AUTOMATIC DRIVE SYSTEM FOR A VEHICLE AND VEHICLE HAVING SUCH AN

AUTOMATIC DRIVE SYSTEM

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority benefit of U.S. Provisional Patent

Application Serial No. 61/001,832 filed November 5, 2007.

BACKGROUND OF THE INVENTION Field of Invention

[0002] The invention relates to vehicles having belt drive systems and, more particularly, to vehicles, such as riding lawn mowers, which utilize a transaxle having a single control lever for controlling direction and speed of the vehicle.

Description of Related Art

[0003] It is known to use a transaxle and a belt drive system on vehicles such as riding mowers to drive the vehicle in both the forward and reverse directions. In some applications, it is known to have the vehicle's engine drive a first belt which acts either directly or indirectly on a variator which in turn causes a second belt to drive the input sheave to the transaxle. By varying the tension on the first belt, the variator increases or decreases the speed of rotation of the second belt. The benefit of using a vehicle belt drive, as described, is that the performance characteristic of a hydrostatic drive may be simulated without incurring the requisite expense associated with conventional hydrostatic transmissions.

[0004] However, these applications typically use separate controls to shift the transaxle from a forward to a reverse operating mode. Therefore, a separate control is necessary for directional change from that used to vary the speed of the belt drive. If vehicle direction and speed could be controlled by a single control lever, much like that employed in conjunction with vehicles having hydrostatic transmissions, it would enhance operator convenience and simplify the operation thereof. Thus, there is a

need for a single lever control for a vehicle belt drive which provides for both direction and speed control.

SUMMARY OF THE INVENTION

[0005] The invention is directed to an improved a belt drive system for a vehicle such as a riding lawn mower. The belt drive system includes a prime mover and an output double-stacked pulley rotated by the prime mover. The belt drive system also includes a transaxle having an input shaft and an input double-stacked pulley connected to the input shaft. A forward belt drive system operatively connects a first sheave of the output pulley to a first sheave of the input pulley, and a reverse belt drive system operatively connects a second sheave of the output pulley to a second sheave of the input pulley. The forward belt drive system rotates the input shaft of the transaxle in a first direction to drive the vehicle in a forward direction, and the reverse belt drive system rotates the input shaft in the opposite direction to drive the vehicle in a reverse direction.

[0006] Another aspect of the invention is directed to a vehicle such as a lawn or garden tractor. The vehicle includes a prime mover, a transaxle having an input shaft, and a pair of ground-engaging drive wheels connected to the transaxle. A belt drive system connects the prime mover to the transaxle in order to rotate the drive wheels so as to provide locomotion to the vehicle. The belt drive system includes a double-stacked output pulley rotated by the prime mover and a double-stacked input pulley attached to the input shaft of the transaxle. A forward belt drive system connects a first sheave of the output pulley to a first sheave of the input pulley and a reverse belt drive system connects a second sheave of the output pulley to a second sheave of the input pulley. The reverse belt drive system and the forward belt drive system are coordinated such that only one belt drive system may be engaged at a time. The vehicle also has a foot pedal operatively connected to a pivotable shaft configured to selectively engage the forward and reverse belt drive systems. Pressing down on a forward portion of the foot pedal rotates the shaft in a first direction to engage the forward belt drive system such that rotation of the output pulley causes the input

pulley to rotate the input shaft of the transaxle in a first direction to drive the vehicle in a forward direction. Pressing down on a rear portion of the foot pedal rotates the shaft in a second direction to engage the rear belt drive system such that rotation of the output pulley causes the input pulley to rotate the input shaft of the transaxle in the opposite direction to drive the vehicle in a reverse direction.

[0007] These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The structure, operation, and advantages of the presently disclosed embodiment of the invention will become apparent when consideration of the following description taken in conjunction with the accompanying drawings wherein: [0009] FIG. 1 is a perspective view of a vehicle having a belt drive control system according to the invention;

[0010] FIG. 2 is an exploded perspective of the belt drive control system of the vehicle of FIG. 1;

[0011] FIG. 3 is schematic plan view of a portion of the belt drive control system of FIG. 2;

[0012] FIG. 4 is schematic side view of the portion of the belt drive control system of FIG. 3;

[0013] FIG. 5 is schematic plan view of a portion of the belt drive control system of FIG. 2 showing movement for reverse operation;

[0014] FIG. 6 is schematic side view of the portion of the belt drive control system of FIG. 5;

[0015] FIG. 7 is schematic plan view of a portion of the belt drive control system of FIG. 2 showing movement for forward operation;

[0016] FIG. 8 is schematic side view of the portion of the belt drive control system of FIG. 7;

[0017] FIG. 9 is schematic side view of the portion of the belt drive control system of FIG. 2 that interacts with the brake system of the vehicle; [0018] FIG. 10 is a schematic plan view of a portion of the transaxle; and

[0019] FIG. 11 is another schematic plan view of a portion of the transaxle.

[0020] Corresponding reference characters indicate corresponding parts throughout the views of the drawings.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS [0021] The invention will now be described in the following detailed description with reference to the drawings, wherein preferred embodiments are described in detail to enable practice of the invention. Although the invention is described with reference to these specific preferred embodiments, it will be understood that the invention is not limited to these preferred embodiments. But to the contrary, the invention includes numerous alternatives, modifications and equivalents as will become apparent from consideration of the following detailed description.

[0022] Referring now to the drawings, FIG. 1 shows a vehicle, such as a lawn and garden tractor or riding mower, generally indicated at reference number 10. The vehicle 10 includes a prime mover such as an internal combustion engine 12 mounted to a structural frame or chassis 14. The vehicle 10 includes left and right drive wheels 16 located toward the rear of the vehicle 10 and right and left front ground- engaging wheels 18. As seen in FIG. 2, the chassis 14 has fixably mounted thereto by any conventional means a transaxle 20 which may perform the function of a gear box, transaxle and brake. Extending transversely from each side of the transaxle 20 is a drive axle 19 fixably mounted to a respective drive wheel 16 by any conventional means. The engine 12 is operatively connected to the transaxle 20 with a belt drive control system 21 to provide locomotion to the vehicle 10 as will be described below. [0023] As best seen in FIG. 1 , the chassis 14 also supports an operator station comprising a seat 22. A steering input member 24 and a speed input member 28 are located near the seat 22 so that they are accessible to the operator of the vehicle 10.

The steering input member 24 provides steering inputs and may take the form of a conventional steering wheel. However, it is expressly noted that the steering wheel 24 may be another suitable steering control mechanism chosen with sound engineering judgment including, but not limited to a steering rod or joystick (not shown). According to the invention, the speed input member 28 is desirably a foot pedal and regulates the direction and speed of the vehicle 10 in the forward and reverse directions. The foot pedal 28 is desirably mounted on a single shaft 30 such that the foot pedal 28 is rocked forward using the foot by pressing down on a forward portion 32 of the foot pedal 28 to select forward drive, or rocked backward by pressing down on a rear portion 34 of the foot pedal 28 to select reverse drive. Although the illustrated embodiment shows the speed input member as being a foot pedal, one skilled in the art will understand that the speed input member may also be a hand control lever without departing from the scope of the invention. Desirably, the foot pedal 28 is biased toward a central position, corresponding to a neutral or stationary condition. A brake pedal 36 is also located near the seat 22 and configured to engage a brake system to brake the vehicle 10 via means known in the art. The brake system desirably interacts with the belt drive control system 21 such that the brake can be set in a parking brake mode only when the control system is in a neutral condition or the brake system forces the control system into the neutral condition when set. [0024] Turning also now to FIGS. 3 and 4, the details of the improved single lever control system for the belt driven vehicle 10, generally designated by reference number 21, is illustrated. An output double-stacked pulley 42 is mounted on a drive shaft (not shown) of the engine 12 in any manner commonly known in the art. The transaxle 20 has an input pulley 44 for receiving input torque from the engine 12. The input pulley 44 is a double-stacked pulley connected to the input shaft 46 (FIG. 2) of the transaxle 20. Torque is supplied by the single lever control system 21 to the transaxle input pulley 44 through either a forward belt drive system 100 or a reverse belt drive system 200. The forward belt drive system 100 operatively connects a first sheave 102 of the output pulley 42 on the drive shaft to a first sheave 104 of the input pulley 44 on the input shaft 46. The reverse belt drive system 200 connects a second

sheave 202 of the output pulley 42 to a second sheave 204 of the input pulley 44. The forward belt drive system 100 rotates the input shaft 46 of the transaxle 20 in a first direction to drive the vehicle 10 in a forward direction and the reverse belt drive system 200 rotates the input shaft in the opposite direction to drive the vehicle in a reverse direction.

[0025] In the illustrated embodiment, the forward belt drive system 100 includes a conventional variator pulley 106 and double idler pulleys 108, 110. As best seen in FIG. 3, a first forward belt 112, desirably a v-belt, connects the first sheave 102 of the output pulley 42 of the engine 12 to a lower sheave 114 of the variator pulley 106 for selective rotation of the variator pulley 106. A second forward belt 120, desirably a v-belt, connects an upper sheave 122 of the variator pulley 106 to the first sheave 104 of the input pulley 44. As is known, the center pulley half in the lower sheave 114 and upper sheave 122 may be movable axially to form variable diameter pulleys. Axial movement of the center pulley half changes the effective drive ratio between the first and second forward drive belts 112, 120 and, as a result, the forward speed of the vehicle 10. Double idler pulleys 108, 110 and tensioning spring 130 mounted between the chassis 14 and idler arm 132 provide a suitable and generally constant tension in the second forward belt 120. The variator pulley 106 rotates around an axle 134 mounted on a pivoting variator bracket 142. Pivoting movement of the variator bracket 142 controls the tension of the first forward belt 112 to vary the forward speed of the vehicle 10 as will be described below. However, tension in the second forward belt 120 may be maintained with any means common in the industry using sound engineering judgment. For example, the forward belt drive system 100 may have a fixed variator pulley and an additional rotating idler pulley that is controlled in a similar manner as the pivoting variator pulley in the illustrated embodiment.

[0026] In the illustrated embodiment, the reverse belt drive system 200 comprises a reverse belt 203, desirably a v-belt, wound around a first fixed pulley 204 and a second pulley 206 mounted on a pivoting bracket 208. The reverse belt 203 connects the second sheave 202 of the output pulley 42 on the drive shaft to the

second sheave 204 of the input pulley 44. The second pulley 206 rotates around an axle 214 mounted on the pivoting bracket 208. Desirably, the reverse belt 203 is wound such that the flat back side of the reverse v-belt 203 engages the second sheave 204 of the input pulley 44. Pivoting movement of the bracket 208 controls the tension of the reverse belt 203 as will be described below. As can be seen, the reverse belt 203 is wound such that the reverse belt drive system 200 is configured to rotate the input pulley 44 in the opposite direction than the forward belt drive system 100. [0027] Referring back to FIG. 2, a pivotable shaft 300 is conventionally connected to the chassis 14 of the vehicle 10 such that it extends transversely across the chassis 14. Operatively connected to the shaft 300 is the foot pedal 28 such that pressing down on the forward portion 32 of the foot pedal 28 rotates the shaft 300 in a first direction and pressing down on the rear portion 34 of the foot pedal 28 rotates the shaft 300 in a second direction. Two cams 302 and 304 are conventionally mounted on the shaft 300. The first cam 302 is a forward direction control cam and the second cam 304 is a reverse direction control cam.

[0028] Turning now to FIGS. 5 and 6, the reverse direction control cam 304 has a cam slot 306 formed therein. Cam follower 308 is slideably mounted within the cam slot 306. The cam follower 308 is conventionally pivotally mounted to one end of a cam link 310. The opposite end of the cam link 310 is connected to a tab 311 on the reverse bracket 208. In the illustrated embodiment, the distal end of the cam link 310 desirably comprises a coil spring 312. The coil spring 312 controls the tension in the reverse belt drive system 200. Without this spring 312, the tension in the reverse drive system 200 would be a matter of how much pressure the user applies on the foot pedal 28. The reverse bracket 208 is conventionally pivotally mounted to the chassis 14 at pivot point 314. Spring 316 biases the reverse bracket 208 to a neutral position (shown with solid lines) in which the pulley 206 (FIG. 3) mounted on the reverse bracket 208 is positioned to slack the reverse belt 203 such that the reverse belt 203 slips with respect to the second sheave 202 of the output pulley 42 and the second sheave 204 of the input pulley 44, and therefore does not cause the input pulley 44 to rotate the transaxle input shaft 46.

[0029] As shown in FIG. 6, movement of the foot pedal 28 in the reverse direction rotates the shaft 300 in the counter-clockwise direction. This rotation causes the reverse cam 304 to rotate such that the cam follower 308 reaches the end of the cam slot 306 and then move with the reverse cam 304. Movement of the cam follower 308 causes the reverse bracket 208 to pivot via the cam link 310 against the biasing force of the spring 316 (as shown in phantom in FIGS. 5 and 6). As the reverse bracket 208 pivots, the pulley 206 mounted on the reverse bracket 208 tensions the reverse belt 203. As the reverse belt 203 is tensioned, rotation of the output pulley 42 is transmitted to the input pulley 44, thus driving the transaxle shaft 46 in the reverse direction. Desirably, the flat back face of the reverse belt 203 engages the second sheave 204 of the input pulley 44. This engagement permits some slippage of the belt 203 relative the input pulley 44 when the belt 203 is only under moderate tension. Pressing down further on the reverse portion 34 of the foot pedal 28 causes the reverse bracket 208 to pivot further, therefore creating greater tension in the reverse belt 203. This greater tension results in less slippage of the reverse belt 203 relative the input pulley 44, and therefore a greater speed in the reverse direction. Accordingly, this belt arrangement of the reverse belt control system 200 provides some ability for the operator to vary the speed of the vehicle 10 in the reverse direction by varying the distance the foot pedal 28 is moved away from the neutral position in the reverse direction.

[0030] As previously mentioned, the forward direction control cam 302 is also operatively mounted on the shaft 300. The forward direction control cam 302 likewise has a cam slot 356 for receiving a cam follower 358. The cam follower 358 is attached to a forward direction control rod 360. The forward direction control rod 360 extends rearwardly toward the transaxle 20 and is operatively connected to the variator bracket 142. As best seen in FIG. 7, the variator bracket 142 is conventionally pivotally mounted to the chassis 14 at pivot point 364. A tension spring 366 is connected to a pin 367 at one end of the variator bracket 142. The other end of tension spring 366 is connected to chassis 14. The spring 366 biases the variator bracket 142 to a neutral position (shown with solid lines in FIG. 7). In this

neutral position, the variator pulley 106 mounted on the variator bracket 142 causes the first forward belt 112 to slack such that the first forward belt 112 slips with respect to the first sheave 102 of the output pulley 42 and the first sheave 114 of the variator pulley 106. Therefore, rotation of the output pulley 42 is not transmitted to the input pulley 44 to cause rotation of the transaxle input shaft 46. [0031] As shown in FIG. 8, movement of the foot pedal 28 in the forward direction rotates the shaft 300 in the clockwise direction. This rotation of the shaft 300 causes the forward cam 302 to rotate such that the cam follower 358 reaches the end of the cam slot 356 and then moves with the forward cam 302. Movement of the cam follow 358 causes the variator bracket 142 to pivot via the forward direction control rod 360 against the biasing force of the spring 366 (as shown in phantom in FIGS. 7 and 8). As the variator bracket 142 pivots, the variator pulley 106 tensions the first forward belt 112. As the first forward belt 112 is tensioned, rotation of the output pulley 42 is transmitted to the input pulley 44 via the variator pulley 106, thus driving the transaxle shaft 46 in the forward direction. Pressing down further on the forward portion 32 of the foot pedal 28 changes the belt pitch diameters between belts 112 and 120 and therefore a greater rotational speed transmitted by belt 120 to the input pulley 44. Accordingly, this arrangement provides the ability for the operator to vary the speed of the vehicle 10 in the forward direction by selecting the amount of movement of the foot pedal 28 in the forward direction.

[0032] Cams 302 and 304 and cam slots 356 and 306 are particularly designed to complement each other and to coordinate the engagement of the forward and rear belt drive systems 100, 200 with the foot pedal 28. Specifically, the profiles of the cam slots 356, 306 are designed such that only one of the forward and reverse drive systems 100, 200 can cause the input pulley 44 to rotate at a time. When the foot pedal 28 rotates in the forward or clockwise direction, the cam follower 308 slides in the slot 306 in the reverse cam 304 such that the reverse drive system 200 stays in its neutral condition. Likewise, when the foot pedal 28 rotates in the reverse or counterclockwise direction, the cam follower 358 slides in the slot 356 in the forward cam 302 such that the forward drive system 100 stays in its neutral condition. Therefore,

the two systems 100, 200 do not compete and attempt to rotate the input pulley 44 in opposite directions at the same time. The cams 302 and 304 and cam slots 356 and 306 are desirably designed such that there is a suitable dwell or delay when shifting from the forward to the reverse direction and vise versa.

[0033] Turning now back to FIG. 2 and additionally to FIG. 9, it is desirable that a brake system of the vehicle 10 interact with the single lever control system 21 such that the control system is locked in a neutral position when a parking brake feature of the brake system is engaged. In one embodiment, the brake pedal 36 is operatively attached to a second shaft 400 that extends transversely across a portion of the chassis 14 adjacent the shaft 300. A parking brake arm 402 is mounted on the shaft 400. Spring 404 is attached to the arm and biases the shaft into a position that disengages the brake system. Pin 408 is mounted on one end of the arm 402. When the brake pedal 36 is engaged to operate the brake system and set the parking brake, pin 408 is received in a notch 410 in a bracket 412 mounted on the shaft 300. The notch 410 is only aligned to receive the pin 408 when the shaft 300 is in its neutral position. Therefore, the parking brake feature can only be engaged when the single lever control system 21 is in its neutral condition. One skilled in the art will understand that other known means of prevent the pedal 28 from moving when the vehicle 10 is in a park mode or for only enabling the parking brake feature when the control system 21 is in a neutral condition may be used using sound engineering judgment without departing from the scope of the invention.

[0034] At times it is desirable to roll the vehicle 10 without having to put the vehicle in drive. In order to allow convenient manual movement of vehicle 10 even though belt drive system remains engaged with all driven and drive pulleys, a clutch mechanism 500 is provided as shown in FIGS. 10 and 11, to allow disengagement of input shaft 46. As shown in representative manner in FIG. 10, a clutch collar 504 is normally biased with spring 506 to engage a bevel gear 508 in the transaxle 20. A hand lever 510 is connected to the clutch collar 504 such that the clutch collar may be disengaged from the bevel gear 508 as shown in FIG. 11 to disengage the transaxle

gearing from the belt drive system and allow the vehicle to be pushed or moved without resistance. Such movement will rotate axles 19.

[0035] While this invention has been described in conjunction with the specific embodiments described above, it is evident that many alternatives, combinations, modifications and variations are apparent to those skilled in the art. Accordingly, the preferred embodiments of this invention, as set forth above are intended to be illustrative only, and not in a limiting sense. Various changes can be made without departing from the spirit and scope of this invention. [0036] What is claimed is: