Variable compression rate helical spring - has wire of gradually changing cross section varying from square at ends to round at centre

摘要

The helical springs described are useful in vehicle suspension systems where a low spring stiffness is required with light loads progressively increasing as the load increases. To achieve this, the spring wire is made with a section varying gradually (2,3) from square (4,5) at the ends to round (1) in the middle. With a spring of this form, the outer coils are weaker and as the spring is compressed, progressively lie against each other. The construction also ensures a light weight spring which can have a short length when compressed. Variants with smaller diameter coils at the ends than the middle are given and the compression law can be tailored as required. Machines for rolling the wire cross-section from circular to square and for winding the springs are also described.