Construction machine

Abstract

To provide a construction machine that can reduce flow dividing loss at the time of combined operation while securing a necessary speed of actuators.SOLUTION: Direction switching valves 23 and 27 for a first actuator 1 belong to a first valve group 20a sharing a first bypass line 51. Direction switching valves 24 and 26 for a second actuator 3 belong to a second valve group 20b sharing a second bypass line 52. A construction machine comprises a first cut valve 31 capable of opening / closing the first bypass line 51 downstream of the first valve group 20a, a second cut valve 32 capable of opening / closing the second bypass line 52 downstream of the second valve group 20b, and a plurality of switching valves 41a-41d and 42a-42d capable of switching respective connection destinations of a plurality of discharge ports comprised in pump devices 11 and 12, to the first bypass line 51 or the second bypass line 52.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a construction machine such as a hydraulic excavator. [Background technology]

[0002] The two-pump, two-valve hydraulic circuit system, which has two hydraulic pumps and a control valve consisting of two valve groups, is widely used as a hydraulic circuit system for hydraulic excavators. Hydraulic circuit systems are further classified into open center and closed center types based on the structure of the control valve.

[0003] An example of a prior art document disclosing a two-pump, two-valve open-center hydraulic circuit device is Patent Document 1. Patent Document 1 describes a configuration that enables smooth boom lifting during combined operation of the boom, arm, and bucket.

[0004] The hydraulic circuit system described in Patent Document 1 is provided with two boom direction switching valves and two arm direction switching valves, and the boom direction switching valves and arm direction switching valves are arranged in both the first valve group connected to the first pump and the second valve group connected to the second pump. This allows the boom cylinder and arm cylinder to each be supplied with a flow rate equivalent to that of two pumps at maximum, enabling high-speed operation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-13547 Summary of the Invention [Problem to be solved by the invention]

[0006] In the hydraulic circuit system described in Patent Document 1, when the boom and arm are operated in a combined manner, oil discharged from a first hydraulic pump is supplied to the boom cylinder via the first boom direction switching valve and simultaneously supplied to the arm cylinder via the first arm direction switching valve, and oil discharged from a second hydraulic pump is supplied to the boom cylinder via the second boom direction switching valve and simultaneously supplied to the arm cylinder via the second arm direction switching valve. Here, assuming that the load pressure on the boom cylinder is 20 MPa and the load pressure on the arm cylinder is 5 MPa, both the first and second hydraulic pumps must discharge hydraulic oil at 20 MPa or more to match the higher load pressure. The pressure oil supplied to the arm cylinder is reduced from 20 MPa or more to 5 MPa by throttling the meter-in passage of the arm direction switching valve. The energy loss caused by this throttling is called shunt loss and is a factor that inhibits the energy efficiency of hydraulic excavators.

[0007] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a construction machine that can reduce shunt loss during combined operation while ensuring the required actuator speed. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a pump device driven by the prime mover, the pump device having a plurality of discharge ports whose discharge flow rates can be individually controlled, a plurality of actuators, a plurality of directional control valves that control the flow of pressure oil supplied from the pump device to the plurality of actuators, a plurality of operating devices that generate operation signals for driving the plurality of actuators, and a controller that controls the pump device and the plurality of directional control valves in accordance with inputs from the plurality of operating devices, wherein the plurality of directional control valves are respectively arranged on a first bypass line or a second bypass line, and the directional control valves of the plurality of directional control valves that are arranged on the first bypass line constitute a first valve group, and the directional control valves of the plurality of directional control valves that are arranged on the second bypass line constitute a second valve group. In a construction machine constituting a group, the plurality of actuators include a first actuator and a second actuator, a directional switching valve for the first actuator among the plurality of directional switching valves belongs to the first valve group, and a directional switching valve for the second actuator among the plurality of directional switching valves belongs to the second valve group, the construction machine is equipped with a first cut valve capable of opening and closing the first bypass line downstream of the first valve group, a second cut valve capable of opening and closing the second bypass line downstream of the second valve group, and a plurality of switching valves capable of switching the connection destination of each of the plurality of discharge ports to the first bypass line or the second bypass line, and the controller controls the first cut valve, the second cut valve, and the plurality of switching valves in accordance with inputs from the plurality of operating devices.

[0009] According to the present invention configured as described above, the required speed of each actuator can be ensured by merging the pressure oil discharged from each discharge port of the pump device into the first bypass line or the second bypass line via multiple selector valves. Furthermore, by consolidating the directional control valves for the first actuator 1 in the first valve group and the directional control valves for the second actuator in the second valve group, pressure oil discharged from one discharge port is not divided between the first actuator 1 and the second actuator 3, preventing branch flow loss during combined operation in which the first actuator and the second actuator are driven simultaneously. [Effects of the Invention]

[0010] According to the present invention, in a construction machine, it is possible to reduce shunt loss during combined operation while ensuring the required speed of the actuator. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing a hydraulic excavator according to an embodiment of the present invention; [Figure 2] A diagram showing a two-pump, two-valve open center hydraulic circuit device mounted on a hydraulic excavator in the prior art. [Figure 3] FIG. 1 is a diagram showing a hydraulic circuit device mounted on a hydraulic excavator according to an embodiment of the present invention. [Figure 4] 1 is a diagram showing the operating characteristics of a pump device, a directional control valve, and a cut valve according to an embodiment of the present invention; [Figure 5] Schematic diagram showing a part of an electronically commutated pump device incorporating a pump element. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a hydraulic excavator will be described as an example of a construction machine according to an embodiment of the present invention with reference to the drawings. In each drawing, the same reference numerals are used to designate the same components, and redundant description will be omitted where appropriate.

[0013] 1 is a diagram showing a hydraulic excavator according to this embodiment. The hydraulic excavator 100 includes a lower traveling body 101 having a crawler-type traveling device 7, and an upper rotating body 102 rotatably mounted on the lower traveling body 101 via a rotating device (not shown). The traveling device 7 is driven by a hydraulic traveling motor 8, and the upper rotating body 102 is driven by a hydraulic rotating motor (not shown).

[0014] A cab 9 for the operator is provided on the front left side of the upper rotating body 102. A boom 2 is rotatably connected to the front right side of the upper rotating body 102. The boom 2 is driven by a boom cylinder 1 consisting of a single-rod hydraulic cylinder. An arm 4 is rotatably connected to the tip of the boom 2. The arm 4 is driven by an arm cylinder 3 consisting of a single-rod hydraulic cylinder. A bucket 6 is rotatably connected to the tip of the arm 4. The bucket 6 is driven by a bucket cylinder 5 consisting of a single-rod hydraulic cylinder.

[0015] FIG. 2 is a diagram showing a two-pump, two-valve open center type hydraulic circuit device mounted on a hydraulic excavator according to the prior art.

[0016] The first hydraulic pump 18 and the second hydraulic pump 19 are variable displacement pumps having regulators 18a, 19a, and are driven by the engine 10, which is a prime mover. The regulators 18a, 19a change the displacements (discharge amounts per rotation) of the hydraulic pumps 18, 19 in response to commands from the controller 57, thereby changing the discharge flow rates of the hydraulic pumps 18, 19.

[0017] The discharge port of first hydraulic pump 18 is connected to a first bypass line 51, which is, for example, a center bypass line. Arranged in first bypass line 51, in this order from the upstream side, are a right-travel directional control valve 21, a bucket directional control valve 22, a first boom directional control valve 23, and a second arm directional control valve 24. The directional control valves 21 to 24, which share first bypass line 51, form a first valve group 20a.

[0018] The discharge port of the second hydraulic pump 19 is connected to a second bypass line 52, which may be, for example, a center bypass line. Arranged in the second bypass line 52, in this order from the upstream side, are a swing direction switching valve 25, a first arm direction switching valve 26, a second boom direction switching valve 27, a standby direction switching valve 28, and a left traveling direction switching valve 29. The direction switching valves 25 to 29, which share the second bypass line 52, form a second valve group 20b.

[0019] Each of the directional control valves 21 to 29 is formed with a center bypass passage, a meter-in passage, and a meter-out passage. When the directional control valves 21 to 24 are in the neutral position, the center bypass passage is opened to release the second bypass line, and oil discharged from the first hydraulic pump 18 flows into the tank 55. Similarly, when the directional control valves 25 to 29 are in the neutral position, the center bypass passage is opened to release the second bypass line 52, and oil discharged from the second hydraulic pump 19 flows into the tank 55. When the directional control valves 21 to 29 are switched from the neutral position to either the left or right position, the center bypass passage is narrowed and the meter-in passage is opened, and oil discharged from the hydraulic pumps 18 and 19 is supplied to the actuators 1, 3, 5, and 8 via the meter-in passage, and hydraulic oil discharged from the actuators 1, 3, 5, and 8 flows into the tank 55 via the meter-out passage.

[0020] The controller 57 outputs commands to the control valve 20 according to inputs from a plurality of operation levers (only the boom operation lever 56a and the arm operation lever 56b are shown) and sensor information (engine speed, pressure of each part, etc.).

[0021] 2, the required speed of the actuators 1 and 3 can be ensured by combining the oil discharged from the two hydraulic pumps 18 and 19 and supplying it to the actuators 1 and 3. However, when performing combined operation of the boom 2 and arm 4, flow division loss occurs due to the restriction of the meter-in passages of the arm directional control valves 24 and 26. Also, energy loss occurs due to the bleed-off flow rate in order to lubricate and protect the sliding parts of the hydraulic pumps 18 and 19 and to ensure the responsiveness of the actuators 1, 3, 5, and 8.

[0022] 3 is a diagram showing a hydraulic circuit system mounted on the hydraulic excavator 100 of this embodiment. The following description will focus on the differences from a conventional hydraulic circuit system (shown in FIG. 2).

[0023] 3, in control valve 20A, the positions of second arm direction switching valve 24 and second boom direction switching valve 27 are swapped compared to the conventional control valve 20, with the two boom direction switching valves 23, 27 concentrated in a first valve group 20a and the two arm direction switching valves 24, 26 concentrated in a second valve group 20b. In addition, a first cutoff valve 31 capable of opening and closing a first bypass line 51 is provided downstream of first valve group 20a, and a second cutoff valve 32 capable of opening and closing a second bypass line 52 is provided downstream of second valve group 20b.

[0024] The first pump device 11 and the second pump device 12 are configured as digital pumps capable of changing the discharge flow rate by controlling the on / off of solenoid valves (not shown). The first pump device 11 has four discharge ports, and the discharge flow rate of each discharge port can be individually controlled by four pump elements 11a to 11d contained therein. Similarly, the second pump device 12 has four discharge ports, and the discharge flow rate of each discharge port can be individually controlled by four pump elements 12a to 12d contained therein. Each pump element is configured so that it does not discharge pressure oil when its corresponding solenoid on / off valve (not shown) is off, and discharges pressure oil at a flow rate corresponding to the pump rotation speed when the solenoid on / off valve is on. Therefore, the flow rate of pressure oil discharged from each discharge port can be individually controlled by changing the frequency and timing of turning on and off these solenoid valves. In the case of typical variable displacement pumps, such as swash plate pumps and bent axis pumps, the response time is on the order of hundreds of milliseconds because they drive a tilting mechanism with a large inertia, whereas the response time of a digital pump is on the order of several milliseconds to several tens of milliseconds, which is similar to the response time of an electromagnetic on / off valve. Therefore, by configuring pump devices 11 and 12 with digital pumps, higher response performance can be achieved than with typical variable displacement pumps. In addition, because digital pumps have fewer sliding parts at high speed, the bleed-off flow rate during standby for lubrication can be reduced compared to typical variable displacement pumps.

[0025] The discharge ports of the pump elements 11a to 11d and 12a to 12d are connected to a switching valve block 40. The switching valve block 40 has switching valves 41a to 41d and 42a to 42. The connection destination of the discharge ports of the pump elements 11a to 11d and 12a to 12d can be switched to either the first bypass line 51 or the second bypass line 51 via the switching valves 41a to 41d and 42a to 42d. This makes it possible to individually switch the supply destination of the discharge oil of the pump elements 11a to 11d and 12a to 12d.

[0026] In the hydraulic circuit configuration of the switching valve block 40 in this embodiment, the oil discharged from the first pump device 11 is supplied to the first bypass line 51 when no command is output to the switching valves 41a to 41d, and is supplied to the second bypass line 52 when a command is output to the switching valves 41a to 41d. On the other hand, the oil discharged from the second pump device 12 is supplied to the second bypass line 52 when no command is output to the switching valves 42a to 42d, and is supplied to the first bypass line 51 when a command is output to the switching valves 42a to 42d.

[0027] Controller 57 outputs commands to pump controllers 58, 59, switching valves 41a-41d, 42a-42d, and control valve 20A in response to inputs from multiple operating devices (only boom operating lever 56a and arm operating lever 56b are shown) and sensor information (engine speed, pressure of various parts, etc.). Pump controllers 58, 59 are controllers dedicated to digital pumps, and output commands to the electromagnetic on / off valves of pump devices 11, 12 in response to commands from controller 57 to control the discharge flow rate.

[0028] 4 is a diagram showing the operating characteristics of pump devices 11, 12, directional control valves 21 to 29, and cut valves 31, 32. The horizontal axis represents the lever operation amount, and the upper diagram represents the valve opening area and the lower diagram represents the flow rate.

[0029] In the above diagram, the solid lines show the characteristics of the bypass line opening area in directional control valves 21 to 29. The bypass line opening area gradually decreases as the directional control valves 21 to 29 are displaced from the neutral position in response to an increase in the amount of lever operation, and becomes zero when the amount of lever operation is X3 or greater. The dashed-dotted line shows the meter-in opening area to the actuator. The meter-in opening area to the actuator becomes zero when the amount of lever operation is X2 or less, and gradually increases when the amount of lever operation exceeds X2.

[0030] In the diagram below, the dashed-dotted line represents the pump flow rate in a conventional hydraulic circuit system. Conventional pumps discharge a constant minimum flow rate Q1, even when the pump is in standby mode with no lever input (when the lever operation amount is less than X1). This is to protect the lubrication of the pump's sliding parts and ensure responsiveness when the actuator starts to move. The pump flow rate begins to increase when the lever operation amount exceeds a certain value, and gradually increases in accordance with the lever operation amount. This is a control method known as positive control. The thick solid line is an example of the characteristics of the meter-in flow rate to the actuator. When the bypass line is not closed (when the lever operation amount is between 0 and X3), some of the pump discharge oil also flows to tank 55 via the bypass line, so the pump flow rate must be greater than the meter-in flow rate to the actuator. As a result, the hatched area represents the bleed-off flow rate, which impedes energy savings.

[0031] Therefore, in this embodiment, when the lever operation amount exceeds X1, as shown by the dashed line in the upper diagram, the cut valves 31 and 32 are closed. As shown by the thick line in the lower diagram, the pump flow rate is set to a minute flow rate Q0, which is smaller than the minimum flow rate Q1, until the lever operation amount reaches X2. When the lever operation amount is X2 or greater, the flow rate is set to the same as the actuator's meter-in flow rate (required flow rate). This reduces the bleed-off flow rate during standby and makes it possible to set the bleed-off flow rate during half lever operation and full lever operation to zero. Furthermore, as described above, this embodiment uses a digital pump that provides high response on the order of several milliseconds to several tens of milliseconds. Therefore, even if the pump discharge flow rate during standby is minute, it can instantly respond to lever operation and discharge the required flow rate, ensuring responsiveness when the actuator starts moving.

[0032] Next, the operation of the hydraulic circuit system when performing combined operation of the boom 2 and arm 4 will be described with reference to Figure 3. When the boom operation lever 56a is operated, the cut valve 31 closes, the first boom direction switching valve 23 and the second boom direction switching valve 27 are displaced from their neutral positions, and the boom cylinder 1 is driven by pressure oil from the first pump unit 11. When the arm operation lever 56b is operated, the cut valve 32 closes, the first arm direction switching valve 26 and the second arm direction switching valve 24 are displaced from their neutral positions, and the arm cylinder 3 is driven by pressure oil from the second pump unit 12. When the boom operation lever 56a and the arm operation lever 56b are operated simultaneously, these operations are performed simultaneously.

[0033] Because the boom cylinder 1 and the arm cylinder 3 are driven by pump elements 11a-11d and 12a-12d that do not overlap with one another, each pump element 11a-11d and 12a-12d only needs to discharge hydraulic oil at the minimum pressure appropriate for the load on each connected actuator 1, 3. For example, if the load pressure on the boom cylinder 1 is 20 MPa and the load pressure on the arm cylinder 3 is 5 MPa, and assuming a pressure loss of about 1 MPa in the piping and valves, the first pump device 11 only needs to supply a pressure of about 21 MPa, and the second pump device 12 only needs to supply a pressure of about 6 MPa. In this way, by driving the multiple actuators 1, 3 that have widely different load pressures with pump elements 11a-11d and 12a-12d that do not overlap with one another, there is no need to significantly reduce the pump discharge pressure by extremely narrowing the meter-in passage of the directional control valve, as in conventional hydraulic circuit systems, and this makes it possible to reduce branch flow loss.

[0034] Furthermore, for example, if the required flow rate of boom cylinder 1 cannot be met by first pump device 11 alone, for example, by switching selector valve 42a, the flow rate of pump element 12a of second pump device 12 can be merged into boom cylinder 1. Furthermore, by switching selector valves 42a to 42d, the entire flow rate of second pump device 12 can be merged into boom cylinder 1. In this way, in this embodiment, all eight discharge ports can be connected to boom cylinder 1 or arm cylinder 3, so that an actuator speed equivalent to that of a conventional two-pump system can be ensured if the total pump capacity is approximately the same.

[0035] The configuration of the pump devices 11 and 12 will be described in detail below. Each of the pump devices 11 and 12 includes a pump shaft and at least three working chambers whose working volume 202 changes periodically as the pump shaft rotates. Each working chamber of the pump devices 11 and 12 has a low-pressure valve that controls the flow of hydraulic oil between the working chamber and a low-pressure manifold, and a high-pressure valve that controls the flow of hydraulic oil between the working chamber and a high-pressure manifold extending to a discharge port. The working chambers are formed in a plurality of pump elements. Each pump element contains one or more working chambers (typically two or more working chambers) and is connected to a high-pressure manifold 213 that is common to each working chamber in the pump element and communicates with the discharge port. The pump controller 58 (59) is configured to actively control at least the low pressure valve 209 of the working chamber in phase correlation with the cycle of the working volume 202 to determine whether, during each cycle of the working volume 202, each working chamber will undergo an active cycle involving movement of hydraulic oil between the low pressure manifold and high pressure manifold of the working chamber, or an inactive cycle without movement of hydraulic oil between the low pressure manifold and high pressure manifold of the working chamber, so that the change in the working volume 202 of each pump element through each high pressure manifold to each discharge port is controlled according to each demand for hydraulic oil.

[0036] 5 is a schematic diagram showing a portion of an electronically commutated pumping device 11, 12 incorporating pump elements. The pumping device 11 (12) includes a plurality of working chambers each having a cylinder 201 with a working volume 202 defined by the cylinder's inner surface, and a piston 203 driven relative to a pump shaft 204 by an eccentric cam 205, reciprocating within the cylinder to periodically vary the working volume 202 of the cylinder. A shaft position and / or speed sensor 206 determines the instantaneous angular position and / or rotational speed of the pump shaft 204 and transmits this to a pump controller 58 (59) via a signal line 208. This allows the pump controller 58 (59) to determine the instantaneous phase of each cylinder's cycle.

[0037] Each actuating chamber is associated with a low-pressure valve 209, which comprises an electrically actuated face-sealing poppet valve. The low-pressure valve 209 is associated with one actuating chamber and is operable to selectively block a passageway extending from the actuating chamber to a low-pressure manifold 210. The low-pressure manifold 210 may connect one or more actuating chambers, or indeed all of the actuating chambers of the pump element as illustrated here, to tank 55 (shown in FIG. 3). The low-pressure valves 209 are normally open, solenoid-operated valves that passively open to communicate between the actuating chambers and the low-pressure manifold 210 when the pressure in the actuating chamber is equal to or less than the pressure in the low-pressure manifold 210 (i.e., during the intake stroke), but can be selectively closed via a low-pressure valve control line 211 to disconnect the actuating chambers from the low-pressure manifold 210 under active control of the pump controller 58 (59). Alternatively, the low-pressure valves 209 may be normally closed valves.

[0038] Each actuation chamber is further associated with a high-pressure valve 212, which comprises a pressure-actuated discharge valve. The high-pressure valves 212 are configured to open outward from their respective actuation chambers and are operable to block the respective flow paths extending from the actuation chambers to a high-pressure manifold 213. The high-pressure manifold 213 connects the actuation chambers within the pump elements and directs hydraulic fluid from the actuation chambers within the pump elements to a discharge port 214. The high-pressure valves 212 function as normally closed pressure-relief check valves that passively open due to a pressure differential across the valve, combined with the force of a biasing member within the valve. In some embodiments, the high-pressure valves 212 also function as normally closed electromagnetically actuated check valves that, when opened by pressure within the associated actuation chamber, can be selectively held open by the pump controller 58 (59) via a high-pressure valve control line 215. Typically, the high-pressure valves 212 cannot be opened by the pump controller 58 (59) against pressure within the high-pressure manifold 213. The high-pressure valve 212 may further be openable or partially openable under the control of the pump controller 58 (59) when pressure is present in the high-pressure manifold 213 but not in the working chamber.

[0039] In pump mode, the pump controller 58 (59) selects the flow of hydraulic fluid from the working chambers to the high-pressure manifold 213 by the pumping devices 11, 12 by actively closing one or more low-pressure valves 209, typically near the maximum volume point in the cycle of the associated working chamber, to close the path to the low-pressure manifold 210, thereby directing hydraulic fluid out through the associated high-pressure valve 212 (but not actively opening the high-pressure valve 212) on the subsequent contraction stroke, creating a valid cycle with hydraulic fluid movement. Alternatively, the low-pressure valve 209 may remain open throughout the working chamber cycle (or seal the working chamber throughout the cycle), creating a invalid cycle with no hydraulic fluid movement. To satisfy the flow demand from the pump elements, the pump controller 58 (59) selects the number and order of valid and invalid cycles so that the working chambers of the pump elements connected to the same high-pressure manifold 213 and discharge port 214 produce flow or torque or power to satisfy the selected hydraulic fluid flow rate.

[0040] The pump controller 58 (59) is operable not only to decide for each cycle whether to close or leave the low pressure valve 209 open, thereby selecting between an effective and ineffective cycle, but also to vary the exact phasing of the closure of the low pressure valve 209 and / or high pressure valve 212 relative to the changing working volume 202, thereby selecting the flow rate of hydraulic fluid from the high pressure manifold 213 to the low pressure manifold 210 (or vice versa).

[0041] The arrows on the low pressure manifold 210 and high pressure manifold 213 indicate the flow of hydraulic fluid in motor mode, with the flow being reversed in pump mode.

[0042] 5, all working chambers are connected to the same high-pressure manifold 213 and discharge port 214, but typically pumping devices 11, 12 further comprise working chambers forming one or more separate pump elements with their own high-pressure manifold 213, discharge port 214, and demand signal. The demand signal may use any suitable units. In one known example, the demand signal is expressed in terms of a volumetric rate of change F, which is the maximum possible volumetric change per revolution of the pump shaft 204. d The target flow rate is expressed as the volumetric change rate F d and the rotational speed of the pump shaft 204.

[0043] (summary) In this embodiment, the system includes a prime mover 10, pump devices 11 and 12 that have a plurality of discharge ports that can individually control the discharge flow rate and are driven by the prime mover 10, a plurality of actuators 1, 3, 5, and 8, a plurality of directional control valves 21 to 29 that control the flow of pressure oil supplied from the pump devices 11 and 12 to the plurality of actuators 1, 3, 5, and 8, a plurality of operating devices 56a and 56b that generate operating signals for driving the plurality of actuators 1, 3, 5, and 8, and a plurality of control signals for controlling the input of the plurality of operating devices 56a and 56b. and a controller 57 that controls the pump devices 11, 12 and the plurality of directional control valves 21-29 accordingly. The plurality of directional control valves 21-29 are respectively arranged on a first bypass line 51 or a second bypass line 52. Of the plurality of directional control valves 21-29, the directional control valves 21-23, 27 arranged on the first bypass line 51 constitute a first valve group, and of the plurality of directional control valves 21-29, the directional control valves 24-26, 28, 29 arranged on the second bypass line 52 constitute a second valve group. In the construction machine 100 that constitutes the valve group, the multiple actuators 1, 3, 5, 8 include a first actuator 1 and a second actuator 3, and among the multiple directional control valves 21 to 29, the directional control valves 23 and 27 for the first actuator 1 belong to a first valve group 20a, and among the multiple directional control valves 21 to 29, the directional control valves 24 and 26 for the second actuator 3 belong to a second valve group 20b, and the construction machine 100 has a first bypass line downstream of the first valve group 20a. The second valve group 20b is provided with a first cut valve 31 that can open and close the second bypass line 51, a second cut valve 32 that can open and close the second bypass line 52 downstream of the second valve group 20b, and a plurality of switching valves 41a to 41d, 42a to 42d that can switch the connection destination of each of the plurality of discharge ports to the first bypass line 51 or the second bypass line 52, and a controller 57 controls the first cut valve 31, the second cut valve 32, and the plurality of switching valves 41a to 41d, 42a to 42d in accordance with input from a plurality of operating devices 56a, 56b.

[0044] According to the present embodiment configured as described above, the pressure oil discharged from each discharge port of pump devices 11 and 12 is merged into first bypass line 51 or second bypass line 52 via multiple switching valves 41a-41d and 42a-42d, thereby ensuring the required speed of each of actuators 1, 3, 5, and 8. Furthermore, by consolidating directional control valves 23 and 27 for first actuator 1 into first valve group 20a and directional control valves 24 and 26 for second actuator 3 into second valve group 20b, pressure oil discharged from one discharge port is not divided between first actuator 1 and second actuator 3, thereby preventing flow loss during combined operation in which first actuator 1 and second actuator 3 are simultaneously driven. While pump devices 11 and 12 are configured as digital pumps with multiple discharge ports in this embodiment, they may also be configured as variable displacement pumps with multiple discharge ports or multiple variable displacement pumps with one discharge port.

[0045] Furthermore, the controller 57 in this embodiment coordinates and controls the flow of pressure oil from the first cut valve 31, the second cut valve 32, the multiple switching valves 41a to 41d, 42a to 42d, and the pump devices 11, 12 to the first bypass line 51 and the second bypass line 52, respectively, in response to inputs from the multiple operating devices 56a, 56b. This makes it possible to realize the operation of the construction machine 100 in accordance with the operator's intentions.

[0046] Furthermore, in this embodiment, the controller 57 controls the first cutoff valve 31 to close the first bypass line 51 downstream of the first valve group 20a before the pump devices 11 and 12 are controlled to supply pressure oil to the first valve group 20a, and / or controls the second cutoff valve 32 to close the second bypass line 52 downstream of the second valve group 20b before the pump devices 11 and 12 are controlled to supply pressure oil to the second valve group 20b. This reduces the bleed-off flow rate to zero when the actuators 1, 3, 5, and 8 are being driven, thereby enabling improved energy savings.

[0047] Furthermore, in this embodiment, the controller 57 closes the first cutoff valve 31 when a first operation signal amount, which is an input amount of the multiple operating devices 56a and 56b to the first actuator 1, exceeds a first threshold X1. When the first operation signal amount exceeds a second threshold X2, which is greater than the first threshold X1, the controller 57 controls the pump devices 11 and 12 so that the discharge flow rate of one or more of the multiple discharge ports connected to the first valve group 20a matches the required flow rate of the first actuator 1, which is set in accordance with the first operation signal amount. When a second operation signal amount, which is an input amount of the multiple operating devices 56a and 56b to the second actuator 3, exceeds the first threshold X1, the controller 57 closes the second cutoff valve 32. When the second operation signal amount exceeds the second threshold X2, the controller 57 controls the pump devices 11 and 12 so that the discharge flow rate of one or more of the multiple discharge ports connected to the second valve group 20b matches the required flow rate of the second actuator 3, which is set in accordance with the second operation signal amount. This reduces the bleed-off flow rate when the actuators 1 and 3 are driven to zero, thereby further improving energy efficiency.

[0048] Furthermore, the multiple directional control valves 21 to 29 in this embodiment are multiple open center type directional control valves 21 to 29. As a result, in a construction machine 100 equipped with a hydraulic circuit device including open center type directional control valves 21 to 29, it is possible to reduce branch loss during combined operation while ensuring the required speed of the actuators 1, 3.

[0049] In this embodiment, the first bypass line 51 and the second bypass line 52 are each configured as a center bypass line. This makes it possible to reduce branch loss during combined operation while ensuring the required speed of the actuators 1 and 3 in a construction machine 100 equipped with a hydraulic circuit system in which multiple directional control valves 21 to 29 are arranged on a center bypass line.

[0050] Furthermore, in this embodiment, the first cut valve 31 and the second cut valve 32 are each configured as a proportional flow valve or an on-off valve, which makes it possible to reduce the bleed-off flow rate by the first cut valve 31 and the second cut valve 32 configured as a proportional flow valve or an on-off valve.

[0051] Furthermore, the construction machine 100 in this embodiment is equipped with a pump controller 58 (59) that controls the pump device 11 (12), and the pump device 11 (12) has a pump shaft 204 and three or more working chambers whose working volume 202 changes periodically as the pump shaft 204 rotates, and the working chambers have a low-pressure valve that controls the flow of hydraulic oil between the working chambers and a low-pressure manifold 210 and a high-pressure valve that controls the flow of hydraulic oil between the working chambers and a high-pressure manifold 213, and the working chambers are formed into a plurality of pump elements, and each of the plurality of pump elements contains one or more of the working chambers and a high-pressure manifold that is common to the containing working chambers and communicates with a discharge port 214. The pump controller 58 (59) is connected to the low-pressure manifold 210 and the high-pressure manifold 213, and is configured to actively control at least the low-pressure valve 209 of the working chamber in phase correlation with the cycle of the working volume 202 to determine whether the working chamber will undergo an effective cycle involving movement of hydraulic oil between the low-pressure manifold 210 and the high-pressure manifold 213 or an ineffective cycle not involving movement of hydraulic oil between the low-pressure manifold 210 and the high-pressure manifold 213 in each cycle of the working volume 202 so that the change in the working volume 202 from the high-pressure manifold 213 to the discharge port 214 is controlled in accordance with each required flow rate of hydraulic oil to be discharged from the discharge port 214. This makes it possible to reduce the bleed-off flow rate during standby to improve energy saving and to improve the responsiveness of each actuator 1, 3, 5, 8.

[0052] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the described configurations. [Explanation of symbols]

[0053] 1... boom cylinder (first actuator), 2... boom, 3... arm cylinder (second actuator), 4... arm, 5... bucket cylinder (actuator), 6... bucket, 7... traveling device, 8... traveling hydraulic motor (actuator), 9... cab, 10... engine (prime mover), 11... first pump device, 11a to 11d... pump elements, 12... second pump device, 12a to 12d... pump elements, 18... first hydraulic pump, 18a ...regulator, 19...second hydraulic pump, 19a...regulator, 20, 20A...control valve, 20a...first valve group, 20b...second valve group, 21...direction switching valve for right travel, 22...direction switching valve for bucket, 23...direction switching valve for first boom, 24...direction switching valve for second arm, 25...direction switching valve for swing, 26...direction switching valve for first arm, 27...direction switching valve for second boom, 28...backup directional switching valve, 29...left travel Directional switching valve, 31...first cut valve, 32...second cut valve, 40...switching valve block, 41a to 41d...switching valve, 42...switching valve, 42a to 42d...switching valve, 51...first bypass line (center bypass line), 52...second bypass line (center bypass line), 55...tank, 56a...boom operation lever (operation device), 56b...arm operation lever (operation device), 57...controller, 58, 59...pump controller, 10 0...hydraulic excavator (construction machinery), 101...lower running body, 102...upper rotating body, 201...cylinder, 202...working volume, 203...piston, 204...pump shaft, 205...eccentric cam, 206...shaft position and / or speed sensor, 208...signal line, 209...low pressure valve, 210...low pressure manifold, 211...low pressure valve control line, 212...high pressure valve, 213...high pressure manifold, 214...discharge port, 215...high pressure valve control line.

Claims

1. The prime mover, a pump device having a plurality of discharge ports each capable of individually controlling a discharge flow rate, the pump device being driven by the prime mover; A plurality of actuators; a plurality of directional control valves for controlling the flow of pressure oil supplied from the pump device to the plurality of actuators; A plurality of operation devices that generate operation signals for driving the plurality of actuators; a controller for controlling the pump device and the plurality of directional control valves in response to inputs from the plurality of operation devices; The plurality of directional control valves are each disposed on a first bypass line or a second bypass line, Among the plurality of directional control valves, a directional control valve arranged on the first bypass line constitutes a first valve group, In a construction machine in which a directional control valve arranged on the second bypass line among the plurality of directional control valves constitutes a second valve group, the plurality of actuators includes a first actuator and a second actuator; Among the plurality of directional control valves, a directional control valve for the first actuator belongs to the first valve group, Among the plurality of directional control valves, a directional control valve for the second actuator belongs to the second valve group, The construction machine includes: a first cut valve downstream of the first valve group and capable of opening and closing the first bypass line; a second cut valve downstream of the second valve group and capable of opening and closing the second bypass line; a plurality of switching valves capable of switching the connection destinations of the plurality of discharge ports to the first bypass line or the second bypass line, The controller controls the first cut valve, the second cut valve, and the plurality of switching valves in response to inputs from the plurality of operating devices. A construction machine characterized by:

2. 2. The construction machine according to claim 1, The controller controls the first cut valve, the second cut valve, the plurality of switching valves, and the flow of pressure oil from the pump device to the first bypass line and the second bypass line in a coordinated manner in response to inputs from the plurality of operating devices. A construction machine characterized by:

3. The construction machine according to claim 1 or 2, The controller: controlling the first cut-off valve to close the first bypass line downstream of the first valve group before the pump device is controlled to supply pressure oil to the first valve group; and / or before the pump device is controlled to supply pressure oil to the second valve group, the second cut valve is controlled to close the second bypass line downstream of the second valve group. A construction machine characterized by:

4. The construction machine according to any one of claims 1 to 3, The controller: closing the first cut valve when a first operation signal amount, which is an input amount of the plurality of operation devices to the first actuator, exceeds a first threshold value; when the first operation signal amount exceeds a second threshold value that is greater than the first threshold value, controlling the pump device so that a discharge flow rate of one or more discharge ports connected to the first valve group among the plurality of discharge ports matches a required flow rate of the first actuator that is set in accordance with the first operation signal amount; closing the second cut valve when a second operation signal amount, which is an input amount of the plurality of operation devices to the second actuator, exceeds the first threshold value; When the second operation signal amount exceeds the second threshold value, the pump device is controlled so that a discharge flow rate of one or more discharge ports connected to the second valve group among the plurality of discharge ports matches a required flow rate of the second actuator set in accordance with the second operation signal amount. A construction machine characterized by:

5. The construction machine according to any one of claims 1 to 4, The plurality of directional control valves are a plurality of open center type directional control valves. A construction machine characterized by:

6. The construction machine according to claim 5, The first bypass line and the second bypass line are each configured as a center bypass line. A construction machine characterized by:

7. The construction machine according to any one of claims 1 to 6, The first cut valve and the second cut valve are each configured as a proportional flow valve or an on-off valve. A construction machine characterized by:

8. The construction machine according to any one of claims 1 to 7, A pump controller for controlling the pump device, The pump device includes a pump shaft and three or more working chambers whose working volumes change periodically with rotation of the pump shaft; The working chamber has a low pressure valve that controls the flow of hydraulic oil between the working chamber and a low pressure manifold, and a high pressure valve that controls the flow of hydraulic oil between the working chamber and a high pressure manifold, The working chamber is formed in a plurality of pump elements, Each of the plurality of pump elements includes one or more of the working chambers, and is connected to the high-pressure manifold that is common to the working chambers and communicates with a discharge port; The pump controller is configured to actively control at least the low pressure valve of the working chamber in phase correlation with the cycle of the working volume to determine whether, during each cycle of the working volume, the working chamber undergoes an active cycle involving movement of hydraulic fluid between the low pressure manifold and the high pressure manifold, or an inactive cycle involving no movement of hydraulic fluid between the low pressure manifold and the high pressure manifold, such that the change in the working volume through the high pressure manifold to the discharge port is controlled in response to a required flow rate of hydraulic fluid to be discharged from the discharge port. A construction machine characterized by:

Images