U.S. patent application number 10/183884 was filed with the patent office on 2003-01-02 for rotor and compressor.
Invention is credited to Adaniya, Taku, Kanai, Akinobu, Kawaguchi, Masahiro, Kawata, Takeshi, Ota, Masaki, Suzuki, Takahiro.
Application Number | 20030000377 10/183884 |
Document ID | / |
Family ID | 19034401 |
Filed Date | 2003-01-02 |
United States Patent
Application |
20030000377 |
Kind Code |
A1 |
Kawata, Takeshi ; et
al. |
January 2, 2003 |
Rotor and compressor
Abstract
A rotor has a main body including a rotation axis, a weight
guide recessed in the main body, said weight guide having a weight
guide surface and a weight that is accommodated in the weight guide
and contacts with and rolls on a weight guiding surface. The weight
swings like a pendulum about a second axis. The second axis is
parallel to and offset from the rotation axis. The weight guiding
surface guides the weight to keep the weight moving within the
guiding surface.
Inventors: |
Kawata, Takeshi;
(Kariya-shi, JP) ; Kawaguchi, Masahiro;
(Kariya-shi, JP) ; Ota, Masaki; (Kariya-shi,
JP) ; Adaniya, Taku; (Kariya-shi, JP) ; Kanai,
Akinobu; (Kariya-shi, JP) ; Suzuki, Takahiro;
(Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
345 Park Avenue
New York
NY
10154
US
|
Family ID: |
19034401 |
Appl. No.: |
10/183884 |
Filed: |
June 27, 2002 |
Current U.S.
Class: |
92/70 |
Current CPC
Class: |
F02B 75/06 20130101;
F16H 2055/366 20130101; F16H 55/36 20130101; F16F 15/145
20130101 |
Class at
Publication: |
92/70 |
International
Class: |
F01B 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 28, 2001 |
JP |
2001-196630 |
Claims
1. A rotor comprising: a main body having a rotation axis; a weight
guide recessed in the main body, said weight guide having a weight
guide surface; and a weight that is accommodated in the weight
guide and contacts with and rolls on a weight guiding surface,
wherein the weight swings like a pendulum about a second axis, and
wherein the second axis is parallel to and offset from the rotation
axis; wherein the weight guiding surface guides the weight to keep
the weight moving within the guiding surface.
2. The rotor according to claim 1, wherein the weight guide surface
has a U-shaped cross-sectional surface along a plane that contains
the second axis.
3. The rotor according to claim 1, wherein the weight guide surface
has an inclined cross-sectional surface along a plane that contains
the second axis.
4. The rotor according to claim 1, wherein an annular groove or an
annular projection is formed in the circumferential portion of the
weight, and wherein a weight guiding path engaging with the
circumferential portion of the weight is formed in the weight
guiding surface, the weight guiding path being a projection or a
groove.
5. The rotor according to claim 4, wherein an inclined section is
formed in at least part of the weight guiding surface, and wherein
the weight guiding surface includes an inclined section.
6. The rotor according to claim 4, wherein the weight guiding path
on the weight guiding surface is a projection, and wherein the
circumferential portion of the weight has an annular groove.
7. A rotor comprising: a main body having a rotation axis; a weight
guide formed in the main body, said weight guide having an arcuate
shape in a cross-section along a plane perpendicular to the
rotation axis; and a weight accommodated in the weight guide, the
weight having a circular cross-section, wherein the weight rolls
along a weight guiding surface and swings like a pendulum about a
second axis, and wherein the second axis is separated from the
rotation axis by a predetermined distance and is parallel to the
rotation axis; wherein the weight guiding surface has a portion
that contacts the weight, wherein said contacting portion has a
cross-sectional surface along a plane containing the second axis,
said cross-section surface being substantially U-shaped such that
the weight is prevented from moving toward the second axis.
8. The rotor according to claim 7, wherein an annular groove or an
annular projection is formed in the circumferential portion of the
weight, and wherein a weight guiding path engaging with the
circumferential portion of the weight is formed in the weight
guiding surface, the weight guiding path being a projection or a
groove.
9. The rotor according to claim 8, wherein an inclined section is
formed in at least part of the weight guiding surface, and wherein
weight guiding surface includes an inclined section.
10. The rotor according to claim 8, wherein the weight guiding path
on the weight guiding surface is a projection, and wherein the
circumferential portion of the weight has an annular groove.
11. A rotor comprising: a main body haning a rotation axis; a
weight guide formed in the main body, said weight guide having an
arcuate shape in a cross-section along a plane perpendicular to the
rotation axis; a weight accommodated in the weight guide, the
weight having a circular cross-section, wherein the weight rolls
along a weight guiding surface and swings like a pendulum about a
second axis, and wherein the second axis is separated from the
rotation axis by a predetermined distance and is parallel to the
rotation axis; wherein the weight guiding surface has a portion
that contacts the weight, wherein the contacting portion has a
cross-sectional surface along a plane containing the second axis,
said cross-section surface being substantially U-shaped such that
the weight is prevented from moving toward the second axis; an
annular groove or an annular projection formed in the
circumferential portion of the weight; and a weight guiding path
formed in the weight guiding surface, the weight guiding path
engaging with the circumferential portion of the weight, wherein
the weight guiding path being a projection or a groove.
12. The rotor according to claim 11, wherein an inclined section is
formed in at least part of the weight guiding surface, and wherein
the weight guiding surface includes an inclined section.
13. The rotor according to claim 12, wherein the weight guiding
path on the weight guiding surface is a projection, and wherein the
circumferential portion of the weight has an annular groove.
14. A compressor driven by power of a vehicle engine, comprising: a
pulley receiving power from the engine; a weight guide formed in
the pulley, wherein the weight guide has an arcuate shape in a
cross-section along a plane perpendicular to the rotation axis; and
a weight accommodated in the weight guide, the weight having a
circular cross-section, wherein the weight rolls along a weight
guiding surface and swings like a pendulum about a second axis, and
wherein the second axis is separated from the rotation axis by a
predetermined distance and is parallel to the rotation axis;
wherein the weight guiding surface has a portion that contacts the
weight, wherein the contacting portion has a cross-sectional
surface along a plane that contains the second axis, the
cross-section surface being inclined relative to the second axis
such that the weight is prevented from moving toward the second
axis.
15. The compressor according to claim 14, wherein the cross-section
surface of the contacting portion is substantially U-shaped.
16. The compressor according to claim 14, wherein an annular groove
or an annular projection is formed in the circumferential portion
of the weight, and wherein a weight guiding path engaging with the
circumferential portion of the weight is formed in the weight
guiding surface, the weight guiding path being a projection or a
groove.
17. The compressor according to claim 16, wherein an inclined
section is formed in at least part of the weight guiding surface,
and wherein the weight guiding surface includes an inclined
section.
18. A rotor comprising: a main body having a rotation axis; a
weight guide formed in the main body, said weight guide having an
arcuate shape in a cross-section along a plane perpendicular to the
rotation axis, said weight guide having a weight guide surface; and
a weight accommodated in the weight guide, the weight having a
circular cross-section, wherein the weight rolls along a weight
guiding surface and swings like a pendulum about a second axis, and
wherein the second axis is separated from the rotation axis by a
predetermined distance and is parallel to the rotation axis;
wherein the weight guiding surface has a portion that contacts the
weight, wherein said contacting portion has a cross-sectional
surface along a plane that contains the second axis, said
cross-sectional surface is inclined relative to the second axis
such that the weight is prevented from moving in the direction of
the second axis.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a rotor having a weight
that swings like a pendulum and to a compressor that uses the
rotor.
[0002] Japanese Laid-Open Patent Publication No. 6-193684 discloses
a rotor having a flywheel, in which a weight guide (weight
receptacle) is defined. A weight (damper mass) is accommodated in
the weight guide (weight receptacle). The weight rolls in the
weight receptacle. A projection having a rectangular cross-section
is formed in one of the weight guide and the weight. A groove
having a rectangular cross section is formed in the other one of
the guide and the weight. The projection and the groove extend
along the rolling direction of the weight and engage with each
other. The engagement of the projection and the groove prevents the
weight from moving in the axial direction of the rotor. Thus, the
weight does not collide with the walls of the weight guide, which
suppresses the noise due to collision.
[0003] However, a clearance must be created between the projection
and the groove to allow the weight to swing like a pendulum. The
clearance permits the weight to move in the axial direction. The
weight therefore chatters and produces noise.
SUMMARY OF THE INVENTION
[0004] Accordingly, it is a major objective of the present
invention to provide a rotor that suppresses resonance by
pendulum-like motion of a weight accommodated in a weight guide and
reduces noise produced by collision of the weight against the walls
of the receptacle.
[0005] It is a further objective of the present invention to
provide a compressor that uses the rotor.
[0006] To achieve the foregoing and other objectives and in
accordance with the purpose of the present invention, a rotor has a
main body including a rotation axis, a weight guide recessed in the
main body, said weight guide having a weight guide surface and a
weight that is accommodated in the weight guide and contacts with
and rolls on a weight guiding surface. The weight swings like a
pendulum about a second axis. The second axis is parallel to and
offset from the rotation axis. The weight guiding surface guides
the weight to keep the weight moving within the guiding
surface.
[0007] 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
[0008] 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:
[0009] FIG. 1 is a cross-sectional view illustrating a compressor
having a pulley according to one embodiment of the present
invention;
[0010] FIG. 2(a) is a front view illustrating the pulley of FIG.
1;
[0011] FIG. 2(b) is a cross-sectional view taken along line b-b of
FIG. 2(a);
[0012] FIG. 3(a) is an enlarged partial cross-sectional view
illustrating a groove and a roller (weight) according to another
embodiment;
[0013] FIG. 3(b) is an enlarged partial cross-sectional view
illustrating a groove and a roller (weight) according to another
embodiment;
[0014] FIG. 3(c) is an enlarged partial cross-sectional view
illustrating a groove and a roller (weight) according to another
embodiment; and
[0015] FIG. 3(d) is an enlarged partial cross-sectional view
illustrating a groove and a roller (weight) according to another
embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] A compressor C according to one embodiment of the present
invention will now be described with reference to FIGS. 1 to 2(b).
The left end of the compressor C in FIG. 1 is defined as the front
of the compressor, and the right end is defined as the rear of the
compressor C.
[0017] As shown in FIG. 1, the compressor C includes a cylinder
block 11, a front housing member 12, a valve plate 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
plate assembly 13 in between. The cylinder block 11, the front
housing 12, the valve plate assembly 13, and the rear housing
member 14 form the housing of the compressor C.
[0018] The cylinder block 11 and the front housing member 12 define
a crank chamber 15 in between.
[0019] A rotary shaft, which is a drive shaft 16 in this
embodiment, is housed in the compressor housing and extends through
the crank chamber 15.
[0020] A cylindrical support 40 is formed at the front end of the
front housing member 12. The front end portion of the drive shaft
16 extends through the front wall of the front housing member 12
and is located in the cylindrical support 40. The front end portion
of the drive shaft 16 is coupled to an external drive source, which
is a vehicular engine E in this embodiment, by a rotor, which is a
pulley 17 in this embodiment, and a belt 18 wound around the pulley
17.
[0021] A lug plate 19 is coupled to the drive shaft 16 and is
located in the crank chamber 15. The lug plate 19 rotates
integrally with the drive shaft 16. A cam plate, which is a swash
plate 20 in this embodiment, is housed in the crank chamber 15. The
swash plate 20 slides along and inclines with respect to the drive
shaft 16. The swash plate 20 is coupled to the lug plate 19 by the
hinge mechanism 21. The lug plate 19 permits the swash plate 20 to
rotate integrally with the drive shaft 16 and to incline with
respect to the drive shaft 16 while sliding along the rotation axis
of the drive shaft 16.
[0022] A snap ring 22 is fitted about the drive shaft 16. A spring
23 extends between the snap ring 22 and the swash plate 20. The
snap ring 22 and the spring 23 limit the minimum inclination angle
of the swash plate 20. At the minimum inclination angle of the
swash plate 20, the angle defined by the swash plate 20 and the
axis of the drive shaft 16 is closest to ninety degrees.
[0023] Cylinder bores 24 (only one is shown in FIG. 1) are formed
in the cylinder block 11. The cylinder bores 24 are located about
the rotation axis of the drive shaft 16. A single-headed piston 25
is reciprocally housed in each cylinder bore 24. The front and rear
openings of each cylinder bore 24 are closed by the associated
piston 25 and the valve plate assembly 13. A compression chamber is
defined in each cylinder bore 24. The volume of the compression
chamber changes according to the reciprocation of the corresponding
piston 24. Each piston 25 is coupled to the peripheral portion of
the swash plate 20 by a pair of shoes 26. When the swash plate 20
is rotated by rotation of the drive shaft 16, the shoes 26 converts
the rotation into reciprocation of each piston 25.
[0024] The drive shaft 16, the lug plate 19, the swash plate 20,
the hinge mechanism 21, the pistons 25, and the shoes 26 form a
piston type compression mechanism.
[0025] Sets of suction ports 29 and suction valve flaps 30 and sets
of discharge ports 31 and discharge valve flaps 32 are formed in
the valve plate assembly 13. Each set of the suction port 29 and
the corresponding suction valve flap 30 and each set of the
discharge port 31 and the corresponding discharge valve flap 30
correspond to one of the cylinder bores 24 (compression
chambers).
[0026] A suction chamber 27 and a discharge chamber 28 are defined
in the rear housing member 14. The front ends of the suction
chamber 27 and the discharge chamber 28 are closed by the valve
plate assembly 13. As each piston 25 moves from the top dead center
position to the bottom dead center position, refrigerant gas is
drawn into the corresponding cylinder bore 24 (compression chamber)
through the corresponding suction port 29 while flexing the suction
valve flap 30 to an open position. Low pressure refrigerant gas
that is drawn into the cylinder bore 24 is compressed to a
predetermined pressure as the piston 25 is moved from the bottom
dead center position to the top dead center position. Then, the gas
is discharged to the discharge chamber 28 through the corresponding
discharge port 31 while flexing the discharge valve flap 32 to an
open position.
[0027] The suction chamber 27 is connected to the discharge chamber
28 by an external refrigerant circuit (not shown). Refrigerant that
is discharged from the discharge chamber 28 flows into the external
refrigerant circuit. The external refrigerant circuit performs heat
exchange using the refrigerant. When discharged from the external
refrigerant circuit, the refrigerant is drawn into the suction
chamber 27. Then, the refrigerant is drawn into each cylinder bore
24 to be compressed again.
[0028] A bleed passage 33 is formed in the housing to connect the
crank chamber 15 with the suction chamber 27. A supply passage 34
is formed in the housing to connect the discharge chamber 28 with
the crank chamber 15. A control valve 35 is located in the supply
passage 34 to regulate the opening degree of the supply passage 34.
The opening of the control valve 35 is adjusted to control the flow
rate of highly pressurized gas supplied to the crank chamber 15
through the supply passage 34.
[0029] The pressure in the crank chamber 15 (crank chamber pressure
Pc) is determined by the ratio of the gas supplied to the crank
chamber 15 through the supply passage 34 and the flow rate of
refrigerant gas conducted out from the crank chamber 15 through the
bleed passage 33. As the crank chamber pressure Pc varies, the
difference between the crank chamber pressure Pc and the pressure
in the compression chambers varies, which changes the inclination
angle of the swash plate 20. Accordingly, the stroke of each piston
25, or the compressor displacement, is varied.
[0030] As shown in FIGS. 1 and 2(b), the pulley 17 is located about
and rotatably supported by the support cylinder 40 with a bearing
41. The pulley 17 is also fixed to the drive shaft 16 to rotate
integrally with the drive shaft 16.
[0031] As shown in FIGS. 1 and 2, the pulley 17 includes a main
body 42 (rotor main body). The pulley main body 42 has a boss 43,
which is fitted about the outer ring of the bearing 41, and a belt
receiving portion 44, which is wound around the belt 18. Two weight
receptacles 45 are formed between the boss 43 and the belt
receiving portion 44. The weight receptacles 45 are symmetrically
arranged with respect to the rotation axis of the main body 42.
[0032] A weight guiding surface 46 is formed in each weight
receptacle 45. A cross section of the weight guiding surface 46
along a plane perpendicular to the rotation axis of the pulley main
body 42 is arcuate. The center of curvature of the weight guiding
surface 46 coincides with a line that extends parallel to and is
spaced from the rotation axis of the pulley main body 42 by a
predetermined distance R.sub.1. Each weight guiding surface 46 is
formed at a side of the corresponding weight receptacle 45 that is
close to the periphery of the pulley main body 42.
[0033] A weight guiding path, which is a groove 46A in this
embodiment, extends along the circumferential direction of each
weight guiding surface 46, or in the direction along which a weight
ball 48 rolls. The cross section of the groove 46A along a plane
containing the center of curvature of the weight guiding surface 46
(cross section shown in FIGS. 1 and 2(b)) is arcuate. The radius of
curvature of each groove 46A represented by r.sub.1. Arcuate inner
surfaces 46B are formed at the front and rear sides of the groove
46A in each weight guiding surface 46. The arcuate inner surfaces
46B form parts of the inner surface of a common imaginary
cylinder.
[0034] An auxiliary guiding surface 47 is formed in each weight
receptacle 45. The auxiliary guiding surface 47 is separated from
the arcuate inner surfaces 46B toward the axis of the pulley main
body 42 by a predetermined distance. As viewed from the front side
of the compressor C, each weight receptacle 45 appears as an arc
having a constant width with its middle portion located closer to
the periphery of the pulley main body 42 than its ends. As viewed
from the front side of the compressor C, each weight receptacle 45
is symmetrical with respect to an imaginary line that contains the
rotation axis of the pulley main body 42 and the center of the
corresponding imaginary cylinder.
[0035] Each of the grooves 46A has a substantially U-shape in cross
section. In other words, the edge of the groove 46A extending to
form the U-shape is inclined with respect to the axis of the
pendulum motion.
[0036] A weight, which is a rigid weight ball 48 in this
embodiment, is accommodated in each weight receptacle 45. The mass
of each weight ball 48 is referred to as m.sub.1. The diameter
d.sub.1 of each weight ball 48 is slightly less than the distance
between the arcuate inner surfaces 46B and the auxiliary guiding
surface 47. The diameter d.sub.1 is equal to the doubled radius
r.sub.1 of curvature of the groove 46A. The axial size of each
groove 46A is slightly less than the diameter d.sub.1 of the weight
ball 48 so that substantially a half of the weight ball 48 is
fitted in the groove 46A. Each weight ball 48 linearly contacts the
corresponding groove 46A with a part (substantially a half) fitted
in the groove 46A. In this state, the weight ball 48 moves along
the groove 46A.
[0037] An annular cover 49 is fixed to the pulley 17 by screws (not
shown) to cover the receptacles 45. Even if the weight balls 48 are
dislocated from the grooves 46A, the cover 49 prevents the weight
balls 48 from falling off the receptacles 45. The receptacles 45
and the cover 49 form weight guides.
[0038] When the compressor C is being driven by the engine E, or
when the drive shaft 16 is rotating, the weight balls 48 linearly
contact the grooves 46A due to the centrifugal force (see FIGS. 1
to 2(b)). If a torque is generated by rotational fluctuation of the
drive shaft 16, each weight ball 48 reciprocates along the groove
46A in the corresponding weight receptacle 45. In other words, the
weight ball 48, or its center of gravity, swings like a pendulum
about the center of curvature of the corresponding weight guiding
surface 46. That is, each weight ball 48 acts as a centrifugal
pendulum when the compressor C is being driven by the engine E.
[0039] The size and weight of the weight balls 48 and the locations
of the weight balls 48 in the pulley main body 42 are determined
such that the torque fluctuation is suppressed by pendulum motion
of the weight balls 48.
[0040] The settings of the weight balls 48, which function as
centrifugal pendulums, will now be described.
[0041] The weight balls 48 suppress torque fluctuation.
Specifically, each weight ball 48 suppresses a fluctuation band at
a frequency that is equal to the characteristic frequency of the
weight ball 48 (centrifugal pendulum). Therefore, the location, the
size, and the weight of each weight ball 48 are determined such
that the characteristic frequency of the weight ball 48 is set
equal to the frequency of a peak component of the torque
fluctuation. Accordingly, the amplitude of the peak component is
suppressed, and the influence of the torque fluctuation is
effectively reduced. Peak components of the torque fluctuation
represent the peaks of the fluctuation band, or the components of
rotation order.
[0042] The frequency of the torque fluctuation and the
characteristic frequency of the weight balls 48 are proportional to
the angular velocity .omega..sub.1 of the drive shaft 16, which
corresponds to the speed of the drive shaft 16. The frequency of
the torque fluctuation when its band is greatest is represented by
the product of the rotation speed of the drive shaft 16 per unit
time (.omega..sub.1/2) and the number N of the cylinder bore 24.
That is, the frequency is represented by the formula
(.omega..sub.1/2.pi.) N.
[0043] Through experiments, it was confirmed that an nth greatest
peak (n is a natural number) of the torque fluctuation has a value
equal to a product n.multidot.(.omega..sub.1/2.pi.).multidot.N.
[0044] The characteristic frequency of the weight balls 48 is
obtained by multiplying the rotation speed of the drive shaft 16
per unit time (.omega..sub.1/2.pi.) with the square root of the
ratio R/r. The sign R represents the distance between the rotation
axis of the pulley main body 42 and the axis of the pendulum motion
of each weight ball 48. The sign r represents the distance between
the axis of the pendulum motion of each weight ball 48 and the
center of gravity of the weight ball 48.
[0045] Therefore, by equalizing the square root of the ratio R/r
with the product n.multidot.N, the characteristic frequency of the
weight balls 48 are equal to the frequency of the nth greatest peak
of the torque fluctuation. Accordingly, the torque fluctuation at
the nth greatest peak is suppressed.
[0046] To suppress the greatest peak of the torque fluctuation, the
values of the distances R and r are determined such that the square
root of the ratio R/r is equal to N, or the value of the product
n.multidot.N when n is one.
[0047] The torque produced about the rotation axis of the pulley
main body 42 by the weight balls 48 is represented by a sign T. To
effectively reduce the torque fluctuation by the pendulum motion of
the weight balls 48, the torque T needs to counter the torque
fluctuation and the range of the torque T needs to be equal to the
range of the fluctuation. When the frequency of a peak of the
torque fluctuation is equal to the characteristic frequency of the
weight balls 48, the torque T is represented by the following
equation.
T=m.multidot.(.omega..sub.a).sup.2.multidot.(R+r).multidot.R.multidot..phi-
. (Equation 1)
[0048] In the equation 1, the sign m represents the total mass of
the weight balls 48 (m=2m.sub.1), and .omega..sub.a represents the
average angular velocity of the swing balls when the balls swing in
a minute angle .phi..
[0049] In this embodiment, the mass m is maximized to minimize the
values R, r, and .phi., so that the size of the pulley main body 42
is minimized, and the torque T is maximized.
[0050] The center of curvature of each weight guiding surface 46
coincides with the axis of the pendulum motion of the corresponding
ball 48. That is, the distance R.sub.1 between the rotation axis of
the pulley main body 42 and the center of curvature of each weight
guiding surface 46 corresponds to the distance R.
[0051] The settings are determined by regarding the weight ball 48
as a particle at the center of gravity.
[0052] The operation of the compressor C will now be described.
[0053] When the power of the engine E is supplied to the drive
shaft 16 through the pulley 17, the swash plate 20 rotates
integrally with the drive shaft 16. As the swash plate 20 rotates,
each piston 25 reciprocates in the associated cylinder bore 24 by a
stroke corresponding to the inclination angle of the swash plate
20. As a result, suction, compression and discharge of refrigerant
gas are repeated in the cylinder bores 24.
[0054] If the opening degree of the control valve 35 is decreased,
the flow rate of highly pressurized gas supplied to the crank
chamber 15 from the discharge chamber 28 through the supply passage
34 is decreased. Accordingly, the crank chamber pressure Pc is
lowered and the inclination angle of the swash plate 20 is
increased. As a result, the displacement of the compressor C is
increased. If the opening degree of the control valve 35 is
increased, the flow rate of highly pressurized gas supplied to the
crank chamber 15 from the discharge chamber 28 through the supply
passage 34 is increased. Accordingly, the crank chamber pressure Pc
is raised and the inclination angle of the swash plate 20 is
decreased. As a result, the displacement of the compressor C is
decreased.
[0055] During rotation of the drive shaft 16, the compression
reaction force of refrigerant and reaction force of reciprocation
of the pistons 25 are transmitted to the drive shaft 16 through the
swash plate 20 and the hinge mechanism 21, which torsionally
(rotationally) vibrates the drive shaft 16. The torsional
vibrations generate torque fluctuation. The torque fluctuation
causes the compressor C to resonate. The torque fluctuation also
produces resonance between the compressor C and rotary machines
(the engine E and auxiliary devices), which are connected to the
pulley 17 by the belt 18.
[0056] When the torque fluctuation is produced, the weight balls 48
start swinging like pendulums. The pendulum motion of the weight
balls 48 produces torque about the rotation axis of the pulley main
body 42. The produced torque suppresses the torque fluctuation. The
characteristic frequency of each weight ball 48 is equal to the
frequency of the greatest peak of the torque fluctuation.
Therefore, the peak of the torque fluctuation is suppressed, which
effectively reduces the torque fluctuation of the pulley 17. As a
result, the resonance produced by the torque fluctuation is
effectively suppressed.
[0057] The present embodiment has the following advantages.
[0058] (1) The weight balls 48 are provided in the pulley main body
42. The axis of each weight ball 48 is spaced from the rotation
axis of the pulley main body 42 by the predetermined distance
R.sub.1 and is parallel to the rotation axis of the pulley main
body 42. Each weight ball 48 swings like a pendulum about its axis.
The pendulum motion of the weight balls 48 suppresses the torsional
vibration of the pulley 17, which suppresses resonance produced in
the compressor C. Further, the pendulum motion suppresses resonance
produced between the compressor C and the rotary machines that are
coupled to the pulley 17 by the belt 18.
[0059] (2) The groove 46A is formed in each weight guiding surface
46. A cross section of each groove 46A along a plane containing the
axis of pendulum motion of the corresponding weight ball 48 is
substantially U-shaped. In the other words, the cross section of
the groove 46A is not parallel, or inclined to the axis of the
pendulum motion. The weight ball 48 is pressed against the groove
46A by centrifugal force, which prevents the weight ball 48 from
moving in the axial direction. Therefore, the weight ball 48 is
prevented from colliding with the inner walls of the weight guide,
which reduces the noise.
[0060] (3) Each groove 46A, which contacts one of the weight balls
48, has an arcuate cross section along a plane containing the axis
of the pendulum motion. The radius r.sub.1 of curvature of the
groove 46A is equal to a half of the diameter d.sub.1 of the weight
ball 48, or the radius of the weight ball 48. Therefore, when the
weight ball 48 swings along the groove 46A, there is no clearance
between the weight ball 48 and the groove 46A that permits the
weight ball 48 to move axially.
[0061] (4) The axial size of each groove 46A is slightly less than
the diameter d.sub.1 of the weight ball 48 so that substantially a
half of the weight ball 48 is fitted in the groove 46A. Compared to
a case in which the axial size of the groove 46A is narrower, a
greater part of the weight ball 48 is located in the groove 46A
when the weight ball 48 swings along the groove 46A. Therefore, the
weight ball 48 is less likely to be dislocated.
[0062] It should be apparent to those skilled in the art that the
present invention may be embodied in many other specific forms
without departing from the spirit or scope of the invention.
Particularly, it should be understood that the invention may be
embodied in the following forms.
[0063] In the embodiment of FIGS. 1 to 2(b), the cross section of
each groove 46A along the plane containing the axis of the pendulum
motion is arcuate. The axial size of each groove 46A is determined
such that a half of the corresponding weight ball 48 is received by
the groove 46A. However, the axial size of each groove 46A may be
changed. For example, the axial size of each groove 46A may be
determined such that a smaller portion of the weight ball 48 is
received by the groove 46A.
[0064] In the embodiment of FIGS. 1 to 2(b), the weight guides (the
weight receptacles 45) are arcuate and have a constant width when
viewed from the front side of the compressor C. However, the shape
of each weight receptacle 45 may be changed. As long as each weight
receptacle 45 has a weight guiding surface, the shape of the weight
receptacle 45 may be changed, for example, to a circular shape.
[0065] In the embodiment of FIGS. 1 to 2(b), the diameter d.sub.1
of each weight ball 48 is equal to the doubled radius r.sub.1 of
curvature of the groove 46A. However, the diameter d.sub.1 may be
changed. For example, the diameter d.sub.1 may be less than the
doubled radius r.sub.1. In this case, even if an external force in
the axial direction of the pendulum motion is applied to the weight
ball 48, the weight ball 48 remains contacting the surface of the
groove 46A and reciprocates along the width of the groove 46A. That
is, noise due to collision between the weight ball 48 and the
groove 46A is prevented. If the diameter d.sub.1 is greater than
the doubled radius r.sub.1, the weight ball 48 is prevented from
moving in the axial direction by the edges of the groove 46A.
[0066] In the embodiment of FIGS. 1 to 2(b), each groove 46A, which
contacts the weight ball 48, has an arcuate cross section along a
plane containing the axis of the pendulum motion. However, the
cross section of the groove 46A may be U-shaped. In other words,
the cross section of the groove 46A may be changed as long as there
is no clearance between the weight ball 48 and the groove 46A that
permits the weight ball 48 to move axially when the weight ball 48
swings along the groove 46A.
[0067] In the embodiment of FIGS. 1 to 2(b), the cross section of
part of each weight guiding surface 46 along the plane containing
the axis of the pendulum motion is arcuate. However, at least part
of each weight guiding surface may include an inclined surface and
formed as a projection or a groove that extends along the
reciprocation direction of the weight. In this case, the outer
shape of the weight is preferably shaped to fit the projection or
the groove formed in the weight receptacle. FIGS. 3(a) to 3(c)
describe weight receptacles of such embodiments. FIGS. 3(a) to 3(c)
are cross-sectional views of the cover 49, weight receptacles 51,
53, 55 forming weight guides, and weights, which are rollers (52,
54, 56) located in the weight receptacles (51, 53, 55) taken along
a plane containing the axis of the pendulum motion of the rollers
(52, 54, 56).
[0068] The weight receptacle 51 shown in FIG. 3(a) has a weight
guiding surface 51A. Inclined sections 51B, 51C are formed in the
axial ends of the weight guiding surface 51A. Therefore, the weight
guiding surface 51A is formed as a groove extending along the
reciprocation direction of the substantially cylindrical roller 52.
An arcuate surface 51D is formed between the inclined section 51B,
51C. The arcuate surface 51D is a part of an imaginary cylinder the
center of which coincides with the axis of the pendulum motion. The
roller 52 has an annular projection 52A. The projection 52A fits in
the groove defined by the inclined sections 51B, 51C.
[0069] The weight receptacle 53 shown in FIG. 3(b) has a weight
guiding surface 53A. Inclined sections 53B, 53C are formed in the
guiding surface 53A. Therefore, the weight guiding surface 53A is
formed as a groove extending along the reciprocation direction of
the roller 54. The inclined sections 53B, 53C are adjacent to each
other. The roller 54 has an annular projection 54A. The projection
54A fits in the groove defined by the inclined sections 53B,
53C.
[0070] The weight receptacle 55 shown in FIG. 3(c) has a weight
guiding surface 55A. Inclined sections 55B, 55C are formed in the
guiding surface 55A. Therefore, the guiding surface 55A is formed
as a projection extending along the reciprocation direction of the
roller 56. The inclined sections 55B, 55C are adjacent to each
other. The roller 56 has an annular groove 56A. The groove 56A fits
on the projection defined by the inclined sections 55B, 55C. In the
embodiments of FIGS. 3(a) to 3(c), the engagement between the
weight and the groove or the projection prevents the weight from
being displaced in the axial direction. Therefore, the weight is
prevented from colliding with the inner walls of the weight
guide.
[0071] In the embodiment of FIG. 3(c), the pulley main body 42 is
formed by coupling two pieces the boundary of which is shown by
broken lines. The pulley pieces are molded by dies that move along
the axial direction of the pulley main body 42 and then coupled to
each other. Therefore, undercuts are not formed. This facilitates
the forming of the pulley main body 42 and reduces the cost.
[0072] The cross section of the weight guiding surface along the
plane containing the axis of the pendulum motion may form a line
that is inclined relative to the axis of the pendulum motion. FIGS.
3(d) describes such an embodiment.
[0073] FIGS. 3(d) is cross-sectional view of the cover 49, a weight
receptacle 57 forming a weight guide, and a weight, which is a
roller 58, located in the weight receptacles 57 taken along the
plane containing the axis of the pendulum motion of the roller 58.
The weight receptacle 57 includes a roller guiding surface 57A. The
roller guiding surface 57A is inclined that the weight receptacle
57 is radially widened toward the open end (the left end as viewed
in FIG. 3(d)). The roller 58 swings along the guide 57A like a
pendulum. The roller 58 is formed as a frustum. The circumference
of the roller 58 is inclined such that the roller 58 linearly
contacts the guide 57A.
[0074] When the roller 58 is swinging along the guiding surface
57A, the front end (the left end as viewed in FIG. 3(d)) of the
roller 58 contacts the cover 49, which is located at the open end
of the weight receptacle 57. The contact between the guiding
surface 57A and the circumference of the roller 58 prevents the
roller 58 from moving rearward (rightward as viewed in FIG. 3(d)).
Also, the contact between the cover 49 and the front surface of the
roller 58 prevents the roller 58 from moving forward. Therefore,
the weight is prevented from colliding with the inner walls of the
weight guide.
[0075] In the embodiment of FIGS. 3(d), the pulley main body 42 is
molded by dies that move along the axial direction of the pulley
main body 42. The guide 57A is formed when the pulley main body 42
is molded. Therefore, undercuts are not formed. This facilitates
the forming of the pulley main body 42 and reduces the cost.
[0076] In the embodiment of FIG. 3(d), the weight receptacle 57 is
radially widened toward the open end. However, the weight
receptacle 57 may be narrowed toward the open end. In this case,
the weight (roller) is prevented from moving in the axial direction
by the guiding surface and the wall that faces the cover 49.
[0077] In the embodiment of FIG. 3(d), the weight is formed like a
fulcrum linearly contacts the guiding surface. However, the weight
may be spherical and in point contact with the guiding surface.
[0078] For example, an axial projection 61 may be formed on either
side of the weight (52) as illustrated by broken lines in FIG.
3(a). In this case, when the weight moves in the axial direction,
the projections 61 contact the inner walls of the weight guide.
Therefore, compared to a case where there is no axial projections
like projections 61 and the entire axial surfaces contact the inner
walls when the weight moves axially, the weight having the
projections 61 contacts the inner walls at smaller areas and
produces less noise. In other words, the noise is reduced.
[0079] In the embodiment of FIGS. 1 to 2(b), the square root of the
ratio R/r is equal to N, which is the value of n.multidot.N when
the n is one. However, the square root of the ratio R/r may be the
value of n.multidot.N when n is a natural number that is greater
than one.
[0080] In the embodiment of FIGS. 1 to 2(b), the pulley main body
42 has two weight guides each accommodating a weight. However, the
number of the weight guides may be changed. The number of the
weight guides need not correspond to the number of the cylinder
bores of the compressor C. If the pulley main body 42 has only one
mass, the pulley main body 42 may have a balancer such as a weight
or a thinned portion to prevent the center of gravity of the pulley
main body 42 from being displaced.
[0081] If the pulley main body 42 has two or more weights, the
ratio R/r of the weights may be different. Since there is two or
more values of the ratios R/r of the weights, the bands of two or
more peaks (rotation order) of the torque fluctuation are
suppressed. In this case, the values n are preferably selected from
numbers in order from one. For example, when three numbers are
selected, one, two and three are preferably used. Accordingly, the
square roots of the ratios R/r correspond to the numbers
represented by the products n.multidot.N, in which the value n is
one, two and three. Therefore, the three greatest peaks of the
torque fluctuation are suppressed. That is, the resonance is
effectively suppressed.
[0082] In the illustrated embodiments, the settings are determined
by regarding each weight as a particle at the center of gravity.
However, the settings are preferably determined by taking the
inertial mass of each weight into consideration. For example, in
the case of the weight balls 48, the settings are preferably made
based on the ratio 5R/7r instead on the ratio R/r so that the
inertial mass of the weight balls 48 are taken into consideration.
When the frequency of a peak of the torque fluctuation is equal to
the characteristic frequency of the weight balls 48, the torque T
is represented by the following equation.
T=(7/5).multidot.m.multidot.(.omega..sub.a).sup.2.multidot.(R+r).multidot.-
R.multidot..phi. (Equation 2)
[0083] If the weights are formed in a shape other than spherical
shapes, the settings are preferably made by taking the inertial
mass of the weight into consideration so that the resonance is
effectively suppressed.
[0084] In the illustrated embodiments, the pulley 17 is used for
the compressor C, which has the single headed pistons 25. However,
the pulley 17 may be used for a compressor that has double-headed
pistons. In this type of compressor, cylinder bores are formed on
either side of a crank chamber and each piston compresses gas in
the corresponding pair of the cylinder bores.
[0085] In the illustrated embodiment, the cam plate (the swash
plate 20) rotates integrally with the drive shaft 16. However, the
present invention may be applied to a compressor in which a cam
plate rotates relative to a drive shaft. For example, the present
invention may be applied to a wobble type compressor.
[0086] The present invention may be applied to a fixed displacement
type compressor, in which the stroke of the pistons are not
variable.
[0087] In the illustrated embodiments, the present invention is
applied to a reciprocal piston type compressor. However, the
present invention may be applied to rotary compressors such as a
scroll type compressor
[0088] The present invention may be applied to any type or rotor
other than pulley. For example, the present invention may be
applied to a sprocket or a gear.
[0089] The present invention may be applied to a rotating member
located in the housing of the compressor C. For example, the lug
plate 19, which is located in the housing and coupled to the drive
shaft 16, may have the weights to suppress the rotational
vibrations produced in the drive shaft 16. In this case, resonance
in the compressor C is suppressed and noise produced by collision
between the weights and the weight guides is reduced. Moreover,
since the weights are located in the compressor C, little noise
escapes the compressor C.
[0090] In the illustrated embodiments, the present invention is
applied to the compressor C. However, the present invention may be
applied to other apparatuses. Specifically, the present invention
may be applied to any apparatus in which rotational vibration is
produced.
[0091] The axis of the pendulum motion of each weight need not be
parallel to the rotation axis of the rotor. Specifically, the axis
of the pendulum motion may be inclined relative to the rotation
axis of the rotor in a range in which the maximum torque
fluctuation is suppressed by a desirable degree.
[0092] Therefore, 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.
* * * * *