Injector having an actuating mechanism with a pilot valve and an equalizing passage between two cylinder chambers

Abstract

The present invention relates to an injector (1; 100) (e.g., for a refrigerant circuit) having a main inlet (2), a secondary inlet (7), an outlet (12), a nozzle (5), and a mixing section (6, 10). The injector (1; 100) includes an actuation mechanism (30) that moves a needle (20) between an open position and a closed position. The actuation mechanism (30) includes a piston (31) in a cylinder (35). 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 secondary inlet (7) and / or the outlet (12) through discharge passages (39, 53, 54, 55, 56, 57) when a pilot valve (50) disposed in the discharge passages (39, 53, 54, 55, 56, 57) is in an open position. To ensure smooth opening and closing, fluid communication between the first cylinder chamber (37) and the second cylinder chamber (38) is provided by an equalization passage (32), the flow cross-sectional area of ​​which is larger than the flow cross-sectional area of ​​the discharge passages (39, 53, 54, 55, 56, 57).

Description

[Technical Field]

[0001] The present invention relates to an injector, for example for a refrigeration circuit with a circulating refrigerant, having a main (fluid) inlet, a secondary (fluid) inlet, a (fluid) outlet, a nozzle, and a mixing section for mixing a fluid supplied at high pressure at the main inlet with a fluid sucked from the secondary inlet. The present invention also relates to an injector assembly having at least two injectors. [Background technology]

[0002] Typically, fluid is supplied to the main inlet by a refrigeration circuit at high pressure. The refrigeration circuit then supplies fluid to the secondary inlet at a lower secondary pressure. The nozzle ejects the fluid received at the main inlet into the mixing section, thereby increasing the flow rate. The fluid received at the secondary inlet is additionally drawn into the mixing section. As a result, the fluid received at the main inlet mixes with the fluid received at the secondary inlet within the mixing section. This combined fluid flow then exits the injector through the outlet. A diffuser is positioned between the mixing section and the outlet. In some applications, the flow of fluid through the nozzle may be blocked, causing the injector to close.

[0003] Examples of injectors are known from WO 2018 / 159320 A1, US Pat. No. 7,841,193 B2, JP 4134918 B2 and EP 1923575 A2.

[0004] U.S. Patent Application Publication No. 2004 / 0040340A1 discloses an injector including a high-pressure refrigerant inlet port, a low-pressure refrigerant inlet port, a nozzle, a mixer, and a diffuser. A pilot valve controls the throttle opening of the nozzle according to the difference between the pressure of refrigerant in a first pressurized chamber and the pressure of intermediate-pressure refrigerant in a second pressurized chamber. The pressure of refrigerant in the first pressurized chamber is the same as the pressure of refrigerant in the high-pressure refrigerant inlet. An orifice is provided in the pilot valve. A passage opening on one side of the high-pressure inlet port and the second pressurized chamber communicate with each other through the orifice. A control valve is in fluid communication with the second pressurized chamber and controls the opening area of ​​a low-pressure refrigerant passage extending between the control valve and the low-pressure refrigerant inlet port.

[0005] The rapid opening and closing of the injector can cause rapid pressure changes (e.g., pressure peaks) within the refrigeration circuit employing the injector, which can lead to damage to components of the refrigeration circuit, and further, to instabilities in the control of the refrigeration system.

[0006] One approach is to control the opening and closing of the injector by a stepper motor, but stepper motors are particularly expensive and therefore not entirely suitable for all applications. Summary of the Invention [Means for solving the problem]

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

[0008] The above-mentioned problems are solved by an injector, for example for a refrigeration circuit with circulating refrigerant.

[0009] Injector: Main (fluid) inlet; secondary (fluid) inlet; and (fluid) outlet; a nozzle for ejecting fluid supplied at the primary inlet into the mixing section for sucking fluid supplied at the secondary inlet into the mixing section; a needle and needle seat, the needle seat being located downstream of the main inlet and upstream of the nozzle (and outlet); and an actuation mechanism for moving the needle between an open position in which the needle is lifted from the needle seat to allow fluid flow over the needle seat and a closed position in which the needle abuts the needle seat to prevent fluid flow over the needle seat; The actuation mechanism includes: a cylinder having a piston connected to a needle, a first cylinder chamber being maximized when the needle is in its open position and a second cylinder chamber being maximized when the needle is in its closed position, the first cylinder chamber being in fluid communication with the main inlet via a chamber inlet, and the second cylinder chamber being in fluid communication with the first cylinder chamber; and A discharge passage having a pilot valve the second cylinder chamber is in fluid communication with the secondary inlet and / or outlet through the discharge passage when the pilot valve is in an open state.

[0010] Fluid communication between the first and second cylinder chambers is provided by an equalization passage.

[0011] The cross-sectional flow area of ​​the equalization passage may be greater than the cross-sectional flow area of ​​the discharge passage.

[0012] The present invention ensures smooth opening and closing of the injector. Pressure peaks due to fast opening and / or closing are reliably avoided. This implementation is cost-effective. For example, no expensive stepper motors are required to ensure smooth opening and closing.

[0013] Additionally, because the needle is connected to the piston, the risk of the needle moving with excessive speed and / or flutter due to external pressure fluctuations, for example fluctuations in the main pressure applied to the main inlet by the external refrigeration circuit, is reduced.

[0014] Fluid from the main inlet can enter the first cylinder chamber through the chamber inlet, thereby filling the first cylinder chamber while the volume of the first cylinder chamber increases.

[0015] The discharge passage is configured to discharge fluid from the second cylinder chamber when the pilot valve is opened, thereby allowing the volume of the second cylinder chamber to be reduced (by displacement of the piston within the cylinder).

[0016] The equalization passage allows fluid to flow from the first cylinder chamber to the second cylinder chamber. The pilot valve is closed to move the needle from the open position to the closed position. When the pilot valve is closed, fluid is not discharged from the second cylinder chamber. The piston is moved to maximize the volume of the second cylinder chamber. More specifically, the second cylinder chamber is filled with fluid from the first cylinder chamber through the equalization passage into the second cylinder chamber, while increasing the volume of the second cylinder chamber. At the same time, the volume of the first cylinder chamber is reduced.

[0017] As noted above, when the needle is in its open position, it allows fluid flow past the needle seat. More specifically, it allows fluid to flow from the main inlet into the nozzle and further into the mixing section. When the needle is in its closed position, fluid flow from the main inlet into the nozzle is prevented. Accordingly, no fluid is drawn into the mixing section from the secondary inlet. Thus, the injector is then closed.

[0018] According to one aspect, when the solenoid valve is in a closed state, the exhaust passage is blocked (closed).

[0019] The chamber inlet, equalization passage, and exhaust passage may be fully integrated within the injector, and they are not constituted by any fluid connections provided by the environment or any external element, and in particular they are not constituted by any fluid connections of the refrigeration circuit employing the injector that are not part of such injector.

[0020] According to one aspect, the actuation mechanism is for moving the needle longitudinally between an open position and a closed position. The cylinder may extend parallel to the longitudinal axis, and the piston may be configured to reciprocate parallel to the longitudinal axis within the cylinder to either 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.

[0021] 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, and 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.

[0022] The piston area is the cross-sectional area of ​​the piston. The piston area can be defined in a plane perpendicular to the longitudinal direction.

[0023] In one embodiment, the piston area is at least 1000 times the cross-sectional flow area of ​​the equalization passage. In particular, the piston area may be at least 1600 times the cross-sectional flow area of ​​the equalization passage.

[0024] If the piston area is increased, displacement of the piston by a given distance corresponds to a larger volume change in the second cylinder chamber, which helps limit the piston velocity.

[0025] During the transition of the needle from the open position to the closed position, fluid flows from the first chamber through the equalization passage to the second chamber. For a given situation, the flow cross-sectional area of ​​the equalization passage limits the flow rate (e.g., measured in ml / s) between the first and second chambers due to its flow resistance. The total volume change of the second chamber during opening increases with increasing piston diameter. By increasing the piston area while the flow cross-sectional area of ​​the equalization passage and the piston stroke remain the same, the closing time is extended. The piston velocity during closing is slower. More specifically, the piston velocity reaches an approximately constant value shortly after the transition from the open position to the closed position begins. This value can be related to the flow rate divided by the piston area.

[0026] Additionally or alternatively, the piston area may be at least 1200 times (in particular at least 1920 times) the cross-sectional flow area of ​​the discharge passage.

[0027] For a given situation, the cross-sectional flow area of ​​the discharge passage limits the fluid discharge rate (e.g., measured in ml / s) that can be discharged from the second chamber through the discharge passage when the pilot valve opens. During the transition from the closed position to the open position, the apparent flow rate of the second chamber can be determined (at least substantially) by the fluid discharge rate and the fluid flow rate entering the equalization passage. The piston velocity can reach a substantially constant value shortly after the transition from the closed position to the second position begins. This value can be related to the apparent flow rate divided by the piston area. If the piston area, and therefore the total volume change of the second chamber required for opening, increases, the opening time will be extended.

[0028] Naturally, if the piston area increases relative to the equalization passage cross-sectional flow area while the discharge passage cross-sectional flow area remains the same, the piston area relative to the discharge passage will likewise increase. And vice versa, if the piston area increases relative to the discharge passage cross-sectional flow area while the equalization passage cross-sectional flow area remains the same, the piston area relative to the equalization passage will likewise increase.

[0029] According to one aspect, the needle seat area, which is the cross-sectional area of ​​the needle seat where the needle engages in the closed position, is in the range of 1.005 to 1.4 times the cross-sectional flow area of ​​the nozzle. The needle seat cross-sectional area is particularly small, thus minimizing the effect of pressure changes at the needle tip as the needle reaches the needle seat and begins to lift off. This facilitates smooth and controlled opening and closing of the injector.

[0030] According to another aspect, the injector may include a housing, which ensures protection of the components inside the housing.

[0031] 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 longitudinally secured to an end of the main sleeve opposite the outlet. The top cover may be removably secured to the main sleeve, which facilitates maintenance.

[0032] According to another aspect, the pilot valve is a solenoid valve. Solenoid valves are particularly inexpensive, reliable, and easy to control. It is not necessary to control the exact opening degree of the pilot valve. The invention ensures smooth opening and closing even when the pilot valve can only be switched between an open and closed state. No additional intermediate states of the pilot valve are required to maintain the needle movement speed below a predetermined threshold.

[0033] In one embodiment, the piston area corresponds to at least 20 times the needle seat area, so that the effect of pressure changes as the needle reaches the needle seat and begins to lift off is at least substantially negligible compared to the effect of fluid flow into and out of the first and second cylinder chambers.

[0034] According to one embodiment, the stroke of the needle between the closed and open positions is at least 2*(A noz / π) 0.5 corresponds to, where A nozis the cross-sectional flow area of ​​the nozzle. When the needle is in its open position, it is fully retracted to ensure low flow resistance to fluid flow from the main inlet to the nozzle, which is beneficial for efficiency.

[0035] According to another aspect, the injector includes a check valve function to prevent fluid flow from the outlet to the secondary inlet, so that elements of the refrigeration circuit employing the injector cannot be damaged by such backflow.

[0036] The first cylinder chamber may be a piston rod-side cylinder chamber, and the second cylinder chamber may be a cylinder chamber in the same cylinder on the other side of the piston.

[0037] According to one embodiment, the needle may be integrally formed with the piston. The needle may simultaneously be the piston rod. The needle is particularly reliable, cost-effective, and lightweight to implement. The needle may include at least one hole that penetrates the piston.

[0038] In one embodiment, the equalization passage is formed (completely) within the piston, which allows for fast and cost-effective production.

[0039] According to another aspect, the flow cross-sectional area of ​​the equalization passage can be in the range of 1.2 to 2.5 times the flow cross-sectional area of ​​the discharge passage when the pilot valve is in its open state. This ensures that the flow resistance of the discharge passage is higher than the flow resistance of the equalization passage. Only a slight pressure drop from the first cylinder chamber to the second cylinder section occurs even during the transition of the needle from the closed position to the open position. The movement speed of the piston and the needle can be precisely controlled and kept low. This further facilitates smooth opening of the injector.

[0040] The cross-sectional area of ​​the discharge passage can be determined by the cross-sectional area of ​​the pilot valve. The pilot valve can be designed to be as small as possible, which reduces costs. Therefore, the cross-sectional area of ​​the equalization passage can be in the range of 1.2 to 2.5 times the cross-sectional area of ​​the pilot valve when the pilot valve is in its open state.

[0041] In one embodiment, the cross-sectional flow area of ​​the chamber inlet is larger than the cross-sectional flow area of ​​the equalization passage. For example, the cross-sectional flow area of ​​the chamber inlet may be at least five times, particularly at least ten times, the cross-sectional flow area of ​​the equalization passage. The amount of fluid leaving the first cylinder chamber via the equalization passage can be easily replenished, particularly if the pilot valve is open. 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., while the volume of the first cylinder chamber is increasing.

[0042] According to one aspect, the needle seat is at least axially fixed relative to the housing, which facilitates precise opening and closing of the injector.

[0043] The nozzle may be disposed within the housing. The nozzle may be at least axially fixed relative to the housing. The nozzle may include a throat portion and a diverging nozzle portion. The throat portion may define a cross-sectional flow area of ​​the nozzle. The diverging nozzle portion may be disposed downstream of the throat. The diverging nozzle portion may be conical, with an inner diameter increasing toward the downstream end of the nozzle. The downstream end of the nozzle may project toward the mixing portion.

[0044] In one embodiment, the nozzle inlet is formed directly upstream of the nozzle, the nozzle inlet tapers towards the nozzle, the needle seat is located within the nozzle inlet, and the length of the nozzle inlet may correspond to at least 1.8 times the stroke of the needle between the closed and open positions, thereby ensuring adequate flow from the fluid supplied at the main inlet into the nozzle and therefore low flow resistance when the injector is in the open state.

[0045] The nozzle inlet and nozzle may be formed as a one-piece component, for example, in a nozzle insert. The nozzle insert may be mounted in an insert assembly holder that is 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.

[0046] According to one aspect, the injector may include an elastic member that acts against minimizing the volume of the second cylinder chamber by the piston. For example, the elastic member urges the piston in a direction that maximizes the volume of the second cylinder chamber. In other words, the elastic member may urge the needle toward its closed position. The elastic member may directly engage with the piston and / or the needle. For example, the elastic member may be provided between the piston and an end wall of the cylinder on the side of the second cylinder chamber. The elastic member facilitates the transition of the needle from its open position to its closed position. The elastic member may include a coil spring.

[0047] In one embodiment, the injector is configured so that the needle opening time is at least 0.5 seconds (e.g., at least 1 second). A long opening time prevents fast pressure changes and therefore reduces the risk of damage in the refrigeration circuit employing the injector.

[0048] Additionally or alternatively, the injector is configured so that the needle closing time is at least 1 s (e.g., at least 2 s). A long closing time prevents rapid pressure changes and therefore reduces the risk of damage in a refrigeration circuit employing the injector.

[0049] In one embodiment, the injector is configured so that the needle moves at a substantially constant velocity over a displacement length corresponding to at least 70% of the stroke during transition from its closed position to its open position (during normal operation), which ensures a controlled, smooth opening and reduces the risk of damage in any refrigeration circuit employing the injector.

[0050] Additionally or alternatively, the injector is configured so that the needle moves at a substantially constant velocity over a displacement length corresponding to at least 70% of the stroke during transition from its open position to its closed position (during normal operation), which ensures a controlled and smooth closure and reduces the risk of damage in any refrigeration circuit employing the injector.

[0051] Nearly constant velocity may mean that the velocity varies by at most 15% during each phase of movement.

[0052] According to another aspect, the nozzle has a flow cross-sectional area of ​​at least 50 mm 2 Therefore, the injector exhibits a high capacity.

[0053] 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 attached within the main sleeve, which allows for easy maintenance.

[0054] According to another aspect, the injector may include a resilient member, for example a spring, in particular a coil spring.

[0055] The elastic member can bias the cylinder insert against the top cover. The second cylinder chamber can be disposed on the side of the top cover. This ensures proper sealing between these elements. This ensures that pressure transmission to the second cylinder chamber is determined by pressure transmission from the first cylinder chamber to the second cylinder chamber via the equalization passage. The risk of large leakage and pressure transmission from the main inlet to the second cylinder chamber bypassing the equalization passage is reduced. The annular end surface of the cylinder insert that abuts against the top cover can be ground flat.

[0056] The resilient member may be wedged between the cylinder insert and a member that is at least axially fixed to the housing, for example, the resilient member may be wedged between the cylinder insert and the insert assembly holder.

[0057] In one embodiment, the injector includes a filter between the main inlet and the needle seat. The filter may be circumferentially disposed about the needle and the needle seat. The filter may be supported by a resilient member.

[0058] According to another aspect, the needle is made of a first material and the needle seat is made of a second material, the second material having a hardness greater 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 (including the needle seat) is made of the second material.

[0059] In one embodiment, the needle tip of the needle includes a mid-section with reduced taper, e.g., a cylindrical mid-section. The cylindrical mid-section creates a "dead band" in the open state, especially in the initial stages of the open state: there is no fluid flow from the nozzle unless the needle is at least a certain distance away from abutting the needle seat. In other words, a significant amount of fluid flow from the nozzle requires the needle to be at least a certain distance away from abutting the needle seat. This reduces the injector's sensitivity to fluid pressure and / or pulsations, especially at the main inlet. Without the dead band, even small pulsations of fluid could lift the needle, which could result in unintended pulsating fluid flow from the nozzle.

[0060] The above mentioned problem is further solved by an injector assembly comprising at least two injectors according to any one of the described embodiments and modifications.

[0061] The injectors may be arranged in parallel.

[0062] In one embodiment, a cross-sectional flow area of ​​a second of the at least two injectors is different from a cross-sectional flow area of ​​a first of the at least two injectors. For example, the cross-sectional flow area of ​​the second injector may be at least 1.2 times the cross-sectional flow area of ​​the first injector. Four different flow rates may be set by closing both the first and second injectors, by opening only the first injector, by opening only the second injector, or by opening both the first and second injectors.

[0063] When reference is made to the cross-sectional flow area of ​​an element (passage, channel, or the like, e.g., a nozzle), this may mean the smallest cross-sectional area of ​​the respective element along the intended direction of flow through the respective element.

[0064] Further features, advantages and possible applications of the present invention emerge from the following description of exemplary embodiments and the accompanying drawings. All features described and / or shown graphically in this specification form the subject of the present invention, either alone or in any desired combination, regardless of how they are combined in the several claims or by reference back to the preceding claims. [Brief explanation of the drawings]

[0065] [Figure 1] 1 shows an embodiment of an injector according to the invention in an open state in a cross-sectional view on a plane extending along the central axis of the injector; [Figure 2] FIG. 2 is an enlarged upper section of FIG. [Figure 3] 3 shows the upper part of the injector of FIG. 2 in a cross-sectional view on a plane also extending along the central axis of the injector but perpendicular to the plane shown in FIGS. 1 and 2. [Figure 4] 2 shows an enlarged cross section of FIG. 1 around the needle seat and nozzle; [Figure 5] 2 shows a second embodiment of an injector according to the invention in the open state in a cross-sectional view on a plane extending along the central axis of the injector; [Figure 6] 5 around the needle tip. DETAILED DESCRIPTION OF THE INVENTION

[0066] One embodiment of an injector 1 according to the present invention is shown in Figure 1. The injector 1 comprises a main (fluid) inlet 2, a secondary (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. A longitudinal direction L is parallel to the central axis C.

[0067] When the injector 1 is in an open state as shown in Figures 1-4, fluid can flow from the first inlet 2 through the nozzle 5, the mixing section (including the tapered mixing section 6 and the cylindrical mixing section 10), and the diffuser section 11 to the fluid outlet 12. In addition, fluid is drawn into the mixing section 6 from the secondary inlet 7. In other words, the fluid drawn in from the secondary inlet 7 combines with the fluid from the main inlet 2 in the tapered mixing section 6. This results in mixing of the fluid from the main inlet 2 and the fluid drawn in from the secondary inlet 7 in the tapered mixing section 6 and in the cylindrical mixing section 10 that continues downstream of the tapered mixing section 6.

[0068] The injector 1 includes a needle valve mechanism having a needle 20 and a needle seat 26 .

[0069] When the needle 20 is in a closed position (not shown), the needle 20 abuts the needle seat 26 and blocks the fluid connection between the main inlet 1 and the nozzle 5. This prevents fluid from the main inlet 1 from entering the nozzle 5 and possibly further into the tapered mixing section 6. This corresponds to the closed state of the injector 1.

[0070] When the needle 20 is in the open position as shown in Figures 1-4, the needle 20 is lifted from the needle seat 26 by a needle stroke S (see Figure 4). This allows fluid 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 (e.g., in the range of 12 mm to 30 mm).

[0071] In this exemplary embodiment, housing 70 of injector 1 includes a main sleeve 71, an upstream top cover 76, a first diffuser tube 74, and a second diffuser tube 75. First diffuser tube 74 and second diffuser tube 75 form at least a downstream portion of diffuser section 11. Housing 70 further includes a main (fluid) inlet connector 72 secured to main sleeve 71 and forming main inlet 2, and a secondary (fluid) inlet connector 73 secured to main sleeve 71 and forming secondary inlet 7.

[0072] The injector 1 further includes an actuation mechanism 30 for moving the needle 20 along the longitudinal direction L between the open and closed positions.

[0073] The actuation mechanism 30 includes a pilot valve 50 and a piston 31. The piston 31 is disposed within a cylinder 35 and can therefore be moved axially (i.e., along a central axis C) within the cylinder 35. The needle 20 is mechanically connected to the piston 31 such that axial movement of the piston 31 within the cylinder 35 is translated into 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 corresponding axial movement of the piston 31. In this embodiment, the needle 20, the piston 31, and the cylinder 35 are all coaxially disposed along the central axis C, and the needle 20 is at least axially fixed to the piston 31. More specifically, the needle 20 and the piston 31 can be integrally formed (in one piece) as shown in FIGS. 1-3 . In other words, the needle 20 (particularly the needle shank 25) also constitutes the piston rod of the piston 31.

[0074] 1-3, the cylinder 35 may be formed by a cylinder insert 77 and a top cover 76. The cylinder insert 77 is disposed inside the main sleeve 71 and directly abuts the top cover 76. The cylinder insert 77 guides the piston 31 and its piston rod (which is the needle 20 in this embodiment).

[0075] The piston 31 is configured to form a first cylinder chamber 37 and a second cylinder chamber 38 within the cylinder 35. The piston 31 may divide the interior of the cylinder 35 into the first cylinder chamber 37 and the second cylinder chamber 38 (along the longitudinal direction L).

[0076] The volume of the first cylinder chamber 37 is maximized (is at its largest) when the needle 20 is in its open position. The volume of the first cylinder chamber 37 is minimized when the needle 20 is in its closed position. The volume of the first cylinder chamber 37 can be reduced to (at least substantially) a minimum volume (small residual volume) when the needle 20 is in its closed position (not shown, corresponding to the lowest possible position of the piston 31 in FIGS. 1-3 ).

[0077] The volume of the second cylinder chamber 38 is maximized (is at its largest) when the needle 20 is in its closed position. The volume of the second cylinder chamber 38 is minimized when the needle 20 is in its open position (corresponding to the highest possible position of the piston 31, as shown in FIGS. 1-3 ). The volume of the second cylinder chamber 38 may be reduced to zero (or at least nearly zero) when the needle 20 is in its open position. However, in the exemplary embodiment, an annular end wall 40 is provided on the surface of the piston 31 facing the second cylinder chamber 38, causing there to still be a residual volume in the second cylinder chamber 38 even when the needle 20 is in its open position. This ensures that the equalization passage 32 is not closed when the needle 20 is in its open position.

[0078] A main (fluid) inlet chamber 3 is formed on the side of the cylinder insert 77 in the longitudinal direction L that deviates from the top cover 76. The main inlet connector 72 opens into the main inlet chamber 3.

[0079] 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 a fluid connection provided between the main inlet chamber 3 and the end of the cylinder 35 in the longitudinal direction L on the side of the needle 20 (the end of the cylinder 35 on the side of the first cylinder chamber 37; i.e., the lower end of the cylinder 35 in FIGS. 1 to 3). The chamber inlet 36 can be formed, for example, in the cylinder insert 77 as at least one hole extending along the longitudinal direction L. In the embodiment shown in FIGS. 1 and 2, four or six such holes are formed in the cylinder insert 77, two of which are visible in FIGS. 1 and 2.

[0080] Furthermore, the other end of the cylinder 35 in the longitudinal direction L (the end of the cylinder 35 on the second cylinder chamber 38 side; i.e., the upper end of the cylinder 35 in FIGS. 1 to 3 ) is in fluid communication with the secondary inlet 7 via a discharge passage. A pilot valve 50 is disposed in the discharge passage. When the pilot valve 50 is in its closed state, the pilot valve 50 blocks (closes) the discharge passage. When the pilot valve 50 is in its open state, the discharge passage is open, and the second cylinder chamber 38 is in fluid communication with the secondary inlet 7. In other words, the discharge passage is formed between the second cylinder chamber 38 on the one hand and the secondary inlet 7 and / or the space in (direct) fluid communication with the secondary inlet 7 on the other hand. In this embodiment, the discharge passage is formed between the second cylinder chamber 38 and the secondary (fluid) inlet chamber 8, which is in direct communication with the secondary inlet 7.

[0081] In a modification (not shown), the second cylinder chamber 38 is in fluid communication with the outlet 12 via the discharge passage when the pilot valve 50 is in an open state. In other words, a discharge passage comprising the solenoid valve 50 is formed between the second cylinder chamber 38 and the fluid outlet 12 and / or a space which, in this case, is in fluid communication with the fluid outlet 12. Naturally, it is also possible to provide a discharge passage having two branches: one branch for fluid communication between the second cylinder chamber 38 and the secondary inlet 7, and another branch for fluid communication between the second cylinder chamber 38 and the fluid outlet 12. Blocking means, for example a check valve, may be employed to prevent fluid flow from the secondary inlet 7 through the discharge passage to the fluid outlet 12.

[0082] 1, the exhaust passage may be formed entirely within the injector 1. Thus, the exhaust passage is incorporated within the injector 1.

[0083] 3, the discharge passage includes a fluid connection 39 between the upper end of the cylinder 35 (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 can be seen in FIG. 3, the chamber outlet 39 may be formed by at least one channel (e.g., two channels) in the top cover 76.

[0084] Additionally, the downstream side of the pilot valve 50 is in fluid communication with the secondary inlet 7. This can be seen in Figures 1 and 2, where the plane of the depicted cross section is perpendicular to the plane shown in Figure 3. In this embodiment, the discharge 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 holder 78. The fluid passage 57 is a generally annular gap between the main sleeve 71 and the insert assembly holder 78. The discharge passage opens into the secondary inlet chamber 8. The secondary inlet connector 73 also opens into the secondary inlet chamber 8. Thus, when the pilot valve 50 is in its open state, the downstream side of the pilot valve 50 is in fluid communication with the secondary inlet 7, and the second cylinder chamber 38 is in fluid communication with the secondary inlet 7.

[0085] Additionally, the second cylinder chamber 38 is in fluid communication with the first cylinder chamber 37. The fluid communication is provided by the equalization passage 32. In this embodiment, the equalization passage 32 comprises a longitudinal bore through the piston 31. The equalization passage 32 may be formed entirely within the injector 1. Thus, the equalization passage 32 is incorporated within the injector 1.

[0086] 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 and closed states. In this embodiment, the pilot valve 50 is a solenoid valve. Thus, the actuator 53 is a solenoid actuator. The pilot valve 50 is part of the injector 1. In particular, the valve seat 51 may be integrally formed with the housing 70 or an insert secured to the housing. In the exemplary embodiment, the valve seat 51 is mounted within the top cover 76.

[0087] In operation, it is assumed that the needle 20 is in its open position and that the pilot valve 50 is initially in its open state. In other words, the injector 1 is initially in its open state.

[0088] During normal operation, fluid is supplied to the main inlet 2 at high main pressure. As a result, high pressure fluid from the main inlet 2 flows through the chamber inlet 36 into the first cylinder chamber 37. The (minimum) cross-sectional flow area A of the chamber inlet 36 is pci is the (minimum) cross-sectional area A of the equalization passage 32 eq For example, the cross-sectional flow area A of the chamber inlet 36 pci is the cross-sectional area A of the equalization passage 32 eq In the exemplary embodiment shown in FIG. pci is the sum of the cross-sectional areas of the holes that form the chamber inlet 36 formed in the cylinder insert 77.

[0089] Due to the chamber inlet 36, the fluid pressure in the first cylinder chamber 37 at least substantially corresponds to the main pressure at the main inlet 2. The fluid pressure in the first cylinder chamber 37 urges the piston 31 toward the top cover 76 (along the longitudinal direction L) and thus the needle 20 toward its open position, against the elastic force provided by the elastic member 33. In the depicted embodiment, the elastic member 33 is a coil spring.

[0090] During normal operation, fluid is supplied to the secondary inlet 7 at a secondary pressure. The secondary pressure is lower 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 secondary pressure. This pressure drop is used to eject fluid from the main inlet chamber 3 through the nozzle 5 into the tapered mixing section 6 when the needle 20 is in its open position. The fluid ejected from the nozzle 5 has a high velocity. Ejection through the nozzle 5 creates a pressure drop from the main inlet chamber 3 to the tapered mixing section 6. Furthermore, 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 secondary inlet 7 is sucked through the secondary inlet chamber 8 and enters the tapered mixing section 6 through the secondary fluid passage 9. The fluid ejected by the nozzle 5 from the main inlet 2 and the fluid sucked through the secondary inlet chamber 8 mix in the tapered mixing section 6 and the cylindrical mixing section 10.

[0091] As stated above, it is assumed that the pilot valve 50 is initially in its open state. A small fluid flow occurs from the first cylinder chamber 37 to the second cylinder chamber 38 via the equalization passage 32. Additionally, fluid flows from the second cylinder chamber 38 to the secondary inlet chamber 8 via the discharge passage because the pilot valve 50 is in its open state. Therefore, there is a small pressure drop from the first cylinder chamber 37 to the second cylinder chamber 38 that is sufficient to keep the needle 20 in an open position. This pressure drop is high enough to hold the piston 31 against the top cover 76 against the restoring force of the elastic element 33.

[0092] Cross-sectional flow area A of the equalization passage 32 eq is relatively small. This is 10mm 2 Less than, for example, 0.5 mm 2 ~4mm 2 Additionally or alternatively, the length L of the equalization passage 32 (along the direction of flow therethrough) may be in the range eq The value corresponding to the square of is the flow cross-sectional area A of the equalization passage 32. eq (L eq 2 ≧15*A eq) The equalization passage 32 presents a significant flow resistance.

[0093] If the equalization passage 32 has a cylindrical shape, its cross-sectional flow area A eq is π*(D eq / 2) 2 where D eq is the diameter of the equalization passage 32.

[0094] Generally, the cross-sectional flow area A of the equalization passage 32 eq is the (minimum) cross-sectional area A of the discharge passage dp or more (when the pilot valve 50 is in its open state).

[0095] 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 may at least substantially correspond to the main pressure). The intermediate pressure is higher than the secondary pressure. The exact value of the intermediate pressure depends, inter alia, on the flow resistance and therefore on the flow cross-sectional area A of the equalization passage 32. eq It depends not only on the flow resistance but also on the cross-sectional area A of the discharge passage. dp and also ratio A eq / A dp Depends on.

[0096] Cross-sectional flow area A of the equalization passage 32 eq is the cross-sectional area of ​​the discharge passage A dp If it is significantly smaller than (A eq / A dp <<1), the flow resistance of the discharge passage is significantly smaller than the flow resistance of the equalization passage 32. When the pilot valve 50 is in its open state, fluid can be discharged almost unimpeded from the second cylinder chamber 38 through the discharge passage into the secondary inlet chamber 8. The intermediate pressure in the second cylinder chamber 38 is almost as low as the secondary pressure when the pilot valve 50 is in its open state.

[0097] However, according to one aspect of the present disclosure, the cross-sectional flow area A of the equalization passage 32 eq is the cross-sectional area of ​​the discharge passage A dp It may be larger than (A eq / Adp >1). In particular, the cross-sectional area A of the equalization passage 32 eq is the cross-sectional area of ​​the discharge passage A dp The range can be 1.2 to 2.5 times (1.2*A dp ≦A eq ≦2.5*A dp ). The flow resistance of the equalization passage 32 is smaller than the flow resistance of the discharge passage. However, the pressure drop from the first cylinder chamber 37 to the second cylinder chamber 38 is smaller in this case. Nevertheless, the intermediate pressure in the second cylinder chamber 38 is lower than the pressure in the first cylinder chamber 37 when the pilot valve 50 is in its open state. In other words, there is nevertheless a small pressure drop. This small pressure drop still exists due to the continuous discharge of fluid from the second cylinder chamber 38 due to the flow resistance exerted by the equalization passage 32. For example, the injector 1 can be configured such that the pressure drop from the first cylinder chamber 37 to the second cylinder chamber 38 (i.e., the pressure drop along the equalization passage 32) during normal operation is less than 10 bar, in particular less than 3 bar, provided that the pilot valve 50 is open for at least 0.2 s. This ensures a smooth transition of the needle 20 from its closed position 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.

[0098] The injector 1 may therefore be configured such that the opening time of the needle 20 is at least 0.5 s, in particular at least 1 s, during normal operation. The opening time may be the time required for movement of the needle 20 from its closed position to its open position during normal operation.

[0099] (Minimum) cross-sectional flow area A of the discharge passage dp is the cross-sectional flow area A of the pilot valve 50 when the pilot valve 50 is in its open state. pv It can correspond to.

[0100] Starting with a situation in which the needle 20 is in its open position and the pilot valve 50 is open, the intermediate pressure is lower than the pressure in the first cylinder chamber 37 as long as the pilot valve 50 remains open. The needle 20 is kept in its open position as long as the pilot valve 50 remains open. The injector 1 is configured so that in this situation the force on the piston 31 resulting from 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.

[0101] Now, let us assume that the pilot valve 50 is closed in this situation. No further fluid can be discharged from the second cylinder chamber 38 to the secondary inlet chamber 8. Because the equalization passage 32 remains open, the pressure in the second cylinder chamber 38 increases toward the pressure in the first cylinder chamber 37 (which may at least substantially correspond to the main pressure). In addition, the elastic member 33 urges the piston 31 away from the top cover 76. The piston 31 begins to move along the longitudinal direction L toward the needle seat 26. Thus, the needle 20 begins to move along the longitudinal direction L toward the needle seat 26 (i.e., toward its closed position).

[0102] Cross-sectional flow area A of the equalization passage 32 eq is the piston area A of piston 31 P It is small compared to the piston area A P is the cross-sectional flow area A of the equalization passage 32 eq This limits the speed at which the piston 31 moves.

[0103] This ensures a smooth transition of the needle 20 from its open position 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 actuating 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.

[0104] The injector 1 may be configured such that the closing time of the needle 20 is at least 1 s (in particular at least 2 s) during normal operation. The closing time may be the time required for the needle 20 to move from its open position to its closed position during normal operation.

[0105] For example, piston area A P is 2000mm 2 ~10,000mm 2 The range may be:

[0106] If the piston 31 has a rotationally symmetric basic shape, its flow cross-sectional area A p is π*(D p / 2) 2 where D p is the diameter of the piston 31.

[0107] At the end of the transition of the injector 1 from its open state to its closed state, the needle 20 abuts the needle seat 26. Fluid connection from the main inlet chamber 3 to the nozzle 5 (and hence from the main inlet 2 to the nozzle 5) is blocked. No further fluid is ejected by the nozzle 5. Therefore, no further fluid is sucked into the tapered mixing section 6 from the secondary inlet 7.

[0108] To bring the injector 1 from its closed state to its open state again, the pilot valve 50 is reopened. Fluid is discharged from the second cylinder chamber 38 into the secondary inlet chamber 8, and the pressure in the second cylinder chamber 38 drops towards the aforementioned 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 along the longitudinal direction L such that the needle 20 is retracted from the needle seat 26 towards the open position.

[0109] Cross-sectional area A of needle seat 26 nsz (Needle seat area A ns ) is the (minimum) cross-sectional area A of the nozzle 5 noz In particular, the needle seat area A nsz is the cross-sectional area A of nozzle 5 nozThis allows for a needle 20 with a small diameter. Therefore, the flow resistance of the fluid flowing from the main inlet 2 to the nozzle 5 is particularly small when the needle 20 is in its open position. Furthermore, the relatively small needle seat area A nsz ensures a smooth and precise initiation of the transition of the needle 20 from its closed position to its open position.

[0110] Typically, an increased initial force is required to initiate the transition from the closed position (i.e., from retracting the needle 20 from the closed position, and in particular from abutment with the needle seat 26) to the open position. The force required for further retraction of 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 is the cross-sectional area A of nozzle 5 noz , as close as possible to the initial force required. As a result, a smaller and less expensive actuation mechanism 30 can be used.

[0111] Furthermore, the small needle seat area A ns reduces the risk of unintentional lifting of the needle 20 from the needle seat 26 in the event of pressure peaks applied from the secondary inlet 7 and outlet 12 .

[0112] If the nozzle 5 is rotationally symmetric, its flow cross-sectional area 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 π*(D ns / 2) 2 where D corresponds to ns is the diameter of the needle seat 26.

[0113] Flow cross-sectional area A noz is at least 50mm2 This corresponds to a diameter of 8.0 mm if the nozzle 5 is rotationally symmetrical. For example, the cross-sectional flow area A of the nozzle 5 noz is 70mm 2 ~150mm 2 The range may be:

[0114] 4 shows that in this exemplary embodiment, the end portion of the needle 20 facing the needle seat 26, as viewed along the longitudinal direction L, includes a needle tip 21, a first conical needle section 22, and a second conical needle section 24. The taper angle of the first conical needle section 22 is greater than the taper angle of the second conical needle section 24. Thus, an annular edge 23 is formed at the interface between the first conical needle section 22 and the second conical needle section 24. Only the annular edge 23 rests on the needle seat 26 when the needle 20 is in its closed position.

[0115] The needle 20 may be made of aluminum or an aluminum alloy.

[0116] In the depicted embodiment, the flow resistance of the discharge passage is greater than the flow resistance of the equalization passage 32. This helps ensure a gradual and controlled opening of the injector 1. In particular, the flow cross-sectional area A of the pilot valve 50 pv is the cross-sectional area A of the equalization passage 32 eq Additionally or alternatively, the cross-sectional flow area A of the pilot valve 50 (in its open state) pv is 1.8mm 2 It may be less than.

[0117] Piston area A of piston 31 P may be greater than the square of the piston rod stroke. In this example, the piston rod stroke is equal to the stroke S of the needle 20. For example, the piston area A P corresponds to at least 8 times (especially at least 11 times) the square of the stroke S (AP≧8*S 2 , especially A P ≧11*S 2) Thus, the axial displacement of the piston 31 through the stroke S corresponds to a large change in the volume of the first cylinder chamber 37 and the volume of the second cylinder chamber 38. This helps to ensure a gradual movement of the piston 31, and thus the needle 20, during the transition between the open and closed positions. Furthermore, clear synergistic effects can be obtained by combining this embodiment with the embodiment described above, whereby the flow cross-sectional area A of the equalization passage 32 eq is the piston area A of piston 31 P may be small compared to

[0118] Additionally or alternatively, the piston area A of the piston 31 P is the needle seat area A ns This reduces the effect of the additional lifting force on the opening, resulting in a smoother opening.

[0119] The nozzle 5 is formed directly downstream of the nozzle inlet 4. The nozzle inlet 4 extends in a longitudinal direction L and tapers towards the nozzle 5. More specifically, the nozzle inlet 4 may extend along a central axis C as shown in the accompanying drawings.

[0120] The annular line of the nozzle inlet 4, onto which the annular edge 23 abuts when the needle 20 is in its closed position, defines the needle seat 26.

[0121] The nozzle inlet 4 is configured to direct the fluid provided at the main inlet 2 into the nozzle 5. More precisely, the nozzle inlet 4 directs the fluid provided at the main inlet 2 from the main inlet chamber 3 into the nozzle 5 (when the needle 20 is in its open position).

[0122] The nozzle inlet 4 may be a conical nozzle inlet, the taper angle of which is less than the taper angle of the first conical needle portion 22 but greater than the taper angle of the second conical needle portion 24 (see, for example, FIG. 4).

[0123] In this exemplary embodiment, the needle seat 26 and the nozzle 5 are formed in the same component, i.e., the nozzle insert 27. The nozzle insert 27 is a one-piece component. The nozzle insert 27 is mounted in an insert assembly holder 78. The nozzle insert 27 includes the upstream nozzle inlet 4 and the nozzle 5. The nozzle insert 27 may be made of a material that has a higher hardness than the material of the needle 20.

[0124] For example, the nozzle insert 27 may be made of iron.

[0125] According to another embodiment, the length W of the nozzle inlet 4 is longer 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 an end portion of the needle 20 still protrudes into the nozzle inlet 4 even when the needle 20 is in its open position. Thus, in its open position, the needle 20 helps to smoothly guide the fluid from the main inlet chamber 3 into the nozzle inlet 4 and further into the nozzle 5 and to reduce turbulence.

[0126] The distance Z between the nozzle 5 and the needle seat 26 along the longitudinal direction L (due to the local flow direction) is small. This is 0.8*(A noz / π) 0.5 In other words, the needle seat 26 can be formed directly upstream of the nozzle 5. This allows the needle seat area A nsz This facilitates keeping the flow resistance low and reducing the flow resistance.

[0127] Additionally or alternatively, the stroke S is at least 2*(A noz / π) 0.5 (If the nozzle has a rotationally symmetric shape, D noz In particular, the stroke S may correspond to at least 2.8*(A noz / π) 0.5 As a result, the end portion of the needle 20 does not impede fluid flow through the nozzle 5 or needle seat 20 in its open position.

[0128] The injector 1 has a cross-sectional flow area A of the nozzle 5 when the needle 20 is in its open position. noz may be configured to define the smallest cross-sectional flow area between the main inlet 2 and the tapered mixer section 6 .

[0129] In the exemplary embodiment, the needle 20 does not protrude downstream of the nozzle 5. In other words, the needle 20 never protrudes into the tapered mixing section 6.

[0130] As an additional feature, the depicted embodiment of injector 1 provides check valve functionality to prevent fluid flow from the outlet 12 to the secondary inlet 7. The injector 1 provides a check member 80 to close the fluid connection between the mixing section (more particularly the tapered mixing section 6) and the secondary inlet chamber 8. When the injector 1 is in its closed state, the check member 80 abuts against the check valve seat 79 and prevents fluid flow from the outlet 12 to the secondary inlet 7. When the injector 1 is in its open state, fluid is drawn from the secondary inlet 7 through the secondary inlet chamber 3 and the secondary fluid passage 9 into the tapered mixing section 6. Accordingly, the check member 80 is moved along the longitudinal direction L and lifts off the check valve seat 79.

[0131] The annular end surface of the cylinder insert 77 and the corresponding abutment area on the top cover 76 are ground flat. An elastic member 90 (which is a coil spring in this embodiment) biases the cylinder insert 77 against the top cover. Therefore, no significant fluid leakage or pressure transmission can occur directly from the main inlet chamber 3 to the second cylinder chamber 38. The elastic member 90 is disposed within the main inlet chamber 3 and is coaxial with the needle 20. The elastic member 90 is pressed between the top cover 76 and the insert assembly holder 78.

[0132] Optionally, a filter 91 is provided between the main inlet 2 and the nozzle inlet 4. In some exemplary embodiments, the filter 91 is provided within the main inlet chamber 3 around a resilient member 90, where the resilient member supports (assists) the filter 91.

[0133] The top cover 76 is removably secured to the main sleeve 71 by screws. Once the top cover 76 is removed, the cylinder insert 76 can be taken out of the main sleeve 71 for maintenance.

[0134] Of course, the depicted embodiment is only an exemplary embodiment, and these elements can be implemented in other ways and geometries: for example, the end portion of the needle 20 can be formed with a different shape (e.g., a convex taper), the needle seat 26 and the nozzle 5 can be formed by two separate elements, etc.

[0135] Figure 5 shows an injector 100 according to a second embodiment of the invention. Injector 100 is generally of the same construction as injector 1. Therefore, only significant differences from injector 1 will be described below, and the same reference numerals will be used for corresponding elements.

[0136] The injector 100 shown in Figure 5 differs from the injector 1 of Figure 1 in that the needle 20 has a modified needle tip 121. Figure 6 is an enlarged section of Figure 5 around the needle tip 121.

[0137] In this embodiment, the needle tip 121 includes an intermediate cylindrical portion 123. More specifically, the needle tip 121 includes a first tapered portion 122, a cylindrical intermediate 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 shank 25. When viewed along the longitudinal direction L, the intermediate portion 123 is located between the first tapered portion 122 and the second tapered portion 124. The needle shank 25 and the needle tip 121 may be integrally formed. Due to the cylindrical intermediate portion 123, mass fluid flow from the nozzle 5 occurs only when the needle 20 is at least a certain distance (greater than zero) from abutting the needle seat 26. In other words, there is a "dead zone" where no fluid flow, or at least no significant fluid flow, occurs through the nozzle 5 when the needle 20 is not in abutment with the needle seat 26 but is spaced less than a certain distance away. This reduces the sensitivity of the injector 100 to pressure and / or pulsations of fluid at the main inlet 2.

[0138] FIG. 5 also shows a return spring member 81 that biases the check member 80 . [Explanation of symbols]

[0139] 1 injector 2 Main entrance 3 Main entrance room 4 Nozzle inlet 5 nozzles 6 (Tapered) Mixing Section 7 Secondary entrance 8 Secondary entrance room 9 Secondary fluid passage 10 (cylindrical) mixing section 11 Diffuser section 12 Exit 20 needles 21,121 Needle Tip 22 first conical needle portion 23 Circular margin 24 Second conical needle part 25 needle pattern 26 Needle seat 27 Nozzle Insert 30 Operating mechanism 31 Piston 32 Equalization Passage 33 Elastic member 35 cylinders 36 Room entrance 37 First cylinder chamber 38 Second cylinder chamber 39 Fluid connection (chamber outlet, part of exhaust passage) 40 Annular end wall 50 Pilot valve 51 Valve seat 52 Valve member 53 Actuator 54 First fluid passage (part of discharge passage) 55 Second fluid passage (part of discharge passage) 56, 57 Fluid passage (part of discharge passage) 70 Case 71 Main sleeve 72 Main inlet connector 73 Secondary inlet connector 74 First Diffuser Tube 75 Second Diffuser Tube 76 Top lid 77 Cylinder Insert 78 Insert Assembly Holder 79 Check valve seat 80 check member 81 Elastic member 90 Elastic member 91 filters 122 First tapered section 123 Mid Section 124 Second tapered section C center axis D noz Diameter (Nozzle 5) D ns Diameter (of needle seat 26) D p Diameter (of piston 31) L Longitudinal direction

Claims

1. An injector (1;100) comprising: a main inlet (2); a secondary inlet (7); and an outlet (12); a nozzle (5) for ejecting the fluid supplied at the main inlet (2) into the mixing section (6, 10) for sucking the fluid supplied at the secondary inlet (7) into the mixing section (6, 10); a needle (20) and a needle seat (26), said needle seat (26) being arranged downstream of said main inlet (2) and upstream of said nozzle (5); and an actuation mechanism (30) for moving the needle (20) between an open position in which the needle (20) is lifted from the needle seat (26) to allow fluid flow over the needle seat (26) and a closed position in which the needle (20) abuts the needle seat (26) to prevent fluid flow over the needle seat (26); and the actuation mechanism (30) comprises: a cylinder (35) having a piston (31) connected to the needle (20), a first cylinder chamber (37) being maximized when the needle (20) is in its open position, a second cylinder chamber (38) being maximized when the needle (20) is in its closed position, the first cylinder chamber (37) being in fluid communication with the main inlet (2) via a chamber inlet (36), and the second cylinder chamber (38) being 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 the second cylinder chamber (38) is in fluid communication with the secondary inlet (7) and / or the outlet (12) via the discharge passage (39, 53, 54, 55, 56, 57) when the pilot valve (50) is in an open state; Injector (1; 100) comprising: the fluid communication between the first cylinder chamber (37) and the second cylinder chamber (38) is provided by an equalization passage (32); An injector (1; 100) wherein the cross-sectional flow area of ​​said equalization passage (32) is greater than the cross-sectional flow area of ​​said discharge passages (39, 53, 54, 55, 56, 57).

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

3. 3. The injector (1; 100) according to claim 1, wherein a needle seat area, which is a cross-sectional area of ​​the needle seat (26) where the needle (20) engages with the needle seat (26) in the closed position, is in the range of 1.005 to 1.4 times the flow cross-sectional area of ​​the nozzle (26).

4. Injector (1; 100) according to any one of claims 1 to 3, characterized in that the pilot valve (50) is a solenoid valve.

5. 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 stroke (S) of the needle (20) between the closed and open positions is at least 2*(A ｎｏｚ / π) ０．５ where A corresponds to ｎｏｚ 6. Injector (1; 100) according to any one of claims 1 to 5, characterized in that: is the cross-sectional flow area of ​​the nozzle (5).

7. 7. The injector (1; 100) according to any one of claims 1 to 6, characterized in that the injector (1; 100) comprises a check valve (79, 80) for preventing fluid flow from the outlet (12) to the secondary inlet (7).

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

9. An injector (1; 100) according to any one of claims 1 to 8, characterized in that the flow cross-sectional area of ​​the equalization passage (32) is in the range of 1.2 to 2.5 times the flow cross-sectional area of ​​the discharge passage (39, 53, 54, 55, 56, 57) when the pilot valve (50) is in an open state.

10. 10. The injector (1; 100) according to any one of claims 1 to 9, characterized in that the nozzle inlet (4) is formed directly upstream of the nozzle (5), the nozzle inlet (4) tapering in the direction of the nozzle (5), the needle seat (26) being arranged in the nozzle inlet (4), and the length (W) of the nozzle inlet (4) corresponding 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 claims 1 to 10, characterized in that it includes an elastic member (33) that acts against the minimization of the second cylinder chamber (38) by the piston (31).

12. 12. The injector (1; 100) according to any one of claims 1 to 11, characterized in that the injector (1; 100) is configured so that the opening time of the needle (20) is at least 0.5 s and / or so that the closing time of the needle (20) is at least 1 s.

13. The flow cross-sectional area of ​​the nozzle (5) is at least 50 mm ２ 13. Injector (1; 100) according to any one of claims 1 to 12, characterized in that:

14. 14. An injector (1; 100) according to any one of claims 1 to 13, characterized in that the cylinder (35) is formed by a cylinder insert (77) and a top cover (76), and an elastic member (81) biases the cylinder insert (77) into abutment against the top cover (76).

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

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