JP3205366B2 - Secondary air supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exhaust system for an engine.
The present invention relates to improvement of a secondary air supply device for supplying secondary air, and particularly to measures for improving exhaust gas purification performance.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Utility Model Laid-Open Publication No.
As disclosed in Japanese Patent Application Publication No. 15-315, a three-way catalyst and an oxidation catalyst are arranged on the upstream side and the downstream side, respectively, along the exhaust gas flow in the exhaust passage, and the first catalyst is provided on the upstream side of the three-way catalyst. A secondary air inlet is provided, and a second secondary air inlet is provided in a space between the oxidation catalyst and the three-way catalyst, that is, immediately upstream of the oxidation catalyst, and the first secondary air inlet is provided when the engine is cold. It is known that secondary air is introduced from an air inlet while secondary air is introduced from a second secondary air inlet after engine warm-up is completed.

[0003]

However, when the secondary air inlet is provided upstream of the catalyst device as described above, the secondary air is introduced by an electric air pump.
In this case , the electric air
Since the supply amount of the secondary air is unstable due to the start of the pump from the stop state and becomes the desired amount only after a lapse of a predetermined time thereafter, the unburned component of the fuel at the start of the introduction There is a regret that the desired exhaust gas purification performance of the catalyst device cannot be obtained at the start of the introduction of the secondary air as a result.

[0004] The present invention has been made in view of such a point, and an object thereof is to provide a secondary air pump using an electric air pump.
When the introduction of secondary air is started, even if the initial supply amount of secondary air cannot be controlled to a desired amount at the start of secondary air introduction, the desired purification performance of the catalyst device is ensured. Another object of the present invention is to improve exhaust gas purification performance.

[0005]

In order to achieve the above object, according to the present invention, at the beginning of the introduction of the secondary air, the secondary air at the beginning of the introduction is supplied to the upstream side exhaust gas having a high exhaust temperature without depending on the catalyst device. By supplying the air to the passage, the unburned components are satisfactorily burned even when the secondary air is initially introduced, and then supplied to the catalyst device only when the amount of the introduced secondary air is stabilized, and the exhaust gas is exhausted. Purification performance will be secured as expected .

That is, as shown in FIG. 1, a specific solution of the invention according to the first aspect is that the upstream side and the downstream side of the catalyst device 20 disposed in the exhaust passage 6 are arranged along the exhaust gas flow. Two secondary air inlets 35a, 36a on the side
And the secondary air inlets on the upstream and downstream sides
An electric air pump 33 for introducing air is provided . The secondary air engine operating condition is to be supplied with secondary air
A detecting means 65 for detecting when entering the feed zone, receives the output of the detection means 65, the engine operating condition is the 2 Tsugisora
When the secondary air entering the air supply region shifts from the non-introduced state to the introduced state, the electric air pump 33 is turned on by the voltage non-injection.
Control from the applied state to the applied state,
A control means 66 is provided for introducing secondary air into the exhaust passage 6 from the secondary air inlet 35a and then introducing secondary air into the exhaust passage 6 from the downstream secondary air inlet 36a after a lapse of a set time. Configuration.

In the invention according to claim 2, the control means 66 according to claim 1 is specified, and the control means 66 is limited to a method in which secondary air is introduced into the exhaust passage in an acceleration state in which fuel is increased.

Further, according to the invention described in claim 3, according to claim 1,
Alternatively, the invention according to claim 2 is further limited, and two catalyst devices, an upstream side and a downstream side, are arranged along the exhaust gas flow with respect to the exhaust passage, and the upstream side catalyst device is disposed immediately upstream of the upstream side catalyst device. A secondary air inlet 35a is provided, and a downstream secondary air inlet 36a is provided immediately upstream of the downstream catalyst device.

[0009]

According to the above-mentioned structure, according to the first aspect of the present invention,
In the initial stage of the introduction of the secondary air when the electric air pump 33 starts to start, the supply amount of the secondary air introduced at the beginning is unstable.
However , since the secondary air is introduced into the exhaust passage 6 from the secondary air inlet 35a on the upstream side, the secondary air is supplied to the exhaust gas having a high temperature, and the fuel existing in the exhaust gas is supplied. Unburned components burn well.

Then, when the set time elapses and the secondary air amount is stabilized, secondary air is introduced from the secondary air inlet 36a on the downstream side closer to the catalyst device 20, so that the catalyst is The amount of unburned components of the fuel and the required amount of secondary air in the device 20 correspond favorably, and the exhaust gas purification performance in the catalyst device 20 is exhibited as expected . As a result, the combustion of the unburned components due to the introduction of the secondary air upstream of the exhaust passage in the early stage of the secondary air introduction and the desired exhaust gas purifying action of the catalyst device 20 after the introduction thereof are combined, and As a result, the exhaust purification performance is effectively improved.

In this case, in the accelerated state, although the amount of unburned components increases by an amount corresponding to the increase in the amount of fuel, the control means 66 of the first aspect operates in this accelerated state. Therefore, even in this accelerated state, the exhaust gas purification performance is favorably exhibited.

According to the third aspect of the invention, at the beginning of the introduction of the secondary air, although the ambient temperature of the catalyst device is relatively low, the secondary air is not introduced from the secondary air inlet 35a on the upstream side. Since the fuel component is satisfactorily burned, the temperature of the upstream catalytic device is increased and activated, and the exhaust gas purifying performance of the upstream catalytic device is favorably exhibited. Further, after a lapse of a set time from the beginning of the introduction, the exhaust gas temperature is maintained high by the combustion of the unburned components on the upstream side, and the temperature of the downstream catalytic device is also correspondingly high. In this state, when the secondary air is introduced from the secondary air inlet 36a on the downstream side, the exhaust purification performance of the downstream catalytic device is properly exhibited as expected.

[0013]

As described above, according to claim 1,
According to the secondary air supply device, when the electric air pump is started,
In the early stage of the introduction when the supply amount of the secondary air is unstable, the secondary supply amount is stabilized after the secondary air is introduced into the exhaust passage on the upstream side where the exhaust temperature is high to satisfactorily burn the unburned components. It is only at the stage where the secondary air inlet near the downstream catalytic device is
By introducing the secondary air, the amount of unburned
Because the amount of secondary air is made to correspond favorably, the combustion of unburned components upstream of the exhaust passage and the desired purification performance of the catalytic device can be secured, and the exhaust purification performance can be effectively improved. .

In particular, according to the second aspect of the present invention, even in an accelerated state in which the fuel is increased, the combustion of unburned components upstream of the exhaust passage and the desired purification performance of the catalytic converter are ensured. As a result, the exhaust gas purification performance can be effectively improved.

Further, according to the third aspect of the invention, in the initial stage of introduction, secondary air is introduced upstream of the exhaust passage to activate the upstream catalytic device by burning unburned components,
After the amount of secondary air is stabilized and the temperature of the catalyst catalyst on the downstream side is stabilized by the combustion of the unburned components, secondary air is introduced from the secondary air inlet on the downstream side, and exhaust gas is purified by the catalytic device on the downstream side. Since the performance has been secured as expected, the exhaust purification performance can be more effectively enhanced.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 2, reference numeral 1 denotes a V-type engine, and left and right banks 1a and 1b are provided with combustion chambers 4 having variable volumes formed by pistons 3 inserted into cylinders 2 inclined at a predetermined angle. Have been. Each of the combustion chambers 4 is communicated with the atmosphere via independent intake passages 5a and 5b and one collective intake passage 5c where the two passages are joined at the upstream end thereof, and has independent exhaust passages 6a. , 6b and the respective exhaust passages are collectively opened to the atmosphere through a collective exhaust passage 6c. An air cleaner 10 is arranged at an upstream end of the collective intake passage 5c, a throttle valve 12 for adjusting an intake air amount is arranged on the way, and a negative pressure chamber 11 is arranged at a downstream end. At the downstream ends of the independent intake passages 5a and 5b, fuel injection valves 18 for injecting and supplying fuel are arranged, respectively.

The independent exhaust passages 6a, 6b are directly connected to the catalyst devices 7, 7 at a portion immediately downstream of the exhaust ports, and the collective exhaust passage 6c is connected to the catalyst devices 20 in order from the upstream.
And an exhaust silencer 21 are provided. A secondary air inlet 35a, 35a on the upstream side is opened immediately upstream of the catalyst device 7, 7 in each of the independent exhaust passages 6a, 6b, and downstream just upstream of the catalyst device 20 in the collective exhaust passage 6c. Side 2
The secondary air inlet 36a is open, and the two secondary air inlets 35a and 36a constitute two secondary air inlets provided along the exhaust flow.

A fuel tank 25 has a fuel pipe 3 in which a filter 26, a fuel pump 27, and a fuel filter 28 are disposed.
0 upstream end is located. A downstream side of the fuel filter 28 of the fuel pipe 30 is connected to the fuel injection valve 18, and a pressure regulator 31 and a solenoid valve 32 for controlling the pressure regulator 31 are disposed further downstream of the fuel injection valve 18. Is returned to the fuel tank 25 through the return pipe 31a.

In addition, 33 is an electric type for supplying secondary air.
Air pump (hereinafter, referred to as an electric pump) an air suction side of the electric pump 33 through the suction passage 34 communicates with the air cleaner 10 immediately downstream of the collection intake passage 5c, the air discharge side 2 branched One of them is further branched into two via the air supply passage 35, and then communicates with the upstream secondary air introduction ports 35a, 35a opened immediately upstream of the catalyst devices 7, 7 at the upstream ends of the independent exhaust passages 6a, 6b, respectively. The other air supply passage 36 communicates with a downstream secondary air introduction port 36a which is open immediately upstream of the catalyst device 20 in the collective exhaust passage 6c.

In the middle of the two air supply passages 35, 36, on-off valves 37, 38 for opening and closing the respective passages 35, 36 are provided.
And on-off valves 37, 38.
The solenoid valves SOL1 and SOL2 are connected to the solenoid valves SOL1 and SOL2, respectively. When the solenoid valves SOL1 and SOL2 are turned ON, the negative pressure of the negative pressure passages 39a and 39b communicating with the negative pressure chamber 11 is introduced to the corresponding on-off valves 37 and 38, respectively. Then, the opening / closing valves 37 and 38 are opened.

Reference numeral 41 denotes a canister. The canister 41 collects the fuel vapor in the fuel tank 25. The collected fuel passes through a purge control valve 42 and a purge passage 43, and is a throttle valve in the collective intake passage 5c. 12 downstream. In the figure, 44 is a resonator, and 45 is an EGR control valve.

In addition, 51 is an air flow sensor for detecting the amount of intake air, 52 is an intake air temperature sensor disposed immediately downstream of the air cleaner 10, 53 is an opening sensor for detecting the opening of the throttle valve 12, and 54 and 55. Is the left and right bank 1
a, 1b, a vibration sensor for detecting engine vibration; 56, a cooling water temperature sensor; 57, a cold start water temperature switch;
a, O ₂ sensor for detecting the air-fuel ratio of the mixture is placed 5b, 59 is a crank angle sensor for detecting an engine rotational speed by the crank angle of the engine 1.

The above-mentioned sensors and switches 51 to 51
The signal 59 is output from the controller 6 having a CPU and the like inside.
1 is input. The controller 61 controls the opening and closing of the two on-off valves 37 and 38 by controlling the electric pump 33 and the two solenoid valves SOL1 and SOL2,
The secondary air is supplied to the upstream and downstream secondary air inlets 35a,
36a, the independent exhaust passage 6a of the exhaust system of the engine 1
6b and collective exhaust passage 6c.

Next, the control of the electric pump 33 and the two on-off valves 37 and 38 by the controller 61 will be described with reference to the control flow of FIG. In the figure, after starting, in step S1, the intake air amount Qa from the air flow sensor 51 and the engine speed Ne from the crank angle sensor 59 are read, and in step S2, the read intake air amount Qa is calculated. Difference Qan-Q between previous value and current value
The an,-1 determines whether or not the setting value alpha or equivalent at a predetermined acceleration, when a predetermined following non accelerated Qan -Qan-1 ≦ α,
That is, in the steady state , the correction coefficient C for increasing the acceleration in step S3.
While acc is set to Cacc = 1, Qan-Qan-
At the time of acceleration equal to or greater than a predetermined value of 1> α, the degree of acceleration Qan-Qan-
The acceleration increase correction coefficient Cacc is read according to 1.

Thereafter, the fuel injection pulse width Tp output to the fuel injection valve 18 in step S5 is changed to the basic pulse width τe,
Acceleration increase correction coefficient Cacc and other total correction coefficient Ct
The fuel injection pulse width Tp is output to the fuel injection valve 18 in step S6, and the second order shown in FIG. 4 is determined based on the read intake air amount Qa and engine speed Ne in step S7. It is determined whether or not the area is an air supply area.

If it is determined in step S8 that the air is in the secondary air supply region, the voltage applied to the electric pump 33 in accordance with the intake air amount Qa and the engine speed Ne at that time is set in step S9. In step S10, the value of the flag F indicating the initial stage of the introduction of the secondary air is determined.
Therefore, in step S11, the timer T is set to the initial value T1 as the elapsed time from the initial stage of introduction. This timer value T1 corresponds to the time from when the electric pump 33 is started to when the air discharge amount is stabilized. Then, step S1
2, the catalysts 7, 7 arranged in the independent exhaust passages 6a, 6b
In order to introduce the secondary air from the secondary air inlet 35a on the immediately upstream side, the solenoid valve SOL1 is turned on, the opening and closing valve 37 is controlled to open, and the air introduction passage 35 is opened. After that, the flag F is set to 1 in step S13, and the process returns.

Thereafter, since F = 1 in step S10, the value of the timer T is determined in step S14. If the set time of T ≠ 0 has not elapsed, step S10 is executed.
At 15, the timer value T is subtracted, and the introduction of the secondary air from the secondary air inlet 35a on the upstream side is continued.
In step S16, the solenoid valve SOL2 is turned on and the on-off valve 38 is controlled to open in order to introduce secondary air from the secondary air inlet 36a immediately upstream of the catalyst catalyst 20 disposed in the collective exhaust passage 6c. , The air introduction passage 36 is opened, and the solenoid valve SOL1 is turned off in step S17, and the on-off valve 37 is opened.
Is closed, the air introduction passage 35 is closed, and the introduction of secondary air from the secondary air introduction port 35a on the upstream side is stopped. After that, the flag F is returned to 0 in step S18, and the process returns.

Therefore, in the control flow of FIG.
According to steps S7 and S8, the engine operating state is
The detection means 65 for detecting when the secondary air should be supplied , which has entered the secondary air supply area shown in FIG.

Steps S1 to S6 and S9 to S
The 18, in the steady state and the acceleration state of the engine 1, when the engine operating condition has entered the secondary air supply region in FIG. 4, i.e. at the transition to the introduction state from untransfected state of the secondary air, the electric pump 33 Start applying voltage V to
Controls the electric pump 33 from the voltage non-applied state to the applied state
At the same time, the air supply passage 3
5, the secondary air is introduced into the independent exhaust passages 6a, 6b immediately upstream of the catalyst devices 7, 7 from the secondary air inlet 35a on the upstream side, and when the set time T of the timer elapses, The opening / closing valve 38 is opened from the secondary air inlet 36a on the downstream side to allow the secondary air to flow through the catalyst device 20 in the collective exhaust passage 6c.
The control means 66 is configured to be introduced immediately upstream of the control means.

[0031] Thus, in the above embodiment, when the engine operating state shifts to the secondary air supply region shown in FIG. 4, as shown in FIG. 5, an engine operating the electric pump 33 that has been stopped until then Although the voltage V corresponding to the state is applied to start the electric pump 33, the air discharge is unstable. However, during the unstable set time T1, the secondary air from the electric pump 33 passes through the air supply passage 35 to introduce the secondary air on the upstream side by the opening operation of the on-off valve 37 by the ON control of the solenoid valve SOL1. Mouth 3
Since the secondary air is supplied from 5a and 35a to the independent exhaust passages 6a and 6b immediately upstream of the catalyst devices 7 and 7, the secondary air satisfactorily reacts with the unburned components in the high-temperature exhaust gas, and the exhaust gas is satisfactorily exhausted. Be purified.

Further, after the lapse of the set time T1 after the start, the secondary air discharge amount of the electric pump 33 is in a stable state.
Instead of the supply of the secondary air from 5a, the secondary air from the electric pump 33 is introduced into the downstream side through the air supply passage 36 by the opening operation of the on-off valve 38 by the ON control of the solenoid valve SOL2. Since the air is supplied from the ports 36a, 36a to the upstream of the catalyst device 20 in the collective exhaust passage 6c, the amount of secondary air in the catalyst device 20 and the amount of unburned fuel components correspond well, and the catalyst device 20 Exhaust gas purifying action is exhibited as expected. Accordingly, the exhaust gas purification in the independent exhaust passages 6a and 6b when the secondary air supply amount of the electric pump 33 is unstable, and the desired exhaust gas purification action of the catalyst device 20 in the stable state after the set time T1. As a result, the exhaust gas purification performance can be effectively improved.

In particular, the supply of the secondary air to the exhaust gas upstream side when the supply amount is unstable and the supply of the secondary air to the upstream side immediately upstream of the catalyst device 20 when the supply amount is stable thereafter are supplied to the engine 1. As described above, even when the amount of unburned components of the fuel is large, the exhaust gas purification performance can be effectively improved as described above.

Further, when the secondary air from the electric pump 33 is started, the secondary air introduction port 35a,
The exhaust gas 35a is supplied to the independent exhaust passages 6a, 6b immediately upstream of the catalyst devices 7, 7 in the independent exhaust passages 6a, 6b and reacts with the unburned components in the high-temperature exhaust gas. Therefore, even if the temperature of the catalyst devices 7 and 7 is low, the temperature rises and reaches near the activation temperature, and the exhaust gas purification performance is improved. Moreover, the independent exhaust passages 6a, 6
Since the temperature of the catalyst device 20 disposed in the collective exhaust passage 6c rises and approaches the activation temperature due to the combustion of the unburned components in b, the exhaust gas purifying action in the catalyst device 20 is performed stably. Exhaust gas purification performance will be exhibited effectively as expected.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the invention described in claim 1;

FIG. 2 is a diagram showing an overall configuration.

FIG. 3 is a flowchart illustrating control of a supply amount of secondary air to an engine exhaust system.

FIG. 4 is an explanatory diagram of a secondary air supply region.

FIG. 5 is an operation explanatory view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine 6a, 6b Independent exhaust passage 6c Collective exhaust passage 7, 20 Catalyst device 33 Electric pump (electric air pump) 35, 36 Air supply passage 35a Secondary air inlet 36a on the upstream side Secondary air inlet 36a on the downstream side SOL1 , SOL2 Solenoid valve 37, 38 On-off valve 61 Controller 65 Detection means 66 Control means

Continuation of front page (72) Inventor Hisashi Zamanashi 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (56) References JP-A-49-111024 (JP, A) JP-A-62-103459 ( JP, A) JP-A-52-50414 (JP, A) JP-A-1-249916 (JP, A) Full-open 1979-176427 (JP, U) Full-open 1979-53118 (JP, U) Full-open 56-127813 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01N 3/22 F01N 3/32

Claims (3)

(57) [Claims] Upstream of claim 1 the catalyst device disposed in an exhaust passage, with two of the secondary air inlet on the upstream side and the downstream side is provided along the exhaust gas flow, the secondary of the upstream and downstream Guides secondary air to the air inlet
Electric air pump to be turned on and secondary air supply for engine operation to supply secondary air
Detecting means for detecting when entering the area, receives the output of the detection means, second engine operating condition is the
When the secondary air entering the air supply area shifts from the non-introduced state to the introduced state, the electric air pump does not apply a voltage.
Controls the application state from the state after introducing the secondary air into the exhaust passage from the secondary air inlet of the upstream side exhaust passage secondary air from the secondary air inlet of the downstream side after the setting time has elapsed And a control means for introducing the air into the secondary air supply device. 2. The secondary air supply device according to claim 1, wherein the control means introduces secondary air into the exhaust passage in an acceleration state in which fuel is increased. 3. An exhaust passage is provided with two upstream and downstream catalytic devices along the exhaust flow, and an upstream secondary air inlet is provided immediately upstream of the upstream catalytic device. 3. The secondary air supply device according to claim 1, wherein a downstream secondary air inlet is provided immediately upstream of the downstream catalyst device.