JPH02181057A - Intake secondary air supplying device for internal combustion engine - Google Patents

Abstract

PURPOSE:To restrain variation of air-fuel ratio by stopping supply of secondary air into an intake system of an internal combustion engine due to the detected signal from an exhaust gas sensor, during a prescribed time after beginning of operation of an EGR valve adjusting an exhaust reflux quantity to the intake system of the engine. CONSTITUTION:An internal combustion engine comprises a secondary air supplying device 4 for intake air and an EGR device 6. The secondary air supplying device 4 actuates a secondary air control valve 20 to open or close a secondary air supply passage 18 by a control part 22, based on the detected signal of an oxygen sensor 24 provided in an exhaust passage 16 of the internal combustion engine 2, hereby, the secondary air supply into an intake passage 14 of the engine 2 is controlled to feed back. Meanwhile, an EGR valve 28 is provided in an EGR passage 26 in the EGR device 6. In this case, during a prescribed time after beginning of operation of the EGR valve 28, supply of the secondary air to the intake passage 14 due to the detected signal of the oxygen sensor is controlled to be stopped.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an intake secondary air supply device for an internal combustion engine, and in particular to an apparatus for suppressing fluctuations in the air-fuel ratio when the internal combustion engine shifts to an accelerated operating state. The present invention relates to an intake secondary air supply device for an internal combustion engine that can avoid deterioration in drivability.

[Conventional technology]

In internal combustion engines for vehicles, operating conditions vary widely and rapidly. In order to meet such operating conditions and to reduce the fuel consumption rate and the value of harmful exhaust gas components, it is necessary to appropriately adjust the air-fuel ratio. As a device for adjusting the air-fuel ratio to such an appropriate level, there is an intake secondary air supply device. The intake secondary air supply device includes an exhaust sensor that detects the concentration of exhaust gas in the exhaust gas, such as an 02 sensor that detects the oxygen concentration in the exhaust gas, in the exhaust system of the internal combustion engine, and supplies the air to the intake system based on the detection signal of the 02 sensor. The air-fuel ratio is adjusted to a predetermined value by feeding back and controlling the secondary air.

Such devices are disclosed in Japanese Patent Application Laid-open Nos. 52-153032 and 62-85159. The one disclosed in Japanese Patent Application Laid-Open No. 51-153032 is
The response delay is prevented by controlling the secondary air using a delay time sensor that detects the detection delay time of the exhaust sensor during acceleration/deceleration operation of the internal combustion engine. The system disclosed in Japanese Patent Application Laid-Open No. 62-85159 controls the secondary air by the detection signal of the driving state sensor, regardless of the detection signal of the exhaust sensor during acceleration operation.
This prevents response delays.

[Problem that the invention seeks to solve]

By the way, internal combustion engines are equipped with an EGR device that dilutes the intake air by recirculating a portion of the exhaust gas into the intake system, lowering the flame propagation speed and maximum combustion temperature, and reducing NOx in the exhaust gas. There is something. This EGR device is
The amount of exhaust gas recirculated to the intake system is adjusted by the EGR valve. The EGR valve is operated using intake negative pressure, etc.
The amount of exhaust gas recirculation is adjusted depending on the operating state of the internal combustion engine, and for example, the amount of exhaust gas recirculation is adjusted in proportion to the load.

However, when the EGR valve operates, the air-fuel ratio changes due to the recirculated exhaust gas and becomes lean. In this case, the internal combustion engine shifts to an acceleration operation state, especially a slow acceleration operation state, and the EG
When the R valve starts operating, the air-fuel ratio fluctuates significantly and becomes lean, causing shocks, surges, etc., and there is a problem in that drivability is deteriorated. At this time, if secondary air is immediately supplied to adjust the air-fuel ratio to a predetermined value with acceleration driving, the air-fuel ratio will become larger due to the supply of secondary air together with the recirculation of exhaust gas due to the start of operation of the EGR valve. This has the disadvantage of causing fluctuations and leanness, further deteriorating drivability.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to realize an intake secondary air supply device for an internal combustion engine that can suppress fluctuations in the air-fuel ratio when the internal combustion engine shifts to an accelerated operating state, and can avoid deterioration in drivability. It is in.

[Means for solving problems]

To achieve this object, the present invention provides an internal combustion engine that adjusts the air-fuel ratio to a predetermined value by controlling secondary air supplied to the intake system of the internal combustion engine based on a detection signal from an exhaust sensor provided in the exhaust system of the internal combustion engine. In the intake secondary air supply system of the engine, for a predetermined period of time from the start of operation of the EGR valve that adjusts the amount of exhaust gas recirculated to the intake system of the internal combustion engine, the exhaust gas is supplied to the intake system of the internal combustion engine according to the detection signal of the exhaust sensor. The present invention is characterized in that a control means for suspending control of the supply of secondary air is provided.

[Effect]

According to the configuration of the present invention, the control means controls the intake system of the internal combustion engine based on the detection signal of the exhaust sensor for a predetermined period of time from the start of operation of the EGR valve that adjusts the amount of exhaust gas recirculated to the intake system of the internal combustion engine. By stopping the control of the supply of secondary air, the air is reduced due to the secondary air being supplied together with the exhaust gas recirculated by the EGR valve that started operating when the internal combustion engine transitioned to an accelerating operating state. Large fluctuations in fuel ratio can be suppressed.

〔Example〕

Next, embodiments of the present invention will be described in detail based on the drawings.

1 and 2 show an embodiment of the invention. In FIG. 1, reference numeral 2 denotes an internal combustion engine, which has an intake secondary air supply device 4 and an EGR device 6. The internal combustion engine 2 mixes air taken in from an air cleaner 8 with fuel in a carburetor 10 to generate an air-fuel mixture, and passes this air-fuel mixture through a throttle valve 12.
The amount of fuel is supplied through the intake passage 14 and combusted. Exhaust gas produced by combustion in the internal combustion engine 2 is exhausted to the outside via the exhaust passage 16.

The intake secondary air supply device 4 includes a secondary air supply passage 1 whose starting end communicates with the air cleaner 8 and whose end communicates with an intake passage 14 downstream of the throttle valve 12, bypassing the throttle valve 12 of the carburetor 10.
8 is provided, and a secondary air control valve 20 is provided in the middle of this secondary air supply passage 18. This secondary air control valve 20 is
It is connected to a control section 22 which is a control means. Control unit 22
An 02 sensor 24, which is an exhaust sensor provided in the exhaust passage 16, is connected to the exhaust passage 16. Thereby, the intake secondary air supply device 4 operates the secondary air control valve 20 by the control unit 22 based on the detection signal of the 02 sensor 24 provided in the exhaust passage 16 of the internal combustion engine 2. The EGR device 6 adjusts the air-fuel ratio to a predetermined value by opening and closing the air and feeding back the secondary air supplied to the intake passage 14 of the internal combustion engine 2 to adjust the air-fuel ratio to a predetermined value. An EGR passage 26 for exhaust gas recirculation that opens at the end in the intake passage 4 on the downstream side of the throttle valve 12 is provided. An EGR valve 28 for adjustment is provided. The EGR valve 28 includes a main body 30, a diaphragm 34 that defines a pressure chamber 32 within the main body 30, a spring 36 that presses the diaphragm 34 to displace the pressure chamber 32 in the expansion direction, and a rod attached to the diaphragm 34. 38, and a valve body 40 for opening and closing the EGR passage 26. The pressure chamber 32 has an inductor that opens at its starting end in the intake passage 14 located slightly upstream when the throttle valve 12 of the carburetor 10 is closed and located downstream when the throttle valve 12 is opened to a predetermined opening. aisle 4
2 is opened at the end. Thereby, the EGR device 6 opens and closes the EGR passage 26 by moving the valve body 40 forward and backward by the intake negative pressure acting on the pressure chamber 32 of the EGR valve 28 from the EGR passage 26 and the elastic force of the spring 36. Adjust the exhaust gas recirculation amount.

In this way, the detection signal of the 02 sensor 24 provided in the exhaust passage 16 of the internal combustion engine 2 causes the intake passage 1 of the internal combustion engine 2 to
As shown in FIG.
Control of the supply of secondary air to the intake passage 14 of the internal combustion engine 2 based on the detection signal of the 02 sensor 24 is stopped for a predetermined time t from the start of operation of the EGR valve 28 that adjusts the amount of exhaust gas recirculated to the internal combustion engine 2. Control means shall be provided. That is, the main body 30 of the EGR valve 28 is provided with an operation detection sensor 44 that detects the start of operation of the EGR valve 28, and the intake secondary air supply device 4
The controller 22 is connected to the controller 22 of the controller. When the control unit 22 detects the start of operation of the EGR valve 28 by the operation detection sensor 44, the predetermined time t from the start of operation of the EGR valve 28 is determined by the detection signal of the 02 sensor 24. The configuration is such that control of the supply of secondary air to the passage 14 is suspended.

Next, the effect will be explained.

The intake secondary air supply device 4 opens and closes the secondary air supply passage 18 by operating the secondary air control valve 20 in response to the detection signal of the 02 sensor 24 provided in the exhaust passage 16 of the internal combustion engine 2 by the control unit 22. The air-fuel ratio is adjusted to a predetermined value by feedhacking and controlling the secondary air supplied to the intake passage 14 of the internal combustion engine 2.

In addition, the EGR device 6 also connects the EGR passage 26 to the EGR valve 2.
The valve body 40 is moved forward and backward by the intake negative pressure acting on the pressure chamber 32 of No. 8 and the elastic force of the spring 36 to open and close the EGR passage 26 to adjust the amount of exhaust gas recirculation.

However, when the internal combustion engine 2 shifts to an acceleration operation state, particularly a slow acceleration operation state, and the EGR valve 28 of the EGR device 6 starts operating, the intake air The supply of secondary air by the secondary air supply device 4 causes the air-fuel ratio to fluctuate more and become leaner, which is disadvantageous in that it further deteriorates drivability.

Therefore, when the control unit 22 detects the start of operation of the EGR valve 28 by the operation detection sensor 44, as shown in D in FIG. Control of supply of secondary air to the intake passage 14 of the internal combustion engine 2 based on the detection signal is stopped. In other words, by shifting to the acceleration driving state, the EG
Control of the secondary air by the O2 sensor 24 is delayed for a predetermined time t after the R valve 28 starts operating, and after the predetermined time t has elapsed, normal control of the secondary air by the O2 sensor 24 is resumed.

In FIG. 2, A shows the change in the air-fuel ratio during accelerated operation of an internal combustion engine without an accelerator pump (not shown), and B shows the change in the air-fuel ratio during accelerated operation of the internal combustion engine with an accelerator pump. . In this manner, the air-fuel ratio of an internal combustion engine having an acceleration pump fluctuates more toward the Lynch side during acceleration operation than an internal combustion engine without an acceleration pump. In Fig. 2, C has an accelerating pump and 2
This figure shows changes in the air-fuel ratio of an internal combustion engine that controls air.

In this way, the air-fuel ratio can be adjusted to a predetermined value by controlling the secondary air and the fluctuation time can be shortened, but there is a problem in that the air-fuel ratio becomes lean when transitioning to an accelerated driving state.

Therefore, as shown by D in FIG. 2, the control section 22
The predetermined time t after the EGR valve 28 starts operating due to transition to the acceleration operation state is determined by the 02 sensor 24.
By stopping the secondary air control, the air-fuel ratio is increased by supplying secondary air together with the exhaust gas recirculated by the EGR valve 28 that starts operating when the internal combustion engine 2 shifts to an accelerating operation state. It is possible to suppress large fluctuations in

Therefore, fluctuations in the air-fuel ratio when the internal combustion engine 2 shifts to an accelerated operating state can be suppressed, thereby making it possible to alleviate shocks, surges, etc. and avoid deterioration in engine operability.

〔Effect of the invention〕

As described above, according to the present invention, the control means adjusts the amount of exhaust gas recirculated to the intake system of the internal combustion engine.
By suspending control of the supply of secondary air to the intake system of the internal combustion engine based on the detection signal of the exhaust sensor for a predetermined period of time after the start of operation of the R valve, operation is started when the internal combustion engine shifts to an accelerated operation state. It is possible to suppress large fluctuations in the air-fuel ratio due to the supply of secondary air together with the exhaust gas recirculated by the EGR valve.

Therefore, it is possible to suppress fluctuations in the air-fuel ratio when the internal combustion engine shifts to an accelerated operating state, thereby alleviating shocks, surges, etc., and avoiding deterioration in engine operability.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an intake secondary air supply system for an internal combustion engine showing an embodiment of the present invention. FIG. 2 is a diagram showing fluctuations in the air-fuel ratio in an accelerated driving state. In the figure, 2 is an internal combustion engine, 4 is an intake secondary air control device, 6 is an EGR device, 10 is a carburetor, 14 is an intake passage, 1
6 is an exhaust passage, 18 is a secondary air supply passage, 20 is a secondary air control valve, 22 is a control unit, 24 is an 02 sensor, 26 is an E
A GR passage, 28 an EGR valve, and 44 an operation detection sensor.

Claims (1)

[Claims] 1. Intake 2 of an internal combustion engine in which the air-fuel ratio is adjusted to a predetermined value by controlling secondary air supplied to the intake system of the internal combustion engine based on a detection signal from an exhaust sensor installed in the exhaust system of the internal combustion engine.
In the secondary air supply device, for a predetermined period of time from the start of operation of the EGR valve that adjusts the amount of exhaust gas recirculated to the intake system of the internal combustion engine, secondary air is supplied to the intake system of the internal combustion engine according to the detection signal of the exhaust sensor. An intake secondary air supply device for an internal combustion engine, comprising a control means for suspending supply control.