Back again...

I have learned the hard way to always back up your important files. A few months ago I accidentally spilled water on my laptop and destroyed it. I lost everything that I was working on and, out of frustration, decided to put this entire project on hold. That was then but now I have a new laptop and it was only a matter of time before I began tinkering with designs again.

I was reading through this blog before posting this and realized that a fresh start may not be such a bad idea. Instead of trying to design any major components, I will solve the problem of valve actuators and position sensors first. Once I have a viable solution, then my focus will shift to intake/exhaust ports, combustion chambers, and piston design. I will worry about what comes after that once the time arrives.

I have been doing some research and found a GM patent that I thought was very interesting. Click here to check it out.

New ideas

Sometimes when you have a problem the best thing you can do is walk away from it. Well I am focused on this project again and some things caught my attention the second I loaded the CAD model today. For starters I am designing the engine block around the position sensors for the valve actuators. They are entirely too big and they rely on magnets. Entirely too much fluid must be displaced to move the valve actuator to a desired position and EMI would affect position sensor accuracy. I can miniaturize the whole system and solve these problems by going with a custom made position sensor. I'm off to start sketching out the new design and rebuilding the CAD model. Here are a few shots of the block before I begin redesigning it for a third time.

Back to work

I have put the project on the back burner for a while so that I could take care of personal business. I have been going through my notes and sketches to pick up where I left off and decided to not do that. Instead of concentrating on cylinder head design I am going to finish the cylinder block. This is my way of stopping me from getting ahead of myself. I will post my progress and future plans after the holidays.

Progress so far

It has been a while since my last update. I have decided to integrate a good portion of the actuator assembly into the cylinder heads to make the engine a little more compact. Most of my time has been spent researching combustion chamber design, direct injection technology, intake and exhaust port profiles, and how to organize them efficiently in the CAD model. I will post detailed information and screenshots in the next few days.

New approach

My design goal of making this engine block compatible with a Gen I Chevy small block engine has caused more problems than expected. The biggest problem is the hydraulic actuators for the intake and exhaust valves. The integrated position sensors are too long to fit in the optimal position. Every solution to this problem I have drawn up that will allow the engine block dimensions to stay within limits has a negative impact on the actuator design. I have began drawing up a new engine block without the design goal of being SBC compatible. This will increase the number of custom designed components necessary for the physical prototype. I feel that to properly design a working prototype I need to start from the inside and work my way out, not the other way around. Here are a few screenshots of the new engine block so far.

Position sensor problems

I was doing some trial fitting after downloading CAD data for the smallest MTS linear position sensor I found at this point in time. At first I thought it would be too big but I am going to spend some time trying to tweak it into position to see if that is the case before deciding to not use this sensor. If I can make it work out, the pushrod will be a part of the actuator itself. Increasing the bore for the position sensors also created clearance problems for the caps that will seal the actuator bore. This problem can be remedied easily but I can see that this entire area will be problematic to the water jacket plates regardless. I will try contacting MTS to see if they offer a smaller sensor. If they do not, hopefully I can get this one to work.

 

Position sensors and hydraulic solenoids

I found this position sensor made by MTS last year while working the original design. I really like them because of the accuracy, response time, and durability. This is a non contact sensor so wear over time is not an issue and it is easy to calibrate and recalibrate as necessary to compensate for thermal expansion as the engine is running. MTS will actually custom make sensors for companies, but I do not have the money to pay for this luxury at this point in time. The major problem with this sensor is its size. It will require a cavity about 2 inches in diameter. I would have to move the bore centerlines which means that the push rods would be drastically angled. I thought about using an offset on the actuators to line the push rods back up with the rockers, but I am not happy with the added mass to the actuators required. Getting this system to operate at at 6000 RPM minimum is already going to be a challenge so adding weight to the reciprocating assembly is not a solution I will accept. I checked out the MTS product line again and found this position sensor. It has a diameter of 1.1 inches which I can squeeze into place by increasing the bore and adding a little material for support.

I am having doubts again about where to place the hydraulic solenoids. I am thinking about mounting them in the valley again. Having remote mounted solenoids would be ideal but that creates more problems than it solves. Having 16 separate hydraulic lines running into the engine block adds too many potential leak points, adds unnecessary clutter in the engine compartment, and complicates the way fluid is routed internally. These lines would also interfere with the accessories at the front of the engine and the bell housing at the rear.

My next major obstacle is going to be a crankshaft position sensor. Accuracy to the half degree would be perfect but, I am going to need something that is at least accurate to the degree. I have quite a bit of work to do before I really have to worry about this so I will just see what's out there for the time being.