Information and animations from a technical paper presentation at the SAE Congress in Cobo Hall in Detroit on Thursday April 15th.
As scanners of this website will know, off the front page it is possible to download many of our technical papers originally published in the Race Engine Technology (RET) journal. The most recent four are authored by G.P. Blair, C.D. McCartan, and W. Melvin Cahoon. These articles are all about the design and analysis of the behaviour of all types of valve springs. Now, the same authors have published another technical paper to SAE (Society of Automotive Engineers) Annual Congress in Detroit in April where it will be presented as SAE Technical Paper 2010-01-1056. You can purchase this paper directly from SAE at the "bookstore" at www.sae.org.
The title of the paper is "Measurement and Computation of the Characteristics of Progressive Valve Springs". This paper expands significantly the measured data bank seen in the RET journal articles, indeed one of the reasons for publishing this paper at SAE is the almost complete dearth of such measured data in the (reviewed and published) technical literature.
At the SAE Congress in Cobo Hall in Detroit in April 2010, we will present this paper formally to the delegates on Thursday, April 15 in Room O2-38 at 0830 am. While, for copyright reasons, we cannot let you download the paper, we can show you here, and let you download from here, the 'mpg movies' we will use during the presentation as they are not an integral part of the technical paper.
The MPEGs show the on-screen design computation of the valve spring characteristics The 'complete' model to the left and at the centre shows the application of force increments causing spring deflection and eventually coil binding upon coil. As deflection takes place, if any element of an active coil on the complete design model binds on a dead coil then that element of the helix (at left) or (at centre) the helix centre-line is coloured 'red'. If an element on an active coil becomes bound to an element on either of its neighbouring active coils then that element of the helix element or helix centre-line is coloured 'blue'. The designer can watch live on-screen the nature and extent of the progression that has been introduced into any design. At the right is our integerised procedure which is being deflected with precisely the same force increments as the complete model. The important issue for the quality of the integerised model, which model must be used within 'valvetrain dynamics' computations, is that the correlation during a static analysis of its coil-by-coil bind, spring stiffness and natural frequency variations should correspond as closely as possible to that of the 'complete' design model.
There are five progressive springs measured and analysed in the paper. The first three are from the Yamaha 600cc R6 four-cylinder motorcycle racing engine so popular in Supersport racing and also often used in Formula SAE cars. The R6 exhaust valve spring (wound in ovate wire), the R6 intake valve (outer in round wire and the inner in ovate wire) springs are the first three springs to be used. The last two (round wire) springs are from Supermoto/Motocross racing engines and are labelled as 250std and 450 std
Here
below is the mpg (movie) of the static spring design procedure for the
Yamaha R6 exhaust valve spring (in ovate wire).
Here below is the mpg (movie) of the static spring
design procedure for the Yamaha R6 intake valve (outer) spring (in round
wire).
Here
below is the mpg (movie) of the static spring design procedure for the
Yamaha R6 intake valve (inner) spring (in ovate wire).
Here
below is the mpg (movie) of the static spring design procedure for the
250std valve spring (in round wire).
Here
below is the mpg (movie) of the static spring design procedure for the
450std valve spring (in round wire).
Here
below is the mpg (movie) of the static spring design procedure for an
example of the most complex of all valve springs (a tapered progressive
spring in ovate wire and profiled as a 'beehive'. i.e., the larger diameter
coils are the centre of the spring).
©Prof Blair & Associates