DESC:EXTERNAL CORNER TUBE PROTECTOR DEVICE FOR CHARGE AIR COOLER

Field of the invention

The present invention relates to a charge air cooler (CAC) and more particularly, to an external protector device for tubes in the charge air cooler (CAC) core.

Background of the invention

A Charge Air Cooler (hereinafter “CAC”) is commonly used in a turbocharged intercooled internal combustion (TCIC) engine as a part of the engine cooling system. The CAC is used to cool the heated compressed air after it has passed through a turbocharger, but before it enters the engine. The use of CAC is to increase power density of the engine and to help on controlling the emissions.

The charge air passes through the series of the tubes where the heat is dissipated through the tubes to the fins on the surface of the tubes and further to forced ambient air passing over the fin and the tubes. This heat transfer takes place by convection and conduction mode.

The CAC is made by assembling of an inlet tank and an outlet tank with a core assembly by welding or crimping the header plate flanges. The core assembly is a bunch of alternating lamina of a fin and a tube. The joints between the fins, the tubes and header plates are taken place through brazing operation by means of a brazing furnace.

Most of the heavy commercial vehicles (HCV) particularly, the tractor, trailer and tipper operating on rough roads such as mines are subjected to very heavy articulations due to off-road applications. The CAC assembly has large core sizes on account of higher heat transfer performance requirements. There can be high frequency vibrations transferred from the engine to the CAC through the chassis if the rubber mountings are not effective. The CAC assembly experiences higher intensity of the vibration and twisting loads, which results in severe fatigue at the corner tube joints.

Further, the tubes are subjected to continuous expansion and contraction as the CAC tubes are subjected to the higher temperatures ranging from 180 to 250 degrees C to the low ambient temperatures ranging from -30 to 50 degrees C causing the thermal fatigue stress. Cumulatively, the CAC tube joints at corners are heavily stressed, thus leading to the cracking issue of the corner tubes.

Accordingly, there is a need for a device to provide strength to the joints and to reduce the stresses of the CAC tube joints.

Objects of the invention

An object of the present invention is to provide a protection device for a corner tube of a charge air cooler (CAC).

Another object of the present invention is to strengthen the CAC core in the corner region.

Another object of the present invention is to eliminate the occurrence of the tube failures.

Yet another object of the present invention is to prevent leakage from end tubes and header plate brazing joints.

Still another object of the present invention is to increase the life of the CAC core thereby improving the product quality and retaining the customer faith in the product.
Summary of the invention

Accordingly, the present invention provides an external corner tube protector device (hereinafter, “CTP device”) for a charge air cooler. The charge air cooler includes a plurality of outer fins, a plurality of tubes, a header plate, a core support and a plurality of inner fins. The CTP device is fitted externally to the plurality of tubes and includes a chamfer at one end thereof that allows insertion of the CTP device by gradually pressing the plurality of outer fins and connecting with last four tubes and the header plate by a brazed joint. Each corner of the charge air cooler includes the CTP device fitted thereto. Specifically, the charge air cooler includes eight numbers of corners and eight numbers of external corner tube protector devices fitted thereto. The CTP device is in a wave type shape and size of the wave is corresponding to the size of the plurality of tubes. The CTP device with the four corner tubes of the charge air cooler collectively resist the severe stress coming due to vibration and thermal cycling loads.

Brief description of the drawings

The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein
Figure 1 shows an overview of an external corner tube protector device, in accordance with the present invention;

Figure 2 shows an isometric view of a charge air cooler with the external corner tube protector device, in accordance with the present invention;

Figure 3 shows a top view of the charge air cooler with the external corner tube protector device in an inserting position, in accordance with the present invention;

Figure 4 shows a brazed external corner tube protector device with the charge air cooler, in accordance with the present invention;
Figure 5a is a sectional view along section A-A of figure 4 showing the external corner tube protector device brazed with an outer curved surface of the tube, in accordance with the present invention;

Figure 5b is a sectional view along section B-B of figure 4 showing the external corner tube protector device brazed with a flat surface of the tube, in accordance with the present invention; and

Figure 6 shows experimental results indicating substantial reduction in stresses observed with the external corner tube protector, in accordance with the present invention.

Detailed description of the invention

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.

The present invention provides an external corner tube protector device for a charge air cooler. More particularly, the present invention provides an externally fitted tube strengthener for the charge air cooler. The external corner tube protector device of the present invention with four corner tubes of the charge air cooler collectively resist the severe stress coming due to vibration and thermal cycling loads.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate the corresponding parts in the various figures. These reference numbers are shown in the bracket in the following description.

Referring to figures from 1 to 6, an external corner tube protector device (60) (hereinafter ‘the CTP device (60)’) for a charge air cooler (100) (hereinafter ‘the CAC (100)’) in accordance with the present invention is shown. As shown in figure 2, the CAC (100) comprises a plurality of outer fins (10), a plurality of tubes (20), a header plate (30), a core support (40), a plurality of inner fins (50) and the CTP device (60).

In an embodiment, the CTP device (60) is in a wave type shape and made of cladded aluminium material. The size of the wave is corresponding to the size of the plurality of tubes (20). The CTP device (60) includes a chamfer (not numbered) at one end thereof. The chamfer provided at one end allows the easy insertion of the CTP device (60) by gradually pressing the plurality of outer fins (50) and connecting with last four tubes (20) and the header plate (30) by a brazed joint. Each corner of the CAC (100) includes the CTP device (60) fitted thereto. In an embodiment, eight numbers of CTP devices (60) are provided for eight corners of the CAC (100). However, it is understood here that the number of CTP devices (60) used for the CAC (100) may vary in other alternative embodiments of the present invention.

In accordance with the present invention, the brazed joint of the CTP device (60) with the last four tubes (20) and the header plate (30) is brazed in brazing furnace. Further, the brazed joint is configured to have a strong core at the corner to withstand all external and internal forces from the vibrations and the thermal fatigue. Additionally, the CTP device (60) is configured to increase the thickness in the local region. The CTP device (60) with the four tubes (20) collectively resists the severe stress coming due to vibration and thermal cycling loads.

The CTP device (60) is fitted externally to the CAC (100) instead of fitting internally because of the presence of the plurality of inner fins (10) and blocking of the internal air flow path through the plurality of tubes (20) which leads to an unacceptable increase in the charge air pressure drop.
In an exemplary embodiment, a finite element analysis for the charge air cooler is done to validate the effect of the CTP device (60) in addition to one of the biggest core configuration with all relevant boundary conditions. As shown in figure 6, the experimental results indicate substantial reduction in the stress levels after using the CTP device (60) in the CAC (100).

Advantages of the invention

1. The CTP device (60) provides protection to the plurality of tubes (20) of the charge air cooler (100).
2. The CTP device (60) provides enhanced strength to the plurality of tubes (20) locally thereby reducing the stress of the charge air cooler (100).
3. The CTP device (60) improves the reliability of the charge air cooler (100).
4. The CTP device (60) provides customer and manufacturer satisfaction by reducing the field warranty failures and warranty cost thereof.
5. The CTP device (60) provides protection to the corner tubes (20) from stress during vehicle articulation, vibrations and thermal fatigue.

The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the scope of the invention. ,CLAIMS:We claim:

1. An external corner tube protector device (60) for a charge air cooler (100), the charge air cooler (100) having a plurality of outer fins (10), a plurality of tubes (20), a header plate (30), a core support (40), and a plurality of inner fins (50), characterized in that,
the external corner tube protector device (60) is fitted externally to the plurality of tubes (20) and includes a chamfer at one end thereof that allows insertion of the external corner tube protector device (60) by gradually pressing the plurality of outer fins (10) and connecting with last four tubes (20) and the header plate (30) by a brazed joint,
wherein, each corner of the charge air cooler (100) includes the external corner tube protector device (60) fitted thereto.

2. The external corner tube protector device (60) as claimed in claim 1 is in a wave type shape and size of the wave is corresponding to the size of the plurality of tubes (20).

3. The external corner tube protector device (60) as claimed in claim 1, wherein the charge air cooler (100) includes eight numbers of corners and eight numbers of external corner tube protector devices (60) fitted thereto.