# US 9,039,275 B2 · Methods of preventing freezing of relays in electrical components

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- Number: US 9,039,275 B2
- Document ID: US9039275B2
- Status: Granted
- Kind: B2
- Application number: 13/350,009
- Filed: 2012-01-13
- Published: 2013-07-18
- Granted: 2015-05-26
- Earliest claimed: 2012-01-13
- Assignees: Nissan North America, Inc.
- Applicants: Greg Szleszynski; Adrian Dobre; Teofil Barjuca; Ryutaro Mine; Jim Beach; Adam Wehner; Tim Balogh
- Inventors: Greg Szleszynski; Adrian Dobre; Teofil Barjuca; Ryutaro Mine; Jim Beach; Adam Wehner; Tim Balogh
- Web page: https://patentgrep.com/patent/US9039275B2

## CPC

- H01H 47/002: {Monitoring or fail-safe circuits}
- G01R 31/006: {on road vehicles, e.g. automobiles or trucks (testing of ignition installations peculiar to internal combustion engines F02P17/00)}
- G01R 31/3278: {of relays, solenoids or reed switches (measuring contact resistance G01R27/205; high voltage magnetic switches G01R31/3271, G01R31/333; testing electric windings G01R31/72; monitoring of fail safe circuits H01H47/002)}
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

Disclosed herein are methods of preventing freezing of relays in electrical components operated in specific atmospheric conditions. One such method described herein comprises monitoring a temperature of a relay with a thermocouple located on a contact of the relay while monitoring ambient temperature within the relay. Operation of the electrical component is simulated in a sub-zero temperature and high humidity condition. A freeze potential of the relay is determined by plotting a temperature cross-over curve, wherein both the ambient temperature and the contact temperature are plotted during the operation and cool down period. If the high freeze potential is determined, one or both of the relay and the electrical component are modified with a modification configured to decrease the high freeze potential.

## Claims

### Claim 1

A method of preventing freezing of relays in an electrical component comprising:
operating the electrical component in a sub-zero temperature and high humidity condition;
cooling down of the electrical component un-powered in the sub-zero temperature and high humidity condition; and
determining a freeze potential of the relay from a temperature cross-over curve.

### Claim 2 (depends on 1)

The method of claim 1, wherein determining the freeze potential of the relay comprises:
monitoring a temperature of a contact within the relay with a first thermocouple located on the contact;
concurrently monitoring ambient temperature within the relay with a second thermocouple during the operating and the cooling down; and
plotting the temperature cross-over curve, wherein both the ambient temperature and the temperature of the contact are plotted during the operating and the cooling down, wherein if the temperature of the contact and the ambient temperature cross on the temperature cross-over curve, a high freeze potential of the relay is determined and if the temperature of the contact and the ambient temperature do not cross on the temperature cross-over curve, a low freeze potential of the relay is determined.

### Claim 3 (depends on 2)

The method of claim 2, wherein the electrical component is a power distribution module of a vehicle and the simulating operation of the relay comprises idling the vehicle for a first period of time, leaving the vehicle un-powered for a second period of time, and restarting the vehicle.

### Claim 4 (depends on 3)

The method of claim 3, wherein the second period of time is greater than the first period of time.

### Claim 5 (depends on 3)

The method of claim 3, wherein if the high freeze potential is determined, the method further comprises:
modifying one or both of the relay and the electrical component with a modification configured to decrease the high freeze potential.

### Claim 6 (depends on 5)

The method of claim 5, wherein the modification is selected from the group consisting of: removing existing heat dissipaters from the power distribution module, adding ventilation to the power distribution module, moving the relay to a different location within the power distribution module, moving the power distribution module to a different location within an engine compartment of the vehicle and combinations thereof.

### Claim 7 (depends on 1)

The method of claim 1, wherein the low temperature and high humidity condition is at or below −20° C. and at or above 90% relative humidity.

### Claim 8 (depends on 1)

The method of claim 1 further comprising pre-conditioning the relay prior to the operating.

### Claim 9 (depends on 8)

The method of claim 8, wherein pre-conditioning comprises:
drying the relay for a third period of time;
soaking the relay in a high temperature and high humidity condition for a fourth period of time;
cooling the relay to a sub-zero temperature; and
holding the relay at the sub-zero temperature for a fifth period of time.

### Claim 10 (depends on 9)

The method of claim 9, wherein drying comprises:
operating the electrical component in a high heat and low humidity condition; and
holding the electrical component in the high heat and low humidity condition in a power-off state.

### Claim 11 (depends on 9)

The method of claim 9, wherein the high temperature and high humidity condition comprises a temperature of about 80° C. or higher and a humidity of about 90% relative humidity or higher.

### Claim 12 (depends on 9)

The method of claim 9, wherein the fourth period of time is about 90 hours or greater.

### Claim 13 (depends on 9)

The method of claim 9, wherein the sub-zero temperature is about −20° C. or below.

### Claim 14 (depends on 9)

The method of claim 9, wherein the fifth period of time is about 20 hours or greater.

### Claim 15 (depends on 1)

The method of claim 1, wherein the operating of the electrical component comprises:
placing the electrical component in a chamber with temperature control configured to control a temperature of an internal atmosphere of the chamber;
reducing the temperature of the internal atmosphere of the chamber to a sub-zero temperature;
humidifying the internal atmosphere of the chamber with saturated air supplied from a humidifier in fluid communication with the internal atmosphere; and
providing power to the electrical component for a first period of time.

### Claim 16 (depends on 1)

The method of claim 1 further comprising:
placing the electrical component in a chamber with temperature control configured to control a temperature of an internal atmosphere of the chamber;
reducing the temperature of the internal atmosphere of the chamber to a sub-zero temperature; and
humidifying the internal atmosphere of the chamber with saturated air supplied from a humidifier in fluid communication with the internal atmosphere.

### Claim 17 (depends on 16)

The method of claim 16, wherein the operating comprises providing power to the electrical component for a first period of time while the electrical component is sealed in the chamber and the cooling down comprises leaving the electrical component un-powered for a second period of time.

### Claim 18 (depends on 17)

The method of claim 17, wherein determining the freeze potential of the relay comprises:
providing power to the electrical component for a second time, wherein a low freeze potential is determined if contacts of the relay close when power is provided for the second period of time and a high freeze potential is determined if the contacts of the relay do not close when power is provided for the second period of time.

### Claim 19 (depends on 18)

The method of claim 18, wherein the electrical component is a power distribution module of a vehicle and the contacts of the relay closing is indicated by the vehicle starting, and failure of the contacts to close is indicated by the vehicle failing to start.

### Claim 20

A method of preventing freezing of relays in an electrical component comprising:
monitoring a temperature of a contact within a relay with a first thermocouple located on the contact;
concurrently monitoring ambient temperature within the relay with a second thermocouple;
operating the electrical component in a sub-zero temperature and high humidity condition during temperature monitoring;
cooling down of the electrical component un-powered in the sub-zero temperature and high humidity condition during temperature monitoring; and
determining a freeze potential of the relay by plotting a temperature cross-over curve, wherein both the ambient temperature and the temperature of the contact are plotted during the operating and the cooling down, wherein if the temperature of the contact and the ambient temperature cross on the temperature cross-over curve, a high freeze potential of the relay is determined and if the temperature of the contact and the ambient temperature do not cross on the temperature cross-over curve, a low freeze potential of the relay is determined.