Method for operating an oil supply and controller

Abstract

A method is provided for operating an oil supply for a combustion engine and / or a transmission system of a motor vehicle particularly with start / stop-automatic, comprises the steps, that a deceleration of the motor vehicle is detected, at least one status parameter, which correlates with the manner of the deceleration, is monitored, a future oil pressure of the oil supply is estimated based on the status parameter and the actual oil supply control strategy, and if the estimated future oil pressure is below a predetermined threshold of the oil pressure, an oil pump for filling an accumulator tank of the oil supply is activated. Since the accumulator tank is filled in advance of a possible automatic stop a sufficient high oil pressure, when the combustion engine is started again, is safeguarded, wherein the period of time for accomplishing the automatic stop is not lengthened. This leads to a reduction of the fuel consumption and the CO2-emissions of the combustion engine without dealing with a too low oil pressure at the start of the combustion engine.

Description

CROSS-REFERENCE TO RELATED APPLICATIONThis application claims priority to British Patent Application No. 0914479.1, filed Aug. 19, 2009, which is incorporated herein by reference in its entirety.TECHNICAL FIELDThe technical field relates to a method for operating an oil supply for a combustion engine and / or a transmission system of a motor vehicle as well as a corresponding controller, by means of which the oil pressure of the oil supply system can be controlled.BACKGROUNDFrom DE 100 41 789 A1 it is known to override the command for an automatic stop of a combustion engine with start / stop-automatic at low oil pressure, so that an oil pump can fill an accumulator tank first before the combustion engine is stopped due to the present automatic stop command. Due to the override a sufficient oil pressure can be provided, when the combustion engine starts.It is a disadvantage of such kind of a method that the fuel consumption and the CO2-emissions of the combustion engine are high.It is a...

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Benefits of technology

This result is realized by turning away from the actual oil supply control strategy for a short period of time for filling the accumulator tank in addition to the actual oil supply control strategy. The decision to change the actual oil supply control strategy can be based on a very low number of monitored values like amount of the deceleration and / or amount of the vehicle speed, this means the speed of the motor vehicle, without significant problems. Further it is used the insight that the automatic stop will only occur after a deceleration and not after an acceleration of the motor vehicle. Thus, it is possible to trigger the start of the method, when specific conditions particularly with respect to the amount of the deceleration and / or the vehicle speed are met. For instance the method is initiated when the speed of the motor vehicle is below a particularly amount, like 20 km / h and the amount of deceleration is above zero, that means a negative acceleration of the motor vehicle is present. Particularly the status parameters can be provided via a CAN-bus, so that additional sensors are not necessary. In the case that a stop of the combustion engine did not occur as estimated no drawbacks are present. The regular standard oil supply control strategy can deal with the filled accumulator tank without problems.

The predetermined threshold of the oil pressure is particularly chosen such that, when the combustion engine starts, an operation of the oil pump is not necessary for a particular period of time. Particularly the accumulator tank is filled for providing an oil pressure significantly above the threshold for providing a safety reserve and / or considering an increasing deceleration over the period of time until the stop of the motor vehicle as calculated prior. The required oil pressure for this period of time can be provided by the level of oil in the accumulator tank only. For starting the combustion engine an automotive battery does not have to provide electric energy to the oil pump during the engine crank event. The respective electric energy is saved for starting the combustion engine. After the start of the combustion engine the necessary electric energy can be provided by an electric generator driven by the combustion engine. The charge of the automotive battery can be saved. The method can be applied to conventional pure combustion engine motor vehicles, when the automatic stop of the start / stop-automatic is used for stopping the combustion engine automatically at a stop of the motor vehicle with zero vehicle speed. The method can be further applied to a hybrid motor vehicle, when the automatic stop of the start / stop-automatic is used for changing from combustion engine mode to electric machine mode.

A controller is also provided according to an embodiment of the invention for carrying out the method as previously described, wherein the controller comprises at least one sensor for detecting a deceleration of the motor vehicle and / or at least one status parameter, which correlates with the manner of the deceleration, a data input for connection to an oil supply controller, a calculation unit for estimating a future oil pressure of the oil supply based on the status parameter and the actual oil supply control strategy, and an activator output connected to an oil pump for filling an accumulator tank of the oil supply, if the estimated future oil pressure is below a predetermined threshold of the oil pressure. The oil supply controller can provide the usual standard oil supply control strategy for the oil supply system. Due to the data input internal variables of the oil supply controller can be used by the controller according to the invention. The sensor for detecting a deceleration can use the vehicle speed as status parameter so that for instance two measured vehicle speed at two different points of time can be compared for detecting, whether a deceleration is present. The activator output can be a switch for turning on or off the oil pump. The activator output is particularly in parallel to the oil supply controller connected to the oil pump, so that the activation of the oil pump based on the control of the oil supply controller and based on the control of the controller according to the invention can be superposed. Since the accumulator tank is filled in advance of a possible automatic stop a sufficient high oil pressure, when the combustion engine is started again, is safeguarded, wherein the period of time for accomplishing the automatic stop is not lengthened. The period of time until the automatic stop is initiated after a stop of the motor vehicle can even be shortened. This leads to a reduction of the fuel consumption and the CO2-emissions of the combustion engine without dealing with a too low oil pressure at the start of the combustion engine.

The embodiments of the invention further relate to an oil supply system for a combustion engine and / or a transmission system of a motor vehicle particularly with start / stop-automatic, wherein the oil supply system comprises an oil circuit for providing oil to the combustion engine, an oil pump for pumping oil through the oil circuit, an accumulator tank for storing oil and providing an oil pressure, wherein the accumulator tank is connected to the oil pump for filling the accumulator tank, and a controller, which can be designed as previously described, connected to the oil pump for carrying out the method as previously described. Since the accumulator tank is filled in advance of a possible automatic stop a sufficient high oil pressure, when the combustion engine is started again, is safeguarded, wherein the period of time for accomplishing the automatic stop is not lengthened. The period of time until the automatic stop is initiated after a stop of the motor vehicle can even be shortened. This leads to a reduction of the fuel consumption and the CO2-emissions of the combustion engine without dealing with a too low oil pressure at the start of the combustion engine.

Problems solved by technology

It is a disadvantage of such kind of a method that the fuel consumption and the CO2-emissions of the combustion engine are high.

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