US3802813A

US3802813A - Fluid-displacement machines

Info

Publication number: US3802813A
Application number: US00298704A
Authority: US
Inventors: D Butler
Original assignee: Plessey Co Ltd
Current assignee: Plessey Overseas Ltd
Priority date: 1970-04-01
Filing date: 1972-10-18
Publication date: 1974-04-09
Anticipated expiration: 1991-04-09

Abstract

A pump in which fluid is pumped by means of an annulus gear and several pinions intermeshing with the annulus gear. Fluid inlet and outlet ports are arranged on either side of each zone of intermesh between the annulus gear and each one of the pinions. Each inlet port is so positioned with respect to its pinion that fluid is introduced to the pinion at the side face of the pinion. Also, each pinion is so shaped as to progressively close the side face of the annulus gear from its root circle towards the tips of its teeth. The pump also has external flow connection pipes.

Description

United StatesPatent [191 Butler -[4 Apr. 9, 1974 [54] FLUID-DISPLACEMENT MACHINES 1,088,836 3/1914 Nielsen 418 165 [75] Inventor: Denis Victor Butler, Fareham, FOREIGN PATENTS OR APPLICATIONS England 112.922 8/1941 Australia 418/165 [73] Assignee: The Plessey Company Limited,

f -d Essex, England Primary Examiner-Carlton R. Croyle Assistant Examiner-John J. Vrablik [22] Filed: 1972 Attorney, Agent, or FirmScrivener, Parker, Scriv- 21 Appl, No.: 298,704 ener & Clarke [63] C Related U.S. ApplsicatloNn Dzaia l A l 57] ABSTRACT g xg gxg 0 pnl A pump in which fluid is pumped by means of an annulus gear and several pinions intermeshing with the 52 US. Cl. 418/165, 418/200 annulus gear- Fluid inlet and Outlet Ports are arranged [5 1] CL n FOR 1/00 F03c 3/00, F04: 1 /00 on either side of each zone of intermesh between the [58] ield of Search 418/9, 10, 15, 165, 200; nulus gear and each one of the pinions. Each inlet 73/253 261 port is so positioned with respect to its pinion that fluid is introduced to the pinion at the side face of the [56] References Cited pinion. Also, each pinion is so shaped as to progres- UNITED STATES PATENTS sively close the side face of the annulus gear from its root circle towards the tips of its teeth. The pump also lSizangztsen 4l8/l65 has external f connection pipes. 2:699:726 1/1955 Quinn 418/9 4 Claims, 3 Drawing Figures FLUID-DISPLACEMENT MACHINES This invention relates to a fluid-displacement machine and is a Continuation-in-Part application of our application Ser. No. 24591 filed Apr. l, 1970 and now abandoned.

It is an object of the invention to provide a fluiddisplacement machine including the combination of an annulus gear with a plurality of pinions. In one mode of operation of the fluid-displacement machine, a number of separate inlet flows are combined into a single outlet flow, with exactly metered quantities of fluid being drawn from each inlet flow and thus enabling maintenance of a desired mixture ratio between the liquid supplied by the individual inlets. In another mode of operation of the fluid-displacement machine, a flow of liquid drawn from a common inlet supply is divided at predetermined ratios between a number of consumers which may operate at different pressures, without the pressure or quantity supplied to one consumer being effected by the pressure required by another consumer.

Accordingly, this invention provides a fluiddisplacement machine which comprises, in combination:

a housing having an annular chamber and a plurality of part-circular pocketspenetrating the inner circumference of said annular chamber at circumferentially spaced positions;

an annulus gear freely rotatably mounted in said annular chamber with its sides in sealing contact with the housing walls and its teeth in sealing co-operation with said inner circumference on the annular chamber between adjacent pockets;

a plurality of pinions with one pinion being accommodated in each of said pockets in intermeshing'relation with the annulus gear, with at least one of the said pinions being provided with a drive shaft, with the sides of each pinion in sealing contact with the housing walls, and with the teeth of each pinion in sealing cooperation with the circumferential wall of the pocket;

a first and a second port, one forming an inlet port and one forming an outlet port, being respectively arranged at opposite sides of each zone of intermesh of the annulus gear with each pinion, and said inlet port (a) being so positioned with respect to its pinion that fluid is introduced to said pinion at the side face of said pinion and (b) being so shaped as to progressively close the side face of the annulus gear from its root circle towards the tips of its teeth;

first external flow connection means joined to all of said first ports;

second external flow connection means joined to at least one but not all of said second ports; and

third external flow connection means isolated from said at least one of the second ports and joined to at least one second port which is not joined to said second flow connection means.

Preferably, the fluid-displacement machine includes a plurality of banks of annuli and pinions having parallel axes, at least one pinion of each bank being coaxial with a pinion of each other bank. Also preferably, said second and third external flow connection means are respectively joined to the different numbers of the said second ports. Each of said second ports may be joined to a separate external flow connection means.

' the space between each pair of teeth on the pinions acts The fluid-displacement machine of the present invention may be very compactly constructed, the compactness being allowed by virtue of the fact that the pinions are housed inside of the annulus gear and in part circular pockets.

Since the fluid is introduced at the side faces of the pinions, the fluid can relatively easily be introduced and retained between the teeth of the pinions. There is substantially no tendency for the fluid to be thrown out as the pinions are rotating. Hitherto, in fluiddisplacement machines, the fluid has often been introduced radially directly towards the teeth of the pinions and this radial introduction of the fluid has often resulted in much of the introduced fluid being thrown out again by centrifugal force as the pinions are rotating. Such fluid rejection is especially noticeable when the pumps are working at high rotational speeds.

Each inlet port in the fluid-displacement machine of the present invention is shaped so as to progressively close the side face of the annulus gear from its root circle towards the tips of its teeth. This shaping is extremely advantageous in that it largely prevents any liquid from being forced back from the annulus gear into the-inlet port and, so long as the volume of gas does not exceed that of the liquid in the entering mixture, the pinions will take most of the gaseous content round their own circumference to the outlet port with which each pinion is in contact, while the liquid will be carried round by the annulus gear to the outlet port cooperating with the next pinion.

When the fluid-displacement machine is used as a gear pump, it can work with aminimum number of teeth on each pinion. Thus, for example, each pinion may have as little as ten teeth. It is often preferred to employ pinions with a small number of teeth because as a receptacle for fluid. One deep receptacle can in general contain far more fluid than two or three shallow receptacles. By way of example, it may be mentioned that a gear pump using pinions having ten teeth may have a pumping capacity which is as much as two and a half times that of a gear pump having the same design but using pinions having twenty five teeth. As indicated, Applicants pump is so designed that pinions having a small number of teeth can be readily employed if desired. The ability to reduce the number of pinion teeth has not always hitherto been available with fluid-displacement machines in view of various mesh and sealing requirements. For example, in some hitherto known machines, each pinion may require at the same time teeth to be in meshing engagement with an annulus gear, teeth to be in engagement with a central gear, teeth to be in sealing engagement with various lugs, and teeth between the various sealing or meshing parts for carrying fluid. It will thus be apparent that a considerable number of teeth is required.

The invention will now be described by way of example and with reference to the accompanying drawing, in which:

FIG. 1 is a somewhat diagrammatic section at right angles to the gear axes of one embodiment of a fluiddisplacement machine in which three pinions are provided;

FIG. 2 is an elevation in axial section of a modified embodiment of a fluid-displacement machine which is equipped with two annulus gears.

Referring to the drawing, and especially to HO. 1, there is shown-an annulus gear I mounted for free rotation in an annular groove 2 of a pump housing 3. The annulus gear 1 is centered in the groove 2 by cooperation at the tips of its teeth 4 with a core portion 5 of the housing. Three

pinions

6, 7 and 8 are accommodated in bores 9 in the core portion 5 so that each of the pinions intermeshes with the teeth 4 of the annulus gear 1 while the pinions are isolated from each other by the core portion 5. The tips of the teeth 10 of each

pinion

6, 7, 8 are in sealing contact with the core portion 5. At least one of the

pinions

6, 7, 8 is provided with a drive shaft 11, as shown in the present case of pinion 6. The drive shaft 11 for pinion 6 extends through the wall of the housing 3 for connection to a motor or a load as the case may be. In view of the engagement of the annulus gear 1 with each of the

pinions

6, 7, 8, it is sufficient to drive only one pinion 6 in order to achieve co-ordinated rotation of the annulus gear 1 and all of the three

pinions

6, 7, 8.

The pump housing 3 is further formed with two sets of ports forming axial inlets and outlets. A first set of the ports 12a, 12b and 12c are arranged at that side of each zone of engagement of the annulus gear 1 which, when the machine operates as a pump with the gear 6 driven in the direction of the arrow A, is the inlet side. The other set of ports 13a, 13b and 13c is at that side of each zone of engagement which ,in these circumstances forms the delivery or outlet side. The actual shape of the inlet ports has not been shown in FIG. 1 for convenience.

With the above mentioned arrangement of the inlet and delivery ports, so called sideentry characteristics can be achieved which offer various advantages.- Thus, when the working fluid is a liquid and a gas mixture, for example oil containing some air, centrifugal force will ensure that the liquid content will be impelled outwardly by centrifugal force so as to move into the root portions of the tooth spaces of the annulus gear 1. The shape of the entry ports is so arranged as to progressively close the side faces of the annulus gear 1 from its root circle towards the tips of its teeth, thereby largely preventing any liquid from being forced back from the annulus gear into the inlet port. Also, so long as the volume of gas does not exceed that of the liquid in the entering mixture, each pinion will take most of the gaseous content of the mixture around its own circumference to the outlet port co-operating with the other side of the same pinion, while the liquid content of the mixture will be carried round by the annulus gear 1 to the outlet port co-operating with the next pinion. In this manner, each outlet port will receive gas and liquid largely preseparated due to their arrival by different ways. A further advantage of the side-entry feature is that high pitch-line velocities can be employed without causing an unduly high pressure drop at the ports.

One set of ports, for example the pump inlet ports, may be combined in one side plate of the pump atone side of the gears while the opposite side plate of the pump may be provided with individual outlets. Conversely individual inlets may be used in one side plate and the outlets combined in the side plate at the other side. The first alternative corresponds to the use of the machine as a metering pump and, in this alternative, the pressures in the various delivery lines may differ from each other and may vary without affecting the pressure in the other delivery lines. The second alterna tive corresponds to the use of the machine as a scavenge pump and, in this alternative, each inlet may accept an equal amount of flow of scavenging liquid irrespective of variations in the pressures in the individual scavenge lines leading to the pump.

The inlet ports 12a, 12b and have been assumed to be at the back of the plane of section and are shown in the drawing as intercommunicating, by a passage 14 with a common inlet line 15. The outlet ports 13a, 13b and 130, which have been shown in chain-dotted lines to indicate that they are assumed to be arranged at the front of the plane of section, are shown as leading to

separate outlets

16a, 16b and respectively. it will be readily apparent that since all the

pinions

6, 7, 8 cooperate with one and the same annulus gear I, the volumes of the individual tooth gaps of each of the

pinions

6, 7, 8 are equal to each other. Thus, the rates of volume transfer round each of these pinions as well as along each of the three parts of the annulus gear 1 interconnecting its zones of intermesh with each of the

pinions

6, 7, 8 are equal. When the machine is operated as a pump in the manner just referred to any liquid entering through inlet 15 will therefore be uniformly distributed between the three

outlets

16a, 16b and 160. However, it will readily appreciated that if desired, two of the outlets, for example 16a and 16b may be joined to each other. This will allow the attainment of two resultant outlet flows, one comprising the combined flows of outlwt 16a .and 16b and the other comprising the individual flow of outlet 160. in this case, the incoming liquid is distributed between two resultant outlet flows at a ratio of 2:1. Other ratios of distribution may be achieved when more than three pinions are employed by combining suitably connected numbers of individual outlets. It will also be appreciated that, instead of providing a single inlet and a number of individual outlets, the arrangements could be reversed so as to combine the flows received by a number of individual inlets into a single outlet flow. This could, for example, be achieved by simply reversing the direction of rotation of the machine by driving the pinion 6 in a direction opposite to that of the arrow A.

Another modification which may be made within the scope of the invention consists in the provision of a plurality of gear banks each comprising an annulus gear and number of pinions. Preferably at least the drive pinions of all the banks will be arranged coaxially so that they can be mounted on a common drive shaft. The axial width and/or, if desired, the tooth pitch employed may be different in each individual bank in accordance with the volumetric requirements of the intended use. In such a plural bank machine, coupling is possible not only between individual inlets or outlets of one and the same bank-but also between one or more inlets or outlets in one bank with one or more inlets or outlets respectively of one or more other banks. This greatly increases the variety of ratios of flow distribution or flow combination that can be achieved.

in the plural bank machine illustrated in FIG. 2, two annulus gears l and 21 are rotatably mounted in

housing plates

3 and 23 respectively. The gears 1 and 21 are arranged at opposite sides of a centre plate 20 and are arranged to be drivingly engaged respectively by two

pinions

6 and 26 of different diameters. These pinions are secured coaxially on a common shaft 11, by which they may be driven jointly. The housing plate 3 is shaped similarly to that of the housing 3 illustrated in FIG. 1. Thus, the housing plate 3 is provided with three pinions, only pinions 6 and 7 being shown. The three pinions co-operate with inlet ports and outlet ports respectively arranged at the disengagement side and the approach side of each zone of engagement with the annulus gear 1. There are thus three inlets ports and each inlet port communicates, by a line 14, with a comon inlet line in the centre plate 20. Similarly, there are three outlet ports and each outlet port leads to a separate outlet, only

outlets

16a and 16b being shown in FIG. 2.

The arrangement in the other housing plate 23 is basically similar to that in the housing plate 3 but its annulus gear 21 is smaller in diameter than the annulus gear 1 in the housing plate 3. Three pinions are situated in the housing plate 23. Only two

pinions

26, 27 are shown. All three pinions are somewhat smaller in diameter than the pinions in the housing plate 3. Thus, the circumferential velocity of the pitch circle of the pinions in the housing plate 23 and of the annulus gear 21 is smaller than that of the corresponding elements in the housing 3. In this connection, it will also be'observed that the axesof rotation of the annulus gear 21 and of each of the pinions in the housing plate 23 may be offset relative to the respective axes of the annulus gear 1 and two of the pinions in the housing plate 3, so long as the drive pinion 26 in housing plate 23 is coaxial with the drive pinion 6 in housing plate 3.

Similarly to the case of the device of FIG. 1, the inlet port and the outlet port at opposite ends of each zone of engagement are arranged at opposite sides of the

housing plate

3 or 23, the inlet port being connected to a common inlet passage 15 in the centre plate as aforesaid. The outlet port 36a co-operating with the pinion 26 is shown to be interconnected with the corresponding outlet port 16a for the housing 3. Also, a secondport 36b for the housing plate 23 is shown separate from the corresponding housing port 16b for the housing plate 3 and may be either kept separate or joined with a third port (not shown) for the housing plate 23.

What we claim is: l. A fluid-displacement machine which comprises in combination:

a housing having an annular chamber and a plurality of part circular pockets penetrating the inner circumference of said annular chamber at circumferentially spaced positions;

an annulus gear freely rotatably mounted in said annular chamber with its sides in sealing contact with the housing walls and its teeth in sealing cooperation with said inner circumference of the annular chamber between adjacent pockets:

a plurality of pinions with one pinion being respectively accommodated in each of said pockets in intermeshing relation with the annulus gear, with at least one. of said pinions being provided with a drive shaft, with the sides of each pinion in said sealing contact with the housing walls, and with the teeth of each pinion in sealing co-operation with the circumferential wall of the pocket;

a first port and a second port, one forming an inlet port and one forming an outlet port, being respectively engaged at opposite sides of each zone of intermesh of the annulus gear with each pinion, said first and second ports being the only ports in the fluid-displacement machine engaged by each said pinion, and each said inlet port (a) being so positioned with respect to its pinion that fluid is introduced to said pinion at the side face of said pinion and (b) being so shaped as to progressively close over the whole of its length the side face of the annulus gear from its root circle towards the tips of its teeth;

first external flow-connection means joined to all of said first ports;

second external flow-connection means joined to at least one but not all of said second ports; and

2. A fluid-displacement machine as claimed in claim 1 wherein said second and third external flow connection means are respectively joined to different numbers of said second ports.

3. A fluid-displacement machine as claimed in claim 1, in which each of said second ports is joined to a separate external flow connection means.

4. A fluid-displacement machine as claimed in claim 1, which includes a plurality of banks of annuli and pinions having parallel axes, at least one pinion of each bank being coaxial with a pinion of each other bank.

Claims

1. A fluid-displacement machine which comprises, in combination: a housing having an annular chamber and a plurality of part circular pockets penetrating the inner circumference of said annular chamber at circumferentially spaced positions; an annulus gear freely rotatably mounted in said annular chamber with its sides in sealing contact with the housing walls and its teeth in sealing co-operation with said inner circumference of the annular chamber between adjacent pockets: a plurality of pinions with one pinion being respectively accommodated in each of said pockets in intermeshing relation with the annulus gear, with at least one of said pinions being provided with a drive shaft, with the sides of each pinion in said sealing contact with the housing walls, and with the teeth of each pinion in sealing co-operation with the circumferential wall of the pocket; a first port and a second port, one forming an inlet port and one forming an outlet port, being respectively engaged at opposite sides of each zone of intermesh of the annulus gear with each pinion, said first and second ports being the only ports in the fluid-displacement machine engaged by each said pinion, and each said inlet port (a) being so positioned with respect to its pinion that fluid is introduced to said pinion at the side face of said pinion and (b) being so shaped as to progressively close over the whole of its length the side face of the annulus gear from its root circle towards the tips of its teeth; first external flow-connection means joined to all of said first ports; second external flow-connection means joined to at least one but not all of said second ports; and third external flow connection means isolated from said at least one of the second ports and joined to at least one second port which is not joined to said second flow connection means.