AND METHOD FOR DIESEL ENGINES

FIELD OF THE INVENTION

[0001] This invention relates to a method and apparatus for improving the fuel economy, power, and torque provided by diesel engines, and for reducing their emissions of particulates and oxides of nitrogen (NOx). The invention further relates to a method and apparatus for injecting a secondary fuel including an alcohol into the intake manifold of a diesel internal combustion engine.

BACKGROUND

[0002] Fuel prices are rapidly increasing as the world's supply of fossil fuels is constrained as demand increases. The need to find improved fuel economy for the transport of goods and services is essential to the ongoing success of society. Regulations are now in place that demand substantial improvement in fuel economy for engines used for a wide variety of applications including commercial transportation, agriculture, off-road, and power generation to name but a few. The vehicles that have these engines installed are kept in service for a substantial length of time, often in excess of 20 years. Replacing the engines to comply with these new regulations or to improve fuel economy can be expensive. Similarly, replacing the entire vehicle can be expensive. Due to the substantial time that these vehicles are kept in service and the high costs of replacement described above, a simple, cost effective retrofit solution that provides fuel economy and emissions benefits for existing vehicles is highly desirable as a viable alternative to having to rapidly replace existing vehicles or engines short of their useful life with newer more fuel-efficient vehicles or engines.

SUMMARY OF THE INVENTION

[0003] A secondary fueling system is provided for the introduction of a secondary fuel such as an alcohol-based fuel into the combustion intake system of a diesel internal combustion engine. The system includes a fuel tank for containing the secondary fuel, a secondary fuel pump for withdrawing secondary fuel from the fuel tank, a regulator receiving the secondary fuel from the secondary fuel pump and supplying the secondary fuel to an injection system, a secondary controller for operating the secondary fuel pump, the regulator, and the injection system for introducing metered amounts of secondary fuel into the combustion intake system. The injection system includes a fuel injector controlled by the controller for regulating the secondary fuel using pulse width modulation control. [0004] In another aspect of the invention, the above system is provided and introduces the secondary fuel to the diesel combustion engine by performing the steps of: connecting the secondary controller to a main engine controller of the diesel combustion engine; activating the secondary fuel pump and the regulator; receiving information from the main engine controller relating to engine operation parameters; evaluating the received engine operation parameters using control steps and stored data carried by the secondary controller; determining an amount of secondary fuel to introduce into the diesel combustion engine; providing a control signal correspond to the determined amount of the secondary fuel to the fuel injector; and introducing the secondary fuel into the vehicle intake manifold hose via the secondary fuel pump, the regulator, and the fuel injector.

[0005] One aspect of the present invention is providing a source of a secondary fuel which may be alcohol-based for a diesel engine, which is introduced into the combustion air intake system just prior to the intake manifold and cylinders forming an atomized air/fuel mixture for introduction into the cylinders. Once the air/secondary fuel mixture flows into the cylinder, the atomized air/fuel mixture mixes with the injected diesel fuel and forms a co- fueled mixture that provides enhanced combustion of the diesel fuel. The slower burning alcohol allows for a more homogeneous burn of the diesel fuel in the engine combustion chamber. By burning more completely, there is more of the useable energy from the diesel fuel charge extracted in each combustion cycle. A more complete burn process delivers fewer undesirable the emission gases.

[0006] In another aspect of the invention, a secondary control system is utilized to communicate with the existing control system of the engine to provide a measured amount of atomized fuel into the combustion chambers via the air intake according to p re-determined ratios.

[0007] In another aspect of the invention, a sensor can be located in the combustion exhaust stream that is in communication with the secondary control system and this sensor provides information to allow a precise amount of secondary atomized fuel to be injected just prior to the combustion chambers in the air intake system.

[0008] In another aspect of the invention, a sensor is located on the engine that is in communication with the secondary computer that senses engine temperature and provides an injection of atomized alcohol into the combustion chambers through the intake manifold to assist with cold starting of the vehicle.

BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a schematic of the system that provides the fuel and control system for injecting secondary fuel into a fuel injection system of a diesel engine; [0010] Figure 2 is a pictorial view of an intake adapter for adapting an existing vehicle engine combustion air intake system to incorporate the features of the present invention; and

[0011] Figure 3 is a schematic view of an adapter mounted to an exhaust system of a diesel engine for injecting secondary fuel into the exhaust stream for performing selective catalytic reduction.

DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS

[0012] This invention is directed towards improving the fuel economy of a diesel engine 108 utilizing the addition of alcohol (or other fuel) as a secondary fuel. A system 100 is shown schematically in Figure 1 that can provide improved fuel economy along with other benefits.

[0013] The system 100 is preferably designed to be a retro-fit solution to existing vehicle engines and sensors, where the system 100 complements and modifies particular engine attributes, further described below. The system 100 includes a secondary fuel tank 101 that is used by the system 100 in addition to the primary diesel fuel tank of the vehicle. The secondary fuel tank 101 is configured to hold secondary fuel, such as alcohol or alcohol/gasoline mixtures like E85 ethanol. E85 is a label for an ethanol fuel blend of 85% denatured ethanol fuel and 15% gasoline or other hydrocarbon by volume, although the exact ratio of fuel ethanol to hydrocarbon can vary considerably while still carrying the E85 label. The ethanol content can be adjusted according to the local climate to maximize engine performance. Another type of secondary fuel includes a water/alcohol emulsion. In one form, the emulsion preferably can include between approximately 50-100% alcohol. In one approach, 60-70% alcohol can be used. In another approach, 50% alcohol can be used. It will be appreciated that other amounts of alcohol between 50% and 100% could be used, as well. Other possible secondary fuel mixtures include gasoline, water, and alcohol.

[0014] The system 100 further includes a sending unit 102 that measures the level of secondary fuel within the tank 101. The fuel level measured by the sending unit 102 is sent to an ECOIS (ECO Injection System) secondary controller 104 for the purpose of monitoring the secondary fuel level to assure safe operation.

[0015] The ECOIS secondary controller 104 is a further component of the system

100 and is preferably configured for communicating with a main engine controller 106 of the existing vehicle via an OBD (on-board diagnostic) port, such as a J1939 OBD port. Thus, the ECOIS controller 104 can send information to the main controller 106, as well receive information from the main controller 106. [0016] The system 100 also includes a fuel pump 1 12 for pumping the secondary fuel from the secondary tank 101 ultimately to the engine 108.

[0017] The system 100 also includes a secondary fuel gauge 105. The gauge 105 is preferably configured for being mounted within the vehicle cabin. The gauge 105 receives an output signal from the controller 106, which receives the fuel level from the sender 102. The secondary fuel gauge 105 thereby indicates to the driver of the vehicle the amount of secondary fuel remaining in the secondary tank 101.

[0018] The system 100 is typically powered by a main relay 103, which is preferably

12V DC (but could go to higher voltages which may be used in future vehicles). The controller 104 is powered through relay 103. The controller 104 can in turn power its various connected components. The power is typically supplied upon starting the engine of the vehicle, but could also be supplied in response to powering the vehicle before engine start, and can continue to be powered after engine shut-off.

[0019] The system further includes a fuel regulator 1 1 1 and a secondary fuel pump

1 12. The secondary fuel pump 1 12 is in addition to the main fuel pump of the vehicle (not shown) and is electrically connected and controlled by the controller 104. The secondary fuel pump 1 12 can be powered by the relay 103. The system further includes a fuel filter 1 13 and a fuel return line 1 14. The return line 1 14 includes a one way (check) valve 1 14a.

[0020] The secondary fuel is delivered via an injection system 107 that includes a fuel injector 120 (Fig. 2). When the system 100 determines that secondary fuel should be delivered to the engine 108, the pump 1 12 will be activated by the controller 104 and will cause the secondary fuel to flow from the tank 101 , through the filter 1 13 and the pump 1 12 and into the regulator 1 1 1. The secondary fuel will continue through the regulator 11 1 and flow into the injection system 107 for injection into the engine 108.

[0021] The system 100 also can include an exhaust sensor 1 15 for measuring vehicle exhaust levels. The exhaust sensor 1 15 can be an existing vehicle sensor that is connected to the main controller 106 or it can be an additional sensor that is connected to the ECOIS controller 104. However, the system 100 can operate without the use of the exhaust sensor 1 15, if desired.

[0022] Generally, the secondary fuel pump 1 12 supplies secondary fuel on a constant basis through the fuel filter 1 13, then through the pressure regulator 1 1 1 , which is a manifold compensated secondary fuel pressure regulator, and then back to the tank 101 through a return line 114. The regulator 1 1 1 supplies a constant pressure of secondary fuel to the fuel injection system 107 which includes the fuel injector 120 (shown in Fig. 2).

[0023] The pressure of the secondary fuel is adjusted via an intake manifold pressure feedback signal 109. This assures that there is a constant pressure differential across the manifold injection system 107 over a range of manifold pressures (which can vary from vacuum conditions to boosted pressure e.g. from turbocharging or supercharging, depending on the load and operating conditions) so that the mass flow rate of secondary fuel supplied is accurately controlled by the ECOIS controller 104 which controls the operation of injector 120 preferably via pulse width modulation (PWM) control. For example, the intake manifold pressure can be detected, and the fuel pump pressure can be adjusted relative to the intake manifold pressure to ensure that the pressure difference between them remains constant.

[0024] When power to vehicle is activated, the controller 104, being connected to the main controller 106 via an OBD port, communicates with the existing engine controller 106 and receives numerous engine operating signals, including one or more of engine rpm, load, % torque, throttle position, engine coolant temperature, engine faults, mass air flow, net fuel flow, mass fuel flow, brake application, engine idle, road speed, gear position, and other vehicle parameters that may be determined by various known sensors and other parameter detecting mechanisms. The controller 104 can receive at least a portion of the above parameters as inputs and thereby control the system 100, and particularly the fuel pump 1 12 and injection system 107.

[0025] Connected to the fuel pressure regulator 1 1 1 is a secondary fuel pressure sensor 1 10. This sensor 1 10 is connected directly to the ECOIS controller 104 and continuously monitors secondary fuel pressure to assure correct and safe operation of the system. For example, if the secondary fuel pressure in the regulator 1 1 1 is determined to be too high, the pressure can be relieved through the return line 1 14 to the tank 101. Once the correct parameters are met, the ECOIS controller 104 activates the injection system 107 to supply the correct amount of secondary fuel into the engine based on a predetermined open loop or a specific closed loop calibration derived in part from signals sent by the exhaust sensor 1 15, which is ultimately communicating with the ECOIS controller 104.

[0026] In order to operate the system at its peak efficiency, the ECOIS controller 104 monitors engine and vehicle parameters including one or more of engine temperature, rpm, throttle position, net fuel flow, mass air flow, brake application, engine % torque, and the like, and then uses an ECOIS algorithm and calibration to decide the amount of secondary fuel to atomize into the intake system 107. As part of this system, the ECOIS controller 104 may additionally monitor fuel pressure, fuel level, engine fault codes, and/or engine temperature to assure correct and safe operation of the system. The system 100 will not engage to introduce the secondary fuel unless all of the necessary operational and safety conditions are met. [0027] In order to operate the system at its peak efficiency, the ECOIS controller 104 monitors engine operation continuously and continuously varies the amount of alcohol (or other secondary fuel) from 0% to 20% (compared with mass flow rate of diesel-primary fuel) that it injects and is atomized into the intake system 107. This is done to optimize the fuel economy and to reduce the regulated emissions from the engine.

[0028] The algorithm implemented by the ECOIS controller 104 can potentially use various primary parameters for control, for example:

a) Mass air flow through the engine;

b) Mass fuel flow through the engine, which includes the secondary fuel; or

c) Net diesel fuel flow, which does not include the secondary fuel.

[0029] The system 100 goes through a logic sequence to determine if the system 100 will operate. The logic system may, for example, be essentially based on engine temperature, fuel level, fuel pressure, brake pedal position, gear position, vehicle speed, and other inputs. It is preferable for the control algorithm to make it as precise as possible through the feedback system from the manifold pressure to the pressure regulator 1 1 1. The system 100 adjusts the fuel pressure in direct proportion to the pressure in the manifold. As mentioned above, this provides a constant pressure drop across the injector 107 and as such does not require active adaption of the control. This approach simplifies control in that mass flow rate of the introduced secondary fuel is directly proportional to the PWM duty cycle, over a range of various intake manifold pressures.

[0030] In one approach, the software carried on controller 104 goes through a number of steps:

a) Decide if safety conditions are met, which include engine operation, fuel pressure, fuel level, gear position, brake switch, and vehicle speed;

b) Retrieve a number of parameters for initial calculation, including one or more of engine speed, throttle position, vehicle speed, and engine torque; c) Using either fuel flow or mass air flow, modifying the flow by the stored constant in the calibration table and then by the fuel flow calibration from the particular injector used;

d) Computing the amount of fuel to be injected and outputting this amount as a signal to the fuel injector.

[0031] The control algorithm takes a calibration point from a table that could include

RPM, MAP, RPM, or other parameters. The inventors have found that there is a direct correlation between emission performance and calibration, especially total hydrocarbons (THC), particulates, and oxides of nitrogen. Of these, THC is the most indicative of calibration since oversupply of the secondary fuel results in unburned hydrocarbons detected in the exhaust gases. One approach is to provide a closed loop system that monitors THC and feeds this back into the control system for constant calibration. This will allow one controller to be used essentially for all engines, and allow the system to learn as it goes and adjust for fuel used, engine age, etc.

[0032] Another approach is to provide a closed loop system that monitors oxygen content and feeds this back into the control system for constant calibration. This will allow one controller to be used essentially for all engines, and allow the system to learn as it goes and adjust for fuel used, engine age, etc.

[0033] In another approach, the controller 104 is capable of being used essentially for all engines by basing the amount of metered secondary fuel on the fuel flow rate of the engine 108. This can be determined by measuring the mass airflow into the engine 108 via existing airflow sensors or via an optional secondary mass air flow sensor 121 , further described below. The secondary mass air flow sensor 121 , if used, can be connected to the controller 104 and the mass airflow can be determined based on the sensor output. In the event of using an existing mass airflow sensor, this sensor is ultimately connected to the main controller 106, and the ECOIS controller 104 can obtain the air flow data via its connection to the main controller 106. In a similar approach, the diesel fuel flow rate can be detected by a fuel flow sensor (not shown), and this reading can be used to calibrate the injection of secondary fuel. The mass air flow and diesel fuel flow generally correspond to each other via a predetermined ratio, so determining the level of one inherently provides the level of the other.

[0034] With reference to Figure 2, the fuel injector 120 of the injection system 107 is shown in further detail. As previously described above, the injection system 107 is in communication with the controller 104 and is activated based on the control algorithms for injecting secondary fuel into the engine 108. For example, the controller 104 can receive various vehicle data regarding the operation of the engine and, based on this received data, can determine the appropriate amount of secondary fuel to introduce. The injection system 107 includes an intake adapter 122. The intake adaptor 122 is located close to the intake valves, preferably as close as possible. The construction of the intake adapter 122 maintains adequate mixing of the atomized alcohol (or other secondary fuel) into the airstream.

[0035] The injection system 107 shown in Figure 2 is shown in the form of an installable adaptor sleeve that contains all of the needed elements to correctly operate the ECOIS system 100. This includes the intake adapter 122, which is a hollow elongated sleeve configured to be installed between existing vehicle intake manifold hoses 123 and 124. The intake adapter 122 includes a port 125 that is in fluid communication with the inside of the sleeve and provides for the installation of the secondary fuel injector 120. The intake adapter 122 can also include a port 127 for installation of the secondary mass air flow sensor 121 , if used, and can further include a manifold air pressure port 126. The system 100, however, can operate without the mass air flow sensor 121 , if desired.

[0036] In one approach, the intake adapter 122 is installed into the existing vehicle's intake system as close as possible to the engine's intake valves. In another approach, an existing intake system or manifold can be modified to accommodate the above-described components necessary for correct operation of the ECOIS system. For example, the ports 125, 126, and 127 could be added to the existing vehicle intake manifold hose without the use of the intake adapter 122. The intake adapter 122, however, provides for a relatively easy retrofit of existing systems, where it can be installed in-line with the existing vehicle intake manifold hose near the vehicle intake manifold.

[0037] In addition to the capabilities of improving engine operating fuel efficiency, the systems and methods of the present invention may provide other advantageous attributes. For example, using alcohol as a secondary fuel may assist in cold start and warm up and hence reducing overall emissions, due to the increased emissions that generally exist with cold start and warmup.

[0038] Presently, diesel engines built after 2010 often have a NOx catalyst that uses urea as a reductant. This is commonly referred to as Selective Catalytic Reduction ("SCR") and is used to control or reduce NOx emissions from diesel engines. The urea is part of a liquid solution and commonly referred to as diesel exhaust fluid ("DEF"). In the near term, systems will be released that use a different catalyst that is cheaper and will be using E85 as the reductant. As such, diesel powered trucks will soon begin to carry E85 on the vehicle instead of DEF and E85 will thereby become more available at commercial truck refueling centers.

[0039] The system 100 can be adapted to control and supply the E85 or alcohol emulsion for SCR and replace the DEF based system. This could be accomplished in at least two ways. In one approach, the reductant is introduced by direct injection of some of the secondary fuel into the exhaust manifold. In this approach, the secondary fuel is introduced before the combustion chamber (as described above with respect to the injection system 107) and also after the combustion chamber (as the reductant).

[0040] In another approach, the reductant is introduced by over-fueling the engine with secondary fuel in the intake system by the injection system 107 and having the excess alcohol carry through into the exhaust stream. It also has another very beneficial impact in that the system will produce less particulates (PM) and NOx at the source, and the load on these secondary devices for emission reduction is lessened and as such they will last much longer, or could be smaller and cheaper and will use less alcohol as the reductant fluid.

[0041] An example of the system 100 being adapted to introduce the secondary fuel after the combustion is shown in Figure 3. As shown in Figure 3, an injection system 207 having an output adapter 222 is installed after the engine for supplying secondary fuel to the exhaust stream. The output adapter 222 can have a sleeve shape with a fuel injector 220 extending therefrom. The fuel injector 220 receives fuel from the regulator 1 1 1 and is controlled by the controller 104 based on detected vehicle parameters. The amount of fuel to be injected into the exhaust stream can be metered using pulse width modulation, so the various flow rates and pressure drops do not need to be adjusted from the operating conditions of the remainder of the system 100.

[0042] In the overfueling approach, the controller 104 can be adapted to simply supply more fuel than it would without the SCR functionality.

[0043] In another approach, the secondary fuel tank 101 can be fitted to supply the injector system 107 as described above, and further adapted to supply fuel to other alcohol based SCR systems that currently exist.

[0044] The system 100 can also be adapted to respond to the driving conditions and driving habits of the vehicle operator. For example, when throttle position or movement indicates that an off-throttle condition is expected, such as when the operator decreases throttle activation, the system 100 can cut-off supply of secondary fuel. This can conserve secondary fuel for later use.

[0045] The system 100 can also be adapted to detect an engine runaway condition of the diesel engine. Such a condition is generally rare, but can damage a diesel engine. In response to detecting such a condition, the system 100 can cease injecting the secondary fuel into the engine 108.

[0046] While the above description constitutes the preferred embodiment of the present invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the accompanying claims.