US3044686A - Rotary compressor - Google Patents

Description

July 17, 1962 v. s. MAKAROFF ETAL 3,044,686

ROTARY COMPRESSOR 3 Sheets-Sheet 1 Filed Feb. 25, 1958 @MTW July 17, 1962 v. s. MAKAROFF ETAL 3,044,686

' ROTARY COMPRESSOR Filed Feb. 25, 1958 3 SheebS-Sheet 2 l 76 @il-nii 1 INVENTORS vfw/m s. msx nnen. Al EXIS E. 7Bn/(50M HTTOPNE Q mmm v. s. MAKAROFF ETAL 3,044,686

July 17, 1962 ROTARY COMPRESSOR 5 Sheets-Sheet 3 INVENTORS Filed Feb. 25, 1958 United States Patent O 3,ti44,686 RUTARY CMPRESSR Vadim S. Makaroif, 1 E. 64th St., New York 21, NX., and Alexis E. Jackson, Norwalk, Conn. Mrs. llldtllaine Lefebvre, 17 E. 64th St., New York 21,

Filed Feb. 25, 1958, Ser. No. 717,434 '7 Claims. (Cl. 2250-147) This invention relates to compressors and, more particularly, to valving methods and structure o-f rotary piston compressors.

The general principle of the rotary compressor here described is Well known. It is mentioned, for instance, in Patents No. 1,623,315 and 2,643,817.

rIlle compressor consists of a rotary piston actuated by a crankshaft, a piston rod rigidly connected to the piston and reciprocating in an oscillating guide.

The combination of a rotary motion of the crank, oscillating motion of the piston rod guide and a reciprocating motion of the rod results in the gyration of a rotary piston within a cylinder in a way that air is constantly drawn on one side of the piston and compressed on the other.

The oil being led to the system at a pressure lubricates, cools and seals the clearances in the compressor.

Compressors of this type are now being used as slow rotating vacuum pumps or small low pressure gas compressors for household refrigerators where space rather than etlciency guides the design.

In order to design a rotary compressor to operate at high pressure and eciency, the basic difference in the performance of a reciprocating piston compressor and a rotary compressor must be kept in mind. lIn the former, the reciprocating piston compressor, the air compressed in the dead space of valve seats as well as leak-back of the valves between the time the top of the stroke is reached and closing of the valves, return the energy to the system f on the downward (intake) stroke. On the other hand, air compressed in the valve seats or a leak-back in the rotary compressor is a complete Waste. The expansion of such air goes only to decrease its volumetric eiiiciency. The work of the expansion is never recovered.

To eliminate the back leaks of the valves in a rotary compressor, poppet Valves are placed in the cylinder end plates and so positioned that towards the end of the exhaust stroke, the outlet port opening is either covered or overlapped by the side of the piston. In this manner, the outlet port is closed during a part-the last part of the compression. In other words, the outlet port is closed at irst, not by the valve but by the side of the piston.

The amount of overlap, the lift of the valve and the force of the spring are chosen to enable the valve to be closed at or before the time the piston will start uncovering the outlet port. The overlap should be limited by size not to permit the lower edge of the outlet port opening to extend below the lower edge of the piston.

To relieve the oil and air at the piston rod after the outlet port is covered by the piston, a feed-back of such oil to the valve takes place through a channel in the piston. If it is found desirable to have a large overlap, such channel is so positioned as to be disconnected from the outlet port at a desired time.

All the patents that incorporate valves placed on the cylinder coverings have one thing in common. seats are set either on the outer side of the cylinder cover or somewherer around the middle of the cover. In this manner a sizable dead space is formed between the edge of the outlet port opening and the valve.

To reduce the dead space of the outlet port opening to a minimum, poppet valves are used. The seat is shaped at the inner side of the end plate and the valve is spheri- Fice cally shaped in order to reduce the dead space to a minimum.

Where eiiciency is of primary importance, a valve with a seat close to the outer side of the cylinder cover or even half-way between the inner andthe outer surface of the cylinder cover will not do. In other words, to reduce the dead space only valves with a seat at the inner side of the cylinder can be used.

The overlap of valves by the side of a piston allows a lift of the valve of 1A as against .035 which is standard practice at 1740 r.p.m. on valves of a reciprocating compressor.

High speeds are of the utmost importance in operating a vacuum pump based on the above rotary principle. In a slow moving vacuum pump, the oil in the system has time to give up the air it carries back to the vacuum. If the speed of the vacuum pump is high enough the oil will not have the time to discharge the air. Therefore, everything said above about the compressor applies equally to the vacuum pump.

It is, therefore, an object of the present invention to provide la rotary piston type compressor which is simple in construction, eicient in operation, and which will substantially reduce the volume of air compressed in the valve seats and the leakback so as to overcome the aforementioned loss of power.

Another object of the present invention is to provide a rotary compressor which has automatic valves located on the cylinder covering or end plates in such a manner that the valve seats are shaped at the inner sides of the cover or end plates.

A further object of the present invention is to provide a rotary piston type compressor of the type described, in which the loutlet port is positively closed by the side of the rotary piston toward the end of the compression portion of the stroke for a sufficient period of time to enable the valve head to fully seat itself before the time the valve opening is uncovered by the piston.

Still a further object of thepresent invention is to provide a rotary piston compressor in which the piston has self-contained and properly positioned channels to relieve the oil and air pressure adjacent to the piston rod or tail blade of the piston after the outlet valve opening is covered by the piston.

All of the foregoing and still further objects and advantages of this invention will become apparent from a study of the following specification, taken in `connection with the accompanying drawing, wherein:

FIG. 1 is a longitudinal lcross-sectional View of a rotary piston tank compressor made in accordance with the present invention, showing the piston in a position prior to the completion of the compression portion of its stroke.

FIG. Z Ais a transverse cross-sectional view taken along line 2--2 of FIG. l.

FIG. 3 is a transverse cross-sectional view taken along line 3 3 of FIG. l. Y

FIG. 4 is a transverse cross-sectional View taken'along line 4 4 of FIG. 2. Y

FIG. 5 is Ia side elevational view of FIG. 4.

FIG. 6 is an enlarged fragmentary view showing certain parts of the 'apparatus shown in FIG. l, -in an adjusted position, wherein thev piston is `in substantially overlapping relationship with the outlet portion. f

FIG. 7 is a view similar to FIG. 6, showing the pis ton iat the end ofthe compression portion of its stroke.v

FIG. 8 is a view similar to FIG. 6, showing ya modified Y.

arrangement of the relief channel.

FIG. 9 is a View similar to FIG. 8, showing the piston at the top of its compression stroke.

FIG. l0 is `a fragment-ary cross-sectional view taken along l-ine 8 8 of FIG. 7.

p FIG. 1.1 is a side elevational view of FIG. 10.

FIG. 12 is a view similar to FIG. l, showing a modied form of piston construction, the arrangement and construction of valves being the same `as described with respect to FIG. 1.

Referring now to the drawing, and'more particularly to FIGS. l to 4 thereof, a rotary piston type compressor made in accordance with the present invention, is shown to include a casing 12 that delines a circular cylinder 13. The upper portion of the casing 12 is provided with a socket 18 that communicates with the cylinder 13 for receiving a segmental circular plate 15 having a diametrical channel 16 for slidably receiving the tail blade 17 of the rotary piston 26.

A low pressure inlet port 22 is disposed at one side of the socket 1S in communication with the cylinder chamber 13, while a high pressure outlet port 24 is disposed on the opposite side. The uppermost portion of the casing 12 is also provided with an enlarged recess 26 for accommodating the limited movements of the adjacent end of the tail blade 17, which result from the eccentric gyrations of the piston 20.

The casing is constructed from a pair of end plates 29 having a cylinder 13 clamped therebetween. The end plates 29 have recesses 34 for receiving circular hubs 33 that are rotatably supported on bearings 35 secured therewithin. Lubricating oil ports 32 also communicate with these recesses 34 to supply a suliicient amount of lubricating oil to the moving parts. A split crank bearing 37 is pressed into the piston 20. Thus, in response to rotation of the main shaft 36 by any suitable means connected to `the main shaft through the coupling 39, the piston will gyrate eccentrically within the cylinder cham ber within a plane parallel to the sides defining such chamber. This causes the piston to gyrate eccentrically in a clockwise direction as viewed in the drawing, such that it moves forwardly past the outlet port following its movement past the inlet port.

As is more clearly shown in FIGS. 3 and 4 of the drawing, each one of the end plates 29 is provided with an outlet port 24, through which the compressed gas is forced, and which is radially spaced inwardly from the outer circumference of the chamber 13. Each such port denes an outwardly `facing valve seat 42, which is spaced from the inner face of the end plate only by a minimum thickness of the end plate material, and communicates with an enlarged bore 41. A segmental spherical valve head 43 is releasably supported upon each such valve seat 42 and urged toward closing engagement therewith by means of a compression spring 50 carried within a hollow boss 46 which is received within a sleeve 45 integral with the valve head 43. This spring S0 acts between the valve head 43 and the perforated plate 47 which is integral with the boss 46. The plate 47 has a plurality of perforaons 49 which permit compressed gas to ilow outwardly into a discharge duct 52 from t'ne compression chamber through the outlet port 24 in response to movement of the valve head 43 to the open position. Since the valve seat 42 is immediately adjacent to the outlet port 24 in each respective end plate 29, the dead space 44 remaining between the valve head 43 and the plane of the inner surface of the end plate is held to a minimum. This space is further reduced by the fact that the valve head 43 is of segmental spherical shape so that the innermost extremity thereof extends to the plane of the inside surface of such end plate.

The discharge ducts 52 are defined by plates 57 that are secured to the casing by means of bolts 58. These ducts 52 communicate with a common passageway 53 which directs the compressed gases outwardly through the high pressure line 5S.

For purposes hereinafter described, the peripheral portion of the piston a illustrated in FIGS. 6 and 7, adjacent to the trailing side of the tail blade 17 and on at least one face thereof, is provided with a channel or duct 60a. Each such duct 60a extends inwardly and CAB rearwardly with respect to the direction of movement of the piston `and serves to remove compressed gas and oil from the dead space 61 defined between the adjacent peripheral portions of the piston, the cylinder chamber, and the tail blade 17, and the dead space 62 adjacent to the segmental circular plate 15, after the piston 20a moves into closing engagement with the outlet port and until it passes the top of its compression stroke for up to 30 degrees of rotation therebeyond. Thus, while the gas and oil so conined would ordinarily be further compressed at a sacrifice to the eiciency of the unit, such gases and oil are permitted to escape into the peripheral end of the channel 68a and out of the inner end of that channel which remains in communication with the outlet port 24 for a portion of that part of the cycle in which the piston overlies and covers the outlet port 24 until the piston reaches the position shown in FIG. 7. During the remaining portion of that part of the cycle and until the outlet port 24 is uncovered by the piston, the valve spring 50 is allowed to recover to permit the valve head 49 to move into closing engagement with the valve seat 42. This complete exhaust of the gases and oil, and the complete momentary seating of the valve virtually eliminates knocking that might otherwise occur, and reduces wear.

In the embodiment illustrated in FIGS. 8 and 9' of the drawing, a channel 6b is provided on at least one face of the piston in a manner similar to that previously described in connection with the channel 60a illustrated in FIGS. 6 and 7. In FIGS. 8 and 9, however, the duct extends inwardly and forwardly with respect to the direction of rotation of the piston, whereby communication between the interior of the cylinder and the outlet port 24 through the channel 601) commences at substantially the same point as the channel 60a but terminates just as the piston reaches the top of its stroke rather than after it passes the top of the stroke. This has the effect of reducing the proportionate period of time for such communication while increasing the period of time in which the spring is permitted to recover for the remaining part of that portion of the cycle in which the piston covers the outlet port.

An alternative arrangement is shown in FIGS. l0 and 1l, in which both channels 60a, b are combined to provide a composite channel 60e upon either or both sides of the piston 20 for the purpose of providing the effects of both of the aforementioned arrangements illustrated in FIGS. 6 to 9.

In each arrangement, however, each port 24 is spaced radially inwardly from the circumference of the cylinder chamber to allow the piston to close the port for a longer period of time during its rotation than would be the case if it were at the circumference and relatively tangent to the piston.

Referring now to FIG. 12 of the drawing, a slightly modified form of piston construction 70 is shown wherein the tail blade or piston rod 72 is guided within the bore 7S of the casing 12 for reciprocating longitudinal movement. The inner end of this tail blade 72 is provided with an arcuate head 73 which is received within a similarly shaped arcuate socket 75 in the peripheral portion of this piston 76. In this construction, the piston 76 will follow substantially the same path and movements of the aforementioned rotary piston 20, such gyrating eccentric motion being permitted by the spherical head 73 and socket 75 rather than by the rotatably mounted segmental circular plate 15 and socket 18 in the aforementioned embodiment. Except for this distinction, the construction and operation of both embodiments are the same.

It will thus be recognized that a rotary compressor has been provided which will enable the oil and air pressure adjacent to the tail blade to be relieved after the valve opening has been covered by the piston so as to enable a feed back of such oil to the valve to take place through While this invention has been described with particular reference to the construction shown in the drawing, it is to be understood that such is not to be construed as imparting limitations upon the invention, which is best defined by the claims appended hereto.

Having thus described our invention, whatwe claim as new and desire to secure by Letters Patent, is:

11. In a rotary compressor wherein liquid is used as a sealing and lubricating medium, the combination of a casing having inside wall surfaces including a hollow cylinder and end plates dening a main cylindrical chamber, an eccentrically gyrating piston in said main chamber, a low pressure inlet port communicating with the interior of said chamber, a high pressure port extending through an end plate and communicating with the interior of said chamber, said outlet port having its mouth located radially inwardly from the peripheral wall of the chamber whereby the piston will overlap that par-t of the perimetral edge of the port mouth which is reached last by the piston in its travel, said high pressure outlet port having a counterbore and dening an outwardly facing valve seat located at the inner face of the end plate, a poppet valve head supported upon said casing in normally closed engagement with said valve seat, and said valve head being of segmental spherical configuration and the inner extremity of said valve head extending into proximity with the plane of saidrespective chamber-defining side wall and in said normally closed position substantially filling said outlet port between said seat and said inside wall of said chamber, said piston having an integral tail blade, the upper portion of the casing being provided with a `socket that communicates with the cylinder, a segmental circular plate oscillatably received in said socket, said circular plate having a diametrical channel, the tail blade of said piston being reciprocably operable in said diametrical channel.

2. A rotary compressor a-s set forth in claim 1 further characterized by having an outlet channel on the side of said piston adjacent to said outlet port, said channel maintaining open communication between said outlet port and the space bounded by the tail blade, the Walls of the chamber, the line of tangency between the piston and the cylinder, and the curved wall of the piston between the line of tangency and the tail blade, as the piston covers said outlet port and until the piston reaches the end of the icompression stroke.

3. A rotary compressor comprising, in combination, a casing having side and peripheral walls defining a cylindrical chamber, a low pressure inlet port in a side wall communicating with the interior of said chamber, a high pressure outlet port in the other of said side walls communicating with the interior of said chamber and having a valve seat located at the inner face thereof, a poppet valve yieldingly seated on said valve seat, a piston within said chamber, said piston having a tail blade, means operatively associated with said piston for eccentrically gyrating said piston in a plane parallel to and in sliding engagement with said side Walls, said piston moving forwardly past said inlet port subsequent to passing over vsaid outlet port, and outlet channels on the side of said piston adjacent to said outlet port, said channels simultaneously communicating with said outlet port and the space bounded by said chamber, piston, and tail blade as said piston covers said outlet port and until the piston reaches the end of the compression stroke. f

4. A rotary compressor 'as set forth in claim 3, wherein said outlet channel comprises a groove in said side of said piston extending inwardly from the'peripheral surface thereof and inclined rearwardly with respect to the direction of movement of said piston.

5. A rotary compressor as set forth in claim 3, wherein said outlet channel further comprises a first groove in said side of said piston extending inwardly from said peripheral surface thereof and inclined forwardly with respect to the direction of movement of said piston.

6. A rotary compressor as set forth in claim 5, wherein said outlet channel further comprises a second groove in said side of said piston extending inwardly from said peripheral surface thereof and inclined rearwardly with respect to the direction of movement of said piston, and said first and second grooves intersect each other.

7. A rotary compressor as set forth in claim 4, wherein said outlet port has a counterbore which defines a valve seat at substantially the inner Vface of the side wall having `said outlet port, and said poppet valve comprises a valve head within said outlet port movable outwardly. of said chamber from closing engagement with said valve seat toward an open position, spring means normally urging ysaid valve head toward a closed position relative to said outlet port, and said valve head being of segmental spherical configuration and the inner extremity of said valve head extending into proximity with the plane of said respective chamber-defining side wall and in said closed position substantially filling the space between said valve 'seat and said respective side wall of said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,491,813 Milne Apr. 29, 1924 1,664,733 Braun Apr. 3, 1928 1,681,583 Guttner Aug. 21, 1928 `1,922,423 Ericson Aug. 15, 1933 2,195,835 Bilderbeck i Apr. 2, 1940 2,457,221 Girard Dec. 28, 19'48 2,643,817 Makaroif et al June 30, 1953 FOREIGN PATENTS 358,464 Great Britain Apr. 5, 1930 410,147 Germany Feb. 18, 1925 471,645 France of 1914 471,873 Germany Feb. 2.6, 1929 687,416 Germany Ian. 29, 1940 717,611 Germany Feb. 18, 1942

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