US2909069A

US2909069A - Mechanical power amplifiers

Info

Publication number: US2909069A
Application number: US476422A
Authority: US
Inventors: Duncan N Macdonald
Original assignee: Consolidated Electrodynamics Corp
Current assignee: Consolidated Electrodynamics Corp
Priority date: 1954-12-20
Filing date: 1954-12-20
Publication date: 1959-10-20
Anticipated expiration: 1976-10-20

Description

' Oct. 20', 1959 D. N. macmmm 2,909,069

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ATTORNEYS Oct. 20, 1959 D. N. M DONALD 2,909,069 uECHAnIcAL'PowER AMPLIFIERS Filed Dec. 20, 1954 2 Sheets-She et 2 me. a

- CLOSED LOOP - ssm/o 63 55 srsrsu INVENTOR. DUNCAN M MACDONALD BY mid; 711-14.

1 A TTORNEVS United States Patent 2,909,069 I MECHANICAL POWER AMPLIFIERS Duncan N. MacDonald, Arcadia, Califl, assignor, by mesne assignments, to Consolidated Electrodynamics Corporation, Pasadena, Calif., a corporation of California Application December 20, 1954, Serial No. 476,422 3 Claims. (Cl. 74-25) This invention relates to mechanical power amplifiers and more particularly to apparatus for converting a relatively small amount of electrical energy into a strong mechanical force capable of moving heavy loads in a very short time.

In various types of installations, for example, computer systems in which magnetic tape must be accelerated and decelerated at high rates, and hydraulic servo-systems in which high speed sliding valves must be operated, relatively large mechanical loads must be moved in very short times. Quite often the movement of the heavy loads must be in response to electrical signals. Thus, there is presented the problem of moving heavy loads in a very short time in response to an electrical signal. A solenoid is a well known device which converts electrical energy into mechanical movement. However, in order for a solenoid to move a heavy load directly, the solenoid requires actuating coils with many turns of wire and heavy moving parts. These requirements are detrimental to quick operation due to the electrical and mechanical inertia of the system.

This invention solves the problem of moving heavy loads electromagnetically in a very short time by using a high speed conventional clapper-type solenoid in conjunction with a motor driven capstan or power drum around which is disposed an actuating band adapted to be connected to a relatively heavy load. The solenoid has a light weight plunger or clapper which reacts almost instantaneously in response to an electrical signal to exert a slight force on the actuating band and drive the band into driven relationship with the rotating power drum. Since the power drum is rotated at a relatively high speed, practically no inertia delay is present and the large amount of power available in the power drum is applied almost instantaneously to the actuating band.

In a presently preferred embodiment of the invention,

the actuating band is wrapped loosely around the rotatable power drum. One end of the band is arranged to be connected to the load and the other end of the band is connected to move in response to the movement of the plunger of the solenoid. Thus, when the solenoid is actuated, the light-weight plunger moves swiftly to take the slack out of the actuating band and cause it to be drawn tightly around the rotating power drum. In this manner a large force is applied almost instantaneously to the actuating band and the load in response to the slight move ment of the light-weight plunger in the solenoid. With this arrangement of the length of the power stroke is approximately equal to the distance through which the plunger moves. As used in this invention, the term actuated as applied to a solenoid includes either energizing or de-energizing the solenoid.

In another form of the invention where relatively long power strokes may be obtained, the plunger of the solenoid is arranged to move a roller positioned adjacent the power drum so that the actuating band is forced against the power drum. Thus, the length of the power stroke is independent of the length of travel of the plunger.

e 2,909,069 Patented Oct 20, 1959 In another arrangement for obtaining relatively long strokes, the actuating band is disposed around arotatable power drum and an idling drum. The plunger of the solenoid is arranged to force the band into driven relationship with the power drum by either removing the slack from the band or pressing the band againstthe power drum. j

For obtaining movement of the load in either one of two directions, two rotatable power drums are arranged to drive a common band in opposite directions, and a separate solenoid is used with the band to be moved in either one of two directions in response to an electrical signal. This provides a fast action servo-drive which may be connected in a closed servo-loop system for driving recorders, plotters, computer systems and the like.

These and other aspects of the invention will be more completely understood from the following detailed description taken in conjunction with the accompanying drawings in which: a

Fig. 1 is a schematic front elevation of the presently preferred embodiment of the invention;

Fig. 2 is a side elevation taken on line 22 of Fig. 1;

Fig. 3 is a schematic front elevation of an alternate embodiment of the invention; g

Fig. 4 is a side elevation taken on line 44 of Fig. 3;

Fig. 5 is a schematic elevation of yet another embodiment of the invention; and i Fig. 6 is a schematic illustration of how the invention may be employed to drive an actuating band connected to a closed loop servo-system.

For purposes of illustration, the embodiment of the invention of Figs. 1 and 2 is shown arranged to actuate a tape driving mechanism 10 as for example in an electronic computer (not shown). One end of an actuating band 11, which may be a flexible steel band, is connected to a first arm 13 rigidly attached to a pivot 15. An idling roller 17 is carried at the outer end of a second arm 18 rigidly attached to the pivot 15 and is disposed adjacent the periphery of a tape driving wheel 19. A strip of magnetic tape 21, which is to be intermittently fed through the computer, passes between the periphery of the driving wheel and the idling roller so that when the arm 13 is rotated about pivot 15 in a clock-wise direction as viewed in Fig. l, the tape is forced into driven relationship 'with the driving wheel.

The arm'13 is biased in a counter-clockwise direction (as viewed in Fig. 1) by means of a tension spring 23 attached to the first arm. Several turns of the actuating band are loosely wrapped around a rotatable power drum 25 adapted to be driven at a high rate of speed around a shaft 26 by any suitable driving means (not shown). The end of the actuating band remote from arm 13 is connected to a clapper 27 provided on a conventional clapper-type solenoid 28. A circuit 30 for applying an electrical signal to the solenoid is-shown schematically as a battery 31 and an off-on switch 32. However, the solenoid may be arranged to receive a signal from any-kind of electrical circuit such as that employed to control the movement of magnetic tape in a computer system. 7 .1

The operation of the apparatus of Figs. 1 through 2 is as follows: With the solenoid not energized as shown in Figs. 1 and 2, the actuating band is loosearound the power drum and arm 13 is in the position illustrated, so that the magnetic tape is not'forced against the driving wheel. In order to cause magnetic tape to be delivered to a computer, the switch is closed (i.e., a signal calling for magnetic'tape is applied to the solenoid) and the clapper is pulled in a downward position. The clapper pulled snugly around the power drum. The friction between the power each power drum to cause drum and the actuating band is sufiicient to apply a strong downward force on the first arm 13 for the shaft 15 to cause the idling roller to move the tape into driven contact with the driving wheel. When the energizing signal is removed from the solenoid, the clapper returns to-its original position so that the band is no longer in driven relationship with the drum, and the spring 23 returns the pivot 15 to the position shown in Fig. 1 so that the magnetic tape is not longer driven.

Using the arrangement shown in Figs. 1 and 2., an 8 pound load was moved .005 inch in an operate time of 3 milliseconds and the same load was released in 1.7 milliseconds. This performance is more than ample for use in conventional computer systems employing magnetic tape.

The arrangement shown in Figs. 3 and 4 may be used where relatively long power strokes are required. In this embodiment an actuating band 35 is loosely wound around a rotatable power drum 37 adapted to be driven by a power shaft 39 turned by any suitable means (not shown). One end of the actuating band is connected to a load shown schematically as a tension spring 40, the other end of the band is fastened to a light-weight take-up spring.

An idling roller 41 is disposed adjacent the power drum periphery and is connected to the outer end of an arm 42 carried by a clapper 43 of a conventional clapper-type solenoid 44. A circuit 45 shown schematically as a battery 46 and an off-on switch 47 is connected to energize the solenoid intermittently.

In the position shown in Fig. 3, the solenoid is in a deenergized condition and the idling roller is not pressing the actuating band against the power drum. When the solenoid is energized, the clapper forces the roller against the actuating band which in turn is forced into driven relationship with the power drum. Thus, the load may be moved through a relatively large distance almost instantaneously and independently of the length of travel of the clapper.

Fig. illustrates another arrangement in which a load can be moved almost instantaneously through a relatively longdistance independent of the length of travel of the clapper. An actuating band 48 in the form of an endless belt is loosely disposed around a rotatable power drum 49 and an idling drum 50. The power drum is constantly rotated in a clock-wise direction as viewed in Fig. 5 by any suitable driving means (not shown). A projection 51 on the band located between the two drums is connected to a load illustrated schematically as a tension spring 52. An idling roller 53 is connected by an arm 54 to a clapper 55 of a conventional clapper-type solenoid 56 disposed adjacent the actuating band and arranged to be intermittently energized by a circuit 57 shown schematically as a battery 58 and an off-on switch 59.

When the solenoid is energized, the idling roller is forced against the actuating band to remove the slack from the band so that the band is forced into driven relationship with the power drum.

The embodiment of Fig. 5 may also be arranged with the solenoid adjacent the power drum periphery so that when the solenoid is energized, the idling roller forces the actuating band against the power drum.

Fig. 6 shows another embodiment of the invention for moving a load in either one of two directions. A first power drum 61 is arranged to rotate in a counter-clockwise direction, as viewed in Fig. 6, and a second power drum 62, spaced from the first, is arranged to rotate in a clockwise direction. An actuating band 63 in the form. of an'endless belt is loosely wound around each of the drums with several turns. One end of a mechanical link 65 is rigidly attached to this band and the other end of the link is connected to feed mechanical movement to a. load or movable mass 66 in a closed loop servesystem 67 shown schematically in block form. The closed loop servo-system may be a recorder using the self-balancing potentiometer principle, a plotter, a computer system, or the like.

A first conventional clapper-type solenoid 68 is disposed adjacent the band between the mechanical link and the first power drum. A first idling roller 69 carried by an arm 70 connected to a clapper 71 of the first solenoid is arranged to take the slack out of the band between the load and the first power drum when the first solenoid is actuated and thus cause the band to move upwardly. A second conventional clapper-type solenoid 73 is disposed adjacent the actuating band between the link and the second power drum. A second idling roller 75 is carried by an arm 76 connected to a clapper 77 of the second solenoid and arranged to take the slack from the band between the link and the second power drum when the second solenoid is actuated. Each solenoid is electrically connected to receive appropriate signals from the closed loop servo-system. Thus, when the closed loop servo-system calls for the link to be moved up, the first solenoid is actuated and the link moves up until the servo-system is balanced and the first solenoid is deenergized. If the closed loop servo-system calls for the load to be moved downwardly, the second solenoid is energized and the link is moved down until the system is once again balanced and the second solenoid is deenergized.

In all of the above arrangements the tape is shown being forced into driven relationship when the solenoid is energized, i.e., supplied electrical power. However in any of the above arrangements, the clapper of the solenoid may be spring loaded so that the tape is held in driven relationship until the solenoid is energized and the clapper overcomes the action of the spring to release the band from driven relationship. With either arrangement the invention provides means for converting a relatively small electrical signal and a correspondingly small mechanical movement of a light-weight element into a relatively large amount of mechanical power almost instantaneously with the generation of the electrical signal.

I claim:

1. A mechanical power amplifier for applying power to a load in either one of two directions comprising a first power drum, means for rotating the first power drum continuously in one direction, a second power drum, means for rotating the second power drum continuously in the opposite direction from the first drum, an actuating band disposed around-the drums, and adapted to be connected to the load, a first solenoid having a plunger arranged to move the band into driven relationship with the first drum when the first solenoid is actuated, and a second solenoid having a plunger arranged to move the band into driven relationship with the second drum when the second solenoid is actuated.

2. A mechanical power amplifier for applying power to a load in either one of two directions comprising a first power drum, means for rotating the first power drum continuously in one direction, a second power drum, means for rotating the second power drum continuously in the opposite direction from the first drtun, an actuating band disposed around the drums, and adapted to be connected to the load, a first solenoid having a plunger arranged between the load and first drum to move the band into driven relationship with the first drum when the first solenoid is actuated, and a second solenoid hav- 7 ing a plunger arranged between the load and second drum to move the band into driven relationship with the second drum when the second solenoid is actuated.

3. A mechanical power amplifier capable of high speed control for amplifying power to a load comprising a rotatable power drum, an actuating band disposed around the drum, a support, a spring connected to the support, one end of the band being connected to the spring and adapted to be connected to the load, and'a fast acting solenoid having a lightweight movable plunger connected to the other end of the band to vary the strain on the band and move the band into and out of driving relationship with the drum when the solenoid is actuated.

References Cited in the file of this patent UNITED STATES PATENTS 377,413 Smith Feb. 7, 1888 6 Nieman Mar. 25, 1930 Gretener et a1. Feb. 26, 1952 Minorsky Mar. 18, 1952 Marek Jan. 20, 1953 FOREIGN PATENTS France Jan. 5, 1930