INDUCTIVE CONDUCTIVITY SENSOR AND METHOD

• US 20160356736A1
• Filed: 06/01/2016
• Published: 12/08/2016
• Est. Priority Date: 06/01/2015
• Status: Active Grant

• Current Assignee: Endress+Hauser Conducta GmbH+Company KG (Endress+Hauser AG)
• Original Assignee: Endress+Hauser Conducta GmbH+Company KG (Endress+Hauser AG)
• Inventors: Nagel, Thomas, Pfeifer, Andr, Fanselow, Christian
• Granted Patent: US 10,261,035 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01N 27/025 a current being generated within the material by induction
• CPC Class Codes: G01N 27/08 which is flowing continuously

Abstract

The disclosure includes an inductive conductivity sensor for measuring the specific electrical conductivity of a medium with a transmitter coil energized by an input signal, a receiver coil coupled with the transmitter coil via the medium, which receiver coil supplies an output signal that is a measure for the conductivity of the medium, and a housing enclosing the transmitter coil and the receiver coil, which housing comprises at least one housing section designed to be immersed in the medium, the housing wall of said housing section surrounding the transmitter coil and the receiver coil. The housing is made of a magnetic plastic or resin for inductively decoupling the transmitter coil from the receiver coil. In certain embodiments, the housing may be made of a ferromagnetic material. Another aspect of the disclosure includes a method for manufacturing the conductivity sensor.

Claims

1. An inductive conductivity sensor for measuring the specific electrical conductivity of a medium, the sensor comprising:

a transmitter coil energized by an input signal;

a receiver coil, the receiver coil coupled with the transmitter coil via the medium, wherein in response to the input signal the receiver coil generates an output signal that is a measure for the conductivity of the medium; and

a housing, the housing enclosing the transmitter coil and the receiver coil and the housing including a first portion comprising a magnetic plastic or resin material, wherein at least the first portion of the housing is sealed from intrusion by the medium, and

wherein the transmitter coil and the receiver coil are arranged within the housing such that the transmitter coil and the receiver coil are inductively decoupled by the first portion of the housing.

2. The sensor of claim 1, wherein the magnetic plastic or resin material is a ferromagnetic plastic or resin material.

3. The sensor of claim 1, wherein the housing includes a second portion comprising a plastic or resin material that is different from the plastic or the resin of the first portion.

4. The sensor of claim 3, wherein the second housing portion is insert-molded at least partially around the first portion.

5. The sensor of claim 1, further comprising a circuit board with conductor paths and a ground plane, the circuit board disposed between the transmitter coil and the receiver coil such that the ground plane capacitively decouples the transmitter coil and the receiver coil, wherein the transmitter coil and the receiver coil are in electrical contact with the circuit board.

6. The sensor of claim 3, further comprising a circuit board with conductor paths and a ground plane, the circuit board disposed between the transmitter coil and the receiver coil such that the ground plane capacitively decouples the transmitter coil and the receiver coil, wherein the transmitter coil and the receiver coil are in electrical contact with the circuit board.

7. The sensor of claim 5, further comprising a temperature sensor.

8. The sensor of claim 7, wherein the temperature sensor is disposed outside the housing.

9. The sensor of claim 8, wherein the circuit board extends from the housing and the temperature sensor is connected to the circuit board.

10. The sensor of claim 1, further comprising at least one cover made of a magnetic plastic or resin material, wherein the at least one cover caps the housing adjacent transmitter coil and/or the receiver coil.

11. The sensor of claim 10, wherein the magnetic plastic or resin material is a ferromagnetic plastic or resin material.

12. The sensor of claim 1, wherein the sensor includes pressure and/or flow rate sensors, and the housing includes recesses for the pressure and/or flow rate sensors.

13. A method for manufacturing an inductive conductivity sensor, comprising the steps of:

manufacturing a first portion of a housing from a magnetic plastic or resin material;

inserting a transmitter coil and a receiver coil in the first portion of the housing;

insert-molding a second portion of the housing from a plastic or a resin material that is different from the magnetic plastic or resin of the first portion, wherein the second portion of the housing at least partially surrounds the first portion.

14. The method of claim 13, wherein the magnetic plastic or resin of the first portion of the housing is a ferromagnetic plastic or resin material.

15. The method of claim 13, further comprising:

arranging the transmitter coil and the receiver coil on a circuit board such that the transmitter coil and the receiver coil are in electrical contact with the circuit board; and

insert-molding the circuit board with a plastic or resin material that is different from the magnetic plastic or resin of the first housing portion.

16. The method of claim 15, wherein the circuit board includes a temperature sensor.

17. The method of claim 16, wherein the temperature sensor is disposed outside the housing.