JPS6056127A - Control device for variable displacement type turbo-charger - Google Patents

Abstract

PURPOSE:To aim at shortening the time of acceleration, by providing such an arrangement that the passage area of an exhaust gas introduction passage led to a turbine is made variable with the use of a displacement changing means which is controlled in accordance with the rotational speed and load of the engine so that the above-mentiond passage area is controlled to be sufficiently small upon acceleration. CONSTITUTION:A movable reed part 43 is swingably disposed in an introduction passage section for the turbine scrol of a turbo-charger 25 so that the passage area of introduction exhaust gas is made variable. This movable reed 43 is rotated by a vacuum actuator 47 through a rod 45, etc. Further, the vacuum actuator 47 is controlled by a control pressure which is produced by a vacuum pump 55 and is regulated in accordance with the opening degree of a solenoid valve 57. This solenoid valve 57 is controlled by a control unit 29 in accordance with the outputs of an air-flowmeter 24 and a crank angle sensor 34, an controls such that it throttles the introduction passage area to a predetermined value upon detection of acceleration, and also enlarges the introduction passage area in accordance with the operating condition of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a control device for a variable displacement turbocharger.

(Prior art) Generally, the boost pressure of a turbocharged engine is controlled by an exhaust bypass mechanism that bypasses exhaust gas and reduces the flow rate flowing into the turbine, and the turbine inlet pressure is uniquely determined by the turbine capacity. be done. Therefore, using a small flow Σ bin will increase torque at low speeds but decrease torque at high speeds, and using a high flow turbine will increase torque at high speeds but decrease torque at medium and low speeds. Therefore, variable displacement turbochargers have been proposed that can vary the capacity of the turbine depending on the operating state of the engine and increase torque from a low speed range to a high speed range.

As a conventional variable displacement turbocharger and its control device, for example, the one shown in Fig.
03IO Publication @) is known. In FIG. 1, ■ is a turbine housing that defines the scroll 2, and the scroll inlet portion 2A of the turbine housing 1 is
is provided with capacity variable means 3 for varying the passage area. The capacity variable means 3 includes a movable member 4 extending near the scroll entrance portion 2A on the inner circumferential wall of the housing 1, and a movable member 4 connected to the movable member 4 by a rod 5 to move the movable member 4 to adjust the passage of the scroll entrance portion 2A. As shown in FIG. 2, the actuator 6 moves the rod 5 in its axial direction based on a signal from a function generator 8 inputted via an amplifier 7. The movable member 4 is moved to change the turbine capacity. The function generator 8 receives a signal from a potentiometer 10 that detects the position of the accelerator lever 9, and a signal from an F/V converter I2 that converts the engine speed detected by the engine speed detection means 11 into a voltage. and the function generator 8 inputs the engine rotation speed Ne and the position of the accelerator lever (that is, the position of the accelerator lever is R).
, , R2, R3 (accelerator rack position operated) R, a signal is sent to the actuator 6 via the amplifier 7 so that the opening degree of the passage of the scroll entrance portion 2A becomes as shown in FIG. Output. This scroll entrance part 2
The opening degree Y of A is given by the following equation.

2 for Y-, 2 for R+, 3 for Ne+, where k,, k2-, and 3 are constants, R is the accelerator rack position, and the opening degree Y of this scroll inlet portion 2A has an upper limit ( i.e. maximum relationship) OL and lower 1
! ]! (that is, a minimum opening degree) CL is provided, and the scroll entrance portion IA changes with the opening degree Y within the range of this upper limit OL and lower limit CL.

For example, when the engine rotation is stable at point A in Figure 4, if you operate the accelerator lever 9 to set the accelerator rank position to R2 in order to accelerate, the moment you operate the accelerator lever 9, the engine rotation is Since the number Ne is the same, the opening degree Y of the scroll inlet portion 2A tries to close to the fully closed point B', but since the lower limit CL is provided for the opening degree Y, it will not reach the lower limit CL, which is point B. Move. Thereafter, as the engine speed Ne increases, the opening degree Y of the scroll inlet portion 2A moves from point B to point 0, and then moves along the line of the accelerator rack position R2 and gradually opens. Therefore, compared to a turbocharger with a fixed passage area, more intake air can be obtained during acceleration, and better combustion can be achieved.

However, in such a conventional variable displacement turbocharger control device, the passage area of the scroll inlet is adjusted based on the engine speed and the accelerator rack position, and the passage area of the scroll inlet is kept at a predetermined level during acceleration. After that, when the engine speed exceeds the engine speed determined by the accelerator rank position, the passage area of the scroll entrance is opened, so for engine protection, the minimum opening of the scroll entrance is The minimum passage area of the scroll inlet cannot be set too small, and the rate of increase in intake air temperature and cylinder wall temperature change due to changes in engine operating conditions (e.g. gear ratio of transmission). There has been a problem in that it is not possible to obtain the optimum supercharging pressure corresponding to G, and it is not possible to sufficiently shorten the acceleration time.

(Object of the Invention) Therefore, the present invention controls the passage area of the exhaust gas introduction passage to the turbine based on the engine speed and load, and also sufficiently reduces the passage area of the exhaust gas introduction passage during acceleration. By widening the passage area based on operating conditions, the aim is to sufficiently shorten acceleration time while preventing engine overheating and knocking.

(Structure of the Invention) The control device for a variable capacity turbocharger of the present invention includes a fifth
As shown in the figure, there is an engine speed detection means for detecting the engine speed, a load detection means for detecting the engine load, an engine state detection means for detecting the engine operating state, and an engine speed detection means for detecting the engine speed. A variable capacity turbo that changes the supercharging pressure of the intake air supercharged by the compressor wheel by changing the passage area of the exhaust gas introduction passage that acts on the turbine wheel using the variable capacity means. a charger, a control means for controlling the capacity variable means so that the boost pressure is optimal for the engine based on the engine rotation speed and the intake flow rate;
Acceleration control means controls the capacity variable means to narrow down the passage area of the introduction passage to a predetermined size and expand the passage area of the introduction passage based on a signal from the engine condition detection means during acceleration. By doing so, the acceleration time can be sufficiently shortened while preventing engine overheating and knocking during acceleration.

(Example) Hereinafter, the present invention will be described in detail based on the drawings.

6 to 8 are diagrams showing a first embodiment of the present invention.

First, to explain the configuration, in FIG. 6, 21 is an engine body, and intake air is introduced into the engine body 21 through an intake pipe 22 and an intake manifold. The intake pipe 22 includes an air flow meter (intake amount detection means) 24,
A space is provided between the compressor wheel chamber of the turbocharger 5, the throttle valve 27, and the relief valve.
is input to the control unit 29.

The intake air is pressurized by a compressor wheel housed in the compressor wheel chamber, and after its flow rate is regulated by a throttle valve 27, it is distributed and supplied to each cylinder of the engine body 21 by an intake manifold 23. A boost pressure sensor 31 and an intake temperature sensor 32 are attached to the intake manifold, and the boost pressure sensor 31 detects the pressure of intake air in the intake manifold n and outputs it to the control unit 29. The intake temperature sensor 32 detects the temperature of the intake air in the intake manifold n and outputs it to the control unit 29, and the opening degree of the throttle valve 27 is detected by the throttle opening sensor (acceleration state detection means) 33 and is controlled. It is output to unit 29. In addition, the engine rotation speed Ne is determined by a crank angle sensor (engine rotation speed detection means) 3.
4 and output to the control unit 29. Exhaust gas from the engine is collected in an exhaust manifold 35 and discharged through an exhaust pipe 36, and the exhaust pipe 36 is provided with a capacity variable means 37 and a turbine wheel chamber 3B containing a turbocharger. The compressor wheel 30 is disposed within the turbine wheel chamber 38.
A turbine wheel 39 connected to is housed,
The flow velocity of the exhaust gas acting on the turbine wheel 39 is changed by the capacity variable means 37. That is, as shown in FIG. 7, the turbine wheel chamber 38 has an annular scroll 40 formed to surround a turbine wheel (see FIG. 6) 39, and the area of the scroll 40 is the same as that of the introduction passage. It gradually becomes smaller as it goes downstream from 41 (in the direction of the arrow in the figure). This scroll 40
A movable tongue portion 43 is provided at the confluence of the introduction passage 41 and the terminal end portion 42 of the scroll 40, and the movable tongue portion 43 swings about a shaft 44 in a direction to expand and contract the introduction passage 41.

This shaft 44 is connected via an arm 46 to a rod 45 shown in FIG. 6, and the rod 45 is connected to a diaphragm 48 of a negative pressure actuator 47. The negative pressure actuator 47 is operated by a diaphragm 48.
The inside of the diaphragm 9 is divided into a negative pressure chamber and an atmospheric chamber 51, and a spring 52 that biases the diaphragm 48 toward the atmospheric chamber 51 is housed in the negative pressure chamber 50. In addition, negative pressure chamber (capital)
is connected to a negative pressure tank 54 through a negative pressure passage 53, and the negative pressure of the negative pressure pump 54 is supplied by a negative pressure pump δ. The negative pressure tank 54 is always maintained at a predetermined negative pressure because it is controlled by a negative pressure switch 56 that turns off its contact terminal when the negative pressure in the tank 54 becomes lower than a predetermined negative pressure. The negative pressure passage 53 is connected to the solenoid valve 5.
The solenoid valve 57 is duty-controlled by the control unit 29. That is, the negative pressure introduced into the negative pressure chamber 50 of the negative pressure actuator 47 changes by changing the duty ratio of the solenoid valve 57, and when the duty ratio increases and the negative pressure in the negative pressure chamber 5o becomes weaker, the diaphragm 4 Move to the atmospheric chamber 51 side. This movement of the diaphragm 48 causes the rod 45, arm 46 and shaft 44 to move, and the movable tongue part swings to change the introduction passage 41.

The movable tongue portion 43, the shaft 44, the arm 46, the rod 45,
Negative pressure actuator 47, negative pressure passage 53, negative pressure tank 5
4, negative pressure pump 55, negative pressure switch 56 and solenoid valve 5
Reference numeral 7 denotes a capacity variable means 37 that changes the passage area of the exhaust gas introduction passage 41 that acts on the turbine wheel 39 as a whole.
Configure. Alternatively, a step motor or the like may be used as the capacity variable means.

The control unit 29 is mainly composed of a microcomputer including a microprocessor, a memory, and an interface, and the interface of the control unit 29 includes the air flow meter 2.
4. Signals from a boost pressure sensor 31, an intake air temperature sensor 32, a throttle opening sensor 33, and a crank angle sensor 34 are input. Among these signals, analog signals are inputted as digital signals via an A/D converter. The memory temporarily stores programs that control the microprocessor, various data necessary for calculations performed by the microprocessor, and data imported from outside.The microprocessor uses these data to calculate fuel injection amount, injection timing, and other data according to the above program. The ignition timing and the like are calculated to output the injection signal S1 and the ignition signal SP appropriate for the operating condition, and the duty value of the electromagnetic valve 57 is calculated to output the control signal Sc from the interface.

Next, the operation will be explained based on the flowchart shown in FIG. In the figure, P, -Pl& indicate each step of the flowchart.

The control calculation of the present invention is executed, for example, once per rotation or once every fixed period of time. When the program starts, the engine speed Ne and the intake air flow rate Q^ are input at Pl, and the intake supercharging pressure P^ and the intake air temperature T^ are input at P2 and P3. Next, at P-4, it is determined whether or not it is in an acceleration state based on the throttle opening, and if it is not in an acceleration state, at p, the supercharging pressure P^ is greater than the specified value Po, but it is determined based on the experimental value from the tongue skin etc. is set. When boost pressure PA is smaller than specified value Po (P4≦P.

First, look up the duty value from the table map input in the memory and obtain the basic duty value Dp.
The duty value reduced by a predetermined amount Do is set as the basic duty value DM (DM=Dp-Do). Then, it is determined in P8 whether this basic duty value DM is between the upper limit value Du and the lower limit value. , Du≧1)
When t≧D, in D9 the basic duty value DM is set as the control duty value Dc and stored in the memory;
At P, a signal SC of the control duty value Dc is outputted to the solenoid valve 57 via the interface. Further, when Dx>Du in P8, an upper limit value T3u is set as the basic duty value difference in PIl, and in P9, the basic duty value DM, which is this upper limit value Du, is set as the control duty value Dc and stored in the memory. , , outputs the signal Sc of the control duty value (Dc=Du) to the solenoid valve 57 via the interface.

Then, in PIl, when DM < DL, the lower limit value DL is set as the basic duty value DM in PIz, and similarly in P9, the basic duty value DM, which is the lower limit value DL, is set as the control duty value Dc and is stored in the memory. A signal Sc of the stored P-ad control duty value (Dc=DL) is output to the solenoid valve 57 via the interface.

The upper limit value Du and lower limit value DL are used to prevent the program from running out of control, protect the program from noise, and use the solenoid valve 57.
Established for the protection of For example, the solenoid valve 57
operates at a constant cycle, so on the upper limit side, the maximum
At 0 Hz, it will operate approximately every 51.2 ms, but at this time, if the ON duty exceeds 100%, it will flow to the next cycle, which may cause malfunction or failure of the solenoid valve 57. becomes. Therefore, an upper limit (iil)u is provided to prevent this problem. In this way, when the engine is not in an acceleration state, the engine rotation speed Ne and the intake air flow rate per rotation QA/
Based on Ne, it is possible to obtain the control duty value DC that provides the optimal boost pressure for the engine obtained from the experimental value.

On the other hand, when it is in the acceleration state at step p-+, the basic throttle duty value DMM and the holding time T of this value are experimentally determined in PI3 based on the engine speed Ne and the intake air flow rate per revolution QA/Ne. Each of the basic aperture duty values DMM is read from a table map previously input into the memory and stored as the basic duty value DM. Next, in p14, it is determined whether or not the holding time T of the basic aperture duty value DMM, which is set as the basic duty value DM, has been exceeded (a timer is activated when it is determined that the acceleration state is present). is corrected by decreasing it by a certain amount per unit time. This is because the movable nozzle is opened as the air flow rate increases, as shown in FIG. 11. Furthermore, P
At lk, it is determined whether the intake air temperature TA is higher than an upper limit value (determined by experiment based on the limit of occurrence of non-king and engine strength) Tu. When T^≦Tu, the basic duty value DM is stored in the memory as the control duty value Dc through step PII in two days. Then, the flow is outputted to the solenoid valve 57 via the interface, and the flow starts flowing again. However, when the intake air temperature T^ increases and becomes TA>Tu, the basic duty (+tD
A duty value reduced by a predetermined amount DA from s is set as a basic duty value DM, and is stored in the memory as a control duty value Dc via P8 in P9.

It is output to the solenoid valve 57 via the interface. That is, when in an acceleration state, the duty value is increased to the basic aperture duty value DM (which may be the vehicle speed depending on the case where the duty value corresponds to the rotational speed and load) and the introduction passage 41 is
The passage area of is narrowed down to the optimum value, and this throttling holding time T is also determined by engine speed Ne and intake air flow rate per revolution QA/Ne.
to maximize the effect of exhaust gas on the Tarchin wheel 39. As a result, sufficient supercharging pressure can be obtained and acceleration time can be sufficiently shortened. On the other hand, if the boost pressure is increased, the intake air temperature rises faster and the acceleration time is shortened, but this causes problems such as non-king and strength problems due to engine overheating. However, in this embodiment, the intake air temperature TA is detected, and the intake air temperature 1゛A is the upper limit value T.
When u exceeds, the duty value is lowered and the introduction passage 41 is slightly widened to prevent non-king and engine overheating.

In this way, during acceleration, the acceleration time can be sufficiently shortened while preventing the occurrence of non-king and overheating of the engine.

FIGS. 9 and 10 are diagrams showing a second embodiment of the present invention. In describing this embodiment, only the same reference numerals are given to the same components as in the first embodiment, and the explanation thereof will be omitted. In FIG. 9, reference numeral 58 denotes a knock sensor (engine state detection means) that detects knocking occurring in the engine as an operating state of the engine, and a knock signal SN related to the knock sensor is input to the control unit 4. In the control unit 29, duty control of the solenoid valve 57 is performed based on the flowchart shown in FIG. Omitted.

In addition, in FIG. 10, PI, P2, P-~pt2 and p2
-, xp2 to '4 indicate each step of the flow.

In this control, a knock signal is input at P2-1, and a basic aperture duty value D is input at P2-2 during acceleration.
MM is set as the basic duty value DM after lookup, and the protection times are compared in P2-3 as in the previous embodiment. Next, at p2-, it is determined from the knock signal SN whether or not knocking has occurred, and if knocking has occurred and no knocking has occurred, steps P8 to P are performed on the basic duty value DM. When non-king occurs in p2-4, a duty value obtained by decreasing a predetermined amount DA from the basic duty value DM replaced in P2-5 is set as the basic duty value DM, and then this basic duty value DM is set as the basic duty value DM. Processing from P8 to P is performed. Therefore, in this example,
During acceleration, the duty value is set to the basic throttle duty value DM, and the passage area of the introduction passage 41 is optimally narrowed to shorten the acceleration time. When non-king occurs, the duty value is reduced to widen the introduction passage 41 to avoid knocking and prevent the engine from overheating.

In each of the above embodiments, an intake air temperature sensor and a knock sensor are used as the engine state detection means, but the invention is not limited to these.

(Effects) According to the present invention, it is possible to reduce the passage area of the introduction passage for exhaust gas acting on the turbine wheel during acceleration, and to expand the passage area of the introduction passage before overheating or non-king occurs in the engine state. Therefore, the acceleration time can be sufficiently shortened while preventing engine overheating and non-king.

[Brief explanation of the drawing]

1 to 4 are diagrams showing a conventional control device for a variable displacement turbocharger. FIG. 1 is a sectional view of the turbocharger, FIG. 2 is a block diagram showing the control circuit of the actuator, and FIG. is a characteristic diagram showing the relationship between scroll inlet opening and engine speed, and Figure 4 is a diagram explaining its effect.
FIG. 5 is an overall configuration diagram of a control device for a variable displacement turbocharger according to the present invention, and FIGS. 6 to 8 are diagrams showing a first embodiment of the control device for a variable displacement turbocharger according to the present invention.
7 is a cross-sectional view of the variable displacement turbocharger, FIG. 8 is a flowchart of the control unit, and FIGS. FIG. 9 is an overall schematic diagram of the second embodiment, and FIG. 10 is a flow chart of the control of the control unit. 11th
The figure is a graph for explaining acceleration correction. 24...--Intake air amount detection means, 5--Turbocharger, 30--Compressor wheel, 32.5B--Engine state detection means, 33-
--1--Acceleration state detection means, 34-----1 Engine rotation speed detection means, 37-.-
Capacity variable means, 39--Turbine wheel, 41--Introduction passage. nihe0-se3shig

Claims (1)

[Claims] (11 Engine for detecting the rotational speed of the engine;
il Rotation speed detection half screen, load detection means for detecting the engine load, engine state detection means for detecting the operating state of the engine, acceleration state detection means for detecting the acceleration state, and exhaust gas acting on the turbine wheel. A variable displacement turbocharger that varies the supercharging pressure of the intake air supercharged by a compressor wheel by changing the passage area of the introduction passage using a capacity variable means, and a variable displacement turbocharger that varies the supercharging pressure of the intake air supercharged by the compressor wheel, and the supercharging pressure is applied to the engine based on the engine speed and load. A control means for controlling the capacity variable means to optimize the capacity, and during acceleration, narrowing down the passage area of the introduction passage to a predetermined size and expanding the passage area of the introduction passage based on a signal from the engine condition detection means. acceleration control means for controlling the capacity variable means so as to
A control device for a variable capacity turbocharger, comprising: (2) The engine condition detection means is an intake air temperature sensor that detects the intake air temperature, and the acceleration control means controls the capacity variable means to expand the passage area of the introduction passage when the intake air temperature exceeds a predetermined temperature. A control device for a variable capacity turbocharger according to claim 1, characterized in that: (3) The engine state detection means is a knock sensor that detects non-king occurring in the engine, and the acceleration control means controls the capacity variable means to expand the passage area of the introduction passage when non-king occurs. A control device for a variable displacement turbocharger according to claim 1.