Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
1997-08-13
2001-06-05
Louis-Jacques, Jacques H. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S055000, C701S069000, C701S066000, C477S109000, C477S110000
Reexamination Certificate
active
06243636
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to a method of controlling a change in a torque value of a semi-automated vehicle transmission system using a two-stage process.
Vehicle transmissions are well known and include automatic, manual and semi-automatic types. Each of the transmission types have advantages that make them suitable for various applications. Heavy duty vehicles typically include a manual or, more recently, a semi-automatic transmission. Semi-automatic transmissions of various types have been proposed. The basic principal is to assist a driver in performing a manually selected gear ratio change using a system that is at least partially automated. While such transmissions have advantages, they are not without shortcomings and drawbacks.
For example, in a partially automated transmission at some point during a gear ratio change, the driver is precluded from controlling the engine and transmission. The transition from automated control back to driver control is often accompanied by less than desirable phenomena. For example, a change in torque value when returning control to the driver can result in wheel slip or a relatively abrupt change in vehicle wheel speed. Both of these conditions are potentially annoying or distracting to a driver of the vehicle and introduce potential undue wear on the transmission.
Therefore, it is desirable to provide a method of controlling torque changes in a vehicle transmission that results in a more smooth transition between operating states when returning control of the transmission and engine to the driver of the vehicle. This invention addresses those needs and provides an effective solution.
SUMMARY OF THE INVENTION
In general terms, this invention is a method of controlling a torque value in a vehicle transmission. The method of this invention is particularly useful for controlling torque values when returning control of a transmission and vehicle engine to the driver.
The inventive method includes several basic steps. Once a desired torque value is determined, a matching condition is defined where the current torque value corresponds to the desired torque value. The current torque value is then changed at a first rate of change so that it approaches the desired value. The current torque value is progressively changed at the first rate until the matching condition exists or a preselected period of time elapses. If the matching condition does not exist after the preselected period of time elapses, then the current torque value is changed at a second rate of change until the matching condition exists and the current torque value corresponds to the desired torque value. In the preferred embodiment, the second rate of change is greater than the first.
The preferred rate of change is determined within an available window of torque values. The available window begins at an initial current torque value and progressively expands so that a maximum and minimum limit of the available window progressively increase and decrease, respectively. The maximum limit increases until it corresponds to the desired torque value. The minimum limit decreases until it corresponds to a predetermined absolute minimum torque value. The predetermined absolute minimum torque value is that torque which is minimally necessary to prevent the engine of the vehicle from stalling.
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Carey Sean
De Vore James
Huber Jon M.
Carlson & Gaskey & Olds
Louis-Jacques Jacques H.
ZF Meritor LLC
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