JP2772809B2 - Control device for supercharged engine - Google Patents

Description

The present invention relates to a control device for a supercharged engine in which a plurality of superchargers are arranged in parallel.

(Prior Art) Conventionally, as described in Japanese Utility Model Laid-Open No. 60-178329 and Japanese Patent Laid-Open No. 60-259722, two primary turbochargers and a secondary turbocharger are provided in An exhaust cut valve and an intake cut valve are respectively provided on the turbine inlet side and the blower outlet side of the turbocharger on the side, and these cut valves are opened and closed, so that the turbocharger on the primary side in the low flow rate region of the intake air amount. There is known an engine called a twin turbo type or a sequential turbo type in which supercharging is performed only by a turbocharger and a secondary turbocharger is operated in a high flow rate region.

By the way, in such a sequential turbo, the switching condition for switching the secondary turbocharger from the inactive state to the active state or vice versa from the inactive state to the inactive state is such that the torque shock at the time of switching becomes small. In general, the intake air amount line is set such that there is no large difference in the supercharging pressure before and after the switching. However, when the switching condition is set only by such an equal intake air amount line, in a region where the engine load is high, the variation of the switching timing becomes large, and the torque fluctuation at the time of switching cannot be reduced reliably. There is a problem. This is due in part to the detection accuracy of the air flow meter that detects the amount of intake air,
Another problem is the characteristic of the amount of intake air. That is, as shown in FIG. 1, a normal air flow meter has the characteristic that the output voltage is saturated on the high intake air amount side, but the switching line of the sequential turbo corresponds to the point where this voltage is saturated. The accuracy of the detection of the switching point set in the substantially equal intake air amount line may be originally not very good, and as shown in FIG. 2, as a characteristic of the sequential turbo, the engine speed near the switching point However, the change in the intake air amount is small even when the intake air amount rises, which makes it more difficult to accurately detect the switching point based on the intake air amount. Moreover, the equal intake air amount line itself to be a switching point has a large variation due to a characteristic error of the primary-side supercharger, and the influence of this variation is particularly remarkable at a higher load. Therefore, if the switching line is simply set based on the intake air amount, the switching in the high load region is uncertain and the torque shock may not be prevented.

(Object of the Invention) The present invention has been made in view of the above problems,
An object of the present invention is to provide a control device for a sequential turbocharger that can reliably switch between operation and non-operation of a high flow rate supercharger particularly in a high engine load region and prevent torque shock.

(Constitution of the Invention) In the present invention, the switching condition in the sequential turbo is set based on the equal intake air amount, and on the high load side, the setting of the switching condition is set such that the element of the engine speed that can be reliably detected is large. Thus, the reliability of the switching is increased, and the configuration is as follows. That is, the control device for the supercharged engine according to the present invention includes the first supercharger, which operates at least on the low flow rate side of the intake air flow, and the second supercharger, which operates on the high flow rate side with the turbine. In a supercharged engine having a blower and a turbine arranged in parallel in an intake passage and an exhaust passage, respectively, the second supercharger is switched from a non-operating state to an operating state and from the operating state to the non-operating state. The switching is performed based on the equal intake air amount defined by the engine speed and the engine load, and is performed under a switching condition in which the element of the engine speed is set to be larger on the high load side.

The switching condition in the high load region may be set based on the engine speed.

Further, a switching condition may be set such that switching is performed at a predetermined engine speed in a high load region equal to or higher than a predetermined load, and is performed at a lower load as the rotation speed increases below a predetermined load.

Further, the control device of the supercharged engine according to the present invention,
An engine with a supercharger in which a first turbocharger of an exhaust turbo type operating at least in a low flow rate region of an intake air amount and a second turbocharger of an exhaust turbo type operating in a high flow rate region are arranged in parallel A first exhaust passage in which a turbine of the first supercharger is provided, a second exhaust passage in which a turbine of the second supercharger is provided, and a second exhaust passage. An exhaust cut valve for opening and closing an exhaust passage, a first intake passage in which a blower of the first supercharger is provided, and a second intake passage in which a blower of the second supercharger is provided An intake cutoff valve that opens and closes the second intake passage downstream of the blower of the second supercharger; an operating state detecting unit that detects an operating state of the engine; Opening the exhaust cut valve and the intake cut valve in the high flow rate region, Switching control means for switching the turbocharger from an inoperative state to an operating state; and a predetermined engine speed at a predetermined load or more, and a high engine speed at a predetermined load or less at a low load side from the inactive state at a lower load side. Switching line setting means for setting a switching line for operating the switching control means so as to switch to the operating state may be provided.

The switching line means is preferably managed by a control map.

(Operation) The first supercharger operates at least when the engine is in a low flow rate region, and the second supercharger operates when the engine is in a high flow rate region. The switching from the inoperative state to the operating state and the switching from the operating state to the inoperative state of the second supercharger are performed based on the intake air amount such that the torque change due to the switching is small. This is performed according to the switching condition set so that the factor of the engine speed becomes large.

(Example) Hereinafter, an example is described based on drawings.

 FIG. 3 is an overall system diagram of one 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 of each other for each cylinder. The turbine 105 of the primary turbocharger 104 is disposed in one of the two exhaust passages 202 and 203, and the turbine 107 of the secondary turbocharger 106 is disposed in the other.
The two exhaust passages 102 and 103 merge into a single stream downstream of the turbines 105 and 107 and are connected to a silencer (not shown). The intake passage 109 is divided into two parts downstream of an air cleaner (not shown), and a blower 111 of the primary turbocharger 104 is provided in the middle of the first branch passage 110.
A blower 113 of the secondary turbocharger 106 is provided in the middle of the branch passage 112. These branch passages 110, 112
Are formed so as to face each other at the branch portion and extend substantially straight on both sides. In addition, two branch passages 110, 11
2 merges again downstream of each blower 111,113. Then, an intercooler 114 is disposed in the intake passage 109 that 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. Has been established. 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 passages 117, 11
8 are provided with fuel injection valves 119 and 120, respectively.

An air flow meter 121 that detects the amount of intake air is provided upstream of the intake passage 109 at a position upstream of a branch portion of the first and second branch passages 110 and 112.

The two exhaust passages 102 and 103 are connected to each other by a relatively small-diameter communication passage 122 upstream of both the primary and secondary turbochargers 104 and 105. The exhaust passage 1 in which the secondary turbine 107 is disposed
In 03, an exhaust cut valve 123 is provided immediately downstream of the opening position of the communication passage 122. Further, a bypass passage 125 extending from the middle of the communication passage 122 and communicating with a combined exhaust passage 124 downstream of the turbines 105 and 107 is formed, and the bypass passage 125 has a waste gate valve 127 linked and connected to a diaphragm type actuator 126. Are arranged. Further, a leakage passage 128 is formed for communicating the upstream portion of the waste gate valve 127 of the bypass passage 125 and the exhaust cut valve 123 downstream of the exhaust passage 103 connected to the secondary turbine 107, and the diaphragm passage 128 An exhaust leak valve 130 linked to the actuator 129 is provided.

The exhaust cut valve 123 is a diaphragm type actuator 1
It is linked to 31. On the other hand, an intake cut valve 132 is provided downstream of the blower 113 in the branch passage 112 where the blower 113 of the secondary turbocharger 106 is provided. The intake cut valve 132 is constituted by a butterfly valve, and is also linked to a diaphragm type actuator 133. A relief passage 134 is formed in the branch passage 112 on the secondary side so as to bypass the blower 113, and a diaphragm-type intake relief valve 135 is disposed in the relief passage 134.

The pressure chamber of the actuator 129 that operates the exhaust leak valve 130 is connected to the primary turbocharger 1 via a conduit 136.
The blower 111 is connected to the downstream side of the blower 111 of the branch passage 110 in which the blower 111 is disposed. When the pressure downstream of the blower 111 becomes equal to or higher than a predetermined value, the actuator 129 is operated to open the exhaust leak valve 130, thereby the exhaust cut valve 1
A small amount of exhaust gas passes through bypass passage 12 when 23 is closed.
8 and is supplied to the turbine 107 on the secondary side. Therefore, secondary turbocharger 106 starts rotating before exhaust cut valve 123 opens. During this time, the air relief valve 135 is opened as described below,
The rotation of the secondary turbocharger 106 is increased, the transient response when the exhaust cut valve 123 is opened is improved, and the torque shock is reduced.

The pressure chamber of the actuator 133 for operating the intake cut valve 132 is connected by a conduit 137 to the output port of an electromagnetic solenoid type three-way valve 138. Also, the exhaust cut valve 123
Is connected to the output port of another three-way valve 140 of the electromagnetic solenoid type via a conduit 139. Further, the pressure chamber of the actuator 141 that operates the intake relief valve 135 is connected to an output port of another three-way valve 143 of an electromagnetic solenoid type by a conduit 142.
The intake relief valve 135 is connected to the exhaust cut valve 123 as described later.
The relief passage 134 is kept open until a predetermined time before the intake cut valve 132 is opened. Thus, when the secondary turbocharger 106 is pre-rotated by the exhaust gas flowing through the leak passage 128, the pressure upstream of the intake cut valve 132 is suppressed from rising and entering the surging region. Increase rotation.

The actuator 1 for operating the wastegate valve 127
26 is another three-way valve 145 of the electromagnetic solenoid type by a conduit 144
Connected to the output port.

The above four electromagnetic solenoid type three-way valves 138,140,143,145
Is controlled by a control unit 146 configured using a microcomputer. To the control unit 146, in addition to the engine speed R and the intake air amount Q, the throttle opening TVO, the supercharging pressure P1 downstream of the primary-side blower 111, and the like are input, and based on these, the following control 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 input port is connected to a differential pressure detection valve described later via a conduit 149. It is connected to 150 output ports 170. The intake negative pressure downstream of the throttle valve 116 is introduced into the negative pressure tank 148 via a check valve 151. 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 connected to the conduit 15.
2, the conduit 14 connected to the negative pressure tank 148.
Connected to 7. On the other hand, one input 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 input port is open to the atmosphere. 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 blower 111 on the primary side by a conduit 154. Have been.

As shown in FIG. 4, the casing 161 of the differential pressure detecting valve 150 has first and second two diaphragms 1.
It is divided into three chambers 164,165,166 by 62,163. A first input port 167 is opened in the first chamber 164 on one end side, and a compression spring 168 is disposed between the inner surface of the end of the casing 161 and the first diaphragm 162. . Further, a second input port 169 is opened in the middle second chamber 165, and a third chamber 166 on the other end side is opened.
An output port 170 is opened at the center of the end wall of the casing 161 and an atmosphere release port 171 is opened at the side wall. And
The first diaphragm 162 is fixedly provided with a valve element 172 that penetrates through the second diaphragm 163 and extends toward the output port 170 of the third chamber 166.

As shown in FIG. 3, the first input port 167 is connected to the downstream side of the intake cut valve 132 by a conduit 173, and the supercharging pressure P1 downstream of the primary side blower 111 is supplied to the first chamber 164.
To be introduced. Also, the second input port 169 is connected by a conduit 174 upstream of the intake cut valve 132, thus
The pressure P2 on the upstream side of the intake cut valve 132 when the intake cut valve 132 is closed is introduced. When the difference between the pressures P1 and P2 introduced from the two input ports 167 and 169 is equal to or greater than a predetermined value, the valve element 172 opens the output port 170. 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, in a state where 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 conduit 149 connected to the output port of the differential pressure detection valve 150, the differential pressure P2-P1 Becomes larger than a predetermined value,
Air is introduced into the actuator 133, and the intake cut valve 132 is opened. Also, the three-way valve 138 is
When the conduit 137 on the third side is communicated with the conduit 147 connected to the negative pressure tank 148, a negative pressure is supplied to the actuator 133, and the intake cut valve 132 is closed.

On the other hand, the exhaust cut valve 123 has a three-way valve 140 for controlling the exhaust cut valve 123 and an actuator 131 for operating the exhaust cut valve 123.
When the conduit 139 leading to the pressure chamber is connected to the conduit 152 on the negative pressure tank 148 side, the actuator 131 is closed by supplying a negative pressure. Also, the three-way valve 140
When the exhaust gas releases the conduit 139 to the atmosphere, the exhaust cut valve 123 is opened, and supercharging is performed by the secondary turbocharger 106.

FIG. 5 shows the open / close state of the intake cut valve 132, the exhaust cut valve 123, the intake relief valve 135, and the wastegate valve 127,
6 is a control map shown together with the open / close state of an exhaust gas leak valve 130. This map is stored in the control unit 146, and based on this map, the above-mentioned four electromagnetic solenoid type three-way valves 138, 140, 143, 145 are controlled.

In this control map, a line that defines the opening and closing conditions of each of the intake relief valve 135, the exhaust cut valve 123, and the intake cut valve 132 is based on an equal intake air amount line, which is determined by the engine speed on the high load side. It is set to a cut shape.

In a region where the engine speed R is low or the intake air amount Q is small, the intake relief 135 is open, and the secondary leakage of the secondary turbocharger 106 is performed by opening the exhaust leakage valve 130. Then, when the engine speed reaches R2 or the intake air amount reaches the line of Q2, the intake relief valve 135 is closed, and thereafter, the pressure downstream of the secondary-side blower 113 increases until the exhaust cut valve 123 opens. When the exhaust gas reaches the line Q4-R4, the exhaust cut valve 123 opens, and then, when the exhaust cut valve 123 reaches the Q6-R6 line and the intake cut valve 132 opens, supercharging by the secondary turbocharger 106 starts, and this Q6-R6 Enter the supercharging region with both primary and secondary turbochargers at the line.

The intake cut valve 132, the exhaust cut valve 123, and the intake relief valve 135 have some hysteresis from the high flow side to the low flow side, that is, Q5-R5, Q shown by a broken line in FIG.
It switches on each line of 3-R3 and Q1-R1.

The broken portions of these lines are on a 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 equal to or higher than a predetermined value, and the supercharging pressure P1 downstream of the primary blower is equal to or higher than a predetermined value.

The Q1 to Q6 and R1 to R6 in this control map are set as shown in FIG.
The values of Q3 to Q6 and R3 to R6, which define the opening and closing timing of the intake cut valve 132 and the opening and closing timing of the intake cut valve 132, are set such that Q3 to Q6 are increased in the lower gear, and R3 to R6 are increased in the lower gear. this is,
The low-speed gears, especially at the first gear, have a fast boost during acceleration, while the high-speed gears have a slow start-up. Is set to the optimal value of.

FIGS. 7 and 8 are flowcharts for executing the above control of the intake cut valve 123, the exhaust cut valve 132, and the intake relief valve 135 in this embodiment. S indicates each step. Also, F is a flag, and the meaning of this flag state (F = 1 to 6) is as shown in FIG. 5, and the previous transition respectively corresponds to the high level of the Q1-R1 line. The transition from the flow side to the low flow side (F = 1), the transition from the low flow side to the high flow side of the Q2-R2 line (F = 2), the low flow from the high flow side of the Q3-R3 line The transition to the flow side (F = 3), the transition from the low flow side to the high flow side of the Q4-R4 line (F = 4), Q5-R5
The transition from the high flow side to the low flow side of the line (F =
5) This corresponds to each state of the transition from the low flow rate side to the high flow rate side of the Q6-R6 line (F = 6). Hereinafter, description will be made step by step.

First, in FIG. 7, the process is started, and initialization (initialization) is performed in S1. At this time, the flag is set to 1.

Next, at S2, the intake air amount Q, the engine speed R, and the gear stage G are input. Then, in S3, map values Q1 to Q6 and R1 to R6 for each gear are read. Then, go to S4.

In S4, it is checked whether or not the flag F is 1, that is, whether or not the previous transition is from the high flow side to the low flow side of the Q1-R1 line. Note that initially F = 1, so this determination is YES.

Then, if F = 1, the process goes to S5 to determine whether or not the current Q is larger than Q2. If YES, then it is determined whether or not the current R is larger than R2 in S6. If YES in S5 and S6, the process proceeds to S7, where the flag F is set to 2, and in S8, control is performed to close the intake relief valve (atmospheric pressure is introduced into the actuator). If the determination in S5 or S6 is NO, the process returns.

If the determination in S4 is NO, the process proceeds to S9 and the flag F
Is an even number, that is, whether the previous transition has occurred on any line from the low flow rate side to the high flow rate side.

If YES in S9, the process goes to S10 and determines whether or not F = 2, that is, whether or not the previous shift was from the low flow rate side to the high flow rate side of the Q2-R2 line. If so, go to S11.

In S11, it is determined whether Q is greater than Q4 this time, and N
If it is O, then it is checked in S12 whether or not this time R is larger than R4. When YES is determined in both S11 and S12, the process proceeds to S13, where the flag F is set to 4, and in S14, control is performed to open the exhaust cut valve (a negative pressure is introduced into the actuator).

If the determination in S11 or S12 is NO, the process goes to S15 to check whether Q is smaller than Q1 this time.

If NO in S15, it is checked in S16 whether R is smaller than R1 this time. If YES in any of S15 and S16, the process proceeds to S17, where the flag F is set to 1, and in S18, control is performed to open the intake relief valve (a negative pressure is introduced into the actuator). If the determinations in S15 and S16 are both NO, the process returns.

If the determination in S10 is NO, the process proceeds to S19 and the flag F is set to 4
That is, it is determined whether the previous transition was a transition from the low flow rate side to the high flow rate side of the Q4-R4 line.

If YES in S19, it is checked in S20 whether this time Q is larger than Q6. If YES, then in S21, it is checked whether R this time is larger than R6. If the determinations in S20 and S21 are both YES, the flow proceeds to S22, where the flag F is set to 6, and in S23, control is performed to open the intake cut valve (the actuator is connected to the differential pressure detection valve side).

If NO in S20 or S21, S24
Then, it is determined whether or not Q is smaller than Q3. If NO, it is determined in S25 whether or not R is smaller than R3. If YES in either S24 or S25, the flow proceeds to S26, where the flag F is set to 3, and in S27, control is performed to close the exhaust cut valve (atmosphere is introduced into the actuator).

If the determination in S19 is NO, F = 6, that is, the previous transition is a transition from the low flow rate side to the high flow rate side of the Q6-R6 line. Q
Is smaller than Q5. If NO, then in S29, it is determined whether R this time is smaller than R5.
If YES in S28 or S29, S30
Then, the flag F is set to 5, and control for closing the intake cut valve is performed in S31 (introducing a negative pressure to the actuator). If the determinations in S28 and S29 are both NO, the process returns.

Next, the flow when the determination in S9 is NO will be described with reference to FIG.

If NO in S9, the process goes to S41 to determine whether or not the flag F is 3, that is, whether or not the previous transition was from the high flow side to the low flow side of the Q3-R3 line. If YES, then it is determined in S42 whether or not the current Q is smaller than Q1, and if NO, it is determined in S43 whether or not R this time is smaller than R1. If YES in either S42 or S43, the process proceeds to S44 to set the flag F to 1, and then controls to open the exhaust cut valve in S45.

If the determinations in S42 and S43 are both NO, go to S46, see if Q is greater than Q4,
At 47 it is determined whether R is greater than R4. And S4
If the determinations in steps 6 and S47 are both YES, the process proceeds to step S48 to set the flag F to 4, and then controls to open the exhaust cut valve in step S49. NO in either S46 or S47
If so, return.

If NO in S41, it means that F = 5. In this case, go to S50 to determine whether Q is smaller than Q3. If NO, determine in S51 whether R is smaller than R3. I do. If YES in either S50 or S51, the flag F is set to 3 in S52, and then control is performed to close the exhaust cut valve in S53.

If the determinations in S50 and S51 are both NO, the process goes to S54 to determine whether Q is greater than Q6, and if YES, then it is determined in S55 whether R is greater than R6.
If the determinations in S54 and S55 are both YES, S
The flow goes to 56 to set the flag F to 6, and then to control to open the intake cut valve in S57.

If NO in either S54 or S55, the process returns.

In the above-described embodiment, the switching line set by the equal intake air amount line is cut off at the engine speed on the high load side so that the switching line rises straight in FIG. Alternatively, the high load side may rise slightly inclining.

(Effects of the Invention) Since the present invention is configured as described above, in a sequential turbo engine, even if there is a variation in the intake air amount line or a detection error due to a characteristic error or the like of the low-flow-side supercharger, the engine may be used. The operation switching of the high-flow-side supercharger in the high-load region can be reliably performed to prevent torque shock.

[Brief description of the drawings]

FIG. 1 is an output characteristic diagram of an air flow meter, FIG. 2 is a characteristic diagram showing a relationship between an engine speed and an intake air amount in a turbocharged engine, and FIG. 3 is an overall system diagram of one embodiment of the present invention. FIG. 4 is a cross-sectional view of the differential pressure detecting valve of the embodiment, FIG. 5 is a control characteristic diagram of the embodiment, and FIG.
Tables showing setting values in the characteristic diagram of FIG.
FIG. 6 is a flowchart for executing the control of the embodiment.
101: engine, 104: primary turbocharger, 106: secondary turbocharger, 123: exhaust cut valve, 132: intake cut valve, 146: control unit.

Claims (5)

(57) [Claims] An intake passage and an exhaust respectively include a blower and a turbine of a first supercharger operated at least on a low flow rate side of an intake air amount and a blower and a turbine of a second supercharger operated on a high flow rate side of an intake air amount. In the supercharged engine arranged in parallel in the passage, switching of the second supercharger from the inoperative state to the operating state and switching from the operating state to the inoperative state are performed by the engine speed and the engine load. A control device for an engine with a supercharger, characterized in that the control is performed under a switching condition in which an element of the engine speed is increased on a high load side based on a prescribed equal intake air amount. 2. The control device for a supercharged engine according to claim 1, wherein the switching condition in a high load region is set based on an engine speed. 3. The supercharger according to claim 1, wherein the switching condition is set such that switching is performed at a predetermined engine speed in a high load region above a predetermined load and at a lower load side as the rotation speed increases below a predetermined load. Engine control device. 4. An exhaust turbo-type first supercharger that operates at least in a low flow rate region of the intake air amount and a second exhaust turbo-type supercharger that operates in a high flow rate range are arranged in parallel. A supercharged engine, comprising: a first exhaust passage in which a turbine of the first supercharger is provided; and a second exhaust passage in which a turbine of the second supercharger is provided. An exhaust cut valve for opening and closing the second exhaust passage; a first intake passage in which a blower of the first supercharger is provided; and a blower of the second supercharger. A second intake passage; an intake cutoff valve for opening and closing the second air passage downstream of the blower of the second supercharger; an operating state detecting means for detecting an operating state of the engine; Receiving the output of the exhaust cut valve and the intake cut in a high flow rate region. Switching control means for switching the second supercharger from a non-operation state to an operation state by opening the second supercharger; a predetermined engine speed at a predetermined load or more; A control device for a supercharged engine, comprising: switching line setting means for setting a switching line for operating the switching control means so as to switch a charging machine from an inoperative state to an operating state. 5. The control device for a supercharged engine according to claim 4, wherein said switching line means is managed by a control map.