JP6024520B2 - Knock detection device - Google Patents

Description

  The present invention relates to a knock detection device that detects the occurrence of knock (knock) in an engine having a cam structure with a roller in a valve mechanism.

  2. Description of the Related Art Conventionally, a technique for controlling the operating state of an engine while suppressing the occurrence of knock in the engine cylinder has been developed. For example, in a spark ignition type engine, knock control is known that improves the output efficiency of the engine within a range in which knock does not occur by adjusting the ignition timing in the advance direction and retard direction. Also in a compression ignition type engine, knock control is known in which the timing of fuel injection is optimized by controlling the timing of fuel injection in accordance with the presence or absence of knock. In these knock controls, a knock sensor is used as a sensor for grasping the degree of knock.

  Knock sensors are roughly classified into a resonance type and a non-resonance type. The resonance type knock sensor extracts the vibration of the frequency component corresponding to the resonance vibration mode when the knock occurs. On the other hand, the non-resonant type knock sensor outputs the acceleration of vibration accompanying the knock. In any type of knock sensor, the magnitude and acceleration of vibration generated with the knock are acquired based on the deformation amount of the piezoelectric element incorporated in the sensor.

  Recently, a cam structure in which a roller is pivotally supported on a cam lobe has been proposed as one of cam structures constituting a valve mechanism of an engine. That is, a roller is rotatably attached to the tip of the cam lobe, and this roller is provided so as to rotate while contacting a driven member (valve tappet, rocker arm, swing arm, etc.) (for example, Patent Document 1). To 3). By applying such a cam structure with a roller, the friction at the contact point can be reduced, and the performance of the valve mechanism can be improved.

JP 2011-080372 A JP 2012-202355 A JP 2012-202356 JP

However, in knock control in an engine having a cam structure with a roller in the valve mechanism, it may be difficult to distinguish and distinguish between acceleration fluctuations caused by normal operation of the cam structure and acceleration fluctuations due to knock vibration. There is a problem that it is difficult to improve detection accuracy.
For example, in the technique of Patent Document 1, a valve acceleration peak occurs when a contact point with a valve tappet changes from a valve lift portion of a base cam to a roller body. When such a variation in acceleration is detected by the knock sensor, it may be determined that knock has occurred even though knock has not actually occurred. In this case, not only the determination accuracy of knocking is lowered, but also the controllability of the engine, fuel consumption, etc. can be lowered by this erroneous determination.

  One of the objects of the present invention was devised in view of the problems as described above, and provides a knock detection device capable of improving knock determination accuracy in an engine having a cam structure with a roller. It is to be. It should be noted that the present invention is not limited to this purpose, and is a function and effect derived from each configuration shown in the embodiment for carrying out the invention described later, and can also provide a function and effect that cannot be obtained by conventional techniques. Can be positioned as

(1) A knock detection device disclosed herein includes a valve-operated mechanism of a cam structure with a roller having a cam lobe for converting a rotational movement of a cam shaft into a reciprocating movement of a driven member, and a roller supported by the cam lobe. The engine knock detection device.
The knock detection device includes detection means for detecting vibrations of the engine, and storage means for storing a crank angle range in which a contact point with the driven member moves from one of the roller and the cam lobe to the other. Prepare. In addition, a determination unit that determines the presence or absence of knocking of the engine based on the magnitude of the vibration detected by the detection unit is provided. Further, the determination unit determines that the vibration detected by the detection unit is detected within the crank angle range as a condition for stopping the knock determination.

  For example, when the vibration detected by the detection means is within the crank angle range, in principle, it is preferable to exclude the vibration from the knock determination target and stop the knock determination. That is, it is preferable that the vibration included in the “transfer range” in which the contact point with the driven member moves from one of the roller and the cam lobe to the other is excluded from the knock determination target.

However, this does not mean that the determination of the knock by the determination unit is always prohibited when the vibration detected by the detection unit is within the crank angle range. On the other hand, when the vibration detected by the detection means is outside the crank angle range, it is preferable to determine the presence or absence of knocking based on the magnitude of the vibration.
Here, the “driven member” is a member that moves while being pressed by the cam lobe, and includes, for example, a valve tappet, a rocker member (rocker arm, swing arm), and the like.

  (2) Further, the determination unit determines that the vibration detected by the detection unit is detected at a period corresponding to the combustion cycle of the engine as a condition for stopping the knock determination. Is preferred. For example, the knock determination may be stopped when the vibration detected by the detection means is within the crank angle range and is detected at a period corresponding to the combustion cycle of the engine.

  (3) It is preferable that learning means for learning the crank angle range stored in the storage means is provided based on the vibration detected by the detection means. That is, it is preferable that the crank angle range stored in the storage unit is not a preset fixed range but a variable range that can be modified.

(4) Moreover, it is preferable that the learning means learns the crank angle range based on vibrations detected at a period corresponding to a combustion cycle of the engine among the vibrations detected by the detection means.
For example, when vibration is periodically detected at a crank timing corresponding to the combustion cycle of the engine, it is preferable to learn the vibration as “transfer vibration”. That is, it is preferable to exclude the vibration that is not synchronized with the combustion cycle of the engine from the learning target.

  (5) Moreover, it is preferable that the learning means learns the crank angle range when the engine load is less than a predetermined load. For example, it is preferable to learn the crank angle range when the intake air flow rate, the charging efficiency, the accelerator opening degree, and the like of the engine are below predetermined values. The smaller the engine load, the less likely knocking occurs.

  (6) Moreover, it is preferable that the learning means learns the crank angle range when the rotational speed of the engine is less than a predetermined speed. For example, it is preferable to learn the crank angle range when the rotational speed of the crankshaft of the engine, the rotational speed of the camshaft, or the like is equal to or less than a predetermined value. In addition, the detection accuracy of the vibration in the detection unit and the learning accuracy of the crank angle range stored in the storage unit are improved as the rotational speed of the engine is smaller.

  (7) In addition, phase control means for controlling the opening / closing phase of the valve of the valve mechanism is provided, and the determination means determines the presence or absence of the knock in consideration of the opening / closing phase controlled by the phase control means. It is preferable.

(8) Moreover, it is preferable that the said memory | storage means memorize | stores the waveform of the change vibration which arises when the contact with the said driven member moves from either one of the said roller and the said cam lobe to the other. In this case, it is preferable that the determination unit determines the presence or absence of the knock based on a waveform obtained by subtracting the waveform of the transfer vibration stored in the storage unit from the waveform of the vibration detected by the detection unit. .
That is, when a certain vibration is included in the transfer range, it is preferable not to completely exclude the vibration from the knock determination target, but to exclude only a portion corresponding to the transfer vibration from the knock determination target. .

  (9) Moreover, it is preferable that the said determination means determines the cylinder in combustion from the combustion cycle of the said engine, and determines the presence or absence of the said knock for every cylinder.

  According to the disclosed knock detection device, knock detection can be reduced by knock determination excluding the crank angle range in which vibration occurs due to transfer between the roller and the cam lobe. Thereby, the knocking determination accuracy can be improved, and further, the controllability and fuel consumption of the engine can be improved.

It is a figure which illustrates the block structure of the knock detection apparatus which concerns on one Embodiment, and the structure of the engine to which this knock detection apparatus was applied. It is a figure which illustrates the valve mechanism equipped with the engine, (a) is sectional drawing of a cam with a roller, and a tappet, (b) is an A direction arrow view (side view) of (a). It is a graph which shows the valve operating characteristic of the cam structure in an engine, (a) shows valve lift, (b) shows valve acceleration. It is a graph which concerns on the knock determination in a knock detection apparatus, (a) is a transfer vibration pattern, (b) illustrates the vibration pattern detected by the knock sensor. It is a map which illustrates the relationship between the driving | running state of an engine, and a learning area. It is a flowchart which illustrates the control procedure in a knock detection apparatus.

  Hereinafter, embodiments will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the present embodiment can be implemented with various modifications without departing from the spirit of the present embodiment, and can be selected or combined as necessary.

[1. Device configuration]
The knock detection device of the present embodiment is applied to the spark ignition type engine 10 shown in FIG. Here, one of a plurality of cylinders provided in the multi-cylinder engine 10 is shown. The cylinder head of the engine 10 is provided with an intake port 11 and an exhaust port 12, and an intake valve and an exhaust valve are provided at the opening end of each port 11, 12 on the cylinder side. Hereinafter, these intake valves and exhaust valves are collectively referred to as a valve 13. An intake passage 23 (intake manifold, intake pipe, etc.) is connected to the upstream side of the intake port 11, and an exhaust passage 24 (exhaust manifold, exhaust pipe, etc.) is connected to the downstream side of the exhaust port 12.

  A spark plug 14 is provided at the top of the cylinder with its tip protruding toward the cylinder. An injector 15 for injecting fuel is provided in the intake port 11. The ignition timing by the spark plug 14 and the amount of fuel injected from the injector 15 are controlled by the engine control device 1 described later.

  A DOHC (Double Over Head Camshaft) type valve operating mechanism for controlling the operation of each valve 13 is provided at the upper part of the cylinder head. This valve operating mechanism is a valve operating mechanism having a cam structure with a roller. As shown in FIGS. 2A and 2B, a cam lobe 18 fixed to a hollow cylindrical cam shaft 17 and a cam lobe. 18 and a roller 20 supported by the shaft 18. The driven member driven by the cam structure of the present embodiment is a tappet 16 that is attached to the upper end portion of the valve 13, but instead of the tappet 16, the upper end portion of the valve 13 is swung vertically. It is good also as a valve operating mechanism using arm members, such as a rocker arm to be made and a swing arm.

The cam lobe 18 is a plate-like member that converts the rotational movement of the camshaft 17 into the reciprocating movement of the tappet 16 and the valve 13. The profile of the cam lobe 18 is substantially oval, and is a shape in which a disc-shaped base circle portion 18a and a valve lift portion 18b formed by partially bulging the outer edge of the base circle portion 18a in the diameter increasing direction are formed integrally. have. In addition, on the tip side of the valve lift portion 18b, there is provided a notch portion in which an intermediate portion in the plate thickness direction is missing toward the base circle portion 18a side, and the roller 20 is centered on the shaft 21 therein. It is pivotally supported. The rotation axis C ₂ of the shaft 21 (that is, the rotation axis of the roller 20) is disposed in parallel with the rotation axis C ₁ of the cam shaft 17 (that is, the rotation axis of the cam lobe 18).

The position where the roller 20 is pivotally supported when the cam lobe 18 is viewed in the direction of the rotation axis C ₁ of the camshaft 17 is set such that the contour of the roller 20 protrudes outward from the contour on the tip side of the cam lobe 18. . Further, the radius of the base circle portion 18a, the valve 13 is set slightly smaller than the distance from the upper surface of the tappet 16 when it is closed to the rotational axis C ₁ of the camshaft 17. Thus, for example, the valve lift portion 18b is in a state which is located above the rotation axis C _1, a gap is formed between the base circle portion 18a and the tappet 16, the tappet 16 and the cam lobes 18 are not in contact.

  As a result, the valve 13 receives the urging force of the spring 22 and is pressed upward, and the closed state of the valve 13 is maintained. On the other hand, when the cam lobe 18 rotates and the valve lift 18b and the tappet 16 start to contact each other, the tappet 16 is pressed downward and the valve 13 starts to be opened. The details of the opening / closing operation of the valve 13 by the cam structure of this embodiment will be described later.

  The valve mechanism of the engine 10 is provided with a variable valve device 19 (phase control means) having a VVT (Variable Valve Timing) function for individually changing the opening / closing timing of each valve 13 of the intake / exhaust system. The The variable valve gear 19 has a function of changing the rotation phase of the camshaft 17 or the cam lobe 18 with respect to the rotation phase of the crankshaft of the engine 10, that is, a function of controlling the opening / closing phase of the valve 13.

Hereinafter, the amount of change in the rotation angle that indicates how much the actual rotation angle of the camshaft 17 from the reference rotation angle of the camshaft 17 is advanced or retarded is referred to as a phase angle θ _VVT . This phase angle θ _VVT is a parameter corresponding to the control amount of the valve timing. Information on the phase angle θ _VVT controlled by the variable valve gear 19 is transmitted to the engine control device 1 as needed.

  As shown in FIG. 1, a knock sensor 25 (detection means) that detects vibration of the engine 10 is attached to the outer surface of the cylinder block of the engine 10. The knock sensor 25 is, for example, a non-resonant acceleration sensor that outputs an electrical signal corresponding to the deformation amount of the piezoelectric element, and detects the acceleration K of vibration of the cylinder block. Information on the acceleration K detected here is transmitted to the engine control device 1.

  Further, as other sensors for acquiring information corresponding to the operating state of the engine 10, a crank angle sensor 26, an air flow sensor 27, an accelerator opening sensor 28, and the like are provided. The crank angle sensor 26 obtains the angle (crank angle θ) of the crankshaft of the engine 10 and its rotational speed Ne, and the air flow sensor 27 detects the intake flow rate Q passing through the intake passage 23. . The accelerator opening sensor 28 detects the amount of depression of the accelerator pedal by the driver as the accelerator opening A. Information on the crank angle θ, the rotational speed Ne, the intake air flow rate Q, and the accelerator opening A is transmitted to the engine control device 1. The information on the intake flow rate Q and the accelerator opening A is handled as parameters corresponding to the load of the engine 10.

[2. Operation of cam structure]
3A and 3B show the rotation angle of the camshaft 17 in a state where the phase angle θ _VVT in the variable valve gear 19 is zero (the state in which the valve 13 is driven at a standard valve timing). It is a graph which illustrates the relationship between the valve lift amount and acceleration of the valve 13 with respect to. For example, the boundary of the process of the valve lift portion 18b is moved from the upper side of the rotating shaft C ₁ downward side, the the cam lobe 18 and the tappet 16 first contacts includes a base circle portion 18a and a valve lift portion 18b It is a neighborhood.

  When the cam lobe 18 and the tappet 16 come into contact with each other, the tappet 16 is pressed downward by the valve lift portion 18b of the cam lobe 18 and the valve lift amount starts to increase. Subsequently, as the cam lobe 18 rotates, the tappet 16 descends and the valve lift amount increases. As a result, the acceleration of the valve 13 rapidly increases, and an acceleration peak indicated by symbol P1 in FIG. 3B is generated. The graph shape of the acceleration peak P1 is a smooth curved shape corresponding to the profile shape of the valve lift portion 18b, and vibrations having a magnitude that can be detected by, for example, the knock sensor 25 hardly occur.

  When the cam lobe 18 further rotates, both the valve lift portion 18b and the roller 20 come into contact with the tappet 16, and an acceleration peak indicated by P2 in FIG. 3 occurs. The graph shape of the acceleration peak P2 is a curved shape having a slightly discontinuous tendency due to the collision between the roller 20 and the tappet 16, and can generate a vibration having a magnitude that can be detected by the knock sensor 25. .

Subsequently, the valve lift portion 18 b is separated from the surface of the tappet 16, and only the roller 20 is in contact with the tappet 16. At this time, the acceleration of the valve 13 becomes a negative value, and the moving speed of the valve 13 gradually decreases. Further, when the cam lobe 18 is rotated until the normal line of the tappet 16 at the contact portion with the roller 20 passes through the rotation axis C ₂ of the shaft 21, the valve lift amount of the valve 13 is maximized. Thereafter, the valve lift amount gradually decreases, and acceleration peaks similar to the above two acceleration peaks P1 and P2 occur in the reverse order.

  That is, when both the valve lift 18b and the roller 20 come into contact with the tappet 16 again, an acceleration peak indicated by P3 in FIG. 3 occurs. The acceleration peak P3 is caused by the collision between the valve lift portion 18b and the tappet 16, and can generate a vibration having a magnitude that can be detected by the knock sensor 25 in the same manner as the acceleration peak P2.

  Thereafter, the roller 20 is separated from the surface of the tappet 16, and only the valve lift portion 18 b comes into contact with the tappet 16. At this time, the valve lift amount decreases according to the profile shape of the valve lift portion 18b, and the acceleration peak P4 associated therewith occurs. Further, as the valve lift amount gradually approaches zero, the acceleration of the valve 13 converges toward zero. The acceleration peak P4 varies in a smooth curve like the acceleration peak P1. Therefore, at this time, vibration of a magnitude that can be detected by the knock sensor 25 hardly occurs.

  The camshaft 17 has a plurality of cam lobes 18 that drive a plurality of valves of a plurality of cylinders, but the positional accuracy of the valve lift portions 18b of the individual cam lobes 18 and the rollers 20 are strictly different. For this reason, the acceleration peaks P1 to P4 are different for each cylinder and each cam lobe 18 depending on the positional accuracy of the valve lift 18b and the roller 20.

[3. Engine control unit]
As shown in FIG. 1, an engine control device 1 is provided in the engine 10 of the present embodiment. The engine control apparatus 1 is configured as, for example, an LSI device or an embedded electronic device in which a microprocessor, a CPU, a ROM, a RAM, and the like are integrated. The engine control device 1 is an electronic control unit (ECU) that comprehensively controls a wide range of systems such as an ignition system, a fuel system, an intake / exhaust system, and a valve system related to the engine 10, and is supplied to each cylinder of the engine 10. Controls the amount of air to be injected, the amount of fuel injection, the ignition timing of each cylinder, etc.

  In the engine control apparatus 1 of the present embodiment, knock control is performed for controlling the operating state of the engine 10 while suppressing the occurrence of knock. In this knock control, based on the information on the acceleration K detected by the knock sensor 25, it is determined whether or not the vibration of the frequency derived from the knock of the engine 10 has occurred, that is, the presence or absence of the knock is determined. Such a determination is performed for each cylinder of the engine 10. Further, when it is determined that knocking has occurred, the ignition timing at the spark plug 14 of the cylinder is controlled in the retard direction, and when it is determined that knocking has not occurred, knocking occurs again. The ignition timing is controlled in the advance direction to such an extent that it does not occur. By such control, an ignition timing at which good output efficiency can be obtained is set within an ignition timing range in which excessive knock does not occur.

  By the way, the engine 10 is an engine 10 having a valve operating mechanism having a cam structure with a roller, and can be detected by a knock sensor 25 as indicated by reference numerals P2 and P3 in FIG. A large amount of vibration can occur. That is, when the member to be contacted by the tappet 16 is changed from one of the valve lift portion 18b and the roller 20 to the other, the engine 10 slightly vibrates, and it is determined that this vibration is erroneously caused by knocking. There is a possibility that. The engine control apparatus 1 of the present embodiment performs knock control and learning control for preventing such erroneous determination of knock. Hereinafter, the vibration generated when the tappet 16 collides with the valve lift portion 18b and the roller 20 is referred to as “transfer vibration”.

  As shown in FIG. 1, the engine control device 1 includes a storage unit 2, a learning unit 3, a knock determination unit 4, and an ignition timing control unit 5. Various functions included in each of these elements may be realized by an electronic circuit (hardware), may be programmed as software, or some of these functions may be provided as hardware, The other part may be software.

The storage unit 2 (storage unit) stores information related to transfer vibration, and includes a crank angle range storage unit 2a and a vibration waveform storage unit 2b.
The crank angle range storage unit 2a stores the timing (period) at which transfer vibration occurs for each cylinder. Here, the range of the crank angle θ in which the contact point with the tappet 16 moves from one of the valve lift portion 18b of the cam lobe 18 and the roller 20 to the other is stored as the “transfer range”.

This change range includes the crank angle at the moment when both the valve lift portion 18b and the roller 20 come into contact with the tappet 16 (the crank angle corresponding to the time at which change vibration occurs). In this embodiment, information on the acceleration K corresponding to the transfer vibration is measured in advance through tests and experiments. For example, the acceleration of the valve 13 is greater than or equal to a predetermined value for each of the acceleration peaks P2 and P3 in FIG. The crank angle θ range (θ ₁ ≦ θ ≦ θ ₂ , θ ₃ ≦ θ ≦ θ ₄ ) is stored for each cylinder and each cam lobe 18 in the crank angle range storage unit 2a as a transfer range. However, the “change range data based on the acceleration measured in advance” here is data as an initial value, and can be changed, modified, and updated by learning control described later.

  Various setting of the transfer range can be considered according to the type of the engine 10 or the variable valve gear 19. For example, in the case of the engine 10 in which one intake valve and one exhaust valve are provided for each cylinder, two periods corresponding to the switching vibration of each valve may be set. On the other hand, in the engine 10 having a plurality of intake valves in one cylinder, when the opening / closing timings of the intake valves are different, a period corresponding to the switching vibration for each valve may be set.

The vibration waveform storage unit 2b stores a waveform of transfer vibration for each cylinder. Here, the waveform of the acceleration K (the waveform of the acceleration K of the engine block vibration) with the transfer range stored in the crank angle range storage unit 2a as a defined area is stored. For example, as shown in FIG. 4A, a vibration waveform of the acceleration K in θ ₁ ≦ θ ≦ θ ₂ that is one of the transfer ranges is stored. Similarly, the vibration waveform of the acceleration K with θ ₃ ≦ θ ≦ θ ₄ is also stored. The vibration waveform of the acceleration K stored here corresponds to each of the aforementioned acceleration peaks P2 and P3.

  The learning unit 3 (learning unit) corrects the information stored in the storage unit 2 for each cylinder and changes the information to the information according to the actual situation by learning based on the information of the acceleration K detected by the knock sensor 25. Is. Here, both the transfer range stored in the crank angle range storage unit 2a and the vibration waveform of the acceleration K stored in the vibration waveform storage unit 2b are targeted for learning. The learning unit 3 includes a learning condition determination unit 3a and a transfer vibration learning unit 3b.

The learning condition determination unit 3a determines the operating state of the engine 10 for learning. Here, for example, it is determined whether or not all the following conditions are satisfied.
Learning conditions The rotational speed Ne of the engine 10 is a predetermined speed Ne ₀ or less. 2. The load of the engine 10 is below a predetermined value. Within (or near) the transfer range in the previous combustion cycle
Acceleration K similar to the current combustion cycle is detected

Various methods for determining the magnitude of the load related to the learning condition 2 can be considered. For example, when the intake air flow rate Q is less than or equal to a predetermined amount, or when the charging efficiency Ec calculated based on the intake air flow rate Q is less than or equal to a predetermined value, the accelerator opening A detected by the accelerator opening sensor 28 is predetermined open. in such case time a is ₀ or less, the learning condition 2 may be satisfied. In the present embodiment, as shown in FIG. 5, the operating state of the engine 10 enters a learning region indicated by hatching in the drawing using a map in which the correspondence relationship between the rotational speed Ne of the engine 10 and the load is defined. The learning conditions 1 and 2 are both satisfied.

  Further, the learning condition 3 is a condition for confirming whether or not the information of the acceleration K to be learned corresponds to the transfer vibration. Since the transfer vibration is periodically generated in a cycle corresponding to the combustion cycle of the engine 10 (corresponding to the rotation angle of the camshaft 17), the periodicity is recognized within the transfer range (or in the vicinity thereof). Only information on the acceleration K to be learned is the learning target. When all of the learning conditions 1 to 3 are satisfied, the learning condition determination unit 3a determines that the operating state of the engine 10 is a state suitable for learning.

  The transfer vibration learning unit 3b, based on the information on the acceleration K transmitted from the knock sensor 25, when the learning condition determination unit 3a determines that the learning conditions 1 to 3 are both established, the vibration of the transfer range and the acceleration K. Learning with the waveform is performed. Here, learning control is performed to reflect the information measured up to that point in the information stored in the storage unit 2.

  For example, actual measurement information of the acceleration K corresponding to the acceleration peaks P2 and P3 is extracted from the information of the acceleration K detected in the immediately preceding combustion cycle, and the actual measurement range of the crank angle θ in which the acceleration K is equal to or greater than a predetermined value. Is calculated. And the correction calculation which brings the transfer range memorize | stored in the crank angle range memory | storage part 2a close to an actual measurement range is implemented. Further, a correction calculation is performed to bring the vibration waveform of the acceleration K stored in the vibration waveform storage unit 2b closer to the vibration waveform of the actually measured information. As a result, the operating environment of the engine 10 and the characteristics of transfer vibration due to secular change can be accurately grasped.

The knock determination unit 4 (determination means) determines the presence or absence of knock for each cylinder based on the information on the acceleration K detected by the knock sensor 25. In principle, knock determination unit 4 excludes the information on acceleration K within the transfer range stored in crank angle range storage unit 2a from the knock determination. However, since the information on the acceleration K that should be excluded from the knock determination is the information on the acceleration K corresponding to the transfer vibration, if the large vibration is detected continuously (periodically) at the same crank timing, the large information Vibration will be excluded from knock determination. Further, when the phase angle theta _VVT which is controlled by the variable valve device 19 is not zero, since the crank angle occurring transit vibration theta is varied by the amount of phase angle theta _VVT, considering the phase angle theta _VVT Then, the threshold value of the crank angle θ excluded from the knock determination is calculated.

The knock determination unit 4 of the present embodiment determines that a knock has occurred, for example, when any of the following determination conditions 1 and 2 is satisfied and the determination condition 3 is satisfied.
Judgment conditions 1. The part for which the acceleration K is judged is within the transfer range of the cylinder.
(Θ ₁ ≦ θ ≦ θ ₂ , θ ₃ ≦ θ ≦ θ ₄ ) 2. The part for which the acceleration K is determined does not show periodic vibration. The magnitude of the acceleration K to be judged is greater than or equal to the predetermined value K ₀

When the determination conditions 1 to 3 are determined in real time, instead of the determination condition 1, “the crank angle θ at that time is not θ ₁ ≦ θ ≦ θ ₂ and θ ₃ ≦ θ ≦ θ ₄ is not satisfied. It may be determined. For example, the detection signal of the knock sensor 25 when the crank angle θ of the engine 10 is θ ₁ ≦ θ ≦ θ ₂ or θ ₃ ≦ θ ≦ θ ₄ is invalidated, and the magnitude of the acceleration K obtained from the effective detection signal There when the predetermined value K ₀ or more, it is conceivable to determine that knocking has occurred. Further, when the crank angle θ of the engine 10 is θ ₁ ≦ θ ≦ θ ₂ or θ ₃ ≦ θ ≦ θ ₄ , the acceleration K suddenly occurs with reference to the change in the acceleration K in the transfer range in the previous combustion cycle. When it becomes large (when there is no periodicity synchronized with the combustion cycle), it may be determined that knocking has occurred.

The cylinders subject to knock determination may be all cylinders of the engine 10. Alternatively, only the cylinders whose peak value of acceleration K is equal to or greater than a predetermined value may be determined. Which cylinder is in combustion can be identified by a crank angle θ and a signal from the ignition timing control unit 5. The knock determination unit 4 determines how many cylinders the detected acceleration K is, for example, the acceleration K of the first cylinder is K ₁ , the acceleration K of the second cylinder is K _2, etc., and the acceleration K is The generated crank angle θ and the cylinder number may be stored in the crank angle range storage unit 2a. Further, when two cam lobes 18 having different phases are provided in each cylinder and the opening and closing timing of the valve 13 is shifted to generate a tumble flow in the cylinder, for example, the cam lobe 18 on the front side of the first cylinder of each cam lobe 18 is provided. The acceleration K may be stored as K _1-F , and the rear side may be stored as K _1-R .

Information on the presence or absence of knocking determined here is transmitted to the ignition timing control unit 5. The acceleration K measured by the knock sensor 25 may be used as it is as the determination target acceleration K in the determination condition 3, or the transfer stored in the vibration waveform storage unit 2b from the waveform of the acceleration K may be used. You may use what subtracted the waveform of vibration. That is, it may be determined that knocking has occurred when the magnitude of the acceleration K is equal to or greater than the predetermined value K ₀ after subtracting the waveform of the transfer vibration from the actually measured vibration waveform.

  When the knock determination unit 4 determines that a knock has occurred, the ignition timing control unit 5 performs a retard control for moving the ignition timing at the spark plug 14 for the cylinder in the retard direction. . In addition, the ignition timing control unit 5 performs advance angle control that gradually moves the ignition timing in the advance direction when knocking does not occur by controlling the ignition timing in the retard direction. Since the presence or absence of knocking is determined for each cylinder, the retard angle control and the advance angle control are also performed for each cylinder.

  The amount of movement of the ignition timing (retard amount, advance amount) in the retard angle control and the advance angle control corresponds to the absolute value of the acceleration K when the knock determination unit 4 determines that the knock has occurred, for example. Alternatively, it may be a predetermined value set in advance according to the rotational speed Ne of the engine 10 at that time and the magnitude of the load.

[4. flowchart]
FIG. 6 is a flowchart illustrating the procedure of knock control performed by the engine control apparatus 1. This flow is repeatedly performed for each cylinder at a preset cycle. The flow related to knock control is mainly steps A10 to A80, and the flow related to learning control is mainly steps A40 and A90 to A100.

  In step A10, information such as the rotational speed Ne of the engine 10, the crank angle θ, the intake flow rate Q, and the accelerator opening A detected by each of the crank angle sensor 26, the airflow sensor 27, and the accelerator opening sensor 28 is stored in the engine control device. 1 is input. In step A20, information on the acceleration K detected by the knock sensor 25 is input to the engine control apparatus 1.

In the subsequent step A30, the knock determination unit 4 determines whether or not the crank angle θ at that time is within the transfer range (whether θ ₁ ≦ θ ≦ θ ₂ or θ ₃ ≦ θ ≦ θ ₄ ). Is done. The determination at this step corresponds to the above-described determination condition 1. Here, when the crank angle θ is not within the transfer range, the routine proceeds to step A60 where normal knock determination is performed. On the other hand, when this condition is satisfied, the process proceeds to Step A40.

When the variable valve gear 19 controls the phase angle θ _VVT to a value other than zero, the change range stored in the crank angle range storage unit 2a and the acceleration K detected by the knock sensor 25 are used. The corresponding crank angle θ should be different by the phase angle θ _VVT . Therefore, in the determination of the crank angle θ in step A30, it is preferable to determine whether or not the crank angle θ is within the transfer range in consideration of the shift of the phase angle θ _VVT .

  As described above, the camshaft 17 has a plurality of cam lobes 18 that drive a plurality of valves of a plurality of cylinders, but the positional accuracy of the valve lift portions 18b of the individual cam lobes 18 and the rollers 20 are strictly different. Further, the level of transfer vibration generated in each cylinder is different for each cylinder. Therefore, in step A30, it is determined which number cylinder is the target, or what number is the change position of the cam lobe 18, and the crank angle θ for the target cylinder or cam lobe 18 is within the transfer range. It is determined whether or not.

In Step A40, it is determined whether or not the same acceleration K is detected in the transfer range in the previous combustion cycle. The determination in this step is a determination for determining whether or not the vibration is generated in a cycle corresponding to the determination condition 2 and corresponding to the combustion cycle of the engine 10. Here, when the same acceleration K is detected at the same crank timing in the previous combustion cycle, the routine proceeds to step A50 where the knock determination is prohibited, and then the routine proceeds to step A90. That is, of the acceleration K detected within the transfer range (θ ₁ ≦ θ ≦ θ ₂ , θ ₃ ≦ θ ≦ θ ₄ ), the vibration having periodicity synchronized with the combustion cycle is determined as the transfer vibration. And excluded from knock determination. Thereby, the knocking determination accuracy is improved. On the other hand, when the condition of step A40 is not satisfied, the routine proceeds to step A60, where normal knock determination is performed.

At this time, knock determination may be prohibited for each cylinder identified in step A30. For example, knock determination may be prohibited only for a cylinder having the highest acceleration K at the time of transfer. As a result, it is possible to prevent “when the crank angle θ excluding knock determination increases, the range in which the original knock determination can be performed is excessively limited”.
Further, the crank angle (θ ₁ ≦ θ ≦ θ ₂ , θ ₃ ≦ θ ≦ θ ₄ ) of the transfer range may be changed for each cylinder. According to the positional accuracy of the valve lift 18b and the roller 20 of the cam lobe 18 of each cylinder, it is possible to appropriately overcome the vibration and improve the knock determination accuracy.

In step A60, the knock determination unit 4 determines whether or not the engine 10 has been knocked. Here, for example, whether the magnitude of the acceleration K is observed a predetermined value K ₀ or more vibration is determined. The determination in this step corresponds to the above-described determination condition 3. Here, if the acceleration K is equal to or greater than the predetermined value K _0, it is determined that knocking has occurred, and the process proceeds to step A 70. On the other hand, if the acceleration K is less than the predetermined value K _0, it is determined that no knock has occurred, and the process proceeds to step A80.

In step A60, the vibration waveform of acceleration K (indicated by a solid line in FIG. 4B) is subtracted from the waveform of the transfer vibration stored in the vibration waveform storage unit 2b [broken line in FIG. 4B. It may be determined whether or not a knock has occurred based on this. That is, if the peak value of the vibration waveform obtained by subtracting the transfer vibration from the actually measured vibration is equal to or greater than the predetermined value K ₀ , it may be determined that knocking has occurred almost simultaneously with the transfer vibration.

  In step A70, the ignition timing control unit 5 performs retard angle control. Here, the ignition timing at the spark plug 14 is controlled in the retard direction. As a result, knocking is less likely to occur in subsequent combustion cycles. On the other hand, in step A80, the ignition timing control unit 5 performs the advance angle control, and the ignition timing is controlled in the advance direction. This advance angle control functions to reduce the retard amount by retard angle control (return the ignition timing). For example, when the retard control is performed in the previous calculation cycle and knocking does not occur, the ignition timing is gradually advanced. In addition, when the retard control has not been performed so far, the advance control need not be performed. After executing the above steps A70 and A80, this flow is finished as it is.

  In step A90, the learning condition determination unit 3a determines whether or not the operating state of the engine 10 is within the learning region. The determination in this step corresponds to the learning condition 1 and the learning condition 2 described above. Here, when the operation state of the engine 10 is outside the learning region, this flow is finished as it is. Further, it is determined that the learning condition 3 has already been established in step A40. If the condition in step A90 is established, the process proceeds to step A100.

In step A100, the transfer vibration learning unit 3b learns the transfer range and the vibration waveform of the acceleration K. As a result, the measurement information is reflected in the threshold values θ ₁ , θ ₂ , θ ₃ , and θ ₄ of the transfer range stored in the storage unit 2 and the vibration waveform of the acceleration K corresponding to the actual transfer vibration is learned. The Note that when the variable valve operating device 19 controls the phase angle θ _VVT to a value other than zero, learning is performed in consideration of the deviation of the phase angle θ _VVT .

[5. Action, effect]
(1) With such control, in the knock control in the engine control apparatus 1 described above, the range of the crank angle θ in which the change vibration occurs is stored as the “change range” and, in principle, detected within the change range. Vibration is excluded from knock determination. As a result, the knock determination unit 4 does not mistake the transfer vibration for knocking, that is, it is possible to reduce knock detection errors and improve the knock determination accuracy. In addition, since knock detection errors are reduced, the controllability and fuel consumption of the engine 10 can be improved.

  (2) Further, in the knock control described above, it is determined whether or not the vibration detected in the transfer range is a vibration having periodicity corresponding to the combustion cycle of the engine 10. As a result, it is possible to accurately determine whether or not the vibration detected within the transfer range is a transfer vibration, and the discrimination accuracy between the transfer vibration and the knock vibration can be improved. Therefore, knock detection errors can be reduced, and knock determination accuracy can be improved.

  (3) Further, in the engine control apparatus 1 described above, the transfer range stored in the crank angle range storage unit 2a is learned based on the information on the measured vibration acceleration K, and updated to information in accordance with the actual situation. The As a result, it is possible to accurately grasp changes in the characteristics of the transfer vibration due to the operating environment of the engine 10 and changes over time, further reduce knock detection errors, and improve knock detection accuracy.

  (4) Further, in the engine control apparatus 1 described above, vibrations periodically generated in a cycle corresponding to the combustion cycle of the engine 10 among vibrations detected by the knock sensor 25 are regarded as “transfer vibrations”. Learning control based on the transfer vibration is performed. As described above, the control configuration in which the combustion cycle of the engine 10 is associated with the vibration generation cycle can increase the learning accuracy of the transfer range stored in the crank angle range storage unit 2a, and improve the knock detection accuracy. Can be made.

  (5) Further, regarding the execution conditions for such learning control, in the above-described engine control apparatus 1, as shown in FIG. 5, a low-load operation region where knocking is relatively difficult is set as the learning region. . Thereby, learning accuracy can be further improved and knock detection accuracy can be improved.

(6) Similarly, in the engine control apparatus 1, as shown in FIG. 5, an operation region where the rotation speed of the engine 10 is low is set as a learning region. The detection accuracy of the crank angle θ in the crank angle sensor 26 is improved as the rotational speed of the engine 10 is lower. Therefore, the values of the transfer range threshold values θ ₁ , θ ₂ , θ ₃ , and θ ₄ can be made more accurate, and the knock detection accuracy can be improved.

(7) In the engine control apparatus 1 described above, the threshold value of the crank angle θ to be excluded from the knock determination is calculated in consideration of the phase angle θ _VVT controlled by the variable valve gear 19. For example, when the transfer range when the phase angle theta _VVT is zero is to "θ ₁ ≦ θ ≦ θ _2", transfer range when the phase angle theta _VVT is controlled theta _VVT1 is "θ ₁ -θ _VVT1 ≦ θ ≦ θ ₂ −θ _VVT1 ”. As described above, by changing the knock determination condition according to the phase angle θ _VVT , it is possible to accurately detect the knock regardless of the operating state of the variable valve device 19 and the magnitude of the phase angle θ _VVT .

  (8) Further, in the engine control apparatus 1 described above, as shown in FIG. 4 (b), a value obtained by subtracting the waveform of the transfer vibration from the vibration waveform of the acceleration K is calculated, and whether or not a knock has occurred based on this calculation. It is also possible to determine whether or not. According to such a method, even when a knock occurs almost simultaneously with the transfer vibration, the occurrence of the knock can be accurately detected. Therefore, the knock determination accuracy can be improved.

(9) In addition, the range of the crank angle θ excluded from the knock determination is set for each cylinder, and is individually learned in accordance with the transfer timing in each cylinder and the actually generated acceleration K. In this way, by adjusting the masking timing for each cylinder, the range in which knock control is performed can be expanded as much as possible, and the detection accuracy of knock can be increased.
Further, when cam lobes 18 having different rotational phases are provided in the same cylinder, the detection accuracy of knocking can be improved by excluding the transfer range for each cam lobe 18 from the knock determination.

  (10) If the control configuration is such that the acceleration K at the time of transfer is detected for each cylinder and the knock determination is prohibited only in the cylinder having the highest acceleration K, the knock does not actually occur. Only the suspicious cylinders can be selectively determined, and the knock determination exclusion area can be reduced. Thereby, the knock determination accuracy in the engine 10 as a whole can be improved.

[6. Modified example]
The above-described embodiment can be implemented with various modifications without departing from the gist thereof, and each configuration of the above-described embodiment may be selected or combined as appropriate.
For example, although the engine 10 provided with the knock sensor 25 is illustrated in the above-described embodiment, the means for detecting the vibration of the engine 10 is not limited to this. It is only necessary to provide a sensor that detects displacement, speed, acceleration, and the like of vibrations acting on at least the cylinder block and cylinder head of the engine 10. In this case, a control configuration may be employed in which displacement information, speed information, acceleration information, and the like corresponding to the vibration of the engine 10 are calculated inside the engine control device 1 based on the detection signal transmitted from the sensor. That is, the means for detecting the vibration of the engine 10 may be software.

  In the knock control of the above-described embodiment, when the knock occurs, the ignition timing at the spark plug 14 is controlled in the retard direction, and when the knock does not occur, the ignition timing is controlled in the advance direction. The specific control method is not limited to this, and various control methods can be considered, and a control method in known knock control can be applied.

  In addition, the crank angle range storage unit 2a of the above-described embodiment stores the range of the crank angle θ in which the transfer vibration is generated as the transfer range, but instead of the crank angle θ, the camshaft rotation angle and time range are stored. It may be memorized. If at least the parameter range correlated with the timing of occurrence of transfer vibration is stored, it is possible to discriminate between actually measured vibration and transfer vibration.

  Further, in the above-described embodiment, the waveform of the acceleration K of the transfer vibration is stored in the vibration waveform storage unit 2b. However, the vibration waveform stored here is not limited to the acceleration K waveform. For example, vibration displacement and velocity waveforms may be stored. The vibration waveform stored in the vibration waveform storage unit 2b is information for excluding the transfer vibration from the actual measurement value of the acceleration K for determining the presence or absence of knocking. It is preferable to store a waveform for a parameter to be determined.

  In the above-described embodiment, the knock detection device applied to the spark ignition type engine 10 (for example, a gasoline engine) is shown, but other types and types of internal combustion engines (for example, diesel engines) are used instead of the engine 10. It is also possible to apply to. Therefore, the types of knocks that can be determined by the engine control apparatus 1 of the present embodiment include not only high-speed knocks (knocks that occur in a high rotation range) and low-speed knocks (knocks that occur in a low rotation range), but also diesel knocks, etc. Can also be mentioned.

DESCRIPTION OF SYMBOLS 1 Engine control apparatus 2 Memory | storage part (memory | storage means)
3 learning part (learning means)
4 knock determination unit (determination means)
DESCRIPTION OF SYMBOLS 5 Ignition timing control part 10 Engine 14 Spark plug 16 Tappet 18 Cam lobe 18a Base circle part 18b Valve lift part 19 Variable valve apparatus (phase control means, valve mechanism)
20 roller 25 knock sensor (detection means)
26 Crank angle sensor

Claims (9)

A knock detection device for an engine, comprising: a cam lobe having a cam structure with a roller having a cam lobe for converting the rotational motion of the cam shaft into a reciprocating motion of a driven member; and a roller pivotally supported by the cam lobe.
Detecting means for detecting vibrations of the engine;
Storage means for storing a crank angle range in which a contact point with the driven member moves from one of the roller and the cam lobe to the other;
Determination means for determining the presence or absence of knocking of the engine based on the magnitude of the vibration detected by the detection means,
The knock detection apparatus according to claim 1, wherein the determination unit determines that the vibration detected by the detection unit is detected within the crank angle range as a condition for stopping the determination of the knock. The determination unit determines that the vibration detected by the detection unit is detected at a period corresponding to a combustion cycle of the engine as a condition for stopping the determination of the knock. The knock detection device according to claim 1. The knock detection device according to claim 1 or 2, further comprising learning means for learning the crank angle range stored in the storage means based on the vibration detected by the detection means. The learning means learns the crank angle range based on vibrations detected at a period corresponding to a combustion cycle of the engine among the vibrations detected by the detection means. The knock detection device according to the description. The knock detection device according to claim 3 or 4, wherein the learning means learns the crank angle range when a load of the engine is less than a predetermined load. The knock detection device according to any one of claims 3 to 5, wherein the learning means learns the crank angle range when a rotation speed of the engine is less than a predetermined speed. Phase control means for controlling the opening and closing phase of the valve of the valve mechanism,
The knock detection device according to claim 1, wherein the determination unit determines the presence or absence of the knock in consideration of the opening / closing phase controlled by the phase control unit. The storage means stores a waveform of a transfer vibration generated when a contact point with the driven member moves from one of the roller and the cam lobe to the other,
The determination means determines the presence or absence of the knock based on a waveform obtained by subtracting the waveform of the transfer vibration stored in the storage means from the vibration waveform detected by the detection means, The knock detection device according to any one of claims 1 to 7. The knock according to any one of claims 1 to 8, wherein the determination means determines a cylinder in combustion from a combustion cycle of the engine and determines the presence or absence of the knock for each cylinder. Detection device.

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