EP2422069A1

EP2422069A1 - Exhaust gas recirculation valve and method of cooling

Info

Publication number: EP2422069A1
Application number: EP10767639A
Authority: EP
Inventors: Oswald Baasch; Adam L. Walker
Original assignee: International Engine Intellectual Property Co LLC
Current assignee: International Engine Intellectual Property Co LLC
Priority date: 2009-04-20
Filing date: 2010-04-20
Publication date: 2012-02-29
Also published as: CN102449296A; JP2012524212A; EP2422069A4; WO2010123899A1; BRPI1013738A2

Abstract

An exhaust gas recirculation valve has a cast metal body having at least one cooling circuit that is cast in to the cast metal body. The cooling circuit includes a coolant inlet, a coolant outlet, and passage between the inlet and the outlet. Another device has a cast metal body, and electronics cooling circuit cast into the metal body, and a valve cooling circuit cast into the metal body. The electronics cooling circuit cools at least one of a circuit board and a motor. The valve cooling circuit cools at least one of a valve shaft and a gear train. A method of manufacturing an exhaust gas recirculation valve includes providing a mold having a cast pattern comprising at least one cooling circuit in the mold. The cooling circuit includes a coolant inlet, a coolant outlet, and a coolant passage between the inlet and outlet. The method further involves introducing molten metal or alloy to the mold, and cooling the molten metal or alloy, to form a cast metal device having the pattern of the mold including the cooling circuit.

Description

EXHAUST GAS RECIRCULATION VALVE AND METHOD QF COOLING

BACKGROUND

[0001] In the automotive industry exhaust gas recirculation (EGR) systems have been used to reduce the NOx emissions of engine exhaust by recycling inert exhaust gas. EGR systems may be internal, i.e., by trapping exhaust gas within the cylinder by not fully expelling it during the exhaust stroke, or external, e.g., by piping it from the exhaust manifold to the inlet manifold. EGR systems may be high pressure, such as for forced induction applications, or low pressure, such as for naturally aspirated engines. Control valves may be used as part of the EGR system to modulate and time the recirculated gas flow. Depending on the location of the modulating valve and the coupling of the driver mechanism, valves and actuators used as part of EGR systems may be exposed to high temperatures transmitted via conduction, convection or radiation.

SUMMARY

[0002] A device such as an exhaust gas recirculation valve is disclosed. In an exemplary embodiment, an exhaust gas recirculation valve has a cast metal body having at least one cooling circuit that is cast in to the cast metal body. The cooling circuit includes a coolant inlet, a coolant outlet, and passage between the inlet and the outlet.

[0003] In another embodiment, a device has a cast metal body, and electronics cooling circuit cast into the metal body, and a valve cooling circuit cast into the metal body. The electronics cooling circuit cools at least one of a circuit board and a motor. The valve cooling circuit cools at least one of a valve shaft and a gear train. [0004] In other exemplary embodiment, a method of manufacturing an exhaust gas recirculation valve includes providing a mold having a cast pattern comprising at least one cooling circuit in the mold. The cooling circuit includes a coolant inlet, a coolant outlet, and a coolant passage between the inlet and outlet. The method further involves introducing molten metal or alloy to the mold, and cooling the molten metal or alloy, to form a cast metal device having the pattern of the mold including the cooling circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] In order to facilitate a fuller understanding of the exemplary embodiments, reference is now made to the appended drawings. These drawings should not be construed as limiting but are intended to be exemplary only.

[0006] FIG. 1 is a perspective view of an EGR valve, in accordance with an exemplary embodiment.

[0007] FIG. 2 is a sectional view of an EGR valve, in accordance with an exemplary embodiment.

[0008] FIG. 3 is a sectional view of an electronics portion of an EGR valve, in accordance with an exemplary embodiment.

[0009] FIG. 4 is a sectional view of an EGR valve, in accordance with an exemplary embodiment.

[0010] FIG. 5 is a sectional view of a valve portion of an EGR valve, in accordance with an exemplary embodiment.

[0011] FIG. 6 is a sectional view of a valve portion of an EGR valve, in accordance with an exemplary embodiment. [0012] FIG. 7 is a sectional view of an EGR valve, in accordance with an exemplary embodiment.

[0013] FIG. 8 is a perspective view of an EGR valve, in accordance with an exemplary embodiment.

[0014] FIG. 9 is a sectional view of an EGR valve, in accordance with an exemplary embodiment.

[0015] FIG. 10 is a sectional view of an electronics portion of an EGR valve, in accordance with an exemplary embodiment.

[0016] FIG. 11 is a sectional view of an EGR valve, in accordance with an exemplary embodiment.

[0017] FIG. 12 is a sectional view of a shaft, in accordance with an exemplary embodiment.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0018] The following description is intended to convey a thorough understanding of the embodiments by providing a number of specific embodiments and details involving an exhaust gas recirculation (EGR) valve. It is understood, however, that the invention is not limited to these specific embodiments and details, which are exemplary only. It is further understood that one possessing ordinary skill in the art, in light of known devices, systems, and methods, will appreciate the use of the invention for its intended purposes and benefits in any number of alternative embodiments.

[0019] Conventional EGR systems employ EGR valves to modulate and time the recirculated gas flow. Depending on the location of the EGR valve and the coupling of the driver mechanism, valves and actuators used in EGR systems may be exposed to high temperatures transmitted via conduction, convection or radiation. Generally speaking, the EGR valves of the exemplary embodiments provide a cooling methodology and the means of achieving it via novel manufacturing processes and design features.

[0020] It is believed that the valves and methods of the exemplary embodiments provide an improvement over other known devices and cooling techniques. For example, when a metal or alloy actuator flange or valve housing or mechanism is not cast using the exemplary method, it requires several parts and seals to conform to specifications such as for leakage and robustness. The exemplary method simplifies the manufacture of these devices, by reducing or eliminating several machining, processing and assembly steps, also reducing the cost of processing these devices.

[0021] While the various features of the embodiments may be illustrated herein by reference to a valve body application, one having ordinary skill in the art will recognize that the embodiments may be utilized in various other devices, and are not limited to use in valve bodies. [0022] Referring to FIGS. 1 and 2, an exemplary EGR valve 100 may have a housing or body 110, a valve portion 150, and an electronics portion 140. Valve portion 150 and electronics portion 140 may be formed as a unitary part, or may be formed as a plurality of parts fastened together. In various embodiments, the valve portion 150 may include any valve type suitable for the embodiments described herein. For example, the valve can be a low pressure or high pressure type and can be of the internal (in cylinder) or external type. For example, low pressure EGR systems are generally for naturally aspirated engines while the high pressure EGR systems are for forced induction engine application. The valve may use any suitable modulation means. For example, in the exemplary embodiments, the modulation of the re-circulated gases can be accomplished by poppet valves, flapper valves, butterfly valves, gate valves, etc., and they can be pressure balanced or pressure biased according to their operation.

[0023] In exemplary embodiments, actuation of the valve can be accomplished by any suitable means. For example, an exemplary valve may be actuated manually, pneumatically, hydraulically or electrically and directly coupled, magnetically coupled or driven via levers and pushrods, etc. Exemplary valves and actuators are described in U.S. Patent Nos. 7,591,245, and

7,658,177 (both entitled "Air Valve and Method of Use"), the disclosures of which are incorporated herein by reference in their entirety.

[0024] Referring to FIGS. 1 and 2, in an exemplary embodiment, valve portion 150 may be an electronic closed coupled actuator two barrel butterfly EGR valve configured for a high pressure application. The valve portion 150 includes a gas passage 152, and a rotatable plate 154 coupled with a shaft 156. The rotatable plate 154 rotates between an open position, and a closed position in which the plate 154 provides a seal against a portion of the inner surface of the passage 152, so that there is substantially no gas flow past the plate 154. The valve portion 150 may have other various features, as necessary or desired.

[0025] The electronics portion 140 of the EGR valve 100 includes the electronic controls for the valve. The electronics portion 140 may include, for example, a circuit board 142, and a motor 144, such as a brushless DC (BLDC) motor. The electronics portion 140 may have other various features, as necessary or desired.

[0026] The EGR valve 100 may be cooled by any known or later developed cooling methodology. Exemplary cooling methods include those used for single or multi-barrel valves or stand-alone actuators that require cooling due to high temperature environmental exposure. In an exemplary embodiment, a coolant medium may be circulated through the EGR valve 100, to facilitate heat transfer. In various embodiments, the EGR valve 100 may have at least one cooling passage 200 formed within the valve housing/body 110, to provide a means for communicating the coolant medium through the valve body 110. The cooling passage 200 may have an inlet 210 and a outlet 220, for a coolant medium. The passage 200, inlet 210, and outlet 220 may be provided in any part of the valve body 110, as necessary or desired. For example, referring to FIGS. 1, 5, and 6, the inlet 210 and/or outlet 220 may be provided on the valve portion 150 of the valve 100, or referring to FIG. 8, the inlet 210 and/or outlet 220 may be provided in the electronics portion 140 of the valve 100, or any combination of the foregoing. The valve 100 may have a plurality of passages 200, inlets 210, and/or outlets 220. In exemplary embodiments, cooling passage(s) 200 are provided in close proximity to the mechanism(s) being cooled, thereby improving the cooling efficiency of the device. As used herein, "coolant medium" refers to any suitable coolant or refrigerant, including gases, liquids, nanofluids, and mixtures thereof. In an exemplary embodiment, the coolant medium may be a gas such as air, hydrogen, helium, nitrogen, carbon dioxide, etc. In another exemplary embodiment, the coolant medium may be a liquid such as water, polyalkylene glycols, ethylene glycol, diethylene glycol, propylene glycol, betaine, oils, fuels, molten metals (e.g., sodium or a sodium-potassium alloy), etc. One having ordinary skill in the art will recognize coolant materials suitable for use with the embodiments described herein. The coolant medium may be introduced to the cooling passage 200 by any suitable mechanism including pumps, etc.

[0027] In an exemplary embodiment, the cooling passage(s) 200 may provide one or more major cooling circuits, including an electronic/electric cooling circuit 240 (see FIGS. 1-4 and 8-10) and/or a valve cooling circuit 250 (see FIGS. 5-7 and 11). In exemplary embodiments, the valve cooling circuit 250 provides a cooling passage 200 through the valve body 110, in and about the valve portion 150, and the parts provided therein. For example, referring to FIGS. 5 and 6, the valve cooling circuit 250 may provide a cooling passage 200 about the shaft and motor flange. The valve cooling circuit 250 may reject the heat conducted through the shaft into the gear train 158 and shield the BLDC motor flange from heat conduction transmitted from the exhaust gases. In exemplary embodiments, the electronics/electric cooling circuit 240 provides a cooling passage 200 through the valve body 110, in and about the electronics/electric portion 140, and the parts provided therein. For example, referring to FIGS. 2 and 3, the electronics/electric cooling circuit 240 may provide a cooling passage 200 about the motor 144, and/or, referring to FIG. 4, about the electronic board 144. The electronic/electric cooling circuit 240 of the exemplary embodiments may reject heat generated at the circuit board and BLDC motor 144 as well as shield the circuit board 142 and the motor 144 from the engine underhood high temperatures. In exemplary embodiments, the one or more cooling circuits 240 and 250 may be formed by providing cooling passages 200 in the valve body/housing 210, or in the mechanism of valve portion 150, or a combination thereof.

[0028] In certain exemplary embodiments, valve 100 has both an electronic cooling circuit 240 and a valve cooling circuit 250. In some embodiments, the electronic cooling circuit 240 is in fluid communication with the valve cooling circuit 250. For example, in an exemplary embodiment a cooling passage 200 may be configured so that the coolant medium enters via the coolant medium inlet 210 and flows through the electronic cooling circuit 240 and then through the valve cooling circuit 250 (see FIG. 4), and then exits via the coolant medium outlet 220. In another exemplary embodiment the cooling passage 200 may be configured so that the coolant medium enters via the coolant medium inlet 210 and flows through the valve cooling circuit 250 and then through the electronic cooling circuit 240 and then exits via the coolant medium outlet 220. In other embodiments, separate cooling passages 200 may be provided for the electronic cooling circuit 240 and the valve cooling circuit 250, each circuit having its own cooling medium inlet 210 and outlet 220.

[0029] In exemplary embodiments, to further reduce the heat transfer from the shaft 156 into the gear train 158 and reduce the high temperature exposure of the shaft seal 160, additional heat path reduction features may be designed into the shaft 156 between the high temperature exposure and the shaft seal 160. For example, referring to FIG. 7, a hollow shaft portion 170 may be provided to reduce the heat transfer path, or, referring to FIG. 11, the shaft 156 may be cross drilled with shaft holes 172 to reduce the heat transfer path. In one exemplary embodiment, a non-contact heat transfer configuration minimizes the gap between the shaft housing and its integrated cooling passage to achieve shaft heat rejection. In other exemplary embodiments, the shaft heat rejection may be achieved with a contact heat transfer design. For example, in one embodiment, the coolant passage 200 may direct the coolant medium the shaft 156 so that it is exposed to the coolant and two shaft seals 160a and 160b contain the coolant, segregating it from the valve passage 152. In another exemplary embodiment, a shaft cooling passage 164 may be provided through the shaft 156. The shaft cooling passage 164 may be in fluid communication with the valve cooling circuit 150 and/or the electronic cooling circuit 240. In another embodiment, the hollow shaft (FIG. 7) may be a sodium-filled shaft, or may be a flow-through chamber. In yet another embodiment, referring to FIG. 12, brush contacts 162 may be spring loaded between the housing 110 and the shaft 156, whereby the brushes 162 carry the heat from the shaft to the adjacent cooled surface of the housing 110. In this embodiment, the brushes 162 may be connected to the shaft 156 (as shown) or to the adjacent housing 110. Spring loading of the brushes 162 may be accomplished by any suitable means such as, for example, compression, tension, or torsional springs 174 as well as sponge type brushes with spring properties, may be connected to the shaft 156 (as shown) or to the adjacent housing 110. [0030] In various embodiments, a method for cooling may be provided. In one embodiment, the EGR valve 100 includes one or more cast parts, and a cooling method involves providing cooling passages 200 that are "cast in" to the cast parts, such as by using a lost foam casting process, a lost core investment casting process, a salt core casting process, or the like. While the embodiments are described in more detail below with respect to a lost foam casting process, one of ordinary skill in the art would recognize from this description how to adapt other suitable processes to make a similar device.

[0031] Lost foam casting processes generally involve providing a lost foam embedded in sand mold, where the foam is formed into the desired shape of the finished cast part; and pouring molten metal or alloy material onto the vaporizable foam material so that the molten metal vaporizes and displaces the foam, forming a cast part in the shape of the lost foam. This casting process allows a reduction in assembly complexity, parts count and the potential leak points generally encountered in a multi seal assembly. Seals have also the properties in reducing the heat transfer causing poor heat rejection via the coolant and/or heat and/or fluid compatibility issues. Any suitable metal and/or alloy material may be used in the various embodiments including, for example, aluminum or cast iron.

[0032] In exemplary embodiments, the lost foam and sand mold may be configured to provide one or more cooling passages 200 in the cast part to provide one or more cooling circuits having a coolant medium inlet 210 and a coolant medium outlet 220. The method of the exemplary embodiments provides advantages over known processes because it can provide cooling passages in closer proximity to the mechanism(s) being cooled, thereby improving the cooling efficiency of the device.

[0033] In various embodiments, the lost foam material may be any foam material that is vaporizable by the molten metal or alloy to form voids therein. In an exemplary embodiment, the lost foam may be polystyrene foam. Other suitable materials for the lost foam may be used as necessary and/or desired.

[0034] In an exemplary embodiment, a single piece lost foam casting process may be utilized to maximize the coolant flow and heat rejection and minimize the part count assembly complexity and leak potential. Other variants of this process that are suitable for the embodiments described herein may be used as necessary and/or desired.

[0035] In the preceding specification, various embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments implemented, without departing from the broader scope of the exemplary embodiments as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.

Claims

What is claimed is:

1. An exhaust gas recirculation valve, comprising: a cast metal body; at least one cooling circuit that is cast in to the cast metal body, the cooling circuit comprising a coolant inlet, a coolant outlet, and coolant passage between the inlet and the outlet.

2. The exhaust gas recirculation valve of claim 1, wherein the cooling circuit is an electronics cooling circuit.

3. The exhaust gas recirculation valve of claim 2, wherein the electronics cooling circuit cools at least one of a circuit board and a motor.

4. The exhaust gas recirculation valve of claim 3, wherein the electronics cooling circuit further insulates at least one of the circuit board and the motor from external heat.

5. The exhaust gas recirculation valve of claim 1, wherein the cooling circuit is a valve body cooling circuit.

6. The exhaust gas recirculation valve of claim 5, wherein the valve body cooling circuit cools at least one of a valve shaft and a gear train.

7. The exhaust gas recirculation valve of claim 6, wherein the valve shaft conducts heat from the gear train.

8. The exhaust gas recirculation valve of claim 7, wherein the valve shaft is hollow.

9. The exhaust gas recirculation valve of claim 7, wherein the valve shaft is cross drilled.

10. The exhaust gas recirculation valve of claim 5, wherein the valve body cooling circuit further comprises at least one brush contact disposed between a valve housing and a valve shaft, the brush contact conducting heat from the valve shaft to the valve housing.

11. The exhaust gas recirculation valve of claim 10, wherein at least one brush contact is urged toward one of the valve shaft and the valve housing.

12. The exhaust gas recirculation valve of claim 10, wherein the at least one brush contact is urged by a spring.

13. The exhaust gas recirculation valve of claim 6, wherein the valve shaft comprises a shaft cooling passage.

14. A device comprising: a cast metal body; an electronics cooling circuit cast into the metal body, wherein the electronics cooling circuit cools at least one of a circuit board and a motor; and a valve cooling circuit cast into the metal body, wherein the valve body cooling circuit cools at least one of a valve shaft and a gear train;

15. The device of claim 14, wherein the electronics cooling circuit further insulates at least one of the circuit board and the motor from external heat.

16. The device of claim 14, wherein the valve shaft is hollow.

17. The device of claim 14, wherein the valve shaft is cross drilled.

18. The device of claim 14, wherein the valve body cooling circuit further comprises at least one brush contact disposed between a valve housing and a valve shaft, the brush contact conducting heat from the valve shaft to the valve housing.

19. The device of claim 14, wherein at least one brush contact is urged toward one of the valve shaft and the valve housing.

20. The device of claim 19,, wherein the at least one brush contact is urged by a spring.

21. The device of claim 20, wherein the valve shaft comprises a shaft cooling passage.

22. A method of manufacturing an exhaust gas recirculation valve, comprising: providing a mold having a cast pattern comprising at least one cooling circuit in the mold, the cast pattern comprising a coolant inlet, a coolant outlet, and a coolant passage between said inlet and outlet; introducing molten metal or alloy to the mold; cooling the molten metal or alloy, to form a cast metal device having the pattern of the mold including the cooling circuit.

23. The method of manufacture of claim 22, wherein the cooling circuit is an electronics cooling circuit.

24. The method of manufacture of claim 22, wherein the electronics cooling circuit cools at least one of a circuit board and a motor.

25. The method of manufacture of claim 22, wherein the cooling circuit is a valve body cooling circuit.

26. The method of manufacture of claim 25, wherein the valve body cooling circuit cools at least one of a valve shaft and a gear train.

27. The method of manufacture of claim 26, wherein the valve shaft conducts heat from the gear train.

28. The method of manufacture of claim 27, wherein the valve shaft is hollow.

29. The method of manufacture of claim 27, wherein the valve shaft is cross drilled.

30. The method of manufacture of claim 25, further comprising: providing at least one brush contact between a valve housing and a valve shaft, the brush contact conducting heat from the valve shaft to the valve housing.

31. The method of manufacture of claim 30, wherein at least one brush contact is urged toward one of the valve shaft and the valve housing.

32. The method of manufacture of claim 30, wherein the at least one brush contact is urged by a spring.

33. The method of manufacture of claim 26, further comprising: providing a shaft cooling passage through the valve shaft.

34. The method of manufacture of claim 22, wherein the casting process is a lost foam casting process.

35. The method of manufacture of claim 22, wherein the casting process is a lost core investment casting process.

36. The method of manufacture of claim 22, wherein the casting process is a salt core casting process.

37. A method of cooling an exhaust gas recirculation valve, comprising: providing a cast metal exhaust gas recirculation valve comprising at least one cooling circuit, the cooling circuit comprising a coolant inlet, a coolant outlet, and coolant passage between the inlet and the outlet; introducing a coolant into the coolant outlet; and cooling at least one element adjacent to the cooling circuit.

38. The method of claim 37, wherein the cooling circuit is an electronics cooling circuit.

39. The method of claim 38, wherein the element adjacent to the electronics cooling circuit comprises at least one of a circuit board and a motor.

40. The method of claim 39, wherein the electronics cooling circuit further insulates at least one of the circuit board and the motor from external heat.

41. The method of claim 37, wherein the cooling circuit is a valve body cooling circuit.

42. The method of claim 41, wherein the element adjacent to the valve body cooling circuit comprises at least one of a valve shaft and a gear train.

43. The method of claim 42, wherein the valve shaft conducts heat from the gear train.

44. The method of claim 43, wherein the valve shaft is hollow.

45. The method of claim 43, wherein the valve shaft is cross drilled.

44. The method of claim 41, wherein the valve body cooling circuit further comprises at least one brush contact disposed between a valve housing and a valve shaft, the brush contact conducting heat from the valve shaft to the valve housing.

47. The method of claim 46, wherein at least one brush contact is urged toward one of the valve shaft and the valve housing.

48. The method of claim 47, wherein the at least one brush contact is urged by a spring.

49. The method of claim 41, wherein the valve shaft comprises a shaft cooling passage.