JP2019173573A - Ejector, fuel cell system and ejector-type refrigeration cycle - Google Patents

Abstract

To provide an ejector in which the linearity of a change of a flow volume with respect to a valve-opening time per one-control cycle can be improved.SOLUTION: An ejector 20 comprises a nozzle part 202, a suction part 208, a diffuser part 210 and a valve part 214. The nozzle part 202 forms a nozzle part flow passage 204 in which a first fluid flows. The valve part 214 forms a valve part flow passage 215 continuous with an upstream side of the nozzle part flow passage 204, and opens and closes the valve part flow passage 215. The nozzle flow passage 204 includes a throttle part 204a in which a flow passage cross section area becomes the smallest. The valve part flow passage 215 includes the smallest part 215a in which the flow passage cross section area become the smallest. A flow passage of the first fluid between the smallest part 215a and the throttle part 204a is a throttle part upstream-side flow passage 222. An average value of the pressure of the first fluid in the throttle part upstream-side flow passage 222 in a period in which the valve part 214 is in a valve-opening state is smaller than critical pressure which is defined on the basis of a critical pressure ratio of the first fluid and the pressure of the smallest part at an inlet side.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an ejector, a fuel cell system, and an ejector refrigeration cycle.

  Patent Document 1 discloses an ejector in which a valve portion is provided upstream of a nozzle portion. In this ejector, the shape of the flow path inside the ejector is fixed. In this ejector, the flow rate of the fluid ejected from the nozzle portion is adjusted by opening and closing the valve portion. In the adjustment of the flow rate of the fluid ejected from the nozzle part, the valve opening state and the valve closing state of the valve part are repeated alternately. The period from the start of valve opening to the start of the next valve opening is one control cycle. In other words, a period in which one valve opening state and the next one valve closing state are combined is one control cycle.

JP 2008-190336 A

  By the way, this inventor examined utilization of the ejector of the above configuration.

  In general, when a fluid device including a valve portion and a nozzle portion is designed on the premise of a steady flow, the throttle diameter of the valve portion is set to be sufficiently larger than the throttle diameter of the nozzle portion. This is to reduce pressure loss at the valve portion when the valve portion is fully open. The throttle diameter here refers to the flow path width at the portion where the cross-sectional area of the flow path is minimum when the valve section is in the open state. The term “diaphragm diameter of the nozzle part” as used herein refers to the flow path width at the throttle part where the flow path cross-sectional area is the smallest among the flow paths formed by the nozzle part.

  Therefore, the present inventor investigated the performance of the ejector having the above configuration in which the throttle diameter of the valve portion was set sufficiently larger than the throttle diameter of the nozzle portion. As a result, the present inventors have found that the ejector set in this way has a low linearity of change in flow rate with respect to the valve opening time per control cycle.

  An object of the present invention is to provide an ejector capable of enhancing the linearity of a change in flow rate with respect to a valve opening time per control cycle. Another object of the present invention is to provide a fuel cell system provided with this ejector. Another object of the present invention is to provide an ejector refrigeration cycle including the ejector.

In order to achieve the above object, an ejector according to claim 1 comprises:
One or more nozzle parts (202) for forming a nozzle part flow path (204) through which the first fluid flows and ejecting the first fluid flowing through the nozzle part flow path;
A suction part (208) for sucking the second fluid by the ejection of the first fluid from at least one of the one or more nozzle parts;
A diffuser section (210) that pressurizes a fluid in which the first fluid ejected from each of the one or more nozzle sections and the second fluid sucked from the suction section are mixed;
Forming one or more valve parts (214) that open and close the valve part flow path, forming a valve part flow path (215) connected to the upstream side of each nozzle part flow path of the one or more nozzle parts;
Each nozzle section flow path of the one or more nozzle sections includes a throttle section (204a) having a minimum flow path cross-sectional area in the nozzle section flow path,
Each of the one or more valve parts is connected to one valve part upstream flow path (244) through which the first fluid flows on the upstream side of the valve part,
Each valve part flow path of the one or more valve parts includes a minimum part (215a) in which the flow path cross-sectional area is minimum in the valve part flow path,
The flow path of the first fluid including the nozzle section flow path of one or more nozzle sections and the valve section flow path of one or more valve sections is a minimum section of one or more valve sections and one or more nozzle sections. Including a throttle upstream side channel (222) that is a channel between the throttle unit and
The average value of the pressures of the first fluid in the flow passage on the upstream side of the throttle portion during a period in which at least one of the one or more valve portions is in the open state is the critical pressure ratio of the first fluid and the valve portion It is smaller than the critical pressure determined based on the pressure of the first fluid in the upstream flow path.

  According to this, the average value of the pressure of the first fluid in the throttle upstream side flow path is smaller than the critical pressure. Thereby, as the simulation result of the present inventor to be described later, the valve opening per control cycle is compared with the case where the average value of the pressure of the first fluid in the throttle upstream side flow path is larger than the critical pressure. The linearity of the change in flow rate with respect to time can be improved.

The ejector of the invention according to claim 6 is:
A nozzle part (202) for forming a nozzle part flow path (204) through which the first fluid flows and ejecting the first fluid flowing through the nozzle part flow path;
A suction part (208) for sucking the second fluid by the ejection of the first fluid from the nozzle part;
A diffuser section (210) that pressurizes a fluid in which the first fluid ejected from the nozzle section and the second fluid sucked from the suction section are mixed; and
A valve part flow path (215) connected to the upstream side of the nozzle part flow path, and a valve part (214) for opening and closing the valve part flow path,
The nozzle section flow path includes a throttle section (204a) having a minimum flow path cross-sectional area in the nozzle section flow path,
The valve part flow path includes a minimum part (215a) in which the cross-sectional area of the valve part flow path is minimum,
The flow path of the first fluid including the nozzle part flow path and the valve part flow path includes a throttle part upstream side flow path (222) that is a flow path of the first fluid between the minimum part and the throttle part,
A critical value in which the average value of the pressure of the first fluid in the upstream flow path in the throttle portion during the valve opening period is determined based on the critical pressure ratio of the first fluid and the pressure on the inlet side of the minimum portion. Ejector smaller than pressure.

  According to this, the average value of the pressure of the first fluid in the throttle upstream side flow path is smaller than the critical pressure. Thereby, as the simulation result of the present inventor to be described later, the valve opening per control cycle is compared with the case where the average value of the pressure of the first fluid in the throttle upstream side flow path is larger than the critical pressure. The linearity of the change in flow rate with respect to time can be improved.

  Reference numerals in 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 figure which shows the structure of the fuel cell system in 1st Embodiment. It is sectional drawing of the ejector in FIG. It is an enlarged view of the valve part of the ejector of FIG. It is an enlarged view of the nozzle part of the ejector of FIG. In the ejector of the comparative example 1, it is a figure which shows the change of the flow volume of the fluid which flows in into a nozzle part from a valve part with respect to time passage when a valve part is controlled to open and close. It is a figure which shows the part of 1 control period among the flow volume waveforms shown in FIG. In the ejector of the comparative example 1, it is a figure which shows the change of the flow volume of the fluid which flows in into a nozzle part from a valve part with respect to time passage when a valve part is controlled to open and close. In the ejector of the comparative example 1, it is a figure which shows the change of the flow volume of the drive flow with respect to the length of the valve opening time per control period when changing the valve opening time of one control period, with the duty ratio fixed. . In the ejector of the comparative example 1, it is a figure which shows the change of the flow volume of the drive flow with respect to the length of the valve opening time per control period when changing Duty ratio, fixing the time length of a control period. In the ejector having the structure shown in FIG. 2, when the value of D1 / D2 is changed to an arbitrary value, the relationship between the elapsed time immediately after the valve opening and the pressure in the flow passage on the upstream side of the throttle portion is shown. It is a simulation result. It is a graph which shows the average value of the pressure during the valve opening state computed from the result of FIG. In the ejector having the structure shown in FIG. 2, when the value of D1 / D2 is changed to an arbitrary value, the relationship between the elapsed time immediately after the valve opening and the flow rate of the fluid in the upstream flow path of the throttle unit It is a simulation result which shows. In the ejector of 1st Embodiment, it is a figure which shows the change of the flow volume of the drive flow with respect to the length of the valve opening time per control period when changing the valve opening time of one control period, with the duty ratio fixed. is there. In the ejector of 1st Embodiment, it is a figure which shows the change of the flow volume of the drive flow with respect to the length of the valve opening time per control period when changing Duty ratio, fixing the time length of a control period. . It is sectional drawing of the ejector of 2nd Embodiment. It is sectional drawing of the ejector of 3rd Embodiment. It is a figure which shows the structure of the ejector-type refrigerating cycle of 4th Embodiment. It is a figure which shows the structure of the ejector of 5th Embodiment. It is a figure which shows the structure of the ejector of 6th Embodiment. It is a figure which shows the structure of the ejector of 7th Embodiment. It is a figure which shows the structure of the ejector of 7th Embodiment. It is a figure which shows the structure of the ejector of 8th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
As shown in FIG. 1, the fuel cell system 10 of the present embodiment includes a fuel cell 12, a fuel gas supply path 14, an offgas supply path 16, and an ejector 20.

  The fuel cell 12 generates electric energy by a chemical reaction between the fuel gas and the oxidant gas. In this embodiment, hydrogen gas is used as the fuel gas, and oxygen in the air is used as the oxidant gas. Electrical energy is generated by the electrochemical reaction between hydrogen and oxygen.

  The fuel gas supply path 14 guides the fuel gas to the fuel cell 12. The off gas supply path 16 joins the off gas discharged from the fuel cell 12 to the fuel gas supply path 14. The off gas includes an unreacted gas that has not been used for the chemical reaction in the fuel gas supplied to the fuel cell 12. The ejector 20 is provided at a junction of the off gas supply path 16 in the fuel gas supply path 14. The ejector 20 discharges fuel gas. Further, the ejector 20 sucks off gas and discharges the sucked off gas together with the fuel gas.

  As shown in FIG. 2, the ejector 20 includes a nozzle portion 202, a main body portion 206, and an on-off valve 212.

  The nozzle part 202 forms a nozzle part flow path 204 through which fuel gas flows. The nozzle part 202 ejects fuel gas flowing through the nozzle part flow path 204. The nozzle section flow path 204 includes a decreasing section 205 in which the flow path cross-sectional area decreases as it proceeds in the fuel gas flow direction. In the present embodiment, the entire nozzle part flow path 204 is the reduction part 205. Therefore, the nozzle section flow path 204 has a throttle section 204 a that has a minimum flow path cross-sectional area in the nozzle section flow path 204 at the downstream end of the nozzle section flow path 204. The fuel gas is a compressible fluid. The fuel gas corresponds to the first fluid.

  The main body portion 206 includes a suction portion 208 and a diffuser portion 210. The suction unit 208 sucks off gas from the off gas supply path 16 by the ejection of fuel gas from the nozzle unit 202. The suction part 208 forms a suction part flow path 209 through which off-gas flows. Off-gas is a compressible fluid. The off gas corresponds to the second fluid.

  The diffuser unit 210 raises the pressure of the mixed gas of the fuel gas ejected from the nozzle unit 202 and the off gas sucked from the suction unit 208. The diffuser unit 210 discharges the pressurized mixed gas. The diffuser part 210 forms a diffuser part flow path 211 in which a mixed gas flows. In the present embodiment, the diffuser unit 210 also serves as a mixing unit that mixes the fuel gas ejected from the nozzle unit 202 and the off-gas sucked from the suction unit 208. Note that the mixing unit and the diffuser unit 210 may be separated.

  In the present embodiment, the flow path shape of the ejector 20 is fixed except for the on-off valve 212. For this reason, in this embodiment, the ejector 20 does not have a movable part for changing a flow path shape. The shape of the flow path of the ejector 20 includes the shape of the nozzle section flow path 204, the shape of the diffuser section flow path 211, and the like. The flow path shape of the ejector 20 is fixed when the ejector 20 is used, the cross-sectional area of the nozzle part flow path 204, the angle of the inner wall surface of the nozzle part 202 that forms the nozzle part flow path 204, the nozzle part This means that the length of the flow path 204, the cross-sectional area of the diffuser section flow path 211, and the like are not changed and are constant.

  The on-off valve 212 opens and closes the flow path on the upstream side of the nozzle unit 202. The on-off valve 212 includes a valve unit 214 and a drive unit (not shown) that drives the valve unit 214. The valve part 214 has a valve part flow path 215 that is continuous with the nozzle part flow path 204 formed therein. The valve part 214 opens and closes this valve part flow path 215. The valve part 214 is connected to one valve part upstream flow path 244 shown in FIG. 1 through which fuel gas flows. The valve portion upstream side flow path 244 is a part of the fuel gas supply path 14.

  More specifically, the valve part 214 includes a valve body part 216, a valve body 218, and a valve seat 220. The valve body 216 is formed with an internal space serving as a flow path through which the fuel gas flows. The valve body 218 and the valve seat 220 open and close a flow path constituted by the internal space of the valve body 216. When the valve part 214 is in the open state, the fuel gas flows between the valve body 218 and the valve seat 220. Therefore, the internal space of the valve body 216 and the space between the valve body 218 and the valve seat 220 in the valve open state constitute the valve channel 215.

  The valve portion flow path 215 includes a minimum portion 215a in which the flow path cross-sectional area is minimum in the valve portion flow path 215 when the valve portion 214 is in the valve open state. In the present embodiment, as shown in FIG. 3, when the valve is open, a portion of the valve portion flow path 215 on the downstream side of the space between the valve body 218 and the valve seat 220 is the minimum portion 215 a. It has become. In addition, the space between the valve body 218 and the valve seat 220 in the valve part flow path 215 may be the minimum part 215a.

  The fuel gas flow path including the nozzle part flow path 204 and the valve part flow path 215 includes a throttle upstream side flow path 222 which is a fuel gas flow path between the minimum part 215a and the throttle part 204a. The throttle upstream side flow path 222 includes a downstream end of the minimum part 215a and an upstream end of the throttle 204a.

  Here, as shown in FIG. 3, the throttle diameter of the valve part 214 is set to D1. The throttle diameter D1 of the valve part 214 is the hydraulic diameter of the minimum part 215a. The hydraulic diameter is the diameter of a circular tube equivalent to the cross section of the flow path. The hydraulic diameter is expressed by 4 × (channel cross-sectional area) / (wetting edge length). The wet edge length is the length of the wall surface in the channel cross section. When the cross-sectional shape of the channel is a ring shape, the wet edge length is the sum of the wet edge length of the inner periphery of the ring and the wet edge length of the outer periphery of the ring.

  Further, as shown in FIG. 4, the aperture diameter of the nozzle portion 202 is set to D2. The throttle diameter D2 of the nozzle part 202 is the hydraulic diameter of the throttle part 204a.

  At this time, in this embodiment, the throttle diameter D1 of the valve portion 214 and the throttle diameter D2 of the nozzle portion 202 are set so as to satisfy the following expression (1).

0.95 ≦ D1 / D2 ≦ 1.2 (1)
As a result, the average value of the pressure of the fuel gas in the throttle upstream side flow path 222 during the valve portion 214 is in the open state is based on the critical pressure ratio of the fuel gas and the pressure on the inlet side of the minimum portion 215a. Becomes smaller than the critical pressure. The pressure on the inlet side of the minimum portion 215a is the pressure of the fuel gas in the valve portion upstream flow path 244.

Here, each of the critical pressure ratio and the critical pressure is the same as that defined by compressible fluid dynamics. The following literature is mentioned as a literature about compressible fluid dynamics.
Matsuo Kazuyasu, Compressible Fluid Dynamics Theory and Analysis of Internal Flow, 1st Edition, Rigakusha, Nov. 10, 1994.
The critical pressure ratio is the ratio of the pressure on the inlet side and the pressure on the outlet side of the minimum portion 215a when the flow velocity of the fluid passing through the minimum portion 215a reaches the speed of sound. The critical pressure ratio is the maximum value of the ratio of the pressure on the inlet side and the pressure on the outlet side of the minimum portion 215a when the fluid flow through the minimum portion 215a becomes a choke flow. When the ratio of the pressure on the inlet side and the pressure on the outlet side of the minimum portion 215a is smaller than the critical pressure ratio, the flow velocity of the fluid passing through the minimum portion 215a becomes the sonic velocity. The fluid flow at this time is a choke flow. In the flow, a state where the velocity at a certain point is equal to the speed of sound at that point is a critical state defined by compressible fluid dynamics. The critical pressure is the magnitude of the pressure on the outlet side of the minimum portion 215a when the flow velocity of the fluid passing through the minimum portion 215a is sonic, that is, when the fluid passing through the minimum portion 215a is in a critical state. Therefore, the critical pressure is determined based on the critical pressure ratio of the fuel gas and the pressure on the inlet side of the minimum portion 215a.

The critical pressure ratio is b, and the inlet-side pressure of the minimum portion 215a and P _0, the pressure when the pressure on the outlet side of the smallest portion 215a is the critical pressure and P ^*, the specific heat ratio of the fluid and gamma. At this time, the critical pressure ratio and the critical pressure are expressed by the following equations (2) and (3).

Ｐ^＊＝ｂ・Ｐ_０・・・（３）
図１に示すように、本実施形態の燃料電池システム１０では、燃料ガスが燃料電池１２に向けて燃料ガス供給経路１４を流れる。燃料電池１２は、供給された燃料ガスと供給された空気との化学反応により発電する。燃料電池１２から排出されたオフガスは、エジェクタ２０によってオフガス供給経路１６を流れて、燃料ガス供給経路１４に合流する。

P ^* = b · P ₀ (3)
As shown in FIG. 1, in the fuel cell system 10 of the present embodiment, the fuel gas flows through the fuel gas supply path 14 toward the fuel cell 12. The fuel cell 12 generates power by a chemical reaction between the supplied fuel gas and the supplied air. The off-gas discharged from the fuel cell 12 flows through the off-gas supply path 16 by the ejector 20 and joins the fuel gas supply path 14.

  At this time, in the ejector 20, fuel gas is ejected from the nozzle part 202 as indicated by arrows F1, F2, and F3 in FIG. Thereby, off-gas is sucked from the off-gas supply path 16 to the suction unit 208 as indicated by an arrow F4 in FIG. The fuel gas ejected from the nozzle part 202 and the off-gas sucked from the suction part 208 merge at the diffuser part 210 to become a mixed gas. As shown by an arrow F5 in FIG. 2, the mixed gas is discharged from the diffuser unit 210 to the fuel gas supply path 14.

  Here, as described above, the ejector 20 is a fluid pump including the nozzle unit 202, the suction unit 208, and the diffuser unit 210. The ejector 20 converts the kinetic energy of the driving flow that flows as a jet from the nozzle unit 202 into pressure energy. More specifically, the working fluid is sucked from the suction portion 208 by the pressure reduction and traction effect of the driving flow from the nozzle portion 202. An arrow F3 in FIG. 2 indicates the driving flow. An arrow F4 in FIG. 2 indicates the suction flow. When the working fluid is decelerated in the diffuser unit 210, the kinetic energy is converted into pressure energy, and the pressure energy increases.

  Like the ejector 20 of the present embodiment, an ejector having a fixed flow path shape does not have a movable part for changing the flow path shape. For this reason, in general, an ejector having a fixed flow path shape is superior in durability, reliability, and manufacturing cost as compared with a mechanical pump.

  The performance of the ejector 20 strongly depends on the magnitude of the kinetic energy of the driving flow and the flow path shape of the ejector 20. For this reason, the performance of the ejector can be changed by changing the kinetic energy of the driving flow or the flow path shape of the ejector.

  However, changing the flow path shape of the ejector gives a movable part. For this reason, changing the shape of the flow path of the ejector loses the feature of not having the movable portion of the ejector. Therefore, in many cases, the kinetic energy of the driving flow is changed in order to vary the performance of the ejector. This change in kinetic energy can be realized by changing the pressure or temperature on the inlet side of the throttle part of the nozzle part or changing the flow rate of the driving flow.

  In order to change the flow rate of the driving flow, there are methods such as changing the diameter of the throttle part of the nozzle part or intermittently opening and closing the flow path on the inlet side of the nozzle part. In the present application, attention is paid to a method of intermittently opening and closing the flow path on the inlet side of the latter nozzle portion 202. By adjusting the opening time of the flow path and the closing time of the flow path, the flow rate of the driving flow can be changed.

  Therefore, the fuel cell system 10 includes a control device 22. The control device 22 controls the opening and closing of the valve unit 214 so that the flow rate of the driving flow becomes a desired flow rate. In the opening / closing control of the valve unit 214, the valve opening state and the valve closing state of the valve unit 214 are alternately repeated. A combination of one valve opening state and one valve closing state is defined as one control cycle. The flow rate of the driving flow is changed by changing the length of one control cycle or the duty ratio. The duty ratio is a ratio of the time length of the valve opening state to the sum of the time length of the valve opening state and the time length of the valve closing state in one control cycle.

  In the opening / closing control of the valve portion 214 of the present embodiment, the valve portion 214 is switched between a fully open state and a valve closed state. However, the fully open state is the first valve open state, the opening between the fully open and fully closed is the second valve open state, the first valve open state, the second valve open state, The valve closing state may be switched.

  Next, the problem which the ejector 20 of this embodiment solves is demonstrated.

  In general, in the case of designing a fluid device including the valve unit 214 and the nozzle unit 202 on the premise of a steady flow, the throttle diameter D1 of the valve unit 214 is set sufficiently larger than the throttle diameter D2 of the nozzle unit 202. . This is for reducing the pressure loss at the valve portion 214 when the valve portion 214 is fully opened. The ejector 20 set in this way is called the ejector 20 of the comparative example 1.

  In the ejector 20 of the comparative example 1, the valve portion 214 is repeatedly opened and closed alternately. At this time, the flow rate of the fluid flow F2 in FIG. 2 changes with time as shown in FIGS. The fluid flow F <b> 2 is a fluid flow that flows into the nozzle unit 202 from the valve unit 214. The flow rate here is a mass flow rate. FIG. 5 shows a change in the flow rate of the fluid flow F2 with respect to the elapsed time in the ejector 20 of the comparative example 1. The elapsed time is an elapsed time from immediately after the valve portion 214 is opened. In FIG. 5, one control cycle is T1. The valve opening time is T2. The valve closing time is T3. FIG. 6 shows a portion of one control cycle in the flow rate waveform shown in FIG.

  As shown in FIG. 6, in the initial stage of valve opening, which is a period immediately after valve opening, the flow rate is the first flow rate Q1, which is a large flow rate. Thereafter, the flow rate decreases from the first flow rate Q1 to the second flow rate Q2 smaller than the first flow rate Q2. Thereafter, the flow rate becomes constant at the second flow rate Q2. Hereinafter, a portion where the flow rate is larger than the second flow rate Q2 in the flow rate waveform shown in FIG. 6 is referred to as an inrush flow rate portion.

  The reason why such a flow rate change has occurred is as follows. That is, immediately after the valve portion 214 is opened, the pressure ratio between the inlet side and the outlet side of the valve portion 214 is equal to or lower than the critical pressure ratio. This pressure ratio is the ratio of the pressure on the outlet side of the valve portion 214 to the pressure on the inlet side of the valve portion 214. For this reason, the fluid flow F2 is a choke (ie, sonic) flow. The first flow rate Q1 is a flow rate at the time of this choke flow.

  As time elapses immediately after the valve 214 is opened, the pressure on the outlet side of the valve 214 increases. The pressure on the outlet side of the valve unit 214 is the pressure of the throttle unit upstream channel 222. When the pressure on the outlet side of the valve portion 214 increases, the pressure ratio between the inlet side and the outlet side of the valve portion 214 becomes larger than the critical pressure. For this reason, the fluid flow F2 is not a choke flow, and the flow velocity decreases. The flow rate of the fluid flow F2 decreases from the first flow rate Q1 to the second flow rate Q2.

  Thereafter, the pressure ratio between the inlet side and the outlet side of the throttle portion 204a is equal to or lower than the critical pressure ratio. For this reason, the fluid flow F3 from the throttle portion 204a is a choke flow. The second flow rate Q2 is the flow rate of the fluid flow F2 during this choke flow. The pressure ratio between the inlet side and the outlet side of the throttle portion 204a is the ratio of the pressure on the outlet side of the throttle portion 204a to the pressure on the inlet side of the throttle portion 204a. The pressure on the inlet side of the throttle portion 204a is the same as the pressure on the outlet side of the valve portion 214.

  Here, the flow rate when the fluid flow F2 becomes a choke flow is determined by the throttle diameter D1 of the valve portion 214 and the state of the fluid on the inlet side of the valve portion 214 (ie, the temperature and pressure of the fluid). Similarly, the flow rate when the fluid flow F3 becomes a choke flow is determined by the throttle diameter D2 of the throttle portion 204a and the state of the fluid on the inlet side of the throttle portion 204a (that is, the temperature and pressure of the fluid). The throttle diameter D1 of the valve portion 214 is sufficiently larger than the throttle diameter D2 of the throttle portion 204a. For this reason, the first flow rate Q1 is larger than the second flow rate Q2. Therefore, an inrush flow rate portion is generated in the flow rate waveform shown in FIG.

  Incidentally, as one method of valve opening control of the valve unit 214, there is a method of shortening the valve opening time by fixing the duty ratio. This control method aims to suppress the pulsation of the driving flow by shortening the valve opening time without changing the flow rate of the driving flow by fixing the duty ratio. The flow rate of the driving flow is the same as the flow rate of the fluid flow F2 in FIG.

  However, when the time of one control cycle is halved without changing the duty ratio with respect to the valve opening control with the flow rate waveform shown in FIG. 5, the flow rate change with respect to the time of the drive flow is the flow rate shown in FIG. It becomes a waveform. In FIG. 7, one control cycle is 1/2 · T1. The valve opening time is 1/2 · T2. The valve closing time is 1/2 · T3. In the flow rate waveform shown in FIG. 7, the time during which the flow rate is constant at the second flow rate Q2 is shorter than the flow rate waveform shown in FIG. 5, but the flow rate and time of the inrush flow rate portion are not changed. Thus, the inrush flow rate portion of the flow rate waveform exists in the same shape in the flow rate waveform of one control cycle even if the length of time of the valve open state in one control cycle is shortened. Therefore, the shorter the time of one control cycle, the greater the influence of the inrush flow rate portion.

  For this reason, as shown in FIG. 8, when the duty ratio is constant and the valve opening time of one control cycle is shortened, the flow rate of the driving flow is changed. That is, the flow rate is not constant with respect to the valve opening time. FIG. 8 shows a change in the flow rate of the driving flow with respect to the length of the valve opening time per control cycle when the valve opening time of one control cycle is changed with the duty ratio fixed. The vertical axis in FIG. 8 represents the total area of the shaded regions in FIG. 6 in unit time. When a plurality of control periods are included in the unit time, the total of the areas of the flow rate waveforms of the plurality of control periods.

  Further, as another method for controlling the valve opening of the valve unit 214, there is a method of changing the duty ratio while fixing the time length of the control cycle. In this control method, the flow rate of the driving flow is adjusted by changing the duty ratio.

  However, as shown in FIG. 9, the flow rate of the driving flow does not change linearly with respect to the change of the duty ratio due to the influence of the inrush flow rate portion. FIG. 9 shows the change in the flow rate of the driving flow with respect to the length of the valve opening time per control cycle when the duty ratio is changed while the time length of the control cycle is fixed. The length of the valve opening time per control cycle on the horizontal axis can be converted into a duty ratio.

  Thus, when the throttle diameter D1 of the valve part 214 is set sufficiently larger than the throttle diameter D2 of the nozzle part 202, the ejector 20 is a straight line of the change in the flow rate of the driving flow with respect to the valve opening time per control cycle. It has the characteristic that the nature is low. In this case, in the fuel cell system 10, in order to accurately adjust the flow rate of the drive flow of the ejector 20, feedback control using a detection unit that detects the flow rate of the drive flow is required. In this feedback control, the valve opening time of the valve unit 214 is adjusted according to the flow rate of the driving flow detected by the detection unit. For this reason, a detection part is required for the fuel cell system 10. Furthermore, since the feedback control is performed, the configuration of the control device 22 becomes complicated.

  Next, the effect of the ejector 20 of this embodiment is demonstrated.

  In the present embodiment, the throttle diameter D1 of the valve portion 214 and the throttle diameter D2 of the nozzle portion 202 are set so as to satisfy the above formula (1).

  FIG. 10 is a simulation result showing the change over time in the pressure in the throttle upstream side flow path 222 when the value of D1 / D2 is 2.2 to 0.95 in the ejector shown in FIG. . The horizontal axis in FIG. 10 indicates the elapsed time in one control cycle when the valve unit 214 is controlled to open and close. FIG. 11 is a graph showing the average value of the pressure within the valve opening time in FIG. 10 when the value of D1 / D2 is a value of 2.2 to 0.95. FIG. 12 is a simulation result showing the change of the flow rate of the fluid flow F2 with respect to time when the value of D1 / D2 is 2.2 to 0.95. The horizontal axis of FIG. 12 indicates the elapsed time in one control cycle when the valve unit 214 is controlled to open and close.

  In these simulations, the value of D1 / D2 was changed without changing each of the pressure on the upstream side of the valve portion 214 and the pressure on the downstream side of the throttle portion 204a. Further, changing the value of D1 / D2 was performed by fixing the size of the throttle diameter D2 of the nozzle portion 202 and changing the throttle diameter D1 of the valve portion 214.

  When the values of D1 / D2 are values of 2.2 to 0.95, the pressure in the throttle upstream side flow path 222 changes as shown in FIG. 10 from immediately after the valve opening until the valve is closed. And the average value of the pressure within the valve opening time in FIG. 10 when the value of D1 / D2 is each value of 2.2-0.95 was as shown in FIG. As shown in FIG. 11, when the value of D1 / D2 is smaller than 1.2, the average value of pressure is smaller than the critical pressure.

  As shown in FIG. 12, when the value of D1 / D2 is smaller than 1.2, the inrush flow rate portion shown in FIG. 6 can be made smaller than when the value of D1 / D2 is 1.3 or more. it can. That is, when the value of D1 / D2 is smaller than 1.2, the flow rate can be made constant.

  Here, the flow rate waveform becomes the waveform shown in FIG. 6 because the flow from the minimum portion 215a is not maintained in a critical state. On the other hand, according to this embodiment, the average value of the pressure of the throttle upstream side flow path 222 is smaller than the critical pressure. For this reason, the flow from the minimum part 215a is maintained in the critical state or a state close to it during the period when the valve part 214 is in the valve open state. Therefore, it is considered that the flow rate from the minimum portion 215a approaches a constant value. The simulation result is a result when the volume of the throttle upstream side flow path 222 is a specific size. However, it is considered that a similar result can be obtained even when the volume of the throttle upstream side flow path 222 is not this specific size.

  In general, it is desirable that the error of the flow rate with respect to the target value is within 5%. In the system using the ejector 20, the present inventor estimated the error with respect to the target value of the driving flow when the valve portion 214 is controlled to open and close when the value of D1 / D2 is 1.2. As a result, the error could be suppressed within 5%. Therefore, when the value of D1 / D2 is 1.2 or less, the error can be suppressed within 5%.

  The reason why the value of D1 / D2 is set to 0.95 or more is as follows. Consider a case in which the value of D1 / D2 is decreased by fixing the size of the throttle diameter D2 of the nozzle portion 202 and decreasing the throttle diameter D1 of the valve portion 214. In this case, as the value of D1 / D2 decreases, the flow rate of the fluid flowing through the throttle upstream side flow path 222 decreases. In order to maintain the flow rate of the fluid flowing through the restricting portion upstream flow path 222, the restricting diameter D2 of the nozzle portion 202 must be increased. However, it is not preferable to increase the aperture diameter D2 of the nozzle portion 202. This is because the size of the ejector 20 increases the cost of the ejector 20. Therefore, in this embodiment, the value of D1 / D2 is set to 0.95 or more. Thereby, it can suppress that the aperture diameter D2 of the nozzle part 202 becomes large, and the enlargement of the ejector 20 can be suppressed.

  According to the present embodiment, as shown in FIG. 13, when the duty ratio is fixed and the valve opening time is changed, the ejector 20 can have a characteristic that the flow rate is almost constant. FIG. 13 shows the change in the flow rate of the drive flow with respect to the length of the valve opening time per control cycle when the valve opening time of one control cycle is changed with the duty ratio fixed in the ejector 20 of the present embodiment. Is shown.

  Furthermore, according to this embodiment, as shown in FIG. 14, when the time length of the control cycle is fixed and the duty ratio is changed, the flow rate becomes the duty ratio (that is, the length of the valve opening time). Thus, the ejector 20 can be given a characteristic of linearly changing with respect to the angle. FIG. 14 shows the change in the flow rate of the driving flow with respect to the length of the valve opening time per control cycle when the duty ratio is changed while the time length of the control cycle is fixed in the ejector 20 of the present embodiment. Show.

  In this way, the ejector 20 can have the characteristic that the linearity of the flow rate change with respect to the valve opening time per control cycle is high.

  For this reason, when adjusting the drive flow of the ejector 20 to the target flow rate, the control device 22 sets the valve opening time according to the target flow rate. That is, the control device 22 sets the time of one control cycle and the duty ratio according to the target flow rate. Thereby, the drive flow of the ejector 20 can be adjusted to the target flow rate.

  Therefore, in this embodiment, the feedback control of the control device 22 is not necessary. For this reason, the detection part which detects the flow volume of a drive flow becomes unnecessary. Furthermore, the configuration of the control device 22 is simplified. As a result, the production cost of the fuel cell system 10 to which the ejector 20 of the present embodiment is applied can be reduced.

(Second Embodiment)
As shown in FIG. 15, in the present embodiment, the shape of the flow path formed by the valve body portion 216 is different from that of the first embodiment. A part of the flow path formed by the valve body part 216 is an enlarged part 224. The enlarged portion 224 has a flow passage cross-sectional area that is larger than the portion 205 a where the flow passage cross-sectional area is maximum in the reduction portion 205. Accordingly, the throttle upstream side flow path 222 includes the enlarged portion 224 on the upstream side of the reducing portion 205.

The volume of the throttle upstream side flow path 222 is set to V. Let _{c be} the critical density of the fuel gas. Let _{c c be} the critical flow velocity of the fuel gas. Let A be the cross-sectional area of the flow path at the minimum portion 215a. Let τ be the valve opening time of the valve unit 214 within one control cycle. Immediately before the valve part 214 is switched from the closed state to the open state, the off-gas density at the inlet of the suction part 208 is set to ρ ₀ .

  At this time, the volume of the throttle upstream side channel 222 is set so as to satisfy the following formula (4).

なお、臨界密度は、臨界密度比と、弁部２１４の入口側での密度とによって定まる密度である。臨界密度と臨界密度比とのそれぞれは、圧縮性流体力学で定義されているものと同じである。臨界密度は、最小部２１５ａの出口側での流体が臨界状態であるときの最小部２１５ａの出口側での流体の密度である。

The critical density is a density determined by the critical density ratio and the density on the inlet side of the valve portion 214. Each of the critical density and the critical density ratio is the same as defined in compressible fluid dynamics. The critical density is the density of the fluid on the outlet side of the minimum portion 215a when the fluid on the outlet side of the minimum portion 215a is in a critical state.

The critical density ratio is d, the density of the fuel gas on the inlet side of the minimum portion 215a is ρ ₀ , the density when the state on the outlet side of the minimum portion 215a is the critical state is ρ ^*, and the specific heat ratio of the fluid Is γ. At this time, the critical density ratio and the critical density are expressed by the following equations (5) and (6).

ρ^＊＝ｄ・ρ_０・・・（６）
臨界流速は、圧縮性流体力学で定義されているものと同じである。臨界流速は、流体が臨界状態のときの流速である。臨界流速をｕ_ｃとし、比熱比をγとしたとき、臨界流速は次の式（７）で示される。

ρ ^* = d · ρ ₀ (6)
The critical flow velocity is the same as defined in compressible hydrodynamics. The critical flow rate is a flow rate when the fluid is in a critical state. The critical flow rate was u _c, when the ratio of specific heat was gamma, critical flow rate is expressed by the following equation (7).

式（７）中のＲは気体定数、Ｔ_０は最小部２１５ａの入口での流体の温度である。

In Equation (7), R is a gas constant, and T ₀ is the temperature of the fluid at the inlet of the minimum portion 215a.

  The above equation (4) is for the average value of the pressure in the throttle upstream side flow passage 222 during the valve opening period to be lower than the critical pressure so that the fluid state in the minimum portion 215a can maintain the critical state. The condition of the volume of the throttle upstream side flow path 222 is shown.

The above equation (4) is derived as follows. That is, it is assumed that the fluid does not flow out from the throttle upstream side flow path 222. During the valve open state, the fluid flows into the throttle upstream side flow path 222. A change in mass from when the valve-closed state is switched to the valve-open state at this time until the valve-closed state is switched is denoted by Δm. When the fluid state at the minimum portion 215a becomes a critical state, this change in mass is expressed by the following two equations (8) and (9).
Δm = ρ _c · u _c · A · τ (8)
Δm = (ρ _c −ρ ₀ ) · V (9)

  Expression (9) shows a change in mass depending on the density change of the fuel gas before and after the valve opening and the volume of the fuel gas. The maximum density after opening is the critical density of the fuel gas. In this embodiment, the density of the off gas measured at the inlet of the suction unit 208 is regarded as the density of the fuel gas before opening, that is, the density of the fuel gas downstream from the nozzle unit 202.

Expression (10) is derived from Expressions (8) and (9).
V = ρ _c · u _c · A · τ / (ρ _c −ρ ₀ ) (10)
Expression (10) indicates the volume of the throttle upstream side flow path 222 when the fluid state at the minimum portion 215a becomes a critical state.

Here, there is a one-to-one relationship between the pressure and density of the fluid in the throttle upstream side channel 222. As pressure increases, so does density. For this reason, the fact that the average pressure of the fluid in the throttle upstream side flow path 222 is lower than the critical pressure is equal to the density of the fluid in the partial upstream side flow path 222 being lower than the critical density. Further, when the mass is constant, there is a relationship that the density decreases as the volume increases. From this relationship, the volume may be increased in order to reduce the density of the fluid.
Therefore, Expression (4) is derived from Expression (10).

  Other configurations of the ejector 20 are the same as those in the first embodiment. The configuration of the fuel cell system 10 is the same as that of the first embodiment.

  According to the present embodiment, the volume of the throttle upstream side flow path 222 satisfies the formula (4). Thereby, similarly to 1st Embodiment, the average value of the pressure in the throttle part upstream flow path 222 becomes smaller than the critical pressure of a 1st fluid. Therefore, the present embodiment can provide the same effects as those of the first embodiment.

  In the present embodiment, the size of the throttle diameter D1 of the valve portion 214 may be larger than the throttle diameter D2 of the nozzle portion 202 such that the expression (1) described in the first embodiment is not satisfied. Moreover, the magnitude | size of the aperture diameter D1 of the valve part 214 may be a magnitude | size which satisfy | fills Formula (1) as described in 1st Embodiment.

(Third embodiment)
In the present embodiment, the valve portion 214 of the first embodiment is the first valve portion 214. In this embodiment, as shown in FIG. 16, the point from which the ejector 20 is provided with the 2nd valve part 230 differs from 1st Embodiment.

  When the pressure in the restrictor upstream flow path 222 exceeds a predetermined upper limit value, the second valve part 230 allows the fuel gas in the restrictor upstream flow path 222 to flow through the restrictor upstream without passing through the restrictor 204a. This is a pressure relief valve that discharges to the outside of the passage 222.

  An escape passage 232 is formed in the valve body 216 of the first valve 214. The escape channel 232 is connected to the throttle upstream side channel 222. The escape channel 232 is a channel for discharging a part of the fuel gas in the throttle upstream side channel 222 to the outside of the throttle upstream channel 222. The second valve unit 230 is connected to the escape passage 232. The second valve unit 230 opens and closes the escape passage 232.

  The second valve portion 230 is mechanically opened when the pressure in the throttle upstream side flow passage 222 exceeds a predetermined upper limit value. This upper limit value is set such that the average value of the pressure in the throttle upstream side flow path 222 during the period in which the valve 214 is in the open state is smaller than the critical pressure. As a result, the average value of the pressure in the throttle upstream side flow path 222 during the period in which the valve 214 is in the open state becomes smaller than the critical pressure.

  Therefore, also in this embodiment, the same effect as the first embodiment can be obtained. Note that the pressure sensor detects the pressure in the throttle upstream side channel 222. When the detection value of the pressure sensor exceeds a predetermined value, the second valve unit 230 may be opened.

  In the present embodiment, one second valve unit 230 is connected to the throttle upstream side flow path 222. However, two or more second valve parts 230 may be connected to the throttle upstream side flow path 222.

(Fourth embodiment)
As shown in FIG. 17, the ejector refrigeration cycle 30 of this embodiment includes a compressor 32, a radiator 34, an ejector 20, a gas-liquid separator 36, and an evaporator 38 as main components. ing. Each component is connected by refrigerant piping. Each component constitutes a vapor compression refrigeration cycle.

  The compressor 32 compresses and discharges the sucked refrigerant. The radiator 34 radiates the refrigerant discharged from the compressor 32. The radiator 34 is a heat exchanger that exchanges heat between the refrigerant of the refrigeration cycle and another heat exchange medium.

  The ejector 20 is the same as the ejector 20 of the first embodiment shown in FIG. The ejector 20 ejects the refrigerant that has flowed out of the radiator 34 from the nozzle portion 202. The ejector 20 sucks the refrigerant that has flowed out of the evaporator 38 from the suction unit 208. The ejector 20 discharges from the diffuser unit 210 a mixed refrigerant of the refrigerant sucked from the suction unit 208 and the refrigerant jetted from the nozzle unit 202. The refrigerant is a compressive fluid. The refrigerant flowing through the nozzle unit 202 corresponds to the first fluid. The refrigerant sucked from the suction part corresponds to the second fluid.

  The gas-liquid separator 36 is connected to the diffuser unit 210 of the ejector 20. The gas-liquid separator 36 separates the refrigerant flowing out of the diffuser unit 210 into a gas phase refrigerant and a liquid phase refrigerant. A refrigerant suction port of the compressor 32 is connected to the gas-phase refrigerant outlet side of the gas-liquid separator 36. The refrigerant inlet side of the evaporator 38 is connected to the liquid phase refrigerant outlet side of the gas-liquid separator 36. The evaporator 38 evaporates the refrigerant flowing toward the suction unit 208. The evaporator 38 is a heat exchanger that exchanges heat between the refrigerant of the refrigeration cycle and another heat exchange medium.

  In the ejector refrigeration cycle 30 configured as described above, the refrigerant discharged from the compressor 32 is radiated by the radiator 34. The refrigerant that has flowed out of the radiator 34 flows into the nozzle portion 202 of the ejector 20. The refrigerant that has flowed into the nozzle portion 202 is ejected from the nozzle portion 202 as indicated by arrows F1, F2, and F3 in FIG. At this time, in the nozzle unit 202, the refrigerant is decompressed and expanded by converting the pressure energy of the refrigerant into velocity energy. Further, the refrigerant flowing out of the evaporator 38 is sucked from the suction part 208 as indicated by an arrow F4 in FIG. The refrigerant ejected from the nozzle unit 202 and the refrigerant sucked from the suction unit 208 merge at the diffuser unit 210. The merged refrigerant is discharged from the diffuser unit 210 as indicated by an arrow F5 in FIG. At this time, in the diffuser unit 210, the refrigerant is boosted by converting the velocity energy of the refrigerant into pressure energy by expanding the cross-sectional area of the flow path.

  The refrigerant discharged from the diffuser unit 210 is separated into a gas phase refrigerant and a liquid phase refrigerant by the gas-liquid separator 36. The liquid phase refrigerant that has flowed out of the gas-liquid separator 36 evaporates in the evaporator 38 and then flows out of the evaporator 38. The gas-phase refrigerant that has flowed out of the gas-liquid separator 36 is sucked into the compressor 32.

  Also in the ejector refrigeration cycle 30 of the present embodiment, the same ejector 20 as in the first embodiment is used. For this reason, the effect similar to 1st Embodiment is acquired.

(Fifth embodiment)
As shown in FIG. 18, in this embodiment, the valve part 214 and the nozzle part 202 are connected via the intermediate flow path 240. The intermediate flow path 240 is a flow path between the valve part 214 and the nozzle part 202. The intermediate flow path 240 is formed by a pipe configured separately from both the valve portion 214 and the nozzle portion 202.

  The fuel gas flow path including the nozzle part flow path 204 of the nozzle part 202, the intermediate flow path 240, and the valve part flow path 215 of the valve part 214 is a fuel gas flow path between the minimum part 215a and the throttle part 204a. A certain throttle part upstream side flow path 222 is included.

  Other configurations of the ejector 20 are the same as those in the first embodiment. Therefore, also in this embodiment, the same effect as the first embodiment can be obtained. In each of the second to fourth embodiments, the configuration of this embodiment may be adopted.

(Sixth embodiment)
As shown in FIG. 19, in this embodiment, the ejector 20 includes two valve portions 214A and 214B. The two valve portions 214A and 214B are connected in parallel on the upstream side of the nozzle portion 202. Each configuration of the two valve portions 214A and 214B is the same as that of the valve portion 214 of the first embodiment.

  The upstream sides of the two valve portions 214 </ b> A and 214 </ b> B are connected to a single valve portion upstream flow path 244 via a branch portion 242. For this reason, the fuel gas which flows through the valve part upstream flow path 244 shown by the arrow F <b> 1 branches at the branch part 242. Each of the branched fuel gas flows into each of the two valve portions 214A and 214B.

  The downstream sides of the two valve portions 214 </ b> A and 214 </ b> B are connected to the nozzle portion 202 via the merging portion 246. Therefore, the fuel gas flowing out from each of the two valve portions 214A and 214B joins at the joining portion 246 and then flows into the nozzle portion 202 as indicated by an arrow F2.

  Each of the two valve portions 214A and 214B is opened and closed so that the valve opening period is the same or the valve opening period is shifted. In other words, each of the two valve portions 214A and 214B is controlled to open and close so that at least a part of the valve opening period overlaps.

  In the present embodiment, the ejector 20 includes a throttle upstream side flow path 222A that is a fuel gas flow path between the minimum part 215a of each of the two valve parts 214A and 214B and the throttle part 204a.

  A first hydraulic diameter that is a hydraulic diameter corresponding to the total value of the flow path cross-sectional areas of the minimum portions 215a of the two valve portions 214A and 214B is defined as D1. When the second hydraulic diameter, which is the hydraulic diameter of the throttle portion 204a, is D2, the first hydraulic diameter and the second hydraulic diameter satisfy Expression (1). In other words, the throttle diameter of the minimum part 215a and the throttle diameter of the throttle part 204a of each of the two valve parts 214A and 214B are set so as to satisfy Expression (1).

0.95 ≦ D1 / D2 ≦ 1.2 (1)
Thus, the average value of the pressure of the fuel gas in the throttle upstream side flow path 222 during a period in which at least one of the two valve portions 214A and 214B is in the open state is the fuel gas critical pressure ratio. It becomes smaller than the critical pressure determined based on the pressure of the fuel gas in the upstream flow path 244 of the valve portion. For this reason, also in this embodiment, the effect similar to 1st Embodiment is acquired.

  In the present embodiment, as in the second embodiment, the volume of the throttle upstream side flow path 222 may be set to satisfy Expression (4). Accordingly, the ejector 20 may be configured such that the average value of the pressure of the fuel gas in the throttle upstream side flow passage 222 is smaller than the critical pressure.

In this case, A in Formula (4) is the total value of the flow path cross-sectional areas of the minimum parts 215a of the two valve parts 214A and 214B. Ρ _c in the equation (4) is the critical density of the first fluid determined based on the critical density ratio of the fuel gas and the density of the fuel gas in the valve portion upstream side flow path 244. In Expression (4), τ represents one control cycle that is a combination of one valve opening state and one valve closing state of the respective valve portions when the two valve portions 214A and 214B are simultaneously opened and closed. Is the valve opening time within one control cycle. Ρ ₀ in the equation (4) is an inlet of the suction unit 208 immediately before each of the two valve units 214A and 214B is opened and closed at the same time when the respective valve units are switched from the closed state to the open state. The off-gas density.

  In the present embodiment, the ejector 20 may include one or more second valve portions 230 as in the third embodiment. Thereby, the average value of the pressure of the fuel gas in the throttle upstream side flow path 222 may be smaller than the critical pressure.

  In the present embodiment, the two valve portions 214A and 214B are connected in parallel on the upstream side of the nozzle portion 202. However, three or more valve parts may be connected in parallel on the upstream side of the nozzle part 202. In this case, what is necessary is just to read two valve part 214A, 214B as three or more valve parts in description of this embodiment.

(Seventh embodiment)
As shown in FIG. 20, in this embodiment, the ejector 20 includes two nozzle portions 202A and 202B. The two nozzle portions 202A and 202B are connected in parallel on the downstream side of the one valve portion 214. The configuration of each of the two nozzle portions 202A and 202B is the same as that of the nozzle portion 202 of the first embodiment.

  The upstream sides of the two nozzle portions 202 </ b> A and 202 </ b> B are connected to the downstream side of the one valve portion 214 via the branch portion 250. The upstream side of one valve portion 214 is connected to one valve portion upstream flow path 244. For this reason, the fuel gas flows in the order of the valve portion upstream flow path 244 and the valve portion 214 as indicated by an arrow F1 in FIG. The fuel gas flowing out from the valve part 214 branches at the branch part 250. Each branched fuel gas flows into each of the two nozzle portions 202A and 202B as indicated by arrows F2a and F2b in FIG. Accordingly, the total flow rate of the fuel gas flowing into the two nozzle portions 202A and 202B is the same as the flow rate of the fuel gas flowing into the nozzle portion 202 of the first embodiment.

  As shown in FIG. 21, the two nozzle portions 202 </ b> A and 202 </ b> B are provided for one main body portion 206. As indicated by arrows F3a and F3b in FIG. 21, the fuel gas ejected from each of the two nozzle portions 202A and 202B flows through the diffuser portion flow path 211 of one diffuser portion 210. As the fuel gas is ejected from at least one of the two nozzle portions 202A and 202B, off-gas is sucked from the suction portion 208 as indicated by an arrow F4 in FIG. The fuel gas ejected from at least one of the two nozzle portions 202A and 202B and the off-gas sucked from the suction portion 208 merge at the diffuser portion 210 to become a mixed gas. The mixed gas is discharged from the diffuser section 210 as indicated by an arrow F5 in FIG.

  In the present embodiment, as shown in FIG. 20, the ejector 20 includes a throttle part upstream side flow path 222 </ b> B that is a fuel gas flow path between the minimum part 215 a and the throttle parts 204 a of the two nozzle parts 202 </ b> A and 202 </ b> B. Have The throttle part upstream side flow path 222B of the present embodiment includes a flow path between the minimum part 215a and the branch part 250, a flow path between the branch part 250 and the throttle part 204a of one nozzle part 202A, and a branch. And a flow path between the portion 250 and the throttle portion 204a of the other nozzle portion 202B.

  And let the 1st hydraulic diameter which is the hydraulic diameter of the minimum part 215a be D1. A second hydraulic diameter, which is a hydraulic diameter corresponding to the total value of the channel cross-sectional areas of the throttle portions 204a of the two nozzle portions 202A and 202B, is D2. At this time, the first hydraulic diameter and the second hydraulic diameter satisfy Expression (1). In other words, the aperture diameter of the minimum portion 215a and the aperture diameters of the aperture portions 204a of the two nozzle portions 202A and 202B are set so as to satisfy Expression (1).

0.95 ≦ D1 / D2 ≦ 1.2 (1)
As a result, the average value of the pressure of the fuel gas in the throttle upstream side flow path 222 during the period in which the valve part 214 is in the open state is the critical pressure ratio of the fuel gas and the fuel in the valve part upstream side flow path 244. It becomes smaller than the critical pressure determined based on the pressure of the gas. For this reason, also in this embodiment, the effect similar to 1st Embodiment is acquired.

  In the present embodiment, as in the second embodiment, the volume of the throttle upstream side flow path 222 may be set to satisfy Expression (4). Thereby, the average value of the pressure of the fuel gas in the throttle upstream side flow path 222 may be smaller than the critical pressure.

  In the present embodiment, the ejector 20 may include one or more second valve portions 230 as in the third embodiment. Thereby, the average value of the pressure of the fuel gas in the throttle upstream side flow path 222 may be smaller than the critical pressure.

  In the present embodiment, two nozzle portions 202A and 202B are connected in parallel on the downstream side of one valve portion 214. However, three or more nozzle portions may be connected in parallel on the downstream side of one valve portion 214. In this case, what is necessary is just to read two nozzle part 202A, 202B as three or more nozzle parts in description of this embodiment.

(Eighth embodiment)
As shown in FIG. 22, the ejector 20 includes two valve portions 214A and 214B as in the sixth embodiment. Further, as in the seventh embodiment, the ejector 20 includes two nozzle portions 202A and 202B.

  In the present embodiment, as shown in FIG. 22, the ejector 20 is a fuel gas flow path between the minimum portion 215a of the two valve portions 214A and 214B and the throttle portion 204a of the two nozzle portions 202A and 202B. A certain throttle upstream side flow path 222C is provided. The restrictor upstream flow path 222C of the present embodiment includes a flow path between the minimum part 215a of one valve part 214A and the merging part 246 and a minimum part 215a of the other valve part 214B and the merging part 246. , The flow path between the merging portion 246 and the branch portion 250, the flow path between the branch portion 250 and the narrowed portion 204a of the one nozzle portion 202A, and the branch portion 250 and the other nozzle portion 202B. And a flow path between the throttle part 204a.

  A first hydraulic diameter that is a hydraulic diameter corresponding to the total value of the flow path cross-sectional areas of the minimum portions 215a of the two valve portions 214A and 214B is defined as D1. A second hydraulic diameter, which is a hydraulic diameter corresponding to the total value of the channel cross-sectional areas of the throttle portions 204a of the two nozzle portions 202A and 202B, is D2. At this time, the first hydraulic diameter and the second hydraulic diameter satisfy Expression (1). In other words, the throttle diameters of the minimum parts 215a of the two valve parts 214A and 214B and the throttle diameters of the throttle parts 204a of the two nozzle parts 202A and 202B are set so as to satisfy the expression (1). ing.

0.95 ≦ D1 / D2 ≦ 1.2 (1)
Thus, the average value of the pressure of the fuel gas in the throttle upstream side flow path 222 during a period in which at least one of the two valve portions 214A and 214B is in the open state is the fuel gas critical pressure ratio. It becomes smaller than the critical pressure determined based on the pressure of the fuel gas in the upstream flow path 244 of the valve portion. For this reason, also in this embodiment, the effect similar to 1st Embodiment is acquired.

  In this embodiment as well, the volume of the throttle upstream side flow passage 222 may be set so as to satisfy Expression (4) as in the second embodiment. Thereby, the average value of the pressure of the fuel gas in the throttle upstream side flow path 222 may be smaller than the critical pressure. The explanation of each symbol in the formula (4) at this time is the same as the explanation in the sixth embodiment.

  Also in this embodiment, the ejector 20 may include one or more second valve portions 230 as in the third embodiment. Thereby, the average value of the pressure of the fuel gas in the throttle upstream side flow path 222 may be smaller than the critical pressure.

  Also in this embodiment, three or more valve portions may be connected in parallel. Three or more nozzle portions may be connected in parallel.

  (Other embodiments)

  (1) In 1st-3rd embodiment, the nozzle part 202 and the valve part main-body part 216 are comprised as a different body. However, the nozzle part 202 and the valve part main-body part 216 may be comprised as an integrally molded product.

  (2) In each of the embodiments described above, the nozzle section flow path 204 has a throttle section 204 a at the downstream end of the nozzle section flow path 204. However, the nozzle section flow path 204 may have a throttle section 204 a on the upstream side of the downstream end of the nozzle section flow path 204.

  (3) In 2nd Embodiment, a part of flow path which the valve part main-body part 216 forms becomes the enlarged part 224. FIG. However, a part of the flow path formed by the nozzle part 202 may be the enlarged part 224. Even in this case, the throttle upstream side flow path 222 has an enlarged portion 224 on the upstream side of the reducing portion 205.

  (4) In the second embodiment, the throttle upstream side flow passage 222 has an enlarged portion 224 on the upstream side of the reducing portion 205. However, the throttle upstream side channel 222 may not have the enlarged portion 224. The length of the throttle upstream side channel 222 may be set so that the volume of the throttle upstream side channel 222 satisfies the equation (4). For example, the length of the intermediate flow path 240 may be set so that the volume of the throttle upstream flow path 222 satisfies Expression (4).

  (5) In the first to third embodiments, the first fluid ejected from the nozzle unit 202 is a fuel gas. In 4th Embodiment, the 1st fluid ejected from the nozzle part 202 is a refrigerant | coolant of a refrigerating cycle. However, the first fluid ejected from the nozzle unit 202 may be another compressive fluid.

  (6) The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope described in the claims, and includes various modifications and modifications within the equivalent range. 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, it is needless to say that elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Yes. 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 each of the above embodiments, when referring to the material, shape, positional relationship, etc. of the constituent elements, etc., unless otherwise specified, or in principle limited to a specific material, shape, positional relationship, etc. The material, shape, positional relationship, etc. are not limited.

(Summary)
According to the first aspect shown in part or all of the above embodiments, the ejector includes one or more nozzle parts, a suction part, a diffuser part, and one or more valve parts. The average value of the pressures of the first fluid in the flow passage on the upstream side of the throttle portion during a period in which at least one of the one or more valve portions is in the open state is the critical pressure ratio of the first fluid and the valve portion It is smaller than the critical pressure determined based on the pressure of the first fluid in the upstream flow path.

  Further, according to the second aspect, the first hydraulic diameter corresponding to the total value of the channel cross-sectional areas of the minimum parts of the one or more valve parts is D1, and the flow of the throttle parts of the one or more nozzle parts is The second hydraulic diameter corresponding to the total value of the road cross-sectional area is defined as D2. At this time, the first hydraulic diameter and the second hydraulic diameter satisfy the following formula (1).

0.95 ≦ D1 / D2 ≦ 1.2 (1)
According to this, by making D1 / D2 1.2 or less, the average value of the pressure of the first fluid in the throttle upstream side flow path can be made smaller than the critical pressure. Thus, the configuration of the second aspect can be adopted as a specific configuration for realizing the configuration of the first aspect.

  Furthermore, it can suppress that a nozzle part becomes large because D1 / D2 shall be 0.95 or more. Therefore, the enlargement of the ejector can be suppressed.

Further, according to the third aspect, the volume of the flow path on the upstream side of the throttle portion is V. Let _c be a critical density determined based on the critical density ratio of the first fluid and the density of the first fluid in the upstream flow path of the valve section. Let _{c c be} the critical flow velocity of the first fluid. Let A be the total value of the channel cross-sectional areas of the minimum part of one or more valve parts. Valve opening within one control cycle when a combination of one valve opening state and one valve closing state of the valve portions when one or more valve portions are simultaneously opened and closed is defined as one control cycle Let time be τ. Let ρ ₀ be the density of the second fluid at the inlet of the suction portion when the one or more valve portions are simultaneously opened and closed immediately before the valve portions are switched from the closed state to the open state. At this time, the volume of the flow path on the upstream side of the throttle portion satisfies the following formula (4).

これによれば、式（４）を満たすように、絞り部上流側流路の容積が設定されている。これにより、絞り部上流側流路内の第１流体の圧力の平均値を臨界圧力よりも小さくすることができる。このように、第１の観点の構成を実現するための具体的な構成として、第３の観点の構成を採用することができる。

According to this, the capacity | capacitance of the throttle part upstream flow path is set so that Formula (4) may be satisfy | filled. Thereby, the average value of the pressure of the 1st fluid in a throttle part upstream channel can be made smaller than a critical pressure. As described above, the configuration according to the third aspect can be adopted as a specific configuration for realizing the configuration according to the first aspect.

  Moreover, according to the 4th viewpoint, a nozzle part flow path contains the reduction | decrease part from which a flow-path cross-sectional area reduces gradually as it progresses in the flow direction of a 1st fluid. The throttle upstream side flow path includes an enlarged portion whose flow path cross-sectional area is larger than a portion where the flow path cross-sectional area is maximized in the reduced portion on the upstream side of the reduced portion. In the third aspect, specifically, the configuration of the fourth aspect can be adopted.

  Moreover, according to the 5th viewpoint, one or more valve parts are one or more 1st valve parts. When the pressure in the upstream of the throttle unit exceeds a predetermined upper limit, the first fluid in the upstream channel of the throttle unit flows outside the throttle upstream channel without passing through the throttle unit of one or more nozzle units. And one or more second valve parts for discharging to the tank.

  According to this, since the average value of the pressure of the 1st fluid in a throttle part upstream flow path becomes smaller than a critical pressure, an ejector is provided with one or more 2nd valve parts. The predetermined upper limit value is set so that the average value of the pressure of the first fluid in the restrictor upstream flow path is smaller than the critical pressure. Thereby, the average value of the pressure of the 1st fluid in a throttle part upstream channel can be made smaller than a critical pressure. As described above, the configuration according to the fifth aspect can be adopted as a specific configuration for realizing the configuration according to the first aspect.

  According to the sixth aspect, the ejector includes a nozzle portion, a suction portion, a diffuser portion, and a valve portion. The critical value that the average value of the pressure of the first fluid in the flow path on the upstream side of the throttle portion during the period in which the valve portion is open is determined based on the critical pressure ratio of the first fluid and the pressure on the inlet side of the minimum portion Less than pressure.

  According to the seventh aspect, the ejector refrigeration cycle includes any one of the ejectors according to the first to sixth aspects. The ejectors according to the first to sixth aspects can be used in the ejector refrigeration cycle.

  According to the eighth aspect, the fuel cell system includes any one ejector of the first to sixth aspects. The ejectors according to the first to sixth aspects can be used in a fuel cell system.

20 Ejector 202 Nozzle part 204 Nozzle part flow path 204a Restriction part 208 Suction part 210 Diffuser part 214 Valve part 215a Minimum part 222 Restriction part upstream flow path

Claims (8)

An ejector,
One or more nozzle parts (202) for forming a nozzle part flow path (204) through which the first fluid flows, and ejecting the first fluid flowing through the nozzle part flow path;
A suction part (208) for sucking the second fluid by the ejection of the first fluid from at least one nozzle part of the one or more nozzle parts;
A diffuser part (210) for increasing the pressure of a fluid in which the first fluid ejected from each of the one or more nozzle parts and the second fluid sucked from the suction part are mixed;
One or more valve parts (214) that open and close the valve part flow path by forming a valve part flow path (215) connected to the upstream side of the nozzle part flow path of each of the one or more nozzle parts. Prepared,
Each nozzle section flow path of the one or more nozzle sections includes a throttle section (204a) having a minimum flow path cross-sectional area in the nozzle section flow path,
Each of the one or more valve parts is connected to one valve part upstream flow path (244) through which the first fluid flows on the upstream side of the valve part,
Each of the valve part flow paths of the one or more valve parts includes a minimum part (215a) in which the flow path cross-sectional area is minimum in the valve part flow path,
The flow path of the first fluid including the nozzle part flow path of the one or more nozzle parts and the valve part flow path of the one or more valve parts is the minimum part of the one or more valve parts. A throttle part upstream side flow path (222) which is a flow path between the throttle part and the throttle part of the one or more nozzle parts,
An average value of the pressures of the first fluid in the flow path on the upstream side of the throttle portion during a period in which at least one of the one or more valve portions is in a valve open state is a critical pressure ratio of the first fluid. And an ejector that is smaller than a critical pressure determined based on the pressure of the first fluid in the upstream flow path of the valve unit. The first hydraulic diameter corresponding to the total value of the cross-sectional area of the minimum part of the one or more valve parts is D1, and the total value of the cross-sectional area of the throttle part of the one or more nozzle parts When the second hydraulic diameter corresponding to is D2,
The ejector according to claim 1, wherein the first hydraulic diameter and the second hydraulic diameter satisfy the following expression (1).
0.95 ≦ D1 / D2 ≦ 1.2 (1) The volume of the flow path on the upstream side of the throttle is V,
A critical density determined based on the critical density ratio of the first fluid and the density of the first fluid in the upstream flow path of the valve unit is ρ _c ,
The critical flow rate of the first fluid and u _c,
The total value of the cross-sectional area of the minimum part of the one or more valve parts is A,
Opening within one control cycle when a combination of one valve opening state and one valve closing state of the valve portions when each of the one or more valve portions is opened and closed simultaneously is one control cycle Let the valve time be τ,
The density of the second fluid at the inlet of the suction part when the one or more valve parts are simultaneously opened and closed immediately before the valve parts are switched from the closed state to the open state is represented by ρ ₀ . When
The ejector according to claim 1, wherein the volume of the flow path on the upstream side of the throttle portion satisfies the following formula (4).

The nozzle part flow path includes a decreasing part (205) in which the flow path cross-sectional area gradually decreases as it proceeds in the flow direction of the first fluid,
The expansion portion (224) in which the flow passage cross-sectional area is larger than the portion (205a) in which the flow passage cross-sectional area is maximum in the reduction portion, on the upstream side of the reduction portion. The ejector according to claim 3, comprising: The one or more valve portions are one or more first valve portions;
When the pressure in the throttle upstream side flow path exceeds a predetermined upper limit value, the throttle part upstream of the first fluid in the throttle upstream path is not passed through the throttle part of the one or more nozzle parts. The ejector according to claim 1, further comprising one or more second valve portions (230) that discharge to the outside of the upstream flow path. An ejector,
A nozzle part (202) for forming a nozzle part flow path (204) through which the first fluid flows, and ejecting the first fluid flowing through the nozzle part flow path;
A suction part (208) for sucking the second fluid by the ejection of the first fluid from the nozzle part;
A diffuser section (210) that pressurizes a fluid in which the first fluid ejected from the nozzle section and the second fluid sucked from the suction section are mixed; and
Forming a valve part flow path (215) continuous with the upstream side of the nozzle part flow path, and a valve part (214) for opening and closing the valve part flow path,
The nozzle section flow path includes a throttle section (204a) having a minimum flow path cross-sectional area in the nozzle section flow path,
The valve portion flow path includes a minimum portion (215a) where the flow path cross-sectional area is minimum in the valve portion flow path,
The flow path of the first fluid including the nozzle section flow path and the valve section flow path is a throttle upstream side flow path that is a flow path of the first fluid between the minimum portion and the throttle section ( 222),
The average value of the pressure of the first fluid in the upstream side flow passage in the throttle portion during the period in which the valve portion is open is the critical pressure ratio of the first fluid and the pressure on the inlet side of the minimum portion. The ejector is smaller than the critical pressure determined based on   An ejector-type refrigeration cycle comprising the ejector according to claim 1.   A fuel cell system comprising the ejector according to any one of claims 1 to 6.

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