JPH0454425Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The disclosed technology belongs to the technical field of the structure of a strain body made of aluminum or the like of a load cell used in a weight detection section of an electronic scale, a combination weighing device, etc.

<Summary of the gist> The invention of this application is that a notch is recessed in the strain detection part of a strain-generating body made of aluminum or the like of a load cell used in an electronic scale, etc. This invention relates to a strain body structure in which a strain gauge is attached and a conductive wire connecting the strain gauge to a Wheatstone bridge is disposed in the strain body. The strain gauge, the Wheatstone bridge circuit, its conductive wires, and all electrical components such as the compensation resistor are attached so that they are inside the surface level of the detection part, and the coating agent is applied. This invention relates to a strain-generating structure of a load cell that is filled.

<Prior art> As is well known, electronic scales with digital display have come to be widely used as product weight detection devices attached to registers in supermarkets, etc., instead of conventional spring scales. Load cells, which are widely used in load detectors and the like, have come to be used as the weight detection part because of their ability to convert the load into an electrical signal.

Therefore, load cells have been widely used in various industries for weighing, etc., and mass production has become widespread.

As shown in FIG. 3, in the load cell 1, a strain-generating body 3 made of aluminum or the like and having a substantially rectangular side surface is fixed in a cantilever manner to a support 2 provided on the device frame. A sensing part is formed on the side,
Strain gauges 6, 6... that convert the strain due to load into electrical signals are attached to the outer surfaces of the strain detection parts 5, 5... on the upper and lower surfaces 4 with adhesive, etc., and the cables are inserted into the support body 2. They are connected by conductive wires 8, 8, . . . drawn out from a cable (not shown) from the common hole 7 to form a Wheatstone bridge.

After forming the strain-generating body 3, the strain detection units 5, 5...
Attaching the strain gauges 6, 6... to the outer surface of the wire and connecting the conductive wires 8, 8... is an extremely delicate work, and at the same time, welding and connecting work in narrow areas requires extremely skill. It was hot.

<Problems that the invention attempts to solve> And these days, to deal with these complicated tasks,
A technique has been developed in which a printed circuit board or the like having conductive wires printed thereon, such as an FPC (flexible printed circuit), is attached together with the strain gauges 6, 6 to the side surfaces of the strain detecting sections 5, 5.

However, no matter which pasting means was used, the strain gauges 6 and the like were pasted on the outside of the strain detection parts 5, 5, at substantially the same level as the outer surfaces thereof.

By the way, the load cell 1 is attached to an electronic scale, a combination weighing device, etc., and various objects to be weighed, such as products, are handled and passed upstream around the mechanical part of the load cell 1. Therefore, the liquid components of the products are likely to adhere, and the entire device may be damaged. , and the main mechanical parts need to be cleaned regularly or irregularly.
Cleaning liquid such as water is often flowed from above, and therefore there is a potential that water may seep into the load cell 1 of the load detection section.

In response to this, mechanisms have been developed in which the load cell is housed in a watertight box-type casing to make it waterproof and moisture-proof. As the temperature of the device changes, dew condensation occurs inside the sealed casing, and because of this, it is important to ensure that the adhesive surface of the strain gauge 6 and the adhesive surface of the film sheet maintain their waterproof and moisture-proof functions. The drawback was that it could not be guaranteed.

Therefore, there is a technique of coating and lining the strain gauge 6 and the conductive wire 8 with an adhesive or a lining sheet so as to wrap around the strain body 3 in a manner that covers the strain gauge 6 and the conductive wire 8. It is difficult to maintain a perfect airtight seal, and the connection between the flat part and the corner part is narrow and complicated, so it is difficult to ensure that the lining and coating are perfect. Disadvantages include poor work efficiency and high costs because the work is carried out in a narrow space.

To deal with this, for example,
In the device shown in the publication, a notch 9 for the strain detection section 5 is formed in the upper and lower surfaces 4 of the strain-generating body 3 provided on the mounting support 2', as shown in the load cell 1' shown in FIG. Strain gauge 6,6
and connect them to the compensation resistor block 6' and terminal plate 6'' via lead wires 8, 8, etc., and connect the strain gauges 6, 6 to the notch 9.
A cover 9' is attached after the attachment of the cover 9'.

However, in this type of known technology, the bridge circuit, the compensation resistor, and the lead wires connecting these must be coated separately, which has the disadvantage of increasing the number of work steps and increasing costs. This has the disadvantage that the length of the lead wire becomes long, making it difficult to design the wiring resistance.During the installation work, the lead wire is routed around the strain-generating body, so the work must be done with great care. There was a problem that the workability deteriorated.

In addition, the lead wire is pulled out from between the notch and the cover and connected to the resistance block or terminal board, so when cleaning it or when it is installed in a sealed casing and there is moisture, the lead wire can be pulled out from between the notch and the cover. The disadvantage was that moisture could seep into the interior, causing an unexpected situation.

<Purpose of the invention> The purpose of the invention of this application is to solve the technical problems of waterproofing, moisture-proofing, and workability associated with attaching strain gauges and conductive wires to strain detection parts of load cells based on the above-mentioned prior art. It is possible to easily and accurately attach strain gauges, conductive wires, printed circuit boards, bridge circuits, compensation resistors, and other electrical components to the strain detection part of the flexure element, and it is also useful for moisture-proof coatings, etc. It is an object of the present invention to provide an excellent strain-generating body structure of a load cell that can achieve perfect moisture-proof sealing and is useful in the field of load detection technology in various manufacturing and distribution industries.

<Means/effects for solving the problem> In accordance with the above-mentioned purpose, the structure of the invention of this application, which is summarized in the above-mentioned utility model registration claims, is to solve the above-mentioned problem by using a load cell made of aluminum, etc. When manufacturing the body, strain gauges and conductive wires that are attached to the strain detection part in the later process, and
A predetermined number of notches of a predetermined depth are formed for attaching to electrical equipment such as a Wheatstone bridge circuit or a compensation resistor, and at this time, a strain corresponding to the designed load is formed in the strain detection part, and the After manufacturing the strain body, all the above-mentioned electrical components are attached to the notch at once, and the coating is filled so that it is inside the notch below the level of the side surface of the strain body, and the conductive wire provided inside the strain body is inserted. Insert the conductive wire from the cable through the hole, connect the conductive wire, strain gauge, or connection terminal of the conductive wire through the hole provided at the end of the notch, and then It is possible to apply seal lining or coating to the entire surface of the strain-generating body, and there is no crossing of conductive wires, etc. on the outer surface of the strain-generating body.
Technical measures have been taken to prevent disconnection due to fraying, etc., and to provide complete waterproof and moisture-proof functions to the strain gauge and conductive wire inside the notch.

<Example> Next, one example of the invention of this application will be described as the first and second examples.
The explanation will be as follows based on the figures.

Incidentally, parts having the same features as those in FIGS. 3 and 4 will be described using the same reference numerals.

In the load cell 1'', a strain-generating body 3 made of aluminum or the like having a substantially rectangular side surface is attached in a cantilever manner to a mounting support 2 for a target device, as in the conventional embodiment, and a strain detection section 5, A race track type notch 9 having a flat bottom is formed at a predetermined depth along the longitudinal direction on the upper and lower surfaces 4 of 5.

The wall surface 10 is made deep enough to cover the mounting height of the strain gauge, the Wheatstone bridge, the electrical component conductive wires of the compensation resistor, or a printed circuit board such as an FPC on which these are printed.

These notches 9 also cause the strain-generating body 3 to
The molding process is performed so that linear strain formation with respect to the load in the strain detection parts 5, 5, . . . occurs as designed.

A hole 11 for taking out the lead wire from the cable formed at the end of the notch 9 is bored vertically or at a predetermined angle of inclination, and tunnel-shaped insertion holes 12 and 13 in the strain-generating body 3 are formed. It is designed to be connected to the cable insertion hole 7 of the support body 2 through the cable insertion hole 7 of the support body 2.

After manufacturing the flexure element 3, when integrally fixing it to the support 2, a cable (not shown) is inserted into the cable insertion hole 7 of the support 2, and its lead wire is passed through the insertion holes 12 and 13. Then, in a separate process, strain gauges 6, 6, Wheatstone bridge circuit 61, compensation resistance block 62, and
Further, an electric component made of conductive wires or a printed circuit board printed with these is pasted with a coating agent or the like, and lead wires are connected to fix the strain-generating body 3 in a predetermined position to the support body 2 in a cantilever manner.

In this assembled state, the strain gauge 6 and the Wheatstone bridge circuit 6 in each notch 9
1. An electrical component such as a compensation resistor 62, a conductive wire, or a printed circuit board is fully adhered to the inner bottom surface of the notch 9 within the height of the wall surface 10, and the upper and lower surfaces 4,
It is not made to protrude from 4.

After these electrical components are set in the notch 9, the notch 9 is filled with a sealing adhesive, or the electrical equipment is pasted on the upper and lower surfaces 4 with a coating agent, The notch 9 is completely sealed to complete the waterproof and moisture-proof functions for the electrical equipment, and the load cell 1'' is completed and installed in a load detection unit such as an electronic scale.

Of course, at this time, the load cell 1'' may be further installed in a waterproof watertight casing or the like as appropriate.

In the above configuration, when the load cell 1'' is put into use, the strain detection sections 5, 5... are linearly distorted as designed in response to a load applied to the sensing section, and therefore, the strain detection sections 5, 5... are linearly distorted as designed. Strain gauges 6, 6 attached to the notches 9, 9 on the upper and lower surfaces 4, 4 of ... detect the weight and convert it into an electrical signal,
The function of transmitting data to a computer (not shown) via a cable via a conductive wire to measure gravity, etc. is the same as in the conventional mode.

Of course, as mentioned above, the formation of the notch 9 does not impair the strain detection function of the strain detection sections 5, 5, . . . .

Therefore, as mentioned above, as in the general case, periodic
When cleaning the measuring device on an irregular basis, cleaning water, etc. is poured from above the device, or when the temperature drops from a high temperature state while the device is in use, causing dew condensation inside the casing. Also, there is no water leakage,
In addition, moisture does not enter due to capillary action, and the notch 9
All the electrical equipment is completely coated or lined with a seal film, etc. so that it is buried, so the strain gauge 6 and conductive wires are attached, or the printed circuit board is attached. There is no risk of causing a peeling phenomenon or an electric leakage phenomenon affecting the load cell 1'', and the function of the load cell 1'' is completely guaranteed.

It goes without saying that the embodiment of the invention of this application is not limited to the above-mentioned embodiment. For example, instead of having one notch as in the above-mentioned embodiment, a notch may be formed for each strain gauge or printed circuit board. Various methods can be adopted, such as increasing the rigidity of the strain detecting section and providing holes for the insertion of conductive wires in these notches and the like.

Furthermore, it goes without saying that the present invention is applicable not only to electronic scales and set weighing devices, but also to general load testing devices.

<Effects of the invention> As described above, according to the invention of this application, the strain gauge and conductive wire of the strain body of a load cell installed in an electronic scale, etc., or the strain body of the installed part of a printed circuit board, etc. During manufacturing, by forming a notch that allows electrical components to be attached sufficiently within the level of the upper and lower surfaces, it is possible to fill the mounting surface of the notch with a sealing film or coating agent, ensuring that all electrical components are buried. The excellent effect of completely obtaining waterproof and moisture-proof properties can be achieved by applying this method.

In addition, since strain gauges, conductive wires, and printed circuit boards can be attached to the flat part of the inner bottom of the notch, there is no need to hold the conductive wires against corners, etc., and there is no disconnection or electrical leakage due to fraying, etc., which is an advantage. effect is produced.

Further, the lead wire does not protrude from the notch beyond the ridge, and moisture leakage due to capillary tubes does not occur through the lead wire.

In this respect, the same effect can be obtained because the lead wire insertion hole can be coated.

In addition, electrical components such as strain gauges, Wheatstone bridge circuits, compensation resistors, and printed circuit boards with conductive wires can be attached to the notch as per the settings, making it easier to perform complicated work such as soldering conductive wires. This eliminates the need to perform this process, which not only makes the work easier, but also has the excellent effect of promoting accuracy improvement.

In addition, because electrical components such as strain gauges, Wheatstone bridge circuits, and compensation resistors can be set in the notch all at once, the number of man-hours and processes is reduced and the work is easy to do, and in addition, it is compact and easy to handle. is played.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of one embodiment of the invention of this application, FIG. 1 is a perspective view of the main part, FIG. 2 is a plan sectional view of FIG. 1, and FIGS. 3 and 4 are conventional 1 is a perspective view of a load cell based on the technology; FIG. 5... Strain detection section, 6... Strain gauge, 8
...Conductive wire, 1''...Load cell, 3...Strain element,
9...notch, 61...Wheatstone bridge circuit, 62...compensation resistor.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a strain-generating body structure of a load cell in which a strain gauge attached to a notch formed in a recess in a strain detection part is connected to a conductive wire forming a Wheatstone bridge, A notch in the strain detection section is formed deep enough to attach all the electrical components of the strain gauge, Wheatstone bridge circuit, and compensation resistor to its inner bottom, and a coating agent is applied to the notch to attach all the electrical components to the inner bottom. A strain-generating structure of a load cell characterized by being filled in a buried state. (2) A strain-generating body structure for a load cell according to claim 1, wherein a plurality of the notches are formed and an insertion hole for a conductive wire is formed in the partition wall of the notches. (3) The strain-generating body structure of the load cell according to claim 2, wherein the insertion hole is filled with a coating agent. (4) The strain-generating body structure of a load cell according to claim 1, which is characterized in that a conductive wire insertion hole is formed at the bottom of the notch.