JP2658623B2 - Misfire detection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a misfire detecting device for detecting the presence or absence of a misfire from the rotation period of a ring gear, and more particularly to a device capable of detecting missing teeth of the ring gear.

[0002]

2. Description of the Related Art As a conventional example of a misfire detecting device for an internal combustion engine, there is the following device (Japanese Patent Laid-Open No. 58-19532).
Reference). That is, the electromagnetic pickup sensor is disposed so as to face the teeth of the ring gear outer peripheral wall attached to the end of the crankshaft, and a pulse signal corresponding to the teeth of the ring gear is output from the electromagnetic pickup sensor to the misfire determination device.

[0003] The misfire judging device judges the presence or absence of a misfire based on the input period or the number of inputs of the pulse signal.

[0004]

When the teeth of the ring gear are chipped or worn, the output period of the pulse signal from the electromagnetic pickup sensor changes or the output of the pulse signal decreases, and erroneous misfire determination occurs. There is a problem that the accuracy of misfire detection is deteriorated. The present invention has been made in view of such a situation, and provides a misfire detection device capable of detecting missing teeth of a ring gear and preventing erroneous misfire determination.

[0005]

For this reason, the present invention is based on FIG.
As shown in FIG. 5, a plurality of teeth are formed at predetermined intervals on an outer peripheral wall of a ring gear A attached to an end of a crankshaft, and an electromagnetic pickup sensor B is provided so as to face the outer peripheral wall of the ring gear.
And misfire determining means C for determining whether or not a misfire has occurred based on a pulse signal from the electromagnetic pickup sensor B.
A rotation cycle measuring means D for measuring a cycle of engine rotation between predetermined crank angles based on a pulse signal from the electromagnetic pickup sensor B;
A period determining means E for determining whether or not the measured period has changed by a predetermined value or more; and a tooth missing determining means F for determining that a tooth missing of the ring gear A has occurred when the period has changed by a predetermined value or more. And a misfire determination canceling means G for canceling the misfire determination by the misfire determination means C when it is determined that the tooth missing has occurred.

[0006]

In this way, it is determined that a missing tooth has occurred in the ring gear when the rotation cycle has changed by a predetermined value or more, and at this time, the misfire determination is canceled, thereby preventing erroneous misfire determination.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2, a disk-shaped ring gear 3 is attached to an end of a crankshaft 2 of an engine 1.
A large number of teeth are formed on the outer peripheral wall of the ring gear 3 at substantially constant intervals. An electromagnetic pickup sensor 4 is provided so as to face the outer peripheral wall of the ring gear 3, and the electromagnetic pickup sensor 4 outputs a pulse signal to a misfire determination device 5 composed of a microcomputer or the like every time the teeth of the ring gear 3 pass forward. .

The misfire judging device 5 operates according to the flowchart of FIG. Here, the misfire determination device 5 constitutes misfire determination means, rotation cycle measurement means, cycle determination means, missing tooth determination means, and misfire determination cancellation means. Next, the operation will be described with reference to the flowchart of FIG. In step S1, a period TNEW in which a predetermined number of teeth of the ring gear 3 passing through the electromagnetic pickup sensor 4 are read for each cylinder is measured based on a pulse signal from the electromagnetic pickup sensor 4.

In S2, the cycle TNEW measured this time is set as T1 as the latest cycle, T1 set in the previous routine is set as T2 as the cycle immediately before, and T2 set in the previous previous routine is set as 2 The previous cycle is set to T3, and the data T3 to T3 of the previous, fourth, and fifth times are further set.
6 is set as the old data T4 to T7 once and stored.

In S3, a calculation value A for determining missing teeth is calculated by the following equation based on the cycle set in S2. A = {5 × (T6−T7) − (T1−T6)} / (T7) ^{3 In} S4, the toothless determination reference value is calculated based on the detected engine speed and engine load (eg, throttle valve opening). Search from the map based on.

In S5, the calculated value A obtained in S3
It is determined whether or not exceeds the determination reference value searched in S4. If YES, the process proceeds to S6, and if NO, the process proceeds to S8. In step S6, when the calculated value A exceeds the reference determination value, it is determined that the tooth portion of the ring gear has a missing tooth and the cycle is rapidly increased, and it is determined that the missing tooth has occurred.

At S7, the occurrence of tooth missing is stored as flag = 1. On the other hand, in S8, it is determined that there is no tooth missing in the tooth portion of the ring gear, and in S9, the fact that there is no tooth missing is stored as flag = 0. In S10, based on the cycle set in S2, a misfire determination calculation value B is calculated by the following equation.

B = {(T4−T7) − (T1−T4)} / (T7) ⁴ Note that the arithmetic expression A for missing teeth is used as an arithmetic expression for misfire determination.
May be used. In S11, the misfire determination reference value is
A search is made from a map based on the detected engine speed and engine load. In S12, it is determined whether or not the calculated value B obtained in S10 exceeds the misfire determination reference value searched in S11. If YES, it is determined that a misfire has occurred. Proceed to S15.

In S13, it is determined whether or not the flag = 1, that is, whether or not the tooth portion of the ring gear has a missing tooth.
In the case of ES, that is, when a missing tooth occurs, the process proceeds to S15, and in the case of NO, the process proceeds to S14. In S14, it is determined that a misfire has occurred, and in S15, it is determined that no misfire has occurred.

Therefore, even if it is determined in S12 that a misfire has occurred, if it is determined in S13 that the ring gear is missing teeth, the determination of the occurrence of misfire in S12 is canceled and it is determined that there is no misfire. For this reason, when a missing tooth occurs in the ring gear, it is not determined that a misfire has occurred. Therefore, it is possible to prevent an erroneous determination that a misfire has occurred, thereby greatly improving the misfire determination accuracy.

[0016]

As described above, according to the present invention, it is determined that the ring gear has chipped when the rotation period changes by a predetermined value or more, and the misfire determination is canceled at this time. In the event of a missing tooth of the ring gear, erroneous determination of misfire occurrence can be prevented, and misfire detection accuracy can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention.

FIG. 2 is a configuration diagram showing one embodiment of the present invention.

FIG. 3 is a flowchart of the above.

[Explanation of symbols]

 2. Crankshaft 3. Ring gear 4. Electromagnetic pickup sensor 5. Misfire determination device

Claims (1)

(57) [Claims] A plurality of teeth are formed at predetermined intervals on an outer peripheral wall of a ring gear attached to an end of a crankshaft, and an electromagnetic pickup sensor is disposed so as to face the outer peripheral wall of the ring gear, and a pulse from the electromagnetic pickup sensor is provided. A misfire detection device for an internal combustion engine, comprising: a misfire determination unit for determining whether or not a misfire has occurred based on a signal; a rotation cycle for measuring an engine rotation cycle between predetermined crank angles based on a pulse signal from the electromagnetic pickup sensor; Measuring means, cycle determining means for determining whether the measured cycle has changed by a predetermined value or more, and missing tooth determination for determining that tooth missing of the ring gear has occurred when the cycle has changed by a predetermined value or more Means, misfire determination canceling means for canceling the misfire determination by the misfire determination means when it is determined that tooth missing has occurred, Misfire detecting device for an internal combustion engine characterized by comprising.