JPS6329026A - Supercharge pressure controller for internal combustion engine equipped with variable capacity type exhaust turbocharger - Google Patents

Abstract

PURPOSE:To suppress the reduction of the engine output due to the increase of the exhaust pressure by controlling a varying means for the area of an exhaust inlet nozzle and an opening/closing means for an exhaust bypass passage, in preference to a supercharge pressure control means, according to the gear position of a speed change gear. CONSTITUTION:An opening/closing means B is installed into an exhaust bypass passage which makes a detour around the exhaust turbine A of a turbocharger, and a varying means C for varying the area of the exhaust inlet nozzle of the exhaust turbine A is installed. The opening/closing means B and the varying means C are controlled by a supercharge pressure control means E according to the output of a supercharge pressure detecting means D. In this case, a gear position detecting means F for detecting the gear position of a speed change gear is installed. Then, the opening/closing means B and the exhaust inlet nozzle area varying means C are controlled by a gear position detecting means G according to the gear position detected by the detecting means F in preference to the supercharge pressure control means E.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a supercharging pressure control device for a variable displacement exhaust turbocharging internal combustion engine in which the area of the exhaust inlet nozzle of an exhaust turbine is variably controlled.

<Prior art> In an exhaust turbocharger for an internal combustion engine, the exhaust energy of the engine drives an exhaust turbine to rotate, and a compressor connected to the turbine compresses intake air and supplies it to the engine (supercharging). However, in the low engine rotation range where the exhaust energy is small, sufficient supercharging of the engine could not be achieved. For this reason, a variable capacity exhaust turbocharger has been proposed that changes the amount of exhaust energy supplied to the exhaust turbine depending on the operating state of the engine.
and FIG. 6 (see Japanese Unexamined Patent Publication No. 182318/1983).

In this figure, 20 is an exhaust turbine, 21 is a turbine housing that covers the outer periphery of this exhaust turbine 20, and a flap 2 is attached to an exhaust inlet nozzle 21a of the turbine housing 21.
2 is rotatably supported.

This flap 22 changes the area of the exhaust inlet nozzle 21a by its rotation (rotation driven by an actuator not shown). By rotating clockwise, the area of the exhaust inlet nozzle 21a is minimized (FIG. 5), increasing the velocity of the exhaust gas flowing into the exhaust turbine 20, and increasing the boost pressure. When the boost pressure reaches the initially set predetermined boost pressure, the area of the exhaust inlet nozzle 21a is increased by gradually rotating the flap 22 counterclockwise in the figure (Figure 6). The amount of exhaust energy supplied to the turbine 20 is adjusted to generate a target boost pressure.

Furthermore, when the flap 22 is rotated counterclockwise in the figure and the area of the exhaust inlet nozzle 21a reaches its maximum, the exhaust bypass valve that opens and closes the passage that bypasses the exhaust turbine 20 is gradually opened. In this way, the bypass displacement is increased and controlled to reach the target supercharging pressure.

<Problems to be Solved by the Invention> However, as described above, even if the area of the exhaust inlet nozzle 21a is narrowed (reduced capacity) to increase the boost pressure in order to hasten the build-up of the boost pressure, at this time, Depending on the gear position of the transmission attached to the engine and the engine load condition, the exhaust pressure may rise above this, resulting in an increase in cylinder pumping loss and residual gas loss due to the increase in exhaust pressure, rather than the effect of supercharging. In some cases, negative effects such as increase in engine speed may prevail, resulting in a decrease in engine output and deterioration in acceleration. In addition, if the residual gas increases while the flap 22 is closed in this way, even after opening the flap 22 and increasing the area of the exhaust inlet nozzle 21a, the influence of the residual gas may remain for a while, resulting in a decrease in output. was there.

The present invention has been made in view of the above problems, and provides supercharging for an internal combustion engine equipped with a variable displacement exhaust turbocharger, which can prevent a decrease in engine output due to an increase in exhaust pressure and obtain a sufficient supercharging effect. The purpose is to provide a pressure control device.

Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. An inlet nozzle area variable means, a supercharging pressure detecting means for detecting supercharging pressure, and a supercharging pressure control means for controlling the opening/closing means and the exhaust inlet nozzle area variable means in accordance with the detected supercharging pressure. A supercharging pressure control device for an internal combustion engine with a variable displacement exhaust turbocharger, comprising: a gear position detection means for detecting a gear position of a transmission attached to the engine; and a gear position of the transmission detected thereby. A gear position control means is provided for controlling the opening/closing means or the exhaust inlet nozzle area variable means with priority over the boost pressure control means.

Effect> Since the increase in exhaust pressure is approximately proportional to the increase in engine speed, the rate of increase in exhaust pressure becomes higher when the load on the engine is smaller and the gear ratio is smaller. Therefore, if the area of the exhaust inlet nozzle is the same, the smaller the gear ratio, the higher the rate of increase in exhaust pressure, and the more likely the adverse effects of the increase in exhaust pressure will occur.

Therefore, by varying the exhaust inlet nozzle area or opening and closing the exhaust bypass passage in a direction that reduces exhaust pressure according to the gear position, the exhaust passage resistance can be reduced, the negative effects of an increase in exhaust pressure can be avoided, and the supercharging effect can be improved. The goal is to get enough.

In other words, if you are attempting to hasten the build-up of supercharging pressure by narrowing down the exhaust inlet nozzle area, but the exhaust pressure is rising rapidly, even if you try to improve engine output through the supercharging effect, the exhaust pressure loss will cause Since an output improvement effect cannot be obtained, the exhaust pressure is reduced to an extent that a supercharging effect can be obtained, depending on the gear position that indirectly indicates a tendency for the exhaust pressure to increase.

<Example> Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows a system diagram of the first embodiment. In a second embodiment, which will be described later, a throttle sensor 16, which is surrounded by a dashed line in the figure, is added to the configuration of the first embodiment.

In this variable capacity exhaust turbocharger, the turbine 3a of the exhaust turbocharger 3 is rotationally driven by the energy of the exhaust gas discharged from the engine l through the exhaust passage 2.
The compressor 3b, which is connected to the
supply supercharged (compressed) air to the

The exhaust inlet nozzle 3C of the turbine housing that covers the outer periphery of the turbine 3a is provided with a flap 5 (fifth flap) for varying the area of the exhaust inlet nozzle 3C as described in the conventional example.
Like the flap 22 shown in the figure and FIG.

In addition, the upstream and downstream of the turbine 3a are short-circuited, and the turbine 3a
An exhaust bypass valve 8 as an opening/closing means is interposed in the exhaust bypass passage 7 through which exhaust gas flows by bypassing the exhaust gas, and the exhaust bypass valve 8 is driven to open and close by an actuator 9.

The operation of the actuator 6.9 is controlled by a control unit 10 built in a microcomputer, and the control unit 10 includes a supercharging pressure detection means installed in the intake passage 4 downstream of the compressor 3b. The supercharging pressure PC detected by the supercharging pressure sensor 11 of the engine and the gear position of the transmission attached to the engine detected by the gear position sensor 12 as a gear position detecting means are input, and these detection results are input. Actuator 6.9 is actuated based on. That is, in this embodiment, the control unit 10 corresponds to supercharging pressure control means and gear position control means.

Next, control by the control unit 10 will be explained based on the flowchart of FIG.

In step 1 (indicated as "S" in the figure, the same applies hereinafter), the supercharging pressure Pe detected by the supercharging pressure sensor 11 and the gear position of the transmission detected by the gear position sensor 12 are calculated. input.

In step 2, the supercharging pressure P input in step 1 is compared with the predetermined supercharging pressure P1, and if Pc<P, the area of the exhaust inlet nozzle 3C is reduced to increase the exhaust flow velocity, and the supercharging pressure is increased. The pressure rises quickly, but the area of the exhaust inlet nozzle 3C (flap 5)
(initial opening degree) is determined by the gear position of the transmission attached to the engine.

That is, when PC<PI, proceed to the next step 3 and search for the initial opening degree of the flap 5 that has been set in advance in correspondence with the gear position 1. In step 4, the flap 5 is rotated by the actuator 6 so as to have the initial opening degree determined by the search result. This is achieved by narrowing down the area of the exhaust inlet nozzle 3C according to the gear position.
This is to speed up the build-up of the supercharging pressure PC in the engine low rotation region.

Here, the initial opening degree corresponding to the gear position is set to be larger as the gear ratio is lower. This is because when the gear ratio is low, the load on the engine is lighter, so the engine speed increases rapidly, and the exhaust pressure also increases rapidly, so the exhaust inlet nozzle 3c The aim is to alleviate this increase in exhaust pressure by increasing the area of the exhaust gas.

In this way, if the increase in exhaust pressure can be suppressed, the engine output can be increased favorably and acceleration performance can be improved.

Generally, there is a relationship between the engine output increase rate ΔT, the boost pressure increase rate ΔPc, and the exhaust pressure increase rate ΔPt as follows: ΔT−αΔPe−βΔPt (α and β are positive coefficients) Therefore, even if the boost pressure Po rises quickly,
If the exhaust pressure PL increases rapidly, the negative effects of the increase in exhaust pressure (increase in cylinder pump loss, increase in residual gas, etc.) will outweigh the effects of supercharging, and the rise in engine output will slow down. If the increase in exhaust pressure Pt is suppressed by controlling the flap 5 to an initial opening degree according to the gear position as described above, a supercharging effect can be quickly obtained and acceleration performance can be improved.

On the other hand, when pc>p+, the boost pressure PC
In order to suppress the rise in the exhaust pressure, the exhaust pressure control shown in steps 5 to 7 is performed.

In step 5, it is determined whether or not the flap 5 is fully open, and if the determination is NO (if it is not fully open), the process proceeds to step 6, where the flap 5 is rotated a predetermined amount in the opening direction, and the exhaust inlet is opened. The area of the nozzle 3c is expanded. In addition, if the determination is YES in step 5 (when the flap 5 is fully open), proceed to step 7 and open the exhaust bypass valve 8 by a predetermined amount. In other words, if PC>PI, first, By rotating the flap 5 in the opening direction by a predetermined amount, an increase in supercharging pressure PC is suppressed, and when the flap 5 is fully open, the exhaust bypass valve 8 is opened to reduce the exhaust energy applied to the turbine 3a. This is to control the supercharging pressure Pe to around the skin regular supply pressure P.

On the other hand, when Pc#P, the supercharging pressure PC is the target pressure, so the engine is returned as is without controlling the rotational drive of the flap 5 or controlling the opening/closing of the exhaust bypass valve 8.

Next, a second embodiment of the present invention will be described.

The hardware configuration of the second embodiment is the first hardware configuration shown in FIG.
A throttle sensor 16 for detecting the opening degree of the throttle valve 15 is added to the configuration of the embodiment, and the other configurations are the same.

The opening degree of the throttle valve 15 detected by the throttle sensor 16 is input to the control unit 10.

Next, the operation of the second embodiment of this configuration will be explained based on the flowchart shown in FIG.

In addition, what is the limit when supercharging pressure Pc≧predetermined pressure P? O(
Since the exhaust energy control to bring the supercharging pressure PC to around the predetermined pressure P is the same as in the first embodiment, Pc<P
Only the control when it is I will be shown and explained.

When PC<PI, the area of the exhaust inlet nozzle 3C is narrowed to accelerate the rise of the supercharging pressure PC, but the rise of the exhaust pressure P that occurs simultaneously with the rise of the supercharging pressure PC is As mentioned above, it is affected by the gear position of the transmission, and also varies depending on the engine load before acceleration. For this reason, in this embodiment, during steady operation, the opening degree of the flap 5 (area of the exhaust inlet nozzle 3C) is variably controlled according to the gear position and engine load, as well as the throttle valve opening degree.

That is, in step 10, the gear position detected by the gear position sensor 12 and the opening degree α of the throttle valve 15 detected by the throttle sensor 16 are input.

In step 11, it is determined whether the engine is in a steady operating state based on the previously input throttle valve opening α and the current input value. Here, when it is determined that the engine is in a steady operating state, the process proceeds to the next step 12, where the initial opening degree of the flap 5 is set based on the gear position and the throttle valve opening degree α.

The initial opening degree of the flap 5 (minimum area of the exhaust inlet nozzle 3c) is preset and stored in the control unit 10 in correspondence with the gear position and the throttle valve opening degree α.
From this three-dimensional map, the initial opening degree corresponding to the operating state is searched and set.

On the other hand, when it is determined in step 11 that the engine is not in a steady operating state, the process proceeds to step 13, where the initial opening degree of the flap 5 is set by searching from a two-dimensional map of the gear position and the initial opening degree of the flap 5. Such control is similar to the first embodiment.

When the initial opening degree of the flap 5 is set in step 12 or step 13, the flap 5 is opened in step 14.
is rotated by the actuator 6 so that it has a set initial opening degree.

In this way, the flap 5 is adjusted based on the gear position and the engine load (throttle valve opening α in this embodiment) during steady operation.
If the initial opening degree, that is, the area of the exhaust inlet nozzle 3C is variably controlled, the exhaust pressure P,
The increase in exhaust pressure P can be effectively suppressed, and the adverse effects of the increase in exhaust pressure P can be avoided.

In other words, even if the gear position is the same, the exhaust pressure P during acceleration may vary depending on the engine load state during steady operation before acceleration.
Since the increase rate ΔPt of t changes, the exhaust inlet nozzle 3C is designed to suppress the exhaust pressure increase rate ΔP1 before acceleration.
By controlling the area of , it is possible to avoid the adverse effects of the increase in exhaust pressure Pt during acceleration and obtain a sufficient supercharging effect.

In both the first and second embodiments, the opening degree of the flap 5, that is, the opening of the exhaust inlet nozzle 3, depends on the gear position.
Although the area of C is variably controlled, since the purpose is to reduce the exhaust pressure P1, instead of controlling the flap 5, an exhaust bypass, which is conventionally closed until a predetermined supercharging pressure P is reached, is used. The opening of the valve 8 may be controlled to reduce the exhaust passage resistance. Furthermore, the area of the exhaust inlet nozzle 3C and the opening and closing of the exhaust bypass valve 8 may be controlled simultaneously.

(Effects of the Invention) As explained above, according to the present invention, in an internal combustion engine with a variable displacement exhaust turbocharger, the exhaust inlet nozzle area and the bypass displacement amount are controlled according to the gear position. This has the effect of preventing a decrease in engine output due to pressure rise, obtaining a good rise in supercharging pressure, and improving engine acceleration.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the present invention, Fig. 2 is a system diagram showing the first and second embodiments of the invention, Fig. 3 is a flowchart showing control in the first embodiment, and Fig. 4 is a system diagram showing the control in the first embodiment. FIGS. 5 and 6 are sectional views showing conventional examples of a variable displacement exhaust turbocharger, respectively. 1... Engine 2... Exhaust passage 3... Exhaust turbocharger 3a... Turbine 3b...
Compressor 3C...Exhaust inlet nozzle 4...
・Intake passage 5...Flap 7...Exhaust bypass passage 8...Exhaust bypass valve 10...Control unit 11...Supercharging pressure sensor, 12.
...Gear position sensor 15...Throttle valve 1
6...Throttle sensor patent applicant: Nissan Motor Co., Ltd., agent, patent attorney: Fujio SasashimaFigure 1

Claims (2)

[Claims] (1) An opening/closing means for opening and closing an exhaust bypass passage that bypasses the exhaust turbine, an exhaust inlet nozzle area variable means for varying the area of the exhaust inlet nozzle of the exhaust turbine, and a supercharging pressure detection means for detecting supercharging pressure; A supercharging pressure control device for an internal combustion engine with a variable displacement exhaust turbocharger, comprising: supercharging pressure control means for controlling the opening/closing means and the exhaust inlet nozzle area variable means according to the detected supercharging pressure; gear position detection means for detecting a gear position of a transmission attached to the transmission, and controlling the opening/closing means or exhaust inlet nozzle area variable means with priority over the boost pressure control means according to the detected gear position of the transmission. A supercharging pressure control device for an internal combustion engine with a variable displacement exhaust turbocharger, characterized in that a gear position control means is provided. (2) The gear position control means controls the opening/closing means or the exhaust inlet nozzle area variable means according to the gear position and engine load during steady engine operation. Boost pressure control device for internal combustion engines with capacity type exhaust turbocharger.