JP2010203390A - Control device for variable valve train - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a variable valve train capable of suitably controlling the operation of a variable valve train even if a sensor having a relatively narrow detectable pressure range is used. <P>SOLUTION: The control device 1 for a variable valve train includes steps of: calculating an upper limit rotation speed NECVTH and a lower rotation limit speed NECVTL based on an engine water temperature TW (steps 1-2 in Fig.5(not shown)); permitting the operation of a cam phase variable mechanism 10 when an engine speed NE>NECVTH is satisfied (steps 11-13 in Fig.6); prohibiting the operation of the cam phase variable mechanism 10 when NE≤NECVTL is satisfied (steps 14, 18 in Fig.6); and permitting the operation of the cam phase variable mechanism 10 when NECVTL<NE≤NECVTH is satisfied and hydraulic oil pressure POIL detected by a hydraulic sensor 23 reaches operation limit hydraulic pressure POILLIM or higher (steps 14, 16, 13 in Fig.6). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for a variable valve mechanism that controls the operation of a variable valve mechanism that can change the opening and closing timing of an intake valve and / or an exhaust valve of an internal combustion engine.

  As a conventional variable valve mechanism control device, for example, one disclosed in Patent Document 1 is known. This variable valve mechanism is provided with an intake cam phase variable mechanism that is driven by the hydraulic pressure of hydraulic oil pressurized by a hydraulic pump driven by an internal combustion engine and can change the opening / closing timing of the intake valve. In this variable valve mechanism control device, the hydraulic pressure of the hydraulic oil is detected by a hydraulic pressure sensor, and when the detected hydraulic pressure is less than a predetermined value, sufficient hydraulic pressure to drive the variable valve mechanism is not secured. While the operation of the variable valve mechanism is prohibited, the operation of the variable valve mechanism is permitted when the hydraulic pressure is equal to or greater than the predetermined value.

Japanese Patent Laid-Open No. 2004-301101

  However, in this conventional control device for a variable valve mechanism, the hydraulic pressure of the hydraulic oil that changes in accordance with the operating state of the internal combustion engine must be detected over the entire area, so a hydraulic sensor with a wide detectable pressure range is provided. I need it. In general, the wider the pressure range that can be detected by a hydraulic sensor, the higher the cost. Therefore, controlling the variable valve mechanism using such a hydraulic sensor causes an increase in cost.

  The present invention has been made to solve the above-described problems, and even when a sensor having a relatively narrow detectable pressure range is used, the operation of the variable valve mechanism can be appropriately controlled. An object of the present invention is to provide a control device for a variable valve mechanism that can be used.

  In order to achieve the above object, the invention according to claim 1 is directed to a hydraulic oil pressurized by a hydraulic power source (hydraulic pump 11 in the embodiment (hereinafter, the same applies to this section)) driven by the internal combustion engine 3. A control device 1 for a variable valve mechanism that is driven by hydraulic pressure and controls the operation of a variable valve mechanism (cam phase variable mechanism 10) that can change the opening / closing timing of at least one of an intake valve 8 and an exhaust valve 9. Hydraulic oil temperature parameter detection means (water temperature sensor 21) for detecting hydraulic oil temperature parameter (engine water temperature TW) representing the temperature of hydraulic oil, and hydraulic pressure detection means (hydraulic sensor 23) for detecting hydraulic pressure of hydraulic oil (hydraulic pressure POIL). ), A rotational speed detection means (crank angle sensor 22) for detecting the rotational speed of the internal combustion engine 3 (engine rotational speed NE), and an upper limit based on the detected hydraulic oil temperature parameter. Upper limit rotational speed setting means (ECU2, step 1 in FIG. 3) for setting the rotational speed NEVTCH, and lower limit rotational speed setting means (ECU2, step 2 in FIG. 3) for setting the lower limit rotational speed NEVTCL based on the hydraulic oil temperature parameter ), The operation of the variable valve mechanism is permitted when the detected rotational speed of the internal combustion engine 3 is greater than the upper limit rotational speed NEVTCH, and the rotational speed of the internal combustion engine 3 is equal to or lower than the upper limit rotational speed NEVTCH. Control means (ECU 2, step 13 in FIG. 6) that permits the operation of the variable valve mechanism based on the detected hydraulic pressure of the hydraulic oil when it is larger than a number NEVTCL.

  This variable valve mechanism is driven by the hydraulic pressure of the hydraulic oil pressurized by the hydraulic source driven by the internal combustion engine, thereby changing the opening / closing timing of the intake valve and / or the exhaust valve. Further, according to the control device for the variable valve mechanism, when the upper limit rotational speed is set based on the detected hydraulic oil temperature parameter, and the detected rotational speed of the internal combustion engine is larger than the upper limit rotational speed. The operation of the variable valve mechanism is permitted. Since the hydraulic pressure source that pressurizes the hydraulic fluid is driven by the internal combustion engine, the hydraulic pressure of the hydraulic fluid changes according to the rotational speed of the internal combustion engine, and the higher the rotational speed, the higher the hydraulic pressure. Further, the hydraulic pressure of the hydraulic oil changes according to the temperature of the hydraulic oil, and becomes lower as the temperature of the hydraulic oil is higher. For this reason, the hydraulic pressure of the hydraulic oil is generally determined according to the rotational speed of the internal combustion engine and the temperature of the hydraulic oil. Therefore, as described above, the upper limit rotational speed is set based on the detected hydraulic oil temperature parameter, and when the rotational speed of the internal combustion engine is larger than the upper limit rotational speed, the hydraulic pressure of the hydraulic oil is sufficiently secured. In the state, the operation of the variable valve mechanism can be appropriately permitted.

  Further, the lower limit rotational speed is set based on the detected hydraulic oil temperature parameter, and is detected when the detected rotational speed of the internal combustion engine is equal to or lower than the upper limit rotational speed and greater than the lower limit rotational speed. The operation of the variable valve mechanism is permitted based on the hydraulic pressure of the hydraulic oil. When the rotational speed of the internal combustion engine is less than or equal to the upper limit rotational speed and greater than the lower limit rotational speed, whether or not the hydraulic pressure of the hydraulic oil is sufficiently secured is determined based on the rotational speed of the internal combustion engine and the temperature of the hydraulic oil. It cannot be determined accurately. Therefore, in this case, as described above, the operation of the variable valve mechanism is permitted based on the detected hydraulic pressure of the hydraulic oil, so that the variable hydraulic mechanism can be operated while the hydraulic pressure of the hydraulic oil is actually secured. The operation of the valve mechanism can be appropriately permitted.

  Further, as described above, in the range where the rotational speed of the internal combustion engine is larger than the upper limit rotational speed, the hydraulic pressure of the hydraulic oil is not used to determine whether or not the operation of the variable valve mechanism is permitted. Need not be detected by the hydraulic pressure detection means. Therefore, a large range of hydraulic oil pressure in which the rotational speed of the internal combustion engine exceeds the upper limit rotational speed can be excluded from the pressure range to be detected by the hydraulic pressure detection means. As a result, even when a pressure detection means having a relatively narrow pressure range to be detected is used, the operation of the variable valve mechanism can be appropriately controlled.

  The invention according to claim 2 is the control device 1 for the variable valve mechanism according to claim 1, wherein the control means operates the variable valve mechanism when the rotational speed of the internal combustion engine 3 is equal to or lower than the lower limit rotational speed NEVTCL. Is prohibited (step 58 in FIG. 7).

  If the rotational speed of the internal combustion engine is too low, pressurization by a hydraulic source driven by the internal combustion engine cannot be performed sufficiently, and the hydraulic pressure of the hydraulic oil is insufficient. According to this configuration, since the operation of the variable valve mechanism is prohibited when the detected rotational speed of the internal combustion engine is equal to or lower than the lower limit rotational speed, the operation of the variable valve mechanism in a state where the hydraulic oil pressure is insufficient. Can be avoided appropriately.

  According to a third aspect of the present invention, there is provided the variable valve mechanism control device 1 according to the first or second aspect, wherein the variable valve mechanism determination means (ECU2, FIG. 2) determines whether or not the variable valve mechanism is normal. 7) and target parameter setting means (ECU 2, step 21 in FIG. 5) for setting a target parameter (target cam phase CACMD) as a target of the opening / closing timing parameter representing the opening / closing timing changed by the variable valve mechanism. And an actual parameter detecting means (cam angle sensor 24) for detecting the opening / closing timing parameter as an actual parameter (cam phase CAEX), and the operation of the variable valve mechanism according to the hydraulic oil pressure is permitted by the control means. In this case, the variable valve mechanism determining means determines that the variable valve mechanism is normal, and the hydraulic pressure of the hydraulic oil detected by the hydraulic pressure detecting means is variable. When the value (cam phase deviation DCA) indicating the degree of deviation of the actual parameter from the target parameter is greater than a predetermined value (determination value CAJDG) that is equal to or greater than the lower limit value (operation limit hydraulic pressure POILLIM) that can drive the mechanism In addition, the apparatus further comprises failure determination means (ECU 2, FIG. 7) for determining that the hydraulic pressure detection means has failed.

  According to this configuration, it is determined whether or not the variable valve mechanism is normal, and the target parameter that is the target of the parameter that represents the opening and closing timing that is changed by the variable valve mechanism is set to represent the actual opening and closing timing. Detect parameters. Then, when the operation of the variable valve mechanism is permitted based on the hydraulic pressure of the hydraulic oil by the control means, it is determined that the variable valve mechanism is normal, and the hydraulic pressure of the hydraulic oil detected by the hydraulic pressure detection means is When the value representing the degree of deviation of the actual parameter from the target parameter is greater than a predetermined value that is greater than or equal to the lower limit value capable of driving the variable valve mechanism, it is determined that the hydraulic pressure detecting means has failed.

  When the variable valve mechanism is determined to be normal and the deviation of the actual parameter from the target parameter is high, the actual parameter does not follow the target parameter well, so the hydraulic oil pressure is actually insufficient. Presumed to be in a state. On the other hand, since the hydraulic pressure of the hydraulic oil detected by the hydraulic pressure detection means is equal to or higher than the lower limit value and does not indicate such a value, it can be appropriately determined that the hydraulic pressure detection means has failed.

  Further, in this determination method, the hydraulic pressure detection means uses existing parameters such as target parameters and actual parameters for controlling the variable valve mechanism and hydraulic oil pressure for controlling the operation of the variable valve mechanism. Therefore, it is possible to avoid an increase in cost for determining the failure.

It is a figure which shows roughly the control apparatus of the variable valve mechanism by embodiment of this invention with an internal combustion engine. It is a schematic diagram which shows schematic structure of a cam phase variable mechanism. It is a figure which shows the valve lift curve of an exhaust valve when a cam phase is set to the most retarded angle value (solid line) and the most advanced angle value (two-dot chain line) by the cam phase variable mechanism. It is a flowchart which shows an area | region determination process. It is a figure which shows an example of a TW-NE map. It is a flowchart which shows the operation permission determination process of a cam phase variable mechanism. It is a flowchart which shows the failure determination process of a hydraulic sensor. It is a flowchart which shows the convergence determination process of a cam phase.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration of a variable valve mechanism control apparatus 1 according to an embodiment of the present invention and an internal combustion engine (hereinafter referred to as “engine”) 3 to which the control apparatus 1 is applied. As shown in the figure, the control device 1 includes an ECU 2, which performs various control processes for the engine 3 such as a fuel injection control process for the internal combustion engine 3 as will be described later.

  The engine 3 is an in-line 4-cylinder (only one is shown) gasoline engine for a vehicle (not shown), and a combustion chamber 3c is formed between a piston 3a and a cylinder head 3b of each cylinder. A recess 3d is formed at the center of the upper surface of the piston 3a. A fuel injection valve 4 (hereinafter referred to as “injector 4”) and a spark plug 5 are attached to the cylinder head 3b so as to face the combustion chamber 3c, and fuel is directly injected into the combustion chamber 3c. That is, the engine 3 is an in-cylinder injection type.

  The injector 4 is disposed in the center of the top wall of the combustion chamber 3c and is connected to a high-pressure pump (not shown) through a fuel pipe (not shown). The fuel is boosted from a fuel tank (not shown) to a high pressure by this high-pressure pump, and then supplied to the injector 4 in a state of being regulated by a regulator (not shown). The fuel is injected from the injector 4 toward the concave portion 3d side of the piston 3a, and collides with the upper surface of the piston 3a including the concave portion 3d to form a fuel jet.

  The injector 4 is connected to the ECU 2, and, as will be described later, by controlling the valve opening timing and the valve closing timing by a drive signal from the ECU 2, the fuel injection amount corresponding to the valve opening time and the opening timing are controlled. The fuel injection time corresponding to the valve timing is controlled.

  The spark plug 5 is also connected to the ECU 2 and discharged when a high voltage is applied from the ECU 2 at a timing corresponding to the ignition timing IG, thereby burning the air-fuel mixture in the combustion chamber 3c.

  Further, the engine 3 is of the DOHC type and includes an intake camshaft 6 and an exhaust camshaft 7. These intake and exhaust camshafts 6 and 7 have an intake cam 6a and an exhaust cam 7a for opening and closing the intake valve 8 and the exhaust valve 9, respectively. The intake and exhaust camshafts 6 and 7 are connected to the crankshaft 3e via a timing belt (not shown), and rotate once every two rotations according to the rotation of the crankshaft 3e. A cam phase varying mechanism 10 is provided at one end of the exhaust camshaft 7.

  The cam phase variable mechanism 10 operates by being supplied with hydraulic pressure, and advances or retards the phase of the exhaust cam 7a with respect to the crankshaft 3e (hereinafter referred to as "cam phase CAEX") steplessly, thereby enabling the exhaust valve 9 Open / close timing is advanced or delayed. Thus, by increasing or decreasing the valve overlap between the intake valve 8 and the exhaust valve 9, the internal EGR amount is increased or decreased, and the charging efficiency is changed.

  As shown in FIG. 2, the cam phase varying mechanism 10 has an electromagnetic valve 10a. This solenoid valve 10a is a combination of a spool valve mechanism 10b and a solenoid 10c, and is connected to the advance chamber 15 and the retard chamber 16 via the advance oil passage 17a and the retard oil passage 17b, respectively. The hydraulic pressure POIL supplied from the hydraulic pump 11 is controlled and supplied to the advance chamber 15 and the retard chamber 16 as the advance hydraulic pressure Pad and the retard hydraulic pressure Prt, respectively. The solenoid 10c changes the advance hydraulic pressure Pad and the retard hydraulic pressure Prt by moving the spool valve body of the spool valve mechanism 10b within a predetermined range by the phase control input U_CAEX from the ECU 2.

  The hydraulic pump 11 is of a mechanical type connected to the crankshaft 3e, and sucks hydraulic oil stored in the oil pan 3f of the engine 3 through the oil passage 11a and boosts the pressure as the crankshaft 3e rotates. After that, the oil is supplied to the electromagnetic valve 10a through the oil passage 11a.

  In the cam phase variable mechanism 10 having the above-described configuration, while the hydraulic pump 11 is in operation, the solenoid valve 10a operates in accordance with the phase control input U_CAEX, so that the advance hydraulic pressure Pad is transferred to the advance chamber 15 and the retard hydraulic pressure Prt is changed. As a result, the above-described cam phase CAEX continuously changes between a predetermined maximum retardation value and a predetermined maximum advance angle value, whereby the valve of the exhaust valve 9 is supplied. The timing is changed steplessly between the most retarded timing shown by the solid line in FIG. 3 and the most advanced timing shown by the two-dot chain line.

  The hydraulic pressure POIL supplied from the hydraulic pump 11 to the cam phase variable mechanism 10 is detected by the hydraulic sensor 23, and the detection signal is sent to the ECU 2.

  A cam angle sensor 24 is provided at the end of the exhaust camshaft 7 opposite to the cam phase variable mechanism 10. The cam angle sensor 24 is composed of, for example, a magnet rotor and an MRE pickup, and outputs a CAM signal, which is a pulse signal, to the ECU 2 every predetermined cam angle (for example, 1 °) as the exhaust camshaft 7 rotates. . The ECU 2 obtains the actual cam phase CAEX from this CAM signal and the CRK signal and TDC signal described later.

  On the other hand, a magnet rotor 22a is attached to the crankshaft 3e. The magnet rotor 22a and the MRE pickup 22b constitute a crank angle sensor 22. The crank angle sensor 22 outputs a CRK signal and a TDC signal, which are pulse signals, with the rotation of the crankshaft 3e.

  The CRK signal is output every predetermined crank angle (for example, 30 °). The ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston 3a of each cylinder is at a predetermined crank angle position near the TDC (top dead center) at the start of the intake stroke, and in this example of the 4-cylinder type, every crank angle of 180 °. Is output.

  A water temperature sensor 21 is attached to the main body of the engine 3. The water temperature sensor 21 is composed of a thermistor, detects the engine water temperature TW, which is the temperature of the cooling water circulating in the main body of the engine 3, and sends the detection signal to the ECU 2.

  On the other hand, a throttle valve 13 is provided in the intake pipe 12 of the engine 3. An electric motor 13 a is connected to the throttle valve 13. The opening degree of the throttle valve 13 is controlled by the ECU 2 by controlling the electric motor 13 a according to the operating state of the engine 3, thereby controlling the amount of intake air to the engine 3.

  Further, the ECU 2 outputs a detection signal representing an operation amount (hereinafter referred to as “accelerator opening”) AP of an accelerator pedal (not shown) of the vehicle from the accelerator opening sensor 25.

  The ECU 2 includes a microcomputer (not shown) including a CPU 2a, a RAM 2b, a ROM 2c, an input / output interface (not shown), and the like. The detection signals of the sensors 21 to 25 described above are respectively input to the ECU 2, and after A / D conversion and shaping are performed by the input interface, are input to the CPU 2 a. In response to these input signals, the CPU 2a executes various arithmetic processes based on a control program stored in the ROM 2c.

  For example, the ECU 2 sets a target cam phase CACMD that is a target of the cam phase CAEX of the cam phase variable mechanism 10 according to the engine speed NE and the required torque PMCMD, and the detected cam phase CAEX is the target cam phase CACMD. The phase control input U_CAEX is calculated by feedback control so as to converge. The required torque PMCMD is calculated according to the engine speed NE and the accelerator pedal opening AP.

  In the present embodiment, the ECU 2 corresponds to an upper limit speed setting means, a lower limit speed setting means, a control means, a variable valve mechanism determination means, a target parameter setting means, and a failure determination means.

  Next, the operation permission determination process of the cam phase variable mechanism 10 executed by the ECU 2 will be described with reference to FIGS. This process is executed every predetermined time.

  FIG. 4 shows a TW-NE map used for determining permission of operation of the cam phase variable mechanism 10. As shown in FIG. 4, this TW-NE map shows an area defined by the engine water temperature TW and the engine speed NE (TW-NE area) as an upper limit speed NEVTCH and a lower limit speed NEVTCL obtained in advance through experiments. The two lines are divided into first to third regions VTCZONE1 to VTCZONE3.

  In the first region VTCZONE1 above the upper limit rotational speed NEVTCH, the engine rotational speed NE is relatively high with respect to the engine water temperature TW, so that an operating hydraulic pressure POIL sufficient to drive the cam phase variable mechanism 10 is secured. This corresponds to the area determined to be present. In the third region VTCZONE3 below the lower limit rotational speed NEVTCL, since the engine rotational speed NE is relatively low with respect to the engine water temperature TW, the operating oil pressure POIL is insufficient and the cam phase variable mechanism 10 is appropriately driven. This corresponds to an area where it is determined that the image cannot be recorded. Further, in the second region VTCZONE2 between the upper limit speed NEVTCH and the lower limit speed NEVTCL, the hydraulic pressure POIL for appropriately driving the cam phase variable mechanism 10 is secured from the engine water temperature TW and the engine speed NE. This corresponds to an area in which it cannot be determined clearly.

  Further, the higher the temperature of the hydraulic oil, the lower the viscosity of the hydraulic oil, and accordingly, the hydraulic pressure of the hydraulic oil is less likely to increase. Therefore, the upper limit rotational speed NEVTCH and the adjustable rotational speed NEVTCL are both the engine water temperature. The higher the TW, the larger the setting.

  FIG. 5 shows a TW-NE area determination process using this TW-NE map. In this process, first, in step 1 (illustrated as “S1”, the same applies hereinafter), an upper limit engine speed NEVTCH is calculated by searching a TW-NE map according to the detected engine water temperature TW. Next, a lower limit rotational speed NEVTCL is calculated by searching a TW-NE map according to the engine coolant temperature TW (step 2).

  Next, it is determined whether or not the detected engine speed NE is greater than the upper limit speed NEVTCH (step 3). If the answer is YES and NE> NEVTCH, it is determined that the engine speed NE is in the first region VTCZONE1, and the region number ZONENO is set to “1” to indicate that (step 4). The process ends.

  On the other hand, if the answer to step 3 is NO and NE ≦ NEVTCH, it is determined whether or not the engine speed NE is greater than the lower limit speed NEVTCL (step 5). If the answer is YES and NEVTCL <NE ≦ NEVTCH, it is determined that the engine speed NE is in the second region VTCZONE2, and the region number ZONENO is set to “2” to indicate that (step 6). This process is terminated.

  On the other hand, if the answer to step 5 is NO and NE ≦ NEVTCL, it is determined that the engine speed NE is in the third region VTCZONE3 (step 7), and the region number ZONENO is set to “3” to indicate that. To end the process.

  As described above, in the determination process of the TW-NE region, the upper limit rotational speed NEVTCH and the lower limit rotational speed NEVTCL are calculated based on the engine coolant temperature TW, and the relationship between the upper limit rotational speed NEVTTCH and the lower limit rotational speed NEVTCL is calculated. Then, it is determined whether the engine speed NE is in any of the first to third regions VTCZONE1 to VTCZONE1 to TW in the TW-NE region.

  FIG. 6 shows an operation permission determination process for determining permission / prohibition of the operation of the cam phase variable mechanism 10. In this process, first, in step 11, it is determined whether or not the region number ZONENO is “1”.

  If the answer is YES and the engine speed NE is in the first region VTCZONE1, whether or not the timer value TMDCA of the down-counting type response timer for measuring the elapsed time after the transition to the first region VTCZONE1 is 0 Is determined (step 12).

  If the answer is NO and the predetermined time T1 has not elapsed after the transition to the first region VTCZONE1, even if the engine speed NE is high, the delay in pressurization by the hydraulic pump 11 driven by the engine 3 Since there is a possibility that the operating oil pressure POIL is not sufficiently increased, the operation of the cam phase variable mechanism 10 is not permitted at this time, and the process proceeds to Step 15 described later. On the other hand, if the answer to step 12 is YES and the predetermined time T1 has elapsed after the transition to the first region VTCZONE1, it is assumed that the operating oil pressure POIL has increased sufficiently and the operation of the cam phase variable mechanism 10 is permitted. (Step 13), the process is terminated.

  On the other hand, if the answer to step 11 is NO and the region number ZONENO is not “1”, it is determined whether or not the region number ZONENO is “2” (step 14). If the answer is NO and the engine speed NE is in the third region VTCZONE3, the timer value TMDCA of the response timer described above is set to a predetermined time T1 (for example, 5 sec) (step 17) and the engine speed NE is low. Therefore, assuming that the operating oil pressure POIL is insufficient, the operation of the cam phase variable mechanism 10 is prohibited (step 18), and this process is terminated.

  When the answer to step 14 is YES and the engine speed NE is in the second region VTCZONE2 or when the answer to step 12 is NO, it is determined whether or not the hydraulic sensor failure flag F_OSNG is “1”. (Step 15). This hydraulic sensor failure flag F_OSNG is set to “1” when it is determined in the failure determination process described later that the hydraulic sensor 23 has failed.

  When the answer to step 15 is NO, that is, when the oil pressure sensor 23 is determined to be normal, it is determined whether or not the operating oil pressure POIL is equal to or greater than a predetermined operating limit oil pressure POILLIM (step 16). The operation limit oil pressure POILLIM is a lower limit value of the operation oil pressure POIL that can appropriately drive the cam phase variable mechanism 10, and is obtained in advance by experiments. If the answer to this step 16 is YES and POIL ≧ POILLIM, it is confirmed that a sufficient hydraulic pressure POIL is actually secured to drive, so the routine proceeds to step 13 where the cam phase variable mechanism 10 The operation is permitted and the process is terminated.

  On the other hand, when the answer to step 16 is NO, that is, when POIL <POILLIM, the operation hydraulic pressure POIL sufficient to drive the cam phase variable mechanism 10 is not actually ensured. Then, the operation of the cam phase variable mechanism 10 is prohibited, and this process is terminated.

  On the other hand, if the answer to step 15 is YES and it is determined that the hydraulic sensor 23 is malfunctioning, the determination in step 16 according to the detected hydraulic pressure POIL cannot be performed properly. Is skipped, the process proceeds to step 17 and step 18, the operation of the cam phase variable mechanism 10 is prohibited, and this process is terminated.

  As described above, in this operation permission determination process, when the engine speed NE is in the first region VTCZONE1 and the predetermined time T1 has elapsed after the transition to the first region VTCZONE1, the operating oil pressure POIL is sufficiently high. Assuming that it is secured, the operation of the cam phase varying mechanism 10 is permitted. Further, when the predetermined time T1 has not elapsed after the transition to the first region VTCZONE1 or when the engine speed NE is in the second region VTCZONE2, the detected hydraulic pressure POIL is equal to or higher than the operating limit hydraulic pressure POILLIM. In some cases, since it has been confirmed that a sufficient operating oil pressure POIL is actually secured, the operation of the cam phase variable mechanism 10 is permitted. When the operating oil pressure POIL is less than the operation limit oil pressure POILLIM, the cam phase variable mechanism 10 Prohibit operation. Further, when the engine speed NE is in the third region VTCZONE3, the operation of the cam phase variable mechanism 10 is prohibited because the hydraulic pressure POIL is insufficient.

  FIG. 7 shows a failure determination process for determining a failure of the hydraulic sensor 23. In this process, first, in step 21, it is determined whether or not the region number ZONENO is “1”. If the answer is YES and the engine speed NE is in the first region VTCZONE1, whether or not the timer value TMDCB of the down-counting type response timer for measuring the elapsed time after the transition to the first region VTCZONE1 is 0 Is discriminated (step 22). If the answer is NO and the predetermined time T2 has not elapsed, at this point, the failure determination of the hydraulic sensor 23 is suspended, and the hydraulic sensor failure flag F_OSNG is set to “0” (step 23). Exit.

  On the other hand, if the answer to step 22 is YES, it is determined whether or not the operating oil pressure POIL is greater than or equal to the operating limit oil pressure POILLIM (step 24). When this answer is NO and POIL <POILLIM, since the predetermined time T2 has elapsed after the transition to the first region VTCZONE1, the actual operating oil pressure should be equal to or higher than the operating limit oil pressure POILLIM. Since the hydraulic pressure POIL detected by the sensor 23 does not indicate such a value, it is determined that the hydraulic sensor 23 has failed, and the hydraulic sensor failure flag F_OSNG is set to “1” to indicate this. (Step 25), and this process is terminated.

  On the other hand, if the answer to step 24 is YES and POIL ≧ POILLIM, it is determined that the hydraulic sensor 23 is normal, step 23 is executed, and the process is terminated.

  If the answer to step 21 is NO and the engine speed NE is not in the first region VTCZONE1, the timer value TMDCB of the response timer described above is set to a predetermined time T2 (for example, 5 seconds) (step 26) and the region It is determined whether or not the number ZONENO is “2” (step 27). If the answer is NO and the engine speed NE is in the third region VTCZONE3, it is determined whether or not the operating oil pressure POIL is greater than or equal to the operating limit oil pressure POILLIM (step 28).

  When the answer is YES and POIL ≧ POILLIM, the engine speed NE is in the third region VTCZONE3, so that the actual operating oil pressure should be smaller than the operating limit oil pressure POILLIM, but is detected by the oil pressure sensor 23. Since the operating oil pressure POIL does not show such a value, it is determined that the oil pressure sensor 23 is out of order, the step 25 is executed, and the process is terminated.

  On the other hand, if the answer to step 28 is NO and POIL <POILLIM, it is determined that the hydraulic sensor 23 is normal, the hydraulic sensor failure flag F_OSNG is set to “0” in step 29, and this process ends.

  If the answer to step 27 is YES and the engine speed NE is in the second region VTCZONE2, it is determined whether or not the cam phase variable mechanism determination flag F_VTCOK is “1” (step 30). This cam phase variable mechanism determination flag F_VTCOK is set to “0” because the cam phase variable mechanism 10 is out of order when a signal indicating disconnection of the electromagnetic valve 10a of the cam phase variable mechanism 10 is detected. Otherwise, it is set to “1” as normal. If the answer to step 30 is NO and it is determined that the cam phase variable mechanism 10 has failed, the failure determination of the hydraulic sensor 23 is suspended, and the hydraulic sensor failure flag F_OSNG is set to “0” (step 31) The process is terminated.

  On the other hand, if the answer to step 30 is YES and it is determined that the cam phase variable mechanism 10 is normal, it is determined whether or not the operating oil pressure POIL is greater than or equal to the operating limit oil pressure POILLIM (step 32). If the answer is NO and POIL <POILLIM, the failure determination of the hydraulic sensor 23 is suspended, step 31 is executed, and this process is terminated.

  On the other hand, if the answer to step 32 is YES and POIL ≧ POILLIM, it is determined whether or not the cam phase convergence flag F_CAOK is “1” (step 33). This cam phase convergence flag F_CAOK is set to “1” when it is determined that the actual cam phase CAEX follows the target cam phase CACMD in the cam phase convergence determination process described later. Is. If the answer to step 33 is YES and the cam phase CAEX is following the target cam phase CACMD well, it is determined that the hydraulic sensor 23 is normal, step 31 is executed, and the present process is terminated. To do.

  On the other hand, when the answer to step 33 is NO, it is determined that the cam phase variable mechanism 10 is normal, and the actual cam phase CAEX does not follow the target cam phase CACMD well. Although the operating oil pressure POIL is estimated to be insufficient, the operating oil pressure POIL detected by the oil pressure sensor 23 indicates a value greater than or equal to the operating limit oil pressure POILLIM. Is determined to be malfunctioning. In order to express this, the hydraulic sensor failure flag F_OSNG is set to “1” (step 34), and this process is terminated.

  As described above, in this failure determination process, when the detected hydraulic pressure POIL is smaller than the operating limit hydraulic pressure POILLIM in the first region VTCZONE1, or when the hydraulic pressure POIL is equal to or higher than the operating limit hydraulic pressure POILLIM in the third region VTCZONE3. In the second region VTCZONE2, when the cam phase variable mechanism 10 is determined to be normal and the cam phase CAEX has not converged with respect to the target cam phase CACMD, the operating oil pressure POIL is greater than or equal to the operating limit oil pressure POILLIM In addition, it is determined that the hydraulic sensor 23 has failed.

  FIG. 8 shows cam phase convergence determination processing for setting the cam phase convergence flag F_CAOK. In this process, first, the absolute value of the difference between the target cam phase CACMD and the detected actual cam phase (actual cam phase) CAEX is calculated as the cam phase deviation DCA (step 41). Next, it is determined whether or not the calculated cam phase deviation DCA is greater than or equal to a predetermined determination value CAJDG (step 42).

  If the answer is NO and DCA <CAJDG, it is determined that the actual cam phase CAEX follows the target cam phase CACMD well, and the timer value TMDCC of the downcount timer is set to a predetermined time T3 (for example, 10 sec). (Step 43), the cam phase convergence flag F_CAOK is set to "1" (step 44), and this process is terminated.

  On the other hand, if the answer to step 42 is YES and DCA ≧ CAJDG, it is determined whether or not the timer value TMDCC is 0 (step 45).

  If the answer is NO and the predetermined time T3 has not elapsed after the DCA ≧ CAJDG is satisfied, for example, the actual cam phase CAEX is following the target cam phase CACMD that has been significantly changed. Since there is a possibility, step 44 is executed, and this process is terminated.

  On the other hand, when the answer to step 45 is YES, that is, when the state of DCA ≧ CAJDG continues for a predetermined time T3, it is determined that the actual cam phase CAEX does not follow the target cam phase CACMD well. Then, the cam phase convergence flag F_CAOK is set to “0” (step 46), and then this process is terminated. The cam phase convergence flag F_CAOK set as described above is used in step 33 of FIG.

  As described above, according to the present embodiment, the upper limit rotational speed NEVTCH is set based on the engine coolant temperature TW (step 1 in FIG. 3), and the first region VTCZONE1 in which the engine rotational speed NE is higher than the upper limit rotational speed NEVTCH. And when the predetermined time T1 has elapsed after the transition to the first region VTCZONE1, the operation of the cam phase variable mechanism 10 is permitted (steps 11 to 13 in FIG. 6). Therefore, the operation of the cam phase variable mechanism 10 can be appropriately permitted in a state where the operating oil pressure POIL is equal to or higher than the sufficiently high operation limit oil pressure POILLIM.

  Further, in this way, in the first region VTCZONE1, the hydraulic pressure POIL detected by the hydraulic pressure sensor 23 is not used when permitting the operation of the cam phase variable mechanism 10, so that the hydraulic pressure sensor having a relatively narrow pressure range is detected. Even in the case of using 23, the operation of the cam phase variable mechanism 10 can be appropriately controlled.

  Further, the lower limit rotational speed NEVTCL is set based on the engine coolant temperature TW (step 2 in FIG. 3), and when the engine rotational speed NE is in the third region VTCZONE3 equal to or lower than the lower limit rotational speed NEVTCL, the cam phase variable mechanism 10 Is prohibited (steps 14 and 18 in FIG. 6). Therefore, it is possible to appropriately avoid the operation of the cam phase variable mechanism 10 when the operating oil pressure POIL is smaller than the operation limit oil pressure POILLIM.

  Further, when the engine speed NE is in the second region VTCZONE2 that is equal to or lower than the upper limit speed NEVTCH and greater than the lower limit speed NEVTCL, and the operating oil pressure POIL detected by the oil pressure sensor 23 is equal to or higher than the operating limit oil pressure POILLIM, Since the operation of the cam phase variable mechanism 10 is permitted (steps 14, 16, and 13 in FIG. 6), the operation of the cam phase variable mechanism 10 is appropriately permitted in a state where a sufficient operating oil pressure POIL is actually secured. be able to.

  Further, it is determined that the cam phase variable mechanism 10 is normal, and the operating oil pressure POIL detected by the oil pressure sensor 23 is the operating limit oil pressure even though the actual cam phase CAEX does not follow the target cam phase CACMD. When POILLIM or more is indicated, it is determined that the hydraulic sensor 23 has failed (steps 30, 32 to 34 in FIG. 7). In this way, it is possible to appropriately determine a failure of the hydraulic sensor 23 using existing parameters, and to avoid an increase in cost for determining the failure.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, in the embodiment, the engine water temperature TW is used as the hydraulic oil temperature parameter, but other appropriate parameters representing the temperature of the hydraulic oil may be used. For example, the temperature of the hydraulic oil may be directly detected. Of course it is good.

  Further, although the cam phase CAEX is used as a parameter representing the valve timing changed by the cam phase variable mechanism 10, other appropriate parameters correlated with the valve timing may be used.

  Further, in the embodiment, the cam phase varying mechanism 10 is provided only on the exhaust side, but it may be provided only on the intake side or on both the intake side and the exhaust side. Further, the embodiment is an example in which the cam phase variable mechanism 10 that changes the cam phase CAEX is used as the variable valve mechanism for changing the opening / closing timing, but instead, it is driven by hydraulic pressure of hydraulic oil. Other types of variable valve mechanisms such as a variable valve mechanism that changes the valve lift stepwise and steplessly may be used.

  The embodiment is an example in which the present invention is applied to a gasoline engine mounted on a vehicle, but the present invention is not limited to this, and may be applied to various engines such as a diesel engine other than a gasoline engine. Also, the present invention can be applied to engines other than those for vehicles, for example, engines for marine propulsion devices such as outboard motors having a crankshaft arranged vertically. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Control apparatus of variable valve mechanism 2 ECU (Upper limit rotation speed setting means, lower limit rotation speed setting means, control means,
(Variable valve mechanism determination means, target parameter setting means, failure determination means)
3 Engine (Internal combustion engine)
8 Intake valve 9 Exhaust valve 10 Cam phase variable mechanism (variable valve mechanism)
11 Hydraulic pump (hydraulic power source)
21 Water temperature sensor (hydraulic oil temperature parameter detection means)
22 Crank angle sensor (rotation speed detection means, actual parameter detection means)
23 Hydraulic sensor (hydraulic detection means)
24 Cam angle sensor (actual parameter detection means)
TW engine water temperature (hydraulic oil temperature parameter)
POIL hydraulic pressure (hydraulic hydraulic pressure)
NE engine speed (speed of internal combustion engine)
NEVTCH Upper limit speed NEVTCL Lower limit speed CACMD Target cam phase (target parameter)
CAEX cam phase (actual parameter)
DCA cam phase deviation (value indicating the degree of deviation)
CAJDG judgment value (predetermined value)
POILLIM operation limit oil pressure (lower limit)

Claims (3)

A variable valve mechanism that is driven by the hydraulic pressure of hydraulic oil that is pressurized by a hydraulic source driven by an internal combustion engine and that controls the operation of a variable valve mechanism that can change the opening / closing timing of at least one of an intake valve and an exhaust valve. A control device,
Hydraulic oil temperature parameter detection means for detecting a hydraulic oil temperature parameter representing the temperature of the hydraulic oil;
Oil pressure detecting means for detecting the oil pressure of the hydraulic oil;
A rotational speed detection means for detecting the rotational speed of the internal combustion engine;
Based on the detected hydraulic oil temperature parameter, upper limit rotational speed setting means for setting an upper limit rotational speed,
Based on the hydraulic oil temperature parameter, lower limit rotation speed setting means for setting a lower limit rotation speed,
When the detected rotational speed of the internal combustion engine is larger than the upper limit rotational speed, the operation of the variable valve mechanism is permitted, the rotational speed of the internal combustion engine is equal to or lower than the upper limit rotational speed, and the lower limit rotational speed Control means for permitting the operation of the variable valve mechanism based on the detected hydraulic pressure of the hydraulic oil when greater than
The control apparatus of the variable valve mechanism characterized by including.   2. The control device for a variable valve mechanism according to claim 1, wherein the control means prohibits the operation of the variable valve mechanism when the rotation speed of the internal combustion engine is equal to or lower than the lower limit rotation speed. . Variable valve mechanism determining means for determining whether or not the variable valve mechanism is normal;
Target parameter setting means for setting a target parameter which is a target of the opening / closing timing parameter representing the opening / closing timing changed by the variable valve mechanism;
An actual parameter detecting means for detecting the opening / closing timing parameter as an actual parameter;
When the control means permits the operation of the variable valve mechanism based on the hydraulic pressure of the hydraulic oil, the variable valve mechanism determination means determines that the variable valve mechanism is normal, and the hydraulic pressure When the hydraulic pressure of the hydraulic oil detected by the detection means is equal to or greater than a lower limit value capable of driving the variable valve mechanism, and a value representing the degree of deviation of the actual parameter from the target parameter is greater than a predetermined value In addition, failure determination means for determining that the oil pressure detection means has failed,
The control apparatus for a variable valve mechanism according to claim 1 or 2, further comprising:

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