Work machine

Abstract

The purpose of the present invention is to suppress shock caused by frequent switching between a non-confluence state and a confluence state of pressure oil from two hydraulic pumps. This work machine is provided with: a hydraulic drive device that includes a first hydraulic pump, a second hydraulic pump, a first hydraulic actuator, and a flow converging valve that converges pressure oil and communicates the pressure oil to the first hydraulic actuator; an operation member; and a controller that controls the flow collecting valve so as to supply the pressure oil from the first hydraulic pump to the first hydraulic actuator while the operation member reaches the first position from the initial position, and controls the flow collecting valve so as to supply the pressure oil from the first hydraulic pump to the first hydraulic actuator when the operation member is operated in a direction in which the amount of operation increases beyond the first position. When the operation member reaches a first position, the flow collecting valve is controlled so as to supply the combined pressure oil to the first hydraulic actuator, and when the operation member reaches a second position closer to the initial position than the first position from an arbitrary position exceeding the first position, the flow collecting valve is controlled so as to supply the pressure oil from the first hydraulic pump to the first hydraulic actuator.

Description

Technical Field

[0001] The present invention relates to working machines such as hydraulic excavators. Background Art

[0002] Generally speaking, in a hydraulic system used in a hydraulic excavator or other working machine, there are actuators that use one of two hydraulic pumps as a supply source and actuators that use both hydraulic pumps as supply sources. In an actuator that uses both hydraulic pumps as supply sources, the priority of the two hydraulic pumps is often predetermined for each actuator from the viewpoint of reducing flow splitting and throttling losses.

[0003] In this hydraulic system, for example, a hydraulic pump assigned a first priority is predetermined as a main pump, and a hydraulic pump assigned a second priority is predetermined as a slave pump. When a target flow is within the range of the supplyable flow of the main pump, pressurized oil is only supplied from the main pump to the actuator, and pressurized oil is only supplied from the slave pump to the actuator when the target flow exceeds the supplyable flow of the main pump.

[0004] At this time, when the pressure of the actuator of the merging object is higher than the pressure of other actuators, the discharge pressure of the sub-pump changes according to whether there is a merging or not. Therefore, when the target flow rate increases or decreases near the upper limit of the supplyable flow rate of the main pump, the repeated changes in the discharge pressure accompanied by the switching between the merging state and the non-merging state may cause action shock, operational discomfort, control instability, etc.

[0005] Therefore, in Patent Document 1, when the difference between the rod-side pressure and the cover-side pressure of the hydraulic cylinder (actuator), that is, the driving pressure, is below a specified value, the first hydraulic pump and the second hydraulic pump are controlled in a connected state, thereby suppressing the generation of action shock caused by switching between the connected state (merging state) and the non-merging state (non-merging state).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent No. 6145229 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, in Patent Document 1, the controller controls the pump connection state according to whether the required flow rate is above a certain threshold value or whether the driving pressure is above a certain threshold value. Therefore, when the required flow rate and the driving pressure increase or decrease near the threshold value, there is a situation where the confluent state and the non-confluent state are repeatedly switched. Therefore, when the driving pressure is high, the confluent state and the non-confluent state are repeatedly switched, which may cause discomfort in operation and instability in control. In addition, under flow conditions where confluence is not required, if the driving pressure is below a specified value, the confluent state is also maintained. Therefore, during complex operations in the aerial action of the working machine (for example, when operating the boom and the dipper arm at the same time in the air), unnecessary throttling losses are generated, which may lead to deterioration of fuel economy.

[0011] An object of the present invention is to provide a working machine capable of reducing the split-flow throttling loss and suppressing the shock caused by the frequent switching between the non-merging state and the merging state of the pressure oil from two hydraulic pumps.

[0012] Means for solving problems

[0013] 14. The hydraulic press of claim 13 wherein the control valve further comprises a controllable valve configured to control the flow of hydraulic fluid from the first hydraulic pump to the first hydraulic actuator and a control valve configured to control the flow of hydraulic fluid from the first hydraulic pump to the first hydraulic actuator. non-merging state), when the operating member is operated in the direction of increasing the operating amount beyond the first position, the merging valve is controlled to merge the pressure oil from the second hydraulic pump with the pressure oil from the first hydraulic pump, and the merged pressure oil is supplied to the first hydraulic actuator according to the increase of the operating amount (merging state), when the operating member is operated in the direction of reducing the operating amount from any position beyond the first position and reaches a second position closer to the initial position than the first position, the merging valve is controlled to release the merging of the pressure oil from the first hydraulic pump and the pressure oil from the second hydraulic pump, and the pressure oil from the first hydraulic pump is supplied to the first hydraulic actuator according to the decrease of the operating amount.

[0014] Effects of the Invention

[0015] According to the working machine of the present invention, it is possible to reduce the split throttling loss and suppress the impact caused by the frequent switching of the non-merging state and the merging state of the pressure oil from the two hydraulic pumps. In addition, the above-mentioned problems, structures and effects are clarified by the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a side view showing the appearance of the hydraulic excavator.

[0017] Figure 2 It is a hydraulic circuit diagram showing the hydraulic system.

[0018] Figure 3 It is the functional block diagram of the controller.

[0019] Figure 4 This is a diagram showing changes in flow rate, pressure, and flow splitting and throttling loss relative to the boom operation amount in the prior art.

[0020] Figure 5 This is a diagram showing changes in flow rate with respect to the boom operation amount in the first embodiment.

[0021] Figure 6 It is a flowchart showing the procedure of the control processing of the controller.

[0022] Figure 7 It is a diagram showing changes in the flow rate with respect to the boom operation amount in a modified example.

[0023] Figure 8 It is a flowchart showing the procedure of the control processing of the controller according to the second embodiment.

[0024] Fig. 9 1 is a flowchart showing a procedure of control processing by the controller according to the third embodiment. DETAILED DESCRIPTION

[0025] (First Embodiment)

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0027] Figure 1 1 is a side view showing the appearance of a hydraulic excavator as an example of a working machine of the present invention. Figure 1 In the figure, the hydraulic excavator 1 has: a lower traveling body 3, an upper revolving body 2 rotatably provided on the lower traveling body 3, and a cab 10. A boom 4, an arm 6, and a bucket 8 constituting a front working machine are mounted on the upper revolving body 2, and are driven by a boom cylinder 5, an arm cylinder 7, and a bucket cylinder 9 as hydraulic actuators, respectively. In addition, an attachment not shown in the figure can be installed on the hydraulic excavator 1.

[0028] Here, the boom cylinder 5 corresponds to a first hydraulic actuator of the present invention, and the arm cylinder 7 corresponds to a second hydraulic actuator of the present invention.

[0029] Figure 2 1 is a hydraulic circuit diagram of a hydraulic drive device HD mounted on the hydraulic excavator 1. Here, a circuit of a hydraulic system for driving the boom cylinder 5, the arm cylinder 7, the attachment 1 cylinder 24, and the attachment 2 cylinder 25 will be described.

[0030] The hydraulic drive device HD is composed of the following parts: a controller 20 for controlling the operation of the hydraulic actuators 5, 7, 24, 25, an operating lever 21 for transmitting an electrical signal to the controller 20, a first hydraulic pump 17 and a second hydraulic pump 18 for supplying working oil to the hydraulic actuators 5, 7, 24, 25, a pilot pump 19 for supplying working oil to drive each switching valve, an engine 52 for driving the first hydraulic pump 17, the second hydraulic pump 18 and the pilot pump 19, a control valve 16 for controlling the flow rate and direction of the working oil supplied to the hydraulic actuators 5, 7, 24, 25, and a working oil tank 26 for storing the working oil.

[0031] The operating lever (operating member) 21 is mounted on the cab 10 where the operator sits, and includes an operating lever that can be tilted forward, backward, left, and right, and a detection device that electrically detects an operation signal corresponding to the tilting amount of the operating lever (lever operation amount), and outputs the lever operation amount detected by the detection device to the controller 20 via an electrical wiring. That is, the operation of each hydraulic actuator 5, 7, 24, 25 is distributed in the front-back direction or left-right direction of each operating lever of the operating lever 21.

[0032] The first hydraulic pump 17 and the second hydraulic pump 18 are driven by the engine 52 , and discharge the hydraulic oil stored in the hydraulic oil tank 26 toward the hydraulic actuators 5 , 7 , 24 , and 25 as pressurized oil.

[0033] The pilot pump 19 is driven by the engine 52 together with the first hydraulic pump 17 and the second hydraulic pump 18 , and discharges the hydraulic oil stored in the hydraulic oil tank 26 toward the switching valves 41 , 42 , and 43 as pressurized oil.

[0034] In addition, in the present embodiment, electromagnetic proportional valves are exemplified as the switching valves 41, 42, and 43, but other types of valves may also be used. In addition, although not shown, the switching valves and the relief valves of the hydraulic actuators other than the boom cylinder 5, namely the arm cylinder 7, the attachment 1 cylinder 24, and the attachment 2 cylinder 25 are also switched by electromagnetic proportional valves.

[0035] The control valve 16 is provided between the first hydraulic pump 17 and the second hydraulic pump 18 and the boom cylinder 5, the arm cylinder 7, the attachment cylinder 1 24, and the attachment cylinder 2 25. The control valve 16 receives a command signal from a controller 20 corresponding to an operating lever 21, and controls the supply, discharge, and stop of the pressure oil relative to the boom cylinder 5, the arm cylinder 7, the attachment cylinder 1 24, and the attachment cylinder 2 25.

[0036] The control valve 16 is composed of the following parts: pump confluence valves 28, 29, 31, 32, 34, 35, 37, 38 for controlling the supply flow from each hydraulic pump 17, 18, direction switching valves 27, 30, 33, 36 for switching the direction of the pressure oil supplied from the pump confluence valves 28, 29, 31, 32, 34, 35, 37, 38 to each cylinder 5, 7, 24, 25 and the pressure oil discharged from each cylinder 5, 7, 24, 25 to the working oil tank 26, and relief valves 39, 40 for controlling the flow discharged from each hydraulic pump 17, 18 to the working oil tank 26.

[0037] The control valve 16 forms a first pump line 53 connected to the first hydraulic pump 17 and a second pump line 54 connected to the second hydraulic pump 18. The boom pump 1 merging valve 28, the arm pump 1 merging valve 31, the attachment 1 pump 1 merging valve 34, and the attachment 2 pump 2 merging valve 37 are connected in parallel from the first pump line 53. Similarly, the boom pump 2 merging valve 29, the arm pump 2 merging valve 32, the attachment 1 pump 2 merging valve 35, and the attachment 2 pump 2 merging valve 38 are connected in parallel from the second pump line 54.

[0038] The operations of the cylinders 5 , 7 , 24 , and 25 are basically the same, and therefore, the operation of the boom cylinder 5 will be described below.

[0039] The boom pump 1 confluence valve 28 is pilot operated by the electromagnetic proportional valve 42 to control the supply flow rate from the first hydraulic pump 17 so that the pressure oil flows to the downstream direction switching valve 27. The boom pump 2 confluence valve 29 is pilot operated by the electromagnetic proportional valve 43 to control the supply flow rate from the second hydraulic pump 18 so that the pressure oil flows to the downstream direction switching valve 27. The controller 20 controls the flow rate through each pump confluence valve 28, 29 to control whether the pressure oil is supplied to the boom cylinder 5 only from the first hydraulic pump 17, or only from the second hydraulic pump 18, or whether the pressure oil of the first hydraulic pump 17 and the second hydraulic pump 18 are confluenced and supplied (switching control between the confluence state and the non-confluence state).

[0040] The pressure oil supplied from the hydraulic pumps 17 and 18 through the pump confluence valves 28 and 29 is supplied to the bottom side and the rod side of the boom cylinder 5 through the boom direction switching valve 27. In addition, the pressure oil discharged from the bottom side and the pressure oil discharged from the rod side are discharged to the working oil tank 22 through the boom direction switching valve 27. As a result, the boom cylinder 5 performs a telescopic operation.

[0041] The electromagnetic proportional valve 41 is connected to the pilot pump 19 via the pilot primary pressure line 55. In addition, the electromagnetic proportional valve 41 is connected to the pilot oil chamber provided at one end side of the boom direction switching valve 27 via the pilot secondary pressure line 56. Similarly, the electromagnetic proportional valve 42 is connected to the pilot oil chamber provided at one end side of the boom pump 1 confluence valve 28, and the electromagnetic proportional valve 43 is connected to the pilot oil chamber provided at one end side of the boom pump 2 confluence valve 29.

[0042] Furthermore, when the operator tilts the operating lever 21 from the initial position (neutral position) to the working position, the controller 20 outputs a command signal corresponding to the operation amount to the electromagnetic proportional valve 41 through the electromagnetic proportional valve command circuit 57. Then, the electromagnetic proportional valve 41 controls the pressure of the pilot pressure oil supplied from the pilot primary pressure pipeline 55 in accordance with the command signal. Furthermore, the pilot pressure oil whose pressure is controlled by the electromagnetic proportional valve 41 is supplied and discharged to the pilot oil chamber of the boom direction switching valve 27 via the pilot secondary pressure pipeline 56. Similarly, the pilot pressure oil is also supplied and discharged to the pilot oil chambers of the boom pump 1 confluence valve 28 and the boom pump 2 confluence valve 29.

[0043] As a result, the boom pump 1 merging valve 28 , the boom pump 2 merging valve 29 , and the boom direction switching valve 27 are driven, and the pressurized oil is supplied to and discharged from the boom cylinder 5 .

[0044] Next, the function of the controller 20 will be described. Figure 3 is a functional block diagram of the controller 20. Figure 3 As shown, the controller 20 includes a required flow rate calculation unit 61 , a pump dischargeable flow rate calculation unit 63 , and a valve control unit 60 .

[0045] The required flow rate calculation unit 61 calculates the actuator required flow rate by taking the lever operation amount of the operating lever 21 as input, and outputs the actuator required flow rate to the valve control unit 60. Specifically, the required flow rate calculation unit 61 calculates the actuator required speed from the lever operation amount, and calculates the actuator required flow rate from the actuator required speed.

[0046] The pump dischargeable flow rate calculation unit 63 calculates the pump dischargeable flow rate using the pump pressure from the pump pressure sensors 49 and 50 as input, and outputs the pump dischargeable flow rate to the valve control unit 60. Specifically, the pump dischargeable flow rate calculation unit 63 calculates the maximum flow rate that the hydraulic pump can discharge within a range that does not exceed a torque limit value determined based on the pump pressure.

[0047] The valve control unit 60 calculates the command current to each spool-use electromagnetic proportional valve using the actuator required flow rate, the pump dischargeable flow rate and the boom pressure (actuator load pressure) from the boom pressure sensors 44A and 44B as inputs, and outputs the command current to each electromagnetic proportional valve.

[0048] The valve control section 60 is composed of a priority pump recording section 64 , a direction switching valve control section 66 , a pump confluence valve control section 67 , and a relief valve control section 68 .

[0049] The main pump (first priority pump) of each actuator 5, 7, 24, 25 is set in the priority pump recording unit 64. The main pump is set to a setting that does not cause discomfort when a standard usage is assumed. For example, it is as follows.

[0050] (1) The main pumps are separated by two actuators with high frequency of use. (For example, the main pump for the boom cylinder 5 is the first hydraulic pump 17, and the main pump for the arm cylinder 7 is the second hydraulic pump 18)

[0051] (2) Two actuators with high composite frequencies separate the main pumps. (For example, the main pump for bucket cylinder 9 is the first hydraulic pump 17, and the main pump for arm cylinder 7 is the second hydraulic pump 18)

[0052] (3) Do not connect an actuator that is prone to high load pressure during compounding to the main pump side of an actuator with high flow rate frequency. (Example: Do not use the same hydraulic pump for boom lifting and swinging.)

[0053] (4) The same hydraulic pump is used for the actuators with similar load pressure bands. (Example: Boom lowering and bucket dumping use the first hydraulic pump 17)

[0054] The directional switching valve control unit 66 determines which side of the bottom side or the rod side of the cylinder is to be connected to the pump line based on the detection result of the rod operation amount, and outputs a command signal to the electromagnetic proportional valve for the directional switching valve.

[0055] The pump confluence valve control unit 67 calculates the actuator target flow rate and the pump 1 confluence valve target flow rate and the pump 2 confluence valve target flow rate as details thereof based on the actuator required flow rate, the priority pump data, and the pump dischargeable flow rate, and outputs a command signal to the confluence valve electromagnetic proportional valve so as to open in accordance with the target flow rate.

[0056] When a surplus pump flow rate is generated with respect to the actuator target flow rate, the relief valve control unit 68 outputs a command signal to the relief valve electromagnetic proportional valve to discharge the fluid.

[0057] Next, the control during actual operation will be described.

[0058] When the operating lever 21 is operated in the boom operating direction, the required flow rate calculation unit 61 calculates a boom required flow rate (actuator required flow rate) and outputs the boom required flow rate to the valve control unit 60 .

[0059] The pump discharge flow rate calculation unit 63 calculates the pump discharge flow rate of the first hydraulic pump 17 based on the value of the pump pressure sensor 49 and calculates the pump discharge flow rate of the second hydraulic pump 18 based on the value of the pump pressure sensor 50 , and outputs these pump discharge flow rates to the valve control unit 60 .

[0060] The pump confluence valve control unit 67 calculates a target flow rate of the actuator using the following method.

[0061] (1) The total value of the actuator required flow rate to which the operation command signal is input is calculated.

[0062] (2) The total value of the pump dischargeable flow rate of the first hydraulic pump 17 and the pump dischargeable flow rate of the second hydraulic pump 18 is calculated.

[0063] (3) The total value of the flow rate that can be discharged by the pump is divided by the total value of the flow rate required by the actuator to calculate the flow rate reduction ratio.

[0064] (4) The actuator target flow rate is calculated by multiplying the actuator required flow rate by the flow rate reduction ratio.

[0065] Next, the pump merging valve control unit 67 calls the record of the boom main pump from the priority pump record unit 64. Since the recorded main pump of the boom cylinder 5 is the first hydraulic pump 17, the pump merging valve control unit 67 first distributes the boom target flow rate to the boom pump 1 merging valve 28.

[0066] When the operating lever 21 is also operated in the arm operating direction, the pump merging valve control unit 67 calculates the target flow rate of the arm cylinder 7 by the same method as that of the boom cylinder 5 .

[0067] The pump merging valve control unit 67 calls the record of the arm main pump from the priority pump recording unit 64. Since the recorded main pump of the arm cylinder 7 is the second hydraulic pump 18, the pump merging valve control unit 67 first distributes the arm target flow rate to the merging valve 32 of the arm pump 2.

[0068] Next, the pump confluence valve control unit 67 calculates the main pump supplyable flow rates for the boom cylinder 5 and the arm cylinder 7, respectively. Here, the boom main pump supplyable flow rate is equal to the pump dischargeable flow rate of the first hydraulic pump 17, and the arm main pump supplyable flow rate is equal to the pump dischargeable flow rate of the second hydraulic pump 18. In the case of actuators with duplicate records of operating the main pumps at the same time, the main pump supplyable flow rate of each actuator is calculated by sequentially subtracting the target flow rate of the actuator with a higher priority from the pump dischargeable flow rate according to the priority order between the actuators determined in advance.

[0069] Next, changes in flow rate, pressure, and flow splitting and throttling loss with respect to the boom operation amount in the present invention will be described in comparison with the prior art.

[0070] First, the state of the prior art will be described. Figure 4It is a diagram showing changes in flow rate, pressure, and shunt throttling loss with respect to the boom operation amount in the prior art. In addition, the description is made assuming that the operation amount of the arm 6 is constant and the target flow rate of the arm cylinder 7 is also constant.

[0071] Figure 4 (a) represents the boom target flow rate, the supply flow rate of the main pump P1 (the supply flow rate of the first hydraulic pump 17), and the supply flow rate of the auxiliary pump P2 (the supply flow rate of the second hydraulic pump 18) relative to the boom operation amount. When the boom operation amount is considered in the direction of increasing the boom operation amount, the boom target flow rate is zero before reaching a certain constant operation amount. That is, no flow is supplied to the boom cylinder 5 from the first hydraulic pump 17 and the second hydraulic pump 18. When the boom operation amount reaches a certain constant operation amount (B1), the boom target flow rate increases. At this point in time, the boom target flow rate is smaller than the supplyable flow rate of the main pump, so the entire boom target flow rate can be supplied from the first hydraulic pump 17 as the main pump. Therefore, the target flow rate of the boom pump 1 confluence valve 28 becomes equal to the boom target flow rate, and the target flow rate of the boom pump 2 confluence valve 29 is set to zero. As a result, the boom pump 1 confluence valve 28 opens according to the target flow rate, and the pressure oil is supplied to the boom cylinder 5 through the boom direction switching valve 27.

[0072] Figure 4 (b) shows the target flow rate of the boom relative to the boom operation amount and the boom supply flow rate of the second hydraulic pump 18. The target flow rate of the boom is smaller than the supply flow rate of the main pump for the boom cylinder 7 (not shown), so the entire target flow rate of the boom can be supplied from the second hydraulic pump 18 as the main pump. Therefore, the target flow rate of the boom pump 2 confluence valve 32 becomes equal to the target flow rate of the boom, and the target flow rate of the boom pump 1 confluence valve 31 is set to zero. As a result, the confluence valve 32 of the boom pump 2 opens according to the target flow rate, and the pressure oil is supplied to the boom cylinder 7 through the boom direction switching valve 30.

[0073] Figure 4 (c) represents the pump 1 pressure (pressure of the first hydraulic pump 17), the pump 2 pressure (pressure of the second hydraulic pump 18), the boom pressure (pressure of the boom cylinder 5), and the arm pressure (pressure of the arm cylinder 7) relative to the boom operation amount. In this example, the boom pressure and the arm pressure are constant. In the state where the pressure oil is supplied from the first hydraulic pump 17 to the boom cylinder 5 and from the second hydraulic pump 18 to the arm cylinder 7, that is, in the non-merging state, the pump 1 pressure is approximately equal to the boom pressure, and the pump 2 pressure is approximately equal to the arm pressure.

[0074] Figure 4 (d) represents the flow splitting and throttling loss relative to the boom operation amount. In the non-merging state, no flow splitting occurs in each pump line, so the flow splitting and throttling loss is zero.

[0075] If the boom operation amount increases to the operation amount B2, the supply flow rate from the first hydraulic pump 17 becomes insufficient, so a target flow rate of the insufficient amount is set for the boom pump 2 merging valve 29. As a result, the boom pump 2 merging valve 29 opens according to the target flow rate, and the pressure oil passing through the boom pump 1 merging valve 28 is merged to supply the pressure oil to the boom cylinder 5. At this time, if Figure 4 As shown in (c), in order to supply the pressure oil to the boom cylinder 5, the pump 2 pressure is increased to be equal to the pump 1 pressure. In addition, the flow is divided to the boom cylinder 5 and the arm cylinder 7 in the second pump line 54, so the opening of the arm pump 2 converging valve 32 is reduced. As a result, Figure 4 As shown in (d), throttling loss occurs at the time point when the boom operation amount is B2.

[0076] Thus, when switching from the non-merging state to the merging state or from the merging state to the non-merging state, the pump discharge pressure may change and the opening amount of the merging valve may be changed, which may be the main reason for the actual flow rate supplied to the actuator to change. For example, when the lever operation amount is increased or decreased little by little, and the target flow rate at this time is close to the flow rate that the main pump can supply, the non-merging state and the merging state are frequently switched, which may cause action shock, discomfort in operation, instability of control, etc. caused by repeated changes in the pump discharge pressure. In addition, the operation of increasing or decreasing the lever operation amount little by little corresponds to the operation of putting sand into the bucket 8 and sieving it.

[0077] Next, use Figure 5 as well as Figure 6 A first embodiment of the present invention will be described. Figure 5 The figure shows the changes in the boom target flow rate, the supply flow rate of the main pump P1 (first hydraulic pump 17), and the supply flow rate of the auxiliary pump P2 (second hydraulic pump 18) relative to the boom operation amount. In addition, the changes in the arm flow rate, pressure, and throttling loss (not shown) are explained. Figure 4 (b), (c), and (d) are the same, the boom flow, pump 1 pressure, arm pressure, and boom pressure are constant, and the pump 2 pressure and throttling loss change with the switching between the non-merging state and the merging state.

[0078] in addition, Figure 6 : is a flowchart showing the procedure of the control process of the controller 20 . Figure 6 The processing shown is started, for example, by starting the engine, and is repeatedly executed every predetermined cycle (for example, every 1 millisecond). Figure 6 In the process (S1 to S5) of calculating the required flow rate, target flow rate, and flow rate that can be supplied by the main pump in sequence according to the actuator (Act) operation amount, as described above, detailed description is omitted and the processing after S6, which is a feature of the present invention, is described in detail below.

[0079] In S6, the pump confluence valve control unit 67 determines the on / off state of the main pump dischargeable flow correction flag. The state of the correction flag is determined in S13 and S14 described later. In addition, the initial value of the correction flag is set to off. When the correction flag is off, the main pump supplyable flow is not corrected (S8), and when the correction flag is on, the main pump supplyable flow is corrected by reducing a certain constant amount (predetermined amount) (S7 / flow adjustment control).

[0080] In S9, the pump confluence valve control unit 67 determines whether the target flow rate exceeds the flow rate that the main pump can supply. If it does not exceed, it is in a non-confluence state, that is, the pump confluence valve on the auxiliary pump side is closed (S11). If it exceeds, it is in a confluence state, that is, the pump confluence valve on the auxiliary pump side is open (S10). Here, the case of yes in S9 means Figure 5 When the boom operation amount in (a) exceeds X1.

[0081] In the case of the merging state, in S12, it is determined whether the insufficient flow of the main pump is within the range of the flow that the auxiliary pump can supply. If it is within the range, the correction flag is set to on in S13. If it is not within the range or in the non-merging state, the correction flag is set to off.

[0082] use Figure 5 A description will be given of changes in the flow rate with respect to the boom operation amount when the above-described control flow is applied. Figure 5 (a) indicates the case where the boom operation amount increases. Figure 5 (b) shows the case where the boom operation amount is reduced. Q1 is the flow rate that the main pump can supply, and Q0 is the corrected flow rate that the main pump can supply.

[0083] exist Figure 5 In (a), the boom operation amount increases from zero (the initial position of the operating lever 21), and during the period from reaching X1 (the first position of the operating lever 21), the boom target flow does not exceed the main pump supply flow Q1, so the control process S9 is judged as no, and becomes a non-merging state. If the boom operation amount exceeds X1, the boom target flow exceeds the main pump supply flow Q1 (the maximum flow of the main pump), so the control process S9 is judged as yes, and switches to the merging state. In addition, the correction flag is on, and the main pump supply flow is apparently reduced to Q0. As a result, when the boom operation amount exceeds X1, the pump 1 supply flow (the supply flow of the first hydraulic pump 17) temporarily decreases and becomes constant, and the pump 2 supply flow (the supply flow of the second hydraulic pump 18) increases according to the increase in the target flow. In addition, Figure 5 The value of Q1-Q0 (=ΔQ) in (a) is the "predetermined amount" of the present invention.

[0084] By apparently reducing the flow rate that the main pump can supply, the insufficient flow rate of the main pump is apparently increased. If the insufficient flow rate is within the range of the flow rate that the auxiliary pump can supply, the correction flag is maintained in the on state, but when the boom operation amount reaches X2, the insufficient flow rate exceeds the range of the flow rate that the auxiliary pump can supply, so the control process S12 is judged as no, and the correction flag becomes off. As a result, the flow rate that the main pump can supply returns to Q1, the supply flow of pump 1 increases, and the insufficient flow rate decreases, so the supply flow of pump 2 decreases. At this point in time, the flow rate that the auxiliary pump can supply is surplus, so if the boom operation amount is further increased, the supply flow of pump 2 increases. Therefore, even if a correction is made to reduce the flow rate that the main pump can supply, if the target flow rate is close to the limit of the total flow rate that the pump can supply, the correction is released, and the total flow that can be supplied to the boom cylinder 5 can be reliably supplied by the first hydraulic pump 17 and the second hydraulic pump 18.

[0085] Then, if Figure 5 As shown in (b), the situation where the boom operation amount is reduced is described. When the boom operation amount decreases from the maximum state (any position of the operating lever 21 exceeding X1 as the first position) to reach X2, the insufficient flow is within the range of the flow that the auxiliary pump can supply, so the correction flag is on. Even if the boom operation amount is further reduced and the boom operation amount is lower than X1 (the first position), the confluence state is maintained. When the boom operation amount becomes smaller and reaches X0 (the second position of the operating lever 21 that is closer to the initial position than the first position) and is lower than X0, the boom target flow is lower than the corrected main pump supply flow Q0, so the control process S9 is judged as no and switches to the non-confluence state. At the same time, the correction flag is switched to off.

[0086] Thus, when the boom operation amount increases, the non-merging state and the merging state are switched with the boom operation amount X1, but when it decreases, the switching is performed with the boom operation amount X0. For example, even if an operation is performed to increase or decrease the boom operation amount little by little near X1, if the boom operation amount does not return to X0, the merging state is maintained, and the switching between the non-merging state and the merging state disappears, which can prevent the action shock, the discomfort of the operation, the instability of the control, etc. caused by the repeated changes in the pump discharge pressure.

[0087] In addition, the correction amount (predetermined amount) of the flow rate that the main pump can supply is set within a range that does not exceed the flow rate that the auxiliary pump can supply. The smaller the correction amount, the higher the frequency of switching between the non-merging state and the merging state, which can reduce the shunt throttling loss. The larger the correction amount, the lower the frequency of switching between the non-merging state and the merging state, which can obtain good operability. For example, it is preferred that the correction amount is arbitrarily determined within a range of about 1 / 4 to 1 / 2 of the flow rate that the auxiliary pump can supply (the maximum flow rate that the second hydraulic pump 18 can supply).

[0088] (Variation Example)

[0089] Figure 7 : is a diagram showing the relationship between the boom operation amount and the flow rate of a modified example. Figure 7 As shown, in a modified example, the correction amount relative to the boom operation amount is made to vary rather than constant. Specifically, the supply flow of pump 1 gradually decreases from exceeding the boom operation amount X1, while the supply flow of pump 2 gradually increases. Furthermore, when the boom operation amount reaches X2, the insufficient flow becomes equal to the flow that the auxiliary pump can supply, and thereafter the correction amount gradually decreases so that the insufficient flow does not increase even if the target flow increases. As a result, both the supply flow of pump 1 and the supply flow of pump 2 increase. Thus, the change in the supply flow from each pump becomes smooth, and better operability can be obtained. In addition, of course, the change in the correction amount is within the range in which the insufficient flow of the main pump calculated as a result of the correction does not exceed the flow that the auxiliary pump can supply.

[0090] (Second Embodiment)

[0091] Next, use Figure 8 A second embodiment of the present invention will be described. Figure 8 is a flowchart showing the processing procedure of the controller of the second embodiment. Figure 8 In the process of S102 to S108, Figure 6 Since the steps are the same as S2 to S8, the detailed contents are omitted in the figure.

[0092] In the second embodiment, in S110, the target actuator (Act) determines whether the load pressure is greater than that of all other actuators (Act) to which the flow is supplied from the auxiliary pump of the target actuator. Taking the first embodiment as an example, when the boom cylinder 5 is used as the target actuator, the other actuator to which the flow is supplied from the auxiliary pump of the boom cylinder 5, i.e., the second hydraulic pump 18 (pump 2), is the boom cylinder 7, and the load pressure of the boom cylinder 5 is greater than the load pressure of the boom cylinder 7. Therefore, S110 determines yes. In this case, the processing after S111 is the same as the processing of S10→S12→S13 of the first embodiment. That is, the flow that the main pump can supply is corrected to be reduced by a constant amount (predetermined amount) (flow adjustment control).

[0093] On the other hand, when the determination in S110 is negative, that is, when the load pressure of the boom cylinder 5 is smaller than the load pressure of the arm cylinder 7, the discharge pressure of the second hydraulic pump 18 (pump 2) does not change even if the boom cylinder 5 is in the merging state. In such a case, by setting the correction flag of the main pump supplyable flow rate to off (S116), the non-merging state and the merging state can be actively switched, and the shunt throttling loss can be reduced.

[0094] (Third Embodiment)

[0095] Next, use Fig. 9 A third embodiment of the present invention will be described. Fig. 9is a flowchart showing the processing procedure of the controller of the third embodiment. Fig. 9 In the process of S202 to S208, Figure 6 Since the steps are the same as S2 to S8, the detailed contents are omitted in the figure.

[0096] In the third embodiment, when it is determined in S210 that the load pressure of the target actuator (Act) is greater than that of all other actuators (Act) to which the flow rate is supplied from the auxiliary pump of the target actuator, it is determined in S211 whether the load pressure of the target actuator (here, the boom cylinder 5) is below a certain threshold. The threshold (limit value) is a value that the pump tilt is reduced by horsepower control when the first hydraulic pump 17 (pump 1) and the second hydraulic pump 18 (pump 2) are at the same pressure. In this embodiment, it is set to 15 MPa, for example. That is, when the threshold is exceeded, the flow becomes a confluence state. If the pump 1 and the pump 2 are at the same pressure, the pump can discharge flow rate is reduced, and the supply flow rate to the actuator is reduced.

[0097] When the load pressure of the boom cylinder 5 is below the threshold, S211 is judged as yes, and the processing after S212 is the same as the first embodiment. When the load pressure exceeds the threshold, S211 is judged as no, and the boom is not in the confluence state (S212). By setting it in this way, it is possible to prevent the supply flow to the actuator from being reduced as a result of increasing the operation amount in order to increase the supply flow to the actuator, thereby preventing the supply flow from being reduced and causing discomfort in the operation.

[0098] In the present embodiment, the pump confluence valve and the directional switching valve are provided separately, but it is also possible to provide a directional switching valve in each of the plurality of pump lines (referred to as the pump confluence valve in the present invention) to control the supply flow from the pump and to confluence the pumps downstream of the directional switching valve. That is, it is also possible to configure the confluence valves 28 and 29 as directional switching valves and omit the directional switching valve 27.

[0099] In addition, in this embodiment, the case where the target flow rate changes according to the operation amount is described, but in addition to this, the present invention is also effective in the case where the target flow rate changes. For example, in automatic control, the required flow rate is calculated directly according to the required speed of the actuator instead of the operation amount, and the target flow rate is calculated based on the required flow rate. In addition, even if the required flow rate does not change, there is a case where the target flow rate changes due to a change in the total value of the flow rate that can be discharged by the pump.

[0100] In addition, in this embodiment, the case of a composite operation of multiple actuators is described, but the present invention is also effective in the case of a single operation of a single actuator. In particular, regardless of the single composite, the effect of the present invention can be obtained in the case of a half-lever operation that requires fine work.

[0101] The above-mentioned embodiments are examples for explaining the present invention, and are not intended to limit the scope of the present invention to these embodiments. A person skilled in the art can implement the present invention in various other forms without departing from the gist of the present invention.

[0102] Explanation of symbols

[0103] 1…Construction machinery (operating machinery),

[0104] 2…Upper rotating body,

[0105] 3…Lower running body,

[0106] 4… boom,

[0107] 5… Boom cylinder (first hydraulic actuator),

[0108] 6…arm,

[0109] 7…Arm cylinder (second hydraulic actuator),

[0110] 8…Bucket,

[0111] 9…Bucket cylinder,

[0112] 10…Cab,

[0113] 16…Control valve,

[0114] 17…First hydraulic pump,

[0115] 18…Second hydraulic pump,

[0116] 19…Pilot pump,

[0117] 20…Controller,

[0118] 21…Operating lever (operating part),

[0119] 24…Attachment 1 cylinder,

[0120] 25…Attachment 2 cylinders,

[0121] 26…Working oil tank,

[0122] 27…Directional switching valve for boom,

[0123] 28…Boom pump 1 confluence valve (confluence valve),

[0124] 29…Boom pump 2 confluence valve (confluence valve),

[0125] 30...Directional switching valve for bucket arm,

[0126] 31…Joint valve for arm pump 1,

[0127] 32…Joint valve for arm pump 2,

[0128] 33…Directional switching valve for attachment 1,

[0129] 34… Pump 1 confluence valve for attachment 1,

[0130] 35… Pump 2 confluence valve for attachment 1,

[0131] 36…Directional switching valve for attachment 2,

[0132] 37… Pump 1 confluence valve for attachment 2,

[0133] 38… Pump 2 confluence valve for attachment 2,

[0134] 39…Pump 1 discharge valve,

[0135] 40…Pump 2 discharge valve,

[0136] 41…Solenoid proportional valve for directional switching valve for boom,

[0137] 42…Solenoid proportional valve for boom pump 1 confluence valve,

[0138] 43…Solenoid proportional valve for pump 2 confluence valve for boom,

[0139] 44A... Boom bar pressure sensor,

[0140] 44B…Boom bottom pressure sensor,

[0141] 45A...arm pressure sensor,

[0142] 45B...arm bottom pressure sensor,

[0143] 46A…Attachment 1 Rod pressure sensor,

[0144] 46B…Attachment 1 bottom pressure sensor,

[0145] 47A…Attachment 2 Rod Pressure Sensor,

[0146] 47B…Attachment 2 bottom pressure sensor,

[0147] 48…Mode selector dial,

[0148] 49…First pump pressure sensor,

[0149] 50…Second pump pressure sensor,

[0150] 52…Engine,

[0151] 53…First pump line,

[0152] 54…Second pump line,

[0153] 55…Pilot primary pressure pipeline,

[0154] 56…Pilot secondary pressure pipeline,

[0155] 57…Solenoid proportional valve command circuit,

[0156] 60…Valve control unit,

[0157] 61…Requires flow calculation unit,

[0158] 63… Pump can discharge flow calculation unit,

[0159] 64…Priority pump record section,

[0160] 66…Directional switching valve control unit,

[0161] 67…Pump confluence valve control unit,

[0162] 68…Relief valve control unit,

[0163] HD…Hydraulic drive unit.

Claims

1. A working machine, comprising: a hydraulic drive device, comprising a first hydraulic pump, a second hydraulic pump, a first hydraulic actuator driven by pressure oil supplied from the first hydraulic pump, and a merging valve for merging the pressure oils respectively supplied from the first hydraulic pump and the second hydraulic pump to communicate with the first hydraulic actuator; an operating member operated by an operator; and a controller for controlling the hydraulic drive device according to the amount of operation of the operating member, It is characterized in that the controller controls the merging valve so as to supply the pressure oil from the first hydraulic pump to the first hydraulic actuator during a period when the operating member reaches the first position from the initial position when the operating member is operated in the direction in which the operation amount increases; When the operating member exceeds the first position and is operated in the direction of increasing the operating amount, the controller controls the merging valve to merge the pressure oil from the second hydraulic pump with the pressure oil from the first hydraulic pump, and supplies the merged pressure oil to the first hydraulic actuator according to the increase of the operating amount. When the operating member is operated in the direction of reducing the operating amount from any position exceeding the first position and reaches a second position closer to the initial position than the first position, the controller controls the merging valve to release the merging of the pressure oil from the first hydraulic pump and the pressure oil from the second hydraulic pump, and supplies the pressure oil from the first hydraulic pump to the first hydraulic actuator in accordance with the reduction of the operating amount.

2. The working machine according to claim 1, characterized in that: The first position is set to an operation position of the operation member corresponding to a maximum flow rate that can be supplied by the first hydraulic pump.

3. The working machine according to claim 2, characterized in that: The controller performs flow adjustment control to reduce the supply flow of the pressure oil from the first hydraulic pump to the first hydraulic actuator by a predetermined amount and to increase the supply flow of the pressure oil from the second hydraulic pump to the first hydraulic actuator by the predetermined amount when the pressure oil from the second hydraulic pump merges with the pressure oil from the first hydraulic pump.

4. The working machine according to claim 3, characterized in that: The predetermined amount is determined in advance within a range of a flow rate that can be supplied by the second hydraulic pump.

5. The working machine according to claim 3, characterized in that: The working machine further includes: a second hydraulic actuator driven by the pressure oil supplied from the second hydraulic pump; The controller performs the flow rate adjustment control only when the pressure of the first hydraulic actuator is higher than the pressure of the second hydraulic actuator when the pressure oil from the second hydraulic pump merges with the pressure oil from the first hydraulic pump.

6. The working machine according to claim 5, characterized in that: When the controller merges the pressure oil from the second hydraulic pump with the pressure oil from the first hydraulic pump, even if the pressure of the first hydraulic actuator is higher than the pressure of the second hydraulic actuator, and when the pressure of the first hydraulic actuator exceeds the limit value of the discharge pressure of the first hydraulic pump, the controller controls the merging valve so that the pressure oil from the second hydraulic pump does not merge with the pressure oil from the first hydraulic pump.

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