Speed filter

• US 6,873,941 B2
• Filed: 05/04/2002
• Issued: 03/29/2005
• 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
• Primary Examiner(s): Raymond, Edward
• Application Number:
  US10/475,664
• Publication Number:
  US 20040181353A1
• Time in Patent Office: 1,060 Days
• Field of Search: 702/190, 702/34, 702/42, 702/43, 702/96, 702/142, 702/145, 702/182, 736/50, 738/565.9, 738/623.28, 738/623.29, 738/624.1, 734/94, 734/96, 735/142.9, 735/143.4
• US Class Current: 702/190
• 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 relates to a speed filter for an internal combustion engine. Said filter contains a calculation rule (BV(i)), which is used to completely or partially eliminate a speed oscillation of the i-th order, thus improving the dynamics and the robustness of the speed control loop.

Claims

1. A speed filter for an internal combustion engine whose speed is detected in a 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 an actual speed value, is calculated, comprising:

a calculation rule for the complete elimination of a torsional vibration or partial elimination of said torsional vibration of the i^th order;

wherein, by means of the calculation rule (BV(i)) certain tooth timing values are selected from earlier tooth timing-values (U(k−

(N/2)), U(k−

(N/3))) and the filtered tooth timing value (y(k), k=1,2,3 . . . ) is calculated (y(k)=f(BV(i))) by adding a current tooth timing value (U(k)) and the selected earlier tooth timing values.

2. The speed filter of claim 1, wherein the earlier tooth timing values (U(k−

(N/2)), U(k−

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

3. The speed filter of claim 1, wherein the filtered tooth timing value (y(k)) additionally is determined by means of a compensating member, wherein an input variable (y1(k)) of the compensating member corresponds to an output variable of the calculation rule (BV(i)).

4. The speed filter of claim 3, wherein the compensating member includes at least one differential member and may include a low pass filter.

5. The speed filter of claim 3, wherein 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 first calculation rule (BV(i)).

6. The speed filter of claim 5, wherein the calculation rule (BV(i)) is executed in the following form:

y1(k)=y1(k−

1)+(1/F) [U(k)+k1 U(k−

F)],

with,

y1(k) being said current filtered tooth timing value,

y1(k−

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

N being a number of tooth timing values detected per working cycle,

F being N/(4i),

i being the order of the torsional vibration that is to be eliminated,

U(k) being said current tooth timing value,

U(k−

F) being a tooth timing value 1/(2i) revolutions earlier, and

k1 being an evaluation factor equal to one.

7. The speed filter of claim 3, wherein the torsional vibration of the i^th order is partially eliminated by calculating the filtered tooth timing value (y1(k)) as follows by means of the 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) being said current filtered tooth timing value,

y1(k−

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

N being a number of tooth timing values detected per working cycle,

F being N/4i,

i being the order of the torsional vibration that is to be eliminated,

U(k) being said current tooth timing value,

U(k−

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

k1 being an evaluation factor, where k1<

1,

j being a control variable from 2 to ∞

, and

kj being evaluation factors.

8. The speed filter of claim 7, wherein the sum of the evaluation factors (k1, k2 . . . ) is set at the value one (k1+k2+ . . . =1).

9. The speed filter of claim 5, wherein 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.

10. The speed filter of claim 1, wherein the filtered tooth timing value (y1(k)) is filtered with another filter, particularly an average filter.

11. The speed filter of claim 1, wherein 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.

12. A speed filter for an internal combustion engine, a speed of said engine being detected in a form of tooth timing values of a shaft, comprising:

a calculation rule for complete elimination of a torsional vibration and/or partial elimination of an i^th order of said torsional vibration;

wherein a filtered tooth timing value is calculated from said tooth timing value by said calculation rule.

13. The speed filter of claim 12, wherein said calculation rule adds a current tooth timing value to selected earlier tooth timing values to generate said filtered tooth timing value.

14. The speed filter of claim 13, wherein said selected earlier tooth timing values are weighted through a plurality of evaluation factors.

15. The speed filter of claim 13, wherein said filtered tooth timing value is further determined by a compensating member, an input variable of said compensating member corresponding to an output variable of said calculation rule.

16. The speed filter of claim 15, wherein the compensating member includes at least one differential member.

17. The speed filter of claim 16, wherein the compensating member includes a low pass filter.

18. The speed filter of claim 17, wherein the torsional vibration of the i^th order is completely eliminated by calculating said filtered tooth timing from said current tooth timing value and a tooth timing value 1/(2i) earlier.

19. The speed filter of claim 18, wherein the calculation rule is executed in the following form:

y1(k)=y1(k−

1)+(1/F) [U(k)+k1 U(k−

F)],

wherein

y1(k) is a current filtered tooth timing value,

y1(k−

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

N is a number of tooth timing values detected per working cycle,

F is N/(4i),

i is the order of the torsional vibration that is to be eliminated,

U(k) is said current tooth timing value,

U(k−

F) is said tooth timing value 1/(2i) revolutions earlier, and

k1 is an evaluation factor, where k1 is equal to one.

20. The speed filter of claim 15, wherein said torsional vibration of the i^th order is partially eliminated by calculating said filtered tooth timing value in the following form:

y1(k)=y1(k−

1)+(1/F) [U/(k)+k1 U(k−

F)+Σ

kj U(k(N/(4i+(j−

1))))],

wherein

y1(k) is said current filtered tooth timing value,

y1(k−

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

N is a number of tooth timing values detected per working cycle,

F is N/4i,

i is the order of the torsional vibration that is to be eliminated,

U(k) is said current tooth timing value,

U(k−

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

k1 is an evaluation factor, where k1<

1,

j is a control variable ranging from 2 to ∞

, and

kj are evaluation factors.

21. The speed filter of claim 20, wherein a sum of evaluation factors kj equals one.

22. The speed filter of claim 19, wherein said current tooth timing value and earlier tooth timing values are averaged over a specifiable angle of said shaft.

23. The speed filter of claim 20, wherein said current tooth timing value and earlier tooth timing values are averaged over a specifiable angle of said shaft.