U.S. patent application number 09/837485 was filed with the patent office on 2001-11-01 for expansion valve for refrigerating cycle.
This patent application is currently assigned to CALSONIC KANSEI CORPORATION. Invention is credited to Fujiura, Katsunori, Ichimura, Nobuo, Kubota, Atsushi, Noda, Yoshitoshi.
Application Number | 20010035017 09/837485 |
Document ID | / |
Family ID | 18636231 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010035017 |
Kind Code |
A1 |
Kubota, Atsushi ; et
al. |
November 1, 2001 |
Expansion valve for refrigerating cycle
Abstract
A refrigerating cycle has a condenser, an evaporator, a variable
displacement compressor, and an expansion valve. The variable
displacement compressor is connected between the condenser and the
evaporator to form the refrigerating cycle, and includes a control
valve designed to provide a control valve characteristic sloping
downward with increase in a discharge pressure. The expansion valve
is connected between the condenser and the evaporator, to return a
refrigerant from the condenser through the evaporator to the
variable displacement compressor, and designed to provide an open
valve characteristic whose slope is approximately equal to the
downward slope of the control valve characteristic.
Inventors: |
Kubota, Atsushi; (Tochigi,
JP) ; Ichimura, Nobuo; (Gunma, JP) ; Noda,
Yoshitoshi; (Tochigi, JP) ; Fujiura, Katsunori;
(Tochigi, JP) |
Correspondence
Address: |
Richard L. Schwaab
FOLEY & LARDNER
Washington Harbour
3000 K Street, N.W., Suite 500
Washington
DC
20007-5109
US
|
Assignee: |
CALSONIC KANSEI CORPORATION
|
Family ID: |
18636231 |
Appl. No.: |
09/837485 |
Filed: |
April 19, 2001 |
Current U.S.
Class: |
62/217 ;
62/228.5 |
Current CPC
Class: |
F25B 49/022 20130101;
F25B 2600/21 20130101; F25B 41/335 20210101 |
Class at
Publication: |
62/217 ;
62/228.5 |
International
Class: |
F25B 041/04; F25B
001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 26, 2000 |
JP |
2000-126450 |
Claims
What is claimed is:
1. A refrigerating cycle comprising: a condenser; an evaporator; a
variable displacement compressor connected between the condenser
and the evaporator to form the refrigerating cycle, the variable
displacement compressor comprising a control valve designed to
provide a control valve characteristic sloping downward with
increase in a discharge pressure; and an expansion valve connected
between the condenser and the evaporator, to return a refrigerant
from the condenser through the evaporator to the variable
displacement compressor, and designed to provide an open valve
characteristic whose slope is approximately equal to the downward
slope of the control valve characteristic.
2. The refrigerating cycle as claimed in claim 1, in which the
control valve characteristic of the control valve is a relationship
between the discharge pressure on an outlet side of the variable
displacement compressor and a suction pressure on an inlet side of
the variable displacement compressor, while the open valve
characteristic of the expansion valve is a relationship between an
inlet pressure on an inlet side of the expansion valve and an
outlet pressure on an outlet side of the expansion valve, and in
which the variable displacement compressor is adapted to operate in
an operation area.
3. The refrigerating cycle as claimed in claim 2, in which the
expansion valve comprises a port defining a port area, and the
expansion valve further comprises a diaphragm defining a diameter,
and in which at least one of the port area and the diameter is so
sized that the open valve characteristic of the expansion valve is
higher than the control valve characteristic of the control valve
of the variable displacement compressor.
4. The refrigerating cycle as claimed in claim 3, in which the port
area of the port of the expansion valve is increased so as to allow
the expansion valve to provide the open valve characteristic whose
slope is approximately equal to the downward slope of the control
valve characteristic of the control valve.
5. The refrigerating cycle as claimed in claim 3, in which the
diameter of the diaphragm of the expansion valve is decreased so as
to allow the expansion valve to provide the open valve
characteristic whose slope is approximately equal to the downward
slope of the control valve characteristic of the control valve.
6. A refrigerating cycle comprising: a condenser; an evaporator; a
variable displacement compressor connected between the condenser
and the evaporator to form the refrigerating cycle, the variable
displacement compressor comprising a control valve designed to
provide a control valve characteristic sloping downward with
increase in a discharge pressure, the variable displacement
compressor being adapted to operate in an operation area defined
between a first non-operation area and a second non-operation area
opposite to the first non-operation area, the second non-operation
area defining the discharge pressure higher than the discharge
pressure that is defined in the operation area; and an expansion
valve connected between the condenser and the evaporator, to return
a refrigerant from the condenser through the evaporator to the
variable displacement compressor, and designed to provide an open
valve characteristic which intersects, at an intersection point
defined in one of the first non-operation area and the second
non-operation area of the variable displacement compressor, with
the control valve characteristic of the control valve.
7. The refrigerating cycle as claimed in claim 6, in which the
control valve characteristic of the control valve is a relationship
between the discharge pressure on an outlet side of the variable
displacement compressor and a suction pressure on an inlet side of
the variable displacement compressor, while the open valve
characteristic of the expansion valve is a relationship between an
inlet pressure on an inlet side of the expansion valve and an
outlet pressure on an outlet side of the expansion valve.
8. The refrigerating cycle as claimed in claim 7, in which the
expansion valve comprises a port defining a port area, the port
area being restricted constantly so as to allow the expansion valve
to provide the open valve characteristic whose slope is less
inclined than the downward slope of the control valve
characteristic of the control valve.
9. The refrigerating cycle as claimed in claim 8, in which the open
valve characteristic of the expansion valve and the control valve
characteristic of the control valve intersect with each other at
the intersection point defined in the first non-operation area.
10. The refrigerating cycle as claimed in claim 7, in which the
expansion valve comprises a port defining a port area, the port
area being increased so as to allow the expansion valve to provide
the open valve characteristic whose slope is more inclined than the
downward slope of the control valve characteristic of the control
valve.
11. The refrigerating cycle as claimed in claim 10, in which the
open valve characteristic of the expansion valve and the control
valve characteristic of the control valve intersect with each other
at the intersection point defined in the second non-operation area.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to an expansion valve for a
refrigerating cycle which is suitable for an air conditioning
system for a motor vehicle.
[0002] Generally, the air conditioning system for the motor vehicle
is constituted of the refrigerating cycle in which a refrigerant
discharged from a compressor is returned to the compressor by way
of a condenser, the expansion valve and an evaporator.
[0003] The expansion valve is so designed as to control super heat
by evaporation temperature at an outlet of the evaporator and a
pressure (low pressure) at the outlet of the evaporator. Thereby,
the expansion valve is so made as to be free from being influenced
by any high pressure which may cause a disturbance.
[0004] As is seen in FIG. 7, the expansion valve shows an open
valve characteristic TXV which features substantially a horizontal
graph. In other words, the open valve characteristic TXV is not
dependent on the high pressure.
[0005] The open valve characteristic TXV of the expansion valve in
FIG. 7 is obtained at an evaporator outlet temperature Te of
0.degree. C. In FIG. 7, the ordinate is an evaporator outlet
pressure Pe (more specifically, Pe.sub.out), while the abscissa is
a discharge pressure Pd. There is defined an expansion valve closed
zone on substantially an upper side of the open valve
characteristic TXV. Contrary to this, there is defined an expansion
valve open zone on substantially a lower side of the open valve
characteristic TXV. Moreover, as is seen in FIG. 7, on
substantially a left side and substantially a right side of an
operation area B, there are defined, respectively, a first
non-operation area A-1 and a second non-operation area A-2, in each
of which the compressor does not operate.
[0006] Furthermore, FIG. 7 shows a control valve characteristic C/V
featuring a downward slope in accordance with the discharge
pressure Pd which gets higher gradually. The control valve
characteristic C/V is the one that is obtained when a variable
displacement compressor equipped with a control valve is combined
with the expansion valve that is set at the open valve
characteristic TXV featuring the substantially horizontal graph. In
the expansion valve closed zone, there is caused an interfered
control area "d" as is depicted by diagonal lines in FIG. 7.
[0007] Failures such as hunting and the like may occur, for
example, under the following three conditions combined: 1. The
expansion valve is set at 5 kg/cm2G (namely, in the interfered
control area "d"). 2. Being in the expansion valve closed zone. 3.
The compressor is likely to pull the refrigerant forcibly.
[0008] In order to prevent such failures from occurring, there is
provided one possible solution, that is, to make the control valve
characteristic C/V non-linear so that the interfered control area
"d" does not occur up to an intersection point P. However, such
solution complicates the constitution of the control valve
characteristic C/V.
[0009] For preventing, with ease, the interfered control area "d"
from occurring, the open valve characteristic TXV of the expansion
valve is set higher than the control valve characteristic C/V, as
is depicted by a dashed line in FIG. 7. In this case, however, the
valve opening of the expansion valve gets large when the discharge
pressure is high (high load applied) since the control valve
characteristic C/V is included in the expansion valve open
zone.
[0010] When the valve opening of the expansion valve gets large,
the refrigerant flowrate will increase. Thereby, it becomes
impossible to take the proper super heat, and the refrigerating
power is deteriorated. Simultaneously with this, consumption
(power) of the variable displacement compressor is increased, thus
ending up an increase in cost (not preferable).
SUMMARY OF THE INVENTION
[0011] It is, therefore, an object of the present invention to
provide an expansion valve for a refrigerating cycle for solving
the above mentioned problems.
[0012] According to a first aspect of the present invention, there
is provided a refrigerating cycle comprising a condenser, an
evaporator, a variable displacement compressor, and an expansion
valve. The variable displacement compressor is connected between
the condenser and the evaporator to form the refrigerating cycle,
and comprises a control valve designed to provide a control valve
characteristic sloping downward with increase in a discharge
pressure. The expansion valve is connected between the condenser
and the evaporator, to return a refrigerant from the condenser
through the evaporator to the variable displacement compressor, and
designed to provide an open valve characteristic whose slope is
approximately equal to the downward slope of the control valve
characteristic.
[0013] According to one of a second aspect and a third aspect of
the present invention, there is provided a refrigerating cycle
comprising a condenser, an evaporator, a variable displacement
compressor, and an expansion valve. The variable displacement
compressor is connected between the condenser and the evaporator to
form the refrigerating cycle, and comprises a control valve
designed to provide a control valve characteristic sloping downward
with increase in a discharge pressure. Furthermore, the variable
displacement compressor is adapted to operate in an operation area
defined between a first non-operation area and a second
non-operation area opposite to the first non-operation area, the
second non-operation area defining the discharge pressure higher
than the discharge pressure that is defined in the operation area.
The expansion valve is connected between the condenser and the
evaporator, to return a refrigerant from the condenser through the
evaporator to the variable displacement compressor, and designed to
provide an open valve characteristic which intersects, at an
intersection point defined in one of the first non-operation area
and the second non-operation area of the variable displacement
compressor, with the control valve characteristic of the control
valve.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a graph showing an open valve characteristic TXV
of an expansion valve 5, and a control valve characteristic C/V of
a variable displacement compressor 1, according to a first
preferred embodiment of the present invention;
[0015] FIG. 2 is a block diagram of a refrigerating cycle;
[0016] FIG. 3 is a schematic diagram of the expansion valve 5;
[0017] FIG. 4 is a graph showing an intersection point pressure Pa
relative to a pressure control line;
[0018] FIG. 5 is a graph showing an intersection point P (the open
valve characteristic TXV intersecting with the control valve
characteristic C/V) disposed in a first non-operation area A-1,
according to a second preferred embodiment of the present
invention;
[0019] FIG. 6 is a graph showing the intersection point P disposed
in a second non-operation area A-2, according to a third preferred
embodiment of the present invention; and
[0020] FIG. 7 (similar to FIG. 1) is a graph showing an open valve
characteristic TXV of an expansion valve and a control valve
characteristic C/V of a variable displacement compressor, according
to a related art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] As is seen in FIG. 1 through FIG. 4, there is provided an
expansion valve 5 for a refrigerating cycle and data related
thereto, according to a first preferred embodiment of the present
invention.
[0022] As is seen in FIG. 2, there is provided the refrigerating
cycle of an air conditioning system for a motor vehicle. A
refrigerant is discharged from a variable displacement compressor
1, and is then returned to the variable displacement compressor 1
by way of a condenser 3, the expansion valve 5 and an evaporator
7.
[0023] A control valve 9 is built in the variable displacement
compressor 1. When being combined with the expansion valve 5 (to be
mentioned afterwards), the variable displacement compressor 1
(control valve 9) shows a control valve characteristic C/V as is
seen in FIG. 1.
[0024] In FIG. 1, the ordinate is a suction pressure Ps (or an
evaporator outlet pressure Pe.sub.out), while the abscissa is a
discharge pressure Pd (or an expansion valve inlet pressure Pex).
The variable displacement compressor 1 operates in an operation
area B. There is defined a first intersection zone A-1
substantially on a left side of the operation area B in FIG. 1. In
the first intersection zone A-1, the suction pressure Ps (low
pressure) is equal to the discharge pressure Pd (high pressure), to
thereby make the variable displacement compressor 1 stay at rest
(not operating). There is provided a second intersection zone A-2
substantially on a right side of the operation area B in FIG. 1. In
the second intersection zone A-2, the discharge pressure Pd is so
high as to disengage a clutch, to thereby make the variable
displacement compressor 1 stay at rest (not operating). This
summarizes that the first intersection zone A-1 disposed
substantially on the left side of the operation area B in FIG. 1 is
defined as a first non-operation area A-1, while the second
intersection zone A-2 disposed substantially on the right side of
the operation area B in FIG. 1 is defined as a second non-operation
area A-2.
[0025] As is seen in FIG. 3, the expansion valve 5 has a port 11,
and a ball valve 13 for controlling a port area A of the port 11. A
spring pressure is applied upwardly to the ball valve 13 from an
energizing spring 15, while a diaphragm pressure is applied
downwardly to the ball valve 13 from a diaphragm 19 by way of a
shaft 17. The spring pressure of the energizing spring 15 is
arbitrarily adjustable by using an adjusting measure 21 such as
screw and the like. The diaphragm pressure is variable according to
pressure and temperature of a refrigerant at an outlet of the
evaporator 7. Then, a differential pressure between the spring
pressure and the diaphragm pressure contributes toward obtaining a
variable set value of the expansion valve 5.
[0026] As is seen in FIG. 1, the expansion valve 5 combined with
the variable displacement compressor 1 shows an open valve
characteristic TXV that has substantially the same slope as that of
the control valve characteristic C/V.
[0027] The open valve characteristic TXV of the expansion valve 5
in FIG. 1 is a control characteristic when an evaporator outlet
temperature Te of the refrigerant at an outlet of the evaporator 7
is 0.degree. C.
[0028] Namely, the open valve characteristic TXV having
substantially the same slope as that of the control valve
characteristic C/V as is seen in FIG. 1 can be obtained by
increasing the port 11 in diameter or by decreasing the diaphragm
19 in diameter.
[0029] More specifically, the following expressions are obtained
using an effective diameter D of the diaphragm 19, a diaphragm
pressure PD, a shaft area S, the port area A, a spring constant K
(of the energizing spring 15), a lift X (an extent that the ball
valve 13 is lifted), a load FD applied to the diaphragm 19, and a
load FX applied to the ball valve 13:
[0030] [Math 1]
FX={A.multidot.Pex-(A-S).multidot.Pe.sub.in}+K.multidot.X
FD=D.multidot.(PD-Pe.sub.out)-S.multidot.(Pe.sub.inPe.sub.out)
(1)
[0031] where Pe.sub.in is an evaporator inlet pressure, and
Pe.sub.out is an evaporator outlet pressure.
[0032] In the expression (1) above, FX=FD (equilibrium). Thereby,
the following expression (2) is obtained:
[0033] [Math 2]
{A.multidot.Pex-(A-S)Pe.sub.in}+K.multidot.X=D.multidot.(PD-Pe.sub.out)-S.-
multidot.(Pe.sub.in-Pe.sub.out) (2)
[0034] When Pc.sub.in=Pe.sub.out, the following expression (3) is
obtained:
[0035] [Math 3]
{A.multidot.Pex-(A-S-D).multidot.Pe.sub.in}+K.multidot.X=D.multidot.PD(A-S-
-D).multidot.Pe.sub.in=A.multidot.Pex-D-PD+K.multidot.X (3)
[0036] Thus, the following expression (4) is obtained:
[0037] [Math 4]
Pe=A/(A-S-D).multidot.Pex-D/(A-S-D).multidot.PD+K.multidot.X/(A-S-D)
(4)
[0038] where A/(A-S-D) is a valve opening (high pressure
dependent), (A-S-D).multidot.PD is a slope of the set value
corresponding to temperature, and (A-S-D) is a set value of the
spring adjustment by the energizing spring 15.
[0039] With the expressions above, it is evident that increasing
the port area A of the port 11 or decreasing the effective diameter
D of the diaphragm 19 contributes toward allowing, with ease, the
open valve characteristic TXV to have substantially the same slope
as that of the control valve characteristic C/V.
[0040] In this case, a relation of the open valve characteristic
TXV of the expansion valve 5 relative to the control valve
characteristic C/V of the control valve 9 is described below. As is
seen in FIG. 4, the ordinate is a low pressure, while the abscissa
is a temperature of the refrigerant (at the outlet of the
evaporator 7). In order to take a proper super heat, an
intersection point pressure Pa (where a refrigerant saturation line
WL intersects with the open valve characteristic TXV of the
expansion valve 5) is defined, in the following manner, with
respect to a control line (the suction pressure Ps) of the variable
displacement compressor 1:
[0041] The intersection point pressure Pa is set at a pressure not
greater than the suction pressure Ps during an operation mode when
the refrigerating power is prioritized (see continuous line in FIG.
4). Contrary to this, the intersection point pressure Pa is set at
a pressure not less than the suction pressure Ps during a saving
mode (see dashed line in FIG. 4).
[0042] With the expansion valve 5 for the refrigerating cycle thus
constituted, the control valve characteristic C/ V does not
intersect with the open valve characteristic TXV, to thereby
prevent an interfered control area "d" from occurring which is
responsible for failures such as hunting and the like.
[0043] In addition, when a high load is applied, the set value of
the expansion valve 5 is lowered, to thereby cause a preferable
valve opening (likely to be restricted). The thus obtained
preferable valve opening contributes toward causing the proper
super heat, to thereby improve the refrigerating power.
Simultaneously with this, the refrigerant flowrate is reduced, to
thereby improve a saving mode of the variable displacement
compressor 1.
[0044] On the other hand, when a low load is applied, the valve
opening is likely to be open. The thus obtained valve opening
contributes toward causing a proper super heat, and a proper
refrigerant flowrate is obtained throughout the entire area of the
evaporator 7. Thereby, the evaporator 7 is improved in terms of
temperature characteristic (no deviation in temperature
distribution), and an effective refrigeration is achieved.
[0045] As is seen in FIG. 5, there is provided a graph showing the
open valve characteristic TXV of the expansion valve 5, and the
control valve characteristic C/V of the control valve 9 built in
the variable displacement compressor 1, according to a second
preferred embodiment of the present invention.
[0046] The open valve characteristic TXV of the expansion valve 5
features substantially a horizontal graph, by restricting
constantly the port area A of the port 11. Thereby, the open valve
characteristic TXV is small in terms of dependency on high
pressure. Contrary to this, the control valve characteristic C/V
features a downward slope toward higher pressure, in other words,
the downward slope in accordance with the discharge pressure Pd
which gets higher gradually. In the second preferred embodiment,
the intersection point P is set in the first intersection zone A1
(or the first non-operation area A-1) that is out of the operation
area B, to thereby prevent failures from occurring such as hunting
and the like.
[0047] Moreover, as is seen in FIG. 6, there is provided a graph
showing the open valve characteristic TXV of the expansion valve 5,
and the control valve characteristic C/V of the control valve 9
built in the variable displacement compressor 1, according to a
third preferred embodiment of the present invention.
[0048] The open valve characteristic TXV features a downward slope
toward higher pressure, by increasing the port area A of the port
11. On the other hand, the control valve characteristic C/V also
features a downward slope toward high pressure, in other words, the
downward slope in accordance with the discharge pressure Pd which
gets higher gradually. In addition, the open valve characteristic
TXV is not parallel relative to the control valve characteristic
C/V. In the third preferred embodiment, the intersection point P is
set in the second intersection zone A-2 (or the second
non-operation area A-2) that is out of the operation area B, to
thereby prevent failures from occurring such as hunting and the
like.
* * * * *