JP2008145219A - Current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current sensor capable of preferably being applied for on-board use etc. , which is adopted with the constitution that the DC magnetic field that corresponds to the current to be measured is detected by the modulation of the magnetic flux caused by the Villari effect, and the coil formation for winding on the sensor body with wiring material which is operated comparatively easily and in the later process is capable of easily assembling to the wiring already wired and capable of changing the wiring of the measurement object accompanied by the design change. <P>SOLUTION: The sensor body 4, which is formed to the surface and the rear face of the semicircular piezoelectric plate 1, is sandwiched by the same shaped first magnetic plate 2 and the second magnetic plate 3 bonded integrally. A pair of sensor bodies 4 are prepared, and a pair of pick up soils 5 are provided respectively, and for measurement the edges of two sensor bodies 4 are abutted against each other so as to be connected magnetically. On the surface and the rear face of the piezoelectric plate 1, the electrode films are provided and polarized in the thickness direction, and the pick up coils 5 are formed by winding around and along the external profile. With respect to the wire 7 the sensor bodies are inter linked around the same, and measurement can be performed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a current sensor that detects the strength of a magnetic field generated by a current to be measured by a pickup coil, and more specifically, by applying a predetermined vibration force to a magnetic material associated with the pickup coil. Improvement of the sensor body structure in which a piezoelectric vibrator is integrally bonded to a magnetic material in a configuration that detects and detects a change in the magnetic field corresponding to the current to be measured by modulating it by causing an inverse magnetostriction effect (biliary effect). About.

  With respect to a current sensor that detects a direct current in a non-contact manner, there is an application that is required to be able to measure a large current and to perform measurement even in a severe environment where the temperature is relatively high. For example, in-vehicle applications mounted on vehicles, the specifications exceed those of general industrial applications, such as being small and robust, and having a wide operating temperature. Specifically, a current of about 50 amperes can be measured, and the engine room of the vehicle Therefore, it is necessary to be able to operate at least at about 130 ° C. In recent years, attention has been paid to fuel cell vehicles and hybrid vehicles, and current sensors have become important components.

  As a current sensor capable of detecting a large current, for example, a sensor using a Hall element is well known. This is because the Hall element is arranged in the gap part provided in the annular magnetic core, the electric wire through which the current to be measured flows is positioned inside the annular part, and the strength of the magnetic field generated by the current to be measured is detected by the Hall element ( (Hall voltage). However, a current sensor using a Hall element has many drawbacks because it is difficult to reduce the size because of the configuration in which the Hall element is sandwiched between gap portions of the magnetic core, and difficult to use in a high-temperature environment.

Further, as seen in Patent Document 1, there is a proposal of a technique in which a current sensor is configured by utilizing an inverse magnetostriction effect (billy effect). This is made by joining a piezoelectric member to an annular magnetic member and integrating them, winding a wire around the annular portion to form a pickup coil, and picking up the strength of the DC magnetic field generated by the DC current The structure which detects with a coil is taken. In order to detect the strength of the magnetic flux crossing the pickup coil, that is, the DC magnetic field, it is necessary to modulate this. For this reason, the piezoelectric member is vibrated in the diametrical direction by applying a predetermined AC voltage to the magnetic member. The magnetic force is modulated by causing an inverse magnetostriction effect (biliary effect) by applying a typical vibration force. Thereby, the change of the magnetic field corresponding to the current to be measured can be detected, and the current can be detected.
JP 2006-98332 A

  However, the current sensor using the inverse magnetostriction effect (bilari effect) as found in Patent Document 1 has the following problems.

  When mounting on the measurement target electric wire, there is a problem that it is difficult to assemble the wiring of the electric wire in a subsequent process, and it is not easy to change the measurement target electric wire due to a design change or the like. That is, as is apparent from the principle of measurement, the electric wire through which the current to be measured flows needs to be placed inside the annular portion to be in a penetrating state, which cannot be performed after the wiring on the electric wire side is completed. In addition, after the installation is completed, the wiring on the electric wire side cannot be removed unless it is cut once, and the cutting and reconnection of the wiring is necessary even on the changed electric wire side, which is complicated and troublesome.

  The pickup coil is formed by winding a wire around an annular sensor body. However, from the viewpoint of manufacturing work, the work of winding the wire into and out of the annular portion is not easy and takes time.

  The present invention solves the above-mentioned problems, and its purpose is to detect a DC magnetic field corresponding to the current to be measured by modulating the magnetic flux by the billiary effect, and to relatively form a coil that winds a wire around the sensor body. Providing a current sensor that can be easily applied to a pre-wired wire in a later process, easily change the wire to be measured with a design change, etc., and can be preferably applied to in-vehicle applications It is in.

  In order to achieve the above-described object, a current sensor according to the present invention is a current sensor that detects the strength of a magnetic field generated by a current to be measured by a pickup coil, and is a substantially semicircular or substantially U-shaped piezoelectric sensor. The first magnetic plate member and the second magnetic plate member having the same shape are sandwiched and joined to the front and back of the body plate member to form a sensor body. However, two sensor bodies are provided and each sensor body is provided. In this example, electrode films are provided on the front and back of the piezoelectric plate material, polarized in the thickness direction, and a wire is wound along the outer shape to form a pickup coil. For measurement, the sensor body is magnetically matched by matching the edges of each other. (Claim 1).

  Further, a predetermined gap is set between the gaps where the end edges of the sensor bodies abut each other, and the gap is adjusted according to the required characteristics.

  The sensor body is accommodated in a molded body made of a resin material, and the two sets of molded bodies are configured to be connected to each other so as to be openable and closable at one end side.

  Therefore, in the present invention, the sensor bodies having a substantially semicircular shape or a substantially U-shape are provided with two sets, and for the measurement, these two sets of sensor bodies are magnetically coupled by abutting the edges of each other. , Can be attached to the electric wire and can be measured.

  Since each sensor body is substantially semicircular or substantially U-shaped, it has an edge instead of being annularly closed, and it is easy to wrap the wire unlike the annularly closed member.

  In the current sensor according to the present invention, the substantially semicircular or substantially U-shaped sensor body is magnetically coupled by abutting the two edges of each other. That is, it can be easily assembled in a subsequent process with respect to a wired electric wire, and the electric wire to be measured can be easily changed due to a design change or the like.

  Since each of the sensor bodies is substantially semicircular or substantially U-shaped, it has an edge instead of being closed in an annular shape, and it is easy to wrap the wire. Therefore, there is an advantage that the coil formation for winding the wire around the sensor body can be relatively easily performed, and the manufacturing operation is facilitated.

  Since the two sensor bodies are annular with a gap, the piezoelectric material is divided into two parts, but this is not inconvenient. On the other hand, it can function appropriately as a piezoelectric vibrator, and the sensor output can be obtained satisfactorily.

  In addition, a current sensor is provided with a gap, but by changing the gap, the output characteristics can be adjusted as appropriate, thereby obtaining the required characteristics appropriately. As a result, the current sensor according to the present invention can be preferably applied to in-vehicle applications.

  FIG. 1 shows a preferred embodiment of the present invention. The current sensor of the present embodiment is formed by integrally bonding the first magnetic plate 2 and the second magnetic plate 3 having the same shape to the front and back of the substantially semicircular piezoelectric plate 1 in a sandwiched manner. Although the sensor body 4 is provided in two sets, each of which is provided with a pickup coil 5, and for the measurement, the sensor bodies 4 and 4 are magnetically coupled by abutting the edges of each other. It has a configuration.

  In each sensor body 4, electrode films are provided on the front and back surfaces of the piezoelectric plate material 1 to be polarized in the thickness direction, and the pickup coil 5 is formed by winding a wire material along the outer shape. And each sensor body 4 is accommodated in the molded object 6 shown in FIG. The two sets of molded bodies 6 and 6 are formed of a resin material, and are connected to each other so as to be openable and closable at one end side.

  For the measurement, the wired electric wire 7 is positioned inside the molded bodies 6 and 6 in the open state, and as shown in FIG. Here, the two sensor bodies 4 and 4 are magnetically connected to each other by abutting, but have a predetermined gap between the abutting spaces, and the portion of the molded body 6 becomes a gap member. ing. Therefore, the gap can be adjusted by appropriately changing the thickness of the portion of the molded body 6.

  Since the piezoelectric plate 1 is polarized in the thickness direction, it vibrates in the diameter direction by applying a predetermined AC voltage between the front and back electrode films. Then, the electric wire 7 through which the current I to be measured flows is positioned inside the annular portion, and the strength of the magnetic field generated by the current I to be measured is detected by the pickup coil 5. The shape of the piezoelectric plate 1 is not limited to a substantially semicircular shape, and may be formed in a substantially U shape, for example. Moreover, the molded object 6 can also be formed in a suitable shape.

  In this case, since the electric wire 7 is positioned in the annular portion, the magnetic flux due to the current I to be measured is generated in the circulation direction with respect to the magnetic plates 2 and 3. By applying an AC voltage to the piezoelectric plate member 1, when the magnetic field is constant, that is, in the state of the DC magnetic field, the magnetic flux density causes an increase or decrease in the corresponding amount, resulting in a change in the magnetic flux. That is, by applying a mechanical vibration force to the magnetic material plates 2 and 3, an inverse magnetostriction effect (biliary effect) is caused to modulate the magnetic flux. Due to this change in magnetic flux, an electromotive force is generated in the pickup coil 5, and the output of the pickup coil 4 increases or decreases in proportion to the magnitude of the DC magnetic field, that is, the current I to be measured. Therefore, the change in the magnetic field corresponding to the current I to be measured can be detected, and the current can be detected.

  Since this current sensor is composed of a piezoelectric material and a magnetic material, there is no problem when used in a high temperature environment, and the operating temperature range is wide. The current detection operation utilizes magnetic flux modulation due to the barrier effect, so that the size can be reduced unlike the configuration using the Hall element, and detection without being affected by the disturbance magnetic field can be performed. In addition, since the Hall element is a semiconductor, its radiation resistance is weak and low, but this current sensor has high radiation resistance. Furthermore, since the Hall element is arranged in the gap of the magnetic core, the sensitivity is low. On the other hand, the current detection configuration based on the barrier effect is highly sensitive and can detect a large current.

  In the present invention, the substantially semicircular or substantially U-shaped sensor body 4 includes two sets, and for the measurement, the two sets of sensor bodies 4 and 4 abut each other on the edges to magnetically. Therefore, it can be attached to the electric wire 7 so as to be measured. That is, it is possible to easily assemble the wired electric wire 7 in a later process, and the electric wire 7 to be measured can be easily changed due to a design change or the like.

  Since each of the sensor bodies 4 has a substantially semicircular shape or a substantially U shape, the sensor body 4 has an end edge instead of being annularly closed, and unlike the annularly closed member, it is easy to wrap the wire. Therefore, there is an advantage that the coil formation for winding the wire around the sensor body 4 can be relatively easily performed, and the manufacturing operation is facilitated.

  Since the two sensor bodies 4 and 4 are in a ring shape with a gap, the piezoelectric material part is divided into two parts, but this is not inconvenient and each is magnetic. It can function properly as a piezoelectric vibrator with respect to the body material. FIG. 4 is a graph showing the output characteristics of the current sensor, and is a result of simulating the configuration (a) according to the present invention having a gap and the conventional configuration (b) having no gap. As is apparent from the figure, the conventional configuration (b) having no gap has an output characteristic having a large hysteresis, and the configuration (a) according to the present invention having a gap has an output having a small hysteresis. Although it was characteristic, it was confirmed that the sensor output could be obtained satisfactorily.

  In addition, a current sensor is provided with a gap, but by changing the gap, the output characteristics can be adjusted as appropriate, thereby obtaining the required characteristics appropriately. As a result, the current sensor according to the present invention can be preferably applied to in-vehicle applications.

  In the present invention, a large DC current can be detected in a non-contact manner and the operating temperature becomes wide. Therefore, in-vehicle applications such as hybrid vehicles and electric vehicles, and applications of large current sensors such as solar power generation, wind power generation, and fuel cells. It is effective for.

1 is a perspective view showing a preferred embodiment of a current sensor according to the present invention. It is a perspective view which shows the molded object which accommodates a sensor body. It is a perspective view which shows the state of the current sensor at the time of measuring. It is a graph which shows the output characteristic of a current sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric board | plate material 2 1st magnetic body board | plate material 3 2nd magnetic body board | plate material 4 Sensor body 5 Pickup coil 6 Molded body 7 Electric wire

Claims (3)

A current sensor for detecting the strength of a magnetic field generated by a current to be measured by a pickup coil,
The first and second magnetic plate members having the same shape are sandwiched and joined to the front and back of the substantially semicircular or substantially U-shaped piezoelectric plate member to form a sensor body,
The sensor bodies are provided in pairs, and in each sensor body, an electrode film is provided on the front and back of the piezoelectric plate material, polarized in the thickness direction, and a wire is wound along the outer shape to form the pickup coil. A current sensor characterized in that two sensor bodies are magnetically coupled by abutting the edges of each other.   The current sensor according to claim 1, wherein a predetermined gap is set between a space where the end edges of the sensor bodies abut each other, and the gap is adjusted according to required characteristics. 3. The current according to claim 1, wherein the sensor body is accommodated in a molded body made of a resin material, and the two molded bodies are connected so as to be openable and closable on one edge side. Sensor.

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