JP2012136947A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine that can prevent a vane of a valve timing varying mechanism from colliding with a housing due to the effect of torque variation.SOLUTION: The internal combustion engine, which is controlled by an electronic control device 100 that is the control device for the internal combustion engine includes: an oil circulation system 400 for carrying out a low pressure control to reduce an amount of oil circulated to a demand part; and a hydraulic driven valve timing varying mechanism 200 for varying a valve timing using the pressure of supplied oil. The electronic control unit 100 carries out the low pressure control when the demand part has less demand for oil so that a driving load of an oil pump 40 acting on the internal combustion engine is reduced. The electronic control unit 100 monitors the magnitude of variation in torque of the internal combustion engine, and prohibits, when the torque variation is larger than a predetermined value, the low pressure control from being carried out.

Description

  The present invention relates to a control device for an internal combustion engine including an oil circulation system capable of executing low pressure control for reducing a driving load of an oil pump, and a hydraulically driven valve timing changing mechanism.

  Patent Document 1 discloses an internal combustion engine having an oil circulation system that can reduce the driving load of an oil pump and contribute to low fuel consumption by executing low pressure control for reducing the amount of circulation of oil supplied to a demand section. Is described.

  In such an oil circulation system, when the demand amount of oil is small, the oil circulation amount is limited, and the oil pump driving load is reduced by suppressing the oil pump from being driven unnecessarily. By reducing the driving load of the oil pump in this way, the amount of work of the oil pump can be adjusted according to the amount of oil required, so that the fuel consumption of the internal combustion engine can be suppressed. .

JP 2009-41445 A

  The internal combustion engine described in Patent Document 1 includes a hydraulically driven valve timing changing mechanism. In the hydraulically driven valve timing changing mechanism, the rotor fixed to the tip of the camshaft is housed in the housing formed integrally with the sprocket connected to the output shaft of the internal combustion engine via the timing chain. Has been. The rotor is provided with a plurality of vanes protruding in the radial direction, and the housing is provided with a storage chamber for storing the vanes. As a result, each storage chamber is partitioned into an advance hydraulic chamber and a retard hydraulic chamber via vanes.

  In the internal combustion engine having the valve timing changing mechanism configured as described above, the rotor is rotated in the housing by adjusting the hydraulic pressure in the advance hydraulic chamber and the retard hydraulic chamber, and the rotor with respect to the sprocket and Change the relative rotation phase of the camshaft. Thus, by changing the relative rotational phase of the camshaft to the advance side or the retard side, the valve timing of the intake valve or the exhaust valve is changed to an appropriate timing according to the engine operating state.

  By the way, since the valve timing changing mechanism is connected to the crankshaft via the timing chain, when the output torque of the internal combustion engine fluctuates, the torque fluctuation is also input to the valve timing changing mechanism via the timing chain. become. In other words, when torque fluctuation occurs, the torque fluctuation is transmitted to the housing connected to the crankshaft via the timing chain, so that the rotor is relatively rotated within the housing between the housing and the rotor. Forces to act will be applied.

  As described above, when the low pressure control for limiting the amount of oil circulation is executed, the hydraulic pressure supplied to each hydraulic chamber of the valve timing changing mechanism is also lowered, so that the rotor can easily rotate relatively in the housing. It has become. Therefore, when the low pressure control is being performed, the rotor may rotate greatly when torque fluctuation occurs, and the vane may collide with the housing.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for an internal combustion engine that can prevent the vane of the valve timing changing mechanism from colliding with the housing due to the influence of torque fluctuation. There is.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is an oil circulation system capable of executing low-pressure control for reducing the amount of oil circulation to the demand section, and a hydraulic drive that changes the valve timing using the oil pressure of the supplied oil. An internal combustion engine control device that reduces the drive load of an oil pump that acts on the internal combustion engine by executing the low pressure control when the demand for oil in the demand section is low. The gist of the invention is to monitor the magnitude of torque fluctuation of the engine and prohibit execution of the low pressure control when the torque fluctuation is larger than a reference value.

  According to the above configuration, when the fluctuation of the torque output from the internal combustion engine is large, that is, when the torque fluctuation is large, the low pressure control is prohibited, and the hydraulic pressure in each hydraulic chamber in the valve timing changing mechanism is compared with the case where the low pressure control is executed. Will be maintained higher. Therefore, the relative rotation of the rotor is suppressed by the hydraulic pressure in each hydraulic chamber, and the vane of the valve timing changing mechanism can be prevented from colliding with the housing due to the influence of torque fluctuation. As a result, it is possible to suppress the generation of noise due to the vane colliding with the housing and the deterioration of the durability of the valve timing changing mechanism.

  According to a second aspect of the present invention, in the control device for an internal combustion engine according to the first aspect, when the amount of change in the engine rotational speed per unit time is larger than the reference amount of change, the torque fluctuation is greater than the reference value. The gist is to determine that the value is larger.

  When torque fluctuation occurs, the engine rotation speed, which is the rotation speed of the crankshaft of the internal combustion engine, changes. Therefore, in monitoring the magnitude of torque fluctuation, when the amount of change in engine rotation speed per unit time is larger than the reference amount of change as described in claim 2, the torque fluctuation is the reference. It is desirable to adopt a configuration for determining that the value is larger than the value. By adopting such a configuration, it is possible to easily determine that the torque fluctuation is larger than the reference value by monitoring the amount of change in the engine rotation speed.

  The amount of change in engine speed per unit time can be estimated based on the rate of change in engine speed per unit time or the difference in engine speed per unit time. Therefore, a configuration for determining that the torque fluctuation is large when the rate of change in engine speed per unit time is larger than a reference value, and the difference in engine speed per unit time is larger than a reference value. Sometimes, it is possible to adopt a configuration for determining that the torque fluctuation is larger than the reference value.

The invention according to claim 3 is the control apparatus for an internal combustion engine according to claim 2, wherein the reference change amount is decreased as the temperature of the oil is higher.
The higher the temperature of the oil, the lower the viscosity of the oil and the easier the rotor rotates relative to the influence of torque fluctuation. On the other hand, as in the invention described in claim 3, the threshold value is a threshold value of the amount of change in engine speed when determining that the torque fluctuation is larger than the reference value as the oil temperature is higher. If the configuration in which the “reference change amount” in Item 2 is reduced is adopted, the lower the torque fluctuation, the lower the low-pressure control, as the oil temperature is higher and the rotor is more likely to rotate relatively. . Therefore, even when the viscosity of the oil is low and the rotor is easily rotated relatively due to the influence of torque fluctuation, it is possible to suitably suppress the vane from colliding with the housing.

The invention according to claim 4 is the control device for the internal combustion engine according to claim 3, wherein the temperature of the oil is estimated based on the engine coolant temperature.
The temperature of the oil circulating through each part of the internal combustion engine increases as the engine temperature increases. On the other hand, since the engine coolant temperature has a high correlation with the engine temperature, the oil temperature can be estimated based on the engine coolant temperature.

  Since the engine coolant temperature is widely used as an index for estimating the engine temperature, many internal combustion engines are provided with a water temperature sensor. Therefore, if the configuration for estimating the oil temperature based on the engine cooling water temperature as described in claim 4 is employed, the oil temperature is estimated based on the engine cooling water temperature detected by the water temperature sensor. Thus, the oil temperature can be estimated without newly providing an oil temperature sensor for detecting the oil temperature.

The invention according to claim 5 is the control device for the internal combustion engine according to claim 4, wherein the lower the engine coolant temperature, the lower the oil temperature is determined.
As the engine coolant temperature is lower, the engine temperature is estimated to be lower, so the temperature of the oil circulating inside the internal combustion engine is also expected to be lower. Therefore, in estimating the oil temperature based on the engine cooling water temperature, it is desirable to employ a configuration in which it is estimated that the lower the engine cooling water temperature, the lower the oil temperature, as described in claim 5. .

  In addition to the engine coolant temperature, as a value for estimating the amount of heat generated by combustion in the internal combustion engine, the integrated value of the fuel injection amount, the integrated value of the intake air amount, etc. are referred to, and the oil temperature is determined based on these values. It is also possible to adopt a configuration that estimates

The schematic diagram which shows the relationship between the electronic control apparatus which concerns on one Embodiment of this invention, the valve timing change mechanism which is the control object, and an oil circulation system. The schematic diagram which shows the operation | movement aspect in the high relief pressure state of the oil circulation system which concerns on the embodiment. The schematic diagram which shows the operation | movement aspect in the low relief pressure state of the oil circulation system which concerns on the embodiment. The map which shows the execution area | region of low voltage | pressure control. The flowchart which shows the flow of the process of the routine which determines whether low pressure control is prohibited.

Hereinafter, an embodiment in which a control device for an internal combustion engine according to the present invention is embodied as an electronic control device 100 that comprehensively controls the internal combustion engine will be described with reference to FIGS.
As shown in the upper part of FIG. 1, a valve timing changing mechanism 200 is attached to the camshaft 12 of the internal combustion engine. A timing chain wound around the crankshaft is wound around the sprocket 21 formed on the outer peripheral portion of the valve timing changing mechanism 200. As a result, when the crankshaft rotates during engine operation, the driving force is transmitted to the valve timing changing mechanism 200 via the timing chain, and the camshaft 12 rotates together with the valve timing changing mechanism 200.

  As shown in FIG. 1, a rotor 23 fixed to the camshaft 12 is rotatably accommodated in a housing 22 formed integrally with the sprocket 21. The rotor 23 is provided with four vanes 24 projecting radially outward, and the housing 22 is provided with four accommodating chambers 25 for accommodating the vanes 24, respectively.

  Thus, as shown in FIG. 1, the storage chamber 25 is divided into an advance hydraulic chamber 26 and a retard hydraulic chamber 27 by the vane 24 in a state where the rotor 23 is stored in the housing 22.

  By adjusting the hydraulic pressure in the advance hydraulic chamber 26 and the retard hydraulic chamber 27 formed so as to sandwich the vane 24 in this way, the vane 24 moves in the accommodation chamber 25 and the rotor 23 moves to the housing 22. Relative rotation.

  The amount of oil supplied to the advance hydraulic chamber 26 and the retard hydraulic chamber 27 is controlled by an oil control valve 300 shown in the center of FIG. The oil introduced into the valve timing changing mechanism 200 via the oil control valve 300 is supplied via an oil circulation system 400 shown in the lower part of FIG.

  As shown in the lower part of FIG. 1, a supply passage 41 is connected to the oil pump 40 of the oil circulation system 400. The oil pump 40 is connected to the crankshaft of the internal combustion engine and is driven as the engine is operated.

  The oil circulation system 400 pumps up the oil stored in the oil pan 42 by the oil pump 40 and supplies it to the demand section of each part of the engine through the supply passage 41. In addition, the oil supplied to each part of the internal combustion engine and used for lubrication or the like is stored in the oil pan 42 attached to the lower part of the internal combustion engine after flowing down the internal combustion engine.

  As shown in FIG. 1, a relief valve 50 is provided in a portion of the supply passage 41 on the downstream side of the oil pump 40. The relief valve 50 is connected to a reflux passage 43 connected to a portion of the supply passage 41 upstream of the oil pump 40.

  As a result, when the hydraulic pressure in the supply passage 41 becomes equal to or higher than the relief pressure that is the pressure at which the relief valve 50 opens, the relief valve 50 is opened, and a part of the oil in the supply passage 41 is recirculated. The feed passage 41 is recirculated to the upstream side of the oil pump 40 in the supply passage 41.

  As will be described later, the relief valve 50 is configured to change the relief pressure in two stages by controlling the hydraulic pressure switching valve 60. The hydraulic pressure switching valve 60 is driven based on a drive command from the electronic control device 100.

  The electronic control unit 100 is also connected to the oil control valve 300, and supplies oil to the advance hydraulic chamber 26 and the retard hydraulic chamber 27 by controlling the oil control valve 300 as described above. Control the amount.

  As shown in the center of FIG. 1, an advance passage 44 is connected to the advance hydraulic chamber 26 of the valve timing changing mechanism 200, and a retard passage 45 is connected to the retard hydraulic chamber 27. ing. The advance passage 44 and the retard passage 45 are connected to the supply passage 41 and the discharge passage 46 via the oil control valve 300. For convenience of explanation, FIG. 1 illustrates a state in which the advance passage 44 and the retard passage 45 are connected to only one of the four storage chambers 25. In practice, however, an advance passage 44 is connected to the advance hydraulic chamber 26 of each storage chamber 25, and a retard passage 45 is connected to the retard hydraulic chamber 27 of each storage chamber 25. Each is connected.

  The oil pumped up from the oil pan 42 by the oil pump 40 is selectively supplied to the hydraulic chambers 26 and 27 through the supply passage 41. Further, the oil discharged from the hydraulic chambers 26 and 27 as the rotor 23 rotates is returned to the oil pan 42 through the discharge passage 46.

  The oil control valve 300 is a solenoid valve that is driven based on an electrical drive signal, and the supply passage 41, the discharge passage 46, the advance passage 44, and the retard passage 45 according to the duty ratio of the drive signal. Switch the connection mode.

  For example, when the duty ratio is 50%, the oil control valve 300 is in a state of blocking all the communication of the passages 41, 44, 45, and 46 as shown in FIG. When the duty ratio is larger than 50%, the supply passage 41 and the advance passage 44 are communicated with each other, and the discharge passage 46 and the retard passage 45 are communicated, and the advance angle is increased as the duty ratio is increased. The amount of oil supplied to the hydraulic chamber 26 is increased. On the other hand, when the duty ratio is smaller than 50%, the supply passage 41 and the retard passage 45 are communicated with each other, and the discharge passage 46 and the advance passage 44 are communicated with each other. The amount of oil supplied to the hydraulic chamber 27 is increased.

  Thus, when the duty ratio is larger than 50%, the oil pumped up by the oil pump 40 is supplied to the advance hydraulic chamber 26 through the supply passage 41 and the advance passage 44, and the retard hydraulic chamber. 27 is returned to the oil pan 42 through the retard passage 45 and the discharge passage 46. When the hydraulic pressure in the advance hydraulic chamber 26 increases in this manner, the rotor 23 rotates in the housing 22 clockwise in FIG. Along with this, the camshaft 12 rotates to the advance side, and the relative rotation phase of the camshaft 12 with respect to the crankshaft is displaced in a direction to advance the valve timing.

  On the other hand, when the duty ratio is smaller than 50%, the oil pumped up by the oil pump 40 is supplied to the retarding hydraulic chamber 27 through the supply passage 41 and the retarding passage 45, and the advance hydraulic chamber. The oil in 26 is returned to the oil pan 42 through the advance passage 44 and the discharge passage 46. When the hydraulic pressure in the retarding hydraulic chamber 27 increases in this way, the rotor 23 rotates counterclockwise in FIG. Along with this, the camshaft 12 rotates to the retard angle side, and the relative rotation phase of the camshaft 12 with respect to the crankshaft is displaced in a direction to retard the valve timing.

  When the duty ratio is set to 50%, the passages 41, 44, 45, and 46 are all blocked as described above, and the supply and discharge of oil in the hydraulic chambers 26 and 27 is stopped. Therefore, the rotation of the rotor 23 in the housing 22 is restricted by the hydraulic pressure in each of the hydraulic chambers 26 and 27, and the valve timing is maintained.

  The change of the valve timing by the valve timing changing mechanism 200 is executed by the electronic control device 100. The electronic control unit 100 includes a crank angle sensor 101 for detecting the rotation angle CA of the crankshaft of the internal combustion engine and an engine rotation speed NE that is the rotation speed of the crankshaft, and a cam position sensor for detecting the rotation angle CAMA of the camshaft 12. 102 is connected. A water temperature sensor 103 for detecting the engine cooling water temperature THW, an air flow meter 104 for detecting the intake air amount GA of the internal combustion engine, an accelerator position sensor 105 for detecting the accelerator operation amount ACCP by the driver, and the like are also connected. The electronic control unit 100 takes in signals output from these various sensors, executes various arithmetic processes, and controls each part of the engine based on the results.

  For example, the magnitude of the required output is estimated based on the accelerator operation amount ACCP, and the fuel injection amount Q of the internal combustion engine is controlled so as to generate an output commensurate with the required output magnitude. Further, the current relative rotation phase in the valve timing changing mechanism 200 is calculated based on the rotation angle CA of the crankshaft and the rotation angle CAMA of the camshaft 12. Then, a target phase is calculated based on the engine rotational speed NE and the intake air amount GA so as to achieve an optimal valve timing, and is output to the oil control valve 300 so that the actual relative rotational phase matches this target phase. Sets the duty ratio of the drive signal. By controlling the oil control valve 300 in this way, the amount of oil supplied to the advance hydraulic chamber 26 and the retard hydraulic chamber 27 is adjusted, and phase change control for changing the relative rotational phase of the crankshaft and the camshaft 12 is performed. By executing, the valve timing of the intake valve and the exhaust valve is changed to an appropriate timing according to the engine operating state.

Further, the electronic control unit 100 operates the hydraulic pressure switching valve 60 in order to control the hydraulic pressure and circulation amount of oil supplied to the demand part of the internal combustion engine through the supply passage 41.
Hereinafter, the configuration and operation of the relief valve 50 in the oil circulation system 400 according to the present embodiment will be described in detail with reference to FIGS. 2 and 3.

  As described above, the relief valve 50 is provided in the downstream portion of the supply passage 41 from the oil pump 40. As shown in FIG. 2, in the relief valve 50, a cylindrical sleeve 51 is accommodated in the housing so as to be slidable in the axial direction. A relief port 52 penetrating the sleeve 51 is formed on the radial side wall of the sleeve 51. Further, inside the sleeve 51, a bottomed cylindrical valve body 55 is accommodated so as to be slidable in the axial direction of the sleeve 51, that is, the vertical direction in FIG.

  A support member 57 is fixed on the bottom surface of the housing of the relief valve 50 in FIG. A compressed spring 56 is accommodated between the support member 57 and the valve body 55. As a result, the valve body 55 is always urged upward by the spring 56 in FIG. 2, that is, in the direction of closing the relief port 52.

  Therefore, in the relief valve 50, when the hydraulic pressure of the oil flowing through the supply passage 41 increases and the hydraulic pressure acting on the valve body 55 increases, the valve body 55 is biased by the spring 56 as indicated by an arrow. 2 is displaced downward in FIG. 2 so that the relief port 52 is opened.

  As shown on the right side of FIG. 2, the relief port 52 is formed so as to open into the reflux passage 43. Therefore, when the valve body 55 is displaced to the valve opening position, that is, the position where the relief port 52 is opened, the supply passage 41 and the return passage 43 are communicated with each other via the relief port 52.

  When the supply passage 41 and the reflux passage 43 are communicated with each other through the relief port 52 in this way, a part of the oil flowing through the supply passage 41 is returned to the upstream side of the oil pump 40 through the reflux passage 43. .

  In short, in the relief valve 50, the relief pressure is determined by the magnitude of the urging force of the spring 56. That is, the oil that flows through the supply passage 41 when the oil flowing through the supply passage 41 urges the valve body 55 downward in FIG. A part of the oil is returned to the upstream side of the oil pump 40.

  As shown in the lower part of FIG. 2, a back pressure chamber 58 is formed between the bottom surface 51 a of the sleeve 51 and the bottom surface of the housing to which the support member 57 is fixed. A part of the oil flowing through the supply passage 41 is guided to the back pressure chamber 58 through the branch passage 61 and the back pressure passage 62.

  As described above, the sleeve 51 is slidably supported in the axial direction in the housing of the relief valve 50. As a result, in the relief valve 50, due to the hydraulic pressure acting on the bottom surface 51a of the sleeve 51, the biasing force biasing the sleeve 51 upward in FIG. 2 and the hydraulic pressure acting on the top surface 51b. Thus, a force for urging the sleeve 51 downward is generated, and the sleeve 51 is displaced in the vertical direction within the housing according to the magnitude relationship.

  The shape of the sleeve 51 is designed so that the area of the bottom surface 51a where the hydraulic pressure in the back pressure chamber 58 acts is larger than the area of the top surface 51b where the hydraulic pressure of the oil flowing through the supply passage 41 acts. Yes. Therefore, when the back pressure chamber 58 is communicated with the supply passage 41 through the branch passage 61 and the back pressure passage 62 and the same hydraulic pressure is applied to the bottom surface 51a and the top surface 51b of the sleeve 51, the pressure receiving area of the bottom surface 51a is reduced. The force for urging the sleeve 51 upward is increased by an amount larger than the pressure receiving area of the top surface 51b. As a result, the sleeve 51 is displaced upward, and is positioned upward in the housing as shown in FIG.

  As shown on the left side of FIG. 2, a hydraulic pressure switching valve 60 is provided between the branch passage 61 connected to the supply passage 41 and the back pressure passage 62 connected to the back pressure chamber 58. A drain passage 63 is further connected to the hydraulic pressure switching valve 60. The hydraulic pressure switching valve 60 is connected to the branch passage 61 and the back pressure passage 62 as shown in FIG. As described above, the state in which the back pressure passage 62 and the drain passage 63 communicate with each other can be switched.

  The drain passage 63 is connected to a portion upstream of the oil pump 40 in the supply passage 41, and the back pressure is changed when the hydraulic pressure switching valve 60 is switched to a state in which the back pressure passage 62 and the drain passage 63 are communicated with each other. The oil in the chamber 58 is returned to the upstream side of the oil pump 40 in the supply passage 41.

  In the oil circulation system 400 of the present embodiment, the relief pressure is changed by controlling the oil pressure in the back pressure chamber 58 by operating the oil pressure switching valve 60 and changing the position of the sleeve 51 in the housing. To do.

  Specifically, as shown in FIG. 3, the hydraulic pressure switching valve 60 is operated so that the branch passage 61 and the back pressure passage 62 communicate with each other, and a part of the oil in the supply passage 41 is introduced into the back pressure chamber 58. In this case, a hydraulic pressure equal to the hydraulic pressure of the oil in the supply passage 41 acts on the bottom surface 51a of the sleeve 51. As a result, the force that urges the sleeve 51 upward in FIG. 3 due to the hydraulic pressure acting on the bottom surface 51a of the sleeve 51 causes the sleeve 51 to move toward the top surface 51b of the sleeve 51 in FIG. The force is greater than the downward biasing force, and the sleeve 51 is displaced upward to be positioned upward as shown in FIG.

  On the other hand, when the hydraulic pressure switching valve 60 is operated so as to connect the back pressure passage 62 and the drain passage 63 as shown in FIG. 2, the oil in the back pressure chamber 58 passes through the drain passage 63 and the supply passage 41. Is returned to the upstream side of the oil pump 40, and the hydraulic pressure in the back pressure chamber 58 decreases. As a result, the force that urges the sleeve 51 downward in FIG. 2 due to the oil pressure acting on the top surface 51b of the sleeve 51 causes the sleeve 51 to move toward the bottom surface 51a of the sleeve 51 due to the oil pressure acting on the bottom surface 51a of FIG. The force is greater than the force urging upward, and the sleeve 51 is displaced downward to be positioned downward as shown in FIG.

  In this way, when the sleeve 51 is positioned downward in the housing, the valve body 55 is displaced to the valve opening position as compared with the case where the sleeve 51 is positioned upward as shown in FIG. The amount of compression of the spring 56 increases. That is, at this time, the urging force received by the valve body 55 from the spring 56 is larger than when the sleeve 51 is positioned above, and the oil pressure in the supply passage 41 when the relief port 52 opens, That is, the relief pressure increases.

  On the other hand, as shown in FIG. 3, when the sleeve 51 is positioned in the upper portion in the housing, the valve body 55 is displaced to the valve opening position as compared with the case where the sleeve 51 is positioned below. The amount of compression of the spring 56 is reduced. That is, at this time, the urging force received by the valve body 55 from the spring 56 is smaller than when the sleeve 51 is positioned below, and the relief pressure is lowered.

  Thus, according to the oil circulation system 400 of the present embodiment, the hydraulic pressure in the back pressure chamber 58 can be controlled by operating the hydraulic pressure switching valve 60. As a result, the sleeve 51 is displaced in the expansion / contraction direction of the spring 56 to increase the relief pressure (the state shown in FIG. 2) and the low relief pressure state (the state shown in FIG. 3) where the relief pressure becomes low. ) And can be switched.

  The electronic control device 100 of the present embodiment estimates the magnitude of oil demand in the internal combustion engine based on the engine coolant temperature THW, the fuel injection amount Q, and the engine rotational speed NE, and when the demand for oil is not so large, Low pressure control for switching to a low relief pressure state by operating the hydraulic pressure switching valve 60 is executed.

  Specifically, the low pressure control is executed with reference to a control switching map as shown in FIG. In this control switching map, the engine operating speed NE and the fuel injection amount Q are parameters, and the operation region is divided into two with the boundary line L as a boundary. As shown in FIG. 4, the two operation areas divided by the boundary line L are set to a low pressure control area in which the low rotational speed side and the low injection amount side of the boundary line L execute the low pressure control. On the other hand, the region on the higher rotational speed side and the higher injection amount side than the boundary line L is a high pressure control region in which the low pressure control is not executed.

  The boundary line L is displaced according to the engine coolant temperature THW. Specifically, as indicated by an arrow in FIG. 4, the lower the engine cooling water temperature THW, the wider the low pressure control region, while the higher the engine cooling water temperature THW, the smaller the low pressure control region. For example, when the engine coolant temperature THW is low, the boundary line L is displaced from the position indicated by the solid line to the position indicated by the broken line L1. When the engine coolant temperature THW is lower than that, the boundary line L is displaced to the position indicated by the broken line L2.

  The electronic control unit 100 refers to this switching map, and the current operation state belongs to the low pressure control region or the high pressure control region based on the engine coolant temperature THW, the fuel injection amount Q, and the engine rotational speed NE at that time. It is determined whether. Then, when belonging to the low pressure control region, the low pressure control for switching to the low relief pressure state is performed by operating the hydraulic pressure switching valve 60.

  Note that the low pressure control is executed when the engine speed NE is low or the fuel injection amount Q is small when the low pressure control region belongs to the low rotation speed side and the low injection amount side low pressure control region. This is because the amount of oil required for lubrication can be reduced. That is, when belonging to the low pressure control region, it is estimated that the demand for oil is not so great because the movement speed of the piston and crankshaft is low and the combustion heat generated in the combustion chamber is also small. Therefore, the electronic control device 100 according to the present embodiment determines that the demand for oil is not so large based on belonging to the low pressure control region, and executes the low pressure control.

  In this way, when the demand for oil is small, switching to the low relief pressure state and executing low pressure control to reduce the oil pressure of the oil flowing in the supply passage 41 will limit the amount of oil circulation and act on the internal combustion engine. The drive load of the oil pump 40 can be reduced and the fuel consumption of the internal combustion engine can be suppressed. That is, the amount of oil circulation is limited in accordance with the required amount, and excessive driving of the oil pump 40 caused by pumping oil more than necessary is suppressed, thereby saving fuel.

  Further, when the internal combustion engine is not warmed up, the low pressure control is performed when the engine is cold, so that the circulation amount of oil used for cooling each part of the engine is reduced, and the temperature of each part of the engine becomes the combustion of the internal combustion engine. It will rise quickly due to heat, and warm-up can be completed early.

  By the way, since the valve timing changing mechanism 200 is connected to the crankshaft via the timing chain, when the output torque of the internal combustion engine fluctuates, the torque fluctuation is also input to the valve timing changing mechanism 200 via the timing chain. Become so. That is, when torque fluctuation occurs, the torque fluctuation is transmitted to the housing 22 of the valve timing changing mechanism 200 connected to the crankshaft via the timing chain. Therefore, a force that relatively rotates the rotor 23 in the housing 22 acts.

  As described above, when the low pressure control for limiting the amount of oil circulation is being performed, the hydraulic pressure supplied to the hydraulic chambers 26 and 27 of the valve timing changing mechanism 200 is also reduced, and therefore the rotor 23 within the housing 22 is reduced. Are easy to rotate relative to each other. Therefore, when the low pressure control is being executed, the rotor 23 may rotate greatly when torque fluctuation occurs, and the vane 24 may collide with the housing 22.

Therefore, in the electronic control apparatus 100 of the present embodiment, the torque fluctuation of the internal combustion engine is monitored, and when the torque fluctuation is large, execution of the low pressure control is prohibited.
Hereinafter, the flow of the routine processing for determining whether or not to prohibit the execution of the low pressure control will be described with reference to the flowchart of FIG. This routine is repeatedly executed at a predetermined control cycle by the electronic control unit 100 during engine operation.

  When this routine is started, the electronic control unit 100 first determines in step S100 whether or not the torque fluctuation is larger than a reference value. Here, it is determined whether or not the magnitude of the torque fluctuation is larger than the reference value by monitoring the change in the engine speed NE.

  Specifically, the amount of change in the engine rotational speed NE per unit time is calculated, and it is determined that the magnitude of torque fluctuation is larger than the reference value when the calculated amount of change is larger than the reference amount of change. To do. Here, the change rate of the engine rotation speed NE per unit time is calculated, and the change amount of the engine rotation speed NE per unit time is estimated based on the calculated change rate.

  The reference change amount is set corresponding to the magnitude of the reference value, and the reference value is such that the vane 24 does not collide with the housing 22 even when the low pressure control is being executed. Is set based on the magnitude of torque fluctuation. In other words, if the magnitude of torque fluctuation is less than the reference value, the reference value is large so as to ensure that the vane 24 does not collide with the housing 22 even when the low pressure control is executed. Is set.

  When it is determined in step S100 that the torque fluctuation is larger than the reference value (step S100: YES), the process proceeds to step S300, and the electronic control unit 100 prohibits execution of the low pressure control. That is, when it is determined that the torque fluctuation is larger than the reference value, it is determined by referring to the switching map shown in FIG. 4 that the current operating state belongs to the low pressure control region. Even in this case, the high relief pressure state is maintained without performing the low pressure control.

  On the other hand, if it is determined in step S100 that the torque fluctuation is equal to or less than the reference value (step S100: NO), the process proceeds to step S200, and the electronic control unit 100 switches the switching shown in FIG. 4 as described above. Perform normal control with reference to the map.

  As described above, in the electronic control apparatus 100 according to the present embodiment, by repeatedly executing the routine shown in FIG. 5 during engine operation, execution of the low pressure control is prohibited when the torque fluctuation is larger than the reference value. I am doing so.

Next, the operation of the electronic control device 100 configured as described above will be described.
When the torque fluctuation of the internal combustion engine is larger than the reference value, execution of the low pressure control is prohibited. Therefore, when the torque fluctuation is larger than the reference value, the hydraulic pressure in each of the hydraulic chambers 26 and 27 in the valve timing changing mechanism 200 is maintained higher than when the low pressure control is executed.

Thereby, according to said embodiment, the following effects come to be acquired.
(1) The relative rotation of the rotor 23 is suppressed by the hydraulic pressure in each of the hydraulic chambers 26 and 27 maintained higher than when low-pressure control is executed, and the vane of the valve timing changing mechanism 200 is affected by the torque fluctuation. It can suppress that 24 collides with the housing 22. FIG. Therefore, it is possible to suppress the generation of noise due to the vane 24 colliding with the housing 22 and the deterioration of the durability of the valve timing changing mechanism 200.

  (2) When torque fluctuation occurs, the engine rotational speed NE, which is the rotational speed of the crankshaft of the internal combustion engine, changes. On the other hand, in the above-described embodiment, a configuration is adopted in which it is determined that the torque fluctuation is larger than the reference value when the change amount of the engine speed NE per unit time is larger than the reference change amount. is doing. Therefore, it is possible to easily determine that the torque fluctuation is larger than the reference value by monitoring the change amount of the engine rotational speed NE.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, the configuration in which the amount of change in the engine speed NE per unit time is estimated based on the rate of change in the engine speed NE per unit time has been shown, but the engine speed NE per unit time has been shown. Can be estimated based on the difference in engine speed NE per unit time. Therefore, it is possible to adopt a configuration in which it is determined that the torque fluctuation is larger than the reference value when the difference in the engine speed NE per unit time is larger than the reference value.

  -The higher the temperature of the oil, the lower the viscosity of the oil, and the relative rotation of the rotor 23 becomes easier due to the influence of torque fluctuation. Therefore, if a configuration is adopted in which the “reference change amount” that is the threshold value of the change amount of the engine rotational speed NE when determining that the torque fluctuation is larger than the reference value as the oil temperature is higher, As the temperature of the oil is higher and the rotor 23 is more likely to rotate relatively, the low pressure control is prohibited from a state where the torque fluctuation is small. Therefore, in addition to the effects of the above (1) and (2), in addition to the structure of the above embodiment, if the structure in which the “reference change amount” is made smaller as the oil temperature is higher is adopted. The following effect (3) can be obtained.

  (3) Even when the viscosity of the oil is low and the rotor 23 is relatively easily rotated due to the influence of torque fluctuation, it is possible to suitably suppress the vane 24 from colliding with the housing 22. .

  -Moreover, the temperature of the oil which circulates through each part of an internal combustion engine becomes so high that an engine temperature is high. On the other hand, since the engine coolant temperature THW has a high correlation with the engine temperature, it is desirable to estimate the oil temperature based on the engine coolant temperature THW.

  Since the engine cooling water temperature THW is widely used as an index for estimating the engine temperature, a water temperature sensor 103 is provided in many internal combustion engines. Therefore, if a configuration for estimating the oil temperature based on the engine cooling water temperature THW is employed, the oil temperature is detected by estimating the oil temperature based on the engine cooling water temperature THW detected by the water temperature sensor 103. Therefore, the oil temperature can be estimated without newly providing an oil temperature sensor.

  -It is estimated that the lower the engine coolant temperature THW, the lower the engine temperature, so the temperature of oil circulating inside the internal combustion engine is also expected to be lower. Therefore, when estimating the oil temperature based on the engine coolant temperature THW, it is desirable to adopt a configuration in which it is estimated that the oil temperature is lower as the engine coolant temperature THW is lower.

  In addition to the engine coolant temperature THW, as a value for estimating the amount of heat generated by combustion in the internal combustion engine, refer to an integrated value of the fuel injection amount Q, an integrated value of the intake air amount GA, etc., and based on these values A configuration for estimating the temperature of the oil can also be employed.

-Of course, an oil temperature sensor that directly detects the temperature of the oil may be provided to directly detect the oil temperature.
In the above embodiment, the oil control valve 300 configured to increase the amount of oil supplied to the advance hydraulic chamber 26 as the duty ratio increases is shown. The invention is not limited to the one provided with the control valve 300.

  For example, as opposed to the above-described embodiment, the present invention is a control device that controls an inner edge engine including an oil control valve configured to increase the amount of oil supplied to the advance hydraulic chamber 26 as the duty ratio decreases. Can also be applied.

DESCRIPTION OF SYMBOLS 12 ... Camshaft, 21 ... Sprocket, 22 ... Housing, 23 ... Rotor, 24 ... Vane, 25 ... Storage chamber, 26 ... Advance angle hydraulic chamber, 27 ... Delay angle hydraulic chamber, 40 ... Oil pump, 41 ... Supply Passage, 42 ... oil pan, 43 ... reflux passage, 44 ... advance angle passage, 45 ... retard angle passage, 46 ... discharge passage, 50 ... relief valve, 51 ... sleeve, 51a ... bottom surface, 51b ... top surface, 52 ... Relief port, 55 ... Valve, 56 ... Spring, 57 ... Support member, 58 ... Back pressure chamber, 60 ... Hydraulic switching valve, 61 ... Branch passage, 62 ... Back pressure passage, 63 ... Drain passage, 100 ... Electronic control Device: 101 ... Crank angle sensor, 102 ... Cam position sensor, 103 ... Water temperature sensor, 104 ... Air flow meter, 105 ... Accelerator position sensor, 200 ... Valve timing Further mechanism, 300 ... oil control valve, 400 ... oil circulation system.

Claims (5)

An oil circulation system that can perform low-pressure control that reduces the amount of oil circulating to the demand section, and a hydraulically driven valve timing changing mechanism that changes the valve timing using the oil pressure of the supplied oil In the control device for an internal combustion engine that reduces the driving load of the oil pump that acts on the internal combustion engine by executing the low pressure control when the demand for oil in the demand section is low,
A control device for an internal combustion engine characterized by monitoring the magnitude of torque fluctuation of the internal combustion engine and prohibiting execution of the low pressure control when the torque fluctuation is larger than a reference value. The control apparatus for an internal combustion engine according to claim 1,
A control device for an internal combustion engine, characterized in that when the amount of change in engine speed per unit time is larger than a reference amount of change, it is determined that the torque fluctuation is larger than a reference value. The control device for an internal combustion engine according to claim 2, wherein the reference change amount is decreased as the temperature of the oil is higher. The control device for an internal combustion engine according to claim 3, wherein the temperature of the oil is estimated based on the engine coolant temperature. The control device for an internal combustion engine according to claim 4, wherein the lower the engine coolant temperature, the lower the oil temperature is determined.

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