JPH078553U - Exhaust Gas Recirculation Controller for Internal Combustion Engine with Variable Nozzle Turbocharger - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to simplify the structure and control of an exhaust gas recirculation control system in an internal combustion engine with a variable nozzle turbocharger. [Structure] It is judged whether or not it is an exhaust gas recirculation point (step 1), and if it is an exhaust gas recirculation point, the actuator for driving the movable nozzle vane is controlled so as to reduce the turbine nozzle opening smaller than during normal operation ( Step 2). If it is not the exhaust gas recirculation point, the actuator for driving the movable nozzle vane is controlled so that the turbine nozzle opening is normally controlled (step 3). in this way,
By controlling the turbine nozzle opening to a smaller value than during normal operation in a predetermined operating condition that requires exhaust gas recirculation, the intake passage internal pressure and exhaust passage internal pressure are reversed, and the intake passage internal pressure is greater than the exhaust passage internal pressure. It became so low that exhaust gas recirculation became possible.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an exhaust gas recirculation control device for an internal combustion engine with a variable nozzle turbocharger, and more particularly to a technique for simplifying the structure and control of an exhaust gas recirculation control system.

[0002]

[Prior art]

A so-called exhaust gas recirculation (EGR), which recirculates a part of exhaust gas into intake air, is known as a method of reducing nitrogen oxides (NO _x ) which is one of exhaust gas purification methods in an internal combustion engine. In the exhaust gas recirculation control device for an internal combustion engine with a turbocharger, conventionally, there is known a technique of controlling an exhaust gas recirculation control valve provided in an exhaust gas recirculation passage based on an engine load and an engine speed (actually, the engine speed is increased). No. 2-46057, Japanese Utility Model Laid-Open No. 2-34447 and Japanese Utility Model Laid-Open No. 2-43450).

In an internal combustion engine with a turbocharger, a turbine nozzle of an exhaust turbine is used in order to improve the output of the engine, reduce fuel consumption, improve mobility, etc. by varying the turbine capacity to control the intake air amount. It is known that a mechanism for changing the opening is provided (see Japanese Utility Model Laid-Open No. 63-154732). By the way, in an internal combustion engine with a turbocharger, the intake pressure after being compressed by the compressor of the turbocharger is higher than the exhaust pressure, so that at this time the intake flows back to the exhaust side, and exhaust gas recirculation may occur. Can not.

Therefore, for example, as shown in FIG. 6, normally, exhaust gas recirculation is possible in a region where the exhaust passage internal pressure is higher than the intake passage internal pressure, but the exhaust passage internal pressure is equal to the intake passage internal pressure. There is a problem that exhaust gas recirculation is impossible in a region of B lower than that, and the exhaust gas recirculation region is limited. Therefore, conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-47157, a bypass pipe and a switching valve are provided in the intake pipe, a venturi is provided in the bypass pipe, and exhaust gas recirculation is provided at the venturi portion. An exhaust gas recirculation control device for an internal combustion engine with a turbocharger has been proposed in which a pipe is opened to reduce the static pressure of intake air and suck exhaust gas.

[0005]

[Problems to be solved by the device]

 However, in such a conventional device, the venturi causes throttling loss when exhaust gas recirculation is not performed at the time of high load operation, etc.In order to avoid this, the bypass passage and the switching valve are provided as described above. Therefore, the structure is complicated and the weight of the device itself is increased.

[0006] The applicant of the present application has proposed a technique in Japanese Patent Application No. 4-2187 in which an intake pipe is provided with a throttle to deal with the conventional problem. Loss is inevitable. Further, the applicant of the present application, in Japanese Patent Application No. 4-65148, prevents the occurrence of the above throttling loss by opening the intake throttling mechanism with an actuator when exhaust gas recirculation is not performed during high load operation. However, the control structure becomes complicated as the structure becomes complicated due to the increase in the number of component parts.

The present invention has been made in view of the above, and it is possible to simplify the structure and control of an exhaust gas recirculation control system by using a variable nozzle mechanism that changes the turbine nozzle opening of an exhaust turbine. To aim.

[0008]

[Means for Solving the Problems]

 The present invention comprises a turbocharger having a variable nozzle mechanism for varying a turbine nozzle opening of an exhaust turbine, wherein an exhaust passage at an inlet of the exhaust turbine is connected to an intake passage through an exhaust gas recirculation passage, In an exhaust gas recirculation control device for an internal combustion engine with a variable nozzle turbocharger in which an exhaust gas recirculation control valve is provided in a recirculation passage, an engine operating condition detecting means for detecting an engine operating condition, and a detection output from the means. Control means for controlling the variable nozzle mechanism so as to reduce the turbine nozzle opening to a smaller value than in normal operation in a predetermined operating state that is an exhaust gas recirculation point based on a signal.

[0009]

[Action]

 In such a configuration, if the turbine nozzle opening is controlled to be smaller than that during normal operation in a predetermined operating state where exhaust gas recirculation is required, the intake passage internal pressure and the exhaust passage internal pressure are reversed, and the intake passage internal pressure is reduced. Exhaust gas recirculation becomes possible because the pressure becomes lower than the pressure, and the indispensable throttle valve, etc., which was conventionally installed in the intake passage, can be eliminated, and the structure and control of the exhaust gas recirculation control system of the internal combustion engine with turbocharger It can be simplified.

[0010]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, an exhaust manifold 2 is attached to the engine 1, and an exhaust turbine 5 of a turbocharger 4 is interposed in an exhaust pipe 3 connected to the exhaust manifold 2. An intake collector 6 is attached to the engine 1, and an intake compressor 8 of a turbocharger 4 is interposed in an intake pipe 7 connected to the intake collector 6.

The turbocharger 4 is provided with a variable nozzle mechanism that changes the turbine nozzle opening of the exhaust turbine 5. In this variable nozzle mechanism, for example, as shown in FIG. 2, a plurality of movable nozzle vanes 9 are provided in the exhaust gas flow direction of the exhaust turbine 5, and the movable nozzle vanes 9 are operated by an actuator (not shown) to open the turbine nozzle opening degree. A can be changed.

The actuator is controlled on the basis of the engine operating state detection signal by a control signal output from a control unit (not shown) to which an engine operating state detection signal such as an engine load signal and a rotation speed signal is input, and the turbine is controlled. The nozzle opening A is variably controlled according to the engine operating condition. For example, in the low speed and high load range where you want to increase the intake air amount, reduce the turbine nozzle opening A to make the turbine capacity "small" (see Fig. 2 (A)), and in the high speed range and partial load where you want to reduce the exhaust resistance. In the region, the nozzle vane opening A is increased and the turbine capacity is set to “large” (see FIG. 2 (B)) and used.

One end of an exhaust gas recirculation pipe 10 as an exhaust gas recirculation passage is connected to the exhaust pipe 3 at the inlet of the exhaust turbine 5, and the other end of the exhaust gas recirculation pipe 9 is connected to the intake collector 6. Has been done. An exhaust gas recirculation control valve 11 that controls the amount of exhaust gas recirculation is provided in the middle of the exhaust gas recirculation pipe 10. This exhaust gas recirculation control valve 11 is controlled by a control signal from a control unit to which an engine load signal and an engine speed signal, which are respectively output from an engine load sensor and an engine rotation sensor as engine operating state detecting means, are input. Control is performed based on the engine load signal and the rotation speed signal.

Based on the detection signals output from the engine load sensor and the engine rotation sensor, the turbine nozzle opening A can be reduced to a smaller value than in the normal operation in a predetermined operating state that is an exhaust gas recirculation point. Control means for controlling the actuator for driving the movable nozzle vane 9 in the nozzle mechanism is provided as software in the control unit.

The control contents of the control means are as shown in the flowchart of FIG. That is, in step 1 of the flowchart, it is determined whether or not the exhaust gas recirculation point is based on the engine load and the engine speed. If it is the exhaust gas recirculation point, the process proceeds to step 2 and the turbine nozzle opening A is set. The actuator for driving the movable nozzle vane 9 is controlled so as to narrow down the pressure smaller than during normal operation. On the other hand, if it is not the exhaust gas recirculation point, the routine proceeds to step 3, where the actuator for driving the movable nozzle vane 9 is controlled so as to normally control the turbine nozzle opening based on the engine load, engine speed, and the like.

The exhaust gas recirculation points are points A to C in the characteristic diagram of FIG. 4 showing the relationship between the engine load, the rotation speed, and the intake manifold pressure, for example. In such a configuration, when the turbine nozzle opening is controlled to be smaller than that during normal operation in a predetermined operating state where exhaust gas recirculation is required, the intake passage internal pressure and the exhaust passage internal pressure are reversed as shown in FIG. The pressure in the passage becomes lower than the pressure in the exhaust passage, and exhaust gas recirculation becomes possible. In FIG. 5, when the turbine nozzle opening A is controlled to be smaller at the exhaust gas recirculation points a to d than during normal operation, exhaust gas recirculation is possible at this point.

As described above, with a simple configuration in which the mechanism for controlling the variable nozzle mechanism in association with the exhaust gas recirculation control is added, the exhaust gas recirculation can be performed even in the exhaust gas recirculation impossible region, and the static pressure of the intake air can be reduced. Adopting a bypass pipe and a switching valve in the intake pipe to ventilate the exhaust gas recirculation gas, a venturi in the bypass pipe, a throttle in the intake pipe, and an actuator that opens the intake throttle mechanism It is not necessary to do so, and the structure can be simplified by reducing the number of component parts and the control structure can be simplified.

As described above, the present invention has been described with reference to the specific embodiments, but the present invention is not limited thereto, and is attached to the present invention by a person skilled in the art. It should be noted that various changes and modifications can be made without departing from the scope of the utility model registration claim.

[0019]

[Effect of device]

 As described above, the present invention is directed to an exhaust gas recirculation control system for a variable nozzle turbocharged internal combustion engine, in which a turbine is operated in a predetermined operating state, which is an exhaust gas recirculation point, based on a detection signal output from an engine operating state detecting means. Since the variable nozzle mechanism is configured to control the nozzle opening to be smaller than that during normal operation, even if the exhaust gas recirculation region where the pressure in the intake passage is higher than the pressure in the exhaust passage cannot be recirculated from the exhaust passage to the intake passage. The exhaust gas recirculation can be performed, the exhaust gas recirculation region can be expanded, and the structure can be simplified by reducing the number of constituent parts, and the control structure can be simplified, which is a practical effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an exhaust gas recirculation control device for an internal combustion engine with a variable nozzle turbocharger according to the present invention.

FIG. 2 is a schematic cross-sectional view showing a variable nozzle mechanism in the above embodiment.

FIG. 3 is a flowchart for explaining the control contents of the control means of the above embodiment.

FIG. 4 is a characteristic diagram illustrating an exhaust gas recirculation point in the above embodiment.

FIG. 5 is a characteristic diagram illustrating an exhaust gas recirculation possible region in the above embodiment.

FIG. 6 is a characteristic diagram for explaining a conventional exhaust gas recirculation possible region and an impossible exhaust gas recirculation region.

[Explanation of symbols]

 1 engine 3 exhaust pipe 4 turbocharger 5 exhaust turbine 7 intake pipe 8 intake compressor 9 movable nozzle vane 10 exhaust gas recirculation pipe 11 exhaust gas recirculation control valve

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area F02M 25/07 550 Q

Claims (1)

[Scope of utility model registration request] 1. A turbocharger having a variable nozzle mechanism for varying a turbine nozzle opening of an exhaust turbine,
An exhaust gas recirculation control device for an internal combustion engine with a variable nozzle turbocharger, wherein an exhaust gas recirculation passage is connected to an exhaust gas passage of an exhaust turbine inlet through an exhaust gas recirculation passage, and an exhaust gas recirculation control valve is interposed in the exhaust gas recirculation passage. In the engine operating state detecting means for detecting the operating state of the engine, and the turbine nozzle opening is narrowed to a smaller value than in the normal operating state in a predetermined operating state which is an exhaust gas recirculation point based on a detection signal output from the means. An exhaust gas recirculation control device for an internal combustion engine with a variable nozzle turbocharger, comprising: a control means for controlling the variable nozzle mechanism.