HYDRAULIC ACCUMULATOR TEMPERATURE ESTIMATION FOR CONTROLLING AUTOMATIC ENGINE STOP/START
A method of preventing an automatic engine stop includes estimating a temperature of a volume of fluid within a hydraulic accumulator that is in selective fluid communication with a fluidly-actuated torque-transmitting device. The torque-transmitting device is coupled to an internal combustion engine and configured to selectively transmit a torque from the engine to a vehicle wheel. The method further includes comparing the estimated fluid temperature to a temperature range, and preventing the internal combustion engine from automatically stopping if the estimated fluid temperature is outside of the temperature range.
1 . A method of preventing an automatic engine stop comprising:
estimating a temperature of a volume of fluid within a hydraulic accumulator, wherein the hydraulic accumulator is in selective fluid communication with a fluidly-actuated torque-transmitting device coupled to an internal combustion engine;
comparing the estimated fluid temperature to a temperature range; and
preventing the internal combustion engine from automatically stopping if the estimated fluid temperature is outside of the temperature range.
2 . The method of claim 1 , wherein estimating a temperature of the volume of fluid includes:
computing a first temperature change of the volume of fluid that is attributable to heat transfer from the volume of fluid to a surrounding environment.
3 . The method of claim 2 , further comprising introducing fluid from a hydraulic circuit into the volume of fluid; and
wherein estimating a temperature of the volume of fluid further includes computing a second temperature change in the volume of fluid that is attributable to fluid mixing with the introduced fluid.
4 . The method of claim 1 , further comprising discharging the volume of fluid within the hydraulic accumulator if the estimated fluid temperature is outside of the temperature range.
5 . A vehicle comprising:
an internal combustion engine configured to combust a fuel to provide a mechanical rotary output, and automatically stop combusting the fuel if vehicle motion is prevented by a braking device;
a transmission coupled with the internal combustion engine and including a fluidly actuated torque transmitting device configured to selectively transmit the rotary output of the internal combustion engine to a vehicle wheel;
a hydraulic control system in fluid communication with the torque transmitting device, the hydraulic control system including a fluid circuit in fluid communication with a fluid sump and a hydraulic accumulator, wherein the hydraulic accumulator is configured to selectively retain a volume of fluid;
a control module in communication with the hydraulic control system and with the internal combustion engine, the control module configured to:
estimate a temperature of the volume of fluid within a hydraulic accumulator;
compare the estimated fluid temperature to a temperature range; and
prevent the internal combustion engine from automatically stopping if the estimated fluid temperature is outside of the temperature range.
6 . The vehicle of claim 5 , wherein the control module is configured to estimate a temperature of the volume of fluid by computing a first temperature change of the volume of fluid that is attributable to heat transfer from the volume of fluid to a surrounding environment.
7 . The vehicle of claim 6 , wherein a fluid is configured to flow from the fluid circuit into the hydraulic accumulator and mix with the volume of fluid; and
wherein the control module is configured to estimate a temperature of the volume of fluid by computing a second temperature change in the volume of fluid that is attributable to fluid mixing with the introduced fluid.
8 . The vehicle of claim 5 , wherein the control module is configured to discharge the volume of fluid within the hydraulic accumulator if the estimated fluid temperature is outside of the temperature range.
9 . The vehicle of claim 5 , further comprising a temperature sensor disposed within the fluid sump, and configured to monitor the temperature of a fluid within the fluid sump.
10 . A vehicle comprising:
an internal combustion engine configured to combust a fuel to provide a mechanical rotary output, and automatically stop combusting the fuel if a vehicle motion is prevented by a braking device;
a transmission coupled with the internal combustion engine and including a fluidly actuated torque transmitting device configured to selectively transmit the rotary output of the internal combustion engine to a vehicle wheel;
a hydraulic control system in fluid communication with the torque transmitting device, the hydraulic control system including a fluid circuit in fluid communication with a fluid sump and a hydraulic accumulator, wherein the hydraulic accumulator is configured to selectively retain a volume of fluid;
a control module in communication with the hydraulic control system and with the internal combustion engine, the control module configured to:
maintain an estimate of a temperature of the volume of fluid within the hydraulic accumulator;
estimate a change in the temperature of the volume of fluid within a hydraulic accumulator using the estimate of a temperature of the volume of fluid, an ambient temperature, and a temperature of a fluid within the fluid sump;
update the estimate of temperature of the volume of fluid with the estimated change in temperature;
compare the updated estimated fluid temperature to a temperature range; and
prevent the internal combustion engine from automatically stopping if the estimated fluid temperature is outside of the temperature range.
11 . The vehicle of claim 10 , wherein the control module is configured to estimate the change in the temperature of the volume of fluid by computing a first temperature change of the volume of fluid that is attributable to heat transfer from the volume of fluid to a surrounding environment.
12 . The vehicle of claim 11 , wherein a fluid is configured to flow from the fluid sump into the hydraulic accumulator and mix with the volume of fluid; and
wherein the control module is configured to estimate a temperature of the volume of fluid by computing a second temperature change in the volume of fluid that is attributable to fluid mixing with the introduced fluid.
13 . The vehicle of claim 10 , wherein the control module is configured to discharge the volume of fluid within the hydraulic accumulator if the updated estimate of fluid temperature is below the temperature range.
14 . The vehicle of claim 10 , further comprising a temperature sensor disposed within the fluid sump, and configured to monitor the temperature of a fluid within the fluid sump.