Improvement in botary blowebs
US 81009 A
Description (OCR text may contain errors)
P. H. &--'F. M. ROOTS. ROTARY BLOWER Patented Aug.'11,' 1868.
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P. H. ROOTS AND F. unoors, or CONNL-ERSVILLE INDI'A'NA.
Letters Patent No. 81,009, dated August 1 1, 1 868.
\ IMPROVEMENT IN ROTARY BLOWERS.
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TO .ALLLWHOM IT MAY CONCERN: v I
f Be it known that we, I. H. ROOTS and F. M. Rows, of Conncrsville, in the county of Fayette, and State .of- Indiana, have invented a new and improved Rotary Blower; and we do hereby declare that the following is a full',.clear, and exact description thereof, which will enable others skilled in the art to make and use the same,
reference being bad to the accompanying drawings, forming a part of this specification, in which- .r-Figure 1 represents a vertical transverse section of our rotary blower.
Figure 2 is a sectional view of two abutments, showing their relative positions as they'have hitherto been made, and the source of the difficulty hitherto experienced.
Similar letters of reference indicate corresponding parts.
This invention relates to a new manner of constructing the abutmcnts in that class of rotary blowers or engines in which two rcvolving abutments are used, whose circular portions or peripheries are formed of arcs of difi'erenFdiamefrsQ i invention relates also to constructing the abutments with'shell-pistons, each having one or more arms or wings extending from the centre cylinder to the outer circular part of the piston, which is either cast on the armsor otherwise secured to themin the proper manner, whether made of metal or, wood. Thesearms or wings extend the entire length of the cylinder, thus forming a sort of continuous cross-head. I
This invention consists, further, in constructing the centre cylinder, of plaster of Paris or'other material. in
a plastic or molten state.
This invention consists, finally, in forming the pistons of such proportions, by suitably reducing their arcs and increasing correspondingly the recesses, as will overcome difiiculties experienced in former methods of construction. Y
The objcct of this invention is to construct the abutments of rotary blowers, of sufliciently lightweight to adapt them't'o run at such speed as is necessary to force any considerable volume of air, and at the sometime so to dispose of the metal as to secure adequate strength, and also to construct them either partly of wood or entirely of metal. I
And, finally, the object of this invention is so to proportion the pistons and recesses as to obviate difiicu'lties ,which have rendered machines made as described in the Letters Patent granted to us, January 21, 1868, (No.
73,654,) almost useless. V
-A B are twocoacting, rotating abutments, mounted on two shafts, G G. Each abutment consists of two pistons, a a, and two intervening recesses, 11 b, and a centrc cylinder, c c, as shown in fig. 1. The peripheries of the abutments are formed in the same manner as described in the Letters Patent above referred to, with exceptions that will be noted.
From two points, 0 C, which are the centres of the shafts, and taken at any desired distanccapart according to the size of the machine to'be constructed, are described two circles, c c, ofequal radii, each of .which may be about one-fourth the distance the centres C C are apart. These circles may, howevcr,bedcscribed with a radius greater or less than thathore stated, and may also be made operative with unequal radii, ifidesirecl. The circles c c constitutethe centre cylinders of the abutments. The radius for forming the pistons is the distance from the centre of one of these circles c c to the nearest point in the peripherypf the other 'cii'cle. Of thegperipheries of each of the circles d d" thus formed, two arcs, of'about eighty degrees, are taken on opposite sides of the circle, and the corresponding recess will. consist of gone hundrcd' degrees, whereas in the former patent, both the piston and the recess consisted each of ninety degrees.
Abutments may also be advantageously made for various purposes, unlike each othcra For instance, the
pistons of one abutment may consist of arcs of fifty degrees, instead of sixty, and its recesses of one hundred aiid thirty degrees, instead of one hundred and twenty, and the corresponding abutment will require its pistons -to be one hundred and ten degrees, instead of one hundred and, twenty, a.nd its reccssesconsist oilscvcnty instead of sixty'degrees.
s oes 2 The importance of the object gained by thus shortening the arcs of the pistons will' be readily understood by reference to fig. 2, which represents the position of the abutments when the tips of two pistons are at the I same time in contact with the centre cylinders. This position occurs four times to each revolution of the abutmcnts together. As the pistons approach or reach this position, a violent concussion is produced by the sudden compression of the air caught in the elliptical recess '0, shown in fig. 2, from which recess, for'a brief portion of the revolution of the parts, there is no escape for the air. Soviolcnt is this concussion, that the noise produced by it with a blower running at a moderate speed, can be heard a quarter of a mile or more, thus rendering the machine intolerable and inadmissible in a work-shop or foundry, as conversation would be impossible near the machine. When more dense fluids, as water, are acted upon, the 'ditliculty experienced is still greater.
A pump made with pistons and recesses of ninety degrees can, under any circumstances, move only with a jerking and irregular motion, causing great strain to the maehine, and attended with great loss of power, and if made strictly accurate and tight, is not an operative machine. It has been by numerous and expensive experiments that the seat of the difiiculty'has been ascertained and the remedy devised. When the-abutmcnts, in the course of their revolution, come to occupy the relative position shown in fig. 2, a line drawn through the centre of any one piston to the centre of the opposite piston, forms an anglc'offorty-five degrees with a line drawn from the centre of one shaft, 0, to the centre of the other shaft, 0. In this'ppsition the tips of the two pistons are at the same time iii contact with the two centre cylinders, and form'betwccn them an elliptical '--recess, shown at 'u, fi 2. As the oistons a roach this ositio h, the air is violentl com ressed, and on reach- &' 1 PP P E P ing this position, there is no escape for the compressed-air, as the tips of the pistons are respectively iii' icontact with the centre cylinders. In order to obviate this difiiculty, it is found necessary to prevent this double contact. By removing a portion of the tips of the pistons, an opening or outlet is formed for the air, so that when the pistons come into the position stated above, the tipsof both pistons are disconnected from their respective centre cylinders, until the described position is passed. Asthe air finds an escape through the openings thus formed, the concussion'is thus avoided.
- By reducing the arc ofthe piston about ten degrees, nearly allthe noise and concussion of the air is obviated. This reduction can be varied according to the density of the fluids acted upon, and for dense fluids should be increased to fifteen or twenty degrees; It is evident, also, that by reversing the application of the principle, and removing a portion of the centre cylinder, as indicated by the red lines at a: w, an escape may be made for the air caught in the recess 11. But as the motion of the surface of the centre cylinder is so much slower than that of the pistons, the opening thus formed would not be so instantly closed when no longer needed to be opened, yet the object is well accomplished by this arrangement.
I The construction of the shell-pistons and centre cylinders is clearly shown in fig. 1. .In the abutment A, one piston is constructed with one arm or wing, c, extending from the centre cylinder to the outer circle, a, of the piston with which it is cast. The other piston has two arms, to which the outer circular part of the piston a is cast. The centre cylinder, c, is made of plaster of Paris, or other plastic or molten material, and is held in position by suitable projections, We usually cast the plaster of Paris in a mould to its exact dimensions. Any cheap metal, as zinc, could be substituted and cast in like manner.
In the abutment B, each piston has one arm, with suitable projections or flanges, n 12., at their extremity,to which wood or suitable material is fastened by belts or screws, to form the external circular parts of the pistons. The centre cylinder is formed of wood, fastened with screws or bolts.
, We are thus enabled to construct the abutments of sutiiciently light weight toadapt' them for the purpose of blowers, and at the same time, with accuracy and all necessary strength. These abutments are made to co-operate together by two equal-sized cog-whecls.
In fig. 2, we show a cross-section of the abutrnents of a blower, substantially as they have been hitherto constructed.
The air confined in the elliptical space, and having no means of escape for a certain length of time, is the cause of the difiic'ulty experienced, and which 'is inseparable from blowers or pumps constructed with pistons whose arcs are ninety degrees. It is true that we can in a measure overcome the difficulty, and give relief by cutting grooves the length of the interior cylinders, as shown in a: x, fig. 2, but we prefer to reduce the arc of the piston as described above.
Having described our invention, we claim as new, and desire to secure by Letters Patent- 1. The co-operating abutments A B, constructed with skeleton pistons, having their external circular periphcries connected by'longitudinal arms to the centre cylinders, as and for the purpose specified.
2. The-abutmcnts A B, having their centre cylinders made of plaster of Paris, or other plastic or molten material, substantially as and forfthc purpose set forth.
3. The abutments A B, having the arcs of their pistons so constructed as to become simultaneously disconnected from their respective centre cylinders at certain portions of their revolutions, as herein described.
I. H. ROOTS, F. M.'ROOTS.
Witnesses ALEX. F. Ronnn'rs, WM. F. McNAMAnA.