US 11,655,615 B1
Work machine and control method for work machine
Daiki Abe, Sakai (JP); Ryota Hamamoto, Sakai (JP); and Jun Tomita, Sakai (JP)
Assigned to KUBOTA CORPORATION, Osaka (JP)
Filed by Kubota Corporation, Osaka (JP)
Filed on Nov. 30, 2022, as Appl. No. 18/71,619.
Claims priority of application No. JP2022-018063 (JP), filed on Feb. 8, 2022.
Int. Cl. E02F 9/22 (2006.01); E02F 3/42 (2006.01); E02F 3/34 (2006.01)
CPC E02F 9/2285 (2013.01) [E02F 3/422 (2013.01); E02F 3/3414 (2013.01)] 20 Claims
OG exemplary drawing
 
1. The work machine comprising:
a bucket including a bucket proximal end and a bucket distal end opposite to the bucket proximal end;
an arm including an arm distal end that swingably supports the bucket proximal end and an arm proximal end opposite to the arm distal end;
a vehicle body swingably supporting the arm proximal end;
a bucket cylinder comprising:
a first chamber into which hydraulic fluid flows when the bucket distal end is tilted downward; and
a second chamber into which hydraulic fluid flows when the bucket distal end is tilted upward;
an arm cylinder comprising:
a third chamber into which hydraulic fluid flows when the arm distal end is raised; and
a fourth chamber into which hydraulic fluid flows when the arm distal end is lowered;
a first hydraulic pump configured to discharge hydraulic fluid to the bucket cylinder and the arm cylinder;
a first oil passage connecting the first hydraulic pump and the first chamber of the bucket cylinder;
a bucket control valve provided in the first oil passage and having a bucket control pilot port, the bucket control valve being configured to control hydraulic fluid supplied to the first chamber and the second chamber according to hydraulic pressure of the pilot oil applied to the bucket control pilot port;
a second oil passage connecting the bucket control valve and the second chamber;
a third oil passage connecting the first hydraulic pump and the third chamber of the arm cylinder;
an arm control valve provided in the third oil passage and having an arm control pilot port, the arm control valve being configured to control hydraulic fluid supplied to the third chamber and the fourth chamber according to hydraulic pressure of the pilot oil applied to the arm control pilot port;
a fourth oil passage connecting the arm control valve and the fourth chamber;
a second hydraulic pump configured to discharge pilot oil to control the arm control valve and the bucket control valve;
a first pilot oil passage connecting the arm control pilot port and the second hydraulic pump;
an arm pilot control valve provided in the first pilot oil passage and configured to control the hydraulic pressure of the pilot oil applied to the arm control pilot port based on an operation amount of an arm input member operated to raise and lower the arm;
an arm operation detection sensor configured to detect operation of the arm input member;
a second pilot oil passage connecting the bucket control pilot port and the second hydraulic pump;
a bucket pilot control valve provided in the second pilot oil passage and configured to control the hydraulic pressure of the pilot oil applied to the bucket control pilot port based on an operation amount of a bucket input member operated to swing the bucket;
a bucket operation detection sensor to detect operation of the bucket input member;
a bypass oil passage connecting the fourth oil passage to the first oil passage;
a switching mechanism configured to control connection of the fourth oil passage to the first oil passage via the bypass oil passage and disconnection of the fourth oil passage to the first oil passage via the bypass oil passage; and
circuitry configured to:
determine whether an uptilt operation to raise the arm and to tilt the bucket downward has been performed based on an output of the arm operation detection sensor and an output of the bucket operation detection sensor;
control the switching mechanism to connect the fourth oil passage to the first oil passage when it is determined that the uptilt operation has been performed.