Abstract:
An exhaust heat recovery device includes a multi-piece, chamber-shaped branching member with a draw-molded first chamber half having one inlet for introducing exhaust gas, and a draw-molded second chamber half having two outlets for discharging the exhaust gas. The draw-molded first and second chamber halves are integrally connected together to form a single chamber. A first flow channel extends from one of the two outlets of the branching member for circulating the exhaust gas. A heat exchanger is provided to the first flow channel for recovering potential heat of the exhaust gas. A second flow channel extends from the other one of the two outlets of the branching member for circulating the exhaust gas while bypassing the heat exchanger. A valve chamber houses a valve configured to open and close an outlet of the second flow channel.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an exhaust heat recovery device for recovering heat from an exhaust emission or gas. 
     BACKGROUND OF THE INVENTION 
     An internal combustion engine is designed to burn fuel to generate heat energy and to obtain power by converting the generated heat energy into kinetic energy. Not all of the heat energy can be converted to kinetic energy, because a portion of the heat energy is discharged into the atmosphere in the form of exhaust gas. The loss of heat energy through the exhaust gas reduces the efficiency of the internal combustion engine. A technique is known in which an exhaust heat recovery device is attached to the exhaust pipe, and a portion of the heat energy is recovered from the exhaust gas by the exhaust heat recovery device. 
     Japanese Patent Application Laid-Open Publication No. 2009-30569, for example, discloses an exhaust heat recovery device. The structure of this exhaust heat recovery device is described with reference to  FIG. 13  hereof. 
     As shown in  FIG. 13 , the exhaust heat recovery device  100  is composed of a bypass flow channel  101  for circulating exhaust gas, the bypass flow channel being connected to an exhaust pipe extending from an internal combustion engine; a branching channel  103  branched at a right angle to the axis of the bypass flow channel  101  from the vicinity of an inlet  102  of the bypass flow channel  101 ; a valve  105  capable of opening and closing, for blocking an outlet  104  of the bypass flow channel  101 ; a valve shaft  106  for rotating the valve  105 ; a curved pipe  107  which extends from the valve  105 ; a case  108  for housing the bypass flow channel  101 , the valve  105 , and the curved pipe  107  at once; an exhaust heat recovery flow channel  111  for circulating the exhaust gas fed from the branching channel  103 , the exhaust heat recovery flow channel being formed in the case  108 ; and a heat exchanger  112  which fits in the exhaust heat recovery flow channel  111 . The bypass flow channel  101  is a flow channel for bypassing the heat exchanger  112 . 
     The medium of the high-temperature side of the heat exchanger  112  is the exhaust gas, and the medium of the low-temperature side is a coolant of the internal combustion engine. 
     The valve shaft  106  for supporting the valve  105  is urged toward the valve-closing side by a torsion spring. When the flow rate of exhaust gas through the bypass flow channel  101  is high, the gas pressure overcomes the urging force of the torsion spring. As a result, the valve is opened. When the flow rate of exhaust gas is low, the valve is closed by the action of the torsion spring. 
     The valve shaft  106  is also rotated by a thermo-actuator via the torsion spring. The coolant for cooling the internal combustion engine is passed through the thermo-actuator. When the coolant is at a high temperature, the valve shaft  106  is rotated toward the valve-open side by the thermo-actuator, and when the coolant is at a low temperature, the valve shaft  106  is rotated toward the valve-closed side. 
     The coolant is at a low temperature when the internal combustion engine is started. The flow rate of exhaust gas is low during idling. The valve is closed under these conditions. Exhaust gas flows to the exhaust heat recovery flow channel  111  without flowing to the bypass flow channel  101 . Heat is recovered by the heat exchanger  112 , and the coolant is heated. 
     When the flow rate of exhaust gas is high even at startup of the internal combustion engine, the valve opens and the exhaust gas flows to the bypass flow channel  101 . The bypass flow channel  101  has minimal flow channel resistance, and is therefore capable of circulating a large amount of exhaust gas. 
     The coolant reaches a high temperature once operation has continued for a certain amount of time. The valve is opened by the action of the thermo-actuator, and the exhaust gas flows to the bypass flow channel  101 . The reason for this is that there is no need for the coolant to be warmed by the heat exchanger  112  when the coolant is at a high temperature. 
     The case  108  is formed by welding together two case halves that are divided in the front-back direction of the drawing. Before welding, the bypass flow channel  101 , the valve  105 , the valve shaft  106 , and the heat exchanger  112  are placed in a case half. A first seal  113  is wrapped around the branching channel  103 , and a second seal  114  is wrapped around the bypass flow channel  101 . The other case half is then placed over the first case half, and the case halves are welded together. 
     Leakage and backflow of exhaust gas are prevented by the first seal  113  and/or the second seal  114 . 
     The first seal  113  and/or the second seal  114  cannot be replaced after the case halves are welded together. However, the first seal  113  and/or the second seal  114  become worn over the course of operation. As wear progresses, the sealing ability of the seals decreases, and backflow of exhaust gas occurs. Assembly is also made inconvenient by the labor of packing the bypass flow channel  101 , heat exchanger  112 , and other components in the case halves and then welding the case halves. As a result, the cost of the exhaust heat recovery device increases, and the use of exhaust heat recovery devices is less easily adopted. 
     In order to promote the use of exhaust heat recovery devices, there is a need for an exhaust heat recovery device that is easily assembled. 
     When the exhaust heat recovery device  100  is mounted in a vehicle having significant space limitations, a curved pipe  115  is frequently connected to the inlet of the bypass flow channel  101 . The use of a curved pipe  115  enables the duct length to be maintained in a limited space. When a curved pipe  115  is used, a portion of the exhaust gas impinges on the inside surface of the bypass flow channel  101 , as indicated by the arrow ( 1 ) in  FIG. 13 . This impingement causes the flow to become disordered, and there is a risk of inability to maintain the flow rate of the exhaust gas. 
     There is therefore a need for an exhaust heat recovery device in which a smooth flow of exhaust gas is maintained even when a curved pipe is connected to the inlet. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a structure for an exhaust heat recovery device that is easy to assemble. 
     Another object of the present invention is to provide an exhaust heat recovery device in which a smooth flow of exhaust gas is maintained even when a curved pipe is connected to an inlet. 
     According to an aspect of the present invention, there is provided an exhaust heat recovery device which comprises: a multi-piece chamber-shaped branching member having one inlet for introducing exhaust gas and two outlets for discharging the exhaust gas; a first flow channel, extending from one of the two outlets, for circulating the exhaust gas; a heat exchanger, provided to the first flow channel, for recovering potential heat of the exhaust gas; a second flow channel, extending from other one of the two outlets, for circulating the exhaust gas while bypassing the heat exchanger; and a valve chamber for housing a valve designed to open and closing the outlet of the second flow channel, wherein the multi-piece branching member comprises a single chamber formed by joining together a first chamber half in which one inlet is provided, the first chamber half being draw-molded from a blank, and a second chamber half in which two outlets are provided, the second chamber half being draw-molded from a blank. 
     The multi-piece branching member is obtained by welding together the draw-molded first chamber half and the draw-molded second chamber half. Since draw molding and welding are easily performed, the manufacturing cost of the exhaust heat recovery device can be minimized. 
     Assembly is accomplished merely by connecting the first flow channel and second flow channel to the branching member. The heat exchanger is preferably provided to the first flow channel in advance. An easily assembled exhaust heat recovery device is thus provided. 
     In a preferred form, the exhaust heat recovery device further comprises a merging member, provided between the outlet of the first flow channel and the valve chamber, for circulating the exhaust gas from the first flow channel to the valve chamber while the merging member comprises a single chamber formed by joining together a third chamber half in which two inlets are provided, the third chamber half being draw-molded from a blank, and a fourth chamber half in which one outlet is provided, the fourth chamber half being draw-molded from a blank. 
     The merging member has a multi-piece construction and is obtained by welding together the draw-molded third chamber half and the draw-molded fourth chamber half. Since draw molding and welding are easily performed, the manufacturing cost of the exhaust heat recovery device can be minimized. 
     Preferably, the heat exchanger has an inlet directly connected to the branching member, and the heat exchanger has an outlet directly connected to the merging member. 
     Since the heat exchanger is directly connected to the branching member and the merging member, there is no need to provide a member between the branching member and the heat exchanger, and there is no need to provide a member between the heat exchanger and the merging member. 
     It is desirable that the outlet of the second flow channel have an outside diameter larger than the outlet of the merging member. It is also desirable that the valve chamber have an inside diameter larger than a diameter of the outlet of the merging member while the second flow channel have a distal end passing through the outlet of the merging member and into the valve chamber. 
     Exhaust gas the flows through the second flow channel is discharged to the valve chamber. The inside diameter of the valve chamber is larger than the diameter of the outlet of the merging member. Specifically, the diameter of the outlet of the merging member is smaller than the inside diameter of the valve chamber. The outlet of the merging member is constricted with respect to the valve chamber. Since the outlet of the merging member is constricted, the exhaust gas in the valve chamber does not readily flow back to the merging member. A smooth flow of exhaust gas is thus achieved. 
     It is preferable that the inlet of the branching member be positioned so that a central axis of the inlet substantially coincides with a central axis of the other outlet, a curved pipe for introducing the exhaust gas be provided to the inlet, and the other outlet form a reducer part with an inside diameter decreasing along the flow of the exhaust gas, an inlet diameter of the reducer part being larger than an inside diameter of the curved pipe. 
     The curved pipe causes the flow of exhaust gas to be angled with respect to the central axis of the inlet of the branching member. In this state, the exhaust gas flows into the branching member. Since the reducer part has a large inlet diameter, exhaust gas is lead to the reducer part despite flowing at an angle. Specifically, a smooth flow of exhaust gas is maintained despite the connection of the curved pipe to the inlet. 
     Preferably, the central axis of the one outlet is offset toward the heat exchanger from the central axis of the inlet. 
     Even when the exhaust gas flows at an angle into the branching member toward the heat exchanger, since the other outlet is positioned toward the heat exchanger, the exhaust gas smoothly reaches the other outlet. A smooth flow of exhaust gas is maintained. 
     Desirably, inclination angles of the inside surfaces of the reducer part with respect to the central axis of the other outlet are configured so that the inclination angle of the inside surface that is closer to the heat exchanger is greater than the inclination angle of the inside surface that is farther from the heat exchanger. 
     Of the inclination angles of the inside surfaces of the regulator, the inclination angle of the inside surface that is closer to the heat exchanger is larger. Even when the exhaust gas flows at an angle into the branching member toward the heat exchanger, when the inside surface has a large inclination angle, there is no risk of the flow of exhaust gas becoming disordered. A smooth flow of exhaust gas is thereby maintained. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain preferred embodiments of the present invention will be described in detail below, by way of example only, with reference to the accompanying drawings, in which: 
         FIGS. 1A through 1F  are schematic views illustrating the process for manufacturing a branching member according to the present invention; 
         FIG. 2  is an exploded view showing an exhaust heat recovery device according to the present invention; 
         FIG. 3  is a sectional view showing the exhaust heat recovery device; 
         FIG. 4  is a perspective view showing the exhaust heat recovery device; 
         FIG. 5  is an enlarged view of portion  5  of  FIG. 3 ; 
         FIG. 6  is a sectional view taken along line  6 - 6  of  FIG. 3 ; 
         FIG. 7  is a view showing an operation of a second flow channel; 
         FIG. 8  is a view showing the operation of a first flow channel; 
         FIG. 9  is a view showing the operation of the heat exchanger; 
         FIG. 10  is an enlarged view of portion  10  of  FIG. 9 ; 
         FIG. 11  is a view showing a modification of the exhaust heat recovery device of  FIG. 3 ; 
         FIG. 12  is a view showing a modification of the exhaust heat recovery device of  FIG. 11 ; and 
         FIG. 13  is a sectional view showing a conventional exhaust heat recovery device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in  FIG. 1A , a blank  11  and a blank  12  are provided. 
     A draw-molded article  13  and a draw-molded article  14  are then obtained by a draw-molding process, as shown in  FIG. 1B . 
     The draw-molded article  13  and the draw-molded article  14  are then trimmed by cutting along cutting lines  15 ,  16 ,  17 ,  18 , as shown in  FIG. 1C . 
     By the process described above, the first chamber half  21  and second chamber half  22  shown in  FIG. 1D  are obtained. The first chamber half  21  is composed of a first bottom  23  and a first wall  24  that stands upright on the periphery of the first bottom  23 . An inlet  25  is provided in the first bottom  23 . The second chamber half  22  is composed of a second bottom  26  and a second wall  27  that stands upright on the periphery of the second bottom  26 . One outlet  28  and another outlet  29  are provided to the second bottom  26 . Exhaust gas for heat recovery is discharged from the one outlet  28 . 
     As shown in  FIG. 1E , the second chamber half  22  is fitted in the first chamber half  21 . A mating part  31  is then bonded using a welding torch  32 . 
     As shown in  FIG. 1F , a multi-piece chamber-shaped branching member  33  is obtained. 
     The constituent elements of the exhaust heat recovery device  40  of the present invention will be described based on  FIG. 2 . 
     As shown in  FIG. 2 , the exhaust heat recovery device  40  is composed of the multi-piece branching member  33 ; a first flow channel  41  connected to the one outlet  28  of the branching member  33 ; a heat exchanger  42  provided to the first flow channel  41 ; a second flow channel  43  connected to the other outlet  29  of the branching member  33 ; a valve  44  for blocking an outlet of the second flow channel  43 ; a merging member  45  connected to the first flow channel  41  and second flow channel  43 ; and a valve chamber  46  for surrounding the valve  44  connected to the merging member  45 . An outlet of an exhaust pipe extending from an internal combustion engine is connected to the inlet  25  of the branching member  33 . However, in this example, an introduction member  47  is connected to the inlet  25 , and the outlet of the exhaust pipe is connected to the introduction member  47 . 
     The heat exchanger  42  is composed of a core case  48 ; an entrance-side end plate  49  for blocking an inlet of the core case  48 ; an exit-side end plate  51  for blocking an outlet of the core case  48 ; a plurality of heat transfer tubes  52  housed in the core case  48  so as to penetrate through the entrance-side end plate  49  and the exit-side end plate  51 ; an entrance-side extension  53  which extends toward the branching member  33  from the entrance-side end plate  49 ; and an exit-side extension  54  which extends toward the merging member  45  from the exit-side end plate  51 . The entrance-side extension  53  and the exit-side extension  54  each serve as a first flow channel  41 . High-temperature exhaust gas flows into the heat transfer tubes  52 . Low-temperature coolant is circulated outside the heat transfer tubes  52 . The heat of the exhaust gas moves to the coolant via the heat transfer tubes  52 . The temperature of the exhaust gas decreases, and the temperature of the coolant increases. Waste heat is thus recovered. 
     The second flow channel  43  comprises a straight metal tube. The sealing ability of the valve  44  is increased by providing a retainer member  50  to the outlet of the second flow channel  43 . 
     The merging member  45  has a multi-piece construction and is manufactured by the same process as the branching member  33 . Since  FIGS. 1A through 1F  can be referred to for this process, no further description thereof will be given. 
     The merging member  45  is a chamber provided with two inlets  55 ,  56  and one outlet  57 . Specifically, the merging member  45  is composed of a third chamber half  58  which is provided with two inlets  55 ,  56 , and a fourth chamber half  59  which is provided with one outlet  57 . 
     The valve chamber  46  is a metal tube having a larger inside diameter than the outlet  57 . 
     The method of assembly will next be described. 
     The introduction member  47  is inserted in the inlet  25  of the branching member  33 . 
     The entrance-side extension  53  corresponding to the inlet of the first flow channel  41  is inserted in the one outlet  28  of the branching member  33 . The exit-side extension  54  corresponding to the outlet of the first flow channel  41  is inserted in one inlet  55  of the merging member  45 . 
     A means must be devised to attach the second flow channel  43 . Specifically, the second flow channel  43  is inserted in the merging member  45  so as to pass through the outlet  57  and other inlet  56  of the merging member  45 . The inlet of the second flow channel  43  is also inserted in the other outlet  29  of the branching member  33 . 
     The inlet of the valve chamber  46  is placed against (touching) the outlet of the merging member  45 . 
     As shown in  FIG. 3 , the introduction member  47  is joined to the branching member  33  by a first bead  61 , the entrance-side extension  53  is joined to the branching member  33  by a second bead  62 , and the exit-side extension  54  is joined to the merging member  45  by a third bead  63 . The inlet of the second flow channel  43  is joined to the branching member  33  by a fourth bead  64 , and the outlet of the second flow channel  43  is joined to the merging member  45  by a fifth bead  65 . The valve chamber  46  is joined to the merging member  45  by a sixth bead  66 . 
     Pre-welding assembly is completed by placing against or inserting the first flow channel  41 , second flow channel  43 , and valve chamber  46  into the chamber-shaped branching member  33  and chamber-shaped merging member  45 . After this assembly, the welding is performed merely by joining together the first through sixth beads  61  through  66 , and is therefore easily performed. Assembly is thereby facilitated. 
     The overall form of the exhaust heat recovery device  40  will next be described based on  FIG. 4 . 
     As shown in  FIG. 4 , a valve shaft  67  passes over the valve chamber  46 . A disc  69  is attached to one end of the valve shaft  67  via a torsion spring  68 . A lever  71  extends from the disc  69 , and a rod  73  of a thermo-actuator  72  is connected to the lever  71 . The thermo-actuator  72  is mounted on the heat exchanger  42 . 
     The coolant is introduced from a medium inlet  74  of the thermo-actuator  72 . The coolant exits from a medium outlet  75  after heating or cooling a thermal wax housed in the thermo-actuator  72 . In the event that the coolant reaches a high temperature, the thermal wax expands, and the rod  73  advances as indicated by the arrow ( 2 ). This advancing causes the lever  71  to rotate as indicated by the arrow ( 3 ), and the valve shaft  67  also rotates via the torsion spring  68  in the direction indicated by the arrow ( 3 ). 
     The relevant parts of  FIG. 3  will be described based on  FIGS. 5 through 7 . 
     As shown in  FIG. 5 , the outside diameter of the outlet of the second flow channel  43  is larger than the diameter of the outlet  57  of the merging member  45 . Exhaust gas flows from the merging member  45  to the valve chamber  46  through a gap that corresponds to half the difference in diameter. The inside diameter of the valve chamber  46  is larger than the diameter of the outlet  57  of the merging member  45 , and a distal end of the second flow channel  43  passes through the outlet  57  of the merging member  45  and into the valve chamber  46 . During exhaust heat non-recovery, the exhaust gas flows into the valve chamber  46  from the second flow channel  43 . The exhaust gas at this time preferably does not flow back into the merging member  45  from the valve chamber  46 . As shown in  FIG. 5 , the outlet  57  of the merging member  45  is constricted with respect to the valve chamber  46 . Since the outlet is constricted, there is no risk of backflow of the exhaust gas of the valve chamber  46  into the merging member  45 . An end part  76  of the second flow channel  43  is also subjected to a tube expansion process so that the outside diameter of the end part  76  is larger than the diameter of the outlet  57 . Since the end part  76  is curved so as to approach the inside surface of the valve chamber  46 , backflow of the exhaust gas is further prevented. 
     As shown in  FIG. 6 , the valve shaft  67  is supported by the valve chamber  46  so as to be able to rotate. Exhaust gas is prevented from leaking to the outside by seal rings  77 ,  77 . The valve  44  is fixed to the valve shaft  67  by bolts  78 ,  78 . 
     The outlet  57  is provided so as to cover one-half the circumference of the second flow channel  43 . The end part  76  of the second flow channel  43  is fitted in the outlet  57 . Giving the outlet  57  a length of one-half circumference ensures a degree of freedom in assembling the fourth chamber half  59  in the second flow channel  43 . When the length exceeds one-half circumference, the second flow channel  43  is moved only in the front-back direction of the drawing, and the degree of freedom is reduced. A length of less than one-half circumference may cause the exhaust gas in the valve chamber  46  to flow back. 
     An operation of the exhaust heat recovery device  40  configured as described above will next be described. 
     During acceleration or travel, when the flow rate of exhaust gas discharged from the internal combustion engine is high, the valve  44  is opened by the pressure of the exhaust gas, as shown in  FIG. 7 . The flow channel resistance of the second flow channel  43  is low. The second flow channel  43  is capable of accommodating a large flow of exhaust gas. Since the valve shaft  67  is rotated against the torsion spring by the pressure of the exhaust gas, a valve-open state occurs regardless of the position of the rod  73  of the thermo-actuator  72 . 
     When the temperature of the coolant for cooling the internal combustion engine is high, the rod  73  in  FIG. 7  advances, the valve shaft  67  is rotated via the torsion spring, and a valve-open state occurs. In the valve-open state, exhaust gas flows into the second flow channel  43 , and no heat recovery takes place. Since one purpose of heat recovery is to warm the coolant, heat recovery is not performed when the coolant is already at a high temperature. 
     When the flow rate of exhaust gas is low and the temperature of the coolant is low, the rod  73  retreats, and the second flow channel  43  is closed by the valve  44  as shown in  FIG. 8 . 
     The exhaust gas flows through the first flow channel  41 , as shown in  FIG. 9 . Heat is exchanged by the heat exchanger  42 , and the heat of the exhaust gas is transferred to the coolant. 
     As shown in  FIG. 10 , the outlet  29  is formed in a curved shape by draw-molding. When the second flow channel  43  is placed against a flat plate and fillet welded, a bead is formed at the location of maximum stress. There is a risk of cracks forming in the fillet weld due to repeated temperature variations. 
     Forming in a curved shape as shown in  FIG. 10  makes it possible to position the fourth bead  64  away from the location of maximum stress. The stress at the fourth bead  64  can be reduced. The same reduction in stress occurs at the first through third beads and at the fifth bead. 
     A modification of the configuration shown in  FIG. 3  will be described based on  FIG. 11 . In  FIG. 11 , elements that are the same as those in  FIG. 3  are referred to by the same symbols as in  FIG. 3 , and no description thereof will be given. 
     As shown in  FIG. 11 , in the branching member  33 , the central axis  25   a  of the inlet  25  of the branching member  33  substantially coincides with the central axis  29   a  of the other outlet  29 . A curved pipe  79  for introducing exhaust gas is connected to the inlet  25 . The other outlet  29  forms a reducer part  80 , the inside diameter of which decreases along the flow of exhaust gas, and the inlet diameter of the reducer part  80  is larger than the inside diameter of the curved pipe  79 . 
     The curved pipe  79  causes the exhaust gas to flow along an inclined line  81 . The inclined line  81  is inclined with respect to the central axis  25   a  of the inlet  25 . In this state, the exhaust gas flows into the branching member  33 . Since the reducer part  80  has a large inlet diameter, exhaust gas is lead to the reducer part  80  despite flowing at an angle. Specifically, a smooth flow of exhaust gas is maintained despite the connection of the curved pipe  79  to the inlet  25 . 
     The outlet of the reducer part  80  has a small or reduced diameter, and the second flow channel  43  is connected to this outlet. The second flow channel  43  also has a small or reduced diameter and is recessed by an amount δ from a line  82  connecting the inlet of the reducer part  80  and the valve chamber  46 . On-board equipment and the like can be placed in the depression thus formed. 
     It should also be noted that the first chamber half  21  is tapered by causing it to be partially curved or depressed toward the heat exchanger  42  by a distance a. By provision of the tapered part, it becomes possible to increase the rigidity of the branching member  33  and to make the exhaust gas flow uniformly and smoothly during heat recovery. The size of the heat recovery device can be reduced by the amount α. 
     The central axis  29   a  of the other outlet  29  is preferably offset an amount β toward the heat exchanger  42  from the central axis  25   a  of the inlet  25 . 
     Even when the exhaust gas flows in toward the heat exchanger  42  along the inclined line  81 , since the other outlet  29  is positioned toward the heat exchanger  42 , there is no risk of the exhaust gas leaving the other outlet  29 . 
     In the reducer part  80 , the inclination angles θ 1 , θ 2  of the inside surfaces of the regulator with respect to the central axis  29   a  of the other outlet  29  are preferably configured so that the inclination angle θ 2  of the inside surface that is closer to the heat exchanger  42  is greater than the inclination angle θ 1  of the inside surface that is farther from the heat exchanger  42 . 
     The inside surface having the inclination angle θ 2  intersects with the inclined line  81 , and the angle of intersection is near 90°. The exhaust gas that flows along the inclined line  81  thus flows against the inside surface having the inclination angle θ 2 . The exhaust gas is then guided by this inside surface toward the second flow channel  43 . Specifically, even when the exhaust gas flows at an angle into the branching member  33  toward the heat exchanger  42 , when the inside surface has a large inclination angle, flow of the exhaust gas into the first flow channel  41  can be prevented and pressure loss can be reduced. A smooth flow of exhaust gas is thereby maintained. 
     A modification of the configuration shown in  FIG. 11  will be described based on  FIG. 12 . In  FIG. 12 , elements that are the same as those in  FIG. 11  are referred to by the same symbols as in  FIG. 11 , and no description thereof will be given. 
     As shown in  FIG. 12 , the inclination angles of the inside surface of the reducer part  80  with respect to the central axis  29   a  of the other outlet  29  are θ 3  and θ 3 . An inlet center  79   a  of the curved pipe  79  is on the heat exchanger  42  side of the central axis  25   a  of the inlet  25  of the branching member  33 . Setting the inclination angles to θ 3  enables the curved pipe  79  to be rotated about the central axis  25   a  of the inlet  25 . Specifically, the curved pipe  79  can be oriented in any direction. 
     The exhaust heat recovery device  40  of the present invention can be provided to an exhaust pipe that extends from an internal combustion engine to a muffler, or may be provided to an exhaust gas recirculation (EGR) duct for returning a portion of exhaust gas to an internal combustion engine. The exhaust heat recovery device  40  may also be used for other applications. 
     Obviously, various minor changes and modifications of the present invention are possible in light of the above teaching. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.