Rotary hydraulic pressure amplifier system

Abstract

A hydraulic actuator system comprising a hydraulic source, load and fluid return, a rotary pressure amplifier comprising a fluid control journal, a cylinder block with a plurality of pistons, and an offset displacement drive in engagement with the pistons, an inlet port of the journal connected to the source, an outlet port of the journal connected to the load, an exhaust port of the journal connected to the return, a fluid exchange area of the intake port being greater than a fluid exchange area of each of the discharge port and the exhaust port, the source configured to drive rotation of the cylinder block via the inlet port, and the amplifier configured to divide fluid flow from the inlet port between the outlet and exhaust ports and to discharge fluid from the outlet port at a discharge pressure greater than an intake pressure at the inlet port.

Description

ROTARY HYDRAULIC PRESSURE AMPLIFIER SYSTEMTECHNICAL FIELD

[0001] The present invention relates generally to the field of hydraulic actuator systems, and more particularly to an improved rotary hydraulic pressure amplifier system.BACKGROUND ART

[0002] Rotary and axial hydraulic actuation systems that provide actuation in at least one motion axis are used in a number of industries. Such systems can directly or indirectly drive linear or rotary actuators and may include drive control and power electronics to control and monitor operation of the actuator.BRIEF SUMMARY

[0003] With parenthetical reference to corresponding parts, portions or surfaces of the disclosed embodiment, merely for the purposes of illustration and not by way of limitation, a hydraulic actuator system (15. 115) is provided comprising: a hydraulic pressure source (20. 120) operatively configured to provide a hydraulic fluid at an operating pressure; a hydraulic pressure load (40, 100, 140) having an operating demand pressure, a hydraulic fluid return (16); a rotary pressure amplifier (70) comprising a fluid control journal (71). a cylinder block (80) adapted to rotate relative to the fluid control journal about a block axis (88), and a displacement drive (75) having a displacement axis (78) offset from the block axis; the cylinder block comprising a plurality of pistons (85); each of the pistons of the cylinder block operatively configured to reciprocate in a piston chamber (82, 83. 84) of the cylinder block relative to the fluid control journal with rotation of the cylinder block about the block axis and having a drive end (87) in bearing engagement with the displacement drive; the fluid control journal comprising an inlet port (72) having a per-revolution intake exchange area (72a), an outlet port (73) having a per-revolution discharge exchange area (73a), and an exhaust port (74) having a per-revolution exhaust exchange area (74a); the inlet port operatively connected to the hydraulic pressure source; the outlet port operatively connected to the hydraulic pressure load; the exhaust port operatively connected to the hydraulic fluid return; the per revolution intake exchange area being greater than the per-revolution discharge exchange area; the per revolution intake exchange area being greater than the per- revolution exhaust exchange area; the hydraulic pressure source operatively configured to drive rotation of the cylinder block of the rotary pressure amplifier about the block axis via115157655 1hydraulic fluid provided from the hydraulic pressure source to the inlet port of the rotary pressure amplifier; and the rotary pressure amplifier operatively configured to divide flow from the hydraulic pressure source at an intake pressure at the inlet port between the outlet port and the exhaust port and to discharge the hydraulic fluid from the outlet port at a discharge pressure greater than or equal to the intake pressure.

[0004] The per revolution discharge exchange area may be greater than the per-revolution exhaust exchange area. The cylinder block may be adapted to rotate relative to the fluid control journal about the block axis in only one direction.

[0005] The hydraulic pressure source may comprise a positive displacement pump (20). The positive displacement pump may be selected from a group consisting of a radial piston pump, an axial piston pump, a vane pump, and a gear pump. The positive displacement pump may comprise a variable displacement pump driven by an aircraft engine. The positive displacement pump may comprise an electric drive motor and a batleiy supplying current to the electric drive motor.

[0006] The hydraulic pressure load may comprise an actuator (100). The demand pressure may comprise a differential pressure across the actuator. The hydraulic pressure load may further comprise an actuator control module (30, 40, 140). The actuator control module may comprise an actuator control valve (40) between the discharge port and the actuator configured to meter flow between the discharge port and the actuator. The actuator control valve may be connected to the hydraulic pressure source. The hydraulic pressure source may be connected to the actuator control valve independently of the rotary pressure amplifier by a direct supply fluid connection (21) and the actuator control valve may configured to meter flow between the hydraulic pressure source and the actuator. The actuator control module may comprise a controller (30) connected to the actuator control valve. The system may comprise a pressure sensor (31) configured to sense an input pressure to the actuator control valve and connected to the controller. The actuator control valve may comprise an electro-hydraulic servovalve. The electro-hydraulic servovalve may comprise an infinite position, four way, spool valve having an open metering state and a closed neutral state.

[0007] The actuator may comprise a linear hydraulic actuator (100) or a rotary hydraulic actuator. The hydraulic actuator may comprise a linear hydraulic actuator having a first chamber (105), a second chamber (106) and a piston (107) separating the first and second chambers. The hydraulic actuator may comprise a cylinder (104) having a first end wall, the piston may be disposed in the cylinder for sealed sliding movement therein, the piston may215157655 1comprise a first actuator rod (111) having a portion sealingly penetrating the first end wall, the cylinder may have a second end wall, and the piston may comprise a second actuator rod (108) having a portion sealingly penetrating the second end wall.

[0008] The fluid control journal may comprise a port plate (71); the displacement drive may comprise a cam plate (75) orientated about the displacement axis; the displacement axis may be offset from the block axis by a cam angle (79); each of the piston chambers of the cylinder block may extend axially; and each of the pistons of the cylinder block may be operatively configured to reciprocate axially. The cylinder block may be adapted to rotate relative to the cam plate and the cam plate may be fixed relative to the port plate at a fixed cam angle. The fluid control journal may comprise a central control journal; the displacement drive may comprise a stroke ring orientated about the displacement axis; the displacement axis may be offset from the block axis an eccentric distance; each of the piston chambers of the cylinder block may extend radially; and each of the pistons of the cylinder block may be operatively configured to reciprocate radially.

[0009] The rotary pressure amplifier may have a pressure increase ratio between the intake pressure at the inlet port and the discharge pressure at the outlet port that is substantially proportional to an exchange ratio between the per revolution intake exchange area of the inlet port and the per-revolution discharge exchange area of the outlet port.

[0010] The hydraulic pressure source may be connected to the hydraulic pressure load independently of the rotary pressure amplifier by a direct supply fluid connection (21) and the system may comprise a bypass valve (60) in the direct supply fluid connection between the hydraulic pressure source and the hydraulic pressure load. The system may comprise an exhaust control valve (50, 150, 157) between the exhaust port and the hydraulic fluid return configured to meter flow between the exhaust port and the hydraulic fluid return. The exhaust control valve may comprise a flow restriction (157) between the exhaust port and the hydraulic fluid return. The flow7restriction may comprise a flow7rate limiting orifice (157) in a fluid connection (154) between the exhaust port and the hydraulic fluid return. The exhaust control valve may comprise a direct acting valve (150) or a pilot operated logic valve. The exhaust control valve may comprise a load sensing valve (50) configured to sense the operating demand pressure and to open the exhaust port connection to the hydraulic fluid return if the demand pressure is equal to or exceeds a threshold and to close the exhaust port connection to the hydraulic fluid return if the demand pressure is below the threshold. The load sensing valve may compnse an infinite position, three way, pilot activated spool valve315157655 1(50) having an open metering state and a closed neutral state. The demand pressure may comprise a differential pressure across an actuator (100).BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings are incorporated herein as part of the specification. The drawings described herein illustrate embodiments of the presently disclosed subject matter and are illustrative of selected principles and teachings of the present disclosure. However, the drawings do not illustrate all possible implementations of the presently disclosed subject matter and are not intended to limit the scope of the present disclosure in any way.

[0012] FIG. 1 is a schematic view of a first embodiment of an improved rotary hydraulic pressure amplifier system in a steady state.

[0013] FIG. 2 is a schematic view of the improved rotary hydraulic pressure amplifier system shown in FIG. 1 in an inactive amplification state.

[0014] FIG. 3 is a schematic view of the improved rotary hydraulic pressure amplifier system shown in FIG. 1 in a first active amplification state.

[0015] FIG. 4 is a schematic view of the improved rotary hydraulic pressure amplifier system shown in FIG. 1 in a second active amplification state.

[0016] FIG. 5 is a side perspective view of the pressure amplifier shown in shown in FIG. 1.

[0017] FIG. 6 is a partial exploded view of the pressure amplifier shown in FIG. 5.

[0018] FIG. 7 is a schematic view of a second embodiment of an improved rotary hydraulic pressure amplifier system.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] At the outset, it should be clearly understood that like reference numerals are intended to identify the same structural elements, portions, or surfaces consistently throughout the several drawing figures, as such elements, portions or surfaces may be further described or explained by the entire written specification, of which this detailed description is an integral part. Unless otherwise indicated, the drawings are intended to be read (e.g., crosshatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this invention. As used in the following description, the terms "horizontal", "vertical", "left", "right", "up" and "down", as well as adjectival and adverbial derivatives thereof (e.g., "horizontally", "rightwardly", "upwardly", etc.), simply refer to the orientation of the illustrated structure as the particular415157655 1drawing figure faces the reader. Similarly, the terms "inwardly" and "outwardly" generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.

[0020] It is to be understood that the specific assemblies and systems illustrated in the attached drawings and described in the following specification are simply exemplary embodiments of the inventive concepts defined herein. Hence, specific dimensions, directions, or other physical characteristics relating to the embodiments disclosed are not to be considered as limiting, unless expressly stated otherwise. Also, although they may not be, like elements in various embodiments described herein may be commonly referred to with like reference numerals within this section of the application.

[0021] It is to be appreciated that the present teaching is by way of example only, not by limitation. The concepts herein are not limited to use or application with a specific system or method. Thus, although the instrumentalities described herein are for the convenience of explanation, shown and described with respect to exemplary' embodiments, it will be appreciated that the principles herein may be applied equally in other types of systems and methods involving actuators.

[0022] Where they are used herein, the terms “first,” “second,” and so forth, do not necessarily denote any ordinal, sequential or priority relation, but are simply used to distinguish one element or set of elements more clearly from another element or set of elements, unless specified otherwise.

[0023] An improved hydraulic actuator system is provided, a first embodiment of which is generally indicated at 15. As shown in FIG. 1, system 15 is adapted to actuate object 17 and generally includes hydraulic pump 20, actuator 100 hydraulically connected to pump 20, hydraulic fluid return 16, main control valve 40, load sensing control valve 50, bypass valve 60, rotary' hydraulic pressure amplifier 70, and controller 30.

[0024] In this embodiment, pump 20 comprises a positive displacement pump. In a representative embodiment, pump 20 is a radial piston pump driven by an electric motor. In alternative embodiments, pump 20 may be an axial piston pump, a vane pump, or a gear pump driven by an electric motor. In a representative embodiment, pump 20 is the system pump for a flight control system of an aircraft and object 17 is a flight control surface of the aircraft. In such representative embodiment, pump 20 may be a pressure compensated, variable displacement, engine driven pump.

[0025] As shown in FIGS 5 and 6. rotary hydraulic pressure amplifier 70 generally comprises port plate 71, rotor cylinder block 80 adapted to rotate relative to port plate 71515157655 1about block axis 88, and swash or cam plate 75 having displacement axis 78 offset from block axis 88 by angular displacement cam angle 79.

[0026] As shown in FIG. 5, upper port plate 71 has three primary ports that extend from the outer annular end face of port plate 71 through to the inner annular end face of port plate71, namely inlet drive port 72, discharge port 73, and exhaust port 74. The outside of inlet port 72 is connected to pump 20 via fluid lines 21 and 22 and is configured to provide driving pressure from pump 20 to rotor 80. The outside of discharge port 73 is connected to actuator control valve 40 via fluid lines 23 and 45. The outside of exhaust port 74 is connected to exhaust control valve 50 via fluid line 54. As shown in FIG. 6, the inner end face of port plate 71 is positioned axially adjacent the upper end face of rotor cylinder block 80 and ports72, 73 and 74 each have specially configured arcuate fluid exchange areas 72a, 73a and 74a, respectively, in fluid communication with opposed cylinders 82, 83, and 84 of rotor 80. As shown, drive port 72 has the longest arc length about axis 88 at the interface with rotor 80 to provide the greatest per-revolution intake exchange area 72a with rotor 80. In this embodiment, exhaust port 74 has the shortest arc length about axis 88 at the interface with rotor 80 to provide the lowest per-revolution intake exchange area 72a. And discharge port 73 has an arc length about axis 88 at the interface with rotor 80 that is less than the arc length of port 72 and greater than the arc length of port 74. Thus, inlet port 72 has a per-revolution intake exchange area 72a that is greater than the per-revolution discharge exchange area 73a of discharge port 73. Also, the per-revolution intake exchange area 72a of inlet port 72 is also greater than the per-revolution exhaust exchange area 74a of exhaust port 74. In this embodiment, the per-revolution discharge exchange area 73a of discharge port 73 is greater than the per-revolution exhaust exchange area 74a of exhaust port 74. In an alternative embodiment, exhaust port 74 may not have the shortest arc length about axis 88 at the interface with rotor 80 and the ratio of the port arc lengths may be matched to the actuator application.

[0027] As shown, rotor 80 comprises a plurality of axially extending piston chambers 82, 83 and 84 orientated circumferentially about axis 88 and having upper open ends in rotational fluid communication with the inner openings of ports 72, 73 and 74. Rotor 80 comprises a plurality of axially extending pistons 85 operatively configured to reciprocate in piston chambers 82, 83, 84 of rotor 80 relative to port plate 71 with rotation of rotor 80 about rotor axis 88 and having lower drive ends 87 in bearing engagement with cam plate 75 and upper piston ends rotationally aligned about axis 88 with inner arcuate exchange openings 72a, 73a and 74a of ports 72, 73 and 74. As shown, in neutral angular alignment about axis 88, piston615157655 1chambers 82 align with inlet exchange opening 72a of port 72, piston chambers 83 align with discharge exchange opening 73a of port 73, and piston chamber 84 aligns with exhaust exchange opening 74a of port 74, such that in this embodiment the number of inlet driving piston chambers and pistons 82 is greater than the number of discharging piston chambers and pistons 83, and such that the number of discharging piston chambers and pistons 83 is greater than the number of exhausting piston chambers and pistons 84. However, the piston ratios may be varied as a discrete quantity of pistons communicate with the port plate. For example, and without limitation, five pistons may be connected to supply, two pistons to discharge, and two pistons to exhaust.

[0028] As shown, lower cam plate 75 has an upper cam face that is orientated on a plane that is not perpendicular to rotor axis 88. In particular, cam plate 75 is orientated about cam axis 78 and cam axis 78 is angularly offset from block axis 88 by cam angle 79. In this embodiment, cam plate 75 does not rotate with rotation of rotor 80 and is fixed relative to port plate 71 at a fixed cam angle that is not variable. Piston ends 87 bear against the upper titled or angled cam face of cam plate 75 such that pistons 85 reciprocate in chambers 82, 83 and 84 with rotation of rotor 80 about axis 88 relative to cam plate 75. In this fixed cam embodiment, the interface between piston ends 87 of pistons 85 and cam plate 75 comprises inline-axial piston shoe assemblies. However, alternatively the cam plate may rotate and the interface may comprise a shoeless configuration depending on desired application, with a shoeless piston configuration typically having lower leakage but a larger envelope and a greater weight because of the cam bearing and a shoed piston assembly configuration typically being smaller and lighter but less efficient because of the additional leakage through the shoes.

[0029] Rotation of rotor 80 about axis 88 relative to cam plate 75 is entirely hydraulically driven by pump 20 and fluid pressure acting on the upper piston ends of pistons 85 in chambers 82 when aligned with interface 72a of inlet port 72. Such pressure drives pistons 85 in chambers 82 down against the inclined cam face of cam plate 75. The axial hydraulic force of pistons 85 in chambers 82 acting against fixed cam plate 75 produces a torque acting on rotor 80 about axis 88 due to tilt angle 79a of cam plate 75. When exhaust port 74 is open to return, rotor 80 may thereby be driven to rotate about axis 88, which in turn drives pistons 85 in chambers 83 to discharge fluid from discharge port 73 at a discharge pressure and drives piston 85 in exhaust chamber 84 to exhaust fluid from exhaust port 74. No separate mechanical connection or mechanism, such as a motor, drives rotation of rotor 80 about axis 88 and rotation of rotor 80 about axis 88 is driven solely by pump 20 and the configuration of715157655 1pressure amplifier 70. Accordingly, pressure amplifier 70 has both a hydraulic input and a hydraulic output. In this embodiment, rotor 80 is configured to rotate in only one direction about axis 88 with fluid flow through pressure amplifier 70 being unidirectional. Alternatively, however, rotor 80 may be configured to counter-rotate if the discharge pressure exceeds an upper threshold to provide a pressure relieving function.

[0030] Accordingly, port plate 71 and rotor 80 effectively provide a three-port rotating group which acts as flow divider that amplifies pressure at discharge port 72 relative to the intake pressure at inlet port 72. The per revolution torque produced by the greater quantity of rotating group pistons 85 in chambers 82 connected to inlet driving port 72 is countered by the fewer quantity of pistons 85 in chambers 83 connected to discharging port 73. This amplifies the discharge pressure at discharge port 73 relative to the intake drive pressure at inlet port 72, with the pressure increase ratio from inlet port 72 to outlet port 73 being proportional to the port slot arc lengths and interface areas 72a and 73a of inlet port 72 and outlet port 73, respectively. Exhaust port 74 exhausts the fluid not provided to discharge port 73 from pressure amplifier 70. Pressure amplifier 70 thereby employs a three-port rotating group to amplify pressure within hydraulic circuit 15 without mechanical input. The single three-port rotating group uses the pressure from pump 20 to generate torque within the rotating group, which gets amplified because of the reduction in output flow in the three-port rotating group. The flow splitting function of the three-port configuration reduces the output flow but increases the output pressure. While some of the input hydraulic power is consumed as losses within amplifier 70, external mechanical input is not required. As shown in FIG. 1, in this embodiment pressure amplifier 70 includes fluid leakage port 34 and fluid leakage relief conduit 35 back to tank or return 16.

[0031] While in this embodiment pressure amplifier has an inline-axial piston configuration, a radial piston configuration or bent-axis piston configuration may be used as alternatives. For example, in an alternative radial piston configuration, port plate 71 is replaced with a central control journal, cam plate 75 is replaced with a stroke ring orientated about a stroke axis offset from the cylinder block axis an eccentric distance, and each of the piston chambers 82, 83 and 84 of the cylinder block 80 extend radially and each of the pistons 85 of the cylinder block 80 are operatively configured to reciprocate radially. Thus, the pistons are arranged radially in the rotating cylinder block, rather than axially, and have ends held in contact with the stroke ring. When the cylinder block is driven to rotate about the block axis by fluid pressure from pump 20, the pistons execute a radial stroking motion815157655 1due to the eccentricity of the stroke ring and the control journal includes the specially configured inlet port, discharge port and exhaust port.

[0032] As shown, in this embodiment, actuator 100 comprises a hydraulic piston assembly having piston 107 slidably disposed within cylindrical housing 104 such that piston107 may be driven linearly in two directions relative to housing 104. In this embodiment, rod108 is mounted to one side of piston 107 for movement with piston 107 and sealably penetrates the lower end wall of housing 104. Rod 111 is mounted to the other side of piston 107 for movement with piston 107 and sealably penetrates the upper end wall of housing 104. Piston 107 is slidably disposed within cylinder 104, and sealingly separates upper chamber 105 from lower chamber 106. In this embodiment, the upwardly-facing annular end surface of piston 107 faces into upper chamber 105 and the downwardly -facing annular end surface of piston 107 faces into lower chamber 106, creating an equal piston area configuration. Upper chamber 105 has fluid port 109 and lower chamber 106 has fluid port 110. Thus, hydraulic actuator 100 comprises chamber 105, chamber 106, and piston 107 separating the first and second chambers 106 and 106 such that, as the position of valve 40 changes, a differential pressure is produced between chamber 105 and chamber 106. This differential pressure causes hydraulic actuator 100 to drive object 17. Hydraulic actuator 100 may include a position sensor configured to sense the position of piston 107 or rod 108. Also, various linkages may be provided between rod 108 and driven object 17. While an equal piston area configuration is shown and described, an unequal piston area configuration may be used as an alternative. While in this embodiment actuator 100 is shown as a linear hydraulic actuator, a rotary hydraulic actuator that imparts a rotary' output may be used as an alternative.

[0033] In this embodiment, controller 30 receives valve commands and feedback from sensors in system 15 and controls valve 40 accordingly. For example, pressure signals from pressure transducer 31 and position signals from position transducers for actuator 100 may be fed back to controller 30. Controller 30, control valve 40, pump 20 and pressure amplifier 70 control the speed and force of piston 107 and in turn rod 108 by changing the flow and differential pressure acting on piston 107 in cylinder 104. This is accomplished by looking at the feedback of the actuator position sensor and then closing the control loop by adjusting control valve 40 accordingly. While in this embodiment the position sensor is a LVDT, other position sensor may be used such as without limitation encoders, hall position sensors, potentiometers, and resolvers. In this embodiment, pressure sensor 31 is a pressure915157655 1transducer in line 45 and is configured to sense pressure in pressure rail 45 and provides a pressure input signal to controller 30.

[0034] In this embodiment, control valve 40 is an electrohydraulic servovalve that controls the flow direction of the pressurized fluid from pump 20 and pressure amplifier 70 that is sent to actuator 100 and the hydraulic pressure differential on piston 107 of actuator 100. In this embodiment, control valve 40 is a single stage servovalve having a torque motor that positions a spool valve in response to an input signal from controller 30. Servovalve 40 receives pressurized hydraulic fluid from pressure line 45 and transfers the fluid to either of ports 109 and 110 of hydraulic cylinder 104 in a controlled manner and based on sensor feedback and valve commands. In this embodiment, control valve 40 is a four- way valve controlled by controller 30. Valve 40 is configured with a first port connected to chamber 105 via line 113 and port 109, a second port connected to chamber 106 via line 1 14 and port 110, a third port connected to pump 20 and discharge port 73 of pressure amplifier 70 via line 45, and a fourth port connected to tank or return 16 via line 46. Thus, one side of control valve 40 selectively communicates with chamber 105 via port 109 and fluid line 113 and selectively communicates with chamber 106 via port 110 and fluid line 114. The opposite side of valve 40 communicates with pump 20 and discharge port 73 of pressure amplifier 70 via fluid line 45 and communicates with tank or return 16 via fluid line 46. While in this embodiment control valve 40 is shown as a single stage four way servovalve, alternative types of control valves may be used, include without limitation dual stage servovalves, electro-hydraulic servovalves, and direct control valves such as solenoid valves.

[0035] As shown in FIG. 1, valve 40 may be controlled by controller 30 to block flow7between both chambers 105 and 106 of actuator 100 and pressure rail 45 and return rail 46 in a closed state. Valve 40 may be controlled by controller 30 to meter fluid flow from pressure rail 45 to chamber 105 and from chamber 106 to return 16 in a first state, as shown in FIGS. 2 and 3. Valve 40 may be controlled by controller 30 to meter fluid flow from pressure rail 45 to chamber 106 and from chamber 105 to return 16 in a second state, as shown in FIG. 4. Piston 107 will extend rod 108 when Pl is greater than P2 and fluid is drawn into chamber 105 through fluid port 109 from line 113 and out from chamber 106 through fluid port 110 and into line 114 to return 16, as shown in FIGS. 2 and 3. Piston 107 will retract rod 108 when P2 is greater than Pl and fluid is drawn into chamber 106 through fluid port 110 from line 114 and out from chamber 105 through fluid port 109 and into line 113 to return 16, as shown in FIG. 4.1015157655 1

[0036] In this embodiment, system 15 includes bypass valve 60 in fluid line 45 between pump 20 and main control valve 40. In this embodiment, bypass valve 60 is a one-way check valve that will block flow from control line 45 on one side of check valve 60 to supply line 21 on the other side of check valve 60 when pressure in line 45 is greater than pressure in supply line 21, but will allow flow directly from supply line 21 to control line 45, thereby- bypassing pressure amplifier 70, when the supply pressure in supply line 21 is greater than the demand pressure in control line 45. Thus, when pump 20 is able to meet the pressure demand for operating actuator 100, fluid is provided to control valve 40 and actuator 100 directly from pump 20 through valve 60 and fluid line 45, bypassing pressure amplifier 70. However, when pump 20 is not able to meet the pressure demand for operating actuator 100 directly via valve 60, and valve 60 closes, fluid is pumped from pump 20 to inlet port 72 of pressure amplifier 70 via amplifier line 22, bypassing check valve 60 via pressure amplifier 70. Thus, check valve 60 will seat when actuator 100 requires pressure greater than the operating pressure provided by pump 20, which thereby allows the pressure to be increased by pressure amplifier 70. Incorporating check valve 60 in parallel with pressure amplifier 70 allows fluid flow from pump 20 to bypass pressure amplifier 70 and be provided to control valve 40 and actuator 100 without amplification when amplification is not needed. Because the pressure losses through check valve 60 are much lower than the pressure losses within pressure amplifier 70, such bypass of pressure amplifier 70 increases the operating efficiency of system 15 when actuator 100 requires lower pressure. While in this embodiment valve 60 is a passive valve in which the operational state of open or closed is determined by the fluid the valve controls, alternatively the valve could be an active valve that employs an external actuation force to stay open or close.

[0037] In this embodiment, load sensing valve 50 is a three way, pilot-activated, spool valve that controls the pressurized fluid from exhaust port 74 of pressure amplifier 70 that is sent to return 16 based on the hydraulic pressure differential on piston 107 of actuator 100. As shown in FIG. 1, spool valve 50 is in line 54 between exhaust port 74 of pressure amplifier 70 and return 16 and comprises a spool slidably disposed within a housing such that the spool translates relative to the housing between a closed state blocking the ports to exhaust port 74 and return 16 and two open states connecting the ports to exhaust port 74 to return 16. Valve 50 is configured with a first port connected to exhaust port 74 of pressure amplifier 70 via line 54, a second port connected to return 16 via line 55, and a third port connected to return 16 via line 55. Thus, one side of control valve 50 selectively communicates with exhaust port 74 of pressure amplifier 70 via fluid line 54. The opposite1115157655 1side of valve 50 communicates with tank or return 16 via fluid line 55. As shown in FIGS. 1- 4, port 109 of actuator 100 is connected to pilot input port 51 of spool valve 50 via line 56 and port 110 of actuator 100 is connected to pilot input port 52 of spool valve 50 via line 57. When pressure Pl of chamber 105 of actuator 100 exceeds pressure P2 of chamber 106 of actuator 100 above a given threshold differential pressure limit (AP limit), based on the springs acting on the ends of the spool of valve 50, the spool of valve 50 is actuated to the right by pressure at port 51 to a first open state connecting exhaust port 74 of pressure amplifier 70 to return 16, thereby activating pressure amplifier 70, as shown in FIG. 3. When pressure P2 of chamber 106 of actuator 100 exceeds pressure Pl of chamber 105 of actuator 100 above the given threshold differential pressure limit (AP limit), the spool of valve 50 is actuated to the left by pressure at port 52 to a second open state connecting exhaust port 74 of pressure amplifier to return 16, thereby also activating pressure amplifier 70, as shown in FIG. 4. When the pressure differential between pressure Pl of chamber 105 of actuator 100 and pressure P2 of chamber 106 of actuator 100 does not exceed the given threshold differential pressure limit (AP limit), the spool of valve 50 returns to the closed state blocking the fluid connection between exhaust port 74 of pressure amplifier 70 and return 16, thereby deactivating pressure amplifier 70, as shown in FIGS. 1 and 2. Without control valve 50, fluid would always be discharged from exhaust port 74 without regard to the pressure required at discharge port 73, which could result in considerable operational inefficiencies. So hydraulic pilot lines 56 and 57 from actuator 100 thereby operate on the spool of valve 50. which initiates operation of pressure amplifier 70 only when the differential pressure demand exceeds a threshold. Blocking flow from exhaust port 74 to return 16 causes the other ports 72 and 73 of pressure amplifier 70 to approach supply pressure and disables the pressure amplification function of pressure amplifier 70 because of torque equalization within the rotating group of pressure amplifier 70. Accordingly, control valve 50 in exhaust port flow passage 54 allows the function of pressure amplifier 70 to be enabled or disabled. Pressure amplification can thereby be employed only during portions of the duty cycle when beneficial, which optimizes efficiency and minimizes high-pressure fatigue cycles. Thus, valve 50 provides a differential feedback system that is operatively configured to regulate pressure amplifier 70 as a function of the relative pressure of fluid in chambers 105 and 106 of actuator 100 and the given threshold differential pressure limit. Using loading sensing control valve 50 also eliminates the need for active control and associated confirmation of functionality. While in this embodiment control valve 50 is shown as a three way pilot activated spool valve, alternative types of control valves may be used, include without1215157655 1limitation dual stage servovalves, electro-hydraulic servovalves, direct control valves such as solenoid valves, and pilot operated logic valves.

[0038] Referring now to FIG. 7, a second embodiment 115 of an improved hydraulic actuator system is shown. As shown, system 115 is adapted to provide hydraulic pressure to control module 140 and generally includes hydraulic fluid flow supply 120, control module 140 connected to fluid supply 120, flow restriction 157, exhaust control valve 150, bypass valve 60. and rotary hydraulic pressure amplifier 70.

[0039] In this embodiment, hydraulic fluid supply 120 may be an aircraft hydraulic fluid system. Alternatively, other fluid media besides hydraulic fluid may be used. For example, the fluid media may comprise jet fuel from an aircraft tank for example.

[0040] In this embodiment, bypass valve 60, transducer 31, return 16 and pressure amplifier 70 are of the same configuration as in system 15. However, in this embodiment, flow restriction 157 and control valve 150 are provided between exhaust port 74 of pressure amplifier 70 and return 16.

[0041] Flow restriction 157 in flow path 154 between exhaust port 74 and return 16 provides a speed limiting function. The orifice pressure loss increases with flow and is applied to the pistons 84 connected with port interface 74a of exhaust port 74. The pressure applied to the pistons generates a torque that is summed with the torque from the pistons 83 connected with port interface 73a of discharge port 73 and opposes motion of the rotating group.

[0042] In this embodiment, control valve 150 is a direct acting solenoid valve, although alternatives may be used including without limitation a pilot operated logic valve piloted by a solenoid valve or a hydraulic signal from control module 140. In addition, flow restriction 157 may be integrated into control valve 150. Blocking flow from exhaust port 74 to return 16 causes the other ports 72 and 73 of pressure amplifier 70 to approach supply pressure and disables the pressure amplification function of pressure amplifier 70 because of torque equalization within the rotating group of pressure amplifier 70. Accordingly, control valve 150 enables pressure amplification to be employed only during portions of the duty cycle when beneficial, which optimizes efficiency and minimizes high-pressure fatigue cycles. In this embodiment, pressure transducer 31 is provided to confirm proper functioning of pressure amplifier 70.

[0043] In this embodiment control module 140 comprises a directional control valve and controller. However, other fluid metering valves may be used as alternatives, including1315157655 1without limitation direct acting servovalves, single stage servovalves, dual stage servovalves, and electro-hydraulic servovalves.

[0044] Hydraulic actuator systems 15 and 115 provide a number of benefits. They provide an increase to the operating pressure available to a servo actuator as a function of the load applied to the actuator, which reduces the weight, envelope and peak hydraulic power consumption of the actuator when sized by peak operating load. They may be used to augment the capability of linear actuators (hydraulic cylinders) and rotary actuators (hydraulic motors) for military aircraft, civilian aircraft, and industrial applications. They reduce the quantity of components and are more reliable. They can operate in a closed system with self-contained hydraulic supply and return porting and limited fluid contamination and leakage concerns.

[0045] Many changes and modifications may be made. Therefore, while embodiments of an improved hydraulic actuator system have been shown and described, and a number of alternatives discussed, persons skilled in this art will readily appreciate that various additional changes and modifications may be made without departing from the scope of the invention, as defined, and differentiated by the following claims.1415157655 1

Claims

CLAIMSWhat is claimed is:

1. A hydraulic actuator system comprising: a hydraulic pressure source operatively configured to provide a hydraulic fluid at an operating pressure; a hydraulic pressure load having an operating demand pressure; a hydraulic fluid return; a rotary pressure amplifier comprising a fluid control journal, a cylinder block adapted to rotate relative to said fluid control journal about a block axis, and a displacement drive having a displacement axis offset from said block axis; said cylinder block comprising a plurality of pistons; each of said pistons of said cylinder block operatively configured to reciprocate in a piston chamber of said cylinder block relative to said fluid control journal with rotation of said cylinder block about said block axis and having a drive end in bearing engagement with said displacement drive; said fluid control j oumal comprising an inlet port having a per-revolution intake exchange area, an outlet port having a per-revolution discharge exchange area, and an exhaust port having a per-revolution exhaust exchange area; said inlet port operatively connected to said hydraulic pressure source; said outlet port operatively connected to said hydraulic pressure load; said exhaust port operatively connected to said hydraulic fluid return; said per revolution intake exchange area being greater than said per-revolution discharge exchange area; said per revolution intake exchange area being greater than said per-revolution exhaust exchange area; said hydraulic pressure source operatively configured to drive rotation of said cylinder block of said rotary’ pressure amplifier about said block axis via hydraulic fluid provided from said hydraulic pressure source to said inlet port of said rotary pressure amplifier; and said rotary pressure amplifier operatively configured to divide flow from said hydraulic pressure source at an intake pressure at said inlet port between said outlet port and said exhaust port and to discharge said hydraulic fluid from said outlet port at a discharge pressure greater than or equal to said intake pressure.1515157655 12. The hydraulic actuator system set forth in claim 1. wherein said per revolution discharge exchange area is greater than said per-revolution exhaust exchange area.

3. The hydraulic actuator system set forth in claim 1, wherein said cylinder block is adapted to rotate relative to said fluid control journal about said block axis in only one direction.

4. The hydraulic actuator system set forth in claim 1, wherein said hydraulic pressure source comprises a positive displacement pump.

5. The hydraulic actuator system set forth in claim 4, wherein said positive displacement pump is selected from a group consisting of a radial piston pump, an axial piston pump, a vane pump, and a gear pump.

6. The hydraulic actuator system set forth in claim 4, wherein said positive displacement pump comprises an electric drive motor and a battery supplying current to said electric drive motor or said positive displacement pump comprises a variable displacement pump driven by an aircraft engine.

7. The hydraulic actuator system set forth in claim 1, wherein said hydraulic pressure load comprises an actuator.

8. The hydraulic actuator system set forth in claim 7, wherein said demand pressure comprises a differential pressure across said actuator.

9. The hydraulic actuator system set forth in claim 7. wherein said hydraulic pressure load comprises an actuator control module.

10. The hydraulic actuator system set forth in claim 9, wherein said actuator control module comprises an actuator control valve between said discharge port and said actuator configured to meter flow between said discharge port and said actuator.

11. The hydraulic actuator system set forth in claim 10, wherein said actuator control valve is connected to said hydraulic pressure source.

12. The hydraulic actuator system set forth in claim 11, wherein said hydraulic pressure source is connected to said actuator control valve independently of said rotary pressure1615157655 1amplifier by a direct supply fluid connection and said actuator control valve is configured to meter flow between said hydraulic pressure source and said actuator.

13. The hydraulic actuator system set forth in claim 10, wherein said actuator control module comprises a controller connected to said actuator control valve.

14. The hydraulic actuator system set forth in claim 13, comprising a pressure sensor configured to sense an input pressure to said actuator control valve and connected to said controller.

15. The hydraulic actuator system set forth in claim 10, wherein said actuator control valve comprises an electro-hydraulic servovalve.

16. The hydraulic actuator system set forth in claim 15, wherein said electro-hydraulic servovalve comprises an infinite position, four way, spool valve having at least one open metering state and at least one closed neutral state.

17. The hydraulic actuator system set forth in claim 7. wherein said actuator comprises a linear hydraulic actuator or a rotary hydraulic actuator.

18. The hydraulic actuator system set forth in claim 17, wherein said hydraulic actuator comprises a linear hydraulic actuator having a first chamber, a second chamber and a piston separating said first and second chambers.

19. The hydraulic actuator system set forth in claim 18, wherein said hydraulic actuator comprises a cylinder having a first end wall, said piston is disposed in said cylinder for sealed sliding movement therein, said piston comprises a first actuator rod having a portion sealingly penetrating said first end wall, said cylinder has a second end wall, and said piston comprises a second actuator rod having a portion sealingly penetrating said second end wall.

20. The hydraulic actuator system set forth in claim 1. wherein: said fluid control j oumal comprises a port plate; said displacement drive comprises a cam plate orientated about said displacement axis; said displacement axis is offset from said block axis by a cam angle; and each of said piston chambers of said cylinder block extend axially and each of said pistons of said cylinder block are operatively configured to reciprocate axially.1715157655 121. The hydraulic actuator system set forth in claim 20, wherein said cylinder block is adapted to rotate relative to said cam plate and said cam plate is fixed relative to said port plate at a fixed cam angle.

22. The hydraulic actuator system set forth in claim 1. wherein: said fluid control journal comprises a central control journal; said displacement drive comprises a stroke ring orientated about said displacement axis; a displacement position between said displacement axis and said block axis comprises an eccentric position wherein said displacement axis is offset from said block axis an eccentric distance; and each of said piston chambers of said cylinder block extend radially and each of said pistons of said cylinder block are operatively configured to reciprocate radially.

23. The hydraulic actuator system set forth in claim 1. wherein said rotary pressure amplifier has a pressure increase ratio between said intake pressure at said inlet port and said discharge pressure at said outlet port that is substantially proportional to an exchange ratio between said per revolution intake exchange area of said inlet port and said per-revolution discharge exchange area of said outlet port.

24. The hydraulic actuator system set forth in claim 1, wherein said hydraulic pressure source is connected to said hydraulic pressure load independently of said rotary pressure amplifier by a direct supply fluid connection and comprising a unidirectional valve in said direct supply fluid connection between said hydraulic pressure source and said hydraulic pressure load.

25. The hydraulic actuator system set forth in claim 24, comprising an exhaust control valve between said exhaust port and said hydraulic fluid return configured to meter flow between said exhaust port and said hydraulic fluid return.

26. The hydraulic actuator system set forth in claim 25, wherein said exhaust control valve comprises a flow restriction between said exhaust port and said hydraulic fluid return.

27. The hydraulic actuator system set forth in claim 26, wherein said flow restriction comprises a flow rate limiting orifice in a fluid connection between said exhaust port and said hydraulic fluid return.1815157655 128. The hydraulic actuator system set forth in claim 25, wherein said exhaust control valve comprises a direct valve or a pilot operated logic valve.

29. The hydraulic actuator system set forth in claim 25, wherein said exhaust control valve comprises a load sensing valve configured to sense said operating demand pressure and to open said exhaust port connection to said hydraulic fluid return if said demand pressure is equal to or exceeds a threshold and to close said exhaust port connection to said hydraulic fluid return if said demand pressure is below said threshold.

30. The hydraulic actuator system set forth in claim 29, wherein said load sensing valve comprises an infinite position, three way, pilot activated spool valve having an open metering state and a closed neutral state.1915157655 1

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