WO2019181736A1

WO2019181736A1 - Ejector

Info

Publication number: WO2019181736A1
Application number: PCT/JP2019/010600
Authority: WO
Inventors: 田中　康太
Original assignee: 株式会社デンソー
Priority date: 2018-03-22
Filing date: 2019-03-14
Publication date: 2019-09-26

Abstract

This ejector is configured such that the wall surface on a needle side of a nozzle has an outlet (41z) positioned at the end on the leading end side in a fluid flow path and a throat (41x) that is positioned on the opposite side of the outlet on the leading end side and that projects toward the needle. When a needle lift amount (R) is within a first range, a throat flow path cross-sectional area is smaller than an outlet flow path cross-sectional area, and the throat flow path cross-sectional area is smallest among areas of gaps between the nozzle and the needle in all cross-sections orthogonal to an axial direction within the fluid flow path. When the needle lift amount is within a second range greater than the first range, the throat flow path cross-sectional area is larger than the outlet flow path cross-sectional area, and the outlet flow path cross-sectional area is smallest among the areas of the gaps between the nozzle and the needle in all the cross-sections orthogonal to the axial direction within the fluid flow path.

Description

Ejector

Cross-reference to related applications

This application is based on Japanese Patent Application No. 2018-54863 filed on Mar. 22, 2018 and Japanese Patent Application No. 2018-160630 filed on Aug. 29, 2018. The description is incorporated by reference.

This disclosure relates to ejectors.

Conventionally, there has been known an ejector that has a nozzle and a needle, and sucks a fluid outside the nozzle by an entraining action of a working fluid ejected from the tip of the nozzle through a fluid flow path inside the nozzle. For example, in Patent Document 1, the cross-sectional area of the portion surrounded by the inner surface of the nozzle is constant at the tip of the nozzle.

JP 2004-144043 A

According to the inventor's study, when the operating conditions of the ejector (for example, the needle lift amount) and the refrigerant to be used are determined, the optimum minimum area of the region between the nozzle and the needle in the nozzle and the optimum outlet channel cross-sectional area are determined. Is decided. However, when the ejector is used in a plurality of operating conditions, it is difficult to determine the minimum area of the ejector and the outlet channel cross-sectional area that are optimal for all of the operating conditions.
In particular, when the needle lift amount is large, the cross-sectional area of the outlet channel may become large, resulting in excessive expansion. As a countermeasure for this, there is a method of shortening the nozzle. However, if this is done, the nozzle efficiency will deteriorate. This is because, in order to increase the nozzle efficiency, it is generally desirable to gradually increase the flow path cross-sectional area from the root side to the outlet.

This disclosure has a first object of suppressing overexpansion of the ejector by a method different from shortening the nozzle.

Further, Patent Document 1 discloses an ejector in which a needle has a two-step taper. That is, the needle includes a first taper portion that tapers toward the tip end side, and a second taper portion that tapers further toward the tip end side from the first taper portion. And the taper angle of the 1st taper part and the taper angle of the 2nd taper part are discontinuous in the boundary part of the 1st taper part and the 2nd taper part.

According to the inventor's study, when the needle has a two-step taper, the flow passage cross-sectional area of the gap between the nozzle and the needle suddenly expands on the tip side of the boundary portion of the needle. Usually, it is desirable that a throat that minimizes the cross-sectional area of the flow path of the gap between the nozzle and the needle is formed on the wall surface on the needle side of the nozzle, and the working fluid boils at this throat. However, as a result of the inventors' investigation, the working fluid boils at the boundary portion separately from the throat portion. If the working fluid boils at a portion other than the intended throat, the energy recovery efficiency of the ejector will be reduced.

A second object of the present disclosure is to suppress a decrease in energy recovery efficiency that occurs due to boiling of the working fluid at a portion other than the intended portion in an ejector including a needle having a two-step taper. To do.

According to one aspect of the present disclosure, an ejector is disposed in a nozzle and a fluid flow path inside the nozzle, and moves in an axial direction with respect to the nozzle and tapers toward a tip end side of the ejector. The fluid outside the nozzle is sucked by the entraining action of the working fluid ejected from the tip end side of the ejector in the nozzle through the fluid flow path inside the nozzle, and the needle of the nozzle The side wall surface has an outlet located at an end of the fluid flow path on the tip side, and a throat portion that is located on the opposite side of the tip from the tip and protrudes toward the needle. The cross-sectional area of the throat channel is the area of the gap between the nozzle and the needle in the cross-section passing through the throat and perpendicular to the axial direction. When the needle lift amount indicating the degree of separation of the needle from the nozzle in the axial direction is in the first range, the area of the gap between the nozzle and the needle in a cross section orthogonal to the axial direction through The throat flow path cross-sectional area is smaller than the outlet flow path cross-sectional area, and out of the area of the gap between the nozzle and the needle in all cross sections orthogonal to the axial direction in the fluid flow path When the throat channel cross-sectional area is the smallest and the needle lift amount is in the second range larger than the first range, the throat channel cross-sectional area is larger than the outlet channel cross-sectional area, In addition, among the areas of the gaps between the nozzle and the needle in all cross sections orthogonal to the axial direction in the fluid flow path, the cross-sectional area of the outlet flow path is the smallest. That.

Thus, when the needle lift amount is in the first range, the throat channel cross-sectional area is smaller than the outlet channel cross-sectional area. Of the flow path cross-sectional area of the gap between the nozzle and the needle, the throat flow path cross-sectional area is minimized. That is, the nozzle and the needle operate as a Laval nozzle.

Also, when the needle lift amount is in the second range that is larger than the first range, the throat channel cross-sectional area is larger than the outlet channel cross-sectional area. Of the channel cross-sectional area of the gap between the nozzle and the needle, the outlet channel cross-sectional area is minimized. That is, the nozzle and the needle operate as a Laval nozzle. Thus, even when the amount of needle lift is large, overexpansion can be suppressed by operating the nozzle and needle as a plug nozzle.

According to another aspect of the present disclosure, the ejector includes a nozzle and a needle disposed in a fluid flow path inside the nozzle, and the ejector in the nozzle passes through the fluid flow path inside the nozzle. The fluid outside the nozzle is sucked by the entrainment action of the working fluid ejected from the tip end side of the ejector, and the needle tapers toward the tip end side, and the first taper portion A taper of the first taper portion at a boundary between the first taper portion and the second taper portion, and a second taper portion connected to the tip end side and further tapered toward the tip end side. The second taper angle, which is the taper angle of the second taper portion at the boundary portion, is larger than the first taper angle, which is a corner, and the nozzle-side wall surface of the nozzle has the nose. When the throat portion that minimizes the flow path cross-sectional area of the gap between the needle and the needle is formed and the entrainment effect is exhibited, the boundary portion is located on the tip side of the throat portion, and the entrainment effect When the is exhibited, the portion of the wall surface closer to the distal end than the throat portion is an ejector having a shape that narrows the region surrounded by the wall surface toward the distal end side.

Thus, when the entrainment effect is exerted, boiling at the boundary portion can be suppressed by narrowing the flow path surrounded by the wall surface of the nozzle toward the front end side from the boundary portion of the nozzle. . As a result, it is possible to suppress a decrease in energy recovery efficiency that occurs due to boiling of the working fluid at a portion other than the intended portion and a boiling delay.

Note that reference numerals with parentheses attached to each component and the like indicate an example of a correspondence relationship between the component and the like and specific components described in the embodiments described later.

It is a schematic diagram of the ejector cycle which concerns on 1st Embodiment. It is a schematic diagram of an ejector. It is an enlarged view of an ejector. It is an enlarged view of the front-end | tip part of a nozzle and the front-end | tip part of a needle. It is a figure which shows the change of a flow-path cross-sectional area. It is an enlarged view of the ejector which concerns on 2nd Embodiment. It is an enlarged view of the ejector which concerns on 3rd Embodiment. It is a schematic diagram of the ejector cycle which concerns on 4th Embodiment. It is an enlarged view of the front-end | tip part of a nozzle and the front-end | tip part of a needle. It is a figure which shows the change of a flow-path cross-sectional area in case a nozzle operate | moves as a Laval nozzle. It is a figure which shows the change of flow-path cross-sectional area in case a nozzle operate | moves as a plug nozzle. It is a graph which shows the area | region where a nozzle operate | moves as a Laval nozzle, and the area | region which operate | moves as a plug nozzle. It is a figure which shows the relationship between the needle lift amount at the time of using the conventional straight-shaped nozzle, and an exit flow-path cross-sectional area. It is an enlarged view of the ejector which concerns on 5th Embodiment. It is an enlarged view of the ejector which concerns on 6th Embodiment.

(First embodiment)
The first embodiment will be described below. The ejector according to the present embodiment is used in an ejector cycle for a vehicle air conditioner. 1 is a schematic diagram of an ejector cycle using carbon dioxide as a refrigerant, FIG. 2 is a schematic diagram of an ejector 40, and FIG. 3 is an enlarged view of a nozzle 41. The refrigerant corresponds to the working fluid.

In FIG. 1, a compressor 10 is a well-known variable capacity compressor that obtains power from a traveling engine and sucks and compresses a refrigerant. The discharge capacity of the compressor 10 is the temperature or pressure in an evaporator 30 to be described later. Is controlled to be within a predetermined range. In addition, you may employ | adopt as the compressor 10 what can control discharge refrigerant | coolant flow volume by rotation speed like an electric compressor.

The heat radiator 20 is a high-pressure heat exchanger that cools the refrigerant by exchanging heat between the refrigerant discharged from the compressor 10 and outdoor air. The evaporator 30 is a low-pressure side heat exchanger that cools the air blown into the room by evaporating the liquid by evaporating the liquid phase refrigerant by exchanging heat between the air blown into the room and the liquid phase refrigerant.

In the present embodiment, the refrigerant is carbon dioxide, and the discharge pressure of the compressor 10 is equal to or higher than the critical pressure of the refrigerant. The refrigerant does not condense in the radiator 20 and its enthalpy is lowered by lowering the temperature. However, if the refrigerant is not carbon dioxide but HFC134a, for example, when the discharge pressure of the compressor 10 is less than the critical pressure, the enthalpy is reduced while the refrigerant is condensed in the radiator 20.

The ejector 40 expands the refrigerant under reduced pressure and sucks the gas-phase refrigerant evaporated in the evaporator 30 and converts the expansion energy into pressure energy to increase the suction pressure of the compressor 10, which will be described in detail later. .

The gas-liquid separator 50 is a gas-liquid separator that stores the refrigerant by flowing the refrigerant flowing out from the ejector 40 into the vapor-phase refrigerant and the liquid-phase refrigerant. The gas-phase refrigerant outlet of the gas-liquid separator 50 is connected to the suction side of the compressor 10. The liquid-phase refrigerant outlet of the gas-liquid separator 50 is connected to the inflow side on the evaporator 30 side. The throttle 60 is a decompression unit that decompresses the liquid-phase refrigerant that has flowed out of the gas-liquid separator 50.

The blower 21 blows cooling air, that is, outside air, to the radiator 20. The blower 31 blows air blown into the evaporator 30 into the room.

Next, the ejector 40 will be described. Hereinafter, the tip side of the ejector 40 is simply referred to as the tip side. The ejector 40 is a momentum transport type pump. As shown in FIG. 2, the ejector 40 includes a nozzle 41, a mixing unit 42, a diffuser 43, a needle 44, a housing 45, a block 46, and the like. The nozzle 41 is a plug nozzle that converts the pressure energy of the flowing high-pressure refrigerant into velocity energy and decompresses and expands the refrigerant in an isentropic manner. The mixing unit 42 mixes the refrigerant flow injected from the nozzle 41 and the gas-phase refrigerant while sucking the vapor-phase refrigerant evaporated in the evaporator 30 by the high-speed refrigerant flow injected from the nozzle 41. The diffuser 43 converts the velocity energy into pressure energy and increases the pressure of the refrigerant while mixing the refrigerant injected from the nozzle 41 and the refrigerant sucked from the evaporator 30.

The needle 44 is formed in a conical taper shape so that the cross-sectional area decreases toward the tip side of the ejector 40. Here, the cross-sectional area refers to a cross-sectional area when cut by a plane perpendicular to the axis of the needle 44. The nozzle 41 and the needle 44 may be made of metal such as stainless steel. The needle 44 is driven by an actuator (not shown) according to the flow rate of the high-pressure refrigerant flowing into the nozzle 41 and can be displaced in the axial direction of the needle 44. The needle 44 is disposed coaxially with the nozzle 41 in the space inside the nozzle 41.

The housing 45 is a cylindrical member that forms the mixing portion 42 and the diffuser 43, and the outlet 45 a of the diffuser 43 is connected to the inlet 76 side of the gas-liquid separator 50. The block 46 is a metal member that houses the nozzle 41 and is provided with a high-pressure refrigerant inlet 46a connected to the radiator 20 side and a low-pressure refrigerant inlet 46b connected to the evaporator 30 side. The housing 45 and the block 46 are joined by welding or brazing. As the material of the housing 45 and the block 46, aluminum, stainless steel, brass or the like can be considered.

Then, the needle 44 and the nozzle 41 which are press-fitted and fixed on the same axis are press-fitted and fixed to the block 46, whereby the needle 44 and the nozzle 41 are assembled inside the block 46. A hole for press-fitting the nozzle 41 is closed by a lid 46c.

In the mixing unit 42, mixing is performed so that the sum of the momentum of the refrigerant flow ejected from the nozzle 41 and the momentum of the refrigerant flow sucked into the ejector 40 from the evaporator 30 is preserved. Increased static pressure.

On the other hand, in the diffuser 43, the dynamic pressure of the refrigerant is converted into a static pressure by gradually increasing the cross-sectional area of the flow path. Therefore, in the ejector 40, the refrigerant pressure rises in both the mixing unit 42 and the diffuser 43.

In the ejector 40, it is desirable that the refrigerant pressure increases so that the sum of momentums of the two refrigerant flows is preserved in the mixing unit 42, and the refrigerant pressure increases so that energy is preserved in the diffuser 43.

Here, the configuration of the needle 44 and the nozzle 41 will be described in more detail. As shown in FIGS. 3 and 4, the needle 44 has a body portion 440, a first taper portion 441, and a second taper portion 442. The trunk portion 440, the first taper portion 441, and the second taper portion 442 are integrally and coaxially formed as a whole. The body portion 440 has a substantially cylindrical shape, and is connected to the first taper portion 441 on the distal end side.

The first taper portion 441 has a substantially truncated cone shape that is tapered toward the tip side. In the present embodiment, the first taper angle θE1 that is the Dapper angle of the first taper portion 441 is constant. Therefore, the first taper angle θE1 is constant from the end on the body 440 side to the end on the front end side of the first taper portion 441.

The second taper portion 442 has a substantially conical shape that is connected to the end of the first taper portion 441 on the front end side and is further tapered toward the front end side. In the present embodiment, the second taper angle θE2 that is the Dapper angle of the second taper portion 442 is constant. Therefore, the second taper angle θE2 is constant from the end on the first taper portion 441 side to the end on the tip end side in the second taper portion 442.

Therefore, the second taper angle θE2 at the boundary portion 44x is larger than the first taper angle θE1 at the boundary portion 44x (that is, the bendable portion) between the first taper portion 441 and the second taper portion 442. Further, the first taper angle θE1 and the second taper angle θE2 are discontinuous at the boundary portion 44x. That is, the taper angle of the needle 44 changes suddenly and discontinuously from the first taper portion 441 side to the second taper portion 442 side of the boundary portion 44x.

Further, the wall surface, that is, the inner wall surface of the nozzle 41 on the needle 44 side has a root surface 410, a first diaphragm surface 411, and a second diaphragm surface 412. The root surface 410, the first diaphragm surface 411, and the second diaphragm surface 412 are disposed coaxially with the body portion 440, the first taper portion 441, and the second taper portion 442. The root surface 410 has a substantially cylindrical shape and surrounds the trunk portion 440.

The first diaphragm surface 411 is connected to the tip side end of the root surface 410 and further tapers toward the tip side at a first taper angle θZ1. The shape of the first diaphragm surface 411 is substantially the same as the side surface of the truncated cone. Accordingly, the first diaphragm surface 411 is reduced in diameter toward the distal end side. For this reason, the region surrounded by the first diaphragm surface 411 becomes narrower toward the tip side. Here, the diameter of the first diaphragm surface 411 refers to the diameter of the first diaphragm surface 411 in a cross section orthogonal to the axis of the nozzle 41.

Also, the first taper angle θZ1, which is the taper angle of the first diaphragm surface 411, is larger than the first taper angle θE1 described above. Therefore, the flow path cross-sectional area of the gap between the first throttle surface 411 and the first taper portion 441 also decreases toward the tip side.

The second aperture surface 412 is connected to the end of the first aperture surface 411 on the tip side and is further tapered toward the tip side at a second taper angle θZ2. The shape of the second diaphragm surface 412 is substantially the same as the side surface of the cone. Accordingly, the second aperture surface 412 is reduced in diameter toward the tip side. For this reason, the region surrounded by the second diaphragm surface 412 becomes narrower toward the tip side. Here, the diameter of the second diaphragm surface 412 refers to the diameter of the second diaphragm surface 412 in a cross section orthogonal to the axis of the nozzle 41.

Further, the second taper angle θZ2 that is the taper angle of the second diaphragm surface 412 is smaller than the first taper angle θE1 described above. Therefore, the flow path cross-sectional area of the gap between the second throttle surface 412 and the first taper portion 441 may increase as it goes toward the tip side. Further, the first taper angle θZ1 and the second taper angle θZ2 are discontinuous at the throat portion 41x corresponding to the boundary between the first diaphragm surface 411 and the second diaphragm surface 412.

Further, the second taper angle θZ2 of the second diaphragm surface 412 is smaller than the above-described second taper angle θE2. Therefore, the flow path cross-sectional area of the gap between the second throttle surface 412 and the second taper portion 442 is increased toward the tip side.

Therefore, the channel cross-sectional area of the gap between the nozzle 41 and the needle 44 varies depending on the position along the axis CL (hereinafter referred to as the axial position), as indicated by the solid line 71 in FIG. Here, the axis CL is the axis of the needle 44 and the axis of the nozzle 41. The flow path cross-sectional area at a certain axial position refers to the area of the gap between the nozzle 41 and the needle 44 in a cross section that passes through the axial position and is orthogonal to the direction of the axis CL. However, if the needle 44 is not present in the cross section, the area of the portion surrounded by the nozzle 41 in the cross section becomes the flow path cross sectional area.

As shown by the solid line 71, at the axial position corresponding to the first throttle surface 411, the flow path cross-sectional area continues to decrease at a constant reduction rate toward the axial position P1 corresponding to the throat 41x. Then, at the axial position P1, the channel cross-sectional area turns from decreasing to increasing. That is, the channel cross-sectional area is minimal and minimal at the axial position P1. The flow path cross-sectional area continues to increase at a constant increase rate from the axial position P1 to the axial position P2 corresponding to the boundary portion 44x. Furthermore, at the axial direction position P2, the increasing rate of the channel cross-sectional area increases discontinuously. Then, from the axial position P2 to the axial position P3 corresponding to the tip of the nozzle 41, the flow path cross-sectional area continues to increase while maintaining the increased rate after the increase. Thus, the throat portion 41x along the direction of the axis CL minimizes and minimizes the flow path cross-sectional area. The rate of increase refers to the amount of increase in the cross-sectional area of the channel when the axial position is changed by a unit distance toward the tip side.

In the examples of FIGS. 4 and 5, the boundary portion 44x is positioned closer to the distal end side in the axis CL direction than the throat portion 41x. This positional relationship is realized in most cases when the ejector 40 is used. The tip of the needle 44 may be further on the tip side of the ejector 40 than the tip of the nozzle 41, or may be on the side opposite to the tip side.

Here, the relationship among the first taper angle θE1, the second taper angle θE2, the first taper angle θZ1, and the second taper angle θZ2 is summarized as follows: θZ2 <θE1 <θE2. In general usage conditions, the nozzle 41 of the ejector 40 accelerates the refrigerant passing through the nozzle 41 to a speed higher than the speed of sound. In order to realize this, it is preferable that the flow path cross-sectional area of the refrigerant gradually decreases and gradually increases after passing through the throat portion 41x where the flow path cross-sectional area is minimized. In fact, in the present embodiment, the flow path cross-sectional area gradually decreases from the upstream to the downstream of the refrigerant flow, becomes minimum at the throat portion 41x, and the flow path cross-sectional area increases at the downstream portion from the throat portion 41x. In order to obtain the above-described structure, it is desirable that the above-described angular relationship be satisfied. In the present embodiment, the relationship θE1 <θZ1 is also realized.

Next, the general operation of the ejector cycle will be described. The refrigerant discharged from the compressor 10 is cooled on the radiator 20 side, and then flows into the fluid flow path inside the nozzle 41 from the high-pressure refrigerant inlet 46a of the ejector 40. The refrigerant that has flowed into the nozzle 41 is isentropically decompressed and expanded in the throat portion 41x to boil. At this time, the pressure energy of the refrigerant is converted into velocity energy, and the gas-liquid two-phase refrigerant is ejected from the tip of the nozzle 41 at a high speed equal to or higher than the speed of sound. Then, the gas-phase refrigerant evaporated in the evaporator 30 is sucked from the outside of the nozzle 41 to the mixing unit 42 through the space between the nozzle 41 and the block 46 by the entrainment effect of the injected refrigerant. Is done.

The refrigerant injected from the tip of the nozzle 41 and the refrigerant sucked from the low-pressure refrigerant inlet 46 b are mixed with each other in the mixing unit 42 after flowing into the mixing unit 42. The refrigerant mixed in the mixing unit 42 enters the diffuser 43. In the diffuser 43, the speed energy of the refrigerant is converted into pressure energy by increasing the refrigerant passage area, and the pressure of the refrigerant increases. The refrigerant that has passed through the diffuser 43 flows out from the outlet 45a and flows into the gas-liquid separator 50. Of the refrigerant flowing into the gas-liquid separator 50, the gas-phase refrigerant is sucked into the compressor 10 and compressed again. Further, the liquid phase refrigerant out of the refrigerant flowing into the gas-liquid separator 50 is decompressed again by the throttle 60 and then evaporated by the evaporator 30.

In this way, when the ejecting action of the ejector 40 is exerted, the nozzle 41 is often arranged as shown in FIGS. That is, the first taper portion 441 faces both the first diaphragm surface 411 and the second diaphragm surface 412, and part or all of the second taper portion 442 faces the second taper portion 442. And the axial direction position of the boundary part 44x exists in the front end side rather than the axial direction position of the throat part 41x.

In such a case, as shown in FIG. 5, the rate of increase in the cross-sectional area of the flow path increases discontinuously toward the front end side at the boundary portion 44 x, so that the refrigerant may also boil at the boundary portion 44 x. There is.

However, in the present embodiment, as already described, the region surrounded by the second diaphragm surface 412 becomes narrower toward the tip side. Here, unlike the present embodiment, a comparative example in which the region surrounded by the second diaphragm surface 412 of the nozzle 41 is not narrowed toward the front end side and is constant in width will be described with reference to FIG. To do. In this comparative example, as shown by the dotted line 72 in FIG. 5, the increasing rate of the flow path cross-sectional area is larger than the solid line 71 in the range from the axial position P2 to the axial position P3. In such an example, boiling occurs at the boundary 44x. That is, a boiling delay occurs. Boiling delay means that boiling occurs in the refrigerant flow downstream of the throat 41x. When the boiling delay occurs, it becomes difficult for boiling to occur in the throat 41x. As a result, the energy recovery efficiency of the ejector 40 decreases.

Here, energy recovery efficiency refers to the rate at which loss generated by expansion of the refrigerant can be recovered as kinetic energy. The ejector 40 is designed to maximize energy recovery efficiency by causing boiling at the throat 41x. Therefore, when boiling occurs on the tip side of the nozzle 41, the energy recovery efficiency decreases.

In contrast, in the present embodiment, the region surrounded by the second diaphragm surface 412 becomes narrower toward the tip side. As a result, it is possible to suppress a rapid increase in the cross section of the flow path on the tip side from the boundary portion 44x as compared with the comparative example. As a result, the occurrence of boiling at the boundary portion 44x can be suppressed, and consequently boiling at the throat portion 41x is likely to occur. Therefore, even if a boiling delay occurs, it is possible to suppress a decrease in energy recovery efficiency that occurs due to the boiling delay.

Also, the needle 44 has a tapered second tapered portion 442. As a result, the flow gathers on the axis CL due to the inertial force of the refrigerant. Thereby, appropriate free expansion can be promoted.

As described above, when the entraining action is exerted in the ejector 40, the tip side of the inner wall surface of the nozzle 41 has a shape that narrows the region surrounded by the inner wall surface toward the tip side. With this configuration, boiling at the boundary 44x can be suppressed. As a result, it is possible to suppress a decrease in energy recovery efficiency that occurs due to boiling of the refrigerant at a portion other than the intended portion, resulting in a boiling delay.

(Second Embodiment)
Next, a second embodiment will be described. In the present embodiment, the shape of the needle 44 is changed with respect to the first embodiment. Others are the same as in the first embodiment.

In this embodiment, as shown in FIG. 6, the shape of the portion on the tip side from the boundary portion 44x, that is, the second taper portion 442 is different from that of the first embodiment. In this embodiment, the 2nd taper part 442 is tapering toward the front end side of the ejector 40 similarly to 1st Embodiment. However, unlike the first embodiment, the surface of the tip of the second taper portion 442 is a smooth curved surface. In the first embodiment, the tip of the second taper portion 442 is sharp.

In this way, the entire length of the needle 44 can be suppressed. However, on the other hand, the possibility that vortices are generated on the surface of the second tapered portion 442 is increased.

Also in the present embodiment, the second taper angle θE2, which is the taper angle of the second taper portion 442 at the boundary portion 44x, is larger than the first taper angle θE1. Further, the first taper angle θE1 and the second taper angle θE2 are discontinuous at the boundary portion 44x. Therefore, as in the first embodiment, the area surrounded by the second diaphragm surface 412 becomes narrower toward the distal end side, so that an effect equivalent to that of the first embodiment can be obtained.

(Third embodiment)
Next, a third embodiment will be described. In the present embodiment, the shapes of the first diaphragm surface 411 and the second diaphragm surface 412 are changed with respect to the first embodiment. Others are the same as in the first embodiment. In the present embodiment, as shown in FIG. 7, the cross section when the first diaphragm surface 411 is cut along a plane including the axis line CL is a smooth curve. Similarly, the cross section when the second diaphragm surface 412 is cut along a plane including the axis CL is also a smooth curve.

Therefore, neither the first taper angle θZ1 nor the second taper angle θZ2 is constant. Specifically, the first taper angle θZ1 decreases as it goes toward the tip of the ejector 40. Further, the second taper angle θZ2 decreases toward the tip of the ejector 40, and becomes 0 degree at the forefront of the nozzle 41.

Moreover, in the present embodiment, the first taper angle θZ1 and the second taper angle θZ2 are continuous in the throat portion 41x. That is, the first taper angle θZ1 and the second taper angle θZ2 in the throat portion 41x are the same. By forming the first diaphragm surface 411 and the second diaphragm surface 412 in such a shape, the processing difficulty of the nozzle 41 increases, but the energy recovery efficiency increases.

Even in this case, the portion that minimizes and minimizes the cross-sectional area of the refrigerant flow path between the nozzle 41 and the needle 44 is the boundary between the first throttle surface 411 and the second throttle surface 412. This boundary is the throat 41x.

Also in this embodiment, when the ejector 40 is actuated to exert the entrainment effect, in most cases, the first taper portion 441 faces the throat portion 41x. In this case, depending on the shape of the first taper portion 441, the position of the throat portion 41x may change according to the change in the axial position of the nozzle 41, or the position of the throat portion 41x may be changed to the axial position of the nozzle 41. It may be constant regardless of the case. In any case, when the entrainment effect is exerted, the boundary portion 44x is closer to the distal end side of the ejector 40 than the throat portion 41x. Therefore, also in this embodiment, an effect equivalent to that of the first embodiment can be obtained.

(Fourth embodiment)
Next, a fourth embodiment will be described. The ejector according to the present embodiment is used in an ejector cycle for a vehicle air conditioner. FIG. 8 is a schematic diagram of an ejector cycle using carbon dioxide as a refrigerant.

This ejector cycle is configured to be capable of switching between a cooling operation mode for cooling indoor blown air that is a heat exchange target fluid and a heating operation mode for heating indoor blown air. The solid line arrows in FIG. 8 indicate the refrigerant flow in the cooling operation mode, and the broken line arrows indicate the refrigerant flow in the heating operation mode.

This ejector cycle includes an ejector 40, a compressor 111, an accumulator 114, a throttle 115, a first four-way valve 141, an outdoor heat exchanger 142, a blower 142a, a second four-way valve 143, a use side heat exchanger 144, and a blower 144a. is doing. The structure of the ejector 40 is roughly as shown in FIG. The detailed configuration of the ejector 40 will be described later.

The compressor 111 is a device having the same function as the compressor 10 of the first embodiment. As with the gas-liquid separator 50 of the first embodiment, the accumulator 114 is a gas-liquid that stores the refrigerant by flowing the refrigerant flowing out from the ejector 40 into the vapor-phase refrigerant and the liquid-phase refrigerant. It is a separation part. The gas-phase refrigerant outlet of the accumulator 114 is connected to the suction side of the compressor 111. The liquid-phase refrigerant outlet of the accumulator 114 is connected to the inflow side of the use side heat exchanger 144. The throttle 115 is a decompression unit that decompresses the liquid-phase refrigerant that has flowed out of the accumulator 114.

A first four-way valve 141 is connected to the refrigerant discharge side of the compressor 111. The first four-way valve 141 is an electric refrigerant flow switching unit whose operation is controlled by a control signal output from a control device (not shown). Specifically, the first four-way valve 141 switches between a refrigerant flow path indicated by a solid arrow in FIG. 8 and a refrigerant flow path indicated by a broken arrow in FIG.

In the refrigerant flow path indicated by the solid line arrow in FIG. 8, the outlet side of the compressor 111 and the outdoor heat exchanger 142 are connected, and the outlet side of the throttle 115 and the use side heat exchanger 144 are connected. Is connected. In the refrigerant flow path indicated by the broken line arrow in FIG. 8, the discharge port side of the compressor 111 and the use side heat exchanger 144 are connected, and between the outflow side of the throttle 115 and the outdoor heat exchanger 142. Is connected.

A second four-way valve 143 is connected to the outlet side of the outdoor heat exchanger 142. The second four-way valve 143 is an electric refrigerant flow switching unit whose operation is controlled by a control signal output from the control device. Specifically, the first four-way valve 141 switches between a refrigerant flow path indicated by a solid arrow in FIG. 8 and a refrigerant flow path indicated by a broken arrow in FIG.

In the refrigerant flow path indicated by the solid line arrow in FIG. 8, the outdoor heat exchanger 142 and the high-pressure refrigerant inlet 46a side of the ejector 40 are connected, and the use-side heat exchanger 144 and the low-pressure refrigerant inlet 46b of the ejector 40 are connected. Are connected at the same time. In the refrigerant flow path indicated by the broken line arrow in FIG. 8, the outdoor heat exchanger 142 and the low pressure refrigerant inlet 46b side of the ejector 40 are connected, and the use side heat exchanger 144 and the high pressure refrigerant inlet 46a of the ejector 40 are connected. Are connected at the same time.

The outdoor heat exchanger 142 is a heat exchanger that exchanges heat between the refrigerant flowing out of the first four-way valve 141 and the outdoor air blown by the blower 142a. The use side heat exchanger 144 is a heat exchanger that exchanges heat between the refrigerant passing through the inside and the indoor blown air that is the heat exchange target fluid blown by the blower 144a.

The ejector 40 includes a nozzle 41, a mixing unit 42, a diffuser 43, a needle 44, a housing 45, a block 46, and the like, as in the first embodiment. The components other than the nozzle 41 and the needle 44, such as the mixing unit 42, the diffuser 43, the housing 45, and the block 46, are the same as those in the first embodiment.

Here, the configuration of the needle 44 and the nozzle 41 will be described in more detail. The needle 44 is formed in a conical taper shape so that the cross-sectional area decreases toward the tip end side (that is, the refrigerant outflow side) of the ejector 40. Here, the cross-sectional area refers to a cross-sectional area when cut by a plane perpendicular to the axis of the needle 44. The nozzle 41 and the needle 44 may be made of metal such as stainless steel. The needle 44 is driven by an actuator (not shown) according to the flow rate of the high-pressure refrigerant flowing into the nozzle 41 and can be displaced in the axial direction of the needle 44. The needle 44 is disposed coaxially with the nozzle 41 in the space inside the nozzle 41.

The needle 44 has a body portion 440 and a first taper portion 441 as shown in FIG. The trunk portion 440 and the first taper portion 441 are integrally and coaxially formed as a whole. The body portion 440 has a substantially cylindrical shape, and is connected to the first taper portion 441 on the distal end side.

The first taper portion 441 has a substantially conical shape tapered toward the outflow side (that is, the front end side) of the fluid flow path surrounded by the inner wall surface inside the nozzle 41. In the present embodiment, the first taper angle θE1 that is the Dapper angle of the first taper portion 441 is constant. Therefore, the first taper angle θE1 is constant from the end on the body 440 side to the end on the front end side of the first taper portion 441. In the present embodiment, the second tapered portion 442 shown in the first embodiment does not exist. That is, the first taper portion 441 is a member that is on the most distal end side of the needle 44. And the 1st taper part 441 is sharp in the front end side. Thus, in the present embodiment, the portion on the tip side of the body portion 440 has a constant first taper angle θE1.

Further, the wall surface, that is, the inner wall surface of the nozzle 41 on the needle 44 side has a root surface 410, a first diaphragm surface 411, and a second diaphragm surface 412. The root surface 410, the first diaphragm surface 411, and the second diaphragm surface 412 are disposed coaxially with the body portion 440, the first taper portion 441, and the second taper portion 442. The root surface 410 has a substantially cylindrical shape, and mainly surrounds the body portion 440 and, in some cases, the first taper portion 441 of the needle 44.

The first diaphragm surface 411 is connected to the tip side end of the root surface 410 and further tapers toward the tip side at a first taper angle θZ1. The shape of the first diaphragm surface 411 is substantially the same as the side surface of the truncated cone. Accordingly, the first diaphragm surface 411 is reduced in diameter toward the distal end side. For this reason, the region surrounded by the first diaphragm surface 411 becomes narrower toward the tip side.

The second diaphragm surface 412 is connected to the end of the first diaphragm surface 411 on the distal end side, and further tapers continuously and smoothly at a constant second taper angle θZ2 toward the distal end side. The shape of the second diaphragm surface 412 is substantially the same as the side surface of the cone. Accordingly, the second aperture surface 412 is reduced in diameter toward the tip side.

For this reason, the region surrounded by the second diaphragm surface 412 becomes narrower toward the tip side. In other words, the area of the region surrounded by the second diaphragm surface 412 on a surface passing through a certain axial position and orthogonal to the direction of the axial line CL is continuous as the axial position moves toward the tip. Slowly becomes smaller. The end of the second diaphragm surface 412 on the front end side corresponds to the outlet 41z of the nozzle 41. The refrigerant flows out from the inside of the nozzle 41 through the circular outlet 41z.

Thus, the outlet 41z is located on the inner wall surface of the nozzle 41 at the end of the ejector 40 in the fluid flow path. The throat portion 41x is located on the opposite side of the distal end side from the outlet 41z and protrudes toward the needle 44. The reason why the throat portion 41x protrudes toward the needle 44 is that the first taper angle θZ1 is larger than the second taper angle θZ2.

The diameter of the outlet 41z is smaller than the diameter of the throat 41x. Therefore, the circumference of the outlet 41z is shorter than the circumference of the throat 41x. Here, the circumferential length of the throat portion 41x is a length that goes around the axis of the nozzle 41 along the throat portion 41x. Further, the peripheral length of the outlet 41z is a length that goes around the axis of the nozzle 41 along the outlet 41z.

Further, the second taper angle θZ2 that is the taper angle of the second diaphragm surface 412 is smaller than the first taper angle θE1 described above. Further, the first taper angle θZ1 and the second taper angle θZ2 are discontinuous at the throat portion 41x corresponding to the boundary between the first diaphragm surface 411 and the second diaphragm surface 412.

Here, the flow path cross-sectional area of the gap between the nozzle 41 and the needle 44 will be described. Here, the flow path cross-sectional area at a certain axial position refers to the area of the gap between the nozzle 41 and the needle 44 in a cross section passing through the axial position and orthogonal to the axis CL. However, if the needle 44 is not present in the cross section, the area of the portion surrounded by the nozzle 41 in the cross section becomes the flow path cross sectional area.

The channel cross-sectional area of the gap between the nozzle 41 and the needle 44 varies depending on the position in the axial direction, as indicated by

solid lines

73 and 74 in FIGS. In addition, the correspondence between the axial position and the channel cross-sectional area changes as the needle lift amount changes.

Here, the needle lift amount is an amount indicating the relative position of the needle 44 to the nozzle 41 in the axial direction. The needle lift amount is zero when the first taper portion 441 of the needle 44 is in contact with the throat portion 41x of the nozzle 41 (ie, the valve is closed). In a state where the needle 44 has moved by a predetermined movement amount in the root direction of the needle 44 (that is, the valve opening direction) rather than the valve closing state, the predetermined movement amount corresponds to the needle lift amount. That is, the needle lift amount is an amount indicating the degree of separation of the needle 44 from the nozzle 41 in the axial direction. In the present embodiment, the needle 44 moves in the axial direction of the needle 44 with respect to the nozzle 41.

The needle lift amount in the state of FIG. 10 is smaller than the needle lift amount in the state of FIG. In the state of FIG. 10, the cross-sectional area of the flow path is the minimum and minimum at the position of the throat portion 41x, increases from the throat portion 41x toward the root side, and increases from the throat portion 41x toward the distal end side. Become. In this case, the nozzle 41 and the needle 44 operate as a Laval nozzle.

On the other hand, in the state shown in FIG. 11, the cross-sectional area of the flow path is neither minimum nor minimum at the position of the throat portion 41x. That is, the channel cross-sectional area is smaller from the root side toward the throat part 41x than the throat part 41x, and is smaller from the throat part 41x toward the distal end side. At this time, the decreasing gradient of the channel cross-sectional area from the base side toward the throat 41x is larger than the decreasing gradient of the channel cross-sectional area from the throat 41x toward the tip side than the throat portion 41x. In this case, the nozzle 41 and the needle 44 operate as a plug nozzle.

The reason why the ejector 40 operates as a Laval nozzle or a plug nozzle depending on the needle lift amount will be described below. Assuming that the channel cross-sectional area at the throat 41x is A1, and the channel cross-sectional area at the outlet 41z is A2, A1 and A2 are expressed by the following equations.
A1 = π × r4 ² −π × r3 ² = π × r4 ² −π × (r4−R × tan (θE1 / 2)) ²
A2 = π × r2 ² −π × r1 ² = π × r2 ² −π × (r3−L × tan (θE1 / 2)) ²
= Π × (r4-L × tan (θZ2 / 2)) ²
−π × (r4−R × tan (θE1 / 2) −L × tan (θE1 / 2)) ²
Here, R is the needle lift amount. L is the absolute value of the difference between the axial position of the outlet 41z and the axial position of the throat 41x, that is, the tip length. r1 is a radius of the first tapered portion 441 of the needle 44 in a cross section including the outlet 41z and orthogonal to the axis CL. r2 is the radius of the exit 41z. r3 is a radius of the first tapered portion 441 of the needle 44 in a cross section including the throat portion 41x and orthogonal to the axis line CL. r4 is the radius of the throat 41x. Note that these formulas indicate that the tip of the first taper portion 441 of the needle 44 protrudes out of the outlet 41z, that is, the tip of the first taper portion 441 is located on the tip side of the outlet 41z. It is assumed.

As shown in FIG. 10, when the nozzle 41 and the needle 44 operate as a Laval nozzle, since A1 <A2,
Y = (tan (θE1 / 2) −tan (θZ2 / 2)) × (2 × r4−L × tan (θZ2 / 2) −L × tan (θE1 / 2)) / (2 × tan ² (θE1 / 2))> R.

The value Y in the above formula is a design value determined only by the shape of the nozzle 41 and the needle 44. Therefore, when the needle lift amount R is smaller than the design value Y, the nozzle 41 and the needle 44 operate as a Laval nozzle. When the needle lift amount R is larger than the design value Y, the nozzle 41 and the needle 44 operate as plug nozzles. In order for the design value Y to be a positive value, it is necessary that θE1> θZ2.

Thus, since the first taper angle θE1 of the needle 44 is larger than the second taper angle θZ2 of the nozzle 41, the ejector 40 operates as a Laval nozzle or a plug nozzle depending on the amount of needle lift.

In the present embodiment, in the valve-closed state, the first tapered portion 441 of the needle 44 and the throat portion 41x of the nozzle 41 are in contact, and a gap exists between the needle 44 and the outlet 41z. Therefore, in the valve opening state in which the needle lift amount is greater than zero, the ejector 40 operates as a Laval nozzle or a plug nozzle depending on the needle lift amount.

In the closed state, the tip of the first taper portion 441 of the needle 44 is on the tip side of the outlet 41z. The inner wall surface of the nozzle 41 has an inclination that tapers toward the tip end side of the ejector 40 at the outlet 41z. Therefore, in the valve open state, the ability of the ejector 40 can be easily adjusted by adjusting the needle lift amount and adjusting the flow path cross-sectional area at the outlet 41z. If the outlet 41z is not inclined toward the front end side of the ejector 40 on the inner wall surface of the nozzle 41, the outlet 41z does not have a minimum channel cross-sectional area. It becomes difficult to adjust the capacity of the ejector 40 by adjusting the above. This is because the needle 44 is on the tip side with respect to the outlet 41z, and the needle 44 is tapered toward the tip side.

Furthermore, even when the needle lift amount R is larger than the design value Y, the tip of the first taper portion 441 of the needle 44 is located on the tip side of the ejector 40 from the outlet 41z. Therefore, the capacity adjustment of the ejector 40 can be easily performed. That is, regardless of whether the ejector 40 operates as a Laval nozzle or a plug nozzle, the ability of the ejector 40 can be adjusted by adjusting the needle lift amount R.

The entraining action of the ejector 40 in this embodiment is the same as in the first, second, and third embodiments. That is, the fluid outside the nozzle 41 is sucked by the entraining action of the working fluid ejected from the tip end side of the ejector 40 in the nozzle 41 through the fluid flow path inside the nozzle 41.

Next, the operation of the ejector cycle having the above configuration will be described. In the ejector cycle of the present embodiment, it is possible to switch between a cooling operation mode for cooling indoor blown air and a heating operation mode for heating indoor blown air.

a. Cooling operation mode The cooling operation mode is executed when the cooling operation mode is selected by an operation switch of an operation panel (not shown). In the cooling operation mode, the control device operates the compressor 111, the blower 142a, and the blower 144a, and switches the first four-way valve 141 and the second four-way valve 143 so that the refrigerant flow path becomes a solid line arrow in FIG.

Accordingly, as indicated by the solid line arrow in FIG. 5, the compressor 111, the first four-way valve 141, the outdoor heat exchanger 142, the second four-way valve 143, the high-pressure refrigerant inlet 46a of the ejector 40, the outlet 45a of the ejector 40, and the accumulator 114 The refrigerant circulates in the order of the gas-phase refrigerant outlet and the compressor 111. At the same time, a cycle in which the refrigerant circulates in the order of the liquid-phase refrigerant outlet of the accumulator 14, the throttle 115, the first four-way valve 141, the use side heat exchanger 144, the second four-way valve 143, the low-pressure refrigerant inlet 46b of the ejector 40, and the accumulator 114. Is configured.

Therefore, the refrigerant compressed by the compressor 111 is cooled by exchanging heat with the outside air blown by the blower 142a in the outdoor heat exchanger 142, and isentropically decompressed and expanded by the nozzle 41 of the ejector 40. Be injected. Due to the suction action of the injected refrigerant, the refrigerant flowing out from the use side heat exchanger 144 is sucked into the low-pressure refrigerant inlet 46b.

Further, in the ejector 40, the refrigerant injected from the nozzle 41 and the refrigerant sucked from the low-pressure refrigerant inlet 46b are mixed in the mixing unit 42 and pressurized by the diffuser 43. The refrigerant flowing out from the diffuser 43 through the outlet 45a is gas-liquid separated by the accumulator 114, and the gas phase refrigerant flowing out from the gas phase refrigerant outlet of the accumulator 114 is sucked into the compressor 111 and compressed again. The

On the other hand, the liquid-phase refrigerant that has flowed out from the liquid-phase refrigerant outlet of the accumulator 114 is further decompressed and expanded in an isenthalpy manner at the throttle 115 and flows into the use-side heat exchanger 144 via the first four-way valve 141. It absorbs heat from the indoor air blown by the blower 144a and evaporates. Thereby, indoor ventilation air is cooled. The refrigerant flowing out from the use side heat exchanger 144 is sucked into the low-pressure refrigerant inlet 46b through the second four-way valve 143.

As described above, in the cooling operation mode of the present embodiment, the refrigerant discharged from the compressor 111 is radiated by the outdoor heat exchanger 142, and the refrigerant is evaporated by the use side heat exchanger 144. ing. Therefore, indoor air can be cooled in the cooling operation mode of the present embodiment.

b. Heating operation mode The heating operation mode is executed when the heating operation mode is selected by an operation switch of an operation panel (not shown). In the heating operation mode, the control device operates the compressor 111, the blower 142a, and the blower 144a, and switches the first four-way valve 141 and the second four-way valve 143 so that the refrigerant flow path becomes a broken line arrow in FIG.

Thereby, as indicated by the broken line arrows in FIG. 8, the gas phase refrigerant of the compressor 111, the first four-way valve 141, the use side heat exchanger 144, the second four-way valve 143, the ejector 40, the high-pressure refrigerant inlet 46 a, and the accumulator 114. The refrigerant circulates in the order of the outlet and the compressor 111. At the same time, there is a cycle in which the refrigerant circulates in the order of the liquid refrigerant outlet of the accumulator 114, the throttle 115, the first four-way valve 141, the outdoor heat exchanger 142, the second four-way valve 143, the low-pressure refrigerant inlet 46b of the ejector 40, and the accumulator 14. Composed.

Therefore, the refrigerant compressed by the compressor 111 exchanges heat with the indoor blown air blown by the blower 144a in the use side heat exchanger 144 and dissipates heat. Thereby, indoor blowing air is heated. The refrigerant radiated and cooled by the use side heat exchanger 144 is decompressed and expanded in an isentropic manner by the nozzle 41 of the ejector 40 and is injected. Due to the suction action of the injected refrigerant, the refrigerant flowing out of the outdoor heat exchanger 142 is sucked into the low-pressure refrigerant inlet 46b.

Further, in the ejector 40, the injection refrigerant injected from the nozzle 41 and the suction refrigerant sucked into the low-pressure refrigerant inlet 46b are mixed in the mixing section 42 and pressurized by the diffuser 43. The refrigerant flowing out of the diffuser 43 is gas-liquid separated by the accumulator 114, and the gas phase refrigerant flowing out from the gas phase refrigerant outlet is sucked into the compressor 111 and compressed again.

On the other hand, the liquid-phase refrigerant that has flowed out from the liquid-phase refrigerant outlet of the accumulator 114 is further decompressed and expanded in an isenthalpy manner at the throttle 115 and flows into the outdoor heat exchanger 142 via the first four-way valve 141. It absorbs heat from the outside air blown by the blower 142a and evaporates. The refrigerant flowing out of the outdoor heat exchanger 142 is sucked into the low-pressure refrigerant inlet 46b.

That is, in the heating operation mode of the present embodiment, the refrigerant discharged from the compressor 111 is dissipated by the use side heat exchanger 144 and the outdoor heat exchanger 142 is switched to the refrigerant flow path for evaporating the refrigerant. . Therefore, indoor air can be heated in the heating operation mode of the present embodiment.

In both the cooling operation mode and the heating operation mode, the control device adjusts the refrigerant flow rate by adjusting the needle lift amount and the like. The needle lift amount is realized by a control device driving a drive mechanism (not shown) (for example, a rotor and a stator) that changes the position of the needle 44 with respect to the nozzle 41.

The refrigerant flow rate is the amount of refrigerant flowing in the nozzle 41 per unit time. In the cooling operation mode, the cooling capacity in the passenger compartment is adjusted by adjusting the refrigerant flow rate. In the heating operation mode, the heating capacity in the passenger compartment is adjusted by adjusting the refrigerant flow rate.

FIG. 12 shows the throat channel cross-sectional area 200 and the outlet channel cross-sectional area 201 in the range of the needle lift amount R realized in the cooling operation mode and the heating operation mode of the present embodiment. The throat channel cross-sectional area 200 is the channel cross-sectional area of the gap between the nozzle 41 and the needle 44 in the throat 41x. The outlet channel cross-sectional area 201 is the channel cross-sectional area of the gap between the nozzle 41 and the needle 44 at the outlet 41z.

12, the solid line indicating the throat channel cross-sectional area 200 and the solid line indicating the outlet channel cross-sectional area 201 intersect at a point 203. Therefore, at the needle lift amount R smaller than the needle lift amount R corresponding to this point 203, the outlet flow passage cross-sectional area 201 is larger than the throat flow passage cross-sectional area 200. Then, at the needle lift amount R larger than the needle lift amount R corresponding to the point 203, the throat channel cross-sectional area 200 is larger than the outlet channel cross-sectional area 201.

Due to this behavior of the channel cross-sectional area, the throat portion 41x becomes the choke point having the smallest channel cross-sectional area in the region surrounded by the rectangle 210, and the outlet 41z flows most in the region surrounded by the rectangle 220. The choke point has a small road cross-sectional area. The choke point is a position where the refrigerant passing through the nozzle 41 exceeds the speed of sound.

Since this is the case, in the range of the needle lift amount R corresponding to the region surrounded by the rectangle 210 (that is, the first range), the nozzle 41 and the needle 44 operate as a Laval nozzle. In the range of the needle lift amount R corresponding to the area surrounded by the rectangle 220 (that is, the second range), the nozzle 41 and the needle 44 operate as plug nozzles.

For example, the control device may realize the rated cooling operation in the cooling operation mode. In this case, the control device controls the ejector 40 so that the needle lift amount R becomes a value C1 in the rectangle 220 as shown in FIG. 12 in order to maximize the cooling capacity by increasing the refrigerant flow rate. In this case, the nozzle 41 and the needle 44 are in the state shown in FIG. 11, and operate as a plug nozzle.

Also, for example, in the cooling operation mode, the cooling intermediate operation may be realized. In that case, in order to reduce the cooling capacity by reducing the refrigerant flow rate (for example, up to half) from the above-described cooling rated operation, the control device reduces the cooling capacity, so that the needle lift amount R is a value C2 within the rectangle 210 as shown in FIG. The ejector 40 is controlled so that In this case, the nozzle 41 and the needle 44 are in a state as shown in FIG. 10, and operate as a Laval nozzle.

For example, the control device may realize a heating rated operation in the heating operation mode. In this case, the control device controls the ejector 40 so that the needle lift amount R becomes a value H1 in the rectangle 210, as shown in FIG. 12, in order to maximize the heating capacity by increasing the refrigerant flow rate. In this case, the nozzle 41 and the needle 44 are in a state as shown in FIG. 10, and operate as a Laval nozzle.

Also, for example, in the heating operation mode, an intermediate cooling operation may be realized. In that case, in order to reduce the heating capacity by reducing the refrigerant flow rate (for example, up to half) from the above-mentioned heating rated operation, the control device reduces the heating capacity to a value H2 within the rectangle 210 as shown in FIG. The ejector 40 is controlled so that In this case, the nozzle 41 and the needle 44 are in a state as shown in FIG. 10, and operate as a Laval nozzle.

The effect of the ejector 40 that realizes the above-described configuration and operation will be described below. In the conventional ejector, the inner wall surface of the nozzle is not tapered but has a straight cylindrical shape on the tip side of the throat. On the other hand, the inner wall surface of the nozzle 41 of the present embodiment tapers continuously and smoothly from the throat 41x to the outlet 41z.

When the operating conditions of the ejector 40 are determined, the minimum value of the channel cross-sectional area in the nozzle 41 and the outlet channel cross-sectional area can be determined from the characteristics of the refrigerant. When the ejector 40 is a constituent element of the air conditioner as in the present embodiment, the operation condition varies greatly depending on the operation mode such as cooling or heating, and the refrigerant flow rate according to the capacity. And it is difficult to maintain the above-mentioned optimal shape in a plurality of operating conditions.

For example, FIG. 13 shows an example of operating conditions of an ejector when an ejector having a straight cylindrical shape on the tip side from the throat is used in an air conditioner, unlike the present embodiment. In this example, the choke point is always at the throat regardless of the amount of needle lift.

In the graph of FIG. 13, the vertical axis represents the throat flow path cross-sectional area, and the horizontal axis represents the needle lift amount. The

solid lines

250, 260, 270, and 280 are throat flow paths when nozzles having straight portions of 0.5 mm, 1.0 mm, 2.0 mm, and 3.0 mm are used, respectively. The relationship between a cross-sectional area and a needle lift amount is shown. The length of the straight portion is a length along the axis CL from the throat portion to the needle. It is very difficult to process a nozzle having a straight portion shorter than 0.5 mm. Therefore, a nozzle having a straight part length of 0.5 mm is a nozzle that is at the processing limit.

Black circles

251, 252, 253, and 254 in the figure respectively show the optimum outlet channel cross-sectional area in the needle lift amount that realizes the above-described intermediate heating operation, heating rated operation, cooling intermediate operation, and cooling rated operation. . As shown in FIG. 13, the optimum throat channel cross-sectional area and the outlet channel cross-sectional area greatly differ depending on cooling and heating, or depending on the air-conditioning capability (ie, rated or intermediate).

Thus, if the ejector is not operated with the optimal throat channel cross-sectional area and outlet channel cross-sectional area according to the operating conditions, the efficiency will decrease. For example, when the outlet channel cross-sectional area is larger than the optimum value, a state called overexpansion that falls below the target nozzle outlet pressure occurs, and a shock wave is generated near the nozzle outlet, resulting in energy loss. When the outlet channel cross-sectional area is small, the underexpanded state is higher than the target outlet pressure, and the subsequent section becomes free expansion. In the case of free expansion, a pseudo wall is created by the expansion wave, so operation is similar to a Laval nozzle. Therefore, although the efficiency is inferior to that of the optimum Laval nozzle, the performance degradation is smaller than the overexpansion. In the conventional nozzle, since the cross-sectional area of the flow path of the nozzle spreads from the throat to the outlet or becomes substantially constant, nothing is considered to suppress the above-described overexpansion.

Even if it is going to suppress overexpansion in any of the above-mentioned heating intermediate operation, heating rated operation, cooling intermediate operation, and cooling rated operation, the cooling intermediate operation corresponding to the black circle 253 becomes overexpanded due to the above processing limit. . That is, the nozzle shown by the solid line 250 has an optimum outlet flow passage cross-sectional area in the middle of heating and underexpands in the heating rated operation and cooling rated operation, but the cooling intermediate operation becomes overexpanded.

Also, in the case of a conventional ejector, when the needle lift amount is large, the cross-sectional area of the outlet channel of the nozzle may become large, resulting in excessive expansion. As a countermeasure, there is a method of shortening the distance from the throat to the outlet in order to reduce the sectional area of the outlet channel. However, if the distance from the throat to the outlet is shortened, the nozzle efficiency is deteriorated. This is because, in order to increase the nozzle efficiency, it is generally desirable to gradually increase the flow path cross-sectional area from the throat to the outlet. On the other hand, in this embodiment, overexpansion can be suppressed without shortening the distance from the throat to the outlet.

In this embodiment, since high efficiency is required in a low flow rate region where the needle lift amount is small, the nozzle 41 operates as a Laval nozzle. On the other hand, in the high flow rate region where the needle lift amount is large, the same nozzle 41 operates as a plug nozzle. As described above, the choke point is changed, so that the width of the optimum operation region can be widened. Since the optimum Laval nozzle shape is more efficient than the plug nozzle shape, this embodiment is superior to the case where all regions are plug nozzles.

In the present embodiment, the needle 44 and the inner wall surface of the nozzle 41 are in contact with each other in the valve-closed state. Of the first taper portion 441 of the needle 44, the first taper angle θE1 of the portion in contact with the inner wall surface in the valve-closed state and the portion on the tip side of the portion is the outlet 41z of the inner wall surface of the nozzle 41. Is larger than the second taper angle θZ2. Further, in the valve-closed state, the needle 44 and the inner wall surface of the nozzle 41 are in contact with each other, and a gap exists between the needle 44 and the outlet 41z. By doing so, the operation as a Laval nozzle and the operation as a plug nozzle can be switched reliably.

(Fifth embodiment)
Next, a fifth embodiment will be described. In the present embodiment, the shape of the needle 44 is changed with respect to the fourth embodiment. Others are the same as in the fourth embodiment.

In this embodiment, as shown in FIG. 14, only the shape of the tip side portion of the first taper portion 441 is different from that of the fourth embodiment. In the present embodiment, the base side portion of the first taper portion 441 is tapered in a conical shape with a constant taper angle toward the tip end side of the ejector 40 as in the fourth embodiment. However, unlike the fourth embodiment, the surface of the tip side portion of the first taper portion 441 is a smooth curved surface with a rounded tip and no pointed portion. With this configuration, the entire length of the needle 44 can be suppressed.

Also in the present embodiment, the taper angle of the portion on the base side of the first taper portion 441 is larger than the second taper angle θZ2 of the nozzle 41. Further, the taper angle at any position of the tip side portion of the first taper portion 441 is larger than the second taper angle θZ <b> 2 of the nozzle 41.

Also in the present embodiment, in the first range of the needle lift amount R corresponding to the region surrounded by the rectangle 210 in FIG. 12, the throat flow path cross-sectional area is smaller than the outlet flow path cross-sectional area. The needle 44 operates as a Laval nozzle. Then, in the second range of the needle lift amount R corresponding to the region surrounded by the rectangle 220 in FIG. 12, the throat section channel cross-sectional area is larger than the outlet channel cross-sectional area, so that the nozzle 41 and the needle 44 are plugged. Operates as a nozzle.

(Sixth embodiment)
Next, a sixth embodiment will be described. In the present embodiment, the shapes of the first diaphragm surface 411 and the second diaphragm surface 412 are changed with respect to the fourth embodiment. Others are the same as in the fourth embodiment. In the present embodiment, as shown in FIG. 15, the cross section when the first diaphragm surface 411 is cut along a plane including the axis line CL is a smooth curve. Similarly, the cross section when the second diaphragm surface 412 is cut along a plane including the axis CL is also a smooth curve.

Therefore, neither the first taper angle θZ1 nor the second taper angle θZ2 is constant. Specifically, the first taper angle θZ1 decreases as it goes toward the tip of the ejector 40. Further, the second taper angle θZ2 decreases as it goes toward the tip of the ejector 40. However, the second taper angle θZ2 is a positive value even at the outlet 41z. That is, the second diaphragm surface 412 has a tapered gradient at the outlet 41z.

In the present embodiment, the first taper angle θZ1 and the second taper angle θZ2 are continuous in the throat 41x. That is, the first taper angle θZ1 and the second taper angle θZ2 in the throat portion 41x are the same. By forming the first diaphragm surface 411 and the second diaphragm surface 412 in such a shape, the processing difficulty of the nozzle 41 increases, but the energy recovery efficiency increases.

(Other embodiments)
Note that the present disclosure is not limited to the above-described embodiment, and can be modified as appropriate. Further, the above embodiments are not irrelevant to each other, and can be combined as appropriate unless the combination is clearly impossible. In each of the above-described embodiments, the elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Further, in each of the above embodiments, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is clearly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to the specific number except for the case. In the above embodiment, when it is described that external environment information (for example, humidity outside the vehicle) is acquired from a sensor, the sensor is discarded and the external environment information is received from a server or cloud outside the vehicle. It is also possible to do. Alternatively, it is possible to eliminate the sensor, acquire related information related to the external environment information from a server or cloud outside the vehicle, and estimate the external environment information from the acquired related information. In particular, when a plurality of values are exemplified for a certain amount, it is also possible to adopt a value between the plurality of values unless specifically stated otherwise and in principle impossible. . Further, in each of the above embodiments, when referring to the shape, positional relationship, etc. of the component, etc., the shape, unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to the positional relationship or the like. In addition, the present invention allows the following modifications and equivalent modifications of the above embodiments. In addition, the following modifications can select application and non-application to the said embodiment each independently. In other words, any combination of the following modifications can be applied to the above-described embodiment.

(Modification 1)
In the said embodiment, the ejector 40 is used for the ejector cycle for vehicle air conditioners. However, this is not necessarily the case. For example, it may be used for a water heater.

(Modification 2)
In the above embodiment, the first taper angle θZ1 of the nozzle 41 is larger than the second taper angle θZ2. However, this is not necessarily the case. When the entraining action is exerted in the ejector 40, if the boundary portion 44x is closer to the distal end than the throat portion 41x, the relationship between the first taper angle θZ1 and the second taper angle θZ2 is whatever. Good.

(Modification 3)
The ejector 40 of the first, second, and third embodiments may be used for the ejector cycle of the fourth embodiment. In that case, the needle lift amount of the ejector 40 is variable. When the needle lift amount is in the first range, the above-described cooling intermediate operation, heating rated operation, and heating intermediate operation are realized. In this first range, the channel cross-sectional area between the nozzle 41 and the needle 44 is minimum and minimal at the position of the throat portion 41x, and the throat channel cross-sectional area is smaller than the outlet channel cross-sectional area. Further, when the needle lift amount is in the second range that is larger than the first range, the cooling rated operation is realized. In this second range, the channel cross-sectional area between the nozzle 41 and the needle 44 is minimum at the position of the throat 41x, and the throat channel cross-sectional area is larger than the outlet channel cross-sectional area. Further, when the needle lift amount is larger than the design value Y, the tip of the first taper portion 441 of the needle 44 is on the tip side of the outlet 41z. Therefore, the same effect as the fourth embodiment can be obtained.

(Modification 4)
The ejectors 40 in the fourth and subsequent embodiments may be used in cycles other than the ejector cycle as shown in FIG. For example, it may be used for an ejector cycle in which only cooling is possible between cooling and heating, and the cooling capacity is adjusted by adjusting the needle lift amount. Alternatively, it may be used for an ejector cycle in which only heating is possible between cooling and heating, and the cooling capacity is adjusted by adjusting the needle lift amount.

(Modification 5)
In the above embodiment, when the needle lift amount R is larger than the design value Y, the tip of the first tapered portion 441 of the needle 44 is on the tip side of the outlet 41z. However, this need not be the case. That is, when the needle lift amount R is larger than the design value Y, the tip of the first tapered portion 441 of the needle 44 may be closer to the root side than the outlet 41z.

(Summary)
According to the first aspect shown in part or all of the above embodiments, in the ejector, when the needle lift amount is in the first range, the throat channel cross-sectional area is smaller than the outlet channel cross-sectional area. In addition, among the areas of the gaps between the nozzle and the needle in all cross sections orthogonal to the axial direction in the fluid flow path, the throat flow path cross-sectional area is the smallest, and the needle lift amount is less than the first range. When in the large second range, the cross-sectional area of the throat channel is larger than the cross-sectional area of the outlet channel, and the area of the gap between the nozzle and the needle in all cross sections orthogonal to the axial direction in the fluid channel Of these, the outlet channel cross-sectional area is the smallest.

Further, according to the second aspect, the wall surface is tapered toward the tip side at the outlet. Thus, when the tip of the needle is on the tip side of the outlet, the ability of the ejector can be easily achieved by adjusting the needle lift amount and adjusting the cross-sectional area of the flow path at the outlet. it can.

Further, according to the third aspect, the wall surface of the nozzle and the needle are in contact with each other in the valve-closed state, and the portion of the needle that is in contact with the wall surface of the nozzle in the valve-closed state and the tip side of the portion. The taper angle of the part is larger than the taper angle at the outlet of the nozzle wall. By doing so, the operation as a Laval nozzle and the operation as a plug nozzle can be switched reliably.

Further, according to the fourth aspect, in the second range, a part of the needle is on the tip side from the outlet. In this way, the ability adjustment of the ejector can be easily performed. That is, regardless of whether the ejector operates as a Laval nozzle or as a plug nozzle, the ability of the ejector can be adjusted by adjusting the needle lift amount.

Further, according to the fifth aspect, the needle is tapered to the tip side of the first taper portion, and the second taper is further tapered toward the tip side while being connected to the tip side end of the first taper portion. And the second taper angle of the second taper portion at the boundary portion is larger than the first taper angle of the taper angle of the first taper portion at the boundary portion between the first taper portion and the second taper portion. The taper angle is larger, and in the throat, the flow path cross-sectional area of the gap between the nozzle and the needle is minimized, and when the entrainment action is exerted, the boundary portion is closer to the tip than the throat. Yes, when the entrainment action is exerted, the portion of the wall surface closer to the tip side than the throat has a shape that narrows the region surrounded by the wall surface toward the tip side.

Further, according to the sixth aspect, the taper angle at which the wall surface tapers toward the tip side on the tip side from the throat is smaller than the first taper angle. In this way, a shape is realized in which the cross-sectional area of the flow path between the nozzle and the needle increases from the throat to the tip side.

Further, according to the seventh aspect, when the entraining action is exerted in the ejector, the portion on the tip side of the throat portion of the wall surface on the needle side of the nozzle faces the region surrounded by the wall surface toward the tip side. And has a narrowing shape.

Claims

An ejector,
A nozzle (41);
A needle (44) disposed in the fluid flow path inside the nozzle, moving in the axial direction relative to the nozzle and tapering toward the tip end side of the ejector,
Through the entraining action of the working fluid ejected from the tip end side of the ejector in the nozzle through the fluid flow path inside the nozzle, the fluid outside the nozzle is sucked,
The wall surface of the nozzle on the needle side is located at the end (41z) located at the end on the tip side of the fluid flow path, and is located on the side opposite to the tip side from the outlet toward the needle. Projecting throat (41x),
Throat channel cross-sectional area (200) is the area of the gap between the nozzle and the needle in a cross section passing through the throat and orthogonal to the axial direction,
The outlet channel cross-sectional area (201) is the area of the gap between the nozzle and the needle in a cross section passing through the outlet and orthogonal to the axial direction,
When the needle lift amount (R) indicating the degree of separation of the needle with respect to the nozzle in the axial direction is in the first range, the throat channel cross-sectional area is smaller than the outlet channel cross-sectional area, and the fluid Of the area of the gap between the nozzle and the needle in all cross sections orthogonal to the axial direction in the flow channel, the throat flow channel cross-sectional area is the smallest,
When the needle lift amount is in a second range that is larger than the first range, the throat channel cross-sectional area is larger than the outlet channel cross-sectional area and is orthogonal to the axial direction in the fluid channel. An ejector in which the outlet channel cross-sectional area is the smallest among the areas of the gaps between the nozzle and the needle in all cross sections.
The ejector according to claim 1, wherein the wall surface is tapered toward the tip side at the outlet.
In the valve closed state, the wall surface of the nozzle and the needle are in contact with each other,
The taper angle of a portion of the needle that is in contact with the wall surface of the nozzle in a valve-closed state and a portion that is closer to the tip than the portion is larger than a taper angle at the outlet of the wall surface of the nozzle. 2. The ejector according to 2.
The ejector according to any one of claims 1 to 3, wherein in the second range, a part of the needle is located on the tip side from the outlet.
The needle has a first taper portion (441) that tapers toward the tip end side, and a second taper portion that connects to the tip end side end of the first taper portion and tapers further toward the tip end side ( 442), and
The taper of the second taper portion at the boundary is greater than the first taper angle (θE1) that is the taper angle of the first taper at the boundary (44x) between the first taper and the second taper. The second taper angle (θE2) that is an angle is larger,
In the throat, the flow passage cross-sectional area of the gap between the nozzle and the needle is minimized,
When the entrainment effect is exerted, the boundary portion is on the tip side than the throat portion,
5. The device according to claim 1, wherein when the entrainment action is exerted, a portion of the wall surface closer to the distal end than the throat portion has a shape that narrows a region surrounded by the wall surface toward the distal end side. The ejector as described in one.
6. The ejector according to claim 5, wherein a taper angle (θZ <b> 2) at which the wall surface tapers toward the tip side on the tip side of the throat is smaller than the first taper angle.
An ejector,
A nozzle (41);
A needle (44) disposed in a fluid flow path inside the nozzle,
Through the entraining action of the working fluid ejected from the tip end side of the ejector in the nozzle through the fluid flow path inside the nozzle, the fluid outside the nozzle is sucked,
The needle has a first taper portion (441) that tapers toward the tip end side, and a second taper portion that connects to the tip end side end of the first taper portion and tapers further toward the tip end side ( 442), and
The taper of the second taper portion at the boundary is greater than the first taper angle (θE1) that is the taper angle of the first taper at the boundary (44x) between the first taper and the second taper. The second taper angle (θE2) that is an angle is larger,
A wall surface on the needle side of the nozzle is formed with a throat portion (41x) that minimizes a flow passage cross-sectional area of the gap between the nozzle and the needle,
When the entrainment effect is exerted, the boundary portion is on the tip side than the throat portion,
The ejector having a shape in which, when the entraining action is exerted, a portion of the wall surface closer to the distal end than the throat portion narrows a region surrounded by the wall surface toward the distal end side.