JP6051364B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle.

  In a work vehicle such as a wheel loader, various work such as excavation work and cargo handling work is performed. A driver operates an operation member for a front working device including a work tool such as a bucket or an arm or an operation member for a travel drive device according to various works, and drives the front work device and the travel drive device. The front working device is driven by pressure oil discharged from a hydraulic pump driven by the engine.

  In a work vehicle, one that changes the discharge amount of a hydraulic pump in accordance with the operation amount of an operation member is known (see Patent Document 1). In the work vehicle of Patent Document 1, the hydraulic pump is configured so that the operation amount at the start of movement of the operation member during low idle rotation of the engine is substantially the same as the operation amount at the start of movement of the operation member during high idle rotation of the engine. The amount of tilt is controlled.

Japanese Patent Laid-Open No. 5-187406

  However, in the work vehicle of Patent Document 1, since the discharge amount of the hydraulic pump according to the operation direction and the operation amount of each actuator is not assigned to each of the plurality of actuators, further improvement is achieved from the viewpoint of improving the efficiency of the hydraulic pump. There was room for.

The work vehicle according to claim 1 is a work vehicle having an arm and a work tool that moves up and down by the rotation of the arm, and is driven by a hydraulic pump driven by a prime mover and pressure oil discharged from the hydraulic pump. The first hydraulic cylinder for the arm, the second hydraulic cylinder for the work tool driven by the hydraulic oil discharged from the hydraulic pump, and the flow of the hydraulic oil supplied from the hydraulic pump to the first hydraulic cylinder are controlled. A first directional control valve, a second directional control valve for controlling the flow of pressure oil supplied from the hydraulic pump to the second hydraulic cylinder, an arm operating member for operating the first directional control valve, and a second directional control valve According to the operation direction and the operation amount of the arm operation member detected by the first operation detection means, the first operation detection means for detecting the operation of the arm operation member, Comprising a discharge amount control means for controlling the discharge amount of flop, and a second operation detection means for detecting the operation of the work implement operation member, the operation of the implement operating member when the work implement operation member is operated solely The hydraulic pump discharge amount characteristic according to the direction and the operation amount is different from the hydraulic pump discharge amount characteristic according to the operation direction and operation amount of the arm operation member when the arm operation member is operated alone. The work tool is a bucket rotatably attached to the tip of the arm, and the second operation detecting means is configured to calculate a dump operation amount and a bucket which are operation amounts in a dump side operation direction for causing the bucket to perform a dump operation. When a rollback operation amount that is an operation amount in the rollback side operation direction for performing a rollback operation is detected, and the discharge amount control means detects a predetermined dump operation amount by the second operation detection means As compared to when a predetermined dumping operation amount and rollback operation amount equivalent has been detected by the second operation detection means and increasing the discharge quantity of the hydraulic pump.
According to a second aspect of the present invention, there is provided a work vehicle according to the first aspect, further comprising: a work state detection unit that detects a work state of the work vehicle, wherein the discharge amount control unit is a work detected by the work state detection unit. The discharge amount of the hydraulic pump is changed according to the operation amount of the arm operation member in a predetermined operation direction according to the state.
According to a third aspect of the present invention , in the work vehicle according to the first or second aspect , the first operation detection means is a lift-up that is an operation amount in the arm raising side operation direction for raising the work tool. the manipulated variable us and the work implement is detected the lift-down operation amount is an operation amount of the arm down side operation direction for lowering the discharge amount control means, a predetermined lift-down operation amount by the first operation detection means is detected In this case, the discharge amount of the hydraulic pump is made smaller than when the first operation detecting means detects a lift-up operation amount equivalent to a predetermined lift-down operation amount.
According to a fourth aspect of the present invention, there is provided the work vehicle according to the third aspect , wherein the hydraulic pressure corresponding to the increase in the lift-up operation amount when the lift-up operation amount detected by the first operation detecting means is equal to or greater than a predetermined value. The increase rate of the discharge amount of the pump is smaller than the increase rate of the discharge amount of the hydraulic pump according to the increase of the lift-up operation amount when the lift-up operation amount is less than a predetermined value.
The work vehicle according to claim 5 is the work vehicle according to claim 3 or 4 , wherein the first directional control valve uses the bottom oil chamber of the first hydraulic cylinder as a tank pressure, A power-down position for supplying pressure oil, and a float-down position in which the bottom oil chamber and the rod-side oil chamber of the first hydraulic cylinder are respectively tank pressures, and the power-down position is increased according to an increase in the lift-down operation amount. The discharge amount control means changes the discharge amount of the hydraulic pump according to the increase in the lift down operation amount when the lift down operation amount detected by the first operation detection means is less than a predetermined amount. When the lift-down operation amount detected by the first operation detecting means is greater than or equal to a predetermined amount, the discharge amount of the hydraulic pump is decreased according to the increase in the lift-down operation amount.
The work vehicle according to claim 6 is the work vehicle according to claim 2, wherein the work state detecting means detects at least whether the work vehicle is in an excavation work state, and the discharge amount control means is a work state. When the excavation work state is detected by the detecting means, when the excavation work state is not detected, the discharge amount of the hydraulic pump according to the operation amount in the arm raising side operation direction of the arm operation member for raising the work tool It is characterized by being made smaller than .
The work vehicle according to claim 7 is the work vehicle according to any one of claims 1 to 6, wherein the discharge amount control means is configured such that the arm operation member and the work tool operation member are operated simultaneously. In this case, the larger one of the discharge amount of the hydraulic pump according to the operation amount of the arm operation member and the discharge amount of the hydraulic pump according to the operation amount of the work tool operation member is selected.

  According to the present invention, the hydraulic pump can be efficiently operated according to the operation direction and the operation amount of the operation member.

1 is an external side view of a series hybrid wheel loader that is an example of a work vehicle according to the present invention. The schematic diagram which shows the operation member arrange | positioned in the driver's cab of a wheel loader. The figure which shows an example of a structure of a wheel loader. The figure which shows the working hydraulic device of a wheel loader. The figure which shows the relationship between lever operation amount and pilot pressure. The figure which shows the operation direction of an arm operation lever and a bucket operation lever. The schematic diagram which shows the operation direction of the arm and bucket corresponding to the operation direction of the lever shown in FIG. The block diagram explaining the function of a main controller. The figure which shows an example of an allowable charging power map. The block diagram explaining the function of a hydraulic pressure calculation part. The figure which shows an example of a pump request | requirement flow volume map. (A) is a figure which shows the characteristic of the pump request | requirement flow volume according to the lift-up operation amount at the time of excavation work, (b) is a figure which shows the characteristic of the pump request | requirement flow volume according to the lift-up operation amount at the time of non-digging work. (A) is a figure which shows the characteristic of the pump request | requirement flow volume according to the liftdown operation amount, (b) is a figure which shows the characteristic of the pump request | requirement flow rate according to the rollback operation amount and the dump operation amount. The figure explaining the excavation work by a wheel loader. The figure explaining the cargo handling work (loading work to a truck) by a wheel loader. The figure which shows an example of an accelerator request | requirement torque map.

Hereinafter, an embodiment of a work vehicle according to the present invention will be described with reference to the drawings.
FIG. 1 is an external side view of a series hybrid type wheel loader 100 as an example of a work vehicle according to the present invention. For convenience of explanation, the present embodiment defines the front-rear and vertical directions as described in the drawings.

  As shown in FIG. 1, the wheel loader 100 includes a front vehicle body 140F and a rear vehicle body 140R. The front vehicle body 140F includes a lift arm (hereinafter simply referred to as the arm 101), a bucket 102, a front wheel 141F, and the like. The rear vehicle body 140R includes a cab 151, an engine compartment 152, a rear wheel 141R, and the like. Note that the front wheel 141F and the rear wheel 141R will be described as wheels 141 when collectively referred to.

  An arm 101 is connected to the front vehicle body 140F so as to be rotatable in the vertical direction, and the arm 101 is rotated in the vertical direction by driving the arm cylinder 110. A bucket 102 is attached to the tip of the arm 101 so as to be rotatable in the front-rear direction, and the bucket 102 is rotated in the front-rear direction by driving the bucket cylinder 120. For this reason, when the arm 101 is rotated upward, the bucket 102 is raised, and when the arm 101 is rotated downward, the bucket 102 is lowered. Note that when the arm 101 rotates upward and the tip of the arm 101 moves upward, the arm 101 simply rises or the arm 101 lifts up. The fact that the arm 101 rotates downward and the tip of the arm 101 moves downward also simply means that the arm 101 is lowered or the arm 101 is lifted down.

  The front vehicle body 140F and the rear vehicle body 140R are pivotally connected to each other by a joint portion having a center pin 109. When the pair of steering cylinders 130 extend and retract as the driver steers, the front vehicle body 140R 140F is refracted left and right.

  An arm angle sensor 204 that detects a rotation angle of the arm 101 with respect to the front vehicle body 140F is provided on the rotation shaft of the arm 101. The arm angle sensor 204 is, for example, a rotary potentiometer.

  FIG. 2 is a schematic view showing an operation member arranged in the cab 151 of the wheel loader 100. The driver's cab 151 is provided with a steering wheel 303 for the driver to steer the wheel loader 100 and an ignition switch 164 for the driver to start or stop the engine 10. The steering wheel 303 is operated when the steering cylinder 130 is expanded and contracted. The driver operates the steering wheel 303 to expand and contract the steering cylinder 130 to adjust the steering angle of the wheel loader 100 and turn the wheel loader 100.

  A forward / reverse switching lever 161 is disposed below the steering wheel 303 so as to protrude from the side of the steering column. The forward / reverse switching lever 161 outputs a forward signal for instructing forward movement, a reverse signal for instructing backward movement, and a neutral signal for instructing neutrality. On the floor surface of the cab 151, an accelerator pedal 162 and a pair of brake pedals 163 interlocking with the left and right are arranged.

  The driver can drive the wheel 141 and drive the wheel loader 100 by operating the accelerator pedal 162, the brake pedal 163, and the forward / reverse switching lever 161.

  The cab 151 is provided with an arm operation lever 301 for lifting or lowering the arm 101 and a bucket operation lever 302 for rotating the bucket 102 in the backward or forward tilt direction. . Note that the rotation of the bucket 102 in the backward tilt direction is also referred to as the bucket 102 rolling back. The rotation of the bucket 102 in the forward tilt direction is also referred to as the bucket 102 dumping.

  The arm operation lever 301 outputs a lift-up (up) command / lift-down (down) command of the arm 101 to expand and contract the arm cylinder 110. The bucket operation lever 302 outputs a cloud / dump command for the bucket 102 to expand and contract the bucket cylinder 120.

  The driver operates the arm operation lever 301 and the bucket operation lever 302 to expand and contract the arm cylinder 110 and the bucket cylinder 120 to control the height and inclination of the bucket 102 and perform excavation and cargo handling operations.

  FIG. 3 is a diagram illustrating an example of the configuration of the wheel loader 100. Wheel loader 100 includes a main controller 200, an engine 10, an engine controller 10c, a travel electric device 100E, a work hydraulic device 100H, and a travel drive device 100D.

  FIG. 4 is a diagram illustrating a work hydraulic device 100H of the wheel loader 100. The working hydraulic device 100H includes a main pump 11 and a pilot pump 12 that discharge pressure oil, an arm cylinder 110 that rotates and drives an arm 101 by pressure oil supplied from the main pump 11, and pressure oil supplied from the main pump 11. The bucket cylinder 120 that rotationally drives the bucket 102 and the working hydraulic circuit HC.

  The main pump 11 supplies pressure oil to each hydraulic cylinder of the wheel loader 100, that is, the steering cylinder 130, the arm cylinder 110, and the bucket cylinder 120 (not shown in FIGS. 3 and 4). The pilot pump 12 supplies pressure oil to the pilot valves 301 a and 301 b of the arm operation lever 301 and the pilot valves 302 a and 302 b of the bucket operation lever 302. As shown in FIG. 3, the rotation shafts of the main pump 11 and the pilot pump 12 are provided coaxially with the drive shaft of the engine 10.

  When the main pump 11 and the pilot pump 12 are driven by the engine 10, the working oil in the working oil tank 19 is supplied to the working hydraulic circuit HC. The main pump 11 of this embodiment is a swash plate type variable displacement hydraulic pump whose capacity can be changed by changing the tilt angle of the swash plate 11a. The displacement of the main pump 11 (discharge amount per one rotation of the pump) is adjusted by the pump regulator 211.

  As shown in FIG. 4, the working hydraulic circuit HC includes an arm control valve 310, a bucket control valve 320, and a main relief valve 330. The arm control valve 310 controls the drive of the arm cylinder 110 by controlling the direction and flow rate of the pressure oil supplied from the main pump 11 to the arm cylinder 110. The bucket control valve 320 controls the drive of the bucket cylinder 120 by controlling the direction and flow rate of the pressure oil supplied from the main pump 11 to the bucket cylinder 120. The main relief valve 330 defines the maximum pressure of the pressure oil discharged from the main pump 11.

  The arm control valve 310 and the bucket control valve 320 are open center type directional control valves, and are provided in a center bypass line 390 that connects the main pump 11 and the hydraulic oil tank 19. That is, to the center bypass line 390, the arm control valve 310 and the bucket control valve 320 are connected in tandem. The arm control valve 310 and the bucket control valve 320 are connected in parallel to the main pump 11 by a parallel oil passage 391 branched from a center bypass line 390 on the upstream side of the arm control valve 310.

  Arm control valve 310 and bucket control valve 320 are operated by arm operation lever 301 and bucket operation lever 302, respectively. Each of the arm operation lever 301 and the bucket operation lever 302 is a hydraulic pilot type operation lever. The arm operation lever 301 includes pilot valves 301a and 301b for reducing the pressure oil discharged from the pilot pump 12 and outputting a pilot pressure corresponding to the operation amount. The bucket operation lever 302 includes pilot valves 302a and 302b that depressurize the pressure oil discharged from the pilot pump 12 and output a pilot pressure corresponding to the operation amount. The arm control valve 310 and the bucket control valve 320 are controlled by the pilot pressure output from the pilot valves 301a, 301b, 302a, and 302b, thereby controlling the amount of displacement. Details of the arm control valve 310 and the bucket control valve 320 will be described later.

  FIG. 5 is a diagram showing the relationship between the lever operation amount L and the pilot pressure p. As shown in FIG. 5, the pilot pressure p is output from the pilot valves 301 a and 301 b according to the lever operation amount L of the arm operation lever 301. When the lever operation amount L is less than the predetermined value La, the pilot pressure p does not increase. When the lever operation amount L reaches the predetermined value La, the pilot pressure p increases to the predetermined value pa.

  When the lever operation amount L is in the range of values La to Lb, the pilot pressure p increases in proportion to the lever operation amount L. When the lever operation amount L is Lb, the pilot pressure p output from the pilot valves 301a and 301b is pb. The same applies to the relationship between the lever operation amount of the bucket operation lever 302 and the pilot pressure output from the pilot valves 302a and 302b. In the present specification, the pilot pressure output from the pilot valve 301a is referred to as an arm raising pilot pressure, and the pilot pressure output from the pilot valve 301b is referred to as an arm lowering pilot pressure. The pilot pressure output from the pilot valve 302a is referred to as a rollback pilot pressure, and the pilot pressure output from the pilot valve 302b is referred to as a dump pilot pressure.

  As shown in FIG. 4, the arm control valve 310 has a neutral position (N), a rise position (R), a power-down position (D), and a float-down position (F). The arm control valve 310 changes the spool stroke amount according to the pilot pressure (arm raising pilot pressure and arm lowering pilot pressure), and changes the direction and flow rate of the pressure oil supplied to the arm cylinder 110. The arm control valve 310 has a P port, a P ′ port, a T port, an A port, a T ′ port, and a B port.

  The bucket control valve 320 has a neutral position (N), a rollback position (R), and a dump position (D). The bucket control valve 320 changes the spool stroke amount according to the pilot pressure (rollback pilot pressure and dump pilot pressure) to change the direction and flow rate of the pressure oil supplied to the bucket cylinder 120. The bucket control valve 320 has a P port, a P ′ port, a T port, an A port, a T ′ port, and a B port.

  The P port of the arm control valve 310 is connected to the main pump 11 via a check valve 392. The P ′ port of the arm control valve 310 is connected to the main pump 11, the T ′ port is connected to the P ′ port of the bucket control valve 320, and the T port is connected to the hydraulic oil tank 19. The A port of the arm control valve 310 is connected to the bottom side oil chamber 110 a of the arm cylinder 110, and the B port is connected to the rod side oil chamber 110 b of the arm cylinder 110.

  The P port of the bucket control valve 320 is connected to the T ′ port of the arm control valve 310 via the check valve 393, and is further connected to the main pump via the throttle 394 and the check valve 395 on the parallel oil passage 391. 11 is connected. The P ′ port of the bucket control valve 320 is connected to the T ′ port of the arm control valve 310, and the T port and T ′ port are connected to the hydraulic oil tank 19. The A port of the bucket control valve 320 is connected to the bottom side oil chamber 120 a of the bucket cylinder 120, and the B port is connected to the rod side oil chamber 120 b of the bucket cylinder 120.

  The operation based on the arm operation lever 301 and the bucket operation lever 302 will be described with reference to FIGS. 6 is a diagram showing the operation directions of the arm operation lever 301 and the bucket operation lever 302, and FIG. 7 is a schematic diagram showing the operation directions of the arm 101 and the bucket 102 corresponding to the operation directions of the lever shown in FIG.

  As shown in FIG. 6, when the arm operation lever 301 is disposed at the neutral operation position (N) and neither the arm raising pilot pressure nor the arm lowering pilot pressure acts on the arm control valve 310 shown in FIG. The spool of the control valve 310 is in the neutral position (N). When the spool of the arm control valve 310 is in the neutral position (N), the P ′ port and the T ′ port are connected, and the P port and the T port are disconnected from the A port and the B port.

  As shown in FIG. 6, when the bucket operation lever 302 is disposed at the neutral operation position (N) and neither the rollback pilot pressure nor the dump pilot pressure acts on the bucket control valve 320 shown in FIG. The spool of the control valve 320 is in the neutral position (N). When the spool of the bucket control valve 320 is in the neutral position (N), the P ′ port and the T ′ port are connected, and the P port and the T port are disconnected from the A port and the B port.

  As shown in FIG. 6, when the driver operates the arm operation lever 301 from the neutral operation position (N) in the arm raising (RISE) side operation direction, the arm raising pilot pressure acts on the arm control valve 310 shown in FIG. Therefore, the spool of the arm control valve 310 moves from the neutral position (N) toward the rise position (R). The opening area of the flow path connecting the P ′ port and the T ′ port is gradually reduced according to the magnitude of the arm raising pilot pressure, the opening area of the flow path connecting the P port and the A port, and the T port and B The opening area of the flow path connecting the ports gradually increases. At the rise position (R), the pressure oil from the main pump 11 is supplied to the bottom side oil chamber 110a of the arm cylinder 110, and the rod side oil chamber 110b of the arm cylinder 110 is connected to the hydraulic oil tank 19 so that the rod side The oil chamber 110b becomes the tank pressure. Therefore, when the driver operates the arm operation lever 301 in the arm raising side operation direction, the cylinder rod of the arm cylinder 110 is extended, and the arm 101 is rotated upward as shown in FIG. To rise. The operation amount in the arm raising side operation direction for raising the bucket 102 is defined as “lift-up operation amount”.

  As shown in FIG. 6, when the driver operates the arm operation lever 301 from the neutral operation position (N) in the arm down (DOWN) side operation direction, the arm lowering pilot pressure acts on the arm control valve 310 shown in FIG. Therefore, the spool of the arm control valve 310 moves from the neutral position (N) toward the power down position (D). The opening area of the flow path connecting the P ′ port and the T ′ port is gradually reduced according to the magnitude of the arm lowering pilot pressure, the opening area of the flow path connecting the P port and the B port, and the T port and A The opening area of the flow path connecting the ports gradually increases. In the power-down position (D), the pressure oil from the main pump 11 is supplied to the rod-side oil chamber 110b of the arm cylinder 110, and the bottom-side oil chamber 110a of the arm cylinder 110 is connected to the hydraulic oil tank 19 to be bottom. The side oil chamber 110a is set to tank pressure. Therefore, when the driver operates the arm operation lever 301 in the arm lowering operation direction, the cylinder rod of the arm cylinder 110 is retracted, and the arm 101 is rotated downward as shown in FIG. The power drops. The operation amount in the arm lowering operation direction for lowering the bucket 102 is defined as “lift-down operation amount”.

  From the state where the arm control valve 310 is in the power down position (D), as shown in FIG. 6, when the driver further operates the arm operation lever 301 in the direction of the arm lowering (DOWN) operation side, the arm control valve The spool 310 moves from the power down position (D) toward the float down position (F). As shown in FIG. 4, in the float down position (F), the arm control valve 310 blocks the P port, connects the P ′ port and the T ′ port, and connects the A port and the B port. Both are connected to the T port. In the float down position (F), each of the rod side oil chamber 110b and the bottom side oil chamber 110a of the arm cylinder 110 is set to the tank pressure. As described above, the arm control valve 310 is configured to switch from the power-down position (D) to the float-down position (F) in accordance with an increase in the lift-down operation amount.

  When the arm operation lever 301 is fully operated in the arm lowering operation direction, the well-known detent solenoid 301d (see FIG. 4) is excited, and the arm operation lever 301 is moved to its position (hereinafter referred to as a float down operation). Electromagnetic holding is performed at a position (F). As a result, the arm control valve 310 is held in a state of being switched to the float down position (F). As a result, as shown in FIG. 7, the arm 101 freely descends, and when the bucket 102 contacts the ground, the arm 101 freely moves up and down with an external force.

  As shown in FIG. 6, when the driver operates the bucket operation lever 302 in the operation direction on the rollback (ROLLBACK) side from the neutral operation position (N), the rollback pilot pressure is applied to the bucket control valve 320 shown in FIG. Therefore, the spool of the bucket control valve 320 moves from the neutral position (N) toward the rollback position (R). In accordance with the magnitude of the rollback pilot pressure, the opening area of the flow path connecting the P ′ port and the T ′ port gradually decreases, the opening area of the flow path connecting the P port and the A port, and the T port The opening area of the flow path connecting the B port increases gradually. In the rollback position (R), the pressure oil from the main pump 11 is supplied to the bottom side oil chamber 120a of the bucket cylinder 120, and the rod side oil chamber 120b of the bucket cylinder 120 is connected to the hydraulic oil tank 19 to connect the rod. The side oil chamber 120b becomes the tank pressure. Therefore, when the driver operates the bucket operation lever 302 in the rollback side operation direction, the cylinder rod of the bucket cylinder 120 is extended, and the bucket 102 is rotated backward as shown in FIG. Rollback operation is performed. Note that an operation amount in the rollback side operation direction for causing the bucket 102 to perform a rollback operation is defined as a “rollback operation amount”.

  As shown in FIG. 6, when the driver operates the bucket operation lever 302 from the neutral operation position (N) to the dump (DUMP) side operation direction, dump pilot pressure acts on the bucket control valve 320 shown in FIG. The spool of the bucket control valve 320 moves from the neutral position (N) toward the dump position (D). In accordance with the magnitude of the dump pilot pressure, the opening area of the flow path connecting the P ′ port and the T ′ port gradually decreases, the opening area of the flow path connecting the P port and the B port, and the T port and A The opening area of the flow path connecting the ports gradually increases. At the dump position (D), the pressure oil from the main pump 11 is supplied to the rod side oil chamber 120b of the bucket cylinder 120, and the bottom side oil chamber 120a of the bucket cylinder 120 is connected to the hydraulic oil tank 19 so as to be on the bottom side. The oil chamber 120a becomes the tank pressure. Therefore, when the driver operates the bucket operation lever 302 in the dumping operation direction, the cylinder rod of the bucket cylinder 120 is retracted, and the bucket 102 is rotated forwardly as shown in FIG. Be operated. The operation amount in the operation direction on the dump side for causing the bucket 102 to perform the dump operation is defined as “dump operation amount”.

  The travel drive device 100D will be described with reference to FIG. Travel drive device 100D includes axles 142F and 142R, differential devices 143F and 143R, and propeller shaft 145, and is driven by travel motors 402f and 402r. The rotor of the traveling motor 402f and the rotor of the traveling motor 402r are connected via a propeller shaft 145 having universal joints at both ends.

  The pair of front wheels 141F are connected to the front wheel side axle 142F, respectively. The front wheel side axle 142F is connected to a differential device 143F, and the differential device 143F is connected to the rotor shaft of the front traveling motor 402f via a connecting portion 146 formed of a pair of universal joints. Each of the pair of rear wheels 141R is connected to the rear wheel side axle 142R. The rear wheel axle 142R is connected to a differential device 143R, and the differential device 143R is connected to the rotor shaft of the rear traveling motor 402r via a connecting portion 147 formed of a pair of universal joints.

  The traveling electric apparatus 100E will be described with reference to FIG. The traveling motor apparatus 100E includes a generator motor 401, an inverter for a generator motor (hereinafter referred to as an M / G inverter 410), traveling motors 402f and 402r, and an inverter for a traveling motor (hereinafter referred to as traveling inverters 420f and 420r). A power storage element 404 such as a capacitor, and a converter 440.

  In the generator motor 401, a rotor is attached to a rotary shaft that is coaxial with the drive shaft of the engine 10, and a stator is disposed on the outer periphery of the rotor. The generator motor 401 is driven in either a generator mode or a motor mode. When the generator mode is selected, the generator motor 401 generates power when the rotor is rotated by the engine 10. The M / G inverter 410 converts AC power generated by the generator motor 401 into DC power having a predetermined voltage. When the motor mode is selected, the generator motor 401 is supplied with AC power from the M / G inverter 410 and functions as a motor. The rotating shaft of the generator motor 401 is connected to the rotating shaft of the engine 10 and the rotating shaft of the main pump 11. Therefore, the output torque of the generator motor 401 is given to the main pump 11.

  Traveling motors 402f and 402r are connected to power storage element 404 and generator motor 401 via a power line, and drive wheels 141 with power supplied from one or both of power storage element 404 and generator motor 401. During running acceleration, the running motors 402f and 402r are driven by the running inverters 420f and 420r. The power running torque generated by the power running drive is transmitted to the front wheel 141F and the rear wheel 141R through the propeller shaft 145, the differential devices 143F and 143R and the axles 142F and 142R, and the wheel loader 100 is accelerated. During traveling braking, the regenerative torque (braking torque) generated by the traveling electric motors 402f and 402r is transmitted to the wheels 141 in the same manner as the power running torque, and the wheel loader 100 is decelerated.

  The wheel 141 is braked by a hydraulic brake (not shown). The hydraulic brake obtains a braking force according to a brake pressure from a hydraulic brake control valve (not shown).

  Traveling inverters 420f and 420r drive each of the traveling motors 402f and 402r by supplying AC traveling drive power during traveling acceleration. Traveling inverters 420f and 420r convert the regenerative power (AC power) generated by travel motors 402f and 402r during travel braking into DC power of a predetermined voltage and supply it to power storage element 404. Converter 440, M / G inverter 410, and traveling inverters 420f and 420r are connected to the same power line, and are configured to be able to supply power to each other. Converter 440 monitors a DC voltage (DC voltage) of a smoothing capacitor (not shown) attached to the power line, and controls charging / discharging of power storage element 404 so as to keep the DC voltage of the smoothing capacitor constant.

  In addition, in this Embodiment, although it is set as the structure provided with two traveling motors 402 and two traveling inverters 420, it is not limited to this, It is a structure provided with one traveling motor and one traveling inverter. The number of these is not limited. Hereinafter, for simplification of description, a configuration including one traveling motor 402 and one traveling inverter 420 will be described.

  The main controller 200 and the engine controller 10c each include an arithmetic processing device. Each arithmetic processing unit includes a CPU, ROM and RAM as storage devices, and other peripheral circuits. The main controller 200 controls the entire system including the traveling system and the hydraulic work system of the wheel loader 100, and controls each part so that the entire system exhibits the best performance.

  As shown in FIGS. 3 and 4, the main controller 200 includes pilot pressure sensors 201a, 201b, 202a, 202b (see FIG. 4), a pump pressure sensor 203 (see FIG. 4), and an arm angle sensor 204 (see FIG. 3). ), Forward / reverse selector switch 206 (see FIG. 3), accelerator pedal sensor 207 (see FIG. 3), travel motor speed sensor 208 (see FIG. 3), and brake pedal sensor 209 (see FIG. 3). A signal is input.

  As shown in FIG. 4, the operation amount of the arm operation lever 301 is detected by the pilot pressure sensors 201a and 201b. The pilot pressure sensor 201a outputs a lift-up command corresponding to the lift-up operation amount, and the pilot pressure sensor 201b outputs a lift-down command corresponding to the lift-down operation amount. The operation amount of the bucket operation lever 302 is detected by the pilot pressure sensors 202a and 202b. The pilot pressure sensor 202a outputs a rollback command corresponding to the rollback operation amount, and the pilot pressure sensor 202b outputs a dump command corresponding to the dump operation amount. Note that the lift-up command, lift-down command, rollback command, and dump command will be described as lever signals when collectively referred to.

  The discharge pressure of the main pump 11 (hereinafter simply referred to as pump pressure) is detected by a pump pressure sensor 203. The pump pressure sensor 203 is provided between the main pump 11 and the arm control valve 310, and outputs a pump pressure signal corresponding to the detected pump pressure to the main controller 200.

  As shown in FIG. 3, the depression amount of the accelerator pedal 162 is detected by the accelerator pedal sensor 207. The amount of depression of the brake pedal 163 is detected by a brake pedal sensor 209. The accelerator pedal sensor 207 and the brake pedal sensor 209 output an accelerator signal and a brake signal to the main controller 200 in accordance with the operation amount by the driver, that is, the depression amount, respectively. That the forward / reverse switching lever 161 has been operated forward or backward is detected by the forward / reverse switching switch 206, and the forward / reverse switching switch 206 outputs a forward signal or reverse signal to the main controller 200.

  Traveling motor rotational speed sensor 208 detects the rotational speed of traveling motor 402 and outputs a traveling motor rotational speed signal to main controller 200.

  FIG. 8 is a block diagram illustrating functions of the main controller 200. As shown in FIG. 8, the main controller 200 includes a power storage management unit 210, a hydraulic pressure request calculation unit 220, a travel request calculation unit 230, an output management unit 240, a target rotation number calculation unit 250, and a generator motor control unit. 260, a tilt angle control unit 270, a traveling motor / brake control unit 280, and a brake control unit 290 are functionally provided.

-Power storage management unit-
The power storage management unit 210 calculates the allowable charging power P _{wr_chg_max} of the power storage element 404 and outputs it to the output management unit 240. The storage voltage of the storage element 404 detected by the converter 440 is input to the storage management unit 210. The power storage management unit 210 receives the allowable charging power of the power storage element 404 based on the storage voltage of the power storage element 404 input from the converter 440 and the allowable charging power map stored in a storage device (not shown) in the main controller 200. P _{wr_chg_max} is calculated.

  FIG. 9 shows an example of the allowable charging power map. In FIG. 9, Vcmin and Vcmax are the lowest voltage and the highest voltage in the usage range where the storage element 404 is unlikely to deteriorate. The allowable charging power map is set so that the allowable charging power becomes 0 or less near the maximum voltage Vcmax so that the storage voltage of the storage element 404 does not exceed the maximum voltage Vcmax. On the other hand, Icmax is set based on the maximum current limit of converter 440. The allowable charging power map is also set such that the allowable charging power decreases as the stored voltage decreases so that the charging current does not exceed the maximum current limit Icmax.

-Hydraulic demand calculation part-
The hydraulic pressure request calculation unit 220 calculates a pump required flow rate command q _{pmp_req} and a hydraulic pressure request output P _{wr_pmp_req} . The hydraulic pressure request calculation unit 220 receives lever signals from the arm operation lever 301 and the bucket operation lever 302, and receives a pump pressure signal representing the pump pressure p _pmp from the pump pressure sensor 203. In order to simplify the description, the operation of the steering wheel 303 and the operation of the steering cylinder 130 are not included in the calculation.

  FIG. 10 is a block diagram for explaining the function of the hydraulic pressure request calculation unit 220. The hydraulic pressure request calculation unit 220 functionally includes a work state determination unit 221, a flow rate calculation unit 224, a switching unit 225, a maximum value selection unit 226, an output calculation unit 227, and an arm height determination unit 229. ing.

  The work state determination unit 221 determines whether or not the state of the wheel loader 100 is an excavation work state. FIG. 14 is a diagram for explaining excavation work by the wheel loader 100, and FIG. 15 is a diagram for explaining cargo handling work (loading work on a truck) by the wheel loader 100. Excavation work and cargo handling work by the wheel loader 100 are performed as follows.

-Excavation work-
(1) As shown in FIG. 14, the driver operates the bucket operation lever 302 and the arm operation lever 301 so that the bucket 102 is parallel to the ground at a slight height from the ground. Let's arrange.
(2) The driver depresses the accelerator pedal 162 to move the wheel loader 100 forward toward the natural ground 9 such as earth and sand, thrust the bucket 102 into the natural ground 9, and the arm operating lever 301 and the bucket operating lever 302. To load the earth and sand into the bucket 102.
(3) The driver operates the arm operation lever 301 and the bucket operation lever 302 to raise the arm 101 and gradually rotate the bucket 102 in the backward tilt direction. When the arm 101 is raised to a predetermined excavation end height, the driver operates the arm operation lever 301 and the bucket operation lever 302 to stop raising the arm 101 and simultaneously rotate the bucket 102 in the backward tilt direction. The earth and sand are drawn into the rear side of the bucket 102. Thereby, wheel loader 100 can be made into a conveyance posture.

-Handling work-
(4) After the driver switches the forward / reverse switching lever 161 to the reverse side, the driver operates the accelerator pedal 162 and the steering wheel 303 to move the wheel loader 100 backward and away from the natural ground 9.
(5) As shown in FIGS. 15 (a) and 15 (b), after the driver switches the forward / reverse switching lever 161 to the forward side, the driver operates the accelerator pedal 162 and the steering wheel 303 to move the wheel loader 100. The wheel loader 100 is moved closer to the truck carrying the earth and sand. Note that the driver raises the arm 101 when traveling forward toward the truck. When the wheel loader 100 stops before the truck, if the bucket 102 has risen to the loading height, the scooped earth and sand can be immediately loaded on the truck. Therefore, when the wheel loader 100 moves forward toward the track, it is desirable to obtain an ascending speed that can quickly raise the arm 101.
(6) As shown in FIG. 15 (c), the driver operates the arm operation lever 301 to raise the arm to the loading height, and then operates the bucket operation lever 302 as shown in FIG. 15 (d). Then, the bucket 102 is rotated in the forward tilt direction, that is, dumped, and the earth and sand are discharged to the loading truck.

  In the present embodiment, the conditions used for determining the work state are determined in consideration of the driver's operation during such excavation work and cargo handling work. The work state determination unit 221 illustrated in FIG. 10 determines that the wheel loader 100 is in the excavation work state when all of the following three conditions (i) to (iii) are satisfied, and the condition (i ) To (iii) are not satisfied, it is determined that the wheel loader 100 is in a non-digging work state.

(I) The arm operation lever 301 is operated in the upward operation direction, and a lever signal representing the pilot pressure p equal to or higher than a predetermined value (for example, pa) corresponding to the lift-up operation amount is transmitted from the pilot pressure sensor 201a to the main controller 200. Must be entered.
(Ii) The forward / reverse switching lever 161 is operated forward, and the forward signal from the forward / reverse switching switch 206 is input to the main controller 200.
(Iii) The height from the traveling surface of the arm tip obtained from the angle signal of the arm 101 input from the arm angle sensor 204 to the main controller 200 is less than a predetermined height (for example, about 300 mm which is the transport height). Be.

  The flow rate calculation unit 224 refers to each characteristic of the pump required flow rate map, and calculates the pump required flow rate based on the lever signal output from each pilot pressure sensor 201a, 201b, 202a, 202b.

  FIG. 11 is a diagram illustrating an example of a pump request flow map. The pump required flow map shows characteristics AR1, AR2, AD and BR, BD. These characteristics AR1, AR2, AD and BR, BD are stored in a storage device (not shown) of the main controller 200 in a look-up table format. Each characteristic may be stored as an approximate expression.

  The characteristic AR1 is used when the arm operation lever 301 is operated in the arm raising side operation direction during excavation work. The characteristic AR2 is used when the arm operation lever 301 is operated in the arm raising side operation direction during non-excavation work. The characteristic AD is used when the arm operation lever 301 is operated in the arm lowering operation direction. The characteristic BR is used when the bucket operation lever 302 is operated in the rollback side operation direction. The characteristic BD is used when the bucket operation lever 302 is operated in the dump side operation direction. Each characteristic AR1, AR2, AD and BR, BD are provided independently and have different characteristics. In addition, the magnitude relationship of pilot pressure p1-p5 demonstrated below is p1 <p2 <p3 <p4 <p5.

  Each of the characteristics AR1, AR2, AD and BR, BD, when the pilot pressure p is 0 or more and p1 or less, the pump required flow rate Q increases as the pilot pressure p increases, and the pilot pressure p is p1. The pump required flow rate Q is determined to be Q1. Hereinafter, for convenience of explanation, the rate of increase of the pump required flow rate Q according to the increase of the pilot pressure p is simply referred to as a flow rate increase rate.

As shown in FIG. 12 (a), the characteristic AR1 that determines the pump required flow rate Q in accordance with the operation amount in the arm raising side operation direction during excavation work is such that the pilot pressure p It is determined that the pump required flow rate Q increases with the increase of. The flow rate increase rate when the pilot pressure p is in the range from p4 to p5 is set to be smaller than the flow rate increase rate in the range from p1 to less than p4. In FIG. 12A, as a comparative example of the characteristic AR1, a characteristic AR1 ′ in which the flow rate increase rate is constant in a range where the pilot pressure p is not less than p1 and not more than p5 is indicated by a broken line. Thus, in the characteristic AR1, the flow rate increase rate in the range from p4 to p5 is set smaller than the flow rate increase rate in the range from p1 to less than p4. Therefore, in the present embodiment, for example, the pump required flow rate Q when the pilot pressure p is p5 can be set to Q _a1 which is smaller than the pump required flow rate Q _b1 obtained from the characteristic AR1 ′ of the comparative example. (Q _a1 <Q _b1 ). Thus, during excavation work, a shock that occurs when the arm 101 is suddenly stopped from a state where the arm operation lever 301 is fully operated in the arm raising side operation direction (see the characteristic AR1 in FIG. 12A). Compared to the comparative example (see the characteristic AR1 ′ indicated by the broken line in FIG. 12A), this can be reduced.

As shown in FIG. 12 (b), the characteristic AR2 that determines the pump required flow rate Q according to the operation amount in the arm raising side operation direction during non-excavation work such as cargo handling work has a pilot pressure p of p1 or more and p5 or less. In the range, the pump required flow rate Q is determined to increase as the pilot pressure p increases. The flow rate increase rate in the range where the pilot pressure p is p2 or more and p5 or less is set smaller than the flow rate increase rate in the range of p1 or more and less than p2. In FIG. 12B, as a comparative example of the characteristic AR2, a characteristic AR2 ′ in which the flow rate increase rate is constant in a range where the pilot pressure p is not less than p1 and not more than p5 is indicated by a broken line. Thus, in the characteristic AR2, the flow rate increase rate in the range from p2 to p5 is set smaller than the flow rate increase rate in the range from p1 to less than p2. Therefore, in the present embodiment, for example, the pump required flow rate Q when the pilot pressure p is p5 can be set to Q _a2 that is smaller than the pump required flow rate Q _b2 obtained from the characteristic AR2 ′ of the comparative example. (Q _a2 <Q _b2 ). Thereby, during non-excavation work, a shock that occurs when the arm 101 is suddenly stopped from a state where the arm operation lever 301 is fully operated in the arm raising side operation direction (see the characteristic AR2 in FIG. 12B). Can be reduced compared to the comparative example (characteristic AR2 ′ indicated by a broken line in FIG. 12B).

As shown in FIGS. 12A and 12B, the average flow rate increase rate in the range where the pilot pressure p is not less than p1 and not more than p5 is set so that the characteristic AR1 is smaller than the characteristic AR2. . Therefore, as shown in FIG. 12 (a), in the range pilot pressure p is p1 or more p5 or less, the pump required flow rate Q _W1 corresponding to the pilot pressure pw representing a predetermined lift-up manipulation amount during excavation work, smaller than the pump required flow _{Q W2} in accordance with the pilot pressure pw representing said predetermined lift-up operation amount in the non-excavation work _{(Q W1 <Q} W2). In this way, it is possible to give priority to the traction force during excavation work by reducing the average flow rate increase rate of characteristic AR1 during excavation work compared to the average flow increase rate of characteristic AR2 during non-excavation work. it can.

  As shown in FIG. 13 (a), the characteristic AD indicates that in the range where the pilot pressure p is not less than p1 and less than p3, the required pump flow rate Q increases as the pilot pressure p increases, and the pilot pressure p is not less than p3 and not more than p5 In this range, the required pump flow rate Q is determined to decrease as the pilot pressure p increases. When the arm 101 is lifted down, the weight of the arm 101 can be used. For this reason, at the time of lift-down, the pump discharge amount may be smaller than that at the time of lift-up in non-excavation work. In the present embodiment, in the range where the pilot pressure p is not less than p1 and not more than p5, the required pump flow rate Q corresponding to the pilot pressure p is smaller in the characteristic AD than in the characteristic AR2.

For example, when the arm operation lever 301 is operated alone during a cargo handling operation, the required pump flow rate Q _XD when the pilot pressure px representing the predetermined lift-down operation amount is detected by the pilot pressure sensor 201b is the predetermined lift The pilot pressure px representing the lift-up operation amount equivalent to the down operation amount is smaller than the pump request flow rate Q _XR when the pilot pressure sensor 201a detects the pilot pressure px. Thus, the arm 101 is lifted by determining the characteristic AD so that the pump required flow rate during the lift-down operation during non-excavation work is smaller than the pump request flow rate during the lift-up operation during non-excavation work. Loss of energy when going down can be suppressed. In the present embodiment, the characteristic AD of the pump required flow rate during the lift-down operation is the same as that during excavation work.

  In work performed in a state where the arm control valve 310 is switched to the float down position (F) (see FIG. 4), for example, leveling work, the discharge amount of the main pump 11 may be small. Therefore, in the characteristic AD, when the pilot pressure p is p3, the pump required flow rate Q is set to the maximum value Q2, and when the pilot pressure p is in the range of p3 or more, the pump required flow rate Q is decreased according to the increase of the pilot pressure p. The pump required flow rate Q at the pilot pressure p5 generated at the float operation position (F) is set to Q1 smaller than Q2. Thereby, the energy loss at the time of leveling work etc. can be suppressed.

  As shown in FIG. 13B, the characteristic BR and the characteristic BD are determined such that the required pump flow rate Q increases as the pilot pressure p increases in the range where the pilot pressure p is not less than p1 and not more than p5. Yes. The characteristic BR and the characteristic BD are common characteristics when the pilot pressure p is in the range of p1 or more and less than p4.

In the characteristic BR, the flow rate increase rate when the pilot pressure p is in the range from p4 to p5 is set smaller than the flow rate increase rate in the range from p1 to less than p4. On the other hand, in the characteristic BD, the flow rate increase rate when the pilot pressure p is in the range from p4 to p5 is set to be the same as the flow rate increase rate in the range from p1 to less than p4. In other words, the flow rate increase rate in the range where the pilot pressure p is not less than p4 and not more than p5 is larger in the characteristic BD than in the characteristic BR. Accordingly, as shown in FIG. 13 (b), in the range pilot pressure p is p4 or p5 below, the pump required flow rate Q _YD is in accordance with the pilot pressure py representing a predetermined dumping operation amount, the predetermined dump operation amount Becomes larger than the required flow rate Q _YR of the pump corresponding to the pilot pressure py representing the rollback operation amount equivalent to (Q _YD > Q _YR ).

  By determining the characteristic BR as described above, when the bucket 102 is suddenly stopped from the state where the bucket operation lever 302 is fully operated in the rollback side operation direction, for example, when the bucket 102 is rotated to the last tilt position. Can reduce the shock that occurs. Further, by setting the characteristic BD as described above, when the earth and sand are loaded on the truck, when the bucket operation lever 302 is fully operated in the dump side operation direction and the bucket 102 is rotated to the most forward tilt position, A moderate shock can be generated intentionally, and the earth and sand can be efficiently removed from the bucket 102.

As shown in FIG. 13B, the average flow rate increase rate in the range where the pilot pressure p is not less than p1 and not more than p5 is such that the characteristics BR and BD are smaller than the characteristics AR2. Therefore, when the pilot pressure p is in the range from p1 to p5, the pump request flow rate Q _ZB corresponding to the pilot pressure pz representing the predetermined rollback operation amount and the dump operation amount is equal to the predetermined rollback operation amount and the dump operation. This is smaller than the required pump flow rate Q _Z2 corresponding to the pilot pressure pz representing the lift-up operation amount during non-digging work, which is equivalent to the amount (Q _ZB <Q _Z2 ). In the excavation work, the operation of the bucket operation lever 302 is also performed simultaneously with the operation of the arm operation lever 301 in the operation direction on the arm raising side. For this reason, by reducing the average flow rate increase rate of the characteristics BR and BD during the bucket operation compared to the average flow rate increase rate of the characteristic AR2 during the lift-up operation during non-excavation work, Traction can be prioritized.

  When the lift-up operation of the arm 101 and the operation of the bucket 102 are combined, the pump request calculated by referring to the characteristic AR1 and the characteristic BR or BD by the maximum value selection unit 226 (see FIG. 10) described later. The larger one of the flow rates Q is selected. Therefore, as shown in FIG. 13 (b), the average flow rate increase rate in the range where the pilot pressure p is not less than p1 and not more than p5 is larger in the characteristics BR and BD than in the characteristic AR1. As a result, it is possible to suppress a decrease in the ascending speed of the arm 101 due to a decrease in the flow rate supplied to the arm cylinder 110 during the combined operation of the arm 101 and the bucket 102 as compared to when the arm 101 operates alone.

  As shown in FIG. 10, when the work state determination unit 221 determines that the excavation work state is present, the switching unit 225 switches to the terminal a side. For this reason, when the wheel loader 100 is in an excavation work state, the pump request flow rate Q calculated based on the pilot pressure p detected by the pilot pressure sensor 201a is output to the maximum value selection unit 226 with reference to the characteristic AR1. . On the other hand, when the work state determination unit 221 determines that it is in the non-digging work state, the switching unit 225 switches to the terminal b side. For this reason, when the wheel loader 100 is in a non-excavation work state, the pump request flow rate Q calculated based on the pilot pressure p detected by the pilot pressure sensor 201a is output to the maximum value selection unit 226 with reference to the characteristic AR2. The

The maximum value selection unit 226 selects the largest value among the pump request flow rates Q corresponding to the respective characteristics calculated by the flow rate calculation unit 224, stores the value as the pump request flow rate command _{qpmp_req} , and outputs the calculation. Output to the unit 227 and the tilt angle control unit 270.

Output calculation unit 227, by using the pump required flow command _{q Pmp_req,} and a pump pressure _{p pmp} received, it calculates the oil pressure required output _{P Wr_pmp_req} by the following equation (1). The calculated hydraulic pressure request output is output to the tilt angle control unit 270.
_{P wr_pmp_req = q pmp_req · p pmp} ... (1)
In order to simplify the explanation, the efficiency of the main pump 11 is not considered, and the efficiency of the main pump 11 is not included in the following calculation formulas as well.

-Travel request calculator-
The travel request calculation unit 230 _generates a travel request torque T _{rq_req} that is a torque required for the travel motor 402 during travel and a travel request output P _{wr_drv_req} that is power consumed or generated (regenerated) by the travel motor 402 during travel. Calculate. The travel request calculation unit 230 performs a calculation using an accelerator request torque map stored in a storage device (not shown) of the main controller 200.

FIG. 16 shows an example of the accelerator required torque map. The accelerator required torque map is set so that the accelerator required torque T _{rq_acc} is in inverse proportion to the absolute value of the rotational speed of the traveling motor 402 while being proportional to the accelerator signal for the maximum torque curve of the traveling motor 402. The travel request calculation unit 230 uses the accelerator request torque map based on the accelerator signal input from the accelerator pedal sensor 207 and the travel motor rotation speed N _mot input from the travel motor rotation speed sensor 208, using the accelerator request torque map. T _{rq_acc} is calculated.

The travel request calculation unit 230 calculates the calculated accelerator request torque T _{rq_acc} , the forward / reverse switch signal V _FNR input from the forward / reverse switch 206, and the travel motor speed N _mot input from the travel motor speed sensor 208. , by using the brake signal _{V brk} input from the brake pedal sensor 209, and calculates the travel required torque _{T Rq_req} by the following equation (2).
T _{rq_req} = sign (V _FNR ) · T _{rq_acc} −sign (N _mot ) · K _brk · V _brk
... (2)
However, sign is a sign function, and returns 1 when the argument is positive, “−1” when it is negative, and “0” when it is 0. Further, the forward / reverse switch signal _VFNR indicates “1” when the forward / reverse selector switch 206 is in the forward direction, “−1” when it is in the reverse direction, and “0” when it is neutral. _Kbrk is a proportionality constant, and is set in advance so that deceleration without excess or deficiency can be obtained by operating the brake pedal.

DC voltage V _DC detected by converter 440 and a traveling DC current detected by traveling inverter 420 (hereinafter referred to as traveling DC current _{IDC_mot} ) are input to traveling request calculation unit 230. The traveling DC current is a DC current that flows on the power line side of the traveling inverter 420, with the consumption side being positive and the regeneration side being negative. The travel request calculation unit 230 calculates the travel request output P _{wr_drv_req} by the following equation (3) using the DC voltage V _DC and the travel DC current I _{DC_mot} .
P _{wr_drv_req} = V _DC · I _{DC_mot} (3)

-Output management section-
The output management unit 240 _calculates a tilt angle increase command dD _{pmp_t} , a regenerative power reduction command dP _{wr_mot_t} , a power generation output command P _{wr_gen_t,} and an engine output command P _{wr_eng_t} . The output management unit 240 includes an engine speed N _eng from the engine controller 10c, an allowable charging power P _{wr_chg_max} from the power storage management unit 210, a hydraulic pressure request output P _{wr_pmp_req} from the hydraulic pressure calculation unit 220, and a travel request calculation unit. The travel request output P _{wr_drv_req} from 230 is input.
The output management unit 240 receives the engine speed and uses it for calculation. However, since the engine 10, the generator motor 401, and the main pump 11 are mechanically connected, the generator motor is used instead of the engine speed. 401 and the rotation speed of the main pump 11 may be appropriately received via a sensor or the like and used for calculation.

(Surplus power)
The output management unit 240 receives the travel request output P _{wr_drv_req} from the travel request calculation unit 230. If the travel request output P _{wr_drv_req} is 0 or more, the output management unit 240 determines that the wheel loader 100 is in a power running operation. If the travel request output P _{wr_drv_req} is negative, the output management unit 240 determines that the wheel loader 100 is in a regenerative operation. When the wheel loader 100 determines that the regenerative operation is being performed, the output management unit 240 uses the allowable charging power P _{wr_chg_max} from the power storage management unit 210 and the travel request output P _{wr_drv_req} from the travel request calculation unit 230 to obtain the following equation: The surplus power P _{wr_sup} is calculated from (4).
P _{wr_sup} = max (| P _{wr_drv_req} | −P _{wr_chg_max} , 0) (4)

When the travel request output P _{wr_drv_req} during regeneration is larger than the allowable charging power P _{wr_chg_max} , the difference is calculated as surplus power P _{wr_sup} . When the travel request output P _{wr_drv_req} at the time of regeneration is smaller than the allowable charging power P _{wr_chg_max} , the difference is negative and the surplus power P _{wr_sup} is calculated as 0. In this case, the power storage element 404 can be charged with regenerative power.

The output management unit 240 monitors whether or not the calculated surplus power P _{wr_sup} is 0, so that all the regenerative power generated in the traveling motor 402 can be charged in the power storage element 404, that is, the surplus power P _{wr_sup} is It is determined whether or not it occurs. However, when it is determined that the power running is in _progress , the surplus power P _{wr_sup} is set to zero.
That is, the output management unit 240 can determine the following from the surplus power P _{wr_sup} calculated by Expression (4).
(A) When the surplus power P _{wr_sup} is 0, the power storage element 404 can be charged with regenerative power. (B) When the surplus power P _{wr_sup} is not 0, the regenerative power cannot be used to charge the storage element 404, so that the regenerative power is consumed by driving the generator motor 401 in the electric mode.

(Mode judgment based on engine speed)
When the output management unit 240 determines that the wheel loader 100 is in the regenerative operation, the output management unit 240 determines whether the engine speed N _eng of the engine 10 is equal to or less than the first set threshold N _{eng — th1} and further to the second set threshold N _{eng — th2.} To do. Here, the first set threshold value N _{eng_th1} and the second set threshold value N _{eng_th2} are “idle engine speed of engine 10 <first set threshold value N _{eng_th1} <second set threshold value N _{eng_th2} <min {maximum engine speed of engine 10, main Is set so as to satisfy the "maximum rotational speed of the pump 11}". The first setting threshold N _{eng — th1} and the second setting threshold N _{eng — th2} are stored in a storage device (not shown) of the main controller 200, and can be reset as appropriate.

The output management unit 240 _compares the input engine speed N _eng , the first set threshold value N _{eng — th1} and the second set threshold value N _{eng — th2,} and determines whether the engine 10 is in the low speed mode, the rotation suppression mode, or the high speed mode. Determine whether. In this case, if the engine speed N _eng is equal to or less than the first set threshold value N _{eng — th1} , the output management unit 240 determines that the engine 10 is in the low speed mode. If the second set threshold value _{N Eng_th2} less larger than the engine rotational speed _{N eng} is first set threshold value _{N eng_th1,} output management unit 240 determines the engine 10 and the rotation suppression mode. When the engine speed N _eng is larger than the second setting threshold N _{eng — th2} , the output management unit 240 determines that the engine 10 is in the high speed mode.

When it is determined that the wheel loader 100 is in a power running operation, the output management unit 240 determines that the engine 10 is in the normal mode regardless of the magnitude of the engine speed N _eng .

(Hydraulic cylinder operation judgment)
The output management unit 240 determines which of the steering cylinder 130, the arm cylinder 110, and the bucket cylinder 120 is operating based on the hydraulic pressure request output _{Pwr_pmp_req} calculated by the hydraulic pressure request calculation unit 220. If the required hydraulic pressure output P _{wr_pmp_req} is equal to or larger than a set value calculated by, for example, pump pressure × minimum discharge amount, the output management unit 240 is operating at least one of the steering cylinder 130, the arm cylinder 110, and the bucket cylinder 120. Is determined.

(Tilt angle increase command)
The output management unit 240 increases the tilt angle command for increasing the tilt angle of the swash plate 11a of the main pump 11 when any of the following three conditions (i) to (iii) is satisfied. dD _{pmp_t} is calculated according to the following equation (5). When any of the conditions (i) to (iii) is not satisfied, the output management unit 240 sets the tilt angle increase command dD _{pmp_t} to 0.
(I) The wheel loader 100 is determined to be in regenerative operation.
(Ii) It is determined that none of the steering cylinder 130, the arm cylinder 110, and the bucket cylinder 120 is in operation when the generator motor 401 is driven by surplus power of the traveling motor 402.
(Iii) It is determined that the engine 10 is in the rotation suppression mode or the high rotation mode.

Output management unit 240 calculates the engine speed _{N eng} input from the engine controller 10c, by using the first set threshold value _{N Eng_th1,} the tilt angle increase instruction _{dD Pmp_t} by the following equation (5).
dD _{pmp_t} = max {K _nD (N _eng −N _{eng — th1} ), 0} (5)
_{However, K nD} is a proportional constant for calculating the increase instruction tilting angle from the difference between the first set threshold value _{N Eng_th1} and the engine speed _{N eng,} it is previously stored in the main controller 200.

If the tilting angle increases command _{dD Pmp_t} is calculated based on the equation (5), as the engine rotational speed _{N eng} is increased tilt angle increase instruction _{dD Pmp_t} increases, the discharge capacity of the main pump 11 is increased . As a result, the load torque of the main pump 11, that is, the regenerative braking force can be increased as the engine speed N _eng increases.

(Regenerative power reduction directive)
The output management unit 240 reduces the regenerative power for reducing the regenerative torque generated by the traveling motor 402 when the generator motor 401 is driven by the surplus power of the traveling motor 402 and the engine 10 is determined to be in the high rotation mode. A command dP _{wr_mot_t} is calculated. The output management unit 240 calculates the regenerative power reduction command dP _{wr_mot_t} according to the following equation (6) using the engine speed N _eng input from the engine controller 10c and the second setting threshold N _{eng_th2} .
dP _{wr_mot_t} = max {K _nP (N _eng −N _{eng — th 2} ), 0} (6)
In Equation (6), K _nP is a proportional constant for calculating a regenerative power reduction command from the difference between the second set threshold value N _{eng — th2} and the engine speed N _eng .
When the engine 10 is in one of the normal mode, the low rotation mode, and the rotation suppression mode, the output management unit 240 sets the regenerative power reduction command dP _{wr_mot_t} to 0.

If regenerative power reduction instruction _{dP Wr_mot_t} based on the above equation (6) is calculated as the engine rotational speed _{N eng} is increased, the regenerative power reduction command _{dP Wr_mot_t} increases, the regenerative power of the travel motor 402 is reduced. As a result, the regenerative power consumed by the generator motor 401 can be reduced as the engine speed N _eng increases.
This regenerative power reduction command control is performed when the rotational speed of the engine 10 is traveling in a high speed range, for example, when the accelerator pedal 162 is released and the wheel loader 100 enters a regenerative operation, the traveling motor 402 is also used. It is operated in a high speed range and is performed to prevent the power generation amount from becoming too large.

(power consumption)
When it is determined that the wheel loader 100 is in the regenerative operation, the output management unit 240 calculates power consumption P _{wr_cns} that is power that should be consumed by the generator motor 401 among the regenerative power generated by the traveling motor 402. The output management unit 240 calculates the power consumption P _{wr_cns} from the following equation (7) using the calculated surplus power P _{wr_sup} and the calculated regenerative power reduction command dP _{wr_mot_t} .
_{P wr_cns = max (P wr_sup -dP} wr_mot_t, 0) ... (7)
However, the output management unit 240 sets the power consumption P _{wr_cns} to 0 when the wheel loader 100 determines that the power running is in _progress .

When the power consumption P _{wr_cns} is calculated using the above equation (7), the output management unit 240 uses the following equation (8) to generate the power generation output command P based on the travel request output P _{wr_drv_req} and the power consumption P _{wr_cns. wr_gen_t} is calculated.
_{Pwr_gen_t} = max ( _{Pwr_drv_req} , 0) _{−Pwr_cns} (8)

The output management unit 240 calculates the engine output command P _{wr_eng_t} by the following equation (9) using the hydraulic pressure request output P _{wr_pmp_req} from the hydraulic pressure request calculation unit 220 and the calculated power generation output command P _{wr_gen_t} .
_{Pwr_eng_t} = _{Pwr_pmp_req} + _{Pwr_gen_t} (9)

-Target speed calculation unit-
The target rotational speed calculation unit 250 calculates an engine rotational speed command N _{eng — t} to be output to the engine controller 10 c. Based on the engine output command P _{wr_eng_t} calculated by the output management unit 240, the target rotational speed calculation unit 250 calculates an operating point at which the engine efficiency is highest using a fuel consumption map such as an engine. The target rotational speed calculation unit 250 sets the engine rotational speed at the calculated operating point as the engine rotational speed command N _{eng — t} . _Upon receiving the engine speed command N _{eng_t} from the target speed calculation unit 250, the engine controller 10c rotates the engine 10 at the engine speed indicated by the engine speed command N _{eng_t} .

-Generator motor control section-
The generator motor control unit 260 calculates the generator motor torque command T _{rq_gen_t} and outputs the generator motor torque command T _{rq_gen_t} to the M / G inverter 410 to control the drive of the generator motor 401. The generator motor control unit 260 receives the engine speed N _eng from the engine controller 10 c, the power generation output command P _{wr_gen_t} from the output management unit 240, and the engine speed command N _{eng_t} from the target speed calculation unit 250. Is done. The generator motor control unit 260 calculates the generator motor torque command T _{rq_gen_t} by the following formula (10) using the engine speed N _eng , the power generation output command P _{wr_gen_t,} and the engine speed command N _{eng_t} . The generator motor control unit 260 outputs the calculated generator motor torque command T _{rq_gen_t} to the M / G inverter 410. The sign of the power generation output command P _{wr_gen_t} indicates positive power generation of the generator motor 401, and negative indicates power running of the generator motor 401.
T _{rq_gen_t} = max {K _p (N _{eng — t} −N _eng ), 0} −P _{wr — gen — t} / N _eng
(10)
However, _{K p} is the proportional constant for calculating the generator motor torque from the difference between the engine speed _{N eng} and the engine rotational speed command _{N eng_t.}

-Tilt angle control unit-
The tilt angle control unit 270 calculates a tilt angle control signal V _{Dp_t} and drives a tilt angle control valve (not shown) of the pump regulator 211 of the main pump 11 based on the tilt angle control signal. Thus, the tilt angle of the swash plate 11a of the main pump 11, that is, the capacity is controlled. The tilt angle control unit 270 receives the engine speed N _eng from the engine controller 10c, the pump request flow rate command q _{pmp_req} from the hydraulic pressure request calculation unit 220, and the tilt angle increase command dD _{pmp_t} from the output management unit 240. By using the following equation (11), the tilt angle control signal V _{Dp_t} is calculated.
V _{Dp_t} = K _Dp {(q _{pmp_req} / N _eng ) + dD _{pmp_t} } (11)
K _Dp is a proportional constant for calculating a tilt control signal necessary for setting the tilt angle of the main pump 11 as a target value.

When the tilt angle increase command dD _{pmp_t} is 0, the actual pump discharge amount is maintained at the pump request flow rate (see FIG. 10) calculated according to the operation amount of the arm operation lever 301 and the bucket operation lever 302. A tilt angle control signal V _{Dp_t} is set. Therefore, the tilt angle of the main pump 11 is the rotational speed of the engine 10, the generator motor 401 or the main pump 11 so that the discharge amount of the main pump 11 is maintained at a value required by the driver (pump required flow rate). It is controlled so as to become smaller as it increases.

-Driving motor / brake control unit-
Traveling motor and brake control unit 280 calculates the traveling motor torque command _{T Rq_mot_t,} by outputting the calculated traveling motor torque command _{T Rq_mot_t} to the traveling inverter 420 to control the power running, regeneration of the traveling motor 402. The travel motor / brake control unit 280 includes a travel request torque T _{rq_req} from the travel request calculation unit 230, a travel motor rotational speed N _mot from the travel motor rotational speed sensor 208, and a regenerative power reduction command from the output management unit 240. dP _{wr_mot_t} is input. The travel motor / brake control unit 280 calculates the travel motor torque command T _{rq_mot_t} by the following equation (12) using the travel request torque T _{rq_req} , the travel motor rotation speed N _mot, and the regenerative power reduction command dP _{wr_mot_t.} To do.
T _{rq_mot_t} = sign (T _{rq_req} ) · max {| T _{rq_req} | − (dP _{wr_mot_t} ) / | N _mot |, 0} (12)

The travel motor / brake control unit 280 uses the calculated travel motor torque command T _{rq_mot_t} , travel request torque T _{rq_req} , and travel motor rotation speed N _mot to calculate the braking torque command T _{rq_brk_t according} to the following equation (13). calculate. When the braking torque command T _{rq_brk_t} is calculated, the absolute value of the traveling motor torque command T _{rq_mot_t} decreases as the regenerative power reduction command dP _{wr_mot_t} increases, and the braking torque command T _{rq_brk_t} increases by this decrease.
T _{rq_brk_t} = max {-sign (N _mot ) · (T _{rq_req} −T _{rq_mot_t} ), 0}
... (13)

−Brake control unit−
The brake control unit 290 calculates a brake control signal V _{Brk_t,} controls the hydraulic brake (not shown) by driving the hydraulic brake control valve (not shown) based on the brake control signal _V brk_t. The brake control unit 290 is based on the braking torque command T _{rq_brk_t} calculated by the traveling motor / brake control unit 280. A brake control signal _{Vbrk_t} is calculated using the following equation (14) to drive a hydraulic brake control valve (not shown).
_{V brk_t = K brk · T rq_brk_t} ... (14)
However, K _brk is preset proportional constant such that the actual braking torque of the braking torque command T _{Rq_brk_t} and hydraulic brakes are matched.

-Main controller processing-
Hereinafter, processing performed by the main controller 200 will be described together with an example of main operations during excavation work and cargo handling work. As shown in FIG. 14, the wheel loader 100 is moved forward toward the natural ground 9, the bucket 102 is pushed into the natural ground 9, the arm operating lever 301 and the bucket operating lever 302 are operated, and the earth and sand are moved into the bucket 102. Load it on. At this time, three conditions for determining the excavation work state, that is, (i) the arm operation lever 301 is operated in the upward operation direction, and (ii) the forward / reverse switching lever 161 is operated in the forward direction. (Iii) The height of the arm 101 is less than the predetermined height. For this reason, the work state determination unit 221 illustrated in FIG. 10 determines that the wheel loader 100 is in the excavation work state.

During excavation work, when the driver operates the arm operating lever 301 alone in the arm raising side operating direction among the arm operating lever 301 and the bucket operating lever 302, the flow rate calculation unit 224 refers to the characteristic AR1 and lifts up. The pump request flow rate Q calculated based on the manipulated _variable is output to the tilt angle control unit 270 as a pump request flow rate command q _{pmp_req} .

During excavation work, when the driver operates the arm control lever 301 or the bucket operation lever 302 alone in the rollback side operation direction, the flow rate calculation unit 224 refers to the characteristic BR and rolls back. The pump request flow rate Q calculated based on the manipulated _variable is output to the tilt angle control unit 270 as a pump request flow rate command q _{pmp_req} .

During excavation work, when the driver operates the arm operation lever 301 in the arm raising side operation direction and at the same time the bucket operation lever 302 is operated in the rollback side operation direction, based on each of the characteristics AR1 and the characteristics BR. The larger one of the calculated pump request flow rates Q is selected by the maximum value selection unit 226, and the selected pump request flow rate Q is output to the tilt angle control unit 270 as a pump request flow rate command q _{pmp_req} .

  The driver temporarily moves the wheel loader 100 backward and travels forward toward the truck. The driver lifts up the arm 101 while moving the wheel loader 100 forward. When the height of the arm 101 is equal to or higher than the predetermined height, the work state determination unit 221 determines that the wheel loader 100 is in a non-excavation work state.

If the driver operates the arm operation lever 301 alone in the arm raising side operation direction among the arm operation lever 301 and the bucket operation lever 302 during forward traveling toward the truck, the flow rate calculation unit 224 refers to the characteristic AR2. Then, the requested pump flow rate Q calculated based on the lift-up operation amount is output to the tilt angle control unit 270 as the requested pump flow rate command q _{pmp_req} .

The driver operates the arm operation lever 301 to raise the bucket 102 to the loading height. Thereafter, when the driver operates the bucket operation lever 302 alone in the dump side operation direction of the arm operation lever 301 or the bucket operation lever 302, the flow rate calculation unit 224 refers to the characteristic BD and determines the dump operation amount. The requested pump flow rate Q calculated based on this is output to the tilt angle control unit 270 as the requested pump flow rate command q _{pmp_req} .

When the driver operates the arm operation lever 301 alone in the arm lowering operation direction among the arm operation lever 301 and the bucket operation lever 302, the flow rate calculation unit 224 refers to the characteristic AD and sets the lift-down operation amount. The requested pump flow rate Q calculated based on this is output to the tilt angle control unit 270 as the requested pump flow rate command q _{pmp_req} .

According to this Embodiment described above, there can exist the following effects.
(1) The discharge amount of the main pump 11 is controlled by the main controller 200 and the pump regulator 211 in accordance with the operation direction and operation amount of the arm operation lever 301 detected by the pilot pressure sensors 201a and 201b. Accordingly, an appropriate pump discharge amount corresponding to the operation of the arm 101 can be supplied to the arm cylinder 110, and the main pump 11 can be operated efficiently. For example, since the arm 101 can be rotated downward by utilizing its own weight acting on the arm 101 at the time of lift-down, a desired speed can be obtained even if the discharge amount of the main pump 11 is small. For this reason, as shown in FIG. 13A, when a predetermined lift-down operation amount (for example, pilot pressure p = px) is detected, a lift-up operation amount (pilot) equivalent to the predetermined lift-down operation amount is detected. By reducing the discharge amount of the main pump 11 compared to when the pressure (p = px) is detected, the energy loss at the time of lift-down can be reduced.

(2) As shown in FIG. 11, characteristics BR and BD of the discharge amount of the main pump 11 according to the operation direction and operation amount of the bucket operation lever 302 when the bucket operation lever 302 is operated alone, and the arm operation The discharge amount characteristics AR1, AR2, and AD of the main pump 11 corresponding to the operation direction and operation amount of the arm operation lever 301 when the lever 301 is operated independently are provided individually so that each has different characteristics. did. By providing characteristics corresponding to the operation of the bucket 102 as well as the arm 101, the main pump 11 can be operated more efficiently.

(3) The operation state of the wheel loader 100 is detected, and the operation amount in the arm raising side operation direction in which the arm 101 is rotated to raise the bucket 102 according to the operation state, that is, the main amount corresponding to the lift-up operation amount. The discharge amount of the pump 11 was changed. In the present embodiment, when the excavation work state is detected by the main controller 200, the discharge amount of the main pump 11 corresponding to the lift-up operation amount is smaller than when the excavation work state is not detected. AR1 and characteristic AR2 were defined. As a result, the traveling load, that is, the traction force can be prioritized over the work load during excavation work, and the arm 101 can be quickly raised during the cargo handling work during non-excavation work. As a result, the efficiency of excavation work and cargo handling work can be improved.

  Conventionally, if the rotational speed of the arm 101 upward during excavation work is too high, the bucket 102 may rise before the bucket 102 sufficiently penetrates the earth and sand that is the object to be excavated, and the amount of excavation may be reduced. On the other hand, if the rotation speed of the arm 101 is too low during excavation work, the bucket 102 bites into the earth too much and the work load increases, and the arm 101 cannot be rotated upward, or the wheel slips. (Idle). In contrast, in the present embodiment, the discharge amount of the main pump 11 during excavation work is reduced as compared with that during non-excavation work such as cargo handling work. During excavation work, the discharge amount of the main pump 11 is ensured such that the bucket 102 does not bite into the earth and sand. As a result, a high traction force can be generated while appropriately generating a turning force upward of the arm 101, so that excavation work can be performed efficiently.

  In the present embodiment, the characteristics BR and BD are characteristics in which the required pump flow rate Q corresponding to the operation amount is smaller than the characteristics AR2, and are characteristics closer to the characteristics AR1 than the characteristics AR2. . For this reason, priority can be given to traction force even when the rollback operation of the bucket 102 and the lift-up operation of the arm 101 are performed in combination during excavation work.

  On the other hand, in the cargo handling operation, the arm 101 is raised while the wheel loader 100 is moved forward (see FIG. 15). When the distance from the natural ground 9 to the track is short, it is desirable to raise the arm 101 to the loading height as quickly as possible. In the present embodiment, since the discharge amount of the main pump 11 at the time of unloading work during unloading work is increased as compared with at the time of excavation work, the bucket 102 can be quickly raised. For this reason, cargo handling work can be performed efficiently.

(4) As shown in FIG. 12B, the increase rate of the discharge amount of the main pump 11 according to the increase in the lift-up operation amount when the pilot pressure p representing the lift-up operation amount is equal to or higher than p2 is the lift-up. The characteristic AR2 is determined to be smaller than the increase rate of the discharge amount of the main pump 11 according to the increase of the lift-up operation amount when the pilot pressure p representing the operation amount is not less than p1 and less than p2. Similarly, as shown in FIG. 12A, the increase rate of the discharge amount of the main pump 11 according to the increase in the lift-up operation amount when the pilot pressure p representing the lift-up operation amount is equal to or higher than p4 is the lift-up. The characteristic AR1 is determined to be smaller than the increase rate of the discharge amount of the main pump 11 according to the increase of the lift-up operation amount when the pilot pressure p representing the operation amount is not less than p1 and less than p4. Thus, during excavation work, a shock that occurs when the arm 101 is suddenly stopped from a state where the arm operation lever 301 is fully operated in the arm raising side operation direction (see the characteristic AR1 in FIG. 12A). This can be reduced compared to the comparative example (see characteristic AR1 ′ in FIG. 12A) in which the flow rate increase rate is constant in the range of p1 to p5. Similarly, a shock that occurs when the arm 101 is suddenly stopped in a state where the arm operation lever 301 is fully operated in the arm raising side operation direction during non-excavation work (see the characteristic AR2 in FIG. 12B). Can be reduced compared to the comparative example (see characteristic AR2 ′ in FIG. 12B) in which the flow rate increase rate is constant in the range of p1 to p5. For this reason, for example, when the arm 101 is suddenly stopped after the arm operation lever 301 is fully operated, it is possible to prevent the earth and sand loaded in the bucket 102 from falling down.

(5) As shown in FIG. 13B, when a predetermined dump operation amount (for example, pilot pressure p = py) is detected when the pilot pressure p representing the dump operation amount is p4 or more, The characteristics BD and the characteristics BR are determined so that the discharge amount of the main pump 11 becomes larger than when a rollback operation amount (pilot pressure p = py) equivalent to the dump operation amount is detected. Thereby, for example, when the bucket 102 is suddenly stopped from the state where the bucket operation lever 302 is fully operated in the rollback side operation direction (see the characteristic BR in FIG. 13B) during excavation work, As compared with the case where the characteristic BD is used at the time of the rollback operation, it is possible to prevent the earth and sand loaded in the bucket 102 from falling down. On the other hand, for example, when the bucket 102 is suddenly stopped from the state in which the bucket operation lever 302 is fully operated in the dumping operation direction during the loading operation (see the characteristic BD in FIG. 13B), an intentionally moderate shock Can be generated, and the earth and sand can be efficiently removed from the bucket 102.

  As shown in FIG. 4, the arm control valve 310 includes a power down position (D) for supplying the pressure oil to the rod side oil chamber 110 b with the bottom side oil chamber 110 a of the arm cylinder 110 as a tank pressure, and the arm cylinder 110. The bottom-side oil chamber 110a and the rod-side oil chamber 110b each have a float-down position (F) in which the tank pressure is set to the tank pressure, and from the power-down position (D) to the float-down position (F ). As shown in FIG. 13A, when the pilot pressure p representing the lift-down operation amount is 0 or more and less than p3, the discharge amount of the main pump 11 is increased according to the increase in the lift-down operation amount, and the lift-down operation amount is represented. When the pilot pressure p is equal to or higher than p3, the characteristic AD is set so that the discharge amount of the main pump 11 is decreased as the lift-down operation amount is increased. Thereby, the energy loss at the time of leveling work etc. can be suppressed.

The following modifications are also within the scope of the present invention, and one or a plurality of modifications can be combined with the above-described embodiment.
(1) The determination method of whether it is a digging work state is not limited to the above-described embodiment.
(1-1) For example, when the pump pressure is equal to or higher than a predetermined value, the engine speed is equal to or higher than the predetermined value, and the traveling motor speed is lower than a predetermined value. It may be determined that it is in the excavation work state, and if any one of them is not satisfied, it may be determined that it is in the non-excavation work state.
(1-2) For example, the pump pressure is not less than a predetermined value, the current supplied to the traveling motor is not less than the predetermined value, and the traveling motor rotational speed is less than the predetermined value. It may be determined that it is in the excavation work state when it is being performed, and it may be determined that it is in the non-excavation work state when any one is not satisfied.
(1-3) For example, when the mode switch for performing excavation work is turned on, it may be determined that the excavation work state is present.

(2) In the above-described embodiment, it is determined whether or not the working state of the wheel loader 100 is the excavation working state, but the present invention is not limited to this. For example, an angle sensor mounted on the vehicle body is used to determine whether the vehicle is in a loading operation state or whether the wheel loader 100 is in a so-called lifting operation state in which earth and sand in the bucket 102 are piled up in a mountain shape. It is also possible to determine various work states, such as determination, and control the pump discharge amount according to the determined work state and the operation amount of the operation member.

(3) The characteristics of the pump required flow rate are not limited to the above-described embodiment.
(3-1) For example, the characteristics BR, BD, AR1 shown in FIG. 11 may be the same characteristics as the characteristics AR2, and only the characteristics AD during the lift-down operation may be different from the characteristics AR2.
(3-2) For example, the characteristics AD, BD, BR shown in FIG. 11 may be the same as the characteristics AR2, and only the characteristics AR1 during the lift-up operation during excavation work may be different from the characteristics AR2.
(3-3) For example, the characteristics AR1 and AD shown in FIG. 11 may be the same as the characteristics AR2, and only the characteristics BR and BD during the bucket operation may be different from the characteristics AR2.
(3-4) For example, the characteristic BR and the characteristic BD shown in FIG.

(4) Each characteristic of the pump required flow rate shown in FIG. 11 is not limited to the case of combining linear proportional characteristics with different slopes, and may be a quadratic proportional relation or stepwise stepwise. You may make it change to.

(5) The wheel loader 100 is not limited to the one using a series hybrid system in which the traveling motor 402 is driven by the electric power generated by the generator motor 401 driven by the engine 10 and the wheels 141 are driven by the traveling motor 402. For example, a parallel hybrid system in which the wheels 141 are driven by at least one of the engine 10 and the generator motor 401 driven by the engine 10 may be used.

(6) The present invention is not limited to the case of a hybrid work vehicle, and the present invention is applied to a work vehicle that transmits the rotational force of the engine 10 to the propeller shaft via a torque converter or transmission without providing a traveling motor. May be applied (see, for example, JP-A-2005-155494). In addition, the present invention may be applied to a work vehicle having a so-called HST travel drive circuit in which a variable displacement hydraulic pump and a variable displacement hydraulic motor are connected in a closed circuit by a pair of pipe lines (for example, JP, 6-8755, A).

(7) In the above-described embodiment, the example in which the engine 10 is employed as the prime mover for driving the main pump 11 and the pilot pump 12 has been described, but the present invention is not limited to this. An electric motor may be employed as a prime mover, and the main pump 11 and the pilot pump 12 may be driven by the electric motor.

(8) Although an example in which a capacitor is employed as the power storage element 404 has been described, the present invention is not limited to this. As the storage element, for example, a secondary battery such as a lead storage battery or a lithium ion battery may be adopted.

(9) In the above-described embodiment, the output management unit 240 determines that the steering cylinder 130, the arm cylinder 110, and the bucket cylinder 120 are operating based on the hydraulic pressure request output _{Pwr_pmp_req.} It is not limited. _Instead of the hydraulic pressure request output P _{wr_pmp_req} , the operation of the operation member may be detected to determine which of the steering cylinder 130, the arm cylinder 110, and the bucket cylinder 120 is operating. In addition, a sensor that detects the expansion / contraction speed of the steering cylinder 130, the arm cylinder 110, and the bucket cylinder 120 may be provided, and the output management unit 240 may determine using the detection speed detected by the sensor.

(10) In the above embodiment, the wheel loader has been described as an example. However, the present invention can also be applied to various work vehicles having an arm such as a hydraulic excavator and a work tool at the tip of the arm.
(11) In the above-described embodiment, the example in which the working tool is a bucket has been described, but the present invention is not limited to this.

(12) In the above-described embodiment, the arm operation detection means and the work implement operation detection means are configured by the pilot pressure sensors 201a, 201b, 202a, 202b, but the present invention is not limited to this. For example, an angle sensor that detects the rotation angle of the arm operation lever 301 or the bucket operation lever 302 may be used.

(13) In the embodiment described above, hydraulic pilot type control levers are employed for the arm operation lever 301 and the bucket operation lever 302, and hydraulic pilot type direction control valves are provided for the arm control valve 310 and the bucket control valve 320. Although adopted, the present invention is not limited to this. For example, an electromagnetic pilot is employed for the arm operation lever 301 and the bucket operation lever 302, and the spool is driven by an electric signal output from the main controller 200 to the arm control valve 310 and the bucket control valve 320. A directional control valve of the type may be employed.

(14) The hydraulic pressure request calculation unit 220 is not limited to the configuration in which the maximum value is selected by the maximum value selection unit 226 with reference to each characteristic of the pump required flow rate map as shown in FIG.

  As long as the characteristics of the present invention are not impaired, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. . The embodiments and modifications used for the description may be configured by appropriately combining them.

  9 natural mountain, 10 engine, 10c engine controller, 11 main pump, 11a swash plate, 12 pilot pump, 19 hydraulic oil tank, 100 wheel loader, 100D travel drive device, 100E travel electric device, 100H work hydraulic device, 101 arm, 102 Bucket, 109 Center pin, 110 Arm cylinder, 110a Bottom side oil chamber, 110b Rod side oil chamber, 120 Bucket cylinder, 120a Bottom side oil chamber, 120b Rod side oil chamber, 130 Steering cylinder, 140F Front car body, 140R Rear car body , 141 wheel, 141F front wheel, 141R rear wheel, 142F front wheel side axle, 142R rear wheel side axle, 143F differential device, 143R differential device, 145 propeller 146, 147 connecting portion, 151 cab, 152 engine compartment, 161 forward / reverse switching lever, 162 accelerator pedal, 163 brake pedal, 164 ignition switch, 200 main controller, 201a, 201b, 202a, 202b pilot pressure sensor, 203 Pump pressure sensor, 204 Arm angle sensor, 206 Forward / reverse selector switch, 207 Accelerator pedal sensor, 208 Traveling motor rotation speed sensor, 209 Brake pedal sensor, 210 Power storage management unit, 211 Pump regulator, 220 Hydraulic pressure calculation unit, 221 Working state Determination unit, 224 Flow rate calculation unit, 225 switching unit, 226 Maximum value selection unit, 227 Output calculation unit, 229 Arm height determination unit, 230 Travel request calculation unit, 240 Output management unit, 250 Target Rotational speed calculation unit, 260 generator motor control unit, 270 tilt angle control unit, 280 travel motor / brake control unit, 290 brake control unit, 301 arm operation lever, 301a, 301b pilot valve, 301d detent solenoid, 302 bucket operation lever , 302a, 302b Pilot valve, 303 Steering wheel, 310 Arm control valve, 320 Bucket control valve, 330 Main relief valve, 390 Center bypass line, 391 Parallel oil passage, 392, 393, 395 Check valve, 401 Generator motor , 402 traveling motor, 404 power storage element, 410 M / G inverter, 420 traveling inverter, 440 converter

Claims (7)

A work vehicle having an arm and a work tool that moves up and down by the rotation of the arm,
A hydraulic pump driven by a prime mover;
A first hydraulic cylinder for the arm driven by pressure oil discharged from the hydraulic pump;
A second hydraulic cylinder for the working tool driven by pressure oil discharged from the hydraulic pump;
A first directional control valve that controls the flow of pressure oil supplied from the hydraulic pump to the first hydraulic cylinder;
A second directional control valve for controlling the flow of pressure oil supplied from the hydraulic pump to the second hydraulic cylinder;
An arm operating member for operating the first directional control valve;
A work tool operating member for operating the second direction control valve;
First operation detecting means for detecting an operation of the arm operating member;
A discharge amount control means for controlling a discharge amount of the hydraulic pump according to an operation direction and an operation amount of the arm operation member detected by the first operation detection means ;
Second operation detecting means for detecting an operation of the work tool operating member,
Characteristics of the discharge amount of the hydraulic pump according to the operation direction and operation amount of the work tool operation member when the work tool operation member is operated alone, and the arm operation member when the arm operation member is operated alone It differs from the discharge amount characteristic of the hydraulic pump according to the operation direction and operation amount of the arm operation member,
The working tool is a bucket rotatably attached to the tip of the arm,
The second operation detection means includes a dump operation amount that is an operation amount in the dump side operation direction for causing the bucket to perform a dump operation, and a rollback that is an operation amount in the rollback side operation direction for causing the bucket to perform a roll back operation. Detect the operation amount,
When the predetermined operation amount is detected by the second operation detection unit, the discharge amount control unit detects a rollback operation amount equivalent to the predetermined operation amount by the second operation detection unit. Compared to the above , a work vehicle characterized in that the discharge amount of the hydraulic pump is increased . The work vehicle according to claim 1,
A work state detecting means for detecting a work state of the work vehicle;
The discharge amount control means changes the discharge amount of the hydraulic pump according to the operation amount in the predetermined operation direction of the arm operation member according to the work state detected by the work state detection means. vehicle. In the work vehicle according to claim 1 or 2 ,
Wherein the first operation detection means is the operation amount of the arm down side operation direction for lowering the lift-up manipulation amount you and the work tool is arms raised side operating direction of the control amount for increasing the working tool Detect liftdown operation amount ,
The discharge amount control means detects a lift-up operation amount equivalent to the predetermined lift-down operation amount by the first operation detection means when a predetermined lift-down operation amount is detected by the first operation detection means. A work vehicle characterized in that the discharge amount of the hydraulic pump is reduced as compared with the time when In the work vehicle according to claim 3 ,
The rate of increase in the discharge amount of the hydraulic pump according to the increase in the lift-up operation amount when the lift-up operation amount detected by the first operation detection means is greater than or equal to a predetermined value is the lift-up operation amount. A work vehicle characterized by being smaller than a rate of increase in the discharge amount of the hydraulic pump in accordance with an increase in the lift-up operation amount when the value is less than a value. In the work vehicle according to claim 3 or claim 4 ,
The first directional control valve has a power-down position in which the bottom oil chamber of the first hydraulic cylinder is used as a tank pressure and pressure oil is supplied to the rod oil chamber, and the bottom oil chamber and rod of the first hydraulic cylinder. Each has a float-down position with each side oil chamber as a tank pressure, and is configured to switch from the power-down position to the float-down position in accordance with an increase in the lift-down operation amount,
The discharge amount control means increases the discharge amount of the hydraulic pump according to an increase in the lift-down operation amount when the lift-down operation amount detected by the first operation detection means is less than a predetermined amount, A work vehicle characterized in that when the lift-down operation amount detected by the operation detection means is greater than or equal to the predetermined amount, the discharge amount of the hydraulic pump is decreased according to the increase in the lift-down operation amount. The work vehicle according to claim 2,
The work state detection means detects at least whether the work vehicle is in an excavation work state;
When the excavation work state is detected by the work state detection means, the discharge amount control means is configured to control the hydraulic pump according to the operation amount in the arm raising side operation direction of the arm operation member for raising the work tool. A work vehicle characterized in that a discharge amount is made smaller than when the excavation work state is not detected. In the work vehicle according to any one of claims 1 to 6 ,
When the arm operation member and the work tool operation member are operated simultaneously, the discharge amount control means is configured to discharge the hydraulic pump according to the operation amount of the arm operation member and operate the work tool operation member. A working vehicle that selects a larger one of the discharge amounts of the hydraulic pump according to the amount.

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