US2330719A

US2330719A - Rocker arm support

Info

Publication number: US2330719A
Application number: US376161A
Authority: US
Inventors: Floyd F Kishline
Original assignee: Nash Kelvinator Corp
Current assignee: American Motors Corp
Priority date: 1941-01-27
Filing date: 1941-01-27
Publication date: 1943-09-28
Anticipated expiration: 1960-09-28

Description

Patented Sept. 28, 1943 Floyd F. Kishline, Kenosha Wis; assignor to Nash-Kelvinator Corporation, Kenosha, Wis., a

corporation of Maryland 7 Application January 27, 1941, Serial No. 376,161

' eo aims. (or ice-90) This invention relates to rocker arm supports and hasparticular reference to means for supporting a rocker arm shaft upon the head of a valve-in-head motor; i

In the past it has been the practice to support the rocker arm shaft ofa valve-in-head motor directly upon the cast iron head of the motor. Due to the differentials in temperature existing between the valve stems and the portion of the headwhich supports the rocker arm shaft and due to the differentials between the co-eficients of expansion of the steel valves and the cast iron head, the clearance between the end of the valve stems and the rocker arms mounted on the rocker arm shaft has been subject to considerable change depending upon the temperature at which the motor is operating. Ifv the motor i adjusted with proper clearance when cold, it will have insufficient clearance when the motor becomes heated. If, on the other hand, the motor is adjusted for proper clearance when operating at a 'high temperature, it .will be noisy in operation when operating at a low temperature such as exists when the motor is started. As a result, it has been the general practice to adjust the valves and rocker arms of the motor to obtain an average clearance which is correct for neither hot nor cold operation of the motor.

It is an object of this invention to provide a motor in which the valves may be adjusted for K proper clearance at all operating temperatures of the motor.

It is another object of this invention to provide means for compensating for the expansion of the valve stems of a motor when the motor becomes heated. p l v It is another object of this invention to provide means for supporting the rocker arm shaft of a motor, which means will expand as the motor is heated to compensate for expansion of the valve stems of the motor. l e

Other objects and advantages of this invention will be apparent from. a consideration of the following description and claims and the attached drawing, of which there is one sheet, and in which-.-

Figure 1 represents a-plan view of a portion of the head of a valve-in-head motor;

Figure 2 represents a vertical transverse sectional View, partially broken away, taken along planes indicated by the broken line 2'-,2 in Fig- Illustrated in the drawing isa motor of the valve-in-head type having a motor block I0 within which is formed a series of cylinders, one of which is illustratedkat l2. The block lllis provided with a top wall i4 and a side wall l6. Spaced from the side wall [6 is a false wall l8 which is connected to the sidewall US by a series of ribs, one of which is illustrated at 20. Positioned on top of? the block ii] is acylinder head casting generally indicated at 22 which is provided with an upper wall 24 and a lower wall 26. The upper and lower walls of the head casting 22 are connected'by-ta side wall 28 and a spaced false wallfii) which is arranged to overlie the false wall. [Biormed on the cylinder block I!) andwhich is connected to the side wall 28 by a ure 1 and looking in the direction'of the arrows; v

and l Figure 3 represents a diagrammatic view ofwthe valve and rocker arm structure shown in Figure 1.

series of ribs 32 positioned along the top and bottom ofthe false wall 30. The bottom wall 26 is recessed upwardly as'at 34 over each of the cylinders l2to form a combustion chamber 36, and the upper portion of the recessed wall 34 is apere tured and connected to suitable intake and exhaust ducts, one of which is illustrated at 38. Cylindrical columns 48 are integrally cast with the head 22 and extend between the top wall 24 and the ducts 38. The space between the

walls

24, 26, 28 and other. side wall (not shown) forms a cooling jacket 4| through which a cooling medium may be circulated around .the combustion chambers 34, ducts 38 and columns 4E1.

Th columns 48 each define a vertical passage arranged to receive a valve guide 42 within which the stem 43 of a valve 44 is arranged to slide to control the flow of fuel mixture and exhaust gases through the ducts 38. g l

The side wall 28 of the head casting has a series of vertical bosses 45 formed therealong, which bosses extend from the top wall 24 to the lower wall 26. The bosses 45 each'define a vertical cylindrical well 46 which extends downwardly to a point just overrthe lower wall 26 of the head. The wall 26 below the well 46 is apertured to pass a stud-bolt 48 which has its lower end threaded into the top wall I4 of the cylinder block [9 and its upper end projecting upwardly into the well 46. The upper end of the stud bolt 48 is threaded to be received in the lower end of a hollow cylindrical column 50 which may be made of brass or some substance having a, higher co-efiicient of xpansion than cast iron and steel. It will be noted that the column 50 has an outside diameter which is slightly smaller than the diameter of the well '46 and that it is provided with an annular flange 52 near its upper end which is arranged to close the upper end of the well 46. Just abovethe .fiange 52 the column 50 has a hexagonal head 54 formed thereon so that it may be screwed tightly onto the upper end of the stud bolt 48. The lower end of the column 50 bearing against the bottom or the well 46 serves to hold the head 22 on the block l0.

The upper end of the valve stem 43 is provided with annular grooves 58 which are arranged to engage mating ribs formed on the inside of a split ring 58, The outer surface of the split ring 58 is tapered downwardly to fit within a tapered aperture formed in a valve spring seat 60 so that the spring seat 60 and split ring 53 will restrain the upper end of a valve spring 02. relative to the upper end of the valve stem 43. The valve 44 is thus held in closed position until the valve stem is pushed downwardly by a rocker arm [it provided with a nose 66 which bears against the upper end of the valve stem 03.

The rocker arm 04 is pivotally supported in termediate of its ends upon a rocker arm shaft 68 and is provided with a generally fiat outer end l which is provided with a tapped aperture for receiving the threaded pin 12. The lower end of the pin it is provided with ahemispherical head '14 which is received in a hemispherical socket formed in a fixture 76 carried on the upper end of a push rod E8. The push rod extends downwardly between the side walls 28 and i6 and the false walls. and 18 to suitable cam mechanism (not shownlpositioned in the motor block It. The position of the threaded pin l2 relative to the rocker arm 64 may be adjusted to determine the clearance between the nose 68 and the valve stem t3 by turning the pinin the threaded aperture and locking the pin of the lock nut 80. The rocker arm shaft 58 is supportedin a series of rocker arm support blocks, one of which is illustrated at 82. The support blocks 82 are provided with upper and lower parallel surfaces 84 defining apertures through which a cap screw tt may be passed and threaded into the internally tapped upper end of the column to secure the support block 02 on the upper end of the column. It will be noted'that the rocker arm shaft 68 is provided with vertical apertures ar ranged to pass the cap screws 86 andthat the rocker arm shaft is hollow so that lubricant may be pumped therethrough to lubricate the bearing surfaces between the rocker arms and the rocker arm shafts.

In operation of the motor, the valves to and valve stems to will become heated to a relatively high temperature while the columns 50,;which are further removed from the combustion chambers 30, will not be raised to such high temperature. The-increased temperature of thevalve stems 33 will cause them to expand in length by an amount determined by their co-efficient of expansion, initial length and the average rise in temperature of the valve stems. This increase in length tends to closethe clearance between the nose of the rocker arms 06 and the upper end of .the valve stems 43. T0 counteract this increase in length in the valve stems 43, the columns 50 are made of some material such as in place by means brass which has a higher co-efficient of expansion than the steel materialwhich formsv the valve stems G3. ,The higher co-efficient of expansion of the columns 50 causes the length of the columns 50 toexpand sufiiciently to raise the rocker arm' shaft support blocks 82 and the rocker arm shaft 80 to, compensate forthe elongation of the .valvestems 43.; It may be assumed that the length of the push rods 18, while they may expand slightly, will remain approximately the same length as the distance between the ball. heads M and the cam mechanism due to the slight expansion of the cast iron which forms the cylinder block I 0 and the head 22. The push rods 18 may therefore be ignored in designing the columns 50.

By way of example and considering the diagrammatic view shown in Figure 3, let it be assumed that the valve M will operate through a temperature range of 600 while the column 50 will operate through a temperature range of only 200. These temperature ranges can, of course, be measured in any motor. Assuming further that the length of the valve stem indicated at V is six inches and that it is made of steelhaving a co-eificient of expansion equal to .00000636 inch, per inch of length, per degree of temperature change; then the valve may be expected to increase in length by an amount, e, equal to .00000636 6 600 or .01 inch when the motor becomes heated.

Assuming the ratio of the right end of the rocker arm 6%, indicated as B, to the total length of the rocker arm, indicated as A plus B, to be .75; then with the increased length, e, of the valve equal to .01, the rocker arm shaft 08 should be raised .'l5 .0l or .0075 inch indicated at E to compensate for the increased length, 6, in the valve 04.

Now assuming that the material used to form the column 50 is brass having a co-emcient of expansion of .00000957 inch, per inch of length, per degree of temperature change and remembering that it is to operate through a temperature range of 200 and that it is to increase in length by .0075 inch; then the initial length of the column 59 at the temperature of the motor when cold should equal .0075 divided by 200 .00000957 or, roughly, 7.83 inches.

It will be understood that the above figures are given by way of example only and that other materials may be used in the valve stem 3 and column Eliland that different valve lengths and column lengths may be used. By means of this invention the clearance between the nose 60 of the rocker arm 64 and the upper end of the valve stem 43 may be properly adjusted to the most desirable figure either while the motor is hot or cold and this clearance will remain the same as the valve M expands and contracts during different operating temperatures of the motor.

1 While I have described my invention in some detail, I intend this description to be an example only and not as a limitation of my invention, to which I make the following claims:

1. In an internal combustion engine, a cylinder block, a head casting having valve mechanism therein and defining a cooling jacxet, a boss extending from the top of said head to the bottom thereof and through said cooling jacket, said boss defining a well open on the top of said head. a stud bolt threaded into the top of said cylinder block and projecting into the bottom of said well, a nut having an elongated lower end threaded on the upper end of said stud bolt and a head portion positioned above the top of said head casting, a rocker arm shaft supported upon the top of said'nut and a rocker arm journaled on said shaft for operating said valve mechanism, said nut being formed of a material having a higher co-efficient of expansion than said valve mechanism.

2. In aninternal combustion engine, a cylinder block, a head casting having valve mechanism therein and defining a cooling jacket, a boss extending from the top of said head to the bottom thereof and through said cooling jacket, said :boss defining a well open on the top of said head, a stud bolt threaded into the top of said cylinder block and projecting into the bottom of said well, a nut having an elongated lower end threaded on the upper end of said stud bolt and a head portion positioned above the top of said head casting, a rocker arm shaft supported upon the top of said nut and a rocker arm journaled on said shaft for operating said valve mechanism, said elongated portion of said nut being of smaller diameter than said Well and being formed of material having a higher co-efiicient of expansion than said valve mechanism.

3. In an internal combustion engine, a motor block, a head casting having spaced upper and lower Walls, means defining a recess through said upper wall to said lower wall, a stud bolt having a threaded connection with said cylinder block and projecting into the bottom of said recess, a nut having a head portion positioned above the top wall of said head and an elongated portion threaded onto said stud bolt and bearing against the bottom of said recess, a valve positioned in said head casting and having a stem projecting above the upper wall thereof, a rocker arm shaft supported upon the upper end of said nut, and a rocker arm journaled on said shaft and arranged to operate said valve, the elongated portion of said nut being formed of a material having a vhigher co-efiicient of expansion than said valve stem.

FLOYD F. KISHLINE.