JP2008267285A - Cooling control device for butterfly type exhaust throttle valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling control device for butterfly type exhaust throttle valve not disturbing normal behavior even if the same is exposed to high temperature exhaust gas. <P>SOLUTION: An exhaust emission control device for an internal combustion engine provided with an exhaust emission control filter 132 installed in an exhaust gas passage 122 of the internal combustion engine, and the butterfly type exhaust throttle valve 134 provided on a downstream side thereof, is provided with a circulation channel 140 communicating to a through hole 134 C formed on a valve shaft 134B of the exhaust throttle valve and circulating cooling water of the internal combustion engine, and a water quantity adjusting valve 142 provided in the circulation channel. The device is provided with a control means controlling opening of the water quantity adjusting valve 142 to make cooling water of predetermined quantity to the through hole 134B during regeneration of the exhaust emission control filter. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cooling control device for a butterfly type exhaust throttle valve, and in particular, an internal combustion engine provided with an exhaust purification filter installed in an exhaust passage of an internal combustion engine, and a butterfly type exhaust throttle valve disposed downstream of the exhaust purification filter. The present invention relates to a cooling control device for a butterfly type exhaust throttle valve in an exhaust purification device of an engine.

  In general, in an internal combustion engine, particularly a diesel engine, removal of particulate matter (particulate matter, hereinafter referred to as PM) contained in exhaust gas is an important issue. For this reason, there is a technique for providing an exhaust purification filter (for example, diesel particulate filter, hereinafter also referred to as DPF) for collecting particulate matter in the exhaust system of the internal combustion engine so that particulate matter is not released into the atmosphere. .

  In this DPF, if the amount of accumulated PM is excessive, the filter is clogged, and there is a possibility that the fuel consumption is deteriorated due to the output reduction resulting from this, or the filter is damaged. Therefore, as a technique for removing such clogging, a butterfly type exhaust throttle valve is provided in the exhaust passage of the internal combustion engine, and the exhaust gas temperature is increased by reducing the flow rate of the exhaust gas to increase the exhaust pressure, thereby regenerating the DPF. Technology is known.

  By the way, such a butterfly type exhaust throttle valve receives a thermal load due to high-temperature exhaust gas, so that the bushing supporting the valve shaft exceeds the heat resistance limit, and normal operation of the butterfly type exhaust throttle valve may be difficult. There is.

  In response to this, Patent Document 1 discloses a valve body that is installed in a pipe body through which a high-temperature fluid flows, and that has a valve shaft (valve shaft), and is disposed on the side of the pipe body to support the valve shaft. There is disclosed a technique for forming an on-off valve structure having a bush and forming a refrigerant passage through which a refrigerant such as air or cooling water flows between the tube body and the bush.

JP 2006-77901 A

  However, although the technique described in Patent Document 1 can suppress the heat of the high-temperature exhaust gas flowing through the pipe from being transmitted to the bush and reduce the risk of breakage, the fuel for regenerative combustion is added. When the temperature of the exhaust gas flowing around the exhaust throttle valve becomes even higher, such as during regeneration of the exhaust purification filter, it is not sufficient to suppress the transfer of heat to the bush. Variation occurs in the control of the opening degree or the closing degree. This is presumed to be due to distortion of the valve shaft of the butterfly type exhaust throttle valve and hindering the normal behavior of the valve. As a result, it has been found that control of temperature and pressure in the exhaust purification filter becomes unstable, resulting in deterioration of fuel consumption and torque fluctuation of the internal combustion engine.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a cooling control device for a butterfly-type exhaust throttle valve that does not hinder normal behavior even when exposed to high-temperature exhaust gas. There is to do.

  A cooling control device for a butterfly type exhaust throttle valve according to an embodiment of the present invention that achieves the above object includes an exhaust purification filter installed in an exhaust passage of an internal combustion engine, and a butterfly arranged downstream of the exhaust purification filter. In the exhaust gas purification apparatus for an internal combustion engine provided with a type exhaust throttle valve, a circulation path that communicates with a through hole formed in a valve shaft of the exhaust throttle valve and circulates cooling water of the internal combustion engine, and is provided in the circulation path. And a control means for controlling the opening degree of the water amount adjusting valve so that a predetermined amount of cooling water flows through the through hole when the exhaust purification filter is regenerated.

  According to the above configuration, at the time of regeneration of the exhaust purification filter, the cooling water of the internal combustion engine is circulated to the through hole from the circulation path communicated with the through hole formed in the valve shaft of the butterfly type exhaust throttle valve. And the opening degree of the water quantity adjustment valve provided in the circulation path | route is controlled by the control means, and the circulating cooling water is made into predetermined amount. Therefore, since a predetermined amount of cooling water is circulated through the through hole formed in the valve shaft, the valve shaft is prevented from being distorted and the normal behavior of the valve is not hindered. Thus, deterioration of the fuel consumption of the internal combustion engine is suppressed, and torque stability is also improved.

  Here, it is preferable that when the temperature of the cooling water exceeds a predetermined value, the control means performs control so as to reduce the opening of the water amount adjustment valve in accordance with the temperature.

  According to this configuration, since the circulation amount is limited, it is possible to avoid overheating of the internal combustion engine due to an excessive rise in the temperature of the cooling water.

  Further, the control means may perform control so that the opening of the water amount adjustment valve is fully opened when the internal combustion engine is started at a low temperature.

  In this way, when the internal combustion engine is started at a low temperature, the amount of cooling water circulated through the through hole formed in the valve shaft is increased and heated by the exhaust gas, so that warming up of the internal combustion engine is promoted. Thus, emission reduction and misfire are suppressed.

  Further, the control means may perform control so that the opening of the water amount adjustment valve is fully opened when the internal combustion engine is started at a high altitude.

  In this way, when the internal combustion engine is started at a high altitude, the amount of cooling water circulated through the through hole formed in the valve shaft is increased and heated by the exhaust gas, so that warming up of the internal combustion engine is promoted. Thus, emission reduction and misfire are suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram illustrating a schematic configuration of an embodiment in which the present invention is applied to an automobile diesel engine.

  In FIG. 1, 100 is a diesel engine body, 102 is an intake passage of the engine 100, 104 is a surge tank provided in the intake passage 102, and 106 is an intake branch pipe connecting the surge tank 104 and the intake port of each cylinder. .

  In the present embodiment, the intake passage 102 is provided with an intake throttle valve 108 that restricts the flow rate of intake air flowing through the intake passage 102 and an intercooler 110 that cools intake air. The intake throttle valve 108 includes an actuator 108A of an appropriate type such as a solenoid or a vacuum actuator, and takes an opening degree according to a control signal from an electronic control unit (ECU) 200 described later. In the present embodiment, the intake throttle valve 108 reduces the intake pressure, for example, at the time of low engine rotation, and increases the amount of exhaust gas (EGR gas) that returns to the surge tank 104 through the EGR passage 152 described later. Used.

  In FIG. 1, an air flow meter 112 is provided near the intake inlet of the intake passage 102. In the present embodiment, the air flow meter 112 is of a type that can measure the mass flow rate of the intake air flowing through the intake passage 102, such as a hot-wire flow meter. After the air flowing into the intake passage 102 passes through the air flow meter 112, it is pressurized by the compressor 130C driven by the turbine 130T of the turbocharger 130, cooled by the intercooler 110 provided in the intake passage 102, and then the surge tank 104. Then, it is sucked into each cylinder through the branch pipe 106.

  Reference numeral 114 in FIG. 1 denotes a fuel injection valve that directly injects fuel into each cylinder. The fuel injection valve 114 is connected to a common pressure accumulation chamber (common rail) 116 that stores high-pressure fuel. The fuel of the engine 100 is boosted by a high-pressure fuel pump (not shown), supplied to the common rail 116, and directly injected into each cylinder from the common rail 116 through each fuel injection valve 114.

  Further, reference numeral 120 in FIG. 1 is an exhaust manifold that connects the exhaust port of each cylinder and the exhaust passage 122, and the turbocharger 130 described above is disposed downstream thereof. As described above, the turbocharger 130 includes the exhaust turbine 130T driven by the exhaust gas in the exhaust passage 122 and the intake compressor 130C driven by the exhaust turbine 130T.

  In the present embodiment, a DPF 132 including a catalyst (for example, a three-way catalyst) is disposed in the exhaust passage 122 on the downstream side of the turbocharger 130, and an exhaust flow for controlling the exhaust flow rate flowing through the exhaust passage 122 downstream thereof is controlled. A butterfly type exhaust throttle valve 134 is disposed. The exhaust throttle valve 134 includes an actuator 134A, similar to the intake throttle valve 108, and takes a fully open position and a closed position with a predetermined opening according to a control signal from the ECU 200. In the present embodiment, the exhaust throttle valve 134 is used when raising the exhaust temperature for early activation of the catalyst and regeneration of the DPF 132.

  Further, in the present embodiment, as shown in FIG. 2, the valve shaft 134B of the butterfly type exhaust throttle valve 134 is communicated with a through hole 134C formed through the axis to circulate the cooling water of the engine 100. A circulation path 140 is provided. The circulation path 140 is connected to be branched from a cooling passage in the engine 100, for example, in a cylinder head and returned to the cooling passage in the cylinder block, and a water amount adjustment valve 142 is provided in the middle thereof. . The water amount adjustment valve 142 is also provided with an actuator 134A, and its opening degree is controlled in accordance with a control signal from the ECU 200.

  In the present embodiment, an EGR device 150 that recirculates part of the engine exhaust to the intake system is provided. The EGR device 150 includes the EGR passage 152 that connects the exhaust manifold 120 and the intake surge tank 104, an EGR control valve (hereinafter referred to as an EGR valve) 154 disposed in the EGR passage 152, and an upstream side of the EGR valve 154. The EGR cooler 156 provided in the EGR passage 152 is provided. The EGR valve 154 includes actuators such as stepper motors and solenoid actuators (not shown), takes an opening degree according to a control signal from the ECU 200, and controls an EGR gas flow rate recirculated to the intake surge tank 104 through the EGR passage 152. . Since the EGR gas is a high-temperature exhaust gas discharged from the cylinder, when a large amount of EGR gas is recirculated to the intake air, the intake air temperature rises, and the intake volume efficiency of the engine decreases. In the present embodiment, in order to prevent this, a water-cooled or air-cooled EGR cooler 156 is provided in the EGR passage 152 upstream of the EGR valve 154. In the present embodiment, by using the EGR cooler 156 to reduce the temperature of the EGR gas recirculated to the intake system, it is possible to recirculate a relatively large amount of EGR gas while suppressing a decrease in the intake volume efficiency of the engine. ing.

  Furthermore, the ECU 200 according to the present embodiment is configured as a microcomputer having a known configuration, in which a CPU, a RAM, a ROM, an input port, and an output port are connected to each other via a bidirectional bus. The ECU 200 performs basic control such as fuel injection control and engine speed control of the engine 100, and also performs cooling control of the exhaust throttle valve 134 in this embodiment as will be described later.

  In order to perform these controls, a signal corresponding to the engine speed is input to the input port of the ECU 200 from a rotation speed sensor disposed in the vicinity of the crankshaft of the engine 100, and the engine intake air amount from the air flow meter 112 is input. Further, a signal corresponding to the accelerator pedal depression amount (accelerator opening) of the driver from an accelerator opening sensor arranged in the vicinity of an accelerator pedal (not shown) and an EGR valve opening arranged in the EGR valve 154 A signal representing the EGR valve opening degree, a cooling water temperature signal from a water temperature sensor (not shown), a signal representing a vehicle position altitude from an altitude sensor (not shown), and the like are input from the degree sensor.

  The output port of the ECU 200 is connected to the fuel injection valve 114 of the engine 100 via a fuel injection circuit (not shown), and controls the fuel injection amount from the fuel injection valve 114 and the fuel injection timing. Further, the output port of the ECU 200 is connected to the actuators of the EGR valve 154, the intake throttle valve 108, the exhaust throttle valve 134, and the water amount adjustment valve 142 via a drive circuit (not shown), and controls the respective valve openings.

  As described above, PM in the exhaust gas during engine operation is collected in the DPF 132, and the amount of PM collected by the DPF 132 gradually increases. In the present embodiment, the PM collection amount of the DPF 132 is estimated based on the integrated value of the intake air amount taken into the engine 100 from the previous regeneration, and when it reaches a predetermined value, the exhaust throttle valve 134 is reached. Is closed to reduce the intake air amount of the engine, and fuel is added to the exhaust system to raise the exhaust gas temperature so that the DPF 132 is regenerated. In addition to the estimation based on the integrated value of the intake air amount described above, the differential pressure sensor (not shown) measures the differential pressure across the DPF 132, and the increase in the amount of PM trapped due to the increase in the differential pressure. It may be detected.

  A processing procedure for cooling control of the exhaust throttle valve 134 of the present embodiment configured as described above will be described below with reference to the flowchart of FIG.

  Therefore, when control is started in ECU 200, it is determined in step S301 of this control routine whether or not regeneration of DPF 132 has started. Then, after waiting until the regeneration start is determined, when it is determined that the regeneration is started, the process proceeds to step S302, and the water amount adjustment valve 142 is fully opened.

  In the next step S303, whether or not the temperature of the cooling water exceeds a predetermined value (for example, 80 ° C.) based on a cooling water temperature signal from a water temperature sensor (not shown), in other words, whether or not it is within a predetermined value. Determined. When the temperature of the cooling water is within a predetermined value, this control routine is temporarily terminated. That is, the fully open state of the water amount adjustment valve 142 in step S302 is maintained as it is. Therefore, the cooling water of the engine 100 is circulated through the through hole 134 </ b> C formed in the valve shaft 134 </ b> B of the exhaust throttle valve 134 via the circulation path 140. Thus, since the valve shaft 134B is effectively cooled by the cooling water circulated through the through hole 134C, the valve shaft 134B is prevented from being distorted and the normal behavior of the exhaust throttle valve 134 is hindered. There is nothing.

  On the other hand, if it is determined in step S303 that the temperature of the cooling water exceeds the predetermined value, the process proceeds to step S304, the opening of the water amount adjusting valve 142 is controlled according to the cooling water temperature, and the water amount is adjusted. In this way, the circulation amount of the cooling water is limited, so that overheating of the engine 100 due to the excessive increase in the temperature of the cooling water can be avoided.

  Next, a control processing procedure at the time of engine start that is additionally executed in the above-described embodiment will be described with reference to a flowchart of FIG. When control is started in the ECU 200, it is determined in step S401 of this control routine whether the engine 100 is at a low temperature start or a high altitude start. If both are negative, the control routine is terminated.

  And in step S401, when either is affirmed, it progresses to step S402 and the water quantity adjustment valve 142 is fully opened. Thus, when the engine 100 is started at a low temperature or at a high altitude, the opening of the water amount adjustment valve 142 is fully opened, so that the amount of cooling water circulated through the through hole 134C formed in the valve shaft 134B is increased. Is heated by the exhaust gas passing through the exhaust passage 122, so that warm-up of the engine 100 is promoted. Thus, emission reduction and misfire during starting at low temperatures and starting at high altitudes are suppressed.

It is a schematic diagram which shows the outline of embodiment of the cooling control apparatus of the exhaust throttle valve which concerns on this invention. It is a fragmentary sectional view showing an embodiment of an exhaust throttle valve part in a cooling control device of an exhaust throttle valve concerning the present invention. It is a flowchart which shows an example of the control procedure in the cooling control apparatus of the exhaust throttle valve which concerns on this invention. It is a flowchart which shows an example of the additional control procedure in the cooling control apparatus of the exhaust throttle valve which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Engine main body 122 Exhaust passage 134 Butterfly type exhaust throttle valve 134B Valve shaft 134C Through-hole 136 Exhaust purification filter (DPF)
140 Circulating path 142 Water amount adjusting valve 200 Electronic control unit (ECU)

Claims (4)

In an exhaust gas purification apparatus for an internal combustion engine, comprising an exhaust gas purification filter installed in an exhaust passage of the internal combustion engine, and a butterfly type exhaust throttle valve disposed downstream of the exhaust gas purification filter,
A circulation path that communicates with a through hole formed in the valve shaft of the exhaust throttle valve and circulates cooling water of the internal combustion engine;
A water amount adjusting valve provided in the circulation path;
A butterfly-type exhaust throttle valve cooling control device comprising: control means for controlling an opening degree of the water amount adjustment valve so that a predetermined amount of cooling water flows through the through hole during regeneration of the exhaust purification filter.   2. The butterfly according to claim 1, wherein when the temperature of the cooling water exceeds a predetermined value, the control unit performs control so as to reduce the opening of the water amount adjustment valve in accordance with the temperature. Cooling control device for mold exhaust throttle valve.   2. The cooling control apparatus for a butterfly exhaust throttle valve according to claim 1, wherein the control means controls the opening of the water amount adjustment valve to be fully opened when the internal combustion engine is started at a low temperature.   2. The cooling control apparatus for a butterfly exhaust throttle valve according to claim 1, wherein the control unit controls the opening of the water amount adjustment valve to be fully opened when the internal combustion engine is started at a high altitude. 3.

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