FORCE SENSOR

• US 20160252410A1
• Filed: 11/04/2014
• Published: 09/01/2016
• Est. Priority Date: 11/05/2013
• Status: Active Grant

• Current Assignee: NSK Limited
• Original Assignee: NSK Limited
• Inventors: TESHIGAWARA, Seiichi, TOBITA, Kazuteru, KUWAHARA, Masaki
• Granted Patent: US 9,989,427 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01D 5/12 using electric or magnetic means G01D5/06 takes precedence
• CPC Class Codes: G01D 5/30 the beams of light being detected by photocells
• CPC Class Codes: G01L 1/005 by electrical means and not provided for in G01L1/06 - G01L1/22
• CPC Class Codes: G01L 1/2206 Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
• CPC Class Codes: G01L 5/166 using photoelectric means

Abstract

A force sensor includes: a base; a first movable portion arranged to face the base; a second movable portion arranged to face the first movable portion; a support that is provided on the base and rockably supports the first movable portion and the second movable portion; a joint that is provided to the support and rotatably supports the second movable portion; and a first detection unit that can detect a force component causing the first movable portion and the second movable portion to rock and a second detection unit that can detect a force component causing the second movable portion to rotate, when external force is applied to at least one of the first movable portion and the second movable portion.

Claims

1. A force sensor comprising:

a base;

a first movable portion arranged to face the base;

a second movable portion arranged to face the first movable portion;

a support that is provided on the base and rockably supports the first movable portion and the second movable portion;

a joint that is provided to the support and rotatably supports the second movable portion; and

a first detection unit that can detect a force component causing the first movable portion and the second movable portion to rock and a second detection unit that can detect a force component causing the second movable portion to rotate, when external force is applied to at least one of the first movable portion and the second movable portion.

2. The force sensor according to claim 1, wherein the first movable portion and the second movable portion are arranged above the base in a vertical direction.

3. The force sensor according to claim 1, wherein

the first detection unit includes three or more sensors, and

the sensors are capable of emitting light and detecting reflected light of the light.

4. The force sensor according to claim 1, wherein

the first detection unit includes four sensors, and

two of the four sensors are arranged on one straight line while remaining two sensors are arranged on another straight line orthogonal to the one straight line.

5. The force sensor according to claim 1, wherein

the support includes:

a first fixture supported by the base;

a plate spring portion that has a plate-like shape and is supported by the first fixture through a spacer to be able to undergo elastic deformation; and

a second fixture supported by the plate spring portion through a spacer,

the plate spring portion includes;

a base portion having a plate-like shape; and

a plurality of protrusions, where the protrusions are on the same plane as the base portion and protrude from the base portion, and surfaces of the protrusions come into contact with the spacer, and,

when external force is applied to the first movable portion, a part of each of the protrusions deforms depending on a displacement of the first movable portion, the part being closer to the base portion relative to a position in contact with the spacer.

6. The force sensor according to claim 5, wherein the support includes a plurality of the plate spring portions connected to face one another with spacing formed among the plate spring portions.

7. The force sensor according to claim 1, wherein the first detection unit includes three or more sensors that are provided on a top surface of the base and are capable of emitting light and obtaining a distance to a detection target by detecting reflected light of the light, and the first detection unit detects an angle of inclination of the first movable portion by using positions of the sensors and the distance to the detection target.

8. The force sensor according to claim 7, wherein the first detection unit includes three sensors that are arranged at equal intervals, each interval being 120°

, in a circumferential direction on a top surface of the base.

9. The force sensor according to claim 7, wherein the first detection unit includes four or more sensors, uses three of the sensors as a first set to detect an angle of inclination of the first movable portion on the basis of a position of each of the three sensors and the distance to the detection target, uses three of the sensors as a second set in which at least one sensor is different from the first set to detect an angle of inclination of the first movable portion, and obtains an angle of inclination of the first movable portion by averaging a plurality of detected results.

10. The force sensor according to claim 1, further comprising:

a first stopper restricting a rocking angle of the first movable portion and the second movable portion;

a second stopper restricting an amount of displacement of the first movable portion and the second movable portion in a direction in which the support is to be extended; and

a third stopper restricting an angle of rotation about a central axis of the second movable portion.

11. The force sensor according to claim 10, wherein the first stopper is a portion protruding from the base toward the first movable portion, is provided at three or more positions at equal intervals in a circumferential direction about a central axis of the support, and has a height from the base allowing a tip of the first stopper to come into contact with the first movable portion when a load exceeding a load with which the support can undergo elastic deformation is applied to the force sensor.

12. The force sensor according to claim 10, wherein the second stopper is a flanged portion that is provided at an upper end of a housing arranged to cover a periphery of the force sensor and protrudes toward a center, and has a height allowing a lower end face of the second stopper to come into contact with the second movable portion when a load exceeding a load with which the support can undergo elastic deformation is applied to the force sensor.

13. The force sensor according to claim 10, wherein the third stopper includes permanent magnets that are provided on, respectively, surfaces of the first movable portion and the second movable portion facing each other, the permanent magnet provided on the first movable portion protrudes from the surface of the first movable portion toward the second movable portion, and the permanent magnet provided on the second movable portion protrudes from the surface of the second movable portion toward the first movable portion and is provided at positions sandwiching the permanent magnet provided on the first movable portion in a circumferential direction.

14. The force sensor according to claim 1, wherein

the joint includes a shaft passing through the second movable portion, and

a first internal passage passing through the base, a second internal passage passing through the support, and a third internal passage passing through the shaft are arranged on the same straight line.