US3655303A - Energy absorbing rotary piston pump - Google Patents

Abstract

An energy absorbing device, which is highly effective for use in an aircraft arresting gear, is provided by mounting a rotary pump having a pressure related characteristic within a container of fluid. The pump circulates the fluid from and back into the container whereby it absorbs energy in response to a mechanical input and transmits this energy to the fluid in the container in the form of heat. A highly effective form of this device utilizes a rotary piston-type pump having an axial input channel in its shaft connected to radial passageways extending through its cam disc and rotating piston. The fluid is discharged through pressure relief valves of the compressed air cushioned type. The rotary piston-type pump is particularly advantageous for such service because its rotor rotates slower than the input shaft, thus minimizing the mass of the pump to provide a given amount of energy absorption.

Description

1 e lilssste gtates Patent 1151 3,6553% Qotton 54 ENERGY SQHNG ROTY PISTON 3,452,723 7/1969 Keylwert ..l23/8.07 PUMP FOREIGN PATENTS OR APPLICATIONS [72] Inventor: Robert 13. Cotton, Media, Pa. 1,133,762 11/1956 France [73] Assignee: All American Industries, linc., Wilmington,

Del. Primary Examiner-Carlton R. Croyle Assistant Examiner-John J. Vrablik [22] Wed: 1970 AttorneyConnolly and Hutz [21] Appl. N0.: 84,825

[57] ABSTRACT Related Application Dam An energy absorbing device, which is highly effective for use [63] Continuation-impart of Ser. No. 756,035, Aug. 28, in an aircraft arresting gear, is provided by mounting a rotary 1968, Pat. No. 3,549,110.

pump having a pressure related characteristic within a container of fluid. The pump circulates the fluid from and back [52] U.S. Cl ..4l8/61, 418/188 into the n in r her by it absorbs energy in response to a [51] Int. Cl ..F0lc1/02, F04c 1/02, F040 15/02 mechanical input n r n mi his energy to the fl id in the 53 Field of Search ..418/60, 61, 183, 185, 186-188; container in the form of heat A highly effective form of this 123/833 3 5 device utilizes a rotary piston-type pump having an axial input channel in its shaft connected to radial passageways extending 56 R f C-ted throu h its cam disc and rotating piston. The fluid is I 1 e Memes disch rged through pressure relief valves of the compressed UNITED STATES PATENTS air cushioned type. The rotary piston-type pump is particularly advantageous for such service because its rotor rotates 3,l 15,871 12/1963 LllClf ..418/61 slower than the i p shaft, thus the mass of the 3,255,737 6/1966 Nallinger ..418/61 pump to provide a given amount ofenergy absorption. 3,340,853 9/1967 Link ..418/61 3,413,961 12/1968 Keylwert ..123/8.45 5 Claims, 21 Drawing Figures .40 O O 0.3 O 37 0 0 (46A 0 0 l 5 fl 0 102A A? 1270 54A I ma 944? O l A O O .543 [22 322 69 G 122 O 0 100B 0 29 O 125 4&8 7 1023 til .525 5.34,

0 Q25 0 66B 0 O o o .54 o

PATENTEDAFR 1 1 I972 SHEET 3 [1F 7 PATENTEDAPR 11 1972 3,655,303

SHEET 5 [1F 7 I ENERGY ABSORBING ROTARY PISTON PUMP CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of U.S. application Ser. No. 756,035, filed Aug. 28, 1968 now U.S. Pat. No. 3,549,110.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an energy absorbing device for aircraft arresting gear and a unique pump which is particularly useful therein.

2. Description of the Prior Art Various fluid-operated devices have been used for absorbing energy in aircraft arresting gear. Most of such energy absorbing devices develop torque as a function of velocity which enhances their energy-absorbing capacity. Their velocityresponsive nature, however, does not allow for sufficient torque control to obtain an efficient deceleration curve during the arrest, particularly for a wide range of airplane weights and airplane engaging velocities. Hydraulic pumps having pressure related characteristics have been proposed for such use, but no prexisting pump arrangements have had sufficient capacity to absorb the peak energy required to arrest modern high speed aircraft. See British Pat. No. 287,189 (1928).

SUMMARY This invention utilizes several novel features which are useful both independently and in combination. An efiicient energy absorbing device is provided by mounting a rugged rotary pump having a pressure related characteristic within the interior of a substantially large container of fluid. The fluid is circulated from the container through the pump and back into the container in response to rotation of the pump. This absorbs considerable mechanical input energy transmitted by the pump to the substantial body of fluid in the container in the form of heat. Recirculation of the fluid within the container makes it possible for a limited amount of fluid to absorb considerable energy.

A rotary piston pump is particularly effective for such service because of its simplicity and step down ratio between rotor and input shaft speeds. This minimizes the mass of the pump necessary to provide a given amount of energy absorption. Such a pump (which is also independently useful) advantageously includes pressure relief-type or program actuated outlet valves and an inlet flow system including a hollow cam shaft having radial port in the cam disc and triangular piston. Sealing means of variable effectiveness may be provided between the triangular rotary piston and the walls of the epitrochoidal housing within which it rotates to by-pass, minimize resistance of the pump at higher speeds of operation and to reduce the back pressure in the container required to prevent cavitation of the pump.

BRIEF DESCRIPTION OF THE DRAWINGS Novel features and advantages of the present invention will become apparent to one skilled in the art from a reading of the following description in conjunction with the accompanying drawings wherein similar reference characters refer to similar parts and in which:

FIG. 1 is a perspective view of one embodiment of this invention being used in an aircraft arresting gear;

FIG. 2 is a schematic diagram of the energy absorber shown in FIG. 1;

FIG. 3 is a bottom cross-sectional plan view taken through the energy absorber shown in FIGS. 1 and 2 and through FIG. 4 along the line 3-3;

FIG. 4 is a cross-sectional view taken through FIG. 3 along the line 4-4;

FIGS. SA-SE are schematic cross-sectional views taken through the housing of the energy absorber shown in FIGS. 2-4 illustrating the cycle of operation of the inlet and outlet valves;

FIG. 6 is a perspective view of edge and side sealing means for the rotary piston of the energy absorber shown in FIGS. 2-5;

FIGS. 7A and 7B are schematic diagrams showing operation of an optional form of sealing means for bypassing fluid during high speed operation;

FIG. 8 is a front elevational view of another embodiment of this invention illustrating a rotary device and its fluid control system;

FIG. 9 is a side elevational view of the embodiment described in FIG. 8;

FIG. 10 is a front elevational view shown in FIGS. 23-9;

FIG. 11 is a cross-sectional view taken through the rotary device along lines 11-11 of FIG. 10;

FIG. 12 is a schematic diagram illustrating the basic geometry of the rotary device; and

FIGS. l3A-I3D are schematic diagrams illustrating various positions of the pistons and crankshaft of the rotary device during its operational cycle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. I is shown an airplane 10 being arrested by aircraft arresting gear 12 engaging in hook 14 extending from below the tail of aircraft 10. Aircraft arresting gear 12, for example, includes a deck pendant or cable 16 extending across runway 18 on flight deck 20 of naval aircraft carrier 22. Each end of pendant 16 extends through sheave blocks 24A and B mounted on each side of runway 18 and connected to long lengths of payout line, such as steel cable 26, which extend over pulleys 28A and B, 30A and B and through deck apertures 32 A and B to below-deck linear storage and payout device 34. Device 34 is for example of the type utilizing steel cable as described in copending application for U.S. Pat. Ser. No. 632,289 filed Apr. 20, 1967, now U.S. Pat. No. 3,467,347, by this same inventor. Linear storage and payout device 34 may be of any effective type, such as a simple reel of nylon tape, for example as described in U.S. Pat. No. 3,172,625. The cable or nylon (which may be referred to as a linear payout element) and the storage device are mounted above and connected to energy absorber 37 of system 36.

FIGS. 2-4 show energy absorbing system 36 including rotary piston-type pump 38 mounted within a container 40 of a substantial amount of fluid, such as ethylene glycol and water.

Rotary piston-type pump 38 is an adaptation of the rotary piston engine commonly referred to as the Wankel engine. This engine is described in various publications including: The Way the Things Work published by Simon and Schuster, New York, Second Printing, Library of Congress Catalog Card No. 67-2792; Paper 886d, presented Aug. 1964 at the S.A.E. National West Coast Meeting, entitled The Curtiss-Wright Rotating Combustion Engines Today by Charles Jones, Wright Aeronautical Division, Curtiss-Wright Corp.; an article in the Apr. 1966 issue of Popular Science Magazine, pages 98-107 entitled The Engine Thats Giving Detroit Wankel Fever" by Devon Francis and U.S. Pat. No. 3,391,677.

Pump 38 as shown herein differs in many respects from the Wankel rotary piston engine but similar terminology is employed herein for similar features. Pump 38 may also be any rugged and dependable rotary pump having a pressure related characteristic, such as a gear or lobed pump. The rotary piston pump illustrated herein is particularly advantageous because of its relatively low mass relative to energy absorbing capability by virtue of the slower rotation of its rotor relative to input shaft speed for reasons later explained in detail.

Pump 38 includes triangular piston 42 rotating within housing 44 having an epitrochoidal cross section, presenting an oval-shape slightly constricted in the middle. A pair of outlet valves 46A and B discharge fluid during discharge phases of operation into container or tub 40. Fluid is introduced to pump 38 through: axial inlet channel 48 and cutout sector 50 in rotary cam 49 and through radial ports 52 in triangular of the rotary device piston 42. The space between triangular piston 42 and the inside of housing 44 is sealed by resilient wipers 54A, B and C of the type described on page I06 of the aforementioned Popular Science article. Wipers 54A, B and C are generally referred to as wipers 54.

Pressure accumulator system 56 is provided for energizing the retrieval of cables 26A and B and for tensioning pendant 16 after retrieval. System 56 includes pressure storage cylinder 58 with free piston 69 separating hydraulic fluid 62 from compressed air 64. The pressure supply to cylinder 58 is provided through pipe lines 66A and B connected to chamber 68A and 68B of pump housing 44. Lines 66A and 66B merge into a single pipe line 70 connected to pressure cylinder 58 through check valve 72.

Retrieve motor 74 is supplied through pipe 76 connected to pressure cylinder 58 through control valve 78. Retrieve motor 74 is connected to linear storage and payout device 34, for example through a sprocket and chain assembly 80. Since linear storage and payout system 34 might not be capable of withstanding the force of pendant tensioning, tensioning control device 82 is provided to bypass check valve 72. This permits pressure to be directed from cylinder 58 into pump chambers 68A and B in the reverse direction, thus applying a very slight reverse displacement to pump 38, which is on the output or capstan side of the linear storage and payout system. This permits the linear payout elements and runway pendant to be tensioned without unduly stressing the storage and payout system. This is particularly important in the cable storage and payout system described in the aforementioned copending patent application Ser. No. 632,289, filed Apr. 20, 1967, by this same inventor. Makeup fluid for pressure cylinder 58 is stored in gravity tank 84 and adequate pressure in the system may be verified through pressure gauge 86.

In FIGS. 3 and 4 are shown details of energy absorbing device 37. FIG. 3 is a plan view looking upwardly through a broken away portion of energy absorber 37 when installed in the position shown in FIG. 1. FIG. 4 is a cross-sectional view taken through FIG. 3, illustrating energy absorber 37 inverted from the position shown in FIG. I to facilitate illustration of the working parts. FIG. 4 therefore shows shaft 88 pointing downwardly instead of upwardly as it is actually installed in FIG. 1.

Energy absorber 37 in FIGS. 3 and 4 includes a pair of rotary pistons 42 and 42X to eliminate the need for a counter weight. Piston 42 is lighter than piston 42X by virtue of lightening holes 90 in piston 42 to provide dynamic balance with respect to shaft 88. Rotary cam means 49 is also made lighter than rotary cam 49X by holes 92 in rotary cam 49 for the same purpose. Bearing 125 of bronze material is disposed peripherally between cam 49, 49X and rotary piston 42 and 62X. Also the rotary pistons are laterally separated by a partition wall I27 thereby forming two separate chambers.

As shown in FIG. 3, output valves 46A and B are of the pressure relief type and more particularly of the compressible fluid-actuated type, operated for example by compressed air trapped in chambers 94 within cylinders 96A and B. Valving assemblies 98A and B include pistons 100A and B connected to valve discs 102A and B through stems 104A and B. Pistons 100A and B force valve discs 102A and B against 106A and B when the pressure in corresponding chambers is below a predetermined minimum pressure. The operating pressure may be varied by adjusting the pressure of compressed air in chambers 94A and B and this pressure may be programmed during portions of the cycle of operation if desired by a pressure varying arrangement not shown.

The following description directed to piston 42 applies also to piston 42X. Piston 42 is rotated in response to an input from shaft 88. Shaft 83 includes threads 108 for attachment to a linear storage and payout system. Enlarged portion H of shaft 88 is received within bearing H2, which is for example a journal bearing. Pressure for journal bearing H2 is obtained from pump chambers 68A and B through space 114 between rotary piston 42X and adjacent plate H6 of container or cylinder 40. Pressure from bearing 112 is discharged through small holes 118 extending into axial cavity 320 within shaft 88.

Inlet fluid 62 to pump 3% from container 40 is conducted through inlet passageway 48 and sector 50 within cam disc d9 whose sides 122 form an approximate l20 angle. The base of cutout sector 50 is a portion of a circle 122 as shown in FIG. 3 to provide adequate flow through to inner cam disc 49X. The cyclical phase of walls 122 of sector 50 relative to ports 52A, B and C through piston 42 directs inlet fluid during proper portions of the cycle into chambers 68A and B when they are not under compression. In FIG. 2 chamber 68A is under compression, which lifts valve disc 102A off its seat and discharges fluid through valve 46A. Valve fiB is closed because chamber 688 is not under compression and fluid is entering it through opened port 52A. Pressure is maintained by wiping seals 54, which are later described in detail in conjunction with FIGS. 6, 7A and 7B.

The phases of operation of rotary piston pump or energy absorber 37 are shown in FIGS. 5A through E, which illustrate the events occuring during one rotation of input shaft 83 During this single rotation of shaft 88, cam disc 49 engaged within piston 42 makes one revolution and piston 42 rotates in of a revolution. This rotation is effected by the described cam action of disc 49 rotating within circular hole 125 in piston 42. Immersion of the piston 42 and cam 49 within fluid 62 adequately lubricates relative rotation without undue wear and obviates the need for gearing between the cam and piston. Such gearing might, however, be utilized in the same manner as it is utilized in combustion engine versions of the Wankel engine.

In FIG. 5A the blank portion of 49 is opposite port 52C. Chamber 68A is therefore sealed, thus causing rotation of piston 42 to compress the fluid therein and creating a pressure which moves valve 46A off its seat to discharge into container 40. At the same time sector 50 is connected to port 52A which allows inlet fluid from container 40 to enter into chamber 683. Valve 46B is closed because there is not enough pressure to open it. Outer seal 54A wipes in contact with the pinch 69 between chamber 68A and 688 in FIG. 5A.

In FIG. 5B piston 42 has rotated slightly clockwise, but substantially the same flow conditions exist, with valve 46A being open and valve 468 being closed. There is one difference however, in that sector 50 is no longer connected with valve port 52A but with valve port 528 to allow fluid to enter the lower portion of chamber 68A.

In FIG. 5C fluid is still entering chamber 68A through aligned sector 50 and port 52B, but the pressure has as yet not been built up sufficiently in chamber 688 to open discharge valve 463.

In FIG. 5D the pressure in chamber 63A has been built up sufficiently to open discharge valve 468 and the arrows through it indicate the direction of flow. Sector 50 is no longer communicating with valve port 52B into chamber 68A, but with valve port 52C behind wiping seal 54A to allow fluid to flow into the portion of chamber 68B behind it.

In FIG. 5E valve 465 is still open between the seals effected by wipers 54A and 5413 plus discharging pressure through valve 468 while fluid is entering chamber 688 behind seal 54A through sector 50 and connecting port 52C. One revolution of shaft 88 has therefore rotated triangular piston 42 through via of a revolution. This provides a significant mechanical advantage and minimizes the mass of pump 38 to provide a given amount of energy absorption. The energy ab sorbed is given up in the form of heat into the body of fluid 62 within tub 40. Energy absorber 37 is particularly effective with the illustrated rotary piston-type of pump but an effective energy absorber may be provided by any rugged positive flow rotary pump such as a gear pump or a lobed pump.

FIG. 6 shows a form of wiping seal 54, including a spring urged wiping feeler 12 within a radial slot 126 in a vertex of piston 42. An end seal is provided by resilient strip 128 in peripheral end slot 139. These seals are, for example, of the type described in the aforementioned literature and patents relating to the Wankel type of internal combustion engine.

FIGS. 7A and 7B show a modified form of seal 131 having variable effectiveness in accordance with the internal pressure within housing 38. Seals 131 include a spring bow 132 of relatively large area having ends 134 received within longitudinal slots 13-5 adjacent the vertices of piston 42. FIG. 7A illustrates a low pressure condition in which bow seal 132 firmly contacts against the wall of housing 44. This is the condition that exists at relatively slow speeds of rotation and at no rotation.

FIG. 78 illustrates how spring bow sealing element 132 is deflected back against the vertices of piston 42 under relatively high speed and high pressure conditions of flow to bypass fluid between the vertices of piston 42 and the wall of housing 38. This minimizes the size of the inlet port. For example, onehalf of the available flow from the pump is dissipated between the rotor tips and the housing. This reduces rotor tip and housing wear and also reduces the stress level in the rotor. Spring bow wipers I32, for example, may be arranged to deflect and bypass at a pressure of 500 psi and over. Sealing to the housing is required to effect tensioning of the pendant 16 by means of a reverse pressure flow back to the rotor as discussed in conjunction with FIG. 2 and in the following detailed description of operation.

The power of an illustrative energy absorber of this type is, for example, 62,500 horse power, which would be capable of arresting a 125,000 airplane at 210 knots and 1,000 ft. ofline runout, within required operational capabilities. This would give such an aircrfit arresting device an energy capacity of 24l,000,000 foot pounds with a cable in a cable storage and payout system of the type described in the aforementioned copending application of 1% inches diameter. The cable weight, for instance, would be 3,600 pounds per engine making it 50 percent of the lightest airplane to be arrested. The dynamic loads used with a nylon tape cable storage and payout system would also be minimal. Assuming a pressure in the pump of 3,000 psi, the maximum flow would be 600 gallons per second or 26.5 gallons per shaft turn or 79.5 gallons per turn ofthe rotor. FOr a 16 inch deep rotor the diameter of the rotor would be 38 inches. With an allowable temperature rise of water at 40 F, the tub diameter would be approximately 8% feet storing 540 gallons. It is believed that outlet valves 46 need not be programmed, but if such becomes necessary, it can be accomplished to adjust to airplane weights ranging from 1 1,000-125,000 pounds.

Another important advantage of this invention is that it provides an energy absorber which is shallow enough to be mounted just under the deck of an aircraft carrier. This isalso extremely important in view of the minimal space available aboard vessels.

During the arrest, the orifices in lines 66A and 66B permit pressure to be accumulated in storage cylinder 58 for retrieval and pendant tensioning. Valves 46A and 46B are opened by pressure through lines 76, 77, 79, 87A and 878 when retrieve valve 73 is opened. This minimizes the pressure necessary to operate retrieve motor 74. As shown in FIG. 2, orifices valve 85 allows main outlet valves 46A and 468 to close after retrieve control valve 781s closed.

After retrieval, pendant i6 is tensioned by operating tensioning valve 82. This operates rotor 42 in a direction opposite to its rotation when absorbing energy and exerts a pull on the capstan side (not shown) of linear storage and payout system 34 when it is the type described in the aforementioned copending patent application and avoids the necessity of transmitting tensioning loads through motor 7d, sprocket assembly 80 and the connected portions of the linear storage and payout system 34. Only a small displacement is needed to tension deck pendant 16, but some fluid will leak through the bearing. A makeup pump for the accumulator 84 is therefore required to restore the necessary pressure and one-horse power pump 138 is sufficient. During arrest, it is necessary to close the tensioner valve 82 and this is accomplished from energy absorber pressure through lines 70 and 71 to tension valve 82. Tensioning may also be accomplished by a jacking motor (not shown) connected directly to shaft 38 which eliminates t e need for the illustrated reverse hydraulic and control cormections to pump 38.

FIGS. 8-11 show the pump control system 36A and details of rotary device 38A, which is useful as a pump or energy absorber. The system 36A consists primarily of a circular container or reservoir 40A vertically mounted between two bearing blocks 91A and 91B. The reservoir 40A contains hydraulic fluid 62A in which wall mounted rotary piston type pump 38A, is immersed. The rotary pump 38A includes a rotary cam or crankshaft 49A engaged with triangular piston or rotor 42A that rotates within a housing 44A having an epitrochoidal cutout 45A. The cut-out 45A forms two oval-shaped chambers 68A-68B. Connected to these chambers are diametrically opposing exhaust ports 47A and 478. From these opposing ports are connected two exhaust piping circuits 53A and 53B that will later be described in more detail. Crankshaft 49A has at its free end an axial suction inlet port 48A that provides the necessary communication between hydraulic fluid 62A via radial inlet ports 52A into chambers 68A-68B. Crankshaft 49A includes drive shaft portion 88A that axially extends through the flanged end wall of reservoir 40A, seal 79 and a sleeve bearing 81. Shaft 88A is connected to motor 89 through flexible coupling 93 to impart the necessary rotational power required by the pump.

For test purposes the reservoir 42A is rotatably mounted in bearings 91A and 918. A bracket 77 extends parallel and radially downward from the side wall of reservoir 42 to which load cell 75 is attached, thereby allowing for the various required torque test. Counterweights 87A and 87B are attached to crankshaft 49A to maintain the dynamic balance required, or unbalancing for test.

FIG. 12 illustrates the geometry details of the rotary pump 38A. A pinion gear 55 with center 57 is fixed to the stationary housing 44A. Rolling around this fixed pinion 55 is a ring gear 59 with center 61. This ring gear 61 is attached to the triangular piston or rotor 42A which has an outer point (R radially displaced from center 61. When center 61 is rotated once around center 57 at a constant angular velocity and with the gear teeth of pinion 55 and ring gear 59 in proper mesh, a line from R to center 61 will rotate at ls this constant angular velocity and point R will describe the element of the trochoid from R to R As center 61 is rotated two more times, point R will describe the trochoid from R to R and from R back to the starting position R on the last revolution of center 61. To accomplish this action with positively acting hardware, center 61 is driven by the crankpin (eccentric) of a crankshaft turning in the center 57 of the fixed pinion 55. Thus, the rotor 42A makes one complete revolution for every three revolutions of the crankshaft 49A; and three points on the rotor 43A-43C, equidistant from center 61 and spaced apart, each generate the trochoidal housing contour 45. The rotor 42A is machined to an appropriate arc between these points so that a minimum positive clearance (c) exists at the position shown in FIG. 13A.

The following schematic diagrams FIGS. TBA-13D illustrate various positions of piston 43A and crankshaft 49A, during operational cycle.

The rotary pump 30A is comprised of three pistons 43A-43C; that is each of the three faces of the rotor 42A. The pistons, by moving with the crankshaft 49A as we described previously, will suck fluid via axial inlet port 48A into the housing 44A and thence force it out of the housing; through valved exhaust port 47A or 47B dependant upon piston cycle position.

In FIG. 13A piston 43A is at top dead center. This means that the crankshaft 49A has pushed the rotor face to a point of minimum volume between this face 43A and the housing 44A; i.e., minimum cylinder volume for piston 43A. At this point it can be seen that the crankshaft inlet port 48A has just opened to the mating port 52A in the rotor 42A (it has in fact opened at 24.9 before T.D.C., measured in crankshaft rotation). The volume which will be swept by piston MA will fill from the crankshaft l9A as shown in FIG. 13B, while fluid is being forced out of the machine by piston 413B, through the exhaust port 47B on the periphery of the pump housing 44A.

Following the rotation of the crankpin center 61 about fixed center 57, as shovm in FIG. 13C that when the crankshaft 49A has turned 270piston 43A has rotated 90 and is at bottom dead center (B.D.C.); i.e., maximum cylinder volume for the piston 43A. At this point the crankshaft inlet port 48A just overlaps and closes the inlet port 52A for piston 43A, and the discharge stroke commences.

Referring to FIG. 13B, piston 43C is at bottom dead center and FIG. 13C shows piston 43C in its discharge stroke position.

In retracing the motion of the rotor as shown in FIGS. 13A and 13B, it will be seen that piston 43A returns to top dead center in the next 270 of crankshaft rotation. This condition is shown in FIG. 13D with piston 43A facing the opposite exhaust port 47B from the condition shown in FIG. 13A, 540 earlier in the cycle.

Clearance between rotor tips R R and R and chamber wall 45A ranges from 0.030 to 0.043 inches (average 0.037 inch) yet allows adequate operating pressure to be maintained, such as maintaining 1,600 psi at 700 foot pounds of shaft torque.

OPERATION F I68. 8 and 9 illustrate rotary piston type pump 38A, which is a scale working model of a full size machine.

As shown in the drawings, hydraulic fluid 62A passes through axial inlet chamber 33A into cut-out section 50A of rotor 42A, whereby it is directed radially through ports 52A into chamber 68A. The slug of fluid directed into chamber 68A is trapped by piston face 43A as rotor 42A rotates, whereby it is discharged into exhaust piping system 533 via exhaust port 47B. Exhaust piping system 5313 is a pressure controlling system that conveys the fluid 62A from the exhaust port 478 to reservoir inlet 73B.

Fluid 62A leaves exhaust port 473, flows through tee 63B, having connected a pressure gauge 658, then through adjustable orifice 673 or fixed orifice plate 698. The fluid continues through shut-off valve 713, from which it reenters reservoir 40A at inlet 73B. Exhaust piping system 53A connected between exhaust port 47A and 73A serves the identical function. The adjustable and fixed orifices control the exhaust pressure and resultant torque in conjunction with the area of the clearance between the rotor tips and easing.

Iclaim:

1. A rotary piston pump comprising a housing having an epitrochoidal cross section with a pair of chambers, a triangular piston means with convex sides and a centered circular aperture, rotary cam means having cam disc means rotatably inserted within said circular aperture in said piston means for rotating it in said housing, said cam disc means being secured to a rotatable cam shaft means, outlet valve means in each of said chambers, inlet conduit means extending radially through said piston means and through said rotary cam means whereby fluid is conducted into said chambers of said pump from which rotation of said piston means discharges it through said outlet valve means, inlet valve means disposed in said inlet conduit means, said inlet valve means comprising inlet valve port means extending radially through said piston means, inlet channel means extending axially through said camshaft means and radial cutout means through said cam disc means.

2. A rotary piston pump as set forth in claim 1 wherein said outlet valve means are of the pressure relief type.

3. A rotary piston pump as set forth in claim 1 wherein said housing includes a dividing pinch between said chambers, and said outlet valve means comprise a pair of outlet valves each disposed adjacent diametrically opposite sides of said pinch for prolonging the compression portion of the pumping cycle.

4. A rotary piston pump as set forth in claim 1 wherein said radial cutout means in said cam disc means approximately comprises a sector in said cam disc means.

5. A rotary piston pump as set forth in claim 5, wherein said sector covers arpproximatelv and the corresponding portrons of said in e valve port means through said piston means cover substantially less are than the contacting portions of said sectors.

Claims (5)

1. A rotary piston pump comprising a housing having an epitrochoidal cross section with a pair of chambers, a triangular piston means with convex sides and a centered circular aperture, rotary cam means having cam disc means rotatably inserted within said circular aperture in said piston means for rotating it in said housing, said cam disc means being secured to a rotatable cam shaft means, outlet valve means in each of said chambers, inlet conduit means extending radially through said piston means and through said rotary cam means whereby fluid is conducted into said chambers of said pump from which rotation of said piston means discharges it through said outlet valve means, inlet valve means disposed in said inlet conduit means, said inlet valve means comprising inlet valve port means extending radially through said piston means, inlet channel means extending axially through said camshaft means and radial cutout means through said cam disc means.

2. A rotary piston pump as set forth in claim 1 wherein said outlet valve means are of the pressure relief type.

3. A rotary piston pump as set forth in claim 1 wherein said housing includes a dividing pinch between said chambers, and said outlet valve means comprise a pair of outlet valves each disposed adjacent diametrically opposite sides of said pinch for prolonging the compression portion of the pumping cycle.

4. A rotary piston pump as set forth in claim 1 wherein said radial cutout means in said cam disc means approximately comprises a sector in said cam disc means.

5. A rotary piston pump as set forth in claim 5, wherein said sector covers approximately 120* and the corresponding portions of said inlet valve port means through said piston means cover substantially less arc than the contacting portions of said sectors.

Images