US2019444A - Valve compensator - Google Patents

Description

Get. 29, 1935. D, CHURCH 2,019,444

VALVE COMPENSATOR Filed Feb. 5, 1950 2 Sheets-Sheet l IN VENTOR HA/Fam 0. C/yuec/i k A TTORNE Y5 H. 0., CHURCH VALVE COMPENSATOR '2 Sheets-Sheet 2 Oct. 29, 1935.

Filed Feb. 3, 1950 g 2/ H 37 a9 29 3/ 43 7 Z6 25 I i M v 3 I z 33 1 it INVENTOR HAROLD fl OWE w 4 M ATTORNEYS Patented Oct. 29, 1935 VALVE COMPENSATOR Harold D. Church, Cleveland Heights, Ohio, as-

signor to The White Motor Company, Cleveland,

Ohio, a corporation of Ohio Application February 3, 1930, Serial No. 425,436

6 Claims.

This invention relates to compensating devices, and more particularly to means for compensating for expansion and contraction in the valve mechanism of an internal combustion engine.

One object of the invention is to provide a device of the character set forth in which the variable clearance normally present between a Valve tappet and its associated valve stem or push rod is taken up by a body of liquid, the volume of which is automatically varied to compensate for expansion or contraction of the parts.

Another object is to provide a device of this type in which the relative movement between the parts due to compression and leakage of the liquid is reduced to a minimum.

A further object is to provide means to establish communication between the body of liquid in the valve and a source of supply each time the engine valve is seated.

Another object is to provide an improved arrangement for positively controlling a compensating device of this character.

Other objects relating to details of construction and economies of manufacture will appear hereinafter.

In the accompanying drawings;

Fig. l is a vertical section through a cylinder of an internal combustion engine, illustrating the application of this invention;

Fig. 2 is a horizontal section of the engine illustrated in Figure 1 taken substantially on the line 2-2 of Fig. 3 with portions of the crank case broken away to show the liquid supply ducts;

Fig. 3 is a section taken substantially on the line 3-3 of Fig. 2, the guide member being shown in elevation; and

Fig. 4 is a section taken on Fig.3.

Referring to the drawings, the numeral 0 represents the cylinder block of an internal combustion engine of the overhead valve type. Each of the engine valves co-operates with a seat l2 formed in the head I3, and is provided with a stem I4 extending upwardly through the head. Valve springs |5 surround the stem and serve to press the valve firmly against its seat. A rocker arm 56, actuated by a push rod I1, is pivotally mounted on the head and operates to depress the valve stem l4 and thereby open the valve.

A cam shaft I8 is journalled in the crankcase Hi and is driven at one-half crankshaft speed in the conventional manner. A cam is arranged on the cam shaft IS in line with each push rod I'I.

Guides 2| extend through apertures in the crankcase immediately above the cams, and are the line 4-4 of formed with flanges 22 resting upon the crankcase. The two guides for each cylinder are secured in position by means of a bolt 23 engaging the adjacent edges of the flanges 22. A cover plate 24 extends from the crankcase Hi to the head I3 and conceals and protects the push rods I! and the guides 2|.

Each guide 2| is formed with a cylindrical bore extending therethrough and having an annular enlargement 25 below the flange 22. A port 26 10 extending through the wall of the guide 2| opens into the enlargement 25 and communicates with a duct 21 in the wall of the crankcase.

Slidably mounted in each guide is a sleeve 28 having, near its lower end, an internal boss 29 15 formed with a restricted axial bore 30. A valve 3| seats on the upper surface of the boss 29 and has its stem extending through the bore 30.

A lateral bore 32 communicates with the enlargement 25 and opens below the seat of the valve 80 3|.v At its lower end, the sleeve 28 is provided with a counter-bored enlargement 33 carrying a bearing plate 34 which rides on the cam 20. The lower end of the valve stem 35 projects through the enlargement 33 and the plate 34.

Slidable within the'sleeve 28 is a tappet 36 having recesses 31 and 38 in its opposite ends. The recess 31 receives aspring 39 which surrounds the upper end of the stem of the valve 3| and bears on the valve 3| and the tappet. The recess 38 receives a member 40 which'is provided with a socket to receive the ball head 4| of the push rod The cam 20 is formed with a centrally disposed annular groove 42 which is eccentric or cam shaped with respect to the shaft l8 and which receives the projecting end 35 of the valve stem. The face of the groove 42 is arranged with its high portion represented by the arc A in Fig. 4, opposite the high portion of the cam 20, represented by the arc B, so that the valve 3| is opened when the engine valve is closed, and vice versa.

In operation, oil or other liquid under pressure is admitted to the ducts 21 through the duct 43 from any suitable source, such as the pressure lubricating system of the engine. The oil passes through the ducts 26 and 32 and is allowed to fill the space between the boss 29 and the end of the tappet 36, and also the recess 31. When the engine is operating, the cam 20 raises the sleeve 28 once in each revolution of the cam shaft. The thrust on the sleeve is transmitted to the tappet 36 through the oil confined between the sleeve and the tappet, and to the valve through the push rod l1, and the rocker arm i6. During 55 this operation, the valve 3| is held closed by the spring 39 and the pressure of the oil, the projecting end of the valve stem 35 passing through the low portion of the groove 42.

After the cam 20 has passed its high point, the valve springs l5 return the valve II to its closed position. Shortly thereafter, the high portion of the cam groove 42 engages the valve stem 35 and forces the valve 3| upwardly from its seat against the pressure of the spring 39. Oil is thereby allowed to enter or'leave the space between the sleeve 28 and the tappet 36 to compensate for any variation in length of the push rod or associated parts, and maintain a ,minimum clearance throughout the entire valve mechanism. During this cycle, the spring 39 keeps the sleeve 28 and the tappet 36 pressed apart, so that all the clear:- ance in the train appears between these two members.

It will be evident that the quantity of oil under compression when the cam 2|] opens the engine valve II is relatively small, thereby minimizing the undesirable effects arising from the relatively high compressibility of oil. In order to maintain the body of oil under compression as small as possible, the clearance between the sleeve 28 and the tappet 36 is not substantially greater than the clearance ordinarily used between the parts of a conventional valve mechanism to permit expansion. This arrangement has the additional advantage of allowing the valve to function in the normal manner even if the supply of oil should fail.

Under normal conditions, the engine is frequently started when cold. As the temperature rises the various metallic elements expand. The expansion of the valve mechanism is compensated by a gradual decrease in the quantity of oil between the sleeve 28 and the tappet 36, an increment of the oil contained between these members being expelled at each opening of the valve 3|. It is evident that the engine valve H is allowed to seat perfectly. at all times, although the oil valve 3| does not open until after the seating of the engine valve, since the extremely small amount which the valve mechanism may expand during one revolution of the cam shaft is readily absorbed by compression of the oil.

Although the invention has been described as applied to an overhead valve internal combustion engine, it will of course be understood that the compensating device may be applied to any other type of engine or machine in which it is desired to maintain a, minimum clearance between parts of variable length. It is also to be understood that the specific terminology employed is not to be construed as restrictive or limiting, and that various modifications and re-arrangements of parts may be resorted to without departing from the scope and spirit of the invention as defined in the following claims.

I claim:

1. A self-adjusting valve mechanism comprising a pair of cams, an engine valve spring-pressed to closed position, a bearing member for engaging one of said cams and receiving the thrust thereof, a tappet spaced from said bearing meme her for transmitting thrust to said valve, a spring normally maintaining said bearing member and said tappet in spaced relation, a body of liquid for transmitting thrust from said bearing member to said tappet, and a valve for said liquid con- 5 trolled by the other of said cams.

2. In an internal combustion engine, a selfadjusting valve mechanism including a cam having an eccentric groove therein, a bearing mem-, ber for engaging said cam, and a valve in said 10 bearing member having its stem positioned in said groove.

' '3. In a self-adjusting valve operating mechanism, a shaft, a cam on said shaft having a groove in the face thereof eccentric with respect to said 15 shaft, a bearing member for engaging said cam,

A and a valve in said bearing member having a stem projecting therethrough and co-operating with said groove.

4. In a mechanism for valves, an annular mem- 20 ber and movable closure forming a fluid chamber and a passage leading thereto from a fluid port associated with a source of fluid supply, a valve "gine valve, a valve stem and a cam shaft, a fixed 30 casing, a'hollow member mounted for reciprocation in the casing and having a fluid column therein, a plunger adapted to rest on the fluid column in the hollow reciprocating member between said member and the engine valve stem, a 35 slidable valve also in the hollow reciprocating member for making and breaking the fluid column, said slidable valve having a stem which protrudes from the reciprocating member, and a cam on the cam shaft having an arcuate depression 40 therein'with which the said slidable valve stem is adapted to register once every revolution of the cam, said cam being arranged to move the hollow reciprocating member within the casing;

6. In combination, a camshaft having a cam 45 thereon, a spring closed engine valve, means for receiving and transmitting the thrust of said cam to said valve including a pair of aligned members spaced apart to form a chamber therebetween, a body of liquid in such cham- 50 ber, said members being mounted to serve as a 'uniirin transmitting the thrust of said cam and to move relative to one another to adjust the length of said means, a passage formed in one of said 'members connecting said chamber with a 65 source of liquid supply, a control valve arranged to close said passage and mounted to be moved towards closed position by the pressure exerted on the body of liquid in said chamber by the thrust of said cam, a spring pressing said valve 60 towards a closed position, and a second cam on said cam shaft arranged for engagement with said control valve and designed to open said control valve at predetermined intervals in the rotation of said camshaft. 65

HAROLD D. CHURCH.

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