Patent Publication Number: US-2003230404-A1

Title: Heat exchanger arrangement

Description:
FIELD OF THE INVENTION  
       [0001] The present invention pertains to a heat exchanger arrangement, especially for a vehicle heater, comprising a fluid flow space surrounded by a housing arrangement as well as a temperature sensor arrangement for detecting a variable that is related to the temperature of a fluid flowing through the fluid flow space.  
       BACKGROUND OF THE INVENTION  
       [0002] For operating a heater, as is used, e.g., as a parking heater or auxiliary heater in a motor vehicle, it is important to obtain information on the medium to be heated in order to increase the heat output when the medium temperature is too low and to reduce it when the medium temperature is too high. It is known in this connection that the temperature of the medium is determined in the area in which the thermal energy generated in a heating burner is transferred to the medium. Temperature sensors are introduced for this purpose into a heat exchanger arrangement, and openings or holes, into which the temperature sensors are then inserted with the use of sealing elements, are present for this purpose in housing elements of the heat exchanger arrangement. Besides the problem of ensuring a tight closure, the additional integration of the temperature sensors in such housing elements is an operation that increases the overall costs of such a heat exchanger arrangement and also that of a heater.  
       SUMMARY OF THE INVENTION  
       [0003] The object of the present invention is to provide a heat exchanger arrangement that can be built in a simple manner and at low cost and in which the possibility of detecting the temperature of a fluid flowing through it is created.  
       [0004] This object is accomplished according to the present invention by a heat exchanger arrangement, especially for a vehicle heater, comprising a fluid flow space surrounded by a housing arrangement as well as a temperature sensor arrangement for detecting a variable that is related to the temperature of a fluid flowing through the fluid flow space, wherein the temperature sensor arrangement comprises at least one temperature sensor, which is embedded at least partially into the material of a housing element that forms at least one part of the housing arrangement.  
       [0005] It is essential in the heat exchanger arrangement according to the present invention that at least one temperature sensor is directly embedded into the material of a heat exchanger housing element, so that it is not necessary, on the one hand, to provide an opening which is completely continuous toward the outside and will subsequently accommodate the temperature sensor in the area in which such a temperature sensor is present. Tightness problems can thus be ruled out essentially completely. The integration can also be performed at the same time during the manufacture of this housing element, so that operations to be performed later are not necessary.  
       [0006] Provisions may be made, e.g., for the temperature sensor, of which there is at least one, to be completely surrounded by the material of the housing element. To make it possible to obtain information on the temperature of the fluid flowing through the fluid flow space in certain areas, it is proposed that the temperature sensor, of which there is at least one, have a detection section protruding into the fluid flow space.  
       [0007] In an especially preferred embodiment, the housing element is made of a plastic material, e.g., fiber-reinforced polyamide or polypropylene. Even in the liquid state, such a material has a temperature that is still insufficient to bring about damage to the embedded temperature sensor.  
       [0008] Provisions may be made, e.g., for the housing element to be a pot-shaped heat exchanger housing limiting the fluid flow space on the outside. Furthermore, it is possible for the housing element to be a housing element intended for the integration of a heater. The housing element carrying the at least one temperature sensor embedded in it may be, e.g., a housing element of a vehicle air conditioner or of a vehicle fan, which is already designed such that an additional vehicle heater or a heat exchanger arrangement for such a heater can be inserted at least partially into this housing element, which is already provided or is to be provided on the vehicle.  
       [0009] Furthermore, the present invention pertains to a vehicle heater with a heat exchanger arrangement according to the present invention.  
       [0010] The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011]FIG. 1 is a longitudinal sectional view of a heat exchanger arrangement according to the present invention or of a heater equipped with same; and  
     [0012]FIG. 2 is a vehicle heater system using the heater of FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0013] Referring to the drawing in particular, a heater  10  is shown, which can be used, e.g., as a parking heater or auxiliary heater in a motor vehicle. The heater  10  comprises essentially two areas, namely, a heating burner area  12  and a heat exchanger area  14 . The heating burner  12  area, which is indicated essentially only schematically, comprises, e.g., a combustion air blower, a fuel feed and all the components associated therewith. Furthermore, the heating burner comprises a combustion chamber  18 , which is provided in a partial section of a flame tube  16  and in which a combustion air feed pipe  20  with a plurality of combustion air inlet slots  22  is provided centrally. The combustion air enters the combustion chamber  18  through the air inlet slots  22  and is burned there with the fuel likewise fed into the combustion chamber, e.g., via a porous material. Together with the combustion waste gases, the combustion flame enters the remaining area of the flame tube  16  through a flame diaphragm  24 . The flame tube  16  is open at its axial free end, so that the combustion waste gases meet the heat exchanger  14  there and are deflected and flow back again on the outside of the flame tube  16  and are then released via an outlet, not shown.  
     [0014] It shall be pointed out here that the design of the heating burner and of the components provided for the combustion are shown here only schematically. It is obvious that a great variety of other arrangements may be used here.  
     [0015] The heat exchanger  14  comprises two housing parts, which are inserted one into the other and define a fluid flow space  30  between them. A heat exchanger inner housing  26  defines the space area intended for the flow of the combustion waste gases toward the inside and also forms at the same time the component by which the waste gases leaving the flame tube  16  are axially deflected. The heat exchanger outer housing  28  defines the fluid flow space  30  toward the outside and is tightly connected to the heat exchanger inner housing  26  in an axial end area, namely, the end area located close to the heating burner  12 , for the fluid-tight closure of the fluid flow space  30 . A rib configuration  32  of helical design, which ensures that the fluid flowing through the fluid flow space  30 , e.g., water to be heated or air to be heated, moves through the fluid flow space  30  in a defined manner and can thus absorb the heat transferred by the combustion waste gases to the heat exchanger inner housing  26  in a highly efficient manner, is provided on the outer circumference of the heat exchanger inner housing.  
     [0016] To make it possible to control the operation of the heater  10 , it is advantageous to obtain information on the temperature of the fluid to be heated or also of the fluid already heated. It is known that a temperature sensor arrangement may be provided for this purpose, and a temperature sensor may be arranged, e.g., close to the fluid inlet into the fluid flow space  30 , and the other temperature sensor may be arranged close to the fluid outlet. It is thus possible to determine the extent to which heat has been transferred to the fluid being heated. The heat exchanger  14  shown in the figure also comprises two temperature sensors  36 ,  38 , whose positioning at the heat exchanger  14  is shown as an example only. These two temperature sensors  36 ,  38  could, of course, be positioned in other areas as well. It is significant that according to the principles of the present invention, the temperature sensors  36 ,  38  are embedded at least partially into the material forming the heat exchanger outer housing  28 . The temperature sensor  36  is completely surrounded by the material of the heat exchanger outer housing  28 . Only the electric contacting line  44  leads through the material of the heat exchanger outer housing  28  to the outside. The temperature sensor  36  is otherwise completely encapsulated by the material of the heat exchanger outer housing  28 . It is recognized above all that no opening, through which leakage could occur, is present on the surface of the heat exchanger outer housing  28  defining the fluid flow space  30  in the area of the temperature sensor  36 .  
     [0017] The temperature sensor  38  is designed such that it projects from the heat exchanger outer housing  28  and protrudes into the fluid flow space  30  with its temperature detection section  40 . It is thus possible to detect, e.g., the fluid temperature close to the surface of the heat exchanger inner housing  26  with this temperature sensor  38  or optionally to detect the temperature of the heat exchanger inner housing  26  by directly contacting the surface of the heat exchanger inner housing  26  and thus to provide information for a possible recognition of overheating. However, a tight closure of the heat exchanger outer housing  28  is otherwise provided in the area of the temperature sensor  38 . Only the electric contacting line  42  is led out of the material of the heat exchanger outer housing  28  to the outside here as well.  
     [0018] The essential advantage of the design according to the present invention, in which temperature sensors  36 ,  38  of the temperature sensor arrangement  34  are embedded at least partially directly into the material of the heat exchanger outer housing  28 , i.e., they are also sealed in by this material during the manufacture, is that no additional operations need to be carried out to prepare openings for sensors and no operations are likewise necessary for the subsequent mounting of temperature sensors. Furthermore, fluid leakage problems can be ruled out practically completely. It proved to be advantageous for the heat exchanger outer housing to be made of a plastic material, e.g., fiber-reinforced polyamide or polypropylene. An essential advantage is in this connection that this material is in a liquid state at comparatively low temperatures, so that a temperature-induced damage to the temperature sensors  36 ,  38  can be ruled out during the manufacture of the heat exchanger outer housing  28 , during which the temperature sensors  38 ,  36  are also sealed in the heat exchanger outer housing at the same time.  
     [0019] It is apparent that the embedding of the temperature sensors in a housing part of the heat exchanger can also be achieved if, e.g., a housing already present in a vehicle shall be used for this purpose, so that the heater shall be integrated within an already existing housing, e.g., of a vehicle fan or a vehicle air conditioner.  
     [0020] The heater  10  may be a part of a vehicle heater system as shown in FIG. 2. The vehicle internal combustion engine (I.C.E.)  46  may be connected to the vehicle heat exchanger  14  via fluid lines  52  and a pump  48 . The vehicle heat exchanger  50  may be connected by these lines to the heat exchanger  14  of the heater  10 . Other system configurations can be provided including bypass lines to bypass the I.C.E.  46  or to bypass the heat exchanger  50 . The direction of fluid flow in FIG. 2 may be reversed and arrangements other than the circuit line  52  may be employed. Further embodiments of the system may utilize the heater  10  with total independence from the vehicle I.C.E.  46 . The temperature sensor arrangement  34  may be connected to a control element  60  with temperature sensor  36  connected to control element  60  by line  44  and temperature sensor  38  connected to control element  60  by line  42 . The burner control element  60  is connected to controllable aspects of the burner  12  such as a fuel feed, air intake, etc..  
     [0021] While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.