Engine control system and method of automatic starting and stopping a combustion engine

An engine control system (10) operates off a microprocessor of an engine control module, ECM (62), which will automatically start a combustion engine (12) upon any one of a series of enabler signals (68, 67, 70) indicative of low battery voltage, low cab temperature and/or low engine temperature. The system (10) also includes safety measures which will override the automatic starting of the engine. For instance, the vehicle will not automatically start if a vehicle speed is detected, if the parking brake is not set, if the ignition key (50) is not in the “on” position, or if the hood (56) is open. Moreover, the system (10) is configured not to start if the fuel level is low, thus preventing an unintended depletion of fuel which could strand the vehicle and operator.

TECHNICAL FIELD

The present invention relates to an engine control system and more particularly to a method of automatically starting a combustion engine.

BACKGROUND OF THE DISCLOSURE

Combustion engines and particularly diesel engines have a wide variety of applications including passenger vehicles, marine vessels, earth-moving and construction equipment, stationary generators, and on-highway trucks, amongst others. Electronic engine controllers or electronic control modules, ECM, provide a wide range of capabilities which enhance engine operation, tailor engine performance to a particular application or operator, and reduce or eliminate undesirable characteristics typically associated with diesel engines, such as noise, smoke, or difficult starting. One feature which has been provided for various types of engines is the ability to automatically start and/or stop the engine based on various engine or ambient/environmental parameters.

For instance, in any of the above mentioned applications of diesel engines, automatic starting of the engine is desirable to preserve or maintain operating parameters necessary to later assure reliable starting of the engine when the operator intends to use the vehicle, equipment or truck. Automatic starting of the engine can recharge a battery with a depleting power supply, or will maintain engine oil and/or coolant temperatures above pre-established lower limits in cold weather which would otherwise prevent or hinder engine starts.

Moreover, truck owners seek to provide conveniences or amenities for the driver or operator because it is often difficult to attract and retain drivers in a competitive job market. For this application, automatic start/stop features are used to balance the fuel economy interests of the owner while providing conveniences to the driver, such as automatically starting and stopping the engine while the driver is parked to keep the cab temperature comfortable.

Prior to automatic starting of the engine, a series of interlocks or switches, which are monitored by the ECM, must be closed before the engine will start. These switches include a digital input park brake, a hood tilt switch, a transmission in neutral position switch, and a park brake switch. Unfortunately, amongst all of the known automatic engine start enablers, the engine will not be prevented from starting if the fuel level is low (i.e. below a predetermined level). Hence, automatic starting of the engine can run the vehicle or truck out of fuel, which would inadvertently leave the operator and vehicle stranded.

SUMMARY OF THE DISCLOSURE

In accordance with one aspect of the invention, an engine control system operates off a microprocessor of an engine control module, ECM, which will automatically start a combustion engine upon an enabler signal indicative of low battery voltage, high or low cab temperature and/or low engine temperature. The system also includes safety measures which will override the automatic starting of the engine. For instance, the vehicle will not automatically start if a vehicle speed is detected, if the parking brake is not set, if the ignition key is not in the “on” position, or if the hood is open. Moreover, the system is configured not to start if the fuel level is low (i.e. below a predetermined level), thus preventing an unintended depletion of fuel which could strand the vehicle and operator.

The ECM controls a series of fuel injectors and an engine starter motor for starting and stopping the engine at idle based upon a series of enabler inputs to the ECM which include a low battery voltage signal for ensuring minimum power is available to start the engine, a low engine temperature signal to ensure engine temperature does not drop so low that starting is difficult (a concern especially common for diesel engines) and a cab temperature range signal which will signal an engine start if the cab temperature wanders outside of a comfort range determined by the operator.

The overriding safety measures preferably entail a plurality of switches wired in series forming a grounded circuit which sends an input signal to the ECM. The fuel level feature is preferably a switch wired in series with the plurality of switches functioning as the overriding safety measures.

In accordance with another aspect of the invention, a method for automatically starting an internal combustion engine installed in a vehicle having an electronic engine control system in communication with a starter motor and a plurality of fuel injectors includes determining that one of three conditions exist, namely a voltage of a battery is below a predetermined limit, a temperature of the engine is below a predetermined limit, or a temperature of a cab of the vehicle is outside of a predetermined temperature range. The method also confirms that a hood is closed, that a transmission is in neutral, and that a park brake is set; and confirms that a fuel level is above a predetermined level. The engine is then started after the above conditions are met.

In accordance with another aspect of the invention, an engine control system for automatically starting and stopping a vehicle combustion engine at idle includes an engine control module for receiving inputs and providing an initiating output for starting and stopping the engine. An input is connected to the engine control for sending an initiating signal to the engine control module from a monitoring sensor to allow the engine control system to automatically start the engine. A first safety enabler circuit monitors a first set of parameters whereby each parameter is orientated with a respective grounded switch and opening of any one switch will open the circuit and disable the automatic start system preventing the engine control module from starting said engine and wherein one of the switches is orientated with a predetermined level of fuel in a fuel tank for said engine.

Objects, features and advantages of the present invention include an improved engine controller which prolongs engine life, reduces maintenance and assures reliable engine starts by monitoring outside conditions which would otherwise be adverse to the engine if not automatically started. Moreover, fuel economy is improved via the automatic shutting down of the engine when not needed, safety is enhanced via monitoring of various parameters which override automatic starting and stopping and inadvertent stranding of the operator and vehicle is prevented via incorporation of the fuel level input to the ECM.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 1, an engine control system10of the present invention automatically starts and stops a combustion engine12at idle. Preferably, the engine12is of a diesel type and utilized within large vehicle applications such as trucks or tractors14having an operator sleeping compartment16, a forward cab18and a semi-trailer20. The diesel engine12is installed in the truck14and interfaces with various sensors, switches, and actuators located on the engine12, cab18, and semi-trailer20. In other applications, the engine12may be used to operate industrial and construction equipment or in stationary applications for driving generators and/or pumps and the like.

The engine control system10will automatically stop and restart the engine12when required in order to keep the engine temperature above a specified value (such as sixty degrees Fahrenheit), a battery22charged, and/or the vehicle interior, sleeping compartment16or cab18in the desired temperature range. Benefits of the system include an overall reduction in exhaust emissions and noise, and improved starter and engine life via starting of a warm engine as oppose to a cold engine and operator comfort while sleeping in the sleeping compartment16.

Referring toFIG. 2, the engine control system10monitors various engine/vehicle conditions, as represented by block24, to determine if automatic starting of the engine12is permissible. Depending upon the particular application, the system10may include one or more event triggers which initiate an automatic engine start. For example, the current day/date and time as represented by block26may be used to automatically start the engine12. The automatic start may be programmed by the engine operator, a fleet owner/operator, or may be remotely programmed as described in Avery, U.S. Pat. No. 6,351,703, filed Jun. 6, 2000, incorporated herein by reference. Other events which may trigger an automatic engine start include various engine/vehicle temperatures such as oil temperature, fuel temperature, ambient temperature, and/or cab or coach temperature as represented by block28. Likewise, the voltage of battery22may be monitored to trigger an automatic start on low voltage as represented by block30. For applications utilizing an auxiliary pump, such as irrigation systems or fire truck applications and the like, pump pressure may trigger an automatic engine start as represented by block32. Various other engine/vehicle conditions may trigger an automatic engine start depending upon the particular application. Likewise, more than one condition may be required to trigger an automatic engine start.

Block34ofFIG. 2represents an enabler sequence which determines whether conditions are acceptable for automatically starting the engine12via the engine control system10. Engine/vehicle parameters which may be monitored include vehicle speed, parking brake status, ignition key position, hood switches, neutral gear and/or fuel level, as represented by respective blocks36,38,40,42,44and46.

In relation to blocks36and38, vehicle speed and/or the position of a parking brake or switch48(as best shown inFIG. 1) may be monitored to determine whether the vehicle/equipment is stationary prior to performing an automatic start. In other words, the parking brake48must be in a “set” position before automatic starting of the engine12. In relation to block40, an ignition key or switch50may be used as a master switch to initiate the automatic start sequence and to override or disable the engine control system10by turning the ignition key to the “off” position and/or removing the ignition key. Alternatively, the ignition switch50may be used for security reasons and another push button or switch52can be incorporated, in conjunction with the key switch50, to select automatic and/or manual starting of the engine12. That is, the ignition key50must be in an “on” position and the push button52must be in an “on” position before the engine control system10is enabled for automatically starting the engine12. In relation to block42, a hood switch54provides the indication that an engine hood56and/or compartment doors are closed thus preventing an automatic start while the engine12is being serviced, for example. With respect to block44, a transmission58of the engine12is monitored to assure that the transmission is in a neutral gear as indicated by switch60prior to an automatic start. This feature may also be used as a security measure to keep the transmission58in neutral and make it more difficult to move the vehicle/equipment without proper authorization. With respect to block46ofFIG. 2, a fuel level switch49, as best illustrated inFIGS. 1 and 3, will override an automatic engine start if the fuel level is below a predetermined level which can be pre-programmed as explained further.

Referring toFIGS. 1 and 3, an electronic control module, ECM62, of the engine control system10receives signals generated by the engine and vehicle sensors and processes the signals to control engine and/or vehicle actuators such as a plurality fuel injectors63necessary to automatically start and stop the engine12. The ECM62preferably includes computer-readable storage media for storing data representing instructions executable by a computer of the ECM62to control the engine12.

Referring toFIG. 3, the ECM62processes an ambient temperature analog input64of the cab18and/or sleeper compartment16from a programmable temperature controller66, a battery voltage input68monitored off the battery22, and an engine temperature input70; any one of which is a monitored engine/vehicle condition (as represented by block24ofFIG. 2) which can initiate the sequencing of an automatic engine start. For instance, if the cab18temperature is not within a prescribed comfort range, the engine12will automatically start to run heating and air conditioning system72. Likewise, if the battery voltage is below a prescribed value, the engine12will start to recharge the battery22and if the engine temperature drops below a prescribed value, the engine12will start to ensure reliable operation during extreme cold weather conditions.

To determine if automatic starting of the engine is permissible (as represented by block34ofFIG. 2), the ECM62also processes a digital first enabler input76which preferably is a grounded circuit having the hood switch54, the parking brake switch48and the neutral gear switch60orientated in series. Similarly, the ECM62processes a second enabler circuit or input78having the ignition switch50wired between a positive lead80of the battery22and the fuel level switch49wired in series between the ignition switch50and the ECM62. The circuit is completed and the input78provides a hot enable signal to the ECM62when both the ignition switch50is closed or in the “on” position and the fuel level switch49is closed indicating a sufficient amount of fuel in a fuel tank82of the truck14. The fuel level switch49is a float-type switch located within the fuel tank82. With both inputs76and78enabled, the ECM62will signal a starter relay83of an engine starter85to close via an output87.

Referring toFIG. 5, a second embodiment of an engine control system10′ illustrates a modified first enabler input or circuit76′ is illustrated. The circuit76′ includes a fuel level switch49′ wired in series to the hood switch54′, the neutral switch60′ and the parking brake switch48′. All of the switches54′,60′,48′ and49′ must be closed, thus grounding the circuit76′ before automatic starting of the engine12is enabled. Other methods of communicating the switch or circuit76′ status to the ECM62can be used. For instance, the ground can be replaced with a supply voltage and the logic or positioning (i.e. open or closed) of the switches reversed. Because automatic or unintentional and premature shutdown of the engine12is not typically desirable on low fuel level, the ignition or second enabler circuit78, as illustrated inFIG. 3, would require another circuit (not shown) wired in series across the fuel level switch49to prevent unintentional shutdown on low fuel level. For this reason, and when automatic shutdown on low fuel level is not desired, the embodiment illustrated inFIG. 5is more simplistic and thus preferable over that embodiment illustrated inFIG. 3.

Referring toFIG. 6, a third embodiment of an engine control system10″ illustrates a modified second enabler input or circuit78″. Circuit78″ is independent of the ignition switch50″ and directly inputs an enabler signal to the ECM62″ from a signal device49″ which measures fuel level. The device49″ can be an analog voltage sensor, a switch that triggers on a pre-set low fuel level which then sends a digital signal via circuit78″ to the ECM62″, or a data link device. The software utilized in the ECM62″ is modified from the software used in ECM62and ECM62′, thus enabling62″ to accept input from circuit78″ and enable processing of the enabler signal.

Referring toFIG. 3, the ECM62(and similarly for ECM62′ and ECM62″) also processes a series of shutdown enabler inputs which permit automatic shutdown of the engine12provided certain criteria are met. The shutdown enablers include a vehicle speed input84used as a safety measure preventing shutdown if the vehicle is moving. An engine speed input86requires that the engine12be at idle before shutdown is permitted. In addition, the engine temperature input70prevents automatic shutdown of the engine12if the engine temperature is below a prescribed value.

Depending upon the particular application, the engine control system10may include various types of sensors to monitor engine and vehicle operating conditions. For example, variable reluctance sensors may be used to monitor crankshaft position and/or engine speed. Variable capacitance sensors may be used to monitor various pressures such as barometric air, manifold, oil gallery, and optional pump pressures. Variable resistance sensors may be used to monitor positions such as a throttle (accelerator foot pedal) position. Magnetic pick-up sensors may be used to sense vehicle speed, accumulate trip distance, and for various other vehicle, features. Likewise, thermistors may be used to monitor various temperatures such as coolant, oil, and ambient air temperatures, for example. In one embodiment of the present invention, engine sensors include a timing reference sensor, TRS, which provides an indication of the crankshaft position and may be used to determine engine speed. An oil pressure sensor and oil temperature sensor are used to monitor the pressure and temperature of the engine oil, respectively.

Referring toFIGS. 4A–C, in order for the operator to utilize an automatic start feature of the engine control system10the master on/off switch52must be placed in the “on” position (represented by block90) and a series of conditions or safety features (represented by block92) must be met and are thus continuously monitored by the ECM62when the system is initiated. For instance, the ignition switch50must be in the “on” position with the engine12idling, the hood56or any other compartment doors must be closed, the transmission58must be in neutral, and the park brake48must be “set.” With these conditions met, and regardless of which position the master on/off switch52is in, a programmable idle shutdown timer94integral to the software of the ECM62, as shown inFIG. 3, is enabled and begins a countdown of a prescribed time, of for instance approximately five minutes (represented by block96). With the countdown started and with the master on/off switch52in the “on” position, an active indicator light or alarm100will begin flashing indicating the automatic start feature is active, thus the engine12will automatically restart when needed after the countdown expires and the engine12automatically shuts down (represented by block102).

Assuming the automatic start master on/off switch52was not previously placed in the “on” position and the countdown of the timer94has already begun, the system10will allow the switch52to be turned “on” within a prescribed lapse of time during the countdown (represented by diamond104). For instance, the operator can move the switch to “on” within the first 3.5 minutes of the five minute countdown which will activate the flashing of light100, as best shown by block105. Although not illustrated, the engine control system10will allow operation of all electronic control features while the active light100is flashing.

If the master on/off switch52is not timely placed in the “on” position, the indicator light100will not flash and countdown of the timer94will eventually expire thus automatically shutting down the engine12without the ability to automatically re-start, as best represented by block107ofFIG. 4A.

The engine12will shutdown via the idle shutdown timer if any one of the following two conditions occur; the engine12has been idling for a specified time period, or the engine12has been idling for a specified time period and the ambient temperature is within a specified range. In order for the idle shutdown timer of the ECM62to automatically shutdown the engine12, the following conditions must be met for the entire time-out period; the engine temperature remains above a present value such as one hundred and four degrees Fahrenheit, the engine operation is at idle or at a minimum variable speed governor, VSG, the parking brake interlock digital input remains switched to battery ground, the OEM supplied interlocks remain enabled, and the ignition switch50remains in the “on” position.

When the engine12is shutdown by the idle shutdown timer94, fueling to a series of injectors63of the engine12is stopped by the ECM62, however, the ignition switch50or circuit remains active. For manual start of the engine12by the driver, the ignition switch50must be cycled to the “off” position to deactivate the idle shutdown timer94, and the driver must wait for a pre-determined time such as ten seconds before the driver can cycle the ignition switch50back to the “on” position to manually start the engine12. The CEL or indicator light100will blink to indicate when the engine has shutdown via the idle timer94.

With the automatic starting feature activated, the countdown expired, and the engine12automatically shutdown, the active indicator light100will stop flashing and illuminate solid/steadily (represented by block106). At this point, the operator will no longer be able to use other electronic control features including the electronic throttle108(seeFIG. 1) until the park brake48is released, one of the safety conditions are broken (block92), or the master on/off switch52is turned “off.”

With the engine12shutdown and the active indicator light100illuminated steadily, the engine control system10will monitor various vehicle and engine parameters to determine if an automatic start of the engine12is desirable (see battery voltage input68, thermostat input64and engine temperature input70ofFIG. 3; and block109ofFIG. 4B). These parameters are divided into two modes of operation being an “engine mode” and a “thermostat mode.” With the engine control system10active, the engine will either shutdown if control parameters are satisfied, or ramp to a pre-established engine speed such as 1100 rpm.

When the engine idle control system is in the “engine mode,” the engine12will automatically start when the battery voltage drops below a pre-set level, for example below 12.2 volts of a twelve volt system or 24.4 volts for a twenty-four volt system. Once started by a signal of the low voltage input68, the engine12will run for a pre-set time period, such as twenty minutes to two hours depending upon the type of engine or application. Also, when in the “engine mode,” the engine12will automatically start when the engine temperature input70signals the oil or engine temperature has dropped below a pre-set temperature such as sixty degrees Fahrenheit and will automatically shutdown when the oil temperature reaches one hundred and four degrees Fahrenheit.

The “thermostat mode” of the automatic engine control system10is advantageous to truck owners seeking to provide conveniences or amenities for the driver or operator because it is often difficult to attract and retain drivers in a competitive job market. In this mode, automatic engine start/stop features are used to balance the fuel economy interests of the owner while providing conveniences to the driver, such as automatically starting and stopping the engine12while the driver is parked to keep the cab18or sleeper compartment16temperature comfortable. Likewise, after the engine12has been idling at a specified period of time, or after the engine12has been idling at a pre-set period of time and the ambient temperature is within a specified range, the automatic engine idle control system10via the idle shutdown timer94will automatically shut down the engine12, as previously described.

When the engine control system10is in the “thermostat mode,” the thermostat controller66must be turned “on” which causes “engine mode” parameters as well as the interior cab temperature to be monitored. The thermostat controller66informs the ECM62via the thermostat input signal64of when to start/stop the engine12to keep the interior temperature within a specified range sensed by a termistor101and based on a thermostat setting entered by the operator into the thermostat controller66, as best shown inFIG. 3. When in the “thermostat mode,” the system10also monitors the outside or ambient temperature by way of a skin temperature sensor or thermistor103to determine if the ambient external temperature is extreme enough that the engine12should be run continuously.

Referring toFIG. 3, when in the “thermostat mode,” any vehicle accessories connected to a vehicle power shutdown relay110will turn on for “thermostat mode” engine starts. In contrast, a heater fan112and an air conditioning fan114of the conditioning system72will remain off for the “engine mode” starts. Moreover, if the engine12is started on “engine mode,” and the operator then requests the “thermostat mode,” the heater and air conditioning fans112,114of the conditioning system72will turn on after a pre-set delay, such as thirty seconds from when the “thermostat mode” is selected.

Automatic engine starting operation of the engine control system10requires that the ignition switch50is left in the “on” position. When active, the indicator light100within the cab18is illuminated (see block106). The ECM62is then capable of determining when the engine12needs to start to charge the battery22, warm the engine12or heat/cool the cab18or sleeper compartment16(see block109). Just prior to starting, an audio alarm116will sound briefly (see block111) via a pulse width modulated signal from an output117of the ECM62. The starter motor85of the engine12will then engage and the engine12will start (see block113).

If the engine12does not start, the engine control system10will attempt a second engine start after a preset delay time, such as approximately forty-five seconds (see block115). The alarm116will sound a second time just prior to the second start attempt. If the engine12does not start after the second attempt, the system10will disarm for the rest of the ignition cycle, or that time in which the ignition switch50remains in the “on” position (see block118). If the engine12does start, the engine will ramp up to a pre-established speed, such as approximately 1100 RPM. And, if the engine was started in the thermostat mode, the heater fan112or the air conditioning fan114will turn on after a pre-set time delay, such as approximately thirty seconds.

It is also foreseen that instead of switch49, the engine control module may have an analog input from a fuel tank gauge and be pre-programmed with a fuel amount which if sensed below the pre-programmed level will prevent automatic starting of the engine.

It is also foreseen that the pre-programmed level may be adjustable by using a global positioning device, determining the location of the motor vehicle and determining with preloaded memory or an input signal the location and mileage from the nearest fuel station in or along the direction which the vehicle will head. In this way the fuel level parameter may be more individually categorized to the particular situation for the vehicle.