JPH01232146A - Control device for engine - Google Patents

Abstract

PURPOSE:To prevent a radio noise from increasing by deciding a duty pulse frequency for whether or not it is placed in a radio frequency region and changing the duty pulse frequency so as to be placed out of this region when the duty pulse frequency is placed in the radio frequency region. CONSTITUTION:A control amount determining means A determines a control amount of an output adjusting means F by an electric driving means E, and a duty pulse generating means B generates a duty pulse of duty ratio in accordance with the control amount and drives the output adjusting means F through the electric driving means E, controlling an operative condition of an engine. Here a region decision means D decides a duty pulse frequency for whether or not it is placed in a radio frequency region, when the duty pulse frequency is placed in the radio frequency region, the duty pulse changes its period so as to be placed out of this region by a period changing means C. On the contrary, when the duty pulse frequency is placed out of the radio frequency region, the duty pulse sets its period to a normal value. In this way, an increase of radio noise, particularly an AM band noise, can be effectively prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine throttle control device that controls the drive of output adjusting means such as a throttle valve through an electric actuator.

(Prior Art) In the engine of a vehicle, an output adjustment means such as a throttle valve is generally mechanically connected to an accelerator pedal via a wire. It is uniquely determined by the amount of pedal depression, that is, the amount of accelerator operation. However, in this type of control where the accelerator operation amount and the throttle position have a unique relationship, that is, an l-to-l correspondence, for example, even when a particularly high output is required, such as during acceleration, the accelerator is simply depressed. Since only the output corresponding to the amount can be obtained, it is difficult to respond accurately to various required driving conditions.

Therefore, we attempted to achieve engine control that always meets the driver's wishes by connecting the accelerator pedal and throttle valve via an electric actuator, and operating the actuator with characteristics that correspond to each required driving state. Various things have been proposed in the past. For example, in the vehicle accelerator control device described in Japanese Patent Application Laid-Open No. 60-198343, a plurality of functional characteristics between the accelerator operation amount and the throttle valve opening are set, and one of them is set based on the accelerator operation speed. The target throttle valve opening degree is determined in accordance with the selected function characteristics.

By the way, such an electric throttle valve control device generally uses a duty pulse to drive a DC motor to open and close the throttle valve. In this case, the frequency of the duty pulse is, for example, ,
The frequency is set to approximately 15KHz. However, in conventional devices that perform such duty control, a problem sometimes arises in that radio noise, especially AM band noise, increases. This radio noise is caused by, for example, when the frequency of the duty signal is about 15 KHz and the duty ratio becomes a small value such as 5% or 10%, the pulse width of the ON part of the duty signal becomes AM
It falls into the frequency range, and the duty ratio is 90%.
This is caused by the length (pulse width) of the OFF portion of the duty signal entering the AM frequency range when it reaches 95%. As a means to avoid such an increase in radio noise, it is possible to set the frequency of the duty signal lower or, conversely, to increase or decrease the frequency of the frequently occurring pulses. Of course it is possible, but
If the frequency of the duty signal is set too low, control responsiveness will deteriorate and hunting will inevitably occur in the motor drive current, and if the frequency of the duty signal is set too high, the Since the frequency of the utility pulse itself becomes close to the AM frequency range, neither method can be effective.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to prevent radio noise from increasing due to a duty pulse for controlling the drive of an engine output adjustment means. .

(Structure of the Invention) The present invention makes it possible to suppress radio noise while ensuring overall control responsiveness and stability by changing the cycle of the duty signal only in a specific area. The overall configuration is as shown in FIG. That is, the engine control device according to the present invention includes:
output adjustment means for adjusting the output of the engine; control amount determining means for determining the control amount of the output adjustment means; and duty pulse generation for generating a duty pulse having a duty ratio according to the output of the control amount determination means. means, electrical driving means for driving the output adjusting means under control by the duty pulse, region determining means for determining whether the frequency of the duty pulse falls within a radio frequency region, and the region determining means The present invention is characterized by comprising a period changing means for changing the period of the duty pulse so that the duty pulse generated by the duty pulse generating means falls outside the range based on the output signal of the duty pulse generating means.

(Function) The controlled amount determining means determines the controlled amount of the output adjusting means by the electrical driving means, and the duty pulse generating means generates a duty pulse with a duty ratio corresponding to this controlled amount to generate the electrical drive. Output to means.

The region determining means determines whether the duty pulse frequency is within the radio frequency region.

When the duty pulse frequency is within the radio frequency range, the cycle changing means changes the cycle of the duty pulse so that it goes outside this range. If the duty pulse frequency is outside the radio frequency range, the duty pulse period is set to a normal value.

FIG. 2 schematically shows the relationship between the duty ratio and the AM band frequency component when the frequency of the duty pulse is fixed. As shown in this figure, when the frequency is fixed, when the duty ratio is within the reference range, almost all A
Does not include M-band frequency components, but duty ratio is 0%
Conversely, when it approaches 100%, the AM band frequency component increases rapidly, making it easy for radio noise to occur. In other words, as the duty ratio decreases, the pulse width of the duty pulse approaches the AM band frequency, and conversely, as the duty ratio increases, the width of the off portion of the duty pulse approaches the AM band frequency. Radio noise will increase in certain areas. The duty ratio region in which such radio noise increases varies depending on the cycle of the duty pulse. In other words, since the pulse width for the same duty ratio changes as the period changes, the duty ratio and A
The relationship with the M band frequency will change. therefore,
Even if the duty ratio is in a range where radio noise is likely to occur if the cycle is normal, by changing the cycle of the duty pulse, it is possible to set the duty pulse to be outside this range.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 3 is an overall diagram of a servo system according to an embodiment of the present invention applied to control of a throttle valve.

In this embodiment, the throttle valve l is connected to a motor 3 (throttle actuator) via a wire 2 (throttle cable), and is driven to open and close by rotating the motor 3 in forward and reverse directions.

The control system for the motor 3 includes a throttle controller 4, a servo controller 5, and a drive circuit 6.

The throttle controller 4 calculates a target value for the throttle opening based on signals such as the output signal of the accelerator sensor 8 that detects the amount of depression of the accelerator pedal 7, the engine speed, the vehicle speed, the slope, the steering angle, and the water temperature. An abnormal signal is determined and two signals, a throttle valve target opening signal and a motor cut signal, are output to the servo controller 5.

The servo controller 5 is a microprocessor (CPU).
) 9, and an AD converter 10 is installed around the CPU 9.
．． ROMI 1 and RAM 12 are attached. C
The PU 9 is also provided with a counter 13 for performing pulse conversion (PWM) on the CPU internal value (duty). The reference clock of the counter 13 is a signal from an external crystal oscillator 14 divided by a flip-flop 15, and has a frequency of about 4 MHz. The basic frequency of the counter 13 is approximately 15 KHz based on I/256 (duty is 8 bits) with a 4 MHz clock. The servo controller 5 also includes a logic circuit 16 that receives three signals (to be described later) as input, and is configured to control the drive circuit 6 using four outputs of the logic circuit 16.

The drive circuit 6 includes four transistors T, 1 . T, 2. T, 3. Tr
It is composed of 4. The motor 3 consists of a first transistor T,l (PNP) and a fourth transistor T,4
(NPN') are both electrically conductive, the second transistor Tr2 (
NPN) and the third transistor (PNP) both conduct in the reverse direction, that is, the throttle valve! Rotate in the closing direction.

A position sensor 17 is attached to the motor 3 to detect the actuator position.

The target opening signal of the throttle valve l outputted by the throttle controller 4 is analog, and is converted into a digital signal by the AD converter 10 and sent to the CPU 9.

Similarly, the output of the position sensor 17, which detects the throttle valve opening based on the actuator position, is also AD converted and input to the CPU 9. The CPU 9 compares the output value (throttle valve opening) of the position sensor 17 with the target opening, and performs control (P, I) consisting of three terms: proportional, integral, and differential.
.

D control) calculates the current value and current direction to be passed through the motor 3. The calculated current value is then converted into an 8-bit duty value, which is correctly converted by the counter 13 and output. The logic circuit 16 contains this pulse-converted duty signal, a current direction signal corresponding to the calculated current direction, and a current cut signal outputted by the CPU in response to the motor cut signal from the throttle controller 4. Three signals are input.

The logic circuit 16 is composed of seven logic elements, and the four output terminals of the logic circuit 16 are connected to the four logic elements that constitute the drive circuit 6.
The transistor Tr1. T, 2. T.

The bases of 3, T, and 4 are connected to each other.

The first transistor T,1 is controlled by a logic circuit in which an exclusive OR circuit inverts the output of an AND circuit which receives two inputs, a duty signal and a current direction signal. In other words, when both the duty signal and the current direction signal are at high level (1), this transistor T,
The base of l becomes low level and conducts. Also, the fourth
The transistor Tr4 is controlled by the output of an AND circuit that receives two inputs, a current direction signal and a current cut signal, and when both of these signals are at high level (1), the base becomes high level and conducts. Therefore, as long as the current cut signal is high (1) and the current direction signal is high (1), the fourth transistor Tr4 remains on, and the duty signal exclusively controls the rotation of the motor 3 in the opening direction. It will be controlled.

On the other hand, the third transistor T,3 receives the output of an AND circuit which has one input as the duty signal and the other input as a signal obtained by inverting the current direction signal in the exclusive OR circuit. It is controlled by a logic circuit that inverts the signal at . That is, when the duty signal is at a high level (1) and the current direction signal is at a low level (0), the bases of the transistors T and 3 are at a low level and conductive. Moreover, the second transistor T,
2 uses the inverted signal of the current direction signal as one input,
It is controlled by the output of an AND circuit whose other input is the current cut signal. That is, when the current direction signal is at low level (0) and the current cut signal is at high level (1), the base of this transistor Tr2 becomes high level and conducts.

Therefore, as long as the current cut signal is high (1) and the current direction signal is low (0), the second transistors T, 2
remains conductive, and the rotation of the motor in the closing direction is controlled exclusively by the duty signal. Further, when the current cut signal is at a low level (0), the fourth and second transistors Tr4 and Tr2 are non-conductive, and the motor 3
No current flows through.

Table 1 Table! There are three signals (DUTY: duty signal, DI
R: current direction signal, MCUT: current cut signal) and the logic of each transistor (T, 1.T, 2.Tr3, T, 4) are shown.

According to this logic, for the rotation of the motor in the opening direction, two transistors T, the first and the fourth.

1, T, 4, only the first transistor T, 1, and for the rotation of the motor in the closing direction, two transistors, third and second -, T, 3. Only one of the transistors T, 2 is controlled, such as the third transistor T, 3. Therefore, the problem of asynchronization between the two transistors does not occur, and reliable duty control is performed. Then, the first and fourth transistors T, l, T, 4 and the third
and a second transistor T, 3. Since T and T2 are not conductive at the same time, even if the CPU goes out of control and the logic of the output port is not compensated, the drive circuit 6 and motor 3 will not be burnt out due to a short circuit. Further, since the drive control of the motor 3 is performed via such a logic circuit I6, the burden on the software of the CPU is reduced.

In this embodiment, the fundamental frequency of the duty pulse output by the PWM counter 13 is set to approximately 15K I-1z. That is, the counter 13 is controlled to output one pulse when it counts 256 4 MHz reference clocks as described above. Therefore, the duty ratio is used to determine whether or not the fundamental frequency is a region where radio noise is likely to occur. Accordingly, the cycle is lengthened, but this cycle can be changed by changing the value of the counter 256, for example, 256.
If 6 is doubled to 512, the duty pulse period will be doubled. If the cycle of the duty pulse is changed in this way, the duty ratio region in which radio noise is likely to occur changes, so even if the duty ratio is the same, the generation of radio noise will be reduced.

FIG. 4 to FIG. 1θ show flowcharts for executing the control of this embodiment.

First, FIG. 4 shows the main routine. The main routine consists of five subroutines S.t.S.5.

Start and initialize first (S.1). Then, the input signal from the position sensor 17 is sampled (S
・2). And based on that, P.

1. Feedback calculation of current value is performed by D control (S.3). Then, the PWM cycle, that is, the duty cycle is calculated and processed (S4).

Finally, the motor cut signal is checked to control whether or not to cut the motor current (S.5).

The first subroutine 5-1 (FIG. 5) starts and first sets each port as input or output. Next, the timer and PWM for interrupt processing
Initialize the counter.

Next, various registers used in calculations are initialized, and the process returns.

Next, the second input signal sampling subroutine S.2 shown in FIG. 6 will be explained. This subroutine starts, performs A/D conversion of the actuator position signal by the position sensor 17, and stores the data as a value TVOA. Next, the throttle valve target opening signal is A/D converted and the data is stored as a value TVOT. This allows all three analog signals to be converted into A/D
converted.

Next, the third feedback calculation subroutine S
・In 3 (Fig. 7), start, first read the output value TVOA of the position sensor 17, then set the target opening T
Read the VOT value.

Then, the deviation ΔTV between the sensor output value TVOA and TVOT
Calculate O. Furthermore, the current sensor output value TVOA of the position sensor 17 and the previous sensor output value TVOAL are subtracted to calculate the moving speed ΔSPD of the actuator position. Further, the previously calculated deviation ΔTVO is added to the previous ■ value integrated value ΣΔTVO to obtain the I value integrated value ΣΔTVO.

Next, to the value obtained by multiplying the calculated deviation ΔTVO by the feedback constant KP of the proportional term, add the value obtained by multiplying the I value integrated value ΣΔTVO by the feedback constant Kl of the integral term, and from this, add the value obtained by multiplying the I value integrated value ΣΔTVO by the feedback constant Kl of the integral term, and from this, add the value obtained by multiplying the I value integrated value ΣΔTVO by the feedback constant Kl of the integral term, and from this, add the value obtained by multiplying the I value integrated value ΣΔTVO by the feedback constant Kl of the integral term. The motor current value FB is obtained by subtracting the product multiplied by the feedback constant KD.

Next, the current direction is determined depending on whether the current value FB is positive. To set the flag for interrupt processing, first, if FB is positive, the current direction flag PDIR, that is, the boat output level flag FDIR that sets the direction of the motor current, is set to 0 (opening direction). shall be. Also, if FB is not positive, FD
Set IR to 1 (closed direction).

Next, for duty conversion, the absolute value of the current value FB is determined, and the current-duty conversion coefficient K du
The duty value is obtained by multiplying by ty.

Finally, the previous value TVOAL of the sensor output value used for calculating the differential term is updated to the current TV6A.

Next, the fourth PWM cycle calculation/processing subroutine S-4 shown in FIG. 8 starts and first reads the duty value DUTY. Then, depending on whether the DUTY is smaller than the determination value Pw, it is determined whether the radio noise generation area exists.

If it is not smaller than D U T Y h < P w, nothing will be done because it is outside the noise generation range, but
When DUTY is smaller than Pw, next, PW
To calculate the period TPWM of M, the initial value Tba of the PWM period. . The product obtained by multiplying A by the coefficient Kc is defined as the PWM period TPWM. The coefficient Kc is the judgment value Pw as DUTY.
This is the value divided by .

Next, to set the PWM counter, TPWM is written into the PWM cycle register of the PWM counter.

FIG. 9 shows the fifth current cut subroutine 3 and 5.
It shows. In this routine, the current cut input from the throttle controller 4 is first read. Then, it is determined whether or not the current is to be cut, and if it is determined that the current is to be cut, the CPU 9's current cut port (M
CUT) to low (current cut) to ensure that the transistor does not conduct, and when the current is not cut, set the current cut port to high (current conduction).

This completes the main routine of this embodiment, but apart from this there is a timer interrupt processing routine shown in FIG. This interrupt processing is started at regular intervals (1 to 2n+s), and when started, it first reads the interrupt processing cycle (T I NT) and then sets the next interrupt time. So, at this time, the period TINT
and stores it in the interrupt register.

Next, to read the PWM duty (DUTY), read the value DUTY obtained in S.3 of the main routine, and to set the PWM timer, store the value DUTY in the PWM timer register. . In other words, write to the counter. S-1
Since the counter has been initialized, the counter outputs a pulse according to the value of DUTY from the time of writing.

Next, the current direction is determined by looking at the current direction flag FDIR set in S.3 of the main routine. And F
If DIR is 0, the DIR boat is set to a high level (in the open direction), and if FDIR is not 0, the DIR boat is set to a low level (in the closed direction).

In the above embodiment, radio noise is suppressed on the side where the duty ratio is small, but the period is also changed when the duty ratio is 90% or more, and the pulse is turned off. It is also possible to suppress radio noise in both bands by preventing the length of the part from falling into the AM band frequency range.

Further, as the feedback signal, it is of course possible to use the output of a throttle sensor that directly detects the throttle position instead of the actuator position as in the above embodiment.

Further, in the above embodiment, the motor drive circuit is controlled via a logic circuit, but the present invention
It is also possible to apply the present invention to a device in which a drive circuit is directly controlled by the output of U.

Furthermore, the present invention is applicable not only to throttle valve control but also to engine control using other output adjustment means.

(Effects of the Invention) Since the present invention is configured as described above, it is possible to effectively prevent increase in radio noise, especially AM band noise, due to duty pulse while ensuring responsiveness and stability of engine control. can do.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the present invention, FIG. 2 is a characteristic diagram explaining the present invention in detail, and FIG. 3 is an overall diagram of an embodiment of the present invention.
FIG. 4 to FIG. 1O are flowcharts for executing control in this embodiment. ! = Throttle valve, 3: Motor (actuator), 4
: Throttle controller, 5: Servo controller,
6: Drive circuit, 9: Microprocessor (CPU), 1
7: Position sensor. Agent Patent Attorney Jun Shinfuji - Figure 1 Figure 2 M. B1 Ayu Aie Figure 9 S・5 Figure 10

Claims (1)

[Claims] (1) Output adjustment means that adjusts the output of the engine, control amount determining means that determines the control amount of the output adjustment means, and duty pulse that generates a duty pulse with a duty ratio according to the output of the control amount determination means. generating means; electrical driving means for driving the output adjusting means under control by the duty pulse; region determining means for determining whether the frequency of the duty pulse falls within a radio frequency region; An engine control device comprising: cycle changing means for changing the cycle of the duty pulse so that the duty pulse generated by the duty pulse generating means falls outside the range based on an output signal.