초록 ▼

A control device for automatically controlling a pitch angle of a blade includes a hydraulic oil amount calculation unit and an open ratio setting unit. The hydraulic oil amount calculation unit is configured to calculate an amount of hydraulic oil passing through a blade tilt cylinder valve. The op

A control device for automatically controlling a pitch angle of a blade includes a hydraulic oil amount calculation unit and an open ratio setting unit. The hydraulic oil amount calculation unit is configured to calculate an amount of hydraulic oil passing through a blade tilt cylinder valve. The open ratio setting unit is configured to cause the blade tilt cylinder valve to open at a predetermined open ratio when a request for the pitch angle to be changed has been received, to cause the blade tilt cylinder valve to close when the calculated amount of hydraulic oil has reached a predetermined amount of hydraulic oil required for the change of the tilt angle, and to cause the open ratio to be smaller than the predetermined open ratio while a request for a predetermined action necessitating that hydraulic oil be supplied from a main valve is being received.

대표청구항 ▼

1. A control device for automatically controlling a pitch angle of a blade relative to the ground, the control device being provided to construction machine including the blade, a blade tilt cylinder and a blade tilt cylinder valve constituting a part of a main valve, the blade tilt cylinder valve b

1. A control device for automatically controlling a pitch angle of a blade relative to the ground, the control device being provided to construction machine including the blade, a blade tilt cylinder and a blade tilt cylinder valve constituting a part of a main valve, the blade tilt cylinder valve being linked to the blade tilt cylinder, the control device comprising: a hydraulic oil amount calculation unit configured to calculate an amount of hydraulic oil passing through the blade tilt cylinder valve based on an open ratio and a cumulative time of opening of the blade tilt cylinder valve; andan open ratio setting unit configured to cause the blade tilt cylinder valve to open at a predetermined open ratio when a request for the pitch angle to be changed from a first angle to a second angle has been received, the open ratio setting unit being configured to cause the blade tilt cylinder valve to close when the calculated amount of hydraulic oil has reached a predetermined amount of hydraulic oil required for the change from the first angle to the second angle,the open ratio setting unit being configured to cause the open ratio to be smaller than the predetermined open ratio while a request for a predetermined action necessitating that hydraulic oil be supplied from the main valve is being received. 2. The control device according to claim 1, wherein the predetermined action is lifting of the blade. 3. The control device according to claim 1, wherein the predetermined action is a course change. 4. The control device according to claim 1, wherein the predetermined action is tilting of the blade. 5. The control device according to claim 1, wherein the predetermined action is lifting of a ripper for excavation. 6. The control device according to claim 1, wherein the predetermined action is tilting of a ripper for excavation. 7. The control device according to claim 1, wherein the open ratio setting unit is configured to cause the blade tilt cylinder valve to be closed while the request for the predetermined action is being received. 8. The control device according to claim 1, wherein when the request for the change to the pitch angle has been received, the open ratio setting unit sets the open ratio in conformity with the received request. 9. The control device according to claim 1, wherein the open ratio setting unit is configured to cause a monitor to display that the open ratio is being made smaller than the predetermined open ratio while the open ratio is being made smaller than the predetermined open ratio. 10. The control device according to claim 1, further comprising: an engine rotational speed acquisition unit configured to acquire a rotational speed of an engine, anda maximum open ratio determination unit configured to determine a maximum open ratio of the blade tilt cylinder valve, in accordance with the rotational speed of the engine, whereinthe predetermined open ratio is the maximum open ratio. 11. The control device according to claim 1, further comprising a hydraulic oil amount monitoring unit configured to monitor whether or not the calculated amount of hydraulic oil has reached the predetermined amount of hydraulic oil required for the change from the first angle to the second angle, whereinthe hydraulic oil amount monitoring unit communicates to the open ratio setting unit that the calculated amount of hydraulic oil has reached the predetermined amount of hydraulic oil. 12. The control device according to claim 1, further comprising a work mode detection unit configured to detect a subsequent work mode of the blade, in accordance with a work mode of the blade when the request for the pitch angle to be changed from the first angle to the second angle has been received, whereinthe predetermined amount of hydraulic oil is set in accordance with the detected subsequent work mode. 13. A bulldozer comprising: a blade;a blade tilt cylinder configured to drive the blade;a main valve including a blade tilt cylinder valve linked to the blade tilt cylinder;a hydraulic pump configured to supply hydraulic oil to the main valve, the hydraulic pump driven by an engine; anda control device configured to automatically control a pitch angle of the blade relative to the ground, the control device having a hydraulic oil amount calculation unit and an open ratio setting unit,the hydraulic oil amount calculation unit being configured to calculate an amount of hydraulic oil passing through the blade tilt cylinder valve based on an open ratio and a cumulative time of opening of the blade tilt cylinder valve, andthe open ratio setting unit being configured to cause the blade tilt cylinder valve to open at a predetermined open ratio when a request for the pitch angle to be changed from a first angle to a second angle has been received, the open ratio setting unit being configured to cause the blade tilt cylinder valve to close when the calculated amount of hydraulic oil has reached a predetermined amount of hydraulic oil required for the change from the first angle to the second angle,the open ratio setting unit being configured to cause the open ratio to be smaller than the predetermined open ratio while a request for a predetermined action necessitating that hydraulic oil be supplied from the main valve is being received. 14. A pitch angle control method for automatically controlling a pitch angle of a blade relative to the ground in construction machine including the blade, a blade tilt cylinder, and a blade tilt cylinder valve constituting a part of a main valve, the blade tilt cylinder valve being linked to the blade tilt cylinder, the method comprising: opening the blade tilt cylinder valve at a predetermined open ratio when a request for the pitch angle to be changed from a first angle to a second angle has been received;setting the open ratio to be smaller than the predetermined open ratio while a request for a predetermined action necessitating that hydraulic oil be supplied from the main valve is being received;calculating an amount of hydraulic oil passing through the blade tilt cylinder valve based on an open ratio and a cumulative time of opening of the blade tilt cylinder valve; andclosing the blade tilt cylinder valve when the calculated amount of hydraulic oil has reached a predetermined amount of hydraulic oil required for the change from the first angle to the second angle.