US2112045A

US2112045A - Seal for combustion engines

Info

Publication number: US2112045A
Application number: US14433A
Authority: US
Inventors: Samuel R Puffer
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1935-04-03
Filing date: 1935-04-03
Publication date: 1938-03-22
Anticipated expiration: 1955-03-22

Description

l March 22, 1938. g s. R. PUFFER SEAL-FOR COMBUSTION ENGINES Filed April 3 1955 Figi 50a l5 `l7 invento@ `Sammel RPuffeF, b5

His Attoweg.

Patented Mar. 22,

2,112,045 VSEAL FOR. COMBUSTION ENGINES Samuel VIt. Puier, General Electric New York Saugus, Mass., Company,

assignor to a corporation of Application April 3, 1935, Serial No. 14,433

1 Claim.

The present invention relates to combustion to the arrangement of a combustion chamber 5 or cylinder to an exhaust conduit or manifold.

The usual arrangement valve with a stem slidably the valve casing and a and in cooperative relation with an opening of the.

The valve is operated by means includcylinder.

includes a valve casing, a disposed in a channel of disk secured to the stem ing a rocker arm disposed in a rocker arm box.

In general practice leaving this valve, are

the exhaust gases, after discharged directly to atmosphere or into a conduit or exhaust manifold,

the pressure in which that of the surrounding atmosphere.

is substantially equal to At times,

however, itbecomes desirable to utilize available energy in these exhaust a waste heat boiler,

or by other means.

gases in a turbine wheel, The

mostveicient utilization of this energy requires that the pressure in the exhaust manifold be appreciably higher than that of the surrounding atmosphere. Under such conditionsof increased back pressure it has been observed that the exhaust valves become overheated, the valve stems become pitted and scored and the life of the entire valve structure and other parts cooperating therewith is materially shortened. The principal cause of this difficulty is that with the constant back pressure in the exhaust manifold higher than the surrounding atmospheric pressure, hot exhaust gases flow through the clearance space between the valve stem and the surrounding channel into the rocker arm box. This ow -of gases overheats the cant from entering the valve stem, prevents lubrispace between the valve stem and the channel, and further tends to build up a pressure inside causes expelling of through any opening,

the rocker arm box which lubricant from this box however minute.

The object ofmy invention is to provide an improved construction type of combustion engi duce the injurious and arrangement of the nes above specified to reelects of exhausting into a manifold or other chamber wherein a relatively high pressure exists.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claim appended thereto in connection with In the drawing, Fig.

the accompanyingdrawing. 1 is a somewhat diagrammatic view of an internal combustion engine embodying my invention; view of a part of Fig. modifications according Fig. 2 is an enlarged detailA 1, and Figs. 3 and 4 are to my invention.

`is. controlled The arrangement shown by 'way of example in the drawing comprises al combustion engine having a casing I to which is anged a casing II of a supercharger. The supercharger in this particular instance has two stages, a rst stage I2 with an inlet or suction conduit I3 and an outlet or a discharge conduit I4. The latter fprmsan air duct to an inlet I5 of a second stage. Interposed in the air duct is a carbureter I6 in which fuel is mixed with the air discharged from the rst stage and forced into the inlet I5 of the second stage. 'I'he second stage has an outlet Il which forms an intake for an engine cylinder I8. The engine cylinder I8 is connected to an exhaust conduit or manifold I9 in which the pressure is maintained higher than that of the surrounding atmosphere. 'I'he ow of combustion gases from the engine cylinder I8 to the exhaust conduit I9 nism 20. The mechanism, as shown in Fig. 2, comprises a valve stem 2I slidably disposed in a sleeve 22 formed in a valve casing 23. The valve casing 23 in the present instance is integrally united with a portion of the cylinder I8. The

' lower end of the valve stem is secured to a valve disk 24, which latter is in cooperative relation with a seat 25 on the cylinder I8. 'I'he upper end of the valve stem 2I is engaged by a rocker arm 26 held on a fulcrum 21 and connected to a push rod 28. The valve is normally biased towards closing position and held in contact with the right-hand end of the rocker arm 26 by means of a coiled spring 29 surrounding the upper end of the valve stem 2l. The .latter and the rocker arm 26 are enclosed by a rocker arm box or casing 30. 'I'he push rod is enclosed by a tube 38. The fulcrum 21 and other movable parts of the valve mechanism are lubricated to reduce friction and wear thereof.

During operation the push rod 28 is periodically reciprocated to cause opening and closing of the valve. When the valve is opened or unseated, gases are discharged from the cylinder I8 into the exhaust conduit I9, in which as 'described above there may be a pressure higher than the surrounding atmospheric pressure. Due to this difference in pressure, the hot exhaust gases normally have a tendency to flow upward into thc small clearance existing between the valve stem 2| and the wall of the surrounding channel 22. This flow of hot gases forces out and burns away all lubricant in the clearance space, causes overby means including a valve mechaiiow of hot combustion gases with its injurious effects is reduced or eliminated in accordance with my invention by the provision of auxiliaryT means which cause an articial draft or blast along the valve stem 2|. Preferably I provide means for causing a counter-flow of iluid such as air with respect to the flow of combustion gases. In the present instance I have shown two spacedapart recesses 3| and 32 formed in the channel 22 and surrounding the valve stem 2| near its lower end. The recess 3| which is formed nearest the valve disk 24 is connected to a conduit 33 for conducting air (or other fluid) under pressure to the recess. rIhe other end of the conduit 33 is connected to a source of air or other fluid having an absolute pressure higher than the (maximum, average) absolute pressure within the exhaust manifold or chamber I9. In this particular instance it is shown connected to the air duct or outlet conduit I4 (Fig. 1) of the rst supercharger stage, the connection being made ahead of the carbureter I6 whereby air from the first stage of the supercharger is forced through the conduit 33 into the recess 3| surrounding the valve stem 2|. The portion of the channel 22 in the valve casing intermediate the recess 3| and the lower end of the channel is made slightly wider to form a clearance 34 of a width suflcient to permit a iicw of air at high velocity from the recess 3| towards the disk or lower portion of the valve stem. This counterflow of air prevents or reduces the flow of combustion gases in the opposite direction. Since the pressure established in the recess 3| is higher than that within the rocker arm box, this higher pressure might cause a iiow of air through the clearance space between the valve stem and the channel into the rocker arm box, thereby effecting ejecting of lubricant fromthis box. To prevent this I provide intermediate the iirst recess 3| and the rocker armbox a second recess 32 which is vented to atmosphere through a conduit 36. The channel portion 35 intermediate the two recess 3| and 32 has a good sliding or packing iit with the valve stem. The cross sectional area of the conduit 36 and the recess 32 ist.

appreciably larger than that of the clearance between the valve stem and the channel so that any iiuid or gases passngthrough the channel portion 35 will escape to atmosphere without creating in the recess 32 a pressure above atmosphere.

The modification of Fig. 3 comprises a valve casing 40 forming a channel 4| for a valve stem 42. A recess 43 corresponding to the recess 3| -ci' Fig. 2 is formed in the channel 4| and connected to a source 44 of high air or uid pressure. In accordance with my invention a lower portion 45 of the channel 4| intermediate the recess 43 and the end of the channel 4| is Venturi-shaped and made wide enough to permit the iiow of compressed air from the recess 43 towards the lower portion of the stem 42. The arrangement is such that the air is discharged from the recess 43 at high velocity, the velocity being gradually converted into pressure as the air leaves the lower end of theflared or Venturi-shaped channel portion 45, thereby preventing or reducing the ow of combustion gases along the stem in the opposite direction.

The modication of my invention shown in Fig. 4 comprises a valve casing 5|) having a channel 5| for accommodating a valve stem 52. Two spaced apart

annular recesses

53 and 54 surrounding the valve stem 52 are formed in the channel 5|. The recess 53 in this arrangement is connected by a conduit to a space subject to pressure equal to or less than that of the atmosphere, for instance the intake chamber of a compressor. The recess 53 is disposed near the lower end of the valve stem, that is, adjacent the valve disk, whereas the recess 54 is disposed on the side of the recess 53 remote from the valve disk.

i The recess 54 communicates by a conduit 56 with the atmosphere. The provision of the recess 56 vented to atmosphere is important whenever the other recess 53 is connected to a point of subatmospheric pressure because in this case the existence of low pressure in the recess 53 would cause the lubricant in the upper end of the valve stem and the rocker arm, not indicated, to flow downward along the valve stem. This downward flow of the lubricant is reduced byy the provision of means creating a pressure equal to the atmosphere at a point above the recess 53, in the present instance within the recess 54. During operation, exhaust gases are permitted to flow upward along the lower end of the valve stem 52 until they reach the recess 53, whence they are discharged through the conduit 55. Thus, whereas in the arrangement of Figs. l and 2 means are provided for creating an artificial flow in downwarddirection, that is, towards the valve stem, in the arrangement of Fig. 4 means are provided for creating an artificial flow upward along the valve stem, and other means are provided for reducing the iiow of air and lubricant from the upper part of the valve stem into the recess 53. Furthermore, whereas in the arrangement of Fig. 2 the lower end portion 34 ofthe channel is somewhat wider to dene an annular space with the valve stem, in the arrangement of Fig. 4 the lower end of the channel 5| has a sliding fit with the valve stem, similar to the sliding t intermediate the two

recesses

53 and 54 and corresponding to the sliding t intermediate the recesses 3| and 32 of Fig. 2.

Having described the method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means. l

What I claim as new and desire to secure by Letters Patent in the United States is:

A stumng box for an exhaust valve having a stem and a disk for controlling the ow of exhaust gases from a source to an exhaust, means having spaced upper and lower annular recesses surrounding the end of said stem near the disk, means for maintaining in the lower recess a pressure greater than that existing in such exhaust, and means for venting the upper recess to atmosphere, the channel between the lower recess and the disk forming a clearance to permit air contained in the lower recess to iiow at high velocity along the stem towards the disk.

" SAMUEL R. PUFFER.