Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site watdaisy.UUCP Path: utzoo!watmath!watdaisy!gvcormack From: gvcormack@watdaisy.UUCP (Gordon V. Cormack) Newsgroups: net.auto Subject: Camless valve operation Message-ID: <6848@watdaisy.UUCP> Date: Tue, 8-Jan-85 10:26:00 EST Article-I.D.: watdaisy.6848 Posted: Tue Jan 8 10:26:00 1985 Date-Received: Wed, 9-Jan-85 02:13:44 EST Distribution: net Organization: U of Waterloo, Ontario Lines: 29 It has been suggested that the valves in an engine be operated electrically rather than by a cam. There is no doubt that such operation could give more nearly optimal valve operation than a fixed cam. The above scheme has been implemented for the purposes of engine testing (I can't remember the reference, it was either PM or C&D or R&T in the last 10 years). The trouble is that the solenoids to operate the valves are tremendously inefficient and consume a significant fraction of the overall output from the engine. On a test bench, this is not a problem. In addition, the electronics must switch a tremendous amount of current to operate the solenoids quickly. Such switches are not cheap. The alternator, battery, etc. on existing cars would also be totally inadequate. If someone could invent an efficient mechanism to control the valves like this, he would indeed have a better mousetrap. I suggest the following compromise: (perhaps it has been investigated, too) use a twin-cam engine where the valve is open if either of the cam lobes is up (the valve operation is the OR of the two cams). Statically, both cams are the same. At increased engine speed, one of the cams is advanced and the other retarded as necessary to get the desired overlap. The device to advance and retard the cams should be feasible as it operates at a much lower speed than that described above. It could be implemented in much the same way as existing hydraulic timing chain tensioners. It is not clear that the extra mechanical complexity is justified, but such a device would give a factor of 2 in adjustment of the valve durations.