US1732464A - Control system - Google Patents

Description

W. FOURNESS CONTROL SYSTEM Oct. 22, 1929.

Filed July 28. 1926 INVENTOR m /f/ ed Eur/4355 BY Z/YM/ d lfis ATTORNEY Patented Oct. 22, 1929 UNITED STATES,

PATENT OFFICE WILFBED FOUR-HESS, OF PASADEI I'A, CALIFORNIA, ASSIGNOR, BY MESNE ASSIGN- KENTB, TO THE FOURNESS DEVELOPMENT CORPORATION OF NEW,YOBK, N. Y., A

CORPORATION OF NEW YORK con'rnor. SYSTEM This invention relates to an electrical control system, and especially to one that is adapted to control the operation of a mechanical refrigerating plant.

In the usual type of mechanical refrigeration, use is made of a fluid refrigerant, which absorbs heat as it is allowed to expand under low pressure, in an expansion chamber orcoil.

Mechanical work can then be performed on tial vacuum so produced, ensures rapid expansion and consequent rapid cooling. In

small installations, such as in connection with domestic ice boxes or with store display cases, the operation of the compressor to maintain a low pressure need be only intermittent, there being a sufficient vacuum maintained for an appreciable time even when the compressor is shut down.

It has been proposed to operate the compressor automatically in accordance with the pressure existing in the expansion space; but such prior schemes are cumbersome and expensive. It is accordingl one of the objects of my invention toprovi e a compressor control that is' simple and reliable.

In connection with such schemes for controlling the compressor, it is obviously advantageous to arrange the mechanism so that it will not be set into operation for eve slight variation in pressure,but instead, there shouldbe limits of pressure between which the'control mechanism is inactive. It is thus Application filed July 28, 1926. Serial No. 125,460.

another object of my invention to make it possible not only to provide limits of pressure between which the control is inactive, but also to adjust these limits.

In order to provide such a control system, a pressure responsive device must be used; and it is another object of my invention to provide a novel, simple, and rugged device of this character.

My'invention possesses many other advantages, and has other objects which may be ma e more easily apparent from a consideration of one embodiment of my invention. Fon this purpose I have shown a form in the drawings accompanying and forming part of the present specification. I shall now proceed to describe this form in detail, which illustrates the general principles of my invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of my inventioni isbest defined by the appended claims.

Referring to the drawings:

Fig. 1 is'a side elevation, with some of the parts broken away, of a pressure responsive device for controlling the compressor in the refrigerating system;

F i g. 2 is a top plan view thereof;

Fig. 3 is a reduced size fragmentary side elevation similar to Fig. 1 and showing an alternate position of the apparatus; I

Fig. 4 is a sectional detail taken along plane 44 of Fig. 2; and

Fig. 5 is a fragmentary view taken along. plane 5-5 of Fig. 1. I

Thecompressor of a refrigerating system can He controlled so as to start operation only when the pressure, in an expansion space reaches a high value. In this way the pressired limits.

In order to control the operation of the W P, 7 1n the expansion chamber, I provide a device sure of'the refrigerant is reduced to the deessor in response to'pressure variations cuits for the motor that operates the comby a large longitudinal expansion and con-' pressor.

In this device, I provide aflexible chamber 28, the shape of which alters upon variations in pressure, the alteration bein utilized to provide a controlling function. he chamber28 is preferably made from thin copper folded into accordeon or bellows form, wheretraction of the chamber can be efiected even for comparatively small variations in the gas pressure within the chamber. In the present instance, the upper end of chamber 28 is entirely closed, and forms the movable end.

The lower end is stationary, and .is held to a supporting :plate 29 at the central hub porezo tion 30. This hub portion has-an extension .31 which has external threads for accommodating a clamping nut-32, engaging the bottom of plate 29 and clampin this'plate betvgeen it and the hub 30. T e extension 31- also has an internall threaded a erture, communicating with t e interior of 'llows 28 and accommodating a pipe, connection 33 which can be connected to the expansion space under control. w I

As thus far described, it is evident thatv upon an increase in this instance as integral with a plate 37, held the coin actness of the operating mechanism rigidly-fin spaced relation from plate 29, as .by the shouldered bolts 38;

The upper end of rod 34 carries a device for 1 operating electrical contacts. One of the important features of thi invention resides in and'of t e contacts. For example one set of contacts are supported by the rod-34, while the cooperating set is operated by' the rod to engage the first set. For this purpose, rod 34 carries an insulationblo'ck 39, at the top end 1 clearl of which there are a pair of metal contact clips 40 and ,41. These clips are shown most in Fig. 5. They can be fastened to the si esof block 39 by the aid of the integral flatextensions41', and screws 42. One ofthese screws for each'clip 40, 41 can serve also to hold a'lead wire 43 to the extension 41'. The wires 43 are in series with the motor 1 circuit, and it is only when the two clips 40 i d 41 are in electrical. contact that themctiiating'motor can be energized.

The connecting devicesfor effecting this result include a pair of switch blades 44 and 45.' 'These blades are supported, one on-each side of an insulation support-46, to which the blades are fastened as by screws 47. The blades '44 and 45 are moreover in electrical contact, as by the aid of a wire connector 48, whereby when the blades enter between the clips .40 and 41, they serve to complete the-circuit between the clips.

For permitting this blade movement, as

shown in Fig. 3, apivotal mounting for the blades is provided, as for example by the aid of a post49, heldto plate 37 by nut 50, and provldinga fork at its upper end. Between the arms of the fork is pivoted a bar 51 that is screwed or otherwise. fastened into the block 46. s l

The'movement of rod 34 upwardly serves to tilt the blade assembly about the pivot of bar 51. For this purpose, blade44 has a projection extending entirely across the block 39, and is in the path of travel of a pin 52 that is fastened in the block 39. As the rod 34 travels upwardly due to the expansion of chamberj28, blade 44'is lifted, until a central position is reached, beyond which the blades are rapidly snapped over into the position of Fig.' 3. In order to accomplish this sna -over'action, a spring arran ement.

is provi ed that will now be describe As clearly shown in Fi 2, bar 51 carries a transverse rod 53, notc ed adjacenteach end for anchorin .the tension springs 54. The other ends o the springs are similarly anchored to rods 55. These rods 55 stay stationary while the rod 53 moves in accordance' with the movement of blades 44 and 45. It is evident-that, rod 34 moves'upwardly from the position of Fig. 1, the first effect is a stretching of both springs 54; and this stretching continuesuntil the axis of the springs as viewed in Fig. 2 passes through the pivot of bar51. As soon as this central position is passed ever so slightly,

the springs 54"act with a snap to complete the counterclockwise movement of blades 44 and 45. 1

The final result is illustrated in Fig. 3, the blades 44 and- 45 engage the clips 40 and 41, and contact is made, causing operation of the compressor. Although rod 34 may continue to rise, yet blades-44 and 45 would maintain contact with clips 40-and 41, due to the tension of springs 54, exerting a resilient lifting force to t ese blades.

It is evident that before the springs 54 can be active to produce the snap-over action described, chamber 28 must, expand to a definite size, and this in turn-means that a definite limiting high pressure. must be reached in the expansion space of the refrigerating system. A pair ofcentralizing compression springs 56 and 57 are used on rod 34, which are unflexed just atthe 'point of sna -over. In this way, sprin be ma e rather light, as substantia ly all the work they have to do is to move the blades 54 can It is evident that if the tension of springs 54 could be adjusted, such an adjustment would influence the amount of pressure that must be present in chamber 28 to accomplish the controlling function. When the tension is greater, a larger pressure must exist to operate the blades; and vice versa. In order toprovide such an adjustment, rods 55 are movable in a direction substantially parallel to the axis of the springs, as for example, by being mounted on a nut 58. This nut, as clearly shown in Fig. 4, is arranged to traverse a thumb screw 59. This screw can be turned in one direction to move rods 55 against the tension. of springs 54, or else turned in the other direction to permit 'the rods 55 to be pulled by the springs 54.

The thumb screw 59 is kept in position by a pin 60 which extends into an aperture in the screw, and is fastened to the top of a stationary post 61. The tension of springs '54 also assist in holding the end ofscrew 59 tightly against this post.

The operation of opening the contacts is accomplished in a manner entirely analogous to that of closing them. The blade 44, as

shown most clearly in Fig. 3, can be engaged by the head of one of the screws 42, so that when rod 34 moves downwardfthe blade 44 is also urged downwardly. Thus upon a suflicient contraction of the bellows chamber 28,

the springs 54 are again snapped over center and the mechanism takes the position of Fig. 1. Due to the sna over action, a large current can be broken y the contacts withoutmaterial danger of injurious arcing or sparking. It is also evident that an increase in tension of springs 54'by adjustment of screw 59, causes the apparatus to' open the The manner of operation of this system is probably self-evident from the foregoing. When the refrigerating system is operat ng and the pressure is low in an expanslon space, the motor is de-energized, and the compressor is idle. As soon as a definite 'pressure is reached, the apparatus 26 operates to close the contacts, and the compres-' sor is set into operation. The operation continues until a definite, low pressure is reached, when the contraction of bellow chamber 28 will urge rod34 downward to open the contacts. The cycle can then be repeated.

I claim: 1. In a pressure responsive device, a member movable in accordance with the pressure that is to operate the device, 'a contact carried by said member, a pivoted cooperating contact, arranged to be moved by said member in either direction, and a spring for snapping the said cooperating contact in by said rod, a cooperating pivoted contactarranged to be moved by said rod so as to move it toward and away from saidfirst contact, and a spring for snapping said pivoted contact in either direction upon suflicient movement of the rod.

3. The combination as set forth in claim 2, with means for adjusting the tension of the spring, comprising a pin, a hollow screw \guided on the pin, and'a nut on the screw to which the spring is connected.

4. In a pressure responsive device, a bellows-like container arranged to expand and contract in accordance with the variations in pressure therein, means supporting one end of the container, a rod, attached to the other end in a direction parallel with the expanding and contracting movement of the container, a guide for the rod, a contact supportedby the rod, a pivotally mounted cooperating contact structure arranged to .be moved in either direction by the rod as the container expands and contracts, a spring anchored to the contact structure at a point remote from the pivot, and an anchor for the other end of the spring, located in such a place that the spring serves to snap the contact structure in either direction upon sulficient movement of the rod.

5. The combination as set forth in claim 4, with the addition of means for adjusting the pressure of the spring.

6. In combination, a movable operating member, a contact supported rigidly thereon, a pivoted cooperating contact arranged to be moved by said member in either direction. and a resilient member for snapping the said cooperating contact in either direction upon sufiicient movement of said member.

7. In combination, a contact structure pivoted for movement, resilient means for snapping said structure in either direction about its pivot, and an actuator member for moving said structure, comprising a rod having a pair of spaced abutments for engaging the structure when the rod is moved, and a contact member rigidly fastened to said rod and cooperating with said contact structure.

8. In combinatiom'a contact structure pivoted for movement, said structure including a pair of spaced blades, resilient means for snapping said structure in either direction about its pivot, a movable actuator for said structure, the spaced blades being arranged to permit said actuator to pass between them, and a pair of contact clips carried one on each side of the actuator for cooperating with said blades.

9. The combination as set forth in claim 8, with the addition of actuating pins carried by the actuator and arranged to coact with at least one of the spaced blades for moving the contact structure and for defining the limits of movement. 7

' In testimony whereof I have hereunto set my, hand.

. "WILFRED FoURNEss.

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