Engine control device, engine control method, and engine control program

Abstract

To provide an engine control device, an engine control method and an engine control program capable of preventing exhaust valve control from being prioritized over intake valve control when heating a purification catalyst mounted on a vehicle through a warming process while the vehicle is in a traveling state.SOLUTION: When heating a purification catalyst mounted on a vehicle through a warming process to heat the purification catalyst while the vehicle mounted with an engine is in a traveling state with the warming process not executed, an engine control device 1 puts control states of an intake valve and an exhaust valve into a first control state enabling opening and closing timings of both the intake valve and the exhaust valve to be controlled under a condition that hydraulic pressure of first oil used for driving the intake valve is equal to or larger than predetermined hydraulic pressure and hydraulic pressure of second oil used for driving the exhaust valve is equal to or larger than the predetermined hydraulic pressure.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an engine control device, an engine control method, and an engine control program for controlling an engine.

Background Art

[0002] Conventionally, technologies for heating a purification catalyst that purifies harmful substances such as hydrocarbons, carbon monoxide, and nitrogen oxides contained in exhaust gas discharged from an engine have been developed. In order for such a purification catalyst to exhibit its purification catalytic action, it is necessary to heat the purification catalyst to an appropriate temperature to activate it.

[0003] As an example of a technology for heating a purification catalyst, Patent Document 1 discloses a control device for an internal combustion engine that warms up a purification catalyst at the start of an engine by setting the combustion sharing ratio of an injector for in-cylinder injection to be equal to or higher than the combustion sharing ratio of an injector for intake passage injection and delaying the ignition timing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a vehicle such as a hybrid electric vehicle (HEV) or a plug-in hybrid electric vehicle (PHEV) is running, it may be necessary to perform a warm-up process on the purification catalyst to warm it up. In the warm-up process of the purification catalyst, the combustion state of the engine may be made into stratified combustion, and the valve opening timing of the exhaust valve may be advanced.

[0006] On one hand, due to a decrease in oil pressure caused by a decrease in the temperature of the oil used to drive the intake valve and the exhaust valve, the intake valve and the exhaust valve may not operate normally, and there is a possibility that the target valve control cannot be implemented. To avoid this, a technique for preferentially controlling either the intake valve or the exhaust valve has been developed.

[0007] However, when the closing timing of the intake valve is controlled to be delayed from the reference timing such as the closing timing used during vehicle idling or the timing when the piston reaches the bottom dead center during vehicle travel, when attempting to perform the warm-up process of the purification catalyst, if the opening timing of the exhaust valve is advanced by giving priority to the control of the exhaust valve over the control of the intake valve, ignition may occur in a state where the air-fuel mixture in the cylinder is not sufficiently compressed, and combustion failure may occur.

[0008] Regarding this point, the control device for an internal combustion engine disclosed in Patent Document 1 was not developed to solve the above-described problems.

[0009] The present disclosure provides an engine control device, an engine control method, and an engine control program capable of preventing the control of the exhaust valve from being prioritized over the control of the intake valve when heating a purification catalyst provided in a vehicle during vehicle travel.

Means for Solving the Problems

[0010] An engine control device for controlling an engine equipped with an intake valve and an exhaust valve according to one aspect includes a valve control unit that sets the control state of the intake valve and the exhaust valve to either a first control state in which the opening and closing timings of both the intake valve and the exhaust valve can be controlled or a second control state in which only the opening and closing timing of one of the intake valve and the exhaust valve can be controlled, when the vehicle equipped with the engine is in a state where the warm-up process for heating the purification catalyst provided in the vehicle is not being executed during vehicle travel and attempts to heat the purification catalyst by the warm-up process, When the hydraulic pressure of the first oil used to drive the intake valve and the hydraulic pressure of the second oil used to drive the exhaust valve are both equal to or higher than a predetermined hydraulic pressure, the valve control unit sets the control states of the intake valve and the exhaust valve to a first control state.

[0011] Further, the valve control unit can determine whether the hydraulic pressure of the first oil and the hydraulic pressure of the second oil are both equal to or higher than the predetermined hydraulic pressure, using a first flag indicating whether the hydraulic pressure of the first oil is equal to or higher than the predetermined hydraulic pressure and a second flag indicating whether the hydraulic pressure of the second oil is equal to or higher than the predetermined hydraulic pressure.

[0012] Furthermore, the first flag is set based on the rotation time of a first oil pump that controls the flow of the first oil and the rotation speed of the first oil pump at the rotation time. The second flag can be set based on the rotation time of a second oil pump that controls the flow of the second oil and the rotation speed of the second oil pump at the rotation time.

[0013] Furthermore, when the control states of the intake valve and the exhaust valve are in the first control state, after the engine stops during vehicle travel, when the hydraulic pressure of the first oil and the hydraulic pressure of the second oil become less than the predetermined hydraulic pressure, the valve control unit can change the control states of the intake valve and the exhaust valve from the first control state to a second control state.

[0014] Furthermore, when a predetermined time has elapsed since the engine stopped during vehicle travel, the valve control unit can change the control states of the intake valve and the exhaust valve from the first control state to a second control state.

[0015] An engine control method for controlling an engine equipped with an intake valve and an exhaust valve according to another aspect is such that when the engine control device during travel of a vehicle equipped with the engine, when a warm-up process for heating a purification catalyst provided in the vehicle is not being executed and an attempt is made to heat the purification catalyst by the warm-up process, When the hydraulic pressure of the first oil used to drive the intake valve is equal to or higher than a predetermined hydraulic pressure and the hydraulic pressure of the second oil used to drive the exhaust valve is equal to or higher than the predetermined hydraulic pressure, the control states of the intake valve and the exhaust valve are set to a first control state in which the opening and closing timings of both the intake valve and the exhaust valve can be controlled.

[0016] Also, when the control states of the intake valve and the exhaust valve are in the first control state, the engine control method is such that the engine control device after the engine stops during the running of the vehicle, when the hydraulic pressure of the first oil and the hydraulic pressure of the second oil become lower than the predetermined hydraulic pressure, the control states of the intake valve and the exhaust valve can be changed from the first control state to a second control state in which the opening and closing timing of only one of the intake valve and the exhaust valve can be controlled.

[0017] An engine control program for controlling an engine equipped with an intake valve and an exhaust valve according to another aspect is when the vehicle equipped with the engine is running and a warm-up process for heating a purification catalyst provided in the vehicle is not being executed, and when attempting to heat the purification catalyst by the warm-up process, for the engine control device, when the hydraulic pressure of the first oil used to drive the intake valve is equal to or higher than a predetermined hydraulic pressure and the hydraulic pressure of the second oil used to drive the exhaust valve is equal to or higher than the predetermined hydraulic pressure, the control states of the intake valve and the exhaust valve are set to a first control state in which the opening and closing timings of both the intake valve and the exhaust valve can be controlled.

[0018] Also, when the control states of the intake valve and the exhaust valve are in the first control state, the engine control program causes the engine control device after the engine stops during the running of the vehicle, when the hydraulic pressure of the first oil and the hydraulic pressure of the second oil become lower than the predetermined hydraulic pressure, the control states of the intake valve and the exhaust valve can be changed from the first control state to a second control state in which the opening and closing timing of only one of the intake valve and the exhaust valve can be controlled.

Advantages of the Invention

[0019] According to the present disclosure, when heating a purification catalyst provided in a vehicle during running of the vehicle by warm-up processing, an engine control device, an engine control method, and an engine control program capable of preventing the control of an exhaust valve from being prioritized over the control of an intake valve can be provided.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0021] <First Embodiment> Hereinafter, a first embodiment will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an engine control device 1 according to the first embodiment. The engine control device 1 is a device that controls an engine mounted on a vehicle. The engine includes a piston, a cylinder, an intake valve, and an exhaust valve. As a specific example of the engine control device 1, for example, an ECU (Electronic Control Unit) or the like can be mentioned. The engine control device 1 can communicate data with other in-vehicle devices via a network such as an in-vehicle LAN (Local Area Network).

[0022] The engine control device 1 includes an arithmetic device 10, a communication interface (I / F) 20, and a storage device 30. The communication I / F 20 is an interface that transmits and receives signals between the engine control device 1 and other devices mounted on the vehicle.

[0023] The storage device 30 is a storage device that stores the engine control program 11 executed by the arithmetic unit 10 and various information processed by the arithmetic unit 10, such as flags and the like.

[0024] The arithmetic unit 10 is an arithmetic unit such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The arithmetic unit 10 executes the engine control program 11 stored in the storage device 30, thereby executing the engine control method defined by the engine control program 11. The engine control program 11 includes a valve control unit 100, a first flag setting unit 101, a second flag setting unit 102, and a catalyst warm-up control unit 104. Note that an integrated circuit such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit) may execute the engine control program 11.

[0025] The valve control unit 100 is a program that controls the opening and closing timings of the intake valve and the exhaust valve. The valve control unit 100 sets the control state of the intake valve and the exhaust valve to either a first control state in which the opening and closing timings of both the intake valve and the exhaust valve can be controlled or a second control state in which only the opening and closing timing of one of the intake valve and the exhaust valve can be controlled.

[0026] In the first control state, when the valve control unit 100 receives a request to change the opening and closing timing of the intake valve and a request to change the opening and closing timing of the exhaust valve from another program, the valve control unit 100 controls the opening and closing timing of the intake valve based on the request to change the opening and closing timing of the intake valve and controls the opening and closing timing of the exhaust valve based on the request to change the opening and closing timing of the exhaust valve.

[0027] In the second control state, when the valve control unit 100 receives a request to change the opening / closing timing of the intake valve and a request to change the opening / closing timing of the exhaust valve from another program, it controls the opening / closing timing of the valve, prioritizing the request to change the opening / closing timing of either one of the valves.

[0028] When the hydraulic pressure of the first oil used to drive the intake valve is equal to or higher than a predetermined hydraulic pressure and the hydraulic pressure of the second oil used to drive the exhaust valve is equal to or higher than a predetermined hydraulic pressure, the valve control unit 100 sets the valve control state to the second control state. The predetermined hydraulic pressure can be a hydraulic pressure at which the intake valve and the exhaust valve can operate smoothly.

[0029] The valve control unit 100 can determine whether the hydraulic pressure of the first oil is equal to or higher than a predetermined hydraulic pressure and whether the hydraulic pressure of the second oil is equal to or higher than a predetermined hydraulic pressure, using the first flag and the second flag. The first flag is a flag indicating whether the hydraulic pressure of the first oil is equal to or higher than a predetermined hydraulic pressure. The second flag is a flag indicating whether the hydraulic pressure of the second oil is equal to or higher than a predetermined hydraulic pressure.

[0030] The first flag setting unit 101 is a program for setting the first flag. The first flag setting unit 101 can set the first flag based on the rotation time of the first oil pump that controls the flow of the first oil and the rotation speed of the first oil pump at the rotation time.

[0031] For example, when the rotation time of the first oil pump and the rotation speed of the first oil pump at the rotation time are equal to or higher than the rotation time and rotation speed assumed when the hydraulic pressure of the first oil is the predetermined hydraulic pressure (hereinafter referred to as "reference rotation time" and "reference rotation speed"), the first flag setting unit 101 sets the first flag to a value (ON) indicating that the hydraulic pressure of the first oil is equal to or higher than the predetermined hydraulic pressure. The reference rotation time and the reference rotation speed are determined by the desired hydraulic pressure, the length of the oil passage, and the diameter of the oil passage.

[0032] On the one hand, when the rotation time of the first oil pump and the rotation speed of the first oil pump at the rotation time are less than the reference rotation time and the reference rotation speed, the first flag setting unit 101 sets the first flag to a value (OFF) indicating that the hydraulic pressure of the first oil is less than the predetermined hydraulic pressure.

[0033] In other embodiments, the first flag setting unit 101 may set the first flag based on the output value of a pressure sensor that detects the hydraulic pressure of the first oil.

[0034] The second flag setting unit 102 is a program for setting the second flag. The second flag setting unit 102 can set the second flag based on the rotation time of the second oil pump that controls the flow of the second oil and the rotation speed of the second oil pump at the rotation time. The rotation time and the rotation speed of the oil pump are determined by the desired hydraulic pressure, the length of the oil passage, and the diameter of the oil passage.

[0035] For example, when the rotation time of the second oil pump and the rotation speed of the second oil pump at the rotation time are equal to or greater than the reference rotation time and the reference rotation speed, the second flag setting unit 102 sets the second flag to a value (ON) indicating that the hydraulic pressure of the second oil is equal to or greater than the predetermined hydraulic pressure. On the other hand, when the rotation time of the second oil pump and the rotation speed of the second oil pump at the rotation time are less than the reference rotation time and the reference rotation speed, the second flag setting unit 102 sets the second flag to a value (OFF) indicating that the hydraulic pressure of the second oil is less than the predetermined hydraulic pressure.

[0036] In other embodiments, the second flag setting unit 102 may set the second flag based on the output value of a pressure sensor that detects the hydraulic pressure of the second oil.

[0037] The catalyst warm-up control unit 104 is a program that controls the execution of a warm-up process for heating a purification catalyst provided in the vehicle. In the warm-up process of the purification catalyst, the catalyst warm-up control unit 104 changes the combustion state of the engine from homogeneous combustion to stratified combustion, and by opening the exhaust valve before the fuel in the combustion chamber is completely burned, the purification catalyst disposed in the exhaust pipe can be efficiently heated. The catalyst warm-up control unit 104 can achieve homogeneous combustion and stratified combustion by controlling the timing and number of fuel injections by the injector.

[0038] FIG. 2 is a flowchart showing an example of a process executed by the engine control device 1 according to the first embodiment. The process shown in FIG. 2 is executed when the vehicle equipped with the engine is about to heat the purification catalyst by a warm-up process in a state where the warm-up process for heating the purification catalyst provided in the vehicle is not being executed during traveling.

[0039] In step S1, the valve control unit 100 of the engine control device 1 determines whether the first flag is ON. If the first flag is ON (YES), the process branches to step S2. In step S2, the valve control unit 100 determines whether the second flag is ON. If the second flag is ON (YES), the process branches to step S3. In step S3, the valve control unit 100 sets the control state of the valve to the first control state, and the process returns to step S1.

[0040] If it is determined in step S2 that the first flag is not ON (NO), that is, when the first flag is OFF, the process branches to step S4. Also, if it is determined in step S3 that the second flag is not ON (NO), that is, when the second flag is OFF, the process branches to step S4. In step S4, the valve control unit 100 sets the control state of the valve to the second control state, and the process returns to step S1.

[0041] As described above, the engine control device 1 includes a valve control unit 100 that sets the control state of the intake valve and the exhaust valve to either a first control state in which the opening and closing timings of both the intake valve and the exhaust valve can be controlled, or a second control state in which only the opening and closing timing of one of the intake valve and the exhaust valve can be controlled. When the vehicle equipped with the engine is running and a warm-up process for heating the purification catalyst provided in the vehicle is not being executed, and when attempting to heat the purification catalyst by the warm-up process, the valve control unit 100 sets the control state of the intake valve and the exhaust valve to the first control state when the hydraulic pressure of the first oil used for driving the intake valve is equal to or higher than a predetermined hydraulic pressure and the hydraulic pressure of the second oil used for driving the exhaust valve is equal to or higher than the predetermined hydraulic pressure.

[0042] Normally, when delay control of the intake valve closing timing is being performed during vehicle running, the first oil and the second oil are heated by the combustion heat of the engine, causing the hydraulic pressure to increase. Therefore, the hydraulic pressure of the first oil can be equal to or higher than the predetermined hydraulic pressure, and the hydraulic pressure of the second oil can be equal to or higher than the predetermined hydraulic pressure.

[0043] By adopting the above configuration, the engine control device 1 can control both the intake valve and the exhaust valve when, during vehicle running, a warm-up process for heating the purification catalyst is not being executed and an attempt is made to heat the purification catalyst by the warm-up process. As a result, when heating the purification catalyst by the warm-up process during vehicle running, it is possible to prevent the control of the exhaust valve from being prioritized over the control of the intake valve. By enabling the control of the intake valve in this way, when the closing timing of the intake valve is controlled to be delayed compared to a reference timing such as the closing timing used during vehicle stop idling or the timing when the piston reaches bottom dead center, the closing timing of the intake valve can be quickly restored. As a result, it is possible to prevent insufficient compression of the air-fuel mixture in the cylinder and prevent combustion failure due to insufficient compression of the air-fuel mixture.

[0044] <Second Embodiment> FIG. 3 is a block diagram showing the configuration of the engine control device 1 according to the second embodiment. Hereinafter, the description will focus on the differences from the first embodiment. The engine control program 11 includes a valve control unit 100, a first flag setting unit 101, a second flag setting unit 102, a third flag setting unit 103, and a catalyst warm-up control unit 104.

[0045] The third flag setting unit 103 is a program for setting a third flag. The third flag is a flag indicating that the hydraulic pressure of the first oil and the hydraulic pressure of the second oil are less than a predetermined hydraulic pressure. The third flag setting unit 103 sets the third flag to a value (ON) indicating that the hydraulic pressure of the first oil and the hydraulic pressure of the second oil are less than the predetermined hydraulic pressure, for example, when a predetermined time has elapsed since the engine stopped during vehicle travel. The predetermined time is set to a time during which the hydraulic pressure of the first oil and the hydraulic pressure of the second oil can become less than the predetermined hydraulic pressure.

[0046] In other embodiments, the third flag setting unit 103 may set the third flag based on the output value of a pressure sensor that detects the hydraulic pressures of the first oil and the second oil.

[0047] FIG. 4 is a flowchart showing an example of the processing executed by the engine control device 1 according to the second embodiment. The processing shown in FIG. 4 is executed when the control state of the valve is the first control state.

[0048] In step S11, the valve control unit 100 of the engine control device 1 determines whether the first flag is ON. If the first flag is ON (YES), the process branches to step S12. On the other hand, if the first flag is OFF (NO), the process branches to step S14.

[0049] In step S12, the valve control unit 100 determines whether the second flag is ON. If the second flag is ON (YES), the process branches to step S13. On the other hand, if the second flag is OFF (NO), the process branches to step S14.

[0050] In step S13, the valve control unit 100 determines whether the third flag is ON. If the third flag is ON (YES), the process branches to step S14. In step S14, the valve control unit 100 changes the control state of the valve from the first control state to the second control state, and the process returns to step S11.

[0051] On the other hand, if it is determined in step S13 that the third flag is OFF (NO), the process returns to step S1. In this case, the control state of the valve remains unchanged in the first control state.

[0052] As described above, in the second embodiment, when the control states of the intake valve and the exhaust valve are in the first control state, after the engine stops during the running of the vehicle, when the oil pressure of the first oil and the oil pressure of the second oil become less than the predetermined oil pressure, the valve control unit 100 changes the control states of the intake valve and the exhaust valve from the first control state to the second control state.

[0053] When a vehicle such as a hybrid vehicle or a plug-in hybrid vehicle is running only on the motor, the temperatures of the first oil and the second oil decrease, and their oil pressures may become less than the predetermined oil pressure. At this time, if an attempt is made to operate both the intake valve and the exhaust valve, there is a possibility that neither the intake valve nor the exhaust valve will operate normally.

[0054] In the second embodiment, when the oil pressure of the first oil and the oil pressure of the second oil become less than the predetermined oil pressure, that is, when there is a possibility that neither the intake valve nor the exhaust valve will operate normally, the valve control unit 100 changes the control states of the intake valve and the exhaust valve from the first control state to the second control state, and gives priority to the opening / closing control of either the intake valve or the exhaust valve. As a result, malfunction of the intake valve and the exhaust valve can be avoided.

[0055] In the above example, when the program is loaded into a computer, it includes a set of instructions (or software code) for causing the computer to perform one or more functions described in the embodiments. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, the computer-readable medium or tangible storage medium includes random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD), or other memory technologies, CD-ROM, digital versatile disk (DVD), Blu-ray (registered trademark) disk, or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may also be transmitted on a transitory computer-readable medium or a communication medium. By way of example and not limitation, the transitory computer-readable medium or communication medium includes electrical, optical, acoustic, or other forms of propagated signals.

[0056] The present invention is not limited to the above-described embodiments, and can be appropriately modified without departing from the spirit of the present invention.

Explanation of Reference Numerals

[0057] 1 Engine control device 10 Arithmetic unit 20 Communication interface 30 Storage device 11 Engine control program 100 Valve control unit 101 First flag setting unit 102 Second flag setting unit 103 Third flag setting unit 104 Catalyst warm-up control unit

Claims

1. An engine control device for controlling an engine equipped with an intake valve and an exhaust valve, comprising a valve control unit that sets the control state of the intake valve and the exhaust valve to either a first control state in which the opening and closing timings of both the intake valve and the exhaust valve can be controlled or a second control state in which only the opening and closing timing of one of the intake valve and the exhaust valve can be controlled, when attempting to heat the purification catalyst by the warm-up process in a state where the warm-up process of heating the purification catalyst provided in the vehicle on which the engine is mounted is not being executed during the running of the vehicle, the valve control unit sets the control state of the intake valve and the exhaust valve to the first control state when the hydraulic pressure of the first oil used for driving the intake valve is equal to or higher than a predetermined hydraulic pressure and the hydraulic pressure of the second oil used for driving the exhaust valve is equal to or higher than a predetermined hydraulic pressure, in the first control state, when the valve control unit receives a request to change the opening and closing timing of the intake valve and a request to change the opening and closing timing of the exhaust valve, the valve control unit controls the opening and closing timing of the intake valve based on the request to change the opening and closing timing of the intake valve and controls the opening and closing timing of the exhaust valve based on the request to change the opening and closing timing of the exhaust valve, the valve control unit uses a first flag indicating whether the hydraulic pressure of the first oil is equal to or higher than a predetermined hydraulic pressure and a second flag indicating whether the hydraulic pressure of the second oil is equal to or higher than a predetermined hydraulic pressure to determine whether the hydraulic pressure of the first oil is equal to or higher than a predetermined hydraulic pressure and the hydraulic pressure of the second oil is equal to or higher than a predetermined hydraulic pressure, Engine control device.

2. A first flag setting unit that sets the first flag, and a second flag setting unit that sets the second flag, the first flag setting unit turns on the first flag when a first rotation time indicating a period during which a first oil pump that controls the flow of the first oil rotates and the rotation speed of the first oil pump at the first rotation time are each equal to or higher than a reference rotation time and a reference rotation speed of the first oil pump assumed when the hydraulic pressure of the first oil reaches the predetermined hydraulic pressure, The second flag setting unit turns on the second flag when a second rotation time indicating a period during which a second oil pump that controls the flow of the second oil rotates and the rotation speed of the second oil pump at the second rotation time are each equal to or greater than a reference rotation time and a reference rotation speed of the second oil pump assumed when the oil pressure of the second oil reaches the predetermined oil pressure. The valve control unit determines that the oil pressure of the first oil is equal to or higher than a predetermined oil pressure when the first flag is on, and determines that the oil pressure of the second oil is equal to or higher than a predetermined oil pressure when the second flag is on. The engine control device according to claim 1.

3. An engine control method for controlling an engine including an intake valve and an exhaust valve, the engine control device being When the vehicle equipped with the engine is running and a warm-up process for heating a purification catalyst provided in the vehicle is not being executed, if an attempt is made to heat the purification catalyst by the warm-up process, when the oil pressure of a first oil used to drive the intake valve is equal to or higher than a predetermined oil pressure and the oil pressure of a second oil used to drive the exhaust valve is equal to or higher than a predetermined oil pressure, the control state of the intake valve and the exhaust valve is set to a first control state capable of controlling the opening and closing timings of both the intake valve and the exhaust valve. In the first control state, when a change request for the opening and closing timing of the intake valve and a change request for the opening and closing timing of the exhaust valve are received, the opening and closing timing of the intake valve is controlled based on the change request for the opening and closing timing of the intake valve, and the opening and closing timing of the exhaust valve is controlled based on the change request for the opening and closing timing of the exhaust valve. Using a first flag indicating whether or not the oil pressure of the first oil is equal to or higher than a predetermined oil pressure and a second flag indicating whether or not the oil pressure of the second oil is equal to or higher than a predetermined oil pressure, it is determined whether or not the oil pressure of the first oil is equal to or higher than a predetermined oil pressure and the oil pressure of the second oil is equal to or higher than a predetermined oil pressure. Engine control method.

4. An engine control program for controlling an engine including an intake valve and an exhaust valve, for an engine control device When the vehicle equipped with the engine is running and the warm-up process for heating the purification catalyst provided in the vehicle is not being executed, if an attempt is made to heat the purification catalyst by the warm-up process, when the hydraulic pressure of the first oil used for driving the intake valve is equal to or higher than a predetermined hydraulic pressure and the hydraulic pressure of the second oil used for driving the exhaust valve is equal to or higher than a predetermined hydraulic pressure, the control states of the intake valve and the exhaust valve are set to a first control state capable of controlling the opening and closing timings of both the intake valve and the exhaust valve. In the first control state, when the engine control device receives a request to change the opening and closing timing of the intake valve and a request to change the opening and closing timing of the exhaust valve, the opening and closing timing of the intake valve is controlled based on the request to change the opening and closing timing of the intake valve, and the opening and closing timing of the exhaust valve is controlled based on the request to change the opening and closing timing of the exhaust valve. Using a first flag indicating whether the hydraulic pressure of the first oil is equal to or higher than a predetermined hydraulic pressure and a second flag indicating whether the hydraulic pressure of the second oil is equal to or higher than a predetermined hydraulic pressure, it is determined whether the hydraulic pressure of the first oil is equal to or higher than a predetermined hydraulic pressure and the hydraulic pressure of the second oil is equal to or higher than a predetermined hydraulic pressure. Engine control program.

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