Patent Publication Number: US-11022085-B2

Title: Engine operation detection system

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a National Stage Application of PCT/US2018/040086, filed Jun. 28, 2018, which claims the benefit of and priority to U.S. Provisional Application No. 62/526,824, filed Jun. 29, 2017, both of which are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     The present invention generally relates to internal combustion engines and sensors used to detect operation of such engines. More specifically, the present invention relates to an engine operation detection system for an engine. 
     For engines including an electronic fuel injection (EFI) system, there is a readily available signal that can be used to determine an engine operational state. For carbureted engines, this signal may not be readily available. To determine an engine operational state with a carbureted engine, the same data gathering systems that can be used to obtain the readily available signal from an EFI system cannot be used. Additionally, for engines with an EFI system that are from a third-party engine manufacturer, the engine run signal may also not be readily available. Accordingly, an engine operation detection system that can be used on all types of engines is desired. 
     SUMMARY 
     One embodiment relates to an engine operation detection system. The engine operation detection system includes an engine including a spark plug and a spark plug wire, and an engine run sensor including a signal wire including an antenna, the antenna configured to receive a spark plug signal from the spark plug wire, a data acquisition output wire outputting an engine on/off condition signal, a power supply providing power to the engine run sensing circuit, and an engine run sensing circuit configured to transform the spark plug signal into the engine on/off condition signal output via the data acquisition output wire. 
     Another embodiment relates to an engine run sensor. The engine run sensor includes a signal wire including an antenna, the antenna configured to receive a spark plug signal from a spark plug wire on an engine, a data acquisition output wire outputting an engine on/off condition signal, a power supply providing power to the engine run sensing circuit, and an engine run sensing circuit configured to transform the spark plug signal into the engine on/off condition signal output via the data acquisition output wire. 
     Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The disclosure will become more fully understood from the following detailed description, taken in conjunction with the accompanying figures, in which: 
         FIG. 1  is a schematic diagram of an internal combustion engine used on outdoor power equipment, according to an exemplary embodiment. 
         FIG. 2  is a schematic diagram of an engine operation detection system, according to an exemplary embodiment. 
         FIG. 3A  is a schematic view of an engine run sensor, according to another exemplary embodiment. 
         FIG. 3B  is a perspective view of the engine run sensor of  FIG. 3A . 
         FIG. 4  is a circuit diagram for an engine run sensing circuit of the engine run sensor of  FIGS. 3A-3B , according to an exemplary embodiment. 
         FIG. 5  is a circuit diagram for an engine run sensing circuit of the engine run sensor of  FIGS. 3A-3B , according to another exemplary embodiment. 
         FIG. 6  is a circuit diagram for an engine run sensing circuit of the engine run sensor of  FIGS. 3A-3B , according to another exemplary embodiment. 
         FIG. 7  is a section view along section line  7 - 7  of a connector of the engine run sensor of  FIGS. 3A-3B . 
     
    
    
     DETAILED DESCRIPTION 
     Before turning to the figures, which illustrate the exemplary embodiments in detail, it should be understood that the present application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology is for the purpose of description only and should not be regarded as limiting. 
     Referring to the figures generally, an engine operation detection system for use with outdoor power equipment is described. The engine operation detection system detects a spark plug pulse signal from an engine used with outdoor power equipment and transforms the spark signal into an engine operation indication using either an engine-on condition signal or an engine-off condition signal. The engine operation indication is transmitted to an engine monitoring system (e.g., for transmission to a fleet management system) for display to an operator, for calculation of productivity statistics, engine efficiency values, operator efficiency values, production of maintenance schedules, etc. Outdoor power equipment includes lawn mowers, riding tractors, snow throwers, fertilizer spreaders, salt spreaders, chemical spreaders, pressure washers, portable air compressors, tillers, log splitters, zero-turn radius mowers, walk-behind mowers, wide area walk-behind mowers, riding mowers, stand-on mowers, pavement surface preparation devices, industrial vehicles such as forklifts, utility vehicles, commercial turf equipment such as blowers, vacuums, debris loaders, overseeders, power rakes, aerators, sod cutters, brush mowers, etc. 
     Referring to  FIG. 1 , an internal combustion engine used on outdoor power equipment is shown, according to an exemplary embodiment. The engine  112  includes an engine block  130  having a cylinder  132 , a piston  134 , and a crankshaft  136 . The piston  134  reciprocates in the cylinder  132  to drive the crankshaft  136 . The engine  112  further includes a fuel system having a fuel tank  114 , an air intake  116 , and a carburetor  118  or other air-fuel mixing device (e.g., electronic fuel injection, direct fuel injection, etc.). In the carburetor  118 , fuel from the fuel tank  114  is mixed with filtered air from the air intake  116  to produce an air/fuel mixture for combustion in a combustion chamber  120  of the engine  112 . 
     A spark plug  122  is positioned within the combustion chamber  120  and is configured to spark to ignite the air/fuel mixture in the combustion chamber  120 . In some embodiments, an ignition armature (not shown) is mounted proximate to a flywheel (not shown) so that magnets within the flywheel pass the ignition armature at specifically timed intervals, generating a high-voltage charge once per rotation of the flywheel. The charge is directed to the spark plug  122  via a spark plug wire  142  (shown in  FIG. 2 ) and used to ignite the air/fuel mixture. During operation of the engine  112 , the piston  134  is driven by the timed ignitions of the air/fuel mixture in the combustion chamber  120 , initiated by the spark plug  122 . After ignition, the spent fuel and air is released from the combustion chamber  120  and out of the engine  112  via an exhaust outlet  124 . The spark plug  122  includes an insulator  144  configured to prevent shorting between a center electrode and a ground electrode on the spark plug  122 . The insulator  144  surrounds the body of the spark plug  122 . 
     The outdoor power equipment  110  further includes an energy storage device  140  (e.g., electrical storage device) and an engine run sensor  150 . The energy storage device  140  is configured to provide power to the engine run sensor  150  and other components of the engine  112  and/or outdoor power equipment  110 . Accordingly, the energy storage device  140  is electrically coupled to the engine run sensor  150 . The energy storage device  140  may include one or more batteries, capacitors, or other devices. In some embodiments, the energy storage device  140  includes a removable and rechargeable lithium-ion battery. The battery may be charged at a charging station or may include a charging port integrated with the battery (e.g., battery pack with charging port to receive a connection from a wire coupled to an outlet or the charging station). The battery, in other embodiments, may alternatively plug directly into a wall outlet, or the charging station may be wall mounted or plug directly into a wall outlet. In other embodiments, the energy storage device  140  includes a lead-acid battery. In other embodiments, other battery chemistries may be used. 
     Referring to  FIG. 2 , an engine operation detection system  100  is shown, according to an exemplary embodiment. The outdoor power equipment  110  includes an engine run sensor  150  communicably coupled to an engine monitoring system  300 . The engine monitoring system  300  is communicably coupled to a fleet management system  400  such that the engine monitoring system  300  can transmit engine on/off condition data to the fleet management system  400 . The engine run sensor  150  is communicably and operatively coupled to the engine  112  and more specifically, to the spark plug wire  142 . The engine run sensor  150  is configured to detect whether the engine  112  is running (e.g., detecting an engine-on condition or an engine-off condition). The engine run sensor  150  is configured to receive inputs associated with the spark plug signal carried by the spark plug wire  142  (e.g., signal carried from the armature to the spark plug  122 ) and generate a digital output indicating an engine on- or off-condition (e.g., engine on/off signal). The engine run sensor  150  uses the spark plug signal to transform the battery voltage into an engine on/off signal, as described further herein. The engine run sensor  150  transmits the engine on/off signal to the engine monitoring system  300 . The engine monitoring system  300  may include or be a component of an outdoor power equipment fleet management system, such as the system disclosed in U.S. patent application Ser. No. 15/615,666 entitled “Fleet Management System for Outdoor Power Equipment,” the content of which is incorporated herein in its entirety. The engine monitoring system  300  can use the engine on/off signal to calculate engine runtime to determine various operating conditions and efficiencies of the equipment  110  and operators of the equipment  110 . As described further herein, the engine run sensor  150  may also generate a signal indicative of engine speed, which when received by the engine monitoring system  300 , can be used to determine further operating conditions of the engine  112 . 
     Referring to  FIGS. 3A-3B , the engine run sensor  150  includes an engine run sensing circuit  200  mounted on a printed circuit board and positioned within a housing  152  (e.g., flexible heat shrink circuit board jacket), a coaxial cable  153  positioned on one side of the housing  152  with a signal wire  154  and a grounding wire  156  extending therefrom, and a connector  158  on another side of the housing  152 . The signal and grounding wires  154 ,  156  are located on an opposite side of the housing  152  from the connector  158  to accommodate connecting the engine run sensor  150  with one or more wiring harnesses in an in-line arrangement. In some embodiments, the grounding wire  156  is optional to the operation of the engine run sensor  150 . In these embodiments, the grounding wire  156  may be cut off prior to installation of the sensor  150 . Additionally, the engine run sensing circuit  200  is relatively long and thin, further allowing for the in-line arrangement shown in  FIGS. 3A-3B . Accordingly, there is no need to mount the engine run sensor  150  directly to a mounting location on the engine  112  or outdoor power equipment  110 . Rather, the engine run sensor  150  essentially becomes a part of the wiring harness. In some embodiments, the circuit  200  is incorporated on a double-sided printed circuit board to allow for ease of incorporation into a wire harness. 
     The coaxial cable  153  is electrically coupled to the engine run sensing circuit  200  and extends from the housing  152  for a distance until the signal wire  154  and the grounding wire  156  extend separately from the coaxial cable  153 . The signal wire  154  and grounding wire  156  each include a splice (e.g., joint, connection) that acts as a connection (e.g., solder, crimp, ultrasonically weld, and covered by a waterproof material) for each wire  154 ,  156  to the coaxial cable  153 . The splices are covered by a heat shrink jacket, which also overlaps the coaxial cable  153 . The grounding wire  156  extends to a connector  160  that is secured to the engine block  130  or other ground via a fastener (e.g., bolt) for grounding purposes. 
     Referring to  FIGS. 2 and 3A , the end of the signal wire  154  is positioned proximate the spark plug wire  142  such that communication between the spark plug wire  142  (or the signal from the spark plug) and the signal wire  154  is established. The signal wire  154  acts an antenna  168  that receives the spark plug signals from the spark plug wire  142 , allowing for communication between the spark plug wire  142  and the signal wire  154  without direct connection. The signal wire  154  is looped at least once around the spark plug wire to form an antenna  168 . Accordingly, the antenna  168  includes a ring  178  with at least one loop. The spark plug signal passing through the antenna  168  creates a change in the electromagnetic field, which the antenna  168  converts to an electrical signal (e.g., input signal). In some embodiments, the signal wire  154  is wrapped around the spark plug wire  142  multiple times (e.g., three or four coils). The signal wire  154  receives electromagnetic signals from the spark plug  122  or spark plug wire  142  without being directly coupled thereto. In some embodiments as shown in  FIG. 2 , the signal wire  154  is included in (e.g., molded into) the insulator  144  of the spark plug  122 . In this way, an operator only needs to install the spark plug  122  into the engine without the additional step of positioning the signal wire  154  proximate the spark plug wire  142 . In other embodiments, the signal wire  154  is included in an alligator clip. In some embodiments, the signal wire  154  is a pre-wound loop of wire that is molded into an annular connector that can be attached to (e.g., slid over, fitted onto) the spark plug  122 . 
     The signal wire  154  carries an input signal indicative of the spark plug pulse signal to the engine run sensing circuit  200  for processing. The details of the components of circuit  200  are discussed below with regard to  FIG. 4 . The engine run sensing circuit  200  converts the received spark plug pulse signal into a digital output signal indicating high-voltage or low-voltage corresponding to either an engine-on condition or an engine-off condition. A voltage is detected from the spark plug signal and the signal is conditioned to be within a specific voltage range (e.g., 0 to 5 Volts (V)). Based on the received (and conditioned) voltage values, the digital output signal generates either a value of “1” which indicates an engine-on condition (e.g., high-voltage) or a value of “0” which indicates an engine-off condition (low-voltage). In other embodiments, these values may be switched (e.g., a value of “1” may indicate an engine-off condition, and so on). Smaller preset ranges within the voltage range (e.g., 0 to 5 V) are used by the circuit  200  to convert the specific voltage values into a binary/digital signal. For example, if the voltage detected from the spark plug signal is between 0 V and 0.8 V, the voltage would be considered a low-voltage and thus, would correspond to the engine-off condition. If the voltage is between 2 V and 5 V, the voltage would be considered a high-voltage and thus, would correspond to the engine-on condition. These example ranges are not to be limiting. 
     In some arrangements, the engine run sensing circuit  200  is configured as a digital-analog converter (e.g., frequency-to-analog converter), such that the circuit  200  converts the period/frequency of the received digital/binary spark plug signal (e.g., 1-bit digital signal) to an analog voltage proportional to engine speed. The output analog signal can include a voltage range proportional to a corresponding engine speed range. For example, the voltage may range between 0 and 5 V, where a voltage value of 2.4 V corresponds to an engine speed of 2400 revolutions per minute (RPM) and where a voltage value of 3.2 V corresponds to an engine speed of 3200 RPM. In this arrangement, the engine run sensing circuit  200  includes an integrator circuit. The integrator circuit collects pulses from ignition events in a capacitor, with a known leak from a resistor. The spark pulse frequency increases with engine speed. As such, with more spark pulses, the capacitor fills faster than the leak of electrons from the resistor. If the pulses are occurring faster than the resistor is leaking electrons, the voltage goes up and as such, the indicated proportional engine speed is higher. In other embodiments, a microcontroller or frequency-to-voltage integrated circuit is utilized to convert the pulse timing into a variable analog voltage. 
     Referring still to  FIGS. 3A-3B , on the opposite side of the engine run sensing circuit  200  (e.g., opposite side of the housing  152 ) from the coaxial cable  153 , output wires couple to and extend from the engine run sensing circuit  200  to a connector  158 . Between the engine run sensing circuit  200  and the connector  158 , the output wires are covered (e.g., wrapped) in a protective sheathing (e.g., flexible fire retardant heat shrink tubing). The output wires include a ground wire  180 , a data acquisition wire  182 , and a battery power wire  184  all electrically connected to the connector  158  and to the engine sensing circuit  200 . Referring to  FIG. 7 , the end of the connector  158  is shown, according to an exemplary embodiment. The connector  158  is a four-pin male connector including multiple pins  190  each electrically connected to one of the ground wire  180 , the data acquisition wire  182 , and the battery power wire  184 . The connector  158  couples to the engine monitoring system  300  to communicate the engine on/off condition signal from the engine run sensing circuit  200 . 
     Two rubber grommets  170  may be positioned within the housing  152  on each side of the engine run sensing circuit  200  to secure the wires (e.g., coaxial cable  153 , output wires  180 ,  182 ,  184 ) within the housing  152  such that movement of the wires is limited. 
     The engine on/off condition signal may be displayed on a visual indicator on either the engine  112  or the outdoor power equipment  100 . The engine on/off condition signal may also be displayed by the engine monitoring system  300  for use in a fleet management system (e.g., on an enterprise computing system or user mobile device included with a fleet management system). The engine on/off signal may also be stored in a memory (e.g., database) included with a fleet management system. 
     Referring to  FIG. 4 , a circuit diagram for the engine run sensing circuit  200  is shown, according to an exemplary embodiment. The signal wire  154  forming the antenna  168  is shown as coupled to the input of the circuit  200 . The grounding wire  156  (e.g., shield) is also shown as coupled to the input of the circuit  200 . The input of the circuit  200  couples by way of capacitor  202  to the base of transistor  204 . The collector of transistor  204  is coupled to the collector of transistor  210  and to the power supply  222  (e.g., battery power wire  184 ). The emitter of transistor  204  is coupled by way of a jumper  208  and resistor  212  to the base of transistor  210 . The transistor  204  acts to pull to low-voltage. 
     The collector of transistor  210  is coupled to the power supply  222  and the emitter of transistor  210  is coupled by way of resistor  220  to the output  224  (e.g., data acquisition wire  182 ). The transistor  210  acts to go to high-voltage. Resistor  220  acts to limit the current output in the case of the signal wire  154  touching ground. The input of the circuit  200  couples by way of capacitor  218 , resistor  216 , and Zener diode  214  to the output  224  and also couples to the battery ground  226  (e.g., battery ground wire  180 ). 
     The engine run sensing circuit  200  is configured to accommodate a variety of ignition systems and a range of spark signals (e.g., weak, strong). Accordingly, the circuit  200  includes transistors  204  and  210 , which when coupled in series, act to amplify the input when there is a weak signal received from the signal wire  154 . The circuit  200  includes a parallel resistor-capacitor (RC) circuit configured to smooth the pulse and a diode  206  and Zener diode  214  acting as a shunt to ground if the voltage has exceeded a threshold voltage. The diode  206  and Zener diode  214  also act as a full wave bridge rectifier to correct for the polarity of the signal. 
     Referring to  FIG. 5 , a circuit diagram for the engine run sensing circuit is shown, according to another exemplary embodiment. The signal wire  154  forming the antenna  168  is shown as coupled to the input of the circuit  500 . The grounding wire  156  (e.g., shield) is also shown as coupled to the input of the circuit  500 . The input of the circuit  500  couples by way of resistor  502  to the base of transistor  506 . The collector of transistor  506  is coupled to the base of transistor  514  by way of a jumper  508  and a resistor  512  and to the power supply  222  (e.g., battery power wire  184 ) via resistor  510 . The emitter of transistor  506  is coupled by way of capacitor  518  to the base of transistor  514 . 
     The collector of transistor  514  is coupled to the power supply  222  and the emitter of transistor  514  is coupled by way of jumper  516  and resistor  526  to the output  224  (e.g., data acquisition wire  182 ). Resistor  526  acts to limit the current output in the case of the signal wire  154  touching ground. The input of the circuit  500  couples by way of full wave bridge rectifier  504 , capacitor  506 , jumper  520 , resistor  522 , capacitor  524 , and resistor  526  to the output  224  and also couples to the battery ground  226  (e.g., battery ground wire  180 ). 
     Referring to  FIG. 6 , a circuit diagram for the engine run sensing circuit is shown, according to another exemplary embodiment. The input of the circuit  600  couples by way of resistor  602  to the base of transistor  606 . The collector of transistor  606  is coupled to the base of transistor  614  by way of a jumper  608  and a resistor  612  and to the power supply  622  (e.g., battery power wire  184 ) via resistor  610 . The emitter of transistor  606  is coupled by way of capacitor  618  to the base of transistor  614 . 
     The collector of transistor  614  is coupled to the power supply  222  and the emitter of transistor  614  is coupled by way of resistor  626  to the output  224  (e.g., data acquisition wire  182 ). Resistor  626  acts to limit the current output in the case of the signal wire  154  touching ground. The input of the circuit  600  couples by way of full wave bridge rectifier  604 , capacitor  606 , Zener diode  628 , Zener diode  630 , resistor  622 , capacitor  624 , and resistor  626  to the output  224  and also couples to the battery ground  226  (e.g., battery ground wire  180 ). Diode  630  is a transient-voltage-suppression (TVS) diode, which protects the circuit  600 , engine run sensor  150 , and system  100  from transient voltage spikes. 
     According to an exemplary embodiment, the circuits  200 ,  500 ,  600  shown in  FIGS. 4-6  are contained on non-programmable circuitry, circuit boards, or a processing circuit that are integrated with a component of the engine, and may be fully powered by the energy storage device  140  or other on-board source. Accordingly, the circuits  200 ,  500 ,  600  may require no electrical interface or connection to components of the outdoor power equipment aside from those carried by or integrated with the engine. No additional wiring or hook ups are required. Accordingly, the assembly process for the associated outdoor power equipment may be improved. 
     Alternatively, in accordance with another exemplary embodiment, the circuits  200 ,  500 ,  600  shown in  FIGS. 4-6  may be contained on non-programmable circuitry, circuit boards, or a processing circuit within the housing of the energy storage device and may be fully powered by the energy storage device (e.g., battery or other power source). As is known, energy storage devices generally have integrated circuitry contained therein that is configured to monitor operating variables of the energy storage device (current, voltage, etc.) related to its charge state. Thus, the addition of the circuits  200 ,  500 ,  600  of  FIGS. 4-6  to the existing circuit board(s) or on an additional circuit board within the housing of the energy storage device is possible. 
     In contemplated embodiments, the engine run detection system  100  may receive additional or different inputs used to detect various equipment and engine characteristics, such as input from a sensor configured to indicate whether the outdoor power equipment  110  has moved recently, engine operational parameters, such as temperature inputs, pressure inputs, etc. In contemplated embodiments, the system  100  may also provide a signal output to the operator, such as a visible indicator on a display coupled to the engine, to a handle or chassis of outdoor power equipment, or an audible alert. 
     The engine run sensor  150  is easily connected in-line with existing wiring, thereby eliminating the need for adding additional wiring or significantly rerouting wiring for outdoor power equipment. The engine run sensor  150  is relatively small in size and light weight. This allows the engine run sensor  150  to be connected to existing wiring and not physically mounted to any other component of the outdoor power equipment. That is, once connected to the existing wiring, the engine run sensor  150  is free to remain otherwise unsupported (e.g. dangle with the existing wiring harnesses) by a mount, bracket, or other physical support structure on the outdoor power equipment. 
     The construction and arrangements of the engine operation system, as shown in the various exemplary embodiments, are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. Some elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process, logical algorithm, or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present invention. 
     The present disclosure contemplates methods, systems and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions. 
     Although the figures may show or the description may provide a specific order of method steps, the order of the steps may differ from what is depicted. Also two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on various factors, including software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps.