US2845804A - Servomechanism - Google Patents

Description

1958 D. R. LAMBERT 2,845,801

SERVOMECHANISM Filed March 16, 1956 United States Patent 2,845,804 SERVOMECHANISM Donald Rudolf Lambert, Carshalton, England, assignor to Powers-Samas Accounting Machines Limited, London, England, a British company Application March 16, 1956, Serial No. 572,147 Claims priority, application Great Britain May 4, 1955 1 Claim. (Cl. 74110) This invention relates to a servomechanism to control a relatively powerful mechanical movement by the use of a small stationary electro-magnet which, due to its low power supply, cannot of itself be employed to do the work.

According to the present invention there is provided a servomechanism comprising a reciprocable driving member, a motion-transmitter pivoted on the driving member for movement therewith and resiliently urged to an inactive position thereof, and an electro-magnet having an armature operable on energization of the electro-magnet to elfect pivoting of the motion-transmitter to the active position thereof thereby to position the motion-transmitter to transmit motion imparted thereto by the driving member.

In order that the invention may be clearly understood one embodiment thereof will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which:

Figure l is an elevation, partly in section, of servomechanism according to the invention, and

Figures 2 and 3 are views similar to Figure 1 but with the parts shown in different positions thereof.

Referring to the drawings a driving member 1 is supported for reciprocation, as indicated by the doubleheaded arrow, by any suitable means not shown. A motion-transmitter formed by a rocking bar 2 is pivoted at 3 to the driving member for movement therewith and a spring 4 is arranged resiliently to urge the motiontransmitter to the inactive position thereof illustrated in Figs. 1 and 3.

As illustrated in Fig. 1 the driving member is in the starting position thereof, and, when in this position, it engages a spring 5 which co-operates with an armature 6 pivoted at 7 to a small stationary electro-magnet 8 and presses the armature into the active position thereof at which the upper overturned end 9 of the armature is located in a notch 10 formed in the under side of the motion-transmitter 2. The electro-magnet 8 is included in an electric circuit 11 and is controlled by a switch 12 which may be manually operated or which can be mechanically or electrically operated as desired.

The motion-transmitter 2 is arranged to transmit motion imparted thereto by the driving member 1 to a bar 13 mounted for lengthwise sliding movement in guides 14, 15. The bar 13, on lengthwise movement thereof, may be arranged to operate any desired mechanism, as for example a multiple switch, a tripping or a setting mechanism' As can be seen from the drawings the bar 13 is provided with a notch 16 to be engaged by the nose 17 of the motion-transmitter 2 when this part is in the active position as shown in Fig. 2.

Fig. 2 illustrates the fully forward position of the driving member 1 with the motion-transmitter 2 in the active position thereof and illustrates the manner in which the motion transmitted to the motion-transmitter is imparted to the bar 13 to effect lengthwise movement thereof. From Fig. 2 it will be noted that the switch 12 is in the close Position thereof so that the armature 6 is re ed n i s act p s i n bythe electrom t 8 and the switch 12 is closed before commencement of the fcrwardmq m nt, that i mo emen t h left as viewed i he ra ings, f hedriving mem e n e the armature 6 is retained in its active position, as the d iv ng m be 1 moves o the left, as. vi wed n the drawings, the motion-transmitter 2 rides over the overturned portion 9 of the armature being thereby turned counter-clockwise about its pivot 3 against the action of spring 4. The underside of the motion-transmitter 2 rests against the top of the overturned portion 9 and during the forward movement of the driving member 1, the nose 17 engages in the notch 16 so that the continued forward movement of the driving member 1 and motion tranlsmitter 2 causes the slide 13 to be moved to the left, as viewed in the drawings. The slide 13 can be restored by any suitable means, not shown, as for example by a spring or by a positively operated restoring member. On return movement of the driving member 1 to the starting position thereof, the motiontransmitter again rides over the overturned portion 9 until the portion 9 of the armature enters the notch 10 when the spring 4 will restore the motion-transmitter 2 to the inactive position thereof.

In the event that, when the driving member commences its forward movement, the switch 12 remains open, as shown in Fig. 3, so that the electromagnet is not energized, the spring 4 is sufficiently strong to ensure that the armature 6 is moved counter-clockwise about its pivot 7 by the forward movement of the motiontransmitter 2 together with the driving member. During such forward movement, the spring 4 urges the motion-transmitter 2 into engagement with an abument, illustrated as a pin 18, extending laterally from the driving member. Thus, when the ele'ctro-magnet 8 is not energized, the motion-transmitter 2 remains in the inactive position thereof, as illustrated in Fig. 3, and the nose 17 of the motion-transmitter is retained in a position at which it is not engaged in the notch 16 but passes over the top of the slide 13 which, accordingly, is not moved lengthwise during this operation of the driving member 1. From Fig. 3 it will be noted that, during the forward movement of the driving member 1, the spring 5 is disengaged by the driving member, but on the return movement of the driving member the spring 5 is again engaged thereby so that the driving member 1 restores the armature 6 to the active position thereof illustrated in Fig. 1, in which the overturned end of the armature is again located in the notch 10.

In the foregoing description there has been described the provision of only one motion-transmitter on the driving member 1, but it is to be understood that a plurality of motion-transmitters can be supported by the driving member 1, each for control by an electro-magnet 8 to operate a slide 13 appropriated thereto. Thus, by selective operation of the switches 12, the slides 13 will be appropriately operated and by such a multiple relay a plurality of mechanisms can be selectively controlled. The servomechanism herein described is found to be particularly suitable for use in record controlled statistical machines in which control of relatively powerful mechanical movements is to be effected by an electrical signal the strength of which is, of itself, sufiicient only to effect energization of a small stationary electro-magnet.

I claim:

A servomechanism comprising a reciprocable driving member, a motion-transmitter pivoted on the driving member for movement therewith, a spring urging the motion transmitter about its pivot to an inactive posi- 3 tion thereof in which it is arrested by an abutment carried by the driving member, and an electro-magnet the armature of which is adapted on energization of the electro-magnet to effect rotation of the motion-transmitter about its pivot to the active position thereof, characterized in that the armature is pivoted to the electro-magnet and in the starting portion of the driving member is retained in active relation with the electromagnet by a second spring co-operating with the armature and engaged by the driving member to locate an end portion of the armature in a notch formed in the motiontransmitter, the arrangement being such that the armature is retained in its active position and effects rotation of the motion-transmitter if the electro-magnet References Cited in the file of this patent UNITED STATES PATENTS 2,225,252 Auld et a1. Dec. 17, 1940

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