JP2011185248A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a failure diagnosis device of a valve stopping mechanism that can determine a failure of the valve stopping mechanism with good accuracy and small load to a calculator. <P>SOLUTION: Based on a stopping request, the failure diagnosis device of an internal combustion engine can stop an actuation of intake and exhaust valves of an unprescribed cylinder by using solenoids 41 and 42 of the intake and exhaust valves, respectively. The failure diagnosis device assesses a pumping loss state of the cylinder based on a vehicle deceleration assessed by an output of, for example, a vehicle speed sensor 35, and an amount of regenerated power of an MG (motor generator) 21 received from an MG control ECU 2. By comparing the assessed pumping loss state to a pumping loss state when a valve stop is performing normally, the failure diagnosis of the valve stopping mechanism is conducted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an internal combustion engine including a valve stop mechanism that can stop an intake valve or an exhaust valve of an arbitrary cylinder in response to a stop request in a multi-cylinder internal combustion engine, and in particular, a failure that performs failure diagnosis of the valve stop mechanism. The present invention relates to an internal combustion engine having a diagnostic device.

  In a multi-cylinder internal combustion engine, an internal combustion engine having a cylinder resting operation mode in which the operation of some of the cylinders is stopped by stopping the operation of the intake and exhaust valves is known. A technique disclosed in Patent Document 1 is known as an operation state determination device for determining the operation state of an intake / exhaust valve in such an internal combustion engine. This device detects the operating state of each cylinder and the operating state of the intake / exhaust valve based on the change in the cylinder pressure with respect to the combustion chamber volume of each cylinder.

JP 2002-256950 A

  However, in the above determination method, it is necessary to accurately grasp the temporal change in the in-cylinder pressure, so the accuracy of the pressure sensor is required, and the actual determination is performed after conversion to a polytropic index. Further, the computer load of the determination unit that performs the determination increases. Furthermore, when the pressure sensor is defective, there is a problem that it is difficult to determine this as a failure of the intake / exhaust valve.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an internal combustion engine having a failure diagnosis device for a valve stop mechanism that has a small computer load and can accurately determine a failure of the valve stop mechanism.

  In order to solve the above-described problem, an internal combustion engine according to the present invention includes a valve stop mechanism that holds an intake valve or an exhaust valve of a specific cylinder in response to a valve stop request, and pumps the specific cylinder. The apparatus further comprises a pumping loss detecting means for detecting a loss state and a failure diagnosis device for determining a failure of the valve stop mechanism based on the pumping loss state detected at the time of the valve stop request.

  When detecting the pumping loss, it is preferable to further include deceleration detecting means for detecting the deceleration of the vehicle, and to determine the pumping loss state based on the detected deceleration. Further, in the case of a vehicle including a generator that performs regenerative power generation using the kinetic energy of the vehicle, the vehicle further includes a regenerative power generation amount detecting unit that detects the power generation amount of the generator, and based on the detected regenerative power generation amount. It is good to determine the pumping loss state.

  When the in-cylinder pressure sensor for detecting the in-cylinder pressure of the specific cylinder is further provided, the failure diagnosis device further detects an abnormality in the in-cylinder pressure sensor based on the pumping loss state and the in-cylinder pressure at the time of the detected valve stop request. It is good to detect. In this case, the failure diagnosis device may perform failure diagnosis of the valve stop mechanism in consideration of the detected in-cylinder pressure.

  If the valve is stopped normally when the cylinder is closed, the pumping loss of intake and exhaust is reduced compared to when the valve is not stopped normally. The failure determination of the valve stop mechanism can be performed by comparison. Thereby, the failure of the valve stop mechanism can be accurately determined by a simple method.

  When the pumping loss is reduced, if the other conditions are the same, the engine braking force is reduced, so that the deceleration of the vehicle is reduced. Therefore, the pumping loss can be determined by comparing the deceleration of the vehicle. Similarly, in the case of a vehicle equipped with a regenerative generator, when the pumping loss is reduced, the regenerative power increases, so that the pumping loss can be determined based on the regenerative power.

It is a block diagram of a failure diagnosis device for a valve stop mechanism according to the present invention. 2 is a flowchart illustrating a first embodiment of a failure diagnosis process in the apparatus of FIG. 1. It is a flowchart which shows 2nd Embodiment of the failure diagnosis process in the apparatus of FIG. It is a graph which compares and shows the case where the valve stop mechanism is functioning normally, and the cylinder pressure change of each failure state.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same reference numerals are given to the same components in the drawings as much as possible, and duplicate descriptions are omitted.

  FIG. 1 shows a block diagram of a failure diagnosis device for a valve stop mechanism according to the present invention. The failure diagnosis apparatus in this embodiment is provided by software as part of an engine control ECU (Electronic Control Unit) 1 that controls the engine. The engine control ECU 1 includes an ADC (Analog Digital Converter) 10 that converts an input analog signal into a digital signal, a CPU (Central Processing Unit) 11 that performs calculation processing, a RAM (Randam Access Memory) 12 that is a storage device, a ROM ( Read only memory) 13. When all of the input signals are digital signals, the ADC 10 is unnecessary, and an AD converter may be provided outside for analog signal conversion, and the digital output signal may be input to the ECU. Further, the failure diagnosis device may be provided independently of the engine control ECU 1 and can be integrated with other ECUs.

  The engine control ECU 1 includes an accelerator opening sensor 31 that detects an operation amount of an accelerator pedal, a shift sensor 32 that detects a shift state of the transmission, an in-cylinder pressure sensor 33 that detects an in-cylinder pressure of each cylinder, Outputs of a crank angle sensor 34 that detects the crank angle and a vehicle speed sensor 35 that detects the vehicle speed are input.

  On the other hand, the engine control ECU 1 controls the operation of the intake valve solenoid 41 and the exhaust valve solenoid 42 for stopping the operation of the intake valve and the exhaust valve of each cylinder in response to a stop request, and the operation of the injector 43 for supplying fuel. Control signal for output.

  The engine control ECU 1 also has a function of communicating with an MG control ECU 2 that controls an MG (Motor Generator) 21 that is an electric motor that also functions as a regenerative generator.

  Next, failure diagnosis processing according to the present embodiment will be described. FIG. 2 is a flowchart showing the processing flow of the first embodiment. The processing shown in FIG. 2 is repeatedly executed by the engine control ECU 1 at a predetermined timing while the engine is operating.

  First, it is determined whether or not a valve stop request is being made (step S1). If the valve stop request is not being issued, failure diagnosis processing by the method described later cannot be performed, and the subsequent processing is skipped and the processing ends. This valve stop request is executed under conditions such as “fuel cut operation” in which fuel injection is stopped for a specific cylinder, such as during deceleration. When the valve stop request is being made, the process proceeds to step S4, where the vehicle deceleration a is calculated based on the output of the vehicle speed sensor 35, and the regenerative power generation amount g of the MG 21 is received from the MG control ECU 2.

  In step S5, the calculated vehicle deceleration a and the regenerative power generation amount g are compared with the vehicle deceleration a1 and the regenerative power generation amount g1 that are stored in the ROM 13 during normal idle cylinder operation. For a1 and g1, numerical values corresponding to the accelerator opening obtained by the accelerator opening sensor 31, the shift state obtained by the shift sensor 32, and the crank angle obtained by the crank angle sensor 34 are stored in the ROM 13, respectively. It is desirable to be able to calculate by correcting the influence.

  If a is larger than a1 by a certain threshold value β or g is larger than g1 by a certain threshold value γ, the process proceeds to step S6, where it is determined that the valve stop mechanism has failed. . On the other hand, in step S5, when a is a1 + β or less and g is within g1 + γ, it is determined that the valve stop mechanism is operating normally, and the process ends. Here, no special processing is performed at the normal time, but a flag value indicating a normal value may be set, for example.

  Here, when one or both of the valve stop mechanisms of the intake valve / exhaust valve fails, a valve opening operation is performed on the valve side where the valve stop mechanism is not operating normally with the operation of the engine. Therefore, air is sucked into and discharged from the cylinder through this. As a result, the pumping loss increases as compared with the case where the valve is stopped normally. As a result, the power used to idle the cylinder increases. That is, the deceleration at the time of fuel cut increases and the amount of regenerative power generation becomes smaller than when the cylinder resting operation is normally performed. In the present invention, the failure of the valve stop mechanism can be accurately determined by determining the pumping loss state using the vehicle deceleration and the regenerative power generation amount. Furthermore, the number of failed valves can be detected based on the magnitude of the difference between the vehicle deceleration and the normal amount of regenerative power generation.

  Next, a second embodiment of the determination process will be described with reference to the process flow of FIG. Similar to the first embodiment, this process is also repeatedly executed by the engine control ECU 1 at a predetermined timing while the engine is operating.

  First, as in the first embodiment, it is determined whether or not a valve stop request is being made (step S1). If the valve stop request is not being issued, failure diagnosis processing by the method described later cannot be performed, and the subsequent processing is skipped and the processing ends.

  When the valve stop request is being made, the process proceeds to step S2 where the in-cylinder pressure value acquired from the in-cylinder pressure sensor 33 is sampled by the ADC 10 and the constant angular period is determined based on the crank angle acquired from the crank angle sensor 34. AD conversion with. In the subsequent step S3, the sampled in-cylinder pressure value P is compared with the in-cylinder pressure value P1 stored in the ROM 13 during normal cylinder resting operation. The in-cylinder pressure value P1 is stored in the ROM 13 corresponding to the crank angle acquired from the crank angle sensor 34. When the difference (absolute value) between the two is within a certain threshold value α, it is determined that the state is normal, and the subsequent processing is skipped by returning to step S1. On the other hand, if the difference (absolute value) between the two exceeds the threshold value α, the process proceeds to step S4, and the vehicle deceleration is based on the output of the vehicle speed sensor 35, as in the first embodiment. While calculating a, the regenerative electric power generation amount g of MG21 is received from MG control ECU2.

  The processes in steps S5 and S6 are the same as in the first embodiment. Thereby, it is possible to accurately determine the failure of the valve stop mechanism in consideration of both the in-cylinder pressure and the pumping loss state. On the other hand, in step S5, when a is a1 + β or less and g is within g1 + γ, the process proceeds to step S7, and it is determined that the in-cylinder pressure sensor 33 is out of order.

  The above processing flow is an example. For example, the pumping loss state may be determined first to determine the in-cylinder pressure, or both may be determined simultaneously.

  Here, when the operations of both the intake valve and the exhaust valve are normally stopped based on the valve stop request, a pressure-volume change as shown in FIG. When both valve stop mechanisms are open and a sticking failure has occurred (in this case, the intake and exhaust valves are opened and closed based on the normal intake and exhaust timing), as shown in FIG. Pressure-volume change is shown. In addition, when the intake valve has stopped operating normally, but the exhaust valve is open and a sticking failure has occurred, a change in pressure-volume as shown in FIG. 4C is shown. According to the present invention, it is possible to perform the determination with higher accuracy than when performing the failure determination using only the in-cylinder pressure sensor, and it is also possible to perform the failure determination of the sensor at the same time.

  Here, an example in which the pumping loss state is determined using both the vehicle deceleration and the regenerative power generation amount has been described, but it is also possible to determine using only one of them. The present invention can be suitably applied to a vehicle that does not include a regenerative generator by making a determination using vehicle deceleration. In addition, the pumping loss state can be determined based on fluctuations in engine speed. In the above description, the example in which the vehicle deceleration is determined from the vehicle speed has been described. However, the vehicle deceleration may be directly measured using an acceleration sensor.

  DESCRIPTION OF SYMBOLS 1 ... Engine control ECU, 2 ... MG control ECU, 10 ... ADC, 11 ... CPU, 12 ... RAM, 13 ... ROM, 21 ... MG, 31 ... Accelerator opening sensor, 32 ... Shift sensor, 33 ... In-cylinder pressure sensor, 34 ... Crank angle sensor, 35 ... Vehicle speed sensor, 41 ... Intake valve solenoid, 42 ... Exhaust valve solenoid, 43 ... Injector.

Claims (5)

In an internal combustion engine comprising a valve stop mechanism that holds an intake valve or an exhaust valve of a specific cylinder closed in response to a valve stop request,
A pumping loss detecting means for detecting a pumping loss state of the specific cylinder;
An internal combustion engine further comprising a failure diagnosis device that performs failure determination of the valve stop mechanism based on a pumping loss state detected at the time of a valve stop request. The vehicle further comprises deceleration detection means for detecting the deceleration of the vehicle,
The internal combustion engine according to claim 1, wherein the pumping loss detecting means determines a pumping loss state based on the detected deceleration. A generator for generating regenerative power using the kinetic energy of the vehicle;
It further comprises regenerative power generation amount detection means for detecting the power generation amount of the generator,
The internal combustion engine according to claim 1, wherein the pumping loss detection means determines a pumping loss state based on the detected amount of regenerative power generation. The in-cylinder pressure sensor for detecting the in-cylinder pressure of the specific cylinder is further provided, and the failure diagnosis device further detects an abnormality in the in-cylinder pressure sensor based on the detected pumping loss state and the in-cylinder pressure when the valve stop request is detected. The internal combustion engine according to claim 1 to be detected. The internal combustion engine according to claim 4, wherein the failure diagnosis device performs failure diagnosis of the valve stop mechanism in consideration of the detected in-cylinder pressure.

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