JP2005220760A - Variable valve control device and control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase responsiveness while preventing the over-current of a drive motor in a variable valve system control device variably controlling the operating state of the valve system of an internal combustion engine. <P>SOLUTION: The averaged values of the current values and voltage values of the drive motor of a variable valve lift mechanism in a stable state and in a specified period are calculated and a motor resistance value is calculated based on these averaged current value and the averaged voltage value (S101 to S106). When the resistance value is less than a specified value, a motor operating amount is limited to prevent over-current from flowing. When the resistance value is equal to or more than the specified value, the operating amount is not limited and the operating amount is outputted (S107 to S110, S113). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a variable valve control device that drives an operation state such as valve timing and lift amount of a valve (intake / exhaust valve) of an internal combustion engine by an electric actuator, and a control device that drives other control objects by the electric actuator.

Conventionally, there is a technology for controlling the motor drive of an electric actuator by driving a throttle valve with a motor, and a control gain is set so as to compensate for a change in operating characteristics that changes between a low opening and a high opening of the throttle valve. It has corrected (refer patent document 1).
JP 2000-130189 A

However, the above configuration does not compensate for the motor operating characteristics that change in accordance with changes in the temperature of the motor, so that there is a problem that responsiveness varies depending on the heat generation state of the motor.
Further, when the motor temperature is relatively high and the resistance value is large, the current flowing through the motor is reduced with respect to the operation amount, so the motor output is also reduced. For this reason, it is necessary to set the control gain so that the required control characteristics can be obtained. However, if the motor temperature is low and the resistance value is small, a high current will flow. There is a problem that an expensive driving circuit that can be used is required and the cost is increased.

  The present invention has been made by paying attention to such a conventional problem. In a variable valve control device and other control devices that drive an object to be controlled by an electric actuator, the present invention responds to a change in temperature of a motor that is a drive source. The purpose is to be able to compensate for a change in resistance value.

For this reason, the invention according to claim 1 is a variable valve control device that changes an operating state of a valve of an internal combustion engine with an electric actuator, and detects a resistance value of a motor that is a drive source of the electric actuator, The operation amount of the motor is limited and the restriction is released according to the resistance value.
In this way, the amount of operation of the motor is limited and released according to the resistance value of the motor, so variation in responsiveness due to a change in the resistance value of the motor can be prevented, and an expensive drive circuit corresponding to a high current is also provided. It becomes unnecessary.

The invention according to claim 2 limits the operation amount of the motor when the resistance value of the motor is smaller than a predetermined value, and restricts the operation amount of the motor when the resistance value is larger than the predetermined value. It was set as the structure which cancels | releases.
In this way, when the motor resistance value is small and the actuator drive amount relative to the motor operation amount is large, the motor operation amount is limited, and the resistance value increases and the actuator drive amount becomes relatively small. In this case, since the restriction on the operation amount can be released and a large operation amount can be given, a stable drive amount can be obtained even when the resistance value of the motor changes, and response variations can be prevented. Further, when the resistance value is small, the operation amount is limited, and the maximum current value is suppressed, so that an inexpensive drive circuit can be used and the cost can be reduced.

According to a third aspect of the present invention, the voltage applied to the motor and the amount of current flowing through the motor are detected, and the resistance value of the motor is detected based on the average value of these detected values.
In this way, since the resistance value is calculated with the average value, a calculation error can be prevented and the resistance value can be calculated correctly.
According to a fourth aspect of the present invention, there is provided a control device that drives an object to be controlled by an electric actuator, wherein a resistance value of a motor that is a driving source of the electric actuator is detected, and an operation amount of the motor is determined according to the resistance value. Is configured to restrict and release the restriction.

  In this way, the same effect can be obtained by applying the present invention to a control device other than the variable valve control device, for example, a throttle control device that drives a throttle valve with an electric actuator.

FIG. 1 is a configuration diagram of an internal combustion engine for a vehicle in the embodiment.
In FIG. 1, an electronic control throttle 104 that opens and closes a throttle valve 103 b by a throttle motor 103 a is interposed in an intake pipe 102 of the internal combustion engine 101, and the combustion chamber is connected via the electronic control throttle 104 and the intake valve 105. Air is inhaled into 106.

The combustion exhaust is discharged from the combustion chamber 106 through the exhaust valve 107, purified by the front catalyst 108 and the rear catalyst 109, and then released into the atmosphere.
The exhaust valve 107 is driven to open and close by a cam 111 pivotally supported by the exhaust camshaft 110 while maintaining a constant lift amount and operating angle (crank angle from opening to closing), while the intake valve 105 is variable. The lift amount and the operating angle are continuously changed by the valve lift mechanism 112. It should be noted that the lift amount and the operating angle can be changed simultaneously so that if one characteristic is determined, the other characteristic is also determined.

  Similarly, on the intake side, the variable is constituted by a mechanism that continuously and variably controls the rotational phase difference between the crankshaft and the intake camshaft to advance and retard the valve timing (valve opening / closing timing) of the intake valve 105. An intake side cam angle sensor 202 for detecting the rotational position of the valve timing mechanism 201 and the intake side camshaft is provided at both ends of the intake side camshaft. As described above, the variable valve lift mechanism 112 and the variable valve timing mechanism 201 are provided as a plurality of variable valve mechanisms that change the lift amount (operation angle) and the valve timing, which are different operation characteristics of the intake valve 105, respectively. .

The variable valve timing mechanism 201 is a mechanism that changes the valve timing of the intake valve 105 by changing the rotation phase of the intake camshaft 134 with respect to the crankshaft 120. In this embodiment, a spiral radial as will be described later. Adopts a link type variable valve timing mechanism.
In this embodiment, the variable valve timing mechanism 201 is provided only on the intake valve 105 side. However, a variable valve timing mechanism is provided on the exhaust valve 107 side instead of the intake valve 105 side or together with the intake valve 105 side. The structure provided may be sufficient.

In addition, an electromagnetic fuel injection valve 131 is provided in the intake port 130 of each cylinder. When the fuel injection valve 131 is driven to open by an injection pulse signal from an engine control unit (ECU) 114, a predetermined value is set. The fuel adjusted to the pressure is injected toward the intake valve 105.
Detection signals from various sensors are input to the ECU 114 incorporating the microcomputer, and the electronic control throttle 104, the variable valve timing mechanism 201, and the fuel injection valve 131 are controlled by arithmetic processing based on the detection signals.

  Examples of the various sensors include an accelerator opening sensor APS116 for detecting the accelerator opening, an air flow meter 115 for detecting the intake air amount Q of the engine 101, a reference crank angle signal REF (reference rotation for each crank angle of 180 ° from the crankshaft 120). Position signal) and a unit angle signal POS for each unit crank angle, a crank angle sensor 117 for detecting the opening TVO of the throttle valve 103b, a water temperature sensor 119 for detecting the coolant temperature of the engine 101, and an intake side cam A cam angle sensor 202 is provided for extracting a cam signal CAM (reference rotation position signal) for each cam angle 90 ° (crank angle 180 °) from the shaft 134.

The ECU 114 calculates the engine rotational speed Ne based on the cycle of the reference crank angle signal REF or the number of unit angle signals POS generated per unit time.
2 to 4 show the structure of the variable valve lift mechanism 112 in detail.
The variable valve lift mechanism shown in FIGS. 2 to 4 includes a pair of intake valves 105, 105, a hollow camshaft 13 (drive shaft) rotatably supported by the camshaft receiver 14 of the cylinder head 11, Two eccentric cams 15 and 15 (drive cams), which are rotational cams supported on the camshaft 13, and a control shaft 16 rotatably supported by the same camshaft receiver 14 above the camshaft 13. A pair of rocker arms 18, 18 supported on the control shaft 16 via a control cam 17 so as to be swingable, and a pair of rocker arms 19, 19 disposed at upper ends of the intake valves 105, 105 via valve lifters 19, 19. Independent rocking cams 20 and 20 are provided.

The eccentric cams 15 and 15 and the rocker arms 18 and 18 are linked by link arms 25 and 25, and the rocker arms 18 and 18 and the swing cams 20 and 20 are linked by link members 26 and 26.
The rocker arms 18, 18, the link arms 25, 25, and the link members 26, 26 constitute a transmission mechanism.

As shown in FIG. 5, the eccentric cam 15 has a substantially ring shape and includes a small-diameter cam main body 15a and a flange portion 15b integrally provided on the outer end surface of the cam main body 15a. A camshaft insertion hole 15 c is formed through the shaft, and the axis X of the cam body 15 a is eccentric from the axis Y of the camshaft 13 by a predetermined amount.
The pair of eccentric cams 15 are press-fitted and fixed to the camshaft 13 on both outer sides that do not interfere with the valve lifter 19 through camshaft insertion holes 15c, and the outer peripheral surface 15d of the cam body 15a is the same. The cam profile is formed.

As shown in FIG. 4, the rocker arm 18 is bent in a substantially crank shape, and a central base portion 18 a is supported by the control cam 17 in a self-rotating manner.
A pin hole 18d into which a pin 21 connected to the tip end of the link arm 25 is press-fitted is formed at one end 18b protruding from the outer end of the base 18a, while the inner end of the base 18a is formed. A pin hole 18e into which a pin 28 connected to one end portion 26a (described later) of each link member 26 is press-fitted is formed in the other end portion 18c projecting from the portion.

The control cam 17 has a cylindrical shape, is fixed to the outer periphery of the control shaft 16, and the position of the axis P1 is eccentric from the axis P2 of the control shaft 16 by α as shown in FIG.
As shown in FIGS. 2, 6, and 7, the rocking cam 20 has a substantially horizontal U shape, and a cam shaft 13 is fitted into a substantially annular base end portion 22 so as to be rotatably supported. A support hole 22a is formed through, and a pin hole 23a is formed through the end 23 located on the other end 18c side of the rocker arm 18.

Further, a base circle surface 24a on the base end portion 22 side and a cam surface 24b extending in an arc shape from the base circle surface 24a toward the end edge side of the end portion 23 are formed on the lower surface of the swing cam 20. The circular surface 24 a and the cam surface 24 b come into contact with predetermined positions on the upper surfaces of the valve lifters 19 in accordance with the swing position of the swing cam 20.
That is, when viewed from the valve lift characteristics shown in FIG. 8, as shown in FIG. 2, the predetermined angle range θ1 of the base circle surface 24a becomes the base circle section, and the predetermined angle range θ2 from the base circle section θ1 of the cam surface 24b changes. This is a so-called ramp section, and further, a predetermined angle range θ3 from the ramp section θ2 of the cam surface 24b is set to be a lift section.

The link arm 25 includes an annular base portion 25a and a projecting end 25b projecting at a predetermined position on the outer peripheral surface of the base portion 25a. At the center position of the base portion 25a, the cam body of the eccentric cam 15 is provided. A fitting hole 25c is formed in the outer peripheral surface of 15a so as to be freely rotatable, and a pin hole 25d through which the pin 21 is rotatably inserted is formed in the protruding end 25b.
Further, the link member 26 is formed in a straight line having a predetermined length, and circular pin ends 26a and 26b have pin holes 18d in the other end 18c of the rocker arm 18 and the end 23 of the swing cam 20, respectively. , 23a, and pin insertion holes 26c and 26d through which end portions of the pins 28 and 29 are rotatably inserted are formed.

In addition, snap rings 30, 31, and 32 that restrict the axial movement of the link arm 25 and the link member 26 are provided at one end of each pin 21, 28, and 29.
In the above configuration, the lift amount varies as shown in FIGS. 6 and 7 depending on the positional relationship between the axis P2 of the control shaft 16 and the axis P1 of the control cam 17, and the control shaft 16 is driven to rotate. As a result, the position of the axis P2 of the control shaft 16 with respect to the axis P1 of the control cam 17 is changed.

  The control shaft 16 is driven to rotate within a predetermined rotation angle range between a minimum angle position and a maximum angle position defined by a stopper by a DC servo motor (actuator) 121 with the configuration shown in FIG. By changing the operating angle of the control shaft 16 by the actuator 121, the lift amount and the operating angle of the intake valve 105 change continuously (see FIG. 9).

In FIG. 10, the DC servo motor 121 is arranged so that its rotation shaft is parallel to the control shaft 16, and a bevel gear 122 is pivotally supported at the tip of the rotation shaft.
On the other hand, a pair of stays 123a and 123b are fixed to the tip of the control shaft 16, and a nut 124 is swingably supported around an axis parallel to the control shaft 16 connecting the tips of the pair of stays 123a and 123b. The

A bevel gear 126 meshed with the bevel gear 122 is pivotally supported at the tip of the screw rod 125 meshed with the nut 124, and the screw rod 125 is rotated by the rotation of the DC servo motor 121. The position of the nut 124 that meshes with the 125 is displaced in the axial direction of the screw rod 125 so that the control shaft 16 is rotated.
Here, the direction in which the position of the nut 124 is brought closer to the bevel gear 126 is a direction in which the lift amount is reduced, and conversely, the direction in which the position of the nut 124 is moved away from the bevel gear 126 is a direction in which the lift amount is increased. .

  As shown in FIG. 10, a Hall IC type rotation angle sensor 127 that detects the rotation angle of the control shaft 16 is provided at the tip of the control shaft 16, and the actual angle detected by the rotation angle sensor 127 is detected. The control unit 114 feedback-controls the DC servo motor 121 so that the rotation angle matches the target rotation angle. Here, since the lift amount and the operating angle can be changed simultaneously by the rotation angle control of the control shaft 16, the rotation angle sensor 127 is a sensor that detects the lift amount at the same time as detecting the operating angle of the intake valve 105.

  Next, the configuration of the variable valve timing mechanism (VTC) 201 will be described with reference to FIGS. As shown in FIG. 11, the camshaft 134 on the intake side and the front end portion of the camshaft 134 are assembled so that they can be rotated relative to each other as necessary, and are attached to the crankshaft 120 via a chain (not shown). A drive link 303 (drive rotator) having a timing sprocket 302 linked to the outer periphery, and the drive ring 3 and the camshaft 134 are disposed on the front side (left side in FIG. 11). An assembly angle operation mechanism 304 for operating the assembly angle, an operation force applying means 305 that is disposed further forward of the assembly angle operation mechanism 304 and drives the mechanism 304, and a cylinder head and a head cover (not shown) of the internal combustion engine. An assembly angle operating mechanism 304 and a VTC cover (not shown) covering the front surface and peripheral area of the operating force applying means 305. .

  The drive ring 303 is formed in a short shaft cylindrical shape having a step-like insertion hole 306, and the insertion hole 306 portion rotates to a driven shaft member 307 (driven rotating body) coupled to the front end portion of the camshaft 134. It is assembled as possible. As shown in FIG. 12, three radial grooves 308 (radial guides) having parallel side walls facing each other are provided on the front surface of the drive ring 303 (the surface opposite to the camshaft 134). It is formed so as to be along the substantially radial direction.

  Further, as shown in FIG. 11, the driven shaft member 307 has a diameter-enlarged portion formed on the base-side outer periphery that abuts against the front end portion of the camshaft 134, and an outer peripheral surface on the front side of the enlarged-diameter portion The three levers 309 projecting radially are integrally formed, and are coupled to the camshaft 134 by bolts 310 penetrating the shaft core portion. The base end of each link 311 is pivotally connected to each lever 309 by a pin 312, and a columnar protrusion 313 slidably engaged with each radial groove 308 is integrally formed at the tip of each link 311. Is formed.

  Since each link 311 is connected to the driven shaft member 307 via the pin 312 in a state where the protruding portion 313 is engaged with the corresponding radial groove 308, the distal end side of the link 311 receives an external force and receives the radial groove. When displaced along 308, the drive ring 303 and the driven shaft member 307 are relatively rotated by the action of the link 311 by a direction and an angle corresponding to the displacement of the protrusion 313.

  In addition, a housing hole 314 that opens to the front side in the axial direction is formed at the tip of each link 311, and the housing hole 314 has a spherical protrusion 316 a that engages with a spiral groove 315 (spiral guide) described later. An engagement pin 316 (rolling member) and a coil spring 317 that biases the engagement pin 316 forward (spiral groove 315 side) are accommodated. In this embodiment, a movable guide portion that is displaceable in the radial direction is constituted by the protruding portion 313 at the tip of the link 311, the engagement pin 316, the coil spring 317, and the like.

  On the other hand, an intermediate rotating body 318 having a disk-like flange wall 318 a is rotatably supported via a bearing 331 in front of the protruding position of the lever 309 of the driven shaft member 307. The aforementioned spiral groove 315 having a semicircular cross section is formed on the rear surface side of the flange wall 318a of the intermediate rotating body 318, and the engagement pin 316 at the tip of each link 311 can roll freely in the spiral groove 315. The guide is engaged. The spiral of the spiral groove 315 is formed so as to gradually reduce the diameter along the rotation direction of the drive ring 303. Therefore, in the state where the engagement pin 316 at the tip of each link 311 is engaged with the spiral groove 315, when the intermediate rotator 318 rotates relative to the drive ring 303 in the delay direction, the tip of the link 311 becomes the radial groove 308. When the intermediate rotating body 318 is relatively displaced in the advancing direction, it is guided radially by the spiral shape of the spiral groove 315 and conversely moves in the radial direction.

  The assembly angle operation mechanism 304 of this embodiment is constituted by the radial groove 308, the link 311, the protrusion 313, the engagement pin 316, the lever 309, the intermediate rotating body 318, the spiral groove 315, etc. of the drive ring 303 described above. Has been. When the relative turning operation force with respect to the camshaft 134 is input from the operation force applying means 305 to the intermediate rotating body 318, the assembly angle operation mechanism 304 receives the operation force from the spiral groove 315 and the engagement pin 316. The distal end of the link 311 is displaced in the radial direction through the engaging portion, and at this time, relative rotational force is transmitted to the drive link 303 and the driven shaft member 307 by the action of the link 311 and the lever 309.

  On the other hand, the operating force applying means 305 includes a spring 319 that urges the intermediate rotator 318 in the rotation direction of the drive ring 303 and a braking mechanism that urges the intermediate rotator 318 in the direction opposite to the rotation direction of the drive ring 303. The intermediate rotating body 318 relative to the drive ring 303 by appropriately controlling the braking force of the hysteresis brake 320 according to the operating state of the internal combustion engine, or Is configured to maintain the rotational position of both.

The spring spring 319 has an outer peripheral end coupled to a cylindrical member 321 integrally attached to the drive ring 303, while an inner peripheral end is coupled to a cylindrical base of the intermediate rotating body 318, and the whole is intermediate. The rotating body 318 is disposed in the space on the front side of the flange wall 318a.
On the other hand, the hysteresis brake 320 is in a state in which the rotation is restricted by a bottomed cylindrical hysteresis ring 323 attached to the front end portion of the intermediate rotating body 318 via a retainer plate 322 and a VTC cover (not shown) which is a non-rotating member. And a coil yoke 325 which is a magnetic induction member for guiding the magnetism of the electromagnetic coil 324. The electromagnetic coil 324 is energized by the ECU 114 according to the operating state of the engine. To be controlled.

As shown in FIG. 15, the hysteresis ring 323 is formed of a hysteresis material (semi-hard material) having a characteristic (magnetic hysteresis characteristic) in which magnetic flux force changes with a phase lag with respect to a change in an external magnetic field, and the outer peripheral side. The cylindrical wall 323a is subjected to a braking action by the coil yoke 325.
The entire coil yoke 325 is formed in a substantially cylindrical shape so as to surround the electromagnetic coil 324, and an inner peripheral surface thereof is rotatably supported by the tip end portion of the driven shaft member 307 via a bearing 328. A pair of circumferential facing surfaces 326 and 327 are formed on the rear surface side (intermediate rotating body 318 side) of the coil yoke 325 so that the magnetic input / output portions face each other with a cylindrical gap.

Further, as shown in FIG. 13, a plurality of concavities and convexities are continuously formed along the circumferential direction on both opposing surfaces 326 and 327 of the coil yoke 325, and the convex portions 326a and 327a of these concavities and convexities are formed as magnetic poles (Magnetic field generator).
And the convex part 326a of one opposing surface 326 and the convex part 327a of the other opposing surface 327 are alternately arrange | positioned in the circumferential direction, and the convex parts 326a and 327a which the opposing surfaces 326 and 327 mutually adjoin are all the circumferential direction. It is shifted to. Accordingly, a magnetic field having a direction inclined in the circumferential direction as shown in FIG. 16 is generated between the convex portions 326a and 327a adjacent to each other on the opposing surfaces 326 and 327 by the excitation of the electromagnetic coil 24. A cylindrical wall 323a of the hysteresis ring 323 is interposed in a non-contact state in the gap between the opposing surfaces 326 and 327.

Here, the operating principle of the hysteresis brake 320 will be described with reference to FIG. 17A shows a state where a magnetic field is first applied to the hysteresis ring 323 (hysteresis material), and FIG. 17B shows a state where the hysteresis ring 323 is displaced (rotated) from the state of FIG. Indicates.
17A, the direction of the magnetic field between the opposing surfaces 326 and 327 of the coil yoke 325 (the direction of the magnetic field from the convex portion 327a of the opposing surface 27 toward the convex portion 327a of the other opposing surface 326) is met. Thus, a magnetic flux flows in the hysteresis ring 323.

  When the hysteresis ring 323 is moved in response to the external force F as shown in FIG. 17B from this state, the hysteresis ring 323 is displaced in the external magnetic field. At this time, the magnetic flux inside the hysteresis ring 323 is phase-shifted. With a delay, the direction of the magnetic flux inside the hysteresis ring 323 is shifted (tilted) with respect to the direction of the magnetic field between the opposing surfaces 326 and 327. Therefore, the flow of magnetic flux (magnetic lines) entering the hysteresis ring 323 from the convex portion 327a of the opposing surface 327 and the flow of magnetic flux (magnetic lines) from the hysteresis ring 323 toward the convex portion 326a of the other opposing surface 326 are distorted. An attractive force that corrects the distortion of the magnetic flux acts between the opposing surfaces 326 and 327 and the hysteresis ring 323, and the attractive force acts as a drag force F ′ that brakes the hysteresis ring 323.

  When the hysteresis ring 323 is displaced in the magnetic field between the opposing surfaces 326 and 327 as described above, the hysteresis brake 320 generates a braking force due to a deviation between the direction of the magnetic flux inside the hysteresis ring 323 and the direction of the magnetic field. However, the braking force depends on the strength of the magnetic field, that is, the magnitude of the excitation current of the electromagnetic coil 324, regardless of the rotational speed of the hysteresis ring 323 (relative speed between the opposed surfaces 326 and 327 and the hysteresis ring 323). It becomes a constant value approximately proportional to.

  FIG. 18 shows test results obtained by examining the relationship between the rotational speed and the braking torque in the hysteresis brake 320 of this embodiment by changing the excitation current to a to d (a <b <c <d). As is apparent from this test result, the hysteresis brake 320 is not affected by the rotational speed unlike the brake using eddy current, and can always obtain a braking force according to the excitation current value.

  The variable valve timing mechanism (VTC) 201 according to the present embodiment has the above-described configuration. When the excitation of the electromagnetic coil 324 of the hysteresis brake 320 is turned off, the intermediate rotating body 318 is moved by the urging force of the mainspring spring 319. The rotation is maximum in the engine rotation direction with respect to the drive ring 303, and the engagement pin 316 is restricted at a position where it abuts against the outer peripheral end surface 315 a of the spiral groove 315. The retard position is reached (see FIG. 12).

  When the excitation of the electromagnetic coil 324 is turned on from this state, a braking force against the force of the mainspring spring 319 is applied to the intermediate rotating body 318, and the intermediate rotating body 318 rotates in the reverse direction with respect to the drive ring 303, As a result, the engaging pin 316 at the tip of the link 311 is guided to the spiral groove 315 and the tip of the link 311 is displaced along the radial groove 308, and the drive ring 303 and the driven shaft member 307 are assembled by the action of the link 11. The angle is changed to the advance side. When the exciting current of the electromagnetic coil 324 is increased to increase the braking force, the engagement pin 316 is finally regulated at a position where it abuts against the inner peripheral side end surface 315b of the spiral groove 315, and this position is determined by the VTC 201. It becomes the most advanced position of the rotational phase that can be changed on the mechanism (see FIG. 14).

If the exciting current of the electromagnetic coil 324 is reduced from this state to reduce the braking force, the intermediate rotating body 318 is rotated back in the forward direction by the biasing force of the mainspring spring 319, and the link 311 is guided by the engagement pin 316 by the spiral groove 315. Oscillates in the opposite direction to the above, and the assembly angle of the drive ring 303 and the driven shaft member 307 is changed to the retard side.
As described above, the rotational phase (of the camshaft 134 with respect to the crankshaft 120) that is varied by the VTC 201 is controlled to an arbitrary phase by controlling the exciting current value of the electromagnetic coil 324 and controlling the braking force of the hysteresis brake 320. The phase can be maintained by changing the balance of the force of the mainspring spring 319 and the braking force of the hysteresis brake 320.

  In such a configuration, as an embodiment of the present invention, the resistance value of the DC servo motor 121 which is a drive source in the variable valve lift mechanism (VEL) 112 which is one of the variable valve mechanisms is calculated, and the motor is calculated according to the resistance value. The operation amount 121 is controlled while being restricted and released. For this reason, a current sensor 203 for detecting a current value supplied to the motor 121 is provided, and a resistance value is calculated from the current value detected by the current sensor 203 and the applied voltage of the motor 121.

FIG. 19 shows a control flow of the motor 121 in the VEL 112.
In step 101, a motor operation amount (applied voltage) is calculated. Specifically, the target valve lift amount (target valve operating angle) of the intake valve is calculated based on the engine operating state (rotational speed, load, water temperature, etc.), and functions as the target valve lift amount and the lift amount sensor. It is calculated by PID control or the like based on the deviation from the actual valve lift detected by the rotation angle sensor 127.

In step 102, the motor current value detected by the current sensor 203 is measured.
In step 103, the absolute value of the change amount between the previous measurement value and the current measurement value of the motor current value is equal to or less than a predetermined value, and the absolute value of the change amount between the previous measurement value and the current measurement value of the previous motor operation amount. Is less than or equal to a certain value, that is, whether or not the condition for holding control at substantially the same position is satisfied.

When it is determined that the holding control condition is satisfied, the process proceeds to step 104 to calculate the average current value and the average operation amount during the holding control condition being satisfied, and the time for which the holding control condition is satisfied. Increment the counter that measures.
In step 105, it is determined based on the measured value of the counter whether the holding control condition is satisfied for a predetermined time.

When it is determined that the holding control condition is satisfied for a certain period of time, the process proceeds to step 106, where the resistance value of the motor is determined based on the average current value and the average operation amount (average voltage value) for the certain period of time. Calculate as in the equation.
Motor resistance value = average voltage value / average current value In step 107, it is determined whether or not the calculated resistance value is smaller than a predetermined value.

  When it is determined in step 107 that the resistance value is smaller than the predetermined value, the process proceeds to step 108 and processing for limiting the motor operation amount is performed. For simplicity, the upper limit operation amount is set as a fixed value, and the operation amount calculated in step 101 is compared with the upper limit operation amount. When the operation amount is less than the upper limit operation amount, the operation amount is set as it is. When it exceeds, the upper limit operation amount is reset as the operation amount. In addition, an upper limit current is set, a value obtained by multiplying the resistance value calculated in step 106 by the upper limit current is calculated as an upper limit operation amount, and thereafter, the operation amount is set so as not to exceed the upper limit operation amount as described above. Therefore, it is possible to perform the restriction with higher accuracy, and the necessary minimum restriction is sufficient.

If it is determined that the resistance value calculated in step 107 is equal to or greater than the predetermined value, the process proceeds to step 109, and the operation amount calculated in step 101 is set as the operation amount as it is without limiting the motor operation amount.
In step 110, the control average current value, the average operation amount, and the counter for measuring the holding control condition establishment time are cleared, and then the process proceeds to step 113 and the motor operation finally set in step 108 or step 109 is performed. The amount is output to the motor 121.

  On the other hand, when it is determined in step 103 that the holding control condition is not satisfied, the routine proceeds to step 111, and after clearing the counter for measuring the holding control condition establishment time, the routine proceeds to step 112. If it is determined at 105 that the holding control condition has not been satisfied for a certain period of time, the process proceeds directly to step 112, the previous motor operation amount restriction processing method (presence / absence of restriction) is continued, and the final operation amount is set. Proceeding to step 113, the motor operation amount is output. That is, if the previous operation amount is limited with respect to the motor operation amount calculated in step 101, this time is also limited, and if the previous operation amount is not limited, the current operation is output without limitation.

In this way, a stable drive amount of the VEL 112 can be obtained even if the resistance value of the motor changes, and response variations can be prevented. Further, when the resistance value is small, the operation amount is limited, and the maximum current value is suppressed, so that an inexpensive drive circuit can be used and the cost can be reduced.
In the above embodiment, the resistance value of the motor is calculated from the current value and the operation amount (voltage). However, the resistance value may be estimated from the heat generation temperature of the motor.

In the above embodiment, the current value and the operation amount (voltage) are averaged. However, the calculated resistance value is averaged, and the operation amount is limited / canceled based on the averaged resistance value. Also good.
The present invention can also be applied to a variable valve timing mechanism (VTC) 201, which is another variable valve mechanism. In this case, the resistance value of the electromagnetic coil (motor) 324 that is a driving source in the VTC 201 is calculated, and the operation amount of the electromagnetic coil 324 is controlled according to the resistance value while restricting and releasing the restriction. For this reason, a current sensor 204 for detecting a current value supplied to the electromagnetic coil 324 is provided, and a resistance value is calculated from the current value detected by the current sensor 204 and the applied voltage of the electromagnetic coil 324.

  The control flow of the electromagnetic coil (motor) 324 is the same as that of the motor 121 in the VEL 112. That is, in FIG. 19, the motor is the electromagnetic coil 324, and the motor current value may be the current value of the electromagnetic coil 324 detected by the current sensor 204 (calculation of the motor operation amount (applied voltage) in step 101). , Based on the deviation between the target valve timing of the intake valve calculated based on the engine operating state (rotational speed, load, water temperature, etc.) and the actual valve timing detected by the cam angle sensor 202, and so on, by PID control or the like. ).

As described above, the same effect can be obtained by applying the present invention to a control device other than the variable valve control device, for example, a throttle control device that drives a throttle valve with an electric actuator.
Further, technical ideas other than the claims that can be grasped from the above embodiment will be described together with the effects thereof.
(A) In the variable valve control apparatus according to any one of claims 1 to 3 or the control apparatus according to claim 4, the resistance value of the motor is estimated and calculated from a heat generation temperature of the motor. It is characterized by doing.
(B) In the variable valve control apparatus or control apparatus according to any one of claims 1 to 4 or (a) above, the calculated resistance value of the motor is averaged, and the averaged resistance value is calculated. It is characterized in that the operation amount of the motor is restricted and the restriction is released.
(C) In the variable valve control apparatus or control apparatus according to any one of claims 1 to 4 or any one of (a) and (b) above, the limit of the motor operation amount is a preset upper limit. It is characterized by not exceeding the operation amount.
Motor (d) In the variable valve control apparatus or control apparatus according to any one of claims 1 to 4 or (b) above, the limit of the motor operation amount is preset to the calculated resistance value. The upper limit operation amount calculated by multiplying the upper limit current value is not exceeded.

The system block diagram of the internal combustion engine provided with the valve operating control apparatus which concerns on this invention. Sectional drawing which shows a variable valve lift mechanism (AA sectional drawing of FIG. 3). The side view of the said variable valve lift mechanism. The top view of the said variable valve lift mechanism. The perspective view which shows the eccentric cam used for the said variable valve lift mechanism. Sectional drawing which shows the effect | action at the time of the low lift of the said variable valve lift mechanism (BB sectional drawing of FIG. 3). Sectional drawing which shows the effect | action at the time of the high lift of the said variable valve lift mechanism (BB sectional drawing of FIG. 3). The valve lift characteristic view corresponding to the base end face and cam surface of the swing cam in the variable valve lift mechanism. The valve timing of the said variable valve lift mechanism and the characteristic figure of a valve lift. The perspective view which shows the rotational drive mechanism of the control shaft in the said variable valve lift mechanism. Sectional drawing which shows a variable valve timing mechanism. Sectional drawing which follows the AA line of FIG. Sectional drawing which follows the BB line of FIG. Sectional drawing similar to FIG. 12 which shows the operating state of the said variable valve timing mechanism. The graph which shows the magnetic flux density-magnetic field characteristic of a hysteresis material. FIG. 14 is a partial enlarged cross-sectional view of FIG. 13. It is the schematic diagram which expand | deployed the components of FIG. 16 linearly, and is a figure which shows the flow of the magnetic flux when the initial state (a) and a hysteresis ring rotate (b). The graph which shows the brake torque-rotation speed characteristic (a) of the said variable valve timing mechanism, and the brake torque-rotation speed characteristic (b) of a prior art. The flowchart of the motor control in embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Internal combustion engine, 105 ... Intake valve, 112 ... Variable valve lift mechanism, 114 ... Engine control unit, 117 ... Crank angle sensor, 120 ... Crank shaft, 121 ... DC servo motor, 134 ... Cam shaft, 201 ... Variable valve timing Mechanism 202 ... Cam angle sensor 203 ... Current sensor 204 ... Current sensor 324 ... Electromagnetic coil

Claims (4)

  A variable valve control apparatus that changes an operating state of a valve of an internal combustion engine by an electric actuator, detects a resistance value of a motor that is a drive source of the electric actuator, and operates an operation amount of the motor according to the resistance value The variable valve control apparatus characterized by restricting and releasing the restriction.   The operation amount of the motor is limited when the resistance value of the motor is smaller than a predetermined value, and the restriction of the operation amount of the motor is released when the resistance value is larger than a predetermined value. 2. The variable valve control apparatus according to 1.   The voltage applied to the motor and the amount of current flowing through the motor are detected, and the resistance value of the motor is detected based on an average value of these detected values. Variable valve controller.   A control device that drives an object to be controlled by an electric actuator, wherein a resistance value of a motor that is a driving source of the electric actuator is detected, and an operation amount of the motor is limited and released according to the resistance value. Control device.

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