New range of Pulsar series likely to get a Variable Valve Timing mechanism in it
Gowtham•
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In the previous post only, we've clearly seen about the difference between Variable Valve Timing (VVT) and Variable Valve Lift (VVL). Manufacturers like Yamaha, BMW use Variable Valve Lift in their engine where Suzuki, Ducati use Variable Valve Timing in their engines. Now.... One of the successive auto manufacturer in India, Bajaj Auto is likely to use Variable Valve Timing in their upcoming engines and some images has been wandering throughout the internet recently. Firstly, it took me very long time to understand the concept. Let me try to explain it clearly or if you can't able to understand the concept, go through the image very deeply and surely you can able to understand the concept. Here, it seems like Bajaj has gone for Variable Valve Timing not just like Yamaha's VVA where the lift is differed. So, you don't need to confuse with that. To understand the concept clearly, you have to go through my last post.
Good step has been initiated by the Bajaj Auto by going towards this Variable Valve Timing. Simply saying, no extra cam lobes will be present for actuating the valves at higher RPMs. Instead, Bajaj has gone for simple electric motor actuator for varying the timing and this made the whole mechanism to look compact and this implementation of the electric motor neglects the need of hydraulic actuator which results in involvement of more cost to develop.
I try to explain as simple as I could. In figure 6, part number 120 is the camshaft, part number 527 is the sliding pin, part number 601 is the sliding slot and part number 225a is the sliding arm. So basically over the camshaft, cam lobes for operating the inlet and exhaust rocker arms will be present. In figure 5, part number 250a and 250b represents the cam lobes. 250a is the inlet cam lobe and 250b is the exhaust cam lobe or maybe the vice versa. The cam lobe 250a is fitted on the camshaft 120 with the help of sliding pin 527. So, when the camshaft rotates, cam lobe fixed in it with the help of sliding pin will also rotates along with it.
In figure 2, part number 115 denotes the motor actuator and part number 125 denotes the gear which is straightly geared up and connected to the part number 220 in which the sliding arm or yoke(225a) is present. So basically this acts like worm and nut. When the motor rotates, the worm arrangement present in the shaft 220 also rotates with the help of gear arrangement and moves the part number 225 that is sliding arm along with it. When it moves, the yoke in the sliding arm will also moves which slides the cam lobe in the camshaft. Here, the whole heart of the matter lies. As we know, the cam lobe is fitted in the cam shaft with the help of sliding pin which moves along the sliding slot. When yoke pushes the cam lobe, cam lobe moves along with the path of the sliding slot with the help of the sliding pin, making the cam lobe to rotate along its axis thus advance or retards the valve timing. The motor will be controlled by the ECU with gathering different information like engine speed, throttle input, camshaft position etc.. Whenever engine is running under high RPM, this motor will be actuated thus varying the valve timing for better efficiency.
Generally, Variable Valve Timing improves the overall performance of the vehicle, improves the mileage and reduces the emission. Its good to see the Indian manufacturer to implement VVT in their motorbikes and this'll become a great advantage for them to attract more customers as well as adding value for their motorbikes.
