IMPROVEMENTS IN VENTILATORS OR BLOWERS
Year: 1876

page_text: LETTERS PATENT to Arthur Crespin, of No. 7, Avenue Parmentier, Paris, in
the Republic of France, Civil Engineer, for the Invention of "IMPROVEMENTS
IN VENTILATORS OR BLOWERS."
Sealed the 11th August 1876, and dated the 19th February 1876.
PROVISIONAL SPECIFICATION left by the said Arthur Crespin at the Office
of the Commissioners of Patents on the 19th February 1876.
ARTHUR CRESPIN, of No. 7, Avenue Parmentier, Paris, in the Republic of France,
Civil Engineer.
"IMPROVEMENTS IN VENTILATORS OR BLOWERS."
My Invention consists in improvements in ventilating or blowing apparatus,
the arrangement consisting in the play of two parallel axes provided with arms
in the form of cog wheel teeth, and which in turning in an air-tight casing draw
in the air at one side for forcing it out on the other side. For this purpose I
employ teeth fixed on their respective shafts with a certain amount of play in such
manner as to render them independent of one another within a certain limit, so
that they may have a slight angular movement on each side of their normal
position. By this arrangement it will be understood that two teeth being in
contact, the upper tooth will constantly press on the lower tooth in consequence of
its weight and the difference of the pressure between the air drawn in and the air
forced out. The surfaces of the teeth therefore at their generatrix of contact have
constantly a common tangential plan, thereby insuring a tight joint whatever may
be the wear, the speed, or the pressure of the apparatus.
"
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed by
the said Arthur Crespin in the Great Seal Patent Office on the 11th August
1876.
ARTHUR CRESPIN, of No. 7, Avenue Parmentier, Paris, in the Republic of France.
IMPROVEMENTS IN VENTILATORS OR BLOWERS."
It is a well known fact that two wheels gearing together in an envelope or
cover in which they fit exactly will transport the fluid which surrounds them
from one side of the cover to the other on account of the interval or space between
[Price 6d.]

page_text: cach tooth rising empty on the side where the teeth are not in gear, and
returning full on the side where they are in gear, the teeth fulfilling mutually the
office of tilling up the intervals or spaces in each of these wheels, and con-
sequently transport from one side of this envelope to the other the liquid or
gaseous fluid contained in these intervals or spaces. It is upon this principle
more or less modified that I have acted in producing my rotary machines, pumps,
and ventilators.
.
In all the apparatuses hitherto constructed more or less upon this principle there
has been a great fault of the system itself opposed to the regular working of the
apparatuses. This fault consists in the fact that the tecth of these wheels being all
dependent upon one, another cannot be formed in such a manner as to ensure a
continuous contact with one another during the working. Even supposing their
form to be irreproachable at the commencement, this form wears during the
working, and it results that the joint which may be perfect at the circumference
where packing may be placed is never so at the gearing part, and at any moment
in the passage of two teeth a default of contact at the point of contact of the
wheels will tend to reverse the direction of the working of the wheels, giving a very
bad result for the motor, pump, or ventilator. In the last case the result is
specially palpable, as it only gives a very small charge of water under the ordinary
arrangement, whilst it would give a comparatively unlimited supply if the contact
was continuous.
The object of this Invention is to avoid this fault above described, by making all
the teeth of the wheels in question to a certain degree independent of each other.
In paying great attention to the form of the teeth which are made as much as
possible according to the rules of art, in order to make a perfect joint with the
teeth of the other wheel, I employ the pressure in the top part before and behind
the teeth. In order to obtain this result I employ the arrangement shown in the
Figs. 1, 2, 3, & 4 of the annexed Sheet of Drawings, which I will now proceed to
describe; Figs. 1 & 2 show the principal details of an apparatus; Fig. 3 is a
theoretical drawing which I shall employ for my demonstration.
Two wheels with four teeth or wings each are in gear together. Their perfect
gearing is assured by two wheels mounted upon the same shafts.
These wheels
have comparatively very small teeth which assures the regularity of the relative
angular movement of each of the shafts, from whence it results that my two wheels
of four teeth or wings although as will be seen hereafter not perfectly fixed upon
their shafts, turn constantly whilst in gear as if they were fixed in the most perfect
manner. The teeth of these two wheels; Nos. 1 & 2, are lettered A, B, C, D, E, F,
G, H.
The wheels are enclosed in a cover or box M which is in very close contact
with the circumference of the teeth. This contact is arranged in such a manner
as to determine a certain pressure by means of packing placed upon the extremity
of the tooth, and which forms a perfect joint with the circumference. Each of
these wheels is divided into four equal parts, and each of the teeth or wings is
made as much as possible according to the best rules of art.
The only par-
ticularity is that these teeth or wings are independent of each other, and are
keyed on the shaft with a play of about 1 or 2 millimetres between each.
The direction in which the wheels turn is shown by the arrows, that is, they
ascend to the exterior circumference and descend to the part in gear, which
transports the fluid from h¹ to h. The tooth A of the wheel No. 1 commencing to
rub against the envelope or cover M raises the fluid contained in its interval or
space as well as its own weight; these three resistances determine its momentary
stoppage until the suppression of the two millimetres of play which this tooth
had behind between it and the tooth D, which by its own weight and the charge
which it supports weighs upon it. The tooth D is then also sustained and stopped
at the moment that it crosses the horizontal line N, N¹, and is ready to support
the pressure of the tooth H of the wheel No. 2, which as will be seen has
accumulated in front of it the play of the other teeth of the wheel No. 2, and can
then descend-besides its own movement the whole of the play, its key being behind;

page_text: -
it then results that by its own weight and the pressure weighing upon it, it
forms with the tooth D a very close joint which will be maintained as long as the
part in contact is not worn more than the greatest amount of play.
The teeth B & C of the wheel No. 1 by the rubbing of the circumference
against the envelope or cover raising their own weights and supporting the
difference of pressure & h, have lost all their play behind and have reserved it
in front in such a manner that when the tooth C escapes the envelope or cover M
it will have disposable before it all the play which is now before the tooth H, and
as this tooth H in consequence of the contact at this moment of the tooth E with
the envelope or cover M will have lost the advance which it had, it will be able to
support itself and will form a joint the same as that described between the teeth
H & D. The general principle of working is to stop the teeth at the moment of
crossing the horizontal line by their friction against the envelope, or cover their own
weight and the pressure -, whilst in front of all these teeth the whole play is
accumulated at the disposal of the tooth which falls (shown at j & j¹), and which
makes a joint with that in front which is fixed at the moment it crosses the
horizontal line; Fig. 1 represents a more practical arrangement than that which
has just been described. It is an arrangement of three teeth or wings only; as in
the arrangement above described it is the friction of the tooth upon the envelope or
the raising of its own weight and the difference of pressure which stop the
tooth on its crossing the horizontal line at the moment that it supports the pressure
of the tooth which gears with it, and which supports itself freely upon it having
double play at its disposal. To fix the tooth on its crossing the horizontal line I
give a certain excentricity to the shaft with regard to the envelope or cover in such
a manner that the friction only commences at the part indicated at A, Fig. 1;
Fig. 2 shows the mode of fixing by means of two fixed rings B, B, having set screws
which move in the groove upon the flange. This arrangement may also be applied
to wheels with two teeth or wings, as shown at Fig. 4, the excentricity being
arranged so as to have the greatest friction in the top quarter. It is equally
applicable to rotary machines, pumps, and ventilators.
cover,
Having now described my Invention for " "Improvements in Ventilators or
Blowers," and the manner in which the same is set forth, I wish it to be understood
that what I claim is the relative independence of the teeth or wings in rotary
machines, pumps, and ventilators, permitting the perfect and continuous contact of
these teeth or wings by means of their relative movability, which compensates for
the irregularity of form arrising from wear or any other cause, as herein described
and shown in the Drawings.
In witness whereof, I, the said Arthur Crespin, have hereunto set my hand
and seal, this Twenty-sixth day of July, in the year of our Lord One
thousand eight hundred and seventy-six.
Witness,
H. I. ALLISON,
7, Avenue Parmentier,
Paris.
A. CRESPIN. (L.S.)