JP5367639B2 - Control method of hybrid work machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately calculate the power in an input side of a hydraulic pump so as to control an engine load based on the power in an input side. <P>SOLUTION: In a hybrid working machine, a hydraulic pump 21 is driven by an output of an engine 30 and an output of a motor generator 34. The torque of the input side of the hydraulic pump 21 is calculated by estimated calculations. The power of the input side of the hydraulic pump 21 is calculated by multiplying the calculated torque by the rotational frequency of the hydraulic pump 21. Based on the calculated power, the output of the motor generator 34 is controlled. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a control method for a hybrid work machine, and more particularly to a control method for a hybrid work machine that generates hydraulic pressure by driving a pump by assisting an internal combustion engine with an electric motor.

  In general, a hybrid work machine drives a hydraulic pump with the output of an engine (internal combustion engine) and performs work with the generated hydraulic pressure. The engine is efficiently operated by assisting the engine with the electric motor. The electric motor is driven mainly by power from the battery. The battery is a charge / discharge type, and discharges and supplies electric power to the electric motor when assisting the engine. On the other hand, when the engine is not assisted, it is charged by electric power from a generator driven by the engine or regenerative electric power from a hydraulic load. As a result, the electric motor can be assisted while the battery is always kept charged to some extent.

  Thus, in the hybrid work machine, the engine can be assisted by the electric motor, so that the maximum output of the engine can be reduced and the engine can be made small. When an output larger than the maximum output of the engine is required for the hydraulic pump, the request can be met by assisting with the electric motor.

  By using the electric motor as a motor generator, the functions of the electric motor and the generator can be combined into one. In this case, it is necessary to control whether the assist function is executed as an electric motor or whether the power generation function is executed as a generator.

  Therefore, it has been proposed that the output of the hydraulic pump is obtained by calculation, and the obtained hydraulic pump output is compared with a threshold value to control whether the motor generator functions as an electric motor or as a generator ( For example, see Patent Document 1.)

JP 2004-11256 A

  The output of the hydraulic pump can be obtained by calculation from the pressure and flow rate of the hydraulic pump. This output corresponds to the power on the output side of the hydraulic pump. Therefore, conventionally, power on the output side of the hydraulic pump is obtained by calculation, and output control of the motor generator is performed based on this power.

  However, the input side power actually input to the hydraulic pump is not exactly equal to the output side power. Even if the output power of the hydraulic pump is known, the input side power must be accurately grasped. I can't. The power on the input side of the hydraulic pump is the sum of the power of the engine and the motor generator. The power on the output side of the hydraulic pump does not accurately reflect the sum of the load on the engine and the load on the motor generator.

  In order to operate the engine efficiently, it is necessary to accurately determine the load of the engine and adjust the output of the motor generator based on this. Therefore, in order to operate the engine efficiently, it is necessary to accurately determine the power on the input side of the hydraulic pump.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to accurately determine the power on the input side of the hydraulic pump and control the engine load based on the power on the input side.

  In order to achieve the above-mentioned object, according to the present invention, there is provided a control method for a hybrid work machine that drives a hydraulic pump with an engine output and an output of a motor generator, the torque on the input side of the hydraulic pump. Is calculated by estimation calculation, the calculated torque is multiplied by the rotational speed of the hydraulic pump to calculate the power on the input side of the hydraulic pump, and the output of the motor generator is controlled based on the calculated power. A control method for a hybrid work machine is provided.

In the control method for a hybrid work machine described above, the estimation calculation obtains a tilt angle ratio of the hydraulic pump based on a pump pressure detection value and a pump control current value, and determines the obtained tilt angle ratio and pump pressure detection. The torque is preferably calculated from the value. The mathematical formula for obtaining the tilt angle ratio of the hydraulic pump is preferably set based on a measured flow rate measured in advance, a rotational speed measured in advance, and a pressure measured in advance. The mathematical formula for obtaining the tilt angle ratio of the hydraulic pump may include a term representing the theoretical flow rate and a term representing the loss flow rate. The coefficient in the term representing the loss flow rate may be obtained from an actually measured flow rate measured in advance. The term representing the loss flow rate may include a plurality of flow loss factors. The plurality of flow rate loss coefficients are a first flow rate loss coefficient in a term representing a loss depending on a tilt angle ratio, pressure and rotational speed, and a first in a term representing a loss dependent on the rotational angle ratio and rotational speed. and second flow loss coefficient, a third flow loss coefficient in term representing losses depends on the rotational speed and pressure, of the fourth flow loss coefficient in term representing loss depends only on the rotational speed, the two It is good also as including the above .

  In the above-described hybrid work machine control method, it is preferable that the arithmetic expression for calculating the torque from the tilt angle ratio and the pump pressure detection value is a relational expression between the theoretical torque expression and the loss torque expression. The coefficient in the loss torque equation may be set based on a measured torque measured in advance. The loss torque equation may include a plurality of torque loss coefficients.

  According to the present invention, the power on the input side of the hydraulic pump can be accurately obtained, and the assist amount of the engine by the motor generator is controlled based on the power on the input side. For this reason, the load of the engine can be controlled with high accuracy, and the engine can always be maintained in a state of good operating efficiency.

2 is a control circuit of a hydraulic excavator applied to the present invention. It is a characteristic view which shows the relationship between the discharge pressure of a hydraulic pump and the discharge flow rate which are implement | achieved by the control circuit of FIG. It is a block diagram of the drive system of the hydraulic excavator provided with the control apparatus shown in FIG. It is a figure which shows a hydraulic load calculation algorithm. It is a graph which shows the relationship between the inclination-angle ratio of a variable displacement hydraulic pump, discharge pressure, and pump control current. It is a graph which shows the flow volume characteristic of a variable capacity type hydraulic pump. It is a graph which shows the torque characteristic of a variable displacement hydraulic pump. It is a figure which shows the hydraulic load calculation algorithm when a negative control pressure is considered. It is a graph which shows the flow volume characteristic of the variable displacement type hydraulic pump at the time of negative control. It is a graph which shows the negative control characteristic of tilt angle ratio. It is a figure which shows the hydraulic load estimation algorithm used when calculating the hydraulic pump output (power) of a shaft input side in the case of performing positive control. It is a figure which shows the hydraulic load calculation algorithm used when calculating the hydraulic pump output (power) of a shaft input side in the case of performing load sensing control.

  Embodiments of the present invention will be described with reference to the drawings.

  First, a control device for a hydraulic excavator as an example of a hybrid work machine to which the output limiting method according to the present invention is applied will be described. FIG. 1 is a block diagram showing a control circuit of a hydraulic excavator to which a control method according to the present invention is applied. The hybrid work machine to which the present invention is applied is not limited to a hydraulic excavator.

  First, the configuration of the hydraulic excavator control circuit shown in FIG. 1 will be described. Switching valves 22a, 22b, and 22c are connected to the oil passages of a variable displacement hydraulic pump (hereinafter simply referred to as a hydraulic pump) 21 driven by the engine motor 1, respectively. A pump discharge pressure sensor 23 is connected to the oil passage upstream of the switching valve 22a. The pump discharge pressure sensor 23 detects the discharge pressure of the hydraulic pump 21. Further, the oil passage on the downstream side of the switching valve 22 c is connected to the tank 25 via a negative control throttle valve (hereinafter referred to as a negative control throttle valve) 24.

  The variable displacement hydraulic pump 21 is, for example, a variable swash plate hydraulic pump, and the pump output can be changed by changing the angle of the swash plate. That is, the angle of the swash plate can be adjusted by changing the control current to the hydraulic pump 21, thereby changing the output of the hydraulic pump 21.

  A negative control sensor (hereinafter referred to as a negative control sensor) 26 is connected to the upstream side of the negative control throttle valve 24. The negative control sensor 26 is connected to the controller 2, detects the hydraulic pressure of the hydraulic flow path to each tank 25, and inputs a detection pressure signal to the controller 2.

  A negative controller (hereinafter referred to as “negative controller”) including the negative control throttle valve 24, the negative control sensor 26 and the controller 2 is a control system for reducing the loss of the discharge flow rate of the hydraulic pump 21 returning to the tank 25.

  In the controller 2, a mode switch 3 for switching to each work mode such as a heavy excavation mode (H mode), a standard excavation mode (S mode), a finishing excavation mode (L mode), and an engine speed are set. The throttle volume 4 is connected. Further, the electromagnetic proportional valve 5 and the discharge pressure sensor 23 are connected to the controller 2. The electromagnetic proportional valve 5 is connected to a regulator 27, and the regulator 27 controls the discharge flow rate of the hydraulic pump 21.

  Normally, a hydraulic excavator is equipped with a switching mechanism for switching to each work mode such as heavy excavation mode (H mode), standard excavation mode (S mode), and finish excavation mode (L mode). That is, the controller 2 appropriately switches to each work mode by the switching operation of the mode switch 3. By such a control circuit switching mechanism, the discharge flow rate of the hydraulic pump 21 is controlled by the regulator 27 so that the horsepower of the hydraulic excavator becomes constant. Furthermore, the electromagnetic proportional valve 5 changes the input horsepower of the hydraulic pump 21, and the controller 2 changes the rotation speed of the engine motor 1 to switch the above working modes, so that the discharge pressure of the hydraulic pump as shown in FIG. -The discharge flow rate characteristic (PQ characteristic) is realized.

  The negative control sensor 26 controls the pump discharge amount, and the pump discharge pressure sensor 23 detects the fluctuation of the pump discharge pressure P to control the discharge amount of the hydraulic pump 21.

  FIG. 3 is a block diagram of a drive system of a hydraulic excavator provided with the control device shown in FIG. An engine 30 that is an internal combustion engine and an assist motor 34 that is a motor generator are connected to a splitter 32 that is a power distributor. The engine 30, the assist motor 34, and the splitter 32 constitute the engine motor 1 shown in FIG. The variable displacement hydraulic pump 21 is connected to a splitter 32 and is driven by an output from the splitter 32 to discharge high-pressure hydraulic oil.

  The hydraulic oil discharged from the hydraulic pump 21 is sent to a controller valve 22 including switching valves 22a, 22b, and 22c shown in FIG. 1, and is supplied from the control valve 22 to a hydraulic load such as a hydraulic cylinder or a hydraulic motor. A pilot gear pump 21A for detecting and controlling the hydraulic pressure output is connected to the hydraulic pump 21. Based on the pressure P and discharge flow rate Q detected by the pilot gear pump 21A, the output (power) Wout on the shaft output side of the hydraulic pump 21 can be obtained.

  The assist motor 34 is connected via an inverter (INV) 36 to a battery 38 that is a storage battery. The assist motor 34 is driven by power supplied from the battery 38 and functions as an electric motor to assist the engine 30. Further, the assist motor 34 receives the power of the engine via the splitter 32 and functions as a generator to charge the battery 38. An electric load such as an electric motor or an electric actuator is connected to a battery 38 via an inverter (INV) 40 and operates by receiving supply of electric power from the battery 38.

  In the system shown in FIG. 3, the operation of the engine 30, the assist motor 34 and the hydraulic pump 21 is controlled by the controller 42. In particular, the controller 42 accurately calculates the output (power) Win on the shaft input side of the hydraulic pump 21 and controls the output (assist amount) of the assist motor 34. Thereby, the output of the engine 30 is always maintained at an appropriate value, and control is performed so that the operation of the engine does not become abnormal and is operated in an efficient range.

  Here, an algorithm used when the controller 42 calculates the output (power) Win on the shaft input side of the hydraulic pump 21 will be described with reference to FIG. FIG. 4 is a functional block diagram of a hydraulic load calculation algorithm used when calculating the output (power) Win on the shaft input side of the hydraulic pump 21.

  According to the algorithm shown in FIG. 4, the relationship between the discharge pressure P of the variable displacement hydraulic pump 21 and the tilt angle ratio X (a parameter representing the tilt of the tilt plate) is obtained, and the tilt angle of equal horsepower control is obtained. By determining the characteristics, the loss characteristics of the hydraulic pump 21 are determined. Then, the output torque T of the hydraulic pump 21 is obtained in consideration of the obtained loss characteristics of the hydraulic pump 21, and the output torque T is multiplied by the rotation speed N of the hydraulic pump 21, whereby the shaft input side of the hydraulic pump 21 is The output Win can be obtained with high accuracy.

  First, the tilt angle ratio calculation unit 50 obtains the tilt angle ratio X of the hydraulic pump 21 from the discharge pressure P of the hydraulic pump 21 and the pump control current I. The discharge pressure P of the hydraulic pump 21 is an actual measurement value, and the horsepower setting current I is an actual measurement value of a pump control current supplied to the hydraulic pump 21. Since the relationship between the tilt angle ratio X, the discharge pressure P of the hydraulic pump 21 and the pump control current I is represented by the map shown in FIG. 5, by using the values of the discharge pressure P and the pump control current I, The tilt angle ratio X can be obtained.

  The tilt angle ratio X calculated by the tilt angle ratio calculation unit 50 is output to the torque calculation unit 56. The torque calculator 56 calculates the torque T of the hydraulic pump 21 from the tilt angle ratio X calculated by the tilt angle ratio calculator 50 and the discharge pressure P. The torque T calculated by the torque calculation unit 56 takes into account the hydraulic pump efficiency η as described below, and is the torque on the shaft input side of the hydraulic pump 21. Therefore, the pump output calculation unit 58 can calculate the output (shaft input side) Win of the hydraulic pump 21 with high accuracy by multiplying the shaft input side torque T by the pump rotational speed N.

  Here, the calculation method of the tilt angle ratio X will be described in more detail.

  FIG. 6 is a graph showing a flow rate characteristic at a predetermined rotational speed of the variable displacement hydraulic pump. The hydraulic pump 21 normally has a flow rate characteristic indicated by the discharge pressure P and the pump limit current I shown in FIG. The flow rate of the variable displacement hydraulic pump can be expressed by a pump flow rate formula including a theoretical flow rate formula and a flow rate loss formula. Therefore, in the present invention, the flow characteristics shown in FIG. 6 are converted into the relationship between the tilt angle ratio X and the pump discharge pressure P shown in FIG.

The details of the pump flow rate type will be described below. The discharge flow rate Q of the variable displacement hydraulic pump theoretically includes the maximum displacement Vmax of the pump (the displacement when the tilt angle is maximum: cc / rev), the tilt angle ratio X (%) and the pump rotation speed. It can be obtained by multiplying N (rpm). However, the hydraulic pump cannot convert all applied power into a flow rate, resulting in a flow rate loss due to hydraulic leakage, mechanical friction, and the like. Accordingly, the actual discharge flow rate Q is obtained by subtracting the flow rate loss WQ from the theoretically obtained flow rate. The flow loss WQ depends on the rotation angle ratio X (%), the discharge pressure P (MPa), and the pump rotation speed (rpm). Considering the above, the equation for obtaining the discharge flow rate Q is as follows.

Q = Vmax · X · N / 1000−WQ (X, P, N) (1)
Theoretical flow rate type Flow loss type

In equation (1), the term Vmax · X · N / 1000 is the theoretical flow rate equation, and the term WQ (X, P, N) corresponds to the flow rate loss equation. The flow loss WQ can be expressed by a mathematical formula as follows by analysis and examination of actual measurement data.

WQ (X, P, N) = (Cv1, X, P + Cv2, X + Cv3, P + Cv4), N / 1000 (2)

In Expression (2), Cv1 is a first flow loss coefficient, Cv2 is a second flow loss coefficient, Cv3 is a third flow loss coefficient, and Cv4 is a fourth flow loss coefficient. The first flow rate loss coefficient Cv1 is a coefficient related to a loss term that depends on the rotation angle ratio X, the discharge pressure P, and the rotation speed N. The second flow rate loss coefficient Cv2 is a coefficient related to a loss term that depends on the rotation angle ratio X and the rotation speed N. The third flow rate loss coefficient Cv3 is a coefficient related to a loss term that depends on the discharge pressure P and the rotation speed N. The fourth flow loss coefficient Cv4 is a coefficient related to a loss term that depends only on the rotational speed N. These first to fourth flow loss factors Cv1, Cv2, Cv3, and Cv4 can be determined by analyzing using actual measurement data. Then, when equation (2) is substituted into equation (1) and the tilt angle ratio X is solved, the following equation (3) is obtained.

X = (Q ・ 1000 / N + Cv3 ・ P + Cv4) / (Vmax−Cv1 ・ P−Cv2) (3)

Then, in FIG. 6, by substituting the value of the discharge flow rate Q and the pump discharge pressure P of the variable displacement hydraulic pump shown as the flow rate characteristic at a predetermined rotational speed into the above formula (3), FIG. The pump characteristics of the tilt angle ratio X and the pump discharge pressure P shown can be obtained.

  Next, a method for calculating the torque τ by the torque calculator 56 will be described.

  The torque τ can also be obtained by using an approximate expression similarly to the discharge flow rate Q. FIG. 7 is a graph showing torque characteristics of the hydraulic pump. The torque characteristics of the hydraulic pump depend on the discharge pressure P and the pump control current I.

The torque characteristics shown in FIG. 7 are approximated and expressed as mathematical expressions as follows.

τ = Vmax / (2π) · X · P + Wτ (X, P) (4)
Theoretical torque formula Torque loss formula

In equation (4), the term Vmax / (2π) · X · P is a theoretical torque equation for theoretically obtaining torque, and the term Wτ (X, P) corresponds to the torque loss equation. The torque loss Wτ can be expressed by a mathematical formula as follows by analyzing and examining the measured data.

Wτ (X, P) = ( Ct1 · X 2 · P + Ct2 · X + Ct3 · P + Ct4) ··· (5)

In Expression (5), Ct1 is a first torque loss coefficient, Ct2 is a second torque loss coefficient, Ct3 is a third torque loss coefficient, and Ct4 is a fourth torque loss coefficient. The first torque loss coefficient Ct1 is a coefficient related to a loss term that depends on the square X ² of the tilt angle ratio and the discharge pressure P. The second torque loss coefficient Ct2 is a coefficient related to a loss term that depends on the tilt angle ratio X and the discharge pressure P. The third torque loss coefficient Ct3 is a coefficient related to a loss term that depends only on the discharge pressure P. The fourth torque loss coefficient Ct4 is a coefficient related to a loss term (steady loss term) that does not depend on the tilt angle ratio X or the discharge pressure. These first to fourth torque loss coefficients Ct1, Ct2, Ct3, and Ct4 can be determined by analyzing using actual measurement data.

  The pump output calculation unit 58 calculates the hydraulic pump output Win (shaft input side) by multiplying the torque τ calculated by the estimation calculation as described above by the pump rotational speed N. The hydraulic pump output (shaft input side) Win thus obtained corresponds to the power input to the hydraulic pump 21. Since the power input to the hydraulic pump 21 is the sum of the output of the engine 30 and the output of the assist motor 34, the hydraulic pump output (shaft input side) Win obtained by the sum of the output of the engine 30 and the output of the assist motor 34 is obtained. By controlling the output of the assist motor 30 in such a manner, the output of the engine 30 (that is, the load of the engine 30) can be controlled with high accuracy. Therefore, it is possible to control so that the load on the engine 30 is always an appropriate load, and the engine 30 can be operated in an efficient state.

  Although the negative control pressure (negative control pressure Pn) is not considered in the hydraulic load estimation algorithm described above, the hydraulic pump output (shaft input side) Win can be obtained more accurately by considering the negative control pressure Pn.

  FIG. 8 is a diagram showing a hydraulic load estimation algorithm used when calculating the output (power) Win on the shaft input side in consideration of the negative control pressure Pn. When the negative control pressure Pn is taken into consideration, the processing up to obtaining the tilt angle ratio X is different from the hydraulic load estimation algorithm shown in FIG. explain.

  When obtaining the tilt angle ratio X, the rotation angle ratio Xm obtained by calculation from the discharge pressure P and the pump control current I is obtained, and at the same time, the negative control tilt angle ratio Xn obtained from the negative control pressure Pn at the time of negative control. Is obtained by calculation. The negative control tilt angle ratio Xn is calculated by the negative control tilt angle ratio calculator 52.

  In order to obtain the mathematical formula for calculating the negative control tilt angle ratio Xn, first, the flow characteristics as shown in FIG. 9 obtained from the measured data of the negative control pressure Pn and the negative control discharge flow Qn are obtained. Then, the negative control characteristic of the tilt angle ratio as shown in FIG. 10 is obtained based on the flow rate characteristic equation (3). That is, the negative control tilt angle ratio Xn with respect to the discharge pressure Pn is calculated by substituting the discharge flow rate Qn and the discharge pressure Pn obtained from FIG. 9 into the flow rate characteristic equation (3).

  In the case of normal control in which negative control is not performed, the tilt angle ratio X of the hydraulic pump 21 is the tilt angle ratio Xm calculated by the tilt angle ratio calculation unit 50. On the other hand, while the negative control is being performed, the tilt angle ratio X of the hydraulic pump 21 becomes the negative control tilt angle ratio Xn calculated by the negative control control tilt angle ratio calculation unit 52. When the negative control is performed, the tilt angle ratio (negative control control tilt angle ratio Xn) is smaller than the normal tilt angle ratio Xm. Therefore, the negative control angle ratio Xn is compared with the normal inclination angle ratio Xm. When the negative control angle ratio Xn is smaller than the normal inclination angle ratio Xm, the negative control is in progress. It can be judged that there is.

  Therefore, the tilt angle ratio Xm calculated by the tilt angle ratio calculation unit 50 and the negative control tilt angle ratio Xn calculated by the negative control tilt angle ratio calculation unit 52 are input to the minimum selector 54. The minimum selector 54 selects the smaller one of the tilt angle ratio Xm and the negative control tilt angle ratio Xn, and outputs the smaller one to the torque calculator 56 as the tilt angle ratio X.

  As described above, the negative control tilt angle ratio Xn is used as the tilt angle ratio X when the negative control is performed by providing the negative control tilt angle calculation unit 52 and the minimum selector 54. It comes out. Thus, the torque calculation unit 56 can accurately calculate the torque τ by the estimation calculation even during the negative control.

  By calculating the torque τ on the input side of the hydraulic pump by estimation using the hydraulic load estimation algorithm shown in FIGS. 4 and 8 described above, the hydraulic pump output (shaft input side) Win can be calculated with high accuracy. . Then, by controlling the assist amount of the assist motor 34 based on the calculated hydraulic pump output (shaft input side) Win, the load on the engine 30 can always be made appropriate. Therefore, an overload on the engine 30 is prevented, and the vehicle can always be operated under efficient conditions.

  That is, the output of the assist motor 34 (when the electric state is a positive value) is controlled to be equal to the difference between the output (shaft input side) Win of the variable displacement hydraulic pump 21 and the output We of the engine 30. (Wa = Win-We). When the output Win of the hydraulic pump 21 becomes larger than the sum of the output We of the engine 30 and the output Wa of the assist motor 34 (WWin> We + Wa), an excessive load is applied to the engine 30. The maximum output Wamax is controlled to be larger than the difference between the output Win of the variable displacement hydraulic pump 21 and the maximum output Wemax of the engine (Wamax> Win−Wemax). Here, the maximum output Wamax of the assist motor 34 in the electric state is obtained by considering the maximum output Wbamax of the battery 38 and the output request Wout of the electric load in consideration of the maximum output Wbamax of the battery 38 when the output request Wout exists in the electric load. (Wamax <Wbmax−Wout).

  In the above description, the drive of the hydraulic pump 21 is controlled based on negative control (abbreviated negative control), but the drive control method of the hydraulic pump 21 includes positive control (abbreviated) in addition to negative control. , Positive control) and load control control.

  First, the case where the drive of the hydraulic pump 21 is controlled by positive control will be described. FIG. 11 is a diagram showing a hydraulic load estimation algorithm used for calculating the hydraulic pump output (power) Win on the shaft input side when the pump control circuit is configured to perform positive control. When the positive control is performed, the processing until the pump discharge amount V is obtained is different from the hydraulic load estimation algorithm in the case of performing the negative control shown in FIG. The process will be described.

When performing positive control, the hydraulic pump 21 according to the operation amount of each operation lever from the lever operation amounts θ ₁ , θ ₂ ,... Of the operation lever operated by the driver to drive the hydraulic drive unit. ejection amount _{V L1, V} L2 is required, ... are determined from the map showing the relationship between the lever operation amount theta _1, theta _2, the ... ejection amount _{V L1, V} L2, and ... in . Then, the sum of all the discharge amounts V _L1 , V _L2 ,... Becomes the required discharge amount V _L required for the hydraulic pump 21. By dividing the required discharge amount V _L at maximum capacity Vmax of the pump at the positive control control tilt angle ratio calculation unit 60, the positive control tilt angle ratio X _L against required discharge amount V _L is obtained.

Then, the pump tilting angle ratio X is any of the tilt angle ratio X to tilt angle ratio calculation unit 50 is calculated, and the positive control control tilting angle ratio X _L of the lever-regulated, pump control tilt angle ratio calculation unit 60 has calculated Or the smaller one. By using the tilt angle ratio X thus obtained for calculation of the hydraulic pump output (shaft output side) Wout and the calculation of the hydraulic pump efficiency ηo, the estimated hydraulic output (hydraulic pump) is calculated using the algorithm shown in FIG. Output (axis input side) Win can be calculated.

  Next, the case where the drive of the hydraulic pump 21 is controlled by load sensing control will be described. FIG. 12 is a diagram showing a hydraulic load calculation algorithm used for calculating the hydraulic pump output (power) Win on the shaft input side when the pump control circuit is configured to perform load sensing control. When the load sensing control is performed, the processing until obtaining the tilt angle ratio X is different from the hydraulic load estimation algorithm shown in FIG. explain.

  When performing load sensing control, the hydraulic pump discharge pressure P in FIG. 4 is set to a value obtained by adding the differential pressure ΔP to the maximum load pressure Pmax. The differential pressure ΔP is added in order to give a certain margin to the discharge amount of the pump, and may be a constant value or a variable value. The tilt angle ratio X is determined based on the characteristics of the tilt angle ratio X of the hydraulic pump 21 and the pump discharge pressure P shown in FIG. It is obtained from the pump current (control current) I supplied to the pump 21. The tilt angle ratio X thus obtained is used for calculation of the hydraulic pump output (shaft output side) Wout and the calculation of the hydraulic pump efficiency ηo, thereby using the algorithm shown in FIG. Output (axis input side) Win can be calculated.

DESCRIPTION OF SYMBOLS 1 Engine motor 2 Controller 3 Mode selector 4 Throttle volume 5 Electromagnetic proportional valve 21 Hydraulic pump 21A Pilot gear pump 22 Controller valve 22a, 22b, 22c Switching valve 23 Pump discharge pressure sensor 24 Negative control throttle valve (negative control throttle valve)
25 Tank 26 Negative control sensor (negative control sensor)
27 Regulator 30 Engine 32 Splitter 34 Assist motor 36, 40 Inverter 38 Battery 42 Controller 50 Tilt angle ratio calculator 52 Negative control tilt angle ratio calculator 54 Minimum selector 56 Torque calculator 58 Pump output calculator 60 Positive control tilt angle Ratio calculator

Claims (11)

A control method for a hybrid work machine that drives a hydraulic pump with the output of an engine and the output of a motor generator,
Calculate the torque on the input side of the hydraulic pump by estimation calculation,
Multiply the calculated torque by the number of rotations of the hydraulic pump to calculate the power on the input side of the hydraulic pump,
A control method for a hybrid work machine, wherein the output of the motor generator is controlled based on the calculated power. A control method for a hybrid work machine according to claim 1,
The estimation calculation calculates a tilt angle ratio of the hydraulic pump based on a pump pressure detection value and a pump control current value, and calculates a torque from the determined tilt angle ratio and the pump pressure detection value. To control a hybrid hybrid work machine. A control method for a hybrid work machine according to claim 2,
The formula for obtaining the tilt angle ratio of the hydraulic pump is set based on a measured flow rate measured in advance, a rotation speed measured in advance, and a pressure measured in advance. Control method. A control method for a hybrid work machine according to claim 2,
The formula for calculating the tilt angle ratio of the hydraulic pump includes a term representing a theoretical flow rate and a term representing a loss flow rate. A control method for a hybrid work machine according to claim 4,
A control method for a hybrid work machine, wherein a coefficient in a term representing the loss flow rate is obtained from a measured flow rate measured in advance. A control method for a hybrid work machine according to claim 4,
The term representing the loss flow rate includes a plurality of flow loss coefficients. A hybrid work machine according to claim 6,
The plurality of flow rate loss coefficients are a first flow rate loss coefficient in a term representing a tilt angle ratio, a loss dependent on pressure and a rotational speed, and a second in a term representing a loss dependent on the rotational angle ratio and the rotational speed. Two or more of the flow loss coefficient, the third flow loss coefficient in the term representing the loss depending on the pressure and the rotational speed, and the fourth flow loss coefficient in the term representing the loss dependent only on the rotational speed A control method for a hybrid work machine, comprising: A control method for a hybrid work machine according to claim 2,
A control method for a hybrid work machine, wherein an arithmetic expression for calculating torque from a tilt angle ratio and a pump pressure detection value is a relational expression between a theoretical torque expression and a loss torque expression. A method for controlling a hybrid work machine according to claim 8,
The coefficient in the loss torque formula is set based on the actually measured torque measured in advance, and the control method of the hybrid type work machine. A method for controlling a hybrid work machine according to claim 8,
The method of controlling a hybrid work machine, wherein the loss torque equation includes a plurality of torque loss coefficients. A control method for a hybrid work machine according to claim 10,
The plurality of torque loss coefficients in a term that depends on a product of a first torque loss coefficient and a tilt angle ratio and a pressure in a term that represents a loss that depends on a product of the square of the tilt angle ratio and a pressure. includes a second torque loss factor, and the third torque loss factor in the term depending on the pressure, of the fourth torque loss factor in terms that do not depend on the pressure in the tilt angle ratio, two or more A control method for a hybrid type work machine.

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