JP3473522B2 - Variable nozzle turbocharger control device for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a turbocharger used as a supercharging system for an internal combustion engine,
More specifically, the present invention relates to a variable nozzle turbocharger control device for an internal combustion engine that includes a variable nozzle for varying the flow rate of exhaust gas blown to a turbine wheel.

[0002]

2. Description of the Related Art Generally, in an internal combustion engine for an automobile,
In order to improve the output, it is preferable to increase the amount of air filled in the combustion chamber. Therefore, conventionally, not only is air sent to the combustion chamber by the negative pressure generated in the combustion chamber with the movement of the piston, but also that air is forcibly sent to the combustion chamber to increase the efficiency of filling the combustion chamber with air. A supercharging system has been proposed and put into practical use. As such a supercharging system, for example, a variable capacity type turbocharger described in JP-A-11-125120 is known.

The turbocharger described in this publication is
A turbo wheel that is rotated by the exhaust gas flowing through the exhaust passage of the internal combustion engine and a compressor wheel that forcibly sends the air in the intake passage of the internal combustion engine to the combustion chamber side. The turbine wheel and the compressor wheel are integrally rotatably connected via a rotor shaft. Then, when the exhaust gas is blown to the turbine wheel to rotate the wheel, the rotation is transmitted to the compressor wheel via the rotor shaft. By rotating the compressor wheel in this way, the air in the intake passage is forcibly fed into the combustion chamber.

Further, in the conventional turbocharger described above, an exhaust gas path is formed so as to surround the outer circumference of the turbine wheel along the rotational direction of the wheel.
The exhaust gas passes through the exhaust gas passage and is blown toward the axis of the turbine wheel. A variable nozzle for varying the flow velocity of the exhaust gas blown to the turbine wheel is provided in the exhaust gas passage. This variable nozzle includes a plurality of nozzle vanes and an actuator for opening and closing these nozzle vanes.
The nozzle vanes are located at equal angles around the axis of the turbine wheel and are opened and closed by the actuators in synchronization with each other.

The flow velocity of the exhaust gas blown to the turbine wheel is adjusted by opening and closing each nozzle vane synchronously and changing the size of the gap between the adjacent nozzle vanes. By adjusting the flow rate of the exhaust gas by opening and closing the nozzle vanes in this way, the rotational speed of the turbine wheel is adjusted, and thus the amount of air forcedly fed into the combustion chamber is adjusted.

[0006]

By the way, in the above conventional turbocharger, for example, a stepping motor is used as an actuator, and each nozzle vane is opened and closed by the stepping motor.
To accurately control the opening / closing position of each nozzle vane, it is necessary to accurately set the initial position of each nozzle vane.For this reason, each nozzle vane is opened / closed to the fully closed position or the fully opened position until the stepping motor is out of step, The fully closed position or the fully open position is set as the initial position.

However, opening and closing each nozzle vane to the fully closed position or the fully opened position without considering the state of the internal combustion engine causes various problems. For example, the fully closed position of each nozzle vane is set extremely close to the throttle side in order to ensure the effectiveness of the heater when the internal combustion engine is operating at low speed and has a light load (for example, when it is idle). In other words, in order to secure the effectiveness of the heater that uses the heat of the internal combustion engine, it is necessary to throttle each nozzle vane to increase the back pressure of the internal combustion engine (exhaust gas is difficult to be discharged) and increase the internal loss of the internal combustion engine. Because there is
The fully closed position of each nozzle vane is set extremely close to the throttle side. Therefore, during normal operation, an abnormality occurs in the turbocharger, and when each nozzle vane is closed to the fully closed position in order to reset the initial position of each nozzle vane, the back pressure of the internal combustion engine becomes too high and the internal combustion engine There was a problem that the power performance of the vehicle deteriorated and that black smoke was mixed with the exhaust gas.

Further, when the fully open position of each nozzle vane is set as the initial position when the internal combustion engine is cold started, the accuracy of the position control of each nozzle vane near the fully open position is improved, while in the vicinity of the fully closed position. The accuracy of position control is reduced. Therefore, at the time of starting the internal combustion engine that opens and closes each nozzle vane in the vicinity of the fully closed position, the back pressure of the internal combustion engine becomes unstable and the effectiveness of the heater varies.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and avoids the occurrence of various problems,
An object of the present invention is to provide a variable nozzle turbocharger control device for an internal combustion engine, which is capable of initializing the opening / closing position of each nozzle vane of the variable nozzle.

[0010]

[0011]

[0012]

[Means for Solving the Problems ] To solve the above problems
In the present invention, a variable nozzle turbocharger control device for an internal combustion engine, wherein a variable nozzle is provided in a path of exhaust gas blown to a turbine wheel, and the flow velocity of the exhaust gas is adjusted by opening and closing the variable nozzle by an actuator, When the internal combustion engine is cold started, the actuator is operated until the variable nozzle is fully closed, and the fully closed position is set as an initial position of the variable nozzle.

According to the present invention, when the internal combustion engine is cold started, the fully closed position of the variable nozzle is set as the initial position of the variable nozzle. In this case, the accuracy of position control of each nozzle vane near the fully closed position is improved. Therefore, when the heater is required in the cold, it is possible to suppress variations in the effectiveness of the heater.

Further, according to the present invention, a variable nozzle turbocharger control of an internal combustion engine is provided in which a variable nozzle is provided in a path of exhaust gas blown to a turbine wheel, and the variable nozzle is opened and closed by an actuator to adjust the flow rate of the exhaust gas. In the apparatus, a heater that uses the heat of the internal combustion engine, and when the heater is operating and is idle, the actuator is operated until the variable nozzle is fully closed, and the fully closed position is set to the initial position of the variable nozzle. And a control means for setting the position.

According to the present invention, the fully closed position of the variable nozzle is set as the initial position of the variable nozzle when the heater is operating and when the heater is idle. Also in this case, the accuracy of position control of each nozzle vane near the fully closed position is improved, so that the effectiveness of the heater is stabilized.

In one embodiment, the control means operates the actuator until the variable nozzle is fully opened when the internal combustion engine is operating at high rotation speed and low load, and the fully opened position is set to the initial position of the variable nozzle. Has been set as. In this way, when the internal combustion engine is operating at high rotation speed and low load, if the fully open position of the variable nozzle is set as the initial position of the variable nozzle, the position control accuracy of each nozzle vane near the fully open position is improved. In addition, the controllability in the low load operation state is improved.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 schematically shows an embodiment of the variable nozzle turbocharger control device of the present invention. As shown in FIG. 1, the turbocharger 11 includes a center housing 12, a compressor housing 13, and a turbine housing 14. Center housing 12
The rotor shaft 15 is rotatably supported by the rotor shaft 15 around its axis L. A compressor wheel 16 having a plurality of blades 16a is attached to one end (the left end in the figure) of the rotor shaft 15. A turbine wheel 17 including a plurality of blades 17a is attached to the other end (right end in the figure) of the rotor shaft 15.

On one end side of the center housing 12, the compressor housing 13 is formed so as to surround the outer circumference of the compressor wheel 16 and extend in a spiral shape.
Is attached. In such a compressor housing 13, an intake inlet 13a into which air supplied to the combustion chamber of the engine (internal combustion engine) 10 is introduced is provided in a portion located on the opposite side of the center housing 12. Further, inside the compressor housing 13, a compressor passage 18 is provided which extends in a spiral shape like the housing 13 and communicates with the combustion chamber. Further, the compressor housing 13 is provided with a delivery passage 19 for delivering the air introduced into the housing 13 via the intake inlet 13a to the compressor passage 18. The delivery passage 19 is provided along the compressor passage 18. Then, when the compressor wheel 16 rotates around the axis L based on the rotation of the rotor shaft 15, air is introduced into the intake inlet 13a and the delivery passage 1
9 and the compressor passage 18 are forced into the combustion chamber.

The turbine housing 14 is attached to the other end of the center housing 12 so as to surround the outer periphery of the turbine wheel 17 and extend in a spiral shape. A scroll passage 20 extending in a spiral shape is provided in the turbine housing 14 as in the housing 14. The scroll passage 20 communicates with the exhaust passage of the engine 10, and exhaust gas from the combustion chamber is sent through the exhaust passage.

In the turbine housing 14, the exhaust gas in the scroll passage 20 is supplied to the turbine wheel 17.
An exhaust gas passage 23 for spraying toward is provided along the scroll passage 20. By blowing the exhaust gas from the exhaust gas passage 23 to the turbine wheel 17, the turbine wheel 17 rotates about the axis L. The exhaust gas after being blown to the turbine wheel 17 is the turbine housing 14
In the above, it is sent to a catalyst (not shown) through an exhaust outlet 14a provided in a portion located on the side opposite to the center housing 12.

Next, the exhaust gas passage 23 is provided between the center housing 12 and the turbine housing 14.
The variable nozzle 31 for adjusting the flow velocity of the exhaust gas blown to the turbine wheel 17 via the
This will be described with reference to (a) and (b). 2A is a front view of the variable nozzle 31, and FIG. 2B is a sectional view of the variable nozzle 31.

As shown in FIGS. 2A and 2B, the variable nozzle 31 includes a nozzle back plate 32 formed in a ring shape. The nozzle back plate 32 is provided with a plurality of shafts 33 at equal angles centered on the circle center of the plate 32. Each shaft 33 is rotatably supported by penetrating the nozzle back plate 32 in its thickness direction. A nozzle vane 34 is fixed to one end of each of the shafts 33. An opening / closing lever 35 that is orthogonal to the shaft 33 and extends to the outer edge of the nozzle back plate 32 is fixed to the other end of the shaft 33. Open / close lever 3
A pair of nipping portions 35a that are bifurcated are provided at the tip of the pin 5.

An annular ring plate 36 is provided between each opening / closing lever 35 and the nozzle back plate 32 so as to overlap with the nozzle back plate 32. The ring plate 36 is rotatable in the circumferential direction around its center. Further, the ring plate 36 is provided with a plurality of pins 37 at equal angles centered on the center of the circle, and the pins 37 sandwich the pinching portions 35 of the opening / closing levers 35.
It is sandwiched between a and rotatably.

When the ring plate 36 is rotated about its center, each pin 37 pushes the holding portion 35a of each opening / closing lever 35 in the rotation direction of the ring plate 36.
As a result, the opening / closing levers 35 rotate the shaft 33, and as the shaft 33 rotates, the nozzle vanes 34 open / close in a synchronized state about the shaft 33.
The size of the gap between the adjacent nozzle vanes 34 changes based on the synchronized opening / closing operation of the nozzle vanes 34.

As shown in FIG. 1, the variable nozzle 31 having the above-described structure includes the center housing 12 and the turbine housing 1.
4, and is fixed by being sandwiched between the housings 12 and 14. In this state, the surfaces of the nozzle back plate 32 and the turbine housing 14 that face each other extend in the direction orthogonal to the axis L to form the inner side surfaces 23a and 23b of the exhaust gas passage 23. Further, the outer edge of the ring plate 36 (the lower end in the figure)
Is provided with a pin 46 extending in the same direction as the axis L, and the drive mechanism 4 for driving the variable nozzle 31 is provided on the pin 46.
Two are connected.

The drive mechanism 42 is provided with a support shaft 43 rotatably supported in the center housing 12 while extending in the same direction as the pin 46. A drive lever 44 rotatably connected to a pin 46 is fixed to one end (right end in the figure) of the support shaft 43. An operation piece 45 connected to the stepping motor 51 is fixed to the other end portion (left end portion in the figure) of the support shaft 43.

When the operation piece 45 is operated by driving the stepping motor 51 to rotate the support shaft 43, the drive lever 44 rotates about the support shaft 43 as the support shaft 43 rotates. As a result, the ring plate 36 is pushed in the circumferential direction by the drive lever 44 via the pin 46 and is rotated about the axis L. By the rotation of the ring plate 36, the size of the gap between the adjacent nozzle vanes 34 is adjusted, and the scroll passage 20 is adjusted based on the adjustment of the gap.
The flow velocity of the exhaust gas blown from the turbine to the turbine wheel 17 via the exhaust gas passage 23 is adjusted.

The ECU 100 inputs the detection outputs of various sensors provided in the engine 10, identifies the operating state of the engine 10 on the basis of these detection outputs, and drives and controls the stepping motor 51, thereby varying the operating state. Each nozzle vane 34 of the nozzle 31 is opened and closed to adjust the flow velocity of the exhaust gas blown to the turbine wheel 17. By adjusting the flow rate of the exhaust gas, the rotation speeds of the turbine wheel 17, the rotor shaft 15, and the compressor wheel 16 are adjusted appropriately, and by extension, the amount of air forcedly sent to the combustion is adjusted. By adjusting the amount of intake air to the combustion chamber, the engine 1
It is possible to achieve both improvement in output of 0 and prevention of excessive pressure in the combustion chamber.

On the other hand, a radiator 71 is connected to the engine 10 so that the cooling water for the engine 10 is supplied to the radiator 7.
1 is circulated and cooled. Further, like the radiator 71, a heater 72 is also connected to the engine 10, and the cooling water heated by the heat generation of the engine 10 is circulated to the heater 72 to heat the heater 72. Hot air is blown into the room.

Now, in such a configuration, since each nozzle vane 34 of the variable nozzle 31 is opened / closed by the stepping motor 51, each nozzle vane 34 is opened / closed to the fully closed position or the fully opened position, and the fully closed position or If the fully open position is not set as the initial position, the opening / closing control of each nozzle vane 34 cannot be accurately performed. Further, as described above, if each nozzle vane 34 is set to the fully closed position or the fully open position without considering the state of the engine 10, various problems occur. Therefore, the ECU 100 sets the initial position of each nozzle vane 34 according to the flowchart shown in FIG. 3, thereby avoiding various problems.

First, the ECU 100 determines the engine 10 based on the detection outputs of various sensors provided in the engine 10.
It is determined whether or not is at the start (step 101).
For example, if the starter motor of the engine 10 is on,
And if the rotation speed of the engine 10 is equal to or lower than the predetermined rotation speed,
It is determined that the engine 10 is starting. Engine 10
If the engine is starting (step 101, Yes), the ECU
100 determines whether the engine is cold starting or warm starting based on the intake air temperature of the engine 10 and the temperature of the cooling water (step 102). If it is a cold start, the ECU 100
Driving the stepping motor 51 in one direction closes each nozzle vane 34 until each nozzle vane 34 of the variable nozzle 31 hits the fully closed position, and further operates the stepping motor 51 with each nozzle vane 34 hit the fully closed position. The stepping motor 51 is stepped out by driving in the same direction, and then the stepping motor 51 is stopped.
The rotation position of 1 (fully closed position) is set as the initial position (step 103). If it is a warm start, the ECU
100 drives each stepping motor 51 in the reverse direction to open each nozzle vane 34 until each nozzle vane 34 of the variable nozzle 31 hits the fully opened position, and further drives the stepping motor 51 in the same direction to remove the stepping motor 51. After the adjustment, the stepping motor 51 is stopped, and the rotational position (fully open position) of the stepping motor 51 at this time is set as the initial position (step 104).

In this way, at the time of cold start, the variable nozzle 31
If each nozzle vane 34 is moved to the fully closed position and the turning position (fully closed position) of the stepping motor 51 is set as the initial position, the accuracy of position control of each nozzle vane 34 near the fully closed position is improved. . Therefore, the back pressure of the engine 10 is stabilized and the effectiveness of the heater 72 is stabilized.

The fully closed position of each nozzle vane 34 may be set as the initial position at the time of warm start. In short, at the time of starting the engine 10, the nozzle vanes 34 are irrespective of whether they are cold starting or warm starting.
Set the fully closed position of as the initial position. When the outside air temperature is low, it is necessary to stabilize the effectiveness of the heater 72 even during a warm start. Therefore, the initial position of each nozzle vane 34 is set to the fully closed position, and each nozzle vane near the fully closed position is set. It is preferable to improve the accuracy of the position control of 34.

Next, if the engine 10 is not started (step 101, No), the ECU 100 determines whether the engine 10 is in a high rotation and light load operating state (step 105). For example, when the rotation speed of the engine 10 is equal to or higher than a predetermined rotation speed and a throttle valve (not shown) of the engine 10 is equal to or lower than a predetermined opening degree,
It is determined that the engine is operating at high rotation speed and light load. Here, if the engine 10 is in the operating state of high rotation and light load (step 105, Yes), the ECU 100 drives the stepping motor 51 to open each nozzle vane 34 until it hits the fully open position, and further the stepping motor 51. Of the stepping motor 51 is stopped by continuing the driving of the stepping motor 51, and then the stepping motor 51 is stopped.
The rotation position (full open position) of is set as the initial position (step 106).

As described above, at the time of high rotation and light load, each nozzle vane 34 of the variable nozzle 31 is moved to the fully open position,
If this fully open position is set as the initial position, the accuracy of position control of each nozzle vane 34 near the fully open position is improved, and thus the controllability in a high rotation and low load operation state is improved.

Next, if the engine 10 is not in the operating state of high rotation and light load (step 105, No), the ECU
100 determines whether the heater 72 is turned on (step 107) and whether the engine 10 is in a stable idle state (step 108). For example, a flag indicating ON / OFF of the heater 72 is set in advance, and the heater 7 can be detected by observing this flag.
It is determined whether 2 is turned on. Further, it is determined whether or not the engine 10 is in a stable idle state based on whether or not the engine 10 is rotating at an idle speed for a certain period or longer. Here, if the heater 72 is turned on (step 107, Yes) and the engine 10 is in a stable idle state (step 108, Yes).
s), the ECU 100 closes each nozzle vane 34 by driving the stepping motor 51 until it abuts the fully closed position, and further continues driving of the stepping motor 51 to step out the stepping motor 51, and then the stepping motor 51. Is stopped, and the rotational position (fully closed position) of the stepping motor 51 at this time is set as the initial position (step 109).

As described above, when the heater 72 is turned on and the engine 10 is in a stable idle state, the fully closed position of each nozzle vane 34 of the variable nozzle 31 is set as the initial position, and therefore, in the vicinity of the fully closed position. The accuracy of position control of each nozzle vane 34 is improved. Therefore, the back pressure of the engine 10 during idling is stabilized, and the effectiveness of the heater 72 is stabilized.

Next, if the heater 72 is not on (step 107, No) or the engine 10 is not in a stable idle state (step 108, No), the ECU
100 determines whether or not an abnormality has occurred in this variable nozzle turbocharger control device (step 11).
0). For example, in the normal opening / closing control of each nozzle vane 34, when the stepping motor 51 is out of step carelessly, it is considered that an abnormality has occurred. If the ECU 100 determines that an abnormality has occurred (step 110, Yes), the stepping motor 51 is driven to open each nozzle vane 34 until it abuts the fully open position, and the stepping motor 51 is de-stepped. Stop the stepping motor 5 at this time
The rotation position of 1 (full open position) is set as the initial position (step 111).

In this way, when an abnormality occurs, the variable nozzle 31
If each of the nozzle vanes 34 is moved to the fully open position and this fully open position is set as the initial position, the back pressure of the internal combustion engine will not suddenly increase, the power performance of the internal combustion engine will deteriorate, and No black smoke is mixed in.

As described above, according to the present embodiment, during cold start, at high rotation and light load, when the heater 72 is turned on and the engine 10 is in a stable idle state, and when there is an abnormality, respectively. Then, either the fully open position or the fully closed position of each nozzle vane 34 is selectively set as the initial position, which causes various problems, that is, variations in the effectiveness of the heater 72 during cold start, high rotation and low load operation. Deterioration in controllability, heater 72 when heater 72 is turned on and engine 10 is in a stable idle state
It is possible to set the initial position of each nozzle vane 34 while avoiding the variation of the effect of the above, the deterioration of the power performance of the internal combustion engine at the time of the occurrence of an abnormality, the mixing of black smoke with the exhaust gas, and the like.

In this embodiment, each step 101,
Although either the fully closed position or the fully open position is set as the initial position according to the result of the determination of 102, 105, 107, 110, the process corresponding to these determination and the result thereof is appropriately selected. Just do it. Further, in the present embodiment, the open loop control of the stepping motor 51 is performed. However, an encoder that detects the rotation angle of the stepping motor 51 is provided, and the stepping motor 51 is rotated to the target angle based on the detection output of this encoder. You may perform the closed loop control which makes it do.

[0043]

[0044]

As described above , according to the present invention, when the internal combustion engine is cold started, the fully closed position of the variable nozzle is set as the initial position of the variable nozzle. In this case, the accuracy of position control of each nozzle vane near the fully closed position is improved. Therefore, at the time of starting the internal combustion engine that opens and closes each nozzle vane near the fully closed position, the back pressure of the internal combustion engine is stabilized and the effectiveness of the heater is stabilized.

Further, according to the present invention, the fully closed position of the variable nozzle is set as the initial position of the variable nozzle when the heater is operating or when the internal combustion engine is idle. Also in this case, the accuracy of position control of each nozzle vane near the fully closed position is improved, so that the effectiveness of the heater is stabilized.

Further, since the fully open position of the variable nozzle is set as the initial position of the variable nozzle when the internal combustion engine is operating at high rotation speed and low load, the accuracy of the position control of each nozzle vane near the fully open position is improved. The controllability under high rotation and low load operation is improved.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an embodiment of a variable nozzle turbocharger control device of the present invention.

2A is a front view of a variable nozzle in the apparatus of FIG. 1, and FIG. 2B is a sectional view of the variable nozzle.

FIG. 3 is a flowchart showing a process in the apparatus of FIG.

[Explanation of symbols]

10 engine 11 turbocharger 16 compressor wheels 17 turbine wheel 31 variable nozzle 34 nozzle vanes 51 stepping motor 71 radiator 72 heater 100 ECU

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02B 37/24 F02B 37/12 302

Claims (3)

(57) [Claims] 1. A variable nozzle turbocharger control device for an internal combustion engine, wherein a variable nozzle is provided in a path of exhaust gas blown to a turbine wheel, and the variable nozzle is opened and closed by an actuator to adjust the flow velocity of the exhaust gas. When the internal combustion engine is cold started, the variable nozzle is fully closed.
The actuator is operated until
Variable nozzle turbocharger control system for an internal combustion engine and a control means for setting a position as an initial position of the variable nozzle. 2. A variable nozzle turbocharger control device for an internal combustion engine, wherein a variable nozzle is provided in a path of exhaust gas blown to a turbine wheel, and the variable nozzle is opened and closed by an actuator to adjust a flow velocity of the exhaust gas. A heater that uses the heat of the internal combustion engine and an idle of the internal combustion engine when the heater is operating.
The case, the variable nozzle actuates the actuator until fully closed, the variable nozzle turbocharger control system for an internal combustion engine and a control means for setting the fully closed position as the initial position of the variable nozzle. 3. The high speed rotation of the internal combustion engine is controlled by the control means.
And during low load operation, until the variable nozzle is fully opened.
Operate the actuator to move the fully open position to the
The variable nozzle is set as an initial position according to claim 1 or 2.
A variable nozzle turbocharger control device for an internal combustion engine as described .