Means of adjusting ground speed of a vehicle based on load on blade assembly

An assembly having a frame supported by a plurality of ground engaging wheels. Mounted to the frame is an operator control system that is connected to a controller that is powered by an electrical source. The controller is operatively connected to a blade assembly and a ground drive assembly and adjusts the ground speed of the assembly based upon the cutting load of the blade.

BACKGROUND OF THE INVENTION

This invention is directed to a vehicle assembly and more specifically to an assembly that adjusts ground speed based upon the load on a blade assembly.

Riding mowers are known in the art. Most riding mowers are driven mechanically by an internal combustion engine. These engines provide power to both a cutting blade assembly and a drive wheel assembly through adjustable ratio mechanical gearing systems such as variable ratio V-belts and the like. These mowers present certain drawbacks. Not only are these mowers expensive to manufacture, but they produce exhaust fumes and may leak hydraulic fluids that damage the turf.

Electrically powered mowers have addressed some of the these drawbacks. Still, due to power limitations, operators must exercise caution by reducing ground speed so as not to overload the cutting blade motor when heavy or tall grass is encountered that could stall the motor. Accordingly there exists a need in the art for an assembly and system that addresses these deficiencies.

An objective of the present invention is to provide an assembly that adjusts ground speed based upon the load on the blade.

Another objective is to provide an electrically powered assembly that is more efficient in its operation.

These and other objectives will be apparent to those skilled in the art based upon the following written description.

SUMMARY OF THE INVENTION

An assembly having a frame supported by a plurality of ground engaging wheels. Mounted to the frame is an operator control system that is connected to a controller that is powered by an electrical source. The controller is operatively connected to a blade assembly and a ground drive assembly and adjusts the ground speed of the assembly based upon the cutting load of the blade.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the Figures the self-propelled mower assembly10has a frame12supported by a plurality of ground engaging wheels14. For purposes of example only, the present invention is shown with regard to a riding mower. The invention may, however, be used for other applications, such as crop harvesting, hedge trimming, other vegetation maintenance, and the like. Mounted on the frame12is an operator control system16which includes conventional elements for operating a mower10such as a steering wheel and mechanism, control module, drive and brake pedals, mower activation and the like. Also mounted to the frame12is an electrical power source18. The electrical power source may be of any type such as a generator, battery, power cord or the like. Both the operator system16and the electrical power source18are connected to a controller20mounted on the frame. The controller20is powered by the electrical power source18and receives input signals from the operator control system16related to the operation of the mower10.

Electrically connected to the controller is a mounting blade assembly22. The blade assembly includes an electrical blade motor24that is operably connected to a rotatable blade26by a drive shaft28. Mounted to the assembly22is a sensor30that detects the rotational speed of the blade26. The blade is of any type such as a rotary blade, reel type blade, or the like.

A ground drive assembly32is also electrically connected to the controller20. The ground drive assembly32includes an electrical ground drive motor34that is operably connected to a ground drive mechanism such as wheel14by a ground drive shaft36.

In operation the mower is activated through the operator control system16. From signals sent from the operator control system16to the controller20the ground drive assembly32and the mowing blade assembly22are both activated to move the mower10in a forward and rearward direction and rotate the blade26respectively. The sensor30monitors the rotational speed of the blade26and/or drive shaft28and provides a signal to the controller that indicates the rotational speed.

When the blade26encounters a load (i.e. heavy grass) the rotational speed of the blade26will decrease and a signal indicating the decrease will be sent from the sensor30to the controller20. The controller20will compare the sensed speed with a pre-determined normal speed. Alternatively, the controller20may be configured to sense the cutting load on the blade26through measurement of torque or estimate the cutting load through measurements or estimates of electrical current that is drawn by the blade powering motor. When the controller20determines that the sensed speed is less than the predetermined normal speed or that the cutting load is higher than a predetermined value the controller20will send a signal to the ground drive motor34that will reduce the rotation of the ground drive shaft36and in turn the ground speed of the mower. As a result, the load on the blade26will be reduced, the cutting performance will be improved, and less stress and wear on the blade assembly22will be encountered.

In an alternative embodiment, as shown inFIG. 3, a hybrid system which combines mechanical and electrical drive concepts is used. Specifically, a mechanical power source38is connected to and provides power to the electrical power source18(i.e., generator, alternator, etc.). The mechanical power source38is also operably connected to a variable ratio ground drive transmission40which is operably connected to the ground drive mechanism14by ground drive shaft36.

In this embodiment, the operator control system16is connected to a transmission control system40. The transmission control system40is connected to controller20and sends to and receives signals from the controller. The transmission control system42is also connected to the variable ratio ground drive transmission. The blade assembly22is similarly connected to and controlled by the controller20as previously described. When the controller20determines that the speed of the blade is less than the pre-determined normal speed or that the cutting load is higher than a predetermined value a signal is sent to the transmission control system42which in turn adjusts the variable ratio ground drive transmission40such that the ground speed of the mower10is reduced.

In another hybrid embodiment, the mechanical power source38drives the blade26through a variable ratio blade transmission44. Specifically, the mechanical power source38is operably connected to the variable ratio blade transmission44by drive shaft46. The variable ratio blade transmission44is operably connected to the blade26by drive shaft28.

In addition to driving the blade26, the mechanical power source38supplies power to the electrical power source18which is electrically connected to controller20. The controller20is connected to the ground drive assembly as set forth in the first described embodiment.

The operator control system18is connected to the transmission control system42which is connected to both the variable ratio blade transmission44and the controller20. In this embodiment, a signal is received by the controller20through the transmission control system42that indicates either rotational speed or mechanical load of the blade. When the signaled speed is less than the pre-determined normal speed or when the cutting load is too high the controller20sends a signal to the ground drive assembly32that in turn reduces the ground speed of the mower.

Therefore, a self-propelled mower assembly that reduces the ground speed of a mower when the blade encounters a load has been disclosed that, at the very least, meets all the stated objectives.