阅读说明：本技术 力觉传感器和应变体 (Force sensor and strain body ) 是由 向井优 由井夏树 牧野泰育 小林岳久见 于 2020-03-27 设计创作，主要内容包括：本发明实现了一种力觉传感器,其能够将与应变计连接的电极或元件等适当地安装于应变体。力觉传感器(1)包括：具有因外力而变形的臂部(113a)的应变体(11),以及安装于臂部(113a)的应变计(12a1～12a4)。应变体(11)设置有从臂部(113a)朝向与臂部(113a)的长度方向交叉的方向突出的突出部(116a1、116a2)。(The invention realizes a force sensor which can properly mount an electrode, an element or the like connected to a strain gauge on a strain body. The force sensor (1) comprises: the strain gauge comprises a strain body (11) having an arm (113a) that deforms by an external force, and strain gauges (12a 1-12 a4) attached to the arm (113 a). The strain body (11) is provided with protrusions (116a1, 116a2) that protrude from the arm (113a) in a direction that intersects the longitudinal direction of the arm (113 a).)

1. A force sensor is characterized in that,

the force sensor includes a strain body having a deformation portion that deforms by an external force, and a strain gauge attached to the deformation portion,

the strain body has a protruding portion protruding from the deformation portion in a direction intersecting the longitudinal direction of the deformation portion.

2. The force sensor according to claim 1,

the strain body has: a core, a frame portion surrounding the core and including a flexure, and an arm portion connecting the core and the flexure;

the deformation portion is one or both of the arm portion and the flexure.

3. The force sensor according to claim 1,

the strain body has: a core, a frame portion surrounding the core, and an arm portion connecting the core and the frame portion;

the deformation portion is the arm portion.

4. The force sensor according to any one of claims 1 to 3, wherein the protrusion is mounted with an electrode or a resistive element connected to the strain gauge.

5. The force sensor according to claim 1,

the protrusion having a neck and a head, the head having a width wider than the neck,

one end of the neck portion is connected with the deformation portion, and the other end of the neck portion is connected with the head portion.

6. The force sensor according to claim 1,

the width of the joint between the protruding portion and the deformed portion is 1/2 or less of the length of the deformed portion.

7. A strain body is characterized in that,

the strain body has a deformation portion that deforms due to an external force,

the strain body has a protruding portion protruding from the deformation portion in a direction intersecting the longitudinal direction of the deformation portion.

Technical Field

The present invention relates to a force sensor. In particular, the present invention relates to a force sensor including a strain body having a deformation portion that deforms by an external force and a strain gauge attached to the deformation portion.

Background

A force sensor is known which includes a strain body having a deformation portion that deforms by an external force and a strain gauge attached to the deformation portion, and detects the external force using the strain gauge. For example, patent documents 1 to 2 disclose a 6-axis force sensor capable of detecting an x-axis direction component, a y-axis direction component, a z-axis direction component, a moment component around the x-axis, a moment component around the y-axis, and a moment component around the z-axis of an external force, respectively

[ Prior art documents ]

[ patent document ]

[ patent document 1 ] Japanese patent publication No. 6047703 "

[ patent document 2 ] Japanese patent publication No. 6378381 "

Disclosure of Invention

Problems to be solved by the invention

In the 6-axis force sensor described in patent documents 1 to 2, a strain gauge having the following structure is used: (1) a core (also referred to as a central portion or stressed portion); (2) a frame portion (also referred to as a frame portion or a fixing portion) that surrounds the core and includes a flexible member; (3) an arm portion connecting the core and the flexure. In the 6-axis force sensor, a plurality of strain gauges are attached to the arm portion and the flexure, and the arm portion and the flexure deform when an external force acts on the core portion, and the strain gauges are used to detect 6 components of the external force.

In such a force sensor, it is necessary to connect the strain gauges to each other by a wire or the like to form a bridge circuit. However, these strain gauges are provided on an arm portion, a flexure, and the like of an elongated structure. Therefore, the electrodes for connecting these strain gauges to the lead wires are dense, and as a result, the wiring work such as soldering becomes difficult.

In such a force sensor, a thin film resistor is mounted in the vicinity of the strain gauge in order to adjust the resistance balance in the bridge circuit. However, if an element whose characteristics change with deformation, such as sheet resistance, is attached to the arm or the flexure, the characteristics of the element change when an external force acts on the strain body, and as a result, there is a problem that the accuracy of the force sensor is lowered.

The present invention has been made in view of the above problems, and an object thereof is to realize a strain body capable of appropriately mounting an electrode or an element connected to a strain gauge, and a force sensor having such a strain body.

Means for solving the problems

A force sensor according to an embodiment of the present invention is a force sensor including a strain body having a deformation portion that deforms by an external force, and a strain gauge attached to the deformation portion, and is configured as follows. That is, the strain body has a protruding portion protruding from the deformation portion in a direction intersecting the longitudinal direction of the deformation portion.

A strain body according to an embodiment of the present invention is a strain body having a deformation portion that deforms by an external force, and has the following configuration, similar to the force sensor according to embodiment 1. That is, the strain body has a protruding portion protruding from the deformation portion in a direction intersecting the longitudinal direction of the deformation portion.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a force sensor in which an element connected to a strain gauge is appropriately attached to a strain body can be realized.

Drawings

Fig. 1 is a perspective view showing a structure of a strain body included in a force sensor according to an embodiment of the present invention.

Fig. 2 is a plan view showing a part of a front surface of the strain body of fig. 1.

Fig. 3 is a plan view showing a part of the back surface of the strain body of fig. 1.

Fig. 4 is a circuit diagram of a bridge circuit including strain gauges attached to the front inner peripheral side and the back inner peripheral side of the arm portion of the strain body of fig. 1.

Fig. 5 is a circuit diagram of a bridge circuit including strain gauges attached to the outer peripheral sides of the front and rear surfaces of the arm portion of the strain body of fig. 1.

Fig. 6 is a plan view showing the dimensions of each part of the strain body included in the force sensor according to the embodiment of the present invention.

Fig. 7 is a diagram showing the distribution of stress generated in the strain body of fig. 6 when an external force in the positive x-axis direction acts on the core portion.

Fig. 8 is a diagram showing the distribution of stress generated in the strain body of fig. 6 when an external force in the positive y-axis direction acts on the core portion.

Fig. 9 is a diagram showing a distribution of stress generated in the strain body of fig. 6 when an external force in the positive z-axis direction acts on the core portion.

Fig. 10 is a diagram showing a distribution of stresses generated in the strain body of fig. 6 when a moment about the x-axis acts on the core portion.

Fig. 11 is a diagram showing a distribution of stresses generated in the strain body of fig. 6 when a moment about the y-axis acts on the core portion.

Fig. 12 is a diagram showing a distribution of stresses generated in the strain body of fig. 6 when a moment about the z-axis acts on the core portion.

Fig. 13 is a diagram showing the distribution of stresses generated in the strain body according to the comparative example when an external force in the positive x-axis direction acts on the core portion.

Fig. 14 is a diagram showing the distribution of stress generated in the strain body according to the comparative example when an external force in the positive y-axis direction acts on the core portion.

Fig. 15 is a diagram showing the distribution of stress generated in the strain body according to the comparative example when an external force in the positive z-axis direction acts on the core portion.

Fig. 16 is a diagram showing the distribution of stresses generated in the strain body according to the comparative example when a moment about the x-axis acts on the core portion.

Fig. 17 is a diagram showing the distribution of stresses generated in the strain body according to the comparative example when a moment about the y-axis acts on the core portion.

Fig. 18 is a diagram showing the distribution of stresses generated in the strain body according to the comparative example when a moment about the z-axis acts on the core portion.

Fig. 19 is a diagram showing a distribution of stresses generated in the arm portion of the strain body according to the comparative example.

Fig. 20 is a diagram showing the distribution of stress generated in the arm portion in the strain body of fig. 6 having the joint width W of 0.5 mm.

Fig. 21 is a diagram showing the distribution of stress generated in the arm portion in the strain body of fig. 6 having the joint width W of 1.0 mm.

Fig. 22 is a diagram showing the distribution of stress generated in the arm portion in the strain body of fig. 6 having the joint width W of 1.5 mm.

Fig. 23 is a diagram showing the distribution of stress generated in the arm portion in the strain body of fig. 6 having the joint width W of 2.0 mm.

Fig. 24 is a diagram showing the distribution of stress generated in the arm portion in the strain body of fig. 6 having the joint width W of 2.5 mm.

Fig. 25 is a diagram showing the distribution of stress generated in the arm portion in the strain body of fig. 6 having the joint width W of 3.0 mm.

Fig. 26 is a diagram showing the distribution of stress generated in the arm portion in the strain body of fig. 6 having the joint width W of 3.5 mm.

Fig. 27 is a diagram showing the distribution of stress generated in the arm portion in the strain body of fig. 6 having the joint width W of 4.0 mm.

Fig. 28 is a plan view and a side view showing a first configuration example of the resistance element.

Fig. 29 is a plan view and a side view showing a first configuration example of the resistance element.

Fig. 30 is a plan view and a side view showing a second configuration example of the resistance element.

Fig. 31 is a plan view and a side view showing a second configuration example of the resistance element.

Fig. 32 is a plan view showing a third configuration example of the resistance element before adjustment.

Fig. 33 is a plan view showing a third configuration example of the resistance element after adjustment.

Fig. 34 is a plan view showing a fourth configuration example of the resistance element before adjustment.

Fig. 35 is a plan view showing a fourth configuration example of the resistance element after adjustment.

Fig. 36 is a plan view showing a fifth configuration example of the resistance element before adjustment.

Fig. 37 is a plan view showing a fifth configuration example of the resistance element after adjustment.

Fig. 38 is a plan view showing a sixth configuration example of the resistance element before adjustment.

Fig. 39 is a plan view showing a sixth configuration example of the resistance element after adjustment.

Detailed Description

Structure of force sensor

The structure of the force sensor 1 according to one embodiment of the present invention will be described with reference to fig. 1 to 5.

The force sensor 1 is a 6-axis force sensor, and includes: a strain body 11; a strain gauge group 12 composed of 24 strain gauges; an electrode group 13 composed of 48 electrodes; a resistance element group 14 composed of 24 resistance elements; and a bridge circuit group 15 composed of 6 bridge circuits. Here, the 6-axis force sensor is a force sensor capable of detecting an x-axis direction component, a y-axis direction component, a z-axis direction component, a moment component around the x-axis, a moment component around the y-axis, and a moment component around the z-axis of an external force. In addition, the strain body 11 is arranged such that the two main surfaces are parallel to the xy plane, and the main surface on the z-axis positive direction side of the strain body 11 is referred to as "front surface", and the main surface on the z-axis negative direction side of the strain body 11 is referred to as "back surface".

Fig. 1 is a perspective view of a strain body 11 included in a force sensor 1. The strain body 11 is a structure made of an elastic material, and as shown in fig. 1, includes a core 111, a frame 112 surrounding the core 111, and arm portions 113a to 113c connecting the core 111 and the frame 112. Examples of the material of the strain body 11 include aluminum alloy, alloy steel, and stainless steel. Further, as a method of processing the strain body 11, for example, NC (Numerical Control) processing and the like can be cited. When an external force acts on the core 111 in a state where the frame portion 112 is fixed, strain corresponding to the external force is generated in the arm portions 113a to 113 c. Therefore, the core 111 may also be referred to as a "force receiving portion", and the frame portion 112 may also be referred to as a "fixing portion".

The shape of the core 111 is not particularly limited, but in the present embodiment, the shape of the core 111 is a columnar shape having a substantially hexagonal bottom surface (i.e., a substantially hexagonal prism shape). The shape of the frame portion 112 is not particularly limited, but in the present embodiment, the shape of the frame portion 112 is a cylindrical shape having a bottom surface hollowed out in a substantially circular shape to form a substantially hexagonal shape. The core 111 is accommodated in the frame portion 112 such that 6 side surfaces 111a to 111f of the core 111 are opposed to 6 inner side surfaces 112a to 112f of the frame portion 112, respectively.

The shape of the arm portions 113a to 113c is not particularly limited, but in the present embodiment, a columnar shape having a substantially rectangular bottom surface (i.e., a substantially quadrangular prism shape) is used as the shape of the arm portions 113a to 113 c. The number of arm portions 113a to 113c is not particularly limited, but in the present embodiment, the number of arm portions 113a to 113c is 3. The arm portion 113a extends from the core portion 111 in the negative y-axis direction in the xy plane, and connects the side surface 111a of the core portion 111 and the inner side surface 112a of the frame portion 112. Further, the arm portion 113b extends from the core portion 111 in the xy plane from the v-axis negative direction toward a direction of-120 ° (120 ° clockwise), and connects the side surface 111b of the core portion 111 and the inner side surface 112b of the frame portion 112. Further, the arm portion 113c extends from the core portion 111 in the xy plane from the y-axis negative direction to a direction of +120 ° (counterclockwise direction 120 °), and connects the side surface 111c of the core portion 111 and the inner side surface 112c of the frame portion 112.

The frame portion 112 has through holes 114a to 114c penetrating the frame portion 112 in the z-axis direction. The through hole 114a is formed near the connection point between the arm portion 113a and the frame portion 112, and the longitudinal direction of the through hole 114a is orthogonal to the extending direction of the arm portion 113 a. The through hole 114b is formed near the connection point between the arm portion 113b and the frame portion 112, and the longitudinal direction of the through hole 114b is orthogonal to the extending direction of the arm portion 113 b. The through hole 114c is formed near the connection point between the arm portion 113c and the frame portion 112, and the longitudinal direction of the through hole 114c is orthogonal to the extending direction of the arm portion 113 c. Therefore, strain corresponding to the external force can be generated in the arm portions 113a to 113 c.

Hereinafter, a region of the frame portion 112 connected to the arm portion 113a on the inner peripheral side of the through hole 114a is referred to as a flexure 115 a. A region of the frame portion 112 connected to the arm portion 113b on the inner peripheral side of the through hole 114b is referred to as a flexure 115 b. A region of the frame portion 112 connected to the arm portion 113c on the inner peripheral side of the through hole 114c is referred to as a flexure 115 c.

Fig. 2 is a plan view showing a part of the front surface of the arm portion 113a (inside the circumference α shown in fig. 1). As shown in fig. 2, 4 strain gauges 12a1 to 12a4 are attached to the front surface of arm portion 113 a. For example, strain gauges 12a1 to 12a4 may be formed of a conductor thin film (e.g., a metal thin film such as a Cu — Ni base alloy thin film or a Ni — Cr base alloy thin film) or a semiconductor thin film covered with an insulator film (e.g., a resin film such as a polyimide film or an epoxy film). Examples of the method of attaching strain gauges 12a1 to 12a4 include an adhesive method, a vacuum deposition method, and a sputtering method.

Of the 4 strain gauges 12a1 to 12a4, 2 strain gauges 12a1 and 12a2 on the front surface inner peripheral side (core portion 111 side) are arranged in the xy plane such that the longitudinal direction is parallel to the extending direction of the arm portion 113 a. On the other hand, the 2 strain gauges 12a3, 12a4 on the front outer peripheral side (frame portion 112 side) are arranged such that the longitudinal direction forms 45 ° with the extending direction of the arm portion 113a in the xy plane.

Two electrodes 13a1, 13a2 are connected to strain gauge 12 al. Resistor element 14a1 is inserted into a wiring between gauge 12a1 and electrode 13a2 (insertion of a resistor element into a wiring between a and B means that the wiring is divided into a side a and B, one end of the resistor element is connected to the wiring on the a side, and the other end of the resistor element is connected to the wiring on the B side. In addition, two electrodes 13a3, 13a4 are connected to strain gauge 12a 2. A resistance element 14a2 is inserted at a wiring between the strain gauge 12a2 and the electrode 13a 4. In addition, two electrodes 13a5, 13a6 are connected to strain gauge 12a 3. A resistance element 14a3 is inserted at a wiring between the strain gauge 12a3 and the electrode 13a 5. In addition, two electrodes 13a7, 13a8 are connected to strain gauge 12a 4. A resistance element 14a4 is inserted at a wiring between the strain gauge 12a4 and the electrode 13a 7. Therefore, 8 electrodes 13a1 to 13a8 and 4 resistance elements 14a1 to 14a4 are attached to the front surface of arm 113a in addition to 4 strain gauges 12a1 to 12a 4. Examples of the mounting method of the electrodes 13a1 to 13a8, the resistor elements 14a1 to 14a4, and the wiring pattern connecting them include sputtering.

Fig. 3 is a plan view showing a part of the back surface of the arm portion 113a (inside the circumference β shown in fig. 1). As shown in fig. 3, 4 strain gauges 12a5 to 12a8 are attached to the rear surface of arm 113 a. As for strain gauges 12a5 to 12a8, similar to strain gauges 12a1 to 12a4, for example, a conductor film or a semiconductor film covered with an insulator film may be used. The method of mounting strain gauges 12a5 to 12a8 includes an adhesive method, a vacuum deposition method, a sputtering method, and the like, as in the case of the method of mounting strain gauges 12a1 to 12a 4.

Of the 4 strain gauges 12a5 to 12a8, 2 strain gauges 12a5 and 12a6 on the inner peripheral side of the back surface are mounted in the xy plane so that the longitudinal direction is parallel to the extending direction of the arm portion 113a, and form a bridge circuit together with 2 strain gauges 12a1 and 12a2 mounted on the inner peripheral side of the front surface. On the other hand, the 2 gauge gauges 12a7, 12a8 on the outer periphery of the back surface are mounted on the xy plane such that the longitudinal direction thereof forms 45 ° with the extending direction of the arm portion 113a, and form a bridge circuit together with the 2 gauge gauges 12a3, 12a4 mounted on the outer periphery of the front surface.

Two electrodes 13a9, 13a10 are connected to strain gauge 12a 5. A resistance element 14a5 is inserted at a wiring between the strain gauge 12a5 and the electrode 13a 10. In addition, two electrodes 13a11, 13a12 are connected to strain gauge 12a 6. A resistance element 14a6 is inserted at a wiring between the strain gauge 12a6 and the electrode 13a 12. In addition, two electrodes 13a13, 13a14 are connected to strain gauge 12a 7. A resistance element 14a7 is inserted at a wiring between the strain gauge 12a7 and the electrode 13a 13. In addition, two electrodes 13a15, 13a16 are connected to strain gauge 12a 8. A resistance element 14a8 is inserted at a wiring between the strain gauge 12a8 and the electrode 13a 15. Therefore, 8 electrodes 13a9 to 13a16 and 4 resistance elements 14a5 to 14a8 are attached to the back surface of arm 113a in addition to 4 strain gauges 12a5 to 12a 8. Examples of the mounting method of the electrodes 13a9 to 13a16, the resistor elements 14a5 to 14a8, and the wiring pattern for connecting them include sputtering.

Thus, the arm portion 113a is provided with 4 strain gauges, 8 electrodes, and 4 resistance elements on the front and back surfaces, respectively. The arm portion 113b is also provided with 4 strain gauges, 8 electrodes, and 4 resistance elements on the front and back surfaces, respectively, as with the arm portion 113 a. Further, the arm portion 113c is also provided with 4 strain gauges, 8 electrodes, and 4 resistance elements on the front and back surfaces, respectively, as with the arm portion 113 a. Therefore, the strain body 11 includes 24 strain gauges in total, 48 electrodes in total, and 24 resistance elements in total. The strain gauge group 12 is a set of the 24 strain gauges, the electrode group 13 is a set of the 48 electrodes, and the resistance element group 14 is a set of the 24 resistance elements.

Fig. 4 is a circuit diagram of bridge circuit 15a1, and bridge circuit 15a1 includes 2 strain gauges 12a1 and 12a2 attached to the front inner peripheral side of arm portion 113a and 2 strain gauges 12a5 and 12a6 attached to the back inner peripheral side of arm portion 113 a. The bridge circuit 15a1 is realized by connecting the following electrodes with a wire or the like.

Electrodes 13a1 of strain gauge 12a1 and electrodes 13a11 of strain gauge 12a 6;

electrodes 13a3 of strain gauge 12a2 and electrodes 13a9 of strain gauge 12a 5;

electrodes 13a2 of strain gauge 12a1 and electrodes 13a10 of strain gauge 12a 5;

the electrodes 13a4 of strain gauge 12a2 and the electrodes 13a12 of strain gauge 12a 6.

In the bridge circuit 15a1, as shown in fig. 4, a reference voltage V is applied between points a and B_DatumThe voltage Vo between the points C and D at that time becomes the output voltage. Here, point a is a middle point between electrode 13a1 of strain gauge 12a1 and electrode 13a11 of strain gauge 12a 6. Further, point B refers to an intermediate point between electrode 13a3 of strain gauge 12a2 and electrode 13a9 of strain gauge 12a 5. Further, point C is a middle point between electrode 13a2 of strain gauge 12a1 and electrode 13a10 of strain gauge 12a 5. Note that point D is a point intermediate between electrode 13a4 of strain gauge 12a2 and electrode 13a12 of strain gauge 12a 6. The resistance elements 14a1, 14a2, 14a5, and 14a6 included in the bridge circuit 15a1 are used for adjustment of the resistance balance of the bridge circuit 15a 1.

Fig. 5 is a circuit diagram of bridge circuit 15a2, and bridge circuit 15a2 includes 2 strain gauges 12a3 and 12a4 attached to the outer periphery of the front surface of arm 113a and 2 strain gauges 12a7 and 12a8 attached to the outer periphery of the back surface of arm 113 a. The bridge circuit 15a2 is realized by connecting the following electrodes with a wire or the like.

Electrodes 13a5 of strain gauge 12a3 and electrodes 13a15 of strain gauge 12a 8;

electrodes 13a7 of strain gauge 12a4 and electrodes 13a13 of strain gauge 12a 7;

electrodes 13a14 of strain gauge 12a7 and electrodes 13a16 of strain gauge 12a 8;

the electrodes 13a6 of strain gauge 12a3 and the electrodes 13a8 of strain gauge 12a 4.

In the bridge circuit 15a2, as shown in fig. 5, a reference voltage V is applied between points E and F_DatumThe voltage Vo between the G point and the H point at that time is the output voltage. Here, point E refers to an intermediate point between electrode 13a5 of strain gauge 12a3 and electrode 13a15 of strain gauge 12a 8. Further, point F is a middle point between electrode 13a7 of strain gauge 12a4 and electrode 13a13 of strain gauge 12a 7. Further, the G point is a middle point between the electrode 13a14 of the strain gauge 12a7 and the electrode 13a16 of the strain gauge 12a 8. Note that point H is a point intermediate between electrode 13a6 of strain gauge 12a3 and electrode 13a8 of strain gauge 12a 4. The resistance elements 14a3, 14a4, 14a7, and 14a8 included in the bridge circuit 15a2 are used for adjustment of the resistance balance of the bridge circuit 15a 2.

In this way, the 4 strain gauges, the 8 electrodes, and the 4 resistance elements provided to the arm portion 113a constitute two bridge circuits. The 4 strain gauges, 8 electrodes, and 4 resistance elements provided in the arm portion 113b also form two bridge circuits in the same manner as the 4 strain gauges, 8 electrodes, and 4 resistance elements provided in the arm portion 113 a. In addition, the 4 strain gauges, the 8 electrodes, and the 4 resistance elements provided in the arm portion 113c also constitute 2 bridge circuits in the same manner as the 4 strain gauges, the 8 electrodes, and the 4 resistance elements provided in the arm portion 113 a. Therefore, the straining body 11 includes a total of 6 bridge circuits. The bridge circuit group 15 refers to a set of these 6 bridge circuits. In addition, when it is not necessary to adjust the resistance balance in each bridge circuit constituting the bridge circuit group 15, the resistance element group 14 may be omitted.

Characteristics of force sensor

The features of the force sensor 1 are explained again with reference to fig. 1 to 3.

The force sensor 1 is characterized in that the strain body 11 has a protruding portion. The protruding portion is formed by: in the strain body 11, a portion that is deformed when an external force acts on the core portion 111 (hereinafter also referred to as a "deformed portion") protrudes toward a direction intersecting with a longitudinal direction of the deformed portion in the xy plane. Such a projection is adjacent to the deformation. Therefore, the space for mounting a part or all of the element (for example, one or both of the electrode and the resistive element) connected to the element (for example, the strain gauge) mounted on the deformation portion can be used as appropriate. Further, although such a protruding portion is adjacent to the deformed portion, it is less likely to be deformed than the deformed portion. Therefore, the space for mounting an element (for example, a resistance element) that is connected to an element (for example, a strain gauge) attached to the deformation portion and has a characteristic that changes with deformation can be used particularly suitably.

In the force sensor 1 according to the present embodiment, the portions corresponding to the deformation portions are the arm portions 113a to 113c and the flexible pieces 115a to 115 c. Therefore, as shown in fig. 1, the strain body 11 of the force sensor 1 of the present embodiment includes the protrusions 116a1 to 116c2 protruding from the arm portions 113a to 113c and the protrusions 117a1 to 117c4 protruding from the flexible pieces 115a to 115 c.

The projections 116a1, 116a2 projecting from the arm 113a will be described with reference to fig. 2 and 3.

The protruding portion 116a1 protrudes from the center of the arm portion 113a in the x-axis negative direction, and the protruding direction (x-axis negative direction) of the protruding portion 116a1 intersects (is orthogonal to) the longitudinal direction (y-axis direction) of the arm portion 113 a. The protruding portion 116a2 protrudes from the center of the arm portion 113a in the positive x-axis direction, and the protruding direction (positive x-axis direction) of the protruding portion 116a2 intersects (is orthogonal to) the longitudinal direction (y-axis direction) of the arm portion 113 a. Tabs 116a1, 116a2 have neck portions 116a11, 116a21 and head portions 116a12, 116a22, respectively. One ends of necks 116a11 and 116a21 are connected to arm 113a, respectively, and the other ends of necks 116a11 and 116a21 are connected to heads 116a12 and 116a22, respectively. The width of neck portions 116a11, 116a21 (width measured in the longitudinal direction of arm portion 113a) is narrower than the width of head portions 116a12, 116a22 (width measured in the longitudinal direction of arm portion 113 a). Therefore, even if the arm portions 113a are deformed, the projections 116a1, 116a2 (particularly the heads 116a12, 116a22) are less likely to be further deformed.

As shown in fig. 2, an electrode 13a2 and a resistive element 14a1 connected to strain gauge 12a1, and an electrode 13a5 and a resistive element 14a3 connected to strain gauge 12a3 are mounted on the front surface of protrusion 116a 1. Further, as shown in fig. 3, on the back surface of protrusion 116a1, electrode 13a12 and resistive element 14a6 connected to strain gauge 12a6, and electrode 13a15 and resistive element 14a8 connected to strain gauge 12a8 are mounted. On the other hand, as shown in fig. 2, electrode 13a4 and resistive element 14a2 connected to strain gauge 12a2, and electrode 13a7 and resistive element 14a4 connected to strain gauge 12a4 are mounted on the front surface of protrusion 116a 2. Further, as shown in fig. 3, on the back surface of protrusion 116a2, electrode 13a10 and resistive element 14a5 connected to strain gauge 12a5, and electrode 13a13 and resistive element 14a7 connected to strain gauge 12a7 are mounted.

In this way, in the force sensor 1 according to the present embodiment, part of the electrodes 13a1 to 13a16 can be attached to the protrusions 116a1 and 116a 2. Therefore, the density of the electrodes 13a 1-13 a16 is reduced. Therefore, the wiring work (for example, welding work) to the electrodes 13a1 to 13a16 can be facilitated. In the force sensor 1 according to the present embodiment, the resistive elements 14a1 to 14a8 can be attached to the protrusions 116a1 and 116a 2. Therefore, variations in the resistance values of the resistance elements 14a 1-14 a8 due to deformation of the arm portions 113a are suppressed. Therefore, the effect of suppressing the deterioration of the accuracy of the force sensor 1 due to the variation in the resistance values of the resistance elements 14a1 to 14a8 can be obtained.

The width (width measured in the longitudinal direction of the arm portion 113a) of the neck portions 116a11, 116a21 of the protrusions 116a1, 116a2 is preferably 1/2 or less of the length L of the arm portion 113 a.

The protrusions 117a 1-117 a4 protruding from the flexure 115a will be described with reference to FIGS. 2 and 3.

The protrusions 117a1, 117a2 are portions that protrude from the flexure 115a in the y-axis positive direction, and the protruding directions (y-axis positive directions) of the protrusions 117a1, 117a2 intersect (are orthogonal to) the longitudinal direction (x-axis direction) of the flexure 115 a. The projection starting point of the projection 117a1 is closer to the x-axis negative direction side than the arm portion 113a, and the projection starting point of the projection 117a2 is closer to the x-axis positive direction side than the arm portion 113 a. The tabs 117a1, 117a2 have necks 117a11, 117a21 and heads 117a12, 117a22, respectively. One end of the neck portions 117a11, 117a21 are connected to the flexure 115a, respectively, and the other end of the neck portions 117a11, 117a21 are connected to the head portions 117a12, 117a22, respectively. The neck 117a11, 117a21 is narrower in width than the head 117a12, 117a 22. Therefore, even if the flexure 115a is deformed, the protrusions 117a1, 117a2 (particularly the heads 117a12, 117a22) are difficult to be further deformed.

The protrusions 117a3, 117a4 are portions protruding from the flexure 115a in the y-axis negative direction, and the protruding direction (y-axis negative direction) of the protrusions 117a3, 117a4 intersects (is orthogonal to) the longitudinal direction (x-axis direction) of the flexure 115 a. The projection starting point of the projection 117a3 is closer to the x-axis negative direction side than the arm portion 113a, and the projection starting point of the projection 117a4 is closer to the x-axis positive direction side than the arm portion 113 a. The tabs 117a3, 117a4 have necks 117a31, 117a41 and heads 117a32, 117a42, respectively. One end of the neck portions 117a31, 117a41 are connected to the flexure 115a, respectively, and the other end of the neck portions 117a31, 117a41 are connected to the head portions 117a32, 117a42, respectively. The neck 117a31, 117a41 is narrower in width than the head 117a32, 117a 42. Therefore, even if the flexure 115a is deformed, the protrusions 117a3, 117a4 (particularly the heads 117a32, 117a42) are difficult to be further deformed.

A strain gauge may be attached to the flexure 115 a. In this case, a part of the electrode connected to the strain gauge may be attached to the projections 117a1 to 117a 4. In this case, the resistance elements connected to the strain gauges may be attached to the protrusions 117a1 to 117a 4. Therefore, the same effects as those obtained by providing the projections 116a1 and 116a2 on the arm portion 113a can be obtained by providing the projections 117a1 to 117a4 on the flexure 115 a.

In the present embodiment, the configuration is adopted in which the deformation portions provided with the protruding portions are both the arm portions 113a to 113c and the flexible pieces 115a to 115c, but the present invention is not limited to this. For example, the deformation portion provided with the protruding portion may be one of the arm portions 113a to 113c and the flexible pieces 115a to 115c, that is, only the arm portions 113a to 113c may be the deformation portion provided with the protruding portion, or only the flexible pieces 115a to 115c may be the deformation portion provided with the protruding portion. The flexible members 115a to 115c may be omitted. In this case, the only deformed portions provided with the protruding portions are the arm portions 113a to 113 c.

Distribution of stress generated in strain body

The distribution of the stress generated in the strain body when an external force acts on the core portion will be described with reference to fig. 6 to 27. Here, the results of the simulation using 3d cad are shown for a strain gauge of a force sensor (a Φ 55mm force sensor) having an outer diameter of 55mm in a plan view of a frame portion.

Fig. 6 is a plan view showing the dimensions of each part of the strain body as an example. The portion where the protrusion is omitted from the strain body is referred to as a comparative example.

Fig. 7 to 12 are diagrams each showing a stress distribution of the strain body according to the example. Fig. 7 shows the distribution of the stress generated in the straining body according to the embodiment when the external force Fx + toward the positive x-axis direction acts on the core portion. Fig. 8 shows the distribution of the stress generated in the straining body according to the embodiment when the external force Fy + toward the positive direction of the y-axis acts on the core portion. Fig. 9 shows the distribution of the stress generated in the straining body according to the embodiment when the external force Fz + toward the positive z-axis direction acts on the core portion. Fig. 10 shows the distribution of the stress generated in the strain body according to the embodiment when the moment Mx + about the x-axis acts on the core portion. Fig. 11 shows the distribution of the stress generated in the strain body according to the embodiment when the moment My + about the y-axis acts on the core portion. Fig. 12 shows the distribution of the stress generated in the strain body according to the embodiment when the moment Mz + about the z-axis acts on the core portion.

Fig. 13 to 18 are diagrams each showing a stress distribution of the strain body according to the comparative example. Fig. 13 shows the distribution of the stress generated in the strain body according to the comparative example when an external force Fx + in the positive x-axis direction acts on the core portion. Fig. 14 shows the distribution of the stress generated in the strain body according to the comparative example when the external force Fy + in the positive y-axis direction acts on the core portion. Fig. 15 shows the distribution of the stress generated in the strain body according to the comparative example when the external force Fz + in the positive z-axis direction acts on the core portion. Fig. 16 shows the distribution of the stress generated in the strain body according to the comparative example when the moment Mx + about the x-axis acts on the core portion. Fig. 17 shows the distribution of the stress generated in the strain body according to the comparative example when the moment My + about the y-axis acts on the core portion. Fig. 18 shows the distribution of the stress generated in the strain body according to the comparative example when the moment Mz + about the z-axis acts on the core portion.

Referring to fig. 7 to 12, the following results were confirmed. That is, no stress is generated in each protruding portion, or even if stress is generated, the stress is very small. This means that even if an external force acts on the core, the respective protruding portions are not deformed, or even if deformed, the deformation is very small. Thus, it was confirmed that the protruding portion was suitable as a space for mounting an element (e.g., a resistance element) whose characteristics changed with the deformation.

Further, the following results were confirmed by comparing fig. 7 to 12 and fig. 13 to 18. That is, even if the protruding portion is provided, the stress generated in the arm portion and the flexure does not change, or even if a change occurs, the amount of change is very small. Therefore, it can be confirmed that the accuracy of the force sensor is not lowered by the provision of the projection, or even if the lowering occurs, the amount of the lowering is very small.

Next, it was examined how the distribution of the stress generated in the arm portions when an external force Fx + in the positive x-axis direction acts on the core portion depends on the joint width W of the protruding portions and the arm portions (see fig. 6). Fig. 19 to 27 are diagrams showing the results. In the present embodiment, the protruding portion has a constricted portion, and when the constricted portion is engaged with the arm portion, the engagement width W is the width of the narrowest portion of the constricted portion.

Fig. 19 shows a distribution of stresses generated in the arm portion of the strain body according to the comparative example. Fig. 20 shows the distribution of the stress generated in the arm portion in the strain body according to the embodiment in which the joint width W is 0.5 mm. Fig. 21 shows the distribution of the stress generated in the arm portion in the strain body of the embodiment in which the joint width W is 1.0 mm. Fig. 22 shows the distribution of the stress generated in the arm portion in the strain body according to the embodiment having the joint width W of 1.5 mm. Fig. 23 shows the distribution of the stress generated in the arm portion in the strain body according to the embodiment having the joint width W of 2.0 mm. Fig. 24 shows the distribution of the stress generated in the arm portion in the strain body according to the embodiment in which the joint width W is 2.5 mm. Fig. 25 shows the distribution of the stress generated in the arm portion in the strain body according to the embodiment having the joint width W of 3.0 mm. Fig. 26 shows the distribution of the stress generated in the arm portion in the strain body according to the embodiment having the joint width W of 3.5 mm. Fig. 27 shows the distribution of the stress generated in the arm portion in the strain body according to the embodiment in which the joint width W is 4.0 mm. For the sake of simulation, in the strain body having the joining width W of 2.5mm or more, the width of the protrusion is made uniform without providing the neck portion having a narrow width and the head portion having a wide width in the protrusion.

Referring to fig. 19 to 27, the following results were confirmed. First, when the joint width W is 4.0mm or less, in other words, when the joint width W is 1/2 or less of the length L (8mm) of the arm portion, it can be confirmed that there is a portion where no stress is generated in the protrusion portion. Therefore, in the case of using the protruding portion as a space for mounting an element (e.g., a resistance element) whose characteristics change with deformation, the engagement width W of the arm portion and the protruding portion is preferably 1/2 or less of the length L of the arm portion. Second, in the case where the joint width W is 1.0mm or less, in other words, in the case where the joint width W is 1/8 or less of the length L (8mm) of the arm portion, it can be confirmed that the stress generated in the arm portion is hardly changed as compared with the case where there is no protrusion portion. Therefore, when the force sensor 1 is required to have extremely high accuracy, the joint width W of the arm portion and the projection is preferably 1/8 or less of the arm length L.

Example of the structure of the resistance element

A configuration example of each resistance element belonging to the resistance element group 14 will be described with reference to fig. 28 to 39.

Fig. 28 and 29 are a plan view and a side view respectively showing a first configuration example of the resistance element.

The resistor element according to the present configuration is constituted by a thin film resistor 21 having a quadrangular shape in plan view (rectangular shape in the illustrated example). The resistance value of the resistor element is adjusted by cutting the upper surface of the thin film resistor 21 to reduce the thickness of the thin film resistor 21. Fig. 28 shows the resistance element before trimming, and fig. 29 shows the resistance element after trimming. By this adjustment, the sectional area of the thin-film resistor 21 is reduced, and thus the resistance value is increased. Further, the degree to which the resistance value is increased can be appropriately adjusted by changing the thickness of the cut thin-film resistor 21.

Fig. 30 and 31 are a plan view and a side view respectively showing a second configuration example of the resistance element.

The resistor element according to the present configuration example is composed of the thin film resistors 21 each having a quadrangular shape in plan view (a rectangular shape in the illustrated example), similarly to the resistor element according to the first configuration example. The resistance value of the resistor element is adjusted by forming the conductor layer 22 on the thin-film resistor 21. Fig. 30 shows the resistance element before trimming, and fig. 31 shows the resistance element after trimming. By this adjustment, the effective length of the thin-film resistor 21 is reduced, and therefore the resistance value is lowered. Further, the degree of reduction of the resistance value can be appropriately adjusted by changing the length of the conductor layer 22.

Fig. 32 and 33 are plan views each showing a third configuration example of the resistance element.

The resistance element according to the present configuration example is configured by: (1) the first strip film conductor 24 a; (2) a second strip-shaped thin-film conductor 24b arranged in parallel with the first strip-shaped thin-film conductor 24 a; (3) and a plurality of strip-shaped thin-film resistors 25 each having one end connected to the first strip-shaped thin-film conductor 24a and the other end connected to the second strip-shaped thin-film conductor 24 b. The resistance value of the resistor element is adjusted by cutting the number of the strip-shaped thin-film resistors 25. Fig. 32 shows the resistance element before trimming, and fig. 33 shows the resistance element after trimming. By this adjustment, the number of strip-shaped thin-film resistors 25 interposed between the first strip-shaped thin-film conductor 24a and the second strip-shaped thin-film conductor 24b is reduced, and therefore the resistance value is increased. Further, the degree to which the resistance value is increased can be appropriately adjusted by changing the number of the strip-shaped thin-film resistors 25 to be cut.

Fig. 34 and 35 are plan views each showing a fourth configuration example of the resistance element.

The resistance element according to the present configuration example is configured by: (1) the first strip film conductor 24 a; (2) a second strip-shaped thin-film conductor 24b arranged in parallel with the first strip-shaped thin-film conductor 24 a; (3) a strip-shaped thin-film resistor 25 having one end connected to the first strip-shaped thin-film conductor 24a and the other end connected to the second strip-shaped thin-film conductor 24 b; (4) a plurality of strip-shaped thin-film resistors 26 having one end open and the other end connected to the second strip-shaped thin-film conductors 24 b. The resistance value of the resistor element is adjusted by the number of the strip-shaped thin-film resistors 26 connected to the first strip-shaped thin-film conductor 24a by welding or the like. Fig. 34 shows the resistance element before trimming, and fig. 35 shows the resistance element after trimming. By this adjustment, the number of strip-shaped thin-film resistors 26 interposed between the first strip-shaped thin-film conductor 24a and the second strip-shaped thin-film conductor 24b increases, and thus the resistance value decreases. Further, the degree to which the resistance value is reduced can be appropriately adjusted by changing the number of the strip-shaped thin-film resistors 26 connected to the first strip-shaped thin-film conductor 24 a.

Fig. 36 and 37 are plan views each showing a fifth configuration example of the resistance element.

The resistance element according to the present configuration example is configured by: (1) a first electrode 27; (2) a second electrode 28; (3) and a chip resistor 29a having one end connected to the first electrode 27 and the other end connected to the second electrode 28. The resistance value of the resistance element is adjusted by: (a) the chip resistor 29a is taken down; (b) another chip resistor 29b (one end connected to the first electrode 27 and the other end connected to the second electrode 28) having a different resistance value from that of the chip resistor 29a is mounted. Fig. 36 shows the resistance element before trimming, and fig. 37 shows the resistance element after trimming. When the resistance value of the new chip resistor 29b is larger than that of the original chip resistor 29a, the resistance value is increased by this adjustment. Conversely, when the resistance value of the new chip resistor 29b is smaller than the resistance value of the original chip resistor 29a, the resistance value is decreased by this adjustment.

Fig. 38 and 39 are plan views each showing a sixth configuration example of the resistance element.

The resistance element according to the present configuration example is configured by: (1) an electrode 31; (2) and a strip-shaped thin film resistor 32 having one end connected to the electrode 31. The electrode 31 is arranged in parallel with an electrode 33 to which an element is connected, and the strip-like thin-film resistor 32 is arranged in parallel with a strip-like thin-film conductor 34 having one end connected to the electrode 33. The resistance value of the resistance element is adjusted by: (a) short-circuiting the strip-shaped film resistor 32 and the strip-shaped film conductor 34 by welding or the like; (b) removing the element from the electrode 33; (c) the element is mounted on the electrode 31. Fig. 38 shows the resistance element before trimming, and fig. 39 shows the resistance element after trimming. By this adjustment, the strip-shaped thin-film resistor 32 is interposed between the strip-shaped thin-film conductor 34 and the element, and thus the resistance value increases. Further, by changing the portion that short-circuits the strip-shaped thin-film resistor 32 and the strip-shaped thin-film conductor 34, it is possible to appropriately adjust the degree to which the resistance value is increased.

Summary of the invention

A force sensor according to embodiment 1 of the present invention is a force sensor including a strain body having a deformation portion that deforms by an external force, and a strain gauge attached to the deformation portion, and has the following configuration. That is, the strain body has a protruding portion protruding from the deformation portion in a direction intersecting the longitudinal direction of the deformation portion.

According to the above structure, the protruding portion approaches the deformation portion, and even if the deformation portion is deformed, the protruding portion is difficult to be deformed. Therefore, according to the above configuration, the electrode, the resistance element, or the like connected to the strain gauge can be appropriately attached to the protruding portion.

In addition to the configuration of the force sensor according to embodiment 1, the force sensor according to embodiment 2 of the present invention has the following configuration. That is, the strain body has a core portion, a frame portion that surrounds the core portion and includes a flexure, and an arm portion that joins the core portion and the flexure, and the deformation portion is one or both of the arm portion and the flexure.

According to the above structure, the protruding portion approaches the arm portion or the flexible piece, and even if the arm portion or the flexible piece deforms, the protruding portion is hard to deform. Therefore, according to the above configuration, the electrode, the resistance element, or the like connected to the strain gauge can be appropriately attached to the protruding portion.

In addition to the configuration of the force sensor according to embodiment 1, the force sensor according to embodiment 3 of the present invention has the following configuration. That is, the strain body has a core portion, a frame portion surrounding the core portion, and an arm portion connecting the core portion and the frame portion, and the deformation portion is the arm portion.

According to the above structure, the protruding portion approaches the arm portion, and even if the arm portion deforms, the protruding portion is hard to deform. Therefore, according to the above configuration, the electrode, the resistance element, or the like connected to the strain gauge can be appropriately attached to the protruding portion.

The force sensor according to embodiment 4 of the present invention adopts the following configuration in addition to the configuration of the force sensor according to any one of embodiments 1 to 3. That is, an electrode or a resistance element connected to the strain gauge is attached to the protrusion.

According to the above configuration, when the electrode is attached to the protruding portion, the wiring operation can be easily performed. Further, according to the above configuration, in the case where the resistive element is mounted on the protruding portion, it is possible to suppress a decrease in accuracy of the force sensor due to a change in characteristics of the resistive element.

The force sensor according to embodiment 5 of the present invention adopts the following configuration in addition to the configuration of the force sensor according to any one of embodiments 1 to 4. That is, the protrusion has a neck portion and a head portion, wherein the head portion has a width wider than the neck portion, one end of the neck portion is connected to the deformation portion, and the other end of the neck portion is connected to the head portion.

According to the above configuration, it is possible to further suppress deformation of the protruding portion that may occur when the deformation portion is deformed.

The force sensor according to embodiment 6 of the present invention adopts the following configuration in addition to the configuration of the force sensor according to any one of embodiments 1 to 5. That is, the joining width of the protruding portion and the deformed portion is 1/2 or less of the length of the deformed portion.

According to the above configuration, it is possible to further suppress deformation of the protruding portion that may occur when the deformation portion is deformed.

The strain body according to embodiment 7 of the present invention is a strain body having a deformation portion that deforms by an external force, and has the following configuration, similar to the force sensor according to embodiment 1. That is, the strain body has a protruding portion protruding from the deformation portion in a direction intersecting the longitudinal direction of the deformation portion.

According to the above structure, the protruding portion approaches the deformation portion, and even if the deformation portion is deformed, the protruding portion is difficult to be deformed. Therefore, according to the above configuration, an electrode or an element (e.g., a resistance element) connected to an element (e.g., a strain gauge) attached to the deformation portion can be appropriately attached to the protrusion portion.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the respective technical means included in the above embodiments are also included in the technical scope of the present invention.

Description of the reference numerals

1 force sense sensor

11 strain body

111 part (force bearing part)

112 frame part (fixed part)

113a to 113c arm

114a to 114c through hole

115 a-115 c flexible member

12 strain gauge group

13 electrode group

14 resistor element group

15 bridge the circuit group.