JP2009002258A - Variable valve timing control device of control of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve timing control device of an internal combustion engine capable of performing highly accurate diagnostic control in failure determining control. <P>SOLUTION: Therefor, this variable valve timing control device of the internal combustion engine has a variable valve timing mechanism for variably controlling the opening-closing timing of at least one valve of an intake valve or an exhaust valve, and has a speed reduction time fuel cut performing means for performing a fuel cut in response to a preset condition in speed reduction, and has a braking force detecting means for detecting output of a brake signal, and has a failure diagnosis determining means for determining whether or not the variable valve timing mechanism causes failure when switching a braking signal for switching the brake signal detected by the braking force detecting means to OFF from ON or to ON from OFF in a state of performing the fuel cut in the speed reduction by the speed reduction time fuel cut performing means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a variable valve timing control device for an internal combustion engine, and more particularly to a variable valve timing mechanism that controls the opening / closing timing of at least one of an intake valve and an exhaust valve to be variable. The present invention relates to a variable valve timing control device for an internal combustion engine that performs determination control.

  Some internal combustion engines include a variable valve timing mechanism that controls the opening / closing timing of at least one of the intake valve and the exhaust valve by changing the rotational phase of the camshaft.

JP 2004-293520 A Japanese Patent Application Laid-Open No. 2005-299677

  By the way, in a conventional variable valve timing control device for an internal combustion engine, there is a device for diagnosing a fault related to the responsiveness of a variable valve timing mechanism that controls the opening / closing timing of at least one of an intake valve and an exhaust valve to be variable. (See Patent Documents 1 and 2 above).

And what is disclosed by patent document 1 calculates the diagnostic value based on the change of an engine speed, compares this diagnostic value with the preset determination threshold value, and abnormality occurs when the diagnostic value exceeds the determination threshold value. Judging.
At this time, the change in the engine speed is a parameter used for misfire detection, and there is an inconvenience that it is difficult to determine the failure of the variable valve timing mechanism during misfire occurrence.

In addition, what is disclosed in Patent Document 2 is a variable valve that determines that a response is abnormal when a deviation between a rotation phase and a target value after a predetermined time elapses after a step change in the target value of the valve timing exceeds a predetermined value. It is a self-diagnosis device for a timing mechanism.
However, in this variable valve timing mechanism self-diagnosis device, when determining a response abnormality, a certain amount of step change in the target value of the valve timing is required. If the predetermined time or the predetermined value cannot be set accordingly, there is an inconvenience that high diagnostic accuracy cannot be obtained.

  An object of the present invention is to realize a variable valve timing control device for an internal combustion engine that can perform highly accurate diagnostic control in failure determination control.

  In view of this, the present invention provides a variable valve timing control apparatus for an internal combustion engine that includes a variable valve timing mechanism that variably controls the opening / closing timing of at least one of an intake valve and an exhaust valve in order to eliminate the inconvenience described above. The vehicle includes a deceleration fuel cut execution means for performing fuel cut according to a preset condition at the time of deceleration, and a braking force detection means for detecting the output of a brake signal. Whether the variable valve timing mechanism has failed when the braking signal is switched when the brake signal detected by the braking force detecting means is switched from on to off or from off to on in a state where the cut is being performed. Failure diagnosis determination means for determining whether or not is provided.

As described above in detail, according to the present invention, in the variable valve timing control device for an internal combustion engine provided with the variable valve timing mechanism that variably controls the opening / closing timing of at least one of the intake valve and the exhaust valve, the deceleration is performed. In some cases, the vehicle is provided with a deceleration fuel cut execution means for performing fuel cut according to a preset condition, and a braking force detection means for detecting the output of a brake signal. It is determined whether the variable valve timing mechanism has failed when the braking signal is switched when the brake signal detected by the braking force detection means is switched from on to off or from off to on. Fault diagnosis determination means is provided.
Therefore, since the failure determination control is performed at the time of deceleration that is a stable driving condition, highly accurate diagnostic control can be performed.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

1 to 4 show an embodiment of the present invention.
In FIG. 2, 1 is an internal combustion engine mounted on a vehicle, 2 is a piston, 3 is a connecting rod, 4 is a crankshaft, 5 is a combustion chamber, and 6 is a camshaft.
As shown in FIG. 2, the internal combustion engine 1 has an intake port 7 and an exhaust port 8 that communicate with the combustion chamber 5, is provided with an intake valve 9 that opens and closes the intake port 7, and an exhaust that opens and closes the exhaust port 8. A valve 10 is provided.
At this time, the intake valve 9 and the exhaust valve 10 are driven to open and close by the cam shaft 6.
An ignition plug 11 is attached to the internal combustion engine 1 so as to face the combustion chamber 5.
An ignition coil 12 is connected to the ignition plug 11. The internal combustion engine 1 is connected to a downstream end portion of an intake pipe 14 that forms an intake passage 13 that is an intake air passage communicating with the intake port 7.
The intake pipe 14 is connected to an air cleaner 15 at the upstream end, provided with a throttle valve 16 in the middle, facing the intake passage 13 on the internal combustion engine 1 side, and directed toward the intake valve 9 to an injector 17. Is attached.
The internal combustion engine 1 is connected to an upstream end portion of an exhaust pipe 19 in which an exhaust passage 18 communicating with the exhaust port 8 is formed.
A catalyst 20 is provided in the exhaust pipe 19 so as to face the exhaust passage 18.
The internal combustion engine 1 is provided with an air flow sensor (also referred to as “hot-wire air flow meter”) 21 for measuring the intake air amount in the intake passage 13, and an intake temperature sensor 22 for detecting the intake air temperature is provided in the intake passage 13. Provided.
Further, the internal combustion engine 1 includes a throttle opening sensor for detecting the throttle opening of the throttle valve 16, for example, provided with a throttle fully closed detection means 23 for detecting the fully closed state of the throttle valve 16. Also, an oxygen concentration sensor 24 for detecting the oxygen concentration in the exhaust gas is provided facing the upstream exhaust passage 18, and a cooling water temperature sensor 25 for detecting the cooling water temperature in the internal combustion engine 1 is provided. A knock sensor 26 for detecting knocking is provided, and includes a crank angle sensor for detecting the crank angle of the crankshaft 4. For example, an engine speed detecting means 27 for detecting the engine speed is provided, and the cam angle of the camshaft 6 is provided. For example, a rotational phase detector 28 for detecting the rotational phase is provided.
The ignition coil 12, the injector 17, the air flow sensor 21, the intake air temperature sensor 22, the throttle fully closed detection means 23, the oxygen concentration sensor 24, the coolant temperature sensor 25, the knock sensor 26, and the engine speed. The detection means 27, the rotational phase detection device 28, and the vehicle speed sensor 29 are connected to the control means 31 that constitutes the variable valve timing control device 30 of the internal combustion engine 1.

At this time, the variable valve timing control device 30 of the internal combustion engine 1, as shown in FIG. 2, variably controls the opening / closing timing of at least one of the intake valve 9 and the exhaust valve 10, for example, the intake valve 9. A timing mechanism 32 is provided.
The variable valve timing control device 30 includes a deceleration-time fuel cut execution unit 33 that performs fuel cut according to a preset condition during deceleration, and includes a braking force detection unit 34 that detects an output of a brake signal. The brake signal detected by the braking force detection means 34 is switched from on to off or from off to on by the fuel cut execution means 33 during deceleration while the fuel cut is being performed during deceleration. A failure diagnosis determination means 35 is provided for determining whether or not the variable valve timing mechanism 32 has failed when the braking signal is switched.
More specifically, as shown in FIG. 3, the control means 31 of the variable valve timing control device 30 includes the throttle fully closed detection means 23, a deceleration fuel cut execution means 33, a braking force detection means 34, and the engine speed. Target intake air (in this embodiment, “intake” but also “exhaust”) that receives an output signal from the detection means 27, valve timing calculation means 36, and output from the target intake valve timing calculation means 36 From the valve timing control means 37 for inputting the signal and the output signal from the rotational phase detection device 28, the response time calculating means 38 for inputting the output signal from the valve timing control means 37, and the response time calculating means 38 And the failure diagnosis determination means 35 for inputting the output signal.
Further, the variable valve timing control device 30 has a large valve overlap amount while the brake is off by a variable valve timing mechanism 32 that adjusts the rotational phase between the crankshaft 4 and the camshaft 6 of the internal combustion engine 1. The angle is advanced to a predetermined value and / or retarded to a predetermined value, and while the brake is on, the angle is retarded to a predetermined value and / or advanced to a predetermined value so that the valve overlap amount is reduced. .
Therefore, by increasing the valve overlap while the brake is off by the variable valve timing control device 30, the inflow of fresh air can be reduced and the exhaust system temperature can be maintained, and the intake pressure can be increased to prevent the oil from rising. And excessive engine braking can be suppressed.
In addition, the variable valve timing control device 30 reduces the valve overlap amount while the brake is on, thereby reducing the intake pressure and introducing a strong vacuum to the brake master bag, and is also high at idle after deceleration. Stability is obtained.
At this time, when control is performed so that the valve overlap amount is reduced while the brake is on, the predetermined value is corrected by the intake pressure and / or the engine speed so that the intake pressure does not decrease excessively.
This correction can prevent a low exhaust system temperature drop, oil rise, or excessive engine braking.

Further, as shown in FIG. 4, the failure diagnosis determination means 35 is a brake that is detected by the braking force detection means 34 while the fuel cut is being executed by the deceleration fuel cut execution means 33. When the signal is switched from ON to OFF or from OFF to ON, the time until the signal reaches a predetermined deviation with respect to the target advance amount is measured, and this measured time is the response of the variable valve timing mechanism 32. Time.
Accordingly, since the time required to reach the predetermined advance amount and / or the predetermined retard amount is set as the response time under a relatively stable condition of deceleration, a relatively high accuracy failure diagnosis result can be obtained. .
The failure diagnosis determination means 35 determines whether or not the variable valve timing mechanism 32 has responded as instructed within a time set from when the braking signal is switched.
In other words, the time set from when the braking signal is switched is the time when the advance amount reaches the value obtained by subtracting the set amount from the target advance amount or the value obtained by subtracting the set amount from the target retard amount when the brake signal is switched. As shown in FIG. 4, a failure determination time (also referred to as “failure determination threshold”) is added, and the set time is compared with the response time to set a response time. It is determined that the variable valve timing mechanism 32 is normal within the predetermined time, and the variable valve timing mechanism 32 is determined to be faulty when the response time exceeds a set time.

  Next, the operation will be described along the control flowchart of the variable valve timing control device 30 of the internal combustion engine 1 of FIG.

When the control program of the variable valve timing control device 30 of the internal combustion engine 1 starts (101), the process proceeds to determination (102) as to whether or not the monitor condition is satisfied.
If this determination (102) is YES, the process proceeds to a determination (103) of whether or not the throttle is fully closed. If the determination (102) is NO, the process proceeds to the return (116) of the control program described later. To do.

  Further, in the determination (103) of whether or not the throttle is fully closed based on the detection signal from the throttle fully closed detection means 23, if this determination (103) is YES, it is determined whether or not the fuel cut state is present ( 104), and when the determination (103) is NO, the control program returns (116).

  Further, in the determination (104) of whether or not the fuel cut state is described above, if the determination (104) is YES, that is, if the fuel cut state is set, the change of the braking force signal changes from on to off of the brake. When the determination (104) is NO, the process proceeds to the return (116) of the control program.

  Furthermore, in the determination (105) of whether or not the change in the braking force signal is a change from on to off of the brake, if this determination (105) is YES, the intake by the variable valve timing mechanism 32 is performed. When the process proceeds to the VVT advance control process (106) and the determination (105) is NO, the process proceeds to the intake VVT retard control process (107) by the variable valve timing mechanism 32.

Then, after the intake VVT advance angle control process (106) described above, the process proceeds to a process (108) for measuring the response time by the response time calculating means 38, and thereafter, the braking signal whose response time is the failure determination time. Whether the set time has been exceeded from the time of switching, that is,
The process proceeds to the determination of response time> failure determination time (109).
In this determination (109), if the determination (109) is YES, that is, if the response time exceeds the time set since the time of braking signal switching, which is the failure determination time, the failure diagnosis determination means 35 causes the intake air VVT. The process proceeds to the process (110) for determining that the responsiveness on the advance angle control side is broken, and the process proceeds to the return (116) of the control program.
If the determination (109) is NO, that is, if the response time does not exceed the time set since the time of braking signal switching, which is the failure determination time, the failure diagnosis determination means 35 causes the intake VVT advance control side to The process proceeds to a process (111) for determining that the responsiveness is normal, and the process proceeds to a return (116) of the control program.

After the process shifts to the intake VVT delay angle control process (107) by the variable valve timing mechanism 32 described above, the process shifts to a process (112) for measuring the response time by the response time calculation means 38, and then the response time. Whether or not exceeds the time set from the time of braking signal switching that is the failure judgment time, that is,
The process proceeds to judgment (113) of response time> failure judgment time.
In this determination (113), if the determination (113) is YES, that is, if the response time exceeds the time set from the time of braking signal switching, which is the failure determination time, the failure diagnosis determination means 35 causes the intake air VVT. The process proceeds to a process (114) for determining that the responsiveness on the retard angle control side has failed, and the process proceeds to the return (116) of the control program.
On the other hand, if the determination (113) is NO, that is, if the response time does not exceed the time set since switching of the braking signal, which is the failure determination time, the failure diagnosis determination means 35 causes the intake VVT retard control side to The process shifts to a process (115) for determining that the responsiveness is normal, and shifts to a return (116) of the control program.

Thereby, in the variable valve timing control device 30 of the internal combustion engine 1 provided with the variable valve timing mechanism 32 that variably controls the opening / closing timing of at least one of the intake valve 9 and the exhaust valve 10, it is preset at the time of deceleration. According to the conditions, the vehicle is provided with a deceleration fuel cut execution means 33 for performing fuel cut, and a braking force detection means 34 for detecting the output of a brake signal. The fuel cut execution means 33 for deceleration performs fuel cut during deceleration. Whether or not the variable valve timing mechanism 32 has failed when the braking signal is switched when the braking signal detected by the braking force detection means 34 is switched from on to off or from off to on. A failure diagnosis determination means 35 is provided.
Therefore, since the failure determination control is performed at the time of deceleration that is a stable driving condition, highly accurate diagnostic control can be performed.

Further, the failure diagnosis determination means 35 determines whether or not the variable valve timing mechanism 32 has responded as commanded within a time set from the time when the braking signal is switched.
Therefore, since the response time is measured for determination of failure diagnosis, and a method that can be determined simply by comparing the measured response time with a threshold value is used, for example, the calculation formula is complicated and the calculation time is required for the control device. This can be done without burden.

Furthermore, the set time is the time until the advance amount reaches the value obtained by subtracting the set amount from the target advance amount or the value obtained by subtracting the set amount from the target retard amount when the braking signal is switched. is there.
Therefore, since the set time for failure diagnosis is calculated using the value of the target advance angle (or target delay angle) that is originally required for the variable valve timing control, a new dedicated sensor or the like is prepared. There is no need.

3 is a flowchart for control of a variable valve timing control device for an internal combustion engine showing an embodiment of the present invention. It is a system block diagram of the variable valve timing control apparatus of an internal combustion engine. It is a block diagram of the variable valve timing control apparatus of an internal combustion engine. It is a time chart of the variable valve timing control apparatus of an internal combustion engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 6 Cam shaft 9 Intake valve 10 Exhaust valve 13 Intake passage 16 Throttle valve 17 Injector 18 Exhaust passage 20 Catalyst 21 Air flow sensor 22 Intake temperature sensor 23 Throttle fully closed detection means 24 Oxygen concentration sensor 25 Cooling water temperature sensor 26 Knock sensor 27 Engine speed detection means 28 Rotation phase detection device 29 Vehicle speed sensor 30 Variable valve timing control device 31 Control means 32 Variable valve timing mechanism 33 Fuel cut execution means during deceleration 34 Braking force detection means 35 Failure diagnosis determination means 36 Target intake valve timing Calculation means 37 Valve timing control means 38 Response time calculation means

Claims (3)

  In a variable valve timing control device for an internal combustion engine having a variable valve timing mechanism that variably controls the opening / closing timing of at least one of an intake valve and an exhaust valve, a fuel cut is performed in accordance with conditions set in advance during deceleration. A fuel cut execution means for deceleration, and a braking force detection means for detecting the output of a brake signal. The fuel cut execution means for deceleration is executed by the fuel cut execution means for deceleration, and the braking force detection is performed. A failure diagnosis determination means for determining whether or not the variable valve timing mechanism has failed at the time of a braking signal switching in which the brake signal detected by the means is switched from on to off or from off to on. An internal combustion engine variable valve timing control device.   The said failure diagnosis determination means is determining by whether the said variable valve timing mechanism responded according to instruction | command within the time set from the time of the said braking signal switching, The Claim 1 characterized by the above-mentioned. A variable valve timing control device for an internal combustion engine.   The set time is the time it takes for the advance amount to reach the value obtained by subtracting the set amount from the target advance amount or the value obtained by subtracting the set amount from the target retard amount when the braking signal is switched. The variable valve timing control device for an internal combustion engine according to claim 2, wherein:

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