JPH03107528A - Control device for engine with turbosupercharger - Google Patents

Abstract

PURPOSE:To relieve torque shock by closing an exhaust air snifting valve, disposed in an exhaust air snifting passage provided at an exhaust passage on the secondary supercharger side in such a way as to by-pass an exhaust cutoff valve, forcibly during the specified period at the time of shifting from the low intake air quantity region to the high intake air quantity region. CONSTITUTION:Exhaust passages 202, 203 provided with the turbines 205, 207 of a primary and a secondary turbosuperchargers 204, 206 are mutually communicated at the upstream side of the superchargers 204, 206 by a communicating passage 222, and an exhaust cutoff valve 223 is provided on the exhaust passage 203 side. There is also provided with a snifting passage 228 for communicating the upstream part of the waste gate valve 227 of a waste gate passage 225, communicating the intermediate part of the communicating passage 222 with a combined exhaust passage 224, with the downstream part of the exhaust cutoff valve 223 of the exhaust passage 203, and a snifting valve 230 is interposed at the intermediate part of the snifting passage 228. This snifting valve 230 is controlled to be forcibly closed during the specified period after the intake air quantity exceeding the set value at the time of shifting from the low intake air quantity region to high intake air quantity region.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is provided with a plurality of exhaust turbo superchargers, and each of the exhaust turbo superchargers is operated only in a high intake air amount region of the engine. Turbo supercharger (=1)Relating to an engine control device.

(Prior Art) Conventionally, as a control device for an engine equipped with two exhaust turbo superchargers, for example, as disclosed in Japanese Utility Model Application Publication No. 178329/1983, primary and secondary exhaust turbo superchargers are installed in the exhaust passage. The turbines of the engine are installed in parallel, the blowers of these two exhaust turbo superchargers are connected to the intake passage of the engine, and an exhaust cut valve is installed upstream of the supercharger in the exhaust passage dedicated to the secondary turbo supercharger. In a low intake air volume range where the intake air volume is less than the set value, the exhaust cut valve is closed and the secondary turbocharger is deactivated, and the exhaust gas from the exhaust passage is concentrated to the turbine of the primary turbocharger. At the same time, in the high intake air amount range where the intake air amount is higher than the set value, the exhaust cut valve is opened and the secondary turbo supercharger is activated to remove exhaust gas from the exhaust passage. A so-called sequential turbo type engine is known in which exhaust gas is supplied to the turbines of two turbo superchargers to obtain an appropriate boost pressure while ensuring an intake air amount.

(Problem to be solved by the invention) In such a turbocharged engine, when transitioning from a low intake air amount region to a high intake air amount region such as during acceleration, ■When the exhaust cut valve opens, the primary turbo supercharging A sudden decrease in the flow rate of exhaust gas supplied to the machine.

■On the other hand, in the low intake air amount range, the secondary turbo supercharger is almost at a standstill, so it takes time for the secondary turbo supercharger to reach the rotation speed that allows supercharging.

For these reasons, the boost pressure sometimes drops and torque shock occurs.

By the way, in such a turbocharged engine, a leak passage that bypasses the exhaust cut valve is provided upstream of the supercharger in the exhaust passage dedicated to the secondary turbo supercharger, and an exhaust leak valve is provided in this leak passage, At least when transitioning from a low intake air amount region to a high intake air amount region, this exhaust leakage valve is opened across both of the above operating regions to relieve a portion of the exhaust gas upstream of the exhaust cut well to the secondary side turbine; The secondary turbine is pre-rotated by this relieved exhaust gas, and when the high intake air amount region is entered and the exhaust cut valve is opened, the secondary turbo supercharger is started to operate smoothly. If this exhaust leakage function is activated, the startup of the secondary turbo supercharger will be improved when transitioning from a low intake air volume range to a high intake air volume range such as during acceleration, thereby reducing temporary boost pressure during the transition. The drop is reduced and torque shock can be alleviated.

The present invention has been made in connection with this, and when transitioning from a low intake air amount region to a high intake air amount region, the exhaust gas flow that has passed through the open exhaust cut valve and the exhaust gas that has passed through the leakage passage. Focusing on the fact that the flow velocity of the exhaust gas flow toward the secondary turbine is reduced due to interference with the The purpose is to alleviate shock and improve boost pressure responsiveness.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, during a transition from a low intake air amount region to a high intake air amount region, for a predetermined period after the intake air amount exceeds a set value, The exhaust leak valve is forced closed so that the exhaust gas flow past the open exhaust cut valve is not disturbed by the exhaust gas flow from the leak passage.

Specifically, the solution taken by the present invention is to arrange a plurality of exhaust turbo superchargers in parallel on an intake road, and at least one of them is used as a secondary turbo supercharger. An exhaust cut valve is installed upstream of the turbocharger in the exhaust passage dedicated to the turbo supercharger, and the exhaust cut valve is opened to operate the secondary turbo supercharger only in the high intake air volume range where the intake air volume is higher than the set value. The assumption is that the engine is equipped with a turbocharger. In contrast, there is a leakage passage provided upstream of the supercharger in the exhaust passage dedicated to the secondary turbocharger, bypassing the exhaust cut valve, and a leakage passage provided in the leakage passage, which is provided at least from the low intake air amount region. An exhaust leak valve that opens across both operating ranges when transitioning to a high intake air volume range, and a valve that opens after the intake air volume exceeds a set value when transitioning from a low intake air volume range to a high intake air volume range. The exhaust leakage valve is configured to be provided with a valve closing means for forcibly closing the exhaust leakage valve during the period.

(Function) With the above configuration, in the present invention, the secondary turbocharger becomes inactive in the low intake air amount region, and exhaust gas is intensively supplied to the primary turbocharger, thereby ensuring high supercharging pressure. On the other hand, in a high intake air amount region, the secondary turbo supercharger operates and exhaust gas is supplied to the primary and secondary exhaust turbo superchargers, thereby achieving appropriate supercharging pressure while ensuring the intake flow rate.

At least when transitioning from the low intake air amount region to the high intake air amount region, the exhaust leakage valve opens across both operating regions, so the secondary turbine is pre-rotated by the exhaust gas passing through the leakage passage, and the high When entering the intake air amount range and opening the exhaust cut valve, the secondary turbocharger starts up better, reduces the temporary drop in boost pressure at the time of transition, alleviates torque shock, and increases boost pressure. improves responsiveness.

In that case, the valve closing means forcibly closes the exhaust leakage valve for a predetermined period after the intake air amount exceeds the set value when transitioning from the low intake air amount area to the high intake air amount area.
The exhaust gas flow passing through the open exhaust cut-off valve is not disturbed by the exhaust gas flow from the leakage passage. Therefore, the exhaust gas flow that has passed through the exhaust cut valve is directed smoothly to the secondary turbine at a high flow rate, further improving the start-up of the secondary turbocharger, alleviating temporary torque shock at the time of transition, and reducing supercharging. Improved pressure responsiveness is promoted.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a 20-
This figure shows a rotary piston engine with a turbo supercharger. In FIG. 1, 201 is an engine, and exhaust passages 202 . 203 are provided independently from each other. And these two exhaust passages 202, 2
03 has the turbine 205 of the primary turbocharger 204, and the other side has the secondary turbocharger 2.
06 turbines 207 are respectively arranged.

That is, in this engine 201, the exhaust passages 202 and 203 of each cylinder are independently connected to the turbine 205 of both the primary and secondary exhaust turbo superchargers 204 and 206.
, 207, both exhaust turbo superchargers 204
, 206, the exhaust dynamic pressure is effectively applied to both turbines 205 and 207 in the region where supercharging is performed, thereby improving supercharging efficiency. Two exhaust passages 202, 203
are joined downstream of both turbines 205 and 207 to form a single exhaust passage 224.

Further, the intake passage 209 is divided into two downstream of an air cleaner (not shown), and the blower 211 of the primary turbo supercharger 204 is in the middle of the first branch passage 210, and the blower 211 of the primary turbo supercharger 204 is in the middle of the second branch passage 212. The blower 213 of the secondary turbo supercharger 206 is installed. These branch passages 210° and 212 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 are connected to each blower 211°21.
It rejoins downstream of 3. Then, the intake passage 209, which has become one again, is provided with an r seat cooler 214,
A surge tank 215 is disposed downstream thereof, and a throttle valve 216 is disposed between the intercooler 214 and the surge tank 215. In addition, the intake passage 209
The downstream end thereof branches into two independent intake passages 217 and 218 corresponding to each cylinder of the engine 20, and is connected to each intake port (not shown). Each of these independent intake passages 217 and 218 has a fuel injection valve 219 therein.
, 220 are arranged.

On the upstream side of the intake passage 209, an air flow meter 221 is provided upstream of the branch of the first and second branch passages 210, 212 to detect the amount of intake air.

The two exhaust passages 202, 203 are communicated with each other by a relatively small diameter communication passage 222 upstream of both the primary and secondary turbochargers 204', 205. In the exhaust passage 203 in which the secondary turbine 207 is disposed, an exhaust cut valve 223 is provided immediately downstream of the opening position of the communication passage 222. In addition, the turbine 205°207 extends from the middle of the communication path 222.
A wastegate passage 225 is formed that communicates with the downstream combined exhaust passage 224, and a wastegate valve 227 to which a diaphragm type actuator 226 is linked is disposed in the wastegate passage 225. A leak passage 228 is formed that communicates the upstream portion of the waste gate valve 227 in the waste gate passage 225 with the downstream portion of the exhaust cut valve 223 in the exhaust passage 203 connected to the secondary turbine 207. That is, this leak passage 228 bypasses the exhaust cut valve 223 in the exhaust passage 203 upstream of the supercharger. The leakage passage 228 is provided with an exhaust leakage valve 230 linked to a diaphragm type actuator 229.

The exhaust cut valve 223 is linked to a diaphragm type actuator 231. On the other hand, the branch passage 2 in which the blower 213 of the secondary turbocharger 206 is disposed
12, an intake cut valve 232 is disposed downstream of the blower 213. This intake cut valve 232 is constituted by a butterfly valve, and is also linked to a diaphragm type actuator 233. Further, a relief passage 234 is formed in the branch passage 212 on the secondary side so as to bypass the blower 213, and a diaphragm type intake relief valve 235 is disposed in the relief passage 234.

The actuator 22 that operates the exhaust leak valve 230
9 is an electromagnetic solenoid type three-way valve 25 via a conduit 236.
It is connected to the output port of 3.

One input port of the three-way valve 253 is open to the atmosphere,
The other input port is connected via a conduit 254 to the branch passage 2 in which the blower 211 of the primary turbocharger 204 is installed.
No. 10 blower 211 is connected downstream. When the three-way valve 253 is ON and the pressure downstream of the blower 211 exceeds a predetermined value, the actuator 229 operates to open the exhaust leak valve 230, thereby closing the exhaust cut valve 223. During this period, a small amount of exhaust gas flows through the leakage passage 228 and is supplied to the secondary turbine 207. Therefore, the secondary turbo supercharger 206 starts rotating in advance before the exhaust cut valve 223 opens.

The actuator 23 that operates the intake cut valve 232
The pressure chamber No. 3 is connected to an output port of an electromagnetic solenoid type three-way valve 238 by a conduit 237. Furthermore, the actuator 23 that operates the exhaust cut valve 223 is
Another three-way valve 240 of the electromagnetic solenoid type is connected to the conduit 239.
connected to the output port of the Furthermore, the pressure chamber of the actuator 241 that operates the intake relief valve 235 is
Another three-way valve 243 of electromagnetic solenoid type is connected to the conduit 242.
connected to the output port of the Intake relief valve 235
As will be described later, the relief passage 23 is closed until a predetermined time before the exhaust cut valve 223 and the intake cut valve 232 open.
Leave 4 open. As a result, the leak passage 22
Secondary turbo supercharger 2 by exhaust gas flowing through 8
06 pre-rotates, the pressure upstream of the intake cut valve 232 rises to prevent it from entering the surging region, and also increases the rotation of the blower 213.

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

The above five electromagnetic solenoid type three-way valves 238, 240.2
43,245,253 and two fuel injection valves 219,
220 is controlled by a control unit 246 configured using a microcomputer. In addition to the output signal of the engine speed sensor and the output signal of the air flow meter 221, the control unit 246 receives the throttle opening, the boost pressure Pl downstream of the primary side blower 2]1, etc. control is carried out.

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 negative pressure tank 248 via a conduit 247.
49 is connected to an output port 270 of a differential pressure detection valve 250, which will be described later.

Intake negative pressure downstream of the throttle valve 216 is introduced into the negative pressure tank 248 via a check valve 251. Furthermore, 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
It is connected via a conduit 252 to the conduit 247 which is connected to the negative pressure tank 248 . 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. Further, one input port of the three-way valve 245 for controlling the wastegate valve 227 is open to the atmosphere, and the other manual boat is connected to the conduit 254.

As shown in FIG. 2, the differential pressure detection valve 250 has three chambers 264, 265, 2 inside its casing 261 formed by two first and second diaphragms 262, 263.
It is divided into 66 sections. A first input port 267 is opened in the first chamber 264 at one end, and a compression spring 268 is disposed between the inner surface of the end of the casing 25 61 and the first diaphragm 262. There is. Also, the second one in the middle
A second input port 269 is opened in the chamber 265, and an output port 270 is opened in the third chamber 266 on the other end side in the center of the end wall of the casing 261, and an atmosphere release port 1-271 is opened in the side wall. is opened. A valve body 272 is fixed to the first diaphragm 262 and extends through the second diaphragm 263 and toward the output port 270 of the third chamber 266.

The first input port 267 is connected by a conduit 273 to a first
As shown in the figure, it is connected to the downstream side of the intake cut valve 232, and introduces the supercharging pressure P1 downstream of the primary side blower 211 into the first chamber 264.

The second input port 269 is also connected upstream of the intake cut valve 232 by a conduit 274, so that the second input port 269 is connected upstream of the intake cut valve 232 when the intake cut valve 232 is closed.
The upstream pressure P2 is introduced. Pressures PI and P introduced from both input ports 267 and 269
2 (P26 PI) becomes a predetermined value or more, the valve body 272 opens the output port 270. This output capo-1-270 is connected to the conduit 249.
is connected to one of the input ports of a three-way valve 238 for controlling the intake cut valve 232. Therefore, when the three-way valve 238 is ON and the conduit 237 connected to the pressure chamber of the actuator 233 for operating the intake cut valve 232 is communicated with the conduit 249 connected to the output port of the differential pressure detection valve 250, the intake cut valve 232 When 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 PI-P2 disappears, and further, when the differential pressure P2-PI becomes larger than a predetermined value, the actuator Atmospheric air is introduced into 233, and the intake cut valve 23
2 will be opened. Also, the three-way valve 238 is turned OFF, and the conduit 237 on the actuator 233 side is connected to the negative pressure tank 2.
48, negative pressure is supplied to the actuator 233 and the intake cut valve 232 is closed.

On the other hand, when the three-way valve 240 for controlling the exhaust cut valve 27 and 23 is OFF, the exhaust cut valve 223
3 operation actuator 23] connects the conduit 239 connected to the pressure chamber to the conduit 252 on the negative pressure tank 248 side, the actuator 231 is closed by being supplied with negative pressure.

Further, when the three-way valve 240 is turned on and the conduit 239 on the output side is released to the atmosphere, the exhaust cut valve 223 is opened and supercharging by the secondary turbo supercharger 206 is performed.

The intake relief valve 235 is operated by the actuator 241 when the three-way valve 243 for controlling the intake relief valve 235 is OFF and the conduit 242 connected to the pressure chamber of the actuator 241 for operating the intake relief valve 235 is communicated with the negative pressure tank 248 side. Opens when negative pressure is supplied, and
When the three-way valve 243 is turned on and the conduit 242 connected to the pressure chamber of the actuator 241 is released to the atmosphere, it is closed.

In addition, the actuator 2 for operating the waste gate valve 227
26 communicates downstream of the primary side blower 211 via a conduit 254 when the three-way valve 245 of the wastegate valve 227 control 8 is ON, and when the pressure downstream of this blower exceeds a predetermined value, the actuator 226 is activated. The wastegate valve 227 is then opened to relieve exhaust gas and optimize the supercharging pressure characteristics. Also,
When this three-way valve 245 is OFF, it is released to the atmosphere and the wastegate valve 227 is closed.

In this embodiment, hysteresis is provided in the opening and closing operations of the exhaust cut valve 223, the intake cut valve 232, and the intake relief valve 235, as will be described later. In addition, in order to prevent intake air from flowing backward into the secondary blower when the exhaust cut valve 223 closes and the intake cut valve 232 remains open during the transition from the high intake air amount region to the low intake air m region, this region is The intake cut valve 232 is forcibly closed after a predetermined time (for example, 2 seconds) has elapsed starting from the time when the exhaust cut valve 223 is closed.

FIG. 3 is a control map showing the opening/closing control of the intake cut valve 232, the exhaust cut valve 9223, the intake relief valve 235, and the waste gate valve 227, together with the basic control of the exhaust leak valve 230. This map is stored in the control unit 246, and based on this map, the five electromagnetic solenoid type three-way valves 238, 240, 2
43,245°253 control is performed.

When transitioning from a low intake air amount region to a high intake air amount region, the intake relief valve 235 is open in a region where the engine speed R is low or the intake air amount Q is small.
Pre-rotation of the secondary turbocharger 206 is performed by opening the exhaust leakage valve 230. Then, when the engine speed reaches R2 or the intake air amount reaches the 02-R2 line, the solenoid type three-way valve 243 for controlling the intake relief valve 235 is turned ON, the intake relief valve 235 is closed, and then the exhaust gas is cut off. Until the valve 223 opens, the pressure downstream of the secondary blower 213 increases. When the line Q4-R4 is reached, the exhaust cut valve 2
23 control solenoid type three-way valve 240 is turned ON and the exhaust cut valve 223 is opened, then the Q6-R6 line is reached, the solenoid type three-way valve 238 for controlling the intake cut valve 232 is turned ON, and the intake When the cut valve 232 opens, supercharging by the secondary turbo supercharger 206 starts. In other words, this Q6
-The R6 line enters the supercharging area with both the primary and secondary superchargers. Note that the actuator 233 that drives the intake cut valve 232 is not controlled only by the operation of the solenoid 238, but is supplied with atmospheric pressure, which is the pressure source that opens the intake cut valve 232, via the differential pressure detection valve 250. Therefore, the actual opening operation of the intake cut valve 232 is delayed with respect to the operation of the solenoid 238.

Therefore, the solenoid 23 for controlling the intake cut valve 232
8 from OFF to ON Q6 above. The R6 line is set in consideration of the delay caused by the differential pressure detection valve 250, and as a result, the Q6. The R6 line is υ1 air cut valve 223 control solenoid 240 or Q4 which changes from OFF to ON. R4
is considered to be close to the line.

1 Also, these Q6. R6 and Q4. R4 can also be matched.

Conversely, when transitioning from a high intake air amount region to a low intake air amount region, each solenoid type three-way valve 238, 240, 243 that controls the intake cut valve 232, the exhaust cut valve 223, and the intake relief valve 235 has hysteresis. Third
Q5-R5 and Q3-R3, respectively, as shown by broken lines in the figure.
, Ql-R1. That is, when transitioning from a high intake air amount area to a low intake air amount area, Q3. When the R3 line is reached, the exhaust cut valve 2
23 close control is performed, and then the state shifts to the low intake air amount region and Q5. When the R5 line is reached, the intake cut valve 232
The intake relief valve 23 is closed after a delay.
5 opening control is performed.

By closing the intake cut valve 232 later than the exhaust cut valve 223 in this way, the occurrence of surging during transition to the low intake air amount region is prevented.

In addition, in this embodiment, the line for turning off the solenoid type three-way valve 245 for controlling the waste gate valves 22 and 27 is connected to the solenoid 240 for controlling the exhaust cut valve 223.
The lines Q4R4 and Q3-R3, which are the ON and OFF lines, are made to coincide with each other.

When transitioning from the low intake air amount region to the high intake air amount region, the exhaust leakage valve 230 is forcibly closed for a predetermined period T after the exhaust cut valve 223 is opened.

Incidentally, in FIG. 10, the bent portions of each of the above lines are on the so-called no-load line or low-load line.

Therefore, in the above embodiment, when the engine is in the low intake air amount region where the intake air amount is smaller than line Q6-R6, the introduction of exhaust gas to the secondary turbocharger 206 is stopped, so that the primary turbocharger machine 204
Only the boost pressure is activated and high boost pressure can be obtained easily. On the other hand, when the engine is in a high intake air amount region where the intake air amount is larger than the above line Q6-R6, both the primary turbo supercharger 204 and the secondary turbo supercharger 2036 operate to ensure the intake flow rate. Appropriate boost pressure can be obtained.

Then, when transitioning from the low intake air amount region to the high intake air amount region, the exhaust leakage valve 230 opens across both the low intake air amount region and the high intake air amount region, so that the leakage passage 22
The exhaust gas passing through the secondary turbine 2
Secondary turbo supercharger 206 when 07 is pre-rotated and enters the high intake air amount region and exhaust cut valve 223 is opened.
The rise of the boost pressure is improved, the temporary drop in boost pressure at the time of transition is reduced, the torque shock is alleviated, and the responsiveness of the boost pressure is improved.

In that case, when transitioning from the low intake air amount region to the high intake air amount region, the exhaust leakage valve 230 is forcibly closed for a predetermined period T after the exhaust cut valve 223 is opened. The exhaust gas flow passing through is not disturbed by the exhaust gas flow from the leakage passage 228.

Therefore, the exhaust gas flow that has passed through the exhaust cut valve 223 is smoothly transferred to the secondary turbine 207 at a high flow rate.
4, the start-up of the secondary turbocharger 206 is further improved, the temporary torque shock at the time of transition is alleviated, and the responsiveness of the supercharging pressure is improved.

Figure 4 shows the relationship between the solenoid operating states of the six valves and the transition of operating states (the left side of the horizontal axis is the low intake air m range, and the right side is the high intake air amount range) based on the characteristic diagram in Figure 3 above. This is what I saw. As can be seen from this figure, the hysteresis of the opening/closing operation of the exhaust cut valve 223 is completely included in the hysteresis of the opening/closing operation of the intake cut valve 232. Note that the solenoid 238 for controlling the intake cut valve 232 is connected to the Q6. Even if R6 is turned ON, the actual opening operation of the intake cut valve 232 is delayed due to the action of the differential pressure detection valve 250, as shown by the broken line in the figure. Therefore, this Q6. R6 is the exhaust cut valve 223 open 17! as described above. The line is close to or the same line as Q4R4 of I control.

On the other hand, the closing operation of the intake cut valve 232 does not involve a delay of two feet with respect to the operation of the solenoid 238, so the setting line Q5. R5 is 5 Q5<Q3. It is necessary to satisfy R5<R3.

Next, control of the six valves based on the characteristics shown in FIG. 3 will be explained using the control circuit shown in FIG. 5. The intake relief valve operating solenoid 243 is connected to the first comparison circuit 11 shown at the top of the figure.
1 and the output of the second comparison circuit 112 shown below it are controlled by the output of the first OR circuit 121 which is manually operated. Here, the first comparison circuit 111 compares the intake air iQ, which is the detection signal of the air flow meter 221, with the output value of the first addition circuit 131, which is a reference value. The first adder circuit 131 receives the set value Q1 corresponding to the Q1 line in FIG. It is configured to be inputted via the first gate 141, and when the first gate 41 is opened, the first
It is output to the comparator circuit 111 of the first game 1-1-
When 41 is closed, Ql is output to the first comparison circuit 111 as a reference value. And this first gate 1
416 is opened and closed by the output of the first OR circuit 121.

The second comparison circuit 112 compares the engine rotation speed R detected by the engine rotation speed sensor with the output value of the second addition circuit 132, which is a reference value. The second adder circuit 132 receives the setting value R1 corresponding to the R1 line in FIG. is configured to be input through the second
When the gate 142 of is opened, R1+R' 1-R2
is output to the second comparison circuit 112 as a reference value, and
When the second gate 142 is closed, it outputs R1 as a reference value to the second comparison circuit 112. 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 engine rotation speed R with respective reference values that are outputs of the first and second addition circuits, and compare Q or R. is equal to or higher than the reference value 7, an ON signal is output to the intake relief valve operating solenoid 243 (when ON, the intake relief valve 23
5 is closed). First and second gates 141, 142
is closed when the output signal of the first OR circuit 121 is ON, and is opened when the OR circuit signal is OFF. Therefore, at the time of transition from the low intake air amount region to the high intake air amount region, the output signal of the first OR circuit 121 is OFF, so each gate 141, 142 is opened and the first and second comparison circuits 111 ．． ．． Q2+R as a reference value to 112
2 is input. Therefore, in FIG. 3, Q2. When the R2 line is reached, an ON signal is issued and the intake relief valve 23
5 will be held. Further, the first and second gates 141 and 142 are closed by this ON signal, and thereby,
The reference values of Q and R are Ql and R1, respectively. In other words, the line is set with hysteresis corresponding to Q'1 and R'l in preparation for a shift in the opposite direction.

The exhaust cut valve actuation solenoid 240 is also controlled by a similar control circuit. In other words, the third comparison circuit 113 for the suction 8 large air fiQ also
A fourth comparison circuit 114 is also provided for the engine speed R, and the outputs of these comparison circuits 113 and 114 are sent to the solenoid 240 via the second OR circuit 122.

For the third comparator circuit 113, a third adder circuit 133
However, a fourth addition circuit 134 is similarly provided for the fourth comparison circuit 114. Then, the set value Q3 is input to the third adder circuit 133, and Q10 (however, Q3 +Q'3-
Q4) is input. Similarly, the fourth addition circuit 134
is the set value R3 and R' via the fourth gate 144.
3 (however, R3+R' 3 =R4) is input.

Similarly, the fourth adder circuit 134 receives the set value R3 and R′3 (R3+R
' 3 =R4) is input. This circuit operates in the same manner as in the first and second comparator circuits above, thereby:
04 in Figure 3 when transitioning to the high intake air amount area. The exhaust cut valve 223 is opened based on the Ra line, and when transitioning to the 9 low intake air amount region, the Q3. The valve 223 is operated to close by the R3 line.

For the intake cut valve operating solenoid 238, the fifth
A similar control circuit is also provided which supplies the outputs of the sixth comparison circuits 115, 1.16 via the third OR circuit 123. This control circuit includes each comparison circuit 11
5,116, the fifth and sixth adder circuits 135,1
36, and also includes fifth and sixth gates 145, 146 for each adder circuit 135, 136.

The basic operation is the same as the circuit for the six valves described above. In other words, when transitioning to the high intake air amount region, the Q6R6
Intake cut valve opening control is performed using the lines Qs and Rs, and intake cut valve closing control is performed using the Qs and Rs lines when transitioning to the low intake air amount region. Here, Q6 and R6 are similarly Q5+Q' s =Q6. R5+R'5=RG
It is set in the form of

However, in the case of this intake cut valve control circuit, a seventh gate 1-147 is connected to the output side of the third OR circuit 123.
is connected, and a control signal is sent to the solenoid 238 via this gate 147.

and the second OR circuit 12 for operating the exhaust cut valve.
A timer 150 is provided which starts counting up starting from when the output of 2 changes from ON to OFF.
A seventh comparison circuit 117 is provided that issues an ON signal when the count value of the timer 150 exceeds a set value (for example, a value corresponding to 2 seconds), and the ON signal is output from the seventh comparison circuit 117. At this time, 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 to 06. R6 and also resets the timer 150. - Dan No. 7
When the gate 147 of the seventh comparison circuit 117 closes, the seventh comparison circuit 117
The output of will be OFF, but the reference value which is the switching line as mentioned above will be 06. Since the valve is changed to R6, the intake cut valve actuating solenoid 238 is maintained in the closed operating state. This prevents surging from occurring due to the exhaust cut valve solenoid 238 being in the OFF state and the intake cut valve solenoid 240 being in the ON state 1 for a long time during the transition to the low intake air amount region.

Furthermore, the exhaust leak valve solenoid 253 is also controlled based on the control signal output to the exhaust cut valve operating solenoid 240. That is, 118 is an eighth comparison circuit, and the comparison circuit 118 includes the above-mentioned OR circuit 1.
22 output signals are input. This comparison circuit 118
Then, it is determined whether the output signal of the OR circuit 122 "changed from ON to OFF" or "changed from OFF to ON."

When the output signal of the OR circuit 122 changes from OFF to ON, that is, when the exhaust cut valve 223 switches from closing operation to opening operation, the exhaust leakage valve solenoid 2
53 is stopped for a predetermined time T, and the exhaust leak valve 223 is closed. Specifically, a timer 151 is connected to the comparison circuit 118, and the timer 1
51 is connected to a ninth comparison circuit 119, and the output signal of this comparison circuit 119 is sent to the exhaust leakage valve solenoid 253.
has been entered. Therefore, when the output signal of the OR circuit 1222 changes from OFF to ON, the timer 151
starts counting up, and this count value becomes the set value T.
When the value exceeds 0, an ON signal is output from the comparison circuit 119, and the operation of the exhaust leak valve 230 is permitted. Note that the timer 15 is reset when the output signal of the OR circuit 122 changes from ON to OFF.

In the above configuration, the comparison circuits 118, 119 and the timer 151 operate the exhaust leakage valve for a predetermined period after the intake air amount exceeds the set value when transitioning from the low intake air amount area to the high intake air amount area. It constitutes a valve closing means 301 that forcibly closes the valve 223.

(Effects of the Invention) As explained above, according to the control device for a turbocharged engine of the present invention, a plurality of exhaust turbochargers are arranged in parallel in the intake passage, and at least one of them is arranged in parallel. The exhaust turbo supercharger is used as a secondary turbo supercharger, and an exhaust cut valve is provided upstream of the supercharger in the exhaust passage dedicated to the secondary turbo supercharger, and 3. The exhaust cut valve is opened only to operate the secondary turbo supercharger, and a leak passage is provided upstream of the supercharger in an exhaust passage exclusively for the secondary turbo supercharger, bypassing the exhaust cut valve, and the leak passage. and an exhaust leakage valve that opens across both operating ranges at least when transitioning from the low intake air volume range to the high intake air volume range, and the In some cases, the exhaust leakage valve is forcibly closed for a predetermined period after the intake air amount exceeds the set value, ensuring high boost pressure in the low intake air amount region and reducing pressure in the high intake air amount region. While achieving the basic effect of obtaining appropriate boost pressure while ensuring intake flow rate, the exhaust leakage function reduces temporary boost pressure during the transition from low intake air amount area to high intake air amount area. In addition, during this transition, the exhaust gas flow that has passed through the open exhaust cut valve is smoothly transferred to the secondary side 4 turbine at a high flow rate. In addition, it is possible to alleviate temporary torque shock at the time of transition and to improve responsiveness of supercharging pressure.

[Brief explanation of drawings]

The drawings illustrate an embodiment of the present invention, in which Fig. 1 is a general schematic diagram, Fig. 2 is a sectional view of the differential pressure detection valve, Fig. 3 is a map showing the operating area of the joint venture, and Fig. 4 is a diagram of the joint venture. FIG. 5 is a control circuit diagram. 202...Exhaust passage 203...Exhaust passage 204...Primary turbo supercharger 206...Secondary turbo supercharger 207...Turbine 223...Exhaust cut valve 228...Leak passage 230... ...Exhaust leak valve 301...Valve closing means 5

Claims (1)

[Claims] (1) A plurality of exhaust turbo superchargers are arranged in parallel in the intake passage, and at least one of the exhaust turbo superchargers is used as a secondary turbo supercharger to supercharge the turbo supercharger in the exhaust passage dedicated to the secondary turbo supercharger. Install an exhaust cut valve upstream of the feeder,
In a turbocharged engine that opens the exhaust cut valve to operate the secondary turbocharger only in a high intake air volume range where the intake air volume is higher than the set value, an exhaust passage dedicated to the secondary turbocharger is installed. a leakage passage provided in the upstream of the turbocharger bypassing the exhaust cut valve; An exhaust leak valve that opens across the range, and a valve closing means that forcibly closes the exhaust leak valve for a predetermined period after the intake air amount exceeds a set value when transitioning from a low intake air amount area to a high intake air amount area. A control device for a turbocharged engine, characterized by comprising: