US1554306A

US1554306A - Compensating rocker arm support

Info

Publication number: US1554306A
Application number: US671687A
Authority: US
Inventors: Caleb E Summers
Original assignee: General Motors Research Corp
Current assignee: General Motors Research Corp
Priority date: 1923-10-30
Filing date: 1923-10-30
Publication date: 1925-09-22
Anticipated expiration: 1942-09-22

Description

Sept. 22. 1925.

I C- E. SUMMERS COMPENSATING ROCKER ARM- SUPPORT Filed Oct. 30. 192.5 2 Sheets-Sheet 1 [11 ZJ'E'JZZ 51- (.94!- 13W.

Sept. 22. 1925.

c. E. SUMMERS COMPENSA'IING ROCKER ARM SUPPTSRT Ffiled on. 30, L923 2 Sheets-Sheet 2 .[JZZTEJZZDT Maw,

' Patented Sept. 22, 1925. L

QFFICE;

CALEB n suumnasornmrron, 01110, Assurance ToGENERA MOTOR-S RESEARCH CORPORATION, DAYTON, OHIO, ,A CORPORATION OF DELAWARE.

comrnnsn'rm 00mm Ann ,surr oa'r.

Toal l whom it may concern:

Be it known that LCAL E. S M E S, a

citizen of the Unitedjstatesof America,

residing at "Dayton, county of Montgomery,

Statemof Ohio, have invented, certain new and useful Improvements in Compensating RockerArinSupports, of which the following is a full, clear, and exact description.

' "This invention: relates to internal combustion engines including valve mechanism of the overhead type, -that is, the valves are operated by means of rocker arms mounted above the cylinder and by puslrrodse xtending'along the cylindcrzmd into the crank ca e, '1. V

One of the objects of the present invention is to. compensate. for changes in ,temperature to' which the valve mechanism is subjected "in order that throughout the range of engiheoloeirating temperatures the clear: ance between the rocker farm and cooperat ing parts will lie-maintained practically constant." In order to accomplish this object, one form of the invention consists in subjecting the push. rod to the-heatedair.s1 1rrounding the en'ginecylinderand in using a push rod which is substantially longer than the engine cylinder in order that the total expansion of the push rod; will besubstautially thesame i as, the totalexpansion of the. cylind er. The push rod extends a distance above the 1 cylinder head and operates a rocker} arm which is pivoted Qa-bove the c'ylinderfhead upon. a? support which is mounted upon the cylinder head. The I invention provides means "fort c ooling this support, forthe rocker arm so as to minimize theaelongation of this support dueflto the increase in engine temperature wheninoperation.

Other further objects and advantages of the present invention wilhbe apparent, from the following description, reference being had to the accompanying. drawings, wherein a preferred embodiment of one torm of. the present invention is clearly shown.

, In the drawings: 3 v

Fig. l is an end'view ofan engine partly in section which includes .a form of the; presentinvention. i x V n Fig. 2 is a fragmentaryplan v'iew of the engine shownvin .1.' I v y a: 7 l Fig; 3 is a fragmentarysectional view showing a modified formof theinventiom In the drawings, indicates the cranke f a al om es enie n sue- Application. filed October 30, 1923, Serial No. 671,687. I

porting one or 'more cylinder 21 provided with cooling ribs or'fins 22. One form of such cylinder is disclosed in the copend ing application of C Kettering, Serial $10,514,014, filed N ovember9, 1921. To the head end of cylinder 21 there is attached superstructure 23 which provides an intake passage 24 and an exhaust passage 25, and guides jforthe stems 26 of the engines valves, one of which is indicated in dotted lines in Fig. 1. Asshown in Fig. 2 there is onesu perstructure23 for each pair of cylinders. Superstructure 28 is thermally insulated from the head of the cylinder 21 by means of a-nonconducting gasket 27. i

A portion of the fins 220 f each cylinder s ur eun d y a ra b 8 w ioh merge in o a a a l? manif01d2 clos d at ne nd a d h'a na he eth r n p n'a d communicating with anengineoperated air circulating fan 30 which is driven hylthe engine by means of pulleys 31 and 32 and a belt 33. When the fan operates, air is caused to circulate upwardly throu h the heat dissipating. fins22 to carry away heat by the. fins from the cylinder walls. The heated air passing upwardly through the several draft tubes 28' is conducted through the air manifold 2%) to the fan 30 'wliich lexpels the air between its ,fan,blad es iThe val e o he e gine. are'ope ted' y mechanism whichiinclujdes in each case a gamAO, located on cam shaft 41 operated by the engine, apush r0d142 operated by-cam i0 and rocker ar1n,43 whicl1 .is mounted on a rocker arm shaft 44. ,'I he shaft 4i is supported above] the e11ginecy1inder by means which -is ,,not subjected to the amount of temperaturechange during engine o era tion to whichfsuch parts as the engine cylinder-and push rods are subjected. This means forsupporting the rockerfshaft Ailin- Qludes a tubular pedestal vwhich is at- .tachedtothe superstructure 23 .byimeans of a ;'stud- 51 attached: thereto, and by means of nut; 52 threaded .on the ,iipjper end of stud L51. A. non-conducting washer 58 assists. in

thermally insulating the pedestal 50 from partf23. A spring washer 59 is located between the nut 52and pedestal 50. The stud 51 extends through the tubular passage .53 providedwithin the pedestal 50 and is re,- ceivediby; anotch provided in the rocker tttq-r ere t i h o t e e in the apertured shaft supporting portion 54 with which the pedestal 50 is provided. The passage 53 is provided with outlets at 55 and 56 and with an inlet pipe 57 which extends through the air manifold 29 and outside the draft tube 28.

Rotation of the cam shaft 41 produces reciprocation of the push rod 42, oscillation of rocker arm 43 and reciprocation of the engine valve 26. The drawings show a conventional valve return spring 60 which yieldingly maintains the valve on its seat and the lower end of the push rod in engagement with the cam 40.

The clearance between the rocker arm 43 and the valve is adjusted at the ball and

socket joint

61, 62 in the usual manner by adjusting the screw 63 and locking the screw in position by a lock nut 64; This adjustment of clearance is usually made when the engine is cold. Since the engine cylinder is heated during engine operation to a higher temperature than the push rod 42, the cylinder tends to expand faster than the push rod.

In order that the valve clearance be maintained constant throughout the range of engine temperature increase, it is desirable that the total expansion of the push rod should be substantially equal the total expansion of the cylinder and that the total expansion of the pedestal 50 be negligible. The push rod 42 is therefore located in the path of air which circulates over the engine fins. Gertain of the fins such as fins 22 in Fig. 2 are shorter radially than other fins so that the push rod may be located relatively closer to the fins and to the engine cylinder wall. In this way the push rod is subjected to the heat dissipated from the cylinder wall by means of the cooling fins and circulating air. hile the temperature of the push rod 42 may not be as great as the temperature of the hottest part of the cylinder walls yet the temperature of the push rod will be substantially increased during engine operation. By making the push rod substantially longer than the engine cylinder and by making it of material having the desired coefiicient of expansion the total endwise expansion of the push rod can be made substantially the same as the total lengthwise expansion of the cylinder.

The interior of the pedestal 50 is in direct communication with air outside of the draft tube 28 and the air manifold 29 so that the operation of the fan 34 causes relatively cool air to enter the pedestal 50 through passage 57 and to be drawn out through passages 55 and 56. In this manner the temperature of the pedestal 50 is maintained substantially below that of the engine cylinder and superstructure. The nonconducting washer 58. located between the pedestal 50rand the superstructure 23 tends to prevent heat transfer directly from the superstructure. The stud 51 may become hotter than the pedestal 50 and therefore expand lengthwise to a greater degree. Expansion of the stud 51 may take place without effecting expansion of the pedestal 50 because the stud is permitted to move upwardly relative to the rocker arm shaft 44. This expansion of the stud 51 will tend to lift the nut 52 but pressure between the nut 52 and the upper end of the pedestal 50 is maintained through the spring washer 59.

By maintaining the pedestal 50 relatively cool the endwise expansion thereof can be rendered substantially negligible. Consequently, the vertical distance between the superstructure 23 and the rocker shaft 44 changes but a slight amount. Since means have been provided to maintain a pedestal of substantial length relatively cool, the greater length of the push rod as compared with the engine cylinder can be taken advantage of in the matter of compensating for changes in temperature, although the engine cylinder may be heated to a greater degree than the push rod.

A modified form of the invention is shown in Fig. 3. A tubular pedestal is employed having an inlet pipe 71 leading into a central passage 72 connected with outlets 73 and 74. The pedestal 70 supports the rocker shaft 44 centrally of the passage 72; and the stud 51 extends through a hole provided in the shaft 44. The pedestal 70 is maintained cool by air entering the passa e 71 and leaving through the passages (3 and 74.

lVhile the form of embodiment of the invention as herein disclosed, constitutes a preferred form it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

\Vhat is claimed is asfollows:

.1. An engine comprising, in combination, a cylinder, avalve seated adjacent the cylinder head, a rocker arm mounted for operating the valve, means for supporting the rocker arm at a substantial distance from the cylinder head, a push rod for operating the rocker arm, means for subjecting the push rod to heat developed by the engine, and means for maintaining the temperature of the rocker arm support below that of the push rod during engine operation.

V 2. An engine comprising, in combination, a cylinder, a valve seated upon the cylinder head, a rocker arm support extending from the cylinder head, a rocker arm supported thereby for operating said valve, a push rod substantially longer than the cylinder extending lengthwise thereof, means for circulating a fluid around the cylinder to cool the same and to heat the push rod, and

means for maintaining the rocker arm support at a temperature lower than that of the push rod during engine operation.

3. An engine comprising, in combination, a cylinder provided with cooling fins, a valve seated upon the cylinder head, 'a rocker arm support extending from the cylinder head, a rocker arm supported thereby for operating said valve, a push rod suba cylinder provided With cooling fins, a

- valve seated upon the cylinder head, a rocker arm support extending fromthe cylinder head, a rocker arm supported thereby for operating said valve, apush rod substantially longer than the cylinder ext-ending length- Wise thereof, and adjacent the fins, means for circulating air about the finsand push rod to cool the cylinder and heat the push rod, and means for subjecting the rocker arm support to air which is cooler than the air heated by engine operation.

5. An engine comprising in combination, a cylinder provided with cooling fins, a valve seated upon the cylinder head, a rocker arm support extending from the cylinder head, a rocker arm supported thereby for operating said valve, a push rod substantially longer than the cylinder extending lengthwise thereof, and adjacent the fins, an air duct enclosing a portion of the push rod and fins, suction fan communicating with the air duct, and a duct com municating with the fan for subjecting the rocker arm support to air which is cooler than the air heated by the engine. 7

In testimony whereof I hereto'afiix my slgn ature.

' CALEB E. SUMMERS.