JPH06280592A - Control system for supercharging pressure - Google Patents

Abstract

PURPOSE:To quickly raise supercharging pressure by driving an exhaust bypass valve adjusting an exhaust gas quantity to be supplied to the exhaust gas turbine of a supercharger by means of an actuator, and limiting intake air on the lower stream side of the intake air compressor to be supplied to the actuator at raising supercharging pressure. CONSTITUTION:An engine 1 is provided with a turbocharger 6 of which the intake air compressor 6C is arranged on the upper stream side of an intake pipe 3 and the exhaust gas turbine 6T is arranged on the lower stream side of an exhaust pipe 5. An exhaust gas quantity to be supplied to the exhaust gas turbine 6T is adjusted by means of the exhaust bypass valve 8W of an exhaust bypass pipe 8, and the valve is driven by means of an actuator 10 according to the air pressure of a pressure chamber P. Meanwhile, intake air on the lower stream side of the compressor 6C is led to the pressure chamber P through lead pipes 9A, 9B. The pressure of intake air on the lower stream side led to the pressure chamber P is controlled by a pressure control means 11 of a lead branch pipe 9C. Further the flow of intake air on the lower stream side flowing in the lead pipe 9A is controlled by a flow control means 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supercharging pressure control system for controlling the supercharging pressure of a supercharger of an internal combustion engine by adjusting the opening of an exhaust bypass valve.

[0002]

2. Description of the Related Art Generally, as a technique for improving the output of an internal combustion engine, there is a supercharger (turbocharger) for forcibly increasing the amount of air burned in the internal combustion engine (intake amount). In order to control the supercharging pressure so that it does not rise excessively, this supercharger has an exhaust bypass pipe that bypasses a part of the exhaust gas to the exhaust turbine side of the supercharger, and this exhaust bypass pipe. The exhaust bypass valve is controlled by the exhaust bypass valve that adjusts the amount of exhaust gas that passes through and the intake pressure on the downstream side of the intake compressor of the supercharger (that is, the supercharging pressure of the supercharger) that is guided to the pressure chamber through the pressure guiding pipe. A supercharging pressure control device including a driving actuator is provided.

The actuator adjusts the opening degree of the exhaust bypass valve according to the magnitude of the boost pressure introduced into the pressure chamber. That is, when the supercharging pressure introduced to the actuator becomes larger than the target value, the opening degree of the exhaust bypass valve is increased to reduce the amount of exhaust acting on the exhaust turbine. On the contrary, when the supercharging pressure is smaller than the target value, the opening degree of the exhaust bypass valve is reduced to increase the amount of exhaust acting on the exhaust turbine. As described above, since the adjustment of the opening degree of the exhaust bypass valve depends on the magnitude of the boost pressure introduced into the pressure chamber of the actuator, conventionally, the magnitude of the boost pressure introduced into the pressure chamber of the actuator is adjusted. In order to reduce the supercharging pressure introduced into the pressure chamber of the actuator, the pressure reducing valve is branched and connected in the middle of the pressure guiding pipe, and the opening of this pressure reducing valve is adjusted to reduce the supercharging pressure of the supercharger. Was variably controlled to a predetermined target value. Such variable displacement type supercharging pressure control device is described in JP-A-62-225719 and JP-A-2-227521.

[0004]

In the conventional supercharging pressure control device, the intake pressure (supercharging pressure) on the downstream side of the intake compressor is always introduced (feedback) into the pressure chamber of the actuator via the pressure guiding pipe. The pressure reducing valve is branched and connected in the middle of the pressure guiding pipe, and only reduces the pressure transmitted in the pressure guiding pipe to a predetermined pressure. That is, one of the pressure reducing valves is connected to the pressure guiding pipe, and the other is opened to the atmosphere or connected to the upstream side of the intake compressor.

Therefore, when the opening of the pressure reducing valve is large, the intake pressure (supercharging pressure) on the downstream side of the intake compressor is hardly introduced into the pressure chamber of the actuator via the pressure guiding pipe, and the exhaust bypass valve is closed. All exhaust will act on the exhaust turbine. However, in the process in which the supercharging pressure rises (acceleration operation state), despite the supercharging pressure being reduced through the pressure guiding pipe and the pressure reducing valve,
Since the remaining pressure obtained by subtracting the reduced pressure from the intake pressure acts on the actuator, the exhaust bypass valve acts in accordance with the remaining pressure, which impedes a rapid increase in supercharging pressure.

On the other hand, when the opening of the pressure reducing valve is small, the intake pressure (supercharging pressure) on the downstream side of the intake compressor is directly introduced into the pressure chamber of the actuator.
In the same way as above, during the process where the boost pressure rises (acceleration operation state), the exhaust bypass valve gradually opens according to the magnitude of the boost pressure, and accordingly, part of the exhaust gas passes through the exhaust bypass pipe. Similarly, the rapid increase in boost pressure will be hindered.

The present invention has been made in view of the above points, and an object of the present invention is to provide a supercharging pressure control system capable of rapidly increasing the supercharging pressure even in the process of increasing the supercharging pressure. .

[0008]

A supercharging pressure control system according to the present invention is a supercharger comprising an intake compressor and an exhaust turbine, and an exhaust gas for adjusting the amount of exhaust gas supplied to an exhaust turbine of the supercharger. A bypass valve, an actuator that drives the exhaust bypass valve according to the atmospheric pressure of the pressure chamber,
A pressure guiding pipe that guides the intake air downstream of the intake compressor to the pressure chamber; pressure control means that is branched and connected to the pressure guiding pipe to control the pressure of the downstream intake air that is guided to the pressure chamber; and the pressure guiding pipe. Flow rate control means for controlling the flow rate of the downstream side intake air flowing into the.

[0009]

The supercharger is composed of an intake compressor and an exhaust turbine. The exhaust bypass valve is driven by an actuator and regulates the amount of exhaust gas supplied to the exhaust turbine of the supercharger. The actuator drives the exhaust bypass valve according to the pressure of the intake air on the downstream side of the intake compressor, which is guided to the pressure chamber via the pressure guiding pipe, and adjusts the opening thereof. At this time, the pressure control means is branched and connected to the pressure guiding pipe to control the pressure of the downstream side intake air introduced into the pressure chamber to be reduced. The flow rate control means controls the flow rate of the downstream intake air flowing into the pressure guiding pipe. Therefore, in the process of increasing the supercharging pressure (acceleration operation state), the flow control means limits the flow rate of the intake air on the downstream side of the intake compressor flowing into the pressure guiding pipe, so that the supercharging pressure is not introduced into the pressure chamber of the actuator. This causes the boost pressure to rise quickly. When the supercharging pressure rises and approaches the target value, the flow rate control means increases the flow rate of the intake air on the downstream side of the intake compressor flowing into the pressure guiding pipe,
Suppress an excessive rise in boost pressure. The control of the supercharging pressure above a predetermined value is performed by appropriately controlling the pressure control means and the flow rate control means.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a diagram showing a configuration example of a supercharging pressure control system of the present invention. The internal combustion engine 1 is a diesel engine or a gasoline engine equipped with a turbocharger 6. The fuel mixture is sucked into each cylinder of the internal combustion engine 1 through the air cleaner 2, the intake compressor 6C, the intake pipe 3, the intercooler 4, the throttle chamber 7 and the intake manifold 1A. The exhaust gas after the combustion and explosion is exhausted to the outside through the exhaust manifold 1B, the exhaust pipe 5 and the exhaust turbine 6T (or the exhaust bypass pipe 8). Fuel is injected from an injector (not shown).

A turbocharger 6 including an intake compressor 6C and an exhaust turbine 6T is provided upstream of the intake pipe 3 and downstream of the exhaust pipe 5. The intake pipe 3 is provided with an intake compressor 6C of the turbocharger 6, and the exhaust pipe 5 is provided with an exhaust turbine 6T of the turbocharger 6. The intake compressor 6C and the exhaust turbine 6T are mechanically connected via a rotary shaft. Therefore, the exhaust turbine 6T of the turbocharger 6
When is driven to rotate by the action of exhaust gas, the compressor 6C rotates in conjunction with this rotation, and supercharged intake air is introduced into the intake pipe 3.

Most of the intake air supercharged by the intake compressor 6C is introduced into the internal combustion engine 1 through the intake pipe 3, the intercooler 4, the throttle chamber 7 and the intake manifold 1A, but a part of the intake air is introduced into the pressure guiding pipe 9A. , 9
It is introduced into the pressure chamber of the actuator 10 via B.
The actuator 10 is divided by a diaphragm D into a pressure chamber P and an atmospheric pressure chamber A, and the atmospheric pressure chamber A is provided with a spring S. The spring S applies a pressing force to the diaphragm D toward the pressure chamber P. The diaphragm D is mechanically coupled to the exhaust bypass valve (waste gate valve) 8W via a connecting member such as a rod and a rotary lever. The opening degree of the exhaust bypass valve 8W is adjusted according to the movement of the diaphragm D.

Exhaust gas discharged from the internal combustion engine 1 acts on the exhaust turbine 6T via the exhaust pipe 5 and then is discharged to the outside, and passes through the exhaust bypass valve 8W and the exhaust bypass pipe 8 to pass through the exhaust turbine 6T. Some are bypassed and discharged to the outside. When the atmospheric pressure of the pressure chamber P is the same as the atmospheric pressure, the diaphragm D of the actuator 10 is pressed to the side of the atmospheric pressure chamber P (left side in the drawing) by the spring S, so that the exhaust bypass valve 8W is closed via the connecting member. . On the contrary, when the pressure in the pressure chamber P becomes larger than the atmospheric pressure, the diaphragm D moves to the spring S side (right side in the drawing) according to the magnitude of the atmospheric pressure.
The exhaust bypass valve 8W has an opening degree according to the moving amount of the diaphragm D, that is, the atmospheric pressure in the pressure chamber P. Therefore, the exhaust gas discharged from the internal combustion engine 1 bypasses the exhaust bypass pipe 8 by an amount according to the opening degree of the exhaust bypass valve 8W, and the other exhaust gas acts on the exhaust turbine 6T.

The branch pipe 9C is branched and connected to the pressure guiding pipe 9B,
It is open to the atmosphere via the pressure control valve 11. The pressure control valve 11 opens and closes according to a bypass control signal having a duty control value from the control means 13, and a branch pipe 9C.
The intake pressure of the pressure guiding pipe 9B, that is, the pressure chamber P is discharged to the outside through the pressure control pipe 9B to adjust the atmospheric pressure of the pressure chamber P. The pressure control valve 11 may discharge the intake pressure of the pressure chamber P to the upstream side of the intake compressor 6C. The pressure control valve 11 inputs a bypass control signal having a large duty control value,
Since the opening ratio is increased and more intake air in the pressure chamber P is exhausted to the outside, the air pressure in the pressure chamber P is reduced. On the contrary, the pressure control valve 11 reduces the opening ratio by inputting the bypass control signal having a small duty control value, and raises the atmospheric pressure of the pressure chamber P to the supercharging pressure in the intake pipe 3.

The flow control valve 12 functions as a throttle valve that variably controls the opening area of the pressure guiding tube 9A according to a control signal from the control means 13. In the process in which the supercharging pressure rises (acceleration operation state), the flow rate control valve 12 reduces the opening area of the pressure guiding pipe 9A so that the intake air on the downstream side of the intake compressor 6C is in the pressure guiding pipe 9.
Limit the flow into B. As a result, since the supercharging pressure is not introduced into the pressure chamber P of the actuator 10 in the process of increasing the supercharging pressure, the exhaust bypass valve 8W does not open and all the exhaust gas acts on the exhaust turbine 6T. Therefore, the acceleration response characteristic is significantly improved.

The control means 13 controls the operation of the entire system, and is basically a CPU, ROM and RA.
It is composed of an internal memory such as M and other peripheral devices and interfaces for input / output. This control means 13
Various signals such as engine speed, throttle opening, intake pressure (supercharging pressure) P1, intake temperature, etc. are input from sensors to control the opening ratios of the pressure control valve 11 and the flow control valve 12.

Next, the operation of this embodiment will be described with reference to the drawings. FIG. 2 is a diagram showing the relationship between the control states of the pressure control valve 11 and the flow rate control valve 12 and the boost pressure. FIG. 2 shows that the supercharging pressure gradually increases from the non-supercharging state, goes through the acceleration state, and then becomes the steady supercharging state, and the supercharging pressure gradually decreases from the steady supercharging state, then goes through the deceleration state and becomes non-supercharging. The opening state of each valve before returning to the state is shown. 2, region 1 shows a case where the intake air pressure (intake pressure) P1 of the engine is sufficiently supercharged and is close to the target supercharging pressure, and region 2 shows that the intake air pressure P1 of the engine is not It shows the case of a supercharging state, a supercharging pressure increasing state (accelerating state) during vehicle acceleration, and a supercharging pressure decreasing state (deceleration state) during vehicle deceleration.

First, in the non-supercharging state and the accelerating state, the flow rate control valve 12 is in the fully closed state. Therefore, the pressure control valve 11
Since it does not affect the intake pressure of the pressure chamber P regardless of the value of the opening, the opening in the present embodiment is an indefinite region, and the opening is approximately halfway between the full opening and the full opening. To do. Next, when the vehicle accelerates, the boost pressure gradually increases,
Enter area 1. At this point, the flow rate control valve 12 is opened from the fully closed state to the intermediate opening degree, and the pressure control valve 11 is fully opened from the intermediate opening degree. Then, the exhaust bypass valve 8W is opened from the fully closed state to the intermediate opening degree by the actuator 10 as the opening degree of the flow rate control valve 12 and the pressure control valve 11 is changed. As a result, part of the exhaust gas discharged from the exhaust pipe 5 bypasses the exhaust bypass pipe 8 and is discharged, and the supercharging pressure settles to a constant value within the region 1.

When the vehicle decelerates from the steady supercharging state (where the supercharging pressure exists in the region 1), the supercharging pressure gradually decreases and enters the region 2. At this point in time, the amount of exhaust gas discharged from the engine has decreased, so the openings of the flow rate control valve 12, the pressure control valve 11 and the exhaust bypass valve 8W may have any values. Therefore, the flow rate control valve 12 is fully closed from the intermediate opening degree, and the pressure control valve 11 returns from the fully opened state to the opening degree in the indefinite region (intermediate opening degree). On the other hand, the exhaust bypass valve 8W is also fully closed.

FIG. 3 shows a flow control valve 12 and a pressure control valve 11.
5 is a diagram showing how the intake air pressure P1 in a region 1 changes in accordance with the opening degree of. In the figure, the working pressure indicates the pressure value of the pressure chamber P of the actuator 10. At time t0, the flow control valve 12 and the pressure control valve 11
Are both intermediate openings. Therefore, the operating pressure is Pc and the supercharging pressure is P1c.

At time t1, only the pressure control valve 11 is fully opened while the flow rate control valve 12 remains at the intermediate opening. Then, the operating pressure decreases to Pd, and the supercharging pressure increases to P1b. Conventionally, since the supercharging pressure was controlled only by the pressure control valve 11, the supercharging pressure could only be increased up to this point.
However, in the present invention, the supercharging pressure can be further increased by changing the opening degree of the flow rate control valve 12.

That is, at time t2, the pressure control valve 11
Is fully opened, and the opening degree of the flow control valve 12 is set at time t0 ≦ t
Change from the intermediate opening at t2 to the fully closed side. Then, since the operating pressure is reduced to Pe, the bypass amount by the exhaust bypass valve 8W is reduced, the exhaust gas from the exhaust pipe 5 acting on the exhaust turbine 6T is increased, and the supercharging pressure is P1.
The maximum boost pressure P1a larger than b is increased. Then, when the flow rate control valve 12 becomes the intermediate opening degree at the time t3 and the pressure control valve 11 becomes the intermediate opening degree at the time t4, the working pressure and the supercharging pressure become the same values as at the time t0.

At time t5, only the pressure control valve 11 is fully closed while the flow control valve 12 remains at the intermediate opening. Then, the operating pressure rises to Pb and the supercharging pressure decreases to P1c. Conventionally, since the supercharging pressure was controlled only by the pressure control valve 11, the supercharging pressure could only be reduced up to this point.
However, in the present invention, the supercharging pressure can be further reduced by changing the opening degree of the flow control valve 12.

That is, at time t6, the pressure control valve 11
Remains fully closed, the flow control valve 12 is fully opened. Then, since the operating pressure rises to the supercharging pressure, the exhaust bypass valve 8W is fully opened, the amount of exhaust gas bypassing from the exhaust pipe 5 to the exhaust bypass pipe 8 is increased, and the supercharging pressure is smaller than P1d. Reduced to supply pressure P1e. Then, time t7
When the pressure control valve 11 becomes the intermediate opening degree at and the flow rate control valve 12 becomes the intermediate opening degree at the time t8, the working pressure and the supercharging pressure become the same values as those at the time t0. As described above, according to the present embodiment, the change range of the supercharging pressure can be increased as compared with the conventional case where the pressure control valve 11 alone is used for control.

When the exhaust turbine housing, which is a component of the supercharger, is replaced for the purpose of improving the engine output and its characteristics, the specifications of the exhaust bypass pipe in supercharging pressure control are changed. The Rukoto. That is,
In FIG. 1, when the passage cross-sectional area of the exhaust bypass pipe 8 becomes large, the operating pressure of the actuator 10 is the same and the opening degree of the exhaust bypass valve is also the same. However, since the passage cross-sectional area of the exhaust bypass pipe 8 is enlarged, the amount of exhaust gas that bypasses the exhaust bypass pipe 8 increases, so the supercharging pressure becomes smaller than the target supercharging pressure.

At this time, the operating pressure of the actuator 10 may be reduced, but when the opening of the pressure control valve 11 is already fully open, the operating pressure of the actuator 10 can no longer be reduced. Therefore, as at time t2 in FIG. 3, the pressure control valve 11 remains fully open, and the opening degree of the flow rate control valve 12 is changed from the intermediate opening degree at time t0 ≦ t <t2 to the fully closed side. Then, since the operating pressure is reduced to Pe, the opening degree of the exhaust bypass valve 8W is reduced, the exhaust gas from the exhaust pipe 5 acting on the exhaust turbine 6T is increased, and the supercharging pressure is increased. As described above, according to the present embodiment, the supercharging pressure is controlled to a desired value even when the exhaust turbine housing, which is a component of the supercharger, is replaced for the purpose of improving the engine output and its characteristics. Therefore, it is possible to reduce the labor and cost when developing and improving the engine. Further, according to the present embodiment, the acceleration performance of the vehicle is improved, so that the drivability is dramatically improved.

In the above-described embodiment, the case where the flow rate control valve is provided in the pressure guiding pipe between the pressure control valve and the intake compressor has been described, but the present invention is not limited to this, and the pressure control valve and the actuator may be provided between the pressure control valve and the actuator. It may be provided. Also in this case, the flow rate control valve may be fully closed in the process of increasing the boost pressure (acceleration operation state). Further, the flow rate control valve may be provided on both the compressor side and the turbine side.

[0028]

As described above, according to the present invention, there is an effect that the supercharging pressure can be quickly increased even in the process of increasing the supercharging pressure.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a supercharging pressure control system of the present invention.

FIG. 2 is a diagram showing a relationship between a control state of a pressure control valve and a flow rate control valve of FIG. 1 and a boost pressure.

FIG. 3 is a diagram showing how the intake air pressure changes within a region according to the openings of the pressure control valve and the flow rate control valve of FIG.

[Explanation of reference symbols] 1 engine 1A intake manifold 1B exhaust manifold 2 air cleaner 3 intake pipe 4 intercooler 5 exhaust pipe 6 turbocharger 6C intake compressor 6T exhaust turbine 7 throttle chamber 8 exhaust bypass pipe 8W exhaust bypass valve 9A, 9B pressure guide pipe 9C Branch pipe 10 Actuator P Pressure chamber D Diaphragm S Spring A Atmospheric pressure chamber 11 Pressure control valve 12 Flow control valve 13 Control means

Claims (1)

[Claims] 1. A supercharger comprising an intake compressor and an exhaust turbine, an exhaust bypass valve for adjusting the amount of exhaust gas supplied to the exhaust turbine of the supercharger, and the exhaust bypass valve according to the atmospheric pressure of a pressure chamber. An actuator that drives a pressure guide pipe that guides the downstream intake air of the intake compressor to the pressure chamber, and a pressure control that is branched and connected to the pressure guide pipe to control the pressure of the downstream intake air that is guided to the pressure chamber. A supercharging pressure control system comprising: a means and a flow rate control means for controlling a flow rate of the downstream side intake air flowing into the pressure guiding pipe.