Method and arrangement for controlling a drive unit

Details Method and arrangement for controlling a drive unit Method and arrangement for controlling a drive unit

1999-08-30

2001-09-25

Wolfe, Willis R. (Department: 3747)

Data processing: vehicles, navigation, and relative location

Vehicle control, guidance, operation, or indication

With indicator or control of power plant

C701S103000

Reexamination Certificate

active

06295501

ABSTRACT:

BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,692,472 discloses a method and an arrangement for controlling a drive unit. Here, to control the drive unit, the torque or the power of the drive unit is adjusted via an electrical path at least in dependence upon the position of a operator-controlled element actuable by the driver. To monitor this control, a maximum permissible torque or a maximum permissible power is determined on the basis of the position of the operator-controlled element. The actual torque should not exceed the maximum permissible torque and the actual power of the drive unit should not exceed the maximum permissible power. In some applications, for example, in internal combustion engines having gasoline direct injection systems or for diesel engines, it can be provided that this monitoring is only active when the idle state of the drive unit is detected via the position of the accelerator pedal. The idle state of the drive unit is, as a rule, detected in that at least one signal quantity, which represents the position of the actuable operator-controlled element, is compared to a threshold value and a drop below this threshold value represents a released accelerator pedal and therefore the idle state of the drive unit. For these reasons, there are cases of application wherein a reliable idle detection has special significance.
However, this is not always guaranteed only with the comparison to a fixed pregiven threshold value. For example, because of external influences, such as mechanical faults or a foot mat lying on the pedal, idle detection can no longer be possible so that unwanted operating situations are possible via so-called secondary faults in the described application examples.
U.S. Pat. No. 5,229,957 discloses that the mechanical stops of a position transducer, which detects the position of an accelerator pedal, can be learned, that is, can be adapted to changes. This takes place in that the actual end value of the position signal is stored and is substituted by a new position signal value when the actually measured position signal value exceeds or drops below the stored signal position value. In order to prevent that a defectively learned value leads to a continuously defective shift of the position signal, it is provided that, when for a predetermined time at least one of the stored end values is no longer reached, these end values are reset to pregiven start values. On the basis of the at least one stored end value, the actual position signal of the position transducer is determined while considering the measured voltage signal and a pregiven calibration procedure. The actual position signal is then evaluated for controlling the drive unit.
SUMMARY OF THE INVENTION
It is an object of the invention to provide measures in a control system of this kind for a drive unit with the aid of which a reliable idle detection is possible even in unfavorable cases.
The method of the invention is for controlling a drive unit for which at least one measurement signal quantity (U
1
) having at least one end value is detected with the drive unit being controlled in dependence upon the end value. The method includes the steps of: presetting several signal quantity regions (I to V) for the end value of the measurement signal quantity (U
1
) with the signal quantity regions (I to V) being assigned respective calibration values (UPWGRES, UPWGUR, UPWGERS, UPWGNOT); determining the one of the signal quantity regions (I to V) which the end value of the measurement signal quantity (U
1
) has reached; selecting the calibration value assigned to the one signal quantity region; and, converting the measurement signal quantity (U
1
) into a relative measurement quantity (wped) on the basis of the selected calibration value.
The solution provided by the invention permits a reliable detection of idle in that a position transducer (accelerator pedal value transducer) is monitored to detect the actuation of an accelerator pedal so that even for an unwanted operating state, the idle detection is reliably ensured at the latest in the next-following driving cycle. A reliable detection of idle is ensured in an especially advantageous manner notwithstanding the above-described fault situations.
It is especially advantageous that a possible accelerator pedal inactive path (a pedal inactive path or lost motion which, as a rule, is an unpleasant sensation for the driver) is only significantly increased when a serious fault is present at an accelerator pedal value transducer.
Under specific conditions, which permit a conclusion to be drawn as to a fault in the accelerator pedal value transducer, idle can be reliably detected by the selection of another calibration procedure. It is especially advantageous in this context that the calibration can be changed (that is, reset) when a correct operation of the accelerator pedal value transducer was detected.
It is especially advantageous that the influence of transition resistances (varying resistance between slider and resistor of potentiometer because of wear) is precluded when utilizing potentiometers to detect the accelerator pedal position.
Even a mat lying on the accelerator pedal no longer presents a problem and cannot lead to unwanted operating states. In the best case, an immediate reset to the standard calibration takes place in such a fault situation.
It is especially advantageous that the return to a standard calibration is also possible during the actual driving cycle. This prevents a motor start or start attempt with an actuated accelerator pedal to lead to an increased pedal inactive path (lost motion path wherein there is no response).


REFERENCES:
patent: 5229957 (1993-07-01), Hahn et al.
patent: 5521825 (1996-05-01), Unuvar et al.
patent: 5581465 (1996-12-01), Adler et al.
patent: 5692472 (1997-12-01), Bederna et al.
patent: 5774820 (1998-06-01), Linden
patent: 6044318 (2000-03-01), Bourdon et al.
patent: 6102002 (2000-08-01), Gimmler et al.

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