Opposed Piston Diesel Engine - Revision history

Adamcolton at 15:46, 28 August 2019

2019-08-28T15:46:08Z

← Older revision		Revision as of 15:46, 28 August 2019
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	Half-baked idea.		Half-baked idea.

	I've been looking at [https://en.wikipedia.org/wiki/Opposed-piston_engine Opposed-piston_engines] and I'm interested in them, particularly the [https://en.wikipedia.org/wiki/Six-stroke_engine#M4.2B2 M4+2]. I really like [https://www.youtube.com/watch?v=pGaISFg_ZIw this] one and [https://www.youtube.com/watch?v=9Gcaoel6QFY this too]. This is my try at designing one.		I've been looking at [https://en.wikipedia.org/wiki/Opposed-piston_engine Opposed-piston_engines] and I'm interested in them, particularly the [https://en.wikipedia.org/wiki/Six-stroke_engine#M4.2B2 M4+2]. I really like [https://www.youtube.com/watch?v=pGaISFg_ZIw this] one and [https://www.youtube.com/watch?v=9Gcaoel6QFY this too], oh [https://www.youtube.com/watch?v=UF5j1DvC954 and this one]. This is my try at designing one.

	A different approach: http://www.gizmag.com/duke-engines-axial/33631/ or this: https://www.youtube.com/watch?v=aZB0Go3Kj-k		A different approach: http://www.gizmag.com/duke-engines-axial/33631/ or this: https://www.youtube.com/watch?v=aZB0Go3Kj-k

Adamcolton: /* Valves and Air Flow */

2016-04-27T21:41:12Z

Valves and Air Flow

← Older revision		Revision as of 21:41, 27 April 2016
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	== Valves and Air Flow ==		== Valves and Air Flow ==
	There are 4 air states; closed (CL) high pressure (HP), atmosphere out (AO) and atmosphere in (AI). High pressure goes to air tank, though I need to look at this because the exhaust may be too dirty to use directly.		There are 4 air states; closed (CL) high pressure (HP), atmosphere out (AO) and atmosphere in (AI). High pressure goes to air tank, though I need to look at this because the exhaust may be too dirty to use directly. The two options are to either filter it or use it drive a secondary pump that won't be sensitive to the particulate. I'm leaning towards the filter though, because it should be easier and it would make this a bit cleaner to operate.

	There are two valves, one inside (I) the pistons, with the two outer (O) sections connected together to a single valve. The outer valves are located just past the last winding, but a gap is left beyond that with will turn into a high pressure spring if the pistons over shoot.		There are two valves, one inside (I) the pistons, with the two outer (O) sections connected together to a single valve. The outer valves are located just past the last winding, but a gap is left beyond that with will turn into a high pressure spring if the pistons over shoot.

Adamcolton: /* Electronic Control */

2016-04-27T21:34:06Z

Electronic Control

← Older revision		Revision as of 21:34, 27 April 2016
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	== Electronic Control ==		== Electronic Control ==
			I'd really like it if this could be controlled by an AT-Tiny-85, 6 IO pins. But I don't think that's possible because of the complexity of the winding control.
	I'd really like it if this could be controlled by an AT-Tiny-85, 6 IO pins.

	=== Mode Select ===		=== Mode Select ===
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	=== Winding Control ===		=== Winding Control ===
	This actually gets pretty complex. Each winding has 3 modes; driving, powering and sensing.		This actually gets pretty complex. Each winding has 3 modes; driving, powering and sensing.

			The power stroke is very brief so I need to get as much energy out of it as possible. I think each coil needs it's own bridge rectifier, with the DC side of all of them wired in series. Then I think I need something like a charge pump, but I'm not sure. Fortunately power mode is all or nothing, so I can just disconnect the windings from the control circuit when that happens.

	The driving circuit needs to be adjustable, because different driving operations will require different amounts of power. I also need to deal with discharge and rapidly switching polarization. I'll probably have to look at resonant capacitors. Good excuse to look at Gauss guns.		The driving circuit needs to be adjustable, because different driving operations will require different amounts of power. I also need to deal with discharge and rapidly switching polarization. I'll probably have to look at resonant capacitors. Good excuse to look at Gauss guns.
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	Sensing will be used during compression to get the position of the pistons. I'll have to experiment with this because I think there will be a current induced from the neighboring coil, but I need to detect when the piston is entering the coil.		Sensing will be used during compression to get the position of the pistons. I'll have to experiment with this because I think there will be a current induced from the neighboring coil, but I need to detect when the piston is entering the coil.

	~~Powering will also have it's complexities. The power stroke is very brief so~~ I ~~need~~ to ~~get as much energy out of it as possible. I think each coil needs it's own bridge rectifier,~~ with the ~~DC side of all of them wired in series~~. ~~Then I think I need something like a charge pump, but~~ I'm not sure.		I think the best design to cope with this is to use a single PWM pin to set the power level and then assign each wire to a pin. I'm not sure how make a single pin work for sensing and driving.

Adamcolton: /* Electronic Control */

2016-04-27T21:26:25Z

Electronic Control

@@ Line 77: / Line 77: @@
 == Electronic Control ==
-The rest of the pins would be used to Charlie-plex the valve solenoids.
+I'd really like it if this could be controlled by an AT-Tiny-85, 6 IO pins.
 States:
@@ Line 92: / Line 103: @@
 I'll need to pin this out, but I'm sure I can do it with 4, I may be able to do it with 3.
-That leaves either 1 or 2 pins. It looks like the At-Tiny-85 has 2 or 3 ADCs which means I can use one of them to set the compression ratio.
+=== Winding Control ===

Adamcolton: /* Electronic Control */

2016-04-27T21:04:07Z

Electronic Control

← Older revision		Revision as of 21:04, 27 April 2016
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	# I:HP/O:AO		# I:HP/O:AO
	# I:CL/O:HP		# I:CL/O:HP

			I'll need to pin this out, but I'm sure I can do it with 4, I may be able to do it with 3.

			That leaves either 1 or 2 pins. It looks like the At-Tiny-85 has 2 or 3 ADCs which means I can use one of them to set the compression ratio.

Adamcolton at 20:59, 27 April 2016

2016-04-27T20:59:20Z

@@ Line 9: / Line 9: @@
 == Pistons ==
-The pistons are opposed in a single chamber. The pistons are ringed in permanent magnets, rare Earth. I'll probably make the core out of steel to help with the magnetic field. To be lighter, the pistons should sort of cup shaped.
+The pistons are opposed in a single chamber. To be lighter, the pistons should sort of cup shaped.
 I'd like to see if the pistons can be machined with enough precision to not need rings. A v2 improvement would be looking at ways to reduce friction with something like fluid bearings.
@@ Line 17: / Line 23: @@
 == Valves and Air Flow ==
-There are 3 air states; high pressure (HP), atmosphere out (AO) and atmosphere in (AI). Fuel is injected at a constant, but adjustable rate to atmosphere in.
+There are 4 air states; closed (CL) high pressure (HP), atmosphere out (AO) and atmosphere in (AI). High pressure goes to air tank, though I need to look at this because the exhaust may be too dirty to use directly.
-There are two valves, one inside (I) the pistons, with the two outer (O) sections connected together to a single valve.
+There are two valves, one inside (I) the pistons, with the two outer (O) sections connected together to a single valve. The outer valves are located just past the last winding, but a gap is left beyond that with will turn into a high pressure spring if the pistons over shoot.
-This gives us 9 states, but I'm not sure how many are actually used:
+Atmosphere In is separate for I and O. For I, fuel is fed at a constant rate (constant with result to engine timing, but adjustable overall).
 == Combustion Operation ==

Adamcolton at 20:21, 27 April 2016

2016-04-27T20:21:04Z

← Older revision		Revision as of 20:21, 27 April 2016
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	A different approach: http://www.gizmag.com/duke-engines-axial/33631/ or this: https://www.youtube.com/watch?v=aZB0Go3Kj-k		A different approach: http://www.gizmag.com/duke-engines-axial/33631/ or this: https://www.youtube.com/watch?v=aZB0Go3Kj-k

	== Goals ==		== Goals ==
	The goal of the engine is to simplify design. With a focus on fewer parts and easier to fix. Because of CNC manufacturing, the solid parts can be complex and precise, so long as replacing them is simple.		The goal of the engine is to simplify design. With a focus on fewer parts and easier to fix. Because of CNC manufacturing, the solid parts can be complex and precise, so long as replacing them is simple.

	~~This is interesting, and simple: https://www.youtube.com/watch?v=OwL7gApJhjw~~

	== Pistons ==		== Pistons ==
	The pistons are opposed in a single chamber. I'~~d like~~ to ~~see if the pistons can be machined~~ with ~~enough precision to not need rings.~~		The pistons are opposed in a single chamber. The pistons are ringed in permanent magnets, rare Earth. I'll probably make the core out of steel to help with the magnetic field. To be lighter, the pistons should sort of cup shaped.

	~~Even further in~~ the ~~half baked ideas would be to intentionally leave a very small gap (sub millimeter) to reduce friction~~. ~~The pistons could~~ be ~~aligned either with air pressure or magnetism (particularly induction).~~

	~~== Timing Profile ==~~
	~~I drew out~~ the ~~timing profile, and I think it's possible, though it's interesting~~.

	~~The piston chamber has a opening at either end for intake and outlet, but no valves. There is a fuel injector closer~~ to the ~~intake side~~. ~~P1 is the piston on the intake side and P2 is on the outlet side. Position I is the outside edge of the inlet, C is the center (and the point of combustion) and O is the far side of the outlet~~.		I'd like to see if the pistons can be machined with enough precision to not need rings. A v2 improvement would be looking at ways to reduce friction with something like fluid bearings.

	I think the piston ~~cams will be wedged between two camshafts - one to push~~ and ~~one to pull~~.		== Cylinder ==
			The outside of the cylinder will be steel pipe. I'll make an inner core of wound enable copper wire, with several stages (I'd guess 6). The inner layer will be smoothed with high temperature epoxy. I think the best approach is to make a wax cylinder the exact size of the piston, and then melt it out after the epoxy has set.

	==~~= Intake~~ and ~~Combustion=~~==		== Valves and Air Flow ==
	~~Intake begins with the pistons touching~~. P2 is ~~driven by~~ a ~~cam linearly from I to C. When P2 is halfway through this motion, P1 beings moving, also linearly~~, but ~~at twice the speed. The result being that P1 and P2 begin with no gap under the intake, a gap opens up, then closes towards the center. The fuel injector is timed~~ to ~~fire just after P1 closes the intake. The pistons come close enough to compress the air and begin diesel combustion~~.		There are 3 air states; high pressure (HP), atmosphere out (AO) and atmosphere in (AI). Fuel is injected at a constant, but adjustable rate to atmosphere in.

	~~The compression ration needs~~ to ~~be about 25:1~~.		There are two valves, one inside (I) the pistons, with the two outer (O) sections connected together to a single valve.

	~~It may also make sense to put the fuel injector just outside the intake and fire it just as P2 begins to move.~~		This gives us 9 states, but I'm not sure how many are actually used:
			# I:HP/O:HP
			# I:HP/O:AO
			# I:HP/O:AI
			# I:AO/O:HP
			# I:AO/O:AO
			# I:AO/O:AI
			# I:AI/O:HP
			# I:AI/O:AO
			# I:AI/O:AI

	=== ~~Expansion~~ ===		== Combustion Operation ==
	~~At this point rather than the cam driving the pistons, the pistons switch over to deliver power. So the~~

Adamcolton at 18:39, 27 April 2016

2016-04-27T18:39:47Z

← Older revision		Revision as of 18:39, 27 April 2016
Line 6:		Line 6:
	== Goals ==		== Goals ==
	The goal of the engine is to simplify design. With a focus on fewer parts and easier to fix. Because of CNC manufacturing, the solid parts can be complex and precise, so long as replacing them is simple.		The goal of the engine is to simplify design. With a focus on fewer parts and easier to fix. Because of CNC manufacturing, the solid parts can be complex and precise, so long as replacing them is simple.

			This is interesting, and simple: https://www.youtube.com/watch?v=OwL7gApJhjw

	== Pistons ==		== Pistons ==

Adamcolton at 18:28, 27 April 2016

2016-04-27T18:28:35Z

← Older revision		Revision as of 18:28, 27 April 2016
Line 1:		Line 1:
	Half-baked idea.		Half-baked idea.

	I've been looking at [https://en.wikipedia.org/wiki/Opposed-piston_engine Opposed-piston_engines] and I'm interested in them, particularly the [https://en.wikipedia.org/wiki/Six-stroke_engine#M4.2B2 M4+2]. I really like [~~http~~://www.youtube.com/watch?v=pGaISFg_ZIw this] one and [~~http~~://www.youtube.com/watch?v=9Gcaoel6QFY this too]. This is my try at designing one.		I've been looking at [https://en.wikipedia.org/wiki/Opposed-piston_engine Opposed-piston_engines] and I'm interested in them, particularly the [https://en.wikipedia.org/wiki/Six-stroke_engine#M4.2B2 M4+2]. I really like [https://www.youtube.com/watch?v=pGaISFg_ZIw this] one and [https://www.youtube.com/watch?v=9Gcaoel6QFY this too]. This is my try at designing one.

	A different approach: http://www.gizmag.com/duke-engines-axial/33631/ or this: https://www.youtube.com/watch?v=aZB0Go3Kj-k		A different approach: http://www.gizmag.com/duke-engines-axial/33631/ or this: https://www.youtube.com/watch?v=aZB0Go3Kj-k

Adamcolton at 18:28, 27 April 2016

2016-04-27T18:28:16Z

← Older revision		Revision as of 18:28, 27 April 2016
Line 1:		Line 1:
	Half-baked idea.		Half-baked idea.

	I've been looking at [https://en.wikipedia.org/wiki/Opposed-piston_engine Opposed-piston_engines] and I'm interested in them, particularly the [https://en.wikipedia.org/wiki/Six-stroke_engine#M4.2B2 M4+2]. I really like [~~https~~://www.youtube.com/watch?v=pGaISFg_ZIw this] one and [~~https~~://www.youtube.com/watch?v=9Gcaoel6QFY this too]. This is my try at designing one.		I've been looking at [https://en.wikipedia.org/wiki/Opposed-piston_engine Opposed-piston_engines] and I'm interested in them, particularly the [https://en.wikipedia.org/wiki/Six-stroke_engine#M4.2B2 M4+2]. I really like [http://www.youtube.com/watch?v=pGaISFg_ZIw this] one and [http://www.youtube.com/watch?v=9Gcaoel6QFY this too]. This is my try at designing one.

	A different approach: http://www.gizmag.com/duke-engines-axial/33631/ or this: https://www.youtube.com/watch?v=aZB0Go3Kj-k		A different approach: http://www.gizmag.com/duke-engines-axial/33631/ or this: https://www.youtube.com/watch?v=aZB0Go3Kj-k