Patent Description:
With regard to a working machine such as a compact track loader, Patent document <NUM> is known as a hybrid-type working machine which includes an engine and a motor/generator. The working machine of Patent document <NUM> is such that: excavation work, during which the output of a hydraulic pump is expected to be high, is performed in a work mode which is a first mode; non-excavation work, during which the output of the hydraulic pump is somewhat lower than in excavation state, is performed in a work mode which is a second mode; and determination regarding an assisting action by the motor/generator is performed according to whether the work mode is the first mode or the second mode.

In Patent document <NUM>, determination regarding the assisting action is performed according to work done by the working machine. However, even if the work done by the working machine is the same, the work may require different forces (working forces), and therefore, in reality, it is not possible to perform an assisting action and/or the like sufficiently corresponding to the work.

In Patent document <NUM>, determination regarding the assisting action is performed according to work done by the working machine. However, an assisting action is sometimes performed even through the engine is not working at full power.

In Patent document <NUM>, determination regarding the assisting action is performed according to work done by the working machine. However, even if the work done by the working machine is the same, the work may require different forces (working forces), and therefore, in reality, it is not possible to perform an assisting action and/or the like sufficiently corresponding to the work. Patent document <NUM> describes a hybrid operating machine for a construction machine. Patent document <NUM> describes a hybrid work machine with the features of the preamble of present claim <NUM>.

The present invention was made in order to solve such issues of the conventional technique, and an object thereof is to provide a working machine which makes it possible to flexibly change the output depending on the work. Another object is to provide a working machine which makes it possible, when engine needs assistance, to effectively perform the assistance.

A working machine according to the present invention comprises: a machine body; an engine provided on the machine body: a motor/generator to perform an assisting action in which the motor/generator functions as a motor to assist the engine in driving and an electricity generating action in which the motor/generator functions as a generator to generate electricity using power from the engine; a working device configured to function using power from the engine and the motor/generator; a work operation member for operation of the working device; an action control unit to cause the assisting action to be performed when a rotation speed of the engine is equal to or less than a first rotation speed and cause the electricity generating action to be performed when the rotation speed of the engine is equal to or greater than a second rotation speed, the second rotation speed being greater than the first rotation speed; and a switching changing unit to change the first rotation speed or the second rotation speed according to an operation amount of the work operation member.

The working device includes a boom swingably provided on the machine body, a boom cylinder to swing the boom, a working tool swingably provided on the boom, and a working tool cylinder to swing the working tool ; and the switching changing unit makes a change of the first rotation speed or the second rotation speed according to the operation amount of the work operation member operated to activate the working tool cylinder.

When the work operation member is operated to activate the boom cylinder and the working tool cylinder, the switching changing unit does not make the change of the first rotation speed or the second rotation speed according to the operation amount.

When the work operation member is operated to activate the boom cylinder to raise the boom, the switching changing unit does not make the change of the first rotation speed or the second rotation speed according to the operation amount.

A working machine that is not part of the claimed invention comprises: the machine body; an engine provided on the machine body: a motor/generator to perform an assisting action in which the motor/generator functions as a motor to assist the engine in driving and an electricity generating action in which the motor/generator functions as a generator to generate electricity using power from the engine; a hydraulic drive device configured to receive power from the engine and the motor/generator; an operation member for operation of the hydraulic drive device; and a control device to set, according to a change in rotation speed of the engine after operation of the operation member, a point in time at which the assisting action is performed.

The control device causes the assisting action to be performed after the rotation speed of the engine has started decreasing after having increased.

The working machine further comprises: an operation valve to determine a pilot pressure according to the operation of the operation member, wherein an output of the hydraulic drive device changes with the pilot pressure determined by the operation valve.

The working machine further comprises: a pair of traveling devices provided on the machine body; and a pair of travel motors to drive the pair of traveling devices, wherein the hydraulic drive device includes a pair of travel pumps to drive the pair of travel motors.

The control device causes the assisting action to be started when a speed at which the machine body is turned by the pair of traveling devices has increased and the rotation speed of the engine has decreased after having increased.

A working machine that is not part of the claimed invention comprises: the machine body; an engine provided on the machine body; a motor/generator to perform an assisting action in which the motor/generator functions as a motor to assist the engine in driving and an electricity generating action in which the motor/generator functions as a generator to generate electricity using power from the engine; a pair of traveling devices provided on the machine body; a travel operation member for operation of the pair of traveling devices; an action control unit to cause the assisting action to be performed when a rotation speed of the engine is equal to or less than a first rotation speed and cause the electricity generating action to be performed when the rotation speed of the engine is equal to or greater than a second rotation speed, the second rotation speed being greater than the first rotation speed; and a switching changing unit to change the first rotation speed or the second rotation speed according to an operation amount of the travel operation member.

The machine body is configured to make a first turn in which one of the pair of traveling devices is driven and the other is stopped and a second turn in which the pair of traveling devices are driven in respective different directions; and the switching changing unit changes the first rotation speed or the second rotation speed according to a first operation amount or a second operation amount, the first operation amount being the operation amount of the travel operation member operated to make the first turn, the second operation amount being the operation amount of the travel operation member operated to make the second turn.

The switching changing unit increases the first rotation speed or the second rotation speed according to the first operation amount when the first turn is made, and reduces the first rotation speed or the second rotation speed according to the second operation amount when the second turn is made.

The working machine further comprises: a pair of travel motors to drive the pair of traveling devices, respectively; and a pair of travel pumps to drive the pair of travel motors, wherein the travel operation member is for operation of the pair of travel pumps.

One of the pair of travel pumps is a swash plate pump to change, according to a pilot pressure acting on a first pressure receiver and a second pressure receiver, a driving force to drive one of the pair of travel motors; and the other of the pair of travel pumps is a swash plate pump to change, according to a pilot pressure acting on a third pressure receiver and a fourth pressure receiver, a driving force to drive the other of the pair of travel motors.

The present invention makes it possible to flexibly change output depending on work. The present invention also makes it possible, when engine needs assistance, to effectively perform the assistance.

The following description discusses embodiments of a working machine according to the present invention with reference to drawings.

<FIG> is a side view of a working machine <NUM> according to the present invention. <FIG> illustrates a compact track loader as an example of a working machine. Note, however, that the working machine according to the present invention is not limited to a compact track loader and may be, for example, another type of loader working machine such as a skid-steer loader. The working machine according to the present invention may be a working machine other than loader working machines. Note that the description in the present invention is based on the assumption that the front end (left in <FIG>) of the working machine as viewed from an operator seated on an operator's seat of the working machine is "front" or forward", that the rear end (right in <FIG>) as viewed from the operator is "rear" or "rearward", that the left side (near side in <FIG>) as viewed from the operator is "left" or "leftward", and that the right side (far side in <FIG>) as viewed from the operator is "right" or "rightward". The description may be based on the assumption that a direction orthogonal to a front-rear direction of the machine body is "machine body width direction (width direction).

The working machine <NUM> includes a machine body <NUM>, a working device <NUM>, and a pair of traveling devices <NUM> and 4R.

A cabin <NUM> is mounted above a front portion of the machine body <NUM>. A rear portion of the cabin <NUM> is supported on a bracket of the machine body <NUM> swingably about a support shaft. A front portion of the cabin <NUM> is configured to be placed on the front portion of the machine body <NUM>. The cabin <NUM> is provided with an operator's seat <NUM> therein.

The pair of traveling devices <NUM> and 4R are composed of crawler-type traveling devices. The traveling device <NUM> is provided on one of the opposite sides (left side) of the machine body <NUM>, and the traveling device 4R is provided on the other of the opposite sides (right side) of the machine body <NUM>.

The working device <NUM> includes booms <NUM>, boom cylinders <NUM>, working tool cylinders <NUM>, and a working tool <NUM>. Each boom <NUM> is supported by a lift link <NUM> and a control link <NUM>. The boom cylinders <NUM>, which are each composed of a double-acting type hydraulic cylinder, are provided between proximal portions of the booms <NUM> and a lower rear portion of the machine body <NUM>. Concurrent extension or retraction of the boom cylinders <NUM> causes the booms <NUM> to swing up or down. Each boom <NUM> has, at a distal end thereof, a mounting bracket <NUM> supported pivotably about a lateral axis, and a back of the working tool <NUM> is attached to such mounting brackets <NUM> provided on left and right sides. That is, the working tool <NUM> is attached to distal ends of the booms <NUM>.

Furthermore, each of the working tool cylinders <NUM>, composed of a double-acting type hydraulic cylinder, is provided between a corresponding mounting bracket <NUM> and an intermediate portion of a distal portion of a corresponding boom <NUM>. Extension or retraction of the working tool cylinders <NUM> causes the working tool <NUM> to swing (scoop action, dump action).

The working tool <NUM> is configured to be attached to and detached from the mounting brackets <NUM>. The working tool <NUM> is, for example, an attachment (auxiliary attachment) such as a bucket, a hydraulic crusher, a hydraulic breaker, an angle broom, an earth auger, a pallet fork, a sweeper, a mower, or a snow blower.

The following description discusses the machine body.

As illustrated in <FIG>, the machine body <NUM> includes a right frame portion <NUM>, a left frame portion <NUM>, a front frame portion <NUM>, a bottom frame portion <NUM>, and a top frame portion <NUM>.

The right frame portion <NUM> forms a right portion of the machine body <NUM>. The left frame portion <NUM> forms a left portion of the machine body <NUM>. The front frame portion <NUM> forms a front portion of the machine body <NUM> and connects front portions of the right frame portion <NUM> and the left frame portion <NUM> together. The bottom frame portion <NUM> forms a bottom portion of the machine body <NUM> and connects lower portions of the right frame portion <NUM> and the left frame portion <NUM> together. The top frame portion <NUM> forms an upper rear portion of the machine body <NUM> and connects upper rear portions of the right frame portion <NUM> and the left frame portion <NUM> together.

Rear portions of the right frame portion <NUM> and the left frame portion <NUM> swingably support the booms <NUM> or the like. The right frame portion <NUM> and the left frame portion <NUM> are each provided with a track frame <NUM> and a motor mounting portion <NUM>.

As illustrated in <FIG>, the machine body <NUM> is provided with an engine <NUM>, a cooling fan <NUM>, a radiator, a motor/generator <NUM>, and a hydraulic drive device <NUM>. The engine <NUM> is an internal combustion engine such as a diesel engine or a gasoline engine. The cooling fan <NUM> is a fan for cooling which is driven by power from the engine <NUM>. The radiator cools cooling water for the engine <NUM>. The motor/generator <NUM> is a device to perform an assisting action in which the motor/generator <NUM> functions as a motor to assist the engine <NUM> in driving and an electricity generating action in which the motor/generator <NUM> functions as a generator to generate electricity using the power from the engine <NUM>. The motor/generator <NUM> is a motor/generator and employs a permanent magnet three-phase AC synchronous motor as a drive means.

The hydraulic drive device <NUM> is a device driven by power from the engine <NUM> and/or the motor/generator <NUM>, and outputs power mainly for work. The hydraulic drive device <NUM> is provided forward of the motor/generator <NUM>. The hydraulic drive device <NUM> includes a plurality of hydraulic pumps. The plurality of hydraulic pumps include, for example, as illustrated in <FIG> and <FIG>, a travel pump <NUM>, a travel pump 52R, a sub-pump P1, and a main pump P2.

The machine body <NUM> is provided with a battery <NUM> and an electricity control device <NUM>. The battery <NUM> stores electricity generated by the motor/generator <NUM> and supplies the stored electricity to the motor/generator <NUM> and the like.

With the working machine <NUM>, the hydraulic drive device <NUM> can be driven by power from the engine <NUM>, the hydraulic drive device <NUM> can be driven using both the engine <NUM> and the motor/generator <NUM>, and the motor/generator <NUM> can be caused to function to generate electricity using power from the engine <NUM>. That is, transmission of power in the working machine is of parallel hybrid type. The following description discusses a structure which transmits power from the engine <NUM> and the motor/generator <NUM>.

As illustrated in <FIG> and <FIG>, a housing <NUM> which houses a substantially disc-like flywheel and the motor/generator <NUM> is provided in front of the engine <NUM>. The motor/generator <NUM> includes: a connection part 63a connected to the flywheel; a rotor 63b fixed to the connection part 63a; a stator 63c provided on the rotor 63b; and a water jacket 63d provided outside the stator 63c.

The connection part 63a is in the form of a tube and has a rear end attached to the flywheel. The connection part 63a has an intermediate shaft 68a provided in the space defined thereby. The intermediate shaft 68a has a coupling 68b provided at a rear end thereof, and an outer edge of the coupling 68b is connected to the flywheel. Furthermore, the intermediate shaft 68a has a drive shaft of the hydraulic drive device <NUM> connected to a front end thereof.

Accordingly, when the engine <NUM> is driven, rotating power from a crankshaft (output shaft) 60a of the engine <NUM> is transmitted to the flywheel and causes the flywheel to rotate. As indicated by arrow F1 in <FIG>, the rotating power from the flywheel is transmitted from the coupling 68b to the intermediate shaft 68a and then transmitted from the intermediate shaft 68a to the drive shaft of the hydraulic drive device <NUM>, making it possible to drive the hydraulic drive device <NUM>.

Furthermore, as indicated by arrow F2 in <FIG>, the rotating power from the flywheel is transmitted via the connection part 63a to the rotor 63b. Therefore, transmission of the rotating power from the engine <NUM> to the rotor 63b (connection part 63a) allows the motor/generator <NUM> to function as a generator. On the other hand, supplying electricity stored in the battery <NUM> to the stator 63c allows the rotor 63b to rotate. As indicated by arrow F3, the rotating power from the rotor 63b can be transmitted to the flywheel via the connection part 63a. This makes it possible to cause the motor/generator <NUM> to function as an electric motor to assist the engine <NUM>.

<FIG> and <FIG> each show a hydraulic circuit (hydraulic system) of the working machine. <FIG> is a hydraulic system of a travel system, and <FIG> is a hydraulic system of a work system.

As shown in <FIG>, the hydraulic system of the travel system is a system to cause the traveling devices <NUM> and 4R to function using hydraulic pressure that occurs when the hydraulic drive device <NUM> is driven. The hydraulic system of the travel system includes: the sub-pump P1 which is a hydraulic pump to discharge hydraulic fluid; a first travel motor mechanism <NUM>; a second travel motor mechanism 31R; and a travel drive mechanism <NUM>.

The sub-pump P1 is composed of a fixed displacement gear pump. The sub-pump P1 is configured to discharge hydraulic fluid from a tank (hydraulic fluid tank). There is a discharge fluid passage <NUM>, which allows passage of hydraulic fluid, on the discharge side of the sub-pump P1. The discharge fluid passage <NUM> has a first charge fluid passage <NUM> connected to the discharge side thereof. The first charge fluid passage <NUM> extends to reach the travel drive mechanism <NUM>. The part of the hydraulic fluid discharged from the sub-pump P1 that is used for control may be referred to as pilot fluid, and the pressure of the pilot fluid may be referred to as pilot pressure.

The travel drive mechanism <NUM> is a mechanism to drive the first travel motor mechanism <NUM> and the second travel motor mechanism 31R, and includes a driver circuit (left driver circuit) <NUM> for driving the first travel motor mechanism <NUM> and a driver circuit (right driver circuit) 34R for driving the second travel motor mechanism 31R.

The driver circuits <NUM> and 34R include respective travel pumps <NUM> and 52R, respective speed change fluid passages <NUM> and 57i, and a second charge fluid passage <NUM>. The speed change fluid passages <NUM> and 57i are fluid passages connecting the travel pumps <NUM> and 52R with travel motors <NUM> and 36R. The second charge fluid passage <NUM> is a fluid passage connected to the speed change fluid passages <NUM> and 57i and supplies hydraulic fluid from the sub-pump P1 to the speed change fluid passages <NUM> and 57i. Each of the travel pumps <NUM> and 52R is a swash-plate variable displacement axial pump driven by power from the engine <NUM>. The travel pumps <NUM> and 52R each include pressure receivers 52a and 52b on which pilot pressure acts, and the swash plate angle is changed by the pilot pressure acting on the pressure receivers 52a and 52b. Changing the swash plate angle makes it possible to change the output of (amount of discharged hydraulic fluid from) the travel pumps <NUM> and 52R and the direction of discharge of hydraulic fluid. In other words, the travel pumps <NUM> and 52R, when the swash plate angle thereof is changed, thereby change a driving force outputted to the traveling devices <NUM> and 4R.

The first travel motor mechanism <NUM> is a mechanism which transmits power to a drive shaft of the traveling device <NUM> provided on the left side of the machine body <NUM>. The second travel motor mechanism 31R is a mechanism which transmits power to a drive shaft of the traveling device 4R provided on the right side of the machine body <NUM>. The first travel motor mechanism <NUM> includes travel motors <NUM> and 36R and a speed change mechanism.

Each of the travel motors <NUM> and 36R is, for example, a swash-plate variable displacement axial motor. The travel motor <NUM> is attached to the motor mounting portion <NUM> of the left frame portion <NUM> and transmits power for travel to the traveling device <NUM>. The travel motor 36R is attached to the motor mounting portion <NUM> of the right frame portion <NUM> and transmits power for travel to the traveling device 4R. Each of the travel motors <NUM> and 36R is a motor configured to change vehicle speed (rotation) to first speed stage or second speed stage. In other words, the travel motors <NUM> and 36R are motors configured to change the driving force for the working machine <NUM>, i.e., the driving force for the traveling devices <NUM> and 4R.

The speed change mechanism includes a swash plate switching cylinder 38a and a travel switching valve 38b. The swash plate switching cylinder 38a is a cylinder which extends and retracts to change the swash plate angle of a corresponding one of the travel motors <NUM> and 36R. The travel switching valve 38b is a valve which allows the swash plate switching cylinder 38a to extend/retract in either of two directions, and is a two-way switching valve which achieves switching between a first position 39a and a second position 39b. The travel switching valve 38b is caused to switch between the first and second positions 39a and 39b by a speed change switching valve <NUM>. The speed change switching valve <NUM> is connected to the discharge fluid passage <NUM> and is also connected to the travel switching valve 38b of the first travel motor mechanism <NUM> and the travel switching valve 38b of the second travel motor mechanism 31R. The speed change switching valve <NUM> is a two-way switching valve which achieves switching between a first position 44a and a second position 44b. When the speed change switching valve <NUM> is in the first position 44a, the pressure of hydraulic fluid acting on the travel switching valves 38b of the speed change mechanisms is set to a pressure corresponding to a predetermined speed (for example, first speed stage). When the speed change switching valve <NUM> is in the first position 44a, the pressure of the hydraulic fluid acting on the travel switching valves 38b is set to a pressure corresponding to a speed (second speed stage) higher than the predetermined speed (first speed stage). Thus, when the speed change switching valve <NUM> is in the first position 44a, each travel switching valve 38b is brought into the first position 39a, causing each swash plate switching cylinder 38a to retract and changing the speed stage of the travel motors <NUM> and 36R to first speed stage. When the speed change switching valve <NUM> is in the second position 44b, each travel switching valve 38b is brought into the second position 39b, causing each swash plate switching cylinder 38a to extend and changing the speed stage of the travel motors <NUM> and 36R to second speed stage. Note that the speed stage of the travel motors <NUM> and 36R is changed to first speed stage or second speed stage under control by a work control device <NUM>. For example, the work control device <NUM> is provided with an operation member <NUM> such as a switch (speed change switch) (see <FIG>). Upon shifting of the operation member <NUM> into first speed stage, the work control device <NUM> outputs a control signal to deenergize a solenoid of the speed change switching valve <NUM> to bring the speed change switching valve <NUM> into the first position 44a. Upon shifting of the operation member <NUM> into second speed stage, the work control device <NUM> outputs a control signal to energize the solenoid of the speed change switching valve <NUM> to bring the speed change switching valve <NUM> into the second position 44b.

As illustrated in <FIG>, the working machine <NUM> includes an operation device <NUM>. The operation device <NUM> is a device for operation of the traveling devices <NUM> and 4R, i.e., for operation of the first travel motor mechanism <NUM>, the second travel motor mechanism 31R, and the travel drive mechanism <NUM>. The operation device <NUM> includes a travel operation member <NUM> and a plurality of operation valves <NUM> (55a, 55b, 55c, and 55d). The plurality of operation valves <NUM> (55a, 55b, 55c, and 55d) are travel operation valves.

The travel operation member <NUM> is an operation member which is supported on the operation valves <NUM> and which swings sideways (along the machine body width direction) and along the front-rear direction. The plurality of operation valves <NUM> are operated by the same travel operation member <NUM>, i.e., by a single travel operation member <NUM>. The plurality of operation valves <NUM> function based on the swinging movement of the travel operation member <NUM>. Hydraulic fluid (pilot fluid) can be supplied from the sub-pump P1 through the discharge fluid passage <NUM> to the plurality of operation valves <NUM>. The plurality of operation valves <NUM> are the operation valve 55a, the operation valve 55b, the operation valve 55c, and the operation valve 55d.

The plurality of operation valves <NUM> and the travel drive mechanism <NUM> (travel pumps <NUM> and 52R) of the travel system are connected by a travel fluid passage <NUM>. The travel fluid passage <NUM> includes a first travel fluid passage 45a, a second travel fluid passage 45b, a third travel fluid passage 45c, a fourth travel fluid passage 45d, and a fifth travel fluid passage 45e. The first travel fluid passage 45a is a fluid passage connected to the pressure receiver (first pressure receiver) 52a of the travel pump <NUM>. The second travel fluid passage 45b is a fluid passage connected to the pressure receiver (second pressure receiver) 52b of the travel pump <NUM>. The third travel fluid passage 45c is a fluid passage connected to the pressure receiver (third pressure receiver) 52a of the travel pump 52R. The fourth travel fluid passage 45d is a fluid passage connected to the pressure receiver (fourth pressure receiver) 52b of the travel pump 52R. The fifth travel fluid passage 45e is a fluid passage which connects the operation valves <NUM>, the first travel fluid passage 45a, the second travel fluid passage 45b, the third travel fluid passage 45c, and the fourth travel fluid passage 45d. The fifth travel fluid passage 45e connects a plurality of shuttle valves <NUM> and the plurality of operation valves <NUM> (55a, 55b, 55c, and 55d).

Upon forward (in the direction indicated by arrow A1 in <FIG>) swinging movement of the travel operation member <NUM>, the operation valve 55a is operated, pilot pressure is determined by the operation valve 55a, the determined pilot pressure acts on the pressure receivers 52a of the travel pumps <NUM> and 52R, and the swash plate of each of the travel pumps <NUM> and 52R is tilted from a neutral position in a normal rotation direction, thereby causing the travel pumps <NUM> and 52R to discharge hydraulic fluid. It follows that output shafts <NUM> and 35R of the travel motors <NUM> and 36R rotate in the normal direction (rotate to cause forward travel) at a speed that is proportional to the amount of the swinging movement of the travel operation member <NUM>, and that the working machine <NUM> travels forward in a straight line.

Upon rearward (in the direction indicated by arrow A2 in <FIG>) swinging movement of the travel operation member <NUM>, the operation valve 55b is operated, pilot pressure is determined by the operation valve 55b, the determined pilot pressure acts on the pressure receivers 52b of the travel pumps <NUM> and 52R, and the swash plate of each of the travel pumps <NUM> and 52R is tilted from the neutral position in a reverse rotation direction, thereby causing the travel pumps <NUM> and 52R to discharge hydraulic fluid. It follows that the output shafts <NUM> and 35R of the travel motors <NUM> and 36R rotate in the reverse direction (rotate to cause rearward travel) at a speed that is proportional to the amount of the swinging movement of the travel operation member <NUM>, and that the working machine <NUM> travels rearward in a straight line.

Upon rightward (in the direction indicated by arrow A3 in <FIG>) swinging movement of the travel operation member <NUM>, the operation valve 55c is operated, pilot pressure is determined by the operation valve 55c, the determined pilot pressure acts on the pressure receiver 52a of the travel pump <NUM> and the pressure receiver 52b of the travel pump 52R, and the swash plate of the travel pump <NUM> is tilted in the normal rotation direction and the swash plate of the travel pump 52R is tilted in the reverse rotation direction. It follows that the output shaft <NUM> of the travel motor <NUM> on the left side rotates in the normal direction and the output shaft 35R of the travel motor 36R on the right side rotates in the reverse direction, so that the working machine <NUM> turns right (makes a spin turn). Upon leftward (in the direction indicated by arrow A4 in <FIG>) swinging movement of the travel operation member <NUM>, the operation valve 55d is operated, pilot pressure is determined by the operation valve 55d, the determined pilot pressure acts on the pressure receiver 52b of the travel pump <NUM> and the pressure receiver 52a of the travel pump 52R, and the swash plate of the travel pump <NUM> is tilted in the reverse rotation direction and the swash plate of the travel pump 52R is tilted in the normal rotation direction. It follows that the output shaft <NUM> of the travel motor <NUM> on the left side rotates in the reverse direction and the output shaft 35R of the travel motors 36R on the right side rotates in the normal direction, so that the working machine <NUM> turns left (makes a spin turn).

Upon diagonal swinging movement of the travel operation member <NUM>, the difference between the pilot pressure acting on the pressure receivers 52a and the pilot pressure acting on the pressure receivers 52b determines the direction and speed of rotation of the output shafts <NUM> and 35R of the travel motor <NUM> on the left side and the travel motor 36R on the right side, and the working machine <NUM> turns right (makes a right pivot turn) or turns left (makes a left pivot turn) while traveling forward or rearward.

The working machine <NUM> may include an anti-stall control valve <NUM>. The anti-stall control valve <NUM> is disposed in the fluid passage (discharge fluid passage <NUM>) between the plurality of operation valves <NUM> (55a, 55b, 55c, and 55d) and the sub-pump P1. The anti-stall control valve <NUM> is a proportional solenoid valve, and the degree of opening of the anti-stall control valve <NUM> is variable. The anti-stall control valve <NUM> is configured to determine, according to a decrease (drop) ΔE1 in rotation speed of the engine <NUM> (engine speed E1), pilot pressure (primary pilot pressure) which acts on the plurality of operation valves <NUM> (55a, 55b, 55c, and 55d). The rotation speed of the engine can be detected by an engine speed E1 sensor <NUM>. The engine speed E1 detected by the sensor <NUM> is inputted into the work control device <NUM>.

<FIG> shows a relationship between engine speed, travel primary pressure (primary pilot pressure), and setting lines L51 and L52. The setting line L51 represents a relationship between engine speed E1 and travel primary pressure where the decrease ΔE1 is less than a predetermined value (less than anti-stall reference value). The setting line L52 represents a relationship between engine speed E1 and travel primary pressure where the decrease ΔE1 is equal to or greater than the anti-stall reference value.

When the decrease ΔE1 is less than the anti-stall reference value, the work control device <NUM> adjusts the degree of opening of the anti-stall control valve <NUM> so that the relationship between the engine speed E1 and the travel primary pressure matches a reference pilot pressure represented by the setting line L51. When the decrease ΔE1 is equal to or greater than the anti-stall reference value, the work control device <NUM> adjusts the degree of opening of the anti-stall control valve <NUM> so that the relationship between the engine speed E1 and the travel primary pressure matches the setting line L52 which is below the reference pilot pressure. The travel primary pressure at a certain engine speed E1 is lower on the setting line L52 than on the setting line L51. That is, when focus is put on a single engine speed E1, the travel primary pressure on the setting line L52 is set to be lower than the travel primary pressure on the setting line L51. Accordingly, with the control based on the setting line L52, the pressure of hydraulic fluid entering the operation valves <NUM> is kept low (pilot pressure is kept low). It follows that the swash plate angle of the travel pumps <NUM> and 52R is adjusted, the load on the engine is reduced, and the engine is prevented from stalling. Note that, although <FIG> shows a single setting line L52, a plurality of setting lines L52 may be present. For example, the setting lines L52 may be set for respective engine speeds E1. Data indicative of the setting line L51 and the setting line L52, control parameters such as functions, or the like are preferably stored in the work control device <NUM>.

As illustrated in <FIG>, the hydraulic system of the work system is a system to cause the working device <NUM> and/or the like to function. The hydraulic system of the work system is a system to cause the working device <NUM> to function using hydraulic pressure that occurs when the hydraulic drive device <NUM> is driven. The hydraulic system of the work system includes a plurality of control valves <NUM> and a main pump P2 which is a hydraulic pump that discharges hydraulic fluid. The main pump P2 is located at a different position from the sub-pump P1, and is composed of a small displacement gear pump. The main pump P2 is configured to discharge hydraulic fluid from a hydraulic fluid tank. In particular, the main pump P2 mainly discharges hydraulic fluid to activate a hydraulic actuator.

There is a fluid passage 51f on the discharge side of the main pump P2. The fluid passage 51f has the plurality of control valves <NUM> connected thereto. The plurality of control valves <NUM> include a boom control valve 51a, a bucket control valve 51b, and an auxiliary control valve 51c. The boom control valve 51a is a valve to control the boom cylinders <NUM>, the bucket control valve 51b is a valve to control the working tool cylinders <NUM>, and the auxiliary control valve 51c is a valve to control a hydraulic actuator of the auxiliary attachment.

The booms <NUM> and the working tool <NUM> can be operated using a work operation member <NUM> of an operation device <NUM>. The work operation member <NUM> is an operation member which is supported on a plurality of operation valves <NUM> and which swings sideways (along the machine body width direction) and along the front-rear direction. The operation valves <NUM> provided at the bottom of the work operation member <NUM> can be operated by tilting operation of the work operation member <NUM>.

The plurality of operation valves <NUM> and the plurality of control valves <NUM> are connected to each other by a plurality of work fluid passages <NUM> (47a, 47b, 47c, and 47d). Specifically, the operation valve 59a is connected to the boom control valve 51a via the work fluid passage 47a. The operation valve 59b is connected to the boom control valve 51a via the work fluid passage 47b. The operation valve 59c is connected to the bucket control valve 51b via the work fluid passage 47c. The operation valve 59d is connected to the bucket control valve 51b via the work fluid passage 47d. The plurality of the operation valves 59a to 59d are each configured to determine, according to the operation of the work operation member <NUM>, the pressure of hydraulic fluid to be outputted.

Upon forward tilting movement of the work operation member <NUM>, the operation valve 59a is operated to output pilot pressure. The pilot pressure acts on a pressure receiver of the boom control valve 51a and hydraulic fluid having entered the boom control valve 51a is supplied to the rod side of each of the boom cylinders <NUM>, thereby lowering the booms <NUM>.

Upon rearward tilting movement of the work operation member <NUM>, the operation valve 59b is operated to output pilot pressure. The pilot pressure acts on another pressure receiver of the boom control valve 51a and hydraulic fluid having entered the boom control valve 51a is supplied to the bottom side of each of the boom cylinders <NUM>, thereby raising the booms <NUM>.

That is, the boom control valve 51a is configured to control the flow rate of hydraulic fluid flowing to the boom cylinders <NUM> according to the pressure of hydraulic fluid determined by the operation of the work operation member <NUM> (pilot pressure determined by the operation valve 59a, pilot pressure determined by the operation valve 59b).

Upon rightward tilting movement of the work operation member <NUM>, the operation valve 59c is operated and pilot pressure acts on a pressure receiver of the bucket control valve 51b. It follows that the bucket control valve 51b functions to cause the working tool cylinders <NUM> to extend, and the working tool <NUM> performs a dump action at a speed proportional to the amount of the tilting movement of the work operation member <NUM>.

Upon leftward tilting movement of the work operation member <NUM>, the operation valve 59d is operated and pilot fluid acts on another pressure receiver of the bucket control valve 51b. It follows that the bucket control valve 51b functions to cause the working tool cylinders <NUM> to retract, and the working tool <NUM> performs a scoop action at a speed proportional to the amount of the tilting movement of the work operation member <NUM>.

That is, the bucket control valve 51b is configured to control the flow rate of hydraulic fluid flowing to the working tool cylinders <NUM> according to the pressure of hydraulic fluid determined by the operation of the work operation member <NUM> (pilot pressure determined by the operation valve 59c, pilot pressure determined by the operation valve 59d). That is, the operation valves 59a, 59b, 59c, and 59d change the pressure of hydraulic fluid according to the operation of the work operation member <NUM>, and supply the hydraulic fluid having been subjected to pressure change to control valves such as the boom control valve 51a, the bucket control valve 51b, and/or the auxiliary control valve 51c.

The auxiliary attachment can be operated using a switch <NUM> provided in the vicinity of the operator's seat <NUM> (see <FIG>). The switch <NUM> is composed of, for example, a swingable seesaw-type switch, a slidable slide-type switch, or a push-type switch that can be pressed. The operation of the switch <NUM> is inputted into the work control device <NUM>. A first solenoid valve 56a and a second solenoid valve 56b, each composed of a solenoid valve or the like, open according to the operation amount of the switch <NUM>. It follows that pilot fluid is supplied to the auxiliary control valve 51c connected to the first solenoid valve 56a and the second solenoid valve 56b, and an auxiliary actuator of the auxiliary attachment is activated by hydraulic fluid supplied from the auxiliary control valve 51c.

The above-described embodiment employs a configuration in which the front or rear swinging movement of a single work operation member <NUM> raises or lowers the booms <NUM>, and the leftward or rightward swinging movement of the single work operation member <NUM> operates the working tool <NUM> such as a bucket. However, the following configuration may be employed instead: at least a pair of work operation members <NUM> are provided; swinging movement of one of the work operation members <NUM> raises or lowers the booms <NUM>; and swinging movement of the other of the work operation members <NUM> activates the working tool <NUM>. In such a case, the operation valves 59a and 59b determine the pilot pressure according to the swinging movement of the one of the work operation members <NUM>, and the operation valves 59c and 59d determine the pilot pressure according to the swinging movement of the other of the work operation members <NUM>. That is, the booms <NUM> and the working tool <NUM> may be operated concurrently (combined action may be performed).

Note that the operation amount of an operation member (work operation member <NUM>, travel operation member <NUM>) can be detected by an operation detecting device <NUM>. The operation detecting device <NUM> is connected to the work control device <NUM> (described later). The operation detecting device <NUM> includes a first operation detecting device 77A and a second operation detecting device 77B. The first operation detecting device 77A detects the operation amount of the work operation member <NUM> (work operation amount). The second operation detecting device 77B detects the operation amount of the travel operation member <NUM> (travel operation amount). The first operation detecting device 77A and the second operation detecting device 77B are each, for example, a position sensor to detect the position of the operation member.

<FIG> is a control block diagram of the working machine <NUM>. As illustrated in <FIG>, the electricity control device <NUM> and the work control device <NUM> are connected to each other. The electricity control device <NUM> includes the inverter 67A and the inverter control unit 67B. The inverter 67A includes, for example, a plurality of switching elements, and, for example, convers direct current into alternating current by, for example, turning ON and OFF the switching elements. The inverter 67A is connected to the motor/generator <NUM> and the battery <NUM>. The inverter control unit 67B is composed of a CPU, an electrical/electronic circuit, and/or the like. By outputting a predetermined signal to the inverter control unit 67B, the motor/generator <NUM> is caused to function as a motor or function as a generator. The amount of electricity stored in the battery <NUM> (remaining battery power) can be detected by the battery level sensor <NUM> of the battery <NUM>.

The work control device <NUM> is a device to perform various types of control relating to the working machine, and is composed of a CPU, an electrical/electronic circuit, and/or the like. The work control device <NUM> performs control relating to hydraulic pressure (hydraulic fluid) (such control is hydraulic pressure control). In the hydraulic pressure control, the work control device <NUM> energizes and deenergizes the solenoids of the speed change switching valve <NUM>, the first solenoid valve 56a, and the second solenoid valve 56b, as described earlier. The work control device <NUM> also acts as a controller to control the electricity control device <NUM>. The work control device <NUM> outputs an assist command to the inverter control unit 67B, and the inverter control unit 67B causes the motor/generator <NUM> to function as a motor. The work control device <NUM> outputs an electricity generation command to the inverter control unit 67B, and the inverter control unit 67B causes the motor/generator <NUM> to function as a generator. That is, the work control device <NUM> controls the motor/generator <NUM> to perform an assisting action in which the motor/generator <NUM> assists the engine <NUM> in driving and an electricity generating action in which the motor/generator <NUM> functions as a generator to generate electricity using power from the engine <NUM>. Note that the work control device <NUM> sends, to the electricity control device <NUM>, settings and commands regarding motoring torque in the case of the assisting action of the motor/generator <NUM> and regenerative torque in the case of the electricity generating action of the motor/generator <NUM>.

When the motor/generator <NUM> performs the assisting action, power from the engine <NUM> and the motor/generator <NUM> is transmitted to the hydraulic drive device <NUM>. When the motor/generator <NUM> performs the electricity generating action, power from the engine <NUM> is transmitted to the hydraulic drive device <NUM>, and electricity generated by the motor/generator <NUM> is stored in the battery <NUM>. The motor/generator <NUM> is driven by the electricity stored in the battery <NUM>.

Note that, although the work control device <NUM> and the electricity control device <NUM> are separate devices in the above-described embodiment, the work control device <NUM> and the electricity control device <NUM> may be composed of a single device. The above-described embodiment does not imply limitation.

The work control device <NUM> includes a storage unit 70a, a motoring torque setting unit 70b, a regenerative torque setting unit 70c, and an action control unit 70d. The storage unit 70a is composed of a nonvolatile memory or the like. The motoring torque setting unit 70b, the regenerative torque setting unit 70c, and the action control unit 70d are composed of electrical/electronic circuit(s) of the work control device <NUM>, program(s) stored in the CPU and/or the like of the work control device <NUM>, and/or the like. The storage unit 70a, the motoring torque setting unit 70b, the regenerative torque setting unit 70c, and the action control unit 70d may be provided in the electricity control device <NUM>.

The storage unit 70a stores therein control information for use when the motor/generator <NUM> performs the assisting action or charging action e.g., a control map as shown in <FIG>. The control map indicates: a relationship between the rotation speed of the engine <NUM> (engine speed E1) and switching between the assisting action and the charging action (switching between actions); a relationship between engine speed E1 and motoring torque in the case of the assisting action; and a relationship between engine speed E1 and regenerative torque in the case of the charging action. Note that, although the control information is a control map in the above-described embodiment, the relationship between engine speed E1 and switching between actions, the relationship between engine speed E1 and motoring torque in the case of the assisting action, and the relationship between engine speed E1 and regenerative torque in the case of the charging action may be represented by a control table, parameters, functions, and/or the like, and the above-described embodiment does not imply limitation.

The motoring torque setting unit 70b sets a motoring torque for the assisting action. As shown in <FIG>, the motoring torque setting unit 70b refers to control information such as a control map stored in the storage unit 70a, and sets the motoring torque to that corresponding to engine speed E1 using, for example, a standard line L1.

The regenerative torque setting unit 70c sets a regenerative torque for the electricity generating action. As shown in <FIG>, similarly to the motoring torque setting unit 70b, the regenerative torque setting unit 70c refers to control information and sets the regenerative torque to that corresponding to the engine speed E1 using, for example, the standard line L1. Note that the standard line L1 includes: a sloping line L1a in which the torque changes with engine speed E1; and a constant line L1b in which the torque is constant regardless of engine speed E1.

When the rotation speed of the engine is equal to or less than a first rotation speed N1, the action control unit 70d causes the assisting action to be performed by outputting the motoring torque set by the motoring torque setting unit 70b to the electricity control device <NUM>, and, when the rotation speed of the engine is equal to or greater than a second rotation speed N2 which is greater than the first rotation speed, the action control unit 70d causes the electricity generating action to be performed by outputting the regenerative torque set by the regenerative torque setting unit 70c to the electricity control device <NUM>.

The working machine <NUM> is configured such that the first rotation speed N1 and the second rotation speed N2, based on which switching to the assisting action or the electricity generating action is performed, can be changed when the work operation member <NUM> is operated. <FIG> shows a work operation amount BD and a work operation amount BU detected by the first operation detecting device 77A when the work operation member <NUM> is operated forward or rearward (when the boom cylinders <NUM> are caused to extend or retract). The work operation amount BD represents the operation amount detected when the boom cylinders <NUM> are caused to retract, i.e., the booms <NUM> are lowered, and the work operation amount BU represents the operation amount detected when the boom cylinders <NUM> are caused to extend, i.e., the booms <NUM> are raised.

<FIG> shows a work operation amount SU and a work operation amount SD detected by the second operation detecting device 77B when the work operation member <NUM> is operated leftward or rightward (when the working tool cylinders <NUM> are caused to extend or retract). The work operation amount SU represents the operation amount detected when the working tool cylinders <NUM> are caused to retract, i.e., the distal end of the working tool <NUM> is raised, and the work operation amount SD represents the operation amount detected when the working tool cylinders <NUM> are caused to extend, i.e., when the distal end of the working tool <NUM> is lowered. The work operation amounts BD, BU, SU, and SD each gradually increases as the work operation member <NUM> is tilted from the neutral position.

As illustrated in <FIG>, the work control device <NUM> includes a switching changing unit <NUM>. The switching changing unit <NUM> is composed of electrical/electronic circuit(s) of the work control device <NUM>, program(s) stored in the CPU and/or the like of the work control device <NUM>, and/or the like. The switching changing unit <NUM> may be provided in the electricity control device <NUM>.

The switching changing unit <NUM> changes the first rotation speed N1 and the second rotation speed N2 according to the work operation amounts BD, BU, SU, and/or SD of the work operation member <NUM>.

As shown in <FIG>, the switching changing unit <NUM> has switching information (first switching lines L31 and L32) indicating a relationship between the work operation amounts SU and SD and the first rotation speed N1 and indicating a relationship between the work operation amounts SU and SD and the second rotation speed N2. Upon operation of the work operation member <NUM>, the switching changing unit <NUM> changes the first rotation speed N1 and the second rotation speed N2 to values represented by the first switching lines L31 and L32. The first switching line L31 is a line based on which the first rotation speed N1 is set, and the second switching line L32 is a line based on which the second rotation speed N2 is set.

As indicated by the first switching lines L31 and L32 in <FIG>, when the work operation member <NUM> has not been operated and is in neutral position, the switching changing unit <NUM> sets the first rotation speed N1 and the second rotation speed N2 each to a reference engine speed E1. As indicated by the first switching lines L31 and L32, when the work operation member <NUM> is operated, the first rotation speed N1 and the second rotation speed N2 are gradually increased with the work operation amount SU or SD. Furthermore, as indicated by the first switching lines L31 and L32, when the work operation amount SU or SD has exceeded a predetermined value W20, the switching changing unit <NUM> sets the first rotation speed N1 and the second rotation speed N2 each to a fixed value.

As shown in <FIG>, the switching changing unit <NUM> has switching information (second switching lines L33 and L34) indicating a relationship between the work operation amounts BD and BU and the first rotation speed N1 and indicating a relationship between the work operation amounts BD and BU and the second rotation speed N2. Upon operation of the work operation member <NUM>, the switching changing unit <NUM> changes the first rotation speed N1 and the second rotation speed N2 to values represented by the second switching lines L33 and L34. The second switching line L33 is a line based on which the first rotation speed N1 is set, and the second switching line L34 is a line based on which the second rotation speed N2 is set.

As indicated by the second switching lines L33 and L34 in <FIG>, when the work operation member <NUM> has not been operated and is in neutral position, the switching changing unit <NUM> sets the first rotation speed N1 and the second rotation speed N2 each to a reference engine speed E1. As indicated by the second switching lines L33 and L34, when the work operation member <NUM> is operated, the first rotation speed N1 and the second rotation speed N2 are gradually increased with the work operation amount BD or BU. Furthermore, as indicated by the second switching lines L33 and L34, when the work operation amount BD or BU has exceeded a predetermined value W21, the switching changing unit <NUM> sets the first rotation speed N1 and the second rotation speed N2 each to a fixed value.

Note that, although the first rotation speed N1 and the second rotation speed N2 are increased with the work operation amount BU even when the boom cylinders <NUM> are caused to extend (when the booms <NUM> are raised) in the above-described embodiment, the following may be employed as indicated by lines L20 in <FIG>: upon operation to raise the booms <NUM>, the first rotation speed N1 and the second rotation speed N2 are each fixed at a reference value and do not change with the work operation amount BU; and, when the booms <NUM> are lowered, the first rotation speed N1 and the second rotation speed N2 are increased with the work operation amount BD.

Furthermore, when a plurality of the work operation members <NUM> are provided and the booms <NUM> and the working tool <NUM> can be operated separately (combined action can be performed), the switching changing unit <NUM> fixes the first rotation speed N1 and the second rotation speed N2 each at a reference value and do not change the first rotation speed N1 or the second rotation speed N2 during the combined action.

<FIG> and <FIG> show the action of changing the first rotation speed N1 and the second rotation speed N2 in the case where the operation member is operated.

As shown in <FIG>, the switching changing unit <NUM> refers to the work operation amounts BD, BU, SU and SD (S70). The switching changing unit <NUM> determines whether or not a combined action is performed (S71). For example, the switching changing unit <NUM> determines that a combined action is performed when both the work operation amount SU or SD and the work operation amount BD or BU are nonzero or when both the work operation amount SU or SD and the work operation amount BD or BU are greater than a predetermined operation amount (Yes in S71). If it is determined that a combined action is performed, the switching changing unit <NUM> keeps the first rotation speed N1 and the second rotation speed N2 each at a reference value (S72). The switching changing unit <NUM> determines whether or not the booms <NUM> are raised (S73). If the switching changing unit <NUM> determines that the work operation amount BU is equal to or greater than a predetermined amount and that the booms <NUM> are raised (Yes in S73), the switching changing unit <NUM> keeps the first rotation speed N1 and the second rotation speed N2 each at a reference value (S74). If it is determined that the booms <NUM> are not raised (No in S73), the switching changing unit <NUM> changes the first rotation speed N1 and the second rotation speed N2 according to the work operation amounts BD, SU and/or SD (S75). Note that, when the work operation amounts BD, BU, SU and SD are zero, the switching changing unit <NUM> keeps the first rotation speed N1 and the second rotation speed N2 each at a reference value.

In <FIG>, the first rotation speed N1 and the second rotation speed N2 are not changed and each kept at a reference value when the booms <NUM> are raised. However, instead of this, the first rotation speed N1 and the second rotation speed N2 may be changed with the work operation amounts BD, BU, SU and/or SD regardless of the action of the booms <NUM>.

Furthermore, the following may be employed: when the remaining power of the battery <NUM> is less than a predetermined remaining power, the switching changing unit <NUM> keeps the first rotation speed N1 and the second rotation speed N2 each at a reference value regardless of the values of the work operation amounts BD, BU, SU and SD, i.e., even if the work operation member <NUM> is operated.

Although both the first rotation speed N1 and the second rotation speed N2 are changed according to the work operation amounts BD, BU, SU, and/or SD in the above-described embodiment, either the first rotation speed N1 or the second rotation speed N2 may be changed.

Furthermore, the slope of the first switching lines L31 and L32 and the second switching lines L33 and L34, i.e., the amount of increase in the first rotation speed N1 or the second rotation speed N2 relative to the work operation amount BD or BU or the work operation amount SU or SD, may be set according to the operation amount of a setting operation member such as a slide switch or a rotary switch.

In the above-described embodiment, the switching changing unit <NUM> fixes the first rotation speed N1 and the second rotation speed N2 each at a reference value and does not change the first rotation speed N1 or the second rotation speed N2 in the case of a combined action in which the booms <NUM> and the working tool <NUM> are operated separately; however, the first rotation speed N1 and the second rotation speed N2 may each be fixed at a reference value in the case of a combined action in which the work system and the travel system are operated concurrently. Specifically, the first rotation speed N1 and the second rotation speed N2 may be set according to the work operation amount BD or BU or the work operation amount SU or SD of the work operation member <NUM> and a travel operation amount ST1 or ST2 of the travel operation member <NUM>. Note that, as will be described later, each of the travel operation amounts ST1 and ST2 is the operation amount for making a turn (spin turn, pivot turn).

As shown in <FIG>, the switching changing unit <NUM> refers to the work operation amounts BD, BU, SU, and SD and the travel operation amounts ST1 and ST2 (S100). The switching changing unit <NUM> determines whether or not a combined action is performed (S101). For example, the switching changing unit <NUM> determines that a combined action is performed when both the work operation amount BD or BU or the work operation amount SU or SD and the travel operation amount ST1 or ST2 are nonzero (Yes in S101). When it is determined that a combined action is performed, the switching changing unit <NUM> keeps the first rotation speed N1 and the second rotation speed N2 each at a reference value (S102). In particular, in the case where the work operation amount BD is nonzero and the booms <NUM> are raised and where the travel operation amount ST1 or ST2 is more than zero and the machine body <NUM> is making a turn, the switching changing unit <NUM> keeps the first rotation speed N1 and the second rotation speed N2 each at a reference value.

If it is determined that an action other than the combined action is performed (No in S101), the switching changing unit <NUM> changes the first rotation speed N1 and the second rotation speed N2 according to the work operation amounts BD, BU, SU, and/or SD (S103).

A working machine <NUM> comprises: a machine body <NUM>; an engine <NUM>: a motor/generator <NUM>; a working device <NUM>; a work operation member <NUM> for operation of the working device <NUM>; an action control unit 70d to cause the assisting action to be performed when an engine speed E1 is equal to or less than a first rotation speed N1 and cause the electricity generating action to be performed when the engine speed E1 is equal to or greater than a second rotation speed N2, the second rotation speed N2 being greater than the first rotation speed N1; and a switching changing unit <NUM> to change the first rotation speed N1 or the second rotation speed N2 according to a work operation amount BD, BU, SU or SD of the work operation member <NUM>. This makes it possible to change the point in time at which the assisting action or the electricity generating action is started (switching position) relative to the engine speed E1, according to the work operation amounts BD, BU, SU and SD of the work operation member <NUM> operated to cause the working device <NUM> to function. Accordingly, it is possible to flexibly change output depending on work.

The working device <NUM> includes a boom <NUM> swingably provided on the machine body <NUM>, a boom cylinder <NUM> to swing the boom <NUM>, a working tool <NUM> swingably provided on the boom <NUM>, and a working tool cylinder <NUM> to swing the working tool <NUM>; and the switching changing unit <NUM> makes a change of the first rotation speed N1 or the second rotation speed N2 according to the work operation amount SU or SD of the work operation member <NUM> operated to activate the working tool cylinder <NUM>. This makes it possible to change the combined output of the engine <NUM> and the motor/generator <NUM> according to the operation, when work is done with the working tool <NUM> such as a bucket.

When the work operation member <NUM> is operated to activate the boom cylinder <NUM> and the working tool cylinder <NUM>, the switching changing unit <NUM> does not make the change of the first rotation speed N1 or the second rotation speed N2 according to the work operation amount BD, BU, SU, or SD. With this configuration, when there is high load, e.g., when the boom <NUM> and the working tool <NUM> are operated concurrently, neither the first rotation speed N1 for the assisting action nor the second rotation speed N2 for the electricity generating action is changed, thereby making it possible to perform operation using the work operation member <NUM> while balancing between the assisting action and the electricity generating action.

When the work operation member <NUM> is operated to activate the boom cylinder <NUM> to raise the boom <NUM>, the switching changing unit <NUM> does not make the change of the first rotation speed N1 or the second rotation speed N2 according to the work operation amount BU. With this configuration, when there is high load, e.g., when the boom <NUM> is raised, neither the first rotation speed N1 for the assisting action nor the second rotation speed N2 for the electricity generating action is changed, thereby making it possible to perform operation using the work operation member <NUM> while balancing between the assisting action and the electricity generating action.

In the above-described embodiment, the first rotation speed N1 or the second rotation speed N2 is changed according to the work operation amount BD, BU, SU, or SD of the work operation member <NUM>; however, the first rotation speed N1 or the second rotation speed N2 may be changed according to the operation amount of the travel operation member <NUM> (travel operation amount).

As shown in <FIG>, the switching changing unit <NUM> has switching information (third switching lines L35 and L36) indicating a relationship between a travel operation amount (first operation amount) ST1 and the first rotation speed N1 and indicating a relationship between the travel operation amount ST1 and the second rotation speed N2. The travel operation amount ST1 is the travel operation amount of the travel operation member <NUM> swung leftward (to the left) or rightward (to the right) to make a pivot turn. Specifically, the third switching line L35 is a line based on which the first rotation speed N1 is set according to the travel operation amount ST1 for a pivot turn, and the third switching line L36 is a line based on which the second rotation speed N2 is set according to the travel operation amount ST1 for a pivot turn.

The switching changing unit <NUM> has switching information (fourth switching lines L37 and L38) indicating a relationship between a travel operation amount (second operation amount) ST2 and the first rotation speed N1 and indicating a relationship between the travel operation amount ST2 and the second rotation speed N2. The travel operation amount ST2 is the travel operation amount of the travel operation member <NUM> swung leftward (to the left) or rightward (to the right) to make a spin turn. Specifically, the fourth switching line L37 is a line based on which the first rotation speed N1 is set according to the travel operation amount ST2 for a spin turn, and the fourth switching line L38 is a line based on which the second rotation speed N2 is set according to the travel operation amount ST2 for a spin turn.

As indicated by the third switching lines L35 and L36 in <FIG>, when the work operation member <NUM> has not been operated and is in neutral position, the switching changing unit <NUM> sets the first rotation speed N1 and the second rotation speed N2 each to a reference engine speed E1. As indicated by the third switching lines L35 and L36, when the work operation member <NUM> is operated, the first rotation speed N1 and the second rotation speed N2 are gradually increased with the travel operation amount ST1.

Furthermore, as indicated by the fourth switching lines L37 and L38 in <FIG>, when the work operation member <NUM> has not been operated and is in neutral position, the switching changing unit <NUM> sets the first rotation speed N1 and the second rotation speed N2 each to a reference engine speed E1. As indicated by the fourth switching lines L37 and L38, when the work operation member <NUM> is operated, the first rotation speed N1 and the second rotation speed N2 are gradually reduced with the travel operation amount ST2.

That is, when the travel operation member <NUM> is operated to make a pivot turn, the switching changing unit <NUM> increases the first rotation speed N1 and the second rotation speed N2, whereas, when the travel operation member <NUM> is operated to make a spin turn, the switching changing unit <NUM> reduces the first rotation speed N1 and the second rotation speed N2.

<FIG> shows the action of changing the first rotation speed N1 and the second rotation speed N2 in the case where the operation member is operated.

As shown in <FIG>, the switching changing unit <NUM> determines whether or not the travel operation member <NUM> has been operated (S80) and, if it is determined that the travel operation member <NUM> has been operated (Yes in S80), the switching changing unit <NUM> determines whether the travel operation member <NUM> has been operated to make a pivot turn or a spin turn (S81). For example, the switching changing unit <NUM> refers to pressure detected by the pressure sensor <NUM> which detects pilot pressures (first pressure, second pressure, third pressure, and fourth pressure) in respective portions of the travel fluid passage <NUM> (first travel fluid passage 45a, second travel fluid passage 45b, third travel fluid passage 45c, and fourth travel fluid passage 45d). The first pressure is a pilot pressure acting in the first travel fluid passage 45a, the second pressure is a pilot pressure acting in the second travel fluid passage 45b, the third pressure is a pilot pressure acting in the third travel fluid passage 45c, and the fourth pressure is a pilot pressure acting in the fourth travel fluid passage 45d. It is noted here that if the first pressure, the second pressure, the third pressure, and the fourth pressure detected by the pressure sensor <NUM> are each more than zero, the first pressure and the second pressure are substantially the same, and the third pressure or the fourth pressure is equal to or greater than a predetermined pressure, the switching changing unit <NUM> determines that the travel operation member <NUM> has been operated to make a pivot turn. Alternatively, if the first pressure, the second pressure, the third pressure, and the fourth pressure detected by the pressure sensor <NUM> are each more than zero, the third pressure and the fourth pressure are substantially the same, and the first pressure and the second pressure are equal to or greater than a predetermined pressure, the switching changing unit <NUM> determines that the travel operation member <NUM> has been operated to make a pivot turn. On the other hand, if, among the first pressure, the second pressure, the third pressure, and the fourth pressure detected by the pressure sensor <NUM>, the first pressure or the second pressure is zero and the third pressure or the fourth pressure is zero, the switching changing unit <NUM> determines that the travel operation member <NUM> has been operated to make a spin turn. In other words, if the first pressure and the fourth pressure are equal to or greater than a predetermined pressure and the second pressure and the third pressure are substantially zero or if the second pressure and the third pressure are equal to or greater than a predetermined pressure and the first pressure and the fourth pressure are substantially zero, the switching changing unit <NUM> determines that the travel operation member <NUM> has been operated to make a spin turn.

Note that, although whether the travel operation member <NUM> has been operated to make a pivot turn or a spin turn is determined on the basis of the first pressure to the fourth pressure detected by the pressure sensor <NUM> in the above-described embodiment, there is no limitation on the method of determining.

If it is determined that the travel operation member <NUM> has been operated to make a pivot turn (Yes in S81), the switching changing unit <NUM> increases the first rotation speed N1 and the second rotation speed N2 by using the travel operation amount detected by the second operation detecting device 77B as the travel operation amount ST1 and applying the travel operation amount ST1 to the third switching lines L35 and L36 (S82). On the other hand, if it is determined that the travel operation member <NUM> has been operated to make a spin turn (No in S81), the switching changing unit <NUM> reduces the first rotation speed N1 and the second rotation speed N2 by using the travel operation amount detected by the second operation detecting device 77B as the travel operation amount ST2 and applying the travel operation amount ST2 to the fourth switching lines L37 and L38 (S83). Note that, if the travel operation member <NUM> has been operated to perform something other than the pivot turn and the spin turn, the switching changing unit <NUM> keeps the first rotation speed N1 and the second rotation speed N2 each at a reference value. The switching changing unit <NUM> keeps the first rotation speed N1 and the second rotation speed N2 each at a reference value also when the travel operation member <NUM> has not been operated (S84).

Note that the following may be employed: when the remaining power of the battery <NUM> is less than a predetermined remaining power, the switching changing unit <NUM> keeps the first rotation speed N1 and the second rotation speed N2 each at a reference value regardless of the values of the travel operation amounts ST1 and ST2, i.e., even if the travel operation member <NUM> is operated.

Although both the first rotation speed N1 and the second rotation speed N2 are changed on the basis of the travel operation amount ST1 or ST2 in the above-described embodiment, either the first rotation speed N1 or the second rotation speed N2 may be changed.

A working machine <NUM> comprises a switching changing unit <NUM> to change a first rotation speed N1 or a second rotation speed N2 according to an operation amount of a travel operation member <NUM> (travel operation amount ST1 or ST2). This makes it possible to change the point in time at which the assisting action or the electricity generating action is started (switching position) relative to engine speed E1, according to the travel operation amount ST1 or ST2 for the working machine to travel. Accordingly, it is possible to flexibly change output depending on travel.

The machine body <NUM> is configured to make a first turn (pivot turn) in which one of the pair of traveling devices <NUM> and 4R is driven and the other is stopped and a second turn (spin turn) in which the pair of traveling devices <NUM> and 4R are driven in respective different directions; and the switching changing unit <NUM> changes the first rotation speed N1 or the second rotation speed N2 according to a travel operation amount (first operation amount) ST1 for the first turn (pivot turn) or a travel operation amount (second operation amount) ST2 for the second turn (spin turn). This makes it possible to change output according to the travel operation amount ST1 or ST2 when the working machine <NUM> makes a pivot turn or a spin turn.

The switching changing unit <NUM> increases the first rotation speed N1 or the second rotation speed N2 according to the travel operation amount (first operation amount) ST1 when the first turn (pivot turn) is made, and reduces the first rotation speed N1 or the second rotation speed N2 according to the travel operation amount (second operation amount) ST2 when the second turn (spin turn) is made. With this, the first rotation speed N1 or the second rotation speed N2 is reduced so that the electricity generating action is more likely to occur when a load is applied such as when a spin turn is made, and the first rotation speed N1 or the second rotation speed N2 is increased so that the assisting action is more likely to occur when a load is small such as when a pivot turn is made. This makes it possible to reduce unnecessary assistance as a whole.

The working machine <NUM> comprises a pair of travel motors <NUM> and 36R to drive the pair of traveling devices <NUM> and 4R, respectively; and a pair of travel pumps <NUM> and 52R to drive the pair of travel motors <NUM> and 36R, wherein the travel operation member <NUM> is for operation of the pair of travel pumps <NUM> and 52R.

The travel pump <NUM>, which is one of the pair of travel pumps <NUM> and 52R, is a swash plate pump to change, according to a pilot pressure acting on a first pressure receiver and a second pressure receiver, a driving force to drive one of the pair of travel motors (travel motor 36R); and the travel pump 52R, which is the other of the pair of travel pumps <NUM> and 52R, is a swash plate pump to change, according to a pilot pressure acting on a third pressure receiver and a fourth pressure receiver, a driving force to drive the other of the pair of travel motors (travel motor 36R). With this, when, for example, the working machine <NUM> is caused to travel by the travel motors <NUM> and 36R and the travel pumps <NUM> and 52R, the first rotation speed N1 and the second rotation speed N2 are changed according to the travel operation amount ST1 or ST2, thereby making it possible to cause the working machine <NUM> to travel more stably. In particular, it is possible to provide improved maneuverability when operating the travel operation member <NUM>.

The work control device <NUM> may set, according to a change in engine speed E1 after operation of the operation member (work operation member <NUM>, travel operation member <NUM>), a point in time at which the assisting action is performed. The electricity control device <NUM> may set, according to a change in engine speed E1 after operation of the operation member (work operation member <NUM>, travel operation member <NUM>), a point in time at which the assisting action is performed.

<FIG> shows a relationship between changes M10 in the engine speed E1 and changes in turning speed V10. As shown in <FIG>, when the travel operation member <NUM> is operated to make a pivot turn or a spin turn at a point in time P30, the travel pumps <NUM> and 52R are switched to a normal rotation position or a reverse rotation position via a neutral position. With this, the changes M10 in the engine speed E1 are as follows: the engine speed E1 first increases from the point in time P30 and then starts to gradually decrease from a point in time P31 after a certain period of time T25. The action control unit 70d of the work control device <NUM> does not perform the assisting action between the point in time P30 and the point in time P31, and performs the assisting action at or after the point in time P3, i.e., after the engine speed E1 has decreased. That is, the action control unit 70d of the work control device <NUM> starts the assisting action when the turning speed V10 at which the machine body <NUM> is turned by a pair of traveling devices <NUM> and 4R has increased and the engine speed E1 has decreased after having increased. Note that the working machine <NUM> includes a rotation detecting device <NUM> to detect the rotation speed of the traveling devices <NUM> and 4R (see <FIG>). The rotation detecting device <NUM> is a sensor to detect rotation speeds M1 and M2 of the respective output shafts <NUM> and 35R of the travel motors <NUM> and 36R. The work control device <NUM> is configured to calculate the turning speed V10 on the basis of the rotation speeds M1 and M2 detected by the rotation detecting device <NUM>.

<FIG> shows a flow of how the action control unit 70d of the work control device <NUM> sets the point in time at which the assisting action is performed. Note that the description with reference to <FIG> is based on the assumption that, when the assisting action is performed, the motoring torque is set by the motoring torque setting unit 70b on the basis of the engine speed E1 as described earlier.

As shown in <FIG>, the action control unit 70d determines whether or not the travel operation member <NUM> has been operated (S91). If the travel operation member <NUM> has been operated (Yes in S91), the action control unit 70d determines whether or not the operation is to make a turn (operation to make a pivot turn, operation to make a spin turn) (S92). Note that whether or not the operation is to make a turn (operation to make a pivot turn, operation to make a spin turn) is determined on the basis of the first pressure, second pressure, third pressure, and fourth pressure detected by the pressure sensor <NUM>, as described earlier.

If the operation is to make a turn (operation to make a pivot turn, operation to make a spin turn) (Yes in S92), the action control unit 70d monitors the changes M10 in the engine speed E1 (S93). The action control unit 70d determines whether or not the upward trend of the engine speed E1 has changed to a downward trend (S94). If the upward trend of the engine speed E1 has not changed to a downward trend (No in S94), the assisting action is not performed. That is, the action control unit 70d does not cause the assisting action to be started. If the upward trend of the engine speed E1 has changed to a downward trend (Yes in S94), the action control unit 70d causes the assisting action to be started (S95). Whether or not the upward trend of the engine speed E1 has changed to a downward trend may be determined in the following manner: it can be determined that the upward trend of the engine speed E1 has changed to a downward trend if a moving average of changes in the engine speed E1 during a predetermined period (for example, <NUM>) is equal to or less than a predetermined value; or it can be determined that the upward trend of the engine speed E1 has changed to a downward trend if a decrease (rate of decrease) in the engine speed E1, obtained using a low-pass filter, is equal to or greater than a reference value.

Note that the action control unit 70d may cause the assisting action to be started when the turning speed V10 is equal to or greater than a predetermined speed and the upward trend of the engine speed E1 has changed to a downward trend.

A working machine <NUM> comprises a control device (work control device <NUM>, electricity control device <NUM>) to set, according to a change M10 in engine speed E1 after operation of the travel operation member <NUM>, a point in time at which the assisting action is performed. With this, for example, it is possible to determine whether the engine <NUM> needs assistance on the basis of the change M10 in the engine <NUM> and possible to achieve the following: assistance is provided when the assistance is needed and no assistance is provided when the assistance is not needed. This makes it possible to improve the efficiency of assistance.

The control device (work control device <NUM>, electricity control device <NUM>) causes the assisting action to be performed after the engine speed E1 has started decreasing after having increased. This makes it possible to achieve the following: assistance is not provided when the engine speed E1 is in an upward trend and the engine is not working at full power; and assistance is provided when the engine speed E1 has decreased.

The working machine <NUM> comprises an operation valve <NUM> (55a, 55b, 55c, and/or 55d) to determine a pilot pressure according to the operation of the travel operation member <NUM>, wherein an output of the hydraulic drive device <NUM> changes with the pilot pressure determined by the operation valve <NUM> (55a, 55b, 55c, and/or 55d). With this, the output of the hydraulic drive device <NUM> is done according to the operation of the operation valve <NUM>. This makes it possible to provide more effective assistance when, for example, the engine speed E1 turns into an upward trend or a downward trend.

The working machine <NUM> comprises a pair of traveling devices <NUM> and 4R provided on the machine body <NUM>; and a pair of travel motors <NUM> and 36R to drive the pair of traveling devices <NUM> and 4R, wherein the hydraulic drive device <NUM> includes a pair of travel pumps <NUM> and 52R to drive the pair of travel motors <NUM> and 36R. This makes it possible to provide effective assistance when, for example, the traveling devices <NUM> and 4R are caused to function by the travel motors <NUM> and 36R and the travel pumps <NUM> and 52R.

The control device (work control device <NUM>, electricity control device <NUM>) causes the assisting action to be started when a speed at which the machine body <NUM> is turned by the pair of traveling devices (turning speed) has increased and the engine speed E1 has decreased after having increased. This makes it possible to provide more effective assistance when the working machine <NUM> makes a turn and the engine speed E1 varies.

The above-described embodiment employs a configuration in which, when the work operation member <NUM> and the travel operation member <NUM> are operated, the operation valves <NUM> and <NUM> are caused to change pilot pressure; however, electrically driven operation members may be employed. That is, the operation devices <NUM> and <NUM> may be devices to cause the hydraulic drive device <NUM> and the control valves <NUM> and <NUM> to function using an electrical signal.

Note that, although the foregoing embodiments are described using the travel operation member <NUM> as an example, the foregoing configurations may apply to cases where the work operation member <NUM> is used to operate a hydraulic pump having a neutral position.

Claim 1:
A working machine (<NUM>) comprising:
a machine body (<NUM>);
an engine (<NUM>) provided on the machine body (<NUM>):
a motor/generator (<NUM>) to perform an assisting action in which the motor/generator (<NUM>) functions as a motor to assist the engine (<NUM>) in driving and an electricity generating action in which the motor/generator (<NUM>) functions as a generator to generate electricity using power from the engine (<NUM>);
a working device (<NUM>) configured to function using power from the engine (<NUM>) and the motor/generator (<NUM>); and
a work operation member (<NUM>) for operation of the working device (<NUM>);
the working machine (<NUM>) being characterized in that it further comprises:
an action control unit (70d) to cause the assisting action to be performed when a rotation speed of the engine (<NUM>) is equal to or less than a first rotation speed (N1) and cause the electricity generating action to be performed when the rotation speed of the engine (<NUM>) is equal to or greater than a second rotation speed (N2), the second rotation speed (N2) being greater than the first rotation speed (N1); and
a switching changing unit (<NUM>) to change the first rotation speed (N1) or the second rotation speed (N2) according to an operation amount of the work operation member (<NUM>).