Motor vehicles – Steering by driving – Independently operable drive motors
Reexamination Certificate
2001-12-14
2004-10-26
Morris, Lesley D. (Department: 3611)
Motor vehicles
Steering by driving
Independently operable drive motors
Reexamination Certificate
active
06808032
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to zero turning radius vehicles, such as turf care vehicles, skid steer loaders, and the like, and more specifically, to riding lawn mowers that are driven-by-wire.
BACKGROUND OF THE INVENTION
Riding lawn mowers come in a variety of sizes and configurations. The typical riding lawn mower has an internal combustion engine that provides power to propel the riding lawn mower. In some riding lawn mowers, the internal combustion engine is used to turn a hydraulic pump(s) that supplies a flow of hydraulic fluid that is used to drive wheels on the mower. The hydraulically driven wheels propel the mower. The speed at which the mower is propelled can be controlled by adjusting the rate of flow of the hydraulic fluid to the wheels. The steering of the typical riding lawn mower is performed by a steering wheel that is mechanically linked to wheels on the mower. In the case of a hydraulically driven riding lawn mower, the steering can also be accomplished by adjusting the rate at which wheels on opposite sides of the mower rotate so that the wheels rotate at different rates. The rates at which the wheels rotate is controlled by adjusting the flow rate of the hydraulic fluid to the wheels. The adjusting of the flow rate can cause the wheels to rotate at different speeds and the mower to steer in the direction of the wheel that is rotating at the lower speed.
The typical hydraulically driven riding lawn mower uses a variety of mechanical linkages to control the speed of the mower and to steer the mower. The mechanical linkages are operated by a user of the mower. The user manipulates the mechanical linkages to cause the mower to be propelled and to control the direction in which the mower travels. For example, a steering wheel can be rotated to control the direction in which the wheels are oriented so that the direction in which the mower moves can be controlled. Levers can be mechanically linked to valves to control the operation of the valves. The levers are linked so that movement of the levers causes the valves to adjust the volume and direction of the flow of hydraulic fluid to each of the hydraulically driven wheels. The adjustment of the volume of flow of hydraulic fluid to each of the wheels controls the speed at which the wheels rotate. The levers can be manipulated so that a different volume of hydraulic fluid flows to each of the hydraulically driven wheels and each wheel rotates at a different speed relative to each other which controls the direction in which the mower travels. The adjustment of the direction of the flow of hydraulic fluid to each of the wheels controls the direction in which the wheels rotate and whether the riding lawn mower is propelled in a forward or backward direction.
While the use of mechanical linkages to control the operation of a typical riding lawn mower with hydraulically driven wheels has proved useful, the use of mechanical linkages has drawbacks. For example, adjustments to the control and operation of the lawn mower can be difficult and time consuming. The mechanical linkages may need to be adjusted in length or connected to different attachment points so the control and operation of the mower can be adjusted. Additionally, due to safety concerns about where a person adjusting the mechanical linkages needs to place their hands, some adjustments cannot be made while the mower is operating. Therefore, the results of the adjustments of the mechanical linkages cannot be ascertained until after the mower is in operation again. This can result in an iterative process of starting and stopping the mower and adjusting the mechanical linkages until the desired operation is achieved which may be a long and exhaustive process. Furthermore, it is not always feasible to use mechanical linkages to provide a complex or highly adjustable control scheme for the riding lawn mower. The operation of the mechanical linkages needs to be easy to understand and operate by a user of the mower. As a result, the mechanical linkages are limited to simple and easy movements that facilitate the control and operation of the mower and complex control schemes are difficult to make and may not be feasible to be used by a user of the mower.
Therefore, what is needed is a riding lawn mower that has a control scheme that allows for improved control of the mower while being easy to use and adjust. Such a control scheme should be intuitive to use and allow for adjustments of the controls during the operation of the mower. Furthermore, it would be advantageous if the control scheme were conducive to operation of the mower by a user with physical handicaps.
SUMMARY OF THE INVENTION
The present invention is directed to a riding lawn mower that has the above desired advantageous control scheme. The present invention is directed to an apparatus for providing a riding lawn mower that is driven-by-wire. In one preferred embodiment, the drive-by-wire riding lawn mower has at least two independently driven wheels that are capable of bi-directional rotation. The at least two wheels are independently driven so that operation of the at least two wheels causes the at least two wheels to independently rotate. The independent rotation of the at least two wheels propels and steers the mower. A microprocessor controls the operation of the at least two wheels in accordance with signals received by the microprocessor. The mower has at least one controller. The at least one controller sends signals to the microprocessor that the microprocessor uses to control the operation of the at least two wheels so that operation of the at least one controller causes the at least two wheels to propel and steer the mower.
Optionally, but preferably, the at least two wheels are hydraulically driven and the mower further comprises at least one hydraulic pump that provides a flow of hydraulic fluid to drive the at least two wheels. At least one proportional servo valve can be provided that controls a direction and speed of the flow of hydraulic fluid to the at least two wheels. The at least one valve is controlled by a microprocessor and adjusts the flow of hydraulic fluid to the at least two wheels in response to signals received from the microprocessor. The adjusting of the flow of hydraulic fluid by the at least one valve controls the direction and speed of rotation of the at least two wheels so that the mower can be propelled and steered. Even more preferably, the at least one hydraulic pump is one of a plurality of hydraulic pumps. A first hydraulic pump of the plurality hydraulic pumps provides a flow of hydraulic fluid to the first wheel of the at least two wheels. A second hydraulic pump of the plurality hydraulic pumps provides a flow of hydraulic fluid to a second wheel of the at least two wheels. The at least one proportional servo valve is one of a plurality of servo valves. A first valve of the plurality of valves adjusts the flow of hydraulic fluid from the first hydraulic pump to the first wheel in response to signals received from the microprocessor and a second valve of the plurality of valves adjusts the flow of hydraulic fluid from the second hydraulic pump to the second wheel in response to signals received from the microprocessor.
Optionally, the mower can further comprise a biasing switch. The biasing switch is selectively operable to adjust the operation of the at least two wheels so that the mower can track a desired path. The biasing switch sends signals to the microprocessor in response to operation of the biasing switch that the microprocessor uses to control the operation of the at least two wheels.
Optionally, the mower may further comprise a mode switch. The mode switch is selectively operable between a work position and a transport position to adjust the operation of the at least two wheels. The work position corresponds to normal operation of the mower. The transport position corresponds to high speed operation of the mower. The mode switch sends a signal to the microprocessor that the microprocessor uses to control the operation of the
Benson Terrance G.
Wuertz Robert M.
Harness & Dickey & Pierce P.L.C.
Morris Lesley D.
Royal, Jr. Paul
Textron Inc.
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