JP2013147956A - Valve gear of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve gear of an engine capable of suitably advancing valve closing timing of an intake valve in a transient operation.SOLUTION: A valve gear 1 of an engine is provided with a variable valve gear mechanism 57 configured so as to have an electric cam speed variable mechanism making the valve characteristics of an intake valve 54 variable with a constant lifting amount as the variable valve gear mechanism capable of individually changing the valve opening timing and valve closing timing of the intake valve 54 provided in a combustion chamber E of the engine 50 with a super charger 30. The closing timing of the intake valve 54 is advanced at least by the cam speed variable mechanism in a transient operation of the engine 50. The variable valve gear mechanism 57 is made as a variable valve gear mechanism capable of individually changing the valve opening timing and the valve closing timing of the intake valve 54 by being configured so as to have a hydraulic phase variable mechanism capable of changing the valve timing of the intake valve 54 specifically.

Description

  The present invention relates to an engine valve operating device.

  In an engine, the valve characteristics of the intake valve may be variable. In this regard, as a technique that is considered to be related to the present invention, by rotating the control shaft interposed between the cam and the valve, the valve lift amount with respect to the rotational position of the cam is changed. A valve operating system for an internal combustion engine that changes the operating angle is disclosed. In this valve operating system, the operating angle and lift amount of the valve are reduced by rotating the control shaft in one direction with an electric motor, and the operating angle and lift amount of the valve are increased by rotating in the other direction. Can do.

  In addition, as a technique that is considered to be related to the present invention, for example, in Patent Document 2, it is possible to make the valve characteristics variable with a constant lift amount by making the drive shaft and the camshaft interlock at an unequal speed. A variable valve device and a valve lift characteristic detection device for a variable valve device of an internal combustion engine that detects a valve characteristic that the variable valve device makes variable are disclosed.

JP 2009-299655 A JP 2006-336659 A

  In an engine with a supercharger (for example, a compression self-ignition engine), a delay in supercharging occurs during transient operation, and as a result, unburned HC may increase or misfire may occur. In this regard, for example, the closing timing of the intake valve is advanced to thereby improve the actual compression ratio, thereby preventing or suppressing the increase in unburned HC and the occurrence of misfire. However, when the valve closing timing of the intake valve is advanced during transient operation, the following problems exist.

  FIG. 5 is a diagram showing an example of changing the valve characteristics performed during transient operation in an engine with a supercharger. FIG. 5A shows a modification example in which the valve closing timing of the intake valve 54 is advanced by a hydraulic phase variable mechanism that makes the valve timing of the intake valve 54 variable. FIG. 5B is a variable valve mechanism that includes the phase variable mechanism shown in FIG. 5A and an electric operating angle variable mechanism that varies the operating angle together with the lift amount. The example of a change in the case of advancing valve closing timing is shown. In FIG. 5, the lift amount change of the intake valve 54 before the advance angle is indicated by a broken line. The change in the lift amount of the exhaust valve 55 is also shown.

  As shown in FIG. 5 (a), when the valve closing timing of the intake valve 54 is advanced by a hydraulic phase variable mechanism, the responsiveness of the change operation is low. On the other hand, the improvement of the actual compression ratio is delayed. On the other hand, as shown in FIG. 5B, the valve closing timing of the intake valve 54 is advanced by a variable valve mechanism having a hydraulic phase variable mechanism and an electric operating angle variable mechanism. In the case of making the angle, the closing timing of the intake valve 54 can be advanced as follows.

  That is, in this case, the opening timing and closing timing of the intake valve 54 can be individually changed by a combination of changing operations. Therefore, in this case, while the response delay occurs in the hydraulic phase variable mechanism, the valve closing timing of the intake valve 54 is temporarily advanced by reducing the operating angle with the electric operating angle variable mechanism. Can be horned. As a result, the closing timing of the intake valve 54 can be advanced with good responsiveness to the supercharging delay.

  However, in this case, a drive motor that can be driven at a high speed is required for the working angle variable mechanism in order to quickly reduce the working angle. As a result, the cost of the variable valve mechanism may be increased.

  In view of the above problems, an object of the present invention is to provide a valve operating apparatus for an engine that can suitably advance the closing timing of an intake valve during transient operation.

  The present invention is a variable valve mechanism that can individually change the opening timing and closing timing of an intake valve provided for a combustion chamber of an engine with a supercharger, and the valve characteristic of the intake valve is a constant lift amount. An engine having a variable valve mechanism configured to have an electric cam speed variable mechanism that can be varied in accordance with the engine, and at the time of transient operation of the engine, at least the cam speed variable mechanism advances the valve closing timing of the intake valve This is a valve operating device.

  According to the present invention, the closing timing of the intake valve can be suitably advanced during transient operation.

It is a whole block diagram of an Example. It is a schematic block diagram of the engine of an Example. It is a figure which shows the control of an Example with a flowchart. It is a figure which shows the example of a change of the valve characteristic of an Example. It is a figure which shows the example of a change of a valve characteristic.

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

  FIG. 1 is an overall configuration diagram of the engine 50 and its surroundings. FIG. 2 is a schematic configuration diagram of the engine 50. Each component shown in FIG. 1 is mounted on a vehicle. As shown in FIG. 1, the intake system 10 includes an air flow meter 11, an intercooler 12, and an intake manifold 13. The air flow meter 11 measures the amount of intake air. The intercooler 12 cools the intake air. The intake manifold 13 distributes intake air to the cylinders 51a of the engine 50. The exhaust system 20 includes an exhaust manifold 21 and a catalyst 22. The exhaust manifold 21 merges exhaust from each cylinder 51a into one exhaust passage on the downstream side. The catalyst 22 purifies the exhaust. The supercharger 30 supercharges intake air to the engine 50.

  The supercharger 30 is an exhaust-driven supercharger and includes a compressor unit 31 and a turbine unit 32. The compressor unit 31 is provided in the intake system 10, and the turbine unit 32 is provided in the exhaust system 20. The exhaust gas recirculation system 40 includes an EGR pipe 41, an EGR cooler 42, and an EGR valve 43. The EGR pipe 41 communicates the intake system 10 and the exhaust system 20. Specifically, the EGR pipe 41 communicates the upstream collecting portion of the intake manifold 13 with the downstream collecting portion of the exhaust manifold 21. The EGR cooler 42 cools the recirculated exhaust gas. The EGR valve 43 adjusts the amount of exhaust gas recirculated.

  The engine 50 is a compression self-ignition engine. As shown in FIG. 2, the engine 50 includes a cylinder block 51, a cylinder head 52, a piston 53, an intake valve 54, an exhaust valve 55, a fuel injection valve 56, and a variable valve mechanism 57. A cylinder 51 a is formed in the cylinder block 51. A piston 53 is accommodated in the cylinder 51a. A cylinder head 52 is fixed to the upper surface of the cylinder block 51. The combustion chamber E is formed as a space surrounded by the cylinder block 51, the cylinder head 52 and the piston 53.

  The cylinder head 52 is formed with an intake port 52a and an exhaust port 52b. An intake valve 54 and an exhaust valve 55 are provided. The intake port 52 a guides intake air to the combustion chamber E, and the exhaust port 52 b exhausts gas from the combustion chamber E. The intake valve 54 opens and closes the intake port 52a, and the exhaust valve 55 opens and closes the exhaust port 52b. The cylinder head 52 is provided with a fuel injection valve 56 and a variable valve mechanism 57. The fuel injection valve 56 injects fuel into the combustion chamber E. The variable valve mechanism 57 makes the valve characteristics of the intake valve 54 variable.

  In this respect, the variable valve mechanism 57 has an electric cam speed variable mechanism that varies the valve characteristics of the intake valve 54 with a constant lift amount. Specifically, the cam speed variable mechanism lifts the valve characteristics of the intake valve 54 by causing the camshaft provided for the intake valve 54 and the drive shaft, which is a power input shaft, to operate at an unequal speed. It has a structure that makes the amount constant and variable. As the cam speed variable mechanism, for example, a drive mechanism using an electric drive motor instead of a rotary hydraulic actuator can be applied to the variable valve device disclosed in Patent Document 1 described above.

  The variable valve mechanism 57 further includes a hydraulic phase variable mechanism that makes the valve timing of the intake valve 54 variable. Specifically, the phase variable mechanism makes the valve timing of the intake valve 54 variable by changing the relative phase of the drive shaft with respect to the crankshaft of the engine 50 (that is, the opening and closing timing of the intake valve 54 is integrated). To make it variable). The variable valve mechanism 57 is configured to have a phase variable mechanism as well as a cam speed variable mechanism, so that the valve opening timing (hereinafter referred to as IVO) of the intake valve 54 and the valve closing timing (hereinafter referred to as IVO). , Referred to as IVC).

  Specifically, the variable valve mechanism 57 can change IVO and IVC individually as a result of a combination of changing operations. In this regard, the variable valve mechanism 57 advances or retards one of the IVO and IVC by, for example, a cam speed variable mechanism, and adjusts the other of the IVO and IVC by the phase variable mechanism so as not to be changed. IVO and IVC can be individually changed with a constant lift amount.

  An ECU 70 is provided for the engine 50. The ECU 70 is an electronic control unit, and as shown in FIGS. 1 and 2, a fuel injection valve 56 and a variable valve mechanism 57 are electrically connected to the ECU 70 as control targets. The air flow meter 11, the first phase sensor 81 that can detect the phase of the drive shaft relative to the phase of the crankshaft, the second phase sensor 82 that can detect the phase of the camshaft relative to the phase of the drive shaft, A sensor group 83 capable of detecting 50 operating states is electrically connected as sensors and switches. The sensor group 83 includes, for example, a crank angle sensor that can detect the rotational speed NE of the engine 50. The ECU 70 can detect IVO and IVC based on the outputs of the crank angle sensor and the phase sensors 81 and 82. Further, the fuel injection amount can be detected by the opening period of the fuel injection valve 56.

  In the ECU 70, various functional units are realized by executing processing while the CPU uses a temporary storage area of the RAM as required based on a program stored in the ROM. In this regard, in the ECU 70, for example, the following control unit is functionally realized.

  The controller advances the IVC by at least the cam speed variable mechanism during the transient operation of the engine 50. Specifically, the control unit advances the IVC to the target IVC, which is the target phase, by the phase variable mechanism, and advances the IVC by compensating for the response delay caused by the phase variable mechanism by the cam speed variable mechanism.

  In this way, when the IVC is advanced, the control unit more specifically advances the IVC to the target IVC by the phase variable mechanism, while the first advance amount that is the IVC advance amount by the phase variable mechanism The cam speed variable mechanism so that the sum of the IVC advance amount by the cam speed variable mechanism and the second advance amount is the correction IVC amount that is a correction amount necessary to advance IVC to the target IVC. To advance and adjust the IVC.

  In this respect, the ECU 70 further stores map data of IVC (hereinafter referred to as a reference IVC) preset according to the engine operating state (here, the rotational speed NE and the fuel injection amount) in the ROM. Further, map data of IVC correction amounts (hereinafter referred to as corrected IVC amounts) set in advance according to the engine operating state and acceleration (change rate ΔNE of the rotational speed NE here) is further stored in the ROM. . In the map data of the corrected IVC amount, the corrected IVC amount is set so as to increase as the degree of acceleration increases in the same engine operating state.

  The control unit determines the target IVC by using these map data, more specifically as follows. That is, the control unit detects the engine operating state and acceleration, and determines the reference IVC by reading the corresponding reference IVC from the map data of the reference IVC based on the detected engine operating state. Further, the corrected IVC amount is determined by reading the corresponding corrected IVC amount from the corrected IVC amount map data based on the detected engine operating state and acceleration. Then, the target IVC is determined by correcting the reference IVC with the corrected IVC amount.

  When the IVC is advanced by at least the cam speed variable mechanism during the transient operation of the engine 50, the control unit may control the IVC according to the engine operation state, for example, while controlling the IVC so as to become the target IVC. In this case, the IVC can be advanced by the cam speed variable mechanism while performing the changing operation based on the following concept.

  That is, in this case, the IVC is first advanced to the target IVC by the cam speed variable mechanism, and then the IVC is adjusted by the phase variable mechanism so that the IVC is not changed from the target IVC by the cam speed variable mechanism. Accordingly, the IVC can be advanced by the variable cam speed mechanism while performing the changing operation based on the concept of controlling the IVO accordingly. In this case, each changing operation may be performed in a superimposed manner. In this case, the cam speed variable mechanism temporarily replaces the IVC instead of the phase variable mechanism for the amount of advance angle that the phase variable mechanism will eventually advance when the phase variable mechanism advances the IVO. It can be advanced. In this embodiment, an engine valve gear (hereinafter referred to as a valve gear) 1 including an ECU 70 and a variable valve mechanism 57 is realized.

  Next, the control operation of the valve gear 1 performed by the ECU 70 will be described using the flowchart shown in FIG. In executing this flowchart, IVO and IVC are separately controlled in accordance with the engine operating state, and the detection necessary in this flowchart such as the engine operating state can be detected at this time. The ECU 70 determines whether or not the change amount ΔNE is larger than the reference value α (step S1). Thus, it is determined whether or not it is a transient operation. The change amount ΔNE can be calculated separately based on the rotational speed NE. If a negative determination is made in step S1, this flowchart is temporarily terminated.

  If an affirmative determination is made in step S1, the ECU 70 determines a corrected IVC amount (step S2) and a target IVC (step S2). Further, the first advance amount is detected (step S3), and it is determined whether or not the first advance amount and the corrected IVC amount are equal (step S4). If the determination is negative, it is determined that the IVC is not advanced to the target IVC by the phase variable mechanism as a result of the first advance amount being smaller than the corrected IVC amount. Therefore, if the determination is negative, the ECU 70 advances the IVC (step S5). At this time, the ECU 70 specifically advances the IVC by a phase variable mechanism.

  Subsequently, the ECU 70 detects the first and second advance amounts (step S6), and determines whether or not the sum of the first and second advance amounts is smaller than the corrected IVC amount (step S7). If the determination is affirmative, the IVC is advanced by the cam speed variable mechanism (step S8), and if the determination is negative, the sum of the first and second advance amounts becomes the corrected IVC amount by the cam speed variable mechanism. The IVC is adjusted to (step S9). After step S8 or step S9, the process returns to step S3. And if it is affirmation determination by step S4 after that, this flowchart will be complete | finished.

  Next, the function and effect of the valve gear 1 will be described. FIG. 4 is a diagram showing an example of changing the valve characteristics performed by the valve gear 1. FIG. 4A shows a case where the amount of advancement of IVC is the same in the case of the valve operating device 1 and the case described above with reference to FIG. FIG. 4B shows a case where the effects obtained in the case of the valve gear 1 and the case 1 are the same. In FIG. 4, the lift amount change of the intake valve 54 before advance is indicated by a broken line. The change in the lift amount of the exhaust valve 55 is also shown. The valve gear 1 advances the IVC at least by a cam speed variable mechanism during the transient operation of the engine 50. Thus, by increasing the actual compression ratio, it is possible to suppress an increase in unburned HC or misfire due to a delay in supercharging.

  In this regard, as shown in FIG. 4A, in the case of the valve operating apparatus 1, the IVC is advanced while reducing the operating angle with a constant lift amount. The valve overlap area of the exhaust valves 54 and 55 can be increased. For this reason, the valve operating apparatus 1 can advance IVC suitably at the time of transient operation at the point which can suppress the generation | occurrence | production of unburned HC and generation | occurrence | production of misfire suitably by the part which can improve the scavenging effect by this.

  As shown in FIG. 4B, when the valve operating device 1 obtains the same effect as in the case 1, the actual compression ratio can be lowered by the amount that the scavenging effect can be enhanced. For this reason, when the valve operating apparatus 1 obtains the same effect as in the case 1, the IVC correction amount can be set smaller and a drive motor driven at a lower speed can be used for the cam speed variable mechanism. And thereby, IVC can be advanced appropriately at the time of a transient operation also in the point which can suppress the cost of the variable valve mechanism 57 in obtaining the effect equivalent to the case of case 1.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

  For example, the engine is not necessarily limited to a compression self-ignition engine. In this regard, the present invention may be used in a spark ignition type engine such as a gasoline engine to suppress deterioration of fuel consumption and exhaust emission by obtaining good combustion during transient operation.

Valve train 1
Supercharger 30
Engine 50
Intake valve 54
Exhaust valve 55
Variable valve mechanism 57
ECU 70

Claims (1)

As a variable valve mechanism that can individually change the opening timing and closing timing of the intake valve provided for the combustion chamber of an engine with a supercharger, the valve characteristics of the intake valve can be varied with a constant lift amount. A variable valve mechanism configured to have an electrically operated cam speed variable mechanism,
A valve operating device for an engine that advances the closing timing of the intake valve by at least the cam speed variable mechanism during transient operation of the engine.

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