US 5,707,315 A · Control system for hydraulically operated vehicle transmission

Abstract

A vehicle automatic transmission control system which makes it possible to estimate an ATF temperature without using an expensive ATF temperature sensor. The estimation of the ATF temperature is configured such that based on the coolant temperature at engine starting, the temperature increase owing to heat inflow to the ATF per unit time and the temperature decrease owing to heat outflow from the ATF per unit time are calculated quantitatively and the sum of the calculated values is used to determine the estimated ATF temperature TATF. More specifically, when it is found that only a short time has passed between engine turnoff and restarting, the ATF temperature is estimated at engine restarting from the coolant temperature at engine turnoff, the estimated ATF temperature at engine turnoff and the coolant temperature at engine restarting. On the other hand, when the time between engine turnoff and restarting is found to be long, both the coolant and the ATF are assumed to be completely cooled and the ATF temperature is in principle defined as the coolant temperature at restarting.

Claims9

Dependent claims

A system for controlling a vehicle transmission operated by pressurized hydraulic fluid having an input connected to an internal combustion engine mounted on the vehicle which is cooled by a cooling medium, and an output connected to vehicle wheels, comprising:

first temperature detecting means for detecting a first temperature of the cooling medium at a turnoff of the engine;
second temperature detecting means for detecting a second temperature of the cooling medium at a restarting of the engine after the engine turnoff;
comparing means for comparing the first temperature and the second temperature;
fluid temperature estimating means for estimating a temperature of the fluid of the transmission at the engine restarting based on a result of the comparison;
and
transmission fluid pressure control means for controlling pressure of the fluid of the transmission as a function of the estimated temperature of the fluid of the transmission.

3 more elements

vehicle operating condition detecting means for detecting operating conditions;
first temperature detecting means for detecting a first temperature of the cooling medium at a turnoff of the engine;
second temperature detecting means for detecting a second temperature of the cooling medium at a restarting of the engine after the engine turnoff;
comparing means for comparing the first temperature and the second temperature;
first fluid temperature estimating means for estimating a fluid temperature based on the operating condition of the vehicle up to the turnoff of the engine;
second fluid temperature estimating means for estimating a fluid temperature at the engine restarting based on a result of the comparison and the temperature estimated by the first estimating means;
and
transmission fluid pressure control means for controlling the pressure of the fluid of the transmission as a function of the estimated fluid temperature estimated by said second fluid temperature estimating means.

5 more elements

Dependencies are inferred from the claim text.

Control system for hydraulically operated vehicle transmission

Life of this patent

Control system for hydraulically operated vehicle transmission

Life of this patent

Abstract

Claims9