JPH1077856A - Control device for variable displacement turbo charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a variable turbo charger to improve acceleration performance during transition. SOLUTION: A throttle 4 is arranged at the operation pressure input route 19 of an actuator 1 opened and closed by a moving vane 16 and application of a working pressure is delayed, and a supercharge pressure is sufficiently increased during transition. During cold down, a throttle amount of a throttle 4 is increased compared with a warming-up period and acceleration property and a warming-up property are improved. During rapid closing of an accelerator after acceleration, a throttle amount of a throttle 4 is temporarily reduced and by temporary suppression of the increase of a supercharge pressure, the occurrence of surging is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement turbocharger control device that changes the opening of a variable nozzle (variable nozzle: VN) by opening and closing a movable vane.

[0002]

2. Description of the Related Art As disclosed in Japanese Patent Application Laid-Open No. 63-227926, in a variable capacity turbocharger, a movable vane is opened and closed by an actuator and an operating pressure supplied to an actuator working chamber (for example, a compressor outlet). Pressure, etc.), the opening and closing of the movable vanes is controlled. Conventionally, movable vanes detect engine operating conditions (engine speed x engine load) with sensors,
A two-dimensional map (engine speed × engine load) of whether the movable vane should be opened or closed at that time is prepared and stored in advance, and the engine rotational speed × engine load without taking into account the transient state of engine operation. Opening and closing are controlled based on a map created for a steady state.

[0003]

However, in the conventional open / close control of the movable vane of the variable displacement turbocharger, satisfactory control is performed in a steady operation state of the engine, but there are the following problems in a transient operation state of the engine. . That is, in the unsteady state of the engine operation, even if the movable vane is opened and closed based on the two-dimensional map of the engine speed × the engine load prepared based on the steady state, the opening and closing of the movable vane deviate from the intended opening and closing, and a sufficient excess There is a problem that the supply pressure increases and acceleration performance cannot be obtained. For example, during a transition of the operating state of the engine (for example, at the time of starting the engine), the gas temperature at the inlet of the turbine is significantly different from the steady state, and at a certain engine speed × engine load, for example, 600 ° C. in the steady state When the engine is started, the temperature is only 400 ° C., for example. In that case, the exhaust energy is naturally reduced in the transient state as compared with the steady state, so that the turbine speed is also low, and the supercharging pressure is also low,
The acceleration performance is not enough. If the engine speed and the engine load rise to a certain value even though sufficient acceleration has not been obtained, the movable vane opens earlier, resulting in insufficient acceleration during transition. An object of the present invention is to provide a control device for a variable displacement turbocharger capable of obtaining a sufficient acceleration performance even in a transient state.

[0004]

The present invention to achieve the above object is as follows. (1) The applied pressure applied to the actuator that drives the movable vane to open and close is operated for a predetermined time to keep the movable vane closed. Specifically, a throttle is provided in the pressure path applied to the actuator. (2) The diaphragm is a movable diaphragm. (3) The throttle amount of the variable throttle is larger when the engine is cold than when it is warm. (4) The throttle amount of the variable throttle is temporarily reduced during the surging possible period, and the movable vane is temporarily opened. (5) Instead of the throttle, the pressure of the working pressure source may be temporarily reduced during engine operation transition.

In the above (1) to (4), since the throttle is provided, even if the engine operating condition becomes a specific condition of moving the movable vane from the closed state to the open state during the transition, the application of the pressure to the actuator is delayed, Opening of the movable vane is delayed. As a result, the closed state of the movable vane is maintained for a predetermined period of time when the exhaust gas temperature is not sufficiently increased during a transition period, so that the supercharging pressure is sufficiently increased, and sufficient acceleration performance is obtained during the transition period. In the above (3), since the throttle amount is larger in the cold state than in the warm state, the acceleration performance in the cold state and the warm-up property can be improved. Diesel vehicles generally have a slower rise in exhaust gas temperature than gasoline engine vehicles and have poor warm-up properties. Therefore, in addition to improving the acceleration performance by the throttle during warming, the amount of throttle is increased during cold and the opening of the movable vane is delayed from that during warm, so that the supercharging pressure further increases during cold, The time during which the engine load is increased also increases, so that the acceleration performance in cold weather and the warm-up property can be improved. In the above (4), since the movable vane is temporarily opened (the throttle amount is small), surging of the compressor can be avoided. At the time of sudden closing of the accelerator after acceleration, the compressor outlet pressure rises, the surging phenomenon of the compressor tends to occur for a predetermined period due to the decrease in air flow rate, but during that period, the movable vane is opened and the turbine gas pressure is reduced,
The turbine rotation is suppressed, the compressor outlet pressure is reduced, and the occurrence of surging is suppressed. In the above (5),
By temporarily weakening the pressure of the operating pressure source of the actuator during transition instead of the throttle (lower the positive pressure for positive pressure and lowering the negative pressure for negative pressure), the same operation and effect as the throttle can be achieved. You may do so because it is obtained.

[0006]

FIG. 1 shows a main part of the apparatus of the present invention, and FIG. 2 shows the operation of the apparatus of the present invention with respect to a conventional apparatus.
FIG. 3 shows the control of the device of the present invention, and FIG. 4 shows the general system of a turbocharger.
First, the general configuration will be described. As shown in FIG. 4, the turbocharger 10 includes a turbine 11 and a compressor 12 driven by the turbine 11. The turbine 11 is disposed in an exhaust passage 14 of an internal combustion engine (diesel engine or gasoline engine) 13 and emits exhaust energy. (The speed and temperature of the exhaust gas).
Numeral 2 is rotationally driven by a turbine 11 and arranged in an intake passage 15 of an internal combustion engine 13 to compress intake air and supercharge the internal combustion engine. As a result, the amount of air to the internal combustion engine is increased, the torque and output of the internal combustion engine are increased, and the acceleration is significantly improved.

A movable vane 16 that rotates and changes the opening degree and thereby changes the nozzle area is disposed in a turbine nozzle portion that blows high-speed, high-temperature engine exhaust gas to the blades of the turbine 11. By opening and closing the vanes 16, the flow rate of the exhaust gas acting on the turbine 11 is controlled, and the capacity of the turbocharger 10 is made variable.

A plurality of movable vanes 16 are provided. The shaft of each movable vane 16 extends through the wall of the turbine housing, extends outside the housing, and is connected to a single unison ring 17. The unison ring 17 is shown in FIG. As described above, the entire movable vane 16 is rotated by the actuator 1.
Are simultaneously opened and closed. Actuator 1
Has a working chamber into which working pressure from a working pressure source 2 (supercharging pressure at the compressor outlet pressure or negative pressure from the vacuum pump) is led. When the operating pressure is turned on to the actuator working chamber, the unison ring 17 rotates the movable vane 16 to the open side, and when the operating pressure is turned off, the unison ring 17 closes the movable vane 16 by a spring 18 built into the actuator 1. Rotate to the side.

As shown in FIG. 1, for turning on and off the working pressure to the working chamber, a valve which is also used as the throttle 4 is provided in a working pressure input path 19 which connects the working pressure source 2 and the actuator 1, and this valve is provided. 4 for C of the engine control computer
This is performed by opening and closing in response to an output signal of a PU (Central Processor Unit) 3. The CPU 3 receives an engine speed signal (NE) 5 and an engine load signal (θ) 6.

Next, the configuration and operation of the present invention for improving the acceleration during transition will be described. In the present invention, as shown in FIG. 1, in order to delay the application of the working pressure of the working pressure source 2 to the working chamber of the actuator 1, a working pressure input path 19 connecting the working pressure source 2 and the actuator 1. Aperture 4 is provided. The throttle 4 may be provided separately from a valve for turning on and off the application of the operating pressure, or as shown in FIG. 1, may be used also as a valve for turning on and off the application of the operating pressure. The open state of the valve needs to be narrower than the conventional open state of the simple on / off valve.

The stop 4 is preferably a variable stop whose stop amount is variable. In particular, when performing fine variable displacement control as shown in FIG. 3, the diaphragm 4 must be a variable diaphragm. In the case where the throttle 4 is also used as a valve, in order to make the throttle amount variable when the valve is in the open state, a duty-controlled vacuum switching valve or an electric vacuum regulating valve may be used.
Alternatively, the aperture may be variable mechanically, in which case a heat-sensitive aperture such as bimetal may be used.

The operation will be described with reference to FIG. Conventional
As shown by the solid line in FIG.
2 of engine speed x engine load without considering passing
Specified by a dimensional map. Therefore, the boost pressure
P_BEngine speed NE is specified even if
Rotation speed NE ₁Is reached, the movable vane 16 moves to the opening operation.
As a result, sufficient boost pressure and acceleration performance could not be obtained.

On the other hand, in the present invention, since the throttle 4 is provided, as shown by a broken line in FIG.
Even if E becomes a specific condition for moving the movable vane 16 from the closed state to the open state, the application of the pressure to the actuator 1 is delayed due to the presence of the throttle 4, and the opening of the movable vane 16 is delayed. Thus, during the transient, when the exhaust temperature is not raised sufficiently, the closed state of the movable vane 16 is continued a predetermined time, supercharging pressure P _B is sufficiently be increased (e.g., to go stand up to the set pressure ), And sufficient acceleration performance can be obtained during transition. The hatched area in FIG. 2 is a part where the boost pressure is improved.

FIG. 3 shows the structure and operation of the diesel engine according to the present invention for improving the warm-up property during cold operation and the acceleration property during transition, and for avoiding compressor surging when the accelerator is suddenly closed after acceleration. This will be described with reference to FIG. In a diesel engine, the throttle amount of the variable throttle 4 is temporarily increased when the engine is cold compared to when it is warm. In addition, when the accelerator is rapidly closed after the acceleration of the engine, the throttle amount of the variable throttle 4 is temporarily reduced during the surging possible period, and the movable vane 16 is temporarily opened. In addition, a water temperature signal 8 and a supercharging pressure signal P _B 7 from a water temperature sensor are also input to the CPU 3 in order to perform the above detailed control. The CPU 3 is configured to control the aperture amount of the aperture 4.

FIG. 3 shows a control routine for controlling the throttle amount and controlling the opening and closing of the movable vanes, which are executed by the CPU 3. This routine is interrupted at regular time intervals during transition. In step 101, it is determined whether the engine load is in an acceleration state or a deceleration state. If the vehicle is accelerating, the process proceeds to step 102. If the vehicle is decelerating, the process proceeds to step 106.

If the engine is in the accelerated state, the engine speed NE is increased to a predetermined speed NE * (full engine load /
Is determined to be less than or equal to a value allowable for durability), and NE <N
If it is not E *, the process proceeds to step 109 to prevent the engine from being broken, and the amount of throttle 4 is minimized so that the movable vane 16 can be opened immediately. If the movable vane 16 is opened during the transition, the turbine speed decreases and the boost pressure hardly increases.

If NE <NE * in step 102, the routine proceeds to step 103, where the engine coolant temperature T _W is set to a predetermined value T _W *.
It is determined whether or not the value is greater than (a value allowable for durability at low temperatures). If T _W > T _W *, the engine is considered to be in a warm state, and the routine proceeds to step 105. In step 105, the supercharging pressure P _B it is determined whether a predetermined value P _B * (acceptable value full engine load and durability on) or less, if not * P _B <P _B, to prevent engine breakdown To step 109,
The movable vane 16 is set to the open side with the aperture amount of the aperture 4 minimized. In step 105, if * P _B <P _B, the process proceeds to step 108, so as to maintain the closed state of the movable vanes 16 to maximize the aperture of the diaphragm 4. Step 10
Routes 1, 102, 103, 105, and 108 are route 1
9 corresponds to a control for delaying the opening of the movable vane 16 at the time of a transition by inserting the throttle 4 into 9.

If T _W > T _W * is not satisfied in step 103, the engine is in a cold state, and the routine proceeds to step 104. In step 104, the supercharging pressure P _B is set to a predetermined value P _B *.
A certain value P (a value allowed for the engine full load and durability)
₀ added value P _B * + small whether determined from P _0, P _B
If <P _B * + P ₀ , the routine proceeds to step 108, where the amount of aperture of the aperture 4 is maximized, and the movable vane 16 is kept closed. Step 104 is to determine whether the supercharging pressure P _B is equal to the conventional P _B
Only P ₀ than * to a high eye has the function of the movable vane 16 to the closing side. In step 104, P _B <P _B * + P
If not _0, Step 10 in order to prevent engine breakdown
9, the movable vane 16
On the open side. Steps 103, 104, and 108 correspond to control for prolonging the movable vane closed state when the engine is cold, sufficiently increasing the supercharging pressure, further improving acceleration, and improving engine warm-up.

If it is determined in step 101 that the vehicle is in the deceleration state and the routine proceeds to step 106, it is determined in step 106 whether or not the engine speed NE is smaller than a predetermined speed NE ** (a value allowable in the compressor surging characteristic). . NE
If it is not <NE **, there is no possibility of entering the surging area. Therefore, the process proceeds to step 108, and the opening of the movable vane 16 is delayed so that the state where the diaphragm 4 is maximized and the movable vane is kept closed. If NE <NE ** in step 106, the routine proceeds to step 107, where the supercharging pressure P _B
Is larger than a predetermined value P _B ** (a value allowed in the compressor surging characteristic). P _B > P
If it is not _B **, there is no risk of entering the surging area. Therefore, the process proceeds to step 108, and the opening of the movable vane 16 is delayed so that the state where the throttle 4 is maximized is continued and the movable vane is kept closed. In step 107, P _B
If> P _B **, there is a possibility of entering the surging area. Therefore, the process proceeds to step 109, in which the amount of the diaphragm 4 is minimized so that the movable vane 16 is opened immediately. Step 10
Routes 1, 106, 107, and 109 cause the movable vanes 16 to temporarily open, reduce the turbine speed, reduce the compressor speed, and temporarily increase the boost pressure when the accelerator is rapidly closed after acceleration. And controls to prevent the occurrence of surging on the compressor discharge side.

In the above, the case where the throttle 4 is provided in the operating pressure input path 19 to delay the operating pressure of the operating pressure source 2 from being applied to the operating pressure chamber of the actuator 1 during a transition has been described. Alternatively, the operating pressure source 2
Even if the operating pressure is temporarily weakened, the same effect as described above (the effect of delaying the application of the operating pressure and prolonging the state in which the drive vane 16 is closed) can be obtained. include.

[0021]

According to the first to fourth aspects of the present invention, since the throttle is provided, the application of pressure to the actuator is delayed even if the engine operating condition becomes a specific condition in which the movable vane is closed to open during transition. , Delays that the movable vanes open. By this, at the time of transition, when the exhaust gas temperature is not enough,
Since the closed state of the movable vane is maintained for a predetermined time, the supercharging pressure is sufficiently increased, and sufficient acceleration performance can be obtained during a transition. According to the third aspect, the throttle amount is made larger in the cold state than in the warm state (the time for the large throttle amount is prolonged), so that the acceleration performance in the cold state is improved and the warm-up property is improved. Improve. This is particularly effective for diesel vehicles whose exhaust temperature rises slowly compared to gasoline engine vehicles. According to the fourth aspect, at the time of deceleration, when the rotation speed is equal to or less than the predetermined rotation speed, the throttle amount is temporarily reduced, so that the movable vane is temporarily opened to suppress an increase in the supercharging pressure and reduce the surging of the compressor. Can be avoided. According to the fifth aspect, the same effect as that of the first aspect can be obtained even if the pressure of the operating pressure source of the actuator is temporarily reduced during transition instead of the throttle.

[Brief description of the drawings]

FIG. 1 is a system diagram of a control device for a variable capacity turbocharger according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram of the device of FIG.

FIG. 3 is a flowchart of a control routine of the apparatus shown in FIG. 1;

FIG. 4 is a schematic sectional view near a turbocharger.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Actuator 2 Operating pressure source 3 CPU 4 Throttle (including variable throttle) 5 Engine speed signal 6 Engine load signal 7 Supercharging pressure signal 8 Water temperature signal of engine cooling water 10 Turbocharger 11 Turbine 12 Compressor 16 Moving vane 17 Unison ring 19 Working pressure input path

Claims (5)

[Claims] 1. A variable displacement turbocharger control device for controlling opening and closing of a movable vane by an actuator operated by a fluid, wherein a throttle is provided in an operating pressure input path to the actuator. Control device. 2. The variable displacement turbocharger control device according to claim 1, wherein said throttle is a variable throttle. 3. The control device for a variable displacement turbocharger according to claim 2, wherein the throttle is a variable throttle having a larger throttle amount when the engine is cold than when the engine is warm. 4. The variable displacement turbocharger control device according to claim 2, wherein the throttle is a variable throttle whose throttle amount is temporarily reduced when the engine speed is lower than a predetermined speed during deceleration. 5. A control device for a variable displacement turbocharger which controls opening and closing of a movable vane by an actuator operated by a fluid, wherein an operating pressure is temporarily reduced in an operating pressure input path to the actuator during an engine transition. A control device for a variable capacity turbocharger, characterized in that a source is connected.