ROTARY HYDRAULIC MACHINE

Abstract: A split-discharge balanced dual-lobe vane-type rotary hydraulic machine (10, 110) that comprises a housing (51), a rotor (12) mounted within the housing (51) and having a plurality of radially extending peripheral slots (16), and a plurality of vanes (18) individually slidably mounted in the rotor slots. A cam ring (20) within the housing (51) surrounds the rotor (12) and has a radially inwardly directed surface forming a track (22) for sliding engagement with the vane (18). Opposed symmetrical pressure cavities (24) are formed between the cam ring surface (22) and the rotor (12), and fluid inlet and outlet passages in the housing are coupled to the fluid pressure cavities (24). The fluid inlet and outlet passages include a fluid inlet port (26) opening into each cavity (24) adjacent to one circumferential edge thereof, a first fluid outlet port (30) opening into each cavity adjacent to the opposing circumferential edge thereof, and a second fluid outlet port (32) opening into each cavity at a position circumferentially between the inlet and first outlet ports.

Description: The present invention is directed to a rotary hydraulic machine according to the features of the preamble of claim 1. A known machine of that kind (GB-A-758,875) comprises a pump having two outlet paths for each pump cavity and a flow control valve for making output flow rate essentially constant. When the pump rotates with higher speeds, excess flow from the first and second flow paths is returned to a reservoir and to inlet, so that the remaining output flow rate can be kept constant. The first and second flow path join to form a common discharge line which carries the flow of substantially constant rate. It is desirable to match fluid displacement in machines of the subject type to operating characteristics of the system with which the machine is to be associated. For example, maximum displacement of a vane-type fuel pump is coordinated with maximum fuel requirements of the associated engine application. However, system requirements typically vary with operating conditions, so that a fixed displacement machine designated as a function of the most demanding operating conditions may function with less than desired efficiency under other operating conditions. In the examplary case of a fuel pump, fuel flow requirements under engine starting conditions greatly exceed requirements during normal operation. It has heretofore been proposed to provided relatively complex and expensive valving arrangements (flow or fuel controls) at the pump outlet to meter a portion of the pump output to the engine as a function of engine demand, while returning the remainder to the pump inlet causing fuel heating from the throttling effects. A general object of the present invention, therefore, is to provide a rotary hydraulic machine of the subject type in which effective machine displacement can be controlled as a function of demand, and yet is inexpensive to manufacture and assemble as compared with variable-displacement rotary hydraulic machines of the prior art. Another object of the present invention is to provide a machine of the described character that is compact in assembly. A further and more specific object of the invention is to provide a split-discharge balanced dual-lobe vane-type machine design that may be employed as a pump, motor, flow divider, pressure intensifier or the like with minimum modification to overall design principles and components. Summary of the Invention The present invention contemplates a vane-type rotary hydraulic machine that comprises a housing, a rotor mounted within the housing and having a plurality of radially extending peripheral slots, and a plurality of vanes individually slidably mounted in the rotor slots. A cam ring within the housing surrounds the rotor and has a radially inwardly directed surface forming a track for sliding engagement with the vane. At least one fluid pressure cavity is formed between the cam ring surface and the rotor, and fluid inlet and outlet passages in the housing are coupled to the fluid pressure cavity. In accordance with a distinguishing feature of the present invention, the fluid inlet and outlet passages include a fluid inlet port opening into the cavity adjacent to one circumferential edge thereof, a first fluid outlet port opening into the cavity adjacent to the opposing circumferential edge thereof, and a second fluid outlet port opening into the cavity at a position circumferentially between the inlet and first outlet ports. The first and second outlet ports thus cooperate with the inlet port and the fluid pressure cavity effectively to form a dual displacement machine in which each displacement may be coordinated with operating system characteristics at one nominal design operating condition, thereby forming a machine that not only matches the operating system at two specific system conditions, but also more closely matches system requirements over the entire range of system conditions. In accordance with presently preferred embodiments of the invention, the rotary hydraulic machine comprises a split-discharge balanced dual-lobe machine in which the cam ring and rotor cooperate to form diametrically opposed symmetrically positioned fluid pressure cavities. A fluid inlet port opens into each cavity at the leading edge thereof with respect to the direction of rotor rotation, a first fluid outlet port opens into each cavity adjacent to the trailing edge thereof, and a second fluid outlet port opens into each cavity circumferentially between the associated inlet and first outlet ports. The ports are symmetrically diametrically positioned with respect to the rotor for enhanced balance. The housing in the preferred embodiments of the invention comprises a cup-shaped enclosure or shell, and first and second backup plates telescopically received within the cup-shaped enclosure and having the rotor sandwiched therebetween. The fluid inlet includes a radially orientated inlet opening aligned with the rotor. The first and second fluid outlets include a pair of annular channels on a radially facing surface of one of the backup plates, a first passage in the backup plate coupling a first of the channels to both of the first cavity outlet ports, a second passage in the backup plate coupling the other of the channels to both of the second cavity outlet ports, and a pair of radially orientated outlet openings in the enclosure in respective radial alinement with the channels. Most preferably, the machine of the present invention further includes one or more control valves for selectively directing fluid from one of the cavity outlet ports to inlet port or to a secondary flow circuit. The invention finds particular advantage in aircraft fuel systems by permitting the displacement of the pump to be split or selected to match engine fuel system needs more closely. When pump outlets are combined, the total displacement of the pump is available for engine needs at the maximum flow capability of the combined displacements, particularly at engine light-off conditions or at maximum engine fuel flow demands such as take-off. When the flows are split, the engine system now has two separate and distinct flow circuits to use for engine needs. One may be used for running the engine and the second for airframe motive flow, secondary engine fuel system, or returned to the aircraft tank or to the pump inlet. The invention enables a reduction in the heat rise in the fuel system by using a pump more ideally sized for the engine needs, and by reducing the amount of fuel bypassed in typical engine fuel controls. Brief Description of the Drawings The invention, together with additional objects, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which: FIG. 1 is a typical cross-sectional diagram of a vane-type rotary hydraulic machine in accordance with the present invention; FIG. 2 is a schematic diagram of a hydraulic system employing the machine in FIG. 6 as a fluid flow mechanism capable of providing flow to two individual and distinct circuits; FIG. 3 is a sectional view of a fluid flow divider embodying the principles of the present invention in accordance with one presently preferred embodiment thereof; FIGS. 4 and 5 are fragmentary sectional views taken substantially along the respective lines 4-4 and 5-5 in FIG. 3; FIG 6. is a typical cross-sectional diagram similar to that of FIG. 1 showing a rotary hydraulic vane-type pumps in accordance with another embodiment of the invention; FIG. 7 is a schematic diagram of a hydraulic system employing the pump of FIG. 6; FIG. 8 is a schematic diagram of a vane-type rotary hydraulic machine in accordance with the invention in a flow divider circuit, and FIG. 9 is a schematic diagram of a vane-type rotary hydraulic machine in accordance with the invention in a pressure intensifier circuit. Detailed Description of Preferred Embodiments FIG. 1 schematically illustrates a split-discharge dual-displacement balanced dual-lobe rotary hydraulic machine 10 in accordance with a presently preferred embodiment of the invention as comprising a rotor 12 having a circular periphery and mounted for free rotation about a shaft 14. Rotor 12 has a circumferential array of radially directed slots 16 in which a corresponding plurality of vanes 18 are radially slidably disposed. A cam ring 20 radially surrounds rotor 12 and has an inwardly directed cam ring surface 22 that cooperates with rotor 12 and vanes 18 to form a pair of diametrically opposed symmetrical fluid pressure cavities 24. Hydraulic fluid is fed through inlet passages to a pair of radially opposed inlet ports 26, each opening into an associated cavity 24 at the leading edge thereof with respect to the direction 28 of rotation of rotor 12. Likewise, fluid outlet passages receive fluid from a pair of diametrically opposed first outlet ports 30 that open into respective cavities 24 adjacent to the trailing circumferential edges thereof with respect to direction 28 of rotation. Fluid under pressure is also fed by appropriate passages to a chamber 33 positioned beneath each vane 18 for urging the vanes radially outwardly against cam ring surface 22. To the extent thus far described, machine 10 is of generally conventional construction. In accordance with the present invention, a second pair of diametrically opposed outlet ports 32 open into respective cavities 24 at positions circumferentially between the associated inlet port 26 and first outlet port 30. Thus, fluid received at each inlet port 26 is discharged first at an adjacent outlet port 32 and then at a outlet port 30, with fluid discharge pressure at each outlet port being a function of contour of cam ring surface 22. There is, of course, a circumferential dwell region between each successive pair of ports, coordinated with circumferential spacing between vanes 18, so that the ports are isolated from each other in operation. FIG. 8 is a schematic diagram of machine 10 connected as a flow divider for the dividing of the incoming fluid flow into two circuits having the total equivalent flow of the incoming fluid divided into two circuits at a pre-determined ratio. Inlet ports 26 receive fuel under pressure from a source 34. Ports 32 are connected together to form a second discharge A for a portion of the incoming flow 34. Ports 30 are connected together to form a first discharge B accepting the balance of the incoming flow 34. The flow division between ports 32 and 30 may be of any given amount so long as the total is the same as the inlet flow from source 34. FIG. 9 is a schematic diagram of machine 10 connected as a pressure intensifier for increasing the pressure level of a portion of the fluid flow to a higher pressure level (pumping function) while returning the remaining portion to a lower pressure (motor function). Inlet ports 26 receive fuel under pressure from a source 34. Ports 32 are connected together to form a first discharge A at a higher pressure (pumping function) to provide a fluid flow source at a higher pressure than normally feed from pressure source 34. Ports 30 are connected together to form a second discharge B returning the fluid to the tank or to the inlet for fluid source 34. The function of ports 32 and 30 may be reversed depending on the particular fluid circuit needs. FIGS. 3-5 illustrate a working embodiment of pressure intensifier 10 as comprising a cup-shaped enclosure or shell 42 having a stepped radially inwardly directed wall 44. A pair of backup plates 46, 48 are telescopically received within enclosure 42, backup plate 48 being fastened by screws 50 to the open axial edge of enclosure 42 to form the complete housing 51, and backup plate 46 being spaced by a fluid cavity 58 from the enclosure base. A pair of opposed pressure or port plates 60, 62 are fastened by pins 64 to the axially opposed surfaces of backup plates 46, 48. Cam ring 20 is mounted by pins 66 to backup plate 46 between plate 46 and plate 48. Rotor 12 is mounted for free rotation on a stub shaft 14 that is captured between backup plates 46, 48 and held by a pin 70 against rotation with respect thereto. A pair of cam plates 72, 74 are mounted by pins 64 within opposing pockets of rotor 12, and have peripheries that engage the inner edges of vanes 18 and thereby positioned the vanes in radial proximity to the opposing surface 22 of cam ring 20. An internally threaded inlet opening 76 extends radially through the peripheral wall of enclosure 42 in radial alignment with rotor 12. A passage 78 in backup plate 48 connects inlet 76 with a channel 80 that extends circumferentially around the radially-facing wall of backup plate 48. Channel 80 is connected by another passage 78 to the other inlet port 26. Ports 26 are formed as radially tapering slots in pressure plates 60, 62 (FIGS. 3 and 4). Each first outlet port 30 is formed as axially aligned apertures in both pressure plates 60, 62, the apertures being interconnected by a passage 82 (FIGS. 3 and 4) that extends through cam ring 20, and by a passage 84 (FIG. 3) that extends axially into backup plate 26 to open into a radially outwardly directing annular channel 86 in the side surface thereof. Likewise, each second outlet port 32 is formed as axially aligned apertures in backup plates 60, 62 that are interconnected by passages 88 extending through the pressure plates and the cam ring, and by passages 90, 91 (FIG. 3) to a radially outwardly facing annular channel 92 in the sidewall of backup plate 46. A pair of radially orientated internally threaded outlet openings 94, 96 extend through the sidewall of enclosure 42 in radial alignment with channels 92, 86 respectively to form discharge A and B discharge as previously described. Inlet 76 is also connected by a passage 98 (FIG. 3) in backup plate 46 to cavity 58 for urging backup plate 46 toward rotor 12 and backup plate 48. Likewise, undervane chambers 32 receive fluid under pressure by passages (not shown) in the backup plates and pressure plates. Fluid at undervane pressure is available for reference through passages 100 in rotor 12, 102 in shaft 14 and 104 in backup plate 46. Passage 104 is normally blocked by a plug 105. Figs. 6 and 7 illustrate a rotary hydraulic machine 110 in accordance with the present invention configured as a rotary vane pump in which rotor 12 is splined to shaft 14, which in turn extends from the pump housing for coupling to a suitable source of motor power (not shown). Cam ring surface 22 is contoured in the configuration of Fig. 6 such that first outlet ports 30 form the primary or high-pressure outlet ports, and second outlet ports 32 form the secondary lower-pressure outlet ports. Ports 30 are connected through collecting lines 129 and a common discharge line 130 to an engine fuel control system 112 (Fig. 7). Ports 32 are individually connected through lines 113 to associated directional valves 114 for selectively connecting ports 32 either to the discharge line 130 through lines 115 and check valves 116 and to the input of engine control system 112, or through lines 117 to the input ports 26 of pump 110. Engine control system 112 provides control lines 119 to directional valves 114, and also provides a return path 121 for fuel to the inlet of pump 110 through a filter 118. During periods of high engine fuel demand, such as during starting, control 112 limits pressure in control line 119 to directional valve 114, so that the directional valves assume this first position illustrated in Fig. 7 under control of associated springs 120 and connect secondary pump outlet ports 32 to the discharge line 130. On the other, when such secondary pump outlet fuel is not required for engine operation, control 112 provides for high pressure in control line 119 shifting the spools of the directional valves 114 in their second positions to interconnect ports 32 with inlet ports 26 through lines 113, 117, so that excess fuel is returned to the fluid receiving means 34 and the pump inlet 26 and not fed to the engine. Thus, pump energy is conserved. Fig. 2 is a schematic diagram of machine 110 connected as a fuel pumping mechanism for control of fuel flow to a jet engine or the like. Inlet ports 26 receive fuel from a source 34 and a booster 36. Ports 32 are connected together to form a second discharge A coupled to a solenoid valve 38 that normally feeds fluid from discharge A to secondary engine circuits (or to the airframe tank or to inlet ports 26). Ports 30 are connected together to form a first discharge B connected to a fuel control system 40 for normal engine operation. The fuel from discharge A is normally directed to inlet ports 26, and is selectively directed from discharge A to the engine during periods of high fuel demands, such as when starting the engine. Solenoid valve 38 may be activated by associated control electronics (not shown) for coupling discharge A to discharge B at the inlet to fuel control system 40 and circulating all fuel through machine 110 when the engine is idle. Thus, in the embodiment of Figs. 6 and 2, machine 110 is configured as a pumping mechanism in which the ratio of the cam rise from the inlet port to the cam fall leading to discharge ports 32 determines the flow division ratio. Discharge ports 30 function not only to reposition the vanes for the next pumping cycle, but also to provide a secondary fluid outlet at a selected pressure for use as desired.

Claims: A rotary hydraulic machine (10, 110), especially fuel pump, comprising: a housing (42, 46, 48), a rotor (12) mounted for rotation within said housing and having a plurality of radially extending peripheral slots (16) with vanes (18) individually slidably mounted therein, cam ring means (20) within said housing surrounding said rotor (12) and having a radially inwardly directed vane track surface (22), at least one fluid pressure cavity (24) between said surface (22) and said rotor (12), fluid inlet means including means (76) for receiving hydraulic fluid and directing such fluid to said cavity (24) through a cavity inlet port (26) adjacent to one circumferential edge of said cavity (24), fluid discharge means including a first cavity outlet port (30) adjacent to an opposing circumferential edge of said cavity (24) for directing fluid from said cavity (24) along a first outlet path, and a second cavity outlet port (32) positioned circumferentially of said rotor (12) between said inlet port (26) and said first outlet port (30) for directing fluid from said cavity (24) along a second flow path, and valve means (38, 114, 116) for returning a portion of the fluid from said outlet paths back to said fluid inlet means, characterized in that said discharge means includes a first and a second circuit (A, B) different from one another and showing different pressure and flow characteristics, and in that said valve means (38, 114) is of the type to be selectively controlled and arranged to return the fluid flow of one circuit (A) back to said fluid inlet means or to direct that fluid flow into a common discharge line (130) of said discharge means, or to have said first and second circuits (A, B) further separated. The machine set forth in claim 1, wherein said common discharge line (130) is the inlet to an engine feed control system (40, 112) which comprises means (119) for selectively controlling said valve means (38, 114). The machine set forth in claim 2, wherein said feed control system (40, 112) includes a further return path (121) for the fluid. The machine set forth in any of claims 1 to 3, wherein said cam ring (20) and rotor (12) are constructed and arranged to form a pair of said cavities (24) each radially symmetrically positioned with respect to the other, also with respect to said inlet port (26) and said first (30) and second (32) outlet ports. The machine set forth in any of claims 1 to 4, wherein said inlet port (26) is an opening into said cavity (24) at a leading circumferential edge thereof with respect to direction of rotation of said rotor (12) within said housing (42, 46, 48), said first fluid outlet port (30) is an opening into each said cavity (24) at a trailing circumferential edge thereof with respect to direction of rotation of said rotor (12), and said second fluid outlet port (32) is an opening into said cavity (24) circumfernentially between said inlet port (26) and said first outlet port (30). The machine set forth in claim 5 wherein said housing comprises a cup-shaped enclosure (42), and first and second backup plates (46, 48) telescopically received within said cup-shaped enclosure (42) and having said rotor (12) sandwiched therebetween. The machine set forth in claim 6 wherein said first fluid inlet includes a radially oriented inlet opening (76) in said enclosure (42) in radial alignment with said rotor (12); and wherein said first and second fluid outlets include a pair of annular channels (86, 92) on a radially facing surface of one (46) of said backup plates, first passage means (84) in said one backup plate (46) coupling a first (86) of said channels to said first outlet ports (96), second passage means (90) in said one backup plate (46) coupling a second (92) of said channels to said second outlet ports (94), and a pair of radially oriented outlet openings (94, 96) in said enclosure (42) in respective radial alignment with said channels (86, 92). A rotary hydraulic machine set forth in any of claims 1 to 7, wherein said valve means (38; 114, 116) having a valve inlet port and a first and a second valve outlet port; said second cavity outlet port (32) being connected (113) to said valve inlet port, said first valve outlet port being connected (115) to said first cavity outlet port (30) and said second valve outlet port being connected (117) to said means (34) for receiving hydraulic fluid. A rotary hydraulic machine set forth in claim 8 wherein said valve means (38; 114, 116) include a directional valve (38; 114) having a first position to connect said valve inlet port to said first valve outlet port and a second position to connect said valve inlet port to said second valve outlet port. A rotary hydraulic machine set forth in claim 9 wherein said directional valve (38; 114) is connected to means (40; 112) adapted to receive flow demand signals and control said directional valve (38; 114) in its first or second positions.

Inventors: HANSEN, LOWELL D., HURLEY, RICHARD J., SCHWEITZER, JEAN J., ZOYA, WALTER J.
Applicants: VICKERS INCORPORATED
Application year: 1990
Main classification: F04C15
IPC codes: F04C14, F04B49, F04C2, F03C2