JP2002359935A - Charging/discharging control device for power storing part of hybrid work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge/discharge control device for the power storing part of a hybrid work machine which enables use of a small-sized battery and prolongs its life time. SOLUTION: This charging/discharging control device for the power storing part of a hybrid work machine is provided with a generator driven by a motive power source, a motor for driving the working machine, and a power storing part which is connected to the generator and the motor electrically, stores power outputted by the generator and the motor respectively, and outputs power for dividing the motor. The control device is provided with an energy detection means for detecting the kinetic energy and the potential energy of the work machine, a stored power detecting means for detecting the quantity of stored power in the power storing part, a controller which has an energy computing part for computing the kinetic energy and the potential energy of the work machine, and a motive power source control unit for controlling the motive power source, on the basis of the computed energies.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power storage unit charge / discharge control device for a hybrid working machine.

[0002]

2. Description of the Related Art A working machine such as a hydraulic excavator is configured to drive an actuator by an engine. However, since the work is often performed with a constant engine output even under a light load, the fuel efficiency of the engine is poor. There's a problem. There are also environmental problems such as noise and exhaust gas. Therefore, the engine, the generator driven by the engine, the motor driving the load, and the battery are combined, and the battery is charged with the power generated by the generator at a light load or the regenerative power returned from the motor driven by the load at the time of braking. There has been proposed a hybrid working machine that extracts power from a battery under heavy load. As a result, the load on the engine is leveled, thereby solving problems such as fuel consumption, noise, and exhaust gas.

[0003]

The prior art described above has the following problems. In a hybrid work machine, the number of parts of a generator, an electric motor, and ancillary equipment for controlling them is increased, and since the battery is large, a large space for storing these ancillary equipment and a battery is required. There is a problem of weight. In addition, the upper and lower limits of the charged amount of the battery are set in advance, and when the charged amount of the battery becomes smaller than the lower limit, the engine is started to start charging, and when the charged amount becomes larger than the upper limit, the engine is started. Is stopped and charging is completed. For this reason, the power storage amount may exceed the upper and lower limit values and overshoot, so that the power remaining width, which is the range between the minimum value and the maximum value of the power storage amount, becomes large, and a large-capacity battery must be mounted. In addition, there is a problem that the life of the battery is short. In addition, the smaller the value of the charged amount is near the predetermined optimum value of the remaining amount, the smaller the battery size and the longer the life.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a power storage unit charge / discharge control device for a hybrid work machine that requires only a small battery and extends the life of the battery.

[0005]

Means for Solving the Problems, Functions and Effects In order to achieve the above object, a first invention is directed to a generator driven by a power source, a motor driving a work machine, and an electric power generator and a motor. A power storage unit charge / discharge control device for a hybrid work machine, comprising: a power storage unit configured to connect and store power output by each of the generator and the motor and output power for driving the motor. Detecting means for detecting the amount of power stored in the power storage unit, an energy calculating unit for calculating kinetic energy and potential energy of the work machine, and a power source for controlling a power source based on the calculated energy And a controller having a control unit.

According to the first aspect, when the position of the working machine is high, the potential energy is large, and in the braking process in which the potential energy in the next step becomes small, a large regenerative electric power returns from the motor driving the working machine. In addition, when the turning speed of the working machine is high, the kinetic energy is large, and a large regenerative power returns in the braking process in which the kinetic energy in the next step becomes small. Since the power source is controlled by predicting the regenerative electric power of the next step based on the energy of the work machine calculated in this way, the power storage amount does not exceed the upper and lower limit values and does not overshoot, and the remaining power range is reduced. Further, since the kinetic energy and the potential energy of the working machine are effectively used as regenerative electric power, an efficient working machine can be obtained.

According to a second aspect based on the first aspect, the controller sets the charge / discharge threshold of the power storage unit to be small when the calculated kinetic energy and potential energy of the work machine are large, and increases the charge / discharge threshold when the energy is small. It is configured to be set.

According to the second aspect of the invention, when the calculated value of the energy is large, a large regenerative power returns. Therefore, the charge / discharge threshold value is set to a small value, so that the power source is stopped earlier and the power source is delayed. When the calculated value of the energy is small, only a small amount of regenerative power returns. Therefore, the charge / discharge threshold is set to a large value to speed up the start of the power source and delay the stop. This allows
The power storage unit does not overcharge or overdischarge, and the fluctuation range of the power storage amount can be suppressed to a small value.Therefore, a power storage unit charge / discharge control device of a hybrid work construction machine that requires only a small power storage unit and extends the life of the power storage unit is required. can get.

According to a third aspect based on the first or second aspect, the power source is an engine having a fixed output, and the controller controls charging and discharging of the power storage unit by starting and stopping the engine.

According to the third aspect, the engine can always be used at an optimum output point with good fuel efficiency and little exhaust gas. In addition, since charging and discharging are performed only by starting and stopping the engine, charging and discharging can be reliably controlled.

According to a fourth aspect based on the first or second aspect, the power source is an engine, and the controller controls charging and discharging of the power storage unit by making the output of the engine variable.

According to the fourth aspect, when the charged amount is smaller than the predetermined value, the output of the power source is set to be large according to the difference (for example, in proportion to the difference), and the charged power is quickly stored. Further, when the charged amount is larger than the predetermined value, the output of the power source is set to be small and the power is gradually stored, and when the charged amount becomes larger than the predetermined threshold value, the output of the power source is set to zero. Thus, the output of the power source is finely controlled, so that the fluctuation range of the charged amount is further reduced, and a more compact and longer-life power storage unit can be provided.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of a charge / discharge control device 10 of the present embodiment. In the present embodiment, the excavator 11 will be described as an example of a working machine. Traveling device 12
A boom 14 is attached to an upper swing body 13 that swings on the boom by a boom cylinder 15 so as to be able to move up and down. The arm 16 is rotatably attached to the tip of the boom 14 and the bucket 17 is rotatably attached to the tip of the arm 16. The arm 16 is attached to the boom 14 by an arm cylinder 18, and the bucket 17 is attached to the arm 16. , Respectively, by the bucket cylinder 19. Each cylinder 15, 18, 19 has a boom motor 20, an arm motor 21, a boom pump 23, an arm pump 24, and a bucket pump 2 driven by a bucket motor 22.
5 is supplied. Each of the boom pump 23, the arm pump 24, and the bucket pump 25 is a tandem pump having two pumps. Oil from the pump. At this time, one pump supplies the oil sucked from the accumulator 99 and the other pump supplies the oil discharged from the head side of the cylinder to the bottom side. To reduce the cylinder, a part of the oil discharged from the bottom side is supplied to the head side by the other pump, and the rest is sent to the accumulator 99. Upper revolving superstructure 13 and traveling device 1
2 is directly driven by a revolving body electric motor 26 and a pair of left and right traveling device electric motors 27 without interposing hydraulic pressure. Boom cylinder 1 as energy detector as detector
5 and a rotational speed detector 29 of the upper revolving unit 13 are attached respectively.
From 29, the stroke St and the turning speed Re are output.

The charge / discharge control device 10 has an engine 30, a generator 31, a controller 32, a battery 33, and a power converter 34. A generator 31 is connected to an output shaft of the engine 30 as a power source, and power generated by the generator 31 is input to a battery 33 via a normal charging circuit 35 of a power converter 34. The power conversion unit 34 includes a normal charging circuit 35, a motor operation circuit 36, a regenerative charging circuit 37
have. The electric power discharged from the battery 33 as a power storage unit is supplied to each motor 20,
21, 22, 26 and 27. The electric power regenerated by the boom motor 20 and the revolving-body electric motor 26 is input to the battery 33 via the regenerative charging circuit 37. In FIG. 1 and the subsequent figures, the flow of the regenerative electric power is indicated by a dotted line.

The controller 32 includes an energy calculating unit 4
1, a threshold calculator 42, an engine output calculator 43, and an engine controller 44. The energy calculator 41 includes:
The revolving speed Re and the stroke St are input, and the kinetic energy E of the upper revolving unit 13 is calculated by the equations (1) and (2).
k and the position energy Ep of the boom 14 are calculated, and the calculated energies Ek and Ep are output to the threshold value calculation unit 42. Ek = Cr × ABS (Re) (1) Ep = Cs × St (2) where Cr and Cs are preset. The constant value ABS (Re): represents the absolute value of Re. The threshold value calculating unit 42 calculates the variable large threshold value Bd as the charge / discharge threshold value according to the equations (3) and (4) based on the input energies Ek and Ep. The variable small threshold value Bs is calculated, and the calculated threshold values Bd and Bs are output to the engine control unit 44. Bd = Bdc-Ek-Ep (3) Bs = Bsc-Ek-Ep (4) where Bdc is a predetermined upper limit. Value Bsc: Preset fixed lower limit value The upper limit value Bdc and the lower limit value Bsc are values for setting the range of the appropriate charge amount of the battery 33, for example, 60
% And 40%, respectively.

The engine output calculator 43 includes a battery 33
Remaining amount detector 4 as a charged amount detecting means mounted on the battery
The engine output Pe is calculated by the equation (5) based on the stored amount Br of the battery 33 detected in step 5, and the calculated engine output Pe is output to the engine control unit 44. Pe = Pem + Kp × (Bm−Br) (5) where, Pem: optimal value of engine output in consideration of fuel consumption, noise, exhaust gas, etc. Kp: constant value preset Bm: battery Optimum value of remaining power in consideration of service life Optimum remaining power value Bm is 60% of upper and lower limit values Bdc and Bsc.
If each is set to 40%, it is set to 50%.

The engine controller 44 includes a variable large threshold Bd and a variable small threshold Bs input from the threshold calculator 42, an engine output Pe input from the engine output calculator 43,
A command value Gs to be output to the governor device 46 for controlling the rotation speed of the engine 30 is set as shown in FIG. 2 based on the charged amount Br input from the remaining amount detector 45. That is, as shown in FIG. 2A, the switching signal Cs changes from on to off when the charged amount Br increases from a value smaller than the variable small threshold Bs and exceeds the variable large threshold Bd. The switching signal Cs changes from off to on when the storage amount Br decreases from a value greater than the variable large threshold Bd and falls below the variable small threshold Bs. Switching signal C
s is input to the relay contact 47 as shown in FIG. 2B, and is closed when turned on and opened when turned off. When the switching signal Cs is on, the command value Gs has a value corresponding to the engine output Pe input from the engine output calculation unit 43. When the switching signal Cs is off, the command value Gs has a zero value and the engine 30 is stopped.

Here, referring to FIG. 3, the stroke St, the potential energy Ep, the boom regenerative power Wp, the turning speed Re, the kinetic energy Ek, the slewing body are taken as an example of the excavating and loading work which is a typical work of the hydraulic shovel 11. A description will be given of a temporal change of the regenerative power Wk. During the time t1 to t2, the upper revolving unit 13 is turned toward the dump truck while raising the bucket 17 full of soil, and during the time t2 to t3, the soil is loaded on the dump truck and the bucket 17 is emptied. After time t3, the bucket 17 is turned toward the excavation position while lowering the bucket 17. As shown in FIG. 3A, the arm 16 and the bucket 17 move to a higher position as the stroke St becomes longer from time t1.
As shown in (b), the potential energy Ep of the boom 14 increases. At time t2, since the bucket 17 becomes empty, the potential energy Ep sharply decreases as shown in FIG. 3B, and after time t3, the bucket 17 is lowered, so that the stroke St is shortened. When the stroke St is shortened, the boom motor 20 is driven via the boom pump 23, and the boom regenerative power Wp returns to the regenerative charging circuit 37 as shown in FIG. On the other hand, FIG.
Since the turning starts at times t1 and t3 as shown in FIG. 3D, the kinetic energy Ek of the upper turning body 13 has a value corresponding to the turning speed Re as shown in FIG. When approaching the dump truck and the excavation position, the revolving-body electric motor 26 is driven by the braking force of the revolving motion, and the revolving-body regenerative power Wk returns to the regenerative charging circuit 37 as shown in FIG.

As described above, in the operation of the hydraulic excavator 11, if the stroke St becomes longer, the stroke St always becomes shorter next. When the stroke St is shortened, the boom regenerative power W corresponding to the position energy Ep of the arm 16 and the bucket 17 when the stroke St is long
p returns to the regenerative charging circuit 37. Also, the turning speed R
Next, when e increases, the turning speed Re always decreases. When the slewing speed Re decreases, the slewing body regenerative power Wk corresponding to the kinetic energy Ek of the upper slewing body 13
Returns to the regenerative charging circuit 37. The present invention calculates the magnitude of the regenerative power that returns based on the state of each working machine of the hydraulic shovel 11, and when the regenerative power is large, delays the timing at which the engine 30 starts charging the battery 33,
This is an invention of a control device that advances the charging start timing when the value is small, and always keeps the charge amount of the battery at an appropriate value. In addition,
Upper revolving superstructure 13, boom 14, arm 1 involved in work
6. All of the buckets 17 are called work machines.

The operation of the present embodiment having the above configuration will be described. This embodiment is an embodiment in which the variable large threshold value Bd and the variable small threshold value Bs are calculated by equations (3) and (4), and the engine output Pe is calculated and set by equation (5) (case C below). is there. However, for ease of comparison, cases A and B described below are also described here. Case A: a conventional technique, in which the variable magnitude thresholds Bd and Bs are fixed to the upper and lower limit values Bdc and Bsc, and the engine output Pe is fixed to the engine output optimum value Pem. 3), (4)
When the engine output Pe is fixed to the engine output optimum value Pem, the case C: the variable magnitude thresholds Bd and Bs are calculated by the equations (3) and (4).
And the engine output Pe is calculated by equation (5).

Case A: When the variable magnitude thresholds Bd and Bs are fixed to the upper and lower limits Bdc and Bsc, and the engine output Pe is fixed to the optimum engine output Pem. FIG. 4 shows the state of charge Br, the engine output Pe and the load Lp. FIG. At time t11, the storage amount Br is smaller than the lower limit value Bsc, so that the switching signal Cs described with reference to FIG. 2A is turned on, and the relay contact 47 described with reference to FIG. The engine output Pe output from 43, that is, the optimum engine output value Pem is output to the governor 46 as a command value Gs. And
The engine 30 outputs the engine output optimum value Pem. At this time, since the engine output optimum value Pem is larger than the load Lp, the battery 33 is charged and the charged amount B
r is increasing. The storage amount Br increases and the upper limit value Bdc
At time t12 when the switching signal Cs becomes larger than the switching signal Cs from ON to OFF as shown in FIG. 2A and the relay contact 47 is opened, the command value Gs becomes zero and the engine 30
Stops. After time t12, the charged amount Br is consumed for the load Lp, so the charged amount Br decreases and becomes smaller than the lower limit value Bsc. At time t13, the engine output optimum value Pem again becomes the command value Gs. The engine 30 outputs the engine output optimum value Pem.

As described above, the charged amount Br changes based on the engine output Pe and the load Lp, but the capacity of the battery 33 to be mounted is generally the minimum value Brs of the charged amount Br.
Is determined in accordance with the remaining power width Brr of the difference between the maximum remaining power Brd and the maximum value Brd, and the life of the battery 33 is shorter as the remaining power width Brr is larger. In addition, when the remaining power width Brr is small and the charged amount Br is always near the optimum remaining value Bm, only a small battery is required and the life of the battery 33 is long.

Case B: When the variable magnitude thresholds Bd and Bs are calculated according to the equations (3) and (4) and the engine output Pe is fixed at the engine output optimum value Pem. 5 shows a temporal change of the load Lp. The load Lp from the time t20 to the time t21 is a change when the upper revolving unit 13 of the hydraulic excavator 11 is turning and the stroke St of the boom cylinder 15 is lengthened to raise the boom 14, so that the kinetic energy Ek is changed. And the potential energy Ep is large. Thereby, the variable large threshold value Bd calculated by the equations (3) and (4)
And the variable small threshold value Bs becomes smaller as shown in FIG. That is, when the kinetic energy Ek and the potential energy Ep are large, the regenerative power returning to the battery 33 is large, and the amount of charge by the engine 30 can be small. Therefore, the variable magnitude thresholds Bd and Bs are set small and the amount of stored electricity Br is small. By the way, the engine 30 is started or stopped. As described above, since the start / stop of the engine 30 is controlled by estimating the regenerative power, the power to be charged exceeds the charging capability of the battery, or the power to be charged becomes too low to fall below the discharging capability of the battery. Never do.

At time t21, the storage amount Br is smaller than the variable small threshold value Bs, so that the switching signal Cs is ON, the relay contact 47 is closed, and the engine output Pe output from the engine output calculation unit 43, that is, the engine engine output is output. The optimum value Pem is output to the governor 46 as a command value Gs. Then, the engine 30 outputs the optimum engine output value Pem. Further, at this time, since the engine output Pe is larger than the load Lp, the battery 33 is charged and the charged amount Br is increasing. At time t22 when the amount of stored electricity Br increases and becomes larger than the variable large threshold value Bd, the switching signal Cs changes from on to off and the relay contact 47 opens, so that the command value Gs becomes zero and the engine 30 stops. After time t22, the charged amount Br is consumed for the load Lp, so that the charged amount Br decreases and the variable small threshold value Bs decreases.
At time t23 when the engine output optimal value Pem becomes smaller than the command value Gs, the engine output optimal value Pem is output to the governor 46 again.
Output m.

Case C: Variable thresholds Bd and Bs are calculated by equations (3) and (4) and engine output Pe is calculated by equation (5). FIG. 6 shows the state of charge Br, engine output Pe and load. The time change of Lp is shown. The change from time t30 to t31 is the same as in case B. That is, since the load Lp is a change when the upper revolving structure 13 of the hydraulic excavator 11 is turning and the stroke St of the boom cylinder 15 is lengthened and the boom 14 is raised, the kinetic energy Ek and the potential energy Ep are large. . This gives equation (3),
The variable large threshold value Bd and the variable small threshold value Bs calculated by (4) become small as shown in FIG. That is, when the kinetic energy Ek and the potential energy Ep are large, the regenerative power is large, and the amount of charge by the engine 30 can be small. Has been stopped.

On the other hand, the engine output Pe is calculated by the equation (5), and as shown between the time t30 and the time t31, the storage amount Br
Is smaller than the remaining amount optimum value Bm, the engine output Pe is set to be larger than the engine output optimum value Pem in accordance with (for example, in proportion to) the difference to increase the amount of charge by the engine 30. As a result, the manner in which the amount of stored electricity Br decreases is more gradual than the manner in which the amount of stored electricity Br decreases between times t20 and t21 shown in FIG.

At time t31, the storage amount Br is smaller than the variable small threshold value Bs, so that the switching signal Cs is on, the relay contact 47 is closed, and the engine output Pe output from the engine output calculation unit 43 is equal to the command value Gs. Is output to the governor device 46. The engine 30 outputs the engine output Pe. Further, at this time, since the engine output Pe is larger than the load Lp, the battery 33 is charged and the charged amount Br is increasing. At time t32 when the amount of stored electricity Br increases and becomes larger than the variable large threshold value Bd, the switching signal Cs changes from on to off and the relay contact 47
Is opened, the command value Gs becomes zero, and the engine 30 stops. Since the charged amount Br is consumed for the load Lp, the charged amount Br decreases and becomes smaller than the variable small threshold value Bs. At the time t33, the engine output Pe again becomes the command value Gs and is transmitted to the governor device 46 again. Since the output is performed, the engine 30 outputs the engine output Pe.

The effect of this embodiment will be described. As shown in FIGS. 4, 5, and 6, the remaining power width Brr is the case A, B, C
The case B and the case C are 86% and 59% of the case A, respectively. As described above, according to the case C of the present embodiment, the remaining power width Brr can be suppressed small, so that the capacity, that is, the size of the battery 33 can be reduced to approximately 60% of the conventional battery 33, and The storage amount Br fluctuates near the optimum remaining amount Bm, so that the life of the battery 33 can be extended.

Although the present invention has been described using the engine 30 as a power source, other power sources such as a fuel cell may be used without being limited to this. Further, in the present invention, the battery 33 is described as the power storage unit, but a power storage unit such as a capacitor or a power storage unit having both a battery and a capacitor may be used. Further, in the present invention, the example in which the energies of the upper swing body 13 and the boom 14 are calculated has been described. However, the same effect can be obtained by adding the energies of the arm 16 and the bucket 17 to this. Expressions (1) and (2) can be generally expressed as Expressions (6) and (7). Ek = f (Re) (6) Ep = f (St) (7) For example, in the present invention, the kinetic energy Ek is calculated by the equation (1).
Is calculated by the product of Cr and ABS (Re).
And the square of Re.

In the present invention, the excavator 1
1 has been described as an example, but the present invention is also applicable to a dump truck 90, a rough terrain crane 70, and a wheel loader 50 shown in FIGS.

FIG. 7 shows a configuration diagram in which the present invention is applied to a dump truck 90. The charge / discharge control device 10 including the engine 30, the generator 31, the controller 32, the battery 33, and the power converter 34 has the same configuration as that described with reference to FIG. The power discharged from the battery 33 is supplied to the power conversion unit 34.
Front and rear wheel motors 91 and 92 and dump cylinder 9
3 is input to a dump motor 95 that drives a dump pump 94 that feeds oil to the pump 3. The dump pump 94 is a tandem pump, like the cylinder pumps 23, 24, and 25 described in FIG. In addition, each motor 91, 9
The electric power regenerated by the power generators 2 and 95 is input to the battery 33 via the electric power converter 34. The controller 32 receives the stroke Std of the dump cylinder 93, the vessel load Wd, and the vehicle speed Vd.

In the dump truck 90, the work of loading the soil into the vessel 96 at the loading location, traveling along a predetermined traveling route to the dumping location, and raising the vessel 96 by the dump cylinder 93 to discharge the soil. Many. Since the traveling route is substantially constant, it is easy to predict the discharge power or the regenerative power during uphill or downhill. Then, when the stroke Std of the dump cylinder 93 is long, it is easily predicted that the regenerative power will return due to the lowering of the vessel 96 in the next step. Therefore, the same effect as the effect when applied to the excavator 11 can be exerted by predicting the discharge / regeneration power during running and the regenerative power during operation of the dump cylinder 93.

FIG. 8 shows a configuration diagram in which the present invention is applied to a rough terrain crane 70. Engine 30, generator 3
1, controller 32, battery 33, power conversion unit 34
Is the same as the configuration described with reference to FIG. The electric power discharged from the battery 33 is passed through a power converter 34, and the boom-lift cylinder motor 71, the boom telescopic cylinder motor 72, the winch motor 73, the upper swing body motor 74, the axle motor 75, and the auxiliary motor 8
2 has been entered. Further, each of the electric motors 71, 72, 7
The power regenerated by 3, 74, 75, 82 is input to the battery 33 via the power converter 34. A boom hoist cylinder electric motor 71 is provided with a boom hoist pump 78 that feeds oil to a boom hoist cylinder 77 that raises and lowers a boom 76.
Drive. The boom telescopic cylinder motor 72 drives a boom telescopic pump 80 that feeds oil to a boom telescopic cylinder 79 that expands and contracts the boom 76. Boom hoisting pump 78
The boom expansion / contraction pump 80 is a tandem pump, similarly to the cylinder pumps 23, 24, and 25 described with reference to FIG. The winch motor 73 drives a winch (not shown) that lifts a load. The upper revolving superstructure motor 74 drives the upper revolving superstructure 81. Axle motor 7
5 drives a transmission mechanism (not shown) that mechanically connects the front and rear wheels 84 and 85. The accessory motor 82 drives an accessory pump 83 that feeds oil to an accessory (not shown) such as an outrigger. The turning speed Rer of the upper turning body 81, the strokes Str1 and Str2 of the boom up / down cylinder 77 and the boom telescopic cylinder 79, the winch hoisting speed Sr, the hoisting load Wr, and the vehicle speed Vr are input to the controller 32.

In the rough terrain crane 70, when lifting the load, the boom raising / lowering cylinder 77 and the boom telescopic cylinder 79 are extended. Each cylinder 7
When the strokes Str1 and Str2 of 7, 79 are lengthened, each stroke Str1 and S
Since tr2 is shortened, the potential energy of the boom that is increasing becomes smaller. When the potential energy is reduced, regenerative power is returned from the boom hoist cylinder motor 71 and the boom telescopic cylinder motor 72. Also, when the winch hoisting speed Sr and hoisting load Wr are large, the regenerative power always returns in the next step. Also,
When the swing speed of the upper swing body is high, the regenerative electric power at the time of braking always returns. As described above, the prediction of the regenerative power is easy, and the discharge at the time of traveling, the prediction of the regenerative power, and the like can be performed based on the detected vehicle speed Vr. Therefore, the same effect as the effect when applied to the hydraulic excavator 11 can be exhibited by predicting the discharge / regeneration power at the time of lifting and running.

FIG. 9 shows a configuration diagram in which the present invention is applied to a wheel loader 50. The charge / discharge control device 10 including the engine 30, the generator 31, the controller 32, the battery 33, and the power converter 34 has the same configuration as that described with reference to FIG. The power discharged from the battery 33 is supplied to the power conversion unit 34.
Are input to the boom cylinder electric motor 51, the bucket cylinder electric motor 52, and the auxiliary electric motor 53. Also,
The electric power regenerated by the electric motors 51, 52, 53 is input to the battery 33 via the electric power converter 34.
The boom cylinder motor 51 drives a boom cylinder pump 54 that feeds oil to a boom cylinder 55 that moves the bucket 59 up and down. The bucket cylinder motor 52 drives a bucket cylinder pump 56 that feeds oil to a bucket cylinder 57 that tilts the bucket 59. The boom cylinder pump 54 and the bucket cylinder pump 56 are tandem pumps, similarly to the cylinder pumps 23, 24, and 25 described in FIG. Auxiliary motor 53
Is an auxiliary equipment pump 58 for feeding oil to auxiliary equipment necessary for steering and the like.
Drive. The output shaft of the generator 31 is input to the torque converter 62 and drives the front and rear wheels 60 and 61 via the transmission 63. The configuration shown in FIG.
As the driving force of the wheel loader 50, the electric power output from the battery 33 and the mechanical output from the output shaft of the generator 31 are used in parallel, which is a so-called parallel hybrid type configuration. Each stroke St of the boom cylinder 55 and the bucket cylinder 57 is provided to the controller 32.
h1, Sth2, and the vehicle speed Vh are input.

In the wheel loader 50, the load 6
4, the bucket 59 is inserted into the bucket 4, and the bucket 59 is excavated by the boom cylinder 55 and the bucket cylinder 57, so that the bucket 59 is fully loaded. After braking, there are many V-shape operations in which the vehicle advances toward a transport vehicle such as a dump truck, dumps the bucket 59, and loads a load on the transport vehicle. Since the V-shape work is patterned, when moving from reverse to forward, the generator 3
It is easy to predict the regenerative electric power generated at the time of braking and the regenerative electric power returned in the next step when the boom cylinder 55 and the bucket cylinder 57 are long. Therefore, the prediction of the discharge and regenerative electric power during traveling and the respective cylinders 55, 57
The same effect as the effect when applied to the excavator 11 can be exhibited by predicting the regenerative electric power at the time of operation.

As described above, according to the present invention, a generator driven by a power source, a motor for driving a working machine, and a power generator which is electrically connected to the generator and the motor to store power output from the generator and the motor, respectively. In a power storage unit charge / discharge control device for a hybrid work machine including a power storage unit that outputs electric power for driving an electric motor, an energy detection unit that detects kinetic energy and potential energy of the work machine, and detects an amount of power stored in the power storage unit. The power storage device includes a power storage amount detecting unit, an energy calculating unit that calculates kinetic energy and potential energy of the work machine, and a controller having a power source control unit that controls a power source based on the calculated energy. As a result, when the position of the working machine is high, the potential energy is large, and a large regenerative electric power is returned from the electric motor driving the working machine in a braking process in which the potential energy in the next step becomes small. In addition, when the turning speed of the working machine is high, the kinetic energy is large, and a large regenerative power returns in the braking process in which the kinetic energy in the next step becomes small. Since the power source is controlled by predicting the regenerative electric power in the next step based on the energy of the work machine calculated in this way, the power storage unit does not overcharge or overdischarge, and the fluctuation width of the power storage amount can be suppressed small. Thus, a power storage unit charge / discharge control device for a hybrid work machine that requires only a small power storage unit and extends the life of the power storage unit is obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment according to the present invention.

FIG. 2 is an explanatory diagram of an engine control unit.

FIG. 3 is an explanatory diagram of potential energy and kinetic energy.

FIG. 4 is an explanatory diagram of temporal changes in the remaining power, the engine output, and the load when the variable magnitude threshold is fixed to the upper and lower limits and the engine output is fixed to the optimum engine output.

FIG. 5 is an explanatory diagram of a temporal change of the remaining power, the engine output, and the load when the variable magnitude threshold is calculated by the equations (3) and (4) and the engine output Pe is fixed at the optimum engine output value. .

FIG. 6 is an explanatory diagram of temporal changes in the remaining power, engine output, and load when a variable magnitude threshold is calculated by equations (3) and (4) and an engine output is calculated by equation (5).

FIG. 7 is an explanatory diagram when the present invention is applied to a dump truck.

FIG. 8 is an explanatory view when the present invention is applied to a rough terrain crane.

FIG. 9 is an explanatory diagram when the present invention is applied to a wheel loader.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Charge / discharge control apparatus, 11 ... Hydraulic excavator, 12 ... Traveling apparatus, 13 ... Upper revolving body, 14 ... Boom, 15 ... Boom cylinder, 16 ... Arm, 17 ... Bucket, 18 ... Arm cylinder, 19 ... Bucket cylinder, 20: boom motor, 21: arm motor, 22: bucket motor,
23 ... boom pump, 24 ... arm pump, 25 ... bucket pump, 26 ... revolving unit electric motor, 27 ... traveling device electric motor, 28 ... stroke detector, 29 ... rotation speed detector,
30 ... engine, 31 ... generator, 32 ... controller,
33 ... battery, 34 ... power conversion unit, 35 ... normal charging circuit, 36 ... motor operating circuit, 37 ... regenerative charging circuit, 41
... Energy calculation unit, 42 threshold value calculation unit, 43 ... Engine output calculation unit, 44 ... Engine control unit, 45 ... Remaining amount detector,
46: governor device, 47: relay contact, 99: accumulator, St: stroke, Re: turning speed, Gs:
Command value, Ep: potential energy, Ek: kinetic energy, B
d: variable large threshold, Bs: variable small threshold, Bdc: upper limit,
Bsc: lower limit value, Pe: engine output, Pem: engine output optimum value, Bm: remaining amount optimum value, Br: power storage amount, Cs
... Switching signal, Wp ... Boom regenerative power, Wk ... Slewing body regenerative power, Lp ... Load.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 10/48 H02J 7/00 P H02J 7/00 7/34 A 7/34 B60K 9/00 ZHVC F-term (Reference) 2D003 AA01 AB06 AC09 BA05 BB01 CA10 DA04 DB03 DB05 DC01 5G003 AA07 BA01 DA15 FA06 5G060 AA04 AA05 CA21 DB07 5H030 AS08 BB10 DD20 FF41 5H115 PA15 PG09 PI16 PO02 PO17 PU01 PU19 PU21 PV01 QA07 SE03 SE05 SE05 SE05

Claims (4)

[Claims] A generator (31) driven by a power source (30), a motor driving a work machine, and a generator (31) and an electric motor connected to the motor to output each of the generator (31) and the motor A power storage unit for a hybrid work machine, comprising: a power storage unit (33) that stores power to be driven and outputs power for driving an electric motor; and an energy detection unit that detects kinetic energy and potential energy of the work machine. A power storage amount detecting means for detecting the amount of power stored in the power storage unit; an energy calculation unit (41) for calculating kinetic energy and potential energy of the work machine; and a power source control for controlling a power source (30) based on the calculated energy. A charge / discharge control device for a power storage unit of a hybrid working machine, comprising: a controller (32) having a unit (44). 2. The charge / discharge control device for a power storage unit of a hybrid work machine according to claim 1, wherein the charge / discharge thresholds (Bd, Bs) of the power storage unit (33) are set when the calculated kinetic energy and potential energy of the work machine are large. Set small and charge / discharge threshold (Bd, Bs) when energy is small
The charging / discharging control device for a power storage unit of a hybrid working machine, characterized in that: 3. The power storage unit charge / discharge control device according to claim 1, wherein the power source (30) is an engine having a fixed output, and the controller (32) stores power by starting and stopping the engine. Department
(33) A charge / discharge control device for a power storage unit of a hybrid working machine, wherein the charge / discharge control is performed. 4. The power storage unit charge / discharge control device for a hybrid working machine according to claim 1, wherein the power source (30) is an engine, and the controller (32) makes the output of the engine variable so that the power storage unit operates. (33) A charge / discharge control device for a power storage unit of a hybrid working machine, wherein the charge / discharge control is performed.