Control device for internal combustion engine

Abstract

To provide a control device for an internal combustion engine that can avoid generation of a closing failure in an exhaust valve even when a hydraulic oil for an engine that is supplied to a hydraulic lash adjuster (HLA) on an exhaust valve side has a low temperature and a high viscosity.SOLUTION: A control device for an internal combustion engine that performs catalyst warming-up by retarding ignition timing includes: a detector for detecting temperature of hydraulic oil that is supplied to an HLA on an exhaust valve side; an estimation unit for estimating viscosity of the hydraulic oil; and a restriction unit for restricting an amount of retard angle of the internal combustion engine on the basis of the temperature of hydraulic oil and the viscosity of the hydraulic oil.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control device for an internal combustion engine mounted on a vehicle. [Background technology]

[0002] Patent Document 1 discloses an engine (internal combustion engine) that includes a cylinder head equipped with a rocker arm type valve mechanism and a hydraulic lash adjuster (hereinafter referred to as "HLA") for optimizing the valve clearance of the intake valve and exhaust valve that are driven to open and close by the rocker arm.

[0003] In Patent Document 1, an exhaust gas passage that guides exhaust gas discharged from the combustion chamber is provided near the location where the HLA on the exhaust valve side is installed. The exhaust gas flowing through the exhaust gas passage promotes the temperature rise of the HLA on the exhaust valve side, enabling the HLA to follow the leak down in accordance with the thermal expansion of the exhaust valve, thereby preventing the exhaust valve from failing to close properly during engine warm-up. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-095625 Summary of the Invention [Problem to be solved by the invention]

[0005] Normally, the amount of expansion caused by thermal expansion of the exhaust valve due to the temperature of the exhaust gas is adjusted appropriately by the HLA on the exhaust valve side sinking in. However, if the temperature of the engine hydraulic oil (oil) supplied to the HLA on the exhaust valve side is low and the viscosity is high, the leak down time (LDT: the time required for the HLA to shrink by a certain amount), which is greatly affected by the viscosity of the hydraulic oil, becomes longer, and the sinking of the HLA cannot keep up, which can cause the exhaust valve to fail to close completely.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a control device for an internal combustion engine that can avoid exhaust valve failure even when the temperature and viscosity of the engine hydraulic oil supplied to the HLA on the exhaust valve side are low and high. [Means for solving the problem]

[0007] In order to solve the above problems, one aspect of the disclosed technology is a control device for an internal combustion engine that warms up a catalyst by retarding the ignition timing, and includes a detection unit that detects the temperature of hydraulic oil supplied to an HLA on the exhaust valve side, an estimation unit that estimates the viscosity of the hydraulic oil, and a restriction unit that restricts the amount of retardation of the internal combustion engine based on the temperature and viscosity of the hydraulic oil. [Effects of the Invention]

[0008] According to the control device for an internal combustion engine disclosed above, even when the temperature and viscosity of the engine hydraulic oil supplied to the HLA on the exhaust valve side are low, it is possible to avoid the occurrence of poor closing of the exhaust valve. [Brief explanation of the drawings]

[0009] [Figure 1] Functional block diagram of a control device for an internal combustion engine according to an embodiment of the present disclosure. [Figure 2] A flowchart of a retard control process executed by a control device for an internal combustion engine. [Figure 3] FIG. 10 is a diagram illustrating an example of a method for calculating an allowable delay amount. [Figure 4] A diagram illustrating the relationship between oil viscosity, exhaust valve extension, and HLA sinking amount DETAILED DESCRIPTION OF THE INVENTION

[0010] Generally, after starting the engine, as time passes while the catalyst is warmed up, the exhaust valve extends due to thermal expansion in accordance with the exhaust temperature (which essentially corresponds to the amount of retardation), as shown in Figure 4. Meanwhile, as the exhaust valve extends, the HLA sinks to adjust the amount of exhaust valve extension, but the amount by which the HLA can sink over time is determined by the viscosity of the engine's hydraulic oil, and its upper limit is determined.

[0011] If the HLA leak down time (LDT) is long or the engine oil viscosity is high, the exhaust valve will extend faster than the HLA can sink (the shaded area in Figure 4), preventing the exhaust valve from closing completely, resulting in poor combustion and preventing efficient catalyst warm-up.

[0012] The control device of this embodiment limits the amount of engine retardation based on the temperature and viscosity of the engine's hydraulic oil, and suppresses thermal expansion of the exhaust valve due to an increase in exhaust gas temperature, thereby avoiding poor exhaust valve closure. Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0013] <Embodiment> [composition] Fig. 1 is a functional block diagram showing an outline of a control device 100 for an internal combustion engine according to an embodiment of the present disclosure. The control device 100 illustrated in Fig. 1 includes a detection unit 110, an estimation unit 120, and a restriction unit 130. The control device 100 of this embodiment is mounted on a vehicle that uses an engine 200, which is an internal combustion engine, as a power source.

[0014] Engine 200 is an engine that includes a cylinder head (not shown) that is equipped with a rocker arm type valve mechanism and hydraulic lash adjusters (HLA) for optimizing the valve clearance of the intake valves and exhaust valves that are opened and closed by the rocker arms.

[0015] The engine 200 to which the control device 100 of this embodiment can be applied is equipped with at least the following functions: a control function that can rapidly warm the catalyst by increasing the exhaust temperature through weak stratified combustion and large retardation, a function that can detect the temperature (oil temperature) of the hydraulic oil supplied to the HLA on the exhaust valve side, and a function that can estimate the viscosity (oil viscosity) of the hydraulic oil.

[0016] The detection unit 110 of the control device 100 detects the oil temperature of the engine 200. As an example, the oil temperature is detected by the detection unit 110 acquiring a value measured by an oil temperature sensor (not shown) provided on an oil supply path connecting an oil pan (not shown) and the engine 200.

[0017] The estimation unit 120 of the control device 100 estimates the oil viscosity of the engine 200. As one example, the estimation unit 120 can estimate the oil viscosity using a well-known method such as learning of an electric oil pump (not shown) that pumps up hydraulic oil stored in an oil pan and supplies it to the engine 200.

[0018] The limiting unit 130 of the control device 100 performs processing to limit the catalyst warm-up retard amount in retard control that retards the ignition timing of the engine 200, based on the oil temperature detected by the detecting unit 110 and the oil viscosity estimated by the estimating unit 120. Note that well-known techniques can be used for retard control of the engine 200.

[0019] Note that part or all of the above-described control device 100 may be configured by an electronic control unit (ECU) that typically includes a processor such as a microcomputer, a memory, an input / output interface, etc. This electronic control unit can realize part or all of the functions performed by the above-described detection unit 110, estimation unit 120, and restriction unit 130 by having the processor read and execute a program stored in the memory.

[0020] [control] Next, the control performed by the control device 100 for an internal combustion engine according to an embodiment of the present disclosure will be described with further reference to Fig. 2. Fig. 2 is a flowchart illustrating the processing procedure of the retard control executed by each component of the control device 100 for an internal combustion engine.

[0021] (Step S201) The detection unit 110 detects the oil temperature of the engine 200. When the oil temperature is detected by the detection unit 110, the process proceeds to step S202.

[0022] (Step S202) Estimation unit 120 estimates the oil viscosity of engine 200. The method for estimating the oil viscosity is as described above. Once the oil viscosity has been estimated by estimation unit 120, the process proceeds to step S203.

[0023] (Step S203) The limiting unit 130 calculates an allowable delay amount (permissible delay amount) for engine 200 based on the oil temperature of engine 200 detected by the detecting unit 110 and the oil viscosity estimated by the estimating unit 120. This allowable delay amount is calculated using a correspondence map such as that shown in FIG. 3, for example, to maintain the exhaust gas temperature at an appropriate level and prevent misfires and the like. As an example, the limiting unit 130 calculates a delay amount that is reduced so that the hatched portion in FIG. 4 disappears. Once the allowable delay amount has been calculated by the limiting unit 130, the process proceeds to step S204.

[0024] (Step S204) The limiting unit 130 limits the catalyst warm-up delay amount, which is calculated according to the engine coolant temperature, based on the allowable delay amount calculated in step S203. When the limiting unit 130 limits the catalyst warm-up delay amount based on the allowable delay amount, the process proceeds to step S201.

[0025] <Actions and Effects> As described above, according to the internal combustion engine control device 100 of one embodiment of the present disclosure, the conditions under which poor closing (tightness in closing) of the exhaust valve occurs are estimated based on the oil temperature and oil viscosity of the engine 200, and the catalyst warm-up retard amount of the engine 200 is limited (reduced) based on these estimated conditions.

[0026] This control makes it possible to suppress the thermal expansion of the exhaust valve due to an increase in exhaust temperature, avoiding the occurrence of exhaust valve closing failure (stiffness in closing), and always maintaining an optimal exhaust state. [Industrial Applicability]

[0027] The control device of the present disclosure can be used in vehicles that use an internal combustion engine as a power source. [Explanation of symbols]

[0028] 100 control device 110 Detector 120 Estimation part 130 Restricted Section 200 Engine

Claims

[Claim 1] A control device for an internal combustion engine that warms up a catalyst by retarding ignition timing, a detection unit that detects the temperature of hydraulic oil supplied to the hydraulic lash adjuster on the exhaust valve side; an estimation unit that estimates the viscosity of the hydraulic oil; a limiting unit that limits a retard amount of the internal combustion engine based on a temperature and a viscosity of the hydraulic oil. Control device for internal combustion engines.

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