초록 ▼

The present invention provides an engine exhaust gas purification device comprising a filter B provided in an exhaust passage (10) of an engine (1) for trapping particulate matter contained in the exhaust gas, a catalyst A for regenerating the filter B by burning the particulate matter trapped in th

The present invention provides an engine exhaust gas purification device comprising a filter B provided in an exhaust passage (10) of an engine (1) for trapping particulate matter contained in the exhaust gas, a catalyst A for regenerating the filter B by burning the particulate matter trapped in the filter B, an EGR valve (8) provided in an EGR passage (7) linking the intake side and exhaust side of the engine 1, an injector (2) for injecting fuel into a cylinder, and control unit (20) for controlling the injector (2) and EGR valve (8). During regeneration of the filter B, the control unit (20) close the EGR valve (8) when fuel injection from the injector (2) is controlled to supply unburned fuel components to the catalyst A, and open the EGR valve (8) when no fuel is injected from the injector (2) upon a request for speed reduction or the like. In so doing, residual unburned fuel components in the EGR passage (7) are scavenged by air.

대표청구항 ▼

What is claimed is: 1. An engine exhaust gas purification device comprising: a filter provided in an exhaust passage of an engine, for trapping particulate matter contained in exhaust gas; a catalyst provided on at least one of an upstream side of the filter and a surface of the filter, for regener

What is claimed is: 1. An engine exhaust gas purification device comprising: a filter provided in an exhaust passage of an engine, for trapping particulate matter contained in exhaust gas; a catalyst provided on at least one of an upstream side of the filter and a surface of the filter, for regenerating the filter; an EGR valve provided in an EGR passage linking an intake side and an exhaust side of the engine; an injector for injecting fuel into a cylinder of the engine; and control means for determining when the filter needs to be regenerated and for controlling the injector and the EGR valve; wherein, upon a determination that the filter needs to be regenerated, the control means forcibly regenerate the filter by controlling the injector to switch from performing normal injection when fuel injection is carried out to performing fuel injection that supplies unburned fuel components to the filter when fuel injection is carried out; and wherein the control means fully close the EGR valve during forcible regeneration while supplying unburned fuel components and open the EGR valve during forcible regeneration when fuel injection is not carried out, upon a request for speed reduction, so as to scavenge the EGR passage by air which is not mixed with fuel. 2. The engine exhaust gas purification device according to claim 1, wherein, during regeneration of the filter, the control means control an intake throttle valve provided in an intake passage of the engine to close. 3. The engine exhaust gas purification device according to claim 1, further comprising: a pipe linking the upstream side and a downstream side of the filter; and a differential pressure sensor provided at a point on the pipe, for detecting a differential pressure between the left and right of the pipe in relation to the position thereof on the pipe, wherein, when a detection value of the differential pressure sensor exceeds a predetermined differential pressure, the control means control fuel injection from the injector to regenerate the catalyst-carrying filter. 4. The engine exhaust gas purification device according to claim 1, wherein, during regeneration of the filter, the control means cause the injector to perform at least one form of injection from among a multi-injection, in which one or more sub-injections are performed following a main injection while a flame generated by the main injection continues to burn, and a post-injection, in which one or more sub-injections are performed following the main injection after the flame generated by the main injection has died out. 5. The engine exhaust gas purification device according to claim 4, wherein the control means first cause the injector to perform the multi-injection, and then cause the injector to perform the post-injection. 6. An engine exhaust gas purification device comprising: a catalyst-carrying filter provided in an exhaust passage of an engine, for trapping particulate matter contained in exhaust gas; an oxidation catalyst provided on an upstream side of the catalyst-carrying filter; an EGR valve provided in an EGR passage linking an intake side and an exhaust side of the engine; an injector for injecting fuel into a cylinder of the engine; and control means for determining when the filter need to be regenerated and for controlling the injector and the EGR valve; wherein, upon a determination that the catalyst-carrying filter needs to be regenerated, the control means forcibly regenerate the catalyst-carrying filter by controlling the injector to switch from performing normal injection when fuel injection is carried out to performing fuel injection that supplies unburned fuel components to the oxidation catalyst and the catalyst-carrying filter when fuel injection is carried out; and wherein the control means fully close the EGR valve during forcible regeneration while supplying unburned fuel components and open the EGR valve during forcible regeneration when fuel injection is not carried out, upon a request for speed reduction or the like, so as to scavenge the EGR passage by air which is not mixed with fuel. 7. The engine exhaust gas purification device according to claim 6, wherein, during regeneration of the catalyst-carrying filter, the control means control an intake throttle valve provided in an intake passage of the engine to close. 8. The engine exhaust gas purification device according to claim 6, further comprising: a pipe linking the upstream side of the oxidation catalyst and a downstream side of the catalyst-carrying filter; and a differential pressure sensor provided at a point on the pipe, for detecting a differential pressure between the left and right of the pipe in relation to the position thereof on the pipe, wherein, when a detection value of the differential pressure sensor exceeds a predetermined differential pressure, the control means control fuel injection from the injector to regenerate the catalyst-carrying filter. 9. The engine exhaust gas purification device according to claim 6, wherein an EGR cooler is provided in the EGR passage for cooling EGR gas, and the EGR valve is disposed on a downstream side of the flow of the EGR gas in relation to the EGR cooler. 10. The engine exhaust gas purification device according to claim 6, comprising a catalyst inlet exhaust gas temperature sensor for detecting the temperature of the exhaust gas at the inlet to the oxidation catalyst, wherein, when the temperature of the exhaust gas detected by the catalyst inlet exhaust gas temperature sensor is lower than a first predetermined temperature during regeneration of the catalyst-carrying filter, the control means cause the injector to perform a multi-injection, in which one or more sub-injections are performed following a main injection while a flame generated by the main injection continues to burn, and close the EGR valve. 11. The engine exhaust gas purification device according to claim 10, wherein, following the multi-injection, the control means cause the injector to perform a post-injection, in which one or more sub-injections are performed following the main injection after the flame generated by the main injection has died out. 12. The engine exhaust gas purification device according to claim 11, further comprising a filter inlet exhaust gas temperature sensor for detecting the temperature of the exhaust gas at the inlet to the catalyst-carrying filter, wherein, when the temperature of the exhaust gas detected by the filter inlet exhaust gas temperature sensor is equal to or greater than a second predetermined temperature which is higher than the first predetermined temperature, the control means cause the injector to perform the post-injection. 13. An engine exhaust gas purification device comprising: an intake throttle valve provided in an intake passage of an engine; a filter provided in an exhaust passage of the engine, for trapping particulate matter contained in exhaust gas; a catalyst provided on at least one of an upstream side of the filter and a surface of the filter, for regenerating the filter; an EGR valve provided in an EGR passage linking an intake side and an exhaust side of the engine; an injector for injecting fuel into a cylinder of the engine; and control means for determining when the filter need to be regenerated and for controlling the injector, the EGR valve, and the intake throttle valve; wherein, upon a determination that the filter needs to be regenerated, the control means forcibly regenerate the filter by controlling the injector to switch from performing normal injection when fuel injection is carried out to performing fuel injection that supplies unburned fuel components to the filter when fuel injection is carried out; and wherein the control means fully close the EGR valve during forcible regeneration while supplying unburned fuel components and control the intake throttle valve to close and the EGR valve to open during forcible regeneration when fuel injection is not carried out, upon a request for speed reduction, so as to scavenge the EGR passage by air which is not mixed with fuel. 14. An engine exhaust gas purification device comprising: an intake throttle valve provided in an intake passage of an engine; a catalyst-carrying filter provided in an exhaust passage of the engine, for trapping particulate matter contained in exhaust gas; an oxidation catalyst provided on an upstream side of the catalyst-carrying filter; an EGR valve provided in an EGR passage linking an intake side and an exhaust side of the engine; an injector for injecting fuel into a cylinder of the engine; and control means for determining when the filter need to be regenerated and for controlling the injector, the EGR valve, and the intake throttle valve; wherein, upon a determination that the catalyst-carrying filter needs to be regenerated, the control means forcibly regenerate the catalyst-carrying filter by controlling the injector to switch from performing normal injection when fuel injection is carried out to performing fuel injection that supplies unburned fuel components to the oxidation catalyst and the catalyst-carrying filter when fuel injection is carried out; and wherein the control means fully close the EGR valve during forcible regeneration while supplying unburned fuel components and control the intake throttle valve to close and the EGR valve to open during forcible regeneration when fuel injection is not carried out, upon a request for speed reduction, so as to scavenge the EGR passage by air which is not mixed with fuel.