JP2008309166A - Malfunction detecting device for variable valve timing mechanism for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To normally determine the deterioration of operating oil and the malfunction of a VVT itself, separately. <P>SOLUTION: The malfunction detecting device comprises a malfunction determining means for a VVT mechanism for changing valve operating characteristics including at least one of a valve timing, a valve lift amount and a valve opening period for one or both of an intake valve and an exhaust valve of an engine, and an actuator for changing the valve operating characteristics of the VVT mechanism. The determining means calculates the first response speed of the VVT mechanism when the oil temperature of operating oil to drive the actuator is in a first range, erects a first malfunction determination flag when the first response speed is smaller than a malfunction determination value, calculates a second response speed of the VVT mechanism when the oil temperature of the operating oil is in a second range higher than the first range, erects a second malfunction determination flag when the second response speed is smaller than the malfunction determination value, and determines that the VVT mechanism is normal when both the first and second malfunction determination flags are not erected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an abnormality detection device for a variable valve timing mechanism of an internal combustion engine, and in particular, a valve including at least one of valve timing, valve lift amount, and valve opening period of one or both of an intake valve and an exhaust valve of the internal combustion engine. VVT of a variable valve timing mechanism (hereinafter referred to as “VVT” where appropriate) that changes the operating characteristics, when the temperature of the hydraulic oil that drives the actuator that drives the actuator is low, the hydraulic pressure is high, and the response of the VVT actuator is poor. The present invention relates to an abnormality detection device for a variable valve timing mechanism of an internal combustion engine that eliminates erroneous determination of abnormality.

  A variable valve timing (VVT) mechanism of an internal combustion engine (hereinafter referred to as an engine) is a valve timing (open / close valve timing) of one or both of an intake valve and an exhaust valve, a valve lift amount, and a valve opening period. It is a mechanism for changing the valve operating characteristics including at least one. Lubricating oil is stored in an oil pan provided at the lower part of the cylinder block of the engine. This lubricating oil is pumped out by an oil pump driven by the rotation of the engine, and is supplied to each part of the engine, an oil control valve (OCV), a VVT, and the like. Since the VVT actuator is driven by the oil pressure of the lubricating oil generated by the oil pump (hereinafter referred to as hydraulic oil as appropriate), the hydraulic oil pressure is low when the engine speed is low, and the driving force of the VVT actuator is reduced. However, the operation delay time increases.

  An abnormality detection device for a variable valve timing mechanism of an internal combustion engine according to a first prior art detects an operation delay time of the VVT, and determines that a VVT abnormality occurs when the detected operation delay time becomes larger than a reference value. . However, according to the first prior art, if the VVT abnormality determination is not prohibited when the engine speed is low but the VVT is normal, there is a possibility that the VVT abnormality is erroneously determined.

  In order to solve this problem, the abnormality detection device for a variable valve timing mechanism of an internal combustion engine described in Japanese Patent Application Laid-Open No. 7-127407 according to the second prior art determines whether to execute or prohibit VVT abnormality determination based on hydraulic pressure. . That is, the VVT abnormality determination is executed when the hydraulic oil pressure is high, and the VVT abnormality determination is prohibited when the hydraulic pressure is low. Here, the VVT abnormality determination is determined as a VVT abnormality when a deviation between a target valve timing determined according to the engine operating state and an actual valve timing measured during engine operation is more than a predetermined value. To do. However, according to the second prior art, when the oil pressure of the hydraulic oil is high, when the oil temperature is low, the viscosity of the hydraulic oil increases [decreased oil amount], and the VVT operates similarly when the oil pressure is low. Responsiveness deteriorates and operation delay time increases. For this reason, if the hydraulic pressure of the hydraulic oil is high and the oil temperature is low but the VVT is normal, there is a possibility that the VVT abnormality may be erroneously determined unless the VVT abnormality determination is prohibited.

  In order to solve this problem, an abnormality detection device for a variable valve timing mechanism of an internal combustion engine described in Japanese Patent Laid-Open No. 2000-73794 according to the third prior art determines VVT abnormality based on oil temperature. That is, when the oil temperature of the hydraulic oil is high, VVT abnormality determination is executed, and when the oil temperature is low, VVT abnormality determination is prohibited. However, according to the third prior art, when the oil temperature of the hydraulic oil is high and the oil pressure is low, the operation responsiveness of the VVT deteriorates and the operation delay time increases when the oil temperature is low. To do. Nevertheless, when the hydraulic oil temperature is high and the hydraulic pressure is low, the VVT may be erroneously determined to be normal.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an abnormality detection device for a variable valve timing mechanism of an internal combustion engine that makes a determination of a VVT abnormality without error and performs normality determination by dividing the abnormality of the VVT itself.

  An apparatus for detecting an abnormality of a variable valve timing mechanism of an internal combustion engine according to the present invention that achieves the above object comprises at least one of valve timing, valve lift amount, and valve opening period of one or both of an intake valve and an exhaust valve of the internal combustion engine. An abnormality detection device for a variable valve timing mechanism of an internal combustion engine, comprising: a determination unit that determines abnormality of a variable valve timing mechanism that changes a valve operation characteristic including an actuator that changes the valve operation characteristic of the variable valve timing mechanism. The determination unit calculates a viscosity of hydraulic fluid that drives the actuator, and a second calculation that calculates a reference response speed of the variable valve timing mechanism with respect to the viscosity calculated by the first calculation unit. And a duration during which the deviation is greater than the reference response speed after a predetermined time. When, characterized in that the variable valve timing mechanism provided with, and an abnormality judging means for judging as abnormal.

  In the abnormality detection apparatus for a variable valve timing mechanism of the internal combustion engine, the normality determining means is configured to provide oil for the variable valve timing mechanism when only the first abnormality determination flag is set and the second abnormality determination flag is not set. Is determined to be deteriorated.

  In the abnormality detection device for a variable valve timing mechanism of an internal combustion engine, the normality determination means determines that the variable valve timing mechanism is abnormal when the first abnormality determination flag and the second abnormality determination flag are standing together. To do.

  An abnormality detection device for a variable valve timing mechanism of an internal combustion engine according to another embodiment that achieves the above object is provided that includes at least one of valve timing, valve lift amount, and valve opening period of one or both of an intake valve and an exhaust valve of the internal combustion engine. An abnormality of a variable valve timing mechanism of an internal combustion engine, comprising: a determination unit that determines abnormality of a variable valve timing mechanism that changes a valve operation characteristic including one; and an actuator that changes the valve operation characteristic of the variable valve timing mechanism. In the detection device, the determination means is calculated by first calculation means for calculating a response speed of the variable valve timing mechanism, and by the first calculation means for an increase (ΔOT) in oil temperature of hydraulic oil that drives the actuator. In addition, the rate of change (ΔRV /) of the response speed increment (ΔRV) of the variable valve timing mechanism OT), second detecting means for calculating the change rate (ΔRV / ΔOT), detecting means for detecting the oil temperature when the oil temperature decreases as the oil temperature increases, and the oil temperature detected by the detecting means Normality determining means for determining that the variable valve timing mechanism is normal when the temperature is lower than a predetermined temperature and the response speed calculated by the first calculation means is higher than the predetermined response speed. .

  In the abnormality detection device for a variable valve timing mechanism of the internal combustion engine, when the oil temperature detected by the detection means is lower than a predetermined temperature and the response speed calculated by the first calculation means is higher than a predetermined response speed, It is determined that the oil of the variable valve timing mechanism has deteriorated.

  When the response speed calculated by the first calculation means is lower than a predetermined response speed, it is determined that the variable valve timing mechanism is abnormal.

  Hereinafter, the details of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of an abnormality detection device for a variable valve timing mechanism of an internal combustion engine according to an embodiment of the present invention. An engine 11 shown in FIG. 1 is a DOHC (Double Overhead Camshaft) type four-cylinder engine, and an intake camshaft 13 and an exhaust camshaft that are independent of each other via a timing chain (not shown). 14, and the intake cam shaft 13 drives the intake valve 15 and the exhaust cam shaft 14 opens and closes the exhaust valve 16. The intake camshaft 13 is provided with a hydraulically driven variable valve timing mechanism (VVT) 17 that adjusts the advance amount of the intake camshaft 13 with respect to the crankshaft 12. In the present embodiment, an example in which the VVT 17 is provided on the intake camshaft 13 is shown, but the present invention can also be applied to an embodiment in which a similar VVT is provided on the exhaust camshaft 14 instead of or in addition to this.

  The VVT 17 uses the lubricating oil of the engine 11 as hydraulic oil. The oil pump 18 is driven in conjunction with the engine 11, and the lubricating oil is pumped up by the oil pump 18 from the oil pan 19 connected to the lower part of the cylinder block 11 a of the engine 11 and storing the lubricating oil. The oil pressure is supplied to the VVT 17 and the oil pressure is controlled by an oil control valve (OCV) 21 provided in the middle of the oil passage 20, whereby the advance amount of the intake camshaft 13 is controlled according to the oil pressure. The oil pan 19 is provided with an oil temperature sensor 22 that detects the temperature of lubricating oil (hereinafter referred to as hydraulic oil). The oil temperature sensor 22 may be disposed in the oil passage 20 or the VVT 17. The oil pan 19 also serves to cool the lubricating oil by dissipating heat to the outside air.

  A camshaft sensor 23 is installed near the intake camshaft 13, and a crankshaft sensor 24 is installed near the crankshaft 12. The crankshaft sensor 24 generates N crankshaft phase detection pulse signals per revolution of the crankshaft 12, whereas the camshaft sensor 23 detects 2N camshaft phase detections per revolution of the intake camshaft 13. Generate a pulse signal. When the maximum advance angle of the intake camshaft 13 is θmax ° CA, the crankshaft phase detection pulse signal number N is set so that N <360 / θmax. Thus, the intake valve is determined by the relative rotation angle between the crankshaft phase detection pulse signal from the crankshaft sensor 24 and the camshaft phase detection pulse signal from the camshaft sensor 23 of the intake camshaft 13 that is generated subsequently. 15 actual valve timing (actual advance angle of intake camshaft 13) is calculated.

  A water temperature sensor 25 for detecting the temperature of cooling water flowing in the water jacket 11b (hereinafter referred to as water temperature) is attached to the cylinder block 11a of the engine 11, and a spark plug 26 is attached to each cylinder head 11c for each cylinder. It has been.

  On the other hand, an air cleaner 28 is provided at the most upstream portion of the intake pipe 27, and an intake air temperature sensor 29 for detecting the intake air temperature is provided downstream thereof. A throttle valve 30 is provided downstream of the intake air temperature sensor 29, and the opening degree of the throttle valve 30 is detected by the throttle sensor 31. An intake pressure sensor 32 that detects the pressure in the intake pipe is provided downstream of the throttle valve 30. Further, a fuel injection valve 34 is attached in the vicinity of the intake port 33 of each cylinder. Further, a vehicle speed sensor 35 is disposed in a vehicle on which the engine 11 is mounted. Further, a hydraulic pressure sensor 36 that detects the hydraulic pressure of the hydraulic oil flowing into the VVT 17 is disposed in the vicinity of the VVT 17 in the oil passage 20. The various sensors described above and a position sensor (206 in FIG. 2) described later are connected to an input port of an engine control unit (ECU) 40, while the OCV 21, spark plug 26, fuel injection valve 34, and the like are connected to the ECU 40. Connected to the output port.

  Next, the engine control unit (ECU) 40 equipped in the abnormality detection device for the variable valve timing mechanism of the internal combustion engine according to the embodiment shown in FIG. 1 will be described. The ECU 40 comprises a general digital computer, and is connected to a CPU, a RAM, a ROM, an input port and an output port, and an AD converter and an output port connected to the input port via a bidirectional bus (not shown). And a driving circuit connected to. Analog voltage output from the above-described various sensors installed in each part of the vehicle on which the ECU 40 is mounted is input to the input port via an AD converter, or digital signals from the various sensors are directly input. In response to a control signal from the output port to the drive circuit by the ECU 40, electric power is supplied from an unillustrated battery or alternator to electrical loads such as the OCV 21, spark plug 26, fuel injection valve 34, and the like.

  FIG. 2 is an operation explanatory view of the valve mechanism of the variable valve timing mechanism shown in FIG. A valve operating mechanism 200 shown in the upper part of FIG. 2 is a mechanism of the VVT 17 for changing the valve timing of the intake valve 15 of the VVT 17 by an oil control valve (OCV) 21 shown in the lower part, and operates as follows.

  The valve operating mechanism 200 has a cam 201 for opening and closing the intake valve 15 provided for one cylinder. When the relative position of the cam 201 to the intake valve 15 in the rotation axis direction of the cam 201 (hereinafter referred to as the relative position of the cam 201) changes, the cam 201 has an open / close valve characteristic (for example, valve opening timing, The valve opening period, lift amount, etc.) are changed. The cam 201 is fixed to one camshaft 202 so that the rotation axis of the cam 201 is coaxial with the rotation axis of the camshaft 202.

  Since the cam 201 is fixed to the camshaft 202 in this way, when the camshaft 202 moves in the axial direction, the cam 201 also moves in the rotational axis direction, thereby changing the relative position of the cam 201 and the intake valve 15. The on-off valve characteristics are changed. Therefore, the on-off valve characteristics of the intake valve 15 can be changed by moving the camshaft 201 in the axial direction. The on / off valve characteristic of the intake valve 15 can be controlled to the target on / off valve characteristic by moving the cam shaft 202 in the axial direction so that the relative position of the cam 201 becomes the target relative position.

  Also, a hydraulic camshaft drive device 203 for moving the camshaft 202 in the axial direction is provided at one end of the camshaft 202, and this hydraulic camshaft drive device 203 is an open / close valve for the intake valve 15. It functions as a changing means for changing the characteristics. The hydraulic camshaft drive device 203 includes a hydraulic cylinder 204 and an OCV 21. As shown in FIG. 2, the hydraulic cylinder 204 accommodates a piston 205 attached to one end of the camshaft 202, and the camshaft 202 is moved in the axial direction by sliding the piston 205 in the hydraulic cylinder 204. Move to.

  The position of the piston 205 in the hydraulic cylinder 204 is detected by a position sensor 206, and the output of the position sensor 206 is input to an input port via an A / D converter corresponding to the ECU 40. Based on the output of the position sensor 206, the position of the camshaft 202, that is, the relative position of the cam 201 is detected. On the other hand, the operation of the piston 205 in the hydraulic cylinder 204, that is, the movement of the camshaft 202 in the axial direction is based on the on / off duty ratio (the time when the signal is on) of the control pulse signal transmitted to the actuator 207 of the OCV 21. This is controlled by changing the ratio of the signal on time to the sum of the time when the signal is off.

  That is, when the duty ratio of the control pulse signal transmitted to the actuator 207 of the OCV 21 is made larger than the reference duty ratio, the cam shaft 202 moves in one direction in the axial direction, and the relative position of the cam 201 moves in one direction. To do. Thereby, the on-off valve characteristic of the intake valve 15 changes in a certain direction. Note that the fact that the on-off valve characteristics of the intake valve 15 change in a certain direction means, for example, that the valve opening timing becomes earlier, the valve opening period becomes longer, or the lift amount becomes larger.

  Conversely, when the duty ratio of the control pulse signal transmitted to the actuator 207 of the OCV 21 is made smaller than the reference duty ratio, the camshaft 202 moves in the direction opposite to the one direction in the axial direction, and the cam 201 The position moves in the direction opposite to the one direction. As a result, the on-off valve characteristic of the intake valve 15 changes in a direction opposite to the certain direction. Note that the fact that the on-off valve characteristic of the intake valve 15 changes in a direction opposite to the certain direction means that, for example, the valve opening timing is delayed, the valve opening period is shortened, or the lift amount is reduced. To do.

  In addition, the greater the deviation of the duty ratio from the reference duty ratio, the greater the distance that the relative position of the cam 201 moves per unit time, and thus the on-off valve characteristics of the intake valve 15 per unit time. The degree of change will also increase. Here, the reference duty ratio is a duty ratio that does not actuate the piston 205 of the hydraulic cylinder 204, that is, a duty ratio that does not change the relative position of the cam 201 and does not change the on-off valve characteristics of the intake valve 15. is there. This reference duty ratio is a duty ratio determined for each hydraulic camshaft drive device 203 in accordance with the hydraulic pressure of the hydraulic oil and the oil temperature.

  Next, the flow of hydraulic oil supplied from the oil pan 19 to the valve operating mechanism 200 of the VVT 17 via the OCV 21 and returning to the oil pan 19 via the OCV 21 will be described below. When it is desired to advance the valve timing of the intake valve 15, the piston 205 of the valve mechanism 200 is moved in the first direction 211 by the OCV 21, and the hydraulic oil pumped from the oil passage 20 is moved via the OCV 21 and the oil passage 212. The hydraulic oil in the second hydraulic chamber (extrusion hydraulic chamber) 214 of the hydraulic cylinder 204 is sent to the first hydraulic chamber (extrusion hydraulic chamber) 213 of the two hydraulic chambers of the hydraulic cylinder 204 provided in the valve mechanism 200. The oil is returned to the oil pan 19 via the oil passage 215, the OCV 21 and the oil passage 216.

  On the other hand, when the valve timing of the intake valve 15 is to be delayed, the OCV 21 causes the piston 205 of the valve mechanism 200 to move in the second direction 217 opposite to the first direction 211, and the hydraulic oil fed from the oil passage 20 is pumped. The oil is sent to the second hydraulic chamber 214 of the hydraulic cylinder 204 of the VVT 17 via the OCV 21 and the oil passage 215, and the hydraulic oil in the first hydraulic chamber 213 of the hydraulic cylinder 204 is oiled via the oil passage 212, the OCV 21 and the oil passage 218. Return to pan 19. When it is desired to fix the valve timing of the intake valve 15 at the current position, the valve mechanism 200 is operated by the OCV 21 so that the spools 221a, 221b, 221c in the cylinder 220 of the OCV 21 are in the neutral position in the cylinder 220. It moves and the ports 222a and 222b of the cylinders 220 of the oil passages 215 and 212 between the OCV 21 and the valve mechanism 200 are closed by the spools 221a and 221b. A similar valve operating mechanism is also provided in other embodiments in which the exhaust camshaft 14 is provided with a similar VVT.

  The abnormality detection device for VVT according to the present invention has a difference between a target valve operating characteristic value determined in accordance with the operating state of the engine and an actual valve operating characteristic value measured during operation by a deviation of a predetermined value or more. Is provided with a determination means (execution of the following processing by the ECU 40) for determining that it is abnormal and an actuator for changing the valve operating characteristic of the VVT 17, that is, the valve mechanism 200 shown in FIG. Here, in this embodiment, the valve operating characteristic means valve timing. The control of the engine control unit ECU 40 will now be described in detail. The routine described below is executed every predetermined cycle, for example, every 0.1 second.

FIG. 3 is a flowchart of the first control routine of the VVT abnormality detection apparatus according to the present invention.
First, in step S1, a signal detected by the crankshaft sensor 24 is read to calculate the engine speed NE.

  In step S2, the intake pipe pressure PM detected by the intake pressure sensor 32, the oil temperature OT detected by the oil temperature sensor 22, and the hydraulic pressure OP detected by the hydraulic sensor 36 are read. The oil temperature OT is detected by the water temperature detected by the water temperature sensor 25, the engine speed NE, the intake air temperature detected by the intake air temperature sensor 29, and an air flow meter (not shown) instead of being detected by the oil temperature sensor 22. An estimated oil temperature estimated based on the detected intake air amount to the engine cylinder or the fuel injection amount calculated by the fuel injection control by the ECU 40 may be used.

  In step S3, an intake valve 15 corresponding to the current operating state of the engine is referred to with reference to a map (not shown) based on the engine speed NE calculated in step S1 and the intake pipe pressure (load) PM detected in step S2. Target valve timing (target advance amount of intake camshaft 202) is calculated.

  In step S4, the crankshaft phase detection pulse signal from the crankshaft sensor 24 and the camshaft phase detection pulse signal from the camshaft sensor 23 of the intake camshaft 13 are read.

  In step S5, the actual valve timing of the intake valve 15 (actual advance angle amount of the intake camshaft 13) is calculated from the relative rotation angle between the crankshaft phase detection pulse signal and the camshaft phase detection pulse signal read in step S4. To do.

  In step S6, duty control of the actuator 207 of the OCV 21 is performed so that the actual valve timing of the intake valve 15 calculated in step S5 becomes the target valve timing calculated in step S3, and the valve timing of the intake valve 15 is adjusted. Here, the map for calculating the oil flow rate will be described below.

  FIG. 4 is a diagram showing a map for calculating the oil flow rate from the oil temperature and the hydraulic pressure, (A) is a diagram showing a map created by experimentally determining the relationship between the oil temperature and the hydraulic pressure, and (B). It is a figure which shows the map created by calculating | requiring theoretically the relationship between oil temperature and an oil flow, (C) is a figure which shows the map of the relationship between a hydraulic pressure and an oil flow. These maps are stored in the RAM of the ECU 40. As shown in FIG. 4 (A), when the oil temperature increases, the hydraulic pressure decreases, and the operation responsiveness for driving the VVT actuator decreases, and normal control of the VVT is no longer possible. To do. The map shown in FIG. 4B calculates the oil flow rate from the oil temperature OT and the hydraulic pressure OP read in step S2 using Bernoulli's theorem, and shows the relationship between the oil temperature and the oil flow rate from the calculation result. FIG. According to Bernoulli's theorem, an equation representing an energy conservation law for a fluid flow is given by the following equation for an ideal fluid.

^{v 2/2 + p / ρ} + gz = c ( constant) ... (1)
Here, v is the speed (flow rate) of the hydraulic oil, p is the hydraulic pressure, ρ is the density (viscosity) of the fluid (hydraulic oil), g is the acceleration of gravity, z is the height from the reference plane, and c is a constant. Since ρ, that is, the density of hydraulic oil can be obtained from the oil temperature, the oil flow rate can be obtained from the above equation (1) if the oil pressure is known. Alternatively, a map shown in FIG. 4C showing the oil pump characteristics is stored in the ECU 40, and the oil flow rate is calculated from the read hydraulic pressure.

  In step S7, the oil pressure OP corresponding to the oil temperature OT read in step S2 is calculated with reference to the map shown in FIG. 4A, and compared with the oil pressure OP and a predetermined value. In order to execute the VVT abnormality determination, the process proceeds to step S8, and when the hydraulic pressure ≦ the predetermined value, the process ends.

  In step S8, the oil flow rate is calculated from the oil temperature OT read in step S2 with reference to the map shown in FIG.

  In step S9, the oil flow rate calculated in step S8 is compared with a predetermined value. If the oil flow rate is greater than the predetermined value, it is determined that VVT is normal, and the process proceeds to step S10. If the oil flow rate ≦ the predetermined value, VVT abnormality determination processing is performed. This routine is terminated without executing.

  In step S10, the following expression (2) is calculated.

VVT deviation =
VVT target valve timing-VVT actual valve timing (2)
In step S11, the VVT deviation calculated in step S10 is compared with the deviation determination value (fixed value). When VVT deviation> deviation determination value, it is determined that the VVT abnormality determination condition is satisfied, and the process proceeds to step S12, where VVT deviation ≦ When it is a deviation determination value, the routine is terminated without executing the VVT abnormality determination process.

  In step S12, it is determined whether or not a predetermined time (t seconds) has elapsed since it was determined that VVT deviation> deviation determination value in step S11. If elapsed time ≧ t, the process proceeds to step S13. When <t, this routine is terminated.

  In step S13, a VVT abnormality determination flag is set and displayed on the display panel mounted on the vehicle to notify the driver of the VVT abnormality.

  As described above, the determination means executed in the first control routine of the present invention is the calculation means (step S8) for calculating the flow rate of the hydraulic oil that drives the valve mechanism 200, and the hydraulic oil calculated by the calculation means. When the flow rate is less than the predetermined value, or when the VVT deviation does not exceed the deviation determination value even when the hydraulic oil flow rate is equal to or higher than the predetermined value, or when the time exceeds the predetermined time (t seconds), the determination means (step S9). ˜S13) is interrupted (step S9), and as described above, these means are achieved by executing each step.

  Further, according to the first control, when the oil temperature is high and the hydraulic pressure is low, the VVT abnormality determination is not performed by step S7, and when the oil temperature is low and the hydraulic pressure is high, the VVT abnormality determination is not performed by step S9. it can.

  FIG. 5 is a flowchart of a second control routine of the VVT abnormality detection apparatus according to the present invention. Since steps S1 to S6 and steps S10 to S13 in the second control routine of the present invention perform the same processing as the same step numbers in the first control routine, description thereof will be omitted. Steps S7 to S9 will be described below with reference to FIGS.

  6 is a diagram showing a map for calculating the oil viscosity from the oil temperature, FIG. 7 is a diagram showing a map for calculating the reference VVT response speed (determination time) from the oil viscosity, and FIG. 8 is a diagram showing the reference VVT from the oil temperature. It is a figure which shows the map which calculates response speed (judgment time). These maps are stored in the RAM of the ECU 40.

  The map shown in FIG. 6 is created using the following equation (3) of Walther-ASTM that gives the relationship between oil temperature and oil viscosity.

loglog (ν + a) = A−BlogT (3)
Here, ν is the kinematic viscosity expressed in cSt (centistokes) of the CGS unit system, a, A and are constants determined by the type of oil (k is the Boltzmouth constant), and T is the absolute temperature. As can be seen from equation (3), the kinematic viscosity ν decreases as the temperature increases.

  The map shown in FIG. 7 is created from the experimental results as follows. That is, with the engine speed NE kept constant, the oil temperature of the hydraulic oil is changed to change the viscosity, and the valve mechanism 200 is driven with the hydraulic oil having the changed viscosity for a predetermined time (for example, 1 second). Measure the valve timing change (° CA), and calculate the reference VVT response speed (° CA / sec) from the valve timing change per predetermined time. From the calculation results, oil viscosity and VVT response speed Create a map showing the relationship. On the other hand, a map indicating the relationship between the oil viscosity and the determination time t is created from the reference VVT response speed and the deviation determination value (fixed value) calculated as described above using the following equation (4).

Determination time t = deviation determination value / reference VVT response speed (4)
The map shown in FIG. 8 calculates the oil temperature from the oil viscosity with reference to the map of FIG. 6, and obtains the relationship between the oil temperature and the reference VVT response speed and the relationship between the oil temperature and the determination time with reference to FIG. create.

  In step S7, the oil viscosity corresponding to the oil temperature OT read in step S2 is calculated with reference to the map shown in FIG.

  In step S8, a reference VVT response speed corresponding to the oil viscosity calculated in step S7 is calculated with reference to the map shown in FIG.

  In step S9, the determination time t corresponding to the oil temperature OT read in step S2 is calculated using equation (4) with reference to the map shown in FIG.

  As described above, the determination means executed in the second control routine of the present invention is calculated by the first calculation means (step S7) for calculating the viscosity of the hydraulic oil that drives the valve mechanism 200 and the first calculation means. The second calculating means (step S8) for calculating the VVT reference response speed with respect to the determined viscosity, and an abnormality for determining that the VVT is abnormal when the duration time during which the deviation is larger than the reference response speed has passed a predetermined time t. Determination means (steps S10 to 13), and as described above, these means are achieved by executing each step.

  In addition, according to the second control, when the hydraulic oil temperature is high, the VVT abnormality determination can be made without being based on the hydraulic pressure, and therefore an erroneous determination of the VVT abnormality can be prevented.

  FIG. 9 is a flowchart of the third control routine of the VVT abnormality detection apparatus according to the present invention. FIG. 10 is a diagram showing an example in which steps S2 and S3 in the flowchart shown in FIG. 9 are replaced with other processes. (A) is a diagram showing the relationship between the oil temperature and the VVT response speed in the normal state of VVT, the oil deterioration state, and the abnormal state of VVT, and (B) in FIG. 11 shows the normal state of VVT, the oil deterioration state, and It is a figure which shows the table of the result of the temporary determination with respect to the abnormal state of VVT abnormality, and this determination.

  First, in step S1, the oil temperature is read from the oil temperature sensor 22. Note that the oil temperature OT may be an estimated value as previously described in step S2 of the first control routine.

  In step S2, the oil viscosity corresponding to the oil temperature OT read in step S1 is calculated with reference to the map shown in FIG.

  In step S3, the VVT response speed corresponding to the oil viscosity calculated in step S2 is calculated with reference to the map shown in FIG.

  Or you may perform the process described below shown in FIG. 10 instead of step S2 and S3.

  In step S101, a VVT deviation is calculated. In step S102, it is determined whether the VVT deviation is larger than a predetermined value. If VVT deviation> predetermined value, the process proceeds to step S103, and the VVT deviation is stored for the first time, and then in step S104. The time (t) during which the condition is satisfied is counted. When VVT deviation ≦ predetermined value in step S102, the process proceeds to step S105, and a value obtained by dividing the difference between the deviation stored value (VT) and the predetermined value by the time (t) is set as the VVT response speed.

  In step S4, in order to determine whether the oil temperature OT is in the first range (temperature higher than T1 and lower than T2 (> T1): provisional determination section), when T1 <OT, the process proceeds to step S5. When OT ≦ T1, this routine is terminated.

  In step S5, in order to determine whether or not the oil temperature OT is in the second range (temperature higher than T2: main determination section), when OT <T2, the current oil temperature is considered to be in the temporary determination section. Proceeding to step S6, when OT ≧ T2, the current oil temperature is regarded as being in the present determination section, and the process proceeds to step S7.

  In step S6, it is determined whether or not the VVT response speed calculated in step S3 is lower than the abnormality determination value. If VVT response speed <abnormal determination value, the process proceeds to step S8. If VVT response speed ≧ abnormal determination value, This routine ends.

  In step S7, as in step S6, it is determined whether or not the VVT response speed calculated in step S3 is lower than the abnormality determination value. If VVT response speed <abnormal determination value, the process proceeds to step S9, and VVT response speed ≧ abnormal If it is a determination value, the process proceeds to step S10.

  In step S8, a temporary determination flag is set.

  In step S9, a VVT abnormality determination flag is set and displayed on a display panel mounted on the vehicle to notify the driver of the VVT abnormality and prompt the parts to be inspected.

  In step S10, it is determined whether or not a temporary determination flag is set. If the temporary determination flag = 1 (ON), the process proceeds to step S11. If the temporary determination flag = 0 (OFF), the process proceeds to step S12.

  In step S11, the display is displayed on a display panel mounted on the vehicle, and the driver is prompted to replace the operating oil because the operating oil (oil) has deteriorated.

  In step S12, it is determined that VVT is normal, and the VVT abnormality determination flag is set to zero.

  As described above, the determination means executed in the third control routine of the present invention calculates the first response speed of the VVT 17 when the temperature of the hydraulic oil that drives the valve mechanism 200 is in the first range. 1 calculation means (steps S2, S3), and first determination means (steps S4 to S6, S8) for setting a first abnormality determination flag when the first response speed calculated by the first calculation means is smaller than the abnormality determination value; The second calculation means (steps S2 and S3) for calculating the second response speed of the VVT 17 when the oil temperature of the hydraulic oil for driving the valve mechanism 200 is in the second range higher than the first, and the second calculation means The second determination means (steps S4, S5, S7, S9) for setting a second abnormality determination flag when the second response speed calculated by the step is smaller than the abnormality determination value, and the first abnormality determination flag and the second abnormality determination flag are Do not stand together When, VVT17 normality determination means is determined to be normal (step S4 to S8, S10, S12) and, provided with, as described above, these means are achieved by the execution of each step.

  Further, according to the third control, when the hydraulic oil temperature is high, the VVT abnormality determination can be made without being based on the hydraulic pressure, so that the erroneous determination of the VVT abnormality can be prevented.

  FIG. 12 is a flowchart of the fourth control routine of the VVT abnormality detection device according to the present invention, and FIG. 13 is a diagram showing the oil temperature at which the change in the reference VVT response speed in the normal state, oil deterioration state, and abnormal state of VVT becomes constant. It is.

  First, in step S1, it is determined whether or not this routine is the first time. When the determination result is YES, the process proceeds to step S2, and when the determination result is NO, the process proceeds to step S3.

  In step S2, the previous VVT response speed (hereinafter referred to as the previous VVT speed) is initialized to 0 ° CA / sec, and the oil temperature at the time of determining the previous VVT speed (hereinafter referred to as the previous oil temperature) is initialized to 0 ° C. .

  In step S3, the oil temperature is read from the oil temperature sensor 22. Note that the oil temperature OT may be an estimated value as previously described in step S2 of the first control routine.

  In step S4, oil temperature difference = previous oil temperature−current oil temperature is calculated. The current oil temperature means the oil temperature at the time of the current VVT response speed determination, and is the oil temperature read in step S3.

  In step S5, it is determined whether or not the oil temperature difference calculated in step S4 is a predetermined temperature, for example, 5 ° C. or more. When the oil temperature difference ≧ the predetermined temperature, the process proceeds to step S6, and when the oil temperature difference <the predetermined temperature, this routine is executed. finish.

  In step S6, the oil viscosity corresponding to the oil temperature read in step S3 is calculated with reference to the map shown in FIG.

  In step S7, the current VVT speed corresponding to the oil viscosity calculated in step S6 is calculated with reference to the map shown in FIG.

  Or you may perform the process mentioned above shown in FIG. 10 instead of step S6 and S7.

  In step S8, VVT speed difference = previous VVT speed−current VVT speed is calculated.

  In step S9, it is determined whether or not the VVT speed difference calculated in step S8 is smaller than a determination value. If VVT speed difference <determination value, the process proceeds to step S10. If VVT speed difference ≧ determination value, this routine is executed. finish. The determination in step S9 is an increase in the response speed of the VVT 17 calculated in steps S6 and S7 with respect to the oil temperature increment (ΔOT) of the hydraulic oil that drives the valve mechanism 200, here the predetermined temperature (5 ° C.). (ΔRV) is performed in order to obtain an oil temperature at which the VVT speed becomes constant as the inclination approaches zero and the inclination becomes zero. Here, the increment of the response speed with respect to the predetermined temperature is the change rate (ΔRV / ΔOT) of the VVT speed difference calculated in step S8. As shown in FIG. 13, in the VVT normal state line 1301, the oil deterioration state line 1302, and the VVT abnormal state line 1303, the oil temperature at which the VVT speed becomes constant is around 1311 in the VVT normal state line 1301, and the oil deterioration state Line 1302 is near 1312.

  In step S10, it is determined whether or not the VVT speed is smaller than the abnormality determination value. If VVT speed <abnormal determination value, the VVT response is poor and the process proceeds to step S11, where VVT speed ≧ abnormal determination value. If the VVT response is within the allowable range, the VVT is regarded as normal and the process proceeds to step S12.

  In step S11, a VVT abnormality determination flag is set and displayed on a display panel mounted on the vehicle to notify the driver of the VVT abnormality and prompt inspection of parts.

  In step S12, it is determined whether or not the oil temperature is higher than the determination temperature. If the oil temperature is greater than the determination temperature, it is determined that the oil has deteriorated, and the process proceeds to step S13. Proceed to step S14.

  In step S13, the information is displayed on a display panel mounted on the vehicle to inform the driver that the hydraulic oil (oil) has deteriorated and that the hydraulic oil is about to be replaced.

  In step S14, it is determined that VVT is normal, and the VVT abnormality determination flag is set to zero.

  As described above, the determination means executed in the fourth control routine of the present invention is the first calculation means (steps S6 and S7) for calculating the response speed of the VVT 17, and the oil temperature of the hydraulic oil that drives the valve mechanism 200. Second calculation means (step S8) for calculating the change rate (ΔRV / ΔOT) of the response speed increment (ΔRV) of the VVT 17 calculated by the first calculation means with respect to the increment (ΔOT), and the change rate (ΔRV / ΔOT) ) Detects the oil temperature when the oil temperature decreases as the oil temperature increases (step S9), and the response speed calculated by the first calculation means when the oil temperature detected by the detection means is lower than the predetermined temperature Normality determination means (steps S10, S12, S14) for determining that the VVT 17 is normal when the response speed is higher than the predetermined response speed. Tsu is achieved by the execution of flops.

  Further, according to the fourth control, when the hydraulic oil temperature is high, the VVT abnormality determination can be made without being based on the hydraulic pressure, so that erroneous determination of the VVT abnormality can be prevented.

  FIG. 14 is a flowchart of a fifth control routine of the VVT abnormality detection apparatus according to the present invention, and FIG. 15 is a diagram showing a normal distribution of VVT deviations.

  First, in step S1, a signal detected by the crankshaft sensor 24 is read to calculate the engine speed NE.

  In step S2, the intake pipe pressure PM detected by the intake pressure sensor 32, the oil temperature OT detected by the oil temperature sensor 22, and the hydraulic pressure OP detected by the hydraulic sensor 36 are read. Note that the oil temperature OT may be an estimated value as previously described in step S2 of the first control routine.

  In step S3, an intake valve 15 corresponding to the current operating state of the engine is referred to with reference to a map (not shown) based on the engine speed NE calculated in step S1 and the intake pipe pressure (load) PM detected in step S2. Target valve timing (target advance amount of intake camshaft 202) is calculated.

  In step S4, the crankshaft phase detection pulse signal from the crankshaft sensor 24 and the camshaft phase detection pulse signal from the camshaft sensor 23 of the intake camshaft 13 are read.

  In step S5, the actual valve timing of the intake valve 15 (actual advance angle amount of the intake camshaft 13) is calculated from the relative rotation angle between the crankshaft phase detection pulse signal and the camshaft phase detection pulse signal read in step S4. To do.

  In step S6, duty control of the actuator 207 of the OCV 21 is performed so that the actual valve timing of the intake valve 15 calculated in step S5 becomes the target valve timing calculated in step S3, and the valve timing of the intake valve 15 is adjusted.

  In step S7, the following equation (2) is calculated.

VVT deviation =
VVT target valve timing-VVT actual valve timing (2)
In step S8, in order to determine whether or not the oil temperature OT is within the first range (temperature higher than T1 and lower than T2 (> T1): provisional determination section) from the oil temperature read in step S2, T1 <OT If YES, the process proceeds to step S9. If OT≤T1, this routine is terminated.

  In step S9, in order to determine whether or not the oil temperature OT is in the second range (temperature higher than T2: main determination section), when OT <T2, the current oil temperature is considered to be in the temporary determination section. Proceeding to step S10, when OT ≧ T2, the current oil temperature is regarded as being in the present determination section, and the process proceeds to step S11.

In step S10, the first standard deviation σ ₁ in the oil temperature tentative determination section is obtained from the VVT deviation calculated in step S7.

In step S11, the second standard deviation σ ₂ in the oil temperature main determination section is obtained from the VVT deviation calculated in step S7.

Here, a method for obtaining the standard deviation σ (first standard deviation σ ₁ , second standard deviation σ ₂ ) from the VVT deviation will be briefly described. First, normal distributions 1501 and 1502 of VVT deviations as shown in FIG. 15 are created based on the VVT deviations calculated in step S7. In order to create these normal distributions, it is necessary to sample a lot of VVT deviation data, and therefore, it takes about several tens of minutes after engine operation. Identify whether the sampled VVT deviation is in the range of 0-5 ° CA, 5-10 ° CA,..., And divide the frequency (number of appearances) of the VVT deviation identified in each range by the total number of samplings Thus, the frequency (number of appearances / total number of samplings) is obtained, and a normal distribution is created with the deviation (° CA) on the horizontal axis and the frequency of deviation on the vertical axis, as shown in FIG. The standard deviation σ is obtained from the normal distribution thus created using a general statistical method.

In step S12, it is determined whether or not the value obtained by multiplying the first standard deviation σ ₁ calculated in step S10 by the coefficient k1 is lower than the abnormality determination value. If the first standard deviation σ ₁ * k1> the abnormality determination value, Proceeding to step S13, if the first standard deviation σ ₁ * k1 ≦ abnormality judgment value, this routine is terminated. Here, k1 is a coefficient set to determine an allowable value of deviation from the first standard deviation.

  In step S13, a temporary determination flag is set.

In step S14, similarly to step S12, it is determined whether or not the value obtained by multiplying the second standard deviation σ ₂ calculated in step S11 by the coefficient k2 is lower than the abnormality determination value, and the second standard deviation σ ₂ * k2> abnormal. If it is a determination value, the process proceeds to step S15. If the second standard deviation σ ₂ * k2 ≦ the abnormality determination value, the process proceeds to step S16. Here, k2 is a coefficient set to determine an allowable value of deviation from the second standard deviation.

  In step S15, a VVT abnormality determination flag is set and displayed on a display panel mounted on the vehicle to notify the driver of the VVT abnormality and prompt the operator to replace the hydraulic oil.

  In step S16, it is determined whether or not a temporary determination flag is set. When the temporary determination flag = 1 (ON), the process proceeds to step S17, and when the temporary determination flag = 0 (OFF), the process proceeds to step S18.

  In step S17, the information is displayed on a display panel mounted on the vehicle to inform the driver that the hydraulic oil (oil) has deteriorated and that the hydraulic oil is about to be replaced.

  In step S18, it is determined that the VVT is normal, and the VVT abnormality determination flag is set to zero.

  As described above, the determination means executed in the fifth control routine of the present invention is the first calculation means (steps S10 and S11) for calculating the normal distribution from the variation in deviation between the target valve operating characteristic value and the actual valve operating characteristic value. ), Second calculation means (steps S10 and S11) for calculating the standard deviation value of the deviation from the normal distribution, and the oil temperature of the hydraulic oil driving the valve mechanism 200 is higher than a predetermined temperature, and the standard deviation value is predetermined. The abnormality determining means (step S14) for determining that the VVT 17 is abnormal when exceeding the above range, as described above, these means are achieved by executing each step.

  Further, according to the fifth control, when the oil temperature of the hydraulic oil is high, the VVT abnormality determination can be made without being based on the hydraulic pressure, so that the erroneous determination of the VVT abnormality can be prevented.

  As described above, according to the abnormality detection device for the variable valve timing mechanism of the internal combustion engine according to the first invention, when the hydraulic oil temperature is high and the hydraulic pressure is low and the VVT response is poor, or the hydraulic temperature is low and the hydraulic pressure is low. Therefore, it is possible to provide an abnormality detection device for a variable valve timing mechanism of an internal combustion engine that makes a determination of VVT abnormality without error when VVT is high and VVT response is poor.

  Further, according to the abnormality detection device for the variable valve timing mechanism of the internal combustion engine according to the second invention, when the oil temperature of the hydraulic oil is high and the response of VVT is poor, the abnormality is determined based on the oil pressure without making a mistake in the VVT. An abnormality detection device for a variable valve timing mechanism of an internal combustion engine can be provided.

It is a schematic block diagram of the abnormality detection apparatus of the variable valve timing mechanism of the internal combustion engine which concerns on one Embodiment of this invention. It is operation | movement explanatory drawing of the valve mechanism of the variable valve timing mechanism shown in FIG. It is a flowchart of the 1st control routine of the VVT abnormality detection apparatus by this invention. It is a figure which shows the map which calculates oil flow volume from oil temperature and oil_pressure | hydraulic, (A) is a figure which shows the map created by calculating | requiring experimentally the relationship between oil temperature and oil_pressure | hydraulic, (B) It is a figure which shows the map created by calculating | requiring theoretically the relationship with an oil flow, (C) is a figure which shows the map of the relationship between a hydraulic pressure and an oil flow. It is a flowchart of the 2nd control routine of the VVT abnormality detection apparatus by this invention. It is a figure which shows the map which calculates oil viscosity from oil temperature. It is a figure which shows the map which calculates a reference | standard VVT response speed and determination time from oil viscosity. It is a figure which shows the map which calculates a reference | standard VVT response speed and determination time from oil temperature. It is a flowchart of the 3rd control routine of the VVT abnormality detection apparatus by this invention. It is a figure which shows the example which replaced step S2 and S3 of the flowchart shown in FIG. 9 with another process. (A) is a figure which shows each relationship between the oil temperature in the normal state of VVT, an oil deterioration state, and the abnormal state of VVT, and a reference | standard VVT response speed, (B) is a normal state of VVT, an oil deterioration state, and abnormality of VVT. It is a figure which shows the table of the result of the temporary determination with respect to a state, and this determination. It is a flowchart of the 4th control routine of the VVT abnormality detection apparatus by this invention. It is a figure which shows the oil temperature from which the change of the reference | standard VVT response speed in the normal state of VVT, an oil deterioration state, and an abnormal state becomes constant. It is a flowchart of the 5th control routine of the VVT abnormality detection apparatus by this invention. It is a figure which shows the normal distribution of VVT deviation.

Explanation of symbols

11 Engine 12 Crankshaft 13 Intake camshaft 14 Exhaust camshaft 15 Intake valve 16 Exhaust valve 17 Variable valve timing mechanism (VVT)
18 Oil pump 21 Oil control valve (OCV)
22 Oil temperature sensor 23 Cam shaft sensor 24 Crank shaft sensor 25 Water temperature sensor 29 Intake temperature sensor 32 Intake pressure sensor 36 Hydraulic sensor 40 Engine control unit (ECU)

Claims (6)

Determining means for determining abnormality of a variable valve timing mechanism that changes valve operating characteristics including at least one of valve timing, valve lift amount, and valve opening period of one or both of an intake valve and an exhaust valve of an internal combustion engine; In an abnormality detection device for a variable valve timing mechanism of an internal combustion engine comprising: an actuator for changing the valve operating characteristic of a variable valve timing mechanism;
The determination means is
First calculating means for calculating a first response speed of the variable valve timing mechanism when an oil temperature of the hydraulic oil for driving the actuator is in a first range;
First determination means for setting a first abnormality determination flag when the first response speed calculated by the first calculation means is smaller than an abnormality determination value;
Second calculating means for calculating a second response speed of the variable valve timing mechanism when the temperature of the hydraulic oil for driving the actuator is in a second range higher than the first;
Second determination means for setting a second abnormality determination flag when the second response speed calculated by the second calculation means is smaller than an abnormality determination value;
Normal determination means for determining that the variable valve timing mechanism is normal when the first abnormality determination flag and the second abnormality determination flag are not standing together;
An abnormality detection device for a variable valve timing mechanism of an internal combustion engine, comprising: The normality determining means determines that the oil of the variable valve timing mechanism is deteriorated when only the first abnormality determination flag is set and the second abnormality determination flag is not set.
The abnormality detection device for a variable valve timing mechanism of an internal combustion engine according to claim 1. The normality determining means determines that the variable valve timing mechanism is abnormal when the first abnormality determination flag and the second abnormality determination flag stand together.
The abnormality detection device for a variable valve timing mechanism of an internal combustion engine according to claim 1. Determining means for determining abnormality of a variable valve timing mechanism that changes valve operating characteristics including at least one of valve timing, valve lift amount, and valve opening period of one or both of an intake valve and an exhaust valve of an internal combustion engine; An abnormality detecting device for a variable valve timing mechanism of an internal combustion engine comprising: an actuator that changes the valve operating characteristic of the variable valve timing mechanism;
The determination means is
First calculating means for calculating a response speed of the variable valve timing mechanism;
A change rate (ΔRV / ΔOT) of an increase (ΔRV) of the response speed of the variable valve timing mechanism calculated by the first calculation means with respect to an increase (ΔOT) of the oil temperature of the hydraulic oil that drives the actuator is calculated. 2 calculating means;
Detecting means for detecting an oil temperature when the rate of change (ΔRV / ΔOT) decreases with an increase in the oil temperature;
Normal determination means for determining that the variable valve timing mechanism is normal when the oil temperature detected by the detection means is lower than a predetermined temperature and the response speed calculated by the first calculation means is higher than a predetermined response speed. When,
An abnormality detection device for a variable valve timing mechanism of an internal combustion engine, comprising: When the oil temperature detected by the detection means is lower than a predetermined temperature and the response speed calculated by the first calculation means is higher than a predetermined response speed, it is determined that the oil of the variable valve timing mechanism has deteriorated. ,
The abnormality detection device for a variable valve timing mechanism of an internal combustion engine according to claim 4. When the response speed calculated by the first calculation means is lower than a predetermined response speed, the variable valve timing mechanism is determined to be abnormal.
The abnormality detection device for a variable valve timing mechanism of an internal combustion engine according to claim 4.

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