US 5,921,883 A · System for managing engine retarding torque during coast mode operation

Abstract

A system for managing engine retarding torque during coast mode operation includes a control computer operable in one embodiment to control boost pressure, engine compression brake setting and/or engine accessory deactivation upon detection of coast mode operation with the engine compression brakes enabled. In another embodiment, the control computer is operable to determine a current engine retarding torque value, based either on an estimation thereof as a function of current boost pressure and engine compression brake setting or based on a mass estimation technique accounting for the grade of the road, and control boost pressure, engine compression brake operation and/or engine accessory deactivation to thereby control engine retarding torque upon detection of coast mode operation with the engine brakes enabled. In either case, the control system is operable to manage engine retarding torque so as not to exceed the coast mode torque capacities of any of the drivetrain components, and of the axle assembly in particular.

Claims12

Dependent claims

A method of controlling retarding torque of an internal combustion engine equipped with engine compression brakes and carried by a vehicle, the method comprising the steps of:

determining whether the vehicle is undergoing coast mode operation;
determining whether engine compression brake operation is enabled;
determining one of a currently engaged gear ratio and vehicle speed;
determining a coast mode torque capacity of a drive axle carried by the vehicle;
and
controlling retarding torque of the engine as a function of said one of a currently engaged gear ratio and vehicle speed only if the vehicle is undergoing coast mode operation and engine compression brake operation is enabled, thereby maintaining the retarding torque of the engine below the coast mode torque capacity of the drive axle.

3 more elements

A system for controlling retarding torque of an internal combustion engine coupled to a transmission, comprising:

an engine compression brake control unit producing a number of engine compression brake request signals and an engine compression brake enabled signal when enabled for operation;
an engine brake system associated with the engine and producing an engine retarding torque in response to at least one engine compression brake control signal;
means for producing a coast mode signal when the vehicle is coasting;
a drivetrain component having a coast mode torque capacity limit associated therewith;
means for determining a currently engaged transmission gear ratio;
means for sensing vehicle speed and producing a vehicle speed signal corresponding thereto;
and
a control computer responsive to said engine compression brake enabled signal and said coast mode signal to control engine retarding torque as a function of one of said gear ratio and said vehicle speed signal, thereby maintaining the engine retarding torque below said coast down torque capacity limit of said drivetrain component.

5 more elements

Dependencies are inferred from the claim text.

System for managing engine retarding torque during coast mode operation

Life of this patent

System for managing engine retarding torque during coast mode operation

Life of this patent

Abstract

Claims12