JP2002309994A - Abnormality detector for timing winding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid interference between a valve and a piston at the occurrence of an abnormal state by accurately detecting the phase shift of a camshaft caused by the elongation of a timing chain and the wear of a timing belt. SOLUTION: A counter Sn for counting crank angle signals is reset to 0 in the missing position of the crank angle signal. The head of cam signals is initialized to be outputted in the missing position of the crank angle signal. When there is no shift in the phase of the camshaft, the value of the counter Sn at the output of the head of the cam signals shows a fixed value, but if the phase is shifted, the value of the counter Sn shows a different value. Consequently, when the value of the counter Sn at the output of the head of the cam signals does not coincide with the initial value, the occurrence of a phase shift is determined, and an alarm lamp is lighted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting an abnormality of a timing winding member such as a timing chain or a timing belt in an engine.

[0002]

2. Description of the Related Art Conventionally, in an engine, a timing winding member such as a timing chain or a timing belt is wound between a crank sprocket and a cam sprocket, and a camshaft is driven from a crankshaft via the timing winding member. Such a configuration is generally used (see Japanese Patent Application Laid-Open No. 2001-027109).

[0003]

By the way, in an engine using the above-mentioned timing chain or timing belt, the phase of the camshaft with respect to the crankshaft is delayed from the normal state due to the elongation of the timing chain and the wear of the timing belt. May shift. Therefore, even if the opening / closing timing of the valve changes due to the phase delay of the camshaft, a piston recess is provided or the valve lift is limited so that interference between the piston and the valve does not occur. The clearance between the valve and the valve was made to have a margin.

However, the setting of the piston recess and the setting of the valve lift amount in response to the occurrence of the elongation of the timing chain and the abrasion of the timing belt require the output and fuel consumption of the engine in a normal state where the elongation and the abrasion do not occur. -There was a problem that the exhaust performance was limited. The present invention has been made in view of the above problems, and provides an apparatus capable of accurately detecting an abnormal state such as elongation of a timing chain or wear of a timing belt. An object of the present invention is to provide a device capable of avoiding interference with a piston, thereby reducing the restriction on engine performance in a normal state and exhibiting high performance.

[0005]

SUMMARY OF THE INVENTION Therefore, an invention according to claim 1 is an apparatus for detecting an abnormality in a timing wrapping member bridged between a crank sprocket and a cam sprocket of an engine, and detects a crank angle. A phase difference detector that detects a phase shift of the camshaft with respect to the crankshaft based on the crank angle and the cam angle detected by the crank angle detector and a cam angle detector that detects the cam angle. Means and an abnormality determination means for outputting an abnormality determination signal of the timing winding member when the phase shift detected by the phase shift detection means is equal to or greater than a threshold value.

According to this configuration, a shift of the rotation phase of the camshaft with respect to the crankshaft due to elongation of the timing chain or wear of the timing belt is obtained from the detection results of the crank angle and the cam angle. At some point, an abnormality determination signal is output. According to the second aspect of the present invention, the crank angle detecting means is configured to output a crank angle signal for each unit crank angle, and the crank angle signal is configured to be partially omitted. The detecting means outputs a cam signal at least in a section where the crank angle signal is missing. The phase shift detecting means includes a counter for counting the crank angle signal, and a crank angle signal based on a cycle of the crank angle signal. Reference position detection means for detecting a missing section of the first section and detecting the first crank angle signal after the missing section as a reference position signal; reset means for resetting the counter when the reference position signal is detected; The value of the counter at the time of the generation of the cam signal corresponding to the position where the omission occurs is represented by data indicating the phase shift. A counter value output means for outputting Te were assumed to be configured to include.

With this configuration, the counter counts the crank angle signal and is reset based on the missing position of the crank angle signal, so that the counter indicates a constant count number with respect to the crank angle. In the state where the cam shaft phase shift has not occurred, the cam signal is output at the position where the crank angle signal is missing, and the counter at that time shows a constant value, but the cam shaft phase shift occurs. When the output position of the cam signal deviates from the disengagement position, the value of the counter at the position where the cam signal is generated indicates a different value due to the deviation of the position where the cam signal is generated. , The phase shift of the camshaft is detected.

According to the third aspect of the present invention, the abnormality determination means outputs the abnormality determination signal when it is determined that the occurrence of a phase shift greater than or equal to a threshold value has occurred continuously for a predetermined number of times. According to such a configuration, even if it is determined that a phase shift greater than or equal to the threshold value has occurred, an abnormality determination signal is not output immediately. Outputs a judgment signal.

In the invention according to claim 4, the threshold value in the abnormality determination means is set in advance based on a phase shift range in which interference between the piston and the valve occurs.
According to such a configuration, the threshold value is set based on a phase shift state in which interference between the piston and the valve occurs, and an abnormality determination signal can be output in a state before the interference occurs.

[0010] According to the fifth aspect of the present invention, a warning means for issuing a warning when an abnormality determination signal is output from the abnormality determination means is provided. According to such a configuration, when a deviation of the rotation phase of the camshaft from the crankshaft due to elongation of the timing chain or wear of the timing belt becomes equal to or larger than the threshold, a warning (buzzer, lamp lighting, etc.) indicating occurrence of the phase deviation is issued. Prompts the user to replace the timing chain or timing belt.

In the invention according to claim 6, an engine stop means for forcibly stopping the engine when an abnormality determination signal is output from the abnormality determination means is provided. According to this configuration, when the rotation phase shift of the camshaft with respect to the crankshaft due to the elongation of the timing chain or the wear of the timing belt becomes equal to or larger than the threshold, the engine is forcibly stopped, and the phase shift equal to or larger than the threshold occurs. Prohibit engine operation in the state.

In the invention according to claim 7, the engine stopping means forcibly stops the supply of fuel to the engine. According to this configuration, when the rotation phase shift of the camshaft with respect to the crankshaft due to elongation of the timing chain or wear of the timing belt becomes equal to or larger than the threshold,
The engine is stopped by forcibly stopping the fuel supply to the engine.

According to an eighth aspect of the present invention, the engine is an engine that performs spark ignition combustion using a spark plug, and the engine stopping means forcibly stops spark ignition using the spark plug. According to this configuration, when the rotation phase shift of the camshaft with respect to the crankshaft due to elongation of the timing chain or wear of the timing belt becomes equal to or larger than the threshold value, the spark plug is forcibly stopped and the engine is stopped. Is done.

According to a ninth aspect of the present invention, there is provided a variable valve timing mechanism for changing a valve timing of the engine, and the variable valve timing mechanism is controlled when an abnormality determination signal is output from the abnormality determination means. Phase shift correcting means for changing the valve timing in a direction in which the phase shift is eliminated is provided. According to this configuration, when the rotational phase shift of the camshaft with respect to the crankshaft due to elongation of the timing chain or wear of the timing belt becomes equal to or greater than the threshold value, the direction of the phase shift due to the elongation or wear is eliminated in order to eliminate this phase shift state. Adjust the camshaft phase in the opposite direction.

[0015]

According to the first aspect of the present invention, it is possible to accurately detect that the deviation of the rotation phase of the camshaft from the crankshaft due to the elongation of the timing chain or the wear of the timing belt has exceeded the threshold value. Thus, there is an effect that it is possible to accurately execute the countermeasure accompanying the occurrence of the phase shift.

According to the second aspect of the invention, there is an effect that the phase shift of the camshaft with respect to the crankshaft can be detected reliably and easily based on the count number of the crank angle signal. According to the third aspect of the invention, there is an effect that the occurrence state of the phase shift equal to or larger than the threshold value can be more accurately determined.

According to the fourth aspect of the present invention, it is possible to determine an abnormality at a stage before the interference between the piston and the valve occurs, and it is possible to avoid the occurrence of the interference. is there. According to the fifth aspect of the present invention, the user is warned of the occurrence of a phase shift greater than or equal to the threshold, and is prompted to replace the timing chain / timing belt, so that the user is left until the interference between the piston and the valve occurs. This has the effect of avoiding the situation.

According to the present invention, the engine is forcibly stopped when it is determined that the phase shift is equal to or larger than the threshold value, so that the operation of the engine in a state where the piston and the valve interfere with each other can be performed. There is an effect that it can be avoided. According to the ninth aspect of the present invention, the variable valve timing mechanism absorbs the phase shift of the camshaft due to the elongation of the timing chain and the abrasion of the timing belt. There is an effect that the engine can be operated at the valve timing.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. The vehicle engine 1 shown in FIG.
An in-line four-cylinder engine of an OHC mechanism, which is operated by a timing chain or a timing belt (wrapping member) 5 which is wound around the crank sprocket 2, the intake cam sprocket 3, the exhaust cam sprocket 4, and the sprockets 2 to 4. The mechanism is configured.

FIG. 2 is an enlarged sectional view of the cylinder head of the engine 1. An intake port 12 and an exhaust port 13 are formed in the cylinder head 11.
2 is provided with an intake valve 14 and the exhaust port 13 is provided with an exhaust valve 15. The intake valve 14 and exhaust valve 15 are driven to open and close by rocker arms 18 and 19 by an intake camshaft 16 and an exhaust camshaft 17.

In FIG. 2, reference numeral 20 denotes a spark plug. As shown in FIG. 1, the crankshaft is provided with a crank angle sensor 31 (crank angle detecting means) for detecting a crank angle, and the exhaust camshaft 17 is provided with a cam angle sensor 32 (cam angle) for detecting a cam angle. Detection means). In the present embodiment, the crank angle sensor 31 is a sensor that generates a crank angle signal every 10 degrees of the crank angle. However, the crank angle sensor 31 is configured to cause a drop in the crank angle signal at two points at 180 degrees intervals (FIG. 3). reference).

The above-mentioned 180 deg is an angle corresponding to the stroke phase difference between the cylinders in the four-cylinder engine of this embodiment. Therefore, for example, if there are six cylinders, there are three places at 120 deg intervals. However, the position at which the crank angle signal is lost is set to one position per rotation of the crankshaft regardless of the number of cylinders.
It may be a part. Further, the unit crank angle for generating the crank angle signal is not limited to 10 degrees.

The cam angle sensor 32 generates a cam signal at the missing position of the crank angle signal generated for each angle corresponding to the stroke phase difference as described above, and, following the cam signal at the missing position, determines the cylinder. Cam signals of the number corresponding to the cylinder number to be generated are generated at regular intervals (see FIG. 3). That is, assuming that the ignition order is # 1 cylinder → # 3 cylinder → # 4 cylinder → # 2 cylinder, every 180 degrees of crank angle (90 degrees of cam angle), 1
, Three, four, and two cam signals are generated. In FIG. 3, after one cam signal corresponding to the # 1 cylinder is output, the next missing position is set at the top. Shows how three cam signals corresponding to # 3 cylinder are output.

The detection signals of the crank angle sensor 31 and the cam angle sensor 32 are input to a control unit 33.
The control unit 33 includes a microcomputer, detects the occurrence of a phase shift of the camshaft due to the elongation of the timing chain or the wear of the timing belt, and detects a phase shift of a threshold value or more according to a program shown in a flowchart described later. When the occurrence is detected, processing for coping with the state is executed.

That is, the control unit 33 has software functions as phase shift detecting means and abnormality determining means. The flowchart of FIG. 4 is executed every time the crank angle signal is generated. In step S1, the time from the previous execution of this routine to the present time, that is, the generation cycle T of the crank angle signal is measured.

In step S2, the cycle ratio Tr between the latest measured cycle Tn and the previous value Tn-1 of the cycle T is calculated as Tr = Tn / Tn-1. The period ratio Tr is a value near 1 because the interval between the occurrences of the crank angle signal is constant in portions other than the portion where the crank angle signal is missing, but at the missing position, as shown in FIG. After the period becomes longer and becomes a large value exceeding 1, the next period shows a value less than 1 because the period returns from the period at the missing position to the normal period.

Therefore, in step S3, a threshold Trs which does not exceed due to the rotation fluctuation but exceeds when the latest cycle T is the result of measuring the missing position, and the cycle ratio Tr calculated in step S2 are Compare.
When the cycle ratio Tr is equal to or larger than the threshold Trs, it is determined that the latest cycle T is a detection of a missing position,
Proceeding to step S4, a reference position signal synchronized with the present crank angle signal is generated, and in the next step S5, the value of the counter Sn for counting the crank angle signal is reset to zero (reset means).

On the other hand, when it is determined in step S3 that the period ratio Tr is less than the threshold value Trs, the process proceeds to step S6, and the value of the counter Sn is increased by one. By the above processing, the counter Sn is reset to 0 for each of the reference position signals (each of the missing positions of the crank angle signal), and counts the number of crank angle signals after the generation of the reference position signal.

The flowchart of FIG. 5 is executed every time a cam signal is generated. In step S11, the time from the previous execution of this routine to the current execution, that is, the cam signal generation cycle Tc is measured. In step S12, the cycle Tc is converted into a crank angle θc based on an engine rotation speed calculated based on, for example, the generation cycle of the reference position signal and the number of crank angle signals generated in a predetermined time frame.

In step S13, the crank angle θc
By comparing the current cam signal with the threshold value θs, it is determined whether or not the current cam signal is the head signal to be output at the position where the crank angle signal is missing. The cycle of generating the cam signal is a short cycle of about 15 deg between a group of signals representing the cylinder number, but when the current cam signal is the leading signal, the latest cycle is at least about 135 deg. In step S13, it is determined whether or not the current cam signal is the head signal by comparing the latest angle cycle θc with the threshold value θs.

If the latest angle cycle θc is equal to or greater than the threshold value θs, the process proceeds to step S14, and a head determination signal indicating that the current cam signal is the head is generated. FIG.
Is executed every time a head determination signal is generated. In step S21, the value of the counter Sn at the time when the head determination signal is generated is set to Sn '(counter value output means).

In step S22, the value of Sn 'is
It is determined whether the number is 16. If there is no cam shaft phase shift, the head determination signal is generated at the position where the crank angle signal is missing, and the value of the counter Sn at that time is 16 in the present embodiment (see FIG. 3). ). on the other hand,
When the phase of the camshaft is shifted to the side that is delayed due to the elongation of the timing chain or the wear of the timing belt, the position at which the head determination signal is generated is delayed with respect to the crank angle, for example, as shown in FIG. When the head determination signal (head cam signal) is generated later than the signal, the value Sn ′ of the counter Sn at that time is 0,
Sn ′ ≠ 16, and it is detected that a phase shift exceeding 10 deg has occurred.

When it is determined that Sn '≠ 16 and the occurrence of a phase shift exceeding the threshold value is detected, the process proceeds to step S23,
The number of the counter C for counting the number of times the phase shift is detected is increased by one. As described above, when Sn ′ ≠ 16, if the phase shift of the camshaft is detected,
As described above, a phase shift exceeding 10 deg will be detected as an abnormal state. However, when it is desired to set a larger allowable phase shift amount, Sn ′ ≠ 16 and 16−Sn ′ ≦ α It is sufficient to proceed to step S23 on condition that (α ≦ 15).

For example, if α = 15 and the abnormality is determined when Sn ′ ≠ 16 and 16−Sn ′ ≦ 15, if Sn ′ = 0, the abnormality is not determined without satisfying the condition. If the phase shifts by more than 20 deg and Sn ′ ≧ 1, the condition of 16−Sn ′ ≦ 15 is satisfied and the abnormality is determined. Therefore,
16-Sn ′, the amount of phase shift to be determined as abnormal by the value α to be compared is changed in units of 10 deg,
Is set appropriately based on a phase shift state in which interference between the piston and the valve occurs, at least at a stage before the occurrence of the interference.

When increasing the resolution of the phase shift,
What is necessary is just to make the generation cycle of the crank angle signal shorter than 10 deg. In step S24, it is determined whether or not the value of the counter C incremented by one in step S23 is equal to or greater than a predetermined value Cs. If it is equal to or greater than the predetermined value Cs, the process proceeds to step S25.

On the other hand, if Sn '= 16 and it is determined that there is no occurrence of a phase shift exceeding the threshold, the process proceeds to step S26, where the counter C is reset to zero. Therefore, when it is determined that Sn ′ ≠ 16 continuously for a predetermined number of times or more, the process proceeds to step S25. In step S25, an abnormality determination signal is output, and a warning lamp 35 (warning means) provided near the driver's seat of the vehicle is turned on based on the abnormality determination signal, and the user is notified of elongation of the timing chain or wear of the timing belt. Warns that the phase of the camshaft is shifted toward the delay side.

A buzzer may be used in place of the warning light or together with the warning light. The above warning prompts the user to replace the timing chain or the timing belt or to perform maintenance and inspection. The state in which the phase of the camshaft is out of alignment due to the elongation of the timing chain or the wear of the timing belt is left as it is. To prevent the piston and the valve from interfering with each other.

The flowchart of FIG. 7 differs from the flowchart of FIG. 6 only in the processing content when the occurrence of the phase shift is determined continuously. In the flowchart of FIG. 7, the occurrence of the phase shift is determined continuously for a predetermined number of times, and step S2 is performed.
In 5 ', the engine 1 is forcibly stopped (engine stop means).

Forcibly stopping the engine 1 is performed by stopping the supply of fuel to the engine 1 and / or
This is done by stopping the spark ignition. If the engine 1 is forcibly stopped, the operation in a state where the piston and the valve interfere with each other can be reliably avoided. Here, Sn ′ ≠ 1
6 (Sn '= 0) is detected, a warning is issued, and then, as a result of the elongation of the timing chain or the abrasion of the timing belt being left as it is, the phase shift further increases, and Sn' ≠ 16 and 16 −Sn ′ ≦ α (α ≦ 1
When 5) is reached, the engine 1 can be stopped by judging that the state is just before the piston and the valve interfere with each other.

As shown in FIG. 1, the exhaust-side camshaft 17 provided with the cam sensor 32 is, for example, disclosed in
By rotating only the cam shaft side with respect to the cam sprocket 5 fixed by a timing chain or a timing belt as disclosed in JP-A-068306,
When the variable valve timing mechanism 36 for advancing the phase of the camshaft with respect to the crankshaft is provided, a process as shown in the flowchart of FIG. 8 can be performed as a process when the phase shift is detected. is there.

In the flowchart of FIG. 8, in step S25a, the phase of the exhaust side camshaft 17 is advanced by a predetermined angle by controlling the variable valve timing mechanism 36 (phase shift correcting means).
In b, it is determined whether or not Sn ′ = 16 as a result of the process for advancing the phase. If Sn '= 16, it means that the phase of the camshaft with respect to the crankshaft has returned to the normal state, and the advancing process of step S25a until it is determined that Sn' = 16 in step S25b. To be repeated.

Note that the phase abnormality is defined as Sn ′ ≠ 16 and 1
6-Sn ′ ≦ α (α ≦ 15), when it is determined that 16−Sn ′> α even if Sn ′ ≠ 16, it can be determined that the value is within the allowable range. Sn '
The advance processing may be stopped when> α is satisfied.
If the camshaft phase does not return to the normal state even after the lead angle is corrected by a predetermined angle or more, stop further lead angle correction,
A warning should be issued.

Further, since the phase shift of the camshaft can be determined in units of 10 deg from the value of Sn ', the amount of advance correction of the variable valve timing mechanism 36 can be set according to the amount of phase shift. According to the above configuration, even if the phase of the camshaft is deviated due to the elongation of the timing chain or the wear of the timing belt, the phase of the camshaft can be returned to the vicinity of the normal phase state by the control of the variable valve timing mechanism 36. Interference can be avoided, and engine operation with the initial characteristics can be maintained.

However, since the elongation of the timing chain or the wear of the timing belt itself is not eliminated,
More preferably, the phase of the camshaft is adjusted by the variable valve timing mechanism 36 while issuing a warning prompting replacement of the timing chain or the timing belt.

[Brief description of the drawings]

FIG. 1 is a view showing a valve operating mechanism of an engine.

FIG. 2 is a partially enlarged sectional view showing a cylinder head portion of the engine.

FIG. 3 is a time chart showing characteristics of various signals.

FIG. 4 is a flowchart showing a crank angle signal counting process.

FIG. 5 is a flowchart showing a cam signal head determination process.

FIG. 6 is a flowchart illustrating a first embodiment of a process for determining a phase shift of a camshaft and a process when a shift occurs.

FIG. 7 is a flowchart illustrating a second embodiment of a process for determining a phase shift of a camshaft and processing when a shift occurs.

FIG. 8 is a flowchart showing a third embodiment of a process for determining a phase shift of a camshaft and a process when a shift occurs.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Crank sprocket 3 ... Intake side cam sprocket 4 ... Exhaust side cam sprocket 5 ... Timing chain or timing belt (wrapping member) 11 ... Cylinder head 12 ... Intake port 13 ... Exhaust port 14 ... Intake valve 15 ... Exhaust Valve 16: intake camshaft 17: exhaust camshaft 20: spark plug 31: crank angle sensor (crank angle detecting means) 32 ... cam angle sensor (cam angle detecting means) 33: control unit 35: warning light 36: variable Valve timing mechanism

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/22 330 F02D 41/22 330S F02P 11/04 302 F02P 11/04 302Z F16H 7/02 F16H 7 / 02 A 7/06 7/06 F term (reference) 3G019 CA11 CB00 DB07 3G084 BA13 BA16 BA23 BA33 DA28 EA05 EA11 EB22 EC01 EC03 FA39 3G092 AA01 AA11 BA08 BB10 CA01 CB04 CB05 DA01 DA02 DA08 EA08 EA04 EB04 EB04 JA21 JB09 JB10 KA26 LA00 LA07 MA11 MA24 NE20 PE04Z 3J049 AA03 AA08 BG10 CA02

Claims (9)

[Claims] 1. An abnormality detection device for a timing wrapping member bridged between a crank sprocket and a cam sprocket of an engine, comprising: crank angle detection means for detecting a crank angle; and cam angle detection for detecting a cam angle. Means, a phase shift detecting means for detecting a phase shift of the camshaft with respect to the crankshaft based on the detected crank angle and cam angle, and when the phase shift detected by the phase shift detecting means is not less than a threshold value An abnormality determining means for outputting an abnormality determination signal of the timing winding member; and a timing winding member abnormality detecting device, comprising: 2. The apparatus according to claim 1, wherein said crank angle detecting means outputs a crank angle signal for each unit crank angle, and
The cam angle detector is configured to output a cam signal at least in a section where the crank angle signal is missing, while the phase shift detector is configured to: A counter for counting a crank angle signal; and a reference position detecting means for detecting a missing section of the crank angle signal based on a cycle of the crank angle signal, and detecting a first crank angle signal after the missing section as a reference position signal. Resetting means for resetting the counter when the reference position signal is detected; and data indicating the phase shift, the value of the counter at the time of the generation of the cam signal corresponding to the position where the crank angle signal is missing. 2. A timing winding according to claim 1, further comprising: counter value output means for outputting as a value. An abnormality detection device for hanging members. 3. The abnormality determination unit according to claim 1, wherein the abnormality determination unit outputs the abnormality determination signal when it is determined that the occurrence of a phase shift greater than or equal to a threshold value has occurred continuously for a predetermined number of times. Abnormality detection device for timing winding member. 4. The apparatus according to claim 1, wherein the threshold value in the abnormality determination means is set in advance based on a phase shift range in which interference between the piston and the valve occurs. Abnormality detection device for timing winding member. 5. The timing wrapping member according to claim 1, further comprising a warning unit for issuing a warning when an abnormality determination signal is output from the abnormality determination unit. Abnormality detection device. 6. An engine stop means for forcibly stopping an engine when an abnormality determination signal is output from said abnormality determination means. Timing winding member abnormality detection device. 7. An abnormality detecting device for a timing winding member according to claim 6, wherein said engine stopping means is configured to forcibly stop fuel supply to the engine. 8. An engine in which the engine performs spark ignition combustion using a spark plug, wherein the engine stopping means forcibly stops spark ignition using the spark plug. 7. An abnormality detection device for a timing winding member according to 6. 9. A variable valve timing mechanism for changing a valve timing of the engine, and when an abnormality determination signal is output from the abnormality determination means, the variable valve timing mechanism is controlled to eliminate a phase shift. 5. An apparatus according to claim 1, further comprising a phase shift correcting means for changing a valve timing in a predetermined direction.