US2418674A - Valve stem construction - Google Patents

Description

P" 1947- E. c. STEINER VALVE STE CONSTRUCTION Filed Nov. 6, 1943 mvmmn EDWARD GSTE/NER Patented Apr. 8, 1947 Edward 0. Steiner, Oklahoma City, on, a

signor to Wright Aeronautical Corporation, a corporation of New York Application November 6, 1943, Serial No. 509,321

6 Claims. 01. 123-188) This invention relates to internal combustion engines and is particularly directed to the provision of means to prevent valve sticking.

In the conventional valve gear construction for an internal combustion engine springs are provided for moving the valves in a closing direction. One of the problems encountered in such a valve gear is sticking of the valve because of the accumulation of carbon deposits on the valve stem. Accordingly, it is an object of this invention to provide means associated with the valve stem to prevent valve sticking. Specifically, the invention consists in the addition of a shroud on the valve stem between the valve head and valve guide to shield the valve stem from the hot engine exhaust gases, together with the provision of a scraper in the valve guide disposed so as to clean the valve stem upon reciprocation and rotation of the stem. In addition, the invention includes a valve stem seal ring construction adjacent the upper portion of the stem for controlling oil flow between the valve stem and valve guide. With this arrangement the valve stem shroud, oil rings, and scraper all mutually contribute to prevent valve sticking.

Other objects of this invention will become apparent upon reading the annexed detail description in connection with'the drawing, in which:

flow down th valve stem from the rocker box.

In order to prevent the exhaust gases from flowing over the valve stem, an annular shroud 30 is disposed around the valve stem between the valve head and that portion of the valve: stem within the valve guide 32. The shroud 30- deflects the hot exhaust gases from contact with the valve 7 stem thereby resulting in a reduction in the oper- Fig. l is a cross-section through a rock'er box and valve gear illustrating the invention, and

Fig. 2 is an enlarged view of a portion of Fig. 1.

Referring to the drawing, a cylinder head I0 is provided with a rocker box l2 having a pivotally supported rocker arm i4 engageabie with a pushrod l6 at one end and with a valve stem 18 on a valve 20 at the other end. The pushrod I6 is operated by an engine-driven cam mechanism (not shown). The valve stem [8 is provided with an annular recess 22 for receiving the usual split valve locks 24 with which the washer 26 is engaged. A plurality of helical springs 28 are disposed between the cylinder head and washer 26 for urging the valve in a closing direction. The valve gear mechanism within the rocker box is lubricated by oil forced .up through the hollow .pushrod to the various bearing surfaces, as indicated at 29.

In connection with the exhaust valve, the hot engine exhaust gases fiow directly over the valve stem and, in addition, tend to flow up the valve stem into the rocker box. This causes excessive heating and burning of the valve stem and, in addition, carbon deposits accumulate on the valve stem to cause valve sticking. Furthermore, the engine exhaust gas flow up around the valve stem into the rocker box makes it impossible for oil to ating temperature of the valve stem l8, valve guide 32, and the valve guide boss M about the valve guide. Furthermore, the shroud 30, by shielding the valve stem from the engine exhaust gases, minimizes the accumulation of carbon on the valve stem. However, in order to remove any carbon that may deposit on the valve-stem, an annular scraper element 36 is disposed within an annular internal groove 38 formed at the lower end of the valve guide 32.

The annular scraper ring 36 is a split ring construction which is snapped into the annular groove 38 formed in the valve guide. In addition, the scraper has a depending portion. 40 and the inner face of the scraper ring is provided with a conical taper. The lower end of the scraper ring is terminated at an angle to its axis as indicated at 4! in Figure 2 whereby the scraper ring only engages th valve stem at a small point-like area. That is, the lower end of the scraper ring 35 may comprise a plane inclined to the axis of the ring and valve guide and because the interior of the scraper ring 36 is provided with a downwardly converging conical taper as viewed in Figure 2, only the lowest point on the inner edge of the inclined end 4| of the scraper ring 36 contacts the valve stem. Thus, on opposite sides of this point, the lower inner edge of the scraper ring recedes axially upwardly and, therefore, also recedes radially outwardly away from the valve stem. However, as is well known in the art, the engine valves rotate during valve operation and therefore, because of this rotation upon valve operation, the single point-like contact area of the scraper 36 clears the valve stem of any accumulated carbon deposits around its entire periphery tor a length determined by the extent of the reciprocation of the valve in a manner similar to the operation of a cutting tool. Furthermore, since the scraper only engages the valve stem at one point,lt leaves the valve as free as possible for its inherent rotation in the valve guide.

With the annular shroud 30 disposed about the valve stem, the exhaust gases flowing over the shroud tend to create a low pressure area between the shroud and the valve guide. This low presstem and valve guide, a pair of contracting split oil rings 42 are disposed about the upper portion of the valve stem in the rocker box. An annular spacer ring 44 is disposed betweenthe oil seal rings and a cup-shaped retainer member 46 which is threadedly secured to the valve guide, as illustrated. The interior of the cup-shaped retainer member is vented by a plurality of holes 48. The internal face of the oil rings 42 is cut back at a sharp angle, as indicated at all, so as to leave only a narrow band in contact with the valve stem. This construction prevents jamming of the oil rings by accumulation of carbon on the stem expanding the rings.

With the aforementioned construction, the shroud and scraper combine to maintain the valve stem substantially free of carbon deposits, and the oil rings, together with the shroud, provide for proper lubrication of the valve stem within the valve guide. That is, the provision of the valve stem oil rings, shroud, and scraper as disclosed, all mutually contribute toward the prevention of valve sticking.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modifications and changes.

I claim as my invention: 1. In combination, a valve guide structure hav- 7 ing a bore therethrough, a valve having a stem mounted for reciprocation within said valve guide bore, and means supported by said valve guide structure in scraping engagement with said stem for removing deposits therefrom upon reciprocation of said valve, said means having a sin gie point engagement with said stem and being otherwise free of said stem.

2. In combination, an internal combustion engine exhaust valve having valve stem and valve head portions, a valve guide structure having a bore therethrough within which said stem portion is mounted for reciprocation and rotation, an annular shroud concentrically carried by thevalve about the valve stem portion and extending from the valve head portion toward the valve guide structure for deflecting the engine exhaust gases away from the valve stem portion and valve guide structure, and a scraper member supported by and at the valve head end of said valve guide structure in single point engagement withthe valve stem portion. l

3. In combination with the exhaust valve of an internal combustion engine, a valve guide structure having a valve guide bore therethrough, said valve having a stem mounted for reciprocation and rotation within said valve guide bore and having a valve head on said valve stem. an annular shroud concentrically carried by the valve about the valve stem and extending from the valve head toward the valve guide structure for deflecting the engine exhaust gases away from the valve stem and valve guide structurepsnd a scrapen membersupported by said valve guide structure adjacent its valve head end and engaging the valve stem portion, said scraper member 7 having a single point engagement with said valve stem portion whereby the scraper removes ensine, exhaust deposits from the valve stem upon recip-' rocation and rotation of said valve.

4- In combination with the cylinder head ofan internal combustion engine. a valve gear rocker box carried thereby. a valve guide structure carried by said head and having a valve guide bore communicating at one end with said rocker box. an engine exhaust valve having a stem portion mounted for reciprocation within said bore with 1 one end extending therethrough into said rocker box, a valve head at the: other end of said stem portion. said valve having an annular shroud structure concentrically disposed about the valve stem and extending from the valve head toward the valve guide structure for deflecting the ensine exhaust gases away from the valve stem and I valve guide structure, oil seal ring means mounted for cooperation with said one end of said valve stem portion for controlling the flow of oil be-- tween said valve stem and valve snide, and an annular scraper member supported by said valve uide structure adjacent its valve head end for said stem passes, and a valve stem scraping point at the small diameter end of said conical surface. said scraping point being formed by axially cutting back said member on both sides of said point.

6, In combination, a valve-guide structure having a bore therethrough, a valve having a stem mounted for reciprocation within said bore, and means supported by said valve guide structure in scraping engagement with said stem for removing deposits therefrom upon reciprocation of said valve, said means being free of the valve stem except fora contact area engaging said valve stem and of small angularextent about said valve stem.

EDWARD C. STliilNm.

REFERENCES CITED The following references are of record in the file of this patent:

British 3, 1937

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