US2658328A - Automobile clock - Google Patents

Description

1953 R. G. RICHARDSON ET AL 2,658,328

AUTOMOBILE CLOCK Filed July 24, 1948 MIIIII' WW 4 40 a7 3 55 INVENTORS 34 RODNEY G. RICHARDSON JEAN F/NK ATTX Patented Nov. 10, 1953 2,658,328 AUTOMOBILE stock Rodney G. Richardson and Jean l inlh-Delavaii; Wis.; said Fink assignor to The George W. Borg Corporation, D'e'lavan, Wis., a corporation or Delaware; Rodney G. Richardson, J12, administrator of said Rodney G. Richardson, deceased Application July 24, 1948, Serial No. 40,515

5 Claims.

The present invention relates in general to automobile clocks, but more in particular to spring driven automobile clocks which have automatic electro-magnetically operated winding mechanisms; and the object or" the invention is a new and improved switch for controlling the circuit of the winding electro-mag'net in a clock of this character. I v

An automobile clock of the type with whichthe invention is concerned is disclosed: in the patent to Hobbs, No.2,165ll-9', granted February '7, I939. As shown in the drawing, however, the invention is applied toanimproved clock, disclosed in the pending application of Glenn, Serial No. 710,983, filed November 20, 1946, in which thewinding mechanism" is a complete unit in itself and is detachable from the clock movement and interchangeable with other winding mechanisms.

In the clocks referred to in the foregoing the circuit of the'winding electro=niagnet is controlled by a switch of the snap acting type in which the power for operating it is supplied by a spring which is tensioneol by the main spring while" driving theclock. Since the switch operating spring is tensioned just prior to rew'inding, the power which is required to tension it is supplied by the main spring at a time when the latter spring has lost a large part of. its own tension and has" little power remaining beyond what is required to drive the clock. It is necessary, therefore, to use a rather light switch operating spring, resulting in low contact pressure, or a stiiier main spring, which requires a more powerful electro-magnet. These expedients' do not give results" which are entirely satisfactory from an electrical standpoint, but they do make it possible to produce a clock which operates reliably in so far as rewinding is concerned.

The quality of such clocks as time lzee'pers'is a different matter, however, for the extra load which is imposed on the main spring toward the end of each running period has a considerable effect on the rate; The running period may be about two minutes, for example. During the greater part of this period the rate of the clock will be substantially constant but toward the end of the period, for about one half minute the're is a loss of power due to the eiitraload imposed on the main spring, the amplitude ofthe balance decreases, and if the clock has isochronal error, as most of them do, a change in rate occurs. The change varies but may be considerable.

It might be expected that since the change occurs periodically just prior to rewinding there would not be any net gain or loss, but such is not the case. There are various reasons for this which it will be unnecessary to explain in detail. One reason which may be mentioned is the change in the length" of the running period due to changes in the battery voltage. I I

In additionto its adverse effect on the time keeping quality of the clock the periodic change in rate which occurs makes it difiicult' to time the clock by means or standard timing apparatus.

- in the process of regulating clocks in the factory it is desirable to use timing apparatus such as is disclosed, for example; the patent" to Gibbs, No. 2,421,781, by means of which the rate of a clocl; can be determined in a very short period of time such as one half minute. It will be clear, however, that a clock which changes its rate for an interval of about one half minute every two minutes cannot be timed half a minute or even in a mu minute, but requires a timing interval which is long enough to cover a complete cycle of operation, that is, a timing interval of more than two minutes.- This greatly slows down the procease of regulating such clocks.

It may be stated here that a clock such as disclose d by Hobbs" is capable of rewinding s'ufiici'ently to give a" running period of between three and four minutes and that the running time is reduced to about two minutes by adjustment of theswitch in order to minimize the eiie'ct of switch operation on the time keeping quality of the clock; 1

A clock having a switch constructed in accordancewith' the invention is not subject to the objections which have been pointed out. The switch comprises" aperrna'nent magnet mounted onjthe' rotatable armature of the" winding electromagnet and an auxiliary armature mounted on the movable contact member of the switch. The permanent magnet moves in the arc of a circle while the rotatable armature is driving the clock under power supplied by the mainspring and during the latter: portion of the running period it approaches the" auxiliary armature, finally coming close enough to'operate it and close the switch. The auxiliary armature has a pivotal connection to the movable contact member and is provided with a fixed fulcrum sothat it operates as a lever in closing the switch. The movement of the auxiliary arma'ture'lduring this operation changes its position relative to the path of the permanent magnet so that it remains attracted and holds the switch closed diiring a substantial part of the movement of the rotatable armature during the ensuing winding operation.

During the latter part of each running period the increasing attraction between the permanent magnet and the auxiliary armature supplies an appreciable amount of power for driving the clock. Thus the operation of the switch not impose any additional load at all on the main spring but on the contrary the arrangement is such that the main spring is assisted in its driv ing function at the time when assistance is most needed.

The result of the foregoing is a substantial improvement in the accuracy of a clock of this type, which adds greatly to its usefulness as an automobile accessory. The improvement in ac curacy is largely due to the elimination of the rate change toward the close of each running period, which gives the further advantage that clocks equipped with the new switch may be timed on standard timing machines as fast as watches.

The foregoing and other advantageous features will be described more in detail in the following specification, reference being had to the accompanying drawing, in which Fig. 1 is a top or plan view of a clock winding mechanism having a switch constructed in accordance with the invention, said mechanism being shown in wound position and the switch being open;

Fig. 2 is a partial view of the same winding mechanism, shown in run down position and with the switch closed;

Fig. 3 shows the winding mechanism in elevation, providing a front view of the switch in open position; and

Fig. 4 is a perspective view of the permanent magnet and the bracket for mounting it on the armature of the winding electro-rnagnet.

Referring to the drawing, the various parts of the winding mechanism are mounted on a frame which includes the circular back plate Iii and the Tshaped armature bearing plate H. These plates are held together in spaced relation by the three pillars l2, l3, and M, as shown in Fig. 3.

The electro-magnet has a winding I5, a core l9, and two pole pieces l6 and H. The pole pieces may be stamped from sheet stock and are assembled on the core as shown in Fig. 1. The electro-magnet is mounted on the back plate Hi. For this purpose the pole pieces i6 and H are provided with integrally formed studs such as l8, Fig. 3, which extend through holes in the back plate and are staked or upset by riveting to hold the electro-magnet in place.

The armature 2|] is rotatably mounted on the bearing plate H by means or the shoulder stud 2| and the washer 22. The main spring is indicated at 23 and tends to rotate the armature in a clockwise direction. During such rotation the pawls 25 and 2B engage a ratchet wheel (not shown) which is part of the clock movement and the spring 23 thus furnishes power for driving the clock. The arrangement is shown in detail in the Hobbs patent and also in the application of Olson previously referred to.

The armature 20 is shown in wound position in Fig. 1. As it rotates slowly to drive the clock the spring 23 gradually loses its tension but before this has proceeded too far the switch to be described hereinafter is closed and the electro-magnet is energized. The armature is then quickly rotated in a counter-clockwise direction to its wound position. During this movement of the armature, the switch is opened to deenergize the electro-magnet and the main spring is retensioned, so that it can resume its function of supplying power to rotate the armature 20 and drive the clock. The clock movement includes the known means for maintaining power during the winding operation.

Proceeding now with a description of the switch, it includes a fixed contact member which is mounted on the back plate It by means of the rivet 3|. Insulators are provided as shown in Fig. 3 whereby the contact member is electrically insulated from the back plate.

The switch includes a movable contact member in the form of a curved contact spring 32 which is also mounted on the back plate it. For

=' this purpose the spring 32 has an integrally formed base 33 which rests on the back plate and is secured thereto by the binding post 34. This binding post extends through the back plate, the base 33 of the spring and the washer 35 and the end is upset by a riveting operation to hold the parts together. For additional security as regards the spring 32 the back plate ii] preferably has a projection 36 which extends into a hole in the base 33 of the spring and eliminates any chance of its rotating on the binding post 34.

For a substantial portion of its length the spring 32 is made stiff and inflexible by means of two flanges 3'! and 38 which give this portion of the spring a U-shaped cross section. Two cars such as 351 are formed integrally with these flanges and afford means for pivotally supporting the armature Ml. The reference numeral indicates a pivot pin which extends through the aforementioned ears and a projecting part of the armature which lies between them.

The contact member or spring 32 is tensioned so as to normally hold the switch in open position, as shown in Fig. 1. In this position the end of the armature 40 is in engagement with the flanges 37 and 33 of contact spring 32 and the extension 42 of the armature is in engagement with the fixed pin 43 on the back plate it. The pin 43 thus acts as a stop to determine the distance separating the switch contacts when the switch is open. The spring 32 should not be too stiff, but should have sufficient tension to positively open the switch and move the parts to the Fig. 1 position.

The reference character 44 indicates a. small permanent magnet which cooperates with the armature 40 to close the switch, as will be explained presently. The magnet is mounted on the armature 20 by means of the bracket it. This bracket may be secured to armature 253 by a rivet 4d and has arms 46 and 4"! which encircle the magnet and hold it securely. The magnet is preferably made of Alnico or similar alloy.

The spring 32 has two integrally formed extensions 50 and 5!. The extension 5% has a rounded part which projects slightly into the path of the permanent magnet and may be utilized to initiate the opening of the switch. The extension 5i is engaged by the armature 20 and may function to initiate closing of the switch if normal closing does not take place. The purpose of these extensions will be explained more in detail later on.

The reference character indicates another binding post which is riveted to the back plate like binding post 34, except that suitable insulators are provided to electrically insulate the binding post 55 from the back plate. The clip or terminal 56 is conductively connected to binding post 55 and is soldered to one end of the winding of the electro-magnet. The other end of the winding is soldered to the fixed contact member 30.

The operation of the switch will now be described more in detail. For this purpose it Will be assumed that a clock movement is assembled to the motor mechanism and that the clock, complete with case, is installed in an automobile. The binding post 5-5 is connected to the live pole of the battery, while the binding post 34 is connected to the frame at some convenient point and is thus comiected to the grounded pole of the battery.

As previously mentioned, the spring 23 drives the clock by rotating the armature 2B in a clockwise direction as seen in Fig. 1, the pawls 25 and 28 performing the driving function by engaging and rotating a ratchet wheel which is part of the clock movement. .Ihe motor mechanism is fully wound or substantially so in Fig. 1. The switch is open, that is, the contact spring 32 is separated from the contact member 33' and the electro-magnet is deenergized.

During the rotation of the armature 25 as described in the preceding paragraph the permanent magnet it moves in the arc of a circle and the poles of the magnet gradually approach the armature 58'. At the beginning of this movement the magnet and armature are so far apart that the attraction between them is very small but u the attraction increases rapidly as the distance diminishes until it produces an appreciable force tending to aid the spring 23 in rotating the ar mature 29. This force increases according to the inverse square law and reaches a maximum just prior to closure of the switch.

The armature asis operatively attracted by the permanent magnet it when the latter reaches the position in which it is shown in- Fig. 2, or approximately that position.

The pull which the magnet exerts on the armature operates the armature as a lever, having a fulcrum on the pin 63, and the contact spring 32 is operated by means of the pivotal connection t! to close the switch, the parts assuming the position in which they are shown in Fig. 2. The pull increases rapidly during movement of the armature, resulting. in quick and positive closure of the switch and a strong contact pressure after the switch is closed. In the switch shown herein the contact pressure is more than ten times the contact pressure in the I-Iobbs switch.

When the switch is closed as described in the foregoing,v the electro-magnet is energized and the armature is quickly rotated in a counterclockwise direction to its Fig. 1 position. This movement of the armature 2B is accompanied by the return movement of the permanent magnet 6 2, but the armature 48 is now in a position relative to the path of the magnet which enables it to hold the switch closed during a substantial part of such return movement. The electromagnet thus has a chance to become fully energized, whereby the armature 20 is positively rotated to retension the spring 23. As the armature 20 approaches its Fig. 1 position the armature GE) is released by the permanent magnet and the switch is opened quickly by the restoration of contact spring 32, which also restores the armature 4B. The electro-magnet then ole-energizes, the pawls and 26 take a fresh hold on the ratchet wheel and the drive is resumed under power supplied by the retensioned main spring 23.

The extension 56 is adjustable along the path traveled by the permanent magnet and may have either of two positions, depending on the operation desired. In one position the rounded end of the extension is far enough to the right along the path of the permanent magnet so that the armature 4% is released and the contact spring 32 is restored before the magnet reaches the extension. With this adjustment of the extension it is never engaged by the permanent magnet in the normal operation of the motor mechanism and functions to start the opening of the switch only in the event that the armature 40 should fail to be released.

The other adjustment of the extension 50 locates the rounded end farther to the left, where it is engaged by the permanent magnet before the armature 56 is released. This is the position in which the extension is shown in the drawing. With this adjustment the extension 53 is engaged by the permanent magnet each time the electromagnet is energized and functions to cause the switch to open every time at a definite point in the rewinding movement of armature 26, thereby producing uniform winding or retens-ioni-ng of the spring 23. It is thought that the operation will be readily understood, but it may be pointed out that by the time the permanent magnet engages the extension 59 during a winding operation its attraction for the armature 46 has decreased substantially, although the armature is still at' tracted with suihcient force to overcome the tension in spring 32 and hold the switch closed. With this condition obtaining, the sharp impulse produced by the impact of the magnet on the end of the extension is all that is required to start the release of the armature 45, whereupon the switch is opened and the armature is restored by the contact spring 32.

The extent to which the electro-magnet is able to rotate the armature 2E3 depends on a number of factors, one of which is the voltage of thebattery. The winding mechanismv is designed to operate on 6 voltsbut has a certain factor of safety, which enables the clock to operate on a lower voltage, whereby no trouble is encountered due to the voltage variations which ordinarily occur in the operation of an automobile. Under extremely unfavorable conditions, however, such as occur during. cold weather starting, the battery volt-- age may fall so low as. to substantially limit the extent to which the armature can be rotated by the electro-magnet, which would prevent opening of the switch. were it not for the provision of the extension 5E9. When. adjusted as described in the immediately preceding paragraph the extension 58 is engaged by the permanent magnet early enough during the winding operation to insure opening of the switch under any battery condition which will enable the car to be started.

The extension 5! is a stop which is engaged by the armature 2G in the event that the switch does not close when it should, resulting in continued rotation of armature 2% in a clockwise direction until it engages the stop 5 I. When this occurs the mainspring 23 builds up pressure on contact spring 32 which tends to assist the armature so in closing the switch and usually will be suilicient to close it before the main spring loses enough tension to stop the clock. It will be understood, of course, that the stop 5| functions in this way only when the switch is badly out of adjustment or repair, and is provided so that the clock may continue to run under such condition until the necessary service can be obtained.

The principal advantages in the new switch are due to the total elimination of the switch 1 operating load on the main spring and substitution for this load of a force in the other direction which assists the main spring. This feature results in an improvement in the time keeping quality of the clock and makes it possible for standard timing apparatus to be used in regulating the clocks in the factory. It is also possible to increase the running period substantially, which reduces the winding frequency and thus increases the life or the switch.

Another advantage is the greatly increased contact pressure which is obtained, which avoids trouble due to dirt or dust between the contacts and insures positive closure of the electro-magnet circuit. This not only makes for reliable operation of the electro-magnet, but eliminates arcing or burning of the contacts upon closure of the switch.

The invention having been described that which is believed to be new and for which the protection of Letters Patent is desired will be pointed out in the appended claims.

I claim:

1. In a clock, a reciprocating driving member, a main spring for moving said member in one direction to drive the clock, an electro-magnet for moving said member in the opposite direction to tension said main spring, a switch for controlling the circuit of said electro-magnet, said switch including a movable contact memher, a permanent magnet mounted on said driving member, an armature pivotally mounted on said contact member and adapted to be attracted by said permanent magnet in one position of said driving member, and a fulcrum cooperating with said armature to enable the latter to operate as a lever to close said switch.

2. In a clock, a rotatable driving member, a main spring for rotating said member in one di rection to drive the clock, an electro-magnet for rotating said member in the opposite direction to tension said main spring, a switch for controlling the circuit of said electro-magnet, said switch including a switch contact supported on a spring tensioned to hold the switch open, a lever mechanism for closing said switch by bending said spring, an armature forming part of said mechanism, and a permanent magnet mounted on said driving member for operating said lever mechanism by attracting said armature.

3. In a clock, a rotatable driving member, a main spring for rotating said member in one direction to drive the clock, an electro-magnet for rotating said member in the opposite direction to tension said main sprin a switch for controlling the circuit of said electro-magnet, said switch including a movable contact member, a permanent magnet mounted on said drivin member, an armature operated by attraction of said permanent magnet to close said switch, and thereby terminate the driving movement of said driving member, and a pivotal connection between the contact member and armature permitting the armature to change its position relative to the path of the permanent magnet so as to be held in attracted position by the permanent magnet during a part of the ensuing spring tensioning movement of said driving member.

4. In a clock, a rotatable member having a driving movement and a winding movement, a main spring for rotating said member in its driving movement, an electro-magnet for rotating said member in its winding movement, a switch for controlling the circuit of said electro-magnet, a permanent magnet mounted on said member, an armature operated by said permanent magnet during said driving movement to close said switch, and supporting means for said armature arranged to bring about a movement of said armature incidental to the said closing operation which enables said permanent magnet to hold the armature in operated position during a part of said winding movement.

5. In a clock, a rotatable member having a driving movement and a winding movement, a main spring for rotating said member in its driving movement, an electro-magnet for rotating said member in its winding movement, a switch for controlling the circuit of said electro-magnet, a permanent magnet rotating with said member, an armature operatively attracted by said permanent magnet during said driving movement to close said switch, and means operatively engaged by said member to start the movement of said armature in case its operation by said permanent magnet is delayed.

RODNEY G. RICHARDSON. J EAN FINK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,770,677 Stern July 15, 1930 1,970,412 Bates Aug. 14, 1934 2,146,119 Hobbs Feb. '7, 1939 2,459,930 Fink Jan. 25, 1949 2,465,582 Fink Mar. 29, 1949

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