Measurement transmitter

Patent metadata

Field	Value
Publication number	US-9237684-B2
Application number	US-201214376942-A
Country	US
Kind code	B2
Filing date	Nov 22, 2012
Priority date	Dec 12, 2011
Publication date	Jan 12, 2016
Grant date	Jan 12, 2016

Abstract

A measurement transmitter for providing a measured value to a control system, comprising: a sensor having a transducer for outputting a primary signal dependent on the measured value; a first electronic circuit for processing the primary signal to an intermediate signal; a second electronic circuit for processing the intermediate signal to a signal representing the measured value, wherein the second electronic circuit has a signal output for outputting the signal to connection lines; a housing arrangement having a metal material, wherein the first electronic circuit has at least a first circuit carrier, and the second electronic circuit has at least a second circuit carrier, and wherein the first and second electronic circuits are positioned in the housing arrangement spaced from one another. Electrically conducting shielding and high frequency filters for protecting against HF disturbances, which can get into the housing arrangement via the connection lines. The electrically conducting shielding and the high frequency filters are arranged between the first and second circuit carriers.

First claim

The invention claimed is:

1. A measurement transmitter for providing a measured value of at least one measured variable to a control system, comprising:
a sensor having an electrical transducer for outputting a primary signal dependent on the current value of the measured variable;
a first electronic circuit for driving said transducer, for processing the primary signal and for outputting an intermediate signal dependent on the primary signal;
a second electronic circuit for feeding said first electronic circuit and for processing the intermediate signal for producing a signal representing the measured value of the measured variable, said second electronic circuit has a signal output for outputting the signal to connection lines;
a housing arrangement, which has at least one electrically conducting material, especially a metal material, said first electronic circuit has at least a first circuit carrier, and said second electronic circuit has at least a second circuit carrier, said first and second electronic circuits are positioned in said housing arrangement spaced from one another; and
an electrically conducting shielding and high frequency filters for protecting against HF disturbances, which can get into said housing arrangement via the connection lines, wherein:
said electrically conducting shielding and said high frequency filters are arranged between said first circuit carrier and said second circuit carrier;
said shielding includes an electrically insulating shield support having a metal shield layer;
said high frequency filter is separated by the shield layer from the second electronic circuit,
said shield support includes at least one via, by way of which said second electronic circuit is connected with said first electronic circuit;
at least one of the electrical vias is galvanically isolated from said metal shield layer and annularly surrounded by said metal shield layer;
the capacitance between said via and the shielding amounts to no more than 1 nf;
said at least one high frequency filter is arranged on said shield support;
said first electronic circuit is connected with said electrical via by way of said high frequency filter;
the separation of said high frequency filter from said via amounts to no more than 1 cm;
said shielding includes at least one electrically conducting annular sleeve shaped electrode, which surrounds said at least one electrical via, is galvanically isolated from said via and in galvanic contact with said shield layer;
said sleeve shaped electrode is embedded in said shield support; and
the radius of said sleeve shaped electrode is so selected that the capacitance between the annular electrode and the conductor of the via is compatible with the ignition protection type “intrinsically safe” (Ex i);
said metal shield layer is in galvanic contact with the electrically conducting material of said housing;
said housing arrangement and said shield layer form a Faraday cage around said first electronic circuit; and
said shield support is a separate, plate shaped component, which is installed in said housing arrangement.

2. The measurement transmitter as claimed in claim 1 , wherein:
said housing arrangement has an inner space, which in a plane, in which said shielding is arranged, has an inner cross sectional area, which is covered by said shielding by an amount not less than 75%, preferably not less than 80%, further preferably not less than 90% and especially preferably at least 98%.

3. The measurement transmitter as claimed in claim 1 , wherein:
said at least one high frequency filter includes at least one LC unit.

4. The measurement transmitter as claimed in claim 1 , wherein:
said housing arrangement includes a first housing module and a second housing module, which are connected with one another;
said first housing module contains said sensor, said first electronic circuit and said shielding;
said second housing module contains said second electronic circuit; and
said second housing module has an opening, via which said first electronic circuit is connected with the second electronic circuit.

5. The measurement transmitter as claimed in claim 4 , wherein:
an end section of said first housing module protrudes into the opening of said second housing module and is connected with a neck region of said second housing module surrounding the opening.

6. The measurement transmitter as claimed in claim 1 , wherein:
said sensor is one of: a pressure sensor, a fill level sensor, a temperature sensor, a flow sensor, a humidity sensor, a density sensor, a viscosity sensor, a conductivity sensor, a potentiometric sensor, an amperometric sensor, and an optical sensor.

Assignees

• Endress & Hauser Gmbh & Co Kg
• Endress & Hauser & Gmbh & Co Kg

Inventors

• Ruf Klaus
• Stib Ralph

Classifications

• H05K9/0007 Primary

  Casings (standardised racks H05K9/0062) · CPC title

• G01D11/245 Primary

  Housings for sensors · CPC title

• G01F15/14

  Casings, e.g. of special material · CPC title

• G01F23/00

  Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm · CPC title

• G01F15/00

  Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus · CPC title