US1196494A - Speedometer. - Google Patents

Description

G. S. TWFNY.,

SPEEDOWIETER.

APPLICATION men ocr. 24. 1914.

Mmmm Aug., 29, 119%?.

l ill ci GEORGE S. TIFFANY, OF SUMMIT, NEW JERSEY, ASSIGNOR T THE DEVICE TESTING COMPANY, A CORPCRATION OF CONNECTICUT.

SPEEDOMETER.

Specification of Letters Patent.

Patented Aue. 29, 1916.

Application led October 2t, 1914. Serial No. 868,364.

To IZ whom it may concern:

lie. it known that I, GEORGE S. TIFFANY, a citizen of the United States of America, and a resident of Summit, Union county, New Jersey, have invented certain new `and useful 'Improvements in Speedometers, of which the following is a specification. f

'l his invention relates to improvements in electrically operated mechanisms or apparatus, such as speedometers for instance, yand the object of the invention is to provide cer` tain improvements in combination with the speedometer or other apparatus whereby to simplify the operation thereof and to eliminate certain disturbing infiuences or factors with a view of rendering the speedometer or other apparatus dependable and certain in its functions and operations.

lith this and other objects in view, all

of which will be pointed out as this speciication proceeds, the invention is embodied in and comprises the elements arranged and combined with a speedometer as hereinafter set forth and as shown in the accompanying drawing which illustrates an electrically operated speedometer improved according to my invention and in which drawing- Figure 1 isa wiring diagram illustrating the invention. Fig. 2 is a detail view of the eonimutator. -Fig. 3 is a plan view of the speedometer. and Fig. 4 is a substantially central sectional view of the speedometer.

.fait

The speedometer as herein described and illustrated comprises an electromagnet wound to provide a rotating magnetic field having a centrally disposed non-rotatable armature between which and the electromagnetthere is mounted a movable indicating element in inductive relation to the magnet. Suitable means are provided for supplying current to the electromagnet.

Referring to the drawing the numeral indicates the armature of soft iron laminas suitably mounted within a casing 11 of non magnetic material. Surrounding the armature 10 there is provided an electromagnet comprising the core 1Q and the poles 13 between whiclry are wound the coils 14. The latter are connected serially to the segments 15 of a commutator 1G which is suitably secured' to a bracket 17 which may form a bearing for the shaft 18the speed of which is to be measured.

19, 19 are brushes mounted in a brush holder 20 which is secured so as to rotate with the shaft 18. The brushes are connected across the battery 21, or other source of electrical energy by the battery circuit QQ, QQ in which 23 represents a controlling switch. Current is supplied to the brushes 1*.) by way of sliding contacts Q4 in an obvious manner.

From this description it is apparent that during the rotation of the shaft 18 a rotating magnetic eld is produced between the armature and the eleetromagnet.

The speed indicator 25 of aluminum or similar material is mounted to rotate betweenthe armature and the eleetromagnet 12-14 so as to cut the magnetic lines of force between these two elements. For this purpose the indicator is provided with a skirt or cylinder QG which surrounds the armature as shown. The indicator is provided with a scale Q7 which is read with reference to a fixed mark QS on the cover of the casing 11. -The pivot 29 of the indicator has its bearings `in the cover and in the armature as shown.

30 is a hair spring which tends to keep the indicator at zero position and 31 represents stops for liniiting'the movement of the indicator.

The rotating magnetic field produced when the shaft 18 is rotated and the battery circuit is closed imparts a rotative tendency to the indicator in the direction of rotation of the magnetic field and in direct propor tion to the rotative speed of the shaft, such rotative tendency being opposed by the spring 30 in such a proportion with respect to the magnetic effect created by the electromagnet as to cause the indicator to re- .volve to an extent 1n direct proportion to the speed of the shaft 18, and hence when said indicator is properly calibrated, the exact speed of the-rotation of the shaft will be indicated in the graduations of the scale 97 with referenceto the mark 28. The stops 31 prevent the indicator from making more than one revolution as will be understood'.

From the foregoing it will be clear that the speed of the shaft 18 may be read directly by means of the scale 2.7 in the indieator because the movement of the latter is in direct proportion to the speed of the shaft. This condition.y however, exists only while the strength of the rotating ma etic field remains practically constant. qliiriation therein, which is due to variations in the voltage `of the current, influences the nuwcment of the indicator as is obvious and thc latter does not then correctly indicate the speed of the operating shaft 18. An inances caused by variations in the strengthv of the rotating magnetic field due to an increase or decrease in voltage in the circuit from that for which the apparatus is designed. To this end there is inserted in the battery circuit 22, 22 an electromagnet 32 having a pivoted armature 33 which is kept in contact with a contact 34 by means of a spring 35. AA resistance 36 is connected between the arn'iature 33 and the circuit 2Q. The spring and the eleetroxnagnet 3Q`are so proportioned that when the voltage in the circuit is normal or equal to that for which the apparatus is designed, the electromagnet is not strong enough to overcome the force of the spring. The contact of the armature at 3l remains closed. and the operating circuit is traced through the clcctromagnet 32, the armature 33, the contact 34 and through the wires 9:2 to the speedometer. At a higher voltage, the electromagnet 32 overcomes the resistance of the spring 35 and attracts .the armature 33 Which puts the resistance 36 in the circuit so that the voltage for the speedometer is not increased.

When the battery is the sole source of.

current sup ly it is preferably overcharged so that it will discharge current at a higher to charge the latter in which case the resistance will be put into or cut out of the circuit automatically and in response to variationsin the voltage, but will not neces- `sarily be in the circuit at the start of the operation of the speedometer.

41 represents diagrammatically a speed controller switch and i2 a reversel relay such as are usual and well known in the art for the proper operation of the generator.

Thus it will be seen, that whether thc circuit commences to operate at a too high voltage for the speedometer or at normal or required voltage which thereafter varies, the voltage for the speedometer is automatically regulated to that required for its proper operation.

From the foregoing it will bc seen that means have been provided whereby the operation of the speedometer is automatically regulated with respect to variations in voltage andv that the disturbing influence of the latter is eliminated.

While I have described the invention with reference to a specific form of speedometer and embodied the lprinciples of the invention in certain specific elements, I do not wish to he understood as limiting my invention to the embodiment illustrated and described, but claim all such modifications which properly come within the scope of the appended claim.

I claim The combination of a speed indicator, a shaft, electric means for operating said indicator kand controlled by the speed of said shaft, said electrioineans including a circuit, mechanism for compensating changes of voltage in said electric circuit and comprising an electromagnet and arn'iature'connected in said circuit and a resistance connected to the latter and the said armature.

Signed at New York, N. Y., this 23d day of Oct., 1914.

GEORGE S. TIFFAN Y.

K. G. LE Ann.

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