US2623926A - Vibrator testing apparatus - Google Patents

Description

Dec. 30, 1952 H. v. ELLIOTT ETAL 2,623,926

VIBRATOR TESTING APPARATUS Original Filed May 15, 1948 INVENTORS HAROLD V. ELLIOTT BROOKS H. SHORT THEIR ATTORNEYS Patented Dec. 30, 1952 UNITED VIBRATOR TESTING APPARATUS Harold V. Elliott and Brooks H. Short, Anderson, Ind., assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Original application May 15, 1948, Serial No.

1949, Serial No. 109,198

2 Claims.

This invention relates to apparatus for converting direct current from low voltage to higher voltage and more particularly to the vibrator which distributes current in succession to the primary windings of a transformer.

An object of this invention is to provide apparatus which will give a visual indication of the functioning of the vibrator to determine whether its contacts have been properly adjusted to obtain the required contact separation.

A vibrator which is adapted to be tested by the present apparatus is described and claimed in copending application, Serial No. 27,237, filed May 15, 1948, of which this application is a division, now Patent No. 2,541,223 issued February 13, 1951.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is an enlarged scale longitudinal sectional view of a vibrator which is adapted to be tested by the present apparatus.

Fig. 2 is a sectional view on line 22 of Fig. 1.

Fig. 3 is a reduced scale view of the tool which is used in adjusting the vibrator contacts.

Fig. 4 is a wiring diagram showing the connections of the vibrator with a current source and primary windings of a transformer.

Fig. 5 is a wiring diagram of the apparatus for determining whether the contacts have been properly adjusted.

Referring to Figs; 1 and 2 the vibrator comprises a frame 23 which provides a magnetic circuit" including a core 2i and pole pieces 22. The core 2| extends through a spool which comprises parts 23 and 24 of molded insulating material upon which are wound a tape layer 250., a coil 25 of wire and a tape layer 251). An insulating' spacer 25 and the assembly of spool and coil are placed upon the core 2| while the pole pieces 22 are spread apart. After making this assembly the parts 22 are bent into parallelism as shown in Fig. 2. One end of the coil 25 marked 21 in Fig. 1 is attached to the frame 20 and the other end is connected to a lead wire 28. The corners of core 2| are deformed to retain the spool.

Screws 3|! secure to the frame 20 a stack of parts comprising an insulator 3|, metal contact springs 321 and 331 in the same plane carrying respectively contacts 341 and 351 (Figs, 4 and 5),

Divided and this application July 18,

metal contact spring supports in the same plane, an insulator 3|, a metal spacer plate 38, a terminal plate 39, a reed 40, a second terminal plate 39, a second spacer plate 38, a second insulator 3 I, metal contact spring supports 35 in the same plane, metal contact springs 321 and 337 in the same plane and supporting, respectively, contacts 341' and 351 (Figs. 4 and 5), an insulator 3 a metal plate 4 I. All parts of said stack parts are insulated from the screws 3!] by nonconducting sleeves 42 except the plate 4|. Lock washers confined between the heads of the screws 3!] and the plate 4| resist accidental loosening of the screws. The four insulators 3|, the two spacers 38, the plate 4|, the two terminals 39 and the reed each have two holes receiving the bushings 42. The contact springs and the contact spring supports each have one hole for receiving a bushing. The grain of the metal of the reed is in the direction of the longer dimension of the reed.

The contacts 34Z, 35Z, 347, 351 are engageable respectively with movable contacts 542, Z, 541", 551 each having a spherical face and Welded to a rivet 58. Rivets carrying contacts 541 and 551 are attached to resilient contact supports 511; and the rivets carrying contacts 541 and 551 are attached to resilient contact supports 5T1. Supports 5' and 511" are attached by rivets 58 to the reed 43. An armature 50 is attached to the reed 40 by rivets 6| passing through the armature, the reed and a plate 52 against which the rivets are upset.

A wire l0 connects frame 20 with terminal plates 39 and reed 40 and plates 39 are connected by wire H with terminal 12 (Fig. 4). Wire 23 (Fig. 4) is connected with blade 331 which carries contact 351" and this blade is connected by wire 13 with a terminal 14. The blade 321" which carries contact 341 is connected by wire 15 with terminal 16. The blade 321 which carries contact 342 is connected by wire T1 with a terminal 78. The blade 331 which carries contact 351 is connected by wire 13 with a terminal 80.

The vibrator is connected as shown in Fig. 4 with the current source and primary windings of a transformer. Terminal 72 is connected by wire 93 and switch 9| with a storage battery 32 having one terminal grounded. The terminals l4, l5, l8 and are connected respectively with transformer primary sections 94, 95, 98 and H33 which are grounded at NH. The transformer secondary I02 is connected with a rectifier, the output terminal of which is connected with the apparatus,

such as a high frequency ignition s stem. requiring for its operation relatively h h voltage direct current. Satisfactory operation of the vibrator is obtained provided the contact closing periods of all of the vibrator contacts are such that ener izaticn of the four sections of the primary of the transformer are equalized. In order to determ ne whether such equalization exists the vibrator is tested by the apparatus shown in Fig. and its relatively fixed contacts are adjusted during the test in order to obtain equalization.

The test apparatus comprises a lever H8 which operates a shaft III carrying switch arms I I2, H3, H4, H5, H6 and III which are connected respectively with vibrator side contacts 841, 851, the vibrator coil 25, contacts 35r and 341' and ground. The other end of coil is grounded and the reed supported contacts are grounded. Switch arm H2 is engageable with contacts I2I, I22, I23, I24, arm II3 with contacts I8I, I32, I33, I34, arm II4 with contacts I4I, I42, I43, I44, arm II5 with contacts I5I, I52, I53 and I54, arm II6 with contacts I6I, I82, I88 and I64 and arm II! with contacts I'II, I'I2, I13 and III. Contacts I2I, I24, I32 and I83 are connected by wire I80 with transformer primary section I8I. Contact I34 is connected by wire I82 with transformer primary section I83. Wire I84 connects contacts MI, I42, I43, I44, I53, I54, I5I, I62 with transformer primary section I85. Wire I86 connects contact I84 with transformer primary section I8'I. The primary sections are connected with a battery I88 which is grounded. The transformer secondary wiring I99 is connected as shown with a buifer condenser ISI, rectifier tubes I82 and I93, resistances I58, I55 and voltage doubling condensers I98 and I9! connected respectively with rectifier output terminals I98 and I99, the former being grounded and the latter being connected with loading resistances 200 and 2III. A cathode ray oscilloscope 2I0 is connected between wires I88 and I84 in such a manner as to detect the behavior of the primary sections I8I and I85 and will show on a screen the traces of wave forms in these primary sections. The traces A indicate the behavior of one of the sections and the traces B the other. C is the base line on the screen. If the slanting portions or are equal in length to the slantin portions 19, this is an indication that the energization of the transformer primary section are equal, because the slant portions represent the functioning of the buffer condenser I9I. If two primary sections I8I and I85 are equally energized the buffer condenser will be equally discharged at the time the opposite pairs of contacts are closed.

For convenient reference in the description which follows the four pairs of cooperating vibrator contacts are marked I, II, III, IV. To begin the test the switch handle I I8 is moved from an oil-position into the first position shown in Fig. 5 thereby connecting contact pairs I and III respectively with primary sections I85 and I8I. If the wave forms on the oscilloscope screen are not equal, an adjustment of contacts 341 or 341' is made by bending the contact spring supporting plates 38 against which the contact supporting spring are biased. It will be observed that each plate 35 has a relatively narrow neck 3611, the bending of which will displace the head 36h of the plate 36 so as to change the normal contact gap. The bending of the neck 381i is effected by the T-shaped tool 220 shown in Fig. 3

which includes a handle integral with a shank 22I having a notch 222 wide enough to easily receive the neck 3612. By turning the handle the plate 36 can be easily bent in order to change the location of the fixed contact of a pair relative to the movable contact. The spacing of contact pairs I and III is adjusted by means of the tool until the wave form shows equal lengths of slants a and b as shown in Fig. 5. In the second operative position of the switch handle IIIJ, contacts III are dropped out and contacts I and IV are connected respectively with the primary sections I and I 8| The side contact 35Z is adjusted so that contacts IV are balanced with contact I. Contacts III and IV are now balanced with contacts I and can be used for duplex operation. The third operating position of the switch handle III'I drops contacts I, retains contacts IV connected with primary section IBI and connects contact II with primary section I85. Contacts II are balanced with contacts IV by adjusting the supports 36 which controls the position of contact 351'. All four sets of contacts are now balanced and the vibrator is presumably properly adjusted. In the fourth position of the switch all four sets of contacts are connected respectively with the transformer primary sections for full load operation and both resistances 288 and 28I are connected between the rectifier terminals I99 and I98. If the wave forms shown on the oscilloscope screen compares favorably with the wave forms obtained in the other three positions of the switch, the adjustment of the vibrator is satisfactory. If the wave forms obtained in the fourth position of the switch shows inequality, the test is repeated and further contact adjustments are made. Generally one repetition of the test is all that is required to perfeet the adjustment of the contacts.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follows.

What is claimed is as follows:

1. Apparatus for testing a vibrator having a reed fixed at one end, an armature supported by the other end of the reed, an electromagnet having a core offest from the armature and a coil surrounding the core, and first, second, third and fourth pairs of contacts, each pair including a reed-supported contact and a fixed contact normally separated from the reed-supported contact, the fixed contacts of the first and second pairs being at same side of the reed as the magnet core and the fixed contacts of the third and fourth pairs being on the opposite side of the reed, a transformer having its primary winding provided by four primary coils and having a secondary winding, a buffer condenser and a rectifier connected with the secondary winding, a loading resistance connected with the rectifier, a current source having one terminal connected with one end of each of the primary coils and the other terminal connected with the reed and with one end of the magnet coil, a cathode ray oscilloscope connected with the other end each of a certain two of the primary coils, switches having movable contacts respectively connected with the fixed contacts of the four pairs of vibrator contacts and a movable contact connected with that end of the magnet coil remote from the end connected with the current source, a manually operable member for moving the movable contacts simultaneously into different positions, circuits established by one of the movable contacts in each of its positions for completing a circuit between the magnet coil and one of said two primary coils whereby the magnet coil is energized to cause the reed to swing in the direction of the fixed contacts of the first and second pairs of vibrator contacts, circuits established by two of the other movable switch contacts in the first position of the member for connecting the fixed contacts of the first and third pairs of vibrator contacts respectively with those ends of said one of, and of the other one of said two primary coils remote from the ends connected with the current source, the closing of the first pair of vibrator contacts short-circuiting the magnet coil so that the reed swings away from the magnet core and effects opening of the short circuit and engagement of the third pair of reed contacts, circuits established by another two of the movable switch contacts in the second position of the member for connecting the fixed contacts of the first and fourth pairs of vibrator contacts respectively with those ends of said one of, and of the other one of said two primary coils remote from the ends connected with the current source, the closing of the first pair of vibrator short-circuiting the magnet coil so that the reed swings away from the magnet core and effects opening of the short circuit and engagement of the fourth pair of reed contacts, and circuits established by another two of the movable switch contacts in the third position of the member for connecting the fixed contacts of the second and fourth pairs of vibrator contacts respectively with those ends of said one of, and of the other one of said two primary coils remote from the ends connected with the current source,

the closing of the second pair of vibrator contacts short-circuiting the magnet coil so that the reed swings away from the magnet core and effects opening of the shortcircuit and engagement of the fourth pair of vibrator contacts.

2. Apparatus according to claim 1 in which, in the fourth position of the manually operable member, circuits are established by said four switch movable contacts which are respectively connected with fixed contacts of the four pairs of vibrator contacts for respectively connecting said fixed vibrator contacts with ends of the four primary coils remote from those ends connected with the current source and which, in the fourth position of the manually operable member, there is another switch actuated by movement of the member for connecting another loading resistance with the rectifier output terminals.

HAROLD V. ELLIOTT. BROOKS H. SHORT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,154,379 Estes Apr. 11, 1939 2,212,634 Buckingham Aug. 27, 1940 2,470,049 Nulsen May 10, 1949 OTHER REFERENCES Radio-Craft for April 1948, page 56.

The Radio Amateurs Handbook, 1945 edition, published by the American Radio Relay League; pages 185 and 186.

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