JPH0483175A - Current detector - Google Patents

Abstract

PURPOSE:To realize voltage measurement of high accuracy and miniaturize a current detector at low cost by joining a conductor to a circuit substrate on which a voltage measuring circuit is mounted, and enclosing both of them in the same case, and using one part of the conductor as a portion for installing the detector. CONSTITUTION:Holes 21a, 21b to each of which a feed path 31 through which a current to be measured is made to flow is connected are provided at both ends of a conductor 21 taking the form of a band plate, which ends serve as supporting portions for installation. A voltage measuring circuit 32 uses a temperature compensating element 27 as one part of the circuit and is mounted on the surface of a circuit substrate 26 which faces the conductor 21. The integrated conductor 21 and the substrate 26 on which the circuit 32 is mounted are both enclosed in a case. Voltages are generated at both ends of a resistance 22 by a current flowing through the conductor 21 and are transferred to the circuit 32 and measured. The circuit 32 has a C/U portion 33 and a temperature compensating portion 34 and the element 27 provided to the compensating portion 34 is installed in the vicinity of the resistance 22 and compensates for changes in temperature in response to the temperature change of the resistance value of the resistance 22.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a current detection device, and more particularly to a current detection device using a conductor used for detecting current such as an automobile battery charging current or a load current.

(Prior Art) Conventionally, a vehicle-mounted current detection device using a conductor used for detecting current such as a current of an automobile battery charging current or a load current is disclosed in Japanese Utility Model Application Publication No. 191673/1983. Conventional in-vehicle current detection devices have a case containing a conductor (such as a fuse box) and a case containing a voltage measurement circuit, which are placed separately from each other, and the voltage generated in the conductor is measured by a voltmeter or other device using an electric wire. It was propagating to the measurement circuit. In addition, conductors only generate voltage when a current flows through them.

FIG. 9 shows an example of a current detection device using such a conventional conductor. A conventional current detection device 1 is composed of a conductor section 2 and a control unit section 3, and the conductor section 2 includes a conductor 4 made of one type of conductive metal, a case 5 that houses the conductor 4, and a case 5 for storing the conductor 4. A power supply line 6 connected to both ends of which the current to be detected flows, a voltage extraction terminal 7 which extracts the voltage generated in the conductor 4 due to the flow of current, and a voltage extracted from the voltage extraction terminal 7 and which propagates it to the control unit section 3. It is composed of electric wires 8. Also, control unit.

The part 3 includes a circuit board 9 mounted with a voltage measurement circuit (not shown) that receives the voltage propagated by the electric wire 8 as input and obtains an output for controlling other equipment, and the output obtained from the voltage measurement circuit. An electric wire 10 that propagates the voltage to the device to be controlled, and an electric wire 10 that supplies power and ground to the voltage measurement circuit, respectively.
, 12, a connector 13 for connecting the electric wires 10 to 12 and the electric wire 8 to a voltage measurement circuit, a case 14 for housing a circuit board 9 on which the voltage measurement circuit is mounted, and a mounting plate 15 for supporting this case 14. The case 14 has a slit portion 16 for supporting the circuit board 9 within the case 14.
, a locking part 1 for attaching the mounting plate 15 to the case 14
7. A dowel 18 is provided which is fitted into a fitting hole 15a formed in the mounting plate 15. Further, the mounting plate 15 is formed with a mounting hole 15b for connecting to other equipment.

(Problems to be Solved by the Invention) In such a conventional vehicle-mounted current detection device 1, the conductor 4 and the voltage measurement circuit are housed in separate cases 5.14 and installed at different locations, so that the device With the increase in size, a mounting plate is required to attach each case 5, 14 containing the conductor 4 or the voltage measuring circuit. In addition, since a temperature compensation element that compensates for changes in resistance due to temperature changes in the resistor cannot be installed near the conductor 4, highly accurate temperature compensation cannot be achieved. An expensive conductive metal with a small temperature coefficient had to be used. Furthermore, in order to propagate the normally extremely small voltage generated in the resistor to the voltage measurement circuit, it is necessary to use wires, connectors, etc., which reduces reliability due to the influence of electromagnetic wave noise from automobiles that is superimposed on the wires, and increases cost. It had the disadvantage of being expensive.

The purpose of the present invention was to solve such conventional problems, and it is possible to miniaturize the current detection device, eliminate electric wires, connectors, etc. for connecting the conductor and the control unit, and further improve the conductivity. Highly accurate temperature compensation is achieved by providing an installation part for holding a temperature compensation element that temperature-compensates the resistance value of a resistor that forms part of the body, and even when the temperature compensation element is not used, the total temperature The object of the present invention is to realize high-accuracy voltage measurement within a range and to obtain an inexpensive, small, and highly reliable current detection device.

(Means for Solving the Problems) The current detection device of the present invention is a voltage measuring device that measures the voltage generated across a conductor, a part of which is a supporting part, and a resistor formed integrally with the conductor. The present invention is characterized in that it is connected to a circuit board on which a circuit is mounted and is housed in the same case, and is further characterized in that a portion for disposing a temperature compensating element in close proximity to the conductor is formed.

(Function) According to the IT current detection device of the present invention, the current flowing through the conductor generates a voltage across the resistor, and the voltage is propagated to the voltage measurement circuit and measured. When the voltage measurement circuit 43 has a temperature compensation section, a temperature compensation element provided in the temperature compensation section is installed near the resistor, and performs temperature compensation in response to a temperature change in the resistance value of the resistor.

(Embodiments) Hereinafter, the current detection device of the present invention will be described in more detail with reference to embodiments shown in the accompanying drawings. FIG. 1 shows a current detection device according to an embodiment of the present invention, and FIG. 2 shows only a conductor.

A strip-shaped conductor 21 used in the current detection device 20 according to this embodiment is attached to a hole 21 at both ends of which is used as a support portion to connect a power supply path 31 (FIG. 4) through which a current to be measured flows.
a and 21b are provided, and the length is inward from the holes 21a and 21b, and the radius W, the thickness D, and the specific resistivity ρ of the metal of the conductor are
A resistor 22 (shaded area) is formed having a resistance value calculated from .

The circuit board 2 is configured to transmit the voltage generated by the current flowing through the resistor 22 to the circuit board 26 on which the voltage measurement circuit 32 is mounted.
Voltage extraction terminals 23a and 23b connected to the resistor 22 are provided on one side of the conductor 21 by being bent from both ends of the resistor 22 into an abbreviated shape.

On the other side of the conductor 21, the terminals 23a, 2
3b, a joining terminal 24a is joined to the circuit board 26.
, 24b is inside the hole 213.21b and the resistor 22
It is bent into an abbreviated shape on the outside of both ends. The conductor 21 includes a temperature compensation element 2 mounted on a circuit board for the purpose of compensating for temperature changes in the resistance value of the resistor 22.
A bending part 25, in which the temperature sensing part 27a of No. 7 is arranged close to each other, is bent into a substantially U-shape on one side of the conductor 21, outside both ends of the resistor 22, and inside the holes 21a and 2.1b. ing.

FIG. 4 is an explanatory diagram showing a simple circuit configuration of the current detection device 20 of this embodiment. The current flowing through the conductor 21 described above generates a voltage across the resistor 22, and the voltage is propagated to the voltage measuring circuit 32 and measured. Voltage measurement circuit 32
has a C/U section 33 and a temperature compensation section 34, and a temperature compensation element 27 provided in the temperature compensation section 34 is installed near the resistor 22, and responds to temperature changes in the resistance value of the resistor 22 and performs temperature compensation. conduct.

As shown in FIG. 1, the circuit board 26 on which the voltage measurement circuit 32 as described above is mounted is located on the side where the bent portion 25 formed on the conductor 21 and bent into a substantially U-shape exists, and on the side where the voltage extraction terminal is present. 23a23b, joining terminals 24a, 24
b is arranged on the plane of the bent side. Holes 282-28d are formed in the circuit board 26, and lands 29a-29d are provided in each hole.

A pattern 30 connected to the input of the voltage measuring circuit is wired from the lands 29a and 29b. The voltage generated across the resistor 22 by the current flowing through the power supply line 31 connected to the conductor 21 is generated through the holes 28a of the voltage extraction terminals 23a and 23b.

Voltage extraction terminal 23a is inserted into 28b and soldered to lands 29a and 29b.

The voltage is transmitted from 23b to the input of the voltage measuring circuit 32 through a pattern 30 connected to lands 29a and 29b. At the same time, the circuit board 26 is connected to each land 29a, 29b as described above.
The voltage output terminals 23a, 23b are soldered to the lands 29C, 29 inserted into the holes 28c, 28d, respectively.
It is joined to the conductor 21 by the joining terminals 24a and 24b soldered to d.

The voltage measurement circuit 32 uses the temperature compensation element 27 as one element of the circuit, and is mounted on the surface of the circuit board 26 facing the conductor 21. The temperature compensation element 27 has a lead portion 27b and a temperature sensing portion 27a.
The lead portion 27b is bent parallel to the conductor 21, and the temperature sensing portion 27a is arranged so as to be sandwiched within a substantially U-shaped groove of the bent portion 25, as shown in FIG. By arranging the temperature sensing portion 27a within the bending portion 25, the temperature sensing portion 27a is sensitive to temperature changes in the bending portion 25, temperature changes in the conductor 21, that is, temperature changes in the resistor 22 from both upper and lower surfaces facing the bending portion 25. React quickly and accurately. In this way, the conductor 21 is joined to the circuit board 26, and the four terminals 23a to 23a, two of which transmit the detected voltage to the voltage measurement circuit 32, are connected to the circuit board 26.
23d, the conductor 21 and the circuit board 26 are integrated, and an electric wire for extracting the voltage from the conductor 21 and transmitting it to the voltage measurement circuit 32 is not necessary. Furthermore, by having the bent portion 25 in which the temperature sensing portion 27a of the temperature compensation element 27 is arranged, it is possible to accurately and quickly compensate for temperature changes in the resistance value due to the ambient temperature of the conductor 21, self-heating of the resistor 22, etc. .

The circuit board 26 on which the conductor 21 and voltage measuring circuit 32 integrated as shown in FIG. 1 are mounted is housed in a case 35 as shown in FIG. The case 35 has an open top surface and is provided with a connector 36. The connector 36 includes a power terminal 36a, a ground terminal 36b, and a ground terminal 36b of the voltage measurement circuit 32.
It has an output terminal 36C of the voltage measurement circuit 32. The conductor portion bent downward into a convex shape and the circuit board 26, excluding both ends where the holes 21a and 21b for power supply line connection are formed, are inserted into the case 35 through the open top surface, and then the resin 37 is inserted into the case 35.
It is embedded and fixed in the case 35 by pouring it into the case 35.

FIG. 6 shows an example in which the current detection bag 220 of the above-mentioned embodiment constructed in this manner is attached to the fuse box 38. Within 3 days of the fuse box, the current detection device 2
A screw 41 is inserted through holes 21a and 21b formed at both ends of the conductor 21 at one end of a power supply connection terminal plate 39 for connecting 0 to a power supply (not shown) and a mounting plate 40 made of conductive metal. The other end of the mounting plate 40 is connected via a fuse 43 to a load connection terminal plate 42 which is connected to a load (not shown). Furthermore, openings 44a44b are formed in the fuse box 3 to connect cords (not shown) to each terminal plate 39,42. With this configuration, the current flowing from the power source passes through the cord to the power supply connection terminal plate 39, the conductor 21 to the current detection device 20, the mounting plate 40, and so on. Hughes 43. It flows into the load through the load connection terminal plate 42 and the cord connected thereto. In this way, by incorporating the conductor 21 to form a single current detection device 20 and using the conductor 21 itself as the mounting part of the current detection device 20, it is possible to separate the voltage measurement circuit 32 from a separate one as in the conventional case. There is no need for a mounting means for mounting the case, and the current detection bag N20 can be made smaller.

FIG. 7 shows a current detection device 50 according to another embodiment of the present invention.
It is shown. In the current detection device 50 of this embodiment,
The conductor 21 and the circuit board 26 are bonded to terminals 24a and 24b.
ζInner wall protrusions 51 are placed inside the case 51 without depending on the
A, 51b, etc. are used to support each circuit board 2.
6 and the conductor 21 are connected via an electric wire 52 instead of the voltage extraction terminals 23a and 23b. Then, the resin 37 is poured into the case 51 as in the previous embodiment, and is embedded and fixed in the conductor 21, the circuit board 26, and the case 51. The current detection device 50 of such an embodiment also provides the same effects as the above-mentioned embodiments.

Furthermore, FIG. 8 shows another example of the conductor in the current detection device of the present invention. This conductor 61 has a resistor 62 made of a conductive metal with a small temperature coefficient integrally formed in the center part (shaded area) of the part bent convexly downward. Unlike the conductor 21 in the embodiment shown in the figure, there is no bent part that sandwiches the temperature sensing part of the temperature compensating element. Therefore, as a matter of course, there is no temperature compensation element in the voltage measurement circuit mounted on the circuit board Fi26 assembled to this conductor 61. In this way, the resistance 6 in the conductor
Similar effects can be expected even if only the conductor 2 is made of a conductive metal with a small temperature coefficient, and the cost can be lowered than when the entire conductor is made of an expensive conductive metal with a small temperature coefficient.

(Effects of the Invention) As explained above, according to the current detection device of the present invention,
By joining the conductor and the circuit board on which the voltage measurement circuit is mounted and placing them in the same case, and by using a part of the conductor as the mounting part of the current detection device, a separate mounting means for supporting the current detection device can be created. This eliminates the need for smaller size and cost reduction. In addition, by directly connecting the voltage output terminal provided on the conductor to the input cover turn of the voltage measurement circuit mounted on the circuit board, the detected voltage can be transmitted to the voltage measurement circuit without going through wires, connectors, etc., and can be superimposed on the wire. High reliability can be obtained without being affected by t-magnetic wave noise from automobiles. Further, by providing the conductor with a bent portion that sandwiches the temperature compensation element, and attaching the temperature compensation element to this bent portion, the temperature compensation element can be installed near the conductor, and temperature changes in resistance value can be compensated for with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an assembly of a conductor and a circuit board in a current detection device according to an embodiment of the present invention, FIG. 2 is a perspective view of the conductor according to the embodiment, and FIG. m in the diagram
4 is a circuit diagram of the current detection device of the present invention, and FIG. 5 is a perspective view of the current detection device according to the embodiment of the present invention, FIG. 6 is a plan view showing a fuse box to which the current detection device of FIG. 5 is attached, FIG. 7 is a sectional view of a current detection device according to another embodiment of the present invention, and FIG. FIG. 9 is a front view showing an example of this, and FIG. 9 is a perspective view showing a conventional current detection device. 20... Current detection device, 21... Electric conductor, 22...
・Resistance, 218.21b...hole, 25...bending part,
26...Circuit board, 27...Temperature sensing portion of temperature compensation element, 35...Case. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Masuo Oiwa Figure 26: Circuit board E4 Figure 3 Figure 5 Figure 6 Figure 7 Figure 8 Figure I Figure 9

Claims (2)

[Claims] (1) Directly connect a conductor, a part of which is a support for mounting, and a circuit board mounting a voltage measurement circuit that measures the voltage generated in a resistor integrally formed on the conductor, and and the circuit board housed in the same case. (2) A conductor with a portion as a mounting support, a voltage measurement circuit that measures the voltage generated in a resistor formed integrally with the conductor, and compensation for changes in the resistance value of the resistor due to temperature changes. What is claimed is: 1. A current detecting device comprising: a circuit board on which a means for detecting a temperature is mounted; and a circuit board on which a means for detecting a temperature is mounted, housed in the same case, and a portion for disposing the temperature compensating element in close proximity to the conductor is provided.