A method of converting a diesel engine to a natural gas engine comprising inserting a spark plug into a diesel fuel injector opening in a cylinder head; installing a throttle body on the diesel engine; installing a throttle body adaptor between a throttle body and an intake manifold of said diesel engine; and modifying a piston, whereby the compression ratio of said piston is decreased during operation of said piston. The method also includes installation of a waste gate and waste gate adaptor and a timing mask.
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1. A method of converting a diesel engine to a natural gas engine characterized by, the diesel engine having an intake manifold, a cylinder head having one or more injector openings which receive for receiving a fuel injector, and one or more pistons in corresponding cylinders, said method comprising:
removing said fuel injectors from said injector openings;
inserting a spark plug into each of said injector openings;
installing a throttle body adaptor on said intake manifold, the adapter being structured to accommodate connection of a throttle body to the intake manifold of the diesel engine;
installing a throttle body on said adaptor, said throttle body having a throttle plate which responds to actuation of an accelerator pedal and opens to allow more air/fuel air into the intake manifold;
modifying said pistons to decrease the compression ratio in said cylinders during operation of said engine; and
modifying providing said pistons to have with one of a three-ring or four-ring piston assembly;
providing at least one ring that is structured to expand into sealing engagement with the cylinder wall during the intake stroke of the piston to resist passage of oil into the combustion chamber during the intake stroke of the piston when the throttle plate is closed;
and wherein said throttle body adaptor further comprises a flange and a hose, said hose engaging said flange and engaging said intake manifold.
2. A method of converting a diesel engine having no waste gate to a natural gas engine characterized by, the diesel engine having an intake manifold, a cylinder head having one or more injector openings which receive for receiving a fuel injector, and one or more pistons in corresponding cylinders, said method comprising:
removing said fuel injectors from said injector openings;
inserting a spark plug into each of said injector openings;
installing a throttle body adaptor on said intake manifold, the adapter being structured to accommodate connection of a throttle body to the intake manifold of the diesel engine;
installing a throttle body on said adaptor, said throttle body having a throttle plate which responds for responding to actuation of an accelerator pedal by opening to allow more air/fuel air and fuel into the intake manifold;
modifying said pistons to decrease the compression ratio in said cylinders during operation of said engine; and
modifying providing said pistons to have with one of a three-ring or four-ring piston assembly;
providing at least one ring that is structured to expand into sealing engagement with the cylinder wall during the intake stroke of the piston to resist passage of oil into the combustion chamber during the intake stroke of the piston when the throttle plate is closed; and
installing a waste gate and a waste gate adaptor on said diesel engine, said waste gate adaptor enabling a turbocharger to communicate with an exhaust manifold on said engine through said adaptor; wherein, said waste gate adaptor has having an orifice for connection to said waste gate and also has having holes aligned with the exhaust manifold and turbocharger.
0. 3. The method of claim 1, further comprising, installing a waste gate and a waste gate adaptor on said diesel engine, said waste gate adaptor enabling a turbocharger to communicate with an exhaust manifold on said engine through said adaptor, said waste gate adaptor having an orifice for connection to said waste gate and also having holes aligned with the exhaust manifold and turbocharger.
0. 4. The method of claim 1, wherein the step of inserting a spark plug into each of said injector openings includes providing a sleeve within each of said injector openings, each sleeve containing said spark plug.
0. 5. The method of claim 4, further comprising securing each sleeve to an upper interior portion of each of said injector openings.
0. 6. The method of claim 5, further comprising:
providing threads within said upper interior portion of each of said injector openings: and
providing threads on an upper portion of each sleeve, said threads on said upper portion of each sleeve being structured to engage said threads within the upper interior portion of each of said injector openings.
0. 7. The method of claim 4, further comprising securing each sleeve to an interior bottom portion of each of said injector openings.
0. 8. The method of claim 7, further comprising:
providing threads within said interior bottom portion of each of said injector openings: and
providing threads on a lower portion of each sleeve, said threads on said lower portion of each sleeve being structured to engage the threads within said interior bottom portion of each of said injector openings.
0. 9. The method of claim 1, further comprising:
providing an idle air control on said throttle body;
providing an air control orifice on said throttle body adapter; and
connecting said air control orifice to an idle air control.
0. 10. The method of claim 1, further comprising:
providing a throttle position sensor on said throttle body; and
utilizing the throttle position sensor to provide a throttle plate position to an electronic control unit.
0. 11. The method of claim 1, wherein the step of modifying one of said pistons and said cylinders to decrease the compression ratio in said cylinders during operation of said engine includes removing material from a top of said piston.
0. 12. The method of claim 11, further comprising forming a concave portion within said top of said piston.
0. 13. The method of claim 1, wherein the step of modifying said pistons to have one of a three-ring and a four-ring piston assembly includes providing a scraper ring, an oil ring, and at least one central reverse torque ring disposed between said scraper ring and said oil ring.
0. 14. The method of claim 13, wherein said at least one central reverse torque ring is provided in an orientation wherein said at least one central reverse torque ring is structured to expand towards a cylinder wall during an intake stroke of said piston.
0. 15. The method of claim 1, further comprising:
securing a timing mask to a timing gear of said engine; and
providing a sensor, said sensor being structured to detect rotation of said timing mask.
0. 16. The method of claim 15, wherein the step of providing a sensor includes providing a hall-effect timing pick-up.
0. 17. The method of claim 2, wherein the throttle body adaptor further comprises a at least one of the configurations including:
an adapter body having a central orifice, a plurality of first apertures structured to permit securing the throttle body adapter to the intake manifold, a plurality of second apertures structured to permit securing the throttle body adapter to the throttle, and an air control orifice; or
an adapter body that is structured to be secured to the throttle, the adapter body having a flange that is connected to a hose, the hose being structured to be secured to the intake manifold.
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This application is a continuation in part application of Ser. No. 10/274,672, filed Oct. 21, 2002 now U.S. Pat. No. 6,910,269 which is a continuation-in-part application of (1) U.S. Provisional Application Ser. No. 60/343,853 filed on Oct. 19, 2001 entitled “Method and System for Modifying a Diesel Engine to Run on Natural Gas: Head Modification Patent”; (2) U.S. Provisional Application Ser. No. 60/343,933 filed on Oct. 19, 2001 entitled “Method and System for Modifying a Diesel Engine to Run on Natural Gas: Piston Configuration and Ring Placement Patent”; (3) U.S. Provisional Application Ser. No. 60/343,925 filed on Oct. 19, 2001 entitled “Method and System for Modifying a Diesel Engine to Run on Natural Gas: Waste Gate Adaptor and Exhaust Patent”; (4) U.S. Provisional Application Ser. No. 60/343,931 filed on Oct. 19, 2001 entitled “Method and System for Modifying a Diesel Engine to Run on Natural Gas: Throttle Body Adaptor Patent”; and (5) U.S. Provisional Application Ser. No. 60/343,930 filed on Oct. 19, 2001 entitled “Method and System for Modifying a Diesel Engine to Run on Natural Gas: Timing Mask and Timing Pick Up Patent,” all of which are hereby incorporated herein by reference.
Not Applicable.
The present invention is directed to converting diesel engines to spark ignited natural gas fueled engines.
The conversion of diesel engines into natural gas operation has been an aspiration of the internal combustion engine industry for a period of time. Natural gas, which includes LPG, CNG, LNG, and hydrogen, is a clean burning fuel (relative to diesel) with improved emission levels of both nitrogen oxides (NOx) and particulate matter. Thus, increasing concern over exhaust emissions regulation and fuel efficiency have led to an interest in burning a combustible gaseous mixture, such as propane or natural gas in diesel engines, particularly in diesel engines used in road HD trucks, stationary, marine, and locomotive applications. Thus, a method of converting diesel engines to spark ignited engines that will meet Environmental Protection Agency (“EPA”) and California Air Resources Board (“CARB”) ultra low emission standards is desired.
A number of strategies have been used for the conversion of diesel engines to spark ignited natural gas engines. Such conversions have included replacing the diesel fuel injectors with spark plugs connected to a suitable ignition system and providing a throttle body on the intake manifold. See Friddell, U.S. Pat. No. Re. 26,145. Another method involves changing the camshaft lobes to change intake and exhaust opening timings so that the compression ratio does not need to be changed. See Chen, U.S. Pat. No. 5,315,981. Another conversion method involves utilizing a rocker and fulcrum mechanism to open the exhaust valves of the engine to degrease the reflux of exhaust gasses into the combustion chamber. See Bennett, U.S. Pat. No. 4,911,124. However, none of these methods has been fully satisfactory in the conversion process.
Those skilled in the art will recognize that the steps needed to convert a diesel engine to an engine utilizing natural gas will depend on the specific type of diesel engine. For example, while a spark plug assembly must be inserted in all diesel engines for conversion, those skilled in the art will recognize that because some diesel engines are manufactured with waste gates, a waste gate adaptor will not be required for conversion. Likewise, because many diesel engines are manufactured with a timing mask, installation of such a device will not be required. For illustrative purposes, the present invention is described with reference to the Navistar 466 Engine (also known as the “old generation” or “legend” engine) and the Navistar 530 and 466E Engines (also known as the “new generation” engines). Thus, the present invention is not intended to be limited to conversion of the specific diesel engines described herein.
A. Spark Plug Assembly
To convert a four-stroke diesel engine to a spark-ignited natural gas engine, the first step involves modifying the cylinder head to accept spark plugs. It will be appreciated by those skilled in the art that in some diesel engines, this modification may involve removing the diesel fuel injector. In other engines, this step may require machining of the diesel injector hole and threading the hole to accept the spark plug. Yet, in other cases, a sleeve for encasing the spark plug may be machined in order to prohibit water from reaching either the spark plug or the piston cylinder.
As illustrated in
The top of the cylinder head (100) shown in
As discussed above, in
Due to the extreme heat generated by the burning of natural gas, the intake and exhaust valves, as well as the valve seats, are preferably cryogenically treated such that they are frozen below minus 250° F., and more preferably below minus 350° F. This processes hardens the valves and seats, increasing their ability to withstand heat.
B. Throttle Body Adaptor
In a natural gas engine, a throttle body regulates the flow of air from the atmosphere to an intake manifold that provides an air/fuel mixture to engine combustion chambers. Providing maximum airflow to the combustion chamber enables the engine to reach maximum power. The engine produces a minimum amount of power when airflow is almost entirely restricted, such as when the engine is idling. Of course, airflow must be regulated by the throttle body between maximum and minimum engine power so that the engine may perform under a variety of vehicle operating conditions.
The present invention is intended to utilized with all of the various throttle bodies are known to those skilled in the art. An example of such a throttle body (200) that can be used in accordance with the present invention is that from a GM Chevrolet 454 engine. As discussed above, the throttle body (200) introduces both air and fuel into the intake manifold (210) and the intake valves (not shown). This is accomplished on the intake stroke of the piston when the intake valves are open for the piston in the correct firing order (not shown). The throttle body performs several functions. First, the throttle body is fitted with an idle air control (“IAC”) (202) to allow for smooth idle and cold start performance. Second, the throttle body has a throttle position sensor (“TPS”) (204) which tells an electronic control unit the position of the throttle plate or butterfly. The throttle plate, which responds to actuation of the accelerator pedal, determines the amount of air/fuel required to run the engine at the desired speed. In general, when the throttle plate is horizontal, it closes the air/fuel mixture, and when opened, the throttle plate becomes increasingly more vertical to allow more air/fuel into the intake manifold to increase speed and power.
In accordance with the present invention, a throttle body adaptor (220) is utilized in order to accommodate placement of a throttle body (200) on the engine. Examples of such throttle body adaptors (220) are shown in
As illustrated in
In an alternative embodiment, as shown in
C. Piston Configuration and Ring Placement
To convert a four-stroke diesel engine to a spark-ignited natural gas engine, the third step involves modifying the piston configuration and ring placement. The closing of the throttle plate creates a tremendous amount of vacuum pressure in the cylinders, which in turn, places a heavy demand on the piston rings to keep oil from escaping past the rings in the piston cylinder. In the event that this oil is not contained, the engine will burn the oil and create large amounts of particulate matter, smoke, and unwanted emissions.
Those skilled in the art also recognize that a the diesel ring set is designed to accommodate the very high compression ratios required to accomplish compression ignition, compressing the air/fuel in the cylinder until is causes combustion. Because a diesel engine never creates a vacuum, the diesel ring set is designed to expand out towards the cylinder wall on the compression stroke and to relax on the intake stroke. The present invention utilizes a ring set which allows the conversion of a diesel engine to natural gas.
In accordance with the present invention, a four-ring piston is utilized to accomplish the conversion and prevent unwanted emissions. In one embodiment, as illustrated in
In another embodiment, a three-ring piston set may be utilized for some engines. The piston utilizes a top scraper ring, only one middle reverse torque ring, and a bottom three-piece oil ring. Such ring assemblies are suitable for Hastings or Federal Mogul pistons.
As discussed above, the diesel compression ratio is typically large, on the order of about 16:1 to 22:1. In order to convert a diesel engine to a natural gas burning engine, the ratio is lowered to about 9:1 to 12:1, and preferably between 10:1 to 11:1 and even more preferably to 10.5:1. As illustrated in
Those skilled in the art will recognize that varying amounts of material may need to be removed to obtain the desired compression ratio depending on the type of engine. Likewise, the exact amount of material will depend on the bore and stroke of the particular engine being converted. In addition, the location of the concave portion may vary. As illustrated in the Navistar new generation 466E engine in
D. Waste Gate Adaptor
Another aspect of the present invention's method of converting a diesel engine to a natural gas engine involves installation of a waste gate in front of the turbocharger. While many modern diesel engines are equipped with a waste gate, many older models do not have such a device. A turbocharger consists of a turbine which drives a compressor to charge or force more air into the engine's inlet manifold. The turbine is driven by exhaust gases from the exhaust manifold. The waste gate controls the amount of boost, or compressed air, from the turbocharger into the throttle body and into the intake manifold and individual inlet passages of the cylinder head to the intake valves. In general, the waste gate limits the boost in a turbocharger via a valve. The waste gate bypasses the exhaust under certain conditions. Without a waste gate, a turbocharger will destroy an engine by over boosting the intake charge.
An example of a diesel engine which has no waste gate is the Navistar 466 engine. As illustrated in
As shown in
E. Timing Mask
The present invention also involves modification of the camshaft gear to accommodate a timing mask in some diesel engines. While many modern diesel engines are equipped with a timing mask, many older models do not have such a device. For example, while the Navistar 466E new generation engine has a timing mask, the Navistar 466 old generation engine is not equipped with a timing mask.
As illustrated in
A hole (535) is also drilled in the front plate (532) of the engine block (530). An adaptor (540) is positioned inside a hole on the front plate. The adaptor (540) is comprised of a non-metallic metal and is fitted into hole via a hold-down bracket (548) which is in turn secured by a bolt that is threaded through threaded hole in the front plate. The bracket (548) is U-shaped bracket and straddles the adaptor. Preferably, the bracket is comprised of steel. Due to a machined ridge on the outside of the adaptor, the bracket (548) holds the adaptor (540) in place in the front plate when the attaching bolt is tightened. The adaptor (540) receives a hall effect timing pick-up (545) well known to those skilled in the art which is connected to an electronic control unit (not shown) which monitors and controls the timing.
The timing mask (510) can be modified to fit the timing gear (500) utilized by the particular diesel engine that is being converted to a natural gas engine. An example of a timing mask (510) that can be utilized in conjunction with the Navistar 466 engine is shown in
While specific embodiments have been shown and discussed, various modifications may of course be made, and the invention is not limited to the specific forms or arrangement of parts and steps described herein, except insofar as such limitations are included in the following claims. Further, it will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of the claims.
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