JP5007656B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine provided with a valve opening / closing timing adjusting mechanism for adjusting an opening / closing timing of an intake valve and / or an opening / closing timing of an exhaust valve.

As a control device for an internal combustion engine equipped with a valve opening / closing timing adjustment mechanism, a period during which both the intake valve and the exhaust valve of the internal combustion engine are closed during the exhaust stroke (hereinafter, this period is referred to as “negative valve over”). It is known to control the valve opening / closing timing adjustment mechanism so that a “lap period” is formed. Hereinafter, this control is referred to as “negative valve overlap period formation control”. A control device that executes this negative valve overlap period formation control is described in, for example, Patent Document 1 below.
JP 2001-355462 A

  During the negative valve overlap period, hot burned gas is trapped in the combustion chamber and compressed as the piston rises. By transferring heat from the burned gas to be compressed to the member constituting the combustion chamber, the temperature of the member (that is, the temperature of the cooling water of the internal combustion engine) can be increased.

  Therefore, for example, when the operation state of the internal combustion engine is a state where the operation speed is low and the load is small, it is conceivable to use the negative valve overlap period formation control. This is based on the fact that even when the operating state of the internal combustion engine is as described above, the coolant temperature can be increased and stable combustion can be achieved in the combustion chamber.

  From this point of view, the control device described in Patent Document 1 performs the negative valve overlap period formation control when the condition that “the operating speed of the internal combustion engine and the load of the internal combustion engine are both small” is satisfied. It is determined to execute. On the other hand, when the above condition is not satisfied, it is determined that the negative valve overlap period formation control is not executed. That is, in the above control device, the above condition is set so that the cooling water temperature is unlikely to decrease (the cooling water temperature is likely to rise) when the above condition is not satisfied.

  Now, let us consider a case where the temperature of the outside air is low when the operating state of the internal combustion engine does not satisfy the above conditions. Here, in the control device described in Patent Document 1, the outside air temperature is not taken into account in determining whether or not to execute the negative valve overlap period formation control. Therefore, in this case, the negative valve overlap period formation control is not executed.

  As a result, in such a case as described above, a situation can occur in which the cooling water temperature decreases (the cooling water temperature is difficult to increase). For this reason, for example, when there is a heater request from the driver, the coolant temperature changes to a temperature lower than a temperature for satisfying the heater request (hereinafter also referred to as “heater required temperature”). There is a problem that the required heater temperature cannot be reached quickly.

  Even if the outside air temperature is low, the negative valve overlap period formation control is executed in consideration of the outside air temperature in order to suppress the cooling water temperature drop and increase the cooling water temperature rise degree. It should be determined whether or not to do so.

  Accordingly, an object of the present invention is to provide a control device for an internal combustion engine that determines whether or not to execute the negative valve overlap period formation control in consideration of the outside air temperature.

  The control device according to the present invention is applied to an internal combustion engine provided with a valve opening / closing timing adjusting mechanism for adjusting an opening / closing timing of an intake valve of the internal combustion engine and / or an opening / closing timing of an exhaust valve of the internal combustion engine.

  A feature of the control device according to the present invention is that an outside air temperature obtaining unit that obtains the temperature of outside air, and whether or not to execute the negative valve overlap period formation control based on at least the outside air temperature, determine the negative air pressure. Execution means for executing the negative valve overlap period formation control when it is determined that the valve overlap period formation control is executed.

  Here, “the temperature of the outside air” means the temperature of the air surrounding the internal combustion engine.

  According to the above configuration, when the outside air temperature is low, it can be determined that the negative valve overlap period formation control is executed. Therefore, even when the outside air temperature is low, a decrease in the cooling water temperature can be suppressed, and the degree of increase in the cooling water temperature can be increased.

  For this reason, for example, even when the outside air temperature is low, when there is a heater request from the driver, the temperature can be changed to a temperature higher than the heater required temperature. Further, the cooling water temperature can be quickly reached the heater required temperature.

  Further, when the cooling water temperature decrease is suppressed by executing the negative valve overlap period formation control and the increase degree of the cooling water temperature is increased, for example, the combustion temperature is increased (that is, the load is increased, the ignition timing is increased). The output fluctuation of the internal combustion engine is small as compared with the case of adjustment by the above. Therefore, according to the said structure, the fall of cooling water temperature can be suppressed, and the raise degree of cooling water temperature can be enlarged, suppressing the deterioration of drivability.

  In the control device according to the present invention, for example, when the execution unit satisfies a predetermined condition not including a condition related to the outside air temperature, the negative valve overlap period is set as the negative valve overlap period formation control. First execution means for executing first control determined according to one pattern, and the negative valve overlap period forming control when the predetermined condition is not satisfied and the outside air temperature is lower than a first threshold value. And a second execution means for executing a second control for determining the negative valve overlap period according to the second pattern.

  According to this, even when the predetermined condition is not satisfied, when the outside air temperature is low, the second control can be executed to form a negative valve overlap period. Therefore, even with the above configuration, even when the outside air temperature is low, it is possible to suppress a decrease in the cooling water temperature and increase the degree of increase in the cooling water temperature.

  In this case, the second pattern of the second control may be the same as or different from the first pattern of the first control. Moreover, you may add to the execution conditions of the said 2nd control that there exists a heater request | requirement by a driver | operator and an accelerator operation amount is smaller than a predetermined operation amount. This is based on the fact that the negative valve overlap period formation control is less necessary when there is no heater request or when the accelerator operation amount is large.

  The control device according to the present invention further includes a cooling water temperature acquisition unit that acquires a temperature of the cooling water of the internal combustion engine, wherein the second execution unit does not satisfy the predetermined condition and the outside air temperature is Is preferably lower than the first threshold, and the second control is preferably executed when the coolant temperature is lower than the second threshold.

  Thereby, even if it is a case where external temperature is low, the cooling water temperature lower than a 2nd threshold value can be reached quickly to a 2nd threshold value. Moreover, according to the said structure, when cooling water temperature is more than a 2nd threshold value, execution of 2nd control can be prohibited. Therefore, the opportunity for the second control to be executed unnecessarily can be reduced. As a result, it is possible to suppress a decrease in fuel consumption due to the formation of the negative valve overlap period.

  Even in this case, it may be added to the execution condition of the second control that there is a heater request from the driver and that the accelerator operation amount is smaller than a predetermined operation amount.

  Further, in the control device according to the present invention, the second execution means is a case where the predetermined condition is not satisfied and the outside air temperature is lower than the first threshold value, and the cooling water temperature is the first temperature. It is more preferable that the second control is configured to execute the second control even when the temperature is equal to or greater than two threshold values and the cooling water temperature tends to decrease.

  According to this, the second control can be executed before the cooling water temperature that is equal to or higher than the second threshold and has a decreasing tendency becomes lower than the second threshold. Therefore, it is possible to suppress a decrease in the cooling water temperature that has been in a downward trend and to be a temperature lower than the second threshold value. Even in this case, it may be added to the execution condition of the second control that there is a heater request from the driver and that the accelerator operation amount is smaller than a predetermined operation amount.

  In the control device according to the present invention, for example, the execution means sets a range of parameter values representing an operating state of the internal combustion engine so that the outside air temperature is higher than the first temperature than when the outside air temperature is the first temperature. Determining means for determining to be larger when the temperature is lower than the second temperature, and configured to execute the negative valve overlap period formation control when the value of the parameter is within the range. May be.

  More specifically, the determining means determines the range as a first range when the outside air temperature is equal to or higher than a first threshold, and sets the range when the outside air temperature is lower than the first threshold. You may comprise so that it may determine in the 2nd range larger than 1 range.

  According to this, when the outside air temperature is low, the value range of the parameter indicating the operating state of the internal combustion engine (for executing the negative valve overlap period formation control) can be determined as the second range. Therefore, the chance that the value of the parameter is within the above range can be increased. As a result, even when the outside air temperature is low, the negative valve overlap period formation control can be executed, the decrease in the cooling water temperature can be suppressed, and the degree of increase in the cooling water temperature can be increased.

  In this case, it may be added to the determination condition of the second range that there is a heater request from the driver and that the accelerator operation amount is smaller than a predetermined operation amount.

  Further, the control device according to the present invention includes a cooling water temperature acquisition unit that acquires a temperature of the cooling water of the internal combustion engine, and the determination unit is a case where the outside air temperature is smaller than the first threshold value. It is preferable that the range is determined to be the second range when the cooling water temperature is smaller than a second threshold value.

  Accordingly, even when the outside air temperature is low, the coolant temperature lower than the second threshold can be quickly reached the second threshold. Moreover, when the cooling water temperature is equal to or higher than the second threshold, it is possible to prohibit the range from being determined as the second range. Therefore, this also makes it possible to reduce the chance that the negative valve overlap period is unnecessarily formed, and to suppress a reduction in fuel consumption.

  Even in this case, it may be added to the determination condition of the second range that there is a heater request from the driver and that the accelerator operation amount is smaller than a predetermined operation amount.

  Further, in the control device according to the present invention, the determination means is a case where the outside air temperature is lower than the first threshold value and the cooling water temperature is equal to or higher than the second threshold value, and the cooling water temperature. It is more preferable that the range is determined to be the second range even when is in a downward trend.

  According to this, the range may be determined as the second range before the cooling water temperature that is equal to or higher than the second threshold and has a downward trend becomes lower than the second threshold. Therefore, this also can suppress the cooling water temperature from becoming lower than the second threshold value. Even in this case, it may be added to the determination condition of the second range that there is a heater request from the driver and that the accelerator operation amount is smaller than a predetermined operation amount.

(First embodiment)
Hereinafter, a first embodiment of a control device for an internal combustion engine according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration of a system in which a control device according to a first embodiment of the present invention is applied to a spark ignition type multi-cylinder (four-cylinder) internal combustion engine 10. The internal combustion engine 10 includes a cylinder block unit 20 including a cylinder block, a cylinder block lower case, an oil pan, and the like. A cylinder head portion 30 is fixed on the cylinder block portion 20. In addition, the intake system 40 and the exhaust system 50 of the internal combustion engine 10 supply a gasoline mixture to the cylinder block unit 20 and discharge the exhaust gas from the cylinder block unit 20 to the outside.

  The cylinder block unit 20 includes a crankshaft 21, an oil pump 22, and the like. The crankshaft 21 is rotated by the reciprocating motion of the piston. The oil pump 22 is disposed at a predetermined position on the side surface of the crankcase, and engine oil stored in the crankcase is referred to as a variable intake timing device (hereinafter also referred to as “InVVT device”) 32 and variable. Pumping is performed toward an exhaust timing device (hereinafter also referred to as “ExVVT device”) 34 or the like.

  The cylinder head unit 30 includes an intake valve 31, an InVVT device 32, an exhaust valve 33, an ExVVT device 34, and the like. The valve opening / closing timing adjustment mechanism includes an InVVT device 32 and an ExVVT device 34.

  FIG. 2 is a diagram showing a schematic configuration of a valve operating system in the internal combustion engine 10. The InVVT device 32 and the ExVVT device 34 include an intake cam shaft 32a and an exhaust cam shaft 34a for driving the intake valve 31 and the exhaust valve 33, respectively, housing members 32b and 34b, and rotor members 32c and 34c.

  The rotor members 32c and 34c are arranged on one end side of the intake camshaft 32a and the exhaust camshaft 34a so as to be coaxial with and integrally rotatable with the intake camshaft 32a and the exhaust camshaft 34a, respectively. The rotor members 32c and 34c are accommodated in the housing members 32b and 34b so as to be coaxial with and relative to the housing members 32b and 34b, respectively.

  The housing members 32b and 34b and the crankshaft 21 are connected to each other so as to be integrally rotatable along the direction of the solid line arrow in FIG.

  Further, engine oil is supplied from the inside of the crankcase to the inside of the housing members 32b and 34b through the passage formed in the intake camshaft 32a and the exhaust camshaft 34a and the oil pump 22. ing. The supply and discharge of engine oil into the housing members 32b and 34b causes the rotor members 32c and 34c to move to the housing members 32b and 34b by arrows A (advanced side) and arrow B (shown by broken lines in FIG. They are designed to rotate relative to each other along the direction of the retard side. The relative phase angles of the rotor members 32c and 34c (that is, the intake cam shaft 32a and the exhaust cam shaft 34a) with respect to the housing members 32b and 34b are fixed at a predetermined relative phase angle. Thereby, the opening / closing timing of the intake valve 31 and the opening / closing timing of the exhaust valve 33 are adjusted. As described above, the internal combustion engine 10 includes the valve train configured as described above.

  Further, the cylinder head part 30 includes an injector 35. The injector 35 injects fuel (in this example, gasoline) into the intake port.

  The intake system 40 includes a throttle valve or the like that makes the opening cross-sectional area of the intake passage variable. The exhaust system 50 includes a catalyst or the like in the exhaust passage.

  On the other hand, this system includes a hot-wire air flow meter 61, an intake cam position sensor 62, an exhaust cam position sensor 63, a crank position sensor 64, a water temperature sensor 65, an accelerator opening sensor 66, and an outside air temperature sensor 67.

  The hot-wire air flow meter 61 detects the air flow rate (mass flow rate) per unit time of the intake air flowing through the intake pipe. In this example, the in-cylinder intake fresh air amount Mc is estimated based on the detected air flow rate and an operation speed NE described later.

  The intake cam position sensor 62 and the exhaust cam position sensor 63 are signals having one pulse every time the intake cam shaft 32a and the exhaust cam shaft 34a rotate 90 ° (that is, every time the crankshaft 21 rotates 180 °). G2 signal) is generated. Based on these signals, the actual opening / closing timing of the intake valve 31 and the actual opening / closing timing of the exhaust valve 33 are detected.

  The crank position sensor 64 detects the operating speed NE of the internal combustion engine 10. The water temperature sensor 65 detects the cooling water temperature THW of the internal combustion engine 10. The accelerator opening sensor 66 detects the operation amount of the accelerator pedal 81 operated by the driver. The outside air temperature sensor 67 detects the outside air temperature THA.

  The system further includes an ECU (electric control device) 71 composed of a CPU and the like. The ECU 71 is electrically connected to the sensors 61 to 67 and a heater switch 82 described later. The ECU 71 supplies signals from the sensors 61 to 67 and the heater switch 82 to the CPU, and sends drive signals to the oil pump 22, the InVVT device 32, the ExVVT device 34, the injector 35, and the like according to instructions from the CPU. To do.

  Further, this system includes a heater switch 82 in an air conditioner (not shown). The heater switch 82 is operated in response to a driver's heater request. When the heater switch 82 is operated to “On”, the ECU 71 sends a drive signal to a valve or the like constituting the cooling water flow path so that the cooling water is supplied to a heater core (not shown).

(Outline of control)
Next, an outline of control of the control device according to the first embodiment will be described.

  In this example, the InVVT device 32 and the ExVVT device 34 are controlled by the ECU 71 so that the actual opening / closing timings of the intake valve 31 and the exhaust valve 33 approach (match) the target values of the opening / closing timings of the intake valve 31 and the exhaust valve 33. Feedback controlled. The target values for the opening / closing timings of the intake valve 31 and the exhaust valve 33 are determined based on the operating speed NE and the in-cylinder intake fresh air amount Mc.

  FIG. 3 is a diagram showing a table that defines the relationship between the target value of the opening / closing timing of the intake valve 31 and the exhaust valve 33, the operating speed NE, and the in-cylinder intake fresh air amount Mc. In this example, in principle, the target value is determined based on the operating speed NE, the in-cylinder intake fresh air amount Mc, and this table. Hereinafter, this table is also referred to as “normal control table”.

  More specifically, when the operation speed NE and the in-cylinder intake fresh air amount Mc are smaller than the predetermined first speed NE1 and the predetermined first fresh air amount Mc1, respectively, the target value of the valve opening timing of the intake valve 31 Is determined at a time corresponding to inhalation top dead center. In this case, the target value of the closing timing of the exhaust valve 33 is determined to be a timing that is advanced by a predetermined interval at a crank angle with respect to the timing corresponding to the suction top dead center.

  Thus, a period in which both the intake valve 31 and the exhaust valve 33 are closed in the exhaust stroke (hereinafter referred to as “negative valve overlap period”) is formed. The hot burned gas is compressed over the negative valve overlap period, and heat is transferred from the burned gas to the members constituting the combustion chamber.

  Hereinafter, the control for instructing the InVVT device 32 and the ExVVT device 34 to form the negative valve overlap period is also referred to as “exhaust valve early closing control”. This exhaust valve early closing control corresponds to the negative valve overlap period formation control. In the normal control table, an area where NE <NE1 and Mc <Mc1 and indicated by fine dots is also referred to as an “exhaust valve early closing control area”.

  In the exhaust valve early closing control region, the target value of the closing timing of the exhaust valve 33 becomes a more advanced timing as the operating speed NE is smaller and the in-cylinder intake fresh air amount Mc is smaller. (That is, the crank angle interval between the valve opening timing of the intake valve 31 and the valve closing timing of the exhaust valve 33 is increased). Hereinafter, the exhaust valve early closing control executed when the operating speed NE and the in-cylinder intake fresh air amount Mc are within the exhaust valve early closing control region will be referred to as “normal exhaust valve early closing control”. .

  As described above, the exhaust valve early closing control is executed when the operating speed NE and the in-cylinder intake fresh air amount Mc are small, the temperature of the members constituting the combustion chamber ( That is, it is based on the fact that the cooling water temperature THW) can be increased. Accordingly, even when the operating speed NE and the in-cylinder intake fresh air amount Mc are small, for example, combustion in the combustion chamber can be stabilized.

  On the other hand, when the operating speed NE and the in-cylinder intake fresh air amount Mc are equal to or higher than the predetermined first speed NE1 and the predetermined first fresh air amount Mc1, respectively, the target value of the closing timing of the exhaust valve 33 is The timing is determined to be retarded from the target value of the valve opening timing of the intake valve 31. Thereby, a period in which both the intake valve 31 and the exhaust valve 33 are opened in the exhaust stroke and the intake stroke is formed. In this case, the target value of the opening / closing timing of the intake valve 31 and the exhaust valve 33 and the length of the period during which both the intake valve 31 and the exhaust valve 33 are open are the operating speed NE and the in-cylinder intake fresh air amount. It is adjusted according to Mc.

  This is because, when the operating speed NE and the in-cylinder intake fresh air amount Mc are large, it is not necessary to form the negative valve overlap period when the outside air temperature THA is a reference outside air temperature that is not a low outside air temperature. This is based on the fact that the cooling water temperature THW is likely to rise. That is, in this example, the predetermined first speed NE1 and the predetermined first fresh air amount Mc1 are the operating speed NE at which the cooling water temperature THW does not tend to decrease in the state where the outside air temperature THA is the reference outside air temperature. And the minimum value within the range of the in-cylinder intake fresh air amount Mc.

  By the way, when NE ≧ NE1 and Mc ≧ Mc1 (that is, when the operating speed NE and the in-cylinder intake fresh air amount Mc are outside the exhaust valve early closing control region), the outside air temperature THA is low. (Specifically, when the outside air temperature THA is lower than the reference outside air temperature). In this case, a situation may occur in which the cooling water temperature THW decreases (or the cooling water temperature THW hardly increases).

  For this reason, when there is a heater request from the driver, a situation may occur in which the coolant temperature THW, which is equal to or higher than the heater required temperature, changes to a temperature lower than the heater required temperature. Moreover, a situation may occur in which the coolant temperature THW lower than the heater required temperature cannot quickly reach the heater required temperature.

  In order to suppress the occurrence of such a situation, in this example, the operation speed NE and the in-cylinder intake fresh air amount Mc are outside the exhaust valve early closing control region, and the predetermined temperature such as the outside air temperature THA is low. When the condition is satisfied, the exhaust valve early closing control for forming the negative valve overlap period is executed separately from the “normal exhaust valve early closing control”. Hereinafter, the exhaust valve early closing control executed in this case is also referred to as “exhaust valve early closing control at low outside air temperature”. The above is the outline of the control of the control device according to the first embodiment.

(Exhaust valve early closing control at low outside temperature)
Next, the exhaust valve early closing control at the time of low outside air temperature will be described with reference to the flowchart shown in FIG.

  The CPU of the ECU 71 executes the routine process shown by the flowchart in FIG. 4 every time a predetermined time in the combustion cycle of the internal combustion engine 10 arrives. Therefore, when the predetermined execution time of the routine comes, the CPU starts the process from step 400 and proceeds to step 405 to determine whether or not the normal-time exhaust valve early closing control condition is satisfied.

  Here, the normal exhaust valve early closing control condition is that the operating speed NE and the in-cylinder intake fresh air amount Mc are within the exhaust valve early closing control region (that is, the operating state of the internal combustion engine 10 is NE < NE1 and Mc <Mc1). That is, the normal exhaust valve early closing control condition corresponds to a predetermined condition that does not include the condition related to the outside air temperature.

  Therefore, when the normal exhaust valve early closing control condition is satisfied, the CPU makes a “Yes” determination at step 405 to proceed to step 410 to execute the normal exhaust valve early closing control. Then, the CPU proceeds to step 495 to end the processing of this routine once.

  In this normal exhaust valve early closing control, according to the normal control table, the negative valve overlap period is longer as the operating speed NE is smaller and the in-cylinder intake fresh air amount Mc is smaller. Is done. The formation pattern of the negative valve overlap period corresponds to the first pattern, and the normal exhaust valve early closing control corresponds to the first control. Steps 405 and 410 correspond to a part of the first execution means.

  On the other hand, if the normal exhaust valve early closing control condition is not satisfied, the CPU makes a “No” determination at step 405 to proceed to step 415, where there is a heater request from the driver, and from the driver. It is determined whether or not there is an acceleration request.

  Here, “there is a heater request” means that the heater switch 82 is currently operated “On”. Further, “no acceleration request” means that the accelerator operation amount at the present time is a fresh air amount Mc2 (hereinafter referred to as “second fresh air amount Mc2”) larger than the predetermined first fresh air amount Mc1 by a predetermined amount. It means that it is smaller than the amount of accelerator operation corresponding to.

  If the condition described in step 415 is not satisfied, the CPU makes a “No” determination at step 415 to immediately proceed to step 495 to end the processing of this routine once. Accordingly, in this case, since “NE ≧ NE1 and Mc ≧ Mc1”, the InVVT device 32 and the ExVVT device 34 are controlled by the normal control table so that the negative valve overlap period is not formed.

  The reason why the exhaust valve early closing control is not executed in this way is based on the viewpoint that it is less necessary to increase the coolant temperature THW or suppress the decrease in the coolant temperature THW when there is no heater request. Further, even if there is a heater request, if there is an acceleration request, it is based on the viewpoint that there is a high possibility that the coolant temperature THW can be increased in the future.

  On the other hand, if the condition described in step 415 is satisfied, the CPU determines “Yes” in step 415 and proceeds to step 420 to determine whether or not the outside air temperature THA is a low outside air temperature. .

  Here, “the outside air temperature THA is a low outside air temperature” means that when the outside air temperature THA at the present time is the in-cylinder intake fresh air amount Mc is the second fresh air amount Mc2, the cooling water temperature THW decreases. It means that the temperature is lower than the lowest temperature (corresponding to the first threshold value) within the range of the outside air temperature THA that does not tend to be.

  If the condition described in step 420 is not satisfied, the CPU makes a “No” determination at step 420 to immediately proceed to step 495 to end the processing of this routine once. Therefore, also in this case, the InVVT device 32 and the ExVVT device 34 are controlled by the normal time control table so that the negative valve overlap period is not formed.

  On the other hand, if the condition described in step 420 is satisfied, the CPU determines “Yes” in step 420 and proceeds to step 425 to determine whether or not the coolant temperature THW is the low coolant temperature. judge.

  Here, “the cooling water temperature THW is a low cooling water temperature” means that the current cooling water temperature THW is lower than the heater required temperature (corresponding to the second threshold value).

  If the condition described in step 425 is satisfied, the CPU makes a “Yes” determination in step 425 to proceed to step 430 to execute the low outside air temperature exhaust valve early closing control. Then, the CPU proceeds to step 495 to end the processing of this routine once.

  In the low outside air temperature exhaust valve early closing control, the target value of the opening / closing timing of the intake valve 31 and the exhaust valve 33 is determined to be a constant value (a constant crank angle) without using the normal time control table. More specifically, in this example, the negative valve overlap period formed by the exhaust valve early closing control at low outside air temperature is the negative valve overlap period formed by the normal time control table. As described above, the period is longer than the longest period (that is, the negative valve overlap period when the operating speed NE and the in-cylinder intake fresh air amount Mc are the minimum values within the assumed operating state range). A target value is determined. The formation pattern of the negative valve overlap period corresponds to the second pattern, and the exhaust valve early closing control at the low outside air temperature corresponds to the second control.

  On the other hand, if the condition described in step 425 is not satisfied, the CPU makes a “No” determination at step 425 to proceed to step 435. This is based on the viewpoint that even when the outside air temperature THA is a low outside air temperature, if the cooling water temperature THW is equal to or higher than the heater required temperature, the necessity for increasing the cooling water temperature THW is small.

  The CPU that has proceeded to step 435 determines whether or not the rate of increase of the coolant temperature THW is smaller than zero. Here, “the rate of increase of the coolant temperature THW is less than zero” means that the coolant temperature THW at the present time (above the heater required temperature) is the coolant temperature when this routine is executed a predetermined number of times before the present time. It means lower than THW.

  If the condition described in step 435 is satisfied, the CPU makes a “Yes” determination in step 435 to proceed to step 430 to execute the low outside air temperature exhaust valve early closing control.

  Even when the coolant temperature THW is equal to or higher than the above-mentioned heater required temperature, the exhaust valve early closing control is executed in this way, if the coolant temperature THW tends to decrease, the coolant temperature THW is controlled. Based on the viewpoint that it is preferable to suppress the decrease. The situation in which the cooling water temperature THW tends to decrease in this way is likely to occur when the operating speed NE and the in-cylinder intake fresh air amount Mc decrease and continue to be small, and in particular, the lower the outside air temperature THA, the more The downward trend becomes prominent.

  On the other hand, if the condition described in step 435 is not satisfied, the CPU makes a “No” determination at step 435 to immediately proceed to step 495 to end the processing of this routine once. These steps 405, 420, 425, 430, and 435 correspond to a part of the second execution means.

  As described above, according to the first embodiment of the control apparatus for an internal combustion engine of the present invention, when the normal exhaust valve early closing control condition not including the condition related to the outside air temperature THA is satisfied, the normal exhaust Early valve closing control is executed. In the normal exhaust valve early closing control, the normal valve control table forms a longer negative valve overlap period as the operating speed NE and the in-cylinder intake fresh air amount Mc are smaller.

  On the other hand, if the normal exhaust valve early closing control condition is not satisfied, the outside air temperature THA is a low outside air temperature, and the cooling water temperature THW is a low cooling water temperature, the low outside air temperature The exhaust valve early closing control is executed. In this low outside air temperature exhaust valve early closing control, the negative valve overlap period (constant at the crank angle) is longer than the longest negative valve overlap period that can be formed in the normal exhaust valve early closing control. It is formed.

  Accordingly, when the cooling water temperature THW is lower than the heater required temperature, the degree of increase in the cooling water temperature THW can be increased even when the outside air temperature THA is low. Accordingly, in this case, the coolant temperature THW can be quickly reached the heater required temperature.

  In addition, when the normal exhaust valve early closing control condition is not satisfied and the outside air temperature THA is a low outside air temperature and the cooling water temperature THW is not the low cooling water temperature, in principle, The exhaust valve early closing control at the low outside air temperature is not executed. Thereby, the chance that the exhaust valve early closing control is executed unnecessarily can be reduced. Accordingly, it is possible to suppress a reduction in fuel consumption due to the formation of the negative valve overlap period.

  Here, even when the cooling water temperature THW is not the low cooling water temperature, when the cooling water temperature THW tends to decrease, the low outside air temperature exhaust valve early closing control is executed. Thereby, the fall of the cooling water temperature THW more than heater required temperature can be suppressed. Therefore, in this case, it is possible to suppress the cooling water temperature THW from changing to a temperature lower than the heater required temperature.

  The present invention is not limited to the first embodiment, and various modifications can be employed within the scope of the present invention. For example, in the first embodiment, as the exhaust valve early closing control at the low outside air temperature, the negative valve overlap period is formed to be constant at the crank angle. The valve overlap period may be variable.

  In this case, for example, every time the CPU proceeds to step 430, the negative valve overlap period is increased by a predetermined period within the step 430 (that is, the target valve closing timing of the exhaust valve 33). The negative valve overlap period may be formed so that the value becomes a more advanced timing by a predetermined crank angle. Further, in step 430, the target value of the closing timing of the exhaust valve 33 may be determined as a more advanced timing so that the negative valve overlap period becomes longer as the outside air temperature THA is lower. .

  Further, in the first embodiment, when the CPU proceeds to step 430, the negative valve overlap period is formed once. You may make it form a negative valve overlap period in multiple times over the predetermined period after the execution conditions of valve early closing control are satisfied.

  In this case, for example, the number of formations of the negative valve overlap period may be increased as the outside air temperature THA is lower. Further, the number of negative valve overlap periods formed may be a fixed number regardless of parameters such as the outside air temperature THA.

  In addition, in the first embodiment, the normal exhaust valve early closing control and the low outside temperature exhaust valve early closing control have different negative valve overlap period formation patterns. Instead, the same formation pattern may be used in both controls. In this case, for example, in both controls, a synchronization period may be formed so that the negative valve overlap period is a predetermined interval at the crank angle.

(Second Embodiment)
Next, a second embodiment of the control device for an internal combustion engine according to the present invention will be described. In the second embodiment, when a predetermined condition such as the outside air temperature THA being a low outside air temperature is satisfied, whether or not the negative valve overlap period is formed is compared with the normal time control table. The only difference from the first embodiment is that a determination is made using a table having a large exhaust valve early closing region (hereinafter, this table is referred to as a “low outside air temperature control table”).

  Hereinafter, differences of the second embodiment from the first embodiment will be described with reference to the flowchart shown in FIG. 5 corresponding to FIG. In FIG. 5, the same steps as those in FIG. 4 are denoted by the same step numbers, and detailed description thereof is omitted.

  When the predetermined execution time of the routine arrives, the CPU provided in the ECU 71 of the second embodiment starts the process from step 500 and executes the processes after step 415. If it is determined “No” in any of steps 415, 420, and 435, the CPU proceeds to step 505 and selects the same table as the normal control table (see FIG. 3).

  On the other hand, if “Yes” is determined in any of steps 415, 420, and 425, or if “No” is determined only in step 425 and “Yes” is determined in step 435, the CPU Proceeding to step 510, the low outside air temperature control table is selected.

  FIG. 6 is a view corresponding to FIG. 3 showing the low outside air temperature control table. In this low outside air temperature control table, a predetermined second speed NE2 in which the operation speed NE and the in-cylinder intake fresh air amount Mc are larger than the first speed NE1 and the second fresh air amount Mc2 in the first embodiment, Are smaller than each, the target value of the opening / closing timing of the intake valve 31 and the exhaust valve 33 is determined so as to form a negative valve overlap period, as in the normal control table described above.

  Here, in this example, the predetermined second speed NE2 is set to the minimum value within the range of the operating speed NE at which the cooling water temperature THW does not decrease when the outside air temperature THA is the lowest temperature assumed. Has been.

  In the low outside air temperature control table, the region where NE <NE2 and Mc <Mc2 is the exhaust valve early closing control region (see the portion indicated by fine dots in FIG. 6). Further, the exhaust valve early closing control region is formed such that the negative valve overlap period becomes longer as the operating speed NE and the in-cylinder intake fresh air amount Mc are smaller.

  In this example, the exhaust valve early closing control region in the normal time control table corresponds to the first range, and the exhaust valve early closing control region in the low outside air temperature control table corresponds to the second range. Also, these steps 420, 425, 435, 505, 510 correspond to a part of the determining means.

  The CPU that has selected one of the normal time control table and the low outside air temperature control table next proceeds to step 515 to determine whether or not the exhaust valve early closing control condition is satisfied. Here, the exhaust valve early closing control condition is satisfied when the operating speed NE and the in-cylinder intake fresh air amount Mc are within the exhaust valve early closing control region of the selected table.

  Therefore, when the normal time control table is selected, the CPU determines “Yes” in step 515 when the operating state of the internal combustion engine 10 is in a state where NE <NE1 and Mc <Mc1. After making the determination and proceeding to step 520 and executing the exhaust valve early closing control, the routine proceeds to step 595 where the processing of this routine is temporarily terminated.

  On the other hand, when the low outside air temperature control table is selected, when the operating state of the internal combustion engine 10 is NE <NE2 and Mc <Mc2, the CPU determines “Yes in step 515. And proceeds to step 520 to execute the exhaust valve early closing control. Thus, when the low outside air temperature control table is selected, the exhaust valve early closing region is larger than the normal control table.

  Therefore, even if the operating speed NE and the in-cylinder intake fresh air amount Mc are outside the exhaust valve early closing control region in the normal time control table, they are within the exhaust valve early closing control region in the low outside air temperature control table. If so, exhaust valve early closing control is executed. Therefore, similarly to the first embodiment, even when the outside air temperature THA is low, the decrease in the coolant temperature THW can be suppressed, and the degree of increase in the coolant temperature THW can be increased.

  On the other hand, if the exhaust valve early closing control condition is not satisfied, the CPU makes a “No” determination at step 515 to immediately proceed to step 595 to end the processing of this routine once. In this case, the InVVT device 32 and the ExVVT device 34 are controlled by the normal time control table or the low outside air temperature control table so that the negative valve overlap period is not formed.

  As described above, in the second embodiment of the control apparatus for an internal combustion engine according to the present invention, the normal time control table and the low outside air temperature control table are provided. When a predetermined condition such as the outside air temperature THA being a low outside air temperature is not satisfied, the normal time control table is selected from the two tables. On the other hand, when the predetermined condition is satisfied, the low outside air temperature control table is selected from the two tables. Then, based on the selected table, it is determined whether or not to execute the exhaust valve early closing control.

  Here, the exhaust valve early closing control region in the low outside air temperature control table is larger than that in the normal time control table. Accordingly, when the outside air temperature THA is a low outside air temperature, the exhaust valve early closing control is executed even when the operating state of the internal combustion engine 10 is outside the exhaust valve early closing control region in the normal time control table. Can be done. Thereby, according to the said 2nd Embodiment, there can exist an effect similar to the said 1st Embodiment.

  In the first embodiment, when the normal exhaust valve early closing control condition is not satisfied and the predetermined condition such as the outside air temperature THA being a low outside air temperature is satisfied, the operation speed NE is satisfied. Regardless of the size of the exhaust valve, the exhaust valve early closing control was executed.

  On the other hand, in the second embodiment, even when a predetermined condition such as the outside air temperature THA being a low outside air temperature is satisfied and the low outside air temperature control table is selected, the operation speed NE is When the speed is equal to or higher than the predetermined second speed NE, the exhaust valve early closing control is not executed. Therefore, as compared with the first embodiment, the chance that the exhaust valve early closing control is unnecessarily executed can be reduced. As a result, it is possible to suppress a reduction in fuel consumption due to the formation of the negative valve overlap period as compared with the first embodiment.

  The present invention is not limited to the second embodiment, and various modifications can be adopted within the scope of the present invention. For example, in the second embodiment, one table is selected from the two tables of the normal time control table and the low outside air temperature control table, but instead, the operating speed NE and the in-cylinder table are selected. Three or more tables that define the relationship between the intake fresh air amount Mc and the opening / closing timings of the intake valve 31 and the exhaust valve 33 may be provided, and one table may be selected from the three or more tables.

  In this case, for example, the three or more tables are configured such that the sizes of the exhaust valve early closing control areas of the tables are different from each other. The lower the outside air temperature THA, the larger the exhaust valve early closing control area. May be selected.

  In each of the above embodiments, the normal time control table (and the low outside air temperature control table) uses the operating speed NE and the in-cylinder intake fresh air amount Mc as arguments. Instead of this, a table in which the cooling water temperature THW is further added as an argument may be used.

  Further, in each of the above embodiments, when the cooling water temperature THW is not a low cooling water temperature, it is immediately determined whether or not the cooling water temperature THW is in a downward trend, but instead, Even if the cooling water temperature THW is not a low cooling water temperature, if the cooling water temperature THW is sufficiently higher than the heater required temperature, the exhaust valve early closing control is not performed without performing the above determination. You may do it.

  This is because when the cooling water temperature THW is sufficiently higher than the heater required temperature, the cooling water temperature THW is lower than the heater required temperature even when the cooling water temperature THW tends to decrease. hard. Therefore, in this case, it is based on the viewpoint that the necessity of executing the exhaust valve early closing control is small.

  In this case, for example, between step 425 and step 435 in the flowchart of FIG. 4 or FIG. 5, the cooling water temperature THW is higher than a temperature higher than the heater required temperature by a predetermined temperature (for example, 5 ° C.). You may insert the step which determines whether it is low newly. If “Yes” is determined in this step, the CPU immediately proceeds to step 495 (or proceeds immediately to step 505 to select the normal time control table), and if “No” is determined, step is performed. You may make it progress to 435.

  Further, in each of the above embodiments, assuming that the cooling water temperature THW in the determination in step 435 tends to decrease, the current cooling water temperature THW is higher than the cooling water temperature THW when the routine is executed a predetermined number of times before the current time. However, instead of this, a case where the time differential value of the current coolant temperature THW is a negative value may be used.

  In this case, as the time differential value, for example, a value obtained by dividing the value obtained by subtracting the coolant temperature THW at the time of the current routine execution from that at the time of the previous routine execution by the time corresponding to the routine execution interval may be used. Good.

  In each of the above embodiments, the routines for executing the exhaust valve early closing control are provided with steps 425 and 435, respectively. However, even if steps 435 or 425 and 435 are not provided. Good.

  In addition, in each of the above embodiments, the routine shown in FIG. 4 or FIG. 5 is used as a routine for executing the exhaust valve early closing control. Instead, the operating speed NE, in-cylinder A table that defines the relationship between the time differential values of the intake fresh air amount Mc, the outside air temperature THA, the cooling water temperature THW, and the cooling water temperature THW and the target values of the opening / closing timings of the intake valve 31 and the exhaust valve 33 is provided. It is also possible to use a routine that can obtain the same operation and effect as the routine shown in FIG. 4 or FIG.

  In this case, for example, the time differential values of the operation speed NE, the in-cylinder intake fresh air amount Mc, the outside air temperature THA, the cooling water temperature THW, and the cooling water temperature THW at the present time are respectively controlled to quickly close the exhaust valve in the table. If it is within the region, the exhaust valve early closing control may be executed. Further, the table is configured such that the target values of the opening / closing timings of the intake valve 31 and the exhaust valve 33 are determined so that the negative valve overlap period becomes longer as the outside air temperature THA and the cooling water temperature THW are lower. Also good.

1 is a schematic configuration diagram of an entire system in which a control device according to a first embodiment of the present invention is applied to an internal combustion engine. It is a schematic block diagram of the valve operating system of the internal combustion engine shown in FIG. A table that defines the relationship between the operating speed of the internal combustion engine and the in-cylinder intake fresh air amount and the target values of the opening / closing timings of the intake and exhaust valves, which is referred to by the CPU of the electric control device shown in FIG. FIG. It is the flowchart which showed the program for execution of the exhaust valve early closing control which is control for forming the negative valve overlap period which CPU of the electric control apparatus shown in FIG. 1 performs. It is the flowchart which showed the program for execution of the exhaust valve early closing control which CPU of the control apparatus which concerns on 2nd Embodiment of this invention performs. A table that defines the relationship between the operating speed of the internal combustion engine and the in-cylinder intake fresh air amount and the target values of the opening and closing timings of the intake and exhaust valves, which are referred to by the CPU of the control device according to the second embodiment of the present invention. It is the figure which showed the control table at the time of low external temperature.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 31 ... Intake valve, 32 ... InVVT apparatus, 33 ... Exhaust valve, 34 ... ExVVT apparatus, 65 ... Water temperature sensor, 67 ... Outside temperature sensor, 71 ... Electric control apparatus.

Claims (3)

Applied to an internal combustion engine having a valve opening / closing timing adjustment mechanism for adjusting an opening / closing timing of an intake valve of the internal combustion engine and / or an opening / closing timing of an exhaust valve of the internal combustion engine;
Outside temperature acquisition means for acquiring the temperature of outside air;
Negative valve over which controls the valve opening / closing timing adjustment mechanism so as to form a negative valve overlap period that is a period during which both the intake valve and the exhaust valve are closed based on at least the outside air temperature Determining whether to execute the lap period formation control, and executing means for executing the negative valve overlap period formation control when it is determined that the negative valve overlap period formation control is executed;
An internal combustion engine control device comprising :
The execution means includes
When the predetermined condition not including the condition related to the outside air temperature is satisfied, the negative valve overlap period is determined as the first pattern corresponding to the operating state of the internal combustion engine as the negative valve overlap period formation control. First execution means for executing the first control;
When the predetermined condition is not satisfied and the outside air temperature is lower than the first threshold, the negative valve overlap period is formed in the first pattern as the negative valve overlap period formation control. Second execution means for executing second control to determine the second pattern that is longer than the longest period to be obtained;
The control apparatus of the internal combustion engine provided with . A control device for an internal combustion engine according to claim 1 ,
Cooling water temperature acquisition means for acquiring the temperature of the cooling water of the internal combustion engine,
The second execution means includes
The second control is executed when the predetermined condition is not satisfied and the outside air temperature is lower than the first threshold and the cooling water temperature is lower than the second threshold. Control device for an internal combustion engine. The control apparatus for an internal combustion engine according to claim 2 ,
The second execution means includes
When the predetermined condition is not satisfied, the outside air temperature is lower than the first threshold value, and the cooling water temperature is equal to or higher than the second threshold value, and the cooling water temperature tends to decrease. The control apparatus for an internal combustion engine configured to execute the second control even in the case of.

Images