JP2004183526A - Control device for internal combustion engine having variable valve train - Google Patents

Abstract

Provided is a technique for suppressing deterioration of control performance of an internal combustion engine when an abnormality occurs in a measurement system of a variable valve mechanism.
The present invention is a control device for controlling an internal combustion engine. The present control device is a valve control system that controls a valve adjustment mechanism capable of arbitrarily adjusting a working angle, which is at least a valve opening period of a valve included in the internal combustion engine, with a predetermined width. And a valve measurement system abnormality detection unit for detecting. This valve control system is characterized in that it can be switched to a control mode in which the operating angle is set to one of a plurality of predetermined angles in response to detection of an abnormality.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fail-safe process performed when an abnormality occurs in a control system of a variable valve mechanism.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a technique for changing the opening / closing characteristics of an intake / exhaust valve (hereinafter, referred to as valve opening / closing characteristics) according to the operating state of an internal combustion engine has been known. This technique can efficiently operate an internal combustion engine in various situations by changing valve opening / closing characteristics such as valve opening / closing timing, valve opening period (so-called operating angle), and valve lift. For example, if the valve opening period is lengthened, high rotation and high output can be obtained, and if the valve opening period is shortened, low / medium speed torque can be increased.
[0003]
However, the variable valve mechanism for changing the valve opening / closing characteristics may also be abnormal.
[0004]
The following is disclosed as a technique relating to processing for an abnormality of the variable valve mechanism (hereinafter, referred to as fail-safe processing). Patent Literature 1 discloses a fail-safe process for fixing a variable valve mechanism at a position where the operating angle of the variable valve mechanism is the smallest. Patent Literature 2 discloses a fail-safe process for preventing an imbalance that occurs when only one of the mechanisms causes an abnormality in a V-type engine or a horizontally opposed engine having two variable valve mechanisms. . Patent Literature 3 discloses a fail-safe process that stops the operation of the variable valve mechanism and limits the engine speed. Patent Literature 4 discloses fail-safe processing such as increasing the fuel supply amount or prohibiting learning. As described above, conventionally, the fail-safe processing is performed on the assumption that the variable valve mechanism is stopped, regardless of whether the abnormality is in the measurement system or the drive system. Had been done.
[Patent Document 1] Japanese Patent No. 2817055
[Patent Document 2] Japanese Patent No. 2862973
[Patent Document 3] JP-A-63-1727
[Patent Document 4] JP-A-13-254637
[0005]
[Problems to be solved by the invention]
As described above, in the conventional fail-safe processing, even if the drive system of the variable valve operating function is normal, the entire variable valve operating mechanism has to be stopped only by the abnormality of the measurement system of the variable valve operating function. . As a result, the control performance of the internal combustion engine may be significantly deteriorated only by the abnormality of the measurement system of the variable valve operating function.
[0006]
The present invention has been made to solve the above-described problem, and in an internal combustion engine having a variable valve mechanism, suppresses deterioration of control performance of the internal combustion engine when an abnormality occurs in a measurement system of the variable valve mechanism. The purpose is to provide the technology for doing.
[0007]
[Means for Solving the Problems and Their Functions and Effects]
In order to solve the above problems, the present invention is a control device for controlling an internal combustion engine,
A valve control system for controlling a valve adjustment mechanism capable of arbitrarily adjusting a working angle, which is at least a valve opening period of a valve of the internal combustion engine, with a predetermined width;
A valve measurement system abnormality detection unit that detects an abnormality of the measurement system that the valve control system has,
With
The valve control system can switch to a control mode in which the operating angle is set to one of a plurality of predetermined angles in response to the detection of the abnormality.
[0008]
According to the control device of the present invention, it is possible to switch to the control mode in which the operating angle is set to only a plurality of predetermined angles according to the determination that the measurement system included in the valve control system is abnormal. The control performance of the internal combustion engine can be suppressed from deteriorating as compared with the fail-safe processing method in which the variable valve mechanism is stopped when an abnormality occurs in the measurement system of the mechanism.
[0009]
In the above control device,
The control device has an idling mode that is a control mode for idling, and a traveling mode that is a control mode for traveling,
The valve control system, when the abnormality is detected, according to the switching of the control mode, any one of a plurality of angles including the working angle for the idling mode and the working angle for the traveling mode Crab control to set the working angle,
It is preferable that the operating angle for the traveling mode is a maximum value of the predetermined width.
[0010]
With this configuration, a large operating angle can be obtained in the traveling mode in which a large output may be desired, so that the evacuation operation can be performed safely.
[0011]
In the above control device,
A throttle valve control system for controlling a throttle valve that adjusts an intake flow rate flowing into a combustion chamber of the internal combustion engine,
The valve control system, when the abnormality is detected, according to the switching of the control mode, when the control device is performing the control in the traveling mode, the valve operating angle is set to the maximum value, the When the control device is performing control in the idling mode, the working angle is set to an intermediate value smaller by a predetermined value than the maximum value,
The throttle valve control system, when the abnormality is detected, when the control device is performing control in the traveling mode, the intake air for traveling on the assumption that the operating angle is set to the maximum value. Preferably, the flow rate is controlled, and when the control device is performing control in the idling mode, the intake flow rate for idling is controlled on the assumption that the operating angle is set to the intermediate value.
[0012]
This makes it possible to reduce a sudden change in the characteristics of the intake system of the internal combustion engine due to the switching of the operating angle.
[0013]
In the above control device,
The valve control system can set the operating angle to the maximum value by outputting a control output for increasing the operating angle to the valve adjusting mechanism for a first time that is predetermined. On the other hand, it is possible to set the operating angle to the intermediate value by outputting a control output for reducing the operating angle to the valve adjusting mechanism for a second time that is predetermined.
The first time is a time longer than the time during which the operating angle can be changed from the minimum state to the maximum state by a certain amount,
It is preferable that the second time is a time shorter than the time during which the operating angle can be changed from the maximum state to the minimum state by a certain amount.
[0014]
In this case, the present invention can be easily applied simply by adding a function of measuring the output time of the predetermined control output.
[0015]
In the above control device,
The valve control system, when the abnormality is detected, according to the switching of the control mode, when the control device is performing the control in the traveling mode, the valve operating angle is set to the maximum value, the When the control device is performing control in the idling mode, the working angle is set to a minimum value obtained by the valve adjustment mechanism,
The throttle valve control system, when the abnormality is detected, when the control device is performing control in the traveling mode, the intake air for traveling on the assumption that the operating angle is set to the maximum value. The flow rate may be controlled, and when the control device is performing control in the idling mode, the intake flow rate for idling may be controlled on the assumption that the operating angle is set to the minimum value.
[0016]
In the above control device,
The valve adjustment mechanism,
A camshaft having a three-dimensional cam whose shape is set so that the working angle can be changed according to the displacement in the axial direction,
An electric motor that displaces the camshaft in the axial direction according to a control output from the valve control system;
A valve spring for biasing the valve in the valve closing direction;
With
The camshaft may be configured to open the valve against the valve spring by pressing the valve according to the rotation of the camshaft.
[0017]
In many cases, a motor-driven actuator is more reliable than a hydraulic actuator or other actuators, so when using a variable valve mechanism that uses a motor-driven actuator, the fail-safe processing according to the present invention can be particularly effective. High in nature.
[0018]
Note that the present invention can be realized in various aspects. For example, a control device or a control method of an internal combustion engine, a computer program for realizing the functions of the control device or the control method, and a recording of the computer program Recording medium, a data signal including the computer program and embodied in a carrier wave, and the like.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described in the following order based on examples.
A. Device configuration:
B. Fail-safe processing in the first embodiment:
C. Fail-safe processing in the second embodiment:
D. Fail-safe processing in the third embodiment:
E. FIG. Modification:
[0020]
A. Device configuration:
FIG. 1 shows a configuration of a control device as one embodiment of the present invention. This control device is configured as a device that controls a gasoline engine 100 mounted on a vehicle. Engine 100 draws a mixture of gasoline and air from intake pipe 110, ignites the mixture with a spark plug 102, burns the mixture, and discharges exhaust gas from exhaust pipe 120 to the outside. The intake pipe 110 is provided with a throttle valve 111 for adjusting the flow rate of the air-fuel mixture during traveling and a bypass pipe 130 serving as a flow path of the air-fuel mixture during idling. The bypass pipe 130 includes an idling control valve 130V for adjusting the amount of the air-fuel mixture during idling. The exhaust pipe 120 is provided with a catalyst 124 for removing harmful components in the exhaust gas.
[0021]
The intake and exhaust strokes of the engine 100 are switched according to the open / close state of the intake valve 153 and the exhaust valve 122. The intake valve 153 is provided with a variable valve mechanism 200 for adjusting the opening / closing timing. The variable valve mechanism 200 can change the magnitude of the lift amount of the intake valve 153 (hereinafter, referred to as a valve lift amount) and the valve opening period (so-called operating angle) of the valve. As such a variable valve mechanism, for example, a mechanism described in JP-A-2002-161664 disclosed by the present applicant can be used. In addition, not only the magnitude and operating angle of the lift amount of the intake valve 153, but also the position of the valve opening period (also referred to as “phase of the valve opening period”) can be changed simultaneously or independently. good.
[0022]
The operation of the engine 100 is controlled by an electronic control unit 10 (hereinafter, referred to as an ECU). The ECU 10 is configured as a microcomputer including a CPU, a RAM, and a ROM inside. The ECU 10 is supplied with signals from various sensors. These sensors include a knock sensor 104 for detecting occurrence of knocking, a water temperature sensor 106 for detecting engine water temperature, a rotation speed sensor 108 for detecting engine speed, and an accelerator sensor 109 for detecting accelerator opening. And is included.
[0023]
An unillustrated memory of the ECU 10 stores an operating angle map 12 for setting the operating angle of the intake valve 153 and an intake flow rate map 16 for setting the amount of air-fuel mixture flowing into the combustion chamber. These maps are used to set the valve lift amount and the amount of air-fuel mixture flowing into the combustion chamber according to the rotation speed of the engine 100, the accelerator opening, the engine water temperature, and the like. When the engine 100 is of a type that injects fuel in the combustion chamber, the intake flow rate map 16 is used to set the amount of air flowing into the combustion chamber.
[0024]
FIG. 2 is an explanatory diagram showing the structure of the variable valve mechanism 200. The variable valve mechanism 200 includes a camshaft 210 that drives the opening and closing of the intake valve 153 by rotation, an actuator 220 that drives the camshaft 210 in the axial direction, and an attachment 215 that connects the camshaft 210 and the actuator 220. .
[0025]
The actuator 220 includes an output shaft 226, an electric motor 221 for rotating the output shaft 226, a rotary encoder 222 for measuring a rotation angle of the output shaft 226, and a slide member that moves in the direction of the cam shaft according to the rotation of the output shaft 226. 223, a bearing 225 that rotatably supports the attachment 215 with respect to the slide member 223, and mechanical stoppers 228a, 228b, and 229.
[0026]
Screws are formed on the inner periphery of the slide member 223 and the outer periphery of the output shaft 226, respectively. These screws convert the rotation of the output shaft 226 into movement of the slide member 223 in the direction of the cam shaft. A steel ball 224 for reducing frictional resistance is fitted between the two.
[0027]
The mechanical stoppers 228a, 228b, 229 are provided to limit the axial movement range of the camshaft 210 to a predetermined width. This restriction is realized by restricting the movement range of the member 229 between the end of the bolt 228a and the end of the bolt 228b. Thereby, the maximum working angle obtained by the variable valve mechanism 200 when the member 229 bottoms at the end of the bolt 228a is obtained, and when the member 229 bottoms at the end of the bolt 228b, This is the minimum working angle that can be obtained. The maximum working angle can be adjusted by operating the bolt 228a, and the minimum working angle can be adjusted by operating the bolt 228b.
[0028]
FIG. 3 is a perspective view of the cam 211 of the camshaft 210 as viewed from the intake valve 153 side. As can be seen from FIG. 3, the shape of the cam 211 is set so that the operating angle can be changed according to the displacement of the cam shaft 210 in the axial direction. The camshaft 210 is displaced in the axial direction according to the displacement of the slide member 223 via the attachment 215.
[0029]
The rotation of the cam 211 is performed by a timing pulley (not shown) provided at the other end of the cam shaft 210. The timing belt wound around the timing pulley is connected to a crankshaft (not shown). When the cam 211 rotates, a force is applied to the valve lifter 152 via the cam follower 156 that swings according to the direction of the contact surface of the cam 211. The end of the intake valve 153 is connected to the valve lifter 152.
[0030]
The valve lifter 152 is urged by a valve spring 151 so that the intake valve 153 is closed. On the other hand, the cam 211 pushes the valve lifter 152 in a direction to open the intake valve 153 by the rotation of the cam shaft 210. The movement amount of the intake valve 153 at this time is the valve lift amount.
[0031]
FIG. 4 is an explanatory diagram showing the relationship between the crank angle and the valve lift. As can be seen from FIG. 4, while the valve lift of the exhaust valve 122 has a fixed profile, the valve lift of the intake valve 153 has a variable profile. The profile of the intake valve 153 changes continuously according to the axial position of the camshaft 210 (FIG. 2).
[0032]
Specifically, the profile at the time of the minimum lift is obtained when the camshaft 210 is closest to the actuator 220 side, and the profile at the time of the maximum lift is obtained when the camshaft 210 is farthest from the actuator 220. Further, in this embodiment, the operating angle also changes according to the position of the camshaft 210 in the axial direction. Specifically, as can be seen from FIG. 4, the operating angle becomes minimum at the time of the minimum lift, and the operating angle becomes maximum at the time of the maximum lift.
[0033]
The axial position of the camshaft 210 is determined by the rotation angle of the output shaft 226 (FIG. 2) of the electric motor 221. This rotation angle can be measured by the rotary encoder 222 that measures the rotation angle of the output shaft 226. The measurement of the angle by the rotary encoder 222 is performed by the ECU 10 (FIG. 1) by counting the pulses output by the output shaft 226 at each predetermined rotation angle. Thus, the ECU 10 can specify the profile of the valve lift of the intake valve 153.
[0034]
The ECU 10 can control the valve lift profile of the intake valve 153 according to the rotation speed and load of the engine 100, the engine coolant temperature, and the like, while referring to the operating angle map 12. The working angle map 12 stores the rotation angle of the output shaft 226 as a target value of the valve lift amount. This control is performed as follows.
(1) The pulse from the rotary encoder 222 is counted and the rotation angle of the output shaft 226 is measured.
(2) The measured angle which is the rotation angle of the output shaft 226 is compared with the target angle which is the rotation angle of the output shaft 226 as the target value read from the working angle map 12.
(3) In accordance with the difference between the target angle and the measurement angle, the ECU 10 sends a control output to a motor drive unit 227 (not shown) of the motor 221.
(4) The motor drive unit 227 changes the voltage applied to the motor 221 according to the control output from the ECU 10.
As described above, in the present embodiment, a feedback control system using the angle measured by the rotary encoder 222 as a control input is configured.
[0035]
On the other hand, the ECU 10 adjusts the flow rate of the air-fuel mixture to the combustion chamber on the assumption that the control of the valve lift is normal. Adjustment of the flow rate of the air-fuel mixture is performed by operating the throttle valve 111 and the idling control valve 130V. These valve operations are performed by referring to the intake flow rate map 16 according to the rotation speed of the engine 100, the accelerator opening, the engine water temperature, and the like.
[0036]
The term “throttle valve control system” in the claims means a control system that controls the throttle valve 111 and the idling control valve 130V. Further, the ECU 10 functions as a “valve control system” or a “throttle valve control system” in the claims.
[0037]
As described above, the internal combustion engine of the present embodiment is configured so that control suitable for the operating state can be performed by controlling the valve operating angle and the intake air flow rate. In this specification, the terms of setting, adjusting, and switching of the valve lift amount mean setting, adjusting, and switching of the profile of the valve lift, and setting, adjusting, and switching of the operating angle. I have.
[0038]
B. Fail-safe processing in the first embodiment:
FIG. 5 is a flowchart illustrating the flow of the fail-safe process in the first embodiment. This fail-safe process is a process on the assumption that the rotary encoder 222 does not function properly. If the rotary encoder 222 does not function properly, the axial position of the camshaft 210 (FIG. 2) cannot be measured. As a result, feedback control for adjusting the operating angle becomes impossible. To such a situation, the fail-safe processing of the first embodiment responds as follows.
[0039]
In step S110, ECU 10 (FIG. 1) detects an abnormality of rotary encoder 222. The detection of the abnormality is performed, for example, when a pulse is not continuously input from the rotary encoder 222 for a predetermined time. The process proceeds to step S200 until an abnormality is detected. The processing in step S200 will be described later. On the other hand, if an abnormality is detected, the process proceeds to step S120.
[0040]
In step S120, the ECU 10 determines whether the control mode of the internal combustion engine is the idling mode. The idling mode is a control mode in which the engine speed is reduced and fuel efficiency is improved as much as possible within a range where engine speed and engine speed do not become unstable. In this control mode, the throttle valve 111 is closed, and the air-fuel mixture passes through the bypass pipe 130 having the idling control valve 130V. The ECU 10 controls the rotation speed of the internal combustion engine by operating the idling control valve 130V while measuring the rotation speed of the internal combustion engine.
[0041]
If the control mode of the internal combustion engine is the idling mode, the process proceeds to step S130. If the control mode of the internal combustion engine is the running mode, the process proceeds to step S140 described below. The running mode means a control mode other than the idling mode.
[0042]
In step S130, the ECU 10 performs a minimum lift process. The minimum lift process is a process in which the motor 221 is driven to displace the camshaft 210 (FIG. 2) until the camshaft 210 bottoms toward the motor 221. The reason why the minimum lift process is performed is to reduce the pump loss caused by the negative pressure generated in the intake system to improve fuel efficiency. The minimum lift process is performed as follows.
[0043]
FIG. 6 is a flowchart showing the flow of the minimum lift process performed in the fail-safe process. In step S131, the ECU 10 issues a minimum lift instruction. The minimum lift instruction is an operation of outputting a predetermined control output for reducing the valve lift amount to the motor drive unit 227. The predetermined control output is output by, for example, fixing the target angle of the output shaft 226 to a value at which the valve lift amount becomes the minimum and simulating the measured angle of the output shaft 226 to a value at which the valve lift amount becomes the maximum. Can be.
[0044]
In step S132, the elapsed time counter (not shown) of the ECU 10 counts up. In step S133, it is determined whether or not the count of the elapsed time counter is larger than a predetermined value A. If the count is smaller than the predetermined value A, the process returns to step S131. If the count is larger than the predetermined value A, the process ends. The predetermined value A is set such that the elapsed time is longer by a predetermined time than the time during which the valve lift can be changed from the maximum state to the minimum state. This ensures that the camshaft 210 bottoms out at a position where the valve lift is minimized.
[0045]
Specifically, for example, when the control system for controlling the valve lift is operating with a clock having a cycle of 0.001 seconds, the predetermined time during which the valve lift can be changed from the maximum state to the minimum state is zero. Suppose that the constant time is 0.02 seconds. In this case, the predetermined value A is set to 119, and the control output is stopped when the count reaches 120 times.
[0046]
On the other hand, when the control mode of the internal combustion engine is the running mode (the control mode other than the idling mode) (FIG. 5), the maximum lift process is performed. The maximum lift process is a process in which the motor 221 is driven to displace the camshaft 210 (FIG. 2) until the camshaft 210 bottoms out on the opposite side to the motor 221. The reason why the maximum lift process is performed is to increase the valve lift as much as possible so that the evacuation operation can be performed safely.
[0047]
FIG. 7 is a flowchart illustrating the flow of the maximum lift process performed in the fail-safe process. In steps S141 to S143, the same processing as in steps S131 to S133 described above is performed. However, the direction in which the camshaft 210 is displaced is opposite to the minimum lift process. The threshold value of the count of the elapsed time counter is changed from A to B. This is because the time required for the maximum lift processing is longer than the time required for the minimum lift processing. The reason why the time required for the maximum lift process becomes longer is that the moving speed of the camshaft 210 is slowed by the component Faxis of the reaction force Fn of the valve spring 151 (FIG. 2) in the direction of the camshaft 210.
[0048]
In step S144, the ECU 10 sends a holding current output command to the motor driving unit 227 (FIG. 2). The holding current output command is a command for causing the motor drive unit 227 to pass a holding current for holding the position of the camshaft 210. The holding current is caused to flow through the motor drive unit 227 in order to prevent the camshaft 210 from being pushed back to the motor 221 by the force Faxis caused by the reaction force of the valve spring 151. Upon completion of the maximum lift process, the process proceeds to step S150 (FIG. 5).
[0049]
In step S150 (FIG. 5), the ECU 10 sets a failsafe processing execution flag. The fail-safe processing execution flag is a flag for executing the fail-safe processing in the next step S200. In step S200, an intake flow rate control process is performed.
[0050]
FIG. 8 is a flowchart illustrating the flow of the intake air flow control process according to the first embodiment of the present invention. The intake flow rate control process is a process for controlling the flow rate of the air-fuel mixture flowing into the combustion chamber of the engine 100 (FIG. 1). The intake flow control process is performed using an intake flow map 16 included in the ECU 10.
[0051]
FIG. 9 is an explanatory diagram showing the contents of the intake flow rate map 16 used in the intake flow rate control processing of the first embodiment. The intake flow rate map 16 is a map used for controlling the throttle valve 111 and the idling control valve 130V.
[0052]
The intake flow map 16 includes an IDL map 16NI used for controlling the idling control valve 130V during idling, an ND map 16ND used for controlling the throttle valve 111 when the variable valve mechanism 200 is normal, An FD map 16FD used for controlling the throttle valve 111 when the variable valve mechanism 200 is abnormal is provided.
[0053]
During idling, the same IDL map 16NI is used regardless of whether the variable valve mechanism 200 is normal or abnormal. This is because, during idling, the valve lift can be set to the minimum value regardless of whether the variable valve mechanism 200 is normal or abnormal as described above.
[0054]
In step S210, the ECU 10 inputs the accelerator opening. The accelerator opening is the angle (deg) of the accelerator tilted by depressing. In step S220, the ECU 10 determines whether or not the set fail-safe processing execution flag is “ON”. When the fail-safe processing execution flag is “OFF”, that is, when the variable valve mechanism 200 is normal, the following processing is performed.
[0055]
In step S230, the ECU 10 performs an accelerator opening nonlinear conversion process. The accelerator opening nonlinear conversion process is a process of calculating a nonlinear throttle opening in accordance with the input accelerator opening. The non-linear throttle opening is a value serving as a reference value of the throttle opening. The calculation of the nonlinear throttle opening is performed using a map (FIG. 10) storing the accelerator opening and the nonlinear throttle opening. This map is stored in an ND map 16ND (FIG. 9) used for controlling the throttle valve 111 when the variable valve mechanism 200 is normal. The throttle opening is calculated from the nonlinear throttle opening in step S240 as follows.
[0056]
FIG. 11 is a flowchart illustrating the flow of the throttle opening calculation process in the first embodiment. In step S241, the ECU 10 calculates a target air amount. The calculation of the target air amount is performed according to the non-linear throttle opening and the vehicle speed. In step S242, the ECU 10 calculates a target valve lift amount that is a target value of the valve lift amount. The target valve lift amount is calculated according to the target air amount and the engine speed. The target valve lift amount is used as a target value of the normally operating variable valve mechanism 200.
[0057]
In step S243, the ECU 10 calculates the throttle opening. The throttle opening is calculated according to the target air amount and the engine speed similarly to the target valve lift amount. As described above, when the valve lift system is normal, the internal combustion engine is operated with the valve lift amount and the throttle opening suitable for the accelerator opening and the vehicle speed.
[0058]
On the other hand, if the set fail-safe process execution flag is “ON”, the process proceeds to step S250 to perform the fail-safe process corresponding to the failure of the variable valve mechanism 200 (FIG. 8).
[0059]
In step S250, the ECU 10 performs a failsafe mode / accelerator opening non-linear conversion process. This conversion process is a process of directly calculating the throttle opening in accordance with the input accelerator opening. This calculation process is performed using the FD map 16FD used for controlling the throttle valve 111 when the variable valve mechanism 200 is abnormal. The FD map 16FD is a map on the assumption that the valve lift is set to the maximum value.
[0060]
As described above, in the first embodiment, in the case where an abnormality occurs in the measurement system of the variable valve mechanism 200, the valve lift amount is increased at the time of traveling to enable safe retreat traveling, and at the time of idling, the valve lift amount is increased. Can be minimized to suppress fuel consumption deterioration. As a result, it is possible to suppress deterioration of control performance of the internal combustion engine when an abnormality occurs in the measurement system of the variable valve mechanism 200.
[0061]
C. Fail-safe processing in the second embodiment:
FIG. 12 is a flowchart illustrating the flow of the fail-safe process according to the second embodiment. This fail-safe processing differs from the fail-safe processing of the first embodiment (FIG. 5) in the processing at the time of idling. Specifically, in the first embodiment, the minimum lift processing for minimizing the valve lift amount is performed at the time of idling, but in the present embodiment, the intermediate lift processing for setting the valve lift amount to an intermediate position is performed. Be done.
[0062]
The reason why the valve lift amount is set to the intermediate position during idling is to alleviate a sudden change in the characteristics of the intake system of the engine 100 due to switching of the control mode between the running mode and the idling mode. In particular, in the engine 100 in which the adjustment range of the valve lift amount is large, the discontinuous switching from the maximum lift to the minimum lift involves a rapid change in the characteristics of the intake system. In this embodiment, the valve lift during idling is set to a predetermined intermediate position from the minimum position to the maximum side in order to reduce such a sudden change in characteristics.
[0063]
The setting of the predetermined intermediate position can be determined, for example, as a trade-off between a rapid change in output due to a sudden change in characteristics of the intake system and fuel efficiency after switching. The setting of the valve lift amount to a predetermined intermediate position is performed in step S130a. In step S130a, an intermediate lift process is performed.
[0064]
FIG. 13 is a flowchart illustrating the flow of the intermediate lift process performed in the fail-safe process. In steps S131a to S133a, the same processing as in steps S141 to S143 described above is performed. Thereby, the camshaft 210 once bottoms on the actuator 220 side, and the axial position of the camshaft 210 becomes clear. When these processes are completed, the counter is cleared.
[0065]
In steps S134a to S136a, the ECU 10 issues a lift amount return instruction until the counter exceeds the value of C. The lift amount return instruction is an operation of outputting a predetermined control output for reducing the valve lift amount to the electric motor drive unit 227, and may be, for example, the same instruction as the minimum lift instruction. As a result, the valve lift is set at a predetermined intermediate position between the maximum and the minimum. Thereafter, a holding current for holding the position of the camshaft 210 is passed to the electric motor drive unit 227 (step S137a), and the map used for intake air flow control indicates that the valve lift amount is set to the intermediate position. Switch to the assumed map.
[0066]
FIG. 14 is an explanatory diagram showing the contents of the intake flow rate map 16a used in the second embodiment. The intake flow rate map 16a differs from the intake flow rate map 16 of the first embodiment in that the intake flow rate map 16a includes an FID map 16FI which is a map used for controlling the idling control valve 130V in idling at the time of abnormality. The FID map 16FI is a map on the premise that the valve lift is set at the intermediate position as described above.
[0067]
It should be noted that once the valve lift amount is set to the intermediate position or the maximum position once the fail-safe process is performed, the camshaft 210 is controlled to reciprocate between the intermediate position and the maximum position.
[0068]
As described above, in the second embodiment, since the valve lift can be set at the predetermined intermediate position, the control that balances the rapid change of the output with the switching of the valve lift and the fuel efficiency at the time of idling is achieved. There is an advantage that the system can be configured.
[0069]
D. Fail-safe processing in the third embodiment:
FIG. 15 is a flowchart illustrating the flow of the fail-safe process according to the third embodiment. This fail-safe process differs from the fail-safe processes of the above-described embodiments in that three valve lift amounts can be set. Specifically, for example, a minimum lift position set when idling, an intermediate lift position set when the accelerator opening is relatively small, and a maximum lift position set when the accelerator opening is relatively large. The valve lift can be set in three places.
[0070]
The reason why the valve lift amount can be set at three positions is to alleviate a sudden change in the characteristics of the intake system of the engine 100 due to the switching of the control mode and to enable idling at the minimum lift position.
[0071]
FIG. 16 is an explanatory diagram showing the contents of the intake flow rate map 16b used in the third embodiment. The intake flow rate map 16b is different from the FID map 16FI, which is a map used for controlling the idling control valve 130V in idling at the time of abnormality, with an FLD map 16FLD used at the time of low output at the time of abnormality. It is different from the flow map 16a.
[0072]
The IDL map 16FI is deleted because idling is performed at the minimum lift position, and the normal IDL map 16NI can be used as it is. The FLD map 16FLD is a map used when the accelerator opening is smaller than a predetermined angle.
[0073]
In the present embodiment, the following fail-safe processing can be performed using the intake flow rate map 16b.
(1) With the accelerator off, control of the internal combustion engine using the IDL map 16NI is performed at the minimum valve lift position.
(2) When the accelerator is turned on and the accelerator opening is smaller than the predetermined angle, the control of the internal combustion engine using the FLD map 16FLD is performed at the intermediate valve lift position.
(3) When the accelerator is turned on and the accelerator opening is equal to or larger than a predetermined angle, the internal combustion engine is controlled using the FD map 16FD at the maximum valve lift position.
[0074]
As described above, in this embodiment, the valve lift amount can be set at three positions. Therefore, it is possible to increase the setting range of the valve lift profile while suppressing a sudden change in the control system due to the change in the setting of the valve lift amount. Can be. As a result, it is possible to further suppress deterioration of the control performance of the internal combustion engine when an abnormality occurs in the measurement system of the variable valve mechanism 200.
[0075]
E. FIG. Modification:
The present invention is not limited to the above-described examples and embodiments, but can be implemented in various modes without departing from the gist of the invention, and for example, the following modifications are possible.
[0076]
E-1. In each of the above embodiments, the number of positions where the valve lift can be set is two or three, but may be four or more, for example. In general, the change in the control method performed in response to the detection of an abnormality in the present invention may be any as long as it can be switched to a control mode in which the operating angle is set to any one of a plurality of predetermined angles.
[0077]
E-2. In each of the above embodiments, an abnormality is detected when a pulse is not continuously input from the rotary encoder 222 for a predetermined time. For example, the measurement system of the valve control system has a self-diagnosis function. The abnormality may be detected by notifying the ECU 10 of the occurrence of the abnormality detected by the function.
[0078]
Generally, the valve measurement system abnormality detection unit used in the present invention may be any unit that can detect abnormality of the measurement system of the valve control system. In the former case, the ECU 10 functions as a valve measurement system abnormality detection unit, and in the latter case, the ECU 10 and the measurement system of the valve control system function as a valve measurement system abnormality detection unit.
[0079]
Further, in each of the above embodiments, the rotary encoder is used for the measurement system. However, the position of the camshaft may be measured using, for example, a linear encoder.
[0080]
E-3. In each of the above embodiments, the bypass pipe 130 serves as a flow path for the air-fuel mixture during idling. However, the bypass pipe 130 may not be used. In this case, the flow rate of the air-fuel mixture is controlled using the throttle valve 111 even during idling.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a configuration of a control device as an embodiment.
FIG. 2 is an explanatory view showing the structure of a variable valve mechanism 200.
FIG. 3 is a perspective view of a cam 211 of the cam shaft 210 as viewed from an intake valve 153 side.
FIG. 4 is an explanatory diagram showing a relationship between a crank angle and a valve lift amount.
FIG. 5 is a flowchart showing the flow of a fail-safe process in the first embodiment.
FIG. 6 is a flowchart showing a flow of a minimum lift process performed in the fail-safe process.
FIG. 7 is a flowchart illustrating a flow of a maximum lift process performed in the fail-safe process.
FIG. 8 is a flowchart showing a flow of an intake flow rate control process in the first embodiment.
FIG. 9 is an explanatory diagram showing the contents of an intake flow rate map 16 used in the first embodiment.
FIG. 10 is a map showing a relationship between an accelerator opening and a non-linear throttle opening.
FIG. 11 is a flowchart illustrating a flow of a throttle opening calculation process in the first embodiment.
FIG. 12 is a flowchart illustrating the flow of a fail-safe process according to the second embodiment.
FIG. 13 is a flowchart illustrating a flow of an intermediate lift process performed in the fail-safe process.
FIG. 14 is an explanatory diagram showing the contents of an intake air flow map 16a used in the second embodiment.
FIG. 15 is a flowchart illustrating the flow of a fail-safe process according to the third embodiment.
FIG. 16 is an explanatory diagram showing the contents of an intake air flow map 16b used in the third embodiment.
[Explanation of symbols]
10. Electronic control unit
12: Valve lift map
16, 16a, 16b ... intake flow map
225 ... Bearing
100 ... gasoline engine
102: Spark plug
104… knock sensor
106 ... Water temperature sensor
108 ... rotation speed sensor
109 ... Accelerator sensor
110 ... intake pipe
111 ... Throttle valve
120 ... exhaust pipe
122 ... Exhaust valve
124 ... catalyst
130 ... bypass pipe
151: Valve spring
152: Valve lifter
153 ... intake valve
156 ... Cam follower
200 ... Variable valve mechanism
210 ... Cam shaft
211 ... Cam
215… Attachment
220 ... actuator
221 ... Electric motor
222 ... Rotary encoder
223 ... Slide member
224 ... Steel ball
226 ... Output shaft
227 ... motor drive unit

Claims (6)

A control device for controlling an internal combustion engine,
A valve control system for controlling a valve adjustment mechanism capable of arbitrarily adjusting a working angle, which is at least a valve opening period of a valve of the internal combustion engine, with a predetermined width;
A valve measurement system abnormality detection unit that detects an abnormality of the measurement system that the valve control system has,
With
The control device for an internal combustion engine, wherein the valve control system is capable of switching to a control mode in which the operating angle is set to one of a plurality of predetermined angles in response to the detection of the abnormality. The control device for an internal combustion engine according to claim 1,
The control device has an idling mode that is a control mode for idling, and a traveling mode that is a control mode for traveling,
The valve control system, when the abnormality is detected, according to the switching of the control mode, any one of a plurality of angles including the working angle for the idling mode and the working angle for the traveling mode Crab control to set the working angle,
The control device for an internal combustion engine, wherein the operating angle for the traveling mode is a maximum value of the predetermined width. The control device for an internal combustion engine according to claim 2, further comprising:
A throttle valve control system for controlling a throttle valve that adjusts an intake flow rate flowing into a combustion chamber of the internal combustion engine,
The valve control system, when the abnormality is detected, according to the switching of the control mode, when the control device is performing the control in the traveling mode, the valve operating angle is set to the maximum value, the When the control device is performing control in the idling mode, the working angle is set to an intermediate value smaller by a predetermined value than the maximum value,
The throttle valve control system, when the abnormality is detected, when the control device is performing control in the traveling mode, the intake air for traveling on the assumption that the operating angle is set to the maximum value. A control device for an internal combustion engine that controls a flow rate and controls an intake flow rate for idling on the assumption that the operating angle is set to the intermediate value when the control device is performing control in the idling mode. The control device for an internal combustion engine according to claim 3, wherein
The valve control system can set the operating angle to the maximum value by outputting a control output for increasing the operating angle to the valve adjusting mechanism for a first time that is predetermined. On the other hand, it is possible to set the operating angle to the intermediate value by outputting a control output for reducing the operating angle to the valve adjusting mechanism for a second time that is predetermined.
The first time is a time longer than the time during which the operating angle can be changed from the minimum state to the maximum state by a certain amount,
The control device for an internal combustion engine, wherein the second time is a time shorter than the time during which the operating angle can be changed from the maximum state to the minimum state by a fixed amount. The internal combustion engine control device according to claim 2,
The valve control system, when the abnormality is detected, according to the switching of the control mode, when the control device is performing the control in the traveling mode, the valve operating angle is set to the maximum value, the When the control device is performing control in the idling mode, the working angle is set to a minimum value obtained by the valve adjustment mechanism,
The throttle valve control system, when the abnormality is detected, when the control device is performing control in the traveling mode, the intake air for traveling on the assumption that the operating angle is set to the maximum value. A control device for an internal combustion engine that controls a flow rate and controls an intake flow rate for idling on the assumption that the operating angle is set to the minimum value when the control device is performing control in the idling mode. The control device for an internal combustion engine according to any one of claims 1 to 5,
The valve adjustment mechanism,
A camshaft having a three-dimensional cam whose shape is set so that the working angle can be changed according to the displacement in the axial direction,
An electric motor that displaces the camshaft in the axial direction according to a control output from the valve control system;
A valve spring for biasing the valve in the valve closing direction;
With
The control device for an internal combustion engine, wherein the camshaft is configured to open the valve against the valve spring by pressing the valve according to the rotation of the camshaft.

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