JP4725406B2 - Power source device for hybrid work machines - Google Patents

Description

  The present invention relates to a power source device for a hybrid work machine that uses both engine power and electric power of a power storage device.

  2. Description of the Related Art Hybrid work machines (for example, excavators) that take a so-called parallel drive form are known.

  In this parallel system, the hydraulic pump and the generator motor that performs the generator action and the motor action are driven by a common power source, and the hydraulic actuator is driven by the hydraulic pump. It is configured to charge the battery and to assist the engine by causing the generator motor to perform a motor action by the discharging force of the power storage device at an appropriate time.

  According to such a hybrid work machine, energy saving can be realized by reducing the load on the engine and operating the engine in a high efficiency range.

Further, in this hybrid work machine, as shown in Patent Documents 1 and 2, a pump required power that is a power required by the hydraulic pump is obtained according to the load of the hydraulic actuator, and according to the pump required power. A technique for increasing or decreasing the power of a generator motor for assisting the engine (controlling the power distribution between the engine and the generator motor) is known.
JP 2005-237178 A JP 2005-233164 A

  In this known technique, the pump required power, which is a premise for determining the power distribution between the engine and the generator motor, is calculated based on the detected value by detecting the discharge pressure, the discharge amount, and the like of the hydraulic pump with a sensor.

  Once the power distribution is determined, the generator motor power is fixed to the distribution value as long as the pump required power does not change.

  However, when there is a measurement error such as an offset in the sensor for detecting the pump required power, a deviation occurs between the calculated value and the actual value.

  Here, when the calculated value of the pump required power based on the detected value shifts to a smaller one than the actual pump required power, the power becomes insufficient, and the power of the generator motor to assist at this time is fixed as described above. The shortage will be borne by the engine. As a result, the engine is overloaded and may stall.

  As a measure for preventing engine stall, it is conceivable to perform so-called ESS control in which the engine speed is detected and the hydraulic pump is subjected to horsepower reduction control as the engine speed decreases. In this ESS control, the generator motor power is effectively used. This is not a good idea because the original meaning of the hybrid is lost.

  On the other hand, when the calculated value of the required pump power based on the detected value is shifted to a larger value than the actual value, the generator motor is in an over-assist state and the rotation speed of the generator motor is increased, and the engine connected thereto May over-rotate and the engine may be damaged.

  Also, when there is a difference in performance due to individual differences or aging of the engine or generator motor itself, a difference in required pump power occurs, causing the same problem as described above.

  Accordingly, the present invention provides a power source device for a hybrid work machine that can prevent engine overload and over-rotation due to a shift in power required for the pump, on the premise that the generator motor power is effectively used. .

According to the first aspect of the present invention, the hydraulic pump that drives the hydraulic actuator and the generator motor that performs the generator action and the motor action are driven by an engine as a common power source, and the power storage device is driven by the generator action of the generator motor. In the power source device of the work machine that is configured to perform the electric motor action that assists the engine by driving the generator motor by the electric power of the power storage device while being charged ,
(I) Obtain the maximum engine power corresponding to the target engine speed determined based on the accelerator signal,
(II) determine the pump required power is the power required for the above SL hydraulic pump,
(III) Find the excess and deficiency of the engine maximum power with respect to this pump demand power,
(IV) determining distribution of outgoing DENDEN motive power to the generator motor is put in order to eliminate the excess or shortage of the engine maximum power,
(V) obtaining a deviation between the target engine speed and the actual engine speed caused by the difference between the calculated value of the pump required power and the actual value ;
(VI) in the direction of the deviation of this is resolved that to correct the power distribution of the generator motor
It is one that is sea urchin configuration.

  The invention of claim 2 comprises the following means in the configuration of claim 1.

  (A) Engine maximum power setting means for setting the maximum engine power based on the target engine speed.

  (B) A generator motor maximum power setting means for setting the maximum power of the generator motor based on the rotation speed of the generator motor.

  (C) Pump maximum power setting means for setting pump maximum power from the set engine maximum power and generator motor maximum power.

  (D) Pump required power calculating means for obtaining pump required power that is power required by the hydraulic pump.

  (E) Power distribution means for determining distribution of the generator motor power that the generator motor should output for engine assist based on the pump required power and the set engine maximum power and generator motor maximum power.

  (F) Based on the deviation between the target engine speed and the actual engine speed, the correction power that is insufficient or excessive of the required pump power is obtained, and this correction power is allocated to the pump maximum power and the generator motor maximum power. As a power correction unit that distributes based on a predetermined distribution rate and outputs corrected power command values for the generator motor and the hydraulic pump based on the distribution result.

  According to a third aspect of the present invention, in the configuration of the second aspect, the distribution ratio in the power correction means is such that the ratio of the maximum pump power on the low speed side increases on the high speed side in accordance with the actual engine speed. The generator motor maximum power ratio is set to be large.

  According to a fourth aspect of the present invention, in the configuration of any one of the first to third aspects, the pump required power calculating means is configured to calculate the pump required power based on a discharge pressure, a discharge amount, and a rotation speed of the hydraulic pump. It is a thing.

  According to the present invention, attention is paid to the fact that the difference between the calculated value of the pump required power and the actual value appears as a deviation between the target engine speed and the actual engine speed, and based on this deviation (in the direction in which the deviation is eliminated). Since the generator motor power distribution is corrected, when the pump required power is shifted due to a sensor measurement error for obtaining the pump required power, the generator motor power is increased or decreased to control the engine load or engine speed. Can be kept appropriate. That is, engine stall due to engine overload and damage due to overspeed can be prevented, and a stable engine operating state can be ensured.

  According to the invention of claim 3, the distribution ratio of the correction power (the ratio of the distribution between the generator motor maximum power and the pump maximum power) is determined according to the actual engine speed of the pump maximum power on the low engine speed side. Since the ratio is set so that the ratio of the generator motor maximum power increases on the high speed side, for example, if the engine speed is low, the output of the generator motor is also low, so the distribution ratio of the generator motor maximum power is reduced. Instead, control is performed such that the pump horsepower reduction amount is increased, and in the opposite case, the generator motor maximum power (assist amount) is increased. As a result, a more stable engine operating state can be ensured.

  As shown in FIG. 1, a variable displacement hydraulic pump 3 and a generator motor 4 that performs a generator action and a motor action are connected in parallel to an engine 1 via a power divider 2, and these are driven by the engine 1. The

  The hydraulic pump 3 is provided with a hydraulic actuator (not shown) via a control valve (provided for each actuator, but shown here as an assembly of a plurality of control valves) (for example, each cylinder of the boom, arm, bucket, A traveling hydraulic motor) is connected, and these hydraulic actuators are driven by the pressure oil supplied from the hydraulic pump 3.

  On the other hand, a power storage device (for example, a lithium ion capacitor) 7 is connected to the generator motor 4 via an inverter 6.

  The inverter 6 switches between the generator operation and the motor operation of the generator motor 4, controls the generated power, the current or torque as the motor, and charges / charges the power storage device 7 according to whether the generator output of the generator motor 4 is excessive or insufficient. Control the discharge.

  The tilt of the hydraulic pump 3 and the torque of the generator motor 4 are controlled by the controller 8.

  The controller 8 detects values detected by the detection means, that is, a target rotational speed of the engine 1 (the rotational speed at the time of engine maximum power output obtained based on the accelerator signal) ωegref, the actual rotational speed ωeg, the hydraulic pump 3 Each information of the discharge pressure (pump pressure) p and the discharge amount q is input, and based on these information, a torque command for the generator motor 4 and a tilt command for the hydraulic pump 3 are output from the controller 8.

  The configuration and operation of the controller 8 will be described with reference to the block diagram of FIG. 2 and the flowcharts of FIGS.

  The controller 8 includes, as basic means, a pump required power calculating means 9 for calculating a pump required power that is a power required by the hydraulic pump 3, an engine maximum power setting means 10 for setting the maximum power of the engine 1, and a generator motor. Generator maximum power setting means 11 for setting the maximum power of 4, pump maximum power setting means 12 for setting the maximum power of the hydraulic pump 3, power distribution means 13 for determining the power distribution of the generator motor 4 with respect to the pump required power, It has.

  The power correction means includes a correction power calculation means 14, a correction power distribution ratio calculation means 15, a generator motor power command correction means 16, and a pump maximum power command correction means 17.

  Further, a generator motor torque command means 18 and a pump tilt control (PQ control) means 19 are provided as a control system.

  At the time of control, first, the detection of the target engine speed ωegref and the actual rotation speed ωeg (step S1 in FIG. 3), the detection of the pump pressure p and the pump discharge amount q (step S2 in the same) are performed, and then the required pump power is calculated. In the means 9, the pump required power PWp is calculated by substituting the input pump pressure p, pump discharge amount q, and actual engine speed ωeg into the following equation (step S3).

Required pump power PWp = pump pressure p × pump discharge q × engine actual speed ωeg
When a plurality of hydraulic pumps 3 are provided, the required pump power PWp is calculated by multiplying the total value of p × q of each pump by the actual engine speed ωeg.

  Next, in the engine maximum power setting means 10, a value corresponding to the detected engine target speed ωegref is set as the engine maximum power PWegmax from the engine maximum power map created in advance using the engine target speed ωegref as a parameter. (Step S4).

  Further, the generator motor maximum power setting means 11 considers the actual engine speed ωeg as the generator motor speed, and corresponds to the detected actual engine speed ωeg from the map of the generator motor maximum power created in advance using this as a parameter. The value to be set is set as the generator motor maximum power PWmgmax (step S5).

  Then, the pump maximum power setting means 12 calculates and sets the pump maximum power PWpmax by the following equation as the sum of the engine maximum power PWegmax and the generator motor maximum power PWmgmax set (step S6).

Pump maximum power PWpmax = Engine maximum power PWegmax + Generator motor maximum power PWmgmax
Further, in the power distribution means 13, based on the engine maximum power PWegmax, the generator motor maximum power PWmgmax, and the pump request power PWp, the generator motor power command value PWmgref to be shared by the generator motor 4 of the pump request power PWp is determined. Calculate (step S7).

  This power distribution will be explained in detail. When the pump required power PWp exceeds the engine maximum power PWegmax, it is necessary to compensate for the excess (engine power shortage). Output as command value PWmgref. That is, the power assist operation by the generator motor 4 is performed.

  However, as described above, the pump required power PWp may deviate from the actual value due to a sensor measurement error or the like. Therefore, it is necessary to correct the power distribution command value based on the required pump power value including such a deviation.

  Further, the pump maximum power value PWpmax set based on the target engine speed ωegref needs to be corrected according to the actual engine speed ωeg.

  This correction is performed in steps S8 to S11 in FIG. 4 by power correction means (correction power calculation means 14, correction power distribution ratio calculation means 15, generator motor power command correction means 16, pump maximum power command correction means 17). .

  That is, the correction power calculation means 14 pays attention to the fact that if there is a deviation in the pump required power PWp, it appears as a difference between the engine target speed ωegref and the actual engine speed ωeg, and the engine target speed ωegref and the actual engine speed ωeg Based on the deviation, the correction power PWrvse is calculated by the following equation (step S8).

Correction power PWrvse = correction gain Krvse × (engine target speed ωegref−engine actual speed ωeg)
Here, when the correction power PWrvse> 0, it indicates that the pump required power is detected as being smaller than the actual value (pump absorption power) (the engine load is large), and there is a possibility of engine stall. On the other hand, when the correction power PWrvse <0, it indicates that the requested pump power is detected as being larger than the actual value (the engine load is small), and there is a possibility of engine overspeed.

  The corrected power distribution rate calculating means 15 calculates the corrected power distribution rate α from the map of FIG. 5 created in advance using the actual engine speed ωeg as a parameter (step S9).

  The corrected power distribution ratio α is a ratio of dividing the corrected power PWrvse into the amount to be added to the generator motor maximum power PWmgmax (increase the assist force) and the amount to be reduced from the pump maximum power PWpmax (to reduce horsepower). As shown in FIG. 5, the actual engine speed ωeg is used as a parameter and is determined in the range of 0 ≦ corrected power distribution ratio α ≦ 1.

  Here, the actual engine speed ωeg is used as a parameter for determining the correction power distribution ratio α. From the viewpoint of securing a stable engine operation state, the engine stall speed is high if the engine actual speed ωeg is low, and Since the output of the generator motor 4 is also low, it is desirable to reduce the distribution rate α of the generator motor maximum power PWmgmax and to increase the pump horsepower reduction instead. In the opposite case, the generator motor maximum power (assist amount) PWmgmax This is because it is desirable to increase the value.

  The generator motor power command correction means 16 calculates a generator motor power command correction value PW′mgref by the following equation (step S10).

Generator motor power command correction value PW′mgref = Generator motor power command value PWmgref
+ Correction power distribution ratio α × correction power PWrvse
Further, the pump maximum power command correction means 17 calculates a pump maximum power command correction value PW′pmax by the following equation (step S11).

Pump maximum power command correction value PW'pmax = Pump maximum power PWpmax +
(Correction power distribution ratio α-1) × Correction power PWrvse
Based on the two command correction values PW′mgref and PW′pmax obtained in this way, the generator motor torque command means 18 divides the generator motor power command correction value PW′mgref by the generator motor speed ωmg. To calculate the generator motor torque command and output it to the inverter 6 (step S12).

  Note that the generator motor torque command means 18 uses a value obtained by converting the actual engine speed ωeg by the gear ratio converter 20 as the generator motor speed ωmg.

  The pump tilt control means 19 calculates the maximum pump tilt from the pump maximum power command correction value PW′pmax, the pump pressure p, and the actual engine speed ωeg, and tilts the hydraulic pump 3 so as not to exceed this. Take control.

  As described above, based on the deviation between the target engine speed ωegref of the engine 1 and the actual engine speed ωeg, the distribution of the generator motor power is corrected in a direction in which the deviation is eliminated, thereby causing an engine stall or overload caused by an overload of the engine 1. Damage due to rotation can be prevented.

  In the above embodiment, as shown in FIG. 5, the correction power distribution rate α is linearly changed with a certain degree according to the actual engine speed ωeg. It is also possible to adopt a configuration in which it is different between the number range and the high speed range, or is changed in a curvilinear or broken line shape according to the actual engine speed ωeg.

1 is an overall configuration diagram of a power source device according to an embodiment of the present invention. It is a block diagram which shows the structure of the controller of the apparatus. It is a flowchart for demonstrating the effect | action of a controller. FIG. 4 is a continuation flowchart of FIG. 3. It is a characteristic figure of the correction power distribution rate in a controller.

DESCRIPTION OF SYMBOLS 1 Engine 2 Power divider 3 Hydraulic pump 4 Generator motor 5 Control valve 6 Inverter which controls a generator motor 7 Power storage device 8 Controller 9 Controller pump demand power calculation means 10 Engine maximum power setting means 11 Generator motor maximum power setting means 12 Pump maximum Power setting means 13 Power distribution means 14 Correction power calculation means 15 Correction power distribution rate calculation means 16 Generator motor power command correction means 17 Pump maximum power command correction means 18 Generator motor torque command means 19 Pump tilt control means

Claims (4)

The hydraulic pump that drives the hydraulic actuator and the generator motor that performs the generator action and the motor action are driven by an engine as a common power source, and the power storage device is charged by the generator action of the generator motor. In the power source device of the work machine configured to perform a motor action that assists the engine by driving the generator motor by the power of the device ,
(I) Obtain the maximum engine power corresponding to the target engine speed determined based on the accelerator signal,
(II) determine the pump required power is the power required for the above SL hydraulic pump,
(III) Find the excess and deficiency of the engine maximum power with respect to this pump demand power,
(IV) determining the distribution of outgoing DENDEN motive power to the generator motor is put in order to eliminate the excess or shortage of the engine maximum power,
(V) obtaining a deviation between the target engine speed and the actual engine speed caused by the difference between the calculated value of the pump required power and the actual value ;
(VI) in the direction of the deviation of this is resolved that to correct the power distribution of the generator motor
Hybrid working machine of the power source device, characterized in that I is urchin configuration. The power source apparatus for a hybrid work machine according to claim 1, further comprising the following means.
(A) Engine maximum power setting means for setting the maximum engine power based on the target engine speed.
(B) A generator motor maximum power setting means for setting the maximum power of the generator motor based on the rotation speed of the generator motor.
(C) Pump maximum power setting means for setting pump maximum power from the set engine maximum power and generator motor maximum power.
(D) Pump required power calculating means for obtaining pump required power that is power required by the hydraulic pump.
(E) Power distribution means for determining distribution of the generator motor power that the generator motor should output for engine assist based on the pump required power and the set engine maximum power and generator motor maximum power.
(F) Based on the deviation between the target engine speed and the actual engine speed, the correction power that is insufficient or excessive of the required pump power is obtained, and this correction power is allocated to the pump maximum power and the generator motor maximum power. As a power correction unit that distributes based on a predetermined distribution rate and outputs corrected power command values for the generator motor and the hydraulic pump based on the distribution result.   The distribution rate in the power correction means is set so that the ratio of the maximum pump power on the low speed side increases and the ratio of the generator motor maximum power increases on the high speed side according to the actual engine speed. The power source apparatus for a hybrid work machine according to claim 2, wherein   4. The pump required power calculating means is configured to calculate pump required power based on a discharge pressure, a discharge amount, and a rotation speed of a hydraulic pump, according to any one of claims 1 to 3. Power source device for hybrid work machines.

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