Method and apparatus for monitoring the effectiveness of corrosion inhibition of coolant fluid

• US 4,147,596 A
• Filed: 12/30/1977
• Issued: 04/03/1979
• Est. Priority Date: 12/30/1977
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Haynes, Gardner S., Baboian, Robert
• Primary Examiner(s): Weisstuch, Aaron
• Application Number:
  US05/866,074
• Time in Patent Office: 459 Days
• Field of Search: 204/1 C, 204/195 C, 324/29, 324/71 R, 324/65 CP, 73/86, 123/41.15, 340/59
• US Class Current: 205/775.5
• CPC Class Codes: F01P 2025/80 Concentration anti-freeze
• CPC Class Codes: F01P 2031/20 Warning devices
• CPC Class Codes: G01N 17/02 Electrochemical measuring systems for weathering, corrosion or corrosion-protection measurement

Abstract

A sensor is adapted to be mounted so that it comes in contact with coolant fluid of a vehicular cooling system. When the corrosion inhibiting characteristic of the fluid is effective to prevent corrosion a first potential range is produced whereas when the characteristic is ineffective a second range exists. The effectiveness of the inhibiting characteristic can be displayed in the form of a high impedance voltmeter mounted in the dashboard or other convenient location or indicating means such as a light can be actuated when the potential reaches a threshold level indicating that the inhibiting characteristic is not effective to prevent corrosion. The sensor comprises a reference electrode used with a single sensor electrode on one embodiment and with a pair of sensor electrodes in a second embodiment.

Claims

1. Apparatus for monitoring the corrosivity of fluid, comprising reservoir defining means, a reference electrode mounted in and electrically isolated from the reservoir means and extending into the reservoir, a pair of sensing electrodes extending into said reservoir and composed of dissimilar materials wherein one of the materials is either steel or aluminum, said pair of sensing electrodes being physically electrically short circuited together and mounted in and electrically isolated from the reservoir defining means and the reference electrode, and high impedance voltage responsive means coupled across the reference and sensing electrodes respectively.

2. Apparatus for monitoring the corrosivity of fluid according to claim 1 in which said voltage responsive means includes indicating means which is actuated when the voltage level between the reference and sensing electrodes reaches a threshold value.

3. Apparatus for monitoring the corrosivity of fluid according to claim 1 in which the reference electrode is formed of silver.

4. Apparatus according to claim 1 in which said pair of sensing electrodes comprises a single clad element having layers of steel and aluminum bonded together.

5. A sensor adapted to be inserted in an aperture in a wall defining a reservoir, comprising a tubular member, a reference electrode and a pair of sensing electrodes extending through the member, one of the sensing electrodes composed of steel and the other of the sensing electrodes composed of aluminum, the sensing electrodes being electrically short circuited to one another by direct physical connection, and electrically insulative material mounting the electrodes in spaced relation to the member with the pair of sensing electrodes spaced from the reference electrode.

6. Apparatus according to claim 5 in which said pair of sensing electrodes comprises a single clad element having layers of steel and aluminum bonded together.

7. A vehicular cooling system including means for monitoring the effectiveness of corrosion inhibitor in coolant fluid, comprising a radiator, an engine block in which cooling passages were formed, means connecting the radiator to the cooling passages in the engine block in a closed system, means to circulate coolant fluid through the cooling system, an aperture formed in a wall defining the cooling system, a sensor received in the aperture, a reference electrode and a pair of sensing electrodes mounted in the sensor, the pair of sensing electrodes being composed of dissimilar materials wherein one material is either steel or aluminum, said pair of sensing electrodes being physically electrically connected in short circuit relation to one another and spaced from the reference electrode, at least a portion of each sensing electrode being adapted to come in contact with coolant fluid contained in the cooling system, and high impedance voltage responsive means coupled across the reference and sensing electrodes respectively.

8. A process for indicating when the corrosion inhibitor in vehicular cooling fluids becomes ineffective to prevent corrosion of the cooling system housing, including the steps of selecting a pair of sensing electrodes composed of dissimilar materials wherein one material is either steel or aluminum, disposing a reference electrode and said pair of sensing electrodes in contact with the cooling fluid, physically electrically coupling said pair of sensing electrodes together in short circuit relation and coupling high impedance voltage responsive means across the reference and sensing electrodes respectively for providing an output corresponding to the difference in potential between the reference and sensing electrodes.

9. A process according to claim 8 in which said reference electrode is composed of a standard reference electrode material and said pair of sensing electrodes are composed of aluminum and steel.

10. A sensor adapted to be inserted in an aperture in a wall defining a reservoir, comprising a tubular member, a reference electrode and a pair of sensing electrodes composed of dissimilar materials extending through the member, one of the sensing electrodes being composed of either steel or aluminum, the sensing electrodes being electrically short circuited to one another by direct physical connection, and electrically insulative material mounting the electrodes in spaced relation to the member with a pair of sensing electrodes spaced from the reference electrode.