The objective of this paper is to indicate the design principals of a Continuously Variable Transmission that is physically about the size of a conventional manual transmission for the same power and torque with an equal or better efficiency and durability. The CVT will be designed for use in either a hybrid electric drive or a conventional vehicle with the addition of a torque converter and reverse gear. The design objectives are as follows:
1. About the same size as a 5 or 6 speed manual transmission for North-South engine orientation and rear wheel drive. 2. About the same weight as the 5 or 6 speed manual transmission 3. Cost about the same or less 4. Much smaller than a comparable performance rated automatic transmission 5. Fewer parts than manual transmissions and less than 1/30th of the part count of an automatic. 6. Ratio span greater than equivalent manual or automatic transmissions. 7. Adaptable up to Class 8 trucks to replace 18 speed manual transmissions with 2000NM and 500kw capacity. 8. Higher efficiency and quieter than a manual transmission. 9. Durability equal to or greater than a manual transmission. 10. Very low noise. 11. Complete flexibility in control using computer controllers for fully automatic to manual ratio control for cars and trucks.
The paper will discuss the specific design philosophy of a 500 NM, 250 kw CVT for a SUV and truck application and it’s installation. The prototype is designed for volume production by minimizing the number of parts. The total number of parts for this completely automatic transmission will be about 12 including all bearings. We will focus on the In-line CVT design for the front engine rear wheel drive cars with the design of this paper, but for front wheel drive vehicles a single stage CVT design will generally be the preferred.
A discussion of the low cost high accuracy and low power control system used in this transmission will be provided. The geometry used shows the simplicity and flexibility of the design to satisfy a wide range of applications. The components used for the design will be discussed. The following Figure 1, shows the proposed concept. This concept is expected to be installed in a Ford Explorer for demonstration at the CVT-hybrid2004 Congress. It replaces a 5 or 6 speed manual transmission.