Abstract
Vapors in the fuel tank of a vehicle are collected in a carbon canister. An ejector or aspirator is used to purge the carbon canister in a pressure-charged engine in which a positive pressure exists in the intake. A compact ejector includes a substantially planar flange and a venturi tube coupled to the flange with a central axis of the venturi tube substantially parallel to the flange. By manufacturing the ejector in two pieces, dimensions within the ejector: throat, converging section, and diverging section, is more accurate than prior art manufacturing techniques thereby providing better flow characteristics throughout the boost range. By forming one of the two pieces of the ejector integrally with the air intake component in which it is coupled, decreases part count and the number of manufacturing processes.
Claims
1. An ejector system for a boosted internal combustion engine, comprising: a first section of an intake air component having a first ejector portion unitarily formed; and a second ejector portion affixed to the first ejector portion wherein: the first and second ejector portions comprise a venturi tube having a converging section, a throat, and a diverging section; the ejector further comprises a first tube and a second tube; and the second tube fluidly couples to the venturi tube proximate the throat.
2. The ejector system of claim 2, further comprising: a second section of the intake air component affixed to the first section of the intake air component.
3. The ejector system of claim 1 wherein the first and second ejector portions each comprise about one-half of the venturi tube.
4. The ejector system of claim 1 wherein: the first and second tubes are integrally formed with the first ejector portion; and the second tube fluidly couples with an upstream end of the converging section.
5. The ejector system of claim 1 wherein the intake air component an air filter box.
6. The ejector system of claim 1 wherein the intake air component is an intake air duct.
7. The ejector system of claim 1 wherein the center of the venturi tube is substantially parallel to a wall of the intake air component to which it is coupled.
8. An ejector system for a boosted internal combustion engine, comprising: a first section of an intake air component comprising a first ejector portion unitarily formed therewith; a second section of the intake air component affixed to the first section of the intake air component; and a second ejector portion affixed to the first ejector portion wherein: the first and second ejector portions comprise a venturi tube having a diverging section, a throat section, and a converging section; the first and second ejector portions each comprise portions of the diverging, throat, and converging sections.
9. The ejector system of claim 8 wherein the second section of the intake air component is affixed after the second ejector portion is affixed to the first ejector portion.
10. The ejector system of claim 8 wherein first and second intake air components are affixed by one of: sonic welding, vibration welding, induction welding, laser welding, snap fitting, ultrasonic welding, a hot plate, and infrared welding, and thermal welding.
11. The ejector system of claim 8, further comprising: a first tube fluidly coupled to the converging section of the venturi tube; and a second tube fluidly coupled proximate the throat section of the venturi tube wherein the first and second tubes are integrally formed with the first section of the air intake component.
12. The ejector system of claim 8 wherein: the air intake component is an intake air duct; and the first section of the intake air duct and the second section of the intake air duct couple axially.
13. The ejector system of claim 8, wherein first and second ejector portions are affixed by one of: sonic welding, vibration welding, induction welding, laser welding, snap fitting, ultrasonic welding, a hot plate, and infrared welding, and thermal welding.
14. The ejector system of claim 11, wherein a centerline of the first tube forms an acute angle with a surface of the air intake component proximate the first tube.
15. A method to fabricate an air intake component with an ejector, comprising: injection molding a first portion of the air intake component, the air intake component comprising a first venturi tube portion; injection molding a second venturi tube portion; and affixing the first venturi tube portion to the second venturi tube portion.
16. The method of claim 15 wherein: the first and second venturi tube portions are part of the ejector; from upstream to downstream, the venturi tube comprises a converging section, a throat section, and a diverging section; the ejector further comprises first and second tubes that are integrally formed with the first venturi tube portion; the first tube fluidly couples to an upstream end of the converging section; and the second tube fluidly couples proximate the throat section.
17. The method of claim 15 wherein: the first and second venturi tube portions are part of the ejector; from upstream to downstream, the venturi tube comprises a converging section, a throat section, and a diverging section; the ejector further comprises first and second tubes that are integrally formed with the second venturi tube portion; the first tube fluidly couples to an upstream end of the converging section; and the second tube fluidly couples proximate the throat section.
18. The method of claim 15, further comprising: injection molding a second portion of the air intake component; and affixing the second portion of the air intake component to the first portion of the air intake component wherein the affixing of the second portion of the air intake component to the first portion of the air intake component occurs after the first venturi tube portion is affixed to the second venturi tube portion.
19. The method of claim 15 wherein the affixment of the first venturi tube portion to the second venturi tube portion is by one of: sonic welding, vibration welding, induction welding, laser welding, ultrasonic welding, hot plate, and infrared welding, thermal welding, and snap fitting.
20. The method of claim 15 wherein the air intake component is one of an intake air component and an air filter box.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] FIG. 1 is an illustration of a canister purge system which includes an ejector according to the prior art;
[0039] FIG. 2 is a prior art ejector;
[0040] FIG. 3 is the ejector of FIG. 2 in cross section;
[0041] FIG. 4 is the ejector of FIG. 2 shown installed in an air box;
[0042] FIG. 5 is an illustration of an ejector prior to assembly in an intake air duct;
[0043] FIG. 6 is a cross-sectional illustration of the two-piece ejector of FIG. 5;
[0044] FIGS. 7-9 are illustrations of a first embodiment of a portion of an air intake duct with a portion of an ejector unitarily molded with the intake duct;
[0045] FIGS. 10-12 are illustrations of a second embodiment of a portion of an air intake duct with a portion of an ejector unitarily molded with the intake duct;
[0046] FIGS. 13-15 are illustrations of a third embodiment of a portion of an air intake duct with a portion of an ejector unitarily molded with the intake duct;
[0047] FIGS. 16-18 are illustrations of an air filter box with a portion of an ejector unitarily molded with the air filter box;
[0048] FIGS. 19 and 20 show snap-fit connections for coupling first and second ejector portions;
[0049] FIGS. 21 and 22 are flowcharts indicating processes by which the air intake component and an ejector are fabricated;
[0050] FIG. 23 is an embodiment of an air intake duct with an ejector unitarily molded with the intake duct; and
[0051] FIG. 24 is a graph showing a comparison of flow characteristics of a prior art ejector, a disclosed ejector, and the standard to be met.
DETAILED DESCRIPTION
[0052] As those of ordinary skill in the art will understand, various features of the embodiments illustrated and described with reference to any one of the Figures may be combined with features illustrated in one or more other Figures to produce alternative embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations. Those of ordinary skill in the art may recognize similar applications or implementations whether or not explicitly described or illustrated.
[0053] An ejector 150 disclosed in commonly assigned application U.S. Ser. No. 15/225,920 is shown prior to installation in an air duct 170. Ejector 150 is shown in cross section in FIG. 6. Ejector 150 has a first tube 152 that can be coupled to an intake duct (not shown) to bring in fresh air and a second tube 154 that can be coupled to a carbon canister (not shown) in which fuel vapors are stored. Tubes 152 and 154 extend out from a flange 156. A venturi tube 160 of ejector 150 has a converging section 162, a throat (not shown) and a diverging section 164 that has an exit 166. Ejector 150 is made up of two portions, an upper portion that includes tubes 152 and 154, flange 156, and an upper portion of venturi tube 160; and a lower portion that includes a lower portion of venturi tube 160. Ejector 150 is shown above an air duct 170 prior to assembly. Air duct 170 has a protuberance 178 that accommodates forming a flat surface 176 (flange) onto which flange 156 of ejector 150 mounts and couples. Surface 176 surrounds an opening 174 into which venturi tube 160 is placed. Opening 174 is large enough to allow venturi tube 160 to go into opening 174 straight on, as shown by arrows 180. Ejector 150 is affixed to air duct 170 by friction welding or any other suitable process.
[0054] Ejector 150 of FIG. 5 is shown in cross section in FIG. 6. Venturi tube 160 includes converging section 162, a throat 163, and diverging section 164 that has an exit 166. Ejector 150 is made of two pieces that are coupled together via friction welding or any suitable technique. The first piece includes tubes 152 and 154, flange 156, and the upper half of venturi tube 160, i.e., above lines 181 and 182. The second piece of ejector 150 includes the portion of venturi tube 160 below lines 181 and 182.
[0055] In FIG. 7, a portion of an air duct 200 is made up of two portions 202 and 204 that couples along axial connections. Duct 200 has a circular inlet 206. An ejector is integrated into air duct 200, with tubes 212 and 214 extending outwardly from a surface of duct 200. A cross section of air duct 200 is shown in FIG. 8. Ejector 210 is shown with tubes 212 and 214 extending out of a first portion 202 of the air intake duct. Tube 212, tube 214, and the portion of a venturi tube 216 that is above lines 220 and 222 (centerlines through venturi tube 216) are formed integrally with first portion. 202. A portion of venturi tube 216 that is below lines 220 and 222 is formed separately and then attached afterward. Another view of ejector 210 and first portion 202 is shown. Venturi tube 216 has an upper portion 224, that along with tubes 212 and 214 are integrally formed with first portion 202. A lower portion 226 of venturi tube 216 is formed separately. In FIG. 9, lower portion 226 of the venturi tube of ejector 210 is shown affixed to upper portion 224 of the venturi tube. Lower portion 226 is coupled to upper portion 224 via friction welding, an adhesive, or any other suitable method.
[0056] Referring to FIG. 9, it can be seen that it is possible to access the underside (inner surface) of first portion 202 so that lower portion 226 of venturi tube 216 can be affixed to upper portion 224 of venturi tube 212. The example of an air duct that is fully formed, such as shown in FIG. 5 does not present easy access to affix a portion of the venturi tube to the other portion of the ejector. Thus, in FIG. 5, flange 156 of ejector 150 and protuberance 178 and flange 176 are provided on air duct 170 from the exterior. The embodiment in FIGS. 7-10 presents a number of advantages including fewer separate parts that are assembled and obviation of two flanges (on air duct and on the ejector), thereby providing lower weight and lower material costs. The embodiment in FIGS. 7-9 is facilitated by the two-piece intake duct that is separated axially. Yet another advantage of the embodiment in FIGS. 7-9 is that is obviates the possibility of leak between the ejector and the air system component compared to the embodiment in FIG. 5 which could occur if the friction weld between the surface of ejector 150 to surface 176 is not completely sealing or if a crack in the joint were to form.
[0057] In FIGS. 7-9, the upper portion of the ejector is integral with a wall of a portion on the intake duct. In an alternative embodiment, a section 400 of an air duct has a protuberance 401 in which an upper portion of the ejector is molded. First tube 402 and second tube 404 of the ejector extend out of protuberance 401 as shown in FIG. 10. In FIG. 11, an underside of section 400 of the air duct shows the indentations that form a portion of a converging section 410, a throat 408, and a diverging section 410 of the ejector. The outlet opening 405 of tube 404 is adjacent to throat 408. Another portion 412 of the ejector that forms a venturi, when coupled to section 400, has a converging section 420, a throat 418, and a diverging section 416. Portion 412 is affixed to the portion of the ejector that is integral with portion 400 of the air duct. Converging sections 410 and 420, throat sections 408 and 418, and diverging sections 406 and 406 are mated together. These can be affixed via friction welding, an adhesive, a snap fit connection, or any suitable coupling technique.
[0058] After the ejector is made whole by coupling 412 to the ejector portion in portion 400, a second section 422 of the air duct is coupled to section 400 of the air duct, as shown assembled in FIG. 12. In the embodiment shown in FIG. 12, first tube 410 forms an acute angle 424 with the surface of first section 400 of the air duct.
[0059] In an alternative embodiment shown in FIGS. 13-15, a lower portion 454 of an ejector is integrally formed with a first section 450 of an air duct (FIG. 13). Lower portion 454 has a converging section 460, a throat 458, and a diverging section 456. First section 450 has a built up wall 452. In FIG. 14, an upper portion 468 of the ejector is coupled to first section 450 of the air duct. Upper part 468 has a flange 466 that is affixed to an upper surface of wall 452. An inner surface 453 of first portion 450 and an outer surface 451 of first portion 450 are both visible in FIG. 14.
[0060] In FIG. 15, a second section 470 of the air duct is shown coupled to first section 450. Second section 470 has an inlet 472 and an outlet 474.
[0061] In FIG. 16 ducts 302 and 304 of an ejector are shown extending outwardly from an air filter box 300. A cross section through box 300 and the ejector is shown in FIG. 17. Tubes 302 and 304 as well as an upper portion 310 of venturi tube 306 are integrally formed with box 300. A lower portion 312 of the ejector, i.e., the portion that is below line 326, which is substantially a centerline of venturi tube 306, is formed separately by injection molding, or any suitable process. Venturi tube 306 has a converging section 320, a throat 322, and a diverging section 324. Air filter box 300 and upper portion 310 are unitarily formed. Lower portion 312 is a separate component and is affixed to upper portion 310 via: friction welding, adhesion, snap fit, or any other suitable process. In FIG. 18, the ejector of FIG. 17 is shown prior to affixing lower portion 312 to upper portion 310. In FIGS. 17 and 18, the surfaces which are used to affix upper portion 310 to lower portion 312 happens to line up with centerline 326. This is nonlimiting and other designs for the affixing surfaces are within the scope of the present disclosure.
[0062] The two pieces of the ejector, one of which is integral with the air intake component, may be coupled by welding. According to an alternative embodiment, the ejector is coupled via a snap fit. In a cross-sectional view in FIG. 19, an upper piece 502 and a lower piece 504 of a portion of an ejector 500 is shown. Lower piece 504 is provided with a groove 506 in a face of lower piece 504 that interfaces with lower piece 502. An O-ring 508 is placed into groove 506. Upper piece 502 is provided with a recess 510 along an outer surface. Recess 510 does not extend all the way to the interface with lower piece 502. A lip 514 extends outwardly. Lower piece 512 is molded with a flexible finger 510 that engages with lip 514.
[0063] In another embodiment in FIG. 20, a cross section of a portion of an ejector 520 has an upper piece 522 and a lower piece 524. Upper piece 520 has a wedge 530 that extends outwardly from the surface. Lower piece 524 has a flexible finger 532 that engages with wedge 530. In the embodiment in FIG. 20, an adhesive 526 has been applied to the interface surface of upper part 522 and/or the interface surface of lower part 524. In FIGS. 19 and 20, the flexible finger is on the lower part. However, this is simply a non-limiting example. Variations of these examples are also within the scope of the disclosure.
[0064] According to embodiments of the disclosure, an intake component with an ejector affixed is simplified over prior-art ejectors. Referring to FIG. 21, an overview of the process is shown starting in block 350 when a first portion of an air intake component is formed, by injection molding in a non-limiting example. A first portion of the intake component includes first and second tubes and a first half of a venturi tube of an injector that is integrally molded. In block 352, a second portion of the ejector is formed, for example by injection molding. The second portion of the ejector includes a second half of the venturi tube. In block 354, a second portion of the air intake component is injection molded, or formed by any suitable process. In block 356, the second portion of the ejector is coupled to the first portion of the ejector. This can be via friction welding, snap fitting, or any suitable process. In block 358, the second portion of the air intake component is affixed to the first portion of the air intake component.
[0065] Referring now to FIG. 22, in block 350 a first portion of an air intake component is injection molded; the first portion includes a first half of a venturi tube of the ejector. In block 352, a second portion of the ejector is injection molded. The second portion of the ejector, in this example, includes first and second tubes and a second half of the venturi tube of the ejector. In block 354, the second portion of the air intake component is injection molded. In block 356, the second portion of the ejector is affixed to the first portion of the ejector. In block 358, the first and second portions of the intake air component. The air intake component can be an air duct, an air filter box, or any suitable air intake component.
[0066] As described herein, the ejector and air component (such as duct or air box) are manufactured via injection molding, a process that is well-known in the industry to be robust and suited for low cost and high volume. There are limitations to what kinds of shapes can be made via injection molding. It is not possible to form the ejector of FIGS. 5-18 in a single piece and retain the venturi function. In injection molding, a pin is inserted into the mold to form tubes such as tubes 302 and 304 shown in FIGS. 16-18. When ejecting the molded part from the mold, the pins are retracted from tubes 302 and 304.
[0067] Referring back to FIGS. 2 and 3 of the prior art, the tube 134 is formed via one of the pins and the opening at the end of tube 134 is sealed via plug 124.
[0068] Some unskilled in the art of injection molding might suggest that the configuration shown in FIG. 8 could be formed in a unitary fashion, i.e., that both portions of venturi tube 216 (i.e., the portion above lines 220 and 222 and the portion below lines 220 and 222) could be formed unitarily with portion 202 of the air duct 200. This is not possible for a number of reasons as will be explained in reference to FIG. 23, which is related to FIG. 8. In FIG. 23, an ejector 612 is shown unitarily formed with an air duct 600. Ejector 612 has a venturi tube that has: a converging section 606, a throat 608, and a diverging section 610. During ejection of the formed part from an injection molding machine, pins would need to be pulled in the direction of arrows 630 and 632. It would be impossible to pull a pin out at arrow 632 for two reasons: there would need to be an opening in the wall near the converging section 606 of the venturi tube. To do that, there would need to be a plug put in the wall to cover that hole that is needed for forming converging section 606. Avoiding such a plug, and the concomitant problems that it presents, is one of the things that the present disclosure is intended to overcome. Secondly, a pin cannot be pulled in the direction of arrow 632 because the wall of air duct section 602 is in the way. It is physically impossible. One would be required to fundamentally alter the shape of the air system component, thus interfering with air flow to the engine, to be able to form the shape of the converging section. Finally, as will be shown below, pulling pins to form passageways are suitable for tubes 620 and 614 of ejector 612. Passageways 620 and 614 are cylindrical and of reasonable large diameter so that the pins to form them do not stray from design standards for robust injection molding process. However, it is not suitable, to form the complicated, small diameter shape in the vicinity of throat 608 by pulling a pin. As described above, prior art ejectors that were formed with pins (impossible in the present configuration, however, can be done with an ejector that is not unitarily formed with an air system component) had many manufacturing issues: pin breakage regularly taking down the line; dimensional inconsistency and flashing leading to high part rejection rate; increased cost of production; and even inadequate supply of the ejector that brings down a vehicle assembly line.
[0069] Referring back to FIGS. 2 and 3, passageways in ejector 120 are cylindrical. Because of this insert 130 provides the geometry for the venturi effect. The complicated geometry of the converging section 606 of FIG. 23 is not possible to form robustly and with sufficient dimensional accuracy with a pin in an injection molding process.
[0070] It is known by one skilled in the art that for a robust injection molding process, the length of the pin should be less than about three times the diameter of the pin. To form throat 608, that has a small diameter, a robust pin couldn't be nearly as long as diverging section 610, let alone the entire length of air duct 600. The disclosed ejector overcomes the use of a pin, precisely for the reasons that it cannot provide the desired geometry without going far outside the known design criterion for robust injection molding.
[0071] In production, when a longer pin was used to form the throat of the venturi by pulling a pin longer than three times the diameter of the throat diameter, i.e., against well-established design guidelines, production problems ensued. The pins were replaced frequently as they were insufficiently robust for long production times between service. Secondly, there was often additional flashing (extra plastic) that was left behind at the throat, i.e., at the critical portion of the ejector to obtain the desired flow characteristics. The production of the ejectors was, at times, insufficient to keep up with the demand due to regular pin breakage and high reject rate. Of course, these production problems led to higher prices of the parts and even shutting down an entire vehicle assembly line waiting for a suitable supply of ejectors.
[0072] In FIG. 24, the flow characteristics are shown. Curve 670 indicates the standard that is required for emission control purposes, i.e., to pull enough gases through to purge the canister. One of the prior art ejectors' flow characteristics is shown as curve 660. The ejector performance does not meet the standard. It suffers from the inability to mass produce the desired venturi dimensions due to the injection molding process based on the design in which the venturi tube of the ejector is molded in a single piece. Ejectors according to embodiments disclosed herein lead to a surprising result of the flow characteristics exceeding the flow characteristics to meet the standard. In addition to the very favorable flow characteristics, the ejector made as disclosed herein, i.e., in which the venturi is made in two portions that are coupled, has proven to be more robust to manufacture with very low reject rate and reduced maintenance of the injection mold.
[0073] While the best mode has been described in detail with respect to particular embodiments, those familiar with the art will recognize various alternative designs and embodiments within the scope of the following claims. While various embodiments may have been described as providing advantages or being preferred over other embodiments with respect to one or more desired characteristics, as one skilled in the art is aware, one or more characteristics may be compromised to achieve desired system attributes, which depend on the specific application and implementation. These attributes include, but are not limited to: cost, efficiency, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. The embodiments described herein that are characterized as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.
