JPS59190460A - Secondary intake-air supply device for internal- combustion engine - Google Patents

Abstract

PURPOSE:To allow the air-fuel ratio of engine mixture to avoid becoming overrich to aim at enhancing the performance of an engine, by maintaining the opening degree of an air-control valve at its middle value when the engine is in the cold condition. CONSTITUTION:Intake-air is fed to an engine 4 from an atmospheric air suction port 1 through an intake-air passage 3. Gas pressure is fed from a three-way solenoid selector valve 13 to an air control valve 12 connected to a secondary intake-air passage 11. A solenoid 13a is connected to a control circuit 22 through a drive circuit 21. An oxygen sensor 23 is connected to the control circuit 22. The opening degree of the air-control valve 12 is maintained at its middle value when the engine is in the cold condition. With this arrangement, the air-fuel ratio of the engine mixture may avoid becoming overrich, and therefore, the performance of the engine may be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake secondary air supply device for an internal combustion engine.

In an internal combustion engine equipped with a three-way catalyst in the exhaust system for exhaust gas purification, when the air-fuel ratio of the supplied mixture is close to the stoichiometric air-fuel ratio (for example, 14.7:1) (-1), the three-way catalyst is Since this is effective, the air-fuel ratio is controlled to around the stoichiometric air-fuel ratio according to the composition of exhaust gas and the operating state of the engine.

There is an intake secondary air supply device that performs this air-fuel ratio control by providing an intake secondary air passage communicating downstream of the throttle valve and controlling the amount of secondary air therein.

As the intake secondary air supply device, an air control valve that changes the passage cross-sectional area according to the magnitude of the gas pressure in the pressure receiving chamber is installed in the intake secondary air passage (1). The actual air-fuel ratio is determined from the oxygen concentration detected by a concentration sensor, and when the air-fuel ratio is rich, a first control pressure capable of closing the air control valve is supplied to the pressure receiving chamber to determine the flow passage cross-sectional area. The air-fuel ratio is gradually increased, and when the air-fuel ratio is lean, a second control pressure that can close the air control valve is supplied to the pressure-receiving chamber, and the cross-sectional area of the flow path is gradually decreased, resulting in a pneumatic integral operation. The present applicant has already proposed a device that performs air-fuel ratio control.

In such an intake secondary air supply device, a so-called pour-in type sensor is sometimes used as the oxygen concentration sensor. The output voltage of a pour-in type oxygen concentration sensor decreases as the atmosphere becomes leaner. By the way, when the engine is cold, the oxygen concentration sensor itself is at a low temperature, so the internal resistance is large and the sensor is in an inactive state. Therefore, even in a lean atmosphere, the output voltage of the oxygen concentration sensor remains below the threshold voltage and remains at the theoretical empty temperature. The voltage does not drop below the reference voltage corresponding to combustion. As the oxygen concentration sensor output voltage VO2 warms up, it drops as shown by the solid line A in Figure 1 in a rich atmosphere, and drops below the reference voltage Vr as shown in the broken line B in Figure 1 in a lean atmosphere. be.

Therefore, unless the activation determination voltage V1, which is smaller than the reference voltage Vr, is reached in a lean atmosphere, it cannot be said that the oxygen concentration sensor has been activated, and the air-fuel ratio cannot be controlled to the stoichiometric air-fuel ratio. However, when the engine is cold, the output voltage of the oxygen concentration sensor is higher than the reference voltage, so it is determined that the air-fuel ratio is rich, and the first control pressure continues to be supplied to the pressure receiving chamber of the air control valve. Therefore, the air control valve is fully opened and the intake secondary air is supplied to the engine, resulting in an over-lean air-fuel ratio (18) and deterioration of driving performance.

Therefore, it is an object of the present invention to provide an intake secondary air supply device that improves the operating performance of the engine when it is cold.

The intake secondary air supply device according to the present invention is characterized in that the opening degree of the air control valve is maintained at an intermediate opening degree when the engine is cold.

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

In the intake secondary air supply device d3, which is an embodiment of the present invention shown in FIG.
: Sea urchins are turning. A throttle valve 5 is installed in the intake passage 3, a venturi 6 of a carburetor is formed upstream of the throttle valve 5, and a choke valve 7 is provided in the −F flow further from the venturi 6. A negative pressure detection hole 8 is formed in the inner wall surface of the intake passage 3 downstream of the throttle valve 5, and a negative pressure detection hole 9 is also formed in the bench stiffener 6.

The downstream side of the throttle valve 5, that is, the intake manifold and the vicinity of the air discharge port of the air cleaner 2 are communicated with each other by an intake secondary air passage 11. An air control valve 12 is provided in the intake secondary air passage 11, and the air control valve 12 receives a negative pressure W12a corresponding to the above-mentioned pressure receiving character, a valve chamber 12b forming a part of the intake secondary air passage 11, and a negative pressure. A diaphragm 12c forming a part of the chamber 12a, a valve spring 12d provided in the negative pressure chamber 12a, and a valve spring 12d provided in the valve chamber 121) so as to close the intake secondary air passage 11. Ic valve body 12e is energized via
The flow path cross-sectional area of the intake secondary air passage 11 is changed according to the magnitude of the negative pressure acting on the negative pressure chamber 12a,
The cross-sectional area of the flow path increases as the negative pressure increases.

Gas pressure is supplied to the negative pressure chamber 12a of the air control valve 12 from the three-way solenoid valve 13 through the pressure passage 14. The solenoid valve 13 has a solenoid 13a and a negative pressure chamber 12.
The valve chamber 13b is in communication with the valve chamber 13a through the pressure horn passage 14, and the valve body 13C is provided in the valve chamber 13b and magnetically coupled to the solenoid 13a. The valve chamber 13b communicates with the negative pressure control section 31 that generates the first control pressure via the negative pressure passage 15, and also communicates with the negative pressure control section 31 that generates the first control pressure, and also communicates with the negative pressure control section 31 that generates the first control pressure.
The air control valve 12 is in communication with the air control valve 12 via an atmospheric pressure passage 16. When the solenoid 13 is de-energized, the negative pressure passage 15 side is closed and the pressure passage 14 and the atmospheric pressure passage 16 communicate with each other via the valve chamber 1311, and when the solenoid 13 is energized, the atmospheric pressure passage 16 side is closed and the pressure passage 14 and the negative pressure passage are communicated with each other via the valve chamber 1311. 15 is connected. d3, negative pressure passage 15 has A
A refill 17 is provided, and an A refill 19 is provided in the atmospheric pressure passage 16.

A control circuit 2 is connected to the solenoid 13a via a drive circuit 21.
2 are connected. An oxygen concentration sensor 23 provided in the air passage 10 of the engine 4 is connected to the control circuit 22 . The oxygen concentration sensor 23 is designed to generate a voltage at a level corresponding to the oxygen concentration in the exhaust gas.

The negative pressure control unit 31 includes a negative pressure responsive adjustment valve 32 and an air valve 3.
3, the adjustment valve 32 and the air valve 33 are connected to the negative pressure chamber 3.
2a, 33a, valves ff1321), 33b, diaphragms 32c, 33c, valve springs 32d, 33d, and valve bodies 32e, 33e, respectively. The negative pressure chamber 32a is provided in the middle of the control intake passage 35 from the popular intake port 34 with a filter to the downstream of the throttle valve 5, and the valve chamber 33b is located in the control intake passage 35 downstream of the negative pressure chamber 32a. There is. Valve body 33
e is attached to the valve spring 33d so as to close the control intake passage 35.
: It is energized via the diaphragm 33C. The negative pressure chamber 33a communicates with the negative pressure detection hole 8 through the negative pressure passage 36, and the valve chamber 32b communicates with the negative pressure detection hole 9 through the negative pressure passage 37. Further, the valve chamber 3211 is communicated with the negative pressure passage 36, and the valve spring 32d connects the valve body 32e via the diaphragm 32C so that the valve body 32e closes the passage from the valve chamber 32b to the negative pressure passage 36. (=I have a lot of people.

In addition, orifices 38 and 39 are provided on the upstream side of the negative pressure chamber 32a of the control intake passage 35, and an A refill 40 is provided on the downstream side.
An orifice 41 is provided in the negative pressure passage 36, and an orifice 42 is provided in the negative pressure passage 37.
The a-side negative pressure passage 36 and the negative pressure passage 15 communicate with each other.

A refill 39 has orifice 38J, Rimo's popular intake port 3
An auxiliary control intake passage 43 is provided on the J'3 side so as to bypass and cover the orifice 39. A solenoid valve 44 is installed in the auxiliary control intake passage 43, and a solenoid 44. A control circuit 46 is connected to a via a drive circuit/45. The solenoid valve 44 is a solenoid 44
When the solenoid a is de-energized, the auxiliary control intake passage 43 is brought into communication, and when the solenoid 4/la is energized, the valve is closed and the auxiliary control intake passage 43 is closed.

On the other hand, a cold N1 water temperature sensor 47 is provided to detect the cooling water temperature of the engine 4.
7 generates an output voltage at a level corresponding to the temperature of the cold M1 water, and the output voltage is supplied to the control circuit 46.
There is.

In the intake secondary air supply device according to the present invention having such a configuration, first, the operation of the negative pressure control section 31 will be explained.

The negative pressure passage 36 is opened from the negative pressure detection hole 8 by the operation of the engine 4.
When the negative pressure Ps acts on the negative pressure chamber 33a through the negative pressure Pe, the valve body 3
3e moves in the valve opening direction.

When the air valve 33 opens, outside air flows from the atmospheric air intake port 34 through the control intake passage 35 into the intake passage 3 downstream of the throttle valve 5 . The negative pressure P1 of the negative pressure chamber 32a through which this outside air passes and the negative pressure P2 of the valve chamber 33b are connected to the orifice 38, 39 and the solenoid valve 4.
4 and the aperture ratio of the A refill 40.

Next, the negative pressure Pv acting on the valve chamber 32b from the negative pressure detection hole 9
When the differential pressure between and negative pressure P+ is greater than the biasing force exerted by the valve spring 32d, the valve body 32e moves in the valve opening direction. Adjustment valve 32
When the valve is opened, a part of the negative pressure pv passes through the orifice 41 and becomes a negative pressure pe, which acts on the negative pressure chamber 12a when the solenoid valve 13 is operated.

Next, as the negative pressure pe decreases, the 1if1 degree of the air valve 33 decreases, and the amount of air flowing through the control intake path 35 also decreases.

Due to this decrease in the amount of air, the negative pressure P1 in the negative pressure chamber 32a decreases, and the regulating valve 32 deviates from the closed state by 416 degrees, causing the negative pressure pe to decrease.
rises again and the same operation as above is repeated, and this repeated operation is carried out at high speed, so the negative pressure 1) y and pe
The pressure ratio between the negative pressures P1 and P2 becomes equal to the pressure ratio between the negative pressures P1 and P2.

Therefore, when the main intake air amount of the engine 4 is small (0) (this is because the negative pressure P1 is higher than the negative pressure PV, the opening degree of the regulating valve 32 becomes larger and the negative pressure pe becomes lower, and as the main intake air amount increases, Since the negative pressure pv increases, the opening degree of the regulating valve 32 becomes smaller and the negative pressure pc increases.The negative pressure pe acts on the negative pressure chamber 12a as well as the negative pressure chamber 33a when the solenoid valve 13 is operated, and the air valve 33, When the solenoid valve 13 is activated, the amount of air flowing through the control intake passage 35 to open the air control valve 12 is proportional to the amount of secondary air flowing through the secondary intake air passage 11; Main intake air amount to engine 4 and air control valve 1
By opening the valve 2, the amount of secondary air flowing through the intake secondary air passage 11 is proportionally increased. Therefore, the negative pressure pe is proportional to the main intake air amount.
This is the first control pressure that causes the second air to be introduced downstream of the throttle valve 5 in the engine intake passage 3.

Next, the operation of the control circuit 22 will be explained according to the operation flow diagram of FIG.

When an ignition switch (not shown) is turned on and power is supplied, the control circuit 22 first reads the output voltage level of the oxygen concentration sensor 23 (step 1). The oxygen temperature sensor 23 is a pour-in type sensor, and the output voltage VO2 decreases as the atmosphere becomes leaner. Oxygen temperature sensor 23 (output voltage V
After reading O2, the air-fuel ratio of the air-fuel mixture is determined from this output voltage VO2 (step 2). In this determination operation, it is determined whether the air-fuel ratio is rich or lean depending on whether the output voltage VO2 of the oxygen m degree Lonza 23 is greater than the reference voltage Vr corresponding to the stoichiometric air-fuel ratio. VO2
<Vr, it is determined that the air-fuel ratio is lean, and a lean signal is sent to the drive circuit 21 to control the air-fuel ratio in the rich direction.
(Step 3). On the other hand, in the case of VO2≧V, it is determined that the air-fuel ratio is rich, and a rich signal is supplied to the drive circuit 21 to control the air-fuel ratio in a lean direction (
Step 4).

When a lean signal or a rich signal is supplied from the control circuit 22 to the drive circuit 21 in this way, the drive circuit 21 de-energizes the solenoid 13a in response to the lean signal and de-energizes the solenoid valve 1.
3 is rendered inoperative, and the solenoid valve 13 is rendered operative by energizing the solenoid 13a in response to the rich signal.

Now, when the output of the control circuit 22 is reversed from the lean signal to the rich signal, the solenoid valve 13 becomes activated and closes the atmospheric pressure passage 16 side, thereby closing the pressure passage 14 and the negative pressure passage 15.
communicate with. Then, since the negative pressure pe is supplied from the negative pressure control unit 31 to the negative pressure chamber 12a via the A-refrigerator 17, the negative pressure in the negative pressure chamber 12a gradually approaches the negative pressure pe, and the air control valve 12, that is, the cross-sectional area of the intake secondary air passage 11 gradually increases, and the amount of secondary air increases.

When the negative pressure in the negative pressure chamber 12a becomes equal to the negative pressure 1, the amount of secondary air flowing through the intake secondary air passage 11 is proportional to the main intake air amount, and the amount of secondary air flowing through the intake secondary air passage 11 is proportional to the main intake air amount to the engine 4. Next air is supplied.

Next, when the output of the control circuit 22 is reversed from the rich signal to the lean signal, the solenoid valve 13 becomes inoperative, closing the negative pressure passage 15 side and allowing the pressure passage 14 and the atmospheric pressure passage 16 to communicate with each other. Then, since atmospheric pressure is supplied to the negative pressure chamber 12a through the orifice 19, the negative pressure in the negative pressure chamber 12a gradually approaches atmospheric pressure, and the flow passage cross-sectional area of the secondary intake air passage 11 gradually decreases. The amount of secondary air also decreases. Negative pressure chamber 1
When the pressure inside 2a becomes almost equal to atmospheric pressure, the air control valve 1
2 is because the valve closes and the secondary intake air passage 11 is blocked.
Then, the supply of secondary air to the engine 4 stops.

Therefore, when controlling the air-fuel ratio to the stoichiometric air-fuel ratio, Fig. 4 (
As shown in a), the rich signal and the lean signal are generated in alternating communication, so the opening degree of the air control valve 12 is the fourth output)
As shown in the figure, it increases when a rich signal occurs and decreases when a lean signal occurs. Therefore, since the flow passage cross-sectional area of the intake secondary air passage 11 and the secondary air 11 change similarly, the air-fuel ratio control center value becomes the stoichiometric air-fuel ratio.

Next, the operation of the intake secondary air supply system according to the present invention when the engine 4 is cold will be explained.

Since the oxygen concentration sensor 23 is in an inactive state when the engine 4 is cold, the output voltage VO2 of the oxygen concentration sensor 23 is lower than the reference voltage Vr. As a result, the control circuit 22 generates a rich No. 15, and the negative pressure Pe is applied from the negative pressure control section 31 to the negative pressure chamber 12a of the air control valve 12 in the negative pressure passage 15.
, the solenoid valve 13 and the pressure horn passage 14.

On the other hand, when the engine 4 is cold, the output voltage VtW of the cooling water temperature sensor 47 is lower than the predetermined voltage V1.

The control circuit 46 supplies a valve closing signal to the drive circuit 45 when the output voltage Vtw is lower than a predetermined voltage (1), and in response to this valve closing signal, the drive circuit 45 supplies a heavy duty signal to the solenoid 44a. This causes the solenoid valve 44 to close. When the solenoid valve 44 is closed, the auxiliary control intake passage 43 is closed and the flow passage cross-sectional area of the control intake passage 35 is reduced, so the proportion of air amount is reduced compared to when the solenoid valve 44 is open. Since the opening degree increases, the leakage of the negative pressure PB to the negative pressure passage 37 increases the most, so the negative pressure pe decreases to a size that causes the air control valve 12 to reach an intermediate opening degree.

Therefore, when the engine 4 is cold, the intake secondary air amount is limited, so the air-fuel ratio can be brought closer to the base air-fuel ratio (13) of the carburetor.

As described above, in the intake secondary air supply system J5 of the present invention, the opening degree of the air control valve is maintained at an intermediate opening degree when the engine is cold, thereby avoiding overleaning of the air-fuel ratio. Therefore, driving performance can be improved.

In the intake secondary air supply system according to the present invention shown in FIG. There is also the advantage that the amount of secondary air that is pulled to the intermediate opening can be avoided by changing the intermediate opening in proportion to the amount of intake air.

In addition, in the intake secondary air supply device of the present invention, the engine cold time is not limited to being determined from the engine cold u + water temperature as in the above embodiment, but also based on the intake air temperature, the inactive state of the oxygen concentration sensor, and the determination after the engine is started. It may be determined based on the elapsed time or the catalyst temperature.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the output voltage characteristics during warm-up of a pour-in type oxygen concentration sensor, Fig. 2 is a configuration diagram showing an embodiment of the present invention, and Fig. 3 is a diagram showing the control circuit in the device of Fig. 2. FIG. 4 is a flowchart showing the operation, and is a diagram showing changes in the opening degree of the air control valve in the apparatus of FIG. 2. Explanation of symbols of main parts 2... Air cleaner 3... Intake path 5... Throttle valve 6.
...Venturi 8.9...Negative pressure detection hole 10...Exhaust passage 11...Intake secondary air passage 12...Air control valve 13.4/l...Solenoid valve 14...Pressure passage 15.36.37...Negative pressure passage 16...
・Atmospheric pressure passage 17, 19, 38 to 42... Orifice 2
3...Oxygen temperature sensor 31...Negative pressure control unit Applicant Honda Motor Co., Ltd. Agent Patent attorney Motohiko Fujimura O2 V+ V+ Figure 3 Figure 1■ \ B ----- ---One hour Figure 4

Claims (1)

[Scope of Claims] (1) A secondary intake air passage is provided in an intake secondary air passage communicating downstream of a throttle valve of an internal combustion engine, and the cross-sectional area of the intake secondary air passage is adjusted according to the magnitude of gas pressure in a pressure receiving chamber. an air control valve that changes the air-fuel ratio; a determining means that determines the air-fuel ratio from the composition of engine exhaust gas and generates an air-fuel ratio signal; and a control means that controls the opening degree of the air-fuel ratio according to the content of the air-fuel ratio signal. An intake secondary air supply device, characterized in that the opening degree of the air control valve is maintained at an intermediate opening degree when the engine is cold. 2) The determination means has a flow-in type oxygen temperature sensor installed in the υ1 air system, and is configured to determine the air-fuel ratio based on the output voltage level of the oxygen concentration sensor. The intake secondary air supply device according to claim 1. (3) The control means includes a first control pressure generation source that generates a first control pressure for opening the air control valve; a second control pressure generation source that generates a second control pressure for closing the air control valve; and a second control pressure source that generates either the first or second control pressure in accordance with the content of the air-fuel ratio signal. and a communication means for supplying the first control pressure to the first control pressure when the engine is cold, and wherein the first control pressure during the cold state is reduced overall compared to after the engine is warmed up.
The intake secondary air supply device described in Section 1. (4) The first control pressure generation source is near the throttle valve in the engine intake passage or a first negative pressure passage extending downstream of the throttle valve, etc.
A second negative pressure passage extending from inside the venturi upstream of the throttle valve, a control intake passage extending from the atmosphere intake port to the downstream of the throttle valve, and a first negative pressure chamber are provided in the middle of the control intake passage. One valve palm communicates with the second negative pressure passage, and the first negative pressure passage and the second negative pressure passage are connected to the first negative pressure passage according to the pressure difference between the first negative pressure chamber and the first valve chamber. a negative pressure responsive regulating valve communicated via a valve chamber, a second negative pressure chamber communicating with the first negative pressure passage, and a second valve chamber downstream from the first negative pressure chamber in the middle of the control intake passage; a negative pressure-responsive air valve that is provided in the second negative pressure chamber and connects the control intake passage with an opening degree depending on the pressure difference between the second negative pressure chamber and the second valve chamber, and acts on the second negative pressure chamber. A negative pressure is outputted as the first control pressure, and a flow passage cross-sectional area of a control intake passage upstream from the first negative positive chamber is reduced during the cold state. The intake secondary air supply device according to scope 3. (5) The cold time includes at least one of the following: the engine cooling water temperature, the intake air temperature, the inactive state of the oxygen concentration sensor, the elapsed time after engine startup, and the temperature of the catalyst installed in the exhaust system.
The intake secondary air supply device according to claim 1, wherein the intake secondary air supply device is detected based on.