On the other hand, have you considered that according to his son, he intended to put this motor in his car and use the stock drive train? Doesn't that do away with the notion of a constant low rpm?
The patent is for an air compressor. A stock drivetrain can be driven by a separate conventional air motor using the excess air produced by the air compressor. The exhaust from the conventional air motor not being recycled. The two motor cylinders shown on patent are only for driving the air compressor. That is a possibility also.
I found this description of Neal's firing order, written a few years ago. It would be extremely helpful if someone would check this and independently confirm the firing order, only thing needed is to look at Neal's patent drawing of the compressor crank arms and the crankshaft.
I'm not sure what you're looking for in terms of an independent confirmation, but, FWIW, my efforts to work through the problem on my own led me to arrive at the same (assumed) compression order for the right bank.
I was stumped by Fig. 4 for a while until I added the assumption that the first crankpin is actually at the top of the circle described by the shaft's rotation. Because the pins for the power cylinders are drawn as *flush* to the surrounding crank arms when at the top and bottom of their rotation, and the pin of the first compression cylinder is not shown as flush, I was hung up on the idea that this pin was not at the top of the circle, but rotated to some extent to account for the fact it seemed to be sitting down lower between the crank arms. This notion was further reinforced by the fact Fig. 2 above shows the pin rotated to place the piston at top dead center of the right cylinder, and I thought the two drawings were intended to correspond. Then I finally realized Fig. 3 was also drawn with the piston at top dead center regardless of the pin's location on the crankshaft in Fig. 4.
Still working on this as time permits. The peaks from the piston pair per throw are going to be two points on a longer combined pulse, rather than distinct pulses. The outflow from each cylinder has varying mass/flow rates even if the discharge pressure is fairly constant, and the highest flow rate is way before TDC and BDC of the pistons.
Yes, agree the peaks are not sharp in time, so the whole crankshaft balance worry may not be a big concern. The firing order still applies though, just for example picking the rounded peak as the reference. It does not matter where the peak is on the stroke since all the cylinders will behave the same, then the firing order is just shifted.
I drew the crank out and came up with the same physical sequence and the only thing I can add at this time is the location sequence of the pins on the crank starting with pin 1 on the left. I came up with eight unique combinations. This is aside from the firing order. The firing order doesn't change, just the location they occur on the length of the crank. As Renny noted there are two possible orders for each level of pins, meaning 2 & 7, 3 & 6, 4 & 5 can be swapped, 7 with 2 etc. Two of the sequences are straight, 1 through 7 or 7 to 1.
This might affect the compression waves or might not. Personally I think the discharges should take place so the air flow is sequentially towards the tank, as much as possible, because I also think the important pressure waves are created by the characteristics of the check valves & pipe in the equalizer. Size, spacing, pipe diameter, and pipe taper. Elbows, fittings, and bends in the air line between the engine and tank would screw up the wave before it ever got there.
Renny, Thanks for the explanation. It is very important for multiple persons to confirm assumptions about the Neal patent, not good to depend on only a single person, mistakes can happen that way. A different point of view and different explanation style is valuable. Your firing order is identical to my earlier one, both are explained differently but are the same.
Just to be thorough, I can add that I finished with the left bank order and then the combined full compression order. As you would expect, since I arrived at the same compression order for the right bank of cylinders, my results for the full compression order are also the same as yours.
I came up with eight unique combinations. This is aside from the firing order. The firing order doesn't change, just the location they occur on the length of the crank. As Renny noted there are two possible orders for each level of pins, meaning 2 & 7, 3 & 6, 4 & 5 can be swapped, 7 with 2 etc. Two of the sequences are straight, 1 through 7 or 7 to 1.
FWIW, I was able to come up with 32 combinations, so far, but those additional 24 are the result of exploring the *theoretical* possibility that pins occupying the same level may actually be doubled up in the same position (e.g., both pins in cranks 2 & 7 being in position 7 and position 2 having no pin).