JPS631748A - Engine secondary air control device - Google Patents

Abstract

PURPOSE:To permit a temperature increase in an exhaust gas cleaning device to be restricted to a proper range, by providing means for reducingly correcting an amount of secondary air supplied to the exhaust gas cleaning device when pump loss reducing means is actuated for reducing a pump loss by reducing an intake stroke in a specific driving region. CONSTITUTION:Pump loss reducing means comprises intake air feedback passage 25 for alternately forming first and second communicating conditions which causes a compression stroke operating chamber of one of 2 rotary housings 4, 5 disposed side by side to communicate with an intake stroke operating chamber of the other rotary housing, and an opening and closing valve 26 disposed in the intake air feedback passage 25. A first secondary air supply nozzle 53 is disposed upstream of first and second catalyst converters 51, 52 disposed in the middle of an exhaust gas pipe 19 and a second secondary air supply nozzle 54 is disposed between both th catalyst converter 51, 52. In the case, when the opening and closing valve 26 is opened, an air control valve 56 is controlled so that secondary air of which amount is reducingly corrected is supplied to the catalyst converters 51, 52.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) 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 extract all of the heat energy generated in the cylinders as extraction power, and a considerable portion of it is lost as various losses such as heat loss and mechanical loss, which reduces fuel consumption. This is one of the obstacles to improvement. One of these mechanical losses is the pump loss during the intake and exhaust strokes, and this pump loss is especially larger at low loads than at high loads, so this is especially true for automobile engines that are frequently used in medium and low load ranges. , which greatly hinders the improvement of fuel efficiency.

On the other hand, it is known that installing an engine with a small stroke volume in the same vehicle improves fuel efficiency, but this is because the engine operates under a relatively high load, which greatly reduces pump loss. This is thought to be one of the reasons. Therefore, if the engine performs the same function as a small stroke volume engine only at low loads, pump loss at low loads can be reduced and fuel efficiency can be improved without sacrificing the engine's required characteristics at high output. It is thought that it is possible to do so.

In other words, in order to reduce the pump loss at low loads, it is necessary to reduce the throttling loss due to the increase in suction negative pressure based on the small throttle valve opening during the suction stroke and the compression loss during the compression stroke. . This is true not only for reciprocating piston engines but also for rotary piston engines.As a means for this purpose, for example, in a reciprocating piston engine, as described in JP-A No. 50-59610, In addition to the passage, an intake recirculation passage (bypass passage) is provided to allow part of the intake air to leak into the intake passage during the compression stroke, and an on-off control valve for output adjustment is provided for this intake recirculation passage. A first conventional technique is known in which the intake air recirculation amount is specifically controlled by adjusting the opening degree and valve closing timing of a control valve according to the load condition of the engine.

That is, this first conventional technology connects an intake device of a low-repetition piston engine with an intake passage that supplies intake air from the atmosphere into the cylinder during the intake stroke of the engine, and a part of the intake passage that communicates with the cylinder. and an intake recirculation passage that recirculates a portion of the intake air in the cylinder to the intake passage during the compression stroke of the engine, and an opening/closing control valve that opens and closes this intake air recirculation passage. The actual filling amount of intake air is controlled by controlling the state according to the operating region and adjusting the amount of intake air recirculation.

According to such an intake system for a rotary piston engine, the opening/closing control valve essentially functions as a means for varying the engine's effective compression ratio, reducing pump loss at low loads, and greatly improving fuel efficiency. This is expected to improve.

- On the other hand, even in engines that employ the variable compression ratio structure as described above, in order to purify the exhaust gas, fresh air is introduced into the exhaust boat section of the engine, and the exhaust gas remains in a high temperature state. The unburned components (hydrocarbons, −
Usually, a secondary air supply device is provided to burn off (oxidation treatment) carbon oxide).

When supplying such secondary air, it is not always possible to obtain a sufficient purification effect (for example, NOx cannot be treated) if the exhaust gas is purified only by supplying the secondary air. Recently, in many cases, the secondary air supply device is combined with other after-treatment devices, such as a three-way catalytic converter, to create an efficient exhaust purification system centered on the secondary air supply device. oxidation and reduction treatment systems).

By the way, when an exhaust purification system is configured by combining catalytic converters in this way, the amount of exhaust gas components supplied from the engine to the catalytic converter section inevitably depends on the operating state (rotation or load range) of the engine. It will be different. Therefore, the state and amount of secondary air supplied by the secondary air supply device must be properly controlled depending on the operating state of the engine.

From this point of view, there is a secondary air control device as a second prior art that variably controls the supply state of secondary air to the catalytic converter according to the operating state of the engine (for example, 54-35251).

(Problems to be solved by the invention) By the way, in the case of the second prior art mentioned above,
The secondary air is supplied by an air pump that is constantly driven by the engine, and the specific adjustment of the secondary air supply amount itself is controlled according to the operating range specified by the throttle opening and engine speed. Normally, the adjustment is controlled by air control pulp.

However, as in the case of the second prior art described above, the configuration of controlling the amount of secondary air supplied to the exhaust gas purification device according to the operating range is replaced by a pump that uses a variable effective compression ratio of the engine as in the first prior art described above. When applied to an engine equipped with loss reduction means, the following problems arise.

That is, in the pump loss reduction region, the effective compression ratio of the engine is lowered, so the compression pressure in the combustion chamber is lowered, and therefore lower than the Vfl temperature. As a result, the combustion efficiency of the air-fuel mixture decreases, the combustion condition deteriorates, and high-temperature, unburned gas is directly discharged to the exhaust port and the catalytic converter side. Nevertheless, a large amount of secondary air, determined solely by the operating range, is supplied and comes into contact with the unburned gas, so that the rapid reburning of the unburned gas in this section causes the exhaust gas temperature to rise. A situation occurs in which the temperature rises abnormally and impairs the function of the three-way catalytic converter.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above problems, and is a pump loss reduction means that reduces pump losses by substantially shortening the intake stroke in a specific operating region. A secondary air control device for an engine, comprising: an exhaust purification device; and a secondary air supply means for controlling the amount of secondary air supplied to the exhaust purification device in accordance with an operating region; 2 supplied to the exhaust purification device during operation.
A secondary air supply amount correcting means is provided for reducing and correcting the secondary air supply amount.

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

Therefore, by shortening the intake stroke, the effective compression ratio of the engine is reduced, so even if the combustion speed decreases and the exhaust gas becomes hot due to the expansion stroke,
By reducing the secondary air supply amount itself, the combustion reaction rate on the exhaust side is reduced, and the temperature rise is suppressed within a predetermined range that does not impair the function of the exhaust purification device such as the catalytic converter. Therefore, problems like the conventional ones do not occur.

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

First, in FIG. 2, the symbol l indicates, for example, a two-cylinder rotary piston engine body, and this rotary piston engine body (hereinafter referred to as the engine body) l has its inner side as shown in FIG. Trochoid space 2.
3, and three side housings (a common central part) located on both sides of these two rotor housings 4.5 and closing both sides of each rotor housing 4,5. 6.7.8 The side housing is especially referred to as the intermezzo-eight housing.
It is composed of. In the trochoid space 2.3 of each rotor housing 4.5, there are grooves that are inscribed in the trochoid inner circumferential surfaces 4a, 5a inside the rotor housing 4.5 and mutually around the eccentric shaft 9. Two substantially triangular rotors 11, which rotate planetarily with a phase difference of 180 degrees, are loosely fitted.

The above rotor 10. three outer peripheral surfaces 10a-10c of I+,
Three working chambers 13A-13G% 14A-140 are formed between 11a=Ilc and the trochoid inner peripheral surfaces 4a, 5a of the rotor housing 4.5, respectively. In addition, each of the above rotor housings 4.5
The trochoid inner peripheral surface 4a corresponding to the lower part of one side of
Exhaust ports 15 and 16 are opened in 5a,
The exhaust ports 15, 16 are commonly communicated with an external exhaust pipe 19 via exhaust ports 17 and I8.

On the other hand, the side housing located between each rotor housing 4.5 of the three side housings 6 to 8, that is, the intermezoate housing 7, has two intake boats 21 and 22 that communicate with the intake pipe 42, respectively. is opened toward the working chamber in each trochoid space on the side of each rotor housing 4.5. In addition, this intermezzo housing has a compression stroke operation of the first rotor housing 4 on one side (front side) corresponding to the planetary rotation having a phase difference of 180 degrees between the two rotors 10 and 11. The chamber (any one of 13A to 13G) is placed on the other side (rear side) of the second rotor housing 5.
-14G), and the compression stroke working chamber (14A to 14C) of the second rotor housing 5 on the other side (rear side) is connected to the - side (
(Front side) An intake recirculation passage 25 is formed which alternately communicates with the intake stroke working chamber (any one of 13A to 13c) of the first rotor housing 4 and a second communication state. This intake air recirculation passage 25 can be easily provided by forming a through hole in a predetermined position of the intermezoate housing 7 to communicate the two trochoid spaces 2.3, as shown in FIG. . and,
A disc-shaped butterfly-type opening/closing control valve 26 is installed in the center of the intake recirculation passage 25, and the opening/closing control valve 26 is controlled to be fully closed in high-speed and high-load areas. In the low-speed, low-load region, the valve is opened according to the load amount, and the opening cross-sectional area of the intake air recirculation passage 25 is made variable to control the amount of recirculated intake air.

The opening/closing control valve 26 is operated by an opening/closing valve actuator 40 having a diaphragm configuration, which is driven according to the operating state (valve position) of a duty solenoid 41, which is, for example, a three-way solenoid valve, whose operation is controlled by an engine control unit 50, which will be described later. Its opening/closing state is specifically controlled.

- On the other hand, the intake boats 21 and 22 each have an intake pipe 4
A surge tank 44 is formed in the intake pipe 42, 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, respectively. ing. The intake air amount detection signal Q of the air flow meter 45 is input manually to the engine control unit 50. A throttle opening sensor 47 is attached to the throttle valve 46, and a throttle opening detection signal θ from the throttle opening sensor 47 is also input to the engine control unit 50. Further, reference numeral 49 is a fuel injector, and the above-mentioned intake pipe 4
It is provided in 2. Note that numerals 30 and 31 are sub-intake boats.

Then, the engine control unit 50 manually performs predetermined calculations on the throttle valve opening θ detected by the throttle opening sensor 47, the engine rotation speed N, and the engine coolant temperature Tw, and controls the duty solenoid 4I. Controls the operating state. A duty solenoid 41, which is a three-way solenoid valve, selectively communicates the working chamber of the on-off valve actuator 40 with the diaphragm structure to either the atmosphere side P or the intake pipe 42 side (negative pressure side) P. By this, the driving state (opening/closing of the valve) of the on-off valve actuator 40 is controlled.

On the other hand, near the upstream end of the exhaust passage of the exhaust pipe 19 that discharges exhaust gas from the engine body 1, there is a first catalytic converter 51 and a second catalytic converter 51 located downstream of the first catalytic converter 51 by a predetermined distance. catalytic converters 52 are respectively arranged.

and the first and second catalytic converters 51.5
A first secondary air supply nozzle 53 for supplying boat air is provided at the exhaust port 15 and 16 on the upstream side of the exhaust port 2.
In addition, both the first and second catalytic converters 51 and 52
Second secondary air supply nozzles 54 for supplying split air are fitted into the exhaust passages between them.

Further, the reference numeral 55 indicates two ports between the first and second secondary air supply nozzles 53.54, the exhaust port 15.16, and the first and second catalytic converters 51 and 52, respectively.
The air pump 55 is connected to the drive shaft of the engine main body 1 by a belt, for example, via a boob with an electromagnetic clutch, and
As described later, the connection state of the electromagnetic clutch is controlled by an engine control unit 50 according to the operating state of the engine (see FIG. 7) (not shown).

The air pump 55 is provided with an air control valve (ACV) 56 as shown in FIG. The above-mentioned first and second secondary air supply passages 61,62 are
The supply of secondary air to the secondary air supply nozzles 53 and 54 is controlled according to the engine operating conditions as shown in FIG.

That is, as is clear from the upper third air control valve FIG. 4, the secondary air main supply passage 60 is communicated with the first secondary air supply passage 61 and the second secondary air supply passage 62, respectively. On the other hand, the relief passage 63
First and second secondary air control valves 65 and 66 are provided at the connection portions of the passages 60 to 63. The first secondary air control control valve 65 is attached to one end of a slidable rod 67, and is set to a closed position where the secondary air main supply path 60 is communicated with the relief passage 63. The main supply passage 60 is connected to the first and second secondary air supply passages 6.
1.62, a valve body 68 that switches between two positions, a valve open position and a valve open position, a spring 69 that urges the valve body 68 toward a closed position, and a spring 69 that is connected to the other end of the rod 67. A connected diaphragm 70 and the diaphragm 70
The spring 72 is compressed into the negative pressure chamber 71 and biases the diaphragm 70 so that the valve body 68 moves toward the closed position. 71 is connected to the second
It communicates with the intake pipe 42 downstream of the throttle valve 46 in the figure, and the atmosphere communication passage 74 of the negative pressure chamber 71 or the throttle valve 46 is connected in the middle of the first negative pressure introduction passage 73.
A first solenoid valve 75 that mutually switches communication states into the downstream intake pipe 42 is interposed, and the first solenoid valve 7
5, when the negative pressure chamber 71 is opened to the atmosphere, the valve element 68 is positioned at the closed position by the biasing force of the springs 69 and 72, and the air pump 55 is turned on.
While relieving the next air, the O of the first solenoid valve 75 is
When F''F is activated, the intake negative pressure is introduced into the negative pressure chamber 71, and the valve body 68 is positioned at the open position against the biasing force of the springs 69, 72, thereby allowing the secondary air from the air pump 55 to flow. First or second secondary air supply passage 61.6
This makes it possible to supply 2.

Further, the second secondary air control control well 66 is attached to one end of the slidable rod 80, and the valve body 68 of the first secondary air control control valve 65 is attached to one end of the slidable rod 80.
is in the valve open position, the secondary air main supply path 6
0 to the first secondary air supply passage 61 and a second valve position that communicates the secondary air main supply passage 61 to the second secondary air supply passage 62. A valve element 82 that switches between positions, a spring 83 that biases the valve element 82 toward the second valve position, a diaphragm 84 connected to the other end of the rod 80, and a A negative pressure chamber 85 is defined, and a second valve body 82 is compressed in the negative pressure chamber 85 and connects a diaphragm 84.
The negative pressure chamber 85 is located on the side of the intake pipe 42 in FIG. 2 from the second negative pressure introducing passage 87 and the first solenoid valve 75. It communicates with the intake pipe 42 downstream of the throttle valve 46 via a first negative pressure introduction passage 73 . Further, a second TL@valve 89 is interposed in the middle of the second negative pressure introduction passage 47 to switch the communication state of the negative pressure chamber 85 to the atmosphere communication passage 88 or the first negative pressure introduction passage 73. When the second solenoid valve 89 is turned ON, the negative pressure chamber 85 is opened to the atmosphere, and the valve body 82 is positioned at the second valve position by the biasing force of the springs 83 and 86, and the air pump 55 is removed. The secondary air is passed through the second secondary air supply passage 62 to the second
At the same time, when the OF2 of the second solenoid valve 89 is activated, the intake negative pressure is introduced into the negative pressure chamber 85, and the valve body 82 is biased by the biasing force of both springs 83 and 86. The secondary air pump 55 is positioned at the first valve position to supply the secondary air from the air pump 55 to the first secondary air supply nozzle 53 via the first secondary air supply passage 61 .

Further, the first and second secondary air supply passages 61, 6
2, the valve body 82 of the second secondary air control control well 66 is in the second valve position.
A bypass passage 90 is formed by a small hole that bypasses the valve body 82 and communicates the upstream and downstream sides of the valve body 82.

In the above configuration, each electrically operated part is controlled by a control signal from the engine control unit 50.

The engine control unit 50 includes, for example, a microprocessor (CPU) as its core, and a memory (ROM).
and RAM) and an interface circuit, and is configured as shown in FIG. 5 (functional block diagram), which will be described later.

That is, this engine control unit 50 is
First, a basic injection pulse width setting circuit 101 sets the basic injection pulse width of supplied fuel based on the intake air amount detection signal Q from the air flow meter 45 and the engine rotation speed detection signal N from the engine rotation speed detection means 100. By comparing the engine speed detection signal N and the throttle valve opening signal θ from the throttle opening sensor 47 with predetermined area reference data on the engine map, the operating state of the engine main body l can be determined as shown in FIG. 7, for example. Area A (highest rotation maximum load area), Area B (low rotation low load area), and Area B (low rotation high load area) are shown separately.
, B, (high rotation, high negative street area), and B5 (high rotation, high load).
an area determination circuit 102 that outputs an ON signal at the time of the determination;
AND circuit 104 that passes the oxygen concentration and variable signal 02 from the oxygen concentration detector 103 when the ON signal for determining the B4 and B5 regions is output from the region determination circuit 102;
and a pulse width correction circuit 105 that corrects the basic injection pulse width signal from the basic injection pulse width setting circuit 101 using the oxygen concentration signal O7 passed through the AND circuit 104, and the output signal from the pulse width correction circuit 105. A fuel injector drive circuit 106 that drives the fuel injector 49 accordingly, and a kON signal corresponding to each area of the area determination circuit are inputted via gate circuits (A N D gates) Gl-G to determine the determination area. Solenoid valve control circuit 10 for controlling the supply of secondary air corresponding to
It consists of 7.

In this embodiment, the engine control unit 50 calculates the basic fuel injection amount calculated based on the intake air amount detection signal Q and the engine rotation speed detection signal N. The fuel is injected from the fuel injector 49 with feedback correction based on the residual oxygen concentration, and each area for secondary air supply (A, BI~
B5) is determined, and the secondary air supply nozzles 53.54 are actuated by controlling the secondary air control control valves 65, 66, respectively, based on the determination results. The amount of secondary air supplied from 54 is controlled according to the engine operating range. Moreover, in that case, in the area where the on-off control valve 26 of the intake air recirculation passage 25 in the secondary air supply area is opened (approximately corresponding to the area of 84+Bs in FIG. 6),
Based on the area determination signal, secondary air reduction control (FIG. 6), which will be described later, is performed.

Before that, first of all, this engine control unit 50
To explain the general secondary air supply control function of the
L or the engine speed N is higher than the predetermined speed, that is, when the engine operating state is in the maximum speed or maximum load region (air cut region) A, the region determination circuit 102 causes the first solenoid valve 75 to By energizing the first secondary air control control valve 65,
By positioning the valve body 68 in the closed position, the supply of secondary air from the air pump 55 to the first and second secondary air supply nozzles 53 and 54 is stopped (air cap control). - On the other hand, when the opening degree of the throttle valve 46 is in the operating region B (B, ~B5) where the opening degree is less than the predetermined opening degree θL, the energization to the first electromagnetic valve 75 is stopped, so that the Valve body 68 of control valve 65 for control
By positioning the nozzle in the open position, it is possible to supply secondary air to the first and second secondary air supply nozzles 53 and 54 (air supply control).

Of this secondary air supply region l3 (B, ~B,), first, when the operating state of the engine is in the low rotation and low load region B and the high rotation and low load region B3, the second solenoid valve 89 is By stopping the energization and positioning the valve body 82 of the second secondary air control control well 66 at the first valve position, the secondary air from the air pump 55 is directed only to the first secondary air supply nozzle 53. supply to In these regions, there are many unburned components in the exhaust gas, so the first catalytic converter 51 and the second catalytic converter 52 both function as oxidation catalysts to effectively remove hydrocarbons and carbon oxides in the unburned components. Therefore, secondary air is supplied to the upstream side of each of the catalytic converters 51 and 52, that is, to the exhaust port 15 and 16 by only the first secondary air supply nozzle 53. In addition, if the engine operating condition changes from the above B+ area to the low rotation high load area B2
During the period from the time when the transition to the second control well 66 for secondary air control occurs until the predetermined time elapses, the second solenoid valve 89 is de-energized in the same way as described above.
By positioning the valve at the first valve position, secondary air is supplied from the first secondary air supply nozzle 53, while the second solenoid valve 89 By energizing the second secondary air control valve 66 to position it at the second valve position, secondary air is mainly supplied from the second secondary air supply nozzle 54 and a part of it is supplied to the second secondary air supply nozzle 54. The first
It is also supplied from the secondary air supply nozzle 53 (boat leakage area B).

Therefore, in this embodiment, it can be broadly classified into B.

B + + B t + B 3 + B 4 containing the area
The entire area will be considered as a secondary air supply area (port air area) by the first secondary air supply nozzle 53. When a determination output for determining each of these regions is output from the region determination circuit 102, the output is supplied to the solenoid valve control circuit 107 as described above via the gate circuits 62 to G4, and The supply of secondary air is controlled as follows.

Next, when the operating state of the engine is in the high rotation and high load region B, the second
By energizing the solenoid valve 89, the valve body 82 of the second secondary air control control well 66 is positioned at the second valve position, thereby supplying the secondary air from the air pump 55 to the second secondary air supply. is supplied to the nozzle 54.

That is, since this region discharges a large amount of nitrogen oxides (N OK), at least one of the first and second catalytic converters 51 and 52 requires a reducing atmosphere. Therefore, supply of secondary air to the upstream side of both catalytic converters 51 and 52 by the first secondary air supply nozzle 53 must be avoided. Moreover, in this case, the above first
The amount of air required is smaller than when both the second catalyst 10.2 and the second catalyst 10.2 are used as oxidation catalysts.

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

Next, the secondary air supply amount correction operation by the engine control unit 50 when reducing the pump loss due to the intake air recirculation will be described with reference to the flowchart of FIG. 6.

First, in step S1, engine rotation speed N, throttle opening θ, and intake air ff are input as various input data necessary for control.
Read each of 1Q.

Next, based on the throttle opening θ and the engine speed N in the input data, the current engine operating state is determined according to the area on the map shown in FIG.
It is determined whether or not the opening/closing control valve 26 of No. 5 is in an open region (for example, a low rotation and low load region). As a result, in the case of No (closed region), the intake recirculation passage 25 is closed and the compression ratio is generally set to a normal high compression ratio. The secondary air supply amount is read out, and the process further proceeds to step S, where the above-mentioned air control valve 56 is controlled in accordance with the read amount to supply the same secondary air as described above.

On the other hand, in the case of YES (open region) in step S, the effective compression ratio of the engine is controlled to be low in order to reduce pump loss, so contrary to the above, the process moves to step S4. , read out the secondary air supply amount according to the map data B which is smaller than the map data A by a predetermined amount in FIG. Supply of secondary air is corrected to reduce the amount in accordance with the amount of reduction in compression ratio.

That is, in the case of steps S- and Ss, in the pump loss reduction region where the effective compression ratio of the engine is set low, the amount of secondary air supplied is a predetermined amount less than the original secondary air supply amount according to the reduction in the effective compression ratio. The secondary air supply amount is controlled so as to supply secondary air.

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

At this time, the combustion condition in the working chamber deteriorates and the amount of unburned gas discharged from the working chamber increases, but normally the secondary air is supplied in excess, so the amount of secondary air supplied is reduced. If the decrease is small, there is no particular problem in terms of exhaust gas purification performance.

(Effects of the Invention) As explained above, the present invention provides a pump loss reduction means that reduces pump loss by substantially shortening the intake stroke in a specific operating region, an exhaust purification device, and a pump loss reduction device that reduces pump loss by substantially shortening the intake stroke in a specific operating region. A secondary air control device for an engine includes a secondary air supply means for controlling the amount of secondary air supplied to the exhaust gas purification device, wherein when the pump loss reduction device is activated, the amount of secondary air supplied to the exhaust gas purification device is The present invention is characterized in that it is provided with a secondary air supply amount correction means for reducing and correcting the secondary air supply amount.

Therefore, according to the present invention, in the pump loss reduction region where the intake stroke is substantially shortened, the secondary Air supply amount can be controlled.

Therefore, by shortening the intake stroke, the effective compression ratio of the engine is reduced, so even if the combustion speed decreases and the exhaust gas becomes hot due to the expansion stroke,
By reducing the secondary air supply amount itself, the combustion reaction rate on the exhaust side is reduced, and the temperature rise is suppressed within a predetermined range that does not impair the function of the exhaust purification device such as the catalytic converter. Therefore, problems like the conventional ones do not occur.

[Brief explanation of the drawing]

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 a diagram of the engine main body in the same embodiment device. 4 is a cross-sectional view showing the structure of the air control valve in the device of the same embodiment; FIG. 5 is a schematic block diagram showing the functions of the engine control unit in the device of the same embodiment; FIG. 6 is a flowchart showing the secondary air supply amount correction operation when the engine compression ratio is varied by the engine control unit, and FIGS. FIG. !・・・・・・Lower piston engine body 2.3 ・
... Trochoid space 4.5 ... Rotor housing 6.8 ... Side housing 7 ... Intermezoate housing to, tt
...Rotor I9...Exhaust pipe 21.22...Main intake boat 25...Intake recirculation passage 26...Opening/closing control valve 40...Opening/closing valve actuator 41...Duty - Solenoid 45... Air flow meter 46... Throttle valve 47... Throttle opening sensor 48... Acceleration sensor 50... Engine control unit 5I...
-First catalytic converter 52...Second catalytic converter 53...First secondary air supply nozzle 54...Second secondary air supply nozzle 55...Air pump 60. ...Secondary air main supply path 75...First solenoid valve 89...Second solenoid valve +02...Area determination circuit

Claims (1)

[Claims] 1. A pump loss reduction means that reduces pump loss by substantially shortening the intake stroke in a specific operating region, an exhaust purification device, and controls the amount of secondary air supplied to the exhaust purification device in accordance with the operating region. Secondary air supply amount correction for reducing the amount of secondary air supplied to the exhaust purification device when the pump loss reduction means is activated in the secondary air control device for the engine, which includes a secondary air supply means. A secondary air control device for an engine, characterized in that it comprises means.