Hello Everyone,
I wanted to quickly pitch an idea for Harvester. Using a diesel-powered opposed-piston free-piston linear generator (FPLG) as the Harvester range extender provides several advantages and would make a true statement on the future of the auto industry. Obviously this is not a fully developed plan, and i am sure there are ways to make this better or flaws i have not considered or have not adequately explored. Consider this more of a pitch/brainstorming session for the FPLG Harvester.
The FPLG's design eliminates the need for a crankshaft and cylinder head, making it significantly smaller than traditional engines.
It can easily fit in a car, such as between the rear wheels or as I will suggest along the wheel base, without taking up excessive space or compromising the vehicle's design.
2. High Energy Density of Diesel Fuel:
Diesel offers much higher energy density than batteries, allowing the FPLG to extend the car’s range with a relatively small fuel tank.
This is particularly useful for long-distance trips, where refueling diesel is quick and efficient.
3. High Efficiency:
The opposed-piston configuration reduces heat losses, improving thermal efficiency.
The free-piston design allows for variable compression ratios, optimizing the combustion process for maximum energy output.
4. Low Vibrations:
The opposing pistons move symmetrically, canceling out many of the vibrational forces found in traditional engines.
This results in a quieter and smoother operation, ideal for enhancing passenger comfort.
5. Electric Integration:
The linear generator converts the pistons' motion directly into electricity, which can charge the battery or power electric motors seamlessly.
By functioning only as a battery charger rather than providing direct power to the drive motors, the FPLG avoids the complexity of integrating with the high-torque electric motor system.
This keeps the powertrain simple, with the FPLG operating independently of the drive motors and kicking in only when the battery pack needs charging.
This eliminates the mechanical complexity of traditional hybrid systems.
6. Performance Metrics:
With a small diesel tank (5 gallons), assuming an efficiency of ~35% (typical for high-efficiency diesel combustion engines), the FPLG could produce enough energy to generate 50–60 kWh of electricity. This could extend the car's range by 200–300 miles, depending on the vehicle's efficiency (e.g., 4 miles per kWh).
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The FPLG would have excellent fuel economy, consuming about 1 gallon of diesel per 50–60 kWh of electricity generated. In comparison, this far outperforms most traditional range extenders or small internal combustion engines in hybrids.
8. Energy Density:
Diesel’s high energy density (about 37.8 MJ/L) means that even a small 5-gallon tank provides a substantial range extension without significantly impacting weight or space.
This setup allows the vehicle to balance long-range capability with the convenience of a compact, fuel-efficient design.
9. Energy Management:
The FPLG could operate in top-off mode, running intermittently to maintain the battery at an optimal state of charge. This minimizes unnecessary fuel consumption and emissions while extending the usable life of the battery by avoiding deep discharges.
________________________________________
Modern diesel aftertreatment systems (e.g., Diesel Particulate Filters and Selective Catalytic Reduction for NOx) can help the FPLG meet stringent emissions standards like Euro 7 or CARB regulations.
By running intermittently to charge the battery, the system would minimize emissions compared to conventional combustion engines that operate continuously.
11. Fuel Flexibility:
In addition to conventional diesel, the FPLG could be designed to run on renewable diesel or synthetic e-fuels, making it future-proof and more environmentally friendly.
The opposed-piston design inherently reduces vibrations because the opposing pistons cancel out much of the motion-related forces.
With proper insulation and placement near the rear wheels, the FPLG's operation could be nearly silent, aligning with the quiet and smooth driving experience expected in EVs.
5. Cost and Manufacturing
13. Production Costs: The compact size of the FPLG and its separation from the drivetrain simplify the design and reduce production costs compared to complex hybrid systems with direct engine-to-wheel power links.
14. Scalability: The FPLG’s modular design can be adapted across multiple vehicle platforms, making it cost-effective for manufacturers to integrate into various models.
15. Maintenance Costs:
With fewer moving parts than a traditional engine (no crankshaft, camshaft, or valves), the FPLG requires less maintenance.
Occasional diesel aftertreatment servicing (e.g., DEF refills or filter cleaning) would be the primary upkeep.
________________________________________
Extended Range: ~200–300 miles of additional range from a 5-gallon diesel tank.
Compact Size: Fits between the rear wheels without sacrificing cabin space or frunk capacity.
High Efficiency: Fuel economy of ~50–60 kWh per gallon of diesel.
Low Vibrations and Noise: Quiet and smooth operation aligned with EV expectations.
Fuel Flexibility: Ability to run on renewable diesel or synthetic fuels for a greener footprint.
Here are a few ideas I had to deal with the heat generated:
1. Slowing the RPMs to Reduce Heat Generation
How It Works: By operating at lower RPMs, the FPLG would reduce the frequency of combustion events, thereby generating less heat overall.
Advantages:
Slower combustion cycles naturally reduce thermal stress and heat buildup.
Improved efficiency: At lower RPMs, combustion can be optimized for greater thermal efficiency by allowing more time for complete combustion and energy extraction.
Quieter operation: Lower RPMs would result in reduced noise, aligning with the EV's smooth and quiet profile.
Considerations:
Trade-off: Power output might decrease unless the stroke or fuel injection rate is optimized.
The linear generator might need slight redesigns to compensate for lower power output at slower piston speeds (e.g., by increasing the generator's coil windings to generate more electricity per stroke).
________________________________________
2. Using Lower-Temperature Combustion
How It Works: Lowering the combustion temperature through techniques like lean-burn operation (high air-to-fuel ratio), Exhaust Gas Recirculation (EGR), or advanced fuel injection strategies.
Advantages:
Lean Combustion: Reduces peak combustion temperatures, resulting in less heat transfer to surrounding components and lower NOx emissions.
EGR: Recirculating a portion of exhaust gases back into the combustion chamber reduces oxygen concentration and peak combustion temperatures.
Fuel Flexibility: A low-temperature combustion approach could be designed to work with alternative fuels (e.g., biodiesel or synthetic fuels), further reducing heat and emissions.
Considerations:
Lean or low-temperature combustion may reduce specific power output, requiring careful tuning to balance power needs and thermal management.
This method may increase particulate matter emissions unless paired with advanced diesel particulate filters (DPFs).
________________________________________
3. Using a Heat Sink with Aluminum and Vehicle Frame
How It Works: The FPLG could include an aluminum heat sink directly attached to its casing. This sink could transfer heat to the vehicle’s frame, where the mass and surface area can help dissipate it.
Advantages:
Aluminum is lightweight and highly thermally conductive, making it a great material for heat sinks.
Leveraging the vehicle frame as a thermal mass could spread out heat dissipation over a larger area, reducing localized hotspots.
No moving parts: A heat sink is a passive system, making it reliable and maintenance-free.
Considerations:
The vehicle frame would need to be designed to handle thermal loads without compromising structural integrity or causing hot spots in areas sensitive to heat (e.g., near wiring or plastics).
Aluminum heat sinks must be carefully sized to avoid excessive weight or space consumption.
________________________________________
You also don’t need to rely on a single solution—these approaches can be combined for maximum effectiveness:
Lower RPMs + Low-Temperature Combustion:
Lowering RPMs reduces the frequency of combustion, while low-temperature combustion minimizes the heat generated per cycle. Together, this combination reduces the thermal load on the system without compromising reliability.
A carefully calibrated lean-burn strategy could maintain power output even at reduced RPMs.
Heat Sink + Frame Integration:
Pair a well-designed aluminum heat sink with a strategic connection to the vehicle’s rear frame, allowing heat to dissipate passively.
Include thermal insulators (like ceramic coatings) at critical junctions to protect sensitive components.
Supplementary Liquid Cooling (Optional):
If heat loads still exceed acceptable levels, a lightweight liquid cooling system could be added to remove heat from areas that the heat sink can’t effectively manage.
Thermal Coatings: Coat the inside of the combustion chamber and piston surfaces with ceramic or thermal-barrier coatings to reflect heat back into the combustion process, reducing heat transfer to the engine block.
Exhaust Heat Recovery: Use an exhaust heat exchanger to recover waste heat for auxiliary uses, like cabin heating, or convert it into electricity through a thermoelectric generator.
________________________________________
I think there is also a lot of potential in using two opposed-piston free-piston linear generators (FPLGs) running lengthwise along the sides of the car. Which would confer the following advantages:
Thermodynamic efficiency: Better expansion of combustion gases, leading to higher energy extraction.
Generator efficiency: A longer piston travel allows for greater magnetic field traversal over the generator coils, improving energy recovery during each stroke.
17. Improved Power Output: The larger stroke increases the energy produced per combustion event, allowing the engines to run more slowly while maintaining adequate power to charge the battery.
________________________________________
Dynamic Balancing: Since each FPLG is already balanced internally (due to the opposed-piston design), the opposing placement along the car further enhances overall vibration suppression.
________________________________________
You preserve the frunk and trunk space, which are important to customers.
The space between the rear wheels can still house the diesel tank, auxiliary systems, or a small liquid cooling radiator for thermal management.
Accessibility: This placement provides easy access for maintenance or repairs, as the FPLGs can be reached from underneath the car or through removable side panels.
________________________________________
Longer FPLGs dissipate heat over a larger surface area, reducing hotspots.
The engines' placement along the sides allows for airflow underneath the car to assist in cooling.
Aluminum heat sinks attached to the FPLGs could transfer heat into the chassis rails, using the car's structure as a thermal mass.
Passive and Active Cooling: If additional cooling is needed, liquid cooling radiators could be mounted near the rear or sides of the vehicle, leveraging airflow from the car's motion.
________________________________________
Higher power output for larger vehicles or high-demand situations.
Redundancy: If one FPLG fails, the other can still provide power, ensuring reliability.
Silent Operation in EV Mode: The FPLGs would only operate intermittently to charge the battery in "Top off Mode", preserving the quiet, smooth operation of the electric drivetrain most of the time.
In conclusion, by maintaining the frunk and trunk (or bed for Terra) while offering extended range via efficient diesel operation, this design addresses the practical concerns of EV owners who need long-range flexibility without sacrificing storage space.
I wanted to quickly pitch an idea for Harvester. Using a diesel-powered opposed-piston free-piston linear generator (FPLG) as the Harvester range extender provides several advantages and would make a true statement on the future of the auto industry. Obviously this is not a fully developed plan, and i am sure there are ways to make this better or flaws i have not considered or have not adequately explored. Consider this more of a pitch/brainstorming session for the FPLG Harvester.
Key Advantages:
1. Compact Size:The FPLG's design eliminates the need for a crankshaft and cylinder head, making it significantly smaller than traditional engines.
It can easily fit in a car, such as between the rear wheels or as I will suggest along the wheel base, without taking up excessive space or compromising the vehicle's design.
2. High Energy Density of Diesel Fuel:
Diesel offers much higher energy density than batteries, allowing the FPLG to extend the car’s range with a relatively small fuel tank.
This is particularly useful for long-distance trips, where refueling diesel is quick and efficient.
3. High Efficiency:
The opposed-piston configuration reduces heat losses, improving thermal efficiency.
The free-piston design allows for variable compression ratios, optimizing the combustion process for maximum energy output.
4. Low Vibrations:
The opposing pistons move symmetrically, canceling out many of the vibrational forces found in traditional engines.
This results in a quieter and smoother operation, ideal for enhancing passenger comfort.
5. Electric Integration:
The linear generator converts the pistons' motion directly into electricity, which can charge the battery or power electric motors seamlessly.
By functioning only as a battery charger rather than providing direct power to the drive motors, the FPLG avoids the complexity of integrating with the high-torque electric motor system.
This keeps the powertrain simple, with the FPLG operating independently of the drive motors and kicking in only when the battery pack needs charging.
This eliminates the mechanical complexity of traditional hybrid systems.
6. Performance Metrics:
With a small diesel tank (5 gallons), assuming an efficiency of ~35% (typical for high-efficiency diesel combustion engines), the FPLG could produce enough energy to generate 50–60 kWh of electricity. This could extend the car's range by 200–300 miles, depending on the vehicle's efficiency (e.g., 4 miles per kWh).
________________________________________
2. Efficiency and Energy Usage
7. Fuel Economy:The FPLG would have excellent fuel economy, consuming about 1 gallon of diesel per 50–60 kWh of electricity generated. In comparison, this far outperforms most traditional range extenders or small internal combustion engines in hybrids.
8. Energy Density:
Diesel’s high energy density (about 37.8 MJ/L) means that even a small 5-gallon tank provides a substantial range extension without significantly impacting weight or space.
This setup allows the vehicle to balance long-range capability with the convenience of a compact, fuel-efficient design.
9. Energy Management:
The FPLG could operate in top-off mode, running intermittently to maintain the battery at an optimal state of charge. This minimizes unnecessary fuel consumption and emissions while extending the usable life of the battery by avoiding deep discharges.
________________________________________
3. Environmental and Regulatory Concerns
10. Emissions:Modern diesel aftertreatment systems (e.g., Diesel Particulate Filters and Selective Catalytic Reduction for NOx) can help the FPLG meet stringent emissions standards like Euro 7 or CARB regulations.
By running intermittently to charge the battery, the system would minimize emissions compared to conventional combustion engines that operate continuously.
11. Fuel Flexibility:
In addition to conventional diesel, the FPLG could be designed to run on renewable diesel or synthetic e-fuels, making it future-proof and more environmentally friendly.
4. Customer Experience
12. Noise, Vibration, and Harshness (NVH):The opposed-piston design inherently reduces vibrations because the opposing pistons cancel out much of the motion-related forces.
With proper insulation and placement near the rear wheels, the FPLG's operation could be nearly silent, aligning with the quiet and smooth driving experience expected in EVs.
5. Cost and Manufacturing
13. Production Costs: The compact size of the FPLG and its separation from the drivetrain simplify the design and reduce production costs compared to complex hybrid systems with direct engine-to-wheel power links.
14. Scalability: The FPLG’s modular design can be adapted across multiple vehicle platforms, making it cost-effective for manufacturers to integrate into various models.
15. Maintenance Costs:
With fewer moving parts than a traditional engine (no crankshaft, camshaft, or valves), the FPLG requires less maintenance.
Occasional diesel aftertreatment servicing (e.g., DEF refills or filter cleaning) would be the primary upkeep.
________________________________________
Summary of Design Advantages
By using the opposed-piston FPLG as a range extender, the car can achieve:Extended Range: ~200–300 miles of additional range from a 5-gallon diesel tank.
Compact Size: Fits between the rear wheels without sacrificing cabin space or frunk capacity.
High Efficiency: Fuel economy of ~50–60 kWh per gallon of diesel.
Low Vibrations and Noise: Quiet and smooth operation aligned with EV expectations.
Fuel Flexibility: Ability to run on renewable diesel or synthetic fuels for a greener footprint.
Here are a few ideas I had to deal with the heat generated:
1. Slowing the RPMs to Reduce Heat Generation
How It Works: By operating at lower RPMs, the FPLG would reduce the frequency of combustion events, thereby generating less heat overall.
Advantages:
Slower combustion cycles naturally reduce thermal stress and heat buildup.
Improved efficiency: At lower RPMs, combustion can be optimized for greater thermal efficiency by allowing more time for complete combustion and energy extraction.
Quieter operation: Lower RPMs would result in reduced noise, aligning with the EV's smooth and quiet profile.
Considerations:
Trade-off: Power output might decrease unless the stroke or fuel injection rate is optimized.
The linear generator might need slight redesigns to compensate for lower power output at slower piston speeds (e.g., by increasing the generator's coil windings to generate more electricity per stroke).
________________________________________
2. Using Lower-Temperature Combustion
How It Works: Lowering the combustion temperature through techniques like lean-burn operation (high air-to-fuel ratio), Exhaust Gas Recirculation (EGR), or advanced fuel injection strategies.
Advantages:
Lean Combustion: Reduces peak combustion temperatures, resulting in less heat transfer to surrounding components and lower NOx emissions.
EGR: Recirculating a portion of exhaust gases back into the combustion chamber reduces oxygen concentration and peak combustion temperatures.
Fuel Flexibility: A low-temperature combustion approach could be designed to work with alternative fuels (e.g., biodiesel or synthetic fuels), further reducing heat and emissions.
Considerations:
Lean or low-temperature combustion may reduce specific power output, requiring careful tuning to balance power needs and thermal management.
This method may increase particulate matter emissions unless paired with advanced diesel particulate filters (DPFs).
________________________________________
3. Using a Heat Sink with Aluminum and Vehicle Frame
How It Works: The FPLG could include an aluminum heat sink directly attached to its casing. This sink could transfer heat to the vehicle’s frame, where the mass and surface area can help dissipate it.
Advantages:
Aluminum is lightweight and highly thermally conductive, making it a great material for heat sinks.
Leveraging the vehicle frame as a thermal mass could spread out heat dissipation over a larger area, reducing localized hotspots.
No moving parts: A heat sink is a passive system, making it reliable and maintenance-free.
Considerations:
The vehicle frame would need to be designed to handle thermal loads without compromising structural integrity or causing hot spots in areas sensitive to heat (e.g., near wiring or plastics).
Aluminum heat sinks must be carefully sized to avoid excessive weight or space consumption.
________________________________________
You also don’t need to rely on a single solution—these approaches can be combined for maximum effectiveness:
Lower RPMs + Low-Temperature Combustion:
Lowering RPMs reduces the frequency of combustion, while low-temperature combustion minimizes the heat generated per cycle. Together, this combination reduces the thermal load on the system without compromising reliability.
A carefully calibrated lean-burn strategy could maintain power output even at reduced RPMs.
Heat Sink + Frame Integration:
Pair a well-designed aluminum heat sink with a strategic connection to the vehicle’s rear frame, allowing heat to dissipate passively.
Include thermal insulators (like ceramic coatings) at critical junctions to protect sensitive components.
Supplementary Liquid Cooling (Optional):
If heat loads still exceed acceptable levels, a lightweight liquid cooling system could be added to remove heat from areas that the heat sink can’t effectively manage.
Thermal Coatings: Coat the inside of the combustion chamber and piston surfaces with ceramic or thermal-barrier coatings to reflect heat back into the combustion process, reducing heat transfer to the engine block.
Exhaust Heat Recovery: Use an exhaust heat exchanger to recover waste heat for auxiliary uses, like cabin heating, or convert it into electricity through a thermoelectric generator.
________________________________________
I think there is also a lot of potential in using two opposed-piston free-piston linear generators (FPLGs) running lengthwise along the sides of the car. Which would confer the following advantages:
1. Increased Stroke Length and Efficiency
16. Longer Stroke Advantage: By extending the FPLGs lengthwise from behind the front wheel to just in front of the rear wheel, the stroke length could be significantly increased compared to a more compact flat design. A longer stroke improves:Thermodynamic efficiency: Better expansion of combustion gases, leading to higher energy extraction.
Generator efficiency: A longer piston travel allows for greater magnetic field traversal over the generator coils, improving energy recovery during each stroke.
17. Improved Power Output: The larger stroke increases the energy produced per combustion event, allowing the engines to run more slowly while maintaining adequate power to charge the battery.
________________________________________
2. Balance and Reduced Vibration:
Opposing Forces: Placing the two FPLGs on opposite sides of the car balances the forces generated by the pistons' motion. This symmetry cancels out vibrations and ensures the vehicle remains smooth and quiet, even during operation.Dynamic Balancing: Since each FPLG is already balanced internally (due to the opposed-piston design), the opposing placement along the car further enhances overall vibration suppression.
________________________________________
3. Space Utilization:
Efficient Use of Side Chassis Space: The sides of the vehicle, along the rocker panels, are generally underutilized in most car designs. By running the FPLGs along the length of the chassis:You preserve the frunk and trunk space, which are important to customers.
The space between the rear wheels can still house the diesel tank, auxiliary systems, or a small liquid cooling radiator for thermal management.
Accessibility: This placement provides easy access for maintenance or repairs, as the FPLGs can be reached from underneath the car or through removable side panels.
________________________________________
4. Thermal Management:
Distributed Heat Dissipation:Longer FPLGs dissipate heat over a larger surface area, reducing hotspots.
The engines' placement along the sides allows for airflow underneath the car to assist in cooling.
Aluminum heat sinks attached to the FPLGs could transfer heat into the chassis rails, using the car's structure as a thermal mass.
Passive and Active Cooling: If additional cooling is needed, liquid cooling radiators could be mounted near the rear or sides of the vehicle, leveraging airflow from the car's motion.
________________________________________
5. Energy Output and Redundancy:
Parallel Operation: Each FPLG operates independently to charge the same battery pack. This setup ensures:Higher power output for larger vehicles or high-demand situations.
Redundancy: If one FPLG fails, the other can still provide power, ensuring reliability.
Silent Operation in EV Mode: The FPLGs would only operate intermittently to charge the battery in "Top off Mode", preserving the quiet, smooth operation of the electric drivetrain most of the time.
In conclusion, by maintaining the frunk and trunk (or bed for Terra) while offering extended range via efficient diesel operation, this design addresses the practical concerns of EV owners who need long-range flexibility without sacrificing storage space.
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You’re not the first to suggest it. I’m not interested in diesel personally (I reserved a Harvester, but will probably end up changing my reservation to straight-EV eventually), but a lot of other folks here have said they’re interested in it.
