Injector having an actuation mechanism having a pilot valve and a balancing channel

Abstract

The invention relates to an injector (1; 100), for example for a refrigerant circuit, having a main inlet (2), an auxiliary inlet (7), an outlet (12), a nozzle (5) and a mixing section (6, 10). The injector (1; 100) comprises an actuation mechanism (30) that moves the needle (20) between an open position and a closed position. The actuation mechanism (30) comprises a piston (31) in a cylinder (35) wherein a first cylinder chamber (37) is in fluid communication with the main inlet (2) and a second cylinder chamber (38) is in fluid communication with the first cylinder chamber (37). The second cylinder chamber (38) is in fluid communication with the auxiliary inlet (7) and / or the outlet (12) via the discharge passage (39, 53, 54, 55, 56, 57) when a pilot valve (50) arranged in the discharge passage (39, 53, 54, 55, 56, 57) is in an open state. In order to ensure smooth opening and closing, fluid communication between the second cylinder chamber (38) and the first cylinder chamber (37) is provided by an equalization channel (32), the flow cross-section of which is larger than the flow cross-section of the discharge channel (39, 53, 54, 55, 56, 57).

Description

Technical Field

[0001] The invention relates to an ejector, for example for a refrigeration circuit with a circulating refrigerant, the ejector having a main (fluid) inlet, an auxiliary (fluid) inlet, a (fluid) outlet, a nozzle, and a mixing section for mixing a fluid supplied at high pressure at the main inlet and a fluid sucked in from the auxiliary inlet. The invention further relates to an ejector assembly having at least two ejectors. Background Art

[0002] Typically, the refrigeration circuit supplies fluid to the main inlet at a high pressure. Further, the refrigeration circuit supplies fluid to the auxiliary inlet at an auxiliary pressure less than the high pressure. The nozzle ejects the fluid received at the main inlet into the mixing section. Thus, the flow velocity increases. The fluid received at the auxiliary inlet is additionally sucked into the mixing section. Therefore, the fluid received at the main inlet is mixed with the fluid received at the auxiliary inlet in the mixing section. Thereafter, the combined fluid flow leaves the ejector through the outlet. The diffuser is arranged between the mixing section and the outlet. In some applications, the fluid can be prevented from flowing through the nozzle. Thus, the ejector is closed.

[0003] Examples of injectors are known from WO 2018 / 159320 A1, US 7,841,193 B2, JP 4 134 918 B2 and EP 1923 575 A2.

[0004] US 2004 / 0040340 A1 discloses an ejector, which includes a high-pressure refrigerant inlet port, a low-pressure refrigerant inlet port, a nozzle, a mixing part and a diffuser. The pilot valve controls the throttling opening of the nozzle according to the difference between the pressure of the refrigerant in the first pressurized compartment and the pressure of the medium-pressure refrigerant in the second pressurized compartment. The pressure of the refrigerant in the first pressurized compartment is the same as the pressure of the refrigerant in the high-pressure refrigerant inlet part. An orifice is provided in the pilot valve. The channel opening on one side of the high-pressure inlet port and the second pressurized compartment are connected to each other through the orifice. The control valve is connected to the second pressurized compartment fluid and controls the opening area of ​​the low-pressure refrigerant channel extending between the control valve and the low-pressure refrigerant inlet port.

[0005] The rapid opening or closing of the ejector can cause rapid pressure changes, such as pressure peaks, in the refrigeration circuit using the ejector. This can lead to damage to components of the refrigeration circuit. In addition, this can lead to instability in the control of the refrigeration system.

[0006] One approach is to use a stepper motor to control the opening and closing of the injector. However, stepper motors are extremely expensive and are not entirely suitable for all applications. Summary of the invention

[0007] It is therefore an object of the present invention to ensure smooth opening and closing of the injector in a cost-effective and reliable manner.

[0008] The above-mentioned problem is solved by an ejector which is used, for example, in a refrigeration circuit with a circulating refrigerant.

[0009] The injector includes:

[0010] a primary (fluid) inlet; an auxiliary (fluid) inlet; and a (fluid) outlet;

[0011] a nozzle for ejecting the fluid supplied at the primary inlet into the mixing section and for sucking the fluid supplied at the secondary inlet into the mixing section;

[0012] a needle and a needle holder, wherein the needle holder is arranged downstream of the primary inlet and upstream of the nozzle (and the outlet); and

[0013] an actuation mechanism for moving the needle between an open position in which the needle is lifted from the needle seat to allow fluid to flow through the needle seat and a closed position in which the needle abuts the needle seat and prevents fluid from flowing through the needle seat, wherein the actuation mechanism comprises:

[0014] a cylinder having a piston connected to the needle, wherein a first cylinder chamber is maximized when the needle is in its open position and a second cylinder chamber is maximized when the needle is in its closed position, wherein the first cylinder chamber is in fluid communication with the main inlet via a chamber inlet, and wherein the second cylinder chamber is in fluid communication with the first cylinder chamber, and

[0015] The exhaust passage has a pilot valve, wherein when the pilot valve is in an open state, the second cylinder chamber is in fluid communication with the auxiliary inlet and / or the outlet via the exhaust passage.

[0016] Fluid communication of the second cylinder chamber with the first cylinder chamber is provided by an equalizing passage.

[0017] The flow cross section of the equalizing channel may be larger than the flow cross section of the discharge channel.

[0018] The invention ensures smooth opening and closing of the injector. Pressure peaks due to rapid opening and / or closing are reliably avoided. The embodiment is cost-effective. For example, no expensive stepper motor is required to ensure smooth opening and closing.

[0019] Furthermore, when the needle is connected to the piston, the risk of the needle moving with excessive speed and / or wobbling due to external pressure fluctuations (eg due to fluctuations in the main pressure applied to the main inlet by an external refrigeration circuit) is reduced.

[0020] Fluid from the primary inlet may enter the first cylinder chamber via the chamber inlet. This allows the first cylinder chamber to be filled as (the volume of) the first cylinder chamber increases.

[0021] The exhaust passage is configured for exhausting fluid from the second cylinder chamber when the pilot valve is open. This allows (by displacement of the piston in the cylinder) the second cylinder chamber to be reduced (in volume).

[0022] The equalizing channel allows fluid to flow from the first cylinder chamber to the second cylinder chamber. To bring the needle from the open position to the closed position, the pilot valve is closed. When the pilot valve is closed, no fluid is discharged from the second cylinder chamber. The piston is displaced so as to maximize the (volume of) the second cylinder chamber. In more detail, when (the volume of) the second cylinder chamber increases, the second cylinder chamber is filled with fluid from the first cylinder chamber through the equalizing channel into the second cylinder chamber. At the same time, the (volume of) the first cylinder chamber decreases.

[0023] As mentioned above, if the needle is in the open position, this allows fluid to flow through the needle seat. In more detail, this allows fluid to flow from the primary inlet into the nozzle and further into the mixing section. When the needle is in its closed position, fluid is prevented from flowing from the primary inlet into the nozzle. Correspondingly, no fluid is sucked into the mixing section from the auxiliary inlet. Therefore, the injector is then in a closed state.

[0024] According to one aspect, when the solenoid valve is in a closed state, the exhaust passage is blocked (closed).

[0025] The chamber inlet, the equalizing channel and the discharge channel may be completely integrated in the ejector. They are not constituted by a fluid connection provided by the environment or any external element. In particular, they are not constituted by any fluid connection of a refrigeration circuit employing the ejector that is not part of the ejector itself.

[0026] According to one aspect, the actuation mechanism is used to move the needle along the longitudinal direction between an open position and a closed position. The cylinder can extend parallel to the longitudinal axis, and the piston can be configured to reciprocate in the cylinder parallel to the longitudinal axis to maximize (the volume of) the first cylinder chamber (so that the needle is in the open position) or maximize (the volume of) the second cylinder chamber (so that the needle is in the closed position).

[0027] The longitudinal direction may be parallel to the central axis. The cylinder, piston, needle, needle seat, nozzle and / or mixing section may extend at least substantially along the central axis. The diffuser section may be formed downstream of the mixing section. The diffuser section may extend along the central axis. In one embodiment, the (entire) injector extends substantially along the central axis.

[0028] The piston area is the cross-sectional area of ​​the piston. The piston area may be defined in a plane perpendicular to the longitudinal direction.

[0029] In one embodiment, the piston area is at least 1000 times the flow cross section of the equalizing channel. In particular, the piston area may be at least 1600 times the flow cross section of the equalizing channel.

[0030] If the piston area is increased, a displacement of the piston by a certain distance corresponds to a larger volume change of the second cylinder chamber. This helps to limit the speed of the piston.

[0031] During the transition of the needle from the open position to the closed position, the fluid flows from the first cylinder chamber through the equalizing channel to the second cylinder chamber. For a given situation, the flow cross section of the equalizing channel limits the flow rate between the first cylinder chamber and the second cylinder chamber (e.g. measured in ml / s) by its flow resistance. The total volume change of the second cylinder chamber during the opening period increases with the increase of the piston diameter. By increasing the piston area while the flow cross section of the equalizing channel and the stroke of the piston remain unchanged, the closing time is extended. The speed of the piston is slow during the closing period. In more detail, the speed of the piston reaches a substantially constant value shortly after the transition from the open position to the closed position has begun. This value can be related to the flow rate divided by the piston area.

[0032] Additionally or alternatively, the piston area may be at least 1200 times, in particular at least 1920 times, the flow cross section of the discharge channel.

[0033] For a given situation, the flow cross-section of the discharge channel limits the fluid discharge rate (e.g. measured in ml / s) at which the fluid can be discharged from the second cylinder chamber via the discharge channel when the pilot valve is opened. During the transition from the closed position to the open position, the net flow rate of the second cylinder chamber can be determined (at least substantially) by the fluid discharge rate and the flow rate of the fluid entering through the equalization channel. Shortly after the transition from the closed position to the second position has begun, the speed of the piston can reach a substantially constant value. This value can be related to the net flow rate divided by the piston area. If the piston area is increased and thus the total volume change of the second cylinder chamber required for opening is increased, the opening time is extended.

[0034] Naturally, if the piston area increases relative to the flow cross section of the equalizing channel while the flow cross section of the discharge channel remains unchanged, the piston area also increases relative to the discharge channel. Vice versa, if the piston area increases relative to the flow cross section of the discharge channel while the flow cross section of the discharge channel remains unchanged, the piston area also increases relative to the equalizing channel.

[0035] According to one aspect, the needle seat area, i.e. the cross-sectional area of ​​the needle seat when the needle engages the needle seat in the closed position, is in the range of 1.005 to 1.4 times the flow cross-sectional area of ​​the nozzle. The cross-sectional area of ​​the needle seat is particularly small. Therefore, when the needle reaches the needle seat and begins to lift from the needle seat, the effect of pressure changes at the needle tip is minimized. This facilitates smooth and controlled opening and closing of the injector.

[0036] According to a further aspect, the injector may comprise a housing. This ensures protection of the components inside the housing.

[0037] The housing may include a main sleeve. The interior of the main sleeve may extend along the central axis. The housing may further include a top cover. The top cover may be fixed to the end of the main sleeve on the side opposite to the outlet in the longitudinal direction. The top cover may be removably fixed to the main sleeve. This facilitates maintenance.

[0038] According to another aspect, the pilot valve is a solenoid valve. Solenoid valves are particularly cheap, reliable, and easy to control. It is not necessary to control the exact degree of opening of the pilot valve. The invention also ensures smooth opening and closing in the case where the pilot valve can only be switched between an open state and a closed state. No additional intermediate states of the pilot valve are required to keep the movement speed of the needle below a predetermined threshold.

[0039] In one embodiment, the piston area corresponds to at least 20 times the needle seat area. Thus, when the needle reaches the needle seat and begins to lift from the needle seat, the effect of pressure changes can be at least substantially negligible compared to the effect of fluid flowing into and out of the first cylinder chamber and the second cylinder chamber.

[0040] According to one aspect, the travel of the needle between the closed position and the open position corresponds to at least 2*(A noz / π) 0.5 , where A noz is the flow cross section of the nozzle. When the needle is in its open position, the needle is sufficiently retracted to ensure low flow resistance to the fluid flowing from the primary inlet to the nozzle. This is beneficial for efficiency.

[0041] According to another aspect, the ejector comprises a non-return valve function for preventing the flow of fluid from the outlet to the auxiliary inlet. Thus, the components of the refrigeration circuit in which the ejector is employed are not damaged by such a backflow.

[0042] The first cylinder chamber may be a piston rod side cylinder chamber. The second cylinder chamber may be a cylinder chamber on the other side of the piston in the same cylinder.

[0043] According to one aspect, the needle may be formed integrally with the piston. The needle may at the same time be the piston rod. This is a particularly reliable, cost-effective and lightweight embodiment. It may comprise at least one hole extending through the piston.

[0044] In one embodiment, the equalizing channel is (entirely) formed in the piston. This allows for fast and cost-effective production.

[0045] According to another aspect, the flow cross section of the equalizing channel can be in the range of 1.2 to 2.5 times the flow cross section of the discharge channel when the pilot valve is in its open state. This ensures that the flow resistance of the discharge channel is higher than the flow resistance of the equalizing channel. Even during the transition of the needle from the closed position to the open position, only a slight pressure drop from the first cylinder chamber to the second cylinder part occurs. The movement speed of the piston and the needle can be accurately controlled and kept low. This further facilitates the smooth opening of the injector.

[0046] The flow cross section of the discharge channel can be determined by the flow cross section of the pilot valve. The pilot valve can be designed to be as small as possible. This reduces costs. Therefore, the flow cross section of the equalization channel can be in the range of 1.2 to 2.5 times the flow cross section of the pilot valve when the pilot valve is in its open state.

[0047] In one embodiment, the flow cross section of the chamber inlet is larger than the flow cross section of the equalizing channel. For example, the flow cross section of the chamber inlet may be at least 5 times, in particular at least 10 times, larger than the flow cross section of the equalizing channel. The amount of fluid leaving the first cylinder chamber through the equalizing channel may be easily changed, in particular in the case of an open pilot valve. This ensures that the pressure in the first cylinder chamber is at least substantially maintained when the pilot valve is open and even during the transition from the closed state to the open state, i.e. when the (volume) of the first cylinder chamber increases.

[0048] According to one aspect, the needle seat is at least axially fixed relative to the housing. This facilitates accurate opening and closing of the injector.

[0049] The nozzle may be arranged in the interior of the housing. The nozzle may be fixed at least axially relative to the housing. The nozzle may include a throat portion and a diverging nozzle portion. The throat portion may define a flow cross section of the nozzle. The diverging nozzle portion may be arranged downstream of the throat portion. It may have a conical shape, wherein the inner diameter increases towards the downstream end of the nozzle. The downstream end of the nozzle may protrude towards the mixing portion.

[0050] In one embodiment, the nozzle inlet is formed directly upstream of the nozzle, wherein the nozzle inlet tapers towards the nozzle, wherein the needle seat is located in the nozzle inlet, and wherein the length of the nozzle inlet may correspond to at least 1.8 times the travel of the needle between the closed position and the open position. This ensures proper flow from the fluid supplied at the main inlet into the nozzle when the injector is in the open state, and thus ensures low flow resistance.

[0051] The nozzle inlet and the nozzle may be formed as a one-piece component, for example as a nozzle insert. The nozzle insert may be mounted to an insert assembly holder mounted in the housing, for example inside the main sleeve. The nozzle insert may be fixed to the housing. However, the nozzle insert may be removably fixed to the housing to facilitate maintenance.

[0052] According to one aspect, the injector may include a resilient member that prevents the piston from minimizing (the volume of) the second cylinder chamber. For example, the resilient member pushes the piston towards maximizing (the volume of) the second cylinder chamber. In other words, the resilient member may push the needle towards its closed position. The resilient member may engage directly with the piston and / or engage directly with the needle. For example, the resilient member may be arranged between the end wall of the cylinder on the side of the second cylinder chamber and the piston. The resilient member facilitates the needle to transition from its open position to its closed position. The resilient member may include a helical spring.

[0053] In one embodiment, the ejector is configured such that the opening time of the needle is at least 0.5 s, such as at least 1 s. The long opening time prevents rapid pressure changes and thus reduces the risk of damage in a refrigeration circuit employing an ejector.

[0054] Additionally or alternatively, the ejector is configured such that the closing time of the needle is at least 1 s, such as at least 2 s. A long closing time prevents rapid pressure changes and thus reduces the risk of damage in a refrigeration circuit employing an ejector.

[0055] In one embodiment, the ejector is configured so that the needle moves at a substantially constant speed over a displacement length corresponding to at least 70% of the stroke during the transition from its closed position to its open position (in normal operation). This ensures a controlled and smooth opening and reduces the risk of damage in any refrigeration circuit employing the ejector.

[0056] Additionally or alternatively, the ejector is configured so that the needle moves at a substantially constant speed over a displacement length corresponding to at least 70% of the stroke during the transition from its open position to its closed position (in normal operation). This ensures a controlled and smooth closure and reduces the risk of damage in any refrigeration circuit employing the ejector.

[0057] A substantially constant speed may mean that the speed varies by a maximum of 15% during the respective movement phase.

[0058] According to another aspect, the flow cross section of the nozzle is at least 50 mm². Thus, the ejector exhibits a high capacity.

[0059] In one embodiment, the cylinder is formed by a cylinder insert and a top cover. The cylinder insert can be inserted into the interior of the main sleeve. The cylinder insert can be removably mounted in the main sleeve. This facilitates maintenance.

[0060] According to another aspect, the injector may comprise an elastic member, such as a spring, in particular a helical spring.

[0061] The resilient member may bias the cylinder insert against the top cover. The second cylinder chamber may be arranged on that side of the top cover. This ensures a proper seal between these elements. This ensures that the pressure propagation to the second cylinder chamber is determined by the pressure propagation from the first cylinder chamber to the second cylinder chamber via the equalizing channel. The risk of substantial leakage and pressure propagation from the main inlet to the second cylinder chamber bypassing the equalizing channel is reduced. The annular end face of the cylinder insert for abutment on the top cover may be ground flat.

[0062] The resilient member may be compressed between the cylinder insert and a member that is at least axially fixed relative to the housing. For example, the resilient member may be compressed between the cylinder insert and the insert assembly retainer.

[0063] In one embodiment, the injector comprises a filter between the main inlet and the needle seat. The filter may be arranged circumferentially around the needle and the needle seat. It may be supported by a resilient member.

[0064] According to another aspect, the needle is made of a first material and the needle seat is made of a second material, wherein the hardness of the second material is higher than the hardness of the first material. For example, the hardness of the second material may correspond to at least 1.4 times the hardness of the second material. In one embodiment, the nozzle insert (which includes the needle seat) is made of the second material.

[0065] In one embodiment, the needle tip portion of the needle includes an intermediate section with a reduced taper, such as a cylindrical intermediate section. The cylindrical intermediate section causes a "dead zone" when opening, especially in the initial stage of opening: when the needle has not moved at least a certain distance away from the abutment with the needle seat, no fluid flows out of the nozzle. In other words, a large amount of fluid flowing out of the nozzle requires the needle to move at least a certain distance away from the abutment with the needle seat. This reduces the sensitivity of the injector to pressure and / or flow pulsations of the fluid, especially at the main inlet. In the absence of a dead zone, even small pulsations of the fluid may lift the needle, and this may result in undesirable pulsating fluid flowing out of the nozzle.

[0066] The problem stated above is further solved by an injector assembly comprising at least two injectors according to any of the described embodiments and variants.

[0067] The injectors can be arranged in parallel.

[0068] In one embodiment, the flow cross section of the second of the at least two injectors is different from the flow cross section of the first of the at least two injectors. For example, the flow cross section of the second injector may be at least 1.2 times the flow cross section of the first injector. Four different flow rates may be set by closing both the first and second injectors, opening only the first injector, opening only the second injector, or opening both the first and second injectors.

[0069] If it refers to the flow cross section of an element like a channel, a channel or the like, for example a nozzle, this may mean the smallest cross section of the respective element along the intended flow direction through the element.

[0070] Additional features, advantages and possible applications of the invention are derived from the following description of exemplary embodiments and the accompanying drawings. All features described and / or illustrated diagrammatically herein form the subject matter of the invention either individually or in any desired combination, regardless of how they are combined in the claims or in their retroactive references to preceding claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 An embodiment of an injector according to the invention in an open state is shown in a cross-sectional view on a plane extending along the central axis of the injector;

[0072] Figure 2 yes Figure 1 An enlarged screenshot of the upper part;

[0073] Figure 3 The cross-sectional view is also along the central axis of the injector but perpendicular to the Figure 1 and Figure 2 The plane shown in the figure is shown on the plane Figure 2 an upper portion of an ejector;

[0074] Figure 4 Shows Figure 1 An enlarged cross section around the needle seat and nozzle,

[0075] Figure 5 A second embodiment of an injector according to the invention in an open state is shown in cross-sectional view in a plane extending along the central axis of the injector: and

[0076] Figure 6 yes Figure 5 An enlarged cross section around the needle tip. DETAILED DESCRIPTION

[0077] Figure 1An embodiment of an injector 1 according to the invention is shown in FIG. The injector 1 comprises a main (fluid) inlet 2, an auxiliary (fluid) inlet 7 and a (fluid) outlet 12. The main inlet 2 may also be referred to as a high pressure inlet 2. The injector 1 extends along a central axis C. The longitudinal direction L is parallel to the central axis C.

[0078] If injector 1 is in Figures 1 to 4 , the fluid can flow from the first inlet 2 through the nozzle 5, the mixing section (which includes the converging mixing section 6 and the cylindrical mixing section 10) and the diffuser section 11 to the fluid outlet 12. In addition, the fluid is drawn into the mixing section 6 from the auxiliary inlet 7. In other words, the fluid drawn from the auxiliary inlet 7 merges with the fluid from the main inlet 2 in the converging mixing section 6. This results in mixing of the fluid from the main inlet 2 and the fluid drawn from the auxiliary inlet 7 in the converging mixing section 6 and the cylindrical mixing section 10 connected downstream of the converging mixing section 6.

[0079] The injector 1 comprises a needle valve mechanism having a needle 20 and a needle seat 26 .

[0080] If the needle 20 is in the closed position (not shown), it abuts the needle seat 26 and blocks the fluid connection between the main inlet 1 and the nozzle 5. This prevents the fluid from the main inlet 1 from possibly entering the nozzle 5 and further flowing into the converging mixing section 6. This corresponds to the closed state of the injector 1.

[0081] If the needle 20 is in the Figures 1 to 4 , the needle 20 is lifted from the needle seat 26 by a needle stroke S (see Figure 4 ). This allows fluid to flow from the main inlet 2 into the nozzle 5. The stroke S is the displacement of the needle 20 along the longitudinal direction L between its open position and its closed position. The stroke S may be at least 10 mm, for example in the range of 12 mm to 30 mm.

[0082] In this exemplary embodiment, the housing 70 of the injector 1 includes a main sleeve 71, an upstream top cover 76, a first diffuser pipe 74, and a second diffuser pipe 75. The first diffuser pipe 74 and the second diffuser pipe 75 form at least a downstream portion of the diffuser portion 11. The housing 70 further includes a main (fluid) inlet connector 72, which is fixed to the main sleeve 71 and forms the main inlet 2, and an auxiliary (fluid) inlet connector 73, which is fixed to the main sleeve 71 and forms the auxiliary inlet 7.

[0083] The injector 1 further comprises an actuation mechanism 30 for moving the needle 20 along the longitudinal direction L between an open position and a closed position.

[0084] The actuating mechanism 30 comprises a pilot valve 50 and a piston 31. The piston 31 is arranged in a cylinder 35 and can be displaced axially (i.e., along a central axis C) within the cylinder 35. The needle 20 is mechanically connected to the piston 31 so that an axial movement of the piston 31 in the cylinder 35 is transferred as a movement of the needle 20 along a longitudinal direction L. Thus, the needle 20 can be moved from its open position to its closed position, and vice versa, by a corresponding axial movement of the piston 31. In this embodiment, the needle 20, the piston 31 and the cylinder 35 are all coaxially arranged along the central axis C, and the needle 20 is at least axially fixed to the piston 31. In more detail, the needle 20 and the piston 31 can be formed integrally (one-piece), such as Figures 1 to 3 In other words, the needle 20 (particularly the needle rod 25 ) also constitutes the piston rod of the piston 31 .

[0085] The cylinder 35 may be formed by a cylinder insert 77 and a top cover 76, as shown in FIG. Figures 1 to 3 The cylinder insert 77 is arranged inside the main sleeve 71 and directly abuts the top cover 76. The cylinder insert 77 guides the piston 31 and its piston rod (in this embodiment, the needle 20).

[0086] The piston 31 is configured to form a first cylinder chamber 37 and a second cylinder chamber 38 within the cylinder 35. The piston may divide the interior of the cylinder 35 (along the longitudinal direction L) into the first cylinder chamber 37 and the second cylinder chamber 38.

[0087] When the needle 20 is in its open position, the volume of the first cylinder chamber 37 is maximized (largest). When the needle 20 is in its closed position, this volume is minimized. When the needle 20 is in its closed position (not shown, corresponding to Figures 1 to 3 ), the volume can be reduced (at least substantially) to a minimum volume (small residual volume) when the piston 31 is in the lowest possible position.

[0088] If the needle 20 is in its closed position, the volume of the second cylinder chamber 38 is maximized (largest). When the needle 20 is in its open position (corresponding to the highest possible position of the piston 31, such as Figures 1 to 3 ), this volume is minimized. When the needle 20 is in its open position, this volume can be reduced (at least substantially) to zero. However, in this exemplary embodiment, the annular end wall 40 (arranged on the surface of the piston 31 facing the second cylinder chamber 38) is such that the residual volume of the second cylinder chamber 38 is maintained even when the needle 20 is in its open position. This ensures that the equalization channel 32 is not closed when the needle 20 is in its open position.

[0089] On that side of the cylinder insert 77 which faces away from the top cover 76 in the longitudinal direction L, a main (fluid) inlet chamber 3 is formed. A main inlet connector 72 opens into the main inlet chamber 3 .

[0090] The first cylinder chamber 37 is in fluid communication with the main inlet 2 via the chamber inlet 36. In this embodiment, the chamber inlet 36 is provided at the end of the main inlet chamber 3 and the cylinder 35 on the needle 20 side in the longitudinal direction L (the end of the cylinder 35 on the first cylinder chamber 37 side, i.e., Figures 1 to 3 The chamber inlet 36 may be formed in the cylinder insert 77, for example as at least one hole extending along the longitudinal direction L. Figure 1 and Figure 2 In the embodiment shown in , four or six such holes are formed in the cylinder insert 77. Figure 1 and Figure 2 Two of the holes can be seen in the figure.

[0091] Further, the other end of the cylinder 35 in the longitudinal direction L (the end of the cylinder 35 on the side of the second cylinder chamber 38, that is, Figures 1 to 3 The upper end of the cylinder 35 in the second cylinder chamber 38 is in fluid communication with the auxiliary inlet 7 via a discharge channel. The pilot valve 50 is arranged in the discharge channel. When the pilot valve 50 is in its closed state, it blocks (closes) the discharge channel. When the pilot valve 50 is in its open state, the discharge channel is open and the second cylinder chamber 38 is in fluid communication with the auxiliary inlet 7. In other words, the discharge channel is formed between the second cylinder chamber 38 on the one hand and the auxiliary inlet 7 on the other hand and / or a space that is in (direct) fluid communication with the auxiliary inlet 7. In this embodiment, the discharge channel is formed between the second cylinder chamber 38 and the auxiliary (fluid) inlet chamber 8, which is in direct fluid communication with the auxiliary inlet 7.

[0092] In a variant (not shown), when the pilot valve 50 is in the open state, the second cylinder chamber 38 is in fluid communication with the outlet 12 via the discharge channel. In other words, the discharge channel having the solenoid valve 50 is formed between the second cylinder chamber 38 and the fluid outlet 12 and / or the space in fluid communication with the fluid outlet 12 in this case. Of course, it is also possible to provide a discharge channel having two branches, one branch for fluid communication between the second cylinder chamber 38 and the auxiliary inlet 7 and the other branch for fluid communication between the second cylinder chamber 38 and the fluid outlet 12. A blocking device (e.g., a check valve) may be used to prevent the fluid from flowing from the auxiliary inlet 7 to the fluid outlet 12 via the discharge channel.

[0093] like Figure 1 As shown, the discharge channel can be formed completely in the injector 1. The discharge channel itself is integrated in the injector 1.

[0094] Now go to Figure 3, the exhaust passage includes a fluid connection 39 between the upper end of the cylinder 35 (the second cylinder chamber 38) and the upstream side of the pilot valve 50. The fluid connection 39 may also be referred to as a chamber outlet 39. As in Figure 3 As can be seen in FIG. 8 , the chamber outlet 39 may be formed by at least one channel (eg, two channels) in the top cover 76 .

[0095] Further, the downstream side of the pilot valve 50 is in fluid communication with the auxiliary inlet 7. Figure 1 and Figure 2 The plane of the cross section depicted is perpendicular to Figure 3 . In this embodiment, the exhaust passage includes a first fluid passage 54 formed in the top cover 76, a second fluid passage 55 also formed in the top cover 76, a fluid passage 56 formed in the main sleeve 71, and a fluid passage 57 formed between the main sleeve 71 and the insert assembly retainer 78. The fluid passage 57 is a substantially annular gap between the main sleeve 71 and the insert assembly retainer 78. The exhaust passage leads to the auxiliary inlet chamber 8. The auxiliary inlet connector 73 also leads to the auxiliary inlet chamber 8. Therefore, when the pilot valve 50 is in its open state, the downstream side of the pilot valve 50 is in fluid communication with the auxiliary inlet 7, and the second cylinder chamber 38 is in fluid communication with the auxiliary inlet 7.

[0096] In addition, the second cylinder chamber 38 is in fluid communication with the first cylinder chamber 37. The fluid communication is provided by an equalizing channel 32. In this embodiment, the equalizing channel 32 comprises a longitudinal hole through the piston 31. The equalizing channel 32 may be formed completely within the injector 1. The equalizing channel itself is integrated in the injector 1.

[0097] The pilot valve 50 includes a valve seat 51, a valve member 52 and an actuator 53. The actuator 53 is configured to switch the pilot valve 50 between its open state and its closed state. In this embodiment, the pilot valve 50 is a solenoid valve. Therefore, the actuator 53 is an electromagnetic actuator. The pilot valve 50 is a part of the injector 1. In particular, the valve seat 51 can be formed integrally with the housing 70 or an insert fixed to the housing. In the exemplary embodiment, the valve seat 51 is installed in the top cover 76.

[0098] Hereinafter, the operation will be described. It is assumed that at the start the needle 20 is in its open position, and the pilot valve 50 is in its open state. In other words, at the start the injector 1 is in its open state.

[0099] In normal operation, fluid is supplied at a high main pressure at the main inlet 2. Therefore, the high pressure fluid from the main inlet 2 flows through the chamber inlet 36 into the first cylinder chamber 37. The (minimum) flow cross section A of the chamber inlet 36 is pci Greater than the (minimum) flow cross section A of the equalizing channel 32eq For example, the flow cross section A of the chamber inlet 36 is pci The flow cross section A of the equalization channel 32 may be eq At least 5 times, in particular at least 10 times. Figure 1 In the exemplary embodiment shown in FIG. , the flow cross section A of the chamber inlet 36 is pci is the sum of the cross-sectional areas of the holes constituting the chamber inlet 36 , which are formed in the cylinder insert 77 .

[0100] Due to the chamber inlet 36, the fluid pressure in the first cylinder chamber 37 corresponds at least substantially to the pressure prevailing at the main inlet 2. The fluid pressure in the first cylinder chamber 37 forces the piston 31 (along the longitudinal direction L) towards the cap 76 and, therefore, the needle 20 towards its open position, counteracting the elastic force provided by the elastic member 33. In the depicted embodiment, the elastic member 33 is a helical spring.

[0101] In normal operation, fluid is supplied at an auxiliary pressure at the auxiliary inlet 7. The auxiliary pressure is less than the main pressure at the main inlet 2, but higher than the outlet pressure at the fluid outlet 12. In other words, there is a pressure drop from the main pressure to the auxiliary pressure. When the needle 20 is in its open position, this pressure drop is used to eject the fluid from the main inlet chamber 3 through the nozzle 5 into the converging mixing section 6. The fluid ejected from the nozzle 5 has a high speed. The ejection through the nozzle 5 causes a pressure drop from the main inlet chamber 3 to the converging mixing section 6. Further, when the needle 20 is in its open position so that the fluid provided at the main inlet 2 is ejected from the nozzle 5, the fluid provided at the auxiliary inlet 7 is sucked from the auxiliary inlet chamber 8 through the auxiliary fluid passage 9 into the converging mixing section 6. The fluid from the main inlet 2, ejected by the nozzle 5 and the fluid sucked from the auxiliary inlet chamber 8 are mixed in the converging mixing section 6 and the cylindrical mixing section 10.

[0102] As described above, it is assumed that at the beginning the pilot valve 50 is in its open state. A small fluid flow from the first cylinder chamber 37 to the second cylinder chamber 38 occurs via the equalizing passage 32. In addition, since the pilot valve 50 is in its open state, fluid flows from the second cylinder chamber 38 to the auxiliary inlet chamber 8 via the exhaust passage. Therefore, there is a small pressure drop from the first cylinder chamber 37 to the second cylinder chamber 38, which is sufficient to keep the needle 20 in the open position. The pressure drop is high enough to keep the piston 31 against the top cover 76 against the restoring force of the elastic element 33.

[0103] Flow cross section A of the equalization channel 32 eq is relatively small. It may be less than 10 mm², for example in the range of 0.5 mm² to 4 mm². Additionally or alternatively, it corresponds to the length L of the equalizing channel 32 (along the flow direction therethrough) eqThe square value of can be the flow cross section A of the equalizing channel 32 eq at least 15 times, for example at least 25 times (L eq ²≥15*A eq ). The equalizing channel 32 presents a considerable flow resistance.

[0104] If the equalizing channel 32 has a cylindrical shape, its flow cross section A eq is π*(D eq / 2)², where D eq is the diameter of the equalizing passage 32 .

[0105] Typically, the flow cross section A of the equalization channel 32 is eq may be greater than or equal to (when the pilot valve 50 is in its open state) the (minimum) flow cross section A of the discharge channel dp .

[0106] When the injector 1 is in the open state, an intermediate pressure is generated in the second cylinder chamber 38. The intermediate pressure is lower than the pressure in the first cylinder chamber 37 (which can correspond at least substantially to the main pressure). The intermediate pressure is greater than the auxiliary pressure. The exact value of the intermediate pressure depends in particular on the flow resistance of the equalizing channel 32 and thus on the flow cross section A of the equalizing channel. eq , also depends on the flow resistance of the discharge channel and thus on the flow cross section A of the discharge channel. dp , and depends on the ratio A eq / A dp .

[0107] If the flow cross section A of the equalizing channel 32 eq Significantly smaller than the flow cross section A of the discharge channel dp (A eq / A dp <<1), the flow resistance of the discharge passage is significantly smaller than the flow resistance of the equalizing passage 32. When the pilot valve 50 is open, the fluid can be discharged from the second cylinder chamber 38 into the auxiliary inlet chamber 8 through the discharge passage in an almost unimpeded manner. If the pilot valve 50 is in its open state, the intermediate pressure in the second cylinder chamber 38 will become almost as low as the auxiliary pressure.

[0108] However, according to one aspect of the present disclosure, the flow cross section A of the equalization channel 32 is eq Can be larger than the flow cross section A of the discharge channel dp (A eq / A dp >1). In particular, the flow cross section A of the equalization channel 32 eq The flow cross section A in the discharge channel can be dpIn the range of 1.2 to 2.5 times (1.2*A dp ≤A eq ≤2.5*A dp ). The flow resistance of the equalizing channel 32 is less than the flow resistance of the discharge channel. However, in this case, the pressure drop from the first cylinder chamber 37 to the second cylinder chamber 38 is small. However, when the pilot valve 50 is in its open state, the intermediate pressure in the second cylinder chamber 38 is less than the pressure in the first cylinder chamber 37. In other words, despite this, there is still a small pressure drop. The small pressure drop is maintained due to the flow resistance exhibited by the equalizing channel 32 and due to the continuous discharge of the fluid flowing out of the second cylinder chamber 38. For example, the injector 1 can be configured so that in normal operation, if the pilot valve 50 is opened for at least 0.2s, the pressure drop from the first cylinder chamber 37 to the second cylinder chamber 38 (i.e., the pressure drop along the equalizing channel 32) is less than 10 bar, in particular less than 3 bar. This ensures a smooth transition from the closed position of the needle 20 to its open position (and therefore a smooth transition from the closed state of the injector 1 to the open state of the injector 1) even if the actuation mechanism is controlled by a solenoid valve.

[0109] Thus, the injector 1 may be configured such that in normal operation the opening time of the needle 20 is at least 0.5 s, in particular at least 1 s. The opening time may be the time required for the needle 20 to move from its closed position to its open position in normal operation.

[0110] When the pilot valve 50 is in its open state, the (minimum) flow cross section A of the discharge channel dp It can correspond to the flow cross section A of the pilot valve 50 pv .

[0111] Starting from the situation in which the needle 20 is in its open position and the pilot valve 50 is open, as long as the pilot valve 50 remains open, the intermediate pressure is less than the pressure in the first cylinder chamber 37. The needle 20 remains in its open position while the pilot valve 50 remains open. The injector 1 is configured so that, in this situation, the force acting on the piston 31 generated by the pressure difference between the intermediate pressure in the second cylinder chamber 38 and the pressure in the first cylinder chamber 37 is sufficient to (at least substantially) overcome the elastic force of the spring 33.

[0112] It is now assumed that the pilot valve 50 is closed in this situation. No more fluid can be discharged from the second cylinder chamber 38 to the auxiliary inlet chamber 8. When the equalizing channel 32 remains open, the pressure in the second cylinder chamber 38 increases towards the pressure in the first cylinder chamber 37 (which may at least substantially correspond to the prevailing pressure). In addition, the resilient member 33 pushes the piston 31 away from the top cover 76. The piston 31 starts to move along the longitudinal direction L towards the needle seat 26. As a result, the needle 20 starts to move along the longitudinal direction L towards the needle seat 26 (i.e., towards its closed position).

[0113] Flow cross section A of the equalization channel 32 eq The piston area A of the piston 31 P Small. Piston area A P The flow cross section A of the equalization channel 32 may correspond to eq At least 1000 times, for example at least 1600 times, in particular at least 2100 times. This limits the movement speed of the piston 31.

[0114] This ensures a smooth transition from the open position of the needle 20 to its closed position (and therefore from the open state of the injector 1 to the closed state of the injector 1 ) even if the actuation mechanism is controlled by a solenoid valve which can only be switched between an open state and a closed state and does not offer the possibility of adjusting any degree of opening in between.

[0115] The injector 1 may be configured such that in normal operation the closing time of the needle 20 is at least 1 s, in particular at least 2 s. The closing time may be the time required for the needle 20 to move from its open position to its closed position in normal operation.

[0116] For example, the piston area A P Available in the range from 2000mm² to 10000mm².

[0117] If the piston 31 has a rotationally symmetrical basic shape, its flow cross section A p is π*(D p / 2)², where D p is the diameter of the piston 31 .

[0118] At the end of the transition from the open state of the ejector 1 to its closed state, the needle 20 abuts against the needle seat 26. The fluid connection from the primary inlet chamber 3 to the nozzle 5 (and therefore from the primary inlet 2 to the nozzle 5) is blocked. The nozzle 5 no longer ejects fluid. Therefore, no additional fluid is drawn from the secondary inlet 7 into the converging mixing portion 6.

[0119] In order to bring the injector 1 from its closed state to its open state again, the pilot valve 50 is opened again. Fluid is discharged from the second cylinder chamber 38 to the auxiliary inlet chamber 8, and the pressure in the second cylinder chamber 38 decreases towards the above-mentioned intermediate pressure. Due to the pressure drop from the first cylinder chamber 37 and the second cylinder chamber 38, the piston 31 starts to move in the longitudinal direction L, so that the needle 20 is retracted from the needle seat 26 towards the open position.

[0120] The cross-sectional area A of the needle seat 26 nsz (Needle seat area A ns ) is only slightly larger than the (smallest) flow cross section A of the nozzle 5 noz In particular, the needle seat area A nsz The flow cross section A of the nozzle 5 can be noz This allows the needle 20 to have a small diameter. Therefore, if the needle 20 is in its open position, the flow resistance of the fluid flowing from the main inlet 2 to the nozzle 5 is particularly low. In addition, the relatively small needle seat area A nsz A smooth and precise start of the transition from the closed position of the needle 20 to its open position is ensured.

[0121] Typically, an increased initial force is required to initiate the transition from the closed position to the open position (i.e., to retract the needle 20 from the closed position, in particular from abutment with the needle seat 26). The force required to further retract the needle 20 may decrease. The initial force depends, among other things, on the size of the contact area between the needle 20 and the needle seat 26. The initial force must be provided by the actuation mechanism 30. The needle seat area A nsz As close as possible to the flow cross section A of the nozzle 5 noz This reduces the initial force required. As a result, a smaller and cheaper actuation mechanism 30 can be used.

[0122] In addition, the small needle seat area A ns The risk of the needle 20 accidentally lifting off the needle seat 26 in the event of pressure peaks applied from the auxiliary inlet 7 and outlet 12 is reduced.

[0123] If the nozzle 5 is designed to be rotationally symmetrical, its flow cross section A noz is π*(D noz / 2)², where D noz is the minimum inner diameter of the nozzle 5. If the needle seat 26 has a circular shape, the needle seat area A nsz is the area enclosed by the needle seat 26 and corresponds to π*(D ns / 2)², where D ns is the diameter of the needle seat 26 .

[0124] Flow cross section A nozIt can be at least 50 mm². If the nozzle 5 is designed to be rotationally symmetrical, this corresponds to a diameter of 8.0 mm. For example, the flow cross section A of the nozzle 5 noz It can be in the range of 70mm² to 150mm².

[0125] Figure 4 It is shown that in this exemplary embodiment, the end portion of the needle 20 on the needle seat 26 side (seen along the longitudinal direction L) includes a needle tip 21, a first tapered needle portion 22 and a second tapered needle portion 24. The taper angle of the first tapered needle portion 22 is greater than the taper angle of the second tapered needle portion 24. Therefore, an annular edge 23 is formed at the boundary between the first tapered needle portion 22 and the second tapered needle portion 24. When the needle 20 is in its closed position, (only) the annular edge 23 abuts on the needle seat 26.

[0126] The needle 20 may be made of aluminum or an aluminum alloy.

[0127] In the depicted embodiment, the flow resistance of the discharge channel is greater than the flow resistance of the equalization channel 32. This helps to ensure a slow and controlled opening of the injector 1. In particular, the flow cross section A of the pilot valve 50 is pv can be smaller than the flow cross section A of the equalizing channel 32 eq Additionally or alternatively, the flow cross section A of the pilot valve 50 (in its open state) pv Can be smaller than 1.8mm².

[0128] Piston area A of piston 31 P It can be greater than the square of the stroke of the piston rod. In this example, the stroke of the piston rod is the same as the stroke S of the needle 20. For example, the piston area A P It can correspond to at least 8 times, in particular at least 11 times, the square value of the stroke S (A P ≥8*S², especially A P ≥11*S²). Therefore, the stroke S of the axial displacement of the piston 31 corresponds to a large change in the volume of the first cylinder chamber 37 and the second cylinder chamber 38. This helps to ensure a slow movement of the piston 31 and thus the needle 20 during the transition between the open position and the closed position. In addition, by combining this aspect with the aspects explained above, a significant synergistic effect can be obtained, according to which the flow cross section A of the equalizing channel 32 eq The piston area A of the piston 31 can be P Small.

[0129] Additionally or alternatively, the piston area A of the piston 31 P Can be compared with the needle seat area A ns This reduces the effect of the additional lift force on the opening and allows for a smoother opening.

[0130] The nozzle 5 is formed directly downstream of the nozzle inlet 4. The nozzle inlet 4 extends along the longitudinal direction L and tapers towards the nozzle 5. In more detail, the nozzle inlet may extend along a central axis C, as shown in the figures.

[0131] The annular linear portion of the nozzle inlet 4 constitutes a needle seat 26, against which the annular edge 23 abuts when the needle 20 is in its closed position.

[0132] The nozzle inlet 4 is configured to guide fluid supplied at the primary inlet 2 into the nozzle 5. More precisely, the nozzle inlet guides fluid supplied at the primary inlet 2 from the primary inlet chamber 3 into the nozzle 5 (when the needle 20 is in its open position).

[0133] The nozzle inlet 4 may be a conical nozzle inlet. The conical angle of the nozzle inlet 4 is smaller than the conical angle of the first conical needle portion 22 but larger than the conical angle of the second conical needle portion 24 (see, for example, Figure 4 ).

[0134] In the exemplary embodiment, the needle seat 26 and the nozzle 5 are formed as one and the same component, namely as a nozzle insert 27. The nozzle insert 27 is a one-piece component. The nozzle insert is mounted in an insert assembly holder 78. The nozzle insert 27 comprises the upstream nozzle inlet 4 and the nozzle 5. The nozzle insert 27 can be made of a material having a higher hardness than the material of the needle 20.

[0135] For example, the nozzle insert 27 may be made of iron.

[0136] According to another aspect, the length W of the nozzle inlet 4 is greater than the stroke S. For example, the length of the nozzle inlet 4 may correspond to at least 1.8 times the stroke S. This ensures that even when the needle 20 is in its open position, the end portion of the needle 20 protrudes into the nozzle inlet 4. Thus, the needle 20 in its open position contributes to smoothly directing the fluid from the primary inlet chamber 3 into the nozzle inlet 4 and further into the nozzle 5, and to reducing turbulence.

[0137] The distance Z between the nozzle 5 and the needle seat 26 along the longitudinal direction L (and according to the local flow direction) is small. It can be less than 0.8*(A noz / π) 0.5 In other words, the needle seat 26 can be formed directly upstream of the nozzle 5. This is conducive to maintaining the needle seat area A nsz Small and reduces flow resistance.

[0138] Additionally or alternatively, the stroke S may correspond to at least 2*(A noz / π) 0.5 , if the nozzle has a rotationally symmetrical shape, this stroke corresponds to D nozIn particular, the stroke S may correspond to at least 2.8*(A noz / π) 0.5 Thus, the end portion of the needle 20 does not affect the flow of fluid through the nozzle 5 or the needle holder 20 in its open position.

[0139] The injector 1 can be configured so that when the needle 20 is in its open position, the flow cross section A of the nozzle 5 noz The minimum flow cross section between the main inlet 2 and the converging mixing section 6 is formed.

[0140] In the exemplary embodiment, the needle 20 never protrudes downstream of the nozzle 5. In other words, the needle 20 never protrudes into the converging mixing portion 6.

[0141] As an additional feature, the depicted embodiment of the injector 1 provides a check valve function for preventing fluid from flowing from the outlet 12 to the auxiliary inlet 7. The injector 1 provides a check member 80 for closing the fluid connection between the mixing section (more in detail, the converging mixing section 6) and the auxiliary inlet chamber 8. If the injector 1 is in its closed state, the check member 80 abuts on the check valve seat 79 and prevents the fluid from flowing from the outlet 12 to the auxiliary inlet 7. If the injector 1 is in its open state, the fluid is sucked from the auxiliary inlet 7 through the auxiliary inlet chamber 3 and the auxiliary fluid passage 9 into the converging mixing section 6. Thereby, the check member 80 is displaced in the longitudinal direction L and lifted from the check valve seat 79.

[0142] The annular end surface of the cylinder insert 77 and the corresponding abutment area on the top cover 76 are ground flat. The resilient member 90 (a coil spring in this embodiment) biases the cylinder insert 77 against the top cover. Therefore, no significant fluid leakage or pressure propagation occurs directly from the primary inlet chamber 3 to the secondary cylinder chamber 38. The resilient member 90 is arranged in the primary inlet chamber 3 and coaxially with the needle 20. The resilient member is squeezed between the top cover 76 and the insert assembly retainer 78.

[0143] Optionally, a filter 91 is disposed between the primary inlet 2 and the nozzle inlet 4. In an exemplary embodiment, the filter 91 is disposed in the primary inlet chamber 3 around an elastic member 90, wherein the elastic member supports (holds) the filter 91.

[0144] The top cover 76 is removably fixed to the main sleeve 71 by screws. If the top cover 76 is removed, the cylinder insert 76 can be taken out from the main sleeve 71 for maintenance.

[0145] Naturally, the depicted embodiment is only an exemplary embodiment, and the elements may be implemented in other ways and geometries. For example, the end portion of the needle 20 may be formed to have another shape (e.g., a convex cone), the needle seat 26 and the nozzle 5 may be formed as two parts from separate elements, etc.

[0146] Figure 5 An injector 100 according to a second embodiment of the invention is shown. The injector 100 substantially has the same structure as the injector 1. Therefore, only the relevant differences with the injector 1 are explained in the following and the same reference numerals are used for corresponding elements.

[0147] Figure 5 The injector 100 shown in FIG. Figure 1 The injector 1 of EMBODIMENT 1 differs in that the needle 20 has a modified needle tip 121 . Figure 6 yes Figure 5 An enlarged cross section around the needle tip 121.

[0148] In this embodiment, the needle tip 121 includes a middle cylindrical portion 123. In more detail, the needle tip 121 includes a first tapered portion 122, a cylindrical middle portion 123 and a second tapered portion 124. The first tapered portion 122 constitutes the downstream end (in the longitudinal direction L) of the needle tip 121. The second tapered portion 124 is adjacent to the needle rod 25. Viewed along the longitudinal direction L, the middle portion 123 is arranged between the first tapered portion 122 and the second tapered portion 124. The needle rod 25 and the needle tip 121 can be formed integrally. Due to the cylindrical middle portion 123, a large amount of fluid flows out of the nozzle 5 only when the needle 20 is moved away from the abutment with the needle seat 26 by at least a certain distance (the latter is greater than zero). In other words, there is a "dead zone" in which no fluid or at least no large amount of fluid flows through the nozzle 5 when the needle 20 is not in abutment with the needle seat 26 but is displaced by less than a certain distance. This reduces the sensitivity of the ejector 100 to pressure and / or flow pulsations of the fluid at the primary inlet 2 .

[0149] Figure 5 Also shown is a spring resilient member 81 which biases the non-return member 80 .

[0150] Reference numerals list:

[0151] 1 Injector

[0152] 2Main Entrance

[0153] 3Main entrance chamber

[0154] 4 nozzle inlet

[0155] 5 Nozzles

[0156] 6 (Converging) Mixing Section

[0157] 7 Auxiliary entrance

[0158] 8 Auxiliary entrance chamber

[0159] 9 Auxiliary fluid passage

[0160] 10 (Cylindrical) Mixing section

[0161] 11 Diffuser part

[0162] 12Exit

[0163] 20 pins

[0164] 21, 121 pin terminal

[0165] 22 First tapered needle section

[0166] 23 Ring edge

[0167] 24 Second tapered needle section

[0168] 25 needle bar

[0169] 26-pin header

[0170] 27 Nozzle Insert

[0171] 30 Actuating mechanism

[0172] 31 Piston

[0173] 32 equalization channels

[0174] 33 Elastic components

[0175] 35 cylinders

[0176] 36 chamber entrance

[0177] 37 First cylinder chamber

[0178] 38 Second cylinder chamber

[0179] 39 Fluid connection (chamber outlet, part of the discharge channel)

[0180] 40 annular end wall

[0181] 50 pilot valve

[0182] 51 valve seat

[0183] 52 valve components

[0184] 53 Actuator

[0185] 54 first fluid channel (part of the discharge channel)

[0186] 55 Second fluid passage (part of the discharge passage)

[0187] 56, 57 fluid passage (part of the discharge passage)

[0188] 70 Shell

[0189] 71 Main Sleeve

[0190] 72 Main inlet connector

[0191] 73 Auxiliary inlet connector

[0192] 74 first diffuser tube

[0193] 75 Second diffuser pipe 76

[0194] 76 Top Cover

[0195] 77 Cylinder Insert

[0196] 78 Insert assembly holder

[0197] 79 check valve seat

[0198] 80 non-return member

[0199] 81 Elastic components

[0200] 90 elastic member

[0201] 91 filters

[0202] 122 first tapered section

[0203] 123 middle section

[0204] 124 Second tapered section

[0205] C Center axis

[0206] D noz Diameter (of nozzle 5)

[0207] D ns Diameter (of needle seat 26)

[0208] D p Diameter (of piston 31)

[0209] L Longitudinal direction.

Claims

1. An ejector (1; 100), comprising primary entrance (2); secondary entrance (7); and exit (12); a nozzle (5) for spraying the fluid supplied at the primary inlet (2) into the mixing section (6, 10) and for sucking the fluid supplied at the secondary inlet (7) into the mixing section (6, 10); The needle (20) and the needle holder (26) are provided, wherein The needle seat (26) is arranged downstream of the main inlet (2) and upstream of the nozzle (5); as well as An actuating mechanism (30) for moving the needle (20) between an open position and a closed position, wherein the needle (20) is lifted from the needle seat (26) to allow fluid to flow through the needle seat (26), and the needle (20) abuts the needle seat (26) and prevents fluid from flowing through the needle seat (26), wherein the actuating mechanism (30) comprises: a cylinder (35) having a piston (31) connected to the needle (20), wherein when the needle (20) is in its open position, a first cylinder chamber (37) is maximized, and when the needle (20) is in its closed position, a second cylinder chamber (38) is maximized, wherein the first cylinder chamber (37) is in fluid communication with the main inlet (2) via a chamber inlet (36), and wherein the second cylinder chamber (38) is in fluid communication with the first cylinder chamber (37), and a discharge passage (39, 53, 54, 55, 56, 57) having a pilot valve (50), wherein when the pilot valve (50) is in an open state, the second cylinder chamber (38) is in fluid communication with the auxiliary inlet (7) and / or the outlet (12) via the discharge passage (39, 53, 54, 55, 56, 57), Characterized in that the fluid connection between the second cylinder chamber (38) and the first cylinder chamber (37) is provided by an equalizing channel (32), wherein the flow cross section of the equalizing channel (32) is larger than the flow cross section of the discharge channel (39, 53, 54, 55, 56, 57).

2. The injector (1; 100) according to claim 1, characterized in that The piston area, ie the cross-sectional area of ​​the piston, is at least 1000 times the flow cross-section of the equalizing channel (32).

3. The injector (1; 100) according to any one of the preceding claims, characterized in that The needle seat area, ie the cross-sectional area of ​​the needle seat (26) when the needle (20) engages the needle seat (26) in the closed position, is in the range of 1.005 to 1.4 times the flow cross section of the nozzle (26).

4. The injector (1; 100) according to any one of the preceding claims, characterized in that The pilot valve (50) is a solenoid valve.

5. The injector (1; 100) according to any one of the preceding claims, characterized in that The piston area corresponds to at least 20 times the needle seat area.

6. The injector (1; 100) according to any one of the preceding claims, characterized in that The travel (S) of the needle (20) between the closed position and the open position corresponds to at least 2*(A noz / π) 0.5 , where A noz is the flow cross section of the nozzle (5).

7. The injector (1; 100) according to any one of the preceding claims, characterized in that The injector (1; 100) comprises a check valve (79, 80) for preventing fluid from flowing from the outlet (12) to the auxiliary inlet (7).

8. The injector (1; 100) according to any one of the preceding claims, characterized in that The equalizing passage (32) is formed in the piston (31).

9. The injector (1; 100) according to any one of the preceding claims, characterized in that The flow cross section of the equalizing passage (32) is in the range of 1.2 to 2.5 times the flow cross section of the discharge passage (39, 53, 54, 55, 56, 57) when the pilot valve (50) is in the open state.

10. The injector (1; 100) according to any one of the preceding claims, characterized in that A nozzle inlet (4) is formed directly upstream of the nozzle (5), wherein the nozzle inlet (4) tapers toward the nozzle (5), wherein the needle seat (26) is located in the nozzle inlet (4), and wherein the length (W) of the nozzle inlet (4) corresponds to at least 1.8 times the stroke (S) of the needle (20) between the closed position and the open position.

11. The injector (1; 100) according to any one of the preceding claims, characterized in that The injector (1; 100) comprises a resilient member (33) which prevents the piston (31) from minimizing the second cylinder chamber (38).

12. The injector (1; 100) according to any one of the preceding claims, characterized in that The injector (1; 100) is configured such that the opening time of the needle (20) is at least 0.5 s and / or the closing time of the needle (20) is at least 1 s.

13. The injector (1; 100) according to any one of the preceding claims, characterized in that The flow cross section of the nozzle (5) is at least 50 mm².

14. The injector (1; 100) according to any one of the preceding claims, characterized in that The cylinder (35) is formed by a cylinder insert (77) and a top cover (76), wherein a resilient member (81) biases the cylinder insert (77) against the top cover (76).

15. An injector assembly comprising at least two injectors (1; 100) according to any one of claims 1 to 14.

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