JPH0388918A - Control device for engine with turbo-supercharger - Google Patents

Abstract

PURPOSE:To maintain at high level the exhaust gas pressure to be applied to a turbine of a primary turbo supercharger by stopping for a certain period the operation of a relief means when a secondary turbo supercharger is changed over from operation into out of operation. CONSTITUTION:A solenoid type three-way valve 245 and a solenoid 253 are turned from off to on by a control unit 246 after elapse of a certain period on the occasion of transition from the high suction air amount range to the low suction air amount range. Thereby a waste gate valve 227 and an exhaust gas leak valve 230 are shut forcedly during this period, and no exhaust gas relief will take place. In case therefore the suction air amount is once increased and then decreased for ex. at the time of reacceleration or shifting-up under acceleration, to be followed by increasing again, the exhaust gas pressure applied to a turbine 205 of a primary turbo supercharger 204 is maintained high, and the turbo lag of the turbo supercharger 204 is suppressed when the suction air amount is increased again, which provides operation with good rising characteristic to ensure enhancement of the running characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a control device for a turbocharged engine, and more particularly to a control device for a turbocharged engine, which is equipped with primary and secondary exhaust turbochargers, and which controls the control of the secondary turbocharger according to the flow rate of exhaust gas. Relates to something that activates or deactivates a supercharger.

(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, and the blowers of these two exhaust turbo superchargers are connected to the intake passage of the engine, and an exhaust cut valve is installed in the exhaust passage upstream of the turbine of the secondary turbo supercharger. When the amount 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 intensively supplied to the turbine of the primary turbocharger to create a high boost pressure. On the other hand, when the amount of intake air is larger than the set value, the exhaust cut valve is opened and the secondary turbo supercharger is activated, and the exhaust gas from the exhaust passage is supplied to the turbines of the two exhaust turbo superchargers and sucked. There is a known system that obtains an appropriate boost pressure while securing the amount of intake air.

(Problems to be Solved by the Invention) By the way, in such a control device for a turbocharged engine, a wastegate passage that bypasses the turbine of the primary turbocharger is provided in the exhaust passage, and a A wastegate valve is provided, and when the intake pressure downstream of the blower of the primary turbocharger reaches a predetermined value or higher, the wastegate valve is opened and a part of the exhaust gas supplied to the turbine of the primary turbocharger is transferred to the turbine. Relief is carried out to the downstream exhaust passage to optimize the boost pressure characteristics.

In this way, in a turbocharged engine equipped with a wastegate valve, the amount of intake air increases once, then decreases, and then increases again, for example when shifting up during acceleration or accelerating again. In this case, the secondary turbo supercharger is activated when the intake air amount increases first, then the secondary turbo supercharger is deactivated when the intake air amount decreases, and then the intake air amount increases again. When the secondary turbocharger is activated again. In that case,
When the amount of intake air decreases, the intake pressure downstream of the floor of the primary turbocharger increases and exceeds the predetermined value, so that the wastegate valve opens and exhaust relief is performed through the wastegate passage. As a result, when the intake air amount increases again thereafter, the rise of the exhaust pressure applied to the turbine of the primary turbocharger becomes difficult, resulting in so-called turbo lag, resulting in poor running performance.

In addition, a leak passage is provided that bypasses the exhaust cut valve, and an exhaust leak valve is provided in the leak passage, so that when the exhaust cut valve is closed, the intake pressure downstream of the blower of the primary turbocharger exceeds a predetermined value. When this occurs, the exhaust leak valve is opened to leak a portion of the exhaust gas supplied to the turbine of the primary turbocharger to the turbine of the secondary turbocharger, thereby relieving this exhaust gas. Pre-rotation is performed. In this way, even in a turbocharged engine equipped with an exhaust leak valve, if the intake air amount increases once, then decreases, and then increases again, as in the case with the above-mentioned waste gate valve, When the intake air amount decreases, the intake pressure downstream of the blower of the primary turbocharger increases and exceeds the predetermined value, so that the exhaust leak valve opens and exhaust relief is performed through the leak passage. the result,
After that, when the amount of intake air increases again, the rise of the exhaust pressure applied to the turbine of the primary turbocharger becomes difficult, resulting in turbo lag and poor running performance.

The present invention has been made with attention to these points,
Its purpose is to relieve the exhaust gas supplied to the turbine of the primary turbocharger according to the intake pressure downstream of the primary turbocharger's blower, like the waste gate valve and exhaust leak valve mentioned above. In a turbocharged engine equipped with a relief means that has the function of It's about getting rid of it.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, first, when the secondary turbocharger is switched from operation to inoperation,
The exhaust leaf provided by the relief means is stopped for a predetermined period of time to maintain a high exhaust pressure applied to the turbine of the primary turbocharger.

Specifically, the solution taken by the present invention includes primary and secondary exhaust turbo superchargers each having a turbine in an exhaust passage provided in parallel with the engine, and is equipped with a primary and a secondary exhaust turbo supercharger each having a turbine in an exhaust passage provided in parallel with the engine. The assumption is that the engine is equipped with a turbo supercharger in which only the secondary turbo supercharger is operated. In response to this, a relief means for relieving the exhaust gas supplied to the turbine of the primary turbocharger and a secondary turbocharger are activated in accordance with the intake pressure downstream of the blower of the primary turbocharger. A relief stop means is provided for stopping the operation of the relief means for a predetermined period when the relief means is switched to non-operation.

Furthermore, a specific timing for stopping the operation of the relief means is when the exhaust cut valve is switched between operating and inactivating the secondary turbocharger.

The specific solution in this case is based on the above configuration, and the exhaust passage dedicated to the secondary turbocharger is supplied with exhaust gas to the turbine of the secondary turbocharger when it is opened, and the secondary turbocharger is activated. On the other hand, an exhaust cut valve is provided, which shuts off the supply of exhaust gas to the turbine of the secondary turbo supercharger and makes the secondary turbo supercharger inactive when it is closed, and the exhaust cut valve opens the relief stop means. The configuration is such that the operation of the relief means is stopped for a predetermined period when the operation is switched from the closed operation to the closed operation.

(Function) With the above configuration, in the present invention, when the amount of intake air is small, the secondary turbo supercharger is deactivated and exhaust gas is intensively supplied to the primary turbo supercharger, thereby ensuring high supercharging pressure. On the other hand, when the amount of intake air is large, the secondary turbo supercharger operates and exhaust gas is supplied to both exhaust turbo superchargers, so that appropriate supercharging pressure can be obtained while ensuring the intake air flow rate.

Furthermore, the exhaust gas supplied to the turbine of the primary turbocharger is relieved by the relief means in accordance with the intake pressure downstream of the blower of the primary turbocharger.
Boost pressure is optimized.

When the secondary turbo supercharger is switched from operating to non-operating, the operation of the relief means is stopped for a predetermined period by the relief stop means, and exhaust relief by the waste gate valve or exhaust leak valve is not performed. When the amount of intake air increases, then decreases, and then increases again, such as when shifting up during acceleration or reaccelerating, the exhaust pressure applied to the primary turbocharger turbine is maintained high. Therefore, when the intake air amount increases again, the turbo lag of the primary turbo supercharger is suppressed, and the primary turbo supercharger starts up smoothly and operates, improving driving performance.

In particular, the timing of stopping the operation of the relief means is
When the exhaust cut valve that switches between activation and deactivation of the secondary turbocharger is activated, the relief of exhaust gas to the primary turbocharger is stopped for a predetermined period at the same time as the exhaust gas flows into the primary turbocharger. The exhaust pressure applied to the turbine of the primary turbocharger is reliably maintained at a high level, and the start-up of the operation of the primary turbocharger is improved, resulting in improved running performance.

(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 and 203 for each cylinder are provided independently from each other. And these two exhaust passages 202.20
3, the turbine 205 of the primary turbocharger 204 is placed on one side, and the secondary turbocharger 20 is placed on the other side.
6 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, 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, an intercooler 214 is disposed in the intake passage 209, which has become one again, and a surge tank 215 is disposed downstream of the intercooler 214, and a throttle valve 216 is disposed between the intercooler 214 and the surge tank 215. It is set up. Further, 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 boat (not shown). Each of these independent intake passages 217 and 218 has a fuel injection valve 219.
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. Further, a wastegate passage 225 is formed which extends from the middle of the communication passage 222 and communicates with the combined exhaust passage 224 downstream of the turbine 205 207.
5 is provided with a wastegate valve 227 to which a diaphragm type actuator 226 is linked. A leakage passage 228 is formed that communicates the upstream part of the wastegate valve 227 in the wastegate passage 225 with the downstream part of the exhaust cut valve 223 in the exhaust passage 203 connected to the secondary turbine 207. An exhaust leak valve 230 is provided which is linked to the actuator 229 of the exhaust gas leak valve 230 .

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 composed of a butterfly valve, and is also driven by a diaphragm type actuator 2.
33. Further, a relief passage 234 is formed in the branch passage 212 on the secondary side so as to bypass the blower 213.
4 is provided with a diaphragm type intake relief valve 235.

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

One input port of the three-way valve 253 is open to the atmosphere;
The other input boat is connected via a conduit 254 to the branch passage 2 in which the blower 211 of the primary turbocharger 204 is installed.
10 downstream of the proa 211. 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 leak 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. Further, the actuator 231 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 and enters the surging region, and the rotation of the proar 213 is increased.

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 proar 211, etc., and based on these, performs control as described below. will be held.

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 to the output port 27 of the differential pressure detection valve 250, which will be described later.
Connected to 0.

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 gas cut valve is open to the atmosphere, and the other human-powered boat 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 human-powered boat is open to the atmosphere. In addition, waste gate valve 227
One input port of the three-way control valve 245 is open to the atmosphere, and the other input port is connected to the conduit 254.

As shown in FIG. 2, the differential pressure detection valve 250 has three chambers 264, 265,
It is divided into 266 sections. A first input port 267 is opened in the first chamber 264 at one end, and the inner surface of the end of the casing 261 and the first diaphragm 2
A compression spring 268 is disposed between the spring 62 and the spring 62 .

In addition, a second input port 26 is provided in the middle second chamber 265.
In the third chamber 266 on the other end side, an output port 270 is opened in the center of the end wall of the casing 261, and an atmosphere release boat 271 is opened in the side wall. and,
The first diaphragm 262 has a second diaphragm 2
63 and extends toward the output port 270 of the third chamber 266. A valve body 272 is fixedly provided.

The first human-powered boat 267 is connected to the second human-powered boat by a conduit 273.
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 prower 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, P introduced from this re-input boat 267.269
2 (P2-Pi) exceeds a predetermined value, the valve body 27
2 opens output port 270. This output port 270 is connected via a conduit 249 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 turned on, the conduit 2 connected to the pressure chamber of the actuator 233 for operating the intake cut valve 232
37 is in communication 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 secondary side supercharging pressure P2 approaches the primary side supercharging pressure P1, the differential pressure Pi-P2 disappears, and the differential pressure P2-PL becomes larger than a predetermined value, the actuator 233 Atmospheric air is introduced into the air, and the intake cut valve 232 is opened. Also, the three-way valve 238 is OF
When the conduit 237 on the actuator 233 side is connected to the conduit 247 connected to the negative pressure tank 248 at F, negative pressure is supplied to the actuator 233,
Intake cut valve 232 is closed.

On the other hand, the exhaust cut valve 223 is activated when the three-way valve 240 for controlling the exhaust cut valve 223 is OFF and the actuator 231 for operating the exhaust cut valve 223 connects the conduit 239 connected to the pressure chamber to the conduit 252 on the negative pressure tank 248 side. , is closed by supplying negative pressure to the actuator 231.

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 is a three-way valve 245 for controlling the waste gate valve 227
is ON, the primary side proa 2 is connected via the conduit 254.
When the pressure downstream of this proa reaches a predetermined value or higher, an actuator 226 operates to open a wastegate valve 227 to relieve exhaust gas and optimize the supercharging pressure characteristics. . Also, this three-way valve 24
When valve 5 is OFF, it is released to the atmosphere and the waste gate valve 2
27 closes.

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 side proa when the exhaust cut valve 223 closes and the intake cut valve 232 remains open during the transition from the high intake air amount area to the low intake air amount area, this area 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 shows an intake cut valve 232, an exhaust cut valve 223,
This is a control map showing the opening/closing control of the intake relief valve 235 and the waste gate valve 227 together with the opening/closing 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, 243, 2
45°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 and the exhaust leakage valve 230 is opened in a region where the engine speed R is low or the intake air ff1Q is small. Pre-rotation of the secondary turbocharger 206 is performed by this. Then, when the engine speed reaches R2 or the intake air amount reaches the line 02-R2, the solenoid type three-way valve 243 for controlling the intake relief valve 235 is turned on, and the intake relief valve 23
5 is closed until the exhaust cut valve 223 is opened, the pressure downstream of the secondary proar 213 increases. When the Q4-R4 line is reached, the solenoid type three-way valve 240 for controlling the exhaust cut valve 223 is turned ON and the exhaust cut valve 223 is opened, and then the Q6-R6 line is reached, and the solenoid type three-way valve 240 for controlling the exhaust cut valve 223 is turned on. When the solenoid type three-way valve 238 is turned on and the intake cut valve 232 is opened, supercharging by the secondary turbo supercharger 206 starts. In other words, the engine enters the supercharging region using both the primary and secondary superchargers at the Q6-R6 line. still,
Actuator 233 that drives the intake cut valve 232
is not only controlled by the operation of the solenoid 238, but also depends on the actual opening of the intake cut valve 232 because atmospheric pressure, which is the pressure source that opens the intake cut valve 232, is supplied via the differential pressure detection valve 250. Actuation will be delayed relative to the actuation of solenoid 238. Therefore, Q6 above turns the intake cut valve 232 control solenoid 238 from OFF to ON. The R6 line is set in consideration of the delay caused by the differential pressure detection valve 250, and as a result, the Q6. For the R6 line, the exhaust cut valve 223 control solenoid 240 is OFF.
Q4. It is assumed that the line is close to the line R4.

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.

In this way, by closing the intake cut valve 232 later than the exhaust cut valve 223, surging is prevented from occurring when transitioning to the low intake air amount region.

Also, in this embodiment, the solenoid type three-way valve 245 for controlling the waste gate valve 227 is turned on.

The lines to be turned off are Q4-R4 and Q3, which are the ON and OFF lines for the exhaust cut valve 223 control solenoid 240.
- Match each line of R3.

That is, when transitioning from a low intake air amount region to a high intake air amount region, the solenoid 245 is turned from ON to OFF on the line Q4-R4. In addition, when transitioning from a high intake air amount area to a low intake air amount area, the solenoid 245 is turned on from OFF after a predetermined time has passed after crossing the Q3-R3 line. The line that turns on and off the three-way valve 253 is also the exhaust cut valve 22.
3 control solenoid 240 is turned on.

It is matched with each line of Q4-R4 and Q3-R3 which are OFF lines. That is, when transitioning from the low intake air amount area to the high intake air amount area, the solenoid 253 is turned from ON to OFF on the line Q4-R4. In addition, when transitioning from the high intake air amount area to the low intake air amount area, the solenoid 253
Turn from OFF to ON.

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

Therefore, in the above embodiment, when the engine is in a lower intake air amount region than line Q6-R6, the introduction of exhaust gas to the secondary turbocharger 206 is stopped, so only the primary turbocharger 204 is activated. As a result, high boost pressure can be obtained quickly. On the other hand, when the engine is in a higher intake air amount region than the above line Q6-R6, both the primary turbo supercharger 204 and the secondary turbo supercharger 206 operate to ensure the intake flow rate and maintain appropriate supercharging pressure. You will get it.

Also, when transitioning from the high intake air amount area to the low intake air amount area, the solenoids 245 and 253 are turned on from OFF after a predetermined time has passed after crossing the line Q3-R3, so during this predetermined time, the The gate valve 227 and the exhaust leak valve 230 are forcibly closed, and the waste gate valve 227 and the exhaust leak valve 230 do not provide exhaust relief. Therefore, as shown in Figure 6, when the intake air amount increases once, then decreases, and then increases again, such as when shifting up during acceleration or reaccelerating, primary turbo overflow occurs. When the exhaust pressure applied to the turbine 205 of the charger 204 is maintained high and the intake air amount increases again, the turbo lag of the primary turbocharger 204 is suppressed, and the primary turbocharger 204
starts up and operates smoothly, improving running performance. That is,
In FIG. 6, the broken line shows the conventional example, and the solid line shows the example of the present invention. Regarding the engine intake air amount, the turbo lag has been improved by the amount shown by the diagonal line.

In addition, regarding the amount of exhaust gas, the amount of gas leaking from the waste gate valve 227 is reduced by the amount shown by diagonal lines.

In particular, the wastegate valve 227 and the exhaust leakage valve 23
0 is closed for a predetermined period of time after the exhaust cut valve 223 is closed, so the relief of exhaust gas to the primary turbo supercharger 204 is stopped for a predetermined period of time when the exhaust gas flows into the primary turbo supercharger 204. The exhaust pressure applied to the turbine 205 of the primary turbocharger 204 is reliably maintained at a high level, and the start-up of the operation of the primary turbocharger 24 is improved, resulting in improved running performance.

Figure 4 shows the response solenoid operating state in relation to the transition of operating conditions (the left side of the horizontal axis is the low intake air amount region, and the right side is the high intake air amount region) based on the characteristic diagram in Figure 3 above. That's 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 set to 06. 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. As mentioned above, R6 is a line close to or the same line as 04°R4 for controlling the opening of the exhaust cut valve 223.

On the other hand, the closing operation of the intake cut valve 232 does not involve the above-mentioned delay with respect to the operation of the solenoid 238.
The setting line is Q5. R5 is Q5<Q3. R5<
It is necessary to set it to R3.

Next, response control 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.
It is controlled by the output of the first OR circuit 121 which receives as input the output of 1 and the output of the second comparison circuit 112 shown below. Here, the first comparison circuit 111 compares the intake air ff1Q, 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. Then, the first addition circuit 131
The setting value Q1 corresponding to the Q1 line in the figure is input, and the value Q/, for this Ql (however, the configuration is such that the value Q+10't-Q is inputted via the first gate 141). When the first gate 141 is opened, Q+ +Q'1-Q2 is output as a reference value to the first comparison circuit 111, and when the first gate 141 is closed, Ql is output as a reference value. as the first comparison circuit 11
Output to 1. The first gate 141 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, R, 10R', -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 the outputs of the first and second addition circuits, and compare Q or R. outputs an ON signal to the intake relief valve operating solenoid 243 when the
When turned on, the intake relief valve 235 closes). The first and second gates 141 and 142 are closed when the output signal of the first OR circuit 121 is ON, and are opened when the OR circuit signal is OFF. Therefore, when transitioning from the low intake air amount area to the high intake air amount area, the first OR circuit 12
Since the output signal of gate 1 is OFF, each gate 141, 1
42 is opened and the first and second comparison circuits 111, 112
Q2. R2 is input. therefore,
When the line Q21R2 is reached in FIG. 3, an ON signal is issued and the intake relief valve 235 is opened. Also, this ON
The signal closes the first and second gates 141 and 142, so that the reference levels of Q and R become Ql and R1, respectively. In other words, the line is set with a hysteresis corresponding to Q/1 and R'I in preparation for a transition in the opposite direction.

The exhaust cut valve actuation solenoid 240 is also controlled by a similar control circuit. In other words, for the intake air amount Q, the third comparison circuit 113 also calculates the engine speed R.
A fourth comparison circuit 114 is provided for this, and the outputs of these comparison circuits 113 and 114 are sent to the solenoid 240 via the second OR circuit 122. Third comparison circuit 1
Similarly, a third addition circuit 133 is provided for 13, and a fourth addition circuit 134 is provided for fourth comparison circuit 114. The set value Q3 is input to the third adder circuit 133, and Q10 (Q3+Q'3-Q4) is input via the third gate 143. Similarly, the fourth adder circuit 134 has a set value R3.
and R′3 (where R3
+R' 3 =R4) is input. Similarly, the fourth addition circuit 134 has a set value R3 and a fourth gate 144.
R'3 (where R3+R' 3 = Ri
) is input. This circuit operates in the same manner as the first and second comparison circuits described above, so that when transitioning to the high intake air amount region, the exhaust cut valve 223 is opened based on the Q4*R4 line in FIG. Furthermore, when shifting to the low intake air amount region, the valve 223 is closed by the Q 31 R3 line.

For the intake cut valve operating solenoid 238, the fifth
and the outputs of the sixth comparator circuits 115 and 116 are connected to the third O
A similar control circuit is provided which feeds through R circuit 123. This control circuit includes each comparison circuit 115
, 116, the fifth and sixth adder circuits 135, 13
6, 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 answer above. In other words, when transitioning to the high intake air amount region, Qs + R6
The intake cut valve opening control is performed by the lines Qs and Rs, and the intake cut valve closing control is performed by the lines Qs and Rs when transitioning to the low intake air amount region. Here, Q6 and R6 are similarly Qs +Q' 5-Q6. Rs +R'5-R6
It is set in the form of

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 this gate 147.

and the second OR circuit 12 for operating the exhaust cut valve.
A timer 150° is provided that starts counting up when the output of 2 changes from ON to OFF, and if the count value of this timer 150 exceeds a set value (for example, a value equivalent to 2 seconds), A seventh comparison circuit 117 that emits an ON signal is provided, and this seventh comparison circuit 117
When an ON signal is output from the seventh gate 14,
7 to forcefully close the intake cut valve 232,
At the same time, the standard values of Q and H were changed to Qs and Rs, and
The timer 150 is configured to be reset. - Once the seventh gate 147 is closed, the seventh comparison circuit 1
Although the output of 17 is turned off, since the reference value, which is the switching line, has been changed to 061R6 as described above, the intake cut valve operating solenoid 238 is maintained in the closed operating state. This prevents surging from occurring due to the intake cut valve solenoid 240 remaining in the ON state for a long time while the exhaust cut valve solenoid 238 is in the OFF state during the transition to the low intake air amount region.

Further, the wastegate valve solenoid 245 and the exhaust leakage valve solenoid 253 are 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 output signal of the OR circuit 122 is inputted to the comparison circuit 118. This comparison circuit 118 determines whether the output signal of the OR circuit 122 has changed from "ON" to "OFF".
It is determined whether the switch has changed from OFF to ON.
When the output signal of the R circuit 122 changes from OFF to ON, that is, when the exhaust cut valve 223 switches from a closed operation to an open operation, an OFF signal is output to the wastegate valve solenoid 245 and the exhaust leakage valve solenoid 253. wastegate valve 227 and exhaust leakage valve 23
Close 0. On the other hand, when the output signal of the OR circuit 122 changes from ON to OFF, that is, when the exhaust cut valve 223 switches from open operation to closed operation, the waste gate valve solenoid 245 and the exhaust leak valve solenoid 2
53 is stopped for a predetermined time T, and the waste gate valve 227 and the exhaust leak valve 230 are closed. Specifically, a timer 151 is connected to the comparison circuit 118, a ninth comparison circuit 119 is connected to the timer 151, and the output signal of this comparison circuit 119 is connected to the wastegate valve operating solenoid 245 and the exhaust leakage valve. It is input to the valve solenoid 253. Therefore, when the output signal of the OR circuit 122 changes from ON to OFF, the timer 151 starts counting up, and when this count value exceeds the set value T, an ON signal is output from the comparison circuit 119, and the wastegate valve 227 and Exhaust leak valve 230
operating force (permissible).The timer 151 is reset when the output signal of the OR circuit 122 changes from OFF to ON.

In the above configuration, the wastegate valve 227 and the exhaust leakage valve 230 operate as primary turbo supercharging a! 204
It functions as a relief means for relieving exhaust gas supplied to the turbine 205 of the primary turbocharger 204 according to the intake pressure downstream of the floor of the primary turbocharger 204 . Further, the control unit 246 controls the secondary turbo supercharger 2
It functions as a relief stop means that stops the operation of the relief means 227 for a predetermined period when the relief means 227 is switched from activated to inactive.

In the above embodiment, both the waste gate valve 227 and the exhaust leak valve 230 function as relief means,
When the secondary turbocharger 206 was switched from operating to inactive, both the wastegate valve 227 and the exhaust leakage valve 230 were closed for a predetermined period, but only one of the valves 227 and 230 functioned as a relief means. In this case, only one of the valves 227 and 230 may be closed for a predetermined period when the secondary turbocharger 206 is switched from operating to inactive.

(Effects of the Invention) As explained above, according to the control device for a turbocharged engine of the present invention, the primary and secondary exhaust gases each have a turbine in the exhaust passage provided in parallel with the engine. In an engine equipped with a turbo supercharger, in which the secondary turbo supercharger is operated only when the engine has a high intake air amount, depending on the intake pressure downstream of the proa of the primary turbo supercharger, a relief means for relieving the exhaust gas supplied to the turbine of the primary turbocharger; and a relief stop means for stopping the operation of the relief means for a predetermined period when the secondary turbocharger is switched from operation to non-operation. This allows the supercharging pressure to be well controlled according to the amount of intake air, and also maintains the exhaust pressure applied to the primary turbocharger turbine at a high level, for example when shifting up during acceleration or when accelerating again. Therefore, the turbo lag of the primary turbo supercharger is suppressed, and the primary turbo supercharger starts up smoothly and operates, thereby improving driving performance.

[Brief explanation of drawings]

The drawings illustrate an embodiment of the present invention; 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 response valve, and FIG. 4 is a diagram of the response valve. 5 is a control circuit diagram, and FIG. 6 is a time diagram showing each state quantity at the time of upshifting during acceleration. 202... Exhaust passage 203... Exhaust passage 204... Primary turbocharger 205... Turbine 206... Secondary turbocharger 211... Blower 223... Exhaust cut valve 227...・Wastegate valve (relief means) 230
...Exhaust leak valve (relief means) 246...Control unit (relief stop means) Fig.jli4 Fig.

Claims (2)

[Claims] (1) Equipped with a primary and secondary exhaust turbo supercharger each having a turbine installed in the exhaust passage provided in parallel with the engine, so that the secondary turbo supercharger is operated only when the engine has a high intake air amount. In the turbocharged engine according to the present invention, a relief means for relieving exhaust gas supplied to the turbine of the primary turbocharger according to the intake pressure downstream of the blower of the primary turbocharger; and a secondary turbocharger. 1. A control device for a turbocharged engine, comprising a relief stop means for stopping the operation of the relief means for a predetermined period when the engine is switched from operation to non-operation. (2) The exhaust passage dedicated to the secondary turbocharger is designed to supply exhaust gas to the turbine of the secondary turbocharger during open operation to operate the secondary turbocharger, and to operate the secondary turbocharger during closed operation. An exhaust cut valve is provided to cut off the supply of exhaust gas to the turbine and deactivate the secondary turbo supercharger, and the relief stop means is configured to stop the relief means when the exhaust cut valve switches from open operation to closed operation. The control device for a turbocharged engine according to claim 1, wherein the control device stops operation for a predetermined period.