Patent Publication Number: US-9403435-B2

Title: Adjustable ground speed control devices, systems, and methods for walk-behind equipment

Description:
TECHNICAL FIELD 
     The subject matter disclosed herein relates generally to variable control systems for powered equipment. More particularly, the subject matter disclosed herein relates to variable speed controls and methods for walk-behind working machines, such as lawnmowers. 
     BACKGROUND 
     Many walk-behind working machines, such as lawnmowers and other similar small powered equipment, have a self-propel system that propels or drives the working machine at a selected ground speed. In such systems, a control system is typically carried on the handle to allow the operator to engage and disengage the self-propel system and to select a desired ground speed. For example, many such control systems use a pivotable ground speed control bail on the handle of the working machine. Generally, self propelled drive systems can be divided into two categories: single/multiple speed, and variable speed. In single/multiple speed drive systems, the ground speed is fixed by one or more gear ratios, and it can only be adjusted by selecting a different gearset (if available). In contrast, variable speed drive systems allow the operator the ability to “infinitely” adjust the ground speed of the lawn mower, such as by a slipping belt system where the belt tension is varied, a slipping clutch system where the clutch pressure is varied, a hydrostatic transmission where a swash plate angle is variable, or an electric drive system where the electric power supply is switched. 
     Even in such variable speed drive systems, however, the maximum operating speed is either fixed or, if variable, cumbersome to change while the working machine is being operated. Specifically, in all currently available adjustable control drive systems, the maximum speed setting is made by a mechanical lever, rotary knob, or mechanical latching device. In such configurations, an operator must remove at least one of his hands from the control handle to make any adjustments to the maximum operating speed. Accordingly, making such adjustments can result in the operator at least partially losing some degree of control over the working machine. In view of these issues, it would be desirable for a ground speed control system to allow for adjustment of the maximum speed setting of the working machine without diminishing the operator&#39;s ability to control the working machine. 
     SUMMARY 
     In accordance with this disclosure, adjustable ground speed control devices, systems, and methods for walk-behind equipment are provided. In one aspect, a variable speed control system for a walk-behind working machine is provided. The variable speed control system can include a control system base, one or more control lever that is selectively movable with respect to the control system base between a first operating position and a second operating position, first and second speed adjustment actuators positioned on the control system base proximal to the one or more control lever, and a control unit configured for communication with the one or more control lever, the first and second speed adjustment actuators, and a machine component. In this configuration, the control unit can be configured to selectively control the operation of the machine component between a minimum operating speed and a variable maximum operating speed, the variable maximum operating speed having a variable value, where the first speed adjustment actuator can be configured to increase the value of the variable maximum operating speed (e.g., up to a system maximum speed), and the second speed adjustment actuator can be configured to decrease the value of the variable maximum operating speed. The one or more control lever can be configured to control the machine component to operate at the minimum operating speed when the one or more control lever is in the first angular position, and the one or more control lever can be configured to control the machine component to operate at the variable maximum operating speed when the one or more control lever is in the second angular position. 
     In another aspect, a method for varying a speed of a walk-behind working machine is provided. The method can include moving one or more control lever with respect to a control system base between a first operating position and a second operating position and, without releasing the one or more control lever, selectively actuating one of a first speed adjustment actuator or a second speed adjustment actuator positioned on the control system base proximal to the one or more control lever. In this way, pivoting the one or more control lever to the first operating position can control a machine component to operate at a minimum operating speed, whereas pivoting the one or more control lever to the second operating position can control the machine component to operate at a variable maximum operating speed, wherein a value of the variable maximum operating speed is variable. Further, actuating the first speed adjustment actuator can increase the value of the variable maximum operating speed, and actuating the second speed adjustment actuator can decrease the value of the variable maximum operating speed. 
     Although some of the aspects of the subject matter disclosed herein have been stated hereinabove, and which are achieved in whole or in part by the presently disclosed subject matter, other aspects will become evident as the description proceeds when taken in connection with the accompanying drawings as best described hereinbelow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the present subject matter will be more readily understood from the following detailed description which should be read in conjunction with the accompanying drawings that are given merely by way of explanatory and non-limiting example, and in which: 
         FIG. 1 a    is a perspective view of a variable speed control system in a first operating position according to an embodiment of the presently disclosed subject matter; 
         FIG. 1 b    is a perspective view of a variable speed control system in a second operating position according to an embodiment of the presently disclosed subject matter; 
         FIG. 2  is a schematic representation of a drive system for a self-propelled machine according to an embodiment of the presently-disclosed subject matter; 
         FIG. 3  is a block diagram illustrating a system for adjusting a maximum operating speed of a self-propelled machine according to one aspect of the subject matter described herein; and 
         FIG. 4  is a front view of a variable speed control system according to an embodiment of the presently disclosed subject matter. 
     
    
    
     DETAILED DESCRIPTION 
     The present subject matter provides variable speed control systems and methods for walk-behind working machines, such as lawnmowers and similar powered machines. In one aspect, the present subject matter provides variable speed control systems and methods that can vary speed, comfortably hold a fixed speed, and vary the maximum speed at which the working machine is operated. 
     Specifically, for instance, as shown in  FIGS. 1 a    through  2 , a variable speed control system, generally designated  100  can comprise a handle  110  configured to be gripped by an operator to control the operation of a working machine, such as a lawnmower or other small powered machine, to which handle  110  is connected. A control system base  120  can be attached to or otherwise positioned near handle  110 . A display  122  can be provided on control system base  120  to provide warnings or other indications of the operating state of the working machine, and an engine engagement control  124  (e.g., a push-button starter). A pair of control levers, generally designated  130   a  and  130   b,  can be movably attached to control system base  120 . With this general configuration, control levers  130   a  and  130   b  can be moved to control operation of a machine component, such as for example a variable transmission for a self-propel system of the working machine. 
     In particular, a first control lever  130   a  can comprise a first lever arm  132   a  having a first end that is pivotably attached to control system base  120  (e.g., about a pivot axis that extends through control system base  120 ) and a second end substantially opposing the first end that comprises a first grip portion  134   a.  Likewise, a second control lever  130   b  can comprise a second lever arm  132   b  having a first end that is pivotably attached to control system base  120  and a second end substantially opposing the first end that comprises a second grip portion  134   b.  Specifically, for example, as shown in  FIGS. 1 a    and  1   b,  each of first and second control levers  130   a  and  130   b  can have a substantially L-shaped profile, with first and second grip portions  134   a  and  134   b  extending at a non-zero angle (e.g., between about 50 and 90 degrees) away from first and second lever arms  132   a  and  132   b,  respectively. This angular arrangement allows the operator to grab one or both of first or second grip portions  134   a  or  134   b  in a comfortable hand position and pivot first and second control levers  130   a  and/or  130   b  with respect to control system base  120 . In some embodiments, first and second lever arms  132   a  and  132   b  can be coupled for rotation together, whereby pivoting of one of first or second lever arms  132   a  or  132   b  (e.g., by pressing on a respective one of first and second grip portions  134   a  or  134   b ) causes a corresponding movement of the other. Alternatively, first and second lever arms  132   a  and  132   b  can be independently movable with respect to control system base  120  such that the operation of either (or both) of first and second lever arms  132   a  and  132   b  can be moved to control operation of a machine component. 
     In this regard, to control the operation of the associated machine component (e.g., a self-propel system), first and second control levers  130   a  and  130   b  can be selectively pivoted with respect to control system base  120  between a first angular position (See, e.g.,  FIG. 1 a   ) at which first and second grip portions  134   a  and  134   b  of first and second control levers  130   a  and  130   b  are spaced apart from handle  110  and a second angular position (See, e.g.,  FIG. 2 b   ) at which first and second grip portions  134   a  and  134   b  are drawn against handle  110 . Further in this regard, in some embodiments, when in the second position, at least a portion of each of first and second grip portions  134   a  and  134   b  is positioned within a recess that is formed in an edge of handle  110 . 
     In any configuration, the movement of first and second control levers  130   a  and  130   b  between the first and second angular position can involve pivoting the control lever through a limited angular range (e.g., about 35 degrees) such that the movement of first and second control levers  130   a  and  130   b  can be comfortably performed by the operator without letting go of handle  110 . In other words, while the operator is holding handle  110  to steer or otherwise control the working machine, the operator can extend his/her thumbs and/or palms backwards a short distance (e.g., about 71 mm) to grab one or both of first and second grip portions  134   a  and  134   b  while keeping his/her other fingers on handle  110 . 
     Further in this regard, a first speed adjustment actuator  140   a  and a second speed adjustment actuator  140   b  can also be provided on control system base  120 . First and second speed adjustment actuators  140   a  and  140   b  can be used in combination with first and second control levers  130   a  and  130   b  to further control the operating state of the working machine. In the configuration shown in  FIGS. 1 a    and  1   b,  for example, first and second speed adjustment actuators  140   a  and  140   b  can comprise push buttons positioned proximal to first and second control levers  130   a  and  130   b,  respectively. In this arrangement, an operator can easily reach and depress the push buttons while holding handle  110  and/or first and second control levers  130   a  and  130   b.  In particular, first and second speed adjustment actuators  140   a  and  140   b  can be positioned adjacent to a natural thumb position of an operator when the operator is manipulating first and second control levers  130   a  and  130   b.  In the configuration shown in  FIGS. 1 a    and  1   b,  for example, such a positioning results in first speed adjustment actuator  140   a  being positioned at or near a right-most edge of control system base  120  such that it is near to first control lever  130   a,  and second speed adjustment actuator  140   b  is positioned at or near a left-most edge of control system base  120  such that it is near to second control lever  130   b.  Alternatively, first and second speed adjustment actuators  140   a  and  140   b  can be provided in any of a variety of other forms, including by not limited to a tactile switch, a capacitance sensor, a membrane with capacitance sensing, or any other device that is sensitive to touch. In any configuration, variable speed control system  100  can be designed to be easily manipulated while the operator maintains overall control of the working machine. 
     In operation, where the machine component is a self-propel system for a working machine, moving first and second control levers  130   a  and  130   b  to the first angular position can control the machine to be in a first operating state, which can be a minimum operating speed or a disengaged state (i.e., no torque applied). Conversely, upon movement of first and second control levers  130   a  and  130   b  to the second angular position, the machine component can be controlled to be in a second operating state. Again, for instance, where the machine component is a self-propel system for a working machine, the second operating state can be a fully engaged or high speed state (i.e., torque applied to the drive system such that the working machine is moved at a selected cruising speed). 
     Furthermore, those having skill in the art will recognize that first and second control levers  130   a  and  130   b  can additionally be pivoted to any of a variety of intermediate angular positions to correspondingly operate the machine component in one or more partial engagement states (e.g., low- to medium-speed operating states of the self-propel system). In this way, the operator can selectively operate the machine component at states between the first and second operating states. For example, where the machine component is a self-propel system, positioning first and second control levers  130   a  and  130   b  at a selected intermediate position can control the self-propel system to operate at a speed that is proportional to the relative angular travel of first and second control levers  130   a  and  130   b  between the first and second operating states. At any position, however, first and second control levers  130   a  and  130   b  can be configured to be comfortably held and manipulated by the operator while maintaining a grip on handle  110 . 
     Furthermore, first and second speed adjustment actuators  140   a  and  140   b  can provide additional control over the range of operating states available. In particular, first and second speed adjustment actuators  140   a  and  140   b  can be configured to adjust the value of a parameter of the output at the second operating state of the machine component. Again, in the case where the machine component is a self-propel system for a working machine, for example, this adjustment allows the maximum operating speed setting of the self-propel system to be adjusted based on the preferences of the operator. 
     In one embodiment, for example, first speed adjustment actuator  140   a  can be operable to change the maximum operating speed setting of the self-propel system to have an incrementally higher value, whereas second speed adjustment actuator  140   b  can be operable change the maximum operating speed setting of the self-propel system to have a decrementally lower value. In this way, fine adjustments of the maximum operating speed setting of the working machine can be made without diminishing the operator&#39;s ability to control the working machine. 
     The control inputs from first and second control levers  130   a  and  130   b  and first and second speed adjustment actuators  140   a  and  140   b  can then be communicated to the operation of the working machine. In some embodiments, for example, the working machine can utilize a hybrid system, such as is illustrated in  FIG. 2 , in which the working element (e.g., a blade when working machine is a lawn mower) is driven by a combustion engine, generally designated  150 , and the self propelled drive system, generally designated  160 , is driven by an electric motor  162  that is configured to supply power to one or more wheels  164  of the self-propelled machine at a selected forward ground speed. Drive system  160  can be mechanically driven by engine  150  directly, or as shown in  FIG. 2 , drive system  160  can be electrically driven, and the operation of drive system  160  can be controlled by the operation of a control unit  200  (e.g., an electronic control unit (ECU)) that is in communication with both engine  150  and variable speed control system  100 . 
     In some aspects, for example, drive system  160  can comprise an electric transmission, and electric motor  162  can be an electric transmission motor that is powered using an electrical actuator or generator  155  or any other type of rotating object (and/or a battery where engine  150  is not running). In some aspects, electrical actuator or generator  155  can be coupled and/or mounted onto a crankshaft of engine  150 . Electric motor  162  can be adapted to directly power drive system  160 , and drive system  160  can be adapted to transfer and/or supply power directly to the one or more wheels  164  of the self-propelled machine. 
     As discussed above, variable speed control system  100  can be configured to be operable by an operator to select a desired ground speed of the self-propelled machine. In particular, the desired ground speed can be selectively chosen by the operator through manipulation of variable speed control system  100 , such as by moving first and second control levers  130   a  and  130   b  to any of a range of operating positions corresponding to one of a predetermined range of desired ground speeds. This operability advantageously allows an operator to choose a ground speed that best suits the terrain and/or the operator&#39;s mobility, among other factors. Furthermore, the value of the cruising/maximum operating speed corresponding to the second angular position of first and second control levers  130   a  and  130   b  (i.e., fully-depressed against handle  110 ) can be adjusted up or down by operating first and second speed adjustment actuators  140   a  and  140   b.  In this way, users who desire to operate the self-propelled machine at lower speeds do not need to carefully hold first and second control levers  130   a  and  130   b  at an unstable intermediate operating position between the fully disengaged and fully engaged states. Rather, such users can simply change the maximum operating speed setting using first and second speed adjustment actuators  140   a  and  140   b,  and then move first and second control levers  130   a  and  130   b  to the fully engaged position. This adjustability thus allows the operator to pick a maximum operating speed that can be easily and consistently achieved without continuously adjusting the position of first and second control levers  130   a  and  130   b.    
     In this way, the desired ground speed can be selected by the operator, with variable speed control system  100  being configured to transmit the selected desired ground speed, in the form of a signal or pulse, to drive system  160  via control unit  200 . For example, variable speed control system  100  can be configured to transmit an electrical signal or pulse (e.g. a control signal) to control unit  200  by way of an electrical sensor. Variable speed control system  100  can alternatively be configured to transmit a digital or analog signal to control unit  200 , while other alternative means of communication can also be utilized. In one aspect, the control signal can communicate the desired ground speed to control unit  200  essentially as a ratio of the desired ground speed compared to a system maximum ground speed setting (e.g., which can be equal to or greater than the user-defined maximum operating speed setting controlled by first and second speed adjustment actuators  140   a  and  140   b ). Under normal operating conditions, control unit  200  can be configured to control drive system  160  to drive the self-propelled machine at the desired ground speed selected by way of variable speed control system  100 . 
     Control unit  200  can correspondingly be configured to receive the control signal from variable speed control system  100 . Based at least partly on this input, control unit  200  can transmit power to drive system  160  via electric motor  162 , thereby controlling the transmission speed or actual ground speed of the self-propelled machine (e.g., by driving wheels  164 ). For example, control unit  150  can be configured so that the control signal can be transmitted as a signal or pulse to a microcontroller  210 . In one aspect, engine power can be communicated to control unit  200  as alternating current or AC power. Where engine  150  is configured to communicate AC power to control unit  200 , then control unit  200  must convert AC power to DC power before reaching electric motor  162 . In one aspect, for example, engine  150  transmits power to a rectifier  202  or any other device that converts alternating current (AC) to direct current (DC). After power has been converted from AC power to DC power, a DC power bus  204  can communicate said power in the form of a signal or pulse to a power delivery system, generally designated  206 , in order to control the power supplied to electric motor  162 . Power delivery system  206  can comprise that of a pulse width modulator or (PWM), a potentiometer, or a rheostat. 
     In one particular configuration, for example, the control inputs from first and second speed adjustment actuators  140   a  and  140   b  can be communicated to and interpreted by control unit  200  in the process shown in  FIG. 3 . As illustrated in  FIG. 3 , actuation of first speed adjustment actuator  140   a  can communicate a speed increase signal  302   a  to control unit  200 , whereas actuation of second speed adjustment actuator  140   b  can communicate a speed decrease signal  302   b  to control unit  200 . An input reception step  310  can thus include control unit  200  receiving these inputs, and a comparison step  320  can include identifying whether one of speed increase signal  302   a  or speed decrease signal  302   b  is being communicated. Specifically, control unit  200  can test whether a speed increase is requested (e.g., in a speed increase comparison step  322   a ) or a speed decrease is requested (e.g., in a speed decrease comparison step  322   b ). In some embodiments, a double-input check  312  can be performed before comparison step  320  to avoid unnecessary changes in the maximum operating speed setting when both of first and second speed adjustment actuators  140   a  and  140   b  are operated simultaneously. 
     When only a single input is provided, however, if a speed increase is requested (i.e., speed increase comparison step  322   a  returns a true value), control unit  200  can further determine whether increasing the maximum operating speed setting would cause the system to exceed a system maximum setpoint (e.g., manufacturer-set maximum speed) in a maximum comparison step  330   a.  If an increase would not exceed the system maximum setpoint, a speed increment step  340 a can increase the maximum operating speed setting. If the maximum operating speed setting already equals the system maximum setpoint, no change is made. 
     Alternatively, if a speed decrease is requested (i.e., speed decrease comparison step  322   b  returns a true value), control unit  200  can further determine whether decreasing the maximum operating speed setting would cause the system to fall below an established system minimum setpoint in a minimum comparison step  330   b.  If a decrease would not bring the system below this value, a speed decrement step  340   b  can decrease the maximum operating speed setting. If the maximum operating speed setting is already at the system minimum setpoint, no change is made. 
     The maximum operating speed established by this or by another process can be displayed to the operator to identify the current setpoint at which the working machine is operating and to provide visual feedback to the operator with respect to how the actuation of first and second speed adjustment actuators  140   a  and  140   b  affect the maximum operating speed setting. As shown in  FIG. 4 , for example, a speed setting indicator  123  can be provided on display  122  to graphically indicate the current setpoint of the maximum operating speed within the range of possible values (e.g., between a system minimum setpoint and a system maximum setpoint discussed above). In this regard, speed setting indicator  123  can be provided as one of an LED display, and LCD display, an array of indicator lights, or any of a variety of other display devices known to those having skill in the art as being able to convey a value and/or relative speed setting within a given range. 
     In some aspects, the subject matter described herein may be implemented in software in combination with hardware and/or firmware. For example, the subject matter described herein may be implemented in software executed by a processor (e.g., a hardware-based processor), microprocessor, and/or microcontroller of the electronic control unit. In one exemplary implementation, the subject matter described herein may be implemented using a non-transitory computer readable medium having stored thereon computer executable instructions that when executed by the processor of a computer control the computer to perform steps. Exemplary computer readable media suitable for implementing the subject matter described herein include non-transitory devices, such as disk memory devices, logic devices, logic transistors, chip memory devices, programmable logic devices, such as field programmable gate arrays, and application specific integrated circuits. In addition, a computer readable medium that implements the subject matter described herein may be located on a single device or computing platform or may be distributed across multiple devices or multiple computing platforms. 
     The present subject matter can be embodied in other forms without departure from the spirit and essential characteristics thereof. The embodiments described therefore are to be considered in all respects as illustrative and not restrictive. Although the present subject matter has been described in terms of certain preferred embodiments, other embodiments that are apparent to those of ordinary skill in the art are also within the scope of the present subject matter.