Temperature compensated piezoelectric accelerometer

Claim 2

Acceleration measuring device comprising a casing, said casing including a seismic mass, pressure-exerting means and a piezo-electric element, and at least one temperature compensating element of substantial thickness located under pressure between the seismic mass and one surface of the piezo-electric element, said temperature compensating element having a coefficient of expansion greater than that of the surfaces of the adjacent piezo-electric element and of the pressure-exerting means to compensate for changes in temperature, each temperature compensating element being so chosen in thickness that in the case of a temperature change acting on the device, the piezoelectric signal so obtained is reduced to the minimum.

Claim 3

Acceleration measuring device comprising a casing, said casing including a seismic mass, pressure-exerting means and a piezo-electric element, and at least one temperature compensating element of substantial thickness located under pressure between the seismic mass and one surface of the piezo-electric element, said temperature compensating element having a coefficient of expansion greater than that of the surfaces of the adjacent piezo-electric element and of the pressure-exerting means to compensate for changes in temperature, each temperature-compensating element having a thickness at least approximately equal to the thickness of a piezo-electric element.

Claim 4

Acceleration measuring device comprising a casing, said casing including a seismic mass, pressure-exerting means and a piezo-electric element, and at least one temperature compensating element of substantial thickness located under pressure between the seismic mass and one surface of the piezo-electric element, said temperature compensating element having a coefficient of expansion greater than that of the surfaces of the adjacent piezo-electric element and of the pressure-exerting means to compensate for changes in temperature, each temperature-compensating element having a thickness at least approximately equal to the thickness of a piezo-electric element.

Claim 5

Acceleration measuring device according to claim 2, characterized in that the piezo-electric element consists of a quartz crystal system, and in that each temperature-compensating element has a thickness at least approximately equal to the thickness of a quartz crystal.

Claim 6

An acceleration measuring apparatus with temperature compensation, which includes a seismic mass acting under pre-stress on a piezo-electric system, wherein the improvement comprises at least one temperature compensating disc arranged at least at one end of the piezo-electric system between said system and the adjacent abutment therefor, said temperature compensating disc having a coefficient of expansion which is greater than that of the material of the adjacent abutment and that of the piezo-electric system and is at least as thick as the piezo-electric element of said system.

Claim 7

An acceleration measuring apparatus with temperature compensation, which includes a seismic mass acting under pre-stress on a piezo-electric system, wherein the improvement comprises at least one temperature compensating disc arranged at least at one end of the piezo-electric system between said system and the adjacent abutment therefor, said temperature compensating disc having a coefficient of expansion which is greater than that of the material of the adjacent abutment and that of the piezo-electric system and is at least as thick as the piezo-electric element of said system.

Claim 8

An apparatus according to claim 4, wherein said temperature compensating disc is arranged between the seismic mass and said piezo-electric system.

Claim 9

An apparatus according to claim 5, wherein a temperature compensating disc is arranged between the piezo-electric system and a base plate.

Claim 10

An apparatus according to claim 6, wherein said piezo-electric system consists of an uneven number of individual piezo-electric discs, at least one of the temperature compensating discs consisting of electrically conductive material and resting as output electrode on one end disc of the piezo-electric system, and an electric insulating disc arranged between the seismic mass and the adjacent temperature compensating disc.

Claim 11

An apparatus according to claim 4, wherein a temperature compensating disc is arranged between the piezo-electric system and a base plate.

Claim 12

An apparatus according to claim 4, wherein said piezo-electric system consists of an uneven number of individual piezo-electric discs, at least one of the temperature compensating discs consisting of electrically conductive material and resting as output electrode on one end disc of the piezo-electric system, and an electric insulating disc arranged between the seismic mass and the adjacent temperature compensating disc.

Claim 13

An acceleration force measuring device having a housing, comprising a seismic mass, a piezo-electric element and temperature compensating elements consisting of metallic discs whose thickness is such as to introduce an equal negative compensation charge to the positive charge caused by a temperature gradient entering the pre-stressed housing of the device.

Claim 14

An acceleration force measuring device having a housing, comprising a seismic mass, a piezo-electric element and temperature compensating elements consisting of metallic discs whose thickness is such as to introduce an equal negative compensation charge to the positive charge caused by a temperature gradient entering the pre-stressed housing of the device.

Claim 15

An acceleration measuring device with a seismic mass acting under pre-stress on a piezo-electric body consisting of at least one piezo-electric plate, characterized in that the piezo-electric body is provided on at least one side thereof with a temperature-compensating plate also under pre-stress which has a thickness that corresponds to at least half the thickness of the abutting piezo-electric plate and whose material has a coefficient of expansion greater than that of the piezo-electric body.

Claim 16

An acceleration measuring device with a seismic mass acting under pre-stress on a piezo-electric body consisting of at least one piezo-electric plate, characterized in that the piezo-electric body is provided on at least one side thereof with a temperature-compensating plate also under pre-stress which has a thickness that corresponds to at least half the thickness of the abutting piezo-electric plate and whose material has a coefficient of expansion greater than that of the piezo-electric body.

Claim 17

An acceleration measuring device with a seismic mass acting under pre-stress on a piezo-electric body consisting of at least one piezo-electric plate, charActerized in that the seismic mass is so dimensioned and assembled that upon assembly thereof into the device it can be adjusted by selective step-by-step material removal in order that the output signal has a calibrated and standardized sensitivity, whereby the use of the output signal is greatly facilitated.

Claim 18

An acceleration measuring device with a seismic mass acting under pre-stress on a piezo-electric body consisting of at least one piezo-electric plate, charActerized in that the seismic mass is so dimensioned and assembled that upon assembly thereof into the device it can be adjusted by selective step-by-step material removal in order that the output signal has a calibrated and standardized sensitivity, whereby the use of the output signal is greatly facilitated.

Claim 19

Acceleration measuring device comprising a piezo-electric assembly, said assembly comprising a sleeve-like inner casing, a seismic mass fixed within said casing, an end plate, a plurality of piezo elements in stacked pile form and temperature-compensating discs disposed between the seismic mass and the end plate, all said components being maintained under pre-stress within said inner casing, and the temperature compensating discs having a coefficient of expansion greater than that of the materials of the adjoining parts and being at least as thick as the piezo-element; and an outer casing structure surrounding said inner casing with a free space between the peripheral wall of the inner casing and the peripheral wall of the outer casing and at one end of the outer casing.

Claim 20

Acceleration measuring device comprising a piezo-electric assembly, said assembly comprising a sleeve-like inner casing, a seismic mass fixed within said casing, an end plate, a plurality of piezo elements in stacked pile form and temperature-compensating discs disposed between the seismic mass and the end plate, all said components being maintained under pre-stress within said inner casing, and the temperature compensating discs having a coefficient of expansion greater than that of the materials of the adjoining parts and being at least as thick as the piezo-element; and an outer casing structure surrounding said inner casing with a free space between the peripheral wall of the inner casing and the peripheral wall of the outer casing and at one end of the outer casing.