US1673218A - Automatic control for refrigerating systems - Google Patents

Description

June 12, 1928. 1,673,218 F. R. ZUMBRO AUTOMATIC CONTROL FOR REFRIGERATING SYSTEMS Filed June 22, 1926 3% new '01,

% HankRZumbm Patented June 12, 1928.

UNITED STATES FRANK R. ZUMBRO, OF WAYNESBORO, PENNSYLVANIA, ASSIGNOR TO FRICK COMPANY,

OF WAYNESBORO, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

AUTOMATIC CONTROL FOR Application filed June 22,

My said invention relates to a refrigeration system with automatic controlling means, preferably electrically operated, whereby the temperature in any number of compartments in a direct expansion system may be individually controlled.

It is an object of my invention to adapt a suction pressure regulating device to automatic refrigerating plants with particular reference to its use in connection with multiple control on the direct expansion system using any refrigerant, which in its cycle of operation, alternately passes through a state of vapor or liquid.

A further object is to maintain a relatively constant suction pressure within the limits of the apparatus when the compressor is in operation thereby eliminating the use of an automatic suction pressure regulated expansion valve.

Another object is to provide means whereby the compressor motor may be started and at the same time prevent the admission of refrigerant into the evaporating system until the pressure within said system has been pumped down or reduced to a certain degree thereby eliminating all danger of flooding the system or drawing any of the liquid refrigerant into the compressor.

Another obejct is to provide means whereby the control of the liquid ammonia to the evaporating system is such that a magnetically operated valve or motor operated valve may be used for shutting off the supply of 21 refrigerant to each cooling coil in each refrigerating compartment, and so installed that warm liquid will always be on both the inlet and outlet side of the valves and preventtheir freezing.

Referring to the accompanying drawin s, which are made a part hereof and on which similar reference characters indicate similar parts,

The single figure represents a diagrammatic plan view of the system in which the motor, compressor, valves, switches, etc. are of conventional construction.

In the drawings reference character 10 indieates a motor connected by a belt 11 to a compressor 12 of any approved design suitable for the purpose. The liquid refrigerant, which may be ammonia or any other desired refrigerant, passes from the receiver 125 through a pipe 14 and its branch pipes. each having a magnetic shut-off valve 15 REFRIGERATING SYSTEMS.

1926. Serial No. 117,824.

and a hand set expansion valve 16 communicating with a. cooling coil 17 in each freezing or cooling compartment. A common return suction pipe 18 connects all of the cooling coils 17 to the suction side of the compressor 12. The gas is compressed as is well known in the compressor 12 and passes to the condenser 66, wherein it is converted from a gas to a liquid and in this form passes to receiver 13. lVhile I have shown three refrigerating units connected in parallel by the pipe 14 and return pipe 18, obviously any number of units may be used. An electric contact gauge 19' is connected to the suction pipe 18 by means of a pipe 20 andwill be hereinafter more fully described. 7

Each freezing compartment is equipped with a double pole single circuit mercury tube thermostat 21, of the type which is either on the on or the off position, each tube being mounted on the same shaft and adapted to operate simultaneously responsive to the temperature. As shown, the upper tubes 22 control the starting and stopping of the compressor motor 10 while the lowertubes 23 control the circuit to the magnetic shut-off valve 15. The electric connections are arranged in parallel and the motor 10 will remain operating as long as any one thermostat 21 isfin the on position and will only stop when all thermostats are on the off position, each valve 15 being independently controlled by its own thermostat When all of the thermostats 21 are on the on position, the current flows from the right hand side of the main line 24 through switch 25 to thelive side of an automatic starter and circuit breaker 26 of a well known type, through. wire through fuse block 27, and high pressure cut-out 28. to the upper tube 22 through conductor 29 and 1 branches 29,-through snap switches 30 in each cooling compartment, then through wire, 31 to terminal 32 of the starter 26, and through the overload contacts 62 through the low voltage coil 59 of the starter to a manually operated snap switch 34 back to the main line 24, thus energizing the low voltage coil 59 which closes the circuit to the motor through the contactors 63 and the heating coils of the overload relay 33 to the motor, thus strating the motor 10 and compressor 12. Branch conductors 35 connect conductor I 29 also with the'lower tubes 23, from whence the current then passes through snap switch 64 to fuses 36 to the shut-off valves 15, and through conductor 37 to contact 38 of a relay 39 of a well-known type. It will be noted from the above that each tube 23 independently controls a shut-off valve 15.

Assuming that the pressure in pipe 18 is 14 pounds or less the arm .40 of the gauge 19 will contact with terminal 41 allowing the current to flow through conductor 42 to arm 40, and through the same to terminal .41, through a conductor 43 to terminal 44 then through a contactor 45, through a wire 46 to the upper winding 47 of a relay, and then through a conductor 48 to a power lead 49 which runs to the motorlO and to a terminal 50 in the automatic motor starter 26. The

closing of the circuit in winding 47 causes an arm 51 to swing into contact with a terminal 52 which also causes a lever 53 to close the circuit with a contact 54 and break the circuit between terminal 44 and contactor 45, thereby causing the current to flow from conductor 48 through arm 51 and contact 52 through conductor 37 which is the common return conductor for all of the shutoff valves 15. Relay 39 is of the lock up type, i. e., when once pulled in either direction, it stays in this position without the application of magnetic pull until the coil is energized to pull it into the other position where it remains until again energized in the original direction. With the circuit closed in the shut-01f valves 15 these valves are held open and the liquid refrigerant is allowed to flow through the valves to the coils. suction pressure has gradually increased to about 19 pounds, the arm 40 of the gauge contacts with a terminal 55 and the current then flows from conductor '42 through arm 40 to terminal 55 through conductor 40', to contact 54, through contactor 53 and con- ,ductor 56, through the lower winding 57 of the relay and conductor 48 to conductor 49 and terminal 50. The relay arm 51 is then moved to break the circuit with contact 52 which breaks the circuit from the shut-01f valves 15 and, allows them to close. This same action also breaks the circuit between 53 and 54 and allows 45 to again come in contact with 44. T he'valves 15 being closed, the flow of refrigerant is stopped and the machine then pumps down or reduces the pressure within the coils 1 7 and return pipe 18 to about 14 pounds when the. cycle of operation is automatically repeated.

In order to control the system manually instead of automatically by means of the mercury tube switches, a switch 58 is interposed in the line 31 which when in -ofi' position as shown, allows for automatic operation and when on permits manual operation by shunting the lines 31 and 29 by a conductor 59. Also for hand operation,

. bypass valves are provided for bridging When the compartment and the pressure of the evap-,

orating system. The valve to any one to the electric shut off valves,

compartment can not open unless the thermostat controlling it is on the on position, governed by the temperature of the compartment, nor can it open if the suction pressure is above a certain point. In view of the fact that the circuit of the shut-off valves can not be completed until the pressure in the suction line has been reduced to a certain degree, the apparatus provides means whereby the pressure in the evaporating system is automatically reduced or pumped down before any liquid refrigerant isadmitted to the system thereby eliminating the danger of pulling liquid refrigerant into the compressor. It is a well known fact that all shut off valves leak more or less and our arrangement obviates a gradual increase in liquid in the evaporator, especially when the plant is shut down and which accumulation of liquid finally reaches some magnitude as to cause great danger should it be pulled over into the ammonia compressor.

This circuit and apparatus permits the use of hand operated expansion valves 16 which should be set as nearly as possible to the pressure desired in the evaporating system but which does not need to be as accurate as in the case of hand operated systems for the reason that the flow of ammonia is under control of the pressure regulating device. By virtue of the use of a hand opperated expansion .valve on an automatic s stem, the shut-off valve only handles warm llquid or liquid which is above the freezing point thereby eliminating the possibility of the shut-off valves freezing.

It will be obvious to those skilled in the art that various changes may my device without departing from the spirit of the invention and therefore I do not limit myself to what is shown in the drawings and described in the specification but only as indicated. in the appended claims. Furthermore it is understood that a single device may be substituted for the combination 7 of gauge 19 and relay 52. The pressure device arranged to be either in the on position, or off position and passing over the interval between the two positions with a snap action.

Having thus fully described nay vention, what I claim as new an said indesire to secure by Letters Patent, is:

1. The combination in-arefrigerating Sys Ill) be made in tem of a cooling coil, a compressor and condenser for supplying refrigerant. to said coil, a manually controlled expansion valve for controlling the supply of refrigerant to the coil, a magnetic or motor operated shut-elf valve between said manually operable valve and said compressor, a motor-for operating said compressor, a pressuregauge operated by suction maintained by the compressor in the refrigerating coils, a thermostatically controlled double pole switch for interrupting the current to said shut off valve and to said motor, and .a relay associated with said pressure gauge adapted to remain in one position during a given pressure interval and being adapted to be shifted to another position when the pressure has varied a predetermined amount for controlling the operation of the magnetic valves, substantially as set forth.

2. The combination in a refrigerating system includinga compressor and a condenser, refrigerating coils for receiving refrigerant from the compres3or, a motor for operat-' ing the compressor, magnetically controlled valves for controlling the supply of refrigerant to the coils, thermostats associated with each of the coils, a double pole switch controlled by each of said thermostats whereby when the switch is in the on position said magnetic valves will be in position to open and when in the off position said valves will be closed, manually operable switches associated with said double pole switches for breaking the circuit through both poles of each switch, a pressure gauge having spaced contacts thereon in circuit withsaid manually operated switch, a connection between the cooling coils and said pressure gauge whereby the two circuits may be completed through the gauge at the limits of movement of the gauge, a relay associated with said pressure gauge whereby when the pressure has reached a predetermined amount the circuit through the double pole switches will be closed and the magnetic shut-off valves will be open, the motor being permitted to drive the compressor to force refrigerant to the coils, substantially as set forth.

3. The combination in a refrigerating system including a compressor and a condenser,

refrigerating coils for receiving refrigerant from the compressor, a motor for operating the compressor, magnetically or motor controlled valves for controlling the supply of refrigerant to the coils, thermostats associated with each of the coils in each cooling compartment, a double pole switch controlled by each of said thermostats whereby when the switch is in the on position said magnetic valves will be in pos tion to open and when in the off position said valves will be closed, manually operable switches associated with said double pole switches for breaking the circuit through each switch, a pressure gauge vhaving spaced contacts thereon in circuit with a relay, a gas line connection between the cooling coils and said pressure gauge whereby the pressure may be transmitted to the gauge so that two circuits, one at a time, may be completed through the gauge at certain limits of movement of the gauge, said relay associated with said pressure gauge whereby when the pres sure has reached a" predetermined low amount, they gauge acts to operate said relay and to complete the circuit to the magnetically or motor operated shut oif valves so that said shut off valves will be in a position to be opened, and when the pressure has reached a predetermined high valve, the circult to the shut off valves will be opened and said valves closed, the motor being permitted to drive the compressor and force refrigerant to the coils through one of the poles of the thermostat, substantially as set torth.

4. A refrigerating system comprising a compressor, condenser and a plurality of compartments having refrigerating coils therein, a magnetic shut-off valve for controlling the supply of refrigerant to each compartment, a double pole thermostatically controlled single circuit mercury tube switch associated with each compartment the upper tube of said switch being adapted to control the starting and stopping of the compressor motor and the lower tube being adapted to control its associated magnetic shut-off valve said switches being connected in parallel whereby the compressor motor will operate so long as the circuit is closed through its respective switch, and means operable by the pressure within'the coils for controllingthe o ening and closing of the shut-off valve, su stantially as set forth.

5. A refrigerating system comprising a compressor, condenser and a plurality of both poles of i compartments having refrigerating coils therein, magnetic shut-oil valves for controlling the admission of refrigerant to said compartments, a double pole thermostatically controlled single circuit mercury tube switch associated with each compartment the upper tube of said switch being adapted to control the starting and stopping of the compressor motor and the lower tube being adapted to control the magnetic shut-0d valve said switches being connected in parallel whereby the compressor motor will operate so long as the circuit is closed through its respective switch, means operable by the pressure within the coils for operating said shut-oil valves, and means permitting said motor and compressor to operate while said magnetic valves are in closed position, substantially as set forth.

6. A refrigerating system comprising a compressor, condenser and a plurality of compartments having refrigerating coils therein, magnetic shut-off valves for controlling the admission of refrigerant to said compartments, a double pole thermostatically controlled singlecircuit mercury tube switch associated. with each'compartment the upper tube of said switch being adapted to control the starting and stopping of the compressor motor and the lower tube 'being adapted to control the magnetic shut-off valve said switches being connected in parallel whereby the compressor motor will op-' crate so long as the circuit is closed through" its respective switch, means operable by the pressure within the coils for operating the shut-oit valves, and means permitting said motor and compressor to operate, while said valves ,are in the closed position, substantially as set forth.

7. A refrigerating system comprising a compressor, condenser and a plurality of compartments having refrigerating coils therein, a magnetic shut-off valve for controlling the supply of refrigerant to each compartment, :1. double ole thermostatically controlled single circuit'mercury tube switch associated with each compartment the upper tube of said switch being adapted to control the starting and storming of the compressor motor and the lower tube being adapted to control the magnetic shut-off valve said switches being connected in parallel whereby the compressor motor will operate so long as the circuit is closed through its respective switch, means operable by the pressurevvithin the coils for operating said shut off valves, and means for causing one or more of the refrigerant compartments to control the o eration of the motor, substantially as set forth.

8. A refrigerating system comprislng a compressor, condenser and a plurality of compartments having refrigeratin coils therein, a magnetic shut-off valve or controlling the supply of refrigerant to each compartment, a double pole thermostatically controlled single circuit mercury tube switch associated with each compartment the one tube of said switch being adapted to control the starting and stopping of the compressor motor and the other tube being adapted to control the ma netic or motor operated shut-off valve, said switches being connected in. parallel whereby the compressor motor will operate so long as the circuit is closed through its respective switch, means operable by the pressure within the coils for controlling the operation of the shut-off valves, and means for causing one or more of the refrigerant compartments to control the operation of the motor,substantially as set forth.

In witness whereof, I have hereunto set my hand at VVaynesboro, Pennsylvania, this 8th day of May, -A. 1)., nineteen hundred and twenty-six;

FRANK R. ZUMBRO.

Images