JP2607624Y2 - Intake device for supercharged engine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for a supercharged engine for a vehicle having a plurality of turbochargers, and more particularly, to an intake system for an intake pipe from a plurality of turbochargers and an intercooler. Regarding the connection part.

[0002]

2. Description of the Related Art In an engine with a supercharger, the air temperature rises when air is sucked and compressed by a turbocharger. Therefore, the compressed air is cooled by an intercooler, and the air density is increased and supplied to the engine. This substantially improves the charging efficiency of the engine. Further, as shown in Japanese Patent Application Laid-Open No. 2-42126, a primary turbocharger and a secondary turbocharger are arranged in parallel in the intake and exhaust systems of an engine, and the intake and exhaust systems connected to the secondary turbocharger are arranged. In the exhaust system, an intake control valve and an exhaust control valve are provided, respectively. When the engine operating range is in a low speed range, both control valves are closed and only the primary turbocharger is supercharged. 2. Description of the Related Art An engine with a supercharger that sometimes improves output performance from a low-speed range to a high-speed range by opening both control valves together and supercharging both turbochargers is known.

[0003] The primary turbocharger is always
Since the supercharging operation is performed and the secondary turbocharger performs the supercharging operation only in the high-speed range, the turbo capacities of the two turbochargers may be made different to be set to a low-speed type and a high-speed type.

[0004]

However, when the turbo capacities of the turbochargers are made different, the inlet areas of the intercoolers to which the intake pipes from the turbochargers are connected are the same or equal to each other. If the relationship is reversed, the compressed air that joins from the turbochargers via the intake pipe through the intercooler during the supercharging operation of both turbochargers causes pressure fluctuations, increasing the intake resistance and increasing the intake efficiency. Disadvantages.

The present invention has been made in view of the above circumstances, and allows compressed air from a plurality of turbochargers to flow smoothly into an intercooler to improve intake efficiency and output performance. It is an object of the present invention to provide an intake device for a supercharged engine.

[0006]

To achieve To achieve the object described above, intake system for an engine with a supercharger according to the present invention is disposed a plurality of turbocharger near the engine body, each of these turbochargers In the intake device of a supercharged engine, each blower discharge side is connected to an inlet side of an intercooler via an intake pipe, and an outlet side of the intercooler is connected to an engine body via a throttle body and an intake manifold. The inlet area ratio of the intercooler to which each intake pipe from the supercharger is connected is set in proportion to the turbo capacity ratio of the turbocharger to which each intake pipe is connected.

[0007]

In the present invention having the above structure, when a plurality of turbochargers are operated together, all of these compressed airs flow into the intercooler and are collected into one, and are cooled to have a large air density. The compressed air is fed to the engine body side and supercharged so as to obtain high filling efficiency.
And even when the turbo capacities of a plurality of turbochargers are different, each inlet area of the intercooler to which each intake pipe from the plurality of turbochargers is connected is set according to the magnitude relationship of the turbo capacities. Thus, any of the compressed air from the plurality of turbochargers smoothly flows into the intercooler without causing pressure fluctuation, and therefore, the intake efficiency of the entire intake system including the plurality of turbochargers is improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. First, referring to FIG. 1, an overall configuration of a supercharged engine to which the present invention is applied will be described. Reference numeral 1 denotes an engine body of a horizontally opposed engine (a four-cylinder engine in this embodiment), and a combustion chamber 5, an intake port 6, an exhaust port 7, and a spark plug 8 are provided in left and right banks 3, 4 of a crankcase 2. , A valve train 9 and the like. The left bank 3 has # 2 and # 4 cylinders, and the right bank 4 has # 1 and # 3 cylinders. Due to this engine shortening shape, a primary turbocharger 40 and a secondary turbocharger 50 are respectively provided immediately after the left and right banks 3 and 4. As an exhaust system, a common exhaust pipe 10 from the left and right banks 3 and 4 is used as a turbine 4 of both turbochargers 40 and 50.
The exhaust pipes 11 from the turbines 40a and 50a join one exhaust pipe 12 and communicate with the catalytic converter 13 and the muffler 14. The primary turbocharger 40 is a small-capacity low-speed type having a large supercharging capacity in a low-to-medium-speed region, and the secondary turbocharger 50 is a large-capacity high-speed type having a large supercharging capability in a medium-to-high-speed region.

[0009] As an intake system, intake pipes 17a and 17b branched into two from an intake pipe 16 connected to an air cleaner 15.
Are blowers 40b of both turbochargers 40 and 50, respectively.
The primary-side and secondary-side intake pipes 18 and 19 from the blowers 40b and 50b are connected to the intercooler 20. The air is communicated from the intercooler 20 to a chamber 22 via a throttle body 27 having a throttle valve 21, and is communicated from the chamber 22 to each cylinder of the left and right banks 3 and 4 via an intake manifold 23. As an idle control system, an idle control valve (ISCV) is provided in a bypass passage 24 between the intake pipe 16 and the intake manifold 23 immediately downstream of the air cleaner 15.
25 and a check valve 26 which is opened by a negative pressure are provided so as to control the amount of intake air during idling or deceleration.

[0010] As a fuel system, injectors 30 are respectively provided at the intake ports 6 of the respective cylinders. A fuel passage 33 from the fuel pump 31 of the fuel tank 32 is connected to the fuel tank 32 via the filter 34, the injector 30, and the fuel pressure regulator 35 so as to return to the fuel tank 32. The fuel pressure regulator 35 adjusts the pressure in accordance with the intake pressure of the intake manifold 23, keeps the fuel pressure of the injector 30 constantly constant with respect to the intake pressure, and controls the fuel injection by the pulse width of the injection signal. It is possible. As an ignition system, the ignition system is connected so that an ignition signal from the igniter 36 is input to an ignition coil 8a connected to each ignition plug 8 of each cylinder.

An operation system of the primary turbocharger 40 will be described. The primary turbocharger 40 uses a blower 40b by the energy of exhaust gas introduced into the turbine 40a.
, And operates so that air is inhaled, pressurized and constantly supercharged. A primary wastegate valve 41 having a diaphragm type actuator 42 is provided on the turbine side. A blower 40 is provided in the pressure chamber of the actuator 42.
The control pressure passage 44 from immediately downstream of b has an orifice 48 and communicates so as to open the wastegate valve 41 with good response when the supercharging pressure rises above a set value. The control pressure passage 44 further communicates a supercharging pressure with a duty solenoid valve 43 that leaks to the upstream side of the blower 40b. The duty solenoid valve 43 generates a predetermined control pressure to act on the actuator 42, thereby causing the waste gate valve to operate. 4
The supercharging pressure is controlled by changing the opening degree of No. 1. Here, the duty solenoid valve 43 is operated by a duty signal from an electronic control unit 100 described later, and when the duty ratio of the duty signal is small, the waste gate valve 4 is operated with a high control pressure.
1, the supercharging pressure is reduced by increasing the opening degree, and as the duty ratio increases, the control pressure is reduced by increasing the leak amount, and the supercharging pressure is increased by reducing the opening degree of the wastegate valve 41.

On the other hand, the intercooler 2 near the throttle valve 21 is provided downstream of the blower 40b in order to prevent a decrease in blower rotation and the occurrence of intake noise when the throttle valve is rapidly closed.
The bypass passage 46 is communicated between the outlet side of the blower 40b and the upstream side of the blower 40b. An air bypass valve 45 is provided in the bypass passage 46 so as to introduce a manifold negative pressure through the passage 47 when the throttle valve is rapidly closed, and to quickly leak pressurized air contained downstream of the blower.

An operation system of the secondary turbocharger 50 will be described. Similarly, the secondary turbocharger 50 is configured to supercharge the turbine 50a and the blower 50b by rotating the turbine 50a by the exhaust gas.
Is provided. A downstream-opening exhaust control valve 53 having a diaphragm actuator 54 is provided in the exhaust pipe 10 upstream of the turbine 50a, and a butterfly-type intake control valve having a similar actuator 56 downstream of the blower 50b. A boost pressure relief valve 57 is provided in a relief passage 58 between the upstream and downstream of the blower 50b.

The pressure operation system of each of these valves will be described. First, the surge tank 60 as a negative pressure source is connected to the check valve 62.
The valve 61 communicates with the intake manifold 23 through a passage 61 having a negative pressure, and stores a negative pressure and buffers a pulsating pressure when the throttle valve is fully closed. Further, a switching solenoid valve SOL. For the boost pressure relief valve for opening and closing the boost pressure relief valve 57. 1. Intake control valve 55
Switching solenoid valve for the intake control valve SOL. 2,
The first and second exhaust control valve switching solenoid valves SOL. 3, SOL. 4. Exhaust control valve 5
3 is provided with a duty solenoid valve 75 for small opening control, and a secondary wastegate switching solenoid valve 70 for opening and closing the secondary wastegate valve 51. Each switching solenoid valve 70, SOL. 1-4 are electronic control units 100
ON. An OFF signal is used to select the negative pressure of the negative pressure passage 63 from the surge tank 60, the positive pressure from the positive pressure passages 64a and 64b communicating with the intake control valve downstream, the atmospheric pressure, etc., and the actuators are controlled by the control pressure passages 70a to 74a. Then, the secondary wastegate valve 51, the supercharging pressure relief valve 57, and the control valves 55 and 53 are operated. The duty solenoid valve 75 variably controls the positive pressure acting on the positive pressure chamber 54a of the actuator 54 in accordance with a duty signal from the electronic control unit 100, and controls the exhaust control valve 53 to a small opening.

The switching solenoid valve SOL. 1, when the energization is turned off, the positive pressure passage 64a
The side is closed, the side of the negative pressure passage 63 is opened, and the negative pressure is guided to the pressure chamber in which the spring of the supercharging pressure relief valve 57 is housed via the control pressure passage 71a, so that the supercharging is performed against the urging force of the spring. The pressure relief valve 57 is opened. When it is turned on, the negative pressure passage 63 is closed, the positive pressure passage 64a is opened, and the positive pressure is introduced into the pressure chamber of the supercharging pressure relief valve 57 to close the supercharging pressure relief valve 57.

The switching solenoid valve SOL. 2
Is turned off, the atmosphere port is closed and the negative pressure passage 63 is closed.
Side of the actuator 5 through the control pressure passage 72a.
The intake control valve 55 is closed against the urging force of the spring by introducing a negative pressure into the pressure chamber in which the spring of No. 6 is housed.
When N is reached, the side of the negative pressure passage 63 is closed, the atmosphere port is opened, and the atmospheric pressure is guided to the pressure chamber of the actuator 56, so that the intake control valve 55 is opened by the urging force of the spring in the pressure chamber.

The secondary wastegate switching solenoid valve 70 is turned off only when the electronic control unit 100 determines that high-octane gasoline is used based on the ignition advance amount and the like.
If it is determined that regular gasoline is used,
N. When the secondary wastegate switching solenoid valve 70 is turned off, the passage 65 communicating upstream of the intake control valve 55 is closed to open the atmosphere port, and atmospheric pressure is introduced into the actuator 52 through the control pressure passage 70a. The secondary wastegate valve 51 is closed by the urging force of a spring disposed in the actuator 52. Also, when ON, the atmosphere port is closed and the passage 65 side is opened,
The supercharging pressure downstream of the secondary turbocharger 50 during operation of both turbochargers 40 and 50 is guided to the actuator 52,
The secondary wastegate valve 51 is opened according to the supercharging pressure, and when using regular gasoline, the supercharging pressure is relatively reduced as compared with when using high-octane gasoline.

Further, the first exhaust control valve switching solenoid valve SOL. The control pressure passage 73a from the exhaust control valve 53
The positive pressure chamber 54a of the actuator 54 that operates
Switching solenoid valve SOL. The control pressure passages 74a from the pressure chambers 4 communicate with the negative pressure chambers 54b containing the springs of the actuators 54, respectively. And, both switching solenoid valves SOL. When both 3 and 4 are OFF,
The first exhaust control valve switching solenoid valve SOL. 3 closes the positive pressure passage 64b and opens the atmosphere port, and the second exhaust control valve switching solenoid valve SOL. Numeral 4 closes the negative pressure passage 63 and opens the atmosphere port, whereby both chambers 54a and 54b of the actuator 54 are opened to the atmosphere, and the exhaust control valve 53 is fully closed by the urging force of the spring provided in the negative pressure chamber 54b. . Further, both switching solenoid valves SOL. 3 and 4 are both O
N, the atmosphere ports are closed, and the first exhaust control valve switching solenoid valve SOL. 3 opens the positive pressure passage 64b side, and the second exhaust control valve switching solenoid valve SOL. 4
By opening the side of the negative pressure passage 63, a positive pressure is introduced into the positive pressure chamber 54a and a negative pressure is introduced into the negative pressure chamber 54b of the actuator 54, and the exhaust control valve 53 is fully opened against the urging force of the spring.

The first exhaust control valve switching solenoid valve SOL. The orifice 67 is provided in the control pressure passage 73a from
The downstream side of the orifice 67 and the intake pipe 17 are provided.
a, a duty solenoid valve 75 for controlling the small opening of the exhaust control valve which is operated by a duty signal from the electronic control unit 100.
Are arranged. Then, the first switching solenoid valve SOL. When only 3 is ON and a positive pressure is supplied to the positive pressure chamber 54a of the actuator 54 and the negative pressure chamber 54b is opened to the atmosphere, the positive pressure is leaked by the duty solenoid valve 75 and the exhaust control valve 53 is slightly opened. Here, when the duty ratio in the duty signal is large, the duty solenoid valve 75 increases the positive pressure chamber 54 due to an increase in the amount of leakage.
The opening of the exhaust control valve 53 is reduced by decreasing the positive pressure acting on the valve a, and the opening of the exhaust control valve 53 is increased by increasing the positive pressure as the duty ratio decreases. When the engine operating state is within the predetermined exhaust control valve small-opening control region under the single turbo state in which only the primary turbocharger 40 is supercharged, the degree of opening of the exhaust control valve 53 by the duty solenoid valve 75 increases. The supply pressure is feedback-controlled, and the exhaust control valve 53 is opened slightly with the supercharging pressure control.

Various sensors will be described. A differential pressure sensor 80 is provided to detect a differential pressure between upstream and downstream of the intake control valve 55, and an absolute pressure sensor 81 is provided for the switching solenoid valve 7
6 to select and detect the intake pipe pressure and the atmospheric pressure.

A knock sensor 82 is attached to the engine body 1, and a water temperature sensor 83 faces a cooling water passage connecting the left and right banks 3, 4.
The sensor 84 is mounted. In addition, throttle valve 2
1. A throttle sensor 85 having a built-in throttle opening sensor and an idle switch for detecting that the throttle valve is fully closed.
, And an intake air amount sensor 86 is disposed immediately downstream of the air cleaner 15.

A crank rotor 90 is axially mounted on a crankshaft 1a supported by the engine body 1. A crank angle sensor 87 such as an electromagnetic pickup is provided on the outer periphery of the crank rotor 90. further,
A cam rotor 91 connected to a cam shaft of the valve mechanism 9 is provided with a cam angle sensor 88 for discriminating cylinders, which is composed of an electromagnetic pickup or the like.

Referring to FIG. 2, the structure of the intake system will be described in more detail. First, the right bank 3 of the engine main body 1 is offset from the left bank 4 so as to be shifted forward of the vehicle body, and a chamber 22 and an intake manifold 23 are installed on the engine main body 1. The intercooler 20 is of an air-cooling type that cools by cooling air flowing from an air scoop during traveling, and is installed horizontally at the rear of the engine main body having substantially the same height as the chamber 22. Connected to the chamber 22 via The primary turbocharger 40 is located immediately after the left bank 3 of the engine body 1 and on the left side of the intercooler 20,
The secondary turbochargers 50 are disposed immediately after the right bank 4 and on the right side of the intercooler 20 with the blower side facing forward of the vehicle body.

The intake pipe 16 from the air cleaner 15 passes under the intake manifold 23 on the right side and passes through two intake pipes 17.
a, 17b, and one intake pipe 17b is connected to the front end of the blower housing 50c of the secondary turbocharger 50, and another intake pipe 17 branched from the intake pipe 16.
is connected to the front end of the blower housing 40c of the primary turbocharger 40 by turning left. A primary-side intake pipe 18 and a secondary-side intake pipe 19 extend rearward from the sides of the blower housings 40c and 50c, respectively, below the intercooler 20, and connection portions 18a and 19a at their ends are connected to the intercooler 20. Each is connected to the lower rear. In this way, the intake system is configured so as to be routed rearward from the front of the vehicle body through the turbochargers 40 and 50 once, and then routed from the rear to the engine body 1 located forward through the intercooler 20, the throttle body 27 and the like. Is done.

Here, in a twin-turbo state in which the turbochargers 40 and 50 perform the supercharging operation, both the turbochargers 40 and 50 are in the twin turbo state.
The compressed air from 50 immediately flows into the intercooler 20 through the intake pipes 18 and 19. As described above, the primary turbocharger 40 is a low-speed type having a small turbo capacity Qp, and the supercharging pressure is controlled by the wastegate valve 41 so that the amount of passing air is relatively small. High-speed type with large Qs and large amount of passing air. Therefore, the primary side intake pipe 18 and the secondary side intake pipe 19
Are formed in a trumpet shape in which the opening area is sequentially increased, but the secondary side intake pipe 19 has a larger tendency to increase, and the connection portions 20a and 20 of the intercooler 20 to which both are connected.
The entrance areas A and B of b are set so that A <B. That is, the inlet area ratio B / A is set in proportion to the turbo capacity ratio Qs / Qp.

Next, the configuration of the electronic control system will be described with reference to FIG. The electronic control unit (ECU) 100
U101, ROM102, RAM103, backup RAM104, and the microcomputer which connected I / O interface 105 via the bus line are mainly comprised, and the constant voltage circuit 106 and the drive circuit 107 which supply predetermined | prescribed stabilized power supply to each part are provided. It is built in.

The constant voltage circuit 106 includes the ECU relay 9
5, and a relay coil of the ECU relay 95 is connected to the battery 96 via an ignition switch 97. The constant voltage circuit 10 is connected to the battery 96.
6 is directly connected, and the fuel pump 31 is connected via a relay contact of the fuel pump relay 98.

That is, when the ignition switch 96 is turned on and the ECU relay 95
When the relay contact of is closed, supply power for control,
When the ignition switch 97 is turned off, the power supply for backup is switched to the backup RAM 104.
To supply.

The I / O interface 105
Sensor 80-88, vehicle speed sensor 8
9 and a battery 96 are connected. Also, I / O
The igniter 36 is connected to the output port of the interface 105, and
CV25, injector 30, each switching solenoid valve 7
0, 76, SOL. 1-4, duty solenoid valve 4
3, 75 and the relay coil of the fuel pump relay 98 are connected.

Then, the ignition switch 97 is set to O
N, the ECU relay 95 is turned on and the ECU 100
Is turned on, a constant voltage is supplied to each unit via the constant voltage circuit 106, and the ECU 100 executes various controls.
That is, in the ECU 100, the CPU 101
Based on the control program stored in M102,
Various sensors 80 via the I / O interface 105
Input processing is performed on detection signals, battery voltage, and the like from -89, and various control amounts are calculated based on various data stored in the RAM 103 and the backup RAM 104 and fixed data stored in the ROM 102. Then, the fuel pump relay 98 is turned on by the drive circuit 107 to energize and drive the fuel pump 31, and the switching solenoid valves 70, 76, SOL. 1-4
ON. The OFF signal is supplied to the duty solenoid valve 43,
A duty signal is output to 75 to perform turbocharger operation number switching control and supercharging pressure control, and a drive pulse width signal corresponding to the calculated fuel injection pulse width is output to the injector 30 of the corresponding cylinder at a predetermined timing. And performs an ignition timing control by outputting an ignition signal to the igniter 36 at a timing corresponding to the calculated ignition timing, and outputs a control signal to the ISCV 25 to execute an idle speed control and the like. I do.

Next, regarding the operation, first, the ECU 100
Will be described. During the operation of the engine, as shown in FIG. 4, the engine speed N and the engine load Tp (basic fuel injection pulse width; = K × Q
(/ N, K are injector characteristic correction constants, and Q is an intake air amount) The operating range is from a single turbo state where only the primary turbocharger 40 is supercharged to a twin state where both turbochargers 40 and 50 are supercharged. In the single turbo range, which is in a lower speed range than the single-to-twin switching line L2 for switching to the turbo state, and as shown in FIG. 5, a single-to-twin switching determination line L2 and a preset intake pipe pressure P1 and engine speed are set. When the engine is in a low-speed, low-load area outside the small opening control area of the exhaust control valve surrounded by N1,
Four switching solenoid valves SOL. 1-4 are all OF
F. Thus, the boost pressure relief valve 57 is provided with a boost pressure relief valve switching solenoid valve SOL. 1 turns off, the negative pressure from the surge tank 60 is introduced into the pressure chamber, thereby opening the valve against the urging force of the spring.
Is an intake control valve switching solenoid valve SOL. 2 OFF
As a result, a negative pressure is introduced into the pressure chamber of the actuator 56, whereby the valve is closed against the urging force of the spring. Further, the exhaust control valve 53 is provided with a switching solenoid valve SOL. When the atmospheric pressure is introduced into both chambers 54a and 54b of the actuator 54 by turning off the switches 3 and 4, the valve is closed by the urging force of the spring. Then, by closing the exhaust control valve 53, the introduction of exhaust gas to the secondary turbocharger 50 is shut off, the secondary turbocharger 50 becomes inactive, and only the primary turbocharger 40 is in a single turbo state in which the turbocharger operates. Become. And the primary turbocharger 4
A high shaft torque can be obtained in a low speed region by the supercharging operation of only 0. Further, the closing of the intake control valve 55 prevents the supercharging pressure from the primary turbocharger 40 from leaking to the secondary turbocharger 50 via the intake control valve 55, thereby preventing a decrease in the supercharging pressure. Is done.

When the engine speed N and the engine load Tp increase and enter the exhaust control valve small opening control region, the first
Switching solenoid valve SOL. ON only 3
I do. Therefore, the exhaust control valve 53 is opened by introducing a positive pressure into the positive pressure chamber 54a of the actuator 54. At this time, the duty solenoid valve 75 opens the exhaust control valve 53.
The positive pressure acting on the positive pressure chamber 54a is regulated, the exhaust control valve 53 is opened slightly, and the secondary turbocharger 50 is pre-rotated. Further, at this time, since the boost pressure relief valve 57 is opened, the compressor pressure by the secondary turbocharger 50 due to the preliminary rotation is leaked, and the preliminary rotation is facilitated.

When the operating range based on the engine speed N and the engine load Tp shifts from the single turbo range to the twin turbo range with the single-to-twin switching line L2 as a boundary (see FIG. 4), the boost pressure relief valve is immediately used. Switching solenoid valve SOL. 1 is turned on, and the supercharging pressure relief valve 57 is closed. In synchronization with this, the exhaust control valve small opening control duty solenoid valve 75 is fully closed and the positive pressure through the positive pressure passage 64b is directly introduced into the positive pressure chamber 54a of the actuator 54 without leaking. The opening degree of the exhaust control valve 53 is increased. The closing of the boost pressure relief valve 57 shuts off the relief passage 58, and the opening degree of the exhaust control valve 53 increases the rotation speed of the secondary turbocharger 50 to increase the secondary turbocharger upstream of the intake control valve 55. The compressor pressure by the supercharger 50 is gradually increased to prepare for transition to the twin turbo state. After a lapse of a predetermined time, the second exhaust control valve switching solenoid valve SOL. 4 is turned on to fully open the exhaust control valve 53,
Further, the preliminary rotation speed of the secondary turbocharger 50 is increased. Further, after a lapse of a predetermined time, the compressor pressure by the secondary turbocharger 50 increases, and the intake control valve 55
When the differential pressure between the upstream pressure and the downstream pressure of the intake control valve reaches a set value, the intake solenoid control valve switching solenoid valve SOL. 2 is turned on to open the intake control valve 55, and the secondary turbocharger 50 performs the supercharging operation in addition to the supercharging operation of the primary turbocharger 40. As a result, in a region where the exhaust flow rate is high in a high speed region, a high shaft torque is obtained by the supercharging operation of the turbochargers 40 and 50, and the output is improved.

The engine speed N and the engine load T
When the engine operating region shifts from the twin turbo region to the twin turbo single switching region L1 (see FIG. 4) and the engine operating region shifts to the single turbo region side after a predetermined time,
Switching solenoid valves SOL. 1 to 4 are turned off.
Thereby, the supercharging pressure relief valve 57 is opened, the exhaust control valve 53 and the intake control valve 55 are both closed, and the supercharging operation of the secondary turbocharger 50 is stopped, and the primary turbocharger 40 Only the supercharging operation returns to the single turbo state.

In regard to the supercharging pressure control, in the exhaust control valve small opening control region under the single turbo state, the change in the supercharging pressure due to the small opening of the exhaust control valve 53 is large. The valve is closed, and in this state, a duty signal by PI control is given to the duty solenoid valve 75 based on the target boost pressure and the actual boost pressure, and the boost pressure is feedback-controlled using only the exhaust control valve 53. Also, when a single turbo state is outside the exhaust control valve small opening control area, and under a twin turbo state, a duty signal by PI control is given to the duty solenoid valve 43 on the primary turbocharger 40 side as described above, The boost pressure is feedback-controlled by the wastegate valve 41 of the primary turbocharger 40.

Further, as described above, the two turbochargers 4
In the twin turbo state where the turbochargers 0 and 50 perform the supercharging operation, the air Ap and As sucked into the two blower housings 40c and 50c and compressed flow into the intercooler 20 through the intake pipes 18 and 19, respectively. At this time, the secondary turbocharger 50 generates a large amount of compressed air As because the turbo capacity Qs is large and the intake pipe length upstream of the blower is short, but the primary turbocharger 40 has the turbo capacity Qp
And the boost pressure is controlled by the waste gate valve 41, so that the amount of the compressed air Ap decreases. Here, since the inlet areas A and B of the intercooler 20 are set corresponding to the turbo capacities Qp and Qs, both the large amount of compressed air As on the secondary side and the small amount of compressed air Ap on the primary side cause pressure fluctuation. Intercooler 20 smoothly without air
Flow into and gather together. Therefore, when a plurality of turbochargers 40 and 50 having different turbo capacities are provided in the intake system, and they are gathered together by the intercooler 20, the compressed air of the entire intake system is smoothly reduced in a state where the intake resistance is small. And is supplied to each cylinder of the engine body 1, thereby improving the intake efficiency.

In the intercooler 20, both compressed air A
By combining p and As into one, as in the case of a horizontally opposed four-cylinder engine, the turbocharger is arranged according to the ignition order of the cylinders in the left and right banks 3 and 4, for example, in the order of # 1 → # 3 → # 2 → # 4 cylinder. Even when the feeders 40 and 50 operate alternately, a large amount of the averaged compressed air Ac is continuously and uniformly obtained. The collected compressed air Ac is cooled by the cooling air in the intercooler 20 to increase the air density. In this state, the compressed air Ac is pressure-fed to each cylinder of the engine body 1 and supercharged to substantially increase the charging efficiency. You.

Referring to FIG. 6, a second embodiment of the present invention will be described. This embodiment is a primary turbocharger 4
This is a case where the turbo capacity Qp of 0 is large and the turbo capacity Qs of the secondary turbocharger 50 is set small.
In this case, the inlet areas A and B of the connecting portions 20a and 20b of the intercooler 20 to which the two intake pipes 18 and 19 are connected.
Are set to A> B in accordance with the magnitude relationship of the turbo capacity.

Referring to FIG. 7, a third embodiment of the present invention will be described. This embodiment is a primary turbocharger 4
0 and the turbo capacity Qp, Q of the secondary turbocharger 50
This is the case where s is set to be the same. In this case, the inlet areas A and B of the connecting portions 20a and 20b of the intercooler 20 to which the two intake pipes 18 and 19 are connected are set to A = B in accordance with the magnitude relationship of the turbo capacity. Therefore, the second
Also in the case of the third embodiment, when both turbochargers 40 and 50 perform the supercharging operation under the twin turbo state, both of the compressed air Ap and As smoothly flow into the intercooler 20. They come together and have high intake efficiency.

Although the embodiment of the present invention has been described above, the present invention can be applied to engines other than the horizontally opposed type and other supercharging control systems. The arrangement of a plurality of turbochargers and intercoolers and the routing of the intake system are not limited to the embodiments. Furthermore, the present invention is not limited to this embodiment, and can be applied to a normal twin turbo engine that always operates a plurality of turbochargers.

[0041]

[Effect of the invention] As described above, according to the invention,
In an intake device in which intake pipes from a plurality of turbochargers are respectively connected to an intercooler, an inlet area ratio of an intercooler to which each intake pipe is connected is set in proportion to a turbo capacity ratio, and a plurality of turbochargers are provided. Even when the turbocharger capacities are different, the compressed air flows into the intercooler smoothly and collects, so that the intake resistance of the entire intake system is reduced, the intake efficiency is improved, and the output characteristics are improved. Is improved. Since only the opening areas of the plurality of intake pipes and the intercooler are set, the structure is simple.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a supercharged engine to which the present invention is applied.

FIG. 2 is a plan view of a main part of the first embodiment of the intake device according to the present invention;

FIG. 3 is a circuit diagram of a control system of a supercharged engine.

FIG. 4 is an explanatory diagram showing a switching area between a single turbo state and a twin turbo state.

FIG. 5 is an explanatory diagram showing an exhaust control valve small opening control region.

FIG. 6 is a plan view of a main part showing a second embodiment of the present invention.

FIG. 7 is a plan view of a main part showing a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine main body 18 Primary intake pipe 19 Secondary intake pipe 20 Intercooler 23 Intake manifold 27 Throttle body 40 Primary turbocharger 50 Secondary turbocharger

Claims (2)

(57) [Scope of request for utility model registration] 1. A plurality of turbochargers in the vicinity of the engine body is disposed, blower discharge side of the turbocharger is connected to the inlet side of the intercooler via an intake pipe, the intercooler outlet In the intake device of a supercharged engine having a side connected to an engine body via a throttle body and an intake manifold, an inlet area ratio of an intercooler to which each intake pipe from each turbocharger is connected is represented by each intake pipe. An intake system for a turbocharged engine, wherein the intake air system is set in proportion to a turbo capacity ratio of a turbocharger to be connected. 2. The turbocharger according to claim 1, wherein said plurality of turbochargers are a primary turbocharger having a small turbo capacity and a secondary turbocharger having a large turbo capacity. The inlet area of the intercooler to which the primary-side intake pipe is connected is set to be small, and the entrance area of the intercooler to which the secondary-side intake pipe from the secondary turbocharger is connected is set to be large. 2. The intake device for a supercharged engine according to 1.