US1768625A - Refrigerating apparatus - Google Patents

Description

y 1930- Q o. c. OLSEN 1,768,625

REFRIGERATING APPARATUS Filed March 30, 1929 Patented July 1, 1930 UNITED STATES PATENT OFFICE OLAI' C. OLSEN, OF DAYTON, OHIO, ASSIGN OB TO FRIGIDAIRE CORPORATION, 0]? DAY- TON, OHIO, A CORPORATION OF DELAWARE BEFBIGERATING APPARATUS Application filed March 30, 1929. Serial No. 851,287.

This invention relates to refrigerating apparatus and particularly to arrangements for controlling the circulation of refrigerant in such a paratus.

One 0 the objects of the invention is to provide an improved control device particularly adapted to multiple installations which automatically prevents the circulation of refrigerant in such unit or units of the system as do not need refrigeration.

Another object of the invention is to provide an improved refrigerating system in which one condensing element supplies a number of evaporating elements with refrigerant and automatically maintains each of them within predetermined temperature limits independent of the remaining elements.

More specifically it is an object to provide an improved form of automatic control valve for positivel closing the outlet of an evaporator when t ere is no refrigerating demand upon such evaporator.

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

In the drawings:

Fig. 1 is a diagrammatic representation of one form of refrigerating system embodying my invention,

Fig. 2 is a control valve, partly in section and partly in elevation,

Fig. 3 1s a plan view of a portion of the valve,

Fig. 4 is a section on the line 44 of Fig. 3,

Fig. 5 is a section on the line 5-5 of Fig. 3,

Fig. 6 is a section on the line 6-6 of Fig. 3, and

Fi 7 is a section on the line 77 of Fig. 3.

It has previously been proposed to provide a number of-evaporators which are supplied with refrigerant from a common condensing element and to operate the system so as to maintain the different evaporators at different temperatures. 1 In the usual systems of this character the different evaporators are not' entirely independent of each other and the condensing element does not circulate refrigerant through the various evaporators in accordance with the refrigerating demand upon each. The difficulties experienced have been the more pronounced in cases in which it is sought to maintain widely different temperatures. My invention is concerned with providing a simple, economical and improved control valve which will satisfactorily maintain widely different temperatures and which will enable the various refrigerating elements to be operated independently of one another.

Referring to the drawing 10 designates in general a condensing element for withdrawing gaseous refrigerant from a vapor conduit 11, liquefying the refrigerant and delivering it to a liquid supply conduit 12. The condensing element may be of any desired type, for example it may include the usual motor 14, compressor 15 and condenser 16, the motor being actuated in response to the pressure within the conduit 11 by means of an automatic switch 18 which connects the motor to power mains 19. Evaporators 20 and 21 are connected in parallel between the liquid supply conduit and the vapor exhaust conduit 11 for cooling compartments 20 and 21. The evaporators are connected to the conduit 11 by means of independent outlet conduits 23 and 24. Preferably each of the evaporators is of the flooded type and includes a reservoir for liquid .refrigerant which is kept at a constant level therein by means of a float valve, not shown herein, but fully disclosed in the patent to Osborn 1,556,708, October 13, 1925. Since the evaporators are of the flooded type, the pressure of the refrigerant in each will correspond to its temperature. Assuming that the evaporator 21 is to be kept at the higher temperature and pressure, I place in the outlet of this evaporator a shut-off valve 26, the construction of which is illustrated in Figs. 2 to 7, and which automatically closes when the evaporator 21 has reached a predetermined low pressure. A valve casin 30 having an inlet 31, an outlet 32, and a ore 33 is connected between the conduit 24 and conduit 11. Within the casing is a valve seat 27 and a valve proper which is either raised to permit unrestricted communication between the inlet and outlet, or else is lowered against the seat to positively close the outlet, by means about to be described. To the casing is sealed the open end of a flexible metal bellows 35, the other end of which is closed in any suitable manner. Preferably the bellows is closed at its upper end by a cap 36 soldered to the bellows and its lower end is soldered to an end cap 37 secured to the easing in any suitable manner. The bellows form a motor for operating the valve 25 in response to the pressure within the casing 30 thru an actuator 39.

The actuator or rod 39 is rigidly secured to the bellows cap 36 and extends down into the bellows where it has a lost motion connection with the valve 25. This is preferably formed by a bore 40 which receives a reduced portion 41 of the valve stem, the bore having a slot 42 in its wall to receive a pin 43 in the valvestem. The valve is normally prevented from movement by a pair of friction shoes 48 urged outwardly against the bore 33 by a spring 49. There is sufficient clearance between the valve stem and bore to permit the pressure in the bore to be freely communicated to the bellows, the bore however serving as a guide for the valve.

The rod 39 extends above the cap 36 and at its upper end has a reduced portion 50 on which a nut 51 clamps cam members 52 and 53. Each of the cam members, as shown in Figs. 3 to 7, is preferably provided with a number of radial lugs, arranged in pairs. Each pair has oppositely disposed faces of the same slope, and the slope of the pairs is different.

Thus in Fig. 4, the faces have a relatively small inclination to the vertical, while the inclinations of the pairs of faces 61, 62 and 63 progressively increase.

A pair of cam followers are pivoted to lugs 71 on a frame 72 secured to the valve casing. The followers have rollers 73 which are urged a ainst the cam faces by a pair of springs 75 and a tie rod 76 whose effective length can be varied to adjust the tension of the springs by nuts 78.

The valve operates as follows. In the position shown in Fig. 2, the valve is closed and is positively held closed by the pressure of the cam followers on the cam 52. As the pressure in the valve casing increases, the bellows expands gradually lifting the rod 39 and forcing the cam followers farther apart, increasing their potential energy stored in the springs 75. During this gradual movement, the slot 42 moves along the pin 43, the valve remaining stationary due to the pressure in the casing and the friction shoes 48. At a predetermined point in the expansion of the bellows the cam followers reach the dividing line between the cam 52 and cam 53, and substantially all of the lost motion in the connect-ion 42-43 has been taken up. Any further expansion of the bellows, however slight, brings the cam 53 under the followers, and the springs 75 force the followers toward each other, giving up energy to the cam 53, and suddenly snapping the rod 39 to its extreme position. The force of the cam followers overcomes the friction of the shoes 48 and suddenly opens the valve. Thereafter a gradually decreasing pressure gradually lowers the rod 39 until the edge of the cam 52 is reached, the valve meanwhile being held open by the friction shoes. Thereafter the valve is suddenly snapped closed by any further slight movement of the bellows.

The cam 52 is termed the closing cam and the cam 53 the opening cam because they perform these functions respectively. The closing cam 52 receives energy from the cam followers on closing, but imparts energy to them on opening. cam receives energy from the followers when opening, but increases their energy, or imparts energy to the followers when the valve is being closed. Because one cam receives energy when moving in one direction, and the other cam delivers energy when moving in the same direction, the slope of all the faces of one cam is considered positive while the slope of all-the faces of the other cam is considered negative. I

The cams can be independently removed to permit the substitution of cams of different pitches, or the cams can be independently rotated to present faces of different pitches to the followers. By properly selecting the slopes of the positive and negative cams, the interval between the opening and closing pressures can be variedaccording to requirements, while the absolute values of both opening and closing pressures can be coordinately increased or decreased by suitably adjusting the tension of the springs 75.

The automatic switch 18 is set to operate at low pressures corresponding to the temperatures to be maintained in the evaporator 20. Whenever the temperature of 20 is above the maximum permissible value, the pressure of the refrigerant will actuate the switch 18 to operate the condensing element. Under these conditions refrigerant will not be evaporated in the evaporator 21 unless the valve 26 is open. VVheneverthe valve is open, the condensing element will reduce the pressure and temperature of the evaporator 21 to its lowest permissible value (which is above the setting of the switch 18) at which point the valve will close to prevent further refrigeration in 21. If the evaporator 20 should at any time be within its normal temperature limits, and the condensing clement consequently be idle, and the evaporator 21 should become too warm, the pressure in 21 will open the valve and allow the high pres- Conversely the opening sure to be communicated to the. conduit 11 and switch 18. Since this hi h pressure is above the value which closes t e switch, the switch will be operated immediately to start the condensing element. Refrigerant will then be withdrawn from both evaporators until both have reached their minimum permissible temperature. If the evaporator 21 reaches its minimum temperature first, the

valve 26 will close to prevent further refrigeration, and the condensing element will continue to refrigerate the evaporator 20. If, however, the evaporator 20 should reach its minimum temperature first, the valve will remain open, and the. pressure of the refrigerant evaporated in 21 will keep the switch open. However, since each evaporator con tains a relatively large quantity of liquid rerefrigerant, whose pressure corresponds to its temperature, the rates of evaporation of the liquid will correspond with the pressures. Hence refrigerant will be evaporated rapidly in 21 and quickly reduce its temperature, whereas refrigerant will be evaporated but slowly in 20, and thus its temperature will not be reduced to a value appreciably below its normal minimum value.

\Vhile the form of embodiment of the 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 follow.

What is claimed is as follows:

1. A snap-acting control device comprising in combination an actuator adapted to move between two extreme positions in response to gradual changes in a condition to be controlled, a control element having two posi tions, and means for moving the element suddenly from one position to the other including a lost motion connection between the actuator and element, a cam of positive slope and a cam of negative slope on the actuator, and a cam follower, the cam of positive slope being adapted to increase the potential energy of the cam follower during movement of the actuator in a given direction and the cam of negative slope being adapted to receive energy from the cam follower during further movement in the same direction, and the cam of negative slope being adapted to increase the potential energy of the cam follower durin movement in the opposite direction, and t e cam of positive slope being adapted to receive energy from the cam follower during further movement in said. opposite direction, said cams being independently removable.

. 2. A snap-acting control device compris ing in combination an actuator adapted to move between twoextreme positions in response to gradual changes in a condition to be controlled, a control element having two positions, and means for moving the element suddenly from one position to the other including a lost motion connection between the actuator and element, a cam of positive slope and a cam of negative slope on the actuator, and a cam follower, the cam of positive slope being adapted to increase the potential energy of the cam follower during movement of the actuator in a given direction and the cam of negative slope being adapted to receive energy from the cam follower during further movement in the same direction, and the cam of negative slope being adapted to increase the potential energyof the cam follower during movement in the opposite direction, and the cam of positive slope being adapted to receive energy from the cam follower during further movement in said opv posite direction, said cams having portions of different slopes and beingindependently adjustable to vary independently the positive and negative slopes presented to the cam follower.

3. A snap-acting control device comprising in combination an actuator adapted to move between two extreme positions in response to gradual changes in a condition to be controlled, a control element having two positions and means for moving the element suddenly from one position to the other includtuator and the element, a cam on the actuator, and a cam follower, said cam having portions of different slopes and being adjustable on said actuator to present different portions to said cam follower.

4. A snap-acting control device comprising in combination an actuator adapted to move between two extreme positions in response to gradual changes in a condition to be controlled, a control element having two positions and means for moving the element suddenly from one position to the other including a lost motionconnection between the actuator and the element, a cam on the actuator and a cam follower, said cam having 'of pairs of opposed faces, the slope of the faces in each pair being the same and the slopes of the pairs being different, and a pair of cam followers adapted to cooperate with opposed faces, said cam being adjustable to present different pairs of faces to the camfollowers.

6. A snap-acting control device comprising in combination an actuator adapted to move ing a lost moti'on connection between the acbetween two extreme positions in response to gradual changes in a condition to be controlled, a control element having two positions and means for moving the element suddenly from one position to the other including a lost motion connection between the actuator and element, a cam having opposed faces,.=a" pair of cam followers adapted to cooperate with the faces, means for urging the cams against the faces and means for equalizing between the two followers the pressure on the cams.

7. A snap-acting control device comprising in combination an actuator adapted to move between two extreme positions in re sponse to gradual changes in a condition to be controlled, a control element having two positions, and means for moving the element suddenly from one position to the other including a lost motion connection between the actuator and element, a cam of positive slope and a cam of negative slope on the actuator, and a cam follower, the cam of positive slope being adapted to increase the potential energy of the cam follower during movement of the actuator in a given direction and the cam of negative slope being adapted to receive energy from the cam follower during further movement in the same direction, and the cam of negative slope being adapted to increase the potential energy of the cam follower during movement in the opposite direction, and the cam of positive slope being adapted to receive energy from the cam follower during further movement in said opposite direction, said cams being independently adjustable to vary the interval between the maximum and minimum values of the condition to be controlled, and means for coordinately adjusting the maximum and minimum values to be controlled including means for varying the resistance to movement offered by said cam follower.

8. A snap-acting control comprising in combination a movable actuator having two extreme positions and being adapted to move gradually from one extreme position to a predetermined point in response to gradual changes in a condition to be controlled and to move suddenly from said predetermined point to the other extreme position, a movable controlelement having a lost motion connection with the actuator and friction means for normally preventing movement of the control element, said actuator beingadapted to overcome said friction means.

9. A snap-acting control comprising in combination a movable actuator having two extreme positions and being adapted to move gradually from one extreme position to a predetermined point in response to gradual changes in a condition to be controlled and to move suddenly from said predetermined point to the other extreme position, a movable control element having a lost motion connection with the actuator, a guideway for the control element, a friction shoe carried by the control element and a sprin for urging the friction shoe into contact wiai the guideway.

10. A snap-acting control device comprising in combination an actuator adapted to move between two extreme positions in response to gradual changes in a condition to be controlled, a control element having two positions, and means for moving the element suddenly from one position to the other including a lost motion connection between the actuator and element, a cam of positive slope and a cam of negative slope on the actuator, and a cam follower, the cam of positive slope being adapted to increase the potential energy of the cam follower during movement of the actuator in a given direction and the cam of negative slope being adapted to receive energy from the cam follower durin further movement in the same direction, and the cam of negative slope being adapted to increase the potential energ of the cam follower during movement in the opposite direction, and the cam of positive slope being adapted to receive energy from the cam follower during further movement in said opposite direction, said cams being independently removable, and means for normally preventing movementof said control element, said actuator being adapted to overcome said means.

1].. A snapwacting control device comprising in combination an actuator, a pressure responsive motor adapted to move the actuator between two extreme positions in response to gradual changes in pressure, a control element-having two positions and means for moving the element suddenly from one position to the other including a lost motion connection between the element and the actuator, friction means normally preventing movement of the element, the actuator being adapted to overcome the friction means, an opening cam and a closing cam on the actuator, each of said cams having a plurality of pairs ofopposed faces, the faces in each pair having the same slopes and the slope of the pairs being different, a pair of cam followers, means for urging the followers into contact with opposed faces, means for equalizing between the cam followers the pressure on the faces, the cams being adjustable to present different-facesto the cam followers to adjust the interval between the pressure at which the motor moves the element to one extreme position and the pressure at which the motor moves the element to the other extreme position, and means for adjusting pressure of the cam followers on the cams to coordinately vary said pressures.

In testimony whereof I hereto aflix my signature.

OLAF C. OLSEN.

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