US2236058A - Refrigerating apparatus - Google Patents

Description

patented Mar. 25, 1941 UNITED STATES REFRIGEBATING APPARATUS Charles F. llenney, Dayton, hio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application 0ctober 9, 1935, Serial No. 44,249

Claims.

This invention relates torefrigeration,

It is among the objects of this' invention to provide a method of, and apparatus for, conditioning air, in which the various functions of the psychrometric conditions of air are properly maintained. f

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

In the drawing: Fig. 1 is a diagrammatic representation of an apparatus embodying features of my invention; 'd Fig. 2 is a wiring diagram applicable to the apparatus shown in Fig. i;

Fig. 3 is a wiring diagram of a manual control for the air blower; and i Fig. 4 is la modied wiring diagram applicable to the apparatus shown in Fig. 1.

In practicing my invention, refrigerant is evaporated in an evaporating zone and the gaseous refrigerant is preferably withdrawn therefrom -at a substantially constant volumetric rate. Air is forced in thermal exchange with the evaporating refrigerant in the evaporating zone, and the velocity of the air is changed to compensate for varying psychrometric conditions in the air.

An apparatus suitable for accomplishing this is shown in Fig. 1`. In this apparatus, an evaporating zone is maintained in the .evaporator Il.

Evaporated refrigerant is withdrawn from this evaporator at a substantially constant volumetric rate by means of a compressor Il driven by a constant speed electric motor I2, The compressed refrigerant is discharged from the compresser into the condenser Il, from whence the liquefied refrigerant flows through the pipe I4 to the evaporator Il. In passing to the evap- 40 orator I0, the refrigerant flows through an automatic expansion valve I5, which is of the type which automatically discharges liquid refrigerant to the evaporator when the pressure thereof is reduced belowa predetermined limit. This valve is also automatically throttled by a thermostatic bulb I 6, placed at the outlet of the evaporator so that when the refrigerating effect reaches the bulb I6, the flow of liquid refrigerant is automatically throttled at the valve I5.

The condenser I3 may be of any usual construction. For example, as diagrammatically shown, it may be a cylindrical casing in which a water coil Il is placed. Flow of water through 55 the coil Il may be controlled by a pressure resufficiently low so that the highest speed of air is' sponsive valve I la, responsive to the head pressure of lthe compressor.

Air is forced in thermal exchange with the evaporating zone or evaporator l0 by any suitable means, such as a fan or blower Il. This 5 blower is driven by suitable means capable of varying the speed thereof. Thus it may be 'driven by an electric motor I9 of the variable speed type. Air from the room 2h, or from outside the room 20, or both, may enter through the in- 10 lets 2| and 22, and flows past the evaporator Il and is discharged through the outlet 23 into the room 20.

The operations ofthe compressor il and the blower Il are controlled in accordance with functions of the psychrometric conditions of air, A way of accomplishing this is diagrammatically indicated in Fig. 2. Preferably the operation of the compressor i I is controlled so that it operates whenever the temperature conditions or the relative humidity conditions in the room require it. The blower I8 is operated at varying speeds as the relative humidity of the air in the room A2l Vvaries when the temperature in the room is not necessarily required.

The thermostat 2l, which may be either a dry bulb or a wet bulb thermostat, is placed in a position to be responsive to temperature conditions inside the room 2li, .it being understood, however, that it may be placed outside of the room if desired. Whenever the temperature in the room 2| is above a predetermined limit, such as to require the highest blower speed, the contact 25 closes upon the contact 26. This energiaes the solenoid 2l and opens the contacts 28. As will be hereinafter more apparent, the opening of the contacts 28 prevents the blower motor i9 from running at a slow speed. In this manner the ilow of air past the evaporator zone lll is at its ,maximum whenever the temperature conditions -in the room 20 are relatively high and above a predetermined limit. Whenvthe temperature falls to. or below, another predetermined limit, the contact 25 closes upon the contact 29 and opens contact 26.v This energizes the solenoid l0 and closes the contacts 3i, thus placing the solenoid 32 under the control of the humidostat contact 34. At the same time the contacts 39 are opened and contacts 28 are closed, thus making itpos- 50 sible for the humidostat to vary the blower motor speed.

The relative humidity in the room 20 (or outside the room 20, depending on the position of the humidostat H inside or outside the room) 55 determines the speed of the blower IB and the operation of the compressor II when the temperature conditions are below the last named predetermined minimum. If the relative humidity conditionsare below a predetermined degree, the contact 34, under the control of humidostat H, closes upon the contact 35, and when the relative humidity conditions are above a predetermined degree the contact 34 closes upon the contact 36. Thus when the relative humidity conditions are relatively low so that the contacts 34 and 35 are closed, and when at the same time the temperature is relatively low so that contacts 25l and 29 are closed, the compressor motor I2 is stopped since refrigeration is not required. This is accomplished because current flows to the solenoid 32 which in turn opens the contacts 50. This opens the electric circuit to the motor I2 and stops the compressor. When the relative humidity rises, but the temperature remains sufficiently low to keep the contacts 25 and 29 closed, then the contacts 34, 35 are opened and the contacts 34, 36 closed. The opening of the contacts 34, 35 de-energizes the solenoid 32, thus closing the contacts 50 and causing the compressor motor I2 to operate. The closing of the contacts 34, 36 causes current to pass through the contacts 28, through the resistance 31 and the main winding 38 of the motor I9. This causes the motor I9 to operate at its slow speed thus causing air to be forced over the zone I0 at a relatively slow speed.

When the relative humidity is relatively high, so that the contacts 34, 36 are closed, and if the temperature is also high at this time, so that the contacts 25, 26 are closed, then the solenoid 21 is energized and closes the contacts 39. This shunts the resistance 31 and places the main winding 38 across the lines 40, and causes the blower motor I9 to operate at full speed.

The motor I9 may be of any suitable self-starting type such as an induction-repulsion start motor or a shaded pole motor. The actions of the contacts 25 and 34 are preferably snap acting.

The change from high speed to low speed of the motor I9 may be manually controlled, if desired. This may be accomplished as indicated in Fig. 3. One of the power lines 40a may be connected to the central post 4I of the manual switch 42. The post AI may be connected to one side of the main winding 43 of a motor corresponding to motor I9. The post -2 may be con..

nected to an intermediate point of the resistance 44 while the point 3'is connected to-place the entire resistance14 in the circuit. `The manual switch 42 is of the character `which can be rotated only clockwise and is so arranged that the contact arm 45 snaps from the positions I, 2, 3, 4 and back to I only in a clockwise direction. The position 4 is an open position so that the motor I9 is stopped at this position. When the contact is moved to position I, current flows through the main winding 43. At this time a starting control, such as a centrifugal control, maintains the contact 46 against the contact 41. This places the starting winding 48 also across the lines and brings the motor up to speed. When sufficient speed has been attained the contact 46 snaps down to the contact 49. If the arm 4I remains in position I, the motor continues to operate at full speed. If the contact 45 is snapped to position 2, then a portion of the resistance 44 is placed in series with the winding 43 and the motor is operated at a slower speed. If the contact 45 is then snapped to the position 3 the entire resistance 44 is placed in series with the winding 43 and the motor I9 operates at still a slower speed. Thus the flow of air over the evaporator III may be manually controlled by means of the switch 42 to produce any number of different air velocities over the evaporating Zone.

By the arrangement shown in the drawing, refrigerant is withdrawn from the evaporating zone I0 at a substantially constant'volumetric rate by means of the constant speed compressor II. Air is forced over the evaporator I 0 by means of the fan I3, and the velocity of the air is regulated in accordance with air conditions either automatically by the humidostat H or manually by means of the switch 42. When air flows over the evaporator at the slower rate, a larger amount of moisture is removed from the air in comparison to the reduction of the dry bulb temperature. This produces a relatively large amount of dehumidification in comparison with the reduction in sensible temperature.

It may also be desirable to reduce the speed of the compressor when the temperature is low and the relative humidity is high. This may be accomplished as shown in Fig. 4 which shows how the wiring of Fig. 2 maybe modified. The switch bar 60 under the control of solenoid 21 may be provided with vcontact 6I which bridges the contact 62 in the compressor motor line. When the temperature is low and the bar 60 is down, then the resistance 63 is placed in series with the motor I2 and causes the compressor to operate at reduced speed. This causes the air velocity and the refrigerating capacity to be reduced simultaneously when the temperature is low and the relative humidity is high. The reduced air velocity and reduced refrigeration capacity are so calibrated that moisture is removed from the air, but the reduction in sensible temperature is small compared with the heat infiltration into the room and the addition of heat by its occupants.

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. An air conditioning apparatus comprising, a compressor, condenser and evaporator in refrigerant flow relationship, a blower for blowing air over said evaporator, means for automatically varying'the operation of said blower in accordance with relative humidity conditions,l and means for operating said compressor at either a high speed, low speed or for stopping said compressor in accordance with a function of the psychrometric conditions of air.

2. 'Ihe method of conditioning air which comprises withdrawing evaporated refrigerant from an evaporating zone into a liquefying zone, circulating air to be conditioned in thermal exchange with said evaporating zone, withdrawing said refrigerant slowly and circulating said air slowly when the humidity is high and the temperature is low, withdrawing said refrigerant rapidly and circulating said air slowly when both the humidity and temperature are high, and withdrawing said refrigerant rapidly and circulating said air rapidly when the humidity is low and the temperature is high.

3. The method of conditioning air which comprises withdrawing evaporated refrigerant from an evaporating zone into a liquefying zone, circulating air -to be conditioned in thermal exchange with said evaporating zone, withdrawing said refrigerant slowly and circulating said air slowly when the humidity is high and the temperature is low, withdrawing said refrigerant rapidly and circulating said air slowly when both f the humidity and temperature are high, withdrawing said refrigerantl rapidly and circulating said air rapidly when the humidity is low and the temperature is high, and stopping both the flow of refrigerant and the circulation of air when both the temperature and humidity are.

the humidity is high and the temperature is low,

means whereby said compressor operates rapidly and said blower operates slowly when the humidity and the temperature are both high, and means whereby said compressor and said blower both operate rapidly `when the humidity is low and the temperature is high.

5. Air conditioning apparatus comprising, a compressor, a condenser and angevaporaztor in refrigerant flow relationship, a blower for blowing air .over said evaporator, means responsive to changes in the moisture content of the air for automatically varying the operation of said blower, and means for operating said compressor at either a high speed, low speed or for stopping said compressor in response to changes in at least one function of the psychrometric condition of the air.

CHARLES F. HENNEY.`

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