An Improved Pneumatic Velocimeter or Speed-indicator.
Year: 1895

page_text: Date of Application (in United Kingdom), 20th Mar., 1895
Complete Specification Left, 20th M.r., 1895-Accepted, 20th Apr., 1895
An Improved Pneumatic Velocimeter or Speed-indicator.
I, LOUIS PIERRE HENRY DE PLACE, of 32, Avenue Rapp, Paris, in the
Republic of France, Captain in the French Army, do hereby declare the nature
of this invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement:-
The subject of this invention is a pneumatic velocimeter characterised by the
employment of a paddle-wheel or fan, and operated by the machine, whereof the
speed is to be ascertained (whether such machine be stationary or adapted for
locomotion); the operation of the paddle-wheel or fan having the effect of setting
in motion a turbine or its equivalent, mounted upon a shaft or spindle of its own,―
i.e., separate from that of the paddle-wheel or fan-the continuous rotary motion
of the turbine being resisted by a spring or weight, or by gravity or centrifugal
force.
In the accompanying drawings, I have shown, by way of example, the application
of my improved velocimeter to a bicycle.
Fig. 1 represents a side elevation of so much of a "safety" bicycle as is
necessary to illustrate the mode of applying my invention.
Fig. 2 is a detached view in section, drawn to a larger scale, of the improved
velocimeter; Fig. 3 being a horizontal section through the paddle-wheel or fan
and turbine.
In a speed-indicator constructed according to my improved method, and applied
to a cycle, the paddle-wheel or fan a is mounted upon a shaft or spindle V, which
receives motion from the machine (the speed of which it is desired to ascertain),
through the medium of a roller R in tangential or frictional contact with the tyre W
of one of the cycle wheels. Owing to the rotation of the cycle wheel, the said
roller R is caused to turn about its axis, and through the medium of the spindle V
transmits rotary motion to the paddle-wheel or fan a.
In the drawing, a single spindle V is shown connecting the roller R with the
paddle-wheel a ; but the part V₁ of the spindle may, if desired, be made separate
from the part V, and the motion from the one part to the other be transmitted by
any suitable means.
In the plane of the paddle-wheel a, and surrounding the same, are disposed the
blades t of a turbine or similar wheel, these blades being by preference convex,
and turning or tending to turn in the same direction as those of the paddle-
wheel a.
This transmission of motion takes place with a speed proportionate to the afflux
of wind, which is in its turn proportionate to the speed of the paddle-wheel a, which
speed again stands in a predetermined relation to the speed of the cycle or machine
in motion

page_text: The turbine t would continue to turn indefinitely were it not provided upon its
spindle or shaft T with a spiral spring r, one end of which is attached to the said
shaft or spindle T, while the other end is connected with a finger h secured to the
casing B of the mechanism. The shaft or spindle T of the turbine carries at its
outer extremity an index-hand m adapted to move in front of a graduated
dial C.
It will be readily understood that this hand m will turn with the turbine t, and
that such rotation will increase in amplitude in proportion as the speed to be
measured becomes more considerable, the spring r being extended or compressed,
and its power being so calculated that the index-hand m may complete an entire
revolution upon the dial C in travelling from zero to the maximum speed which
the speed-indicator or velocimeter is capable of recording.
As a modification of the mechanism described, the paddle-wheel or fan a may be
dispensed with, and, instead of the friction-roller R which actuates the apparatus,
I may employ a fan, also operated by frictional contact with the tyre of the cycle.
The spindle V in this arrangement would be in the form of a tube. In operation,
the fan takes in a supply of air at its periphery, and delivers it at the centre into
the tube, which conveys or leads it to the case enclosing the turbine, thereby
setting the latter in motion. The turbine is controlled by a spring.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I claim :-
1. The improved velocimeter or speed-indicator arranged or operating substan-
tially as herein described with reference to the accompanying drawings.
2. In a velocimeter or speed-indicator of the character herein referred to, the
employment of a paddle-wheel or fan driven by the machine (whereof the
speed is to be ascertained) in conjunction with a turbine or its equivalent,
substantially as herein described; pressure due to the current of air generated
by the revolving paddle-wheel or fan causing the turbine-wheel to turn
about its axis against the resistance of a spring or the like, the extent of such
turning movement being indicated by a finger carried by the said turbine.
3. For operating the paddle-wheel or fan in apparatus of the character herein
referred to, the employment of a roller or its equivalent, mounted upon the fan-
spindle and maintained in frictional contact with the wheel of the machine
whereof the speed is to be ascertained, substantially as herein described.
Dated the 20th day of March 1895.