Working machine

Abstract

A working machine includes a machine body, a working device including a function portion to perform a function while in contact with a work target object, a hydraulic actuator to switch between a state in which the function portion contacts the work target object and a state in which the function portion is not in contact with the work target object, a manual operator to be operated in relation to actuation of the hydraulic actuator, and a controller configured or programmed to control the actuation of the hydraulic actuator. The controller is configured or programmed to derive a degree of contact of the function portion with the work target object based on a pressure of hydraulic fluid supplied to the hydraulic actuator, and if the derived degree matches or substantially matches a preset optimal degree, change an actuation state of the hydraulic actuator in action.

What is claimed is: 
     
         1 . A working machine comprising:
 a machine body;   a working device connected to the machine body and including a function portion to perform a function corresponding to a content of work while in contact with a work target object;   a hydraulic actuator to switch between a first state in which the function portion is in contact with the work target object and a second state in which the function portion is not in contact with the work target object;   a manual operator to be operated by a user in relation to actuation of the hydraulic actuator; and   a controller configured or programmed to control the actuation of the hydraulic actuator;   
       wherein
 the controller is configured or programmed to:
 derive a degree of contact of the function portion with the work target object based on a pressure of hydraulic fluid supplied to the hydraulic actuator; and 
 if the derived degree of contact matches or substantially matches a preset optimal degree of contact, change an actuation state of the hydraulic actuator in action. 
 
 
     
     
         2 . The working machine according to  claim 1 , wherein the controller is configured or programmed to change the actuation state of the hydraulic actuator in action while the manual operator is operated in relation to the actuation of the hydraulic actuator. 
     
     
         3 . The working machine according to  claim 1 , wherein changing the actuation state of the hydraulic actuator in action by the controller includes reducing an actuation speed of the hydraulic actuator from an actuation speed corresponding to an instruction provided by operation of the manual operator. 
     
     
         4 . The working machine according to  claim 1 , further comprising:
 a hydraulic pump to supply hydraulic fluid to the hydraulic actuator; and   a prime mover to drive the hydraulic pump; wherein   changing the actuation state of the hydraulic actuator in action by the controller includes reducing an actuation speed of the hydraulic actuator in action from an actuation speed corresponding to a combination of a drive rotational speed of the prime mover and an instruction provided by operation of the manual operator.   
     
     
         5 . The working machine according to  claim 2 , wherein
 the hydraulic actuator includes a hydraulic cylinder including a tubular cylinder and a piston rod inserted in the tubular cylinder such that the piston rod is extendable out of and retractable into the tubular cylinder, the hydraulic cylinder being operable to switch between the first state and the second state by extending or retracting via extension of the piston rod out of the tubular cylinder or retraction of the piston rod into the tubular cylinder;   the hydraulic cylinder includes a first port to allow hydraulic fluid to be supplied to the tubular cylinder to move the piston rod in a direction in which the piston rod extends out of the tubular cylinder and a second port to allow hydraulic fluid to be supplied to the tubular cylinder to move the piston rod in a direction in which the piston rod retracts into the tubular cylinder; and   the controller is configured or programmed to, while the manual operator is operated in relation to extension or retraction of the hydraulic cylinder that is the actuation of the hydraulic actuator:
 derive the degree of contact of the function portion with the work target object based on the pressure of hydraulic fluid at least at the first port or the second port of the hydraulic cylinder; and 
 if the derived degree of contact matches or substantially matches the preset optimal degree of contact, change a movement state of the piston rod of the hydraulic cylinder that is the actuation state of the hydraulic actuator in action. 
   
     
     
         6 . The working machine according to  claim 5 , wherein the controller is configured or programmed to, while the manual operator is operated in relation to the extension or retraction of the hydraulic cylinder, reduce a movement speed of the piston rod of the hydraulic cylinder in action as the derived degree of contact approaches the preset optimal degree of contact. 
     
     
         7 . The working machine according to  claim 6 , wherein the controller is configured or programmed to, while the manual operator is operated in relation to the extension or retraction of the hydraulic cylinder, cause the piston rod to stop moving when the derived degree of contact changes from a degree other than the preset optimal degree of contact to a degree matching or substantially matching the preset optimal degree of contact. 
     
     
         8 . The working machine according to  claim 7 , wherein the controller is configured or programmed to, after changing the actuation state of the hydraulic cylinder while the manual operator is operated in relation to the extension or retraction of the hydraulic cylinder, when the operation of the manual operator in relation to the extension or retraction of the hydraulic cylinder is stopped and then the operation is resumed, cause the piston rod to move in accordance with an instruction provided by the resumed operation of the manual operator. 
     
     
         9 . The working machine according to  claim 5 , wherein
 the working device includes:
 an arm extending from the machine body and connected to the machine body such that the arm is swingable up and down; and 
 a bucket which is the function portion swingably connected to a distal portion of the arm; 
   the hydraulic cylinder includes a first hydraulic cylinder to swing the arm and a second hydraulic cylinder to swing the bucket; and   the controller is configured or programmed to, while the manual operator is operated to move the piston rod of the first hydraulic cylinder to lower the arm or to move the piston rod of the second hydraulic cylinder to bring the bucket into a discharging posture after the derived degree of contact reaches a value equal to or less than a specified value corresponding to a state in which the bucket is not in contact with a ground which is the work target object:
 derive the degree of contact of the bucket with the ground which is the work target object based on the pressure of hydraulic fluid at least at the first port or the second port of the first hydraulic cylinder or the second hydraulic cylinder in which the piston rod is moved by operating the manual operator; and 
 if the derived degree of contact matches or substantially matches the preset optimal degree of contact, reduce a movement speed of the piston rod. 
   
     
     
         10 . The working machine according to  claim 9 , wherein the controller is configured or programmed to derive the degree of contact of the bucket with the ground which is the work target object based on a relationship between the pressure of hydraulic fluid at the first port and the pressure of hydraulic fluid at the second port. 
     
     
         11 . The working machine according to  claim 5 , wherein
 the function portion includes an attachable and detachable work attachment to be attached such that the work attachment is replaceable with another work attachment having a different function; and   the controller is configured or programmed to recognize the work attachment which is attached, and, if the recognized work attachment is a specific function portion, change the movement state of the piston rod of the hydraulic cylinder in action when the derived degree of contact matches or substantially matches the preset optimal degree of contact.   
     
     
         12 . The working machine according to  claim 11 , further comprising:
 an attachment selector to be used by the user to select a work attachment to be used from a plurality of types of work attachments having different functions; wherein   the controller is configured or programmed to recognize the work attachment selected by the user via the attachment selector as the work attachment which is attached.   
     
     
         13 . The working machine according to  claim 11 , wherein the controller is configured or programmed to compare the derived degree of contact with one of a plurality of the preset optimal degrees of contact corresponding to the respective functions of the plurality of types of work attachments that corresponds to the recognized work attachment. 
     
     
         14 . The working machine according to  claim 5 , further comprising:
 one or more supply-discharge passages connected to the first port and/or the second port of the hydraulic cylinder; and   one or more sensors to detect a pressure of hydraulic fluid in the one or more supply-discharge passages; wherein   the controller is configured or programmed to, if a detection result from the one or more sensors exceeds a predetermined pressure while the manual operator is operated in relation to the extension and retraction of the hydraulic cylinder, change the movement state of the piston rod of the hydraulic cylinder in action to a state differing from an instruction provided by the operation of the manual operator.   
     
     
         15 . The working machine according to  claim 5 , wherein
 the working device includes:
 an arm extending from the machine body and connected to the machine body such that the arm is swingable up and down; and 
 a bucket which is the function portion swingably connected to a distal portion of the arm; 
   the hydraulic cylinder includes a first hydraulic cylinder to swing the arm and a second hydraulic cylinder to swing the bucket; and   the controller is configured or programmed to, if the pressure of hydraulic fluid at the first port or the second port of the first hydraulic cylinder exceeds a threshold for a certain period of time while the manual operator is operated on the first hydraulic cylinder to lower the arm, cause the piston rod of the first hydraulic cylinder to stop moving.   
     
     
         16 . The working machine according to  claim 5 , further comprising:
 one or more supply-discharge passages connected to the first port and/or the second port of the hydraulic cylinder;   a control valve to adjust a flow rate of hydraulic fluid flowing through the one or more supply-discharge passages; and   one or more sensors to detect the pressure of hydraulic fluid in the one or more supply-discharge passages; wherein   the manual operator includes an operator to receive input relating to actuation of the working device and to control a flow rate of the control valve based on the received input; and   the controller is configured or programmed to, if the controller recognizes the attached function portion as a specific function portion and a detection result from the one or more sensors exceeds a threshold for a certain period of time while the input is received by the operator, control the control valve such that the flow rate of hydraulic fluid achieved by the control valve is zero or is lower than a flow rate of hydraulic fluid corresponding to the input received by the operator.   
     
     
         17 . The working machine according to  claim 16 , wherein the controller is configured or programmed to, from when the input received by the operator starts being kept constant or substantially constant to when a change in the input received by the operator is detected, control the control valve such that the flow rate of hydraulic fluid achieved by the control valve is lower than the flow rate of hydraulic fluid corresponding to the input received by the operator that is kept constant or substantially constant. 
     
     
         18 . The working machine according to  claim 16 , wherein the controller is configured or programmed to, in a case that the input is received by the operator for a certain period of time or more also after the detection result from the one or more sensors exceeds the threshold while the input is received by the operator and then the input received by the operator is kept constant or substantially constant, repeat the following until next time input received by the operator is detected:
 actuating the control valve when the detection result from the one or more sensors is less than the threshold; and   stopping actuation of the control valve when the detection result from the one or more sensors exceeds the threshold.   
     
     
         19 . The working machine according to  claim 5 , wherein
 the working device includes:
 an arm extending from the machine body and connected to the machine body such that the arm is swingable about a first shaft perpendicular to an up-and-down direction; and 
 an earth auger connected to a distal portion of the arm such that the earth auger is swingable about a second shaft perpendicular to the up-and-down direction, the earth auger being the function portion and including a digging drill and a hydraulic motor to rotate the digging drill, the digging drill including a shaft body including a pointed end and a helical blade attached around the shaft body; 
   the hydraulic cylinder includes a first hydraulic cylinder to swing the arm about the first shaft and a second hydraulic cylinder to swing the earth auger about the second shaft; and   the controller is configured or programmed to, while the hydraulic motor is stopped;
 derive a degree of contact of the earth auger with soil which is the work target object based on a pressure of hydraulic fluid supplied to at least one of the hydraulic cylinder or the second hydraulic cylinder; and 
 change the movement state of the piston rod of the hydraulic cylinder and set a digging depth of the earth auger in the soil to zero if the derived degree of contact matches or substantially matches the preset optimal degree of contact, wherein changing the movement state of the piston rod of the hydraulic cylinder includes stopping movement of the piston rod of the first hydraulic cylinder and the piston rod of the second hydraulic cylinder. 
   
     
     
         20 . The working machine according to  claim 19 , wherein
 the working device includes an arm posture detector to detect a posture of the arm; and   the controller is configured or programmed to, under a condition in which the set digging depth is zero, recognize a current digging depth of the earth auger in the soil based on a detection result from the arm posture detector.   
     
     
         21 . The working machine according to  claim 20 , wherein
 the arm posture detector includes an angle sensor to sense an angle of rotation of the arm about the first shaft; and   the controller is configured or programmed to, under the condition in which the set digging depth is zero, recognize the current digging depth of the earth auger in the soil based on a detection result from the angle sensor.   
     
     
         22 . The working machine according to  claim 20 , wherein
 the arm posture detector includes a stroke sensor to detect a degree of extension or retraction of the first hydraulic cylinder; and   the controller is configured or programmed to, under the condition in which the set digging depth is zero, recognize the current digging depth of the earth auger in the soil based on a detection result from the stroke sensor.   
     
     
         23 . The working machine according to  claim 20 , further comprising at least one of a display or a speaker; wherein
 the controller is configured or programmed to, after determining that the current digging depth of the earth auger in the soil is a preset digging depth, cause at least one of the display or the speaker to provide a notification indicating that the current digging depth of the earth auger in the soil is the preset digging depth.