This uniquely improved device relates to a special Improved Durability Engine for Use with Stationary Power Generation Systems. Particularly this new special Improved Durability Engine Device is related to significantly improved component, materials and methods to improve the overall life and durability of conversion engines that are used with natural gas and other fuels.
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A special Improved Durability Engine device has been developed for use with Stationary Power Generation Systems. Particularly this new special Improved Durability Engine Device is related to improved component, materials and methods to improve the overall life and durability of conversion engines that are used with natural gas and other fuels. One skilled in the art of gensets and stationary power conversion well appreciates the improvements to durability shown herein.
The stationary power generation systems have been powered primarily by diesel and gasoline engines. The systems that are converted to natural gases or biologically produced alternatives such as methane and ethane, etc. have attempted to use existing gasoline and diesel powered engines. However, the change to a gas vapor system such as natural gas have revealed significant limitations in useful life—durability—prior to servicing the units. The improvements contained with this Soverns configuration and material uses greatly improve that durability for natural gas systems and the like.
The first found mention of turbosets remotely related to the Soverns device begins with U.S. Pat. No. 4,002,023 issued to Hartman (1977). It describes a stationary power-generating plant of the type which includes a turboset comprising an axial-flow combustion gas turbine, an axial flow combustion air compressor and a driven machine such as an electrical generator which are all coupled together and mounted for rotation about a common axis. No major durability improvements are addressed nor are elements of Soverns invention anticipated.
A U.S. Pat. No. 4,487,014 issued to Vinciguerra (1984) teaches a Gas generator and turbine unit. Here a gas turbine power unit is disclosed in which the arrangement and configuration of parts is such as to save space and weight in order to provide a compact and self-contained assembly. No major durability improvements are addressed nor anticipated.
A series of gas Systems for use of land fills and recyclable materials are shown in three patents to issued to Wikstrom, et al. U.S. Pat. No. 6,938,439 (2005) shows how gases are vented from a waste site such as a landfill, and the gases are separated into at least three streams comprising a hydrocarbon stream, a carbon dioxide stream, and residue stream. At least a portion of the carbon dioxide stream and hydrocarbon stream are liquefied or converted to a supercritical liquid used for cleaning. A U.S. Pat. Nos. 6,554,170 (2005) and 7,389,654 (2008) show similar gas conversion treatment at land fills for cleaning. No major durability improvements are addressed nor anticipated.
As far as known, there are no other improved or enhanced engine devices at the present time which fully provide these durability improvements to the drive mechanisms and power sources for stationary power generation systems. It is believed that this device is made with improved configuration of physical connections, resulting in a more durable design, with a better process of preparation and assembly, and with better material selections as compared to other currently utilized power systems for stationary generation of electricity and production of hot water.
A special Improved Durability Engine device has been developed for use with Stationary Power Generation Systems. Particularly this new special Improved Durability Engine Device is related to improved component, materials and methods to improve the overall life and durability of conversion engines that are used with natural gas and other fuels.
A new configuration has been developed for use with an 8.1 L gasoline powered engine or the like. The critical element for longer durability and field life are the cylinder heads. The “best in class” design, materials and assembly process will lead to the longest life for field use. The mass produced head castings are machined at a precision supplier and configured with a proprietary system of components. These components work together to support head life of approximately 16,000+ hours or more. This is at least a twofold increase to the present life of the engines when stationary and when powered by natural or LP gas.
The engine during operation is exposed to severe vibration, high levels of heat and corrosive materials from the fuel and water. These may be addressed by material selection, configuration of key parts such as the valves and seal, and dimensional control. Also, in the manufacturing operation, the preparation and assembly may expose the units to process irregularities that result in causing early wear and failures. This may be improved somewhat by material selection, configuration of key parts such as the valves and seats, and the dimensional control. Empirical test show that careful improvements to the preparation of the cylinder head assembly and “matching” of valves and seats can have significant improvement to durability capabilities and hence engine life.
The preferred embodiment of the special Improved Durability Engine Device is comprised essentially of improvements in four areas: material selection; process controls; special configurations of critical component parts for stationary natural gas units; and dimensional control of the component parts. The first improved change is Material Selection. The valves have special coatings and base materials. The seats have special base materials for improved life as described below. The second improved change is Process Controls such as the seat removal; seat insertion; seat contact with the register; exhaust guide interference and sealing; the lapping of valves and seats; removal of all debris in ports and registers; and checking heads with a vacuum or pressure test. The third improved change is with the Configurations of critical parts. The mating angles for valves and seats; the guide grooves; the cam configuration for smooth transition; the rotator spacer configured to eliminate rotation; and, preload on the valve spring by controlling its installed height. The fourth improved change is dimensional control of the component parts. These include items such as valve to seat concentricity; deck height; installed spring height; guide clearance; and valve to rocker arm angle. Several dimensions set for normal vehicle duty cycles are not precise enough to support the severe duty cycle of the stationary prime power generator fueled by natural or LP gas. These improvements are described in detail below.
There are several objects and advantages of the special Improved Durability Engine device. However, this new device has been developed for use with an 8.1 L standard gasoline powered. The device improvements enable this standard engine to be used with natural gas and the like. The overriding objective and empirical results are to achieve longer durability and field life on a consistent basis. These improvements offered by the special Improved Durability Engine device work together to support cylinder head life of approximately 16,000+ hours or more. This is at least a twofold increase to the present life of the engines when stationary and when powered by natural or LP gas.
Other advantages and additional features of the present special Improved Durability Engine device will be more apparent from the accompanying drawings and from the full description of the device. For one skilled in the art of devices and improvements for electrical power generation and the power sources and engines used to drive such systems, it is readily understood that the features shown in the examples with this mechanism are readily adapted for improvement to other types of engine drive systems.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate a preferred embodiment for the special Improved Durability Engine Device. The drawings together with the summary description given above and a detailed description given below serve to explain the principles of the special Improved Durability Engine Device. It is understood, however, that the device is not limited to only the precise arrangements and instrumentalities shown.
The following list refers to the drawings:
The present mechanism is a special Improved Durability Engine Device 31. The preferred embodiment of the special Improved Durability Engine Device is comprised essentially of improvements in four areas: material selection; process controls; special configurations of critical component parts for stationary natural gas units; and dimensional control of the component parts.
There is shown in
The first improved change is Material Selection. The valves 36,37 and seats 41, 41A have special coatings and base materials 42. The exhaust 36 and intake 37 valves are proprietary valves manufactured exclusively for Lloyd's Machine Shop by the Eaton Corporation. These valves 36, 37 are used only in the I Power 8.1 L natural gas engine 32. The heads of both valves 36, 37 are coated with cobalt based, hardened material for HD valves (like Stellite-1® or the like). The exhaust valve 36 base material is inconel or the like for high temperature performance, and the stem is silchrome or the like. The base material of the intake valve 37 is a high grade intake material. The stems of both valves 36, 37 are chrome plated to minimize friction and retain oil. The seat 41, 41A insert is a sintered tungsten carbide tool steel with additives to improve its high hot hardness for use in natural gas engines. Solid lubricants are built in to the material to prevent micro-welding which is the primary cause of valve recession. Special processing techniques are used for producing the seats 41, 41A. These include high temperature sintering and post heat treat processing which create “cermet” style metal alloy oxides in the material. They are called “cermet” because they do not soften at elevated temperatures (which is similar to ceramics), but they retain the machinability (which relates to metals). The preferred example of a seat 41, 41A (as an example and not a limitation) is called the 90000 series by its maker, the Dura-Bond Bearing Company of Carson City, Nev. The valve guides 44 are made of a high strength cast iron or the like with elements added for lubricity. The top end of the guide has a double groove feature 45 that mates directly with the radiused bands of the valve seal 46. This feature prevents the valve seal 46 from coming off of the guide 44 during operation, which could result in a guttered valve 36, 37 due to too much oil reaching the valve seat 40, 40A surface area or the seats 41, 41A themselves. The rotator eliminator spacer 47 is made of a sintered metal composition similar to that of valve guides 44. The valve spring 48 is made specifically for use in LPG/natural gas engines 32. It is made of a valve grade material. The preload on the spring 32 is determined by its installed height.
The second improved change is Process Controls. Several processing practices have a distinct effect on the durability of the cylinder head 31. Many processes will result in poor heat rejection in the completed cylinder head 31 if not done properly. In fact, all of the process controls listed below were discovered through failure analysis of actual cylinder heads 31.
The third improved change is with the Configurations of critical parts. The mating angles for valves 36, 37 and seats 41, 41A; the guide grooves 45; the cam 60 configuration for smooth transition; the rotator spacer 47 configured to eliminate rotation; and, preload on the valve spring 48 by controlling its installed height. The heads of both valves 36, 37 have a mating angle 43 between 15 and 45 degrees. The preferred embodiment has a mating angle 43 of approximately 30 degrees (for example and not limitation). The exhaust valve 36 is a 2 piece valve with a mid stem weld. The top end of the guide 44 has a double groove 45 feature that mates directly with the radiused bands of the valve seal 46. The cam 60 used in the I Power engine is specially designed for industrial applications. In place of the rotator spacer used by GM, the special Improved Durability Engine device uses a rotator eliminator spacer 47. The rotator eliminator 47 is made of a sintered metal composition or the like similar to that of valve guides 44. The valve spring 48 is made specifically for use in LPG/natural gas engines 32. It is made of a valve grade material. The preload on the spring 48 is determined by its installed height. Other valve train components used in the special Improved Durability Engine device 31 8.1 L natural gas engine 32 are standard OEM parts, including the push rod 72, the rocker arm 62 (with rocker ball 62A and nut 62B), the lifter 63, the spring retainer 64, and locks 65 (sometimes called “keepers”).
The fourth improved change is dimensional control of the component parts. Some dimensions of components in the special Improved Durability Engine device 31 greatly affect its durability. The identification of these dimensions is an empirical and analytical process that reveals the overall opportunities for improvement. Some dimensional controls that have been identified as important to the durability are: Valve 36,37 (seating area 40, 40A) to seat 41, 41A concentricity;
deck height;
installed spring 48 height;
guide 44 clearance; and
valve 36, 37 to rocker arm 62 angle.
In several cases, the dimension given by General Motors is satisfactory for passenger vehicle duty cycles, but is not precise enough to support the severe duty cycle of the prime power generator.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate a special Improved Durability Engine device 31 that is preferred. The drawings together with the summary description given above (especially as to materials and configurations) and a detailed description given below of the drawings and illustrations serve to explain the principles of the special Improved Durability Engine device 31. It is understood, however, that the special Improved Durability Engine device 31 is not limited to only the precise arrangements and instrumentalities shown.
All of the details mentioned here are exemplary and not limiting. Other specific components specific to describing a special Improved Durability Engine Device 31 may be added. For one skilled in the art of devices and improvements for electrical power generation and the power sources and engines used to drive such systems, it is readily understood that the features shown in the examples with this mechanism are readily adapted for improvement to other types of engine drive systems
The special Improved Durability Engine Device 31 has been described in the above embodiment. The manner of how the device operates is described below. One skilled in the art and field of electrical power generation and the drive engines for those systems will note that the description above and the operation described here must be taken together to fully illustrate the concept of the special Improved Durability Engine Device 31.
The operation of the preferred embodiment of the special Improved Durability Engine Device 31 is easily comprehended. The changes are incorporated in the manufacturing of the above described component parts and the preparation and assembly of the parts. The improvements to the process were described above.
The use and results of the improvements are described in
For a clear understanding of the empirical results in the testing of the special Improved Durability Engine device 31 an explanation and introduction to an early and exemplary case study may be helpful. The exemplary recipe (and not offered as a limitation) is multi-faceted: it consists of a combination of material choices, process disciplines, and dimensional control.
Valve Recession may be used as a Durability Metric A cylinder head 31A fails due to the gradual degradation of its ability to seal up the combustion chamber 53. The gradual wear of the valve seat 41, 41A and the head insert seat results in a leak that eventually prevents efficient combustion. This leak is the End of Life for the cylinder head 31A. Industry experts define the end of life as 0.180 inches or more of valve recession within one year or approximately 8000 hours of operation. If the valve recession trend runs below the line created by this specification, the cylinder head 31A is expected to last at least through one year of service life. Other lines can be drawn to indicate increased cylinder head life. Two years of cylinder head life is represented by the line from the origin to 0.180″ at 16,000 hours; three years is 0.180″ at 24,000 hours, and so on.
A case study is shown before and after the improvements. In
A further example in the case study is a Rank Order Analysis. To analyze the durability results of these two gensets, the data was organized into a Rank Order Analysis as for a partial factorial. Taking Unit 53, two corner and two center cylinders had been built with a powdered metal seat insert called the 90000 series made by Dura-Bond. The remaining two corner and two center cylinders had been built with a hardened steel seat made from J-loy or the like material, which was the current production seat at the time. J100 is a nickel based alloy with high chromium content. Parameters that remained constant among all cylinders were valve angle, valve seat material, and spring pressure.
As the cylinders were arranged in order from lowest recession to highest recession, it became obvious that the Dura-Bond 90K seat outperformed the J-loy J100 seat by a unanimous margin, showing a perfect end count.
Comparison of the worst Dura-Bond valve with the best J100 valve revealed that one valve had signs of rotating and the other did not. This prompted observation of all the valves for signs of rotation. Interestingly enough, within the same seat type family, the best valves had no signs of rotation and the worst valves had obviously rotated. This led to an investigation of the factors that cause a valve to rotate. Some rotation of a valve is necessary to knock off built up oil deposits on the valve seat. But, rotation can be detrimental when it becomes constant or severe. The valve begins to imitate a honing machine, and recession failure is imminent. Work is ongoing to identify stack up dimensions between the valve and rocker arm that encourage rotation of the valve. Once the root cause is identified, controls can be put in place to prevent the type of rotation that leads to early recession failure.
The secret recipe for long life cylinder heads consists of three important factors. All three essentially must be present to produce record setting durability for the stationary natural gas engine of the genset. The three factors are material compatibility, process controls, and dimensional controls.
Materials are the first ingredient. The exhaust and intake valves are proprietary valves manufactured by Eaton Corporation. They are used only in the 8.1 L natural gas engine. The head of both valves is coated with Stellite-1 (cobalt based, hardened material for HD valves) and has a 30 degree mating angle. The exhaust valve is a 2 piece valve with a mid stem weld. The exhaust base material is inconel for high temperature performance, and the stem is silchrome. The base material of the intake valve is a high grade intake material. The stem of both valves is chrome plated to minimize friction and retain oil. The seat insert is a sintered tungsten carbide tool steel with additives to improve its high hot hardness for use in natural gas engines. Solid lubricants are built in to the material to prevent micro-welding which is the primary cause of valve recession. Special processing techniques including high temperature sintering and post heat treat processing create “cermet” style metal alloy oxides in the material. They are called “cermet” because they do not soften at elevated temperatures, which is similar to ceramics, but they retain the machinability of metal. The seat is called the 90000 series by its maker, the Dura-Bond Bearing Company of Carson City, Nev. The valve guides are made of a high strength cast iron with elements added for lubricity. The top end of the guide has a double groove feature that mates directly with the radiused bands of the valve seal. This feature prevents the valve seal from coming off of the guide during operation, which could result in a guttered valve due to too much oil reaching the valve seat surface. In place of the rotator spacer used by GM, I Power uses a rotator eliminator spacer. It is made of a sintered metal composition similar to that of valve guides. The valve spring is made specifically for use in LPG/natural gas engines. It is made of a valve grade material. The preload on the spring is determined by its installed height. The cam used in the I Power engine is specially designed for industrial applications. Other valve train components used in the 8.1 L natural gas engine are standard OEM parts, including the push rod, the rocker arm (with rocker ball and nut), the lifter, the spring retainer, and locks (sometimes called “keepers”).
Process controls are the second ingredient. Several processing practices have a distinct effect on the durability of the cylinder head. Many processes will result in poor heat rejection in the completed cylinder head if not done properly. In fact, all of the process controls listed below were discovered through failure analysis of actual cylinder heads. These are:
Dimensional Controls are the third ingredient. Some dimensions in the I Power valve train greatly affect the durability of the cylinder head. Some examples that have been identified to date are valve to seat concentricity, deck height, installed spring height, guide clearance, and valve to rocker arm angle. In several cases, the dimension given by the vehicle manufacturer for their engine requirements is satisfactory for passenger vehicle duty cycles, but is not precise enough to support the severe duty cycle of the prime power generator.
A summary of this exemplary case study shows that thousands of hours of durability testing have pinpointed the material choices, process controls, and dimensional characteristics that have a high impact on cylinder head life. This knowledge has directed procedures and tolerances for optimum quality from our cylinder head suppliers. The result is extended service life for the genset and stationary power device.
With this description it is to be understood that the special Improved Durability Engine Device 31 is not to be limited to only the disclosed embodiment. The features of the special Improved Durability Engine Device 31 are intended to cover various modifications and equivalent arrangements included within the spirit and scope of the description.
This application claims the benefit of Provisional Patent Application Ser. No. 60/937,239 filed Jun. 25, 2007 by Laura M. Soverns and entitled “Special Improved Durability Engine Device for Use with Stationary Power Generation Systems”.
Number | Date | Country | |
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60937239 | Jun 2007 | US |