Patent Publication Number: US-2023155311-A1

Title: Evaluation jig and evaluation method

Description:
This nonprovisional application is a continuation application of U.S. application Ser. No. 17/117,293 filed Dec. 10, 2020, claiming priority of Japanese Patent Application No. 2020-003140 filed on Jan. 10, 2020 with the Japan Patent Office. The entire contents of each application are hereby incorporated by reference. 
    
    
     BACKGROUND 
     Field 
     The present disclosure relates to an evaluation jig and an evaluation method. 
     Description of the Background Art 
     A connecting portion of a charging connector on the side of facilities and a charging inlet on the side of a vehicle generates heat due to contact resistance when a current passes therethrough. This is particularly remarkable when rapid charging is performed with a large current (for example of 400 A). Accordingly, a liquid-cooled type charging connector coolable with liquid such as water is known. For example, Japanese Patent Laying-Open No. 2019-187035 discloses a liquid-cooled type charging connector comprising a connector connectable to a vehicular inlet and a cooling mechanism capable of cooling the connector with a coolant (or cooling water). 
     SUMMARY 
     When such a charging connector as disclosed in Japanese Patent Laying-Open No. 2019-187035 varies in coolability, it affects a period of time taken to charge power. For example, a charging connector with relatively low coolability requires a longer charging time. Therefore, there is a need for appropriately evaluating a charging connector in coolability. 
     An object of the present disclosure is to provide an evaluation jig and an evaluation method capable of appropriately evaluating a charging connector in coolability. 
     In order to address the above issue, an evaluation jig comprising a pair of female terminals connectable to a pair of male terminals of a charging connector may be used to evaluate the charging connector in coolability (or a degree at which temperature increases at a connecting portion of the male terminal and the female terminal). 
     If the contact resistance between the male terminal and the female terminal when an evaluation is made varies whenever the evaluation is made, the evaluation provides an unreliable result. Accordingly, it is preferable that the contact resistance of the male terminal and the female terminal of the evaluation jig be adjustable to fall within a prescribed range. 
     According to one aspect of the present disclosure, an evaluation jig comprises a pair of female terminals connectable to a pair of male terminals of a charging connector and an adjustment member that can adjust contact resistance of the female terminal and the male terminal, the female terminal being reducible in diameter, the adjustment member being capable of applying an external force to the female terminal to reduce the female terminal in diameter. 
     In the present evaluation jig, the female terminal is reducible in diameter and the adjustment member can apply an external force to the female terminal to reduce the female terminal in diameter, and contact resistance of the male terminal and the female terminal can be adjusted to fall within a prescribed range. Thus, the charging connector&#39;s coolability can be appropriately evaluated. 
     It should be noted, however, that, around the male terminal of the charging connector, there exists a tubular wall surrounding the male terminal, and in the case of a structure in which the adjustment member applies external force to the female terminal, as described above, the adjustment member may interfere with the tubular wall. 
     According to one aspect of the present disclosure, an evaluation method is an evaluation method for evaluating a charging connector in coolability by connecting an evaluation jig to the charging connector, the charging connector including a pair of male terminals coolable with a coolant and a pair of tubular walls surrounding each of the paired male terminals, the evaluation jig including a pair of female terminals connectable to the pair of male terminals and reducible in diameter and an adjustment member capable of applying an external force to each of the paired female terminals to reduce the female terminal in diameter, the pair of female terminals being connected to the pair of male terminals in evaluating the charging connector in coolability, the method comprising: partially removing each tubular wall of the paired tubular walls to form around the male terminal an operating space allowing an operation to be performed therein via the adjustment member to adjust the external force; connecting the pair of female terminals to the pair of male terminals; and adjusting the external force in the operating space by the adjustment member so that contact resistance between the male terminal and the female terminal falls within a prescribed range. 
     In the present evaluation method, an operating space allowing an operation to be performed therein to adjust external force is formed around the male terminal, and contact resistance can be adjusted in a state with the evaluation jig having the female terminal connected to the male terminal. 
     Furthermore, in the step of removing, the tubular wall preferably has removed a portion other than a portion at which the paired tubular walls face each other. 
     This suppresses short circuit of the male terminals. 
     Furthermore, the adjustment member includes an annular band that is attached to an outer peripheral surface of the female terminal and formed in an annular shape surrounding the female terminal, a metal band that is attached to an outer peripheral surface of the annular band and can apply a force to the female terminal to reduce the female terminal in diameter, and an adjustment unit that can adjust a force applied by the metal band to clamp the female terminal, and the annular band may be made of an electrically and thermally insulating material. In this case, preferably, in the step of connecting, the pair of female terminals is connected to the pair of male terminals in a state with the annular band and the metal band attached to each female terminal, and in the step of adjusting, the force applied by the metal band to clamp the female terminal is adjusted in the operating space. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagram schematically showing a vehicle charged. 
         FIG.  2    is a front view of a male connector. 
         FIG.  3    is a cross section taken along a line indicated in  FIG.  2   . 
         FIG.  4    is a perspective view of an evaluation jig according to an embodiment of the present disclosure. 
         FIG.  5    is a perspective view in a vicinity of a female terminal of the evaluation jig. 
         FIG.  6    is a perspective view showing a relationship between the female terminal of the evaluation jig and an adjustment member. 
         FIG.  7    is a plan view of the female terminal of the evaluation jig. 
         FIG.  8    is a perspective view of the female terminal shown in  FIG.  7   . 
         FIG.  9    is a perspective view of the female terminal at an angle different from that of  FIG.  8   . 
         FIG.  10    is an enlarged perspective view of a distal end portion of the female terminal. 
         FIG.  11    is a cross section taken along a line XI-XI shown in  FIG.  7   . 
         FIG.  12    is a cross section taken along a line XII-XII shown in  FIG.  7   . 
         FIG.  13    is an enlarged view of a range indicated by a solid line XIII shown in  FIG.  12   . 
         FIG.  14    is a front view of a male connector having a tubular wall partially removed. 
         FIG.  15    is a perspective view of the male connector shown in  FIG.  14   . 
         FIG.  16    is a cross section taken along a line XVI-XVI indicated in  FIG.  14   . 
         FIG.  17    is a perspective view showing a state in which the evaluation jig has a female terminal connected to a male terminal of the male connector shown in  FIG.  15   . 
         FIG.  18    is a cross section of the diagram shown in  FIG.  17   . 
         FIG.  19    is a diagram schematically showing a degree at which temperature rises at each portion around a connecting portion of a male terminal and a female terminal. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An Embodiment of the present disclosure will be described with reference to the drawings. In the drawings referred to below, identical or equivalent members are identically denoted. 
       FIG.  1    is a diagram schematically showing a vehicle charged. More specifically,  FIG.  1    shows a state in which a charging connector  5  connected to a facility  7  such as a charging stand via a facility-side electric wire  6  is connected to a charging inlet  2  of a vehicle  1 . Vehicle  1  is, for example, an electric vehicle. 
     Charging connector  5  includes a handle (not shown) held by a user, and a male connector  10  (see  FIG.  2   ) connected to the handle. Charging connector  5  is cooled by a coolant. That is, charging connector  5  is a so-called liquid-cooled charging connector. An example of the coolant includes cooling water. The coolant flows between facility  7  and charging connector  5  via facility-side electric wire  6 . 
     Male connector  10  is a portion connected to charging inlet  2  of vehicle  1 . In the present embodiment, male connector  10  is based on the ChaoJi standard. As shown in  FIG.  2   , male connector  10  includes a pair of male terminals  11 , a protective grounding terminal  12 , a pair of charging connection confirmation terminals  13 , a pair of charging communication terminals  14 , and a male casing  15 . 
     Each male terminal  11  is formed in a round column. Each male terminal  11  is a direct-current power supply terminal. One male terminal  11  is a positive electrode and the other male terminal  11  is a negative electrode. In the present embodiment, male terminal  11  has an outer diameter of 9 mm. 
     Protective grounding terminal  12  is disposed at a position spaced from a center portion between the paired male terminals  11  on one side in a direction orthogonal to both an imaginary line connecting the paired male terminals  11  (i.e., a lateral direction in  FIG.  2   ) and an axis of each male terminals  11 , that is, in a vertical direction in  FIG.  2   . 
     Each charging connection confirmation terminal  13  is disposed at a position spaced from one male terminal  11  on one side in the orthogonal direction. 
     Each charging communication terminal  14  is disposed at a position spaced from the other male terminal  11  on one side in the orthogonal direction and also spaced from each charging connection confirmation terminal  13  in a direction parallel to the imaginary line connecting the paired male terminals  11 . 
     Male casing  15  holds terminals  11  to  14 . Male casing  15  is made of resin. Male casing  15  has a bottom wall  16  and a tubular wall  17 . 
     As shown in  FIG.  3   , bottom wall  16  holds terminals  11  to  14  in a state in which terminals  11  to  14  are inserted therethrough. Bottom wall  16  is formed in a flat plate.  FIG.  3    shows a part of female connector  20  of charging inlet  2 . 
     Tubular wall  17  surrounds male terminal  11 . Tubular wall  17  erects from a portion of bottom wall  16  around male terminal  11 . Tubular wall  17  has a cylindrical inner peripheral surface. Female connector  20  of charging inlet  2  is inserted into a space between the inner peripheral surface and an outer peripheral surface of male terminal  11 . As shown in  FIG.  3   , tubular wall  17  has an inner diameter set to 23 mm. 
     Charging inlet  2  is provided on an external surface of vehicle  1 . Charging inlet  2  includes female connector  20 . Female connector  20  has a pair of female terminals  21  and a female casing  25 . 
     Each female terminal  21  is connectable to male terminal  11 . As shown in  FIG.  3   , each female terminal  21  has a shape capable of receiving male terminal  11 . 
     Female casing  25  holds female terminals  21 . Female casing  25  is made of resin. As shown in  FIG.  3   , female casing  25  has a facing portion  26  and a tubular portion  27 . 
     Facing portion  26  is a portion facing tubular wall  17  in a direction parallel to the axial direction of male terminal  11  (i.e., a vertical direction in  FIG.  3   ). Facing portion  26  has a surface  26 S formed flat. As shown in  FIG.  3   , a distance between surface  26 S of facing portion  26  and a surface  16 S of bottom wall  16  in the direction parallel to the axial direction of male terminal  11  is set to 40 mm. 
     Tubular portion  27  is formed to have a cylindrical shape surrounding female terminal  21 . Tubular portion  27  is connected to facing portion  26  in a posture such that tubular portion  27  has its center axis orthogonal to facing portion  26 . Tubular portion  27  has an outer diameter smaller than the inner diameter of tubular wall  17 . In a state with charging connector  5  connected to charging inlet  2 , tubular portion  27  has a distal end portion  27   a  in contact with surface  16 S of bottom wall  16 . As shown in  FIG.  3   , distal end portion  27   a  has a length set to 6 mm in a direction parallel to the axial direction of tubular portion  27 . 
     Hereinafter, evaluation jig  50  will be described with reference to  FIGS.  4  to  13   . Evaluation jig  50  is a jig capable of evaluating charging connector  5  in coolability (or amount of heat generated at a connecting portion of male terminal  11  and the female terminal). As shown in  FIG.  4   , evaluation jig  50  includes a pair of female terminals  100 , an electric wire  200 , a pair of crimp terminals  300 , and a pair of adjustment members  400 . 
     Each female terminal  100  is a terminal connected to male terminal  11 . Each female terminal  100  includes a plurality of (eight in the present embodiment) contact pieces  110 , a support portion  120 , and a female-side flange  130 . 
     Each contact piece  110  is a portion that can contact male terminal  11 . The plurality of contact pieces  110  are disposed about and spaced from a center axis A (see  FIGS.  11  to  13   ). Specifically, the plurality of contact pieces  110  are disposed about and equally spaced from center axis A. Contact pieces  110  are preferably set in number to 3 or more and 8 or less, particularly preferably 8. Each contact piece  110  has a flexible piece  112  and a contact portion  114 . 
     Flexible piece  112  has a shape extending in a direction parallel to center axis A. Flexible piece  112  forms a portion of a cylinder having center axis A. In other words, in the cross sections shown in  FIGS.  12  and  13   , flexible piece  112  has an outer peripheral surface in the form of an arc. A slit  112 S is provided between any pair of flexible pieces  112  adjacent in the circumferential direction of the cylinder. 
     In the direction parallel to center axis A, flexible piece  112  has a length L 1  (see  FIG.  7   ) set to be equal to or larger than twice the outer diameter of the cylinder. In the present embodiment, the cylinder has an outer diameter φ 2  (see  FIG.  11   ) of 17 mm, and flexible piece  112  has length L 1  of 35 mm. The cylinder has an inner diameter φ 1  (see  FIG.  11   ) of 13 mm. That is, flexible piece  112  has a thickness of 2 mm. 
     Flexible piece  112  is elastically deformable such that flexible piece  112  has a distal end portion  112   a  displaced in the radial direction of the cylinder relative to a proximal end portion of flexible piece  112 , which is a connecting portion of flexible piece  112  and support portion  120 . That is, the plurality of contact pieces  110  (the cylinder) can be reduced in diameter. 
     As shown in  FIGS.  12  and  13   , flexible piece  112  has a facing surface  112   b  facing flexible piece  112  adjacent to flexible piece  112  of interest in the circumferential direction of the cylinder. Any pair of facing surfaces  112   b  facing each other in the circumferential direction are parallel to each other. The paired facing surfaces  112   b  are spaced by 1 mm. 
     Contact portion  114  has a shape protruding from the inner surface of flexible piece  112  toward center axis A. Contact portion  114  is connected to the inner surface of flexible piece  112  at a portion away from distal end portion  112   a  in the direction parallel to center axis A. That is, distal end portion  112   a  of flexible piece  112  configures a protruding portion protruding from contact portion  114  in the direction parallel to center axis A away from support portion  120  (or downward in  FIG.  11   ). Contact portion  114  has a shape curved so as to protrude inward in the radial direction. As shown in  FIG.  13   , flexible piece  112  and contact portion  114  have a boundary portion  113  therebetween in a curve. Contact portion  114  has an apex  114   c  with a curvature smaller than that of boundary portion  113 . In the present embodiment, apex  114   c  has a radius of curvature of 1 mm. Boundary portion  113  has a radius of curvature for example of 0.5 mm. 
     As shown in  FIG.  13   , a straight line connecting a specific apex  114   c  and center axis A and a straight line connecting an apex  114   c  adjacent to the specific apex  114   c  and center axis A form an angle of 45 degrees. A tangent to an end on one side of contact portion  114  in the circumferential direction and a tangent to an end on the other side of contact portion  114  in the circumferential direction form an angle of 30 degrees. 
     Contact portion  114  has a shape extending in the direction parallel to center axis A. As shown in  FIGS.  10  and  11   , contact portion  114  has a contact edge portion  114   a  and a connecting portion  114   b.    
     Contact portion  114  has a shape extending in the direction parallel to center axis A. Contact edge portion  114   a  has a length L 3  of 4.7 mm. 
     Connecting portion  114   b  connects contact edge portion  114   a  and an inner surface of flexible piece  112 . Connecting portion  114   b  has a shape inclined so as to gradually approach the inner surface of flexible piece  112  as connecting portion  114   b  is farther away from contact edge portion  114   a  in the direction parallel to center axis A. Connecting portion  114   b  and the inner surface of flexible piece  112  have a boundary portion therebetween with a radius of curvature of 0.5 mm. Connecting portion  114   b  and contact edge portion  114   a  have a boundary portion therebetween with a radius of curvature of 1.5 mm. 
     Support portion  120  supports the plurality of contact pieces  110 . In the present embodiment, support portion  120  is formed to have a cylindrical shape having center axis A as a center. Support portion  120  has an outer peripheral surface contiguous to that of each flexible piece  112 . That is, support portion  120  has an outer diameter equal to that of the cylinder composed of the plurality of flexible pieces  112 . 
     As shown in  FIG.  11   , support portion  120  is equal in thickness to each flexible piece  112 . As shown in  FIG.  7   , in a direction along center axis A, support portion  120  has a length L 2  set to be smaller than length L 1  of each flexible piece  112 . Specifically, support portion  120  has length L 2  of 22 mm. Support portion  120  may be formed in a round columnar shape, a rectangular columnar shape, or the like. 
     Female-side flange  130  has a shape projecting from an outer peripheral surface of support portion  120  outward in the radial direction of support portion  120 . Female-side flange  130  is formed flat. In the direction parallel to center axis A, female-side flange  130  has a length equal to that of support portion  120  (22 mm in the present embodiment). 
     Female-side flange  130  is provided with an insertion hole  130   h . Insertion hole  130   h  has a diameter of 10.5 mm. A distance between center axis A and the center of insertion hole  130   h  is 21 mm. 
     Electric wire  200  is provided to connect the paired female terminals  100  to each other. Electric wire  200  is made of copper or silver. Electric wire  200  preferably has a cross-sectional area set to 70 mm 2  or more and 95 mm 2  or less. In the present embodiment, electric wire  200  has a cross-sectional area set to 95 mm 2 . Electric wire  200  has a length set to 2 m or more. The reason for this will be described with reference to  FIG.  19   . 
       FIG.  19    represents each terminal and each electric wire in temperature when male terminal  11  is connected to female terminal  21  and a current of 400 A is supplied for 30 minutes. In  FIG.  19   , a region R of a connecting portion of male terminal  11  and female terminal  21  is a region which attains highest temperature. 
     As shown in  FIG.  19   , when a vehicle-side electric wire  3  has a cross-sectional area of 95 mm 2 , and whether a portion up to 100 cm from male terminal  11  may or may not be cooled with water, it has been confirmed that a portion of vehicle-side electric wire  3  away from female terminal  21  by 100 cm is stable in temperature (or an effect of heat generated at the connecting portion of male terminal  11  and female terminal  21  is substantially negligible). 
     Furthermore, when the portion is water-cooled, and whether vehicle-side electric wire  3  may have a cross-sectional area of 70 mm 2  or 95 mm 2 , it has been confirmed that the portion of vehicle-side electric wire  3  away from female terminal  21  by 100 cm is stable in temperature (or an effect of heat generated at the connecting portion of male terminal  11  and female terminal  21  is substantially negligible). 
     From the above results, it can be seen that, by setting electric wire  200  to have a length of 2 m or more, an effect of heat generated at a connecting portion of one male terminal  11  and one female terminal  21  on a connecting portion of the other male terminal  11  and the other female terminal  21  via the electric wire is negligible. Thus, in the present embodiment, electric wire  200  is set to have a length of 2 m or more. 
     Each crimp terminal  300  is connected to an end  210  of electric wire  200 . Each crimp terminal  300  has a crimp portion  310  and a crimp-side flange  320 . 
     Crimp portion  310  crimps end  210  of electric wire  200 . 
     Crimp-side flange  320  is connected to crimp portion  310 . Crimp-side flange  320  is formed flat. Crimp-side flange  320  is provided with an insertion hole (not shown). Crimp-side flange  320  is fixed to female-side flange  130  by a bolt B and a nut (not shown). Bolt B is inserted into insertion hole  130   h  of female-side flange  130  and the insertion hole of crimp-side flange  320 . 
     Adjustment member  400  can adjust contact resistance of female terminal  100  and male terminal  11 . Specifically, adjustment member  400  can apply an external force to each female terminal  100  to reduce each female terminal  100  in diameter. Adjustment member  400  includes an annular band  410 , a metal band  420 , and an adjustment unit  430 . 
     Annular band  410  is attached around the plurality of contact pieces  110 . Annular band  410  surrounds the entire circumference of the plurality of contact pieces  110 . Annular band  410  is made of an electrically and thermally insulating material (resin or the like). In the direction parallel to center axis A, annular band  410  is smaller in length than slit  112 S. 
     Metal band  420  is wrapped around annular band  410 . Metal band  420  can apply an external force to the plurality of contact pieces  110  of female terminal  100  to reduce the plurality of contact pieces  110  in diameter. 
     Adjustment unit  430  can adjust a force applied by metal band  420  to clamp the plurality of contact pieces  110  (or reduce the plurality of contact pieces  110  in diameter). Specifically, adjustment unit  430  adjusts metal band  420  in diameter to adjust the clamping force. Adjustment unit  430  has a screw capable of adjusting metal band  420  in diameter. 
     A method for evaluating charging connector  5  in coolability by using evaluation jig  50  will now be described. Specifically, charging connector  5  is evaluated in coolability by connecting the pair of female terminals  100  of evaluation jig  50  to the pair of male terminals  11  of male connector  10 . This evaluation method includes a removing step, a connecting step, an adjusting step, and an evaluating step. 
     The removing step is a step of removing a portion of each tubular wall  17  of male casing  15 . Specifically, as shown in  FIGS.  14  to  16   , in the removing step, each tubular wall  17  is partially removed to form around male terminal  11  an operating space  17 S allowing an operation to be performed therein via adjustment unit  430  to adjust the external force. This partially exposes each male terminal  11 . Thus, the removing step removes a portion other than a portion capable of suppressing a short circuit of male terminals  11  or male terminal  11  and other terminals  12  to  14 , that is, a portion of tubular wall  17  where paired tubular walls  17  face each other. In the present embodiment, a portion of tubular wall  17  outside male terminal  11  in a direction of an imaginary line connecting male terminal  11  and protective grounding terminal  12  is removed. 
     The connecting step is a step of connecting the pair of female terminals  100  of evaluation jig  50  to the pair of male terminals  11 . In the connecting step, in a state in which each female terminal  100  has the plurality of contact pieces  110  with annular band  410  and metal band  420  attached thereto, female terminal  100  is connected to male terminal  11 . As shown in  FIGS.  17  and  18   , in the connecting step, female terminal  100  is inserted until distal end portion  112   a  of each flexible piece  112  contacts surface  16 S of bottom wall  16  of male casing  15 .  FIG.  17    shows one female terminal  100  alone receiving male terminal  11 . 
     The adjusting step is a step of adjusting a connection state of male terminal  11  and female terminal  100 . Specifically, in the adjusting step, the external force (the clamping force by metal band  420 ) is adjusted by adjustment unit  430 . More specifically, in the adjusting step, the external force is adjusted by operating adjustment unit  430  with an operating tool (not shown) in operating space  17 S so that contact resistance between male terminal  11  and female terminal  100  falls within a prescribed range. In this step, for example, from above in  FIG.  17   , the clamping force of adjustment unit  430  is adjusted with the operating tool. 
     In the adjusting step, the external force is preferably adjusted so that the contact resistance is 0.06 mΩ or more and 0.15 mΩ or less, more preferably 0.08 mΩ or more and 0.1 mΩ or less. 
     Herein, as shown in  FIG.  18   , the contact resistance is measured by a resistance value between a point P 1  of 4.5 mm from surface  16 S of bottom wall  16  and a point P 2  of 43 mm from surface  16 S of bottom wall  16 . The contact resistance may be measured with a milliohm tester or may be determined by a voltage drop caused when a current of 400 A is supplied. Point P 2  is in a vicinity of a boundary between a region affected by a standard applied in designing male connector  10  including male terminal  11  and a region unaffected thereby. 
     In the evaluating step, in a state with male terminal  11  and female terminal  100  connected together, a charging current of 400 A is supplied for 30 minutes, and the charging connector is evaluated in coolability by whether male terminal  11  and female terminal  100  have a temperature of 90° C. or lower. Whether male terminal  11  and female terminal  100  have such a temperature may be detected with a temperature sensor (not shown) provided to male terminal  11  or female terminal  100 . 
     Thus, by using evaluation jig  50  of the present embodiment, an amount of heat generated when charging connector  5  has a current passing therethrough can appropriately be evaluated. 
     The exemplary embodiment described above is a specific example of the following aspect. 
     An evaluation jig of the above embodiment comprises a pair of female terminals connectable to a pair of male terminals of a charging connector, and an electric wire connecting the paired female terminals, the electric wire having a cross-sectional area of 70 mm 2  or more and 95 mm 2  or less and a length of 2 m or more. 
     The evaluation jig that comprises the electric wire having a cross-sectional area of 70 mm 2  or more and 95 mm 2  or less and a length of 2 m or more allows an appropriate evaluation of an amount of heat generated (or a degree at which temperature rise) at a connecting portion of a male terminal and a female terminal without being substantially affected by the electric wire&#39;s heat radiation characteristic when a current passes (or the evaluation is made). Each terminal can thus be designed based on a result of the evaluation. 
     Preferably, the electric wire is made of copper. 
     Furthermore, an evaluation jig comprises a pair of female terminals connectable to a pair of male terminals of a charging connector, and an adjustment member that can adjust contact resistance of the female terminal and the male terminal, wherein the female terminal can be reduced in diameter, the adjustment member includes an annular band attached to an outer peripheral surface of the female terminal and formed in an annular shape surrounding the female terminal, a metal band attached to an outer peripheral surface of the annular band and capable of applying an external force to the female terminal to reduce the female terminal in diameter, and an adjustment unit that can adjust the external force applied by the metal band to the female terminal, and the annular band is made of an electrically and thermally insulating material. 
     The evaluation jig that comprises the adjustment unit that can adjust the external (or clamping) force applied by the metal band to the female terminal can adjust contact resistance between the male terminal and the female terminal, and furthermore, the annular band disposed between the female terminal and the metal band that is made of an electrically and thermally insulating material can suppress heat radiation caused at the metal band or the adjustment unit, and hence reduction in accuracy in evaluating an amount of heat generated at a connecting portion of the male terminal and the female terminal. 
     An evaluation method of the above embodiment is an evaluation method performed by connecting to a charging connector including a pair of male terminals that can be cooled with a coolant an evaluation jig including a pair of female terminals connectable to the pair of male terminals, by connecting the pair of female terminals of the evaluation jig to the pair of male terminals of the charging connector, for evaluating the charging connector in coolability, the method comprising: connecting the pair of female terminals to the pair of male terminals; adjusting a connection state of the male terminal and the female terminal so that a contact resistance between the male terminal and the female terminal is 0.06 mΩ or more and 0.15 mΩ or less; and, after the step of adjusting, evaluating the coolability depending on whether the male terminal and the female terminal have a temperature of 90° C. or lower when a charging current of 400 A is supplied to the male terminal and the female terminal for 30 minutes. 
     In this evaluation method, contact resistance between the male terminal and the female terminal is defined to fall within a range of 0.06 mΩ or more and 0.15 mΩ or less, and variation in evaluation results is suppressed. Therefore, the charging connector&#39;s coolability can be appropriately evaluated. Further, designing the female terminal of the charging inlet such that the contact resistance is 0.06 mΩ or more and 0.15 mΩ or less allows the male terminal and the female terminal to have a temperature of 90° C. or lower when a charging connector which obtains a good evaluation result in the step of evaluating is used to charge power with a charging current of 400 A supplied for 30 minutes. 
     Preferably, in the step of adjusting, the connection state is adjusted so that the contact resistance is 0.08 mΩ or more and 0.1 mΩ or less. 
     Further, an evaluation method of the above embodiment is an evaluation method performed by connecting to a charging connector including a pair of male terminals that can be cooled with a coolant and a bottom wall that holds the pair of male terminals in a state in which the pair of male terminals are inserted therethrough an evaluation jig including a pair of female terminals connectable to the pair of male terminals, by connecting the pair of female terminals of the evaluation jig to the pair of male terminals of the charging connector, for evaluating the charging connector in coolability, the method comprising: connecting the pair of female terminals to the pair of male terminals; and adjusting a connection state of the male terminal and the female terminal so that contact resistance between the male terminal and the female terminal falls within a prescribed range, wherein in the step of adjusting, a resistance between a point of 4.5 mm of the male terminal from a surface of the bottom wall and a point of 43 mm of the female terminal from the surface of the bottom wall is measured as the contact resistance. 
     In this evaluation method, a measurement point for contact resistance between the male terminal and the female terminal is determined, and an appropriate evaluation result of the coolability can be obtained. Specifically, a measurement point on the side of the male terminal is a point of 4.5 mm from the surface of the bottom wall. At this point, the male terminal has a sufficiently large cross-sectional area, and an effect on the contact resistance is reduced. A measurement point on the side of the female terminal is a point of 43 mm from the surface of the bottom wall. This point is in a vicinity of a boundary of a region affected by a standard applied in designing the charging connector including the male terminal and a region unaffected by the standard. Therefore, designing the female terminal of the charging inlet to achieve contact resistance equal to or less than that measured at this point suppresses the male and female terminals&#39; temperature to be a reference value or smaller when a charging connector that satisfies the standard is used to charge power. 
     Preferably, the evaluation method further comprises, after the step of adjusting, evaluating the coolability based on whether the male terminal and the female terminal have a temperature equal to or lower than 90° C. when a charging current of 400 A is supplied to the male terminal and the female terminal for 30 minutes. 
     Furthermore, an evaluation jig of the above embodiment includes a pair of female terminals connectable to a pair of male terminals of a charging connector, and an adjustment member that can adjust contact resistance of the female terminal and the male terminal, wherein the female terminal can be reduced in diameter, and the adjustment member can apply an external force to the female terminal to reduce the female terminal in diameter. 
     In this evaluation jig, the female terminal can be reduced in diameter and the adjustment member can apply an external force to the female terminal to reduce the female terminal in diameter, and contact resistance of the male terminal and the female terminal can be adjusted to fall within a prescribed range. Thus, the charging connector&#39;s coolability can be appropriately evaluated. 
     Furthermore, an evaluation method of the above embodiment is a method performed by connecting to a charging connector including a pair of male terminals that can be cooled with a coolant and a pair of tubular walls surrounding each of the paired male terminals an evaluation jig including a pair of female terminals that can be connected to the pair of male terminals and reduced in diameter and an adjustment member that can apply an external force to each of the paired female terminals to reduce the female terminal in diameter, by connecting the pair of female terminals of the evaluation jig to the pair of male terminals of the charging connector, for evaluating the charging connector in coolability, the method comprising: partially removing each tubular wall of the paired tubular walls to form around the male terminal an operating space allowing an operation to be performed therein via the adjustment member to adjust the external force; connecting the pair of female terminals to the pair of male terminals; and adjusting the external force in the operating space by the adjustment member so that contact resistance between the male terminal and the female terminal falls within a prescribed range. 
     In this evaluation method, an operating space allowing an operation to be performed therein to adjust external force is formed around a male terminal, and contact resistance can be adjusted in a state with the evaluation jig having a female terminal connected to the male terminal. 
     In the step of removing, the tubular wall preferably has removed a portion other than a portion at which the paired tubular walls face each other. 
     This suppresses short circuit of the male terminals. 
     Further, the adjustment member may include an annular band that is attached to an outer peripheral surface of the female terminal and formed in an annular shape surrounding the female terminal, a metal band that is attached to an outer peripheral surface of the annular band and can apply a force to the female terminal to reduce the female terminal in diameter, and an adjustment unit that can adjust a force applied by the metal band to clamp the female terminal, and the annular band may be made of an electrically and thermally insulating material. In this case, preferably, in the step of connecting, the pair of female terminals is connected to the pair of male terminals in a state with the annular and metal bands attached to each female terminal, and in the step of adjusting, the force applied by the metal band to clamp the female terminal is adjusted in the operating space. 
     Furthermore, an evaluation jig of the above embodiment comprises a female terminal connectable to a male terminal of a charging connector, the female terminal including a plurality of contact pieces which can each contact the male terminal and are spaced about a center axis, and a support portion to support the plurality of contact pieces, the plurality of contact pieces each having a flexible piece having a shape extending from the support portion in a direction parallel to the center axis, and a contact portion protruding toward the center axis from an inner surface of the flexible piece, the flexible piece forming a portion of a cylinder having the center axis, the flexible piece having a length equal to or larger than twice an outer diameter of the cylinder in a direction parallel to the center axis, the flexible piece being elastically deformable so that the flexible piece has a distal end portion to be displaceable in a radial direction of the cylinder relative to a proximal end portion of the flexible piece serving as a connecting portion of the flexible piece and the support portion, the contact portion having a shape curved so as to protrude inward in the radial direction. 
     In this evaluation jig, the flexible piece that has a length equal to or greater than twice the outer diameter of the cylinder in the direction parallel to the center axis is each less plastically deformable when the female terminal is repeatedly connected to and pulled out of the male terminal, and furthermore, each contact portion having a shape curved so as to protrude inward in the radial direction reliably contacts the male terminal. This allows prescribed contact resistance to be reliably reproduced and the charging connector&#39;s coolability to be evaluated appropriately. 
     Preferably, the contact portion has a shape extending in a direction parallel to the center axis. 
     Thus, even when the female terminal is connected to the male terminal in a state with the female terminal&#39;s center axis inclined relative to the male terminal&#39;s center axis, the female terminal is guided to have a posture so that the center axes match each other. 
     Preferably, the flexible piece has a protruding portion protruding from the contact portion in a direction parallel to the center axis away from the support portion. Preferably, the flexible piece and the contact portion have a boundary portion therebetween in a curved shape. 
     In this case, the contact portion preferably has an apex smaller in curvature than the boundary portion. 
     Furthermore, preferably, the flexible piece has a facing surface facing a flexible piece adjacent to the flexible piece of interest in the circumferential direction of the cylinder, and any pair of such facing surfaces facing each other in the circumferential direction are parallel to each other. 
     It should be understood that the presently disclosed embodiments are illustrative and not restrictive in any respect. The scope of the present invention is defined by the terms of the claims and intended to encompass any modifications within a meaning and scope equivalent to the terms of the claims.