JP3446250B2 - Engine secondary air supply device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary air supply system for an engine for purifying unburned gas such as hydrocarbon HC contained in exhaust gas discharged from the engine.

[0002]

2. Description of the Related Art Generally, carbon monoxide CO and hydrocarbon H which are harmful components are contained in exhaust gas discharged from an engine.
It contains unburned gas such as C. Therefore, JP-A-59
As described in JP-A-138714, a secondary air supply device for supplying secondary air is provided in the middle of an exhaust passage for exhausting exhaust gas from an engine to the atmosphere, and the secondary air is supplied by the secondary air. It has been proposed to promote the oxidation of the fuel gas and the reaction of the catalyst provided downstream of the exhaust passage to purify the unburned gas more reliably.

When the amount of secondary air supplied to the exhaust passage is smaller than that of exhaust gas, the oxidizing action of the unburned gas by the secondary air and the action of promoting the reaction of the catalyst are reduced. Further, when the supply amount of the secondary air becomes excessive as compared with the exhaust gas, the excess secondary air supercools the catalyst and the reaction of the catalyst deteriorates.

Therefore, it is necessary to control the supply amount of secondary air in accordance with the exhaust gas amount. For example, when the engine speed increases and the exhaust gas amount increases, a large amount of secondary air is supplied accordingly, while the engine speed decreases and the exhaust gas amount decreases as during deceleration. At times, the supply amount of secondary air is reduced accordingly.

[0005]

However, there is a certain response delay in the change in the supply amount of the secondary air due to the change in the supply of the secondary air according to the change in the exhaust gas amount. In particular, when decelerating and re-accelerating in a short time, a considerable response delay occurs until the supply amount of secondary air, which has been changing in the decreasing direction, increases to an extent commensurate with the increase in the exhaust gas amount, resulting in unburned gas. Deteriorating ability of.

Further, for example, when the vehicle is decelerated from a high load state, immediately after the deceleration, the fuel adhering to the intake passage of the engine and the inner wall of the combustion chamber is released and burns at the time of high load, so that the unexposed gas in the exhaust gas is Since the fuel gas is likely to increase, if the supply amount of the secondary air is reduced at the same time as the deceleration, the secondary air is likely to be insufficient immediately after the deceleration.

In view of the above circumstances, the present invention is directed to an engine capable of reliably purifying unburned gas even during deceleration and preventing deterioration of unburned gas purifying performance due to reacceleration immediately after deceleration. An object is to provide a secondary air supply device.

[0008]

The invention according to claim 1 is
An exhaust gas amount for detecting data relating to the exhaust gas amount in a secondary air supply device of an engine having a secondary air supply means for supplying secondary air in the middle of an exhaust passage for exhausting exhaust gas from the engine to the atmosphere The smaller the exhaust gas amount detected by the detection means and the exhaust gas amount detection means,
Secondary air amount setting means for setting the required supply amount of the secondary air to a small amount, and the supply amount of the secondary air to be the required supply amount of the secondary air set by the secondary air amount setting means. Supply control means for controlling the secondary air supply means, deceleration detection means for detecting deceleration of the engine, and reduction of the supply amount of the secondary air during deceleration of the engine according to the detection result of the deceleration detection means. and delay means for delaying the en
Engine rotation speed detection means for detecting the rotation speed of the gin, and
Depending on the detection result of the engine speed detection means of
The lower the engine speed when decelerating the gin, the more the delay
Reduce the delay time for the reduction of the secondary air supply amount due to the step
And a delay time setting means for setting .

[0009]

The invention according to claim 2 is an engine?
Secondary exhaust in the middle of the exhaust passage that exhausts these exhaust gases to the atmosphere.
Secondary of engine having secondary air supply means for supplying
Data related to the amount of exhaust gas in the air supply device
Exhaust gas amount detection means to detect and this exhaust gas amount detection hand
The smaller the amount of exhaust gas detected by the stage, the more secondary air
Secondary air amount setting means to set the required supply amount to a small amount
And the secondary air supply amount is set by the secondary air amount setting means.
The secondary air so that the required secondary air supply amount set by
Supply control means for controlling the next air supply means and the engine
Deceleration detection means for detecting the time of deceleration, and the deceleration detection means
Depending on the detection result, the secondary air is decelerated when the engine decelerates.
Means for delaying the decrease in the supply amount of the engine , at least a supply amount storage means for storing the supply amount of the secondary air immediately before the deceleration of the engine , and at a time immediately before the deceleration of the engine according to the storage of the supply amount storage means. the more the supply amount of the secondary air, even with a delay time setting means for setting a short delay time of the reduction in the supply amount of the secondary air by said delay means
Of.

[0011]

[0012]

[0013]

According to the above construction, the data related to the exhaust gas amount is detected, and when the exhaust gas amount is small such as when the engine speed is low, the required supply amount of the secondary air is set to a small amount. The amount of secondary air supplied to the exhaust passage is controlled to be the required amount of secondary air supplied. When the engine speed decreases due to the engine deceleration, the secondary air supply amount decreases, but it is detected whether the engine is decelerating or not, and the secondary air supply amount decreases when the engine decelerates. Due to the delay, the secondary air supply amount does not decrease when the vehicle is re-accelerated in a short time immediately after deceleration.

Further, since the engine speed is detected, and the lower the engine speed during deceleration of the engine, the shorter the delay time for reducing the supply amount of the secondary air is set.
When the engine speed is low and the exhaust gas amount is small,
In response to this, the amount of secondary air supplied is reduced more rapidly, and supercooling of the catalyst due to excessive supply of secondary air is prevented.

Further, at least the supply amount of the secondary air immediately before the deceleration of the engine is stored, and the larger the supply amount of the secondary air immediately before the deceleration of the engine, the shorter the delay time for the decrease of the supply amount of the secondary air is set. By doing so, when the supply amount of the secondary air immediately before the deceleration of the engine is large, the supply amount of the secondary air is reduced accordingly, and supercooling of the catalyst due to excessive supply of the secondary air is prevented.

[0016]

[0017]

[0018]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an embodiment of an engine equipped with a secondary air supply device according to the present invention. The engine 1 is a cylinder head 1 that forms an upper part of a combustion chamber of each cylinder and is provided with a valve mechanism, an intake port, an exhaust port, and the like.
1, a cylinder block 12 in which cylinders for accommodating pistons are arranged, and an oil pan 13 for storing lubricating oil.

An exhaust passage 2 for discharging exhaust gas to the atmosphere is connected to the exhaust port of the cylinder head 11. A sub-catalyst 3 is arranged in the branch of the exhaust passage 2 to each cylinder, and a main catalyst 4 is arranged downstream of the merging position of the branch. The sub-catalyst 3 and the main catalyst 4 are for removing unburned gas such as carbon monoxide CO and hydrocarbon HC and NOX which are harmful components contained in the exhaust gas by oxidizing or reducing them.

A secondary air supply passage 5 is connected to the upstream side of the main catalyst 4 in the middle of the exhaust passage 2, and secondary air is supplied to the exhaust passage 2 through the secondary air supply passage 5. The secondary air supply means 6 is connected. The secondary air supply unit 6 is controlled by the secondary air control unit 14.

The secondary air supply means 6 comprises an air pump 7, a solenoid 8, a cut valve 9 and a check valve 10. The secondary air supply means 6 is the engine 1
When the purifying action of the unburned gas by the auxiliary catalyst 3 and the main catalyst 4 is lowered as in the cold state, the secondary air is supplied to the exhaust passage 2 to oxidize the unburned gas and the auxiliary catalyst 3 and the main catalyst 4 It promotes the reaction of unburned gas.

The air pump 7 is composed of an electric brushless motor or the like, and supplies outside air to the exhaust passage 2 as secondary air. The solenoid 8 drives the cut valve 9 according to a control signal from the secondary air control unit 14. The cut valve 9 opens and closes the supply of secondary air from the air pump 7 to the secondary air supply passage 5 in response to the driving of the solenoid 8. The check valve 10 prevents backflow of exhaust gas from the exhaust passage 2 to the cut valve 9 side.

The secondary air control unit 14 includes the engine 1
Output signals from a water temperature sensor 15 for detecting the temperature of the engine cooling water in the water jacket, a throttle valve sensor 16 for detecting the opening of the throttle valve, an engine speed sensor 17 for detecting the engine speed, etc. are input. It has become so.

The secondary air control unit 14 is shown in FIG.
As shown in FIG. 2, the exhaust gas amount detecting means 140, the secondary air amount setting means 141, the supply control means 142, and the deceleration detecting means 1
43, a delay unit 144, and a supply amount storage unit 145.

The exhaust gas amount detecting means 140 examines the data relating to the exhaust gas amount, and determines the engine load obtained according to, for example, the throttle opening detected by the throttle valve sensor 16 and the engine speed sensor 1.
The operating state is checked by the engine speed detected by 7. The secondary air amount setting means 141 is
It sets the required supply amount of secondary air according to the amount of exhaust gas examined above, and the required supply amount of secondary air with the engine load and engine speed that are data related to the amount of exhaust gas as parameters. The map (FIG. 3) of FIG. The map of FIG. 3 is divided into three zones A, B, and C, and the required supply amounts Qa, Qb,
Qc has a relationship of Qa <Qb <Qc. The map of FIG. 3 is set so that the required supply amount of secondary air increases as the load and rotation speed increase, that is, as the amount of exhaust gas increases.

The supply control means 142 determines that the engine 1 is cold when the engine cooling water becomes 60 ° C. or less based on the detection result of the water temperature sensor 15, controls the solenoid 8 and controls the cut valve 9. Is opened and the secondary air is supplied to the exhaust passage 2. Further, the supply control means 142 controls the secondary air to be in the exhaust passage 2 at the required supply quantity of the secondary air set by the secondary air quantity setting means 141.
The air pump 7 is controlled to be supplied to the air pump 7. The deceleration detecting means 143 detects the time of deceleration of the engine 1 from the decrease in the engine speed detected by the engine speed sensor 17.

The delay means 144 is based on the detection result of the engine speed sensor 17 when the engine 1 is decelerated, that is, when the engine speed decreases and the required supply amount of secondary air decreases. The value of the timer corresponding to the engine speed is read and the supply amount storage means 145
The amount of secondary air supplied immediately before deceleration is calculated based on the stored contents of the above and the detection result of the engine speed sensor 17, and the value of the timer corresponding to the amount of secondary air supply immediately before deceleration is read from the map of FIG. It is a thing. Then, the deceleration detecting means 14
3 delays the decrease of the secondary air supply amount during deceleration according to the value of the timer.

The value of the timer in FIG. 4 is set to increase as the engine speed increases. this is,
The lower the engine speed, the smaller the amount of intake air and the amount of exhaust gas. In this case, the delay time is shortened to prevent the auxiliary catalyst 3 and the main catalyst 4 from being overcooled by the secondary air. This is because.

The timer value in FIG. 5 is set to be smaller as the supply amount of the secondary air before deceleration increases. This is because as the amount of secondary air supplied before deceleration increases, the amount of secondary air supplied tends to become excessive during deceleration, so the delay time is shortened and the auxiliary catalyst 3 and the main catalyst 4 are cooled by the secondary air. This is to prevent overdoing.

The supply amount storage means 145 stores at least the supply amount of secondary air immediately before deceleration of the engine 1.

Next, the secondary air supply control operation will be described with reference to the flowchart of FIG. Note that the timer value is reset to 0 in the initial state.

First, various signals such as the opening of the throttle valve, the engine speed, the water temperature of the engine cooling water, etc. are read (step S1). Next, it is determined whether the engine 1 is cold (step S2).

Then, for example, in a cold state where the water temperature of the engine cooling water becomes 60 ° C. or lower (Y in step S2).
ES), the oxidation and reduction reactions of the unburned gas of the auxiliary catalyst 3 and the main catalyst 4 become insufficient, so that in order to supply the secondary air, FIG.
The required supply amount of the secondary air according to the engine load and the engine speed is read from the map of (step S
3). Then, the solenoid 8 is driven, the cut valve 9 is closed, and the air pump 7 is further driven (step S4).

Next, whether or not the engine 1 is currently decelerating is determined by whether or not the engine speed has decreased (step S5). If the engine 1 is currently decelerating (YES in step S5), It is determined whether or not the vehicle was in the deceleration state at the time of the previous processing, that is, whether or not the current time point is the deceleration start time point (step S6).

If the deceleration is currently started (YES in step S6), the value of the timer corresponding to the engine speed is read from the map of FIG. 4, and the secondary value immediately before deceleration is read from the map of FIG. The value of the timer corresponding to the air supply amount is read (step S7).

On the other hand, in the deceleration state from the time of the previous processing, that is, when the present time is already decelerating (NO in step S6), the value of the timer in the previous processing is maintained as it is, and the process proceeds to step S8.

In step S8, it is determined whether or not the timer has timed out, that is, whether or not the value of the timer has become 0. If the time has not expired (YES in step S8), the value of the timer is decremented. Then, the required supply amount of the secondary air immediately before deceleration is read from the supply amount storing means 145 (step S10), and the required supply amount of the secondary air matches the required supply amount of the secondary air. The air pump 7 is drive-controlled as described above (step S11). After that, the process returns to step S1 and the processes after step S1 are repeated.

On the other hand, if the present time is acceleration or constant speed operation (NO in step S5), the supply amount of secondary air matches the required supply amount of secondary air read in step S3. The air pump 7 is drive-controlled (step S11).

On the other hand, if the water temperature of the engine cooling water rises in step S2 and exceeds 60 ° C. (NO in step S2), the temperature of the exhaust gas rises and unburned by the auxiliary catalyst 3 and the main catalyst 4. Since the gas can be completely removed, the solenoid 8 is driven to close the cut valve 9 and the air pump 7 is stopped (steps S12 and S1).
3). Then, the process returns to step S1.

The operation of the secondary air supply device will be described below.

When the engine 1 is re-accelerated in a short time immediately after deceleration, due to the response delay of the secondary air supply by the secondary air supply means 6 and the inertia of each mechanism of the secondary air supply means 6 during this acceleration. As shown by the alternate long and short dash line in FIG. 7, the supply amount of the secondary air rises much later than the increase in the engine speed. However, as shown by the solid line in FIG. Since the decrease in the required supply amount of secondary air in accordance with the decrease in engine speed is delayed, the supply amount of secondary air does not fluctuate during the transition from deceleration to acceleration in a short time. It is possible to avoid insufficient supply of secondary air and reliably purify unburned gas.

When the deceleration is performed, the fuel adhering to the inner wall of the combustion chamber of the engine 1 burns immediately after the deceleration, and thus the decrease in the unburned gas amount in the exhaust gas is delayed, but the secondary air By delaying the decrease in the required supply amount, the secondary air can be supplied according to the decrease in the unburned gas amount in the exhaust gas.

Although the map of the required supply amount of secondary air in FIG. 3 has the engine speed and the engine load as parameters, the required supply amount of the secondary air has only one of the engine speed and the engine load as a parameter. May be set.

[0044]

The present invention detects data relating to the amount of exhaust gas, and when the amount of exhaust gas is small, sets the required supply amount of secondary air to be small and also detects when the engine is decelerating. During the engine deceleration, the decrease of the secondary air supply amount is delayed, so the response delay of the secondary air supply control when re-accelerating in a short time after deceleration and the secondary air due to the inertia of the secondary air supply means. It is possible to avoid the shortage of supply of the fuel and to purify the unburned gas more reliably. In addition, it is possible to prevent a shortage of secondary air at the start of deceleration due to a delay in the decrease in the amount of unburned gas in the exhaust gas immediately after deceleration, and it is possible to reliably purify unburned gas even during deceleration. it can.

Further, the engine speed is detected, and the lower the engine speed during deceleration of the engine, the shorter the delay time for reducing the supply amount of the secondary air is set. When the amount of gas is small, the amount of supply of secondary air decreases faster accordingly, and it is possible to prevent overcooling of the catalyst due to excessive supply of secondary air, and to purify unburned gas more reliably. it can.

Further, at least the supply amount of the secondary air immediately before the deceleration of the engine is stored, and the larger the supply amount of the secondary air immediately before the deceleration of the engine, the shorter the delay time for the reduction of the supply amount of the secondary air is set. Therefore, when the amount of secondary air supplied immediately before the engine is decelerated is large, the amount of secondary air supplied will drop accordingly, and it is possible to prevent catalyst overcooling due to excessive secondary air supply. The unburned gas can be purified more reliably.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a secondary air supply device for an engine according to the present invention.

FIG. 2 is a block configuration diagram showing a configuration of a secondary air control unit.

FIG. 3 is a map showing a zone of a required supply amount of secondary air with an engine load and an engine speed as parameters.

FIG. 4 is a map showing a value of a timer corresponding to an engine speed.

FIG. 5 is a map showing a value of a timer corresponding to a supply amount of secondary air immediately before deceleration.

FIG. 6 is a flowchart showing a secondary air supply control operation.

FIG. 7 is a timing chart illustrating the operation of the present invention.

[Explanation of symbols]

1 engine 2 exhaust passage 3 auxiliary catalyst 4 Main catalyst 5 Secondary air supply passage 6 Secondary air supply means 7 Air pump 8 solenoids 9 cut valves 10 check valves 14 Secondary air control unit 15 Water temperature sensor 16 Throttle valve sensor 17 Engine speed sensor 140 Exhaust gas amount detection means 141 Secondary air amount setting means 142 Supply Control Means 143 Deceleration detection means 144 delay means 145 Supply amount storage means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI F02D 45/00 314 F02D 45/00 314F (56) References JP-A-52-109025 (JP, A) JP-A-63-36016 (JP, A) JP-A-55-87812 (JP, A) Actually developed 63-191228 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F01N 3/22 F01N 3 / 32 F02D 45/00

Claims (2)

(57) [Claims] 1. A secondary air supply device for an engine having secondary air supply means for supplying secondary air in the middle of an exhaust passage for exhausting exhaust gas from an engine to the atmosphere. An exhaust gas amount detecting means for detecting, a secondary air amount setting means for setting a required supply amount of secondary air to a smaller amount as the exhaust gas amount detected by the exhaust gas amount detecting means is smaller, and a secondary air amount. Supply control means for controlling the secondary air supply means so that the supply amount of the secondary air is the required supply quantity of the secondary air set by the secondary air amount setting means, and deceleration detection means for detecting the deceleration time of the engine. A delay means for delaying a decrease in the supply amount of the secondary air at the time of deceleration of the engine according to the detection result of the deceleration detection means, and an engine speed for detecting the engine speed.
The detection means and the detection result of this engine speed detection means
Accordingly, the engine speed during deceleration of the above engine is low
The decrease of the supply amount of the secondary air by the delay means
A secondary air supply device for an engine, comprising: delay time setting means for setting a short delay time . 2. Exhaust gas from an engine is exhausted to the atmosphere
Secondary air supply hand that supplies secondary air in the middle of the exhaust passage
Exhaust gas in a secondary air supply device of an engine with steps
Exhaust gas amount detecting means for detecting data related to gas amount
And the exhaust gas detected by this exhaust gas amount detection means
The smaller the amount, the smaller the required supply amount of secondary air will be set.
Secondary air amount setting means and the secondary air supply amount
Required supply of secondary air set by the secondary air amount setting means
Supply that controls the secondary air supply means so that the supply amount is achieved.
Control means and deceleration detecting means for detecting deceleration of the engine
According to the detection result of this deceleration detection means, the engine
Delays the decrease of the secondary air supply amount when decelerating
Extension means and at least the secondary
A supply amount storage means for storing the supply amount of
Just before deceleration of the engine according to the memory of the memory
The larger the amount of secondary air supplied, the more
At the time of delay to set a short delay time for the decrease of the supply amount of the next air
A secondary air supply device for an engine, comprising: