Bolt with function of measuring strain

• US 7,293,466 B2
• Filed: 07/19/2005
• Issued: 11/13/2007
• Est. Priority Date: 07/19/2005
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ohta, Hiroyuki, Sumigawa, Takashi
• Primary Examiner(s): Lefkowitz; Edward
• Assistant Examiner(s): ROY, PUNAM P
• Application Number:
  US11/183,803
• Publication Number:
  US 20070017295A1
• Time in Patent Office: 847 Days
• Field of Search: 737/61, 737/60, 737/63, 737/74, 737/77, 257/417
• US Class Current: 73/777
• CPC Class Codes: F16B 31/02 for indicating the attainment of a particular tensile load or limiting tensile load apparatus for, or method of, determining value of torque or twisting moment for tightening a nut or other member similarly stressed G01L5/24
• CPC Class Codes: G01B 7/18 using change in resistance
• CPC Class Codes: G01L 5/0004 Force transducers adapted for mounting in a bore of the force receiving structure G01L5/0009 takes precedence
• CPC Class Codes: G01L 5/24 for determining value of torque or twisting moment for tightening a nut or other member which is similarly stressed

Abstract

A bolt with a function of measuring strain, comprising a Wheatstone bridge circuit comprising a strain sensor and a dummy resistor, a translate circuit that amplifies a signal from the Wheatstone bridge circuit to convert the same into a digital signal, a transmitting circuit that transmits the digital signal outside the bolt, and a power circuit, by which electromagnetic wave energy received from outside the bolt is supplied as a power source for at least any one of the circuits.

Claims

1. A bolt having a Wheatstone bridge circuit comprising strain sensors and dummy resistors, wherein the strain sensor and the dummy resistor, which constitute the Wheatstone bridge circuit, are formed on a common silicon monocrystal substrate, the strain sensor includes a p-type impurity diffusion layer, the dummy resistor includes a p-type impurity diffusion layer, the strain sensor is formed to be lengthwise in a <

110>

direction of the silicon substrate, the dummy resistor is formed to be lengthwise in a <

100>

direction of the silicon substrate, and the strain sensor is disposed so that a lengthwise direction of the strain sensor extends in an axial direction of the bolt.

2. A bolt according to claim 1, comprising a translate circuit that amplifies a signal from the Wheatstone bridge circuit to convert the same into a digital signal, a transmitting circuit that transmits the digital signal outside the bolt, and a power circuit, by which electromagnetic wave energy received from outside the bolt is supplied as a power source for at least any one of the circuits.

3. A bolt according to claim 1, wherein a temperature sensor comprising an impurity diffusion layer is provided in the silicon substrate.

4. A bolt according to claim 1, wherein the silicon substrate has a (001) plane on surface thereof.

5. A bolt having a Wheatstone bridge circuit comprising a strain sensor and a dummy resistor, wherein the strain sensor and the dummy resistor, which constitute the Wheatstone bridge circuit, are formed in a common silicon monocrystal substrate, the strain sensor includes an n-type impurity diffusion layer, the dummy resistor includes an n-type impurity diffusion layer, the strain sensor is formed to be lengthwise in a <

100>

direction of the silicon substrate, the dummy resistor is formed to be lengthwise in a <

110>

direction of the silicon substrate, and the strain sensor is disposed so that a lengthwise direction of the strain sensor extends in an axial direction of the bolt.

6. A bolt having a Wheatstone bridge circuit comprising a strain sensor and a dummy resistor, wherein the strain sensor and the dummy resistor, which constitute the Wheatstone bridge circuit, are formed in a common silicon monocrystal substrate, the strain sensor includes a p-type impurity diffusion layer, the dummy resistor includes an n-type impurity diffusion layer, the strain sensor and the dummy resistor are formed to be lengthwise in a <

110>

direction of the silicon monocrystal substrate, and the strain sensor is disposed so that a lengthwise direction of the strain sensor extends in an axial direction of the bolt.

7. A bolt having a Wheatstone bridge circuit comprising a strain sensor and a dummy resistor, wherein the strain sensor and the dummy resistor, which constitute the Wheatstone bridge circuit, are formed in a common silicon monocrystal substrate, the strain sensor includes an n-type impurity diffusion layer, the dummy resistor includes a p-type impurity diffusion layer, the strain sensor and the dummy resistor are formed to be lengthwise in a <

100>

direction of the silicon monocrystal substrate, and the strain sensor is disposed so that a lengthwise direction of the strain sensor extends in an axial direction of the bolt.

8. A bolt according to claim 7, comprising a translate circuit that amplifies a signal from the Wheatstone bridge circuit to convert the same into a digital signal, a transmitting circuit that transmits the digital signal outside the bolt, and a power circuit, by which electromagnetic wave energy received from outside the bolt is supplied as a power source for at least any one of the circuits.

9. A bolt according to claim 7, wherein a temperature sensor comprising an impurity diffusion layer is provided in the silicon substrate.

10. A bolt according to claim 7, wherein the silicon substrate has a (001) plane on surface thereof.

11. A bolt having a Wheatstone bridge circuit comprising a strain sensor and a dummy resistor, wherein the strain sensor and the dummy resistor, which constitute the Wheatstone bridge circuit, are formed in a common silicon monocrystal substrate, and include a p-type impurity diffusion layer, and are formed to be lengthwise in a <

110>

direction of the silicon monocrystal substrate, the strain sensor is disposed so that a lengthwise direction of the strain sensor extends in an axial direction of the bolt, and the dummy resistor is disposed so that a lengthwise direction of the dummy resistor extends perpendicular to the axial direction of the bolt.

12. A bolt according to claim 11, comprising a translate circuit that amplifies a signal from the Wheatstone bridge circuit to convert the same into a digital signal, a transmitting circuit that transmits the digital signal outside the bolt, and a power circuit, by which electromagnetic wave energy received from outside the bolt is supplied as a power source for at least any one of the circuits.

13. A bolt according to claim 11, wherein a temperature sensor comprising an impurity diffusion layer is provided in the silicon substrate.

14. A bolt according to claim 11, wherein the silicon substrate has a (001) plane on surface thereof.

15. A bolt having a Wheatstone bridge circuit comprising a strain sensor and a dummy resistor, wherein the strain sensor and the dummy resistor, which constitute the Wheatstone bridge circuit, are formed in a common silicon monocrystal substrate, and include an n-type impurity diffusion layer, and are formed to be lengthwise in a <

100>

direction of the silicon substrate, the strain sensor is disposed so that a lengthwise direction of the strain sensor extends in an axial direction of the bolt, and the dummy resistor is disposed so that a lengthwise direction of the dummy resistor extends perpendicular to the axial direction of the bolt.