JP2795696B2 - Control device for supercharged engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an engine with a supercharger provided with a plurality of superchargers, wherein a part of the exhaust turbocharger is operated only in a specific operation region. Related to a control device.

2. Description of the Related Art Conventionally, as a turbocharged engine having two exhaust turbochargers, for example, as disclosed in Japanese Utility Model Laid-Open Publication No. 60-178329, primary and secondary exhaust turbochargers are provided in an exhaust passage. Turbocharger turbines are provided in parallel, the blowers of the two exhaust turbochargers are connected to the intake passage of the engine, and an exhaust cut valve is provided in the exhaust passage upstream of the turbine of the secondary turbocharger. In the low intake air amount range where the intake air amount is smaller than the set value, the exhaust cut valve is closed to disable the secondary turbocharger, and the exhaust gas from the exhaust passage is intensively supplied to the turbine of the primary turbocharger In the high intake air amount range where the intake air amount is larger than the set value, the exhaust cut valve is opened and the secondary turbocharger is operated to secure a high supercharging pressure. The air gas so as to obtain a proper boost pressure while supplying the turbine of the two exhaust turbochargers ensure an intake air quantity, is known sequential turbo engine.

(Problems to be Solved by the Invention) In such an engine with a supercharger, an intake cutoff valve is provided in an intake passage dedicated to the secondary turbocharger, and a low intake air amount region in which the secondary turbocharger does not operate. Then, this intake cut valve is closed to prevent the pressurized air downstream of the primary side blower from flowing back to the secondary side blower.

However, if the intake cut valve is closed due to failure and the exhaust cut valve is opened due to a high intake air volume range, the secondary side blower downstream of the secondary side blower is closed by the intake cut valve. As the side blower rotates, this secondary side blower surgings,
The reliability of the secondary turbocharger is impaired.

The present invention has been made in view of such a point, and an object thereof is to avoid the surging of the secondary side blower by disabling the secondary turbocharger when the intake cut valve fails. It is in.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, when the intake cut valve is closed in a high intake air amount range where the secondary turbocharger operates, the operation of the secondary turbocharger is performed. They are banned.

Specifically, a solution means taken in the invention of claim 1 is to provide a plurality of superchargers including an exhaust turbocharger in an intake passage having first and second branch passages connected in parallel to each other. Arranged in parallel, at least one of the superchargers is a primary supercharger disposed in the first branch passage, and at least one exhaust turbocharger is disposed in the second branch passage. It is assumed that the engine is a secondary turbocharger that is disposed, and an engine with a turbocharger that operates the secondary turbocharger only in a high intake air amount range.

On the other hand, an intake cut valve disposed in a second branch passage downstream of the blower of the secondary turbocharger and closed in a low intake air amount region other than the high intake air amount region; An intake relief passage branched and connected to a second branch passage upstream of the intake cut valve downstream of the blower and having an intake relief valve for relieving air downstream of the blower of the secondary turbocharger; An exhaust cut valve arranged in an exhaust passage on the upstream side of a turbine of the feeder, wherein when the engine shifts from a low intake air amount region to a high intake air amount region, the intake relief valve is closed, and the exhaust cut valve is closed. After the valve is opened, when the supercharging pressure on the downstream side of the blower of the secondary turbocharger rises and the difference with the supercharging pressure by the primary supercharger disappears, the intake cut valve is opened. Configured to be a valve.

Further, an operating state detecting means for detecting an operating state of the intake cut valve, and an output of the operating state detecting means,
When the intake cutoff valve is closed in the high intake air amount range, a supercharger control means for prohibiting the operation of the secondary turbocharger is provided.

Here, in the invention of claim 2, in claim 1, the plurality of superchargers are set as two primary and secondary exhaust turbochargers, and the primary turbocharger is set in a low intake air amount region and a high intake turbocharger region. It is operated in the intake air amount range, and the secondary turbocharger is operated only in the high intake air amount region.

(Operation) According to the first and second aspects of the present invention, when the engine shifts from the low intake air amount region to the high intake air amount region, first, the intake relief valve is closed, and the secondary turbocharger is operated. The air downstream of the blower is not relieved by the relief passage. Further, after the exhaust cut valve is opened and the exhaust passage on the upstream side of the turbine of the secondary turbocharger is opened, the supercharging pressure on the downstream side of the blower of the secondary turbocharger increases, and When the difference between the supply pressure and the supercharge pressure by the primary supercharger is reduced, the intake cut valve is opened, and the secondary turbocharger and the second branch passage downstream of the blower are opened. As described above, when the engine shifts from the low intake air amount region to the high intake air amount region,
By closing the intake relief valve, the supercharging pressure of the secondary turbocharger is increased, and when the pressure difference between this supercharging pressure and the supercharging pressure of the primary turbocharger decreases, the intake cut valve is opened to switch at the time of switching. The supercharging pressure of the primary turbocharger is absorbed by the blower side of the secondary turbocharger, and the supercharging pressure of the primary turbocharger is increased as in the case of opening the exhaust cut valve with the intake relief valve open. The supply pressure returns from the intake relief passage to the intake passage upstream side, and the engine output does not decrease due to the temporary decrease in the supercharging amount to the engine, and it is possible to prevent the engine output from temporarily decreasing due to switching. .

Further, after the transition from the low intake air amount region side of the engine to the high intake air amount region as described above, whether or not the intake cut valve is closed in the high intake air amount region is detected by the operating state detecting means. When the intake cut valve is closed based on the detection, the operation of the secondary turbocharger is prohibited by the supercharger control means. Therefore, even if the intake cut valve fails and closes in the high intake air amount range, the secondary side blower does not cause surging, and the reliability of the secondary turbocharger is improved.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a two-rotor type rotary piston engine with a turbocharger provided with a control device according to an embodiment of the present invention. In FIG. 1, reference numeral 201 denotes an engine, and exhaust passages 202 and 203 of each cylinder are provided independently of each other. The turbine 205 of the primary turbocharger 204 is disposed in one of the two exhaust passages 202 and 203, and the turbine 207 of the secondary turbocharger 206 is disposed in the other. That is, in this engine 201, the exhaust passages 202 and 203 of each cylinder are independently controlled by the turbine 2 of the primary and secondary exhaust turbochargers 204 and 206.
By leading to 05,207, a dual exhaust turbocharger 204,206
Exhaust dynamic pressure in the supercharging area by both turbines 205, 20
7 to improve the supercharging efficiency. The two exhaust passages 202 and 203 are connected to both turbines 205 and 207.
Into a single exhaust passage 224.

In addition, the intake passage 209 is divided into two downstream of an air cleaner (not shown), a blower 211 of the primary turbocharger 204 is provided in the middle of the first branch passage 210, and is provided in the middle of the second branch passage 212. Is provided with a blower 213 of a secondary turbocharger 206. These branch passages 210, 212
They are formed so as to face each other at the branching portion and extend substantially straight on both sides. Also, the two branch passages 210 and 212
Join again downstream of each blower 211,213. An intercooler 214 is disposed in the single intake passage 209 again, and a surge tank 215 is disposed downstream of the intercooler 214. A throttle valve 216 is disposed between the intercooler 214 and the surge tank 215. Has been established. The downstream end of the intake passage 209 branches into two independent intake passages 217 and 218 corresponding to each cylinder of the engine 201, and is connected to each intake port (not shown). And, each of these independent intake passages 217, 21
8 are provided with fuel injection valves 219 and 220, respectively.

An air flow meter 221 for detecting the amount of intake air is provided upstream of the intake passage 209 at a position upstream of the first and second branch passages 210 and 212.

The two exhaust passages 202 and 203 are communicated with each other by a relatively small-diameter communication passage 222 upstream of both the primary and secondary turbochargers 204 and 206. The exhaust passage 2 in which the secondary turbine 207 is disposed
In 03, an exhaust cut valve 223 is provided immediately downstream of the opening position of the communication passage 222.

Further, the turbines 205, 2
07 A wastegate passage 225 communicating with the merged exhaust passage 224 downstream is provided. In the wastegate passage 225, a wastegate valve 227 to which a diaphragm-type actuator 226 is linked is provided.

Further, a leakage passage 228 is provided for communicating the upstream portion of the wastegate valve of the wastegate passage 225 with the exhaust cut valve downstream of the exhaust passage 203 connected to the secondary turbine 207. The exhaust leak passage 228 is provided with an exhaust leak valve 230 linked to a diaphragm type actuator 229.

The exhaust cut valve 223 is a diaphragm type actuator 2
It is linked to 31. This exhaust cut valve 223 is
The so-called normally closed type is set. That is, when the engine is not operating, it is closed by receiving the spring force of the actuator 231, and when the engine is operating, it is opened by receiving the operating force of the actuator 231 that has been turned ON. This prevents exhaust gas from flowing into secondary turbocharger 206 when exhaust cut valve 223 fails. The actuator 231 includes:
Position sensor 2 that detects the opening of exhaust cut valve 223
55 are provided.

On the other hand, an intake cut valve 232 is provided downstream of the blower 213 in the branch passage 212 where the blower 213 of the secondary turbocharger 206 is provided. The intake cut valve 232 is formed of a butterfly valve, and is linked to a diaphragm type actuator 233. This intake cut valve 232
Is set to a so-called normally closed type. That is, when the engine is not operating, the actuator 23
Closed by the spring force of 3, ON when the engine is running
It is configured to open by receiving the actuation force of the actuated actuator 233. The actuator 233 is provided with a position sensor 256 for detecting the opening of the intake cut valve 232. The position sensor 256 functions as operating state detecting means for detecting the operating state of the intake cut valve 232.

In addition, a blower 213 is provided in the branch passage 212 on the secondary side.
A relief passage 234 is provided so as to bypass the diaphragm, and a diaphragm type actuator 2 is provided in the relief passage 234.
An intake relief valve 235 linked to 41 is provided. In the relief passage 234, a first pressure sensor 257, in which an intake relief valve 235 detects an intake pressure upstream,
A second pressure sensor 25 for detecting the pressure of the pressurized air on the downstream side
8 are provided respectively.

The pressure chamber of the actuator 229 that operates the exhaust leak valve 230 is connected to the primary turbocharger 2 via a conduit 236.
The blower 211 of 04 is connected to the downstream of the blower 211 of the branch passage 210 provided. When the pressure on the downstream side of the blower 211 becomes equal to or higher than a predetermined value, the actuator 229 operates to open the exhaust leak valve 230, whereby a small amount of exhaust gas is exhausted when the exhaust cut valve 223 is closed. The gas flows through the leakage passage 228 and is supplied to the turbine 207 on the secondary side. Therefore, the secondary turbocharger 206 starts rotating before the exhaust cut valve 223 opens.

The pressure chamber of the actuator 233 that operates the intake cut valve 232 is connected by a conduit 237 to the output port of an electromagnetic solenoid type three-way valve 238. Also, the exhaust cut valve 223
Is connected to the output port of another three-way valve 240 of the electromagnetic solenoid type via a conduit 239. Further, the pressure chamber of the actuator 241 that operates the intake relief valve 235 is connected by a conduit 242 to the output port of another three-way valve 243 of an electromagnetic solenoid type.
The intake relief valve 235 keeps the relief passage 234 open until a predetermined time before the exhaust cut valve 223 and the intake cut valve 232 open. Thereby, when the secondary turbocharger 206 is pre-rotated by the exhaust gas flowing through the exhaust leakage passage 228, the air is circulated to the blower 213 of the secondary turbocharger 206, and the temperature of the blower 213 is prevented from increasing, This prevents the pressure upstream of the intake cut valve 232 from rising and entering the surging region.

The actuator 226 for operating the wastegate valve 227 is connected to an output port of another three-way valve 245 of an electromagnetic solenoid type by a conduit 244.

Above four solenoid three-way solenoid valves 238,240,243,245
The two fuel injection valves 219 and 220 are controlled by a control unit 246 configured using a microcomputer. The control unit 246 includes an output signal of the engine speed sensor, an output signal of the air flow meter 221, an output signal of the position sensors 255 and 256,
In addition to the output signals of the second pressure sensors 257 and 258, the throttle opening, the supercharging pressure P1 downstream of the primary-side blower 211, and the like are input.

One input port of the electromagnetic solenoid type three-way valve 238 for controlling the intake cut valve 232 is connected to a negative pressure tank 248 via a conduit 247, and the other input port is connected to a differential pressure detection valve described later via a conduit 249. Connected to 250 output ports 270. The intake negative pressure downstream of the throttle valve 216 is introduced into the negative pressure tank 248 via a check valve 251.

Further, one input port of the three-way valve 240 for controlling the exhaust cut valve is open to the atmosphere, and the other input port is connected to the conduit 247 connected to the negative pressure tank 248 via the conduit 252. It is connected.

On the other hand, one input port of the three-way valve 243 for controlling the intake relief valve 235 is connected to the negative pressure tank 248, and the other input port is open to the atmosphere. One input port of the three-way valve 245 for controlling the wastegate valve 227 is open to the atmosphere, and the other input port is connected to the conduit 236 by a conduit 254.

As shown in FIG. 2, the differential pressure detecting valve 250 has a casing 261 in which two first and second diaphragms 26 are provided.
It is divided into three rooms 264,265,266 by 2,263.
In the first chamber 264 at one end thereof, a first input port 267 is opened, and a compression spring 268 is disposed between the inner surface of the end of the casing 261 and the first diaphragm 262. . A second input port 269 is opened in the middle second chamber 265, an output port 270 is provided in the center of the end wall of the casing 261, and a third input port 269 is provided in the third chamber 266 on the other end side. The atmosphere opening port 271 is open. And the first
Has a valve body that extends through the second diaphragm 263 and extends toward the output port 270 of the third chamber 266.
272 are fixed.

As shown in FIG. 1, the first input port 267 is connected to the downstream side of the intake cut valve 232 by a conduit 273, and the supercharging pressure P1 downstream of the primary blower 211 is supplied to the first chamber 264.
To be introduced. Also, the second input port 269 is connected to the intake cut valve 232 upstream by the conduit 274, and thus introduces the pressure P2 upstream of the intake cut valve 232 when the intake cut valve 232 is closed. I have. When the difference (P2−P1) between the pressures P1 and P2 introduced from the two input ports 267 and 269 exceeds a predetermined value, the valve element 272 opens the output port 270. The output port 270 is connected to the intake cut valve 23 via a conduit 249.
It is connected to one of the input ports of a three-way valve 238 for control. Therefore, in a state where the three-way valve 238 is ON and the conduit 237 is connected to the conduit 249 connected to the output port of the differential pressure detection valve 250 while connecting to the pressure chamber of the actuator 233 for operating the intake cut valve 232, the intake cut valve is 232 The upstream pressure, that is, the supercharging pressure P2 on the secondary side approaches the supercharging pressure P1 on the primary side, the differential pressure P1−P2 disappears, and the differential pressure P2−P1
Is larger than a predetermined value, air is introduced into the actuator 233, and the intake cut valve 232 is opened. Also,
When the three-way valve 238 is turned off and the conduit 237 on the actuator 233 side communicates with the conduit 247 connected to the negative pressure tank 248, a negative pressure is supplied to the actuator 233,
The intake cut valve 232 is closed.

On the other hand, when the three-way valve 240 for controlling the exhaust cut valve 233 is turned off and the actuator 231 for operating the exhaust cut valve 233 connects the conduit 239 leading to the pressure chamber to the conduit 252 on the negative pressure tank 248 side. The actuator 231 is closed by being supplied with a negative pressure. When the three-way valve 240 is turned on to open the output-side conduit 239 to the atmosphere, the exhaust cut valve 223 is opened, and supercharging is performed by the secondary turbocharger 206.

When the three-way valve 243 for controlling the intake relief valve 235 is OFF and the conduit 242 is connected to the negative pressure tank 248 side while connecting to the pressure chamber of the actuator 241 for operating the intake relief valve 235, the intake relief valve 235 When the three-way valve 243 is turned ON and the conduit 242 connected to the pressure chamber of the actuator 241 is opened to the atmosphere, the valve 243 is closed.

Also, an actuator 226 for operating the waste gate valve 227
When the three-way valve 245 for controlling the wastegate valve 227 is ON, it communicates with the downstream of the primary side blower 211 via the conduits 254 and 246, and when the three-way valve 245 is OFF, it is opened to the atmosphere.

In this embodiment, hysteresis is provided for the opening and closing operations of the exhaust cut valve 223, the intake cut valve 232, and the intake relief valve 235, as described later. In addition, when shifting from the high intake air amount region to the low intake air amount region, the exhaust cut valve 223
In this region, a predetermined time (for example, 2 seconds) elapses from when the exhaust cut valve 223 is closed in order to prevent the backflow of the intake air to the secondary side blower when the exhaust cut valve 232 is closed and the intake cut valve 232 remains open. Later, the intake cut valve 232 is forcibly closed.

FIG. 3 illustrates opening / closing control of the intake cut valve 232, the exhaust cut valve 223, the intake relief valve 235, and the wastegate valve 227.
9 is a control map shown together with the opening / closing control of an exhaust gas leakage valve 230. This map is stored in the control unit 246, and based on this map, the above-described four electromagnetic solenoid type three-way valves 238, 240, 243, 245 are controlled.

When shifting from the low intake air amount region to the high intake air amount region, in a region where the engine speed R is low or the intake air amount Q is small, the intake relief valve 235 is opened and the exhaust leakage valve 230 is opened. Thus, the pre-rotation of the secondary turbocharger 206 is performed. Then, when the engine speed reaches R2 or the intake air amount reaches the line of Q2, the solenoid type three-way valve 243 for controlling the intake relief valve 235 is turned on, and the intake relief valve 235 is closed.

When reaching the line of Q4-R4, the exhaust cut valve 22
(3) The solenoid-operated three-way valve 240 for control is turned on to open the exhaust cut valve 223, and then reaches the Q6-R6 line, and the solenoid-operated three-way valve 238 for the exhaust cut valve 232 is turned on and the intake cut valve is turned on. When the 232 is opened, the supercharging by the secondary turbocharger 206 starts. In other words, it enters the supercharging region by both the primary and secondary turbochargers at the line Q6-R6.

The actuator 233 that drives the intake cut valve 232 is not controlled only by the operation of the solenoid 238,
Since the atmospheric pressure, which is a pressure source for opening the intake cut valve 232, is supplied through the differential pressure detection valve 250, the intake cut valve 2
The actual opening of 32 will be delayed relative to the operation of solenoid 238. Accordingly, the line of Q6 and R6 for turning the solenoid 238 for controlling the intake cut valve 232 from OFF to ON is set in consideration of the delay caused by the differential pressure detection valve 250, and as a result, Q6
In line R6, solenoid 240 for controlling exhaust cut valve 223 is OF
It is assumed that it is close to the lines of Q4 and R4 that turn on from F.
Also, these Q6, R6 and Q4, R4 can be made to coincide.

Conversely, when shifting from the high intake air amount region to the low intake air amount region, each solenoid type three-way valve 238, 240, 2 that controls the intake cut valve 232, the exhaust cut valve 223, and the intake relief valve 235 is provided.
Reference numeral 43 is set to have a hysteresis so as to be switched by the lines Q5-R5, Q3-R3, and Q1-R1, respectively, as shown by the broken lines in FIG. In other words, when shifting from the high intake air amount range to the low intake air amount region, when reaching the line of Q3, R3, the closing control of the exhaust cut valve 223 is performed. When the line reaches the intake cut valve 2
The closing control of the intake relief valve 23 is performed after that.
The opening control of 5 is performed. Since the intake cut valve 232 closes later than the exhaust cut valve 223, surging during transition to the low intake air amount region is prevented.

Further, in this embodiment, a line Q4 which is an ON / OFF line of the solenoid 240 for controlling the line exhaust cut valve 223 for turning on / off the solenoid type three-way valve 245 for controlling the waste gate valve 227.
−R4, Q3−R3. In FIG. 3, the broken part of each line is on a so-called no-load line or load-load line.

Therefore, in the above embodiment, the introduction of exhaust gas to the secondary turbocharger 206 is stopped when the engine is in the low intake air amount range than the line Q6-R6,
Only the primary turbocharger 204 operates, and a high boost pressure can be obtained at a good rise. On the other hand, the engine
When the air amount is higher than Q6-R6, both the primary turbocharger 204 and the secondary turbocharger 206 operate to obtain an appropriate supercharging pressure while securing the intake air flow rate.

FIG. 4 shows the relationship between the solenoid operating state of each valve and the transition of the operating state based on the characteristic diagram of FIG. 3 (the left side of the horizontal axis is a low intake air amount area, and the right side is a high intake air amount area) Is what I saw in As can be seen from this figure, the hysteresis of the opening and closing operation of the exhaust cut valve 223 is completely included in the hysteresis of the opening and closing operation of the intake cut valve 232. The intake cut valve 23
(2) Even if the control solenoid 238 is turned on at Q6 and R6, the actual opening operation of the intake cut valve 232 is delayed by the action of the differential pressure detection valve 250 as shown by the broken line in FIG. Therefore, this Q6, R
Reference numeral 6 denotes a line close to or the same as Q4 and R4 of the exhaust cut valve 223 opening control as described above. On the other hand, the closing operation of the intake cut valve 232 does not involve the delay as described above with respect to the operation of the solenoid 238, so that the setting lines Q5 and R5 need to satisfy Q5 <Q3 and R5 <R3. is there.

Next, the position sensors 255 and 256 and the pressure sensor 25
The control of the fuel injection valves 219 and 220 based on 7,258 will be described based on the flow of FIG. After starting, first step S1
Reads the engine speed, the supercharging pressure, the intake air amount, etc., and determines the current engine operating region in step S2. Next, in step S3, the operating range of the engine is either the low intake air amount region (the region where only the primary turbocharger 204 operates) or the high intake air amount region (both the primary and secondary exhaust turbochargers 204 and 206). Operating area)
Judge. When the intake air amount is in the low intake air amount range (NO), the process returns as it is, while when the intake air amount is in the high intake air amount region (YES), the process proceeds to step S4, and it is determined whether or not the intake relief valve 235 has been opened. That is, when the pressure difference between the pressures detected by the two pressure sensors 257 and 258 is equal to or less than the predetermined value, it is determined that the intake relief valve 235 is open.

Then, when it is determined that the intake relief valve 235 is left open, the fuel cut line is changed in step S7 and the routine returns. Here, this fuel cut line is usually set as shown by the solid line in FIG. 6, and the fuel injection is performed on the high rotation side or the high boost side (the area shown by oblique lines in FIG. 6). The control is performed to stop the fuel supply from the valves 219 and 220. The dashed line in the figure indicates the low intake air amount region (the primary turbocharger 204
Only in the “P region”, in which only the primary and secondary exhaust turbochargers 204 and 20 are operated.
6 is a switching line that separates the “P + S region” in which operation is performed. In step S7, as shown in FIG. 7, the fuel cut line is changed to match this switching line, and the area where fuel supply is stopped is enlarged. By this processing, the engine 201 is operated only in the low intake air amount range,
The secondary turbocharger 206 becomes inactive. As a result, it is possible to avoid the operation of the secondary turbocharger 206 in a state where the intake relief valve 235 is left open, and it is possible to prevent a problem due to a supercharging failure of the secondary-side blower 213.

On the other hand, when it is determined in step S4 that the intake relief valve 235 is closed, the process proceeds to step S5, where the exhaust cut valve 22
It is determined by the position sensor 255 whether or not 3 is closed. When it is determined that the fuel cell is to be closed, the process proceeds to step S7, and the fuel cut line is changed as described above,
The operation returns after the secondary turbocharger 206 is deactivated. As a result, it is possible to prevent the fuel from being increased in a state of insufficient supercharging, thereby preventing poor combustion.

Further, when it is determined in step S5 that the exhaust cut valve 223 is open, the process proceeds to step S6, where the intake cut valve 23
It is determined by the position sensor 256 whether or not 2 is closed. When it is determined that the fuel cell is to be closed, the process proceeds to step S7, and the fuel cut line is changed as described above,
The operation returns after the secondary turbocharger 206 is deactivated. As a result, even when the intake cut valve 232 fails and is closed, the secondary blower 213 does not cause surging, and the reliability of the secondary turbocharger 206 is improved. On the other hand, when it is determined in step S that the intake cut valve 232 is open, it is determined that there is no abnormality in each of the valves 223, 232, and 235, and the process returns.

In the above flow, the operation state detection means 301 for detecting the operation state of the intake cut valve 232 is constituted by step S6. In another step, the output of the operating state detecting means 301 is received, and the intake cut valve 2
When the valve 32 is closed, it constitutes a supercharger control means 302 for inhibiting the operation of the secondary turbocharger 206.

In this embodiment, the operating state of the intake cut valve 232 is detected based on the position sensor 256, but the operating state of the intake cut valve 232 may be detected based on the detected pressures of the two pressure sensors 257 and 258. It is possible. That is, when the exhaust cut valve 223 and the exhaust leak valve 230 are open and the intake relief valve 235 is closed, the intake cut valve 2
When the valve 32 is left closed, the pressure difference between the upstream pressure and the downstream pressure of the intake relief valve 235 increases. Therefore, by detecting the increase in the differential pressure, it can be determined that the intake cut valve 232 is in the closed state.

Further, as another method of determining that the intake relief valve 235 is left open, the rotation speed of the primary turbine 205 is detected, and when the turbine rotation speed exceeds the allowable rotation speed, the rotation is determined to be open. There is a method of determining. This method can also be used as a method for determining that the exhaust cut valve 223 is left closed. Furthermore, exhaust cut valve
Another method of determining that the 223 is in the closed state is to detect the rotational speed of the secondary turbine 207 and determine that the turbine is in the closed state when the turbine rotational speed is equal to or lower than the surging limit rotational speed. There is also.

Next, control of each valve based on the characteristics of FIG. 3 will be described with reference to the control circuit of FIG. The solenoid 243 for operating the intake relief valve is operated by the output of the first OR circuit 121 which receives the output of the first comparison circuit 111 shown at the top of the figure and the output of the second comparison circuit 112 shown below. Controlled. Here, the first comparison circuit 111 compares the intake air amount Q which is a detection signal of the air flow meter 221 with the output value of the first addition circuit 131 which is a reference value. The set value Q1 corresponding to the Q1 line in FIG. 3 is input to the first adder circuit 131, and the value of Q′1 (Q1 + Q′1 = Q2) corresponding to Q1 is set to the first value. A first gate 141 configured to be input through a gate 141;
When the first gate 141 is closed, Q1 + Q'1 = Q2 is output to the first comparison circuit 111 as a reference value, and when the first gate 141 is closed, Q1 is output to the first comparison circuit 111 as a reference value. I do. The first gate 141 is connected to the first OR
It is opened and closed by the output of the circuit 121.

The second comparison circuit 112 compares the output value of the second addition circuit 132, which is an engine speed R reference value detected by the engine speed sensor. The second adder circuit 132 receives the set value R1 corresponding to the R1 line in FIG. 3, and the value R'1 for this R1 (however,
(R1 + R'1 = R2) is input via the second gate 142, and when the second gate 142 is opened, the second comparison circuit 112 uses R1 + R'1 = R2 as a reference value.
When the second gate 142 is closed, the signal is output to the second comparison circuit 112 using R1 as a reference value. The second gate 142 is also opened and closed by the output of the first OR circuit 121.

The first and second comparison circuits 111 and 112 compare the detected intake air amount Q and the detected engine speed R with respective reference values which are outputs of the first and second addition circuits. When the value exceeds the value, an ON signal is output to the intake relief valve actuation solenoid 243 (the intake relief valve 235 is closed when turned ON). The first and second gates 141 and 142 are closed when the output signal of the first OR circuit 121 is ON, and
Opened when the R circuit signal is OFF. Therefore, when shifting from the low intake air amount range to the high intake air amount region, the first OR circuit 12
1 is OFF, the gates 141 and 142 are opened, and Q2 and R2 are supplied to the first and second comparison circuits 111 and 112 as reference values.
Is entered. Therefore, when the signal reaches the line of Q2 and R2 in FIG. 3, an ON signal is issued and the intake relief valve 235 is opened.
Also, the first and second gates 141, 14 are provided by this ON signal.
2 is closed, so that the reference values of Q and R are Q1 and R1, respectively. That is, the line is set with the hysteresis corresponding to Q'1, R'1 in preparation for the transition in the reverse direction.

The exhaust cut valve operating solenoid 240 is also controlled by a similar control circuit. That is, a third comparison circuit 113 is provided for the intake air amount Q, and a fourth comparison circuit 114 is provided for the engine speed R. The outputs of these comparison circuits 113 and 114 are provided by a second OR circuit 122. Through the solenoid
Sent to 240. A third adding circuit 133 is provided for the third comparing circuit 113, and a fourth adding circuit 133 is provided for the fourth comparing circuit 114.
Are similarly provided. The set value Q3 is input to the third adder 133, and Q'3 (where Q3 + Q'3 = Q4) is input via the third gate 143. Similarly, the fourth adder 134 has a setting value R3
And R'3 via the fourth gate 144 (where R3 + R '
3 = R4) is input. This circuit operates in the same manner as in the first and second comparison circuits, whereby the exhaust cut valve 223 is opened based on the Q4 and R4 lines in FIG. 3 when shifting to the high intake air amount range. Further, at the time of shifting to the low intake air amount range, the valve 223 is closed by the Q3 and R3 lines. Also, the waste gate valve operating solenoid 245 is simultaneously controlled by the control signal output to the exhaust cut valve operating solenoid 240.

For the solenoid 238 for operating the intake cut valve, the fifth
And a similar control circuit for supplying the outputs of the sixth comparison circuits 115 and 116 via the third OR circuit 123. This control circuit has fifth and sixth adders 135 and 136 for the respective comparators 115 and 116, and also includes adders 135 and 1
Fifth and sixth gates 145 and 146 are provided for 36. The basic operation is not different from the circuit for each valve. That is, when shifting to the high intake air volume range, Q6, R
The intake cut valve opening control is performed by the line 6 and the intake cut valve closing control is performed by the lines Q5 and R5 when shifting to the low intake air amount range. Here, Q6 and R6 are similarly Q5 +
Q'5 = Q6, R5 + R'5 = R6.

However, in the case of this intake cut valve control circuit, a seventh gate 147 is connected to the output side of the third OR circuit 123, and a control signal is sent to the solenoid 238 via the gate 147. Then, the second valve for operating the exhaust cut valve is used.
A timer 150 is provided that starts counting up when the output of the OR circuit 122 changes from ON to OFF, and
When the count value of the timer 150 exceeds a set value (for example, a value corresponding to 2 seconds), a seventh comparison circuit 11 that issues an ON signal
When an ON signal is output from the seventh comparison circuit 117, the seventh gate 147 is closed to forcibly close the intake cut valve 232, and at the same time, the reference values of Q and R are set. Q6, R
6, and the timer 150 is reset. Once the seventh gate 147 is closed,
The output of the comparison circuit 117 is OFF, but the reference value of the switching line has been changed to Q6 and R6 as described above, so that the solenoid 238 for operating the intake cut valve is kept closed. Is done. This prevents surging caused by the exhaust cut valve solenoid 238 being in the OFF state and the intake cut valve solenoid 240 being in the ON state for a long time when shifting to the low intake air amount range.

In the above embodiment, the two superchargers 204 and 206 are both exhaust turbochargers, but the present invention can be applied as long as the secondary turbocharger is an exhaust turbocharger. The supercharger other than the above may be another type, for example, a mechanical supercharger.

Further, although the rotary piston engine has been described in the above embodiment, the present invention is not limited to this. For example, the present invention can be applied to a control device of another type of supercharged engine such as a reciprocating engine. .

(Effect of the Invention) As described above, according to the control device for a supercharged engine of the inventions of the first and second aspects, the intake passage having the first and second branch passages connected in parallel with each other. A plurality of superchargers including an exhaust turbocharger are arranged in parallel, and at least one of the superchargers is a primary supercharger arranged in a first branch passage, and at least one The exhaust turbocharger is a secondary turbocharger arranged in the second branch passage, the secondary turbocharger is operated only in the high intake air amount range, and the engine is high-intake from the low intake air amount side. When shifting to the air amount range, the intake relief valve of the intake relief passage branched and connected to the second branch passage on the downstream side of the blower of the secondary turbocharger is closed,
After opening the exhaust cut valve in the exhaust passage on the upstream side of the turbine of the secondary turbocharger, the boost pressure on the downstream side of the blower of the secondary turbocharger increases, and the difference from the boost pressure by the primary turbocharger increases. Is reduced, the intake cut valve of the second branch passage downstream of the blower of the secondary turbocharger is configured to be opened. When the intake cut valve is closed in the high intake air amount range, the secondary turbocharger is closed. Since the operation of the feeder is prohibited, it is possible to open the exhaust cut valve while keeping the intake relief valve open when switching from the low intake air amount side of the engine to the high intake air amount range. While preventing the supercharging pressure of the primary turbocharger from returning from the intake relief passage to the upstream of the ventilation passage and temporarily reducing the engine output, in the high intake air amount region of the engine,
Surging of the secondary side blower when the intake cut valve has failed can be avoided to improve the reliability of the secondary turbocharger.

[Brief description of the drawings]

The drawings illustrate an embodiment of the present invention. FIG. 1 is an overall schematic configuration diagram, FIG. 2 is a cross-sectional view of a differential pressure detecting valve, FIG. 3 is a control characteristic diagram, and FIG. FIG. 5 is a flowchart for explaining the control of the control unit, and FIG.
7 and 8 are characteristic diagrams showing a fuel cut line, and FIG. 8 is a diagram showing a control circuit. 204 primary turbocharger 206 secondary turbocharger 223 exhaust cut valve 232 intake cut valve 234 relief passage 235 intake relief valve 301 operating state detecting means 302 excess Feeder control means

Claims (2)

(57) [Claims] 1. A plurality of superchargers including an exhaust turbocharger are arranged in parallel in an intake passage having first and second branch passages branched to be connected to each other. The supercharger is a primary turbocharger arranged in the first branch passage, and the at least one exhaust turbocharger is a secondary turbocharger arranged in the second branch passage, and has a high suction. In the supercharged engine in which the secondary turbocharger is operated only in the air amount range, the engine is disposed in a second branch passage downstream of the secondary turbocharger on the blower side, and the high intake air amount range An intake cut valve that is closed in a low intake air amount region other than the above, and a branch downstream of the secondary turbocharger downstream of the blower and connected to a second branch passage upstream of the intake cut valve downstream of the secondary turbocharger. An intake relief passage having an intake relief valve for relieving the air of the air, and an exhaust cut valve arranged in an exhaust passage on the upstream side of the turbine of the secondary turbocharger. When shifting to the air amount range, after the intake relief valve is closed and the exhaust cut valve is opened, the supercharging pressure on the downstream side of the blower of the secondary turbocharger rises and the supercharged pressure by the primary turbocharger increases. When the difference from the supply pressure disappears, the intake cut valve is opened, and an operation state detection means for detecting an operation state of the intake cut valve; A turbocharger control means for prohibiting the operation of the secondary turbocharger when the intake cutoff valve is closed in the intake air amount range. Down of the control device. 2. The method of claim 1, wherein a plurality of turbochargers are set as primary and secondary exhaust turbochargers, and the primary turbocharger is operated in a low intake air amount region and a high intake air amount region, and the secondary turbocharger is operated. The control device for an engine with a supercharger according to claim 1, wherein the charger is operated only in a high intake air amount range.