JP2013205133A

JP2013205133A - Load cell

Info

Publication number: JP2013205133A
Application number: JP2012072790A
Authority: JP
Inventors: Masumi Fujimoto; 真澄藤本; Toru Takahashi; 孝橋　　徹
Original assignee: Yamato Scale Co Ltd
Current assignee: Yamato Scale Co Ltd
Priority date: 2012-03-28
Filing date: 2012-03-28
Publication date: 2013-10-07

Abstract

PROBLEM TO BE SOLVED: To provide a highly responsive and low-cost load cell suited to protection of a distortion sensor from an external environment.SOLUTION: A load cell includes a fixed part 2 and a movable part 3, a pair of upper and lower beam parts 4 and 5, and a cylindrical part 6 located between both beam parts 4 and 5 and extended in front and back direction between the fixed part 2 and the movable part 3. The cylindrical part 6 has its outer periphery connected, in a part of the front and back direction, to the fixed part 2 and the movable part 3 via a connection part 18. Pairs of upper through-holes 7 and 8 and lower through-holes 9 and 10 are formed on an upper beam 4 side and a lower beam side. A distance between two distortion parts 4a and 4b and 5a and 5b of each of the beam parts 4 and 5, and a distance between two distortion parts 18a and 18b, and 18c and 18d of the outer peripheries of the cylindrical part 6, are shortened to increase a unique vibration frequency, thereby enabling fast response. Further, formation of connection grooves for respectively connecting the pairs of upper through-holes 7 and 8 and lower through-holes 9 and 10 is made unnecessary.

Description

本発明は、台秤、計量タンク、計量ホッパ等の各種計量装置に用いられるロードセルに関する。 The present invention relates to a load cell used in various weighing devices such as a platform scale, a weighing tank, and a weighing hopper.

歪量を検出する歪センサの一種である歪ゲージを、起歪体に貼着して、負荷荷重による起歪部の伸縮量を歪ゲージの抵抗値変化による電気信号に変換して負荷荷重の大きさに比例する荷重信号を発生するロードセルにおいて、前記歪ゲージ部分等を密封して外部環境から保護するものとして、例えば、特許文献１に示す防水仕様のロードセルがある。 A strain gauge, which is a type of strain sensor that detects the amount of strain, is attached to the strain generating body, and the amount of expansion / contraction of the strained portion due to the load is converted into an electrical signal due to a change in the resistance value of the strain gauge. In a load cell that generates a load signal proportional to the size, a waterproof load cell disclosed in Patent Document 1 is known as an example of sealing the strain gauge portion and the like to protect it from the external environment.

図１２は、この特許文献１のロードセルの正面図であり、図１３は、その断面図である。 FIG. 12 is a front view of the load cell of Patent Document 1, and FIG. 13 is a cross-sectional view thereof.

このロードセル５０は、荷重を受ける受台が取付けられる可動部５１、計量装置の基台等のベースに取付けられる固定部５２、および、それらを連結する上下のビーム部５３，５４を備えている。 The load cell 50 includes a movable portion 51 to which a receiving base for receiving a load is attached, a fixed portion 52 to be attached to a base such as a base of a weighing device, and upper and lower beam portions 53 and 54 that connect them.

左右方向の両側の前記可動部５１と前記固定部５２との間には、前後方向（図１２の紙面に垂直方向、図１３の上下方向）に延びる薄肉の円筒部５５が形成されており、該円筒部５５の前後方向の中央部分において、その外周の一部が、連結部５６を介して可動部５１及び固定部５２とそれぞれ連結されている。 Between the movable portion 51 and the fixed portion 52 on both sides in the left-right direction, a thin cylindrical portion 55 extending in the front-rear direction (a direction perpendicular to the paper surface of FIG. 12 and a vertical direction of FIG. 13) is formed. In the central portion of the cylindrical portion 55 in the front-rear direction, a part of the outer periphery thereof is connected to the movable portion 51 and the fixed portion 52 via the connecting portion 56, respectively.

円筒部５５の周囲の上ビーム部５３側には、一対の貫通円孔６６，６７が形成されると共に、それらを繋ぐ連結溝６８が形成され、また、円筒部５５の周囲の下ビーム部５４側には、一対の貫通円孔６９，７０が形成されると共に、それらを繋ぐ連結溝７１が形成される。 A pair of through-holes 66 and 67 are formed on the upper beam portion 53 side around the cylindrical portion 55, and a connecting groove 68 is formed to connect them, and the lower beam portion 54 around the cylindrical portion 55 is formed. A pair of through-holes 69 and 70 are formed on the side, and a connecting groove 71 that connects them is formed.

上ビーム部５３側の一対の貫通円孔６６，６７によって、上ビーム部５３には、薄肉の起歪部５３ａ，５３ｂが形成される一方、円筒部５５の外周の連結部５６には、薄肉の起歪部５６ａ，５６ｂが形成される。また、下ビーム部５４側の一対の貫通円孔６９，７０によって、下ビーム部５４には、薄肉の起歪部５４ａ，５４ｂが形成される一方、円筒部５５の外周の連結部５６には、薄肉の起歪部５６ｃ，５６ｄが形成される。 The pair of through-holes 66 and 67 on the upper beam portion 53 side form thin strain-generating portions 53 a and 53 b in the upper beam portion 53, while the connection portion 56 on the outer periphery of the cylindrical portion 55 has a thin wall. The strain generating portions 56a and 56b are formed. The pair of through-holes 69 and 70 on the lower beam portion 54 side form thin strain-generating portions 54 a and 54 b in the lower beam portion 54, while the connection portion 56 on the outer periphery of the cylindrical portion 55 Thus, thin strain generating portions 56c and 56d are formed.

前記円筒部５５の外周の各起歪部５６ａ〜５６ｄに対応して円筒部５５の内周面には、４つの歪ゲージ５７〜６０が貼着されており、これら歪ゲージ５７〜６０部分の防水を図るために、円筒形の金属製の密閉カバー６１を嵌め込み、この密閉カバー６１の両端部と円筒部５５とを溶接し、歪ゲージ５７〜６０部分を密封している。 Four strain gauges 57 to 60 are attached to the inner peripheral surface of the cylindrical portion 55 corresponding to the respective strain generating portions 56a to 56d on the outer periphery of the cylindrical portion 55. For waterproofing, a cylindrical metal sealing cover 61 is fitted, both ends of the sealing cover 61 and the cylindrical portion 55 are welded, and the strain gauges 57 to 60 are sealed.

また、固定部５２には、歪ゲージ５７〜６０と外部とを配線接続するための配線や回路基板等が収納された収納室６２が形成されており、この収納室６２は、連通孔６３を介して外部に連通する一方、上述の連結部５６に形成された接続孔６４を介して円筒部５５の内周面に接続されている。歪ゲージ５７〜６０は、接続孔６４、収納室６２及び連通孔６３を介して外部と配線接続される。この収納室６２は、開口部に金属製の蓋体６５が溶接されて、防水が図られている。 In addition, the fixing portion 52 is formed with a storage chamber 62 in which wiring for connecting the strain gauges 57 to 60 to the outside, a circuit board, and the like are stored. While communicating with the outside via the connection portion 64, the connection portion 64 is connected to the inner peripheral surface of the cylindrical portion 55 via the connection hole 64. The strain gauges 57 to 60 are connected to the outside via the connection hole 64, the storage chamber 62, and the communication hole 63. The storage chamber 62 is waterproofed by welding a metal lid 65 to the opening.

このロードセル５０では、負荷荷重が可動部５１に加えられると、上下のビーム部５３，５４の起歪部５３ａ，５３ｂ；５４ａ，５４ｂが撓むと共に、円筒部５５の外周の連結部５６の起歪部５６ａ〜５６ｄが撓み、歪応力が集中する円筒部５５の内周面に貼着された歪ゲージ５７〜６０によって伸縮歪応力を検出し、負荷荷重が荷重信号に変換される。 In the load cell 50, when a load is applied to the movable portion 51, the strain-generating portions 53 a and 53 b and 54 a and 54 b of the upper and lower beam portions 53 and 54 are bent and the connection portion 56 on the outer periphery of the cylindrical portion 55 is raised. The strain portions 56a to 56d are deflected, and the strain gauges 57 to 60 attached to the inner peripheral surface of the cylindrical portion 55 where the strain stress is concentrated are detected, and the load load is converted into a load signal.

米国特許第４，４８８，６１１号U.S. Pat. No. 4,488,611

ロードセルを用いた計量装置では、高速計量を行うために、計量時間の短縮の要請が高まっており、応答性の高いロードセルが求められている。ロードセルの応答性を高くするためには、ロードセルの固有振動周期を短くする必要があり、したがって、ロードセルの固有振動数ｆを高める必要がある。 In a weighing device using a load cell, in order to perform high-speed weighing, there is an increasing demand for shortening the weighing time, and a load cell with high responsiveness is required. In order to increase the responsiveness of the load cell, it is necessary to shorten the natural vibration period of the load cell, and therefore it is necessary to increase the natural frequency f of the load cell.

ここで、ロードセルに負荷される荷重をＦ、荷重Ｆが負荷された可動部の変位量をδ、ロードセルの質量をＭ、ロードセルのバネ定数をｋとすると、次の関係式で表される。 Here, when the load applied to the load cell is F, the displacement amount of the movable part loaded with the load F is δ, the mass of the load cell is M, and the spring constant of the load cell is k, the following relational expression is expressed.

ｋ＝Ｆ／δ …（１）
ｆ＝（１／２π）√（ｋ／Ｍ） …（２）
（２）式に（１）式を代入すると、
ｆ＝（１／２π）√[Ｆ／（δ・Ｍ）]となる。 k = F / δ (1)
f = (1 / 2π) √ (k / M) (2)
Substituting equation (1) into equation (2),
f = (1 / 2π) √ [F / (δ · M)].

ロードセルの質量Ｍは一定であり、荷重Ｆに対して、固有振動数ｆを高めるには、変位量δ（撓み量）を小さくすればよい。 The mass M of the load cell is constant, and in order to increase the natural frequency f with respect to the load F, the displacement amount δ (deflection amount) may be reduced.

上記特許文献１のロードセル５０では、モーメントアームと呼ばれる平行リンクを構成する上下のビーム部５３，５４の２箇所の起歪部５３ａ，５３ｂ；５４ａ，５４ｂ間の距離Ｌ´が長いために負荷荷重に対して大きなモーメント力が作用し、撓み量が大きくなる。つまり、前記距離Ｌ´が長いために、バネ定数が小さくなるので、固有振動数を高く設定することができず、高い応答性が求められる高速計量には十分に対応できない。 In the load cell 50 of the above-mentioned patent document 1, since the distance L ′ between the two strain generating portions 53a, 53b; 54a, 54b of the upper and lower beam portions 53, 54 constituting a parallel link called a moment arm is long, For this, a large moment force acts and the amount of bending increases. That is, since the distance L ′ is long, the spring constant becomes small, so that the natural frequency cannot be set high, and it cannot sufficiently cope with high-speed weighing that requires high responsiveness.

また、上記ロードセル５０の加工では、上下のビーム部５３，５４及びこれらに起歪部５３ａ，５３ｂ；５４ａ，５４ｂを形成するために、各一対の貫通円孔６６，６７；６９，７０をそれぞれ形成した上に、上記距離Ｌ´を隔てた各一対の貫通円孔６６，６７；６９，７０同士を連結する連結溝６８，７１を切削加工しなければならず、加工コストが高くつくという課題がある。 Further, in the processing of the load cell 50, in order to form the upper and lower beam portions 53, 54 and the strain generating portions 53a, 53b; 54a, 54b, the pair of through-holes 66, 67; In addition, the connection grooves 68 and 71 that connect the pair of through-holes 66 and 67; 69 and 70 separated by the distance L ′ must be cut and the processing cost is high. There is.

本発明は、上述のような実情に着目してなされたものであって、応答性に優れると共に、コストが低く、しかも、歪センサ部分を外部環境から保護するのに好適なロードセルを提供することを目的とする。 The present invention has been made paying attention to the above situation, and provides a load cell that is excellent in responsiveness, low in cost, and suitable for protecting the strain sensor portion from the external environment. With the goal.

上記目的を達成するために、本発明では次のように構成している。 In order to achieve the above object, the present invention is configured as follows.

（１）本発明のロードセルは、左右方向の一端側の固定部及び他端側の可動部と、前記固定部及び前記可動部の上部同士及び下部同士をそれぞれ連結する上下一対のビーム部とを備え、前記両ビーム部の間であって、かつ前記固定部と前記可動部との間に、前後方向に延びる円筒部を有し、該円筒部は、前後方向の一部において、その外周が、連結部を介して前記固定部及び前記可動部に連結され、前記上ビーム部側には、前後方向に貫通する一対の上部貫通孔が、近接または一部が重なり合うように形成される一方、前記下ビーム部側には、前後方向に貫通する一対の下部貫通孔が、近接または一部が重なり合うように形成され、前記一対の上部貫通孔によって、前記上ビーム部には、起歪部が２箇所に形成される一方、前記円筒部の外周の前記連結部には、起歪部が２箇所に形成され、前記一対の下部貫通孔によって、前記下ビーム部には、起歪部が２箇所に形成される一方、前記円筒部の外周の前記連結部には、起歪部が２箇所に形成される。 (1) The load cell of the present invention includes a fixed portion on one end side in the left-right direction and a movable portion on the other end side, and a pair of upper and lower beam portions that connect the upper portion and the lower portion of the fixed portion and the movable portion, respectively. A cylindrical portion extending in the front-rear direction between the beam portions and between the fixed portion and the movable portion, and the outer periphery of the cylindrical portion is partially in the front-rear direction. A pair of upper through holes penetrating in the front-rear direction are formed on the upper beam portion side so as to be close or partially overlapped with each other, connected to the fixed portion and the movable portion via a connecting portion, A pair of lower through-holes penetrating in the front-rear direction is formed on the lower beam portion side so as to be close to each other or partially overlapped, and the upper beam portion has a strain-generating portion by the pair of upper through-holes. On the other hand, the outer periphery of the cylindrical part is formed in two places The connecting portion is formed with two strain-generating portions, and the pair of lower through-holes is formed with two strain-generating portions in the lower beam portion, while the outer periphery of the cylindrical portion is The connecting portion is formed with two strain generating portions.

一対の上部貫通孔、及び、一対の下部貫通孔をそれぞれ近接して形成する場合には、上部貫通孔間の距離、及び、下部貫通孔間の距離は、起歪部に発生する応力に影響を与えない距離以内とされ、隣合う上部貫通孔、及び、隣合う下部貫通孔は、可及的に近接するのが好ましい。 When a pair of upper through-holes and a pair of lower through-holes are formed close to each other, the distance between the upper through-holes and the distance between the lower through-holes affect the stress generated in the strain generating portion. It is preferable that the adjacent upper through hole and the adjacent lower through hole be as close as possible to each other.

本発明のロードセルによると、上ビーム部側及び下ビーム部側には、各一対の上部貫通孔及び下部貫通孔を、近接または一部が重なり合うようにそれぞれ形成したので、上ビーム部の２箇所の起歪部間の距離及び円筒部の外周の上ビーム部寄りの２箇所の起歪部間の距離を短くできると共に、下ビーム部の２箇所の起歪部間の距離及び円筒部の外周の下ビーム部寄りの２箇所の起歪部間の距離を短くできる、すなわち、モーメントアームを短くできるので、撓み量が小さくなり、固有振動数を高くして高速応答が可能となる。 According to the load cell of the present invention, a pair of upper and lower through holes are formed on the upper beam portion side and the lower beam portion side so as to be close to each other or partially overlap each other. The distance between the two strain generating portions and the distance between the two strain generating portions near the upper beam portion of the outer periphery of the cylindrical portion can be shortened, and the distance between the two strain generating portions of the lower beam portion and the outer periphery of the cylindrical portion can be reduced. Since the distance between the two strain-generating portions near the lower beam portion can be shortened, that is, the moment arm can be shortened, the amount of bending is reduced, and the natural frequency is increased to enable high-speed response.

しかも、各一対の上部貫通孔及び下部貫通孔は、近接または一部が重なり合うように形成されるので、従来例のように間隔のあいた一対の貫通孔間を繋ぐ連結溝を切削加工して形成する必要がなく、加工コストを低減することができる。 Moreover, each pair of upper and lower through-holes is formed so as to be close to each other or partially overlapped with each other, so that a connecting groove connecting between a pair of spaced-apart through-holes is formed by cutting as in the conventional example. There is no need to do so, and the processing cost can be reduced.

更に、円筒部の外周の起歪部に対応させて円筒部の内周面に歪センサを装着し、円筒部に保護カバーを嵌め込んで、歪センサ部分を外部環境から保護するといったことが可能となる。 Furthermore, it is possible to attach a strain sensor to the inner peripheral surface of the cylindrical portion corresponding to the strain generating portion on the outer periphery of the cylindrical portion, and to protect the strain sensor portion from the external environment by fitting a protective cover on the cylindrical portion. It becomes.

（２）本発明のロードセルの好ましい実施態様では、前記円筒部は、前後方向の中央部分において、その外周が前記連結部を介して前記固定部及び前記可動部に連結され、前記一対の上部貫通孔及び前記一対の下部貫通孔は、前記円筒部の内径よりも小さな直径の貫通円孔であって、各一対の前記貫通円孔の一部がそれぞれ重なり合うように前記左右方向に沿って形成される。 (2) In a preferred embodiment of the load cell of the present invention, the cylindrical portion has an outer periphery connected to the fixed portion and the movable portion via the connecting portion at a center portion in the front-rear direction, and the pair of upper through holes The hole and the pair of lower through-holes are through-holes having a diameter smaller than the inner diameter of the cylindrical portion, and are formed along the left-right direction so that a part of each of the pair of through-holes overlap each other. The

この実施態様によると、各一対の上部貫通孔及び下部貫通孔は、円筒部の内径よりも小さな直径の貫通円孔であって、各一対の貫通円孔が、その一部が重なり合うように左右方向に沿って形成されるので、当該ロードセルを左右方向及び上下方向に小さくして小型化することができる。 According to this embodiment, each pair of upper and lower through-holes is a through-hole having a diameter smaller than the inner diameter of the cylindrical portion, and each pair of through-holes is left and right so that a part thereof overlaps. Since it is formed along the direction, the load cell can be reduced in size in the left-right direction and the up-down direction.

（３）本発明のロードセルの別の実施態様では、荷重によって変位する前記可動部に当接して該可動部の変位を規制するストッパが、前記固定部側から可動部側へ延出形成され、前記可動部及び前記ストッパは、互い対向する対向面をそれぞれ有し、両対向面間に、ストッパ用隙間が形成される。 (3) In another embodiment of the load cell of the present invention, a stopper that contacts the movable portion that is displaced by a load and regulates the displacement of the movable portion is formed to extend from the fixed portion side to the movable portion side, The movable portion and the stopper have opposing surfaces that face each other, and a stopper gap is formed between the opposing surfaces.

この実施態様によると、当該ロードセルの可動部に過大な荷重が作用すると、可動部が変位して、ストッパ用隙間を構成するストッパの対向面に当接して、その変位が規制されるので、過負荷によるロードセルの破損を防止することができる。 According to this embodiment, when an excessive load is applied to the movable part of the load cell, the movable part is displaced and abuts against the opposing surface of the stopper that forms the stopper gap, so that the displacement is regulated. It is possible to prevent the load cell from being damaged by the load.

なお、前記ストッパは、可動部の前記変位方向とは、逆方向にも形成し、逆方向の変位も規制できるようにするのが好ましい。 The stopper is preferably formed in a direction opposite to the displacement direction of the movable portion so that the displacement in the reverse direction can be restricted.

（４）本発明のロードセルの他の実施態様では、前記可動部には、当該可動部に受け台を取付けるための取付け孔が形成され、前記取付け孔と前記円筒部の外周との間に、前後方向に貫通する貫通孔が形成される。 (4) In another embodiment of the load cell of the present invention, the movable part is formed with an attachment hole for attaching a cradle to the movable part, and between the attachment hole and the outer periphery of the cylindrical part, A through hole penetrating in the front-rear direction is formed.

この実施態様によると、可動部の取付孔と円筒部の外周との間には、貫通孔が形成されるので、可動部に荷重を受ける受け台を取付けるための応力が、円筒部の外周の起歪部に与える影響を阻止することができ、これによって、可動部の取付面と円筒部との距離を短くすることができ、当該ロードセルの左右方向の長さを短くして小型化を図ることができる。 According to this embodiment, since the through hole is formed between the mounting hole of the movable portion and the outer periphery of the cylindrical portion, the stress for mounting the cradle receiving the load on the movable portion is The influence on the strain generating portion can be prevented, and thereby the distance between the mounting surface of the movable portion and the cylindrical portion can be shortened, and the length of the load cell in the left-right direction can be shortened to reduce the size. be able to.

このように本発明のロードセルによれば、上ビーム部側及び下ビーム部側には、各一対の上部貫通孔及び下部貫通孔を、近接または一部が重なり合うように形成したので、上ビーム部の２箇所の起歪部間の距離及び円筒部の外周の上ビーム部寄りの２箇所の起歪部間の距離を短くできると共に、下ビーム部の２箇所の起歪部間の距離及び円筒部の外周の下ビーム部寄りの２箇所の起歪部間の距離を短くできるので、ロードセルの固有振動数を高くして応答を速くすることができ、高速計量が可能となる。 As described above, according to the load cell of the present invention, the upper beam portion side and the lower beam portion side are formed so that each pair of upper through hole and lower through hole is close to each other or partially overlapped. The distance between the two strain generating portions and the distance between the two strain generating portions near the upper beam portion on the outer periphery of the cylindrical portion can be shortened, and the distance between the two strain generating portions of the lower beam portion and the cylinder Since the distance between the two strain generating parts near the lower beam part on the outer periphery of the part can be shortened, the response frequency can be increased by increasing the natural frequency of the load cell, and high-speed weighing is possible.

しかも、各一対の上部貫通孔及び下部貫通孔は、近接または一部が重なり合うに形成されるので、従来例のように、間隔があいた一対の貫通孔間を繋ぐ連結溝を切削加工する必要がなく、加工コストを低減することができる。 Moreover, each pair of upper and lower through-holes is formed close to or partially overlapping, so that it is necessary to cut a connecting groove connecting a pair of spaced-apart through-holes as in the conventional example. In addition, the processing cost can be reduced.

更に、円筒部の内周面に、歪センサを装着し、その内周面を覆うように、金属製のカバー等を溶接して歪センサを密封して外部環境から容易に保護するといったことが可能となる。 Furthermore, a strain sensor is attached to the inner peripheral surface of the cylindrical portion, and a metal cover or the like is welded so as to cover the inner peripheral surface, thereby sealing the strain sensor and easily protecting it from the external environment. It becomes possible.

図１は本発明の一実施形態に係るロードセルの取付け状態を示す図である。FIG. 1 is a view showing an attached state of a load cell according to an embodiment of the present invention. 図２は図１のロードセルの正面図である。FIG. 2 is a front view of the load cell of FIG. 図３は図１のロードセルの平面図である。FIG. 3 is a plan view of the load cell of FIG. 図４は本発明の他の実施形態のロードセルの正面図である。FIG. 4 is a front view of a load cell according to another embodiment of the present invention. 図５は図４のロードセルの平面図である。FIG. 5 is a plan view of the load cell of FIG. 図６は本発明の更に他の実施形態のロードセルの正面図である。FIG. 6 is a front view of a load cell according to still another embodiment of the present invention. 図７は図６のロードセルの平面図である。FIG. 7 is a plan view of the load cell of FIG. 図８は本発明の他の実施形態のロードセルの正面図である。FIG. 8 is a front view of a load cell according to another embodiment of the present invention. 図９は図８の切断面線Ａ−Ａから見た断面図である。FIG. 9 is a cross-sectional view taken along the section line AA of FIG. 図１０は本発明の更に他の実施形態のロードセルの正面図である。FIG. 10 is a front view of a load cell according to still another embodiment of the present invention. 図１１は本発明の他の実施形態のロードセルの正面図である。FIG. 11 is a front view of a load cell according to another embodiment of the present invention. 図１２は従来例の正面図である。FIG. 12 is a front view of a conventional example. 図１３の図１２の断面図である。It is sectional drawing of FIG. 12 of FIG.

以下、図面によって本発明の実施形態について詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(実施形態１)
図１は、本発明の一実施形態のロードセルの取付け状態を示す図であり、図２は、図１のロードセルの正面図であり、図３は、その平面図である。 (Embodiment 1)
FIG. 1 is a view showing an attachment state of a load cell according to an embodiment of the present invention, FIG. 2 is a front view of the load cell of FIG. 1, and FIG. 3 is a plan view thereof.

この実施形態のロードセル１は、アルミニウムや鉄、ステンレス合金などの直方体状の金属弾性体から成り、左右方向の一端側の固定部２と、他端側の可動部３と、前記両部２，３の上下部分をそれぞれ連結する２本の平行リンクを構成する上下の各ビーム部４，５と、左右方向の中央部付近に前後方向（図１，図２の紙面に垂直方向、図３の上下方向）に延びる薄肉の円筒部６と、該円筒部６と固定部３及び可動部２とをそれぞれ連結する連結部１８と、円筒部６の上下に近接してそれぞれ交差するように貫通形成された各一対の上部貫通円孔７，８、下部貫通円孔９，１０と、固定部２側に形成されて、配線を処理して収納する収納室１１を備えている。 The load cell 1 of this embodiment is composed of a rectangular parallelepiped metal elastic body such as aluminum, iron, and stainless alloy, and includes a fixed portion 2 on one end side in the left-right direction, a movable portion 3 on the other end side, The upper and lower beam portions 4 and 5 constituting two parallel links respectively connecting the upper and lower portions of 3 and the front-rear direction near the central portion in the left-right direction (perpendicular to the plane of FIG. 1 and FIG. A thin cylindrical portion 6 that extends in the vertical direction), a connecting portion 18 that connects the cylindrical portion 6 to the fixed portion 3 and the movable portion 2 respectively, and a penetrating formation so as to cross each other close to the top and bottom of the cylindrical portion 6. Each pair of upper through-holes 7 and 8 and lower through-holes 9 and 10 is provided on the fixed portion 2 side, and a storage chamber 11 for processing and storing the wiring is provided.

固定部２の下面側には、当該ロードセル１を、計量装置の基台１２等のベースに固定するためのねじ孔１３ａ，１３ｂが形成されており、可動部３には、被計量物の荷重を受ける荷重受け台１４を取付けるためのねじ孔１５ａ，１５ｂが形成されている。 Screw holes 13a and 13b for fixing the load cell 1 to a base such as the base 12 of the weighing device are formed on the lower surface side of the fixed portion 2, and the load of the object to be weighed is formed in the movable portion 3. Screw holes 15a and 15b are formed for mounting the load receiving base 14 for receiving the load.

円筒部６は、前後方向に貫通しており、この円筒部６は、前後方向の中央部分において、該円筒部６の外周と可動部３及び固定部２とが連結部１８を介して連結されている。この連結部１８は、上記貫通円孔７，８；９，１０の部分を除いて円筒部６と同心に径方向の外方へ円形に延びて、可動部３及び固定部２に連なっている。 The cylindrical portion 6 penetrates in the front-rear direction. In the central portion of the front-rear direction, the outer periphery of the cylindrical portion 6 is connected to the movable portion 3 and the fixed portion 2 via a connecting portion 18. ing. The connecting portion 18 extends in a circular shape outward in the radial direction concentrically with the cylindrical portion 6 except for the portions of the through-holes 7, 8; 9, 10, and continues to the movable portion 3 and the fixed portion 2. .

円筒部６の上下、すなわち、円筒部６と上ビーム部４との間、及び、円筒部６と下ビーム部５との間には、上述のように、円筒部６の外周にそれぞれ隣接して各一対の上部貫通円孔７，８、下部貫通円孔９，１０が、円筒部６に平行にそれぞれ形成されている。各一対の上部貫通円孔７，８及び下部貫通円孔９，１０は、その一部が重なり合う、すなわち、互いに外周部が交差するように形成されている。この実施形態では、上部貫通円孔７，８及び下部貫通円孔９，１０の直径は等しく、円筒部６内径よりも小さくなっている。 As described above, the upper and lower sides of the cylindrical portion 6, that is, between the cylindrical portion 6 and the upper beam portion 4 and between the cylindrical portion 6 and the lower beam portion 5 are adjacent to the outer periphery of the cylindrical portion 6, respectively. Each pair of upper through-holes 7 and 8 and lower through-holes 9 and 10 are formed in parallel to the cylindrical portion 6. Each pair of the upper through-holes 7 and 8 and the lower through-holes 9 and 10 are formed so that a part thereof overlaps, that is, the outer peripheral parts intersect each other. In this embodiment, the diameters of the upper through holes 7 and 8 and the lower through holes 9 and 10 are equal and smaller than the inner diameter of the cylindrical portion 6.

一対の上部貫通円孔７，８によって、上ビーム部４には、薄肉の可撓部である起歪部（歪発生部）４ａ，４ｂが形成される一方、一対の下部貫通円孔９，１０によって、下ビーム部５には、薄肉の可撓部である起歪部５ａ，５ｂが形成される。ロードセル１の上面から上部貫通円孔７，８までの距離ｄ２、及び、ロードセル１の下面から下部貫通円孔９，１０までの距離ｄ２は、等しく、各起歪部４ａ，４ｂ；５ａ，５ｂの肉厚となる。 By the pair of upper through-holes 7 and 8, the upper beam portion 4 is formed with strain-generating portions (strain generating portions) 4a and 4b which are thin flexible portions, while the pair of lower through-holes 9 and 8 10, strain generating portions 5 a and 5 b which are thin flexible portions are formed in the lower beam portion 5. The distance d2 from the upper surface of the load cell 1 to the upper through-holes 7 and 8 and the distance d2 from the lower surface of the load cell 1 to the lower through-holes 9 and 10 are equal, and the strain generating portions 4a, 4b; 5a, 5b It becomes the wall thickness.

また、一対の上部貫通円孔７，８によって、円筒部６の外周の連結部１８には、薄肉の起歪部１８ａ，１８ｂが形成される一方、一対の下部貫通円孔９，１０によって、円筒部６の外周の連結部１８には、薄肉の起歪部１８ｃ，１８ｄが形成される。円筒部６の外周から上部及び下部の各貫通円孔７，８；９，１０までの距離ｄ１は、いずれも等しく、各起歪部１８ａ〜１８ｄの肉厚となる。荷重に応じた歪を発生させる起歪部１８ａ〜１８ｄに対応して円筒部６の内周面には、４つの歪ゲージ１９ａ〜１９ｄが貼着されている。 The pair of upper through-holes 7 and 8 are formed with thin strain-generating portions 18a and 18b in the connecting portion 18 on the outer periphery of the cylindrical portion 6, while the pair of lower through-holes 9 and 10 Thin connecting portions 18 c and 18 d are formed on the connecting portion 18 on the outer periphery of the cylindrical portion 6. The distances d1 from the outer circumference of the cylindrical portion 6 to the upper and lower through-holes 7, 8; 9, 10 are all equal, and the thickness of each strain-generating portion 18a to 18d is the same. Four strain gauges 19a to 19d are attached to the inner peripheral surface of the cylindrical portion 6 corresponding to the strain generating portions 18a to 18d that generate strain according to the load.

このロードセル１に、図１に示す荷重受け台１４を介して負荷荷重が可動部３に加えられると、２本の平行リンクである上下のビーム部４，５の起歪部４ａ，４ｂ；５ａ，５ｂと共に、円筒部６の外周の連結部１８の起歪部１８ａ，１８ｂ，１８ｃ，１８ｄが撓むことによって、円筒部６の内周面の歪ゲージ１９ａ，１９ｂ，１９ｃ，１９ｄによって伸縮歪応力を検出し、負荷荷重が荷重信号に変換される。 When a load is applied to the load cell 1 via the load cradle 14 shown in FIG. 1, the strain generating portions 4a, 4b; 5a of the upper and lower beam portions 4, 5 which are two parallel links. , 5b and the strain generating portions 18a, 18b, 18c, 18d of the connecting portion 18 on the outer periphery of the cylindrical portion 6 are bent, so that the strain gauges 19a, 19b, 19c, 19d on the inner peripheral surface of the cylindrical portion 6 are stretched. Stress is detected and the applied load is converted into a load signal.

円筒部６の内径は、歪ゲージ１９ａ〜１９ｄを貼付し、配線作業をするのに必要な大きさとなっている。 The inner diameter of the cylindrical portion 6 is a size necessary for attaching the strain gauges 19a to 19d and performing wiring work.

固定部２には、円筒部６の内周面に貼着された歪ゲージ１９ａ〜１９ｄと外部とを配線接続すると共に、歪ゲージ１９ａ〜１９ｄからのアナログ荷重信号の増幅及びＡ／Ｄ変換等を行うための回路基板または外部からの配線と、歪ゲージ１９ａ〜１９ｄからの配線とを中継接続する中継基板等を収納する収納室１１が形成されており、この収納室１１の開口部は、蓋体２０によって密閉されている。 The fixed portion 2 is connected to the outside with strain gauges 19a to 19d attached to the inner peripheral surface of the cylindrical portion 6, and also amplifies analog load signals from the strain gauges 19a to 19d, performs A / D conversion, and the like. A storage chamber 11 is formed for storing a circuit board or a wiring from the outside and a wiring board for relaying and connecting the wiring from the strain gauges 19a to 19d. An opening of the storage chamber 11 is formed as follows. The lid 20 is sealed.

円筒部６の外周の連結部１８及び固定部２には、円筒部６の内周面と前記収納室１１とを繋ぐ連通孔２１が形成される一方、固定部２の端部には、収納室１１と外部とを配線接続するための接続孔２２が形成されている。円筒部６の内周面の歪ゲージ１９ａ〜１９ｄと外部とは、連通孔２１、収納室１１及び接続孔２２を介して配線接続される。 The connecting portion 18 and the fixed portion 2 on the outer periphery of the cylindrical portion 6 are formed with a communication hole 21 that connects the inner peripheral surface of the cylindrical portion 6 and the storage chamber 11, while the end portion of the fixed portion 2 is stored at the end. A connection hole 22 for wiring connection between the chamber 11 and the outside is formed. The strain gauges 19 a to 19 d on the inner peripheral surface of the cylindrical portion 6 and the outside are connected to each other via the communication hole 21, the storage chamber 11, and the connection hole 22.

この実施形態のロードセル１では、円筒部６の上下の各一対の上部貫通円孔７，８及び下部貫通円孔９，１０を、その外周部を交差させるように形成したので、上下のビーム部４，５の起歪部４ａ，４ｂ；５ａ，５ｂ間の距離Ｌ及び円筒部６の外周の連結部１８の起歪部１８ａ，１８ｂ；１８ｃ，１８ｄ間の距離が短くなる、すなわち、モーメントアームが短くなるので、撓み量が小さくなり、固有振動数を高くして応答を速くすることができ、これによって高速計量が可能となる。 In the load cell 1 of this embodiment, the pair of upper and lower upper through holes 7 and 8 and the lower through holes 9 and 10 of the upper and lower portions of the cylindrical portion 6 are formed so as to intersect the outer peripheral portions thereof. 4 and 5, the distance L between 5a and 5b and the distance between the strain portions 18a and 18b and 18c and 18d of the connecting portion 18 on the outer periphery of the cylindrical portion 6 are reduced, that is, a moment arm. Therefore, the amount of flexure is reduced, the natural frequency can be increased, and the response can be made faster, thereby enabling high-speed weighing.

しかも、図１２，１３の従来例のように、円筒部６の上下の各一対の貫通孔６６，６７；６９，７０をそれぞれ連結するための連結溝６８，７１を切削加工で形成する必要がなく、その分、加工コストを低減することができる。 Moreover, as in the conventional example of FIGS. 12 and 13, it is necessary to form the connecting grooves 68 and 71 for connecting the pair of upper and lower through holes 66, 67; Therefore, the processing cost can be reduced accordingly.

(実施形態２)
図４は、本発明の他の実施形態のロードセル１ａの正面図であり、図５は、その平面図であり、上述の実施形態に対応する部分には、同一の参照符号を付す。 (Embodiment 2)
FIG. 4 is a front view of a load cell 1a according to another embodiment of the present invention. FIG. 5 is a plan view of the load cell 1a. Parts corresponding to those of the above-described embodiment are denoted by the same reference numerals.

ロードセルでは、過負荷（定格荷重を超える荷重）によるロードセルの破損を防ぐために、過負荷防止機構を備えたものがあり、この過負荷防止機構としては、例えば、固定位置のストッパに対して、可動部に形成したねじ孔にボルトをねじ込み、ボルトの先端と前記ストッパとの当接によって可動部の変位を規制して過剰な負荷がかからないようにしたものがある。 Some load cells are equipped with an overload prevention mechanism to prevent damage to the load cell due to overload (load exceeding the rated load). For example, this overload prevention mechanism is movable against a stopper at a fixed position. There is a type in which a bolt is screwed into a screw hole formed in the portion, and the displacement of the movable portion is restricted by contact between the tip of the bolt and the stopper so that an excessive load is not applied.

高速応答が可能なロードセルでは、上述のように撓み量が小さくなるが、撓み量が小さくなると、それを規制する上記のような過負荷防止機構においては、ボルトの先端とストッパとの隙間をロードセルに対して規定する許容最大負荷荷重に対応する撓み量に基づいて極めて小さく設定する必要があり、その隙間の設定作業が容易でない。 In a load cell capable of high-speed response, the amount of bending is reduced as described above. However, when the amount of bending is reduced, the overload prevention mechanism as described above restricts the gap between the tip of the bolt and the stopper. Therefore, it is necessary to set a very small amount based on the amount of deflection corresponding to the allowable maximum load load defined by the above, and it is not easy to set the clearance.

そこで、この実施形態では、過負荷によるロードセル１ａの破損を防ぐために、ロードセル１ａを構成する起歪体に、可動部３の上下の変位を規制する上下のストッパ２３，２４を一体に形成している。 Therefore, in this embodiment, in order to prevent damage to the load cell 1a due to overload, the upper and lower stoppers 23 and 24 for restricting the vertical displacement of the movable portion 3 are integrally formed on the strain body constituting the load cell 1a. Yes.

各ストッパ２３，２４は、直方体状の金属弾性体からなる起歪体に、ストッパ用隙間ｇとなる溝加工を施すことによって形成することができる。この溝加工としては、例えば、ワイヤーカット放電加工またはレーザ加工などの精密機械加工を用いることができる。間隙は、ワイヤ−の太さや、レーザーの光軸の太さ、照射時間を選択することで容易に設定できる。 Each of the stoppers 23 and 24 can be formed by subjecting a strained body made of a rectangular parallelepiped metal elastic body to a groove process to be a stopper gap g. As this grooving, for example, precision machining such as wire cut electric discharge machining or laser machining can be used. The gap can be easily set by selecting the thickness of the wire, the thickness of the optical axis of the laser, and the irradiation time.

この溝加工によって、可動部３の上下には、固定部２側から可動部３側に沿って延びる上下の各ストッパ２３，２４がそれぞれ形成され、可動部３の上面と上ストッパ２３の下面との間、及び、可動部３の下面と下ストッパ２４との間には、それぞれ微小のストッパ用隙間ｇが形成される。 By this groove processing, upper and lower stoppers 23 and 24 extending from the fixed part 2 side along the movable part 3 side are formed above and below the movable part 3, respectively. And a small stopper gap g is formed between the lower surface of the movable portion 3 and the lower stopper 24.

このストッパ用隙間ｇは、固定部２側の各起歪部４ｂ，５ｂ等の発生応力に影響を与えないように、前記各起歪部４ｂ，５ｂ等よりも固定部２側へ十分延びている。 The stopper gap g extends sufficiently to the fixed portion 2 side than the strain generating portions 4b and 5b so as not to affect the generated stress of the strain generating portions 4b and 5b on the fixed portion 2 side. Yes.

可動部３の上面と上部貫通円孔７，８との距離ｅ、及び、可動部３の下面と下部貫通円孔９，１０との距離ｅは、等しく、起歪部４ａ，４ｂ；５ａ，５ｂが、ロードセル１ａの定格荷重に対して所定の撓み量を発生するのに必要な距離となっている。 The distance e between the upper surface of the movable part 3 and the upper through-holes 7 and 8 and the distance e between the lower surface of the movable part 3 and the lower through-holes 9 and 10 are equal, and the strain generating parts 4a, 4b; 5b is a distance required to generate a predetermined amount of deflection with respect to the load rating of the load cell 1a.

各ストッパ２３，２４の肉厚ｆは、ロードセル１ａの可動部３に定格荷重に比べて十分大きな許容される最大の負荷荷重が加わることによって、可動部３がストッパ２３，２４に当接して可動部３から定格荷重以上の力を受けても、可動部３の変位量が極めて小さくなるような厚みに設定される。 The thickness f of each of the stoppers 23 and 24 is such that the movable part 3 comes into contact with the stoppers 23 and 24 when the movable part 3 of the load cell 1a is subjected to a maximum allowable load that is sufficiently larger than the rated load. Even when a force greater than the rated load is received from the portion 3, the thickness is set such that the displacement amount of the movable portion 3 becomes extremely small.

ストッパ用隙間ｇの大きさ、すなわち、溝幅は、ロードセル１ａに定格荷重を負荷した場合に、可動部３に生じる変位量の、例えば１５０％を見込んだ変位量が１００ミクロンであるとすると、所定の過大負荷荷重による可動部３の変位量に相当する１００ミクロン前後のワイヤを使用し、ワイヤーカット放電加工を行うことによって、ストッパ用隙間ｇ＝１００ミクロンの溝を形成することができる。 The size of the stopper gap g, that is, the groove width, is assumed that the displacement amount, for example, 150% of the displacement amount generated in the movable part 3 when the rated load is applied to the load cell 1a is 100 microns. A groove with a stopper gap g = 100 microns can be formed by performing wire-cut electric discharge machining using a wire of about 100 microns corresponding to the displacement of the movable part 3 due to a predetermined excessive load.

ストッパ２３，２４が設けられたロードセル１ａでは、荷重受け台１４を取付けるための取付け部１４ａは、仮想線で示すように、可動部３の取付け面３ａのねじ孔１５ａ，１５ｂによってねじ止めされ、荷重受け台１４にかかる荷重によって可動部３が変位できるように構成される。 In the load cell 1a provided with the stoppers 23 and 24, the attachment portion 14a for attaching the load receiving base 14 is screwed by the screw holes 15a and 15b of the attachment surface 3a of the movable portion 3, as shown by phantom lines, The movable portion 3 can be displaced by a load applied to the load receiving base 14.

荷重受け台１４に大きな荷重が作用すると、可動部３の変位量が大きくなり、上記ストッパ用隙間ｇ以上になると、可動部３の下面が、下ストッパ２４の上面に当接し、可動部３の変位が制限され、過負荷によるロードセル１ａの破損を防止することができる。 When a large load is applied to the load receiving base 14, the amount of displacement of the movable portion 3 increases, and when the distance is greater than or equal to the above-described stopper gap g, the lower surface of the movable portion 3 comes into contact with the upper surface of the lower stopper 24. Displacement is limited and damage to the load cell 1a due to overload can be prevented.

また、可動部３が、逆方向に過剰に変位した場合に、同様に上ストッパ２３によって可動部３の変位が制限される。 Further, when the movable part 3 is excessively displaced in the reverse direction, the displacement of the movable part 3 is similarly limited by the upper stopper 23.

その他の構成は、上述の実施形態と同様である。 Other configurations are the same as those of the above-described embodiment.

(実施形態３)
図６は、本発明の他の実施形態のロードセル１ｂの正面図であり、図７は、その平面図であり、上述の実施形態に対応する部分には、同一の参照符号を付す。 (Embodiment 3)
FIG. 6 is a front view of a load cell 1b according to another embodiment of the present invention. FIG. 7 is a plan view of the load cell 1b. Components corresponding to those of the above-described embodiment are denoted by the same reference numerals.

上述の図１に示すように、可動部３の二つのねじ孔１５ａ，１５ｂには、荷重受け台１４がねじによって締付け固定される一方、固定部２の二つのねじ孔１３ａ，１３ｂには、基台１２がねじによって締付け固定される。 As shown in FIG. 1 described above, the load receiving base 14 is fastened and fixed to the two screw holes 15a and 15b of the movable portion 3 by screws, while the two screw holes 13a and 13b of the fixed portion 2 are fixed to the two screw holes 15a and 15b. The base 12 is fastened and fixed by screws.

この実施形態では、ねじ部の締付け応力が、円筒部６の周囲の起歪部１８ａａ〜１８ｄ等に与える影響を抑制しつつ、ロードセル１ｂを小型化するために、荷重受け台１４が取付けられる可動部３の二つのねじ孔１５ａ，１５ｂの各先端部と円筒部６との間には、前後方向に貫通する２つの貫通孔２５，２６が形成される一方、基台１２に取付けられる固定部２の一方のねじ孔１３ａと円筒部６との間には、前後方向に貫通する貫通孔２７が形成される。 In this embodiment, in order to reduce the size of the load cell 1b while suppressing the influence of the tightening stress of the screw portion on the strain-generating portions 18aa to 18d around the cylindrical portion 6, the movable base to which the load cradle 14 is attached is attached. Two through holes 25, 26 penetrating in the front-rear direction are formed between the tip ends of the two screw holes 15 a, 15 b of the part 3 and the cylindrical part 6, while the fixing part attached to the base 12 A through hole 27 penetrating in the front-rear direction is formed between one of the two screw holes 13 a and the cylindrical portion 6.

このようにねじ孔１５ａ，１５ｂの各先端部と円筒部６との間に、２つの貫通孔２５，２６を形成することによって、ねじ孔１５ａ，１５ｂの締付け応力が円筒部６の周囲の起歪部１８ａ，１８ｃ等に与える影響を抑制することができ、これによって、円筒部６と可動部３の取付け面３ａとの間の距離を短くできる。 In this way, by forming the two through holes 25 and 26 between the tip portions of the screw holes 15 a and 15 b and the cylindrical portion 6, the tightening stress of the screw holes 15 a and 15 b is generated around the cylindrical portion 6. The influence on the distorted portions 18a, 18c, etc. can be suppressed, whereby the distance between the cylindrical portion 6 and the mounting surface 3a of the movable portion 3 can be shortened.

また、固定部２の円筒部６寄りのねじ孔１３ａと円筒部６との間に、貫通孔２７を形成することによって、ねじ孔１３ａの締付け応力が円筒部６の周囲の起歪部１８ｄ等に与える影響を抑制することができ、これによって、円筒部６と固定部２の端面２ａとの距離を短くすることができる。 Further, by forming a through-hole 27 between the screw hole 13a near the cylindrical part 6 of the fixed part 2 and the cylindrical part 6, the tightening stress of the screw hole 13a causes the strain generating part 18d around the cylindrical part 6 and the like. Thus, the distance between the cylindrical portion 6 and the end surface 2a of the fixed portion 2 can be shortened.

このように円形の貫通孔２５，２６，２７を形成することによって、円筒部６と可動部３の取付け面３ａとの距離、及び、円筒部６と固定部２の端面２ａとの距離を短くできるので、ロードセル１ｂの左右方向の長さを短くして小型化することができる。 By forming the circular through holes 25, 26, 27 in this way, the distance between the cylindrical portion 6 and the mounting surface 3 a of the movable portion 3 and the distance between the cylindrical portion 6 and the end surface 2 a of the fixed portion 2 are shortened. Therefore, the load cell 1b can be reduced in size by reducing the length in the left-right direction.

（実施形態４）
図８は、本発明の更に他の実施形態のロードセル１ｃの正面図であり、図９は、図８のＡ−Ａ線に沿う断面図であり、上述の実施形態に対応する部分には、同一の参照符号を付す。 (Embodiment 4)
FIG. 8 is a front view of a load cell 1c according to still another embodiment of the present invention, and FIG. 9 is a cross-sectional view taken along the line AA in FIG. 8. In the portion corresponding to the above-described embodiment, The same reference numerals are attached.

この実施形態のロードセル１ｃは、防水仕様であり、円筒部６の内周面に貼着された歪ゲージ１９ａ〜１９ｄ部分に、完全な金属防水シールを施すため、両端部がやや大径の円筒形の金属製の密閉カバー２８を、円筒部６の内周面に嵌め込み、密閉カバー２８の両端部と円筒部６の内周面とを溶接によって接合している。これによって、歪ゲージ１９ａ〜１９ｄが貼着された部分は、外気から完全に密閉された空間となる。 The load cell 1c of this embodiment is waterproof, and since a complete metal waterproof seal is applied to the strain gauges 19a to 19d attached to the inner peripheral surface of the cylindrical portion 6, both ends are slightly large-diameter cylinders. A metal-made hermetic cover 28 is fitted into the inner peripheral surface of the cylindrical portion 6, and both end portions of the hermetic cover 28 and the inner peripheral surface of the cylindrical portion 6 are joined by welding. As a result, the portions to which the strain gauges 19a to 19d are attached become spaces that are completely sealed from the outside air.

収納室１１も上面の円形の開口部には、外周部にフランジの付いた薄い金属蓋２９を設けて覆い、開口部の周縁と金属蓋２９のフランジとを溶接し、完全密閉され防水性能の高い収納室１１となっている。 The storage chamber 11 is also covered with a thin metal lid 29 with a flange on the outer periphery of the circular opening on the upper surface, and the peripheral edge of the opening and the flange of the metal lid 29 are welded to be completely sealed and waterproof. The storage room 11 is high.

また、固定部２の接続孔２２には、防水コネクタが取付けられ、防水コネクタを介してロードセル１ｃの内部と外部機器（図示しない）とが接続される。 In addition, a waterproof connector is attached to the connection hole 22 of the fixed portion 2, and the inside of the load cell 1c and an external device (not shown) are connected via the waterproof connector.

（その他の実施形態）
上述の各実施形態では、各一対の上部貫通円孔７，８及び下部貫通円孔９，１０は、いずれもその一部が重なり合うように形成されたけれども、本発明の他の実施形態として、例えば、図１０に示すように、各一対の上部貫通円孔７，８及び下部貫通円孔９，１０は、重なり合うことなく、それぞれ近接して薄肉部２３ａ，２３ｂを残して形成してもよい。この場合、各一対の貫通円孔７，８及び貫通円孔９，１０は、当該ロードセル１ｄが所定の負荷荷重によってＳ字変形し、それぞれの起歪部が所定の大きさに歪むように、すなわち、歪検出部の応力に影響しない距離以内に近接して形成される。 (Other embodiments)
In each of the above-described embodiments, each of the pair of upper through-holes 7 and 8 and the lower through-holes 9 and 10 is formed so as to partially overlap, but as another embodiment of the present invention, For example, as shown in FIG. 10, each pair of upper through-holes 7 and 8 and lower through-holes 9 and 10 may be formed close to each other, leaving thin portions 23a and 23b. . In this case, the pair of through-holes 7 and 8 and the through-holes 9 and 10 are formed so that the load cell 1d is deformed into an S shape by a predetermined load, and the respective strain generating portions are distorted to a predetermined size. , They are formed close to each other within a distance that does not affect the stress of the strain detector.

上述の各実施形態では、上部及び下部の貫通円孔７，８；９，１０の直径は、円筒部６の内径よりも小さかったけれども、例えば、図１１に示すように、上部及び下部の貫通円孔７ａ，８ａ；９ａ，１０ａの直径を、円筒部６の内径以上の大きさとしてもよい。 In each of the above-described embodiments, the diameters of the upper and lower through holes 7, 8; 9, 10 are smaller than the inner diameter of the cylindrical portion 6. For example, as shown in FIG. The diameters of the circular holes 7a, 8a; 9a, 10a may be larger than the inner diameter of the cylindrical portion 6.

また、上部及び下部の貫通円孔７，８；９，１０は、円形に限らず、例えば、楕円形等の貫通孔としてもよい。 Further, the upper and lower through-holes 7, 8; 9, 10 are not limited to a circular shape, and may be, for example, elliptical through-holes.

上記各実施形態の構成を適宜組合せる、例えば、図１０のロードセルを、図８の防水仕様にしたり、図６のロードセルに、図４のストッパを設けるといったようにしてもよいのは勿論である。 Of course, the configuration of each of the above embodiments may be combined as appropriate, for example, the load cell of FIG. 10 may have the waterproof specification of FIG. 8, or the load cell of FIG. 6 may be provided with the stopper of FIG. .

１，１ａ〜1ｅロードセル
２固定部
３可動部
４上ビーム部
５下ビーム部
６円筒部
７，８上部貫通円孔
９，１０下部貫通円孔
１１収納室
１８連結部
２３，２４ストッパ
２５〜２７貫通孔
２８密閉カバー DESCRIPTION OF SYMBOLS 1,1a-1e Load cell 2 Fixed part 3 Movable part 4 Upper beam part 5 Lower beam part 6 Cylindrical part 7,8 Upper through-hole 9,10 Lower through-hole 11 Storage chamber 18 Connection part 23,24 Stopper 25-27 Through hole 28 Sealing cover

Claims

A fixed portion on one end side in the left-right direction and a movable portion on the other end side, and a pair of upper and lower beam portions that respectively connect the upper portion and the lower portion of the fixed portion and the movable portion,
A cylindrical portion extending in the front-rear direction is provided between the beam portions and between the fixed portion and the movable portion, and the outer periphery of the cylindrical portion is connected in part in the front-rear direction. Connected to the fixed part and the movable part via a part,
A pair of upper through-holes penetrating in the front-rear direction is formed on the upper beam portion side so as to be close or partially overlapped, while a pair of lower through-holes penetrating in the front-rear direction is formed on the lower beam portion side. The holes are formed close or partially overlapping,
Due to the pair of upper through-holes, the upper beam portion is formed with two strain-generating portions, while the connecting portion on the outer periphery of the cylindrical portion is formed with two strain-generating portions,
Due to the pair of lower through-holes, the lower beam part is formed with two strain generating parts, while the connecting part on the outer periphery of the cylindrical part is formed with two strain generating parts.
A load cell characterized by that.

The cylindrical part is connected to the fixed part and the movable part via the connecting part at the outer periphery in the center part in the front-rear direction,
The pair of upper through-holes and the pair of lower through-holes are through-holes having a diameter smaller than the inner diameter of the cylindrical portion, and the pair of through-holes are overlapped with each other in the left-right direction. Formed along the
The load cell according to claim 1.

A stopper that abuts on the movable portion that is displaced by a load and regulates the displacement of the movable portion is formed extending from the fixed portion side to the movable portion side,
The movable portion and the stopper each have opposing surfaces facing each other, and a stopper gap is formed between the opposing surfaces.
The load cell according to claim 1 or 2.

An attachment hole for attaching a cradle to the movable part is formed in the movable part, and a through hole penetrating in the front-rear direction is formed between the attachment hole and the outer periphery of the cylindrical part.
The load cell according to any one of claims 1 to 3.