Patent Description:
A work machine equipped with an elevating cab configured to rise and lower has been known (see, for example, <CIT>).

Moreover, <CIT> discloses a work machine which has a function to prevent the interference of a lift-mag and a cab. <CIT> provides the basis for the two-part form of claim <NUM>.

<CIT> discloses a cabin that is moved widthwise outside a working machine to avoid interference with a boom.

<CIT> discloses imposing a motion restriction on a construction machine based on detection of a person around the construction machine.

According to the above-described conventional work machine, shaking during traveling may affect the fatigue life of a structure that moves up and down the elevating cab (operator cabin), etc. According to the above-described conventional work machine, however, no consideration is given to shaking during traveling.

Therefore, in view of the above-described circumstances, an object is to reduce the effect of shaking during traveling.

A work machine according to an embodiment of the present invention includes an elevating cab, a detection part configured to detect the position of the elevating cab, and a control part configured to fix the travel speed of the work machine to low speed when a traveling operation is performed while the position of the elevating cab detected by the detection part is higher than a predetermined height.

The effect of shaking during traveling is reduced.

An embodiment of the invention is described below with reference to the drawings. <FIG> is an overall schematic diagram of a work machine according to this embodiment.

A work machine <NUM> includes a lower traveling structure <NUM>, a swing mechanism <NUM>, an upper swing structure <NUM>, a boom <NUM>, an arm <NUM>, an end attachment <NUM>, a boom cylinder <NUM>, an arm cylinder <NUM>, an end attachment cylinder <NUM>, a cab (operator cabin) <NUM>, an operating device <NUM>, a controller (control device) <NUM>, and a display <NUM>. The operating device <NUM>, the controller (control device) <NUM>, and the display <NUM> are provided in the cab <NUM>.

The upper swing structure <NUM> is swingably mounted on the lower traveling structure <NUM> of the work machine <NUM> via the swing mechanism <NUM>. Furthermore, the boom <NUM> is pivotably connected to the front center of the upper swing structure <NUM>. The arm <NUM> is pivotably connected to the distal end of the boom <NUM>. The end attachment <NUM> is pivotably connected to the distal end of the arm <NUM>. While the end attachment <NUM> is a lifting magnet according to this embodiment, another end attachment such as a grapple or a demolition fork may also be attached depending on the type of work.

Furthermore, the cab <NUM> is provided on the upper swing structure <NUM> in such a manner as to be vertically movable via a cab riser <NUM>. Hereinafter, such a cab that can rise and lower may be referred to as "elevating cab. " <FIG> illustrates the cab <NUM> moved up to its highest position by the cab riser <NUM>. Furthermore, the cab <NUM> is positioned beside (normally, on the left side of) the boom <NUM>.

Furthermore, a camera <NUM> or the like is attached to the upper swing structure <NUM>. The camera <NUM> is an image capturing device that captures an image of an area surrounding the work machine <NUM>. According to this embodiment, the camera <NUM> is one or more cameras attached to the upper swing structure <NUM>.

The operating device <NUM> is a device that an operator uses to operate hydraulic actuators. The operating device <NUM> supplies hydraulic oil discharged by a pilot pump to the pilot ports of the respective corresponding flow control valves of hydraulic actuators through pilot lines. The method of controlling hydraulic actuators, however, may be configured as desired to the extent that hydraulic actuators are driven according to the amount of operation of the operating device <NUM>, and is configured using an appropriate method. For example, the amount of driving of hydraulic actuators may be calculated by the controller <NUM>, which converts the amount of operation of the operating device <NUM> to other information such as voltage.

The controller <NUM> is a control device for controlling the work machine <NUM> and is constituted of a computer including a CPU, a RAM, a ROM, and a non-volatile memory, for example. Furthermore, the controller <NUM> reads programs corresponding to various functional elements from the ROM, loads them into the RAM, and causes the CPU to execute processes corresponding to the various functional elements.

Next, the cab riser <NUM> is described in detail with reference to <FIG> is a diagram illustrating the cab riser of the work machine according to this embodiment.

As illustrated in <FIG>, the cab riser <NUM> includes a parallel link mechanism <NUM> that keeps the cab <NUM> in a predetermined position (a horizontal state) and a cab raising cylinder <NUM> that drives the parallel link mechanism <NUM> to drive the cab <NUM> to rise and lower.

The parallel link mechanism <NUM> includes a support tower structure <NUM> that stands on the upper swing structure <NUM>, an L-shaped platform <NUM> supporting the cab <NUM> from the lower side, and an upper link <NUM> and a lower link <NUM> pivotably connected between the support tower structure <NUM> and the platform <NUM>. Specifically, the platform <NUM> is provided on the lower side of the cab <NUM> as a one-piece structure with the cab <NUM>.

Furthermore, the upper link <NUM> has its upper end connected to the platform <NUM> via an upper end pin <NUM> and has its lower end connected to the support tower structure <NUM> via a lower end pin <NUM>. The lower link <NUM> has its upper end connected to the platform <NUM> via an upper end pin <NUM> and has its lower end connected to the support tower structure <NUM> via a lower end pin <NUM>. Although not depicted in <FIG>, which is a side view, the upper link <NUM> and the lower link <NUM> are constituted of respective pairs of left and right links.

The cab raising cylinder <NUM> controls the pivoting of the upper link <NUM> and the lower link <NUM>. Specifically, the proximal end of the cab raising cylinder <NUM> is pivotably supported at a lower portion of the support tower structure <NUM> via a cylinder pin <NUM>. Furthermore, the distal end of a rod 62a of the cab raising cylinder <NUM> is connected to a connection member (not depicted) between the left and right upper links <NUM> via a rod pin <NUM>.

According to this configuration, hydraulic oil is supplied from a hydraulic pump to the cab raising cylinder <NUM> to drive the cab riser <NUM> to rise and lower. Specifically, the cab riser <NUM> can move the cab <NUM> up and down while causing the upper link <NUM> and the lower link <NUM> to draw circular arcs with the lower end pins <NUM> and <NUM> serving as pivot points by extending and retracting the cab raising cylinder <NUM>. The cab <NUM> can also move forward and backward in addition to moving upward and downward.

The cab riser <NUM> includes an angle sensor <NUM>. Specifically, the angle sensor <NUM> is provided at one end of the pivot shaft of the lower end pin <NUM> to detect the pivot angle of the upper link <NUM> from its initial position. The initial position is a position when the cab <NUM> is at its lowest position. The angle sensor <NUM> is provided to prevent the cab <NUM> and the end attachment <NUM> from interfering with each other.

Specifically, the position of the cab <NUM> is calculated based on an angle detected by the angle sensor <NUM>, and interference avoidance control is performed when it is determined that the relative distance between the cab <NUM> and the end attachment <NUM> in the front-to-back direction is less than a predetermined distance. According to the interference avoidance control, for example, the boom <NUM>, the arm <NUM>, etc., are controlled to move slowly irrespective of the operator's operation.

The angle sensor <NUM> may be any angle sensor, and for example, a rotary potentiometer or the like is used. Furthermore, the angle sensor <NUM> may also be provided at one end of the pivot shaft of the lower end pin <NUM> of the lower link <NUM> to detect the pivot angle of the lower link <NUM> from its initial position.

Next, a basic system of the work machine <NUM> according to this embodiment is described with reference to <FIG> is a diagram illustrating an example configuration of the basic system of the work machine according to this embodiment.

In <FIG>, a mechanical power transmission line, a hydraulic oil line, a pilot line, and an electric control line are indicated by a double line, a solid line, a dashed line, and a one-dot chain line, respectively. The same applies to <FIG> and <FIG>.

The basic system of the work machine <NUM> mainly includes an engine <NUM>, a pump regulator <NUM>, a main pump <NUM>, a control pump <NUM>, a control valve <NUM>, the operating device <NUM>, a solenoid valve <NUM>, a discharge pressure sensor <NUM>, an operating pressure sensor <NUM>, the controller <NUM>, a switch <NUM>, a switch <NUM>, and motor regulators <NUM>.

The engine <NUM> is the drive source of the work machine <NUM>. According to this embodiment, the engine <NUM> is, for example, a diesel engine serving as an internal combustion engine that operates to maintain a predetermined rotational speed. The output shaft of the engine <NUM> is connected to the input shafts of the main pump <NUM> and the control pump <NUM>.

The main pump <NUM> is a device for supplying hydraulic oil to the control valve <NUM> via a hydraulic oil line, and is, for example, a swash plate variable displacement hydraulic pump.

The pump regulator <NUM> is a device for controlling the discharge quantity of the main pump <NUM>. According to this embodiment, the pump regulator <NUM> controls the discharge quantity of the main pump <NUM> by, for example, adjusting the swash plate tilt angle of the main pump <NUM> according to the discharge pressure of the main pump <NUM>, a command current from the controller <NUM>, etc..

The control pump <NUM> is a device that supplies hydraulic oil to various kinds of hydraulic control devices including the operating device <NUM>, and is, for example, a fixed displacement hydraulic pump.

The control valve <NUM> is a hydraulic control device that controls a hydraulic system in the work machine <NUM>.

Specifically, the control valve <NUM> includes multiple control valves that control the flow of hydraulic oil discharged by the main pump <NUM>. The control valve <NUM> selectively supplies hydraulic oil discharged by the main pump <NUM> to one or more hydraulic actuators through the control valves. The control valves control the flow rate of hydraulic oil flowing from the main pump <NUM> to the hydraulic actuators and the flow rate of hydraulic oil discharged from the hydraulic actuators to a hydraulic oil tank.

The hydraulic actuators include the boom cylinder <NUM>, the arm cylinder <NUM>, the end attachment cylinder <NUM>, travel hydraulic motors <NUM>, and a swing hydraulic motor 2A. The travel hydraulic motors <NUM> include a left travel hydraulic motor <NUM> and a right travel hydraulic motor 20R.

The operating device <NUM> is a device that the operator uses to operate the hydraulic actuators. According to this embodiment, the operating device <NUM> is a hydraulic type and supplies hydraulic oil discharged by the control pump <NUM> to the pilot ports of the respective corresponding control valves of the hydraulic actuators through pilot lines.

The pressure of hydraulic oil supplied to each pilot port (hereinafter "pilot pressure") is a pressure commensurate with the direction of operation and the amount of operation of a lever or pedal constituting the operating device <NUM> corresponding to an individual hydraulic actuator. The operating device <NUM> may also be an electric type.

The solenoid valve <NUM> is placed in a conduit C0 between the control pump <NUM> and the motor regulators <NUM>. According to this embodiment, the solenoid valve <NUM> is a solenoid selector valve that switches the opening and closing of the conduit C0, and operates in response to a command from the controller <NUM>.

A pressure reducing valve <NUM> is placed in a conduit between the control pump <NUM>, and the operating device <NUM> and the solenoid valve <NUM>. According to this embodiment, the pressure reducing valve <NUM> reduces a pilot pressure and operates in response to a command from the controller <NUM>.

The discharge pressure sensor <NUM> is a sensor for detecting the discharge pressure of the main pump <NUM> and outputs a detected value to the controller <NUM>.

The operating pressure sensor <NUM> detects the details of the operator's operation using the operating device <NUM>. According to this embodiment, the operating pressure sensor <NUM> is, for example, a pressure sensor that detects the direction of operation and the amount of operation of a lever or pedal constituting the operating device <NUM> corresponding to an individual hydraulic actuator in the form of pressure, and outputs a detected value to the controller <NUM>.

The details of operation of the operating device <NUM> may also be detected using the output of a device other than a pressure sensor, such as an operating angle sensor, an acceleration sensor, an angular velocity sensor, a resolver, a voltmeter, or an ammeter. That is, the amount of operation of the operating device <NUM> may be expressed as not only an operating pressure but also an operating angle, the two integral value of operating acceleration, the integral value of operating angular velocity, a voltage value, a current value, or the like.

The controller <NUM> is a control device for controlling the work machine <NUM>. According to this embodiment, the controller <NUM> is constituted of a computer including a CPU, a volatile storage device, and a non-volatile storage device, for example. The controller <NUM>, for example, causes the CPU to execute programs corresponding to various functional elements such as a traveling mode control part <NUM>.

The switch <NUM> is a switch for switching the operating mode (traveling mode) of the motor regulators <NUM>. According to this embodiment, the switch <NUM> is a software switch displayed on an in-vehicle display with a touchscreen. The switch <NUM> may also be a hardware switch installed in the cab <NUM>.

The switch <NUM> is a switch for switching the operation of elevating the cab <NUM> and the operation of lowering the cab <NUM>. The switch <NUM> may be, for example, a hardware switch installed in the cab <NUM>, and switches the raising and the lowering of the cab <NUM> according to operation. Furthermore, according to this embodiment, the position of the cab <NUM> does not move without the operation of the switch <NUM>.

The motor regulators <NUM> control the displacements of the travel hydraulic motors <NUM>. According to this embodiment, the motor regulators <NUM> include a left motor regulator <NUM> and a right motor regulator 50R. The left motor regulator <NUM> controls the motor displacement of the left travel hydraulic motor <NUM> by adjusting the swash plate tilt angle of the left travel hydraulic motor <NUM> according to a control pressure generated by hydraulic oil supplied through the solenoid valve <NUM>. The same is the case with the right motor regulator 50R.

Specifically, the left motor regulator <NUM> can choose the motor displacement of the left travel hydraulic motor <NUM> between the two levels of a high rotation setting and a low rotation setting by choosing the swash plate tilt angle of the left travel hydraulic motor <NUM> between two levels.

The low rotation setting is implemented by increasing the motor displacement. In this case, the left travel hydraulic motor <NUM> operates with low rotation and high torque. The high rotation setting is implemented by decreasing the motor displacement. In this case, the left travel hydraulic motor <NUM> operates with high rotation and low torque. The same is the case with the right motor regulator 50R.

The controller <NUM> executes various processes as described below based on the outputs of the discharge pressure sensor <NUM>, the operating pressure sensor <NUM>, the switch <NUM>, etc., for example. Functions of the controller <NUM> are described in detail below.

Next, a hydraulic system installed in the work machine <NUM> is described with reference to <FIG> is a schematic diagram illustrating an example configuration of a hydraulic system installed in the work machine of <FIG>. The hydraulic system of <FIG> circulates hydraulic oil from main pumps <NUM> and 14R driven by the engine <NUM> to the hydraulic oil tank via center bypass conduits <NUM> and 40R and parallel conduits <NUM> and 42R. The main pumps <NUM> and 14R correspond to the main pump <NUM> of <FIG>.

The center bypass conduit <NUM> is a hydraulic oil line passing through control valves <NUM> through <NUM> arranged in the control valve <NUM>. The center bypass conduit 40R is a hydraulic oil line passing through control valves 171R through 175R arranged in the control valve <NUM>.

The control valve <NUM> is a spool valve that switches the flow of hydraulic oil to supply hydraulic oil discharged by the main pump <NUM> to the left travel hydraulic motor <NUM> and discharge hydraulic oil discharged by the left travel hydraulic motor <NUM> to the hydraulic oil tank.

The control valve 171R is a spool valve serving as a straight traveling valve. The control valve 171R switches the flow of hydraulic oil so that the hydraulic oil is supplied from the main pump <NUM> to each of the left travel hydraulic motor <NUM> and the right travel hydraulic motor 20R in order to increase the straightness of traveling of the lower traveling structure <NUM>. Specifically, when the travel hydraulic motors <NUM> and any other hydraulic actuator are simultaneously operated, the control valve 171R is switched so that the main pump <NUM> can supply hydraulic oil to each of the left travel hydraulic motor <NUM> and the right travel hydraulic motor 20R. When no other hydraulic actuators are operated, the control valve 171R is switched so that the main pump <NUM> can supply hydraulic oil to the left travel hydraulic motor <NUM> and the main pump 14R can supply hydraulic oil to the right travel hydraulic motor 20R.

The control valve <NUM> is a spool valve that switches the flow of hydraulic oil to supply hydraulic oil discharged by the main pump <NUM> to an optional hydraulic actuator and discharge hydraulic oil discharged by the optional hydraulic actuator to the hydraulic oil tank. The optional hydraulic actuator is, for example, a grapple opening and closing cylinder.

The control valve 171R is a spool valve that switches the flow of hydraulic oil to supply hydraulic oil discharged by the main pump 14R to the right travel hydraulic motor 20R and discharge hydraulic oil discharged by the right travel hydraulic motor 20R to the hydraulic oil tank.

The control valve <NUM> is a spool valve that switches the flow of hydraulic oil to supply hydraulic oil discharged by the main pump <NUM> to the swing hydraulic motor 2A and discharge hydraulic oil discharged by the swing hydraulic motor 2A to the hydraulic oil tank.

The control valve 173R is a spool valve that switches the flow of hydraulic oil to supply hydraulic oil discharged by the main pump 14R to the end attachment cylinder <NUM> and discharge hydraulic oil in the end attachment cylinder <NUM> to the hydraulic oil tank.

The control valves <NUM> and 174R are spool valves that switch the flow of hydraulic oil to supply hydraulic oil discharged by the main pumps <NUM> and 14R to the boom cylinder <NUM> and discharge hydraulic oil in the boom cylinder <NUM> to the hydraulic oil tank. According to this embodiment, the control valve <NUM> operates only when an operation to raise the boom <NUM> is performed, and does not operate when an operation to lower the boom <NUM> is performed.

The control valves <NUM> and 175R are spool valves that switch the flow of hydraulic oil to supply hydraulic oil discharged by the main pumps <NUM> and 14R to the arm cylinder <NUM> and discharge hydraulic oil in the arm cylinder <NUM> to the hydraulic oil tank.

The parallel conduit <NUM> is a hydraulic oil line parallel to the center bypass conduit <NUM>. When the flow of hydraulic oil through the center bypass conduit <NUM> is restricted or blocked by any of the control valves <NUM> through <NUM>, the parallel conduit <NUM> can supply hydraulic oil to a control valve further downstream. The parallel conduit 42R is a hydraulic oil line parallel to the center bypass conduit 40R. When the flow of hydraulic oil through the center bypass conduit 40R is restricted or blocked by any of the control valves 172R through 174R, the parallel conduit 42R can supply hydraulic oil to a control valve further downstream.

Pump regulators <NUM> and 13R control the discharge quantities of the main pumps <NUM> and 14R by adjusting the swash plate tilt angles of the main pumps <NUM> and 14R according to the discharge pressures of the main pumps <NUM> and 14R. The pump regulators <NUM> and 13R correspond to the pump regulator <NUM> of <FIG>. The pump regulators <NUM> and 13R decrease the discharge quantities of the main pumps <NUM> and 14R by adjusting their swash plate tilt angles when the discharge pressures of the main pumps <NUM> and 14R increase, for example. This is for preventing the absorbed power of the main pump <NUM> expressed as the product of discharge pressure and discharge quantity from exceeding the output power of the engine <NUM>.

A left travel operating device <NUM> and a right travel operating device 26R are examples of the operating device <NUM>, and are constituted of a travel operating lever and a travel operating pedal in combination.

The left travel operating device <NUM> is used to operate the left travel hydraulic motor <NUM>. The left travel operating device <NUM> uses hydraulic oil discharged by the control pump <NUM> to cause a pilot pressure commensurate with the amount of operation to act on a pilot port of the control valve <NUM>. Specifically, the left travel operating device <NUM> causes a pilot pressure to act on the left pilot port of the control valve <NUM> when operated in the forward traveling direction and causes a pilot pressure to act on the right pilot port of the control valve <NUM> when operated in the backward traveling direction.

The right travel operating device 26R is used to operate the right travel hydraulic motor 20R. The right travel operating device 26R uses hydraulic oil discharged by the control pump <NUM> to cause a pilot pressure commensurate with the amount of operation to act on a pilot port of the control valve 172R. Specifically, the right travel operating device 26R causes a pilot pressure to act on the right pilot port of the control valve 172R when operated in the forward traveling direction and causes a pilot pressure to act on the left pilot port of the control valve 172R when operated in the backward traveling direction.

In response to having received a communication command from the controller <NUM>, the solenoid valve <NUM> causes the control pump <NUM> to communicate with the motor regulators <NUM>. In this case, the motor regulators <NUM> operate in a forced fixed mode. In response to receiving no communication command from the controller <NUM>, the solenoid valve <NUM> interrupts the communication between the control pump <NUM> and the motor regulators <NUM>. In this case, the motor regulators <NUM> operate in a variable mode.

The pressure reducing valve <NUM> controls the amount of stroke (the amount of movement) of the spool of each of the control valves <NUM> and 172R in response to a command from the controller <NUM>. According to this embodiment, the pressure reducing valve <NUM> is not always necessary in the case of executing a flow rate reducing process with the travel hydraulic motors <NUM>, the main pump <NUM>, the engine <NUM>, etc..

Discharge pressure sensors <NUM> and 28R are examples of the discharge pressure sensor <NUM> of <FIG>. The discharge pressure sensor <NUM> detects the discharge pressure of the main pump <NUM> and outputs a detected value to the controller <NUM>. The discharge pressure sensor 28R detects the discharge pressure of the main pump 14R and outputs a detected value to the controller <NUM>.

Operating pressure sensors <NUM> and 29R are examples of the operating pressure sensor <NUM> of <FIG>. The operating pressure sensor <NUM> detects the details of the operator's operation on the left travel operating device <NUM> in the form of pressure, and outputs a detected value to the controller <NUM>. The operating pressure sensor 29R detects the details of the operator's operation on the right travel operating device 26R in the form of pressure, and outputs a detected value to the controller <NUM>. Examples of the details of operation include the direction of operation and the amount of operation (the angle of operation).

A boom operating lever, an arm operating lever, a bucket operating lever, and a swing operating lever (none of which is depicted) are operating devices for performing operations for raising and lowering the boom <NUM>, opening and closing the arm <NUM>, opening and closing the end attachment <NUM>, and swinging the upper swing structure <NUM>. The same as the left travel operating device <NUM>, these operating devices use hydraulic oil discharged by the control pump <NUM> to cause a pilot pressure commensurate with the amount of lever operation to act on the left or right pilot port of a control valve corresponding to an individual hydraulic actuator. Furthermore, the same as in the case of the operating pressure sensor <NUM>, the details of the operator's operation on each of these operating devices are detected by a corresponding operating pressure sensor in the form of pressure, and a detected value is output to the controller <NUM>.

Here, negative control (hereinafter "NC control") adopted in the hydraulic system of <FIG> is described.

The center bypass conduits <NUM> and 40R include negative control throttles <NUM> and 18R between the respective most downstream control valves <NUM> and 175R and the hydraulic oil tank. The flow of hydraulic oil discharged by the main pumps <NUM> and 14R is restricted by the negative control throttles <NUM> and 18R. The negative control throttles <NUM> and 18R generate control pressures (hereinafter "NC pressures") for controlling the pump regulators <NUM> and 13R.

NC pressure sensors <NUM> and 19R are sensors that detect the NC pressures generated upstream of the negative control throttles <NUM> and 18R. According to this embodiment, the NC pressure sensors <NUM> and 19R output detected values to the controller <NUM>.

The controller <NUM> outputs commands according to the NC pressures to the pump regulators <NUM> and 13R. The pump regulators <NUM> and 13R control the discharge quantities of the main pumps <NUM> and 14R by adjusting the swash plate tilt angles of the main pumps <NUM> and 14R according to the commands. Specifically, the pump regulators <NUM> and 13R decrease the discharge quantities of the main pumps <NUM> and 14R as the NC pressures increase, and increase the discharge quantities of the main pumps <NUM> and 14R as the NC pressures decrease.

When none of the hydraulic actuators is operated, hydraulic oil discharged by the main pumps <NUM> and 14R arrives at the negative control throttles <NUM> and 18R through the center bypass conduits <NUM> and 40R. The flow of the hydraulic oil discharged by the main pumps <NUM> and 14R increases NC pressures generated upstream of the negative control throttles <NUM> and 18R. As a result, the pump regulators <NUM> and 13R decrease the discharge quantities of the main pumps <NUM> and 14R to minimum allowable discharge quantities to control pressure loss (pumping loss) during the passage of the discharged hydraulic oil through the center bypass conduits <NUM> and 40R.

In contrast, when any of the hydraulic actuators is operated, hydraulic oil discharged by the main pump <NUM> or 14R flows into the operated hydraulic actuator via a control valve corresponding to the operated hydraulic actuator. The flow of the hydraulic oil discharged by the main pump <NUM> or 14R that arrives at the negative control throttle <NUM> or 18R is reduced in amount or lost, so that the NC pressure generated upstream of the negative control throttle <NUM> or 18R decreases. As a result, the pump regulator <NUM> or 13R increases the discharge quantity of the main pump <NUM> or 14R to circulate sufficient hydraulic oil to the operated hydraulic actuator to ensure the driving of the operated hydraulic actuator.

The above-described configuration enables the hydraulic system of <FIG> to control unnecessary energy consumption in the main pumps <NUM> and 14R when none of the hydraulic actuators is operated. The unnecessary energy consumption includes pumping loss that hydraulic oil discharged by the main pumps <NUM> and 14R causes in the center bypass conduits <NUM> and 40R. It is ensured that when a hydraulic actuator is operated, necessary and sufficient hydraulic oil is supplied from the main pump <NUM> or 14R to the operated hydraulic actuator.

Next, the motor regulators <NUM> are described with reference to <FIG> is a diagram illustrating an example configuration of a hydraulic circuit associated with motor regulators. The motor regulators <NUM> include the left motor regulator <NUM> and the right motor regulator 50R. In the following, a description is given of the left motor regulator <NUM>. The same description is also applied to the right motor regulator 50R.

The left motor regulator <NUM> mainly includes a first cylinder <NUM>, a second cylinder <NUM>, a swash plate link mechanism <NUM>, and a spring <NUM>, and is connected to a setting selector valve <NUM>.

The setting selector valve <NUM> is a valve for choosing the motor displacement of the left travel hydraulic motor <NUM> between the two levels of the high rotation setting and the low rotation setting. A first port 51aL of the setting selector valve <NUM> is connected to the secondary side of the solenoid valve <NUM>, and a second port 51bL of the setting selector valve <NUM> is connected to a shuttle valve <NUM>.

The shuttle valve <NUM> is configured to connect one of a conduit C1L and a conduit C2L that is higher in pressure to the second port 51bL of the setting selector valve <NUM>. The conduit C1L connects a first port 20aL of the left travel hydraulic motor <NUM> and the control valve <NUM>. The conduit C2L connects a second port 20bL of the left travel hydraulic motor <NUM> and the control valve <NUM>.

The setting selector valve <NUM> has a first valve position and a second valve position. The first valve position corresponds to the low rotation setting, and the second valve position corresponds to the high rotation setting. <FIG> illustrates the setting selector valve <NUM> in the first valve position.

In the first valve position, the setting selector valve <NUM> causes each of the first cylinder <NUM> and the second cylinder <NUM> to communicate with the hydraulic oil tank. In the second valve position, the setting selector valve <NUM> causes the first cylinder <NUM> to communicate with the conduit C1L and causes the second cylinder <NUM> to communicate with the conduit C2L.

The first cylinder <NUM> and the second cylinder <NUM> are hydraulic actuators that operate the swash plate link mechanism <NUM>. When connected to the hydraulic oil tank via the setting selector valve <NUM>, the first cylinder <NUM> and the second cylinder <NUM> discharge hydraulic oil in the cylinders to retract to operate the swash plate link mechanism <NUM> in a direction to increase the swash plate tilt angle.

As a result, according to this embodiment, the motor displacement of the left travel hydraulic motor <NUM> is maximized. In contrast, when connected to the conduits C1L and C2L via the setting selector valve <NUM>, the first cylinder <NUM> and the second cylinder <NUM> receive hydraulic oil into the cylinders to extend to operate the swash plate link mechanism <NUM> in a direction to decrease the swash plate tilt angle. As a result, according to this embodiment, the motor displacement of the left travel hydraulic motor <NUM> is minimized.

The spring <NUM> urges the swash plate link mechanism <NUM> in the direction to increase the swash plate tilt angle. When connected to the hydraulic tank via the setting selector valve <NUM>, the extended first cylinder <NUM> and second cylinder <NUM> retract while discharging hydraulic oil in the cylinders because of the restoring force of the spring <NUM>. As a result, the swash plate link mechanism <NUM> moves in the direction to increase the swash plate tilt angle to minimize the motor displacement of the left travel hydraulic motor <NUM>.

Next, a functional configuration of the controller <NUM> according to this embodiment is described with reference to <FIG> is a diagram illustrating a functional configuration of a controller.

The functions of the parts illustrated in <FIG> are implemented by the CPU of the controller <NUM> reading and executing programs stored in a storage such as the ROM.

The controller <NUM> according to this embodiment includes a position detecting part <NUM>, an operation detecting part <NUM>, the traveling mode control part <NUM>, a discharge quantity control part <NUM>, a rotational speed control part <NUM>, a stroke amount control part <NUM>, and a display control part <NUM>.

The position detecting part <NUM> detects the position of the cab <NUM>. The height of the cab <NUM> may be relative to the height of the cab in the state where the lowering of the cab <NUM> is completed.

Specifically, the position detecting part <NUM> according to this embodiment may detect the height of the cab <NUM> based on the output of the angle sensor <NUM>.

Furthermore, the position detecting part <NUM> according to this embodiment may also detect the position of the cab <NUM> based on an operation on the switch <NUM>. For example, the position detecting part <NUM> may detect the position (height) of the cab <NUM> according to the duration of a command to elevate the cab <NUM> input from the switch <NUM>.

The operation detecting part <NUM> detects an operation commanded for the work machine <NUM>. Specifically, the operation detecting part <NUM> detects an operation to elevate the cab <NUM> and an operation to lower the cab <NUM> based on an operation on the switch <NUM>. Furthermore, the operation detecting part <NUM> detects an operation to cause the work machine <NUM> to travel based on an operation on the operating device <NUM>.

The traveling mode control part <NUM> controls the traveling mode of the motor regulators <NUM>. According to this embodiment, the traveling mode includes the forced fixed mode (low speed mode) and the variable mode (high speed mode). In the forced fixed mode, the motor displacements of the travel hydraulic motors <NUM> are forcibly fixed to the low rotation setting. In the variable mode, the motor displacements can switch between the low rotation setting and the high rotation setting. The traveling mode may include a manual fixed mode. The manual fixed mode is, for example, a traveling mode that is set using the switch <NUM>. In the manual fixed mode, the motor displacements are fixed to the low rotation setting the same as in the case of the forced fixed mode.

For example, when a predetermined condition is satisfied, the traveling mode control part <NUM> outputs a command to the solenoid valve <NUM> to communicate the control pump <NUM> with the motor regulators. When the control pump <NUM> and the motor regulators <NUM> communicate, the motor regulators <NUM> operate in the forced fixed mode. In this case, the left motor regulator <NUM> fixes the motor displacement of the left travel hydraulic motor <NUM> to the low rotation setting, and the right motor regulator 50R fixes the motor displacement of the right travel hydraulic motor 20R to the low rotation setting.

Furthermore, the traveling mode control part <NUM> according to this embodiment fixes the traveling mode to the low speed mode when an operation that commands traveling is detected by the operation detecting part <NUM> while the position of the cab <NUM> detected by the position detecting part <NUM> is higher than a predetermined position.

A value indicating a predetermined height may be prestored in a storage device of the controller <NUM>. Furthermore, according to this embodiment, it may be determined that the position of the cab <NUM> is higher than a predetermined position when an angle detected by the angle sensor <NUM> is greater than or equal to a predetermined angle.

The traveling mode control part <NUM> according to this embodiment releases the traveling mode from the low speed mode when the position of the cab <NUM> detected by the position detecting part <NUM> becomes lower than or equal to the height of the predetermined position. That is, the traveling mode can be chosen between the high speed mode and the low speed mode in the work machine <NUM>.

According to this embodiment, the traveling mode is thus fixed at low speed (maintained at low speed) when the work machine <NUM> travels with the cab <NUM> being elevated to a position above a predetermined height.

Thus, according to this embodiment, it is possible to reduce shaking during the traveling of the work machine <NUM> with the elevated cab <NUM>.

Therefore, according to this embodiment, it is possible to reduce damage to a structure such as the cab riser <NUM> caused by shaking during traveling and control negative effects on the fatigue life of the structure caused by shaking during traveling.

Furthermore, according to this embodiment, when the cab <NUM> is elevated, traveling is performed at low speed. It is therefore possible to prevent an increase in the shaking of the cab <NUM> during traveling. Thus, according to this embodiment, it is possible to control the operator's fatigue and uncomfortable feeling due to shaking, so that it is possible to improve ride quality.

Furthermore, the discharge quantity control part <NUM> according to this embodiment may control the quantity of hydraulic oil discharged from the main pump <NUM> by controlling the pump regulator <NUM>. Furthermore, the rotational speed control part <NUM> according this embodiment controls the rotational speed of the engine <NUM>. The stroke amount control part <NUM> according to this embodiment may output a command to the pressure reducing valve <NUM> to control the amount of stroke of the spool of each of the control valves <NUM> and 172R.

Each of the discharge quantity control part <NUM>, the rotational speed control part <NUM>, and the stroke amount control part <NUM> according to this embodiment can fix the travel speed of the work machine <NUM> to low speed instead of the traveling mode control part <NUM> setting the traveling mode to the low speed mode.

For example, when an operation that commands traveling is detected while the position of the cab <NUM> is higher than a predetermined position, the discharge quantity control part <NUM> may restrict the quantity of hydraulic oil discharged from the main pump <NUM> so that the travel speed of the work machine <NUM> is fixed at low speed.

In other words, when an operation that commands traveling is detected while the cab <NUM> is at a position higher than a predetermined position, the discharge quantity control part <NUM> may restrict the flow rate of the main pump <NUM> to a predetermined proportion or less of the unrestricted flow rate.

The discharge quantity control part <NUM> removes the restriction on the discharge quantity when the position of the cab <NUM> becomes lower than or equal to the height of the predetermined position.

This makes it possible to produce the same effects as in the case where the traveling mode is set to the low speed mode by the traveling mode control part <NUM>.

Furthermore, when an operation that commands traveling is detected while the position of the cab <NUM> is higher than a predetermined position, the rotational speed control part <NUM> may restrict the rotational speed of the engine <NUM> so that the travel speed of the work machine <NUM> is fixed at low speed.

In other words, when an operation that commands traveling is detected while the cab <NUM> is at a position higher than a predetermined position, the rotational speed control part <NUM> may restrict the rotational speed of the engine <NUM> to a predetermined proportion or less of the unrestricted rotational speed.

The rotational speed control part <NUM> removes the restriction on the rotational speed when the position of the cab <NUM> becomes lower than or equal to the height of the predetermined position.

Furthermore, when an operation that commands traveling is detected while the position of the cab <NUM> is higher than a predetermined position, the stroke amount control part <NUM> outputs a command to the pressure reducing valve <NUM> to restrict the amount of stroke of the spool of each of the control valves <NUM> and 172R so that the travel speed of the work machine <NUM> is fixed at low speed.

In other words, when an operation that commands traveling is detected while the cab <NUM> is at a position higher than a predetermined position, the stroke amount control part <NUM> may restrict the amount of stroke of the spool of each of the control valves <NUM> and 172R to a predetermined proportion or less of the unrestricted amount of stroke.

The stroke amount control part <NUM> removes the restriction on the amount of stroke when the position of the cab <NUM> becomes lower than or equal to the height of the predetermined position.

According to this embodiment, the control for fixing the travel speed of the work machine <NUM> at low speed may be executed by one of the traveling mode control part <NUM>, the discharge quantity control part <NUM>, the rotational speed control part <NUM>, and the stroke amount control part <NUM>. Furthermore, the control part used for this control may be preset or may be determined by the controller <NUM> according to the state of the work machine <NUM>.

The display control part <NUM> according to this embodiment controls display on the display <NUM> provided in the cab <NUM>.

Specifically, the display control part <NUM> according to this embodiment displays a message indicating that the traveling mode is fixed to the low speed mode on the display <NUM> when the traveling mode is fixed to the low speed mode by the traveling mode control part <NUM>.

Next, a display example of the display <NUM> of the work machine <NUM> is described with reference to <FIG> is a diagram illustrating an example of an output image displayed on a display.

As illustrated in <FIG>, on a display screen Gx displayed on the display <NUM>, each of a time display area <NUM>, a rotational speed mode display area <NUM>, a traveling mode display area <NUM>, an attachment display area <NUM>, and an engine control status display area <NUM> is an example of a settings display area in which the settings of the work machine <NUM> are displayed. Each of a remaining aqueous urea solution amount display area <NUM>, a remaining fuel amount display area <NUM>, a coolant water temperature display area <NUM>, an engine operating time display area <NUM>, and a hydraulic oil temperature display area <NUM> is an example of an operating condition display area in which the operating condition of the work machine <NUM> is displayed.

Furthermore, on the display screen Gx, a camera image display area <NUM> is divided laterally into two. An image captured by a back monitoring camera 80B is displayed in a left camera image display area <NUM>, and an image captured by a right side monitoring camera 80R is displayed in a right camera image display area <NUM>. Furthermore, in <FIG>, various kinds of operating information are superimposed and displayed over the captured images in an upper area of the display screen Gx.

Images displayed in the parts are generated from various data transmitted from the controller <NUM> and camera images transmitted from the camera <NUM>.

Each camera is installed such that captured image data include at least part of a cover 3a of the upper swing structure <NUM>. The inclusion of part of the cover 3a in the displayed image allows the operator to have a better sense of distance between an object displayed in the camera image display area <NUM> and the work machine <NUM>.

The time display area <NUM> displays a current time. In the illustration of <FIG>, digital display is employed, and the current time (<NUM>:<NUM>) is shown.

The rotational speed mode display area <NUM> displays a rotational speed mode set by an engine rotational speed adjustment dial (not depicted) provided in the cab <NUM> in image form as operating information of the work machine. The rotational speed mode includes four modes that are SP mode, H mode, A mode, and idling mode. According to the illustration of <FIG>, a symbol "SP" representing SP mode is displayed.

The engine rotational speed adjustment dial allows the engine rotational speed to be selected from the four levels of SP mode, H mode, A mode, and idling mode.

The SP mode is a rotational speed mode selected when it is desired to prioritize workload, and uses the highest engine rotational speed. The H mode is a rotational speed mode selected when it is desired to balance workload and fuel efficiency, and uses the second highest engine rotational speed.

The A mode is a rotational speed mode selected when it is desired to operate the work machine at low noise while prioritizing fuel efficiency, and uses the third highest engine rotational speed.

The idling mode is a rotational speed mode selected when it is desired to idle the engine <NUM>, and uses the lowest engine rotational speed. The engine <NUM> is controlled to a constant rotational speed at the engine rotational speed of the rotational speed mode set by the engine rotational speed adjustment dial.

The traveling mode display area <NUM> displays a traveling mode as operating information of the work machine <NUM>. The traveling mode represents the setting of traveling hydraulic motors for which variable displacement motors are used.

For example, the traveling mode includes the low speed mode and the high speed mode. A "turtle"-shaped mark is displayed in the low speed mode, and a "rabbit"-shaped mark is displayed in the high speed mode. According to the illustration of <FIG>, the "turtle"-shaped mark is displayed to make it possible for the operator to recognize that the low speed mode is set.

The attachment display area <NUM> displays an image representing the attached attachment as operating information of the work machine.

The end attachment <NUM> attached to the work machine <NUM> varies from a bucket to a rock drill, a grapple, a lifting magnet, etc. The attachment display area <NUM> displays, for example, marks shaped like these end attachments and numbers corresponding to the attachments.

According to the illustration of <FIG>, a bucket is attached as the end attachment <NUM>, and the attachment display area <NUM> is blank as illustrated in <FIG>. When a rock drill is attached as the end attachment, for example, a rock drill-shaped mark is displayed together with a number representing the magnitude of the output of the rock drill in the attachment display area <NUM>.

The engine control status display area <NUM> displays the control status of the engine <NUM> as operating information of the work machine <NUM>. According to the illustration of <FIG>, "automatic deceleration and automatic stop mode" is selected as the control status of the engine <NUM>. The "automatic deceleration and automatic stop mode" means a control status to automatically reduce the engine rotational speed and further to automatically stop the engine <NUM> in accordance with the duration of a non-operating state. Other control statuses of the engine <NUM> include "automatic deceleration mode," "automatic stop mode," and "manual deceleration mode.

The remaining aqueous urea solution amount display area <NUM> displays the status of the remaining amount of an aqueous urea solution stored in an aqueous urea solution tank in image form as operating information of the work machine <NUM>. According to the illustration of <FIG>, a bar gauge representing the current status of the remaining amount of an aqueous urea solution is displayed. The remaining amount of an aqueous urea solution is displayed based on the output data of a remaining aqueous urea solution amount sensor provided in the aqueous urea solution tank.

The remaining fuel amount display area <NUM> displays the status of the remaining amount of fuel stored in a fuel tank as operating information. According to the illustration of <FIG>, a bar gauge representing the current status of the remaining amount of fuel is displayed. The remaining amount of fuel is displayed based on the output data of a remaining fuel amount sensor provided in the fuel tank.

The coolant water temperature display area <NUM> displays the temperature condition of engine coolant water as operating information of the work machine. According to the illustration of <FIG>, a bar gauge representing the temperature condition of engine coolant water is displayed. The temperature of engine coolant water is displayed based on the output data of a water temperature sensor provided on the engine <NUM>.

The engine operating time display area <NUM> displays the cumulative operating time of the engine <NUM> as operating information of the work machine <NUM>. According to the illustration of <FIG>, a cumulative operating time since the restart of counting by the operator is displayed together with a unit "hr (hour). " A lifelong operating time in the entire period after the manufacture of the work machine <NUM> or a section operating time since the restart of counting by the operator is displayed in the engine operating time display area <NUM>. The hydraulic oil temperature display area <NUM> is an area for displaying the temperature condition of hydraulic oil in the hydraulic oil tank. According to the illustration of <FIG>, a bar graph representing the temperature condition of hydraulic oil is displayed. The temperature of hydraulic oil is displayed based on the output data of an oil temperature sensor.

Furthermore, in the camera image display area <NUM>, an image capturing device icon 41n representing the orientation of the image capturing device <NUM> that has captured a captured image that is being displayed is displayed. The image capturing device icon 41n includes a work machine icon 41na representing the shape of the work machine <NUM> in a plan view and a strip-shaped orientation indicator icon 41nb representing the orientation of the image capturing device <NUM> that has captured the captured image that is being displayed.

In the left camera image display area <NUM>, an image capturing device icon 41n1 is displayed, and an orientation indicator icon 41n1b is displayed below a work machine (shovel) icon 41n1a, indicating that a captured image captured by the back monitoring camera 80B is being displayed. Furthermore, in the right camera image display area <NUM>, an image capturing device icon 41n2 is displayed, and an orientation indicator icon 41n2b is displayed to the right of a work machine (shovel) icon 41n2a, indicating that a captured image captured by the right side monitoring camera 80R is being displayed.

A captured image captured by a left side monitoring camera <NUM> may be displayed in the left camera image display area <NUM>, and a captured image captured by the back monitoring camera 80B may be displayed in the right camera image display area <NUM>. Furthermore, the camera image display area <NUM> may be divided into three, and an image captured by the left side monitoring camera <NUM>, an image captured by the back monitoring camera 80B, and an image captured by the right side monitoring camera 80R may be displayed in the left area, the central area, and the right area, respectively.

Furthermore, a composite image of multiple camera images captured by at least two among the left side monitoring camera <NUM>, the back monitoring camera 80B, and the right side monitoring camera 80R may be displayed in the camera image display area <NUM>. The composite image may be, for example, an overhead view image.

For example, by pressing an image change switch provided in the cab <NUM>, the operator can switch an image to display in the camera image display area <NUM> to an image captured by another camera, or the like.

When the camera <NUM> is not provided on the work machine <NUM>, different information may be displayed instead of the camera image display area <NUM>.

Furthermore, on the display screen Gx, a message display area <NUM> displays a message indicating that the travel speed of the work machine <NUM> is fixed at low speed.

According to the illustration of <FIG>, a message "FIXED AT LOW SPEED" is displayed. According to this embodiment, when the control for fixation to low speed is executed by the traveling mode control part <NUM>, a message "FIXED TO LOW SPEED MODE" may be displayed.

According to this embodiment, by displaying such a message, it is possible to cause the operator to recognize that the travel speed of the work machine <NUM> is fixed at low speed.

The above-described embodiment may be applied to any work machine to the extent that the work machine includes an elevating cab.

Claim 1:
A work machine (<NUM>) comprising:
an elevating cab (<NUM>);
a detection part (<NUM>) configured to detect a position of the elevating cab (<NUM>);
characterized by a control part (<NUM>, <NUM>, <NUM>, <NUM>) configured to fix the travel speed of the work machine (<NUM>) to low speed when a traveling operation is performed while the position of the elevating cab (<NUM>) detected by the detection part (<NUM>) is higher than a predetermined height.