U.S. patent application number 11/034022 was filed with the patent office on 2005-08-04 for rotating fluid machine.
This patent application is currently assigned to HONDA MOTOR CO., LTD.. Invention is credited to Ishikawa, Seiichiro, Saitou, Bunichi.
Application Number | 20050169772 11/034022 |
Document ID | / |
Family ID | 34805333 |
Filed Date | 2005-08-04 |
United States Patent
Application |
20050169772 |
Kind Code |
A1 |
Saitou, Bunichi ; et
al. |
August 4, 2005 |
Rotating fluid machine
Abstract
At a contact point, a spherical projecting portion of a piston
presses a spherical recessed portion of a swash plate due to a
working medium supplied to an operating chamber. The contact point
is located on a cross line, on which a plane including a center of
curvature of the spherical recessed portion and an axis Ls of the
swash plate intersects the spherical recessed portion. Therefore,
even if the piston forcefully presses the swash plate, the
spherical projecting portion and the spherical recessed portion at
the contact point are prevented from slipping in a circumferential
direction, a radial direction and the like. Thus, the phases of a
rotor and the swash plate are prevented from being displaced and
causing vibration and noise. A large side thrust is prevented from
acting on the piston and causing heat due to twisting and sliding
friction between the piston and the cylinder.
Inventors: |
Saitou, Bunichi; (Wako-shi,
JP) ; Ishikawa, Seiichiro; (Wako-shi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
HONDA MOTOR CO., LTD.
Tokyo
JP
|
Family ID: |
34805333 |
Appl. No.: |
11/034022 |
Filed: |
January 13, 2005 |
Current U.S.
Class: |
417/269 ;
417/375 |
Current CPC
Class: |
F04B 27/0886 20130101;
F04B 1/2085 20130101; F01B 3/007 20130101 |
Class at
Publication: |
417/269 ;
417/375 |
International
Class: |
F01B 003/00; F04B
001/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 16, 2004 |
JP |
2004-8813 |
Claims
What is claimed is:
1. A rotating fluid machine comprising: a casing; a rotor rotatably
supported by the casing; an axial piston cylinder group annularly
disposed in the rotor to surround an axis of the rotor; a swash
plate rotatably supported on an axis inclined with respect to the
axis of the rotor; and a rotary valve for controlling supply and
discharge of a working medium to and from an operating chamber
formed between a piston and a cylinder of the axial piston cylinder
group; a spherical projecting portion formed at a tip end of the
piston abutting against a spherical recessed portion annularly
disposed in the swash plate to surround the axis of the swash
plate; the rotor being rotationally driven by a reaction force
which the spherical projecting portion of the piston receives from
the spherical recessed portion of the swash plate, the piston
advancing by pressure of the working medium supplied to the
operating chamber, wherein a contact point at which the spherical
projecting portion of the piston presses the spherical recessed
portion of the swash plate is located on a cross line on which a
plane including a center of curvature of the spherical recessed
portion and the axis of the swash plate intersects the spherical
recessed portion.
2. The rotating fluid machine according to claim 1, wherein the
contact point at a moment when the working medium is supplied to
the operating chamber is located on the cross line.
3. The rotating fluid machine according to claim 2, wherein the
working medium is a compressible fluid.
4. The rotating fluid machine according to claim 1, wherein the
spherical projecting portion and the spherical recessed portion at
the contact point are prevented from slipping in the
circumferential direction and the radial direction.
5. The rotating fluid machine according to claim 4, wherein a phase
of the rotor and the swash plate are prevented from being displaced
to cause vibration, noise and abnormal abrasion and seizure due to
sliding friction and heat generation.
6. The rotating fluid machine according to claim 2, wherein at a
moment when the pressure of the working medium supplied from to the
operating chamber increases, slip between the spherical projecting
portion and the spherical recessed portion at the contact point is
prevented.
7. The rotating fluid machine according to claim 1, wherein the
contact point wherein the spherical projecting portion of the
piston abuts against the spherical recessed portion of the swash
plate is an arc-shaped cross line for preventing slipping
therebetween.
8. The rotating fluid machine according to claim 7, wherein a side
thrust is prevented from acting on the piston to avoid twisting and
sliding friction between the piston and the cylinder to avoid
abrasion and seizure.
9. The rotating fluid machine according to claim 1, wherein the
contact point is located on the cross line at the time of start of
an intake stroke of the piston.
10. The rotating fluid machine according to claim 1, wherein an
axis of the rotor is inclined at a predetermined angle relative to
the axis of the swash plate and wherein the piston cylinder group
are located on an oval to be equidistantly positioned to surround
the axis of the rotor.
11. A rotating fluid machine comprising: a rotor rotatably
supported within a casing; a plurality of pistons annularly
disposed in the rotor to surround an axis of the rotor; a swash
plate rotatably supported on an axis inclined with respect to the
axis of the rotor; and a rotary valve for controlling supply and
discharge of a working medium to and from an operating chamber
formed between a piston and a cylinder of each of the plurality of
pistons; a spherical projecting portion formed at a tip end of the
piston abutting against a spherical recessed portion annularly
disposed in the swash plate to surround the axis of the swash
plate; the rotor being rotationally driven by a reaction force
which the spherical projecting portion of the piston receives from
the spherical recessed portion of the swash plate, as each piston
advances in reaction to pressure of the working medium supplied to
the operating chamber, wherein a contact point at which the
spherical projecting portion of the piston presses the spherical
recessed portion of the swash plate is located on a cross line on
which a plane including a center of curvature of the spherical
recessed portion and the axis of the swash plate intersects the
spherical recessed portion.
12. The rotating fluid machine according to claim 11, wherein the
contact point at a moment when the working medium is supplied to
the operating chamber is located on the cross line.
13. The rotating fluid machine according to claim 12, wherein the
working medium is a compressible fluid.
14. The rotating fluid machine according to claim 11, wherein the
spherical projecting portion and the spherical recessed portion at
the contact point are prevented from slipping in the
circumferential direction and the radial direction.
15. The rotating fluid machine according to claim 14, wherein a
phase of the rotor and the swash plate are prevented from being
displaced to cause vibration, noise and abnormal abrasion and
seizure due to sliding friction and heat generation.
16. The rotating fluid machine according to claim 12, wherein at a
moment when the pressure of the working medium supplied from to the
operating chamber increases, slip between the spherical projecting
portion and the spherical recessed portion at the contact point is
prevented.
17. The rotating fluid machine according to claim 11, wherein the
contact point wherein the spherical projecting portion of the
piston abuts against the spherical recessed portion of the swash
plate is an arc-shaped cross line for preventing slipping
therebetween.
18. The rotating fluid machine according to claim 17, wherein a
side thrust is prevented from acting on the piston to avoid
twisting and sliding friction between the piston and the cylinder
to avoid abrasion and seizure.
19. The rotating fluid machine according to claim 11, wherein the
contact point is located on the cross line at the time of start of
an intake stroke of the piston.
20. The rotating fluid machine according to claim 11, wherein an
axis of the rotor is inclined at a predetermined angle relative to
the axis of the swash plate and wherein the plurality of pistons
are located on an oval to be equidistantly positioned to surround
the axis of the rotor.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present non-provisional application claims priority
under 35 USC 119 to Japanese Patent Application No. 2004-8813 filed
on Jan. 16, 2004 the entire contents thereof is hereby incorporated
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a rotating fluid machine in
which a rotary valve controls the supply and discharge of a working
medium to and from an operating chamber formed between a piston and
a cylinder of an axial piston cylinder group.
[0004] 2. Description of the Related Art
[0005] A rotating fluid machine for controlling the supply and
discharge of a working medium to and from an operating chamber is
disclosed in Japanese Patent Application Laid-open No. 2002-256805.
In this rotating fluid machine, a spherical projecting portion is
provided at a tip end of a piston of an axial piston cylinder group
disposed in a rotor, to abut against a spherical recessed portion
provided at a swash plate. When the piston is pushed out of the
cylinder by high-temperature high-pressure steam supplied to the
operating chamber, the spherical projecting portion of the piston
presses the spherical recessed portion of the swash plate, and the
reaction force which the piston receives from the swash plate
provides a rotational torque to the rotor.
[0006] If the high-temperature high-pressure steam is supplied to
the operating chamber at the time of the start of an intake stroke
to abruptly build up the pressure in the operating chamber so that
the piston is forcefully pushed out, the contact surface pressure
between the spherical projecting portion of the piston and the
spherical recessed portion of the swash plate abruptly rises,
leading to a possibility that the contact point between the
spherical projecting portion and the spherical recessed portion
slips in the circumferential direction, the radial direction and
the like of the swash plate. When the contact point between the
spherical projecting portion and the spherical recessed portion
slips, the phases of the rotor and the swash plate change and the
rotational angular speed of the rotor suddenly changes to cause
vibration and noise. Moreover, a large side thrust acts on the
piston and heat due to a twisting and sliding friction that occurs
between the piston and the cylinder, causing abnormal friction and
seizure.
SUMMARY OF THE INVENTION
[0007] The present invention has been achieved in view of the above
circumstances, and has its object to prevent slip of a contact
point between a spherical projecting portion of a piston and a
spherical recessed portion of a swash plate of a rotating fluid
machine.
[0008] In order to attain the above-described object, according to
a first feature of the present invention, there is provided a
rotating fluid machine with a casing, a rotor rotatably supported
by the casing and an axial piston cylinder group annularly disposed
in the rotor to surround an axis of the rotor. A swash plate is
provided that is rotatably supported on an axis inclined with
respect to the axis of the rotor with a rotary valve which controls
the supply and discharge of a working medium to and from an
operating chamber formed between a piston and a cylinder of the
axial piston cylinder group. A spherical projecting portion is
formed at a tip end of the piston abutting against a spherical
recessed portion that is annularly disposed in the swash plate to
surround the axis of the swash plate. The rotor is rotationally
driven by a reaction force which the spherical projecting portion
of the piston receives from the spherical recessed portion of the
swash plate with the piston advancing by pressure of the working
medium supplied to the operating chamber. A contact point at which
the spherical projecting portion of the piston presses the
spherical recessed portion of the swash plate is located on a cross
line on which a plane including a center of curvature of the
spherical recessed portion and the axis of the swash plate
intersects the spherical recessed portion.
[0009] According to a second feature of the present invention, the
contact point at a moment when the working medium is supplied to
the operating chamber is located on the cross line.
[0010] According to a third aspect of the invention, the working
medium is a compressible fluid.
[0011] With the arrangement of the first feature, the contact point
of the spherical projecting portion of the piston presses the
spherical recessed portion of the swash plate that is located on
the cross line on which the plane including the center of curvature
of the spherical recessed portion and the axis of the swash plate
intersects the spherical recessed portion. Therefore, even if the
piston forcefully presses the swash plate, the spherical projecting
portion and the spherical recessed portion at the contact point are
prevented from slipping in the circumferential direction, the
radial direction and the like, and the phases of the rotor and the
swash plate are prevented from being displaced to cause vibration,
noise, and abnormal abrasion and seizure due to slide friction and
heat generation, and the like.
[0012] With the arrangement of the second feature, the contact
point at the moment when the working medium is supplied to the
operating chamber is located on the cross line, and therefore at
the moment when the pressure of the operating chamber abruptly
rises, namely, when the spherical projecting portion of the piston
and the spherical recessed portion of the swash plate are most
likely to slip at the contact point, the slip is reliably prevented
to provide smooth rotation of the rotor.
[0013] With the arrangement of the third feature, the working
medium is a compressible fluid. Therefore, even if the pressure
impulsively rises at the moment when the working medium is supplied
to the operating chamber, the spherical projecting portion and the
spherical recessed portion at the contact point are prevented from
slipping, to thereby ensure smooth rotation of the rotor.
[0014] Further scope of applicability of the present invention will
become apparent from the detailed description given hereinafter.
However, it should be understood that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the
invention will become apparent to those skilled in the art from
this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The present invention will become more fully understood from
the detailed description given herein below and the accompanying
drawings which are given by way of illustration only, and thus are
not limitative of the present invention, and wherein:
[0016] FIG. 1 is a longitudinal sectional view of an expander;
[0017] FIG. 2 is an enlarged view of the section 2 in FIG. 1
(sectional view taken along the line 2-2 in FIG. 6);
[0018] FIG. 3 is an exploded perspective view of a rotor;
[0019] FIG. 4 is a view seen along the arrowed line 4-4 in FIG.
2;
[0020] FIG. 5 is a graph showing pressure fluctuation of an
operating chamber with respect to a rotational angle of the
rotor;
[0021] FIG. 6 is a view seen along the line 6-6 in FIG. 2;
[0022] FIGS. 7A and 7B are views showing loci of contact points of
five pistons; and
[0023] FIG. 8 is a view corresponding to FIG. 4, according to a
second embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0024] As shown in FIG. 1 to FIG. 3, an expander E of this
embodiment is used in, for example, a Rankine cycle system. The
expander E converts the thermal energy and the pressure energy of
high-temperature high-pressure steam as a working medium into
mechanical energy that is outputted. A casing 11 of the expander E
is formed from a casing body 12 with a front cover 15 joined via a
seal 13 to a front opening of the casing body 12 by a plurality of
bolts 14. A rear cover 18 is joined via a seal 16 to a rear opening
of the casing body 12 by a plurality of bolts 17, and an oil pan 21
is joined via a seal 19 to a lower opening of the casing body 12 by
a plurality of bolts 20.
[0025] A rotor 22 is arranged rotatably around an axis Lr and
extends in the fore-and-aft direction through the center of the
casing 11 with a front part supported by combined angular bearings
23 provided in the front cover 15, and a rear part thereof
supported by a radial bearing 24 provided in the casing body 12. A
swash plate holder 28 is formed integrally with a rear face of the
front cover 15. A swash plate 31 is rotatably supported by the
swash plate holder 28 via an angular bearing 30. The axis Ls of the
swash plate 31 is inclined relative to the axis Lr of the rotor 22,
and the angle of inclination is fixed.
[0026] The rotor 22 includes an output shaft 32 supported in the
front cover 15 by the combined angular bearings 23 with three
sleeve support flanges 33, 34, and 35 formed integrally with a rear
part of the output shaft 32. A rotor head 38 is joined by a
plurality of bolts 37 to the rear sleeve support flange 35 via a
metal gasket 36 and is supported in the casing body 12 by the
radial bearing 24. A heat-insulating cover 40 is fitted over the
three sleeve support flanges 33, 34, and 35 from the front and
joined to the front sleeve support flange 33 by a plurality of
bolts 39.
[0027] Sets of five sleeve support holes 33a, 34a, and 35a are
formed in the three sleeve support flanges 33, 34, and 35
respectively at intervals of 72.degree. around the axis Lr. Five
cylinder sleeves 41 are fitted into the sleeve support holes 33a,
34a, and 35a from the rear. A flange 41a is formed on the rear end
of each of the cylinder sleeves 41, and axial positioning is
carried out by abutting this flange 41a against the metal gasket 36
while fitting the flange 41a into a step 35b formed in the sleeve
support holes 35a of the rear sleeve support flange 35. A piston 42
is slidably fitted in an inside of each of the cylinders 41 with
the spherical projecting portion 42a formed at a tip end of the
piston 42 abutting against a spherical recessed portion 31a formed
on the swash plate 31. An operating chamber 43 for steam is defined
between the rear end of the piston 42 and the rotor head 38.
[0028] As is obvious from FIG. 1, FIG. 2 and FIG. 4, a steam supply
pipe 85 is disposed on the axis Lr of the rotor 22, and a steam
discharge pipe 89 is disposed eccentrically outwardly in a radial
direction of the steam supply pipe 85. A rotary valve 71 includes a
fixed side valve plate 73 fixed to the casing 11 and a movable side
valve plate 74 fixed to the rotor 22, which slidably abut against
each other on a slide surface 77. A first steam passage P1 (see
FIG. 1) is formed inside the steam supply pipe 85 and communicates
with a circular second steam passage P2 opening to the slide
surface 77. An arc-shaped fifth steam passage P5 opening to the
slide surface 77 communicates with the steam discharge pipe 89. In
the movable side valve plate 74, five third steam passages P3
communicable with the second steam passage P2 and the fifth steam
passage P5 on the slide surface 77 are equidistantly disposed to
surround the axis Lr. The five third steam passages P3 respectively
communicate with five operating chambers 43 via five fourth steam
passages P4 which penetrate through the rotor head 38.
[0029] As is obvious from FIG. 4, the circular second steam passage
P2 (shown by the chain line) and the arc-shaped fifth steam passage
P5 (shown by the chain line) formed in the fixed side valve plate
73, and one of the five third steam passages P3 (shown by the solid
line) opening to the movable side valve plate 74, open to the slide
surface 77 between the fixed side valve plate 73 and the movable
side valve plate 74. The rotational direction of the movable side
valve plate 74 which rotates with the rotor 22 is shown by the
arrow. The third steam passage P3 communicates with the second
steam passage P2 at the same time when the third steam passage P3
is shut off from communication with the fifth steam passage P5 at a
position P3 (1) with an angle .alpha. before the top dead center.
The third steam passage P3 is shut off from communication with the
second steam passage P2 at a position P3 (2) which is past the top
dead center TDC by the angle .alpha., and the intake stroke is
performed from the position P3 (1) to the position P3 (2). The
third steam passage P3 communicates with the fifth steam passage P5
at a position P3 (3) with an angle .beta. before a bottom dead
center BDC. An expansion stroke is performed from the position P3
(2) to the position P3 (3), and an exhaust stroke is performed from
the position P3 (3) to the position P3 (1).
[0030] FIG. 5 shows the pressure change in the operating chamber 43
with respect to the rotational angle of the rotor 22 with the top
dead center as the reference. In the intake stroke which begins
from the position with the angle a before the top dead center and
finishes at the position past the top dead center by the angle a,
the second steam passage P2 communicates with the third steam
passage P3 to increase the pressure at a dash. In the subsequent
expansion stroke, the high-temperature high-pressure steam expands
in the operating chamber 43 which is hermetically sealed, whereby
the pressure gradually decreases, so that the high-temperature
high-pressure steam becomes the low-temperature low-pressure steam.
In the subsequent exhaust stroke, the operating chamber 43 is
opened to reduce the pressure, so that the pressure becomes
substantially the same pressure as that in the inner pressure of
the condenser (substantially the atmospheric pressure).
[0031] FIG. 6 is the view of the swash plate 31 seen in a direction
of its axis Ls, with the center of curvatures O of five spherical
recessed portions 31a being equidistantly located on a circle with
the axis Ls of the swash plate 31 as the center. Meanwhile, the
axis Lr of the rotor 22 is inclined by the angle .theta. with
respect to the axis Ls of the swash plate 31, and therefore the
axes Lp of the five pistons 42 which are equidistantly placed to
surround the axis Lr of the rotor 22 are located on an oval. At the
start of the intake stroke, a contact point CP at which the
spherical projecting portion 42a of the piston 42 abuts against the
spherical recessed portion 31a of the swash plate 31 is located on
a cross line CL on which a plane P including the center of
curvature O of the spherical recessed portion 31a and the axis Ls
of the swash plate 31 intersects the spherical recessed portion
31a.
[0032] Next, the operation of the expander E of the present
embodiment with the above-described construction will be
described.
[0033] The high-temperature high-pressure steam generated by
heating water by a vaporizer passes through the first steam passage
P1 in the steam supply pipe 85 and the second steam passage P2 of
the fixed side valve plate 73, to reach the slide surface 77 of the
movable side valve plate 74. The second steam passage P2 which
opens to the slide surface 77 instantly communicates, in a
predetermined timing, with the five third steam passages P3 formed
in the movable side valve plate 74 which rotates integrally with
the rotor 22, so that the high-temperature high-pressure steam
passes from the third steam passage P3 through the fourth steam
passage P4 formed in the rotor 22, to be supplied to the expansion
chamber 43 in the cylinder sleeve 41.
[0034] Even after the communication between the second steam
passage P2 and the third steam passage P3 is shut off with the
rotation of the rotor 22, the high-temperature high-pressure steam
expands in the expansion chamber 43, whereby the piston 42 fitted
in the cylinder sleeve 41 is pushed forward from the top dead
center to the bottom dead center, and the front end of the piston
42 presses the dimple 31a of the swash plate 31. As a result, a
rotation torque is given to the rotor 22 due to the reaction force
which the piston 42 receives from the swash plate 31. Thus, every
time the rotor 22 makes one-fifth of a turn, the high-temperature
high-pressure steam is supplied into a new adjacent expansion
chamber 43, thereby continuously driving the rotor 22 to
rotate.
[0035] While the piston 42 having reached the bottom dead center
with the rotation of the rotor 22 retreating to the top dead center
by being pressed by the swash plate 31, the low-temperature
low-pressure steam pushed out of the expansion chamber 43 is
supplied to a condenser via the fourth steam passage P4 of the
rotor 22, the third steam passage P3 of the movable side valve
plate 74, the slide surface 77, the fifth steam passage P5, and the
steam discharge pipe 89.
[0036] As explained in FIG. 5, when the pressure of the operating
chamber 43 rises abruptly and the piston 42 is forcefully pushed
out at the start of the intake stroke, the contact surface pressure
between the spherical projecting portion 42a of the piston 42 and
the spherical recessed portion 31a of the swash plate 31 abruptly
rises, leading to the problem that the contact point CP between the
spherical projecting portion 42a and the spherical recessed portion
31a slips in the circumferential direction, so that the rotational
angular speed of the rotor 22 suddenly changes to cause vibration
and noise. But, in the present embodiment, however forcefully the
spherical projecting portion 42a of the piston 42 may press the
spherical recessed portion 31a of the swash plate 31, the spherical
projecting portion 42a and the spherical recessed portion 31a are
prevented from slipping at the contact point CP, and the phases of
the rotor 2 and the swash plate 31 are prevented from changing due
to the slip, because the contact point CP at which the spherical
projecting portion 42a of the piston 42 abuts against the spherical
recessed portion 31a of the swash plate 31, is located on the
arc-shaped cross line CL on which the plane P including the center
of curvature O of the spherical recessed portion 31a and the axis
Ls of the swash plate 31 intersects the spherical recessed portion
31a. As a result, the rotational angular speed of the rotor 22 is
prevented from changing and causing vibration and noise, and a
large side thrust is prevented from acting on the piston 42 and
causing heat due to a twisting and sliding friction between the
piston 42 and the cylinder 41 to cause abnormal abrasion and
seizure.
[0037] It is only at the time of start of the intake stroke that
the contact point CP needs to be located on the cross line CL on
which the plane P including the center of curvature O of the
spherical recessed portion 31a and the axis Ls of the swash plate
31 intersects the spherical recessed portion 31a, and in the other
occasions, the contact point CP is out of the cross line CL.
However, it is at the start time of the intake stroke when an
impactive load is applied, that the spherical projecting portion
42a and the spherical recessed portion 31a are most likely to slip,
and therefore a sufficient effect can be obtained.
[0038] FIGS. 7A and 7B each show the loci of movement of the
contact points CP of the spherical projecting portions 42a of the
five pistons 42 by five arrows. It is understood that in the prior
art shown in FIG. 7A, every time the rotor 22 rotates 72.degree.
and the intake stroke is started, the spherical projecting portion
42a and the spherical recessed portion 31a slip at the contact
point CP, so that the movement loci of the contact points CP are
discontinuous. On the other hand, in the embodiment shown in FIG.
7B, the spherical projecting portions 42a and the spherical
recessed portions 31a are prevented from slipping, so that the
movement loci of the contact points CP become continuous.
[0039] Next, a second embodiment of the present invention will be
described. The rotating fluid machine of the first embodiment is an
expander E using the compressible fluid as the working medium, but
a rotating fluid machine of the second embodiment is a hydraulic
motor using an incompressible fluid as the working medium.
[0040] As shown in FIG. 8, a second oil port P2' which is an intake
port and a fifth oil port P5' which is a discharge port, are formed
symmetrically with the top dead center TDC and the bottom dead
center BDC therebetween. Accordingly, a third oil port P3' leading
to the operating chamber 43 communicates with the second oil port
P2' from a position P3' (1) past the top dead center TDC by an
angle .gamma. to a position P3' (2) with the angle .gamma. before
the bottom dead center BDC, during which the intake stroke is
performed. As shown by the chain line in FIG. 5, the pressure of
the operating chamber 43 that abruptly rises at the same time as
the start of the intake stroke, is then kept at a fixed value, and
abruptly lowers at the same time as the termination of the intake
stroke.
[0041] In the second embodiment, at the time of start of the intake
stroke when the pressure of the operating chamber 43 abruptly
rises, namely, at the position P3' (1) past the top dead center TDC
by the angle .gamma., the contact point CP at which the spherical
projecting portion 42a of the piston 42 abuts against the spherical
recessed portion 31a of the swash plate 31 is located on the cross
line CL on which the plane P including the center of curvature O of
the spherical recessed portion 31a and the axis Ls of the swash
plate 31 intersects the spherical recessed portion 31a. As a
result, when the pressure of the operating chamber 43 abruptly
rises with the start of the intake stroke, the spherical projecting
portion 42a and the spherical recessed portion 31a at the contact
point CP are prevented from slipping in the circumferential
direction, the radial direction and the like, and the rotational
angular speed of the rotor 22 is prevented from changing and
causing vibration, noise, abnormal abrasion and the like.
[0042] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
following claims.
[0043] For example, the time at which the contact point CP is
located on the cross line CL is set at the time of the start of the
intake stroke in the first embodiment as well as in the second
embodiment, but it can be set at an optional time when the piston
42 presses the swash plate 31.
[0044] The spherical projecting portion 42a and the spherical
recessed portion 31a do not need to have a strict spherical
surface, and they may have any spherical surface as long as the
spherical surface is formed by rotating a line about an axis.
* * * * *