Speed filter

• US 20040181353A1
• Filed: 05/11/2004
• Published: 09/16/2004
• Est. Priority Date: 05/09/2001
• Status: Active Grant

• Current Assignee: MTU Friedrichshafen GmbH (Rolls-Royce Holdings Plc)
• Original Assignee: MTU Friedrichshafen GmbH (Rolls-Royce Holdings Plc)
• Inventors: Doelker, Armin
• Granted Patent: US 6,873,941 B2
• Time in Patent Office: Days
• US Class Current: 702/96
• CPC Class Codes: F02D 2041/1409 using at least a proportional, integral or derivative controller
• CPC Class Codes: F02D 2041/1418 Several control loops, either as alternatives or simultaneous
• CPC Class Codes: F02D 2041/1432 the system including a filter, e.g. a low pass or high pass filter
• CPC Class Codes: F02D 31/007 controlling fuel supply
• CPC Class Codes: F02D 41/0097 using means for generating speed signals
• CPC Class Codes: G01P 3/489 Digital circuits therefor

Abstract

The invention proposes a speed filter (11) for an internal combustion engine. The speed filter (11) comprises a calculation rule (BV(i)), which is used to eliminate a torsional vibration of the i^th order completely or partially. The dynamics as well as the robustness of the speed control loop are increased in this way.

Claims

1. Speed filter for an internal combustion engine (1) whose speed is detected in the form of tooth timing values of a shaft and where from the tooth timing values by means of a filter a filtered tooth timing value, corresponding to the actual speed value, is calculated, characterized in that the speed filter (11) comprises a calculation rule (BV(i), i=0.5, 1, 1.5, . . . ) for the complete or partial elimination of a torsional vibration of the i^th order and by means of the calculation rule (BV(i)) the filtered tooth timing value (y(k), k=1,2,3 . . . ) is determined (y(k)=f(BV(i))) by adding a current tooth timing value (U(k)) and earlier tooth timing values (U(k−

(N/2)), U(k−

(N/3)).

2. Speed filter (11) according to claim 1, characterized in that the earlier tooth timing values (U(k−

(N/2)), U(k−

(N/3)) are weighted through evaluation factors (k1, k2, . . . ).

3. Speed filter (11) according to claim 1 and claim 2, characterized in that the filtered tooth timing value (y(k)) additionally is determined by means of a compensating member (15), wherein the input variable (y1(k)) of the compensating member (15) corresponds to the output variable of the calculation rule (BV(i)).

4. Speed filter (11) according to claim 3, characterized in that the compensating member (15) consists of at least one differential member (13) and preferably a low pass filter (14).

5. Speed filter (11) according to claims 3 and 4, characterized in that the torsional vibration of the i^th order is completely eliminated by calculating the filtered tooth timing value (y1(k)) from the current tooth timing value (U(k)) and the tooth timing value 1/(2i) earlier by means of the calculation rule (BV(i)).

6. Speed filter (11) according to claim 5, characterized in that the calculation rule (BV(i)) is implemented in the following form:

y1(k)=y1(k−

1)+(1/F)[U(k)+k1 U(k−

F)]

with

y1(k) current filtered tooth timing value

y1(k−

1) filtered tooth timing value from 2/N revolutions earlier

N number of tooth timing values detected per working cycle

F N/(4i)

i order of the torsional vibration that is to be eliminated

U(k) current tooth timing value

U(k−

F) tooth timing value 1/(2i) revolutions earlier

k₁ evaluation factor;

equal to one

7. Speed filter (11) according to claims 3 and 4, characterized in that the torsional vibration of the i^th order is partially eliminated by calculating the filtered tooth timing value (y1(k)) by means of the following calculation rule (BV(i)).

y1(k)=y1(k−

1)+(1/F)[U/(k)+k1 U(k−

F)+Σ

kj U(k−

(N/(4i+(j−

1))))]

with

y1(k) current filtered tooth timing value

y1(k−

1) filtered tooth timing value from 2/N revolutions earlier

N number of tooth timing values detected per working cycle

F N/4i

i order of the torsional vibration that is to be eliminated

U(k) current tooth timing value

U(k−

F) tooth timing value 1/(2i) revolutions earlier

k1 evaluation factor;

k1<

1

control variable j from 2 to ∞

kj evaluation factors

8. Speed filter (11) according to claim 7, characterized in that the sum of the evaluation factors (k1, k2 . . . ) is set at one (k1+k2+ . . . =1).

9. Speed filter (11) according to claims 5 and 6 or 7 and 8, characterized in that the current tooth timing value (U(k)) and the earlier tooth timing values (U(k−

(N/2)), U(k−

(N/3)), . . . ) are averaged over a specifiable angle of the shaft (2).

10. Speed filter (11) according to one of the preceding claims, characterized in that the speed filter (11) is combined with another filter, particularly a mean value filter.

11. Speed filter (11) according to one of the preceding claims, characterized in that the order i of the torsional oscillation that is supposed to be eliminated is set at a fixed value or is calculated through frequency analysis.