US 2632398 A
Description (OCR text may contain errors)
March 24, 1953 w. FERRIS 2,632,398
SPRING FOR [meme ouTw THE VANES 0F VANE TYPE HYDRODYNA c MACHINES 2 SHEETS-SHEET 1 Filed Dec. 5, 1946 I INVENTOR. WALTER FERRIS WW ATTORNEY March 24, 1953 w. FERRIS 2,632,398 SPRING FOR URGING OUTWARD THE VANES OF VANE TYPE HYDRODYNAMIC MACHINES 2 SHEETS-SHEET 2 Filed Dec. 5, 1946 IN VEN TOR.
WALTER FERRIS ATTORNEY Patented Mar. 24, 1953 SPRING FOR URGING OUTWARD THE VANES OF VANE CHINES TYPE HYDRODYNAMIC MA- Walter Ferris, Milwaukee, Wis., assignor to The Oilgear Company, Milwaukee, Wis., a corporation of Wisconsin Application December 5, 1946, Serial No. 714,248
This invention relates to hydrodynamic machines of the sliding vane type. Such a machine includes a rotor which is enclosed in a chamber having inlet and outlet ports for the flow of liquid to and from the rotor, a plurality of vanes which are slidable in slots extending inward from the periphery of the rotor, and an endless vane track which extends around the rotor to engage the outer ends of the vanes.
The vane track may be stationary, in which case the displacement of the machine is constant, or it may be adjustable to vary the displacement of the machine. If the vane track is stationary or if it is adjustable and the machine is adjusted to perform useful work, a portion of the vane track adjacent one end of each port is arranged close to the periphery of the rotor and a portion of the vane track adjacent the other end of each port is spaced farther from the periphery of the rotor so that the vanes are caused to move inward and outward of the rotor as the outer ends thereof ride upon the vane track during rotation of the rotor.
Sliding vane type hydrodynamic machines are in extensive use as pumps but such a machine may be employed as a motor if it is properly designed. In either case, the outer ends of the vanes must remain firmly in contact with the vane track as they pass from each port area to the adjacent port area, as otherwise the machine would fail to function, and it is practically essential that the outer ends of the vane continuously engage and follow the vane track in order to obtain quiet and satisfactory operation of the machine.
A pump is ordinarily operated at such high speed that it is only necessary to hydrostatically balance the vanes as the centrifugal force will hold the vanes in contact with the vane track but a motor is often started under load and is often operated at such low speed that the centrifugal force is insufiicient to hold the vanes in contact with the vane track. Therefore, if the machine is to function as a motor or is to function as a pump and be driven at low speeds, means must be provided for holding the vanes in contact with the vane track and in a motor the vanes must be in contact with the track before the motor is started.
The vanes of a machine have heretofore been held in contact with the vane track by supplying to the inner ends thereof liquid at a pressure higher than the pressure of the motive liquid as shown, for example, in Patent No. 2,335,567. A machine provided with such a system is entirely satisfactory from an operating standpoint but the mechanism for supplying high pressure liquid to the inner ends of the vanes adds considerably to the cost and to the overall dimensions of the machine.
It has also been proposed to provide vane type machines having springs for urging the vanes into engagement with the vane track but as far as is known no such proposed machine was capable of meeting commercial requirements, particularly as to machines for use with liquid and for operating at high pressures such as at or above 1000 p. s. i.
The present invention has as an object to provide a vane type hydrodynamic machine having novel spring means for urging the vanes into engagement with the vane track.
Another object is to provide a vane type hydrodynamic machine which will operate successfully at low speeds as well as at high speeds and under high or low pressure and which has overall. dimensions substantially no greater than those of similar vane type machines which are capable of operating only at high speed.
Another object is to provide a vane type hydrodynamic machine which has springs for urging its vanes against its vane track and which is capable of operating successfully in commercial use for a very long period of time.
Other objects and advantages of the invention will appear from the following description of the hydrodynamic machine illustrated in the accompanying drawings in which the views are as follows:
Fig. 1 is in part an elevation of and in part a transverse section through a machine in which the invention is embodied, the section being taken on the irregular line l| of Fig. 2.
Fig. 2 is a longitudinal section taken along one face of the rotor as indicated by the line 22 of Fig. 1.
Fig. 3 is an enlarged view of the vane and the vane spring shown in the upper part of Fig. 1.
Fig. 4 is a section taken on the line 44 of Fig. 3.
Fig. 5 is a face view of one of the cheek plates, the View being taken on the line 5-5 of Fig. 1.
Fig. 6 is a diagram of the circuit for supplying liquid to the inner ends of the vane.
Fig. 7 is a view somewhat similar to Fig. 3 but showing the spring reversed.
Fig. 8 is a, view taken at right angles to Fig. 7.
The machine chosen for illustration is of the general type shown in Patent No. 2,335,567 to stood that the invention is equally applicable to I both pumps and motors and to both constant and variable displacement machines.
As shown, the motor has its mechanism arranged within a casing I having two connections 2 and 3 by means of which the motor may be connected into a hydraulic circuit and Which may function interchangeably as the inlet (and outlet of the motor.
Casing I has a circular chamber 4 formed :therein and closedbya removable end head 5;
Ghamber hasa spacefring 6 fitted therein between two cheelrjplates T-and 8 which engagethe inner wall of chaniberfli' and the inner face of head 5 respectively; Spacer ring 6 and cheek plate I and enclose a circular rotor 9 which is fixed for rotation with a shaft Hand is just enough thinner than spacer ringt to permitit to rotate freely between cheek pl tes I and 8 and at the's ame time maintain substantially liquid tight seals bctw'e en'its opposite faces and the cheek plates. Shaft It extends outward through casing I for connection to 'adeviceto bedriven and it is rotatably supported by, suitable bearings, one bearing being shown at I I;
o or 9 has a ur i y oir ne's I5 extending inward from its peripheryand avane I6 slid- ,ably fitted in each slot. The outer ends" of vanes I6 engage anendlessvane track iTwhich in the presentinstance has been shown as being formed l b'oflihe' inner periphery of acer r n ,6 but which may beatseparate structure and be adjustable in any suitable manner to vary motor displacement such, for example, as shown in Patent e-2 3069,-
In the embodiment shown, vane track I! is ap proxima ly i t c and' ametrica QPPbS a '3 n the $51 115 Q t lea d mc and two diametrically opposed arcs I9 in the reeiqns Q t ate t d eme A s 8 e preferably but not necessarily concentric with rotor 9 andere de i a e erein a se l n r s A 1% e d s ated he ein as Wo a c an p ifif i r bl a n y y? not ui e c n tri w th r torv 9 o th t the rt ons of v e ack ll intermediate arcs I 8 and I9 may be given a curvature which will produce, satisfactory rates of inward and outward movements of vane I6 as rotor 9 rotates. Thelength of each arc l and I9, is at least as great as the angular distance between the outer ends of two adjacent'vanes I6.
In order that the hydraulic forces actin upon rotor 9 in radial directions may be balanced, the space between'vane track I! and the periphery or rotor Sis divided intdt'wo equal and diametrically opposed fluid sections by the vanes I 6 in contact withsealing' arcs I3, and each fluid section isdivided into an inlet area and an outlet area by the vane 'or vanes in contact with working arc I9.
'Motive liquid is admitted between the outer ends of the van'es as they pass through the inlet areas, and this motiteliquid acts upon the vanes in contact with the workingarcs I9 and effects rotation of rotor 9. If the machine were to operate as apump, rotorj 9 would be rotated mechanically andthetvanes would transfer liquid from the inlet 4 areas to the outlet areas as they passed across working arc I9.
Cheek plate 1 has two diametrically opposed ports 29 and two diametrically opposed ports 2| formed therein adjacent the periphery of rotor 9. Each port 29 extends from a point near one end of an arc I9 to "a pointnear the adjacent end of an arc I8 and each port 2i extends from a point near the other end of arc I9 to a point near the adjacent end of the other are I8. Both ports 2i) communicate with an arcuate passage 22 which is formed in casing I and communicates with connection 2 through a passage not shown. Both ports 2| communicate with an arcuate passage 23 which is formed in casing I and communicates with connection 3 through a passage not shown.
Ports 29 and 2 I may function interchangeably asinlet and outlet ports and the space between vane track I? and rotor 9 adjacent each port may be designated an inlet area if that port is functioning as an inlet port or designated an foutlet area if th'at'portis functioning a an outlet'port.
vCheek plate 3 is also plbvid d with ports 20 and 2t each or which is in axial alinernent with the corresponding port incheek'plate'l so that all hydraulic forces acting assurance 9 in an axial direction'are balanced." n
As vanes 'I'o move inward and outward in slots 15 during rotation Of rotor 9,lid1 i'd 'willifiow into each van-e slot as the vanetherein' moves outward and liquid will be expelled from each'vane'slot as the vane therein moves inward. In brd'eiito provide for'this' flow of liquid to and from the vane slots and" also to hydrostatically balance the vanes as the outer ends thereof pass through the inlet and outletare'as; eacliof cheek plates I and8"'has"twoarcuate groovesor viane slot ports 24 and two arcuatgrooves or'van-e'slot ports 25 formed in its'inne'r was upon a radius equal to the radius of the inner "ends ofvane slots I 5 so that vane slots I5 'will'reg'ister successively with'the vane slot ports as rotor 9 rotates; "Each vane slot port 24 is radially inwardffro'm a port 20 and is connected thereto by a'gmove 26 formed in the outer face of the cheek plate. Each vane slot'port 25 is radially inward "from a port'2l and is connected thereto by a groove 27 formed in the outer face of the'cheek plate." The arrangement is such that both the inner and outer ends of the'vanes are subjected tothe same pressure when the outer ends of the vanes aremovmg through'tl'ie inlet areasand whenthe outerends" of the vanes arernoving through the outlet areas'so' that the "vanes "may be kept in contact'with "the 'vanetrack' by application of a relatively small radial force.
"I dc ha he Whose ou en s are in contact with the arcs I8 and I9 may have their inner ends subjected to pressure, each of cheek plates 7 and 8 has formed in the inner face thereof two vane slot orts 28, each of which is radially inward from a sealing arc I8 and is mid-way between the adjacent ports Hand 25, and two vane slot ports 29 each of which is radially inward from a Working arms and is midway between the adjacent ports' 26 and 25. Ports 28 and 29 are supplied with liquid from a port 2ll'or a port 2 'I whichever is ahig hpressure port. As shown, all four of the portsf' 25 and 29 in cheek late 8 communicate with a groove 30 which'is formed in the outer face of cheek'plate s and communicates with a channel 3I having two branches 32 and 33 which are connected, respectively, through, a valve 34, and Ya channel '35 we port and through a valve 36 and a channel 37 to a port 2|.
Valves 34 and 36 may be ordinary check valves, in which case the pressure in ports 28 and 29 is the same as in high pressure port 20 or 2|, but valves 34 and 33 preferably are pressure reducing valves as will presently be explained.
A vane in contact with a sealing arc I8 or a working arc l9 has one side thereof subjected to the workin pressure and the other side thereof subjected to the exhaust pressure which ordinarily is zero or so low as to be negligible. If a vane in contact with a sealing or working arc were stationary and the exhaust pressure were zero, the film of liquid under the vane would have a pressure which would be equal to the working pressure at one side of the vane and would decrease to zero at the other side of the vane so that the force tending to move the vane inward would be equal to the cross-sectional area of the vane multiplied by one-half of the working pressure and the vane could be hydrostatically balanced by subjecting its inner end to a pressure equal to one-half of the working pressure.
However, it has been found in practice that the forces required to hold the vanes in contact with the sealing arcs and the working arcs are greater when the machine is operating than when the machine is idle. For example, when a machine is operating under certain conditions, the force tending to lift a vane off from a sealing are or a workin arc is equal to the cross-sectional area of the vane multiplied by approximately 70% to 80% of the working pressure.
The force for holding the vanes against the vane track should exceed the lift-off force but, if a vane in contact with a sealing are or a working arc had its inner end subjected to full working pressure which would be the case if channel- 3| were connected to ports 20 and 2| through check valves, that vane would be urged against the working or sealing are by a force equal to the difference between the hold-on and the lift off forces.
In the above example, if the pressure of the motive liquid were 1000 p. s. i. and each vane were .13" thick and 1" wide which is a common size vane, the hold-on force would be 130 pounds and the lift ofi force would be 91 pounds. Therefore the vane would bear upon the sealing or working arc with a force of 39 pounds which would be a greater force than could be safely supported by the small area of film under the end of the vane and might cause excessive wear or gallin of the vane and/or the vane track.
It is therefore desirable to reduce this bearing force and this may readily be accomplished by providing valves 34 and which will reduce the pressure in vane slot ports 28 and 29 a predetermined amount such as 20% which under the conditions outlined above would reduce the bearing force by two-thirds.
As shown, valve 34 includes a casing having a bore 4| and a counterbore 42 formed therein, a valve 43 fitted in bore 4|, piston 44 fitted in counterbore 42 and ordinarily formed integral with valve 43, and a light spring 45 arranged between piston 44 and the end wall of counterbore 42 to normally hold Valve 43 in its closed position and having only a little more strength than is necessary to overcome the friction and inertia of valve 43 and piston 44. Bore 4| has channel 35 connected thereto adjacent the end thereof. It has branch 32 of channel 3| connected thereto at such a distance from its end 6 that valve 43 blocks the end of branch 32 when valve 43 is in its closed position, and counterbore 42 has channel 3| connected thereto adjacent the end thereof.
Since valve 36 is exactly the same as valve 34 except that it has channel 31 and branch 33 connected thereto instead of channel 35 and branch 32, a description of one will suifice for both as corresponding parts have been designated by corresponding reference numerals with the exponent a added to the reference numerals applied to valve 36.
The arrangement is such that, when pressure increases in port 20, pressure will extend therefrom through channel 35 to bore 4| and shift valve 43 against the resistance of spring 45. As soon as valve 43 starts to uncover the end of branch 32 of channel 3|, pressure willextend through channel 3| to ports 28 and 29 and also to the counterbores 42 and 42 The pressure in counterbore 42 will act upon piston 44 and tend to close valve 43 and the pressure in counterbore42 will act upon piston 44 and cause it to assist spring 45 in holding valve 43 closed.
Valve 43 and piston 44 are so proportioned that,
when port 20 is a high pressure port, valve 34 maintains in ports 28 and 29 a pressure equal to a given percentage of the pressure in port 20. For example, if it is desired that the pressure in ports 28 and 29 be 20% less than the working pressure, valve 43 and piston 44 are so proportioned that the force exerted upon valve 43 by the working liquid will be balanced by the forces exerted on piston 44 when the pressure in counterbore 42- is of the working pressure. Therefore, an increase in the working pressure or a decrease in the pressure in counterbore 42 will cause the valve 43 to open and a decrease in working pressure or an increase in the pressure in counterbore 42 will cause the valve 43 to close so that the pressure in counterbore 42 and also in ports 28 and 29 is maintained at substantially 80% of the working pressure.
When port 2| becomes the high pressure port, valve 33 opens to admit pressure to ports 28 and 29 and to counterbores 42 and 42, the pressure in counterbore 42 assisting spring 45 in holding valve 43 closed. Thereafter, the pressure in ports 28 and 29 is maintained at a given percentage, such as 80%, of the working pressure by valve 36 which operates in the same manner that valve 34 operates when port 20 is the high pressure port.
It has been previously explained that the outer ends of the vanes must remain continuously in contact with the vane track in order to obtain quiet and satisfactory operation of the machine, that the vanes are hydrostatically balanced as the outer ends thereof pass through the outlet and inlet areas, and that the present invention provides springs for maintaining the outer ends of the vanes in contact with the vane track.
The greatest difficulty encountered in providing springs for holding the vanes against the vane track is due to the necessity of arranging both a vane and a vane spring in a vane slot which is very small. A common size rotor is a little less than 1" thick and has vane slots which are about 9 64" wide and extend radially inward about A". Each vane slot is thus only about 1" by A by 934"- If the vane slots were extended farther inward from the periphery of the rotor, the metal between the inner ends of the adjacent slots would be reduced which would weaken the rotor at the subjected to high pressure liquid on one side thereof and to low pressure liquid on the other side thereof. -If the size of the vane slot were increased by increasing the diameter of the rotor,
the size, weight and cost of the machine would be increased without a corresponding increase in volumetric capacity.
It is thus desirable that the springs be added without altering the size of the vane slots but the space available for each spring is very small p r c la w n he e is n it e rem i war p it n- Th e e e ch s r ng m s be verysmall and it must have a great deflection relative to its size due to the distance through which the vane moves radially. Also, the spring must be capable of moving a vane outward and holding it against the vane track when the compression of the spring is the least.
The vane springs must therefore be very small but, by hydrostatically balancing the vanes as the outer ends thereof pass through the inlet and outlet areas so that the force required to move a vane radially is very small, a spring having sufficient strength to move a vane outward and hold it against the vane track may be inserted in each vane slot by forming a notch in the inner end of each vane to provide a space for the spring.
As best shown in Fig. 3, each vane !B has a notch 50 formed in the inner end thereof to provide a space for a spring and to retain spring 5! in position in vane slot !5. Spring 5! includes two spaced apart torsion coils 52 and 53 which are relatively large in diameter and have the axes thereof normal to the radial path of vane l6, an intermediate section 55 connecting coils 52 and 53 to each other and holding them in spaced relation, and two spring arms 55 and 55 extending from coils 52 and 53 respectively. The free ends of arms 55 and 56 are curved and flattened and are adapted to slide upon the inner end of vane slot !5 as spring 5! is compressed and expanded by radial movements of vane 5.
Spring 5! may be formed by arranging two mandrels of the proper diameter in fixed positions the proper distance apart and winding a length of small diameter spring wire around one mandrel to form a tight coil 52 and then winding the wire around the other mandrel to form a ti ht coi 53- 'Ihe e' Wound n, t s e rec e ermine b. end s hat a 55 extends from one end of coil 52 and arm 55 extends irom he o posi n o coil e mediate section 54 is bent adjacent each coil an amount sufiicient to bring the two coils into the same plane and each of arms 55 and 5B is bent at or nearits junction with a coil to cause the arm to slope toward the other arm.
The length of each of coils 52 and 53 is less than the width of a vane slot. For example, if the vane slot is wide, spring 5! may be formed from .023 diameter spring wire and each coil may consist of four turns so that each coil is long which allows clearance between the ends of the coils and the walls of the vane slot.
In a machine having two fluid sections as shown in Figs. 1 and 2, each vane spring is compressed and expanded twice durin each revolution of the rotor. Hydraulic motors are often operated for long periods of time at 1000 iii R. P. M. or more. At 1000 R. P. M., each vane spring will be flexed 2000 times per minute which amounts to nearly one, million flexings in one work day of eight hours. A vane spring to be successful must, therefore "be capable of being flexed through a wide range with great rapidity and of withstanding many millions of flexings.
If a vane spring were constructed without torsion coils or with torsion coils of relatively small diameter, the greater part of the flexing of the spring would occur in very limited sections of the wire and the metal in those sections would become fatigued and cause the spring to fail after the machine had been in use only a short time.
However, in a spring having torsion coils of relatively large diameter as shown, the greater part of the flexing is distributed throughout much greater sections of the wire which enables the spring to be flexed with great rapidity and to have a long life. In fact, springs constructed as shown appear to be in perfect condition after being taken from a motor which had been run for long periods of time during which each spring was flexed several million times.
As spring 5! is compressed and expanded in response to inward and outward movements of vane !5, the ends of arms 55 and 55 slide back and forth upon the bottom of vane slot !5. In order to avoid undue wear of arms 55 and 55 due to these sliding movements, the bottom of slot I5 and the curved and flattened ends of arms 55 and 55 are polished to reduce the friction therebetween. Since the inner end of each vane slot always contains some of the working liquid which almost invariably is a good grade of oil, the friction between the bottom of vane slot i5 and the ends of arms 55 and 55 is negligible.
Inward and outward movements of vane !5 also causes coils 52 and 53 to move radially in slot :5 but the length of each coil is less than the width of slot !5 as previously explained, there is no force urging coils 52 and 53 against either wall of slot !5, the walls of slot I5 are made fiat and smooth to reduce the friction between them and vane E5, and the walls of slot !5 are well lubricated by the working liquid. Therefore, there is substantially no abrasion of the ends of coil 52 and 53.
However, all danger of abrading the ends of coils 52 and 53 may be avoided by reversing spring 5! as shown in Figs. '7 and 8. That is, coils 52 and 53 may be supported upon the bottom of vane slot !5 and the ends of arms 55 and 56 caused to slide upon the end wall of notch 55.
Spring 5! is normally centered between the two sides of rotor 9 and, if it should move axially of rotor 9, the ends of one of arms 55 and 56 would engage a side wall of notch 50 and shift spring 5! back toward center. However, it is desirable to keep spring 5! centered and this may be accomplished in various ways such as by forming in the bottom of vane slot 15 a, recess 5'! to receive spring 5i and to restrain it from any substantial movement axially of rotor 9.
Recess 5'! may be formed in any suitable manner but, since it is common practice to form a small round hole at the inner end of each vane slot as shown in Fig. 2, recess 5'! may be provided by a counterbore 58, as indicated by the dotted circle in Fig. 8. The depth of recess .5! has been exaggerated in the drawings for the purpose of illustration but only a very shallow recess is required to restrain spring from moving axially of rotor 9.
With the vane spring reversed as shown in Figs. 7 and 8, the torsion coils do not move radially in response to radial movements of the vanes. Therefore, no abrasion of the coils can occur.
The invention herein set forth is susceptible of various modifications without departing from the scope of the invention which is hereby claimed as follows:
1. A spring for urging radially outward a thin vane which has a bearing surface on its radially inward edge and is fitted in a narrow slot which is formed in the rotor of a hydrodynamic machine and has a bearing surface at its radially inward end, said spring being formed from a single strand of small diameter spring wire and comprising two torsion coils of such lengths that said spring can flex freely when arranged Within said slot, an intermediate section connecting one end of one of said coils to the opposite end of the other coil to hold said coils in spaced relation and in position to bear upon one of said surfaces, and an arm extending from the other end of each of said coils outward and toward the other coil to engage and slide upon the other of said surfaces as said vane moves radially in said slot.
2. A spring for urging radially outward a thin vane which has a bearing surface on its radially inward edge and is fitted in a narrow slot which is formed in the rotor of a hydrodynamic machine and has a bearing surface at its radially inward end, said spring being formed from a single strand of small diameter spring wire and comprising two torsion coils arranged in the same plane and each formed by at least three turns of said strand and having a length less than the width of said slot, an intermediate section connecting one end of one of said coils to the opposite end of the other coil to hold said coils in spaced relation and in position to bear upon one of said surfaces, and an arm extending from the other end of each of said coils outward and toward the other coil to engage and slide upon the other of said surfaces as said vane moves radially in said slot.
3. A spring for urging radially outward a, thin vane which has a bearing surface on its radially inward edge and is fitted in a narrow slot which is formed in the rotor of a hydrodynamic machine and has a bearing surface at its radially inward end, said spring being formed from a single strand of small diameter spring wire and comprising two torsion coils adapted to engage one of said surfaces and of such lengths that said spring can flex freely when arranged within said slot, an intermediate section connecting one end of one of said coils to the opposite end of the other coil to hold said coils in spaced relation and so shaped that it holds the corresponding ends of said coils in the same plane, and an arm extending from the other end of each of said coils outward and toward the other coil to engage and slide upon the other of said surfaces as said vane moves radially in said slot.
REFERENCES CITED The following references are of record in the file of this patent:
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