U.S. patent application number 11/560268 was filed with the patent office on 2007-05-24 for control device for a vehicular refrigeration, vehicular variable displacement compressor, and a control valve for the vehicular variable displacement compressor.
This patent application is currently assigned to Kabushiki Kaisha Toyota Jidoshokki. Invention is credited to Tetsuhiko Fukanuma, Naoya Yokomachi.
Application Number | 20070116578 11/560268 |
Document ID | / |
Family ID | 37500444 |
Filed Date | 2007-05-24 |
United States Patent
Application |
20070116578 |
Kind Code |
A1 |
Fukanuma; Tetsuhiko ; et
al. |
May 24, 2007 |
Control Device for a Vehicular Refrigeration, Vehicular Variable
Displacement Compressor, and A Control Valve for the Vehicular
Variable Displacement Compressor
Abstract
Provided is a control valve of a vehicular refrigeration
circuit, including: an air supply passage for communicating a
discharge chamber and a crank chamber with each other; a second rod
capable of changing a primary opening which is the degree of
opening of the air supply passage; a first bellows which moves
while causing a first load F1 due to a differential pressure
.DELTA.Pd between a high discharge pressure PdH and a low discharge
pressure PdL to operate the second rod such that the primary
opening increases or decreases; a constant pressure valve for
maintaining the low discharge pressure PdL in a high pressure
chamber communicating with the discharge chamber at a constant
correction pressure PdL0; an actuator capable of changing the
correction pressure PdL0 to a predetermined control pressure PdLx
due to energization control by a controller; and a second bellows
which moves while causing a second load F2 opposing the first load
F1 with the control pressure PdLx to adjust the primary
opening.
Inventors: |
Fukanuma; Tetsuhiko;
(Kariya-shi, JP) ; Yokomachi; Naoya; (Kariya-shi,
JP) |
Correspondence
Address: |
WOODCOCK WASHBURN LLP
CIRA CENTRE, 12TH FLOOR
2929 ARCH STREET
PHILADELPHIA
PA
19104-2891
US
|
Assignee: |
Kabushiki Kaisha Toyota
Jidoshokki
Kariya-shi
JP
|
Family ID: |
37500444 |
Appl. No.: |
11/560268 |
Filed: |
November 15, 2006 |
Current U.S.
Class: |
417/222.2 |
Current CPC
Class: |
F04B 2027/1854 20130101;
F04B 2027/185 20130101; F04B 27/1804 20130101; F04B 2027/1827
20130101; F04B 2027/1813 20130101 |
Class at
Publication: |
417/222.2 |
International
Class: |
F04B 1/26 20060101
F04B001/26 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 16, 2005 |
JP |
2005-331918 |
Claims
1. A control device for a vehicular refrigeration circuit used
together with a variable displacement compressor, having a crank
chamber, an intake chamber, and a discharge chamber, in which
discharge capacity can be changed by controlling a pressure of the
crank chamber, and with an exterior refrigerant circulation circuit
connected to the intake chamber and the discharge chamber of the
variable displacement compressor, the control device comprising: a
bleed passage for communicating the intake chamber and the crank
chamber with each other; an air supply passage for communicating
the discharge chamber and the crank chamber with each other; a
primary valve mechanism capable of changing a primary opening which
is a degree of opening of at least one of the bleed passage and the
air supply passage; a first pressure sensing member which moves
while causing a first load due to a state pressure which is a
pressure having a factor for controlling the discharge capacity to
operate the primary valve mechanism so that the primary opening
increases or decreases; a constant pressure valve mechanism for
maintaining a high pressure in a high pressure chamber, which
communicates with the discharge chamber, to be a constant
correction pressure; a secondary valve mechanism capable of
changing the correction pressure to a predetermined control
pressure by external energization control; and a second pressure
sensing member which moves while causing due to the control
pressure a second load opposing the first load to correct the
primary opening.
2. A control device for a vehicular refrigeration circuit according
to claim 1, further comprising: a state pressure chamber
communicating with the discharge chamber through a state pressure
passage; and a differential pressure generating mechanism provided
in the state pressure passage, for causing the state pressure to be
turned into a first state pressure and a second state pressure
having a difference therebetween, wherein the first pressure
sensing member is provided in the state pressure chamber, and moves
due to a differential pressure between the first state pressure and
the second state pressure while causing the first load.
3. A control device for a vehicular refrigeration circuit according
to claim 2, wherein: the state pressure chamber is a first pressure
sensing chamber which accommodates the first pressure sensing
member, to which one of the first state pressure and the second
state pressure is introduced, and which constitutes a part of the
air supply passage; and the first pressure sensing member is a
bellows which includes therein a first control chamber to which the
other of the first state pressure and the second state pressure is
introduced.
4. A control device for a vehicular refrigeration circuit according
to claim 1, further comprising a second pressure sensing chamber
accommodating the second pressure sensing member and constituting a
part of the air supply passage, wherein the second pressure sensing
member is a bellows including therein a second control chamber to
which the control pressure is introduced.
5. A control device for a vehicular refrigeration circuit according
to claim 1, wherein the secondary valve mechanism comprises: a high
pressure passage for communicating the discharge chamber and the
second control chamber with each other; a release passage for
communicating the second control chamber and the air supply passage
with each other; and an actuator operated by controlling
energization with respect thereto from outside and capable of
changing a secondary opening which is a degree of opening of the
release passage.
6. A control device for a vehicular refrigeration circuit according
to claim 1, wherein the secondary valve mechanism comprises: a high
pressure passage for communicating the discharge chamber and the
second control chamber with each other; and an actuator operated by
controlling energization with respect thereto from outside and
capable of changing a secondary opening which is a degree of
opening of the high pressure passage.
7. A control device for a vehicular refrigeration circuit according
to claim 5, wherein the actuator comprises a piezoelectric
element.
8. A control device for a vehicular refrigeration circuit according
to claim 7, further comprising a controller for controlling a duty
ratio of a voltage to be applied to the piezoelectric element.
9. A variable displacement compressor, comprising: a housing
including a cylinder bore, a crank chamber, an intake chamber, and
a discharge chamber formed therein; a piston reciprocatingly
accommodated in the cylinder bore, for defining a compression
chamber in the cylinder bore; a drive shaft driven by an exterior
drive source and rotatably supported by the housing; a swash plate
supported in the crank chamber so that the swash plate can rotate
in synchronism with the drive shaft and can be inclined, for
allowing the piston to be reciprocatingly driven; and a control
mechanism for controlling a pressure in the crank chamber, capable
of changing an inclination angle of the swash plate to change a
discharge capacity, the intake chamber and the discharge chamber
being connected to an exterior refrigerant circulation circuit to
constitute a vehicular refrigeration circuit, wherein the control
mechanism is the control device according to claim 1.
10. A control valve for the variable displacement compressor
according to claim 9, comprising: a valve housing fixed to the
housing; the air supply passage and the high pressure chamber
formed in the valve housing; and the primary valve mechanism, the
first pressure sensing member,the constant pressure valve
mechanism, the secondary valve mechanism, and the second pressure
sensing member provided in the valve housing.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a control device for a
vehicular refrigeration circuit, a variable displacement
compressor, and a control valve for the variable displacement
compressor.
BACKGROUND OF THE INVENTION
[0002] JP 03-43685 A discloses a conventional variable displacement
compressor. The variable displacement compressor includes a crank
chamber, an intake chamber, and a discharge chamber, in which
discharge capacity can be changed by controlling pressure of the
crank chamber.
[0003] In the variable displacement compressor, the intake chamber
is connected to an evaporator through tubing, the evaporator is
connected to an expansion valve through the tubing, the expansion
valve is connected to a condenser through the tubing, and the
condenser is connected to the discharge chamber of the variable
displacement compressor. With this construction, the variable
displacement compressor may be used together with an exterior
refrigerant circulation circuit composed of the evaporator, the
expansion valve, the condenser, and the tubing, and may constitute
a refrigeration circuit for a vehicle or the like.
[0004] In the variable displacement compressor, the intake chamber
and the crank chamber communicate with each other through a bleed
passage, and the discharge chamber and the crank chamber
communicate with each other through an air supply passage. Further,
the variable displacement compressor includes a first control
device and a second control device built therein. The first control
device and the second control device are control devices used for
the refrigeration circuit which is used together with the variable
displacement compressor and the exterior refrigerant circulation
circuit.
[0005] The first control device includes a primary valve mechanism
capable of changing a primary opening which is the degree of
opening of the bleed passage, and a bellows provided in the bleed
passage. The bellows moves in an axial direction while causing a
first load due to the pressure of the crank chamber. The primary
opening of the bleed passage decreases when the pressure of the
crank chamber is higher than a set pressure and increases when the
pressure of the crank chamber is lower than the set pressure.
[0006] Further, the first control device includes an intermediate
chamber communicating with the discharge chamber through a fixed
restriction and an actuating rod extending from the discharge
chamber through the intermediate chamber to a valve body of the
primary valve mechanism. The actuating rod has a small diameter
portion on the discharge chamber side and a large diameter portion
on the primary valve mechanism side, the large diameter portion
being larger in diameter than the small diameter portion. An end of
the small diameter portion of the actuating rod is exposed to the
discharge chamber and a middle portion thereof faces the
intermediate chamber. The discharge chamber and the intermediate
chamber communicate with each other through the fixed restriction
formed of a gap between the actuating rod and an axial hole of a
valve cylinder for accommodating the actuating rod. Further,
provision of the axial hole enables the intermediate chamber to
allow pressure to act on the large diameter portion of the
actuating rod. Thus, the actuating rod moves in the axial direction
while causing a second load opposing the first load with the
pressure of the discharge chamber and the pressure of the
intermediate chamber, and adjust the primary valve mechanism so
that the primary opening decreases or increases.
[0007] The second control device includes an electromagnetic flow
control valve capable of varying the pressure of the intermediate
chamber. The electromagnetic flow control valve is provided in a
communication passage for allowing the intermediate chamber and the
intake chamber to communicate with each other. The electromagnetic
flow control valve can change a secondary opening, that is, the
degree of opening of the communicating passage, due to an
energization control from the outside, thereby changing the
pressure of the intermediate chamber.
[0008] In the refrigeration circuit structured as described above,
since the pressure of the crank chamber is a pressure with a factor
for controlling the discharge capacity, the bellows of the first
control device appropriately moves due to the pressure of the crank
chamber, and the primary valve mechanism changes the primary
opening of the bleed passage. As a result, this determines the
pressure of the crank chamber primarily.
[0009] Further, the second control device changes the pressure of
the intermediate chamber through the energization control. The
actuating rod of the second control device appropriately moves due
to the pressure of the discharge chamber and the pressure of the
intermediate chamber. Thus, the actuating rod adjusts the primary
valve mechanism so that the primary opening of the bleed passage
decreases or increases. As a result, the pressure of the crank
chamber is determined secondarily.
[0010] In this manner, the discharge capacity of the variable
displacement compressor is changed. This refrigeration circuit is
aimed at obtaining precise air conditioning according to the
driving state of the variable displacement compressor, the outside
environment, and the like.
[0011] However, the above-mentioned refrigeration circuit allows
the pressure of the discharge chamber to act on the actuating rod
as it is. The pressure of the discharge chamber naturally
fluctuates according to the driving state of the variable
displacement compressor, the outside environment, or the like.
Therefore, in this refrigeration circuit, the actuating rod can
resist the first load of the bellows too much or not resist it
enough, so the pressure of the crank chamber may not be maintained
in an optimum state.
[0012] The refrigeration circuit also allows the pressure of the
intermediate chamber to act on the actuating rod and allows the
pressure of the intermediate chamber to be changed through
energization control from the outside by the electromagnetic flow
control valve. Thus, it is felt that this refrigeration circuit is
aimed at solving malfunctions due to fluctuations in the pressure
of the discharge chamber by the energization control.
[0013] However, in this refrigeration circuit, when an attempt is
made to solve malfunctions due to fluctuations of the pressure of
the discharge chamber, the energization control must be performed
in response to unsteady discharge pressure, so control by using a
controller becomes complicated. In particular, in this
refrigeration circuit, the pressure of the intermediate chamber
itself, which is changed by the energization control, is affected
by the pressure of the discharge chamber to fluctuate, so control
by using the controller becomes more complicated.
[0014] Thus, this refrigerator circuit involves considerable
difficulties in truly performing precise air conditioning according
to a driving state of the variable displacement compressor, the
outside environment, and the like.
SUMMARY OF THE INVENTION
[0015] The present invention has been made in view of the
above-mentioned conventional problems. An object to be solved by
the present invention is therefore the relatively easy realization
of precise air conditioning according to the driving state of the
variable displacement compressor, the outside environment, and the
like.
[0016] According to the present invention, a control device for a
vehicular refrigeration circuit is used together with a variable
displacement compressor, having a crank chamber, an intake chamber
and a discharge chamber, in which discharge capacity can be changed
by controlling a pressure of the crank chamber, and with an
exterior refrigerant circulation circuit connected to the intake
chamber and the discharge chamber of the variable displacement
compressor.
[0017] The control device is characterized by including: a bleed
passage for communicating the intake chamber and the crank chamber
with each other; an air supply passage for communicating the
discharge chamber and the crank chamber with each other; a primary
valve mechanism capable of changing a primary opening which is the
degree of opening of at least one of the bleed passage and the air
supply passage; a first pressure sensing member which moves while
causing a first load due to a state pressure which is a pressure
having a factor for controlling the discharge capacity and operates
the primary valve mechanism so that the primary opening increases
or decreases; a constant pressure valve mechanism for maintaining a
high pressure in a high pressure chamber communicated with the
discharge chamber, at a constant correction pressure; a secondary
valve mechanism capable of changing the correction pressure to a
predetermined control pressure by external energization control;
and a second pressure sensing member which moves while causing a
second load opposing the first load with the control pressure to
correct the primary opening.
[0018] The primary valve mechanism may also be capable of changing
the primary opening which is the degree of opening of the bleed
passage, of changing the primary opening which is the degree of
opening of the air supply passage, or of changing the primary
opening which is the degree of opening of both the bleed passage
and the air supply passage.
[0019] The first pressure sensing member moves due to a state
pressure. The state pressure is a pressure having a factor for
controlling the discharge capacity. As the state pressure, it is
possible to adopt the intake pressure, for example, inside the
intake chamber or in a low pressure portion of the exterior
refrigerant circulation circuit, the discharge pressure, for
example, of the discharge chamber or in a high pressure portion the
exterior refrigerant circulation circuit, the differential pressure
between the discharge pressures, or the like. As the first pressure
sensing member, it is possible to adopt a bellows, a diaphragm, a
rod, or the like.
[0020] As the constant pressure valve mechanism, a pressure
regulating valve of a known constant pressure valve (i.e., pressure
reducing valve) or the like may be adopted. Note that, the high
pressure chamber may be directly connected to the discharge chamber
or may be indirectly connected to the discharge chamber so as to be
directly connected to the high pressure portion of the exterior
refrigerant circulation circuit or the like.
[0021] As the secondary valve mechanism, it is possible to adopt a
piezoelectric element, an electromagnetic opening/closing valve, or
the like.
[0022] The second pressure sensing member moves due to the control
pressure. As the second pressure sensing member, it is also
possible to adopt a bellows, a diaphragm, a rod, or the like. In a
case where a bellows is adopted as the second pressure sensing
member, the control pressure may be introduced into a chamber
accommodating the bellows or may be introduced into the
bellows.
[0023] The control device according to the present invention may
comprise: a state pressure chamber communicating with the discharge
chamber through a state pressure passage; and a differential
pressure generating mechanism provided in the state pressure
passage, for causing the state pressure to be turned into a first
state pressure and a second state pressure having a difference
therebetween, wherein the first pressure sensing member is provided
in the state pressure chamber, and moves due to a differential
pressure between the first state pressure and the second state
pressure while causing the first load.
[0024] In this case, the differential pressure between the
discharge pressures is the state pressure. The larger the flow rate
of the refrigerant flowing through the exterior refrigerant
circulation circuit becomes, the larger the pressure loss per unit
length of the exterior refrigerant circulation circuit. Therefore,
when the first pressure sensing member moves due to the
differential pressure between the first state pressure and the
second state pressure, the discharge capacity is determined while
taking into consideration the flow rate of the refrigerant flowing
through the exterior refrigerant circulation circuit.
[0025] When a bellows is adopted as the first pressure sensing
member, the primary valve mechanism can be operated at high
precision by the state pressure. Further, the movement is limited
to the axial direction, so the direction of the first load is also
limited to the axial direction, thus the first load can oppose the
second load in a favorable manner.
[0026] The control device according to the present invention may
comprise a second pressure sensing chamber accommodating the second
pressure sensing member and constituting a part of the air supply
passage, wherein the second pressure sensing member is a bellows
including therein a second control chamber to which the control
pressure is introduced.
[0027] In the control device according to the present invention,
the secondary valve mechanism may comprise: a high pressure passage
for communicating the discharge chamber and the second control
chamber with each other; a release passage for communicating the
second control chamber and the air supply passage with each other;
and an actuator operated by controlling energization with respect
thereto from outside and capable of changing a secondary opening
which is the degree of opening of the release passage.
[0028] In the control device according to the present invention,
the secondary valve mechanism may comprise: a high pressure passage
for communicating the discharge chamber and the second control
chamber with each other; and an actuator operated by controlling
energization with respect thereto from outside and capable of
changing a secondary opening which is the degree of opening of the
high pressure passage.
[0029] It is preferable that the actuator is formed of a
piezoelectric element because, with such construction, it is
possible to achieve downsizing of the actuator and to easily change
the secondary opening due to energization control from the
outside.
[0030] The control device according to the present invention
preferably includes a controller for controlling a duty ratio of a
voltage to be applied to the piezoelectric element. The reason for
this is that the provision of the controller facilitates
energization control with respect to the piezoelectric element
according to the driving state of the variable displacement
compressor, the exterior environment, and the like.
[0031] The variable displacement compressor according to the
present invention comprises: a housing including a cylinder bore, a
crank chamber, an intake chamber, and a discharge chamber formed
therein; a piston reciprocatingly accommodated in the cylinder
bore, for defining a compression chamber in the cylinder bore; a
drive shaft driven by an exterior drive source and rotatably
supported by the housing; a swash plate supported in the crank
chamber so that the swash plate can rotate in synchronism with the
drive shaft and can be inclined, for allowing the piston to be
reciprocatingly driven; and a control mechanism for controlling a
pressure in the crank chamber, capable of changing an inclination
angle of the swash plate to change discharge capacity, the intake
chamber and the discharge chamber being connected to an exterior
refrigerant circulation circuit to constitute a vehicular
refrigeration circuit, wherein the control mechanism is the control
device according to the present invention.
[0032] By using the variable displacement compressor for the
vehicular refrigeration circuit, it is relatively easy to realize
precise air conditioning according to the driving state of the
vehicle, the outside environment, and the like.
[0033] The control valve for the variable displacement compressor
according to the present invention comprises: a valve housing fixed
to the housing; the air supply passage and the high pressure
chamber formed in the valve housing; and the primary valve
mechanism, the first pressure sensing member, the constant pressure
valve mechanism, the secondary valve mechanism, and the second
pressure sensing member provided in the valve housing.
[0034] As the control valve is integral with the variable
displacement compressor, by using the variable displacement
compressor for the vehicular refrigeration circuit, it is possible
to obtain the above-mentioned operational effects.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 is a schematic sectional view of a part of a variable
displacement compressor or the like of a vehicular refrigeration
circuit according to Embodiment 1 of the present invention;
[0036] FIG. 2 is a sectional view of a control valve of the
vehicular refrigeration circuit according to Embodiment 1;
[0037] FIG. 3 is an enlarged sectional view of a main part of the
control valve of the vehicular refrigeration circuit according to
Embodiment 1;
[0038] FIG. 4 is a block diagram of a control system of the
vehicular refrigeration circuit according to Embodiment 1;
[0039] FIG. 5 is a graph showing a relationship between time and a
discharge pressure of the vehicular refrigeration circuit according
to Embodiment 1;
[0040] FIG. 6 is a graph showing a control property of a controller
of the vehicular refrigeration circuit according to Embodiment
1;
[0041] FIG. 7 is a schematic view of a main part of the control
valve of the vehicular refrigeration circuit according to
Embodiment 1;
[0042] FIG. 8 is an enlarged sectional view of a main part of a
control valve of a vehicular refrigeration circuit according to
Embodiment 2 of the present invention;
[0043] FIG. 9 is a schematic view of a main part of the control
valve of the vehicular refrigeration circuit according to
Embodiment 2;
[0044] FIG. 10 is a graph showing a control property of a
controller of the vehicular refrigeration circuit according to
Embodiment 2;
[0045] FIG. 11 is a schematic view of a main part of a control
valve of a vehicular refrigeration circuit according to a
modification of the present invention; and
[0046] FIG. 12 is a schematic view of a main part of a control
valve of a vehicular refrigeration circuit according to another
modification of the present invention.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0047] Hereinafter, Embodiments 1 and 2 of the present invention
will be described with reference to the drawings.
Embodiment 1
[0048] As shown in FIG. 1, a vehicular refrigeration circuit
according to Embodiment 1 of the present invention includes a
variable displacement compressor 1, an evaporator 2, an expansion
valve 3, a condenser 4, and tubing 5 connecting them to each
other.
[0049] The variable displacement compressor 1 includes a housing
composed of a cylinder block 11, a front housing 12, a rear housing
13, and a valve plate 14. The cylinder block 11 is provided with a
plurality of cylinder bores 11a aligned in a circumferential
direction so as to be in parallel with one another. The plurality
of cylinder bores 11a pass through the cylinder block 11 in an
axial direction. Each of the cylinder bores 11a accommodates a
piston 15 such that the piston 15 can reciprocate. The head of each
of the pistons 15 defines a compression chamber in each of the
cylinder bores 11a.
[0050] One end side of the cylinder block 11 is connected to the
front housing 12. The cylinder block 11 and the front housing 12
are provided with axial holes passing through the cylinder block 11
and the front housing 12 and extending in the axial direction.
Inner portions of the axial holes constitute a crank chamber 16.
The axial hole of the front housing 12 is provided with a sealing
device S and a radial bearing 17. The axial hole of the cylinder
block 11 is provided with a radial bearing 18 and a thrust bearing
19. A drive shaft 20 is supported by the seal device S, the radial
bearing 17, the radial bearing 18, and the thrust bearing 19 so as
to be rotatable. An end of the drive shaft 20 is positioned in a
boss of the front housing 12. The drive shaft 20 is driven by an
engine EG for a vehicle through an electromagnetic clutch MG. The
engine EG serves as an exterior drive source. In a case where a
vehicle is not driven by the engine EG but is driven by a motor,
the motor serves as the exterior drive source.
[0051] In the crank chamber 16, a lag plate 21 is fixed to the
drive shaft 20, and a thrust bearing 22 is provided between the lag
plate 21 and the front housing 12. Further, on a rear side of the
lag plate 21, a swash plate SP, through which the drive shaft 20 is
inserted, is supported so as to be rotatable in synchronism with
the drive shaft 20 and to be capable of inclining relative to the
drive shaft 20. A bias spring 23 and a hinge mechanism 24 are
provided between the lag plate 21 and the swash plate SP. On an
outer peripheral side of the swash plate SP, there are provided
pairs of shoes 25 for both front and rear sides. Both shoes 25
being respectively sandwiched by the pistons 15.
[0052] The cylinder block 11 and the rear housing 13 are connected
to each other through the intermediation of the valve plate 14
provided therebetween. On a front surface of the valve plate 14,
there is provided an intake valve plate 26. On a rear surface of
the valve plate 14, there are provided a discharge valve plate 27
and a retainer 28. The intake valve plate 26, the valve plate 14,
the discharge valve plate 27, and the retainer 28 are fastened
together by a bolt 29 and a nut 30. Further, a bias spring 31 is
provided between the thrust bearing 19 and the intake valve plate
26.
[0053] The rear housing 13 is provided with an intake chamber 32
and a discharge chamber 33 formed therein. The valve plate 14 is
provided with an intake port passing therethrough for communicating
with the intake chamber 32. An intake reed portion of the intake
valve plate 26 is positioned on the compression chamber side of the
intake port. Further, the intake valve plate 26 and the valve plate
14 are provided with a discharge port passing therethrough for
communicating with the compression chamber. A discharge reed
portion of the discharge valve plate 27 is positioned on the
discharge chamber 33 side of the discharge port.
[0054] The rear housing 13 is provided with a control valve 34 as a
control device. The cylinder block 11, the intake valve plate 26,
and the valve plate 14 are provided with a bleed passage 35 passing
through those, for communicating the intake chamber 32 and the
crank chamber 16 with each other through a fixed restriction 35a.
Further, the cylinder block 11, the intake valve plate 26, the
valve plate 14, and the rear housing 13 are provided with a
pressure detecting passage 36a and air supply passages 36b and 36c
passing through those, for communicating the discharge chamber 33
and the crank chamber 16 with each other through the control valve
34. The pressure detecting passage 36a extends from the discharge
chamber 33 to the control valve 34. The air supply passage 36b
extends from the discharge chamber 33 to the control valve 34
through a fixed restriction 33a. The fixed restriction 33a serves
as a differential pressure generating mechanism. The pressure
detecting passage 36a and the air supply passage 36b also serve as
state pressure passages. The air supply passage 36c extends from
the control valve 34 to the crank chamber 16.
[0055] The control valve 34 includes, as shown in FIG. 2, a valve
housing composed of a first valve housing 37, an adjusting screw
38, and a second valve housing 39. The adjusting screw 38 is
threaded on an end of the first valve housing 37, thereby forming a
first pressure sensing chamber 40 serving as a state pressure
chamber. The first pressure sensing chamber 40 accommodates therein
a first bellows 41 serving as a first pressure sensing member. An
end of the first bellows 41 is fixed to the adjusting screw 38.
[0056] The adjusting screw 38 has a communication hole 38a passing
therethrough, for communicating the pressure detecting passage 36a
with a first control chamber 41a in the first bellows 41. Further,
the first valve housing 37 has a communication hole 37a passing
therethrough, for communicating the air supply passage 36b with the
first pressure sensing chamber 40. The communication holes 38a and
37a also serve as the state pressure passages.
[0057] The other end side of the first valve housing 37 is
connected to the second valve housing 39. The first valve housing
37 and the second valve housing 39 form a second pressure sensing
chamber 42 coaxial with the first pressure sensing chamber 40. The
first pressure sensing chamber 40 and the second pressure sensing
chamber 42 communicate with each other through an axial hole 37b.
Further, the first valve housing 37 has a communication hole 37c
passing therethrough, for communicating the air supply passage 36c
with the second pressure sensing chamber 42. Thus, the air supply
passage 36b can communicate with the air supply passage 36c through
the communication hole 37a, the first pressure sensing chamber 40,
the axial hole 37b, the second pressure sensing chamber 42, and the
communication hole 37c.
[0058] The second pressure sensing chamber 42 accommodates therein
a second bellows 43 serving as a second pressure sensing member.
The other end of the second bellows 43 is fixed to a fixed member
44 provided in the second pressure sensing chamber 42.
[0059] The other end of the first bellows 41 is fixed to a first
rod 45 extending into the axial hole 37b, while an end of the
second bellows 43 is fixed to a second rod 46 extending toward the
axial hole 37b and faces and abuts on the first rod 45. The axial
hole 37b, the first rod 45, and the second rod 46 constitute a
primary valve mechanism having a structure in which the periphery
of axial hole 37b serves as a valve seat, the second rod 46 serves
as a valve body, and a primary opening which is the degree of
opening of the axial hole 37b can be changed.
[0060] Further, the first valve housing 37 and the second valve
housing 39 are provided with an accommodation chamber 48 formed
therein. The accommodation chamber 48 connects to the first
pressure sensing chamber 40 through a first high pressure passage
49. The accommodation chamber 48 accommodates a constant pressure
valve 100. The constant pressure valve 100 includes a first
cylindrical body 50, a diaphragm 51, and a second cylindrical body
52 which are coaxial with one another.
[0061] The first cylindrical body 50 includes, as shown in FIG. 3,
a high pressure chamber 50a formed on one end side which is the
first high pressure passage 49 side, a constant pressure chamber
50b formed on the other end side, and a valve seat 50c having an
axial hole, which is held between the high pressure chamber 50a and
the constant pressure chamber 50b. Further, the first cylindrical
body 50 and the first valve housing 37 are provided with a second
high pressure passage 53 for communicating the constant pressure
chamber 50b with the second pressure sensing chamber 42. The high
pressure chamber 50a, the constant pressure chamber 50b, the first
high pressure passage 49, and the second high pressure passage 53
are high pressure passages.
[0062] The first cylindrical body 50 and the second cylindrical
body 52 sandwich the diaphragm 51 therebetween. A rod 54 extending
into the axial hole of the valve seat 50c is fixed to the diaphragm
51. An end of the rod 54 constitutes a valve body 54a positioned in
the high pressure chamber 50a and having a larger diameter.
Further, the second cylindrical body 52 accommodates therein a bias
spring 55 for biasing the diaphragm 51 toward the constant pressure
chamber 50b.
[0063] In the second pressure sensing chamber 42, the fixed member
44 is sandwiched between the first valve housing 37 and the second
valve housing 39. The fixed member 44 separates the second pressure
sensing chamber 42 into a first chamber 42a in which the second
bellows 43 is located and a second chamber 42b as the rest of the
fixed chamber 44.
[0064] Formed in the fixed member 44 are a third high pressure
passage 56 for communicating the second high pressure passage 53
with the second control chamber 43a in the second bellows 43, a
first release passage 57 extending in the axial direction, for
communicating the second control chamber 43a with the second
chamber 42b, and a second release passage 58 for communicating the
second chamber 42b with the first chamber 42a outside the second
bellows 43.
[0065] In the second chamber 42b of the second pressure sensing
chamber 42, there is provided an actuator 59 formed of a
piezoelectric element. As shown in FIG. 4, the actuator 59 is
connected to a controller 62 via a driver 61, with a lead wire 60
fixed to the second valve housing 39. The controller 62 is
connected to a plurality of sensors 63 and 64, such as a room
temperature sensor, an outside air temperature sensor, and a sensor
for the degree of opening of an accelerator of a vehicle, switches
65 and 66, and the like.
[0066] In the variable displacement compressor 1, as shown in FIG.
1, the intake chamber 32 is connected to the evaporator 2 through
the tubing 5, the evaporator 2 is connected to the expansion valve
3 through the tubing 5, the expansion valve 3 is connected to the
condenser 4 through the tubing 5, and the condenser 4 is connected
to the discharge chamber 33 of the variable displacement compressor
1. With this construction, the variable displacement compressor 1
is used together with an exterior refrigerant circulation circuit
composed of the evaporator 2, the expansion valve 3, the condenser
4, and the tubing 5 to constitute the vehicular refrigeration
circuit. In the vehicular refrigeration circuit, CO2 is adopted as
a refrigerant.
[0067] In the refrigeration circuit structured as described above,
the drive shaft 20 of the variable displacement compressor 1 is
rotated by the engine EG or the like. As a result, the swash plate
SP rotates while being inclined at a certain angle with respect to
the drive shaft 20, and each of the pistons 15 reciprocates in each
of the cylinder bores 11a, so a low-pressure refrigerant is
sequentially taken into the intake chamber 32 from the evaporator
2. The refrigerant is compressed in the compression chamber, and is
then discharged to the discharge chamber 33 to be discharged toward
the condenser 4. Air supplied to the evaporator 2 is provided for
the air conditioning inside the vehicle.
[0068] During the above-mentioned process, the control valve 34
controls the pressure in the crank chamber 16 and changes the
inclination angle of the swash plate SP to change the discharge
capacity as follows.
[0069] First, the pressure of the discharge chamber 33 is a
discharge pressure Pd which is high. However, the fixed restriction
33a exists between the discharge chamber 33 and the air supply
passage 36b, so, as shown in FIG. 2, pressure of the refrigerant in
the pressure detecting passage 36a is high discharge pressure PdH,
and pressure of the refrigerant in the air supply passage 36b is
low discharge pressure PdL. The high discharge pressure PdH is a
first state pressure and the low discharge pressure PdL is a second
state pressure.
[0070] The high discharge pressure PdH in the pressure detecting
passage 36a is introduced into the first control chamber 41a in the
first bellows 41 through the communication hole 38a. On the other
hand, the low discharge pressure PdL in the air supply passage 36b
is introduced into the first pressure sensing chamber 40 through
the communication hole 37a. Thus, the first bellows 41 moves while
causing a first load F1 due to a differential pressure .DELTA.Pd
between the high discharge pressure PdH and the low discharge
pressure PdL. Note that the high discharge pressure PdH and the low
discharge pressure PdL fluctuate according to the driving state,
the outside environment, or the like of the variable displacement
compressor 1, but the differential pressure .DELTA.Pd therebetween
has little fluctuation range.
[0071] Accordingly, the second rod 46 changes the primary opening
of the axial hole 37b. As a result, in the refrigeration circuit,
the pressure Pc of the crank chamber 16 is intended to be primarily
determined while taking into consideration the flow rate of the
refrigerant flowing through the exterior refrigerant circulation
circuit.
[0072] In this case, when the effective sectional area of the first
bellows 41 is A, the load of thrust resulting from flow rate
differential pressure is derived from the equation: A.DELTA.Pd.
When the effective sectional area of the first rod 45 and the
second rod 46 is B, the load caused by high-pressure correction is
derived from the equation: B(PdL-Pc). Thus, the first load F1 is
derived from the equation: A.DELTA.Pd+B(PdL-Pc).
[0073] As shown by the broken line of FIG. 5, the low discharge
pressure PdL fluctuates according to the driving state of the
variable displacement compressor 1, the outside environment, or the
like. Therefore, in the refrigeration circuit, the low discharge
pressure PdL is not introduced into the second control chamber 43a
as it is. As shown in FIG. 3, the low discharge pressure PdL in the
first pressure sensing chamber 40 is introduced into the high
pressure chamber 50a of the constant pressure valve 100 through the
first high pressure passage 49. The low discharge pressure PdL in
the high pressure chamber 50a is introduced into the constant
pressure chamber 50b through the axial hole of the valve seat 50c.
Note that the constant pressure in the high pressure chamber may
have a certain degree of error.
[0074] For example, when the low discharge pressure PdL in the
constant pressure chamber 50b is higher than a desired correction
pressure PdL0, the constant pressure chamber 50b presses the
diaphragm 51 against the bias force of the bias spring 55, so the
valve body 54a causes the degree of opening of the axial hole of
the valve seat 50c to decrease. On the other hand, when the low
discharge pressure PdL in the constant pressure chamber 50b is
lower than the desired correction pressure PdL0, the constant
pressure chamber 50b pulls the diaphragm 51 while yielding to the
bias force of the bias spring 55, so the valve body 54a causes the
degree of opening of the axial hole of the valve seat 50c to
increase. In this manner, as shown in FIG. 5, the pressure in the
constant pressure chamber 50b is maintained at the correction
pressure PdL0.
[0075] The correction pressure PdL0 in the constant pressure
chamber 50b is introduced into the second control chamber 43a of
the second bellows 43 through the second high pressure passage 53
and the third high pressure passage 56.
[0076] On the other hand, from the sensors 63 and 64, the switches
65 and 66, and the like, information on the driving state of the
variable displacement compressor 1, the outside environment, and
the like is transmitted to the controller 62. The controller 62
controls energization with respect to the actuator 59 through the
driver 61 according to a duty ratio shown in FIG. 6.
[0077] In this case, when the actuator 59 causes the secondary
opening of the first release passage 57 to increase due to the
energization control by the controller 62, the control pressure
PdLx in the second control chamber 43a in the second bellows 43
passes through the first release passage 57 and the second release
passage 58 to reach the first chamber 42a of the second pressure
sensing chamber 42, and passes through the communication passage
37c and the air supply passage 36c in the stated order to reach the
crank chamber 16. Therefore, the control pressure PdLx in the
second control chamber 43a becomes lower. Thus, the second load F2
of the second bellows 43 decreases, so the pressure Pc of the crank
chamber 16 is greatly affected by the movement of the first bellows
41 and the first rod 45.
[0078] In contrast, when the actuator 59 causes the secondary
opening of the first release passage 57 to decrease due to the
energization control by the controller 62, the control pressure
PdLx in the second control chamber 43a in the second bellows 43
becomes higher. Thus, the second load F2 of the second bellows 43
increases, so the pressure Pc of the crank chamber 16 becomes less
prone to be affected by the movement of the first bellows 41 and
the first rod 45.
[0079] Thus, as shown in FIG. 7, the second bellows 43 opposes the
first load F1 of the first bellows 41 with the control pressure
PdLx thereof to an appropriate degree to suitably correct the
second rod 46 such that the primary opening decreases or
increases.
[0080] In this case, when the effective sectional area of the
second bellows 43 is C, the second load F2 serving as a thrust is
derived by the equation: CPdLx. As a result, the following formula
is established.
[0081] (Formula 1) A.DELTA.Pd+B(PdL-Pc)=CPdLx
[0082] By using this formula, the pressure Pc of the crank chamber
16 is secondarily determined. In the variable displacement
compressor 1, the high pressure refrigerant in the discharge
chamber 33 is supplied to the crank chamber 16 such that the
resultant condition is satisfied, while an excess of the
refrigerant in the crank chamber 16 is delivered to the intake
chamber 32 through the bleed passage 35. As a result, the pressure
Pc of the crank chamber 16 is easily turned into an optimum state.
According to the pressure in the crank chamber 16, the inclination
angle of the swash plate SP changes, thereby appropriately changing
the discharge capacity.
[0083] During the above-mentioned processes, in the refrigeration
circuit, the constant pressure valve 100, which is different from
the actuator 59 whose energization is controlled from the outside,
maintains the high pressure in the high pressure chamber 50a to be
at the constant correction pressure PdL0. Therefore, it suffices
that the controller 62 controls energization with respect to the
actuator 59 on a condition that the constant correction pressure
PdL0 is maintained, thereby facilitating the control.
[0084] Consequently, according to the refrigeration circuit of
Embodiment 1, it is possible to relatively easy realization of
precise air conditioning according to the driving state of the
variable displacement compressor 1, the outside environment, and
the like. This enhances utility of the refrigeration circuit and
the variable displacement compressor 1.
[0085] Further, the refrigeration circuit adopts the first bellows
41 and the second bellows 43, so it is possible to operate the
second rod 46 with high precision. Further, the movement is limited
to the axial direction and the first load F1 and the second load F2
are also limited to the axial direction, so the first load F1 and
the second load F2 can oppose each other in a favorable manner.
[0086] Further, the refrigeration circuit adopts the actuator 59
formed of a piezoelectric element, so it is possible to achieve
both downsizing of the variable displacement compressor 1 and easy
control of energization.
Embodiment 2
[0087] A refrigeration circuit according to Embodiment 2 is
different from the refrigeration circuit according to Embodiment 1
in that it includes a fixed member 70 as shown in FIGS. 8 and 9.
The fixed member 70 includes a third high pressure passage 71 for
communicating the second high pressure passage 53 with the second
chamber 42b, a fourth high pressure passage 72 extending in the
axial direction, for communicating the second chamber 42b with the
second control chamber 43a, and a release passage 73 for
communicating the second control chamber 43a with the first chamber
42a outside the second bellows 43 formed in the fixed member 70.
The release passage 73 also serves as the fixed restriction. The
controller 62 controls energization with respect to the actuator 59
through the driver 61 according to the duty ratio shown in FIG. 10.
Other constructions are the same as those of Embodiment 1. The same
structures are denoted by the same reference numerals, and detailed
descriptions of those will be omitted.
[0088] In this case, the correction pressure PdL0 in the constant
pressure chamber 50b is introduced into the second chamber 42b of
the second pressure sensing chamber 42 through the second high
pressure passage 53 and the third high pressure passage 71. Thus,
when the actuator 59 causes the secondary opening of the fourth
high pressure passage 72 to increase due to the energization
control by the controller 62, the control pressure PdLx in the
second chamber 42b is introduced into the second control chamber
43a in the second bellows 43, and the control pressure PdLx in the
second control chamber 43a increases. Accordingly, the second load
F2 of the second bellows 43 increases, so the pressure Pc of the
crank chamber 16 is less prone to be affected by the movement of
the first bellows 41 and the first rod 45.
[0089] On the other hand, when the actuator 69 causes the secondary
opening of the fourth high pressure passage 72 to decrease due to
the energization control by the controller 62, the control pressure
PdLx in the second control chamber 43a becomes lower. Accordingly,
the second load F2 of the second bellows 43 decreases, so the
pressure Pc of the crank chamber 16 is greatly affected by the
movement of the first bellows 41 and the first rod 45.
[0090] Thus, also in the refrigeration circuit according to
Embodiment 2, the same operational effects as those of Embodiment 1
can be obtained.
[0091] Hereinbefore, Embodiments 1 and 2 of the present invention
are described. However, the present invention is not limited to
Embodiments 1 and 2. It is needless to say that the present
invention may be appropriately modified for application without
departing from the scope of the present invention.
[0092] For example, as shown in FIG. 11, the second bellows 43,
which is set such that an interior thereof is maintained at a
predetermined pressure, may be accommodated in the second pressure
sensing chamber 42, the control pressure PdLx may be introduced to
an exterior of the second bellows 43, and the actuator 59 may be
provided to a portion where the second pressure sensing chamber 42
is communicated with the crank chamber 16.
[0093] Further, as shown in FIG. 12, the second bellows 43, which
is set such that the interior thereof is maintained at a
predetermined pressure, may be accommodated in the second pressure
sensing chamber 42, the control pressure PdLx may be introduced to
the exterior of the second bellows 43 through the actuator 59, and
a fixed restriction 73 may be provided to a portion where the
second pressure sensing chamber 42 is communicated with the crank
chamber 16.
[0094] The present invention may be applied to a vehicular
refrigeration circuit, a vehicular variable displacement
compressor, and the like.
* * * * *