US 3135499 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
United States Patent O 3,135,499 MATERIAL MIXING AND DSPERSING APPARATUS Donald J. Brown, La Crescente, Calif., assignor to The Cowles Dissolver Company, Inc., Cayuga, N.Y., a corporation of New York Filed `luly 1, 19,59, Ser. No. 824,359 1 Claim. `(Cl. 259-435) The present invention relates generally to a mixing and dispersing device, and is more particularly concerned with such a device as may be utilized for the dispersion, deagglomeration, dissolving and disintegration of synthetic, organic and inorganic solids in liquid, liquids in liquid, and gas in liquid.
` The heretofore available mixers of the type described herein, such as commercially available for batch mixing of liquids, solids, gases and the like have in general been uneconomical of operation at relatively low mixing speeds, and have not had sufficient driving power at these low speeds to permit high production operations. Direct speed reductions from the motor speed to the required low impeller speed through the use of a variable speed transmission results in loss of power and consequent inefciency. The size of batch which can therefore be handled must be reduced.
Many mixers of this character are used for introducing solids into liquids, and it has been found that in order to accomplish such operation onan economic production basis at relatively low speeds, high power .output is required.
Having in mind-the foregoing, the present invention proposes to provide an arrangement wherein the speed dominating at portion of the conventional transmission speed-horsepower curve at which position the power is mostefticiently transmitted, and thereafter reducing the speed thus obtained, by a predetermined iixed ratio of speed reduction with only slight loss of efliciency.
A further object of the invention resides in the provision of conveniently operable mechanism for controlling and varying the driven speed of the mixing elements in such a manner as to more efficiently obtain the high power output at a relatively low speed.
Another object is to provide a driving connection in mixersy of the herein described type, wherein the drive between the power source and the mixer element will be accomplished between short shaft centers so as to reduce and minimize the effect of harmonics. Y
Still another object lis to provide mixing apparatus wherein the parts are supported on a pedestal in balanced relation, and which incorporates a uniqueV arrangement enabling, raising and lowering movements for placing the mixing elements in position of use and non-use.
Further objects will be brought out in thegfollowing part of the specication, wherein detailed description is for thepurpose of fully disclosing the apparatus.
FIG. 4 is a detail fragmentary view showing the speed adjusting handv wheel arrangement, taken substantially on line 4 4 of FIG. 3; and
FIG. 5 is a graph representing the method of speed reduction, as utilized in the present invention.
Referring more specifically to FIG. 1 of the drawings, for illustrative purposes the apparatus is shown as comprising generally an upstanding pedestal structure 10 at the top of which is a transversely extending housing structure 11 which cooperates with the pedestal structure to form in effect a T-structure. The housing 11 projects on opposite sides of the pedestal axis, a driving electric motor 12 being supported on one side of the pedestal from the housing structure, while on the opposite side of the pedestal there is provided a depending vertical shaft 13 which carries an impeller disc 14 at its lowermost end, this irnpeller disc being fitted on its periphery with a plurality of blades 15 for processing specific materials, the impellers being interchangeably connected to the shaft.
It will be observed that with the T-structure explained above, a balanced arrangement is provided wherein the motor 12 is in counterbalanced relation to the impeller shafty 13 and other mechanism on the opposite side of the pedestal 10. The housing 11 with the motor 12 and irnpeller shaft 13 are associated as a unit which is pivotally supported for rotation about the axis of the pedestal 10, as well as raising and lowering movements with respect to the pedestal, as will hereinafter be explained more fully. The housing 11 and connected parts may be rotated and locked in any desired angular position. A guide rod 16 supported from the housing structure extends in parallel axial relation to the pedestal through a slide connection 17 of a brake band 18 arranged to be operated into clamped and unclamped relation with the pedestal surface by means of a manually operable clamping screw 19.
Speed control of the impeller is obtained through the V actuation of a hand wheel 20 conveniently positioned on the side of the housing structure 11.
The general arrangement of parts as explained above results in a very desirable feature for apparatus of this character in that the operating elements for effecting speed control are contained within the housing 11, while the motor and the impeller shaft extend below the housing, thus leaving a clear space above the housing which is devoid of mechanism which would interfere with overhead or ceiling structures, during raising movements of the device. t
Iportion of the device. The tank 24 is connected through the conduit 25 to the interior of the pedestal-cylinder, and
raising and lowering movement of the device is controlled by suitable valve 26 supported at the top or uppermost end of the tank 24, where it is within easy reach of the operator.
Referring to the accompanying drawings, which are for illustrative purpose only:
FIG. 1 is a perspective view of apparatus embodying the features as described herein;
`FIG. 2 is an enlarged fragmentary view in elevation, the housing being in section to reveal the cooperative relationship ofV the driving elements, and other constructional features of the apparatus;
FIG. 3 is a fragmentary sectional View taken substantially on line 3--3 of FIG. 2;
At its uppermost end, the piston 21 connects with a bridging frame structure 27 which is constructed between its ends with a generally frusto-conical housing portion 28 which is connected with the uppermost end of the positioning longitudinally of the bridging frame`27 to Y The l permit replacing of driving belts of speed transmission means to be hereinafter explained. The driving motor 12, is secured as by supporting bolts 31 to the opposite end of the bridging frame 27, on the opposite side of the pedestal from that of the shaft 13 having the impeller thereon. The motor 12 has a drive shaft 32 positioned so as to project upwardly into the frame structure. Heretofore, in order to take advantage of the balanced frame arrangement in which the motor 1.2 is in counterbalanced relation with respect to the impeller and its actuating shaft, it has been the customary practice to utilize a variable speed direct drive between the motor shaft 32 and the impeller shaft 13. It will be appreciated, however, that in so doing, the arrangement utilizes a relatively long spacing between shaft centers. It is a characteristic of such drives that they have objectionable harmonics so that it is not possible to obtain a desired smoothness of drive. Moreover, it has been found that the use of variable speed drive directly between the motor shaft and impeller shaft results in ineilcient transmission of power to the impeller shaft at its lower operating speeds. For example, with a 20 H.P. electric motor operating at 1890 r.p.m., a single stage reduction of the driving speed by variable transmission connected between the motor and impeller shaft, at approximately 600 r.p.m. at the impeller shaft would theoretically deliver in the order of 11 H.P. as may be seen from a conventional variable transmission speed-horsepower curve A as shown in FIG. 5. Such power reduction is undesirable in many mixing operations and thus curtails economic production.
In the present invention, it is-proposed to overcome the above inherent disadvantages in a single stage variable transmission by the provision of a multi-stage transmission between the motor drive shaft 32 and the impeller shaft 13, wherein short shaft spacings may be utilized, and in which the rst stage constitutes a variable speed transmission connected with the motor shaft 32, which may be operated at a higher low speed.
More specifically, the above is accomplished by providing a countershaft 33 which extends vertically within the housing portion 28 and is supported adjacent its ends in anti-friction bearings 34 and 35. The countershaft 33 projects above the bearings 35 and carries a multibelt pulley 36 adapted to receive a plurality of V-belts 37 which are trained over a multibelt pulley 38 mounted on the upper end of the vertical shaft 13. The pitch diameters of the pulleys 36 and 38 are such as to provide a fixed speed reduction ratio between the speed of the countershaft 33 and the shaft 13.
The countershaft 33 is driven from the drive shaft 32 through a variable speed transmission which includes a driven sheave 39 carried by the countershaft 33, this sheave having an upper half 39a secured to the countershaft, and a lower half 39b supported for sliding movement on the countershaft and biased towards the xed half by means of a compression spring 40. The drive shaft 32 carries a sheave 41 which is composed of a lowerhalf 41a which is xed on the shaft 32, while an upper half 41b of the sheave is slidably movable on the drive shaft and is connected with an adjusting mechanism, as generally indicated at 42, by means of which the upper and lower halves of the sheave 41 may be moved towards and away from each other to change the relative effective diameters of the sheaves comprising the variable speed transmission in a manner well-known in the art, these sheaves being interconnected by a belt 43.
As illustrative of a specific arrangement utilizing the present invention, a 20 H.P. motor operating at 1800 r.p.m. drives the countershaft through the variable speed transmission which may be adjusted to rotate the countershaft at speeds between 877 to 2630 r.p.m. in accordance with curve A as shown in FIG. 5. It will thus be observed that at the lower speed limit, point a on the curve, substantially 16 H.P. will be delivered, and that at the upper speed limit, as indicated at point b, the variable transmission is capable of delivering substantially 28 H.P. although delivery of such power would necessitate operating the motor under overload conditions. The sheave 36 has a 7.4 pitch diameter, while the sheave 38 has an 11" pitch diameter. The speeds of the countershaft are thus reduced to operating speeds for the shaft 13 of substantially 600 r.p.m. to 1800 r.p.m., as shown on curve B of FIG. 5. This speed reduction is made with substantially no loss in efliciency so that at the lower speed limit, indicated at point a', substantially 16 H.P. will be delivered to the shaft 13, whereas at the upper speed limit of 1800, as indicated at point b', substantially 28 H.P. could be delivered; It will thus appear that by the utilization of a multistage speed reduction as described above, it is possible to deliver 16 H.P. at 600 r.p.m. of the shaft 13, as compared to l1 H.P. in the case of direct speed reduction from the motor shaft 32 to the shaft 13.
Referring now to FIGS. 3 and 4, provision is made for manually adjusting the variable speed transmission. For such purpose, the adjusting mechanism 42 is shown as including a cylindrical structure 44 mounted for axial movement with respect to the shaft 32 with the upper half 41b of the adv/jacent sheave, but enabling relative rotating movement between the cylindrical structure and the upper half 41]?. The structure 44 is pivotally connected at diametrically opposite pivot points 45 and 46 to spaced arms 47 and 48 of a yoke member 49 which is rockingly supported on upstanding bearing brackets 50 and 51. On the opposite side from the arms 47 and 48, the yoke has a single projecting arm 52 which extends through a side wall opening 53, the outermost end of the arm 52 being positioned over the uppermost end of a rod 54 rotatably supported in spaced bearings 55 and 56 of a bearing bracket 57 secured to the bridging frame 27 The uppermost end of the rod 54 is threaded for engagement with internal threads formed in the bearing 56 so that upon rotation of the rod, as by the hand wheel 20, the rod will be axially moved so as to vary the position of the arm 52 and the consequent adjustment of the sheave 41 to provide the desired change in speed between the shaft 32 and countershaft 33 to effect the desired operational speed of the shaft 13.
In order to indicate the adjustment of the variable speed transmission, the shaft 54 is shown as carrying an indicator 59 which is longitudinally movable in response to movements of the rod 54 in a slot 60 formed in a closure casing 61.
Various modifications may suggest themselves to those skilled in the art without departing from the spirit of my invention, and, hence, I do not wish to be restricted to the specic form shown or uses mentioned, except to the extent indicated in the appended claim.
In material mixing and dispersing apparatus: a frame; an impeller on a driven shaft carried by the frame; an electric motor power device with a drive shaft operable at a substantially constant speed; a two-step transmission comprising a fixed ratio speed reducing transmission drive in which a plurality of V-belts interconnect V-shaped grooved pulleys on the driven shaft with V-shaped grooved pulleys on a countershaft, and a variable speed ratio transmission drive operable to drive the countershaft from the drive shaft a speeds above and below the drive shaft speed and having a substantially at speed-power curve for countershaft speeds above said drive shaft speed, said variable speed transmission comprising V-pulley forming sheaves carried by the countershaft and normally being spring biased towards each other and towards a position of maximum effective diameter, other V-pulley forming sheaves carried by the drive shaft and supported for relative movements towards and away from each other, a V-belt trained over the V-pulleys formed by said sheaves and normally maintained under tension by said spring, the effective diameters of the sheaves on such shafts being delatively so proportioned that the countershaft may be driven in a speed range extending above the speed of the drive shaft and deliver substantially constant horsepower output; and manually operable means adjustable to vary the eifective diameter of the V-pulley forming sheaves on the drive shaft and through said associated tensioned belt to inversely vary the effective diameter of the V-pulley forming sheaves on the countershaft, whereby the xed ratio transmission drive will operate to transmit delivered horsepower at selective speeds of the countershaft at correspondingly lower speeds of the driven impeller shaft speed range as determined by the fixed ratio transmission drive.
References Cited in the le of this patent UNITED STATES PATENTS 2,267,238 Irwin Dec. 23, 1941 6 Hishon et al. Oct. 16, 1945 Dubin Sept. 13, 1949 Salsbury et a1. Nov. 14, 1950 Krafka Apr. 24, 1951 Felix Dec. 2, 1952 Feustel May 12, 1953 Courtney Sept. 8, 1953 Oehrli May 18, 1954 Beam Oct. 29, 1957 FOREIGN PATENTS Australia May 27, 1935 Germany July 16, 1942