JPH0218305Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to an auxiliary fuel discharge detection device for an engine that detects whether auxiliary fuel is reliably discharged into the intake passage by the operation of an auxiliary fuel pump. It is.

(Prior Art) Conventionally, as described in Japanese Patent Application Laid-Open No. 56-107940, when the throttle valve is almost fully closed and fuel suction is insufficient, or when the engine is accelerating, An auxiliary fuel pump is used as an auxiliary fuel supply means for temporarily increasing the amount of fuel.
Engine performance decreases because auxiliary fuel is not discharged, but it is difficult to determine whether this decrease in engine performance is due to a failure of the auxiliary fuel pump or other engine trouble, and during normal operation after warm-up. The problem was that the impact was not that great, and the vehicle continued to be driven with the engine in poor condition for unknown reasons.

As a countermeasure for this, for example, as shown in Figures 2 and 3, the microcomputer of the electric control circuit ECU for engine control is input to the base of the transistor Tr for driving the auxiliary fuel pump SAP, one end of which is connected to the power supply VB. Output P1 from the CPU and
The collector potential P2 of the transistor Tr is compared with the collector potential P2 of the transistor Tr according to the flowchart of FIG. 3 to determine whether the auxiliary fuel pump SAP is abnormal, that is, step SO1.
At step SO2, it is determined whether P1 is "H" or not, and when P1 is "H", it is determined at step SO2 whether P2 is "H" or not. When P2 is "L", the auxiliary fuel pump SAP is
The auxiliary fuel pump was determined to be normal at step SO3 with no disconnection or short circuit, and at step SO1 the auxiliary fuel pump was determined to be normal.
When P2 is determined to be "H" at step SO4 when it is "L", it is determined that the auxiliary fuel pump is normal at step SO3, but P2 is determined to be normal at step SO1.
When P2 is determined to be "H" at step SO2 when it is "H", and when P1 is determined to be "L" at step SO1
When P2 is determined to be "L" at step SO4, it is determined that the circuit is disconnected or short-circuited, and it is determined that the auxiliary fuel pump SAP is abnormal at step SO5.

However, even in this case, the auxiliary fuel pump
Even though there is no abnormality in the electrical operation of the SAP, it is not possible to detect auxiliary fuel discharge failures due to vapor lock due to a rise in fuel temperature, foreign matter getting stuck, nozzle clogging, etc., and the vehicle is driven with the engine malfunctioning. There was a drawback.

(Problems to be Solved by the Invention) The object of the present invention is to detect whether or not auxiliary fuel is reliably discharged into the intake passage by the operation of the auxiliary fuel pump.

(Means for solving the problem) As shown in FIG. 1, the present invention, as shown in FIG. When the auxiliary fuel is discharged into the passage 100, the auxiliary fuel is applied to the auxiliary fuel discharge collision position A of the intake passage 100, where the auxiliary fuel from the auxiliary fuel pump SAP is discharged through the auxiliary nozzle 101, thereby increasing the output. When the auxiliary fuel discharge confirmation sensor 102 that changes the auxiliary fuel discharge confirmation sensor 102 is installed, and when the auxiliary fuel discharge confirmation sensor 102 does not generate an output signal corresponding to the auxiliary fuel discharge when the auxiliary fuel pump SAP is activated, the auxiliary fuel pump
An auxiliary fuel discharge detection device for an engine includes an abnormality determining means 103 for determining an SAP abnormality.

(Embodiment) Next, the configuration of an embodiment of the present invention will be explained with reference to FIGS. 4 to 6.

A throttle valve 4, which opens in response to the amount of depression of the accelerator pedal, is attached to an intake passage 3 that supplies fuel from the carburetor 2 to the engine, and is biased in the valve closing direction by a spring (not shown). The valve closing position of the valve 4 is determined by the throttle lever 6 fixed to the shaft 5 of the throttle valve 4 being actuated by an actuator 7, in this case a reversible DC motor.
A threaded rod 10 whose movement in the circumferential direction is restricted by rotating the threaded rod 10 in forward and reverse directions via a motor 8 and a gear train 9.
This is determined by contact with the touch head 12 at the tip of the actuator 7, which moves the output shaft 11, which is screw-fitted with a screw, back and forth. The end of the stroke of the output shaft 11 is detected by turning on the idle switch 15 when the final gear 14 moves slightly backward together with the output shaft 11.
This is detected when the upper dog 16 comes into contact with the lever 18 of the limit switch 17.

This carburetor 2 includes a main cut solenoid valve 22 for cutting off the fuel supply to the main nozzle 20 formed in the small bench lily 19 of the intake passage 3 at the main jet 21 position, and a main cut solenoid valve 22 formed near the throttle valve 4 of the intake passage 3. slow port 2
3, and an air bleed control valve 25 for adjusting bleed air for the main and slow systems. Needle valve 29 together with threaded rod 28 whose directional movement is restricted
an air control valve 25 that adjusts the amount of bleed air supplied from the air hole 30 to the main system and slow system fuel passages 33, 34 through the air passages 31, 32 by moving back and forth;
An auxiliary fuel pump 35 driven by an electromagnetic solenoid that increases the amount of fuel supplied to the engine during engine startup, acceleration, etc. In this case, the piston is pumped through a plunger 38 by the on/off operation of a solenoid coil 36 and the biasing force of a spring 37. 39, the float chamber 4 of the carburetor 2
0 is once sucked into the cylinder chamber 42 through the suction side check valve 41, and then supplied to the intake passage 3 from the discharge side check valve 43 through the auxiliary nozzle 45 formed above the large bench lily 44. Fuel pump 35 and auxiliary nozzle 45
The fuel discharge confirmation sensor SNS, such as a thermistor, thermocouple, or piezoelectric element, changes the output due to the temperature change or pressure change caused by the application of the auxiliary fuel when the auxiliary fuel is directly hit by the auxiliary fuel discharged from the SNS. each installed.

In the carburetor 2 formed in this way, the DC motor 8 of the actuator 7, each switch 15,
17, each electromagnetic valve 22, 24 for fuel cut, the stepper motor 26 of the air bleed control valve 25, the solenoid coil 36 of the auxiliary fuel pump 35, and the valve that is attached to the carburetor 2 and corresponds to the opening degree of the throttle valve 4. a throttle opening sensor 46 that generates an output, a water temperature sensor 47 attached to the water jacket of the engine, and an engine rotation speed sensor 48 such as an ignition coil.
, a vehicle speed sensor 49 that generates an output corresponding to the speed of the vehicle, and an O ₂ sensor 50 that is attached to the exhaust passage and generates an output that corresponds to the oxygen concentration.
Clutch/neutral detection sensor 5 that changes the output when the clutch is off and in neutral state
1, a side lamp detection sensor 52 that generates an output when the side lamp is on, and an economy/diagnosis lamp 53 that lights up during economy and diagnosis.
, an air conditioner switch 54, a starter switch 55, an ignition key switch 56, an alternator control circuit 57, and a fuel discharge confirmation sensor SNS that changes the output depending on temperature changes or pressure changes caused by application of auxiliary fuel. Each is 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 shows a specific 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 an engine signal from the engine rotation speed sensor 48 via a waveform shaper 60. In addition to inputting a pulse signal with a frequency corresponding to the rotational speed, 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 throttle opening sensor 46 are input. , an analog signal corresponding to the oxygen concentration from the O2 sensor 50, and an analog signal corresponding to the temperature change or pressure change due to application of auxiliary fuel from the fuel discharge confirmation sensor SNS, that is, as shown in FIG. Resistor R from the connection point between discharge confirmation sensor SNS and resistor R1
Each of the analog signals output through the A/D converter 61 is converted into a digital signal and input through the input port 62, and
In addition, the idle switch 15, the clutch/neutral detection switch 51, and the air conditioner switch 54
On/off signals from the pulse output vehicle speed sensor 49, ignition key switch 56, and starter switch 55 are inputted via the input port 63, and the microcomputer
The output port 64 of the CPU has each drive circuit 65 to
69 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 cut solenoid valve 24.
and alternator control circuit 57, as well as an output port 70 and a drive circuit 71.
A stepper motor 26 of the air bleed control valve 25 is connected through the air bleed control valve 25.

Next, the operation of this embodiment will be explained.

In the engine control device configured in this way, in particular the control device for the electronically controlled chokeless carburetor, the microcomputer CPU has the following functions:
A target idle opening degree and a target idle rotation speed are set, which change according to the engine cooling water temperature, and the engine is in a state in which the throttle valve 4 is set to the target idle opening degree during idling operation after warm-up. In addition to controlling the idle speed to reach the target idle rotation speed, the microcomputer CPU also controls the auxiliary fuel when the fuel discharge confirmation sensor SNS is the thermistor SNS, as shown in FIG. 7. The output voltage from the thermistor SNS corresponding to the set temperature ΔTHR is set corresponding to the temperature change amount ΔTHS of the thermistor SNS that changes depending on the previous temperature THS1 and the subsequent temperature THS2, and the output voltage from the thermistor SNS is set corresponding to the set temperature ΔTHR. During the 35 control, the auxiliary fuel pump 35 is driven and controlled while checking for an auxiliary fuel discharge abnormality according to the flowchart shown in FIG.

That is, in step 101, the auxiliary fuel pump 35 is activated when the engine is started or when the engine is accelerated.
It is determined whether the drive request flag is set or not. In the request flag set state, it is determined in step 102 whether or not the auxiliary fuel pump 35 energization flag is set. In the energization flag reset state, the auxiliary fuel pump 35 is energized in step 103. The temperature THS1 of the thermistor SNS before the fuel is discharged is set in the RAM of the microcomputer CPU, and in step 104 an on-time corresponding to the amount of discharged auxiliary fuel is set in the drive counter for the auxiliary fuel pump 35, and in step 105 the auxiliary fuel pump 3
5 is driven, and the auxiliary fuel pump 35 energization flag is set in step 106.

In the next control cycle in which the auxiliary fuel pump 35 is energized, the set state of the auxiliary fuel pump 35 energization flag is determined in step 102, and it is determined in step 107 whether or not the ON time of the auxiliary fuel pump 35 drive counter has elapsed. If it is determined that the auxiliary fuel pump 35 has elapsed, the auxiliary fuel pump 35 drive is turned off to stop the auxiliary fuel discharge in step 108, and the auxiliary fuel pump 35 drive request flag and the auxiliary fuel pump 35 energization flag are reset in step 109, and the process proceeds to step 110. Temperature of thermistor SNS after auxiliary fuel is discharged at THS2
is set in the RAM of the microcomputer CPU, and in step 111, the temperature difference ΔTHS=THS1-THS2 of the thermistor SNS before and after the auxiliary fuel discharge is calculated, and in step 112, ΔTHS and ΔTHR, that is,
Thermistor when auxiliary fuel is discharged normally
The temperature ΔTHR, which is slightly lower than the temperature difference of SNS, is compared, and if ΔTHS is larger than ΔTHR, it is determined in step 113 that the auxiliary fuel discharge by the auxiliary fuel pump 35 is normal, and if ΔTHS is smaller than ΔTHR, it is determined in step 114.
It is determined that the auxiliary fuel discharge by the auxiliary fuel pump 35 is abnormal.

In this way, in the case of this embodiment, a thermistor is used for the fuel discharge confirmation sensor SNS, and the temperature difference immediately before and after the collision of the auxiliary fuel with the thermistor is set in advance in response to the temperature drop in the thermistor due to the application of the auxiliary fuel. By comparing the detected value with the measured value, detection errors can be reliably prevented.

In addition, in this abnormality determination, by using it together with the electrical abnormality determination shown in FIGS. 2 and 3, it is possible to immediately determine whether it is an electrical abnormality or a mechanical abnormality.

(Effect of the invention) The present invention is an auxiliary fuel that changes the output by applying auxiliary fuel to the impact position when the auxiliary fuel is discharged on the intake passage where the auxiliary fuel from the auxiliary fuel pump is discharged through the auxiliary nozzle. By installing a discharge confirmation sensor and determining that an auxiliary fuel pump is abnormal when an output signal corresponding to auxiliary fuel discharge is not generated from the auxiliary fuel discharge confirmation sensor when the auxiliary fuel pump is activated, the auxiliary fuel This has the effect that it is possible to reliably detect whether or not the auxiliary fuel is reliably discharged into the intake passage by the operation of the pump.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram that clearly shows the configuration of the present invention, Figure 2
The figure is a main part electrical circuit diagram devised as a countermeasure for the conventional example, and Figure 3 is a flowchart for its control.
Fig. 4 is an explanatory diagram of one embodiment of the present invention, Fig. 5 is its electrical circuit diagram, Fig. 6 is its main part electrical circuit diagram, Fig. 7 is its operating characteristic diagram, and Fig. 8 is its flowchart. It is a diagram. S1-Sn...Various sensors, SAP...Auxiliary fuel pump, 100...Intake passage, 101...Auxiliary nozzle, 102...Auxiliary fuel discharge confirmation sensor, 10
3... Abnormality determination means.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) When auxiliary fuel is discharged into the engine intake passage by operating the auxiliary fuel pump based on signals from various sensors corresponding to engine operating conditions, An auxiliary fuel discharge confirmation sensor that changes the output when auxiliary fuel is applied is installed at a collision position during auxiliary fuel discharge on the intake passage where auxiliary fuel is discharged through an auxiliary nozzle, and the auxiliary fuel pump is activated. An auxiliary fuel discharge detection device for an engine, comprising an abnormality determination means for determining that an auxiliary fuel pump is abnormal when an output signal corresponding to auxiliary fuel discharge is not generated from the auxiliary fuel discharge confirmation sensor. (2) The auxiliary fuel discharge detection device for an engine according to claim 1, wherein the auxiliary fuel discharge confirmation sensor is a temperature detection element that changes its output depending on temperature changes. (3) The auxiliary fuel discharge detection device for an engine according to claim (2) of the utility model registration, characterized in that the temperature detection element is a thermistor. (4) The auxiliary fuel discharge detection device for an engine according to claim (2) of the utility model registration, characterized in that the temperature detection element is a thermocouple. (5) The auxiliary fuel discharge detection device for an engine according to claim 1, wherein the auxiliary fuel discharge confirmation sensor is a pressure detection element that changes its output according to a change in pressure.