JPH06207522A - Turbocharger control device - Google Patents

Abstract

PURPOSE:To increase boost pressure in a low speed rotational range, and also suppress reduction of boost pressure when operation is switched from a small sized turbocharger to a large sized turbocharger. CONSTITUTION:When an engine rotational speed is in a low speed rotational range, a small sized turbocharger 1 is operated, and simultaneously, a power generator/motor 17 is operated as a motor so as to increase boost pressure. When the engine rotational speed exceeds the low speed rotational range, such a switch process is carried out as stopping the small sized turbocharger 1 and operating a large sized turbocharger 2, and then the power generator/motor-17 is operated as a motor to suppress reduction of boost pressure. The power generatior/motor-17 is operated as a power generator so as to recover energy when the engine rotational speed is in a high speed rotational range and an engine brake is operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbocharger control device having a turbocharger equipped with a turbine, a compressor and a generator / motor, and a turbocharger equipped with a turbine and a compressor.

[0002]

2. Description of the Related Art A turbocharger is designed to forcibly send air above normal into the cylinder of an engine to increase the output of the engine and to improve fuel economy.
Generally, it has a structure as shown in FIG. That is,
The turbocharger 30 connects the compressor 32 and the turbine 33 with a shaft 35, and rotatably supports the shaft 35 in a housing 31 via a bearing 34. Further, referring to FIG. 16, the turbine 33 is rotated by the exhaust energy of the exhaust gas from the engine 37, and the compressor 32 coaxial with the turbine 33 is rotated accordingly. The intake air that has passed through the air cleaner is compressed by the compressor 32, sent out from the turbocharger 30, cooled by the intercooler 36, and then supplied as compressed air into the cylinder of the engine 37. As the engine speed increases, the amount of exhaust gas also increases, the rotation speed of the turbine 33 increases, and the boost pressure increases accordingly, increasing the engine output.

FIG. 11 is a graph showing changes in torque (BMEP) with respect to engine speed. Generally, an engine equipped with a turbocharger has a lower torque (broken line b) than the engine base torque (solid line a) in the extremely low speed range (about 600 rpm), that is,
Only 5-10% lower torque than usual can be obtained. Therefore,
Even in the extremely low speed rotation range where the engine exhaust gas flow rate is small, V was developed to obtain boost pressure rise.
It is a turbocharger with GS. This turbocharger with VGS is equipped with a flow rate variable adjusting means VGS at the nozzle inlet of the turbine, and the inlet of the turbine can be narrowed or opened by controlling the nozzle. The alternate long and short dash line c in FIG. 11 shows the torque of this turbocharger with VGS. The torque in the extremely low speed rotation range is improved, which can considerably improve the driving feeling at the time of starting.

However, even a turbocharger with VGS has a limit in improving the torque. This is because one turbine and compressor control from the extremely low speed rotation range to the high speed rotation range. That is, in terms of the compressor characteristics, as shown in FIG. 10, the pressure ratio (boost pressure) of the compressor enters the surge zone, which makes it impossible to further improve the boost pressure. As a result, the improvement in torque was limited to the line indicated by the thick solid line d in FIG. 11 at most.

On the other hand, a turbocharger with a generator / motor has been developed from the past (see, for example, Japanese Patent Laid-Open No. Sho 63).
-272907, JP-A-1-219318, etc.). The structure of this turbocharger with a generator / motor will be described with reference to FIG. A turbocharger 39 with a generator / motor shown in FIG. 17 includes a turbine 40 driven by exhaust gas energy of an engine,
A supercharged compressor 41 and a shaft 42, which are connected to the turbine 40 through a shaft 42, are attached to the housing 4
3, a bearing 44 rotatably supported on the shaft 3 and a generator / motor 45 arranged on the shaft 42. The generator / motor 45 includes a rotor 46 of a permanent magnet that rotates integrally with the shaft 42, and a stator 47 fixed to the housing 43.

This turbocharger with generator / motor 3
9 is that the rotational speed of the compressor 41, that is, the boost pressure can be controlled by operating the generator / motor 45 independently of the engine conditions (load, rotational speed, etc.). Therefore, the turbocharger 39 can increase the boost pressure even when the engine is stopped or idling. This is called "flying boost up", and a certain amount of boost pressure is secured by energizing in advance about one second before starting and operating the generator / motor 45 to increase the rotation speed of the turbocharger. Is possible.

However, when the turbocharger with a generator / motor is applied to a large engine, the turbocharger itself becomes large, and as shown in FIG.
If the intake air amount (air flow rate) of air on the engine side is small, the pressure ratio (boost pressure) will stick out of the surge line and enter the surge zone, no matter how much the compressor side is rotated, and the pressure ratio will increase. I can't. With this, the power of flying boost up will be halved. Further, as the turbocharger becomes larger, the electric motor part also becomes larger, resulting in a cost increase.

As described above, whether it is a turbocharger with VGS or a turbocharger with a generator / motor, when only one turbocharger is used, a sufficient boost pressure is obtained in the extremely low speed rotation range. There is a problem that you cannot get it. On the other hand, what is called a sequential turbocharger device using two turbochargers has been developed. This sequential turbocharger device has a small capacity or small size and a large capacity or large size.
It is provided with a single turbocharger, and for example, it can be controlled so that a low speed torque is increased by a small turbocharger and switched to a large turbocharger at high speed. This sequential turbocharger has no restrictions on where to place the two turbochargers, is small and has low cost, and future prospects are expected, but when switching from a small turbocharger to a large turbocharger Boost pressure drops,
There is a problem that a valley of torque is created, and how to make this valley smaller is an issue.

[0009] As a countermeasure against this, conventionally, for example, Japanese Patent Laid-Open No.
There is one disclosed in Japanese Patent Publication No. 1-294136. This sequential turbocharger device switches the turbocharger to be operated according to the increase in the operating load of the diesel engine. First, the engine load is 33%.
Runs a small turbocharger up to 33% load
To 66%, a large turbocharger is operated, and when the load exceeds 66%, both small and large turbochargers are operated. However, with this measure, the valley of the torque cannot be made sufficiently small, and the problem that smoke occurs when the turbocharger is switched still remains.

[0010]

Therefore, since there is a limit in improving the torque in the extremely low speed rotation range with one turbocharger, two turbochargers, a small turbocharger and a large turbocharger, are switched. In addition to adopting a so-called sequential turbocharger device that controls operation by means of a small turbocharger, it is possible to increase boost pressure more quickly than a large turbocharger. It is necessary to solve the problem of preventing the boost pressure from entering the surge zone in the extremely low speed rotation range by configuring the small turbocharger that can obtain the boost pressure. There is also a need to solve the problem of the sequential turbocharger device, that is, the problem of preventing a drop in boost pressure that occurs when switching from a small turbocharger to a large turbocharger.

Therefore, an object of the present invention is to provide a turbocharger control device provided with two turbochargers, a small capacity turbocharger and a large capacity turbocharger.
In order to solve the above problems, a generator / motor is provided in a small-capacity turbocharger, and the pressure ratio is adjusted until the torque desired by the user (torque shown by diagonal line e in FIG. 11) is obtained in the low speed range of the engine speed. It is an object of the present invention to provide a turbocharger control device that can be increased and that can prevent smoke from occurring when switching from a small capacity turbocharger to a large capacity turbocharger.

[0012]

In order to achieve the above object, the present invention is configured as follows. That is,
The present invention relates to a small capacity turbocharger including a turbine, a compressor and a generator / motor, a large capacity turbocharger including a turbine and a compressor, a rotation sensor for detecting an engine speed, and an engine speed detected by the speed sensor. Controls the small capacity turbocharger in response to a low speed range lower than a preset rotational speed and operates the large capacity turbocharger in response to a rotational speed exceeding the low speed range, and engine rotation The present invention relates to a turbocharger control device, comprising: a controller that controls the operation of the electric generator / motor according to the number of electric motor operation or generator operation.

In the turbocharger control device, the controller controls the generator / motor as an electric motor in response to a low engine speed range.

Further, in this turbocharger control device, the controller controls to operate the generator / motor as a generator in response to a high engine speed range at least.

Further, in this turbocharger control device, the controller controls to operate the generator / motor as a generator when the engine brake is operated.

Further, in this turbocharger control device, the controller responds to a change in the engine speed from the low speed region to the medium speed region when switching from the small capacity turbocharger to the large capacity turbocharger. Until the rotation speed or boost pressure of the large-capacity turbocharger reaches a preset predetermined value, the generator / motor of the small-capacity turbocharger is operated as an electric motor, and gas is supplied from the small-capacity turbocharger to the large-capacity turbocharger. The control is to send in.

Alternatively, in this turbocharger control device, the controller responds to a change in engine speed from a low speed region to a medium speed region when switching from the small capacity turbocharger to the large capacity turbocharger. Until the rotational speed or boost pressure of the large capacity turbocharger reaches a preset predetermined value, the large capacity turbocharger is operated, the compressor side passage of the small capacity turbocharger is closed and the turbine inlet side passage is opened, The generator / motor of the small capacity turbocharger is operated as an electric motor to rotate in the reverse direction, and gas is controlled to be fed from the turbine of the small capacity turbocharger to the turbine inlet side of the large capacity turbocharger.

[0018]

The turbocharger control device according to the present invention is
Since it is configured as described above, it operates as follows. That is, in this turbocharger control device, the small capacity turbocharger operates when the engine speed is in the low speed range. Since the passage area of the turbine nozzle of the small capacity turbocharger is small, the boost pressure can be sufficiently increased even in the low speed range. In addition, the boost pressure can be further increased because the generator / motor is configured to operate in the low speed range. Therefore, the relationship between the air flow rate of the compressor and the pressure ratio becomes the relationship as shown in FIG. 12, and the boost pressure does not enter the zone protruding from the surge line. Therefore, in the low speed region of the engine speed, the diagonal line e in FIG.
The desired torque indicated by is obtained.

When the engine speed exceeds the low speed range,
The small capacity turbocharger is stopped and the large capacity turbocharger is operated. If you simply switch from a small-capacity turbocharger to a large-capacity turbocharger, the boost pressure will drop drastically at the time of switching, but until the rotational speed or boost pressure of the large-capacity turbocharger reaches a specified value, The boost pressure of the large-capacity turbocharger is sharply increased because the generator / motor of the turbocharger is operated as a motor and the gas is sent from the small-capacity turbocharger to the large-capacity turbocharger. Therefore, although a slight drop in boost pressure occurs when switching,
Immediately increased to a predetermined value.

In the high-speed rotation range of the engine, the large-capacity turbocharger operates, but it is over boosted.
However, since the generator / motor of the small-capacity turbocharger is configured to operate as a generator, the amount of overboost can be regenerated to the battery, the auxiliary machine, or the like.

Since the generator / motor of the small capacity turbocharger is operated as the generator even when the engine brake is operated, the braking force of the engine brake can be regenerated to the battery, the auxiliary machine and the like.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a turbocharger control device according to the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic structural diagram showing an embodiment of a turbocharger control device according to the present invention. This turbocharger control device relates to a control device of a sequential turbocharger including two turbochargers, a small capacity turbocharger or small turbocharger 1 and a large capacity turbocharger or large turbocharger 2. The exhaust pipe 4 connected to the engine 3 is provided with a turbine inlet valve 5 and a turbine inlet valve 6, communicated with the turbine 7 of the small turbocharger 1 through the turbine inlet valve 5, and through the turbine inlet valve 6 with the large turbocharger 2. Is communicated with the turbine 9. The large turbocharger 2 may be provided with a variable nozzle device VGS that makes the passage area to the turbine 9 variable. The exhaust gas discharged from the engine 3 is supplied to the turbine 7 when the turbine inlet valve 5 is opened, and is supplied to the turbine 9 when the turbine inlet valve 6 is opened. The gas discharged from the turbine 7 is discharged to the outside when the turbine outlet valve 8 is open, and is sent to the turbine 9 of the large turbocharger 2 when the turbine outlet valve 8 is closed.

Compressor 1 of small turbocharger 1
The air compressed at 0 is supercharged to the engine 3 through the intake pipe 12 when the compressor outlet valve 11 is open. When the compressor outlet valve 11 is closed, the compressed air is supplied to the compressor 13 of the large turbocharger 2. The exhaust gas discharged from the engine 3 is fed to the turbine inlet valve 6
The air that is supplied to the turbine 9 when is opened and is compressed by the compressor 13 of the large turbocharger 2 is supercharged to the engine 3 through the intake pipe 12 when the compressor outlet valve 15 is opened. The intake pipe 12 is provided with an intercooler 16 so that the compressed air is cooled by the intercooler 16 before being supercharged to the engine 3.

The small turbocharger 1 is equipped with a generator / motor 17 having both functions of an electric motor and a generator (in the figure, a turbocharger having a generator / motor is represented by the symbol TCG. Exist). Power generation
The electric motor 17 has a rotor 18 that is a permanent magnet and a stator 19 that is a coil. When the exhaust energy from the engine 3 drives the turbine 7, the rotor 18 is driven to rotate and the stator 19 regenerates AC power. , Is stored in the battery, or consumed by auxiliary equipment. In this case, the generator / motor 17 is driven as a generator. When the rotor 18 is driven by the electric power from the battery, the intake air is compressed by the operation of the compressor 10 and is supercharged to the engine 3 via the intake pipe 12. In this case, the generator / motor 17 is operated as an electric motor. Since the small turbocharger 1 is provided with the generator / motor, the generator / motor itself can be miniaturized. As can be understood from FIG. 14, the reason why the generator / motor 17 is provided in the small turbocharger 1 without being provided in the large turbocharger 2 is as follows. This is because the power generation capacity of the small turbocharger 1 is superior to that of the large turbocharger 2.

FIG. 6 shows the configuration of a controller for controlling the operation switching of the small turbocharger 1 and the large turbocharger 2 and the switching control of the generator / motor, and the interrelationship between the controller and various detectors and various valves. It is a block diagram shown. When the engine speed from the rotation sensor 22 is input at times other than idling rotation, the accelerator pedal sensor 20 must be zero (in the case of a gasoline engine, the throttle position sensor can use the fully closed detection signal). Is detected and an engine brake operation signal is issued. Boost pressure sensor 21
Detects the boost pressure and transmits the detected value. The rotation sensor 22 detects the engine speed and sends a detection value.
The controller 24 responds to the detection signals from the accelerator pedal depression sensor 20, the boost pressure sensor 21, and the rotation sensor 22, in response to the turbine inlet valves 5 and 6, the turbine outlet valve 8, the compressor outlet valves 11 and 15, and the compressor inlet valve 14. The control for switching the opening and closing operations such as the above is performed.

The controller 24 uses the rotation range discriminating means 2
5, boost pressure comparison means 26, engine brake discrimination means 27, TCG control means 28, valve switching control means 29, etc. The rotation speed determination unit 25 detects which rotation speed of the engine 3 detected by the rotation sensor 22 is a low speed rotation speed range (low speed range), a medium speed rotation range (medium speed range), or a high speed rotation range (high speed range). It is discriminated whether or not it belongs to the range, and a signal corresponding to each rotation range is issued. Boost pressure comparison means 2
Reference numeral 6 compares the boost pressure detected by the boost pressure sensor 21 with a set value, and issues a signal when the detected value exceeds the set value. This comparison is performed when a low speed rotation range signal or a medium speed rotation range signal is input from the rotation range determination means 25.
The engine brake discriminating means 27 receives an engine speed detection signal from the rotation sensor 22 other than during idling and a detection signal indicating that the accelerator pedal depression amount is zero from the accelerator depression sensor 20.
Issue an engine brake signal.

The turbocharger control means 28 controls the generator / motor 17 of the small turbocharger 1 to operate as a generator when an engine brake signal is input from the engine brake determination means 27. The turbocharger control during engine braking is prioritized over other controls. The turbocharger control means 28 controls the generator / motor 17 of the small turbocharger 1 to operate as a generator even when a high speed rotation range signal is input from the rotation range determination means 25. Further, when the low speed rotation range signal is input from the rotation range determination means 25, the turbocharger control means 28 operates the generator / motor 17 of the small turbocharger 1 as an electric motor. Further, the turbocharger control means 28, when the medium speed rotation range signal is input from the rotation range determination means 25,
The generator / motor 17 is operated as an electric motor, and when a signal is input from the boost pressure comparison means 26 on the way, the operation of the small turbocharger 1 is controlled to be stopped.

The valve switching control means 29 is the rotation range discrimination means 2
Small turbocharger 1 depending on the type of signal from 5
Turbine inlet valve or turbine inlet valve 5, turbine outlet valve 8, compressor outlet valve 11, and turbine inlet valve 6 for large turbocharger 2, compressor outlet valve 1
A signal for controlling the opening / closing of the switch 5 is issued to the changeover switch 23. Further, the valve switching control means 29, when the engine brake signal is input from the engine brake determination means 27,
The turbine inlet valve 5 for the small turbocharger 1 is opened, the turbine outlet valve 8 is opened, and the compressor outlet valve 1
Control to close 1 is performed. Also, the valve switching control means 2
Reference numeral 9 controls to close the turbine inlet valve, that is, the switching valve 5 when a signal is input from the boost pressure comparing means 26.

Next, the operation of this turbocharger controller will be described. 1 to 4 are schematic diagrams showing the operating states of the small turbocharger 1 and the large turbocharger 2. FIG. 1 shows an operating state in the low speed rotation range. 2 and 3 show the operating state in the medium speed rotation range, FIG. 2 shows the operating state when switching from the small turbocharger to the large turbocharger, and FIG. 3 shows the operating state of only the large turbocharger after switching. Shows. Further, FIG. 4 shows an operating state in the high speed rotation range.
In the figure, arrows indicate the flow of exhaust gas discharged from the engine and the flow of compressed air supercharged to the engine. It will be understood from FIG. 13 why the turbocharger operated in the low speed rotation range is not the large turbocharger 2 but the small turbocharger 1. FIG. 13 shows the boost pressure increase rate with respect to the elapsed time from the start of operation of the turbocharger. It can be seen that the boost pressure of the small turbocharger 1 increases faster than that of the large turbocharger 2. As described above, the small turbocharger 1 can quickly increase the boost pressure, and thus is suitable for operation in the low speed rotation range.

The operation of the turbocharger controller will be described with reference to the flow charts shown in FIGS. 7A, 7B and 8. First, control in the low speed rotation range of the turbocharger control device will be described with reference to FIGS. 1, 7A and 7B. When the engine is started, the turbine inlet valve 5, turbine outlet valve 8, compressor outlet valve 11 and compressor outlet valve 15 at the turbine inlet of the small turbocharger 1 are all opened, and the turbine inlet turbine of the large turbocharger 2 is at the turbine inlet. The inlet valve 6 is reset to the closed state (step 1). In this state, the exhaust gas flows to drive the turbine 7 as indicated by the arrow in FIG. 1, and the compressor 10 also rotates accordingly. As a result, the air compressed by the compressor 10 flows through the path indicated by the arrow and is supercharged to the engine 3. Next, the rotation speed of the engine 3 is detected by the engine rotation speed sensor 22 (step 2), and the detected engine rotation speed N is input to the rotation range determination means 25.
It is determined whether or not the engine speed N exceeds a preset speed N _{0, that} is, a low speed rotation range (step 3).

In the low speed rotation range, the boost pressure detector 21 detects the boost pressure (step 4). The boost pressure comparing means 26 makes a comparison as to whether or not the detected boost pressure BP exceeds a preset boost pressure BP _{0, that} is, a set value (step 5), and when it does not exceed the set value, a small turbocharger. The first generator / motor 17 is operated as a motor (step 6). At this time, the compressor 10 uses the power from the exhaust gas to generate electricity / motor 17
Since the rotational force of the electric motor is applied, the compressor 10 rotates at a higher speed, and a high boost pressure can be obtained in the low speed rotation range. Therefore, the two-point diagonal line e in FIG.
The torque indicated by can be obtained. On the other hand, boost pressure B
When P exceeds the set value BP ₀ , the operation of TCG is stopped (step 7). Therefore, the electric motor operation of the generator / motor 17 is stopped, and only the small turbocharger 1 is operated.

When the engine speed N exceeds the set speed N ₀ in the low speed rotation range, control in the medium speed rotation range is performed. The turbine outlet valve 8 and the compressor outlet valve 11 of the small turbocharger 1 are closed, and the turbine inlet valve 6, the three-way compressor inlet valve 14 and the compressor outlet valve 15 of the large turbocharger 2 are opened (step 8). That is, this turbocharger control device is switched to operate from the small turbocharger 1 to the large turbocharger 2. At the same time, the generator / motor 17 of the small turbocharger 1 is operated as a motor (step 9). In this state, the exhaust gas flows through the path shown by the arrow in FIG. That is, the exhaust gas is directly supplied to the turbine 9 and, at the same time, the exhaust gas is forcibly supplied to the turbine 9 via the turbine 7 by operating the generator / motor 17 as an electric motor. Further, the compressed air sent from the compressor 10 is supplied to the compressor 13 and supercharged to the engine 3 together with the air compressed by the compressor 13. Therefore, when the small turbocharger 1 is switched to the large turbocharger 2, the generator / motor 17 operates as a motor to rapidly increase the boost pressure, and it is possible to suppress a drop in the boost pressure when the turbocharger is switched.

Next, the boost pressure BP is detected (step 10), and it is determined by comparison whether the detected value BP exceeds the set value BP ₀ (step 11). When the detected boost pressure BP is larger than the set value BP ₀ , the turbine inlet valve 5 of the small capacity turbocharger 1 is closed (step 12) and the operation of the generator / motor 17 is stopped (step 13). In this state, as shown in FIG. 3, only the large turbocharger 2 is operated. That is, the exhaust gas from the engine 3 is supplied to the turbine 9 of the large turbocharger 2, and the turbine 9 and the compressor 13 rotate at high speed, while the compressor 13
The air compressed by is supercharged to the engine 3.

Subsequently, the engine speed N is detected by the rotation sensor 22 (step 14), and the rotation range discriminating means 25 determines whether or not the preset high speed range of the rotation number N _H has been reached (step 14). 15). When the high speed rotation range is reached, both the turbine inlet valve 5 and the turbine outlet valve 8 of the small turbocharger 1 are opened (step 16) to generate electricity.
The electric motor 17 operates as a generator (step 17).
That is, while the large turbocharger 2 continues to operate as it is, exhaust gas is supplied to the turbine 7 of the small turbocharger 1 as shown by an arrow in FIG.
Rotates at high speed, and the generator / motor 17 operates as a generator. Therefore, the overboost can be regenerated by the power generator / motor 17. Further, the air compressed by the compressor 10 is supplied to the compressor 13 through the compressor inlet valve 14 to the inlet side of the compressor 13.

As described above, in the low speed rotation range, the small turbocharger 1 is operated and the generator / motor 17 is operated.
Is driven by an electric motor. When the low speed rotation range is switched to the medium speed rotation range, the large turbocharger 2 is operated and the generator / motor 17 of the small turbocharger 1 is operated as an electric motor. When the boost pressure stabilizes in the medium speed range, only the large turbocharger 2 operates. When the high speed rotation range is reached, the large turbocharger 2 continues to operate and the generator / motor 17 of the small turbocharger 1 is operated as a generator.

If the vehicle decelerates midway, the operation is controlled as follows. For example, let's look at a case where the vehicle is decelerated when switching from the low speed rotation range to the medium speed rotation range. First, the engine speed is detected (step 18), it is determined whether the detected engine speed exceeds the low speed range, and if the engine speed is in the low speed range, the process proceeds to step 1
If the engine speed remains in the medium speed range, the process returns to step 9 (step 19). Also,
When the engine speed is in the low speed range when decelerating from the medium speed range, the process returns to step 1 (step 20). When decelerating from the high speed rotation range, the engine speed N is detected (step 21), it is determined whether the detected engine speed N is in the medium speed rotation range N _{0 to} N _H , and the engine speed is changed to the medium speed rotation range. is optionally When the process returns to step 8 (step 22), returns to a if it is, low-speed rotation range 0 to N _0, if left in the high speed range N _H to N _MAX, the generator-motor 17 is a generator Is continued (step 23).

When the engine brake is activated while the turbocharger control device is performing the above-mentioned operation control, the control is performed according to the flowchart of FIG. The control of the turbocharger control device will be described below with reference to the flowchart of FIG.
When the engine 3 starts, the engine brake discriminating means 2
7 always determines whether or not the engine brake is operating. When the engine speed is input by the rotation sensor 22 and the accelerator depression sensor 20 detects that the depression amount of the accelerator pedal is zero except when idling (step 24), that is, when the engine brake operates, By the valve switching control means 29, both the turbine inlet valve 5 and the turbine outlet valve 8 are opened, the compressor outlet valve 11 is closed (step 25), and the turbocharger operation control means 28 causes the generator / motor 17 to operate. It operates as a generator (step 26). Then, while the accelerator pedal depression amount is zero except during idling (step 27), the generator / motor 17 continues to operate as a generator. Therefore, while the engine brake is operating, the generator / motor 17 always operates as a generator to regenerate electric power.

When it is detected that the throttle valve is open (step 27), the engine brake is not in operation, so the operation control returns to the flowchart of FIG. Therefore, it is determined where to return to in the flowchart of FIG. First, to detect the engine speed N (step 28), the engine speed N to determine whether high speed range N _H to N _MAX (step 29). If it is in the high speed rotation range N _{H to} N _MAX , the process returns to step 17. When it is not in the high-speed rotation range, the generator operation of the generator / motor 17 is stopped (step 3).
0). Subsequently, it is determined whether the engine speed is in the low speed rotation range _{0 to} N _{0. If} the engine speed is in the low speed rotation range _{0 to} N ₀ , the process returns to step 1. Further, if it is not in the above-mentioned rotation range, it is in the medium-speed rotation range N _{0 to} N _H , so the process returns to step 8 (step 31).

As described above, the turbocharger control device immediately generates power when the engine brake operates, regardless of the engine speed range.
The electric motor 17 operates as a generator to recover energy. Further, when the engine brake is returned to the inoperative state, a small turbocharger 1 and a large turbocharger 2 is rotation range the engine speed N at that time belongs i.e., the low-speed rotation range 0 to N _0, the medium-speed rotation region N ₀ It is controlled to be the operating state adapted to to N _H or high speed range N _H to N _MAX.

Alternatively, as another embodiment of this turbocharger control device, it can operate as follows.
The control of the turbocharger control device in this embodiment will be described with reference to FIGS. 5 and 9. FIG. 5 is a transient period when the turbocharger control device shown in FIG. 1 changes from a low speed rotation range to a medium speed rotation range, and is a schematic diagram showing another embodiment of the operating state at the time of switching from a small turbocharger to a large turbocharger. FIG. 9 is a structural diagram and FIG. 9 is a flowchart showing another embodiment of the operation at the time of switching from the small capacity turbocharger to the large capacity turbocharger in this turbocharger control device. In the diesel engine, in order to prevent the generation of smoke when switching from the small capacity turbocharger 1 to the large capacity turbocharger 2, by rotating the small capacity turbocharger 1 in the reverse direction, as shown by an arrow in FIG. Air is sent to the inlet side of the turbine 9 of the capacity turbocharger 2 and the exhaust gas is post-combusted to generate a large capacity turbocharger 2.
Smoke, carbon, soot, in the exhaust gases emitted from
Generation of particulates such as HC can be suppressed.

When performing this control, the turbocharger control device may be controlled by the controller 24 as follows. That is, the engine speed N is detected by the rotation sensor 22, the boost pressure BP is detected by the boost pressure sensor 21, and these detected values are input to the controller 24 (step 40). Controller 24
When the engine speed N is changing from the low speed rotation range ₀ to N ₀ to the medium speed rotation range N _{0 to NH} , the small capacity turbocharger 1 to the large capacity turbocharger respond to the detection signal. At the time of switching to the charger 2 (step 41), the large-capacity turbocharger 2 is started to operate until the rotational speed of the large-capacity turbocharger 2 or the boost pressure BP reaches a preset predetermined value BP ₀ . In this state, the compressor outlet valve 11 is closed to close the inlet side passage of the compressor 10 of the small capacity turbocharger 1, and the turbine inlet valve 5 and the turbine outlet valve 8 are opened to open the inlet side passage of the turbine 7. Then, the small-capacity turbocharger 1 is driven by the generator / motor 17 to rotate the small-capacity turbocharger 1 in the reverse direction (step 42), and the small-capacity turbocharger To backflow of air from the first turbine 7, performs control of sending the gas to the inlet passage side of the large-capacity turbocharger second turbine 9. At this time, if the turbine inlet valve 5 is configured as a check valve, even if the generator / motor 1
The electric power supplied to the turbine 7 is small and the turbine 7 to the turbine 9
Even if the force of feeding air into the turbine is reduced, it is possible to prevent the exhaust gas from flowing back to the turbine 7 side.

Accordingly, when this turbocharger control device is applied to a diesel engine, fresh air is introduced into the exhaust gas sent to the turbine 9 of the large capacity turbocharger 2, and smoke, carbon, soot, etc. in the exhaust gas are introduced.
It is possible to reburn particulates such as HC. In this case, since the outlet passage of the compressor 10 is closed, intake air does not flow back through the compressor 10 of the small capacity turbocharger 1. Therefore, from small capacity turbocharger 1 to large capacity turbocharger 2
After the transitional period of switching to
Of the engine speed or boost pressure BP is a preset value BP
_When it reaches ₀ (step 43), the occurrence of smoke and the like decreases, so immediately the generator / motor 17 of the small capacity turbocharger 2 is stopped, and the inlet side passage of the turbine 7 of the small capacity turbocharger 1, that is, If the turbine inlet valve 5 is closed (step 44) and only the operation of the large capacity turbocharger 2 is started, the energy consumption for preventing the generation of smoke can be minimized.

[0043]

Since the turbocharger control device according to the present invention is constructed as described above, it has the following effects. That is, this turbocharger control device
Since the small turbocharger is provided with the generator / motor, the generator / motor itself can be downsized, and the cost can be reduced.

Further, this turbocharger control device is
Since the small turbocharger is operated in the low speed rotation range and the generator / motor is operated by the electric motor, the boost pressure in the low speed rotation range can be sufficiently increased. Therefore, when the generator / motor is operated for a short time, for example, for one second when the vehicle starts, the boost pressure increases, and a predetermined boost can be secured.

Further, when the operation is switched from the small turbocharger to the large turbocharger, the generator / motor is operated by the electric motor, so that gas is sent to the large turbocharger by the operation of the electric motor. Along with this, the compressor of the large capacity turbocharger rotates even faster, so that the drop in boost pressure at the time of switching can be suppressed, and the occurrence of smoke can be reduced.

Further, since the generator / motor of the small turbocharger is operated as a generator in the high speed rotation range and engine braking, the overboost and engine braking force can be regenerated. Therefore, the thermal energy of the exhaust gas from the engine can be recovered as electric energy without being wasted, and the recovered electricity can be consumed for the next start or consumed by an auxiliary machine.

Further, in this turbocharger control device, at the time of switching from the small capacity turbocharger to the large capacity turbocharger, until the rotation speed or boost pressure of the large capacity turbocharger reaches a preset predetermined value, The large capacity turbocharger is operated, the compressor side passage of the small capacity turbocharger is closed and the turbine inlet side passage is opened, and the generator / motor of the small capacity turbocharger is operated by an electric motor to reversely rotate the small capacity turbocharger. When the gas is controlled to be fed from the turbine of the large capacity turbocharger to the turbine inlet side of the large capacity turbocharger, the exhaust gas exhausted from the large capacity turbocharger has particulates such as smoke, carbon, soot, and HC behind. Generation of smoke and the like is suppressed by burning.

[Brief description of drawings]

FIG. 1 is a schematic structural view showing an embodiment of a turbocharger control device according to the present invention, showing an operating state in a low speed rotation range.

FIG. 2 is a schematic diagram showing an embodiment of an operating state at the time of switching from a small turbocharger to a large turbocharger during a transient period when the turbocharger control device shown in FIG. 1 changes from a low speed rotation range to a medium speed rotation range. It is a structural drawing.

FIG. 3 is a schematic structural diagram showing an operating state in the medium speed rotation range of the turbocharger control device shown in FIG. 1, showing an operating state after switching.

FIG. 4 is a schematic structural diagram showing an operating state of the turbocharger control device shown in FIG. 1 in a high speed rotation range.

5 is a transient period in which the turbocharger control device shown in FIG. 1 changes from a low speed rotation range to a medium speed rotation range, and shows another embodiment of the operating state at the time of switching from the small turbocharger to the large turbocharger. It is a schematic structure drawing.

FIG. 6 is a configuration of a controller for performing operation switching control of a small turbocharger and a large turbocharger and switching control of a generator / motor in the turbocharger control device, and a mutual relationship between the controller and various detectors and various valves. It is a block diagram showing.

FIG. 7A is a flowchart showing a part of operation control of a small turbocharger and a large turbocharger in this turbocharger control device.

FIG. 7B is a flowchart showing the remaining part of the operation control of the small turbocharger and the large turbocharger in this turbocharger control device.

FIG. 8 is a flow chart showing control when the engine brake is activated in this turbocharger control device.

FIG. 9 is a flowchart showing another embodiment of the operation when switching from a small capacity turbocharger to a large capacity turbocharger in this turbocharger control device.

FIG. 10 is a graph showing a pressure ratio (boost pressure) of a compressor with respect to an air flow rate.

FIG. 11: Torque with respect to engine speed (BMEP)
It is a graph which shows.

FIG. 12 is a graph showing a pressure ratio with respect to an air flow rate.

FIG. 13 is a graph showing a boost pressure increase rate with respect to an elapsed time from the start of operation of a turbocharger.

FIG. 14 is a graph showing the power generation capacity with respect to the flow rate of exhaust gas.

FIG. 15 is a schematic sectional view showing a conventional turbocharger.

FIG. 16 is a schematic structural diagram showing a conventional turbocharger device.

FIG. 17 is a schematic sectional view showing a conventional turbocharger with a generator / motor.

[Explanation of symbols]

1 Small turbocharger 2 Large turbocharger 5,6 Switching valve 7,9 Turbine 8 Turbine outlet valve 10,13 Compressor 11,15 Compressor outlet valve 17 Generator / motor 20 Accelerator sensor (engine brake sensor) 21 Boost pressure sensor 22 Rotation sensor

Claims (6)

[Claims] 1. A small capacity turbocharger including a turbine, a compressor and a generator / motor, a large capacity turbocharger including a turbine and a compressor, a rotation sensor for detecting an engine speed, and an engine rotation detected by the rotation sensor. The engine is controlled so as to operate the small capacity turbocharger in response to a low speed range in which the number of revolutions is less than or equal to a preset rotational speed, and to operate the large capacity turbocharger in response to a speed in which the number exceeds the low speed range. A turbocharger control device, comprising: a controller for switching the electric power generator / motor according to the number of revolutions to switch between an operating state of the electric motor operation or an operating state of the generator operation. 2. The turbocharger control device according to claim 1, wherein the controller controls to operate the generator / motor as an electric motor in response to at least a low engine speed range. 3. The turbocharger control device according to claim 1, wherein the controller controls to operate the generator / motor as a generator in response to at least a high engine speed range. 4. The turbocharger control device according to claim 1, wherein the controller controls the generator / motor to operate as a generator when the engine brake is activated. 5. The controller rotates the large capacity turbocharger when switching from the small capacity turbocharger to the large capacity turbocharger in response to a change in engine speed from the low speed range to the medium speed range. Until the number or boost pressure reaches a preset predetermined value, the generator / motor of the small capacity turbocharger is operated as an electric motor, and control is performed to send gas from the small capacity turbocharger to the large capacity turbocharger. The turbocharger controller according to claim 1, wherein the turbocharger controller is a turbocharger controller. 6. The controller controls the rotational speed of the large capacity turbocharger when switching from the small capacity turbocharger to the large capacity turbocharger in response to a change in engine speed from a low speed range to a medium speed range. Or, until the boost pressure reaches a preset predetermined value, the large capacity turbocharger is operated, the compressor side passage of the small capacity turbocharger is closed and the turbine inlet side passage is opened, and the small capacity turbocharger is opened. Power generation
The turbocharger control device according to claim 1, wherein control is performed to feed gas from a turbine of the small capacity turbocharger to a turbine inlet side of the large capacity turbocharger by operating the electric motor to rotate in a reverse direction.