Necessity of Throttle Valve
Necessity of Throttle Valve
(OP)
I've been lately doing some research as to whether or not the throttle valve will be a component in future generations of direct injection petrol engines. Theoretically in the fully variable valve drive motor systems (BMW's Valvetronic motor for instance) it is not really necessary, yet to my knowledge it is still being incorporated.
Could this be because the throttle valve must fulfill secondary functions, (vacuum for brake cylinder, carbon filter regeneration for the fuel tank, exhaust gas recycling)?
Could this be because the throttle valve must fulfill secondary functions, (vacuum for brake cylinder, carbon filter regeneration for the fuel tank, exhaust gas recycling)?





RE: Necessity of Throttle Valve
RE: Necessity of Throttle Valve
Maybe there is a problem controlling the valve train to the required degree of accuracy.
Maybe there is more mass to move to control the valve train, therefore maybe the response rate is to slow to maintain a stable idle under various loads from ancillaries.
Maybe it is as you say, to provide a vacuum source.
Regards
pat
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RE: Necessity of Throttle Valve
valve(s) instead. Just something else to cost a motorist more money to fix when something goes wrong. Kinda like the set prices on O2 sensers. $90.00 everyplace you go.
RE: Necessity of Throttle Valve
A motor without a throttle valve must of course have direct injection.
I thought that one of the main benefits of variable valve motor systems was the absence of throttling at the low end part of the load cycle, thereby avoiding the resulting pressure and efficiency loses. It would seem that the motor manufacturers for whatever reason have not achieved this goal yet. If this is the reason I would assume that they are working on a solution. And then the days of the throttle valve are numbered.
As far as generating vacuum is concerned, it seems to me that the throttling of the engine for this purpose is a pretty inefficient way to go about it. A vacuum pump would seem like an better solution, unless you would need a number of them, in which case it may not be cost effective.
Regards
RE: Necessity of Throttle Valve
http://carambola.usc.edu/Research/TPCE/TPCE.html
Intake air heating + lean burn + CNG or LPG fuel
RE: Necessity of Throttle Valve
To maintain accuracy and patern, very small injectors might prove necessary. This might make secondary (large) injectors necessary for full power and/or high speed.
To help minimise cost increases, less than one injector per cyl could be used if placed in the plenumb area, with cyl to cyl trimming done by the idle injectors, or with one secondary injector per cyl, and only half the cylinders operating at idle. This would double the air and fuel requirements on the few cylinders being used at idle.
Sorry for the ramble.
Regards
pat
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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.