JP6955364B2 - Load cell - Google Patents

Description

The present invention relates to a load cell that detects the deforming force of a strain-causing body.

There is a load cell that detects the force when the strain is compressed or pulled. This type of load cell has a strain-causing body, and the strain-causing body is provided with a strain gauge bridge circuit. When a force is applied to the strain-causing body, the strain gauges are compressed or pulled to change the resistance value, so that the combined resistance value of the bridge circuit changes. When the combined resistance value changes, the output voltage of the bridge circuit changes, so this changed voltage is converted into the force received by the strain generator.

In general, a strain gauge is equipped with a strain gauge and other parts necessary for accurate force measurement, such as temperature sensing resistance. There are two types of load cells, one is a type in which strain gauges and parts are attached to the surface of the strain generating body, and the other is a type in which the strain gauge and parts are attached to the inside of the strain generating body.

Patent Document 1 below describes that a strain gauge is housed in a recess formed in an annular shape on the periphery of a hole formed in the strain-causing body, and the strain gauge is sealed by covering the recess with a thin-walled cylindrical tube. ing. Further, a gauge connection lead-out hole is formed from the recess to the outside of the strain-causing body, and after the connection wire is pulled out, it is sealed with a sealing material.

Microfilm of No. 64-585

In the above document, it is considered that the connecting wire is soldered to the strain gauge, and then the connecting wire is pulled out from the gauge connection lead-out hole from the strain gauge. The connecting wire is considered to be soldered to the strain gauge, in which case residual flux is considered to be present around the solder.

Flux is like "yani" that is contained in the solder to facilitate soldering, and may be used together with the solder even if it is not originally contained in the solder. After soldering, this flux has the property of diffusing around the solder. This is hereinafter referred to as residual flux.

Since the residual flux becomes conductive when it contains moisture, depending on the range in which the residual flux is diffused, the residual flux in that range may become moist and cause insulation failure. For example, when the residual flux is diffused between the force detecting circuit and the strain generating body, the strain generating body and the force detecting circuit may have continuity when moisture is included. Therefore, it is necessary to thoroughly clean the residual flux.

In the above document, the dent to which the strain gauge is attached is covered with a thin-walled cylindrical tube to prevent moisture, but it is conceivable that moisture may flow into the dent through the sealing material of the gauge connection lead-out hole.

Once the moisture has flowed into the dent, the rate at which the moisture depletes from the dent is considered to be slow. In the above document, since the strain gauge is adhered to the bottom of the recess formed in the hole in an annular shape, a special cleaning tool is used depending on the size and depth of the hole or the depth of the recess. Except when doing so, it can be difficult to get the cleaning solution to the residual flux. In particular, when the connecting wire or cable covers the residual flux, this problem becomes remarkable because it is necessary to put a finger in the hole to move each of them.

In particular, the above-mentioned document 1 does not describe how to store various parts such as gauge terminals and temperature-sensitive resistors, but when various parts are attached to a recess by soldering, the above-mentioned problem in cleaning the residual flux is solved. It becomes more prominent.

An object of the present invention is to provide a load cell capable of easily cleaning residual flux in order to solve the above problems.

In order to achieve the above object, the load cell according to the embodiment of the present invention includes a strain-causing body in which a recess is formed, and a strain gauge and a strain gauge in a direction from the inner surface of the recess toward the surface of the recess. While the component boards to which the components for forming the force detection circuit using the strain gauge are attached are sequentially housed, the components are not attached to the wall surface of the recess.
The recess is divided into a first recess on the front side of the strain-causing body and a second recess on the back surface side of the strain-causing body, and at least the component substrate is the first and second recesses. As a component board, they are separately distributed and stored in the first and second recesses.

According to this configuration, since the component on the component substrate is located on the surface side of the recess, the cleaning liquid can easily reach the residual flux with a strong pressure, and there is an advantage that the residual flux can be easily cleaned. In particular, when the cable covers the residual flux, the effect becomes remarkable. Further, as compared with the case where the component is attached to an appropriate place in the recess such as the wall surface of the recess, the component board to which the component is connected only needs to be stored in the recess, so that the work efficiency is improved.
In addition, since the parts necessary for force detection are stored in two recesses formed on the front side and the back side of the strain generating body, the force detection circuit can be installed in a narrow area where the force is concentrated. It can be stored and the load cell can be made compact.

Further, in the load cell of the present invention, connection lines are derived from the first and second component boards, and the number of the connection lines of the first component board is the number of the connection lines of the second component board. The number of connecting lines is smaller than the number, and any of the power supply line, the output line, and the cable derived from the first component board may be housed in the first recess.

According to this configuration, the number of wires in the first recess on the front surface side is smaller than that on the second recess side on the back surface side, so that the power supply line and output line are in the first recess on the front surface side. , It becomes easy to store any of the cables, and it becomes easy to move each of the power supply line, the output line, and the cable when cleaning the residual flux.

Further, in the load cell of the present invention, a gauge terminal used as a connection terminal for the strain gauge may be arranged below the component substrate.

According to this configuration, since the gauge terminal is arranged under the component substrate, when the component substrate is moved, if there is residual flux in the gauge terminal, the residual flux is exposed on the surface of the recess. This makes it easier to clean the residual flux at the gauge terminals.

Further, in the load cell of the present invention, the gauge terminal may be arranged side by side with the strain gauge in a direction parallel to the surface of the recess.

According to this configuration, the gauge terminals are arranged so as to line up with the strain gauge parallel to the surface of the recess. Therefore, when the component board is moved, if there is residual flux in the gauge terminal or strain gauge, the residual flux remains. The flux is exposed on the surface of the recess. This makes it easier to clean the residual flux of the gauge terminals and strain gauges.

Further, in the load cell of the present invention, the component may be attached to the recessed surface side of the component substrate.

According to this configuration, since the component is attached to the surface side of the recess, the component is exposed on the surface of the recess. Therefore, if there is residual flux around the component, it will be exposed, and it will be easier to clean the residual flux.

Further, in the load cell of the present invention, a protective member for the strain gauge may be interposed between the strain gauge and the component substrate.

According to this configuration, since the protective member is interposed between the strain gauge and the component substrate, the strain gauge can be appropriately protected from the lead wire protruding from the component substrate through the through hole.

Further, in the load cell of the present invention, a through hole is formed in the component substrate, and the protective member and the component substrate are fixed by a fixing member, and the through hole is fixed in the fixing member. A protective hole having a depth for protecting the strain gauge from a portion where the lead wire inserted into the through hole can protrude from the through hole may be formed corresponding to the through hole.

According to this configuration, the fixing member is formed with a protective hole for protecting the strain gauge from a part of the lead wire protruding from the through hole at a portion corresponding to the through hole of the component substrate. The strain gauge can be appropriately protected in cooperation with the protective member.

It is provided with a strain-causing body in which a recess is formed, and a strain gauge and a component for forming a force detection circuit using the strain gauge are attached in a direction from the inner surface of the recess toward the surface of the recess. While the component boards are stored in order, the components are not attached to the wall surface of the recess.
A protective member for the strain gauge is interposed between the strain gauge and the component substrate.
Further, through holes are formed in the component substrate, and the through holes are formed.
The protective member and the component substrate are fixed by a fixing member.
The fixing member is formed with a protective hole having a depth for protecting the strain gauge from a portion where a lead wire inserted into the through hole can protrude from the through hole, corresponding to the through hole. There is.

According to this configuration, according to this configuration, a protective member is interposed between the strain gauge and the component board, so that the strain gauge is appropriately protected from the lead wire protruding from the component board through the through hole. be able to.

Further, as the recess, the first recess on the surface of the strain-causing body and the second recess on the back surface of the strain-causing body are separately formed, and at least the strain gauges are the first and second. As the strain gauge of the above, the strain gauges may be separately distributed and stored in the first and second recesses.

According to this configuration, as compared with the case where all the strain gauges are stored in one recess, the deformation of each strain gauge is not distorted, so that accurate force detection is possible.

According to the present invention, the residual flux can be easily washed.

1A is a plan view, FIG. 1B is a front view, FIG. 1C is a bottom view, and FIG. 1D is a side view. Each is represented. It is a figure which shows the appearance example of the load cell of a reference example, FIG. 2 (E) is a cross-sectional view taken along the line AA of FIG. 1 (B), and FIG. The cross-sectional views of the arrows are shown respectively. It is a figure which showed typically the installation example of the load cell of the reference example, FIG. 3A shows a front view, and FIG. 3B shows a side view. It is a figure which shows an example of the circuit structure of the force detection circuit of the load cell of the reference example. It is the figure which represented the recess of the load cell of a reference example schematically. It is a figure which represented typically an example of the cross section of the load cell which concerns on one Embodiment of this invention. It is a figure which shows an example of the circuit structure of the force detection circuit which concerns on one Embodiment of this invention. It is a figure which represented the recess of the load cell of this invention schematically. It is a figure which showed the structural example of the double-sided tape. It is a figure for demonstrating an example of the storage procedure of the component in the load cell of this invention, FIG. 10A is a front view, FIG. 10B is a cross-sectional view taken along the line AA of FIG. Represents each. It is a figure for demonstrating an example of the storage procedure of the component | component in the load cell of this invention, and shows the front view. It is a figure for demonstrating an example of the storage procedure of the component | component in the load cell of this invention, and shows the cross-sectional view taken along the line AA of FIG.

As the S-shaped load cell, the load cell of FIGS. 1 to 5 can be considered. First, the S-shaped load cell of FIGS. 1 to 5 is given as a reference example of the present invention, and the details thereof will be described.

1 and 2 show an example of the appearance of this type of S-shaped load cell. 1 (A) is a plan view, FIG. 1 (B) is a front view, FIG. 1 (C) is a bottom view, FIG. 1 (D) is a side view, and FIG. 2 (E) is A-A of FIG. 1 (B). A cross-sectional view taken along the line A, FIG. 2 (F) is a cross-sectional view taken along the line BB of FIG. 1 (B). As shown in FIG. 1 (B), this S-shaped load cell has an S-shaped appearance when viewed from the front, and will be simply referred to as a "load cell" hereafter.

As shown in FIG. 1B, the load cell 1A includes an S-shaped strain generating body 10 when viewed from the front. The strain-causing body 10 has a rectangular shape (here, a rectangular shape) when viewed from above or below (upper or lower in the paper surface direction in FIG. 1). Further, the strain generating body 10 also has a rectangular shape (here, a rectangular shape) when viewed from the side (in each direction on the left and right sides of the paper surface in FIG. 1).

A recess 11A is formed on the front side as a first recess and a recess 11B is formed on the back side as a second recess at a predetermined position (for example, a force concentration location) of the strain generating body 10. .. In the load cell 1A, a cable pull-out hole 102 for attaching the cable pull-out metal fitting 12 is formed from the inside of the recess 11A to the outside of the strain generating body 10.

Further, the load cell 1A includes an attachment portion 13 for attaching an installation device (for example, a rod end). The mounting portion 13 is, for example, a rod end mounting portion which is a screw hole for screwing the rod end.

FIG. 3 is a diagram schematically showing an example of an actual usage mode of the load cell 1A. FIG. 3A is a front view of the load cell 1A, and FIG. 3B is a side view thereof.

A decorative plate 4 having a rectangular front surface and a U-shaped side surface is attached to the strain generating body 10 from either the upper or lower direction of the strain generating body 10. When the strain-causing body 10 is attached to the decorative plate 4, when viewed from the front, it is hidden behind the front surface 4B of the decorative plate 4 and cannot be seen, but when viewed from the side, the side surface of the strain-causing body 10 can be seen. At this time, the cable lead-out hole 102 and the cable C on the side surface of the strain generating body 10 are exposed to the outside.

A through hole (not shown) through which an installation tool (for example, a rod end 5A) is passed is formed on the upper surface of the decorative plate 4.

In this example, rod ends 9A and 9B are attached above and below the load cell 1A. In FIG. 3A, the upper rod end 5A is represented in a state of being rotated 90 degrees with respect to the lower rod end 5B.

The upper rod end 5A is screwed to the upper surface of the strain generating body 10 via a decorative plate 4 using a bolt (or nut) 6A or a nut (or flat washer) 7A. On the other hand, the lower rod end 5B is directly screwed to the lower surface of the strain generating body 10 using a bolt (or nut) 6B or a nut (or flat washer) 7B.

Pin insertion holes 50B for inserting pins 8A and 8B are formed in the upper and lower rod ends 5A and 5B. The pin insertion hole 50A corresponding to the upper pin 8A is hidden in the pin 8A, the retaining ring 200A, and the hanging metal fitting 9A in FIG. 3, and is not shown. These pins 8A and 8B are used to fix the hanging metal fittings 9A and 9B to the rod ends 5A and 5B.

The hanging metal fittings 9A and 9B have pin insertion holes 90A and 90B, and are fixed to the rod ends 5A and 5B by using the pins 8A and 8B. More specifically, in order to attach the hanging brackets 9A and 9B to the rod ends 5A and 5B, the pin insertion holes 90A and 90B of the hanging brackets 9A and 9B are inserted into the pin insertion holes 50A and 50B of the rod ends 5A and 5B, respectively. Face each other.

In that state, each of the pins 8A and 8B is inserted from either the left or right of the pin insertion holes 90A and 90B of the hanging metal fittings 9A and 9B, and the insertion is continued as it is, and the pin insertion holes 50A of the rod ends 5A and 5B are inserted. , 50B and the other pin insertion holes 90B, 90A. Then, the pins 8A and 8B are respectively connected to the hanging metal fittings 9A and 9B and the rod ends 5A and 5B by using the flat washers 200A and 200B and the retaining rings (here, E-shaped retaining rings) 300A and 300B, respectively. Fix it. In this way, the hanging metal fittings 9A and 9B are fixed to the rod ends 5A and 5B.

Although the upper flat washer 200A is not shown in FIG. 3 (A) and the lower flat washer 200B is not shown in FIG. 3 (B), in reality, they are opposed to the hanging metal fittings 9A and 9B, respectively. Similarly, it plays a role of fixing pins 8A and 8B.

The hanging metal fittings 9A and 9B have screw holes 90C at the uppermost portion and the lowermost portion for attaching the hanging metal fittings 9A and 9B to the fixing member or the movable member. As a method of installing this type of load cell 1A, for example, as shown in FIG. 3, one of the upper or lower hanging brackets 9A and 9B is fixed so as not to move, while the other hanging brackets 9B and 9A are fixed. There is a stationary type that can be moved in the vertical direction. In this stationary type, the tensile force due to the hanging metal fittings 9A and 9B on the movable side is detected by the load cell 1A.

Alternatively, although not shown, a method of mounting the load button (compression button) on the upper surface of the strain generating body 10 while directly mounting the surface (lower surface) facing the mounting surface of the load cell 1A on the mounting base. There is also. In this installation method, the force (compressive force) for pressing the compression button (load button) is detected by the load cell 1A.

As shown in FIGS. 1 and 2, the recesses 11A and 11B have the shape of an elliptical column having an open surface. The recesses 11A and the recesses 11B are formed symmetrically on the front and back with the boundary portion BO which is a part of the strain generating body 10 as a boundary, and the recesses 11A and 11B here have an opening and a back of the same width. The surface (here, the bottom surface) and the same shape having the same depth. The recess 11A includes a back surface 110A formed of the front surface of the boundary portion BO, and the recess 11B includes a back surface 110B formed of the back surface of the boundary portion BO. Strain gauges are arranged on the inner surfaces 110A and 110B. The recesses 11A and 11B are not necessarily symmetrical on the front and back sides, and may not be symmetrical as long as there is no problem in storing the components in the recesses 11A and 11B.

The recess 11A includes a wall surface 111A, and the recess 11B includes a wall surface 111B. Parts (in this case, gauge terminals, various resistors, and various cables) described later are arranged on the wall surfaces 111A and 111B. A cable is connected to the gauge terminal, and the cable is pulled out of the strain generating body 10 through the cable lead-out hole 102. To be precise, the cable is pulled out through the cable pull-out metal fitting 12 inserted and mounted in the cable pull-out hole 102.

The force detection circuit 14A as shown in FIG. 4 is formed by the strain gauges and parts housed in the recesses 11A and 11B. Here, the force detection circuit 14A is schematically represented, and is formed by connecting the series circuit of the resistors R2 and R3 and the series circuit of the resistors R1 and R4 to the bridge circuit of the strain gauges G1 to G4. ing.

In the force detection circuit 14, in addition to the resistors R1 to R4, a zero balance correction resistor wire, a temperature zero correction resistor wire, and an input resistance adjustment resistor are often provided. Resistances (temperature-sensitive resistances) R1 and R2 will be described in paragraph number "0996" described later. The resistors (sensitivity adjusting resistors) R3 and R4 will be described later in paragraph No. "097". Regarding the zero balance correction resistor wire (zero balance correction resistor wire R5 described later), the temperature zero correction resistor wire (temperature zero correction resistor wire R6 described later), and the input resistance adjustment resistor (input resistance adjustment resistor R7 described later), The paragraph numbers "0998" to "0100" will be described respectively.

The strain gauges G1 to G4 correspond to a compressive force and a tensile force, respectively, and these are combined to form a Wheatstone bridge. The resistors R1 to R4 are resistors for correcting the output voltage, and the strain gauges G1 to G4 correct the output voltage.

FIG. 5 is a diagram schematically showing recesses formed on the front side and the back side of the strain generating body 10, respectively, and for ease of explanation, the wall surfaces 111A and 111B which are deep portions are shown in a plane. There is. FIG. 5 (A) schematically shows the recess 11A on the front surface side of the strain generating body 10, and FIG. 5 (B) schematically shows the recess 11B on the back surface side. A gauge plate 19 having strain gauges G1 and G2 (first strain gauge) is attached to the inner surface 110A of the recess 11A on the front surface side by adhesive or other methods.

Further, a gauge plate 20 having strain gauges G3 and G4 (second strain gauge) is attached to the inner surface 110B of the recess 11B on the back surface side in the same manner.

Here, first of all, the connection wire and the leads of various resistors, which will be described later, are firmly connected to each metal terminal by soldering using flux. Further, a power supply line for supplying the drive power of the load cell 1A (power supply line C1 (plus side), power supply line (minus side) C2 described later) and an output line from which the output voltage from the load cell 1A is output (output line described later). The connection of the (plus side) C3 and the output line (minus side) C4) to the terminals of the gauge board is also connected by soldering using flux. As described above, in the reference load cell 1A, it is premised that the connection line, the lead of the resistor, and the power supply line and the output line are soldered to the terminals using flux.

The gauge terminals 15 and 16 are attached to the wall surface 111A of the recess 11A by adhesive or other methods corresponding to the gauge plate 19 on the front side. The gauge terminal 15 includes terminals 15A to 15C, and the gauge terminal 16 includes terminals 16A to 16E.

On the other hand, the gauge terminals 17 and 18 are attached to the wall surface 111B of the recess 11B by adhesion or other methods corresponding to the gauge plate 20 on the back side. The gauge terminal 17 includes terminals 17A to 17D, and the gauge terminal 18 includes terminals 18A to 18C.

The terminal 19A, which is one end of the strain gauge G1, is connected to the terminal 15B of the gauge terminal 15 through the connection wire L10. A terminal 19C, which is one end of the strain gauge G2, is connected to the terminal 15B through a connection line L11. In addition to one end of the strain gauges G1 and G2, the output line (plus side) C3 is connected to the terminal 15B through the connection line L12 and the terminal 16D of the gauge terminal 16. As a result, one ends of the strain gauges G1 and G2 are connected to each other, and the output line (plus side) C3 is connected to the connection point.

The terminals 20A and 20C, which are on the back side and are one ends of the strain gauges G3 and G4, are both connected to the terminal 17D of the gauge terminal 17 through the connection lines L13 and L14, respectively. Then, the terminal 17D is connected to the terminal 16B of the gauge terminal 16 through the connection line L1 through the hole 101 of the boundary portion BO. The output line (minus side) C4 is connected to the terminal 16B. As a result, one ends of the strain gauges G3 and G4 are connected to each other, and the output line (minus side) C4 is connected to the connection point.

A terminal 19B, which is the other side of the strain gauge G1 on the front side, is connected to the terminal 18C of the gauge terminal 18 by a connecting line L2 through a hole 101 of the boundary portion BO. Further, the terminal 20D, which is the other end of the strain gauge G4, is connected to the terminal 18C through the connection line L15. Then, one end of the temperature sensitive resistor R1 is connected to the terminal 18C. As a result, the other ends of the strain gauges G1 and G4 are connected to each other, and one end of the temperature sensitive resistor R1 is connected to the connection point.

The terminal 19D, which is the other end of the strain gauge G2, is connected to the terminal 17B of the gauge terminal 17 on the back surface side through the connection line L3 through the hole 101 of the boundary portion BO. Further, the terminal 17B is connected to the terminal 20B on the other side of the strain gauge G3 through the connection line L16. Then, one end of the temperature sensitive resistor R2 is connected to the terminal 17B. As a result, the other ends of the strain gauges G2 and G3 are connected to each other, and one end of the temperature sensitive resistor R2 is connected to the connection point.

Then, one end of the sensitivity adjusting resistor R3 is connected to the other end of the temperature sensing resistor R2 through the terminal 17A. The other end of the sensitivity adjustment resistor R3 is connected to the terminal 17C, and the terminal 17C is connected to the power supply line (minus side) C2 through the connection line L4 through the hole 101 of the boundary portion BO and the terminal 16A. There is.

On the other hand, one end of the sensitivity adjusting resistor R4 is connected to the other end of the temperature sensitive resistor R1 through the terminal 18B. The other end of the sensitivity adjustment resistor R4 is connected to the power supply line (plus side) C1 through the terminal 18A, the connection line L5 through the hole 101 of the boundary portion BO, and the terminal 16E.

The above-mentioned terminals, strain gauges, and terminals and strain gauges do not have conductivity without performing conduction processing using a connecting wire or the like. Therefore, the force detection circuit 14A of FIG. 4 can be configured by arranging and wiring the parts as described above. Therefore, by wiring as described above, the force detection circuit 14A in which the series circuit of the resistors R1 and R4 and the series circuit of the resistors R2 and R3 are connected in series to the Wheatstone bridge composed of the strain gauges G1 to G4 is provided. Can be formed.

In the above-mentioned load cell 1A, the two recesses 11A and 11B formed on the front surface side and the back surface side of the strain generating body 10 are divided into the above-mentioned elements necessary for force detection, that is, the strain gauge and the respective resistors. Since the gauge terminal is housed, for example, when the force detection circuit 14A is housed in a narrow area where the force is concentrated, it is not necessary to form a deep recess, so the load cell 1A should be made compact. Can be done.

Therefore, compared to the case where all the elements are stored in one recess, the depth of the recess can be reduced, so that the residual flux inside can be easily visually recognized, and the cleaning liquid can be easily applied to the residual flux with sufficient pressure. Become. This facilitates cleaning of the residual flux.

By the way, the present inventor has found that the load cell 1A has the following problems.

That is, the gauge terminals 15 to 18 are attached to the wall surfaces 111A and 111B of the recesses 11A and 11B. Since the recesses 11A and 11B are often formed in a narrow area where the force applied to the strain generating body 10 is likely to be concentrated, the size of the recesses is not so large. Therefore, it may be difficult for the cleaning liquid having a pressure and amount sufficient to clean the residual flux of the gauge terminals 15 to 18 to reach the residual flux.

In particular, the residual flux generated when the power supply lines C1 and C2 and the output lines C3 and C4 are attached to each of the terminals 16A to 16E of the gauge terminal 16 is covered with the power supply lines C1 and C2 and the output lines C3 and C4. In such a case, the cleaning liquid is less likely to reach the residual flux because it is obstructed by the power supply lines C1 and C2 and the output lines C3 and C4. In particular, in the case of the recess 11A having a narrow opening, it becomes difficult to move the power supply lines C1 and C2 and the output lines C3 and C4.

Therefore, the present inventor has invented the following load cell that facilitates cleaning of residual flux.

FIG. 6 is a cross-sectional view schematically showing a load cell according to an embodiment of the present invention. In the present embodiment, the load cell 1 has the same outer shape as the load cell 1A shown in FIG. FIG. 6 corresponds to a cross-sectional view taken along the line AA of the front view of FIG. 1 (B).

In FIG. 6, the components having the same reference numerals as the load cells 1A shown in FIGS. 1 to 5 represent the same components as the load cells 1A, and the components already described are omitted below for the sake of simplicity. do.

In the load cell 1 according to the embodiment of the present invention, the front side and the back side of the strain generating body 10 have openings and back surfaces of the same width and recesses 11A and 11B of the same shape having the same depth. However, they are formed symmetrically on the front and back sides of the boundary portion B0.

As long as the necessary elements can be compactly stored in the recesses 11A and 11B, the recesses 11A and 11B do not necessarily have the same shape with the same width of the opening and the back surface and the same depth. Further, it does not have to be an elliptical pillar, and the shapes of the recesses 11A and 11B are merely design matters of those skilled in the art.

In this load cell 1, no component including a gauge terminal is attached to each of the wall surfaces 111A and 111B of the recesses 11A and 11B.

Instead, in the recess 11A on the front side, strain gauges G1 and G2 corresponding to compressive force and tensile force, butyl rubber (protective member) 40A, and component substrate 21 are stored in this order from the back surface 110A to the surface S of the recess 11A. Has been done. Further, from the back surface 110B to the surface S of the recess 11B on the back surface side, strain gauges G3 and G4 corresponding to compressive force and tensile force, butyl rubber (protective member) 40B, and component substrate 22 are stored in the recess 11B in this order. Has been done.

The butyl rubbers 40A and 40B each play a role of protecting the strain gauges G1 to G4 or a pedestal for mounting the component substrates 21 and 22 on the strain gauges G1 to G4.

In this load cell 1, four strain gauges G1 to G4 constitute a Wheatstone bridge. If the four strain gauges G1 to G4 are collectively stored in one recess, the deformation of the strain gauges G1 to G4 may be distorted. In the load cell 1 according to the embodiment of the present invention, the strain gauges G1 and G2 are stored in the recesses 11A on the front side, and the strain gauges G3 and G4 are stored in the recesses 11B on the back side. It is possible to suppress the possibility that the deformation of G4 becomes distorted.

Further, since the recess for storing the strain gauge or the like is usually installed in a narrow part where the force is concentrated, all the elements including the strain gauges G1 to G4 are stored in the recess in the narrow part. The work efficiency deteriorates.

However, in the load cell 1 according to the embodiment of the present invention, since the above-mentioned elements necessary for force detection are stored in the two recesses 11A and 11B, the load cell 1 is formed in a narrow area where the force is concentrated. The force detection circuit 14 can be housed in a recess, which is often the case, and the load cell 1 can be made compact.

Further, although the cable C is usually led out from the component board in the recess, the cable C usually has a thickness and the maneuverability in the recess is poor. Therefore, if all the components including the cable C are stored in one recess, it becomes difficult for the cable C to be routed in the recess.

Therefore, in the load cell 1 according to the present invention, the components are divided into two recesses and stored, and the wiring in the recess 11A on the front surface side is reduced as much as possible as compared with the recess 11B on the back surface side, so that the recess 11A The cable C is stored on the side. As a result, the maneuverability of the cable C in the recess 11A is improved, and the cleanability of the residual flux hidden in the cable C is improved.

The component substrates 21 and 22 are housed in the recesses 11A and 11B, respectively, on the strain gauges G1 and G2 and the strain gauges G3 and G4 via the butyl rubbers 40A and 40B, respectively.

More specifically, as shown in FIG. 6, strain gauges G1 and G2, gauge terminals 24 and 25, butyl rubber 40A, and component substrate 21 are placed in this order from the back surface 110A of the recesses 11A and 11B toward the surface S. NS. Further, on the back surface side, strain gauges G3 and G4, gauge terminals 26 and 27, butyl rubber 40B, and component substrate 22 are placed in this order.

For example, an input resistance adjusting resistor R7, which is a metal film resistor, is connected to the component substrate 21 on the recess 11A side. For example, sensitivity adjusting resistors R3 and R4, which are metal film resistors, are connected to the component substrate 22 on the recess 11B side.

The gauge terminals 24 and 25 are attached to the inner surface 111A of the recess 11A on the front side by an adhesive or other method so as to line up with the strain gauges G1 and G2 in parallel with the surface of the recess 11A. Of the gauge terminals 24 and 25, in the figure, the temperature sensitive resistor R1 is connected to the gauge terminal 24.

Further, the gauge terminals 26 and 27 are attached to the inner surface of the recess 11B on the back side by an adhesive or other method so as to line up with the strain gauges G3 and G4 in parallel with the surface of the recess 11B. Of the gauge terminals 26 and 27, the temperature sensitive resistor R2 is also connected to the gauge terminal 26.

In this way, the gauge terminals 24 to 27 are attached to the inner surface of the recess 11A on the front side so as to line up with the strain gauges G1 to G4 in parallel with the surface S of the recesses 11A and 11B. As a result, when the component substrates 21 and 22 are moved, if there is residual flux in the gauge terminals 24 to 27 and the strain gauges G1 to G4, the residual flux is exposed on the concave surface S. This makes it easier to clean the residual flux of the gauge terminals 24 to 27 and the strain gauges G1 to G4.

A cable lead-out hole 102 for mounting the cable pull-out metal fitting 12 is formed from the inside of the recess 11A of the strain-causing body 10 to the outside of the strain-causing body 10, and the cable pull-out metal fitting 12 is formed in the cable lead-out hole 102. It is inserted and attached. The cable pull-out metal fitting 12 has a hollow shape, and the cable C connected to the component board 21 is pulled out.

Further, after all the necessary elements are stored in the recesses 11A and 11B, the margins are filled with silicone 30, which is one of the waterproof resins. If the cable pull-out metal fittings 12 and the cable pull-out holes 102 are also filled with the waterproof resin in addition to the recesses 11A and 11B, the waterproof function of the load cell 1 can be further improved.

FIG. 7 is a diagram showing an example of a force detection circuit. The force detection circuit 14 has the same basic structure as the force detection circuit 14A described above in FIG. The force detection circuit 14 includes the Wheatstone bridge circuit using strain gauges G1 to G4, resistors R1, R2, R3, and R4, as well as zero balance correction resistor wire R5, temperature zero correction resistor wire R6, and input resistance adjustment. It has a resistor R7.

In the force detection circuit 14, the series circuit of the resistors R2 and R3 and the series circuit of the resistors R1 and R4 are connected to the bridge circuit of the strain gauges G1 to G4. Further, in the force detection circuit 14, a temperature zero correction resistance wire R6 is connected to one end of each of the strain gauges G1 and G4. Further, a zero balance correction resistance wire R5 is connected to one end of each of the strain gauges G2 and G3.

Further, the power supply line (plus side) C1 is derived from the series circuit of the resistors R1 and R4, and the output line (minus side) C2 is derived from the series circuit of the resistors R2 and R3. An input resistance adjusting resistor R7 is connected between the power supply line (plus side) C1 and the power supply line (minus side) C2.

The resistors R1 and R2 are temperature-sensitive resistors, and the resistance value changes in response to a change in the ambient temperature to correct the output voltage from the bridge circuits of the strain gauges G1 to G4.

The resistors R3 and R4 are sensitivity adjusting resistors, and have a function of adjusting the output voltage of the load cell 1 in order to keep the rated output of the load cell 1 within the specifications. If the output voltage of the load cell 1 is large, measures such as increasing the sensitivity adjustment resistance are taken.

The zero balance correction resistance line R5 corrects the output voltage of the strain gauges G1 to G4 so that the output voltage becomes a constant near zero when no force is applied to the strain gauges G1 to G4.

When the strain generating body 10 and the strain gauges G1 to G4) expand or contract due to a change in the ambient temperature, the temperature zero correction resistance line R6 causes an error (heat output) in the detection voltage of the force detection circuit 14, so this is near zero. Correct so that it approaches.

The input resistance adjusting resistor R7 is a voltage value input to the power supply lines C1 and C2 according to the resistance value in order to make the amount of current flowing through each load cell 1 uniform when the scale is configured by the plurality of load cells 1. To adjust.

By connecting these resistors R1 to R7 to the bridge circuit of the strain gauges G1 to G4, the output voltage is changed in parallel with the change in the resistance value of any of the strain gauges G1 to G4. By doing so, accurate force detection is possible.

FIG. 8 is a diagram schematically showing recesses formed on the front side and the back side of the strain generating body 10 of the load cell 1 according to the embodiment of the present invention. In FIG. 7, for the sake of simplicity, the wall surfaces 111A and 111B, which are the deep portions, are shown in a plane.

As shown in FIG. 8A, a gauge plate 2 having strain gauges G1 and G2, each of which corresponds to a compressive force and a tensile force, is attached to the inner surface 110A of the recess 11A on the front side by adhesion or other methods. There is. Further, as shown in FIG. 8B, a gauge plate 3 having strain gauges G3 and G4, each of which corresponds to a compressive force and a tensile force, is attached to the inner surface 110B of the recess 11B on the back side by adhesion or other methods. Has been done.

On the front side, the gauge terminals 24 and 25 are not attached to the wall surface 111A, but are aligned with the gauge plates 2 (strain gauges G1 and G2) on the back surface 110A in parallel with the surface S (see FIG. 6). It is attached by gluing or other methods. In this example, the gauge terminals 24 and 25 are arranged on the same plane as the gauge plate 2.

Further, on the back side (see FIG. 6), the gauge terminals 26 and 27 are not attached to the wall surface 111B but are attached to the back surface 110B in parallel with the surface S so as to be aligned with the gauge plate 3, as in the front side. ing. In this example, the gauge terminals 26 and 27 are arranged on the same plane as the gauge plate 3.

In the load cell 1 of the present embodiment, the gauge terminals 24 and 25 are arranged so as to be aligned with the strain gauges G1 and G2 in parallel with the surface S, but the gauge terminals 24 and 25 can be connected to other components in the recess 11A. If there is no problem in storage, it is not always necessary to arrange them so as to be parallel to the surface S. This also applies to the gauge terminals 26 and 27 on the back surface side.

As shown in FIG. 8A, patterns P1 to P6 are formed on the component substrate 21 in the recess 11A by etching or other methods. On the right side of the component substrate 21, for example, the patterns P1 and P2 are formed so as to sandwich the pattern P6. On the left side, on the other hand, patterns P3 to P5 are formed so as to be adjacent to each other in the left-right direction.

Here, first of all, the connection wire and the leads of various resistors, which will be described later, are firmly connected to the metal terminals and the pattern on the component substrate by soldering using flux. Further, the connection of the power supply line and the output line to the pattern on the component board is also connected by soldering using flux. Further, as will be described later, in the component substrates 21 and 22, the component mounting surfaces (surfaces on which resistors R3 to R7, power supply lines C1 and C2, output lines C3 and C4 exist) are on the surface S side of the recesses 11A and 11B. It is stored in the recesses 11A and 11B so as to face it.

As described above, in the load cell 1 according to the embodiment of the present invention, the connection line, the lead of the resistor, and the power supply line and the output line are soldered to the terminal and the pattern on the component board using flux. It is assumed that it will be done.

In the component board 21, each of the patterns P3 to P6 has a power supply line (plus side) C1, a power supply line (minus side) C2, an output line (minus side) C4, and an output line (plus side) C3, respectively. It is connected.

A temperature zero correction resistor wire R6 is connected between the patterns P1 and P6 and between the patterns P2 and P6, respectively. A total of five connecting lines are derived from the component substrate 21, and through holes are formed in each of the patterns P3 to P6.

On the other hand, as shown in FIG. 8B, patterns P7 to P13 are formed on the component substrate 22 in the recess 11B by etching or other methods. In the component substrate 22, the patterns P7 and P8 are formed at the uppermost portion, and the pattern P9 is formed so as to be directly below both of them. Patterns P10 and P11 are formed side by side in the horizontal direction on the lower side of the component substrate, and patterns P12 and P13 are formed side by side in the horizontal direction directly below them.

A zero balance correction resistance wire R5 is connected between the patterns P7 and P9 and between the patterns P8 and P9, respectively. A total of seven connecting lines are derived from the component substrate 22, and through holes are formed in each of the patterns P10 to P13.

The gauge plate 2 on the front side includes a terminal 2A which is one end of the strain gauge G1, a terminal 2C which is one end of the strain gauge G2, and a terminal 2B which also serves as the other end of the strain gauges G1 and G2. Further, the gauge plate 3 on the back side includes a terminal 3A which is one end of the strain gauge G3, a terminal 3C which is one end of the strain gauge G4, and a terminal 3B which also serves as the other end of the strain gauges G3 and G4.

The terminal 2A, which is one end of the strain gauge G1, is connected to the terminal 25A of the gauge terminal 25. The terminal 25A is connected to the pattern P1 of the component substrate 21 through the connection line L20, and one end of the temperature zero correction resistance wire R6 is connected to the pattern P1.

On the other hand, the terminal 3C, which is one end of the strain gauge G4 on the back side, is connected to the terminal 27B of the gauge terminal 27. The terminal 27B is connected to the pattern P2 of the component substrate 22 to which one end of another temperature zero correction resistor wire R6 is connected through the connection line L30 through the hole 101 of the boundary portion BO. In this way, one end of the temperature zero correction resistance wire R6 is connected to one end of each of the strain gauges G1 and G4 provided on the front and back sides, respectively.

Further, the terminal 2C, which is one end of the strain gauge G2, is connected to the terminal 25B of the gauge terminal 25. The terminal 25B is connected to the pattern P7 to which one end of the zero balance correction resistance wire R5 is connected through the connecting wire L31 through the hole 101 of the boundary portion BO.

The terminal 3A, which is one end of the strain gauge G3 on the back surface side, is connected to the terminal 27A of the gauge terminal 27. The terminal 27A is connected to the pattern P8 to which one end of the zero balance correction resistance wire R5 is connected through the connecting wire L21.

In this way, one end of the zero balance correction resistor wire R5 is connected to one end of each of the strain gauges G2 and G3 provided on the front and back sides.

The other ends of the two zero balance correction resistor wires R5 are connected to the pattern P9 directly below both the patterns P7 and P8, respectively. The pattern P9 is connected to the pattern P5 to which the output line (minus side) C4 is connected through the connecting line L32 through the hole 101 of the boundary portion BO. As a result, the other ends of the two zero balance correction resistor wires R5 are connected to the output wire (minus side) C4, respectively.

The terminal 2B that also serves as the other end of the strain gauges G1 and G2 on the front side is connected to the terminal 24B of the gauge terminal 24. A temperature sensitive resistor R1 is connected between the terminals 24A and 24B of the gauge terminal 24.

The terminal 24A to which the other end of the temperature sensitive resistor R1 is connected is connected to the pattern P12 on the back surface through the connection line L33 through the hole 101 of the boundary portion BO. A sensitivity adjustment resistor R4 is connected between the patterns P12 and P13.

The pattern P13 to which one end of the sensitivity adjusting resistor R4 is connected is connected to the pattern P3 of the component substrate 21 on the front side through the connection line L34 through the hole 101 of the boundary portion BO. A power supply line (plus side) C1 is connected to the pattern P3.

As a result, a series circuit of the temperature sensitive resistor R1 and the sensitivity adjustment resistor R4 is connected to the connection between the other ends of the strain gauges G1 and G2 on the front side, and the power supply line (plus side) C1 is further connected to the series circuit. Connecting.

The terminal 3B, which goes around the back surface and is a connection portion between the other ends of the strain gauges G3 and G4, is connected to the terminal 26B of the gauge terminal 26. A temperature sensitive resistor R2 is connected between the terminals 26A and 26B of the gauge terminal 26.

The terminal 26A to which the other end of the temperature sensitive resistor R2 is connected is connected to the pattern P11 through the connection line L22. A sensitivity adjustment resistor R3 is connected between the patterns P10 and P11.

The pattern P10 to which the other end of the sensitivity adjusting resistor R3 is connected is connected to the pattern P4 of the component substrate 21 on the front side through the connection line L35 through the hole 101 of the boundary portion BO. A power supply line (minus side) C2 is connected to the pattern P4.

As a result, a series circuit of the temperature sensitive resistor R2 and the sensitivity adjustment resistor R3 is connected to the connection between the other ends of the strain gauges G3 and G4 on the back side, and the power supply line (minus side) C2 is further connected to the series circuit. Connecting.

The input resistance adjusting resistor R7 is connected between the through holes of the patterns P3 and P4 of the component substrate 21. Since one end of the power supply line (plus side) C1 is connected to the pattern P3 and one end of the power supply line (minus side) C2 is connected to the pattern P4, an input resistor is connected between the two power supply lines C1 and C2. The adjustment resistor R7 can be connected.

Conductivity between the above-mentioned terminals, between patterns, between terminals and patterns, and between gauge plates and other parts (for example, terminals, patterns, other gauge plates) without performing continuity processing using connecting wires or the like. I don't have it. Therefore, the force detection circuit 14 of FIG. 7 can be configured by arranging and wiring the parts as described above.

As can be seen from FIG. 8, the number of wirings on the component board 21 on the front side is a total of five connecting lines L20, L30, L32, L34, and L35. On the other hand, the number of wirings on the component substrate 22 on the back side is a total of seven connecting lines L31 to L35, L21, and L22.

As described above, since the number of wires on the front side component board 21 side is smaller than that on the back side component board 22 side, there is a margin of space for routing the cable C in the recess 11A on the front side. Therefore, the power supply lines C1 and C2 and the output lines C3 and C4 can be easily stored in the recess 11A on the front side. This effect becomes more remarkable when the number of parts (for example, resistors) of the component board 21 is smaller than the number of parts of the component board 22.

The power supply lines C1, C2, output lines C3, and C4 are collectively drawn out as a cable C into the cable lead-out hole 102 through the hole 100 formed in the wall surface 111A, and the strain-causing body 10 is pulled out through the cable pull-out metal fitting 12 mounted therein. It is pulled out to the outside.

FIG. 9 is a diagram showing a configuration example of a double-sided tape used for fixing each of the component substrates 21 and 22 in the recesses 11A and 11B.

The double-sided tape (fixing member) 29A shown in FIG. 9A is created for the recess 11A on the surface, and the component substrate 21 is attached to the strain gauge 2 (see FIG. 12) on the back surface of the recess 11A. It is used to fix it. On the other hand, the double-sided tape (fixing member) 29B shown in FIG. 9B is created for the recess 11B on the back surface, and the component substrate 22 is attached to the strain gauge 3 on the back surface of the recess 11B (see FIG. 12). ) Is used to fix it.

Since the double-sided tapes 29A and 29B fix the component substrate 21 and the butyl rubber 40A as shown in FIG. 12, they are substantially the same size as the butyl rubber 40A or slightly smaller than the butyl rubber 40A. However, in FIGS. 9A and 9B, in order to make it easier to understand the structures of the double-sided tapes 29A and 29B, the component substrates 21 and 22 are enlarged to almost the same size.

The double-sided tape 29A shown in FIG. 9A is formed with protective holes 290A corresponding to a total of six through holes formed in the patterns P3 to P6 of the component substrate 21. The lead wires of the power supply lines C1, C2, the output lines C3, C4, and the input resistance adjusting resistor R7, which protrude from the through holes, pass through these protective holes 290A.

On the other hand, the double-sided table 29B shown in FIG. 9B has a plurality of protective holes 290B formed. Of the lead wires inserted into the through holes of the sensitivity adjusting resistor R4 between the patterns P10 and P10 of the component substrate 22 and the sensitivity adjusting resistor R3 between the patterns P12 and P12 in these protective holes 290B, The part that protrudes from the through hole passes through.

The component boards 21 and 22 are made of butyl rubber 40A so that the component mounting surfaces, which are the surfaces on which the resistors R3 to R7, the power supply lines C1 and C2, and the output lines C3 and C4 are located, face the surfaces of the recesses 11A and 11B, respectively. It is placed on 40B (see FIG. 6). In this example, the component substrates 21 and 22 are shown in FIG. 8 when the recesses 11A and 11B are in the directions shown in FIG. 8 (directions such that the temperature sensitive resistors R1 and R2 are located on the left side of the paper surface). Place it on the butyl rubbers 40A and 40B with the direction facing.

At this time, each of the double-sided tapes 29A and 29B shown in FIG. 9 is attached to the component substrates 21 and 22 in the direction opposite to the vertical direction of the component substrates 21 and 22 shown in FIG. Then, the protective holes 290A and 290B of the double-sided tapes 29A and 29B and the through holes of the component substrates 21 and 22 are in a positional relationship facing each other.

As described above, since the component substrates 21 and 22 are mounted on the butyl rubbers 40A and 40B so that the component mounting surfaces face the front surface, the back surfaces (component non-mounting surfaces) of the component substrates 21 and 22 are the butyl rubber 40A. Contact with 40B. Therefore, a part of the lead wires protruding from the through holes of the component substrates 21 and 22 does not hit the strain gauges G1 to G4 because the butyl rubbers 40A and 40B (see FIG. 6) serve as cushions.

As described above, the protective holes 290A and 290B of the double-sided tapes 29A and 29B are attached so as to face the through holes. Therefore, the respective protective holes 290A and 290B cooperate with the butyl rubbers 40A and 40B to protect a part of the lead wire protruding from the through hole from hitting the strain gauges G1 to G4. The depth (depth) of the protective holes 290A and 290B is set so that a part of the lead wire stuck in the butyl rubbers 40A and 40B does not hit the strain gauges G1 to G4. ing.

For example, the depth of the protective holes 290A and 290B is the distance between the tip of a part of the lead wire stuck in the butyl rubbers 40A and 40B and the contact surface between the butyl rubbers 40A and 40B and the component substrates 21 and 22. It is preferable that the length is added with a certain margin. The larger this margin is, the less likely it is that even if the tip of the lead wire protrudes from the butyl rubbers 40A and 40B, the strain gauges G1 to G4 and the gauge terminals alongside them will be damaged.

10 to 12 are views for explaining an example of a procedure for storing components in the load cell 1 according to the present embodiment.

10 (A) is a front view, FIG. 10 (B) is a cross-sectional view taken along the line AA of FIG. 10 (A), FIG. 10 (C) is also a front view, and FIG. 10 (D) is FIG. 10 (C). It is a cross-sectional view taken along the line AA. 11 is also a front view, and FIG. 12 is a cross-sectional view taken along the line AA of FIG.

It should be noted that the cross-sectional views taken along the line AA in FIGS. 10 (B), 10 (D), and 12 have different dimensions from the corresponding front views, but this is a component. In order to make it easy to understand the stored state of the above, in reality, the dimensions of each of the cross-sectional views taken along the line AA and the corresponding front view are the same.

First, as shown in FIGS. 10A and 10B, recesses 11A and 11B are formed on the front and back surfaces of the strain generating body 10 leaving the boundary portion BO. In this state, strain gauges G1 to G4 and gauge terminals 24 to 27 are attached to the inner surfaces 110A and 110B of the recesses 11A and 11B so as to be aligned parallel to the surface of the recess. Further, the temperature sensitive resistors R1 and R2 are connected to the gauge terminals 24 and 26 on the front and back, respectively.

The temperature sensitive resistors R1 and R2 are installed so as to be located very close to the recessed inner surfaces 110A and 110B. As a result, it is possible to accurately know the temperature change of the inner surface of the recess, which is often the force concentration portion, and to accurately correct the fluctuation of the force detection result due to the temperature.

Next, as shown in FIGS. 10C and 10D, butyl rubbers 40A and 40B are installed on the strain gauges G1 to G4, respectively. Since the butyl rubbers 40A and 40B have sufficient adhesiveness, the strain gauges G1 to G4 are appropriately fixed to the butyl rubbers 40A and 40B by the adhesiveness.

In this example, the double-sided tapes 29A and 29B are one size smaller than the butyl rubbers 40A and 40B, but are not limited to this. The double-sided tape 29A is attached to the butyl rubber 40A from the surface side of the recess 11A in the direction shown in the drawing with the strain generating body 10 facing the drawing surface of FIG. 10 (D) toward the front side. On the other hand, the double-sided tape 29B is attached to the butyl rubber 40B from the surface side of the recess 11B with the strain generating body 10 facing the back side opposite to the front side in the direction shown in the drawing. Attached.

Next, as shown in FIGS. 11 and 12, in the recess 11A on the front side, the necessary parts, here, the temperature zero correction resistor wire R6 and the component board 21 to which the input resistance adjustment resistor R7 is connected are connected. The parts are placed on the butyl rubber 40A so that the component mounting surfaces (resistors R6, R7, power supply lines C1, C2, output lines C3, and C4 are located) face the surface side of the recess 11A. The butyl rubber 40A and the component substrate 21 are fixed with double-sided tape 29A.

Similarly, on the back side, the necessary parts, here, the component substrate 22 to which the sensitivity adjustment resistors R3 and R4 and the zero balance correction resistor wire R5 are connected, are located in the recess 11B on the component mounting surface (resistors R3 to R7). Place it on the butyl rubber 40B so that the surface) faces the surface side of the recess 11B. The butyl rubber 40B and the component substrate 22 are fixed with double-sided tape 29B.

As described above, the double-sided tapes 29A and 29B are formed with holes corresponding to the through holes of the component substrates 21 and 22, and the leads inserted into the through holes pass through the double-sided tapes 29A and 29B. The hole portion protects the strain gauges G1 to G4 and the gauge terminals arranged in the strain gauges G1 to G4 from the portion where the lead wire protrudes from the through hole.

Finally, power supply lines C1, C2, output lines C3, and C4 are connected to each of the patterns P3 to P6 of the component board 21 on the front side, and these are grouped together in the form of a cable C to form a cable lead-out hole of the strain generating body 10. It is pulled out to the outside of the strain generating body 10 through the cable pull-out metal fitting 12 attached to the 102.

As described above, according to the load cell 1 according to the present embodiment, no parts are installed on the wall surfaces 111A and 111B of the recesses 11A and 11B. Then, component substrates 21 and 22, which are likely to have residual flux due to solder, are arranged on the surface side of the recesses 11A and 11B.

As a result, the residual flux due to soldering is exposed on the surface in the recesses 11A and 11B, so that there is an advantage that the residual flux can be easily cleaned. In particular, when the residual flux is covered by the power supply lines C1, C2, the output lines C3, C4 and the cable C, each of them is superficially exposed in the recesses 11A and 11B, so each of them is moved by a finger. It is easy to clean the residual flux underneath.

Further, the work efficiency is improved by placing the component board to which the component is connected in a plane in the recess rather than mounting the gauge terminal on the wall surface of the recess.

In addition, the recess is divided into two parts on the front and back, and the necessary parts, that is, the strain gauge, each resistor, the connection wire, and the gauge terminal are stored in two groups, so that the size and depth of the recess are stored. It doesn't need much. Therefore, the cleaning liquid is likely to be applied to the entire recess with a strong pressure, and the cleaning efficiency of the residual flux is improved.

As can be seen from FIG. 6, the depth (depth) of the central portion (see FIG. 1B) including the recesses 11A and 11B is determined by the two recesses 11A and 11B and their boundary BO. Therefore, if not only the recesses 11A and 11B but also the boundary portion BO is thinned, the depth of the central portion including the recesses 11A and 11B (see FIG. 1B) is inevitably shallow.

If the central portion (see FIG. 1 (B)) is made shallow, the upper and lower portions (see FIG. 1 (B)) including the mounting portion 13 to which the rod end should be attached in order to ensure smooth distortion of the strain generating body 10. Also needs to be thin.

However, if the upper and lower portions (see FIG. 1B) are made too shallow, the rod ends are attached to the upper and lower portions, so that the load cell 1 may have insufficient strength. Therefore, it should be added that the depths of the recesses 11A and 11B should be taken into consideration in consideration of the strength of the upper and lower portions (FIG. 1B) to which the rod end should be attached.

Further, since the cable C is thick and has poor maneuverability in the recess, if all the elements are stored in one recess, it becomes difficult for the cable C to be routed in the recess. However, in the load cell 1 according to the present invention, the wiring in the recess 11A on the front surface of the strain generating body 10 is reduced as much as possible as compared with the recess 11B on the back surface, and the cable C is arranged there.

For example, according to FIG. 8, the number of wires in the component board 21 of the recess 11A is 5, whereas the number of wires in the component board 22 of the recess 11B is 7, and the number of wires in the component board 21 is larger. few.

Since the number of wires on the recess 11A side is smaller than that on the recess 11B side, the wiring efficiency of the power supply lines C1, C2, output lines C3, C4 and cable C at the time of creating the load cell 1 is improved, and the residual flux is cleaned. Sometimes it becomes easier to move each of these with your finger.

Further, since the holes 101 connecting the front and back recesses 11A and 11B are formed, the parts in the recess 11A and the parts in the recess 11B can be wired through the holes 101, so that the surface area is not so large. Even if a large recess is not provided, the necessary parts can be stored separately in the recesses 11A and 11B, and if necessary, the front and back parts can be connected to each other by wiring to form a compact recess, which in turn can be achieved. , A compact strain-causing body 10 can be formed.

The inner surfaces of the recesses 11A and 11B become bottom surfaces when the surface S of the strain generating body 10 is placed upward, and become a partition surface when the surface S of the strain generating body 10 is placed sideways. In this way, each back surface is called differently depending on how the strain generating body 10 is placed.

Further, the pattern shape of the component substrates 21 and 22 is not limited to the above, and is adapted to the storage mode of various components such as resistors R1 to R7 in the recesses 11A and 11B, power supply lines C1 and C2, and output lines C3 and C4. It can be changed as appropriate. Further, the pattern in which the positions of the through holes of the component substrates 21 and 22 are formed can be appropriately changed according to the mode of storing various components in the recesses. In this case, the double-sided tapes 29A and 29B have a structure in which holes having a length corresponding to the positions of the through holes and having a length that can appropriately protect the strain gauges G1 to G4 from the portion where the lead wire can protrude from the through holes are formed. do.

In the present embodiment, an S-shaped load cell is illustrated as an example of the load cell, but the present invention is not limited to this example, and all load cells of the type in which the strain gauge and other necessary parts are housed in the recess. In addition, the present invention is applicable.

From the above description, many improvements and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed as an example only and is provided for the purpose of teaching those skilled in the art the best aspects of carrying out the present invention. The details of its structure and / or function can be substantially changed without departing from the spirit of the present invention.

The present invention is useful as a load cell in which it is easy to clean the residual flux inside the recess.

1, 1A S-shaped load cell 4 Veneer 5A, 5B Rod end 8A, 8B Pin 9A, 9B Hanging bracket 10 Strain gauge 11A First recess 11B Second recess 12 Cable pull-out bracket 102 Cable pull-out hole 30 Silicone BO boundary 101 hole 14, 14A force detection circuit 21 1st component board 22 2nd component board 29A, 29B Double-sided tape 290A, 290B Protective hole 40A, 40B Butyl rubber 110A, 110B Recessed surface 111A, 111B Each wall surface G1, G2 1st strain gauge G3, G4 2nd strain gauge 24-27 Gauge terminals R1, R2 Temperature sensitive resistance R3, R4 Sensitivity adjustment resistance R5 Zero balance correction resistance line R6 Temperature zero correction resistance line R7 Input resistance adjustment resistor L1 to L5, L10 to L16, L20 to L22, L30 to L35 Connection line C1 Power supply line (plus side)
C2 power line (minus side)
C3 output line (plus side)
C4 output line (minus side)
C cable

Claims (9)

Equipped with a strain-causing body with recesses formed
In the direction from the inner surface of the recess to the surface of the recess, a strain gauge and a component substrate on which components for forming a force detection circuit using the strain gauge are mounted are housed in this order, while the above-mentioned The above parts are not attached to the wall surface of the recess.
As the recess, the first recess on the front side of the strain-causing body and the second recess on the back surface side of the strain-causing body are formed separately.
At least, the load cell is a load cell in which the component boards are separately distributed and stored in the first and second recesses as the first and second component boards. Connection lines are derived from the first and second component boards.
The number of the connecting lines of the first component board is less than the number of the connecting lines of the second component board.
The load cell according to claim 1, wherein any of a power supply line, an output line, and a cable derived from the first component board is housed in the first recess. The load cell according to any one of claims 1 or 2, wherein the gauge terminal used as the connection terminal of the strain gauge is arranged under the component substrate. The load cell according to claim 3, wherein the gauge terminal is arranged side by side with the strain gauge in a direction parallel to the surface of the recess. The load cell according to any one of claims 1 to 4, wherein the component is attached to the surface side of the recess of the component substrate. The load cell according to any one of claims 1 to 5, wherein a protective member for the strain gauge is interposed between the strain gauge and the component substrate. Through holes are formed in the component substrate, and the through holes are formed.
The protective member and the component substrate are fixed by a fixing member.
The fixing member is formed with a protective hole having a depth for protecting the strain gauge from a portion where a lead wire inserted into the through hole can protrude from the through hole, corresponding to the through hole. The load cell according to claim 6. Equipped with a strain-causing body with recesses formed
While the strain gauge and the component board on which the component for forming the force detection circuit using the strain gauge is mounted are sequentially housed in the direction from the inner surface of the recess to the surface of the recess,
The component is not attached to the wall surface of the recess,
A protective member for the strain gauge is interposed between the strain gauge and the component substrate.
Further, through holes are formed in the component substrate, and the through holes are formed.
The protective member and the component substrate are fixed by a fixing member.
The fixing member is formed with a protective hole having a depth for protecting the strain gauge from a portion where a lead wire inserted into the through hole can protrude from the through hole, corresponding to the through hole. Load cell. As the recess, a first recess on the surface of the strain-causing body and a second recess on the back surface of the strain-causing body are formed separately.
The load cell according to claim 9, wherein at least the strain gauges are separately distributed and stored in the first and second recesses as the first and second strain gauges.

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