JPH0465229B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an idle rotation control device mainly used in automobile engines.

(Prior art) Recently, automobile engines have been designed to suppress the number of rotations during idling as much as possible to improve fuel efficiency, and to prevent engine stalling when external loads such as coolers are applied, or to prevent engine stalling during cold starting. For the purpose of promoting warm-up of the engine, an idle rotation control device is provided that controls the idle rotation speed according to the operating state.
This idle rotation control device includes a bypass passage that bypasses a throttle valve in the intake passage, and a flow rate control valve on the bypass passage, and controls the opening degree of the valve to control the amount of intake air supplied to the engine. By adjusting the
This configuration performs feedback control so that the engine speed converges to a target idle speed that is set according to the operating state at that time (external load operating state, cooling water temperature, etc.).

However, in this device, for example,
As shown in Publication No. 160138, the actuator for controlling the opening degree of the flow control valve is a pressure-responsive actuator that displaces the valve body of the flow control valve via a diaphragm in response to the pressure introduced into the pressure chamber. A device is used and is provided with pressure control means for regulating the pressure introduced into the pressure chamber of the device. Then, a control signal with a value determined based on the deviation between the target idle speed set according to the operating state of the engine and the actual engine speed is intermittently sent to this pressure control means at predetermined time intervals. configured to send.

However, according to the above configuration, after the pressure control means is activated, the pressure in the pressure chamber of the pressure response device is adjusted, and the pressure response device is displaced accordingly to adjust the opening degree of the flow rate control valve. Since there is a certain amount of time delay before the pressure control is performed, the following problem arises in relation to the output time interval of the control signal to the pressure control means.

In other words, as shown in FIG. 1, a certain control period t ₁
For example, when the target idle speed T changes due to the action of an external load and a deviation _H1 occurs between it and the actual engine speed N, the pressure control means responds to the deviation _H1 in the control period _t1 . In response to the control signal S (D ₁ ) of the control value D ₁ , the pressure introduced into the pressure chamber of the pressure-responsive device is adjusted, which adjusts the opening degree of the flow rate control valve and adjusts the actual opening degree. Before engine speed N converges to target speed T, that is, there is still a deviation between both speeds T and N.
When H ₂ is present, the control signal S(D ₂ ) of the control value D ₂ corresponding to the deviation H ₂ is input again to the pressure control means in the next control period t ₂ . Therefore, the first control signal S(D ₁ ) itself has a deviation
A signal with a value that eliminates H ₁ , and this signal S
(D ₁ ) alone, after the operation delay time L of the pressure-responsive device has elapsed, the actual rotation speed N matches the target rotation speed T, as shown by the chain line, but before that, the control signal S (D ₂ ) is output, so the pressure-responsive device or flow control valve becomes over-controlled. As a result, the actual engine speed N overshoots the target engine speed T, and hunting occurs accordingly.

One possible solution to this problem is to make the output time interval of the control signal sufficiently longer than the operation delay time of the pressure-responsive device. is delayed, causing inconveniences such as engine stalling.

(Object of the invention) The present invention provides an engine idle rotation control device,
In particular, by adjusting the pressure introduced into the pressure chamber of the pressure-responsive device using a pressure control means to which a control signal is input at predetermined time intervals, the idle speed can be adjusted to the target speed according to the operating state of the engine. In a device that performs feedback control, it is possible to solve the problem of overcontrol due to the delay in the operation of the pressure response device as described above, prevent overshoot or hunting with respect to the target rotation speed, and perform stable control of idle rotation. purpose.

(Configuration of the Invention) An engine idle rotation control device according to the present invention is configured as follows in order to achieve the above object.

That is, as shown in FIG. 2, there is an engine rotation sensor A that detects the engine rotation speed, and a pressure response device B that is displaced according to the pressure introduced into the pressure chamber B'.
, a flow rate control valve C that is connected to the pressure response device B and adjusts the amount of intake air supplied to the engine by displacement; and a flow rate control valve C that adjusts the amount of intake air supplied to the engine by being displaced; The pressure control valve D adjusts the engine speed, and the output signal of the engine speed sensor A and the output signal of the target idle speed setting means E that sets the target idle speed according to the operating condition are received, and the actual engine speed is adjusted. a rotation speed comparison means F that compares the rotation speed with a target idle rotation speed and outputs a deviation value thereof; and a pressure control valve that receives the output of the rotation speed comparison means so that the actual engine rotation speed converges to the target rotation speed. and control signal output means G for outputting a control signal to D, and the control signal output means G outputs the control signal at predetermined time intervals, and when the target idle rotation speed changes, after detecting the change. At the first processing point, a control signal with a control value corresponding to the deviation value output from the rotation speed comparison means is output, and at the next processing point, a value corresponding to the deviation value at that point is output as the engine rotation speed. The control signal is configured to output a control signal having a control value corrected in a direction in which a change in the value is reduced.

According to such a configuration, when the target idle rotation speed T changes as shown in FIG.
At t ₁ , the control signal S (D ₁ ) of the control value D ₁ corresponding to the deviation value H ₁ is output, as in the conventional case, and at the control period t ₂ , which is the next processing time, the deviation value at that time is output. The control signal S (D ₂ ) of the control value D ₂ is output, which is corrected in a direction in which the change in engine speed decreases more than the value corresponding to H ₂ , that is, a value smaller than the value corresponding to the deviation value H ₂ . For example, by setting this control value _D2 to zero, the actual engine speed N is converged to the target idle speed T without overshooting or hunting.

The control value of the above control signal may be a value that corresponds to the deviation between the target idle speed and the actual engine speed, or it may be a value that corresponds to the deviation between the target idle speed and the actual engine speed. In some cases, a target position of the valve body C' in the valve C is calculated, and a value corresponding to the deviation between the target position and the actual position is set.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

As shown in FIG. 3, the engine 1 has an intake valve 2.
An intake passage 5 and an exhaust passage 6 are provided which respectively communicate with the cylinder 4 via an exhaust valve 3.
From the upstream side, there is an air cleaner 7, an air flow meter 8, a fuel injection nozzle 9, and a throttle valve 1.
0 is provided.

Further, a throttle valve 10 is provided in the intake passage 5.
Bypass passage 1 that communicates the upstream side and downstream side of
1, a flow control valve 12 is installed on the passage 11, and a pressure responsive device 13 is provided as an actuator of the flow control valve 12. This pressure response device 13 is configured such that a diaphragm 13b is displaced against a spring 13c in response to pressure (negative pressure) introduced into a pressure chamber 13a. The flow control valve 1 is connected to the diaphragm 13b.
The valve bodies 12a in 2 are connected, and the valve bodies 12a are connected to each other.
By displacing integrally with the diaphragm 13b, the opening degree of the flow rate control valve 12 is adjusted in accordance with the pressure within the pressure chamber 13a.

On the other hand, in the pressure chamber 13a of the pressure response device 13,
Atmospheric pressure is introduced from the upstream side of the throttle valve 10 in the intake passage 5 through the atmospheric pressure introduction passage 14, and intake negative pressure is introduced from the downstream side of the throttle valve 10 through the negative pressure introduction passage 15. are being synthesized and introduced. In that case, the atmospheric pressure introduction passage 14 and the negative pressure introduction passage 1
5 is equipped with an atmospheric pressure control valve 16 and a negative pressure control valve 17, respectively, and the amount of atmospheric pressure and intake negative pressure introduced is controlled by the opening and closing operations of these valves 16 and 17. The combined negative pressure introduced into the pressure chamber 13a of the device 13 is adjusted.

The atmospheric pressure control valve 16 and the negative pressure control valve 17 are controlled to open and close by a control signal a sent from a control unit 18 constituted by a microcomputer.

This control unit 18 receives a rotation signal b from an engine rotation sensor 19 that detects the rotation speed of the engine 1, a load signal c that indicates the operation or stop of an external load 20 such as a cooler, and a signal in the water jacket around the cylinder 4. The water temperature signal d from the water temperature sensor 21 detects the cooling water temperature of the crankshaft (not shown) via the distributor 22.
A timing signal e is output from the timing sensor 23 that detects the rotation angle of the crankshaft, for example, every half rotation of the crankshaft, a position signal f is output from the position sensor 24 that detects the displacement of the diaphragm 13b in the pressure response device 13, and the air flow is The air flow rate signal g from the meter 8, the throttle opening signal h from the throttle opening sensor 25 that detects the opening of the throttle valve 10, and the oxygen concentration signal from the oxygen concentration sensor 26 installed in the exhaust passage 6. i is input. The control unit 18 also outputs a fuel control signal j to the fuel injection nozzle 9.

Next, the operation of the control unit 18 will be explained according to the flowchart shown in FIGS.

The control unit 18 is basically the fourth
Fuel control is performed according to the main routine shown in the figure. That is, operation starts when _the ignition switch is turned on, and after initializing various conditions in step _P1 , the engine rotation signal b, load signal c, water temperature signal d, Various parameters indicating the operating state of the engine are read in using the position signal f, air flow rate signal g, throttle opening signal h, oxygen concentration signal i, etc., and necessary processing such as A-D conversion is performed on these parameters. Then, in step _P3 , the engine speed, cooling water temperature,
The fuel injection amount is calculated based on values such as air flow rate, throttle opening, oxygen concentration, etc., and a fuel control signal j corresponding to the calculated injection amount is sent to the fuel injection nozzle 9. As a result, an amount of fuel suitable for the operating condition of the engine is injected from the fuel injection nozzle 9 into the intake passage 5 (step P ₄ ).

However, if the timing signal e is input while the fuel control according to this main routine is being performed, the control unit 18 temporarily stops the fuel control and executes the subroutine for idle rotation control shown in FIG. .

In this subroutine, the control unit 18 first determines in step _Q1 whether or not the engine 1 is in an idling operating state based on the engine rotation signal b and the throttle opening signal h. If the engine is not in the idling state, the process returns to the main routine shown in Figure 4 and the fuel control is performed again. However, if the engine speed is below the predetermined number of revolutions and the throttle opening is zero, it is determined that the engine is in the idling state. Then execute steps Q ₂ and Q ₃ . In step _Q2 , the diaphragm 13 in the pressure response device 13 is adjusted based on the position signal f.
The actual position (hereinafter referred to as actual position) Nn of b is calculated. In addition, in step _Q3 , the target idle speed corresponding to the load condition and cooling water temperature, etc. indicated by the load signal c and water temperature signal d is compared with the actual engine speed indicated by the engine speed signal b, and the engine speed is determined. Target position corresponding to deviation
Calculate Tn. Then, in the following steps, the control value D of the control signal a to be output is calculated based on the above-mentioned actual position Nn and target position Tn.
The control values D _o-1 , D _{o-2 ,} etc. calculated at the previous processing time and the time before the previous processing are used to calculate Dn.

That is, if the previous control value D _{o -1} = 0, steps Q ₄ to Q ₆ are executed, and the control value Dn is calculated according to the first equation: Dn = Tn - Nn. Here, Tn,
Nn is the target position and actual position at the time of the processing.

Furthermore, if the previous control value D _o-1 ≠ 0 and the control value before the previous one D _o-2 = 0, steps Q ₄ and Q ₅ to step Q ₇ are executed, and the second equation: Dn = Tn - ( The control value Dn is calculated according to N _o-1 + D _o-1 ).

Furthermore, if the previous control value D _o-1 ≠ 0 and the control value before the previous one D _o-2 ≠ 0, steps Q ₄ and Q ₅ to step Q ₈ are executed, and the third equation: Dn = Tn - ( The control value Dn is calculated according to N _o-2 + D _o-2 + D _o-1 ).

Then, in step _Q9 , the first, second,
Control value Dn calculated by one of the third equations
is converted into a duty ratio, and this is converted into the control signal a
(Dn) is sent to the atmospheric pressure control valve 16 or negative pressure control valve 17 shown in FIG.

In this case, if the control value Dn is a positive value, that is, the actual position Nn of the diaphragm 13b in the pressure response device 13 is the target position Tn.
If it is smaller, the control signal a (Dn) is sent to the negative pressure control valve 17, which is opened at a duty ratio corresponding to the magnitude of the control value Dn, and the pressure responsive device is removed from the negative pressure introduction passage 15. 13
Intake negative pressure is introduced into the pressure chamber 13a. Therefore, the combined negative pressure value of the pressure chamber 13a increases,
The diaphragm 13b is displaced upward in the drawing against the spring 13c, and the actual position Nn of the diaphragm 13b is converged to the target position Tn. At this time, the valve body 12a of the flow control valve 12 is also displaced upward in the drawing, that is, in the direction in which the opening degree increases, and the amount of bypass air passing through the bypass passage 11 and being supplied to the cylinder 4 increases.
Engine speed increases. Further, when the control value Dn is a negative value, that is, when the actual position Nn of the diaphragm 13b is larger than the target position Tn, a control signal a (Dn) is sent to the atmospheric pressure control valve 16, and the valve 16 is controlled. Value Dn
is opened at a duty ratio corresponding to the magnitude of , atmospheric pressure is introduced into the pressure chamber 13a of the pressure response device 13, and the resultant negative pressure value within the pressure chamber 13a becomes small. As a result, the diaphragm 13b is displaced downward in the drawing, and the actual position Nn is converged to the target position Tn. In this case, the opening degree of the flow control valve 12 becomes smaller, the amount of air passing through the bypass passage 11 decreases, and the engine speed decreases.

After outputting the control signal a(Dn) as described above, the control unit 18 converts the current control value Dn into the previous control value D _{o -} in order to calculate the next control value Dn in step _Q10 . ₁ , the previous control value
D _o-1 is set to the control value D _o-2 from the time before last, the current actual position Nn is set to the previous real position No _-1 , and the previous real position No _-1 is set to the real position No _-2 from the time before last.
Replace the memory data respectively.

In this way, one cycle of idle rotation control is completed, and the control unit 18 again performs the fuel control shown in FIG. 4. From then on, the same idle rotation control is performed every time the timing signal e is input. It is.

Next, it will be explained specifically how the actual position of the diaphragm 13b in the pressure response device 13 changes in relation to the operation delay time when the idle rotation control as described above is repeatedly performed. In this case, the input time interval of the timing signal e, that is, the control period t, is practically the time required for half a revolution of the crankshaft, and the operation delay time L of the pressure responsive device with respect to this time interval t is as follows: In fact, there is a relationship of t<L<2t.

First, as shown in FIG. 6, in a state in which the actual position N ₀ in a certain control period _t 0 substantially coincides with the target position T ₀ due to the previous idle rotation control, for example, an external load starts operating. Assuming that, in the control period t ₁ immediately after that, the target position T ₁ calculated in step Q ₃ of the idle rotation control routine changes from the previous value T ₀ ,
Actual position of current period t ₁ calculated in step Q ₂
A deviation H=T ₁ −N ₁ occurs between N ₁ (=N ₀ ).
In this case, the target position and the actual position matched until the previous time, and the control value D ₀ (D _o-1 ) calculated in the previous control cycle t ₀ was zero, so _the first The current control value, D ₁ =T ₁ -N ₁ , is calculated according to the formula: Dn-Tn-Nn, and the corresponding duty ratio control signal a(D ₁ ) is output.

This control value D ₁ has a magnitude corresponding to the deviation H, and the deviation H is canceled after the operation delay time L of the pressure response device 13 has elapsed with only the control signal a(D ₁ ). However, the next control period t ₂ comes before that. In that case, if the conventional control method is used, the control value D ₂ at period t ₂ is the deviation at that time.
Although the value corresponds to H', the control value _D2 is corrected as follows.

That is, at control time _t2 , the previous control value _D1
(D _o-1 )=H≠0, and the control value D ₀ before the previous one
Since (D _o-2 )=0, the second equation in step _Q7 :
Dn=Tn-(N _o-1 + D _o-1 ) is applied. In this equation, current target position Tn = T ₂ , previous actual position N _o-1 = N ₁ , previous control value D _o-1 =
Because it is D ₁ and the target position does not change.
Since T ₂ = T ₁ and the previous control value D ₁ = T ₁ - N ₁ , the current control value D ₂ is calculated from the second equation above as D ₂ = T ₂ - (N ₁ + D ₁ ) = T ₂ −(N ₁ +T ₁ −N ₁ )=T ₂ −T ₁ =0. In other words, in the current control period t ₂ ,
The control value D ₂ is set to zero even though the target position T ₂ and the actual position N ₂ do not yet match. This prevents overcontrol caused by outputting a control signal with a control value corresponding to the deviation H' in the control period _t2 , and prevents overshooting or hunting of the actual position relative to the target position.

Furthermore, in the next control period t ₃ , the previous control value D ₂ (D _o-1 )=0, so the first equation: Dn=Tn
-Nn is used, but at this point the operation delay time L of the pressure response device 13 has elapsed and the actual position is
Since it has converged to T ₃ (=T ₁ ), the control value D ₃ is set to D ₃ =T ₃ −N ₃ =0, and the control ends.

Further, to explain the example shown in FIG. 7, in the control period _t1 , the target position _T1 changes from the previous value _T0 due to a change in external load, etc., and a difference _H1 between it and the current position _N1 occurs. shall be deemed to have occurred. In this case, first, the control value D ₀ of the previous control period t ₀
Since (D _o-1 )=0, the current control value D ₁ is set as D ₁ =T ₁ −N ₁ according to the first equation, and the deviation H ₁ (=T ₁ −
A control signal a(D ₁ ) corresponding to N ₁ ) is output.

Then, it is assumed that the external load etc. change again by the next control period t ₂ and the target position T ₂ in this period t ₂ becomes T ₁ +ΔT. In this case, the previous controlled amount D ₁ (D _o-1 ) = H ₁ ≠ 0, and the previous controlled amount D ₀ (D _o-2 ) = 0, so according to the second equation, D ₂ = T ₂ - (N ₁ + D ₁ ) = T ₂ - T ₁ = T ₁ + ΔT - T ₁ = ΔT. That is, the control value D ₂ in this case is the control period t ₂
The value corresponds to the newly added change ΔT in the target position. As a result, the total control amount up to this point is D ₁ +D ₂ =T ₁ +ΔT−N ₁ , that is, the deviation between the initial actual position N ₁ and the target position T ₂ =T ₁ +ΔT after changing by two steps. It is assumed to be the amount corresponding to H ₂ . Therefore, the deviation _H2 is eliminated by the control values _D1 and _D2 after the operation delay time L of the pressure-responsive device 13 has elapsed, but before that, the control signal is further applied in the next control cycle _t3 . a(D ₃ ) is output.

However, in the period _t3 , the previous control amount _D2
=ΔT≠0, and the control amount D ₁ before the previous time is = T ₁ −N ₁ ≠0, so the control value D ₃ is calculated according to the third equation, D ₃ =T ₃ −(N ₁ +D ₁ +D ₂ ) = (T ₁ +ΔT)−[N ₁ +(T ₁ −N ₁ )+ΔT] =0. That is, in the control period _t3 , the control value
D ₃ =0, and therefore the actual position will converge to the target position after the delay time L has elapsed.

Furthermore, in the next control cycle t ₄ , since the previous control amount D ₃ = 0, the control amount D ₄ = T ₄ −N ₄ , but at this point the actual position and the target position do not match. Therefore, the control amount D ₄ becomes 0, and the control ends.

As described above, the position of the diaphragm 13b in the pressure responsive device 13 is controlled without over-controlling the target position. When the position of the diaphragm 13b is controlled to match the target position, the opening of the flow control valve 12 or the amount of intake air passing through the bypass passage 11 is adjusted accordingly, and as a result, the engine The rotational speed is converged to the target idle rotational speed corresponding to the operating state.

The above embodiment is an example in which the position of the diaphragm 13b in the pressure response device 13 (the position of the valve body 12a in the flow rate control valve 12) is controlled, but the engine speed is similarly adjusted to the target idle speed. may be directly controlled.

Here, in a general case where the target position or the target idle speed changes in a complicated manner, the control results according to the present invention and the control results according to the conventional method are compared and shown in FIG. In the figure, the solid line indicates the target value,
The broken line shows the control result of the actual position or the actual engine speed according to the present invention, and the dashed line shows the control result of the conventional control. Furthermore, the two-dot chain line shows the control result when the gain is reduced using the conventional method.

According to this figure, the proposed system does not have overshoot like the conventional example shown by the dashed-dotted line, and has better responsiveness to changes in the target value compared to the conventional example shown by the dashed-double line. Prove.

(Effects of the Invention) As described above, according to the present invention, in the idle rotation control that controls the engine rotation speed at idle to converge to the target idle rotation speed set according to the operating condition, the pressure-responsive device is used. Overcontrol due to operation delay is prevented, and stable idle rotation control without overshoot or hunting is realized.

[Brief explanation of the drawing]

Fig. 1 is a time chart showing the conventional problems, Fig. 2 is an overall configuration diagram of the present invention, Fig. 3 is a control system diagram of an embodiment of the present invention, and Figs. 4 and 5 show the operation of the embodiment. Flowchart diagram shown, No. 6, 7, 8
The figure is a time chart showing a specific control example of the embodiment. A19...Engine rotation sensor, B13...Pressure response device, C12...Flow rate control valve, D(16,17)...Pressure control valve, E...Target idle speed setting means, F...
Rotation speed comparison means, G... Control signal output means, 18
...control unit.

Claims (1)

[Claims] 1. An engine rotation sensor that detects the engine rotation speed, a pressure response device that has a pressure chamber and is displaced according to the pressure within the pressure chamber, and is connected to the pressure response device and is displaced to be supplied to the engine. A flow rate control valve that adjusts the amount of intake air; a pressure control valve that receives a control signal and adjusts the pressure in the pressure chamber of the pressure response device; and a pressure control valve that receives an output signal of the engine rotation sensor and controls the actual engine speed indicated by the signal. a rotation speed comparison means for comparing the rotation speed and a separately set target idle rotation speed and outputting a deviation value; and control signal output means for outputting a control signal to the pressure control valve so as to converge, the control signal output means outputting a control signal at predetermined time intervals, and the control signal output means outputs a control signal at a predetermined time interval, When the rotation speed changes, at the first processing point after detecting the change, a control signal with a control value corresponding to the deviation value output from the rotation speed comparison means is output, and at the next processing point, the deviation at that point is output. 1. An engine idle rotation control device, characterized in that the engine idle rotation control device is configured to output a control signal of a control value that is a value that is corrected in a direction in which a change in engine rotation speed decreases.