US2846984A

US2846984A - Motor construction

Info

Publication number: US2846984A
Application number: US467717A
Authority: US
Inventors: Robert E Zwayer
Original assignee: Aro Equipment Corp
Current assignee: Aro Equipment Corp
Priority date: 1954-11-09
Filing date: 1954-11-09
Publication date: 1958-08-12
Anticipated expiration: 1975-08-12

Description

I12, 1958 R. EV. ZWAYER 2,846,984

MOTOR CONSTRUCTION Filed Nov. 9, 1954 2 Sheets-Sheet l INVENTOR. ROBERT E.ZWAYER ATTORNEYS Aug. 12,

Filed Nov.

R. E. ZWAYER 2,846,984

MOTOR CONSTRUCTION 9, 1954 '2 She'ets-Sheet 2 my air}; 55 g; $z 4000 7 TORQUE- lb. ft.

55 CUBIC FT 45 35 PER MIN.

7 TORQUE- lb. f1.

JNVENTOR.

ROBERT E. ZWAYER JM W ATTORNEYS United States Patent y 2,846,984} Mor nicmssrnu rlom Ro w y nBr qi 1 .1 a si n n A quipment Corporation,- Bryan, Ohio, a corporation ofyOhi'o pp ic t o N v mb r g l54, SeriaLNo. 467, 17

s claiip cl' 1 2 1--;--s4 I This invention relates generally to a motor construcmm, and 'morepar'ticularly:to a reyersible pneumatic.

motor of, the rotary -,va'ne type.

The motor construction of the ,present invention may be p'l is hea i WiFE$ f. he. paema si for moyingload's fromone height; level to another., Such,

hoisting devices generally utilize a'reyersible type motor having suitable controls for changing both the speed and the direction of dr iving rotatipn. v During the practical operation of such hoists, the motor is. not needed to effect lowering of the load, and ;lowering. may beeffectedby.

gravity force,alone,-lregulated. by brake means. It will be apparent frpm tl e pres'ent inyention that if some of the potential on the -reverse side oi the motor can be, transferred to th e forwardside, while retaining sufiicient motor power 'in reverse operation to drive an, empty Q 't chain d w wardlyat ar asanab spee t em can serve the hoist with substantially greater cfficiency,

er y, abl nslt fl h st o; and e: eav qa at sh flspee sl,

, It s P imaIY biQ L QI iQ sqntg ye ion h fore, ,tqr e numa 9 q q t tion, f e. ry, v n pe hav bs nt a gr aaedrow in the forward or lifting direction of driving operation as compared to the performance of prior art constructions, wherein the gain in; power ;in the forward or lifting direction isfigreater than tbe loss in power in the reverse or lowering} direction,;

It is another object to proyide a reversible pneumatic motor of tha -rotary ivane type havinga compressed air inlet and a;pair ;of ports comprising-primary- -and secondary exhausts, wherein the primary exhaust; isparticularly positioned in unbalanced relationbetween;the inlet and the secondary exhaust,

It is a further. object to, provide, a motor, construction. 2 he. yp fis t d, ,whsx iaa ha ma hau is unba nwdataaan l o iupt about Off, n e

he ndfl 'ther, i qta ny ew my nv nt on consists in the construction, arrangement and c'ornbinaus parts of my motor. construction whereby the objects contemplated are obtained as herea e marefu y et o th; po n out in m m tion of}, the va and illustrated in Ithe accompanying drawing, wherein; Figure l is a side eleyational view, partly inper- Pt eL 9winsap eumati; 9$? e e j c type nfw ish t heuma c; moto i on t t q b the p s inv nt on e .ze L

Figure 2 is a fragmentary vertical sectional view, of:

hw nst ust qn; tE s r i na enla ed a a h ng e li bi. on ngdf. h uanei m ic moto Figure 3 is 'ano e e'tional view, on a further ena ed scale, tak n tantia y. nd a 1;. the l ne 3, qaF 't te 22, 1 in t e Pa lar location Q -Ih eria l r sum t qe P tted a a t mane. a h forward and reverse rotation of a pneumatic m otor conru iqn orr n n IQ i u e 3 whe e n Pr y exhaust isparticularly located in oiIset relation at, an

angle of about 28 frornxcnter;

Figure] is another plgt sirhilar to,' Figure 6,; for a Qw wQn rw -Q sqae I12aa i Jq=E g w er in-v the primary exhaust, is particularly' locatedtin ofiset relaw tion at an angle of about .13? from eenterttand,

Figure: 8 is another plot similar; to, Figures 6 and. 7, for a motor, construction correspondingto Figure 5, ,wh erein the primaryexhaust is in balanced,arrangement in the.

manner of the prior art Referring nowmoreparticularly ,to Figures l to 3 of the drawing, I have used the I reference. numeral 10 to indicate the .housing ofia typical hoisting device in which the motor,construction, of. the present inventi0n..may be employed Theihousing fl tl lis of, ..holl ow formv andlen closes a stator 12 havinglalcyl indrical jbore.fthereindef fining a cylindrical internal surface surroundingta rotor 14 ,rotatably mounted, on al motorlshaftelbg The rotor: 14,,isformed1with a plurality pf. rad-iallyaextending vane slots 18; ,which serve, t-oreceiv'ei a corresponding plurality of radially; outwardly wslidable vanes :20} The yanes moveioutwardlyin theslots ls rin response to centrifugal forces when the' rotor. 14 ;is .driven,\ and serve to effect continuousgcontacting.engagerne ntwith the internal surface formed by the stator 12.

As .be s t.,seen in Figure 3 .otthe drawingtthe longitudinal axis of the bore of, the stator. 12; is eccentrically disposedjrelative to ,ther coincident axes of the housing ltl and the rotor, l l inr the conventional manner .of pneumatic:motor constructions A -lower portion of the outer cylindrical surface thelrotor ld contactingly en- Flexibl e elements- 36 and-3 8;are suspendedsfrom the,

ends Qot a control lever v40-, andiserve to permit manual rotation ofi a.,rock;shaft- 42 for. motor-forward or load.

up operation and motor-reverse or load down opera tion, respectively. The rock shaft 42' effects control actuation-of a suitable airiregulating .valve and brake, not

illustrated :in detail hereinbut of the general type shown and described in co-pending Zwayer application Serial No. 490,968,'filed February 28, 1955,'having a common assignee withthe present invention.

As best seen in'Figure, 2 of the drawing the motor shaft 16 is rotatably mounted in

suitable bearings

44 and 46. a vei' tegs is provided overthe righthand end ot ,the' housing" 10, as vi ewed;in Figured, andserves to; enclose the rotor 14 within the hoist housingfl The platel 8v s Pr-Q i' with pi ti s d: r al -fit i h h isnadapted to be connected to a suitable source of air under press ure, The airv supplyi delivered by the fitting 50 om uni t s! ht v h itf tz a ir; t passageways (not shown) with. a first air inletvport -52 and :asecond r kaPs t low hwu hthe iri ak passage-j Wars fiebl v s slatais at or aid i l n altat p pitl. le tiya PPPlx- L nw ither on the Patented Aug. 12, 1958 3

l ports

52 and 54 in response to manual rotation of the rock shaft 42.

The

ports

52 and 54 are positioned at opposite sides of and closely adjacent the rotor-stator seat 22. When an incoming supply of air is admitted at the inlet port 52, it will be apparent that expansion of the compressed fluid will perform work against the operating surfaces of the vanes 20, and thereby effect a forward or clockwise rotation of the rotor 14, as indicated by the direction arrow 56 in Figure 3. Such clockwise rotation corresponds to the load up direction of movement of the chain 30. When air is alternatively admitted at the inlet port 54, it will be apparent that reverse or counterclockwise rotation of the rotor 14 will be effected, as indicated by the direction arrow 58, and such rotation corresponds to the load down direction of movement of the chain 30. For purposes of reference, I have designated the longi tudinal axial center line through the motor shaft 16 by the letter 0. The radial line from the center through the center of the port 52 has been designated as station A, and the similar line through the port 54 as station B. The vertical center line through the top of the motor construction has been designated as station C.

It is the particular location of a plurality of primary exhaust ports 60 which constitutes the essence of the primary invention. The radial line through the center of the primary exhaust ports 60 has been designated in Figure 3 as station D, and in Figures 4 and 5 as stations D and D", respectively. In Figure 3 the angle COD is equal to about 28, in Figure 4 the angle COD is equal to about 13, and in Figure 5, the angle COD" is equal to 0.

The position of the primary exhaust 60 at station D" in Figure 5 coincides with station C, and is that of a normally balanced reversible motor as conventionally employed by the prior art. Such location is at a point midway between stations A and B on the opposite side of the stator 12. Assuming that the port 52 at station A is employed as an air inlet'and that the port 54 at station-B is employed as a secondary exhaust, forward rotation of the rotor 14 will be effected when air is delivered. As the .air acting on the extended vanes efiects forward or clockwise turning of the rotor 14, a certain volume of air will be trapped between adjacent vanes, as indicated at X. Because of the difierence in the exposed area of the two adjacent vanes bounding the volume X, there is a force differential exerted by the air pressure which tends to continue rotation of the rotor 14 in a clockwise direction, and as it does so the volume X continuously expands in size until it reaches the point of exhaust at the midway station C-D". As the rotor 14 continues to turn beyond the midway station, a quantity of air at exhaust pressure is trapped between the same pair of adjacent vanes as indicated at Y, and is compressed as the volume continuously decreases in size.

The compression volume Y communicates with the secondary exhaust port 54 at station B, where the entrapped air is permitted to escape to the atmosphere, thereby completing a pumping cycle for the volume bounded between the adjacent vanes. When the expansion volume X travels between stations A and C, the air entrapped between the adjacent vanes performs work on the rotor. When the compression volume Y travels between stations C and B, the rotor necessarily performs work on the air. Consequently, by shifting the primary exhaust location clockwise from station C, it is possible to lengthen that portion of the cycle during which the air does work on the rotor and correspondingly shorten that portion of the cycle during which the rotor must do work on the air. In this manner, it is possible for the motor construction of the present invention to provide greater power in its forward direction of rotation than in its reverse direction of rotation. Such an arrangement may be termed an unbalanced reversible motor.

I'have found that the ratio of forward power to reverse 4 power is dependent upon the positive. angle "of'ofi-set within the range of from greater than 0 to 28, with a variation of a few degrees on either side of the upper 28 limit. In Figure 4 of the drawing, I have illustrated an angular displacement COD of about 13. The angular displacement COD of about 28 shown in Figure 3 represents the optimum location of the primary exhaust. The arrangements of Figures 4 and 5 are intended primarily for purposes of illustrating comparative performances. v

- As best seen in Figure 3 of the drawing, the area of communication between the

air inlet ports

52 and 54 and the fluid volumes confined between the adjacent rotor vanes is increased by cut-away portions 62 and 64. In particular, the cut-away 64 approaches the primary exhaust 60 so as to provide a length of internal surface therebetween which is approximately equal to p the circumferential spacing between the vanes in contact therewith, thereby preventing any substantial compression therebetween during forward operation. The size of the cut-away portions 62 and 64 shown in Figure 3 will, of course, vary depending upon the number of vanes and their circumferential separation, but the particular 28 angle of olfset from center for the primary exhaust ports 60 is independent of the size and spacing of the vanes.

In Figures 6, 7, and 8, I have plotted various performance parameters to illustrate the comparative operation of the arrangements illustrated in Figures 3, 4, and 5,

respectively. The graphs of Figures 6 to 8 include plots of H. P., R. P. M, and air consumption against torque, for both forward and reverse rotation of the various motor constructions. These graphs have been plotted from information obtained by dynamorneter tests on each of three rotor cylinders corresponding to the primary exhaust locations of Figures 3 to 5. All other motor parts were maintained identical for the data-obtaining tests. The stator of Figure 3 provides the data of Figure 6, and stator of Figure 4 provides the data of Figure 7, and the stator of Figure 5 provides the data of Figure 8. The following information can be derived from the graphs:

00 0 Parameter Balanced Unbalanced Unbalanced Max. H. P., Forward 1. 09 I 1. 25 1. 46 Max. H. P., Reverse 1. 09 .87 .78 Free Speed, Forward 3, 800 4, 300 5, Free Speed, Reverse 3, 900 3, 300 3, 150 Air Consumption at Max. H.

' P P., Forward 42 38 31 It will be seen from the above table that 'a shift of 28 in the ofiset location of the primary exhaust serves to increase the maximum H. P. for rotation in a forward direction by 0.37, while the corresponding decrease in reverse H. P. is only 0.31. It is also apparent that the free speed forward for the same two cylinders has been increased by 1350 R. P. M. while the free speed reverse has been decreased only 750 R. P. M. A further ad vantage will be apparent in the increase in operating efficiency in a forward direction by comparing the value of 42 cu. ft. of air per developed H. P. for the balanced arrangement to only 31cu. ft. of air per developed H. P. for the28 offset arrangement.

It will be apparent that by shifting the primary exhaust ports 60 off-center to obtain the desired unbalanced power in forward and reverse operation, there. has been a greater gain in power on the forward "side than is lost on the reverse side. I have found that the optimum angle of displacement is that which is suflicient to effect 'a diiferential in H. P. in the forward and reverse direc- 28 offset location provides the approximately 2:1 differential of 1.87,

Changes may be made in the construction and arrangement of the parts of my motor construction without departint from the real spirit and purpose of my invention, and it is my intention to cover by the claims any modified forms of structure or use of mechanical improvements which may be reasonably included within their scope.

What I claim as new and desire to obtain by Letters Patent of the United States is:

1. A reversible fluid motor comprising a stator having a bore defining a continuously curved internal surface, a rotor eccentrically disposed within said bore in bearing contact with said internal surface to define an elongated fluid chamber of synmmetrically increasing cross section from a minimum area at the ends thereof to a maximum area midway therebetween, said stator having a pair of ports communicating with said chamber at opposite ends thereof closely adjacent said portion of rotor bearing contact, one of said port providing an inlet during forward rotor rotation and a secondary exhaust during reverse rotor rotation and the other of said ports providing a secondary exhaust during forward rotor rotation and an inlet during reverse rotor rotation, and said stator having on only one side of said maximum chamber area a third port communicating with said chamber intermediate said pair of ports and closer to said other of said ports than to said one of said ports to provide the only primary exhaust from said chamber.

2. A reversible fluid motor comprising a stator having a bore defining a continuously curved internal surface, a rotor eccentrically disposed within said bore in bearing contact with said internal surface to define an elongated fluid chamber of symmetrically increasing cross section from a minimum area at the ends thereof to a maximum area midway therebetween, said stator having a pair of ports communicating with said chamber at opposite ends thereof closely adjacent said position of rotor bearing contact, one of said ports providing an inlet during forward rotor rotation and a secondary exhaust during reverse rotor rotation and the other of said ports providing a secondary exhaust during forward rotor rotation and an inlet during reverse rotor rotation, and said stator having on only one side of said maximum chamber area a third port communicating with said chamber intermediate said pair of ports and closer to said one of said ports than to said other to provide the only primary exhaust from said chamber, the location of said primary exhaust being sufficiently unbalanced to one side of said maximum chamber area to effect a diiferential in power in the forward and reverse directions substantially equal to 2 to 1.

3. A reversible fluid motor comprising a stator having a bore defining a continuously curved internal surface, a rotor eccentrically disposed within said bore in bearing contact with said internal surface to define an elongated fluid chamber of symmetrically increasing cross section from a minimum area at the ends thereof to a maximum area midway therebetween, said rotor having a plurality of circumferentially spaced vanes radially slidable to etfeet contact with said internal surface and divide said chamber into adjacent volumes, said stator having a pair of ports communicating with said chamber at opposite ends thereof closely adjacent said position of rotor hearing contact, one of said ports providing an inlet during forward rotor rotation and a secondary exhaust during reverse rotor rotation and the other of said ports providing a secondary exhaust during forward rotor rotation and an inlet during reverse rotor rotation, and said stator having on only one side of said maximum chamber area a third port communicating with said chamber intermediate said pair of ports and closer to said one of said ports than to said other to provide the only primary exhaust from said chamber, whereby that portion of said chamber wherein said adjacent volumes increase in size for expanding fluid from the inlet toward the area of maximum chamber cross section is of greater length during forward rotor rotation and of lesser length during reverse rotor rotation than the remaining portion wherein said adjacent volumes decrease in size for compressing fluid from the area of maximum chamber cross section to the secondary exhaust.

4. A reversible fluid motor comprising a stator having a cylindrical bore therein, a rotor of smaller diameter than said bore eccentrically disposed within said bore in contacting engagement with said stator to define a hearing seat and a partial annular chamber extending from one side of said seat to the other, said chamber being of minimum cross-sectional area at opposite ends thereof adjacent said seat and symmetrically increasing in cross section from each side of said seat to a maximum area directly opposite said seat, said stator having a pair of ports communicating with said chamber at opposite ends thereof closely adjacent said bearing seat, one of said ports providing an inlet during forward rotor rotation and a secondary exhaust during reverse rotor rotation and the other of said ports providing a secondary exhaust during forward rotor rotation and an inlet during reverse rotor rotation, and said stator having on only one side of said maximum chamber area a third port communicating with said chamber adjacent said area of maximum cross section and offset from said area of maximum cross section toward said one of said ports to provide the only primary exhaust from said chamber.

5. A reversible fluid motor according to claim 4, wherein the offset location of said primary exhaust is at an angle with the axis of said rotor, formed between radii passing through said area of maximum cross section and said primary exhaust, of about 28 6. A'reversible motor according to claim 4, wherein the ofiset location of said primary exhaust is at a positive angle with the axis of said rotor, formed between radii passing through said area of maximum cross section and said primary exhaust, of from greater than 0 up to about 28".

References Cited in the file of this patent UNITED STATES PATENTS