US 2373909 A
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Description (OCR text may contain errors)
April 17, 1945.
M. P. PENN REFRIGERATING APPARATUS Filed Sept. "25, 1941 Patented Apr. '17, 1945 umrao, STATES REFRIGERATING APPARATUS Melvin 1?. Penn, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, at corporation of Delaware Application September 25, 1941, Serial No. 412,306
This invention relates to electric motor-com- .pressor units for refrigerating apparatus and.
other applications, and more particularly to unloading means therefor.
In the Lipmann Patent 1,899,341, an unloading valve is opened upon starting by the attraction of the increased field around the motor setup by the high starting current which acts upon a magnetic actuating member. This arrangement, however, makes it necessary that the motor be energized before the unloading valve. is opened. Even after the unloading valve is opened the compressor is not unloaded, since suflicient gas must \pass through the opened unloading valve to equalize the pressures upon opposite sides thereof befo e the unloading is complete. Obviously these spects are highly undesirable. It is an. object of my inventionto provide an unloading valve arrangement which opens and equalizes the pressures to complete the unloading during the idle period and which is held closed during the normal operation of the compressor by the magnetic field set-up during the normal operation of the electric compressor motor.
. It is another object of my invention to provide an unloading valve arrangement actuated by the electric compressor motor magnetic field which is free from chattering.
It is another object of my invention to provide a more simple, more reliable and less expensive unloading arrangement in which a magnetic member by its mass holds .open the unloading valve when the electric motor is deenergized and which is energized by the stray magnetic field of the electric motor to close the unloading valve when the motor is energized.
To attain these objects I have provided an electric motor-compressor unit for example, such 7 as the sealed unit type used in refrigerating systems wherein a pivoted'member carrying a valve provided with a face of a rubber-like material is more than counterbalanced by a portion of magnetic material which is in close proximity to the electric motor and is attracted by the stray magnetic field thereof to overcomethe effects of gravity andto attract the magnetic material to cause the lever to be pivoted to positively move the valve to closed position and retain it there during the energization of the electric motor.
Further objects and advantages of the present invention will be apparent from the followingdescription, reference beinghad to the accompanying drawing, wherein a preferred form of a the present invention is clearly shownf In the drawing:
. Fig. 1 is a vertical sectional view of a sealed motor-compressor unit embodying one form of my invention together with a dlagrammaticrepresentation of the remaining elements of a re- 5 frigerating system;
Fig. 2 is a fragmentary view showing the un-' loading. valve held in the closed position; and
Fig.3 is an elevational view of the armature of the unloadingvalve- I Referring now to the drawing and more particularly to Fig. 1, there is shown a sealed motor-. compressor unit including a lower casting member which telescopes over an upper casing member 22 which in turn fits on the motor- 5 compressor frame 24. This motorcompressor frame 24 is'cup-shapedand carries the stator 26 of the electric motor. Fas'tened to the lower face of this cup-shaped frame 24 is a rotary compressor 26 having a member 28 provided with an 20 inlet passage 30 and also provided with an outlet passage connected to the pipe 32 which conducts ,the compressor outlet upwardly to the electric motor portion of the sealed unit.
, The frame member 24 carries a, bearing por- 26 tion 34 which supports the drive shaft 35 carrying the rotor 36 of the electric motor and extending into the compressor 26. The frame member 24 carries a sleeve 38 connecting with a passage leading to the inlet passage 30. -The upper end of this .sleeve 38 is machined and ground to provide a plane surface to serve as a valve seat. The passage through the sleeve 38 and the passage 40 constitutes an unloading passage since theyconnect the interior of the sealed unit, into which the compressor discharges, with the compressor inlet passage 30. Thus when the passage in the sleeve 38 isvopen the compressor is unloaded and merely operates to circulate gas through the compressor and theinterior of the sealed unit without pumping against any mavterial pressuredifi'erential.
In order to load the compressor, I have provideda valve 42 having an insert M of a suitable rubber-like material which will withstand aging as well as the effects of the gas and the lubricant within the sealed casing. There are several different classes of such material, such as one known as Neoprene or Chloroprene rubber. The valve 42 is connected to a lever 46 which is provided with a forked end engaging a groove 4 provided upon the valve 42. This lever 46 is Div, V oted upon a pin .48 as shown in Fig: 2, to a stationary member 50 which fits upon the bearing portion 34- of the motor-compressor frame 24 and rests against the shoulder clearly shown on the drawing. This member also has an aperture which forms a guide holding the valve 42 in apis sumcient to hold the valve 42 in open position so as to permit complete unloading of the compressor whenever the electric motor is dee'nergized. If it is not desired to rely upon gravity, 9.
fine wire spring 56 may be coiledabout the pivot pin 40 and have one end anchored against the member Eli with the other end pressing against the lever 46 to hold the valve open by the spring tension. In either case, however, the member of magnetic material is necessary.
This member of magnetic material is preferably located substantially in the position shown so that it is sumciently near the rotor and stator to be most strongly attracted by the stray magnetic field necessarily occurring in that particular area due to the conventional design of the electric motor. The strength of this stray magnetic field increases with the load and the current consumed.
By using this stray magnetic field one of the prin-' cipal objections to magnetic unloaders is overcome, since no additional current is required for the operation of the unloader. particular type of magnetic action, and the rubber-like valve face the usual dimculties due to altemating current chattering may be avoided.
Alsoduetothis' I mature of magnetic material of sufficient weight- -which the liquid refrigerant may be forwarded under the control of a suitable liquid flow control device 34- to a refrigerant evaporating means 86. In the evaporating means 88 the refrigerant evaporated under reduced pressure which is main-. tained by the operation of the sealed unit which withdraws evaporated refrigerant from the evaporating means 68 through the suction conduit 88 which may be provided with a filter or moisture absorber III and connected by means of the tubing l2 and a resilient metal connection II with the compressor inlet passage till.
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 electric motor-compressor unit'comprising an electric motor and a compressor driven by the electric motor, said unit being provided with an unloading passage connecting the compressor inlet and outlet, a pivoted member, a valve normally open during idle periods and connected to said pivoted member for closing said unloading passage, said member being provided with an ar-' and leverage to cause the lever to be tilted to a position to open the valve when the'motor is deenergized and so located adjacent the motor as to be in the magnetic field of the motor when.
energized to operate the lever to close the valve uponwenergization of the motor andto. hold the This is probably due to a considerable extent upon the location of the magnetic member II as near as'possible to the air gap between the rotor 88 and the stator 28. However, when chattering does of the motor-compressor unit to a refrigerating system the sealed unit is shown connected to a coniienser 60 where compressed refrigerant may he condensed and collected in a receiver 62 from valve closed throughout the continued enersization of the motor.
2. An electric motor-compressor unit compris- I 3 for holding the valve open throughout each idle period of the motor, said armature being located 7 immediately adjacent the air gap between the rotor and the stator so as to be attracted directly MELVIN P. PENN.