JPH02201025A - Control device for engine with supercharger - Google Patents

Abstract

PURPOSE:To improve the accelerationability from the low rotation area in a sequential turbo by providing an exhaust cut valve for opening/closing an exhaust passage in which a turbine of a supercharger to be operated in the high flow quantity side is provided, and controlling that valve to close in the low flow quantity area except the low rotation area. CONSTITUTION:A primary turbo supercharger 104 to be operated in the low flow quantity side of the intake air quantity and a secondary turbo supercharger 106 to be operated in the high blow quantity side are provided in parallel with intake air passages 110, 112 and exhaust passages 102, 103. An exhaust cut valve 123 is provided in the exhaust passage 103 in which a secondary side turbine 107 is located, while an intake cut valve 132 is provided in the downstream side of a secondary side blower 113 of the exhaust passage 112 in which the blower is located. The exhaust cut valve 123 is opened/closed by a diaphragm type actuator 131, and the actuator 131 controls the exhaust cut valve 124 with a three-way valve 140 so as to open in the high flow quantity area and close in the low flow quantity area except for the low rotation area.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a control device for a supercharged engine in which a plurality of turbochargers are arranged in parallel.

(Prior art) Conventionally, Japanese Unexamined Utility Model Publication No. 178329/1983,
As described in Publication No. 259722, an engine is equipped with two turbo superchargers, a primary and a secondary turbo supercharger, and an exhaust cut valve and an exhaust cut valve are installed on the turbine inlet side and blower outlet side of the secondary turbo supercharger. By installing intake cut valves and opening and closing these cut valves, supercharging is performed only by the primary side turbocharger in low flow areas of intake air amount, and supercharging is performed by the secondary side turbocharger in high flow areas. Engines called twin-turbo or sequential turbo engines are known.

By the way, in the case of a sequential turbo, in a low-flow region of engine intake air when the secondary turbocharger is not activated, exhaust gas flows only to the turbine of the primary turbocharger, which increases exhaust resistance. do. Therefore, in the sequential turbo, the exhaust pressure in the low flow rate region becomes higher than in the case of the single turbo.

This increase in exhaust pressure in the low flow rate region causes various problems in terms of engine performance.

In particular, in response to the desire to increase fuel efficiency by squeezing the fuel as much as possible while avoiding deterioration of combustion during idling, when the exhaust pressure is high, it is necessary to deal with deterioration of combustion by increasing the amount of intake air and enriching the fuel. However, deterioration in fuel efficiency is unavoidable. In addition, when accelerating from an idle state or at full throttle from a low-speed steady running state close to the road load line, if the exhaust pressure is high, the exhaust pumping loss will increase and the required fuel amount will increase. A problem arises in that the torque decreases and one-minute acceleration cannot be obtained.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to improve acceleration performance by reducing exhaust pressure in a low rotation range including idling operation in a sequential turbo.

(Structure of the Invention) The present invention provides that when accelerating from an idle state or accelerating at full throttle from near a road, there is a turbo lag in the initial stage until the pressure inside the intake pipe reaches atmospheric pressure, and supercharging is carried out by the engine. Therefore, in a sequential turbo, the exhaust cut valve is opened in the low rotation range corresponding to the initial stage of acceleration, and the exhaust gas is allowed to flow through both turbines. Reduce exhaust pressure and improve torque, and
At the same time, the exhaust cut valve is opened during idling to lower exhaust pressure and improve fuel efficiency. That is, the control device for a supercharged engine according to the present invention has at least a blower and a turbine of a first turbocharger that are operated in a low flow rate region of the intake air amount, and a second turbocharger that is operated in a high flow rate region of the intake air amount. In a supercharged engine in which a blower and a turbine of a charger are arranged in parallel in an intake passage and an exhaust passage, respectively, an exhaust cut valve that opens and closes an exhaust passage in which a second turbine is interposed, and the exhaust cut valve control means that opens the engine in a high flow rate region, opens it in a predetermined low engine speed range including an idling operation range, and closes it in a low flow rate range other than the low speed range.

Here, the low rotation range in which the exhaust cut valve is opened is preferably set to an operating range below a predetermined engine speed and below a predetermined engine load, including an idling operating range.

(Function) The first turbocharger operates in a low flow rate region of the intake air amount, and when the intake air amount reaches a high flow rate region, the exhaust cut valve opens and the second turbocharger operates. In addition, even if the flow rate is low, when the engine is in a predetermined low rotation range including the idle operating range, the exhaust cut valve opens and the exhaust gas is supplied to both the first and second turbocharger turbines. Engine exhaust gases are channeled, thereby reducing exhaust resistance. Therefore, the exhaust pressure at idle is kept low and combustion is stabilized, and the exhaust pressure is kept low at the beginning of acceleration from a low rotation range, improving acceleration performance.

In addition, by setting the predetermined region on the low-speed side where the exhaust cut valve is opened to be below the predetermined engine load, the effect of increasing torque due to initial exhaust pressure reduction when accelerating from the low-speed region is even more reliable. becomes.

(Example) Examples will be described below based on the drawings.

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 202 and 203 are provided independently for each cylinder. A turbine +05 of the primary turbocharger 104 is disposed in one of the two exhaust passages 202 and 203, and a turbine 107 of the secondary turbocharger 106 is disposed in the other. Two exhaust passages 102, 10
3 merge into one line downstream of both turbines 105 and 107, and are connected to a silencer (not shown).

Further, the intake passage 109 is divided into two downstream of an air cleaner (not shown), and the blower II+ of the primary turbo supercharger 104 is located in the middle of the first branch passage 110, and the blower II+ of the primary turbo supercharger 104 is in the middle of the second branch passage 112. Blower II3 of the secondary turbo supercharger 106 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 for each blower II+.

It rejoins downstream of 113. Then, an intercooler 114 is disposed in the intake passage 109, which has become one again, and a surge tank +15 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. In addition, the intake passage 10
The downstream end of 9 branches into two independent intake passages 117 and 118 corresponding to each cylinder of the engine 101, and is connected to each intake boat (not shown). Each of these independent intake passages 117 and 118 has a fuel injection valve ++.
9,120 are arranged.

On the upstream side of the intake passage 109, there is an air flow meter located upstream of the branch of the first and second branch passages 110, 112 to detect the amount of intake air! 21 are provided.

The two exhaust passages 102, 103 are communicated with each other by a relatively small-diameter communication passage 122 upstream of both the primary and secondary turbochargers [1104, 105]. In the exhaust passage I03 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. Further, the turbine 105 extends from the middle of the communication path +22.
A bypass passage 125 is formed which communicates with the combined exhaust passage 124 downstream of 107, and a wastegate valve 127 linked to a diaphragm type actuator 126 is disposed in the bypass passage 125. and,
A leak passage 128 is formed that communicates the upstream part of the waste gate valve 127 in the bypass passage 125 with the downstream part of the exhaust cut valve 123 in the exhaust passage 103 connected to the secondary turbine 107. An exhaust leak valve 130 is provided which is linked to the exhaust leak valve 130 .

The exhaust cut valve 123 is linked to a diaphragm type actuator 131. On the other hand, the branch passage + where the blower 113 of the secondary turbocharger 106 is disposed
12, an intake cut valve 132 is disposed downstream of the blower 11. This intake cut valve 132 is composed of a butterfly valve, and is also driven by a diaphragm type actuator 13.
Linked to 3. Further, a relief passage 134 is formed in the branch passage 112 on the secondary side so as to bypass the blower 113.
4 is provided with a diaphragm type intake relief valve 135.

The actuator 12 that operates the exhaust leak valve 130
The pressure chamber 9 is connected via a conduit I36 to a branch passage 11 in which a blower I11 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 leak into the bypass passage summer 28 when the exhaust cut valve 123 is closed. and is supplied to the secondary turbine 107. Therefore, the secondary turbo supercharger 106 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 by a conduit 137 to the output port of the electromagnetic solenoid type three-way valve 13H. 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 boat. Furthermore, the pressure chamber of the actuator 141 that operates the intake relief valve 135 is
Another electromagnetic solenoid type three-way valve 143 is connected to the conduit +42.
connected to the output port of the Intake relief valve 135
As will be described later, the relief passage +3 is closed until a predetermined time before the exhaust cut valve I23 and the intake cut valve 132 open.
Leave 4 open. As a result, the leak passage 12
The exhaust gas flowing through the secondary turbo supercharger 1
During pre-rotation of the valve 06, the pressure upstream of the intake cut valve +32 rises to prevent it from entering the surging region, and also increases the rotation of the proar 113.

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 above four electromagnetic solenoid type three-way valves 138, 140.1
43 and 145 are controlled by a control unit I46 configured using a microcomputer. The control unit 146 has an engine speed R9.
Inhaled air! ! In addition to Q, throttle opening TVO, primary side blower 11! The downstream supercharging pressure Pl and the like are inputted, and based on them, the control 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 the negative pressure tank 148 via a conduit 147, and the other input port is connected to the conduit W1.
Output port of the differential pressure detection valve +50 (described later) via 49! 7
Connected to 0.

Intake negative pressure downstream of the throttle valve +16 is introduced into the negative pressure tank 148 via a check valve 151. Further, one input boat of the three-way valve 140 for controlling the exhaust cut valve is open to the atmosphere, and the other input boat 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 input port of the intake relief valve 135@common three-way valve 143 is connected to the negative pressure tank 148, and the other input port is open to the atmosphere. In addition, waste gate valve 127
One input port of the three-way control valve 145 is open to the atmosphere, and the other input port is a conduit! 54, it is connected to the conduit 136 that communicates with the downstream side of the primary blower III.

As shown in FIG. 2, the differential pressure detecting valve 150 has three chambers 164, 165, 165, 165, 165, 165, 162, 162, 363, 362, 363, 363, 363, 363, 363, 362, 363, 363, 363, 40, 363. J
It is divided into 66 sections. A first input boat [67] is opened in the first chamber 164 on one end side, and the inner surface of the end portion of the casing 16I and the first diaphragm 16
A compression spring 1611t is disposed between the two. In addition, in the second room 165 in the middle, there is a second human-powered boat.
69 is opened, and in the third chamber 166 on the other end side, an output port 170 is opened at the center of the end wall of the casing 181, and an atmosphere release boat 171 is opened at the side wall. The first diaphragm 162 has the output port 170 of the third chamber 166 passing through the second diaphragm 163.
A valve body 172 extending toward is fixedly provided.

The first input boat +67 is connected by conduit 173 to the first
As shown in the figure, it is connected to the F flow side of the intake cut valve 132, and introduces the supercharging pressure P1 downstream of the primary side blower 111 into the first chamber 164.

The second input boat 169 is also connected upstream of the intake cut valve 132 by conduit +74, and thus the intake cut valve 132 when the intake cut valve +32 is closed.
The upstream pressure P2 is introduced. The pressures PI, P introduced from this two-man powered boat 167.169
If the difference between 2 is greater than a predetermined value, the valve body! 72 opens output port 170. This output port 170 is connected via conduit 149 to one of the three-way valves 138 for controlling the intake cut valve 132. Therefore, the three-way valve 138 connects the conduit 137 connected to the pressure chamber of the actuator 133 for operating the intake cut valve 132 to the differential pressure detection valve 15.
When the differential pressure P2-PI becomes larger than a predetermined value while communicating with the conduit 149 connected to the output port 0, the atmosphere is introduced into the actuator +33 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 negative pressure tank +4
When connected to the conduit 147 connected to the actuator +33, negative pressure is supplied to the actuator +33, and the intake cut valve +3
2 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. Further, when the three-way valve 14.0 releases the conduit 139 on the output side to the atmosphere, the exhaust cut valve 123 is opened and supercharging is performed by the secondary turbo supercharger +06.

FIG. 3 shows the intake cut valve 132. exhaust cut valve 123,
It is a control map showing the opening and closing states of the intake relief valve 135 and the waste gate valve 127, as well as the opening and closing state of the exhaust leak valve 130. This map is stored in the control unit 146, and based on this map, the above 4I
I electromagnetic solenoid type three-way valve 138, 140, 143,
145 control is performed.

In a region where the engine speed R is low or the intake air amount Q is small, the intake relief [35 is open, and the secondary turbocharger 106 is pre-rotated by opening the exhaust leakage valve 130. When the engine speed reaches R2 or the intake air amount reaches Q2, the intake relief valve 135 is closed, and the pressure downstream of the secondary blower 113 increases until the exhaust cut valve 123 opens. When the line Q4-R4 is reached, the exhaust cut valve 123 opens, and then the Q4-R4 line is reached.
When the 6-R6 line is reached and the intake cut valve +32 is opened, supercharging by the secondary turbo supercharger +06 begins, and the supercharging region by both the primary and secondary superchargers begins at the Q6-R6 line.

Intake cut valve 132. The exhaust cut valve 123 and the intake relief valve 135 have a slight hysteresis from the high flow rate side to the low flow rate side, that is, the Q shown by the broken line in FIG.
It is switched on each line of 5-R5, Q3-R3, and Q14+.

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 PI downstream of the primary side blower is greater than or equal to a predetermined value.

In addition, at a predetermined Po
In the shaded area in FIG. 3 where the exhaust gas does not reach the target temperature, the exhaust cut valve 123 and the intake cut valve 132 are opened, the intake relief valve 135 is closed, and the secondary turbo supercharger is operated.

FIG. 4 shows a region (P) in which only the primary turbocharger 104 operates and a region (P+S) in which the secondary turbocharger 106 operates in addition to the primary turbocharger 104 in this embodiment at different engine speeds. FIG.

Further, FIG. 5 shows changes in the throttle opening degree and the pressure in the intake pipe during full-throttle acceleration from a low rotation range. As shown in Fig. 5, at the moment when the accelerator is depressed when fully accelerating from a low rotation range, the pressure inside the intake pipe is atmospheric pressure (P =
It only rises to 0). Then, supercharging gradually takes effect. Therefore, in this embodiment, this intake pipe internal pressure is a predetermined value P. In the above region up to the point where the torque is reached, the exhaust pressure is lowered by flowing the exhaust gas to the secondary turbine to prevent the torque from becoming low.

6 and 7 show the intake cut valve 123 in this embodiment. Exhaust cut valve! 32 and intake relief valve!
35 is a flowchart for executing the above control of No. 35. Note that S indicates each step.

Further, F is a flag, and the state of this flag (F-i
The meanings of ~6) are as shown in FIG. 3, where the previous transition was a transition from the high flow rate side to the low flow rate side of the Ql-R1 line (F = 1), respectively.
This is the transition from the low flow rate side to the high flow rate side in the Q2-R2 line (F=2), the transition from the high flow rate side to the low flow rate side in the Q3R3 line (F=3), and the low flow rate in the Q4-R4 line. Transition from flow rate side to high flow rate side (F=4), Q5-R5
This is the transition from the high-flow side to the low-flow side of the line (F=5
), which is a transition from the low flow rate side to the high flow rate side of the Q6-R6 line (F=6). below,
Explain step by step.

First, in FIG. 6, the system starts and initialization is performed at Sl. At this time, the flag is set to 1.

Next, in S2, the intake air amount Q, engine speed R, and intake pipe internal pressure P are input. Then, in S3, the map value Ql-
Q6, R1-R6, and P. and read out Ro.

Next, in S4, the intake pipe internal pressure P becomes P. Determine whether the engine speed Rh<
Determine whether it is smaller than R0.

If YES, go to S6 to control the opening of the exhaust cut valve and introduce negative pressure into the actuator).
Control the intake cut valve to open and connect the actuator to the differential pressure detection valve side), close the intake relief valve'/f
ll (Perform IJ (introduce atmospheric pressure to the actuator).

Further, if NO in S4 or NO in S5, the process goes to S7.

In S7, flag F7! Check whether l<+, that is, whether the previous transition was from the high flow rate side to the low flow rate side of the Qf-Rf line. Note that initially F=
1, and therefore, this determination is YES.

If F=1, then go to S8 to determine whether Q is larger than 02 this time, and if No,
Next, in S9, it is checked whether this time R,6<R2. If YES in S8 or YES in S9, go to SIO, set flag F to 2, and
Controls closing of the intake relief valve. Further, if the determinations in S8 and S9 are both No, the process returns directly.

If the determination in S7 is No, go to S12 and check whether the flag F is an even number, that is, the previous transition was a low flow! See if there was a transition in any of the lines from side to island style Il steel.

Then, if YES in S12, go to Sl3 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 S14.

In S+4, it is determined whether this time QIJ is greater than Q4, and if NO, then in S15 it is determined whether this time R is greater than R4. Then, S14 or Sl
If any one of 5 is YES, the process goes to S16 and the flag F is set to 4, and the control to open the exhaust cut valve is performed in S17.

Further, if both of the determinations in S14 and S15 are NO, the process goes to 818 to check whether Q is smaller than Ql this time.

If YES in S18, it is checked in S19 whether Rh<R1 is smaller this time. And if YES, S
20, the flag F is set to I, and the intake relief valve is controlled to open (introducing negative pressure to the actuator) in S21. Also, the judgments of S+8 and S19 are both N.
If it is O, return as is.

If the determination in S13 is NO, go to S22 and check whether the flag F is 4, that is, if the previous transition was 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 522, it is checked in S23 whether Q is larger than Q6 this time, and if it is No, then it is checked in S24 whether R is larger than R6 this time. And S2
If YES in either 3 or S24, S25
, and sets the flag F to 6, and controls the opening of the intake cut valve in S26.

Also, if No in S24, go to S27 and Q is Q3.
Determine whether it is smaller than the
It is determined whether R is smaller than R3. And S
If YES in 28, go to S29 and set flag F to 3, and control to close the exhaust cut valve in S30 (
(introduces atmosphere into the actuator).

If the determination in S22 is NO, it means that F=6, that is, the previous transition was from the low flow rate side to the high flow rate side of the Q6-R6 line, and in this case, go to S31 and change the current flow rate. It is determined whether Q is smaller than Q5, and if YES, then in S32 it is determined whether R is smaller than R5 this time. If YES, go to S33, set flag F to 5, and control to close the intake cut valve (introduce negative pressure to the actuator) in S34.
. Further, if the answer is No in either S31 or S32, the process directly returns.

Next, the flow when the determination in S12 is NO will be explained with reference to FIG.

If NO in S12, 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 Q this time in S42.
Determine whether is smaller than Ql, and if YES,
In S43, it is determined whether R is smaller than R1 this time.

If YES, go to S44 and set flag F to 1.
, and then controls the exhaust cut valve to open at 54.5.

If No in either S42 or S43, S4
6, it is checked whether Q is greater than Q4, and if NO, it is determined in S47 whether R is greater than R4. Then, select YES in either S46 or S47.
If so, go to 548 and set flag F to 4, and then control to open the exhaust cut valve in S49. Also, S
If the answer is No at 47, the process returns directly.

If NO at S41, it means F-5, and in this case go to S50 and Q7! It is determined whether l<Q3, and if YES, it is determined in S51 whether R is smaller than R3. If YES in S51, flag F is set to 3 in S52, and then in S5
3 controls the exhaust cut valve to close.

If No in either S50 or S51, S5
Go to 4 and determine whether Qh (is larger than Q6, N
If it is O, then it is checked in S55 whether R is greater than R6. If YES in either S54 or S55, the process goes to 856 and flag F is set 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.

(Effects of the Invention) Since the present invention is configured as described above, in a sequential turbo engine, exhaust pressure in the low rotation range including idling is reduced, and when accelerating from the low rotation range, the exhaust pressure is reduced. torque and also improves combustibility during idling to improve fuel efficiency.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram of an embodiment of the present invention, FIG. 2 is a sectional view of a differential pressure detection valve in the embodiment, and FIGS. 3, 4, and 5 are characteristic diagrams of the embodiment. FIGS. 6 and 7 are flowcharts for executing control in the same embodiment. 101: Engine, 104 niblimari turbo supercharger,
106: Secondary turbo supercharger, 123: Exhaust cut valve, 146: Control unit.

Claims (2)

[Claims] (1) At least the blower and turbine of the first turbocharger that operates in a low flow rate region of the intake air amount and the blower and turbine of the second turbocharger that operates in a high flow rate region are connected to the intake passage and exhaust, respectively. In a supercharged engine arranged in parallel with a passage, an exhaust cut valve opens and closes the exhaust passage in which the second turbine is interposed, and the exhaust cut valve is opened in the high flow region and in an idle operation region. 1. A control device for a supercharged engine, comprising: a control means that opens in a predetermined engine low rotation range and closes in the low flow rate area excluding the low rotation rotation range. (2) The supercharged engine according to claim 1, wherein the low rotation range in which the exhaust cut valve is opened is set to an operating range below a predetermined engine speed including an idling operating range and below a predetermined engine load. control device.