JP2010159685A - Control device of internal combustion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine which can control the generation of shock caused by the high advancing speed of VVT from a retarded position to a targeted advanced position. <P>SOLUTION: The control device of the internal combustion engine is mounted on a hybrid vehicle and is provided with an engine and a control means. The engine is provided with a variable valve timing mechanism. The control means control the number of rotations of the engine based on the number of rotations of the engine targeted value rising rate. The control means, when it shifts the valve timing from the retarded position to the targeted advanced position after the engine is started, adds a chevron rising rate to the number of rotations of the engine targeted value rising rate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine having a variable valve timing mechanism.

  Conventionally, a control device for an internal combustion engine having a variable valve timing mechanism (VVT: Variable Valve Timing) is known. For example, Patent Document 1 discloses a technique for switching VVT switching timing in a predetermined case.

JP-A-8-144793

  In general, when the engine is stopped and idling, the VVT may be set to a retarded position from the usual in order to reduce electric power when starting the engine, reduce idling fuel consumption, and the like. On the other hand, after shifting to the load operation, it is necessary to set VVT to a predetermined target advance position at an early stage in order to output a necessary engine torque. Therefore, in this case, due to the high advance speed from the retard position to the target advance position, the engine torque may increase rapidly and a shock may occur. Patent Document 1 does not take into account the above problem.

  The present invention has been made to solve the above-described problems, and it is possible to suppress the occurrence of a shock caused by the high VVT advance speed from the retard position to the target advance position. An object of the present invention is to provide a control device for an internal combustion engine.

  In one aspect of the present invention, a control device for an internal combustion engine mounted on a hybrid vehicle, the engine having a variable valve timing mechanism, and a control for controlling the engine speed based on an engine speed target value increase rate. The control means adds a mountain-shaped increase rate to the engine speed target value increase rate when the valve timing is shifted from the retard position to the target advance position after starting the engine.

  The control device for an internal combustion engine is mounted on a hybrid vehicle and includes an engine and control means. The engine includes a variable valve timing mechanism. The control means is, for example, an ECU (Electronic Control Unit), and controls the engine speed based on the engine speed target value increase rate. The engine speed target value increase rate is a target value of the engine speed increase rate, and is set by a known technique based on detection values from various sensors, for example. Further, the control means adds a mountain-shaped increase rate to the engine speed target value increase rate when the valve timing is shifted from the retard position to the target advance position after the engine is started. The mountain-shaped rising rate has an upper limit value, increases from the initial value to the upper limit value with the passage of time, and then decreases again to the initial value, that is, takes a mountain-shaped value with respect to the passage of time. By doing in this way, the control apparatus of an internal combustion engine can make engine power approach target engine power at an early stage, preventing a shock.

  In one aspect of the control apparatus for an internal combustion engine, the control means is configured to determine the peak increase rate based on a time width until the shift from the retard position to the target advance position and an upper limit value of the peak increase rate. Set the amount of change. By doing in this way, the control apparatus of an internal combustion engine can synchronize the time when the angle increase rate reaches the upper limit and the time when the valve timing reaches the target advance position. Therefore, the control device for the internal combustion engine can quickly approach the target engine power while preventing a shock.

The schematic block diagram of the hybrid vehicle which concerns on this embodiment is shown. The schematic block diagram of an engine is shown. 4 is a time chart at the time of switching from the most retarded position to the target advanced position according to the present embodiment. The time chart at the time of the change from the most retarded angle position which concerns on a comparative example to a target advance angle position is shown. It is a flowchart which shows the outline | summary of the control processing in this embodiment. It is a flowchart of a Yamagata rise rate calculation process. It is an example of the map of an engine speed, the upper limit of a mountain-shaped climb rate, and a rate change amount.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[Device configuration]
FIG. 1 is a schematic configuration diagram of a hybrid vehicle to which an internal combustion engine control device according to each embodiment of the present invention is applied. Note that broken line arrows in the figure indicate signal input / output.

  Hybrid vehicle 100 mainly includes engine (internal combustion engine) 1, axle 2, drive wheels 3, first motor generator MG 1, second motor generator MG 2, power split mechanism 4, inverter 5, and the like. The battery 6 and the ECU 50 are provided.

  The axle 2 is a part of a power transmission system that transmits the power of the engine 1 and the second motor generator MG2 to the wheels 3. The wheels 3 are wheels of the hybrid vehicle 100, and only the left and right front wheels are particularly shown in FIG. The engine 1 is constituted by a gasoline engine or the like, and functions as a power source that outputs the main driving force of the hybrid vehicle 100. The engine 1 is controlled variously by the ECU 50.

  The first motor generator MG1 is configured to function mainly as a generator for charging the battery 6 or a generator for supplying electric power to the second motor generator MG2. Generate electricity. The first motor generator MG1 functions as a regenerative brake at the time of braking (deceleration), for example, and generates electric power by performing a regenerative motion. The second motor generator MG2 is mainly configured to function as an electric motor that assists (assists) the output of the engine 1.

  Power split device 4 corresponds to a planetary gear (planetary gear mechanism) configured with a sun gear, a ring gear, and the like, and is configured to be able to distribute the output of engine 1 to first motor generator MG1 and axle 2. ing.

  Inverter 5 is a DC / AC converter that controls input / output of electric power between battery 6 and first motor generator MG1 and second motor generator MG2.

  The battery 6 is configured to be capable of functioning as a power source for driving the first motor generator MG1 and / or the second motor generator MG2, and the first motor generator MG1 and / or the second motor. It is a storage battery configured to be able to charge power generated by the generator MG2.

  The ECU 50 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown), and performs various controls on each component in the hybrid vehicle 100. Although details will be described later, the ECU 50 corresponds to the control device for an internal combustion engine in the present invention, and functions as a control means.

  Below, after demonstrating schematic structure of the engine 1, the process which ECU50 performs is demonstrated concretely.

[Schematic configuration of the engine]
FIG. 2 is a schematic configuration diagram of the engine 1 shown in FIG. A solid line arrow in the figure shows an example of a gas flow.

  The engine 1 mainly includes an intake passage 11, a throttle valve 12, a fuel injection valve 14a, an intake valve 14b, an ignition plug 14c, an exhaust valve 14d, a variable valve timing mechanism 14e, a cylinder 15a, and a piston. 15c, a connecting rod 15d, and an exhaust passage 16. In FIG. 2, only one cylinder 15a is shown for convenience of explanation, but the engine 1 actually has a plurality of cylinders 15a.

  Intake air (air) introduced from outside passes through the intake passage 11, and the throttle valve 12 adjusts the flow rate of intake air passing through the intake passage 11. The opening degree of the throttle valve 12 is controlled by a control signal supplied from the ECU 50. The intake air that has passed through the intake passage 11 is supplied to the combustion chamber 15b. The fuel injected by the fuel injection valve (injector) 14a is supplied to the combustion chamber 15b.

  Further, the combustion chamber 15b is provided with an intake valve 14b and an exhaust valve 14d. The intake valve 14b opens / closes to control conduction / interruption between the intake passage 11 and the combustion chamber 15b. The intake valve 14b is controlled by a variable valve timing mechanism 14e for valve timing (valve opening timing or valve closing timing). For example, the intake valve 14b is switched between an advance angle and a retard angle of the valve timing.

  The variable valve timing mechanism 14e is controlled by a control signal supplied from the ECU 50. On the other hand, the exhaust valve 14d opens and closes to control conduction / interruption between the exhaust passage 16 and the combustion chamber 15b. Hereinafter, the variable valve timing mechanism is also expressed as “VVT”.

  In the combustion chamber 15b, the air-fuel mixture of intake air and fuel supplied as described above is burned by being ignited by the spark plug 14c. In this case, the piston 15c reciprocates by combustion, the reciprocating motion is transmitted to the crankshaft (not shown) via the connecting rod 15d, and the crankshaft rotates. Exhaust gas generated by combustion in the combustion chamber 15 b is exhausted from the exhaust passage 16.

  In the following description, the “target advance position” refers to the target value of the valve timing controlled by the ECU 50, and the “most retarded position” refers to the most retarded valve timing controlled by the ECU 50. A certain valve timing is indicated, and the “VVT advance amount” indicates the advance amount of the valve timing when the most retarded position is set to 0. The target advance position and the most retarded position are set for each vehicle type, for example, through experiments.

  As a premise for the following explanation, when the engine 1 is stopped, the ECU 50 sets the VVT to the most retarded position in order to reduce the electric power when the engine 1 is restarted. Further, at the time of idling, the ECU 50 controls the VVT to the retard side in order to reduce pump loss due to opening / closing of the intake valve 14 or the like.

[Control method]
Next, the control of the ECU 50 in this embodiment will be specifically described. When the ECU 50 adjusts the valve timing from the most retarded position to the target advanced position after the engine 1 is started, it is referred to as an engine speed increase rate command value (hereinafter referred to as “engine speed target value increase rate Re”). )), An ascending rate (hereinafter referred to as “mountain ascent rate Rm”) is added. That is, the ECU 50 temporarily increases the engine speed target value increase rate Re. Thereby, ECU50 makes engine power approach target engine power at an early stage, preventing the shock of vehicle 100. FIG.

  In the following, after describing the process of adding the mountain-shaped increase rate Rm to the engine speed target value increase rate Re, the upper limit value of the mountain-shaped increase rate (hereinafter referred to as “upper limit value Lrm”) and the amount of change (hereinafter referred to as “upper limit value Lrm”). A specific determination method of “rate change amount drm” will be described.

(Addition of Yamagata climb rate)
The specific contents of the process in which the ECU 50 adds the mountain-shaped increase rate Rm to the engine speed target value increase rate Re will be described below with reference to FIG. FIG. 3 is an example of a time chart at the time of switching from the most retarded position to the target advanced position in the present embodiment.

  FIG. 3 shows, in order from the top, the accelerator opening, the engine speed, the VVT advance amount, the engine speed target value increase rate Re, and the torque of the first motor generator MG1 (hereinafter referred to as “MG1 torque”). The torque of second motor generator MG2 (hereinafter referred to as “MG2 torque”) and the driving force torque are shown. In FIG. 4, a graph B2 corresponds to a command value for engine speed, a graph B3 corresponds to an actual value for engine speed, and a graph B4 corresponds to a required value for engine speed. Graph B8 corresponds to the required value of MG2 torque, graph B9 corresponds to the command value of MG2 torque, and graph B10 corresponds to the limit value (upper limit guard) of MG2 torque. The above limit value is set to, for example, the minimum value of the supply torque (specifically, equivalent to the power obtained by combining the power generation power of the first motor generator MG1 and the power upper limit of the battery 6) and the maximum torque. The Graph B11 corresponds to the required value of drive torque, and graph B12 corresponds to the actual value of drive torque.

  First, after the start of the time chart, the accelerator opening gradually increases based on a user operation or the like. Then, the ECU 50 starts the load operation of the engine 1 at a predetermined time t11. Thereby, the required value of engine speed becomes high.

  Then, from a predetermined time t12 after time t11 to a predetermined time t13, the ECU 50 increases the VVT advance amount. That is, the ECU 50 shifts the valve timing from the most retarded position to the target advanced position from time t12 to time t13. Hereinafter, the time for increasing the VVT advance amount (here, corresponding to time t12) is referred to as “VVT advance start time”.

  Further, the ECU 50 adds the mountain-shaped increase rate Rm to the engine speed target value increase rate Re over a period T1 from the time t12 when the VVT advance amount is increased to a predetermined time t14. At this time, the ECU 50 synchronizes the time at which the upper limit value Lrm of the mountain climb rate Rm is added with the time t13 when the VVT advance amount reaches the target advance position.

  In this way, the ECU 50 adds the angle increase rate Rm to the engine speed target value increase rate Re, so that the actual value of the engine speed (see graph B3) is quickly obtained as the requested engine speed (see graph B4). ) Can be reached. Therefore, the ECU 50 can bring the engine power close to the target engine power at an early stage. Further, the ECU 50 can reduce the fluctuation of the MG1 torque caused by the rapid increase of the engine torque by reducing the fluctuation of the deviation between the actual value of the engine speed and the command value of the engine speed (see graph B2). it can. Therefore, the ECU 50 can suppress sudden fluctuations in the drive torque, prevent a shock, and improve acceleration performance and the like.

  This effect will be further supplemented with reference to FIG. FIG. 4 is a time chart at the time of switching from the most retarded position to the target advanced position when the angle increase rate Rm is not added to the engine speed target value increase rate Re (hereinafter referred to as “comparative example”). It is an example.

  FIG. 4 shows, in order from the top, the accelerator opening, the engine speed, the VVT advance amount, the engine speed target value increase rate Re, the MG1 torque, the MG2 torque, and the driving force torque. In FIG. 4, a graph C2 corresponds to a command value for engine speed, a graph C3 corresponds to an actual value for engine speed, and a graph C4 corresponds to a required value for engine speed. Graph C8 corresponds to the required value of MG2 torque, graph C9 corresponds to the command value of MG2 torque, and graph C10 corresponds to the upper limit guard of MG2 torque. The graph C11 corresponds to the required value of the driving torque, and the graph C12 corresponds to the actual value of the driving torque.

  As shown in FIG. 4, the ECU 50 increases the VVT advance amount from time t12 to time t13. As a result, the engine torque increases. In particular, when the increasing rate of the VVT advance amount is fast, the engine torque increases rapidly. As a result, in FIG. 4, there is a deviation between the command value and the actual value of the engine speed. Further, the MG1 torque varies greatly from time t12 to time t13 due to feedback control for eliminating the deviation. Accordingly, the fluctuations in the MG2 torque and the driving force torque increase near time t13, and a shock occurs.

  On the other hand, in the time chart shown in FIG. 3, the ECU 50 adds the mountain-shaped increase rate Rm to the engine speed target value increase rate Re, so that the engine 1 and the first motor generator MG1 This is used to increase the inertia. As a result, the ECU 50 can approach the target engine power at an early stage while preventing a shock. As a result, the output of the battery 6 can be suppressed and fuel consumption can be improved.

(How to determine the upper limit of the Yamagata climb rate)
Next, a method for determining the upper limit value Lrm of the mountain-shaped increase rate Rm to be added to the engine speed target value increase rate Re will be described.

  The ECU 50 determines the upper limit value Lrm as a deviation between the torque generated in the engine 1 at the retarded position (the most retarded position in the above example) and the torque generated in the engine 1 at the target advanced position (hereinafter simply “ It is determined on the basis of “torque deviation H”.

  I will supplement this. As described above, a shock occurs due to an increase in engine torque at the time of switching from the most retarded position to the target advanced position. As the engine torque increases, the variation in MG1 torque and the like increases. Therefore, the ECU 50 sets the upper limit value Lrm according to the torque deviation H. When the torque deviation H is large, the ECU 50 suppresses the occurrence of shock by increasing the upper limit value Lrm, so that the engine power can be quickly increased to the target engine power. Can be approached.

  Specifically, for example, the ECU 50 obtains the upper limit value Lrm from the following equation (1) based on the equation of motion of rotational motion.

Upper limit Lrm = torque deviation H / moment of inertia (Formula 1)
In this case, the moment of inertia is set to, for example, the moment of inertia between engine 1 and first motor generator MG1 converted to the engine shaft. In this way, the ECU 50 can specifically determine the upper limit value Lrm.

(How to determine the amount of change in the Yamagata rise rate)
Next, a method for determining the rate change amount drm of the mountain-shaped increase rate Rm to be added to the engine speed target value increase rate Re will be described. As described above, the ECU 50 increases the engine speed target value increase rate Re with the start of the increase in the VVT advance amount in order to suppress the increase in the engine torque due to the increase in the VVT advance amount, and the VVT advance angle. When the amount reaches the target advance position, it is necessary to match the peak (that is, the upper limit value Lrm) of the mountain rising rate Rm.

  Therefore, the ECU 50 adjusts the rate change amount drm from the VVT advance amount increase start time (corresponding to time t12 in FIG. 3) to the time when the target advance angle position is reached (corresponding to time t13 in FIG. 3). Is set according to the time width and the upper limit value Lrm.

  More specifically, the ECU 50 obtains the rate change drm by the following equation (2).

Rate change amount drm = upper limit value Lrm / {(target advance position−most retarded position) / advance speed} (Formula 2)
By doing so, the ECU 50 can synchronize the time when the VVT advance amount reaches the target advance position and the time when the mountain climb rate Rm reaches the upper limit value Lrm. Therefore, the ECU 50 can bring the engine power close to the target engine power at an early stage while preventing a shock.

(Processing flow)
Next, a processing procedure in the present embodiment will be described. Here, first, an outline of a processing procedure performed by the ECU 50 in the present embodiment will be described, and then a specific processing procedure for calculating the mountain-shaped climb rate Rm will be described. The ECU 50 repeatedly executes the process of the flowchart according to a predetermined cycle.

1. Outline First, the ECU 50 determines whether or not the load operation has started after the engine 1 is started (step S101). When the engine 1 is started and the load operation is started (step S101; Yes), the ECU 50 advances the process to step S102. On the other hand, when it is before the start of the engine 1 or before the load operation is started (step S101; No), the ECU 50 ends the process of the flowchart.

  Next, the ECU 50 calculates the engine speed target value increase rate Re (step S102).

  Then, the ECU 50 calculates the VVT advance start time based on the intermittent time (step S103). In general, in the case of a hydraulic VVT, the VVT advance start time varies depending on the intermittent time of the engine 1. Therefore, the ECU 50 calculates an appropriate VVT advance start time based on the intermittent time.

  Next, the ECU 50 determines whether or not a predetermined time width has elapsed since the start of the engine 1 (step S104). For example, the predetermined time width is set to a value obtained by subtracting a compensation value such as a delay in feedback control of the engine speed or a deviation from the actual VVT advance start time from the VVT advance start time calculated in step S103. The

  Then, the ECU 50 adds the mountain-shaped increase rate Rm to the engine speed target value increase rate Re (step S105). Thereby, ECU50 can suppress the generation | occurrence | production of the shock etc. resulting from the engine torque rapid increase by the increase in VVT advance amount.

2. Calculation of Yamagata Ascent Rate Next, the procedure for calculating the Yamagata ascent rate Rm will be described. FIG. 6 is an example of a flowchart for calculating the mountain-shaped increase rate Rm executed by the ECU 50. The ECU 50 repeatedly executes the process of this flowchart, for example, at the time of the process of step S105 of the flowchart shown in FIG.

  First, the ECU 50 determines whether or not a predetermined time width has elapsed since the engine was started (step S201). The predetermined time width is set to be the same as the predetermined time width in step S104, for example.

  When a predetermined time width has elapsed since the engine was started (step S201; Yes), the ECU 50 determines whether or not the mountain climb rate calculation process has been performed for the first time since the engine was started (step S202). That is, the ECU 50 determines whether or not the processing after step S202 is performed for the first time after the engine is started.

  On the other hand, when the predetermined time width has not elapsed since the engine was started (step S201; No), the ECU 50 ends the process of the flowchart.

  Then, when the mountain-shaped increase rate calculation process is performed for the first time since the engine start (step S202; Yes), the ECU 50 calculates the upper limit value Lrm and the rate change amount drm from the engine speed and the like, and selects the addition process (step) S203).

  On the other hand, when the angle increase rate calculation process after engine startup has already been performed (step S202; No), the ECU 50 determines whether or not the addition process has been selected (step S204).

  If the addition process has been selected (step S204; Yes), the ECU 50 adds the rate change amount drm to the mountain rising rate Rm (step S205).

  Next, the ECU 50 determines whether or not the mountain rising rate Rm is larger than the upper limit value Lrm (step S206).

  When the mountain-shaped increase rate Rm is larger than the upper limit value Lrm (step S206; Yes), the ECU 50 selects a subtraction process from the next time (step S207). At this time, the ECU 50 sets, for example, the mountain rising rate Rm to the upper limit value Lrm. Then, the ECU 50 ends the process of the flowchart. As a result, the ECU 50 performs a subtraction process for the mountain rising rate Rm when the process of the flowchart is executed from the next time onward.

  On the other hand, when the mountain-shaped increase rate Rm is equal to or lower than the upper limit value Lrm (step S206; No), the ECU 50 ends the process of the flowchart while continuously selecting the addition process.

  On the other hand, when it is determined that the addition process is not selected (step S204; No), that is, when the subtraction process is selected in step S207, the ECU 50 subtracts the rate change amount drm from the mountain rising rate Rm (step S208). ).

  Next, the ECU 50 determines whether or not the mountain rising rate Rm is smaller than 0 (step S209). When the mountain-shaped increase rate Rm is smaller than 0 (step S209; Yes), the ECU 50 sets the mountain-shaped increase rate Rm to 0 (step S210), and the process of the flowchart is ended. Then, the ECU 50 ends the calculation process of the mountain rising rate Rm.

  On the other hand, when the mountain-shaped increase rate Rm is 0 or more (step S209; No), the ECU 50 starts the process of the flowchart again after completing the process of the flowchart, and continues the calculation process of the mountain-shaped increase rate Rm.

  By doing as described above, the ECU 50 specifically calculates the mountain-shaped increase rate Rm in which the time when the VVT advance amount reaches the target advance position and the time when the mountain-shaped increase rate Rm reaches the upper limit value Lrm are synchronized. be able to.

[Modification]
In the above description, the ECU 50 calculates the upper limit value Lrm and the rate change amount drm of the mountain rising rate Rm based on the formulas (1) and (2). However, the method to which the present invention is applicable is not limited to this. Instead of this, the ECU 50 may calculate the upper limit value Lrm and the rate change amount drm based on a map previously stored in a memory or the like. Also by this, the ECU 50 can appropriately set the upper limit value Lrm and the rate change amount drm.

  Hereinafter, a specific example of the map described above will be shown. FIG. 7 is an example of a map of the engine speed, the upper limit value Lrm, and the rate change amount drm. In FIG. 7, the rate change amount drm is added / subtracted to / from the mountain-shaped increase rate Rm every 8 milliseconds, and the mountain-shaped increase rate Rm is added / subtracted to / from the engine speed target value increase rate Re every 8 milliseconds.

  As shown in FIG. 7, a rate change amount drm and an upper limit value Lrm for each engine speed are set in the map. Specific values of the rate change amount drm and the upper limit value Lrm for each engine speed are set to appropriate values based on, for example, experiments.

  Therefore, after acquiring the engine speed, the ECU 50 determines, for example, which engine speed on the map is closer to the acquired engine speed, and sets the rate change amount drm and the upper limit value Lrm corresponding to the engine speed. Extract.

  As described above, the ECU 50 can obtain the appropriate upper limit value Lrm and the rate change amount drm based on the engine speed by holding the map shown in FIG. 7 in a memory or the like.

1 engine (internal combustion engine)
3 Drive Wheel 4 Power Dividing Mechanism 5 Inverter 6 Battery 12 Throttle Valve 14b Intake Valve 14d Exhaust Valve 14e Variable Valve Timing Mechanism 50 ECU
MG1 first motor generator MG2 second motor generator 100 hybrid vehicle

Claims (2)

A control device for an internal combustion engine mounted on a hybrid vehicle,
An engine having a variable valve timing mechanism;
Control means for controlling the engine speed based on the engine speed target value increase rate,
The control means adds a mountain-shaped increase rate to the engine speed target value increase rate when the valve timing is shifted from the retard position to the target advance position after the engine is started. The control apparatus of the internal combustion engine described in 1.   2. The internal combustion engine according to claim 1, wherein the control unit sets the amount of change in the mountain-shaped climb rate based on a time width until the shift from the retard position to the target advance position and an upper limit value of the mountain-shaped climb rate. Engine control device.

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