Exhaust gas cleaning system for engineering vehicle

Abstract

An exhaust gas cleaning system is provided in an engineering vehicle such as a hydraulic excavator. During automatic regeneration, when a gate lock lever 5 is in a locked state and work is not performed, the exhaust gas temperature detected by the exhaust temperature detecting device 37 may be lower than the threshold value, so temperature-rising assistance is started as follows. The minimum engine output PS 1 (pump discharge pressure P 1 and pump discharge amount Q 1 ) is brought to engine output PS 2 (pump discharge pressure P 2 and pump discharge amount Q 2 ). In this way, a hydraulic load is applied to an engine to thereby increase exhaust gas temperature. When the work is resumed during the regeneration, an operator pulls down the gate lock lever to the first position A, and the engine output is returned to PS 1. Thus, the temperature-rising assistance is stopped, however the automatic regeneration is continued.

What is claimed is: 
     
         1 . A hydraulic excavator comprising:
 a diesel engine;   a hydraulic pump driven by the engine;   a plurality of actuators driven by a hydraulic fluid discharged from the hydraulic pump for driving a plurality of driven bodies;   a plurality of operating lever units for commanding the driven bodies to operate;   a plurality of flow control valves activated by said plurality of operating lever units for controlling flow of the hydraulic fluid supplied from the hydraulic pump to said plurality of actuators;   operation stopping means for disabling the operation of the driven bodies even if the operating lever units are operated; and   an exhaust gas cleaning system, wherein the exhaust gas cleaning system includes:   a filter device disposed in an exhaust system of the engine and including a filter for capturing particulate matter contained in exhaust gas;   a regeneration device having an oxidation catalyst and configured to supply unburned fuel to the oxidation catalyst to increase temperature of the exhaust gas thereby to burn and remove particulate matter deposited on the filter; and   a regeneration control device configured to control the start and stop of operation of the regeneration device,   wherein the operation stopping means includes a gate lock lever selectively operable between a first position to limit an entrance to a cab seat and a second position to open the entrance to the cab seat and configured such that, when the gate lock lever is located in the first position, the operation of said plurality of flow control valves by said plurality of operating lever units is enabled thereby to enable the operation of said plurality of actuators to drive said driven bodies and, when the gate lock lever is operated from the first position to the second position, the operation of said plurality of flow control valves by said plurality of operating lever units is disabled thereby to disable the operation of said plurality of actuators to drive the driven bodies,   wherein the exhaust gas cleaning system further includes temperature-rising assistance device for assisting temperature-rising of the regeneration device by increasing at least one of the discharge pressure and discharge amount of the hydraulic pump so as to apply a hydraulic load to the engine thereby to increase the temperature of the exhaust gas and oxidize the unburned fuel with the oxidation catalyst, and   wherein the regeneration control device is configured to start the operation of the temperature-rising assistance device when the gate lock lever is operated from the first position to the second position during the operation of the regeneration device.   
     
     
         2 . The hydraulic excavator according to  claim 1 ,
 wherein the regeneration control device is configured to stop the operation of the temperature-rising assistance means when the gate lock lever is operated from the second position to the first position to release disabling of the driving of said plurality of actuators and release the stop of the operation of the driven bodies.   
     
     
         3 . The hydraulic excavator according to  claim 1 ,
 wherein the temperature-rising assistance includes a control valve installed on a downstream side of a center bypass line connecting said plurality of control valves in series and having an open position and a closed position, and   wherein the regeneration control device is configured to apply the hydraulic load to the engine by switching the control valve from the open position to the closed position.