US2203497A - Refrigeration - Google Patents

Description

June 4, 9 .w. H. KlTTO ET AL REFRIGERATION Filed Dec. 23, 1957 2 Sheefs-Sheet 1 Patented June 4, 1940 UNITED STATES REFRIGERATION William H. Kitto and Arnold D. Siedle, Canton, Ohio, assignors to The Hoover Company, North Canton, Ohio, a corporation of Ohio Application December 23, 1937, Serial No. 181,281

12 Claims.

This invention relates to refrigerating apparatus and more particularly to control mechanism for such apparatus. In absorption refrigcrating apparatus as previously constructed the control mechanism has been located in the lower part of the cabinet adjacent the boiler thereby necessitating an elongated flexible connection between the manual control means and the regulating device for the control mechanism. This arrangement resulted in a diflicult assembly due to the necessity for leading a flexible control cable from a point adjacent the evaporator to the boiler without sharp bends. Also the flexible cable encased in a coiled wire housing introduced a large frictional load on the control adjusting mechanism with the result that the manual regulating knob-usually mounted adjacent the evaporator-was diflicult to operate.

A flexible cable connection between the manual adjusting knob and the thermostatic control mechanism introduced a very troublesome adjusting problem due to the fact that slight elongation of the cables, slippage on the pulleys,

or slipping of the cable housing would destroy the calibration of the sensitive temperature range adjusting mechanism for the thermostatic bellows.

If the gas valve and thermostatic controlling mechanism of an absorption refrigerating system is mounted on or adjacent the boiler it is apt to be injured by the excessive temperature conditions prevailin at these points. The delicate bellows and springs of the thermal control and the accurately formed gas valve ports may warp orlose their temper if subjected to high temperatures. Also the bellows is filled with a fluid which expands and contracts with small temperature changes. If the bellows is positioned in a high temperature zone it will not respond accurately to temperature changes in the cooling unit; this was further complicated by the fact that the capillary tube connecting the bellows and the bulb mounted on the evaporator had to be of extreme length and well insulated. However, even with the greatest care, the calibration of the control mechanism may be destroyed by heating, bending or elongation of the capillary tube.

Accordingly, it is an object of this invention to arrange a refrigerator control mechanism in a position not subjected to temperature extremes, permitting a direct positive mechanical connection between the adjusting knob and the temperature range adjusting mechanism, and permitting a short capillary connection between the bellows in the control mechanism and the thermostatic control bulb in the food cmpartment.

It is a further object of this invention to provide a control mechanism which is simply mount-' ed and is positioned to be serviced with a minimum of difliculty.

It is another object of this invention to mount a control mechanism on a refrigerating appa: ratus in such fashion that the entire system including the control may be tested as a unit and may then be mounted in a cabinet as a unit.

It is a further object of this invention to provide a control mechanism having a manual adjusting knob which may be operated witha minimum of effort on the part of the operator.

It is a further object of this invention to provide a control mechanism adapted simultaneously to control a gas valve and an electric switch which regulate the supply of energy to an absorption refrigerating system.

It is a further object of this invention to combine a novel defrosting mechanism with a novel refrigerating control mechanism. 25

Other objects of the invention reside in various arrangements and construction of parts which will be apparent as the description proceeds when taken in connection with the accompanying drawings, in which:

Figure 1 is a partial sectional view of a refrigerating apparatus embodying my invention.

Figure 2 is a horizontal sectional view taken along the line 2-2 of Figure 1 and looking in the direction of the arrows.

Figure 3 is a partial sectional view on an enlarged scale of my control mechanism.

Referring now to the drawings and first to Figures 1 and 2 thereof, it will be seen that I have disclosed a continuous three-fluid absorp- 40 tion refrigerating system of the type utilizing a gas burner to generate refrigerant and a motordriven fan to circulate an inert gas. The refrigerating system comprises a boiler B, an analyzer A, a rectifier R, a condenser C, an evaporator E, a gas heat exchanger H, an absorber D, and a circulating fan F driven by a motor M. These elements are suitably connected in circuit to form a complete refrigerating system.

Heat is applied to the boiler B from a suitable gas burner G of conventional design and provided with suitable safety-cut-off means. The boiler B contains a solution of refrigerant in an absorbent, preferably ammoniain Water, which liberates ammonia vapor when subjected to heat.

upwardly through the analyzer A in counterflow to strong absorption liquid supplied in a manner to be described hereinafter. The refrigerant vapor exits from the analyzer A through a conduit II which is connected. to the condenser C and includes arectifier R. Entrained water vapor is condensed in the rectifier R and is returned to the analyzer A. The condenser C is preferably a tubular finned air-cooled type. The refrigerant vapor is liquefied in the condenser C and is dis-- charged through a conduit i2 into a finned box cooling conduit l3 forming the upper part of the evaporator E. The liquid refrigerant flows downwardly through the evaporator by gravity counter to a stream of an inert pressure equalizing medium, such as hydrogen or nitrogen, which is supplied from the gas heat exchanger H through a conduit l4. A suitable drain for the evaporator is indicated at l4.

The liquid refrigerant vaporizes into the pressure equalizing medium in the evaporator to produce refrigeration and the resulting mixture of refrigerant vapor and pressure equalizing medium exits from the evaporator through the box cooling conduit l3 and the conduit l5 into the gas heat exchanger H.

The rich mixture is conveyed from the gas heat exchanger H through a conduit It to the lower end of the absorber D which is preferably of the finned tubular air cooled type. The vapor-gas mixture passes upwardly through the absorber D in counterflow to weak absorption liquid flowing downwardly by gravity whereby the refrigerant vapor is absorbed in the liquid and the pressure equalizing medium exits from the absorber D through the conduit ll into the suction inlet of the circulating fan E which is driven by a motor M, preferably of the hermetically sealed type. The gas is discharged under pressure through the conduit l8 into the gas heat exchanger. The weak gas returns to the evaporator E from the gas heat exchanger H through the conduit l4 previously described.

Weak liquor formed in the boiler B as a result of generation of refrigerant vapor exits therefrom through the conduit 9, liquid heat exchanger 20, and conduit 2| which communicates with the upper end of the absorber D at the point at which the conduit l'l connects with the absorber D. The strong liquor formed in the absorber D exits from the lower end thereof through a conduit 22, the liquid heat exchanger 20 and a conduit 23 which discharges into the analyzer A. A conduit 24 connects the gas discharge conduit l8 with the weak liquor conduit 2| at a point below the liquid level in the boiler-analyzer system whereby the weak liquor is elevated into the upper end of the absorber'by gas-lift action.

The refrigerating apparatus just described is housed within a suitable insulated cabinet 38 which is provided with a suitable door 3|. The evaporator E is positioned in the top central portion of a food compartment 32. The refrigerating apparatus with the exception of the evaporator E and the gas heat exchanger H is housed within a space 33 extending along the bottom of the cabinet 80 beneath the compartment 32 and vertically along the rear thereof.

The vertical portion of the space 33 forms an air-cooling flue for various heat rejecting portions of the system. Cooling air enters the space 33 through suitable openings in the bottom of the cabinet 30 and also if desired through suitable louvers in the-rear panel 34 of the cabi- Ammonia vapor generated in the boiler B passes net. The cooling air flows upwardly over the aircooled absorber D, the rectifier R, and the condenser C and exits through suitable openings formed in the top of the cabinet 30.

The entire refrigerating apparatus is mounted upon a suitable framework, not shown, and is designed to be inserted as a unit into the cabinet 30 after which the rear plate 34 is mounted on the apparatus. A suitable window 40 is formed in the rear wall of the cabinet 30 and is designed to be closed by an insulating block 4| which encloses the upper part of the gas heat exchanger and the connections to the evaporator and is carried by the refrigerating apparatus. The insulating block 4| and the insulated rear wall of the cabinet 30 are formed with a vertically extending channel 41 which receives the gas heat exchanger H. The open face of the channel 41 is closed by an insulating block 42 which is shaped to embrace the gas heat exchanger and.

to seal the channel.

The control mechanism 50 for the gas burner G and the motor M is rigidly attached to the block 4| in any suitable manner. The control mechanism is adjusted by means of a manually actuated knob 5| rotatably mounted in any suitable manner in a control panel 52 which is attached to the casing of the evaporator E and extends thereabove completely con'cealing the box-cooling evaporator section IS. A control shaft 53 extends rearwardly from the knob 5| above the finned conduit l3, through the insulating block 4|, and carries on the outer end thereof a beveled gear 54 which meshes with a beveled gear 54' rotatably mounted on the control mechanism 50.

The control mechanism carries thereon a valve 55 which controls the supply of gas to the burner G. Gas is led into-the valve 55 from a conduit 48 and is conducted from the valve to the burner G by a conduit 49.

Products of combustion from the burner G pass through the boiler B and are conducted therefrom by a conduit into a distributing flue 46. The flue '46 is flared upwardly from its junction with the conduit 45 and terminates in an elongated discharge mouth adjacent the top portion of the cabinet 30. Flue 4c is positioned laterally of the control mechanism to prevent hot products from impinging on the control mechanism and the gas valve.

Referring now to Figure 3, it will be seen that our control mechanism comprises the casing 50 which rigidly carries on one end thereof the gas valve which is of a conventional on and oiP type and is provided with the usual pilot by-pass, not shown. The gas valve 55 is which extends into the housing 50 and is suitably guided therein for reciprocatory motion.

A small coil spring 44 positioned within the housing 50 urges the valve 55 to the closed position.

A suitable bellows 51 is slidably mounted in a guide ring 58 which is rigidly mounted in the housing 50 in any suitable manner The bellows 51 is provided with a hollow extension 59 which is slidably mounted in a bushing 60 threaded into the wall of the casing 50. '-A stifl spring BI is interposed between the bushing 60 and a plate 62 which abuts the end of the bellows 51 and the guide ring 58. The hollow conduit 59 communicates through a capillary tube 63 with a bulb element 54 which is mounted on any suitable the housing 50. A suitable collar 66' prevents the shaft 68 from shifting laterally with respect to the housing 50. The end of the shaft 68 within the housing 50 is threaded and receives an adjusting nut 69 which is provided with an extension engaging a guide rib I6 formed integrally with the housing 50 to prevent rotation of the nut 69 with the shaft 68. A suitable spring II is interposed between the nut 69 and the actuating arm 66 whereby rotation of the shaft 66 adjusts the resistance against which the bellows 51 must expand.

The free end of the actuating arm 66 is provided with a conical member I2 which bears in a depression in a spring retaining cup I3 receiving one end of a snap spring I4. The opposite end of the spring 14 is received within aspringretaining cup I5 which has a depressed portion receiving aconical element I6 carried by a follower arm The follower arm I1 is carried by a U-shaped supporting bracket I8, only half of which is shown, pivotally mounted at I9 to fixed support 80. The support 86 also carries an adjustable limit stop 86' for the arm 66. It will be seen that the snap spring I4 is positioned between the arms of the U-shaped bracket I8. The arm 11 is positioned to engage the valve actuating shaft 56 at one extreme limit of its movement and to engage one element 8| of a make and break switch 82 in the other extreme limit of its movement.

The snap mechanism is shown in position to open the valve 55 and to allow the switch 82 to close. In the opposite position of the snap mechanism the spring 44 closes the valve and the follower arm 11 engages the element 6| to open the Switch 82.

The switch 82 is connected to a line wire 63 and to a wire 84 which is connected to the circulating motor M, v

The actuating arm 66 is provided with a latch member 85 which is adapted to engage a latchkeeper member 86 formed on the end of a defrosting lock-out arm 81 which is pivotally mounted in housing 50 at. 88. A small torsion spring 89 urges the look-out arm 81 in a counterclockwise direction as viewed in Figure 3. Counter-clockwise rotation of the arm 81 is prevented by engagement with the plate 62 previously described. The end of the arm 81 engaging the plate 62 is formed with a cam surface 9| which will cause clockwise rotation. of the arm 81 when the plate 62 is shifted to the leftas viewed in Figure 3.

In operation, the bellows 51 expands and contracts in response to temperature changes in the evaporator E and cycles the switch 82 and gas valve 55 in a manner to maintain the evaporator within predetermined "temperature limits.

The temperature limits in the evaporator are determined by the compression of the spring H which is determined by the setting of the knob 5| through the agency of the gears 54 and 54' and the adjusting shaft 53.

Defrostlng is accomplished by turning the knob 5| to the defrosting position, suitably marked on the panel 52, and then returning the knob to any normal control point, also suitably marked on the panel 52. Movement of the knob 5| to the defrosting position advances the nut 69 to such an extent that the spring II will rock the arm 66 in a counter-clockwise direction, as viewed in Figure 3, a distance sufficient to cause the latch member 85 to engage behind the latch-keeper 86. Under these conditions the bellows 51 is locked against movement in a direction to swing the arm 66 in a clockwise direction, as viewed in Figure 3, to open the valve 55 and to close the switch 82, and the evaporator temperature rapidly increases to a value high enough to melt frost therefrom.

As the evaporator warms up the bellows 5'! expands to the left, as viewed in Figure 3, and compresses the stiff spring 6|. The plate 62 shifts to the left with the slidably mounted end of the bellows and releases the engagement between the members 85 and 86 by coaction with the cam surface 9 I when the evaporator has defrosted whereupon the bellows is released and the machine returns to normal operation.

The valve is positioned to be swept by the warm air flowing upwardly in the space between the panel 36 and the rear wall of the storage compartment due to the heat rejected by the absorber, condenser, and rectifier. The boiler flue system also induces a warm air flow upwardly through the cooling flue. However, the valve is not subjected to hot products of combustion as these are discharged laterally of and above the casing 56. The warm air stream prevents condensation of water vapor in the gas valve but is not sufficiently hot to injure the valve and control mechanism or to impair the calibration of the control mechanism.

- The control mechanism is adjusted from the control knob by a direct and positive connection whereby there is no possibility of loss of adjustment for the control mechanism by reason of slipping or elongating cables. Also the operator need only supply sufflcient force to the knob 5| to advance or retract the nut 69 and he need not overcome the frictional resistance inherent in a long encased cable which follows an irregular path.

While we have illustrated and described only a single embodiment of our invention, it is to be understood that it is capable of expression in other forms and constructional variations without departing from the spirit of the invention and the scope of the appended claims.

We claim:

1. Refrigerating apparatus comprising a storage compartment, a window formed in the rear wall of said compartment, a cold-producing mechanism including a cooling unit adapted to be inserted into said compartment through said window, a closure member for said window carried by said cold-producing. mechanism rearwardly of said cooling unit, and control mechanism for said cold-producing mechanism mounted on said closure member. 7

2. Absorption refrigerating apparatus comprising a boiler, a condenser, an evaporator, an absorber, means interconnecting said elements to form an absorption refrigerating system including a pressure equalizing medium circuit between said absorber and said evaporator, power-driven means for circulating a pressure equalizing medium through said pressure equalizing medium circuit, means for applying heat to said boiler,

1 control means for said apparatus mounted at the level of said evaporator, said control means introl said power-driven circulating means and said means-for applying heat to said boiler.

3. Absorption refrigerating apparatus comprising a cooling compartment, a cooling duct extending vertically in the rear of said compartment, a mechanism chamber beneath said compartment, a boiler in said chamber, an absorber in said chamber and beneath said cooling duct, a condenser in said duct, a cooling unitin said compartment, means connecting said boiler, absorber, condenser, and cooling unit in circuit to form a refrigerating system, means for applying heat to said boiler, means for conveying products of combustion from said boiler to an area. adjacent the top of said cooling duct, and control means mounted in said duct at the level of the cooling unit and positioned remotely from said combustion products discharge area.

4. Absorption refrigerating apparatus of the type involving a boiler and a cooling unit within a storage compartment said apparatus including means to heat said boiler, control means for said boiler heating means positioned at the level of said cooling unit, and means shielding said control means from temperature conditions prevailing at said boiler and said cooling unit.

5. Refrigerating apparatus comprising an insulated storage compartment, an evaporator.

mounted in said compartment, a finned boxcooling evaporator conduit mounted on the top wall of said evaporator, an upstanding front panel on'said evaporator arranged to hide said finned box-coiling conduit, control mechanism for said apparatus mounted on the rear wall of said cabinet at the level of said box-cooling conduit, an adjusting element for said control mechanism mounted on said panel, and a direct mechanical connection extending above said conduit between said adjusting element and said control mechanism.

6. Absorption refrigerating apparatus comprising an' insulated cabinet, a mechanism compartment associated with said cabinet, an evaporator mounted within said cabinet, means in said compartment for supplying refrigerant to said evaporator including a boiler, an absorber and a condenser, means for heating said boiler, control means for said boiler heating means mounted in said compartment-in position to be swept by warm air flowing therethrough from said absorber, and means shielding said control means from high temperature conditions existing in the vicinity of said boiler.

7. Absorption refrigerating apparatus comprising an insulated cabinet, a mechanism compartment associated with said cabinet, an evaporator mounted within said cabinet, means in said compartment for supplying refrigerant to said evaporator including a boiler, an absorber and a condenser, means for heating said boiler, control means for said boiler heating means mounted in said compartment in position to be tween said control means and said adjusting means.

8. Absorption refrigerating apparatus of the type including a boiler, a combustible fuel burner for heating the boiler and an insulated cabinet housing an evaporator comprising in combination aremovable insulated panel in said cabinet adjacent said evaporator, means. for controlling the supply of fuel to said boiler carried by said panel, means within said cabinet for adjusting said control means, means for shielding said control means from hot products of combustion discharged by said boiler heater, and means for flowing a warm air current over said control means.

9. Refrigerating apparatus comprising a cabinet, a cooling unit in said cabinet, control mechanism for said cooling unit mounted on the rear wall of said cabinet at the level of said cooling unit and offset therefrom, adjusting means for said control mechanism mounted adjacent said cooling unit, a drive shaft actuated by said adjusting means, and gearing connecting said drive shaft and said control mechanism.

10. Refrigerating apparatus comprising a cabinet, a cooling unit in said cabinet, control mechanism for said cooling unit mounted on the rear wall of said cabinet, said control means including an adjusting shaft extending generally parallel to the plane of the rear wall of said cabinet, adjusting means for said control mechanism mounted adjacent said evaporator, an adjusting shaft connected to said adjusting means and angular motion transmitting mechanism connecting said shafts.

11. Absorption refrigerating apparatus comprising an insulated cabinet, a mechanism compartment associated with said cabinet andincluding a portion extending along the rear wall thereof. an evaporating unit mounted in said cabinet, means for supplying refrigerant to said evaporating unit including a boiler and an aircooled heat rejecting-unit mounted in said compartment, said heat rejecting unit being arranged to discharge warmed air upwardly along the rear wall of said cabinet, control mechanism for said apparatus mounted in said compartment in position to be swept by the warm air discharged from said heat rejecting unit.

12. Absorption refrigerating apparatus comprising an insulated cabinet, a mechanism compartment associated with said cabinet and including a portion extending along the rear wall thereof, an evaporating unit mounted in said cabinet, means for supplying refrigerant to said evaporating unit including a boiler and an aircooled heat rejecting unit mounted in said compartment, said heat rejecting unit being arranged to discharge warmed air upwardly along the rear wall of said cabinet, a gas burner for heating said boiler. a gas valve for controlling said burner mounted in said compartment! above said heat rejecting element, means in said compartment for operating said gas valve in response to the thermal condition of said evaporating unit, and means for conducting waste products of combustion from said boiler to waste in a path

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