JP5482922B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine including a cooling device that circulates cooling water using a pump capable of changing a discharge amount without depending on an engine rotation speed.

  In recent years, in an internal combustion engine, a cooling device using a pump that can change a discharge amount without depending on an engine operating state such as an electric water pump has been put into practical use. In an internal combustion engine equipped with such a pump, for example, when the cooling water temperature is low, such as when the engine is warmed up, the pump discharge amount is limited to suppress heat exchange between the engine main body and the cooling water. It is made to promote (for example, refer patent document 1).

JP 2008-169750 A

  In an internal combustion engine, various controls are executed to maintain the engine operating state in an appropriate state. For example, an air-fuel ratio learning control that learns a steady deviation of the actual air-fuel ratio from the stoichiometric air-fuel ratio as an individual difference such as a fuel injection valve or a secular change, or a valve that improves the performance of an internal combustion engine by appropriately maintaining valve timing Examples of these include control of a timing variable mechanism.

  In such control, it is necessary to execute the control after grasping the temperature state of each part of the internal combustion engine. For example, in the air-fuel ratio control, when the warm-up of the internal combustion engine is not completed, it is greatly affected by the excessive adhesion of the injected fuel to the wall surface, incomplete combustion, etc. Is an inappropriate value for learning this as an individual difference of the fuel injection valve or the like. Further, in the control of the variable valve timing mechanism, the responsiveness to the control changes according to the temperature of the hydraulic oil. Therefore, it is necessary to grasp the temperature of the hydraulic oil when executing the control.

  Such a temperature state of each part of the internal combustion engine generally has a correlation with a detected value of the cooling water temperature, and is thus determined based on the cooling water temperature. However, in the period in which the pump discharge amount is limited to achieve early warm-up as described above, there is not necessarily a correlation between the detected value of the coolant temperature and the temperature state of each part of the internal combustion engine. For this reason, if the above control is performed in such a period, the control may be unreliable. Further, the control executed when the detected value of the cooling water temperature satisfies a predetermined condition may be executed at an inappropriate time.

  Such problems are not limited to air-fuel ratio learning control and valve timing variable mechanism control, but are generally common to various types of control of internal combustion engines that are affected by temperature conditions in various parts of the internal combustion engine. Yes.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to perform control with low reliability in an internal combustion engine in which the circulation of cooling water is restricted and the temperature environment is different from normal. The purpose is to prevent the control from being executed at an inappropriate time.

  In order to achieve the above object, the present invention changes an engine cooling system through which cooling water flows, a water temperature detection unit for detecting the temperature of the cooling water, and a discharge amount of the cooling water without depending on an engine operating state. An internal combustion engine comprising a pump capable of controlling the discharge amount of the pump so that the flow of the cooling water in the engine cooling system is restricted when compared with when the cooling water temperature is lower than the reference temperature In this control device, at least one of the engine controls is prohibited until the restriction on the circulation of the cooling water is released, and after the restriction on the circulation of the cooling water is released, the detected cooling water temperature is predetermined. The inhibition of the engine control is continued until the value converges and shifts to an equilibrium state.

  As described above, in the case of restricting the circulation, such as prohibiting the circulation of the cooling water in order to achieve early warm-up at the cold start or the like, unlike the case where the restriction of the circulation is not executed, The correlation between the temperature of the cooling water detected by the water temperature detector and the temperature at each part of the internal combustion engine is lowered. Further, by restricting the flow of the cooling water, there may be a temperature situation that does not occur during normal engine operation, such as a large temperature difference locally in the internal combustion engine. For this reason, when engine control is performed under such circumstances, depending on the contents of the engine control, the reliability of the control may be reduced, or this may be executed even though the control execution itself is unnecessary. Will be.

  According to this configuration, as described above, in an internal combustion engine in which the flow of cooling water is restricted and the temperature environment is different from normal, control with low reliability is performed, or control is performed at an inappropriate time. It can be avoided.

  Even after the restriction on the circulation of the cooling water is lifted, the degree is gradually relaxed until the cooling water circulates to some extent in the engine cooling system and the cooling water temperature shifts to an equilibrium state. Nevertheless, the internal combustion engine will be placed in a temperature environment different from normal. According to the present invention, it is possible to more reliably avoid execution of control with low reliability or execution of control at an inappropriate time.

1 is a schematic configuration diagram showing an internal combustion engine and a control device thereof in a first embodiment according to the present invention. The schematic block diagram of the cooling device of the internal combustion engine concerning the embodiment. The flowchart which shows the process sequence about the pump drive process concerning the embodiment. The flowchart which shows the process sequence about the air fuel ratio control concerning the embodiment. The graph which shows the relationship between the valve timing change speed and duty ratio about the valve timing variable mechanism concerning 2nd Embodiment. The flowchart which shows the process sequence about the valve timing control concerning the embodiment. The flowchart which shows the process sequence about the ignition timing control concerning 3rd Embodiment. The flowchart which shows the process sequence about the throttle opening reference position learning control concerning 4th Embodiment.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which a control device for an internal combustion engine according to the present invention is embodied will be described.
(First embodiment)
With reference to FIG. 1, the structure of the internal combustion engine concerning 1st Embodiment of this invention is demonstrated.

  As shown in FIG. 1, a plurality of cylinders 21 (only one of which is shown in FIG. 1) are formed in the cylinder block 11 of the internal combustion engine 1, and a piston 23 reciprocates inside the cylinders 21. It is provided to be movable. A cylinder head 12 is assembled to the upper part of the cylinder block 11, and an oil pan 14 for storing hydraulic oil is assembled to the lower part thereof. The combustion chamber 22 of the internal combustion engine 1 is defined by the top surface of the piston 23, the inner wall surface of the cylinder 21, and the lower surface of the cylinder head 12.

  A water jacket 52 is formed inside the cylinder block 11. The cylinder block 11 is provided with a water temperature sensor 92 for detecting the coolant temperature (hereinafter referred to as the coolant temperature THW). Note that this coolant temperature THW is used as an alternative value for each part of the internal combustion engine 1 and the temperature of the hydraulic oil because it has a correlation.

  In the intake passage 30 communicating with the combustion chamber 22, an electronically controlled throttle valve 60 is built in a throttle body 63 constituting a part thereof. The throttle valve 60 adjusts the amount of intake air introduced into the combustion chamber 22 (hereinafter referred to as intake air amount GA) by adjusting the opening (hereinafter referred to as throttle opening TA) by the motor 61. The throttle body 63 is provided with a restricting portion 64 that mechanically restricts the opening of the throttle valve 60 to a fully closed state, and a throttle sensor 96 that detects the opening TA.

  Further, the cylinder head 12 is provided with a fuel injection valve 26 that injects fuel toward the inside of the combustion chamber 22 and an ignition plug 27 that ignites the air-fuel mixture in the combustion chamber 22. When the piston 23 is pushed down by the combustion of the air-fuel mixture, the crankshaft 24 rotates and a driving force is obtained. The rotation speed of the crankshaft 24, that is, the engine rotation speed NE is detected by a crank angle sensor 98. On the other hand, a cam angle sensor 94 for detecting the rotational phase is provided in the vicinity of the intake camshaft 34. A knocking sensor 95 that detects knocking that occurs when the air-fuel mixture burns abnormally is attached in the vicinity of the combustion chamber 22.

  An exhaust gas purification catalyst 41 for purifying exhaust gas is provided in the exhaust passage 31 communicating with the combustion chamber 22. The exhaust purification catalyst 41 oxidizes hydrocarbons (HC) and carbon monoxide (CO) in the exhaust and nitrogen oxides (NOx) in the exhaust in a state where combustion near the stoichiometric air-fuel ratio is performed. It has the function of purifying exhaust gas by reducing exhaust gas. In the exhaust passage 31, an air-fuel ratio sensor 97 for detecting the oxygen concentration DO in the exhaust is attached in the vicinity of the exhaust purification catalyst 41.

  Further, the cylinder head 12 is provided with an intake valve 32 for communicating / blocking the combustion chamber 22 and the intake passage 30 and an exhaust valve 33 for communicating / blocking the combustion chamber 22 and the exhaust passage 31 so as to reciprocate. ing. The intake valve 32 and the exhaust valve 33 are respectively opened and closed by an intake camshaft 34 and an exhaust camshaft 35 that rotate in synchronization with the crankshaft 24. The intake camshaft 34 is provided with a variable valve timing mechanism 70 that adjusts the relative rotational phase with respect to the crankshaft 24 to advance or retard the valve timing of the intake valve 32.

  The variable valve timing mechanism 70 is supplied with hydraulic oil through a hydraulic circuit 71. The advance side oil passage 72 and the retard angle side oil passage 73 constituting a part of the hydraulic circuit 71 connect the variable valve timing mechanism 70 and the oil control valve 74, respectively. The hydraulic circuit 71 includes a supply passage 76 and a discharge passage 77 that are connected to the oil control valve 74 at one end. The other ends of the supply passage 76 and the discharge passage 77 are connected to the oil pan 14. An oil pump 75 that discharges the hydraulic oil of the oil pan 14 toward the oil control valve 74 is provided in the supply passage 76.

  The oil control valve 74 displaces the spool (not shown) based on the duty ratio DVT of the drive signal output from the electronic control unit 91, thereby changing the supply / discharge state of the hydraulic oil to the valve timing variable mechanism 70. Control. In other words, the supply state and discharge state of the hydraulic oil in the advance side oil passage 72 and the retard side oil passage 73 are controlled.

  The electronic control unit 91 captures detection values of various sensors such as a water temperature sensor 92, a cam angle sensor 94, a knocking sensor 95, a throttle sensor 96, an air-fuel ratio sensor 97, a crank angle sensor 98, and an accelerator sensor 99 connected thereto. At the same time, various controls such as fuel injection control, ignition timing control, and throttle opening control are executed based on the detection values of these sensors.

  Next, the cooling device 50 for the internal combustion engine 1 will be described with reference to FIG. The cooling device 50 includes an electric water pump 56, a cooling water passage 53 including a water jacket 52, a water temperature sensor 92 that detects a cooling water temperature THW, a radiator 51, and a thermostat 57. The throttle body 63 is formed with a flow passage 53 a that constitutes a part of the cooling water passage 53.

  The cooling water passage 53 as an engine cooling system includes a bypass passage 55 that bypasses the radiator 51, and a thermostat 57 is provided at the downstream end of the bypass passage 55. This thermostat 57 is a temperature-sensitive type in which the position of a valve provided therein changes according to the cooling water temperature THW, and in the cooling water passage 53, from the downstream side portion of the radiator 51 to the upstream side portion of the water pump 56. The flow rate of the cooling water flowing through the radiator 51 is adjusted by changing the communication state of the portion that reaches the position. That is, when the cooling water temperature THW is low, the inflow of cooling water from the radiator 51 to the water jacket 52 is prohibited, and the inflow of cooling water from the bypass passage 55 to the water jacket 52 is permitted. On the other hand, when the coolant temperature THW increases, the coolant water is allowed to flow from the radiator 51 to the water jacket 52. In other words, the cooling water discharged from the water pump 56 to the water jacket 52 is returned again to the water pump 56 via the radiator 51. As a result, in the radiator 51, heat exchange is performed between the cooling water and the outside air, and the cooling water temperature THW is lowered.

  By the way, after the engine is started, it is desirable to complete the warm-up of the internal combustion engine 1 at an early stage in order to improve fuel consumption and combustion stability. Therefore, in the cooling device 50 of the present embodiment, the drive of the water pump 56 is stopped until the warm-up of the internal combustion engine 1 is completed, and the circulation of the cooling water in the cooling water passage 53 is prohibited.

  Hereinafter, a specific processing procedure of drive control in the water pump 56 will be described with reference to FIG. This process is repeatedly performed by the electronic control unit 91 every predetermined calculation cycle.

  First, the electronic control unit 91 determines whether or not the cooling water temperature THW detected by the water temperature sensor 92 is lower than the reference temperature TX (step S110). The reference temperature TX is a value for determining whether or not the warm-up of the internal combustion engine 1 has been completed, and is set in advance to a value lower than the valve opening temperature of the thermostat 57.

  If the electronic control unit 91 determines that the coolant temperature THW is equal to or higher than the reference temperature TX (step S110: NO), the electronic control unit 91 drives the water pump 56 (step S130). Incidentally, in this case, the electronic control unit 91 changes the discharge amount of the water pump 56 in accordance with the coolant temperature THW.

  On the other hand, when it is determined that the coolant temperature THW is lower than the reference temperature TX (step S110: YES), the driving of the water pump 56 is stopped (step S120). That is, when the engine is started under the condition that the cooling water temperature THW is lower than the reference temperature TX, such as when the engine is cold, the water pump 56 is maintained in a state where its driving is stopped. The electronic control unit 91 quickly completes warming up of the internal combustion engine 1 through such control.

  Incidentally, the electronic control unit 91 feedback corrects the fuel injection amount and the like so that the air-fuel ratio of the air-fuel mixture burned based on the oxygen concentration DO in the exhaust detected by the air-fuel ratio sensor 97 becomes the stoichiometric air-fuel ratio, An air-fuel ratio control process for updating the air-fuel ratio learning value KG is performed based on the air-fuel ratio correction coefficient FAF corresponding to the feedback correction amount. The renewal of the air-fuel ratio learning value KG is a value corresponding to the steady degree of deviation between the theoretical air-fuel ratio and the actual air-fuel ratio that is generated due to individual differences between the engines. Completed and should be done when the internal combustion engine is in normal operating conditions.

  In this respect, when the driving of the water pump 56 is stopped, a large temperature difference is locally generated in each part of the internal combustion engine 1, and the cooling water is circulated during normal engine operation, that is, the internal combustion engine 1 and the like. Sometimes a temperature condition will not occur. For this reason, when the driving of the water pump 56 is stopped, there is a possibility that an inappropriate value as the steady deviation between the theoretical air-fuel ratio and the actual air-fuel ratio is updated as the air-fuel ratio learning value KG. . For example, in a normal operation state, when the coolant temperature THW is equal to or higher than a certain value, it can be assumed that the temperature inside the combustion chamber 22 also increases according to the coolant temperature THW. However, when the driving of the water pump 56 is stopped, such a correlation is almost lost. For example, even if the cooling water temperature THW is equal to or higher than a certain value, the temperature of the combustion chamber 22 hardly increases, and the wall surface of the combustion chamber 22 There may be a situation where a large amount of fuel adheres. For this reason, in the present embodiment, when the driving of the water pump 56 is stopped, the air-fuel ratio learning value KG is not updated. Hereinafter, the execution procedure of the air-fuel ratio control process in the present embodiment will be described with reference to FIG.

In this process, first, the basic fuel injection amount QBASE is calculated based on the engine rotational speed NE and the engine load calculated from the intake air amount GA (step S210).
Next, the air-fuel ratio correction coefficient FAF is calculated based on the detection value of the air-fuel ratio sensor 97 (step S220). This air-fuel ratio correction coefficient FAF compensates for a temporary divergence between the reference oxygen concentration, which is the oxygen concentration of the exhaust gas when the actual air-fuel ratio is the stoichiometric air-fuel ratio, and the actual oxygen concentration DO detected by the air-fuel ratio sensor 97. To do. That is, when the oxygen concentration DO detected by the air-fuel ratio sensor 97 is lower than the reference oxygen concentration, that is, when the actual air-fuel ratio is on the rich side, the air-fuel ratio correction coefficient FAF is less than the reference value “1.0”. Is also changed to a smaller value. In this case, the air-fuel ratio correction coefficient FAF is changed to be smaller in proportion to the degree of deviation of the actual air-fuel ratio calculated from the oxygen concentration DO with respect to the theoretical air-fuel ratio. On the other hand, when the oxygen concentration DO detected by the air-fuel ratio sensor 97 is higher than the reference oxygen concentration, that is, when the actual air-fuel ratio is on the lean side, the air-fuel ratio correction coefficient FAF is less than the reference value “1.0”. Is also changed to a larger value. In this case, the air-fuel ratio correction coefficient FAF is changed so as to increase in proportion to the degree of deviation of the actual air-fuel ratio calculated from the oxygen concentration DO with respect to the theoretical air-fuel ratio.

Next, it is determined whether or not the water pump 56 is in a driving state (step S230).
If it is determined that the water pump 56 is operating (step S230: YES), the average value FAFAV of the air-fuel ratio correction coefficient FAF is then calculated (step S240). Then, it is determined whether or not the average value FAFAV of the air-fuel ratio correction coefficient FAF exceeds a predetermined value α (> 1.0) (step S242). If the average value FAFAV exceeds the predetermined value α (step S242: YES), the air-fuel ratio learning value KG is updated based on the following equation (1) (step S244).

KG ← KG-a (1)

In the above equation (1), “a (> 0)” is a predetermined correction value, which is set to a smaller value than the amount of change in the air-fuel ratio correction coefficient FAF.

  On the other hand, when the average value FAFAV is less than the predetermined value α (step S242: NO), it is further determined whether or not the average value FAFAV is less than the predetermined value β (<1.0) (step S252). If the average value FAFAV is less than the predetermined value β (step S252: YES), the air-fuel ratio learning value KG is updated based on the following equation (2) (step S254).

KG ← KG + b (2)

In the above equation (2), “b (> 0)” is a predetermined correction value, and is set to a small value as compared with the change amount of the air-fuel ratio correction coefficient FAF as in the previous correction value a. ing.

  When the average value FAFAV of the air-fuel ratio correction coefficient FAF is in the range of (β ≦ FAFAV ≦ α) (step S242: NO, step S252: NO), or when the air-fuel ratio learning value KG is updated (steps S244, S254) ), The final fuel injection amount QFIN is calculated based on the following equation (3) (step S270).

QFIN ← QBASE / FAF / KG / K (3)

Here, “K” on the right side of the above equation (3) indicates other correction coefficients such as an increase at start-up.

  On the other hand, when it is determined in the previous step S230 that the driving of the water pump 56 is stopped, that is, the warm-up is not completed, the circulation of the cooling water in the cooling water passage 53 is prohibited. If it is determined (step S230: NO), the air / fuel ratio learned value KG learned so far is set as the air / fuel ratio learned value KG (step S260). As described above, when the driving of the water pump 56 is stopped and the circulation of the cooling water in the cooling water passage 53 including the water jacket 52 of the internal combustion engine 1 is prohibited, the air-fuel ratio learning value KG is updated. Instead, the final fuel injection amount QFIN is calculated using the updated air-fuel ratio learning value KG during the previous normal operation, that is, when the water pump 56 is driven and the prohibition of the circulation of the cooling water is released.

  The electronic control unit 91 calculates the fuel injection time TAU based on the final fuel injection amount QFIN, and drives the fuel injection valve 26 to open based on the fuel injection time TAU. As a result, an amount of fuel corresponding to the final fuel injection amount QFIN is injected from the fuel injection valve 26.

According to this embodiment described above, the following effects can be obtained.
(1) If the water pump 56 is stopped to prevent the internal combustion engine 1 from warming up at the time of cold start or the like and the flow of cooling water is prohibited, the water pump 56 is driven and cooled. Unlike the case where water is circulated, there may be a temperature state that does not occur during normal engine operation, such as a large temperature difference locally in the internal combustion engine 1. When the air-fuel ratio learning control is performed under such a situation, for example, the air-fuel ratio learning value KG is learned under a state where the amount of fuel adhering to the combustion chamber 22 is extremely large. There is a possibility that an unsuitable value as the degree of steady deviation from the air-fuel ratio is learned as the air-fuel ratio learning value KG, and the reliability of the control is lowered. According to this embodiment, since the air-fuel ratio learning value KG is not updated during the period when the driving of the water pump 56 is stopped, the air-fuel ratio is determined based on the air-fuel ratio learning value KG with low reliability. It is possible to avoid the control being performed.

(Second Embodiment)
A second embodiment according to the present invention will be described focusing on differences from the first embodiment with reference to FIGS. Note that the same reference numerals are assigned to the same components as those in the first embodiment, and detailed description thereof is omitted.

  As shown in FIG. 1, hydraulic oil is supplied to the variable valve timing mechanism 70 through a hydraulic circuit 71. The oil control valve 74 changes the communication state of the supply passage 76 and the discharge passage 77 with the advance angle side oil passage 72 and the retard angle side oil passage 73, thereby supplying and discharging the hydraulic oil to the variable valve timing mechanism 70. To control.

  That is, when the retard angle side oil passage 73 and the discharge passage 77 communicate with each other and the advance angle side oil passage 72 and the supply passage 76 communicate with each other, the oil pump 14 is driven to advance the hydraulic oil in the oil pan 14. The hydraulic oil in the retard side oil passage 73 is returned to the oil pan 14 while being sent out to the corner side oil passage 72. As a result, the variable valve timing mechanism 70 is driven to advance the relative rotation phase of the intake camshaft 34 with respect to the crankshaft 24, and the valve timing of the intake valve 32 is advanced.

  On the other hand, when the retard angle side oil passage 73 and the supply passage 76 are communicated with each other by the oil control valve 74 and the advance angle side oil passage 72 and the discharge passage 77 are communicated, the oil pan 14 is driven by the oil pump 75. The hydraulic oil is sent out to the retard side oil passage 73 and the hydraulic oil in the advance side oil passage 72 is returned to the oil pan 14. As a result, the variable valve timing mechanism 70 is driven so as to retard the relative rotational phase of the intake camshaft 34 with respect to the crankshaft 24, and the valve timing of the intake valve 32 is retarded.

  FIG. 5 shows the relationship between the duty ratio DVT in the drive signal when driving the oil control valve 74 and the valve timing changing speed. Note that the solid line LP1, the one-dot chain line LP2, and the two-dot chain line LP3 indicate transitions when the hydraulic oil temperature THO is estimated to be higher in that order. That is, the solid line LP1 shows the transition when the hydraulic oil temperature THO is the highest, the one-dot chain line LP2 shows the transition when the hydraulic oil temperature THO is lower than this, and the two-dot chain line shows the transition when the LP3 has the lowest hydraulic oil temperature THO.

  As shown in FIG. 5, when the valve timing is retarded, the amount of hydraulic oil supplied to the retard angle side oil passage 73 increases as the duty ratio DVT approaches “0%”, and therefore a larger change speed. The valve timing is retarded. On the other hand, when the valve timing is advanced, the amount of hydraulic oil supplied to the advance side oil passage 72 increases as the duty ratio DVT approaches 100%. Therefore, the valve timing is advanced at a higher change speed. Become so.

  As shown in FIG. 5, for example, when the valve timing is advanced, the duty ratio DVT of the drive signal corresponding to the change timing of the valve timing is set to a larger value as the hydraulic oil temperature THO is lower. On the other hand, when the valve timing is retarded, the duty ratio DVT of the drive signal corresponding to the change timing of the valve timing is set to a smaller value as the hydraulic oil temperature THO is lower. That is, the lower the hydraulic oil temperature THO, the higher the viscosity of the hydraulic oil and the lower the responsiveness when supplying and discharging the hydraulic oil to the variable valve timing mechanism 70. In order to compensate for this, the duty ratio The DVT is corrected based on the hydraulic oil temperature THO. Normally, the hydraulic oil temperature THO has a high correlation with the cooling water temperature THW, so the hydraulic oil temperature THO is estimated from the cooling water temperature THW. However, when the driving of the water pump 56 is stopped as described above, the correlation between the coolant temperature THW and the hydraulic fluid temperature THO is lost, and thus correction based on the hydraulic fluid temperature THO (coolant coolant temperature THW) is prohibited. Like to do.

Hereinafter, the processing procedure of the valve timing control will be described with reference to FIG. This process is repeatedly performed by the electronic control unit 91 every predetermined calculation cycle.
First, the electronic control unit 91 calculates a target valve timing based on the engine operating state (step S310). Specifically, in a low rotation / low load range such as when the engine is started or during idling, the amount of exhaust gas that is reboiled into the combustion chamber 22 by reducing the valve overlap amount between the intake valve 32 and the exhaust valve 33. By reducing this, the combustion is stabilized. On the other hand, in a medium load region such as when starting acceleration, the valve overlap is increased by advancing the intake valve 32 to reduce the pumping loss.

  Next, the duty ratio DVT in the drive signal of the oil control valve 74 is calculated from the deviation between the target valve timing and the actual valve timing detected from the cam angle sensor 94 and the crank angle sensor 98 with reference to the calculation map. (Step S320).

  For example, when the actual valve timing is on the retard side with respect to the target valve timing, the duty ratio DVT is set to a value in the range of 50% <DVT ≦ 100% in order to advance the valve timing. Here, as the deviation between the target valve timing and the actual valve timing is larger, the duty ratio DVT is set to a relatively large value in the above range. Therefore, as shown in FIG. 5, the valve timing is advanced with a larger change speed. On the other hand, when the deviation between the target valve timing and the actual valve timing is small, the duty ratio DVT is set to a relatively small value in the above range. Therefore, the change speed of the valve timing is reduced, and the stability when the actual valve timing is converged to the target valve timing is improved.

  On the other hand, when the actual valve timing is on the advance side with respect to the target valve timing, the duty ratio DVT is set to a value in the range of 0% ≦ DVT <50% in order to retard the valve timing. The Here, the duty ratio DVT is set to a relatively small value in the above range as the deviation between the target valve timing and the actual valve timing increases. Therefore, as shown in FIG. 5, the valve timing is retarded with a larger change speed. On the other hand, when the deviation between the target valve timing and the actual valve timing is small, the duty ratio DVT is set to a relatively large value in the above range. Accordingly, as in the case where the valve timing is advanced, the change speed is reduced, and the stability when the actual valve timing is converged to the target valve timing is improved.

  When the valve timing is changed in this way and the deviation from the target valve timing becomes extremely small, the duty ratio DVT is set to 50%. In this case, the supply and discharge of the hydraulic fluid to the variable valve timing mechanism 70 is stopped, and the valve timing is maintained as it is.

  Next, it is determined whether or not the water pump 56 is in a driving state (step S330). When it is determined that the water pump 56 is driven (step S330: YES), the previously calculated duty ratio DVT is corrected based on the coolant temperature THW correlated with the hydraulic oil temperature THO. Specifically, when the coolant temperature THW is low and the viscosity of the hydraulic oil is high, the duty ratio DVT is corrected based on the following equations (4) and (5).

DVT ← DVT + ΔDL1 (4)
(50% <DVT ≦ 100%)
DVT ← DVT−ΔDL1 (5)
(0% ≦ DVT <50%)

Here, “ΔDL1” is a function of the cooling water temperature THW, and is set to a larger value as the cooling water temperature THW is lower.

On the other hand, when the coolant temperature THW is high and the viscosity of the hydraulic oil is low, the duty ratio DVT is corrected based on the following equations (6) and (7).

DVT ← DVT−ΔDL2 (6)
(50% <DVT ≦ 100%)
DVT ← DVT + ΔDL2 (7)
(0% ≦ DVT <50%)

Here, “ΔDL2” is a function of the cooling water temperature THW, and is set to a larger value as the cooling water temperature THW is higher.

  In this way, by correcting the duty ratio DVT based on the coolant temperature THW, the operation responsiveness of the variable valve timing mechanism 70 is kept constant regardless of the viscosity even when the viscosity of the hydraulic oil is different. Will be able to.

  On the other hand, when it is determined that the water pump 56 is in a stopped state (step S330: NO), this process is terminated without performing the correction process based on the cooling water temperature THW described above. That is, when the correlation between the coolant temperature THW and the hydraulic oil temperature THO is low and the operation responsiveness of the variable valve timing mechanism 70 cannot be estimated by the coolant temperature THW, correction processing with low reliability is not executed. This is prohibited.

According to this embodiment described above, the following effects can be obtained.
(2) When driving of the water pump 56 is stopped, the correlation between the coolant temperature THW and the hydraulic oil temperature THO may decrease. Under such circumstances, when the duty ratio DVT for driving the variable valve timing mechanism 70 is corrected based on the coolant temperature THW, the reliability of the control may be reduced. According to the present embodiment, when the driving of the water pump 56 is stopped, the duty ratio DVT for driving the oil control valve 74 based on the cooling water temperature THW is not corrected, so that the variable valve timing mechanism It becomes possible to suppress a decrease in the reliability of the control 70.

(Third embodiment)
Next, a third embodiment according to the present invention will be described with reference to FIG. 7 focusing on differences from the first embodiment. Note that the same reference numerals are assigned to the same components as those in the first embodiment, and detailed description thereof is omitted.

  In the ignition timing control, when it is determined that knocking has occurred based on the detection value of the knocking sensor 95, the ignition timing is retarded until a limit timing at which knocking does not occur. On the other hand, when it is determined that knocking has not occurred, an ignition timing setting process for advancing the ignition timing to the limit timing at which knocking occurs is performed. Thus, learning is performed such that the amount of advance is possible without causing knocking as the advance learning amount. Such an advance learning amount depends on, for example, the amount of deposit adhering to the inner wall of the combustion chamber 22 (in other words, the amount of change over time in the compression ratio), the change over time in the spray form of the fuel injected from the fuel injection valve 26, and the like. Will be different. Therefore, by learning this advance angle learning amount in advance, it becomes possible to set the ignition timing to a more advanced timing without causing knocking, and for example, the engine output can be improved. It becomes like this.

  However, when the driving of the water pump 56 is stopped and the circulation of the cooling water is prohibited, the temperature state of the internal combustion engine 1, particularly the temperature state in which the temperature state in the combustion chamber 22 does not occur during normal engine operation. May be. If the advance learning amount described above is learned under such circumstances, the combustion state of the internal combustion engine 1 may be warped and deteriorated. Therefore, in the present embodiment, when the driving of the water pump 56 is stopped, learning of the advance learning amount is prohibited.

Hereinafter, the processing procedure of the ignition timing control in the present embodiment will be described with reference to FIG. This process is repeatedly performed by the electronic control unit 91 every predetermined calculation cycle.
When this process is started, the electronic control unit 91 calculates the basic ignition timing θBASE and the maximum retard amount θMAX based on the engine speed NE and the engine load (step S405). Here, the basic ignition timing θBASE is a timing at which the largest engine output is obtained in the engine operating state. On the other hand, the maximum retard amount θMAX is a retard amount for retarding the basic ignition timing θBASE until a timing at which knocking cannot be assumed even when various situations are considered in the operating state. That is, if the ignition timing is set to (θBASE + θMAX), the engine output is reduced, but the occurrence of knocking can be reliably prevented.

  Here, if it is determined that the water pump 56 is in a driving state, that is, the cooling water is being circulated (step S410: YES), it is next determined whether or not the knocking determination flag FKNOCK is “1”. Judgment is made (step S430). This knocking determination flag FKNOCK is set through other determination processing, and is set based on whether knocking frequently occurs or whether a state in which knocking does not occur continues. .

  When it is determined that the knocking determination flag FKNOCK is “1” (step S430: YES), retardation correction is performed. Specifically, when knocking occurs repeatedly, a predetermined correction amount γ1 is subtracted from the current advance angle learning amount θG and set as a new advance angle learning amount θG (step S440). This correction amount β1 is a preset value. On the other hand, when it is determined that the knocking determination flag FKNOCK is not “1” (step S430: NO), advance angle correction is performed. Specifically, when the state where knocking does not occur continues, a predetermined correction amount γ2 is added to the current advance learning amount θG, and this is set as a new advance learning amount θG. (Step S450). This correction amount γ2 is a value that is set in advance, which is extremely smaller than the previous correction amount γ1.

Then, after calculating the advance learning amount θG in this way, the final ignition timing θFIN is calculated based on the following equation (8) (step S470).

θFIN ← θBASE + θMAX−θG (8)

In step S410, when it is determined that the water pump 56 is not in a driving state, that is, the cooling water is not circulated (step S410: NO), the advance learning amount θG is set to “0”. Setting is made (step S460). That is, since the cooling water is not circulated, the temperature distribution in the combustion chamber 22 and the combustion state of the air-fuel mixture vary from time to time, so that abnormal combustion such as knocking by advancing the ignition timing occurs. Therefore, the final ignition timing θFIN is set to (θBASE + θMAX) from the above equation (8).

According to this embodiment described above, the following effects can be obtained.
(3) When the drive of the water pump 56 is stopped, unlike when the water pump 56 is driven, a large temperature difference locally occurs in the combustion chamber 22, and the state of the combustion chamber 22 is during normal engine operation. The temperature may not occur. When the advance angle learning amount θG is learned under such circumstances, an inappropriate value is set as the advance angle learning amount θG, and the combustion state of the internal combustion engine 1 may be warped and deteriorated. According to the present embodiment, when the drive of the water pump 56 is stopped, the advance learning amount θG is set to “0”, and the ignition timing is retarded to the maximum retard timing. It is possible to suppress deterioration of the combustion state of the internal combustion engine 1 by setting an inappropriate value for θG.

(Fourth embodiment)
Hereinafter, a fourth embodiment according to the present invention will be described with reference to FIG. 8 focusing on differences from the first embodiment. Note that the same reference numerals are assigned to the same components as those in the first embodiment, and detailed description thereof is omitted.

  In the throttle sensor 96, there is an error in detecting the throttle opening degree TA due to individual differences and the like, and such a detection error causes a decrease in accuracy in controlling the throttle opening degree TA. Therefore, in the present embodiment, the opening degree of the throttle valve 60 is mechanically restricted through the restriction unit 64, and the detected value of the throttle sensor 96 detected under the condition is used as a reference when the throttle valve 60 is in the fully closed state. It learns as a value (throttle opening reference position learning control).

  However, since the output characteristic of the throttle sensor 96 has temperature dependence, such a throttle is stopped in a state where the driving of the water pump 56 is stopped and the flow of the cooling water in the flow passage 53a of the throttle body 63 is stopped. Even if the reference opening degree of the valve 60 is learned, the learning result is that the opening degree control of the throttle valve 60 in the normal engine operating state, that is, the state where the cooling water is flowing through the flow passage 53a of the throttle body 63. It will not conform to. For this reason, in this embodiment, when the water pump 56 is not driven and the circulation of the cooling water is stopped, such throttle opening reference position learning control is prohibited.

  Hereinafter, the throttle opening reference position learning control according to the present embodiment will be described with reference to FIG. This process is repeatedly performed by the electronic control unit 91 every predetermined calculation cycle.

  In this process, it is first determined whether or not the water pump 56 is in a driving state (step S510). If it is determined that the water pump 56 is operating (step S510: YES), it is next determined whether or not the fully closed position learning is completed (step S520). If it is determined that the reference position learning has not been completed (step S520: YES), the motor 61 is driven and the opening degree of the throttle valve 60 is maintained in a state that is mechanically regulated by the regulating unit 64. Then, the electronic control unit 91 learns the output value of the throttle sensor 96 at this time as a value (throttle opening TA) corresponding to the fully closed state of the throttle valve 60 (step S540). On the other hand, when it is determined that the reference position learning has already been completed (step S520: NO), normal opening / closing control is executed for the throttle valve 60 (step S530).

  Further, when it is determined in step S510 that the driving of the water pump 56 is stopped (step S510: NO), normal opening / closing control is executed for the throttle valve 60 (step S530). That is, the reference position learning in step S540 is not executed.

According to this embodiment described above, the following effects can be obtained.
(4) When the drive of the water pump 56 is stopped, unlike when the water pump 56 is driven, it does not occur during normal engine operation, such as a local temperature rise in the throttle valve 60 or the throttle sensor 96. Temperature conditions may occur. When the throttle opening reference position learning control is performed in such a situation, an inappropriate value is learned as the reference position (fully closed position) of the throttle valve 60, and the reliability of the throttle opening control is lowered. There is a risk that. According to the present embodiment, when the driving of the water pump 56 is stopped, the throttle opening reference position learning control is not performed, so that it is possible to suppress the control with low reliability. become able to.

  In addition, embodiment described above can be implemented in the aspect which changed the form suitably as follows. In addition, the above-described embodiments and modifications can be implemented by appropriately combining them if possible.

  An internal combustion engine having a heater core (not shown) through which cooling water is circulated, and having an air conditioner that blows air heated in the heater core into a vehicle interior by a blower motor and supplies the air to the vehicle interior; When the drive of the water pump 56 is stopped, it is possible to prevent the blower motor from blowing air. When the driving of the water pump 56 is stopped, unlike the case where the water pump 56 is driven, there may be a temperature state that does not occur during normal engine operation, such as a local temperature rise in the heater core. When the heating performance is required and the same control is performed under such circumstances, there arises a problem that the heater core is excessively cooled. According to the present embodiment, it is possible to suppress the occurrence of such a problem.

  In the above embodiment, the engine control is permitted to be executed after the water pump 56 is driven. However, after the water pump 56 is driven, the cooling water temperature THW converges to a predetermined value and reaches a steady state. Execution of engine control may be prohibited until the shift.

  Even after the water pump 56 is driven, until the cooling water is circulated to some extent in the cooling water passage 53 and the cooling water temperature THW shifts to the equilibrium state, the degree is gradually reduced. The engine 1 is placed in a temperature environment different from that of normal operation. According to the present embodiment, the above-described engine control is prohibited until the cooling water circulates to some extent and the cooling water temperature THW shifts to the equilibrium state. For this reason, it is possible to more reliably suppress the control with low reliability or the control at an inappropriate time.

  In the above embodiment, an electric pump is used as the water pump 56, but an engine-driven pump may be adopted as the engine-driven pump. The engine driven pump is connected to the crankshaft via a clutch. When the clutch is connected, the engine-driven pump is driven by the power of the crankshaft, and when the clutch is disconnected, the operation of the engine-driven pump is stopped. Also in this embodiment, the effect according to the said effect can be show | played.

  In the above embodiment, the driving of the water pump 56 is stopped when the cooling water temperature THW is lower than the reference temperature TX. However, the driving of the water pump 56 may not be completely stopped, and the cooling water temperature THW is What is necessary is just to discharge with a discharge amount smaller than the discharge amount when the temperature is equal to or higher than the reference temperature TX.

  -Control which prohibits execution in the period which restrict | limits the distribution | circulation of cooling water is not restricted to the control quoted in the said embodiment. In an internal combustion engine in which the circulation of the cooling water is restricted and the temperature is different from a normal temperature, any control can be applied as long as the reliability is reduced.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 11 ... Cylinder block, 12 ... Cylinder head, 14 ... Oil pan, 21 ... Cylinder, 22 ... Combustion chamber, 23 ... Piston, 24 ... Crankshaft, 26 ... Fuel injection valve, 27 ... Spark plug, 30 DESCRIPTION OF SYMBOLS ... Intake passage, 31 ... Exhaust passage, 32 ... Intake valve, 33 ... Exhaust valve, 34 ... Intake camshaft, 35 ... Exhaust camshaft, 41 ... Exhaust purification catalyst, 50 ... Cooling device, 51 ... Radiator, 52 ... Water jacket 53 ... Cooling water passage, 53a ... Flow passage, 55 ... Detour passage, 56 ... Water pump (pump, control part), 57 ... Thermostat, 60 ... Throttle valve, 61 ... Motor, 63 ... Throttle body, 64 ... Restriction part 70 ... Variable valve timing mechanism, 71 ... Hydraulic circuit, 72 ... Advance side oil passage, 73 ... Delay side oil passage, 74 ... Oil control Control valve, 75 ... oil pump, 76 ... supply passage, 77 ... discharge passage, 91 ... electronic control device (control section, correction section, ignition timing learning section, reference opening learning section), 92 ... water temperature sensor (water temperature detection section) 94, cam angle sensor, 95, knock sensor, 96, throttle opening sensor, 97, air-fuel ratio sensor, 98, crank angle sensor, 99, accelerator sensor.

Claims (1)

An engine cooling system through which the cooling water flows, a water temperature detection unit for detecting the temperature of the cooling water, a pump capable of changing the discharge amount of the cooling water without depending on the engine operating state, and the cooling water temperature from a reference temperature In a control device for an internal combustion engine comprising a control unit that controls the discharge amount of the pump so that the flow of cooling water in the engine cooling system is restricted when compared to when it is high,
At least one of the engine controls is prohibited until the restriction on the circulation of the cooling water is released, and after the restriction on the circulation of the cooling water is released, the detected cooling water temperature converges to a predetermined value and is balanced. A control apparatus for an internal combustion engine, wherein the prohibition of the engine control is continued until the state is shifted.