Charge air cooler and method of assembling the same

Abstract

A charge air cooler includes a tube block having a plurality of finned tubes and a tank assembly at each end. Each of the tank assemblies includes a tank body for receiving one of the ends of the finned tubes in the tube block. A connecting plate, a heat resistant flexible gasket and a backing plate provide a first resilient seal with each of the tubes and the connecting plate. A flexible annular seal extends around the connecting plate for providing a second resilient seal between the connecting plate and the tank body. The connecting plate includes a base having a plurality of spaced tabs extending therefrom, and the tank has a plurality of spaced raised bosses around the exterior thereof adjacent the open face of the tank which are so sized and positioned as to interdigitate when the tank is assembled to the connecting plate.

Description

[0001] This nonprovisional application claims priority under 35 U.S.C. .sctn. 119(e) on U.S. provisional application No. 60/223,979, filed on Aug. 9, 2000, which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to a charge air cooler for use with internal combustion engines. More particularly, the invention relates to an improved charge air cooler assembly which is particularly well suited for large, high horsepower turbocharged diesel engines.

[0004] 2. Description of the Background Art

[0005] In recent years, charge air coolers have become rather common components on diesel engines, and particularly on large turbocharged diesel engine of the type used in commercial trucks and heavy equipment. Charge air coolers are used to cool intake air after it has been compressed by the turbocharger and before it enters the combustion chambers of the engine.

[0006] Engines which use charge air coolers achieve a significant power gain through their usage, but repair costs associated with the charge air coolers tend to be high. This is so because of the thermal and mechanical demands and stresses placed upon the charge air cooler when the engine is operated. These units typically receive incoming air which has been compressed to pressures on the order of 40 psi (pounds per square inch). Because of the heat of compression, the air is heated by the compressing of the turbocharger to temperatures on the order of 400-500.degree. F.

[0007] In order to achieve the power increases afforded by charge air cooling, it is necessary to cool the compressed air to temperatures on the order of 120.degree. F. Moreover, because the heated incoming air is generally at a rather high pressure on the order of 40 psi, the charge air cooler unit must be well sealed in order to prevent pressure losses at any seals which might be used in the units.

[0008] Sealing the charge air coolers has been a particularly vexing problem in the past. Often, the units were soldered or brazed together in the same manner as radiators had been sealed. However, such sealing techniques were quickly found to be deficient, since the result was a rather rigid structure which would be quickly damaged by thermal stresses induced by the change of temperature, and accentuated by vibrational stress from the operation of the engine. The normal vibrations of diesel engines tended to quickly cause cracks to develop in the brazed or soldered joints, and pressures began to drop early in the life of the cooler units.

[0009] Attempts to overcome this problem have sought to provide vibration damping mounts for the charge air coolers, to prevent vibrations from being transmitted to the charge air cooler units.

[0010] The finned tube units open into chambers at their ends. The finned tubes are generally made of highly heat conducting material such as aluminum in order to allow quick removal of heat from the incoming air, but these finned tubes must be connected to the tanks into which the tubes open. The tanks are generally made of cast metal such as aluminum or steel, and are therefor rather heavy components. The juncture of the finned tubes with the tanks is the location of many leaks. Because of the heat of the incoming, compressed air, the tanks are heated to essentially the same temperature as the incoming air, but the finned tubes quickly dissipate heat from the same air, and the air begins to cool immediately upon entering the finned tubes. The result is differential thermal expansion at the joint between the tank and the tubes. The thermal gradient from inlet to outlet across the charge air cooler can be on the order of 200-300.degree. F.

[0011] Unlike other heat exchange units which are mounted in a shock and vibration damping mounting arrangement, because of their size and weight, charge air coolers tend to be more rigidly mounted on and connected with the engines in order to perform their function, such that vibration damping is not possible in conventional ways, and the problems caused by vibration continue to persist in the industry. Because of the relatively high cost of the charge air cooling units, an improved charge air cooler with improved service life is greatly needed. This is particularly true since the engines generally have a long service life before overhaul is required, and having to pull an engine out of service prematurely imposes an even greater cost.

[0012] As engines have grown in horsepower output in recent years, so has the problem of leaks in the charge air coolers increased in severity. These problems are particularly severe in the case of high horsepower engines in the 500 to 700 horsepower range.

[0013] One prior technique for overcoming the differential thermal expansion problems associated with charge air coolers involved the provision of end strips having supporting fins between plural layers of coolant ducts as described in U.S. Pat. No. 6,019,169 to Ruppel, et al. Such a technique, though, increases the number of parts in the assembly, thus increasing the production cost of the charge air cooler.

SUMMARY AND OBJECTS OF THE INVENTION

[0014] Accordingly, a primary object of the present invention is to provide an improved charge air cooler which overcomes the disadvantages of prior charge air coolers.

[0015] Another object of the present invention is to provide a charge air cooler system which is provided with improved sealing between the cooling tubes and the tanks for maintaining a seal under conditions of high internal pressure.

[0016] Still another object of the present invention is to provide a charge air cooler system which is less susceptible to vibration damage.

[0017] Yet another object of the present invention is to provide a charge air cooler system which provides a combination of mechanical strength and flexible resilient sealing in order to obtain improved advantages of extended life and resistance to leakage.

[0018] Still another object of the invention is to provide an improved construction for a charge air cooler in which a continuous resilient seal is coupled with a discontinuous mechanical connection for improving the overall durability of the charge air cooler.

[0019] Yet a further object of the invention is to provide an improved construction for a charge air cooler in which multiple resilient seals are combined with a strong mechanical connection for improving the durability and service life of the charge air cooler.

[0020] Another object of the invention is to provide an improved charge air cooler in which resilient seals are utilized to overcome the differential thermal expansion, while welds are used to provide the necessary strength to the assembly.

[0021] Another object of the invention is to provide an improved method for assembling a charge air cooler which will assist in providing an improved and lasting seal between the component parts.

[0022] According to the present invention, a charge air cooler assembly is provided which utilizes a block of finned heat exchange tubes opening at opposite ends of the block. The ends of the block of tubes are connected to end tanks or manifolds in order that the hot, compressed air will enter one of the tanks, pass through the tube block where it is cooled, and exit from the tube block into the other tank before entering the engine combustion air intake.

[0023] The tube block comprises a plurality of tubes of preferably rectangular cross section, and the ends of each of the tubes extend from the block through openings in a connecting plate, through openings in a flexible resilient gasket, through openings in a rigid backing plate, and then open into one of tanks at each end. The openings in the resilient gasket are specially configured with a pair of spaced, raised ribs projecting from the body of the gasket into each tube receiving opening for contacting the tubes and providing a good seal with the tubes. During the assembly process, the backing plate and connecting plate are pressed together with the gasket in between in order to slightly compress the gasket and improve the seal against the walls of the tubes.

[0024] The connecting plate is provided with a plurality of securing tabs spaced around the periphery of the connecting plate, and the securing tabs extend from the connecting plate in the direction of the end tank. Each end tank comprises a housing open along its connecting face for receiving the ends of the tubes. The housing is provided with a plurality of raised bosses on the exterior thereof and spaced around the connecting face. The bosses are positioned such that when the connecting plate is fitted to the end tank, the tabs of the connecting plate interdigitate with the bosses on the tank.

[0025] A groove on the end face of the tank is adapted to receive an annular seal much like an O-ring between the end face of the tank and the connecting plate, and a shoulder on the end face of the tank contacts the backing plate such that as the connecting plate and the tank are pressed together, the annular seal as well as the gasket are compressed slightly in order to effectuate the seal between the tank and the tube block. A pair of mounting plates may be secured to opposite ends of the connecting plates to protect the upper and lower sides of the tube blocks.

[0026] After the end tank has been fitted onto the tube block, the securing tabs of the connecting plate are touch welded or spot welded to the tank housing around the periphery of the joint. It is not necessary that a continuous weld be provided between the connecting plate and the housing, since the fluid seal is not provided by the weld. The strength of the assembly is secured by the welds, while the fluid tight seal is provided by the combination of the gasket and the annular seal.

[0027] Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0029] FIG. 1 is an exploded view of a charge air cooler according to the present invention;

[0030] FIG. 2 is a side view of one connecting plate;

[0031] FIG. 3 is a plan view of the connecting plate of FIG. 2;

[0032] FIG. 4 is a fragmentary cross-sectional view of the connecting plate taken along line 4-4 of FIG. 3; and

[0033] FIG. 5 is a cross-sectional view of the tank on one end of an assembled charge air cooler according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0034] The charge air cooler 10 according to the present invention is shown in FIG. 1 with one end exploded for purposes of clarity. It will be understood that both ends of the charge air cooler 10 are constructed in a similar manner. The unit is seen to comprise a tube block 12 made in a well known manner and comprising a plurality of tubes 14 of a generally rectangular cross-section and having fins 16 thereon for dissipating heat. The ends of the tubes 14 extend beyond the fins 16 as shown. A connecting plate 18 is provided with a plurality of openings 20 passing therethrough and corresponding to the size and number of tubes 14 in the tube block 12. The connecting plate 18 is shown in greater detail in FIGS. 2-4.

[0035] A flexible heat resistant gasket 22 is provided with openings 24 passing through the gasket 22, and corresponding in size and number to the tubes 14 in the tube block 12. The walls of these openings 24 may be provided with a spaced pair of raised ribs encircling and engaging the tubes and enhancing the seal. A backing plate 26 is provided on the opposite side of the gasket 22, and the backing plate 26 also includes openings 28 which correspond in size, number and shape to the tubes 14 in the tube block 12. In this manner, the gasket 22 is sandwiched between the connecting plate 18 and the backing plate 26.

[0036] The charge air cooler is provided on each end with a manifold or tank 30, 30(a) having a large air passageway 32, 32a. The passageway 32 on one tank 30 is deemed the inlet and the passageway 32a on the other tank 30a is deemed the outlet, depending upon the direction of flow of the air through the charge air cooler. The tanks 30, 30a in this example are mirror images of each other, although other arrangements are contemplated. The tank 30 has one face which is open toward the tubes 14 projecting through the plates 18 and 26 and the gasket 22, such that the air flows unobstructedly from the inlet passageway 32, through the inlet tank and into and through the tubes 14 to the other tank, and then out through the outlet passageway 32a.

[0037] The gasket 22 serves to provide a seal around each of the tubes 14, and by virtue of the clamping between the backing plate 26 and the connecting plate 18, the seal is enhanced and reinforced. To provide a seal between the connecting plate 18 and the tank 30, a flexible annular seal 34 is provided between the connecting plate 18 and the tank 30, as will be described in greater detail below. Both the gasket 22 and the annular seal 34 are preferably made of a high temperature resistant rubber material, which retains its flexibility at temperatures up to about 500 degrees.

[0038] Finally, a pair of support plates 36, 38 are bolted to each of the tanks 30, 30a by bolts 37 to protect the tube block 10 and to provide a mounting surface at the top and bottom of the charge air cooler. These support plates 36, 38 also secure the ends of the charge air cooler together as a further safety feature.

[0039] As seen in FIGS. 2-4, the connecting plate 18 comprises a base 39 having a plurality of finger-like projecting tabs 40 separated by spaces 41. These tabs 40 are located around the periphery of the connecting plate 18, and are preferably equally spaced. Additionally, a semicircular recess or groove 44 may be provided to extend completely around the connecting plate 18, inside of the tabs 40. The groove 44, if used, serves as a seat on the connecting plate 18 for the annular seal 34. A semicircular groove 45 is provided on the open face of the tank for receiving the annular seal 34. An additional recess 46 is provided in the base 39 on the inside of the connecting plate 18, and the recess 46 provides a seat for the gasket 22 on the connecting plate 18. In this manner, the connecting plate 18 functions to support the entire surface of the gasket 22 on one side, while the backing plate 26 supports the other side of the gasket 22.

[0040] The tanks 30, 30a are provided around their periphery with a plurality of raised bosses 48 integrally molded or cast as part of the tanks 30, 30a. As the tanks 30, 30a are applied against the end of the tube block 12, the tabs 40 interdigitate with the bosses 48. The tabs 40 and the bosses 48 thus coact to facilitate the assembly of the tanks 30, 30a onto the tube block 12 with the seals 22, 34 and the plates 18, 26 therebetween, by positioning the tanks 30, 30a with respect to the connecting plate 18 and the backing plate 26 in order that the seal 34 not be misplaced and possibly damaged during assembly. The positioning of the components during the assembly is precisely guided by the coacting tabs 40 and bosses 48 in order to assure the integrity of the seal once the assembly is completed.

[0041] According to the improved method for assembling the charge air cooler, the connecting plate 18 having a plurality of tabs 40 spaced around the periphery thereof is first applied over the ends of the tubes 14 with the tabs 40 facing away from the tubes 14. Next, the gasket 22 is positioned over the ends of the tubes 14 and pushed snugly against the connecting plate 18. Then, the rigid steel backing plate 26 is placed over the ends of the tubes 14 and positioned against the gasket 22. The annular seal 34 is then placed in the groove 45 on the tank 30. Finally, the tank 30 and the tube block 12 are positioned together, with the tabs 40 interdigitating with the bosses 48, and the assembly is slid together. Next, pressure is applied urging the tank 30 toward the tube block 12 in order to seat and slightly compress the gasket 22 and the annular seal 34, and the tabs 40 are then touch or spot welded to the tank 30 at the bosses 48 to secure the tank 30 in position.

[0042] It is not necessary to continuously weld the entire periphery between the tank 30 and the connecting plate 18, because the function of the weld is not to seal the tank 30 as in conventional welded tanks, but rather to provide a mechanical securing of the tank 30 to the connecting plate 18. The sealing of the tank 30 in order to prevent leakage of the pressurized air is achieved by means of the heat resistant gasket 22 which provides the seal between the tubes 14 and the connecting plate 18, and by means of the heat resistant annular seal 34 which provides the seal between the connecting plate 18 and the tank 30. With this construction, if a weld should crack or break due to vibration (or any other reason), as is common in prior charge air coolers, the pressurized air is not lost through the cracked weld, since the weld is not providing the seal function. Moreover, since there are a number of such welds, the strength of the tank remains intact even with a cracked weld.

[0043] The other tank 30a is assembled in a similar manner, and the support plates 36, 38 are then bolted to the tanks 30, 30a to complete the assembly. In addition to providing a supporting structure for the charge air cooler, the support plates 36, 38 also serve as a backup safety feature to prevent the tanks from being blown off because of the high pressure air in the charge air cooler in the event that several welds crack simultaneously.

[0044] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.

Claims

What is claimed is:

1. A charge air cooler comprising: a plurality of tubes having first and second ends; a first connecting plate located around said first ends of said tubes; a first backing plate located around said first ends of said tubes; a first gasket located between said first connecting plate and said first backing plate for providing a resilient seal between each of said tubes and said first connecting plate; a first tank positioned at said first ends of said tubes; and a first sealing member extending around said first connecting plate for providing a resilient seal between said first connecting plate and said first tank.

2. The charge air cooler according to claim 1, wherein said first gasket has a plurality of openings for receiving and providing a seal with each of said tubes.

3. The charge air cooler according to claim 1, wherein said first connecting plate has a base including a first recess formed therein for receiving and supporting said first gasket and said first backing plate.

4. The charge air cooler according to claim 3, wherein said base of said first connecting plate further comprises a second recess formed therein for receiving said first sealing member.

5. The charge air cooler according to claim 4, wherein an open face of said first tank includes a groove formed therein for receiving said first sealing member.

6. The charge air cooler according to claim 1, further comprising a weld around a periphery of said first tank for providing a mechanical connection between said first tank and said first connecting plate.

7. The charge air cooler according to claim 6, wherein said weld is intermittent and discontinuous around said periphery of said first tank.

8. The charge air cooler according to claim 11 wherein said first tank includes a plurality of raised bosses around an open face thereof.

9. The charge air cooler according to claim 8, wherein said first connecting plate includes a base having a plurality of tabs extending therefrom.

10. The charge air cooler according to claim 9, wherein said tabs and said bosses are interdigitated with one an other.

11. The charge air cooler according to claim 10, further comprising a plurality of separate welds between said tabs and said bosses for providing a mechanical connection between said first tank and said first connecting plate.

12. The charge air cooler according to claim 1, wherein said tubes have fins thereon for radiating heat from said tubes.

13. The charge air cooler according to claim 1, wherein said first gasket is separate from said first sealing member.

14. The charge air cooler according to claim 1, wherein said first sealing member is a flexible annular seal.

15. The charge air cooler according to claim 1, further comprising: a second connecting plate located around said second ends of said tubes; a second backing plate located around said second ends of said tubes; a second gasket located between said second connecting plate and said second backing plate for providing a resilient seal between each of said tubes and said second connecting plate; a second tank positioned at said second ends of said tubes; and a second sealing member extending around said second connecting plate for providing a resilient seal between said second connecting plate and said second tank.

16. The charge air cooler according to claim 15, further including a pair of support plates mechanically fastened to said first tank and said second tank for connecting said first tank to said second tank.

17. The charge air cooler according to claim 15, wherein said first gasket has a plurality of openings for receiving and providing a seal with each of said tubes, and said second gasket has a plurality of openings for receiving and providing a seal with each of said tubes.

18. The charge air cooler according to claim 17, wherein said first connecting plate has a base including a first recess formed therein for receiving and supporting said first gasket and said first backing plate, and said second connecting plate has a base including a second recess formed therein for receiving and supporting said second gasket and said second backing plate

19. The charge air cooler according to claim 18, wherein said first and second tanks each include a plurality of raised bosses around open faces thereof, said first and second connecting plates each include a base having a plurality of tabs extending therefrom, and said tabs and said bosses are interdigitated with one another.

20. A method for assembling a charge air cooler comprising the steps of: providing a tube block having a plurality of finned tubes; providing a tank assembly at one end of said tube block into which said finned tubes open, said tank assembly including a tank body having a plurality of spaced raised bosses around the exterior thereof adjacent an open face of said tank body; providing a connecting plate including a base having a plurality of spaced tabs extending therefrom; providing a heat resistant flexible gasket and a backing plate; fitting said connecting plate, said heat resistant flexible gasket and said backing plate over each of the tubes at said one end of said tube block for providing a first resilient seal with each of said tubes and said connecting plate; providing a flexible annular seal extending around said open face of said tank body for providing a second resilient seal between said connecting plate and said tank body; positioning said tank body onto said tube block in such a manner that said tabs and said bosses being fit together in an interdigitated relationship; and intermittently welding said tabs and said bosses around the periphery of said tank body for establishing a mechanical connection between said tank body and said connecting plate.