JP6286282B2 - Hydraulic regeneration device and construction machine equipped with the same - Google Patents

Description

  The present invention relates to a hydraulic regeneration device for regenerating energy of return oil derived from a hydraulic actuator and a construction machine including the same.

  Conventionally, a construction provided with a hydraulic pump driven by an engine, a hydraulic actuator operated by hydraulic oil from the hydraulic pump, and a regenerative motor and accumulator for regenerating the energy of the hydraulic oil derived from the hydraulic actuator The machine is known.

  The regenerative motor is connected to the output shaft of the engine. When the return oil is supplied to the regenerative motor and the regenerative motor is driven, the power of the engine (power for driving the hydraulic pump) can be assisted.

  The accumulator accumulates pressure with the return oil, and drives the hydraulic actuator by releasing the pressure as necessary.

  For example, a work machine described in Patent Document 1 includes a pump motor (regenerative motor) connected to a head side oil passage of a boom cylinder (hydraulic actuator), and an accumulator connected to the head side oil passage via the pump motor. It has.

  According to this work machine, the hydraulic oil derived from the boom cylinder during the boom lowering operation is guided to the accumulator via the pump motor, and the accumulator is accumulated by the hydraulic oil increased in pressure by the pump motor.

  On the other hand, when it is difficult to accumulate the pressure in the accumulator during the boom lowering operation, the pump motor operates as a motor with hydraulic oil derived from the boom cylinder, thereby assisting the power of the engine.

JP 2010-84888 A

  However, in the work machine described in Patent Document 1, since the pump motor and the accumulator are connected in series to the head-side oil passage of the boom cylinder, all of the hydraulic oil guided from the boom cylinder to the accumulator has the pump motor. Via.

  Therefore, the capacity of the pump motor must be set large assuming a relatively large flow rate of return oil derived from the boom cylinder.

  As a result, there is a problem that the pump motor is increased in size and a loss (hereinafter referred to as follow loss) due to the pump motor being driven by the engine in a state where the return oil is not supplied is increased.

  An object of the present invention is to provide a hydraulic regeneration device capable of suppressing an increase in size of a regenerative motor and reducing accompanying loss, and a construction machine including the same.

In order to solve the above-mentioned problems, the present invention is a hydraulic regenerative device comprising an engine, a hydraulic pump driven by the engine, a hydraulic actuator operated by hydraulic oil from the hydraulic pump, and the hydraulic actuator A variable capacity regenerative motor that is drivable by being supplied with the returned return oil and that is connected to the output shaft of the engine so as to assist the power of the engine by this driving, and the hydraulic actuator An accumulator capable of accumulating pressure from the return oil from the engine, and the regenerative motor and the accumulator are connected in parallel to a port of the hydraulic actuator from which the return oil is derived. The amount of the return oil distributed to the motor and the accumulator can be adjusted. And adjusting means, when the predetermined regeneration condition as a condition for regenerating the energy of the return oil is established, so that preferentially the return oil is supplied to the regenerative motor than the accumulator And a controller for controlling the distribution adjusting means , wherein the controller derives from the hydraulic actuator a flow rate of return oil that exceeds the absorbable flow rate that can be absorbed by the regenerative motor adjusted to a preset set capacity. If it is, the absorption flow rate of the return oil is supplied to the regenerative motor, and at least part of the return oil in excess of the absorption flow rate is that control the distribution adjustment means so as to be supplied to the accumulator Provide a hydraulic regeneration device.

  According to the present invention, it is possible to relatively reduce the return oil supplied to the regenerative motor by increasing the ratio of the return oil distributed to the accumulator when a large amount of return oil is present.

  Therefore, unlike the conventional technology in which all of the return oil supplied to the accumulator passes through the regenerative motor, the maximum capacity of the regenerative motor can be kept small, thereby suppressing the increase in the size of the regenerative motor and accompanying loss. Can be reduced.

  Here, when a regeneration condition set in advance as a condition for regenerating the energy of the return oil is satisfied, the ratio of the return oil to be distributed to the regeneration motor and the accumulator is determined by the distribution adjustment unit. Depending on the control, if the return oil is supplied preferentially to the accumulator rather than the regenerative motor, the regenerative efficiency may decrease.

  Specifically, when the accumulator is accumulated by the return oil, not only the energy loss of the accumulator at the time of accumulating, but also the energy loss of the hydraulic actuator driven by the pressure released from the accumulator thereafter occurs.

Therefore, according to the present invention, when the regeneration condition is satisfied, the hydraulic regeneration device controls the distribution adjusting unit so that the return oil is supplied to the regeneration motor with priority over the accumulator. A controller is further provided .

According to the present invention , since the regenerative motor is preferentially driven by the return oil derived from the hydraulic actuator, it is possible to relatively reduce the energy loss during regeneration by the accumulator described above, thereby improving the regeneration efficiency. Can be suppressed.

Specifically, the controller returns the absorbable flow rate when a return oil having a flow rate exceeding the absorbable flow rate that can be absorbed by the regenerative motor adjusted to a preset set capacity is derived from the hydraulic actuator. The distribution adjusting means is controlled so that oil is supplied to the regenerative motor and at least a part of the return oil exceeding the absorbable flow rate is supplied to the accumulator .

  Here, if the “set capacity” is set so that the drive efficiency of the regenerative motor is greater than or equal to the preset efficiency, the accumulator will restore the energy of the remaining return oil while regenerating with high efficiency by the regenerative motor. Can be regenerated.

  On the other hand, if the “set capacity” is set to the maximum capacity of the regenerative motor, energy loss during regeneration by the accumulator described above can be reduced as much as possible.

  That is, the “set capacity” can be appropriately set in consideration of the regeneration efficiency.

  In the hydraulic regeneration device, the hydraulic regeneration device further includes a tank connected in parallel with the regeneration motor and the accumulator to a port of the hydraulic actuator from which the return oil is derived, The ratio of the return oil distributed to the regenerative motor, the accumulator, and the tank can be adjusted, and the controller supplies return oil other than the return oil supplied to the regenerative motor and the accumulator among the return oil. It is preferable to control the distribution adjusting means to supply the tank.

  According to this aspect, portions of the return oil other than those guided to the regenerative motor and the accumulator can be collected in the tank.

  Here, the speed of the engine may increase due to the driving of the regenerative motor by supplying the return oil, and in this case, the driving efficiency of the engine may be reduced.

  Therefore, when the speed of the engine increases due to the driving of the regenerative motor due to the supply of the return oil, the controller distributes the return oil to the regenerative motor so as to prevent an increase in the speed of the engine. It is preferable to reduce the ratio.

  According to this aspect, by reducing the ratio of the return oil distributed to the regenerative motor, it is possible to regenerate the energy of the return oil while preventing a decrease in engine drive efficiency.

  Specifically, when only the hydraulic pump is provided as the load for the engine, the engine torque is mainly determined by the pump torque by the drive of the hydraulic pump, so the drive torque by the drive of the regenerative motor is the pump. It can be considered that the engine speed increases when the torque is exceeded.

  Therefore, when the drive torque due to the drive of the regenerative motor exceeds the pump torque due to the drive of the hydraulic pump, the controller returns oil distributed to the regenerative motor so that the drive torque is less than or equal to the pump torque. The ratio of can be lowered.

  According to this aspect, it is possible to prevent an increase in the engine speed by using the pump torque and the drive torque without detecting the actual engine speed.

  When the engine is provided with a plurality of loads, the ratio of the return oil distributed to the regenerative motor is reduced so that the drive torque of the regenerative motor is smaller than the total torque generated by driving these loads. The increase in engine speed can be prevented.

Further, the present invention is a hydraulic regenerative device, comprising an engine, a hydraulic pump driven by the engine, a hydraulic actuator operated by hydraulic oil from the hydraulic pump, and return oil derived from the hydraulic actuator. A variable capacity regenerative motor connected to the output shaft of the engine so as to assist the power of the engine by this driving and a return oil from the hydraulic actuator for accumulating pressure. The regenerative motor and the accumulator are connected in parallel to a port of the hydraulic actuator from which the return oil is derived, and the hydraulic regenerative device is distributed to the regenerative motor and the accumulator Distribution adjusting means capable of adjusting the ratio of the return oil to be returned, and the return oil The distribution adjusting means is configured so that the return oil is preferentially supplied to the regenerative motor over the accumulator when a regenerative condition set in advance as a condition for regenerating the energy of oil is satisfied. and a controller for controlling said and in accordance with the driving of the regenerative motor generator connectable to the regenerating motor so as to have been the generator, further wherein the controller, the regenerative motor due to the return oil is supplied When the speed of the engine is increased by driving the engine , a hydraulic regenerative device is provided that can control the generator so that power generation is performed with a power generation torque that can prevent an increase in the speed of the engine.

According to the present invention, it is possible to relatively reduce the return oil supplied to the regenerative motor by increasing the ratio of the return oil distributed to the accumulator when a large amount of return oil is present.

Therefore, unlike the conventional technology in which all of the return oil supplied to the accumulator passes through the regenerative motor, the maximum capacity of the regenerative motor can be kept small, thereby suppressing the increase in the size of the regenerative motor and accompanying loss. Can be reduced.

According to this aspect, since the regenerative motor is preferentially driven by the return oil derived from the hydraulic actuator, it is possible to relatively reduce the energy loss during regeneration by the accumulator described above, thereby improving the regeneration efficiency. Can be suppressed.

Furthermore, according to the present invention , it is possible to prevent a reduction in engine driving efficiency while maintaining a high regenerative efficiency of the regenerative motor by maintaining the flow rate of the return oil supplied to the regenerative motor at an absorbable flow rate. .

Therefore, according to the present invention , the energy of the return oil can be regenerated more effectively.

  Specifically, when the driving torque due to the driving of the regenerative motor exceeds the pumping torque due to the driving of the hydraulic pump, the controller generates power with the power generation torque equal to or greater than the torque obtained by subtracting the pump torque from the driving torque. The generator can be controlled to do so.

  According to this aspect, it is possible to prevent an increase in the engine speed by using the pump torque and the drive torque without detecting the actual engine speed.

  Further, the present invention is a construction machine, which is a construction machine, and includes a machine body, a boom attached to the machine body so as to be able to perform a raising operation and a lowering operation, and the hydraulic regeneration device, The hydraulic actuator supplies power for the raising operation and the lowering operation to the boom, and the distribution adjusting means sets a ratio of return oil distributed to the regenerative motor and the accumulator during the lowering operation of the boom. Providing construction machinery that is adjustable.

  According to the present invention, the potential energy of the boom during the boom lowering operation can be effectively regenerated by the regenerative motor and the accumulator.

  According to the present invention, the regenerative motor can be increased in size and accompanying loss can be reduced.

1 is a side view showing an overall configuration of a hydraulic excavator according to a first embodiment of the present invention. 1 is a circuit diagram showing a hydraulic regeneration device according to a first embodiment of the present invention. FIG. 3 is a first half of a flowchart showing processing executed by the controller shown in FIG. 2. FIG. FIG. 3 is a second half of a flowchart showing processing executed by the controller shown in FIG. 2. It is a circuit diagram which shows the hydraulic regeneration apparatus which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the process performed by the controller shown in FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

<First Embodiment (FIGS. 1 to 4)>
Referring to FIG. 1, a hydraulic excavator 1 as an example of a construction machine according to a first embodiment of the present invention includes a lower traveling body 2 having a crawler 2a, and an upper portion provided on the lower traveling body 2 so as to be able to turn. A revolving body 3, a work attachment 4 attached to the upper revolving body 3 so as to be displaceable, and a hydraulic regeneration device 5 shown in FIG. 2 are provided. The lower traveling body 2 and the upper swing body 3 correspond to a machine body to which a later-described boom 6 is attached.

  The work attachment 4 is attached to the upper swing body 3 so as to be able to be raised and lowered, an arm 7 is rotatably attached to the tip of the boom 6, and is rotatably attached to the tip of the arm 7. The bucket 8 is provided.

  The work attachment 4 includes a boom cylinder 9 that supplies power for raising and lowering the boom 6, an arm cylinder 10 that rotationally drives the arm 7, and a bucket that rotationally drives the bucket 8. And a cylinder 11.

  With reference to FIG. 2, the hydraulic regenerative device 5 is for regenerating the energy of the return oil derived from the boom cylinder 9 (an example of a hydraulic actuator) when the boom 6 is lowered.

  Specifically, the hydraulic regeneration device 5 includes an engine 14, a variable displacement hydraulic pump 15 driven by the engine 14, a boom cylinder 9 and an arm cylinder 10 that are operated by hydraulic oil from the hydraulic pump 15, and a boom cylinder. 9, a boom side circuit 16 for controlling the driving of the arm 9, an arm side circuit 17 for controlling the driving of the arm cylinder 10, and a controller 18 for controlling the regeneration of the return oil in the boom side circuit 16.

  The hydraulic pump 15 is connected to the output shaft of the engine 14.

  The arm side circuit 17 includes a control valve 17a for controlling the supply and discharge of hydraulic oil to and from the arm cylinder 10, an operating means 17b for operating the control valve 17a, and the arm cylinder 10 is reduced when the operating means 17b is not operated. And a lock valve 17c for locking the operation.

  The boom side circuit 16 is connected to the hydraulic pump 15 in parallel with the arm side circuit 17.

  Further, the boom side circuit 16 includes a control valve 19 for controlling supply and discharge of hydraulic oil to and from the boom cylinder 9, an operation means 20 for operating the control valve 19, and the boom cylinder 9 when the operation means 20 is not operated. A lock valve 21 that locks down the shrinkage, a regenerative motor 22, an accumulator 23, and a tank 24 connected in parallel to the head side port (not shown) of the boom cylinder 9, and the supply amount of hydraulic oil to these Motor control valve 25, pressure accumulation control valve 26, and discharge control valve 28, and a discharge control valve 27 for controlling the flow rate of hydraulic oil discharged from the accumulator 23. .

  The control valve 19 includes a neutral position shown in the figure, a boom raising position for performing the raising operation by the boom 6 (left side position in the figure), and a boom lowering position for performing the lowering operation by the boom 6 (right side in the figure). It is possible to switch between these positions.

  When the control valve 19 is switched to the boom raising position, the hydraulic pump 15 and the head side oil passage R2 of the boom cylinder 9 are connected, and the rod side oil passage R1 of the boom cylinder 9 and the tank are connected. On the other hand, when the control valve 19 is switched to the boom lowering position, the hydraulic pump 15 and the rod side oil passage R1 are connected and the head side oil passage R2 is closed.

  The operation means 20 includes a remote control valve for supplying pilot pressure to the control valve 19 and an operation lever for operating the remote control valve.

  The regenerative motor 22 can be driven when supplied with return oil derived from the boom cylinder 9 and is connected to the output shaft of the engine 14 so as to assist the power of the engine 14 by this driving. Specifically, the regenerative motor 22 is a variable displacement hydraulic motor and has a regulator 22a for adjusting the capacity. A capacity of the regenerative motor 22 can be adjusted by inputting a command from the controller 18 described later to the regulator 22a.

  Further, the regenerative motor 22 is provided in a motor oil passage R3 connected to the head side oil passage R2 of the boom cylinder 9. A motor control valve 25 is provided upstream of the regenerative motor 22 in the motor oil passage R3. The motor control valve 25 is an electromagnetic flow control valve capable of controlling the flow rate of hydraulic oil supplied to the regenerative motor 22 in accordance with a command from the controller 18 described later. The motor control valve 25 may be an electromagnetic on-off valve capable of opening and closing the motor oil passage R3.

  The accumulator 23 can accumulate pressure with return oil from the boom cylinder 9.

  The accumulator 23 is provided in an accumulator oil passage R4 connected in parallel to the motor oil passage R3 with respect to the head side oil passage R2 of the boom cylinder 9. A pressure accumulation control valve 26 is provided on the upstream side of the accumulator 23 in the accumulator oil passage R4, and a discharge control valve 27 is provided on the downstream side of the accumulator 23. The accumulator control valve 26 is an electromagnetic flow control valve capable of controlling the flow rate of hydraulic oil supplied to the accumulator 23 in accordance with a command from the controller 18. The discharge control valve 27 is an electromagnetic flow control valve capable of controlling the flow rate of the hydraulic oil discharged from the accumulator 23 in accordance with a command from the controller 18. Since the downstream end of the accumulator oil path R4 is connected to a position between the motor control valve 25 and the regenerative motor 22 in the motor oil path R3, the regenerative motor 22 is opened when the discharge control valve 27 is opened. To drive.

  The tank 24 is for collecting surplus return oil other than the portion supplied to the regenerative motor 22 and the accumulator 23 among the return oil from the boom cylinder 9.

  The tank 24 is provided in a tank oil passage R5 connected in parallel with the motor oil passage R3 and the accumulator oil passage R4 with respect to the head side oil passage R2 of the boom cylinder 9. A discharge control valve 28 is provided on the upstream side of the tank 24 in the tank oil passage R5. The discharge control valve 28 is an electromagnetic flow control valve capable of controlling the flow rate of the hydraulic oil guided to the tank 24 in accordance with a command from the controller 18.

  A boost check valve 29 is provided at a position between the tank 24 and the discharge control valve 28 in the tank oil passage R5. The boost check valve 29 is for raising a back pressure in order to supply hydraulic oil to the rod side oil passage R1 through the supply oil passage R6 during the boom lowering operation. The supply oil path R6 connects the position between the discharge control valve 28 and the boost check valve 29 in the tank oil path R5 and the rod side oil path R1. The check valve 30 provided in the replenishing oil path R6 is for restricting the flow of hydraulic oil from the head side oil path R2 to the tank oil path R5 during the boom raising operation.

  The motor control valve 25, the pressure accumulation control valve 26, and the discharge control valve 28 correspond to distribution adjusting means that can adjust the ratio of return oil distributed to the regenerative motor 22, the accumulator 23, and the tank 24. Since the flow rate of the return oil supplied to the regenerative motor 22 can be adjusted by adjusting the capacity of the regenerative motor 22, the motor control valve 25 can be omitted in the distribution adjusting means. In this case, the closing function of the motor control valve 25 can be realized by minimizing the capacity of the regenerative motor 22.

  Further, the hydraulic regenerative device 5 includes a discharge pressure sensor D1 that can detect the discharge pressure of the hydraulic pump 15, a head pressure sensor D2 that can detect the pressure of the return oil from the boom cylinder 9, and an operation accumulated in the accumulator 23. A pressure accumulation sensor D3 capable of detecting the pressure of the oil; an operation amount sensor D4 capable of detecting an operation amount and an operation direction of the operation means 17b; an operation amount sensor D5 capable of detecting an operation amount and an operation direction of the operation means 20; A rotation speed detector D6 capable of detecting the rotation speed of the engine 14 is provided.

  The head pressure sensor D2 is provided in the head side oil passage R2.

  The pressure accumulation sensor D3 is provided at a position between the pressure accumulation control valve 26 and the accumulator 23 in the accumulator oil passage R4.

  The operation amount sensor D4 includes an encoder or the like that can detect the operation amount and the operation direction of the operation lever of the operation means 17b. Similarly, the operation amount sensor D5 is configured by an encoder or the like that can detect the operation amount and the operation direction of the operation lever of the operation means 20. The operation amount sensors D4 and D5 may detect the operation amount and the operation direction of the operation means 17b and 20 as the magnitude of the pilot pressure for both ports of the control valves 17a and 19.

  The detection values by the sensors D1 to D6 described above are input to the controller 18 as electrical signals.

  The controller 18 outputs a command to the control valves 25, 26, 28 and the regulator 22 a of the regenerative motor 22 based on the detection values input from the sensors D 1 to D 6.

  Further, the controller 18 controls the boom side circuit 16 so that at least the energy of the return oil derived from the boom cylinder 9 is regenerated by the regenerative motor 22 when a preset regenerative condition is satisfied. That is, the controller 18 controls the boom side circuit 16 so that the return oil from the boom cylinder 9 is preferentially supplied to the regenerative motor 22 over the accumulator 23 when the regenerative condition is satisfied.

  Here, the regeneration condition is set to be established when the boom 6 is lowered by its own weight, that is, when the potential energy of the boom 6 can be regenerated.

  Hereinafter, processing executed by the controller 18 will be described with reference to FIGS.

  When processing by the controller 18 is started, it is first determined whether or not a lever operation for lowering the boom 6 by the operation means 20 has been performed based on a detection value from the operation amount sensor D5 (step S1).

  If it is determined in step S1 that the lever operation for lowering the boom 6 has been performed, it is determined whether or not the regeneration condition is satisfied (step S2). Specifically, in step S2, when the condition of (Pr × Ar) <(Ph × Ah) is satisfied and the pressure in the head side chamber of the boom cylinder 9 exceeds a preset pressure, regeneration is performed. It is determined that the condition is met. Here, Pr is the pressure in the rod side chamber of the boom cylinder 9 and is detected by the discharge pressure sensor D1. Ar is a cross-sectional area of the rod side chamber of the boom cylinder 9 and is stored in advance. Ph is the pressure in the head side chamber of the boom cylinder 9 and is detected by the head pressure sensor D2. Ah is a cross-sectional area of the head side chamber of the boom cylinder 9 and is stored in advance. The “preset pressure” is set in advance as a pressure necessary for rotating the regenerative motor 22.

  If it is determined in step S2 that the regenerative condition is satisfied, a boom lowering target flow rate is calculated using the following equation (1) (step S3). The boom lowering target flow rate is the flow rate of the return oil that should be derived from the boom cylinder 9 according to the operation amount of the operation means 20.

Q = Cv × A × √ (P) (1)
In step S3, a virtual opening preset in relation to the operation amount of the operating means 20 is substituted as A (mm ² ) for the expression (1), and the pressure of the head side oil passage R2 of the boom cylinder 9 is set to P By substituting as (MPa), Q [l / min] as a boom lowering target flow rate is calculated. Cv is a preset coefficient. Hereinafter, the boom lowering target flow rate is denoted as Q_MO_target.

  Next, it is determined whether the boom lowering target flow rate is larger than the resorbable flow rate of the regenerative motor 22 (step S4). Here, the absorbable flow rate is determined by a preset set capacity (maximum capacity in the present embodiment) of the regenerative motor 22 and the rotational speed of the engine 14.

  If it is determined in step S4 that the boom lowering target flow rate is larger than the absorbable flow rate, that is, if there is excess return oil for the regenerative motor 22, the capacity of the regenerative motor 22 is temporarily set to a set capacity ( Step S5: This capacity is referred to as motor virtual capacity in step S6).

  Next, it is determined whether or not the pump torque due to the drive of the hydraulic pump 15 is larger than the motor virtual torque (drive torque) due to the drive of the regenerative motor 22 when the capacity of the regenerative motor 22 is set to the motor virtual capacity. (Step S6). Here, the pump torque of the hydraulic pump 15 is determined by the capacity of the hydraulic pump 15 and the discharge pressure, and the capacity of the hydraulic pump 15 is set in advance in relation to the operation amounts of the operation means 17b and 20. .

  If it is determined in step S6 that the pump torque of the hydraulic pump 15 is greater than the virtual motor torque, that is, if it is determined that an increase in the speed of the engine 14 can be avoided even if the motor virtual torque is set, regeneration is performed. The command capacity of the motor 22 is set to the set capacity (step S7). In step S7, the command opening area of the motor control valve 25 is set to fully open.

  On the other hand, when it is determined in step S4 that the boom lowering target flow rate is equal to or lower than the absorbable flow rate, that is, when all of the return oil can be supplied to the regenerative motor 22, the capacity of the regenerative motor 22 is reached. Is set as the boom reference capacity (step S8: this capacity is referred to as motor virtual capacity in step S9). Here, the boom reference capacity is the capacity of the regenerative motor 22 for flowing the boom lowering target flow rate, and is determined by the boom lowering flow rate and the engine speed.

  Next, it is determined whether or not the pump torque due to the drive of the hydraulic pump 15 is larger than the motor virtual torque (drive torque) due to the drive of the regenerative motor 22 when the capacity of the regenerative motor 22 is set to the motor virtual capacity. (Step S9).

  If it is determined in step S9 that the pump torque of the hydraulic pump 15 is greater than the virtual motor torque, that is, if it is determined that an increase in the speed of the engine 14 can be avoided even when the motor virtual torque is set, regeneration is performed. The command capacity of the motor 22 is set to the boom reference capacity (step S10). In step S10, the command opening area of the motor control valve 25 is set to fully open.

  On the other hand, if it is determined in step S6 and step S9 that the pump torque of the hydraulic pump 15 is equal to or less than the virtual motor torque, the command capacity of the regenerative motor 22 is set to the torque reference capacity (step S11). Here, the torque reference capacity is the capacity of the regenerative motor 22 for regenerating return oil within the range of the pump torque of the hydraulic pump 15, and the pump torque of the hydraulic pump 15 is set in the head side oil passage R2 of the boom cylinder 9. It is obtained by dividing by the pressure. When there is a margin in the accumulator capacity of the accumulator 23, the command capacity of the regenerative motor 22 can be set below the torque reference capacity. In step S11, the command opening area of the motor control valve 25 is set to fully open.

  When the command capacity of the regenerative motor 22 is set to the set capacity in step S7 and when the flow rate of the return oil supplied to the regenerative motor 22 is limited in step S11, there is surplus return oil for the regenerative motor 22. . Therefore, in order to regenerate surplus return oil by the accumulator 23, in step S12, the flow rate of the remaining return oil other than the return oil supplied to the regenerative motor 22 and the regenerative flow rate of the accumulator 23 (hereinafter, regenerative is possible). (Referred to as flow rate).

  Specifically, the flow rate of the remaining return oil can be obtained by subtracting the flow rate of the regenerative motor 22 from the boom lowering target flow rate calculated in step S3. Further, by substituting the maximum opening area of the pressure accumulating control valve 26 as A and substituting the difference pressure obtained by subtracting the pressure of the accumulator 23 from the pressure in the head side oil passage R2 as P in the above equation (1). The regenerative flow rate Q can be calculated.

  Next, it is determined whether or not the regenerative flow rate is greater than 0, that is, whether or not regeneration is possible by the accumulator 23 (step S13). Here, when the pressure in the accumulator 23 is higher than the pressure in the head-side oil passage R2, it is determined that regeneration is not possible. In this case, the command opening area of the pressure accumulation control valve 26 is 0 (that is, fully closed). ) Is set (step S14).

  On the other hand, if it is determined in step S13 that regeneration is possible, it is determined whether the flow rate of the remaining return oil is larger than the regenerative flow rate (step S15). Here, if it is determined that the flow rate of the remaining return oil is larger than the regenerative flow rate, the command opening area of the pressure accumulation control valve 26 is maximized (fully opened) in order to supply the regenerative flow rate return oil to the accumulator 23. (Step S16).

  When regeneration by the accumulator 23 is not performed in step S14 and when return oil having a regenerative flow rate is supplied to the accumulator 23 in step S16, surplus return oil exists in the regeneration motor 22 and the accumulator 23. Therefore, in step S <b> 17, a command opening area of the discharge control valve 28 for collecting excess return oil in the tank 24 is set. Specifically, for the above formula (1), the flow rate obtained by subtracting the regenerative flow rate from the remaining return oil flow rate is substituted as Q, and the pressure in the head side oil passage R2 is substituted as P, thereby discharging. The opening area A of the control valve 28 can be calculated.

  On the other hand, if it is determined in step S15 that the flow rate of the remaining return oil is equal to or less than the regenerative flow rate, the command opening area of the pressure accumulation control valve 26 is set to regenerate all the flow rate of the remaining return oil by the accumulator 23. Set (step S18). Specifically, by substituting, as P, the differential pressure obtained by subtracting the pressure of the accumulator 23 from the pressure in the head-side oil passage R2 and substituting the remaining return oil flow rate as Q for the equation (1), The command opening area A of the pressure accumulation control valve 26 can be calculated.

  Further, when the command capacity of the regenerative motor 22 is set to the boom reference capacity in step S10, all of the return oil is supplied to the regenerative motor 22 and there is no remaining return oil. Therefore, in step S19, the pressure accumulation control valve is used. 26 command opening area is set to 0 (fully closed).

  When all of the remaining return oil flow rate is supplied to the accumulator 23 in step S18 and when the pressure accumulation control valve 26 is fully closed in step S19, there is no surplus return oil to be recovered in the tank 24. . Therefore, in step S20, the command opening area of the discharge control valve 28 is set to 0 (fully closed).

  If it is determined in step S1 that the lever operation for lowering the boom 6 is not performed, the control valve 19 is switched to the neutral position or the boom raising position, and the boom 6 is held at the current position. Alternatively, it is necessary to switch to a circuit state for allowing the boom 6 to be raised. Therefore, in step S21, the command capacity of the regenerative motor 22 is minimized, the command opening area of the pressure accumulation control valve 26 is set to 0 (fully closed), and the command opening area of the discharge control valve 28 is set to 0 (fully closed). Set to. In step S21, the command opening area of the motor control valve 25 is also set to 0 (fully closed).

  If it is determined in step S1 that the lever operation for lowering the boom 6 is being performed, and if it is determined in step S2 that the regeneration condition is not satisfied, the boom 6 is lowered. However, there is no return oil to be led to the regenerative motor 22 and the accumulator 23. Therefore, in step S22, in order to allow the lowering operation of the boom 6, the command capacity of the regenerative motor 22 is minimized, the command opening area of the pressure accumulation control valve 26 is set to 0 (fully closed), and the discharge control valve 28 command opening area is set to full open. In step S22, the command opening area of the motor control valve 25 is also set to 0 (fully closed).

  Then, after steps S17, S20, S21 and S22, the command values set for the regenerative motor 22 and the control valves 25, 26 and 28 are output (step S23), and the process returns.

  In the hydraulic regenerative device 5 shown in FIG. 2, when the boom 6 is being lowered and the boom 6 performs a load operation (such as when performing an excavation operation), the hydraulic regeneration device 5 is led out to the head side oil passage R <b> 2 of the boom cylinder 9. The return oil is collected in the tank 24 through the discharge control valve 28.

  As described above, in the hydraulic regeneration device 5, the regeneration motor 22 and the accumulator 23 are connected in parallel to the boom cylinder 9, and the control valves 25, 26, and 28 are provided. Therefore, the return oil supplied to the regenerative motor 22 can be relatively reduced by increasing the ratio of the return oil distributed to the accumulator 23 when a large amount of return oil is present.

  Therefore, unlike the prior art in which all of the return oil supplied to the accumulator 23 passes through the regenerative motor 22, the maximum capacity of the regenerative motor 22 can be kept small, thereby suppressing an increase in the size of the regenerative motor 22. In addition, it is possible to reduce the accompanying loss.

  Moreover, according to 1st Embodiment, there can exist the following effects.

  When the accumulator 23 is accumulated by the return oil, not only the energy loss of the accumulator 23 during pressure accumulation but also the energy loss of the regenerative motor 22 driven by the pressure released from the accumulator 23 thereafter occurs. On the other hand, according to the first embodiment, since the return oil is preferentially supplied to the regenerative motor 22 rather than the accumulator 23, energy loss during regeneration by the accumulator 23 is relatively reduced. As a result, a decrease in regeneration efficiency can be suppressed.

  According to the first embodiment, portions of the return oil other than those guided to the regenerative motor 22 and the accumulator 23 can be collected in the tank 24.

  According to the first embodiment, when the drive torque of the regenerative motor 22 exceeds the motor virtual torque (pump torque) of the hydraulic pump 15, the drive efficiency of the engine is reduced by reducing the ratio of the return oil distributed to the regenerative motor. It is possible to regenerate the energy of the return oil while preventing the deterioration of the oil.

  According to the first embodiment, an increase in the speed of the engine 14 can be prevented by using the motor virtual torque of the hydraulic pump 15 and the driving torque of the regenerative motor 22 without detecting the actual speed of the engine 14. .

<Second Embodiment (FIGS. 5 and 6)>
In the first embodiment, when the motor virtual torque (drive torque) of the regenerative motor 22 exceeds the pump torque of the hydraulic pump 15 as in step S11 shown in FIG. 3, the regenerative motor 22 is supplied (distributed). The flow rate of return oil is limited.

  On the other hand, in the second embodiment, the return oil can be regenerated without performing such a restriction on the flow rate of the return oil. Hereinafter, the parts of the second embodiment different from the first embodiment will be mainly described.

  As shown in FIG. 5, the hydraulic regenerative device 5 according to the second embodiment is a generator motor connected to the regenerative motor 22 (the output shaft of the engine 14) so that power can be generated in accordance with the drive of the regenerative motor 22. (Generator) 31, an inverter 32 for controlling the generator motor 31, and a battery 33 capable of charging the power generated by the generator motor 31.

  The generator motor 31 has a function of operating as a generator with the power of at least one of the engine 14 and the regenerative motor 22 and a function of operating as a motor with the power of the battery 33 to assist the power of the engine 14.

  The inverter 32 can control the drive torque (power generation amount) of the generator motor 31 and the power supplied from the battery 33 to the generator motor 31 in accordance with a command from the controller 18. That is, the controller 18 can control the generator motor 31 via the inverter 32.

  Next, processing executed by the controller 18 according to the second embodiment will be described with reference to FIG.

  If it is determined in step S4 described above that the boom lowering target flow rate is larger than the resorbable flow rate of the regenerative motor 22, the relationship with the required torque of the engine 14 (the torque of the hydraulic pump 15) is considered unlike the first embodiment. Without doing so, the command capacity of the regenerative motor 22 is set to the set capacity (step S41). That is, in the state where step S41 is performed, the case where the driving torque of the regenerative motor 22 exceeds the pump torque of the hydraulic pump 15 is included.

  Therefore, in step S51, when the drive torque of the regenerative motor 22 exceeds the pump torque of the hydraulic pump 15, a differential torque obtained by subtracting the pump torque from the drive torque is set as a command torque (power generation torque) of the generator motor 31. When the torque due to driving of the engine 14 has a sufficient margin with respect to the driving torque of the hydraulic pump 15, the command torque of the generator motor 31 can be set to be equal to or greater than the differential torque. On the other hand, if the drive torque is equal to or less than the pump torque in step S51, the command torque of the generator motor 31 is set to zero.

  Next, step S12 described above is executed.

  On the other hand, if it is determined in step S4 that the boom lowering target flow rate is equal to or less than the resorbable flow rate of the regenerative motor 22, the regenerative motor 22 is not considered in consideration of the relationship with the pump torque of the hydraulic pump 15 unlike the first embodiment. Is set to the boom reference capacity (step S71). That is, in the state where step S71 is performed, the case where the drive torque of the regenerative motor 22 exceeds the pump torque of the hydraulic pump 15 is also included.

  Therefore, in step S81, when the driving torque of the regenerative motor 22 exceeds the pump torque of the hydraulic pump 15, a differential torque obtained by subtracting the pump torque from the driving torque is set as a command torque (power generation torque) of the generator motor 31. Similarly to step S51, when the torque due to driving of the engine 14 has a margin relative to the driving torque of the hydraulic pump 15, the command torque of the generator motor 31 can be set to be equal to or greater than the differential torque. On the other hand, if the drive torque is equal to or less than the pump torque in step S81, the command torque of the generator motor 31 is set to zero.

  Next, step S19 described above is executed.

  In the second embodiment, if it is determined in step S2 (see FIG. 3) that the regeneration condition is not satisfied, the command torque of the generator motor 31 is set to 0 in step S22 (see FIG. 4). Set.

  As described above, by maintaining the flow rate of the return oil supplied to the regenerative motor 22 at an absorbable flow rate, it is possible to prevent the drive efficiency of the engine 14 from being lowered while ensuring high regenerative efficiency of the regenerative motor 22. it can.

  Therefore, according to the second embodiment, the energy of the return oil can be regenerated more effectively.

  According to the second embodiment, the increase in the speed of the engine 14 can be prevented by using the pump torque of the hydraulic pump 15 and the driving torque of the regenerative motor 22 without detecting the actual speed of the engine 14. it can.

  In addition, this invention is not limited to embodiment mentioned above. For example, the present invention can take the following aspects.

  The set capacity of the regenerative motor 22 can be appropriately set in consideration of the regeneration efficiency. In general, it is known that a hydraulic motor can obtain a relatively high driving efficiency in a state where the maximum capacity is set. Therefore, if the set capacity of the regenerative motor 22 is set to the maximum capacity as in the above embodiment, energy loss during regeneration by the accumulator 23 is reduced as much as possible while ensuring high driving efficiency of the regenerative motor 22. be able to.

  When the engine 14 is provided with a plurality of loads, the ratio of the return oil distributed to the regenerative motor 22 is reduced so that the drive torque of the regenerative motor 22 is smaller than the total torque generated by driving these loads. As a result, an increase in the speed of the engine 14 can be prevented.

  As the control valves 25 to 28, pilot-type valves may be adopted, and a means for generating a pilot pressure for the control valve in response to a command from the controller 18 may be provided.

  The hydraulic oil discharged from the accumulator 23 can be supplied to another actuator instead of the regenerative motor 22.

  The hydraulic regeneration device 5 is not limited to the one that regenerates the energy of the return oil during the lowering operation of the boom 6, and can regenerate the positional energy or inertial energy of the return oil derived from other hydraulic actuators. . For example, when at least one of the arm 7 and the bucket 8 is rotated by its own weight, the energy of the return oil derived from the cylinders 10 and 11 and the hydraulic motor for driving the upper swing body 3 to rotate are derived at the time of turning deceleration. The energy of the return oil can be regenerated by the hydraulic regenerator 5.

1 Hydraulic excavator (an example of construction machinery)
2 Lower traveling body (an example of the aircraft)
3 Upper revolving structure (an example of the aircraft)
5 Hydraulic regeneration device 6 Boom 9 Boom cylinder (an example of a hydraulic actuator)
DESCRIPTION OF SYMBOLS 14 Engine 15 Hydraulic pump 18 Controller 22 Regenerative motor 23 Accumulator 24 Tank 25 Motor control valve 26 Accumulation control valve 27 Release control valve 31 Generator motor (an example of generator)

Claims (7)

A hydraulic regeneration device,
Engine,
A hydraulic pump driven by the engine;
A hydraulic actuator operated by hydraulic oil from the hydraulic pump;
A variable capacity regenerative motor that can be driven by the supply of return oil derived from the hydraulic actuator, and that is connected to the output shaft of the engine so as to assist the power of the engine by this driving; ,
An accumulator capable of accumulating pressure with return oil from the hydraulic actuator,
The regenerative motor and the accumulator are connected in parallel with each other to the port of the hydraulic actuator from which the return oil is derived,
The hydraulic regeneration device has a distribution adjusting means capable of adjusting a ratio of the return oil distributed to the regeneration motor and the accumulator, and a regeneration condition set in advance as a condition for regenerating the energy of the return oil. A controller that controls the distribution adjusting means so that the return oil is supplied preferentially to the regenerative motor over the accumulator when established ,
When the return oil having a flow rate exceeding the absorbable flow rate that can be absorbed by the regenerative motor adjusted to a preset set capacity is derived from the hydraulic actuator, the controller returns the regenerative oil having the absorbable flow rate to the regenerative flow. It is supplied to the motor, and at least part of the return oil exceeding the absorption flow rate is that control the distribution adjusting means is supplied to the accumulator, the hydraulic recovery device. The hydraulic regeneration device further includes a tank connected in parallel with the regeneration motor and the accumulator with respect to the port of the hydraulic actuator from which the return oil is derived.
The distribution adjusting means is capable of adjusting a ratio of return oil distributed to the regeneration motor, the accumulator, and the tank,
The controller controls the dispensing adjusting means so as to supply the regenerative motor and the return oil other than return oil supplied to the accumulator of the return oil to the tank, the hydraulic recovery device according to claim 1 . When the speed of the engine increases due to the driving of the regenerative motor due to the supply of the return oil, the controller distributes the return oil distributed to the regenerative motor so as to prevent an increase in the speed of the engine The hydraulic regeneration device according to claim 1 or 2 , wherein The controller has a ratio of return oil distributed to the regenerative motor so that the drive torque is less than or equal to the pump torque when the drive torque due to the drive of the regenerative motor exceeds the pump torque due to the drive of the hydraulic pump. The hydraulic regeneration device according to claim 3 , wherein A hydraulic regeneration device,
Engine,
A hydraulic pump driven by the engine;
A hydraulic actuator operated by hydraulic oil from the hydraulic pump;
A variable capacity regenerative motor that can be driven by the supply of return oil derived from the hydraulic actuator, and that is connected to the output shaft of the engine so as to assist the power of the engine by this driving; ,
An accumulator capable of accumulating pressure with return oil from the hydraulic actuator,
The regenerative motor and the accumulator are connected in parallel with each other to the port of the hydraulic actuator from which the return oil is derived,
The hydraulic regeneration device has a distribution adjusting means capable of adjusting a ratio of the return oil distributed to the regeneration motor and the accumulator, and a regeneration condition set in advance as a condition for regenerating the energy of the return oil. When established, the controller that controls the distribution adjusting means so that the return oil is preferentially supplied to the regenerative motor over the accumulator, and power generation is enabled according to the drive of the regenerative motor. further comprising a generator connected to the regeneration motor, and
When the speed of the engine increases due to the driving of the regenerative motor due to the supply of the return oil, the controller generates power with a power generation torque that can prevent an increase in the speed of the engine. You can control the hydraulic regeneration device. When the driving torque generated by driving the regenerative motor exceeds the pump torque generated by driving the hydraulic pump, the controller generates power with the generated torque equal to or greater than the torque obtained by subtracting the pump torque from the driving torque. The hydraulic regeneration device according to claim 5 , wherein the hydraulic generator is controlled. A construction machine,
The aircraft,
A boom attached to the airframe so that it can be raised and lowered;
A hydraulic regeneration device according to any one of claims 1 to 6 ,
The hydraulic actuator provides power for the raising operation and the lowering operation to the boom,
The distribution adjusting means is a construction machine capable of adjusting a ratio of return oil distributed to the regenerative motor and the accumulator during the boom lowering operation.

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