US20090311111A1

US20090311111A1 - Ejector

Info

Publication number: US20090311111A1
Application number: US12/456,334
Authority: US
Inventors: Keiichi Yoshii
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2008-06-16
Filing date: 2009-06-15
Publication date: 2009-12-17
Also published as: DE102009024712A1; CN101608642A; JP2009299609A

Abstract

An ejector includes a nozzle, a body portion and a pressurizing portion. The body portion has a fluid suction port from which a fluid is drawn by a jet flow of a fluid jetted from the nozzle, and a fluid suction passage through which the fluid drawn from the fluid suction port flows while a flow direction of the drawn fluid is changed. The fluid suction passage has a suction inlet part, a suction space part, and a suction outlet part from which the fluid from the suction space part flows out in a jet direction of the jet fluid. A fluid passage area of the suction inlet part is smaller than an open area of the fluid suction port and a fluid passage area of the suction space part, and the fluid passage area of the suction outlet part is smaller than that of the suction space part.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2008-156331 filed on Jun. 16, 2008, the contents of which are incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to an ejector in which a fluid is drawn from a fluid suction port by using suction action of a high-speed jet fluid jetted from a nozzle.

BACKGROUND OF THE INVENTION

JP 2004-270460A (corresponding to US 2004/0172966 A1) proposes an ejector that includes a nozzle for jetting a fluid at a high speed, a fluid suction port from which a fluid is drawn by using suction action of the high-speed jet fluid jetted from a fluid jet port of the nozzle, and a pressure increasing portion (e.g., diffuser) in which the jet fluid and the drawn fluid are mixed and the pressure of the mixed fluid is increased. Furthermore, the ejector is provided with a taper-shaped needle that extends from an interior of a fluid passage of the nozzle to an exterior of the fluid jet port of the nozzle concentrically with the fluid passage of the nozzle. The tip portion of the needle is tapered toward downstream in a jet direction of the fluid in the nozzle.
In the above-described ejector, the fluid is jetted from the fluid jet port of the nozzle to flow along the surface of the needle so that the jet fluid has a suitable expanding shape, thereby improving the nozzle efficiency of the ejector. The nozzle efficiency is an energy conversion efficiency in the nozzle, and is defined as a ratio of a speed energy of the jet fluid to an enthalpy difference (expansion energy) between the fluid at the inlet of the nozzle and the fluid at the jet port of the nozzle.
However, according to the studies by the inventor of the present applicant, it is difficult to increase a pressurizing amount of the fluid in the diffuser by an amount corresponding to an increased amount of the nozzle efficiency even when the nozzle efficiency is increased.
In order to sufficiently increase the pressurizing amount of the fluid in the diffuser, it is necessary not only to increase the nozzle efficiency but also to reduce a mixing energy loss that is caused while the jet fluid and the drawn fluid are mixed.
The mixing energy loss is easily caused when the flow direction (suction direction) of the fluid drawn into the ejector is different from the jet direction of the fluid as in the above ejector. If the suction direction and the jet direction are different from each other in the ejector, the flow direction of the suction fluid needs to be changed to the jet direction of the jet fluid while the suction fluid and the jet fluid are mixed, thereby causing a velocity distribution in the suction fluid.
When the suction fluid having the velocity distribution is mixed with the jet fluid, the mixed fluid of the jet fluid and the suction fluid becomes in an un-uniform state, and thereby the pressurizing amount in the diffuser is reduced.

SUMMARY OF THE INVENTION

In view of the foregoing problems, it is an object of the present invention to provide an ejector, which can reduce energy loss caused while jet fluid and suction fluid are mixed, thereby increasing a pressurizing amount in a pressurizing portion of the ejector.
According to as aspect of the present invention, an ejector includes a nozzle configured to decompress and jet a fluid, a body portion and a pressurizing portion. The body portion has a fluid suction port from which a fluid is drawn by a jet flow of the fluid jetted from the nozzle, and a fluid suction passage through which the fluid drawn from the fluid suction port flows while a flow direction of the fluid drawn from the fluid suction port is changed. In the pressurizing portion, a pressure of a fluid mixture between the fluid flowing through the fluid suction passage from the fluid suction port and the fluid jetted from the nozzle is increased. In the ejector, the fluid suction passage is configured to have a suction inlet part into which the fluid from the fluid suction port flows, a suction space part in which the flow direction of the fluid flowing from the fluid suction port is changed, and a suction outlet part from which the fluid from the suction space part flows out in a jet direction of the jet fluid. Furthermore, the suction inlet part has a fluid passage area that is smaller than an open area of the fluid suction port and a fluid passage area of the suction space part, and the fluid passage area of the suction outlet part is smaller than the fluid passage area of the suction space part.
Because the fluid passage area of the suction inlet part is smaller than the open area of the fluid suction port, the flow speed of the suction fluid flowing from the suction inlet part into the suction space part can be increased than the flow speed of the suction fluid drawn from the fluid suction port. Thus, it is possible to increase the dynamical pressure of the suction fluid flowing from the suction inlet part to the suction space part. Therefore, the fluid is disturbed in the suction space part, thereby effectively mixing the fluid in the suction space part of the ejector. Furthermore, because the flow speed of the suction fluid after flowing into the suction space part is decreased more than the flow speed of the fluid just flowing into the suction space part, the dynamical pressure of the suction fluid is converted to the static pressure thereof in the suction space part. Accordingly, the suction space part can be used for equalizing the pressure of the fluid flowing out of the suction outlet part. In addition, because the fluid passage area of the suction outlet part is smaller than the fluid passage area of the suction space part in the ejector, it can prevent the fluid from flowing out of the suction outlet part before a different in the flow speed distribution is reduced. As a result, the ejector can reduce energy loss caused while the jet fluid and the suction fluid are mixed, thereby increasing a pressurizing amount in the pressurizing portion.
The fluid suction port may be connected to a fluid suction pipe in which the fluid to be drawn into the fluid suction port flows. In this case, the fluid passage area of the suction inlet part is smaller than a fluid passage area of the fluid suction pipe. Furthermore, the fluid passage area of the fluid suction pipe can be gradually reduced as toward the fluid suction port.
For example, the suction inlet part may be an orifice. Alternatively/further, an extending line of a flow direction of the fluid drawn from the fluid suction port may be crossed perpendicularly with an extending line of the jet direction of the fluid jetted from the nozzle. The suction space part may be provided on an outer peripheral side of the nozzle.
In the ejector, a ratio of the fluid passage area of the suction inlet part to the open area of the fluid suction port may be equal to or smaller than 0.5, or/and a ratio of the fluid passage area of the suction inlet part to the maximum fluid passage area of the fluid suction pipe may be equal to or smaller than 0.5, or/and a ratio of the fluid passage area of the suction outlet part to the fluid passage area of the suction space part may be equal to or smaller than 0.5.
As an example, the suction space part may be an approximately cylindrical passage provided on the outer peripheral side of the nozzle to extend in an axial direction of the nozzle, and the suction outlet part may extend coaxially with the cylindrical passage of the suction space part and is tapered downstream. Furthermore, the nozzle may be located to protrude into the suction outlet part from the suction space part coaxially with the cylindrical passage, and the suction inlet part may be open to the cylindrical passage in a direction approximately perpendicular to the axial direction of the nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional objects and advantages of the present invention will be more readily apparent from the following detailed description of preferred embodiments when taken together with the accompanying drawings. In which:

FIG. 1 is a schematic diagram showing a refrigerant cycle device having an ejector, used for a heat pump water heater, according to a first embodiment of the invention;

FIG. 2 is a schematic sectional view showing the ejector according to the first embodiment; and

FIG. 3 is a schematic sectional view showing an ejector according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

An ejector 15 and a refrigerant cycle device 10 including the ejector 15 according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. In the present embodiment, the refrigerant cycle device 10 having the ejector 15 is typically used for a heat pump water heater 1 shown in FIG. 1.
The heat pump water heater 1 includes a water circulation circuit 20 in which water in a water tank 21 is circulated, and the refrigerant cycle device 10 which is configured to heat water to be stored in the water tank 21. The water tank 21 is used for temporally storing the hot water heated by the refrigerant cycle device 10. In the present embodiment, a refrigerant as an example of a fluid circulates in the refrigerant cycle device 10, and carbon dioxide (CO2) is used as the refrigerant. When the carbon dioxide is used as the refrigerant in the refrigerant cycle device 10, the pressure of high-pressure side refrigerant discharged from a compressor 11 becomes higher than the critical pressure of the refrigerant.
First, the water circulation circuit 20 will be described. The water tank 21 is a hot water storage tank made of a metal (e.g., stainless steel) having a heat insulating structure, in which high-temperature hot water can be stored for a long time. Generally, the water tank 21 is made of a metal having a sufficient corrosion-resistance property.
How water stored in the water tank 21 is supplied to an exterior from a hot water outlet provided at an upper portion of the water tank 21. The hot water from the hot water outlet of the water tank 21 can be suitably mixed with tap water by using a temperature adjustment valve, and then is supplied to a using place such as a kitchen, a bathroom or the like. A water inlet is provided at a lower portion of the water tank 21 so that water such as tap water can be supplied to the water tank 21 from the water inlet of the water tank 21.
An electrical pump 22 for circulating water is located in the water circulation circuit 20. The operation of the electrical pump 22 is controlled by control signal output from an electrical control portion (not shown). When the electrical control portion causes the electrical pump 22 to be operated, water circulates from the electrical pump 22, to a water passage 12 a of a water-refrigerant heat exchanger 12, the water storage tank 21, and the electrical pump 22, in this order.
Next, the refrigerant cycle device 10 will be described. The refrigerant cycle device 10 includes the compressor 11 configured to draw and compress the refrigerant and to discharge the compressed refrigerant. For example, the compressor 11 is an electrical compressor that includes a compression mechanism 11 a having a fixed discharge capacity, and an electrical motor 11 b for driving the compression mechanism 11 a. As the compression mechanism 11 a, various-type compression mechanisms such as a scroll type, a vane type, a rolling-piston type may be used.
Because the operation of the electrical motor 11 b, such as the rotational speed of the electrical motor 11 b, is controlled by using the control signal output from the electrical control portion, an alternate current motor or a direct current motor may be used. By controlling the rotational speed of the electrical motor 11 b, the refrigerant discharge capacity (displacement) of the compression mechanism 11 a can be changed. Thus, the electrical motor 11 b can be used as a discharge capacity varying portion for varying the refrigerant discharge capacity of the compression mechanism 11 a.
A refrigerant passage 12 b of the water-refrigerant heat exchanger 12 is connected to the refrigerant discharge side of the compressor 11. The water-refrigerant heat exchanger 12 is a heat exchanger having therein the refrigerant passage 12 b through which high-temperature and high-pressure refrigerant discharged from the compressor 11 flows, and the water passage 12 a through which water flows to perform heat exchange with the refrigerant flowing through the refrigerant passage 12 b. Thus, heat of the high-temperature and high-pressure refrigerant discharged from the compressor 11 is radiated to the water in the water-refrigerant heat exchanger 12, so that the water is heated and the refrigerant is cooled in the water-refrigerant heat exchanger 12. In the present embodiment, the water-refrigerant heat exchanger 12 is a refrigerant radiator for cooling the refrigerant discharged from the compressor 11.
In the present embodiment, because the refrigerant cycle device 10 is operated with a super-critical refrigerant state, the refrigerant (e.g., carbon dioxide) is not condensed while passing through the refrigerant passage 12 b of the water-refrigerant heat exchanger 12.
A branch portion 13 is connected to an outlet side of the refrigerant passage 12 b of the water-refrigerant heat exchanger 12 such that high-pressure refrigerant flowing from the refrigerant passage 12 b is branched by the branch portion 12 into first and second streams. The branch portion 13 is a three-way joint having a single refrigerant inlet and two refrigerant outlets. The three-way joint may have different pipe diameters or may have the same pipe diameter. The branch portion 13 may be formed from a metal black or a resin block having therein plural refrigerant passages.
One end of a first refrigerant pipe 14 a is connected to one refrigerant outlet of the branch portion 13, and the other end of the first refrigerant pipe 14 a is connected to a refrigerant inlet side of a nozzle 151 of the ejector 15, so that the refrigerant of the first stream branched at the branch portion 13 flows into the refrigerant inlet side of the nozzle 151 of the ejector 15 through the first refrigerant pipe 14 a. One end of a second refrigerant pipe 14 b is connected to the other refrigerant outlet of the branch portion 13, and the other end of the second refrigerant pipe 14 b is connected to a refrigerant inlet side of an electrical expansion valve 17, so that the refrigerant of the second stream branched at the branch portion 13 flows into the refrigerant inlet side of the electrical expansion valve 17 through the second refrigerant pipe 14 b.
The ejector 15 is used as a refrigerant decompression portion for decompressing the refrigerant at the nozzle 151, and as a kinetic energy pumping portion for circulating the refrigerant by using the suction action of the jet refrigerant jetted from the nozzle 151. Next, the detail structure of the ejector 15 will be described with reference to FIG. 2.
As shown in FIG. 2, the ejector 15 includes the nozzle 151, a body portion 152, a diffuser 153, a needle 154, a driving portion 155 or the like. The nozzle 151 is configured so as to decompress the refrigerant flowing into the interior of the nozzle 151 through the first refrigerant pipe 14 a in iso-entropy. The nozzle 151 can be formed from a metal member having an approximately cylindrical shape by drilling or cutting or the like. For example, the nozzle 151 may be made of a stainless steel, for example.
For example, the nozzle 151 is formed by coaxially combining two cylindrical members having different diameters. That is, the nozzle 151 includes a large-diameter portion 151 a, and a small-diameter portion 151 b. The outer peripheral surface of the large-diameter portion 151 a is press-fitted into the body portion 152. The large-diameter portion 151 a is provided with a nozzle inlet port 151 d through which the refrigerant flowing from the first refrigerant pipe 14 a flows into a refrigerant passage 151 c provided in the nozzle 151.
The refrigerant passage 151 c is provided in the nozzle 151 such that the refrigerant flows through the refrigerant passage 151 c from a side of the large-diameter portion 151 a to a side of the small-diameter portion 151 b. Furthermore, the refrigerant passage 151 c extends in the axial direction of the nozzle 151 such that the refrigerant passage area of the refrigerant passage 151 c of the nozzle 151 is gradually reduced in a downstream portion (i.e., the side of the small-diameter portion 151 b) of the refrigerant passage 151 c. Thus, the refrigerant passing through the refrigerant passage 151 c is decompressed in the small-diameter portion, and the decompressed refrigerant is jetted as shown by the arrow 100 from a refrigerant jet port 151 e that is provided at the most downstream position of the refrigerant passage 151 c.
The needle 154 is located in the refrigerant passage 151 c of the nozzle 151 such that the refrigerant passage area of the refrigerant passage 151 c is changed in accordance with a displacement of the needle 154 in the axial direction of the nozzle 151. The needle 154 is a needle-like member that extends coaxially with the nozzle 151. The needle 154 can be formed by cutting a cylindrical metal member such as a stainless steel member.
The needle 154 has a tip end portion tapered downstream in a refrigerant jet direction, on a side of the refrigerant jet port 151 e of the nozzle 151. The tip end portion of the needle 154 extends from the refrigerant jet port 151 e of the nozzle 151 by a dimension to a downstream side. Thus, when the needle 154 is displaced, the refrigerant passage area of the refrigerant passage 151 c and the open area of the refrigerant jet port 151 e are changed. The other end portion of the needle 154 opposite to the tapered tip end portion is provided with a screw portion (e.g., male screw portion) to which the driving portion 155 is connected.
The driving portion 155 is, for example, a motor actuator for driving and displacing the needle 154, and is configured to have a coil 155 a, a rotor 155 b and a can 155 c. The coil 155 a is configured to generate a rotation magnetic force in accordance with a control signal output from the electrical control portion, so that the rotor 155 b can be rotated around the axial of the nozzle 151.
A screw 158 is fitted into the nozzle 151, and the needle 154 is slidably inserted into an inner diameter portion of the screw 158. One end portion of the needle 154 on a side of the driving portion 155 is connected to the rotor 155 b via a washer 156. The rotor 155 b has a cylinder that is provided with a female screw portion on its inner side, and the female screw portion of the rotor 155 b is screwed with a male screw provided on an outer peripheral surface of the screw 158. Thus, when the rotor 155 b rotates, the rotator 155 b and the needle 154 displace in the axial direction of the needle 154. The can 155 c is a metal cup-like can 155 c made of a non-magnetic metal, and is a housing member for housing the rotor 155 b. The can 155 c is welded and fixed to one end side of the body portion 152 in the axial direction. A spring 157 is disposed between the washer 156 and the screw 158, and is biased to push the rotor 155 b in an axial direction opposite to the nozzle side.
The nozzle 151 and the driving portion 155 are fixed to the body portion 152. The body portion 152 has therein various open holes through which the refrigerant flows into or flows out of the interior of the body portion 152, and various refrigerant passages respectively communicating with the various open holes. The body portion 152 can be formed from a cylindrical metal member by cutting and drilling.
An outlet of the diffuser 153 is coupled to a refrigerant inlet side of a first evaporator 15 as described later. The various open holes provided in the body portion 152 are a refrigerant inlet portion 152 a communicating with the nozzle inlet port 151 d of the nozzle 151, a refrigerant suction port 152 b from which refrigerant flowing out of a suction side evaporator (i.e., second evaporator) 18 is drawn, and a refrigerant outlet port 152 c from which the refrigerant drawn from the refrigerant suction port 152 b and the refrigerant jetted from the refrigerant jet port 151 e flow out as a mixed refrigerant.
The refrigerant inlet port 152 a is located at an outer peripheral side of the large-diameter portion 151 a of the nozzle 151, and is open in a direction perpendicular to the axial direction of the nozzle 151. The first refrigerant pipe 14 a is connected to the refrigerant inlet port 152 a so that the refrigerant flowing into the first refrigerant pipe 14 a from the branch portion 13 flows into the nozzle inlet port 151 d.
The refrigerant suction port 152 b is located in the body portion 152 at an outer peripheral side of the small-diameter portion 151 b of the nozzle 151, and is open in a direction perpendicular to the axial direction of the nozzle 151. Thus, the flow direction of the refrigerant drawn from the refrigerant suction port 152 b is not vertically crossed with the jet direction of the jet refrigerant jetted from the refrigerant jet port 151 e of the nozzle 151. A third refrigerant pipe 14 c (suction pipe) connected to the refrigerant outlet side of the second evaporator 18 is connected to the refrigerant suction port 152 b so that the refrigerant flowing out of the second evaporator 18 is drawn into the refrigerant suction port 152 b through the third refrigerant pipe 14 c.
The refrigerant outlet port 152 c is arranged coaxially with the nozzle 151, and is open in the axial direction of the nozzle 151. The diffuser 153 is connected to the refrigerant outlet port 152 c of the body portion 152. The first refrigerant pipe 14 a, the third refrigerant pipe 14 c and the diffuser 153 may be respectively formed from a metal pipe such as a copper pipe, and can be bonded respectively to the body portion 152 by brazing or the like.
The various refrigerant passages provided in the body portion 152 includes a refrigerant suction passage 152 d through which the refrigerant drawn from the refrigerant suction port 152 b is introduced toward the refrigerant injection port 151 e of the nozzle 151, and a cylindrical mixing passage 152 e provided continuously for the refrigerant suction passage 152 d, through which the mixed refrigerant is introduced to the refrigerant outlet port 152 c. Here, the mixed refrigerant is a mixture of the refrigerant jetted from the refrigerant jet port 151 e and the refrigerant drawn from the refrigerant suction port 152 b.
The refrigerant suction passage 152 d is configured by a suction inlet part 152 f from which the suction refrigerant from the refrigerant suction port 152 b flows, a suction space part 152 g through which the suction refrigerant introduced from the suction inlet part 152 f flows, and a suction outlet part 152 h through which the suction refrigerant from the suction space part 152 g flows into the mixing passage 152 e.
The suction inlet part 152 f is open in the same direction as the refrigerant suction port 152 b, such that the passage open area of the suction inlet part 152 f is smaller than the passage open area of the refrigerant suction port 152 b. For example, in the present embodiment, a ratio of the passage open area of the suction inlet part 152 f to the open area of the refrigerant suction port 152 b can be set equal to or smaller than 0.5.
As shown in FIG. 2, the passage open area of the suction inlet part 152 f is greatly smaller than the maximum passage open area of the third refrigerant pipe 14 c (suction refrigerant pipe). In the present embodiment, the suction inlet part 152 f is configured by an orifice. The suction inlet part 152 f may be configured by directly forming an orifice in the body portion 152, or may be configured by fitting another member having an orifice into the body portion 152.
The suction space part 152 g is approximately a cylindrical space provided at an outer peripheral side of the small-diameter portion 151 b of the nozzle 151. The suction refrigerant flowing from the suction inlet part 152 f changes its flow direction in the suction space part 152 g while passing through the suction space part 152 g. The refrigerant passage area (i.e., passage cross-sectional area) of the suction space part 152 g is larger than the refrigerant passage area (i.e., passage cross-sectional area) of the suction inlet part 152 f.
That is, the refrigerant passage area of the suction space part 152 g is a cross sectional area of the suction space part 152 g in a cross section perpendicular to the flow direction of the refrigerant flowing through the suction space part 152 g. Therefore, if the flow direction of the suction refrigerant flowing through the suction space part 152 g is changed, the refrigerant passage area of the suction space part 152 g is also changed.
In the present embodiment, the smallest refrigerant passage area in the refrigerant passage area of the suction space part 152 g is set larger than the refrigerant passage area of the suction inlet part 152 f. That is, the refrigerant passage area of the suction inlet part 152 f becomes smaller than the smallest refrigerant passage area of the suction space part 152 g. For example, a ratio of the refrigerant passage area of the suction inlet part 152 f to the smallest refrigerant passage area of the third refrigerant pipe 14 c (suction refrigerant pipe) is equal to or smaller than 0.5.
The suction outlet part 152 h is open in the axial direction of the nozzle 151, i.e., is open in the jet direction (arrow 100 in FIG. 2) of the jet refrigerant jetted from the refrigerant jet port 151 e, such that the refrigerant in the suction space part 152 g flows out of the suction outlet part 152 h as in the jet direction shown by arrow 100 in FIG. 2.
The suction outlet part 152 h is provided to have a refrigerant passage area that is smaller than the smallest refrigerant passage area of the suction space part 152 g. As an example, a ratio of the refrigerant passage area of the suction outlet part 152 h to the smallest refrigerant passage area of the suction space part 152 g is set equal to or smaller than 0.5.
The nozzle 151 is located such that the tip end portion of the small-diameter portion 151 b of the nozzle 151 can penetrate into the axial center part of the suction outlet part 152 h. Therefore, the suction outlet part 152 h has a ring-shaped passage around the tip end portion of the small-diameter portion 151 b of the nozzle 151.
The diffuser 153 is a pressurizing portion in which the flow speed of the refrigerant is decelerated and the pressure of the refrigerant is increased, in the ejector 15. The diffuser 153 can be formed by plastically deforming a metal pipe (copper pipe) such that the refrigerant passage area of the diffuser 153 is gradually increased as toward downstream. Thus, the refrigerant is decelerated and the pressure of the refrigerant is increased in the diffuser 153 so that the speed energy of the refrigerant is converted to the pressure energy of the refrigerant. As shown in FIG. 2, the refrigerant passage area is made substantially constant at the inlet side and the outlet side of the diffuser 153. As shown in FIG. 1, the refrigerant outlet side of the diffuser 153 is connected to the refrigerant inlet side of the first evaporator 16.
For example, the first evaporator 16 is a heat absorption heat exchanger in which the refrigerant flowing thereinto from the diffuser 153 is evaporated by absorbing heat from outside air blown by a blower fan 16 a. That is, the refrigerant flowing into the first evaporator 16 from the diffuser 153 is heat-exchanged with outside air blown by the blower fan 16 a, to be evaporated. The blower fan 16 a may be an electrical blower in which the fan rotational speed is controlled by the control voltage output from the electrical control portion. The refrigerant outlet side of the first evaporator 16 is coupled to the refrigerant suction port of the compressor 11.
As shown in FIG. 1, an electrical expansion valve 17 is connected to the second refrigerant pipe 14 b so that the second stream of the refrigerant branched at the branch portion 13 flows into the electrical expansion valve 17 through the second refrigerant pipe 14 b. The electrical expansion valve 17 is a decompression unit configured to decompress and expand the refrigerant flowing into the second refrigerant pipe 14 b. The operation of the electrical expansion valve 17 can be controlled by control signal output from the electrical control portion. As shown in FIG. 1, the electrical expansion valve 17 includes a valve portion 17 a, and a motor portion 17 b for controlling a valve open degree of the valve portion 17 a. The valve open degree of the valve portion 17 a is controlled by the motor portion 17 b based on the control signal output from the electrical control portion.
The second evaporator 18 (suction evaporator) is connected to a refrigerant outlet side of the valve portion 17 a of the electrical expansion portion 17. For example, the second evaporator 18 is a heat absorption heat exchanger in which the refrigerant flowing thereinto from the electrical expansion valve 17 is evaporated by absorbing heat from outside air after passing through the first evaporator 16 and blown by the blower fan 16 a. That is, the refrigerant flowing into the second evaporator 18 from the electrical expansion valve 17 is heat-exchanged with outside air blown by the blower fan 16 a, to be evaporated. In FIG. 1, the second evaporator 18 is located downstream from the first evaporator 16 in the air flow direction 200; however, the second evaporator 18 can be located separately from the first evaporator 16. The refrigerant outlet side of the second evaporator 18 is coupled to the refrigerant suction port 152 b of the ejector 15 via the third refrigerant pipe 14 c.
In the example of FIG. 1, the first evaporator 16 and the second evaporator 18 are configured by an integrated heat exchange unit with a fin and tube structure. For example, the first evaporator 16 and the second evaporator 18 are configured to have common heat exchange fins while having independent tube structures. In the integrated structure of the first evaporator 16 and the second evaporator 18, the tube structure in which the refrigerant flowing out of the ejector 15 flows and the tube structure in which the refrigerant flowing out of the electrical expansion valve 17 flows are provided independently from each other.
Thus, the heat of the air blown by the blower fan 16 a is absorbed first by the refrigerant at the first evaporator 16, and then is absorbed by the refrigerant at the second evaporator 18.
In the example of FIG. 1, the first evaporator 16 and the second evaporator 18 are arranged in series in the air flow direction 200, to be integrated. However, the first evaporator 16 and the second evaporator 18 separated from each other may be arranged in series in the air flow direction 200. Alternatively, the first evaporator 16 and the second evaporator 18 may be arranged separately from each other at different places.
Next, the electrical control portion of the refrigerant cycle device according to the first embodiment will be described. The electrical control portion is a control device configured by a microcomputer having therein a CPU, a ROM and a RAM and the like, and circumference circuits, which are generally known. The output side of the electrical control portion is connected to various actuators such as the electrical motor 11 b of the compressor 11, the driving portion 155 of the ejector 15, a motor of the blower fan 16 a, the electrical motor 17 b of the electrical expansion valve 17, and the like, so as to control the components.
The input side of the electrical control portion is connected to a sensor group, an operation panel and the like. The sensor group includes a water temperature sensor configured to detect a temperature of the heated water at the water outlet side of the water passage 12 a of the water-refrigerant heat exchanger 12, an outside air temperature sensor configured to detect a temperature of air (e.g., outside air) blown by the blower fan 16 a. The operation panel is connected to the input side of the electrical control portion so that operation signals such as a start signal and a stop signal of the water heater 1 and a water temperature setting signal of the water heater 1 are input to the electrical control portion.
Next, operation of the heat pump water heater 1 according to the first embodiment will be described. When electrical power is supplied from an exterior of the heat-pump water heater 1 and an operation start signal of the water heater 1 is input from the operation panel to the electrical control portion, the electrical control portion performs a predetermined control program stored in the ROM, and thereby the components 11 b, 155, 16 a, 17, 22 and the like of the refrigerant cycle device 10 are operated.
High-temperature and high-pressure refrigerant discharged from the compressor 11 flows into the refrigerant passage 12 b of the water-refrigerant heat exchanger 12 to perform heat exchange with water flowing into the water passage 12 a of the water-refrigerant heat exchanger 12 from a lower side in the water tank 21. Water is introduced by the electrical pump 22 from the lower side in the water tank 21 into the water passage 12 a, and is heat-exchanged with the high-temperature high-pressure refrigerant flowing through the refrigerant passage 12 b in the water-refrigerant heat exchanger 12. Thus, water is heated while passing through the water passage 12 a of the water-refrigerant heat exchanger 12, and the heated water is stored at an upper side in the water tank 21.
The high-pressure refrigerant flowing out of the refrigerant passage 12 b of the water-refrigerant heat exchanger 12 flows into the refrigerant branch portion 13 and is branched into the first stream and the second stream. The refrigerant of the first stream branched at the branch portion 13 flows into the nozzle portion 151 of the ejector 15 via the first refrigerant pipe 14 a, and is decompressed in the nozzle 151 in iso-entropy. The refrigerant decompressed in iso-entropy in the nozzle 151 is jetted from the refrigerant jet port 151 e by a high speed.
The driving portion 155 of the ejector 15 is controlled by control signal output from the electrical control portion so as to control the refrigerant passage areas of the refrigerant passage 151 c and the refrigerant jet port 151 e of the ejector 15, such that the super-heat degree of the refrigerant drawn into the compressor 11 is approached to a predetermined value. Thus, it can prevent liquid refrigerant from being returned to the compressor 11.
The refrigerant flowing out of the second evaporator 18 is drawn into the ejector 15 from the refrigerant suction port 152 b. Furthermore, the jet refrigerant jetted from the refrigerant jet port 151 e and the suction refrigerant drawn from the refrigerant suction port 152 b are mixed at an inlet side of the mixing passage 152 e and the mixing passage 152 e, and then the mixed refrigerant flows into the diffuser 153.
Because the passage area of the diffuser 153 is gradually increased toward downstream, the refrigerant pressure is increased by converting the speed energy of the refrigerant to the pressure energy of the refrigerant. The refrigerant flowing out of the diffuser 153 of the ejector 15 flows into the first evaporator 16 and is evaporated by absorbing heat from outside air blown by the blower fan 16 a. Then, the refrigerant flowing out of the first evaporator 16 is drawn into the compressor 11 and is compressed in the compressor 11.
The refrigerant of the second stream branched at the branch portion 13 is decompressed and expanded at the electrical expansion valve 17, and then flows into the second evaporator 18. The refrigerant flowing into the second evaporator 18 is evaporated by absorbing heat from the outside air, and the evaporated gas refrigerant flowing out of the second evaporator 18 is drawn into the ejector 15 from the refrigerant suction port 152 b.
The throttle passage area (i.e., valve open degree) of the electrical expansion valve 17 is changed in accordance with a control signal output from the electrical control portion, such that the refrigerant pressure on the high pressure side of the refrigerant cycle before being decompressed is approached to a target pressure. The target pressure is determined based on the temperature of the refrigerant flowing out of the refrigerant passage 12 b of the water-refrigerant heat exchanger 12 such that the coefficient of performance (COP) of the refrigerant cycle is approached to approximately the maximum value. Thus, the refrigerant cycle device 10 can be operated with a high value of the COP.
In the refrigerant cycle device 10, the refrigerant pressurized in the diffuser 153 flows into the first evaporator 16. In contrast, because the second evaporator 18 is connected to the refrigerant suction port 152 b, the refrigerant evaporation pressure in the second evaporator 18 corresponds to the lowest pressure immediately after the refrigerant jet port 151 e of the nozzle 151.
Thus, the refrigerant evaporation pressure (refrigerant evaporation temperature) in the second evaporator 18 can be made lower than the refrigerant evaporation pressure (refrigerant evaporation temperature) in the first evaporator 16. As a result, even when the second evaporator 18 is located downstream from the first evaporator 16 in the air flow direction 200, a suitably temperature difference between the refrigerant and air blown by the blower fan 16 a can be set at both the first evaporator 16 and the second evaporator 18, and thereby the refrigerant can effectively absorb heat from air at both the first evaporator 16 and the second evaporator 18.
In the present embodiment, the refrigerant suction passage 152 d is configured by the suction inlet part 152 f, the suction space part 152 g and the suction outlet part 152 h. Next, the configuration of the ejector 15 including the refrigerant suction passage 152 d will be described.
In the present embodiment, because the refrigerant passage area of the suction inlet part 152 f is made smaller than the open area of the refrigerant suction port 152 b, a flow speed of the suction refrigerant flowing from the suction inlet part 152 f to the suction space part 152 g can be increased than a flow speed of the suction refrigerant drawn through the refrigerant suction port 152 b. Thus, it is possible to effectively increase the dynamical pressure of the suction refrigerant flowing into the suction space part 152 g from the suction inlet part 152 f.
Because the refrigerant flowing into the suction space part 152 g is disturbed due to the dynamical pressure, the refrigerant flowing into the suction space part 152 g can be effectively mixed to be uniform. Furthermore, because the flow speed of the suction refrigerant (suction fluid) after flowing into the suction space part 152 g is decreased than the flow speed of the suction refrigerant (suction fluid) at the time of just flowing into the suction space part 152 g from the suction inlet part 152 f, the dynamical pressure of the suction refrigerant is converted to the static pressure. Thus, the suction space part 152 g can be used for equalizing the pressure of the refrigerant flowing out of the suction outlet part 152 h, and thereby the flow speed difference in the flow speed distribution can be reduced.
Furthermore, because the flow passage area (i.e., flow passage sectional area) of the suction outlet part 152 h is smaller than that of the suction space part 152 g, it can prevent the refrigerant from flowing out of the suction outlet part 152 h before the flow speed difference in the flow speed distribution is reduced.
Accordingly, the mixing pressure loss caused while the jet refrigerant and the suction refrigerant are mixed can be reduced, thereby the pressurizing amount in the mixing passage 152 e and the diffuser 153 can be increased. Thus, the power consumed in the compressor 11 can be reduced, thereby increasing the COP in the refrigerant cycle.
In the present embodiment, because the suction inlet part 152 f is configured by an orifice, the flow speed of the refrigerant flowing from the suction inlet part 152 f into the suction space part 152 g can be effectively made faster than the flow speed of the refrigerant drawn from the refrigerant suction port 152 b into the suction inlet part 152 f. Therefore, the length of the refrigerant suction passage 152 d can be relatively reduced.
Because the cylindrical suction space part 152 g is provided at an outer peripheral side of the nozzle 151, the suction refrigerant can be uniformly mixed in the entire outer peripheral side of the jet refrigerant, thereby effectively reducing the mixing pressure loss.
The suction outlet part 152 h communicating with the cylindrical suction space part 152 g around the small-diameter portion 151 b of the nozzle 151 is provided upstream of the mixing passage 152 e, and the refrigerant jet port 151 e of the nozzle 151 is located at the radial center area of the suction outlet part 152 d. Therefore, the refrigerant drawn from the suction inlet part 152 f is turned in the cylindrical suction space part 152 g and then flows to the suction outlet part 152 h. Thus, a flow direction of the refrigerant from the suction space part 152 g into the suction outlet part 152 h substantially corresponds to the jet direction 100 of the refrigerant jetted from the refrigerant jet port 151 e into the mixing passage 152 e via the suction outlet part 152 h. Accordingly, the mixing pressure loss can be more effectively reduced.
In the first embodiment, the present invention is applied to the ejector 15 in which the flow direction of the suction refrigerant drawn from the refrigerant suction port 152 b is substantially crossed perpendicularly with an extension line of the jet direction 100 of the refrigerant jetted from refrigerant jet port 151 e. In this case, the mixing pressure loss, caused while the jet refrigerant and the suction refrigerant are mixed in the ejector 15, can be more effectively reduced.

Second Embodiment

A second embodiment of the present invention will be described with reference to FIG. 3. In the above-described first embodiment, the third refrigerant pipe (suction refrigerant pipe) 14 c connected to the refrigerant suction port 152 b is a general pipe having a constant passage area. However, in the second embodiment, as shown in FIG. 3, the third refrigerant pipe (suction refrigerant pipe) 14 c connected to the refrigerant suction port 152 b is configured to have a passage sectional area gradually reduced toward the refrigerant suction port 152 b.
In the second embodiment, the passage sectional area of the suction inlet part 152 f is made smaller than the passage sectional area of the third refrigerant pipe 14 c. Thus, the passage sectional area of the suction inlet part 152 f is smaller than the maximum passage sectional area of the third refrigerant pipe 14 c. As an example of the second embodiment, the passage sectional area of the suction inlet part 152 f can be made smaller than the minimum passage sectional area of the third refrigerant pipe 14 c. In the second embodiment, the other parts of the ejector 15 can be similar to those of the ejector 15 of the first embodiment.
According to the second embodiment of the present invention, when the heat pump water heater 1 is operated, the flow speed of the refrigerant passing through the third refrigerant pipe 14 c is gradually increased as toward the refrigerant suction port 152 b. Thus, the dynamical pressure of the refrigerant flowing from the suction inlet port 152 f into the suction space part 152 g can be increased.
As a result, a difference of the flow speed in the flow speed distribution of the suction refrigerant flowing out of the suction outlet part 152 h can be reduced, thereby reducing the mixing pressure loss caused while the jet refrigerant and the suction refrigerant are mixed. Furthermore, the flow speed of the refrigerant flowing through the third refrigerant pipe 14 c is gradually increased, thereby reducing the noise generation.
Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art.
In the ejector 15 of the above-described embodiments, the flow direction of the suction refrigerant drawn from the refrigerant suction port 152 b is crossed perpendicularly with the extension line of the jet direction 100 of the jet refrigerant jetted from the refrigerant jet port 151 e of the nozzle 151. However, the flow direction of the suction refrigerant drawn from the refrigerant suction port 152 b and the jet direction 100 of the jet refrigerant jetted from the refrigerant jet port 151 e of the nozzle 151 may be set at directions to be different from each other.
For example, because the flow direction of the suction refrigerant flowing from the suction inlet part 152 f is changed in the suction space part 152 g and then the refrigerant in the suction space part 152 g flows out of the suction outlet part 152 h, the mixing pressure loss can be effectively reduced.
In the above-described embodiments, the refrigerant passage area of the nozzle 151 is changed such that the super-heat degree of the refrigerant on the refrigerant outlet side of the first evaporator 16 becomes in a target super-heat degree, and the throttle passage area of the electrical expansion valve 17 is changed such that the refrigerant pressure on the high-pressure side in the refrigerant cycle becomes a target value. However, the control of the nozzle 151 and the control of the electrical expansion valve 17 can be performed reversely.
That is, the throttle passage area of the electrical expansion valve 17 can be changed such that the super-heat degree of the refrigerant on the refrigerant outlet side of the first evaporator 16 becomes in the target super-heat degree, and the refrigerant passage area of the nozzle 151 is changed such that the refrigerant pressure on the high-pressure side in the refrigerant cycle becomes a target value.
In the above-described embodiments, the carbon dioxide is used as the refrigerant. However, a generally known fluid such as carbon hydride refrigerant, a flon-based refrigerant can be used. Furthermore, the ejector 15 of the above-described embodiments can be used for a sub-critical refrigerant cycle device in which the refrigerant pressure on the high-pressure side is lower than the critical pressure of the refrigerant.
In the above-described embodiments, an electrical compressor is used as the compressor 11. However, a generally known compressor such as a compressor driven by the engine or the like may be used as the compressor 11. Furthermore, as the compression mechanism 11 a, a fixed-displacement compression mechanism or a variable-displacement compression mechanism may be used.
In the above-described embodiments, the nozzle 151 is a variable nozzle configured such that the refrigerant passage of the nozzle 151 can be changed. However, the nozzle 151 may be not a variable nozzle configured such that the refrigerant passage of the nozzle 151 is fixed.
In the above-described embodiments, the refrigerant cycle device 10 is used for the heat-pump water heater 1. However, the refrigerant cycle device 10 may be used for a fixed-type air conditioner, a vehicle air conditioner or the like. In this case, the first evaporator 16 and the second evaporator 18 can be used as an interior heat exchanger, and a radiator (12) is used as an exterior heat exchanger.
Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims.

Claims

1. An ejector comprising:

a nozzle configured to decompress and jet a fluid;

a body portion having a fluid suction port from which a fluid is drawn by a jet flow of the fluid jetted from the nozzle, and a fluid suction passage through which the fluid drawn from the fluid suction port flows while a flow direction of the fluid drawn from the fluid suction port is changed; and

a pressurizing portion in which a pressure of a fluid mixture between the fluid flowing through the fluid suction passage from the fluid suction port and the fluid jetted from the nozzle is increased, wherein

the fluid suction passage is configured to have a suction inlet part into which the fluid from the fluid suction port flows, a suction space part in which the flow direction of the fluid flowing from the fluid suction port is changed, and a suction outlet part from which the fluid from the suction space part flows out in a jet direction of the jet fluid,

the suction inlet part has a fluid passage area that is smaller than an open area of the fluid suction port and a fluid passage area of the suction space part, and

the fluid passage area of the suction outlet part is smaller than the fluid passage area of the suction space part.

2. The ejector according to claim 1, wherein

the fluid suction port is connected to a fluid suction pipe in which the fluid to be drawn into the fluid suction port flows, and

the fluid passage area of the suction inlet part is smaller than a fluid passage area of the fluid suction pipe.

3. The ejector according to claim 2, wherein the fluid passage area of the fluid suction pipe is gradually reduced as toward the fluid suction port.

4. The ejector according to claim 1, wherein the suction inlet part is an orifice.

5. The ejector according to claim 1, wherein an extending line of a flow direction of the fluid drawn from the fluid suction port is crossed perpendicularly with an extending line of the jet direction of the fluid jetted from the nozzle.

6. The ejector according to claim 1, wherein the suction space part is provided on an outer peripheral side of the nozzle.

7. The ejector according to claim 1, wherein a ratio of the fluid passage area of the suction inlet part to the open area of the fluid suction port is equal to or smaller than 0.5.

8. The ejector according to claim 2, wherein a ratio of the fluid passage area of the suction inlet part to the maximum fluid passage area of the fluid suction pipe is equal to or smaller than 0.5.

9. The ejector according to claim 1, wherein a ratio of the fluid passage area of the suction outlet part to the fluid passage area of the suction space part is equal to or smaller than 0.5.

10. The ejector according to claim 1, wherein

the suction space part is an approximately cylindrical passage provided on the outer peripheral side of the nozzle to extend in an axial direction of the nozzle, and

the suction outlet part extends coaxially with the cylindrical passage of the suction space part and is tapered downstream.

11. The ejector according to claim 10, wherein

the nozzle is located to protrude into the suction outlet part from the suction space part coaxially with the cylindrical passage, and

the suction inlet part is open to the cylindrical passage in a direction approximately perpendicular to the axial direction of the nozzle.

12. The ejector according to claim 1, further comprising

a cylindrical mixing passage provided between the suction outlet part and the diffuser coaxially.

13. An ejector comprising:

a nozzle configured to decompress and jet a fluid;

the fluid suction port is connected to a fluid suction pipe in which the fluid to be drawn into the fluid suction port flows,

the suction inlet part has a fluid passage area that is smaller than a fluid passage area of the fluid suction pipe and a fluid passage area of the suction space part, and

14. The ejector according to claim 13, wherein

the fluid passage area of the fluid suction pipe is gradually reduced as toward the fluid suction port, and

the fluid passage area of the suction inlet part is smaller than the smallest fluid passage area of the fluid suction pipe.