JP2014074433A - Hydraulic circuit for construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic circuit for a construction machine, capable of calculating a pressure difference between the upstream side and the downstream side of a regeneration valve arranged in an oil path which resupplies return oil to hydraulic actuators, and of controlling the opening of the regeneration valve on the basis of the calculated pressure difference.SOLUTION: The hydraulic circuit for the construction machine for controlling the operation of the plurality of hydraulic actuators includes detection means 23 for detecting first driving pressure of pressure oil supplied to one hydraulic actuator and second driving pressure of pressure oil supplied to the other hydraulic actuator, a regenerative circuit 24 for resupplying return oil from one hydraulic actuator, and control means 30 for controlling a hydraulic pump, the detection means and the regenerative circuit. The regenerative circuit includes a regeneration valve 24Vth provided in the oil path which resupplies the return oil, and the control means includes a pressure difference calculation part for calculating a pressure difference between hydraulic oil pressure on the upstream side of the regeneration valve and hydraulic oil pressure on the downstream side thereof on the basis of a load pressure difference between the first driving pressure and the second driving pressure. It controls the opening of the regeneration valve on the basis of the calculated pressure difference.

Description

  The present invention relates to a hydraulic circuit of a construction machine.

  Some construction machines include a regeneration circuit that re-feeds return oil from a hydraulic cylinder (hydraulic actuator) to the hydraulic cylinder in order to ensure operability independent of load fluctuations (for example, Patent Document 1). In addition, for example, when the arm closing operation and the boom raising operation are performed at the same time (during compound operation), the construction machine has an arm according to the boom raising operation amount in order to ensure the operability of the arm on the low load side. Some return oil is re-supplied to the drive side of the cylinder (for example, Patent Document 2).

JP 2004-76904 A JP 2007-23606 A

  In the technique disclosed in Patent Document 1, in order to re-supply oil to one hydraulic actuator, the opening degree of the regeneration valve of the regeneration circuit is changed according to the load pressure of the one hydraulic actuator. For this reason, in the technique disclosed in Patent Document 1, there is a case where the operation speed of the hydraulic actuator cannot be ensured at the time of a composite operation in which two or more hydraulic actuators are operated.

  Moreover, in the technique disclosed in Patent Document 2, a throttle is provided on the inlet side of a directional control valve (for example, an arm control valve) disposed on the most downstream side of the oil passage in order to ensure composite operability. . For this reason, in the technique disclosed in Patent Document 2, the pressure loss of the pressure oil discharged from the hydraulic pump during the combined operation may increase.

  The present invention has been made under such circumstances, and is a hydraulic circuit of a construction machine that controls the operation of a plurality of hydraulic actuators, and is disposed in an oil passage that re-feeds return oil to a hydraulic actuator (hydraulic cylinder). Another object of the present invention is to provide a hydraulic circuit for a construction machine that can calculate the differential pressure between the upstream side and the downstream side of the regeneration valve and control the opening degree of the regeneration valve based on the calculated differential pressure.

  According to one aspect of the present invention, there is provided a hydraulic circuit for a construction machine that controls operation of a plurality of hydraulic actuators using pressure oil discharged from a hydraulic pump, wherein one of the plurality of hydraulic actuators is controlled. Detecting means for detecting a first driving pressure of the pressure oil supplied to the hydraulic actuator and a second driving pressure of the pressure oil supplied to the other hydraulic actuator; and return oil from the one hydraulic actuator. A regeneration circuit for re-supplying the hydraulic actuator, and a control means for controlling the hydraulic pump, the detection means, and the regeneration circuit in accordance with an operation amount input to the construction machine, A regenerative valve is provided in an oil passage for re-supplying the return oil to the one hydraulic actuator, and the control means is a load pressure between the first driving pressure and the second driving pressure detected by the detecting means. And a differential pressure calculation unit that calculates a differential pressure between the upstream hydraulic pressure and the downstream hydraulic pressure of the regeneration valve, and the opening of the regeneration valve based on the differential pressure calculated by the differential pressure calculation unit A hydraulic circuit for a construction machine is provided. Further, there is provided a hydraulic circuit for a construction machine, wherein the control means further controls the opening of the regeneration valve by further using a flow rate of pressure oil supplied to the one hydraulic actuator. The regeneration circuit further includes a flow rate control valve for discharging the return oil to the tank, and the control means changes the opening area of the flow rate control valve to change the flow rate of the return oil to be discharged to the tank. Or a hydraulic circuit for a construction machine, wherein the opening degree of the regeneration valve is controlled after the flow control valve is fully closed.

  According to another aspect of the present invention, there is provided a hydraulic circuit for a construction machine that controls operation of a plurality of hydraulic actuators using pressure oil discharged from a hydraulic pump, wherein the hydraulic circuit includes: Detecting means for detecting a first driving pressure of pressure oil supplied to one hydraulic actuator and a second driving pressure of pressure oil supplied to another hydraulic actuator; and return oil from the one hydraulic actuator; A regeneration circuit for re-supplying the one hydraulic actuator; and a control means for controlling the hydraulic pump, the detection means and the regeneration circuit in accordance with an operation amount input to the construction machine, and the regeneration circuit. Is provided with a regeneration valve in an oil passage for re-supplying the return oil to the one hydraulic actuator, and the control means is configured to detect the first drive pressure and the second drive pressure detected by the detection means. A differential pressure calculation unit that calculates a differential pressure between an upstream side hydraulic pressure and a downstream side hydraulic pressure of the regeneration valve based on a load pressure difference, and based on the differential pressure calculated by the differential pressure calculation unit, In the hydraulic circuit of the construction machine, wherein the opening degree is controlled, the regeneration valve is a proportional valve that changes the opening degree according to an input electric signal or pilot pressure, and the control means includes There is provided a hydraulic circuit for a construction machine, wherein the opening degree of the regeneration valve is controlled by controlling the electrical signal or the pilot pressure input to the regeneration valve. Further, there is provided a hydraulic circuit for a construction machine, wherein the first driving pressure is lower than the second driving pressure. Further, the control means further includes an operation determination unit for determining an operation state of the construction machine, and the detection means further detects a bottom pressure and a rod pressure of a hydraulic cylinder of the one hydraulic actuator to determine the operation. The section determines the operation state using the bottom pressure and the rod pressure detected by the detection means, and provides a hydraulic circuit for a construction machine.

  Furthermore, according to another aspect of the present invention, there is provided a hydraulic circuit for a construction machine that controls operation of a plurality of hydraulic actuators using pressure oil discharged from a hydraulic pump, wherein the hydraulic circuit includes: Detecting means for detecting a first driving pressure of pressure oil supplied to one hydraulic actuator and a second driving pressure of pressure oil supplied to another hydraulic actuator; and return oil from the one hydraulic actuator; A regeneration circuit for re-supplying the one hydraulic actuator; and a control means for controlling the hydraulic pump, the detection means and the regeneration circuit in accordance with an operation amount input to the construction machine, and the regeneration circuit. Comprises a regeneration valve in an oil passage for re-supplying the return oil to the one hydraulic actuator, and the control means detects the first drive pressure and the second drive pressure detected by the detection means. A differential pressure calculation unit that calculates a differential pressure between an upstream hydraulic pressure and a downstream hydraulic pressure based on a load pressure difference of the regeneration valve, and the regeneration valve based on the differential pressure calculated by the differential pressure calculation unit In the hydraulic circuit of the construction machine, the control means further includes an operation determination unit that determines an operation state of the construction machine, and the hydraulic actuator of the construction machine is the one hydraulic actuator. The operation of the arm is controlled, the detecting means detects a bottom pressure and a rod pressure of a hydraulic cylinder arranged in the arm, and the operation determining unit is configured to calculate a product of the bottom pressure and a pressure receiving area of the bottom pressure, and Calculate the product of the rod pressure and the pressure receiving area of the rod pressure, respectively, and determine that the excavation state is present when the calculated product related to the bottom pressure exceeds the product related to the rod pressure; State It determines that the hydraulic circuit for a construction machine wherein there is provided that. In addition, the differential pressure calculation unit calculates the differential pressure by further using the excavation pressure of the arm when the operation determination unit determines that the excavation state is present, and the operation determination unit performs When it is determined that there is a hydraulic circuit for a construction machine, the differential pressure is calculated by further using the holding pressure of the arm. Further, the control means gives priority to the operation of the one hydraulic actuator over the other hydraulic actuator by controlling the opening of the regeneration valve, or the other hydraulic actuator over the one hydraulic actuator. There is provided a hydraulic circuit for a construction machine, characterized by prioritizing the operation.

  According to the hydraulic circuit of the construction machine according to the present invention, the hydraulic circuit of the construction machine controls the operation of a plurality of hydraulic actuators, upstream of the regeneration valve disposed in the oil passage for re-supplying the return oil to the hydraulic actuator. The differential pressure between the side and the downstream side can be calculated, and the opening of the regeneration valve can be controlled based on the calculated differential pressure.

1 is a schematic external view illustrating an example of a construction machine according to an embodiment of the present invention. 1 is a schematic hydraulic circuit diagram illustrating an example of a hydraulic circuit of a construction machine according to an embodiment of the present invention. It is a flowchart figure explaining an example of operation of the hydraulic circuit of the construction machine concerning the example of the present invention. It is a general | schematic external view explaining an example of operation | movement of the construction machine which concerns on the Example of this invention. It is a hydraulic circuit diagram explaining the modification of the hydraulic circuit (regeneration circuit) of the construction machine which concerns on the Example of this invention.

  Non-limiting exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the description of all attached drawings, the same or corresponding members or parts are denoted by the same or corresponding reference numerals, and redundant description is omitted. Also, the drawings are not intended to show the relative ratio between members or parts. Accordingly, specific dimensions can be determined by one skilled in the art in light of the following non-limiting embodiments.

  Hereinafter, the present invention will be described using a construction machine 100 including a hydraulic circuit 20 (described later) according to the present embodiment. In addition to the present embodiment, the present invention is a construction machine having a regeneration circuit, and uses a control valve (regeneration valve, proportional valve, flow control valve, etc.) to return the return oil from the hydraulic actuator to the hydraulic actuator. Any supply can be used. Construction machines that can use the present invention include hydraulic excavators, crane cars, bulldozers, wheel loaders and dump trucks, pile driving machines, pile removers, water jets, mud drainage treatment equipment, grout mixers, depth machines. Includes foundation and drilling machines.

(Construction machine configuration)
A schematic configuration of a construction machine 100 in which the present invention can be used will be described with reference to FIG. Here, the construction machine is a machine that performs a desired operation using a hydraulic actuator in the present embodiment.

  As shown in FIG. 1, the construction machine 100 includes, as hydraulic actuators, a boom 11 whose base end is pivotally supported on the upper swing body 10Up, an arm 12 pivotally supported on the distal end of the boom 11, and a distal end of the arm 12. And a bucket 13 that is pivotally supported.

  The construction machine 100 extends and contracts the boom cylinder 11c in the longitudinal direction by supplying hydraulic oil (pressure oil) to the boom cylinder 11c of the boom 11. At this time, the boom 11 is driven in the vertical direction by expansion and contraction of the boom cylinder 11c. Further, the construction machine 100 is controlled in accordance with an operation amount (and an operation direction) of an operation lever (for example, a second operation lever 25b (FIG. 2) described later) of an operator (driver, operator). The hydraulic oil supplied to the boom cylinder 11c (for example, the second hydraulic cylinder 22b (FIG. 2)) is controlled by the control valve (for example, the second direction control valve 21b (FIG. 2)). As a result, the construction machine 100 performs a desired operation according to the operation amount of the operation lever of the operator.

  Similarly to the case of the boom 11, the construction machine 100 drives the arm 12 and the bucket 13 by the expansion and contraction of the arm cylinder 12c and the bucket cylinder 13c. As in the case of the boom cylinder 11c, the construction machine 100 uses the arm cylinder 12c (for example, the first hydraulic pressure) by the arm direction control valve (for example, the first direction control valve 21a (FIG. 2)) and the bucket direction control valve. The hydraulic oil supplied to the cylinder 22a (FIG. 2)) and the bucket cylinder 13c is controlled.

  Further, the construction machine 100 uses the crawler driven by the traveling hydraulic motor provided in the lower traveling body 10Dw to travel the main body of the construction machine 100 (moving back and forth, left and right), and the lower traveling body 10Dw Using the turning device interposed between the upper turning bodies 10Up, the upper turning body 10Up is turned.

  A construction machine 100 that can use the present invention includes a hydraulic circuit 20 (described later) that controls the operation of a plurality of hydraulic actuators using pressure oil (hydraulic oil) discharged from a hydraulic pump. Below, the hydraulic circuit 20 of the construction machine 100 which concerns on embodiment of this invention is demonstrated.

(Hydraulic circuit of construction machinery)
The hydraulic circuit 20 of the construction machine 100 according to the embodiment of the present invention will be described with reference to FIG. Here, the solid line described in FIG. 2 indicates an oil passage (pressure oil passage). In addition, a solid line added with // indicates an electric control system.

  The hydraulic circuit to which the present invention can be applied is not limited to that shown in FIG. That is, the present invention can be applied to any hydraulic circuit provided that it has a regeneration circuit (oil path) for regenerating (re-supplying) return oil and controls the operation of a plurality of hydraulic actuators. The hydraulic circuit 20 shown in FIG. 2 includes two hydraulic cylinders (hydraulic actuators), but the present invention may be applied to a hydraulic circuit including three or more hydraulic cylinders. Furthermore, although the hydraulic circuit 20 shown in FIG. 2 includes one hydraulic pump, the present invention may be applied to a hydraulic circuit used for two or more hydraulic pumps.

  As shown in FIG. 2, in the embodiment, the hydraulic circuit 20 of the construction machine 100 includes a hydraulic pump Pmp mechanically connected to an output shaft of a power source (not illustrated) such as a prime mover, an engine, and a motor, and the hydraulic pump Pmp. Two directional control valves 21 to which pressure oil discharged from the engine is supplied, and two hydraulic cylinders 22 to which pressure oil (hydraulic oil) is supplied via the directional control valve 21. The hydraulic circuit 20 includes a detecting means 23 for detecting the pressure of the pressure oil supplied to the hydraulic cylinder 22 (hereinafter referred to as “driving pressure”), and the return oil from the hydraulic cylinder 22 (hydraulic actuator) as a hydraulic cylinder. And a regenerating circuit 24 for re-supplying the data. Further, the hydraulic circuit 20 controls the hydraulic pump Pmp, the detection unit 23, the regeneration circuit 24, and the like based on the operation amount (and the operation direction) input by the operator using the operation lever 25 (controller 30C). Have

  The hydraulic circuit 20 according to the present embodiment diverts the pressure oil discharged from the hydraulic pump Pmp and supplies (inputs) it to the first directional control valve 21a and the second directional control valve 21b. The hydraulic circuit 20 controls the flow rate and direction of the pressure oil (hydraulic oil) supplied (input) from the direction control valve 21 to the hydraulic cylinder 22 by controlling the operation of the direction control valve 21. Further, in the present embodiment, the hydraulic circuit 20 can resupply (regenerate) the return oil from the first hydraulic cylinder 22a (hydraulic actuator) to the first hydraulic cylinder 22a using the regeneration circuit 24. it can. The hydraulic circuit to which the present invention can be applied may be configured to re-supply the return oil from the second hydraulic cylinder 22b to the second hydraulic cylinder 22.

  The direction control valve 21 supplies hydraulic oil (pressure oil) to the hydraulic cylinder 22. In this embodiment, the direction control valve 21 includes a first direction control valve 21a and a second direction control valve 21b. In this embodiment, the directional control valve 21 controls the operation of the first directional control valve 21a to supply (input) pressure oil (actuation) from the first directional control valve 21a to the first hydraulic cylinder 22a. Oil) flow rate and flow direction. The directional control valve 21 controls the operation of the second directional control valve 21b, thereby supplying pressure oil (hydraulic oil) supplied (input) from the second directional control valve 21b to the second hydraulic cylinder 22b. Control flow and flow direction.

  Here, the directional control valve 21 (for example, the shape of the spool) is used for, for example, an internal passage for supplying pressure oil (hydraulic oil) to the hydraulic cylinder 22 and for returning return oil from the hydraulic cylinder 22 to the tank Tnk. Provide an internal passage. The direction control valve 21 switches the spool position of the direction control valve 21 according to the input remote control pressure (not shown), and changes the path of the internal passage. That is, the direction control valve 21 receives a remote control pressure corresponding to the operation amount of the operation lever 25 operated by the operator, and supplies the flow rate (operation amount) and the flow direction of the hydraulic oil (operating oil) supplied to the hydraulic cylinder 22 ( Operation direction) is changed. The shape of the spool of the directional control valve 21 that can be used in the present invention is not limited to that shown in FIG.

  The hydraulic cylinder 22 drives a hydraulic actuator. In this embodiment, the hydraulic cylinder 22 includes a first hydraulic cylinder 22a and a second hydraulic cylinder 22b. The hydraulic cylinder 22 (first hydraulic cylinder 22a and the like) expands and contracts in the longitudinal direction using hydraulic oil (pressure oil) supplied from the direction control valve 21. Thereby, the hydraulic cylinder 22 drives a hydraulic actuator (for example, the boom 11, the arm 12, and the bucket 13 (FIG. 1)). The pressure oil (operating oil) supplied to the hydraulic cylinder 22 is discharged as return oil to a tank or the like, or supplied (regenerated) to the hydraulic cylinder 22 again using a regeneration circuit 24 described later.

  The hydraulic cylinder 22 can be composed of a cylinder container and a piston. The hydraulic cylinder 22 is supplied with hydraulic oil to a chamber on the bottom side (head side, push side) and a chamber on the rod side (pull side). When hydraulic oil is supplied to the bottom side, the hydraulic cylinder 22 moves a built-in piston or the like in the pushing direction and extends in the longitudinal direction. Further, when hydraulic oil is supplied to the rod side, the hydraulic cylinder 22 moves a built-in piston or the like in the pulling direction and contracts in the longitudinal direction.

  The detection means 23 is a means for detecting the pressure of the pressure oil. In the present embodiment, the detection means 23 is a first pressure sensor 23a1, which detects the pressure of hydraulic oil (hydraulic oil) supplied to the first hydraulic cylinder 22a (hereinafter referred to as “first drive pressure”). 23a2 and second pressure sensors 23b1 and 23b2 for detecting the pressure of hydraulic oil (hydraulic oil) supplied to the second hydraulic cylinder 22b (hereinafter referred to as “second driving pressure”). The detection means 23 can detect the pressures of the pressure oil respectively supplied to the plurality of hydraulic actuators (hydraulic cylinders 22).

  Here, the detecting means 23 can detect the pressure on the bottom side of the hydraulic cylinder 22 (hereinafter referred to as “bottom pressure Pcb”) and the pressure on the rod side (hereinafter referred to as “rod pressure Pcr”). Specifically, as shown in FIG. 2, the detection means 23 can detect the rod pressure Pcr of the first hydraulic cylinder 22a using the first pressure sensor 23a1. Further, the detection means 23 can detect the bottom pressure Pcb of the first hydraulic cylinder 22a using the first pressure sensor 23a2. Furthermore, the detection means 23 can similarly detect the rod pressure Pcr and the bottom pressure Pcb of the second hydraulic cylinder 22b using the second pressure sensors 23b1 and 23b2.

  The regeneration circuit 24 regenerates the return oil from the hydraulic cylinder 22 (hydraulic actuator). In the present embodiment, the regeneration circuit 24 re-supplys (regenerates) return oil from the first hydraulic cylinder 22a to the first hydraulic cylinder 22a. The regeneration circuit 24 includes a regeneration valve 24Vth in an oil passage for resupplying return oil. Here, as the regeneration valve 24Vth, a proportional valve whose opening degree is changed according to an input electric signal or pilot pressure can be used.

  The regeneration circuit 24 further includes a flow rate control valve (meter-out valve) 24Vcq that discharges return oil to the tank Tnk. Here, the flow rate control valve 24Vcq can change the flow rate of the return oil discharged to the tank Tnk by changing its opening area. In the present embodiment, the flow control valve 24Vcq may include an unload position where the opening area is maximized and a block position where the opening area is zero.

  Further, the regeneration circuit 24 may change the opening of the regeneration valve 24Vth and the opening area of the flow control valve 24Vcq according to the load of the hydraulic cylinder 22 (hydraulic actuator). Thereby, the regeneration circuit 24 can re-supply the return oil at a flow rate and pressure corresponding to the load of the hydraulic cylinder 22 (hydraulic actuator).

  The control means 30 is a means for controlling the operation of the construction machine 100 as a whole. The control unit 30 controls the hydraulic pump Pmp, the detection unit 23, the regeneration circuit 24, and the like according to the operation amount (and operation direction) input by the operation lever 25 of the construction machine 100. In this embodiment, the controller 30 uses a controller 30C (FIG. 2) that is mounted to control the operation of the construction machine 100.

  Here, the controller 30C instructs each component of the construction machine 100 to control the operation of each component. The controller 30C can be configured by an arithmetic processing device including a CPU, a memory (ROM, RAM, etc.) and the like.

  The control unit 30 according to the present embodiment includes a differential pressure calculation unit 31 (not shown) that calculates a differential pressure between the upstream hydraulic pressure and the downstream hydraulic pressure (hereinafter referred to as “differential pressure Pv”). Prepare. The control means 30 controls the opening degree of the regeneration valve 24Vth by controlling an electric signal or pilot pressure input to the regeneration valve 24Vth based on the differential pressure Pv calculated by the differential pressure calculation unit 31. Further, the control means 30 may control the opening degree of the regeneration valve 24Vth by further using the flow rate of the pressure oil supplied to the hydraulic cylinder 22 (hydraulic actuator). Furthermore, the control means 30 controls the flow rate of the return oil discharged to the tank Tnk by changing the opening area of the flow rate control valve 24Vcq. The control means 30 can control the opening degree of the regeneration valve 24Vth after the flow rate control valve 24Vcq is fully closed (block position), for example.

  In the present embodiment, the differential pressure calculation unit 31 determines the upstream side hydraulic pressure and the downstream side hydraulic pressure of the regeneration valve based on the load pressure difference between the first driving pressure and the second driving pressure detected by the detecting unit 23. The differential pressure Pv is calculated. The differential pressure calculation unit 31 can calculate the differential pressure Pv of the regenerative valve by further using information related to the operation of the construction machine 100 (for example, excavation pressure, holding pressure). Further, the differential pressure calculation unit 31 may calculate (specify, select, etc.) the differential pressure Pv of the regenerative valve using a mathematical formula, a table, a figure, or the like stored in advance in the construction machine 100. The differential pressure calculation unit 31 may calculate the differential pressure Pv using a CPU and a memory mounted on the controller 30C and the like.

  According to the hydraulic circuit 20 of the construction machine 100 according to the embodiment of the present invention, when the regeneration circuit 24 is used to simultaneously operate a plurality of hydraulic actuators of the construction machine 100 (hereinafter referred to as “during complex operation”). In order to ensure the operability of the low load side hydraulic actuator, the return oil can be supplied again to the low load side hydraulic actuator. According to the hydraulic circuit 20, in order to ensure the operability of the arm 12 on the low load side, for example, during the combined operation of simultaneously performing the closing operation of the arm 12 (FIG. 1) and the raising operation of the boom 11 (FIG. 1), The return oil can be supplied again to the drive side (for example, the bottom side) of the hydraulic cylinder 22a (FIG. 2) of the arm 12. Thereby, according to the hydraulic circuit 20, the operativity of the low load side at the time of compound operation is securable.

  Further, according to the hydraulic circuit 20 according to the present embodiment, the opening area of the flow control valve 24Vcq can be controlled using the control means 30 before the opening degree of the regeneration valve 24Vth is controlled. For example, the control means 30 can set the flow control valve 24Vcq to the block position before controlling the opening of the regeneration valve 24Vth. As a result, according to the hydraulic circuit 20, the entire amount of oil can be supplied (input) to the regeneration valve 24Vth. That is, according to the hydraulic circuit 20, it is possible to regenerate the entire amount of return oil without using the flow rate control valve 24Vcq to discharge the return oil to the tank Tnk.

  Furthermore, according to the hydraulic circuit 20 according to the present embodiment, the entire amount of return oil can be regenerated using the regeneration valve 24Vth, the flow rate control valve 24Vcq, and the like, so that the pressure oil discharged from the hydraulic cylinder 22 (return oil) Can be used effectively. That is, according to the hydraulic circuit 20, the return oil can be regenerated using the regeneration circuit 24, so that the discharge flow rate (pressure oil flow rate) of the hydraulic pump Pmp necessary for the operation of the construction machine 100 can be reduced. it can. Thereby, according to the hydraulic circuit 20, since the discharge flow rate (pressure oil flow rate) of the hydraulic pump Pmp can be reduced, the loss (for example, differential pressure × flow rate) relating to the discharge flow rate can be reduced.

  Furthermore, the hydraulic circuit 20 (control unit 30) of the construction machine 100 according to the embodiment of the present invention may perform an operation that does not regenerate the return oil in the case of (1) or (2) below.

  (1) When the excavation pressure is about half of the maximum pressure (drive pressure) and more excavation force is required.

  (2) When the load pressure difference is smaller than the excavation pressure and the check valve Vch or the like inhibits the flow of the returned oil.

  The hydraulic circuit 20 (control unit 30) according to the present embodiment switches the meter-out opening (flow rate control valve 24Vcq) from the closed position to the open position, and in the above (1), the loss is reduced as a sufficient opening and the above ( In 2), a composite operation may be secured by generating a pressure loss corresponding to the load pressure difference.

  As described above, according to the hydraulic circuit 20 of the construction machine 100 according to the embodiment of the present invention, when controlling the operation of the plurality of hydraulic actuators, the upstream side and the downstream side of the regeneration valve 24Vth arranged in the regeneration circuit 24 And the opening degree of the regeneration valve 24Vth can be controlled based on the calculated differential pressure Pv. Further, according to the hydraulic circuit 20 according to the present embodiment, the opening degree of the regeneration valve 24Vth can be controlled based on the calculated differential pressure Pv, so that the operability of the low load side hydraulic actuator can be improved during combined operation. In order to ensure, return oil can be re-supplied to the hydraulic actuator on the low load side. That is, according to the hydraulic circuit 20 according to the present embodiment, it is possible to ensure the operability on the low load side during the combined operation. Further, according to the hydraulic circuit 20 according to the present embodiment, the discharge flow rate (pressure oil flow rate) of the hydraulic pump Pmp at the time of combined operation can be reduced, so that the loss related to the discharge flow rate can be reduced.

  In addition, according to the hydraulic circuit 20 according to the present embodiment, the discharge flow rate of the hydraulic pump Pmp at the time of combined operation can be reduced. The pressure loss generated in the hydraulic circuit can be reduced as compared with a case where a throttle is provided on the upstream side of the load side (for example, the meter-in opening is throttled).

  Furthermore, according to the hydraulic circuit 20 according to the present embodiment, when the return oil is regenerated (when the opening of the regeneration valve 24Vth is controlled) and when the meter-out opening is controlled (the opening of the flow control valve 24Vcq) In either case of controlling the area), the low load side can be set to the same pressure as the high load side. Further, according to the hydraulic circuit 20 according to the present embodiment, the low load hydraulic actuator or the high load hydraulic actuator is prioritized by controlling the opening of the regeneration valve 24Vth and the opening area of the flow control valve 24Vcq. Can work.

  The present invention will be described using examples of the construction machine 110 including the hydraulic circuit 20 according to the embodiment.

(Configuration of construction machine) and (Hydraulic circuit of construction machine)
The construction of the construction machine 110 and the hydraulic circuit 20 according to this embodiment are shown in FIGS. In addition, since the structure etc. of the construction machine 110 which concerns on a present Example are fundamentally the same as the structure of the construction machine 100 which concerns on embodiment, a different part is mainly demonstrated.

  The control means 30 of the construction machine 110 according to the present embodiment further includes an operation determination unit 32 (not shown) that determines the operation state of the construction machine 110. Here, in this embodiment, the operation determining unit 32 determines the operation of the arm 12 among the plurality of hydraulic actuators. The operation determination unit 32 that can use the present invention may determine an operation of a hydraulic actuator other than the arm 12.

  Specifically, the operation determination unit 32 (control unit 30) firstly has the bottom pressure Pcb and rod pressure of the hydraulic cylinder (for example, the first hydraulic cylinder 22a in FIG. 2) corresponding to the arm 12 detected by the detection unit 23. The detection result of Pcr is acquired. Next, the operation determination unit 32 calculates the “product Fcb” of the acquired “bottom pressure Pcb” and “the pressure receiving area Acb of the bottom pressure Pcb” and the “rod pressure Pcr” and “the pressure receiving area Acr of the rod pressure Pcr”. “Product Fcr” is calculated respectively. Next, when the calculated “product Fbb related to the bottom pressure” exceeds the “product Fcr related to the rod pressure”, the operation determination unit 32 can determine that the arm 12 (the construction machine 110) is in the “digging state”. . Further, when the calculated “product Fbb related to the bottom pressure” is equal to or less than the “product Fcr related to the rod pressure”, the operation determination unit 32 can determine that the arm 12 is in the “self-weight drop state”.

  The differential pressure calculation unit 31 of the control unit 30 according to the present embodiment calculates the differential pressure Pv by further using the excavation pressure of the arm 12 when the operation determination unit 32 determines that the excavation state is in effect. Can do. In addition, the differential pressure calculation unit 31 can calculate the differential pressure Pv by further using the holding pressure of the arm 12 when the operation determination unit 32 determines that it is in the “self-weight drop state”. The operation in which the differential pressure calculation unit 31 calculates the differential pressure Pv will be described later (an operation to regenerate the return oil).

(Operation to regenerate the return oil)
The operation in which the hydraulic circuit 20 of the construction machine 110 according to the embodiment of the present invention regenerates the return oil will be described with reference to FIGS. 3 and 4. Here, in the following description, the combined operation is a case where the operation in the closing direction Ma of the arm 12 and the operation in the raising direction Mb of the boom 11 are simultaneously performed as shown in FIG. The combined operation to which the present invention can be applied is not limited to the above operation.

  As shown in FIG. 3, the construction machine 110 starts a combined operation using the control means 30 or the like in step S301. After the start, the construction machine 110 proceeds to step S302.

  In step S302, the construction machine 110 uses the control means 30 to control the discharge flow rate of the hydraulic pump Pmp. Thereafter, the construction machine 110 proceeds to step S303. Here, the control means 30 can control the discharge flow rate of the hydraulic pump Pmp based on the operation amount and the operation direction input by the operator using the operation lever 25. In addition, the control unit 30 may further control the discharge flow rate of the hydraulic pump Pmp based on the operation amount and the operation direction input by the operator using the control map or the like stored in the construction machine 110 in advance. .

  Next, in step S <b> 303, the construction machine 110 detects the driving pressure using the detection unit 23. After the detection, the construction machine 110 proceeds to step S304. Here, the detection means 23 detects the first drive pressure Pd1 and the second drive pressure Pd2 using the first pressure sensors 23a1, 23a2, the second pressure sensors 23b1, 23b2 (FIG. 2), and the like. be able to.

  Next, in step S <b> 304, the construction machine 110 uses the control unit 30 to calculate the load pressure difference Pm based on the driving pressure detected by the detection unit 23. After the calculation, the construction machine 110 proceeds to step S305. Here, the control means 30 can calculate the load pressure difference Pm using the first drive pressure Pd1 and the second drive pressure Pd2 detected by the detection means 23 in step S303. The control means 30 may calculate the load pressure difference Pm using, for example, the following equation.

(Equation 1)
Pm = Pd1-Pd2
In step S305, the construction machine 110 detects the bottom pressure Pcb and the rod pressure Pcr of the hydraulic cylinder 22 connected to the regeneration circuit using the detection unit 23. After the detection, the construction machine 110 proceeds to step S306. Specifically, the detection means 23 can detect the bottom pressure Pcb and the rod pressure Pcr of the first hydraulic cylinder 22a using the first pressure sensors 23a1 and 23a2.

  In step S <b> 306, the construction machine 110 determines the operation state of the construction machine 110 using the operation determination unit 32 of the control unit 30. Here, the construction machine 110 proceeds to step S307A when the operation determining unit 32 determines that the “self-weight falling state” is set. When the operation determining unit 32 determines that the construction machine 110 is in the “excavation state”, the construction machine 110 proceeds to step S307B.

  In step S307A, the construction machine 110 calculates the differential pressure Pv on the upstream side and the downstream side of the regeneration valve 24Vth using the differential pressure calculation unit 31 of the control means 30. After the calculation, the construction machine 110 proceeds to step S308. Here, the differential pressure calculation unit 31 can calculate the differential pressure Pv using, for example, the following equation. Note that Psp in Equation 2 is the holding pressure of the arm 12 in this embodiment.

(Equation 2)
Pv = Pm−Psp + Pm × 2
For example, if the holding pressure Psp is 4 MPa, the load pressure difference Pm is 5 MPa, and the pressure receiving area of the cylinder is twice the bottom side of the rod side, the differential pressure Pv is −9 MPa.

  On the other hand, in step S307B, the construction machine 110 uses the differential pressure calculation unit 31 to calculate the differential pressure Pv between the upstream side and the downstream side of the regeneration valve 24Vth. After the calculation, the construction machine 110 proceeds to step S308. Here, the differential pressure calculation unit 31 can calculate the differential pressure Pv using, for example, the following equation. Note that Pdg in Equation 3 is the excavation pressure of the arm 12 in this embodiment.

(Equation 3)
Pv = Pm + Pdg−Pm × 2
For example, if the excavation pressure Pdg is 4 MPa, the load pressure difference Pm is 5 MPa, and the pressure receiving area of the cylinder is twice the bottom side of the rod side, the differential pressure Pv is −1 MPa.

  In step S308, the construction machine 110 controls the operation of the regeneration valve 24Vth and the flow control valve 24Vcq using the control means 30. Thereafter, the construction machine 110 proceeds to step S309. Here, the control means 30 controls the opening degree of the regeneration valve 24Vth based on the differential pressure Pv calculated in step S307A or step S307B. In the present embodiment, the control means 30 fully closes the flow control valve 24Vcq before controlling the opening degree of the regeneration valve 24Vth. As a result, the construction machine 110 (hydraulic circuit 20) can resupply (regenerate the entire amount) return oil to the hydraulic actuator (hydraulic cylinder 22).

  Here, the control means 30 can calculate the opening A corresponding to the differential pressure Pv using, for example, the following equation (orifice equation). In Equation 4, Q is the flow rate of the pressure oil, k is a flow coefficient corresponding to the shape of the opening of the regeneration valve 24Vth, and ΔP is the absolute value of the differential pressure Pv calculated in Step S307A or Step S307B.

(Equation 4)
A = Q / (k · ΔP ^1/2 )
Next, in step S309, the construction machine 110 uses the control unit 30 to determine whether to end the combined operation. When the construction machine 110 does not end the combined operation (when the operation is continued), the construction machine 110 returns to step S302. When ending the combined operation, the construction machine 110 proceeds to END in the drawing, and ends the operation of regenerating the return oil.

  As described above, according to the hydraulic circuit 20 of the construction machine 110 according to the present embodiment, the same effect as that of the hydraulic circuit 20 of the construction machine 100 according to the embodiment can be obtained.

  Further, according to the hydraulic circuit 20 according to the present embodiment, the opening degree of the regeneration valve 24Vth can be controlled based on the calculated differential pressure Pv, so that the closing operation of the arm 12 and the raising operation of the boom 11 are performed simultaneously. In the combined operation, the return oil can be supplied again to the arm 12 (arm hydraulic cylinder) in order to ensure the operability of the closing operation of the arm 12 on the low load side. That is, according to the hydraulic circuit 20 according to the present embodiment, it is possible to ensure the operability of the low load side hydraulic actuator during the combined operation. Moreover, according to the hydraulic circuit 20 according to the present embodiment, the same effect as described above can be obtained when the load pressure difference Pm is higher than the excavation pressure Pdg in the case of a low-load excavation operation. Furthermore, according to the hydraulic circuit 20 according to the present embodiment, by controlling the opening of the regeneration valve 24Vth and the opening area of the flow control valve 24Vcq, the operation on the low load side (for example, the arm closing) or the operation on the high load side. It is possible to operate with priority (for example, boom raising).

(Modification 1)
The present invention will be described using a first modification of the hydraulic circuit 20 of the construction machine 110 according to the first embodiment. Note that the configuration of the hydraulic circuit according to the present modification has the same parts as the configuration of the hydraulic circuit 20 according to the first embodiment, and therefore different parts will be mainly described.

(Hydraulic circuit of construction machinery)
FIG. 5A shows a regeneration circuit of the hydraulic circuit according to this modification.

  As shown in FIG. 5A, in the hydraulic circuit according to this modification, the regeneration valve 24Vth is disposed in the oil path between the direction control valve 21a and the bottom side of the hydraulic cylinder 22a. In the hydraulic circuit according to this modification, the holding valve Vsp is disposed in the oil path between the direction control valve 21a and the rod side of the hydraulic cylinder 22a.

  Here, the holding valve Vsp is a poppet valve controlled by the control means 30 (controller 30C) in the present modification. The holding valve Vsp restricts the operation of the arm 12 in the closing direction. That is, the holding valve Vsp prevents the arm 12 from performing an unplanned closing operation by blocking the flow of pressure oil flowing out of the rod-side chamber of the hydraulic cylinder 22a of the arm 12.

  With the above configuration, according to the hydraulic circuit according to this modification, the same effect as the hydraulic circuit 20 of the construction machine 110 according to the first embodiment can be obtained.

(Modification 2)
The present invention will be described using a second modification of the hydraulic circuit 20 of the construction machine 110 according to the first embodiment. Note that the configuration of the hydraulic circuit according to the present modification has the same parts as the configuration of the hydraulic circuit 20 according to the first embodiment, and therefore different parts will be mainly described.

(Hydraulic circuit of construction machinery)
FIG. 5B shows a regeneration circuit for the hydraulic circuit according to this modification.

  As shown in FIG. 5B, in the hydraulic circuit according to this modification, the regeneration valve 24Vth is disposed in an oil path that bypasses the two oil paths between the direction control valve 21a and the hydraulic cylinder 22a. In the hydraulic circuit according to this modification, the holding valve Vsp is disposed in the oil path between the direction control valve 21a and the rod side of the hydraulic cylinder 22a. Further, in the hydraulic circuit according to this modification, the flow control valve 24Vcq is disposed in the oil passage between the direction control valve 21a and the holding valve Vsp. In the regeneration circuit of this modification, the holding valve 58 and the flow control valve 24Vcq may be integrally formed.

  With the above configuration, according to the hydraulic circuit according to the present modification, it is possible to obtain the same effects as those of the hydraulic circuit 20 of the construction machine 110 according to the first embodiment and the first modification.

  The preferred embodiments and examples of the present invention including the hydraulic circuit of the construction machine have been described above, but the present invention is not limited to the above-described embodiments or examples. The present invention can be variously modified or changed in light of the appended claims.

DESCRIPTION OF SYMBOLS 100: Construction machine 10: Hydraulic actuator 11: Boom, 11c: Boom cylinder 12: Arm, 12c: Arm cylinder 13: Bucket, 13c: Bucket cylinder 20: Hydraulic circuit 21: Directional control valve (control valve)
21a: first directional control valve, 21b: second directional control valve 22: hydraulic cylinder 22a: first hydraulic cylinder, 22b: second hydraulic cylinder 23: detecting means 23a1, 23a2: first pressure sensor, 23b1, 23b2: second pressure sensor 24: regeneration circuit 24Vth: regeneration valve (proportional valve)
24Vcq: Meter-out valve (flow control valve)
25: Operation lever 25a: First operation lever 25b: Second operation lever 30: Control means, 30C: Controller 31: Differential pressure calculation unit 32: Operation determination unit Pmp: Hydraulic pump Tnk: Hydraulic oil tank
Vch: Check valve (load check)
Vsp: Holding valve Pd1, Pd2: Drive pressure Pm: Load pressure difference Pv: Differential pressure Pcb: Bottom pressure Pcr: Rod pressure Psp: Holding pressure Pdg: Drilling pressure

Claims (10)

A hydraulic circuit of a construction machine that controls the operation of a plurality of hydraulic actuators using pressure oil discharged from a hydraulic pump,
Detecting means for detecting a first driving pressure of pressure oil supplied to one of the plurality of hydraulic actuators and a second driving pressure of pressure oil supplied to another hydraulic actuator;
A regeneration circuit for re-supplying the return oil from the one hydraulic actuator to the one hydraulic actuator;
Control means for controlling the hydraulic pump, the detection means, and the regeneration circuit according to an operation amount input to the construction machine,
The regeneration circuit includes a regeneration valve in an oil passage for resupplying the return oil to the one hydraulic actuator,
The control means calculates a differential pressure between the upstream hydraulic pressure and the downstream hydraulic pressure of the regeneration valve based on a load pressure difference between the first drive pressure and the second drive pressure detected by the detection means. A differential pressure calculation unit for controlling the opening of the regeneration valve based on the differential pressure calculated by the differential pressure calculation unit,
A hydraulic circuit of a construction machine characterized by the above.   2. The hydraulic circuit for a construction machine according to claim 1, wherein the control unit further controls an opening degree of the regeneration valve by further using a flow rate of pressure oil supplied to the one hydraulic actuator. 3. The regeneration circuit further includes a flow control valve that discharges the return oil to a tank,
The control means controls the flow rate of the return oil discharged to the tank by changing an opening area of the flow rate control valve.
The hydraulic circuit for a construction machine according to claim 1, wherein the hydraulic circuit is for a construction machine.   4. The hydraulic circuit for a construction machine according to claim 3, wherein the control means controls the opening of the regeneration valve after the flow control valve is fully closed. The regeneration valve is a proportional valve that changes its opening according to an input electric signal or pilot pressure,
The control means controls the opening degree of the regeneration valve by controlling the electric signal or the pilot pressure input to the regeneration valve.
The hydraulic circuit for a construction machine according to any one of claims 1 to 4, wherein the hydraulic circuit is for a construction machine.   6. The hydraulic circuit for a construction machine according to claim 1, wherein the first driving pressure is lower than the second driving pressure. The control means further includes an operation determination unit that determines an operation state of the construction machine,
The detecting means further detects a bottom pressure and a rod pressure of a hydraulic cylinder of the one hydraulic actuator;
The operation determination unit determines the operation state using the bottom pressure and the rod pressure detected by the detection unit.
The hydraulic circuit for a construction machine according to any one of claims 1 to 6, wherein the hydraulic circuit is for a construction machine. The control means further includes an operation determination unit that determines an operation state of the construction machine, and controls the operation of the arm of the construction machine as the one hydraulic actuator,
The detecting means detects a bottom pressure and a rod pressure of a hydraulic cylinder disposed in the arm;
The operation determining unit calculates a product of the bottom pressure and the pressure receiving area of the bottom pressure and a product of the rod pressure and the pressure receiving area of the rod pressure, and the calculated product related to the bottom pressure relates to the rod pressure. When it exceeds the product, it is determined that it is in the excavation state, otherwise it is determined that it is in its own weight drop state,
The hydraulic circuit for a construction machine according to any one of claims 1 to 6, wherein the hydraulic circuit is for a construction machine. The differential pressure calculation unit calculates the differential pressure by further using the excavation pressure of the arm when the operation determination unit determines that the excavation state is present, and the operation determination unit is in the dead weight lowering state. Calculating the differential pressure by further using the holding pressure of the arm when judged;
The hydraulic circuit for a construction machine according to claim 8.   The control means gives priority to the operation of the one hydraulic actuator over the other hydraulic actuator by controlling the opening of the regeneration valve, or the operation of the other hydraulic actuator over the one hydraulic actuator. The hydraulic circuit for a construction machine according to any one of claims 1 to 9, wherein priority is given to.

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