Patent Publication Number: US-7896308-B2

Title: Mounting structure and method for heat accumulation tank

Description:
INCORPORATION BY REFERENCE 
     The disclosure of Japanese Patent Application No. 2003-093015 filed on Mar. 31, 2003, including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a mounting structure and method for mounting a heat accumulation tank to receiving member. 
     2. Description of the Related Art 
     JP-A-2002-188442 and JP-A-2000-73764 disclose proposals for a heat accumulation tank. This heat accumulation tank includes a tank main body which stores, while keeping warm, coolant for an internal combustion engine. The tank main body has an inner tank and an outer tank, with a space therebetween which is substantially a vacuum in order to improve heat retention. Also as related art, JP-A-10-86644 discloses a mounting structure for mounting a heat accumulation tank to a receiving member (such as a vehicle body member). More specifically, the publication discloses a mounting structure that fixedly supports a tank main body using a bracket that is attached to a receiving member. 
     However, the holding strength of the mounting structure for a heat accumulation tank described in JP-A-10-86644 is weak because only a portion of the heat accumulation tank is held in the circumferential direction. Further, it is difficult to apply the surface pressure evenly because the tank main body is directly supported by the bracket. This results in problems, such as that it makes the tank main body susceptible to damage. Also, if the bracket, which should reliably hold the tank main body, is spot welded to the outer tank of the tank main body, a slow leak may develop across the interface of the spot weld over an extended period of time. This slow leak reduces the degree of vacuum between the inner and outer tanks, which may result in a decrease in heat retaining performance. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing problems, one aspect of this invention relates to a mounting structure for a heat accumulation tank described below. This mounting structure includes i) a tank main body which constitutes a heat accumulation tank, ii) an elastic member which wraps around substantially the entire periphery of the tank main body, and iii) a mounting member which wraps around substantially the entire periphery of an outer peripheral surface of the elastic member and which is attached to a receiving member. 
     Further, another aspect of the invention relates to a mounting method for a heat accumulation tank. This mounting method includes the steps of i) wrapping an elastic member around substantially the entire periphery of a tank main body, which constitutes a heat accumulation tank, and ii) wrapping a mounting member around substantially the entire periphery of an outer peripheral surface of the elastic member and attaching the mounting member to a receiving member. 
     According to the mounting structure and mounting method for a heat accumulation tank described above, the heat accumulation tank is able to be reliably held by the mounting member because the mounting member holds the tank main body around its entire periphery. Further, because the tank main body is held by the mounting member via the elastic member, the surface pressure is able to be applied evenly. Also, because the elastic member is provided between the mounting member and the tank main body, and the mounting member is not welded to the tank main body, a slow leak will not develop at the interface of the weld zone. As a result, the degree of vacuum in the space between the inner tank and outer tank can be maintained, thus enabling heat retention to be achieved over an extended period of time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned embodiment and other embodiments, objects, features, advantages, technical and industrial significance of this invention will be better understood by reading the following detailed description of the preferred embodiments of the invention, when considered in connection with the accompanying drawings, in which: 
         FIG. 1  is a full front view of a mounting structure of a heat accumulation tank and the heat accumulation tank according to one exemplary embodiment of this invention; 
         FIG. 2  is a front view of the mounting structure shown in  FIG. 1 ; 
         FIG. 3  is a bottom view of the mounting structure shown in  FIG. 1 ; 
         FIG. 4  is a schematic plan view of a tank main body and the mounting structure shown in  FIG. 1 ; 
         FIG. 5  is a schematic side view of a band shown in  FIG. 1 ; 
         FIG. 6  is a front view of the mounting structure shown in  FIG. 1 ; 
         FIG. 7  is a front view of the mounting structure shown in  FIG. 6  with a shift inhibiting portion; 
         FIG. 8  is a front view of the tank main body in  FIG. 1 , in which the outer diameter increases in the upward direction, and the mounting structure; and 
         FIG. 9  is an overall sectional view of the heat accumulation tank to which the mounting structure according to the exemplary embodiment of the invention is applied. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     In the following description and the accompanying drawings, the present invention will be described in more detail in terms of exemplary embodiments. 
     A heat accumulation tank  1  to which a mounting structure for a heat accumulation tank according to one exemplary embodiment of the invention can be applied will be described with reference to  FIGS. 1 and 9 . 
     As shown in  FIGS. 1 and 9 , the heat accumulation tank  1  has a tank main body  10  which stores fluid (coolant) while keeping it warm. The heat accumulation tank  1  also has a housing  20  in which is provided a fluid passage that opens into an inner portion of the tank main body  10 , and through which fluid flows. The tank main body  10  has a tank main body opening  13  into which the housing  20  is inserted. The heat accumulation tank  1  has an axial core, and is mounted to a receiving member of a vehicle with an orientation such that the axial core is substantially vertically. In the example shown in the drawing, the heat accumulation tank  1  is mounted to the receiving member with the tank main body opening  13  facing downward. The invention, however, is not limited to this. For example, the heat accumulation tank  1  may alternatively be mounted to the receiving member with the tank main body opening  12  facing upward. 
     As shown in  FIG. 9 , the tank main body  10  is provided with an inner tank  11  and an outer tank  12 . The inner tank  11  and outer tank  12  is made out of stainless steel, for example. The inner tank  11  and outer tank  12  are welded together at the lower end of the tank main body opening  13  (this weld zone where the inner tank  11  and outer tank  12  are welded together is denoted by the reference numeral  15 ). A sealed space  14  is formed between the inner tank  11  and the outer tank  12 . This sealed space  14  is substantially a vacuum. Because of the insulation effect of this vacuum, the sealed space  14  keeps the warm coolant, which flows into the tank main body  10 , warm. When this heat accumulation tank  1  is used in a cooling system of an internal combustion engine (i.e., engine), warm coolant flows through the fluid passage provided in the housing  20  and into the inner tank  11 , where it is stored and kept warm. The stored coolant then flows out from the heat accumulation tank during, for example, preheating before staring the engine. 
     A rectifying member  16  (also referred to as a “mixture prevention plate”) is provided in the inner tank  11 . This rectifying member  16  serves to uniformly rectify the flow of cold coolant that flows in during, for example, preheating before starting the engine. The rectified coolant is gradually discharged above the rectifying member and slowly rises. Therefore, the warm coolant above the rectifying member is inhibited from mixing with the cold coolant below all at once. A single pipe insertion hole  17  and a plurality of holes through which the coolant passes after it is uniformly rectified are provide in the rectifying member  16 . 
     The housing  20  is inserted in the inner periphery side of the tank main body opening  13 . The area between the tank main body opening  13  and the housing  20  is sealed by a seal (i.e., an O-ring) to prevent leakage. The housing  20  has a portion that is located on the outer portion of the tank main body  10 . A temperature sensor  23  and a drain plug  24  are attached to this portion of the housing  20 . The housing  20  is made of resin, for example. The weld zone  15  of the inner tank  11  and outer tank  12  at the tank main body opening  13  of the tank main body  10  is not enclosed from the outside by the housing  20  in the radial direction of the tank main body opening  13 , but instead is open to the outside in that direction. 
     A pipe  25  is inserted into and fixed to the housing  20 . One end of the pipe  25  is connected to the fluid passage of the housing  20 . The other end of the pipe  25  opens to a space full of coolant inside the inner tank  11 . The pipe  25  extends through the pipe insertion hole  17  in the rectifying member  16 . Midway in the pipe  25  is provided a flange  26  that extends in the radial direction of the pipe  25 . The flange  26  and a peripheral portion  18  of the pipe insertion hole  17  in the rectifying member  16  are not fixed to each other. 
     Next, the mounting structure of the heat accumulation tank  1  according to this exemplary embodiment of the invention will be described with reference to  FIGS. 1 to 8 . As shown in  FIGS. 1 to 4 , the heat accumulation tank  1  with the tank main body  10  is mounted to, and supported by, a receiving member (such as a vehicle body member) via a heat accumulation tank mounting member  30 . This heat accumulation tank mounting member  30  is, for example, made of metal. Also, a housing support member  40  for holding the housing  20  to the tank main body  10  is attached to the heat accumulation tank mounting member  30 . 
     As shown in  FIG. 4 , the heat accumulation tank  1  is mounted to, and supported by, the receiving member via an elastic member  39  which wraps around the tank main body  10 . This elastic member  39  wraps around substantially the entire tank main body  10 . The heat accumulation tank mounting member  30  wraps around the outer peripheral surface of the elastic member  39 , around substantially the entire periphery of the tank main body  10 . Also, by being squeezed in the circumferential direction, the heat accumulation tank mounting member  30  presses the tank main body  10  to the inside in the radial direction via the elastic member  39 . In this way, the heat accumulation tank mounting member  30  is mounted to the receiving member while the tank main body  10  is held via the elastic member  39 . 
     The elastic member  39  that wraps around the tank main body  10  is a band-shaped member having elasticity. The material of this member is, for example, rubber. The elastic member  39  may be separate from the heat accumulation tank mounting member  30 . Alternatively, the elastic member  39  may be attached to the heat accumulation tank mounting member  30  with an adhesive, or may be vulcanize-bonded to the heat accumulation tank mounting member  30 . The example in the drawing shows a case in which the elastic member  39  is separate from the heat accumulation tank mounting member  30 . When the elastic member  39  is attached or vulcanize-bonded to the heat accumulation tank mounting member  30 , slippage between the elastic member  39  and the heat accumulation tank mounting member  30  is minimized. As a result, the tank holding reliability improves. 
     The heat accumulation tank mounting member  30  has a band (i.e., a band-shaped bracket)  31 . The heat accumulation tank mounting member  30  also has a bracket  32 . The band  31  extends around substantially the entire periphery of the tank main body  10  in the circumferential direction of the tank main body  10 , and is cut in one location on its periphery. Flanges  311  and  312  are formed on both ends of the band, as shown in  FIG. 3  for example. The tank main body  10  is pressed inward in the radial direction via the elastic member  39  by tightening a bolt  33  that secures flanges  311  and  312  together. 
     Referring to  FIG. 2 , the bracket  32  is attached to the band  31  by, for example, spot welding (the spot weld zones are denoted by reference numeral  35  in the drawing) in at least one location on the periphery of the band  31 . The band  31  is not welded directly to the tank main body  10 , but rather holds the tank main body  10  via the elastic member  39 . The bracket  32  attached to the band  31  is supported via a rubber bushing  55  on a vehicle side bracket. The tank main body  10  is then mounted to, and supported by, the receiving member by attaching the vehicle side bracket with a bolt or the like to the receiving member. 
     Referring to  FIG. 1 , a housing support member  40  includes a upright bracket  41  and bolts  42  and  43 . One end of the upright bracket  41  is attached to the band  31  by the bolt  43  at a plurality of locations (e.g., four places) in the circumferential direction of the band. The other end of the upright bracket  41  is fixed to the housing  20  by the bolt  42  or the like. As a result, the housing  20  is held to the tank main body  10  by the upright bracket  41 . 
     Operation of the mounting structure for the heat accumulation tank according to the exemplary embodiment of the invention will now be described. 
     The heat accumulation tank mounting member  30  covers substantially the entire periphery of the outer tank  12  of the tank main body  10 , holding the tank main body  10  around its entire circumference. Accordingly, the tank main body  10  is held with a strong holding force. 
     Further, because the heat accumulation tank mounting member  30  holds the tank main body  10  via the elastic member  39 , the surface pressure on the tank main body  10  is able to be applied evenly. That is, the surface pressure on the tank main body  10  is not greater in one area than another. As a result, distortion of the tank main body  10  and slow leaks, which occur from such distortion, are able to be minimized, making it possible for the tank main body  10  to be held with high reliability. 
     Also, providing the elastic member  39  provided between the heat accumulation tank mounting member  30  and the tank main body  10  obviates the need for welding the heat accumulation tank mounting member  30  to the tank main body  10 . Therefore, the degree of vacuum in the space between the inner tank and outer tank can be maintained without a slow leak, which can occur at the interface of the weld zone, occurring. As a result, the heat accumulation tank  1  can be held reliably over an extended period of time. 
     One example of the mounting structure for the heat accumulation tank and the operation of that mounting structure is as follows. 
     The elastic member  39  is preferably a molded part. If the elastic member  39  is made by extrusion molding, the surface becomes too smooth. As a result, the friction coefficient to hold the tank main body  10  is reduced, resulting in a tendency for the tank main body  10  to slip against the elastic member  39  and fall. If the elastic member  39  is a molded part, however, the friction coefficient of the surface of the elastic member  39  can be made high so that the tank main body  10  is less apt to slip against the elastic member  39  and fall. As a result, when the heat accumulation tank mounting member  30  is attached to the outer peripheral surface of the elastic member  39  and tightened, the tank main body  10  can be reliably held by the heat accumulation tank mounting member  30 . 
     The length of the elastic member  39  (i.e., the length in the circumferential direction of the tank main body  10 ) is made slightly shorter than the length of the circumference of the outer peripheral surface of the outer tank  12  of the tank main body  10 . As a result, the end portions of the elastic member  39  do not overlap when the elastic member  39  is wrapped around the outer peripheral surface of the outer tank  12 . If the end portions of the elastic member  39  overlap, the holding force that holds the tank main body  10  from the periphery becomes uneven, distorting at the overlapping portions of the end portions of the elastic member  39 . As a result, the tank main body  10  may no longer able to be reliably held and the tank main body  10  may deform from being pressed unevenly. If the length of the elastic member  39  is set as described above, however, these problems will not occur. 
     When attaching the bracket  32  to the band  31  by spot welding, it is desirable that the spot weld zone  35  not be at a portion  36  where major surface pressure is generated (hereinafter also referred to as “major surface pressure receiving portion”). If tightening force acts on the band  31  in the circumferential direction, a large surface pressure will be generated at the middle portion when the band  31  is divided into thirds in the width direction. That is, the major surface pressure receiving portion  36  is the middle potion of the band  31  when the band  31  is divided into thirds internal combustion engine the width direction, as shown in  FIG. 5 . Irregularities and portions where the friction coefficient is discontinuous, which occur at the spot weld zone  35 , are undesirable at that portion  36  because they result in uneven surface pressure over the entire area of the band  31 . Therefore, the spot weld zone  35  is preferably positioned on a portion other than the major surface pressure receiving portion  36  of the band  31 . That is, the spot weld zone  35  is preferably provided on at least one side portion from among both side portions of the band when the band is divided into thirds in the width direction. According to this structure, it is possible to prevent the surface pressure at the major surface pressure receiving portion  36  from becoming uneven, which enables the heat accumulation tank  1  to be held with greater reliability. 
     If the width of the band  31  is too narrow, thus making it difficult to position the spot weld zones  35  on a portion other than the major surface pressure receiving portion  36 , the width of the band  31  at the mounting portion of the bracket  32  may be made wider than the band width at the other portions (this wide portion is denoted by reference number  37  in the drawing), as shown in  FIGS. 2 and 6 . Providing this wide portion  37  facilitates positioning the spot weld zones  35  on a portion other than the major surface pressure receiving portion  36 . 
     The inner portion of the tank main body  10  is sealed from the outer portion by the seal  19  provided between the tank main body opening  13  and the housing  20 . Hydraulic pressure and force in the axial direction due to the weight of the fluid acts on the tank main body  10 . If that force is greater than the frictional force of the seal  19 , the following occurs. That is, when the holding force that holds the tank main body  10  of the heat accumulation tank mounting member  30  weakens, the tank main body  10  starts to move in the axial direction relative to the housing  20 . The force in the axial direction from the hydraulic pressure acts on the tank main body  10  in an upward direction, trying to lift up the tank main body  10  with respect to the housing  20 . Further, the force in the axial direction from the weight of the fluid acts on the tank main body  10  in a downward direction, trying to force the tank main body  10  down. 
     In order to minimize this kind of movement of the tank main body  10  with respect to the housing  20 , it is desirable to provide a shift inhibiting portion  34  on the heat accumulation tank mounting member  30 , as shown in  FIG. 7 . This shift inhibiting portion  34  inhibits the tank main body  10  from shifting upward with respect to the housing  20 . 
     As shown in  FIG. 7 , in the structure in which the heat accumulation tank mounting member  30  includes the shift inhibiting portion  34 , even when the bracket that forms the shift inhibiting portion  34  is formed separately from the band  31  and attached to the band  31  by spot welding, it is still desirable to position the spot weld zone on a portion other than the major surface pressure receiving portion  36 . If the width of the band  31  is too narrow, thus making it difficult to position the spot weld zones  35  on a portion other than the major surface pressure receiving portion  36 , the width of the band  31  at the bracket mounting portion that forms the shift inhibiting portion  34  may be made wider than the band width at the other portions (this wide portion is denoted by reference number  37  in the drawing). As a result, it is possible to position the spot weld zones  35  on a portion other than the major surface pressure receiving portion  36  of the band  31 . 
     When the upright bracket  41  of the housing support member  40  is fixed to the band  31  by the bolt  42 , it is desirable to provide an extended portion  38  that extends in the axial direction of the tank main body  10  on the band  31  and fix the upright bracket  41  to the band  31  at the extended portion  38 . For example, a portion mid-way in the extended portion  38  may be bent away from the tank main body  10  in the radial direction, and the upright bracket  41  may be fixed to the extended portion  38  of the band  31  at the portion away from the tank main body  10 , as shown in  FIG. 2 . In this way, providing the extended portion  38  facilitates positioning the mounting portion of the upright bracket  41  on a portion other than the major surface pressure receiving portion  36  of the band  31 . 
     Even if the bracket which forms the bracket  32  and the shift inhibiting portion  34  is attached to the band  31 , providing the extended portion on the band  31  makes it easier to position the bracket mounting portion on a portion other than the major surface pressure receiving portion  36  of the band  31 . 
     The tank main body  10  has an axial core (which is the same axial core as that of the heat accumulation tank  1 ). The heat accumulation tank  1  is mounted to the receiving member with the axial core of the tank main body  10  pointing up and down. In this case, it is desirable that the tank main body  10  have a shape in which its the diameter increases in the upward direction, as shown in  FIG. 8 . With this kind of structure, the tightening load when the tank main body  10  slides down, due to its weight, against the heat accumulation tank mounting member  30  increases by the wedge effect. As a result, it is possible to reliably prevent the tank main body  10  from falling off of the heat accumulation tank mounting member  30 . 
     While the invention has been described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the exemplary embodiments or constructions. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the exemplary embodiments are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the invention.