Note: Descriptions are shown in the official language in which they were submitted.
The present invention is directed to improvemen-ts
in wobble plate compressors, especially those adapted for
use in air conditioning apparatus, particularly for auto-
motive applications.
This is a division of copending Canadian Patent
Application Serial number 269,903, filed on January 18,
1977.
A principal object of the invention is to provide
a reliable variable capacity unit at a reasonable cost. ~-
One aspect o~ this objective has to do with an improved ~-
wobble plate and drive plate mount which permits torque
loads to be transmitted independently of the pivot linkage
which connects the driving member to the drive plate.
Another aspect relates to the mechanism which anchors the
wobble plate and still another to the balancing arrangement. ~`~
U~So Patent 3,861,829 (Roberts et al~, assigned
to the same assignee as the present invention, describes
~ , .
a wobble plate compressor using controlled, under-piston
gas pressure to vary the inclination of the wobble plate,
which is supported on a universal joint. The present ~ ;~
invention is an improvement on Roberts et al in that the
drive mechanism is designed to reduce loads on certain - ;
critical elements, such as the pivot linkage, and to
simplify the unit, making it more compact and easier to
;~ assemble.
U.S~ Patent 3,552,886 (Olsen) shows a spherical
bearing or hinge ball supporting the drive plate/wobble
plate assembly.
U.S. Patents 2,980,025 (Wahlmark) and 2,964,Z34
(Loomis) both show the concept of pivoting the wobble plate
assembly to a point spaced from the drive ax:is to maintain
essentially constant clearance volume.
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Ac~ording to the present invention, there is
provided a compressor includin~ means defining a plurality
of gas working spaces each having a piston cooperating with
suction and discharge ports to compress a fluid therein, a
drive shaft, a cam mechanism driven by the drive shaft and
a wobble plate driven by the cam mechanism in a nutating
path about the drive shaft axis. Means operably connect
between the wobble plate and the individual pistons to
impart reciprocating drive to the pistons, the length of
stroke being a function of the angle at which the wobble
plate is supported relative to the drive axis~ Means is ~-
connected to the drive shaft and includes at least one
axially extending flange member. Lug means is associated
with the cam mechanism and has a poxtion in spaced, juxt-
aposed relation with a surface on the flange A pivot
` link is attached at one end thereof to the flange and at
the other end thereof to the lug means. The lug means is
spaced from the axis of the drive shaft so that the cam
mechanism i5 pivoted at a point not coincident with the -
drive shaft axis, there being no drive connection at the
drive shaft axis between the cam mechanism and the drive
shaft, the link being positioned between the flange and
the lug means so that the torque is transmitted from the
drive shaft to the cam mechanism without producing a
substantial bending moment on the pivot link.
In the accompanying drawings:
` FIGURE 1 is an elevation view, partly in cross-
`~ section, of a preferred embodiment of the present invention;
` FIGURE 2 is a rear elevation view, with portions
of the head and valve plate broken away;
FIGURE 3 is a view ~ken alony the plane of line 3-3
of FIG~E 1 with the control valve removed;
FI~ 4 is a view ~en along the plane of line 4-4
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of FIGURE ].;
FIGURE S is a cross-section view taken along the
plane of line 5-5 of FIGUR~ l;
FTGURE 6 is a cross-section view ~aken ~long the
plane of line 6-6 of FIGURE 2;
FIGURE 7 is a cross-section view taken along the
plane of line 7-7 of FIGURE 2;
FIGURE 8 is a cross-section view taken along the
plane of line 8-8 of FIGURE l;
FIGURE 9 is a plan view of the underside of the
head assembly; .
FIGURE lO is a cross-section view taken along the
plane of line 10-10 of FIGURE 9;
FIGURE 11 is a partial cross-section view taken ~ :
along the plane of line ll-].l of FIGURE 9;
FIGURE 12 is a partial cross-section view taken
along the plane of lin~ l2-l2 of FIGURE 9;
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I~IGURE 13 is a de~ailed view o~ the suction and
discharge valve as~embly as vie~7ed from und~rnea~h the valve
plate;
FIGURE 14 is a plan view o~ the valve plate;
FIGURE 15 is a cross-section view o~ the valve
plate taken along the plane of line 15-15 of FIGUR~ 14;
FIGURE 16 is an elevation view o~ the cylinder
block as viewed away from the valve plate;
FIGURE 17 is a cross section view taken along the
plane of line 17-17 of FIGURE 16;
FIGURE 18 is a plan view of the drive plate assembly;
FIGURE 19 is a cross-section view of the drive
plate assembly along the plane of line i9~19 of FIGURE 18; -~
.
FIGURE 20 is an elevation ~iew of the hinge ball;
- FI~7URE 21 is a perspective vie~i o~ the drive pla~e
.. . . ..
assembly showing the hinge ball in different ~ositions prior
to assembly; and
FIGURE 22 is a detailed cross-section view of the
lubricant flow interrupter assembly.
For pur~oses of this description, the compressor
may be.regarded as being organized in a plurality of sub-
assemblies. The mechanical Parts are all disposed within a
housing A which is generally cylindrical in cro.ss section `~
and is provided with continuous side walls and opposed open
ends into which the working parts are received. The other
major subassemblies include a cylinder block B, a wobble --
plate C, ~ drive plate D, a head assembly l~, the ~i.stons and
associated conn~ctin~ rods ~, cayacity control unit ~, d~ive
0 / 4 ?. 7 1- P,~
` ~ ~69 8 ~ ~
shafL ~ssembly ~l antl v~lve p:laL~ J.
A~ bes~ sho~n in ~IGI]RE 1, which is a ~r~ss section
view, the cylind~r block B i~ provided with a ~lurality o
spaced cylin~ers 10. The axes o~ the cylinders a~e parallel
to the drive sha~t axis, but it is understood that it is
possible to arrange such cylinders alon~ non~arallel a~es
without departing from the principles of the invention~
Also, while five cylinders are shown, the actual number is a
matter o choice in des~gn, although there is obviously some
practical upper limit and the oper~tion of the design shown
requires a~ least three cylinders since the control of the
wobble plate position depend~ on the balancing forces
resulting from the geometry of the wobble plate pivot point
with respect to the drive axis.
The cylinder block B also includes a centrally
located axial bore 12 (as shown at the left hand side of ..
.. . . .. .
FIGURE 1) forming a part of the lubrican~ distribu~ion
system which is described in more de~ail below. There is
also a counterbore 14 which receives the rear radial beari.ng
16, shown as the needle or roller bearing tyPe. Radial
bearing 16 suppor~s the rear end of drive shaft 18. The
terms "front", "rear" etc. are of course arbitrary; but in
this description the front of the compressor is the right~
hand portion of FIGURE 1 and the rear of the compressor is
the left-hand portion of FIGURE 1.
; The drive shaft 18 is supported at its front end
by a fron~ radial bearing assembly 20. The housin~ A is
provided with a central axial bore 22 ~7hich receiv~s the
front radial bearin~ 20 and a co-mterbore 7.4 formi.n~ a
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10698~i~
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CclVi~y 25 .~dcll)ted to accommoclate a seal assembly ~6 arld the
small ~-hrust ~earin~ 28. The rl~sht hand end (as viewed in
FIGllRE 1) of the housing is closed by a seal plat:e 30 which
is secured by a plurality of machine screws 31 threaded into
the annular sect;on 32 surroundlng cavity 2S at ~lle right
hand end of the housing.
The drive shaft 18 has a central axial passage 34
which interconnects with a plurality of radial passages 35,
36 and 37 used to supply lubricating oil to the drive ~late
D, front radial bearing 20, the thrust bearings and other
critical parts. There is also an inclined passage 38 through
the right hand end of the housing which provides a path for
lubricating oil and`fluid communication between the interior
- of the h~usîng and the seal cavity 25, said interior being
identified by reference numeral 40 and sometimes referre~ to
herein as the "crankcase'i. It should be noted that the ~`
crankcase is completely sealed except for the clearances
be~ween the pistons and the cylinder walls and the passages
for oil flow through the drive shaft to the bearings etc.
The seal assembly 26 at the right hand end of the drive
shaft is fluid tight and designed to increase sealing as the -
pressure rises within the crankcase, as communicated to the
seal and bearing cavity through pas~age 33. Sealing contact
is made between the rotating seal element 46 and the inside
surface of the seal plate 30.
The drive shaft is driven by means o~ a pulley 48
having a generally bell sha~ed configuration and provided
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wlth V-belt cll~a~ing flaTI~e.s 50. 'I'he pulle~ i.s keye(t a~ 52
to the tapered section 53 of thc drive shaf~ 18 and held in
place by a machine screw 54 at the end thereo~. Although
the compressor i~s described as bein~, driven by a pulley,
because one principal applica~ion for the compressor is in
an autotnotive air conditioning sys~em driven by the accessory
drive belt, it should be understood that any suitable drive
means may be provided.
The piston and connecting rod assembly F includes
pistons 56 connected to the wobble pla~e C by means,o
connecting rods 60, each having ball shaped enlarged sections
61, 62 at opposite ends thereof which may be captured in
sockets formed respectively in the pistons and wobble plate.
As viewed in FIGURE 1, the left hand end 61 o~ each connect-
ing rod is secured to the underside of the pistons and
received ~7ithin a complementary shaped socket 64 formed in a
..
thickened portio-n 65 of the ~iston 56 at the center thereof.
The o~posite ball shaped end 62 o the connecting rod is
received within a complementary socket 66 formed,in the
wobble plate C. This arrangement allows a number of degrees
of freedom, in all directions, between the respective ends
of the connecting rods both at the piston and at the wobble
'plate.
The wobble plate C is ro~atably supported on the
drive plate assembly D (see FIGURFS 18-21) which includes an
annular ~lange 67 extending radially from the drive shaft
axis and an axial hub -sec~ion 68 wlli.ch is hollow and form2d
with an internal spherical sur~ace 70 to receive the main
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J4Z7l-B~1~
~obble plate and drive plate bcaring m~m~er, r~.E~rred to
herein as hinge ball 72. ~linge ball 72 is formed wi.th a
bore 69 for drive shaft 18, oppose~l spherical surfaces 71
and opposed cylindrical surfaces 73 to al].ow insertion into
t~le hub section 6~ as shown in FIGURE 21.
The wobble plate C is mounted for relative rotary
movement with respect to the rotaT~ing drive plate assembly D
by means of three sets of bearings: the rear wobble ~late
thrust bearing i4; the front wobble plate thrust bearing 76;
and the radial wobble plate bearing 78. The i~ner race of ~:
the radial bearing 78 is mounted on the OD 80 of the axia~ .
hub section 68 of the drive plate assembly so that the drive
plate, which acts as a cam mechanism, can rotate freely with :~
respecT: to the wobble plate. In order to balance ~he assembly
under d~namic conditions, a balance weight ring 81 of sub-
stantial mass is secured to the nose o~ the hub section 68
by means of retaining ring 85. The wobble pla-te C is restrained
against rotative movemenT by means o~ anchorin~ ball element ~.
82 and cooperating slippers or pads 83. When the compressor ~;~
is in stroke, the anchoring ball slides back and forth
within a U-shaped track 84 attached to the lower portion of -
the cylinder block B in slots 86 and 87 ~see FIGURES 3 and
5).
The drive shaft assembly including plate H, which
is secured to and rotates ~7ith the drive shaft, is forTned
from two stampings, the first of which (3ho~m at 90) is
s~aced from surface 91 on the i.nsi~e of the housing by
mean~s of a l~rge thru~t bearing asscTnbly 92. A second
section 9~, which is inclined with rcspect to ~he (Irive
shait (at the same angle a5 the ma~i.mum nclina~;on pro.i~ecl
07l~71-~tJL
for maximum stroke operation o~ the compressor) is attached
to the drive shaft 18, such as by welding, and also where i~
is in contact with the first sta~ping 90. Joining the two
sta~pings at the toP are a pair of spaced apart, rearwardly
extending flanges 96, 98 (see FIGURE 8) which are adapted to
support links 100, 102 connecting the drive pla~e assembly D
to the drive shaft assembly H.
The i~proved mechanism for mounting the drive
plate D for pivotal movement with respect to the drive axis
and the link plate assembly H constitutes an important
aspect of the present invention. This arrangement virtually
eliminates all torque applied through the links 100 and 102
which, because o~ their relatively small size, are not
suitable as drive transmission elements. As best shown in
FIGURES 4 and B, the flanges 96, 98 are joined to the front
end of links 100, 102 by means of a pin 104, while the
opposite end of each link is pivotally secured to a large
lug 106 projecting from ~he front of the drive plate D by
means of a pin 110. Since the links 100, 102 each have
opposite faces in engagement with both the lug 106 on the
drive plate and flanges 96, 98 on the link plate assembly,
the torque is transmitted from flanges 96, 98 to the lu~ 106
on the drive plate without producing a bending moment on the
links 100, 102.
Although forming no part of the invention claimed
herein, another advantage of the compressor described herein
is the fact that an oil pump i5 not required. Lubrication
is accomplished by using discharge gas pressure as the
driving force to circulate oil to the various bearings and
seal assemblies which require a certain amount o~ lubrication
for efficient operation. Oil is circulated through a hollow
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dowel 112 received wi~hin central bore 12 in the cylinder
block B. Dowel 112 extends throuyh khe valve plate J and
serves to accurately locate the valve plate and head, as
well as the various gaskets, with respect to the cylinder
block. From the passage 114 in dowel 112, the oil flows
through an oil interrupter assembly 116 which includes a
stationary section 118 and a rotating section 120. As best
shown in FIGURE 22, rotation of element 120 intermittently
connects passage 122 in the s~ationary section with passage
124 in the rotating section, thus allowing flow of oil
during the time the two passages are in registration with
each other. This system controls the flow of the oil as it
passes through the axial bore 34 through drive shaft 18
and then through radial passages 35, 36, and 37 to the front
bearings and seal assembly. Without the interrupter, the `~;
oil return passage would permit an uncontrolled flow of
discharge gas into the crankcase which would drive the
. ~:
wobble plate to the m~imum stroke position and would make
effective control of the displacernent impossible to achieve.
As will be described in more detail below, the ~-
capacity control system G includes a valve member which ;-
controls the pressure maintained within the crankcase 40 and
therefore the angle of inclination of the wobble plate and
drive plate assemblies. This aspect of the compressor of
the present invention is disclosed and is also claimed in
above-identified parent application Serial number 269,903.
The refrigerant vapor will flow by the piston rings to
main~ain a certain amount of pressure within the crank
case. High crankcase pressure, acting on the underside
of the pistons, by virture of the articulated plvot point
beinc3 spaced from the drive shaft axis, causes
_ 9 _
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the drive plate c~nd wobble plate to move toward the vertical
position, decreasing stroke and capacity. Conversely,
reduction in crankcase pressure will cause the wobble plate
and drive plate assemblies to move toward a more in~lined
position, increasing stroke and capacity.
The wobble plate is never allowed to move com-
pletely to a zero stroke position; otherwise there would be
no vapor admitted to the gas working spaces and therefore
nothing for the pistons to react against in order to ~orce
the wobble ~late to an inclined position. To insure the
minimum stroke necessary a stop pin 130 i5 located in th~
drive plate 68. The stop pin will engage the drive shaft at
a point such that a minimum of 1-2% of stroke will always be
maintained.
As best shown in FIGURE 9 and 10, which are,
respectively, a bottom plan view looking at the underside of
the head E and a cross-section view, the perimeter thereof
is bounded by a downwardly extending skirt portion 140 which
is adapted to seat against a similarly shaped gas~et (not
shown) between the head and the valve plate J. Lugs 1~1,
for attaching the head to the housing, extend from the edge
thereof. Disposed inwardly from the skirt is a generally
pentagonally shaped ri.b 142 having a series of lugs 144
thereon, through which the head bolts 146 extend, a V-shaped
section 143 which forms a collectvr or sump for oil separated
from the discharge gas, and a central boss 148 for receiving
the hollow dowel 112 (FIGURE 1). It is also provided with a
generally circular boss 150 which bridges one of the ski.rt
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side walls and rib 142 to provide a housing for th~ solen~i.d
valve assembly 220, which is seated in bore 152, It should
be noted at this point tha~ the inner rib 142 separates the
discharge or high pressure region 145 from the suction or
low pressure re~ion 147. Suction gas is admitted through
port 156 into the outer region between the peripheral wall
140 and the interior wall 142, while discharge gas flows
outwardly through discharge gas port 158 located at the
upper left hand side o the interior section bounded by rib
142. 5ee also FIGURES 2, 6 and 7. A ~ort 159 for a standard
pressure relief valve is located in the high pressure region.
On the outside surface of the head are the exterior connections
for the suction and discharge lines. As shown in FIGURES 2
and 6~ a mounting plate 153 is bolted to the head at 154.
Projecting from the mounting plate are threaded connector
fittings 149, 151 for the suction and discharge gas lines
respectively. The high pressure relief valve 157 ~FIGURE 7)
extends through port 159 into the high pressure plenum. It
is well understood, if the compressor is used in an air-
conditioning or refrigeration application the discharge line
would connect to a condenser, an expansion device, an evaporator
and the suction line, in series flow relation.
The head assembly has a series of inwardly project-
ing lugs 160 which support an oil separator screen 162 (see
FIGURES 1, 6 and 7) constructed o~ a mesh or screen-type
material, between the valve plate 114 and the head in the
high pressure region, A substantial portion of the lubri-
cating oil coal~sces on the scr~en as it flows into the
discharge 7,0ne l~ounde~l by rib 142 and drains by gravi ty into
~ 1 1
a pock~t shaped area 164 de~ined by wall section 143, which,
although shown in FIGURE 9 at the four o'clock position,
will actually be the lowest point within the interior of rib
142 when the compressor is oriented properly. As best shown
in FIGURE 12, which is a cross-section view taken along the
plane of line 12-12 of FIGURE 9, there is a drilled hole 166
communicating with the lower portion o~ the oil collecting
pocket 164 and there is a shallow groove 168 (see also
FIGURE 11) which ;s formed in a rib 172 extending from the
pocket 164 to the boss 148 through which the hollow dowel
extends. The groove 168 provides a channel for lubricating
oil running from the pocket 164 to a crescent shaped relief
section 174 cut in the interior waIl of the central boss ~ -
148. From there it flows into a small cham~er 176 ~IGURE 1)
adjacent the dowel 112 and then through the bore 114 to the
space 180 between the dowel and the stationary flow interrupter
element 118. The latter is fixed within a counterbore and
urged axially to the right by means of the spring element
182 against the mating surface of the rotating oil interrupter
element 120. As best showrl in FIGURE 22, t~ese elem~nts
have passages 122, 124 which are spaced from the drive axis
at th~ same radius. As passage 124 in the rotating interrupter
element 120 comes into registration with the passage 122 in
the stationary element 118 a small quantity of oil will flow
to the axial bore 34 in the drive shaft 18 and then through
the series of radial ports in the drive shaft, as earlier
described.
The construction of the valve plate J and associated
suction and discharge valves is best sho~m in FIGURES 2, 13,
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14 ~nd 15. Xeferring to FI~URE 1~, the valve pla-~e ha4 a
series of discharge ports 190 which communicate with the
discharge zone 145 defined by the interior rib 142 of the
head. A series of suction ports 192, are spaced radially
outwardly from the discharge ports and communicate with
suction region 147. Reed or flapper-type discharge valves
194 are secured to the top surface of t~e valve plate by
rivets 196 which also hold suction v~lves 198 on the bottom
of the valve plate.
Since the rivets extend through holes 199 below
the bottom surface of the valve plate, a plurality of dimples
200 are formed in the top surface o the cylinder block to
accomodate them. The suction valves 198, (FIGURE 13) which
are formed with an arcuate section 202 overlying the suction
ports 192 at the bottom surface of the valve plate, include
a large elon~ated opening 204 in the center thereof to allow
. . :
flow of gas to the discharge port 190. The discharge valves
are furnished with individual valve stops 206 ~FIGURE 1)
which limit the upward travel of the valves.
In FIGURE 14 it will be noted that the valve ~late
is also provided with a small kidney shaped port 208, port
210 directly underneath it and another port 212 to the left
of port 210 (FIGURES 14 and 15). These ports ~orm part of a
gas flow path related to operation o~ the capacity control
valve ~. The details o this arrangement will be described
below.
The cylinder block, as best sho~m in FIGURES 16
and ]7 has a number o convex lands 21~ which en~age the
~ 4
machined inside surface 21~ of thc housirl~7 A The five
cylinders 10 are equally spaced from each other, radially
and circum~erentially. A passage 218 parallel to the cylinder
axis, extends through the cylinder block and re~,isters with
the kidney shaped opening 208 in the valve plate mentioned
above. This passage transmits pressure existing with the
crankcase 40 through the valve plate to a region which is on
one side of the capacity control port 210 in valve plate J
and can be closed by the solenoid valve 220 (see FIGURE 5).
As best shown in FIGURE 5, solenoid valve 220
includes a housing 222, a coil 224 and an armature 226. The
armature is connected to a valve member 228 located in the
central region of a diaphragm 230. When the coil is energized~
the armature moves to the left pulling the valve member and
uncovering control port 210. When de-energized, the diaphragm
forces the valve member to the right, closing the port 210.
l~hen the solenoid valve is open, crankcase pressure is
transmitted through passage 218 and port 208 into a circular
chamber 232 between the diaphragm and the top surface of the
valve plate adjacent to control port 210.
A suction responsive control valve 240 controls
flow from the crankcase to the suction cavity (when the
solenoid valve is open) and includes a sealed evacuated
bellows 242 biased by spring 244 and a valve member 246
adapted to seat against the control port 210. Suction
pressure is transmitted to the chamber 248 surrounding the
bellows in the following manner.
With reference to FI~IIRE 16, the bore 250 in
cylinder block B (which receives the suction pressure
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control valve 240) is associated with a relieved area or
undercut surface 252 (FIGURES 5, 16 and 17). This area
forms a gas passage 253 between the valve plate and the
block extending from port 212 in the valve plate, which is
in registration with the distal portion thereof, to chamber
248 surrounding bellows 242. Port 212, in turn, is in
registration with the suction plenum 147 in the head and is
located a~ a point designated by 254 at (*) in FIGURE ~,
just to the left of bore 152.
The higher pressure crankcase gas thus flows along
the following path: from crankcase 40 through passage 218,
diaphragm chamber 232, control port 210, bellows chamber
248, passage 253, port 21~ and into the suction plenum at
pOillt 254.
Operation :~
I~ will be assumed that, initially, the co~pressor
is in its ~ull stroke operation, substantially as depicted
in FIGURE 1. . ::
As the pulley 48 is driven, torque is transmittçd ~ :
to the drive shaft 18. The link plate, connected to the
drive shaft will rotate and the flanges 96, 98 transmit the
torque through the links 100, 102 to the drive plate without
producing a bending moment on the links. As the drive plate
rotates, it acts as a cam driving the wobble plate in a
nutating path. The anchor ball 82 slides back and forth in ~:
.~ track 8~ as pistons reciprocate in cylinders 10.
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As described in the a~orementioned U. S. patent
3,861,829, the crankcase pressure, created by gas blowing by
the pistons, is modulated to control the angle of the drive
plate and therefore the length of stroke. The geometry of
the pivot points of the links 100, 102 with respPct ~o the
drive axis is such that an increase in crankcase pressure
will act against the underside of the pistons, and the
resultant force will cause the wobble plate to move to a
more vertical position, decreasing stroke length and capacity.
Conversely, a decrease in crankcase pressure will allow the
force of the gas in the working spaces to move the wobble
plate to a more inclined position, increasing stroke length
and capacity.
Thus hy controlling crankcase pressure, the capacity
of the compressor may be precisely controlled in response to
some external variable; in this case, suction pressure.
Assume now that the solenoid valve 220 is open and some
predetermined suction pressure exists. Since this suction
pressure is enveloping the bellows, as previously described,
the position of the bellows valve member responds to suction
pressure. If the suction pressure should rise9 due perhaps
to an increase in the load, the bellows con~racts opening
valve member 246. This allows more gas to flow through port
210 from the crankcase to suction, decreasing the crankcase
pressure and increasin~ stroke length. If suction pressure
drops, indicating reduced load, the bellows will expand
because of spring 244 and reduce flow throug~h port 210 ~rom
the crankcase to suction This, of coursc, will increase
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cranlccase pressure reduciny, stroke len~h and capacity. The
solenoid valve is basically an on-of control. When de-
energized, i~ will close por~ 210 causing the crankcase
pressure to rise and thus move the wobble plate to minimum
stroke position. The stop-pin wlll not permit zero stroke
and there will be permitted just enough recîprocation of the
pistons to admit some gas to the working spaces, to maintain
some flow of oil through the system, and to maintain suf~icient
~ressure differen~ial across ~he compressor so that it will
go into stroke when the solenoid valve is energized.
,
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