Operator platform isolation system

A vehicle for terrain travel includes a chassis, an operator platform including space for footing, a first isolation mechanism and a second isolation mechanism operably connected between the chassis and the operator platform. The isolation mechanisms are to be placed either below, above or level with the operator platform and at substantially opposite edges of the operator platform. Each isolation mechanism at least partially absorbs motion from the chassis. The isolation mechanisms may be made up of telescopic members, a biasing member or a dampening device. One of the isolation mechanisms may provide pivotal coupling of the operator platform to the chassis and at least partially absorb motion from the chassis.

FIELD OF INVENTION

This present invention relates to a suspension system for at least partially isolating an operator platform from the motion of a vehicle chassis.

BACKGROUND OF THE INVENTION

An operator of a vehicle traveling on the ground may experience a bumpy ride due to the unevenness of a terrain. The vehicle may transmit the motion arising from the rise and fall of the wheels directly to the operator. To resolve such a problem, certain vehicles are equipped with suspension systems. A conventional suspension system, as shown in U.S. Pat. No. 6,460,318 to Ferris et al., operates by providing a chassis that floats relative to the wheels so that the chassis will be at least partially isolated from the movement of the wheels. However, such suspension systems still cause significant motion of the chassis which in turn is experienced by the operator. Other devices, such as one disclosed in U.S. Pat. No. 5,037,155 to Holm et al., attempt to reduce the transmission of motion by installing a suspension system that spans the base of an operator seat. However, the motion of the vehicle may still be felt by the operator through the legs which feel the movement of the chassis. Thus, there is a need to further isolate the operator from the motion of the chassis and to provide a smoother ride than is realized by existing suspension systems.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, a vehicle for terrain travel comprises a chassis, an operator platform including space for footing, and a first isolation mechanism and a second isolation mechanism operably connected between the chassis and the operator platform. The isolation mechanisms are to be placed below, above or level with the platform and at substantially opposite borders of the operator platform. Each isolation mechanism at least partially absorbs motion from the chassis and at least one of the isolation mechanisms couples the operator platform to the chassis.

In accordance with another aspect of the present invention, a vehicle for terrain travel comprises a chassis, an operator platform and an isolation mechanism between the chassis and the operator platform. The isolation mechanism is placed near one edge of the operator platform and performs the dual functions of pivotally coupling the operator platform to the chassis and at least partially absorbing motion from the chassis.

DESCRIPTION OF EXAMPLE EMBODIMENTS

The present invention will now be described referring to a number of example embodiments shown in the drawings where like numerals refer to like elements. It is to be appreciated that the embodiments are shown for illustration only and that the limitations of the embodiments should not be considered as defining the bounds of the present invention.

The present invention may be found in any type of vehicle that travels in contact with the surface of a terrain. Such a vehicle will commonly travel the terrain by way of wheels but vehicles using other means such as continuous chain treads (i.e., caterpillar), ski-like parts or any combination of the above mentioned means can also benefit from the present invention. Thus, the present invention is applicable to means of travel such as riding mowers, golf carts, harvesters, all-terrain vehicles, snowmobiles and jet skis.

FIG. 1shows an engine-propelled lawn mower1with wheels. The mower1shown is a transmission steer or zero turn radius mower that can pivot as it turns and, compared to a mower operated through a conventional steering wheel mechanism, results in less uncut grass over which the mower must pass again. The major components of the mower inFIG. 1are a chassis2, front wheels4, rear wheels6, a cutting deck8, a deflector shield10, an operator platform12, an operator seat14, a left wheel housing16, a right wheel housing18and an engine20.

In the embodiment shown inFIG. 1, the front wheels4are caster wheels that are free to rotate about a vertical axis while the rear wheels6drive the mower1and are operably connected to a transmission (not shown) and the engine20mounted to the rear of a chassis2. The present invention can be implemented on mowers with different wheel arrangements such as a mower having rear drive wheels and steerable front wheels or a mower having traction and steering drive wheels mounted to the chassis such that the rear of the chassis may be supported by one or more free caster wheels and a front mounted deck may be supported by one or more free caster wheels. The transmission steer mower is equipped with steering levers22in front of the operator to control turning. Pushing a lever rotates the wheel on that particular side of the lever in a forward direction while pulling the lever rotates the wheel in a rearward direction. A hand brake24is located to the left of the operator seat14. It is to be appreciated that the implementation of the present invention is not limited to transmission steer mowers but also applies to all types of riding mowers as well as other types of vehicles.

In the embodiment ofFIG. 1, the cutting deck8is connected to the bottom of the chassis2and is hauled by the forward movement of the chassis2. The cutting deck8travels the terrain on anti-scalping rollers26and houses a cutter (not shown) that is powered by the engine20. Although the cutting deck8is located directly underneath the chassis2, the present invention is compatible with alternative locations of the cutting deck8. The cutter may also be operably connected to a collector to which grass will be channeled after they are cut. The engine20is mounted at the rear of the chassis2behind the operator seat14. A fuel tank (not shown) is found adjacent to the engine20inside the left wheel housing16with a fuel cap28at the top. The wheel housings16,18can also be equipped with a fuel gauge30, a headlight31, a cupholder32and other mower control devices such as a throttle lever. In a mower operated by a conventional steering wheel mechanism, the engine20is often located at the front end of the chassis2but the present invention can still be implemented on a chassis2with varying arrangements of the engine20and other components.

The present invention is applicable to any ground traveling vehicle with the operator platform12comparable to that ofFIGS. 1 and 2. The operator platform12lies over a substantial portion of the chassis2unoccupied by the engine20. The operator platform12provides a foundation, distinct from the chassis2and the operator seat14, on which all of the operator's weight can rest. In this regard, a platform without an operator seat14would qualify as an operator platform12if it provided a foundation on which the operator could place one's feet or stand. Furthermore, the operator platform12can be substantially planar or take on a variety of shapes such as the substantially stepped structure ofFIG. 3. The general plane of the operator platform12can also be substantially tilted or horizontal. The embodiment ofFIGS. 2 and 3provides a stepped platform12where the operator can either be seated or standing and where the operator seat14is mounted on an upper area13aof the stepped operator platform12. If the operator chooses to stand, he or she can stand by placing his or her feet on a lower area13bof the stepped operator platform12. As shown inFIG. 1, the lower area13bof the foundation has a plurality of perforations15for discarding dirt or grass. The operator seat14may be attached fixedly on top of the operator platform12or may be isolated from the motion of the operator platform12by way of biasing members or dampening devices. As shown inFIG. 1, the operator seat14is also equipped with armrests17and the hand brake24and the steering levers22are easily within the reach from the operator seat14. The steering levers22can be swiveled sideways to allow the operator to take a seat or to lift the operator platform12. The swiveling of the steering levers22also may function as a safety feature for starting operation of the mower1.

FIGS. 2 and 3Ashow one embodiment of the present invention in which the operator platform12is connected to the chassis2through a set of isolation mechanisms. In this embodiment, an operator platform isolation system40is made up of a front isolation mechanism42and a rear isolation mechanism54as shown inFIG. 3A. Each isolation mechanism is operably connected between the chassis2and the operator platform12and contributes to isolating the operator platform12from the motion of the chassis2that is caused as the wheels4,6move over uneven terrain. However, it is to be appreciated that, even though the isolation mechanisms42and54are operably connected between the chassis2and the operator platform12, their locations may be either below, level with, or even above the operator platform12in appearance. In the embodiment shown inFIGS. 3A and 3B, the front isolation mechanism42is made up of two isolating members43that are made up of telescopic members44a,44band a biasing member45that intervenes the telescopic members44a,44b. The telescopic members44are coaxial tubes of distinct diameters with overlapping sections that are designed to slide relative to one another extending or compressing the overall length of the cylinder-like isolating member43that is formed. The biasing member45, such as a coil spring, intervenes in that it is held in place between flanges46a,46bof the telescopic members44a,44b. The telescopic members44a,44band the biasing member45are of such dimensions that the length of overlapping portion of the telescopic members44a,44bwould be greater had it not been for the presence of the biasing member45between the telescopic members44a,44b. At the outer ends47a,47bof the cylinder-like isolating member43, the telescopic members44a,44bhave apertures48a,48bfor pivotally coupling ring-shaped ends47a,47bto the chassis2and the operator platform12. As shown inFIGS. 1,2,4and5, the lower end47bof the isolating member43of the front isolation mechanism42is pivotally coupled to joints51of the chassis2via bolt and nut. The upper end47aof the isolating member43of the front isolation mechanism42is pivotally coupled to the operator platform12through a rotating bar49that is perpendicularly bent at the outer ends50a,50b. The rotating bar12has a front end50aand a rear end50bboth of which are threaded to accept nuts. As shown inFIGS. 1,4and5, the front end50aof the rotating bar49pivotally couples the front isolation mechanism42to the operator platform12while a rear end50bof the rotating bar49is pivotally coupled to joints52of the chassis2.

FIGS. 2 and 3Aalso show the rear isolation mechanism54that is made up of two sets of two adjacent biasing members56, such as coil springs, all of which are in a substantially linear configuration and a stabilizer bar60. In this embodiment, the lower ends57bof the biasing members56are fixedly secured to the chassis2as shown inFIG. 4via bolt and nut. The upper ends57aof the biasing members56simply support the lower surface of the operator platform12while freely moving against it. However, it is possible to contemplate a rear isolation mechanism54where one end of a biasing member56is coupled to either the operator platform12or the chassis2while the other end simply contact the other or is coupled to the other. The stabilizer bar60, shown inFIG. 3C, is made up of telescopic members62a,62band may include an intervening biasing member or a dampening device within the telescopic members62a,62b. The stabilizer bar60has two ring-shaped ends63a,63bthat contain ball-and-socket joints64a,64bwhere an inner end63aof the stabilizer bar60is pivotally coupled to a threaded protrusion66at the rearmost end of the operator platform12while an outer end63bis pivotally coupled to the chassis2. The stabilizer bar60can change its length and adjust to the vertical and horizontal movement of the operator platform12. It is to be appreciated that other variations of the rear isolation mechanism54are within the scope of the present invention. Such variations include, among other things, a rear isolation mechanism made up of isolating members that are any combination of telescopic members, an intervening biasing member and an intervening dampening device instead of the present embodiment where biasing members and telescopic members are installed away from one another. Moreover, variations of the ends63a,63bof the stabilizer bar60include, among other things, loose tolerance pinned joints or other cheaper, conventional linkage connections such as a rubber ISO-mount or a plastic bushing.

It is to be appreciated that the location of the isolation mechanisms can be rearranged to produce varying effects in the isolation of the operator platform12from the chassis motion and that a variety of isolation mechanisms can be used instead of the embodiment shown inFIGS. 2 and 3A. For example, instead of isolation mechanisms42,54at the front and the rear borders of the operator platform12, isolation mechanisms may be installed on the left and right borders. The isolation mechanisms are installed at borders of the operator platform meaning that one isolation mechanism spans a segment of the operator platform rather than a point such as a corner of the operator platform. The locations of the isolation mechanisms are not limited strictly to opposing borders of the operator platform although such an arrangement is common in suspension systems and it is also possible to have more than two sets of isolation mechanisms. Moreover, variations of the isolation mechanisms would include a dampening device61(not shown) such as a shock absorber mounted inside the telescopic members44a,44bor62a,62bor a separate dampening device where the dampening device61dissipates the kinetic energy from the rising and falling motion of the operator platform12by turning it into heat energy through the compression of a hydraulic fluid inside the telescopic members44a,44bor62a,62busing a piston. Furthermore, a biasing member may be any type of spring such as rubber springs, air springs, leaf springs or torsion springs. The biasing member or the dampening device may also be made of elastomers or other polymeric materials.

As a result of the structure of the isolation mechanisms42,54, the operator platform suspension system40will operate in the following manner and as can be observed inFIGS. 1,4A-4C and5. In the front isolation mechanism42, the lower end47bof the isolating member43and the rear end50bof the rotating bar49will maintain a fixed position on the chassis2. In comparison, the upper end47aof the isolating member43whose movement coincides with the front end50aof the rotating bar49will move relative to the chassis2depending on the position of the operator platform12. The telescopic members44a,44bwill react to the movement of the operator platform12by sliding against each other and changing the overall length of the isolating member43. The upper end47aof the isolating member43will rotate about the lower end47bof the isolating member43while also changing the distance from the lower end47b. However, the upper end47aof the isolating member43will rotate about the rear end50bof the rotating bar49while maintaining a fixed distance from the rear end50b. In the rear isolation mechanism54, the lower end57bof the biasing member56, secured to the chassis2in the present embodiment, will maintain a fixed position on the chassis2while the upper end57aof the biasing member56moves freely relative to the lower surface of the operator platform12since it is simply in contact with the lower surface. As to the stabilizer bar60, the outer end63bwill maintain a fixed position on the chassis2while the inner end63amoves vertically as the protrusion66rises and falls due to the movement of the operator platform12. This will cause the telescopic members62a,62bto slide against each other and adjust the overall length of the stabilizer bar60. The stabilizer bar60will also adjust to the minimal horizontal movement of the protrusion66arising when the front end50aof the rotating bar49rotates about the rear end50bof the rotating bar49and the general plane of the operator platform12tilts.

FIGS. 4A,4B and4C show examples of the various positions of the operator platform isolation system40in operation.FIG. 4Ashows the operator platform12in a level position70relative to the chassis2. This is the default position for the operator platform12and another example of the operator platform12in the level position70is when the mower1is traveling at constant speed on an ideally flat surface.FIG. 4Bshows the operator platform12in an incline position72relative to the chassis2where the rear of the operator platform12is lower than in the level position70and a seated operator becomes closer to a supine position than in the level position70. An example of the operator platform12in the incline position72is when the rear wheels6of the mower1encounter a bump or when the mower1undergoes acceleration.FIG. 4Cshows the operator platform12in a decline position74relative to the chassis2where the front of the operator platform12is lower than in the level position70and a seated operator becomes closer to a prone position than in the level position70. An example of the operator platform12in the decline position74is when the front wheels4of the mower1encounter a bump or when the mower1undergoes deceleration.

FIG. 5shows the operator platform12in a raised position76. The pivotal coupling of the front isolation mechanism42allows the operator platform12to be rotatably lifted and provides easier access to components below or behind the operator seat14. The steering levers22must be removed from the path of the rotating operator platform12and the inner end63aof the stabilizer bar60must also be disconnected from the protrusion66of the operator platform12before the operator platform12is lifted. The possibility of lifting the operator platform12enables having storage space such as a trunk underneath the operator seat14and facilitates access to the engine1in case of maintenance activities.

FIG. 6shows examples of the variety of positional relationships that can be established between the chassis2and the operator platform12and, in addition, the positional relationships of the isolation mechanisms42,54in relation to the chassis2and the operator platform12. It is to be appreciated that the isolation mechanisms42,54inFIG. 6can represent any possible combination of telescopic member, biasing members, dampening device or any other means of isolating the operator platform12from motion of the chassis2. It is possible for the operator platform12to be above, below or level with the chassis2. Moreover, it is possible for the isolation mechanisms42,54to occupy other than the space directly between the chassis2and the operator platform12. It is also possible for the isolation mechanisms42,54to be indirectly connected to the operator platform12or the chassis2via certain linkage arrangements. The various positions of the isolation mechanisms42,54illustrate the fact that the operator platform12can be isolated from the motion of the chassis2in a way that the isolation mechanisms42,54operate at various angles, i.e., vertical, non-vertical or even horizontal.

FIG. 7illustrates an embodiment of the mower1in which an operator is in a standing position on top of the mower1rather than a seated position. The mower on which the operator can stand may accommodate both a seated position and a standing position or may accommodate only a standing position.

The main benefit of the operator platform isolation system40is that it allows the operator platform12to float separately from the chassis2and, as a result, the operator platform12is further isolated from the motion of the chassis2even if the chassis2is equipped with a separate suspension system. The motion of the chassis2that would have directly been transmitted to the operator platform12is further absorbed by the operator platform isolation system40. The present invention also enables a suspension system using springs that are relatively weaker than those for a suspension system connecting the wheels4,6with the chassis2because the suspension system does not need to bear the additional weight of the chassis2. Moreover, the present invention is an improvement over a suspension system that simply spans the base of the operator seat because a seat suspension generally uses a simple pivot mechanism, that is devoid of an isolation mechanism comparable to the present invention, through which the chassis motion can be transmitted and further because the operator, despite the seat suspension, can experience the chassis motion through his or her feet that are in contact with the chassis2. In comparison, the present invention better isolates the operator's body from the chassis motion.