Abstract:
An electric current sensor includes: a core having a ring shape and including a plurality of core pieces, which are laminated and integrated to provide the core; a magnetic gap disposed on a predetermined part of the core; a Hall element disposed in the magnetic gap; a body for accommodating the core and the Hall element; and a seal member for sealing the core and the Hall element into the body. Each core piece has a thin plate shape, and the core includes deformation preventing means for preventing a deformation of the magnetic gap.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based on Japanese Patent Application No. 2004-125355 filed on Apr. 21, 2004, and No. 2004-125356 filed on Apr. 21, 2004, the disclosures of which are incorporated herein by reference.  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates to an electric current sensor having a magnetic gap.  
       BACKGROUND OF THE INVENTION  
       [0003]     An electric current sensor having the core of a ring shape, the magnetic gap formed by cutting and opening one portion of this core, and the Hall element arranged in this magnetic gap is conventionally known. The sensor is disclosed in, for example, Japanese Patent Application Publication No. 2002-296305. In this electric current sensor, the core and the Hall element are stored to a storing portion opened in the upper portion of a box body, and the interior of this storing portion is filled with a sealant of a synthetic resin material. The core and the Hall element are sealed by hardening this sealant.  
         [0004]     In the electric current sensor, an electric current flowed to an electrically conductive member inserted into the core of the ring shape is detected by the Hall element arranged in the magnetic gap. Namely, a magnetic flux is generated within the core by the electric current flowed to the electrically conductive member, and the Hall element generates a voltage (Hall voltage) due to the Hall effect corresponding to this magnetic flux. The Hall voltage generated by the Hall element not only corresponds to the magnetic flux within the core, but also corresponds to the electric current flowed to the electrically conductive member generating this magnetic flux. Therefore, it is said that the Hall voltage is a detecting signal of this electric current value.  
         [0005]     In this connection, for example, the electric current sensor is used to detect the electric current flowed to the electrically conductive member (bus bar) for connecting a car mounting battery of an automobile and a vehicle electric mounting article.  
         [0006]     The core and the Hall element are first attached into the storing portion to manufacture the electric current sensor. Next, the interior of the storing portion is filled with liquid having fluidity or the sealant of a gel shape by flowing this liquid or the sealant into the storing portion or dropping (potting) the liquid or the sealant. Subsequently, the core and the Hall element are sealed and fixed within the storing portion in a state in which the core and the Hall element are positioned within the storing portion by hardening the sealant.  
         [0007]     Here, the magnetic gap of the core is formed by cutting and opening one portion of the core. Therefore, stress generated by hardening the sealant is applied to the core, and the core of the ring shape is deformed, and the size shape of the magnetic gap is changed from a set value. Therefore, a problem exists in that accuracy and sensitivity of the electric current detection using the Hall element are reduced.  
         [0008]     In particular, when the sealant having thermosetting property is used, large stress is generated at the thermosetting time of the sealant by a linear expansion coefficient of this sealant. Therefore, the core is easily deformed by this stress.  
         [0009]     The sealant having small stress generated at the hardening time may be used to prevent the deformation of the core caused by hardening the sealant. However, since such a sealant is expensive, the problem of an increase in manufacture cost of the electric current sensor is caused.  
       SUMMARY OF THE INVENTION  
       [0010]     In view of the above-described problem, it is an object of the present invention to provide an electric current sensor having a magnetic gap, which is hardly deformed.  
         [0011]     An electric current sensor includes: a core having a ring shape and including a plurality of core pieces, which are laminated and integrated to provide the core; a magnetic gap disposed on a predetermined part of the core; a Hall element disposed in the magnetic gap; a body for accommodating the core and the Hall element; and a seal member for sealing the core and the Hall element into the body. Each core piece has a thin plate shape, and the core includes deformation preventing means for preventing a deformation of the magnetic gap.  
         [0012]     The core and the Hall element are first attached into a storing portion to manufacture the electric current sensor. Next, an interior of the storing portion is filled with liquid having fluidity or a sealant of a gel shape by flowing the liquid or the sealant into the storing portion, or dropping the liquid or the sealant. Subsequently, the core and the Hall element are sealed and fixed into the storing portion in a state in which the core and the Hall element are positioned within the storing portion by hardening the sealant.  
         [0013]     At this time, since the deformation preventing means is arranged in the core, the deformation of the magnetic gap is restrained by the deformation preventing means even when stress generated by hardening the sealant is applied to the core. Accordingly, no size shape of the magnetic gap is changed from a set value.  
         [0014]     Accordingly, the deformation of the magnetic gap caused by hardening the sealant is prevented and reductions in accuracy and sensitivity of the electric current detection using the Hall element can be avoided by arranging the deformation preventing means in the core.  
         [0015]     Any using material (e.g., various kinds of synthetic resin materials such as silicon, urethane, epoxy, etc.) may be used in the sealant if this using material is a nonmagnetic material having a preferable working property of the filling to the storing portion and able to reliably seal the core and the Hall element after the hardening.  
         [0016]     In particular, when the sealant having thermosetting property is used, large stress is generated at the thermosetting time of the sealant by the linear expansion coefficient of this sealant. Therefore, the core is easily deformed by this stress. However, since the deformation of the magnetic gap can be prevented, the sealant having the thermosetting property can be used.  
         [0017]     Accordingly, a limit with respect to the using material of the sealant is reduced, and the stress generated at the hardening time is large. Instead of this, a cheap seal material can be used. Therefore, manufacture cost of the electric current sensor can be reduced. Thus, the magnetic gap of the sensor is hardly deformed.  
         [0018]     Preferably, the magnetic gap is provided by a notch, which is disposed on an inner portion of the core, and the deformation preventing means is a connection portion for connecting the core at the notch. Preferably, the magnetic gap is provided by a notch, which is disposed on an outer portion of the core, and the deformation preventing means is a connection portion for connecting the core at the notch.  
         [0019]     In the electric current sensor, the connecting portion for connecting the core of at least one portion of the inside or the outside of the notch portion is arranged as the deformation preventing means. Therefore, even when the stress generated by hardening the sealant is applied to the core, the deformation of the notch portion is restrained by the connecting portion, and no size shape of the notch portion functioning as the magnetic gap is changed from a set value.  
         [0020]     Further, a core cutting piece may be made by shearing and processing a hoop member as a thin plate material of a suitable electrically conductive magnetic material. The notch portion arranged in the core cutting piece and the connecting portion may be simultaneously formed in shearing and processing the core cutting piece from the hoop member.  
         [0021]     Accordingly, it is not necessary to add a special manufacture process to form the notch portion and the connecting portion in the core cutting piece, and no manufacture cost of the core is increased by forming the notch portion and the connecting portion.  
         [0022]     If the width of the connecting portion of the core is widely set, the operation and the effect can be raised. However, if the width of the connecting portion is widened, the magnetic flux density of a magnetic path formed in the notch portion is reduced. Therefore, there is a fear that the function as the magnetic gap of the notch portion is obstructed and the accuracy and sensitivity of the electric current detection using the Hall element are reduced.  
         [0023]     Accordingly, the width of the connecting portion of the core is set by experimentally finding an optimum value by cut and try such that the operation and effect are sufficiently obtained and the accuracy and sensitivity of the electric current detection using the Hall element are further not reduced.  
         [0024]     Preferably, the magnetic gap is provided by a through-hole, which is disposed on a middle portion of the core, and the deformation preventing means is a connection portion for connecting the core at the through-hole.  
         [0025]     Preferably, the magnetic gap is provided by a slit, at which the core is separated. The deformation preventing means is an reinforcing member for connecting the core at the slit, and the deformation preventing member is disposed on an inner portion of the core. Preferably, the magnetic gap is provided by a slit, at which the core is separated. The deformation preventing means is a reinforcing member for connecting the core at the slit, and the deformation preventing member is disposed on an outer portion of the core. Preferably, the reinforcing member is adhered and fixed to the core.  
         [0026]     In the above cases, the reinforcing member adhered and fixed to the core so as to connect at least a portion of the inside or the outside of the magnetic gap is arranged as the deformation preventing means. Therefore, even when stress generated by hardening the sealant is applied to the core, the deformation of the magnetic gap is restrained by the reinforcing member, and no size shape of the magnetic gap is changed from a set value.  
         [0027]     Preferably, the magnetic gap is provided by a slit, at which the core is separated. The deformation preventing means is a regulating member, and the deformation preventing member is inserted in the gap without clearance in a case where the core is accommodated in the body.  
         [0028]     In the above electric current sensor, the regulating member nipped in the magnetic gap without any clearance at the storing time of the core into the storing portion of the box body is arranged as a deformation preventing means. Therefore, the deformation of the magnetic gap is restrained by the regulating member even when stress generated by hardening the sealant is applied to the core. Accordingly, no size shape of the magnetic gap is changed from a set value.  
         [0029]     Preferably, the deformation preventing means is inserted in the gap at an inner portion of the gap. More preferably, the deformation preventing means is inserted in the gap at an outer portion of the gap.  
         [0030]     In the above electric current sensor, the deformation of the magnetic gap can be reliably prevented since the regulating member is nipped in at least a portion of the inside or the outside of the magnetic gap.  
         [0031]     Preferably, the deformation preventing means is fully inserted in the gap so that the deformation preventing means surrounds the Hall element.  
         [0032]     In the above electric current sensor, the regulating member is entirely nipped in the magnetic gap by surrounding the circumference of the Hall element. Therefore, the sensor in which the regulating member is nipped in one portion of the magnetic gap, the deformation of the magnetic gap can be more reliably restrained. Therefore, the above operation and effect can be further raised. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]     The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:  
         [0034]      FIG. 1  is an exploded perspective view showing an electric current sensor according to a first embodiment of the present invention;  
         [0035]      FIG. 2  is a perspective view showing the sensor according to the first embodiment;  
         [0036]      FIG. 3  is a partial plan view showing a main part of the sensor according to the first embodiment;  
         [0037]      FIG. 4  is a partial plan view showing a hoop member of the sensor according to the first embodiment;  
         [0038]      FIG. 5  is an exploded perspective view showing an electric current sensor according to a second embodiment of the present invention;  
         [0039]      FIG. 6  is a perspective view showing the sensor according to the second embodiment;  
         [0040]      FIG. 7  is a partial plan view showing a main part of the sensor according to the second embodiment;  
         [0041]      FIG. 8  is a partial plan view showing a hoop member of the sensor according to the second embodiment;  
         [0042]      FIG. 9  is an exploded perspective view showing an electric current sensor according to a third embodiment of the present invention;  
         [0043]      FIG. 10  is a perspective view showing the sensor according to the third embodiment;  
         [0044]      FIG. 11  is a partial plan view showing a main part of the sensor according to the third embodiment;  
         [0045]      FIG. 12  is a partial plan view showing a hoop member of the sensor according to the third embodiment;  
         [0046]      FIG. 13  is an exploded perspective view showing an electric current sensor according to a fourth embodiment of the present invention;  
         [0047]      FIG. 14  is a perspective view showing the sensor according to the fourth embodiment;  
         [0048]      FIG. 15  is a partial plan view showing a main part of the sensor according to the fourth embodiment;  
         [0049]      FIG. 16  is an exploded perspective view showing an electric current sensor according to a fifth embodiment of the present invention;  
         [0050]      FIG. 17  is a perspective view showing the sensor according to the fifth embodiment;  
         [0051]      FIG. 18  is a partial plan view showing a main part of the sensor according to the fifth embodiment;  
         [0052]      FIG. 19  is an exploded perspective view showing an electric current sensor according to a sixth embodiment of the present invention;  
         [0053]      FIG. 20  is a perspective view showing the sensor according to the sixth embodiment;  
         [0054]      FIG. 21  is a partial plan view showing a main part of the sensor according to the sixth embodiment;  
         [0055]      FIG. 22  is an exploded perspective view showing an electric current sensor according to a seventh embodiment of the present invention;  
         [0056]      FIG. 23  is a perspective view showing the sensor according to the seventh embodiment;  
         [0057]      FIG. 24  is a partial plan view showing a main part of the sensor according to the seventh embodiment;  
         [0058]      FIG. 25  is an exploded perspective view showing an electric current sensor according to an eighth embodiment of the present invention;  
         [0059]      FIG. 26  is a perspective view showing the sensor according to the eighth embodiment; and  
         [0060]      FIG. 27  is a partial plan view showing a main part of the sensor according to the eighth embodiment. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     First Embodiment  
       [0061]      FIG. 1  is an exploded perspective view of a main portion for explaining the schematic construction of an electric current sensor  10  according to a first embodiment of the present invention.  
         [0062]      FIG. 2  is a perspective view of the electric current sensor  10 .  
         [0063]      FIG. 3  is a plan view of a main portion of the electric current sensor  10 .  
         [0064]     The electric current sensor  10  is constructed by a Hall element  12 , a core  14  (a core cutting piece  15 , a notch portion  14   a  and a connecting portion  14   b ), a box body  16  (a storing portion  17 , a connector mounting portion  18 , a circuit storing portion  19 , a core storing portion  20 , an insertion hole  25  and an outer circumferential wall  26 ), an electronic part  21 , wiring members  22  to  24 , an attachment fitting  27 , a sealant  29 , etc.  
         [0065]     The connecting portion  14   b  corresponds to deformation preventing means.  
         [0066]     The core  14  is formed by laminating and integrating plural core cutting pieces  15  of a thin plate shape. The core cutting piece  15  is formed by shearing-processing (press working) a suitable electrically conductive magnetic material (e.g., iron, an iron-based alloy, permalloy, etc.).  
         [0067]     The core  14  (i.e., the core cutting piece  15 ) has a ring shape approximately formed in a rectangular shape in which round portions are formed at four corners. The outside portion of one portion (one portion on the short side of the approximately rectangular shape in the illustrated example) of this ring shape is notched in a concave shape toward the inside so that the notch portion  14   a  is formed. The connecting portion  14   b  is formed by connecting the core  14  inside this notch portion  14   a . The notch portion  14   a  functions as a magnetic gap of the core  14 .  
         [0068]     In the box body  16  of a nonmagnetic material manufactured by synthetic resin, the storing portion  17  opened upward, and the connector mounting portion  18  of a sleeve shape opened on the side are integrally formed by injection molding.  
         [0069]     The storing portion  17  is constructed by connecting the circuit storing portion  19  approximately formed in a box shape, and the core storing portion  20  approximately formed in a double frame shape.  
         [0070]     Here, the circuit storing portion  19  is formed in a shape shallower than that of the core storing portion  20 . The bottom face  19   a  of the circuit storing portion  19  is arranged in a position higher than that of the bottom face  20   a  of the core storing portion  20 . The box body  16  is formed by a structure of a stepwise shape of two stages constructed by high and low stages.  
         [0071]     The connector mounting portion  18  is connected to the side of the circuit storing portion  19 . The box body  16  is approximately formed in an L-shape as a whole.  
         [0072]     The Hall element  12  is attached and fixed to the bottom face  19   a  of the circuit storing portion  19 . Further, plural electronic parts  21  of various kinds constituting a drive control circuit of the Hall element  12  are attached and fixed to the bottom face  19   a . An adhesive is used to connect and fix the Hall element  12  and each electronic part  21 .  
         [0073]     The Hall element  12  and each electronic part  21  are connected through the wiring member  22 , and each electronic part  21  is connected through the wiring member  23 . Further, an unillustrated connector terminal arranged within the connector mounting portion  18  and each electronic part  21  are connected through the wiring member  24 . Electric welding is used instead of soldering in the connection of the respective wiring members  22  to  24 .  
         [0074]     The insertion hole  25  of a rectangular shape for inserting an electrically conductive member described later is opened approximately at the center of the bottom face  20   a  of the core storing portion  20 . The height of the outer circumferential wall  26  of the insertion hole  25  is set so as to be equal to the height of the outer circumferential wall of the storing portion  17  (the circuit storing portion  19  and the core storing portion  20 ).  
         [0075]     The attachment fitting  27  is attached and fixed to the rear face side of the bottom face  20   a  of the core storing portion  20 . A through hole is formed in the attachment fitting  27 . The electric current sensor  10  can be attached and fixed to a fixing object (e.g., a member within the engine room of an automobile) by inserting a bolt into this through hole and screwing the bolt to the fixing object.  
         [0076]     The core  14  is stored into the storing portion  17 . Namely, the core  14  is fitted to the outer circumferential wall  26  of the insertion hole  25  within the core storing portion  20 . The core  14  is placed on the bottom face  20   a  of the core storing portion  20  such that the core  14  of the ring shape surrounds the insertion hole  25 .  
         [0077]     A short side portion of the core  14  having the notch portion  14   a  is projected into the circuit storing portion  19 . The Hall element  12  is arranged by forming a gap approximately in the central position of the notch portion  14   a  functioning as a magnetic gap so as not to come in contact with the core  14 . For example, the distance of the notch portion  14   a  is set to 2.5 mm, and the width of the Hall element  12  is set to 1.5 mm, and the gap between the Hall element  12  and the core  14  is set to 0.5 mm.  
         [0078]     The interior of the storing portion  17  is filled with the sealant  29  (a slanting line hatching portion shown in  FIGS. 2 and 3 ). A storing object (the Hall element  12 , the core  14 , the electronic part  21  and the wiring members  22  to  24 ) of the storing portion  17  is sealed by hardening the sealant  29 . The position relation of this storing object within the storing portion  17  is positioned and fixed.  
         [0079]     An unillustrated electrically conductive member of a detecting object is first inserted into the insertion hole  25  to use the electric current sensor  10  constructed in this way. Next, an unillustrated connector of an external device for inputting a detecting signal of the electric current sensor  10  is inserted into the connector mounting portion  18 . The external device and the unillustrated connector terminal within the connector mounting portion  18  are then connected.  
         [0080]     When an electric current is flowed to the electrically conductive member, a magnetic flux is generated within the core  14  by this electric current. The Hall element  12  arranged within a magnetic path formed in the notch portion  14   a  by this magnetic flux generates a voltage (Hall voltage) by the Hall effect corresponding to this magnetic flux.  
         [0081]     Here, the Hall voltage generated by the Hall element  12  not only corresponds to the magnetic flux within the core  14 , but also corresponds to the value of an electric current flowed to the electrically conductive member generating this magnetic flux. Therefore, it is said that the Hall voltage is a detecting signal of this electric current value. Therefore, the Hall voltage generated by the Hall element  12  is outputted to the above external device as the detecting signal.  
         [0082]     Accordingly, the electric current sensor  10  can detect the value of the electric current flowed to the electrically conductive member inserted into the core  14  of the ring shape by the Hall element  12  arranged in the notch portion  14   a  of the core  14 .  
         [0083]     In this connection, for example, the electric current sensor  10  is used to detect the value of the electric current flowed to the electrically conductive member (bus bar) for connecting a car mounting battery of an automobile and a vehicle electric mounting article.  
         [0084]     [Operation and Effect] 
         [0085]     In accordance with the sensor according to the first embodiment, the following operation and effect can be obtained.  
         [0086]     [1-1] A storing object (the Hall element  12 , the core  14 , the electronic part  21  and the wiring members  22  to  24 ) is first attached into the storing portion  17  so as to manufacture the electric current sensor  10 . Next, the interior of the storing portion  17  is filled with liquid having fluidity or the sealant  29  of a gel shape by flowing the liquid or the sealant  29  into the storing portion  17 , or dropping (potting) the liquid or the sealant  29 . Subsequently, the above storing object is sealed and fixed into the storing portion  17  in a state in which the above storing object is positioned within the storing portion  17  by hardening the sealant  29 .  
         [0087]     At this time, the core  14  is connected by the connecting portion  14   b  inside the notch portion  14   a  of the core  14 . Therefore, even when stress generated by hardening the sealant  29  is applied to the core  14 , deformation of the notch portion  14   a  is restrained by the connecting portion  14   b  and no size shape of the notch portion  14   a  functioning as a magnetic gap of the core  14  is changed from a set value.  
         [0088]     Accordingly, the deformation of the notch portion  14   a  caused by hardening the sealant  29  is prevented and reductions in accuracy and sensitivity of the electric current detection using the Hall element  12  can be avoided by arranging the connecting portion  14   b  in the core  14 .  
         [0089]     [1-2] Any using material (e.g., various kinds of synthetic resin materials such as silicon, urethane, epoxy, etc.) may be used in the sealant  29  if this using material is a nonmagnetic material having a preferable working property of the filling to the storing portion  17  and able to reliably seal the storing object (the Hall element  12 , the core  14 , the electronic part  21  and the wiring members  22  to  24 ) of the storing portion  17  after the hardening.  
         [0090]     In particular, when the sealant  29  having thermosetting property is used, large stress is generated by the linear expansion coefficient of this sealant  29  at the thermosetting time of the sealant  29 . Therefore, the core  14  is easily deformed by this stress. However, in the sensor according to the first embodiment, since the deformation of the notch portion  14   a  of the core  14  can be prevented, the sealant  29  having the thermosetting property can be used.  
         [0091]     Accordingly, in the sensor according to the first embodiment, a limit with respect to the using material of the sealant  29  is reduced, and the stress generated at the hardening time is large. Instead of this, a cheap sealing material can be used. Therefore, manufacture cost of the electric current sensor  10  can be reduced.  
         [0092]     [1-3]  FIG. 4  is a plan view of a hoop member  30  for forming the core cutting-piece  15  constituting the core  14 .  
         [0093]     The hoop member  30  is a long thin plate material formed by the above magnetic material. Plural core cutting pieces  15  are punched and made from the hoop member  30  by shearing-processing (press working) this hoop member  30  using a shearing process machine (press process machine).  
         [0094]     Plural guide holes  32  arranged in the longitudinal direction are formed so as to extend through the hoop member  30 . Each guide hole  32  functions as a perforation for feeding the hoop member  30  to the shearing process machine and positioning the hoop member  30 .  
         [0095]     Here, the notch portion  14   a  and the connecting portion  14   b  arranged in the core cutting piece  15  are simultaneously formed in shearing-processing the core cutting piece  15  from the hoop member  30 .  
         [0096]     Accordingly, it is not necessary to add a special manufacture process to form the notch portion  14   a  and the connecting portion  14   b  in the core cutting piece  15 , and no manufacture cost of the core  14  is increased by forming each of the notch portion  14   a  and the connecting portion  14   b.    
         [0097]     It is also considered that the connecting portion  14   b  is made by a member separated from the core  14  (core cutting piece  15 ), and the magnetic gap is formed by cutting and opening one portion of the ring shape of the core  14  similarly to the sensor disclosed in Japanese Patent Application Publication No. 2002-296305, and the connecting portion  14   b  of the separate member is fitted and fixed to the magnetic gap of the core  14 . However, in this case, it is not desirable since cost is increased in comparison with the first embodiment by cost provided by adding manufacture cost required to make the connecting portion  14   b  by the member separated from the core  14  (core cutting piece  15 ) and manufacture cost required to fit and fix this connecting portion  14   b  to the magnetic gap of the core  14 .  
         [0098]     [1-4] If the width W of the connecting portion  14   b  of the core  14  shown in  FIG. 3  is widely set, the operation and effect of the above [1-1] can be raised. However, if the width W of the connecting portion  14   b  is widened, the magnetic flux density of the magnetic path formed in the notch portion  14   a  is reduced. Therefore, there is a fear that the function as the magnetic gap of the notch portion  14   a  is obstructed and the accuracy and sensitivity of the electric current detection using the Hall element  12  are reduced.  
         [0099]     Accordingly, the width W of the connecting portion  14   b  of the core  14  is set by experimentally finding an optimum value by cut and try such that the operation and effect of the above [1-1] are sufficiently obtained and the accuracy and sensitivity of the electric current detection using the Hall element  12  are further not reduced.  
       Second Embodiment  
       [0100]      FIG. 5  is an exploded perspective view of a main portion for explaining the schematic construction of an electric current sensor  40  according to a second embodiment of the present invention.  
         [0101]      FIG. 6  is a perspective view of the electric current sensor  40 .  
         [0102]      FIG. 7  is a plan view of a main portion of the electric current sensor  40 .  
         [0103]      FIG. 8  is a plan view of the hoop member  30  for forming the core cutting piece  15  constituting the core  14 .  
         [0104]     In the second embodiment, the electric current sensor  40  differs from the electric current sensor  10  of the first embodiment in that a notch portion  14   d  is formed by notching the inside portion of one portion (one portion of the short side of an approximately rectangular shape in the illustrated example) of the ring shape of the core  14  (core cutting piece  15 ) toward the outside in a concave shape, and a connecting portion  14   c  is formed by connecting the core  14  outside this notch portion  14   d . The notch portion  14   d  functions as the magnetic gap of the core  14 . The connecting portion  14   c  corresponds to the deformation preventing means.  
         [0105]     Namely, the notch portion  14   a  and the connecting portion  14   b  of the first embodiment are respectively replaced with the notch portion  14   d  and the connecting portion  14   c  of the second embodiment.  
         [0106]     In the electric current sensor  40 , a short side portion of the core  14  having the notch portion  14   d  is projected into the circuit storing portion  19 , and the Hall element  12  is arranged by forming a clearance approximately in the central position of the notch portion  14   d  functioning as the magnetic gap so as not to come in contact with the core  14 .  
         [0107]     Thus, in the second embodiment, since the core  14  is connected by the connecting portion  14   c  outside the notch portion  14   d  of the core  14 , the deformation of the notch portion  14   d  is restrained by the connecting portion  14   c  even when stress generated by hardening the sealant  29  is applied to the core  14 . Hence, no size shape of the notch portion  14   d  functioning as the magnetic gap of the core  14  is changed from a set value.  
         [0108]     Accordingly, an operation and an effect similar to those of the first embodiment can be also obtained in the second embodiment.  
       Third Embodiment  
       [0109]      FIG. 9  is an exploded perspective view of a main portion for explaining the schematic construction of an electric current sensor  50  according to a third embodiment of the present invention.  
         [0110]      FIG. 10  is a perspective view of the electric current sensor  50 .  
         [0111]      FIG. 11  is a plan view of a main portion of the electric current sensor  50 .  
         [0112]      FIG. 12  is a plan view of a hoop member  30  for forming the core cutting piece  15  constituting the core  14 .  
         [0113]     The electric current sensor  50  of the third embodiment differs from the electric current sensor  10  of the first embodiment in that a through hole  14   e  of a rectangular shape is formed so as to extend through one portion (one portion of the short side of an approximately rectangular shape in the illustrated example) of the ring shape of the core  14  (core cutting piece  15 ), and a connecting portion  14   f  is formed by connecting the core  14  outside this through hole  14   e , and a connecting portion  14   g  is formed by connecting the core  14  inside the through hole  14   e . The through hole  14   e  functions as the magnetic gap of the core  14 .  
         [0114]     Namely, the notch portion  14   a  and the connecting portion  14   b  of the first embodiment are respectively replaced with the through hole  14   e  and each of the connecting portions  14   f ,  14   g  in the third embodiment.  
         [0115]     In the electric current sensor  50  of the third embodiment, a short side portion of the core  14  having the through hole  14   e  is projected into the circuit storing portion  19 , and the Hall element  12  is arranged by forming a gap approximately in the central position of the through hole  14   e  functioning as the magnetic gap so as not to come in contact with the core  14 .  
         [0116]     [Operation and Effect] 
         [0117]     The following operation and effect can be obtained in accordance with the third embodiment.  
         [0118]     [3-1] Since the core  14  is connected by the connecting portions  14   g ,  14   f  on both the inside and the outside of the through hole  14   e  of the core  14 , the deformation of the through hole  14   e  is restrained by each of the connecting portions  14   f ,  14   g  even when stress generated by hardening the sealant  29  is applied to the core  14 . Accordingly, no size shape of the through hole  14   e  functioning as the magnetic gap of the core  14  is changed from a set value.  
         [0119]     In accordance with the third embodiment in which the core  14  is connected by the connecting portions  14   g ,  14   f  on both the inside and the outside of the through hole  14   e  of the core  14 , the deformation of a portion (through hole  14   e ) functioning as the magnetic gap can be more reliably restrained in comparison with the first embodiment and the second embodiment in which the core  14  is connected by the connecting portions  14   b ,  14   c  on one side of the inside and the outside of the notch portions  14   a ,  14   d  of the core  14 . Therefore, the operation and effect of the above [1-1] and [1-2] of the first embodiment can be further raised.  
         [0120]     [3-2] The operation and effect of the above [3-1] can be raised if the widths Wa, Wb of the respective connecting portions  14   f ,  14   g  of the core  14  shown in  FIG. 11  are widely set. However, when the widths Wa, Wb of the respective connecting portions  14   f ,  14   g  are widened, the magnetic flux density of a magnetic path formed in the through hole  14   e  is reduced. Therefore, there is a fear that the function as the magnetic gap of the through hole  14   e  is obstructed, and the accuracy and sensitivity of electric current detection using the Hall element  12  are reduced.  
         [0121]     Accordingly, the widths Wa, Wb of the respective connecting portions  14   f ,  14   g  of the core  14  are set by experimentally finding an optimum value by cut and try such that the operation and effect of the above [3-1] are sufficiently obtained and the accuracy and sensitivity of the electric current detection using the Hall element  12  are further not reduced.  
       Fourth Embodiment  
       [0122]      FIG. 13  is an exploded perspective view of a main portion for explaining the schematic construction of an electric current sensor  60  according to a fourth embodiment of the present invention.  
         [0123]      FIG. 14  is a perspective view of the electric current sensor  60 .  
         [0124]      FIG. 15  is a plan view of a main portion of the electric current sensor  60 .  
         [0125]     The electric current sensor  60  of the fourth embodiment differs from the electric current sensor  10  of the first embodiment in the following points.  
         [0126]     [A] A magnetic gap S is formed by cutting and opening one portion (one portion of the short side of an approximately rectangular shape in the illustrated example) of the ring shape of the core  14  (core cutting piece  15 ).  
         [0127]     [B] A reinforcing member  62  of a plate shape is adhered and fixed to the inside portion of the magnetic gap S in the core  14 . The reinforcing member  62  is formed by a nonmagnetic material having sufficient strength. For example, there are a synthetic resin material, various kinds of metallic materials (aluminum alloy, copper alloy, etc.) as such a nonmagnetic material.  
         [0128]     The reinforcing member  62  corresponds to the deformation preventing means.  
         [0129]     Namely, the electric current sensor  60  is constructed by the Hall element  12 , the core  14  (core cutting piece  15 ), the box body  16  (the storing portion  17 , the connector mounting portion  18 , the circuit storing portion  19 , the core storing portion  20 , the insertion hole  25  and the outer circumferential wall  26 ), the electronic part  21 , the wiring members  22  to  24 , the attachment fitting  27 , the sealant  29 , the reinforcing member  62 , etc.  
         [0130]     [C] A short side portion of the core  14  having the magnetic gap S is projected into the circuit storing portion  19 , and the Hall element  12  is arranged by forming a gap approximately in the central position of the magnetic gap S so as not to come in contact with the core  14 .  
         [0131]     Thus, in the fourth embodiment, the reinforcing member  62  is adhered and fixed in the inside portion of the magnetic gap S of the core  14 , and the inside portion of the magnetic gap S is connected by this reinforcing member  62 . Therefore, the deformation of the magnetic gap S is restrained by the reinforcing member  62  even when stress generated by hardening the sealant  29  is applied to the core  14 . Hence, no size shape of the magnetic gap S is changed from a set value.  
         [0132]     Accordingly, in the sensor according to the fourth embodiment, an operation and an effect similar to those of the above [1-1] and [1-2] of the first embodiment can be obtained.  
       Fifth Embodiment  
       [0133]      FIG. 16  is an exploded perspective view of a main portion for explaining the schematic construction of an electric current sensor  70  according to a fifth embodiment of the present invention.  
         [0134]      FIG. 17  is a perspective view of the electric current sensor  70 .  
         [0135]      FIG. 18  is a plan view of a main portion of the electric current sensor  70 .  
         [0136]     The electric current sensor  70  of the fifth embodiment differs from the electric current sensor  60  of the fourth embodiment in that a reinforcing member  72  of a plate shape is adhered and fixed to the outside portion of the magnetic gap S in the core  14 . Similar to the reinforcing member  62  of the fourth embodiment, the reinforcing member  72  is formed by a nonmagnetic material having sufficient strength.  
         [0137]     The reinforcing member  72  corresponds to the deformation preventing means.  
         [0138]     Namely, the reinforcing member  62  of the fourth embodiment is replaced with the reinforcing member  72  of the fifth embodiment.  
         [0139]     In the fifth embodiment, the reinforcing member  72  is adhered and fixed to the outside portion of the magnetic gap S of the core  14 , and the outside portion of the magnetic gap S is connected by this reinforcing member  72 . Therefore, the deformation of the magnetic gap S is restrained by the reinforcing member  72  even when stress generated by hardening the sealant  29  is applied to the core  14 . Hence, no size shape of the magnetic gap S is changed from a set value.  
         [0140]     Accordingly, an operation and an effect similar to those of the fourth embodiment can be obtained in accordance with the fifth embodiment.  
         [0141]     The fourth embodiment and the fifth embodiment may be used together.  
         [0142]     Namely, the reinforcing member  62  similar to that in the fourth embodiment may be adhered and fixed to the inside portion of the magnetic gap S in the core  14 , and the reinforcing member  72  similar to that in the fifth embodiment may be also adhered and fixed to the outside portion of the magnetic gap S.  
         [0143]     Thus, the core  14  is connected by the reinforcing members  62 ,  72  on both the inside and the outside of the magnetic gap S. Therefore, the deformation of the magnetic gap S can be more reliably restrained in comparison with the fourth embodiment and the fifth embodiment in which the core  14  is connected by the reinforcing members  62 ,  72  on one of the inside and the outside of the magnetic gap S. Accordingly, the above operation and effect of the fourth embodiment can be further raised.  
       Sixth Embodiment  
       [0144]      FIG. 19  is an exploded perspective view of a main portion for explaining the schematic construction of an electric current sensor  80  of a sixth embodiment of the present invention.  
         [0145]      FIG. 20  is a perspective view of the electric current sensor  80 .  
         [0146]      FIG. 21  is a plan view of a main portion of the electric current sensor  80 .  
         [0147]     The electric current sensor  80  is constructed by the Hall element  12 , the core  14  (the core cutting piece  15  and the magnetic gap S), the box body  16  (the storing portion  17 , the connector mounting portion  18 , the circuit storing portion  19 , the core storing portion  20 , the insertion hole  25  and the outer circumferential wall  26 ), the electronic part  21 , the wiring members  22  to  24 , the attachment fitting  27 , a regulating member (stopper)  82 , the sealant  29 , etc.  
         [0148]     The regulating members  82  corresponding to the deformation preventing means.  
         [0149]     The core  14  (core cutting piece  15 ) is formed in a ring shape of an approximately rectangular shape in which round portions are formed at the four corners. The magnetic gap S is formed by cutting and opening one portion (one portion of the short side of the approximately rectangular shape in the illustrated example) of this ring shape.  
         [0150]     A short side portion of the core  14  having the magnetic gap S is projected into the circuit storing portion  19 . The Hall element  12  is arranged by forming a gap approximately in the central position of the magnetic gap S so as not to come in contact with the core  14 . For example, the clearance of the magnetic gap S is set to 2.5 mm, and the width of the Hall element  12  is set to 1.5 mm, and the gap between the Hall element  12  and the core  14  is set to 0.5 mm.  
         [0151]     The regulating member  82  approximately formed in a rectangular shape rises between the Hall element  12  on the bottom face  19   a  of the circuit storing portion  19  and the outer circumferential wall  26 . The arranging position and the size shape of the regulating member  82  are set such that the regulating member  82  is nipped without any clearance in the magnetic gap S of the core  14  when the core  14  is stored into the storing portion  17 . The regulating member  82  is constructed by a synthetic resin material of a nonmagnetic substance and is formed integrally with the box body  16  by injection molding.  
         [0152]     The interior of the storing portion  17  is filled with the sealant  29  (a slanting line hatching portion shown in  FIGS. 20 and 21 ). A storing object (the Hall element  12 , the core  14 , the electronic part  21 , the wiring members  22  to  24  and the regulating member  82 ) of the storing portion  17  is sealed by hardening the sealant  29 , and the position of this storing object within the storing portion  17  is positioned and fixed.  
         [0153]     When the electric current sensor  80  constructed in this way is used, an unillustrated electrically conductive member of a detecting object is first inserted into the insertion hole  25 . Next, an unillustrated connector of an external device for inputting a detecting signal of the electric current sensor  80  is inserted into the connector mounting portion  18 , and the external device and an unillustrated connector terminal within the connector mounting portion  18  are connected.  
         [0154]     When an electric current is flowed to the electrically conductive member, a magnetic flux is generated within the core  14  by this electric current. The Hall element  12  arranged within a magnetic path formed in the magnetic gap S by this magnetic flux generates a voltage (Hall voltage) using the Hall effect corresponding to this magnetic flux.  
         [0155]     Here, the Hall voltage generated by the Hall element  12  not only corresponds to the magnetic flux within the core  14 , but also corresponds to the value of the electric current flowed to the electrically conductive member generating this magnetic flux. Therefore, it is said that the Hall voltage is a detecting signal of this electric current value. Therefore, the Hall voltage generated by the Hall element  12  is outputted to the above external device as the detecting signal.  
         [0156]     Accordingly, the electric current sensor  80  can detect the value of the electric current flowed to the electrically conductive member inserted into the core  14  of the ring shape by the Hall element  12  arranged in the magnetic gap S of the core  14 .  
         [0157]     In this connection, for example, the electric current sensor  80  is used to detect the value of the electric current flowed to an electrically conductive member (bus bar) for connecting a car mounting battery of an automobile and a vehicle electric mounting article.  
         [0158]     [Operation and Effect] 
         [0159]     The following operation and effect can be obtained in accordance with the sixth embodiment.  
         [0160]     [6-1] A storing object (the Hall element  12 , the core  14 , the electronic part  21 , the wiring members  22  to  24  and the regulating member  82 ) is first attached into the storing portion  17  so as to manufacture the electric current sensor  80 . Next, the interior of the storing portion  17  is filled with liquid having fluidity or the sealant  29  of a gel shape by flowing the liquid or the sealant  29  into the storing portion  17 , or dropping (potting) the liquid or the sealant  29 . Subsequently, the above storing object is sealed and fixed into the storing portion  17  in a state in which the above storing object is positioned within the storing portion  17  by hardening the sealant  29 .  
         [0161]     At this time, since the regulating member  82  is nipped without any clearance in the magnetic gap S of the core  14 , the deformation of the magnetic gap S is restrained by the regulating member  82  even when stress generated by hardening the sealant  29  is applied to the core  14 . Accordingly, no size shape of the magnetic gap S is changed from a set value.  
         [0162]     Accordingly, in accordance with the sixth embodiment, the deformation of the magnetic gap S of the core  14  caused by hardening the sealant  29  is prevented and reductions in accuracy and sensitivity of electric current detection using the Hall element  12  can be avoided by arranging the regulating member  82 .  
         [0163]     [6-2] Any using material (e.g., various kinds of synthetic resin materials such as silicon, urethane, epoxy, etc.) may be used in the sealant  29  if this using material is a nonmagnetic material having a preferable working property of the filling to the storing portion  17  and able to reliably seal the storing object (the Hall element  12 , the core  14 , the electronic part  21 , the wiring members  22  to  24  and the regulating member  82 ) of the storing portion  17  after the hardening.  
         [0164]     In particular, when the sealant  29  having thermosetting property is used, large stress is generated at the thermosetting time of the sealant  29  by the linear expansion coefficient of this sealant  29 . Therefore, the core  14  is easily deformed by this stress. However, in accordance with the sixth embodiment, the deformation of the magnetic gap S can be prevented. Therefore, the sealant  29  having the thermosetting property can be used.  
         [0165]     Accordingly, in accordance with the sixth embodiment, a limit with respect to the using material of the sealant  29  is reduced and the stress generated at the hardening time is large. Instead of this, a cheap seal material can be used. Therefore, manufacture cost of the electric current sensor  80  can be reduced.  
         [0166]     [6-3] The regulating member  82  is formed integrally with the box body  16  by injection molding. Accordingly, in accordance with the sixth embodiment, it is not necessary to add a special manufacture process to form the regulating member  82 . Accordingly, no manufacture cost of the electric current sensor  80  is increased by arranging the regulating member  82 .  
         [0167]     In the above embodiment, the regulating member  82  and the box body  16  are integrally formed by injection molding. However, the regulating member  82  formed separately from the box body  16  may be also attached and fixed to the box body  16  (the bottom face  19   a  of the circuit storing portion  19 ).  
       Seventh Embodiment  
       [0168]      FIG. 22  is an exploded perspective view of a main portion for explaining the schematic construction of an electric current sensor  90  according to a seventh embodiment of the present invention.  
         [0169]      FIG. 23  is a perspective view of the electric current sensor  90 .  
         [0170]      FIG. 24  is a plan view of a main portion of the electric current sensor  90 .  
         [0171]     The electric current sensor  90  of the seventh embodiment differs from the electric current sensor  80  of the sixth embodiment in that the regulating member  82  is omitted and a regulating member  92  of the same size shape as the regulating member  82  is arranged instead of the regulating member  82 .  
         [0172]     The regulating member  92  corresponds to the deformation preventing means.  
         [0173]     Namely, the electric current sensor  90  is constructed by the Hall element  12 , the core  14  (the core cutting piece  15  and the magnetic gap S), the box body  16  (the storing portion  17 , the connector mounting portion  18 , the circuit storing portion  19 , the core storing portion  20 , the insertion hole  25  and the outer circumferential wall  26 ), the electronic part  21 , the wiring members  22  to  24 , the attachment fitting  27 , the sealant  29 , the regulating member  92 , etc.  
         [0174]     The Hall element  12  is attached and fixed between the outer circumferential wall  26  and the regulating member  92  on the bottom face  19   a  of the circuit storing portion  19 . The arranging position and the size shape of the regulating member  92  are set so as to be nipped without any clearance in the magnetic gap S of the core  14  when the core  14  is stored into the storing portion  17 . The regulating member  92  is constructed by a synthetic resin material of a nonmagnetic substance and is formed integrally with the box body  16  by injection molding.  
         [0175]     Namely, the regulating member  82  of the sixth embodiment is nipped in the inside portion of the Hall element  12  in the magnetic gap S. In contrast to this, the regulating member  92  of the seventh embodiment is nipped in the outside portion of the Hall element  12  in the magnetic gap S.  
         [0176]     Thus, in the seventh embodiment, the regulating member  92  is nipped without any clearance in the magnetic gap S of the core  14 . Therefore, even when stress generated by hardening the sealant  29  is applied to the core  14 , the deformation of the magnetic gap S is restrained by the regulating member  92  and no size shape of the magnetic gap S is changed from a set value.  
         [0177]     Accordingly, an operation and an effect similar to those of the sixth embodiment can be also obtained in the seventh embodiment.  
       Eighth Embodiment  
       [0178]      FIG. 25  is an exploded perspective view of a main portion for explaining the schematic construction of an electric current sensor  100  according to an eighth embodiment of the present invention.  
         [0179]      FIG. 26  is a perspective view of the electric current sensor  100 .  
         [0180]      FIG. 27  is a plan view of a main portion of the electric current sensor  100 .  
         [0181]     The electric current sensor  100  of the eighth embodiment differs from the electric current sensor  80  of the sixth embodiment in that the regulating member  82  of the sixth embodiment is omitted and a regulating member  102  is arranged instead of the regulating member  82 .  
         [0182]     The regulating member  102  corresponds to the deformation preventing means.  
         [0183]     Namely, the electric current sensor  100  is constructed by the Hall element  12 , the core  14  (the core cutting piece  15  and the magnetic gap S), the box body  16  (the storing portion  17 , the connector mounting portion  18 , the circuit storing portion  19 , the core storing portion  20 , the insertion hole  25  and the outer circumferential wall  26 ), the electronic part  21 , the wiring members  22  to  24 , the attachment fitting  27 , the sealant  29 , the regulating member  102 , etc.  
         [0184]     The regulating member  102  rises on the bottom face  19   a  of the circuit storing portion  19  and is formed in a shape in which a through hole extends through the central portion so that an opening is formed in a rectangular shape. The Hall element  12  is fitted to the through hole of the regulating member  102 , and the regulating member  102  surrounds the circumference of the Hall element  12 . The arranging position and the size shape of the regulating member  102  are set so as to be nipped without any clearance in the magnetic gap S of the core  14  when the core  14  is stored into the storing portion  17 . The regulating member  102  is constructed by a synthetic resin material of a nonmagnetic substance and is formed integrally with the box body  16  by injection molding.  
         [0185]     Thus, in the eighth embodiment, the regulating member  102  is nipped without any clearance in the entire magnetic gap S of the core  14 . Therefore, even when stress generated by hardening the sealant  29  is applied to the core  14 , the deformation of the magnetic gap S is restrained by the regulating member  102  and no size shape of the magnetic gap S is changed from a set value.  
         [0186]     In accordance with the eighth embodiment in which the regulating member  102  is nipped without any clearance in the entire magnetic gap S of the core  14 , the deformation of the magnetic gap S can be more reliably restrained in comparison with the sixth embodiment and the seventh embodiment in which the regulating members  82 ,  92  are nipped in one portion of the magnetic gap S of the core  14 . Therefore, the above operation and effect of the sixth embodiment can be further raised.  
         [0187]     Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims.