JPH03115735A - Controller of engine with supercharger - Google Patents

Abstract

PURPOSE:To quickly activate a catalyst device by controlling opening operation of an exhaust cut valve when a temperature which relates to an exhaust catalyst device is low, in a device which opens the exhaust cut valve only at a high flow range of intake air so as to activate a secondary supercharger. CONSTITUTION:In a two-cylinder engine, turbines 105, 107 of primary and secondary turbosuperchargers 104, 106 are provided at two exhaust passages 102, 103 provided corresponding to cylinders, respectively. The two exhaust passages 102, 103 are communicated by a communication passage 112 at the upstream side of the turbines 105, 107. An exhaust cut valve 123 which is opened only at a high flow range of intake air is provided at the right down stream of a communication passage 122 opening position of secondary side exhaust passage 103. In this case, a temperature sensor 182 which detects temperature of exhaust gas is provided at a converged exhaust passage 124 located at the upstream of a catalyst device 181. Consequently, when the detected temperature is lower than a specified level, opening operation of the exhaust cut valve 123 is controlled.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a supercharged engine in which a plurality of superchargers are arranged in parallel.
Regarding the gin control device.

(Prior Art) Conventionally, as described in, for example, Japanese Unexamined Patent Publication No. 61-182421, two exhaust turbo superchargers, a primary turbo supercharger and a secondary turbo supercharger, are installed in parallel in an engine. , an exhaust cut valve is installed in the exhaust passage dedicated to the secondary turbocharger, and in the low intake air flow area (hereinafter referred to as the low intake air amount area), the exhaust cut valve is closed and the exhaust gas from the exhaust passage is routed to the primary turbocharger. High boost pressure is obtained by intensively supplying air to the turbine of the turbocharger, while the exhaust cut valve is opened in the high intake air flow range (hereinafter referred to as the high intake air flow range) to remove exhaust gas from the exhaust passage. A so-called sequential turbo engine is known, which supplies air to the turbines of a primary turbocharger and a secondary turbocharger to obtain an appropriate boost pressure while ensuring an amount of intake air.

(Problem to be solved by the invention) By the way, as one of the measures to purify engine exhaust gas,
2. Description of the Related Art There is a known technique for purifying exhaust gas by providing a catalyst device in an exhaust passage and using the catalyst device to promote oxidation of unburned components of the exhaust gas.

Such exhaust gas purification measures are also effective in the above-mentioned sequential turbo engine. However, in general, the catalytic device itself is fully active when it is at high temperature. Therefore, when the temperature of the catalytic device is low, such as immediately after starting the engine, the activation of the catalytic device is delayed and the exhaust gas purification function cannot be fully demonstrated.

The present invention has been made with attention to these points,
The purpose of this is that when a catalyst device is installed in a sequential turbo engine, when the temperature of the catalyst is low, exhaust heat is suppressed from being released from around the exhaust turbo supercharger and is introduced into the catalyst device. The goal is to raise the temperature of the exhaust gas.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, when the temperature related to the catalyst device is low, the exhaust gas is temporarily sent to the secondary turbine even in the high intake air amount region. By preventing this from flowing, the exhaust heat from around the secondary turbocharger is suppressed.

Specifically, the solution taken by the present invention is that a plurality of superchargers including an exhaust turbo supercharger are arranged in parallel in an engine, and at least one of the exhaust turbo superchargers is used as a secondary turbo supercharger. The turbocharger is equipped with an exhaust cut valve in the exhaust passage exclusively for the secondary turbo supercharger, and the exhaust cut valve is opened only in the high flow area of the intake air amount to operate the secondary turbo supercharger. Assuming an engine.

In response to this, a catalyst device for purifying exhaust gas provided in the exhaust passage downstream of the supercharger, a catalyst temperature detection means for detecting the temperature related to the catalyst device, and an output of the catalyst temperature detection means are detected. Accordingly, when the temperature related to the catalyst device is low, the exhaust gas cut valve is configured to be provided with a valve operation restriction means for restricting the opening operation of the exhaust cut valve.

(Function) With the above configuration, in the present invention, the exhaust cut valve closes in the low intake air amount region, the secondary turbocharger becomes inactive, and the engine is supercharged by the other supercharger. On the other hand, in the high intake air volume range, the exhaust cut valve opens and exhaust gas from the exhaust passage is supplied to the turbine of the secondary turbo supercharger, ensuring the intake air volume and achieving appropriate boost pressure. .

Further, since the catalyst device is provided in the exhaust passage downstream of the supercharger, the exhaust gas is purified.

In that case, based on the detection by the catalyst temperature detection means, the opening operation of the exhaust cut valve is restricted when the temperature related to the catalyst device is low by controlling the valve operation restriction means, even in the high intake air amount region. Exhaust gas temporarily stops flowing to the secondary turbine, suppressing the release of exhaust heat from around the secondary turbocharger. Therefore, the temperature of the exhaust gas introduced into the catalyst device becomes high, the catalyst device is quickly activated, and the exhaust gas purification function is satisfactorily exhibited.

(Example) The following will explain based on examples.

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

In this embodiment, the engine 101 is a reciprocating two-cylinder engine, and exhaust passages 102 and 103 are provided independently for each cylinder. A turbine 105 of a primary turbocharger 104 is disposed in one of the two exhaust passages 102 and 103, and a turbine 107 of a secondary turbocharger 106 is disposed in the other. Two exhaust passages 102, 10
3 merge into one downstream of both turbines 105 and 107 to form a combined exhaust passage 124.

The merging exhaust passage 124 is provided with a catalyst device 1 for purifying exhaust gas.
81 is provided. Further, a temperature sensor 182 for detecting the temperature of exhaust gas is provided in the combined exhaust passage 124 upstream of the catalyst device 181. The temperature sensor 18
2 functions as catalyst temperature detection means for detecting the temperature related to the catalyst device 181.

Further, the intake passage 109 is divided into two downstream of an air cleaner (not shown), and the blower 111 of the primary turbocharger 104 is located in the middle of the first branch passage 110, and the blower 111 of the primary turbo supercharger 104 is located in the middle of the second branch passage 112. A blower 113 of the secondary turbocharger 107 is installed. These branch passages 110° and 112 are formed so as to face each other at the branch part and to extend substantially straight on both sides. Also,
The two branch passages 110 and 112 are connected to each blower 111°11.
It rejoins downstream of 3. Then, an intercooler 114 is disposed in the intake passage 109, which has become one again, and a surge tank 115 is disposed downstream of the intercooler 114, and a throttle valve 116 is disposed between the intercooler 114 and the surge tank 115. It is set up. Further, the downstream end of the intake passage 109 branches into two independent intake passages 117 and 118 corresponding to each cylinder of the engine 101, and is connected to each intake port (not shown). Each of these independent intake/air passages 117, 118 has a fuel injection valve 119, respectively.
, 120 are arranged.

An air flow meter 121 is provided on the upstream side of the intake passage 109, located upstream of the branch of the first and second branch passages 110 and 112, and detects the amount of intake air.

The two exhaust passages 102 and 103 are communicated with each other by a relatively small diameter communication passage 122 upstream of both the primary and secondary turbochargers 104 and 105. In the exhaust passage 103 in which the secondary turbine 107 is disposed, an exhaust cut valve 123 is provided immediately downstream of the opening position of the communication passage 122. Also,
A turbine 10510 extends from the middle of the communication path 122.
7 Bypass passage 1 communicating with the downstream combined exhaust passage 124
25 is formed, and a wastegate valve 127 linked to a diaphragm type actuator 126 is disposed in the bypass passage 125. An exhaust passage 103 is connected to the upstream portion of the waste gate valve 127 of the bypass passage 125 and the secondary turbine 107.
Leakage passage 1 that communicates with the exhaust cut valve 123 downstream of
28 is formed, and the leakage passage 128 is provided with an exhaust leakage valve 130 linked to a diaphragm type actuator 129.

The exhaust cut valve 123 is linked to a diaphragm type actuator 131. On the other hand, the branch passage 1 in which the blower 113 of the secondary turbocharger 106 is disposed
12, an intake cut valve 132 is disposed downstream of the blower 113. This intake cut valve 132 is composed of a butterfly valve, and is also a diaphragm type actuator 1.
33. Further, a relief passage 134 is formed in the branch passage 112 on the secondary side so as to bypass the blower 113.
34 is provided with a diaphragm type intake relief valve 135.

Further, a shutter valve 183 is provided at the exhaust gas discharge port of the secondary turbine 107. The shutter valve 183 is a diaphragm type actuator 1.
84.

The actuator 12 that operates the exhaust leak valve 130
The pressure chamber 9 is connected via a conduit 136 to a branch passage 11 in which a blower 111 of the primary turbocharger 104 is disposed.
It is connected to the downstream side of the blower 111 of No. 0. When the pressure downstream of the blower 111 exceeds a predetermined value, the actuator 129 is actuated to open the exhaust leakage valve 130, thereby allowing a small amount of exhaust gas to pass through the bypass passage 128 when the exhaust cut valve 123 is closed. It flows and is supplied to the secondary turbine 107. Therefore, the secondary turbo supercharger [06] starts rotating before the exhaust cut valve 123 opens. During this time, since the intake relief valve is opened as will be described later, the rotation of the secondary turbo supercharger 106 increases, the transient response when the exhaust cut valve opens is improved, and the torque shock is alleviated.

The actuator 13 that operates the intake cut valve 132
The pressure chamber No. 3 is connected to an output port of an electromagnetic solenoid type three-way valve 138 by a conduit 137. Further, the actuator 131 that operates the exhaust cut valve 123 is
Another three-way valve 140 of electromagnetic solenoid type is connected by conduit 139.
connected to the output port of the Furthermore, the pressure chamber of the actuator 141 that operates the intake relief valve 135 is
Another three-way valve 143 of electromagnetic solenoid type is connected by conduit 142.
connected to the output port of the Intake relief valve 135
As will be described later, the relief passage 134 is closed until a predetermined time before the exhaust cut valve 123 and the intake cut valve 132 open.
Leave it open. As a result, the leak passage 128
Secondary turbo supercharger 10 by exhaust gas flowing through
6, the pressure upstream of the intake cut valve 132 rises and enters the surging region, and the rotation of the blower 113 is increased.

The actuator 126 operating the wastegate valve 127 is connected by a conduit 144 to the output port of another three-way valve 145 of the electromagnetic solenoid type.

The actuator for operating the shutter valve 183 is 1
84 is connected by a conduit 185 to the output port of another three-way valve 186 of the electromagnetic solenoid type.

The above five electromagnetic solenoid type three-way valves 138, 140.1
43, 145, and 186 are controlled by a control unit 1-146 configured using a microcomputer. This control unit 146 controls engine rotation speed R1, intake air mQ, and throttle opening TV.
O, the supercharging pressure Pl downstream of the primary side blower 111, etc. are input, and a signal from the temperature sensor 182 is also input manually, and based on these, control as described below is performed.

One input port of the electromagnetic solenoid type three-way valve 138 for controlling the intake cut valve 132 is connected to a negative pressure tank 148 via a conduit 147, and the other human-powered boat is connected to a negative pressure tank 148 via a conduit 147.
49 to the output port 17 of the differential pressure detection valve 150, which will be described later.
Connected to 0.

Intake negative pressure downstream of the throttle box 116 is introduced into the negative pressure tank 148 via the check valve 15. Further, one input port of the three-way valve 140 for controlling the exhaust cut valve is open to the atmosphere, and the other input port is
It is connected via a conduit 152 to the conduit 147 which is connected to the negative pressure tank 148 . On the other hand, one manual port of the three-way valve 143 for controlling the intake relief valve 135 is connected to the negative pressure tank 148, and the other manual port is connected downstream of the throttle valve 116 via a conduit 153. Further, one input port of the three-way valve 145 for controlling the wastegate valve 127 is open to the atmosphere, and the other input port is connected to the conduit 136 communicating with the downstream side of the primary side blower 111 through a conduit 154. has been done.

Furthermore, one input port of the three-way valve 186 for shutter valve control is open to the atmosphere, and the other manual boat is connected to the negative pressure tank 148 via a conduit 187.

As shown in FIG. 2, the differential pressure detection valve 150 has three chambers 164, 165, 1 formed by two first and second diaphragms 1,62, 163 in its casing 161.
It is divided into 66 sections. A first input port 167 is opened in the first chamber 164 at one end, and the inner surface of the end of the casing 161 and the first diaphragm 16
A compression spring 168 is disposed between the two. In addition, 16 second input ports are opened in the second chamber 165 in the middle, and in the third chamber 166 on the other end side, an output port 170 is opened in the center of the end wall of the casing 161, and an output port 170 is opened in the side wall. The atmosphere release boat 171 is opened. The first diaphragm 162 includes a second diaphragm 16.
A valve body 172 is fixedly provided, passing through the third chamber 166 and extending toward the output port 170 of the third chamber 166.

The first input port 167 is connected by a conduit 173 to a first
As shown in the figure, it is connected to the downstream side of the intake cut valve 132, and introduces the supercharging pressure P on the downstream side of the primary side blower 111 into the first chamber 164.

Further, the second human-powered boat 169 is connected to the upstream side of the intake cut valve 132 by a conduit 174, and therefore introduces the pressure P2 upstream of the intake cut valve 132 when the intake cut valve 132 is closed. There is. When the difference between the pressures PI and P2 introduced from the two human power ports 167 and 169 is greater than a predetermined value, the valve body 172
Open 0.

This output port 170 is connected via a conduit 149 to one of the input ports of a three-way valve 138 for controlling the intake cut valve 132. Therefore, with the three-way valve] 38 communicating the conduit 137 connected to the pressure chamber of the actuator 133 for operating the intake cut valve 132 with the conduit 149 connected to the output port of the differential pressure detection valve 150, the differential pressure P
When 2-PL becomes larger than a predetermined value, the atmosphere is introduced into the actuator 133, and the intake cut valve 132 is opened. In addition, the three-way valve 138 connects the conduit 137 on the actuator 133 side to the conduit 1 that connects to the negative pressure tank 148.
47, negative pressure is supplied to the actuator 133 and the intake cut valve 132 is closed.

On the other hand, in the exhaust cut valve 123, when the three-way valve 140 for controlling the exhaust cut valve 123 connects the conduit 139 connected to the pressure chamber of the actuator 131 for operating the exhaust cut valve 123 to the conduit 152 on the negative pressure tank 148 side, It is closed by supplying negative pressure to the actuator. Furthermore, when the three-way valve 140 releases the conduit 139 on the output side to the atmosphere, the exhaust cut valve 123 is opened and supercharging by the secondary turbo supercharger 106 is performed.

FIG. 3 shows an intake cut valve 132, an exhaust cut valve 123,
This is a control map showing the open/close states of the intake relief valve 135 and the waste gate valve 127 as well as the open/close states of the exhaust leak valve 130. This map is stored in the control unit 146, and based on this map, the four electromagnetic solenoid type three-way valves 138, 140, 143.
45 controls are performed.

In a low intake air amount region where the engine speed R is low or the intake air amount Q is small, the intake relief 135 is open, and the exhaust leak valve 130 opens to pre-rotate the secondary turbo supercharger 106. be exposed. Then, when the engine speed reaches R2 or the intake air amount reaches the line Q2, the intake relief valve 135 is closed.
After that, the pressure downstream of the secondary blowers 11 and 3 increases until the exhaust cut valve 123 opens. And Q
When the line 4-R4 is reached, the exhaust cut valve 123 opens, and then when the line Q6-R6 is reached, the intake cut valve 13 is opened.
2 opens, supercharging by the secondary turbo supercharger 106 begins, and the system enters a supercharging region by both the primary and secondary superchargers at the Q6-46 line.

The intake cut valve 132, the exhaust cut valve 123, and the intake relief valve 135 have a slight hysteresis from the high intake air amount area to the low intake air amount area, that is, Q5-R5, Q3R3, Ql shown by broken lines in FIG. - Switches on each line of R1.

Note that the bent portions of each of these lines are on the so-called no-load line or load-load line.

The wastegate valve 127 is opened when the engine speed R and the throttle opening TVO are greater than or equal to a predetermined value and the boost pressure P1 downstream of the primary side blower is greater than or equal to a predetermined value.

Further, when the exhaust gas temperature detected by the temperature sensor 182 is lower than a predetermined value, as shown in FIG.
Exhaust cut valve 123 and intake cut valve 1 for steady state
By shifting the timing of opening 32 to the high flow rate and high rotation side,
The operating range in which the secondary turbocharger 106 operates is narrowed. However, the closing timing of the intake relief valve 135 remains unchanged.

Furthermore, ■ the engine 101 is started within 2 minutes; ■ the temperature of the intake air is below 0 degrees Celsius; ■ the temperature of the cooling water of the engine 101 is below 0 degrees Celsius;
When all of the above apply, the three-way valve 186 is turned ONL to close the shutter valve 183 and the exhaust leakage valve 130 to perform rapid warm-up (AWS).

FIG. 5 is a flowchart for executing the above-mentioned control of the intake cut valve 123, the exhaust cut valve 132, and the intake relief valve 135 in this embodiment.

Note that S indicates each step. Furthermore, F is a flag, and the meanings of the flag states (F-1 to F-6) are as shown in Figure 3. Transition from the flow rate side to the low flow rate side (F-1), CF-2), the transition from the low flow 2 side of the Q2-R2 line to the high flow rate side, Q3-R
This is the transition from the high flow rate side to the low flow rate side of the 3rd line (F
-3), transition from the low flow rate side to the high flow rate side of the Q4-R4 line (F~4), transition from the high flow rate side to the low flow rate side of the Q5-R5 line (F-5), This is the transition from the low flow rate side to the high flow rate side of the Q6-R6 line (F-6)
, corresponds to each state. The steps will be explained below.

First, starting from FIG. 5, initialization is performed at Sl. At this time, the flag is set to 1.

Next, in S2, intake air mQ and engine speed R are input. Then, in S3, the map values Q1 to Q6. R1~R
Read out 6.

Next, in S4, it is determined whether the engine 101 is in a state where rapid warm-up (AWS) should be performed based on the above three determinations (1) to (2). When it is determined that rapid warm-up (AWS) is required, the shutter valve 183 is activated in S36.
, close the exhaust leak valve 130 in S37, and return.

On the other hand, when it is determined in S4 that the state is not such that rapid warm-up (AWS) should be performed, the shutter valve 183 is opened in S5 and the process proceeds to S6.

In step 86, it is determined whether the temperature of the catalyst device 181 is lower than a predetermined value based on the exhaust gas temperature detected by the temperature sensor 182. If the temperature of the catalyst device 181 is higher than the predetermined value, the process directly advances to S8. On the other hand, when the H degree of the catalyst device 181 is lower than the predetermined value, S
Proceed to step 7 and install the exhaust cut valve 123 and intake cut valve 132.
Q4, which corresponds to the opening timing of Q4. Q6. R4 and R6 are each set to a predetermined value ΔQ4. Q6. Increase correction by R4 and R6. Then go to 88.

In S8, it is checked whether the flag F is 1, that is, whether the previous transition was from the high flow rate side to the low flow rate side of the Ql-R1 line. Note that initially it is F-1, so this determination is YES.

Then, if it is F-1, then go to S9 and this time Q
is greater than Q2, N.

If so, then SIO checks whether R is larger than R2 this time. Then, select YES in S9 or Y in S10.
If it is ES, go to Sll, set flag F to 2, and control to close the intake relief valve in S12 (introduce positive pressure to the actuator). Further, if the determinations in S9 and 510 are both No, the process directly returns.

If the determination in S8 is No, go to 313 and check whether the flag F is an even number, that is, whether the previous transition was from the low flow rate side to the high flow rate side on any line. I see.

If 313 is YES, go to S14 and F-
2, that is, whether the previous transition was from the low flow rate side to the high flow rate side of the Q2-R2 line. If F-2, the process goes to S15.

In S15, it is determined whether Q is greater than Q4 this time, and if NO, then in S16 it is determined whether R is greater than R4 this time. If either S15 or S16 is YES, go to S17 and flag F.
is set to 4, and the exhaust cut valve is controlled to open at 818 (negative pressure is introduced into the actuator).

Further, both determinations in S15 and S16 are N.

If so, go to S19 and check whether QIJ<Ql is smaller this time.

If YES in S19, it is checked in S20 whether R is smaller than R co- this time. And if YES, S2
1 to set flag F to 1, and in S22 control to open the intake relief valve (introduce negative pressure to the actuator). Also, both the determinations of S1.9 and S20 are N.
If o, return as is.

If the determination in S14 is NO, go to S23 and check whether the flag is F or 4, that is, whether it was the previous transition or Q4-R.
It is determined whether there has been a transition from the low flow rate side to the high flow rate side of the 4th line.

If YES in 323, it is checked in S24 whether Q is greater than Q6 this time, and if NO, then it is checked in S25 whether R is greater than R6 this time. And S24
Alternatively, if YES in either S25, the process goes to S26 and sets the flag F to 6, and in S27 the intake cut valve is controlled to open (the actuator is communicated with the differential pressure detection valve side).

Also, if No in S25, go to 328 and select Q or Q3.
Determine whether it is smaller than the value, and if YES, S29
It is determined whether R is smaller than R3. And S
If YES in 29, go to S30 and set flag F to 3, and control to close the exhaust cut valve in S31 (
(introducing atmospheric air into the actuator).

If the determination in S23 is No, it means that F-6, that is, the previous transition was from the low flow rate side of the Q6-R6 line to the high position m side, and in this case, go to S32. It is determined whether Q is smaller than Q5 this time, and if YES, then in S33 it is determined whether R is smaller than R5 this time. If YES, go to S34, set flag F to 5, and control to close the intake cut valve (introduce negative pressure to the actuator) in S35.
. Further, if the answer is No in either S32 or 333, the process returns directly.

Next, the flow when the determination at 813 is No will be explained.

If No in S1B, the process goes to S41 to determine whether flag F is 3, that is, whether the previous transition was from the high flow rate side to the low flow rate side of the Q3-R3 line. If YES, then in S42 it is determined whether Q is smaller than Ql this time, and if YES, 3
In step 43, it is determined whether R is smaller than R1 this time. If YES, the process goes to S44 to set flag F to 1, and then, in S45, control is performed to open the exhaust gas cut valve.

If No in either S42 or 543, S4
6, it is checked whether Q is greater than Q4, and if No, it is determined whether R is greater than R4 at step S47. Then, select YES in either S46 or S47.
If so, the process goes to S48 to set the flag F to 4, and then, in 849, controls to open the exhaust cut valve. Also, S
If the answer is No at 47, the process returns directly.

If No in S41, it means F-5, and in this case, go to S50 to determine whether Q is smaller than Q3, and if YES, go to 551 to determine whether R is smaller than R3. do. If YES in S51, flag F is set to 3 in S52, and then υ is set in S53.
1. Controls the closing of the air cut valve.

If No in either S50 or S51, S5
Go to step 4 to determine whether Q is greater than Q6, and select No.
If so, then it is checked in S55 whether R is greater than R6. If YES in either S54 or S55, the process goes to S56 to set flag F to 6, and then, in S57, control is performed to open the intake cut valve.

Further, if the answer is No in S55, the process directly returns.

In the above flow, in S6 and S7, the output of the catalyst temperature detection means (7M degree sensor) 182 is received, and when the temperature related to the catalyst device 181 is low, the exhaust cut valve 1
It constitutes a valve operation limiting means 191 that limits the opening operation of 23.

Therefore, in the above embodiment, the exhaust cut valve 123 is closed in the low intake air amount region, and the exhaust passage 102.1.0 is closed.
3 is intensively supplied to the turbine 1.05 of the primary turbocharger 104 to obtain high boost pressure. On the other hand, in the high intake air low range, the exhaust cut valve 123 opens and the exhaust gas from the exhaust passages 102 and 103 is supplied to the turbines 105 and 107 of the primary turbo supercharger 104 and the secondary turbo supercharger 106 to reduce the intake air amount. Appropriate boost pressure can be obtained while ensuring the

Further, when the temperature of the catalyst device 181 is lower than a predetermined value, Q4. Q6. R4°R6 are set to predetermined values ΔQ4. Q6. Since the increase correction is made by R4 and R6, the operating range in which the secondary turbocharger 106 is inactive is expanded. As a result, even in the high intake air amount range, exhaust gas temporarily stops flowing to the secondary turbine 107, and the release of exhaust heat from around the secondary turbocharger 106 is suppressed. Therefore, the temperature of the exhaust gas introduced into the catalyst device 181 becomes high, the catalyst device 181 is quickly activated, and the exhaust gas purification function is satisfactorily exhibited.

Furthermore, when it is determined that the engine 101 is in a state where rapid warm-up (AWS) should be performed, the shutter valve 183
Since the exhaust gas leak valve 130 is closed, exhaust gas can be prevented from flowing into the turbine 107 of the secondary turbo supercharger 106, which is inactive due to the low intake air amount region. It is possible to suppress the release of exhaust heat from around the side turbine. In this case as well, the catalyst device 18
The temperature of the exhaust gas introduced into the catalyst device 181 becomes high, the catalyst device 181 is quickly activated, and the exhaust gas purification function is effectively exhibited.

In the above embodiment, there are two superchargers, both of which are exhaust turbo superchargers, but the number of superchargers may be three or more. It is sufficient if at least one of the feeders is an exhaust turbo supercharger.

(Effects of the Invention) As explained above, according to the control device for a supercharged engine of the present invention, a plurality of superchargers including an exhaust turbo supercharger are arranged in parallel in the engine, and At least one exhaust turbo supercharger is used as a secondary turbo supercharger, and an exhaust cut valve is provided in the exhaust passage dedicated to the secondary turbo supercharger, and the exhaust cut valve is opened only in the high flow region of the intake air amount to operate the secondary turbo. A catalyst device for purifying exhaust gas provided in an exhaust passage downstream of the turbocharger, a catalyst temperature detection means for detecting a temperature related to the catalyst device, and a catalyst temperature detection means for detecting a temperature related to the catalyst device while operating the supercharger. A valve operation limiting means is provided that receives the output and limits the opening operation of the exhaust cut valve when the temperature related to the catalyst device is low, so the secondary turbo supercharger can be activated or deactivated according to the amount of intake air. While enabling switching and exhaust gas purification, it also activates the catalytic converter quickly by suppressing the release of exhaust heat from around the secondary turbocharger even when the temperature associated with the catalytic converter is low, such as immediately after startup. Exhaust gas can be effectively purified.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is an overall system diagram, Fig. 2 is a sectional view of a differential pressure detection valve, Figs. 3 and 4 are control characteristic diagrams, and Fig. 5 is a diagram showing control execution. FIG. 101...Engine] 04...Primary turbo supercharger 106...Secondary turbo supercharger 123...Exhaust cut valve 181...Catalyst device 182...Temperature sensor (catalyst temperature detection means) 183・
...Shutter valve 191... Valve operation limiting means Fig. 2

Claims (1)

[Claims] (1) A plurality of superchargers including an exhaust turbo supercharger are arranged in parallel in the engine, and at least one of the exhaust turbo superchargers is designated as a secondary turbo supercharger, and is dedicated to the secondary turbo supercharger. In a supercharged engine that is equipped with an exhaust cut valve in the exhaust passage, and is configured to open the exhaust cut valve only in the high flow region of intake air to operate the secondary turbo supercharger, the exhaust passage downstream of the supercharger a catalyst device for purifying exhaust gas provided in the catalytic converter; a catalyst temperature detecting means for detecting a temperature related to the catalyst device; and a catalyst temperature detecting means for detecting a temperature related to the catalyst device; 1. A control device for a supercharged engine, comprising valve operation limiting means for limiting the opening operation of a cut valve.