US 7,603,786 B2
	Piezoelectric quartz level sensor
Fuxue Zhang, Beijing (China); and Wei Zhang, Beijing (China)
Assigned to Beijing Information Technology Institute, Beijing (China)
Filed on Sep. 29, 2007, as Appl. No. 11/906,201.
Claims priority of application No. 2007 1 0118525 (CN), filed on Jul. 09, 2007.
Prior Publication US 2009/0013543 A1, Jan. 15, 2009
Int. Cl. G01C 9/06 (2006.01)

U.S. Cl. 33—366.11  [33/365]

16 Claims

1. A piezoelectric quartz level sensor, comprising a sensitive element, a signal processing circuit, a bottom base frame, an outer case and a socket, wherein said sensitive element comprises two round piezoelectric quartz wafers symmetrically mounted on the two sides of the axial line of a column between a top plate and a bottom plate, an overload protective unit on the axial, transverse, and vertical directions of the piezoelectric quartz wafers, wherein said axial overload protect unit comprises a sensitive block, a shock pad between said bottom plate and a pallet, and an adjustable axial retaining bolt on a mass column of the sensitive block, and said transverse and vertical overload protective unit comprises an overload protective frame, and four adjustable retaining bolts provided on said overload protective frame around said mass column, wherein said sensitive element further comprises a sealed cavity cover and a base that is fastened to said sealed cover.