JPS60122259A - Exhaust recycling quantity controlling device for diesel engine - Google Patents

Abstract

PURPOSE:To control the flow rate of EGR always accurately by feedback controlling said flow rate of EGR in accordance with the rate of excess of air obtained based on the density of O2 from an O2 sensor of an exhaust passage. CONSTITUTION:While an engine is operated, when judgment is made that it is in a condition to carry out EGR through a control means 9 in accordance with each detecting signal thetaL, Ne, TW of a lever opening sensor 3 attached to a fuel injection pump 16, an engine speed sensor 4, and a cooling water temperature sensor 5, first, a target rate of excess of air lambdat is read out of a map based on the detected signals thetaL, Ne. Then, an actual rate of excess of air lambdaa is operated based on an O2 density detecting signal SO from a lean sensor 1. And, judgment is made whether the difference DELTAlambda between both rates of excess of air is within an allowable error epsilon or not and, if it is not, each driving time for a solenoid valve 6 and a negative pressure regulating valve 7 is controlled in accordance with the difference DELTAlambda, to adjust the opening of an EGR valve 13.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling the amount of exhaust gas recirculation in a diesel engine.

BACKGROUND ART Conventionally, as part of efforts to reduce pollution from diesel engines, so-called clean engines equipped with exhaust gas recirculation (EGR) systems that reduce NOx in exhaust gas have been actively developed.

Also, in the EGR system of diesel engines, especially non-turbo diesel engines, the amount of exhaust gas recirculation (EGR
In order to control the amount of recirculation (EGR), an exhaust gas recirculation flow control valve (EGR
A GR valve) is provided, and the amount of EGR is controlled by controlling the opening and closing of this valve as appropriate.

That is, depending on the engine speed Ne from the engine speed sensor and the lever opening degree θL of the fuel injection pump, E
Standard lift amount L of the GR valve (exhaust gas recirculation amount adjustment valve).

is selected, and the lift amount L0 is corrected according to the cooling water temperature, atmospheric pressure, boost pressure, and back pressure to determine the final target lift amount L1.

This target lift Lt is compared with the actual lift amount La, and feedback of the opening/closing driving state (driving time) of the EGR valve is performed according to the driving logic of the EGR valve.

However, in this type of conventional EGR system, E
There is a problem that the amount of GR cannot be accurately controlled.

Furthermore, with such conventional control devices, the amount of EGR cannot be directly fed back, so even if various corrections are made,
There is a problem that control accuracy is low, and various correction sensors are required, resulting in high cost.

The present invention aims to solve these problems.
An object of the present invention is to provide an exhaust gas recirculation amount control device for a diesel engine that has a simple configuration and can accurately control the amount of ECR.

Therefore, the exhaust gas recirculation amount control device for a diesel engine according to the present invention is capable of adjusting the exhaust gas recirculation passage interposed between the intake passage and the exhaust passage and the exhaust gas recirculation amount of the exhaust gas recirculation passage. In a diesel engine equipped with an exhaust gas recirculation amount regulating valve and a control means for controlling opening and closing of the exhaust gas recirculation amount regulating valve, an engine state sensor detecting the operating state of the engine and detecting the amount of oxygen in the exhaust passage are provided. The control means includes a target excess air ratio calculation unit that receives a detection signal from the engine condition sensor and calculates a target excess air ratio, and a target excess air ratio calculation unit that receives the detection signal from the O2 sensor. A feedback control signal is sent to the exhaust gas recirculation amount adjusting valve according to each output signal from the actual excess air ratio calculation section that calculates the actual excess air ratio using the above-mentioned target excess air ratio calculation section and the actual excess air ratio calculation section. It is characterized by being equipped with an exhaust gas recirculation amount adjustment valve control section that outputs the amount of air.

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
1 to 3 show an exhaust gas recirculation amount control device for a diesel engine as an embodiment of the present invention.
2 is a block diagram showing its control means, and FIG. 3 is a flowchart showing its control procedure.

As shown in FIG. 1, an EGR passage (exhaust gas recirculation passage) 12 is interposed between an intake passage 10 and an exhaust passage 11 on a non-turbo diesel engine.
The passage 12 is provided with a pressure-responsive EGR valve (exhaust gas recirculation amount adjustment valve) 13 that controls the EGR amount (exhaust gas recirculation amount).

The pressure response device 2 for the EGR valve 13 has a working chamber 2b partitioned off by a diaphragm 2a, and a control passage 14 is connected to the working chamber 2b.

Note that the EGR valve 1 is located in the working chamber 2b of the pressure-responsive device 2.
3 is loaded with a spring 2c that biases it in the closing direction.

When negative pressure acts within the working chamber 2b of the pressure response device 2, the EGR valve 13 is lifted against the spring 2c.
When the EGR valve 13 is operated in the opening direction and atmospheric pressure acts within the working chamber 2b, the EGR valve 13 becomes fully closed.

Incidentally, a negative pressure regulating valve (VAC side solenoid valve) 7 is connected to the control passage 14 through an orifice 15a. This negative pressure regulating valve 7 has an input side connected to a vacuum pump 8 and an output side connected to a control passage 14, and is a valve that generates an operating negative pressure according to a control signal from a control means 9. It is.

As a result, an operating negative pressure is supplied to the control passage 14 according to the engine load.

In addition, a solenoid valve (VENT side solenoid valve) 6 is connected to the output side of the negative pressure regulating valve 7 through an orifice 15b.
is provided, and this solenoid valve 6 and negative pressure regulating valve 7
According to the control signals Ca and Cb from the control means 9,
Adjusted negative pressure from the negative pressure regulating valve 7 or atmospheric pressure through the solenoid valve 6 can be selectively supplied to the control passage 14 .

Further, the exhaust passage 11 is provided with a lean sensor 1 as an O2 (oxygen) sensor.
For example, a tilted O2 sensor is used, and this lean sensor 1 has a tilted output characteristic on the leaner side than the stoichiometric air-fuel ratio of the air-fuel mixture supplied to the engine E, and the O2 concentration detection signal S0 is output to the control means 9.

The fuel injection pump 16 is provided with a lever opening sensor 3 and an engine state sensor 4 as engine state sensors for detecting the engine operating state, and the engine E body is provided with a cooling water temperature sensor 5. Detection signals from these sensors 3 to 5 are sent to control means 9.

As shown in FIG. 2, the control means 9 includes the lever opening θL from the lever opening sensor 3 and the engine state sensor 4
A target excess air ratio calculation section 9b is provided which receives the engine rotational speed Ne from the target excess air ratio calculation section 9b.
b picks up the target excess air ratio λt from these detection signals θL and Ne from a map given in advance,
It is supplied to an EGR valve control section 9d, which serves as an exhaust gas recirculation amount adjustment valve control section.

Further, the control means 9 is provided with an EGR prohibition determination section 9a that receives the lever distance θL, the engine speed Ne, and the coolant temperature Tw from the coolant temperature sensor 5.
The R prohibition determination unit 9a detects these detection signals θL, Ne, and T.
Based on w, it is determined whether or not to perform EGR, and a prohibition determination signal Sg is supplied to the EGR valve control section 9d.

Furthermore, the control means 9 is provided with an actual excess air ratio calculation section 9c that receives the O2 concentration detection signal S0 from the lean sensor 1, and this actual excess air ratio calculation section 9c calculates the combustion The actual excess air rate λa in the room is picked up from a map given in advance, etc., and is supplied to the EGR valve control section 9d.

The EGR valve control unit 9d uses these calculated signals λt, λ
a and the prohibition determination signal Sg, the solenoid valve (V
A drive control signal Ca for the ENT side solenoid valve) 6 and a drive control signal Cb for the negative pressure regulating valve (VAC side solenoid valve) 7 are output.

Since the exhaust gas recirculation amount control device for a diesel engine according to the present invention is constructed as described above, the control means 9 performs arithmetic control as shown in FIG.

First, the pump lever opening degree θL, engine speed Ne, and cooling water temperature Tw are read (steps a1 to
a3) Then, based on these detection signals θL, Ne, and Tw, the EGR prohibition determination unit 9a determines whether or not EGR is prohibited (step a4), and if it is determined that EGR is prohibited, the prohibition determination is made. For a predetermined period of time immediately after, V
Open the ENT side solenoid valve 6, and from then on,
The driving time Tva is set so that the ENT side solenoid valve 6 and the VAC side solenoid valve 7 are respectively closed.
c and Tvent are adjusted, whereby the pressure in the working chamber 2b of the pressure response device 2 rises to atmospheric pressure, the EGR valve 13 is closed, and the process starts again from step a1.

When it is determined that EGR is to be performed, the detection signal θL
, Ne, the target excess air ratio calculation unit 9b reads the target excess air ratio λt from the map (step a5), then reads the O2 concentration detection signal S0 from the lean sensor 1 (step a6), and calculates the actual excess air ratio. The calculation unit 9c converts it into the actual excess air ratio λa in the combustion chamber (step a7)
.

Then, the EGR valve control unit 9d determines whether the absolute value of the difference between these excess air ratios λa and λt is within the tolerance ε (step a8), and if it is within the tolerance ε, the current Solenoid valve 6 and negative pressure regulating valve 7
Maintain the opening/closing driving state (driving time) of , and repeat step a.
Processing starts from 1.

If it is outside the tolerance ε, the driving time Tvent of the solenoid valve 6 and the driving time T of the negative pressure regulating valve 7 are determined according to the difference (λa - λt) between the actual excess air ratio λa and the target excess air ratio λL.
vac is calculated (step a9), and the solenoid valve 6 and negative pressure regulating valve 7 are driven so that these drive times Tvent and Tvac are achieved (step a9).
10).

As a result, the pressure inside the working chamber 2b is regulated to the set pressure through the control passage 14, the opening degree of the EGR valve 13 is adjusted, and a desired amount of exhaust gas is supplied to the intake passage 10.

As described in detail above, according to the exhaust gas recirculation amount control device for a diesel engine of the present invention, the exhaust gas recirculation passage interposed between the intake passage and the exhaust passage, and the exhaust recirculation passage in the exhaust gas recirculation passage are provided. In a diesel engine equipped with an exhaust gas recirculation amount adjustment valve that can adjust the amount of circulation, and a control means that controls opening and closing of the exhaust gas recirculation amount adjustment valve, an engine state sensor that detects the operating state of the engine; An O2 sensor that detects the amount of oxygen in the exhaust passage is provided, and the control means includes a target excess air ratio calculating section that receives a detection signal from the engine condition sensor and calculates a target excess air ratio, and the O2 sensor. The actual excess air ratio calculation unit calculates the actual excess air ratio in response to the detection signal from With a simple structure including an exhaust gas recirculation amount adjustment valve control section that outputs a feedback control signal to the adjustment valve, the following effects and advantages can be obtained.

(1) Since the amount of exhaust gas recirculated to the intake passage is feedback-controlled according to the excess air ratio (=EGR amount) derived based on the O2 concentration from the O2 sensor in the exhaust passage, accurate EGR amount can be determined. can be controlled.

(2) The sensor for correcting the amount of exhaust gas recirculation used in the conventional control device becomes unstable, thereby reducing costs and improving reliability by reducing trouble sources.

[Brief explanation of the drawing]

The figures show an exhaust gas recirculation amount control device for a diesel engine as an embodiment of the present invention, in which Fig. 1 is an overall configuration diagram thereof, Fig. 2 is a block diagram showing its control means,
FIG. 3 is a flowchart showing the control capacity. 1. Lean sensor as an O2 (oxygen) sensor, 2.
- Pressure response device, 2a...Diaphragm, 2b...Working chamber, 2c...Spring, 3...Lever opening sensor as engine condition sensor, 4...Engine speed sensor as engine condition sensor, 5... Cooling water temperature sensor as an engine condition sensor, 6... Solenoid valve (VENT side solenoid valve), 7... Negative pressure adjustment valve (VAC side solenoid valve), 8... Vacuum pump, 9... Control means, 9a... EGR prohibition determination section, 9b..Target excess air ratio calculation section, 9c..Actual excess air ratio calculation section, 9d..EGR valve control section as an exhaust gas recirculation amount adjustment valve control section;
10...Intake passage, 11...Exhaust passage, 12...Exhaust gas recirculation passage (EGR passage), 13...Exhaust gas recirculation amount adjustment valve (EGR valve), 14...Control passage, 15a, 15b...
Orifice, 16... Fuel injection pump, E... Engine representative Patent attorney Yoshihiko Iinuma Figure 2 19 Figure 3) Correction, 1F, (Method゛) Akashi 1b5] A), March 5E1 1. 5□1゛1 Agency L<'! 'i' Kazuo Wakasugi 1.1.1
0.1 kae 27, porridge. 1933 and 1939 Toku 3' ()ori No. 229727-2
Name of the invention (1, i ~ ゛ Easel engine Senki Re (j15 ring year, control device: (Y + ti :il-↓- name ゛1 I'l which relationship Application!,. jl1 Oral history number 1() 吋) 1i:+)i 東しi(東口lii6石石r'El'
A No. 3 No. 8 Name 1jI, (623) ■Tamabishi Automatic Oki-)
To Nigyo Co., Ltd. 71 agent! lii;I history number 1 f:i (,)11(suj
East 5; (Miyakokai I-Yado 1me, Minamimotomachi 5-3-5 supplementary order [1-11 1975 2 RL 8F! (Shipping 1-1 1981 2JJ28F+) Ming A:l
Full text of book ll. ? Among the amendments, 1" G Specification - Obituary with 9 degrees Celsius and the letters 1 - Ruta 2. ノ) amended as shown in the attached sheet)" 1, 'C) Attachment 1''') Category j 1-1 Uchikinbun amendment 41
tl'r! : ] trace

Claims (1)

[Claims] An exhaust gas recirculation passage interposed between the intake passage and the exhaust passage, an exhaust gas recirculation amount adjustment valve that can adjust the amount of exhaust recirculation in the exhaust recirculation passage, and opening/closing of the exhaust gas recirculation amount adjustment valve. In a diesel engine equipped with a control means for controlling the engine state, an engine state sensor for detecting the operating state of the engine and an O2 sensor for detecting the amount of oxygen in the exhaust passage are provided, and the control means has a control means for controlling the engine state. a target excess air ratio calculation unit that receives a detection signal from the sensor and calculates a target excess air ratio; an actual excess air ratio calculation unit that receives a detection signal from the O sensor and calculates an actual excess air ratio; and an exhaust gas recirculation amount adjustment valve control section that outputs a feedback control signal to the exhaust gas recirculation amount adjustment valve in accordance with each output signal from the target excess air ratio calculation section and the actual excess air ratio calculation section. An exhaust recirculation amount control device for a diesel engine, characterized by: