JP2005140077A - Exhaust bypass valve control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust bypass valve control device for activating an exhaust gas purifying catalyst in an early stage by keeping an exhaust bypass valve into a fully opened condition to efficiently guide exhaust gas to the catalyst during warm-up operation right after cold start and for controlling the slight opening/closing of the exhaust bypass valve by keeping a negative pressure chamber into a closed condition between the negative pressure chamber and the atmospheric air during normal operation, with an actuator having improved reliability to the high temperature heat of a turbocharger. <P>SOLUTION: A control means 3 controls a diaphragm actuator 30 to perform the opening/closing operation of the exhaust bypass valve 24 in response to turbocharged pressure introduced into a positive pressure chamber 31, in such a manner that, in a period right after cold start when the exhaust gas purifying catalyst is in a non-activated condition, negative pressure is introduced into the negative pressure chamber 32 to open the exhaust bypass valve 24, and in a region where engine operated conditions are higher than a preset engine load, the negative pressure chamber 32 is kept into the closed condition between the negative pressure chamber 32 and the atmospheric air. The control means puts the negative pressure chamber 32 into the opened condition between itself and the atmospheric air in a region where the engine operated conditions are lower than the preset engine load. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exhaust bypass valve control device that performs opening / closing operation control of an exhaust bypass valve provided in an exhaust bypass path of an internal combustion engine with a turbocharger.

  2. Description of the Related Art Conventionally, a turbocharger that rotates a turbine with exhaust gas to move a supercharger is known as a means for obtaining a high output even with a small displacement internal combustion engine. Such a turbocharger usually has an exhaust bypass passage upstream of the turbine and is provided in the exhaust bypass passage because the turbocharging pressure may increase more than necessary under the high speed and high load condition and may damage the internal combustion engine. The supercharging pressure is controlled to an appropriate level by opening and closing the exhaust bypass valve (see, for example, Patent Document 1).

  By the way, in recent years, in the environment surrounding automobiles, exhaust gas regulations have been strengthened in various countries in response to the demand for environmental protection. Normally, exhaust gas discharged from a cylinder of an internal combustion engine is purified by an exhaust gas purification catalyst and discharged to the atmosphere. However, in an internal combustion engine with a turbocharger, the exhaust gas discharged from the cylinder is a turbine of the turbocharger. Since heat is taken away in the process of passing through the exhaust gas etc., there is a problem that the exhaust gas purification catalyst cannot be activated at an early stage.

  For this reason, in the prior art, until the exhaust gas purification catalyst reaches a predetermined catalyst activation temperature, the exhaust bypass valve provided in the exhaust bypass passage is opened and the exhaust gas is purified by bypassing the turbine. The catalyst is guided to the catalyst, and the temperature of the catalyst is positively controlled to activate the catalyst at an early stage (see, for example, Patent Document 2).

  The opening / closing operation of the exhaust bypass valve is usually performed by a diaphragm actuator. Such a diaphragm type actuator is provided in one chamber (negative pressure chamber) in which a diaphragm that partitions a case into two chambers, a rod that is connected to the diaphragm and drives the bypass valve, and closes the bypass valve. And a spring for urging the diaphragm to move the rod.

  When the exhaust gas purification catalyst is activated early during the warm-up operation, the negative pressure accumulated in the negative pressure chamber, for example, is supplied to the negative pressure chamber of the actuator to fully open the exhaust bypass valve. Then, the rod is moved against the spring force of the spring provided in the negative pressure chamber.

  When the supercharging pressure is controlled to an appropriate level by the exhaust bypass valve, a supercharging pressure pressurized by a compressor connected coaxially with the turbine is introduced into the other chamber (positive pressure chamber) of the actuator. The exhaust bypass valve is opened and closed in accordance with the balance between the introduced supercharging pressure and the force of the spring that urges the diaphragm (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 9-228848 JP 2002-364503 A Japanese Utility Model Publication No. 5-78934

  However, in order to quickly activate the exhaust gas purification catalyst during warm-up operation, it is necessary to efficiently lead the exhaust gas to the catalyst with the exhaust bypass valve fully opened, and in this case, the rod movement amount of the actuator is The longest.

  On the other hand, when controlling the supercharging pressure to an appropriate level during normal operation after the warm-up operation, the supercharging pressure is controlled by opening and closing the exhaust bypass valve in a smaller area than during the warm-up operation. In this case, the rod movement amount of the actuator is shorter than that during the warm-up operation.

  Further, as described above, the force required to open the exhaust bypass valve is a value determined by the spring force of the spring that biases the diaphragm.

  Therefore, a negative pressure accumulated in the negative pressure chamber, which is lower than the supercharging pressure introduced into the positive pressure chamber of the actuator, is introduced into the negative pressure chamber so that the exhaust bypass valve is fully opened. If the spring force is set to the value, the pressure gradient of the actuator determined by the movement amount of the actuator and the introduction pressure becomes small, and it becomes difficult to perform minute opening / closing control of the exhaust bypass valve during supercharging pressure control during normal operation. .

  The present invention solves the above-mentioned problems of the prior art, and at the time of warm-up operation, the exhaust bypass valve is fully opened to efficiently lead exhaust gas to the catalyst, and the exhaust gas purification catalyst is activated at an early stage. During operation, the negative pressure chamber is closed between the negative pressure chamber and the atmosphere so that the negative pressure chamber has an air damper effect, and the amount of movement of the actuator and the supercharging introduced into the positive pressure chamber An object of the present invention is to provide an exhaust bypass valve control device that increases the pressure gradient of the actuator determined by the pressure and enables minute opening / closing control of the exhaust bypass valve.

  It is another object of the present invention to provide an exhaust bypass valve control device that solves the above-described problems and improves the reliability of the actuator against high heat of the turbocharger.

  In order to achieve the above object, in the exhaust bypass valve control device of the present invention, in the exhaust bypass valve control device that controls the opening / closing operation of the exhaust bypass valve provided in the exhaust bypass passage that bypasses the turbine rotor of the turbocharger. A diaphragm actuator having a positive pressure chamber and a negative pressure chamber partitioned by a diaphragm, and performing an opening / closing operation of the exhaust bypass valve, and a period in which the exhaust gas purification catalyst immediately after a cold start is in an inactive state, In addition to opening the exhaust bypass valve by introducing negative pressure into the negative pressure chamber, the negative pressure chamber is closed between the negative pressure chamber and the atmosphere in a region where engine operating conditions are higher than a predetermined engine load. The diaphragm actuator is controlled so as to open and close the exhaust bypass valve in accordance with the supercharging pressure introduced into the positive pressure chamber. Characterized by comprising a means.

  According to a preferred aspect of the present invention, the control means opens the space between the negative pressure chamber and the atmosphere in a region where the engine operating condition is lower than a predetermined engine load.

  As described above, according to the exhaust bypass valve control device of the present invention, during the warm-up operation, the exhaust bypass valve is fully opened to efficiently lead the exhaust gas to the catalyst, thereby activating the exhaust gas purification catalyst at an early stage. In addition, it is possible to provide an exhaust bypass valve control device that enables minute opening / closing control of the exhaust bypass valve during normal operation.

  Furthermore, it is possible to provide an exhaust bypass valve control device that improves the reliability of the actuator against the high heat of the turbocharger.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

  FIG. 1 is a diagram illustrating an internal combustion engine with a turbocharger and an exhaust bypass valve control device that controls the opening / closing operation of an exhaust bypass valve provided in the exhaust bypass path thereof.

  As shown in FIG. 1, in the internal combustion engine 1, an intake pipe 12 and an exhaust pipe 13 are connected to a cylinder 11, and a turbocharger 2 is disposed between the intake pipe 12 and the exhaust pipe 13 so as to straddle the intake pipe 12 and the exhaust pipe 13. The compressor rotor 21 and the turbine rotor 22 of the turbocharger 2 are connected and fixed by a shaft. Further, an exhaust gas purification catalyst (hereinafter referred to as “catalyst”) (not shown) is disposed downstream of the turbocharger 2 of the exhaust pipe 13.

  Further, the exhaust pipe 13 is provided with an exhaust bypass passage 23 through which exhaust flows from the upstream to the downstream of the turbine rotor 22, and an exhaust bypass valve 24 is attached to the exhaust bypass passage 23 so as to be freely opened and closed. A rod 34 provided in the diaphragm actuator 30 is connected to the exhaust bypass valve 24.

  The opening / closing operation control of the exhaust bypass valve 24 is performed by the exhaust bypass valve control device 3 that responds to the supercharging pressure by the compressor rotor 21 and the negative pressure by the negative pressure generating means.

  The exhaust bypass valve control device 3 is introduced from a diaphragm actuator 30 that opens and closes the exhaust bypass valve 24 and a supercharging pressure that branches from the intake pipe 12 downstream of the compressor rotor 21 and introduces a supercharging pressure to the diaphragm actuator 30. The negative pressure chamber 50 which is a negative pressure generating means for accumulating the negative pressure generated by the gas flow in the pipe 40 and the intake pipe 12, the negative pressure chamber 50, or the introduction pipe 60 for introducing the atmospheric pressure into the diaphragm actuator 30, the diaphragm actuator The control valve 70 and the control valve 80 are provided as control means for controlling the pressure introduced to the pressure 30.

  A check valve 90 is provided between the negative pressure chamber 50 and the intake pipe 12 of the exhaust bypass valve control device 3 so that gas flows only from the negative pressure chamber 50 to the intake pipe 12.

    2 and 3 are a sectional view and a partially enlarged sectional view of the diaphragm actuator 30. FIG. In FIG. 2, the lower half shows a state where the rod 34 is extended.

  As shown in FIG. 2, the diaphragm actuator 30 is divided into a positive pressure chamber 31 and a negative pressure chamber 32 by a diaphragm 33 inside the housing of the actuator 30. The diaphragm 33 is interposed between the diaphragm retainers 37a and 37b. A rod 34 is fixed to the center of the diaphragm 33 and the diaphragm retainers 37a and 37b. Further, the diaphragm 33 and the diaphragm retainers 37 a and 37 b are biased toward the positive pressure chamber 31 by a spring 35 disposed in the negative pressure chamber 32. The rod 34 is pivotally supported by a rod bearing 38 disposed on the surface of the negative pressure chamber 32 facing the diaphragm 33 so as to be slidable in the axial direction. Further, a positive pressure introduction hole 31a and a negative pressure introduction hole 32a are formed in the positive pressure chamber 31 and the negative pressure chamber 32, respectively. Such a diaphragm actuator 30 is attached to a predetermined position of the turbocharger 2 by a bracket 36 formed on the housing of the actuator 30.

  As shown in FIG. 3, the rod bearing 38 includes a rod seal 38 a that ensures the airtightness of the negative pressure chamber 32, a bearing 38 b that guides the sliding in the axial direction of the rod 34, an under that accommodates the rod seal 38 a and the bearing 38 b. A plate 38c and a bearing retainer 38d are provided. A plate 38f is disposed between the under plate 38c and the bearing retainer 38d.

  The materials of the diaphragm 33, the rod seal 38a, and the bearing 38b are selected in consideration of the heat generated by the turbocharger 2, respectively. Accordingly, it is desirable that the diaphragm 33 is made of fluorosilicone rubber, hydrin rubber or the like, the rod seal 38a is made of fluorosilicone rubber, fluororubber or the like, and the bearing 38b is made of fluororesin, 66 nylon or the like.

  Next, the operation of the exhaust bypass valve control device 3 will be described with reference to FIG.

[When warming up (when starting the engine)]
During a period in which the catalyst immediately after the cold start of the internal combustion engine 1 is in an inactive state, a catalyst (not shown) arranged downstream of the turbocharger 2 is provided in the exhaust bypass passage 23 until a predetermined catalyst activation temperature is reached. It is necessary to open the exhaust bypass valve 24 and bypass the turbine 22 to guide the exhaust gas to a catalyst (not shown), to positively control the temperature of the catalyst to activate the catalyst at an early stage.

  In this case, the exhaust bypass valve 24 is fully opened to enable early activation of the catalyst with the maximum amount of exhaust that bypasses the turbine 22. In the present embodiment, the rod 34 of the diaphragm actuator 30 is extended to the maximum, so that the exhaust bypass valve 24 is fully opened.

  In order to fully open the exhaust bypass valve 24, the negative pressure accumulated in the negative pressure chamber 50 is introduced into the negative pressure chamber 32 of the actuator 30 to resist the spring force of the spring 35 provided in the negative pressure chamber 32. Then, the rod 34 is moved.

  Here, in order to introduce the negative pressure accumulated in the negative pressure chamber 50 into the negative pressure chamber 32, the electromagnetic direction control valve 80 is turned on and the electromagnetic direction control valve 70 is turned off. And the introduction pipe 60 are communicated with each other. In this state, the negative pressure accumulated in the negative pressure chamber 50 is introduced into the negative pressure chamber 32, and the diaphragm 33 in the actuator 30 moves in the direction in which the rod 34 is extended.

  In the present embodiment, the closing load of the exhaust bypass valve 24 by the spring 35 in the actuator 30 is appropriately set corresponding to the maximum value of the negative pressure accumulated in the negative pressure chamber 50. Then, when the maximum value of the negative pressure accumulated in the negative pressure chamber 50 acts on the negative pressure chamber 32, the rod 34 is extended to the maximum, and the exhaust bypass valve 24 is fully opened.

[During normal operation (normal driving)]
During normal operation after the warm-up operation when the catalyst reaches a predetermined catalyst activation temperature, that is, in a region where engine operating conditions are higher than a predetermined engine load, the supercharging pressure by the turbocharger 2 exceeds an appropriate value. When the exhaust pressure is increased, the exhaust bypass valve 24 is opened and closed in a region smaller than that during the warm-up operation to control the supercharging pressure to an appropriate level. In the present embodiment, the extension amount of the rod 34 at this time is set to an extension amount that is about a quarter of the maximum extension amount.

Here, in the present embodiment, the engine operating condition is determined by determining the engine load based on the accelerator opening and the engine speed, and a predetermined range that is during normal travel in a region exceeding the predetermined accelerator opening and the engine speed. And the exhaust bypass valve control device 3 is controlled. Further, the valve opening timing and valve opening amount of the exhaust bypass valve 24 are determined by the pressure gradient of the actuator 30 determined by the amount of movement of the rod 34 and the supercharging pressure introduced into the positive pressure chamber 31.

  In order to open and close the exhaust bypass valve 24 for the purpose of controlling the supercharging pressure, the supercharging pressure is introduced into the positive pressure chamber 31 of the actuator 30 from the supercharging pressure introduction pipe 40 and the diaphragm 33 in the actuator 30 is pressed. Then, the rod 34 is extended.

  By the way, as described above, the closing load of the exhaust bypass valve 24 is determined by the pressure receiving area of the exhaust bypass valve and the exhaust pressure. When the negative pressure corresponding to the maximum negative pressure is introduced into the negative pressure chamber 32, the rod 34 is maximized. The spring force of the spring 35 that biases the diaphragm 33 so as to expand is determined. However, as it is, the pressure gradient of the actuator 30 is small, that is, the stroke amount of the actuator 30 is large with respect to the amount of change of the pressure applied to the actuator 30, so that it is compared with the negative pressure accumulated in the negative pressure chamber 50. Thus, during normal operation in which supercharging pressure control is performed with a high supercharging pressure, the rod 34 can be expanded and contracted within a range of about a quarter of the maximum extension amount to control the minute opening / closing operation of the exhaust bypass valve 24. It becomes difficult.

  Therefore, in the present embodiment, during normal operation, the negative pressure chamber 32 is closed between the negative pressure chamber 32 and the atmosphere, so that the air in the negative pressure chamber 32 has a damper effect, and the rod The pressure gradient of the actuator determined by the amount of movement 34 and the supercharging pressure introduced into the positive pressure chamber 31 is increased to enable minute opening / closing control of the exhaust bypass valve 24.

  Here, in order to close the negative pressure chamber 32 between the negative pressure chamber 32 and the atmosphere, the electromagnetic direction control valve 80 is turned off and the electromagnetic direction control valve 70 is turned on to introduce the introduction pipe. 60 and the atmosphere are closed. In this state, gas does not enter or exit from the negative pressure chamber 32, so that the negative pressure chamber 32 has a predetermined damper characteristic.

[When stopped or when the boost pressure is low]
When the catalyst stops at the end of warm-up after reaching the predetermined catalyst activation temperature, or when the supercharging pressure is low, that is, in a region where the engine operating conditions are lower than the predetermined engine load, the overcharge by the turbocharger 2 occurs. There is no fear that the supply pressure will increase beyond the appropriate value. On the other hand, since the actuator 30 attached to the turbocharger 2 is used under severely thermal conditions, the operational stability of the actuator 30 can be improved by reducing the pressure change in the negative pressure chamber due to the temperature rise. it can. In particular, it is effective to perform such control in the exhaust bypass valve control device 3 of the present embodiment that closes the negative pressure chamber 32 between the negative pressure chamber 32 and the atmosphere during normal traveling.

  The engine operating conditions are determined by determining the engine load as a predetermined engine load region based on the accelerator opening and the engine speed, as in the normal operation.

  Here, in order to make the negative pressure chamber 32 open to the atmosphere, the electromagnetic directional control valve 80 is turned off and the electromagnetic directional control valve 70 is turned off to open the space between the introduction pipe 60 and the atmosphere. And

  Table 1 summarizes the operation of the exhaust bypass valve control device 3.

  In the diaphragm type actuator 30 provided in the exhaust bypass valve control device 3 according to the present embodiment, the negative pressure chamber 32 of the actuator 30 is closed by performing the control according to Table 1, so that the pressure of the actuator 30 The gradient can be increased. Therefore, during a period in which the catalyst immediately after the cold start is in an inactive state, a negative pressure accumulated in the negative pressure chamber, for example, a negative pressure of about minus 40 KPa is introduced into the negative pressure chamber 32, and the extension amount of the actuator 30 is increased. The exhaust bypass valve is fully opened and the normal operation, that is, the region where the engine operating condition is higher than the predetermined engine load, for example, the pressure introduced into the positive pressure chamber 31 is 40 kPa or its In a pressure region exceeding the value, the actuator 30 can be expanded and contracted by an expansion / contraction amount that is about one-fourth of the maximum expansion amount, so that the minute opening / closing control of the exhaust bypass valve 24 can be performed.

FIG. 1 is a diagram showing an internal combustion engine with a turbocharger and an exhaust bypass valve control device according to the present embodiment. FIG. 2 is a cross-sectional view of the diaphragm actuator. FIG. 3 is a partially enlarged sectional view of the diaphragm actuator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Turbocharger 3 ... Exhaust bypass valve control device 22 ... Turbine rotor 23 ... Exhaust bypass passage 24 ... Exhaust bypass valve 30 ... Diaphragm actuator 31 ... Positive pressure chamber 32 ... Negative pressure chamber 33 ... Diaphragm 70 ... Electromagnetic Type directional control valve (control means)
80 ... Electromagnetic direction control valve (control means)

Claims (2)

In an exhaust bypass valve control device that performs opening / closing operation control of an exhaust bypass valve provided in an exhaust bypass path that bypasses a turbine rotor of a turbocharger,
A diaphragm actuator having a positive pressure chamber and a negative pressure chamber partitioned by a diaphragm, and performing an opening and closing operation of the exhaust bypass valve;
During a period in which the exhaust gas purification catalyst is in an inactive state immediately after a cold start, a negative pressure is introduced into the negative pressure chamber to open the exhaust bypass valve, and an engine operating condition is higher than a predetermined engine load. Then, the diaphragm type actuator is configured so that the negative pressure chamber is closed between the negative pressure chamber and the atmosphere, and the exhaust bypass valve is opened and closed according to the supercharging pressure introduced into the positive pressure chamber. An exhaust bypass valve control device comprising: control means for controlling the exhaust gas.   2. The exhaust bypass valve control device according to claim 1, wherein the controller opens the space between the negative pressure chamber and the atmosphere in a region where the engine operating condition is lower than a predetermined engine load.

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