System and method for thermal protection of an electric winch

Abstract

Monitoring the temperature of the brush of the motor on an electric winch during operation and restricting the operation of the motor within a cooling range in order to minimize downtime and maximize runtime.

Claims

1. A method for protecting the motor of an electric winch from thermal damage, the method comprising: querying, using a programmable electronic control device, a motor temperature detected by a temperature sensor, the programmable electronic control device arranged in electrical circuit relationship with the temperature sensor and an electric winch motor; comparing using the programmable electronic control device, a motor temperature sensed by the temperature sensor to a time-temperature cooling curve for the electric winch motor; maintaining operation of the electric winch motor by way of the programmable electronic control device when the motor temperature is within a predetermined cooling range along the time-temperature cooling curve; immediately terminating the operation of the electric winch motor by way of the programmable electronic control device when the motor temperature reaches an upper limit of the predetermined cooling range; maintaining the termination of operation of the electric winch motor by way of the programmable electronic control device until the motor temperature reaches a lower limit of the predetermined cooling range; and immediately reinstating operation of the electric winch motor by way of the programmable electronic control device when the motor temperature reaches the lower limit of the predetermined cooling range.

2. The method of claim 1 wherein the motor temperature is a brush temperature.

3. The method of claim 2 further wherein the temperature sensor is a thermocouple.

4. The method of claim 1, wherein the upper limit of the predetermined cooling range is approximately 212° C.

5. The method of claim 1, wherein the lower limit of the predetermined cooling range is approximately 176° C.

6. A winch comprising: an electric winch motor including brushes; a temperature sensor arranged to indicate a motor temperature of the electric winch motor; a programmable control module in electrical circuit communication with the electric winch motor and the temperature sensor, the programmable control module including a time-temperature cooling curve for the electric winch motor and a predetermined cooling range for the electric winch motor along a slope of the time-temperature curve; the programmable control module arranged to immediately suspend operation of the electric winch motor when the motor temperature is equal to an upper limit of the predetermined cooling range, immediately resume operation of the electric winch motor when the motor temperature is equal to a lower limit of the predetermined cooling range, and maintain operation of the electric winch motor when the motor temperature is between the upper and lower limits of the predetermined cooling range.

7. A winch according to claim 6 wherein the temperature sensor is a thermocouple.

8. A winch according to claim 6 wherein the motor temperature is a brush temperature.

9. A winch according to claim 6 wherein the upper limit of the predetermined cooling range is about 212° C.

10. A winch according to claim 6 wherein the lower limit of the predetermined cooling range is about 176° C.

11. A method for increasing a duty cycle of an electric winch motor, the method comprising: maintaining operation of the electric winch motor within a predetermined cooling range by way of a programmable control module in electrical circuit relationship with the electric winch motor, the programmable control module immediately suspending operation of the electric winch motor when a motor temperature is equal to an upper limit of the predetermined cooling range and immediately resuming operation of the electric winch motor when the motor temperature is equal to a lower limit of the predetermined cooling range, the programmable control module programmed to maintain winch operation within the predetermined cooling range lying on a maximum slope of a temperature—time cooling curve for the electric winch motor.

12. The method of claim 11, wherein the motor temperature is a brush temperature.

13. The method of claim 12 further comprising monitoring the brush temperature using a thermocouple.

14. The method of claim 11 wherein the upper limit of the predetermined cooling range is about 212° C.

15. The method of claim 11 wherein the lower limit of the predetermined cooling range is about 176° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments of the invention will now be described in further detail. Other features, aspects, and advantages of the present invention will become better understood with regard to the following detailed description, appended claims, and accompanying drawings (which are not to scale) where:

(2) FIG. 1 is a schematic of an electric winch incorporating the preferred embodiment of the present invention;

(3) FIG. 2 is a flow chart of the operation of the present invention; and

(4) FIG. 3 is the temperature vs. time cooling chart for the electric motor of the winch.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

(5) Turning now to the drawings wherein like reference characters indicate like or similar parts throughout, FIGS. 1-3 illustrates the preferred embodiment of the present invention. The electric winch 20 is seen in FIG. 1. It has an electric motor 22, gear train 24, spool 26 and control module 28. Power from the motor 22 is transferred to the spool 26 via the gear train 24. The gear train 24 provides a mechanical advantage for the motor 22 in rotating the spool 26.

(6) The control module 28 controls operation of the electric motor 22. Line 30 is paid out and retrieved through rotation of the spool 26. Direction of rotation of the spool 26 is changed by changing the direction of rotation of the motor 22. The motor 22 is typically a direct current or DC motor. Thus by changing the polarity of the power the direction of rotation can be changed. The polarity of the power is controlled by the control module 28.

(7) The motor 22 has brushes 32 which transfer the electrical power to the field windings 34. The brushes 32 are the most heat intensive piece of the motor 22. In the preferred embodiment the temperature of at least one of the brushes 32 is monitored by a temperature sensor 36. While other temperature sensors 36 may be used, the preferred embodiment uses a thermocouple 38 to monitor this temperature. The thermocouple 38 is coupled or otherwise attached to the brush 32. The temperature reading of the brushes 32 is fed to the control module 20.

(8) As best seen in FIG. 2, the cooling range or fastest cooling temperature range for the electric motor 22 is from 212° C. down to 176° C. By using 212° C. as the upper limit of the operating limit and cooling range and then reinstating operation once the temperature of the electric motor 22 reaches 176° C. or the lower limit of the cooling range, the amount of shut down cooling time is minimized and the amount of operating time is maximized. The exact temperatures of the upper and lower limits of the cooling range may vary depending upon the materials used for the motor 22 and the design of the motor 22 and its housing.

(9) When the operation of the winch 20 is started it is at ambient temperature. This would most likely be anywhere from −30° C. to 45° C. The operation of the winch 20 continues uninterrupted until the temperature of the motor 22, as measured by the temperature sensor 36 in the brush 32, reaches 212° C. At that point, the control module 28 suspends operation of the motor 22, and in turn, the winch 20, until the temperature of the motor 22 reaches 176° C. At this point, the control module 28 reinstates operation of the motor 22, and in turn, the winch 20. Operation of the winch 20 continues uninterrupted until the temperature of the motor 22 reaches 212° C. At that point, the cooling cycle is initiated taking the motor 22 and winch 20 out of service until the lower temperature (176° C.) is reached.

(10) It should be noted, the gear train 24 could be planetary or traditional. Further, other types of temperature sensor 36 could be used with the present invention in lieu of the thermocouple.

(11) The foregoing description details certain preferred embodiments of the present invention and describes the best mode contemplated. It will be appreciated, however, that changes may be made in the details of construction and the configuration of components without departing from the spirit and scope of the disclosure. Therefore, the description provided herein is to be considered exemplary, rather than limiting, and the true scope of the invention is that defined by the following claims and the full range of equivalency to which each element thereof is entitled.