I took apart the VVT gear on my Corolla to see how it works. I made a video of the breakdown and explanation:
Varying the valve timing on a camshaft will decrease emissions at lower engine RPM, and provide more power at higher RPM. Here’s a quick overview of the breakdown
The engine head houses the intake and exhaust camshafts at the top, in a dual overhead cam engine. The camshafts have a sprocket that links them to the crank at the bottom.
Here’s a closeup of the variable camshaft timing gear:
The camshaft gear is held on by 4 pentagon bolts. I used vice grips to get them off:
Here you can see 4 pockets that fill up with oil. The input is the gear housing (external ring) while the output is the center part.
Once removed from the gear, you can see the two input and output components inside each other. There’s a lock pin to lock the gear together when the timing hasn’t been advanced.
Taken apart, the VVT gear is pretty straight forward, the internal piece rotates along the external ring to about 15 deg. There are little plastic sliders with springs on them to help with friction.
The VVT gear is controlled through the computer by the oil control valve.
The OCV sits inside the engine head, and takes oil from the passages drilled inside the head. Depending on if the VVT is active or releasing, it redirects oil.
Back on the camshaft, you can see where the oil enters to go toward filling the gear.
Finally, when oil exits the gear, it releases along the back side of the VVT gear and drips down the timing case to the sump to be reflowed again by the oil pump.
References
https://jalopnik.com/how-variable-valve-timing-works-500056093
http://micra-forum.com/showthread.p...able-valve-timing-(CVTC)-on-Micra-1-6L-HR16DE
Enjoy!
Varying the valve timing on a camshaft will decrease emissions at lower engine RPM, and provide more power at higher RPM. Here’s a quick overview of the breakdown
The engine head houses the intake and exhaust camshafts at the top, in a dual overhead cam engine. The camshafts have a sprocket that links them to the crank at the bottom.
Here’s a closeup of the variable camshaft timing gear:
The camshaft gear is held on by 4 pentagon bolts. I used vice grips to get them off:
Here you can see 4 pockets that fill up with oil. The input is the gear housing (external ring) while the output is the center part.
Once removed from the gear, you can see the two input and output components inside each other. There’s a lock pin to lock the gear together when the timing hasn’t been advanced.
Taken apart, the VVT gear is pretty straight forward, the internal piece rotates along the external ring to about 15 deg. There are little plastic sliders with springs on them to help with friction.
The VVT gear is controlled through the computer by the oil control valve.
The OCV sits inside the engine head, and takes oil from the passages drilled inside the head. Depending on if the VVT is active or releasing, it redirects oil.
Back on the camshaft, you can see where the oil enters to go toward filling the gear.
Finally, when oil exits the gear, it releases along the back side of the VVT gear and drips down the timing case to the sump to be reflowed again by the oil pump.
References
https://jalopnik.com/how-variable-valve-timing-works-500056093
http://micra-forum.com/showthread.p...able-valve-timing-(CVTC)-on-Micra-1-6L-HR16DE
Enjoy!
