U.S. patent application number 10/865001 was filed with the patent office on 2004-12-16 for piston type compressor.
Invention is credited to Inoue, Yoshinori, Kawachi, Shigeki, Kawamura, Hisato, Mochizuki, Kenji, Takahata, Junichi.
Application Number | 20040253118 10/865001 |
Document ID | / |
Family ID | 33296888 |
Filed Date | 2004-12-16 |
United States Patent
Application |
20040253118 |
Kind Code |
A1 |
Inoue, Yoshinori ; et
al. |
December 16, 2004 |
Piston type compressor
Abstract
A piston type compressor includes a suction valve mechanism. The
suction valve mechanism includes a rotary valve coupled to a rotary
shaft. A valve timing adjusting apparatus is capable of changing a
relative rotational phase, which is a rotational phase of the
rotary valve relative to the rotary shaft. Therefore, the
compressor is capable of adjusting the valve timing of the rotary
valve and has a reduced size in the axial direction.
Inventors: |
Inoue, Yoshinori;
(Kariya-shi, JP) ; Takahata, Junichi; (Kariya-shi,
JP) ; Kawamura, Hisato; (Kariya-shi, JP) ;
Mochizuki, Kenji; (Kariya-shi, JP) ; Kawachi,
Shigeki; (Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 WORLD FINANCIAL CENTER
NEW YORK
NY
10281-2101
US
|
Family ID: |
33296888 |
Appl. No.: |
10/865001 |
Filed: |
June 10, 2004 |
Current U.S.
Class: |
417/222.1 ;
417/222.2; 417/269 |
Current CPC
Class: |
F04B 27/14 20130101 |
Class at
Publication: |
417/222.1 ;
417/222.2; 417/269 |
International
Class: |
F04B 001/26; F04B
001/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 12, 2003 |
JP |
2003-168392 |
Claims
1. A piston type compressor, comprising: a rotary shaft; a suction
pressure zone; a compression chamber; a gas passage extending from
the suction pressure zone to the compression chamber; a piston
defining the compression chamber, wherein the piston reciprocates
as the rotary shaft rotates, and as the piston reciprocates, gas is
drawn into the compression chamber from the suction pressure zone
through the gas passage, and the drawn gas is compressed in the
compression chamber; a suction valve mechanism that selectively
opens and closes the gas passage, the suction valve mechanism
including a rotary valve coupled to the rotary shaft, wherein the
rotary valve rotates in response to rotation of the rotary shaft,
thereby selectively opening and closing the gas passage; and a
valve timing adjusting apparatus capable of changing a relative
rotational phase, which is a rotational phase of the rotary valve
relative to the rotary shaft.
2. The compressor according to claim 1, wherein the adjusting
apparatus determines the relative rotation phase according to a
rotation speed of the rotary shaft.
3. The compressor according to claim 1, wherein the adjusting
apparatus rotates according to the rotation speed of the rotary
shaft, and determines the relative rotation phase according to a
centrifugal force acting on the adjusting apparatus.
4. The compressor according to claim 2, wherein, when the rotation
speed of the rotary shaft is increased, the adjusting apparatus
changes the relative rotational phase to delay timing at which
suction of gas from the suction pressure zone to the compression
chamber is ended, and wherein, when the rotation speed of the
rotary shaft is decreased, the adjusting apparatus changes the
relative rotational phase to advance the suction end timing.
5. The compressor according to claim 2, wherein, when the rotation
speed of the rotary shaft is increased, the adjusting apparatus
changes the relative rotational phase to delay timing at which
suction of gas from the suction pressure zone to the compression
chamber is started, and wherein, when the rotation speed of the
rotary shaft is decreased, the adjusting apparatus changes the
relative rotational phase to advance the suction start timing.
6. The compressor according to claim 2, wherein the rotary valve is
arranged coaxial with the rotary shaft and engaged with the rotary
shaft such that the rotary valve rotates relative to the rotary
shaft, wherein the adjusting apparatus has a power transmitting
member for transmitting power from the rotary shaft to the rotary
valve, wherein the power transmitting member is displaceably
located between the rotary shaft and the rotary valve, wherein the
relative rotational phase is changed according to the position of
the power transmitting member, and wherein the adjusting apparatus
has a position determining device that determines the position of
the power transmitting member according to the rotation speed of
the rotary shaft.
7. The compressor according to claim 6, wherein the power
transmitting member is a spherical body.
8. The compressor according to claim 6, wherein the power
transmitting member is located at an eccentric position relative to
the rotary shaft and is displaceable in a radial direction of the
rotary shaft, wherein the position determining device has an urging
member for urging the power transmitting member radially inward
with respect to the rotary shaft, and wherein the position of the
power transmitting member is determined according to a centrifugal
force that acts on the power transmitting member as the rotary
shaft rotates and an urging force applied to the power transmitting
member by the urging member.
9. The compressor according to claim 6, wherein the rotary shaft
has a power transmitting surface that transmits power to the power
transmitting member, the rotary valve has a power receiving surface
that receives power from the power transmitting member, and wherein
the distance with respect to the rotation direction of the rotary
shaft between the power transmitting surface and the power
receiving surface is reduced toward the axis of the rotary
shaft.
10. The compressor according to claim 6, wherein one of the rotary
shaft and the rotary valve has an engaging projection that extends
in the axial direction of the rotary shaft, and the other has an
engaging recess to which the engaging projection is fitted, and
wherein the power transmitting member and the position determining
device are located between the engaging projection and the engaging
recess.
11. The compressor according to claim 6, wherein the rotary shaft
and the rotary valve have an engaging mechanism that defines a
relative rotational phase that is most advance relative to the
rotary shaft.
12. The compressor according to claim 6, wherein the position
determining device includes: a rotation speed sensor for detecting
the rotation speed of the rotary shaft; an urging force applying
device for applying an urging force to the power transmitting
member, wherein the urging force applying device changes the urging
force based on a driving signal from the outside, thereby
determining the position of the power transmitting member; and a
control device that adjusts the driving signal supplied to the
urging force applying device based on detected information from the
rotation speed sensor.
13. The compressor according to claim 12, wherein the power
transmitting member is made of metal, the urging force applying
device includes an electromagnet, and wherein the electromagnet
generates an electromagnetic attractive force for urging the power
transmitting member.
14. The compressor according to claim 1, wherein the rotary valve
is arranged coaxial with the rotary shaft and engaged with the
rotary shaft such that the rotary valve rotates relative to the
rotary shaft, wherein the adjusting apparatus has a power
transmitting member for transmitting power from the rotary shaft to
the rotary valve, wherein the power transmitting member is
displaceably located between the rotary shaft and the rotary valve,
wherein the relative rotational phase is changed according to the
position of the power transmitting member, and wherein the
adjusting apparatus has a position determining device that
determines the position of the power transmitting member.
15. The compressor according to claim 14, wherein the position
determining device includes: an urging force applying device for
applying an urging force to the power transmitting member, wherein
the urging force applying device changes the urging force based on
a driving signal from the outside, thereby determining the position
of the power transmitting member; and a control device that adjusts
the driving signal supplied to the urging force applying
device.
16. A piston type compressor, comprising: a rotary shaft having a
power transmitting surface; a suction pressure zone; a compression
chamber; a gas passage extending from the suction pressure zone to
the compression chamber; a piston defining the compression chamber,
wherein the piston reciprocates as the rotary shaft rotates, and as
the piston reciprocates, gas is drawn into the compression chamber
from the suction pressure zone through the gas passage, and the
drawn gas is compressed in the compression chamber; a rotary valve
coupled to the rotary shaft, wherein the rotary valve rotates in
response to rotation of the rotary shaft, thereby selectively
opening and closing the gas passage, the rotary valve is arranged
coaxial with the rotary shaft and engaged with the rotary shaft
such that the rotary valve rotates relative to the rotary shaft,
the rotary valve having a power receiving surface; a power
transmitting member located between the power transmitting surface
and the power receiving surface, wherein the power transmitting
member transmits power from the power transmitting surface to the
power receiving surface, wherein the power transmitting member is
displaced in a radial direction of the rotary shaft by a
centrifugal force that is applied to the power transmitting member
as the rotary shaft rotates, and wherein a relative rotational
phase, which is a rotational phase of the rotary valve relative to
the rotary shaft, is changed according to the position of the power
transmitting member; and an urging member for urging the power
transmitting member radially inward with respect to the rotary
shaft.
17. The compressor according to claim 16, wherein, when the
rotation speed of the rotary shaft is increased, the power
transmitting member is displaced to delay timing at which suction
of gas from the suction pressure zone to the compression chamber is
ended, and wherein, when the rotation speed of the rotary shaft is
decreased, the power transmitting member is displaced to advance
the suction end timing.
18. The compressor according to claim 16, wherein the distance with
respect to the rotation direction of the rotary shaft between the
power transmitting surface and the power receiving surface is
reduced toward the axis of the rotary shaft.
19. The compressor according to claim 16, further comprising: an
urging force applying device for applying an urging force to the
power transmitting member, wherein the urging force applying device
changes the urging force based on a driving signal from the
outside, thereby determining the position of the power transmitting
member; and a control device that adjusts the driving signal
supplied to the urging force applying device.
20. The compressor according to claim 19, further comprising a
rotation speed sensor for detecting the rotation speed of the
rotary shaft, and wherein the control device adjusts the driving
signal based on detected information from the rotation speed
sensor.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a piston type compressor in
which rotation of a rotary shaft is converted into reciprocation of
pistons, thereby drawing gas from a suction pressure zone to
compression chambers through suction valve mechanism, and
compressing the gas in the compression chambers.
[0002] Some piston type compressors have a rotary valve as a
suction valve mechanism. A rotary valve is coupled to a rotary
shaft and rotates in response to rotation of the rotary shaft,
thereby selectively opening and closing a gas passage between
compression chambers and a suction pressure zone. In a piston type
compressor having a rotary valve as a suction valve mechanism, the
timing at which a gas passage between a suction pressure zone and a
compression chamber is closed (suction end timing) is determined by
the position of a valve hole on the outer circumference of the
rotary valve, which valve hole guides gas from the suction pressure
zone to compression chambers.
[0003] However, the optimum suction end timing varies according to
the rotation speed of the piston type compressor, that is, the
rotation speed of the rotary shaft. Therefore, when a rotary valve
is used as a suction valve mechanism, the actual suction end timing
cannot be easily controlled to be in constant synchronization with
the optimum suction end timing.
[0004] For example, when the speed of the rotary shaft is
increased, the velocity of gas is also increased and the inertial
force of the gas is increased, accordingly. Therefore, even if a
piston is at or in the vicinity of the bottom dead center, gas is
drawn into the compression chamber by the inertial force, which
expectedly increases the compression efficiency. However, if the
suction end timing of the rotary valve is optimized for a lower
speed of the rotary shaft, the actual suction end timing is too
advanced compared to the optimum suction end timing when the rotary
shaft speed is high. In this case, the effect of the suction by
inertial force cannot be expected.
[0005] On the other hand, when the rotary shaft speed is decreased,
effective suction of gas by inertia is not expected. Therefore, if
the rotary valve is open until the piston reaches the bottom dead
center, gas can flow back to the suction pressure zone from the
compression chamber. In this manner, if the suction end timing is
optimized for a higher rotary shaft speed, backflow of gas from the
compression chamber to the suction pressure zone reduces the
compression efficiency when the rotary shaft speed is low.
[0006] The drawback that the actual valve timing of a rotary valve
is not in synchronization with optimum valve timing presents not
only with respect to the suction end timing, but also with respect
to the timing at which a gas passage between the suction pressure
zone and the compression chamber is opened (suction start
timing).
[0007] Conventionally, to eliminate the drawback that the suction
end timing of a rotary valve is displaced from an optimum timing, a
rotary valve having two or more axially separated valve holes
corresponding to two or more suction end timings has been proposed
(for example, Japanese Laid-Open Patent Publication No. 6-117363).
According to the speed of the rotary shaft, one of the valve holes
that corresponds to the optimum suction end timing at the time is
selected.
[0008] However, according to Japanese Laid-Open Patent Publication
No. 6-117363, the rotary valve needs to be moved in the axial
direction of the rotary shaft relative to the rotary shaft when
selecting one of the valve holes that corresponds to the current
optimum suction end timing. That is, a room that allows the rotary
valve to be moved in the axial direction is required. This
increases the piston type compression in the axial direction.
SUMMARY OF THE INVENTION
[0009] Accordingly, it is an objective of the present invention to
provide a piston type compressor that is capable of adjusting the
valve timing of a rotary valve and has a reduced size in the axial
direction.
[0010] To achieve the above objective, the present invention
provides a piston type compressor. The compressor includes a rotary
shaft, a suction pressure zone, a compression chamber, a gas
passage extending from the suction pressure zone to the compression
chamber, and a piston defining the compression chamber. The piston
reciprocates as the rotary shaft rotates, and as the piston
reciprocates, gas is drawn into the compression chamber from the
suction pressure zone through the gas passage, and the drawn gas is
compressed in the compression chamber. A suction valve mechanism
selectively opens and closes the gas passage. The suction valve
mechanism includes a rotary valve coupled to the rotary shaft. The
rotary valve rotates in response to rotation of the rotary shaft,
thereby selectively opening and closing the gas passage. A valve
timing adjusting apparatus is capable of changing a relative
rotational phase, which is a rotational phase of the rotary valve
relative to the rotary shaft.
[0011] Other aspects and advantages of the invention will become
apparent from the following description, taken in conjunction with
the accompanying drawings, illustrating by way of example the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The invention, together with objects and advantages thereof,
may best be understood by reference to the following description of
the presently preferred embodiments together with the accompanying
drawings in which:
[0013] FIG. 1 is a cross-sectional view illustrating a swash plate
type variable displacement compressor according to one embodiment
of the present invention;
[0014] FIG. 2 is an enlarged partial cross-sectional view of the
compressor shown in FIG. 1;
[0015] FIG. 3 is a cross-sectional view taken along line III--III
in FIG. 2;
[0016] FIG. 4 is a cross-sectional view taken along line IV--IV in
FIG. 2;
[0017] FIG. 5 is a cross-sectional view illustrating the compressor
shown in FIG. 1 when the compressor is operating at a high speed;
and
[0018] FIG. 6 is a cross-sectional view illustrating a modification
according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] In the drawings, like numerals are used for like elements
throughout.
[0020] A preferred embodiment of the present invention will now be
described.
[0021] First, a piston type compressor, which functions as a swash
plate type variable displacement compressor for compressing
refrigerant, will be described. The compressor is used in a vehicle
air conditioner.
[0022] As shown in FIG. 1, the compressor 10 includes a cylinder
block 11, a front housing member 12, a valve assembly 13, and a
rear housing member 14. The front housing member 12 is secured to
the front end of the cylinder block 11. The rear housing member 14
is secured to the rear end of the cylinder block 11 with the valve
assembly 13 in between. The cylinder block 11, the front housing
member 12, and the rear housing member 14 form a housing of the
compressor 10. The left end of the compressor 10 in FIG. 1 is
defined as the front of the compressor 10, and the right end is
defined as the rear of the compressor 10.
[0023] The cylinder block 11 and the front housing member 12 define
a crank chamber 15 in between. A rotary shaft 16 extends through
the crank chamber 15 and is rotatably supported by the front
housing member 12 and the cylinder block 11. The rotary shaft 16 is
coupled to an external drive source, which is an engine Eg in this
embodiment. The rotary shaft 16 is rotated by power supplied by the
engine Eg. Therefore, the speed of the rotary shaft 16 is varied
according to the speed of the engine Eg.
[0024] A lug plate 20 is coupled to the rotary shaft 16 and is
located in the crank chamber 15. The lug plate 20 rotates
integrally with the rotary shaft 16. A swash plate 21 is
accommodated in the crank chamber 15. The swash plate 21 slides
along and inclines with respect to the rotary shaft 16. A hinge
mechanism 22 is arranged between the lug plate 20 and the swash
plate 21. The lug plate 20 permits the swash plate 21 to rotate
integrally with the rotary shaft 16 and to incline with respect to
the rotary shaft 16 while sliding along the rotation axis L of the
rotary shaft 16.
[0025] As shown in FIGS. 1 and 3, a plurality of cylinder bores 23,
the number of which is five in this embodiment (only one is shown
in FIG. 1) are formed through the cylinder block 11. The cylinder
bores 23 surrounds the rear end of the rotary shaft 16 and are
spaced from one another by a predetermined angular interval. A
single headed piston 24 is accommodated in each cylinder bore 23.
The piston 24 reciprocates inside the cylinder bore 23.
[0026] As shown in FIG. 1, the front and rear openings of each
cylinder bore 23 are closed by the associated piston 24 and the
valve assembly 13. A compression chamber 26 is defined in each
cylinder bore 23. The volume of the compression chamber 26 changes
according to the reciprocation of the corresponding piston 24. Each
piston 24 is coupled to the peripheral portion of the swash plate
21 by a pair of shoes 25. The shoes 25 convert rotation of the
swash plate 21, which rotates with the rotary shaft 16, into
reciprocation of the pistons 24.
[0027] A suction chamber 27 and a discharge chamber 28 are defined
in the rear housing member 14. The suction chamber 27 functions as
a suction pressure zone. The suction chamber 27 is defined in a
center portion of the rear housing member 14. The discharge chamber
28 is defined to surround the suction chamber 27. The suction
chamber 27 is connected to an external pipe connected to a low
pressure heat exchanger (not shown) of an external refrigerant
circuit. The discharge chamber 28 is connected to an external pipe
connected to a high pressure heat exchanger (not shown) of the
external refrigerant circuit. The external refrigerant circuit and
the compressor 10 form a refrigerant circuit (refrigerant cycle) of
the vehicle air conditioner.
[0028] As each piston 24 moves from the top dead center to the
bottom dead center, refrigerant gas in the suction chamber 27 is
drawn into the corresponding compression chamber 26 through a
suction valve mechanism 55 provided in the cylinder block 11.
Refrigerant gas drawn into the compression chamber 26 is compressed
to a predetermined pressure as the piston 24 is moved from the
bottom dead center to the top dead center. Then, the gas is
discharged to the discharge chamber 28 through one of discharge
ports 29 while flexing one of discharge valve flaps 30, which
discharge ports 29 and discharge valve flaps 30 are provided in the
valve assembly 13.
[0029] A bleed passage 31, a supply passage 32, and a displacement
control valve 33 are provided in the housing of the compressor 10.
The bleed passage 31 connects the crank chamber 15 with the suction
chamber 27. The bleed passage 31 includes an axial passage 34
formed along the axis L of the rotary shaft 16. An inlet 34a of the
axial passage 34 is opened to the crank chamber 15 in the vicinity
of the lug plate 20. An outlet 34b of the axial passage 34 is
opened at the rear end face of the rotary shaft 16. The supply
passage 32 connects the crank chamber 15 with the discharge chamber
28. The supply passage 32 is regulated by the displacement control
valve 33, which is a conventional electromagnetic valve.
[0030] The opening degree of the control valve 33 is adjusted to
control the balance between the flow rate of highly pressurized gas
supplied to the crank chamber 15 through the supply passage 32 and
the flow rate of gas conducted out of the crank chamber 15 through
the bleed passage 31. The pressure in the crank chamber 15 is thus
adjusted. As the pressure in the crank chamber 15 varies, the
difference between the pressure in the crank chamber 15 and the
pressure in the compression chambers 26 with the pistons 24 in
between is changed. This changes the inclination angle of the swash
plate 21. Accordingly, the stroke of each piston 24, or the
compressor displacement, is controlled.
[0031] For example, when the pressure in the crank chamber 15 is
lowered as the opening degree of the displacement control valve 33
is reduced, the inclination angle of the swash plate 21 is
increased. This lengthens the stroke of each piston 24 and the
compressor displacement is increased, accordingly. In contrast,
when the pressure in the crank chamber 15 is increased as the
opening degree of the displacement control valve 33 is increased,
the inclination angle of the swash plate 21 is decreased. This
shortens the stroke of each piston 24 and the compressor
displacement is decreased, accordingly.
[0032] The suction valve mechanism 55 will now be described.
[0033] As shown in FIGS. 2 and 3, a cylindrical accommodation hole
17 is formed in the housing of the compressor 10. The accommodation
hole 17 is located in a center portion of the cylinder block 11
that is surrounded by the cylinder bores 23. A boss portion 11a is
formed at the rear end of the cylinder block 11. The boss portion
11a projects through the valve assembly 13 from a portion about the
opening of the accommodation hole 17. Part of the boss portion 11a
is located in the center portion of the rear housing member 14.
Accordingly, the accommodation hole 17 and the suction chamber 27
are continuously arranged along the direction of the axis L. A
plurality of introducing passages 18, the number of which is five
in this embodiment (only one is shown in FIG. 2), are formed in the
cylinder block 11. The introducing passages 18 extend radially from
the axis L. Each compression chamber 26 is connected to the
accommodation hole 17 by one of the introducing passages 18.
[0034] A rotary valve 35 is rotatably accommodated in the
accommodation hole 17. The rotary valve 35 substantially has a
hollow cylindrical shape with a bottom. The bottom is located at
the front end of the rotary valve 35. A front portion of the rotary
valve 35 has a small diameter (small diameter portion 35a). A valve
receiving hole 16a is formed at the rear end of the rotary shaft
16, which faces the accommodation hole 17. The small diameter
portion 35a of the rotary valve 35 is fitted in the valve receiving
hole 16a of the rotary shaft 16. Accordingly, the rotary valve 35
and the rotary shaft 16 are aligned along the common axis L. The
rotary valve 35 and the rotary shaft 16 are permitted to be
displaced relative to each other in the rotation direction of the
rotary shaft 16 about the axis L.
[0035] A spherical body, which is a steel ball 63, is located at an
engaging sections of the rotary shaft 16 and the rotary valve 35.
The rotary valve 35 is coupled to the rotary shaft 16 with the ball
63 in between, which permits the rotary valve 35 to rotate in
response to rotation of the rotary shaft 16, that is, to
reciprocation of the pistons 24. The rotary valve 35 has a large
diameter portion 35b. A circumferential surface 35c of the large
diameter portion 35b and an inner circumferential surface 17a of
the accommodation hole 17 form sliding bearing surfaces that
rotatably support the rear end portion of the rotary shaft 16.
[0036] The inner circumferential surface 17a of the accommodation
hole 17 and the circumferential surface 35c of the large diameter
portion 35b of the rotary valve 35 closely and slidably contact
each other. A communication hole 35d is formed through a front end
portion of the rotary valve 35. The communication hole 35d extends
in a front-rear direction. An inside space of the rotary valve 35,
which is an introduction chamber 36, is connected to the axial
passage 34 in the rotary shaft 16 (the outlet 34b) by the
communication hole 35d. The introduction chamber 36 communicates
with the suction chamber 27. The communication hole 35d and the
introduction chamber 36 form part of the bleed passage 31.
[0037] A suction guide hole 37 is formed in the circumferential
wall of the rotary valve 35. The suction guide hole 37 extends in a
predetermined circumferential section and functions as a valve hole
that always communicates with the introduction chamber 36. When
each piston 24 is in a suction stroke, the suction guide hole 37 in
the rotary valve 35 communicates with the associated introducing
passage 18 in the cylinder block 11. Therefore, refrigerant gas in
the suction chamber 27 is drawn into each compression chamber 26
via the introduction chamber 36 in the rotary valve 35, the suction
guide hole 37, and the associated introducing passage 18 formed in
the cylinder block 11 in order. The introduction chamber 36, the
suction guide hole 37, and the associated introducing passage 18
form a gas passage, which extends from the suction pressure zone to
the associated compression chamber 26.
[0038] At the end of the suction stroke of each piston 24, the
suction guide hole 37 is completely displaced from the associated
introducing passage 18. Accordingly, suction of refrigerant gas
from the introduction chamber 36 to the compression chamber 26 is
stopped. When the piston 24 shifts to compression-discharge stroke,
the outer circumferential surface 35c of the large diameter portion
35b of the rotary valve 35 maintains the associated introducing
passage 18 disconnected from the introduction chamber 36. This
prevents compression of refrigerant gas and discharge of compressed
gas to the discharge chamber 28 from being hindered.
[0039] A valve timing adjusting apparatus 60 will now be described.
The valve timing adjusting apparatus 60 changes the relative
rotational phase of the rotary valve 35 to the rotary shaft 16,
that is, the valve timing of the rotary valve 35 (in this
embodiment, suction end timing).
[0040] As shown in FIGS. 2, 4, and 5, an accommodating recess 61 is
formed in the inner circumference 16b of the valve receiving hole
16a of the rotary shaft 16. The accommodating recess 61 is
cylindrical and extends radially outward from an opening in the
inner circumference 16b of the valve receiving hole 16a. The ball
63 is accommodated in the accommodating recess 61 to be movable in
the extending direction of the recess 61, that is, along a radial
direction of the rotary shaft 16. Therefore, the ball 63 is located
at an eccentric position relative to the rotary shaft 16. An urging
member, which is an urging spring 64, is accommodated in the
accommodating recess 61. The urging spring 64 is a coil spring. The
urging spring 64 urges the ball 63 radially inward toward the axis
L.
[0041] As shown in FIGS. 4 and 5, a guide projection 65 is formed
on the inner circumference 16b of the valve receiving hole 16a in
an area that is rearward of the opening of the accommodating recess
61 with respect to the rotational direction of the rotary shaft 16.
In other words, the projection 65 has a phase delayed relative to
the phase of the recess 61 and is located rearward of the recess 61
in the clockwise direction. A surface 65a of the guide projection
65 at the accommodating recess 61 is formed continuously with a
part (an area 61a at the trailing side in the rotational direction)
of the inner wall of the accommodating recess 61, and guides the
movement of the ball 63. The surface 65a of the guide projection 65
corresponding to the accommodating recess 61 and the area 61a of
the inner surface of the accommodating recess 61 function as power
transmitting surfaces 61a, 65a that transmit rotational force of
the rotary shaft 16 to the rotary valve 35 with the ball 63.
[0042] In the rotary valve 35, a groove 62 is formed in a part of
the outer circumference 35e of the small diameter portion 35a. The
groove 62 extends along the circumferential direction and receives
the guide projection 65 of the rotary shaft 16. A flat power
receiving surface 62a and a flat rear surface 62b are formed in the
bottom of the groove 62. The power receiving surface 62a is located
at an advancing side in the rotational direction and faces toward a
direction opposite the rotational direction. The rear surface 62b
is located at the trailing side in the rotational direction and
faces the rotational direction. The power receiving surface 62a and
the rear surface 62b are inclined relative to each other so that
the joint of the surfaces 62a, 62b is dented toward the axis L.
[0043] The ball 63 is located between the power transmitting
surfaces 61a, 65a of the rotary shaft 16 and the power receiving
surface 62a of the rotary valve 35. Rotational force that is
transmitted from the power transmitting surfaces 61a, 65a of the
rotary shaft 16 to the ball 63 is then transmitted to the rotary
valve 35 through the power receiving surface 62a. Accordingly, the
rotary valve 35 is rotated. The power transmission from the rotary
shaft 16 to the rotary valve 35 with the ball 63 is performed by
tightly holding the ball 63 between the power transmitting surfaces
61a, 65a and the power receiving surface 62a. The distance between
the power transmitting surfaces 61a, 65a and the power receiving
surface 62a, which tightly hold the ball 63, or perform power
transmission (torque transmission) with the ball 63, is varied
according to the position of the ball 63 with respect to the radial
direction of the rotary shaft 16.
[0044] For example, as shown in FIG. 4, when the ball 63 is moved
radially inward from a certain position, the distance between the
power transmitting surfaces 61a, 65a and the power receiving
surface 62a is increased while the surfaces 61a, 65a and 62a hold
the ball 63. To increase the distance between the power
transmitting surfaces 61a, 65a and the power receiving surface 62a,
the rotary valve 35 needs to be shifted relative to the rotary
shaft 16 in the rotational direction of the rotary shaft 16.
Shifting the rotary valve 35 relative to the rotary shaft 16 in the
rotational direction, that is, advancing the relative rotational
phase of the rotary valve 35 to the rotary shaft 16, advances the
suction end timing of the rotary valve 35.
[0045] The rear surface 62b of the groove 62 of the rotary valve 35
and a surface of the guide projection 65 of the rotary shaft. 16
that faces the rear surface 62b function as most advanced phase
defining surfaces 62b, 65b. When the defining surfaces 62b, 65b
contact each other, the relative rotational phase of the rotary
valve 35 is most advanced, that is, the suction end timing of the
rotary valve 35 is most advanced. That is, the guide projection 65
and the groove 62 form an engaging mechanism that defines the most
advanced phase relative to the rotary shaft 16.
[0046] In contrast, as shown in FIG. 5, when the ball 63 is moved
radially outward from a certain position, the distance between the
power transmitting surfaces 61a, 65a and the power receiving
surface 62a is decreased while the surfaces 61a, 65a and 62a hold
the ball 63. To decrease the distance between the power
transmitting surfaces 61a, 65a and the power receiving surface 62a,
the rotary valve 35 needs to be shifted relative to the rotary
shaft 16 in a direction opposite to the rotational direction of the
rotary shaft 16. Shifting the rotary valve 35 relative to the
rotary shaft 16 in a direction opposite to the rotational
direction, that is, retarding the relative rotational phase of the
rotary valve 35 to the rotary shaft 16, retards the suction end
timing of the rotary valve 35.
[0047] The position of the ball 63 in the radial direction of the
rotary shaft 16 is determined by the equilibrium of centrifugal
force acting on the ball 63, an urging force, or the reaction force
from the power receiving surface 62a that acts on the ball 63 based
on torque transmitted from the rotary shaft 16 to the rotary valve
35, and the radially inward urging force of the spring 64. The
urging force based on the transmitted torque and the urging force
of the spring 64 are fixed parameters, which are determined during
the machine design. Only the centrifugal force is variable
parameter that varies according to the rotation speed of the rotary
shaft 16. Therefore, the position of the ball 63 is determined by
the rotation speed of the rotary shaft 16.
[0048] For example, when the rotation speed of the rotary shaft 16
is lowered, the centrifugal force acting on the ball 63 is
decreased, which causes the ball 63 to be moved radially inward by
the spring 64. Accordingly, the rotary valve 35 is rotated relative
to the rotary shaft 16 in the rotation direction, or the relative
rotational phase of the rotary valve 35 is advanced. This advances
the suction end timing of the rotary valve 35, and thus prevents
backflow of gas from the compression chambers 26 to the
introduction chamber 36, which tends to occur when the pistons 24
are at or in the vicinity of the bottom dead center. Accordingly,
the compression efficiency is prevented from being lowered by
backflow of gas.
[0049] In contrast, when the rotation speed of the rotary shaft 16
is increased, the centrifugal force acting on the ball 63 is
increased, which causes the ball 63 to be moved radially outward
against the spring 64. Accordingly, the rotary valve 35 is rotated
relative to the rotary shaft 16 in a direction opposite to the
rotation direction, or the relative rotational phase of the rotary
valve 35 is retarded. This retards the suction end timing of the
rotary valve 35. Therefore, even if the pistons 24 are at or in the
vicinity of the bottom dead center, suction by inertial force of
the gas is effectively used to increase the compression
efficiency.
[0050] In this embodiment, the ball 63 functions as a power
transmitting member forming the valve timing adjusting apparatus
60. The urging spring 64 and power receiving surface 62a, which
apply force to the ball 63 to determine the position of the ball
63, function as a position determining device that forms a part of
the valve timing adjusting apparatus 60.
[0051] The above embodiment provides the following advantages.
[0052] (1) The suction end timing of the rotary valve 35 is
adjusted by rotating the rotary valve 35 relative to the rotary
shaft 16, thereby changing the relative rotational phase of the
rotary valve 35 to the rotary shaft 16. For example, Japanese
Laid-Open Patent Publication No. 6-117363 discloses a technique to
move a rotary valve in the axial direction relative to a rotary
shaft, thereby adjusting the suction end timing. Compared to the
technique of the Japanese Laid-Open Patent Publication 6-117363,
the present invention is capable of reducing the size of the
compressor 10 in the direction of the axis L.
[0053] (2) The relative rotational phase of the rotary valve 35 to
the rotary shaft 16 is changed according to the rotation speed of
the rotary shaft 16. Therefore, the suction end timing of the
rotary valve 35 is optimized for the rotational speed of the rotary
shaft 16.
[0054] (3) The rotational phase of the rotary valve 35 is changed
to delay the suction end timing when the rotation speed of the
rotary shaft 16 is increased. In contrast, the rotational phase of
the rotary valve 35 is changed to advance the suction end timing
when the rotation speed of the rotary shaft 16 is decreased.
Accordingly, the compression efficiency of the compressor 10 is
increased as described above.
[0055] (4) A spherical body (steel ball 63) is used as a power
transmitting member. Since a spherical body need not be set in a
specific orientation, the ball 63 is easily assembled in the
compressor 10. For example, the ball 63 would neither be inclined
between the rotary shaft 16 and the rotary valve 35 nor be
immovable.
[0056] (5) The position of the ball 63, that is the suction end
timing of the rotary valve 35, is automatically changed based on
change in the centrifugal force acting on the ball 63. Therefore,
compared to a case where the position of the ball 63 is determined,
for example, by an actuator, the device for determining the
position of the ball 63 is simplified.
[0057] The invention may be embodied in the following forms.
[0058] In the above embodiment, the settings of the components are
determined while placing importance on the function of the rotary
valve 35 to change the suction end timing. Alternatively, the
settings of the components may be determined such that the rotary
valve 35 is capable of adjusting the suction start timing. That is,
the present invention is not limited to the suction end timing
adjusting apparatus as in the above embodiment, but may be embodied
in a suction start timing adjusting apparatus.
[0059] For example, the rotary valve 35 may have a bypass groove
for bypassing residual gas in a cylinder bore 23 in a state
immediately after a compression stroke to another cylinder bore in
a state immediately before the end of a suction stroke. The bypass
groove is thus capable of increasing the volumetric efficiency of
the compressor. In this configuration, the period of bypassing gas
is shortened as the rotation speed of the rotary shaft 16
increases. Therefore, the gas pressure in the cylinder bore 23 in a
state immediately after a compression stroke is not sufficiently
lowered. As a result, when a suction stroke of the cylinder bore 23
is started, backflow of gas occurs if the internal pressure of the
introduction chamber 36 in the rotary valve 35 is low, which can
add to the compressor noise.
[0060] Therefore, the configuration in which the suction start
timing is delayed when the rotary speed of the rotary shaft 16
increases is suitable for a compressor with a rotary valve that has
a bypass groove, since the configuration reduces the compressor
noise.
[0061] In the above embodiment, the position of the ball 63 is
automatically determined by the equilibrium of centrifugal force,
which varies according to the rotation speed of the rotary shaft
16, and the radially inward urging force applied by the urging
spring 64. This configuration may be changed. Specifically, an
actuator may be used to determine the position of the ball 63, or
the relative rotational phase of the rotary valve 35. In this case,
the valve timing of the rotary valve 35 is adjusted by the
actuator.
[0062] For example, as shown in FIG. 6, an actuator, which is an
electromagnetic attractive force applying device 70, may be
provided in a position in the cylinder block 11 surrounding the
joint of the rotary shaft 16 and the rotary valve 35. The
attractive force applying device 70 is capable of applying
electromagnetic attractive force (radially outward urging force) to
the steel ball 63. In this case, the urging spring 64 is configured
to have a strong spring force that does not permit the ball 63 to
be displaced during a high speed rotation of the rotary shaft 16.
Therefore, the position of the ball 63 in the radial direction is
adjusted according to the electromagnetic attractive force applied
to the ball 63 by the attractive force applying device 70.
[0063] The attractive force applying device 70 receives a driving
signal from the driving circuit 72 based on a command from the
control computer 71. The computer 71 and the driving circuit 72
form a control device. The attractive force applying device 70
applies to the steel ball 63 an electromagnetic attractive force
the magnitude of which corresponds to the driving signal from the
driving circuit 72. The control computer 71 adjusts the driving
signal supplied to the attractive force applying device 70 by the
driving circuit 72 based on detected information from a rotation
speed sensor 73 that detects the rotation speed of the rotary shaft
16.
[0064] When the rotation speed of the rotary shaft 16 increases,
the control computer 71 increases the electromagnetic attractive
force generated by the attractive force applying device 70, thereby
displacing the ball 63 radially outward. Accordingly, the suction
end timing of the rotary valve 35 is delayed. When the rotation
speed of the rotary shaft 16 decreases, the control computer 71
decreases the electromagnetic attractive force generated by the
attractive force applying device 70, thereby displacing the ball 63
radially inward. Accordingly, the suction end timing of the rotary
valve 35 is advanced.
[0065] For example, compared to the above embodiment of FIG. 2, in
which the position of the ball 63 is automatically determined by
centrifugal force (an internal control), the embodiment of FIG. 6
is capable of accurately determining the position of the ball 63.
In other words, the actual suction end timing is brought close to
an optimal suction end timing.
[0066] In the embodiment of FIG. 6, the position determining device
forming the valve timing adjusting apparatus 60 includes: the
urging spring 64, the power receiving surface 62a, and the
attractive force applying device 70, which apply force to the ball
63 for determining the position of the ball 63; the control
computer 71 and the driving circuit 72, which control the
attractive force applying device 70; and the rotation speed sensor
73, which provides the control computer 71 with the rotation speed
information of the rotary shaft 16.
[0067] In the embodiment of FIG. 6, the valve timing of the rotary
valve 35 is adjusted according to the rotation speed of the rotary
shaft 16. However, the valve timing of the rotary valve 35 may be
adjusted, for example, according to the displacement of the
compressor 10. The control computer 71 is capable of obtaining the
displacement of the compressor 10 based on information related to,
for example, current supplied to the displacement control valve 33.
That is, the capability to control the valve timing of the rotary
valve 35 permits the valve timing to be adjusted based on
information other than the information related to the rotation
speed of the rotary shaft 16.
[0068] In the above embodiments, the ball 63, which is a spherical
body, is used as the power transmitting member. However, the power
transmitting member may be a cylindrical body, a body formed by
combining a semispherical body and a cylindrical body, or a
triangle pole body, as long as the power transmitting member is
capable of transmitting power from the rotary shaft 16 to the
rotary valve 35.
[0069] In the above embodiments, the urging spring 64, which is a
coil spring, is used as the urging member. However, the urging
member may be, for example, a leaf spring, or a rubber body, as
long as the urging member is capable of urging the power
transmitting member.
[0070] The present invention may be applied to a wobble plate type
variable displacement compressor.
[0071] The present invention may be applied to a double-headed
piston type compressor.
[0072] The present invention may be applied to a wave cam type
compressor.
[0073] The present examples and embodiments are to be considered as
illustrative and not restrictive and the invention is not to be
limited to the details given herein, but may be modified within the
scope and equivalence of the appended claims.
* * * * *