Patent ID: 12208846

DETAILED DESCRIPTION

The present disclosure relates to a steering axle drive assembly for a vehicle and a method for completing a zero radius turn with a vehicle that has the drive assembly. Referring toFIG.1, there is shown a first embodiment of the assembly used with a zero radius turn mower2. The mower has a steering axle drive assembly4and rear axle assembly6, each of which include a pair of wheels8a,8band10a,10bconnected with each associated axle12,14. The front axle wheels8a,8ba are pivotally connected with each steering axle end for rotation about a vertical axis V and rotation about a horizontal axis H, respectively, independent of any controls related to the rear axle wheels10a,10b. A control mechanism16controls the position of each front steering axle wheel8a,8babout each respective vertical and horizontal axis. The control mechanism16includes a joystick18, a controller20and motors22a,22b. When the right joystick18is pivoted forward or back, a y-axis signal is sent to the controller20which engages the motors22a,22bto rotate the wheels8a,8bforward or reverse, respectively. When the joystick18is pivoted left or right, an x-axis signal is sent to the controller which engages the motors to rotate the wheels8a,8bleft or right, respectively. The controller can process both x and y signals simultaneously. Levers24a,24bconnected with the rear axle14are pushed forward or pulled back to control the rear wheels10a,10b, respectively. The front wheels8a,8bare thus steered and driven according to the inputs from the joystick18to the controller20independent of any control over the rear wheels10a,10b. It will be understood by those with skill in the art that, as detailed below, the control mechanism16could involve one or more joysticks, or other such devices, one or more controllers, one or more motors, or another method for rotating the steered axle wheels. Preferably, the steered axle wheels8a,8brotate about a vertical axis V over a range of at least 150-degrees and more desirably a range from 180- to 360-degrees.

Referring now toFIGS.2-5, embodiments of the steering axle assembly connected with tractors are shown.FIG.2shows a first tractor102with a steering axle drive assembly104attached thereto. The steering axle drive assembly104includes front wheels108a,108bthat are connected to ends of an angled steering axle112and controlled via linear actuators122a,122b, for instance pneumatic or hydraulic cylinders, which selectively prevent the wheels from rotating about pins126a,126bwhen a steering set point is reached, and by selectively allowing the wheels to rotate around the ends of the axle112when a steering angle change is initiated. The control mechanism116is connected with a controller120to drive the wheels forward and reverse via a joystick118a. Buttons118b,118cengage the right and left actuator, respectively, to steer the wheels. The steering axle drive assembly104of this embodiment also includes a pair of brakes128a,128bcontrolled via brake pedals130a,130bfor restricting horizontal rotation of each steering axle wheel108a,108b. The rear wheels110a,110bare controlled via a treadle132which is connected with a transmission134and differential136. The treadle drives the rear wheels110a,110bforward and reverse, and rear wheel brakes138a,138brestrict horizontal rotation of each rear wheel110a,110b, respectively. They are controlled via rear brake pedals140a,140b.

Referring toFIG.3, there is shown a tractor202that includes a steering axle drive assembly204with wheels208a,208band a rear axle assembly206with wheels210a,210b. The front wheels208a,208bare connected with the end of an angled steering axle212and are controlled via a control mechanism216, brakes228a,228b,228c,228and motors222a,222b. The control mechanism includes a first set of buttons218a,218bfor controlling drive brakes228a,228b, respectively, and a second set of buttons,218c,218dfor controlling steering brakes228c,228d, respectively. There is also a centrally located switch218efor shifting a front transmission242into forward or reverse and for driving the motors222a,222b. The front transmission is further connected with a front differential244for controlling the torque of the front wheels208a,208b. As with the tractor inFIG.2, there are rear wheels210a,210bcontrolled via a treadle232, a transmission234, a differential236and rear wheel brakes238a,238b, which are controlled by pedals240a,240b, respectively.

FIG.4shows a tractor302that includes a steering axle drive assembly304and rear axle assembly306, similar to those shown inFIGS.2and3. The steering axle drive assembly includes wheels308a,308bconnected with an angled steering axle312, and the rear axle assembly includes wheels310a,310bconnected with a rear axle314. The rear axle wheels are driven forward or reverse via a treadle332, a transmission334, and a differential336. Rear brakes338a,338bare controlled via pedals340a,340b. Similar toFIG.2, the steering axle drive assembly includes drive brakes328a,328bfor restricting horizontal rotation of the front wheels308a,308b, respectively, which are engaged by pedals330a,330b. The front wheels308a,308bare driven forward and reverse and steered left and right via a control mechanism316which includes a joystick318, a controller320, a transmission342, and motors222a,222bconnected with their respective wheels.

The embodiment shown inFIG.5is similar to those ofFIGS.2-4but the control mechanism416includes a steering wheel418aand a drive lever418bconnected with a transmission442and a differential444. The front wheels408a,408bare driven and steered independent of the rear wheels410a,410b, and are electrically controlled. As with the other tractor embodiments, there is a steering axle drive assembly404and a rear axle drive assembly406, each of which includes an axle412,414. There are also rear brakes438a,438band brake pedals440a,440b, respectively. The steering wheel418ais connected with the front wheels308a,308bto rotate them about their vertical axes, and the drive lever418bis connected with the transmission442to drive the wheels forward or reverse. A treadle432is connected with a rear axle transmission434and differential436to drive the rear wheels forward and reverse.

Referring now toFIGS.6and7, embodiments of a zero radius turn mower with a steering axle assembly are shown. InFIG.6, the mower502has a steering axle drive assembly504with wheels508a,508bthat are controlled independent of the vehicle rear wheels510a,510b. The vehicle includes a front512axle with front wheels508a,508band a control mechanism516for controlling rotation of the front wheels about their vertical V and horizontal H axes. The mower502also includes levers524a,524bconnected with the rear wheels510a,510bfor controlling the driving force of those wheels. There is an engine and dual hydrostatic pump drive or dual electric motor536for controlling the torque of the rear wheels. The control mechanism516of this embodiment includes buttons518a,518b,518c,518darranged on the levers524a,524band drive pedals530a,530b. The levers are pushed forward or pulled back to drive the tractor forward or reverse, respectively. The buttons are engaged to send a signal to a controller520which in turn causes motors522a,522bto steer the wheels508a,508b. The pedals530a,530bare pushed to engage additional motors522c,522dto drive the wheels.

FIG.7shows a zero radius turn mower602with a steering axle drive assembly604which is similar to the mower shown inFIG.6, but the control mechanism616for controlling the front wheels608a,608bincludes a single joystick618arranged on the right drive lever624b. The joystick618is moved forward/back and left/right to provide x and y signals, respectively, to a controller620, which in turn engages motors622a,622bto steer and drive the wheels according to the signals received by the controller. As with the mower ofFIG.6, the mower includes an engine and dual hydrostatic pump drive or dual electric motor636and rear wheels610a,610bwhich are controlled via drive levers624a,624b. The front pedals630a,630bapply brakes for controlling the horizontal rotation of the front wheels608a,608b.

Referring now toFIG.8, there is shown the method steps for controlling a vehicle to complete a zero radius turn. This allows the vehicle to drive directly to a location without the need for a multipoint turn involving both forward and reverse directions. The steps include independently rotating the wheels of the front axle about their respective vertical axes in a first direction to the left or right, and independently rotating at least one wheel of the rear axle about a horizontal axis forward or reverse.

More specifically, a method for controlling the tractor302ofFIG.4will now be described. To turn to the right, the steering axle wheels308a,308bof the first wheeled axle310are rotated about their vertical axes V to the right, a brake334ais applied to the rear left wheel310aof the second wheeled axle314, the front wheels are driven about their horizontal axes H in a forward direction, and the right wheel310bof the second wheeled axle is driven in reverse. To complete a turn to the left, the opposite is done. That is, the front wheels308a,308bare steered to the left, a brake334bis applied to the rear right wheel310b, the front wheels are driven forward, and the rear left wheel310ais driven in reverse. This allows for a zero radius turn without any scuffing or dragging of the front wheels.

Referring again toFIG.6, additional methods for maneuvering a vehicle having the steering axle drive assembly disclosed herein are described. The mower502includes four normally open momentary button switches518a,518b,518c,518d. When the left switches518a,518bare depressed, a steering motor522arotates the front left wheel508aabout the left pin526ato the left about its vertical axis V. The left pedal530ais engaged to send a signal to the controller520to power the hub motor522cto drive the left wheel508ain reverse. Alternatively, to steer the front left wheel508ato the right, only the left most button518ais depressed. The control of the left pedal and hub motor can be switched to drive the left wheel508aforward.

The right switches518c,518dand right pedal530bperform similar functions on the front right wheel508b. When both switches518c,518dare depressed, the steering motor522brotates the right wheel508babout the right pin526bto the left about its vertical axis V. To steer the front right wheel to the right, only one button518cis depressed. The right pedal530bis engaged to signal the controller520to power the hub motor522dto drive the right wheel508bin reverse. The control of the pedal and hub motor can be switched to drive the wheel forward.

It will be obvious to those skilled in the art that many different systems and switches might be used to control the steering motors and wheel speeds. Also, depending on terrain and size of the steering motor, the wheels may need to apply a braking force when the vehicle is moving rather than actually rotating the inside wheel backward. For instance, to turn left while the vehicle is going forward, a brake must be applied to the left front wheel, while the left steering motor turns the wheel to the left.

Referring again toFIG.6, to make a left turn, both left switches518a,518bon the left lever524aare pressed to signal the steering motor522ato steer the left wheel508ato the left, and both switches518c,518don right lever524bare pressed to signal the steering motor522bto steer the right wheel508bto the left. The right lever524bis then pushed further forward than the left lever524ato drive the right rear wheel510bfaster than the left rear wheel510a. To make a right turn, one button518aon the left lever524ais pressed, one button518don the right lever524bis pressed, and the left lever524ais moved further forward than the right lever524b. It will be understood by those with skill in the art that, rather than using buttons to complete these turns, a steering wheel with pedals or a lever (as shown inFIG.5) can be used. Further, as shown inFIG.7, a joystick and controller can be used to produce the signals that cause the motors to steer and drive the wheels.

In the embodiment ofFIG.6, there are pins526a,526bhaving sensors/indicators for aiding the operator of the vehicle with coordinating angles of the wheels508a,508b, preferably with demarcations so that individual turning radii can be chosen. This allows the operator to know when the two steering angles correspond to Ackerman steering, and whether the horizontal axes H of both wheels508a,508bpoint to a specific location on the rear axle514.

In this embodiment, a controller520receives steering command input from an operator through an operator interface546which receives signals from the buttons518a,518b,518c,518d. Sensors526a,526bsend signals to the controller520which can calculate Ackerman or other desired geometries when performing the steering command input received from the control mechanism516. As is shown in the other embodiments described above, a joystick or joysticks, steering wheel, pedals, levers or other devices can be substituted for the buttons518a,518b,518c,518d. Further, an algorithm, or indicator reference marks, can be substituted for the operator's judgement.

For this embodiment, the operator manually controls the speeds of the rear drive wheels510a,510b. It is easier to steer first and then coordinate the wheel speeds than it is to do both simultaneously. The pin with sensors526a,526bmeasure the steering angles and the controller520uses that information to dictate the actions of the steering motors in accordance with the steering command from the control mechanism516.

Referring again toFIGS.2-5, there is shown an angled steering axle112,212,312,412. The axle is angled such that a midsection148,248,348,448is arranged forward of axle ends150,250,350,450. When the wheels of these angled axles are rotated about their vertical axis to perform a turn, they can be steered to a position in which two radii extend from a center point of the rear axle114,214,314,414, through the horizontal axis of each front wheel to define a preferred geometric relationship between the angled axle wheels and the rear axle, such as with Ackerman steering. The tractor can then complete a zero-radius turn without sliding or scuffing. It will be understood by those of skill in the art that such an angled axle can be incorporated with the mowers ofFIGS.1,6and7, as well as with other similar vehicles.

Preferably, the above-noted angled axles are configured to form a 135-degree angle, but it will be understood by those with skill in the art that other angles that achieve the same geometric goals as described herein could be used.

Regardless of the vehicle with which the angled axle is used, the front steering wheels of that axle each have a horizontal and vertical axis about which each wheel rotates. Referring again toFIG.3, another method for steering and driving a tractor will be described. First, both the vertical axes brakes228c,228dare released, one of the horizontal axis brakes228a,228bof one wheel is engaged, and the horizontal axis brake of the other wheel is released. The front wheels208a,208bare then driven. The wheel without the horizontal axis brake engaged will be driven forward, while the wheel with the horizontal axis brake engaged will rotate about its vertical axis causing the mower to turn. The brakes and driving force of the two front wheels can be varied to steer the front wheels.

The vertical axis brake may be a traditional friction brake but might also be a hydraulic cylinder and rod. The steered wheels of the angled axle may rotate many degrees about their vertical axes, approaching 180 degrees or more. Hydraulic cylinders and rods cannot generate rotary motion of 180 degrees by themselves but can act as a brake over more than 180 degrees. When the brake is released, the wheel can move freely around the vertical axis to steer the machine, which is achieved by applying a driving force to the wheel. When the brake is applied, any driving force of the associated wheel drives the machine rather than steers it. It will be understood by those with skill in the art, that the wheels can be steered via a motor rather than with releasing one or more vertical axes brakes.

In addition to improved turning from the angled axle, an independent transmission on the front wheels further improves the effectiveness of a zero radius turn or any forward turn which is sufficiently sharp such that a rear wheel moves backwards. For instance, for a right turn where the tractor pivots about the right rear wheel, the axle allows the horizontal axes of the two front wheels to intersect at the right rear wheel. When the left rear wheel and the front wheels are driven forward, the right rear wheel is stationary, and a turn is achieved that is sharper and more effective than with other tractor axles known in the art.

In addition to mechanical or electric controls, the angled steering axle can be controlled by an electronic operator interface and/or a joystick. The x and y axes of the joystick provide directions to front wheels of a tractor that is retrofitted with the angled axle described above. The operator provides instructions to the front axle and the wheels mounted on it to drive forward and reverse and to steer with an Ackerman geometry as calculated by a controller. The operator is then tasked with the mechanical duties of operating the foot clutch, the manual transmission shift lever and rear wheel brakes.

Although the above description references particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised and employed without departing from the spirit and scope of the present disclosure.