KR20230014844A - Jet pumps and nozzle mechanisms for jet pumps - Google Patents

Abstract

The present invention relates to a nozzle mechanism for a jet pump, wherein the nozzle mechanism includes a driving nozzle and a first suction nozzle, the first suction nozzle is disposed radially outside the driving nozzle, and the nozzle mechanism is driven. Fluid flow through the nozzle is adapted to drive the fluid through the first suction nozzle. The present invention relates to a jet pump including such a nozzle mechanism.

Description

Jet pumps and nozzle mechanisms for jet pumps

The present invention relates to a nozzle mechanism for a jet pump, wherein the nozzle mechanism includes a driving nozzle and a first suction nozzle, the first suction nozzle is disposed radially outside the driving nozzle, and the nozzle mechanism comprises a driving nozzle. The fluid flow through is designed to drive the fluid flow through the first suction nozzle. The invention also relates to a jet pump comprising a corresponding nozzle mechanism.

A jet pump is used to create a secondary fluid flow over a primary drive fluid flow. The primary drive fluid is accelerated, for example by a pump, and guided into contact with the secondary fluid. The velocity and pressure gradient between the two fluids causes the second fluid to be accelerated by the first fluid flow. Thus in the jet pump the second fluid flow is driven by the first fluid flow.

Jet pumps can be designed as single-stage or multi-stage jet pumps comprising multiple pump stages and nozzles. The main disadvantage of jet pumps is their low efficiency due to the mixing of the high-velocity jets of the primary drive fluid with the nearly stagnant secondary fluid.

Accordingly, it is an object of the present invention to provide improved jet pumps and improved jet pump nozzle structures that exhibit superior efficiency compared to known jet pumps and jet pump nozzle structures.

The object of the present invention is achieved by a nozzle device according to claim 1 and a jet pump according to claim 10, said jet pump comprising at least one such nozzle device. Advantageous embodiments of the invention are the subject of the dependent claims.

According to the present invention, there is provided a nozzle mechanism for a jet pump, the nozzle mechanism including a driving nozzle and a first suction nozzle, the first suction nozzle being arranged radially outside the driving nozzle, the nozzle mechanism comprising: The fluid flow through the drive nozzle is designed to drive the fluid flow through the first suction nozzle. In a simple embodiment, the drive nozzle outlet may be located sufficiently close to the first suction nozzle outlet such that the low pressure and high velocity fluid flow of the drive nozzle can interact with the fluid of the first suction nozzle.

The first suction nozzle may be positioned such that the shear stress at the interface between the jet and the suction mass or the fluid flow through the drive nozzle and the fluid flow through the first or further suction nozzle is reduced. This is related to the fact that the shear stress defined above is the product of the fluid viscosity and the velocity gradient. The latter can be very large in jet pumps known in the art. High shear stresses generate turbulence, which rather leads to dissipation of primary energy, which is the reason for the low efficiency of known jet pumps. The jet pump and nozzle arrangement of the present invention provides improved jet pump efficiency because shear stress is reduced when mixing of two or more mass flows or fluid flows is induced.

In a preferred embodiment of the invention, the nozzle mechanism can be designed such that the first suction nozzles are concentrically arranged around the drive nozzle and/or the first suction nozzles comprise an axisymmetric volume, such as an annular volume. The driving nozzle and/or the first suction nozzle may in particular comprise a nozzle wall section characterized by rotational symmetry around a central axis of one or both of the nozzles.

In another preferred embodiment of the present invention, the nozzle mechanism may be designed such that the first mixing tube is provided downstream of the drive nozzle and the first suction nozzle. The first mixing tube may be connected to an outer wall of the first suction nozzle. In particular, outer walls of the first mixing tube and the first suction nozzle may be integrally formed. The first mixing tube, the driving nozzle and the first suction nozzle may be arranged coaxially with each other.

In a particularly preferred embodiment of the present invention, the nozzle mechanism may be designed to include a first diffuser stage in which the first mixing tube is at the downstream end of the first mixing tube. The first diffuser stage may be characterized by a larger cross-sectional area than a section of the first mixing tube located further upstream of the first diffuser stage. The first diffuser stage of the first mixing tube may be arranged concentrically with other parts of the first mixing tube and/or the drive nozzle and/or the first suction nozzle.

In another particularly preferred embodiment of the present invention, the nozzle arrangement may be designed such that the second suction nozzle is arranged downstream of the first mixing tube, wherein the nozzle arrangement is such that the fluid flow through the first mixing tube is directed to the second suction tube. It is designed to drive fluid through the nozzle, and/or the second suction nozzle is disposed concentrically around the first mixing tube and/or the second suction nozzle comprises an axisymmetric volume. The design and function of the second suction nozzle may include the same features as described for the first suction nozzle, where applicable.

In particular, the second suction nozzle may be located sufficiently close to the outlet of the first mixing tube so that the low pressure and high velocity fluid flow in the first mixing tube can interact with the fluid in the second suction nozzle. The second suction nozzle may be positioned such that the shear stress at the interface between the jet and the suction mass or fluid flow through the first mixing tube and through the second suction nozzle is reduced.

In a particularly preferred embodiment of the present invention, the nozzle mechanism may be designed such that a second mixing tube is provided downstream of the first mixing tube and the second suction nozzle. The second mixing tube may be connected to an outer wall of the second suction nozzle. In particular, outer walls of the second mixing tube and the second suction nozzle may be integrally formed. The second mixing tube, the first mixing tube, the driving nozzle and/or the first and second suction nozzles may be disposed coaxially with each other.

In a particularly preferred embodiment of the present invention, the nozzle mechanism may be designed to include a second diffuser stage in which the second mixing tube is at the downstream end of the second mixing tube. The second diffuser stage may be characterized by a larger cross-sectional area than the section of the second mixing tube located further upstream of the second diffuser stage. The second diffuser stage may be arranged concentrically with the second mixing tube and/or drive nozzle and/or other parts of the first and/or second suction nozzle.

In a particularly preferred embodiment of the present invention, the nozzle mechanism may be designed such that a first fluid flows through the actuating nozzle and a second fluid flows through the first and/or second suction nozzles, wherein the first and second fluids is the same type of fluid or the first and second fluids are different types of fluid. The first fluid flowing through the driving nozzle may be referred to as a driving fluid. The first and second fluids may be provided from the same fluid source or from different and separate fluid sources.

In a particularly preferred embodiment of the present invention, the nozzle mechanism can be designed such that the first fluid is a gas and the second fluid is a gas and/or the second fluid is a liquid. In general, this nozzle design can be used with any suitable combination of liquid and/or gas. When gas is used as one or both of the fluids, air, fuel vapor, combustion gases, and mixtures thereof may be selected as one of the fluids.

The invention also relates to a jet pump comprising at least one nozzle mechanism according to claim 1 . The term jet pump may be understood to include additional components in addition to the nozzle mechanism. These additional components may include power sources, pressure sources, control devices, electronic connections, fluid connections, one or more fluid sources and/or fluid conduits.

Further details and advantages of the present invention are described with reference to the embodiments shown in the drawings.
1 shows a nozzle arrangement consisting of one driving nozzle and two suction nozzles.
2a, 2b are schematic diagrams of a nozzle mechanism according to the state of the art;
3A and 3B are schematic diagrams of a nozzle mechanism according to the present invention.

1 shows a nozzle mechanism for a jet pump. The term jet pump may be understood in a broad sense and may include additional components other than the actual nozzle shape shown in FIG. 1 . The nozzle mechanism includes a driving nozzle 10 and a first suction nozzle 1, the first suction nozzle 1 is disposed radially outside the driving nozzle 10, and the nozzle mechanism drives the driving nozzle 10. The fluid flow flowing through is designed to drive the fluid flowing through the first suction nozzle 1 . A nozzle arrangement may be arranged around the centerline (C). In particular, the nozzle mechanism can be at least partially symmetric about centerline C.

The first suction nozzle 1 may be concentrically disposed around the driving nozzle 10 . The drive nozzle 10 may have a circular cross section and may include a cylindrical conduit. Alternatively or additionally, the drive nozzle 10 may include a non-cylindrical conduit. The first suction nozzle 1 can have an axisymmetric volume or an axisymmetric conduit. At least a portion of the conduit of the driving nozzle 10 may be located within the conduit of the first suction nozzle 1 . In this case, the nozzle mechanism may exhibit rotational symmetry at least around the center line C at some locations along the center line C.

Alternatively, the nozzle mechanism may exhibit reflection symmetry with respect to a plane that includes centerline C and is perpendicular to the projection plane of FIG. 1 . In this case, the suction nozzle 1 and the drive nozzle 10 may comprise, for example, a cuboid or adjacent conduit. Further, the nozzle mechanism may not exhibit reflection symmetry with respect to the defined plane, but may still comprise wholly or at least partially a cuboid-shaped conduit. The term conduit can be understood to refer to a conduit currently bounded by a radially solid wall. The solid wall may completely enclose the conduit portion in a circumferential direction of the conduit portion.

The conduit of the driving nozzle 10 and the first suction nozzle 1 can be at least partially separated by a first wall 11 . The first wall 11 may comprise a conical portion and at least one cylindrical portion directly connected to the conical portion.

The right end or the downstream end of the first wall 11 can be referred to as an outlet of the driving nozzle 10, where the first fluid of the driving nozzle 10 and the second fluid of the first suction nozzle 1 are two fluids. interacts, so that the second fluid is driven by the first fluid. The inside of the first wall 11 can completely surround the drive nozzle 10 and define the cross-sectional area and shape of the drive nozzle 10 itself. An outer side of the first wall 11 may define an inner boundary of the first suction nozzle 1 . The inner and outer sides of the first wall 11 may include surfaces that are parallel or nearly parallel to each other. In particular, the first wall 11 may comprise at least one cylindrical portion or a portion having a constant cross-sectional area along the flow direction. This applies in particular to the furthest downstream part of the first wall 11 or to the part of the first wall 11 close to the farthest downstream part. The close alignment of these two faces of the first wall is such that the streamlines of the flow through the drive nozzle 10 and the streamlines of the flow through the first suction nozzle 1 either flow together or are parallel to each other when they meet. ensure that they are nearly parallel.

Downstream of the outlet of the drive nozzle 10, a first mixing tube 3 is provided. The direction of fluid flow is indicated by three arrows to the left and up of the nozzle mechanism. Around the centerline (C), the general direction of flow in Fig. 1 is from left to right. The downstream location of the component can therefore be found to the right of the nozzle mechanism component in FIG. 1 .

Thus, the first mixing tube 3 is provided downstream of the driving nozzle 10 and the first suction nozzle 1 . The diameter or cross-sectional area of the mixing tube 3 may be selected to accommodate the combined volume flow of the drive nozzle 10 and the primary suction nozzle 1 .

The first mixing tube 3 can be constrained by the second wall 32 and/or the first mixing tube 3 can partially or entirely comprise a cylindrical conduit. The length of the first mixing tube 3 can be chosen to be 2 to 5 times the width or diameter of the mixing tube 3 . In particular, the length of the mixing tube 3 can be chosen to be 2.5 to 4 times the width or diameter of the mixing tube 3 .

The first mixing tube 3 can be designed to include a first diffuser stage 31 at the downstream end of the first mixing tube 3 . The first diffuser stage 31 may in particular have a larger cross-sectional area, diameter or width than other parts of the first mixing tube 3, in particular upstream parts. The first diffuser stage 31 may be at or close to the most downstream part of the first mixing tube 3 . The first mixing tube 3 and the first diffuser stage 31 may be integrally formed by the second wall 32 .

The first diffuser stage 31 may be close to or part of a second suction nozzle 2 arranged downstream of the first mixing tube 3, the nozzle mechanism being such that the fluid flow through the first mixing tube 3 is is designed to drive the fluid through the second suction nozzle (2) and/or the second suction nozzle (2) is arranged concentrically around the first mixing tube (3) and/or the second suction nozzle (2) includes an axisymmetric volume surrounded by an inner wall and an outer wall.

As shown in the embodiment of FIG. 1 , the nozzle mechanism of the present invention may be one or more stage nozzle mechanisms including a plurality of suction nozzles 1 , 2 and/or driving nozzles 10 . Thus, the most downstream part of the first mixing tube 3, especially the outlet part of the first mixing tube 3, is part of another driving nozzle or another driving nozzle for driving the fluid through the second suction nozzle 2. can be considered

The first suction nozzle 1 in that the geometry of the second suction nozzle 2 can exhibit rotational symmetry around the centerline C or reflection symmetry similar to that of the first suction nozzle 1 described above. can correspond to the geometric structure of Alternatively, as described above, an asymmetrical embodiment is also possible. In addition, the wall forming the boundary of the second suction nozzle 2, that is, the second wall 32 inside the second suction nozzle 2 and another wall outside the second suction nozzle 2 are It can be oriented to closely align the flow through the 2 suction nozzles (2) with the flow through the first mixing tube (3). In particular, the second suction nozzle 2 may be provided so that the velocity vector of the fluid passing through the second suction nozzle 2 approaches the velocity vector of the fluid flow passing through the first mixing tube 3 in direction and magnitude. there is. The boundary wall of the second suction nozzle 2 is therefore oriented in the direction of the flow through the mixing tube 3 so that the flow through the first mixing tube 3 and the flow through the second suction nozzle 2 are mixed together with minimal losses. It can be parallel and/or angular.

A second mixing tube 4 may be provided downstream of the first mixing tube 3 and the second suction nozzle 2 . The second mixing tube 4 may include a cylindrical conduit and/or a second diffuser stage 41 at the downstream end of the second mixing tube 4 . The downstream end of the second mixing tube 4 is or can be connected to a fluid conduit.

During operation of the nozzle mechanism, a first fluid flows through the driving nozzle 10, a second fluid flows through the first suction nozzle 1 and/or the second suction nozzle 2, and the first fluid and the second fluid are of the same type. or the first and second fluids are different types of fluids. The first fluid of the driving nozzle 10 drives the fluid flowing through the suction nozzles 1 and 2, and the fluid may be a gas and/or a liquid.

The first suction nozzle 1 or the two or more suction nozzles 1 , 2 may be annular or near-annular nozzles that surround the circular drive nozzle 10 or at least partially surround a further drive nozzle. The actuating nozzle 10 may be concentrically enclosed or may be otherwise enclosed. The driving nozzle 10 may be a driving air nozzle. The nozzle mechanism may be used with a turbocharger of an internal combustion engine. In this case, the nozzle mechanism can be considered as part of a jet pump for pumping gas from a fuel tank to a combustion engine, for example.

Nozzles of the present invention can be designed so that adjacent nozzles have flow rates and/or flow directions that are as similar as possible. In particular, the nozzle is designed such that the flow direction and/or velocity of the first fluid flow exiting the drive nozzle 10 is as similar as possible to the second fluid flow exiting the first and/or second suction nozzles 1, 2. can be designed

The inventive nozzle arrangement and corresponding jet pump in fact provides at least one additional suction nozzle 1, 2 to increase the flow rate of the suction flow before it is mixed with the drive flow. The additional suction nozzles 1, 2 effectively reduce the generation of turbulence during mixing of at least two fluid flows, ie first and second fluid flows. As a result, the power and efficiency of the pump increases.

Power is supplied to the corresponding jet pump in the form of a motive mass flow, which is accelerated at the motive nozzle and thereby creates a high velocity and low pressure fluid jet. The resulting low pressure is used to draw the drive flow, ie the suction mass flow, which mixes with the first fluid flow, into the pump or nozzle mechanism. The drive mass flow rate or first fluid flow and the suction mass flow rate or second fluid flow leave the pump or nozzle arrangement after passing through one or more diffuser stages (31, 41) which increase the pressure of the flow.

One of the main advantages of jet pumps is their simple design, which requires no moving parts. The main disadvantages include the low efficiency of these pumps due to the mixing of the nearly stagnant fluid with the high-velocity jet.

2A shows a schematic diagram of a typical jet pump flow configuration known in the art. Figure 2b shows a simplified representation of the fluid flow in question. As shown in FIG. 2A, a high-velocity jet is created by the drive nozzle 10, which usually draws a suction mass flow with a very low velocity.

Figure 2b is an ideal representation of a typical jet pump flow. Slow suction mass flow is indicated by a short horizontal arrow. It mixes with the high-velocity jet indicated by the long horizontal arrow. The high velocity gradient shown leads to high shear stress. The flow shown in FIG. 2B shows only flow components in the jet direction, that is, in the horizontal direction.

The shear stress (τ) at the boundary between the jet and the suction mass flow or between the first and second fluid flows respectively increases with the velocity gradient of the corresponding fluid flow. The latter is usually very large because the difference in velocity between the two fluid flows is large. High shear stress causes turbulence, which in turn leads to low primary energy dissipation and low efficiency of the jet pump. A more efficient jet pump requires a reduction in the shear stress caused by the mixing of the two mass flows. Since the jet velocity is determined by the required pumping pressure, the only way to reduce the shear stress at the interface is to increase the flow rate of the suction flow in the direction of the jet flow.

3A and 3B show a jet pump flow configuration in which the suction flow is accelerated before mixing with the jet and the velocity gradient is reduced. This reduces the shear stress and therefore reduces the amount of turbulence created and dissipated energy. As a result, less energy is lost and the jet pump is more efficient. In Fig. 3a, the jet pump or nozzle mechanism comprises a driving nozzle 10 and a first suction nozzle 1 for suction flow. Figure 3b shows the ideal state of the flow. The suction flow rate is indicated by the short horizontal arrow and the jet flow rate by the long horizontal arrow. As shown, the difference between length and speed is smaller than the situation shown in FIG. 2B. Therefore, the shear stress is reduced. As before, the flow plotted in Fig. 3b shows only the flow component in the jet direction, i.e., the horizontal direction. Suction nozzles 1, 2 can be designed to direct the second fluid flow in a direction parallel to the first fluid flow or to approach the first fluid flow at a very small angle. To achieve this effect, the suction nozzles 1, 2 may have correspondingly angled borders.

The invention is particularly used for ventilation of crankcases and fuel tanks of vehicles. Due to leaks and fuel evaporation, these components must be vented using corresponding jet pumps to comply with current emission regulations. Here, air supplied to the internal combustion engine may be used as a driving fluid or a first fluid. The air provided can be compressed air, for example from a turbocharger or compressor. The present invention provides a high performance means for venting these components in full throttling operation and idle engine resulting in low drive pressure and high drive pressure. At the same time, the present invention provides a jet pump with low consumption of drive air or drive fluid at full throttling of the engine.

The present invention is not limited to the foregoing embodiments or features. The present invention may include various additions or modifications to the described embodiments.

All features and advantages arising from the claims, description and drawings, including structural details, spatial arrangements and procedural steps, may be essential to the invention individually and in the most varied combinations.

1: first suction nozzle
2: second suction nozzle
3: first mixing tube
4: second mixing tube
10: drive nozzle
11: first wall
31: first diffuser stage
32 second wall
41: second diffuser stage
C: center line

Claims (10)

A nozzle mechanism for a jet pump, wherein the nozzle mechanism includes a driving nozzle (10) and a first suction nozzle (1), and the first suction nozzle (1) is disposed radially outside the driving nozzle (10). The nozzle mechanism is characterized in that the fluid flow flowing through the actuating nozzle (10) drives the fluid passing through the first suction nozzle (1). According to claim 1,
A nozzle mechanism, characterized in that the first suction nozzle (1) is arranged concentrically around the drive nozzle (10) and/or the first suction nozzle (1) comprises an axisymmetric volume. According to claim 1 or 2,
A nozzle mechanism characterized in that a first mixing tube (3) is provided downstream of the driving nozzle (10) and the first suction nozzle (1). According to claim 3,
The nozzle mechanism, characterized in that the first mixing tube (3) comprises a first diffuser stage (31) at the downstream end of the first mixing tube (3). According to claim 3 or 4,
The second suction nozzle (2) is disposed downstream of the first mixing tube (3), and the nozzle mechanism is such that the fluid flow flowing through the first mixing tube (3) controls the fluid passing through the second suction nozzle (2). characterized in that the second suction nozzle (2) is arranged concentrically around the first mixing tube (3) and/or the second suction nozzle (2) comprises an axisymmetric volume. . According to claim 5,
A nozzle mechanism characterized in that a second mixing tube (4) is provided downstream of the first mixing tube (3) and the second suction nozzle (2). According to claim 6,
The nozzle mechanism, characterized in that the second mixing tube (4) comprises a second diffuser stage (41) at the downstream end of the second mixing tube (4). According to any one of claims 1 to 4,
The first fluid flows through the driving nozzle, the second fluid flows through the first suction nozzle 1 and/or the second suction nozzle 2, and the first fluid and the second fluid are the same kind of fluid and or the first fluid and the second fluid are different types of fluids. According to claim 8,
The nozzle mechanism, characterized in that the first fluid is a gas, the second fluid is a gas and/or the second fluid is a liquid. A jet pump comprising at least one nozzle mechanism according to claim 1 .

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