US2921446A

US2921446A - Refrigeration machine

Info

Publication number: US2921446A
Application number: US620129A
Authority: US
Inventors: Zulinke Adolph
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 1956-11-02
Filing date: 1956-11-02
Publication date: 1960-01-19
Anticipated expiration: 1977-01-19

Description

Jan. 19,1960 A. ZULINKE 2,921,446

REFRIGERATION MACHINE Filed Nov. 2, 1956 2 Sheets-Sheet 1 ADOLPH ZULINKE.

ATTORNEY.

FIG.

Jan. 19, 1960 A. ZULINKE 2,921,446

REFRIGERATION MACHINE Filed Nov 2, 1956 2 Sheets-Sheet 2 FIG. 4

F I 2 INVENTOR. ADOLPH ZULINKE.

ATTORNEY.

United States Patent REFRIGERATION MACHINE Adolph Zulinke, Syracuse, N.Y., assignor to Carrier Corporatlon, Syracuse, N .Y., a corporation of Delaware Application November 2, 1956, Serial No. 620,129

Claims. (Cl. 62-117) This invention relates generally to refrigeration machines employing centrifugal refrigeration systems. More specifically, this invention relates to centrifugal refrigeration systems employing economizer units.

In co-pending application Serial No. 566,190, filed February 17, 1956, in the name of C. M. Ashley and Adolph Zulinke, it is proposed to utilize vaporous refrigerant formed in the economizer to cool the motor controlling the centrifugal compressor. This is accomplished by connecting a portion of the economizer chamber with the motor compartment and then providing a line from the motorv compartment to the compressor. This compressor connection in this latter instance is made at a location between the inlet and the outlet of the compressor. As a part of the control for the flow of the economizer gas to the motor compartment a valve, responsive to a predetermined difference in pressure between the evaporator and the economizer, is placed in the line connecting the economizer and the motor compartment. I have discovered that if the valve is placed in the line connecting the motor compartment and the compressor compartment, certain important advantages may be obtained.

It is the chief object of this invention to provide an improved centrifugal refrigeration machine employing a refrigeration system wherein vaporous refrigerant formed in the economizer as the liquid refrigerant flows into the zone of reduced pressure is used to cool the motor.

Another object of this invention is the provision of an improved centrifugal refrigeration machine of the kind under consideration wherein the possibility of refrigerant foaming in the motor compartment with the consequent carry. over'of lubricant to the compressor and/or loss of oil pressure is reduced.

An additional object of this invention is the provision of an improved control mechanism for maintaining pressure in the economizer of an order suflicient to preclude the possibility of refrigerant flow from the evaporator to the economizer or the accumulation of refrigerant in the economizer due to failure to pass through the valve between the economizer and the evaporator under-the varying operational change to which the system is subjected.

A still further object of this invention involves the provision of an improved method of operating a centrifugal refrigeration machine.

Another object of this invention is the provision of a centrifugal refrigeration machine having an economizer, means for forwarding vaporous refrigerant formed in the economizer to the motor compartment of a motor compressor unit, means for providing a path for refrigerant flow from the motor compartment to the compressor and means located in said path for controlling refrigerant flow thereby regulating pressure in the economizer.

A still further object is the provision of an improved ice refrigerant flow member for assuring passage of gaseous refrigerant to the motor at low load.

Other objects and features of the'invention will suggest themselves upon a consideration of the ensuing specification and drawings in which:

Figure l is a schematic view of a refrigeration system equipped with a control of the type contemplated by this invention;

Figure 2 is a view in elevation of the control mechaanism of this invention;

Figure 3 is a view taken along lines 3-3 on Figure 2;

Figure 4 is an elevational view, partly in section, illustrating the valve between the condenser and the economizer; and 4 Figure 5 is a partial fragmentary View of a guide vane control mechanism used with the invention.

The refrigeration system to which this invention pertains is the same as proposed in the above-mentioned co-pending application. Centrifugal compressor 10 extracts gaseous refrigerant from the evaporator 11 through line 12, compresses it and forwards it to the condenser 13 where it is liquefied by cooling coil 14 in the usual manner. Liquid refrigerant flows from the condenser to a receiver 15 and into line 16 through valve 17. Line 16 is connected to the economizer 18 having a valve, under the control of a unit 19, similar to the

flow control unit

15 and 17, regulating passage of liquid refrigerant to line 20. From line 20 liquid and gaseous refrigerant enters the evaporator and the liquid is vaporized when in heat exchange relation with a medium such as Water flowing in a coil 21 in the evaporator. In the economizer a portion of the liquid refrigerant flowing from thecondenser or receiver flashes off or evaporates as it enters this zone of lower pressure. It will be appreciated that the coil 21 forms part of a chilled water circuit of the kind employed in conventional air conditioning systems.

In order to cool the motor 22, controlling the operation of the compressor, line 23 connects the upper part of the economizer with the housin 70 of the motor to form a path for the flash gas or vaporous refrigerant formed in the economizer. The gas emanating from the economizer flows into the motor housing and is directed by suitable baffling not shown here but of the type illustrated in the co-pending application into heat transfer relation with the motor. The refrigerant extracts heat from the motor through this action and flows through line 25 to the compressor at a location between the impellers or stages of compression.

For a reason to be more fully explained below, the refrigerant flow path defined by line. 23, the motor housing and the line 25, is provided with a control member 26, shown as a damper, operative in response to a predetermined pressure dilferential between the evaporator and the economizer. The damper is provided with'a linkage 27 responsive to a bellows 28 sensing economizer pressure on its outside surface and evaporator pressure on its inside surface. Opening 28a in line 25 permits economizer pressure to be exerted on the outside of the bellows. Line 29 connects the inside of the bellows with the evaporator.

The linkage 27 includes rod 27a secured to the damper 26. One end of rod 27a is journalled in line 25 and the other end projects beyond the opposite side of line 25. This latter end mounts bushing 27e, anchored to the outer surface of the line 25. The bushing in turn mounts annular stop member 27h, provided with an upstanding Wall portion 27m. Link 27b is pinned to the end of the rod 27a and mounts pin 27d pivotally. connected to rod 27c, which in turn is secured to bellows 28. Movement of link 27b is limited by the terminal ends of wall 27m. Appropriate sealing members 27g are employed to prevent escape of refrigerant from line 25. Housing 30a surrounds the linkage and bellows and is provided with an access cover 31a. Thus it will be obvious that movement imparted to the rod 270 will cause movement of the damper 26 within a predetermined range as established by the configuration of element 27h. Spring means 29a may be provided to maintain the damper closed when the pressure differential is reduced to a value such as to indicate possibility of a flow of refrigerant liquid up through the economizer and into the motor compartment due to an evaporator pressure in excess of the economizer pressure. It will be appreciated that movement of the damper 26 toward a closed position will cause pressure upstream from the damper to rise.

The pressure ditferential selected to control the damper is such that at shutdown, upon a tendency to equalize pressure throughout the system, the damper will be closed. This arrangement causes pressure to build up on the upstream side of the damper at start up, and eliminate the inconvenience attendant on subjecting the motor compartment to a pressure of a lower order which will cause flashing of any refrigerant that may be in the compartment.

In the above mentioned co-pending application certain arrangements operable under low load operation for permitting gaseous refrigerant to pass directly to the compressor from the condenser through the motor housing were suggested. One of the features of this invention involves the provision of an improved valve construction adapted to perform the same function. Referring more particularly to Figures 1 and 4 it will be observed that receiver is equipped with an outlet in communication with line .16. Surrounding the outlet is a casing 40 having a top wall 41, side walls 42 forming with the bottom of receiver 15, a chamber 43. Openings 44 in two of the opposed sidewalls permit flow of refrigerant from the receiver 15 to the line 16 through opening 16' in the bottom of the receiver.

Regulating flow of refrigerant through the openings 44 is a valve assembly 45 having

valve members

46 and 47 connected by a stem 48 so as to move in unison under the influence of a float 49 and linkage 50. The openings 44 are sized so that throughout the movement of the rod 50 a space between the outer periphery of

valves

46 and 47 and the perimeter of the openings exists. Mounted in the top wall of the casing 40 is a threaded bolt 51. The function of the bolt is to determine, in conjunction with the linkage 50, the limits of movement of rod 48. Arm 52 forming part of the linkage 50 is firmly connected at one end to the casing 40 and pivotally at its other end to link 53 which in turn is pivotally connected to one end of stem 48. The other end of stem 48 is pivotally connected to lever 54, pivotally connected to arm 55, which in turn is fixedly connected to casing 40.

Located centrally of lever 54 is an enlarged portion 62 having an opening 56 therethrough. The axis of the opening is inclined with respect to the axis of the bolt 51 over which it is mounted. Downward movement of float 57 connected to lever 54 and consequent movement to the right of stem 48 is limited by engagement of the bolt 51 by the enlarged portion of the lever 54 surrounding opening 56. Upward movement of the float 57 is limited by engagement between bolt 51 and the side of opening 56 opposite that shown in engagement with bolt 51 in Figure 4.

Thus when the system is operating at design conditions, flow of liquid refrigerant occurs through the openings 44. When a condition occurs such that the level of refrigerant drops in the receiver (as for example a reduction in the load on the evaporator as the temperature of the incoming chilled water drops and the suction vanes close in the conventional manner, or an abnormal rise in the condensing temperature), the

valves

46 and 47 move to close openings 44. However, there is a y 4 available, for passage of gaseous or uncondensed refrigerant, a space between the

valves

46 and 47 and the openings as indicated above. Thus there is provided a bypass for refrigerant gas under those conditions where surge of the compressor may be encountered, as well as a supply of gas for motor cooling.

Considering the operation of the system, at start up damper 26 is closed due to either equalized pressures in the machine or to the absence of a pressure differential between economizer and cooler of a magnitude to cause, in conjunction with the action of spring 29a, movement of the bellows 28 suflicient to open the damper. Gaseous refrigerant formed in the evaporator is withdrawn therefrom by the compressor, compressed and discharged to the condenser. Liquid refrigerant formed in the condenser flows to the receiver 15, chamber 43, line 16 to the economizer. Portions of the liquid refrigerant vaporize in the economizer in the usual manner, cooling the remaining liquid in the economizer which flows to the evaporator through flow control unit 19 and line 20. The gaseous refrigerant formed in the economizer flows through the line 23 to the motor housing and line 25, leaking slightly around closed damper 26.

As the pressure diflerential between the economizer and evaporator rises, damper 26 opens and permits substantially unrestricted flow of the gas warmed by contact with motor to the compressor.

During operation of the refrigeration machine, the demand for refrigeration fluctuates. The system or machine compensates for such variation in demand by balancing its capacity against the demand through the operation of automatic controls well-known in the art. For illustration, assume a drop in the demand for refrigeration such as occurs when the load on the machine is reduced.

The immediate effect of load reduction is a drop in the condensing temperature of the condenser. This reduction propagates itself into the evaporator through the compressor producing a decrease of evaporator and chilled water (coil 21) temperature. The reduction in the water temperature is detected by bulb which forms part of a thermal control for moving the guide vanes 78 toward a closed position, note Figure 5. Bellows 79 contracts, pulling a rod 81 having a toothed extremity acting as a rack' to a position effecting rotation of a pinion 82 keyed to the top portion of an extension on one of the guide vanes. Likewise secured to the guide vane is a pulley 83 which co operates with similar pulleys on the other guide vanes through cable 84 to insure movement of the vanes in unison.

The system then obtains operational equilibrium dependent in part upon the reduction in load on the system. Under these conditions the action of the guide vanes 78 results primarily in the reduction of the first stage pressure rise in the compressor which in turn reduces the over-all compressor lift to get the new lower condensing temperature. In view of this operational feature, well known in conventional machines of this type, at relatively low load, a substantial pressure drop across the guide vanes occurs as the vanes move toward a closed position. This pressure drop across thevanes causes a relatively low pressure at the inlet of the impeller of the first stage because the system control tends to maintain the pressure in the evaporator constant. Furthermore, since the net pressure rise across the vanes andthe first stage establishes the pressure differential between the economizer and the evaporator which in turn controls the transfer of liquid refrigerant from the economizer to the evaporator, it will be appreciated that when there is no pressure differential between the economizer and evaporator, the liquid refrigerant will accumulate in the economizer chamber and overflow through line 25 to the motor compartment. To prevent this from occuring, the damper and its associated control will operate to restrict passage of refrigerant through line 25.. As pointed out above the strength of the spring, resistance of the bellows, and values of the refrigerant pressures involved are selected so that the balance of forces acting on the bellows will actuate the damper in the desired direction to overcome any tendency of a pressure difference of a low magnitude or a pressure equalization to develop. The closing of the damper, of course, creates a pressure difference in the line 25 with pressure on the upstream or economizer side of the damper rising to the extent that a tendency for flow of liquid refrigerant in a direction reverse to that required is obviated and instead the liquid refrigerant in the economizer fiows to the evaporator.

Other characteristics of refrigeration system operation such as evaporator and economizer temperature may be used to control the operation of the damper without departing from the invention. The invention as illustrated contemplates a hermetic motor compressor unit having the casing or housing connected to the diffuser section 64. Seals (not shown) are disposed between the impeller and the dilfuser. However, this invention may be employed in systems having a motor spaced from the compressor and connected thereto by a suitable mechanical coupling.

Other arrangements, both manual and automatic, for controlling operation of the damper will suggest themselves to those skilled in the art without departing from the scope of the invention.

While I have described a preferred embodiment of the invention, it will be understood that the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

I claim:

1. In a refrigeration machine including a compressor, a condenser, an economizer and an evaporator connected to form a circuit for the flow of refrigerant, a motor for driving the compressor, a housing enclosing the motor, means forming a passage between the economizer and the motor housing to permit flow of gaseous refrigerant formed in the economizer, to the housing, means forming a passage between the housing and the compressor whereby gaseous refrigerant formed in the economizer may flow in heat transfer relation with the motor and into the compressor, and means disposed in the passage between the housing and the compressor for controlling communication between the housing and the compressor.

2. The invention set forth in claim 1 wherein the means forming the passages are positioned on opposed sides of the housing.

3. The invention set forth in claim 1 wherein said last mentioned means is operable in response to a predetermined difference in pressure between the evaporator and the economizer.

4. The method of cooling a motor controlling gas compression apparatus in a refrigeration system including a condenser, an economizer and an evaporator connected in series with the gas compression apparatus which consists in the steps of forwarding gaseous refrigerant to the condenser, liquifying the gaseous refrigerant in the condenser, forwarding the liquid refrigerant to a lower pressure zone in the economizer so as to cause portions of the liquid refrigerant to vaporize, passing the vaporized refrigerant formed in the economizer in heat exchange relation with the motor, delivering the heated vapor to the compressor and directly controlling flow of the heated vapor between the motor and the compressor to regulate pressure in the economizer.

5. The method of cooling a motor driving a compressor in a refrigeration system including a condenser, and economizer and an evaporator connected to form a closed circuit for the flow of refrigerant which consists in the steps of passing gaseous refrigerant formed in the economizer through a path including the motor and the compressor and automatically controlling flow of the gaseous refrigerant at a location between the motor and the compressor to maintain pressure of a predetermined magnitude in the economizer.

References Cited in the file of this patent UNITED STATES PATENTS 2,277,647 Jones Mar. 24, 1942 2,719,408 Penn Oct. 4, 1955 2,746,269 Moody May 22, 1956 2,776,542 Cooper Jan. 8, 1957