Systems and method for a cold start system for a gaseous fuel engine

Apparatuses, methods, and systems for starting an internal combustion engine under cold start conditions are disclosed. A combustible mixture is supplied to a plurality of cylinders of the internal combustion engine, where a number of ignition devices are operably connected with less than all of the plurality of cylinders so that at least one of the plurality of cylinders does not include an ignition device. In one form, only one ignition device is included in a bank of cylinders. In response to a cold start condition, a spark by the plurality of ignition devices is generated to cause ignition of the combustible mixture and start the internal combustion engine. In response to a normal or non-cold starting condition, the internal combustion engine is started by compression ignition where none of the ignition devices generate a spark.

TECHNICAL FIELD

This disclosure relates generally to internal combustion engines, and more particularly is concerned with a cold start system for a gaseous fuel type internal combustion engines.

BACKGROUND

Gaseous fuel engines often encounter difficulties during cold start and low temperature conditions. When the engine is cold, the walls of the pre-combustion or combustion chambers are cold and act as a heat sink and impair the combustion characteristics of the engine, leading to poor starting performance.

To overcome the cold start and low temperature conditions, a spark plug is typically provided in every cylinder of the engine to ignite the fuel in these conditions. However, during warmed up or normal start conditions or normal temperature conditions, the engine does not require the use of the spark plugs to ignite the fuel. Therefore, the spark plugs are not utilized during the normal start conditions. As can be appreciated, engines are often started under normal conditions than cold start conditions. However, the spark plugs must still be provided for possible cold start conditions which add to the cost and complexity of the engine. Thus, there remains a need for additional improvements in systems and methods for cold start conditions.

SUMMARY

There is disclosed an internal combustion engine system that includes an engine having a plurality of cylinders and a number of ignition devices, wherein the number of ignition devices is assembled with the plurality of cylinders such that less than all of the plurality of cylinders include at least one of the number of ignition devices in operable association therewith to ignite a fuel in the associated cylinder. Also disclosed is a technique to supply a combustible mixture to a plurality of cylinders of an internal combustion engine, wherein a number of ignition devices are operably connected with less than all of the plurality of cylinders so that at least one of the plurality of cylinders does not include an ignition device, generating a spark by the plurality of ignition devices to cause ignition of the combustible mixture in response to a cold start condition, and starting the internal combustion engine. Also disclosed is a technique of starting an internal combustion engine that includes evaluating a starting condition of the internal combustion engine with a control system of the internal combustion engine, wherein the internal combustion engine has a plurality of cylinders and a number of ignition devices, wherein the number of ignition devices is assembled with the plurality of cylinders such that less than all of the plurality of cylinders include at least one of the number of ignition devices in operable association therewith, in response to determining a cold start starting condition, generating a spark with the number of ignition devices to start the internal combustion engine, and in response to determining the cold start condition does not exist, starting the internal combustion engine by compression ignition. The technique includes less than half of the plurality of cylinders including one of the number of ignition devices in operable association therewith and the normal start condition does not include generating any spark with the number of ignition devices.

This summary is provided to introduce a selection of concepts that are further described below in the illustrative embodiments. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

DETAILED DESCRIPTION

With reference toFIG. 1, an internal combustion engine system20is illustrated in schematic form. In certain forms, internal combustion engine system20is a single-fuel engine system such as a spark ignited engine structured to combust gaseous hydrocarbon fuel. Examples of gaseous hydrocarbon fuels (sometimes referred to herein generally as gas) include a variety of types of natural gas and other gaseous hydrocarbons, for example, pipeline gas, wellhead gas, producer gas, field gas, nominally treated field gas, well gas, nominally treated well gas, bio-gas, methane, ethane, propane, butane, liquefied natural gas (LNG), compressed natural gas, landfill gas, condensate, or coal-bed methane (CBM). In such forms, fueling system22is operable with internal combustion engine system20to provide fueling for engine30from a first fuel source102which provides a supply of gaseous fuel for combustion by compression ignition by internal combustion engine system20. In such forms fuel source102is the sole fuel source and may be configured so that the fuel is pre-mixed with the charge flow upstream of the combustion chambers of engine cylinders. In certain forms, internal combustion system20is structured as a micro pilot fuel engine system, for example an engine structured to combust main gaseous fuel by spark ignition for starting purposes under cold start conditions, and combust main gaseous fuel by igniting ‘liquid fuel by compression ignition’ after starting of the engine. In such forms, fueling system22includes a second fuel source104for providing a liquid fuel such as diesel fuel, other liquid fuels, or lubrication oil for combustion by internal combustion engine system20.

Internal combustion engine system20includes engine30connected with an intake system24for providing a charge flow to engine30and an exhaust system26for output of exhaust gases in an exhaust flow. The engine30is provided as a spark ignited gas engine for ignition of a liquid fuel adapted to combust a gaseous fuel flow by compression ignition. The gaseous fuel can be, for example, any of the aforementioned types. In certain embodiments, engine30uses a liquid fuel in second fuel source104such as diesel fuel for micro pilot injection and act as a source for ignition of a gaseous fuel in first fuel source102such as natural gas. Again, the gaseous fuel can be any of the aforementioned types. In the illustrated embodiment, the engine30includes six cylinders34a-34fin a first cylinder bank36aand six cylinders34g-34lin a second cylinder bank36barrangement. However, the number of cylinders (collectively and individually referred to as cylinder(s)34) may be any number, and the arrangement of cylinders34unless noted otherwise may be any arrangement including an in-line arrangement, and is not limited to the number and arrangement shown inFIG. 1.

Engine30includes an engine block32that at least partially defines the cylinders34. A plurality of pistons (not illustrated) may be slidably disposed within respective cylinders34to reciprocate between a top-dead-center position and a bottom-dead-center position while rotating a crankshaft (not illustrated). Each of the cylinders34, its respective piston, and the cylinder head form a main combustion chamber (not illustrated). In the illustrated embodiment, engine30includes twelve such main combustion chambers. However, it is contemplated that engine30may include a greater or lesser number of cylinders34and main combustion chambers and that cylinders34and main combustion chambers may be disposed in an “in-line” configuration, a “V” configuration, or in any other suitable configuration. In some forms, each of the cylinders34includes a prechamber that is in fluid communication with the main combustion chamber.

In the embodiment illustrated inFIG. 1, less than all of the cylinders34include an ignition device35. The ignition devices35can be operably disposed with the main combustion chamber or the prechamber of the cylinders34. InFIG. 1, cylinders34b,34d,34f,34h,34j, and34linclude the corresponding ignition devices35b,35d,35f,35h,35j, and35l, respectively. Ignition devices35b,35d,35f,35h,35j, and35lare in operable association to ignite fuel from the first fuel source102and/or the second fuel source104. As can be appreciated, a greater number of cylinders34can include corresponding ignition devices35. The ignition devices35a-35lcan be a spark plug, a diesel pilot ignition device, a plasma ignition device, a laser ignition device, a thermal ignition device, or a non-thermal ignition device.

In other embodiments, a fewer number of cylinders34can include corresponding ignition devices35. For example, inFIG. 2, ignition device35ais associated with cylinder34ain the first cylinder bank36aand ignition device35gis associated with cylinder34gin the second cylinder bank36b. InFIG. 2, the remaining cylinders34b-34fand34h-34ldo not have ignition devices associated with them therefore there is only one ignition device that being35aassociated with the first cylinder bank36aand one ignition device that being35gassociated with the second cylinder bank36b. The ignition devices35can be arranged in different cylinders34in each of the cylinder banks36aand36b. For example, in one form, ignition device35bcan be associated with cylinder34band ignition device35hcan be associated with cylinder34hand the remaining cylinders34do not include any ignition devices35. There may be other arrangements or configurations of the ignition devices35.

In yet another arrangement inFIG. 3, ignition devices35a,35dare associated with cylinders34a,34d, respectively, in the first cylinder bank36aand ignition devices35g,35iare associated with cylinders34g,34iin the second cylinder bank36b. InFIG. 3, the remaining cylinders34b,34c,34e,34fand34h,34j-34ldo not have ignition devices associated with them. As such, there are two ignition devices associated with the first cylinder bank36aand two ignition devices associated with the second cylinder bank36b. In other forms, the ignition devices35can be arranged in a different configuration in each of the cylinder banks36aand36b.

In yet another arrangement inFIG. 4, ignition devices35a,35d,35fare associated with cylinders34a,34d,34f, respectively, in the first cylinder bank36aand ignition devices35g,35i,35l, are associated with cylinders34g,34i,34l, respectively, in the second cylinder bank36b. InFIG. 4, the remaining cylinders34b,34c,34e, and34h,34j,34kdo not have ignition devices associated with them. As such, there are three ignition devices associated with the first cylinder bank36aand three ignition devices associated with the second cylinder bank36b. In other forms, the ignition devices35can be arranged in a different configuration in each of the cylinder banks36aand36b.

Moreover, in any embodiment, the number of ignition devices35in the first cylinder bank36amay be the same as the number of ignition devices35in the second cylinder bank36b. Alternatively, the number of ignition devices35in the first cylinder bank36amay be less than or greater than the number of ignition devices35in the second cylinder bank36b. There may be one or more cylinders34that do not have any ignition devices35associated with them positioned adjacent one of cylinders34that do have one of ignition devices35associated with it.

In one embodiment, engine30is a four stroke engine. That is, for each complete engine combustion cycle (i.e., for every two full crankshaft rotations), each piston of each cylinder34moves through an intake stroke, a compression stroke, a combustion or power stroke, and an exhaust stroke. Thus, during each complete combustion cycle for the depicted twelve-cylinder engine, there are twelve strokes during which air is drawn into individual combustion chambers from intake system24and twelve strokes during which exhaust gas is supplied to an exhaust manifold (not illustrated).

The engine30includes cylinders34connected to the intake system24to receive a charge flow and connected to exhaust system26to release exhaust gases produced by combustion of the primary and/or secondary fuels. Exhaust system26may provide exhaust gases to a turbocharger (not illustrated), although a turbocharger is not required. In still other embodiments, multiple turbochargers are included to provide high pressure and low pressure turbocharging stages that compress the intake flow.

Furthermore, exhaust system26can be connected to intake system24with one or both of a high pressure exhaust gas recirculation (EGR) system (not illustrated) and a low pressure EGR system (not illustrated). These EGR systems may each include a cooler and a bypass. In other embodiments, one or both of EGR systems are not provided. When provided, EGR system(s) provide exhaust gas recirculation to engine30in certain operating conditions. In any EGR arrangement during at least certain operating conditions, at least a portion of the exhaust output of cylinder(s)34is recirculated to the engine intake system24.

Fuel system22may provide either fueling from a single fuel source or, in other embodiments, micro pilot fueling of engine30from second fuel source104in addition to main fueling from first fuel source102. In one micro pilot fuel embodiment, fuel system22includes first fuel source102connected to intake system24with a mixer or connection50at or adjacent an inlet of a compressor (not illustrated). First fuel source102is configured to provide a flow of gaseous fuel to cylinders34. Second fuel source104is connected to each of the cylinders34such as through respective ones of the direct injectors38a-38l, and second fuel source104is configured to provide a flow of liquid fuel to cylinders34with one or more direct injectors38a-38lat or near each of the cylinders34such as from a common rail. In the micro pilot fueling, less than 1% of the total fuel, wherein the total fuel includes fuel from the first fuel source102and fuel from the second fuel source104, is from the second fuel source104. In the illustrated embodiment, the cylinders34each include at least one direct injector38a-38lfor delivering fuel to the combustion chamber thereof from a liquid fuel source, such as first fuel source102, but multiple direct injectors and/or port injectors are also possible.

A direct injector, as utilized herein, includes any fuel injection device that injects fuel directly into the cylinder volume (combustion chamber), and is capable of delivering fuel into the cylinder volume when the intake valve(s) and exhaust valve(s) are closed. The direct injector may be structured to inject fuel at the top of the cylinder or laterally of the cylinder. In certain embodiments, the direct injector may be structured to inject fuel into a combustion pre-chamber.

In the micro pilot fuel embodiments where the first fuel source102is a gaseous fuel and the second fuel source104is a liquid fuel, a control system including controller100is configured to control the flow of gaseous fuel from first fuel source102and the flow of liquid fuel from second fuel source104in accordance with engine speed, engine loads, intake manifold pressures, and fuel pressures, for example. A control system including controller100is configured to control the flow of gaseous fuel from first fuel source102in accordance with engine speed, engine loads, intake manifold pressures, and fuel pressures, for example, and provide a pilot injection of liquid fuel from second fuel source104. The first fuel source102is independent of the second fuel source104, and the controller100is configured to control the flow of gaseous fuel from the first fuel source102independently of the flow of liquid fuel from the second fuel source104.

Ignition devices35are electrically connected with controller100to receive spark or firing commands that provide a spark in the respective cylinder34in accordance with a cold start condition as determined by the controller100. If a cold start condition does not exist, then the ignition devices35will not receive any spark or firing commands.

Controller100can be connected to actuators, switches, or other devices associated with a first shutoff valve62operably connected to the first fuel source102, a second shutoff valve64operably connected to the second fuel source104, fuel pumps, ignition devices35, and/or injectors38and configured to provide control commands thereto that regulate the amount, timing and duration of the flows of the gaseous and/or liquid fuels to cylinders34, charge flow (if present), and exhaust flow (if present) to provide the desired operating conditions, cold start conditions, and normal start conditions.

As discussed above, the positioning of each of actuators, switches, or other devices associated with first and second shutoff valves62and64, respectively, ignition devices35, and/or injectors38can be controlled via control commands from controller100. In certain embodiments of the systems disclosed herein, controller100is structured to perform certain operations to control generating a spark with the ignition devices35in cold start conditions, and the controller100is structured to perform certain operations to start the engine system20by compression ignition when the cold start condition does not exist.

In certain embodiments, the controller100forms a portion of a processing subsystem including one or more computing devices having memory, processing, and communication hardware. The controller100may be a single device or a distributed device, and the functions of the controller100may be performed by hardware or software. The controller100may be included within, partially included within, or completely separated from an engine controller (not shown). The controller100is in communication with any sensor or actuator throughout the systems disclosed herein, including through direct communication, communication over a datalink, and/or through communication with other controllers or portions of the processing subsystem that provide sensor and/or actuator information to the controller100.

The controller100includes stored data values, constants, and functions, as well as operating instructions stored on computer readable medium. Any of the operations of exemplary procedures described herein may be performed at least partially by the controller100. Other groupings that execute similar overall operations are understood within the scope of the present application. Modules may be implemented in hardware and/or on one or more computer readable media, and modules may be distributed across various hardware or computer implemented. More specific descriptions of certain embodiments of controller operations are discussed herein below.

Controller100may be structured to implement a cold start condition which shall now be further described. Cold start conditions can be determined in a variety of ways, and different criteria can be employed to make such a determination. For example, a temperature representative of air intake temperature can be employed to determine cold start conditions. Such a temperature can be ambient air temperature, controller temperature or actual air intake temperature. When the temperature representative of air intake temperature is below a first temperature threshold then cold start conditions exist. The temperature of the charge in the combustion chamber at the end of the compression stroke decreases as the air intake temperature decreases. Gaseous fuel temperature, liquid fuel temperature, and/or pilot fuel temperature can be monitored to determine if any of these temperatures is below a respective temperature threshold to assess a cold start condition.

Alternatively or additionally, engine oil temperature can be employed to determine cold start conditions. When the engine oil temperature is below an engine oil temperature threshold then cold start conditions exist. The viscosity of engine oil increases as its temperature decreases. During cold start conditions due to engine oil viscosity it takes significantly more battery power to crank the engine and as a result the crank speed decreases as engine oil temperature decreases.

Other temperatures can be employed to determine cold start conditions. Engine coolant temperature can be an indication of whether the engine has been recently running, thereby providing an indirect measure of engine oil temperature. When engine coolant temperature is below an engine coolant temperature threshold then cold start conditions exist. Generally speaking, engine oil temperature mostly varies with engine output, whereas engine coolant temperature varies with engine output, airflow and radiator capacity. As a result, engine oil temperature is largely unrelated to engine coolant temperature, except that when the oil temperature is warm it is likely that the coolant temperature is warm.

Controller temperature inputs can be employed to determine whether the engine was previously running, in which case controller temperature will be higher than ambient air temperature. Battery temperature can also be monitored to determine cold start conditions. When battery temperature is below a battery temperature threshold then cold start conditions exist. Battery internal resistance increases as temperature decreases, which decreases output voltage and battery capacity, thereby reducing battery power available for cranking the engine. In very cold operating environments, for example, the electrolyte in lead acid batteries has the danger of freezing so external heat sources may be employed to heat the battery, reducing the effectiveness of battery temperature alone as an indication of cold start.

Any one or combination of ambient air temperature, air intake temperature, battery temperature, engine coolant temperature, engine oil temperature, gaseous fuel temperature, liquid fuel temperature, and pilot fuel temperature being below a respective temperature threshold, within a certain temperature range, or meeting certain criteria can be used to determine whether a cold start condition exists.

With reference toFIG. 5there is illustrated exemplary control process500which may be implemented in an electronic controller such as controller100. Control process500is suitable for use in internal combustion engine system20. Control process500includes a number of control blocks and inputs which are examples of control operators which may be used in performing their respective functions which shall now be further described.

Control process500is initiated at supply block502which provides or supplies a combustible mixture to the cylinders34of the internal combustion engine system20. The combustible mixture includes the first fuel source102and the second fuel source104as described previously. The control process500proceeds to cold start condition block504to determine if one or more of the cold start conditions described above are present. If the cold start condition from block504exists, then the control process500proceeds to spark block506which operates the ignition devices35to generate a spark. The control process500then proceeds to ignition block508and ignites the combustible mixture in the cylinders34. If the cold start condition block504determines that none of the cold start conditions are present, then the process500proceeds to ignition block508. Therefore, there are two techniques to ignite the combustible mixture in cylinders34. If the cold start condition exists from block504, then the combustible mixture is ignited with the spark from the ignition devices35that are provided in less than all of the cylinders34. If the cold start condition does not exist from block504, then the combustible mixture in all of the cylinders34is ignited by compression ignition. The control process500then proceeds to start block510that starts the engine30.

Various aspects of the present disclosure are contemplated. According to one aspect, a system, comprising an internal combustion engine having a plurality of cylinders and a number of ignition devices, wherein the number of ignition devices is assembled with the plurality of cylinders such that less than all of the plurality of cylinders include at least one of the number of ignition devices in operable association therewith to ignite a fuel in the associated cylinder.

In one embodiment the system includes the plurality of cylinders including a first bank of cylinders and a second bank of cylinders, wherein the number of the ignition devices is arranged such that no more than half of the first bank of cylinders and no more than half of the second bank of cylinders include the ignition devices in operable association therewith.

In one embodiment the system includes the number of ignition devices is operably associated with less than half of the plurality of cylinders in an alternating sequence. In a further embodiment the system includes the alternating sequence includes a first cylinder that does not have one of the number of ignition devices in operable association with the first cylinder adjacent to a second cylinder that has one of the ignition devices in operable association with the second cylinder. In yet another embodiment the system includes the alternating sequence includes two or more cylinders that do not have the ignition devices in operable association therewith positioned near one cylinder that has one of the ignition devices in operable association with the one cylinder.

In one embodiment the system includes each of the less than all of the plurality of cylinders includes a main combustion chamber, and the number of ignition devices are operably disposed at least partially within the main combustion chambers.

In one embodiment the system includes each of the less than all of the plurality of cylinders includes a prechamber in fluid communication with a main combustion chamber, and the number of ignition devices are operably disposed within the prechambers.

In one embodiment the system includes the internal combustion engine includes a controller configured to control ignition of the number of ignition devices in response to a cold start condition of the internal combustion engine. In a further embodiment the system includes the controller is configured to determine the cold start condition in response to at least one of ambient air temperature, air intake temperature, battery temperature, controller temperature, engine coolant temperature, engine oil temperature, liquid fuel temperature, and gaseous fuel temperature being below a respective temperature threshold.

In one embodiment the system includes the internal combustion engine includes a fuel system having a first fuel source operable to provide a liquid fuel to the plurality of cylinders and a second fuel source operable to provide a gaseous fuel to the plurality of cylinders. In a further embodiment the system includes the liquid fuel is diesel fuel and the gaseous fuel is selected from the group consisting of natural gas, bio-gas, methane, propane, ethanol, producer gas, field gas, liquefied natural gas, compressed natural gas, or landfill gas. In a further embodiment the system includes the internal combustion engine includes a plurality of fuel injectors assembled with the plurality of cylinders, the plurality of fuel injectors configured to deliver at least the liquid fuel to the plurality of cylinders.

According to another aspect a method comprises supplying a combustible mixture to a plurality of cylinders of an internal combustion engine, wherein a number of ignition devices are operably connected with less than all of the plurality of cylinders so that at least one of the plurality of cylinders does not include an ignition device; generating a spark by the plurality of ignition devices to cause ignition of the combustible mixture in response to a cold start condition; and starting the internal combustion engine.

In one embodiment, the method includes one of the number of ignition devices is operably connected with every alternate one of the plurality of cylinders.

In one embodiment, the method includes only one of the number of ignition devices is operably connected with a corresponding one the plurality of cylinders.

In one embodiment, the method further includes controlling with a controller of the internal combustion engine the generating a spark by the plurality of ignition devices. In a further embodiment the method includes the cold start condition is determined in response to at least one of ambient air temperature, air intake temperature, battery temperature, controller temperature, engine coolant temperature, engine oil temperature, liquid fuel temperature, and gaseous fuel temperature being below a respective temperature threshold.

In one embodiment, the method includes the plurality of cylinders includes a first bank of cylinders and a second bank of cylinders, wherein the number of the ignition devices is arranged such that no more than half of the first bank of cylinders or half of the second bank of cylinders include the ignition devices in operable connection therewith.

Another aspect includes a method of starting an internal combustion engine comprises evaluating a starting condition of the internal combustion engine with a control system of the internal combustion engine, wherein the internal combustion engine has a plurality of cylinders and a number of ignition devices, wherein the number of ignition devices is assembled with the plurality of cylinders such that less than all of the plurality of cylinders include at least one of the number of ignition devices in operable association therewith; in response to determining a cold start starting condition, generating a spark with the number of ignition devices to start the internal combustion engine; and in response to determining the cold start condition does not exist, starting the internal combustion engine by compression ignition.

In one embodiment, the method includes less than half of the plurality of cylinders includes one of the number of ignition devices in operable association therewith and the normal start condition does not include generating any spark with the number of ignition devices.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only certain exemplary embodiments have been shown and described. Those skilled in the art will appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.

In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.