JP2008089023A - Control device of hydraulic actuator and working machine having this control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a hydraulic actuator and a working machine having this control device, capable of reducing the capacity of an accumulator, while effectively utilizing return oil. <P>SOLUTION: In an external force adding period when hydraulic fluid pressure discharged from a hydraulic cylinder 9 exceeds hydraulic fluid pressure supplied to the hydraulic cylinder 9, among a hydraulic fluid discharged from the hydraulic cylinder 9, a hydraulic fluid of a required supply quantity for providing a delivery flow rate required for a hydraulic pump 15, is supplied to a hydraulic motor 20, and a surplus hydraulic fluid except for the supply quantity, is supplied to the accumulator 33. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for a hydraulic actuator having an accumulator for recovering energy of return oil from the hydraulic actuator.

  In general, a working machine such as a hydraulic excavator is provided with a hydraulic actuator such as a hydraulic cylinder or a hydraulic motor.

  This type of hydraulic actuator is configured to be driven by supplying and discharging hydraulic oil. Therefore, when the hydraulic actuator is stopped, it depends on the weight of the object to be driven and the previous driving. The hydraulic actuator continues to drive for a predetermined period due to the inertial force, and the return oil is discharged from the hydraulic actuator during the period.

  Conventionally, such return oil has been collected in a tank via a throttle valve or the like, so the energy of the return oil has been discarded as heat.

  Therefore, as in Patent Document 1, a technique is known in which the energy of return oil is accumulated in an actuator and regenerated.

The pressure oil energy recovery and regeneration device of Patent Document 1 returns to a connection circuit connected to a hydraulic motor, a branch connection circuit branched from the connection circuit and connected to an accumulator, and led to one of these circuits. And a switching valve for switching the oil flow path.
JP 2004-28233 A

  However, since the apparatus of Patent Document 1 is configured to selectively switch between a state in which the hydraulic motor is driven by return oil and a state in which the return oil is accumulated in the accumulator, all of the return oil is supplied to the hydraulic motor. Or it had to be supplied to one of the accumulators.

  Therefore, when supplying all of the return oil to the hydraulic motor, if there is excess hydraulic oil of the return oil, the excess hydraulic oil must be discarded as heat, and the return oil is effectively utilized. I can't.

  On the other hand, when all of the return oil is supplied to the accumulator, a large amount of hydraulic oil is supplied to the accumulator at the time of accumulating pressure, and thus the increase in the size of the accumulator cannot be avoided.

  Therefore, in the apparatus of Patent Document 1, in order to effectively use the return oil, it is impossible to avoid an increase in the size of the accumulator, and there is a possibility that the space of the work machine is wasted.

  The present invention has been made in view of the above problems, and provides a control device for a hydraulic actuator capable of reducing the capacity of an accumulator while effectively utilizing return oil, and a work machine including the control device. It is an object.

  In order to solve the above-mentioned problems, the present invention is a control device for a hydraulic actuator, and is a hydraulic pump that is driven by external power to discharge hydraulic oil, and is supplied with hydraulic oil from the hydraulic pump and operates internally. A hydraulic actuator driven by discharging oil, an accumulator capable of accumulating pressure by supplying hydraulic oil discharged from the hydraulic actuator, and the hydraulic pressure by supplying hydraulic oil discharged from the hydraulic actuator Regenerative means capable of driving the pump, and the operating oil discharged from the hydraulic actuator is in an external force application period exceeding the operating oil pressure supplied to the hydraulic actuator, and the operating oil discharged from the hydraulic actuator is Necessary to drive the regenerative means to obtain the discharge flow rate required for the pump Distributing to supply the required amount of hydraulic oil to the regenerative means and supplying excess hydraulic oil other than the required amount to the accumulator among the hydraulic oil discharged from the hydraulic actuator when the amount exceeds A control device for a hydraulic actuator is provided.

  According to the present invention, when the external oil is applied and the hydraulic oil discharged from the hydraulic actuator exceeds the amount necessary to drive the regenerative means to obtain the discharge flow rate required for the hydraulic pump. Furthermore, among the hydraulic oil discharged from the hydraulic actuator, while supplying the necessary amount to the regenerative means, it is possible to supply only the excess hydraulic oil to the accumulator and accumulate the pressure, so that the hydraulic oil discharged from the hydraulic actuator can be stored. When using all, the amount of hydraulic oil accumulated in the accumulator can be reduced.

  Therefore, according to the present invention, it is possible to reduce the capacity of the accumulator while reducing the power of external power by utilizing the return oil.

  Note that the “external force addition period” refers to the case where the driving direction of the hydraulic actuator matches the direction in which the weight of the driving object is generated, or the driving direction of the hydraulic actuator and the direction in which the inertial force of the driving object is generated. This is a period during which hydraulic fluid having a pressure exceeding the hydraulic pressure supplied to the hydraulic actuator is discharged from the hydraulic actuator, as in the case of matching.

  Specifically, the distribution supply unit is configured to collect the hydraulic fluid discharged from the hydraulic actuator in communication with the recovery flow path capable of guiding the hydraulic oil discharged from the hydraulic actuator to the tank. A regenerative flow path capable of being guided to the regenerative means; a pressure accumulation flow path capable of communicating hydraulic fluid discharged from the hydraulic actuator in communication with the regenerative flow path and the recovery flow path to the accumulator; An on-off valve provided in the recovery channel and capable of opening or closing the recovery channel, a flow rate adjusting unit provided in the regenerative channel and capable of adjusting a flow rate of hydraulic oil flowing in the regenerative channel, and the pressure accumulation A check valve provided in the flow path and the regenerative means are driven to obtain the discharge flow rate required for the hydraulic pump when the hydraulic oil is discharged from the hydraulic actuator during the external force application period. When the amount necessary for the operation is exceeded, the recovery flow path is closed by the on-off valve and the flow rate of the hydraulic oil supplied to the regeneration means by the flow rate adjusting unit so as to be a flow rate according to the required amount And the control valve is configured such that the recovery flow path is closed by the on-off valve and the hydraulic fluid flow rate in the regenerative flow path is adjusted to a predetermined flow rate by the flow rate adjusting unit. When the hydraulic pressure in the pressure accumulation flow path exceeds a preset pressure, the hydraulic oil in the pressure accumulation flow path can be guided to an accumulator.

  In this way, while adjusting the flow rate of the hydraulic oil supplied to the regenerative means by the flow rate adjustment unit, the hydraulic oil pressure in the pressure accumulating flow path is increased by closing the on-off valve to limit the location of the hydraulic oil. Since the check valve can be opened, excess hydraulic oil can be accumulated in the accumulator while supplying the required amount of hydraulic oil to the regenerating means.

  The control means is configured to drive the regenerative means by the driving force of the hydraulic pump for obtaining a required discharge flow rate and the pressure of hydraulic oil discharged from the hydraulic actuator when the on-off valve is closed. It is particularly preferable to control the hydraulic fluid flow rate so that the hydraulic fluid is supplied to the regenerating means and the accumulator when it is determined that the virtual driving force exceeds the driving force of the pump by comparing with the virtual driving force. .

  In this way, when the driving force of the regenerative means that can be driven by the hydraulic oil discharged from the hydraulic actuator exceeds the driving force required for the hydraulic pump, the hydraulic oil is reliably supplied to the regenerative means and the accumulator. Can be supplied.

  The pressure accumulation flow path is provided with a switching valve capable of switching between the check valve and an open flow path capable of supplying hydraulic oil accumulated in the accumulator to the hydraulic actuator through the pressure accumulation flow path. preferable.

  In this way, the hydraulic actuator can be driven using the hydraulic fluid accumulated in the accumulator by switching the switching valve.

  The regenerative unit only needs to have at least a motor function for driving the hydraulic pump. The regenerative unit further has a pump function that is driven by the external power and discharges hydraulic oil into the regenerative flow path. It is particularly preferable to supply hydraulic oil to the hydraulic actuator through the regenerative flow path by exerting a function.

  In this way, the hydraulic fluid discharged from the hydraulic actuator described above can be regenerated by using the motor function, and the discharge flow rate required for the hydraulic pump by using the pump function. A part of can be assisted by regenerative means.

  The present invention is also a work machine having a control device for the hydraulic actuator and a work attachment that is driven by an expansion / contraction operation of a hydraulic cylinder as the hydraulic actuator, wherein the hydraulic cylinder is added with its own weight. The hydraulic oil discharged from the hydraulic cylinder is in an external force application period exceeding the hydraulic pressure supplied to the hydraulic cylinder, and the hydraulic oil discharged from the hydraulic cylinder obtains a discharge flow rate required for the hydraulic pump. When the amount necessary for driving the regenerative means is exceeded, among the hydraulic oil discharged from the hydraulic cylinder, the necessary amount of hydraulic oil is supplied to the regenerative means and surplus other than the necessary amount The working machine is configured to supply the hydraulic oil to the accumulator.

  According to the present invention, when the external oil is applied and the hydraulic oil discharged from the hydraulic cylinder exceeds the amount required to drive the regenerative means to obtain the discharge flow rate required for the hydraulic pump. Furthermore, among the hydraulic oil discharged from the hydraulic cylinder, while supplying the necessary amount to the regenerative means, it is possible to supply only the excess hydraulic oil to the accumulator and accumulate the pressure, so that the hydraulic oil discharged from the hydraulic cylinder can be stored. When using all, the amount of hydraulic oil accumulated in the accumulator can be reduced.

  Specifically, in a work machine having a work attachment, the hydraulic cylinder is always applied with a force in the direction to fall the work attachment (the weight of the work attachment), so during the fall operation period, the hydraulic cylinder The hydraulic pressure discharged from the hydraulic cylinder becomes larger than the hydraulic pressure supplied to the cylinder (external force addition period occurs). In the present invention, the hydraulic oil discharged from the hydraulic cylinder during this period is regenerated. And by supplying to the accumulator, the hydraulic oil can be used effectively.

  Therefore, according to the present invention, it is possible to reduce the size of the accumulator while reducing the external power by utilizing the return oil from the hydraulic cylinder.

  Furthermore, the present invention is a work machine including a control device for the hydraulic actuator and a revolving body that is swiveled by a hydraulic motor as the hydraulic actuator, to which an inertial force of the revolving body is added based on the swivel drive. The hydraulic oil discharged from the hydraulic motor is in an external force application period exceeding the hydraulic pressure supplied to the hydraulic motor, and the hydraulic oil discharged from the hydraulic motor has a discharge flow rate required for the hydraulic pump. When the amount necessary to drive the regenerative means exceeds the required amount, the necessary amount of hydraulic oil discharged from the hydraulic motor is supplied to the regenerative means and the necessary Provided is a work machine configured to supply surplus hydraulic oil other than an amount to the accumulator.

  According to the present invention, when the external oil is applied and the hydraulic oil discharged from the hydraulic motor exceeds the amount necessary to drive the regenerative means to obtain the discharge flow rate required for the hydraulic pump. Further, among the hydraulic oil discharged from the hydraulic motor, while supplying the necessary amount to the regenerative means, only the excess hydraulic oil can be supplied to the accumulator to accumulate pressure, so that the hydraulic oil discharged from the hydraulic motor can be stored. When using all, the amount of hydraulic oil accumulated in the accumulator can be reduced.

  Specifically, in a work machine having a swing body, the inertial force of the swing body in the swing drive direction is always applied to the hydraulic motor. Therefore, the hydraulic pressure supplied to the hydraulic motor during the swing operation period However, in the present invention, the operating oil discharged from the hydraulic motor is supplied to the regeneration means and the accumulator during this period. Thus, the hydraulic oil can be effectively used.

  Therefore, according to the present invention, it is possible to reduce the size of the accumulator while reducing the external power by utilizing the return oil from the hydraulic motor.

  According to the present invention, it is possible to reduce the capacity of the accumulator while effectively using the return oil.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing a hydraulic excavator according to an embodiment of the present invention.

  Referring to FIG. 1, a hydraulic excavator 1 as an example of a working machine includes a lower traveling body 2 having a crawler 2a, an upper revolving body 3 that is turnably mounted on the lower traveling body 2, and an upper portion thereof. The work attachment 4 supported by the revolving structure 3 so as to be raised and lowered, and a control device (see FIG. 2) 5 for controlling the drive of the work attachment 4 are provided.

  The work attachment 4 includes a boom 6 and an arm 7 connected to the distal end portion of the boom 6, and a bucket 8 is swingably attached to the distal end portion of the arm 7.

  The boom 6 is raised and lowered by the expansion and contraction operation of the boom cylinder 9, the arm 7 is swung by the expansion and contraction operation of the arm cylinder 10, and the bucket 8 is swung with respect to the arm 7 by the expansion and contraction operation of the bucket cylinder 11. That is, in this embodiment, each cylinder 9-11 comprises an example of a hydraulic actuator.

  FIG. 2 is a circuit diagram showing an electrical and hydraulic configuration of a control device provided in the excavator of FIG. FIG. 3 is a diagram mainly showing a hydraulic circuit of the control device of FIG.

  2 and 3, the control device 5 includes a hydraulic circuit 12 including the cylinders 9 to 11, and a controller (control means) 14 that electrically controls the flow of hydraulic oil in the hydraulic circuit 12. I have. 2 and 3, the bucket cylinder 11 is omitted.

  The hydraulic circuit 12 supplies hydraulic oil discharged from the main pump 15 to the boom cylinder 9 and the arm cylinder 10 through a pair of switching valves 16 and 17, respectively, while returning from the cylinders 9 and 10. The oil is recovered in the tank 18 through the switching valves 16 and 17.

  The main pump 15 is mechanically connected to an output shaft of an engine (external power) 19 and discharges hydraulic oil in accordance with the driving of the engine 19.

  The main pump 15 is also mechanically coupled to the output shaft of the hydraulic motor 20 and can discharge hydraulic oil in accordance with the driving of the hydraulic motor 20. On the contrary, the hydraulic motor 20 can discharge hydraulic oil in accordance with the driving of the main pump 15.

  The hydraulic oil discharged from the main pump 15 is guided to the switching valves 16 and 17 through the branch flow path 21 and the branch flow path 22, respectively.

  The switching valves 16 and 17 are three-position switching valves, and are switched according to the operation of the operation lever 23 and the operation lever 24. Each operation lever 23, 24 has a remote control valve 23a and a remote control valve 24a for supplying pilot pressure corresponding to the operation amount to the pilot port of each switching valve 16, 17 via the pilot circuit 25 and pilot circuit 26, respectively. Yes.

  In a state where these operation levers 23 and 24 are not operated, the switching valves 16 and 17 are respectively held in the neutral position (switching position in FIG. 2), and the branch flow paths 21 and 22 are closed in this neutral position. .

  When the operation levers 23 and 24 are operated to the right side in the figure and the switching valves 16 and 17 are operated to the switching position on the left side in the figure, the branch flow paths 21 and 22 are connected to the head side ports of the hydraulic cylinders 9 and 10. The head-side flow path 27 and the head-side flow path 28 are connected to each other.

  At this time, the rod side flow path 29 and the rod side flow path 30 connected to the rod side ports of the hydraulic cylinders 9 and 10 are respectively connected to the recovery flow path 31 and the recovery flow path 32 connected to the tank 18. The

  On the other hand, when the operation levers 23 and 24 are operated to the left side in the figure and the switching valves 16 and 17 are operated to the switching position on the right side in the figure, the branch flow paths 21 and 22 are connected to the rod side flow paths 29 and 30, respectively. At the same time, the head-side channels 27 and 28 are connected to the recovery channels 31 and 32, respectively.

  The hydraulic circuit 12 according to the present embodiment includes an accumulator 33, a pressure accumulation channel 34 branched from the head side channel 27 and connected to the accumulator 33, and a two-position switching valve provided in the pressure accumulation channel 34. (Switching valve) 35, a first throttle valve (open / close valve) 36 provided in the recovery flow path 31 and capable of adjusting the flow rate of hydraulic fluid flowing through the recovery flow path 31, and the head side flow path 27. A regenerative flow path 37 connected to the hydraulic motor 20 and a second throttle valve (flow rate adjusting unit) 38 provided in the regenerative flow path 37 and capable of adjusting the flow rate of hydraulic fluid flowing through the regenerative flow path 37. And further.

  The recovery flow path 31, the regenerative flow path 37, the pressure accumulation flow path 34, the 2-position switching valve 35, the first throttle valve 36, the second throttle valve 38, and the controller 14 to be described later are the distribution supply means in the present embodiment. Configure an example.

  The two-position switching valve 35 is held at the switching position shown in FIGS. In this switching position, the two-position switching valve 35 functions as a check valve that allows the hydraulic oil to flow to the accumulator 33 side when the pressure of the hydraulic oil in the pressure accumulation passage 34 exceeds a preset pressure. . Therefore, it is possible to accumulate pressure in the accumulator 33 at this switching position.

  On the other hand, when the signal from the controller 14 is received, the two-position switching valve 35 is switched to the switching position shown in FIG. When operated to this switching position, the accumulator 33 can supply the accumulated energy to the head side flow path 27 side.

  The first throttle valve 36 is a throttle valve that is opened in a state where it does not receive an electrical signal from the controller 14 to be described later, and by adjusting the opening degree according to the strength of the electrical signal from the controller 14. It is possible to adjust the flow rate of the hydraulic oil flowing through the recovery passageway 31.

  The second throttle valve 38 is a throttle valve that is closed in a state where it does not receive an electrical signal from the controller 14 described later, and by adjusting the opening degree according to the strength of the electrical signal from the controller 14. The flow rate of hydraulic oil flowing through the regenerative flow path 37 can be adjusted.

  The controller 14 not only outputs electrical signals to the two-position switching valve 35, the first throttle valve 36, and the second throttle valve 38, but also acquires information on the hydraulic circuit 12 by receiving inputs from various sensors. It is supposed to be.

  Specifically, the controller 14 receives the output signals from the pressure sensor 39 and the pressure sensor 40 provided in the pilot circuit 25, and receives the pilot pressure P1 and the pilot pressure applied to each of the pilot ports of the switching valve 16. P2 (see FIG. 3) is detected.

  Further, the controller 14 receives an output signal from the pressure sensor 41 and detects the discharge pressure P3 (see FIG. 3) of the hydraulic oil from the main pump 15.

  Further, the controller 14 receives an output signal from the pressure sensor 42 provided in the head side flow path 27, and detects the pressure P4 (see FIG. 3) of the hydraulic oil flowing through the head side flow path 27. It has become.

  The controller 14 receives an output signal from a rotational speed sensor 43 provided in the engine 19 and detects the engine rotational speed ω (see FIG. 3).

  Based on the information from the hydraulic circuit 12, the controller 14 supplies the return oil from the hydraulic cylinder 9 to the hydraulic motor 20 and the accumulator 33 so that the return oil is effectively utilized. The following processing is executed.

  FIG. 5 is a flowchart showing processing executed by the controller of FIG.

  2 to 4 and FIG. 5, when the processing of the controller 14 is executed, first, pilot pressures P1 and P2 are detected by the pressure sensors 39 and 40 (step S1).

  Next, it is determined whether or not the pilot pressure P1 is increasing among these pilot pressures P1 and P2 (step S2). That is, in this step S2, it is determined whether or not the pilot pressure P1 has increased and the switching valve 16 has been operated to the switching position on the right side shown in FIG.

  Here, if it is determined that the pilot pressure P1 has not increased (NO in step S2), step S1 is executed, while if it is determined that the pilot pressure P1 has increased (YES in step S2). Then, the first throttle valve 36 is closed (step S3).

  That is, when the switching valve 16 is operated to the switching position on the right side, the head side flow path 27 is connected to the recovery flow path 31 and the rod side flow path 29 is changed to the branch flow path 21 as shown in FIG. As a result, the hydraulic cylinder 9 is contracted, that is, the boom 6 (see FIG. 1) is lying down.

  During this overturning operation, the direction in which the weight of the boom 6 is generated is added to the rod reduction direction of the hydraulic cylinder 9, so that the hydraulic oil supplied to the hydraulic cylinder 9 is discharged from the hydraulic cylinder 9. The working oil pressure becomes larger (external force application period occurs).

  Then, in order to effectively utilize the return oil from the hydraulic cylinder 9 during this external force addition period, the return oil is prevented from being guided to the tank 18 by closing the first throttle valve 36 in step S3.

  Next, the required power W1 for driving the main pump 15 at the currently requested discharge flow rate is calculated by the following equation (1) (step S4).

W1 = P3 × Q1 × ω (1)
Here, Q1 is the motor capacity of the main pump 15 and is stored in the controller 14 in advance. P3 is the pressure of the main pump 15, and ω is the rotational speed of the engine 19.

  Subsequently, the virtual regenerative power W2 of the hydraulic motor 20 when the hydraulic motor 20 is driven by the return oil from the hydraulic cylinder 9 is calculated by the following equation (2) (step S5).

W2 = P4 × Q2 × ω (2)
Here, Q2 is the motor capacity of the hydraulic motor 20, and is stored in the controller 14 in advance. P4 is the hydraulic pressure in the head side flow path 27, and ω is the rotational speed of the engine 19.

  Next, it is determined whether or not the virtual regenerative power W2 calculated in this way is larger than the power W1 (step S6).

  That is, in this step S6, the return oil from the hydraulic cylinder 9 includes surplus hydraulic oil that exceeds the amount necessary to generate the power W1 for driving the main pump 15 at the required discharge flow rate. It is determined whether or not.

  If it is determined that excess hydraulic oil is included in the return oil (YES in step S6), the opening of the second throttle valve 38 is calculated by the following equation (3) (step S7).

Q3 = W1 / (P4 × ω) (3)
That is, the flow rate Q3 required to be supplied to the hydraulic motor 20 in order to drive the main pump 15 at the requested discharge flow rate is calculated by this equation (3). In step S7, the flow rate Q3 corresponding to the flow rate Q3 is calculated. The opening degree of the 2 throttle valve 38 is specified.

  Next, the second throttle valve 38 is opened at the opening specified in step S7, and the drive of the engine 19 is stopped (step S8). Thereby, since the main pump 15 can be driven only by the return oil from the hydraulic cylinder 9, energy saving can be achieved by stopping the driving of the engine 19.

  Further, by reducing the opening of the second throttle valve 38, the pressure in the regenerative flow path 37 and the pressure accumulating flow path 34 communicating therewith increases, and when this pressure becomes equal to or higher than a preset pressure. Then, the check valve of the two-position switching valve 35 is opened, and the accumulator 33 is accumulated. Therefore, surplus hydraulic oil for driving the hydraulic motor 20 can be used for accumulating the accumulator 33.

  Next, it is determined whether or not the discharge pressure P3 of the main pump 15 is decreased (step S9). That is, in step S9, it is determined whether or not the pressure of the main pump 15 is decreasing. If it is determined that the pressure is not decreasing (NO in step S9), step S4 is repeatedly executed.

  On the other hand, if it is determined that the pressure of the main pump 15 is decreasing (YES in step S9), and if it is determined in step S6 that the virtual regenerative power W2 is not greater than the necessary power W1 (in step S6). NO), the first throttle valve 36 is returned to the open state, the second throttle valve 38 is returned to the closed state, and the engine 19 is restarted (step S10), and the process returns to step S1. .

  The energy stored in the accumulator 33 as described above can be utilized when the rod of the hydraulic cylinder 9 is extended by operating the switching valve 17 to the left switching position, as shown in FIG.

  That is, when the hydraulic oil is supplied from the main pump 15 to the head-side flow path 27, the hydraulic oil stored in the accumulator 33 is moved into the rod-side chamber of the hydraulic cylinder 9 by operating the two-position switching valve 35. Can be supplied.

  Therefore, since the hydraulic oil from the accumulator 33 can be supplied to the hydraulic cylinder 9 in addition to the hydraulic oil from the main pump 15, the boom 6 can be quickly raised.

  In addition, the hydraulic motor 20 can be used as a hydraulic pump in a state where the switching valve 17 is operated to the left switching position.

  That is, in the state shown in FIG. 4, if the power of the engine 19 is also supplied to the hydraulic motor 20, the hydraulic oil discharged from the hydraulic motor 20 passes through the regenerative flow path 37 and is on the rod side of the hydraulic cylinder 9. It will be supplied indoors. At this time, the second throttle valve 38 needs to be opened.

  As described above, according to the control device 5, the hydraulic motor 20 is driven to obtain the discharge flow rate required for the main pump 15 by the hydraulic oil discharged from the hydraulic cylinder 9 during the external force application period. The excess hydraulic oil is supplied to the hydraulic motor 20 while supplying the hydraulic oil 20 with an amount necessary for securing the discharge amount of the main pump 15 among the hydraulic oil discharged from the hydraulic cylinder 9 when the amount necessary for the operation is exceeded. Therefore, when all the hydraulic fluid discharged from the hydraulic cylinder 9 is used, the amount of hydraulic fluid accumulated in the accumulator 33 can be reduced.

  Therefore, according to the control device 5, the capacity of the accumulator 33 can be reduced while using the return oil to reduce the power of the engine 19.

  Specifically, in the control device 5, the flow of hydraulic oil is limited by closing the first throttle valve 36 while adjusting the flow rate of hydraulic oil supplied to the hydraulic motor 20 by the second throttle valve 38. Since the hydraulic pressure in the pressure accumulating flow path 34 can be increased to open the check valve of the two-position switching valve 35, the surplus hydraulic oil is supplied to the accumulator while supplying the hydraulic oil 20 with a necessary flow rate. 33 can be accumulated.

  Then, as in step S6, the controller 14 discharges from the hydraulic cylinder 9 when the required power W1 of the main pump 15 for obtaining the required discharge flow rate and the first throttle valve 36 are closed during the period of external force application. Compared with the virtual regenerative power W2 when the hydraulic motor 20 is driven by the pressure of the hydraulic oil to be applied, and when it is determined that the virtual regenerative power W2 exceeds the necessary power W1 as in step S7, the hydraulic motor If the hydraulic oil flow rate is controlled so that the hydraulic oil is supplied to the hydraulic actuator 20 and the accumulator 33, when there is an excess return oil, the hydraulic oil is surely supplied to the hydraulic motor 20 and the accumulator 33. Can do.

  If the two-position switching valve 35 is provided as in the control device 5, the hydraulic cylinder 9 is driven by using the hydraulic oil accumulated in the accumulator 33 by switching the switching valve 16. be able to.

  As in the control device 5, a hydraulic motor having a motor function for driving the main pump 15 upon receiving hydraulic oil supply and a pump function for discharging the hydraulic oil into the regenerative flow path 37 in accordance with the driving of the engine 19. 20 is used, the hydraulic fluid discharged from the hydraulic cylinder 9 can be regenerated by using the motor function, and the discharge flow rate required for the main pump 15 by using the pump function. Can be assisted by the hydraulic motor 20.

  Then, according to the hydraulic excavator 1 that is used to control the drive of the hydraulic cylinder 9 that drives the work attachment 4, the hydraulic fluid discharged from the hydraulic cylinder 9 during an external force application period is used. Of the hydraulic oil discharged from the hydraulic cylinder 9 when the amount exceeds the amount necessary to drive the hydraulic motor 20 to obtain the discharge flow rate required for the hydraulic pump 15. In the case of using all of the hydraulic oil discharged from the hydraulic cylinder 9, only the surplus hydraulic oil can be supplied to the accumulator 33 to accumulate pressure while supplying the hydraulic motor 20 with an amount necessary for securing the hydraulic pressure. The amount of hydraulic oil accumulated in the accumulator 33 can be reduced.

  Specifically, in the hydraulic excavator 1 having the work attachment 4, the hydraulic cylinder 9 is always applied with a force in the direction in which the work attachment 4 is laid down (the weight of the work attachment 4). In this case, the hydraulic pressure discharged from the hydraulic cylinder 9 becomes larger than the hydraulic pressure supplied to the hydraulic cylinder 9 (an external force addition period occurs). In the hydraulic excavator 1, the hydraulic cylinder during this period By supplying the hydraulic oil discharged from 9 to the hydraulic motor 20 and the accumulator 33, the hydraulic oil can be used effectively.

  Therefore, according to the hydraulic excavator 1, it is possible to reduce the size of the accumulator 33 while reducing the power of the engine 19 by utilizing the return oil from the hydraulic cylinder 9.

  In the above embodiment, the control device 5 that controls the drive of the hydraulic cylinders 9 to 11 for driving the work attachment 4 has been described. However, as shown in FIGS. 6 and 7, the upper swing body 3 (see FIG. 1). As described above, the return oil can also be effectively used for the control device 45 that controls the drive of the drive turning motor 44.

  FIG. 6 is a circuit diagram showing a control device according to another embodiment of the present invention. FIG. 7 is a circuit diagram mainly showing the hydraulic circuit of FIG. In addition, about the structure similar to embodiment mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  Referring to FIGS. 6 and 7, the control device 45 includes a hydraulic circuit 46 including a turning motor 44 and a controller (control means) 47 that electrically controls the flow of hydraulic oil in the hydraulic circuit 46. .

  The hydraulic circuit 46 supplies the hydraulic oil discharged from the main pump 15 to the turning motor 44 through the switching valve 16, while collecting the return oil discharged from the turning motor 44 into the tank 18 through the switching valve 16. ing.

  Specifically, the first flow path 48 is connected to one port of the swing motor 44, while the second flow path 49 is connected to the other port of the swing motor 44. Depending on the switching operation of the switching valve 16, it is connected to the branch flow path 21 or the recovery flow path 31, respectively.

  The first flow path 48 is provided with a first regenerative flow path 50 that is branched from the middle of the first flow path 48 and connected to the hydraulic motor 20. The first regenerative flow path 50 includes the second throttle valve 38. Is provided.

  Furthermore, a two-position switching valve 51 is provided in the first regenerative flow path 50 at a position closer to the first regenerative flow path 50 than the second throttle valve 38. The two-position switching valve 51 receives a signal from the switching position for closing the first regenerative flow channel 50 and a signal from the controller 47 in a state where an electrical signal from the controller 47 described later is not received. Switching between a switching position where the path 50 is opened is possible.

  On the other hand, the second flow path 49 is provided with a second regenerative flow path 52 that is branched from the middle thereof and connected to the first regenerative flow path 50. The second regeneration channel 52 is connected to the first regeneration channel 50 at a position between the second throttle valve 38 and the two-position switching valve 51.

  The second regenerative flow path 52 is provided with a two-position switching valve 53. The two-position switching valve 53 receives a signal from the controller 47 and a switching position for closing the second regenerative flow path 52 in a state where an electrical signal from the controller 47 described later is not received. It is possible to switch between a switching position where 52 is opened.

  Further, the second regenerative flow channel 52 is provided with a pressure accumulation flow channel 54 that is branched from the middle thereof and connected to the accumulator 33. The pressure accumulation channel 54 branches from the second regeneration channel 52 at a position closer to the first regeneration channel 50 than the two-position switching valve 53.

  The second regenerative flow path 52 is provided with a two-position switching valve 35 similar to that in the above embodiment.

  The recovery flow path 31, the regenerative flow paths 50 and 52, the pressure accumulation flow path 54, the throttle valves 36 and 38, the 2-position switching valve 35, the 2-position switching valves 51 and 53, and a controller 47 described later. This constitutes an example of the distribution supply means of the present invention.

  The controller 47 detects the pressures P1 to P3 by the pressure sensors 39 to 41 as in the above embodiment, and the pressure sensor 55 provided in the first channel 48 causes the hydraulic oil in the first channel 48 to flow. The pressure P5 is detected.

  Then, the controller 47 supplies the return oil from the turning motor 44 to the hydraulic motor 20 and the accumulator 33 based on such information of the hydraulic circuit 46 so that the return oil can be effectively used. The process like this is executed.

  FIG. 8 is a flowchart showing the first half of the process executed by the controller shown in FIG. FIG. 9 is a flowchart showing the latter half of the process executed by the controller shown in FIG.

  6 to 8, when the process of controller 47 is executed, first, pilot pressures P1 and P2 are detected by pressure sensors 39 and 40 (step T1).

  Next, by specifying which of the pilot pressures P1 and P2 is high, the operation position of the switching valve 16, that is, the rotational direction of the swing motor 44 is specified, and the first flow path 48, Among the two flow paths 49, the flow path through which the hydraulic oil discharged from the turning motor 44 flows is identified (step T2).

  Here, the flow path on the return side is specified because, in a state where the turning motor 44 is rotationally driven, the inertial force according to the weight of the upper turning body 3 (see FIG. 1) that is turning is turned. By generating in the direction, the hydraulic pressure discharged from the swing motor 44 is larger than the hydraulic pressure supplied to the swing motor 44 (an external force addition period occurs). This is to make effective use of oil.

  In the following description, as shown in FIG. 7, a case where the switching valve 16 is operated to the switching position on the right side and the first flow path 48 is specified as a return-side flow path will be exemplified.

  When the first flow path 48 is specified as the return flow path (step T2), the two-position switching valve 51 provided in the first regeneration flow path 50 is opened (step T3), and the first throttle valve 36 is opened. Is closed (step T4).

  Next, the required power W1 is calculated from the equation (1) (step T5), and the virtual regenerative power W2 is calculated from the equation (2) (step T6).

  Referring to FIG. 9, next, it is determined whether or not the virtual regenerative power W2 exceeds the necessary power W1 (step T7). If it is determined that the virtual regenerative power W2 exceeds the required power W1 (YES in step T7), (3 ) To calculate the opening of the second throttle valve 38 (step T8).

  Next, the second throttle valve 38 is opened at the opening specified in step T8, and the drive of the engine 19 is stopped (step T9). Thereby, since the main pump 15 can be driven only by the return oil from the turning motor 44, energy saving by stopping the driving of the engine 19 can be achieved.

  Furthermore, the pressure in the 1st regeneration flow path 50 and the 2nd regeneration flow path 52 will increase by restrict | squeezing the opening degree of the said 2nd throttle valve 38. FIG. When this pressure is equal to or higher than a preset pressure, the check valve of the two-position switching valve 35 is opened and pressure accumulation in the accumulator 33 is performed. Therefore, surplus hydraulic oil for driving the turning motor 44 can be used for accumulating the accumulator 33.

  Next, it is determined whether or not the discharge pressure P3 of the main pump 15 is decreased (step T10). That is, in step T10, it is determined whether or not the pressure of the main pump 15 is decreasing. If it is determined that the pressure is not decreasing (NO in step T10), the process returns to step T5.

  On the other hand, if it is determined that the pressure of the main pump 15 is decreasing (YES in step T10), and if it is determined in step T7 that the virtual regenerative power W2 is not greater than the necessary power W1 (in step T7). NO) closes the two-position switching valve 51 (step T11).

  Next, the first throttle valve 36 is returned to the open state, the second throttle valve 38 is returned to the closed state, and the engine 19 is restarted (step T12), and the process returns to step T1.

  The energy stored in the accumulator 33 as described above is used to open the two-position switching valve 35 and open the two-position switching valve when the switching valve 16 is operated to the right switching position as shown in FIG. By opening 53, the second flow path 49 is supplied.

  On the other hand, in a state in which the switching valve 16 is operated to the left switching position, the energy stored in the accumulator 33 is stored in the first position by opening the two-position switching valve 35 and opening the two-position switching valve 51. The flow path 48 can be supplied.

  As described above, according to the control device 45, the hydraulic oil discharged from the swing motor 44 drives the regenerative means in order to obtain the discharge flow rate required for the main pump 15 during the external force application period. Of the hydraulic oil discharged from the slewing motor 44 when the amount required for the main pump 15 is exceeded. Can be supplied to the accumulator 33 to accumulate pressure, so that when using all of the hydraulic oil discharged from the turning motor 44, the amount of hydraulic oil to be accumulated in the accumulator 33 can be reduced.

  Specifically, in the hydraulic excavator 1 having the upper swing body 3, since the inertia force of the upper swing body 3 in the swing drive direction is always applied to the swing motor 44, the swing motor 44 rotates during the swing operation period. The hydraulic pressure discharged from the swing motor 44 is larger than the hydraulic pressure supplied to the motor 44 (an external force addition period occurs). In the above embodiment, the hydraulic pressure is discharged from the swing motor 44 during this period. By supplying the hydraulic oil to the hydraulic motor 20 and the accumulator 33, the hydraulic oil can be effectively used.

  Therefore, according to the embodiment, the accumulator 33 can be reduced in size while reducing the power of the engine 19 by utilizing the return oil from the turning motor 44.

1 is a side view showing a hydraulic excavator according to an embodiment of the present invention. It is a circuit diagram which shows the electrical and hydraulic structure of the control apparatus provided in the hydraulic shovel of FIG. It is a figure which mainly shows the hydraulic circuit of the control apparatus of FIG. It is a figure which mainly shows the hydraulic circuit of the control apparatus of FIG. It is a flowchart which shows the process which the controller of FIG. 2 performs. It is a circuit diagram which shows the control apparatus which concerns on another embodiment of this invention. FIG. 7 is a circuit diagram mainly showing the hydraulic circuit of FIG. 6. It is a flowchart which shows the first half part of the process performed by the controller shown in FIG. It is a flowchart which shows the second half part of the process performed by the controller shown in FIG.

Explanation of symbols

W1 Required power W2 Virtual regenerative power 1 Hydraulic excavator (work machine)
3 Upper swing body (revolving body)
4 Work attachment 5 Control device 9 Boom cylinder (hydraulic cylinder)
DESCRIPTION OF SYMBOLS 10 Arm cylinder 11 Bucket cylinder 12 Hydraulic circuit 14 Controller (control means)
15 Main pump (hydraulic pump)
19 Engine (external power)
20 Hydraulic motor (regenerative means)
31 Recovery Channel 33 Accumulator 34 Accumulation Channel 35 2 Position Switching Valve 36 First Throttle Valve (Open / Close Valve)
37 Regenerative flow path 38 Second throttle valve (flow rate adjustment part)
44 Rotating motor (hydraulic motor)
45 controller 47 controller (control means)
50 First regeneration channel 52 Second regeneration channel 54 Accumulation channel

Claims (7)

A control device for a hydraulic actuator,
A hydraulic pump that is driven by external power and discharges hydraulic oil;
A hydraulic actuator that is driven by supplying hydraulic oil from the hydraulic pump and discharging the internal hydraulic oil;
An accumulator capable of accumulating pressure by supplying hydraulic oil discharged from the hydraulic actuator;
Regenerative means capable of driving the hydraulic pump by supplying hydraulic oil discharged from the hydraulic actuator;
The hydraulic oil discharged from the hydraulic actuator is in an external force application period exceeding the hydraulic pressure supplied to the hydraulic actuator, and the hydraulic oil discharged from the hydraulic actuator obtains a discharge flow rate required for the hydraulic pump. Therefore, when the amount necessary to drive the regenerative means exceeds the required amount, among the hydraulic oil discharged from the hydraulic actuator, the necessary amount of hydraulic oil is supplied to the regenerative means and other than the necessary amount A hydraulic actuator control device comprising: distribution supply means for supplying excess hydraulic oil to the accumulator.   The distribution supply means includes a recovery passage capable of guiding the hydraulic oil discharged from the hydraulic actuator to the tank, and the hydraulic oil discharged from the hydraulic actuator in communication with the recovery passage to the regeneration means. A regenerative flow path that can be guided, a pressure accumulation flow path that communicates with the regenerative flow path and the recovery flow path and that can guide hydraulic oil discharged from the hydraulic actuator to the accumulator, and the recovery flow path Provided in the regenerative flow path, a flow rate adjusting unit capable of adjusting the flow rate of hydraulic oil flowing in the regenerative flow path, and the pressure accumulating flow path. The check valve and the hydraulic oil discharged from the hydraulic actuator during the external force application period drive the regeneration means to obtain a discharge flow rate required for the hydraulic pump. When the required amount is exceeded, the recovery flow path is closed by the on-off valve, and the flow rate of the hydraulic oil supplied to the regenerative means is controlled by the flow rate adjusting unit so that the flow rate according to the required amount is obtained. And the check valve closes the recovery flow path by the on-off valve and adjusts the flow rate of hydraulic oil in the regenerative flow path to a predetermined flow rate by the flow rate adjusting unit. The hydraulic actuator control device according to claim 1, wherein the hydraulic oil in the pressure accumulating flow path is guided to an accumulator when the hydraulic pressure in the cylinder exceeds a preset pressure.   The control means is configured to drive the regenerative means by the driving force of the hydraulic pump for obtaining a required discharge flow rate and the pressure of hydraulic oil discharged from the hydraulic actuator when the on-off valve is closed. Comparing with the virtual driving force, when it is determined that the virtual driving force exceeds the driving force of the pump, the hydraulic oil flow rate is controlled so that the hydraulic oil is supplied to the regeneration means and the accumulator. The control device for a hydraulic actuator according to claim 2.   The pressure accumulation flow path is provided with a switching valve capable of switching between the check valve and an open flow path capable of supplying hydraulic oil accumulated in the accumulator to the hydraulic actuator through the pressure accumulation flow path. The control device for a hydraulic actuator according to claim 2, wherein the control device is a hydraulic actuator.   The regenerative means is mechanically connected to the hydraulic pump and receives a supply of hydraulic oil to drive the hydraulic pump, and is driven by the external power to discharge the hydraulic oil into the regeneration flow path. The hydraulic actuator according to any one of claims 2 to 4, wherein the hydraulic actuator is supplied to the hydraulic actuator through the regenerative flow path by exhibiting the pump function. Control device.   A working machine comprising: the hydraulic actuator control device according to any one of claims 1 to 5; and a work attachment driven by an expansion and contraction operation of a hydraulic cylinder as the hydraulic actuator, wherein the weight of the work attachment is reduced. The hydraulic oil that is added and discharged from the hydraulic cylinder is in an external force application period that exceeds the hydraulic pressure supplied to the hydraulic cylinder, and the hydraulic oil discharged from the hydraulic cylinder is requested to be discharged from the hydraulic pump. When the amount necessary to drive the regenerative unit is exceeded in order to obtain a flow rate, among the hydraulic oil discharged from the hydraulic cylinder, the necessary amount of hydraulic oil is supplied to the regenerative unit, A working machine configured to supply surplus hydraulic oil other than the necessary amount to the accumulator.   A working machine comprising: the hydraulic actuator control device according to any one of claims 1 to 5; and a revolving body that is revolvingly driven by a hydraulic motor as the hydraulic actuator, wherein the revolving body is based on a revolving drive. The hydraulic oil discharged from the hydraulic motor with the inertial force is applied during an external force application period exceeding the hydraulic pressure supplied to the hydraulic motor, and the hydraulic oil discharged from the hydraulic motor is supplied to the hydraulic pump. When the amount necessary for driving the regenerative unit is exceeded in order to obtain the required discharge flow rate, the required amount of hydraulic oil discharged from the hydraulic motor is supplied to the regenerative unit. A work machine configured to supply excess hydraulic oil other than the required amount to the accumulator.

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