KR102127048B1 - Injector for reductant delivery unit having fluid volume reduction assembly - Google Patents

Abstract

A fluid injector, a fluid inlet, a fluid outlet, a fluid path from the fluid inlet to the fluid outlet; tube; A filter disposed within the tube proximate the fluid inlet; And a calibration filter tube disposed downstream of the filter. The calibration filter tube includes a first end portion adjacent the filter, and an axial through bore, the through bore defining at least a portion of the fluid path through the fluid injector. An actuator unit is disposed in the fluid injector and engages the second end of the calibration filter tube. A valve assembly is operatively coupled to the actuator unit. The position of the calibration filter tube in the tube sets the opening force of the valve assembly. The cap member has sidewalls defining an interior space for receiving the filter, and the sidewalls are attached in contact with the first end of the calibration filter tube.

Description

INJECTOR FOR REDUCTANT DELIVERY UNIT HAVING FLUID VOLUME REDUCTION ASSEMBLY for reducing agent delivery units with fluid volume reduction assemblies

Cross reference to related applications

This application is filed in ___ and has an American patent application entitled "INJECTOR FOR REDUCTANT DELIVERY UNIT HAVING REDUCED FLUID VOLUME" (Agent No. 2017P03658US); United States patent application ___ filed ___ and entitled "SEAL MEMBER FOR REDUCTANT DELIVERY UNIT" (Agent No. 2017P03660US); And US Patent Application ___ (Agent Management No. 2017P03659US) filed in ___ and entitled "INJECTOR FOR REDUCTANT DELIVERY UNIT HAVING FLUID VOLUME REDUCTION ASSEMBLY". The entire contents of the above application documents are incorporated herein.

Technical field

The present invention relates generally to a fluid injector of a reductant delivery unit (RDU), and more particularly to a robust RDU fluid injector for non-purge applications.

In Europe and North America, emission regulations are new to lean combustion technologies, particularly in lean combustion technologies such as stratified-charge spark ignition engines (usually direct injection) and compressed ignition (diesel) engines operating in lean and extremely lean conditions. We are promoting the implementation of a processing system. Lean combustion engines exhibit a high level of nitrogen oxide emissions (NOx), which is difficult to handle in an oxygen-rich exhaust gas environment characteristic of lean combustion. An exhaust gas post-treatment technology for treating NOx in this state is currently being developed.

One of these techniques includes a catalyst that promotes the reaction of ammonia (NH ₃ ) and exhaust gas nitrogen oxides (NOx) to produce nitrogen (N ₂ ) and water (H ₂ O). This technique is called Selective Catalytic Reduction (SCR). Because ammonia is difficult to handle in the automotive environment in its pure form, this system uses a diesel exhaust fluid (DEF) and/or is generally liquid-aqueous with urea (CO(NH ₂ ) ₂ ) at a concentration of 32%. It is common to use urea solutions. This solution is called AUS-32 and is also known by the commercial name AdBlue. The reducing agent solution is typically delivered to the hot exhaust gas stream using an injector and converted to ammonia before entering the catalyst. More specifically, the solution is delivered to a hot exhaust stream and is thermally decomposed with ammonia and isocyanoic acid (HNCO) or converted to ammonia in the exhaust gas after thermal decomposition. Isocyanic acid is hydrolyzed with water present in the exhaust gas to be converted to ammonia and carbon dioxide (CO ₂ ), and ammonia produced by thermal decomposition and hydrolysis undergoes catalytic reaction with nitrogen oxide as described above.

AUS-32 or AdBlue has a freezing point of -11°C, so it is expected that the system will freeze in cold climates. Because this fluid is aqueous, volumetric expansion occurs after it transitions to a solid state upon freezing. The expanding solid can exert considerable force on any closed volume, such as an injector. Since this expansion can damage the injection unit, other SCR strategies exist to address the expansion of the reducing agent.

There are two known SCR system strategies in the market: purge system and non-purge system. In a purge SCR system, the reducing agent urea and/or DEF solution is purged from the RDU when the vehicle engine is turned off. In a non-purge SCR system, the reducing agent remains in the RDU throughout the life of the vehicle. During normal operation of a non-purge SCR system, the RDU injector operates at a temperature higher than the freezing point of the reducing agent so that the reducing agent in the RDU remains liquid. However, in a non-fuzzy SCR system, when the vehicle engine is turned off, the RDU injector is filled with the reductant as it is, and the RDU injector may be damaged due to expansion of the reductant under freezing conditions.

The exemplary embodiment overcomes the drawbacks found in existing RDU fluid injectors and provides an improved fluid injector for non-purge SCR systems where the adverse effect is reduced by the RDU being at a temperature below the freezing point of the reducing agent. According to an exemplary embodiment, the RDU has a fluid injector having a fluid inlet disposed at a first end of the fluid injector to receive a reducing agent and a fluid outlet disposed at a second end of the fluid injector to discharge the reducing agent. Includes. The fluid injector forms a fluid path for the reducing agent from the fluid inlet to the fluid outlet. The fluid injector comprises: a tube member having an end disposed at or near the fluid inlet of the fluid injector and configured to pass a reducing agent along the fluid path; A filter disposed within the tube member proximate the fluid inlet of the fluid injector; And a calibration filter tube disposed in the tube member downstream of the filter with respect to the flow direction of the reducing agent along the fluid path from the fluid inlet to the fluid outlet of the fluid injector, wherein the calibration filter tube comprises: It has a first end portion and a second end adjacent to the filter, further comprising a bore formed axially through the calibration filter tube, the bore forming at least a portion of the fluid path through the fluid injector. An actuator unit is disposed in the fluid injector downstream of the calibration filter tube, and the actuator unit engages the second end of the calibration filter tube. A valve assembly is operatively coupled to the actuator unit, and the position of the calibration filter tube in the tube member at least partially establishes an opening force against the valve assembly. The volume reducing member has a bore through which the orthodontic filter tube extends, and the volume reducing member occupies a space between the outer surface of the orthodontic filter tube and the inner surface of the tube member. In one exemplary embodiment, the filter, the calibration filter tube and the volume reduction member form a unitary sub-assembly component of the fluid injector.

In one exemplary embodiment, the volume reducing member is formed of a compressible material, the compressible material being one of a rubber composition and a closed cell foam.

In one exemplary embodiment, the volume reducing member includes a side wall, and the side wall of the volume reducing member forms a undulating in a direction along the longitudinal axis of the fluid injector.

The fluid injector may further include a cap member including a side wall forming an inner space in which the filter is disposed, the side wall contacting the first end of the calibration filter tube. The first end portion of the calibration filter tube is disposed in the inner space of the cap member. The first end portion of the calibration filter tube is attached to the side wall of the cap member such that the calibration filter tube, the cap member, the volume reduction member and the filter form an integral sub-assembly component of the fluid injector. Can.

The actuator unit may include a pole piece disposed in a fixed position in the fluid injector and having a bore formed axially therethrough, and an armature movably positioned in the fluid injector and having a pocket. The actuator unit may further include a coil disposed proximate to the pole piece and the armature, and a spring disposed at least partially within the pocket of the armature. In one exemplary embodiment, the calibration filter tube is disposed in the bore of the pole piece such that the second end of the calibration filter tube contacts the spring, and the spring is the armature when there is no current passing through the coil. Deflects away from the pole piece, placing the valve assembly in a closed position to prevent the reducing agent from passing through the fluid outlet.

The calibration filter tube includes a second part extending axially from the first end part of the calibration filter tube, and a third part disposed between the second end and the second part of the calibration filter tube. do. The volume reduction member is disposed around the second portion, the third portion is disposed within the bore of the pole piece, and the downstream end of the volume reduction member is along the fluid path to the direction of the reducing agent relative to the flow direction of the reducing agent. Adjacent to the upstream end.

The outer diameter of the second portion of the calibration filter tube may be greater than the outer diameter of the third portion of the calibration filter tube.

In another exemplary embodiment, the RDU fluid injector has a fluid inlet disposed at a first end and configured to receive fluid, and a fluid outlet disposed at a second end of the fluid injector to discharge the fluid, wherein A fluid injector forms a fluid path of the fluid from the fluid inlet to the fluid outlet. The tube member has an end disposed at or near the fluid inlet of the fluid injector, and the tube member is configured to pass fluid along the fluid path. A filter is disposed in the tube member proximate the fluid inlet of the fluid injector. A calibration filter tube is disposed within the tube member downstream of the filter with respect to the flow direction of fluid along the fluid path from the fluid inlet of the fluid injector to the fluid outlet. The calibration filter tube has a first end portion proximate the filter, a second end, and a bore formed axially through the calibration filter tube, the bore providing at least a portion of the fluid path through the fluid injector. To form. An actuator unit is disposed in the fluid injector downstream of the calibration filter tube, and the actuator unit engages the second end of the calibration filter tube. A valve assembly is operatively coupled to the actuator unit, and the position of the calibration filter tube in the tube member sets an opposing opening force of the valve assembly. The fluid injector further includes a cap member having side walls forming an interior space in which the filter is disposed. In one exemplary embodiment, the sidewall is attached in contact with the cap end, the filter, and the calibration filter tube in contact with the first end of the calibration filter tube to form a single sub-assembly component of the fluid injector.

Aspects of the invention will be described in detail below with reference to exemplary embodiments in connection with the drawings.
1 is a side cross-sectional view of an RDU for a non-purge SCR system according to an exemplary embodiment;
2 is a side cross-sectional view of the fluid injector of the RDU of FIG. 1;
3 is an enlarged cross-sectional view of an inlet portion of the fluid injector of the RDU of FIG. 1 according to an exemplary embodiment;
4 is an exploded perspective view of components of the fluid injector of the RDU of FIG. 1 according to an exemplary embodiment;
5 is an enlarged cross-sectional view of an outlet portion of the fluid injector of the RDU of FIG. 1 according to an exemplary embodiment;
Fig. 6 is an enlarged sectional view of an inlet portion of the fluid injector of the RDU of Fig. 1 according to another exemplary embodiment;
7 is an exploded perspective view of the components of the fluid injector of FIG. 6;
8 is a cross-sectional view of the component of FIG. 6;
Fig. 9 is an enlarged sectional view of an inlet portion of the fluid injector of the RDU of Fig. 1 according to another exemplary embodiment;
10 is a cross-sectional view of the components of the fluid injector of FIG. 9;
11 is a perspective view of components of the fluid injector of FIG. 9;
12 is a cross-sectional view of an inlet portion of the fluid injector of the RDU of FIG. 1 according to another exemplary embodiment;
13 is a cross-sectional view of the integral component of the fluid injector of FIG. 12;
14 is an exploded perspective view of the components of the fluid injector of FIG. 13;
15 is a cross-sectional view of the inlet portion of the fluid injector of the RDU of FIG. 1 according to another exemplary embodiment;
16 is a cross-sectional view of the integral component of the fluid injector of FIG. 15;
17 is an exploded perspective view of the components of the fluid injector of FIG. 15;

The following description of exemplary embodiment(s) is merely illustrative in nature and is not intended to limit the invention, its application or use.

Exemplary embodiments generally relate to RDUs for non-purge SCR systems where damage is reduced by freezing of the reducing agent, DEF and/or urea solution in the RDU injector.

1 shows an RDU 10 of a non-purge SCR system according to an exemplary embodiment. The RDU 10 includes a solenoid fluid injector, generally designated as 12, which provides a metering function of the fluid and provides preparation for spraying fluid into the vehicle's exhaust gas path when injecting is applied. Accordingly, the fluid injector 12 is constructed and arranged to be associated with an exhaust gas flow path upstream of a selective catalytic reduction (SCR) catalytic converter (not shown). The fluid injector 12 may be an electrically operated solenoid fuel injector. 1 and 2, the fluid injector 12 includes an actuator unit having a coil 14 and a moving armature 16. The components of the injector 12 form a fluid path for the reducing agent, DEF and/or urea solution passing through the injector 12. The reducing agent, DEF, and/or urea solution configured for the RDU 10 to be injected into the vehicle engine's exhaust gas path will hereinafter be referred to as a “reducing agent” for simplicity.

The fluid injector 20 is disposed on the inner carrier 18 of the RDU 10 as shown in FIG. 1. In general, the injector shield indicated by 20 is formed of the upper shield 20A and the lower shield 20B, and the upper shield and the lower shield surround the injector 12, and the carrier 18 and the upper shield ( It is coupled to the carrier 18 by folding the tang of the flange 22 of the lower shield 20B over the shelf feature of 20A). As a result, the shield 20 and the carrier 18 are fixed with respect to the injector 12.

The inlet cup structure of the RDU 10, generally designated 24 in FIG. 1, includes a cup 26 and a fluid supply tube 28 integrally formed with the cup 26. The fluid supply tube 28 is communicatively connected to a source of a reducing agent (not shown), the reducing agent being injected from the fluid outlet 32 of the injector to the exhaust stream of the vehicle engine (not shown) 12 ) To the fluid inlet 30. The fluid outlet 32 of the injector 12 is in fluid communication with the fluid supply tube 28. The fluid outlet 32 is fluidly connected to the flange outlet 34 of the exhaust flange 36 which is directly coupled to the end of the lower shield 20B of the RDU 10.

The injector 12 includes an injector body structure in which components of the injector 12 are disposed. The injector body structure includes a first injector body portion 38 on which the coil 14 and armature 16 are disposed, and a valve body portion 40 on which the valve assembly of the injector 12 is at least partially disposed. The first injector body portion 38 and the valve body portion 40 are fixedly connected to each other directly or indirectly.

1 and 3, the fluid injector 12 includes a tube member 42 disposed at least partially within the first injector body portion 38. The outer surface of the tube member 42 contacts the inner surface of the first injector body portion 38. The open end of the tube member 42 is disposed within the cup 26 and is in fluid communication with the fluid supply tube 28. The O-ring 44 is disposed in the cup 26 close to the open end of the tube member 42 between the inner surface of the cup and the outer surface of the tube member 42. The O-ring 44 serves to ensure that the reducing agent exiting the fluid supply tube 28 passes into the open end of the tube member 42 of the injector 12.

The actuator unit of the fluid injector 12 further includes a pole piece 46 fixedly disposed within the first injector body portion 38. The coil 14 at least partially surrounds the pole piece 46 and the armature 16. The pole piece 46 is arranged upstream of the armature 16 in the injector 12. The pole piece 46 includes a central bore formed through the axial direction.

The armature 16 includes a U-shaped cross section forming a pocket in which at least a portion of the spring 50 is disposed. The spring 50, which is part of the actuator unit, deflects the moving armature 16 such that the armature 16 is spaced from the pole piece 46 when current does not pass through the coil 14. The spring 50 extends partially within the central bore of the pole piece 46. One end of the spring 50 extending in the pole piece 46 contacts the spring adjustment tube 52. The spring adjustment tube 52 is disposed at least partially within the central bore of the pole piece 46 upstream of the spring 50 (with respect to the direction of flow of the reducing agent through the injector 12). The spring adjustment tube 52 includes a bore formed through the axial direction. The through bore of the spring adjustment tube 52 partially forms the fluid path for the reducing agent in the fluid injector 12 and the only fluid path for the reducing agent through the pole piece 46. Due to engagement with the spring 50, a spring adjustment tube 52 is used to calibrate the dynamic flow of reducing agent through the fluid injector 12.

Armature 16 further includes one or more channels 60 (FIGS. 1 and 2) formed through the armature 16 from the interior of the pocket to the upstream end portion of the pin member 58. The channels 60 can be evenly spaced around the armature 16. In one exemplary embodiment, the armature 16 includes a single channel formed all around the base of the pocket formed by the pocket wall 16A. The channel(s) 60 allow the reducing agent to flow from the pocket of the armature 16 into the space around the upstream end of the fin member 58. The pocket and channel(s) 60 of the armature 16 together form part of the reducing agent fluid path of the fluid injector 12, and form the only part of the fluid path that passes through or around the armature 16. .

1, 2 and 5, the valve assembly of the injector 12 includes a sealing member 54 and a seat 56. The sealing member 54 is connected to the armature 16 through a pin member 58 disposed between the downstream end of the armature 16 and the sealing member 54. The sealing member 54, pin member 58 and armature 16 may be combined to form an armature assembly. When the coil 14 is energized, the coil 14 generates an electromagnetic force acting on the armature 16, which overcomes the biasing force from the spring 50 and moves the armature 16 towards the pole piece 46. Correspondingly, the pin member 58 is moved to lift and separate the sealing member 54 from the seat 56, thereby moving the armature assembly to an open position so that the reducing agent passes through the fluid outlet 32 to the flange outlet 34. After passing, it passes through the exhaust gas path of the vehicle engine. When the coil 14 is non-energized, electromagnetic force is dissipated and the spring 50 deflects the armature 16 to move the armature 16 away from the pole piece 46 so that the sealing member 54 seats 56 The armature assembly is again brought into a closed position by engaging with and sealing. When the armature assembly is in the closed position, the reducing agent is prevented from flowing through the seat 56 and the flange exit 34 into the vehicle engine exhaust gas path.

As described above, RDU 10 forms part of a non-purge SCR exhaust aftertreatment system. As a result, a reducing agent remains in the fluid injector 12 after the vehicle engine is turned off. In the exemplary embodiment, fluid injector 12 is configured such that the amount of reducing agent in fluid injector 12 is reduced. In other words, the total volume of the reducing agent present in the fluid path in the fluid injector 12 is reduced. By reducing the space in which the reducing agent is present in the injector 12, the amount of reducing agent in the RDU 10 that can potentially be frozen is reduced, so that the reducing agent freezes and the injector 12 is damaged by the expanding force The risk of this happening is reduced.

In order to reduce the volume of the reducing agent fluid path in the fluid injector 12, the thickness of the valve body portion 40 is increased. In addition, the fin member 58 is configured as a solid element such that the reducing agent does not pass through the fin member but flows around the outer surface of the fin member 58. The gap between the inner surface of the valve body portion 40 and the outer surface of the fin 58 partially forming a fluid path for the reducing agent passing through the injector 12 is narrowed. This narrow portion of the fluid path is the only fluid path where a reducing agent is present between armature 16 and seat 56 in fluid injector 12. The narrow fluid path between the pin 58 and the valve body portion 40 provides a sufficient flow of reducing agent through the fluid injector 12, performing injection of the reducing agent during normal operation of the RDU 10, and at the same time By keeping the volume of the reducing agent in (12) relatively small, it is possible to reduce the risk of damage to the injector 12 when the reducing agent is frozen.

In addition, the thickness of the pocket wall 16A of the armature 16 can be increased by reducing the diameter of the pocket of the armature 16 where the spring 50 is at least partially disposed. In an exemplary embodiment, the thickness of the pocket wall 16A is 45% to 75% of the diameter of the pocket, for example about 60%. Not only does the thickness of the pocket wall 16A increase, but also the thickness of the valve body portion 40 increases, and the fin member 50 is a solid fin, so that the components of the injector 12 are reinforced to reduce the freezing of the reducing agent. You can resist more.

Furthermore, the bore of the spring adjustment tube 52 is sized to reduce the volume of the reducing agent fluid path in the injector 12. In the exemplary embodiment, the diameter of the bore of the spring adjustment tube 52 is 12% to 22% of the outer diameter of the pole piece 46, in particular 16% to 19%.

3 shows the upstream portion of the injector 12. The tube member 42 extends at least partially through the injector 12. The reducing agent fluid path through the injector 12 passes through the tube member 42. The injector 12 includes a filter 204 disposed within the tube member 42 close to the open end of the tube member. The filter 204 is a structurally rigid and sintered metal filter, such as a stainless steel material, to better withstand the expansion forces that occur when the reducing agent freezes. Filter 204 may have a support outer structure for additional strength. As can be best seen in FIG. 3, filter 204 is disposed within cap member 206. The cap member 206 is generally cylindrical in shape with side walls 206A extending in the circumferential direction and defining an interior volume having a size for receiving the filter 204 therein. The cap member 206 is dimensioned to fit within the tube member 42, particularly to allow the outer surface of the side wall 206A of the cap member 206 to contact the inner surface of the tube member 42. The cap member 206 further includes an annular member 206B disposed along the axial end of the cap member 206, and extends radially inward from the side wall 206A. The annular member 206B functions to keep the filter 204 in a fixed position within the cap member 206. The cap member 206 is composed of a metal or similar composition.

The injector 12 further adds a retaining ring 207 disposed within the tube member 42 in contact with the cap member upstream of the cap member 206, as shown in FIGS. Includes. The retainer ring 207 is secured to the tube member 42 along the inner surface of the tube member. The retaining ring 207 fixed in place along the tube member 42 serves to retain the downstream components of the injector 12 in a fixed position within the first injector body portion 38. In an exemplary embodiment, retainer ring 207 is welded along the inner surface of tube member 42. This weld connection is formed along the entire circumference of the upper edge of retainer ring 207. However, it is understood that it is also possible to use other connecting mechanisms to secure the retainer ring 207 to the tube member 42.

1 to 4, the injector 12 further includes a volume reducing member 208 that functions to further reduce the volume of the reducing agent fluid path in the injector 12. The volume reduction member 208 is generally cylindrical in shape, with an upper (upstream) end and a lower (downstream) end, as shown in FIG. 4. In one embodiment, the volume reduction member 208 is made of a metal, such as stainless steel. However, it is understood that the volume reduction member 208 can be formed of other metals or metal compositions. The outer surface of the volume reduction member 208 is sized to contact the inner surface of the tube member 42.

The volume reduction member 208 further adds an axially formed bore 208A (FIGS. 2 and 3) through the volume reduction member 208 from one axial (top) end to the other axial (bottom) end. Includes. The bore 208A is positioned along the longitudinal axis of the volume reduction member 208, and the bore itself forms part of the fluid path through the injector 12. The bore 208A forms a unique fluid path for the reducing agent to pass through or around the volume reduction member 208. In an exemplary embodiment, the diameter of the bore 208A is 12% to 20% of the outer diameter of the volume reducing member 208, for example about 16%. Since the volume reduction member 208 extends radially to the inner surface of the tube member 42, and the diameter of the bore 208A is smaller than the outer diameter of the volume reduction member 208, the volume reduction member 208 is The reducing agent may reduce the volume or volume of the space in which the reducing agent may be present, thereby reducing the volume of the fluid path in which the reducing agent is present. The volume reduction member 208 prevents the pin adjustment tube 52 from retaining the spring adjustment tube 52 in place within the injector 12 to maintain the desired force on the spring 50 to prevent loss of calibration. Help more. Specifically, the retainer ring 207 maintains the position of the filter 204 and the corresponding cap member 206, which maintains the position of the volume reducing member 208, which maintains the position of the spring adjustment member 52.

1 to 4, the fluid injector 12 further includes a volume compensating member 210 disposed between the lower end (downstream) end of the volume reducing member 208 and the upper end of the pole piece 46. The volume compensating member 210 is made of an elastic material, and has a function of occupying a space between the volume reducing member 208 and the pole piece 46 to further reduce the volume of the fluid path in which the reducing agent is present in the injector 12. do. The volume compensating member 210 can remain compressed within the injector 12 when assembled, the volume reducing member 208, the pole piece 46, the inner surface of the tube member 42, and the spring adjustment member 52 ).

5 shows the downstream end portion of the fluid injector 12. As can be seen, sheet 56 includes a bore formed axially through sheet 56. In the exemplary embodiment, by reducing the length of the through bore of the seat 56, the volume of the fluid path through which the reducing agent passes through the seat 56 is present, and in particular of the seat 56 engaging the sealing member 54. The sac volume under the sealing band can be further reduced.

According to one exemplary embodiment, the fluid injector 12 includes a plurality of orifice disks 212 arranged in a stacked arrangement. The orifice disk stack is disposed at the downstream end of the seat 56. In the exemplary embodiment shown in FIG. 5, the disk stack includes a first disk 212A having one or more orifices configured to provide a desired spray pattern of a reducing agent exiting the injector. It is understood that the dimension and position of the orifice of the first disk 212A may vary and may vary depending on the reducing agent injection requirements of a particular vehicle engine. The disc stack further includes a second disc 212B disposed downstream of the first disc 212A and having an orifice through which a reducing agent spray passes. The second disk 212B is thicker than the thickness of the first disk 212A and disposed in contact with the first disk 212A, and is further due to the expansion force generated by freezing of the reducing agent upstream of the first disk 212A. The first disk 212A is supported to prevent the thin first disk 212A from being deformed.

As described above, the fluid injector 12, and particularly its components, are configured to reduce the volume of the fluid path in which a reducing agent is present in the injector 12. In an exemplary embodiment, components of the injector 12 (coil 14, armature 16, pole piece 46, spring adjustment tube 52, volume reduction member 208, volume compensation member 210, Filter 204, retaining ring 207, spring 50, pin member 58, sealing member 54, seat 56, first injector body portion 20A and valve body portion 40 The ratio of the volume of the fluid path in the fluid injector 12 to the volume of the fluid, including but not limited to) is 0.08 to 0.30, in particular 0.12 to 0.20, for example about 0.15. This volume is the first plane along the open end of the tube member 42 (ie, the fluid inlet 30) and the agent along the bottom (downstream) surface of the second disc 212B (ie, fluid outlet 32). From the two planes, it is calculated between the orthogonal planes with respect to the longitudinal axis of the fluid injector 12. It is understood that the specific ratio of the volume of the reducing agent path to the volume of the injector components in the fluid injector 12 can vary depending on the number of cost and performance related factors, and can be any value from about 0.08 to about 0.30. Reducing the ratio of the reducing agent fluid path volume to the volume of the injector component in the fluid injector within the above range advantageously results in fewer reducing agents present in the injector 12, even when the reducing agent in the injector 12 freezes The risk of damaging the RDU 10 can be reduced.

In another exemplary embodiment shown in FIGS. 6-8, the fluid injector 12 includes a volume reduction member 308 having many of the characteristics of the volume reduction member 208 described above with respect to FIGS. 1-5. do. Similar to the volume reduction member 208, the volume reduction member 308 is composed of stainless steel or a similar composition, and is disposed within the tube member 42 of the fluid injector 12 between the volume compensation member 210 and the filter 204 do. However, the volume reduction member 308 includes a first portion 308A and a second portion 308B. As shown in Fig. 7, each of the first portion 308A and the second portion 308B has a cylindrical shape, and the outer diameter of the first portion 308A is smaller than the outer diameter of the second portion 308B. . The outer diameter of the first portion 308A is smaller than the diameter of the second portion 308B by the thickness of the side wall 306A of the cap member 306, as described in more detail below. The volume reduction member 308 includes top (upstream) and bottom (downstream) end portions forming axial ends of the first portion 308A and the second portion 308B, respectively. The outer surface of the second portion 308B is sized to contact the inner surface of the tube member 42.

As described above, the outer diameter of the first portion 308A of the volume reducing member 308 is smaller than the outer diameter of the second portion 308B of the volume reducing member. 6 to 8, the volume reduction member 308 extends axially between the outer surface of the first portion 308A and the outer surface of the second portion 308B, and a physical interface therebetween. It includes an angled annular surface or skirt 308D that acts as. The angle of the angled surface 308D relative to the longitudinal axis of the volume reducing member 308 and/or the injector 12 is an acute angle. Alternatively, the angle of the angled surface 308D is perpendicular to the longitudinal axis of the volume reducing member 308 and/or the injector 12.

The volume reduction member 308 further includes a bore 308C formed axially through the volume reduction member 308 from one axial (top) end to the other axial (bottom) end. The bore 308C is positioned along the longitudinal axis of the volume reducing member 308 and the bore itself forms part of the reducing agent fluid path through the reducing agent through the injector 12 and passes through the volume reducing member 308 or It forms the only reducing agent fluid path that passes around. In the exemplary embodiment, the diameter of the bore 308C is 12% to 20% of the outer diameter of the volume reduction member 308, for example about 16%. Since the volume reduction member 308 extends to the inner surface of the tube member 42 and the diameter of the bore 308C is relatively small compared to the outer diameter of the volume reduction member 308, the volume reduction member 308 is a sprayer ( 12) By occupying my volume, the space or volume of the reducing agent fluid path through the injector 12 is reduced, reducing the amount of reducing agent that can damage the injector 12 when frozen in the injector 12.

The cap member 306 includes many of the same properties of the cap member 206 described above with respect to FIGS. 1-5. As shown in FIG. 7, the cap member 306 is generally cylindrical in shape with side walls 306A extending in the circumferential direction and defining an interior volume having a size to accommodate the filter 204 therein. The cap member 306 is sized to fit within the tube member 42, particularly dimensioned such that the outer surface of the side wall 306A of the cap member 306 contacts the inner surface of the tube member 42. The cap member 306 further includes an annular member 306B disposed along the axial (upstream) end of the cap member 306 and extending radially inward from the side wall 306A. The annular member 306B functions to hold the filter 204 in the cap member 306 in a fixed position. Like the cap member 206, the cap member 306 is composed of a metal or similar composition, and provides a structural support to the filter 204.

In the exemplary embodiment, the cap member 306 is engaged with the volume reduction member 308 and secured. In this way, filter 204, cap member 306, and volume reduction member 308 form a single, unitary, integral component as shown in FIG. Having a single integral component formed from the filter 204, cap member 306 and volume reduction member 308, advantageously allows a simpler and less complex process to assemble the injector 12 during manufacture. have.

In an exemplary embodiment, the cap member 306 is fitted, engaged, or otherwise in at least a portion of the first portion 308A of the volume reducing member 308, as shown in FIGS. 6 and 8 Is attached. In one exemplary embodiment, the cap member 306 engages with the first portion 308A by press fit. In another exemplary embodiment, the cap member 306 includes a first portion (such as a fillet weld) between the bottom surface 306C of the cap member 306 and the radial outer surface of the first portion 308A. 308A). In each of these embodiments, the angled surface 308D provides sufficient spacing to secure the cap member 306 to the first portion 308A. It is understood that the cap member 306 can be secured to the first portion 308A of the volume reduction member 308 through another mechanism.

By fitting the cap member 306 over the first portion 308A of the volume reduction member 308, the outer diameter of the side wall 306A is the same or almost the same as the outer diameter of the second portion 308A. See Figures 6 and 8.

As described above, the volume reduction member 308 is made of a metal, such as stainless steel, according to an exemplary embodiment. In another exemplary embodiment, part of the second portion 308B is made of plastic or a similar composition. Specifically, as shown in FIGS. 9 to 11, the first part 308B-1 of the first part 308A and the second part 308B is formed as a single metal member, and the second The second part 308B-2 of the part 308B is plastic overmolded around the first part. 11 shows a first part 308B-1 of the metal first part 308A and the second part 308B. The first part 308B-1 of the second part 308B, as shown in FIG. 10, is an intermediate section 308B-3 extending in a direction away from the first part 308A in the axial (downstream) direction. ), and a distal section 308B-4 attached to this intermediate section 308B-3 and extending axially (downstream). The distal section 308B-4 is radial from the longitudinal axis of the volume reduction member 308 (and/or the injector 12) rather than the radial extension of the intermediate section 308B-3 to form a ledge. It extends in the direction away. The second part 308B-2 of the second part 308B made of overmolded plastic or other similar composition is formed around the protrusion formed by the intermediate section 308B-3 and the distal section 308B-4 to reduce the volume It is intended to form the member 308 as a single unitary integrated component. As described above, the volume reduction member 308 is connected to the cap member 306 to form a single assembly component for use when assembling the injector 12, the volume reduction member 308, filter 204 ) And cap member 306.

During assembly of the injector 12, a single assembly component (filter 204, cap member 306 and volume reduction member 308) is inserted into the tube member 42 under pressure while in contact with the volume compensator 212. do. After insertion and while still under pressure, the cap member 306 is welded to the tube member 42 along all intersections along the top portion of the tube member 42. In one embodiment, the weld connection is fillet welding.

12 shows a fluid injector 12 according to another exemplary embodiment. In this embodiment, the fluid injector 12 includes a filter 204 as described above, and a cap member 306 on which the filter 204 is disposed. The fluid injector 12 also includes a calibration filter tube 402 and a volume reduction member 408. The calibration filter tube 402 includes a bore 402A formed through the calibration filter tube 402 axially. At one (upstream) end of the calibration filter tube 402, the bore 402A is in fluid communication with the filter 204 to receive a reducing agent from the filter. At the other (downstream) end of the calibration filter tube 402, the bore 402A provides a reducing agent to the armature 16. In this way, the calibration filter tube 402 forms part of the fluid path for the reducing agent passing through the fluid injector 12 and forms a unique fluid path from the filter 204 to the armature 16. If the diameter of the bore 402A of the calibration filter tube 402 is smaller than the inner diameter of the tube member 42, the volume of the fluid path for the reducing agent passing through the injector 12 is reduced, so that the reducing agent freezes inside. If possible, it can reduce the adverse effects that can occur.

12-14, the calibration filter tube 402 further includes a first end portion 402B disposed at least partially within the cap member 306 and in contact with the filter 204. The first end 402B is generally disc shaped with side walls 402C in contact with the inner surface of the side walls 306A of the cap member 306. In one exemplary embodiment, the first end portion 402B of the calibration fluid member 402 comprises a cap member 306, a filter 204, and a calibration filter tube 402 with a single, integrally integrated sub-assembly component. It is attached to the cap member 306 to form, allowing the fluid injector 12 to be simply assembled. In one exemplary embodiment, the cap member 306 engages the first end portion 402B, and in particular engages the first end portion to form an engagement. In another exemplary embodiment, the cap member 306 is made of a fillet weld connection between the axial end of the side wall 306A of the cap member 306 and the outer surface of the side wall 402C of the first portion 402A. It is welded to one end portion 402B. Alternatively or additionally, it is understood that the cap member 306 can be secured to the first end portion 402B of the calibration filter tube 402 using other techniques.

The calibration filter tube 402 further includes an elongated second portion 402D extending axially from the first portion 402A as shown in FIGS. 12-14. The second portion 402D has a size that extends into the pole piece 46 such that the second end 402E opposite the first end portion 402B engages the spring 50 (FIG. 12). The second portion 402D is generally cylindrical in shape with a bore 402A disposed therein. The calibration filter tube 402 further includes an annular tab 402F extending radially outward from the outer surface of the second portion 402D. The tab 402F extends slightly outwardly from the outer surface of the second portion 402D of the calibration filter tube 402 and is positioned along the second portion to contact the inner surface of the pole piece 46 forming the central bore. . This contact between the center bore of the pole piece 46 and the tab 402F causes the calibration filter tube 402 to form an attachment with the pole piece 46 by press fit.

As described above, the second end 402E of the calibration filter tube 402 contacts and engages the spring 50. Due to the engagement between the calibration filter tube 402 and the spring 50 and the engagement between the armature 16 and the spring 50, the calibration filter tube 402 calibrates the dynamic flow of the reducing agent through the fluid injector 12. Used to Specifically, if the cap member 306, filter 204 and calibration filter tube 402 are formed as a single, integral, integrated sub-assembly component, the spring 50 before welding the cap member 306 to the tube member It is simplified to place the calibration filter tube 402 in the desired position within the tube member 42 to provide the desired calibrated force to the tube.

The calibration filter tube 402 is formed of a metal composition, such as stainless steel.

With continued reference to FIGS. 12-14, the injector 12 further includes a volume reduction member 408 disposed around the second portion 402D of the calibration filter tube 402. The volume reduction member 408 has a cylindrical shape with a central bore formed through the volume reduction member 408 axially. The center bore of the volume reduction member 408 is sized to accommodate the calibration filter tube 402 therein. 12, the outer radial surface of the volume reduction member 408 contacts the inner surface of the tube member 42. One axial (upstream) end of the volume reduction member 408 is disposed adjacent to and contacts the first end portion 402B of the calibration filter tube 42, and the other axial (downstream) of the volume reduction member 408 ) The end is disposed adjacent to the upstream end of the pole piece 46 and contacts. In this way, the volume reduction member 408 is made up of the tube member 42 and the calibration filter tube 402 upstream of the pole piece 46 and downstream of the first end portion 402B of the calibration filter tube 402. Occupy the space between the two parts 402D. In one exemplary embodiment, the volume reduction member 408 allows the volume reduction member 408 to form a single, integrally integrated component with the cap member 306, filter 204, and calibration filter tube 402. It is attached to the calibration filter tube 402.

In one exemplary embodiment, the volume reduction member 408 is composed of an elastic and compressible material, and is compressible at least axially along the fluid injector 12. The axially compressible volume reduction member 408 is a single assembly component (cap member 306, filter 204 and calibration filter) so that the opening and closing force of the valve assembly of the fluid injector 12 can be easily calibrated as desired. The tube 402 allows positioning within the tube member 42 relative to the pole piece 46. In one embodiment, the volume reduction member 408 consists of a closed cell foam. However, it is understood that the volume reduction member 408 can be constructed from other compressible materials. When composed of a closed cell foam, the volume reduction member 408 is compressible in the axial (longitudinal) and radial (lateral) directions. In one exemplary embodiment, the volume reduction member 408 is compressed in the fluid injector 12.

15-17 show a fluid injector 12 according to another exemplary embodiment. In this embodiment, the fluid injector 12 includes a filter 204 as described above, and a cap member 306 on which the filter 204 is disposed. In addition, the fluid injector 12 includes a calibration filter tube 502. The calibration filter tube 502 has many features of the calibration filter tube 402 described above with respect to FIGS. 12-14.

The calibration filter tube 502 includes a bore 502A formed through the calibration filter tube 502 axially. At one (upstream) end of the calibration filter tube 502, the bore 502A is in fluid communication with the filter 204 to receive a reducing agent from the filter. At the other (downstream) end of the calibration filter tube 502, the bore 502A provides a reducing agent to the armature 16. In this way, the calibration filter tube 502 forms part of the fluid path for the reducing agent passing through the fluid injector 12 and forms a unique fluid path from the filter 204 to the armature 16. If the diameter of the bore 502A of the calibration filter tube 502 is smaller than the inner diameter of the tube member 42, if the reducing agent freezes by reducing the volume of the fluid path for the reducing agent passing through the injector 12 It can reduce the possible adverse effects.

15-17, the calibration filter tube 502 further includes a first end portion 502B disposed at least partially within the cap member 306 to contact the filter 204. The first end portion 502B is generally disc shaped with side walls 502C in contact with the inner surface of the side walls 306A of the cap member 306. In one exemplary embodiment, the first end portion 502B of the orthodontic fluid member 502 comprises a cap member 306, a filter 204, and a orthodontic filter tube 502 in a single, integrally integrated sub-assembly component. It is attached to the cap member 306 to form, allowing the fluid injector 12 to be simply assembled. In one exemplary embodiment, the cap member 306 engages with the first end portion 502B, and in particular engages with the first end portion to form an engagement. In another exemplary embodiment, the cap member 306 is such as a fillet weld connection between the axial end of the side wall 306A of the cap member 306 and the outer surface of the side wall 502C of the first portion 502B. It is welded to the first end portion 502B. Additionally or alternatively, it is understood that the cap member 306 can be secured to the first end portion 502B of the calibration filter tube 502 using other techniques.

The calibration filter tube 502 is elongated second portion 502D extending axially from the first portion 502A, and axially from the second portion 502D as shown in FIGS. 15 to 17. It further includes an elongated third portion 502E. The third portion 502E is sized to extend into the pole piece 46 such that the second end 502F of the calibration filter tube 502 opposite the first end portion 502B engages the spring 50 (FIG. 12). Have The second portion 502D and the third portion 502E are generally cylindrical in shape with the bore 502A disposed therein.

In one exemplary embodiment, the outer diameter of the second portion 502D is greater than the outer diameter of the third portion 502E. The outer diameter of the third portion 502E is sized to be received within the central bore of the pole piece 46.

The calibration filter tube 502 further includes an annular tab 502G (FIG. 17) extending radially outward from the outer surface of the third portion 502E. The tab 502G extends slightly outwardly from the outer surface of the third portion 502E of the orthodontic filter tube 502 to contact the inner surface of the pole piece 46 forming the central bore and is axial along this third portion Is located as This contact between the center bore of the pole piece 46 and the tab 502G causes the calibration filter tube 502 to form an engagement with the pole piece 46 by press fit.

The calibration filter tube 502 is formed of a metal composition, such as stainless steel.

As described above, the second end 502F of the calibration filter tube 502 contacts and engages the spring 50. Due to the engagement between the calibration filter tube 502 and the spring 50 and the engagement between the spring 50 and the armature 16, the calibration filter tube 502 generates a dynamic flow of reducing agent through the fluid injector 12. Used for calibration. Specifically, if the cap member 306, filter 204 and calibration filter tube 502 are formed as a single, integral, integrated sub-assembly component, the fluid injector 12 before welding the cap member 306 to the tube member ) It is simplified to position the calibration filter tube 502 in the desired position in the tube member 42 to provide the desired calibrated force to the spring 50 that sets the opening and closing force against the valve assembly.

With continued reference to FIGS. 15-17, the injector 12 further includes a volume reduction member 508 disposed around the second portion 502D of the calibration filter tube 502. The volume reduction member 508 has a generally cylindrical shape with a central bore formed axially through the volume reduction member 508. The central bore of the volume reduction member 508 is sized to receive the second portion 502D of the calibration filter tube 502 therein. 12, the outer radial surface of the volume reduction member 508 contacts the inner surface of the tube member 42. One axial (upstream) end of the volume reduction member 508 is disposed adjacent to and in contact with the first end portion 502B of the calibration filter tube 42, and the other axial direction (downstream) of the volume reduction member 508 ) The end is disposed adjacent to the upstream end of the pole piece 46 and contacts. In this way, the volume reduction member 508 is made up of the tube member 42 and the calibration filter tube 502 upstream of the pole piece 46 and downstream of the first end portion 502B of the calibration filter tube 502. Occupy the space between the two parts 502D.

In one exemplary embodiment, the volume reduction member 508 is composed of a compressible material, such as at least axially compressible along the fluid injector 12. The at least axially compressible volume reduction member 508 is a single assembly component (cap member 306, filter 204, and calibration filter tube 502) so that the valve assembly of the fluid injector 12 can be calibrated as desired. ) To enable positioning within the tube member 42 relative to the pole piece 46. In one exemplary embodiment, the volume reduction member 508 is compressed in the fluid injector 12.

15-17, the volume reduction member 508 includes sidewalls 508A extending between two axial ends. The axial end wall 508B downstream of the volume reduction member 508 extends radially inward from the sidewall 508A to contact the outer surface of the third portion 502E of the calibration filter tube 502. The axial end upstream of the volume reduction member 508 can be open and contact the downstream surface of the first portion 502B of the calibration filter tube 502.

The sidewalls 508A of the volume reduction member 508 are peaks and valleys of the sidewalls in a wave-like pattern with respect to the longitudinal axis of the volume reduction member 508 and/or the injector 12 as shown in FIGS. 15 to 17. The alternating axial forms a waveform. Having a corrugated sidewall 508A allows the sidewall 508A to be compressible in the axial (longitudinal) and radial (lateral) directions or partially folded in other ways. In one exemplary embodiment, the volume reducing member 508 is composed of a compressible elastic material, such as a rubber composition or other similar material. The volume reduction member 508 can be in a compressed state within the fluid injector 12.

Exemplary embodiments have been described herein in an exemplary manner, but it should be understood that the terminology used is not intended to limit the invention but to have the nature of describing the invention. Obviously, many modifications and variations of the invention will be possible in light of the above description. Since the above description is merely illustrative in nature, modifications may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (20)

As a reducing agent delivery unit,
A fluid injector having a fluid inlet disposed at a first end of a fluid injector to receive a reducing agent, and a fluid outlet disposed at a second end of the fluid injector to discharge the reducing agent, wherein the fluid injector comprises the fluid Forming a fluid path for the reducing agent from an inlet to the fluid outlet, the fluid injector,
A tube member having an end disposed on the fluid inlet side of the fluid injector and configured to pass a reducing agent along the fluid path;
A filter disposed within the tube member;
A calibration filter tube disposed within the tube member downstream of the filter with respect to the flow direction of the reducing agent along the fluid path from the fluid inlet to the fluid outlet of the fluid injector, the calibration filter tube comprising a first end portion and A calibration filter tube having a second end, further comprising a bore formed axially through the calibration filter tube, the bore forming at least a portion of the fluid path through the fluid injector;
An actuator unit disposed downstream of the calibration filter tube in the fluid injector and engaging the second end of the calibration filter tube;
A valve assembly operatively coupled to the actuator unit, the position of the calibration filter tube in the tube member at least partially establishing an opening force against the valve assembly; And
A volume reducing member having a bore through which the orthodontic filter tube extends and occupying a space between the outer surface of the orthodontic filter tube and the inner surface of the tubular member;
The filter, the calibration filter tube and the volume reduction member form a single sub-assembly component of the fluid injector,
The actuator unit includes a pole piece disposed at a fixed position in the fluid injector and having a bore formed through the axial direction,
The calibration filter tube includes a second part extending axially from the first end part of the calibration filter tube, and a third part disposed between the second end and the second part of the calibration filter tube. However, the volume reduction member is disposed around the second portion, the third portion is disposed within the bore of the pole piece, and the downstream end of the volume reduction member is the flow direction of the reducing agent along the fluid path. A reducing agent delivery unit, disposed towards the upstream end of the pole piece. The reducing agent delivery unit according to claim 1, wherein the volume reducing member is formed of a compressible material. 3. The reducing agent delivery unit of claim 2, wherein the compressible material comprises one of a rubber composition and a closed cell foam. 3. The reducing agent delivery unit of claim 2, wherein the volume reduction member comprises a sidewall, wherein the sidewall of the volume reduction member forms a waveform in a direction along the longitudinal axis of the fluid injector. The fluid injector of claim 1, further comprising a cap member having a side wall forming an inner space in which the filter is disposed, the side wall contacting the first end portion of the calibration filter tube, reducing agent delivery. unit. The reducing agent delivery unit according to claim 5, wherein the first end portion of the calibration filter tube is disposed in the inner space of the cap member. 6. The cap member of claim 5, wherein the first end portion of the calibration filter tube is configured such that the calibration filter tube, the cap member, the volume reduction member, and the filter form a single sub-assembly component of the fluid injector. A reducing agent delivery unit attached to the side wall. The armature according to claim 1, wherein the actuator unit is movably positioned in the fluid injector and has a pocket, a coil disposed around the pole piece and the armature, and at least partially disposed in the pocket of the armature. Further comprising a spring, wherein the calibration filter tube is disposed in the bore of the pole piece such that the second end of the calibration filter tube contacts the spring, the spring armature when there is no current passing through the coil. Reducing agent delivery unit to deflect the valve assembly away from the pole piece, placing the valve assembly in a closed position to prevent the reducing agent from passing through the fluid outlet. delete The reducing agent delivery unit of claim 1, wherein the outer diameter of the second portion of the calibration filter tube is larger than the outer diameter of the third portion of the calibration filter tube. As a fluid injector,
A fluid inlet disposed at a first end and configured to receive fluid, and a fluid outlet disposed at a second end of the fluid injector to discharge the fluid, the fluid injector directing the fluid from the fluid inlet to the fluid outlet. A fluid inlet and a fluid outlet forming a fluid path for the;
A tube member having an end disposed on the fluid inlet side of the fluid injector and configured to pass fluid along the fluid path;
A filter disposed within the tube member;
A calibration filter tube disposed within the tube member downstream of the filter with respect to a direction of flow of fluid along the fluid path from the fluid inlet of the fluid injector to the fluid outlet, the calibration filter tube comprising a first end portion and A calibration filter tube having a second end, further comprising a bore formed axially through the calibration filter tube, the bore forming at least a portion of the fluid path through the fluid injector;
An actuator unit disposed downstream of the calibration filter tube in the fluid injector and engaging the second end of the calibration filter tube;
A valve assembly operatively coupled to the actuator unit, the position of the orthodontic filter tube in the tube member establishing an opening force against the valve assembly; And
A cap member having a side wall defining an inner space in which the filter is disposed, the side wall being such that the cap member, the filter and the calibration filter tube form a single sub-assembly component of the fluid injector Is attached in contact with the first end portion of,
The calibration filter tube further comprises a volume reducing member having a bore extending,
The actuator unit includes a pole piece disposed at a fixed position in the fluid injector and including a bore formed through the axial direction,
The calibration filter tube includes a second part extending axially from the first end part of the calibration filter tube, and a third part disposed between the second end and the second part of the calibration filter tube. , The volume reduction member is disposed around the second portion, the third portion is disposed in the bore of the pole piece, and the downstream end of the volume reduction member is the pole with respect to the flow direction of the fluid along the fluid path. A fluid injector disposed towards the upstream end of the convenience. 12. The method of claim 11, wherein the volume reduction member occupies a space between the outer surface of the calibration filter tube and the inner surface of the tube member, and the volume reduction member, the cap member, the filter and the calibration filter tube are the A fluid injector forming a single sub-assembly component of the fluid injector. The fluid injector of claim 12, wherein the volume reduction member is compressible. The fluid injector of claim 13, wherein the volume reduction member is comprised of one of a rubber composition and a closed cell foam. The fluid injector of claim 12, wherein the volume reduction member comprises a sidewall, wherein the sidewall of the volume reduction member forms a waveform along the longitudinal axis of the fluid injector. 13. The armature according to claim 12, wherein the actuator unit is movably positioned in the fluid injector and includes a pocket, a coil disposed around the pole piece and the armature, and at least partially disposed in the pocket of the armature. Further comprising a spring, wherein the calibration filter tube is disposed in the bore of the pole piece such that the second end of the calibration filter tube contacts the spring, the spring armature when there is no current passing through the coil. Deflecting away from the pole piece, placing the valve assembly in a closed position to prevent fluid from passing through the fluid outlet. delete The fluid injector of claim 11, wherein an outer diameter of the second portion of the calibration filter tube is larger than an outer diameter of the third portion of the calibration filter tube. 12. The method of claim 11, wherein the orthodontic filter tube further comprises an annular tab extending from the third portion of the orthodontic filter tube, the annular tab being disposed within the bore of the pole piece to engage with the pole piece by press fit To form a fluid injector. 12. The fluid injector of claim 11, wherein the first end portion of the calibration filter tube is disposed in the interior space of the cap member.

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