DIESEL TO NATURAL GAS CONVERSION SYSTEM

Abstract

A dual-fuel conversion system that introduces natural gas into at least one engine cylinder and replaces diesel fuel with a replacement pilot fuel for ignition. The system includes replacement injectors that mount to an injector adapter that replaces the original diesel fuel injector, a control computer that is reprogrammed to control timing of the replacement injectors, and replacement fuel components to distribute natural gas and a pilot fuel to the at least one engine cylinder.

Claims

1. A method for using a pilot fuel other than diesel to initiate combustion in a diesel engine converted to use natural gas, the method comprising: monitoring, by a computer system, natural gas temperature near or at one or more injectors; controlling, by the computer system, timing of ignition of the natural gas that is triggered using the pilot fuel; and determining, by the computer system, an improvement in control of injector timing and amount of natural gas that is introduced to a cylinder based on the monitoring of natural gas temperature.

2. The method of claim 1 further comprising: monitoring natural gas flow near or at the one or more injectors; and determining an improvement in control of the injector timing and amount of natural gas that is introduced to the cylinder based on the monitoring of natural gas flow.

3. The method of claim 1 wherein the diesel engine includes an addition of one or more openings to allow insertion of the one or more injectors.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0024] Advantages of embodiments of the present invention will be apparent from the following detailed description of the exemplary embodiments thereof, which description should be considered in conjunction with the accompanying drawings in which like numerals indicate like elements, in which:

[0025] FIG. 1 is an exemplary embodiment of an existing diesel fuel injection system.

[0026] FIG. 2 is an exemplary embodiment of a diesel fuel injection system having the glow plug removed.

[0027] FIG. 3 is an exemplary embodiment of a diesel fuel injection system that has been converted to a natural gas/pilot fuel system.

[0028] FIG. 4 is an exemplary embodiment of an existing diesel fuel injection system and cylinder head.

[0029] FIG. 5 is an exemplary embodiment of a diesel fuel injection system and cylinder head that has been converted to a natural gas/pilot fuel system.

[0030] FIG. 6 is an exemplary embodiment of a system diagram for an existing diesel fuel injection system.

[0031] FIG. 7 is an exemplary embodiment of a system diagram for a diesel fuel injection system that has been converted to a natural gas/pilot fuel system.

DETAILED DESCRIPTION

[0032] Aspects of the invention are disclosed in the following description and related drawings directed to specific embodiments of the invention. Alternate embodiments may be devised without departing from the spirit or the scope of the invention. Additionally, well-known elements of exemplary embodiments of the invention will not be described in detail or will be omitted so as not to obscure the relevant details of the invention. Further, to facilitate an understanding of the description discussion of several terms used herein follows.

[0033] As used herein, the word exemplary means serving as an example, instance or illustration. The embodiments described herein are not limiting, but rather are exemplary only. It should be understood that the described embodiments are not necessarily to be construed as preferred or advantageous over other embodiments. Moreover, the terms embodiments of the invention, embodiments or invention do not require that all embodiments of the invention include the discussed feature, advantage or mode of operation.

[0034] Further, many embodiments are described in terms of sequences of actions to be performed by, for example, elements of a computing device. It will be recognized that various actions described herein can be performed by specific circuits (e.g., application specific integrated circuits (ASICs)), by program instructions being executed by one or more processors, or by a combination of both. Additionally, the sequence of actions described herein can be considered to be embodied entirely within any form of computer readable storage medium having stored therein a corresponding set of computer instructions that upon execution would cause an associated processor to perform the functionality described herein. Thus, the various aspects of the invention may be embodied in a number of different forms, all of which have been contemplated to be within the scope of the claimed subject matter. In addition, for each of the embodiments described herein, the corresponding form of any such embodiments may be described herein as, for example, logic configured to perform the described action.

[0035] According to an exemplary embodiment, and referring generally to the Figures, various exemplary implementations of a conversion system for converting a diesel engine to a pilot-fuel-fired natural gas engine may be disclosed.

[0036] Turning now to exemplary FIG. 1, FIG. 1 displays an exemplary embodiment of an existing diesel fuel injection system 100. According to an exemplary embodiment, a diesel fuel injection system 100 may include a groove in the cylinder head, a, in which the various other components of the diesel fuel injection system 100 may be disposed; a lug, b, used to secure the prechamber 5; a nozzle holder 1; a threaded ring 2 disposed around the top of the prechamber 5; a seal ring 3 disposed between the prechamber 5 and the cylinder head; a seal ring 4 disposed between the prechamber 5 and the nozzle holder 1; a prechamber 5, which in this case may be a ball pin prechamber 5; a ball pin 6 disposed in the prechamber 5; and a glow plug 7.

[0037] Turning now to exemplary FIG. 2, FIG. 2 displays an exemplary embodiment of a diesel fuel injection system 200 having a glow plug 7 removed and FIG. 1 prechamber 5 removed and replaced with an adapter/pre-combustion insert 206. The insert 208 shape will be configured to direct fuel flow dispersion for optimal distribution and combustion. In an exemplary embodiment, a glow plug 7 or the prechamber 5 may be removed during a conversion process.

[0038] Turning now to exemplary FIG. 3, FIG. 3 displays an exemplary embodiment of a diesel fuel injection system 300 that has been converted to a natural gas/pilot fuel system. According to an exemplary embodiment, a prechamber 5 may be removed and replaced by an adapter/pre-combustion insert and a first fuel injector may be replaced by a natural gas-specific fuel injector. In a next step, a glow plug 7 may be replaced by a second fuel injector 302 which may, like the first fuel injector, face downward into the adapter/pre-combustion insert. In an exemplary embodiment, an adapter may first be installed in the glow plug 7 hole in order to better retain the second fuel injector 302 in the glow plug 7 hole. In another exemplary embodiment, a second fuel injector 302 may be approximately the same size as a glow plug 7 (for example, a second fuel injector 302 may be engine-specific or may be shaped to replace a particular glow plug 7 or set of glow plugs 7) and may be installed into the glow plug 7 hole without the use of an adapter, such as may be desired.

[0039] Very large engines, such as marine engines, may benefit from an addition of more than one hole for the addition of multiple new injectors. Another embodiment may include removing the diesel fuel injectors and replacing each with first an injector adapter, into which an injector may be installed. In some cases, the injector may not need an adapter.

[0040] In an exemplary embodiment, the first and the second fuel injector 302 may be coupled to a natural gas source and a small pilot fuel tank. For example, according to an exemplary embodiment, the second fuel injector 302 (which may be the pilot fuel injector) may be coupled to a small pilot fuel tank and the first fuel injector (which may be the natural gas fuel injector) may be coupled to a natural gas source, such as may be desired.

[0041] Turning next to exemplary FIG. 4, FIG. 4 displays an exemplary embodiment of an existing diesel fuel injection system 400 and cylinder head such as might be found in existing diesel engines. According to an exemplary embodiment, an exemplary embodiment of an existing diesel fuel injection system 400 and cylinder head 402 may have a fuel injector 404, may have an O-ring 406 spaced around the fuel injector 404, may have a nozzle nut 408 used to secure the fuel injector 404 in place, may have a prechamber 410 disposed at the distal end of the fuel injector 404, and may have a piston 412 designed to operate within the cylinder and extend upwards toward the cylinder head 402. In an exemplary embodiment, the piston 412 may have a top clearance 414 that is equal to the piston deck height plus the thickness of the compressed head gasket 416.

[0042] Turning next to exemplary FIG. 5, FIG. 5 displays an exemplary embodiment of a diesel fuel injection system 500 and cylinder head 502 that has been converted to a natural gas/pilot fuel system. According to an exemplary embodiment, a cylinder head 502 may be replaced with a cylinder head 502 specifically intended to be used with two fuel injectors; in another exemplary embodiment, a cylinder head 502 may be modified in order to accept two fuel injectors, for example by a user tapping into the cylinder head 502 in order to install the second fuel injector into the cylinder head 502.

[0043] For example, according to an exemplary embodiment, a first fuel injector 504 may be installed and may be coupled to a natural gas source, and a second fuel injector 506 may be installed and coupled to a pilot fuel tank. In some exemplary embodiments, the order may be reversed such that the first fuel injector 504 is coupled to a pilot fuel tank and such that the second fuel injector 506 is coupled to a natural gas source, if desired. According to an exemplary embodiment, the first and the second fuel injector 504, 506 may each have an O-ring 508, 510, may each have a nozzle nut 512, 514, and may each have an adapter/pre-combustion insert 516, 518 installed at the distal end of each respective fuel injector 504, 506. The combustion chamber may further have a piston 520 which may extend almost all of the way up to the cylinder head 502 when fully extended; as before, the top clearance of the piston 520 may be equal to the piston deck height plus the thickness of the compressed head gasket 522.

[0044] The timing and duration of the pilot, natural gas, and main injector are controlled by a central processing unit (CPU) or processor to feed the optimal mixture into the cylinder. Sample timing and duration are provided in Table A below for gasoline-CNG dual-fuel engines. As can be appreciated, the operating parameters will vary depending on the types of fuels being used, however, the timing sequence differs as compared to a diesel pilot dual fuel engine. The differences in these parameters may be implemented with supplemental CPU that piggybacks onto the vehicle CPU for timing of the first and second fuel injectors.

[0045] Turning now to exemplary FIG. 6, FIG. 6 displays an exemplary embodiment of a system diagram for an existing diesel fuel injection system 600. In an exemplary embodiment, diesel fuel may be provided in a diesel tank 602. In a next step, the diesel fuel in the diesel tank 602 may be extracted using a low pressure pump 604. The diesel fuel may then be passed through a filter 606, and then into a fuel injection pump 608, where it may then be pumped out through the fuel injectors 610. In an exemplary embodiment, residual diesel fuel in the fuel injection pump 608 may then be passed through the filter 606 again and back into the fuel injection pump 608.

[0046] Turning now to exemplary FIG. 7, FIG. 7 displays an exemplary embodiment of a system diagram for a diesel fuel injection system 700 that has been converted to a natural gas/pilot fuel system. In an exemplary embodiment, a pilot fuel system may be installed having essentially the same components as the previous diesel fuel system 600 previously used to inject fuel into the engine; in an exemplary embodiment, fuel may be provided in a pilot fuel tank 702. In a next step, the pilot fuel in the pilot fuel tank 702 may be extracted using a low pressure pump 704, for example, at 45 psi in the case of gasoline. The pilot fuel may then be passed through a filter 706, and then into a fuel injection pump 708, where it may then be pumped out through the fuel injectors 710, for example, at 5000 psi in the case of gasoline. In an exemplary embodiment, residual fuel in the fuel injection pump 708 may then be passed through the filter 706 again and back into the fuel injection pump 708.

[0047] Simultaneously, the natural gas/pilot fuel system may have a natural gas source 712 from which natural gas may be dispensed. In an exemplary embodiment, the natural gas source may dispense natural gas through a pressure regulator 714, which may be fed first to the fuel injection pump 716 and then to the fuel injectors 718. In an exemplary embodiment, the natural gas source may be compressed natural gas or it may be liquefied natural gas. In an exemplary embodiment the temperature of the high-pressure natural gas may be monitored as it is distributed to each injector. In an exemplary embodiment the flow rate of the natural gas is monitored as it is distributed to the injectors.

[0048] Controlling the injector timing may be accomplished by 1) modifying the program in the existing engine computer, 2) replacing the existing computer with another computer, or 3) integrating a new computer with the existing computer to take over the injector timing. Regardless of the method, the conversion may require additional wiring from the controlling computer(s) to the injectors and other devices in the vehicle (sensors, actuators, etc.).

[0049] According to an exemplary embodiment, a diesel engine to be converted may have an on-board diagnostic (OBD) system or control system, for example an OBD-II computer. In some exemplary embodiments, the OBD system may be coupled to one or more of the injectors, and may provide instructions to the injectors as to, for example, when to open, how long to stay open (based on, for example, an altitude or air pressure, outside ambient temperature, fuel type, whether the vehicle is under load, engine speed, compression ratio, engine stroke, or any other variable conditions), and so forth. In an exemplary embodiment wherein, an existing diesel engine is converted, the OBD system may be provided with new instructions as to how to control the injectors after the system has been converted, including, for example, instructions as to how to control the injectors when the system is in a startup phase and instructions as to how to control the injectors when the vehicle is past a startup phase and has moved to, for example, a standard burn cycle. The OBD system may also control, for example, the timing of the ignition of the natural gas, which may be triggered using the secondary starter plug, i.e. the pilot fluid. In an exemplary embodiment, a set of standard programs may be provided, each designed to reconfigure the OBD system of a particular engine or set of engines, which may be provided as part of a conversion kit, as may be desired.

TABLE-US-00001 TABLE A Injection timing Injection timing relative to TDC at relative to TDC idle at 1500 RPM Gasoline Pilot +5 degrees to 0 +10 degrees to Fuel Injector degrees (before 5 degrees TDC) Compressed +10 degrees to +15 +15 degrees to NG Main Fuel degrees 15 degrees Injector

[0050] The foregoing description and accompanying figures illustrate the principles, preferred embodiments and modes of operation of the invention. However, the invention should not be construed as being limited to the particular embodiments discussed above. Additional variations of the embodiments discussed above will be appreciated by those skilled in the art (for example, features associated with certain configurations of the invention may instead be associated with any other configurations of the invention, as desired).

[0051] Therefore, the above-described embodiments should be regarded as illustrative rather than restrictive. Accordingly, it should be appreciated that variations to those embodiments can be made by those skilled in the art without departing from the scope of the invention as defined by the following claims.