US2157865A - Packing device - Google Patents

Description

May 9, i939.

D. D. ROBERTSON ET AL PACKING DEi/ICE I Filed July 2, 1935 4 INVENTOR. e/zzaz .Dgezazz Patented May 9, 1939 UN'E'E STA'H'S ATENT orsi PACKING DEVICE Application July 2,

4 Claims.

Our invention is a novel valve stem packing device and method of assembling the same.

An object of our invention is to provide a packing arrangement adapted to be manufactu'red and installed very economically.

Another object of our invention is to provide a packing device of very simple character and one easily assembled.

A further object of our invention is to provide a novel tool for preparing a valve stem guide for the reception of our novel packing device.

In accordance with our invention, the guide of the valve stem has a groove in its outer face near its end and a cage having legs Whose ends are seated in said groove is used to hold a ring of packing material against the end of the valve stem guide. Such cage may be of the snap action type. The groove for holding said cage is cut before the valve and stem are in place in the bore of the guide or while the valve stem is temporarily removed, and the cutting may be done by a tool comprising a spindle-like rod, one end of which is adaptedto extend into the bore of the valve guide, a handle on the end of the rod, a cutter bar lying in a plane including said rod and pivoted thereto so that it is capable of swinging toward and away from the rod to engage its transverse cutting edge with the outside of the guide, and a nut threaded on the upper end of said rod and adapted to be turned toward the pivot of said cutter to engage the end thereof on the opposite side of its pivot from the cutting edge to force the cutting edge against the outer face of the valve stem guide. When the handle of the tool is now turned, the cutter makes a groove in the guide in a plane at right angles to its bore.

The packing ring and cage may be assembled on the valve stem guide either before or after the insertion of the valve-stem into the valvestem guide, the stem inserted in the bore of the guide therefor, and the cage manipulated so that its edge engages into thegroove on the guide to hold the packing in place.

With the above mentioned and other objects in view, our invention consists of certain features of construction and certain process steps, as will be more fully .described and particularly pointed out in the appended claims, and we have illustrated in the accompanying drawing several devices embodying our` apparatus invention and adapted to be assembled in accordance with our process invention. In the drawing:

Figure l is a sectional view of a valve seat and a valve stem guide having a tool, in accordance 1935, Serial No. 29,448

(Cl. 12S- 188) with our invention, applied to the guide to cut a groove in the outer face thereof.

Figure 2 is a view similar to Figure l illustrating a tool adapted to cut a groove having a different form from the one shown in Figure 1.

Figure 3 is a fragmentary View on an enlarged scale of an end of the valve stem guide shown in Figure l, having one form of our improved packing device applied thereto.

Figure 4 is a plan view on an enlarged scale of the cage member shown in Figure 3.

Figure 5 is a perspective View of the cage member shown in Figures 3 and 4.

Figure 6 is a sectional view of the same valve seat and valve stem guide shown in Figure i but having the tool removed and the valve and stem in operative position with two of our packn ing devices, including the cage members illustrated in Figures 4 and 5, applied to the stem guide.

Figure '7 is a plan view of a cage for use in our packing device when the groove on the guide is of the form illustrated in Figure 2, which is specifically different from the groove form shown in Figure 1.

Figure 8 is a perspective View of the cage shown in Figure 7.

Figure 9 is a sectional view of the valve seat and valve stem guide illustrated in Figure 2 but having the tool removed and the valve and stem in operative position and having a modiiied form of packing device, including the cage member illustrated in Figures 7 and 8, applied thereto.

The ordinary reciprocating valve, particularly of the type applied on combustion engines, air compressors, and like structures has a stem which extends through a guide having a bore therein for receiving the stem. The guide surface in contact with the stem of the valve may be on a sleeve forced into an aperture in the bore of the cylinder casing or may be integral with such casing, but in either case the end of such guide projects so as to have a free end against which a packing is seated to seal the joint between the guide and stem. In most cases, the packing material is pressed against the end of the guide by a cap which is held in place by a coil spring. The use of such springs is a source of difculty, requiring a longer valve stem than would otherwise be needed if the spring is on the outside of the cylinder body and complicating the assem bling and often requiring an additional spring to that used for closing the valve. Furthermore, when the packing is in the passage controlled by the valve, often the most convenient position in which to place it, the spring acting on the packing may become displaced or break and serve as a source of trouble difficult to discover; and the following is a detailed description of several embodiments of our invention whereby the foregoing advantages may be obtained and the diihoulties avoided:

Referring to the drawing, I0 is a casting of a combustion engine, an air compressor or analogous piece of apparatus, assumed to have a cylinder therein for the reception of a reciprocating piston. Casting I 0 has a valve seat I2 therein and, in axial alignment with said seat, we have shown a valve stem guide I4 held in the opening I6 in the body I6 and having a driving t therewith, although the guide I4 may be integral with body I6. The proper position of the sleeve guide I4 in body I0 is determined by a shoulder I8 on the member I4 which engages the outer face of the body I0, and the guide I4 has a bore 20 therein in alignment with the axis of the seat I2. As shown, both ends of the guide I4 project from the body I0, the outer end I4-a being clear of the body and the inner end I4--b projecting into the passage 22, which extends through the port 24 surrounded by the seat I2. In order to prepare one or both of the ends I4-a and I4--b of the body I4 for the application of packing means in accordance with our invention, we form in the outer surface or surfaces of such end or ends a groove or grooves 26--a and/or 2li-b. While we do not limit ourselves to any particular means or method for forming the grooves 26-a and 2li-b, we have devised a tool 21, shown in working position in Figure 1, especially adapted for this purpose and comprising a rod 28, having tip 3U adapted to enter the bore 28 and having a moderately close fit therewith. A collar 32 on rod 28 determines the distance which the end of tip 36 may enter the bore 20. On the rod 28 is also a block 34 having a groove 36 therein in which is pivoted a cutter 38 of bar form which lies in a plane radial to the rod 28 and has its pivot 46 in a plane transverse thereto, so that the cutting edge 42 can swing toward and away from the outer surface of the end I4B when the tool is in the position shown in Figure 1. On the opposite side of pivot 40 from the edge 42, the bar 38 has a comparatively long extension 38-a and the portion of the rod 28 outside of the valve seat I2 has a thread 44 thereon whereby a nut 46 may be turned into engagement with the portion iS-a to force the cutting edge 42 against the surface of the end Ill-b. If the rod 28 is now turned by means of the handle 48, it will be seen that the edge 42 will cut a groove 26-b in the outer surface of the guide I4, which is in a plane at right angles to the axis of bore 20. The shape of the groove 26-a or 2li-l2` will be determined by the shape of the cutting edge 42, and this is selected so that the grooves will cooperate properly with the cage to be used upon the particular installation, as will presently more fully appear.

After the groove 26--b has been cut, the tool 2`I is removed through seat I2. The valve 50 may then be put in place so as to Cooperate with the seat I2. Before placing the valve and valve-stem in operative position, however, the valve-stemguide I4 may have assembled thereon one or two packing devices in accordance with our invention. In the arrangement illustrated in Figures l, 3, and 6, the packing ring 54 of felt, asbestos, or other suitable material, is held in place against the end surface of the end portion I4-b by means of a cage 55 of the form illustrated in Figures 4 and 5. The ring 54, Figure 3, may be on either end or both ends of the guide I4, but when such ring is to be used on the inner end I4-b of guide I4, the ring 54 and cage 55 must be assembled on the stem 52 before such stem is inserted into the bore 20. As is clear from Figures 4 and 5, the cage 55 is a sheet metal stamping having a at head portion 56, a large portion of which is cut away to reduce the rigidity of the cage but which has at sectors 56-a adapted to press against and to hold the ring 54. EX- tending to one side of the plane of the head portion 56 are a plurality of legs 56-b, 56-5, which are formed by cutting out of cage 55 sections 51, 5I, to provide greater resilience. To increase the resilience also the cutouts in head 56 have radial extensions 59, 59 which lie in the same radial planes as cutouts 5'I between legs 58--b whereby adjacent sectors 56-a and adjacent legs 56--b are connected by portions 6U of relatively small cross-sectional area and adapted to twist under torsion. Legs 56-b extend generally at right angles to head 56, but the inner portions of legs 56-b nearer head 56 form portions of a conical surface which flares outwardly from the axis through the center of the head 56. The outer portions of the legs 56-5, however, bend inwardly toward said axis as indicated at 58, 58, and lie on a conical surface of slope much the same as that of grooves 2li-a and 26-2). The ends of the legs 55--b are cut off the proper length and preferably at right angles to the inwardly extending portions 58 so that portions 58 may lie in the V-shaped notches 26-a and 26-b without interference, the inner faces of portions 58 lying substantially parallel to and contacting with the outer face of the notch to hold the cage 55 in position as shown in Figures 3 and 6. Portions 58 project into the groove as shown when the cage 55 is in normal position and, in order to assemble it in this position, the legs 56-b must be sprung outwardly to permit the parts 58 to arrive at the groove '2B-a or 26-b. The cut out portions of cage 55 being so arranged, however, that the legs 56-b and sectors 58-a are connected by relatively narrow strips of metal 68 permitting the legs 56-b to be sprung in the manner described, the cage 56 can be assembled in position to hold the packing ring 54 by means of a snap action. When in assembled position, the legs 56-b are still somewhat sprung outwardly by the guide I4, so that their ends 58 press the aring surface of groove 26-a or 26-b to which they are roughly parallel and have a wedging action thereon to hold the cage firmly in place. Also the stress on legs 56-b is transmitted to sectors 56--a so that sectors 56-a are turned inwardly and press against the packing 54.

The casting l0', illustrated in Figure 2, is substantially the same as casting ID shown in Figure l, but has therein a valve guide I4 intended to receive only one of our valve stem packing devices instead of two as illustrated in Figures 1 and 6. The valve stem guide I4 of Figure 2, moreover, has a groove I4-c on its inner end which is of different form from that shown in Figure l. To cut such a groove, the tool 21 for cutting groove Il-c has a cutter portion 42 of diierent shape from the cutting edge 42. Otherwise, the tool 2'I, illustrated in Figure 2, is the same as tool 21 of Figure 1. As shown, groove Ill--c has one side in a plane at right angles to the axis of guide I4.

The cage 55 of Figures 7 and 8 has, however, a somewhat different form from the cage 55 of Figures 4 and 5 to adapt it to better cooperate with groove IIL-c. Since the groove lG-d while of V-shaped form, has one edge at right angles to the axis of the guide i6 and the other edge at an angle thereto, the cage t', instead of being of a somewhat frusto-conical shape such as cage 55, is of aA generally cylindrical form having legs provided with engaging tips 58 of inwardly tapering form complemental to the groove I 4-c. In Figure 9, We have illustrated a cage 56 arranged in position to hold a packing ring 54 in place to seal the joint between the valve stem 52 and the guide I4'. It will be understood that cage 56', when being assembled, must also be sprung or snapped into position as shown in Figure 9.

It will be seen, however, that the resiliency of the cages employed by us is useful not only in snapping them into place, but also in snapping them out of engagement with the grooves in the valve stem guide when it is desired to disassemble a given packing arrangement.

It Will be seen from the foregoing that our method or process of assembling a packing device comprises cutting a groove in the valve stem guide in a plane at right angles to the axis of the guide, and assembling a packing and resilient cage on the stem, and xing them in place against the end of the valve-stem guide by springing the cage so that its edge seats in the groove.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and We,

therefore, desire the present embodiments to be `considered in all respects as illustrative and nonrestrictive, reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

Having thus described the invention what is hereby claimed as new and desired to be secured by Letters Patent, is:

1. A struck up cage for use in retaining a packing in position in use and adapted to be assembled by a snap action, such cage having a substantially plane and partially cut out head` to decrease the rigidity of the cage, and spaced legs extending to one side of said head and connected by relatively narrow portions of metal to increase the resilience of the cage, said legs terminating in inturned gripping portions.

2. A cage for retaining packing in operative position and comprising legs extending generally at right angles to a head portion and having relatively narrow connecting portions between said legs to increase the resiliency of the Cage, said legs having inturned end portions provided with inclined surfaces adapted to exert a Wedging action on a retaining groove.

3. A struck up cage for retaining a packing in operative position and comprising a substantially plane head portion cut out to provide sectors, spaced legs fixed to said head and extending in one direction therefrom, said legs flaring outwardly from said head and then inwardly toward the axis thereof and having end portions adapted to engage one face of a V-shaped groove and exert Wedging action thereon.

4. In an internal combustion engine having a combustion chamber and a passage for oil-bearing gas, a valve controlling the movementV of said gas between the chamber and passage, a valve stem for the valve, a guide mounting the stem, said guide and stem being positioned in relatively close proximity to the combustion chamber and gas passage whereby the guide and stem are subject to high temperature and oil during operation of the engine, a packing for the stem comprising a generally annular sealing member surrounding the stem and engaging an end of the guide, and a metallic cage having a portion holding the sealing member against said end of the guide, another portion engaged with the guide, and an intermediate portion connecting the two named portions, said intermediate portion being comparatively inextensible.

DEIMAR D. ROBERTSON. GEORGE L. BRIGGS.

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