Patent Application
20220192095
The disclosed subject matter relates to a mower propulsion apparatus that includes a split transaxle. More particularly, the disclosed subject matter relates to a fluid power transaxle that includes a motor portion that is movable relative to a fixed pump portion.
Self-propelled lawnmowers can be configured for the user to walk behind the lawnmower, ride on the lawnmower, or ride on a sulky trailered to the lawnmower. A riding lawnmower (also referred to as ride-on lawnmower or a ride-on mower) can include three or more wheels and can be driven by at least one of the wheels. The wheels can be rigidly connected to the main frame. Alternatively, at least one of the wheels can be connected to the frame by a suspension member with or without a damper assembly connected to the suspension member and the main frame.
Self-propelled lawnmowers can include different types of propulsion systems such as but not limited to an internal combustion engine or all electric zero turn riding (ZTR) mowers that drive a geared transmission directly connected to the engine or connected by a belt and pulleys, or drives a continuously variable transmission that uses a belt and adjustable pulleys, or drives a hydrostatic transmission. The propulsion apparatus can drive one of the wheels, or more than one of the wheels of the lawnmower.
A hydrostatic transmission can use hydraulic pressure to drive at least one of the wheels of the lawnmower. The hydrostatic transmission can include a pump that supplies pressurized hydraulic fluid to a hydraulic motor. The pressurized hydraulic fluid can act on fluid driven structure(s) of the motor to cause the motor to rotate the drive wheel(s) of the lawnmower and propel the lawnmower. The pump can be driven by the internal combustion engine or electric motor, etc.
Some embodiments of the presently disclosed subject matter are directed to a ride-on mower that can include a main frame, a side member pivotally connected to the main frame, and a transaxle. The transaxle can include a pump portion including a pump housing fixed on the main frame and a fluid displacement structure located in the pump housing, a motor portion including a motor housing and a fluid driven structure located in the motor housing, the motor housing being separate from the pump housing, and the motor housing being carried on and movable with the side member, and tubing interconnecting the pump portion and the motor portion.
Further embodiments are directed to a self-propelled lawnmower that can include a main frame, a power source attached to the main frame, a mower deck connected to the main frame and including at least one cutting chamber, at least one blade located in each cutting chamber, a plurality of wheels connected to the main frame, a suspension member connected to the main frame, the suspension member configured to move with respect to the main frame, and the suspension member configured to rotationally support at least one of the wheels, and a transaxle. The transaxle can be configured to selectively drive at least one of the wheels, and can include one of an operating pump and motor pump fixed on the main frame, an other of the operating pump and the motor pump fixed on the suspension member, such that the motor pump moves with respect to the operating pump when the suspension member moves relative to the main frame, and tubing interconnecting the operating pump and the motor pump. The motor pump could include or be replaced with an electric drive motor.
Additional embodiments are directed to a lawnmower that can include a main frame, a power source mounted on the main frame, a cutting chamber connected to the main frame, at least one blade located in the cutting chamber, a pair of suspension arms having a first end and extending to a second end, the first end is pivotally connected to the main frame such that each of the suspension arms pivots with respect to the main frame, a pair of dampers connected to the main frame, each of the dampers is connected to the second end of a respective one of the suspension arms, a pair of drive wheels rotatably supported by the suspension arms, and a first transaxle. The first transaxle can include, a pump portion including a pump housing fixed on the main frame and a fluid displacement structure located in the pump housing, a motor portion including a motor housing and a fluid driven structure located in the motor housing, the motor housing being spaced from the pump housing, the motor housing being carried on and moving with the respective one of the suspension arms, and the fluid driven structure being connected to and selectively driving a respective one of the drive wheels, and tubing interconnecting the pump portion and the motor portion.
The disclosed subject matter of the present application will now be described in more detail with reference to exemplary embodiments of the apparatus and method, given by way of example, and with reference to the accompanying drawings, in which:
A few inventive aspects of the disclosed embodiments are explained in detail below with reference to the various figures. Exemplary embodiments are described to illustrate the disclosed subject matter, not to limit its scope, which is defined by the claims. Those of ordinary skill in the art will recognize a number of equivalent variations of the various features provided in the description that follows.
A ride-on lawnmower can include at least one steerable wheel and at least one driven wheel. The steerable wheel can pivot relative to a frame of the lawnmower in order to change the direction of travel of the lawnmower when moving forward or backward.
An alternate embodiment of a ride-on lawnmower can include a pair of independently driven wheels such as tires, tracks, or other known ground driving mechanisms. An operator can control the direction of travel by controlling the direction in which each drive wheel is driven. For example, to travel forward along a straight path, the operator can cause both drive wheels to be driven in the same rotational direction and at the same rotational speed. The operator can steer the lawnmower by causing one of the drive wheels to rotate faster in the same direction as compared to another one of the wheels. Further, the operator can cause the lawnmower to spin about a yaw axis by causing one of the drive wheels to rotate in a first rotational direction and the other of the drive wheels to rotate in a second rotational direction that is opposite to the first rotational direction. This type of ride-on lawnmower can be referred to as a zero turn radius (“ZTR”) lawnmower or as a zero turn lawnmower.
In order to improve operator comfort, the drive wheel(s) can be suspended from a frame of the lawnmower with a suspension assembly that includes at least one moveable linkage and a damper such as a shock absorber, spring, spring with damper, strut, etc. The drive wheel(s) can be supported by a common suspension member. Alternate embodiments can include a suspension assembly for each drive wheel such that each drive wheel can move independently of the other drive wheel. The drive wheels can be configured as a rim with rubber tire located thereon. Alternatively, the drive wheels can be configured as a drive rim (or drive gear) that work in cooperation with at least one other drive rim or drive gear with a track fitted thereabout, such as are known in other tracked vehicles such as snowmobiles, bulldozers, etc.
Exemplary embodiments of a ride-on lawnmower can include a hydrostatic transmission (HST) or drive motors. The lawnmower with steerable wheels can include a single HST that drives at least one wheel. The ZTR lawnmower can include a pair of HST's or drive motors, one for each drive wheel. Each HST or drive motor can include an input pulley that is driven by a belt that is driven by an output pulley connected to a source of torque such as an internal combustion engine, electric motor, hybrid motor or other known power source. The source of torque can also be referred to as a power source.
The hydrostatic transmission(s) can be mounted on the suspension member(s) such that the HST moves with the suspension member. As a result, the input pulley of the HST can move relative to the output pulley. This relative movement can stretch and/or twist the belt and can cause the belt to disengage from one or both of the pulleys. This relative movement can cause extra wear on the drive belt that can adversely impact the operational life of the drive belt, and can also cause damage to the HST itself due to harsh movements during operation.
The lawnmower 10 can include the main frame 12, a mower deck 14, a seat 16, a pair of drive wheels 18L, 18R, a pair of caster wheels 20L, 20R, a pair of control levers 22, 24, a pair of front forks 26L, 26R, a pair of suspension assemblies 28, 30 and a power source 32. The left drive wheel 18L is omitted from
Referring to
The mower deck 14 can be referred to as a deck, a deck assembly, a blade deck, a cutter housing, or a cutter housing assembly. Referring to
Referring to
The power source 32 can be an internal combustion engine, an electric motor or a hybrid of an internal combustion engine and an electric motor. The power source configured as an internal combustion engine or a hybrid power source can have the engine output power source axis PSA oriented in the vertical direction V of the lawnmower 10.
The drive output pulley 52 can have a propulsion belt 53 connected thereto that turns various idler pulleys as well as a power input pulley 503 connected to the operating pump 501 of a split transaxle (401, 501) power system. A separate transaxle (401, 501) can be connected to each of the wheels 18L and 18R to drive each wheel in a forward or reverse direction depending on input from the control levers 22, 24 located adjacent the lawnmower's seat 16. The propulsion belt 53 can be configured to provide a constant rotational input to the input pulley 503 of each transaxle. Thus, both the speed and the direction of rotation of each wheel 18L, 18R are controlled by the control levers 22, 24. The control levers 22, 24 can be connected to a respective swashplate in an operating pump 501 of each respective split transaxle (or to an other mechanical, hydraulic, pneumatic, or electrical mechanism that can control speed and rotational direction in a transaxle).
As show in
The operating pump 501 can include a cooling fan 502 that is connected to a drive shaft that includes power input pulley 503. The input pulley 503 is driven by the propulsion drive belt 53 which is connected to the drive output pulley 52 connected to the output shaft of the power source 32. Thus, the input pulley 503 can be driven at a constant speed by the power source 32 of the lawnmower 10. The input pulley 503 drives fluid displacement structures located within the housing of the operating pump 501, such that the fluid displacement structures rotate about an operating pump axis MA and move fluid into/out of the operating pump 501 via output and return lines 421, 422. The speed and direction at which fluid travels within the operating pump 501 and motor pump 401 determines the speed and direction of rotation of the wheel 18R. Thus, control lever 24 can be connected to a mechanism, for example a swash plate located in the operating pump 501, that causes fluid within the pump 501 to change speed and/or direction.
The fluid arriving at the motor pump 401 via output line 421 drives fluid driven structures located within the housing of the motor pump 401, such that the fluid driven structures rotate about a motor pump axis MPA which results in rotation of the wheel shaft 412 and wheel hub 410. The wheel shaft 412 rotates about a wheel axis WA that can be coaxial with the motor pump axis MPA or about a wheel axis that is spaced from or at an angle with respect to the motor pump axis MPA.
The output line 421 and return line 422 can be connected to the operating pump 501 by an operating pump adapter 550 that can be configured as an attachment block. The output lines 421, 422 can each be configured as a hose and can include a hose connector 551 that connects the output line 421,422 in fluid communication with the operating pump adapter 550. If desired, the operating pump adapter 550 can be rotatably attached to the housing of the operating pump 501 such that if/when the output line 421 and return line 422 move with respect to the operating pump 501 the connection juncture between the lines 421, 422 and the housing of pump 501 will not significantly bend or be subject to adverse wear conditions. Similarly, output line 421 and return line 422 can be connected to the motor pump 401 by a motor pump adapter 450 that can be configured as an attachment block. The output lines 421, 422 can each include a hose connector 451 that connects each output line 421,422 in fluid communication with the motor pump adapter 450. If desired, the motor pump adapter 450 can be rotatably attached to the housing of the motor pump 401 such that if/when the output line 421 and return line 422 move with respect to the motor pump 401 the connection junctures between the lines 421, 422 and motor pump 401 will not significantly bend or be subject to adverse wear conditions. One or both of the motor pump adapter 450 and operating pump adapter 550 can be configured to rotate about an axis that is parallel with the wheel axis WA and pivot axis PA. Thus, the attachment adapters 450, 550 can rotate in a manner that prevents the rotational movement of the suspension assembly 30 to impart force onto the connection between each line 421, 422 and its respective attachment structure connected to the housings of the motor pump 401 and operating pump 501, respectively.
The motor pump 401 can be attached to the motor mount 308 portion of the suspension assembly 30 via fasteners 314 that extend through mount holes 309 located in the motor mount 308. The motor pump 401 can be operatively connected to an output such as wheel shaft 412 that in turn is connected to a wheel hub 410. Thus, when operating pump 501 drives the motor pump 401, the wheel shaft 412 is driven resulting in rotation of the wheel hub 410 and wheel 18R. The wheel shaft 412 can extend through a wheel hub throughway 310 in the motor mount 308. The wheel 18R can be connected to the wheel hub 410 via threaded attachment posts 411 extending from a face of the wheel hub 410.
By contrast, the operating pump 501 can be attached to the frame 12 via fasteners 514 connected to the mount plate 570 such that the operating pump 501 does not move with respect to the frame 12 of the lawnmower 10. In other words, the suspension assembly 30 (or 28) is configured such that the motor pump 401 (fixedly connected to the suspension assembly 30) is moveable with respect to the operating pump 501 (fixedly connected to the frame 12). Relatively flexible hosing can be used for the output line 421 and return line 422 to provide a fluid connection between the operating pump 501 and motor pump 401 such that the above-noted relative motion can occur between the operating pump 501 and motor pump 401. Although the relative motion is shown as a rotational motion about pivot axis PA, it is contemplated that the disclosed split transaxle can be used with different types of suspension assemblies. For example, it is possible to use a suspension assembly in which linear movement occurs between the operating pump 501 and motor pump 401 (when the lawnmower 10 traverses a bump or other obstacle), or in which a more complex non-linear movement occurs between the operating pump 501 and motor pump 401 (when the lawnmower 10 traverse a bump or other obstacle).
The arm 307 and motor mount 308 can be formed from a stamped metal part such that sufficient rigidity is provided to the suspension assembly 30. A wheel hub throughway 310 can be located in the motor mount 308 and can be surrounded by mount holes 309 such that fasteners 314 can pass therethrough to attach the motor pump 401 and wheel hub 410 to the motor mount 308. When assembled, the wheel shaft 412 of the wheel hub 410 passes through the throughway 310 of the motor mount 308. The stamped metal can be curved to form a lower mount bend 312 that can be connected to the damper 330 via fastener 332. A removable mount bracket 301 can be located opposite the mount bend 312 to form a bracket through which the fastener 332 extends and connects the damper 330 to the motor mount 308 of the suspension assembly 30. Fasteners 313 can extend through the bend 312 and fixedly connect the removeable mount bracket 301 to the motor mount 308. An upper mount bracket 331 and fastener 333 can be located at an opposite end of a longitudinal axis of the damper 330 to connect the upper end of the damper 330 to the frame 12 of the lawnmower 10. Fasteners 313, 333 and mount brackets 301, 331 can be configured to allow for some amount of rotation about the longitudinal axis of the fasteners 313, 333 which is substantially perpendicular to the longitudinal axis of the damper 330.
While certain embodiments of the invention are described above, it should be understood that the invention can be embodied and configured in many different ways without departing from the spirit and scope of the invention.
For example, while the arm 307 and motor mount 308 are depicted as being manufactured using stamped metal parts, the structures can be formed using various other materials and methods. For example, the arm 307 and motor mount 308 can be made using injection molding, casting, blow molding, extrusion, and other methods for forming structural components. The materials can be metal, metal compounds, plastics, ceramics, and even paper based product materials. The geometrical configuration for the arm 307, motor mount 308, and collar 302 can vary widely depending on the particular application. For example, the arm 307 and motor mount 308 can be I-beam or A-arm shaped, can be simple planar components (instead of the three-dimensional box configurations shown in the drawings), can be curved, straight along their entire length or other configuration that may be necessary to fit the dimensional and strength requirements for a particular application. There may also be several arms and several pivots mounted longitudinally or laterally that allow for various positions for the drive wheel 18L or 18L. Although the embodiments depicted in the drawings show the suspension arms 307 in the form of a trailing arm type suspension assembly, the suspension members can be formed in various other manners and still fall within the scope of the disclosed subject matter. For example, suspension members can be spaced out to the side instead of rearward such as in an A-arm suspension member configuration. The suspension members can also be configured as double wishbone type suspension elements, sliding pillar elements, lateral arms, dual trailing arms, swing arms, forward extending arms, or other known independent suspension member structures and still fall within the scope of the presently disclosed subject matter. Three-link, and four-link suspension components are also contemplated for use as suspension members in the presently disclosed subject matter.
The knuckle 702 includes a wheel hub 410 connected thereto that allows wheel 18L to rotate about an axis that is substantially or completely perpendicular to the longitudinal axis (or forward driving axis) of the vehicle (lawnmower 10). The wheel hub 410 can include a plurality of attachment posts 411 for connecting the wheel 18L to the wheel hub 410. The lower portion of the knuckle 702 can be connected to two laterally extending support members: middle suspension bar 77; and lower suspension bar 78. The middle suspension bar 77 can be rotatably connected at its distal end to the knuckle 702 via middle mount 75 that allows for rotation about an axis that is at a slight angle with respect to the longitudinal axis (forward driving axis) of the lawnmower 10. The middle suspension bar 77 can be rotatably connected at its proximal end to the vehicle frame 12 via a frame mount 707 that allows for rotation about an axis that is at a slight angle with respect to the longitudinal axis (forward driving axis) of the lawnmower 10. The lower suspension bar 78 can be rotatably connected at its distal end to the knuckle 702 via middle mount 74 that allows for rotation about an axis that is at a slight angle with respect to the longitudinal axis (forward driving axis) of the lawnmower 10. The lower suspension bar 78 can be rotatably connected at its proximal end to the vehicle frame 12 via a frame mount 708 that allows for rotation about an axis that is at a slight angle with respect to the longitudinal axis (forward driving axis) of the lawnmower 10. A damper 30 is shown as connected to the A-arm at an end close to the wheel mount structure and knuckle 702. However, the damper 30 could also be connected to the knuckle 702 itself or to other structural members of the suspension assembly.
In this exemplary embodiment, the motor pump 401 can be directly connected to the knuckle 702 to drive the wheel hub 410 and rotate the tire 18L. The motor pump 401 will thus move with the knuckle 702 and wheel 18L as they traverse ground obstacles. The motor pump 401 can be connected via output line 421 and return line 422 to operating pump 501 which is attached to the vehicle frame 12. Thus, the operating pump 501 and motor pump 401 form a split transaxle, with the operating pump 501 and its associated weight and geometrical limitations removed and spaced from the knuckle 702. Of course, as noted above, other types of side extending suspensions are contemplated for use with this type of split transaxle that would fall within the scope of the presently disclosed subject matter, such as dual A-arm configurations, 3-link, and 4-link suspensions, as well as other known side extending suspensions. The split transaxle configuration of the presently disclosed subject matter could even be included in a lawnmower 10 that does not have a suspension system, and in which the wheels 18L and 18R are directly connected to the frame 12 itself. In this case, the operating pump 501 can be located somewhere more convenient on the frame 12 than at the wheel 18L.
In another embodiment, the housing for the motor pump 401 itself can be directly fastened to or welded to the arm 307 to form the suspension assembly 30. The damper 330 can also be welded to or fastened directly to the motor pump 401. Any of the fasteners disclosed herein can be replaced with other known attachment structures such as rivets, welds, adhesives, clamps, etc.
Exemplary embodiments are intended to include or otherwise cover any location for the split transaxle, provided one of the motor pump 401 and operating pump 501 is located on any portion of the suspension assembly 30 that is moveable with respect to the remainder of the lawnmower 10 (e.g., the frame 12 or components that are fixedly attached to the frame such that the components do not move relative to the frame 12), and the other of the motor pump 401 and operating pump 501 is fixedly attached to the remainder of the lawnmower 10. Thus, although the drawings show the motor pump 401 located at an end of the suspension assembly 30 located adjacent damper 330, the motor pump 401 could be located anywhere along the arm 307 or immediately adjacent to the collar 302. The lines 421, 422 (which can be hydraulic lines or power supply cables) extending between the motor pump 401 and operating pump 501 (which can be a hydraulic pump motor in the case of hydraulic lines or an electric motor in the case of power supply cables) can be made from various materials and configured in various shapes depending on application. For example, the lines 421, 422 could run within the arm 307 and through collar 302 in a protected environment and then through a protected conduit attached to the frame 12, if necessary. The lines 421, 422 can be construed of various materials, including plastic or polymeric material hoses, reinforced hoses (reinforced with metal webbing, tungsten, plastic webbing, carbon fiber, etc.), and other known hydraulic line materials. When lines 421, 422 are configured as power cables, the cables can be made from any commonly known or not yet know material for a power supply cable, such as steel, copper, aluminum or other known conductive metals or materials.
While the operating pump 501 is shown as being driven by a propulsion drive belt 53 that is connected to power source 32, the operating pump 501 can be powered in other ways and still be within the scope of the present disclosure. For example, the belt 53 can be replaced with a gear train connected to a power take off of the power source 32. Alternatively, a direct drive motor (electric, internal combustion, or hybrid motor) can be provided at each of the operating pumps 501 to power each operating pump 501. Further, the power source 32 can have a single operating pump 501 attached thereto that then has two pairs of lines 421, 422 extending therefrom to a respective left and right motor pump 401 located on the left and right suspension assembly 28, 30, respectively. Thus, a single operating pump 501 could be used in certain applications to power both left and right side motor pumps 401.
Although the propulsion belt 53 and blade drive belt 54 are depicted as oriented to rotate in a horizontal plane such that each of the pulleys 52, 56, 58, 503 rotate about a vertical axis that is substantially perpendicular to the pivot axis PA and wheel axis WA (and parallel with the power source axis PSA and operating pump axis MA), the orientation can be different for one or both of the belts 53, 54 and pulleys 52, 54, 56, 58, 503.
While the subject matter has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention.
