Motor control device and motor control method

Abstract

According to the present invention, a microcomputer of a VVT controller rotationally drives an electric motor of a VVT mechanism, which is provided with a stopper that regulates the rotation angle, through speed feedback control. At this time, when the absolute value of the deviation between a target rotation speed and the actual rotation speed of the electric motor remains within a predetermined range for a predetermined time, the microcomputer of the VVT controller determines that the rotation angle of a rotating body is being regulated by the stopper. When the microcomputer of the VVT controller determines that the rotation angle of the rotating body is being regulated by the stopper, the microcomputer of the VVT controller limits the current supplied to the electric motor.

Description

[Technical Field]

[0001] The present invention relates to a motor control device and a control method for driving a rotor provided with a stopper that restricts the rotation angle by speed feedback control. [Background technology]

[0002] A variable valve timing (VVT) mechanism such as that described in Japanese Patent Laid-Open Publication No. 2018-123716 (Patent Document 1) is known as an example of a controlled device equipped with a mechanical stopper that restricts the rotation angle of a rotor driven by a motor. In a VVT mechanism, the valve timing of at least one of the intake valve and the exhaust valve is changed by changing the relative rotation angle of a camshaft with respect to the crankshaft using a motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-123716 Summary of the Invention [Problem to be solved by the invention]

[0004] In the control of a VVT mechanism equipped with a stopper, for example, a process is executed in which a rotating body driven by a motor is pressed against a mechanical stopper in order to learn a reference angle for valve timing. If the accuracy of learning the reference angle is insufficient when this learning process is executed, it will not be possible to determine that the rotating body is pressed against the stopper, and an excessive current will be supplied to the electric motor in an attempt to rotate the rotating body to the target angle.

[0005] Therefore, an object of the present invention is to provide a motor control device and a motor control method that prevent excessive current from being supplied to a motor that rotates a rotor using speed feedback control when the rotation angle of the rotor is restricted by a mechanical stopper. [Means for solving the problem]

[0006] The motor control device rotates a rotor equipped with a stopper that restricts the rotation angle by speed feedback control. At this time, when the absolute value of the deviation between the target rotation speed of the motor and its actual rotation speed remains equal to or greater than a predetermined lower limit and equal to or less than a predetermined upper limit for a predetermined period of time, the motor control device: It is determined that the rotation angle of the rotor is restricted by the stopper, Limits the current supplied to the motor. [Effects of the Invention]

[0007] According to the present invention, when the rotation angle of the rotating body is restricted by a mechanical stopper, it is possible to prevent an excessive current from being supplied to the motor that rotates the rotating body by speed feedback control. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram illustrating an example of an engine system mounted on a vehicle. [Figure 2] FIG. 2 is a vertical cross-sectional view showing an example of a VVT mechanism. [Figure 3] 3 is a cross-sectional view taken along the line AA in FIG. 2. [Figure 4] 3 is a cross-sectional view of FIG. 2 taken along line B-B. [Figure 5] FIG. 1 is a diagram for explaining a defect in the prior art. [Figure 6] 4 is a flowchart showing an example of a VVT control process. [Figure 7] 4 is a flowchart showing an example of a VVT control process. [Figure 8] 4 is a flowchart showing an example of a VVT control process. [Figure 9]4 is a flowchart showing an example of a VVT control process. [Figure 10] 10A and 10B are explanatory diagrams showing a problem that occurs when a current limit value is inappropriate. [Figure 11] 10A and 10B are diagrams illustrating a method for optimizing a current limit value and the effects thereof. [Figure 12] 10A and 10B are diagrams illustrating the effect of limiting the current to the electric motor. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an example of an engine system mounted on a vehicle to which a motor control device according to this embodiment can be applied.

[0010] An engine 10 mounted on a vehicle such as an automobile is, for example, an in-line four-cylinder gasoline engine. An intake air flow sensor 14 is attached to a predetermined location of an intake pipe 12 that introduces intake air (intake air) into each cylinder. The intake air flow sensor 14 detects an intake air flow rate Q, which is one example of the load on the engine 10. For example, a hot-wire flow meter such as an air flow meter can be used as the intake air flow rate sensor 14. Note that the load on the engine 10 is not limited to the intake air flow rate Q, and can also be any state quantity closely related to torque, such as intake negative pressure, boost pressure, throttle opening, or accelerator opening.

[0011] An intake port 18, which introduces intake air into the combustion chamber 16 of each cylinder, is provided with an intake valve 20 that opens and closes the end opening facing the combustion chamber 16. A fuel injection valve 22 that injects fuel toward the rear surface of the intake valve 20 is attached to a predetermined location of the intake port 18, located upstream of the intake valve 20. When a magnetic attraction force is generated by energizing an electromagnetic coil, the fuel injection valve 22 lifts a valve element biased by a spring in the valve closing direction, opening a nozzle hole at the tip to inject fuel. Fuel adjusted to a predetermined pressure is supplied to the fuel injection valve 22 so that the amount of fuel injected is approximately proportional to the duration the nozzle hole is open. Note that the fuel injection valve 22 is not limited to a configuration that injects fuel toward the rear surface of the intake valve 20's head, but may also be a configuration that injects fuel directly into the combustion chamber 16, or a configuration that combines both.

[0012] Fuel injected from the nozzle hole of the fuel injection valve 22 passes through the gap between the end opening of the intake port 18 and the intake valve 20 and is introduced into the combustion chamber 16 together with the intake air, and is ignited and burned by spark ignition from the spark plug 24. As a result, the combustion pressure pushes the piston 26 toward the crankshaft (not shown), thereby driving the crankshaft to rotate.

[0013] An exhaust port 28, which leads exhaust gas out of the combustion chamber 16, is provided with an exhaust valve 30 that opens and closes the end opening facing the combustion chamber 16. When the exhaust valve 30 opens the end opening of the exhaust port 28, the exhaust gas passes through a gap between the end opening of the exhaust port 28 and the exhaust valve 30 and is discharged into an exhaust pipe 32. A catalytic converter 34 is attached to a predetermined location in the exhaust pipe 32. Harmful substances contained in the exhaust are purified by the catalytic converter 34 into harmless components, and then released into the atmosphere from the end opening of the exhaust pipe 32. Here, the catalytic converter 34 can be, for example, a three-way catalyst that simultaneously purifies CO (carbon monoxide), HC (hydrocarbons), and NOx (nitrogen oxides) contained in the exhaust gas.

[0014] An electric VVT mechanism 100 is attached to the end of the intake camshaft 36, which drives the intake valve 20 to open and close, thereby changing the relative rotation angle of the intake camshaft 36 with respect to the crankshaft, thereby changing the valve timing of the intake valve 20. The VVT mechanism 100 is not limited to being attached to the intake valve 20, but may be attached to at least one of the intake valve 20 and the exhaust valve 30. Details of the VVT mechanism 100 will be described later.

[0015] In addition to the intake air flow rate sensor 14, a water temperature sensor 38, an engine rotation speed sensor 40, a crank angle sensor 42, a cam angle sensor 44, and a motor rotation speed sensor 46 are attached to predetermined locations in the engine system. The water temperature sensor 38 detects the coolant temperature (water temperature) Tw of the engine 10. The engine rotation speed sensor 40 detects the rotation speed Ne of the engine 10. The crank angle sensor 42 detects the rotation angle θ of the crankshaft from a reference position. CRK The cam angle sensor 44 detects the rotation angle θ of the intake camshaft 36 from the reference position. CAM Motor rotation speed sensor 46 detects the rotation speed Nm of the output shaft of the electric motor (details of which will be described later) of VVT mechanism 100. In the following description, the rotation speed of the output shaft of the electric motor will be abbreviated as the rotation speed of the electric motor.

[0016] The output signals of the intake air flow rate sensor 14, water temperature sensor 38, engine speed sensor 40, crank angle sensor 42, cam angle sensor 44, and motor speed sensor 46 are input to an engine control module (ECM) 200, which incorporates a microcomputer (not shown). The engine control module 200 reads the intake air flow rate Q and the engine speed Ne from the intake air flow rate sensor 14 and the engine speed sensor 40, respectively, and calculates a basic fuel injection amount according to the engine operating conditions based on these. The engine control module 200 also reads the water temperature Tw from the water temperature sensor 38 and calculates a fuel injection amount by correcting the basic fuel injection amount based on the water temperature Tw, etc. The engine control module 200 then outputs activation signals to the fuel injector 22 and the spark plug 24 at timings according to the engine operating conditions, causing the fuel injector 22 to inject fuel according to the fuel injection amount and the spark plug 24 to ignite and burn the fuel-air mixture. At this time, the engine control module 200 reads the air-fuel ratio from an air-fuel ratio sensor (not shown) and feedback controls the fuel injector 22 so that the air-fuel ratio in the exhaust gas approaches the target air-fuel ratio.

[0017] In addition to controlling the fuel injectors 22 and the spark plugs 24, the engine control module 200 reads the intake air flow rate Q and the rotational speed Ne from the intake air flow rate sensor 14 and the engine rotational speed sensor 40, respectively, and calculates a target angle of the VVT mechanism 100 according to the engine operating state. The engine control module 200 also multiplies the rotational speed Ne by 1 / 2 to calculate the rotational speed Nc of the intake camshaft 36 (Nc = Ne × 1 / 2), and reads the rotational speed Nm from the motor rotational speed sensor 46. The engine control module 200 then calculates a target rotational speed Nt of the electric motor according to the rotational speed Nc of the intake camshaft 36, the rotational speed Nm of the electric motor, and the reduction ratio of the VVT mechanism 100, so that the VVT mechanism 100 approaches the target angle. The engine control module 200 then transmits the target rotational speed Nt of the electric motor to a VVT controller 250, which has a built-in microcomputer (not shown), via a well-known in-vehicle network such as a CAN (Controller Area Network). Here, an output signal of a motor rotation speed sensor 46 that detects the rotation speed Nm of the electric motor is input to the VVT controller 250, similar to the engine control module 200. The VVT controller 250 is an example of a motor control device.

[0018] VVT controller 250 receives target rotation speed Nt of the electric motor, reads the actual rotation speed (actual rotation speed) Nm of the electric motor from motor rotation speed sensor 46, and performs feedback control of the current supplied to the electric motor so that actual rotation speed Nm approaches target rotation speed Nt. In short, VVT controller 250 controls the current supplied to the electric motor of VVT mechanism 100 by speed feedback control.

[0019] 2 to 4 show an example of the VVT mechanism 100. Note that the VVT mechanism 100 shown in Figures 2 to 4 is merely an example, and any VVT mechanism known to those skilled in the art may be used as long as it is provided with a mechanical stopper that restricts the rotation angle of a rotor that is rotationally driven by an electric motor.

[0020] As shown in FIG. 2, the VVT mechanism 100 includes a timing sprocket (cam sprocket) 102, a cover member 104, and a phase change mechanism 106. The timing sprocket 102 is rotated by the crankshaft of the engine 10 via a timing chain 108. The timing sprocket 102 then rotates the intake camshaft 36 that is integrated with the timing sprocket 102. The cover member 104 is fastened with bolts 112 to a chain cover 110, which is a fixed structure of the engine 10, on a side distal to the timing sprocket 102 relative to the intake camshaft 36. The phase change mechanism 106 is disposed between the timing sprocket 102 and the intake camshaft 36 and changes the relative rotation angle of the timing sprocket 102 with respect to the intake camshaft 36. Here, the timing sprocket 102 is an example of a rotating body.

[0021] Timing sprocket 102 is disposed rotatably relative to the outer peripheral surface of the end of intake camshaft 36 via ball bearing 114. An annular member 116, having wavy internal teeth 116A (see FIG. 3) formed on its inner circumference, and an annular plate 118 are fastened by bolts 120 to a side surface of the outer periphery of timing sprocket 102 that is located distal to intake camshaft 36. In addition, as shown in FIG. 4, an arc-shaped stopper protrusion 102A is formed on part of the inner peripheral surface of timing sprocket 102 over a predetermined length in the circumferential direction.

[0022] A cylindrical housing 126 extending distally from the intake camshaft 36 is fastened to the outer periphery of the distal side of the plate 118 with bolts 128 so as to cover the components of the reducer 122 of the phase change mechanism 106 and the electric motor 124. The housing 126 is made of a non-ferrous metal and functions as a yoke. A holding portion 126A in the shape of an annular plate is integrally connected to the distal end surface of the housing 126. The housing 126 is covered by the cover member 104, which is disposed further distally than the housing 126, with at least a predetermined distance therebetween.

[0023] A driven member 130, which is a driven rotor, is fastened to the end of intake camshaft 36 by cam bolt 132. In addition, an arc-shaped stopper groove 36A is formed over a predetermined length in the circumferential direction on part of the outer circumferential surface of the tip end of intake camshaft 36, as shown in Figure 4. Stopper protrusion 102A of timing sprocket 102 fits into this groove for relative rotation. Here, stopper protrusion 102A of timing sprocket 102 and stopper groove 36A of intake camshaft 36 form a stopper.

[0024] When timing sprocket 102 rotates relative to intake camshaft 36 and stopper protrusion 102A abuts against the inner surface of stopper groove 36A, timing sprocket 102 is prevented from rotating relative to intake camshaft 36. This defines the maximum advance position and maximum retard position of timing sprocket 102 relative to intake camshaft 36, thereby limiting the variable range of valve timing for intake valve 20.

[0025] 2 and 3, the driven member 130 is made of an iron-based metal and includes a disk portion 130A located proximal to the intake camshaft 36 and a cylindrical portion 130B located distal to the intake camshaft 36. A ring-shaped protrusion 130C having substantially the same diameter as the intake camshaft 36 is formed integrally with the disk portion 130A, into which a portion of the inner ring of the ball bearing 114 is fitted. In addition, a cage 136 that holds a plurality of rollers 134 is formed integrally with the outer periphery of the disk portion 130A.

[0026] The phase change mechanism 106 includes an electric motor 124 arranged concentrically with the intake camshaft 36, and a reducer 122 that transmits the rotational speed of the electric motor 124 to the intake camshaft 36 while reducing the rotational speed.

[0027] The electric motor 124 includes a housing 126 that rotates integrally with the timing sprocket 102, a motor shaft 138 that is rotatably disposed within the housing 126, a pair of permanent magnets 140, 142 fixed to the inner circumferential surface of the housing 126, and a stator 144 that is fixed to a holding portion 126A of the housing 126. The motor shaft 138 is cylindrical and functions as an armature. An iron-core rotor 146 with multiple poles is fixed to the outer periphery of the motor shaft 138 at approximately the center. An electromagnetic coil 148 is wound around the iron-core rotor 146.

[0028] The motor shaft 138 is disposed so as to be rotatable relative to the outer periphery of the cam bolt 132 and the outer periphery of the cylindrical portion 130B of the driven member 130 via a ball bearing 150 and a needle bearing 152. A cylindrical eccentric shaft portion 154 that constitutes a part of the reducer 122 is integrally formed on the proximal end of the motor shaft 138.

[0029] The reducer 122 is configured to include an eccentric shaft portion 154 that performs eccentric rotational motion, a ball bearing 156 arranged on the outer periphery of the eccentric shaft portion 154, rollers 134 arranged on the outer periphery of the ball bearing 156, a cage 136 that holds the rollers 134 in the rolling direction while allowing them to move in the radial direction, and a driven member 130 that is integrated with the cage 136. The axis of a cam surface formed on the outer periphery of the eccentric shaft portion 154 is slightly eccentric in the radial direction from the axis X of the motor shaft 138. Here, the ball bearing 156, the rollers 134, etc. function as a planetary meshing portion.

[0030] Furthermore, rollers 134 are constantly in contact with the outer peripheral surface of the outer ring of ball bearing 156. Furthermore, an annular gap 158 is formed on the outer periphery of ball bearing 156, and this gap 158 allows the entire ball bearing 156 to move radially in accordance with the eccentric rotation of eccentric shaft portion 154, in other words, to be eccentric. Each roller 134 moves radially in accordance with the eccentric movement of ball bearing 156 and fits into internal teeth 116A of annular member 116, and is configured to oscillate radially while being guided circumferentially by cage 136.

[0031] Next, the operation of the VVT mechanism 100 will be described. When the crankshaft of the engine 10 rotates, the timing sprocket 102 is rotated via the timing chain 108, and the resulting rotational force synchronously rotates the electric motor 124 via the annular member 116, the plate 118, and the housing 126. Meanwhile, the rotational force of the annular member 116 is transmitted to the intake camshaft 36 via the roller 134, the cage 136, and the driven member 130. This rotates the intake camshaft 36, and the cam formed thereon opens and closes the intake valve 20.

[0032] To change the relative rotation angle of the intake camshaft 36 with respect to the crankshaft, i.e., to change the valve timing of the intake valves 20, the electromagnetic coil 148 is energized to operate the electric motor 124. When the electric motor 124 is operating, the motor torque is transmitted to the intake camshaft 36 via the reducer 122. That is, when the eccentric shaft portion 154 rotates eccentrically in conjunction with the rotation of the motor shaft 138, each roller 134 is guided radially by the cage 136 and moves over one internal tooth 116A of the annular member 116, rolling onto the adjacent internal tooth 116A, with each rotation of the motor shaft 138. The rollers 134 then rotate in the circumferential direction, repeatedly repeating this process. As the rollers 134 rotate, the rotation of the motor shaft 138 is transmitted to the driven member 130 at a reduced speed. The reduction ratio when the rotation of the motor shaft 138 is transmitted to the driven member 130 can be set arbitrarily depending on the number of rollers 134 and the like.

[0033] As a result, the intake camshaft 36 rotates forward or backward relative to the timing sprocket 102, changing the angle of relative rotation, thereby changing the opening and closing timing of the intake valve 20 to the advance or retard side.

[0034] At this time, the forward and reverse relative rotation of the intake camshaft 36 with respect to the timing sprocket 102 is restricted by the stopper protrusion 102A abutting against the inner surface of the stopper groove 36A. That is, the driven member 130 rotates relative to the timing sprocket 102 in the same direction as the rotation of the timing sprocket 102 in conjunction with the eccentric rotation of the eccentric shaft portion 154, causing the stopper protrusion 102A to abut against one side surface of the stopper groove 36A, restricting further rotation. As a result, the relative rotation angle of the intake camshaft 36 with respect to the timing sprocket 102 is changed to the maximum advanced angle. On the other hand, the driven member 130 rotates relative to the timing sprocket 102 in the direction opposite to the rotation direction of the timing sprocket 102, causing the stopper protrusion 102A to abut against the other side surface of the stopper groove 36A, restricting further rotation. As a result, the relative rotation angle of the intake camshaft 36 with respect to the timing sprocket 102 is changed to the maximum retarded angle.

[0035] The mechanical stopper of VVT mechanism 100 is used, for example, to learn the reference phase of the valve timing, to set the valve timing to the most retarded phase when engine 10 is stopped in preparation for the next start, or to set the valve timing to the most advanced phase while engine 10 is running. When electric motor 124 of VVT mechanism 100 is rotationally driven by speed feedback control, if the reference angle is not learned accurately, it may be impossible to determine that the stopper is restricting the relative rotation of timing sprocket 102 with respect to intake camshaft 36. In this case, VVT controller 250 attempts to rotate timing sprocket 102 relative to intake camshaft 36 to the stopper activation position. Then, as shown in FIG. 5, VVT controller 250 gradually increases the current value supplied to electric motor 124 to bring the actual rotational speed of electric motor 124 closer to the target rotational speed, ultimately supplying an excessive current to electric motor 124.

[0036] Therefore, when the absolute value of the deviation between target rotational speed Nt and actual rotational speed Nm of electric motor 124 remains within a predetermined range for a predetermined period of time, VVT controller 250 determines that stopper protrusion 102A of timing sprocket 102 is contacting the inner surface of stopper groove 36A of intake camshaft 36. If VVT controller 250 determines that stopper protrusion 102A is contacting the inner surface of stopper groove 36A, it limits the current supplied to electric motor 124 to prevent excessive current from being supplied to electric motor 124. This process will be described in detail below.

[0037] 6 to 9 show an example of VVT control processing that is repeatedly executed at predetermined time intervals by the microcomputer of VVT controller 250 when VVT controller 250 is started. The microcomputer of VVT controller 250 executes the VVT control processing in accordance with an application program stored in a nonvolatile memory such as a flash ROM (Read Only Memory). A determination flag that holds the result of determining whether or not the stopper is being pressed is reserved in a variable area reserved in advance in a volatile memory such as a RAM (Random Access Memory) of the microcomputer. Here, the determination flag is selectively set to either "TRUE (e.g., 1)," which indicates that the stopper is being pressed, or "FALSE (e.g., 0)," which indicates that the stopper is not being pressed, with its initial value being "FALSE."

[0038] In step 10 (abbreviated as "S10" in FIG. 6, and the same applies below), the microcomputer of the VVT controller 250 calculates the speed deviation between the target rotational speed and the actual rotational speed of the electric motor 124. Specifically, the microcomputer of the VVT controller 250 reads the rotational speed Nm of the electric motor 124 from the motor rotational speed sensor 46 and calculates the speed deviation by subtracting the rotational speed Nm from the target rotational speed Nt received from the engine control module 200 (speed deviation = target rotational speed Nt - rotational speed Nm). Note that the rotational speed Nm detected by the motor rotational speed sensor 46 represents the actual rotational speed of the electric motor 124, and therefore will be referred to as the "actual rotational speed Nm" in the following description. Furthermore, since the rotational speed Ne of the engine 10 is closely related to the actual rotational speed Nm of the electric motor 124, the rotational speed Ne of the engine 10 may also be considered to be the actual rotational speed Nm of the electric motor 124.

[0039] In step 11, the microcomputer of VVT controller 250 calculates a current command value to be supplied to electric motor 124 according to the speed deviation calculated in step 10 and the current value (actual current value) of the current actually supplied to electric motor 124.

[0040] In step 12, the microcomputer of VVT controller 250 determines whether the determination flag is "FALSE," in other words, whether the stopper is being pressed. If the microcomputer of VVT controller 250 determines that the determination flag is "FALSE," that is, that the stopper is not being pressed (Yes), it proceeds to step 13. On the other hand, if the microcomputer of VVT controller 250 determines that the determination flag is "TRUE," that is, that the stopper is being pressed (No), it proceeds to step 17.

[0041] In step 13, the microcomputer of VVT controller 250 determines whether the absolute value of the speed deviation is equal to or greater than a predetermined lower limit and equal to or less than a predetermined upper limit. Here, the predetermined lower limit and the predetermined upper limit are parameters for determining whether the stopper is being pressed, and can be determined appropriately taking into consideration, for example, the operating characteristics of VVT mechanism 100. If the microcomputer of VVT controller 250 determines that the absolute value of the speed deviation is equal to or greater than the predetermined lower limit and equal to or less than the predetermined upper limit (Yes), it proceeds to step 14. On the other hand, if the microcomputer of VVT controller 250 determines that the absolute value of the speed deviation is not equal to or greater than the predetermined lower limit and equal to or less than the predetermined upper limit, in other words, if it determines that the absolute value of the speed deviation is less than the predetermined lower limit or greater than the predetermined upper limit (No), it proceeds to step 19.

[0042] In step 14, the microcomputer of VVT controller 250 determines, for example, using a timer function, whether the state in which the absolute value of the speed deviation is equal to or greater than a predetermined lower limit and equal to or less than a predetermined upper limit has continued for a predetermined time. Here, the predetermined time is another parameter for determining whether the stopper is being pressed, and can be determined appropriately taking into account, for example, the time it takes for the stopper to be pressed. If the microcomputer of VVT controller 250 determines that the state in which the absolute value of the speed deviation is equal to or greater than the predetermined lower limit and equal to or less than the predetermined upper limit has continued for the predetermined time (Yes), the microcomputer of VVT controller 250 proceeds to step 15. On the other hand, if the microcomputer of VVT controller 250 determines that the state in which the absolute value of the speed deviation is equal to or greater than the predetermined lower limit and equal to or less than the predetermined upper limit has not continued for the predetermined time (No), the microcomputer proceeds to step 19.

[0043] In step 15, the microcomputer of the VVT controller 250 stores the actual current value of the current being supplied to the electric motor 124 in a variable area reserved in advance in the volatile memory.

[0044] In step 16, the microcomputer of the VVT controller 250 sets the determination flag to "TRUE," that is, determines that the stopper is being pressed.

[0045] In step 17, the microcomputer of VVT controller 250 determines whether the sign of the speed deviation has reversed, specifically whether the sign of the speed deviation in the previous control cycle is different from the sign of the speed deviation in the current control cycle. If the microcomputer of VVT controller 250 determines that the sign of the speed deviation has reversed (Yes), it proceeds to step 18. On the other hand, if the microcomputer of VVT controller 250 determines that the sign of the speed deviation has not reversed (No), it proceeds to step 19.

[0046] In step 18, the microcomputer of the VVT controller 250 sets the determination flag to "FALSE," that is, determines that the pressure against the stopper has been released. After that, the microcomputer of the VVT controller 250 proceeds to step 19.

[0047] In step 19, the microcomputer of VVT controller 250 determines whether the determination flag is "TRUE," i.e., whether it has determined that the stopper is being pressed. If the microcomputer of VVT controller 250 determines that the determination flag is "TRUE" (Yes), it proceeds to step 20. On the other hand, if the microcomputer of VVT controller 250 determines that the determination flag is not "TRUE," i.e., that the stopper is not being pressed (No), it proceeds to step 45.

[0048] In step 20, the microcomputer of VVT controller 250 determines whether the speed deviation calculated in step 10 is equal to or greater than 0, in other words, whether there is a push toward the advance angle side. If the microcomputer of VVT controller 250 determines that the speed deviation is equal to or greater than 0 (Yes), it proceeds to step 21. On the other hand, if the microcomputer of VVT controller 250 determines that the speed deviation is not equal to or greater than 0, in other words, there is a push toward the retard angle side (No), it proceeds to step 33.

[0049] In step 21, the microcomputer of VVT controller 250 determines whether the determination flag was "FALSE" in the previous control cycle, in other words, whether or not the stopper was not pressed in the previous control cycle. If the microcomputer of VVT controller 250 determines that the determination flag was "FALSE" in the previous control cycle (Yes), it proceeds to step 22. On the other hand, if the microcomputer of VVT controller 250 determines that the determination flag was not "FALSE" in the previous control cycle, in other words, that the stopper was pressed in the previous control cycle (No), it proceeds to step 27.

[0050] In step 22, the microcomputer of VVT controller 250 determines whether the determination flag is "TRUE" in the current control cycle, in other words, whether the stopper is being pressed in the current control cycle. If the microcomputer of VVT controller 250 determines that the determination flag is "TRUE" in the current control cycle (Yes), it proceeds to step 23. On the other hand, if the microcomputer of VVT controller 250 determines that the determination flag is not "TRUE" in the current control cycle, in other words, that the stopper is not being pressed (No), it proceeds to step 27.

[0051] In step 23, the microcomputer of VVT controller 250 determines whether the learned value on the advance angle side is equal to or less than the actual current value when it is determined that the brake is being pressed against the stopper. If the microcomputer of VVT controller 250 determines that the learned value on the advance angle side is equal to or less than the actual current value (Yes), it proceeds to step 24. On the other hand, if the microcomputer of VVT controller 250 determines that the learned value on the advance angle side is not equal to or less than the actual current, that is, that the learned value on the advance angle side is greater than the actual current value (No), it proceeds to step 26.

[0052] In step 24, the microcomputer of the VVT controller 250 sets the current limit value, which is a parameter for limiting the current supplied to the electric motor 124, to the actual current value when it is determined that the electric motor 124 is being pressed against the stopper.

[0053] In step 25, the microcomputer of VVT controller 250 sets the learned value on the advance angle side to the actual current value when it is determined that the brake is being pressed against the stopper. After that, the microcomputer of VVT controller 250 advances the process to step 27.

[0054] In step 26, the microcomputer of VVT controller 250 adopts the learned value on the advance angle side as the current limit value. Thereafter, the microcomputer of VVT controller 250 advances the process to step 27.

[0055] In step 27, the microcomputer of VVT controller 250 reads the actual rotation speed Nm of electric motor 124 from motor rotation speed sensor 46 and determines whether this is 0 or not, in other words, whether the electric motor 124 is being pressed against the stopper when the engine 10 is stopped. If the microcomputer of VVT controller 250 determines that the actual rotation speed Nm of electric motor 124 is 0 (Yes), it proceeds to step 28. On the other hand, if the microcomputer of VVT controller 250 determines that the actual rotation speed Nm of electric motor 124 is not 0 (No), it proceeds to step 31.

[0056] In step 28, the microcomputer of VVT controller 250 increases the current limit value by a predetermined value. That is, the microcomputer of VVT controller 250 takes into consideration, for example, that the cam torque of intake camshaft 36 when engine 10 is stopped may prevent VVT mechanism 100 from operating at the current current limit value, and increases the current limit value by the predetermined value.

[0057] In step 29, the microcomputer of VVT controller 250 determines whether the current limit value is equal to or greater than a predetermined current upper limit value, in other words, whether the intake camshaft 36 is being pressed against the stopper against the cam torque. If the microcomputer of VVT controller 250 determines that the current limit value is equal to or greater than the current upper limit value (Yes), it proceeds to step 30. On the other hand, if the microcomputer of VVT controller 250 determines that the current limit value is not equal to or greater than the current upper limit value, in other words, whether the intake camshaft 36 is not being pressed against the stopper against the cam torque (No), it proceeds to step 31.

[0058] In step 30, the microcomputer of the VVT controller 250 turns off the power supply to the electric motor 124. In short, the microcomputer of the VVT controller 250 determines that the engine 10 has been pressed against the stopper during the process of stopping the engine 10, and stops the supply of current to the electric motor 124 in order to reduce unnecessary power consumption, for example.

[0059] In step 31, the microcomputer of VVT controller 250 determines whether the stopper is still being pressed. Specifically, the microcomputer of VVT controller 250 recalculates the current speed deviation and determines whether the absolute value of the value obtained by subtracting the current speed deviation from the speed deviation calculated in step 10 is equal to or less than a predetermined deviation, in other words, whether the stopper is still being pressed according to the two speed deviations. If the microcomputer of VVT controller 250 determines that the stopper is still being pressed (Yes), it proceeds to step 45. On the other hand, if the microcomputer of VVT controller 250 determines that the stopper is not still being pressed (No), it proceeds to step 32.

[0060] In step 32, the microcomputer of VVT controller 250 increases the current limit value by a predetermined value. In short, the microcomputer of VVT controller 250 takes into consideration that the set current limit value cannot keep up with the increase in engine speed of engine 10 when pressing against the advance side stopper, and increases the current limit value by a predetermined value to address this. Thereafter, the microcomputer of VVT controller 250 proceeds to step 45.

[0061] In step 33, the microcomputer of the VVT controller 250 reads the actual rotational speed Nm of the electric motor 124 from the motor rotational speed sensor 46 and determines whether this is equal to or less than a predetermined rotational speed. In other words, the microcomputer of the VVT controller 250 determines whether the rotational speed of the intake camshaft 36, which is closely related to the actual rotational speed Nm of the electric motor 124 when pressing against the retard side stopper, is equal to or less than a predetermined value. If the microcomputer of the VVT controller 250 determines that the actual rotational speed Nm of the electric motor 124 is equal to or less than the predetermined rotational speed (Yes), it proceeds to step 34. On the other hand, if the microcomputer of the VVT controller 250 determines that the actual rotational speed Nm of the electric motor 124 is not equal to or less than the predetermined rotational speed, in other words, if it determines that the actual rotational speed Nm of the electric motor 124 is greater than the predetermined rotational speed (No), it proceeds to step 35.

[0062] In step 34, the microcomputer of VVT controller 250 turns off the power supply to electric motor 124. In short, when the rotational speed of intake camshaft 36 is equal to or lower than a predetermined value, the cam torque of intake camshaft 36 can press the electric motor 124 against the retard side stopper, so the microcomputer of VVT controller 250 stops the supply of current to electric motor 124 to reduce unnecessary power consumption. Thereafter, the microcomputer of VVT controller 250 proceeds to step 35.

[0063] In step 35, the microcomputer of VVT controller 250 determines whether the determination flag in the previous control cycle was "FALSE," in other words, whether the vehicle was not pressed against the stopper in the previous control cycle. If the microcomputer of VVT controller 250 determines that the determination flag in the previous control cycle was "FALSE" (Yes), it proceeds to step 36. On the other hand, if the microcomputer of VVT controller 250 determines that the determination flag in the previous control cycle was not "FALSE," in other words, whether the vehicle was pressed against the stopper in the previous control cycle (No), it proceeds to step 41.

[0064] In step 36, the microcomputer of VVT controller 250 determines whether the determination flag for the current control cycle is "TRUE," in other words, whether the stopper is being pressed against the stopper in the current control cycle. If the microcomputer of VVT controller 250 determines that the determination flag for the current control cycle is "TRUE" (Yes), it proceeds to step 37. On the other hand, if the microcomputer of VVT controller 250 determines that the determination flag for the current control cycle is not "TRUE," in other words, whether the stopper is not being pressed against the stopper in the current control cycle (No), it proceeds to step 41.

[0065] In step 37, the microcomputer of VVT controller 250 determines whether the learned value on the retard angle side is equal to or less than the actual current value when it is determined that the brake is being pressed against the stopper. If the microcomputer of VVT controller 250 determines that the learned value on the retard angle side is equal to or less than the actual current value (Yes), it proceeds to step 38. On the other hand, if the microcomputer of VVT controller 250 determines that the learned value on the retard angle side is not equal to or less than the actual current value, that is, is greater than the actual current value (No), it proceeds to step 40.

[0066] In step 38, the microcomputer of the VVT controller 250 sets the current limit value to the actual current value when it is determined that the stopper is being pressed.

[0067] In step 39, the microcomputer of VVT controller 250 sets the retard side learning value to the actual current value when it is determined that the stopper is being pressed.

[0068] In step 40, the microcomputer of the VVT controller 250 adopts the learned value on the retard side as the current limit value. Thereafter, the microcomputer of the VVT controller 250 advances the process to step 41.

[0069] In step 41, the microcomputer of VVT controller 250 reads the actual rotation speed Nm of electric motor 124 from motor rotation speed sensor 46 and determines whether this is 0, in other words, whether the electric motor 124 is being pressed against a stopper when the engine 10 is stopped. If the microcomputer of VVT controller 250 determines that the actual rotation speed Nm of electric motor 124 is 0 (Yes), it proceeds to step 42. On the other hand, if the microcomputer of VVT controller 250 determines that the actual rotation speed Nm of electric motor 124 is not 0 (No), it proceeds to step 45.

[0070] In step 42, the microcomputer of VVT controller 250 increases the current limit value by a predetermined value. That is, the microcomputer of VVT controller 250 increases the current limit value by the predetermined value, taking into consideration that, for example, the cam torque of intake camshaft 36 when engine 10 is stopped may prevent VVT mechanism 100 from operating at the current current limit value.

[0071] In step 43, the microcomputer of VVT controller 250 determines whether the current limit value is equal to or greater than a predetermined current upper limit value, in other words, whether the intake camshaft 36 is being pressed against the stopper against the cam torque. If the microcomputer of VVT controller 250 determines that the current limit value is equal to or greater than the current upper limit value (Yes), it proceeds to step 44. On the other hand, if the microcomputer of VVT controller 250 determines that the current limit value is not equal to or greater than the current upper limit value, in other words, whether the intake camshaft 36 is not being pressed against the stopper against the cam torque (No), it proceeds to step 45.

[0072] In step 44, the microcomputer of the VVT controller 250 turns off the power supply to the electric motor 124. In short, the microcomputer of the VVT controller 250 determines that the engine 10 has been pressed against the stopper during the process of stopping the engine 10, and stops the supply of current to the electric motor 124 in order to reduce unnecessary power consumption, for example.

[0073] In step 45, the microcomputer of VVT controller 250 determines whether the current command value calculated in step 11 is greater than the current limit value. If the microcomputer of VVT controller 250 determines that the current command value is greater than the current limit value (Yes), it proceeds to step 46. On the other hand, if the microcomputer of VVT controller 250 determines that the current command value is not greater than the current limit value, in other words, that the current command value is equal to or less than the current limit value (No), it proceeds to step 47.

[0074] In step 46, the microcomputer of the VVT controller 250 sets the current command value to the current limit value. In short, the microcomputer of the VVT controller 250 limits the current command value to the current limit value.

[0075] In step 47, the microcomputer of the VVT controller 250 supplies a current corresponding to the current command value to the electric motor 124, and performs feedback control of the electric motor 124 by, for example, PID control or PI control. As a result, the electric motor 124 of the VVT mechanism 100 is subjected to speed feedback control.

[0076] In step 48, the microcomputer of VVT controller 250 determines whether the pressure against the stopper has been released, specifically, whether the pressure against the stopper was applied in the previous control cycle and whether the pressure against the stopper is not applied in the current control cycle. If the microcomputer of VVT controller 250 determines that the pressure against the stopper has been released (Yes), it proceeds to step 49. On the other hand, if the microcomputer of VVT controller 250 determines that the pressure against the stopper has not been released (No), it ends the VVT control processing for the current control cycle.

[0077] In step 49, since the pressure against the stopper has been released, the microcomputer of VVT controller 250 clears the integral term in the feedback control. Clearing the integral term in the feedback control makes it possible to suppress a decrease in controllability after the stopper pressure is released. Thereafter, the microcomputer of VVT controller 250 ends the VVT control processing for the current control cycle.

[0078] According to this VVT control process, if it is determined that the electric motor 124 is not being pressed against the stopper, and the absolute value of the deviation between the target speed and the actual speed of the electric motor 124 remains equal to or greater than a predetermined lower limit and equal to or less than a predetermined upper limit for a predetermined period of time, it is determined that the electric motor 124 is being pressed against the stopper. If it is determined that the electric motor 124 is being pressed against the stopper, the actual current value of the current being supplied to the electric motor 124 at that time is saved, and a determination flag indicating the result of the determination as to whether the electric motor 124 is being pressed against the stopper is set to "TRUE." On the other hand, if it is determined that the electric motor 124 is being pressed against the stopper, and the sign of the deviation between the target speed and the actual speed of the electric motor 124 is inverted between the previous control cycle and the current control cycle, the determination flag is cleared to "FALSE." Therefore, it is possible to determine whether the electric motor 124 has been pressed against the stopper or whether the electric motor 124 has been released from pressing against the stopper using the deviation between the target speed and the actual speed of the electric motor 124.

[0079] When it is determined that the electric motor 124 is being pressed against the stopper, if the speed deviation of the electric motor 124 is equal to or greater than 0, it is determined that the electric motor is being pressed against the stopper on the advance angle side, whereas if the speed deviation of the electric motor 124 is less than 0, i.e., is a negative value, it is determined that the electric motor is being pressed against the stopper on the retard angle side. In short, by determining the rotation direction of the electric motor 124 according to the sign of the speed deviation of the electric motor 124, it can be determined whether the electric motor is being pressed against the stopper on the advance angle side or the stopper on the retard angle side.

[0080] When it is determined that the stopper is being pressed against the advance angle side, if the stopper was not pressed against in the previous control cycle but is being pressed against in the current control cycle, it is determined whether the learned value on the advance angle side is equal to or less than the actual current value at the time of determining that the stopper is being pressed against. If the learned value on the advance angle side is equal to or less than the actual current value, it is determined that the learned value on the advance angle side is inappropriate, and the current limit value is set to the actual current value, and the learned value on the advance angle side is also set to the actual current value. On the other hand, if the learned value on the advance angle side is greater than the actual current value at the time of determining that the stopper is being pressed against, it is determined that the learned value on the advance angle side is appropriate, and the learned value on the advance angle side is adopted as the current limit value. Therefore, as a countermeasure for when the stopper is not being pressed against the current limit value, a learned value for limiting the current on the advance angle side can be learned.

[0081] Thereafter, if the actual rotation speed Nm of the electric motor 124 is 0, that is, if the electric motor 124 is being pressed against a stopper while the engine 10 is being stopped, the current limit value is increased by a predetermined value so that the electric motor 124 of the VVT mechanism 100 can rotate against the cam torque of the intake camshaft 36. Then, when the current limit value reaches a predetermined upper current limit value, it is determined that the electric motor 124 is being pressed against the stopper, and power to the electric motor 124 is turned off. Therefore, if the electric motor 124 is being pressed against the stopper while the engine 10 is being stopped, power to the electric motor 124 is turned off, thereby reducing unnecessary power consumption.

[0082] To press the electric motor 124 against the advance angle side stopper, it is necessary to rotate the electric motor 124 faster than the rotational speed of the intake camshaft 36. For this reason, by limiting the value of the current supplied to the electric motor 124, the rotational speed of the electric motor 124 may fall below the rotational speed of the intake camshaft 36, as shown in Fig. 10, and it may become impossible to press the electric motor 124 against the advance angle side stopper. Therefore, if it is not possible to continue pressing the electric motor 124 against the advance angle side stopper, the current limit value is increased by a predetermined value as shown in Fig. 11, so that it becomes possible to press the electric motor 124 against the advance angle side stopper.

[0083] On the other hand, if it is determined that the electric motor 124 is being pressed against the retard side stopper, and the actual rotation speed Nm of the electric motor 124 is equal to or lower than a predetermined rotation speed, i.e., the rotation speed of the intake camshaft 36 is equal to or lower than a predetermined value, it is determined that the electric motor 124 can be pressed against the retard side stopper by the cam torque of the intake camshaft 36. If it is determined that the electric motor 124 can be pressed against the retard side stopper by the cam torque, the electric motor 124 is de-energized to reduce unnecessary power consumption.

[0084] Furthermore, if the stopper was not pressed against the previous control cycle but is pressed against the stopper in the current control cycle, a determination is made as to whether the retard angle side learned value is equal to or less than the actual current value at the time of determining whether the stopper is being pressed against the stopper. If the retard angle side learned value is equal to or less than the actual current, the retard angle side learned value is determined to be inappropriate, and the current limit value is set to the actual current value, and the retard angle side learned value is also set to the actual current value. On the other hand, if the retard angle side learned value is greater than the actual current value at the time of determining whether the stopper is being pressed against the stopper, the retard angle side learned value is determined to be appropriate, and the retard angle side learned value is adopted as the current limit value. Therefore, a learned value for limiting the retard angle side current can be learned as a countermeasure for cases where the stopper is not pressed against the current limit value.

[0085] Thereafter, if the actual rotation speed Nm of the electric motor 124 is 0, that is, if the electric motor 124 is being pressed against a stopper while the engine 10 is being stopped, the current limit value is increased by a predetermined value so that the electric motor 124 of the VVT mechanism 100 can rotate against the cam torque of the intake camshaft 36. Then, when the current limit value reaches a predetermined upper current limit value, it is determined that the electric motor 124 is being pressed against the stopper, and power to the electric motor 124 is turned off. Therefore, if the electric motor 124 is being pressed against the stopper while the engine 10 is being stopped, power to the electric motor 124 is turned off, thereby reducing unnecessary power consumption.

[0086] In this way, when the advance angle side process or the retard angle side process is executed, or when it is determined that the stopper is not being pressed in the current control cycle, if the current command value is greater than the current limit value, the current command value is limited to the current limit value. Then, the electric motor 124 is feedback-controlled in accordance with the current command value. Therefore, as shown in FIG. 12, when the stopper is being pressed, the current value of the current supplied to the electric motor 124 is limited, and it is possible to prevent an excessive current from flowing through the electric motor 124.

[0087] Furthermore, when the pressing against the stopper is released, the integral term of the feedback control of the electric motor 124 is cleared, so that it is possible to suppress a decrease in controllability after the pressing against the stopper is released.

[0088] Furthermore, a person skilled in the art will easily understand that new embodiments can be created by omitting parts of the technical ideas of the above embodiments, combining parts as appropriate, or replacing parts with well-known technology.

[0089] As one example, engine 10 mounted on a vehicle is not limited to a gasoline engine, but may also be a diesel engine. Also, the current limit value for limiting the current supplied to electric motor 124 of VVT mechanism 100 may be a fixed value set in consideration of the characteristics of electric motor 124, for example. Furthermore, it goes without saying that this embodiment is not limited to VVT mechanism 100, but can also be applied to well-known controlled devices that are equipped with a stopper that limits the rotation angle of a rotor that is rotationally driven by a motor. [Explanation of symbols]

[0090] 36... Intake camshaft 36A... Stopper groove 46... Motor rotation speed sensor 100... VVT mechanism 102... Timing sprocket (rotating body) 102A... Stopper protrusion 124... Electric motor 250... VVT controller (motor control device)

Claims

1. A control device for a motor that rotates a rotor provided with a stopper that restricts the rotation angle by speed feedback control, when the absolute value of the deviation between the target rotation speed of the motor and the actual rotation speed of the motor continues to be equal to or greater than a predetermined lower limit value and equal to or less than a predetermined upper limit value for a predetermined time, it is determined that the rotation angle of the rotor is restricted by the stopper, and the current supplied to the motor is restricted. Motor control device.

2. The current supplied to the motor is limited to a predetermined current limit value. The motor control device according to claim 1 .

3. when the absolute value of the deviation between the target rotation speed of the motor and the actual rotation speed of the motor continues to be equal to or greater than a predetermined lower limit value and equal to or less than a predetermined upper limit value for a predetermined period of time, a learned value of the current limit value is learned in accordance with the actual current value of the current supplied to the motor. The motor control device according to claim 2 .

4. determining a rotation direction of the motor according to a sign of a deviation between a target rotation speed of the motor and an actual rotation speed of the motor, and learning the learned values corresponding to the rotation directions of the motor; The motor control device according to claim 3 .

5. When the learned value is equal to or less than the actual current value, the learned value is adopted as the current limit value. The motor control device according to claim 3 .

6. When the current limit value reaches a predetermined current upper limit value, power supply to the motor is stopped. The motor control device according to claim 5 .

7. When the rotation of the motor is stopped by limiting the current supplied to the motor, the current limit value is gradually increased. The motor control device according to claim 2 .

8. in a state in which the current supplied to the motor is limited, a determination is made as to whether or not the rotation angle of the rotating body is restricted by the stopper in accordance with the deviation between the target rotation speed of the motor and the actual rotation speed of the motor when the absolute value of the deviation between the target rotation speed of the motor and the actual rotation speed of the motor continues to be in a state in which the deviation is equal to or greater than a predetermined lower limit value and is equal to or less than a predetermined upper limit value for a predetermined period of time, and the deviation between the current target rotation speed of the motor and the actual rotation speed of the motor; and if it is determined that the rotation angle of the rotating body is not restricted by the stopper, the current limit value is gradually increased. The motor control device according to claim 2 .

9. A control device for a motor that rotates a rotating body provided with a stopper that restricts the rotation angle by speed feedback control, when the absolute value of the deviation between the target rotation speed of the motor and the actual rotation speed of the motor continues to be equal to or greater than a predetermined lower limit value and equal to or less than a predetermined upper limit value for a predetermined time, it is determined that the rotation angle of the rotor is restricted by the stopper, and the current supplied to the motor is restricted. How to control a motor.

10. a control device for the motor that limits the current supplied to the motor to a predetermined current limit value; The motor control method according to claim 9.

11. the motor control device learns a learned value of the current limit value in accordance with an actual current value of the current supplied to the motor when a state in which an absolute value of a deviation between a target rotation speed of the motor and an actual rotation speed of the motor remains equal to or greater than a predetermined lower limit value and equal to or less than a predetermined upper limit value for a predetermined period of time; The motor control method according to claim 10.

12. the motor control device determines a rotation direction of the motor according to a sign of a deviation between a target rotation speed of the motor and an actual rotation speed of the motor, and learns the learned values corresponding to the rotation directions of the motor. The motor control method according to claim 11.

13. the motor control device adopts the learned value as the current limit value when the learned value is equal to or less than the actual current value; The motor control method according to claim 11.

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