US2839008A

US2839008A - Pump or motor

Info

Publication number: US2839008A
Application number: US523221A
Authority: US
Inventors: Stansfield Hamill; Edge James
Original assignee: CARNEY STANSFIELD CO
Current assignee: CARNEY STANSFIELD CO; CARNEY-STANSFIELD Co
Priority date: 1955-07-20
Filing date: 1955-07-20
Publication date: 1958-06-17
Anticipated expiration: 1975-06-17

Description

June 17, 1958 sTANSFlELD T L 2,839,008

PUMP 0R MOTOR 2 Sheets-Sheet 1 Filed July 20, 1955 June 17, 1958 u H. STANSFIELD ETAL PUMP 0R MOTOR 2 Sheets-Sheet 2 Filed July 20, 1955 m m m CaM 7913M, WW4 (0% United States Patent PUMP OR MOTOR The present invention relates generally to reciprocat ing piston pumps, motors, and compressors.

It is an object of this invention to provide a reciproeating piston pump, motor or compressor in which the components are disposed in a balanced relationship so as to eliminate axial thrust within the unit, and thereby eliminate the necessity of using thrust bearings and seals therein.

P 'Another object of this invention is to provide, in such a pump, motor or compressor, improved pistons which are suitable for use with a barrel cam and which are constructed so as to nest around the barrel cam and thereby be prevented from turning in the cylinder bores.

A further object of this invention is to provide a pump,

motor or compressor of the type set forth above and in which the pistons are double acting to provide a continuous flow of fluid for a substantially smooth uninterrupted operation. Other objects'and advantages will become apparent to those skilled inthe art as the following detailed descrip. tion proceeds, taken in connection with the accompanying drawings wherein: t

Figure 1 is a perspective view with parts cutaway of apump or motor embodying the present invention.

Fig. 2 is a diametric cross-sectional view of the illustrative embodiment shown in Fig. 1.

:"Fig. 3 is a sectional view taken in the plane of line 3--3 of Fig. 2.

Fig. 4 is a sectional view taken in the plane of line 4 -4 of Fig. 2.

Fig.5 is a perspective view with parts cut away of the present invention in. modified form for use as' a compressor. I

.Fig. 6 is a partialcross-sectionalview of the compressor shown in Fig;

Fig. 7 isa view taken in the plane of line 7-7 of Fig. 6. i

pFig. 8 is a partial cross-sectional view of a modified form of a compressor embodying the present invention. .Fig. 9 is a sectional view taken in the plane of line 99 of Fig. 8. gWhfle the invention is susceptible of various modifications and alternative constructions, certain preferred em bodiments have been shown in the drawings and will be described below in detail, It should be understood, however, thatthere-is no intention to limit the invention to the specificrforms disclosed, but, on the contrary, the intention-is to cover all modifications and alternative constructions fallingwithin the spirit and scope of the invention as expressed in the appended claims.

;In accordance with the present invention, as illustrated in Fig. 1, there is provided a fluidpressure pump or motor device 20 which includes a pair of

cylinder barrels

21 and 22 spaced axially apart on a rotatable shaft 24 and having a; plurality of circumferentially spaced, axially disposed cylinder bores, 25 and-26, respectively, thereil y, The cylinder bores in one barrel are axially aligned with the cylinder bores in the other. barrel so there shown in a preferred balanced arrangement.

that a single piston is received in a pair of aligned bores.- An even number of these cylinder pairs are disposed in a circumferentially spaced relationship around the shaft. This disposition of the pistons and cylinders results in opposing forces of equal magnitude on diametrically opposite pistons, sothat the axial forces are balanced thereby eliminating an axial thrust on the shaft. The pistons 28 reciprocate in the corresponding cylinder bore pairs and are operatively connected to a cam 29 which is secured to the shaft 24 intermediate the barrels. The cylinder bores in which the pistons reciprocate are interconnected through a suitable porting arangement so as to provide a continuous flow of fluid when the device is acting as a pump or a smooth, non-pulsating motor action when the device is operating as a fluid pressure actuated motor.

In the following description, the device 20 illustrating the present invention will be considered to be a pump in which the shaft 24 is rotated by a suitable power means in order to reciprocate the pistons 28 in the

cylinders

25 and 26 and thereby create a pumping action. It will be appreciated, however, that upon the application of pressure fluid to the device 20, the pistons will be reciprocated in the cylinders and will rotate the shaft to drive the device as a motor.

Referring now to Fig. 2, the piston and cylinders are The

cylinder bores

25 and 26 are circumferentially positioned radially equi-distant from the axis of the

barrels

21 and 22, and when the barrels are properly oriented relative to each other, the corresponding cylinder bores in each barrel are disposed directly opposite each other. A plurality of piston rods 28, corresponding in number to the bores in a single barrel, are slidably positioned in the

respective bores

25 and 26 of the two spaced apart, confronting

barrels

21 and 22. Both ends of each piston rod are utilized as pistons, the piston surfaces and corresponding bore surf-aces being machined smooth and to a clearance sufficient to prevent leakage of fluid between the piston and the cylinder bore wall.

End plates

31 and 32 are provided which, when mounted adjacent the outer ends of these barrels cover the cylinder bore openings in these ends. An axial opening is provided in one of the plates 31 to rotatablyreceive the shaft 24. The cylinder barrels and plates are assembled with the barrels in a spaced-apart relationship with a cylindrical housing 34, disposed intermediate the barrels to form an enclosed chamber 35 therebetween. A port 36, including a suitable pressure fluid fitting, is provided in the center of the plate 32, not having the axial shaft opening, while a port 38, also including a pressure fluid fitting, is similarly provided in the cylindrical wall 34.

The distributing valve arrangement for the pump has been constructed so as to utilize the rotary shaft as the moving part thereof for connecting the cylinders alter-. nately to the inlet port duringthe intake or suction stroke of the piston and to the discharge port during the pressing or discharge stroke of the piston. In order to form such a valve, sleeves 41 and 42 are pressed into the axial bores ofthe

cylinder barrels

21 and 22 respectively, and act as journals for the shaft'24 which passes axially through the barrels. A plurality of channels are cut in the external surface of the sleeves so that when the sleeves are inserted in the axial bore of the cylinder barrels, passages are formed between the cylinder barrel and the sleeve for the transmission of pressure fluid. .As shown in Fig. 3, outer channels 44 in the sleeves 41 and 42 communicate with radial grooves 45 in the end plates. These: radial grooves ,45 communicate in turn with the outer ends of

cylinder bores

25 and 26.. Similarly, as.

. shown in Fig; 4, inner channels 46 in the sleeves 41 and- 42 communicate with radial grooves 48 in the inner end surface of the

cylinder barrels

21 and 22. The grooves 48 communicate in turn with the chamber 35 which is formed between the cylinder barrels by the housing 34.

The shaft 24, which forms the rotary portion of the control valve, is provided with an axial bore 50 and two spaced segmental cut out portions 51 and 52, displaced circumferentially 180 from each other on the shaft periphery, and communicating with this bore. The bore 50 terminates at the inner end of shaft 24, which inner end projects into a recessed portion 54 of plate 32. Port 36 provides an opening into the recess 48. Spaced apart segmental cutouts 61 and 62 on the periphery of the shaft 24 are positioned intermediate andat a circumferential displacement of 180 from the respective ad jacent cutout portions 51 and 52, each pair of the cutouts being located on the shaft in a position approximating that of a surrounding cylinder barrel. The intermediate cutouts are located so as to provide a communication between the inner and

outer channels

46 and 44 in the sleeves, radial ports through the sleeves communieating with each channel being provided. Thus, as the shaft 24 rotates, the cylinder bores 25 and 26 alternately communicate, through the outer sleeve channels 45 and the grooves 44 in the end plates, with the port 36 in the end plate 32 by means of the segmental cutout portions 51 and S2 and bore 50 in the shaft, and with the port 38 in the housing 34 by means of the intermediate segmental cutout portions 61 and 62 in shaft 24 which lead through the inner sleeve channels 46 and the barrel grooves 48 into the chamber 35 formed by the housing 34.

The segmental cutout portions 51, 52, 61 and 62 of the shaft 24 are of sufiicient size to communicate through the respective passages in the sleeves, with a cylinder bore during a substantial part of the inward or outward stroke of the piston reciprocating therein.

Reciprocation of the rods and pistons in the cylinder bores is accomplished by means of the barrel cam 29 having a cam track 64 on its peripheral surface. Follower pins 65 depend from piston rods 28 intermediate the ends thereof and are guided by the cam track 6 4 into which they are directed. The cam 29 is positioned between the

cylinder barrels

21 and 22 and is spaced therefrom by means of washers or gaskets 66. The position of the cam track 64 on the cam must be correlated relative to the cutout portions 51, 52, 61 and 62 so as to permit the shaft to act as a rotating valve.

In other words, when the piston has reached the end of its suction stroke, and is starting its discharge stroke, the particular cutout portions on the shaft are positioned so that the cylinder communicates with the discharge port of the pump. This action may be more readily understood by reference to Fig. 1 of the drawings, and observing the pump action at the end including the suction or inlet port 36. The port 36 in the end plate 32 will be assumed to be the suction port for purposes of the present description, although it will appear that the operation may be reversed to use this port as the discharge port by merely reversing the direction of rotation of the shaft. When the pump shaft 24 is rotating in the direction of the arrow, shown near the end of the shaft 24, one of the pistons 28, which is labeled A in the particular instantaneous position shown, will be in the early stages of its suction stroke. As the shaft rotates further, the piston A will move away from the end plate to create a suction in the cylinder bore26. The outer segmental cutout portion 52 of the shaft 24 is then in communication with both the inlet port 36 and the cylinder bore in which the piston A is creating a suction. Fluid which is supplied to the pump inlet port 36 will then be drawn, through this cutout portion, into the cylinder .bore by the piston A.

Simultaneously with this suction or intake action of piston A, another piston, such as the one labeled B, will be exhausting fluid which it has-previously drawn 4 into its cylinder bore. This fluid is exhausted through the inner segmental cutout portion 62 of the shaft, which is adjacent the outer segmental cutout portion, and into the chamber between the

cylinder barrels

21 and 22. From this chamber the fluid is exhausted through the discharge port 38 in the housing 34 (Fig. 2).

The cam track, in this particular embodiment, is designed to reciprocate the piston through one complete stroke, that is, a pressure or discharge stroke and a suction or intake stroke, for each revolution of the shaft. Thus the shaft makes a one-half or 180 revolution during the pressure stroke and a one-half or 180 revolution during the suction stroke of the piston. Therefore, considering, for example, one end portion of the pump, the outer segmental portion 52 is displaced 180 from the inner segmental portion 62, and each segment includes, as a maximum, 180 of the shaft surface. With this arrangement, a single cylinder bore would communicate with the outer segment 52 during one-half of the complete piston stroke and with the inner segment 62 during the other half of the stroke.

For the practical purpose of effecting a pressure equalization in each cylinder immediately prior to'the start of both the discharge and suction strokes, the segments cover less than 180" of the surface, although they remain ,displaced 180 from each other. This leaves a slight land area 67 which will prevent direct communication between the cylinders and both the inlet and outlet ports during a short time at the beginning of the suction and discharge strokes. Consequently, the pressure in the cylinder will increase to a value approximating the pump discharge pressure before the cylinder is connected to the discharge port through one of the segments. This is known as precompression. Similarly, the suction pressure will in.- crease in a cylinder which remains closed during the initial part of the suction stroke, and the resulting expansion will lower the pressure approximately to that of the inlet pressure when the cylinder and inlet are connected through the other segment. Thus, pulsation of pressure due to valve action, together with the noise and other undesirable phenomena associated therewith, are substantially eliminated.

It should be kept in mind that the portion of the pump serving as the inlet and the portion serving as the-outlet depend entirely upon the direction of rotation of the shaft.

In order to prevent the rotation of the pistons 28 in cylinder bores 25 and 26, and to permit their nesting around the cam 29, segmental portions are removed intermediate their ends to provide a recessed surface 69. The follower pins 65 are inserted into the pistons in the center of the surface of the segmental cutout-portions. The peripheral surface of the barrel cam 29 rides against the surface 69 of the cutout portion of the respective pistons 28, as shown in Fig. 4. The amount of material longitudinally removed from the piston intermediate their ends need only be sufiicient to permit the full stroke travel of the pistons during their reciprocation, and-must be deep enough to permit the nesting of the pistons around the barrel cam without causing them to bind thereto and interfere with the pumping action. The pins are desirably mounted in bearings 71 secured within the pistons 28. The use of such a pin and bearing construction, permitting rotation of the pins as they are guided by the cam, reduces the friction between the pins 65 and the cam track 64 so that substantially all of the power input to the pump is converted to pumping energy.

When the cam track is at the proper angle relative to the shaft, it will be apparent that upon application of pressure fluid to either of the

ports

36 or 38 the pistons 28 will be caused to reciprocate and the cam 29 will thereby be driven by the pins 65 riding in the cam track 64. The shaft, secured to the cam, will be rotated in turn by the cam and energy'may be taken therefrom by a suitable means such as a gear or pulley.

it is under pressure or suction.

' V prevent the escape of air.

means of bolts 72 extending through suitable holes in the cylinder barrels and plates, and which may be readily removed when it is desired to replace a portion of the device. 3

Fig. 5 illustrates a modification of the present invention in which the device has been constructed to operate most efliciently as an air compressor. In applications in which it is necessary to compress a fluid against an existing pressure head, valve means of the poppet type, for example, which are positive in their action, are provided in the compressor head in order to prevent leakage of the fluid when valves in the end plates, along with suitable manifold channels, the basic pumping mechanism previously described may be adapted for use as a compressor. In the following description reference numerals corresponding to those used in describing this basic mechanism will be used where applicable along with the distinguishing In this modification the spaced barrel cylinders 21a and 22:: are provided at their outer endswith a discharge valve plate 75 and a suction valve plate'76, containing the discharge valves 78 andthesuction valves 79 respectively. The adjoining surfaces of these plates and the outer end surfaces of the cylinder barrels are machined smooth to prevent leakage when the plates are assembled with the barrels. This construction replaces the rotary valve previously described, the remainder of the device being constructed in the manner described above. Thus, the cylinder barrels are positioned in a spacedapart relationship so that pistons 28a may be reciprocated in their respective cylinders 25a and 26a by means of a barrel cam 29a which is secured to the drive shaft 24a. The pistons 28a nest around the cam 29a, the outer surface of which bears against the surface.

channel 82 communicating with the suctionports 81. A

port 84 and suitable fitting 85 provide means for connecting this annular channel to the high pressure tank. Oneway poppet-type discharge valves 78 are interposed between the discharge ports 81 and the annular manifold channel 32 to pass the compressed fluid outwardly from the compressor cylinders into the discharge channel 82. The intake ports 80, on the other hand, communicate directly with the atmosphere and areprovided with suitable poppet valves 78 permitting the flow of air into the chambers but closing uponthe compression stroke to The discharge and

suction valves

78 and 79 are biased to their seated or closed position, shown in the drawings, by a coil spring 86 or the like. Tie bolts 70a are provided for holding the compressor in assembled relation.

The compressor shown in Figs. 5, 6, and 7 is constructed for use especially in compressing air. In cases or applications in which it is desired to compress a gas other than air a manifold plate must be provided having a suitable inlet attachment to accommodate the compressor for such applications. 1

Referring now to Figs. 8 and 9, the manifold plate structure adapted to be mounted on the outer ends of the barrel cylinders 21b and 22b has been modified by providingthree plates, namelya discharge valve plate 90, a suction valve plate 91, and a manifold plate 92. Discharge ports 94 and suction ports 95 in the discharge valve plate 90 open into the cylinder bores 25b (Fig. 8). A valve seat is provided surrounding the discharge ports 94 against which the discharge valves 98 seat. Similarly, the suction valve plate 91 is provided with suction By providing poppet ports 99 and discharge ports 100 leading from the manifold plate 92 and communicating with the suction ports 95 and the discharge ports 94-, respectively, in the discharge valve plate 90. Valve seats are provided around the suction ports 99 in the suction valve plate against which the suction valves 101 seat. The manifold plate 92, as can be seen in Figs. 8 and 9, is formed with two concentric

annular channels

104 and 106. In the present modification the smaller diameter channel 104 communicates with the high pressure head storage through a port 105 and serves as the discharge manifold. The larger diameter channel 106, on the other hand, communicates, through a port 107, with the fluid supply source and serves as the suction manifold. The suction ports 99 and the discharge ports in the suction valve plate communicate with the suction manifold 106 and the discharge manifold 104, respectively. The

poppet valves

98 and 101 are, for example, of the positive type spring biased one-way poppet valves.

In each of the compressor modifications, only a portion of the device has been shown, although it will be apparent upon examination of the drawings that similar valve and manifold plates are provided on each end of the compressor unit. The compressors are therefore double acting with the same advantageous thrust eliminating characteristics.

We claim as our invention:

l. In a pressure fluid pump or the like, the combination comprising a housing defining a plurality of pairs of aligned cylinders arranged in circumferentially spaced relation, a shaft rotatably mounted in said hous ing, a barrel cam mounted on said shaft intermediate the opposed ends of said cylinders, a double acting piston reciprocably mounted in each of said pairs of cylinders,

each piston having an intermeidate segmental recess for cooperating with said barrel cam to prevent rotation of said piston in said cylinders, means on said piston and within said recess for operatively engaging said cam, said housing having a first pressure fluid port intermediate said pairs of cylinders and a second pressure fluid port alined axially with said shaft, and means for distributing pressure fluid to and from said cylinders through said housing ports as an incident to the relative rotation of said shaft and said housing comprising a pair of sleeves axially alined in said housing corresponding to said pairs of cylinders and journaling said shaft for rotation, said sleeves having a plurality of ports communicating with said cylinders and a plurality of ports communicating with said first housing port, said shaft having a passage extending substantially axially therein and in communication with said second housing port, and said shaft having segmental cut-out portions for conmeeting said sleeve ports from said cylinders alternately to said first housing port and to said second housing port as said shaft rotates.

2. In a pressure fluid pump or the like, the combination comprising a housing defining two groups of cylinders of each group being arranged in circumferentially spaced relationand the cylinders of one group being disposed in opposed relation to those of the other group and aligned therewith, a plurality of double acting pistons having the opposite ends thereof respectively received in corresponding cylinders of each group, a shaft coaxially disposed with respect to said groups of cylinders and rotatable with respect thereto, a barrel cam mounted upon said shaft intermediate said groups of cylinders and having an operative connection with each of said pistons for effecting reciprocation thereof in said cylinders upon relative rotation of said shaft and said housing, said connection between said cam and said pistons including means for constraining said piston to longitudinal movement, said housing having a first pressure fluid port intermediate said pairs of cylinders and a second pressure fluid port alined axially with said shaft, and

means for distributing pressure fluid to and from said cylinders through said housing ports as an incident to the relative rotation of said shaft and said housing comprising a pair of sleeves axially alined in said housing corresponding to said pairs of cylinders and journalling said shaft for rotation, said sleeves having a plurality of ports communicating With said cylinders and a plurality of ports communicating with said first housing port, said shaft having a passage extending substantially axially therein and in communication With said second housing port, and said shaft having segmental cut-out portions for connecting said sleeve ports from said cylinders alternately to said first housing port and to said second housing port as said shaft rotates.

3. In a pressure fluid pump or the like, the combination comprising a housing defining a plurality of pairs of aligned cylinders arranged in circumferentially spaced relation, a bore extending through said housing axially of said pairs of cylinders, a pair of sleeves press-fitted in said bore corresponding to said pairs of cylinders, a shaft rotatably mounted in said sleeves coaxially with said pairs of cylinders, a barrel cam fixed on said shaft and having a cam slot in the peripheral surface thereof, said cam being disposed intermediate the opposed ends of said cylinders, a double acting piston reciprocably mounted in each of said pairs of cylinders, each piston having a segmental recess intermediate its ends for cooperating with said barrel cam to prevent rotation of said piston in said cylinders, means rotatably mounted on said piston and within said recess for operatively engaging in said cam slot for effecting reciprocation of said piston in said cylinders upon relative rotation of said shaft and said housing, said housing having a first pressure fluid port intermediate said pairs of cylinders and a second pressure fluid port axially alined with said shaft, said sleeves having a pluality of ports communicating with said cylinders and a plurality of ports communicating with said first housing port, said shaft having a passage extending substantially axially therein and in communication with said second housing port, and said shaft having segmental cutout portions for connecting said sleeve ports from said cylinders alternately to said first housing port and to said second housing port as an incident to the relative rotation of said shaft and said sleeves.

4. In a pressure fluid pump or the like, the combination comprising a housing defining a plurality of pairs of alined cylinders arranged in circumferentially spaced relation, a shaft rotatably mounted in said housing, a barrel cam mounted on said shaft intermediate the opposed ends of said cylinders, a double acting piston reciprocably mounted in each of said pairs of cylinders, each piston having an intermediate segmental recess for cooperating with said barrel cam to prevent rotation of said piston in said cylinders, means on said piston and Within said recess for operatively engaging said cam, said housing having a first pressure fluid port intermediate said pairs of cylinders and a second pressure fluid port axially alined With said shaft, and means for distributing pressure fluid to and from said cylinders through said housing ports as an incident to the relative rotation of said shaft and said housing comprisinga pair of sleeves axially alined in said housing corresponding to said pairs of cylinders and journaling said shaft for rotation, said sleeves having a plurality of ports communicating with said cylinders and a plurality of ports communicating with said first housing port, said shaft having a passage extending substantially axially therethrough in communication with said second housing port, and said shaft having pairs of segmental cut-out portions for connecting said sleeve ports from said cylinders alternately to said first housing port and said second housing port as said shaft rotates, the segmental cut-out portions of each pair being spaced substantially apart from each other.

5. In a pressure fluid pump or the like, the combination comprising a housing defining a plurality of cylinders arranged in circumferentially spaced relation and opening into a space of circular cross-section, a shaft rotatably mounted in said housing and extending axially of said cylinders, a barrel cam mounted on said shaft and in said housing space, a piston reciprocably mounted in each of said cylinders, each piston having a segmental recess for cooperating with said barrel cam to prevent rotation of said piston in said cylinder, means on said piston and within said recess for operatively engaging said cam, said housing having a first pressure fluid port opening into said space and a second pressure fluid port axially alined with said shaft, and means for distributing pressure fluid t0 and from said cylinders through said housing ports as an incident to the relative rotation of said shaft and said housing comprising a sleeve axially alined in said housing corresponding to said cylinders and journaling said shaft for rotation, said sleeve having a plurality of ports communicating with said cylinders and a plurality of ports communicating with said first housing port, said shaft having a passage extending substantially axially therein and in communication with said second housing port, and said shaft having segmental cut-out portions connecting said sleeve ports from said cylinders alternately to said first housing port and said second housing port as said shaft rotates in said housing.

References Cited in the file of this patent UNITED STATES PATENTS 1,339,276 Murphy May 4, 1920 2,070,880 Blum Feb. 16, 1937 FOREIGN PATENTS 610,428 Great Britain Oct. 15, 1948