WORKING MACHINE

The working machine includes a machine body, an engine provided on the machine body, a motor generator to be operated as a motor to assist driving of the engine in an assisting operation and to be operated as a generator by power of the engine to generate electricity in a generating operation, a battery to store the electricity generated by the motor generator, an acceleration sensor to measure acceleration of the machine body, and a controller to selectively set either one of the assisting operation and the generating operation based on the acceleration of the machine body measured by the acceleration sensor.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a working machine such as a compact track loader or a skid steer loader.

Description of the Related Art

Japanese Patent Publication No. 3941951 is known, which discloses a hybrid type working machine including an engine and a motor generator among working machines such as a compact track loader. In the working machine of Japanese Patent Publication No. 3941951, when an operation-mode judgment means determines that a hydraulic-operating portion is in the working mode, an electric motor generator controller means obtains a powering torque value to be output to the electric motor generator with reference to an actual engine revolving speed detected by an engine revolving speed detector means based on a powering torque output information obtained by relating, to the engine revolving speed, the powering torque output characteristics of the electric motor generator, which is set according to the current working mode.

In Japanese Patent Publication No. 3941951, when a remaining amount of power storage detected by a remaining power-storage detector means is less than a predetermined value, the powering torque value obtained above is limited according to a remaining amount of power storage, and a driving signal is output to an inverter so that the electric motor generator outputs a limited powering torque value.

In addition, a working machine of Japanese Unexamined Patent Application Publication No. 2009-174446 includes an assist torque adding means to add an assist torque on an output torque, and an overloading state judgment means to judge whether an overloading state in which an input torque exceeds an output torque occurs, and further the assist torque adding means adds the assist torque on the output torque when it is judged the overloading state is occurring presently.

SUMMARY OF THE INVENTION

A working machine of the present invention includes a machine body, an engine provided on the machine body, a motor generator to be operated as a motor to assist driving of the engine in an assisting operation and to be operated as a generator by power of the engine to generate electricity in a generating operation, a battery to store the electricity generated by the motor generator, an acceleration sensor to measure acceleration of the machine body, and a controller to selectively set either one of the assisting operation and the generating operation based on the acceleration of the machine body measured by the acceleration sensor.

The controller estimates, based on the acceleration of the machine body measured by the acceleration sensor, what kind of traveling state the machine body is in, and performs the selective setting based on the estimated traveling state.

When a fore-and-aft directional acceleration of the machine body is not less than a threshold, the controller estimates that the machine body is in a straight traveling state where the machine body is traveling straight. When the fore-and-aft directional acceleration of the machine body is less than the threshold, the controller estimates that the machine body is in a non-straight traveling state defined as any traveling state other than the straight traveling state. The controller selectively sets either one of the assisting operation and the generating operation based on whether the traveling state is estimated as the straight traveling state or the non-straight traveling state.

The controller estimates, based on a width directional acceleration of the machine body and on a yaw rate of the machine body, whether the machine body is in a turning state where the machine body is turning or not. The controller selectively sets either one of the assisting operation and the generating operation based on whether or not the traveling state is estimated as the turning state.

The controller includes a powering torque setting unit to set a powering torque of the motor generator in the assisting operation, a regenerating torque setting unit to set a regenerating torque of the motor generator in the generating operation, and an operation control unit to perform the assisting operation at the powering torque set by the powering torque setting unit when a revolving speed of the engine is not higher than a first revolving speed, and to perform the generating operation at the regenerating torque set by the regenerating torque setting unit when the revolving speed of the engine is not lower than a second revolving speed that is higher than the first revolving speed.

Either one of the powering torque setting unit and the regenerating torque setting unit changes the setting of corresponding one of the powering torque and the regenerating torque based on the acceleration of the machine body.

The controller changes either the first revolving speed or the second revolving speed based on the acceleration of the machine body.

A working machine includes a machine body, an engine provided on the machine body, a motor generator to be operated as a motor to assist driving of the engine in an assisting operation, and to be operated as a generator by power of the engine to generate electricity in a generating operation, a battery to store the electricity generated by the motor generator, a cooling device to cool the battery with the power transmitted from the engine, a hydraulic driving device to which the powers of the engine and the motor generator are transmitted, a working device to be operated by power of the hydraulic driving device, and a traveling device to be operated by the power of the hydraulic driving device. The cooling device stops based on an operating state of either one of the hydraulic diving device, the working device, and the traveling device.

The working machine includes a load detector to detect a load of either one of the hydraulic diving device, the working device, and the traveling device. The cooling device stops when the load detected by the load detector is a predetermined load or more.

The working machine includes an operation member to operate either one of the working device and the traveling device. The cooling device stops when an operation extent of the operation member is a predetermined extent or more.

The working machine includes a temperature detector to detect temperature of the battery. The cooling device does not stop when the temperature detected by the temperature detector is a predetermined temperature or more.

The cooling device includes an evaporator through which coolant to cool the battery flows, and a compressor to compress the coolant that has flown through the evaporator. The compressor stops based on the operating state.

The hydraulic driving device includes a hydraulic pump, and the working device includes a boom swingably provided on the machine body, and a boom cylinder to be operated by hydraulic fluid delivered from the hydraulic pump to swing the boom.

A working machine includes a machine body, an engine provided on the machine body, a motor generator to be operated as a motor to assist driving of the engine in an assisting operation and to be operated as a generator by power of the engine to generate electricity in a generating operation, a battery to store the electricity generated by the motor generator, a traveling device to be operated by powers of at least the engine and the motor generator, and a controller configured so that, in a state where the motor generator is in the assisting operation, the controller stops or limits the assisting operation when an outputting condition relating to outputting from the traveling device deviates from that corresponding to an inputting condition relating to inputting to the traveling device.

The working machine includes a traveling operation member to operate the traveling device, and a rotation detector to detect a rotation speed of the traveling device. When the inputting condition is an operation extent of the traveling operation member and the outputting condition is the rotation speed detected by the rotation detector, the controller stops or limits the assisting operation when the rotation speed of the traveling device is lower than that corresponding to the operation extent.

The working machine includes a traveling operation member to operate the traveling device, and a rotation detector to detect a rotation speed of the traveling device. When the inputting condition is an operation extent of the traveling operation member and the outputting condition is the rotation speed detected by the rotation detector, the controller stops or limits the assisting operation when the rotation speed of the traveling device is higher than that corresponding to the operation extent.

The working machine includes a traveling operation member to operate the traveling device, and a vehicle-speed detector to detect a vehicle speed of the machine body. When the inputting condition is an operation extent of the traveling operation member and the outputting condition is the vehicle speed detected by the vehicle-speed detector, the controller stops or limits the assisting operation when the vehicle speed is lower than that corresponding to the operation extent.

The working machine includes a traveling operation member to operate the traveling device, and a vehicle-speed detector to detect a vehicle speed of the machine body. When the inputting condition is an operation extent of the traveling operation member and the outputting condition is the vehicle speed detected by the vehicle-speed detector, the controller stops or limits the assisting operation when the vehicle speed is higher than that corresponding to the operation extent.

The controller includes a powering torque setting unit to set a powering torque of the motor generator in the assisting operation, a regenerating torque setting unit to set a regenerating torque of the motor generator in the generating operation, and an operation control unit to perform the assisting operation at the powering torque set by the powering torque setting unit when a revolving speed of the engine is not higher than a first revolving speed, and to perform the generating operation at the regenerating torque set by the regenerating torque setting unit when the revolving speed of the engine is not lower than a second revolving speed that is higher than the first revolving speed.

The powering torque setting unit reduces the powering torque when the deviation occurs.

The powering torque setting unit increases the powering torque when a load on the engine increases. The power torque setting unit reduces the powering torque when the load on the engine reduces.

The working machine includes a detection sensor to detect the revolving speed of the engine. The powering torque setting unit increases the powering torque when the revolving speed of the engine detected by the detection sensor increases. The powering torque setting unit reduces the powering torque when the revolving speed of the engine reduces.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to drawings, a working machine according to an embodiment of the present invention will be described below.

FIG. 1shows a side view of a working machine1of the present invention. InFIG. 1, a compact track loader is illustrated as an example of a working machine. However, the working machine is not limited to a compact track loader, but may be another typed loader, such as a skid steer loader, for example. In addition, it may also be a working machine other than the loader. In description of the present invention, a forward direction of an operator seating on a driver seat of the working machine (the left side inFIG. 1) is referred to as the front, a rearward direction of the operator (the right side inFIG. 1) is referred to as the rear, a left direction of the operator (the front surface side ofFIG. 1) is referred to as the left, and a right direction of the operator (the back surface side ofFIG. 1) is referred to as the right. A direction orthogonal to the forward and rearward directions of a machine body may be referred to as a machine width direction (also referred to as a width direction).

The working machine1includes a machine body2, a working device3, and a pair of traveling devices4L and4R.

A cabin5is mounted on an upper front portion of the machine body2. A rear portion of the cabin5is supported by a bracket of the machine body2pivotally around a support shaft. A front portion of the cabin5is configured to be mounted on a front portion of the machine body2. A driver seat7is provided in the cabin5.

The pair of traveling devices4L and4R are constituted of crawler-type traveling devices. The traveling device4L is installed on one side (left side) of the machine body2, and the traveling device4R is installed on the other side (right side) of the machine body2.

The working device3includes booms10, boom cylinders14, working tool cylinders15, and a working tool11. The booms10are supported by lift links12and control links13. Each of the boom cylinders14, which consists of a double-acting hydraulic cylinder, is interposed between a base portion of the corresponding boom10and a rear lower portion of the machine body2. By simultaneously extending and contracting the boom cylinders14, the booms10are pivoted up and down.

At a tip end of the boom10, each of attachment brackets18is supported pivotally around a horizontal axis, and the back surface of the working tool11is attached to the left and right attachment brackets18. That is, the working tool11is attached to the tip ends of the booms10.

Each of the working tool cylinders15, which is a double-acting hydraulic cylinder, is interposed between the corresponding attachment bracket18and a middle portion of the tip end of the corresponding boom10. The extending and contracting of the working tool cylinders15swing the working tool11(the scooping and dumping operations).

The working tool11is configured to be attached to and detached from the attachment brackets18. The working tool11is, for example, an attachment (auxiliary attachment) such as a bucket, a hydraulic crusher, a hydraulic breakers, an angle broom, an earth auger, a pallet fork, a sweeper, a mower, or a snow blower.

Next, the machine body will be described.

As shown inFIG. 2, the machine body2has a right frame portion20, a left frame portion21, a front frame portion22, a bottom frame portion23, and an upper frame portion24.

The right frame portion20constitutes a right portion of the machine body2. The left frame portion21constitutes a left portion of the machine body2. The front frame portion22constitutes a front portion of the machine body2, and connects front portions of the right frame portion20and the left frame portion21with each other. The bottom frame portion23constitutes a bottom portion of the machine body2, and connects lower portions of the right frame portion20and the left frame portion21with each other. An upper frame portion24constitutes a rearward upper portion of the machine body2, and connects upper rearward portions of the right frame portion20and the left frame portion21with each other.

Rear portions of the right frame portion20and the left frame portion21swingably support the booms10and the like. Each of the right frame portion20and the left frame portion21is provided with a track frame25and a motor attachment portion26.

As shown inFIG. 3, an engine60, a cooling fan61, a radiator, a motor generator63, and a hydraulic driving device64is installed on the machine body2. The engine60is an internal combustion engine such as a diesel engine or a gasoline engine. The cooling fan61is driven by the power of the engine60, and the radiator cools cooling water for cooling the engine60. The motor generator63is a device configured to be operated as a motor to assist driving of the engine60in an assisting operation and to be operated as a generator by power of the engine to generate electricity in a generating operation. The motor generator63is constituted of a permanent magnet embedded three-phase AC synchronous motor.

The hydraulic driving device64is a device configured to be driven by powers/power of the engine60and/or the motor generator63, and mainly outputs power for working. The hydraulic driving device64is located in front of the motor generator63. The hydraulic driving device64includes a plurality of hydraulic pumps, and, as shown inFIGS. 5 and 6, the plurality of hydraulic pumps include a traveling pump52L, a traveling pump52R, a sub pump P1, and a main pump P2, for example.

In addition, a battery66and an electric power controller67are provided on the machine body2.

The battery66stores an electric power generated by the motor generator63, and supplies the stored electric power to the motor generator63and other devices.

The working machine1is configured to drive the hydraulic driving device64by power of the engine60, to drive the hydraulic driving device64with both the engine60and the motor generator63, and to operate the motor generator63by power of the engine60so as to generate electricity. That is, transmission of power to the working device is performed in a parallel hybrid system. A power transmission structure of the engine60and the motor generator63will be described below.

As shown inFIGS. 3 and 4, a housing65is located on a front portion of the engine60, the housing65houses a flywheel having a substantially-discoidal shape and the motor generator63. The motor generator63includes a coupler portion63aconnecting to the flywheel, a rotor63bfixed to the coupler portion63a, a stator63cprovided on the rotor63b, and a water jacket63dprovided on an outside of the stator63c.

The coupler portion63ais formed to have a cylindrical shape, and has a rear end attached to the flywheel. An intermediate shaft68ais provided inside the coupler portion63a. A coupler68bis located at the rear end of the intermediate shaft68a, and an outer side of the coupler68bis connected to the flywheel. In addition, a front end of the intermediate shaft68ais connected to a drive shaft of the hydraulic driving device64.

Thus, when the engine60is driven, a rotational power of the crankshaft (output shaft)60aof the engine60is transmitted to the flywheel to rotate the flywheel. As shown by an arrowed line F1inFIG. 4, a rotational power of the flywheel is transmitted from the coupler68bto the intermediate shaft68a, and then transmitted from the intermediate shaft68ato the drive shaft of the hydraulic driving device64to drive the hydraulic driving device64.

In addition, as shown by an arrowed line F2inFIG. 4, a rotational power of the flywheel is transmitted to the rotor63bthrough the coupler portion63a. Thus, when a rotational power of the engine60is transmitted to the rotor63b(and the coupler portion63a), the motor generator63can be operated as a generator. On the other hand, when an electric power stored in the battery66is supplied to the stator63c, the rotor63bcan be rotated. As shown by an arrowed line F3, a rotational power of the rotor63bcan be transmitted to the flywheel through the coupler portion63a. Thus, the motor generator63can be operated as an electric motor to assist the engine60.

FIGS. 5 and 6show respective hydraulic circuits (hydraulic systems) of the working device.FIG. 5shows a hydraulic system for traveling, andFIG. 6shows a hydraulic system for working.

As shown inFIG. 5, the hydraulic system for traveling is a system configured to operate the traveling devices4L and4R with a hydraulic pressure generated when the hydraulic driving device64is driven. The hydraulic system for traveling includes a sub pump P1, which is a hydraulic pump to deliver hydraulic fluid, a first traveling motor mechanism31L, a second traveling motor mechanism31R, and a traveling driving mechanism34.

The sub pump P1is constituted of a constant-displacement gear pump. The sub pump P1is configured to deliver hydraulic fluid stored in a tank (hydraulic fluid tank). A delivery fluid line40through which hydraulic fluid flows is extended from a delivery port of the sub pump P1. A first charging fluid line41is connected to a delivery side of the delivery fluid line40. The first charging fluid line41extends to the traveling driving mechanism34. Of hydraulic fluid delivered from the sub pump P1, the hydraulic fluid to be used for control may be referred to as a pilot fluid, and a pressure of the pilot fluid may be referred to as a pilot pressure.

The traveling driving mechanism34is a mechanism configured to drive the first traveling motor mechanism31L and the second traveling motor mechanism31R, and includes a drive circuit34L for driving the first traveling motor mechanism31L (referred to as a left drive circuit) and a drive circuit34R for driving the second traveling motor mechanism31R (referred to as a right drive circuit).

The drive circuits34L and34R respectively include traveling pumps52L and52R, shift fluid lines57hand57i, and respective second charging fluid lines42. The shift fluid lines57hand57iare fluid lines respectively connecting the traveling pumps52L and52R to the traveling motors36L and36R. The second charging fluid lines42are fluid lines connected to the respective shift fluid lines57hand57iand configured to supply hydraulic fluid, which is supplied from the sub pump P1, to the shift fluid lines57hand57i. Each of the traveling pumps52L and52R is constituted of a variable displacement axial pump of swash plate type to be driven by the power of the engine60. Each of the traveling pumps52L and52R includes a pressure receiver portion52aand a pressure receiver portion52bon which a pilot pressure is applied, and changes an angle of a swash plate with the pilot pressure applied on the pressure receiver portions52aand52b. When an angle of the swash plate is changed, outputs (output rates of the hydraulic fluid) of the traveling pumps52L and52R and an output direction of hydraulic fluid can be changed. In other words, the traveling pumps52L and52R changes an angles of the swash plates to change a driving forces to be output to the traveling devices4L and4R.

The first traveling motor mechanism31L is a mechanism configured to transmit power to the drive shaft of the traveling device4L that is installed leftward on the machine body2. The second traveling motor mechanism31R is a mechanism configured to transmit power to the drive shaft of the traveling device4R that is installed rightward on the machine body2. The traveling motor mechanisms31L and31R include the traveling motors36L and36R and a speed shifter mechanism.

Each of the traveling motors36L and36R is a variable displacement axial pump of swash plate type, for example. The traveling motor36L is attached to the motor attachment portion26located on the left frame portion21, and provides a traveling power to the traveling device4L. The traveling motor36R is attached to the motor attachment portion26located on the right frame portion20, and provides a traveling power to the traveling device4R. The traveling motors36L and36R are motors configured to change a vehicle speed (that is, a rotating speed) between a first speed and a second speed. In other words, the traveling motors36L and36R are motors capable of changing a force of propelling the working machine1, that is, the traveling devices4L and4R.

Each speed shifter mechanism includes a swash plate switching cylinder38aand a traveling switching valve38b. The swash plate switching cylinder38ais telescopically movable to change an angle of the corresponding swash plate of each of the traveling motors36L and36R. The traveling switching valve38bis a valve to extend and contract the swash plate switching cylinder38ain one and the other directions, that is, a two-position switching valve configured to be switched between a first position39aand a second position39b. The traveling switching valves38bare switched by a speed-shifting switching valve44. The speed-shifting switching valve44is connected to the delivery fluid line40, and is connected to the traveling switching valve38bof the first traveling motor mechanism31L and to the traveling switching valve38bof the second traveling motor mechanism31R. The speed-shifting switching valve44is a two-position switching valve configured to be switched between a first position44aand a second position44b. When the speed-shifting switching valve44is set to the first position44a, a pressure of the hydraulic fluid to be applied to the traveling switching valve38bof the speed shifter mechanism is set as a pressure corresponding to a predetermined speed (for example, a first speed). When the speed-shifting switching valve44is set to the first position44a, a pressure of the hydraulic fluid to be applied to the traveling switching valve38bis set as another pressure corresponding to another speed (a second peed) faster than the predetermined speed (the first speed). Thus, when the speed-shifting switching valve44is in the first position44a, the traveling switching valves38bare in the respective first positions39a, and accordingly the swash plate switching cylinders38aare contracted to set the traveling motors36L and36R in the first speed state. When the speed-shifting switching valve44is in the second position44b, the traveling switching valve38bis in the second position39b, and accordingly the swash plate switching cylinder38ais extended to set the traveling motors36L and36R in the second speed state. The shifting of the traveling motors36L and36R between the first speed state and the second speed state is controlled by a working controller70. For example, the working controller70is provided with an operation member58such as a switch (a speed shifter switch) (see FIG.8). When the operation member58is switched to set the first speed, the working controller70outputs a control signal to demagnetize a solenoid of the speed-shifting switching valve44to set the speed-shifting switching valve44to the first position44a. When the operation member58is switched to set the second speed, the working controller70outputs a control signal to magnetize a solenoid of the speed-shifting switching valve44to set the speed-shifting switching valve44to the second position44b.

As shown inFIG. 5, the working machine1is provided with an operation device53. The operation device53is a device configured to operate the traveling devices4L and4R, that is, the first traveling motor mechanism31L, the second traveling motor mechanism31R, and the traveling driving mechanism34. The operation device53includes a traveling operation member54and a plurality of operation valves55(55a,55b,55c, and55d). The plurality of operation valves55(55a,55b,55c, and55d) are traveling operation valves.

The traveling operation member54is an operation member supported by the operation valves55, and is configured to swing in a left-and-right direction (a machine width direction) or a fore-and-aft direction. The plurality of operation valves55are operated by the common traveling operation member54, i.e., by the single traveling operation member54. The plurality of operation valves55are actuated according to the swinging of the traveling operation member54. To the plurality of operation valves55, hydraulic fluid (the pilot fluid) delivered from the sub pump P1can be supplied through the delivery fluid line40. The plurality of operation valves55include the operation valve55a, the operation valve55b, the operation valve55c, and the operation valve55d.

The plurality of operation valves55are connected to the traveling driving mechanism34(traveling pumps52L and52R) via traveling fluid lines45. The traveling fluid lines45include a first traveling fluid line45a, a second traveling fluid line45b, a third traveling fluid line45c, a fourth traveling fluid line45d, and a fifth traveling fluid line45e. The first traveling fluid line45ais a fluid line connected to the pressure receiver portion52aof the traveling pump52L. The second traveling fluid line45bis a fluid line connected to the pressure receiver portion52bof the traveling pump52L. The third traveling fluid line45cis a fluid line connected to the pressure receiver portion52aof the traveling pump52R.

The fourth traveling fluid line45dis a fluid line connected to the pressure receiver portion52bof the traveling pump52R. The fifth traveling fluid line45eis a fluid line that connects the operation valve55, the first traveling fluid line45a, the second traveling fluid line45b, the third traveling fluid line45c, and the fourth traveling fluid line45dto each other. The fifth traveling fluid line45econnects shuttle valves46to the operation valves55(55a,55b,55c, and55d), respectively.

When the traveling operation member54is pivoted forward (in a direction indicated by an arrowed line A1inFIG. 5), the operation valve55ais operated so as to apply pilot pressures to the pressure receiver portions52aof the traveling pumps52L and52R to tilt the swash plates of the traveling pumps52L and52R in respective normal rotation directions from respective neutral positions, and in this state, the traveling pumps52L and52R deliver hydraulic fluid. As the result, the output shafts35L and35R of the traveling motors36L and36R normally rotate (rotate forward) at a speed proportional to a pivoting extent of the traveling operation member54, and thus the working machine1moves straight forward.

When the traveling operation member54is pivoted backward (in a direction indicated by an arrowed line A2inFIG. 5), the operation valve55bis operated so as to apply pilot pressures to the pressure receiver portions52bof the traveling pumps52L and52R to tilt the swash plates of the traveling pumps52L and52R in respective reverse rotation directions from the respective neutral positions, and in this state, the traveling pumps52L and52R deliver hydraulic fluid. As the result, the output shafts35L and35R of the traveling motors36L and36R reversely rotate (rotate backward) at a speed proportional to a pivoting extent of the traveling operation member54, and thus the working machine1moves straight backward.

When the traveling operation member54is pivoted rightward (in a direction indicated by an arrowed line A3inFIG. 5), the operation valve55cis operated so as to apply pilot pressures to the pressure receiver portion52aof the traveling pump52L and the pressure receiver portion52bof the traveling pump52R, respectively, to tilt the swash plate of the traveling pump52L in the normal rotation direction, and the swash plate of the traveling pump52R in the reverse rotation direction, respectively. As the result, the output shaft35L of the traveling motor36L located on the left side normally rotates and the output shaft35R of the traveling motor36R located on the right side reversely rotates, and thus the working machine1turns to the right (ultra-pivotal turn). When the traveling operation member54is pivoted leftward (in a direction indicated by an arrowed line A4inFIG. 5), the operation valve55dis operated so as to apply pilot pressures to the pressure receiver portion52bof the traveling pump52L and the pressure receiver portion52aof the traveling pump52R, respectively, to tilt the swash plate of the traveling pump52L in the reverse rotation direction, and the swash plate of the traveling pump52R in the normal rotation direction, respectively. As the result, the output shaft35L of the traveling motor36L located on the left side reversely rotates and the output shaft35R of the traveling motor36R located on the right side normally rotates, and thus the working machine1turns to the left (ultra-pivotal turn).

When the traveling operation member54is pivoted in an oblique direction, the rotational directions and the rotation speeds of the output shafts35L and35R of the left traveling motor36L and the right traveling motor36R are determined based on a differential pressure between the pilot pressures applied to the pressure receiver portion52aand the pressure receiver portion52b, and then the working machine1turns right (the right pivotal turn) or left (the left pivotal turn) in forward traveling or reverse traveling.

The working machine1may be provided with an anti-stall control valve48. The anti-stall control valve48is located in the fluid line (delivery fluid line40) between the plurality of operation valves55(55a,55b,55c, and55d) and the sub pump P1.

The anti-stall control valve48is a proportional solenoid valve having a variable aperture. The anti-stall control valve48is capable of setting a pilot pressure (referred to as a primary pilot pressure) applied to the plurality of operation valves55(55a,55b,55c, and55d) based on a reduction amount (dropping) ΔE1of a revolving speed of the engine60(referred to as an engine revolving speed). The revolving speed of the engine can be detected by a sensor91for detecting an engine revolving speed. The engine revolving speed detected by the sensor91is input to the working controller70.

FIG. 7shows a relationship between the engine revolving speed, the primary traveling pressure (that is, the primary pilot pressure), and setting lines L51and L52. The setting line L51shows a relationship between the engine revolving speed and the primary traveling pressure when a reduction amount ΔE1is less than a predetermined value (i.e., less than an anti-stall judgment value). The setting line L52shows a relationship between an engine revolving speed and the primary traveling pressure when the reduction amount ΔE1is equal to or more than the anti-stall judgment value.

The working controller70adjusts an opening aperture of the anti-stall control valve48so that the relationship between the engine revolving speed and the primary traveling pressure matches with the reference pilot pressure indicated by the setting line L51when the reduction amount ΔE1is less than the anti-stall judgment value. When the reduction amount ΔE1is equal to or more than the anti-stall judgment value, the working controller70adjusts the opening aperture of the anti-stall control valve48so that the relationship between the engine revolving speed and the primary traveling pressure matches with the setting line L52, which indicates a pressure lower than the reference pilot pressure. On the setting line L52, the primary traveling pressure for a predetermined engine speed is lower than the primary traveling pressure of the setting line L51. That is, when focusing on the same engine speed, the primary traveling pressure of the setting line L52is set lower than the primary traveling pressure of the setting line L51. Thus, a pressure of the hydraulic fluid (that is, the pilot pressure) to enter the operation valve55is kept low under the control based on the setting line L52. As the result, the swash plate angles of the traveling pumps52L and52R are adjusted, and the load applied to the engine is reduced, thereby preventing the engine from stalling. AlthoughFIG. 7shows the setting line L52as a single line, the setting line L52may be considered as a plurality of lines. For example, the setting line L52may be set for each engine revolving speed. It is preferable that the working controller70has data indicating the setting lines L51and L52or control parameters such as functions.

Next, the hydraulic system for working will be described.

As shown inFIG. 6, the hydraulic system for working is a system configured to operate the working device3and the like. The hydraulic system for working is a system configured to operate the working device3with the hydraulic pressure generated when the hydraulic driving device64is driven. The hydraulic system for working is provided with a plurality of control valves51and the main pump P2that is a hydraulic pump configured to deliver hydraulic fluid. The main pump P2is a pump located at a position different from a position of the sub pump P1, and is constituted of a small-displacement gear pump. The main pump P2is configured to deliver the hydraulic fluid stored in a hydraulic fluid tank. In particular, the main pump P2delivers hydraulic fluid that mainly operates the hydraulic actuators.

A fluid line51fis extended from a delivery port of the main pump P2. The plurality of control valves51are connected to this fluid line51f. The plurality of control valves51include a boom control valve51a, a bucket control valve51b, and an auxiliary control valve51c. The boom control valve51ais configured to control the boom cylinder14, the bucket control valve51bis configured to control the working tool cylinder15, and the auxiliary control valve51cis configured to control the hydraulic actuator of the auxiliary attachment.

Operations of the boom10and the working tool11can be performed by a working operation member37included in the operation device43. The working operation member37is an operation member supported by a plurality of operation valves59and configured to swing in a left-and-right direction (that is, the machine width direction) or the fore-and-aft direction. By operating to tilt the working operation member37, the operation valves59located on the lower portion of the working operation member37can be operated.

The plurality of operation valves59are fluidly connected to the plurality of control valves51via a plurality of working fluid lines47(47a,47b,47c, and47d), respectively. In particular, the operation valve59ais connected to the boom control valve51athrough the working fluid line47a. The operation valve59bis connected to the boom control valve51athrough the working fluid line47b. The operation valve59cis connected to the bucket control valve51bthrough the working fluid line47c. The operation valve59dis connected to the bucket control valve51bthrough the working fluid line47d. The plurality of operation valves59ato59dare each capable of setting a pressure of the hydraulic fluid to be delivered according to an operation of the working operation member37.

When the working operation member37is tilted forward, the operation valve59ais operated, and the pilot pressure is output from the operation valve59a. This pilot pressure is applied to a pressure receiver portion of the boom control valve51a, and the hydraulic fluid entering the boom control valve51ais supplied to a rod side chamber of the boom cylinder14, thus the boom10is lowered.

When the working operation member37is tilted backward, the operation valve59bis operated, and a pilot pressure is output from the operation valve59b. This pilot pressure is applied to another pressure receiver portion of the boom control valve51a, and the hydraulic fluid entering the valve51ais supplied to a bottom side chamber of the boom cylinder14, thus the boom10is raised.

That is, the boom control valve51ais capable of controlling a flow rate of the hydraulic fluid flowing to the boom cylinder14according to a pressure of the hydraulic fluid set through an operation of the working operation member37(a pilot pressure set by the operation valve59aand a pilot pressure set by the operation valve59b).

When the working operation member37is tilted rightward, the operation valve59cis operated, and the pilot pressure is applied to a pressure receiver portion of the bucket control valve51b. As the result, the bucket control valve51bis operated in a direction to extend the working tool cylinder15, and the working tool11performs the dumping movement at a speed proportional to a tilting amount of the working operation member37.

When the working operation member37is tilted leftward, the operation valve59dis operated, and the pilot fluid is applied to a pressure receiver portion of the bucket control valve51b. As the result, the bucket control valve51bis operated in a direction to contract the working tool cylinder15, and the working tool11performs the scooping movement at a speed proportional to a tilting amount of the working operation member37.

That is, the bucket control valve51bis capable of controlling a flow rate of the hydraulic fluid flowing in the working tool cylinder15according to a pressure of the hydraulic fluid set through an operation of the working operation member37(a pilot pressure set by the operation valve59cand a pilot pressure set by the operation valve59d). That is, the operation valves59a,59b,59c, and59dchange a pressure of hydraulic fluid according to an operation of the working operation member37, and supply the changed hydraulic fluid to the control valves such as the boom control valve51a, the bucket control valve51b, and the auxiliary control valve51c.

The auxiliary attachments can be operated by a switch56provided in the vicinity of the driver seat7(seeFIG. 8). The switch56is constituted of a tiltable seesaw switch, a slidable slide switch, or a depressable push switch. An operation of the switch56is input to the working controller70. The first solenoid valve56aand the second solenoid valve56b, which are constituted of solenoid valves or the like, have variable openings according to an operation extent of the switch56. As the result, the pilot fluid is supplied to the auxiliary control valve51cconnected to the first solenoid valve56aand the second solenoid valve56b, and an auxiliary actuator of the auxiliary attachment is actuated by hydraulic fluid supplied from the auxiliary control valve51c.

As shown inFIG. 8, operation extents of the operation members (the working operation member37, the traveling operation member54) can be detected by operation detectors77. The operation detectors77are operably connected to the working controller70to be described later. The operation detectors77include a first operation detector77A and a second operation detector77B. The first operation detector77A detects an operation extent of the working operation member37(referred to as a working operation extent). The second operation detector77B detects an operation extent of the traveling operation member54(referred to as a traveling operation extent). The first operation detector77A and the second operation detector77B are position sensors or the like that are configured to detect positions of the operation members.

FIG. 8shows a control block diagram in the working machine1. As shown inFIG. 8, the power controller67is electrically connected to the working controller70. The power controller67includes an inverter67A and an inverter control unit67B.

The inverter67A, for example, includes a plurality of switching elements, and converts a direct current into an alternating current by switching the switching elements or the like. The inverter67A is electrically connected to the motor generator63and the battery66. The inverter control unit67B is constituted of a CPU, electrical and electronic circuits, or the like. When a predetermined signal is output to the inverter control unit67B, the inverter control unit67B operates the motor generator63as either the motor or as the generator. An amount (remaining amount) of energy stored in the battery66can be detected by a charging detection sensor97provided in the battery66.

The working controller70is a device configured to perform various controls of the working device, and is constituted of a CPU, an electrical and/or electronic circuit, or the like. The working controller70performs a control (that is, the hydraulic control) relating to a hydraulic pressure (that is, the hydraulic fluid). In the hydraulic control, the working controller70magnetizes and demagnetizes solenoids of the speed-shifting switching valve44, the first solenoid valve56a, and the second solenoid valve56b, as described above. The working controller70also operates as a controller configured to control the power controller67. The working controller70outputs an assist command to the inverter control unit67B, and the inverter control unit67B operates the motor generator63as the motor. The working controller70outputs a power generation command to the inverter control unit67B, and the inverter control unit67B operates the motor generator63as the generator. That is, under the control by the working controller70, the motor generator63can perform either one of the assisting operation to assist the driving of the engine60and the generating operation to operate as a generator with the power of the engine60to generate electric power. The working controller70sets either one of a powering torque of the motor generator63in the assisting operation and the regenerating torque of the motor generator63in the generating operation, and issues a command about the set torque to the power controller67.

When the motor generator63performs the assisting operation, powers of the engine60and the motor generator63are transmitted to the hydraulic driving device64. When the motor generator63performs the generating operation, a power of the engine60is transmitted to the hydraulic driving device64, and an electric power generated by the motor generator63is charged to the battery66. The motor generator63is driven by the electric power charged in the battery66.

In the above-mentioned embodiment, the working controller70and the electric power controller67are separately configured, but may be integrally configured and are not limited to the configuration of the above-mentioned embodiment.

The working controller70includes a memory unit70a, a powering torque setting unit70b, a regenerating torque setting unit70c, and an operation control unit70d. The memory unit70ais constituted of non-volatile memory or the like. The powering torque setting unit70b, the regenerating torque setting unit70c, and the operation control unit70dare constituted of electrical and/or electronic circuits provided in the working controller70, computer programs or the like stored in a CPU, or the like. The memory unit70a, the powering torque setting unit70b, the regenerating torque setting unit70c, and the operation control unit70dmay be provided in the power controller67.

The memory unit70astores control information used when the motor generator63performs either the assisting operation or the charging operation, for example, stores a control map shown inFIG. 9. The control map shows a relationship between a revolving speed of the engine60(that is, the engine revolving speed) and the selection between the assisting operation and the charging operation (that is, the operation selection), a relationship between the engine revolving speed and a powering torque in the assisting operation, and the relationship between the engine revolving speed and the regenerating torque in the charging operation. In the above-mentioned embodiment, a relationship between the engine revolving speed and the switching of operation, a relationship between the engine revolving speed and the powering torque in assisting operation, and a relationship between the engine revolving speed and the regenerating torque in the charging operation may be shown by control tables, parameters, functions, or the like, which are not limited thereto.

The powering torque setting unit70bsets the powering torque used when the assisting operation is performed. As shown inFIG. 9, the powering torque setting unit70brefers to the control information such as the control map stored in the memory portion70a, and sets the powering torque relative to the engine revolving speed with use of a standard line L1, for example.

The regenerating torque setting unit70csets the regenerating torque used when the generating operation is performed. As shown inFIG. 9, the regenerating torque setting unit70crefers to control information in the same way as the powering torque setting unit70b, and sets the regenerating torque relative to the engine revolving speed with use of the standard line L1, for example. The standard line L1includes a sloping line L1a, in which the torque varies with the engine revolving speed, and a constant line L1b, in which the torque is constant regardless of the engine revolving speed.

The operation control unit70dexecutes the assisting operation by outputting the powering torque to the power controller67when the engine revolving speed is a first revolving speed N1or lower, the powering torque being set by the powering torque setting unit70b, and executes the generating operation by outputting the regenerating torque to the power controller67when the engine revolving speed is a second revolving speed N2higher than the first revolving speed or higher, the regenerating torque being set by the regenerating torque setting unit70c.

As shown inFIG. 10, the working machine1is provided with a cooling device71configured to cool the battery66. The cooling device71is a device configured to be operated by power of the engine60to apply, to the battery66, a cooling air whose temperature is lowered by a refrigerant, thereby cooling the battery66, for example.

The cooling device71is stopped based on an operating state of either one of the hydraulic driving device64, the working device3, and the traveling devices4L and4R. For example, the cooling device71stops when an output of the hydraulic driving device64is a predetermined output or more, when a load generated during operation of the working device3is a predetermined load or more, or when a load generated during operation of the traveling devices4L and4R is a predetermined load or more. In this regard, the cooling device71is activated when the output of the hydraulic driving device64is less than the predetermined output, when the load generated during of the working device3is less than the predetermined load, or when the load generated during operation of the traveling devices4L and4R is less than the predetermined load.

A structure and operation of the cooling device71will be described in detail below.

The cooling device71includes a compressor71a, a condenser71b, a receiver71c, an evaporator71d, and a cooling fan71e. The compressor71aand the condenser71bare connected to each other by a cooling line72such as a pipe, and the receiver71cand the evaporator71dare also connected to each other by another cooling line72. The evaporator71dand the cooling fan71eare housed in a case69that houses the battery66.

The compressor71aincludes a main body71a1, a drive shaft71a2, and a pulley71a3that rotates with the drive shaft71a2. A belt60cwound on a pulley60bthat rotates according to rotation of the output shaft60aof the engine60is wound on the pulley71a3. Thus, a rotational power from the output shaft60aof the engine60is transmitted to the main body71a1through the pulley60b, the belt60c, the pulley71a3, and the drive shaft71a2. The compressor71ais provided with a switch71a4configured to be switched between an ON state and an OFF state. The compressor71ais activated with the electric power supplied when the switch71a4is turned ON under a condition where the power is transmitted to the main body71al. The compressor71ais stopped with the supply of electric power stopped when the switch71a4is turned off under a condition the power is transmitted to the main body71a1. That is, the switch71a4is an electric power switch.

When the compressor71ais activated, refrigerant in the cooling line72is compressed and output to the condenser71b. The compressor71a, when activated, compresses the refrigerant and delivers the compressed refrigerant to the condenser71bthrough the cooling line72.

The condenser71bis provided with a cooling fan to lower a temperature of the refrigerant.

The refrigerant that has passed through the condenser71bflows to the evaporator71dthrough the receiver71c, and refrigerant that has passed through inside of the evaporator71dreturns to the compressor71a.

As shown inFIG. 10, a cooling line73may be branched from a section72aof the cooling line72between the receiver71cand the evaporator71d, and may be connected to an air conditioner74provided in the cabin5. On-off valves75aand75bconstituted of solenoid valves or the like are connected to the section72aof the cooling line72and the cooling line73. The on-off valves75aand75bcan be switched by the working controller70. The on-off valve75bis closed when the on-off valve75ais opened. The on-off valve75bis opened when the on-off valve75ais closed. In this manner, the refrigerant in the cooling lines72and73is allowed to selectively flow either to the side for cooling the battery66(to the evaporator71d) or to the air conditioner74.

As shown inFIG. 8, the working machine1is provided with a load detection unit (load detector)76. The load detector76detects an operating state of at least one of the hydraulic driving device64, the working device3, and the traveling devices4L and4R, that is, detects the load. For example, the load detector76is a pressure detector sensor configured to detect a pressure of hydraulic fluid. The load detector76is operably connected to the working controller70.

The load detector (that is, the pressure detection sensor)76is provided on each of the speed-shifting fluid lines57hand57i, for example. The load detectors76provided on the respective speed-shifting fluid lines57hand57ican detect respective pressures after operations of the traveling pumps52L and52R (referred to as pump-output pressures), and the pump-output pressures can be considered as loads on the traveling pumps52L and52R (that is, output loads) or as loads on the traveling devices4L and4R (that is, output loads).

The load detector (that is, the pressure detection sensor)76may be provided on a fluid line connecting the hydraulic cylinder of the working device3to the control valve51(that is, the boom control valve51a, the bucket control valve51b). In this case, due to the load detector (that is, the pressure detection sensor)76, the pressures of the hydraulic cylinders (that is, the boom cylinder14, the working tool cylinder15) of the working device3during the working (referred to as the working pressure) can be considered as a load on the working device3(referred to as the output load).

As shown inFIG. 11A, the working controller70judges whether the cooling device71(that is, the compressor71a) is operated or not (S1). When the cooling device71is operated (S1, Yes), the working controller70monitors the output load on any of the traveling pumps52L and52R, the traveling devices4L and4R, and the hydraulic cylinders of the working device3(S2).

When the output load is equal to or larger than a predetermined judgment load (S3, Yes), the working controller70stops the cooling device71(that is, the compressor71a) by switching the switch71a4from ON to OFF (S4). On the other hand, when the output load is less than the judgment load (S3, No), the working controller70keeps (maintains) the switch71a4in the ON state. The judgment load is a value to be used to judge whether or not an excessive load is applied to the working machine1in either the working or the traveling.

In the above-mentioned embodiment, it is judged whether or not the output load on any of the traveling pumps52L and52R, the traveling devices4L and4R, and the hydraulic cylinders of the working device3is the judgment load or more. Additionally, the cooling system71may be stopped when a combined total load on at least two output loads is the judgment load or more.

In addition, the cooling device71may be stopped when an operation extent of the operation member (that is, the working operation member37or the traveling operation member54) is a predetermined extent or more.

As shown inFIG. 11B, when the cooling device71(that is, the compressor71a) is operated (S1, Yes), the working controller70monitors either the working operation extent of the working operation member37detected by the first operation detector77A or the traveling operation extent of the traveling operation member54detected by the second operation detector77B (S10). When either the working operation extent or the traveling operation extent is the predetermined judgment operation extent or more (S11, Yes), the working controller70switches the switch71a4from the ON state to the OFF state (S12). On the other hand, when each of the working operation extent and the traveling operation extent is less than the judgment operation extent (S11, No), the working controller70keeps (maintains) the switch71a4in the ON state. The judgment operation extent is a value to be used to judge whether or not the working device3or the traveling devices4L and4R should be operated quickly.

In the above-described embodiment, it is judged whether or not either the working operation extent or the traveling operation extent is the judgment operation extent or more. Additionally, the cooling device71may be stopped when the total operation extent which is the sum of at least two extents, the working operation extent and the traveling operation extent, is the judgment load or more.

It may also be judged, based on a temperature of the battery66, whether or not to stop the cooling device71. The temperature of the battery66is detected by the temperature detector78. The temperature detector78is provided inside the case69, and detects the temperature of the battery66. The temperature detector78is connected to the working controller70.

As shown inFIG. 11C, when the cooling device71is operated (S1, Yes), the working controller70judges whether or not a temperature (referred to as a battery temperature) detected by the temperature detector78is the cooling judgment value or higher (S20). The cooling judgment value is a value used to determine whether or not the battery66needs to be cooled. The cooling judgment value is set as 50° C. or higher, for example. The cooling judgment value is not limited thereto.

When the battery temperature is the cooling judgment value or higher (S20, No), the working controller70keeps (maintains) the switch71a4in the ON state. On the other hand, when the battery temperature is less than the cooling judgment value (S20, Yes), the working controller70monitors the output load (S2) similar to the process inFIG. 11A, and when the output load is the judgment load or more (S3, Yes), the cooling device71is stopped (S4). On the other hand, when the output load is less than the judgment load (S3, No), the working controller70keeps (maintains) the switch71a4in the ON state.

In the present embodiment, the cooling device71(that is, the compressor71a) is stopped by switching the switch71a4between the ON state and the OFF state. Alternatively, the working controller70may engage or disengage an electromagnetic clutch interposed between the driving shaft71a2of the compressor71aand the output shaft60ato stop the cooling device71(that is, the compressor71a).

The working machine1includes the machine body2, the engine60, the motor generator63, the battery66, the cooling device71, the hydraulic driving device64, the working device3, and the traveling devices4L and4R, and the cooling device71is stopped based on the operating state of any one of the hydraulic driving device64, the working device3, and the traveling devices4L and4R. According to this configuration, a driving power of the engine60can be secured by stopping the cooling device71, and a storing capacity of the battery66can be secured without lowering the powering torque or the like on the motor generator63.

The working machine1includes the load detection unit (load detector)76configured to detect a load on any of the hydraulic driving device64, the working device3, and the traveling devices4L and4R—The cooling device71is stopped when the load detected by the load detection unit (that is, the load detector)76is the predetermined load or more. Accordingly, when an output load is applied on any of the hydraulic driving device64, the working device3, and the traveling devices4L and4R, the cooling device71is stopped to secure a driving force of the engine60.

The working device3includes the operation member (the working operation member37or the traveling operation member54) for operating either the working device3or the traveling devices4L and4R. The cooling device71is stopped when the operation extent of the operation member (the working operation member37or the traveling operation member54) is the predetermined extent or more. According to this configuration, the cooling device71can be efficiently stopped when the operation extent of the operation member is the predetermined extent or more and the power outputting is required. That is, an operation of the cooling device71can be maintained or stopped in synchronization with the operation extent of the operation member.

The working machine1includes the temperature detector78configured to detect the temperature of the battery66. The cooling device71is not stopped when the temperature detected by the temperature detector78is a predetermined temperature or more. According to this configuration, when the temperature of the battery66is high, the cooling by the cooling device71can be given priority.

The cooling device71includes the evaporator71dthrough which the refrigerant for cooling the battery66flows, and the compressor71aconfigured to compress the refrigerant that has flown through the evaporator71d. The compressor71ais selectively stopped based on its operating state. According to this configuration, the cooling device71can be entirely and easily stopped by stopping compression of the refrigerant by the compressor71a.

As shown inFIGS. 8 and 12, the working machine1includes an inertial measurement unit (IMU)90configured to measure an inertial force of the machine body2.

The inertial measurement unit90is attached, for example, below the driver seat7, inside the cabin5, on the top plate (that is, an outer roof) of the cabin5, or on the bottom frame portion23. The position of the inertial measurement unit90is not limited to of the above-mentioned positions in the embodiment. The inertial measurement unit90includes a gyro sensor that detects an angular velocity in three axes (that is, the X, Y, and Z axes) and an angular accelerometer that detects an angular acceleration. In other words, the inertial measurement unit90is a device that includes two acceleration sensors, i.e., the gyro sensor and the angular accelerometer. The inertial measurement unit90to be provided in the working machine1is not limited to that having the two acceleration sensors, and may be provided with only a single gyro sensor.

The inertial measurement unit90is capable of detecting a roll angle, a pitch angle, a yaw angle, and the like of the machine body2. The inertial measurement unit90is electrically connected to the working controller70.

The working controller70estimates, based on the inertial force of the machine body2measured by the inertial measurement unit90, what kind of traveling state the machine body2is in, and selectively sets either the assisting operation or the generating operation based on the estimated traveling state.

The setting of the assisting operation and the power generation command based on the inertial force detected by the inertial measurement unit90will be described below.

As shown inFIG. 12, the working controller70refers to a fore-and-aft directional acceleration (referred to as a first acceleration) A1of the machine body2, a left-and-right (or width) directional acceleration (referred to as a second acceleration) A2of the machine body2, and a yaw rate A3of the working machine1(that is, the machine body2), which are measured by the inertial measurement unit90.

As shown inFIG. 13, when the first acceleration A1is not less than a threshold thereof, the working controller70estimates that the machine body2is in a straight traveling state where the machine body2is traveling straight. When the first acceleration A1is less than the threshold, the working controller70estimates that the machine body2is in a non-straight traveling state defined as any traveling state other than the straight traveling state.

The working controller70estimates, based on the second acceleration A2and the yaw rate A3, whether the machine body2is in a turning state where the machine body2is turning or not. For example, the working controller70estimates that the machine body2is turning in a way referred to as first turning when the second acceleration A2is the threshold thereof or larger and the yaw rate A3is a threshold thereof or larger. The working controller70also estimates that the machine body2is turning in a way referred to as second turning when the second acceleration A2is less than the threshold thereof and the yaw rate A3is the threshold thereof or larger. On the other hand, when the second acceleration A2is less than the threshold thereof and the yaw rate A3is also less than the threshold thereof, the working controller70estimates that the machine body2is in a state other than the turning state. That is, the working controller70distinguishingly estimates, based on the second acceleration A2and the yaw rate A3, either one of the two kinds of turnings, e.g., the ultra-pivotal turn and the pivotal turn, as well as whether the machine body2is in a state other than the turning.

As described above, the working controller70is configured to estimate, based on an inertial force, what kind of traveling state (such as the straight traveling, the first turning, the second turning, or a state other than the turning) the machine body2is in. The working controller70makes various settings in the assisting operation or the power generation command in correspondence to the traveling state (the straight traveling, the first turning, the second turning, or the state other than the turning) in which the machine body2is.

Either the powering torque setting unit70bor the regenerating torque setting unit70cchanges the setting of either the powering torque or the regenerating torque based on the inertial force of the machine body2. For example, as shown inFIG. 9, when, in consideration of the traveling state of the machine body2estimated based on the inertial force of the machine body2, the powering torque setting unit70bor the regenerating torque setting unit70cneeds to increase the torque at a given engine speed in the assisting operation or charging operation to a torque larger than that on the standard line L1at the same engine speed, the torque on the slope line L1aof the standard line L1is changed to a torque on a correction line L2indicating variation of given by shifting the slope line L1aof the standard line L1to the higher side of an engine revolving speed when In addition, when, in consideration of the traveling state of the machine body2estimated based on an inertial force of the machine body2, the torque per unit engine revolution needs to be larger than that on the standard line L1, the powering torque setting unit70bchanges the torque to a torque on a correction line L3. When instantaneously increasing a torque is needed, the powering torque setting unit70bchanges the torque to a torque on a correction line L4.

For example, when the traveling state is estimated as the straight traveling, each of the powering torque setting unit70band the regenerating torque setting unit70csets a torque based on the standard line L1. When the traveling state is estimated as the turning (the ultra-pivotal turn, the pivotal turn), the powering torque setting unit70bsets a torque based on the correction line L3. In particular, when an instantaneous torque is required, the powering torque setting unit70bsets a torque based on the correction line L4. When the traveling state is estimated as a state other than the turning, each of the powering torque setting unit70band the regenerating torque setting unit70csets a torque based on the correction line L2. The above-mentioned examples are just examples, and are not limited.

The correction lines L2to L4may be prepared in advance as control information in the memory unit70a, may be calculated by the reduction amount ΔE1of the engine revolving speed, or may be obtained by a formula (function) so that their slopes become larger than that of the standard line L1in correspondence to a difference between the first revolving speed N1and the second revolving speed N2. In the correction lines L2to L4, the rate (slope) of increasing of the torque may be set according to a magnitude of the inertial force.

Alternatively, as shown inFIG. 14, the working controller70may change the first revolving speed N1and the second revolving speed N2indicated by the standard line L1based on a magnitude of the inertial force of the machine body2. As shown inFIG. 14, while an inclination of the slope line L1aof the standard line L1is not changed, the larger the inertial force becomes, the more the first and second revolving speeds N1and N2are shifted in the direction lowering the revolving speed. The only requirement is that a torque or the like is set according to the inertial force detected by the inertial measurement unit90, and the setting is not limited to the above-mentioned embodiment.

The working machine1includes the acceleration sensor configured to measure the acceleration of the machine body2, and the controller (that is, the working controller70, the power controller67) configured to selectively set either the assisting operation or the generating operation based on the acceleration of the machine body2measured by the acceleration sensor. According to this configuration, even when the working machine1shows various behaviors in the working, the inertial measurement unit90is capable of detecting the behaviors in the working, so that the settings such as the torque can be easily made based on the operations of the working machine1.

The controller (that is, the working controller70, the power controller67) estimates what kind of traveling state the machine body2is in based on the acceleration of the machine body2measured by the acceleration sensor, and selectively sets either the assisting operation or the generating operation based on the traveling state. According to this configuration, the inertial measurement unit90is adaptable for estimating the various traveling states, and for quickly judging, based on the estimated traveling state, whether to perform the assisting operation or the generating operation.

The controller d (that is, the working controller70, the power controller67) estimates that the machine body2is in the straight traveling state where the machine body2is traveling straight when the fore-and-aft directional acceleration of the machine body2is not less than the threshold. The controller estimates that the machine body2is in the non-straight traveling state defined as any traveling state other than the straight traveling state when the fore-and-aft directional acceleration is less than the threshold. The controller selectively sets either one of the assisting operation and the generating operation based on whether the traveling state is estimated as the straight traveling state or the non-straight traveling state. According to this configuration, the selective setting of either the assisting operation or the generating operation can be performed immediately after the estimation of whether the machine body2is traveling straight or not.

The controller (that is, the working controller70, the power controller67) estimates, based on the width directional acceleration of the machine body2and on the yaw rate of the machine body2, whether the machine body2is in the turning state where the machine body2is turning or not. The controller selectively sets either one of the assisting operation and the generating operation based on whether or not the traveling state is estimated as the turning state. According to this configuration, the selective setting of either the assisting operation or the generating operation can be performed immediately after the estimation of whether the machine body2is turning or not.

Either the powering torque setting unit70bor the regenerating torque setting unit70cchanges the setting of either the powering torque or the regenerating torque based on the acceleration of the machine body2. According to this configuration, the powering torque and the regenerating torques can be appropriately changed in correspondence to increase, reduction, or the like of the acceleration.

The controller (that is, the working controller70, the power controller67) changes either the first revolving speed N1or the second revolving speed N2based on the acceleration of the machine body2. According to this configuration, based on the acceleration of the working machine1in operation, whether to intensify the assisting operation or the generating operation is easily determined.

The working controller70may stop or limit the assisting operation when an outputting condition relating to outputting from the traveling devices4L and4R deviates from that corresponding to an inputting condition relating to inputting to the traveling devices4L and4R. For example, the assisting operation is stopped or limited when it is hard for an operator operating the traveling operation member54to expect a profit of the assisting operation, such as when the traveling devices4L and4R run idle, the rotations of the traveling devices4L and4R stop, or the speed (vehicle speed) of the machine body2is too slow or too fast.

The following explains an operation when the outputting condition of the traveling devices4L and4R deviates from that corresponding to the inputting condition of the traveling devices4L and4R. In the following description, the explanation is made with the working controller70as an example, but the power controller67instead of the working controller70may perform the same operation of the working controller70.

As shown inFIG. 8, the working machine1includes a rotation detector85configured to detect the rotation speeds of the traveling devices4L and4R. The rotation detector85includes sensors configured to detect respectively the rotation speeds M1and M2of the output shafts35L and35R of the traveling motors36L and36R.

When the operation extent of the traveling operation member54is defined as the inputting state and the rotation speeds M1and M2detected by the rotation detector85are defined as the outputting state, the working controller70stops or limits the assisting operation when the rotation speeds M1and M2are lower than that corresponding to the operation extent of the traveling operation member54.

For example, as shown inFIG. 15, during operation of the traveling operation member54for forward traveling, when the rotation speeds (referred to as traveling rotation speeds) M1and M2detected by the rotation detector85gradually increase as shown in a line L6, the working controller70continues the assisting operation. On the other hand, the working controller70stops the assisting operation when the traveling rotation speeds M1and M2are almost zero as shown in a line L7aor when the rotations of the traveling devices4L and4R are stopped.

FIG. 16Ashows a processing (that is, the control) to be executed when the traveling rotation speeds M1and M2are lower than that corresponding to the operation extent of the traveling operation member54. As shown inFIG. 16A, when the assisting operation is being performed (S30, Yes), the working controller70refers to the traveling rotation speeds M1and M2detected by the rotation detector85(S31). In addition, the working controller70refers to either the operation extent of the traveling operation member54or the set rotation speed set based on the operation extent (S32). The working controller70judges whether both the traveling rotation speeds M1and M2are lower than that corresponding to the operation extent of the traveling operation member54by at least a predetermined value (S33). For example, as shown inFIG. 15, when rotation differences ΔM1and ΔM2, which are differences between the set rotation speeds corresponding to the predetermined operation extent (the rotation speed set based on the line L6) and the actual traveling rotation speeds M1and M2detected by the rotation detector85, are the predetermined value or more, and both the rotations of the traveling devices4L and4R are lower than the set rotation speeds by the predetermined value or more (S33, Yes), for example, when the traveling devices4L and4R stop or the traveling devices4L and4R run idle under low rotation speeds of the traveling rotation speeds M1and M2, the assisting operation is stopped or limited (S34). When the assisting operation is limited, the torque set by the powering torque setting unit70bbased on the standard line L1is reduced. For example, an amount of torque reduction may be set based on the magnitude of the rotation differences ΔM1and ΔM2(for example, the amount of torque reduction=the rotation differences ΔM1and ΔM2×a constant).

In addition, the working controller70stops the assisting operation when both of the traveling rotation speeds M1and M2are higher than that corresponding to an operation extent of the traveling operation member54.

As shown inFIG. 15, when both of the traveling rotation speeds M1and M2detected by the rotation detector85are higher than those on the line L7b, the working controller70stops or limits the assisting operation.

FIG. 16Bshows a processing (that is, the control) to be executed in a case where the traveling rotation speeds M1and M2are higher than those corresponding to the operation extent of the traveling operation member54. Steps S31to S32inFIG. 16Bare the same as those inFIG. 16A. As shown inFIG. 16B, the working controller70judges whether each of the traveling rotation speeds M1and M2is higher than that corresponding to an operation extent of the traveling operation member54by at least a predetermined value (S35). For example, as shown inFIG. 15, when each of the rotation differences ΔM1and M2between the set rotation speeds corresponding to the predetermined operation extent and the traveling rotation speeds M1and M2detected by the rotation detector85is not lower than the predetermined value, and the traveling rotation speeds M1and M2are higher than those corresponding to the operation extent by at least the predetermined value (S35, Yes), for example, when the traveling rotation speeds M1and M2are high and the traveling devices4L and4R are accelerating during descending a slope, the assisting operation is stopped or limited (S36). The method for limiting the assisting operation is the same as that described above.

In the above-described embodiment, the assisting operation is stopped or limited when each of the traveling rotation speeds M1and M2of the traveling devices4L and4R is lower or higher than that corresponding to an operation extent of the traveling operation member54. Alternatively, the assisting operation may be stopped or limited based on a speed (that is, the vehicle speed) of the machine body.

As shown inFIG. 8, the working machine1includes a vehicle-speed detector86configured to detect the vehicle speed of the machine body2. The vehicle-speed detector86is a device configured to respectively convert the traveling rotation speeds M1and M2of the output shafts35L and35R of the traveling motors36L and36R into the traveling vehicle speeds V1and V2. Although the vehicle-speed detector86is configured to convert the traveling rotation speeds M1and M2into the traveling vehicle speeds V1and V2, rotations of any portions driving the traveling devices4L and4R of the working machine1, such as rotations of axles, may be converted into the traveling vehicle speeds V1and V2. What is converted to the traveling vehicle speed is not limited thereto.

When the operation extent of the traveling operation member54is defined as the inputting state and the traveling vehicle speeds V1and V2detected by the vehicle-speed detector86are defined as the outputting state, the working controller70stops or limits the assisting operation when the traveling vehicle speeds V1and V2are lower than that corresponding to the operation extent of the traveling operation member54.

For example, as shown inFIG. 17, when the traveling vehicle speeds V1and V2are gradually increased by operating the traveling operation member54is operated in the forward traveling operation direction, the working controller70continues the assisting operation. On the other hand, when the traveling vehicle speeds V1and V2scarcely rise (increase) as shown by a line L8a, the working controller70stops the assisting operation.

As shown inFIG. 18A, when the assisting operation is being performed (S40, Yes), the working controller70refers to the traveling vehicle speeds V1and V2detected by the vehicle-speed detector86(S41). In addition, the working controller70refers to either an operation extent of the traveling operation member54or the vehicle speed set based on the operation extent (S42). The working controller70judges whether both of the traveling vehicle speed V1and V2are each lower than that corresponding to the operation extent of the traveling operation member54by at least a predetermined value (S43). For example, as shown inFIG. 17, when vehicle speed differences ΔV1and ΔV2between the set vehicle speed set based on the operation extent according to the line L6and the actual traveling vehicle speeds V1and V2detected by the vehicle-speed detector86is a predetermined value or more and both of the traveling vehicle speeds V1and V2are each lower than that corresponding to the operation extent by at least the predetermined value (S43, Yes), for example, when the traveling devices4L and4R are stopped or the traveling devices4L and4R run idle under the low traveling vehicle speeds V1and V2, the assisting operation is stopped or limited (S44). When the assisting operation is limited, the torque set by the powering torque setting unit70bbased on the standard line L1is reduced.

For example, an amount of torque reduction may be set based on a magnitude of the vehicle speed differences ΔV1and ΔV2(for example, the amount of torque reduction=the vehicle speed differences ΔV1and ΔV2×a constant).

In addition, the working controller70stops the assisting operation when both of the traveling vehicle speeds V1and V2are each higher than that corresponding to an operation extent of the traveling operation member54.

As shown inFIG. 17, when the traveling vehicle speeds V1and V2given by operating the traveling operation member54in the forward-traveling operation direction are high as shown by the line L8b, the working controller70stops or limits the assisting operation.

FIG. 18Bshows an operation performed when the traveling vehicle speeds V1and V2are each higher than that corresponding to an operation extent of the traveling operation member54. Steps S41to S42inFIG. 18Bare the same as those inFIG. 18A. As shown inFIG. 18B, the working controller70judges whether the traveling vehicle speeds V1and V2are each higher than that corresponding to the operation extent of the traveling operation member54by at least a predetermined value (S45). For example, as shown inFIG. 17, when the rotation differences ΔM1and ΔM2between the set vehicle speeds corresponding to a predetermined operation extent and the actual traveling vehicle speeds V1and V2detected by the vehicle-speed detector86are each equal to or larger than the predetermined value and the traveling vehicle speeds V1and V2are each higher than that corresponding to the operation extent by at least the predetermined value (S45, Yes), for example, when the traveling vehicle speeds V1and V2are high and the traveling devices4L and4R are accelerating during descending a slope, the assisting operation is stopped or limited (S46). The method for limiting the assisting operation is the same as the method described above.

The powering torque setting unit70bincreases the powering torque when a load on the engine60is increasing, and reduces the powering torque when the load on the engine60is reducing. In other words, the powering torque setting unit70bincreases the powering torque when the engine revolving speed detected by the detection sensor91is reducing, and reduces the powering torque when the engine revolving speed is increasing.

In particular, as shown inFIG. 21, when the engine revolving speed E1detected by the detection sensor91gradually reduces after a time point P50under the state where the working controller70(that is, the operation control unit70d) is performing the assisting operation, the powering torque setting unit70bgradually increases the powering torque from the time point P50as the engine revolving speed E1reduces. When the engine revolving speed E1begins to gradually increase after a time point P51, the powering torque setting unit70bgradually reduces the powering torque from the time point P51in accordance with the gradual reduction in the engine revolving speed E1. In other words, under the state where the assisting operation is being performed, the powering torque setting unit70bincreases the powering torque in a reducing section T50where the engine revolving speed E1is reducing, and the powering torque setting unit70breduces the powering torque in an increasing section T51where the engine revolving speed E1is increasing.

When the motor generator63is performing the assisting operation and the outputting condition relating to outputting from the traveling devices4L and4R deviates from that corresponding to the inputting condition relating to inputting to the traveling devices4L and4R, the controller (that is, the working controller70or the power controller67) stops or limits the assisting operation. According to this configuration, since the assisting operation by the motor generator63is not effective when the outputting condition of the traveling devices4L and4R deviates from that corresponding to the inputting condition of the traveling devices4L and4R, the unnecessary assisting operation is not performed, so that the assisting operation is performed only when the assistance is needed, thereby efficiently operating the motor generator.

The controller (that is, the working controller70or the power controller67) stops or limits the assisting operation when the rotation speeds of the traveling rotation speeds M1and M2are each lower than that corresponding to the operation extent of the traveling operation member54. According to this configuration, the assisting operation can be prevented from being wastefully performed. For example, an unnecessary assisting operation can be prevented when the machine body2or the like cannot travel forward or the traveling devices4L and4R slip wheels because the machine body2runs into earth or sand to fill its working tool with the earth or sand (in the scooping operation) to be conveyed.

The controller (that is, the working controller70or the power controller67) stops or limits the assisting operation when the rotation speeds of the traveling rotation speeds M1and M2are each higher than that corresponding to the operation extent of the traveling operation member54. According to this configuration, an unnecessary assist operation can be prevented when the vehicle is traveling downhill at the traveling rotation speeds M1and M2each of which is higher than that corresponding to the operation extent of the traveling operation member54.

The controller (that is, the working controller70or the power controller67) stops or limits the assisting operation when the traveling vehicle speeds V1and V2are each lower than that corresponding to an operation extent of the traveling operation member54. According to this configuration, an unnecessary assisting operation can be prevented in a case where the traveling devices4L and4R slip wheels, for example, in the scooping operation.

The controller (that is, the working controller70, the power controller67) stops or limits the assisting operation when the traveling vehicle speeds V1and V2are higher than that corresponding to an operation extent of the traveling operation member54. According to this configuration, the unnecessary assisting operation can be prevented in a case where the vehicle is traveling downhill.

The powering torque setting unit70breduces the powering torque when the outputting condition relating to outputting from the traveling devices4L and4R deviates from that corresponding to the inputting condition relating to inputting to the traveling devices4L and4R. Accordingly, consumption of electric power in the battery66can be suppressed in the assisting operation.

The working controller70may limit an output of the hydraulic driving device64and the assisting operation by, for example, setting an opening aperture of the anti-stall control valve48when the reduction amount (that is, a dropping amount) ΔE1of the engine revolving speed is a predetermined value or more. For example, the working controller70limits outputs of the traveling pumps52L and52R to limit the powering torque in the assisting operation.

The following description explains an operation in a case where the reduction amount ΔE1of the engine revolving speed is a predetermined value or more. In the following explanation, the working controller70is used as an example, but the power controller67instead of the working controller70may perform the same operation of the working controller70.

As shown inFIG. 19, when the assisting operation is being performed (S50, Yes), the working controller70monitors the reduction amount ΔE1of the engine revolving speed (S51). When the reduction amount ΔE1is the anti-stall judgment value or more (S52, Yes), an opening aperture of the anti-stall control valve48is set based on the setting line L52(S53). In addition, the working controller70judges whether or not a moving average value Dave of the reduction amount ΔE1is a judgment value W1or more (S54). As shown inFIG. 20, when the moving average value Dave of the reduction amount ΔE1is the predetermined judgment value W1or more (S54, Yes), the working controller70reduces the torque to a new torque smaller than the powering torque set, based on the standard line L1, by the powering torque setting unit70b(S55).

When the moving average value Dave of the reduction amount ΔE1is the judgment value W1or more for a predetermined period of time T10or more, the powering torque setting unit70bmay reduce the torque from the powering torque set, based on the standard line L1, by the powering torque setting unit70b.

For example, it is assumed that the powering torque provided when the moving average value Dave of the reduction amount ΔE1is less than the judgment value W1is set to a torque “J1.” On the assumption, the powering torque setting unit70bof the working controller70may reduce the powering torque J1to a new powering torque J2less than the powering torque J1(J2<J1) when the moving average value Dave of the reduction amount ΔE1is the judgment value W1or more. In other words, the powering torque setting unit70breduces the powering torque to a new torque smaller than the powering torque corresponding to the standard line L1during a period T1where the moving average value Dave of the reduction amount ΔE1is the judgment value W1or more. For example, as shown inFIG. 9, the powering torque setting unit70bsets the powering torque as the powering torque J2based on a line L15rather than the powering torque J1based on the constant line L1b.

The slope of the line L15, that is, the reduction amount of the powering torque may be set to a predetermined value, or the reduction amount may be set based on the dropping amount ΔE, that is, the moving average value Dave.

In addition, when the moving average value Dave is the judgment value W1or more, the working controller70may make the primary traveling pressure smaller than the pressure on a setting line L52at a predetermined engine revolving speed. That is, the difference (referred to as a reducing pressure) between the pressure set based on the setting line L52and the reference pilot pressure set based on the setting line L51may be increased. That is, as shown inFIG. 7, when the moving average value Dave is the judgment value W1or more, the working controller70increases a difference between the setting line L52and the setting line L51by changing the setting line L52to a setting line L52ahaving a slope different from that of the setting line L52or by moving the setting line L52to a setting line L52bparallel to the setting line L52.

In the above-mentioned embodiment, the powering torque is reduced based on the moving average value Dave of the reduction amount ΔE1; however alternatively, the transition (an attenuating rate) of the reduction amount ΔE1of the engine revolving speed may be obtained through a low-pass filter, and thus the powering torque may be reduced when the attenuating rate is the judgment value W1or more. Also in this case, the method for reducing the powering torque is the same as the method described above.

In the above-mentioned embodiment, the opening aperture of the anti-stall control valve48is adjusted when the reduction amount ΔE1of the engine revolving speed becomes a predetermined value more; however, in the working machine1that is not provided with the anti-stall control valve48, the traveling motors36L and36R may be decelerated from the second speed to the first speed when the reduction amount ΔE1is the anti-stall judgment value or more (S52, Yes).

The controller (that is, the working controller70or the power controller67) limits the output of the hydraulic driving device64and limits the assisting operation when the reduction amount ΔE1of the engine revolving speed is a predetermined value or more. Accordingly, not only the output of the hydraulic driving device64is limited based on the state of the engine60, but also the assisting operation is limited. For example, in an overload state where the reduction amount ΔE1of the engine revolving speed is a predetermined value or more, the overload on the engine60can be reduced by limiting the output of the hydraulic driving device64, while the reduction in the storing capacity of the battery66can be suppressed by limiting the assisting operation.

The controller (that is, the working controller70or the power controller67) limits the outputs of the traveling pumps52L and52R and limits the powering torque in the assisting operation.

According to this configuration, the reduction of the storing capacity of the battery66can be suppressed by limiting the powering torque under a state where the outputs of the traveling pumps52L and52R is reduced.

The controller (that is, the working controller70or the power controller67) limits the primary traveling pressure output from the traveling operation valve55when the reduction amount ΔE1of the engine revolving speed is a predetermined value or more. The controller (that is, the working controller70or the electric power controller67) makes the primary traveling pressure (referred to as the primary pilot pressure) of the anti-stall control valve48smaller than the predetermined reference pilot pressure when the reduction amount ΔE1of the engine revolving speed is the predetermined value or more. According to this configuration, the stalling of the engine60can be efficiently prevented by limiting the primary traveling pressure output from the traveling operation valve55.

The controller (that is, the working controller70or the power controller67) sets the reducing pressure, which is the difference between the primary traveling pressure and the reference pilot pressure, based on the reduction amount ΔE1of the engine revolving speed. According to this configuration, the load on the engine60can be reduced.

The powering torque setting unit70breduces the powering torque based on the reduction amount ΔE1of the engine revolving speed. According to this configuration, the powering torque can be adjusted according to the load on the engine60.

In the above-described embodiment, the operation valves55and59are configured to change the pilot pressure when the working operation member37and the traveling operation member57are operated; however, the operation members may be electrically operable members. That is, the operating devices43and53may be devices configured to operate the hydraulic driving device64, and the control valves51and48with electric signals.