JPS592792B2 - Method for controlling the amount of exhaust gas recirculation for internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas recirculation system (hereinafter referred to as EGR) for an internal combustion engine.
The present invention relates to a method for controlling the amount of exhaust gas recirculation (EGR amount) in a device.

The EGR device extracts part of the exhaust gas from the exhaust system,
This is a device that reduces NOx in exhaust gas by recirculating it to the engine intake system under appropriate control of temperature, timing, flow rate, etc.

Controlling the EGR amount to an optimal value according to engine load conditions is extremely effective in terms of exhaust gas countermeasures.
The present invention aims to achieve the above object by controlling the opening degree of a control valve (EGR valve) according to the intake air amount of the engine, the engine speed, the temperature inside the intake pipe, etc.

Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 1 schematically shows an EGR device for an internal combustion engine and its control system. An EGR pipe 4 is provided between an exhaust pipe 2 and an intake pipe 3 of an engine 1. A portion is returned to the intake pipe 3.

The amount of EGR is controlled by changing the passage cross-sectional area of an EGR valve 50 provided in the pipe 4, and this valve 5 is driven by an actuator 6.

An intake air amount sensor 8 is provided on the upstream side of the EGR port 7 of the intake pipe 3, and a temperature sensor 10 and a pressure measurement port 12 are provided on the downstream side of the port 7 and the throttle valve 9, respectively.
A pressure sensor 11 is attached to this port 12.

Further, a rotation speed sensor 13 is attached to the engine 1.

The sensor 8 measures the intake air amount G, the sensor 10 measures the temperature TB in the intake pipe 3, the sensor 11 measures the absolute sensor PB downstream of the throttle valve in the intake pipe 3, and the sensor 3 measures the rotational speed N of the engine 1. input to the control device 14;

A memory device 15 is separately connected to the control device 14.

The E G Rr amount control method of the present invention drives the actuator 6 using the above 04 types of information, namely Ca, TB and N, and determines the optimum valve opening degree. Please refer to Figures 2 and 3 regarding 1. I will explain.

(1) First, the optimum EGR rate xrci't is written in advance in the memory device ROMI 5 by arbitrarily combining the intake air amount G and the engine speed N.

The value of Xl”ef, can be determined by experiment, −
1 Here, EGR, rate is G (71:E
The amount of GR, G-7G, is the total amount of waste sucked into the engine, and a
e Yes.

(2) Next, the absolute pressure PB1 downstream of the throttle valve 9 of the intake pipe 3 and the gas temperature TB in the intake pipe 3 are measured at the engine speed N1 when the engine is actually operated.

As shown in Fig. 3, the engine speed N is equal to the crank angle 1
° is detected as the number of pulses at
7, input it to the interface circuit 21 and store it in the R and AM 22.

The intake pipe absolute pressure (negative pressure) PB and the gas temperature TB are detected as analog quantities and are manually input to the interface circuit 21 via the AD converter 23, and stored in the RAM 22 as the same value.

From these values, the engine-specific function G 1G 2f
(N, PB, TB) a e Total engine intake test t (G + G) value
Calculate e.

(3) Next, measure the intake air amount G when the engine is actually operated in the same manner.

Intake air amount G. is determined by an intake air amount sensor, for example, an air flow meter 8, and the analog amount is determined by an A-D converter 23.
input to the interface circuit 21 via the RAM 22
to be memorized.

Next, the actual EGR rate xreal is determined using the calculated total engine intake gas amount (Ga + Go) and the actually measured intake air amount F by the following equation.

(4) Actual EGR rate xrcal obtained in this way
and the optimum EGR rate xref stored in the memory device ROMI 5, and the results are sent through the interface circuit 21.

■Output as a signal.

(5) While repeating the calculations and comparisons as in (2) to (4) above, the EGR valve 5 is feedback-controlled so that xreal matches xref.

Next, the actuator (
The drive method of the pulse motor) 6 will be explained.

As shown in the table below, (1) xreaL>xref, then■
= L, shifts the clock pulse in response to the e-n signal]・
The signal is sent to the register 25 and the pulse motor 6 is rotated in the valve closing direction.

(2) If xreal<xref, the clock pulse is sent to the shift register 25 upon receiving the signal -H1 -H, and the pulse motor 6 is rotated inward to open the valve.

(3) xreal=xref, then ■−ri, /'f(
, (Ei==== Upon receiving the L signal, stop sending the I cock pulse to the shift register 25 and start the pulse motor 6.
to stop.

(4) Fully open and fully open detection switch 27 for EGR valve 5
If the EGR and valve 5 reach the fully open or fully closed position, the fully open/closed processing logic 28 will cause ■,■
Even if the signal is in (1) or (2) above, the rotation of the pulse motor 6 is forcibly stopped, and the pulse motor 6 is made to rotate again when the next reverse signal comes.

Next, a method of comparing xreal and xref will be explained.

In addition to simply comparing the sizes of xreal and xref, it is also possible to use any of the following methods.

(1) xreal>, xref, and 1xrea
l-xref, if I>K and xfeal xref.

The EGR valve is opened and closed only when and I xreal-xref, l>K, and is stopped at other times.

That is. It opens and closes only when the deviation is greater than or equal to .

Here, K is an appropriate constant. (2) l xre
The clock frequency is controlled by the (2) signal according to the values of al-xref and l.

As described above, in the present invention, intake air amount G, engine speed N1, absolute pressure PB in the intake pipe, and temperature T in the intake pipe
By actually measuring B, the EGR amount can be controlled so as to approach the optimum EGR rate.

Note that the actuator 6 is not limited to the Hals motor as in the above embodiment, but may also be a servo motor, a vacuum servo, or the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an EGR device for an internal combustion engine and its control system, and FIGS. 2 and 3 are diagrams illustrating an EGR amount control calculation procedure and an actuator driving method according to the present invention. 1...engine, 2...exhaust pipe, 3...intake pipe,
4...EGR bifu, 5...EGR valve, 6...
・Actuator, 8...Intake air amount sensor, 10・
...Intake pipe temperature sensor, 11...Intake pipe pressure sensor,
13... Rotation speed sensor, 14... Control device, 15 Memory device.

Claims (1)

[Claims] 1. Taking out a part of the exhaust gas of an internal combustion engine from the exhaust system,
In an exhaust gas recirculation device in which exhaust gas is returned to the intake system via a control valve, (a) the optimum EGR rate (xref,) determined by experiment for any combination of G and N is stored in advance in the mesori device; (b) N and P B when the engine is actually operated
Measure tTB and use the engine-specific function G - f (N, PB, TB) to calculate a
e Calculate the total engine intake gas amount (G + G), and (
c) Similarly, measure G when the engine is actually operated, and use G + G obtained in (b) above to calculate the current a
e Calculate the actual EGR rate (xreal) from (d) N and G measured in (b) and (c) above.
The optimum EGR rate (xr
(e) compare the xreal and xref and output the result; (f) repeat the operations (b) to (e);
A method for controlling the amount of exhaust gas recirculation, characterized in that the valve is feedback-controlled so that the xreal and xref match. However, G is the amount of intake air, Ge is the amount of exhaust gas recirculation, N is the engine speed, PB is the absolute pressure downstream of the throttle valve in the intake pipe, and TB is the temperature in the intake pipe and EGR.
Let the rate (X) = G. Ga+Ge