US2981462A - Valve comprising a plurality of individual valves - Google Patents

Description

April 25, 1961 E. NIEDERMAYER 2,981,462

VALVE COMPRISING A PLURALITY 0F INDIVIDUAL VALVES Filed July 9, 1956 3 Sheets-Sheet 1 i f fl INVENTOR .E Nbedepmay ATTORN EYS April 25,

E. NIEDERMAYER VALVE COMPRISING A PLURALITY OF INDIVIDUAL VALVES Filed July 9, 1956 3 Sheets-Sheet 2 NEYS April 25, 1961 E. NIEDERMAYER 2,981,462

VALVE COMPRISING A PLURALITY OF INDIVIDUAL VALVES Filed July 9, 1956 3 Sheets-Sheet 5 42 [Z L J 4 II I II INVENTOR E.flb'eder zzmyez BY 17/ loRNEYs Unie i Sts VALVE COMPRISING A PLURALITY OF INDIVIDUAL VALVES Egon Niedermayer, 30 Herrandgasse, Graz, Austria Filed July 9*, 1956, Ser. No. 596,476

3 Claims. ((31. 230-228) For controlling the piston compressors in many cases freely moving suction and pressure valves are used, located in the cylinder head or between the cylinder and the cylinder head of the compressor. The conventional valves of this kind are provided with circular, ring-shaped plates, made of alloy steel sheets, of a thickness between 1.2 mm. and 2.5 mm., loaded in the direction of the valve seat by a number of cylindrical spiral springs or elastic sheets. However the brutal impact of the valve plates on both sides shortens the life of these valves and requires frequent overhauling.

It is the object of the invention to eliminate these drawbacks, by improving the well-known piston compressor type whose suction and pressure valve is composed of several individual valves. With the known assemblies of this kind the individual valves are guided axially, and are loaded by a valve spring. These valves have the tendency towards sticking to their guides and will, in addition, brutally hit not only their seats but also the stops of the valve lift. In one of these modes of execution the cross-section of the holes in the Valve seat part is smaller than that of the valve opening in the open state which reduces the pressure on the valve disc at the moment of opening so that the brutal impact of the valve on its lift stop is eliminated. On the other hand, the forces moving the valve are thereby reduced which again favours the tendency of the valve of sticking to the guide, if any. Besides, the impact on the valve seat is, by this manner of design, not softened at all.

According to the invention the valve bodies are made into small circular plates, the difference between the outer diameter of the plates and the diameter of the circular inflow opening being such that, with the valve fully opened, an almost perfect equilibrium is established between the openingforce resulting from the inflow pressure and the inflow cross-section, and the force acting in the contrary direction produced by the pressure below atmospheric prevailing in the valve clearance.

The principle governing the mode of functioning of these new valves resides in the decrease of air pressure with increasing flow speed in the zone outside the inflow bore. According to Bernoulli said decrease can be calculated on the basis of the sum of the pressure head and the velocity head being constant. As soon as the small valve plate has reached a specific, small height of lift, the resulting pressure on the valve plate face exposed to the flow falls to a level so low that under certain circumstances even a force is produced directed towards the valve seat. In any case the valve plate is braked or even stopped. Which of these possibilities will materialise depends-for a given inflow pressure and for a given weight of the valve plateamong others on the inflow cross-section and on the outer diameter of the valve plate. The relation between the outer diameter of the plate and the diameter of the inflow channel must be fixed in such a manner that a sufiicient damping force is produced avoiding an excessively hard impact of the valve plate upon the stroke-arresting plate. But in determining the 2,981,462 Patented Apr. 25, 196i.

dimensional relations it is indispensable to consider also the closing motion of the valve plate as here too an excessively hard impact of the valve plate and the valve seat must be avoided, without however having to resort to a special valve spring. The ratio between the respective diameters can be so adjusted that the flow forces, acting on the small plate, make for small setting speeds in respect to the valve seat. In order to warrant the most favourable kinetic conditions both in opening and in closing, a compromise is necessary between the most favourable diameter ratio in the two directions of movement.

The design and construction according to the invention will first of all considerably increase the duration of life of the valves, considering that the reduced setting speeds will perceptibly diminish the stress to which the valve members are subjected. Consequently it is even possible to make the valve plates lighter and possibly even of plastics which offers the advantage of lesser forces due to gravity and lower cost.

If the relative diameters are correctly chosen no valve springs are required at all, which signifies a further reduction of the noxious forces due to gravity, as well as a simplification and cheapening of the valves.

According to a further feature of the invention the small plate valves may be shaped in such a manner that the contact on the seats is practically but a linear one, in consequence whereof the opening of the valve takes already place with the pressures on both sides of the plate being equal. Preferably the plates will but contact along their outer circumference, the result being that the air pressure will act on the entire surface before the plate is lifted, which bars out the acceleration of the valve motion just after the plate is lifted from its seat. Preferably this outer circumference contact of the valve plate, is obtained by the plate having, at least at its outer edge or rim, the shape of an obtuse-angled cone whose apex is located on the side opposite the seat. According to this embodiment of the invention, the cross-section of the passage of air through the valve clearance with the valve lifted, is inside but slightly smaller than outside, which means that the retardation of the air in the clearance is smaller than, in case of the valve clearance being constituted by two parallel planes. Thus the damping conditions may be influenced by the selection of the angle of the cone.

With a preferred embodiment of the invention the .small valve plates are vaulted on the side opposite the valve seat, said vault partially protruding into a suitably large bore arranged in the stroke-arresting plate, coaxially tothe inflow bore. Thus the small valve plates are assured against major lateral displacements, and are precisely centered in the raised state. It is true that in the closed state this design produces a slightly less exact centering which, however, is of no noxious influence on the function of the unit. After each lift the small plate falls down on to its seat in a practically centrical manner.

Further features of the invention relate to the design of the valve seat plate, the design and the fixation of the stroke-arresting plates, andfinally to the cooling of the valve seat plate, which is greatly facilitated by the arrangement of the individual valves. The last-rnentioned details of the invention will be explained in the following with reference to embodiments of the invention.

Fig. 1 shows the upper part of the cylinder and the cylinder head of a water-cooled compressor in a section taken along the line I-'-l of 'Fig. 2. Fig. 2 shows the suction and pressure valve, appertaining to said compressor, partly in view and partly in section taken along the line II--II of Fig. 1. Fig. 3 shows a detail of Fig. 1 on a larger scale, whilst Fig. 4 is a section taken along IVIV of Fig. 2. Fig. 5 shows one of the small valve plates on an enlarged scale. The Figs. 6 8 each show one further embodiment of the invention, the mode of presentation as to sections and scales being the same as that of the Figs. 3 and 4.

The compressor cylinder is designated by the numeral 1, the cylinder head by 2, the inlet channel of the cylinder head by 3, the outlet channel by 4. Between the cylinder 1 and the cylinder head 2 the valve seat plate 5 is clamped along its outer circumference, said plate comprising a great number of suction valves 6 and pressure valves 7 which on the side of the cylinder head are locally separated from each other by a ring-shaped sealing face 8 whilst they are connected with the inlet channel 3 and the outlet channel 4. The suction valves 6 are constituted by passage bores 9 located within the sealing face 8, whilst the pressure valves 7 are formed by passage bores 10 located outside of the said sealing face 8, both being controlled by the small valve plate 11. According to the passage direction of the medium these small valve plates are arranged below the valve seat plate 5 in the case of the suction valves and above said plate in the case of the pressure valves. On the lower side of the valve seat plate 5 a circular stroke-arresting plate 12 is provided whereas on the upper side of the pressure valves a circular stroke-arresting plate 13 is arranged. Both stroke-arresting plates are provided with the bores 14 and 1-5, coaxially arranged to the passage bores 9 and 10, respectively, the diameters of the former being smaller than those of the passage bores.

The diameters of the small valve plates 11 are considerably larger than those of the passage bores 9 and 10. On the side opposite the valve seat 16 (Fig. 5) the small valve plate 11 is provided with a vault 17, higher than the distance between the valve seat plate 5 and the stroke-arresting plates 12 and 13 respectively. Thus the vault 17 protrudes into the bores 14 and even with the small valve plates touching the seats below, so that the small valve plates can only be slightly displaced eccentrically. Even with the greatest possible lateral displacement the passage bores 9 and 10 are closed by the small valve plates 11.

The individual valves are functioning as follows: The air current, flowing out of the passage bore, will first slightly lift the small valve plate. During the air flowing out the force acting on the small plate diminishes, as a portion of the pressure is transformed into speed, so that possibly the small valve plate will come to a standstill even before the stroke-arresting plate has been reached. In practice the amount of lift available for the small valve plate will be determined in such a manner that said plate will contact the stop most softly even under the most unfavourable operating conditions of the compressor. The outer border 18 of the small valve plate 11 is conically inclined, the angle of the cone being designated by the numeral 19 (Fig. 5). As the outflow and pressure conditions on the small valve plate depend on that cone angle 19, the braking force acting on the small valve plate can be determined by a suitable selection of that angle.

In its lifted-up position the dome 17 which defines the vault of the small valve plate acts as a guide for centering said valve plate in the bore 15 of the stroke-arresting plate for which purpose the inner end of the bore 15 (or 14) presents a chamfer 20 so as to correspond to the angle of inclination of the small valve plate coming to touch it. In its lifted-up position the small valve plate is centred in said chamfer so that it will subsequently fall down again centrally on to the valve seat. In that case a certain obliquity of the small valve plate, as shown in dash lines in Fig. 5 and designated by numeral 11', is not disadvantageous.

The lower stroke-arresting plate 12 is centred in the valve plate by means of a pin 21 and an outer border 22, and is arranged within the clamping faces 29 and 30 of the valve seat plate 5. The outer pressure valve 7 is connected to the inner space of the cylinder 1 by means of cavities 38 therein. The stroke-arresting plate 12 is fixed e.g. by three screws 23 passing through the valve seat plate 5, distance rings 24 being inserted between the stroke-arresting plate 12 and the valve seat plate 5. In an analogous manner the upper strokearresting plate 13, consisting of a circular ring, is fastened to the valve seat plate 5 e.g. also by three screws 25 and the distance rings 26. In this case the screw nuts 27 are sunk into the cavities 28. It follows from the above that the valve seat plate is of simple form and consequently cheap of production. The stroke-arresting plates 12 and 13 are not hardened nor ground, but only drilled. No milling operations are required in this connexion.

For intensifying the cooling of the outer pressure valves the valve seat plate 5 is, according to the invention, provided with bores 31 running from outside in the inward direction, each bore being located between two axial passage bores 10. Each of the bores 31 is connected with a cooling water channel 32 passing through the valve seat plate 5 and connecting the water spaces 33 and 34 of the cylinder and the cylinder head. Outwardly the bores 31 are closed by plugs 35, whilst the clamping faces 29 and 30 are sealed by packings 36 and 37 inserted in-between.

According to the embodiment as per Fig. 6 the strokearresting plate 12' for the small suction-valve plates 11 is located on the inner side of the valve seat plate 5, whilst the stroke-arresting plate 13 for the small pressure valve plates (not shown) is located at the outer side of said valve seat plate. The outer diameter of the stroke-arresting plate 12 is the same as that of the valve seat plate 5, and both plates are clamped together between the cylinder 1 andthe cylinder head 2. This improves the cooling of the stroke-arresting plate over the design hereabove described thereby avoiding the formation of solid deposits, stemming from the lubricating oil and the air-borne impurities, which are often interfering with the correct functioning of the valve. The ring-shaped stroke-arresting plate 13, of an outer diameter considerably smaller, is fastened to the seat plate 5 by means of a plurality of distance rings 26 and passage screws 40. Independently of the clamping effect between cylinder and cylinder head the passage screws 40 will also hold together the valve seat plate and the stroke-arresting plate 12' so that the entire valve assembly can be easily inserted and removed, and represents a readily mountable unit. Cooling Water flows through the ducts 32 from the cylinder 1 to the cylinder head 2 thoroughly cooling on its passage both the valve seat plate 5 and the strokearresting plate 12'. For reinforcing the cooling elfect the valve seat plate 5 is provided with bag-like cooling water bores 31 located in the inward direction in parallel to the valve seat plate, and connected each with one of the ducts 32. Between the valve seat plate and the cylinder head on the one hand and the cylinder on the other hand packings 41 are provided. Likewise, between the valve seat plate 5 and the stroke-arresting plate 12', a packing 39 is located which may consist of a rubber ring. Instead of the rubber ring also a fiat metallic packing, e.g. made of aluminum, may be used.

The embodiment according to Fig. 7 differs from that of Fig. 6 solely in that in this case also the upper strokearresting plate 13' for the pressure valves extends outwardly and is clamped together with the valve seat plate 5 and the second stroke-arresting plate 12' between the cylinder 1 and the cylinder head 2. Consequently two packings 39 are required which may be made fiat from aluminum. In this case two passage screws (40, Fig. 6) are provided which however are not shown in the drawing.

The embodiment according to Fig. 8 is analogous to that of Fig. 7 with the only difierence that in this case one valve seat plate 42 is provided for the pressure valves 7 and one valve seat plate 43 for the suction valves 6,

each of these plates being integral with the stroke-arresting plate of the other valve group (42, 43). The small pressure valve plates 11 are not as with the former embodiments and with the suction valves 6 centered, by means of chamfered, coaxial passage bores, but by means of chamfering the stroke-arresting part of the plate 43 to the shape of the frustum of a cone 49. The two plates 42 and 43 are connected by a plurality of circumferentially spaced set-screws 44, and are clamped together along their outer circumference between the cylinder 1 and the cylinder head 2. Besides, they are centred with respect to each other by cylindrical projec tions 45 and 46 and sealed by means of aluminum packings 47 and 48. In this case too a cooling efiect is at- .tained by means of cooling water ducts, axially passing through the clamping face (not shown in the drawing), also bag-like holes being possibly provided as according to the Figs. 1 and 2 in both plates 42 and '43 or but in one of them.

Of course, the number of embodiments is not exhausted by the few examples given above; quite to the contrary, a great number of different types are possible without exceeding the scope of the invention.

I claim:

1. An automatic compressor valve comprising at least one valve seat plate having at least one gas flow passage extending therethrough, a stroke-limiting plate mounted in parallel relation above the seat side of said valve seat plate and formed with a plurality of openings extending therethrough from the space between the valve seat plate and the stroke-limiting plate, a thin-walled, light-weight valve plate for said gas flow passage and located between the valve seat plate and the stroke-limiting plate, said valve plate having a cup-shaped central portion and a sealing rim extending about the central portion, the outer periphery of said valve plate being the outer periphery of said rim, the rim being defined by two portions, an inner portion adjoining the central portion and an outer portion, the inner portion being spaced from the valve seat plate and the outer portion contacting said valve seat plate when said valve plate is seated on said valve seat plate, the projected area of said rim on said valve seat plate being considerably larger than the enclosed area of said gas flow passage, so that the gas pressure in the annular gap formed between the valve plate and the valve seat plate when the valve plate is unseated serves as a decelerator on the valve plate when it is opening and as an accelerator on the valve plate when it is closing, whereby the hard impact of the valve plate on the strokelimiting plate is avoided.

2. An automatic compressor valve as claimed in claim 1, wherein the central portion of said valve plate defines a portion of a spherical body, the concave surface of said valve plate facing the valve seat plate so that the convex surface of said valve plate extends toward the stroke-limiting plate, and one of said stroke-limiting plate openings is in axial alignment with said gas flow passage and forms a seat for said convex surface, thereby allowing only minor lateral displacements of said valve plate when said valve plate seats on the valve seat plate.

3. An automatic compressor valve comprising at least one valve seat plate having a plurality of gas flow passages therethrough and a plurality of shaped, thin- Walled valve plates, each valve plate being cooperable with one of said gas flow passages and having a cupshaped central portion and a sealing rim extending about the central portion, the outer periphery of said valve plate being the outer periphery of said rim, the rim being defined by two portions, an inner portion adjoining the central portion and an outer portion, the inner portion being spaced from the valve seat plate and the outer portion contacting said valve seat plate when said valve plate is seated on said valve seat plate, a stroke-limiting plate mounted in spaced parallel relation to the valve seat plate on the seat side thereof and having through openings from the space between said valve seat plate and said stroke-limiting plate as well as one abutment on the stroke-limiting plate for each valve body, said abutment being of circular cross section and arranged coaxially in relation to said gas flow passages and retaining its respective valve plate in any stroke position and centering its respective valve plate at maximum stroke in relation to the respective gas flow passage, the projected area of said rim on each valve seat plate being considerably larger than the enclosed area of its gas flow passage, so that the gas pressure in the annular gap formed between the valve plate and the valve seat plate when the valve plate is unseated serves as a decelerator on the valve plate when it is opening and as an accelerator on the valve plate when it is closing, whereby the hard impact of the valve plate on the strokelimiting plate is avoided.

References Cited in the file of this patent UNITED STATES PATENTS 195,361 Harrison Sept. 18, 1877 224,179 Guild Feb. 3, 1880 1,638,114 Dunlap et a1. Aug. 9, 1927 1,996,763 Halleck Apr. 9', 1935 2,124,323 Voss July 19, 1938 2,624,587 Watson et a1. Jan. 6, 1953 2,657,708 Kamm et al Nov. 3, 1953 2,675,758 Hughes Apr. 20, 1954 2,703,102 Neugebauer Mar. 1, 1955 2,703,583 Seligman Mar. 8, 1955 2,833,220 Robinson et a1. May 6, 1958 FOREIGN PATENTS 20,740 Great Britain July 26, 1906

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