Abstract:
The invention relates to a heat exchanger, in particular a radiator for motor vehicles, comprising a black consisting of tubes and ribs and a lower and upper collection chamber, the lower collection chamber having several chambers which are separated from one another by partitions and between which a fluidic connection can be established. If necessary, by means of a displaceable actuator via connection orifices (17, 18, 19) that are located in a connection channel (16). According to the invention, the actuator is configured as a piston (30) that can be displaced axially between an open and a closed position and the cross-sections of the connection channel (16) and the piston (30) taper from the exterior to the interior in the vicinity of the connection orifices (17, 18, 19).

Description:
The invention relates to a heat exchanger, in particular a radiator for motor vehicles, such as that known from the applicant&#39;s DE A 100 41 122. 
     BACKGROUND 
     Radiators for motor vehicles serve for cooling an internal combustion engine and are connected to a coolant circuit which consists essentially of a radiator forward flow or engine return flow, of a radiator return flow or engine forward flow with coolant pump and of a bypass with a thermostatic valve. A multiplicity of secondary circuits, for example for a charge air cooler or an oil cooler, are connected to such a coolant circuit, the individual circuits having a different temperature level and therefore being separated from one another by means of separate chambers. The chambers are part of header boxes of the coolers and are divided off from one another by means of partitions. During the filling or emptying of the radiator of the coolant circuit, the individual chambers are to communicate with one another, so that a more rapid and a uniform filling without air inclusions and, likewise, a faster emptying are possible. 
     It was therefore proposed, in DE-A 100 41 122, to connect the individual chambers of a header box to one another by means of a duct, each chamber being fluidically connected to the duct interior via a connecting orifice. The duct of hollow-cylindrical design can have inserted in it a tubular connection piece with connecting orifices which are arranged in the same positions as the orifices in the connecting duct. By the tubular connection piece being rotated about its longitudinal axis, these orifices can, on the one hand, be brought into congruence, so that all the chambers communicate with one another, and, on the other hand, are closed by further rotation. This solution has the disadvantage that, in the closed state, the sealing off of the individual chambers with respect to one another is inadequate, because this sealing takes place only via the gap between the tubular connection piece and the duct inner wall. The selected gap must therefore be relatively small, thus resulting, in turn, in relatively high adjustment forces for adjusting this actuating member. Moreover, under certain circumstances, the use of special sealing elements of complicated configuration is required in order to obtain permanent and complete leaktightness. 
     SUMMARY 
     The object of the present invention, therefore, is to improve a heat exchanger, in particular radiator, of the type initially mentioned, in such a way that, when the actuating member is in the closed state, the chambers are sufficiently sealed off with respect to one another and can be connected to one another with a sufficient cross section. 
     According to the invention, there is a provision for the actuating member to be designed as a piston adjustable axially between an open and a closed position, and for the cross sections of the connecting duct and of the piston to be designed differently in the region of the connecting orifices. Thus, by axial displacement which requires only low adjustment forces, the piston can be brought into a discharge or a filling position, in which all the chambers communicate with one another via the connecting orifices in the connecting duct. The piston can likewise be brought by axial displacement into the closed position in which all the chambers are sealed off with respect to one another. 
     Preferably, the cross sections of the connecting duct and of the piston are designed decreasingly from a first outermost connecting orifice to a second outermost connecting orifice, the first and the second outermost connecting orifice lying opposite one another, and, if appropriate, further connecting orifices being arranged along the connecting duct between the outermost connecting orifices. 
     According to an advantageous refinement of the invention, the connecting duct is designed as a stepped duct and the piston as a stepped piston. Each step forms, in the region of the connecting orifices, annular gaps which, in the closed position, are sealed off with respect to one another and, in the open position, that is to say after the axial displacement of the stepped piston, communicate with one another. For example, with three connecting orifices, the piston has three steps forming three annular gaps which, after the retraction of the stepped piston, form a continuous gap. Advantageously, the sealing off of the annular gaps with respect to one another takes place by means of O-rings which are arranged on the stepped piston and which slide on the inner wall of the stepped duct during the axial movement of the stepped pistons. 
     According to an advantageous refinement, at least one connecting orifice is arranged in the axial direction of the piston, so that more connecting orifices can be connected than there are annular gaps. For example, four connecting orifices can then be connected to one another by means of a three-step piston. 
     According to a further advantageous refinement of the invention, portions of the connecting duct and of the piston are designed conically. In the closed position, the piston bears against the conical inner wall of the connecting duct and consequently closes the connecting orifices, the chambers thus being sealed off with respect to one another. In the open position, which is reached as a result of the axial retraction of the conical piston, there is between the outer face of the piston and the inner face of the connecting duct an annular gap which connects the connecting orifices fluidically to one another. The chambers can consequently communicate with one another. Advantageously, sealing rings or sealing ribs are arranged on the circumference of the piston and they improve sealing off, without thereby appreciably increasing the adjustment forces. The conicity is to be selected such that, on the one hand, good sealing off and, on the other hand, an easy release from the sealing-off or closed position are possible. 
     In an advantageous refinement of the invention, the piston, whether it is a stepped piston or a conical piston, has at its outer end a fastening portion which is inserted into a corresponding closing orifice in the header box. Advantageously, the fastening portion is a threaded portion on the piston and the closing orifice in the header box is a threaded bore. The piston is therefore screwed into the thread, thereby at the same time bringing about the required axial movement for reaching an open and a closed position. The rotational movement of the piston for axial adjustment may take place via a hexagon socket on the outer end face of the piston. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the invention are illustrated in the drawing and are described in more detail below. 
       In the drawing: 
         FIG. 1  shows a radiator, 
         FIG. 2  shows a header box of the radiator with a plurality of chambers, 
         FIG. 3  shows a section through a connecting duct of step-shaped design (what is known as a stepped duct) with connecting orifices, 
         FIG. 4  shows the stepped duct with an inserted stepped piston in the closed position, 
         FIG. 5  shows the stepped duct with an inserted stepped piston in the open position, 
         FIG. 6  shows a conically designed connecting duct with a conical piston in the closed position, and 
         FIG. 7  shows the conically designed connecting duct with a conical piston in the open position. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a radiator  1  with an air-cooled radiator block  2 . The radiator block  2  consists of cooling tubes  3 , in particular of flat tubes, between which corrugated ribs, not illustrated, are arranged. The radiator block  2  is closed off laterally by means of side parts  4 . The cooling tubes  3  issue into an upper header or coolant box  5  and a lower header or coolant box  6 . The inlet of the coolant takes place via an inlet connection piece  7  on the upper header box  5  and outlet takes place via an outlet connection piece  8  on the lower header box  6 . The radiator  1  can be connected to a coolant circuit, not illustrated, for an internal combustion engine of a motor vehicle and is installed with vertically arranged cooling tubes  3  in the vehicle, that is to say has the coolant flowing through it from the top downward. Further secondary circuits, not illustrated here, for example for cooling a charge air cooler or an oil cooler, can be connected to this radiator  1 . 
       FIG. 2  shows a lower header box  6  without the radiator block  2  in a top view, that is to say in a viewing direction into the interior of the header box  6  which has a rectangular base area and is delimited by two longitudinal sides  6   a ,  6   b  and two narrow sides  6   c ,  6   d . The entire box  6  is subdivided into four chambers  12 ,  13 ,  14 ,  15  by means of two longitudinal partitions  9 ,  10  and by means of a transverse partition  11 . In the region of the transverse partition  11  is arranged a connecting duct  16  having four connecting orifices  17 ,  18 ,  19 ,  29  which are connected fluidically to the chambers  12 ,  13 ,  14 ,  15 . The connecting orifice  29  is in this case arranged on the end face, that is to say in the piston axial direction, on the connecting duct. The chambers  12 ,  13 , and  14  are connected to secondary circuits, not illustrated, via coolant connections  20  and  21 . 
       FIG. 3  shows a section through the connecting duct  16  in the plane of the transverse partition  11  in  FIG. 2 . The connecting duct  16  is of step-shaped design, that is to say it is designed as a stepped duct with different diameters D 0 , D 1 , D 2 , D 3 , where D 0 &lt;D 1 &lt;D 2 &lt;D 3 . The connecting duct  16  therefore has four cylindrical portions  22 ,  23 ,  24 ,  28  which are connected to one another by means of steps  25 A,  25 ,  26 . The portion  24  is followed outwardly by a threaded bore  27 . 
       FIG. 4  shows a further stepped duct  16  with an inserted stepped piston  30  which has three cylindrical portions  31 ,  32 ,  33 ,  33 A with increasing diameters d 1 , d 2 , d 3 , d 4 . The piston  30  has at its end a threaded portion  34  which is screwed into the threaded bore  27  of the connecting duct  16 . The piston  30  has on the end face a flange  35  which serves as a stop during screwing in. The individual diameter portions  31 ,  32 ,  33 ,  33 A are connected to one another via chamfered steps  36 ,  37 ,  38 . On each diameter portion  31 ,  32 ,  33 ,  33 A are located annular grooves  39  for the reception of sealing rings, known as O-rings  40 . In the position illustrated, the piston  30  is screwed into the stepped duct up to the abutment of the flange  35  and in the region of the connecting orifices  17 ,  18 ,  19  forms with said stepped duct annular gaps  41  which, however, are sealed off with respect to one another, to the connecting orifice  29  and to the thread  34  by means of sealing rings  40 . To that extent, in the valve position shown, the chambers  12 ,  13 ,  14 ,  15  connected via the connecting orifices  17 ,  18 ,  19 ,  29  and via the connecting duct  16 , also called a connecting chamber, are sealed off, in particular tight to gas, to liquid and to pressure, with respect to one another and outwardly with respect to the thread  34 . 
       FIG. 5  shows the stepped duct  16  with the stepped piston  30  in the open position, that is to say the piston  30  is displaced axially to the right by rotation as a result of the threaded portion  34 , and the threaded portion  34  and the flange  35  project outward by the amount of the adjustment travel s. A profile  44 , for example a hexagon socket, cross slot, outer hexagon or the like, is worked into the flange  35  or the head of the piston  30 , so that the piston  30  can be rotated and consequently displaced axially by means of a wrench. Even in this extended position, the piston  30  is sealed off outwardly by means of a sealing ring  40 . The inner piston portion  31  having the smallest diameter is preferably followed by an anchoring part  45  which consists of two elastically deformable legs  45   a ,  45   b  with end latching noses which form a stop during the extension of the piston. In the open position of the piston  30 , as illustrated, the annular gaps  41 ,  42 ,  43  are connected to one another and thus form a continuous annular gap, into which the connecting orifices  17 ,  18 ,  19 ,  29  issue. To that extent, in the valve position shown, the chambers  12 ,  13 ,  14 ,  15  connected via the connecting orifices  17 ,  18 ,  19 ,  29  and via the connecting duct  16  are connected to one another and continue to be sealed off outwardly with respect to the thread  34 . The corresponding chambers can consequently communicate with one another. The annular gap  41  is followed inwardly by a further annular chamber  46  via which a fluid connection to the chamber  15  of the header box  6  can be made. 
     The adjustment of the piston  30  to the closed position according to  FIG. 4  takes place in that the threaded portion  34  of the piston  30  is screwed into the threaded hole  27 . In this case, the piston  30  moves to the left in the drawing, until the O-rings  40  come into contact again with the inner wall of the stepped duct  16  and consequently bring about sealing off between the individual annular gaps  41 ,  42 ,  43  again. 
       FIG. 6  shows a further exemplary embodiment of the invention, specifically in the form of a conically designed connecting duct  50  and a conically designed piston  51 , the connecting orifices again being designated by  17 ,  18 ,  19 ,  29 . The connecting duct  50  has a conical portion  50   a , the narrowest cross section of which is followed by a cylindrical portion  50   b  which issues into the chamber  15  via the connecting orifice  29 . A further cylindrical portion  50   c , into the outer region of which an internal thread  50   d  is worked, follows on the side of the largest cross section of the conical portion  50   a . The piston  51  has a head  51   a  which is designed in a similar way to the previous exemplary embodiment, that is to say with a threaded portion, a flange, an inner profile and a sealing ring  40  which slides on the inner wall of the cylindrical portion  50   c . The head  51   a  of the piston is followed behind the O-ring  40  by a conical piston portion  51   b  which bears over its full circumference and over the entire length against the inner wall of the conical portion  50   a  of the connecting duct  50 . The connecting orifices  17 ,  18 ,  19 ,  29  are consequently closed and the chambers connected to them are separated from one another. 
       FIG. 7  shows the exemplary embodiment according to  FIG. 6  with the piston  51  displaced, that is to say the piston is screwed out of the connecting duct  50  by the amount of the adjustment travel x, but is still sealed off by means of the O-ring  40 . Between the conical portion  50   a  and the conical part  51   b  of the piston  51 , a “conical” annular gap  52  with a diameter increasing from the inside outward has arisen. As a result, the connecting orifices  17 ,  18 ,  19 ,  29  can communicate with one another, that is to say, likewise, the chambers assigned to them. The conical piston portion  51   b  has on its circumference a plurality of sealing rings  53  which are arranged one behind the other and which seal it off more effectively with respect to the inner wall of the conical portion  50   a  and consequently also bring about an effective sealing off of the connecting orifices  17 ,  18 ,  19 ,  29  with respect to one another in the closed position of the piston  51 . The adjustment of the piston  51  into the closed position takes place by the piston head  51   a  being screwed into the thread  50   d  by the amount of the travel x, the piston once again being moved up to a stop. Possible tolerance overlaps are compensated by the elasticity of the sealing rings  53 . 
     The present invention has been described by the example of a heat exchanger. It is pointed out, however, that the valve arrangement according to the invention may also be used elsewhere. In particular, the valve arrangement or the heat exchanger according to the invention is suitable both for liquid and for gaseous fluids. The heat exchanger according to the invention can be used particularly as a charge air cooler, oil cooler or heater, preferably for air, land and/or ocean vehicles. 
     REFERENCE NUMERALS 
     
         
           1  Radiator 
           2  Radiator block 
           3  Flat tubes 
           4  Side part 
           5  Upper header box 
           6  Lower header box 
           7  Inlet connection piece 
           8  Outlet connection piece 
           9  Longitudinal partition 
           10  Longitudinal partition 
           11  Transverse partition 
           12  Chamber 
           13  Chamber 
           14  Chamber 
           15  Chamber 
           16  Connecting duct 
           17  Connecting orifice 
           18  Connecting orifice 
           19  Connecting orifice 
           20  Coolant connection 
           21  Coolant connection 
           22  Stepped portion (D 1 ) 
           23  Stepped portion (D 2 ) 
           24  Stepped portion (D 3 ) 
           25  Step 
           25 A Step 
           26  Step 
           27  Threaded bore 
           28  Sealing portion 
           29  Connecting orifice 
           30  Stepped piston 
           31  Piston portion (d 1 ) 
           32  Piston portion (d 2 ) 
           33  Piston portion (d 3 ) 
           33 A Piston portion (d 4 ) 
           34  Threaded portion 
           35  Flange 
           36  Step 
           37  Step 
           38  Step 
           39  Annular groove 
           40  Sealing ring 
           41  Annular gap 
           42  Annular gap 
           43  Annular gap 
           50  Connecting duct (conical) 
           50   a  Conical portion 
           50   b  Cylindrical portion, inside 
           50   c  Cylindrical portion, outside 
           50   d  Internal thread 
           51  Piston 
           51   a  Head 
           51   b  Conical portion 
           52  Annular gap (conical) 
           53  Sealing rings