JP2645266B2 - Engine intake air amount control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for controlling an intake air amount by driving a throttle valve installed in an intake passage to open and close by a step motor for controlling an engine rotation speed. .

(Prior art and its problems) As is well known, a step motor converts an input pulse into a step waveform and applies it to a stator winding to rotate a permanent magnet or a magnetic body in a step-like manner. For example, it is widely used as an actuator in controlling the air-fuel ratio of an automobile engine.

Most of them use a bifilar winding four-phase structure in terms of torque characteristics and are operated by a two-phase excitation method. Here, a device driven by a step motor may need to be driven at a high speed or may need to be precisely controlled in position. It is desired to operate the step motor so that the demand can be satisfied. However, for example, if the step angle is increased to increase the operation speed, there arises a problem that the torque decreases and the control accuracy deteriorates.

On the other hand, a throttle valve installed in the intake passage for controlling the engine rotation speed and controlling the amount of intake air needs to be maintained at an opening that gives the required air amount at that time when the engine is maintained at a certain constant rotation speed. When the rotational speed is changed by acceleration or deceleration, the opening degree must be quickly changed to increase or decrease the intake air amount.

Therefore, when the opening and closing drive of the throttle valve is planned by the stepping motor, if the position controllability of the throttle valve at a constant engine speed is required, the responsiveness of the throttle valve at the time of acceleration or deceleration is deteriorated. As a result, both the position controllability and the opening / closing responsiveness of the throttle valve cannot be satisfied.

(Means for Solving the Problems) According to the present invention, when a step motor is used as an actuator for opening and closing the throttle valve, the requirements are satisfied over all of the magnitude of the torque, the operation speed, and the control accuracy. It is intended to provide a means capable of performing appropriate intake air amount control while achieving both valve position controllability and opening / closing responsiveness, and a step voltage corresponding to an operating state of an engine is provided by an electronic control unit. To apply the voltage to the step motor and maintain the engine at a constant rotational speed, the step motor is operated by the 1-2-phase excitation method or the composite 1-2-phase excitation method to maintain the throttle valve at a predetermined opening and accelerate the engine. Or, to change the rotation speed after deceleration, operate the stepping motor by the two-phase excitation method to open and close the throttle valve, and step when the rotation speed approaches the target rotation speed. Motor 1-
The engine is operated by the two-phase excitation method or the combined 1-2-phase excitation method to control the position of the throttle valve to converge the engine to the target rotational speed.

(Embodiment) An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows that a throttle valve 11 installed in an intake passage 10 of an automobile engine is driven by a step motor 12 to control an intake air amount of an engine as a target device. 1 shows an outline of a system for controlling a required flow rate according to a state. That is, the throttle valve shaft on which the throttle valve 11 is mounted.
A first gear 15 composed of a spur gear is fixed to a shaft end protruding from an intake cylinder 14 of the thirteen, and a second gear composed of a rack meshed with the gear 15 on a guide 16 provided on the intake cylinder 14.
A gear shaft 18 of the rack is directly connected to an output shaft 19 of the step motor 12. The output shaft 19 is screw-coupled to the rotor of the step motor 12 and key-coupled to the casing.The output shaft 19 linearly reciprocates by a distance corresponding to the step angle and the screw pitch, and passes through two gears 17 and 15. The throttle valve 11 is opened and closed.

The stepping motor 12 is applied with a stepping voltage by the electronic control unit 20, and the necessary information such as the throttle valve opening, the engine rotation speed and the like is converted into a continuous electric signal from each detector. A speed command signal that is input to the control unit 20 and arbitrarily specified by the driver is input to the control unit 20 so that an arbitrary engine speed can be set.

FIG. _{2 is} a circuit schematic diagram of windings A ₁ and A ₂ of a stepper motor having a bifilar winding four-phase structure, and shows a power supply voltage applied from a power supply V ₀ and a control unit C and a transistor to which a control signal voltage is applied. A step voltage is applied to each phase Φ1, Φ2, Φ3, Φ4 of a pair of two-phase windings A ₁ , A ₂ by an on / off operation, and the operation is performed by a two-phase excitation method. The status of ON and OFF is as shown in the table below (however, ON is represented by 1 and OFF is represented by 0).

According to the two-phase excitation method, the motor is operated at a speed corresponding to the step angle determined by the step motor to be used, so that there is a characteristic that the operating speed is high and the torque is large. Further, in the above circuit, the on / off status when the operation by the 1-2 phase excitation method is performed is as shown in the following table, and the operation speed and the torque characteristics are lower than those of the operation by the 2 phase excitation method, but the step is smaller. The angle is halved, allowing precise position control.

Transistor on as in the second diagram the normal case the windings A _1, A _2, are those step voltage controlled by off is applied, step further transistors of the windings A _1, A ₂ It is common practice to provide a resistor for improving the characteristics of the motor and reducing the amount of heat generated. FIG. 3 is a schematic diagram of the circuit, in which transistors Tr ₁ , Tr ₂ , Tr ₃ , Tr ₄ , Tr ₅ , Tr ₆ are provided at respective terminals of two pairs of windings A ₁ , A ₂ and a power supply V ₀ and the step voltage is applied to each phase of the windings A ₁ and A ₂ by the on / off operation of the transistor to which the power supply voltage and the control signal voltage applied from the control unit C are applied, as described above. The resistors R ₁ and R ₂ having the above function are provided in parallel with the transistors Tr ₁ and Tr ₂ .

The on / off status of the transistors Tr ₁ ... Tr ₆ when the operation is performed by the composite 1-2-phase excitation method in this circuit is as shown in the table below, and the operation speed and torque characteristics are the operation by the two-phase excitation method. However, the step angle is a quarter, but the position can be controlled more precisely.

FIG. 4 shows the characteristics when the throttle valve 11 in the embodiment of FIG.
The operation by the two-phase excitation method or the composite 1-2-phase excitation method is represented by L,
Let H be the operation by the two-phase excitation method. When the opening of the throttle valve 11 is maintained at a low opening and the engine is rotated at a low speed, the operation of the step motor 12 is performed by L. Next, when accelerating and raising the engine to the target rotational speed, it is necessary to open the throttle valve 11 rapidly. Therefore, the operation of the stepping motor 12 is performed by H, and when approaching the target rotational speed, the throttle valve 11 is operated.
It is necessary to precisely control the position to the required opening degree, so the operation of the stepping motor 12 is performed by L to converge the engine to the target rotation speed. During deceleration, the throttle valve 11 is driven by the same means as described above.

(Effects of the Invention) As described above, according to the present invention, the two-phase excitation of the step motor that opens and closes the throttle valve is performed according to the step voltage sent from the electronic control unit based on various information that informs the operating state of the engine. Method, 1-2 phase excitation method or composite 1
Because it is performed by one of the two-phase excitation method,
The throttle valve is opened and closed at a high speed to perform rapid acceleration or deceleration, or is precisely controlled to maintain a desired constant rotational speed, and is suitable for any state of an engine placed in various situations. The intake air amount can be controlled.

[Brief description of the drawings]

FIG. 1 is a front view of an embodiment of the present invention, FIGS. 2 and 3 are circuit schematic diagrams of a step motor, and FIG. 4 is a control characteristic diagram of the embodiment of FIG. , 11 ... Throttle valve, 12 ... Step motor,
A ₁ , A ₂ …… winding,

Claims (1)

(57) [Claims] The throttle valve of the engine intake passage is driven by a step motor to which a step voltage corresponding to the operating state of the engine is applied by an electronic control unit to control the intake air amount to the required engine flow rate. To maintain a constant rotation speed, the stepping motor is operated by a 1-2-phase excitation method or a combined 1-2-phase excitation method to maintain the throttle valve at a predetermined opening and accelerate or decelerate the engine to change the rotation speed. To operate the motor, the stepping motor is operated by the two-phase excitation method to open and close the throttle valve.
A method for controlling an intake air amount of an engine, wherein the engine is operated by a two-phase excitation method to control the position of a throttle valve to converge the engine to a target rotational speed.