US20080060378A1

US20080060378A1 - Ejector and refrigerant cycle device with ejector

Info

Publication number: US20080060378A1
Application number: US11/899,568
Authority: US
Inventors: Mika Gocho; Hirotsugu Takeuchi; Yoshiaki Takano; Hiroshi Oshitani; Yasuhiro Yamamoto
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2006-09-07
Filing date: 2007-09-06
Publication date: 2008-03-13
Also published as: JP2008064021A; DE102007041943A1; JP4929936B2

Abstract

An ejector for a refrigerant cycle device includes a nozzle portion for decompressing and expanding refrigerant flowing therein, and a body portion which accommodates the nozzle portion to support the nozzle portion at a support portion. The body portion has a refrigerant suction port from which refrigerant is drawn by a high-speed refrigerant flow jetted from a nozzle outlet of the nozzle portion. The nozzle portion is located in the body portion to have an ejector refrigerant passage through which the refrigerant flows. In the ejector, the nozzle portion is supported in the body portion to have the following relationship of 0<L/d≦14, in which L/d is a ratio of a length (L) between a downstream tip portion of the support portion and the nozzle outlet to a diameter (d) of the nozzle outlet.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2006-242512 filed on Sep. 7, 2006, the contents of which are incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to an ejector and a refrigerant cycle device having the ejector.
2. Description of the Related Art
Refrigerant cycle devices having an ejector are described in JP-A-2005-308380 (corresponding to U.S. Pat. No. 7,178,359) and JP-A-2004-270460 (corresponding to US 2004/0172966 A1), for example.
FIG. 18 shows an ejector 14 for a refrigerant cycle device in a related art. The ejector 14 includes a nozzle portion 14 a for decompressing refrigerant from a radiator, a refrigerant suction port 14 d from which refrigerant is drawn by a high-speed refrigerant flow jetted from a nozzle outlet of the nozzle portion 14 a, a mixing portion 14 b for mixing the refrigerant jetted from the nozzle portion 14 a and the refrigerant drawn from the refrigerant suction port 14 d, and a diffuser 14 c. The nozzle portion 14 a is supported by a body portion 14 e, and the refrigerant suction port 14 d is provided in the body portion 14 e.
In a general operation of the refrigerant cycle device, vapor refrigerant evaporated in an evaporator is drawn into the ejector 14 through the refrigerant suction port 14 d, and is mixed with the driving refrigerant flow jetted from the nozzle portion 14 a in the mixing portion 14 b. However, if the refrigerant cycle device is operated in a state where the ejector 14 is operated only with the driving refrigerant flow jetted from the nozzle portion 14 a without the suction refrigerant flow from the refrigerant suction port 14 d, the driving refrigerant flow jetted from the nozzle portion 14 a is turned to cause vortex flow at the nozzle outlet side, thereby increasing the jet flow loss due to the vortex flow shown by the arrows V. The vortex flow V is also caused when the amount of the suction refrigerant flow drawn from the refrigerant suction port 14 d is small. When the jet flow loss due to vortex flow V is increased, the outlet side of the nozzle portion 14 a and the body portion 14 e near the nozzle outlet of the nozzle portion 14 a are vibrated, thereby increasing the refrigerant passing noise. In addition, if the length L from a downstream tip end of the nozzle support portion to the nozzle outlet is long in the ejector 14, the vibration of the ejector 14 is more easily caused.
Furthermore, when the ejector 14 is used for a refrigerant cycle device having a first evaporator located downstream of the ejector 14 and a second evaporator located in a branch passage branched from a refrigerant passage at an upstream side of the nozzle portion 14 a and joined to the refrigerant suction port 14 d, the refrigerant passing noise generated in the ejector 14 is more easily increased if the amount of the suction refrigerant flow from the second evaporator to the refrigerant suction port 14 d is small or zero.

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 the loss due to vortex flow at a nozzle outlet side so as to reduce refrigerant passing noise.
It is another object of the present invention to provide a refrigerant cycle device with an ejector, which can reduce refrigerant passing noise.
According to an example of the present invention, an ejector for a refrigerant cycle device includes a nozzle portion for decompressing and expanding refrigerant flowing therein, and a body portion which accommodates the nozzle portion to support the nozzle portion at a support portion. The body portion has a refrigerant suction port from which refrigerant is drawn by a high-speed refrigerant flow jetted from a nozzle outlet of the nozzle portion. The nozzle portion is located in the body portion to have an ejector refrigerant passage through which the refrigerant jetted from the nozzle outlet of the nozzle portion and the refrigerant drawn from the refrigerant suction port flow. In addition, the nozzle portion is supported in the body portion to have the following relationship of 0<L/d≦14, in which L/d is a ratio of a length (L) between a downstream tip portion of the support portion and the nozzle outlet to a diameter (d) of the nozzle outlet. Accordingly, a distance between the tip end (nozzle outlet) of the nozzle portion and the support portion where the nozzle portion is supported by the body portion can be shortened, thereby reducing vibration of the nozzle portion and the body portion.
The body portion has a mixing portion in which the refrigerant jetted from the nozzle outlet and the refrigerant drawn from the refrigerant suction port are mixed. For example, the mixing portion may have a wall thickness (t) and an inner diameter (D), and a ratio t/D of the wall thickness (t) to the inner diameter (D) may be equal to or larger than 0.2. In this case, the vibration of the ejector can be further reduced.
For example, the nozzle portion may have a first part, a second part downstream from the first part in a refrigerant flow of the nozzle portion and positioned to correspond to an area of the refrigerant suction port, and a third part downstream from the second part in the refrigerant flow of the nozzle portion. In this case, the first part of the nozzle portion may be supported by the body portion at the support portion.
Alternatively, the third part of the nozzle portion may be supported by the body portion at the support portion. In this case, the nozzle portion may have a protrusion portion protruding from an outer wall surface of the third part of the nozzle portion toward the body portion, and the protrusion portion of the nozzle portion may contact an inner wall of the body portion to form the support portion. Alternatively, the body portion may have a protrusion portion protruding from an inner wall of the body portion to the nozzle portion at a position corresponding to the third part of the nozzle portion, and the protrusion portion of the body portion may contact an outer wall of the nozzle portion to form the support portion.
Alternatively, a support member may be located between an inner wall of the body portion and an outer wall of the third part of the nozzle portion. In this case, the nozzle portion may be supported in the body portion by the support member.
Furthermore, the nozzle portion may be movable by a driving portion between a first state where an outer wall of the nozzle portion is spaced from an inner wall of the body portion such that the refrigerant drawn from the refrigerant suction port flows, and a second state where the outer wall of the nozzle portion contacts the inner wall of the body portion to be supported by the body portion at the support portion such that a refrigerant flow from the refrigerant suction port is closed.
According to another example of the present invention, an ejector for a refrigerant cycle device includes a nozzle portion having therein a nozzle passage in which high-pressure refrigerant before being decompressed flows, and a body portion which accommodates the nozzle portion. The nozzle portion has an approximately cylindrical outer wall portion and a nozzle outlet from which the refrigerant decompressed in the nozzle passage is jetted, and a suction passage is provided between the nozzle portion and the body portion to extend from the cylindrical outer wall portion of the nozzle portion to the nozzle outlet. The body portion has a refrigerant suction port that is opened radially outwardly of the cylindrical outer wall portion to communicate with the suction passage. In addition, the ejector further includes a first fixing member for connecting and fixing the nozzle portion to the body portion at a position upstream from the refrigerant suction port in a refrigerant flow of the nozzle passage, and a second fixing member for connecting and fixing the nozzle portion to the body portion at a position downstream from the refrigerant suction port in the refrigerant flow of the nozzle passage. Therefore, the distance between the tip end (nozzle outlet) of the nozzle portion to the second fixing member as the support portion can be shortened, thereby reducing vibration of the nozzle portion. Thus, the refrigerant passing noise can be effectively reduced even when the vortex flow is caused at the side of the nozzle outlet in a case where the ejector is operated with a refrigerant driving flow in the nozzle portion without a refrigerant suction flow from the refrigerant suction port or a very small refrigerant suction flow.
A mixing portion of the ejector may have approximately a uniform wall thickness (t) and a uniform inner diameter (D), and a ratio t/D of the wall thickness (t) to the inner diameter (D) may be equal to or larger than 1. In this case, vibration of the body portion around the nozzle outlet can be further reduced.
The ejector can be suitably used for a refrigerant cycle device in which high-pressure refrigerant is decompressed at the nozzle portion of the ejector.

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 an example of a refrigerant cycle device according to embodiments of the present invention;

FIG. 2A is a sectional view showing a part of an ejector according to a first embodiment of the present invention, and FIG. 2B is an enlarged sectional view showing the part IIB in FIG. 2A;

FIG. 3 is a sectional view showing a fixing method of a nozzle portion and a body portion in the ejector according to the first embodiment;

FIG. 4 is a graph showing the relationship between a noise level difference and a ratio L/d of a distance L between a downstream tip portion of the nozzle support portion and a nozzle outlet to a nozzle outlet diameter d, according to the first embodiment;

FIG. 5 is a graph showing the relationship between the noise level difference and a ratio t/D of a body wall thickness t to an inner diameter D of the mixing portion, according to the first embodiment;

FIG. 6 is a sectional view showing a part of an ejector according to a first example of a second embodiment of the present invention;

FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. 6;

FIG. 8 is a sectional view showing a part of an ejector according to a second example of the second embodiment of the present invention;

FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG. 8;

FIG. 10 is a sectional view showing a part of an ejector according to a third example of the second embodiment of the present invention;

FIG. 11 is a cross-sectional view taken along the line XI-XI in FIG. 10;

FIG. 12 is a sectional view showing an ejector according to a third embodiment of the present invention;

FIG. 13 is an enlarged sectional view showing a part XIII of the ejector in FIG. 12 when the ejector has therein a refrigerant suction flow;

FIG. 14 is an enlarged sectional view showing the part XIII of the ejector in FIG. 12 when the ejector has no refrigerant suction flow;

FIG. 15 is a sectional view showing a part of an ejector according to a fourth embodiment of the present invention;

FIG. 16 is a cross-sectional view taken along the line XVI-XVI in FIG. 15;

FIG. 17 is a sectional view showing a part of an ejector according to another embodiment of the present invention; and

FIG. 18 is a sectional view showing a part of an ejector in a related art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

FIG. 1 is a schematic diagram showing an example of a refrigerant cycle device with an ejector 1 of a first embodiment. The operation of the refrigerant cycle device with the ejector 1 may be similar to that of U.S. Pat. No. 7,178,359, which are incorporated by reference.
As shown in FIG. 1, the refrigerant cycle device includes a compressor 12 for drawing and compressing refrigerant, a radiator 13 for cooling high pressure refrigerant discharged from the compressor 12, a refrigerant circulation path 11 for introducing the refrigerant flowing out of the radiator 13 into a nozzle portion 2 of the ejector 1, a first evaporator 15 for evaporating the refrigerant flowing out of the ejector 1, and a branch passage 16 branched from the refrigerant circulation path 11 at a position upstream from the nozzle portion 2 and downstream from the radiator 13. A downstream end of the branch passage 16 is coupled to a refrigerant suction port 3 a of the ejector 1. An electromagnetic valve 20 is located in the branch passage 16 to interrupt a refrigerant flow to the second evaporator 18, and a flow adjusting valve 17 is located to decompress refrigerant flowing into the second evaporator 18 and to adjust a flow amount of the refrigerant flowing into the second evaporator 18. The electromagnetic valve 20 and the flow adjusting valve 17 may be integrated as one unit.
In the example of FIG. 1, the refrigerant outlet of the first evaporator 15 can be directly coupled to a refrigerant suction side of the compressor 12. However, a vapor-liquid separator may be located between the first evaporator 15 and the refrigerant suction side of the compressor 12. The first evaporator 15 may be singly operated when the refrigerant flow to the second evaporator 18 is shut by the electromagnetic valve 20, or both the first evaporator 15 and the second evaporator 18 may be simultaneously operated. The operation of the refrigerant cycle device with the ejector 1 is generally known, and the detail explanation thereof is omitted. In this embodiment, the first evaporator 15 and the second evaporator 18 may be located to cool a single compartment to be cooled or may be located to cool different compartments to be cooled.
Next, the structure of the ejector 1 will be described.
As shown in FIG. 2A, the ejector 1 of this embodiment includes the nozzle portion 2 and a body portion 3 which is disposed to support the nozzle portion 2. The nozzle portion 2 has therein a nozzle passage 2 a for decompressing and expanding high-pressure refrigerant from the radiator 13. The nozzle portion 2 is adapted to isentropically decompress and expand high-pressure refrigerant by decreasing the passage sectional area of the nozzle passage 2 a to a small level, and by ejecting high-speed refrigerant from a nozzle outlet (nozzle tip) 2 b. The refrigerant at the nozzle outlet 2 b is decompressed partially so called as a middle-pressure refrigerant that is close to and could be categorized as a low-pressure refrigerant. The nozzle portion 2 may be referred to as a functional member that ejects the high-pressure refrigerant into a low-pressure region in the refrigerant cycle.
The body portion 3 has a cylindrical shape on its outer wall surface. The nozzle portion 2 is disposed inside the body portion 3. The body portion 3 has the refrigerant suction port 3 a located in the same space as the nozzle outlet 2 b of the nozzle portion 2, for sucking the vapor-phase refrigerant from the second evaporator 18 thereinto by the high-velocity refrigerant flow ejected from the nozzle outlet 2 b of the nozzle portion 2. The body portion 3 constitutes ejector flow passages for the sucked flow of the refrigerant from the refrigerant suction port 3 a, and the refrigerant driving flow jetted from the nozzle outlet 2 b. That is, the body portion 3 includes a suction path portion 3 b serving as a flow path of the sucked flow of the refrigerant from the refrigerant suction port 3 a, and a mixing portion 3 c and a diffuser 3 d which serve as a flow path for the mixed flow into which the sucked refrigerant flow from the refrigerant suction port 3 a and the driving refrigerant flow ejected from the nozzle portion 2 are mixed. The diffuser 3 d is formed in such a shape to gradually increase the passage area of the refrigerant, and is provided to decelerate the refrigerant flow and to increase the refrigerant pressure, that is, to convert the velocity energy of the refrigerant into the pressure energy.
The nozzle portion 2 and the body portion 3 are constructed of different components, that is, individual structures. The nozzle portion 2 is made of metal, such as, stainless or brass, and the body portion 3 is made of metal, such as aluminum, for example.
FIG. 2B is an enlarged view of the area enclosed by the broken line IIB shown in FIG. 2A. The ejector 1 of this embodiment has such a structure that the nozzle portion 2 is supported by the body portion 3 near the nozzle outlet 2 b, as compared to that in a conventional ejector.
As shown in FIG. 2B, the nozzle portion 2 has an elongated shape extending linearly, and has such a contour that the outer diameter of a first part 2 d (nozzle support portion) on the upstream side of the driving flow is larger than that of a second part 2 c (nozzle un-support portion) opposed to the refrigerant suction port 3 a. That is, the second part 2 c is the part corresponding to the refrigerant suction port 3 a in a refrigerant flow of the nozzle portion 2. The nozzle portion 2 has an outer wall of the first part 2 d on the upstream side of the refrigerant driving flow, such that the first part 2 d is in contact with the inner wall of the body portion 3, and the part on the nozzle outlet 2 b side from the first part 2 d is not in contact with the body portion 3. That is, in the nozzle portion 2, the first part 2 d on the driving flow upstream side is supported by the body portion 3, rather than the second part 2 c that is opposed to the refrigerant suction port 3 a. In this embodiment, the position of a downstream tip portion 2 e of the nozzle support portion (first part 2 d) of the nozzle portion 2, supported by the body portion 3, is approximately identical to that of an end of the refrigerant suction port 3 a. It is noted that these positions may not necessarily be identical to each other.
Regarding the dimension of the nozzle portion 2, a length L from the downstream tip portion 2 e of the first part 2 d to the nozzle outlet 2 b is set such that the ratio L/d of the length L to the nozzle outlet diameter d is 14 or less.
The tip portion 2 e of the first part 2 d is a nozzle outlet side end located within the range of the nozzle portion 2 supported by the body portion 3. The length L means a linear distance in the extending direction of the nozzle portion 2, in other words, in the axial direction of the nozzle portion 2, or in the flow direction of the driving flow of the refrigerant. The nozzle outlet diameter d means the inner diameter of the nozzle at the nozzle outlet 2 b. The sectional shape of the flow path at the nozzle outlet 2 b is not limited to a circular. When the sectional shape of the flow path at the nozzle outlet 2 b is not circular, the nozzle outlet diameter may be the maximum dimension of a nozzle aperture at the nozzle outlet 2 b.
For example, L/d=1. That is, the length L may be the same as the nozzle outlet diameter d. The lower limit of the L/d is the minimum value that can be implemented and which has only to be larger than zero.
In the ejector 1 of this embodiment, a part of the body portion 3 near the nozzle outlet 2 b, that is, the mixing portion 3 c has a thickness larger than that the other part, as shown in FIG. 2A, as will be described later.
As shown in FIG. 2B, the body portion 3 is constructed of a single component, in which a suction portion 3 b and a mixing portion 3 c are integrally formed. The body portion 3 has a cylindrical outer shape without any stepped portions on the outer wall in the axial direction. The suction portion 3 b of the body portion 3 has a different inner diameter than that of the mixing portion 3 c thereof. That is, the thickness of the suction portion 3 b is different from that of the mixing portion 3 c, so as to set the refrigerant flow path sections of the suction portion 3 b and the mixing portion 3 c to desired sizes.
The mixing portion 3 c is an area where the refrigerant driving flow and the refrigerant suction flow are mixed. The mixing portion 3 c is disposed on the downstream side of the refrigerant flow from the nozzle outlet 2 b in the body portion 3, with the sectional area of the refrigerant flow path being constant. In this embodiment, all the area of the mixing portion 3 c has the constant thickness in the body portion 3.
The size of the body portion 3 is set to satisfy the following relationship that the ratio t/D of the body thickness t to the inner diameter D of the body portion 3 at the mixing portion 3 c is 1.0 or more. Here, the body thickness t is the wall thickness of the body portion 3 at the mixing portion 3 c.
In this embodiment, the position of the nozzle outlet 2 b is identical to that of the inlet of the mixing portion 3. Although theses positions are not identical to each other, the body thickness t on the downstream side of the refrigerant flow of the body portion 3 away from the nozzle outlet 2 b may be more preferable when the t/D is 1.0 or more.
Now, a method of manufacturing the ejector 1 with the above-described structure will be described below. FIG. 3 is a sectional view for explaining a method for fixing the nozzle portion 2 to the body portion 3.
The nozzle portion 2 and the body portion 3 are respectively manufactured, for example, by die-casting of metal parts, and then by cutting the parts, for example, by drilling. The nozzle portion 2 is inserted into the body portion 3 as indicated by the arrow shown by a solid line in FIG. 3, so that the nozzle portion 2 is pressed and fixed into the body portion 3. Alternatively, the nozzle portion 2 is caulked and fastened to the body portion 3 as indicated by the arrow shown by a broken line in FIG. 3. This can manufacture the ejector 1 with the above-described structure.
Now, the ejector 1 in this embodiment will be described below in detail.
(1) As mentioned above, in this embodiment, the position of a part of the nozzle portion 2 supported by the body portion 3 b, that is, the nozzle support position can be located near the nozzle outlet 2 b, thereby reducing the vibration of the nozzle portion 2 at a position near the nozzle outlet 2 b where the refrigerant flow velocity is fastest.
Accordingly, it is possible to restrain an increase in noise occurring when the refrigerant passes in a case where the refrigerant cycle device is in an operational state only of the refrigerant driving flow without the refrigerant suction flow, or in a case where the refrigerant cycle device is in an operational state of an extremely little refrigerant suction flow with respect to the refrigerant driving flow.
FIG. 4 shows a relationship between a difference in noise level of the ejector between the presence and absence of the refrigerant suction flow, and the ratio L/d of the length L to the nozzle outlet diameter d. Here, the length L is a length from the tip portion 2 e of the first part 2 d to the nozzle outlet 2 b in the axial direction. FIG. 4 shows the result of measurement obtained when the ratio t/D of the body thickness t to the inner diameter D of the mixing portion is 0.2 in the ejector 1 shown in FIG. 2B. The difference in noise level (noise level difference) represented in the longitudinal axis of FIG. 4 is obtained by performing frequency correction.
As shown in FIG. 4, as the L/d is decreased from about 20 to about 5, the difference in noise level tends to decrease. When the L/d is smaller than about 5, the difference in noise level further decreases. When the L/d is zero, it is estimated that the difference in noise level is closest to zero.
It is generally known that the lower limit of a sound pressure level recognized by human being is 3 dB. When the difference in noise level is equal to or less than 3 dB, the difference in sound between the presence and absence of the refrigerant suction flow hardly exists.
FIG. 4 shows that when the L/d is 14, the difference in noise level is about 3 dB. Thus, as can be seen from the above, when the L/d is greater than zero and not more than 14 (0<L/d≦14), it is possible to decrease the noise of the passing refrigerant occurring due to transmission of vibration.
As the t/D becomes greater than 0.2, the result of measurement shifts toward the decrease in noise level difference. When the t/D is equal to or greater than 0.2, the difference in noise level becomes 3 dB or less in a case where 0<L/d≦14.
The sound pressure level of 1 dB or less is a level that the human being can hardly recognize. As shown in FIG. 4, the difference in noise level becomes about 1 dB when the L/d is 9. Therefore, the L/d may be more preferable 9 or less (L/d≦9).
(2) This embodiment can restrain the vibration of the nozzle portion 2 near the nozzle outlet 2 b, thus lessening an amount of displacement of the nozzle outlet 2 b of the nozzle portion 2 in operation of the refrigerant cycle device. This can reduce the influence of the repeated stress onto the nozzle material so as to improve the durability of the nozzle portion 2.
(3) In this embodiment, the nozzle support position is located at the first part 2 d on the upstream side of the refrigerant driving flow away from the second part 2 c opposed to the refrigerant suction port 3 a of the nozzle portion 2. Thus, the nozzle support position is located closer to the nozzle outlet 2 b, and the refrigerant suction port 3 a is located in the vicinity of the nozzle outlet 2 b.
Accordingly, it is possible to reduce a refrigerant flow path passing through the surrounding part of the nozzle portion 2 with the small sectional area, that is, a flow path of the refrigerant suction flow from the refrigerant suction port 3 a to the mixing portion 3 c, thereby decreasing loss in pressure of the refrigerant suction flow, and leading to a reduction in pressure loss of the refrigerant inside the ejector. As a result, the amount of increase in the refrigerant pressure of the ejector can be large, thereby enhancing the ejector effect in the refrigerant cycle device.
(4) In the ejector 1 of this embodiment, the ratio t/D of the body thickness t of the mixing portion 3 c to the inner diameter D of the mixing portion 3 c is 1.0 or more. Thus, the part near the nozzle outlet 2 b of the body portion 3 is relatively thick.
This can restrain the vibration of the body portion 3 occurring due to an excessive loss of vortex near the nozzle outlet 2 b, thereby further decreasing the noise of the passing refrigerant.
FIG. 5 shows a relationship between a difference in noise level (noise level difference) of the ejector between the presence and absence of the refrigerant suction flow, and the ratio t/D of the body thickness t to the diameter D of the mixing portion 3. FIG. 5 shows the result of measurement in a case where the L/d is 14.
As shown in FIG. 4, when the L/d is 14 and t/D is 0.2, the difference in noise level is about 3 dB. FIG. 5 shows that as the t/D becomes larger than 0.2, the difference in noise level becomes smaller. Setting the t/D to 1 or more can set the difference in noise level to 1 dB or less.
Setting the t/D to 1 or more means that the thickness t is equal to or larger than the inner diameter D. The upper limit of the t/D is determined by constraints of mounting places of the ejector, and can be arbitrarily set within an allowable range.
Thus, a margin for external corrosion due to an influence from an external environment and for internal corrosion due to an influence from an internal flowing material is increased, thereby enabling the improvement in durability in the ejector 1.
In this embodiment, the thickness of the mixing portion 3 c is increased, so that the body portion 3 can be constructed of a single component. This is because thickening the mixing portion 3 c can uniformize the outer diameter of the body portion 3 from the suction portion 3 b to the mixing portion 3 c, thereby making the contour of the body portion 3 in a simple shape without stepped portions on the external wall in the axial direction.
Since the contour (outer wall surface) of the body portion 3 is formed in a simple shape in this embodiment, attachment to the outer periphery of the ejector 1 can be performed easily by packing or the like.

Second Embodiment

A second embodiment of the present invention will be now described with reference to FIGS. 6 to 11. In an ejector 1 of the second embodiment, a part of the nozzle portion 2 downstream from the second part 2 c in a refrigerant driving flow is also supported. FIGS. 6 and 7 show a first example of the second embodiment.
In the ejector 1 shown in FIG. 6, a third part 2 f positioned on the downstream side of the driving flow of the nozzle portion 2 than the second part 2 c opposed to the refrigerant suction port 3 a is provided with protrusions 2 g. The protrusions 2 g are disposed on the outer wall of the third part 2 f of the nozzle portion 2 and protrude radially outside toward the inner wall of the body portion 3. The protrusions 2 g are located to abut against the inner wall of the body portion 3, and thus the nozzle portion 2 is also supported by the body portion 3 at the third part 2 f.
The third part 2 f on the downstream side of the driving flow of the nozzle portion 2 away from the second part 2 c opposed to the refrigerant suction port 3 a is, in other words, a part located between the refrigerant suction port 3 a in the axial direction of the nozzle portion 2 (in the longitudinal direction of the nozzle portion 2) and the nozzle outlet 2 b.
The protrusions 2 g are disposed partly, and not over the entire circumferential area of the third part 2 f of the nozzle portion 2, so as not to cover the flow path of the refrigerant suction flow in the circumferential direction of the nozzle portion 2 when viewing the section of the nozzle portion 2 with respect to the refrigerant flow in the nozzle portion 2. For example, as shown in FIG. 7, four protrusions 2 g are disposed at equal intervals in the outer circumferential direction of the nozzle portion 2 at the third part 2 f. In this example, the third part 2 f of the nozzle portion 2 is fixed to the body portion 3 at four points. However, the third part 2 f of the nozzle portion 2 may be fixed to the body portion 3 at plural point other than four.
The nozzle portion 2 of this embodiment has a thick base 21, and a cylindrical part 22 which has a thickness thinner than the base 21. The cylindrical part 22 extends from the base 21 in the axial direction. The cylindrical part 22 defines therein a high-pressure refrigerant flow path 2 a. The part 22 further defines an outlet 2 b of the high-pressure refrigerant flow path 2 a at its tip end. The cylindrical part 22 includes an axis portion 23 having a substantially constant outer diameter, and a conical portion 24 having an outer diameter gradually decreased in size from the axis portion 23 toward the outlet 2 b. The nozzle portion 2 is disposed in the cylindrical body portion 3. A low-pressure refrigerant flow path 25 enclosing the cylindrical part 22 is formed to be defined between the nozzle portion 2 and the body portion 3. The nozzle portion 2 has both ends in the axial direction via the suction portion 3 a connected and fixed to the body portion 3. The nozzle portion 2 and the body portion 3 are connected and fixed to each other by the base 21 on the upstream side of the refrigerant flow in the nozzle portion 2 from the refrigerant suction port 3 a. Furthermore, the nozzle portion 2 and the body portion 3 are connected and fixed to each other by the protrusions 2 g (support members) on the downstream side of the refrigerant flow in the nozzle portion 2 from the refrigerant suction port 3 a. The protrusion 2 g as the support member may be a stick-like or plate-like member extending in the radial direction. The nozzle portion 2 is supported and fixed by the plural protrusions 2 g disposed to be distributed at equal intervals in the circumferential direction. The protrusion 2 g as the support member is provided at a position away from the base 21 in the axial direction of the nozzle portion 2. Each of the protrusions 2 g as the support members is provided near the boundary between the axis portion 23 and the conical portion 24. As a result, the nozzle portion 2 protrudes from the protrusions 2 g as the support members toward downstream. The protrusions 2 g as the support members support the part located slightly closer to the tip end rather than the center in the entire length of the cylindrical part 22.
At this time, the end on the nozzle outlet 2 b side of the protrusion 2 g is a tip portion 2 e of the support portion of the nozzle portion 2. A length L from the tip portion 2 e of the support portion to the nozzle outlet 2 b is set such that the ratio L/d of the length L to a nozzle outlet diameter d is 14 or less.
Therefore, also in this embodiment, the nozzle support position can be located near the nozzle outlet 2 b, thereby restraining the vibration of the nozzle portion 2 near the nozzle outlet 2 b where the refrigerant flow velocity is fastest, like the first embodiment.
It is noted that the number of the protrusions 2 g is not limited to four, but may be any number that is more than one and which can be arbitrarily changed as long as the nozzle portion 2 is fixed to the body portion 3. Also, the shape of the protrusions 2 g can be arbitrarily changed.
Now, modified examples of the embodiments will be described below in detail.
FIG. 8 is a sectional view of the ejector 1 in a second example of the second embodiment, and FIG. 9 is a sectional view taken along a line IX-IX of FIG. 8. In the first example, the protrusions 2 g are provided in the nozzle portion 2, however, in the second example, protrusions 3 e may be provided not in the nozzle portion 2, but in the body portion 3 as shown in FIGS. 8 and 9. That is, protrusions 3 e which protrude radially inside toward the nozzle portion 2 are provided on the inner wall on the downstream side of the refrigerant flow of the body portion 3 away from the refrigerant suction port 3 a in the structure of the ejector 1. The protrusions 3 e may be brought into contact with the outer wall of the nozzle portion 2, thereby supporting the nozzle portion 2 by the body portion 3.
It is noted that although in the first and second examples the protrusions are provided only in one of the nozzle portion 2 and the body portion 3, the protrusions 2 g and 3 e may be provided in both of the nozzle portion 2 and the body portion 3.
FIG. 10 is a sectional view of an ejector 1 in a third example of the second embodiment, and FIG. 11 is a sectional view taken along the line XI-XI of FIG. 10. Although in the first and second examples, the fixing part (support part) between the nozzle portion 2 and the body portion 3 is provided in either the nozzle portion 2 or the body portion 3, a fixing part may be constructed of a component different from the nozzle portion 2 and the body portion 3 as shown in FIGS. 10 and 11.
That is, in the ejector 1 shown in FIGS. 10 and 11, a retaining ring 4 is disposed between the inner peripheral surface of the body portion 3 and the outer peripheral surface of the nozzle portion 2, at a position downstream from the second part 2 c of the nozzle portion 2. The retaining ring 4 has such a shape as not to cover the flow path of the refrigerant suction flow. For example, the retaining ring 4 includes a plurality of fixing portions 4 a for fixing the nozzle portion 2 to the body portion 3, and connection portions 4 b for connecting the adjacent fixing portions 4 a and forming a flow path between the nozzle portion 2 and the connection portion itself. The retaining ring 4 is made of, for example, organic material, such as resin or rubber, or the same metal material as that of the nozzle portion 2 or the body portion 3.
At this time, the fixing portions 4 a, like the protrusions 2 g and 3 e as explained in the first and second examples, are partly disposed in the circumferential direction of the nozzle portion. The shape of the retaining ring 4 is not limited to the shape shown in FIGS. 10 and 11, and may be any shape that is changed so as to fix the nozzle portion 2 to the body portion 3 not to cover all the flow path of the refrigerant suction flow.

Third Embodiment

In a third embodiment, the part on the upstream side of the refrigerant driving flow in the nozzle portion 2 from the second part 2 c opposed to the refrigerant suction port 3 a is supported by the body portion 3. In addition, the part on the downstream side of the refrigerant driving flow in the nozzle portion 2 from the second part 2 c is also located to be supported by the body portion 3.
As shown in FIG. 12, the ejector 1 of this embodiment includes a driving portion 5 for driving the nozzle portion 2 in the axial direction as indicated by the arrow in the figure to allow the nozzle portion 2 to be displaced with respect to the body portion 3. The driving portion 5 is controlled by control means (not shown).
As the driving portion 5 can be employed, for example, a stepping motor, a floating structure using a fluid force, a mechanical driving means, such as a check valve structure or the like, or an electric driving means, such as a proportional solenoid or the like.
The shapes of the nozzle portion 2 and the body portion 3 of this embodiment are basically the same as those in the first and second embodiments. The outer diameter of the nozzle portion 2 is larger than the inner diameter of the mixing portion 3 c of the body portion 3. When the nozzle portion 2 is moved to the mixing portion 3 c, the outer wall of the nozzle portion 2 is in contact with the inner wall of the body portion 3.
More specifically, the outer shape of the tip side portion of the nozzle portion 2 is formed in a tapered shape to form a tapered part 2 h such that the outer diameter of the tapered part 2 h of the nozzle portion 2 is gradually decreased in size toward the nozzle outlet 2 b. The inside shape of the body portion 3 is formed in such a tapered shape that the inner diameter of the suction portion 3 b is gradually decreased in size toward the mixing portion 3 c. When the nozzle portion 2 is inserted into the mixing portion 3 c, the tapered part 2 h of the nozzle portion 2 is brought into contact with the inner wall constituting the suction portion 3 b.
In this embodiment, the driving portion 5 can be controlled by the control means to displace the position of the nozzle portion 2 as shown in FIGS. 13 and 14.
As shown in FIG. 13, the refrigerant cycle device in an operational condition in presence of the refrigerant suction flow inside the ejector 1 is in a first state where the outer wall of the tapered part 2 h of the nozzle portion 2 is spaced apart from the inner wall of the suction portion 3 b of the body portion 3 to form the flow path of the refrigerant sucked from the refrigerant suction port 3 a.
As shown in FIG. 14, the refrigerant cycle device in an operational condition in the absence of the refrigerant suction flow inside the ejector 1 is in a second state where the nozzle portion 2 is displaced from the state shown in FIG. 13 so as to stick into the mixing portion 3 b, thereby causing the nozzle portion 2 to be abutted against the body portion 3. In the second state, the tapered part 2 h of the nozzle portion 2 is brought into contact with the inner wall of the body portion 3 constituting the suction portion 3 b thereby to close the flow path of the refrigerant sucked from the refrigerant suction port 3 a.
At this time, the area where the tapered part 2 h of the nozzle portion 2 is in contact with the suction portion 3 b of the body portion 3 is also used as the nozzle support position. The ratio L/d of the length L from the tip portion 2 e of the support portion to the nozzle outlet 2 b to the diameter d of the nozzle outlet is 14 or less.
In the third embodiment, in the absence of the refrigerant suction flow inside the ejector 1, the nozzle portion 2 is abutted against the body portion 3, thereby the tapered part 2 h of the nozzle portion 2 is supported by the suction portion 3 b of the body portion 3.
Thus, also in the third embodiment, the nozzle support position can be located near the nozzle outlet 2 b, thereby preventing the vibration of the nozzle portion 2 near the nozzle outlet 2 b where the refrigerant flow velocity is fastest, like the first and second embodiments.
In the third embodiment, the nozzle portion 2 is abutted against the body portion 3 in the absence of the refrigerant suction flow inside the ejector 1 to close the flow path of the refrigerant sucked from the refrigerant suction port 3 a. Accordingly, it is possible to restrain the occurrence of the vortex of the driving flow, even when refrigerant is not drawn from the second evaporator 18 to the refrigerant suction port 3 a
Therefore, the effect of restraining the refrigerant passing noise occurring due to the increased loss in vortex at the nozzle outlet 2 b can be more improved.
Since the nozzle portion 2 is abutted against the body portion 3 so as to close the flow path of the refrigerant sucked from the refrigerant suction port 3 a in the ejector 1 of this embodiment, the ejector 1 can also be used as an electromagnetic valve for intermittently allowing the refrigerant suction flow to pass through. In this case, for example, the electromagnetic valve 20 can be omitted from the refrigerant cycle device shown in FIG. 1.

Fourth Embodiment

A fourth embodiment of the present invention will described with reference to FIGS. 15 and 16. As shown in FIGS. 15 and 16, an ejector 1 of this embodiment is provided with an anti-vibration member 6 (vibration prevention member, cover member) for preventing the vibration of the body portion 3 with respect to the ejector 1 shown in FIG. 2A.
The anti-vibration member 6 is located to prevent the vibration from being transmitted to the outside, or to lessen the vibration. The anti-vibration member 6 is constructed of an elastic body which is made of rubber or the like, typified by butyl rubber, for example. The anti-vibration member 6 is disposed to cover the entire outer periphery of the body portion 3. This can restrain the vibration of the body portion 3 near the nozzle outlet 2 b due to the increase in loss of the vertex.
The anti-vibration member 6 may not necessarily cover the entire area of the outer periphery of the body portion 3, and has only to cover the downstream side part of the refrigerant flow from the nozzle outlet 2 b, located near the nozzle outlet 2 b on the outer periphery of the body portion 3.
Instead of the anti-vibration member 6, a soundproof member made of porous material or the like may be provided on the outer periphery of the body portion 3.

Other Embodiments

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.
For example, the above first embodiment has explained the example in which the nozzle portion 2 and the body portion 3 of the ejector 1 are individual structures, but the nozzle portion 2 and the body portion 3 may be an integrated structure constructed of one component, as shown in FIG. 17. The structures of other components of the ejector 1 are the same as those of the first embodiment.
The ejector 1 shown in FIG. 17 may be made of, for example, aluminum, and manufactured using a mold.
Also in the ejector 1 shown in FIGS. 6 to 11 as described in the second embodiment, the nozzle portion 2 and the body portion 3 can be constructed of an integrated structure as mentioned above. The integrated structure of the nozzle portion 2 and the body portion 3 can securely fix the nozzle portion 2 to the body portion 3, as compared to the individual structures of the nozzle portion 2 and the body portion 3, thereby further restraining the vibration of the nozzle portion 2.
The above-described embodiments have described the example which satisfies the following both conditions: 0<L/d≦14, and t/D≧1. Even if the condition of t/D≧1 is not satisfied, because the L/d is more predominant for the sound than the t/D, at least the condition of 0<L/d≦14 has only to be satisfied. That is, at least the condition of 0<L/d≦14 is satisfied, the other condition such as the t/D may be suitably changed without being limited.
Furthermore, the structure of the nozzle portion 2 is not limited to the structure shown in each figure or/and described in the above embodiments, but various structures, such as a Laval nozzle or a tapered nozzle, can be employed.
In the above-described embodiments, the ejector 1 is used for the refrigerant cycle device shown in FIG. 1. However, the ejector 1 can be used for other refrigerant cycle device. For example, the ejector 1 may be used for a refrigerant cycle device having a vapor-liquid separator and a refrigerant passage through which liquid refrigerant of the vapor-liquid separator is introduced to the refrigerant suction port 3 a via an evaporator, without using the branch passage 16.
That is, the ejector 1 can be used for a refrigerant cycle device which includes a compressor for sucking and compressing refrigerant, a radiator for radiating high-pressure refrigerant discharged from the compressor, the ejector 1 having the nozzle portion 2 for decompressing the refrigerant from the radiator, and an evaporator for evaporating refrigerant to be drawn into the refrigerant suction port 3 a by the jet flow of the refrigerant jetted from the nozzle outlet 2 b. The refrigerant cycle device may be operated with both the refrigerant driving flow and the refrigerant suction flow in the ejector 1, or may be operated with only the refrigerant driving flow in the ejector 1.
Furthermore, the above embodiments can be suitably combined in the structure of the ejector 1.
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 for a refrigerant cycle device, the ejector comprising:

a nozzle portion for decompressing and expanding refrigerant flowing therein; and

a body portion which accommodates the nozzle portion to support the nozzle portion at a support portion, the body portion having a refrigerant suction port from which refrigerant is drawn by a high-speed refrigerant flow jetted from a nozzle outlet of the nozzle portion, wherein:

the nozzle portion is located in the body portion to have an ejector refrigerant passage through which the refrigerant jetted from the nozzle outlet of the nozzle portion and the refrigerant drawn from the refrigerant suction port flow; and

the nozzle portion is supported in the body portion to have the following relationship of 0<L/d≦14, in which L/d is a ratio of a length (L) between a downstream tip portion of the support portion and the nozzle outlet to a diameter (d) of the nozzle outlet.

2. The ejector according to claim 1, wherein:

the body portion has a mixing portion in which the refrigerant jetted from the nozzle outlet and the refrigerant drawn from the refrigerant suction port are mixed; and

the mixing portion has a wall thickness (t) and an inner diameter (D), and a ratio (t/D) of the wall thickness (t) to the inner diameter (D) is equal to or larger than 0.2.

3. The ejector according to claim 1, wherein:

the nozzle portion has a first part, a second part downstream from the first part in a refrigerant flow of the nozzle portion and positioned to correspond to an area of the refrigerant suction port, and a third part downstream from the second part in the refrigerant flow of the nozzle portion; and

the first part of the nozzle portion is supported by the body portion at the support portion.

4. The ejector according to claim 1, wherein:

the third part of the nozzle portion is supported by the body portion at the support portion.

5. The ejector according to claim 4, wherein:

the nozzle portion has a protrusion portion protruding from an outer wall surface of the third part of the nozzle portion toward the body portion; and

the protrusion portion of the nozzle portion contacts an inner wall of the body portion to form the support portion.

6. The ejector according to claim 4, wherein:

the body portion has a protrusion portion protruding from an inner wall of the body portion to the nozzle portion at a position corresponding to the third part of the nozzle portion; and

the protrusion portion of the body portion contacts an outer wall of the nozzle portion to form the support portion.

7. The ejector according to claim 4, further comprising a support member located between an inner wall of the body portion and an outer wall of the third part of the nozzle portion; and

the nozzle portion is supported in the body portion by the support member.

8. The ejector according to claim 1, further comprising

a driving portion for driving the nozzle portion so as to move the nozzle portion in an axial direction relative to the body portion, wherein

the nozzle portion is movable by the driving portion between a first state where an outer wall of the nozzle portion is spaced from an inner wall of the body portion such that the refrigerant drawn from the refrigerant suction port flows, and a second state where the outer wall of the nozzle portion contacts the inner wall of the body portion to be supported by the body portion at the support portion such that a refrigerant flow from the refrigerant suction port is closed.

9. An ejector for a refrigerant cycle device, the ejector comprising:

a nozzle portion having therein a nozzle passage in which high-pressure refrigerant before being decompressed flows, the nozzle portion having an approximately cylindrical outer wall portion and a nozzle outlet from which the refrigerant decompressed in the nozzle passage is jetted;

a body portion which accommodates the nozzle portion to define a suction passage, between the nozzle portion and the body portion, extending from the cylindrical outer wall portion to the nozzle outlet, the body portion having a refrigerant suction port that is opened radially outwardly of the cylindrical outer wall portion to communicate with the suction passage;

a first fixing member for connecting and fixing the nozzle portion to the body portion at a position upstream from the refrigerant suction port in a refrigerant flow of the nozzle passage; and

a second fixing member for connecting and fixing the nozzle portion to the body portion at a position downstream from the refrigerant suction port in the refrigerant flow of the nozzle passage.

10. The ejector according to claim 1, wherein:

the nozzle portion and the body portion are made of different members; and

the nozzle portion is fixed to the body portion by fastening or pressing means to be supported by the body portion.

11. The ejector according to claim 1, wherein:

the mixing portion has approximately a uniform wall thickness (t) and a uniform inner diameter (D), and a ratio t/D of the wall thickness (t) to the inner diameter (D) is equal to or larger than 1.

12. The ejector according to claim 1, further comprising

a cover member, which is located to cover an outer surface of the body portion at least in an area near the nozzle outlet,

wherein the cover member is made of a material to reduce at least one of vibration and noise caused in the body portion.

13. The ejector according to claim 1, wherein:

the body portion has a mixing portion in which the refrigerant jetted from the nozzle outlet and the refrigerant drawn from the refrigerant suction port are mixed, and a diffuser in which a passage sectional area is increased from the mixing portion toward downstream side; and

the body portion has a uniform outer wall surface at least in the mixing portion and the diffuser.

14. The ejector according to claim 13, wherein:

the mixing portion has approximately a uniform wall thickness; and

the diffuser has a wall thickness that is gradually reduced from the mixing portion toward downstream.

15. The ejector according to claim 13, wherein the body portion has an approximately uniform cylindrical outer surface in an entire area.

16. A refrigerant cycle device comprising:

a compressor for sucking and compressing refrigerant;

a radiator for cooling high-pressure refrigerant discharged from the compressor;

the ejector according to claim 1, the nozzle portion of the ejector being located to decompress the refrigerant flowing from the radiator;

a first evaporator for evaporating the refrigerant flowing out of the ejector;

a branch passage branched from a refrigerant flow between the radiator and the nozzle portion of the ejector, and joined to the refrigerant suction port of the ejector;

a throttle unit located in the branch passage to decompress the refrigerant flowing into the branch passage;

a second evaporator located in the branch passage downstream from the throttle unit; and

a switching unit located in the branch passage to switch a refrigerant flow to the second evaporator.