TECHNICAL FIELD

This disclosure relates generally to winches on movable machines and, more particularly, to a system and method for controlling the operation of a hydraulic winch.

BACKGROUND

Machines such as dozers often include a winch. The winch may be used to perform a variety of tasks and operate in different modes. These modes permit the winch cable to be reeled in or reeled out in a controlled manner to permit an operator perform a desired task. Mechanical winch assemblies are often difficult or challenging to control. Hydraulic winch assemblies may require a substantial amount of cooling capability in order to prevent overheating.

In some operations, when operating a machine such as an excavator along a steep slope, one or more dozers may be interconnected by winch cables to the machine on the slope. It is typically desirable for the dozer closest to the machine operating on the steep slope to have an experienced operator due to the complexity of the winch operation and risks associated with supporting the machine on the steep slope. However, experienced winch operators may not be available.

U.S. Pat. No. 3,249,336 discloses a machine having a hydraulically driven winch assembly. A hydraulic motor drives a drive shaft operatively connected to a shaft of the winch drum on which the winch cable is disposed. The drive shaft of the hydraulic motor is operatively connected to the shaft of the winch drum through a pair of bevel gears.

The foregoing background discussion is intended solely to aid the reader. It is not intended to limit the innovations described herein, nor to limit or expand the prior art discussed. Thus, the foregoing discussion should not be taken to indicate that any particular element of a prior system is unsuitable for use with the innovations described herein, nor is it intended to indicate that any element is essential in implementing the innovations described herein. The implementations and application of the innovations described herein are defined by the appended claims.

SUMMARY

In a first aspect, a system for controlling an operation of a winch assembly includes a rotatable winch drum, a winch cable, a hydraulic winch motor, a cable tension sensor, and a controller. The winch cable is wrapped around the rotatable winch drum, the winch motor is operatively connected to the rotatable winch drum and includes a first port and second port for receiving hydraulic fluid, and the cable tension sensor is operatively connected to the winch cable and configured to generate tension data indicative of a tension on the winch cable. The controller is configured to access a winch load threshold, with the winch load threshold defining a hold zone and a reel zone of the winch assembly, and one of the hold zone and the reel zone including loads on the winch cable greater than the winch load threshold and another of the hold zone and the reel zone including loads on the winch cable less than the winch load threshold. The controller is further configured to determine whether the winch assembly is operating within the hold zone or the reel zone based upon the tension data from the cable tension sensor, generate a zero flow command to prevent flow of hydraulic fluid to the hydraulic winch motor while the winch assembly is operating within the hold zone and preventing rotation of the hydraulic winch motor, and generate a pressure differential command to permit a desired flow of hydraulic fluid to the hydraulic winch motor at a desired pressure differential while the rotatable winch drum is operating within the reel zone, with the desired flow of hydraulic fluid being based upon the winch load threshold and operating to permit rotation of the hydraulic winch motor.

In another aspect, a method of controlling an operation of a winch includes accessing a winch load threshold with the winch load threshold defining a hold zone and a reel zone of the winch assembly, and one of the hold zone and the reel zone including loads on a winch cable wrapped around a rotatable winch drum being greater than the winch load threshold and another of the hold zone and the reel zone including loads less than the winch load threshold. The method further includes determining whether the winch assembly is operating within the hold zone or the reel zone based upon the tension data from the cable tension sensor, with the cable tension sensor being operatively associated with the winch cable and the tension data being indicative of a tension on the winch cable, generating a zero flow command to prevent flow of hydraulic fluid to the hydraulic winch motor while the winch assembly is operating within the hold zone and preventing rotation of the hydraulic winch motor, and generating a pressure differential command to permit a desired flow of hydraulic fluid to the hydraulic winch motor at a desired pressure differential while the rotatable winch drum is operating within the reel zone, with the desired flow of hydraulic fluid being based upon the winch load threshold and operating to permit rotation of the hydraulic winch motor.

In still another aspect, a machine includes a prime mover, a ground-engaging drive mechanism, a winch assembly, and a controller. The ground-engaging drive mechanism is operatively coupled to the prime mover to propel the machine. The winch assembly includes a rotatable winch drum, a winch cable, a hydraulic winch motor, a cable tension sensor, and a controller. The winch cable is wrapped around the rotatable winch drum, the winch motor is operatively connected to the rotatable winch drum and includes a first port and second port for receiving hydraulic fluid, and the cable tension sensor is operatively associated with the winch cable and configured to generate tension data indicative of a tension on the winch cable. The controller is configured to access a winch load threshold, with the winch load threshold defining a hold zone and a reel zone of the winch assembly, and one of the hold zone and the reel zone including loads on the winch cable greater than the winch load threshold and another of the hold zone and the reel zone including loads on the winch cable less than the winch load threshold. The controller is further configured to determine whether the winch assembly is operating within the hold zone or the reel zone based upon the tension data from the cable tension sensor, generate a zero flow command to prevent flow of hydraulic fluid to the hydraulic winch motor while the winch assembly is operating within the hold zone and preventing rotation of the hydraulic winch motor, and generate a pressure differential command to permit a desired flow of hydraulic fluid to the hydraulic winch motor at a desired pressure differential while the rotatable winch drum is operating within the reel zone, with the desired flow of hydraulic fluid being based upon the winch load threshold and operating to permit rotation of the hydraulic winch motor.

