Vibration/acceleration sensor

• US 5,003,824 A
• Filed: 12/26/1989
• Issued: 04/02/1991
• Est. Priority Date: 12/26/1989
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Fukada, Tetsuji, Kainou, Kikuo, Wakamiya, Masayuki
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): MILLER, ROSE MARY
• Application Number:
  US07/456,372
• Time in Patent Office: 462 Days
• Field of Search: 73/651, 73/652, 73/654, 73/517 R, 73/DIG. 1, 73/DIG. 4, 310/329, 310/331
• US Class Current: 73/651
• CPC Class Codes: G01H 11/08 using piezoelectric devices
• CPC Class Codes: G01N 2291/02827 Elastic parameters, strength or force
• CPC Class Codes: G01P 15/0922 of the bending or flexing mode type
• CPC Class Codes: Y10S 73/04 Piezoelectric

Abstract

A vibration/acceleration sensor is provided which includes a basic sensor unit fixed to a casing adapted to be mounted on a body the vibrations of which are to be detected. The sensor unit is surrounded by a resinous material having a low heat transfer coefficient. The sensor unit includes a vibration detecting unit including a piezoelectric bending vibrator, thin plates each formed of, for example, a resinous material having a low heat transfer coefficient, provided respectively on the upper and lower surfaces of the vibration detecting unit, and a signal processing circuit formed on the upper thin plate.

Claims

1. A vibration/acceleration sensor comprising:

a basic sensor unit including a vibration detecting unit containing therein a piezoelectric bending vibrator having upper and lower surfaces, a first thin plate and a second thin plate provided respectively on the upper and lower surfaces of said vibration detecting unit,

a signal processing circuit provided on at least one of said first thin plate and said second thin plate,

a casing means for being mounted onto a body whose vibrations are to be detected, and a resinous material enclosing said basic sensor unit;

and wherein each of said first thin plate and said second thin plate is formed of a resinous material having a low heat transfer coefficient and include a printed circuit board formed of glass epoxy resin.

2. A vibration/acceleration sensor as claimed in claim 1, wherein said vibration detecting unit further comprises a piezoelectric element composed of two plate-like piezoelectric components bonded together to provide upper and lower surfaces, said two plate-like piezoelectric components having a polarizing axis in a thicknesswise direction thereof and having electrodes on said upper and lower surfaces thereof, a bending vibration mode vibrator comprising a member provided by forming a slit in said piezoelectric element, and fixing members having a high heat conductivity for fixing said bending vibration mode vibrator to clamp the same therebetween.

3. A vibration/acceleration sensor as claimed in claim 2, wherein said two plate-like piezoelectric components are bonded together with a metallic thin plate interposed therebetween, said metallic thin plate having a thermal expansion coefficient which is approximately equal to that of said piezoelectric element.

4. A vibration/acceleration sensor as claimed in claim 2, wherein said fixing members include displacing portions formed, respectively, with grooves having a depth which is equal to a displacement of said bending vibration mode vibrator at the time of a maximum permissible acceleration.