US2811928A - Rotor vane control - Google Patents

Description

Nov. 5, 1957 G. W. DEAN 2,811,928

ROTOR VANE CONTROL Filed Jan. 4, 1956 2 Sheets-Sheet l ATTORNEYS Nov. 5, 1957 G. W. DEAN 2,811,928

ROTOR VANE CONTROL Filed Jan. 4, 1956 2 Sheets-Sheet 2 INVENTOR @new if a/m/ @www ATTORNEYS nited States Patent O ROTOR VANE. CONTROL George W. Dean, Pittsburgh, Pa., assiguor to Rockwell Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Application January 4, 1956, Serial No. 557,319

3 Claims. (Cl. 103-143) This invention relates to improvements in rotary meters, motors, pumps and like devices of the positive displacement type and particularly to vane movement controls in such devices.

The invention in its preferred embodiment will be described as applied to the positive displacement type device disclosed in Farrell Patent No. 2,694,983 issued November 23, 1954, which embodies a casing having a measuring chamber Within which a rotor is journalled, the rotor having a plurality of peripheral recess pockets within which are rotatably positioned vanes that move with the rotor about the rotor axis but are controlled to always face in the same direction.

The Farrell patent discloses a rotor vane control Wherein individual crank arms of predetermined length on the individual vanes are operably connected to a common control plate of predetermined eccentricity with respect to the rotor axis so as to effect the desired positional control over the vanes. In Farrell the crank passing the division plate during rotation of the rotor is located to extend generally perpendicularly to the chord of the division plate, and the other cranks are all parallel to it. In order that this arrangement be workable it is required that quite close tolerances` be maintained in the dimensions and connections between the control plate, the crank and the vane shafts to hold the vanepassing the `division plate against tipping out of its pocket to strike the division plate as the rotor turns. It is extremely dillicult, and almost impossible in production, to attain. such accuracy of dimensions. It has been found that even when the crank and eccentric dimensions conform to expected good machine practice tolerances, it is necessary to allow some small movement of the pin on the control member in the crank arm in a direction parallel tothe length of the crank arm because if that isA not done the accumulation of these manufacturing tolerances could cause 'binding of the crank arm connections. Now if the crank arms of the Farrell patent were slotted in the direction of their length enough to permit the movement arising from expected manufacturing tolerances such would result in a lag of the control member position of revolution with respect to the rotor. This would lcause each vane totip about its axis an amount equal to the ratio of the effective crank arm length to the radius of the semi-cylindrical vane surface multiplied by the control member lag, and this tipping occurs as the vane passes over the division plate where it is most important tovprevent such tipping.

According to the present invention it has been discovered that desirable play or lost motion to prevent binding in the vane control mechanism can be provided in such devices and at the same time retain the necessary precise control of vane position by providing crank arms extending between the vane shafts and the control plate in a direction that is substantially parallel to the division plate chord and parallel to the diametral plane containing the opposite straight side edges of the semi-cylindrical surface of the vane, which` positionj is substantially perpendicular to the crank position of the Farrell patent.

Patented Nov. 5, 1957 ICC ' held to a minimum as the vanes successively pass the division plate of the meter, motor or the like.

A further object of the invention is to provide a novel rotor vane control wherein adequate lost motion is permitted to prevent binding of the crank pivots but wherein said cranks are so oriented that vane tip due to such lost motion is minimized as the vane moves past the division plate during movement of the rotor.

It is a further object of the invention to provide a rotor vane control wherein an eccentric arrangement is connected by cranks to the vanes on the rotor to maintain them similarly oriented as the rotor turns about its axis characterized by the fact that each rotor has a semicylindrical surface and its crank extends parallel to a diametral plane containing the opposite straight side edges of that surface, all of the cranks retaining parallelism during operation.

Further objects of the invention will appear as the description proceeds in connection with the appended claims and the annexed drawings wherein:

Figure l is a section through a positive displacement meter according to a preferred embodiment of the invention showing the crank connections of the vane shafts to the control member;

Figure 2 is a section on line 2 2 of Figure l showing the control member mounting and the division plate;

Figure 3 is an enlarged cross section of a crank used in Figures l and 2;

Figure 4 is a top elevation of the crank of Figure 3;

Figure 5 is a fragmentary section showing the relative vane positions; and Figure 6 is a fragmentary view showing an optional open-ended crank.

The disclosed meter comprises a casing 11 housing a cylindrical walled measuring chamber 12 with Huid inlet port 13 spaced from outlet port 14 by a division plate 15 xed to the casing as by one or more bolts 16. Within the casing rotor 17 which comprises a solid body 18 having a cylindrical peripheral surface flanked by side members 19 and 21 secured thereto as by bolts 22 and 23, respectively, is mounted for almost frictionless rotation in concentric ball bearings 24 and 25. A stub shaft 26 rigid with side member 21 is mounted in bearing 25 carried by casing end closure plate 27. Coaxial drive output shaft 28 is mounted in bearing 24 carried by an internal web 29 of the other casing end closure 31. The cylindrical inner surface 60 of the division plate 15 has a running lit with the cylindrical periphery of rotor 18.

Rigid with shaft 28 is a small gear 32 connected through a gear train 33, 34 and 35 to a register drive shaft 36. This drive is conventional.

Shaft 28 extends freely rotatably through the cylindrical bore 37 of a control eccentric element 38 which has an external cylindrical surface 39 eccentric to shaft 2S. Element 38 is xed to the meter casing as by one or more screws 41 securing it to web 29.

An annular vane control member 42 is rotatably mounted on eccentric surface 39 by a ball bearing assembly 43, the inner race 44 of which is 'fixed to ec` centric 38 as by force tit and the outer race 45 of which is fixed within annular member 42 as by force t. The bearing assembly 43 is maintained against axial shift on eccentric 38 by contact with web 29 on one side and an integral flange 46 on the eccentric overlapping inner bearing race 44 on the other side.

With reference to Figure 5, the rotor body has four circumferentially equidistantly spaced peripheral pockets 47 the opposite sides of which are closed by the parallel flat inner surfaces of rotor side members 19 and 21. Rotor shaft sections 48 are parallel to the rotor axis and coaxially journalled at opposite ends of each pocket 47 in bushings 49 as shown in Figure l. A semi-cylindrical surfaced vane 51 is fixed on and between the rotor shaft sections 48.

One rotor shaftsection 48 of each vane extends into the closure 31 as shown in' Figure 2 and is further reduced as indicated at 52 for mounting a` crank arm 53. As shown in enlarged Figure 3, shaft end 52 has a side flat 54 and fits within a similarly shaped bore 5S at the bottom of the split end of crank arm 53, and when bolt 56 is tightened the crank arm is fixed rigidly on the end of the vane shaft 48 in a predetermined angular relation with respect to the vane.

A plurality of circumferentially equidistant cylindrical pins 57 are fixed on control member 42 to project axially toward the rotor and enter the aperture 58 in each crank arm 53. Apertures 58 have a width equal to the diameter of pins 57 for smooth sliding fit with pins 57 longitudinally of each crank arm and a length greater than the diameter of pins 57 to provide lost motion for a purpose to appear. lf desired the aperture 58 could be opened all the way to the right end of the crank arm 53 of Figure 3 without departing from the spirit of the invention, as shown in Figure 6.

The distance between the center of each vane shaft 48 and its adjacent pin 57 is effectively equal to the distance that member 38 is eccentric to shaft 25, for a purpose to appear.

Figures 2 and 5 show the parts in their relative operational positions when one vane 51 is passing the division plate during rotation of the rotor. As fluid enters at 13 it strikes the vane 51 at the upper right in Figure 5 and the rotor 18 is turned about its axis thereby carrying with it all of the vanes. As the rotor turns the crank arm connection of the vanes with rotatable control member 42, which rotates with the rotor, maintains each of the vanes 51 in the same orientation with respect to the division plate, with crank arms 53 and vanes 51 rocking 90 in the same direction in every quadrant and arms 53 always maintaining parallelism. The spaces between the three vanes projected into the measuring chamber 12 are in effect sealed so that the same volumes of liquid are released to the outlet 14 as the rotor turns through each 90 and the register driven shaft 36 indicates volume in proportion to rotor turns.

Each vane has a semi-cylindrical peripheral surface 65. In the invention each of the parallel crank arms 53 always extends in the same direction which is substantially parallel to the diametral plane of the surface 65 that contains the opposite parallel straight edges 59 of the respective vane surface.

As shown in Figures 2 and 5, the inner surface 69 of the division plate is of cylindrical contour about the axis of shaft 23, and the opposite edges 59 of the vane passing are maintained substantially parallel to a chord perpendicular to a radial plane bisecting that surface to avoid striking it as the rotor rotates.

In the invention where the crank arms 53 are disposed parallel to the diametral plane of the vane surface as described, the maximum vane tipping occurs in the vane extended positions 90 from the division plate where such tipping it not as critical as at the division plate. The amount of vane tipping at the division plate position is equal to the ratio of effective crank arm length to the vane surface radius times the segment height of the pin 57 in moving from the true center to the side of the elongated aperture 58, and in practice has been found to amount to about only one one-hundredth of that which would be permitted if the crank arms 53 were oriented as in the Farrell patent.

The invention therefore permits larger machine tolerances in the manufacture of the eccentric and the crank arm connections, and results in longer meter life because greater wear can be permitted in the mechanism and bearings before the vane tipping becomes so large that the vane edge will strike the division plate during turning movement of the rotor.

Figure 6 shows another form of crank that may be used on the vane shaft 52. Here the crank 6i is fixed to shaft 52 as by pin 62 and the end of the crank is formed with a rectangular slide slot 63 which slidably receives a crosshead 64 in which is journalled the control pin 57.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to bc considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meanand range of equivalency of the claims are therefore ended to be embraced therein.

What is claimed and desired to be secured by United States i4etters Patent is:

l. In combination, a casing having an internal cylindrical surface, a rotor mounted for rotation in the casing provided with a cylindrical external peripheral surface concentric with and radially spaced from said casing surface and forming therewith an annular fluid displacement chamber and having a plurality of axially extending equidistantly spaced peripheral surface pockets, a vane mounted in each pocket for rocking movement about an axis parallel to the rotor axis, said vanes being adapted to project into said chamber and each vane having a semi-cylindrical surface with diametrally opposite side edges parallel to the vane axis, a division plate mounted in said chamber in running clearance with said rotor surface, inlet and outlet ports to said chamber on opposite sides of said division plate, an annular control member mounted in said casing for free rotation about an axis parallel to but eccentric from said rotor axis, and a crank extending between each vane and corresponding equidistantly spaced points on said control member, means securing each crank toits associated vane so that the crank extends longitudinally in a direction substantially parallel to the diametral plane of the vanesurface that contains said diametrally opposite side edges, and means providing a substantially linear slide pivot fit between each crank and said control member.

2. In combination, a casing having an internal cylindrical surface, a rotor mounted for rotation in the casing provided with a cylindrical external peripheral surface concentric with an'd radially spaced from said casing surface and defining therewith an annular fluid displacement chamber and having a plurality of axially extending equidistantly spaced peripheral surface pockets, a vane mounted in each pocket for rocking movement about an axis parallel to the rotor axis, said vanes being adapted to project into said chamber and each vane having a semicylindrical surface with diametrally opposite side edges parallel to the vane axis, a division plate mounted in said chamber in running clearance with said rotor surface, inlet and outlet ports to said chamber on opposite sides of said division plate, an annular control member mounted in said casing for free rotation about an axis parallel to but eccentric from said rotor axis, and a crank extending between each vane and corresponding equidistantly spaced points on said control member, means rigidly securing each crank to its associated vane so that the crank extends longitudinally in a direction substantially parallel to the diametral plane'of the vane surface that contains said diametrally opposite side edges, and means providing a slide pivot fit between each crank and said control member comprising fixed pins axially projecting from said control member and slidably received in longitudinally extending apertures in said cranks.

3. A fluid handling device of the positive displacement type comprising a body made up of a housing having an inner cylindrical surface therein and opposed rigid end members, a rotor rotatably mounted on the axis of said rotor and having an external cylindrical surface concentric with and radially spaced from lthe inner cylindrical surface of -said housing to form an annular fluid displacement chamber, -spaced end members fixedly mounted on said rotor having a running clearance with the body t0 close the ends of said displacement chamber, 'a division plate mounted in said chamber on the inner surface of said housing and having a running clearance with said rotor, means providing lluid inlet and outlet connections in said chamber adjacent opposite sides of said division plate, a plurality of longitudinal surface pockets in said rotor extending between said end members, a vane shaft rockably mounted about an axis parallel to the rotor axis within each surface pocket projecting through one of said rotor end members, a vane having a semi-cylindrical surface with diametnally opposite side edges parallel to the vane shaft axis mounted on each of said vane shafts within said pockets, means for rotating the vanes in timed relation with the rotation of the rotor so that each vane withdraws within its pocket as it passes the division plate comprising a vane position control member mounted for 20 2694983 free rotation on the housing end member adjacent one rotor end member and on an axis that is parallel to the rotor axis but displaced radially therefrom by a predetermined distance, cranks rigidly connected to each of said vane shafts to extend longitudinally substantially parallel to a chord of the vane surface, each of said cranks extending in the same direction from its shaft and substantially parallel to a diametral plane that contains said side edges, a plurality of axially projecting equidistant circumferentially spaced pins on said control member slidably litting into longitudinal slots in said cranks and said cranks each having an effective working length substantially equal to said predetermined distance whereby the orientation of each vane about its axis remains substantially fixed with respect to the housing as the vane axes move the rotor axis.

References Cited in the ile of this patent UNITED STATES PATENTS 153,202 Pruett July 21, 1874 1,565,401 Schaeren Dec. 25, 1925 2,508,356 Allsup May 23, 1950 Farrell Nov. 23, 1954 FOREIGN PATENTS 187,357 France Dec. 6, 1887 480,856 Great Britain Feb. 25, 1938 988,951 France May 16, 1951

Images