US2061599A

US2061599A - Refrigerating apparatus

Info

Publication number: US2061599A
Application number: US749055A
Authority: US
Inventors: Lloyd E Smith
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1934-10-19
Filing date: 1934-10-19
Publication date: 1936-11-24
Anticipated expiration: 1953-11-24

Description

Nov. 24, 1936. L. E. SMITH 2,051,599

' I REFRIGERATING APPARATUS Filed 001 19, 1934 Patented Nov. 24, 1936 UNITED STATES PATENT OFFICE,

REFRIGERATING APPARATUS Lloyd E. Smith, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, at corporation of Delaware ApplicationOctober 19, 1934, Serial No. 749,055

18 Claims.

' scription, reference being had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.

In the drawing:

The figure represents diagrammatically an apparatus embodying features 01 my invention.

In practicing my invention, a refrigerant liquefying unit I is connected with a plurality of evaporators ll, Na, and ill) in refrigerant-fiow relationship. The evaporators Ii, Ha, and lib are so constructed that they are likely to impose varying refrigeration loads on the refrigerant liquefying unit it.

The unit ill, which is operated by a motor l3, tends to have a relatively constant refrigerating capacity while the evaporators Ii, Ho and Nb may be connected to the unit it simultaneously or in time staggered relationship. This tends to create an unbalanced condition between the capacity of the unit ill and the evaporators ll, Ma

and lib. Controls are provided for balancing these capacities.

The refrigerant liquefying unit has a refriga erant low pressure side and a refrigerant high pressure side. Thus it may include a compressor I4 and a condenser M which is provided with a refrigerant receiver H5. The compressor M is provided with an evaporated refrigerant inlet H which forms part of the refrigerant low pressure side, and is connected by a discharge conduit ill with the condenser l5 which forms a part of the high pressure side.

The high pressure side is connected by a liquid refrigerant line is with the evaporators ll, Illa and lib which latter are provided with valve means at their inlets to control the flow of liquid refrigerant into the evaporators. The evaporators are also connected by an evaporated refrigerant line with the liquefying unit Ill thus forming the low pressure side of the system.

The valve means for the evaporators ll, Illa and lib may include automatic expansion valves 2i, 2 la and 2 lb which are of the character which automatically introduced refrigerant into the evaporators when the pressure therein is reduced below a predetermined limit. These expansion valves preferably are also provided with

thermostatic bulbs

23, 23a and 23b which automatically throttle the flow of liquid refrigerant into the evaporators in accordance with temperature conditions in a portion of the evaporators preferably located at the outlet of the evaporators. The construction and operation of these valves therefore is such that when the pressure in the evaporators is reduced below a predetermined limit they introduce liquid refrigerant into the evaporators unt'ifth'e refrigerating effect thereof reaches the bulbs 23, 23a and 2312, after which the valves throttle the fiow of refrigerant into the 'evap'orators to prevent the waste of refrigeration the

thermostats

27, 21a and 27b, placed in the

rooms

29, 29a and 2%, respectively, in which the evaporators are placed, open and shut the valves 25, a and 25b in accordance with air temperature conditions in the

rooms

29, 29a, and 29b;

The evaporators ll Ma and Nb may be of any suitable construction; but in the preferred form, they form parts of air conditioning for cooling equipment. Thus they may be placed in casings M, Ma. and MI) through which a circulation of air is forced by means of motor-driven fans 33,

-

valves

25, 25a and 25b. Under such conditions,

the amount of refrigeration required by the remaining evaporator or evaporators is materially reduced, while the capacity of the unit Ill tends to remain constant. Under such conditions the unit I0 would tend to reduce the refrigerant temperature in the remaining active evaporator or evaporators below the acceptable temperature. In the use of refrigerant evaporators for air conditioning, it is desirable to maintain the cooling surfaces of the evaporators above the freezing temperature of water, so that the cooling surfaces do not accumulate frost but merely condense the moisture from the air and permit it to flow away. When the capacity balance of the system is thrown off by the inactivity of one or more of the evaporators, the excess capacity of the unit l0 tends to reduce the temperature of the active evaporators to too low a temperature. This invention prevents this undesirable result.

Accordingly, means are provided for throttling the flow of refrigerant into the liquefying unit Ill when the pressure of the refrigerant from the evaporators falls below a predetermined or desirable limit and thus the temperature of the evaporators is prevented from falling below a selected limit, such as 32 F. This means takes .the form of an automatically actuated valve means 40 which is actuated by pressure responsive means or bellows 4| in accordance with the temperature-pressure conditions in the evaporated refrigerant line 20. As the pressure in line'20 falls to a temperature-pressure condition near the freezing point of water, the bellows 4| expands by the action of atmospheric pressure through the opening 42 on one side and the refrigerant pressure in the chamber 43. The expansion of the bellows 4| raises the valve rod 41 through the medium of the lever 44, which is pivoted at 45 and engages the pin 46 of the rod 41. When the valve 40 is thus raised, the flow of refrigerant in the low pressure side of the apparatus is throttled to prevent a drop in temperature of the active evaporators below the freezing point of water. The temperature-pressure limit at which the valve 40 closes in response to the action of the bellows 4| is chosen to be below the pressure-temperature conditions at which the valves 2|, 2m and 2H) open. I

In the manufacture of refrigerating apparatus for air conditioning, it is quite usual to assemble the refrigerant liquefying unit as one piece of mechanism, and each of the evaporators H a and lb, etc., together with their casings, fans, valves, etc., as other pieces of mechanism. These factory assembled pieces of mechanism are shipped to the place where they are to be installed and there they are assembled for operation. It frequently happens that the Wrong number of evaporators are connected to a refrigerant liquefying unit. Sometimes the number actually installed is less than the proper amount for correct refrigeration balance and at other times the number of evaporators is more than the proper amount for correct balance. When less than the proper amount are installed, the valve 40 when actuated by the bellows 4| will prevent the unit I 0 from producing too low temperatures in the evaporators installed, and this invention is therefore applicable also to installations where the wrong number of evaporators are installed even when the evaporators are not independently out out.

In order to take care of the condition when too many evaporators are installed, means are provided to throttle the low pressure side when the pressure-temperature conditions in the evapora-- tors rise above a predetermined limit due to the presence of an excess number of evaporators. Either an additional valve, or the same valve 40 may be used for this purpose. If the valve 48 is used, a pressure responsive means in the form of bellows 48 is connected to the valve 40 through the medium of rod 41, pin 49 and lever 50 pivoted at 5|. When the pressure-temperature conditions in the line 28 and chamber 43 rise above a predetermined limit, the bellows 48 tends to col- 21a and 211) effective.

lapse because of the increased pressure differential between the chamber 43 and .the atmospheric pressure in bellows 48 entering through the opening 52. When the bellows 48 thus collapses the valve 48 rises andthrottles the flow of refrigerant to the unit l0 and thus prevents it from being overloaded.

It sometimes occurs that the refrigerant pressure on the high side becomes excessive, for instance when the flow of cooling medium to the condenser 5 is accidentally prevented. Means are provided for reducing the capacity of the unit I0 under these conditions and this may be accomplished by providing means for throttling the flow of refrigerant from the low pressure side to the unit l0 when these conditions occur. This may be accomplished either by an additional valve or by the same valve 40. Thus a rod 53 may be actuated by the bellows 54 which is Ct. rnected on one side by the pipe 55 with the high pressure side and with the atmosphere through the opening 56 on the other side. When the pressure becomes excessive on the high pressure side the rod 53 rises and throttles the valve 40.

It is to be understood that the bellows 4|, 48 and 54 may be each independently connected to an individual valve rather than all be connected to a single valve. Adjusting screws 51 and 58 may be provided to vary the tension of the springs 59 and 60 respectively so that the pressure conditions at which the bellows 4| and 48 operate may be adjusted. A small bellows 6| may be provided to prevent the escape of refrigerant through the opening 56, and spring means 62 may be provided to properly calibrate the action of the bellows 54.

If the refrigerant liquefying unit is manufactured as an entity at the factory it is often desirable to assemble the valve structure contained in the casing 63 with the refrigerant liquefying unit, thus insuring satisfactory operation of the unit l0 even if the same should be assembled with the wrong number of evaporators.

An automatic control may be provided for the unit Hi. This may take the form of a snap switch 64, operated by a bellows 65 in response to conditions of the apparatus, such as in response to the refrigerant pressure at the intake transmitted through the pipe 66 to the bellows 65 thus starting and stopping the unit ID as refrigerant conditions require.

Means are provided for permitting the fans 33, 33a and 33b to be operated when refrigeration is not desired and for insuring the operation of these fans when there is a refrigeration demand upon their respective evaporators. These means are preferably coordinated with the

thermostats

21, 21a and 21b and with the switch 64 to insure that the unit I 0 shall not operate for appreciable periods of time when all of the evaporators are rendered inactive but shall operate in response to pressure conditions when any one of the evaporators is rendered active.

Thus hand switches 69, 69a and 692) are provided which may cause the operation of the respective fans 33, 33a and 331) when air circulation is desired even when refrigeration is not desired. The closing of these switches energize the respective fan motors from source 39. Hand switches 10, 10a and 10b are also provided for rendering the refrigerant control thermostats 21, When any of the switches 70, 1011 or 10b are manually closed the corresponding thermostat is rendered capable of energizing its corresponding relay 61, 61a or 61b.

The energizing of any of the relays 61, 61a or 61b in turn closes its

corresponding switch

68, 58a or 68b which in turn energizes and opens its corresponding solenoid valve 25, 250. or 25b.

The above electrical controls therefore cause the unit I to maintain the refrigerant pressure in. suction line 20 between the lowest pressure limit for which bellows M is calibrated and the highest pressure limit for which switch 64 is calibrated. The low pressure limit of the switch 64 is made lower than the low pressure limit of the bellows II so that when the-bellows 4| throttles the valve 40 a certain amount the bellows 65 closes the switch 64. The unit It therefore maintains the suction line 20 in readiness to evaporate refrigerant in any one of the evaporators II, II a or llb whenever the corresponding

valve

25, 25a or 25b is opened. When any one or more of the switches 10, 'llla or 70b are closed then the corresponding thermostat 21, 2101. or 211) feeds refrigerant into its corresponding evaporator I I, Ila or lib in response'to the temperature in its corresponding room. This provides the necessary refrigeration for each room as it is required. At the same time the proper evaporator temperatures are maintained so that no deleterious frosting thereon occurs.

While 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. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a

frigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality of evaporators having refrigerant inlets connected to said high pressure side and refrigerant outlets connected to said low pressure side, throttling means on said low pressure side effective to throttle the flow of refrigerant into said li uefying unit when the pressure of the refrigerant from said evaporators falls below a predetermined limit and when the refrigerant pressure in said high pressure side rises above a predetermined limit.

3. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality of evaporators having refrigerant inlets connected to said high pressure side and refrigerant outlets connected to said low pressure side, throttling means on said low pressure side effective to throttle the flow of refrigerant into said liquefying unit when the pressure of the refrigerant from said evaporators rises above a predetermined limit and when the refrigerant pressure in saidhigh pressure side rises above a predetermined limit.

4. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality of evaporators having refrigerant inlets'connected to said high pressure side and refrigerant outlets rises above a predetermined limit.

5. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality of evaporators having refrigerant inlets connected to said high pressure side and refrigerant outlets connected to said low pressure side, expansion valves at said inlets having means for automatically introducing refrigerant into said evaporators when the pressure in said evaporators is reduced below a predetermined limit, throttling means on said low pressure side effective to throttle the flow of refrigerant into said liquefying unit when the pressure of the refrigerant from said evaporators falls below a predetermined limit and when it rises above a predetermined limit.

6. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality of evaporators having refrigerant inlets connected to said high pressure side and refrigerant outlets connected to said low pressure side, expansion valves at said inlets having means for automatically introducing refrigerant into said evaporators when the pressure in said evaporators is reduced below a predetermined limit, and having means for throttling the flow of refrigerant into said evaporators in accordance wi h temperature conditions in a portion of said evaporators, throttling means on said low pressure side effective to throttle the flow of refrigerant into said liquefying unit when the pressure of the refrigerant from said evaporators falls below a predetermined limit and when it rises above a predetermined limit.

7. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality of evaporators having refrigerant inlets connected to said high pressure side and refrigerant outlets connected to said low pressure side, valves at the inlets of said evaporators responsive to temperature conditions of air cooled by said evaporators,

throttling means on said low pressure side effec-- tive to throttle the flow of refrigerant into said liquefying unit when the pressure of the refrigerant from said evaporators falls below a predetermined limit and when it rises above a predetermined limit.

8. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality .of evaporators having refrigerant inlets connected to said high pressure side and refrigerant outlets connected to said low pressure side, electro-magnetic valves for said evaporators having means for electrical energization in accordance with conditions produced by said evaporators, throttling means on said low pressure side effective to throttle the flow of refrigerant into said liquefying unit when the pressure of the refrigerantfrom said evaporators falls below a predetermined limit and when it rises above a predetermined limit.

9. Refrigerating apparatus comprising a compressor, condenser and refrigerant evaporating means, an evaporated refrigerant line connecting said evaporating means and the intake of said compressor, a liquid refrigerant line-connecting said condenser and said evaporating means, throttling means in said evaporated refrigerant line effective to throttle the flow of refrigerant into gle valve in said evaporated refrigerant line effective to throttle the flow of refrigerant into said compressor when the refrigerant pressure in said evaporated refrigerant line falls below a predetermined limit and when the refrigerant pressure in said condenser rises above a predetermined limit.

11. Refrigerating apparatus comprising a compressor, condenser and refrigerant evaporating means, an evaporated refrigerant line connecting said evaporating means and the inlet of said compressor, a liquid refrigerant line connecting said condenser and said evaporating means,throttling means in said evaporated refrigerant line effective to throttle the flow of refrigerant into said compressor when the refrigerant pressure in said evaporated refrigerant line rises above a predetermined limit and when the refrigerant pressure in said condenser rises above a predetermined limit.

12. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality of evaporators having refrigerant inlets connected to said high pressure side and refrigerant outlets connected to said low pressure side, automatic expansion valves at said inlets, throttling means on said low pressure side effective to throttle the flow of refrigerant into said liquefying unit when the pressure of the refrigerant from said evaporators falls below a predetermined limit and when the refrigerant pressure in said high pressure side rises above a predetermined limit.

13. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality of evaporators having refrigerant inlets connected to said high pressure side and refrigerant outlets connected to said low pressure side, expansion valves at said inlets having means for automatically introducing refrigerant into said evaporators when the pressure in said evaporators is reduced below a predetermined limit, throttling means on said low pressure side effective to throttle the flow of refrigerant into said liquefying unit when the pressure of the refrigerant from said evaporators falls below a predetermined limit, and when the refrigerant pressure in said high pressure side rises above a predetermined limit.

14. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality of evaporators having refrigerant inlets connected to said high pressure side and refrigerant outlets connected to said low pressure side, expansion valves at said inlets having means for automatically introducing refrigerant into said evaporators when the pressure in said evaporators is reduced below a predetermined limit, and having means for throttling the flow of refrigerant into said evaporators in accordance with tem- V perature conditions in a portion of said evapor ators, throttling means on said low pressure side effective to throttle the flow of refrigerant into said liquefying unit when the pressure of the refrigerant from said evaporators falls below a predetermined limit and when the refrigerant pressure in said high pressure side rises above a predetermined limit.

15. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality of evaporators having refrigerant inlets connected to said high pressure side and refrigerant outlets connected to said low pressure side, valves at the inlets of said evaporators responsive to temperature conditions of air cooled by said evaporators, throttling means on said low pressure side effective to throttle the flow of refrigerant into said liquefying unit when the pressure of the refrigerant from said evaporators falls below a predetermined limit, and when the refrigerant pressure in said high pressure side rises above a predetermined limit.

16. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality of evaporators having refrigerant inlets connected to said high pressure side and refrigerant outlets connected to said low pressure side, electro-magnetic valves for said evaporators having means for electrical energization in accordance with conditions produced by said evaporators, throttling means on said low pressure side effective to throttle the flow of refrigerant into said liquefying unit when the pressure of the refrigerant from said evaporators falls below.a predetermined limit, and when the refrigerant pressure in said high pressure side rises above a predetermined limit.

17. Refrigerating apparatus comprising a refrigerant liquefying unit having a refrigerant low pressure side and a high pressure side, a plurality of evaporators having refrigerant inlets connected to said high pressure side and refrigerant outlets connected to said low pressure side, automatic expansion valves at said inlets, throttling means on said low pressure side effective to throttle the flow of refrigerant into said liquefying unit when the pressure of the refrigerant from said evaporators rises above a predetermined limit and when the refrigerant pressure in said high pressure side rises above a predetermined limit.

18. The method of operating a refrigeration system which comprises circulating a volatile refrigerant from a refrigerant liquefying zone through a liquid refrigerant conveying zone, through a plurality of evaporating zones in parallel into a common vapor-conveying zone and to the refrigerant liquefying zone for recirculation, maintaining the liquefying capacity of said liquefying zone sufficient for the demands of all of said evaporating zones, periodically stopping the flow of refrigerant through one or more of said evaporating zones, automatically throttling said vapor conveying zone to maintain the refrigerant pressure in said conveying zone adjacent said evaporating zones above the vapor pressure corresponding to 32 F., and automatically throttling said refrigerant conveying zone when its pressure rises above a predetermined limit.

LLOYD E. SMITH.