US2404241A - Valve clearance eliminating device - Google Patents

Description

Jfily16,1946. MMMI LA 2,404,241

VALVE CLEARANCE ELIMINATING DEVICE I Filed May 14, 1945 Y INVENTOR. CkarzZeaWMacMil 7;

gr M 1 a ATTORNEY.

Patented July 16, 1946 UNITED STATES PATENT OFFICE VALVE CLEARANZ I I ZfIZ lINATING DEVICE Charles W. MacMillan, Washington, D. 0.

3 Claims.

This invention relates to clearance eliminating devices, and more particularly, but not exclusively, to such devices as may be used to a great advantage in combination with valve mechanisms or valve operating trains, such for instance as those used in internal combustion engines.

The numerous advantages which may be attained with the aid of a device adapted to maintain substantially at zero the clearancebetween the parts of a valve operating train in aninternal combustion engine, are now well appreciated in the art. It is also appreciated that additional advantages may be attained with the use of a device of this general character operated hydraulically and interposed in the valve operating train, said device being adapted to transmit the valve operating force through a column of oil, which column is automatically adjustable to take up any clearance that may occur in the valve operating train.

However, embodiment of the above principle into actual operative structures has presented many difficulties which greatly reduce and impair the usefulness and dependability of such devices. For instance, being dependent upon engine lubricating system for their oil supply, conventional devices of the above character suffer from gummy deposits, dirt, particles of metal and rust, acids and the like which are carried into and deposited in the restricted passages of the devices or between the closely machined and carefully adjusted mating surfaces of their mechanisms. In addition, such conventional devices require for their proper functioning precision machining and finishing of their mating surfaces and closely controlled clearances, which are difficult and expensive to provide and to maintain. Furthermore, the necessity of ensuring oil supply for such devices by connecting them to the lubricating system of an engine, necessitates providing long oil conduits usually drilled through walls, partitions, and other parts of the engine, which often isvery. difficult and, in general, is objectionable for a number of important reasons.

One of the objects of the present invention is to provide an improved clearance eliminating device of the hydraulic type, in which the above disadvantages are overcome and largely eliminated.

Another object of the invention is to provide an improved clearance eliminating device for valve operating trains of internal combustion engines, which device is completely sealed and self-sustained as far as its liquid supply is concerned, and

I in which relatively small quantity of specially se- 2 r lected and graded liquid, particularly adapted for its intended function, and not compromised by requirements presented to an engine lubricant, such as cheapness, is used for operating the device.

A further object of the present inventionis to provide an improved hydraulic clearance eliminating device for valve operating trains of internal combustion engines,- which device does not depend upon the engine lubricating system, for its operating liquid and, therefore, may belocated anywhere in the engine as functionally required without the necessity of leading engine oil to it through a complicated system of conduits.

A still further object of the present invention is to provide a hydraulic clearance eliminating device which may be usedin connection, with structures having no liquid supply suitable. .for operating such a device, or inconnection with structures where conducting to the devlbethe necessary supply of operating liquid isldifiicult or impractical. r

A still further object of the present invention is to provide a hydraulically operated clearance eliminating device in which precision machining and finishing operations, or closely controlled clearances are not necessary for proper function ing of the device. it

It is an added object of the present invention to provide an improved structure of the foregoing character which is simple in construction, dependable in operation, and is relatively inexpensive to manufacture.

Other objectsand advantages of the present invention will be apparent from the following description and the accompanying drawing forming a part of the present specification, in whichdrawing similar numerals refer to similar parts throughout the several views. V

In the drawing,

Figure 1 is a view showing, partly in section, a valve operating mechanism of an internal combustion engine, said mechanism including a clearance eliminating device embodying the present invention; V .I, I

Figure 2 illustrates separately on a larger scale and in longitudinal section the clearanceeliminating device of Figure 1; I

Figure 3 is a top view of the clearance eliminating device of Figures 1 and 2; c

Figure 4 is a transverse'sectionalview of the clearance eliminating device, taken in thedirection of the arrows on the section plane passing through the line 4-4 of Figure 3;

Figure 5 isa perspective view showing a modi- 7 l operably arranged in the engine structue and not of limitatio'n and it is not intended to,

limit-the invention beyond the requirements of the prior art.

In the drawing there is shown, by way of ex- 7 ample, a clearance eliminating device embodying the present invention and adapted to be used in a valve operating train or mechanism of an inter nal combustion engine.

eliminating device herein shown is not exclusive and that clearance eliminating devices embodying the present invention may be, used successfully. in combination with other mechanisms or machines where itis necessary or desirable to maintain the clearance between the contacting parts of a train of operative parts substantially at azero value.

Referring particularly to Figure 1, the-valve operating mechanism or train illustrated therein is of the type used in internal combustion engines of the overhead valve type. For the above thereof is given as is necessary for the proper understanding of'the present invention. The valve operating train comprises, generally,a cam shaft and having a cam ll of asuitable shape. The cam ll cooperates with a follower or tappet l2 operated by the cam l l and'suitably guided in the enginestructure along a straight reciprocating 'path. The .tappet l2 has an open or hollow end receiving the lower end of a rod IS, the upper end lia of saidrod being received by a socket provided on one end of the clearance eliminating device, said device being generally designated by thenumeral 20. The opposite end of the clearance eliminating device is adjustably connected to the end Ma of a rocker arm l4, said arm being hinged at the engine structure as shown at l5. The other end Mb of the rocker arm 14 bears 1 upon'the end of the valve stem of a valve It It will be understood, however, that the illustrated use of the clearance reason only as much of the detail description operatively arranged in the engine structure and adapted to seat in the valve seat ll to close and to open a port l8. A main valve spring [9 is provided,.which when unopp sed by the force .exerted by the cam l I and transmitted to the valve I 6. through the above described valve operating mechanism forces the valve 16 into its seat H to close said port l8.

It will now be understood in View'of the following, that the clearance controlling device 20' is a force transmitting member of the valve operating train, acting at times as a positive structural member thereof. It is well apreciated in the art, that considerable difficulties in operation of an internal combustion engine valve are produced by occurrences in the valve operating train of undesirable clearances, commonly called tappet clearances and usually produced by thermal contraction of the parts and of their wear, which clearances cause noisy peration of the valveoperating mechanism. On the other hand, thermal expansion of the valve operating train parts prevents proper seating of the valve and causes faulty operation of the engine due to occurrence of objectionable "valve seat clearance. The.

eration of the device is as follows: as the valve versly. Many clearance eliminating or controlling device of the present invention operates to consume "tappet clearance, as the same occurs in the valve operating mechanism, and is also effectiveto prevent occurrence of valve seat clearance, whereby quiet operation of the engine as well as proper and tight seating of its valve is ensured.

The device 20 comprises a hollow cylindrical body or cartridge 2| having a closed"- end 2la threaded at the outside and adapted to be screwed into or otherwise adjustably secured to the end 14a of the rocker arm I4, as mentioned. A nut 22 is provided to prevent undesirable rotation'of the device. Controlled rotation of the device for its approximate adjustments may be efiected with the aid of a screw driver or similar instrument engaging the device at a slot 23.

The interior of the cartridge 2| isdividedinto two part by a partition 25 screwed into or otherwise rigidly secured in the cartridge 2| to transmit valve operating force thereto. On the partition 25 and underneath thereof there is mounted a member 26 adapted to hold a quantity of liquid. The member 26 is of such a construc tion that if the quantity of the liquid therein'is increased, the size of the member 26 in its axial direction is increased. In other words, the memprising a valve seat 21, aball 28 and a ballrejtainer 29. The valve permits the flow of liquid into the memebr 26 but checks the reverse flow. The opposite end of the member 26 is closed and it carries a plug 36 guided in the open end 2lb at the cartridge body'2l by the walls thereof and provided with a socket 30a adapted to receive the ball end I3a ofthe rod I3. I i 'The member 26 is substantially rigid transimportant advantages are achieved by making the member'26 in the form of metal bellows which may be aproximately in in diameter and /2"-%" long. 'Such bellows member possesses the ability of being longitudinally expandable by the internal hydraulic pressure, but is sufficiently rigid transversely.

' On the opposite side of the partition 25 there is mounted another liquid expandable member 36 preferably of the same metal bellows construction. The member-36 is also completely enclosed and carries alquantity of liquid similarly to the member-'25. A compression coil spring 3| provided within the cartridge 2| is adapted to act on the member 36 through the washer. 32 and to maintain the liquidiwithin said member under pressure. The spring 3| is considerably weaker than the'valve operating spring l9. A restricted passage 33 is provided in the partition 25 to permit predetermined rate of flow of liquid from the bellows member 26 into the bellows member 36.

With the structure as above described, the oplifting force is applied by the cam II to the tappet I2, said force is received by the rod I3 and is transmitted by the ball end Ilia thereof to the i thereby operating to seat the ball 28 and to check is such flow. The liquid entrapped in the operating bellows member 25 being substantially uncompressible will present a substantially rigid column for transmitting of the main operating force, which in the present application of the device is the valve lifting force, to the partition 25, and consequently to the cartridge body 2| of'the device, to the rocker arm l4 and the valve l6, opening said valve against opposition of the spring it. Thus, the entire valve operating mechanism will present a rigid force-transmitting train.

Should clearance occur in the above described force-transmitting train, which in the present embodiment will normally occur in the socket 30a or at the end of the stem of the valve I6, pressure on the plug 341 will cease and hydraulic pressure within the operating bellow member 26 will be reduced to a value less than the pressure in bellows 36. Since the hydraulic pressure in the supply bellows member 36 remains substantially unchanged, due to the action of the spring 3|, substantially constant flow of liquid will immediately result from said supply bellows member 36 into the operating bellows member 26, due to unseating of ball 28. Bellows 26 thus becomes expanded, forcing the plug 30 outwardly until the clearance is consumed. Since passage 33 is relatively restricted or small as comparedwith the opening thru ball seat 2?, the relative amount of flow thru passage 33 is small and would be insufficient by itself to provide rapid expansion of bellows 23 when clearance in the valve train occurs.

Should on the other hand expansion of the valve operative train-parts cause failure of the valve It to seat properly, such condition may be only of a very short duration when the present clearance controlling device is used. The predetermined flow of the liquid through the restricted passage 33 of the partition 25, which is taking place at every valve-opening stroke of the valve mechanism, will after a relatively short period of time gradually reduce the dimension of the bellows member 26 in the force-transmitting or longitudinal direction, which will first operate to consume the valve seat clearance and thereby to ensure proper seating of the valve, and thereupon will tend to create or will create tappet clearance. rence will be immediately counteracted by the action of the spring 3| forcing the liquid into the operating bellows member 26 and expanding said member to consume such tappet clearance, as explained above.

It will now be understood in view of the foregoing that bellows members 26 and 36 hold a constant amount of operating liquid completely sealed therein. Thus, the device is self-sufficient as far as its liquid supply is concerned, and, therefore, it does not depend in any Way on the engine lubrication system for its supply of operating liquid. A high grade liquid, such, for instance,

Such a tendency or actual occuras glycerine or the like may be used in the device embodying the present invention, thereby eliminating the difficulties produced by gummy deposits. dirt, rust, particles of metal and the like which are liable to be carried into the device with engine oil.

Bellows construction of the members, eliminates close machining and finishing operations necessary where cylinder and plunger mechanisms are employed. Moreover, the device of the present invention is completely liquid-tight, with all of its vital mechanisms completely enclosed,

thereby ensuring compact and easily interchangethe clearance eliminating devices embodying the present invention. Said valve comprises a body 53 of rubber or a rubber-like material, preferably having a retaining outside member, such as shown at 4!, which may be pressed or screwed into a supporting member, suchas a member 42 corresponding to the partition 25 of the device shown in Figures 1-4. The body 40 is provided with an opening dd around whichthere is provided a plurality of tongues 43 preferabl integral with the body to and forming in their free condition a hollow figure such as a cone. It will now be understood that should pressure within the cone rise above that on the opposite side thereof, the tongues 43 will be bent and the passage for the fluid opened, permitting the flow of fluid to said opposite side. Reverse flow, however, will be immediately checked by the fluid closing the tongue and pressing them together. If desirable, the tongues may be so constructed as to permit in their closed positions a very slow flow which may serve the same purpose as the flow through the passage 33 of the device, as explained above. Construction of said tongues 43 to accomplish this purpose may be made by shortening them,

thus providing a central opening at the apex of the cone formed by said tongues when in the closed position.

I claim:

l. A clearance eliminating device including a cartridge body, a partition within said body rigid therewith, two metal bellows enclosed Within said body and mounted on both sides of said partition, respectively, one of said bellows being a forcetransmitting bellows and having one end supported on said partition, its other end being movable and adapted to receive the main operating force and to transmit the same through the mass of liquid contained therein to said partition and said body, and the other of said bellows having one end supported on said partition and the other end free and a spring acting on said other end to maintain a predetermined liquid pressure within said other bellows which pressure is less than,

ported on said partition, its other end being movable force and adapted to receive the main operating and to transmit the same through the mass of liquid contained therein to said partition and said body, and the other of said bellows having one end supported on said partition and the other end free and a spring acting on said other end to maintain a predetermined liquid pressure .7 other bellows, which pressure is less withinisaid created in said first belthan the liquid pressure lows by the main operative force acting thereon, v

and a check valve in said partition opening into said first bellows and delivering liquid thereto from said other bellows when main operating force fails to act on said first bellows, and means effecting flow at a predetermined rate from said ers being a force transmitting memberhaving one 15 the latter end supported on said partition and its other end being movable, the other container also having .one end supported on said partitioniand its other 7 end in contact with a spring tending to compress said container, the complete assembly adapted to transmit operating force of a mechanism thru a hydraulic column and control of fluid within said containers, means of said control comprising a check valve in said partition for relatively large flow of liquid in one direction between said containers and a fixed passage for relatively small flow of liquid in the opposite direction..

- CHARLES W. MACMILLAN.-

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