Patent Publication Number: US-6340051-B1

Title: Heat exchanger with baffle plates

Description:
This patent application claims the benefit of priority under 35 U.S.C. §119(a) of Dutch Patent Application No. 1012637, filed Jul. 19, 1999. Dutch Patent Application No. 1012637 is herein incorporated herein in its entirety by reference. 
     TECHNICAL FIELD 
     The invention relates to a heat exchanger provided with a housing having an inner wall, an inlet and an outlet for passing a first heart exchange medium through the housing, having a core, comprising a series of plate-shaped fins placed at least almost parallel to each other, in which each fin is provided with pipe openings, and a bundle of pipes for passing a second heat exchange medium, and a number of baffle plates, in which each baffle plate is provided with pipe openings, in which each of the pipes extends through respective pipe openings of respective fins and respective baffle plates. 
     BACKGROUND OF THE DISCLOSURE 
     Such a heat exchanger is known from Dutch patent application 9500633. Although the known heat exchanger functions well, in some situations the operation may not be optimal. In said known heat exchanger, the baffle plates are namely situated loose against the inner wall of the housing, and the baffle plates only obtain their rigidity because the pipes pass through them. As a result, there is not only a chance that a quantity of first heat exchange medium, for instance oil, leaks through between the baffle plate and the inner wall of the housing, but there is also a chance that as a result of repetitive occurrence of pressure blasts the first heat exchange medium is subjected to, for instance during the cold start of motors, valves turn over and suchlike, unwanted bending of the baffle plates arises. 
     It is an objective of the present invention to provide a heat exchanger in which the above-mentioned problems are solved. 
     To that end, a heat exchanger of the kind mentioned above according to the present invention is characterized by filling blocks being provided, each having a bent base portion which has an outer surface, the bend of the base portion being such that the filling block closely abuts the inner wall of the housing, with a rib projecting from the base portion to the centre of the housing when placed in the housing, which rib has a central slot, in which slot a respective baffle plate is accommodated. Said filling block ensures that when a possible radial change of position occurs between the baffle plate and the inner wall of the housing, no leakage of the first heat exchange medium occurs. It is noted here that as a result of the pressure of the first heat exchange medium, the filling block is pressed against the inner wall of the housing. Furthermore the filling block increases the resistance of the baffle plates against bending, for instance as a result of pressure blasts. 
     In a preferred embodiment of a heat exchanger according to the invention, at least one of the filling blocks is made of elastic material. Preferably, the elastic material is a material that is resistant to the commonly used first heat exchange media, such as for instance mineral oils. As a result, in some cases, an improved absorbtion of pressure blasts active on the baffle plates and a further reduction of leakage is realized. 
     Preferably, at least one of the filing blocks is made of aluminum or an aluminum alloy. Said materials are extremely resistant to the commonly used first heat exchange media. 
     In order to obtain a correct pressing of the outer surface of the base portion against the inner wall of the housing, according to an embodiment of the invention, at least one of the filling blocks is provided with a spring which is situated in the slot between the baffle plate concerned and the bottom of the slot. 
     A further improved pressing of the filling block against the inner wall of the housing is obtained when the outer surface of the base portion of at least one of the filling blocks shows two different curvature radiuses R 1 , R 2 , in which R 1  is the curvature radius of the central part of the base portion, R 2  is the curvature radius of the parts of the base portion that are situated outside of the central part, R 1  being larger than R 2 . Preferably the curvature radiuses have different centres. 
     Preferably, the projecting rib is provided with a bore hole, for accommodating an attachment means for attaching a filling block to the baffle plate concerned. 
     Some embodiments of a heat exchanger according to the present invention will by way of example be described on the basis of the drawing. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     FIG. 1 schematically shows a longitudinal cross-section of a heat exchanger according to the present invention; 
     FIG. 2 shows a side view of a filling block of a heat exchanger according to the invention; 
     FIG. 3 shows a top view of FIG. 2; and 
     FIG. 4 shows a cross-section along the line IV—IV in FIG.  3 . 
    
    
     SUMMARY OF THE INVENTION 
     The heat exchanger  1  as shown in the drawing comprises a substantially cylindrical housing  2  having a core  3  accommodated in there. At the top side near a first end  4 , the housing  2  has an inlet  5  and at the opposite side  6  an outlet  7 . The inlet  5  and the outlet  7  can be connected to a supply and return lead for the first heat exchange medium, for instance oil to be cooled. During use, apart from the inlet  5  and outlet  7 , the housing  2  with the core  3  accommodated in there is entirely enclosed, and the oil can be led through the housing under high pressure. The inlet and the outlet may for that matter also be differently positioned and several inlets and/or outlets may be arranged. 
     The core  3  comprises a bundle of pipes  8  extending almost parallel to each other and in longitudinal direction of the housing  2 . On both ends of the core  3  an end plate  9  has been arranged which can fittingly be accommodated in or against the housing  2 . The pipes  8  extend through the end plates, as a result of which the ends of the pipes are open and may be connected to a supply and discharge, respectively, of a second heat exchange medium, for instance water or a cooling fluid. Between the end plates  9  a large number of fins  10  have been arranged which extend almost parallel to the end plates and to each other, through which finds the pipes  8  extend, The finds  10  therefore extend almost at right angles to the longitudinal direction of the pipes  8  and are placed at a little distance from each other. The fins  10  and the pipes contact each other closely, for instance because the pipes  8  are somewhat flared within the fins  10 , as a result of which good heat conductance between the fins  10  and the pipes  8  is guaranteed. The fins  10  and the pipes  8  may of course for that matter also be connected one to the other in a conducting manner in other ways. 
     In the cylindrical housing  2  furthermore a number of baffle plates  11  are arranged, each provided with pipe openings, which at one side abut the inner wall of the housing  2  and at the opposite side are situated at a distance from the inner wall of housing  2 . Because of this distance a window is formed. These baffle plates  11  ensure that the flow direction of the first heat exchange medium, for instance oil to be cooled, is reversed again and again, so that the first heat exchange medium as it were flows through the core  3  in a zigzag manner, as a result of which an improved heat exchange arises. The pipes  8  also extend through the baffle plates  11 , and are thus fixated in position. In case that there are no pipes  8  in the window, it regards a NTIW (no tubes in window) heat exchanger. 
     In the known heat exchanger the baffle plates lie loose against the inner wall of the housing, and the baffle plates obtain their rigidity only because the pipes pass through them. As a result there is not only a chance that a quantity of first heat exchange medium, for instance oil, leaks through between the baffle plate and inner wall of the housing, but there is also a chance that as a result of repetitive occurrence of pressure blasts the first heat exchanger medium is subjected to, for instance during the cold start of motors, valves turn over and suchlike unwanted bending of the baffle plates arises. 
     The present invention solves these problems by placing a so-called filling block  13  between the baffle plate  11  and the inner wall of the housing  2 . Said filling block  13  is shown in more detail in the FIGS. 2-4. 
     Said filling block  13  has a bent base portion  14 , having an outer surface  18 . The bend of the base portion  14  is such that the filling block closely abuts the inner wall of the housing  2 . Furthermore the filling block  13  has a rib  15  projecting from the base portion  14  of the centre of the housing  2  when placed in the housing  2 , which rib has a central slot  16 , in which slot  16  a baffle plate  11  concerned can be accommodated. Said filling block  13  ensures that when a possible radial change of position occurs between the baffle plate  11  and the inner wall of the housing  2 , no leakage of the first heat exchange medium occurs. It is noted here that as a result of the pressure of the first heat exchange medium, the filling block  13  is pressed against the inner wall of the housing  2 . Furthermore the filling block  13  increases the resistance of the baffle plates  11  against bending, for instance as a result of pressure blasts. In the flow direction, that is the direction transverse to a baffle plate  11 , the filling block  13  has a certain length which is sufficient to prevent tilting of the baffle plate and to increase the leakage resistance. 
     Preferably the filling block  13  is made of elastic material, so that in some cases an improved absorbtion of pressure blasts by the baffle plates  11  and a further reduction of leakage is realised. In this case, and also in other cases, the projecting rib  15  may possibly be provided with a bore hole  17 , for accommodating an attachment means (not shown) for attaching the filling block  13  to the baffle plate  11  concerned. It should be noted here that the elastic material is a material that is resistant to the commonly used first heat exchange media, such as for instance mineral oils which may reach a temperature of 130 degrees C. 
     An extremely suitable material for the filling block  13  is aluminum or an aluminum alloy, which are highly resistant against the commonly used first heat exchange media. In order to particularly, but not exclusively, obtain a correct pressing of the outer surface  18  of the base portion  14  against the inner wall of the housing, a spring is for instance provided which is situated in the slot  16  between the baffle plate  11  and the bottom of the slot  16 . Alternatively or additionally, the outer surface  18  of the base portion  14  may show two different curvature radiuses R 1 , R 2 , in which R 1  is the curvature radius of a central part  19  of the base portion  14 , R 2 , is the curvature radius of the parts of the base portion that are situated outside of central part  19 , R 1  being larger than R 2 . As a result an improved pressing of the filling block  13  against the inner wall of the housing  2  is obtained. Preferably the curvature radiuses R 1  and R 2  have different centres. 
     Said measures, a spring in the slot and an outer surface having different curvature radiuses, may also be applied in a filling block of elastic or another material. 
     It will be clear that the invention is not limited to the embodiment described above by way of example, but that to the expert numerous variations are possible within the scope of protection of the claims.