Method for confirming a valve phase during the starting of an internal combustion engine and vehicle operation control

Abstract

Method for confirming a valve phase during the starting of an internal combustion engine, wherein the method confirms a valve phase during the starting of an internal combustion engine having a variable valve timing system configured to adjust the valve phase of the internal combustion engine, wherein the method includes: Shifting the valve phase to a most delayed position by the variable valve timing system when starting the internal combustion engine; successively determining whether a valve phase deviation, i.e. a difference between output values ​​of a cam angle sensor at a consecutive time, is below a specified reference deviation; Confirming the valve phase, that the valve phase has reached the most delayed position, in the case where the valve phase deviation is below the reference deviation; Using the valve phase for starting control of the internal combustion engine; wherein the system is configured with variable valve timing to allow adjustment of the valve phase by electrical actuation, and is used to adjust an inlet valve phase; further showing the procedure: Terminating a series of processing to confirm the valve phase in the case where the valve phase is not confirmed at a time when a cylinder determination is completed during the processing for cylinder determination, which is performed separately.

Description

Technical field

[0001] The present invention relates to a method for confirming a valve phase during the starting of an internal combustion engine and to a vehicle operation control system, and in particular to an improvement of the starting characteristics of the internal combustion engine and the like. Background of the invention

[0002] It is generally known that a variable valve timing system (hereinafter referred to as "VVT") is used in motor vehicles to improve the fuel consumption of an internal combustion engine, driving performance, and the like. The VVT ​​system can adjust a valve phase, that is, a valve position, when the valve opens / closes.

[0003] Two types of such VVT systems are available: a hydraulically actuated VVT system configured to adjust the valve phase by hydraulic pressure, and an electrically actuated VVT system configured to adjust the valve phase using an electric motor.

[0004] In comparison to the VVT ​​system with hydraulic drive, the VVT ​​system with electric drive has the advantage that a limitation range under an environmental condition, such as temperature, is limited and the VVT ​​system with electric drive can therefore be used in a wide range.

[0005] In the case of the hydraulically actuated VVT system, the valve phase returns to its initial position after the engine is switched off, due to its design. By adding a locking mechanism, the initial position can therefore be maintained until the next engine restart, allowing the engine to be restarted without any problems.

[0006] The structure of an electrically actuated VVT system differs from that of the hydraulically actuated VVT system described above. The electrically actuated VVT system is not designed to allow the valve to return to its initial position after the engine is switched off. Due to its design, it is difficult to incorporate a locking mechanism into the electrically actuated VVT system. Consequently, it is standard practice for electrically actuated VVT systems to be designed without such a locking mechanism.

[0007] For this reason, after the vehicle is switched off (ignition off) and an external force is applied to the vehicle, the valve phase may change from the valve phase at the time the system was at a standstill.

[0008] If an ignition switch is turned on after the system has been shut down, the valve phase may differ from the valve phase at the time of the last system shutdown, and phase shift detection is required. Otherwise, misfires or abnormal combustion may occur.

[0009] Therefore, for a vehicle using an electric drive with a VVT system, it is absolutely essential to detect the valve phase when starting an engine.

[0010] When starting an engine, it is generally necessary to know the cylinder position and the valve position at startup. Methods for determining the engine cylinder and calculating the valve phase using a crankshaft angle detected by a crankshaft angle sensor and a camshaft angle detected by a camshaft angle sensor, and the like, are therefore conventionally known (see, for example, Japanese patent disclosure JP 2003-56381A). However, such methods exhibit the following problems.

[0011] In the method for determining the engine's cylinder using the crankshaft angle, detected by the crankshaft angle sensor, and the camshaft angle, detected by the camshaft angle sensor, the rate of cylinder determination depends on the starter motor's rotational frequency. For example, the starter motor's rotational frequency decreases in a low-temperature environment due to a reduction in battery voltage. Consequently, the time required to determine the cylinder becomes longer than normal, and the engine's starting time is also longer than at temperatures near normal.

[0012] Furthermore, this method does not preserve the valve timing until the cylinder determination is complete. Consequently, the valve timing cannot be changed while the cylinder is being determined. For this reason, it is also difficult to shorten the engine starting time.

[0013] The JP 2005 - 264 764 A refers to a valve control device for an internal combustion engine with a locking mechanism.

[0014] The present invention was made in view of the above circumstances and therefore provides a method for confirming a valve phase when starting an internal combustion engine and a vehicle operating control system capable of immediately confirming the valve phase when starting the internal combustion engine. Disclosure of the invention

[0015] To achieve the above purpose of the present invention, a method for confirming a valve phase during the starting of an internal combustion engine according to the present invention is required. A method for confirming a valve phase during the starting of an internal combustion engine, which confirms a valve phase during the starting of an internal combustion engine having a variable valve timing system configured to adjust the valve phase of the internal combustion engine, wherein the method comprises: Shifting the valve phase to a most delayed position by the variable valve timing system during engine start-up; successively determining whether a valve phase deviation, i.e., a difference between output values ​​of a cam angle sensor at a consecutive time, is below a specified reference deviation; confirming that the valve phase has reached the most delayed position if the valve phase deviation is below the reference deviation; and using the valve phase for engine start-up control; wherein the variable valve timing system is configured to adjust the valve phase by electrical actuation and is used to adjust an intake valve phase; further showing the procedure: Terminating a series of processing to confirm the valve phase in the case where the valve phase is not confirmed at a time when a cylinder determination is completed during the processing for cylinder determination, which is performed separately.

[0016] In order to achieve the aforementioned purpose of the present invention, a vehicle operation control system according to the present invention is also required. a vehicle operating control system configured to perform operating control for an internal combustion engine using an electronic control unit, and the internal combustion engine has a variable valve timing system configured to adjust the valve phase of the internal combustion engine.

[0017] The electronic control unit is configured to: shift the valve phase to a most delayed position by the variable valve timing system during engine start-up; successively determine whether a valve phase deviation, that is, a difference between output values ​​of a cam angle sensor at a consecutive time, is below a specified reference deviation; confirm that the valve phase has reached the most delayed position if the valve phase deviation is below the reference deviation; and use the valve phase for engine start-up control, wherein the variable valve timing system is configured to adjust the valve phase by electrical actuation and is used to adjust an intake valve phase.wherein the electronic control unit is configured to: be able to perform cylinder determination processing for the internal combustion engine separately; and to terminate a series of processing for confirming the valve phase in the event that the valve phase is not confirmed at a time when cylinder determination processing is completed.

[0018] According to the present invention, the valve phase is forcibly changed with the most delayed position as a target, and it is determined that the valve phase has reached the most delayed position as an endpoint when the change in the output value of the cam angle sensor becomes equal to or less than the specified value. In this way, the valve phase can be confirmed immediately during starting. Compared to the case where the valve phase is confirmed by conventional cylinder determination, the following effects can therefore be achieved: the valve phase can be confirmed immediately with a high degree of probability during starting, the starting time of the internal combustion engine can be reduced, and the starting reliability of the engine can be improved. Brief description of the drawings Fig. Figure 1 is a configuration view illustrating a configuration example of a vehicle operation control in an embodiment of the present invention. Fig. Figure 2 is a configuration view illustrating a system configuration example of an electrical system for performing a valve phase confirmation processing during the starting of an internal combustion engine by the vehicle operating control according to the embodiment of the present invention. Fig. Figure 3 is a flowchart of a subroutine to illustrate a process of processing for valve phase confirmation during the starting of the internal combustion engine, which is carried out by the vehicle operating control according to the embodiment of the present invention. Fig. Section 4 contains graphs for schematically illustrating changes in the state of main sections at the time when the processing for valve phase confirmation during the starting of the internal combustion engine is carried out according to the embodiment of the present invention, wherein Fig. 4A is a schematic graph to illustrate the presence or absence of a power supply voltage, Fig. 4B is a schematic graph illustrating changes in a target phase angle of a valve and an actual phase angle of the valve, determined by an electrically actuated VVT system. Fig. 4C is a schematic graph to illustrate a point in time at which an endpoint determination takes place, Fig. 4D is a schematic graph to illustrate a starting point for starting, Fig. 4E is a schematic graph to illustrate a change in the speed of a power engine, Fig. 4F is a schematic graph to illustrate a completion time of determining a cylinder, and Fig. 4G is a schematic graph to illustrate a starting point of ignition. Description of the specific embodiment

[0019] Below is a description of one embodiment of the present invention with regard to the Fig. 1 to 4 will take place.

[0020] Note that the elements, arrangements and the like described below do not limit the present invention and various modifications may be made to them within the scope of the present invention.

[0021] First, a description of a configuration example of a vehicle operating control system, to which a method for confirming a valve phase during the starting of an internal combustion engine according to the embodiment of the present invention is applied, is given with regard to the Fig. 1 and Fig. 2 will follow.

[0022] The vehicle operation control according to the embodiment of the present invention is particularly suitable for valve phase control by a VVT system with electric drive (a detailed description will follow later).

[0023] More precisely, the vehicle operating control system according to the embodiment of the present invention is configured to include as its main components a power engine ECU (referred to as the “E-ECU”). Fig. 1 described) 51, which uses an electronic control unit, a VVT system 1 with electric drive, a crank angle sensor 2, a cam angle sensor 3 and a rotation frequency sensor 4 of a VVT motor with electric drive.

[0024] Similar to the related technology, the engine ECU 51 is configured to perform various types of control required for vehicle driving control, and examples of such control include speed control and fuel injection control for an engine 5 such as the internal combustion engine.

[0025] Such a power machine ECU 51 is configured to include, for example, the following as its main components: a microcomputer with a known / generally known configuration as a central component; a memory element (not illustrated), such as random access memory (RAM) or read-only memory (ROM); and an input / output interface circuit (not illustrated).

[0026] This engine ECU 51 receives detection signals from the crankshaft angle sensor 2, the camshaft angle sensor 3, and the rotational speed sensor 4 of an electrically driven VVT engine, as well as various signals, such as accelerator pedal position and vehicle speed, which are detected by sensors (not illustrated) or the like and are required for vehicle operation control. In addition to engine speed control and fuel injection control, the various signals received by the engine ECU 51 are also used for processing to confirm valve phases during engine start-up according to the embodiment of the present invention, which will be described later, and the like.

[0027] The electrically actuated VVT system 1 is a system with variable valve timing. This electrically actuated VVT system 1 is specifically configured to control the valve phase via an electrically actuated VVT actuator 1a (see Fig. 2) to be able to adjust using a motor, and a basic configuration of the same is similar to the conventional VVT system with electric drive.

[0028] It is assumed that a VVT system 1 with an electric drive is provided at at least one inlet valve (not illustrated) and / or one exhaust valve (not illustrated) of the engine 5, such as the internal combustion engine. In the embodiment of the present invention, the VVT ​​system 1 with an electric drive is configured to be provided on the inlet valve side.

[0029] The engine 5 is configured so that power obtained through a crankshaft 6 is transmitted to an intake camshaft 11 and an exhaust camshaft 12 via sprockets 8, 9 by means of a synchronous or timing belt (or timing chain) 7.

[0030] A crank wheel is attached to the crankshaft 6, and the crank angle sensor 2 is located adjacent to the crankshaft 6. A plurality of projections 13 protrude from the outer circumference of the crank wheel.

[0031] Similarly, the cam wheel is attached to the intake camshaft 11, and the cam angle sensor 3 is located adjacent to the intake camshaft 11. A multitude of projections 14 protrude from the outer circumference of the cam wheel.

[0032] This crank wheel and cam wheel and this crank angle sensor 2 and cam angle sensor 3 are basically the same as conventional ones.

[0033] More precisely, the crank angle sensor 2 can output a pulse signal when the projection 13 on the crank wheel passes the crank angle sensor 2. The cam angle sensor 3 can output a pulse signal when the projection 14 passes the cam wheel.

[0034] The power engine ECU 51 receives the pulse signals described above and can therefore calculate a rotational frequency of the crankshaft 6 and a rotational frequency of the intake camshaft 11 based on input intervals, an input number and the like of the pulse signals.

[0035] In the embodiment of the present invention, in addition to the power engine ECU 51 described above, a body ECU (as “B-ECU”) is included. Fig. 2 described) 52, which is an electronic control unit that performs operational control for electrical devices other than the power machine 5, and the like (see Fig. 2).

[0036] The body ECU 52 and the engine ECU 51 are each powered by a vehicle battery (referred to as "BAT" in Fig. 2 described) 22 via an ignition switch (in Fig. 2 described as “IG-SW”) 21 supplied (see Fig. 2).

[0037] Fig. Figure 3 is a flowchart of a subroutine illustrating a process for processing valve phase confirmation during the starting of the internal combustion engine according to the embodiment of the present invention, which is executed by the engine ECU 51. A description of its contents is given below with regard to Fig. 3.

[0038] Similar to related techniques, it is initially assumed that the engine ECU 51, according to the embodiment of the present invention, performs a so-called cylinder determination process separately and simultaneously, and the valve phase confirmation process in parallel, when starting the internal combustion engine. Various methods are available for cylinder determination. However, there is no need to restrict the cylinder determination method to a specific method.

[0039] Under such an assumption, when the ignition switch 21 is turned on, the power supply to the engine ECU 51 begins and the VVT ​​system 1 is started with electric drive (see step S100 in Fig. 3).

[0040] Next, the valve phase is set and the valve is driven by the VVT ​​system 1 with an electric actuator (see step S200 in Fig. 3).

[0041] Before a detailed description of the processing for valve phase confirmation during the starting of the internal combustion engine according to the embodiment of the present invention, a description of an overview of the entire processing process will be given.

[0042] Compared to the related technique, the processing for valve phase confirmation during the starting of the internal combustion engine according to the embodiment of the present invention can shorten a starting time, improve the reliability of a starting, and the like, in particular by immediately confirming the valve phase of the intake valve (not illustrated) and by using the valve phase for an internal combustion engine starting control during the starting of the engine 5.

[0043] The following is a specific description of the valve phase confirmation process. First, in step S200, a target VVT angle, that is, a displacement quantity (a rotation angle), of the intake camshaft 11 is set to move the intake valve (not illustrated), in other words, to rotate the intake camshaft 11. Next, the electrically driven VVT actuator 1a moves the intake valve (not illustrated) according to the target VVT angle.

[0044] The electrically driven VVT actuator 1a is repeatedly driven several times based on this target VVT angle to eventually position the inlet valve (not illustrated) at the most delayed position as a specified endpoint.

[0045] Here, the target VVT angle is not limited to a specific value. However, as will be described below, the intake valve is driven according to the target VVT angle, and it is determined, based on a change in the output signal of the cam angle sensor 3, that the intake valve (not illustrated) has reached its most retarded position. Consequently, a relatively small angle is preferably selected for the target VVT angle.

[0046] Next, a valve phase deviation Δθ is calculated (see step S300 in Fig. 3).

[0047] Here, at a time when this step S300 is executed, the valve phase deviation Δθ is a difference between the output values ​​of the cam angle sensor 3 before and after such a time.

[0048] More precisely, for example, in the case where the most recent output value of the cam angle sensor 3 is defined as θdet(n) and the output value of the cam angle sensor 3 immediately before the acquisition of this output value θdet(n) is defined as θdet(n-1), the valve phase deviation Δθ is calculated as Δθ = θdet(n) - θdet(n-1).

[0049] Next, it is determined whether the processing for cylinder determination is complete (see step S400 in Fig. 3).

[0050] As described above as the prerequisite for the power engine ECU 51 according to the embodiment of the present invention, the processing for cylinder determination is carried out separately from the processing for valve phase confirmation based on the conventional method.

[0051] If step S400 determines that the cylinder determination processing is complete (if YES), the intake valve phase (not illustrated) (referred to below as an "intake valve phase" for simplicity) is also confirmed. Consequently, it is no longer necessary to perform the valve phase confirmation processing when starting the internal combustion engine. In this case, the valve position control is then executed when starting engine 5 based on a result of the cylinder determination processing, and ignition is initiated in engine 5 (see step S700 in...). Fig. 3).

[0052] If, on the other hand, step S400 determines that the cylinder determination process is not complete (if NO), the endpoint is determined using the valve phase deviation Δθ (see step S500 in Fig. 3).

[0053] That is, it is determined whether an absolute value of the valve phase deviation Δθ, calculated in step S300 above, is below a reference deviation θs.

[0054] This processing for determination is carried out from a perspective described below.

[0055] While the intake valve phase is changed towards the most delayed position as a final target position according to the target VVT angle, the difference between the most recent output value θdet(n) of the cam angle sensor 3 and the last output value θdet(n-1) of the cam angle sensor 3 always occurs.

[0056] In other words, the most recent output value θdet(n) is always larger than the last output value θdet(n-1), and a magnitude of the difference corresponds to the rotation angle of the intake camshaft 11 by the electrically driven VVT actuator 1a.

[0057] Once the intake valve phase reaches its most delayed position, the change in the output of the cam angle sensor 3 theoretically ceases at that output value. Consequently, the valve phase deviation Δθ is theoretically zero at that time. In reality, however, the valve phase deviation Δθ cannot always be zero due to fluctuations in the output characteristic of the cam angle sensor 3 and the like. For this reason, in the embodiment of the present invention, if the absolute value of the valve phase deviation Δθ is below the reference deviation θs, it is determined that the intake valve phase has reached its most delayed position.

[0058] Meanwhile, in step S500, if it is determined that the absolute value of the valve phase deviation Δθ is below the reference deviation θs (if YES), it is determined that the intake valve phase has reached its most delayed position as the specified endpoint. Then, the most delayed position of the intake valve phase at that time is stored and retained as a learned value of the intake valve phase in an appropriate memory area of ​​the power engine ECU 51 (step S600 in...). Fig. 3).

[0059] Next, the valve position control is executed during the starting of engine 5 based on the intake valve phase, which is confirmed as described above, and the ignition of engine 5 is started (see step S700 in Fig. 3).

[0060] Next, a description of the valve phase confirmation process during the starting of the internal combustion engine according to the embodiment of the present invention as a whole will be given with reference to schematic graphs, which are shown in Fig. 4 are illustrated.

[0061] When the ignition switch 21 is switched on (see time t1 in Fig. 4A) and the VVT ​​system 1 is electrically driven by the engine ECU 51 to move the intake valve (not illustrated) to the most retarded position, setting the target VVT angle and driving the intake valve (not illustrated) by the electrically driven VVT actuator 1a according to the target VVT angle are repeated several times (see time t2 further in Fig. 4B).

[0062] In Fig. 4B, a change in the target VVT angle and a change in the valve phase (an actual angle), detected by the cam angle sensor 3, are each indicated by a line with two dots and a dash and a solid line, respectively. The changes in both the target VVT angle and the valve phase (the actual angle) correspond to each other over a time interval from the time at which the inlet valve (not illustrated) is driven by the electrically driven VVT actuator 1a (the time t2 in Fig. 4B) until the time at which the actual angle reaches an endpoint position, (time t4 in Fig. 4B) and in a time interval from the time when the actual angle is at the endpoint position until the time when the actual angle reaches an optimal VVT phase position. Consequently, the target VVT angle and the valve phase (the actual angle) should be indicated by a single line. In Fig. However, in 4B, to facilitate understanding, the target VVT angle and the valve phase (the actual angle) are illustrated in parallel, with a small gap provided between them.

[0063] While the inlet valve (not illustrated) is repeatedly actuated by the electrically driven VVT actuator 1a according to the target VVT angle, starting begins as described above (see time t3 in Fig. 4D). In such a case, the engine speed is gradually increased (see Fig. 4E).

[0064] As described above, the inlet valve (not illustrated) is driven further by the electrically driven VVT actuator 1a according to the target VVT angle until the absolute value of the valve phase deviation Δθ is below the reference deviation θs. When it is determined that the absolute value of the valve phase deviation Δθ is below the reference deviation θs, it is then determined that the inlet valve phase has reached its most delayed position as the endpoint (see time t5 in Figure 1). Fig. 4C).

[0065] At this point, the electrically driven VVT actuator 1a, in the case where cylinder determination is not completed by the cylinder determination process, which is carried out separately from the valve phase confirmation process when starting the internal combustion engine, (see time t6 in Fig. 4F) the valve position control based on the intake valve phase, which is confirmed by the valve phase confirmation processing during engine start-up, and ignition in engine 5 is initiated (see time t7 in Fig. 4G).

[0066] The process for confirming the valve phase during the starting of the internal combustion engine according to the embodiment of the present invention is applied as described above. Compared to the case in which the valve position during starting is confirmed by the conventional process for cylinder determination, the possibilities for immediate confirmation of the valve position are consequently increased and the starting time is further reduced.

[0067] Furthermore, the possibilities for ensuring sufficient time to actuate the intake valve from confirmation of the valve position until the optimal valve phase for starting an engine are increased, thus guaranteeing efficient combustion during starting. Compared to related technologies, the incidence of misfires and abnormal combustion is therefore reduced.

[0068] Since the start-up time can be shortened, emissions of unburned hydrocarbons (HC) and harmful gases are also reduced. Shortening the start-up time allows the catalyst to be heated immediately. Consequently, a reduction in harmful gas emissions can be expected due to the immediate heating of the catalyst.

[0069] The present invention can be applied to the vehicle for which immediate confirmation of the valve position when starting the internal combustion engine is desired.

Claims

[1] Method for confirming a valve phase during the starting of an internal combustion engine, wherein the method confirms a valve phase during the starting of an internal combustion engine having a variable valve timing system configured to adjust the valve phase of the internal combustion engine, the method comprising: Shifting the valve phase to a most delayed position by the variable valve timing system when starting the internal combustion engine; successively determining whether a valve phase deviation, i.e. a difference between output values ​​of a cam angle sensor at a consecutive time, is below a specified reference deviation; Confirming the valve phase, that the valve phase has reached the most delayed position, in the case where the valve phase deviation is below the reference deviation; Using the valve phase for starting control of the internal combustion engine; wherein the system is configured with variable valve timing to allow adjustment of the valve phase by electrical actuation, and is used to adjust an inlet valve phase; further showing the procedure: Terminating a series of processing to confirm the valve phase in the case where the valve phase is not confirmed at a time when a cylinder determination is completed during the processing for cylinder determination, which is performed separately. [2] Vehicle operating control configured to perform operating control for an internal combustion engine using an electronic control unit, wherein the internal combustion engine has a variable valve timing system configured to adjust the valve phase of the internal combustion engine, wherein The electronic control unit is configured to: shift the valve phase to a most delayed position by the variable valve timing system when starting the internal combustion engine; successively determine whether a valve phase deviation, that is, a difference between output values ​​of a cam angle sensor at a consecutive time, is below a specified reference deviation; confirm that the valve phase has reached the most delayed position if the valve phase deviation is below the reference deviation; and use the valve phase for starting control of the internal combustion engine. where the system is configured with variable valve timing to allow adjustment of the valve phase by electrical actuation, and is used to adjust an inlet valve phase, the electronic control unit is configured to: to be able to perform a cylinder determination process for the internal combustion engine separately; and to terminate a series of processes to confirm the valve phase in the event that the valve phase is not confirmed at a time when a cylinder determination process is completed during the cylinder determination process.

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