In a valve actuating mechanism a train of elements transmitting the valve opening and closing movements including a member movable with the remaining elements in said train to transmit the valve opening and closing movements, and separably movable to vary the operative length of said train, said member being so mounted that it is impelled to move in a direction to decrease the operative length of said train of mechanism by the thrust imposed thereon in transmitting the valve opening and closing movements, and being so arranged with respect to the other elements of said train that the force imposed thereon to overcome the resistance offered to its movement in the aforesaid direction is less than the thrust transmitted by said train, a fixed part located adjacent said train, a fluid brake mounted upon said fixed part and designed to retard movement of said member in a direction to decrease the operative length of said train, said fluid brake comprising a body of fluid placed under pressure in resisting the movement of said member in a direction to decrease the operative length of said train, means through which fluid from said body of fluid slowly escapes when said body of fluid is placed under pressure as aforesaid, and means for increasing said body of fluid when the pressure imposed thereon by said member is removed.

HAROLD D. CHURCH.