JPH086629B2 - Secondary air control device for engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a secondary air control device for an engine.

(Prior Art) Generally, in an internal combustion engine, it is not possible to take out all the heat energy generated in the cylinder as a shaft output, and a considerable part thereof is lost as various losses such as heat loss and mechanical loss, which results in fuel consumption. It is one of the obstacles to improvement. One of the mechanical losses is the pump loss in the intake and exhaust strokes, which is particularly large at low loads than at high loads, so that it is especially important for automobile engines that are frequently used in the middle and low load regions. However, this greatly hinders the improvement of fuel efficiency.

On the other hand, it is known that fuel efficiency can be improved by coordinating an engine with a small stroke volume in the same vehicle. This is because the engine performs relatively high load operation.
It is believed that one of the major reasons is that the pump loss is reduced. Therefore, if the engine is made to perform the same function as a small stroke volume engine only at low load, the pump loss at low load is reduced and fuel efficiency is improved without impairing the required characteristics at high output of the engine. It is considered possible.

That is, in order to reduce the pump loss at the time of low load, it is sufficient to reduce the throttle loss due to the suction negative pressure increase based on the small throttle valve opening degree at the intake stroke and the compression loss at the compression stroke at the time of the low load. . This applies not only to reciprocating piston type engines, but also to rotary piston engines,
As means for this purpose, in a rotary piston engine, for example, as described in Japanese Patent Laid-Open No. 505962/1975, intake air that leaks a part of intake air to the intake passage side during the compression stroke in addition to the intake passage A recirculation passage (bypass passage) is provided, an opening / closing control valve for output adjustment is arranged in the intake / recirculation passage, and the opening degree and closing timing of the opening / closing control valve are adjusted according to the load state of the engine. A first conventional technique is known in which the intake air recirculation amount is controlled in a controlled manner. That is, the first conventional technique includes an intake device for a rotary piston engine, an intake passage for supplying intake air from the atmosphere into the cylinder during an intake stroke of the engine,
An intake air recirculation passage that communicates the middle of the intake air passage with the cylinder to recirculate a part of the intake air in the cylinder to the intake passage side during a compression stroke of the engine, and an open / close control valve that opens and closes the intake air recirculation passage. It is configured to control the opening / closing state of the opening / closing control valve according to the operating region to adjust the intake air recirculation amount, thereby controlling the substantial intake air filling amount.

According to such an intake device for a rotary piston engine, the opening / closing control valve substantially functions as an effective compression ratio varying means of the engine, which reduces pump loss at low load, which results in a large fuel consumption. It is expected to improve.

On the other hand, in general, even in an engine having a variable compression ratio structure as described above, in order to purify the exhaust gas, fresh air is introduced into the exhaust port of the engine and the exhaust gas in the high temperature state is converted into oxygen gas. The unburned components (hydrocarbons, etc.) contained in the exhaust gas are mixed by contact mixing with abundant fresh air.
A secondary air supply device that burns and removes (oxidizes) carbon monoxide is usually provided.

When supplying such secondary air, simply
Purification of the exhaust gas by only supplying the secondary air does not always provide a sufficient purification action (for example, NOx cannot be treated). And other post-treatment devices such as a three-way catalytic converter (catalyst converter) are combined to form an efficient exhaust gas purification system (oxidation and reduction treatment system) centering on the secondary air supply device.

By the way, even when the exhaust gas purification system is configured by combining the catalytic converters in this way, the amount of the exhaust gas component supplied from the engine to the catalytic converter unit is
It necessarily varies depending on the operating state (rotation or load region) of the engine. Therefore, the supply state and the supply amount of the secondary air supplied by the secondary air supply device should originally be properly controlled according to the operating state of the engine.

From such a point of view, as the second conventional technique, it is possible to reduce the load on the catalytic converter depending on the operating state of the engine.
There is a secondary air control device that variably controls the supply state of secondary air (see, for example, Japanese Patent Publication No. 54-35251).

(Problems to be Solved by the Invention) By the way, in the case of the second conventional technique, the secondary air is supplied by an air pump constantly driven by the engine. Normally, the amount itself is adjusted by an air control valve that is controlled according to an operating region specified by the throttle opening and the engine speed.

However, as in the case of the second prior art, a pump for controlling the supply amount of secondary air to the exhaust gas purification device according to the operating region is provided by the variable effective compression ratio of the engine as in the first prior art. When applied to an engine equipped with loss reduction means, the following problems occur.

That is, since the effective compression ratio of the engine is reduced in the pump loss reduction region, the compression pressure in the combustion chamber is reduced, and therefore the compression temperature is also reduced.
As a result, the air-fuel mixture combustion speed decreases, the combustion state deteriorates, and the unburned gas in the high temperature state is directly discharged to the exhaust port and the catalytic converter side. Nevertheless, a large amount of secondary air, which is determined solely by the operating region, is supplied and comes into contact with the unburned gas, and the exhaust gas temperature is increased due to the rapid re-combustion of the unburned gas in that portion. There is a situation where the temperature rises abnormally and impairs the function of the three-way catalytic converter.

(Means for Solving Problems) The present invention has been made for the purpose of solving the above problems, and is a pump loss reducing means for substantially reducing pump loss by substantially shortening an intake stroke in a specific operating region. In the secondary air control device of the engine, the exhaust gas purification device, and the secondary air supply device for controlling the amount of secondary air supplied to the exhaust gas purification device corresponding to the operating region. The secondary air supply amount correcting means for reducing the amount of the secondary air supplied to the exhaust gas purification device at the time of the operation of the above is provided.

(Operation) According to the above means, in the pump loss reduction region where the intake stroke is substantially shortened, the original 2
The secondary air supply amount can be controlled so that the secondary air is supplied by a predetermined amount smaller than the secondary air supply amount.

Therefore, the effective compression ratio of the engine is substantially reduced by shortening the intake stroke, so that the secondary air supply amount itself is reduced even if the combustion speed is lowered and the exhaust gas becomes hot in consideration of the expansion stroke. As a result, the combustion reaction rate on the exhaust side decreases and the rise in temperature is suppressed within a predetermined range that does not impair the function of the exhaust gas purification device such as a catalytic converter. Absent.

(Embodiment) FIGS. 2 and 3 show an engine secondary air control apparatus according to an embodiment of the present invention applied to a rotary piston engine.

First, in FIG. 2, reference numeral 1 indicates, for example, a two-cylinder rotary piston engine main body, and this rotary piston engine main body (hereinafter referred to as engine main body) 1
As shown in Fig. 3, the trochoid space 2,
The two rotor housings 4 and 5 which form 3 and three side housings which are located on both sides of these two rotor housings 4 and 5 and close both side portions of the respective rotor housings 4 and 5 (common center portion). The side housing is specifically referred to as an intermediate housing) 6, 7, and 8. In the trochoid spaces 2 and 3 of the rotor housings 4 and 5, the trochoidal inner surfaces 4a and 5a inside the rotor housings 4 and 5 are inscribed around the eccentric shaft 9 by 180 degrees. Two substantially triangular rotors 10 and 11 which are planetary rotated with a phase difference of 10 are loosely fitted.

Three outer peripheral surfaces 10a to 10c, 11a to 11c of the rotors 10 and 11
And the inner peripheral surface 4a of the trochoid of the rotor housing 4,5,
Three working chambers 13A to 13C and 14A to 14C are provided between each of them and 5a.
Are formed. In addition, the above rotor housings 4,5
Exhaust ports 15, 16 are opened in the trochoid inner peripheral surfaces 4a, 5a corresponding to the lower part of one side of the exhaust port 15,
16 is commonly connected to an external exhaust pipe 19 through exhaust ports 17 and 18.

On the other hand, in the side housing located between the rotor housings 4 and 5 among the three side housings 6 to 8, that is, in the intermediate housing 7, two intake ports 21 and 22 communicating with the intake pipe 42 are provided. The openings are opened toward the working chambers in the trochoid spaces on the rotor housings 4 and 5 side. In addition, the intermediate housing has one side (front side) corresponding to the planet rotation having a 180-degree phase difference between the two rotors 10 and 11.
The compression stroke working chamber (13A to 13C) of the first rotor housing 4
The first communication state in which one of the two) communicates with the intake stroke working chamber (any of 14A to 14C) of the second rotor housing 5 on the other side (rear side), and the second side (rear side) on the other side. Second communication for communicating the compression stroke working chamber (any one of 14A to 14C) of the rotor housing 5 of one side with the intake stroke working chamber (one of 13A to 13C) of the one side (front side) first rotor housing 4 An intake air recirculation passage 25 is formed which alternately forms a state and a state. This intake air recirculation passage 25 can be easily provided by forming a through hole at a predetermined position of the intermediate housing 7 for allowing the trochoid spaces 2 and 3 to communicate with each other, as shown in FIG. A disc-shaped butterfly-type opening / closing control valve 26 is installed in the center of the intake air recirculation passage 25, and the opening / closing control valve 26 is controlled to be fully closed in the high speed and high load region. On the other hand, in the low speed and low load region, the valve is opened according to the load amount thereof, and the opening cross-sectional area of the intake air recirculation passage 25 is made variable to control the recirculation intake air amount.

The opening / closing control valve 26 is opened / closed by an opening / closing valve actuator 40 having a diaphragm structure which is driven according to an operating state (valve position) of a duty solenoid 41 which is controlled by an engine control unit 50 which will be described later. The state is specifically controlled.

On the other hand, the intake ports 21 and 22 are respectively communicated with the air cleaner 43 through the intake pipe 42, and in the middle of the intake pipe 42,
A surge tank 44 is formed, and an air flow meter 45 and a throttle valve 46 are installed in the intake passage between the air cleaner 43 and the surge tank 44. The intake air amount detection signal Q of the air flow meter 45 is input to the engine control unit 50. Further, a throttle opening sensor 47 is attached to the throttle valve 46, and the throttle opening detection signal θ of the throttle opening sensor 47 is also supplied to the engine control unit 50.
Is input to Reference numeral 49 is a fuel injector, which is provided in the intake pipe 42. In addition, code 3
0 and 31 are auxiliary intake ports.

Then, the engine control unit 50, the throttle valve opening θ detected by the throttle opening sensor 47, the engine speed N, the engine cooling water temperature
Each Tw is input and a predetermined calculation is performed to control the operating state of the duty solenoid 41. The duty solenoid 41, which is a three-way solenoid valve, connects the working chamber of the diaphragm-structured on-off valve actuator 40 to the atmosphere side P ₁ ,
Alternatively, the drive state (opening / closing of the valve) of the opening / closing valve actuator 40 is controlled by selectively communicating with either one of the intake pipe 42 side (negative pressure side) P ₂ .

On the other hand, in the vicinity of the upstream end of the exhaust passage of the exhaust pipe 19 for exhausting the exhaust gas from the engine body 1, the first contact converter 51 and a second contact converter located at a predetermined distance downstream of the first contact converter 51. And the catalytic converters 52 are provided respectively. Then, a first secondary air supply nozzle 53 for supplying port air to the exhaust ports 15 and 16 on the exhaust upstream side of the first and second catalytic converters 51 and 52.
However, the above first and second catalytic converters 51, 52 are also
A second secondary air supply nozzle 54 for supplying split air is fitted and disposed in the exhaust passage portion therebetween.

Further, reference numeral 55 indicates from the first and second secondary air supply nozzles 53, 54 to the exhaust ports 15, 16 and the first, second.
Is an air pump for supplying secondary air between the respective catalytic converters 51, 52 of the engine main body 1 via a pulley with an electromagnetic clutch, for example.
The drive clutch is connected to the drive shaft by a belt, and the connection state of the electromagnetic clutch is controlled by the engine control unit 50 according to the operating state of the engine (see FIG. 7) as described later. (Not shown).

The air pump 55 is provided with an air control valve (ACV) 56 at the secondary air discharge end of the secondary air main supply passage 60, for example, as shown in FIG. 2nd secondary air supply passage
The first and second secondary air supply nozzles 53 and 54 are controlled via 61 and 62 to supply secondary air according to the engine operating condition as shown in FIG.

That is, as is clear from FIG. 4, the air control valve 56 connects the secondary air main supply passage 60 to the first secondary air supply passage 61 and the second secondary air supply passage 62, respectively. On the other hand, the relief passage 63 is provided, and the first and second secondary air control control valves 65, 66 are provided at the connecting portions of the passages 60 to 63.
Is provided. The first control valve 65 for secondary air control is attached to one end of a slidable rod 67, and the secondary air main supply passage 60 is provided with a relief passage 63.
And a valve body 68 that switches between a valve closed position for communicating with the secondary air main supply passage 60 and an valve open position for communicating the secondary air main supply passage 60 with the first and second secondary air supply passages 61, 62. , A spring 69 for urging the valve body 68 toward the closed position.
And a diaphragm 70 connected to the other end of the rod 67.
And a negative pressure chamber 71 defined by the diaphragm 70,
The diaphragm 70 is compacted in the negative pressure chamber 71, and the diaphragm 70 is attached to the valve body 68.
And a spring 72 for urging the valve toward the valve closing position, and the negative pressure chamber 71 communicates with the inside of the intake pipe 42 downstream of the throttle valve 46 of FIG. 2 via the first negative pressure introducing passage 73. In the middle of the first negative pressure introducing passage 73, the first communicating state of the negative pressure chamber 71 or the communicating state of the negative pressure chamber 71 to the intake pipe 42 downstream of the throttle valve 46 is switched to each other. An electromagnetic valve 75 is provided, and when the first electromagnetic valve 75 is turned on, the negative pressure chamber 71 is opened to the atmosphere to position the valve element 68 at a closed position by the urging force of the springs 69 and 72. While relieving the secondary air from the air pump 55, the negative pressure chamber 71 is activated when the first solenoid valve 75 is turned off.
By introducing intake negative pressure into the valve body 68, the valve body 68 is positioned at the valve open position against the biasing force of the springs 69 and 72, and the secondary air from the air pump 55 is supplied to the first or second secondary air. The passages 61 and 62 can be supplied.

Further, the second control valve 66 for secondary air control
Is attached to one end of a slidable rod 80, and when the valve body 68 of the first control valve 65 for controlling secondary air is in the open position, the secondary air main supply passage 60 is connected to the first A first valve position for communicating with the secondary air supply passage 61 and a second valve position for communicating the secondary air main supply passage 61 with the second secondary air supply passage 62 are cut off between two positions. A valve body 82 to be replaced, a spring 83 for urging the valve body 82 toward the second valve position, a diaphragm 84 connected to the other end of the rod 80, and a negative valve defined by the diaphragm 84. It comprises a pressure chamber 85 and a spring 86 that is compressed inside the negative pressure chamber 85 and biases the diaphragm 84 so that the valve body 82 moves toward the second valve position. From the negative pressure introducing passage 87 and the first solenoid valve 75, the first negative pressure introducing passage 73 on the intake pipe 42 side in FIG. Through throttle valve
46 is in communication with the intake pipe 42 downstream. In addition, the second
In the middle of the negative pressure introduction passage 47, a second solenoid valve 89 for switching the communication state of the negative pressure chamber 85 to the atmosphere communication passage 88 or the first negative pressure introduction passage 73 is provided. Second solenoid valve
When 89 is turned on, the negative pressure chamber 85 is opened to the atmosphere so that the valve element 82 is positioned at the second valve position by the urging force of the springs 83 and 86 to supply the secondary air from the air pump 55 to the second secondary air. The negative pressure chamber 8 is supplied to the second secondary air supply nozzle 54 through the passage 62 while the second solenoid valve 89 is turned off.
By introducing intake negative pressure to 5, the valve body 82 is moved to both springs 83,86.
Positioned in the first valve position against the urging force of the air pump
The secondary air from 55 is supplied to the first secondary air supply nozzle 53 through the first secondary air supply passage 61.

In addition, the first and second secondary air supply passages 61, 62
The second control valve for secondary air control 66
When the valve body 82 is in the second valve position, a bypass passage 90 is formed which is a small hole that bypasses the valve body 82 and connects the upstream and downstream sides of the valve body 82.

In addition, in the above-mentioned configuration, each electrically operated portion is controlled by a control signal from the engine control unit 50. The engine control unit 50 is mainly composed of, for example, a microprocessor (CPU), is provided with memories (ROM and RAM) and an interface circuit, and is configured as shown in FIG. 5 (functional block diagram) described later.

That is, this engine control unit 50
First, the intake air amount detection signal Q from the air flow meter 45
And a basic injection pulse width setting circuit 101 for setting the basic injection pulse width of the supplied fuel based on the engine speed detection signal N from the engine speed detection means 100, the engine speed detection signal N and the throttle opening sensor. By comparing the throttle valve opening signal θ from 47 with predetermined area reference data on the engine map, for example, the operating state of the engine body 1 is shown in FIG. Area), B ₁ area (low rotation and low load area), B ₂ area (low rotation and high load area), B ₃ area (high rotation and low load area), B ₄ , B ₅ area (high rotation and high load area) Oxygen when the ON signal for determining the B ₄ or B ₅ region is output from the region determination circuit 102 that determines whether it is in any of the regions and outputs an ON signal at the time of the determination, and the region determination circuit 102. Oxygen concentration from concentration detector 103 An AND circuit 104 for passing the time signal O _2, and the pulse width correction circuit 105 which corrects the basic injection pulse width signal from the basic injection pulse width setting circuit 101 by the oxygen concentration signal O ₂ which has passed through the AND circuit 104, A fuel injector drive circuit 106 for driving the fuel injector 49 according to an output signal from the pulse width correction circuit 105, and O corresponding to each area of the area determination circuit.
An N valve signal is input through gate circuits (AND gates) G _{1 to} G ₅ and a solenoid valve control circuit 107 for controlling the supply of secondary air corresponding to the determination area is configured.

The engine control unit 50 exhausts the basic fuel injection amount calculated based on the intake air amount detection signal Q and the engine speed detection signal N only in the high rotation and high load regions B ₄ and B ₅ in this embodiment. Fuel injection is performed from the fuel injector 49 while performing feedback correction according to the residual oxygen concentration therein, and the engine speed detection signal N and throttle valve opening detection signal θ
The respective secondary air supply regions (A, B _{1 to} B ₅ ) are determined based on the above, and the secondary air control control valves 65 and 66 are controlled based on the determination results, respectively. Each of the secondary air supply nozzles 5 is activated by operating the air supply nozzles 53, 54.
The amount of secondary air supplied from 3,54 is controlled according to the engine operating range. Moreover, in that case, in the region where the opening / closing control valve 26 of the intake air recirculation passage 25 in the secondary air supply region is opened (corresponding substantially to the region of B ₄ + B _{5 in} FIG. 6), the region determination signal is added. Based on this, secondary air reduction control (FIG. 6) is performed as described later.

Before that, first of all, this engine control unit 50
The general secondary air supply control function of will be described below. As shown in FIG. 7, the throttle valve opening θ is equal to the predetermined opening θ.
_{When the} engine speed N is higher than _L or the engine speed N is higher than a predetermined speed, that is, when the engine is operating in the maximum rotation or maximum load region (air cut region) A, the region determining circuit 102 causes the first solenoid valve 75 to move. Body of the control valve 65 for the first secondary air control by energizing the
By positioning the 68 in the valve closing position, the air pump
The supply of secondary air from 55 to the first and second secondary air supply nozzles 53, 54 is stopped (air cut control). On the other hand, when the throttle valve 46 is in the operating range B (B _{1 to} B ₅ ) where the opening is less than the predetermined opening θ _L , the first solenoid valve 75 is used.
The valve body 68 of the first secondary air control valve 65 is positioned at the valve opening position by stopping the power supply to the secondary air supply nozzles 53, 54 to the first and second secondary air supply nozzles 53, 54. Enables air supply (air supply control).

And, in this secondary air supply region B (B _{1 to} B ₅ ),
First, when the operating state of the engine is in the low rotation / low load region B ₁ and the high rotation / low load region B ₃ , the second solenoid valve 89 is deenergized to stop the second secondary air control control valve 66. By positioning the valve element 82 at the first valve position, the secondary air from the air pump 55 is supplied only to the first secondary air supply nozzle 53. Since these regions contain a large amount of unburned components in the exhaust gas, both the first catalytic converter 51 and the second catalytic converter 52 are made to function as oxidation catalysts, so that hydrocarbons and carbon monoxide in the unburned components are effective. Therefore, secondary air is supplied only to the upstream side of each of the catalytic converters 51, 52, that is, the exhaust ports 15, 16 by the first secondary air supply nozzle 53. In addition, during the period from the time when the operating state of the engine shifts from the B ₁ range to the low rotation and high load range B ₂ until the predetermined time elapses, the second solenoid valve 89 is de-energized as described above. By positioning the valve body 82 of the second control valve 66 for controlling the secondary air at the first valve position, the secondary air is supplied from the first secondary air supply nozzle 53, while the above predetermined time has elapsed. In the subsequent B ₄ region, by energizing the second solenoid valve 89 to position the second control valve 66 for controlling the secondary air at the second valve position, the secondary air is mainly fed to the second valve. It is supplied from the secondary air supply nozzle 54 and a part of it is also supplied from the first secondary air supply nozzle 53 via the bypass passage 90 (port leakage region).
B ₄ ).

Therefore, in the present embodiment, the entire B ₁ + B ₂ + B ₃ + B ₄ region including the B ₂ region is considered as the secondary air supply region (port air region) by the first secondary air supply nozzle 53. To When the determination output each of these regions is outputted from the region determining circuit 102, the output is supplied to the solenoid valve control circuit 107 as described above through the gate circuit G ₂ ~G _4, The supply control of the secondary air as described above is performed.

Next, when the operating state of the engine is in the high rotation and high load region B ₅ , the output of the region determination circuit 102 causes the second solenoid valve 89 to be energized and the valve of the second secondary air control valve 66 is controlled. By positioning the body 82 in the second valve position, the secondary air from the air pump 55 is supplied to the second secondary air supply nozzle 54.

That is, at least one of the first and second catalytic converters 51 and 52 needs a reducing atmosphere in this region because a large amount of nitrogen oxide (NOx) is discharged. Therefore, it is necessary to avoid the supply of the secondary air to the upstream of both catalytic converters 51, 52 by the first secondary air supply nozzle 53. Moreover, in this case, the required air amount is smaller than that in the case where both the first and second catalysts 10 and 11 are used as the oxidation catalyst.

Therefore, while only the second secondary air supply nozzle 54 is selected as the secondary air supply nozzle, the secondary air is supplied at a low capacity to reduce the engine load and improve the fuel consumption performance. .

Next, the secondary air supply amount correction operation by the engine control unit 50 when the pump loss due to the intake air recirculation is reduced will be described with reference to the flowchart in FIG.

First, in step S ₁ , the number of engine circuits N, the throttle opening θ, and the intake air amount Q are used as various input data necessary for control.
Read each of.

Next, from the throttle opening θ and the engine speed N in the input data, the current engine operating state is made to correspond to the region on the map of FIG.
Opening area of 25 on-off control valves 26 (for example, low rotation and low load area)
It is determined whether or not As a result, in the case of NO (closed area), since generally conventional high compression ratio is set by an intake recirculation passage 25 is closed, the map data A of FIG. 8 in the next step S ₃ reads the normal secondary air supply amount indicated, further proceeds to step S _5, in response to the read volume by controlling the air control valve 56 described above for supplying secondary air in the same manner as described above.

On the other hand, in step S _2, in the case of YES (open area), since a state in which the effective compression ratio of the engine is controlled to be lower for pumping loss reduction, contrary proceeds to step S ₄ and the Then, the secondary air supply amount by the map data B smaller than the map data A in FIG. 8 by a predetermined amount is read out,
The control operation of the air control valve 56 in step S ₅ is performed based on the read value to supply the secondary air whose amount is reduced and corrected in accordance with the reduction amount of the compression ratio than in the case of the high compression ratio.

That is, in steps S ₄ and S ₅ , in the pump loss reduction region in which the effective compression ratio of the engine is set to be low, the amount of secondary air supply is smaller than the original amount of secondary air supply in accordance with the decrease of the effective compression ratio. The secondary air supply amount is controlled so as to supply the secondary air.

As a result, the effective compression ratio of the engine is reduced, and even if the combustion speed in the working chamber is reduced and the temperature of the exhaust gas becomes high, the secondary air supply amount itself is reduced and the combustion reaction on the exhaust side is reduced. Since the speed decreases, the increase in temperature is suppressed within a predetermined range that does not impair the function of the catalytic converter.

At this time, the combustion state in the working chamber deteriorates and the amount of unburned gas discharged from the working chamber increases, but since the secondary air is normally supplied excessively, the secondary air supply amount If the decrease is slight, there is no particular problem in terms of exhaust gas purification performance.

(Effects of the Invention) As described above, the present invention corresponds to a pump loss reducing device that reduces pump loss by substantially shortening an intake stroke in a specific operating region, an exhaust gas purification device, and an operating region. A secondary air control device for an engine, comprising: a secondary air supply device for controlling the amount of secondary air supplied to the exhaust gas purification device, wherein the exhaust gas purification device is supplied to the exhaust gas purification device when the pump loss reduction device operates. Correct the secondary air supply amount 2
It is characterized in that a secondary air supply amount correcting means is provided.

Therefore, according to the present invention, in the pump loss reduction region where the intake stroke is substantially shortened, the secondary air is supplied so that the secondary air is supplied by a predetermined amount smaller than the original secondary air supply amount according to the shortened amount. The air supply can be controlled.

Therefore, the effective compression ratio of the engine is substantially reduced by shortening the intake stroke, so that the secondary air supply amount itself is reduced even if the combustion speed is lowered and the exhaust gas becomes hot in consideration of the expansion stroke. As a result, the combustion reaction rate on the exhaust side decreases and the rise in temperature is suppressed within a predetermined range that does not impair the function of the exhaust gas purification device such as a catalytic converter. Absent.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is a system schematic diagram of a secondary air control device for an engine according to an embodiment of the present invention, and FIG. 3 is an engine main body in the same embodiment device. 4 is a sectional view showing the structure of the air control valve in the apparatus of the embodiment, FIG. 5 is a schematic block diagram showing the function of the engine control unit in the apparatus of the embodiment, FIG. 6 shows 2 when the engine compression ratio is variable by the engine control unit.
A flow chart showing the secondary air supply amount correcting operation, and FIGS. 7 and 8 are control map diagrams used for the secondary air supply control of the apparatus of the above embodiment. 1 …… Rotary piston engine body 2,3 …… Trochoid space 4,5 …… Rotor housing 6,8 …… Side housing 7 …… Intermediate housing 10,11 …… Rotor 13A ～ 13C …… Working chamber 14A ～ 14C …… Operating chamber 19 …… Exhaust pipe 21,22 …… Main intake port 25 …… Intake recirculation passage 26 …… Open / close control valve 40 …… Open / close valve actuator 41 …… Duty solenoid 45 …… Air flow meter 46 …… Throttle Valve 47 …… Throttle opening sensor 48 …… Acceleration sensor 50 …… Engine control unit 51 …… First catalytic converter 52 …… Second catalytic converter 53 …… First secondary air supply nozzle 54 …… Second 2nd secondary air supply nozzle 55 ...... Air pump 60 ...... Secondary air main supply path 75 ...... First solenoid valve 89 ...... Second solenoid valve 102 ...... Area judgment circuit

Claims (1)

[Claims] Claim: What is claimed is: 1. A pump loss reducing means for reducing pump loss by substantially shortening an intake stroke in a specific operating region, an exhaust gas purification device, and an amount of secondary air supplied to the exhaust gas purification device in correspondence with the operating region. In the secondary air control device for an engine, which is provided with a secondary air supply device for controlling the exhaust gas, the exhaust air purification device is supplied with 2 when the pump loss reduction device operates.
A secondary air control device for an engine, characterized in that a secondary air supply amount correcting means for reducing and correcting the secondary air supply amount is provided.