Provided is a control device configured to be able to execute, in an engine which includes a DOC, a DPF, and a temperature increase unit including an exhaust throttle valve, for increasing a temperature of each of the DOC and the DPF, a forced regeneration process of removing PM deposited on the DPF by increasing the temperature of the DPF. The control device includes a flow rate estimation part configured to estimate an intake flow rate of a combustion gas sent into a cylinder of the engine. The flow rate estimation part is configured to estimate a first intake flow rate, which is the intake flow rate in the forced regeneration process, from an opening degree of the exhaust throttle valve and a first state amount which indicates an operation state of the engine including a rotation speed of the engine, based on a first relationship representing a relationship between the first intake flow rate, and the opening degree of the exhaust throttle valve and the first state amount, in the forced regeneration process.

A method is disclosed for cleaning a component of an exhaust aftertreatment system located downstream of a combustion engine in an exhaust flow path delimited by an outer wall. The exhaust aftertreatment system includes a first device releasably mounted in the outer wall upstream of the component and a second device releasably mounted in the outer wall downstream of the component, each of the devices being a sensor or an injector. The method includes sealing the exhaust flow path upstream of the first device and downstream of the second device, removing at least the first and second devices, thereby providing at least two openings in the outer wall, so that a cleaning flow path is provided, and introducing cleaning fluid into at least one of the openings, so that the cleaning fluid flows across the component via the cleaning flow path.

Provided is a diesel engine capable of regenerating a DPF even during no-load and/or light-load operation. In a DPF regeneration process, opening-degree reduction control S2 for an exhaust-air throttle valve is performed after a start condition S1 of the regeneration process of the DPF in which PM is deposited is satisfied. When exhaust air reaches a temperature equal to or higher than a predetermined after-injection permissible temperature TA, after-injection control is subsequently started S5. Post-injection control is started S7 after the exhaust air reaches a temperature equal to or higher than a predetermined post-injection permissible temperature TP by combustion of after-injection fuel. The PM deposited in the DPF is incinerated by the exhaust air increased in temperature by catalytic combustion of post-injection fuel in a valve downstream-side DOC.

A method is disclosed for cleaning a component of an exhaust aftertreatment system located downstream of a combustion engine in an exhaust flow path delimited by an outer wall. The exhaust aftertreatment system includes a first device releasably mounted in the outer wall upstream of the component and a second device releasably mounted in the outer wall downstream of the component, each of the devices being a sensor or an injector. The method includes sealing the exhaust flow path upstream of the first device and downstream of the second device, removing at least the first and second devices, thereby providing at least two openings in the outer wall, so that a cleaning flow path is provided, and introducing cleaning fluid into at least one of the openings, so that the cleaning fluid flows across the component via the cleaning flow path.

An exhaust gas purification control device includes an engine, an actuator using the engine as a driving source, an operation unit used by an operator to operate the actuator or the engine, an operation detector detecting whether or not the operation unit is being operated, a purification device for capturing soot in exhaust gas of the engine, an accumulation amount detector detecting an accumulation amount of the soot captured by the purification device, a regeneration unit for performing an regenerating operation of regenerating the purification device by burning the soot captured by the purification device, and a controller controlling the regenerating operation. The controller switches a control from a control of prioritizing an operation by the operation unit to a control of prioritizing the regenerating operation in a stepwise manner as the accumulation amount of the soot detected by the accumulation amount detector increases.

Provided is a diesel engine capable of regenerating a DPF even during no-load and/or light-load operation. In a DPF regeneration process, opening-degree reduction control S2 for an exhaust-air throttle valve is performed after a start condition S1 of the regeneration process of the DPF in which PM is deposited is satisfied. When exhaust air reaches a temperature equal to or higher than a predetermined after-injection permissible temperature TA, after-injection control is subsequently started S5. Post-injection control is started S7 after the exhaust air reaches a temperature equal to or higher than a predetermined post-injection permissible temperature TP by combustion of after-injection fuel. The PM deposited in the DPF is incinerated by the exhaust air increased in temperature by catalytic combustion of post-injection fuel in a valve downstream-side DOC.

An ECU 10 includes a valve control unit 101 for throttling a valve opening of at least one of an intake throttle valve or an exhaust throttle valve so that an upstream temperature of a DOC reaches a predetermined temperature; and a deposition condition determination unit 105 for determining whether a deposition condition that a SOF deposition amount on the DOC exceeds a predetermined deposition amount is satisfied. The valve control unit 101 includes a throttle amount decrease control execution unit 102 for executing throttle amount decrease control to decrease a throttle amount of the valve opening when the deposition condition is satisfied to be smaller than when the deposition condition is not satisfied.

Methods and systems are provided for an aftertreatment system. In one example, a method comprises regenerating a NO.sub.x trap during an engine shut-down event. The method further comprises reversing a direction of flow of a gas through a HP-EGR passage during the regenerating.

Provided is a control device configured to be able to execute, in an engine which includes a DOC, a DPF, and a temperature increase unit including an exhaust throttle valve, for increasing a temperature of each of the DOC and the DPF, a forced regeneration process of removing PM deposited on the DPF by increasing the temperature of the DPF. The control device includes a flow rate estimation part configured to estimate an intake flow rate of a combustion gas sent into a cylinder of the engine. The flow rate estimation part is configured to estimate a first intake flow rate, which is the intake flow rate in the forced regeneration process, from an opening degree of the exhaust throttle valve and a first state amount which indicates an operation state of the engine including a rotation speed of the engine, based on a first relationship representing a relationship between the first intake flow rate, and the opening degree of the exhaust throttle valve and the first state amount, in the forced regeneration process.

A control device is configured to direct an opening degree of a throttle valve disposed in an intake passage or an exhaust passage of an engine including a DOC disposed in the exhaust passage and a DPF disposed downstream of the DOC in the exhaust passage. The control device includes: a hysteresis occurring condition determination unit configured to determine whether a hysteresis occurring condition (predetermined time elapses after instructed opening degree of throttle valve becomes equal to or smaller than predetermined opening degree and/or predetermined time elapses after engine output becomes equal to or smaller than predetermined output) is met; and a hysteresis elimination execution unit configured to cause, if it is determined that the hysteresis occurring condition is met, the throttle valve to execute hysteresis elimination that involves temporarily increasing the opening degree of the throttle valve from the instructed opening degree and then returning it to the instructed opening degree.