Working Machine

The present invention relates to working machines such as skid-steer loaders and compact track loaders.

Working machines such as skid-steer loaders and compact track loaders include a machine body, traveling devices to support opposite side portions of the machine body such that the machine body is allowed to travel, and a working device connected to and supported by the machine body (see, for example, Japanese Unexamined Patent Application Publication No. 2012-207531). With regard to such a type of working machine, the working device includes arms connected to the machine body rotatably about a lateral axis extending perpendicularly to the up-and-down direction and extending forward from the machine body, and a work attachment connected to the distal ends of the arms. The work attachment is a function portion to perform a function depending on the content of work during the work, and examples thereof include various types that differ in work content (function) such as a bucket, a dozer blade, a hydraulic breaker, and a grapple.

The work attachment of such a type of working machine performs a function corresponding to the content of work while being in contact with a work target object. For example, a bucket and a dozer blade make contact with a work target object such as soil, mounds, or plants etc. and excavate or push and move them. A hydraulic breaker makes contact with and crushes a work target object such as bedrock or a building, etc. A grapple makes contact with and holds a work target object such as lumber (timber), etc.

Such a work attachment is brought into contact with a work target object by changing the posture of the work attachment and/or the arms. However, it may be difficult for a user to visually check whether the state of contact is appropriate, and excessive contact may occur.

Specifically, such a type of working machine includes hydraulic actuators to actuate the working device, the hydraulic actuators are actuated in response to an operation performed by the user, and the function of the work attachment is performed. In so doing, the user operates a manual operator (such as an operation lever) so that the work attachment comes into contact with a work target object. In some cases, however, the user cannot know the degree of contact (contact pressure) of the work attachment with the work target object and may bring the work attachment into excessive contact with (press the work attachment against) the work target object. Performing execution (working) in such an inappropriate manner may affect the appearance or efficiency of the work and, in some cases, may damage the work attachment and/or the working device.

Example embodiments of the present invention make it possible to provide working machines each capable of bringing a function portion into contact with a work target object such that the function portion can perform a function while preventing an excessive load on the function portion.

A working machine according to an aspect of an example embodiment of the present invention includes 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.

In an aspect of an example embodiment of the present invention, the controller may be 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.

In an aspect of an example embodiment of the present invention, changing the actuation state of the hydraulic actuator in action by the controller may include reducing an actuation speed of the hydraulic actuator from an actuation speed corresponding to an instruction provided by operation of the manual operator.

In an aspect of an example embodiment of the present invention, the working machine may further include a hydraulic pump to supply hydraulic fluid to the hydraulic actuator, and a prime mover to drive the hydraulic pump. Changing the actuation state of the hydraulic actuator in action by the controller may include 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.

In an aspect of an example embodiment of the present invention, the hydraulic actuator may include 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 may include 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. The controller may be 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.

In such a case the controller may be 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.

In such a case, the controller may be 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.

In such a case, the controller may be 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.

In an aspect of an example embodiment of the present invention, the working device may include 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 may include a first hydraulic cylinder to swing the arm and a second hydraulic cylinder to swing the bucket. The controller may be 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.

In such a case, the controller may be 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.

In an aspect of an example embodiment of the present invention, the function portion may include an attachable and detachable work attachment to be attached such that the work attachment is replaceable with another work attachment having a different function. The controller may be 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.

In such a case, the working machine may further include 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. The controller may be configured or programmed to recognize the work attachment selected by the user via the attachment selector as the work attachment which is attached.

The controller may be 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.

In an aspect of an example embodiment of the present invention, the working machine may further include 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. The controller may be 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.

In an aspect of an example embodiment of the present invention, the working device may include 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 may include a first hydraulic cylinder to swing the arm and a second hydraulic cylinder to swing the bucket. The controller may be 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.

In an aspect of an example embodiment of the present invention, the working machine may further include 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. The manual operator may include 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. The controller may be 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.

In such a case, the controller may be 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.

In such a case, the controller may be 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.

The working device may include 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 may include 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. The controller may be 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.

The working device may include an arm posture detector to detect a posture of the arm. The controller may be 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.

The arm posture detector may include an angle sensor to sense an angle of rotation of the arm about the first shaft. The controller may be 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.

The arm posture detector may include a stroke sensor to detect a degree of extension or retraction of the first hydraulic cylinder. The controller may be 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.

The working machine may further include at least one of a display or a speaker. The controller may be 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.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.

Example embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings. The drawings are to be viewed in an orientation in which the reference numerals are viewed correctly.

The following description discusses example embodiments of the present invention with reference to the drawings as necessary.

As illustrated in, a working machineincludes a machine body, a pair of traveling devicesto support left and right side portions of the machine bodysuch that the machine bodyis allowed to travel, and a working deviceconnected to the machine body. The working machinealso includes hydraulic actuators,, andto actuate the traveling devicesand the working device. That is, the working machineincludes a hydraulic circuit(hydraulic system) including the hydraulic actuators,, andto actuate the traveling devicesand the working deviceand hydraulic pump(s) to supply hydraulic fluid to the hydraulic actuators,, and. Accordingly, the working machineincludes a prime moverto drive the hydraulic pump. The working machinefurther includes manual operatorsandoperated by a user in relation to the actuation of the hydraulic actuators,, andand a controllerto control the actuation of the hydraulic actuators,, and. In the present example embodiment, the working machineincludes a displayto display information relating to work.

The machine bodyincludes a frame chassis, a seatprovided on the frame chassis, and a seat-protecting mechanismto protect the seat.

The frame chassisis made of sheet metal, has a three-dimensional shape suitable for the shape and size of the working machine, and defines a prime mover chamber ER that contains the prime moverat a rear portion in a front-rear direction.

The seatis located forward of the prime mover chamber ER (prime mover) and is fixed to the frame chassis. In the present example embodiment, the seat-protecting mechanismis a so-called cabin that surrounds the seat. The seatis located forward of the prime mover chamber ER as described above, and therefore the cabinis also located forward of the prime mover chamber ER. That is, the cabindefines an operation room RM in which the user who sits on the seatstays at a position forward of the prime mover chamber ER.

The cabinhas front, back, left, and right windows, and the manual operatorsandoperated by the user are provided in the cabin(in the operation room RM). The manual operatorsandincluded in the working machineaccording to the present example embodiment include a manual operator (hereinafter referred to as a first manual operator)to control the traveling devicesand a manual operator (hereinafter referred to as a second manual operator)to control the working device. The first manual operatorand the second manual operatorare provided in the operation room RM such that they can be operated by the user who sits on the seat. In the present example embodiment, the first manual operatorand the second manual operatorare provided at a front portion in the seat.

The first manual operatorand the second manual operatorare respective mechanical lever devices. That is, the first manual operatorand the second manual operatorinclude operation leversandpivotable along the front-rear direction and left-right direction. The traveling devicesand the working deviceare actuated based on the degree and direction of pivot of the operation leversand. In the following description, the operation leverof the first manual operatoris referred to as a first operation lever, and the operation leverof the second manual operatoris referred to as a second operation lever.

More specifically, the first manual operatorchanges the direction of travel of the traveling deviceswhen the direction of pivot of the first operation leveris changed, and controls the travel speed of the traveling devicesbased on the degree of pivot of the first operation lever. The second manual operatorchanges upward/downward movement of arm(s)of the working device(described later) or upward/downward swinging (rotational) movement of a work attachmentor the like which is a function portion of the working device(described later) when the direction of pivot of the second operation leveris changed, and controls the speed of the upward/downward movement of the arm(s)or the speed of the upward/downward pivot of the work attachmentor the like based on the degree of pivot of the second operation lever. Note that, with regard to the working machineaccording to the present example embodiment, in the case where the work attachment includes a hydraulic actuator (such as a hydraulic cylinder) to perform its own function (its independent function), another manual operator (AUX switchin the present example embodiment) that differs from the second operation levermay be operated in relation to the function (actuation of the hydraulic actuator) of the work attachment

The pair of traveling devicessupport the opposite side portions of the frame chassis. In the present example embodiment, the pair of traveling devicesare crawler traveling devices. Specifically, each of the pair of traveling devicesincludes idler(s), driving wheel(s), a plurality of rollers, an endless crawler belt, and traveling motor(s).illustrates a left side surface of the working machine, and therefore only one of the traveling devicesthat supports the left side portion of the frame chassisis illustrated.

A pair of the idlersare provided at an interval in the front-rear direction. The plurality of rollersare provided between the pair of idlers. The driving wheel(s)is/are located higher than the rollers. The crawler beltis wound around the idlers, the driving wheel(s), and the rollers.

The traveling motorsdrive the driving wheelsto rotate. In the present example embodiment, each traveling motoris a hydraulic motor. Accordingly, the traveling motoras a hydraulic actuatorfor travel is connected in the hydraulic circuit. The left and right pair of traveling devicesrotate and drive the driving wheelsto cause the crawler beltsto turn.

The working deviceincludes the arm(s)connected to the machine bodyand a work attachmentas a function portion directly or indirectly connected to the arm(s).

More specifically, the working deviceincludes the arm(s)which is/are connected to the machine bodyrotatably about a first shaft Sextending perpendicularly to the up-and-down direction and which extend(s) to a position forward of the machine body, the work attachmentas a function portion to perform a function corresponding to specific work, and coupler(s)to which the work attachmentis detachably attached, and the coupler(s)is connected to the distal portion(s) of the arm(s)rotatably about a second shaft Sextending perpendicularly to the up-and-down direction.

In the present example embodiment, the working machinefurther includes a plurality of hydraulic actuatorsandto actuate the working device. The plurality of hydraulic actuatorsandinclude hydraulic actuatorsandto switch between a state in which the work attachment (function portion)or the like is in contact with a work target object and a state in which the work attachment (function portion)or the like is not in contact with the work target object. In the present example embodiment, the hydraulic actuatorsandto actuate the working deviceare fluidly connected in the hydraulic circuitand are also mechanically connected in the working device.

The arm(s)extends in one direction. Each armincludes a proximal portion directly or indirectly connected to the machine bodyrotatably about the first shaft Sand a distal portion at the opposite end of the armfrom the proximal portion. The proximal portion and the distal portion are arranged in the one direction. In the present example embodiment, the distal portion of the armbends downward. The proximal portion of the armis indirectly connected to the machine body. Specifically, the working machineincludes link(s)connected to a rear portion of the frame chassisand extending in the up-and-down direction. Each linkincludes a lower end portion and an upper end portion. The lower end portion of the linkis connected to the frame chassisvia a lateral shaft Sextending perpendicularly to the up-and-down direction. On the other hand, a corresponding armis rotatably connected to the upper end portion of the linkvia the first shaft S. Accordingly, the working machineincludes an arm posture detector SEto detect the posture of the arm(s). The arm posture detector SEmay be a detector to directly detect the posture of the arm(s), and may be a detector to detect something whose parameter changes in relation to (in proportion to) changes in posture (tilt angle) of the arm(s). Specifically, examples of the arm posture detector SEinclude a stroke sensor to detect the degree of extension or retraction of the first hydraulic cylinder(s)to rotate (swing) the arm(s), and a first angle sensor SEto sense the angle of rotation of the arm(s)about the first shaft S. In the present example embodiment, the arm posture detector SEis an angle sensor SEelectrically connected to the controllerto sense the angle of rotation of the arm(s)about the first shaft S(such an angle sensor is hereinafter referred to as a “first angle sensor”).

In the present example embodiment, such armsconfigured as described above are provided on left and right sides of the cabin. That is, the working deviceincludes a pair of armsarranged with the cabintherebetween. The shapes and arrangement of the pair of armsare each symmetrical with respect to the widthwise (lateral) center of the cabin. Accordingly, a left and right pair of the linksare connected to the arms.illustrates the left side surface of the working machine, and therefore only the armand the linkprovided on the left side are illustrated similarly to the traveling devices.

The working deviceincludes, as the hydraulic actuatorsandto actuate the working device, first hydraulic cylinder(s)to rotate the arm(s)about the first shaft Sto raise/lower the distal portion of the arm(s), and second hydraulic cylinder(s)to rotate the coupler(s)(work attachment) about the second shaft S. Accordingly, the working machineincludes an angle sensor SEelectrically connected to the controllerto sense the angle of rotation of the coupler(s)(work attachmentor the like) about the second shaft S(such an angle sensor is hereinafter referred to as a “second angle sensor”).

The first hydraulic cylinder(s)and the second hydraulic cylinder(s)can each be used to bring the work attachmentor the like into contact with a work target object T. In the working machineaccording to the present example embodiment, the first hydraulic cylinder(s)is/are used as hydraulic actuator(s) to automatically adjust the degree of contact when the work attachmentis brought into contact with the work target object T.

The first hydraulic cylinder(s)and the second hydraulic cylinder(s)include hydraulic cylinders which include hydraulic actuators, and are therefore connected in the hydraulic circuit. The first hydraulic cylinder(s)and the second hydraulic cylinder(s)each include 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. Each hydraulic cylinder includes a first port Pa, Pbto 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 Pa, Pbto 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,. That is, the first hydraulic cylinder(s)and the second hydraulic cylinder(s)are double-acting hydraulic cylinders.