Rod side clearance oil squirting?

[4vpc]

I think the hot rodder needs to carefully study the design and execution of the slots. Haphazard attention to detail will yield haphazard results. Below are two Honda piston and rod assemblies. In "a" the oil is aimed under the piston; in "b" it is sprayed on the cylinder walls.

honda a.jpg
honda b.jpg

Do you know if they had those on both sides?
A pic of a Mazda one here, it's got one on each side pointing at each way.
So Kevin, for 50 points; bore or piston?

2018-09-24 2.5 rod (1).jpg

Interestingly that series of engines also had piston squirters in the block, 4 pin oilers per side (of piston) and really tight bearing clearances. Yet after X amount of miles the oil control rings got gummed up, stuck together and they started using oil really heavily. The owners often never noticed so many of them ran completely out of oil and were scrapped.

[modok]

probably are both sides.
I don't recall ever seeing a notch on only one side.
Offsetting it to one side in respect to the rotation seems to be the norm, instead of dead center.

some have two notches per side, it seems like that would make it work either direction. Can't put it in wrong, always a wise design choice.

Picture reminds me of a Suzuki engine, just like the Mazda, same exact deal. They like to burn oil, thus throw rods, although, IMO the rods are very nice design.

[PackardV8]

On an inline, the slots are at the top of the rods, but some older V8s have a slot coming off the diagonal.

[modok]

Hmm, perhaps aiming for the camshaft.

What I don't get is why subaru didn't put the notches in the cap. it's a flat four..... the cap nearly touches the opposite piston at BDC

[Kevin Johnson]

You need to look more closely at the slots themselves. One set has straight boundary walls and the other curved. If you are viewing them on a cell phone you will need to expand/magnify the image.

Both slots are too short and have too much area to produce anything else other than a general oil spraying mess, I think.

No, I was wrong!

I found Honda's patent. Argue with them at length if you wish.

Piston oil-cooling device in an engine
...
In the vertical engine as described above, the cooling oil injection grooves 73, 73 in each of the connecting rods 28 are provided in the lower side thrust face 70 of the larger end 28 b of the connecting rod 28. Thus, the opposed side thrust faces 70 and 75 of the larger end 28 b and the crankshaft 5 are in closed contact with each other under the weight of the connecting rod 28. Therefore, it is possible to inhibit the leakage of the cooling oil from the cooling oil injection grooves 73, 73 in the connecting rod 28 between both side thrust faces 70 and 75 to maintain the force of the oil injected from the cooling oil injection grooves 73, 73. Moreover, it is possible to ensure that the oil injected from the cooling oil injection grooves 73, 73 easily reaches the corresponding piston 27 without being obstructed by the connecting rod 28. As a result, the piston 27 can effectively be further cooled.

The side thrust face 75 of the crankshaft 5 opposed to the side thrust face 70 of the larger end 28 b of each connecting rod 28 is formed to cover the entire open surfaces of the cooling oil injection grooves 73, 73. Thus, the open surfaces of the cooling oil injection grooves 73, 73 in the larger end 28 b of the connecting rod 28 are closed by the side thrust faces 75 of the crankshaft 5. Thus, wasteful leakage of the cooling oil from the open surfaces of the cooling oil injection grooves 73, 73 is prevented to maintain the force of the oil injected from the cooling oil injection grooves 73, 73, thereby more effectively cooling the piston 27.
...
Although the preferred embodiment of the present invention has been described above in detail, it will be understood that the present invention is not limited to the above-described embodiment, and various modifications in design may be made without departing from the subject matter of the invention. For example, the engine E may be formed into a horizontal type with its crankshaft disposed horizontally, or into a single-cylinder type.

Figure_9a_b.jpg

[ptuomov]

No patent lawyer is going to get the oil to fly in a narrow cone and fast enough not to be dominated by rod/crank g forces out of the rods slots in the photos.

[Kevin Johnson]

No patent lawyer is going to get the oil to fly in a narrow cone and fast enough not to be dominated by rod/crank g forces out of the rods slots in the photos.

Honda has some very talented lawyers on staff:

https://patents.google.com/?inventor=No ... uki)+Honda


https://patents.google.com/?inventor=Mi ... aka)+Honda


https://patents.google.com/?inventor=Hi ... ida)+Honda

[4vpc]

it seems like that would make it work either direction. Can't put it in wrong, always a wise design choice.

A lot of modern stuff is like that, it's because it's robot built. Valve guides now are the same at both ends, I suspect they're fed into some machine a bit like bullets into a machine gun and it just forces them in no matter which way they end up.

[ptuomov]

Those wide slots are useful in directing the oil from the rod bearings either generally up or generally down in a four banger engine. The slots are so wide and short and the oil pressure is relatively low at that point that the oil will fly out following the tangent of the orbit when that tangent is less than 90 degrees from the openings face. This sets up a pattern where the oil flies out for about 180 degrees of the orbit, not exactly 180 degrees because the rod angle changes somewhat. Then, the oil spray gets pushed around by crankcase piston pumping pulses and it ends up mostly on the bore walls. Some will touch the piston, of course, but the volume flowing to the pistons is not going to be in sufficient volume to move the needle for piston cooling, I think.

Someone mentioned the boxer engine. Boxer engine has one bore wall oiling issue that these slots could help. One of the banks has the major thrust face on the upper half of the crankcase. Because of the gravity, this upper side tends run drier than the lower side. On the side where the major thrust side is on the upper half of the case, there’s also a lot of load. Slotting the rod to direct oil in the general vicinity of that upper thrust face sounds like a good idea.

[Kevin Johnson]

... In particular, in the pair of cooling oil injection grooves 73 and 73 that are close to the corresponding lubricating oil holes 62 and 63, since the decrease in the momentum of the oil is small, a relatively large amount of oil is ejected vigorously therefrom. It is possible to reliably reach the back side of the corresponding piston 27 and cool it effectively.

Honda used dedicated squirters on some engines using the grooves but not on others. This indicates they were monitoring the piston temperatures and if additional cooling flow was required, they provided it.

[ptuomov]

Honda used dedicated squirters on some engines using the grooves but not on others. This indicates they were monitoring the piston temperatures and if additional cooling flow was required, they provided it.

Of course they consider the piston cooling requirements in their designs and add piston oil cooling jets if the heat flow calculations say they are needed. I think the slots on the rods are largely unrelated to this, however, patent claims aside. Much more likely, the slots on the rod are added when they think more oil is needed on the bore walls. For oil to cool a piston, a sufficient oil flow has to actually hit the piston, and for that once needs a lot of velocity and a narrow spray pattern -- something that those rod side slots can't provide.

[Kevin Johnson]

I guess it comes down to you having an opinion about that and their engineers stating the contrary in a patent. People can make up their own minds.

[ptuomov]

I guess it comes down to you having an opinion about that and their engineers stating the contrary in a patent. People can make up their own minds.

That's right, think thru the physics, read what was written, and make up your mind.

[Kevin Johnson]

I guess it comes down to you having an opinion about that and their engineers stating the contrary in a patent. People can make up their own minds.

That's right, think thru the physics, read what was written, and make up your mind.

Yes, and I would add that slotted connecting rods date back to splash oiling systems (100 years plus) and that all manner of configurations are/were used. As the original engineers pass away the institutional knowledge of oiling distribution patterns becomes more and more mysterious apparently.

The 1937 video below shows that stroboscopic cameras were being used by OEMs to study oil droplet distribution patterns; in this case at 3600rpm:

[Roy]

I think everyone may be missing a key point, the connecting rod is only in-line with the piston at TDC, besides that the connecting rod is angled... What I am getting at is that the oil channels would effectively act like a sprinkler as it goes through a rotation, spraying the inboard wall, piston, then outboard wall...I would think anyway.