JPH0519022B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply system for an engine.

Generally, immediately after starting an engine, a warm-up operation is performed to warm up the engine, but in this case, it is desirable to keep the warm-up time relatively short in order to improve exhaust gas purification.
For example, conventionally, the target rotation speed during engine warm-up is set so that it gradually decreases as the engine temperature rises, and the actual engine rotation speed during warm-up matches the target rotation speed according to the engine temperature. The idea was to feedback-control the amount of intake air to increase the amount of air-fuel mixture supplied, thereby shortening the warm-up time (see Japanese Patent Laid-Open No. 160136/1983).

However, with such conventional fuel supply devices,
No consideration is given to the humidity of the intake air; if the humidity is high, the moisture content in the intake air will increase, and the combustion temperature of the air-fuel mixture in the engine will be lower than when the humidity is low. As a result, there was still a delay in warm-up, which resulted in problems such as deterioration of fuel efficiency and exhaust gas conditions. Even if the engine speed during warm-up is feedback-controlled to the target engine speed, there is a response delay until the engine speed converges to the target engine speed, and during this response delay, the engine speed decreases. There is a problem that causes a delay in warming up. Furthermore, if the humidity in the intake air is too high, it may not be able to be covered by feedback control.

By the way, as shown in Japanese Unexamined Patent Application Publication No. 51-105529, there are some devices that sense the humidity of intake air and change the fuel injection rate according to the humidity, but it does not always work regardless of warm-up operation. , the fuel injection rate is controlled, which leads to deterioration of fuel efficiency after warm-up.

This invention was made in view of the above-mentioned problems with the conventional technology. The air-fuel mixture supply amount is increased at a large increase rate when the engine is warmed up and the humidity of the intake air is low, and the air-fuel mixture supply amount is increased at a small increase rate when the engine is warmed up, and the increase in the air-fuel mixture supply amount is stopped after the engine is warmed up. To provide a fuel supply device for an engine capable of constantly shortening warm-up time regardless of the humidity state of intake air without causing deterioration of fuel efficiency after engine termination.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a fuel supply system for an engine according to an embodiment of the present invention. In the figure, reference numeral 1 denotes an intake passage, and a ventilator portion 1 is provided on the upstream side of the intake passage 1.
a is formed, and a fuel supply nozzle 2 is opened and provided in the ventilate portion 1a. An air cleaner 3 is disposed upstream of the intake passage 1, and an air duct 4 for introducing outside air is connected to the air cleaner 3.

Further, a throttle valve 5 that opens and closes depending on the amount of depression of an accelerator pedal (not shown) is disposed downstream of the ventilate portion 1a of the intake passage 1, and a locking lever 6 is disposed on the shaft 5a of the throttle valve 5. Fixed. A bent portion 7a at one end of an operating rod 7 abuts and engages with the lower end of the locking lever 6, and the other end of the operating rod 7 is fixed to the surface of the diaphragm 8a of the diaphragm device 8 on the first chamber 8b side. ing. A spring member 8d for biasing the diaphragm 8a to the left in the figure is disposed in the second chamber 8c of the diaphragm device 8, and one end of a pressure introduction passage 9 is connected to the second chamber 8c. The other end of the passage 9 is branched into two, one of which is connected to the downstream side of the throttle valve 5 of the intake passage 1, and the other is open to the atmosphere. A three-way switching valve 10 is interposed at a branch part of this pressure introduction passage 9, and the three-way switching valve 10 normally communicates the pressure introduction passage 9 with the atmosphere side, and while receiving the switching signal d, the pressure introduction passage 9 is communicated with the intake passage 1 side. Further, a solenoid 11 which is activated in response to a control signal h is attached to the diaphragm device 8, and a plunger 11a of the solenoid 11 is urged by a spring member 11b and projects into the second chamber 8c.

Further, in the figure, 12 is a warm-up sensor that detects the warm-up state of the engine from the temperature of the engine cooling water, and 13 is a warm-up voltage that receives the output a of the warm-up sensor 12 and generates a voltage b according to the warm-up state. A generation circuit 14 is a first set voltage generation circuit 15 that generates a voltage corresponding to the voltage b at the time of completion of warm-up as a reference voltage c.
compares the output voltage b of the warm-up voltage generation circuit 13 and the reference voltage c of the first set voltage generation circuit 14, and performs the above three-way switching only when the output voltage b is lower than the reference voltage c, that is, while the engine is warming up. Switching signal d to valve 10
This is the first comparator circuit that adds . Further, 16 is a humidity sensor provided in the air duct 4 and detects the humidity of the intake air, 17 is an intake humidity voltage generation circuit that receives the output e of the humidity sensor 16 and generates a voltage f proportional to the humidity of the intake air, and 18 is a humidity sensor that detects the humidity of the intake air. The voltage corresponding to the above voltage f when the intake air humidity is at the set value is the reference voltage g.
A second set voltage generation circuit 19 generates a voltage by comparing the output voltage f of the intake air humidity voltage generation circuit 17 and the reference voltage g of the second set voltage generation circuit 18,
When the output voltage f is higher than the reference voltage g, that is, when the humidity of the intake air is high, a control signal h is sent to the solenoid 11.
20 is the second comparison circuit that adds
11, 13 to 15, and 17 to 19, the air-fuel mixture is supplied to the engine at a large rate of increase when the engine is warmed up and the humidity of the intake air is high, and at a small rate of increase when the humidity is low. This is a mixture increasing device that increases the amount of air-fuel mixture.

Next, the operation will be explained.

While the engine is warming up, normally the accelerator pedal is hardly depressed and the throttle valve 5 is hardly opened or closed by the accelerator pedal. The warm-up voltage generating circuit 13 receives the output a of the warm-up sensor 12 and generates a voltage b according to the warm-up state,
The first comparison circuit 15 compares the output voltage b of the warm-up voltage generation circuit 13 with the reference voltage c of the first set voltage generation circuit 14. The temperature of the engine coolant is now low, and the output voltage b of the warm-up voltage generation circuit 13 is lower than the reference voltage c, so the first comparison circuit 15 applies the switching signal d to the three-way switching valve 10, and the switching valve 10 The pressure introduction passage 9 is switched from the atmosphere side to the intake passage 1 side for communication. Then, the second diaphragm device 8
The negative pressure of the intake passage 1 is introduced into the chamber 8c via the pressure introduction passage 9, and the diaphragm 8a is connected to the spring member 8.
The solenoid 11 deforms and moves to the right in the figure against the spring force d until it comes into contact with the plunger 11a of the solenoid 11, and the operating rod 7 also moves to the right, and the operating rod 7 is moved through the locking lever 6. Throttle valve 5
open. Therefore, while the engine is warming up, the amount of intake air increases, and the amount of fuel supplied from the nozzle 2 increases accordingly, thereby increasing the amount of air-fuel mixture supplied.

At this time, the humidity sensor 16 detects the humidity of the intake air, and the intake air humidity voltage generation circuit 17 detects the humidity of the intake air.
The second comparison circuit 19 receives the output e of the intake air humidity voltage generating circuit 17 and generates a voltage f proportional to the humidity of the intake air. Compare. When the humidity of the intake air is higher than the set value, the output voltage f becomes higher than the reference voltage g, so the second comparison circuit 19
applies a control signal h to the solenoid 11, and the solenoid 11 attracts the plunger 11a against the spring force of the spring member 11b. Then, in the diaphragm device 8, the amount of movement of the diaphragm 8a until it comes into contact with the plunger 11a is large, and the opening degree of the throttle valve 5 also becomes large, so that the amount of the air-fuel mixture is increased at a large rate of increase. On the other hand, when the humidity of the intake air is below the set value, the output voltage f of the intake air humidity voltage generation circuit 17 is lower than the reference voltage g, the second comparison circuit 19 does not generate the control signal h, and the solenoid 11 The plunger 11a protrudes into the second chamber 8c of the diaphragm device 8 by the spring force of the spring member 11b, and as a result, the amount of movement of the diaphragm 8a becomes small, and the opening degree of the throttle valve 5 does not increase significantly, so that the air-fuel mixture The rate of increase will be smaller.

Furthermore, when the engine is warmed up, the temperature of the engine cooling water becomes high and the output voltage b of the warm-up voltage generation circuit 13 becomes higher than the reference voltage c.
The comparison circuit 15 stops outputting the switching signal d, and
The three-way switching valve 10 connects the pressure introduction passage 9 to the atmosphere again, atmospheric pressure is introduced into the second chamber 8c of the diaphragm device 8 via the pressure introduction passage 9, and the diaphragm 8a deforms and returns to the left. Operation rod 7
The valve also moves to the left, the engagement between the bent portion 7a of the operating rod 7 and the locking lever 6 is released, and the opening degree of the throttle valve 5 returns to the idle opening degree, thereby increasing the amount of air-fuel mixture. will be stopped.

In the device of this embodiment as described above, the air-fuel mixture is supplied at a large increase rate when the humidity of the intake air is above the set value when the engine is warmed up, and at a small increase rate when the humidity of the intake air is below the set value. Since the amount is increased, the combustion temperature of the air-fuel mixture can be kept almost constant despite changes in the humidity of the intake air, and the warm-up time can be controlled almost optimally, and fuel efficiency and exhaust gas purification can also be maintained satisfactorily. In addition, after warm-up, water evaporates depending on the engine temperature and the influence of humidity is almost eliminated. Deterioration of fuel efficiency can be prevented.

FIG. 2 shows a second embodiment of the present invention, in which the same reference numerals as in FIG. 1 indicate the same elements as in the same figure. However, in this embodiment, a bypass passage 21 is formed in the intake passage 1 to bypass the throttle valve 5, and the bypass passage 21 is provided with a proportional solenoid 22 operated by a control signal k. Plunger 22a of this proportional solenoid 22
is biased by the spring force of the spring member 22b and protrudes into the bypass passage 21, and the opening area of the bypass passage 21 changes depending on the amount of protrusion of the plunger 22a.

In addition, in the figure, 23 receives the output b of the warm-up voltage generation circuit 13, and the third
A first open circuit 24 generates a voltage i as shown in FIG. The second function circuit 25 that generates the signal j is an arithmetic circuit that multiplies the outputs i and j of both the function circuits 23 and 24 to generate the control signal k.

Next, the operation will be explained.

When the engine is warmed up, the first function circuit 23 receives the output b of the warm-up voltage generation circuit 13, and as shown in FIG. On the other hand, the second function circuit 24 receives the output f of the intake air humidity voltage generation circuit 17, and as shown in FIG. 3b, the value increases as the humidity of the intake air increases. The arithmetic circuit 25 generates a correction coefficient signal j that increases, and the arithmetic circuit 25
Multiply the outputs i and j of 3 and 24. At this time, the value of the correction coefficient signal j increases as the humidity of the intake air increases, so that the control signal k of the arithmetic circuit 25 increases as the humidity of the intake air increases even at the same cooling water temperature. Then, the proportional solenoid 22 receives the control signal k and attracts the plunger 22a with a suction force corresponding to the magnitude of the control signal k, and the plunger 22a moves to the right in the figure in response to the suction force against the spring force of the spring member 22b. , the bypass passage 21 is a plunger 22
The opening area corresponds to the amount of protrusion of a, and the amount of air-fuel mixture supplied to the engine through this bypass passage 21 is increased. Therefore, when the engine is warmed up, even if the cooling water temperature is the same, the higher the humidity of the intake air, the smaller the amount of protrusion of the plunger 22a and the larger the air-fuel mixture increase rate. As the amount of protrusion of 22a increases, the air-fuel mixture increase rate decreases.

Therefore, in the device of this embodiment, the air-fuel mixture increase rate is continuously adjusted according to the humidity of the intake air, so that the warm-up time can always be maintained at the optimum level even if the humidity fluctuates. .

In the above embodiment, the air-fuel mixture increasing device is constructed from a hardware circuit, but the air-fuel mixture increasing device may of course be constructed using a microcomputer. Further, the warm-up state of the engine may be detected not from the temperature of the engine cooling water but from the temperature of the engine exhaust system.

As described above, according to the engine fuel supply device according to the present invention, in an engine that increases the amount of air-fuel mixture supplied during warm-up, the higher the humidity of the intake air when the engine is warmed up, the greater the increase in the amount of air-fuel mixture supplied. At a rate of
By increasing the air-fuel mixture supply amount at a smaller increase rate as the humidity of the intake air is lower, and stopping the increase in the air-fuel mixture supply amount after the end of warm-up, unnecessary increases in the amount of air-fuel mixture supply after the end of warm-up are avoided. The warm-up time can be maintained at an optimum level even if the humidity of the intake air fluctuates without causing a deterioration in fuel efficiency, resulting in improved fuel efficiency and exhaust gas purification.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an engine fuel supply system according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of an engine fuel supply system according to another embodiment of the invention, and FIGS. 3a and 3b are The first and second in the above device
FIG. 3 is an output characteristic diagram of a functional circuit. 12... Warm-up sensor, 16... Humidity sensor, 20...
Mixture increasing device.

Claims (1)

[Claims] 1. A humidity sensor that detects the humidity of intake air, a warm-up sensor that detects the warm-up state of the engine, and a sensor that receives the outputs of both the humidity sensor and warm-up sensor and detects the warm-up state and intake air humidity when warming up the engine. The amount of air-fuel mixture supplied to the engine is increased at a larger rate as the intake air humidity is higher, and at a smaller rate as the intake air humidity is lower, while stopping the increase in the amount of air-fuel mixture supplied after warm-up. An engine fuel supply device comprising: