U.S. patent application number 13/143503 was filed with the patent office on 2011-11-03 for reciprocating compressor and refrigerating apparatus having the same.
Invention is credited to Jin-Kook Kim, Kyeong-Ho Kim, Young-Hwan Kim, Kyoung-Jun Park.
Application Number | 20110265510 13/143503 |
Document ID | / |
Family ID | 42316938 |
Filed Date | 2011-11-03 |
United States Patent
Application |
20110265510 |
Kind Code |
A1 |
Kim; Jin-Kook ; et
al. |
November 3, 2011 |
RECIPROCATING COMPRESSOR AND REFRIGERATING APPARATUS HAVING THE
SAME
Abstract
Disclosed are a reciprocating compressor and a refrigerating
apparatus having the same, a ball bearing (300) can be easily
stably installed between thrust surfaces (213, 227) of a cylinder
block (210) and a crank shaft (220) so as to enhance efficiency of
the compressor. Also, a ball bearing (300) can be installed by
being inserted into thrust surfaces (213, 227) so to shorten a
moment arm that much, thereby decreasing a frictional loss at a
journal bearing surface (215), resulting in an energy efficiency of
the reciprocating compressor and the refrigerating apparatus having
the same. In addition, as an oil hole (226c) of the crank shaft
(220) is veiled by the journal bearing surface (215) of the
cylinder block (210), even if a ball bearing (300) is employed, oil
leaked between the thrust surfaces (213, 227) can be reduced,
thereby further enhancing the efficiency of the compressor and the
refrigerating apparatus having the same.
Inventors: |
Kim; Jin-Kook; (Changwon,
KR) ; Kim; Kyeong-Ho; (Changwon, KR) ; Kim;
Young-Hwan; (Changwon, KR) ; Park; Kyoung-Jun;
(Changwon, KR) |
Family ID: |
42316938 |
Appl. No.: |
13/143503 |
Filed: |
December 7, 2009 |
PCT Filed: |
December 7, 2009 |
PCT NO: |
PCT/KR2009/007283 |
371 Date: |
July 6, 2011 |
Current U.S.
Class: |
62/498 ;
417/437 |
Current CPC
Class: |
F04B 27/0423 20130101;
F04B 27/0404 20130101; F04B 39/0246 20130101 |
Class at
Publication: |
62/498 ;
417/437 |
International
Class: |
F25B 1/00 20060101
F25B001/00; F04B 19/22 20060101 F04B019/22 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 7, 2009 |
KR |
1020090001214 |
Jan 7, 2009 |
KR |
1020090001216 |
Claims
1. A reciprocating compressor comprising: a cylinder block provided
with a shaft bearing hole to define a journal bearing surface and
having a thrust surface on an upper end of the shaft bearing hole;
a crank shaft provided with a plate-shaped extending portion
extending wider than the shaft bearing hole of the cylinder block,
a lower surface of the plate-shaped extending portion defining a
thrust surface conformable to the thrust surface of the cylinder
block; and a bearing assembly disposed between the thrust surface
of the cylinder block and the thrust surface of the crank shaft,
the thrust surfaces facing each other, and support the crank shaft
in the shaft direction with respect to the cylinder block, wherein
at least one of the thrust surface of the cylinder block and thrust
surface of the crank shaft is provided with a bearing locking
portion for locking at least part of the bearing assembly in the
radial direction.
2. The compressor of claim 1, wherein the beating locking portion
is configured as an annular protrusion to be contactable with an
outer circumferential surface or an inner circumferential surface
of the bearing assembly, or comprises at least three or more
arcuate protrusions along a circumferential direction.
3. The compressor of claim 1, wherein a bearing insertion groove is
formed at least one of the thrust surface of the cylinder block or
the thrust surface of the crank shaft so that at least part of the
bearing assembly is inserted therein.
4. The compressor of claim 3, wherein a height of the bearing
insertion groove in the shaft direction is defined such that a
minimum interval in the shaft direction between the thrust surface
of the cylinder block and the thrust surface of the crank shaft is
not greater than a height of the bearing assembly in the shaft
direction.
5. The compressor of claim 1, wherein at least one oil passage is
formed within the crank shaft, at least one oil groove is formed at
an outer circumferential surface of the crank shaft, the oil
passage and the oil groove communicating with each other via at
least one oil discharge hole and at least one oil introduction
hole, wherein the oil introduction hole is formed at an oil groove,
of the at least one oil groove, communicated between the thrust
surface of the cylinder block and the thrust surface of the crank
shaft, at least part of the oil introduction hole being veiled by
the journal bearing surface of the cylinder block.
6. (canceled)
7. The compressor of claim 5, wherein the oil groove has a
plurality of inclination angles, wherein an inclination angle at a
portion adjacent to the oil introduction hole, among the plurality
of inclination angles, is relatively smaller than an inclination
angle at a portion away from the oil introduction hole.
8. The compressor of claim 5, wherein an edge between the journal
bearing surface and the thrust surface of the cylinder block is
chamfered or round.
9. The compressor of claim 5, wherein a bearing insertion groove in
which part of the bearing assembly is inserted is formed either at
the thrust surface of the crank shaft or at the thrust surface of
the cylinder block.
10. The compressor of claim 1, wherein the bearing assembly
comprises a ball cage fotuied in an annular shape with a preset
thickness, and at least three balls each having a diameter greater
than the thickness of the ball cage and coupled to the ball cage;
wherein a bearing insertion groove in which part of the bearing
assembly is inserted is formed either at the thrust surface of the
crank shaft or at the thrust surface of the cylinder block, a depth
of the bearing insertion groove being deep enough that at least
part of the ball cage is inserted.
11. (canceled)
12. The compressor of claim 10, wherein the bearing assembly
comprises a washer in an annular shape fondled at least one of both
sides of the balls in the shaft direction to be contactable with
the balls, at least one washer being located at an outer periphery
of the bearing insertion groove.
13. The compressor of claim 12, wherein a thickness of the washer
located at the outer periphery of the bearing insertion groove is
not thinner than a height of the bearing locking portion.
14. The compressor of claim 1, wherein a thrust surface without the
bearing locking portion formed, of the thrust surface of the
cylinder block or the thrust surface of the crank shaft, the thrust
surfaces facing each other, is formed to be flat.
15. The compressor of claim 14, wherein the crank shaft is provided
with a journal bearing surface inserted into the shaft bearing hole
of the cylinder block, wherein a bearing supporting portion greater
than an outer diameter of the journal bearing surface is integrally
twined or assembled between the journal bearing surface and the
plate-shaped extending portion of the crank shaft.
16. The compressor of claim 14, wherein the bearing supporting
portion has a length in the shaft direction which is not longer
than the length of the bearing assembly in the shaft direction.
17. The compressor of claim 14, wherein an oil pocket larger than a
diameter of the shaft bearing hole is formed at an edge between the
journal bearing surface and a flat surface in the shaft direction
of the cylinder block, wherein the bearing supporting portion and
the bearing locking portion support the bearing assembly in the
radial direction such that a center of the bearing assembly in the
shaft direction is located out of the range of the oil pocket.
18. The compressor of claim 14, wherein the bearing assembly
comprises a ball cage formed in an annular shape with a preset
thickness, and at least three balls each having a diameter greater
than the thickness of the ball cage and coupled to the ball
cage.
19. The compressor of claim 18, wherein washers are provided at
both side surfaces of the balls in the shaft direction to be
contactable with the balls, each washer being supported by the
bearing supporting portion or the bearing locking portion in the
radial direction.
20. (canceled)
21. A reciprocating compressor in which a crank shaft for
transferring a rotational force is supported by a cylinder block in
a radial direction and a shaft direction, a connecting rod is
coupled to the crank shaft to convert a rotary motion into a linear
motion, and a piston coupled to the connecting rod reciprocates
within a cylinder to compress a refrigerant, wherein at least one
oil passage is formed within the crank shaft, at least one oil
groove is formed at an outer circumferential surface of the crank
shaft, the oil passage and the oil groove communicating with each
other via at least one oil discharge hole and at least one oil
introduction hole, wherein the oil introduction hole is formed at
an oil groove, of the at least one oil groove, communicated between
the thrust surface of the cylinder block and the thrust surface of
the crank shaft, at least part of the oil introduction hole being
veiled by the journal bearing surface of the cylinder block.
22. (canceled)
23. The compressor of claim 21, wherein the oil groove has a
plurality of inclination angles, wherein an inclination angle at a
portion adjacent to the oil introduction hole, among the plurality
of inclination angles, is relatively smaller than an inclination
angle at a portion away from the oil introduction hole.
24. A refrigerating apparatus comprising: a compressor; a condenser
connected to a discharge side of the compressor; an expansion
apparatus connected to the condenser; and an evaporator connected
to the expansion apparatus and to a suction side of the compressor,
wherein the compressor is configured according to claim 1.
Description
TECHNICAL FIELD
[0001] The present invention relates to a reciprocating compressor
and a refrigerating apparatus having the same, and more
particularly, a reciprocating compressor having a ball bearing
installed between thrust surfaces of a cylinder block and a crank
shaft, and a refrigerating apparatus having the same.
BACKGROUND ART
[0002] In general, a hermetic compressor is a compressor provided
with a motor unit disposed in a hermetic container for generating a
driving force, and a compression unit operated by receiving the
driving force from the motor unit. The hermetic compressors may be
categorized into a reciprocating type, a rotary type, a vane type
and a scroll type according to the compression mechanism with
respect to a refrigerant as a compressible fluid.
[0003] The reciprocating compressor is configured such that a crank
shaft is coupled to a rotor of a motor unit, a connecting rod is
coupled to the crankshaft of the motor unit and a piston is coupled
to the connecting rod, so that the piston linearly reciprocates
within a cylinder to thereby compress a refrigerant.
[0004] The reciprocating compressor is configured such that a shaft
portion of a crank shaft is inserted into a cylinder block to be
supported in a radial direction and simultaneously an eccentric
mass portion is laid on the cylinder block to be supported in a
shaft direction as well, thereby forming a journal bearing surface
and a thrust bearing surface between the crank shaft and the
cylinder block. Hence, how to reduce the frictional loss between
the crank shaft and the cylinder block as much as possible acts as
an important factor on enhancing energy efficiency of the
compressor. To this end, an oil passage is formed at the crank
shaft so that oil pumped from an oil feeder can evenly be supplied
to each bearing surface via the oil passage.
[0005] However, the related art reciprocating compressor has
limitation on the reduction of frictional loss due to the
surface-contact between the thrust surfaces. Taking into account of
this, a technology has recently been proposed in which separate
bearings such as ball bearings are installed such that the thrust
surfaces are point-contactable with each other.
DISCLOSURE OF INVENTION
Technical Problem
[0006] However, in the related art reciprocating compressor, if at
least part of a bearing installed between thrust surfaces of the
cylinder block and the crank shaft moves in a radial direction, an
assembly operation may not easily be done or the bearing may be
slipped out of its original position while the compressor is
driven, thereby interfering with the driving or crushing with the
crank shaft and the like, causing noise or damage.
[0007] Furthermore, as a separate bearing such as a ball bearing is
installed between the thrust surfaces, an interval between the
thrust surfaces becomes wider by the height of the bearing, which
increases moment and accordingly lowers the compressor efficiency.
In addition, oil sucked up via the oil passage is excessively
discharged via the ball bearing. Consequently, the oil may not be
sucked up to the upper end of the crank shaft to thereby cause a
drastic frictional loss with the connecting rod, thereby lowering
the compressor efficiency.
[0008] Therefore, an object of the present invention is to provide
a reciprocating compressor capable of facilitating assembly when
installing a ball bearing between the thrust surfaces and also
ensuring a stable operation, and a refrigerating apparatus having
the same.
[0009] Another object of the present invention is to provide a
reciprocating compressor capable of reducing a frictional loss in a
shaft direction between the crank shaft and the cylinder block by
virtue of installation of a bearing assembly such as a ball bearing
between thrust surfaces, and simultaneously enhancing efficiency by
reducing moment due to a gas force within the cylinder and allowing
a smooth supply of oil up to the cam portion, and a refrigerating
apparatus having the same.
Solution to Problem
[0010] To achieve those objects of the present invention, there is
provided a reciprocating compressor including a cylinder block
provided with a shaft bearing hole to define a journal bearing
surface and having a thrust surface on an upper end of the shaft
bearing hole, a crank shaft provided with a plate-shaped extending
portion extending wider than the shaft bearing hole of the cylinder
block, a lower surface of the plate-shaped extending portion
defining a thrust surface conformable to the thrust surface of the
cylinder block, and a bearing assembly disposed between the thrust
surface of the cylinder block and the thrust surface of the crank
shaft, the thrust surfaces facing each other, and support the crank
shaft in the shaft direction with respect to the cylinder block,
wherein at least one of the thrust surface of the cylinder block
and thrust surface of the crank shaft is provided with a bearing
locking portion for locking at least part of the bearing assembly
in the radial direction.
[0011] In another aspect of the present invention, there is
provided a reciprocating compressor in which a crank shaft for
transferring a rotational force is supported by a cylinder block in
a radial direction and a shaft direction, a connecting rod is
coupled to the crank shaft to convert a rotary motion into a linear
motion, and a piston coupled to the connecting rod reciprocates
within a cylinder to compress a refrigerant, wherein at least one
oil passage is formed within the crank shaft, at least one oil
groove is formed at an outer circumferential surface of the crank
shaft, the oil passage and the oil groove communicating with each
other via at least one oil discharge hole and at least one oil
introduction hole, wherein the oil introduction hole is formed at
an oil groove, of the at least one oil groove, communicated between
the thrust surface of the cylinder block and the thrust surface of
the crank shaft, at least part of the oil introduction hole being
veiled by the journal bearing surface of the cylinder block.
[0012] In one aspect of the present invention, there is provided a
refrigerating apparatus including, a compressor, a condenser
connected to a discharge side of the compressor, an expansion
apparatus connected to the condenser, and an evaporator connected
to the expansion apparatus and to a suction side of the compressor,
wherein the compressor is provided with a bearing assembly for
supporting a shaft direction between a cylinder block and a crank
shaft, part of the bearing assembly being supported in a shaft
direction by being inserted into the crank shaft while the other
portion of the bearing assembly being supported in a radial
direction by a bearing locking portion provided at the cylinder
block, wherein an oil introduction hole for guiding oil from the
inside of the crank shaft to the outside thereof is formed to be
veiled by a journal bearing surface.
Advantageous Effects of Invention
[0013] In the reciprocating compressor in accordance with the
present invention and the refrigerating apparatus having the same,
a ball bearing can be easily stably installed between thrust
surfaces of the cylinder block and the crank shaft so as to enhance
efficiency of the compressor. Also, a ball bearing can be installed
by being inserted into thrust surfaces so as to shorten a moment
arm that much, thereby decreasing a frictional loss at a journal
bearing surface, resulting in an energy efficiency of the
reciprocating compressor and the refrigerating apparatus having the
same. In addition, as the oil introduction hole for guiding oil
from the inside of the crank shaft to the outside thereof is veiled
by the journal bearing surface of the cylinder block, oil leaked
between facing surfaces in the shaft direction can be reduced,
which allows an effective lubrication between a cam portion and the
connecting rod and simultaneously effective cooling of a motor
unit, resulting in further enhancement of the efficiency of the
compressor and the refrigerating apparatus having the same.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1 is a longitudinal sectional view showing an exemplary
reciprocating compressor according to the present invention;
[0015] FIG. 2 is a front view of a crank shaft of FIG. 1;
[0016] FIG. 3 is a perspective view of a cylinder block of FIG.
1;
[0017] FIGS. 4 and 5 are a perspective view showing a bearing
locking portion of the cylinder block of FIG. 3, wherein FIG. 4
exemplarily shows an annular bearing locking portion and FIG. 5
exemplarily shows an arcuate bearing locking portion;
[0018] FIG. 6 is a longitudinal sectional view showing an installed
state of ball bearings between the cylinder block and the crank
shaft of FIG. 1;
[0019] FIG. 7 is a disassembled perspective view showing the
cylinder block, the crank shaft and the ball bearing of FIG. 1;
[0020] FIG. 8 is a longitudinal sectional view showing an assembled
state of the cylinder block, the crank shaft and the ball bearings
of FIG. 1;
[0021] FIGS. 9 and 10 are graphs showing changes in force applied
to each journal bearing surface when installing ball bearings at
thrust surfaces in the reciprocating compressor of FIG. 1, wherein
FIG. 9 is a graph showing the change in a force applied to the
journal bearing surface when the ball bearings are exposed between
the thrust surfaces, and FIG. 10 is a graph showing the change in a
force applied to the journal bearing surface when the ball bearings
are inserted into bearing insertion grooves;
[0022] FIG. 11 is a schematic view showing a first oil groove
extending from the crank shaft of FIG. 1;
[0023] FIG. 12 is a schematic view showing a location of an oil
discharge hole of FIG. 1;
[0024] FIG. 13 is a longitudinal sectional view showing thrust
surfaces of a cylinder block and a crank shaft in accordance with
another embodiment of the supporting structure of the ball bearings
of FIG. 1;
[0025] FIG. 14 is a view taken along the line I-I of FIG. 13;
[0026] FIGS. 15 to 17 are longitudinal sectional views showing
different embodiments of the supporting structure of the ball
bearing according to FIG. 13;
[0027] FIG. 18 is a schematic view showing an exemplary
refrigerator having the reciprocating compressor according to the
present invention;
[0028] FIG. 19 is a front view showing another embodiment of the
crank shaft of FIG. 1;
[0029] FIG. 20 is a longitudinal sectional view showing an
assembled state of a cylinder block, a crank shaft and ball
bearings in accordance with FIG. 19;
[0030] FIG. 21 is a schematic view showing a size (configuration,
specification) of a bearing supporting portion of FIG. 19; and
[0031] FIG. 22 is a schematic view showing another embodiment of
the bearing supporting portion of FIG. 19.
BEST MODE FOR CARRYING OUT THE INVENTION
[0032] Hereinafter, with reference to the accompanying drawings,
description will be made in detail of a reciprocating compressor
and a refrigerating apparatus having the same in accordance with
embodiments of the present invention.
[0033] As shown in FIG. 1, a reciprocating compressor according to
the present invention may include a motor unit 100 installed inside
a hermetic container 1 and performing a rotation motion, and a
compression unit 200 disposed above the motor unit 100 and
compressing refrigerant by a rotational force received from the
motor unit 100.
[0034] The motor unit 100 may be implemented as a constant-speed
motor which is rotatable in a forward direction, a constant-speed
motor which is rotatable both in forward and reverse direction, or
an inverter motor. The motor unit 100 may include a stator 110
elastically installed in the hermetic container 1 with being
supported by a cylinder block 210 to be explained later, and a
rotor 120 rotatably installed inside the stator 110.
[0035] The compression part 200 may include a cylinder block 210
having a cylinder 211 forming a compression space and elastically
supported by the hermetic container 1, a crank shaft 220 inserted
into the cylinder block 210 to be supported in a radial direction
and a shaft direction and coupled to the rotor 120 of the motor
unit 100 for transferring a rotational force, a connecting rod 230
rotatably coupled to the crank shaft 220 for converting a rotation
motion into a linear motion, a piston 240 rotatably coupled to the
connecting rod 230 and linearly reciprocating within the cylinder
211 so as to compress a refrigerant, a valve assembly 250 coupled
to an end of the cylinder block 210 and having a suction valve and
a discharge valve, a suction muffler 260 coupled to a suction side
of the valve assembly 250, a discharge cover 270 coupled to
accommodate a discharge side of the valve assembly 250, and a
discharge muffler 280 communicating with the discharge cover 270
for attenuating discharge noise of a discharged refrigerant.
[0036] With the configuration of the reciprocating compressor
according to the present invention, when power is applied to the
stator 110 of the motor unit 100, the rotor 120 is rotated with the
crank shaft 220 by interaction with the stator 110, and the
connecting rod 230 coupled to a cam portion 223 of the crank shaft
220 performs an orbiting motion. The piston 240 coupled to the
connecting rod 230 then linearly reciprocates within the cylinder
211 to compress a refrigerant and discharges the compressed
refrigerant via the discharge cover 270. The refrigerant discharged
via the discharge cover 270 then flows into a refrigerating cycle
via the discharge muffler 280. The series of processes are
repeated.
[0037] The crank shaft 220 is rotated so that the oil feeder O
installed at a lower end of the crank shaft 220 pumps up oil
contained in an oil storing unit of the hermetic container 1. Such
oil is sucked up via the oil passage of the crank shaft 220 so as
to be supported to each bearing surface. Here, the oil is partially
dispersed at the upper end of the crank shaft 220 so as to cool the
motor unit 100.
[0038] Hereinafter, a construction of a crank shaft for pumping up
oil stored in an oil storing unit of the hermetic container 1 will
be described.
[0039] That is, as shown in FIG. 2, the crank shaft 220 may include
a shaft portion 221 coupled to the rotor 120 and inserted into a
shaft bearing hole 212 of the cylinder block 210 so as to be
supported by the cylinder block 210 in a radial direction, an
eccentric mass portion 222 eccentrically formed at an upper end of
the shaft portion 221 in a fan-shape or a shape of an eccentric
circular flange so as to define a plate-shaped extending portion,
and a cam portion 223 formed on an upper surface of the eccentric
mass portion 222 to be eccentric from the shaft portion 221 and
allowing the connecting rod 230 to be rotatably inserted
thereinto.
[0040] The shaft portion 221 may be provided with a first journal
bearing surface 229a and a second journal bearing surface 229b
formed at an outer circumferential surface thereof corresponding to
a journal bearing surface 215 of the shaft bearing hole 212 with a
predetermined interval therebetween. A first oil passage 225a may
be formed in a shaft direction from a lower end of the shaft
portion 221 to the upper end thereof or formed within the defined
area to be slightly inclined in the shaft direction, and a second
oil passage 225b may be formed in the shaft direction from an upper
end of the cam portion 223 to an upper side of the shaft portion
221 with a predetermined depth. The first oil passage 225a and the
second oil passage 225b may not be communicated with each
other.
[0041] A first oil discharge hole 226a for inducing oil toward the
second journal bearing surface 229b of the crank shaft 220 may be
formed at a middle portion of the first oil passage 225a, namely,
at a portion corresponding to a lower portion of the journal
bearing surface 215 of the shaft bearing hole 212. A first oil
groove 226b with a predetermined inclination angle may be spirally
formed from the first oil discharge hole 226a by a predetermined
height, namely, up to almost end of the shaft bearing hole 212. An
oil introduction hole 226c communicating with the second oil
passage 225b may be formed at an end of the first oil groove 226b,
and a second oil discharge hole 226d for inducing oil sucked up via
the second oil passage 225b to an outer circumferential surface may
be formed at a middle of the second oil passage 225b, namely, at a
portion coupled to the connecting rod 230. A second oil groove 226e
having a preset inclination angle may be spirally formed between
the second oil discharge hole 226d and an upper end of the cam
portion 223.
[0042] With such configuration, oil pumped up by the oil feeder O
is sucked up via the first oil passage 225a, and partially guided
into the first oil groove 226b via the first oil discharge hole
226a. The oil guided into the oil groove 226b then flows up along
the first oil groove 226b to sequentially lubricate the first
journal bearing surface 229b and a first journal bearing surface
229a of the crank shaft 220.
[0043] The oil having lubricated the journal bearing surfaces 229a
and 229b is introduced into the second oil passage 225b via the oil
discharge hole 226c, so as to be sucked up again. Part of the oil
flows into the second oil groove 226e via the second oil discharge
hole 226d so as to lubricate the cam portion 223 of the crank shaft
220.
[0044] Here, the crank shaft may be rotated with being inserted
into the shaft bearing hole of the cylinder block, thereby being
supported in a radial direction and simultaneously in a shaft
direction. However, the crank shaft is coupled to the rotor as
mentioned above, so the weight of the crank shaft and the weight of
the rotor increase a load in a shaft direction, which may aggregate
a frictional loss with the cylinder block. Taking this into
account, an approach may be considered in which a point-contactable
bearing, such as a ball bearing, may be installed between a thrust
surface of the cylinder block and a thrust surface of the crank
shaft so as to reduce the frictional loss in the shaft
direction.
[0045] To this end, as shown in FIGS. 1 to 6, the shaft bearing
hole 212, which forms a journal bearing surface so that the crank
shaft 220 is inserted therein so as to be supported in the radial
direction, may be formed at a center of the cylinder block 210. A
thrust surface 213 may be formed at a periphery of an upper end of
the shaft bearing hole 212 and thus a ball bearing assembly
(hereinafter, referred to as ball bearing) for supporting the crank
shaft 220 in the shaft direction can be laid on the thrust surface
213. A bearing locking portion 214 with a preset height may be
formed at an edge of the thrust surface 213 so as to support a
lower washer (or a second washer) 332 to be explained later. Here,
a thrust surface 227 of the crank shaft 220 conformable to the
thrust surface 213 of the cylinder block 210 may be formed to be
flat.
[0046] The bearing locking portion 214 may have a height lower than
a height of the ball bearing 300 in the shaft direction. For
example, an interval between an end surface of the bearing locking
portion 214 and the thrust surface 227 of the crank shaft 220 may
be lower then the shaft-directional height of the ball bearing 300.
Also, the height of the bearing locking portion 214 may not be
greater than a thickness of the lower washer 332 to be explained
later.
[0047] The bearing locking portion 214 may be formed in an annular
shape as shown in FIG. 4; alternatively, it may be formed in any
shape capable of locking the lower washer 332 in the radial
direction, as shown in FIG. 5, for example, in a shape of having at
least three arcuate protrusions along a circumferential direction.
Although not shown, the bearing locking portion 214 may be formed
to be contactable with an inner circumferential surface of the
lower washer 332.
[0048] As another embodiment, although not shown, the bearing
locking portion 214 may be formed at the thrust surface 227 of the
crank shaft 220, namely, a thrust surface 227 of the eccentric mass
portion 222.
[0049] Still referring to FIGS. 1 to 7, each ball bearing 300 may
include a ball cage 310 in an annular shape, at least three balls
320 all rotatably coupled to the ball cage 310, and washers 331 and
332 installed to be contactable with both sides of the balls 320 in
a shaft direction. The washers may not be the essential components
but be installed at any one side.
[0050] The diameter of each ball 320 may be greater than a
thickness of the ball cage 310. The balls 320 may be fixedly
coupled to the ball cage 310.
[0051] The washers 331 and 332 may be classified into an upper
washer (or first washer) 331 and a lower washer (or second washer)
332 based upon the balls 320. The upper and lower washers 331 and
332 may be preferably installed to be supported by the cylinder
block 210 and the crank shaft 220, respectively, in the radial
direction, which allows a smooth bearing action. That is, the upper
washer 331 may be inserted into an outer circumferential surface of
the crank shaft 220 together with the ball cage 310 to be supported
in the radial direction, while the lower washer 332 may be closely
adhered to an inner circumferential surface of the bearing locking
portion 214 provided at the thrust surface 213 of the cylinder
block 210 so as to be locked in the radial direction. The bearing
locking portion 214 may be formed at a periphery of the shaft
bearing hole 212 on the thrust surface 213 of the cylinder block
210 such that its outer circumferential surface contacts an inner
circumferential surface of the lower washer 332.
[0052] As such, the installation of the ball bearing 300 between
the cylinder block 210 and the crank shaft 220 can remarkably
reduce the frictional loss in the shaft direction between the
cylinder block 210 and the crank shaft 220, thereby enhancing
energy efficiency of the compressor. Also, as the ball bearing 300,
especially, the lower washer 332 is locked by the bearing locking
portion 214 of the cylinder block 210 in the radial direction, the
lower washer 332 can always stay at its original position, thereby
allowing a stable operation of the ball bearing 300.
[0053] Another embodiment of a reciprocating compressor according
to the present invention is as follows. That is, in case of
installing such ball bearing between thrust surfaces, oil leakage
in a thrusting direction may be caused due to the characteristic of
the ball bearing. Accordingly, oil guided from the middle of the
crank shaft to the outside of the crank shaft cannot be sucked up
any more, whereby oil may not be supplied to the bearing surfaces
with the connecting rod, especially, a sleeve or not be sucked up
to the upper end. Further, a moment arm may become as long as the
height of the ball bearing, thereby lowering the compressor
efficiency.
[0054] Accordingly, the ball bearing is allowed to be inserted into
the cylinder block or the crank shaft to reduce an interval between
the crank shaft and the cylinder block, so as to minimize the oil
leakage at the middle of the crank shaft due to the oil discharge
hole of the crank shaft being shielded by the journal bearing
surface and simultaneously reduce the length of the moment arm,
thereby enhancing the compressor efficiency.
[0055] To this end, as shown in FIGS. 7 and 8, bearing insertion
grooves 228 in which the ball bearings 300 can be inserted may be
formed. Preferably, a shaft-directional height d of the bearing
insertion groove 228 may not be higher than the shaft-directional
height h of the ball bearing 300. For example, the
shaft-directional height d of bearing insertion groove 228 may not
be lower than the half of the shaft-directional height h of the
ball bearing 300, thereby preventing oil leakage between the thrust
surfaces 213 and 227 of the cylinder block 210 and the crank shaft
220. In other words, the shaft-directional height (i.e., depth) d
of the bearing insertion groove 228, as shown in FIG. 8, may be
preferably formed such that an interval t between the cylinder
block 210 and the crank shaft 220 (i.e., an interval between the
thrust surfaces) in the shaft direction cannot be greater than the
shaft-directional height h of the ball bearing 300.
[0056] Although not shown, the bearing insertion groove 228 may be
formed at the thrust surface 213 of the cylinder block 210 or
formed at both the thrust surface 213 of the cylinder block 210 and
the thrust surface 227 of the crank shaft 220.
[0057] Referring to FIG. 8, as each ball bearing 300 is installed
by being inserted into the bearing insertion groove 228 provided at
the crank shaft 220, the interval t between the cylinder block 210
and the crank shaft 220 may be shorter than the height h of the
ball bearing 300 to thereby shorten the length of the moment arm.
Accordingly, respective forces F2 and F3 applied to the first
journal bearing surface 229a and the second journal bearing surface
229b are decreased, and the frictional losses at the journal
bearing surfaces 229a and 229b are accordingly decreased so much,
thereby enhancing the energy efficiency of the compressor. For
instance, a distance L1 from the center of the cam portion 223 to
the journal bearing surface, namely, to the center of the first
journal bearing surface 229a for supporting a repulsive force
against a gas force applied to the cam portion 223 becomes shorter,
while a distance L2 from the first journal bearing surface 229a to
the second journal bearing surface 229b becomes longer, so that the
forces F2 and F3 respectively applied to the first journal bearing
surface 229a and the second journal bearing surface 229b can be
reduced. In the drawing, F1 denotes a gas force applied to the cam
portion 223, and the gas force may depend on an internal pressure
and a sectional area of a cylinder.
[0058] FIGS. 9 and 10 show graphs showing the changes in the forces
applied to each journal bearing surface respectively in case where
an interval between the cam portion and the first journal bearing
surface is reduced by approximately 5 mm and case where the
interval between the first journal bearing surface and the second
journal bearing surface is reduced by approximately 5 mm in the
configuration that the ball bearings are installed between the
cylinder block and the crank shaft by being inserted into the crank
shaft.
[0059] That is, in case where the ball bearings, as in the related
art, are installed at the facing surfaces between the cylinder
block and the crank shaft to have a preset height, as shown in FIG.
9, a force F1 applied to the cam portion conformable to a gas force
is approximately 600N. In this case, the force F2 applied to the
first journal bearing surface is approximately 1000N and the force
F3 applied to the second journal bearing surface is approximately
300N. However, as shown in the present invention, in case where the
ball bearings are inserted into the cylinder block 210 or the crank
shaft 220, as shown in FIG. 10, when the force F1 applied to the
cam portion 223 is approximately 600N, the force F2 applied to the
first journal bearing surface is approximately 850N and the force
F3 applied to the second journal bearing surface is approximately
150N.
[0060] Consequently, when the bearing insertion groove is formed at
the thrust surface of the crank shaft and the ball bearing is
partially inserted into the bearing insertion groove, approximately
20% of the force applied to the first journal bearing surface is
reduced and approximately 50% of the force applied to the second
journal bearing surface is reduced, so the torque required for a
motor can be reduced, thereby obtaining an effect of enhanced
energy efficiency EER of the compressor.
[0061] In the meantime, the oil introduction hole 226c may
preferably be formed at a position where at least part thereof can
be veiled by the journal bearing surface 215 of the cylinder block
210, thereby minimizing oil guided via the first oil groove 226b
from being leaked, between the cylinder block 210 and the crank
shaft 220. Therefore, the lubrication performance at the cam
portion can be improved so as to further enhance the compressor
efficiency.
[0062] For instance, as shown in FIG. 11, the first oil groove 226b
of the crank shaft 220 may be spirally formed to have a preset
inclination angle, and the spiral angle may be greater or smaller
than about 60.degree., namely, in the range of 45.degree. to
90.degree.. This is intended to form the oil introduction hole 226c
at a position with a narrower angle than a typical spiral angle.
Although not shown, the length of the first oil groove 226b may be
shortened while maintaining the inclination angle thereof as same
as that in the related art so that at least part of the oil
discharge hole can be veiled by the upper portion of the journal
bearing surface.
[0063] The first oil groove 226b may be formed to have a single
inclination angle; but in some cases, it may have a plurality of
inclination angles. This is to allow a large amount of oil to be
stored at a portion of the journal bearing surface where a load is
concentrated, namely, at the first journal bearing surface 229a
adjacent to the cam portion 223.
[0064] For example, as shown in FIG. 11, if the first oil groove
226b has a plurality of inclination angle, a lower groove g1 may be
formed, for example, with an inclination angle .alpha.1 of
45.degree. at a lower side of the first oil groove 226b, namely, up
to a preset height from the first oil discharge hole 226a, and an
upper groove g2 may be formed, for example, with an inclination
angle .alpha. of 30.degree. from the preset height up to the oil
introduction hole 226c.
[0065] Meanwhile, in order for part of oil sucked up along the
first oil groove 226b to stay at an upper end of the first oil
groove 226b, namely, at the periphery of the oil introduction hole
226c, a corner between the journal bearing surface and the thrust
surface of the cylinder block 210 may be cut off so as to define a
chamfer or a round oil pocket 216. Even in this case, as shown in
FIG. 12, in order for part of the oil introduction hole 226c to be
veiled by the journal bearing surface of the cylinder block 210,
the lowermost point of the oil introduction hole 226c may
preferably be formed to be lower than the lowermost point of the
oil pocket 216 at least by a preset height difference .DELTA.h,
namely, the oil introduction hole 216 may be preferably formed such
that the longest distance L3 from the lower surface of the
eccentric mass portion 222 of the crank shaft 220 may be formed not
to be shorter than the shortest distance L4 from the lower surface
to the journal bearing surface 215 of the cylinder block 210. Such
formation can reduce oil leakage between the cylinder block 210 and
the crank shaft 220.
[0066] Hence, as at least part of the oil introduction hole 226c is
formed to be veiled by the journal bearing surface 215 of the
cylinder block 210, even if the ball bearing 300 from which oil may
be leaked is installed at the thrust surface, oil guided via the
first oil groove 226b can be minimized from being leaked between
the cylinder block 210 and the crank shaft 220. Accordingly, the
oil guided via the first oil groove 226b is led toward the second
oil passage 225b via the oil introduction hole 226c, thus allowing
effective lubrication between the cam portion 223 and the
connecting rod 230 and simultaneously smooth suction of oil up to
an upper end of the crank shaft 220, so as to effectively cool the
motor unit 200, resulting in further enhancement of the compressor
efficiency.
[0067] In the meantime, another embodiment of a structure of
supporting a ball bearing of the reciprocating compressor according
to the present invention will be described.
[0068] That is, the previous embodiment has illustrated that the
ball bearings 300 are inserted into the bearing insertion grooves
228 located at the lower surface of the eccentric mass portion 222;
however, this embodiment illustrates that the ball bearing 300 may
be installed at each of the thrust surface of the crank shaft and
the thrust surface of the cylinder block.
[0069] For instance, as shown in FIGS. 13 and 14, bearing insertion
grooves 218 and 228 may be formed at the thrust surface 213 of the
cylinder block 210 and the thrust surface 217 of the crank shaft
220 such that the balls 320 of the ball bearing 300 can be
partially inserted therebetween. The bearing insertion grooves 218
and 228 may be formed to be annular such that the balls 320 of the
ball bearing 300 can be slid in a circumferential direction, and
preferably have a depth less than at least 50% of a diameter of the
ball 320, considering a thickness of the ball cage 310.
[0070] In the configuration of the ball bearing 300, an outer
circumferential surface of each ball 320 may have the same
curvature as that of an inner circumferential surface of the
bearing insertion groove 218 and 228 so as to be linearly
contactable with each other.
[0071] Here, washers 331 and 332 each having an arcuate section, as
shown in FIG. 15, may be located at inner circumferential surfaces
of the bearing insertion grooves 218 and 228. The washers 331 and
332 may preferably be formed of a material with abrasion resistance
superior to that of the cylinder block 210 or the crank shaft
220.
[0072] As shown in FIG. 16, the bearing insertion grooves 218 and
228 each may be formed in a square shape as in the previous
embodiment, and washers 331 and 332, each having an outer
circumferential surface in a square shape and an inner
circumferential surface in an arcuate sectional section with the
same curvature to the ball 320, may be inserted into the bearing
insertion grooves 218 and 228, which renders the washers 331 and
332 to be easily assembled. Also, as shown in FIG. 17, the bearing
insertion grooves 218 and 228 each may be formed in a square shape,
as in the previous embodiment, and washers 331 and 332 each in a
shape of annular plate may be inserted into the bearing insertion
grooves 218 and 228 for installation, which renders the washers 331
and 332 to be easily fabricated.
[0073] Even in case where the bearing insertion grooves 218 and 228
are formed between the cylinder block 210 and the crank shaft 220
so that each ball 320 of the ball bearing 310 can be partially
inserted, the height of the ball bearing 300 may be lowered by a
preset level, as aforementioned, so as to reduce the amount of oil
leaked between the cylinder block 210 and the crank shaft 220 and
simultaneously reduce frictional loss due to a gas force, thereby
enhancing the energy efficiency of the compressor.
[0074] Meanwhile, when the reciprocating compressor according to
the present invention is applied to a refrigerating apparatus, the
performance of the refrigerating apparatus can be improved.
[0075] For example, as shown in FIG. 18, in a refrigerating
apparatus 700 having a refrigerant compression type refrigerating
cycle having a compressor, a condenser, an expansion apparatus and
an evaporator, a reciprocating compressor C, in which
point-contactable bearings such as ball bearings are inserted into
bearing insertion grooves located at the thrust surfaces, as
aforesaid, is installed at a main board 710 for controlling an
overall operation of the refrigerating apparatus within the
refrigerating apparatus 700. The reciprocating compressor C may be
disposed at a position where the oil hole for communicating an oil
groove with an oil passage of a crank shaft is shielded by a
journal bearing surface. Consequently, the refrigerating apparatus
can achieve the effects aforesaid in the description of the
reciprocating compressor and the performance of the refrigerating
apparatus having the reciprocating compressor can be improved.
[0076] Another embodiment of the present invention will now be
described.
[0077] That is, in the previous embodiments, the bearing insertion
groove is formed at the thrust surface of the cylinder block or the
thrust surface of the crank shaft and the bearing assembly is
inserted in the bearing insertion groove, so as to retain a short
distance between the thrust surfaces of the cylinder block and the
crank shaft. However, this embodiment illustrates the following
structure. That is, in case where the bearing assembly is exposedly
installed at the thrust surface of the cylinder block or the thrust
surface of the crank shaft other than by being inserted therein,
instead of minimizing the height of the bearing assembly, the
bearing assembly is allowed to be kept staying at its original
location without being separated between the thrust surfaces,
thereby reducing the frictional loss between the thrust
surfaces.
[0078] For example, if a bearing with a preset height, such as a
ball bearing, is exposedly disposed between the thrust surfaces of
the cylinder block 210 and the crank shaft 220, an interval between
the thrust surfaces becomes wider and additionally the wider
interval renders oil sucked up via the first oil groove 226b flow
out toward the thrust surfaces without flowing toward the oil
introduction hole 226c, thereby lowering the compressor efficiency.
Therefore, when installing the ball bearing between the cylinder
block and the crank shaft, the diameter of each ball of the ball
bearing can be fabricated as small as possible, to prevent the
interval between the thrust surfaces from being excessively
increased due to the installation of the ball bearing.
[0079] However, if the diameter of the ball bearing becomes too
short and the ball bearing moves in a radial direction, the balls
of the ball bearing are slipped out of the oil pocket between the
thrust surface and the journal bearing surface of the cylinder
block, thereby possibly causing the ball bearing not to function as
a bearing.
[0080] To consider this problem, as shown in FIGS. 19 and 20, a
bearing supporting portion 224 for supporting the ball bearing 300
in a radial direction should be formed at an outer circumferential
surface of the crank shaft 220 facing the inner circumferential
surface of the ball bearing 300, or, although not shown, the ball
cage 310 of the ball bearing 300 should extend in its inner
circumferential surface. For the latter, if the ball cage 310 is
thinly fabricated, as the width thereof becomes wider, the
intensity of the ball cage 310 becomes weaker, thereby increasing
the chance of damage or deformation of the ball cage 310.
Accordingly, each ball 320 coupled to the ball cage 310 may not
smoothly rotate, thus drastically lowering the bearing performance.
Therefore, in order to render the balls 320 stay at proper
positions, namely, position not to be slipped out of the oil
pockets 216 without widening the width of the ball cage 310, the
bearing supporting portion 224, as similar to the former, may
preferably be formed at the outer circumferential surface of the
crank shaft 220. Further, in any manner of increasing the intensity
of the ball cage 310, it may also be possible to widen the width of
the ball cage 310.
[0081] FIG. 21 shows an example in which the bearing supporting
portion is protruded from the outer circumferential surface of the
crank shaft 220 to have a preset thickness in a stepped state. As
shown in FIG. 21, the bearing supporting portion 224 may extend
between the first journal bearing surface 229a and the thrust
surface, namely, from the thrust surface in a shaft direction, so
as to be in the stepped state. The bearing supporting portion 224
may preferably be formed such that a distance B from a shaft center
of the crank shaft 220 to the center of the ball 320 may not be
shorter than a distance CB1 from the shaft center of the crank
shaft 220 to the lowermost point of the oil pocket 216, more
particularly, a distance D from the shaft center of the crank shaft
220 to an outer circumferential surface of the bearing supporting
portion 224. Such formation can prevent the ball 320 from being
slipped out of the oil pocket 216.
[0082] The bearing supporting portion 224 may preferably be formed
to have a length long enough that the ball cage 310 cannot be
slipped out of a lower side of the bearing supporting portion 224,
namely, toward the first journal bearing surface 229a. To this end,
a height H1 of the bearing supporting portion 224 may be higher
than a distance HCU from a lower surface of the eccentric mass
portion 222 to an upper surface of the ball cage 310. That is, the
height of the bearing supporting portion 224 may not be lower than
the distance HCU from the thrust surface of the eccentric mass
portion 222 to the upper surface of the ball cage 310 and not lower
than a distance HCL from the thrust surface of the eccentric
portion 222 to the lower surface of the ball cage 310, thereby
preventing the ball cage 310 from being slipped out of the lower
side of the bearing supporting portion 224, namely, out of the oil
pocket 216.
[0083] Washers 331 and 332 for supporting the balls 320 may further
be installed at both sides of the ball bearing 310 in the shaft
direction. However, the washers 331 and 332 may not be essential
components; alternatively, one washer may be installed at one
side.
[0084] The washers 331 and 332 may be classified into an upper
washer (or first washer) 331 and a lower washer 332 based upon the
balls 320. The upper and lower washers 331 and 332 may be
preferably installed to be supported by the cylinder block 210 and
the crank shaft 220, respectively, in the radial direction, which
allows a smooth bearing action. The ball cage 310 may be disposed,
as aforesaid, such that its inner circumferential surface can be
supported by the crank shaft 220. The lower washer 332 may have an
outer circumferential surface supported by the bearing locking
portion 214 of the cylinder block 210. In this case, a height H2 of
the bearing locking portion 214 may be lower than a distance HBL2
from a bottom surface of the thrust surface 213 to the lower
surface of the ball cage 310, which allows a stable bearing action
of the outer circumferential surface of the ball cage 310 due to
unlocked state thereof from the cylinder block 210.
[0085] Here, the thickness of each washer 331 and 332 may not
preferably be greater than the diameter 320, thereby maintaining a
preset level of diameter of the ball 320. For instance, the
diameter of the ball 320 may be formed within the range of 1.5-10
times the thickness of the washers 331 and 332
(1.5-10.times.thickness), thereby maintaining the intensity of the
ball 320 in the shaft direction.
[0086] In the meantime, as aforementioned, the bearing supporting
portion 224 may be integrally formed with the crank shaft 220; in
some cases, it may be formed in a form of bush so as to be
assembled to the crank shaft 220 by bolts or rivets. Even in this
case, the size (configuration) of the bearing supporting portion
224 should be the same to the aforesaid embodiments, so the
detailed description thereof will be omitted.
[0087] As another embodiment, the ball bearing according to the
present invention may have the outer circumferential surface
supported by the cylinder block 210 unlike the aforesaid
embodiments. To this end, as shown in FIG. 22, the height H2 of the
bearing locking portion 214 may be formed higher and the outer
circumferential surface of the ball cage 310 is allowed to be
supported by the inner circumferential surface of the bearing
locking portion 214 in the radial direction.
[0088] Even in this case, the inner circumferential surface of the
ball cage 310 should not be supported by the outer circumferential
surface of the crank shaft 220. If the outer circumferential
surface of the ball cage 310 is supported by the cylinder block 210
and the inner circumferential surface thereof is supported by the
crank shaft 220, an excessive load is applied to the ball bearing
300 in the radial direction, thereby worrying about the damage or
destroy of the ball bearing 300.
[0089] Not only when the inner circumferential surface of the ball
cage 310 of the ball bearing 300 is supported by the outer
circumferential surface of the crank shaft 220, namely, by the
outer circumferential surface of the bearing supporting portion 224
of the crank shaft 220, but also when the outer circumferential
surface of the ball cage 310 is supported by the inner
circumferential surface of the bearing locking portion 214 of the
cylinder block 210, a preset interval may preferably be maintained
between the ball cage 310 and the surfaces supporting the ball cage
310, thus increasing reliability of the ball bearing 300.
[0090] Here, the configuration of the bearing locking portion for
allowing the ball cage to be supported by the cylinder block can be
obviously understood upon considering the aforesaid example,
namely, being supported by the crank shaft. As one example, the
height H2 of the bearing locking portion 214 should be higher than
at least the height HCL1 from the thrust surface 213 to the lower
surface of the ball cage 310.
[0091] The reciprocating compressor according to the present
invention may have the following operational effects.
[0092] That is, the installation of the ball bearing 300 between
the thrust surfaces of the cylinder block 310 and the crank shaft
320 can remarkably decrease a frictional loss between the thrust
surfaces, thereby improving the energy efficiency of the
compressor.
[0093] As the bearing supporting portion 224 is formed at the crank
shaft 220 so as to reduce the diameter of the ball 320 of the ball
bearing 300 and simultaneously support the ball cage 310 in the
radial direction, the ball bearing 300 can always be located at its
original position, thereby preventing in advance the lowering of
the bearing performance. Also, the reduced diameter of the ball 320
may prevent an excessive increase in the interval between the
thrust surfaces, thereby preventing an excessive lengthening of the
length of the moment arm, resulting in preventing an increase in
forces applied respectively to the first journal bearing surface
229a and the second journal bearing surface 229b. Hence, the
frictional loss at the journal bearing surfaces 229a and 229b can
be reduced, thereby enhancing the energy efficiency of the
compressor.
[0094] In the meantime, if the reciprocating compressor according
to the present invention is applied to a refrigerating apparatus,
as mentioned in the previous embodiment, the performance of the
refrigerating apparatus can be improved.
INDUSTRIAL APPLICABILITY
[0095] In association with the reciprocating compressor and the
refrigerating apparatus having the same according to the present
invention, a single type reciprocating compressor having a single
cylinder has been illustrated; however, in some cases, the present
invention can also be applied to a multi-type reciprocating
compressor having many cylinders and a refrigerating apparatus
having the same.
* * * * *