JPH0630465U - Exhaust gas recirculation controller for direct injection alcohol engine - Google Patents

Abstract

(57) [Summary] [Purpose] The objective is to improve the startability of a direct injection alcohol engine. [Structure] In step 1, the presence or absence of a cranking signal input from the engine key switch is detected. If a cranking signal is input, the process proceeds to step 2, and if not, the process proceeds to step 3. In step 2, a signal for fully closing the exhaust gas recirculation control valve is output to the actuator to operate the actuator, and in step 3, a signal for normally controlling the exhaust gas recirculation control valve based on the engine speed and the load is supplied to the actuator. To operate the actuator.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an exhaust gas recirculation control device for a direct injection alcohol engine, and more particularly to a technique for improving startability.

[0002]

[Prior art]

 A direct-injection alcohol engine is known in which an alcohol fuel such as methanol is directly injected into a combustion chamber. Such a direct-injection alcohol engine has a problem that the combustibility at a low load is poor and unburned gas such as unburned methanol and CO are discharged.

Therefore, it is known that the application of an exhaust gas recirculation control device that recirculates a part of exhaust gas into intake air is effective (see Japanese Utility Model Application Laid-Open No. 2-76137 and Japanese Application No. 3-76497). ).

[0004]

[Problems to be solved by the device]

 However, in a conventional direct-injection alcohol engine with such an exhaust gas recirculation control device, the exhaust gas is recirculated to the intake air even during engine start cranking. There was a problem that startability deteriorated. This has been clarified by the experiments conducted by the inventors of the present invention. If exhaust gas recirculation is performed at the engine start, the oxygen concentration in intake air decreases, and if the exhaust gas recirculation rate exceeds a certain value, the engine will not start.

FIG. 4 is a diagram showing the relationship between the exhaust gas recirculation rate and engine startability, and the relationship between the intake oxygen concentration. The higher the exhaust gas recirculation rate, the longer the starting time and the more the engine cannot start. Is clear. Therefore, the present invention has been made in view of the above, and an object of the present invention is to improve the controllability of the exhaust gas recirculation control valve to improve the startability of a direct injection alcohol engine.

[0006]

[Means for Solving the Problems]

 The present invention, as shown in FIG. 1, detects an engine start in an exhaust gas recirculation control device equipped with an exhaust gas recirculation control valve that is installed in an exhaust gas recirculation passage of a direct injection alcohol engine and controls an exhaust gas recirculation amount. A start detection means and a control means for controlling the exhaust recirculation control valve to be fully closed when the start is detected by the start detection means.

[0007]

[Action]

 Normally, the oxygen concentration in the intake air is high when the engine is started, but if the exhaust gas recirculation is performed at this time, the oxygen concentration will decrease and poor startability will occur. Therefore, when the engine start is detected, the exhaust gas recirculation control valve is fully closed to prevent exhaust gas recirculation, whereby the startability failure can be eliminated.

[0008]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 2, a combustion chamber 5 formed by a cylinder head 2 of a direct injection alcohol engine 1 and a cavity 4 provided in a piston 3 is filled with alcohol fuel from a fuel injection nozzle 6 attached to the cylinder head 2. Directly injected. The spray alcohol fuel is ignited by the spark plug 7.

An intake throttle valve 9 is arranged in the intake pipe 8, and an exhaust gas recirculation pipe 11 branched from an exhaust pipe 10 is connected downstream of the intake throttle valve 9. An exhaust gas recirculation control valve 12 for controlling the exhaust gas recirculation is interposed in the exhaust gas recirculation pipe 11. The exhaust gas recirculation control valve 12 is controlled to open / close by an actuator 13. A control signal from the control unit 14 is input to the actuator 13, and the actuator 13 is controlled based on the control signal. That is, the control unit 14 receives the rotation speed signal output from the engine rotation speed sensor 15 and the load signal output from the load sensor 16, and serves as a start detection means for detecting the start of the engine 1. Cranking signals from the engine key switch 17 are input, the actuator 13 is controlled based on these input signals, and the exhaust gas recirculation control valve 12 is controlled.

The control unit 14 has a software function as a control means for fully closing the exhaust gas recirculation control valve 12 when the start of the engine 1 is detected by the input of the cranking signal from the engine key switch 17. Equipped. FIG. 3 is a flowchart showing the above control contents. In step 1, the presence or absence of a cranking signal input from the engine key switch 17 is detected. If a cranking signal is input, the process proceeds to step 2 and the input is performed. If not, proceed to step 3. In step 2, a signal for fully closing the exhaust gas recirculation control valve 12 is output to the actuator 13 to operate the actuator 13, and in step 3, the exhaust gas recirculation control valve 12 is normally operated based on the engine speed and the load. A control signal is output to the actuator 13 to operate the actuator 13.

According to this structure, when the engine 1 is normally started, the oxygen concentration in the intake air is high, and there is no problem in starting performance. However, if exhaust gas recirculation is performed at this time, the oxygen concentration will drop, and poor startability will occur. As described above, when the start of the engine 1 is detected, the exhaust gas recirculation control valve is fully closed to stop the exhaust gas recirculation, and as a result, poor startability can be eliminated.

Although the present invention has been described with reference to the specific embodiments as described above, the present invention is not limited to this, and those skilled in the art can apply the present invention to the present invention. It should be noted that various changes and modifications can be made without departing from the scope of the attached utility model registration request.

[0013]

[Effect of device]

 As described above, in the present invention, in a direct-injection alcohol engine, when exhaust gas recirculation control valve is fully closed when engine start is detected, exhaust gas recirculation is not performed, so that poor startability can be eliminated. The practical effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram of an exhaust gas recirculation control device for a direct injection alcohol engine according to the present invention.

FIG. 2 is a system diagram showing an embodiment of an exhaust gas recirculation control device for a direct injection alcohol engine according to the present invention.

FIG. 3 is a flowchart showing the control contents of the above embodiment.

FIG. 4 is a characteristic diagram showing a relationship between an exhaust gas recirculation rate and engine startability and a relationship between intake oxygen concentration.

[Explanation of symbols]

 1 Direct injection alcohol engine 11 Exhaust gas recirculation pipe 12 Exhaust gas recirculation control valve 13 Actuator 14 Control unit 17 Engine key switch

Claims (1)

[Scope of utility model registration request] 1. An exhaust gas recirculation control device comprising an exhaust gas recirculation control valve for controlling an exhaust gas recirculation amount, which is interposed in an exhaust gas recirculation passage of a direct injection alcohol engine, and start detection means for detecting engine start, and the start. An exhaust gas recirculation control device for a direct injection alcohol engine, comprising: a control device for fully closing the exhaust gas recirculation control valve when a start-up is detected by the detection device.