JPH0518256A - Control device for engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent the occurrence of hunting occasioned by switching by switching a plurality of superchargers according to the operation state of an engine and to improve acceleration response from a steady running state by operating only a part of the superchargers when the number of revolutions of an engine is kept at a given value for a specified time. CONSTITUTION:Primary and secondary superchargers 204 and 206 are formed such that turbines 205 and 207 are disposed in exhaust gas passages 202 and 203, respectively, of an engine 201 and blowers 211 and 213 are disposed in branch passages 210 and 212, respectively, of an intake air passage 209. Operation of the superchargers 204 and 206 is controlled according to the load of the engine 201 by a control unit 246 through an exhaust cut valve 223 and a suction cut valve 232. In this case, the first number of revolutions of the engine 201 causes total operation of superchargers 204 and 206 and the second number of revolutions being lower than the first number of revolutions causes partial operation the superchargers 204 and 206, and partial operation of superchargers 204 and 206 is carried out between the first and second numbers of revolutions after a lapse of a given time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an engine with a supercharger in which a plurality of superchargers are arranged in parallel (sequential turbo).

[0002]

2. Description of the Related Art A conventional twin turbo type engine, that is, two primary and secondary exhaust turbochargers are installed in parallel in the engine, and an exhaust cut valve and an intake cut valve are provided in the secondary turbocharger. In the low intake air amount range, only the turbocharger on the primary side performs supercharging, and in the high intake air amount range, both turbochargers supercharge the engine. Prevents backflow of intake air to the high intake air amount side turbocharger when transitioning to the air amount region, and prevents high intake air amount side turbocharger when shifting from the high intake air amount region to the low intake air amount region. The following controls are performed to prevent surging of the feeder. That is, when the operating state of the engine shifts from the low intake air amount range to the high intake air amount range, the intake cut valve is opened later than the exhaust cut valve, and the high intake air amount range is changed to the low intake air amount range. When shifting to the region, the supercharger control with hysteresis is performed so that the intake cut valve closes later than the exhaust cut valve.

[0003]

However, in the conventional control of the supercharger described above, when the engine is in a steady running state when the operating state of the engine changes from the high intake air amount region to the low intake air amount region, Supercharging control by only the turbocharger on the primary side when supercharging continues in both primary and secondary turbochargers despite a low load, or when re-accelerating from a steady running state Contrary to the better acceleration response in the state, supercharging control by both the primary and secondary turbochargers is executed.

This is because the supercharger should originally be supercharged only by the turbocharger on the primary side at the time of low load or acceleration from a steady running state, but the turbocharger on the secondary side also operates, so that the secondary side is operated. The turbocharger has a problem in that cost rises and deterioration in acceleration response performance is unavoidable due to selection of materials and the like according to its operating state.

[0005]

The present invention has been made for the purpose of solving the above-mentioned problems, and is provided with the following structure as means for solving the above-mentioned problems. That is, a plurality of exhaust turbochargers are arranged in parallel in the intake passage, and a supercharger for switching control of the plurality of exhaust turbochargers is made to correspond to a region preset according to the engine load. In a control device for an engine, in an area corresponding to a first engine speed, switching from a state in which a part of the plurality of exhaust turbochargers is operating to a state in which a full exhaust turbocharger is activated Switching means and a region corresponding to a second engine speed equal to or lower than the first engine speed, from the state in which the full exhaust turbocharger is operating by the switching by the first switching means. A second switching means for switching a part of the plurality of exhaust turbochargers to an operating state, and the first switching means for operating the all exhaust turbocharger with the first switching means. When a region corresponding to the engine rotation speed between the engine rotation speed and the second engine rotation speed is reached, a part of the plurality of exhaust turbochargers is switched to an operating state after a predetermined time. And switching means. Preferably, the switching after the predetermined time by the third switching means is performed when the engine load is equal to or less than the predetermined value.

[0006]

With the above structure, hunting is prevented during switching of the turbocharger and the acceleration response from the steady running state is improved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. <Description of Overall Configuration> FIG. 1 shows the overall configuration of a control device for an engine with a supercharger (hereinafter referred to as a device) according to an embodiment of the present invention. In the engine shown in the figure, the exhaust passage of each cylinder is independently guided to the turbines of both the primary and secondary exhaust turbochargers, so that the exhaust engine is driven in the region where supercharging is performed by both exhaust turbochargers. The pressure is effectively applied to both turbines to improve the supercharging efficiency.

As described above, the exhaust passages 202 and 203 of each cylinder of the engine 201 are provided independently of each other.
The primary turbocharger 2 is installed in one of these exhaust passages.
The turbine 205 of No. 04 and the turbine 207 of the secondary turbocharger 206 are arranged on the other side. Both exhaust passages are connected to the turbines 205, 20.
7 merges downstream and is connected to a silencer (not shown).

The intake passage 209 branches in two directions downstream of an air cleaner (not shown), and the first branch passage 21
A blower 211 of the primary turbocharger 204 is arranged in the middle of 0, and a blower 213 of the secondary turbocharger 206 is arranged in the middle of the second branch passage 212. These branch passages are formed so as to face each other at the branch portion and extend substantially straight on both sides.
They join again downstream of the blowers 211 and 213. An intercooler 214 is provided in the intake passage 209 after joining, a surge tank 215 is provided downstream thereof, and a throttle valve 216 is provided between the intercooler 214 and the surge tank 215. Further, the intake passage 209
The downstream end of the branch is branched into two independent intake passages 217 and 218 corresponding to each cylinder of the engine 201, which are connected to each intake port (not shown). Fuel injection valves 219 and 220 are arranged in these independent intake passages, respectively.

On the upstream side of the intake passage 209, the first,
An air flow meter 221 for detecting the intake air amount is provided upstream of the branch portion of the second branch passage. The exhaust passages 202 and 203 are connected to each other by a communication passage 222 having a relatively small diameter upstream of both the primary and secondary turbochargers 204 and 206. In the exhaust passage 203, in which the secondary turbine 207 is arranged, an exhaust cut valve 223 is provided immediately downstream of the opening position of the communication passage 222. Further, a bypass passage 225 that communicates with the combined exhaust passage 224 downstream of the turbines 205 and 207 is formed in the middle of the communication passage 222, and in this bypass passage, the waste gate valve 22 connected to the diaphragm type actuator 226 is formed.
7 are provided.

The upstream portion of the waste passage valve 227 of the bypass passage 225 and the downstream portion of the exhaust cut valve 223 of the exhaust passage 203 connected to the secondary turbine 207 are communicated with each other through a leakage passage 228, and the leakage passage has a diaphragm. An exhaust leak valve 230 is provided which is connected to a conventional actuator 229. The exhaust cut valve 223 is a diaphragm type actuator 231.
Are linked to.

Blower 2 of the secondary turbocharger 206
An intake cut valve 232 is arranged downstream of the blower 213 in the branch passage 212 in which 13 is arranged. The intake cut valve 232 is composed of a butterfly valve and is connected to a diaphragm type actuator 233. Further, a relief passage 234 is formed in the branch passage 212 so as to bypass the blower 213, and a diaphragm type intake relief valve 235 is arranged in the relief passage.

The pressure chamber of the actuator 229 is connected via a conduit 236 to the downstream side of the blower 211 of the branch passage 210 in which the blower 211 of the primary turbocharger 204 is arranged. Therefore, when the pressure downstream of the blower 211 exceeds a predetermined value with the exhaust cut valve 223 closed, the actuator 229 operates and the exhaust leakage valve 230 opens, so that a small amount of exhaust gas passes through the bypass passage 22.
8 and is supplied to the turbine 207 on the secondary side. Therefore, the secondary turbocharger 206 starts rotation (called pre-rotation) before the exhaust cut valve 223 opens. During this period, the rotation of the secondary turbocharger 206 is increased because the intake relief valve 235 is opened.

A pressure chamber of an actuator 233 which operates the intake cut valve 232 is connected to an output port of an electromagnetic solenoid type three-way valve 238 by a conduit 237. In addition, the actuator 23 that operates the exhaust cut valve 223
1 is an electromagnetic solenoid type three-way valve 240 through a conduit 239.
Connected to the output port of. Further, the pressure chamber of the actuator 241 which operates the intake relief valve 235,
The conduit 242 is connected to the output port of the electromagnetic solenoid type three-way valve 243. Then, the intake relief valve 23
5 is that by opening the relief passage 234 until a predetermined time before the exhaust cut valve 223 and the intake cut valve 232 are opened, the secondary turbocharger 206 is pre-rotated by the exhaust gas flowing through the leak passage 228. When doing so, the rise of the pressure upstream of the intake cut valve 232 is suppressed, and the rotation of the blower 213 is raised. An actuator 226 that operates the wastegate valve 227 is connected to an output port of an electromagnetic solenoid type three-way valve 245 by a conduit 244.

The control unit 246 is a built-in micro computer, and in accordance with a control map described later, the electromagnetic solenoid type three-way valves 238, 240, 2 described above.
43 and 245 are controlled. This control unit 2
The output signal of the engine speed sensor (not shown), the output signal of the air flow meter 221, the throttle opening, the supercharging pressure downstream of the primary side blower 211, etc. are further input to 46, and predetermined control is performed based on them. Do.

One input port of the electromagnetic solenoid type three-way valve 238 for controlling the intake cut valve 232 is connected to the negative pressure tank 248 via the conduit 247, and the other input port is connected to the differential pressure detection valve 250 via the conduit 249. Connected to the output port of. Intake negative pressure downstream of the throttle valve 216 is introduced into the negative pressure tank 248 via the check valve 251. Also, a three-way valve 24 for controlling the exhaust cut valve is used.
One input port of 0 is open to the atmosphere, and the other input port of 0 is connected to a conduit 247 connected to a negative pressure tank 248 via a conduit 252.

One input port of the three-way valve 243 which operates the intake relief valve 235 is connected to the negative pressure tank 248, and the other input port is open to the atmosphere. Also,
One input port of the three-way valve 245 that operates the wastegate valve 227 is also open to the atmosphere, and the other input port is connected by a conduit 254 to a conduit 236 communicating with the downstream side of the blower 211 on the primary side.

<Description of Differential Pressure Detection Valve, etc.> FIG. 2 shows a sectional structure of the differential pressure detection valve 250 in the apparatus of this embodiment. As shown in the figure, the differential pressure detection valve is divided into three chambers 264 to 266 by the first and second diaphragms 262 and 263. Then, a first input port 267 is opened in the first chamber 264, and the casing 261 is also provided.
A compression spring 268 is disposed between the inner surface of the end of the first diaphragm and the first diaphragm. The second input port 269 opens in the second chamber 265, and the third chamber 266 is opened.
The output port 270 is open at this position. Further, an atmosphere opening port 271 is opened on the side wall of the casing.

The first diaphragm 262 has a second
A valve body 272 is fixedly provided, which penetrates the diaphragm 263 of FIG. 1 and extends toward the output port 270 opening to the third chamber 266. The first input port 267 is connected to the downstream side of the intake cut valve 232 by a conduit 273, and introduces the supercharging pressure (referred to as P1) on the downstream side of the primary side blower 211 into the first chamber 264. In addition, the second input port 26
9 is connected to the upstream side of the intake cut valve 232 by a conduit 274, and when the intake cut valve 232 is closed, introduces the pressure (P2) on the upstream side. Pressures P1 and P2 introduced from these input ports 267 and 269
If the difference between the two exceeds a predetermined value, the valve body 272 will cause the output port 2
Open 70.

Output port 270 is connected via conduit 249 to one of the input ports of a three-way valve 238 which operates intake cut valve 232. Therefore, this port 270
Is connected via conduit 249 to one of the input ports of a three-way valve 238 which actuates intake cut valve 232.
Therefore, when the three-way valve 238 is ON, the intake cut valve 23
In the state where the conduit 237 connected to the pressure chamber of the two-actuator 233 is connected to the conduit 249 connected to the output port of the differential pressure detection valve 250, the boost pressure P2
Becomes closer to the supercharging pressure P1 and the differential pressure P1-P2 disappears, and when the differential pressure P2-P1 becomes larger than a predetermined value, the atmosphere is introduced into the actuator 233 and the intake cut valve 23
2 is opened. Further, when the three-way valve 238 is turned off, the conduit 237 on the actuator 233 side is connected to the negative pressure tank 248.
When communicating with the conduit 247 connected to, the negative pressure is supplied to the actuator 233 and the intake cut valve 232 is closed.

In the exhaust cut valve 223, the three-way valve 240 is O.
Conduit 2 connected to the pressure chamber of actuator 231 by FF
When 39 is made to communicate with the conduit 252 on the negative pressure tank 248 side, the negative pressure is supplied to the actuator 231 to close it. Further, when the three-way valve 240 is turned on and the conduit 239 on the output side is opened to the atmosphere, the exhaust cut valve 223 is opened and the secondary turbocharger 206 performs supercharging.

Further, the intake relief valve 235 is the three-way valve 2
When 43 is OFF and the conduit 242 connected to the pressure chamber of the actuator 241 is communicated with the negative pressure tank 248 side,
It is opened when negative pressure is supplied to the actuator 241.
Further, the intake relief valve 235 is closed when the three-way valve 243 is ON and the conduit 242 connected to the pressure chamber of the actuator 241 is opened to the atmosphere.

The actuator 226 for operating the wastegate valve 227 communicates with the downstream of the primary side blower 211 via the conduits 254 and 236 when the three-way valve 245 is ON. Further, when the three-way valve 245 is off, the actuator 226 is open to the atmosphere.

<Explanation of Supercharger Control> Next, the supercharger control in the apparatus according to the present embodiment will be described in detail. FIG. 3 is a control map showing the relationship between the opening and closing of the exhaust cut valve and the operating state of the engine in the apparatus according to the embodiment. In the figure, the intake relief valve 235 is opened in the region where the engine speed R is low or the intake air amount Q is low in the process in which the operating state of the engine shifts from the low intake air amount side to the high intake air amount side. Exhaust leak valve 230
Is opened, pre-rotation of the secondary turbocharger 206 is performed. Then, when the engine speed or the intake air amount further increases, the intake relief valve 235 is closed, and then the exhaust cut valve 223 as described later.
The pressure downstream of the secondary-side blower 213 rises until is opened.

The engine speed or the intake air amount is Q
When reaching the 2-R2 line, first the exhaust cut valve 223
Is opened, and then the intake cut valve 232 is opened,
Supercharging by the secondary turbocharger 206 is started. That is, in the area C that exceeds the Q2-R2 line, supercharging is performed by both the primary and secondary superchargers.

On the other hand, when the engine operating state shifts from the high intake air amount side to the low intake air amount side, the engine speed,
Alternatively, when the intake air amount exceeds the line Q2-R2, that is, when the region C enters the region B, a timer described later is started. When the engine speed or the intake air amount exceeds the Q1-R1 line, the exhaust cut valve 223 is closed first, and then the intake cut valve 232 is closed to control the intake cut valve 232. Then, the opening control of the intake relief valve 235 is performed after that.
That is, when the vehicle enters the area A beyond the Q1-R1 line, the supercharging by only the primary turbocharger 204 is started.

Therefore, according to the flow chart shown in FIG. 4, of the supercharger control in the apparatus according to the present embodiment, the supercharger control procedure at the time of shifting from the high intake air amount side to the low intake air amount side. explain. At step S1 in FIG.
The control unit 246 detects operating conditions such as the intake air amount and the engine speed. In step S2, it is determined whether or not the driving state has entered the B region beyond the Q2-R2 line from the C region shown in FIG. If it is determined that the operating state has entered the B range, the control unit 246 activates the timer in the subsequent step S3. Then, in step S4, the load condition of the engine is
It is determined whether or not the set value Qp shown in FIG.

When the determination in step S2 is NO, that is, the operating state remains in the C range, or when the determination in step S4 is NO, that is, when the load exceeds the set value (Q2-
Even if it exceeds the R2 line, if it is not within the shaded area in the figure), the process is terminated. That is, the process returns with the supercharging control performed by both the primary and secondary superchargers.

If the decision result in the step S4 is YES, a step S5 decides the elapsed time after the operating state enters the B range. That is, it is determined whether or not the count value by the timer started in step S3 exceeds a predetermined count number. If it is determined here that the operating state in the B region has not exceeded the predetermined time, the process proceeds to step S6 to determine whether the operating state has entered the A region.

However, if it is determined in step S5 that a predetermined time has elapsed while the operating condition is in the B range, or if it is determined in step S6 that the operating condition is in the A range, then step S8 is entered. Then, the supercharging control by both the primary and secondary superchargers is shifted to the supercharging control by only the primary supercharger 204. In other words, step S
At 8, the control unit 246 controls the closing of the exhaust cut valve 223, the closing control of the intake cut valve 232, and the opening control of the intake relief valve 235.

On the other hand, if the determination in step S6 is NO, it is determined in step S7 whether the operating condition has returned from the B range to the C range. If the determination here is YES, the process is directly returned and the supercharging control state by both the primary and secondary superchargers is maintained. However, if it is determined in step S7 that the operating condition has not returned to the C range, the process is returned to step S5 again.

The operating condition in the B range is, for example,
This corresponds to steady running on a highway, and when such a low load state continues for a certain period, the supercharge control state by both the primary and secondary superchargers is changed to the supercharge control by only the primary side supercharger. In addition, the operating state is C
Even if it exceeds the Q2-R2 line from the region, when it is not within the shaded region in FIG. 3, that is, when the load is high, the timer is not started, and accordingly, the supercharge control state by both the primary and secondary superchargers By continuing the above, the occurrence of torque shock due to switching of the turbocharger at high load is prevented.

As described above, according to this embodiment,
When the opening and closing control of the exhaust cut valve is given a hysteresis corresponding to the operating state, and when transitioning from the high intake air amount side to the low intake air amount side, if the low load condition continues for a certain period, both the primary and secondary preset By switching the supercharger control by the primary turbocharger only by closing the exhaust cut valve before reaching the switching point from the supercharger control by the supercharger to the supercharger control by only the primary turbocharger. It is possible to prevent hunting at the time of switching the feeder, improve acceleration response from steady running, and prevent torque shock caused by switching the turbocharger in the high load region.

Further, by switching to the supercharging control only by the primary turbocharger when the load is low, it is possible to avoid unnecessary increase in the frequency of use of the secondary turbocharger, and the secondary turbocharger and its control. There is also an effect that the cost of materials such as valves related to can be reduced according to the frequency of use.

[0035]

As described above, according to the present invention,
By switching the exhaust turbo supercharger according to the engine operating state, hunting accompanying it is prevented, and when it is within a predetermined engine speed region for a certain period of time, only a part of the supercharger is switched to operate. As a result, the acceleration response from the steady running state can be improved. Further, by performing the switching only when the load is equal to or less than the predetermined load, it is possible to prevent the torque shock due to the switching under the high load.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a control device for an engine with a supercharger according to an embodiment of the present invention,

FIG. 2 is a diagram showing a cross-sectional configuration of a differential pressure detection valve in the device of the present embodiment,

FIG. 3 is a control map showing the relationship between the opening and closing of the exhaust cut valve and the operating state of the engine in the apparatus according to the embodiment.

FIG. 4 is a flow chart showing a supercharger control procedure when shifting from a high intake air amount side to a low intake air amount side in the device according to the embodiment.

[Explanation of symbols]

201 engine body 203 Exhaust passage 204 Primary turbocharger 206 Secondary turbocharger 221 Air Flow Meter 222 communication passage 223 Exhaust cut valve 228 Leakage passage 232 Intake cut valve 246 control unit 250 Differential pressure detection valve

Claims (2)

[Claims] 1. A plurality of exhaust turbo superchargers are arranged in parallel in an intake passage, and a switching control of the plurality of exhaust turbo superchargers is performed corresponding to an area preset according to an engine load. In a control device for a turbocharged engine, a full exhaust turbocharger is operated from a state where a part of the plurality of exhaust turbochargers is operating in a region corresponding to a first engine speed. In the region corresponding to the first switching unit for switching and the second engine rotational speed equal to or lower than the first engine rotational speed, the exhaust gas turbocharger is operated by the switching by the first switching unit. A second switching means for switching from a state in which a plurality of exhaust turbochargers are operated to a state in which a part of the plurality of exhaust turbochargers is operated, and a state in which all exhaust turbochargers are operated by the first switching means. When a region corresponding to the engine speed between the first engine speed and the second engine speed is reached, a part of the plurality of exhaust turbochargers is activated after a predetermined time. A control device for an engine with a supercharger, comprising: a third switching means for switching. 2. The control device for the engine with a supercharger according to claim 1, wherein the switching by the third switching means after a predetermined time is performed when the engine load is equal to or lower than a predetermined value.