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Патент USA US2405042

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July 30, 1946.
.A. A. MccoRMAcK
REFRI GERAT ING APPARATUS
Filed Sept. 27, 1945
a?!
2,405,042
Patented July 30, 1946
UNITED STATES PATENT OFFICE
2,405,042
REFRIGERATING APPARATUS
Alex A. McCormack, Dayton, Ohio, assignor to
General Motors Corporation, Dayton, Ohio, a
corporation of Delaware
Application September 27, 1943, Serial No. 503,949
6 Claims. (Cl. 230—29)
2
centrifugally operated unloader valve which also
24 within which a check valve 26 is mounted. The
valve 26 is shown in its closed position in Fig. 1.
Upward movement of the check valve is limited
by suitable stop means 28. The compressed re
frigerant together with any entrained lubricant is
serves to open a passage from the inlet to the
outlet of the compressor in the event that the
compressor is started up in the wrong direction.
the outlet 30 in accordance with well known prac
tice. It will be noted that the compressor [4 is
This invention relates to refrigerating appa
ratus and more particularly to an improved com
pressor and unloading arrangement.
One object of this invention is to provide a
discharged directly into the casing It] through
mounted on a plurality of blocks 32 which are
It frequently happens that when a polyphase
compressor motor is ?rst plugged in to a poly 10 welded or otherwise secured to the bottom wall
phase system the phase connections will be wrong
of the casing it. A plurality of bolts 34 only one
in which case the motor will operate in the wrong
of which shows up in Fig. 1 holds the compressor
direction. Since there is no convenient way of
in assembled relationship with respect to the
quickly determining the correct phase connecblocks 32.
tions, it is important to provide some means to 15
The motor i2 is a polyphase motor which in
unload the compressor during full speed operacludes the usual motor stator 40 and a rotor 42.
tion of the compressor in the event that the com»
The rotor s2 is secured directly to the main com
pressor motor starts rotating in the wrong direcpressor shaft 18 as shown. The shaft i8 is pro
vided with a center bore 44 which communicates
tion.
Another object of this invention is to provide 20 with a radial bore 46 as shown. A circumferen
a centrifugally operated unloader valve which is
tial groove L19 is provided in the shaft directly in
spring biased to the closed position and in which
line with radial bore 4%. A passage 48 has been
the centrifugal means is normally out Of Contact
provided in the compressor frame as shown and
with the main valve parts during operation of
serves to connect the inlet of the compressor with
25 the bore 44. The lower portion 55 of the casing
the compressor.
.
A further Object of this invention is to provide
it! serves as a lubricant reservoir in which the
an inexpensive unloader valve which does not relubricant is subjected to a pressure correspond
quire special pipes for conveying the refrigerant
ing to the pressure at the outlet of the compres
sor. The lubricant level fluctuates during opera
through the unloader valve.
Further objects and advantages of the present 3" tion but at no time uncovers the lower end of the
invention will be apparent from the following
shaft is. Inasmuch as the lubricant is subjected
deseriptien, reference being had 130 the eeeemto a high pressure, a certain amount of it will ?nd
Danyihg drawing, Wherein a preferred form of the
its way up along the shaft l8 into the main com
present invention is clearly shown.
pression chamber. A certain amount of lubri
35 cant will also be carried along with the refriger
In the drawing:
Fig. 1 shows somewhat diagrammatically my
ant and is added to the lubricant which leaks into
improved unloader valve mounted on a li-vane
the compression chamber along the shaft l8 and
will serve to help lubricate the upper portion of
motor compressor unit;
Fig- 2 is a top View Of the unloader valve With
the compressor shaft. Inasmuch as the pressure
parts broken away so as to more clearly show 40 prevailing within the passage 48 and the circum
the arrangement of the parts; and
ferential shaft groove 49 corresponds to the suc
Fig. 3 is a sectional view showing the valve in
tion pressure, there will be a de?nite tendency
for some of the lubricant to flow upwardly along
its open position.
Referring HOW to the drawing, reference nuthe upper shaft bearing and to return to the in
meral l0 designates a substantially cup-shaped 45 let of the compressor through the passage 48.
motor-compressor casing within which a motor
The upper end of the central bore 44 is en
l2 and a Compressor N are disposed as shOWn-
larged so as to receive a valve seat element 52
The upper end of the casing lli is closed by means
which is provided with a circumferential recess
of a cap member l6 which is welded or otherwise
within which a neoprene basket 54 has been vul
secured to the cup-shaped casing 10.
50 canized prior to the insertion of the element 52
For purposes of illustration a ‘l-vane type of
.into the shaft bore. The upper end of the ele
ported rotary compressor has been shown which
ment 52 is provided. with a neoprene valve seat
includes the usual drive shaft l8, rotor 20 and
ring 56 which is vulcanized to the element 52 at
the same time that the neoprene gasket 54 is
vanes 2 2. The refrigerant to be compressed
enters the compressor through the inlet passage 55 vulcanized within the circumferential groove pro
2,405,042
3
4
vided in the member 52. While I refer to the
form, it is to be understood that other forms
use of neoprene for the valve seat 56 and the
might be adopted, as may come Within the scope
gasket 56, it is obvious that any other rubber
of the claims which follow.
like material which is uneffected by the particu
What is claimed is as follows:
lar refrigerant and lubricant used may be em (A
1. In a refrigerating system having a high
ployed without departing from the spirit of this
pressure portion in which refrigerant is main—
invention. The term “rubber-like” as used here
tained at condensing pressure and a low pressure
in is intended to include natural rubber, syn
thetic rubbers or the equivalent.
portion in which the refrigerant is maintained
a centrifugal unloading means is adapted to be
moved into and out of engagement with the ring
portion and for discharging the refrigerant at a
higher pressure into said high pressure portion,
at evaporating pressure, a rotary compressor for
A valve plate 58 which constitutes a part of 10 withdrawing refrigerant from the low pressure
56 so as to open and close the upper end of the
a
passage M.
passage on said shaft connecting the high pres
sure portion and the low pressure portion, a
pressure operated valve carried by said shaft con
trolling the flow through said shaft passage, and
centrifugal means exerting an opening force on
said valve, said centrifugal means including a
lost motion connection whereby the valve is free
With this type of valve seat and
valve plate the problem of alignment of parts
is simpli?ed. The centrifugal unloading mecha
nism includes a stamped inverted U-shaped
frame 6d, the legs of which are secured to the
upper end of the motor rotor 42 by means of the
screws 52 as shown in Fig. 2. A pin 64 is jour
naled in the side arms of the U-shaped frame ‘if’;
as shown and supports a valve operating element
56. The one end of the member 66 carries a
weight 88 and the other end of the member 66
compressor operating shaft,
a refrigerant
to move to the open position in response to pres
sure changes without hindrance from said cen
trifugal means.
2. Compression apparatus comprising a casing,
is provided with a pair of upstanding lugs 753
a compressor within said casing, a compressor
which are adapted to engage the bottom side of
the valve plate 53 so as to unseat the valve
operating shaft having a compressor unloading
passage provided therein, a valve assembly
when the compressor comes to a stop or is oper
mounted on said shaft having a Valve port com
municated with said passage, ?rst spring means
ating at slow speeds. A spring '52 biases the
valve plate 53 into valve closing position. A
spring ‘M tends to push the weighted end of
the member 6% downwardly and is strong enough
to overcome the force of the spring ‘i2 when the
centrifugal e?ect of the weight 68 drops below
The arrangement of the
Weight 63 with respect to the pivot point of the
a predetermined value.
.
biasing said valve to closed position, second spring
means for holding said valve in the open position
against the force of said ?rst spring when said
shaft is operating at a speed below a predeter
mined value, and speed responsive means for
overcoming the holding effect of said second
spring at speeds above said predetermined value.
element 66 is such that the rotation of the motor
3. In a compression system, a ported rotary
tends to cause weight {58 to fly outwardly from
compressor having an inlet and an outlet, a
the central axis of the shaft 58 and upwardly.
polyphase motor for driving said compressor, a
When the motor is operating at normal oper- ,; .,= check valve arranged in said inlet, means pro
ating speeds the valve is held closed solely by
viding a passage from the inlet of said compres
the spring 72 and the pressure difference exist
sor to the outlet of said compressor, a relief valve
ing on opposite sides of the valve plate 58 and
in said passage, spring means for holding said
the upstanding lugs 16 move downwardly far
relief valve in open position, means responsive
enough so as to be out of engagement with the 45 to rotation of said compressor for overcoming the
valve plate
This being the case the cen
force of said spring means, and means for urg
trifugal force does not interfere with opening of
ing said valve towards closed position when said
the valve in case the motor is started up in the
wrong direction in which case the pressure with
last named means overcomes said spring means.
4. In combination with a rotary compressor
in the passage 132 would very quickly exceed the
having a rotary drive shaft provided with an
pressure prevailing in the casing lfl. It will be
unloading passage communicating with the in
noted that the connection between the valve
let of the compressor, an unloader valve carried
plate 513 and the centrifugal means constitutes
by said drive shaft for controlling the flow
a form of lost motion connection and that the
through said passage comprising means forming
centrifugal force does not force the valve plate 55
a valve seat on the upper end of said shaft, a
58 to move in either direction but 'merely over
valve element cooperating with said valve seat,
comes the force of the spring M which at all
a spring holding said valve element against said
times tends to hold the valve open. This is an
seat, bracket means secured to said shaft for
important feature in a refrigerating system or
holding said spring in place, speed responsive
any other compression system using a check valve 60 means including a lever pivoted on said bracket
in the suction line and using a polyphase motor
means arranged for exerting a force on said valve
for driving a rotary compressor.
element in the valve opening direction at re
Under normal operating conditions the gas or
duced compressor speeds and arranged out of
refrigerant to be compressed enters the com
effective contact with said valve element at nor
pressor through the inlet line 24 and leaves the 65 mal operating speed of said shaft whereby said
casing it through the outlet line 8&3. When used
valve element is free to move to open position in
in a refrigerating system the outlet 86 would be
response to an abnormally high pressure in said
connected to a condenser wherein the refrigerant
passage.
would be condensed before being discharged
5. In combination with a rotary compressor of
through a conventional pressure reducing means
the type in which the direction of flow of gas
into an evaporator wherein the refrigerant
through the compressor is determined by the di
would be converted into vapor before returning
rection of rotation of the compressor, a com
to the suction inlet 24.
pressor operating shaft, a casing into which said
While the form of embodiment of the inven
compressor discharges, means forming an inlet
tion as herein disclosed constitutes a preferred
passage for said compressor, a check valve in said
2,405,042
6
inlet passage, and means for unloading said com
pressor in response to either a reduction in the
speed of said compressor or operation of the
compressor in the wrong direction, said last
named means comprising an unloader passage in
said shaft, a check valve controlling the flow of
fluid through said passage, spring means nor
mally preventing opening of said second named
check valve when said compressor is operating
in the one direction at normal speeds of rota- i
tion, and centrifugal means for overcoming said
spring means at slow speeds of said compressor
so as to unload said compressor at said slow
speeds, said centrifugal means being so construct
ed and arranged as to never exert a valve clos
ing force.
6. In a rotary compressor for withdrawing gas
from a low pressure zone and for discharging the
gas at a higher pressure into a high pressure
zone, a compressor operating shaft, a gas pas
sage in said shaft connecting the high pressure
zone and the low pressure zone, a pressure-op
erated valve carried by said shaft controlling the
flow through said shaft passage, and speed re
sponsive means exerting an opening force on
said valve, said speed responsive means includ
ing a lost motion connection whereby the Valve
is free to move to the open position in response
to pressure changes without hindrance from said
speed responsive means.
ALEX A. MCCORMACK.
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