| 摘要 |
A control pressure switching valve is disposed between a displacement regulator and a pressure control valve. The control pressure switching valve is switched between a control position (j), in which a load sensing control pressure (PLS) is permitted to be outputted from the pressure control valve to the displacement regulator, and a control release position (k), in which the load sensing control pressure (PLS) to be outputted to the displacement regulator is reduced to a prescribed low pressure value. When the regeneration of a filter is determined to be necessary, the controller switches the control pressure switching valve to the control release position (k). When the load sensing control pressure (PLS) is reduced to the low pressure value with the control pressure switching valve switched to the control release position (k), the displacement regulator increases a delivery displacement of a hydraulic pump, thereby increasing rotational load of an engine. |
| 主权项 |
1. A construction machine, comprising:
an engine (10) being a prime mover, an exhaust gas purifying device (16) disposed at an exhaust side of said engine (10) and having a filter (19) for purifying an exhaust gas, a pressure detector (22, 23) disposed in said exhaust gas purifying device (16) to detect a differential pressure between the front and rear sides of said filter (19), a variable displacement type hydraulic pump (13) driven by said engine (10) and having a displacement variable portion (13A), a displacement regulator (26, 92) configured to variably control a delivery displacement of a pressurized oil by said hydraulic pump (13), a hydraulic actuator (33, 72) driven by said pressurized oil delivered from said hydraulic pump (13), a directional control valve (37, 75) configured to control a flow rate of said pressurized oil supplied from said hydraulic pump (13) to said hydraulic actuator (33, 72), a pressure control valve (44) configured to output a load sensing control pressure (PLS) to said displacement regulator (26, 92) such that a delivery pressure of said hydraulic pump (13) becomes higher than a maximum load pressure of said hydraulic actuator (33, 72) by a target differential pressure, and a controller (61) configured not only to control rotation of said engine (10) but also to perform a filter regeneration process in said exhaust gas purifying device (16), characterized in that: a control pressure switching valve (57) configured to be switched by a control signal from said controller (61) to either a control position (j), in which said load sensing control pressure (PLS) is permitted to be outputted without any change from said pressure control valve (44) to said displacement regulator (26, 92), or a control release position (k), in which said load sensing control pressure (PLS) to be outputted to said displacement regulator (26, 92) is reduced to a prescribed low pressure value, is disposed between said displacement regulator (26, 92) and said pressure control valve (44), when the regeneration of said filter (19) is determined to be necessary based on said differential pressure between the front and rear sides of said filter (19) detected by said pressure detector (22, 23), said controller (61) outputs said control signal, thereby switching said control pressure switching valve (57) from said control position (j) to said control release position (k), and when said load sensing control pressure (PLS) is reduced to said low pressure value with said control pressure switching valve (57) switched from said control position (j) to said control release position (k), said displacement regulator (26, 92) increases said delivery displacement of said hydraulic pump (13) so as to raise a temperature of said exhaust gas of said engine (10) to a temperature required for the regeneration of said filter (19), thereby increasing rotational load of said engine (10). |
