Heavy/light traffic based on vehicle speeds and throttle positions

Claim 1

A transmission control unit for an automatic transmission for controlling the automatic transmission in accordance with one of a heavy traffic control scheme and a light traffic control scheme, said control unit comprising: sensor means for detecting parameters representative of vehicle conditions including at least vehicle and throttle opening, traffic condition determination means for classifying traffic as heavy or light, based on the parameters as detected by said sensor means, said traffic condition determination means including: speed zone classification means for defining a plurality of vehicle speed zones, each of said zones extending over a range of vehicle speed values spanning a predetermined speed differential, said speed zones including a plurality of low speed zones, a plurality of high speed zones and a boundary dividing said low speed zones from said high speed zones, said speed zone classification means providing a predetermined control value for each of said plurality of vehicle speed zones, said predetermined control values being such that the difference between said predetermined control values for adjacent zones increases with increasing proximity to said boundary, said predetermined control values being positive for said low speed zones and negative for said high speed zones, speed flag setting means for setting a vehicle speed value and for matching said vehicle speed detected by said sensor means to the one of said vehicle speed zones containing the detected speed, the predetermined control value for said one vehicle speed zone being added to said vehicle speed value to reset the vehicle speed value, the traffic being classified as heavy if said reset vehicle speed value exceeds a preset value and being classified as light if said reset vehicle speed value is less than said preset value, and transmission pattern selective means for selecting one of a normal traffic transmission map and a heavy traffic transmission map in response to traffic classification determined by said traffic condition determination means, and transmission control means for changing gear ratios according to the selected transmission map.