JPH06221172A - Control device for engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent worsening of running performance owing to deficiency in a supercharging pressure during the feed of secondary air by a method wherein, when a part of supercharging air is fed as secondary air to an exhaust gas system, the operation starting point of a supercharger on the high speed side is shifted to the higher speed side than that during the non-feed of secondary air. CONSTITUTION:A two-cylinder (tow-rotor) rotary piston engine 1 is provided with two exhaust gas turbochargers 2 and 3 on the primary side wherein the engine is operated at least in a low rotation region and on the secondary side wherein it is run only in a high rotation region. Further, two exhaust gas passages 5 and 6 are joined with a single exhaust gas passage 9 in a position situated downstream from turbines 7 and 8 of the two superchargers 2 and 3 and connected to a silencer 11 through a catalyst converter 10. Further, an air passage 70 through which supercharging air is fed as secondary air (split air) is connected to the air port 10a of a catalyst converter 10. In this case, during the feed of secondary air, the operation starting point of the supercharger 3 on the secondary side is shifted to the higher speed side than that during the non-feed of secondary air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an engine with a supercharger, and more particularly to a low speed side supercharger operated at least in a low speed region and a high speed side supercharger operated only in a high speed region. Of a supercharger engine which is provided with a secondary air supply means for supplying a part of the supercharged air discharged from the supercharger to the exhaust system as secondary air according to the operating state of the engine. Regarding the control device.

[0002]

2. Description of the Related Art It is known that supplying secondary air to a catalytic converter provided in an exhaust system of an engine can enhance the exhaust purification performance of the catalytic converter. As disclosed in Japanese Patent Laid-Open No. 59-58115, it has been proposed to supply a part of the supercharged air discharged from the supercharger to the exhaust system as secondary air.

In a rotary piston engine, air pressurized by an air pump driven by the engine is supplied as secondary air into the exhaust port and the catalytic converter as so-called "port air" and "split air", respectively. Things are also being done.

In the case of a rotary piston engine with a turbocharger, conventionally, pressurized air from an air pump is supplied as port air only in the exhaust port, and one of the supercharged air downstream of the compressor is supplied to the catalytic converter. The part is supplied as split air.

In this case, the air pump is driven by the engine via an electromagnetic clutch that is ON / OFF controlled by a control unit, and in the middle of the air passage connecting the intake passage downstream of the compressor and the catalytic converter. In an area I shown in FIG. 6, an on-off valve controlled to be opened and closed by the control unit is provided, and the electromagnetic clutch is turned on and the on-off valve is closed to supply only port air from the air pump to the exhaust port. In the area II of 6, the electromagnetic clutch is turned off.
The air pump is stopped and the on-off valve is opened to supply a part of the supercharged air to the catalytic converter as split air.

A region III in FIG. 6 is a region where the electromagnetic clutch is turned off and the on-off valve is closed to stop the supply of secondary air.

On the other hand, as disclosed in, for example, Japanese Patent Application Laid-Open No. 1-315615, two primary and secondary exhaust turbochargers are installed in parallel in the engine, and the turbine inlet side of the secondary turbocharger is installed. A cut valve is provided in each of the exhaust passage and the intake passage on the outlet side of the compressor, and in the low engine speed region, the cut valve is closed to perform supercharging only by the primary turbocharger.
In the high engine speed region, a so-called sequential turbo engine has been proposed in which the cut valve is opened to operate both superchargers.

In such a sequential turbo engine, for example, a cut valve opening / closing control map as shown in FIG. 7 is prepared, and the cut valve is closed in the region on the left side of the curve A at the time of acceleration so that only the primary turbocharger is used. When the fuel is supplied to the region on the right side of curve A, the cut valve is opened so that supercharging is performed by both the primary and secondary turbochargers.

[0009]

By the way, in the above-mentioned sequential turbo engine, when the acceleration is as shown in FIG.
As the cut valve is opened when passing through the curve A from left to right, the supercharging pressure is temporarily reduced as shown by the solid line a in FIG.

Therefore, when the engine is provided with the secondary air supply means for supplying a part of the supercharging pressure discharged from the compressor to the catalytic converter and the secondary air supply means is in operation, As indicated by the broken line a ′ in FIG. 8, the supercharging pressure is further reduced, and there is a problem that the running performance of the vehicle is deteriorated during sudden acceleration.

In view of the above circumstances, the present invention comprises at least a low speed supercharger which is operated in a low rotation range and a high speed supercharger which is operated only in a high rotation range. In a supercharged engine equipped with a secondary air supply means for supplying a part of the supercharged air discharged from the exhaust air to the exhaust system as secondary air according to the operating state of the engine, the secondary air supply means operates. It is an object of the present invention to provide a control device for an engine with a supercharger, which prevents deterioration of traveling performance due to insufficient supercharging pressure.

[0012]

According to the present invention, there is provided a control device for an engine with a supercharger in which a secondary air supply means for supplying a part of supercharged air discharged from the supercharger to an exhaust system is in operation. ,
The present invention is characterized by comprising control means for shifting the operation start point of the high speed side turbocharger to a higher speed side than when the secondary air supply means is not operating.

Specifically, the control means has a first control map showing the operation start characteristic of the high speed side turbocharger when the secondary air supply means is not operating, and the operation start of the high speed side turbocharger. High speed according to a second control map in which the operation start characteristic whose point is shifted to a higher rotation side than in the first control map is represented as the operation start characteristic of the high speed side supercharger when the secondary air supply means is in operation. It controls the side turbocharger.

Alternatively, the control means starts the operation of the high speed side supercharger during the operation of the secondary air supply means.
The secondary air supply means is delayed by a predetermined time compared to when it is inactive.

[0015]

According to the present invention, as shown in FIG. 2, the operation start characteristic of the high speed side turbocharger represents the operation start characteristic of the high speed side turbocharger when the secondary air supply means is not operated. The curve A is shifted to the curve B when the secondary air supply means is activated.

Therefore, as indicated by a broken line b in FIG. 3 corresponding to FIG. 8, the amount of decrease in the supercharging pressure is reduced, and it is possible to prevent the running performance from deteriorating during sudden acceleration.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall system diagram of an embodiment of the present invention, which is a two cylinder (two rotor) rotary piston engine 1
Is equipped with two exhaust turbochargers 2, 3 on the primary side and the secondary side.

Exhaust passages 5 and 6 connected to an exhaust port 4 formed in the rotor housing 1a of each cylinder are provided independently of each other, and one of the exhaust passages 5 is provided with a primary turbocharger 2. A turbine 7 is provided, and a turbine 8 of the secondary turbocharger 3 is provided in the other exhaust passage 6.

The two exhaust passages 5, 6 are connected to both turbines 7,
8 merges with one exhaust passage 9 downstream, and is connected to a silencer 11 via a catalytic converter 10. The catalytic converter 10 has an air port 10a to which secondary air is supplied.

The intake passage 13 downstream of the air cleaner 12 is branched into two, and the compressor 15 of the primary turbocharger 2 is arranged in the middle of the first branch passage 14 of the second branch passage 16. A compressor 17 of the secondary turbocharger 3 is arranged on the way.

The branch passages 14 and 16 are formed so as to face each other at the branch portion and extend substantially straight on both sides. Further, the two branch passages 14 and 16 merge again downstream of the compressors 15 and 17 into one intake passage 18, and an intercooler 19 is arranged in the intake passage 18.
A surge tank 20 is arranged downstream thereof. Also,
A throttle valve 21 is arranged between the intercooler 19 and the surge tank 20.

The downstream end of the intake passage 18 is branched to form the engine 1
The two independent passages 22 and 23 corresponding to each cylinder are connected to each intake port 24. Two fuel injection valves 25 and 26 are arranged in series in the independent intake passages 22 and 23, respectively.

The two exhaust passages 5 and 6 are located upstream of both the primary and secondary turbochargers 2 and 3.
The communication passages 27 communicate with each other. An exhaust cut valve 28 is provided immediately downstream of the opening position of the communication passage 27 in the exhaust passage 6 in which the secondary turbine 8 is arranged. The exhaust cut valve is linked to a diaphragm type actuator 29. ing.

Further, in the exhaust passage 5 in which the primary-side turbine 7 is arranged, a bypass passage 30 that communicates with a combined exhaust passage 9 from immediately upstream of the turbine 7 to downstream of the turbines 7 and 8 is provided.
And a wastegate valve 32 linked to a diaphragm type actuator 31 is formed in the bypass passage 30.
Is provided.

Further, a leak passage 33 connecting the communication passage 27 and the downstream side of the exhaust cut valve 28 of the exhaust passage 6 in which the secondary turbine 8 is arranged is extended from the middle of the communication passage 27, and the leak passage 33 An exhaust leakage valve 35 linked to a diaphragm type actuator 34 is provided therein.

On the other hand, in the branch passage 16 in which the compressor 17 of the secondary turbocharger 3 is arranged, the compressor 17
An intake cut valve 36 is arranged at a downstream position of the. The intake cut valve 36 is a butterfly valve and is linked to a diaphragm actuator 37. Further, a relief passage 38 is formed in the secondary side branch passage 16 so as to bypass the compressor 17, and an intake relief valve 39 integrally provided with a diaphragm type actuator 48 is arranged in the relief passage 38. There is.

Actuator for operating the exhaust leakage valve 35
The pressure chamber 34 communicates with the downstream side of the compressor 15 in the branch passage 14 in which the compressor 15 of the primary turbocharger 2 is arranged, through a conduit 40. Then, when the pressure on the downstream side of the compressor 15 becomes equal to or higher than a predetermined value, the actuator 34 operates to open the exhaust leakage valve 35, whereby a small amount of exhaust gas is released when the exhaust cut valve 28 is closed. The secondary turbocharger 3 is supplied to the secondary side turbine 8 through the leak passage 33.
Rotation is started in advance before the exhaust cut valve 28 is opened. During this time, the intake relief valve 39 is opened, whereby the rotation of the secondary turbocharger 3 rises, thereby improving the transient response when the exhaust cut valve 28 is opened, and alleviating the torque shock. .

Actuator for operating the intake cut valve 36
37 has two pressure chambers divided by its diaphragm, the first of which is provided with the spring.
The pressure chamber of is connected to the output port of the electromagnetic solenoid type three-way valve 42 through the conduit 41. The second pressure chamber is connected to the downstream side of the intake cut valve 36 of the intake passage 16 through the conduit 43 so that the boost pressure P1 on the downstream side of the primary side compressor 15 is introduced into the second pressure chamber. ing.

Note that the valve bodies of the six electromagnetic solenoid type three-way valves shown in FIG. 1 all represent positions in the OFF state (non-excited state).

Actuator for operating the exhaust cut valve 28
29 is provided with two pressure chambers partitioned by a diaphragm, the first pressure chamber on the side provided with the spring is connected to the output port of the electromagnetic solenoid type three-way valve 45 through the conduit 44, and the second pressure chamber is connected. Is connected to the output port of an electromagnetic solenoid type three-way valve 47 through a conduit 46.

On the other hand, the pressure chamber of the diaphragm type actuator 48 integrally formed with the intake relief valve 39 is connected to the output port of the electromagnetic solenoid three-way valve 50 through the conduit 49. The intake relief valve 39 keeps the relief passage 38 open until a predetermined time before the exhaust cut valve 28 and the intake cut valve 36 are opened, and the secondary turbocharger 3 is pre-rotated by the exhaust gas supplied through the leak passage 33. At this time, the rotation of the compressor 17 is increased while suppressing the pressure upstream of the intake cut valve 36 from increasing to the surging region.

The pressure chamber of the actuator 31 for operating the wastegate valve 32 is connected to the output port of the electromagnetic solenoid type three-way valve 52 through the conduit 51.

One input port of the three-way valve 42 for controlling the intake cut valve 36 is connected to the negative pressure tank 54 through the conduit 53, and the other input port is upstream of the intake cut valve 36 in the intake passage 16 through the conduit 55. It is connected to the. In the negative pressure tank 54, the intake negative pressure downstream of the throttle valve 21 is checked by a check valve.
Introduced via 56.

Two three-way valves 45 for controlling the exhaust cut valve 28,
Of the 47, one input port of the first three-way valve 45 is connected through a conduit 57 in the middle of the conduit 53 connected to the negative pressure tank 54, and the other input port is open to the atmosphere. Also, one input port of the second three-way valve 47 is a conduit
It is connected to the air tank 59 through 58, and the other input port is open to the atmosphere. The air tank 59 is connected to the intake passage 18 via a check valve 60.

One input port of the three-way valve 50 for controlling the intake relief valve 39 is connected through a conduit 61 in the middle of a conduit 53 connected to the negative pressure tank 54, and the other input port is open to the atmosphere. .

One input port of the three-way valve 52 for controlling the wastegate valve 32 is open to the atmosphere, and the other input port is connected to the intake passage 14 downstream of the primary side compressor 15 through a conduit 62.

The above five electromagnetic solenoid type three-way valves 42, 4
5, 47, 50 and 52 are turned on by the control unit 100 that is configured using a microcomputer.
It is turned off.

Intake cut valve 36 Actuator 37 for operating
In the OFF state of the three-way valve 42, since the negative pressure is supplied to the first pressure chamber connected to the output port of the three-way valve 42 through the conduits 53 and 41, the intake cutoff valve 36 is closed.

When the three-way valve 42 is turned on, the intake cut valve 36
When the intake valve is closed, the pressure on the upstream side of the intake cut valve 36, that is, the supercharging pressure P2 of the secondary side compressor 17 is introduced into the second pressure chamber of the actuator 37, and this pressure P2
And a difference (P2-P1) between the boost pressure P1 on the downstream side of the primary-side compressor 15 introduced into the first pressure chamber of the actuator 37 becomes larger than a predetermined value, the actuator 37 is activated to cut the intake air. It is configured to open valve 36.

When the first and second three-way valves 45, 47 for controlling the exhaust cut valve 28 are off, the conduits 44, 46 are passed through the first and second pressure chambers of the actuator 29 for operating the exhaust cut valve 28, respectively. Atmospheric pressure is introduced, and the exhaust cut valve 28 is closed, but the three-way valves 45 and 47 are both O.
When N, the conduit 44 is connected to the first pressure chamber of the actuator 29.
Negative pressure is introduced through the second pressure chamber and conduit 58
By introducing the positive pressure in the intake passage 18 through 46 and 46, the exhaust cut valve 28 is opened, and supercharging by the secondary turbocharger 3 is started.

The three-way valve 50 for controlling the intake relief valve 39 is OF
When F, an actuator for operating the intake relief valve
The intake relief valve 39 is opened by the introduction of negative pressure into the pressure chamber of 48 through the conduits 61 and 49, and the three-way valve 50
When is turned on, atmospheric pressure is introduced into the pressure chamber of the actuator 48 through the conduit 49, so that the intake relief valve
39 is closed.

The actuator 31 for operating the wastegate valve 32 operates by positive pressure by communicating with the downstream of the primary side compressor 15 through the conduits 51 and 62 when the three-way valve 52 for controlling the wastegate valve 32 is ON. Then, the waste gate valve 32 is opened.

In this embodiment, the opening / closing operations of the exhaust cut valve 28, the intake cut valve 36 and the intake relief valve 39 are all provided with hysteresis. Further, in order to prevent the intake backflow to the secondary side compressor 17 when the state where the exhaust cut valve 28 is closed and the intake cut valve 36 remains open during the shift from the high intake air amount side to the low intake air amount region, In this region, the intake cut valve 36 is forcibly closed after a predetermined time (for example, 2 seconds) has elapsed since the exhaust cut valve 28 was closed.

On the other hand, an air passage 70 for supplying supercharged air as secondary air (split air) to the catalytic converter 10 connects the intake passage 18 upstream of the intercooler 19 and the air port 10a of the catalytic converter 10. An opening / closing valve 72 integrally provided with a diaphragm type actuator 71 is arranged in the air passage 70.

The pressure chamber of the actuator 71 is a conduit 73.
Through an electromagnetic solenoid type three-way valve 74. One input port of the three-way valve 74 is connected to the surge tank 20 through the conduit 75, and the other input port is open to the atmosphere.

Therefore, when the three-way valve 74 is OFF, the opening / closing valve 72 closes the air passage 70, and the three-way valve 74 is turned off.
When it becomes N, the intake negative pressure is introduced into the pressure chamber of the actuator 71 through the conduits 75 and 73, and the on-off valve 72 opens the air passage.
To open 70, supercharged air is supplied to the air port 10a of the catalytic converter 10 as secondary air (split air). The on-off valve 72 and the catalytic converter 10
A check valve 76 is provided in an air passage 70 between the check valve 77 and the check valve 77, and a check valve 77 is also provided midway in the conduit 75.

Further, the rotor housing 1a of the engine 1
An air port 78 that opens to the exhaust port 4 is provided in the. An air passage 79 is provided to take out air from the air cleaner 12 and supply secondary air (port air) to the air port 78. The air passage 79 is driven by the engine 1 via the electromagnetic clutch 80 in the middle of the air passage 79. An air pump 81 is provided. A valve device 82 having an opening / closing valve controlled by an electromagnetic solenoid valve is provided on the downstream side of the air pump 81 in the air passage 79.

A throttle opening sensor 85 for detecting the opening (TVO) of the throttle valve 21, a pressure sensor 86 for detecting the intake pressure (boost) in the surge tank 20,
A crank angle sensor 87 for detecting the engine speed and an O ₂ sensor 88 for detecting the oxygen concentration in the exhaust passage 9 upstream of the catalytic converter 10 are provided. The outputs of these sensors 85 to 88 are supplied to the control unit 100.

In FIG. 4, the exhaust cut valve 28 and the intake cut valve 36 are opened during acceleration to open the secondary turbocharger 3.
6 is a flowchart showing an example of a control routine in which the control unit 100 turns on the three-way valves 42, 45, 47 in order to operate the.

The control unit 100 stores a first control map represented by the curve A of FIG. 2 and a second control map represented by the curve B of FIG. 2 for the operation start characteristics of the secondary turbocharger 3. Has been done.

The initial condition is that the electromagnetic clutch 80 is ON.
(Air pump 81 operates), three-way valve 74 is OFF (open / close valve 72
Is closed).

First, in step S1 of FIG. 4, the engine speed, boost and throttle opening are read from the outputs of the crank angle sensor 87, the pressure sensor 86 and the throttle opening sensor 85. And step S2
Then, the current operating region is checked according to the map of FIG.
The control map (curve A in FIG. 2) is read, and in the next step S4, it is checked according to the first control map whether or not the operation start condition of the secondary turbocharger 3 is satisfied, and the determination in step S4 is “YES”. When it becomes ", step S5
Then, the three-way valves 42, 45 and 47 are turned on to operate the secondary turbocharger 3.

In the next step S2, when it is determined that the current operation area is in the area II in FIG. 6, the electromagnetic clutch 80 is turned off to stop the air pump 81 in step S6, and the supply of the port air is stopped. At the same time, in step S7, the three-way valve 74 is turned on to open the on-off valve 72, and the secondary air is supplied from the intake passage 18 to the catalytic converter 10 as split air.

Next, in step S8, it is checked from the changing state of the throttle opening whether or not there is rapid acceleration, and if not sudden acceleration, the process proceeds to step S3 to perform control according to the first control map.

On the other hand, if it is determined in step S8 that the acceleration is rapid, the second control map (curve B in FIG. 2) is read in step S9, and the determination in step S4 is made in accordance with the second control map. And the process of step S5 is performed.

As described above, in this control routine, the first control map showing the operation starting characteristic of the secondary turbocharger 3 when the supercharged air is not supplied to the catalytic converter 10, and the secondary turbocharger are shown. The operation start point of No. 3 is shifted to a higher rotation side than in the first control map, and the operation start characteristic is shifted to the secondary turbo at the time of rapid acceleration in a region where the supercharged air is supplied to the catalytic converter 10 as split air. By controlling the secondary turbocharger 3 in accordance with the second control map showing the operation start characteristic of the supercharger 3, it is possible to prevent deterioration of traveling performance due to insufficient supercharging pressure during sudden acceleration. .

Next, FIG. 5 is a flow chart showing another example of the control routine executed by the control unit 100. In this control routine, the supercharged air is the catalytic converter 10
At the time of sudden acceleration in the region where the secondary turbocharger 3 is supplied to the engine, a timer is used to delay the start of operation of the secondary turbocharger 3 by a predetermined time. In this case, the control map shown in FIG. 7 is stored in the control unit 100.

That is, in step S11 of FIG. 5, the engine speed, boost and throttle opening are read from the output of each sensor, and in the next step S12, it is determined whether the current operating region is within the region II of FIG. judge.

If it is determined in step S12 that the current operating region is the region I or III in FIG. 6, the process proceeds to step S13 and the secondary turbocharger 3 is operated according to the control map in FIG.
It is checked whether or not the operation starting condition of is satisfied, and step S13
When the determination is "YES", the process proceeds to step S14, the three-way valves 42, 45 and 47 are turned on to operate the secondary turbocharger 3.

Next, when it is determined in step 12 that the current operating region is in the region II of FIG. 6, the electromagnetic clutch 80 is turned off in steps S15 and S16 as in steps S6 and S7 of FIG. Then, the air pump 81 is stopped to stop the supply of the port air, and at step S16, the three-way valve 74 is turned on to open the opening / closing valve 72, and the secondary air is supplied from the intake passage 18 to the catalytic converter 10 as split air.

In the next step S17, it is checked whether or not the operation starting condition of the secondary turbocharger 3 is satisfied according to the control map of FIG. 7, and the determination in step S17 is "YES".
When it becomes, it progresses to step S18 and it is checked whether it is a rapid acceleration.

If the determination in step S18 is "NO",
In step S14, the three-way valves 42, 45 and 47 are turned on to start the operation of the secondary turbocharger 3. If the determination in step S18 is "YES", the timer counter is started in step S19. In the next step S20, checks whether a predetermined time T ₀ from the start of the timer counter has elapsed, the determination in step S20 is "NO"
While it is, the timer counter is incremented in step S21. When the determination in step S20 becomes "YES", the process proceeds to step S14, and the three-way valves 42, 45 and 47
Is turned on to operate the secondary turbocharger 3.

It is apparent that the control routine as described above can prevent the deterioration of the traveling performance due to the insufficient boost pressure at the time of sudden acceleration.

[Brief description of drawings]

FIG. 1 is an overall system diagram of an embodiment of the present invention.

FIG. 2 is a control map showing the operation start characteristics of the secondary turbocharger.

FIG. 3 is a graph for explaining the effect of the present invention.

FIG. 4 is a flowchart showing an example of a control routine.

FIG. 5 is a flowchart showing another example of a control routine.

FIG. 6 is a map showing an engine operating region

FIG. 7 is a control map showing the operation start characteristics of the secondary turbocharger in the conventional turbocharged engine.

FIG. 8 is a graph for explaining the same action.

[Explanation of symbols]

 1 rotary piston engine 2 primary turbocharger 3 secondary turbocharger 4 exhaust port 10 catalytic converter 28 exhaust cut valve 36 intake cut valve 42, 45, 47, 50, 52, 74 electromagnetic solenoid three-way valve 80 electromagnetic clutch 81 air pump 100 control unit

Front page continuation (72) Inventor Manabu Mukai 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Motor Corporation

Claims (3)

[Claims] 1. A low-speed supercharger that operates at least in a low rotation range and a high-speed side supercharger that operates only in a high rotation range, and provide supercharged air discharged from the supercharger. In a supercharged engine equipped with a secondary air supply means for supplying a part of the air to the exhaust system as secondary air according to the operating state of the engine, the high-speed side engine is operated while the secondary air supply means is operating. A control device for an engine with a supercharger, comprising control means for shifting the operation start point of the feeder to a higher speed side than when the secondary air supply means is not operating. 2. The first control map, which represents the operation start characteristic of the high speed side turbocharger when the secondary air supply means is not operating, and the operation start point of the high speed side turbocharger. According to a second control map in which the operation start characteristic shifted to a higher rotation side than in the first control map is represented as the operation start characteristic of the high speed side supercharger during the operation of the secondary air supply means. The control device for an engine with a supercharger according to claim 1, wherein the supercharger on the high speed side is controlled. 3. The control means delays the start of operation of the high speed side supercharger during the operation of the secondary air supply means by a predetermined time compared to when the secondary air supply means is inactive. The control device for the engine with a supercharger according to claim 1.