JP2007292045A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimally control action of a valve according to limitation such as voltage of a boost converter in a system for opening/closing the valve by driving a motor. <P>SOLUTION: The control device for the internal combustion engine has valve gears 48A, 48B for conducting open/close drive of the valve element 36 equipped by each cylinder by motors 54A, 54B, a target operating angle determination means for determining a target operation angle at the time of driving the valve element 36 according to limitation of the driving load of the motors 54A, 54B or rotation speed of the motors 54A, 54B and a control means for driving the motors 54A, 54B based on the target operation angle. As the target operation angle of the valve element 36 is determined according to the limitation of the driving load and the rotation speed of the motors 54A, 54B, the driving load and the rotation speed of the motors 54A, 54B can be prevented from exceeding their allowable ranges and reliability of the internal combustion engine 10 can be enhanced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine.

  Conventionally, for example, in JP-A-2005-54732, in a configuration in which a valve is opened and closed using a driving force of a motor, when the camshaft and the crankshaft rotate asynchronously, the valve is stopped or low lift control is performed. A method of switching to is disclosed.

JP 2005-54732 A

  However, for example, when the target operating angle / lift amount is controlled during the swing operation by the driving force of the motor, the target operating angle / lift amount may exceed the capacity limit of the boost converter. For this reason, the valve cannot be operated normally, and there is a problem that the working angle / lift amount is restricted. Further, there is a case where the boosting by the boosting converter is performed exceeding the target of the working angle / lift amount, which causes a problem of reducing the efficiency of the system.

  In addition, when the motor drive load is high or when the ambient temperature of the motor is high, there is a problem that the temperature of the motor is likely to rise and the allowable temperature may be exceeded.

  The present invention has been made to solve the above-described problems. In a system that opens and closes a valve by driving a motor, the target voltage value of the boost converter is determined according to restrictions such as the capability limit of the boost converter. The purpose is to optimally control the operation of the valve. Another object of the present invention is to reliably prevent the motor temperature from exceeding an allowable temperature in the system.

  In order to achieve the above object, according to a first aspect of the present invention, there is provided a valve driving means for opening and closing a valve body included in each cylinder by a motor, and the valve according to a limitation on a driving load of the motor or a rotation speed of the motor. A target operating angle determining means for determining a target operating angle for driving the body, and a control means for driving the motor based on the target operating angle are provided.

  In a second aspect based on the first aspect, the booster circuit boosts the voltage supplied to the motor, and the booster circuit supplies the motor to the motor according to the driving load of the motor or the rotational speed of the motor. It further comprises target voltage setting means for setting a target value of voltage, and boost control means for controlling the boosting operation of the booster circuit based on the target value.

  In a third aspect based on the second aspect, the target operating angle determining means is configured to determine the target operating angle based on a limit of the driving load of the motor or the rotational speed of the motor and a limit value of the capacity of the booster circuit. It is characterized by determining a corner.

  According to a fourth invention, in the second or third invention, the target working angle determining means is configured to control the motor driving load determined from an output voltage value of the booster circuit or a limitation on a rotation speed of the motor. A target operating angle is determined.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the valve driving means drives a camshaft for driving the valve body in a swing driving mode, and limits a driving load of the motor. And a lift amount determining means for determining a target lift amount for driving the valve body according to the control mechanism, wherein the control means drives the motor based on the target operating angle and the target lift amount. And

The sixth invention is a control device for an internal combustion engine,
A valve driving means for opening and closing a valve body included in each cylinder by a motor;
Target valve opening characteristic correcting means for correcting the target valve opening characteristic of the valve body so that the temperature of the motor is equal to or lower than the allowable temperature when the temperature of the motor may exceed the allowable temperature;
Control means for driving the motor based on the corrected target valve opening characteristic;
It is provided with.

The seventh invention is the sixth invention, wherein
The target valve opening characteristic correcting means includes a working angle correcting means for increasing a target working angle of the valve body when the temperature of the motor may exceed an allowable temperature.
A throttle valve provided in an intake passage of the internal combustion engine;
Throttle opening control means for reducing the opening of the throttle valve so that the engine torque does not change when the target operating angle is increased by the operating angle correction means;
Is further provided.

The eighth invention is the sixth or seventh invention, wherein
When the camshaft for driving the valve element is driven in the swing drive mode, the target valve opening characteristic correction means may be configured to detect the cam when the temperature of the motor may exceed an allowable temperature. Drive mode changing means for changing the drive mode of the shaft to the normal rotation drive mode is included.

The ninth invention is a control device for an internal combustion engine,
Valve drive means for opening and closing a valve body included in each cylinder of the internal combustion engine by a motor;
A transmission provided between the internal combustion engine and a drive shaft of the vehicle;
An engine speed suppression means for reducing the engine speed by changing the gear ratio of the transmission to a high speed side when the temperature of the motor may exceed an allowable temperature;
It is provided with.

  According to the first aspect of the invention, the target operating angle of the valve body is determined in accordance with the restrictions on the driving load and rotation speed of the motor. . Therefore, the valve body can be reliably driven, and the reliability of the internal combustion engine can be improved.

  According to the second invention, since the target value of the voltage supplied from the booster circuit to the motor is set according to the driving load and rotation speed of the motor, the booster by the booster circuit can be minimized, and the system Efficiency can be improved.

  According to the third aspect of the invention, since the target working angle is determined based on the limit of the driving load or rotation speed of the motor and the limit value of the booster circuit capability, the target operating angle exceeds the limit value of the booster circuit capability. Can be prevented. Therefore, it is possible to reliably drive the valve body within the capacity of the booster circuit.

  According to the fourth aspect of the invention, the target operating angle is determined in accordance with the motor driving load or the rotational speed limit determined from the output voltage value of the booster circuit, so that the valve body is reliably within the range of the output voltage of the booster circuit. Can be driven.

  According to the fifth aspect, since the camshaft for driving the valve body is driven in the swing drive mode, the operating angle and the lift amount of the valve body can be optimally controlled. Further, since the target lift amount of the valve body is determined according to the limitation of the motor driving load, it is possible to prevent the motor driving load from exceeding the allowable range.

  According to the sixth aspect of the invention, when the motor temperature may exceed the allowable temperature, the target valve opening characteristic of the valve body is corrected so that the motor temperature is equal to or lower than the allowable temperature, and the corrected target is corrected. The motor can be driven based on the valve opening characteristics. Thereby, the temperature of the motor can be reliably prevented from exceeding the allowable temperature, and the reliability of the internal combustion engine can be improved.

  According to the seventh aspect, the target operating angle of the valve element can be increased when the motor temperature may exceed the allowable temperature. When the operating angle is increased, the acceleration and deceleration of the motor are reduced and the effective value of the motor torque is reduced, so that the amount of heat generated by the motor is reduced. Therefore, the temperature rise of the motor can be effectively suppressed. According to the seventh invention, when the target operating angle is increased as described above, the opening of the throttle valve provided in the intake passage of the internal combustion engine can be reduced. Thereby, even if the operating angle changes, the engine torque can be prevented from changing as much as possible. Therefore, it is possible to reliably prevent an increase in engine torque unintended by the driver, and to obtain good drivability.

  According to the eighth aspect of the present invention, when the camshaft for driving the valve element is driven in the swing drive mode, the camshaft drive mode may be used if the motor temperature may exceed the allowable temperature. Can be changed to the forward rotation drive mode. As a result, the effective torque value of the motor can be greatly reduced and the amount of heat generation is greatly reduced, so that the motor temperature can be more reliably prevented from exceeding the allowable temperature.

  According to the ninth aspect, when the motor temperature may exceed the allowable temperature, the engine speed can be reduced by changing the transmission gear ratio to the high speed side. When the engine rotational speed is decreased, the rotational speed (average rotational speed) of the cam is decreased, and as a result, the rotational speed of the motor (average rotational speed) can be decreased. As a result, since the amount of heat generated by the motor can be reduced, it is possible to reliably prevent the motor temperature from exceeding the allowable temperature.

  Several embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted. The present invention is not limited to the following embodiments.

Embodiment 1 FIG.
FIG. 1 is a schematic view showing a configuration of a system including a valve operating apparatus for an internal combustion engine according to an embodiment of the present invention. An intake passage 12 and an exhaust passage 14 communicate with the internal combustion engine 10. The intake passage 12 includes an air filter 16 at an upstream end. The air filter 16 is assembled with an intake air temperature sensor 18 for detecting the intake air temperature THA (that is, the outside air temperature). An exhaust purification catalyst 32 is disposed in the exhaust passage 14.

  An air flow meter 20 is disposed downstream of the air filter 16. A throttle valve 22 is provided downstream of the air flow meter 20. A throttle sensor 24 that detects the throttle opening degree TA and an idle switch 26 that is turned on when the throttle valve 22 is fully closed are disposed in the vicinity of the throttle valve 22. A surge tank 28 is provided downstream of the throttle valve 22. Further, a fuel injection valve 30 for injecting fuel into the intake port of the internal combustion engine 10 is disposed further downstream of the surge tank 28.

  The internal combustion engine 10 includes an intake valve 36 and an exhaust valve 38. A valve operating device 48 for driving the intake valve 36 is connected to the intake valve 36. The exhaust valve 38 is connected to a valve operating device 50 for driving the exhaust valve 38.

  An ignition plug is provided in the cylinder of the internal combustion engine 10 to ignite the fuel sprayed into the combustion chamber. Further, a piston 44 that reciprocates inside the cylinder is provided in the cylinder. The piston 44 is connected to a crankshaft 46 that is driven to rotate by the reciprocating motion. The vehicle drive system and accessories (air conditioner compressor, alternator, torque converter, power steering pump, etc.) are driven by the rotational torque of the crankshaft 46.

  As shown in FIG. 1, the control device of the present embodiment includes an ECU (Electronic Control Unit) 40. In addition to the various sensors described above, the ECU 40 includes a KCS sensor that detects the occurrence of knocking, a throttle opening, an engine speed, an exhaust temperature, a cooling water temperature, a lubricating oil temperature in order to grasp the operating state of the internal combustion engine 10. Various sensors (not shown) for detecting the catalyst bed temperature and the like are connected. The ECU 40 is connected to each actuator and sensor provided in the fuel injection valve 30 and the valve gears 48 and 50 described above.

  FIG. 2 is a schematic diagram showing the configuration around the intake valve 36 and the valve gear 48, and mainly shows the configuration around the cylinder head. In FIG. 2, the exhaust valve 38 and the valve operating device 50 are not shown, but the intake side valve operating device 48 and the exhaust side valve operating device 50 basically have the same configuration. Here, it is assumed that each cylinder of the internal combustion engine 10 is provided with two intake valves 36 and two exhaust valves 38.

  The internal combustion engine 10 of the present embodiment includes four cylinders (# 1 to # 4), and the explosion stroke is performed in the order of # 1 → # 3 → # 4 → # 2. The valve operating device 48 includes two devices (the valve operating device 48A and the valve operating device 48B). The valve gear 48A drives the intake valve 36 provided in the # 2 cylinder and the # 3 cylinder, and the valve device 48B drives the intake valve 36 provided in the # 1 cylinder and the # 4 cylinder.

  The valve gear 48A includes an electric motor (hereinafter referred to as a motor) 54A as a drive source, a gear train 56A as a transmission mechanism for transmitting the rotational motion of the motor 54A, and the rotational motion transmitted from the gear train to the intake valve 36. And a camshaft 58A for converting into a linear opening / closing motion. Similarly, the valve gear 48B includes a motor 54B, a gear train 56B, and a camshaft 58B. The configuration of the gear train 56B is the same as that of the gear train 56A.

  For the motors 54A and 54B, for example, a DC brushless motor capable of controlling the rotation speed is used. The motors 54A and 54B have built-in position detection sensors such as a resolver and a rotary encoder for detecting their rotational positions. A cam drive gear 60 that rotates integrally with the camshafts 58A and 58B and a cam 62 that also rotates integrally with the camshafts 58A and 58B are provided on the outer periphery of the camshafts 58A and 58B.

  The gear train 56A transmits the rotation of the motor gear 64A attached to the output shaft 55 of the motor 54A to the cam drive gear 60 of the camshaft 58A via the intermediate gear 66A. The gear train 56A may be configured such that the motor gear 64A and the cam drive gear 60 rotate at equal speeds, or may be configured to increase or decrease the speed of the cam drive gear 60 relative to the motor gear 64A. . Similarly, the gear train 56B transmits the rotation of the motor gear 64B attached to the output shaft of the motor 54B to the cam drive gear 60 of the camshaft 58B via the intermediate gear 66B (not shown in FIG. 2).

  As shown in FIG. 2, the camshaft 58A is disposed above the intake valves 36 of the # 2 and # 3 cylinders, and each of the intakes of the # 2 and # 3 cylinders is provided by four cams 62 provided on the camshaft 58A. The valve 36 is driven to open and close. In addition, the camshaft 58B is divided into two parts and is disposed above the intake valves 36 of the # 1 and # 4 cylinders, and the # 1 and # 4 cylinders are provided by four cams 62 provided on the camshaft 58B. Each intake valve 36 is driven to open and close. The camshaft 58B divided into two is connected by a connecting member 58C inserted through a through hole provided at the center of the camshaft 58A, and is configured to rotate integrally. For convenience of explanation, FIG. 2 shows a state in which the camshaft 58A and the two camshafts 58B are separated from each other.

  FIG. 3 is a schematic diagram showing how the intake valve 36 is driven by the cam 62. The cam 62 is formed as a kind of plate cam in which a nose 62a is formed by inflating a part of an arc-shaped base circle 62b coaxial with the camshafts 58A, 58B radially outward. The profile of the cam 62 is set so that a negative curvature does not occur over the entire circumference, that is, a convex curved surface is drawn outward in the radial direction.

  As shown in FIG. 2, each intake valve 36 includes a valve shaft 36a. Each cam 62 faces a retainer 68 provided at one end of the valve shaft 36 a of the intake valve 36. Each intake valve 36 is urged toward the cam 62 by a compression reaction force of a valve spring (not shown), and when the base circle 62b of the cam 62 and the retainer 68 are opposed to each other, a valve seat (not shown) of the intake port. The intake valve 36 is in close contact with the intake port and the intake port is closed.

  When the rotational motion of the motors 54A, 54B is transmitted to the camshafts 58A, 58B via the gear trains 56A, 56B, the cam 62 rotates together with the camshafts 58A, 58B, and the nose 62a passes over the retainer 68. The retainer 68 is pushed down, and the intake valve 36 is driven to open and close against the valve spring.

  3A and 3B show two drive modes of the cam 62. FIG. In the drive mode of the cam 62, the motors 54A and 54B are continuously rotated in one direction to move the cam 62 to the maximum lift position as shown in FIG. 3A, that is, the nose 62a of the cam 62 is the counterpart component (in this case). Is a forward drive mode for continuously rotating in the forward rotation direction (in the direction of the arrow in FIG. 3A) beyond the position in contact with the retainer 68), and the motor 54A before reaching the maximum lift position in the forward drive mode. , 54B and a swing drive mode in which the cam 62 is reciprocated as shown in FIG.

  In the forward rotation drive mode, the operating angle of the intake valve 36 is controlled by varying the rotational speed of the cam 62 with respect to the rotation of the crankshaft 46. In the swing drive mode, the maximum lift amount and operating angle of the intake valve 36 can be controlled by controlling the angular range in which the cam 62 swings together with the rotational speed of the cam 62.

  The forward rotation drive mode includes a constant speed mode in which the cam 62 is rotated at a constant speed when the engine speed is constant, and a variable speed mode in which the speed of the cam 62 is variable. The variable speed mode is a mode in which, for example, the rotational speed of the cam 62 is slowed while the cam 62 pushes down the intake valve 36, and the rotational speed of the cam 62 is fastened while the cam 62 is not pushing down the intake valve 36. is there. In the variable speed mode, the rotational speed of the cam 62 is increased while the cam 62 is pushing down the intake valve 36, and the rotational speed of the cam 62 is decreased while the cam 62 is not pushing down the intake valve 36. it can. Such control makes it possible to freely set the operating angle of the intake valve 36 with respect to the rotation angle of the crankshaft 46.

  According to the control as described above, the intake valve 36 can be driven with an optimal lift amount and operating angle according to the operating state. FIG. 4 is a schematic diagram showing the relationship between the engine speed and output torque of the internal combustion engine 10 and the drive mode of the cam 62. As shown in FIG. 4, the drive mode of the cam 62 is selectively used in association with the engine speed and the output torque. Basically, the swing drive mode is selected in the low rotation range, and the normal rotation drive mode is selected in the high rotation range. As a result, control is performed to reduce the lift amount and operating angle of the intake valve 36 in the low rotation range, and increase the lift amount and operating angle of the intake valve 36 in the high rotation range, depending on the engine speed and output torque. It becomes possible to send the optimal amount of air into the engine cylinder.

  FIG. 5 is a schematic diagram showing in detail two types of cams 62 provided on the camshaft 58A. As shown in FIG. 5, on the camshaft 58A, a cam 62 for driving the intake valve 36 for the # 2 cylinder and a cam 62 for driving the intake valve 36 for the # 3 cylinder are at an angular position of 180 °. Are spaced apart. In the four-cylinder internal combustion engine, the explosion strokes are performed in the order of # 1, # 3, # 4, and # 2 during the crank angle of 720 °. Therefore, the intake stroke of the # 2 cylinder and the # 3 cylinder is 360 ° of the crank angle. Done every time. In the valve gear 48A, the # 2-cylinder cam 62 and the # 3-cylinder cam 62 alternately drive the # 2-cylinder intake valve 36 and the # 3-cylinder intake valve 36 at every crank angle of 360 °. The camshaft 58A is rotated or swung. Similarly, the camshaft 58B is provided with two types of cams 62 for driving the # 1 and # 4 cylinder intake valves 36, and the valve gear 48B rotates or swings the camshaft 58B. Thus, the intake valve 36 for the # 1 cylinder and the intake valve 36 for the # 4 cylinder are driven.

  FIG. 6 is a schematic diagram showing a drive system 70 that drives the motors 54A and 54B of the valve gears 48A and 48B, and a boost converter 72 that supplies power to the drive system 70. As shown in FIG. 6, the drive system 70 includes an ECU 40 that controls driving of the motors 54 </ b> A and 54 </ b> B, a driver 76, and a sensor 78. The driver 76 is connected to motors 54A and 54B of valve gears 48A and 48B. In response to a command from the ECU 40, the driver 76 drives the motors 54A and 54B in a predetermined mode. The sensor 78 is built in the motors 54A and 54B, and detects the angular positions and rotational speeds of the camshafts 58A and 58B.

  An input power source (battery) 80 is connected to the boost converter 72. The boost converter 72 includes a PIC microcomputer 82, a coil 84, and a switch 86. Boost converter 72 performs voltage control (feed forward and feedback) with PIC microcomputer 82. The boost converter 72 has a function of determining the ratio of the on / off time of the switch 86 based on the result of the control by the PIC microcomputer 82, boosting the voltage of the input power supply 80, and supplying the boosted voltage to the drive system 70.

  When the system of this embodiment is mounted on a hybrid vehicle, the voltage of the input power supply 80 is normally about 200V, and varies in the range of about 170V to 240V depending on the driving state. The voltage of the input power supply 80 is boosted to about 280 V in response to a command from the PIC microcomputer 82, and is output to the drive system 70 via the sensor 88. Drive system 70 receives electric power from boost converter 72 and controls motors 54A and 54B based on a command from ECU 40.

  FIG. 7 is a characteristic diagram showing the relationship between the output voltage of boost converter 72, the number of rotations of motors 54A and 54B, and the load. In FIG. 7, the vertical axis indicates the output voltage of the boost converter 72, and the horizontal axis indicates the rotation speed of the motors 54A and 54B. Further, the slope of the characteristic shown in FIG. 7 represents the load on the motors 54A and 54B.

  As shown in FIG. 7, when the output voltage of boost converter 72 is 280 V, when motors 54A and 54B are driven with a load of characteristic X1 indicated by a solid line in FIG. 7, the maximum rotational speed of motors 54A and 54B is reduced to r1. Can be raised.

  On the other hand, in the case where the load is the characteristic X1 shown in FIG. 7, when the motors 54A and 54B are operated at the maximum rotation speed r2, the output voltage of the boost converter 72 is about 200V, and the output voltage is boosted to 280V. There is no need to do this. Similarly, when the load is reduced to the characteristic X2 indicated by the broken line in FIG. 7, even if the maximum rotational speed of the motors 54A and 54B is r1, the output voltage of the boost converter 72 is sufficient to be about 200V. It is.

  For this reason, in this embodiment, the optimum output voltage of the boost converter 72 is determined according to the operation pattern of the motors 54A and 54B, and the boost operation by the boost converter 72 is controlled based on this. Thereby, the boosting operation by boost converter 72 can be minimized, and the efficiency of the system can be improved.

  That is, in the present embodiment, boosting of the boost converter 72 is performed according to the operation angle of the intake valve 36 and the operation pattern of the lift amount. After boosting, the operating angle and lift amount of the intake valve 36 are determined according to the rotational speeds and drive loads of the motors 54A and 54B that are limited by the output voltage of the boost converter 72.

  FIG. 8 is a diagram illustrating the characteristics of the rotational speeds of the motors 54A and 54B according to the operation mode of the cam 62. In FIG. In FIG. 8, the horizontal axis represents time, and the vertical axis represents the rotational speed of the motors 54A and 54B.

  In FIG. 8, a characteristic A indicated by a solid line indicates the rotation speed of the motors 54A and 54B in the forward rotation drive mode. Further, characteristics B1 and B2 indicated by alternate long and short dash lines indicate the rotational speeds of the motors 54A and 54B in the swing drive mode. Here, the characteristic B1 indicates a characteristic when the intake valve 36 is lifted at a small operating angle, and the characteristic B2 indicates a characteristic when the intake valve 36 is lifted at a large operating angle. A characteristic C indicated by a solid line indicates a characteristic when the motors 54A and 54B are driven at a variable speed in the forward rotation drive mode.

  In the forward rotation drive mode, the motors 54A and 54B rotate in only one direction. In FIG. 8, the rotational speeds of the motors 54A and 54B in the forward rotation drive mode are positive values. In the oscillating drive mode, the motors 54A and 54B repeat normal rotation and reversal. Therefore, as shown in FIG. 8, the rotation speed indicated by the characteristics B1 and B2 is a characteristic in which a positive value and a negative value are repeated. .

  In the swing drive mode, when the intake valve 36 is driven at a small operating angle, the intake valve 36 needs to be opened and closed instantaneously in accordance with the rotation angle of the crankshaft 46, so that it is shown in FIG. Like the characteristic B1, the maximum value of the rotational speed of the motors 54A and 54B is relatively large. On the other hand, when the intake valve 36 is driven at a large operating angle, the intake valve 36 can be driven more slowly than at a small operating angle, so the rotational speeds of the motors 54A and 54B are reduced.

  In the present embodiment, the target voltage value of the boost converter 72 is determined based on the voltage value required by the motors 54A and 54B for each of the drive modes described above. Based on the target voltage value, the boosting operation of the boosting converter 72 is performed. Hereinafter, a method of determining the target voltage of boost converter 72 for each drive mode will be described.

  First, a case where the motors 54A and 54B are driven at a constant speed in the normal rotation drive mode will be described. In this case, the rotational speeds of the motors 54A and 54B are determined by the engine rotational speed of the internal combustion engine 10. Further, since the lift amount of the intake valve 36 reaches the maximum lift, when the engine speed is constant, the load applied to the motors 54A and 54B can be considered as a predetermined value set in advance. Therefore, the target output voltage of boost converter 72 is determined based on the rotational speeds of motors 54A and 54B determined from the rotational speed of internal combustion engine 10. As described with reference to FIG. 7, the target voltage is set such that the output voltage of boost converter 72 increases as the rotational speed of motors 54A and 54B increases.

  Next, a case where the motors 54A and 54B are driven at a constant speed in the swing drive mode will be described. Even in the case of swing drive, the rotational speeds of the motors 54A and 54B vary depending on the engine speed. Further, when the operating angle when lifting the intake valve 36 changes, the time during which the cam 62 pushes down the intake valve 36 changes, so the rotational speeds of the motors 54A and 54B also change depending on the operating angle. Accordingly, the rotational speeds of the motors 54A and 54B change according to the operating angle when the intake valve 36 lifts and the engine rotational speed. Furthermore, the loads on the motors 54A and 54B vary depending on the lift amount and operating angle of the intake valve 36. Therefore, in the swing drive mode, the target output voltage of boost converter 72 is calculated based on the rotational speed determined from the engine speed and the operating angle, and the load determined from the lift amount.

  Next, the case where the valve gears 48A and 48B are driven in the variable speed mode of the normal rotation drive mode will be described. In this case, as in the swing drive mode, the rotational speeds of the motors 54A and 54B change according to the engine speed and the operating angle. Further, as in the case of the forward rotation drive mode described above, since the intake valve 36 has reached the maximum lift, when the engine speed is constant, the load applied to the motors 54A and 54B is constant unless the operating angle changes. Can be considered. Therefore, in the variable speed mode, the target output voltage of the boost converter is calculated based on the rotational speed determined from the engine speed and the operating angle.

  Next, processing in the system of this embodiment will be described based on the flowcharts of FIGS. 9 and 10. FIG. 9 shows the process after switching to the swing drive mode, and FIG. 10 shows the process after switching to the variable speed mode of the normal rotation drive mode.

  First, processing in the swing drive mode will be described with reference to FIG. First, in step S1, switching to the swing drive mode is performed. In the next step S2, command values for the operating angle and the lift amount in the current operating state are acquired. In the next step S3, the maximum rotational speed when the camshafts 58A and 58B swing is calculated based on the current rotational speed of the crankshaft 46 and the command value of the operating angle.

  In the next step S4, the maximum load for driving the motors 54A and 54B is calculated based on the lift amount command value.

  In the next step S5, the target output voltage value of the boost converter 72 is calculated based on the maximum rotation speed and the maximum load calculated in steps S3 and S4. When the target output voltage value exceeds the capacity limit of the boost converter 72, the operating angle and the lift amount are corrected and the boost target value is recalculated.

  In the next step S6, the boost operation by the boost converter 72 is started based on the voltage value calculated in step S5. In the next step S7, after the boosting operation is completed, the swinging operation is executed within the range of the output voltage of the boosting converter 72. After step S7, the process ends (RETURN).

  Next, processing in the variable speed mode of the normal rotation drive mode will be described based on FIG. First, in step S11, switching to the variable speed mode is performed. In the next step S12, a command value for the operating angle in the current operating state is acquired. In the next step S13, the maximum rotational speed of the camshafts 58A and 58B is calculated based on the current rotational speed of the crankshaft 46 and the command value of the operating angle.

  In the next step S14, the target output voltage value of the boost converter 72 is calculated based on the maximum rotation speed calculated in step S13. At this time, the target output voltage value is calculated in consideration of a preset driving load of the motors 54A and 54B during the maximum lift. In the next step S15, the boost operation by the boost converter 72 is started based on the voltage value calculated in step S14.

  In the next step S16, after the boosting operation is completed, the swinging operation is executed within the range of the output voltage of the boosting converter 72. After step S16, the process ends (RETURN).

  As described above, according to the present embodiment, since the boosted voltage by the boost converter 72 is optimally controlled based on the operation pattern of the motors 54A and 54B, boosting can be performed within the minimum necessary range. Therefore, it is possible to improve the efficiency of the system. In addition, after boosting by boost converter 72 is completed, the operating angle and lift amount of intake valve 36 can be optimally controlled based on the boosted voltage.

Embodiment 2. FIG.
Next, the second embodiment of the present invention will be described with reference to FIG. 11 to FIG. 15. The description will focus on the differences from the first embodiment described above, and the same matters will be described. Simplify or omit.

[Description of system configuration]
FIG. 11 is a diagram for explaining a system configuration according to the second embodiment of the present invention. In the present embodiment, it is assumed that the internal combustion engine 10 is mounted on a vehicle (automobile) as a drive source. The system of the present embodiment shown in FIG. 11 has a temperature sensor 90 that detects the ambient temperature of the motors 54A and 54B (hereinafter referred to as “motor ambient temperature”), and the output of the internal combustion engine 10 is shifted and transmitted to the drive wheels of the vehicle. And an automatic transmission 92. Except for this point, the system of the present embodiment is the same as that of the first embodiment.

  As the motor ambient temperature, for example, when the cooling method of the motors 54A and 54B is air cooling, the air temperature in the engine room can be used, and when the cooling method is water cooling, the engine cooling water temperature is set. Can be used.

  The automatic transmission 92 may be a stepped transmission or a continuously variable transmission. Furthermore, the automatic transmission 92 may be a hybrid system that can function substantially as a transmission in combination with another drive source such as an electric motor.

  In the system of the present embodiment, in the light load region of the internal combustion engine 10, the cam 62 is driven in the swing drive mode and control is performed to reduce the operating angle of the intake valve 36. When the operating angle of the intake valve 36 is reduced in the light load range, the intake air amount is commensurate with the required load while maintaining the opening of the throttle valve 22 (hereinafter referred to as “throttle opening”) at a relatively large opening. The amount can be suppressed. For this reason, since the pump loss caused by reducing the throttle opening can be reduced, the fuel efficiency can be improved.

  FIG. 12 is a diagram showing the relationship between the lift curve of the intake valve 36 and the effective torque values of the motors 54A and 54B. The torque effective value is the square root of the root mean square value of the motor torque. In FIG. 12, the broken line is a graph when the operating angle of the intake valve 36 is 120 ° CA, and the solid line is a graph when the operating angle of the intake valve 36 is 60 ° CA. As can be seen from the lift curve of FIG. 12, the intake valve 36 needs to be opened and closed more rapidly as the operating angle is reduced. For this reason, it is necessary to increase the acceleration and deceleration of the motors 54A and 54B as the operating angle is reduced. Therefore, as shown in FIG. 12, the effective torque value of the motors 54A and 54B increases as the operating angle decreases. The amount of heat generated by the motors 54A and 54B is proportional to the square of the effective torque value. Therefore, the temperature of the motors 54A and 54B tends to increase as the operating angle decreases.

  FIG. 13 is a diagram showing the temperature rise of the motors 54A and 54B when the operating angle of the intake valve 36 and the throttle opening are changed while the torque of the internal combustion engine 10 is constant. As shown in FIG. 13, when the same engine torque is obtained, the throttle opening can be increased as the operating angle of the intake valve 36 is decreased. As a result, pump loss is reduced, and fuel efficiency can be improved. However, as described above, the temperature of the motors 54A and 54B is likely to rise as the operating angle of the intake valve 36 is reduced. For this reason, when the motor ambient temperature is high, the temperatures of the motors 54A and 54B may exceed the allowable temperature.

  FIG. 14 is a diagram showing the influence of the engine speed on the temperature rise of the motors 54A and 54B. As shown in FIG. 14, the temperature of the motors 54A and 54B tends to increase as the engine speed increases. This is because the higher the engine speed, the higher the rotational speed of the cam 62 and the higher the acceleration and deceleration of the motors 54A and 54B, and the higher the effective torque value and the heat generation amount of the motors 54A and 54B. It is.

  In view of the above circumstances, in this embodiment, when the temperature of the motors 54A and 54B may exceed the allowable temperature, the operating angle of the intake valve 36 is increased to increase the temperature of the motors 54A and 54B. It was decided to suppress the rise. At that time, the throttle opening is reduced as the operating angle of the intake valve 36 is increased so that the engine torque does not change as much as possible.

[Specific Processing in Second Embodiment]
FIG. 15 is a flowchart of a routine executed by the ECU 40 in the present embodiment in order to realize the above function. This routine is repeatedly executed every predetermined time.

  Further, in the present embodiment, the ECU 40 stores in advance a map or a calculation formula representing the relationship as shown in FIG. 12, that is, the relationship between the lift amount of the intake valve 36 and the effective torque values of the motors 54A and 54B. It shall be. Further, the ECU 40 stores in advance a map or a calculation formula representing the relationship as shown in FIGS. 13 and 14, that is, the relationship between the engine speed and the operating angle of the intake valve 36 and the temperature rise of the motors 54A and 54B. It is assumed that

  According to the routine shown in FIG. 15, first, the motor ambient temperature detected by the temperature sensor 90 is acquired (step 100). Next, it is determined whether or not the temperatures of the motors 54A and 54B may exceed the allowable temperature (step 102). Specifically, this processing is acquired in step 100 above with the motor temperature increase calculated by comparing the current engine speed and the operating angle of the intake valve 36 with the relationship of FIG. 13 and FIG. This is determined in view of the current motor ambient temperature.

  If it is determined in step 102 that the temperatures of the motors 54A and 54B are not likely to exceed the allowable temperature, it is not necessary to perform the following control, and thus the current processing cycle is terminated. On the other hand, when it is determined that the temperature of the motors 54A and 54B may exceed the allowable temperature, the motor torque effective value that can suppress the temperature of the motors 54A and 54B to the allowable temperature or less next. Is calculated (step 104). In this step 104, for example, an allowable heat generation amount can be calculated from the current motor ambient temperature, and an allowable motor torque effective value can be calculated based on the allowable heat generation amount.

  Subsequently, the operating angle and the throttle opening of the intake valve 36 are determined so that the temperatures of the motors 54A and 54B can be kept below the allowable temperature and the engine torque does not change as much as possible. (Step 106). Specifically, first, based on the allowable motor torque effective value calculated in step 104 and the current engine speed, the operating angle of the intake valve 36 is determined according to the relationship shown in FIG. . Next, the throttle opening is calculated by collating the determined operating angle with a relationship as shown in FIG.

  When the operating angle and throttle opening of the intake valve 36 are calculated in step 106, the operations of the motors 54A and 54B and the throttle valve 22 are controlled so that the operating angle and throttle opening are realized. (Step 108).

  According to the processing of the routine shown in FIG. 15 described above, when the temperature of the motors 54A and 54B may exceed the allowable temperature, the operating angle of the intake valve 36 is increased, and the amount of heat generated by the motors 54A and 54B. Can be suppressed. For this reason, it can prevent reliably that the temperature of motor 54A, 54B exceeds permissible temperature. For this reason, even when the ambient temperature of the motor is high, the motors 54A and 54B can be reliably protected.

  In addition, when the operating angle of the intake valve 36 is increased in the above case, the engine torque can be prevented from changing as much as possible by reducing the throttle opening. For this reason, it is possible to reliably prevent an increase in engine torque (or increase in vehicle speed) unintended by the driver, and good drivability can be obtained.

  Further, according to the routine processing shown in FIG. 15, the operating angle of the intake valve 36 can be maintained as large as possible within the range in which the temperatures of the motors 54A and 54B can be maintained below the allowable temperature. As a result, the pump loss of the internal combustion engine 10 can be reduced as much as possible while preventing overheating of the motors 54A and 54B, and excellent fuel efficiency performance can be obtained.

  In the second embodiment described above, the description has been made on the assumption that the cam 62 is driven in the swing drive mode. However, even when the cam 62 is driven in the variable speed mode of the forward rotation drive mode, The situation described above is the same. Therefore, the present embodiment can be similarly applied when the cam 62 is driven in the variable speed mode of the forward rotation drive mode.

  In the second embodiment described above, the ECU 40 executes the processing of steps 104 and 106, so that the “target operating angle determination means” in the first invention executes the processing of step 108. Thus, the “control means” in the first invention is realized. Further, when the ECU 40 executes the processing of the above steps 102 to 106, the “target valve opening characteristic correcting means” in the sixth invention and the “working angle correcting means” in the seventh invention become the steps 106 and By executing the process 108, the “throttle opening control means” in the seventh aspect of the present invention is realized.

Embodiment 3 FIG.
Next, the third embodiment of the present invention will be described with reference to FIG. 16. The description will focus on the differences from the second embodiment described above, and the same matters will be simplified or described. Omitted.

[Features of Embodiment 3]
In the second embodiment described above, when the temperatures of the motors 54A and 54B may exceed the allowable temperature, the operating angle of the intake valve 36 is increased to prevent overheating of the motors 54A and 54B. On the other hand, in the present embodiment, the overheating of the motors 54A and 54B is prevented by switching the driving mode of the cam 62 to the constant speed mode of the forward rotation driving mode.

  When the drive mode of the cam 62 is a constant speed mode of the normal rotation drive mode, the motors 54A and 54B rotate at a constant speed. That is, the motors 54A and 54B do not require acceleration / deceleration. For this reason, the driving torque of the motors 54A and 54B is not increased by the acceleration / deceleration torque, but only by the friction torque necessary for the rotation of the cam 62. Therefore, the effective torque values of the motors 54A and 54B are significantly reduced, and the amount of heat generation can be greatly reduced, so that the temperatures of the motors 54A and 54B can be reduced extremely effectively.

  When the drive mode of the cam 62 is a constant speed mode of the normal rotation drive mode, the operating angle of the intake valve 36 is determined by the profile of the cam 62. That is, when the drive mode of the cam 62 is switched from the rocking drive mode to the constant speed mode of the normal rotation drive mode, the operating angle is usually increased. Therefore, in this embodiment, when the forward drive mode is switched to the constant speed mode, the throttle opening is reduced so that the engine torque does not change as much as possible.

[Specific Processing in Embodiment 3]
FIG. 16 is a flowchart of a routine executed by the ECU 40 in the present embodiment in order to realize the above function. In FIG. 16, the same steps as those shown in FIG. 15 are denoted by the same reference numerals, and the description thereof is omitted or simplified. Further, this routine is executed when the cam 62 is driven in the swing drive mode.

  The routine shown in FIG. 16 is the same as the routine shown in FIG. 15 except that steps 104 to 108 in FIG. 15 are replaced with steps 110 to 114.

  According to the routine shown in FIG. 16, first, the motor ambient temperature is acquired (step 100), and then it is determined whether or not the temperatures of the motors 54A and 54B may exceed the allowable temperature (step 102). If it is determined in step 102 that the temperatures of the motors 54A and 54B may exceed the allowable temperature, the drive mode of the cam 62 is switched to the constant speed mode of the normal rotation drive mode (step 110).

  Subsequently, the throttle opening is calculated so that the engine torque does not change as much as possible (step 112). As described above, the operating angle in the constant speed mode of the forward rotation drive mode is determined by the profile of the cam 62. In step 112, the throttle opening is calculated based on the predetermined operating angle and the relationship as shown in FIG. When the throttle opening is calculated, the throttle valve 22 is subsequently controlled so that the throttle opening is realized (step 114). Thereby, the engine torque is kept constant before and after the switching of step 110.

  According to the processing of the routine shown in FIG. 16 described above, the drive mode of the cam 62 can be switched to the constant speed mode of the normal rotation drive mode when the temperatures of the motors 54A and 54B may exceed the allowable temperature. As a result, the effective torque values of the motors 54A and 54B can be greatly reduced, and the amount of heat generated can be greatly reduced, so that the temperatures of the motors 54A and 54B can be reduced extremely effectively. For this reason, even under severe conditions such as when the engine speed is high, it is possible to more reliably prevent the temperatures of the motors 54A and 54B from exceeding the allowable temperature.

  In the third embodiment described above, the “drive mode changing means” according to the eighth aspect of the present invention is implemented when the ECU 40 executes the processes of steps 100, 102, and 110 described above.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIG. 17. The description will focus on the differences from the second embodiment described above, and the same matters will be simplified or described. Omitted.

[Features of Embodiment 4]
In the present embodiment, when the temperatures of the motors 54A and 54B may exceed the allowable temperature, the motor 54A and 54B are prevented from being overheated by changing the gear ratio of the automatic transmission 92 to the high speed side. If the gear ratio is changed to the high speed side, the engine speed can be reduced even at the same vehicle speed. As described with reference to FIG. 14, the lower the engine speed, the smaller the amount of heat generated by the motors 54 </ b> A and 54 </ b> B. Therefore, it is possible to reliably prevent the motors 54A and 54B from exceeding the allowable temperature.

[Specific Processing in Embodiment 4]
FIG. 17 is a flowchart of a routine executed by the ECU 40 in the present embodiment in order to realize the above function. In FIG. 17, the same steps as those shown in FIG. 15 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  The routine shown in FIG. 17 is the same as the routine shown in FIG. 15 except that steps 104 to 108 in FIG.

  According to the routine shown in FIG. 17, first, the motor ambient temperature is acquired (step 100), and then it is determined whether or not the temperatures of the motors 54A and 54B may exceed the allowable temperature (step 102). If it is determined in step 102 that the temperatures of the motors 54A and 54B may exceed the allowable temperature, the gear ratio of the automatic transmission 92 is changed to the high speed side (step 116). That is, the shift of the automatic transmission 92 is executed so that the speed ratio or gear position is higher than the current speed.

  According to the routine processing shown in FIG. 17, when the temperature of the motors 54A and 54B may exceed the allowable temperature, the speed ratio of the automatic transmission 92 is changed to the high speed side to reduce the engine speed. Can be made. Thereby, since the emitted-heat amount of motor 54A, 54B can be reduced, the temperature of motor 54A, 54B can be reduced effectively.

  In the fourth embodiment, the automatic transmission 92 corresponds to the “transmission” in the ninth aspect of the invention. Further, the “engine speed suppressing means” according to the ninth aspect of the present invention is implemented by the ECU 40 executing the routine shown in FIG.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a schematic diagram which shows the periphery structure of an intake valve and a valve operating apparatus. It is a schematic diagram which shows a mode that an intake valve is driven with a cam. It is a schematic diagram which shows the relationship between the engine speed of an internal combustion engine, output torque, and the drive mode of a cam. It is a schematic diagram which shows two types of cams provided in the camshaft in detail. It is a schematic diagram which shows the drive converter which drives the motor of a valve operating apparatus, and the step-up converter which supplies electric power to a drive system. It is a characteristic view which shows the relationship between the output voltage of a boost converter, the rotation speed of a motor, and load. It is a figure which shows the characteristic of the rotational speed of the motor according to the operation mode of a cam. It is a flowchart which shows a process in case driving | running is performed by rocking | fluctuation drive mode. It is a flowchart which shows a process in case driving | running is performed by the variable speed mode of normal rotation drive mode. It is a figure for demonstrating the system configuration | structure of Embodiment 2 of this invention. It is a figure which shows the relationship between the lift curve of an intake valve, and the torque effective value of a motor. It is a figure which shows the temperature rise of a motor at the time of changing the operating angle and throttle opening of an intake valve by making engine torque constant. It is a figure which shows the influence of the engine speed with respect to the temperature rise of a motor. It is a flowchart of the routine performed in Embodiment 2 of this invention. It is a flowchart of the routine performed in Embodiment 3 of the present invention. It is a flowchart of the routine performed in Embodiment 4 of this invention.

Explanation of symbols

10 Internal combustion engine 36 Intake valve 38 Exhaust valve 40 ECU
48A, 48B Valve train 54A, 54B Motor 58A, 58B Camshaft 72 Boost converter

Claims (9)

A valve driving means for opening and closing a valve body included in each cylinder by a motor;
A target operating angle determining means for determining a target operating angle when driving the valve body in accordance with a limitation of a driving load of the motor or a rotational speed of the motor;
Control means for driving the motor based on the target operating angle;
A control apparatus for an internal combustion engine, comprising: A booster circuit for boosting a voltage supplied to the motor;
Target voltage setting means for setting a target value of a voltage supplied from the booster circuit to the motor according to the driving load of the motor or the rotational speed of the motor;
Boost control means for controlling the boost operation of the boost circuit based on the target value;
The control apparatus for an internal combustion engine according to claim 1, further comprising:   3. The target operating angle determining means determines the target operating angle based on a limit of a driving load of the motor or a rotational speed of the motor and a limit value of the capacity of the booster circuit. The internal combustion engine control device described.   The target working angle determining means determines the target working angle according to a limit of a driving load of the motor or a rotational speed of the motor determined from an output voltage value of the booster circuit. 3. The control device for an internal combustion engine according to 3. The valve drive means drives a camshaft for driving the valve body in a swing drive mode,
A lift amount determining means for determining a target lift amount when driving the valve body in accordance with a limitation of a driving load of the motor;
The control device for an internal combustion engine according to any one of claims 1 to 4, wherein the control means drives the motor based on the target operating angle and the target lift amount. A valve driving means for opening and closing a valve body included in each cylinder by a motor;
Target valve opening characteristic correcting means for correcting the target valve opening characteristic of the valve body so that the temperature of the motor is equal to or lower than the allowable temperature when the temperature of the motor may exceed the allowable temperature;
Control means for driving the motor based on the corrected target valve opening characteristic;
A control apparatus for an internal combustion engine, comprising: The target valve opening characteristic correcting means includes a working angle correcting means for increasing a target working angle of the valve body when the temperature of the motor may exceed an allowable temperature.
A throttle valve provided in an intake passage of the internal combustion engine;
Throttle opening control means for reducing the opening of the throttle valve so that the engine torque does not change when the target operating angle is increased by the operating angle correction means;
The control apparatus for an internal combustion engine according to claim 6, further comprising:   When the camshaft for driving the valve element is driven in the swing drive mode, the target valve opening characteristic correction means may be configured to detect the cam when the temperature of the motor may exceed an allowable temperature. 8. The control apparatus for an internal combustion engine according to claim 6, further comprising drive mode changing means for changing the drive mode of the shaft to a normal rotation drive mode. Valve drive means for opening and closing a valve body included in each cylinder of the internal combustion engine by a motor;
A transmission provided between the internal combustion engine and a drive shaft of the vehicle;
An engine speed suppression means for reducing the engine speed by changing the gear ratio of the transmission to a high speed side when the temperature of the motor may exceed an allowable temperature;
A control apparatus for an internal combustion engine, comprising:

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