A Unique Methodology to Improve the Clutch Pedal Characteristics of a Compact Sports Utility vehicle

Clutch characteristics play a vital role in ensuring a smooth and comfortable customer experience of any vehicle. The expectation is to have an optimized clutch pedal effort, reduced pedal travel, adequate modulation zone and a smooth and quick pedal returnability. However, achieving all these customer requirements is extremely challenging in some cases. In the present work, the authors discuss on improving the clutch pedal characteristics of a compact sports utility vehicle (SUV by adapting a unique approach of combining a dual torsion spring (DTS) and a return spring (RS). DTS is widely used in the clutch pedal to improve the pre-load at zero travel (1.5 kg to 2.0 kg) to improve the pedal returnability in the free-play zone. Moreover, it is also quite helpful to reduce the peak pedal effort by giving a positive assistance. However, the introduction of DTS would also bring down the pedal effort (pedal holding force) at the end of the travel affecting the pedal returnability at the stay-out position. Moreover, the reduction in clutch release loads at the rated engine speeds (5500 rpm) could further deteriorate the returnability. The issue is even more predominant in gasoline engines operating at a higher rated speed. Reducing the travel ratio of the clutch pedal might resolve the returnability issue, however, it would lead to a reduction in the modulation zone leading to an uncomfortable and uncontrolled launch behaviour. Thus, a unique method of combining a DTS and RS was investigated to address the concern of pedal returnability observed at high engine operating speeds. The paper explains the methodology followed in a simple and sequential manner with all the relevant measurement data