Shift System Inertia Mass Optimization Techniques to Minimize Double Bump for Manual Transmission

The demand of gear shift quality in vehicles has increased considerably in the past few years. The gear shift is the key interface between driver and vehicle transmission. The essential criterions for the operating quality of the gear shift is the operating force and feel on the gear shift knob at each stage of gear shift, starting from start of gear shift to the end of gear shift. This paper deals with techniques to reduce secondary force due to synchronizer sleeve hitting on dog ring at the end of gear shift which is also known as Double Bump. The double bump ratio should be less than 0.4 to achieve the best in class shift feel for passenger car segment. Normal driver will not feel if double bump ratio is less than 0.6. Inertia mass mounted on shift system of manual transmission helps to generate momentum at the end of gear shift to nullify the double bump force.

An iterative technique is established to increase the shift mass inertia on shift system and objective data measurement using Gear Shift Quality Assessment (here after referred as GSQA) instrument to optimize the inertia of shift mass for achieving best in class double bump ratio target for inline transmission as well as transaxle with minor add/delete of mass on shift system.