JPS6198943A - Engine idle rotation control - Google Patents

Abstract

PURPOSE:To facilitate restart of engine under high temperature by performing idle-up control of the idle opening of throttle valve particularly when the cooling water temperature is higher than specific level which is hard to cause start. CONSTITUTION:Under engine operation, ECU59 will first decide whether it is engine start on the basis of on-off condition of starter 55 and if it is prior to engine start, it is decided whether the water temperature detected through a water temperature sensor 47 is higher than specific level which is hard to cause starting. If the answer is YES, the idle opening at engine start is set to the opening for high temperature starting determined with correspondence to proper starting air/fuel ratio. While upon decision of engine start, it is decided whether the cooling water temperature is higher than specific level which is hard to maintain stable rotation of engine and upon decision of YES, feedback control of idle rotation is executed under the condition where it is set to high temperature idle opening determined with correspondence to stable rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for starting an engine, especially at high temperatures, and controlling the idle speed after starting, using a chokeless carburetor that does not include a choke valve.

(Prior Art) Conventionally, as described in Japanese Patent Application Laid-Open No. 56-9630, in an engine equipped with a choke valve, the idle speed is adjusted to an appropriate level after the air-fuel ratio becomes excessively rich due to percolation, etc. In order to increase the engine speed, facilitate restarting at high temperatures, and stabilize idle rotation, the carburetor is equipped with a high temperature compensator for increasing intake air and a dashpot device for increasing idle. The disadvantage was that it required the use of two devices.

(Problems to be Solved by the Invention) The present invention uses a chokeless carburetor to control the idle opening of the throttle valve during BjFJ to idle up using an electric actuator to facilitate restarting the engine when the engine is running high. In addition, the purpose is to smoothly control the idle speed after starting to prevent rough idling and engine stalling immediately after starting.

(Means for Solving the Problems) As shown in FIG. 1, the present invention provides a carburetor equipped with a throttle valve in the intake passage that controls the idle opening degree using an electric actuator. Step 502 is performed before starting the engine.
In step 803, it is determined whether or not the engine cooling water temperature is higher than a specific water temperature at which starting is difficult, and if the engine cooling water temperature is higher than the specific water temperature that is difficult to start, the idle opening at the time of engine starting is set to the appropriate opening at starting. The opening is set to a predetermined high-temperature starting opening corresponding to the fuel ratio, and when the water temperature is below the specific water temperature, the idle opening when starting the engine is set to the normal starting opening in step 304, and step S0
In the state in which starting the engine is determined in step 1, it is determined in step SO5 whether or not the engine cold water temperature is higher than a specific water temperature at which it is difficult to maintain a stable engine rotation speed. Sometimes lJ step S
In 06, the idle opening degree after starting the engine is set to a predetermined high temperature idle opening degree corresponding to maintaining a stable engine rotational speed. Feedback control is performed to the target idle rotation speed, and step SO5
When the engine cooling water temperature is below a certain high temperature water temperature that makes it difficult to maintain a stable engine speed, step SO7 is performed.
There is an engine idle speed control method in which the idle speed of the engine is feedback-controlled to the normal target idle speed while the idle speed is returned to the normal idle speed after the engine is started.

(Embodiment) Next, the configuration of an embodiment of the present invention will be described with reference to FIGS. 2 to 5.

Suits 1 to 4, which respond to the amount of depression of the accelerator pedal, are attached to the intake passage 3 that supplies fuel from the carburetor 2 to the engine, and are biased in the valve closing direction by springs (not shown). The valve closing position of the valve 4 is controlled by the actuator 7, in which the operating lever 6 fixed to the shaft 5 of the throttle valve 4 rotates the threaded rod 10 in the forward and reverse directions via the C motor 8 and gear A7 row 9. This is determined by contact with the touch head 12 at the tip of the actuator tuff that moves the output shaft 11, which is fitted with screws and screws in the circumferential direction, to move back and forth, and the contact of the operating lever 6 with the touch head 12. With this contact, the output shaft 11 resists the biasing force of the spring 13.
The end of the stroke of the output shaft 11 is detected by turning on the idle switch 15 when the final gear 1714 moves back slightly.
6 is detected by contacting the lever 18 of the limit switch 17.

This carburetor 2 is supplied with fuel to a main nozzle 20 formed in a small bench lily 19 of the intake passage 3.
A main cut solenoid valve 22 for cutting at the 1F 821 position, a slow cut solenoid valve 24 for cutting the fuel supply to the slow boat 23 formed near the throttle valve 4 in the intake passage 3, and a main and slow system. An air bleed control valve 25 for adjusting bleed air for the bleed air, in this case, a nut rest 27 is rotated forward and backward via a stepper motor 26 to move the needle valve 29 back and forth together with a threaded rod 28 whose movement in the circumferential direction is restricted. An air bleed control valve 25 adjusts the amount of bleed air supplied from the air hole 30 through each air passage 31.32 to the main system and slow fuel passage 33.34 by moving the air bleed control valve 25 during engine startup and acceleration. etc. a5
Auxiliary fuel pump 35 increases the amount of fuel supplied to the engine, in this case turning on and off the solenoid coil 36.
Due to the t1 return movement of the three pistons via the plunger 38 due to the A action and the biasing force of the spring 37, the fuel from the flow h'I A O of the carburetor 2 is passed through the intake side check valve 41 and once into the cylinder chamber. 42 and an auxiliary fuel pump 35 that supplies the fuel from the discharge side check valve 43 to the intake passage 3 through an auxiliary nozzle 45 formed above the large venturi 44.

In the carburetor 2 configured in this way, the DC motor 8 of the actuator 7, each switch 15.17, each fuel cut solenoid valve 22.24, the stepper motor 26 of the air bleed control valve 25, and the auxiliary fuel A solenoid coil 36 of the pump 35, a throttle opening sensor 46 that is attached to the carburetor 2 and generates an output corresponding to the opening of the throttle valve 4, a water temperature sensor 47 that is attached to the water Vket of the engine, and an ignition sensor. An engine rotation speed sensor 48 such as a coil, a vehicle speed sensor 49 that generates an output corresponding to the speed of the vehicle,
The 02 sensor 50 is installed in the exhaust passage and generates an output corresponding to the oxygen concentration, the clutch/neutral detection sensor 51 changes the output when the clutch is off and in the neutral state, and the side lamp generates an output when the side lamp is on. A switch 52, an economy/diagram lamp 53 that lights up during economy and guiage, an air conditioner switch 54, a starter switch 55, an ignition key switch 56, and an alternator control circuit 5.
7 are connected to an electric control circuit 59 for engine control, commonly known as an ECU, in which power supply from a battery 58 is controlled on and off by an ignition key switch 56.

Next, FIG. 3 is a shell example of the electric control circuit 59, in which the microcomputer CPU, which is controlled according to the program in the storage circuit ROM, receives the engine speed from the engine speed sensor 48 via the waveform shaper 60. In addition to inputting a pulse signal with a corresponding frequency, an analog signal corresponding to the engine cooling water temperature from the water temperature sensor 47 and an analog signal corresponding to the opening degree of the throttle valve 4 from the thrower 1 to opening degree sensor 46 are input. and an analog signal corresponding to the oxygen concentration from the 02 sensor 50 are converted into digital signals via the A/D converter 61 and input via the input port 2, and the idle switch 1
5, clutch/neutral detection switch 51, air conditioner switch 54, pulse output vehicle speed sensor 49, ignition key switch 56, starter switch 55, and side lamp switch 52. On/off signals are input via input port 3. In addition, the output port 4 of the microcomputer CPU is connected to the DC motor 8 of the actuator 7, the solenoid coil 36 of the auxiliary fuel pump 35, the main cut solenoid valve 22, and the slow cutter 1 to solenoid valves through respective drive circuits 65 to 69. 24 and an alternator control circuit 57, and the stepper motor 26 of the air bleed control valve 25 is also connected to the output port door 0 via a drive circuit 71.

Next, the operation of this embodiment will be explained.

In the engine control device configured in this way, in particular the engine of the electronically controlled chokeless carburetor, the microcontroller CρU is controlled according to the engine cooling water temperature. A changing target idol 1ii
1 degree and the target idle rotation speed are set, and in this state, the idle opening degree of the throttle valve 4 and the idle rotation speed of the engine are controlled according to the flow chart shown in FIG.

That is, in step 101, it is determined whether it is 8 o'clock or not based on the on/delta-off state of the starter 55, and if it is before the start of WiJ, the engine cold water temperature is measured in step 102 (3ΦJJ is difficult to identify high temperature). Determine whether the water temperature is above 100°C, for example, and determine whether the engine cooling water temperature is 12 (100°, which is difficult to
C or above, in step 103, the idle opening at the time of engine starting is set to a predetermined high-temperature start l1 corresponding to the appropriate air-fuel ratio at the time of starting, as shown in FIG. 5 or FIG.
i1 degree, and when it is determined in step 102 that the engine cooling water temperature is 100'C or less, step 10 is set.
4 sets the idle opening at engine start to normal 9F; +
In state B, in which the opening degree is set to J+, and engine starting is determined in step 101, in step 105, it is determined that the water temperature of the engine is too low to maintain a stable rotational speed of the engine 41
It is determined whether the specific water temperature is high, for example, 100'C or higher, and if the temperature is 100'C or higher, which makes it difficult to maintain a stable engine speed, in step 106, the idle opening degree after starting the engine is adjusted as shown in Fig. 7 or 8. As shown in the figure, the idle opening is set to a predetermined high-temperature idle opening in order to maintain a stable engine speed. - At the same time, in step 107, the engine idle speed is feedback-controlled to a high temperature target idle speed that can maintain a stable engine speed, and in step 105, the engine cooling water temperature is set to 100 degrees Celsius, which makes it difficult to maintain a stable engine speed. In the following cases, in step 108, the idle opening degree after the engine is started is returned to the normal idle opening degree as shown in FIG. As a result, the engine idle speed is controlled as shown in Fig. 9, and the engine idle speed is controlled as shown in Fig. 9. The engine is controlled to start at a set high temperature and the idle opening after starting is controlled to a target idle 1 which is set in accordance with the engine cooling water temperature, so that the engine can be started easily even at high temperatures. At the same time, it is possible to achieve stable idle speed characteristics with no rough idle or engine stall after starting.

(Effects of the Invention) In a chokeless carburetor, the present invention uses an electric actuator to increase the idle opening of the thrower valves 1 to 1 at high temperatures, especially when the engine cooling water temperature is above a specific water temperature (for example, 100°C) at which starting is difficult. By controlling the engine, it is possible to easily restart the engine at a high temperature, and also to smoothly control the idle speed after starting, thereby preventing rough idling and engine stalling immediately after starting.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the method of the invention.
Fig. 2 is an explanatory diagram of an example of an actual droplet of the present invention, Fig. 3 is an electric circuit diagram thereof, Fig. 4 is a flowchart thereof, and Figs. 5 to 9.
The figure shows its operating characteristics.

Claims (1)

[Claims] In a carburetor equipped with a throttle valve in the intake passage that controls the idle opening with an electric actuator, when the engine cooling water temperature exceeds a certain water temperature that makes starting difficult, the idle opening at engine startup is adjusted to correspond to the optimum air-fuel ratio for starting. When the engine cooling water temperature is higher than a specific water temperature at a high temperature that makes it difficult to maintain a stable engine speed, the idle opening after engine startup is set to a predetermined starting opening at high temperatures. While the engine idle speed is set to a predetermined high-temperature idle opening degree corresponding to the maintenance, the engine idle speed is feedback-controlled to a high-temperature target idle speed that can maintain a stable engine speed, and the engine cooling water temperature is When the temperature of the high-temperature water drops below a specific water temperature at which it is difficult to maintain a stable engine rotation speed, the idle rotation speed of the engine is feedback-controlled to the normal target idle rotation speed while the idle opening degree is returned to the normal idle opening degree. An engine idle speed control method characterized by: