Note: Descriptions are shown in the official language in which they were submitted.
- 1 - 2~ 9~9
TYD-9402
RECIPROCATORY PISTON TYPE COMPRESSOR
WITH A ROTARY VALVE
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reciprocatory
piston type multi-cylinder refrigerant compressor for a
refrigeration system, and more particularly, it relates
to a reciprocatory piston type compressor provided with
a rotary valve element for controlling the suction of a
refrigerant gas before compression from a suction
chamber into respective cylinder bores; the rctary valve
may also control discharge of the refrigerant gas after
compression from respective cylinder bores toward a
discharge chamber.
2. Description of the Related Art
Reciprocatory piston type refrigerant compressors
such as a wobble plate operated reciprocatory piston
type variable displacement compressor, and a swash plate
operated reciprocatory piston type fixed displacement
compressor are conventionally used for compressing a
refrigerant circulating through a refrigeration system
of e.g., an automobile air conditioner. The
reciprocatory piston type compressor is provided with
an axial cylinder block having a plurality of cylinder
bores arranged parallel with a drive shaft of the
compressor and a plurality of single headed or double
headed pistons reciprocated in the respective cylinder
bores to compress the refrigerant in the form of a gas.
For example, the compressor having single headed
pistons is also provided with a housing attached to one
of the axial ends of the cylinder block via a valve
plate to define a suction chamber therein from which the
refrigerant gas is supplied into respective cylinder
bores so as to be compressed, and a discharge chamber
'- 2-- 2~ .~9
therein toward which the compressed refrigerant gas is
discharged from the respective cylinder bores. When the
refrigerant gas is supplied from the suction chamber
into the respective cylinder bores, the gas passes
through suction ports formed in the valve plate and
closably opened by suction valves arranged so as to be
in contact with one end face of the valve plate on the
side thereof confronting respective cylinder bores. ~he
suction valves are opened when a pressure level in each
cylinder bore is lower than a given low pressure level.
Similarly, when the compressed refrigerant gas is
discharged from the respective cylinder bores toward
the discharge chamber, the compressed refrigerant passes
through discharge ports formed in the valve plate and
closably opened by discharge valves arranged so as to
be in contact with the other end face of the valve
plate on the side thereof confronting the discharge
chamber. The discharge valves are opened when the
pressure level in each cylinder bore is higher than a
given high pressure level. It should, however, be noted
that these suction and discharge valves arranged on
opposite sides of the valve plate of the conventional
compressor have the form of a flapper or reed valve,
respectively. Namely, each of the suction and discharge
valves in the flapper form is made of a thin elastic
plate material so that the valve is constantly
elastically urged toward the closing position thereof.
Therefore, the flapper valve must always be moved from
the closing to opening position thereof against the
elastic force exerted by the valve per se, and
accordingly during the opening of the suction or
discharge valve in the flapper form, a considerable
amount of refrigerant pressure loss occurs thereby
- lowering the volumetric efficiency of the compressor.
Further, when the suction or discharge valve in the
flapper form returns to the closing position thereof,
it strikes against the end face of the valve plate and
2~ 9
produces a loud noise, and may additionally be apt to be
damaged or broken.
U.S. Patents Nos. 4,749,340, 4,76~,091, and
4,781,540 disclose several constructional improvements
of the flapper valve that enhance the volumetric
efficiency of the reciprocatory piston type compressor
and solve the noise problem. Nevertheless, a further
innovative improvement of the function and performance
of the suction and discharge valves of the reciprocatory
piston type compressor has been requested.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to
provide a reciprocatory piston type refrigerant
compressor provided with a novel valve element
accommodated therein capable of eliminating the above-
mentioned problems encountered by the conventional
flatter form valve.
Another object of the present invention is to
provide a reciprocatory piston type multi~cylinder
refrigerant compressor provided with a noise free rotary
valve element smoothly rotated together with a drive
shaft of the compressor so as to control an appropriate
supply of a refrigerant from a suction chamber to
respective cylinder bores and thereby prevent the loss
of pressure during compression of the refrigerant.
A further object of the present invention is to
provide a reciprocatory piston type multi-cylinder
refrigerant compressor provided with a noise free rotary
valve element smoothly rotated together with a drive
shaft of the compressor to control not only an
appropriate supply of the refrigerant from a suction
chamber into respective cylinder bores but also an
appropriate discharge of the compressed refrigerant
from respective cylinder bores toward a discharge
chamber and thereby maintain a high volumetric
compressor efficiency.
In accordance with one aspect of the present
- 4 - 2~
invention, there is provided a reciprocatory piston type
compressor for compressing a refrigerant of a
refrigeration system that comprises:
a cylinder block having a central axis thereof, a
cylindrical central bore formed to be coaxial with the
central axis, and a plurality of axial cylinder bores
arranged around and in parallel with the central axis,
each axial cylinder bore having at least one bore end
through which the refrigerant enters therein, and is~0 discharged therefrom;
a housing unit air-tightly connected via a
partition wall plate to opposite axial ends of the
cylinder block for defining therein a suction chamber
for the refrigerant before compression fluidly
communicating with the cylindrical central bore of the
cylinder block, and a discharge chamber for the
refrigerant after compression located around and
isolated from the suction chamber;
a rotatable drive shaft having axial ends thereof
rotatably supported by bearings seated in the housing
unit and the cylinder block;
a plurality of reciprocatory pistons fitted in the
plurality of axial cylinder bores of the cylinder block;
each piston being reciprocated in one of the plurality
of cylinder bores for suction, compression, and
discharge of the refrigerant;
a swash plate-operated piston drive mechanism
arranged around the rotatable drive shaft for driving
the plurality of reciprocatory pistons in the plurality~0 ~f cylinder bores in cooperation with the drive shaft;
a constant fluid communication means formed between
each of the plurality of cylinder bores and the central
bore of the cylinder block; and
a rotary valve means arranged in the central bore
of the cylinder block and attached to the drive shaft
so as to be rotated together with the drive shaft; the
rotary valve means being provided with a fluid
2~ ; J ~ . 9
passageway formed therein for controlling a supply of
the refrigerant before compression from the suction
chamber of the housing means to at least one of the
plurality of cylinder bores via the constant fluid
communication means while the cylinder bore is in the
suction phase to draw therein the refrigerant before
compression in cooperation with the reciprocatory
pistons in response to the rotation of the drive shaft
and the rotary valve means.
1 n In accordance with another aspect of the present
invention, there is provided a reciprocatory piston type
compressor for compressing a refrigerant of a
refrigeration system that comprises:
a cylinder block having a central axis thereof, a
first cylindrical valve chamber bored coaxially with
the central axis, and a pluraIity of axial cylinder
bores arranged around and in parallel with the central
axis; each axial cylinder bore having at least one bore
end through which the refrigerant enters therein, and~0 is discharged therefrom;
a housing unit air-tightly connected via a
partition wall plate means to opposite axial ends of the
cylinder block for defining therein a suction chamber
for the refrigerant before compression fluidly
communicating with the first cylindrical valve chamber
of the cylinder block, and a discharge chamber for the
refrigerant after compression located around and
isolated from the suction chamber; the housing unit
further defining a second cylindrical valve chamber~0 coaxial with the first cylindrical valve chamber;
a rotatable drive shaft having axial ends thereof
rotatably supported by bearings seated in the housing
unit and the cylinder block;
a plurality of reciprocatory pistons fitted in the
plurality of axial cylinder bores of the cylinder block;
each piston being reciprocated in one of the plurality
of cylinder bores for suction, compression, and
~ 6 -~ 2 ~ 9
discharge of the refrigerant;
a swash plate-operated piston drive mechanism
arranged around the rotatable drive shaft for driving
the plurality of reciprocatory pistons in the plurality~ of cylinder bores in cooperation with the drive shaft;
a first constant fluid communication means formed
between each of the plurality of cylinder bores and the
first cylindrical valve chamber of the cylinder block;
a second constant fluid communication means formed
between the discharge chamber and the second cylindrical
valve chamber of the housing unit; and
a rotary valve unit arranged in the first and
second valve chambers of the cylinder block and the
housing unit and attached to the drive shaft so as to
rotate together with the drive shaft;
. the rotary valve unit provided with a first fluid
passageway formed therein for controlling a supply of
the refrigerant before compression from the suction
chamber of the housing means to at least one of the
plurality of cylinder bores via the first constant
fluid communication means while the cylinder bore is in
the suction phase drawing therein the refrigerant before
compression in cooperation with the reciprocatory
pistons in response to the rotation of the drive shaft,
and a second fluid passageway formed therein for
controlling a discharge of the refrigerant after
compression from at least one of the plurality of
cylinder bores to the discharge chamber via the first
and second means for forming constant fluid
communication while the cylinder bore is in the
discharge phase so as to discharge the refrigerant
after compression in cooperation with the reciprocatory
pistons in response to the rotation of the drive shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and
advantages of the present invention will be made more
apparent from the ensuing description of the preferred
--7 - 2~
embodiments thereof in conjunction with the accompanying
drawings wherein:
Fig. l is a longitudinal cross-sectional view of a
reciprocatory piston type refrigerant compressor
provided with a rotary valve element according to a
first embodiment of the present invention;
Fig. 2 is a front view of a partition wall plate of
the compressor, taken along the line ~ -~ of Fig. 1
and illustrating an arrangement of radial passageways
formed in an end face thereof;
Fig. 3 is a perspective view of a rotary valve
element incorporated in the compressor of Fig. 1:
Fig. 4 is a plan view of the rotary valve element
of Fig. 3, illustrating an arrangement of a suction
refrigerant passageway formed therein;
Fig. 5 is a partial schematic and cross-sectional
view of a portion of a reciprocatory piston type multi-
cylinder refrigerant compressor, illustrating a
constructional variation from the embodiment of Fig. 1;
Fig. 6 is a view similar to Fig. 5, illustrating
another constructional variation from the embodiment of
Fig. 1;
Fig. 7 is a partial schematic cross-sectional view
of a portion of a reciprocatory piston type compressor,
illustrating a further constructional variation from the
embodiment of Fig. 1;
Fig. 8 is a partial schematic view of a portion of
a reciprocatory piston type compressor, illustrating a
still further constructional variation from the
embodiment of Fig. 1;
Fig. 9 is a partial schematic view of a portion of
a reciprocatory piston type compressor, illustrating a
further constructional variation from the embodiment of
Fig. 1;
Fig. lO is a longitudinal cross-sectional view of a
reciprocatory piston type refrigerant compressor
provided with a rotary valve element according to a
--8-- 2~,79~-9
second embodiment of the present invention;
Fig. 11 is a perspective view of a cylindrical
valve retainer element incorporated in the compressor of
Fig. lO;
Fig. 12 is a longitudinal cross-sectional view of a
reciprocatory piston type refrigerant compressor
provided with a rotary valve element according to a
third embodiment of the present invention;
Fig. 13 is a partial another longitudinal cxoss-
sectional view of the compressor of Fig. 12,
illustrating the construction of a rotary valve element
incorporated in the compressor;
Fig. 14 is a front view of a partition wall plate
of the compressor of Fig. 12, illustrating an
arrangement of radial passageways formed in one end
face thereof;
Fig. 15 is a perspective view, in a small scale, of
a rear housing of the compressor of Fig. 12;
Fig. 16 is a perspective view of a rotary valve
element incorporated in the compressor of Figs. 12 and
13;
Fig. 17 is a cross sectional view of the rotary
valve element of Fig. 16, illustrating an arrangement
of a suction refrigerant passageway and a discharge
refrigerant passageway formed therein; and
Fig. 18 is a graphical view, illustrating a
relationship between a piston stroke and an pressure in
a cylinder bore of the compressor of Fig. 12.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figs. 1 through 4, illustrating the
first embodiment of the present invention, a
reciprocatory piston type refrigerant compressor
includes a cylinder block 1 having a central axis. The
cylinder block 1 is provided with axially opposite ends,
a central bore la extended coaxially with the central
axis and formed as a valve chamber for receiving a
later-described rotary valve element, and a plurality
_ 9 ~
of ( e.g., five in the embodiment ) cylinder bores lb
arranged equiangularly around and in parallel with the
central axis. One of the axial ends, i.e., a front end
of the cylinder block 1 is air-tightly closed by a
front housing 2, and the other end, i.e., a rear end of
the cylinder block 1 is air-tightly closed by a rear
housing 4 via a partition wall plate 3. The front
housing 2 defines a crank chamber 5 axially extending
in front of the front end of the cylinder block 1. The
rear housing 4 defines therein a centrally arranged
cylindrical suction chamber 17 for a refrigerant before
compression, and an annularly extending discharge
chamber 18 for a refrigerant after compression arranged
so as to surround and be isolated from the suction
chamber 17.
A drive shaft 6 axially extending through the crank
chamber 5 is rotatably supported by bearings 6a and 6b
seated in a central bore of the front housing 2 and the
central bore la of the cylinder block 1. The drive shaft
6 has a rotor 7 fixedly mounted thereon to be rotated
together and axially supported by a thrust bearing 6c
arranged between an inner end of the front housing 2
and the frontmost end of the rotor 7. The rotor 7 has a
support arm 8 extending from a rear part thereof to
provide an extension in which an elongated through-bore
8a is formed for receiving a lateral pin 8b slidably
movable in the through-bore 8a. The lateral pin 8b is
connected to a swash plate 9 arranged around the drive
shaft and is capable of changing an angle of inclination
thereof with respect to a plane perpendicular to the
rotating axis of the drive shaft 6.
A sleeve element lO axially and slidably mounted on
the drive shaft 6 is arranged adjacent to the rearmost
end of the rotor 7, and is constantly urged toward the
rearmost end of the rotor 7 by a coil spring 11
arranged around the drive shaft 6 at a rear portion
thereof. The sleeve element lO has a pair of laterally
- lo-- 2~ . ~ '~ 9
extending trunnion pins lOa on which the swash plate 9
is pivoted so as to be inclined thereabout.
The swash plate 9 has an annular rear face and a
cylindrical flange to support thereon a non-rotatable
wobble plate 12 via a thrust bearing 9a. The non-
rotatable wobble plate 12 has an outer periphery
provided with a guide portion 12a in which a long bolt
16 is fitted to prevent any rotational play of the
wobble plate 12 on the swash plate 9, and the wobble
plate 12 is operatively connected to pistons 15 axially
and slidably fitted in the cylinder bores lb, via
connecting rods 14. When the drive shaft 6 is rotated
together with the rotor 7 and the swash plate 9, the
wobble plate 12 on the swash plate 9 is non-rotatably
wobbled to cause reciprocation of respective pistons 15
in the cylinder bores lb. In response to the
reciprocation of the pistons 15, the refrigerant is
drawn from the suction chamber 17 into respective
cylinder bores lb and compressed therein. The
compressed refrigerant is discharged from respective
cylinder bores lb toward the discharge chamber 18 from
which the refrigerant after compression is delivered to
the condenser of a refrigeration system.
During the operation of the compressor, when a
change in a pressure differential appears between a
suction pressure in each cylinder bore lb and a pressure
prevailing in the crank chamber 5, the stroke of each
piston 15 is changed, and therefore, the angle of
inclination of the swash plate 9 and the wobble plate
12 is changed. The pressure in the crank chamber 5 is
adjustably changed by a conventional solenoid control
valve ( not shown in Fig. 1 ) housed in an extended
portion of the rear housing 4.
The afore-mentioned central suction chamber 17 of
the rear housing 4 has an opening formed in an end wall
of the rear housing 4 so that the suction chamber 17 is
able to receive a refrigerant therein when the
~ 3 9 ?9
refrigerant returns from the exterior of the compressor.
The suction chamber 1~ is communicated with the central
bore la of the cylinder block 1 via a central bore 3a
of the partition wall plate 3 arranged so as to be
coaxial with and having a bore diameter equal to the
central bore la of the cylinder block. The partition
wall plate 3 is provided with a plurality of ( five in
this embodiment ) radial passageways 21 formed to
extend radially from the central bore 3a thereof, as
best shown in Fig. 2, An end of each radial passageway
21 is located to open toward the rearmost end of one of
the axial cylinder bores lb of the cylinder block 1.
A cylindrical rotary valve element 22 is smoothly
and rotatably accommodated in the central bore la of
the cylinder block 1 and the central bore 3a of the
partition wall plate 3, and an axially inner end of the
rotary valve element 22 is fixedly attached by a key 23
to an end of the drive shaft 6 extending into the
central bore la of the cylinder block. Thus, the rotary
valve element 22 is rotated together with the drive
shaft 6. The drive shaft 6 and the rotary valve element
22 of the compressor according to the present embodiment
may be rotated in either the CW direction or CCW
direction. A rear end of the rotary valve element 22,
i.e., an end opposite to the above-mentioned inner end
is supported by a thrust bearing 24 seated in an
annular step of the suction chamber formed in the inner
wall of the rear housing 4.
As best shown in Figs. 3 and 4, the cylindrical
rotary valve element 22 is provided with a fluid
passageway 25 including an axial blind bore 25a
centrally formed therein, a groove 25b formed in the
cylindrical surface thereof to circumferentially extend
over approximately a half of the circumference thereof,
and a radial bore 25c formed to provide a fluid
communication between the central bore 25a and the
circumferential groove 25b. The fluid passageway 25 of
-12- 2~, ,S~,9
the rotary valve element 22 is provided to control the
suction of the refrigerant from the suction chamber 17
of the rear housing 4 into respective cylinder bores lb.
Namely, during the rotation of the rotary valve element
22, while the circumferential groove 2Sb of the rotary
valve element 22 is met with the radial passageways 21
of the cylinder bores lb in which the suction stroke of
the pistons 15 is carried out, fluid communication is
provided between these radial passageways 21 and the
suction chamber 17 through the fluid passageway 25.
The discharge chamber 18 of the rear housing 4
arranged radially outside the suction chamber 17 can be
communicated with respective cylinder bores lb via
discharge ports 18a formed in the partition wall plate
3 and discharge valves 19 in the flapper form disposed
in the discharge chamber 18 to close the discharge
ports 18a. The movement of the discharge valves 19 are
restricted by valve retainers l9a.
The above-described reciprocatory piston type
compressor is incorporated in a refrigeration system of
an air-conditioner such as an automobile air-
conditioner to compress the refrigerant and deliver the
compressed gas into the refrigeration system.
The operation of the compressor with the rotary
valve element 22 will be described hereunder.
When the drive shaft 6 of the compressor is rotated
about the rotating axis thereof by an external drive
power, the swash plate 9 is rotated together and wobbled
around the drive shaft 6 due to an inclination of the
swash plate 9 with respect to a plane perpendicular to
the rotating axis of the drive shaft 6. The wobbling
motion of the rotating swash plate 9 causes a
synchronous wobbling of the non-rotatable wobble plate
12, so that the respective pistons 15 connected to the
wobble plate 12 via the connecting rods 14 are
reciprocated in the respective cylinder bores lb. During
the reciprocation of the pistons 15, when each of the
- 13
pistons 15 starts to slide in the corresponding
cylinder bore lb from top dead center ( T.D.C ) toward
bottom dead center ( B . D . C ) thereof to conduct a
suction stroke thereof, the rotary valve element 22
rotating together with the drive shaft 6 in e.g., the
CCW direction shown in Fig. 4 is brought into a position
whereat the leading end of the circumferential groove
25b of the fluid passageway 25 thereof is met with the
radial passageway 21 of the cylinder bore lb, and
accordingly the radial passageway 21 of the cylinder
bore lb is fluidly communicated with the suction
chamber 17 via the fluid passageway 25 of the rotary
valve element 22. Thus, the refrigerant gas is drawn
from the suction chamber 17 into the cylinder bore lb
through the fluid passageway 25 and the radial
passageway 21.
Subsequently, when the piston 15 is moved to the
B.D.C in the cylinder bore lb, the tail end of the
circumferential groove 25b of the rotating rotary valve
element 22 passes the radial passageway 21 of the
cylinder bore lb in which the piston 15 arrives at the
B . D . C . . Thus, the radial passageway 21 of the cylinder
bore lb is disconnected from the suction chamber 17 by
the rotary valve element 22. Then, when the piston 15
starts to slide in the cylinder bore lb from the B.D.C
toward the T.D.C thereof, the refrigerant gas drawn
into the cylinder bore lb is compressed by the piston
15, and therefore, a pressure prevailing in the
cylinder bore lb is gradualIy increased to a level
capable of urging the discharge valve 19 to move from
the closing toward the open~position thereof.
Accordingly, the compressed refrigerant is discharged
from the cylinder bore lb into the discharge chamber 18
via the discharge port 18a of the partition wall plate 3.
From the foregoing description, it will be
understood that the rotary valve element 22 rotating
together with the drive shaft 6 controls the supply of
l4~ 3
the refrigerant from the suction chamber 17 of the rear
housing 4 toward the respective cylinder bores lb to
thereby achieve an appropriate compression of the
refrigerant gas and a discharge of the compressed
refrigerant gas.
According to the present embodiment of Figs. 1
through 4, since the rotary valve element 22 is
constructed as a rotary suction control valve rotating
together with the drive shaft 6 of the compressor, it
is possible to obtain a wide opening area of the
suction control valve compared with the conventional
flapper-form suction control valve. Therefore, the
volumetric efficiency of the compressor per se can be
raised due to a lowering of pressure loss of the
refrigerant in each of the plurality of cylinder bores
lb of the compressor.
Further, the rotary suction valve element 22 can
significantly reduce noise during the operation thereof
compared with the conventional flapper-form suction
control valve. In addition, since the rotary suction
valve element 22 performs the suction control operation
thereof by smooth rotation in the valve chamber, damage
or breakage and abrasion of the rotary suction control
valve do not easily occur for a long operation time
thereof. Thus, an improvement of the suction valve
mechanism of the reciprocatory piston type compressor
over the conventional flapper-form suction control
valve can be achieved.
Figure 5 illustrates a modification of the
reciprocatory piston type compressor of Fig. 1. Namely,
when the rotary valve element 22 is incorporated in the
compressor as a suction control valve, the conventional
flapper-form suction control valves are arranged so as
to be in contact with the partition wall plate 3.
Therefore, the discharge ports 18a of the partition
wall plate 3 through which the compressed refrigerant
is discharged from the respective cylinder bores lb
- 15- ~ yg
toward the discharge chamber 18 may be provided in a
position such that the center of each discharge port 18a
is in correct alignment with the central axis of the
corresponding cylinder bore lb. Thus, each reciprocatory
piston lS may have a projection 15a at the head thereof
so as to be engageable with the corresponding discharge
port 18a in response to the movement of the piston 15
toward top dead center ( T.D.C ) thereof, and
accordingly the piston lS can always be moved in the
0 cylinder bore lb to a position permitting a minimal gap
between the piston head thereof and the inner end face
of the partition wall plate 3. Therefore, the amount of
compressed refrigerant gas remaining in the cylinder
bore lb without being discharged therefrom is minimal so
that the volumetric efficiency of the compressor can be
increased.
Figure 6 illustrates another modification of the
reciprocatory piston type compressor of Fig. l. Namely,
in the construction of the compressor of Fig. 6, the
radial passageways 21 are arranged in the cylinder
block 1 instead of the afore-described partition wall
plate 3. As a result, the length of each radial
passageway 21 can be made shorter, and accordingly, any
compressed refrigerant gas remaining in the radial
passageway 21 at the time the piston 15 comes to the
end of the discharge stroke thereof can be reduced to
the minimal amount. Consequently, the volumetric
efficiency of the compressor can be raised.
Figure 7 illustrates a further modification of the
reciprocatory piston type compressor of Fig. 1. Namely,
in the construction of the compressor of Fig. 7, the
drive shaft 6 is provided with a flange portion 61 to
support one end of a coil spring 26 the other end of
which is in contact with the rotary valve element 22 to
thereby always urge the rotary valve element 22 toward
the thrust bearing 24 seated in the rear housing 4.
Thus, any axial play of the rotary valve element 22 can
- 16-
2 ~ ~
be cancelled to ensure a smooth rotation of the rotary
valve element 22, and accordingly, abrasion and seizure
of the rotary valve element 22 can be prevented. Further.
difficulty in controlling the dimension and size of the
rotary valve element 22 during the production and
assembly stages thereof can be mitigated.
The coil spring 26 of Fig. 7 may be arranged
between the rotary valve element 22 and a radial bearing
63 shown in Fig. 8, which is arranged so as to
0 rotatably support the drive shaft 6 instead of the
bearing 6b of Fig. 1 or Fig. 7. The bearing 63 is
provided with a flanged inner race against which the
end of the coil spring 26 is bore, and therefore the
drive shaft 6 can be made of a straight member having
no flange. Namely, the assembly of the rotary valve
element 22 can be simplified compared with the
compressor of Fig. 7.
Figure 9 illustrates another modification in which
the spring 26 urging the rotary valve element 22 is
supported by a thrust bearing 65 seated on a step lc of
the cylinder block 1. Thus, assembly of the rotary valve
element 22 can be simple similarly to the embodiment of
Fig. 8.
Referring to Figs. lO and 11 illustrating a second
embodiment of the present invention, the reciprocatory
piston type compressor is different from the compressor
of the first embodiment shown in Fig. 1 through 4 in
that a cylindrical hollow sleeve element 44 is fixedly
accommodated in the central bore la of the cylinder
block 1 and the central bore 3a of the partition wall
plate 3 to rotatably receive the rotary valve element
22 therein, and therefore, the thrust bearing 24 used
with the compressor of the first embodiment is
eliminated. Thus, the same or like elements as those of
the compressor of the first embodiment are designated by
the same reference numerals as those of Fig. 1 through
4.
~ 2~ 3~ 9
As best shown in Fig. 11, the cylindrical hollow
sleeve element 44 is provided with a plurality of open
windows 44a radially formed in the cylindrical wall
thereof and an annular extension 44b formed at an end
thereof seated in a shoulder portion of the rear
housing 4.
The open windows 44a of the cylindrical hollow
sleeve element 44 are arranged in such a manner that
when the sleeve element 44 is assembled in the cylinder
block 1 and the rear housing 4, the plurality of open
windows 44a are in correct registration with the
respective radial passageways 21 of the partition wall
plate 3. Therefore, the fluid passageway 25 of the
rotary valve element 22 can be sequentially communicated
with the radial passageways 21 and the corresponding
cylinder bores lb of the cylinder block 1 in response to
the rotation of the rotary valve element 22 within the
cylindrical sleeve element 44.
The above-mentioned annular extension 44b of the
cylindrical hollow sleeve element 44 is provided for
axially supporting the rotary valve element 22.
The provision of the cylindrical hollow sleeve
element 44 is effective for allowing the rotary valve
element 22 to smoothly rotate therein together with the
drive shaft 6, because when the hollow sleeve element 44
is made of a metallic bearing material, this hollow
sleeve element 44 is able to function as a cylindrical
slide bearing for the rotary valve element 22 during the
rotation of the rotary valve element 22. Consequently,
any loss of power for driving the drive shaft 6 of the
compressor from an external'drive source such as an
automobile engine can be prevented.
Also, the occurrence of an unfavorable problem such
as abrasion and seizure of the rotary valve element 22
can be avoided.
The cylindrical hollow sleeve element 44 is
assembled in a cylindrical bore-like valve chamber
--1 8 ~, ~y9
portion of the compressor formed by the combination of
the cylinder block 1, the partition wall plate 3 and
the rear housing 4, and therefore, it is often difficult
for the rotary valve element 22 to obtain a complete
air-tight sealing characteristics. Nevertheless, because
of provision of the cylindrical hollow sleeve element
44 in which the rotary valve element 22 is rotatably
housed, the sealing characteristics of the rotary valve
element 22 can be improved over the embodiment of the
l~ afore-described first embodiment of Figs. 1 through 4
and thus, good suctiorl control of the rotary valve
element 22 can be obtained.
Moreover, difficulty in controlling the dimension
and size of the above-mentioned cylinder block 1, the
partition wall plate 3, the rear housing 4, and the
rotary valve element 22 during the production and
assembly stage of the compressor can be ri n; rized.
Figures 12 through 18 illustrate a third embodiment
of the present invention, and the same and like
elements and portions as those of the first embodiment
of Figs. 1 through 4 are designated by the same
reference numerals.
Referring to Figs. 12 through 16, the rotary valve
element 22 is arranged in the valve chamber defined by
the central bore la of the cylinder block 1, the
central bore 3a of the partition wall plate 3, and the a
portion of an internal cylindrical wall 43 ( Fig. 15 )
of the rear housing 4. It is to be noted that in the
present third embodiment the rotary valve element 22 is
provided as a rotating valve having the ability to
control both suction and discharge of the refrigerant
with respect to the plurality of cylinder bores lb of
the cylinder block 1. Therefore, the compressor has no
flapper-form valve. It should, however, be noted that
the suction, compression, and discharge operations are
conducted by reciprocation of the pistons 15 in the
cylinder bores lb caused by the swash and wobble plates
- 19-
8 and 9 when driven by the drive shaft 6 in the same
manner as the compressor of the first embodiment.
The description of the construction and operation
of the rotary valve element 22 capable of exhibiting
both suction and discharge control performance will be
given below.
Referring to Figs. 13, 16, and 17, the rotary valve
element 22 attached to an end of the drive shaft 6 is
provided with a fluid passageway 25 including an axial
blind bore 25a centrally formed therein, a
circumferential groove 25b formed in the cylindrical
outer surface thereof, and a radial passageway 25c
providing a connection between the bore 25a and the
groove 25b for controlling the supply of the
refrigerant before compression from the suction chamber
17 to the respective cylinder~bores lb while the
respective cylinder bores lb are in the suction stage.
The rotary valve element 22 is also provided with
an axially extending groove-li~e passageway 27 formed
in the cylindrical outer surface thereof. The
passageway 27 is located adjacent to but spaced from
one end, i.e., a leading end of the circumferential
groove 25b of the fluid passageway 25 when considering a
predetermined rotating direction of the rotary valve
element 22, shown by an arrow " A " in Fig. 17. The
spacing between the passageway 27 and the leading end of
the circumferential groove 25b is selected and designed
in the manner described later.
As shown in Fig. 13, one end of the axial groove-
like passageway 27 is disposed adjacent to the rearmostend of the rotary valve element 22, and the other end
thereof is disposed at a position whereat the passageway
27 is capable of communicating with the respective
radial passageways 21 of the partition wall plate 3 (
Fig. 14 ) during the rotation of the rotary valve
element 22.
Referring to Figs. 13 and 15, the cylindrical wall
2~ 3~l9
~3 of the rear housing 4 is provided with an internal
annular groove 41 at a position capable of being
constantly exposed to the above-mentioned axial groove
27 of the rotary valve element 22, and an appropriate
number of radial bores 42 connecting between the
discharge chamber 18 and the internal annular groove 41
of the cylindrical wall 43 of the rear housing 4.
In accordance with the above-described construction
and arrangement of the rotary valve element 22, when
the rotary valve element 22 is rotated together with the
drive shaft 6, and when the axial passageway 27 comes
to positions whereat it is met with the radial
passageway 21 of the cylinder bore lb wherein the
discharge stroke of the piston 15 is proceeded, the
cylinder bore lb is fluidly communicated with the
discharge chamber 18 of the rear housing 4 via the
radial passageway 21 and the axial passageway 27 of the
rotary valve element 22. The fluid communication of the
axial passageway 27 of the rotary valve element 22 with
respective cylinder bores lb sequentially occurs
thereby permitting the compressed refrigerant to be
discharged from the cylinder bores lb toward the
discharge chamber 18 in response to the rotation of the
rotary valve element 22. Namely, the rotary control
valve element 22 has a function of controlling the
discharge of the compressed refrigerant gas from the
respective cylinder bores lb toward the discharge
chamber 18 during rotation thereof together with the
drive shaft 6 in addition to the afore-mentioned suction
control function.
When the rotary valve element 22 is provided with
both the fluid passageway 25 and the axial passageway
27, a predetermined spatial relationship between these
two fluid passageways is established to obtain
appropriate control of both suction and discharge of
the refrigerant with respect to respective cylinder
bores lb. Namely, as best shown in Figs. 17 and 18, the
- 21-- 2'~J ~ ~ ~ 9
circumferential groove 25b of the fluid passageway 25 is
formed in the outer circumference of the rotary valve
element 22 in such a manner that in response to the
rotation of the element 22 together with the drive
shaft 6 in the direction shown by an arrow " A ", the
leading end of the circumferential groove 25b is brought
into fluid communication with one of the cylinder bores
lb via the associated radial passageway 21 when the
piston 15 in the cylinder bore lb is moved away from
the top dead center ( T.D.C ) thereof by an angular
amount "~ " thereby causing a delay of a commencement
of the suction stroke with respect to the cylinder bore
lb.
At this stage, since the axial passageway 27 of the
rotary valve element 22 is arranged to be
circumferentially spaced from the leading end of the
circumferential passageway 25b, re-expansion of the
compressed refrigerant remaining in the cylinder bore lb
occurs during the time period corresponding to the
above-mentioned angular amount "O " of the rotation of
the rotary valve element 22.
On the other hand, the circumferential passageway
25b of the rotary valve element 22 is extended so that
the tail end thereof passes another cylinder bore lb
2~ wherein the piston 15 reaches the bottom dead center (
B.D.C ) thereof when the piston 15 is moved away from
the B.D.C by a predetermined amount corresponding to an
angular amount "~ "' of the rotation of the rotary'valve
element 22. Namely, commencement of the compression
stroke within the cylinder bore lb is delayed as
clearly shown in Fig. 18. Figure 18 illustrates that the
delay of the commencement of the compression stroke
with respect to the cylinder bore lb can compensate for
pressure loss in the suction of the refrigerant caused
by the above-mentioned delay in the commencement of the
suction stroke with respect to the cylinder bore lb.
In accordance with the above-mentioned arrangement
~ 22- 2 ~ ,
of the fluid passageway 25 ànd the circumferential
passageway 27 of the rotary valve element 22, it is
ensured that the circumferential outer surface of the
rotary valve element 22 is provided with a
predetermined length of land portion between the axial
passageway 27 and the leading end of the
circumferential passageway 25b as clearly shown in Fig.
17. Thus, each of the cylinder bores lb does not
simultaneously communicate with both suction and
discharge chambers 17 and 18 of the rear housing 4 via
the rotary valve element 22, and accordingly, the
compressed refrigerant does not directly leak from the
cylinder bore lb toward the suction chamber 17.
When the rotary valve element 22 is provided with
both suction and discharge control functions, pressure
loss of the refrigerant gas during the operation of the
reciprocatory piston type compressor can be
significantly lowered compared with the compressor
provided with the conventional flapper-form suction and
discharge valves, and accordingly, the volumetric
efficiency of the compressor can be considerably
enhanced. Further, an elimination of the flapper-form
valves from the compressor can significantly contribute
to a reduction of noise during the operation of the
compressor and to a reduction in valve damage or
breakage during the operation life of the compressor.
Further, since the single rotary valve element 22
controls the suction and discharge of the refrigerant
with respect to the plurality of cylinder bores lb, it
is possible to reduce the number of elements for
constructing one reciprocatory piston type compressor
while simplifying the construction of the compressor.
Thus, the manufacturing cost of the reciprocatory
piston type compressor can be lowered.
In the described embodiments, the reciprocatory
piston type compressor is provided with a plurality of
cylinder bores in which a plurality of single-headed
- 23- 2 ~ t 9
pistons are reciprocated to conduct the suction,
compression, and discharge operation under the control
of the rotary valve element. Nevertheless, it should be
understood that the rotary valve element formed as a
5 rotary suction control valve or a rotary suction and
discharge control valve can equally be applicable to
the other reciprocatory piston type compressor provided
with a plurality of double-headed reciprocatory pistons
reciprocated by a swash plate mechanism having a fixed
inclination angle. Namely, in the case of the double
headed piston type compressor, two rotary valve elements
are attached to opposite ends of a drive shaft that is
rotated to thereby causing rotating and wobbling motions
of the swash plate in the swash plate chamber provided
in the center of the cylinder block.
From the foregoing description, it will be
understood that according to the present invention, a
reciprocatory piston type refrigerant compressor having
high volumetric efficiency and capable of exhibiting a
noise free and a damage free operation with a long
operation life can be realized.
It should, however, be noted that many variations
and modifications will occur to persons skilled in the
art without departing from the spirit and scope of the
present invention as claimed in the appended claims.
