JP4811269B2 - Variable valve mechanism controller - Google Patents

Description

  This invention controls a variable valve mechanism that controls the opening / closing timing of an intake valve or an exhaust valve by changing a relative angle (conversion angle) between a camshaft and a camshaft drive sprocket by hydraulic pressure. Relates to the device.

2. Description of the Related Art A control device for a variable valve mechanism that controls the opening / closing timing of an intake valve or an exhaust valve by changing the relative angle (conversion angle) between a camshaft and a camshaft drive sprocket is known. (See Patent Document 1).
JP 2005-233153 A

  However, the present inventors have found that the above-described conventional variable valve mechanism control device cannot obtain a desired conversion angle control accuracy.

  The present invention has been made paying attention to such conventional problems, and provides a variable valve mechanism control device that can increase the control accuracy of the conversion angle and suppress the overshoot of the conversion angle. The purpose is to do.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

The present invention is a control apparatus for a variable valve mechanism that adjusts a conversion angle by moving a solenoid valve (40) to control the amount of hydraulic oil, and inputs a target conversion angle, and the variable valve mechanism (30). A model reference type control unit (B41) that outputs a feedforward control signal for controlling the target conversion angle according to the target conversion angle, and a control target model unit (B43) that calculates a reference conversion angle based on the feedforward control signal; , A feedforward compensator (B4) including a feedback compensator (B6) that outputs a feedback control signal based on the reference conversion angle and an actual conversion angle of the variable valve mechanism, and based on an engine operating state An angular velocity limit value calculator (B2) for calculating a conversion angular velocity limit value of the variable valve mechanism, and a current limit value for calculating a current limit value based on the calculated conversion angular velocity limit value And can (B3), wherein the feedforward compensator (B4), the output from the Model Reference Control unit (B41), the feedforward control until the input to the controlled object model unit (B43) A limit model unit (B42) for limiting the upper and lower limit values of the signal, the limit model unit (B42) being based on the current limit value calculated by the current limit value calculator (B3); And the conversion angle of the variable valve mechanism (30) is controlled by the feedforward control signal limited by the limit model unit (B42) and the feedback control signal output from the feedback compensator (B6). It is characterized by.

  According to the present invention, the feedforward control signal is limited based on the current limit value calculated based on the engine operating state, and the variable valve mechanism is controlled by the feedforward control signal and the feedback control signal output from the feedback compensator. Since the conversion angle is controlled, it is possible to increase the control accuracy of the conversion angle and to prevent the conversion angle from overshooting.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an embodiment of a control device of a variable valve timing control (hereinafter referred to as “VTC”) according to the present invention.

  The VTC control apparatus 1 according to the present embodiment includes a controller 70 and a solenoid valve 40, and controls the VTC conversion angle θ by adjusting the amount of hydraulic oil supplied to the VTC by switching the oil passage by the solenoid valve 40. To do.

  Since the structure of the VTC 30 is known, it will be briefly described here.

  The VTC 30 includes a camshaft 31 and a camshaft drive sprocket 33 that is coaxial with the camshaft 31 and rotates synchronously with the crankshaft of the engine via a belt or chain. By changing the relative angle (conversion angle) with the drive sprocket 33, the opening / closing timing of the intake valve or exhaust valve is controlled to be advanced / retarded.

  The camshaft 31 includes a plurality of vanes 32 that rotate integrally with the camshaft 31.

  The camshaft drive sprocket 33 is provided with a space that allows the vane 32 to rotate. This space is made up of an advance hydraulic chamber 33a and a retard hydraulic chamber 33b by the vane 32.

  The advance hydraulic chamber 33a is connected to a passage switching solenoid valve 40 via an advance oil passage 43a. The retard hydraulic chamber 33b is connected to a solenoid valve 40 for switching the passage via a retard oil passage 43b.

  In addition to the advance oil passage 43a and the retard oil passage 43b, the solenoid valve 40 includes an oil supply passage 42 provided with an oil pump 41 that pumps hydraulic oil of the oil pan 45 in the middle, and an oil pan 45 to the oil pan 45. A drain passage 44 for returning the hydraulic oil is connected.

  The VTC control device 1 changes and holds the hydraulic pressure to the advance hydraulic chamber 33a and the retard hydraulic chamber 33b as appropriate by changing the oil passage by controlling the energization amount to the solenoid valve 40, and changing the conversion angle. Hold. As a result, the VTC 30 controls the advance / retard of the opening / closing timing (valve timing) of the intake valve or the exhaust valve.

  Specifically, when the energization amount to the solenoid valve 40 is increased, the passage is switched to the passage A, and the hydraulic oil in the oil pan 45 is supplied to the advance hydraulic chamber 33a through the advance oil passage 43a. On the other hand, the hydraulic oil in the retarded hydraulic chamber 33 b is discharged to the oil pan 45 through the retarded oil passage 43 b and the drain passage 44. Thereby, the hydraulic pressure in the advance hydraulic chamber 33a becomes relatively high, and the valve timing is advanced.

  Further, when the energization amount to the solenoid valve 40 is decreased, the operation is switched to the passage B, and the hydraulic oil in the oil pan 45 is supplied to the retard hydraulic chamber 33b through the retard oil passage 43b. On the other hand, the hydraulic oil in the advance hydraulic chamber 33 a is discharged to the oil pan 45 through the advance oil passage 43 a and the drain passage 44. As a result, the hydraulic pressure in the retarded hydraulic chamber 33b becomes relatively high, and the valve timing is retarded.

  Control of the energization amount to the solenoid valve 40 is executed by the controller 70. A crank angle sensor 71, a cam angle sensor 72, and a water temperature sensor 73 are connected to the controller 70. The crank angle sensor 71 outputs an angle signal of the crankshaft and outputs a reference crank position signal at the reference rotational position of the crankshaft. The cam angle sensor 72 outputs a reference cam position signal at the reference rotation position of the camshaft 31. The water temperature sensor 73 outputs the engine water temperature.

The controller 70 determines the current conversion angle (hereinafter referred to as “actual conversion angle”) θ of the VTC 30 based on the deviation angle of the reference rotational position between the crankshaft and the camshaft 31 detected by the crank angle sensor 71 and the cam angle sensor 72. Is detected. Then, the energization amount to the solenoid valve 40 is controlled so that the actual conversion angle θ follows the target conversion angle θ _com set based on the operating condition of the engine.

  FIG. 2 is a block diagram showing functions related to the VTC control of the controller. Each block is numbered with a number corresponding to a step number in the flowchart described later with B added at the beginning. Details of specific control contents of each block will be described later along a flowchart.

The controller 70 outputs a current command value I _com for controlling the solenoid valve 40 based on the target conversion angle θ _com . The controller 70 includes an angular velocity limit value calculator B2, a current limit value calculator B3, a feedforward compensator B4, a current saturation determiner B5, and a feedback compensator B6.

Angular velocity limit value calculator B2 receives the rotational speed and the water temperature of the engine, calculates the angular speed upper limit omega _LMT _ _H and the angular velocity lower limit omega _LMT _ _L.

Current limit value calculator B3 inputs the angular velocity limit omega _LMT _ _H and the angular velocity lower limit omega _LMT _ _L, calculates a current limit I _LMT _ _H and a current lower limit value I _LMT _ _L.

The feedforward compensator B4 receives the target conversion angle θ _com and outputs the feed forward current command value I _{com — FF} and the reference response conversion angle θ _sim . Although a specific configuration of the feedforward compensator B4 will be described later, the feedforward compensator B4 has a limit model B42 therein. The limit model B42 uses the limit value calculated by the current limit value calculator B3.

Current saturation determiner B5 receives the current limit I _LMT _ _H and a current lower limit value I _LMT _ _L and the current command value I _com, the current command value I _com determines whether or not saturated state.

The feedback compensator B6 receives the reference response conversion angle θ _sim and the actual conversion angle θ, and outputs a feedback current command value I _{com — FB} so that the actual conversion angle θ matches the reference response conversion angle θ _sim . The feedback compensator B6 inputs the determination result of the current saturation determiner B5, and executes / stops the PID control integration calculation according to the result. The transfer function G _FB (s) of the feedback compensator B6 is expressed by the following equation (1).

The adder B7 inputs the feedforward current command value I _{com — FF} and the feedback current command value I _{com — FB} , adds them together, and outputs a current command value I _com . Then, the solenoid valve 40 is operated by the current command value I _com and the conversion angle θ of the VTC 30 is adjusted.

  FIG. 3 is a diagram illustrating a detailed configuration of the feedforward compensator B4.

The feedforward compensator B4 includes a model matching control unit B41, a limit model B42, and a controlled object model B43. The feedforward compensator B4 receives the target conversion angle θ _com and outputs the feed forward current command value I _{com — FF} and the reference response conversion angle θ _sim .

Model-matching control unit B41, the front limit Enter a value obtained by subtracting the nominal response conversion angle theta _sim from the target conversion angle theta _com and outputs the current command value I _com1. The model matching control unit B41 is a feedback control unit in the feedforward compensator. The transfer function G _MM (s) of the model matching control unit B41 is a reference model transfer characteristic in which a linear characteristic from the target conversion angle θ _com to the reference response conversion angle θ _sim that is the output of the controlled object model is a desired response characteristic. Design to be G _sim (s). The reference model transfer characteristic G _sim (s) is set in the secondary vibration system as shown in the following equation (2).

The transfer function G _MM (s) of the model matching control unit B41 is expressed by the following equation (3).

The restriction model B42 is a model simulating a structure that restricts the current that flows to the controlled object. The conversion angular velocity of the VTC is limited by, for example, the rotational speed of the engine or the water temperature. That is, if the engine speed is low, the hydraulic pressure of the hydraulic oil pumped from the oil pump 41 decreases, so the VTC conversion angular velocity is slow. Further, when the engine water temperature decreases from the optimum water temperature, the viscosity of the hydraulic oil increases and the VTC conversion angular velocity decreases. On the other hand, when the engine water temperature rises from the optimum water temperature, the density of the hydraulic oil becomes coarse, and also in this case, the conversion angular velocity of the VTC becomes slow. Therefore, the conversion angular velocity of the VTC is limited, and a desired response cannot be obtained even if the solenoid valve 40 is controlled with a current equal to or higher than the current for realizing the conversion angular velocity. Therefore, there is an appropriate current range for controlling the solenoid valve 40, and it is necessary to limit the current so as not to exceed the current range. A model that simulates such a current limiting structure is a limiting model B42. Limiting model B42, the output of the feed forward current command value I _com _ _FF to enter a limit before current command value I _com1. As described above, the feedforward current command value I _{com — FF} is obtained by limiting the output of the model matching control unit B41 by the limit model B42.

The controlled object model B43 is a model in which the controlled object is a transfer function G _p (s). The control target model B43 receives the feedforward current command value I _{com — FF} and outputs the reference response conversion angle θ _sim . The transfer function G _p (s) is expressed by the following equation (4), for example.

  Below, the concrete control logic of the controller 70 is demonstrated along a flowchart. FIG. 4 is a flowchart of the main routine of VTC control. The controller 70 repeatedly executes this process in a minute time (for example, 10 milliseconds) cycle.

  In step S1, the controller 70 reads the engine speed and the water temperature.

The controller 70 in step S2 computes the converted angular velocity upper limit omega _LMT _ _H and a conversion angular velocity lower limit omega _LMT _ _L. Specifically, finding a conversion angular velocity upper limit omega _LMT _ _H and a conversion angular velocity lower limit omega _LMT _ _L based on a map of the characteristic shown in FIG. 8 which is stored in advance in ROM. FIG. 8 shows an example of the conversion angular velocity upper limit map, but a similar conversion angular velocity lower limit map is also stored in the ROM. These maps are set in advance through experiments. FIG. 9A shows an example in which FIG. 8 is cut out at a constant engine speed. FIG. 9B shows an example in which FIG. 8 is cut out at a constant engine water temperature. As can be seen from FIG. 9A, when the engine rotational speed is constant, the VTC conversion angular velocity is slowed regardless of whether the engine water temperature rises or falls from the optimum water temperature. This is because the viscosity of the hydraulic oil increases as the engine water temperature decreases. Moreover, it is because the density of hydraulic oil will become coarse when engine water temperature rises. Further, as can be seen from FIG. 9B, when the engine water temperature is constant, the conversion angular velocity of the VTC becomes slow if the engine rotation speed is low. This is because the hydraulic pressure of the hydraulic oil pumped from the oil pump 41 is lowered.

The controller 70 in Step S3, the calculated maximum current I _LMT _ _H and a current lower limit value I _LMT _ _L over a gain 1 / K _p to convert the angular velocity upper limit omega _LMT _ _H and a conversion angular velocity lower limit omega _LMT _ _L To do.

  In step S4, the controller 70 executes a feed forward process. Specific processing contents will be described later.

  In step S5, the controller 70 executes a saturation determination process. Specific processing contents will be described later.

In step S6, the controller 70 executes a feedback process. Specifically, in the feedback compensator B6, the reference response conversion angle θ _sim and the actual conversion angle θ are input, and the feedback current command value I _{com — FB} is output so that the actual conversion angle θ matches the reference response conversion angle θ _sim. To do. If the integral calculation flag F for PID control in the saturation determination process (step S5) is zero, the integral calculation for PID control is stopped. If the integral calculation flag F for PID control is 1, the integral calculation for PID control is executed. .

Step controller 70 in step S7 outputs a current command value I _com by adding the feedforward current command value I _com _ _FF and the feedback current command value I _com _ _FB. The solenoid valve 40 is controlled by the current command value I _com to adjust the conversion angle θ of the VTC 30.

  FIG. 5 is a flowchart showing a subroutine of feedforward processing.

In step S41, the controller 70 performs model matching processing. Specifically, in the model matching control unit B41, a value obtained by subtracting the normative response conversion angle θ _sim from the target conversion angle θ _com is input, and the unrestricted current command value I _com1 is output.

In step S42, the controller 70 performs a restriction process to calculate a feedforward current command value I _{com — FF} . A specific processing routine will be described later.

In step S43, the controller 70 inputs the feedforward current command value I _{com — FF} and outputs the reference response conversion angle θ _sim in the control target model B43.

  FIG. 6 is a flowchart showing a subroutine of restriction processing.

The controller 70 in step S421 determines whether the before limitation current command value I _com1 is smaller than the current limit value I _LMT _ _L. If it is smaller, the process proceeds to step S422; otherwise, the process proceeds to step S423.

In step S422, the controller 70 limits the feedforward current command value I _{com — FF} with the current lower limit value I _{LMT — L.}

Step controller 70 in S423 determines whether the before limitation current command value I _com1 is greater than the current limit I _LMT _ _H. If so, the process proceeds to step S425; otherwise, the process proceeds to step S424.

In step S424, the controller 70 sets the pre-limit current command value I _com1 as the feedforward current command value I _{com — FF} .

In step S425, the controller 70 limits the feedforward current command value I _{com — FF} with the current upper limit value I _{LMT — H.}

  FIG. 7 is a flowchart showing a subroutine for saturation determination.

The controller 70 in step S51 determines whether the current command value I _com is smaller than the current limit value I _LMT _ _L. If it is smaller, the process proceeds to step S52; otherwise, the process proceeds to step S53.

  In step S52, the controller 70 sets the integral calculation flag F for PID control to zero.

The controller 70 in step S53 determines whether the current command value I _com is greater than the current limit I _LMT _ _H. If larger, the process proceeds to step S55, and if not, the process proceeds to step S54.

  In step S54, the controller 70 sets the integral calculation flag F for PID control to 1.

  In step S55, the controller 70 sets the integral calculation flag F for PID control to zero.

Here, in order to facilitate understanding of the effects of the present invention, the comparative example shown in FIG. 10 will be described. In this comparative example, it is then to limit the input signal to the controlled object model B43 at an angular velocity upper limit omega _LMT _ _H and the angular velocity lower limit omega _LMT _ _L calculated by the angular velocity limit value calculator B2. In this case, as described above, it can be seen that there is a delay because the transfer function G _p (s) of the control target model B43 has the first-order lag component (T ₁ +1). Therefore, in the comparative example of FIG. 10, as shown in FIG. 11, the actual conversion angle does not coincide with the norm response conversion angle, and overshoot occurs.

Therefore, in the present invention, the current upper limit value by the angular velocity upper limit omega _LMT _ _H and the angular velocity lower limit omega _LMT _ _L a further current limit value calculator B3 calculated by the angular velocity limit value calculator B2 I _LMT _ _H and a current lower limit value I than it was to limit the input signal to the controlled object model B43 converts the _LMT _ _L. By doing so, as shown in FIG. 12, the actual conversion angle coincides with the reference response conversion angle, the control accuracy of the conversion angle can be increased, and the overshoot can be suppressed.

  Without being limited to the embodiments described above, various modifications and changes are possible within the scope of the technical idea, and it is obvious that these are also included in the technical scope of the present invention.

  For example, FIG. 8 shows an example of the conversion angular velocity upper limit value map. However, since the conversion angular velocity changes according to the discharge pressure of the oil pump, if the discharge pressure sensor can be used, the map of FIG. Will improve. Further, since the conversion angular velocity changes according to the hydraulic oil temperature, when the oil temperature sensor can be used, the accuracy is further improved by using the map of FIG.

It is a figure which shows the structure of one Embodiment of the control apparatus of the variable valve mechanism (VTC) by this invention. It is a block diagram which shows the function regarding the VTC control of a controller. It is a figure explaining the detailed structure of feedforward compensator B4. It is a flowchart of the main routine of VTC control. It is a flowchart which shows the subroutine of a feedforward process. It is a flowchart which shows the subroutine of a restriction | limiting process. It is a flowchart which shows the subroutine of saturation determination. It is a figure which shows an example of a conversion angular velocity upper limit map. It is the figure which cut out the map of FIG. 8 with a fixed engine rotational speed or a fixed engine water temperature. It is a block diagram which shows the structure of a comparative example. It is a figure which shows the control result of a comparative example. It is a figure which shows the effect of this invention. It is a figure which shows an example of the conversion angular velocity upper limit map in case a discharge pressure sensor can be used. It is a figure which shows an example of the conversion angular velocity upper limit map in case an oil temperature sensor can be used.

Explanation of symbols

30 Variable valve mechanism VTC
40 Solenoid valve 70 Controller B2 Angular velocity limit value calculator B3 Current limit value calculator B4 Feed forward compensator B42 Limit model B43 Control target model part B5 Current saturation determiner B6 Feedback compensator

Claims (6)

A control device for a variable valve mechanism that moves a solenoid valve to control the amount of hydraulic oil to adjust the conversion angle,
A model reference type control unit that inputs a target conversion angle and outputs a feedforward control signal for controlling the variable valve mechanism according to the target conversion angle, and calculates a reference conversion angle based on the feedforward control signal A feed forward compensator including a controlled object model unit;
A feedback compensator that outputs a feedback control signal based on the reference conversion angle and the actual conversion angle of the variable valve mechanism;
An angular velocity limit value calculator for calculating a conversion angular velocity limit value of the variable valve mechanism based on an engine operating state;
A current limit value calculator for calculating a current limit value based on the calculated conversion angular velocity limit value;
With
The feedforward compensator further includes a limit model unit that limits an upper and lower limit value of the feedforward control signal that is output from the model reference control unit and input to the control target model unit,
The limit model unit limits the feedforward control signal based on the current limit value calculated by the current limit value calculator ,
The conversion angle of the variable valve mechanism is controlled by the feedforward control signal limited by the limit model unit and the feedback control signal output from the feedback compensator.
A variable valve mechanism control apparatus characterized by the above. A saturation determination unit for determining whether or not a current command value for controlling the variable valve mechanism is in a saturated state based on the current limit value calculated by the current limit value calculator;
If the current command value is not saturated, execute the integral calculation of the feedback compensator,
If the current command value is in a saturated state, the integral operation of the feedback compensator is stopped.
The variable valve mechanism control apparatus according to claim 1 . The angular velocity limit value calculator calculates a conversion angular velocity limit value of the variable valve mechanism based on an engine rotational speed;
The variable valve mechanism control apparatus according to claim 1 or 2 , wherein the variable valve mechanism control apparatus is provided. The angular velocity limit value calculator calculates a conversion angular velocity limit value of the variable valve mechanism based on an engine water temperature.
The variable valve mechanism control apparatus according to claim 1 or 2 , wherein the variable valve mechanism control apparatus is provided. The angular velocity limit value calculator calculates a conversion angular velocity limit value of the variable valve mechanism based on a hydraulic oil temperature for controlling the solenoid valve;
The variable valve mechanism control apparatus according to claim 1 or 2 , wherein the variable valve mechanism control apparatus is provided. The angular velocity limit value calculator calculates a conversion angular velocity limit value of the variable valve mechanism based on an operating hydraulic pressure for controlling the solenoid valve;
The variable valve mechanism control apparatus according to claim 1 or 2 , wherein the variable valve mechanism control apparatus is provided.

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