JP2007262978A - Output control device for hybrid working machine and output control method for hybrid working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit fluctuation of engine output against fluctuation of work load by a simple structure and stabilize an operation condition of an engine in relation to an output control device for a hybrid working machine and an output control method for the hybrid working machine. <P>SOLUTION: The output control device 10 for the parallel type hybrid working machine provided with a hydraulic pump 1, the engine 2 connected to the hydraulic pump 1 in such a manner that the same can transmit power to the hydraulic pump 1, an electric motor 3 connected to the hydraulic pump 1 in such a manner that the same can drive the hydraulic pump 1 independently from the engine 2, a battery 5, is provided with an output variable detection means 6 detecting a variable corresponding to an output condition of the hybrid working machine, an average value calculation means 7a calculating an average value of the variable detected by the output variable detection means 6 during a predetermined period of time, and an output establishing means 7b establishing magnitude of output of the engine 2 according to the average value calculated by the average value calculation means 7a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an output control device for a hybrid work machine equipped with an engine and a motor generator, and an output control method for the hybrid work machine.

  In recent years, hybrid work machines in which both an engine and a motor (electric motor) are mounted as drive sources of the work machine have been developed. In this type of hybrid work machine, the motor combines the function of rotating the hydraulic pump and engine using the electric power of the battery and the function of a generator (generator) that charges the battery with the electric energy generated by the rotating motion. ing. Using this, the engine power is assisted by the motor power when the work load is large and the output required for the hydraulic pump is high, and when the work load is small, the surplus engine power is converted into electric power. As shown in FIG. As described above, the driving force of the engine and the motor can be combined according to the working state so that the work can be carried out efficiently.

  On the other hand, there are various types of work performed using a hydraulic excavator, and fluctuations in the work load state also occur in a hybrid work machine equipped with a motor. In other words, even if the engine output is assisted by the motor output, the power stored in the battery decreases if the work load is always greater than the engine output. As a result, if sufficient motor output cannot be obtained, the work load cannot be output. If the engine output is large relative to the work load, the surplus energy will be charged, but if it becomes overcharged, the energy will be wasted and the fuel consumption of the engine will be reduced. End up.

In response to such a problem, Patent Document 1 discloses a configuration in which the motor output added to the engine output is controlled to increase or decrease according to the work content. For example, if it is recognized that a relatively high-load work mode (working state) such as excavation or traveling is detected based on the determination based on the lever operation amount, the motor output is set to a large value. When it is recognized that this is a low-load work mode, the motor output is set to be small. As a result, workability can be improved by assisting the output of the work machine with a motor in a high load state, while energy saving can be enhanced by suppressing excessive assist in a low load state. It has become.
JP 2001-3397 A

  However, in the output control as described above, since the motor output fluctuates when the work mode changes, the magnitude of the engine output fluctuates transiently when the fluctuation amount of the motor output is large. May show unstable behavior. For example, in the technique described in Patent Document 1, when excavation work and horizontal smoothing work are alternately performed and the load level of the work greatly fluctuates, the engine output fluctuates as the motor output fluctuates. There is a problem that it tends to be steep and energy loss is likely to occur.

For example, in the technique disclosed in Patent Document 1, the work mode is recognized based on the lever operation amount. However, the lever operation method has a large individual difference for each operator, and the work mode is recognized accurately. There is also a practical problem that is difficult.
The present invention has been made in view of such a problem, and with a simple configuration, it is possible to suppress engine output fluctuations with respect to work load fluctuations, and to stabilize the engine operating state. An object of the present invention is to provide a hybrid work machine output control device and a hybrid work machine output control method.

  In order to achieve the above object, an output control device for a hybrid work machine according to a first aspect of the present invention includes a hydraulic pump, an engine connected to the hydraulic pump so that power can be transmitted, and the engine independently of the engine. A parallel-type hybrid work machine comprising a motor that can drive a hydraulic pump and that can generate power using the power of the engine, and a battery that is connected to transfer power to and from the motor An output variable detecting means for detecting a variable corresponding to the output state of the hybrid work machine, and an average of the variables detected by the output variable detecting means during a preset predetermined time An average value calculating means for calculating a value as a state average value, and an output setting means for setting the magnitude of the output of the engine according to the state average value calculated by the average value calculating means; It is characterized by comprising.

The average value here means a statistical index obtained by leveling the dispersion of the variables detected by the output variable detecting means. For example, arithmetic mean (arithmetic) It is one of the averages calculated using various methods such as average), geometric average, and harmonic average.
Further, in the output control device for a hybrid work machine according to the second aspect of the present invention, the output variable detecting means detects the amount of charge of the battery as the variable, and the average value calculating means is used for the predetermined time. An average value of the charge amount is calculated, and the output setting means increases the output of the engine when the average value of the charge amount is larger than a predetermined value set in advance. When the average value is smaller than a predetermined value set in advance, the output of the engine is reduced.

  Further, in the output control device for a hybrid work machine according to claim 3 of the present invention, the output variable detection means detects the magnitude of the pump output of the hydraulic pump as the variable, and the average value calculation means An average value of the pump output for a predetermined time is calculated, and the output setting means sets the average value of the pump output as the magnitude of the output of the engine.

  According to a fourth aspect of the present invention, there is provided an output control device for a hybrid work machine according to the present invention, wherein the output variable detection means detects the discharge pressure of hydraulic oil discharged from the hydraulic pump, and the hybrid work Lever operation amount detection means for detecting the operation amount of the operation lever of the machine, based on the discharge pressure detected by the discharge pressure detection means and the operation amount detected by the lever operation amount detection means The pump output of the hydraulic pump is calculated.

  Further, in the output control device for a hybrid work machine according to claim 5 of the present invention, the output variable detecting means detects the discharge pressure of the hydraulic oil discharged from the hydraulic pump, and the hydraulic pump Swash plate angle detecting means for detecting the swash plate angle of the swash plate angle based on the discharge pressure detected by the discharge pressure detection means and the swash plate angle detected by the swash plate angle detection means It is characterized in that the magnitude of the pump output of the hydraulic pump is calculated.

The output control device for a hybrid work machine according to claim 6 of the present invention further includes pump output detection means for detecting an output of the hydraulic pump as a work load of the hybrid work machine, and the output setting means includes the output setting means, The output of the engine is subtracted from the output of the hydraulic pump detected by the pump output detection means, and the output of the motor is set.
The output control device for a hybrid work machine according to claim 7 of the present invention further comprises a rotation speed detection means for detecting the rotation speed of the motor, and the output setting means determines the magnitude of the output of the motor. The target torque of the motor is set by dividing by the rotation number detected by the rotation number detection means.

  According to an eighth aspect of the present invention, there is provided an output control device for a hybrid work machine according to the present invention, wherein a rotational speed detecting means for detecting the rotational speed of the motor and a correspondence relationship between the rotational speed of the engine and the output of the engine are stored. Storage means, wherein the output setting means calculates the target rotational speed of the engine calculated based on the state average value calculated by the average value calculation means and the correspondence stored in the storage means. , And is set as a target rotational speed of the motor.

  According to a ninth aspect of the present invention, there is provided an output control method for a hybrid work machine according to the present invention, wherein the hydraulic pump, an engine connected to the hydraulic pump so that power can be transmitted, and the hydraulic pump can be driven independently of the engine. And a parallel hybrid work machine output control method comprising a motor connected to be able to generate electric power using the power of the engine, and a battery connected to transfer power to and from the motor. An output variable detection step for detecting a variable corresponding to the output state of the hybrid work machine; an average value calculation step for calculating an average value of the variable during a predetermined time set in advance as a state average value; And an output setting step for setting the output level of the engine in accordance with the average state value.

  In the output control method for a hybrid work machine according to claim 10 of the present invention, in the output variable detection step, the charge amount of the battery is detected as the variable, and in the average value calculation step, the output at the predetermined time is detected. An average value of the charge amount is calculated, and in the output setting step, when the average value of the charge amount is larger than a predetermined value set in advance, the output of the engine is increased, and the charge amount When the average value is smaller than a predetermined value set in advance, the output of the engine is reduced.

  In the output control method for a hybrid work machine according to an eleventh aspect of the present invention, in the output variable detecting step, the magnitude of the pump output of the hydraulic pump is detected, and in the average value calculating step, the output at the predetermined time is detected. An average value of the pump output is calculated, and in the output setting step, the average value of the pump output is set as a magnitude of the output of the engine.

  According to the output control device for a hybrid work machine and the output control method for a hybrid work machine according to the present invention (claims 1 and 9), the work load of the hybrid work machine is controlled by controlling the output of the engine according to the state average value. The fluctuation of the engine output with respect to the fluctuation of can be suppressed. That is, since the engine output is controlled based on a parameter obtained by averaging the output state of the hybrid work machine, the engine output can be gradually changed, and the engine operating state can be stabilized.

  In addition, according to the output control device for a hybrid work machine and the output control method for a hybrid work machine according to the present invention (claims 2 and 10), the engine output level is set in accordance with the amount of charge of the battery. Abrupt fluctuations in output can be suppressed, and at the same time, the charge amount of the battery can be controlled in the vicinity of a predetermined value set in advance. That is, both the engine output and the charge amount of the battery can be stabilized. Further, the amount of charge of the battery is easy to detect, and can be realized with a simple configuration without cost.

  In addition, according to the output control device for a hybrid work machine and the output control method for a hybrid work machine according to the present invention (claims 3 and 11), since the magnitude of the engine output is set in accordance with the pump output, the engine is accurately set. The output can be kept constant. Moreover, since the magnitude | size of a pump output can be correctly calculated, for example from the discharge pressure and discharge flow rate of a hydraulic pump, it can grasp | ascertain easily.

Moreover, according to the output control apparatus (Claim 4) of the hybrid work machine of this invention, the magnitude | size of a pump output can be grasped | ascertained easily. In addition, since the magnitude of the pump output is calculated using the lever operation amount, for example, in a working machine having an electric operation lever in which it is relatively easy to grasp the lever operation amount, an accurate pump Output calculation is possible.
Moreover, according to the output control apparatus (Claim 5) of the hybrid work machine of this invention, the magnitude | size of a pump output can be grasped | ascertained easily. For example, in a work machine provided with a mechanical operation lever, it is possible to accurately calculate the pump output.

Further, according to the output control device for a hybrid work machine of the present invention (Claim 6), the output of the engine is subtracted from the output of the hydraulic pump to set the output of the motor. By doing so, it becomes possible to control the engine output at the same time. That is, the engine output can be freely controlled by controlling the motor output.
Further, according to the output control device for a hybrid work machine of the present invention (Claim 7), accurate output control can be performed by calculating the target torque of the motor.

  According to the output control device for a hybrid work machine of the present invention (Claim 8), the motor output can be easily controlled by calculating the target rotational speed of the engine connected coaxially with the motor. . For example, the applicability to conventional control for controlling the target engine speed is high.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 4 are diagrams for explaining an output control device of a hybrid work machine according to an embodiment of the present invention. FIG. 1 is a schematic configuration diagram showing an overall configuration of the output control device, and FIG. FIG. 3 is a graph showing a correspondence relationship between the difference V _d between the target charge amount (target SOC) of the battery and the actual charge amount (actual SOC) and the correction amount a of the engine target output W _t in this output control device. FIG. 4 is a perspective view of a hydraulic excavator to which the present output control device is applied.

[Constitution]
〔overall structure〕
The output control device 10 is applied to a hybrid hydraulic excavator 20 shown in FIG. The hydraulic excavator 20 includes a lower traveling body 21 equipped with a crawler type traveling device, and an upper revolving body 22 that is rotatably mounted on the lower traveling body 21. A working device 23 such as a boom or an arm is provided on the front side of the upper swing body 22, and an engine room 24 is disposed on the rear side.

Inside the engine room 24, an engine 2 and a motor / generator 3, which are driving sources of the hydraulic excavator 20, and the hydraulic pump 1 are disposed. The hydraulic pump 1 is a supply source of hydraulic oil to a hydraulic circuit that drives the working device 9 of the hydraulic excavator, the crawler device of the lower traveling body 21, and the like.
The engine 2 is one of the drive sources of a hydraulic excavator 20 configured as a general internal combustion engine, and is connected to the hydraulic pump 1 so that power can be transmitted. On the other hand, the motor / generator 3 is a second drive source independent of the engine 2, and is connected to the hydraulic pump 1 so as to be able to transmit power as in the engine 2.

  The motor / generator 3 has a function as a motor (electric motor) and a function as a generator (generator). For example, when functioning as a generator, power is generated by rotating using torque input from the engine 2 and the battery 5 is charged. Further, when functioning as a motor, the motor 5 rotates using the power of the battery 5 via the inverter 4, and the driving force of the motor is added to the driving force of the engine 2 and output to the hydraulic pump 1 side. . Alternatively, when the engine 2 is stopped, the engine 2 can be started using the driving force of the motor / generator 3.

The inverter 4 is a power conversion device for converting a direct current into an alternating current. The direct current from the battery 5 is converted into an alternating current having an arbitrary frequency by the inverter 4 and supplied to the motor / generator 3. As a result, the motor / generator 3 rotates at a rotation speed corresponding to the given frequency.
As shown in FIG. 1, the upstream and downstream drive force transmission shafts of the motor / generator 3 are connected to the drive shaft of the engine 2 and the drive shaft of the hydraulic pump 1 directly or via a gear in the motor / generator 3. Are connected coaxially and rotate together. Hereinafter, the motor / generator 3 is simply referred to as the motor 3.

  The hydraulic excavator 20 includes a parallel hybrid work machine in which the engine 2, the motor 3 and the hydraulic pump 1 are connected in series, or a series / parallel hybrid work machine in which a part of the actuator is motorized. Thus, according to the working state of the hydraulic excavator 20, the work can be performed by combining the driving forces of the engine 2 and the motor 3.

FIG. 1 shows an electric operation lever (lever operation) for setting the operation amount of the control valve 8 and the actuator 9 and the actuator 9 interposed on the hydraulic circuit to which the hydraulic oil is supplied by the hydraulic pump 1. An amount detection means) 11, a hydraulic pressure gauge (discharge pressure detection means) 12, and a motor rotation speed sensor 13 are shown.
The actuator 9 is representatively shown as one of hydraulic actuators such as a hydraulic cylinder for extending and retracting the work device 23 and a hydraulic motor for rotating the traveling device 21. The operation lever 11 is representatively shown as one of operation levers for setting the operation amount of these hydraulic cylinders and hydraulic motors.

On the other hand, the control valve 8 is a control valve that is controlled to open and close in accordance with the operation amount L of the operation lever 11 by the operator. The hydraulic oil discharged from the hydraulic pump 1 is supplied to the actuator 9 with the flow rate and flow direction controlled by the control valve 8.
The oil pressure gauge 12 is a sensor that detects the discharge pressure P of hydraulic fluid discharged from the hydraulic pump 1. The motor rotation speed sensor 13 is a sensor that detects the rotation speed N of the motor 3.

This output control device 10 is applied to the hydraulic excavator 20 as described above. As shown in FIG. 1, the output control apparatus 10 includes a battery voltmeter (output variable detection means) 6 and a controller 7.
The battery voltmeter 6 is a sensor that detects a charge amount (actual SOC) V of the battery 6 as a variable corresponding to the output state of the excavator 10. The charge amount V of the battery 6 detected here is input to the controller 7. The lever operation amount L, the hydraulic oil discharge pressure P from the hydraulic pump 1 and the rotational speed N of the motor 3 are also input to the controller 7 in the same manner.

  The controller 7 is an electronic control device for controlling the motor 3 in accordance with the output state of the hydraulic excavator 20. The controller 7 stores a functional unit for processing signals input from the sensors, a functional unit for controlling the frequency of the alternating current converted by the inverter 4, a control program, a control map, and the like. Functional units (storage devices such as ROM and RAM), a functional unit (central processing unit such as CPU) for performing arithmetic processing, a time counter, and the like.

[Internal configuration of controller 7]
The internal configuration of the controller 7 will be described in detail. As shown in FIG. 1, the controller 7 includes an average value calculation unit (average value calculation unit) 7a and a motor output setting unit (output setting unit) 7b.
Average value calculating section 7a is for calculating a preset average value of the charging amount V input from the battery voltmeter 6 for a predetermined time period (state mean) V _a. Here, for example, the average value V _a of the charge amount V input for 30 seconds to 1 minute is calculated. For example, during the charging amount V inputted from the battery voltmeter 6 for a predetermined time, measured as often as desired, and calculates the arithmetic mean of the data measured as an average value V _a. The average value V _a calculated here is input to the motor output setting unit 7b.

The motor output setting unit 7b determines the output level of the engine 2 (engine target output W _t ) and the output level of the motor 3 (motor target output) according to the average value V _a calculated by the average value calculation unit 7a. W _m ) is set. Specifically, a difference V _d between a predetermined charge amount V _t set in advance and the average value V _a is calculated, and the following three types of control are performed according to the sign of the difference V _d , and engine target and calculates the target drive torque T _m of a motor 3 while changing the output W _t.

In the present embodiment, the output of the hydraulic pump 1, i.e., so that the work load of the working machine 20 is a control to match the total output of the engine target output W _t and the target motor output W _m is carried out ing. Engine target output W _t is the initial value is set in advance, while the target motor output W _m of which are calculated in each case in accordance with the output state of the working machine 20. The predetermined charge amount V _t is stored in the motor output setting unit 7b.

(1) When V _d > 0 In this case, the motor output setting unit 7b increases the engine target output W _t by a predetermined amount “a” to increase the magnitude of power output from the engine 2. To implement. That is, in this case, since the average value V _a of the charge amount V is smaller than the predetermined charge amount V _t , the output of the motor 3 is set by setting the ratio of the output that the engine 2 should bear to the work load slightly larger. Therefore, the further decrease in the charge amount V is suppressed.

The motor output setting section 7b is a target motor output W _m, calculated from the output of the hydraulic pump 1 at the time (i.e., the work load) W _p as the result of the subtraction of the target engine output W _t. The output W _p of the hydraulic pump 1 is calculated as the product of the discharge pressure P of the hydraulic oil discharged from the hydraulic pump 1 and the discharge flow rate Q of the hydraulic oil calculated based on the lever operation amount L. It has become.

(2) If in this case a V _d = 0, the motor output setting unit 7b performs a control that does not change the target engine output W _t. That is, in this case, since the average value V _a of the charge amount V is equal to the predetermined charge amount V _t , the conventional control is performed without correcting the target output of the engine 2.

(3) In the case of V _d <0 In this case, the motor output setting unit 7b controls the engine target output _Wt to decrease by a predetermined amount a set in advance to reduce the magnitude of power output from the engine 2. To implement. That is, in this case, since the average value V _a of the charge amount V is larger than the predetermined charge amount V _t , the output of the motor 3 can be set by setting the ratio of the output that the engine 2 should bear to the work load slightly smaller. This increases the ratio of the amount of charge, and further increases in the charge amount V are suppressed.

As in the case of V _d > 0, the motor output setting unit 7b subtracts the engine target output W _t from the output (ie, work load) W _p of the hydraulic pump 1 at that time for the motor target output W _m . Calculate as a thing.
Incidentally, when illustrating the correspondence relationship between the correction amount a difference V _d and the target engine output W _t in the case of the above (1) to (3), as shown in FIG.

[flowchart]
The present output control apparatus is configured as described above, and performs control according to the flowchart shown in FIG. This flowchart is repeatedly executed in the controller 7.
First, in step A10, information related to control is input to the controller 7. The information input here includes the charge amount V of the battery 5 detected by the battery voltmeter 6, the lever operation amount L of the operation lever 11, the hydraulic oil discharge pressure P detected by the hydraulic meter 12, and the motor rotation speed sensor. The rotational speed N of the motor 3 detected at 13. Further, in the following step A20, predetermined charge amount V _t is read in the motor output setting unit 7b.

Subsequently in step A30, the average calculation unit 7a, the average value V _a during a predetermined time amount of charge V input in step A10 is calculated. The average value V _a calculated here is input to the motor output setting section 7b, the process proceeds to step A40.
In step A40, the motor output setting section 7b, according to Equation 1 below, the difference V _d of predetermined charge amount V _t to the average value V _a calculated in step A30 is calculated.

V _d = V _t −V _a (Equation 1)
In the following step A50 and step A60, the sign of the difference V _d calculated in step A40 is determined. First, in step A50, the difference V _d is determined whether is positive. If V _d > 0, the process proceeds to step A70. On the other hand, when V _d ≦ 0, the routine proceeds to step A60, where it is determined whether or not the difference V _d is negative. If V _d <0, the process proceeds to step A80. Further, when neither of the conditions in Step A50 and Step A60 is met, V _d = 0, and the process proceeds to Step A90.

In step A70, the value obtained by adding the target engine output W _t and a predetermined amount a to the engine target output W _t is assigned, the process proceeds to Step A100. That is, in this case, control for increasing the magnitude of the output of the engine 2 is performed.
On the other hand, in step A80, the value of (the predetermined amount a sum of negative values) the predetermined amount a subtraction from the engine target output W _t to the engine target output W _t is assigned, the process proceeds to Step A100. That is, in this case, control for reducing the magnitude of the output of the engine 2 is performed. Further, the process proceeds to step A100 in step A90, without the size of the target engine output W _t is changed.

In step A100, the discharge flow rate Q of the hydraulic oil discharged from the hydraulic pump 1 is calculated based on the lever operation amount L input in step A10. Further, in step A110, the hydraulic pump 1 input in step A10 is calculated. Based on the discharge pressure P and the discharge flow rate Q calculated in step A100, the pump output _Wp is calculated according to the following equation 2.
W _p = Q × P (Formula 2)
In step A 120, front on the basis of the target engine output W _t that is set by the pump is calculated output W _p and step A70~ step A90 in step, the target motor output W _m is calculated according to Equation 3 below.

W _m = W _p −W _t (Formula 3)
In step A130, the motor target torque T _m from the target motor output W _m calculated by the input motor rotation speed N and the previous steps in step A10 is calculated, In step A140, the target motor torque in the motor 3 The inverter 4 is controlled so that _Tm occurs.

[Action / Effect]
With the configuration as described above, the output control device has the following operations and effects.
First, as shown in the control contents of step A50~ step A90, since the target engine output W _t is the output control target of the engine 2 is adapted to be set based on the charging amount V of the battery 5, the working Even if the load changes, the output of the engine 2 does not fluctuate rapidly. In other words, upon setting the target engine output W _t, the average value V _a of the charging amount V of the battery 5 at a given time is adapted to be referenced, according to the value which the engine output is smoothed out fluctuations in the charge amount V Will change. Therefore, the engine output can be controlled smoothly.

Further, in the control of the engine output, for example, as described in Patent Document 1, it is not necessary to determine the work mode based on the lever operation amount. In the present output control device, it is only necessary to have a means for detecting the charge amount V of the battery 5, the control configuration is simple, and it can be easily realized without cost.
Further, as shown in the control contents of step A70, the average value V _a of the charging amount V is lower than the predetermined charge amount V _t is controlled to increase the magnitude of the output of the engine 2 is made. That is, since the control of relatively reducing the output level of the motor 3 is performed, further reduction in the charge amount V can be suppressed.

On the other hand, as shown in the control contents of step A80, the average value V _a of the charging amount V is higher than the predetermined charge amount V _t is controlled to reduce the magnitude of the output of the engine 2 is made. That is, since control for relatively increasing the magnitude of the output of the motor 3 is performed, an excessive increase in the charge amount V can be suppressed.

Further, as shown in the control content of step A120, the motor target output W _m is set as a difference between the pump output W _p and the engine target output W _t , so that the output of the hydraulic pump 1 is the same as the output of the engine 2. This corresponds to the sum of the outputs of the motor 3. Therefore, the output of the engine 2 and the motor 3 with respect to the work load of the excavator 10 can be ensured, and the engine output can be accurately kept constant. Further, the magnitude of the pump output can be accurately calculated from the discharge pressure P and the discharge flow rate Q of the hydraulic pump 1, and is easy to grasp.
In this output control device, the discharge flow rate Q is calculated based on the lever operation amount L, and the magnitude of the pump output can be easily grasped.

[Modification]
Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the charge amount V of the battery 5 is detected as a variable corresponding to the output state of the hydraulic excavator 20, but instead of this, the pump output W _p of the hydraulic pump 1 (that is, work) It is also conceivable to adopt a configuration for detecting (load). That is, those in accordance with the variation of the average value of the pump output W _p in a given preset time, set the target engine output W _t.

In this case, the device configuration is substantially the same as that obtained by removing the battery voltmeter 6 from the above-described embodiment, but the average value calculation unit 7a in the controller 7 detects the magnitude of the pump output of the hydraulic pump 1. Will function as follows. The means for detecting the magnitude of the pump output is arbitrary. For example, the hydraulic oil discharge flow rate Q calculated from the lever operation amount L of the operation lever 11 and the discharge pressure P detected from the hydraulic gauge 12 are multiplied. things may be used as the pump output W _p. Alternatively, a swash plate angle sensor (swash plate angle detecting means) for detecting the swash plate angle (tilt angle) of the hydraulic pump 1 is prepared, and based on the swash plate angle and the discharge pressure P detected from the hydraulic pressure gauge 12. Thus, the pump output W _p may be calculated.

Further, the control content in the controller 7 is slightly different, and hereinafter, the control content of the present modification will be described with reference to FIG. Corresponding components will be described using the same reference numerals.
First, in step B10, information related to control is input to the controller 7. The information input here is the lever operation amount L of the operation lever 11, the hydraulic oil discharge pressure P detected by the hydraulic pressure gauge 12, and the rotational speed N of the motor 3 detected by the motor rotational speed sensor 13. In the subsequent step B20, the discharge flow rate Q of the hydraulic oil discharged from the hydraulic pump 1 is calculated based on the lever operation amount L input in step B10.

In the subsequent step B30, the pump output W _p is calculated based on the discharge pressure P of the hydraulic pump 1 input in step B10 and the discharge flow rate Q calculated in step B20, and the process proceeds to step B40.
In step B40, the average value calculation unit 7a calculates the average value W _{a of} the pump output W _p calculated in step B30 during a predetermined time. The average value W _a calculated here is input to the motor output setting unit 7b, and the process proceeds to Step B50.

In step B50, the motor output setting unit 7b calculates the motor target output W _m according to the following equation 4 based on the pump output W _p calculated in step B30 and the average value W _a calculated in the previous step. .
W _m = W _p −W _a (Expression 4)
In step B60, the motor target torque T _m from the target motor output W _m calculated by the input motor rotation speed N and the previous step is calculated in step B10, the following step B70, the motor target torque in the motor 3 The inverter 4 is controlled so that _Tm occurs.

With this control, in this modification, the engine target output W _t that is the output control target of the engine 2 is set based on the average value W _a of the pump output W _p , so that the work load Even if this changes, the output of the engine 2 does not fluctuate abruptly. In other words, even if work has changed suddenly, the value of the engine target output W _t will vary depending on the value smoothing the variation. Therefore, similarly to the control of the above-described embodiment, the engine output can be changed smoothly, and the operating state of the engine 2 can be stabilized.

  Further, for example, as described in Patent Document 1, it is not necessary to determine the work mode based on the lever operation amount, and further, refer to the charge amount V of the battery 5 as in the control of the above-described embodiment. There is no need to do. That is, the operating state of the engine 2 can be stabilized with a simpler configuration.

[Others]
In the above-described embodiment, the difference V _d between the charge amount V of the battery 5 and the target charge amount V _t and the correction amount a of the engine target output W _t are set in correspondence as shown in FIG. It is possible to try other associations. For example, when the correction amount a is set to be larger as the difference V _d is larger, it is conceivable to set a correspondence relationship as shown in FIG. By changing the correction amount a in accordance with the difference V _d, as well the engine output, it is possible to more slowly the change of the charging amount V of the battery 5.

In the embodiment described above, is adapted to implement a control of triplicate according to the sign of the difference V _d, as shown in step A50, A60 in FIG. 3, the magnitude relationship between the difference V _d and 0 However, instead of such a configuration, a configuration in which the magnitude relationship between the difference V _d and a predetermined minute value α is compared (for example, whether or not V _d > α, And it is determined whether or not V _d <−α.) Thereby, hunting of the control amount can be prevented, and the control stability in a state where the difference V _d = 0 can be improved.

In the above-described embodiment and its modification, the motor target torque T _m is calculated from the actual motor rotation speed N and the motor target output W _m, and the target motor rotation speed is controlled by the inverter 4. , it is conceivable to control the inverter 4 without calculating the target motor torque T _m. For example, as a general characteristic of the engine 2, a predetermined correspondence map can be created between the engine speed and the engine output. On the other hand, when the engine 2 and the motor 3 are connected on one axis as in the above-described embodiment, the engine speed and the motor speed are the same.

Therefore, to calculate the engine rotational speed for obtaining the target engine output W _t from the above correspondence map, by driving the motor 3 at a rotational speed identical to the rotational speed, the engine output does not vary, the operation of the engine 2 The state can be stabilized.
The effects as described above are not limited to the configuration in which the engine 2, the motor 3 and the hydraulic pump 1 are connected to one axis, and the ratio of the rotational speeds of the engine 2, the motor 3 and the hydraulic pump 1 is previously determined. If it is fixed or if a means for grasping the ratio of the respective rotational speeds is provided, the respective rotational speeds can be easily calculated, and the same effect can be obtained.

Also, those in the embodiment described above, the average value calculating portion 7a is adapted to calculate the arithmetic mean of the charging amount V as the average value V _a, method of calculating the average value V _a is not limited to this Instead, for example, it is conceivable to calculate using various methods such as a geometric average and a harmonic average.
The present invention can be applied to a parallel type hybrid work machine or a series / parallel type hybrid work machine in which a part of the actuator is motorized.

It is a typical lineblock diagram showing the whole output control device composition of a hybrid work machine as one embodiment of the present invention. It is a graph showing a relationship between a difference V _d and the correction amount a of the engine target output of the charge amount and the target charge amount of the battery in the device. It is a flowchart which shows the control content by this apparatus. 1 is a perspective view of a hydraulic excavator to which the present apparatus is applied. It is a flowchart which shows the control content as a modification. It is a graph which shows the modification of the correspondence shown in FIG.

Explanation of symbols

1 Hydraulic pump 2 Engine 3 Motor (motor / generator, electric motor)
4 Inverter 5 Battery 6 Battery voltmeter (Output variable detection means)
7 Controller 7a Average value calculation unit (average value calculation means)
7b Motor output setting section (output setting means)
8 Control valve 9 Actuator 10 Output control device 11 Operation lever (lever operation amount detection means)
12 Hydraulic gauge (Discharge pressure detection means)
DESCRIPTION OF SYMBOLS 13 Motor rotation speed sensor 20 Hydraulic excavator 21 Lower traveling body 22 Upper turning body 23 Working device 24 Engine room

Claims (11)

A hydraulic pump, an engine connected to the hydraulic pump so as to be able to transmit power, a motor capable of driving the hydraulic pump independently from the engine, and a motor connected to be able to generate electricity using the power of the engine; An output control device for a parallel hybrid work machine comprising a battery connected to transfer power to and from the motor;
Output variable detecting means for detecting a variable corresponding to the output state of the hybrid work machine;
An average value calculating means for calculating an average value of the variables detected by the output variable detecting means during a predetermined time set as a state average value;
An output control device for a hybrid work machine, comprising output setting means for setting the magnitude of the output of the engine in accordance with the state average value calculated by the average value calculation means. The output variable detection means detects the amount of charge of the battery as the variable,
The average value calculating means calculates the average value of the charge amount at the predetermined time,
The output setting means increases the output level of the engine when the average value of the charge amount is larger than a predetermined value, and the average value of the charge amount is larger than the predetermined value. 2. The output control apparatus for a hybrid work machine according to claim 1, wherein the output of the engine is reduced when the engine power is smaller. The output variable detection means detects the magnitude of the pump output of the hydraulic pump as the variable,
The average value calculating means calculates the average value of the pump output at the predetermined time,
2. The output control device for a hybrid work machine according to claim 1, wherein the output setting means sets an average value of the pump output as a magnitude of the output of the engine. The output variable detection means
A discharge pressure detecting means for detecting a discharge pressure of the hydraulic oil discharged from the hydraulic pump;
Lever operation amount detection means for detecting the operation amount of the operation lever of the hybrid work machine,
Based on the discharge pressure detected by the discharge pressure detection means and the operation amount detected by the lever operation amount detection means, the magnitude of the pump output of the hydraulic pump is calculated, The output control device for a hybrid work machine according to claim 3. The output variable detection means
A discharge pressure detecting means for detecting a discharge pressure of the hydraulic oil discharged from the hydraulic pump;
Swash plate angle detection means for detecting the swash plate angle of the hydraulic pump;
The size of the pump output of the hydraulic pump is calculated based on the discharge pressure detected by the discharge pressure detecting means and the swash plate angle detected by the swash plate angle detecting means. The output control device for a hybrid work machine according to claim 3. A pump output detecting means for detecting an output of the hydraulic pump as a work load of the hybrid work machine;
The output setting means subtracts the engine output from the output of the hydraulic pump detected by the pump output detection means to set the output of the motor. An output control device for a hybrid work machine according to claim 1. A rotation number detecting means for detecting the rotation number of the motor;
The output setting means divides the magnitude of the output of the motor by the rotation speed detected by the rotation speed detection means to set a target torque of the motor. Output control device for hybrid work machines. A rotational speed detection means for detecting the rotational speed of the motor;
Storage means for storing a correspondence relationship between the engine speed and the engine output;
The output setting means calculates the target engine speed calculated based on the state average value calculated by the average value calculating means and the correspondence stored in the storage means, as the target engine speed of the motor. The output control device for a hybrid work machine according to claim 1, wherein the output control device is set as follows. A hydraulic pump, an engine connected to the hydraulic pump so as to be able to transmit power, a motor capable of driving the hydraulic pump independently from the engine, and a motor connected to be able to generate electricity using the power of the engine; A parallel hybrid work machine output control method comprising a battery connected to transfer power to and from the motor,
An output variable detection step for detecting a variable corresponding to the output state of the hybrid work machine;
An average value calculating step for calculating an average value of the variables during a predetermined time set in advance as a state average value;
An output control method for a hybrid work machine, comprising: an output setting step of setting an output level of the engine in accordance with the state average value. In the output variable detection step, the amount of charge of the battery is detected as the variable,
In the average value calculating step, the average value of the charge amount in the predetermined time is calculated,
In the output setting step, when the average value of the charge amount is larger than a predetermined value, the output level of the engine is increased, and the average value of the charge amount is larger than the predetermined value. 10. The output control method for a hybrid work machine according to claim 9, wherein the output of the engine is reduced when the value is smaller. In the output variable detection step, the magnitude of the pump output of the hydraulic pump is detected,
In the average value calculating step, an average value of the pump output at the predetermined time is calculated,
10. The output control method for a hybrid work machine according to claim 9, wherein, in the output setting step, an average value of the pump output is set as a magnitude of the output of the engine.

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