Work machine

Abstract

The present invention aims to provide a machine tool in which operability at the start of operation of a hydraulic actuator is improved during micro-operation of a lever. To this end, a machine body controller controls a pump discharge flow rate to a minimum discharge flow rate before a first timing is detected, to a predetermined discharge flow rate greater than the minimum discharge flow rate after the first timing is detected and before a second timing is detected, and to a discharge flow rate corresponding to an amount of operation of a lever after the second timing is detected, based on a signal from a first timing detection device and a signal from a second timing detection device.

Description

Technical Field

[0001] This invention relates to the operability of hydraulic excavators and other operating machinery. Background Technology

[0002] Hydraulic excavators and other hydraulic excavators are types of machinery that use an engine to drive a pump, supplying hydraulic oil discharged from the pump to a hydraulic actuator. A directional control valve is installed between the pump and the hydraulic actuator to adjust the direction and flow rate of the hydraulic oil flowing into the actuator. The pump is a variable-capacity pump with controllable capacity, capable of adjusting the flow rate into the directional control valve.

[0003] In a hydraulic system with the center position fully open, the directional control valve adjusts the area of ​​the hydraulic oil from the pump to the inlet throttle opening of the hydraulic actuator and the bypass throttle opening that returns the hydraulic oil to the working oil tank.

[0004] When the hydraulic actuator is not operating, the inlet throttle opening is closed and the bypass throttle opening is open, so all the working oil discharged by the pump returns to the working oil tank. At this time, in order to reduce fuel consumption, the pump operates at its minimum capacity to reduce the discharge flow rate.

[0005] When the hydraulic actuator is actuated, the inlet throttling opening increases and the bypass throttling opening decreases depending on the magnitude of the actuation. Simultaneously, the pump adjusts its discharge flow rate according to the magnitude of the actuation. Thus, the pump supplies the required flow rate to the directional control valve, while suppressing unwanted flow and preventing pressure losses and bypass throttling flow that contribute to fuel cost deterioration.

[0006] The operator adjusts the opening area and pump discharge flow rate by manipulating the control lever to carry out land preparation or excavation operations.

[0007] In operations requiring fine manipulation, the amount of lever operation is small, thus reducing the flow rate of pressurized oil into the inlet throttling side of the hydraulic actuator (inlet throttling flow rate) and the pump discharge flow rate. However, in operations requiring further very low-speed and small-amplitude lever operation, even with the pump capacity minimized, the pump discharge flow rate can sometimes be excessive from an operability standpoint, impacting operability.

[0008] At this point, it is possible to reduce the engine speed to further reduce the pump discharge flow, but it is troublesome for the operator to adjust the engine speed according to the task. Moreover, if the engine speed is reduced, the flow supplied to all hydraulic actuators is reduced uniformly, which can sometimes reduce operability when multiple hydraulic actuators are operated simultaneously.

[0009] To address this issue, Patent Document 1 includes a flow control valve that connects the bottom and rod sides of the hydraulic cylinder (acting as a hydraulic actuator) to a working oil tank. In the micro-operation range of small-amplitude operation of the control lever, a portion of the pump discharge flow is returned to the working oil tank. This allows the inlet throttling flow to be smaller than the minimum pump discharge flow when the pump discharge flow is minimized, thus improving operability under micro-operation conditions.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent No. 3828680 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] However, in this method, it is difficult to improve the behavior of the hydraulic actuator when it starts to move from a stationary state.

[0015] In the initial action of micro-operation, the operating lever is moved slowly, thus the pump discharge flow rate increases slowly as well. When the hydraulic actuator is stationary, the thrust generated by the holding pressure of the hydraulic cylinder balances gravity. However, for the hydraulic actuator to begin operation, the thrust needs to further exceed the frictional force of the sliding part of the hydraulic cylinder. Generally, the frictional force of the sliding part is maximum when stationary (static friction), decreases sharply when movement begins, and increases again if the speed increases further. In a typical operation with a more abrupt start, the action occurs immediately in the region of lower friction. However, if the thrust is increased slowly through micro-operation, the action becomes an operation in a region where the speed of the hydraulic actuator increases and the frictional force changes rapidly. Therefore, sometimes the response of the hydraulic actuator is delayed relative to the amount of lever operation, or the speed increase becomes abrupt. As a result, deviations occur in the timing of the hydraulic actuator's start-up or the increase in speed, potentially impairing operability during micro-operation.

[0016] Therefore, the object of the present invention is to provide a work machine that can improve the operability of the hydraulic actuator when it starts to operate during micro-operation of a small amount of control lever.

[0017] Methods for solving problems

[0018] To achieve the above objectives, the working machine of the present invention includes: a variable capacity hydraulic pump; a hydraulic actuator driven by hydraulic oil supplied from the hydraulic pump; an operating lever for instructing the operation of the hydraulic actuator; and a controller for controlling the pump discharge flow rate, which is the discharge flow rate of the hydraulic pump. The working machine also includes: a first timing detection device for detecting a timing point before the hydraulic actuator begins to operate, i.e., a first timing point; and a second timing detection device for detecting a timing point after the hydraulic actuator begins to operate, i.e., a second timing point. Based on signals from the first timing detection device and the second timing detection device, the controller controls the pump discharge flow rate to a minimum discharge flow rate before detecting the first timing point, controls the pump discharge flow rate to a predetermined discharge flow rate greater than the minimum discharge flow rate after detecting the first timing point and before detecting the second timing point, and controls the pump discharge flow rate to a discharge flow rate corresponding to the operation amount of the operating lever after detecting the second timing point.

[0019] According to the present invention configured as described above, during the period from just before the hydraulic actuator begins to operate (first timing) to just after it begins to operate (second timing), the discharge flow rate of the hydraulic pump (pump discharge flow rate) is controlled to a predetermined discharge flow rate greater than the minimum discharge flow rate. Therefore, the thrust at the start of operation of the hydraulic actuator rapidly exceeds the static friction force of the sliding part of the hydraulic actuator. This suppresses deviations in the timing and speed rise of the hydraulic actuator's start-up, thus improving the operability of the hydraulic actuator at the start of operation during micro-operations involving small movements of the operating lever.

[0020] Invention Effects

[0021] According to the present invention, the operability of the hydraulic actuator can be improved when the operating lever is operated slightly during micro-operation. Attached Figure Description

[0022] Figure 1 This is a perspective view of a hydraulic excavator according to a first embodiment of the present invention.

[0023] Figure 2 This is a circuit diagram showing the main structural components of the hydraulic system mounted in the hydraulic excavator according to the first embodiment of the present invention.

[0024] Figure 3 This is a flowchart illustrating the control sequence of the hydraulic pump by the body controller according to the first embodiment of the present invention.

[0025] Figure 4 This indicates the relationship between the lever operation and the pump discharge flow rate.

[0026] Figure 5The pump discharge flow rate relative to the lever operation amount at the start of operation of the hydraulic actuator of the first embodiment of the present invention is shown by comparing it with the prior art.

[0027] Figure 6 The time variation of the lever operation amount and actuator speed when the hydraulic actuator of the first embodiment of the present invention starts to operate is shown by comparing it with the prior art.

[0028] Figure 7 This indicates the relationship between the speed of the hydraulic actuator and the frictional force generated in the sliding part of the hydraulic actuator.

[0029] Figure 8 This is a flowchart illustrating the control sequence of the hydraulic pump by the body controller according to the second embodiment of the present invention.

[0030] Figure 9 The time-varying actuator displacement and pump discharge flow rate when the hydraulic actuator of the second embodiment of the present invention starts to operate are illustrated by comparing it with the prior art.

[0031] Figure 10 This is a flowchart illustrating the control sequence of the hydraulic pump by the body controller according to the third embodiment of the present invention.

[0032] Figure 11 The time variation of the lever operation amount and the pump discharge flow rate when the hydraulic actuator of the third embodiment of the present invention starts to operate is illustrated by comparing it with the prior art. Detailed Implementation

[0033] Hereinafter, embodiments of the present invention will be described using the accompanying drawings. In this embodiment, a hydraulic excavator will be used as an example of a working machine. Furthermore, in each drawing, the same reference numerals are used to label the same parts, and repeated descriptions are omitted where appropriate.

[0034] Example 1

[0035] use Figure 1 The structure of the hydraulic excavator according to the first embodiment of the present invention will be described. Figure 1 This is a perspective view of the hydraulic excavator according to this embodiment. The description will be given from the perspective of the operator sitting in the driver's seat of the hydraulic excavator.

[0036] exist Figure 1 In this hydraulic excavator, there is a multi-jointed front unit 1 for excavation and other operations, and a body 2 on which the front unit 1 is mounted. The body 2 consists of a self-propelled lower traveling body 3 and an upper rotating body 4 rotatably mounted on the lower traveling body 3.

[0037] The front assembly 1 is mounted on the front of the upper rotating body 4 in a manner that allows it to rotate vertically. The front assembly 1 comprises, for example, a boom 5, a stick 6, and a bucket 7 as a working implement. The base end of the boom 5 is rotatably supported on the front of the upper rotating body 4. The base end of the stick 6 is rotatably mounted on the front end of the boom 5. The base end of the bucket 7 is rotatably mounted on the front end of the stick 6. The boom 5, stick 6, and bucket 7 are driven by a boom cylinder 8, a stick cylinder 9, and a bucket cylinder 10, respectively, which are hydraulic actuators.

[0038] The lower traveling body 3 has tracked traveling devices 11 on the left and right sides. The left and right traveling devices 11 are each driven by a traveling hydraulic motor 11a (only one side is shown in the figure) which is a hydraulic actuator.

[0039] The upper rotating body 4 rotates relative to the lower traveling body 3 via a rotary hydraulic motor (not shown) acting as a hydraulic actuator. The upper rotating body 4 is configured to include: a driver's cab 12, located on the front left side of a rotating frame (not shown) serving as a support structure; a counterweight 13, located at the rear end of the rotating frame; and a machine room 14, located between the driver's cab 12 and the counterweight 13. The driver's cab 12 contains a driver's seat (not shown) for the operator, and operating devices 41 and 42 (described later). Figure 2 ), Engine control dial 43 (refer to) Figure 2 The counterweight 13 is adjusted to balance the weight of the front device 1. The machine room 14 houses the engine 21 and hydraulic pump 22 (described later). Figure 2 Various equipment such as )

[0040] The boom 5, stick 6, bucket 7, and upper rotating body 4 are instructed to move via operating signals from operating devices 41 and 42. The lower traveling body 3 is instructed to move via operating signals from an operating pedal device (not shown).

[0041] Figure 2 It means Figure 1 The diagram shows the circuit diagram of the main components of the hydraulic system installed in the hydraulic excavator.

[0042] exist Figure 2 In this hydraulic system 20, there are: a hydraulic pump 22 and a pilot pump 31 driven by an engine 21 acting as a prime mover; a first hydraulic actuator 23 and a second hydraulic actuator 24 driven by hydraulic oil discharged from the hydraulic pump 22; and a center-position fully open type first directional control valve 25 and a second directional control valve 26 that control the flow (direction and flow rate) of hydraulic oil supplied from the hydraulic pump 22 to the first hydraulic actuator 23 and the second hydraulic actuator 24, respectively. Furthermore, Figure 2This is a diagram that representatively extracts and represents the circuit portion used to drive two hydraulic actuators. Figure 2 The circuit section, not shown, used to drive multiple other hydraulic actuators is also related to... Figure 2 The loop section shown is constructed in the same way.

[0043] The engine 21 is mechanically connected to the rotating shafts of the hydraulic pump 22 and the pilot pump 31. The engine 21 has a fuel injection device 21a. The rotational speed of the engine 21 is controlled by adjusting the fuel injection quantity of the injection device 21a through the engine controller 58, which will be described later.

[0044] The hydraulic pump 22 is a variable-capacity pump, equipped with a variable-capacity mechanism including a swashplate or swashplate. The hydraulic pump 22 has an adjuster 22a that adjusts the pump volume by controlling the tilting of the swashplate or swashplate of the variable-capacity mechanism. The adjuster 22a adjusts the pump volume based on command signals from the machine controller 60 (described later). The hydraulic pump 22 is connected to a first directional control valve 25 and a second directional control valve 26 via a discharge line 27.

[0045] The first hydraulic actuator 23 and the second hydraulic actuator 24 consist of the aforementioned boom cylinder 8, stick cylinder 9, bucket cylinder 10, and left and right travel hydraulic motors 13a (all refer to...). Figure 1 Any one of the components in a rotary hydraulic motor. Figure 2 The diagram illustrates a hydraulic cylinder.

[0046] On the intermediate bypass line 29 that guides the hydraulic oil discharged from the hydraulic pump 22 to the working oil tank 28, a first directional control valve 25 and a second directional control valve 26, both in a neutral, fully open position, are sequentially arranged from the hydraulic pump 22 side toward the working oil tank 28 side. The intermediate bypass line 29 extends through the neutral positions of the first directional control valve 25 and the second directional control valve 26, connecting the upstream first directional control valve 25 and the downstream second directional control valve 26 in series. One end (upstream side) of the intermediate bypass line 29 is connected to the discharge side of the hydraulic pump 22, i.e., the discharge line 27, and the other end (downstream side) is connected to the working oil tank 28. For example, the first directional control valve 25 and the second directional control valve 26 can be connected in parallel to the hydraulic pump 22 via the hydraulic oil supply line 30.

[0047] The first directional control valve 25 and the second directional control valve 26 are hydraulically pilot-operated valves, each having a valve core that moves according to the magnitude of the applied pilot pressure. Each directional control valve 25 and 26 has an inlet throttling passage 25a, 26a, a bypass throttling passage 25b, 26b, and an outlet throttling passage (not shown). The inlet throttling passages 25a and 26a of each directional control valve 25 and 26 are passages for connecting the discharge line 27 to the inlet throttling side of each hydraulic actuator 23, 24. The opening area of ​​the inlet throttling passages 25a and 26a of each directional control valve 25 and 26 is called the inlet throttling opening area. The bypass throttling passages 25b and 26b of each directional control valve 25 and 26 are passages for connecting the discharge line 27 to the intermediate bypass line 29. The opening area of ​​the bypass throttling passages 25b and 26b of each directional control valve 25 and 26 is called the bypass throttling opening area. The outlet throttling passages of the directional control valves 25 and 26 are pathways connecting the outlet throttling sides of the hydraulic actuators 23 and 24 to the working oil tank 28. The opening area of ​​the outlet throttling passages of the directional control valves 25 and 26 is called the outlet throttling opening area. In the directional control valves 25 and 26, the ratio of the three opening areas—the inlet throttling opening area, the bypass throttling opening area, and the outlet throttling opening area—changes as the valve core moves. The directional control valves 25 and 26 distribute the discharge flow rate (pump discharge flow rate) of the hydraulic pump 22 to the hydraulic actuators 23 and 24 and the working oil tank 28 by changing the ratio of these three opening areas according to the valve core stroke, thereby adjusting the drive (direction, position, speed, etc.) of the hydraulic actuators 23 and 24. That is, each hydraulic actuator 23 and 24 is driven at a speed proportional to the flow rate of the hydraulic oil passing through the inlet throttling passages 25a and 26a of the directional control valves 25 and 26. Hydraulic oil passing through the bypass throttling paths 25b and 26b of the directional control valves 25 and 26 is not supplied to the hydraulic actuators 23 and 24, but returns to the working oil tank 28.

[0048] The first directional control valve 25 and the second directional control valve 26 are operated by the first operating device 41 and the second operating device 42, respectively. The first operating device 41 and the second operating device 42, respectively, are operated by the operator to instruct the operation of the first hydraulic actuator 23 and the second hydraulic actuator 24, for example, by having operating levers 41a and 42a for operator operation. The first operating device 41 and the second operating device 42 are configured to function as pressure reducing valves that depressurize the hydraulic pressure of the pilot pump 31 to generate an operating pilot pressure corresponding to the operating amount. The operating pilot pressure generated by each operating device, corresponding to the operating amount, acts on the valve spools of each directional control valve 25 and 26, thereby producing a valve spool stroke of each directional control valve 25 and 26 corresponding to the magnitude of the operating pilot pressure.

[0049] A door lock valve 32 is installed in the oil line connecting the pilot pump 31 to the first operating device 41 and the second operating device 42. The door lock valve 32 enables or deactivates the operating levers 41a and 42a via operator operation; for example, it is a door lock lever 32a operated by the operator. When the door lock lever 32a is operated to the unlocked position, the pilot pump 31 is connected to the first operating device 41 and the second operating device 42. Thus, the first operating device 41 and the second operating device 42 can generate an operating pressure corresponding to the operation of the operating levers 41a and 42a. On the other hand, when the door lock lever 32a is operated to the locked position, the pilot pump 31 is connected to the working oil tank 28. Thus, the operating pressure generated by the first operating device 41 and the second operating device 42 becomes 0 regardless of the operation of the operating levers 41a and 42a, and the directional control valves 25 and 26 cannot operate. The switching position of the door lock lever 32a is detected by a sensor 55, which is used to detect the position of the lever 32a or the pressure of the oil circuit between the door lock valve 32 and the first operating device 41 and the second operating device 42.

[0050] When the operating levers 41a and 42a are in the neutral position, i.e., when the operating amount of the operating levers 41a and 42a is 0, the valve core stroke of the directional control valves 25 and 26 is 0 (valve core in neutral position). At this time, the bypass throttling opening area of ​​the directional control valves 25 and 26 is at its maximum (bypass throttling passages 25b and 26b are fully open), while the inlet throttling opening area is 0 (inlet throttling passages 25a and 26a are fully closed). Therefore, all the working oil discharged from the hydraulic pump 22 returns to the working oil tank 28, and the hydraulic actuators 23 and 24 corresponding to the directional control valves 25 and 26 are not driven. At this time, the machine controller 60 sends a signal to the regulator 22a to minimize the pump capacity, thus minimizing the flow rate of the hydraulic pump 22.

[0051] In the region where the operating amount of levers 41a and 42a is small, the corresponding valve spool stroke is also small. Based on the valve spool stroke (operating amount), the bypass throttling opening area decreases, while the inlet throttling opening area increases. Consequently, a portion of the hydraulic oil from the hydraulic pump 22 flows into each hydraulic actuator 23 and 24 via the inlet throttling passages 25a and 26a of the directional control valves 25 and 26, while the remaining hydraulic oil returns to the working oil tank 28 via the bypass throttling passages 25b and 26b. At this time, the machine controller 60 instructs the regulator 22a on the pump capacity corresponding to the operating amount of levers 41a and 42a, thereby increasing the flow rate of the hydraulic pump 22.

[0052] When the operating levers 41a and 42a are at their maximum operating range (fully operated), the valve spool stroke becomes maximum corresponding to the maximum operating range. At this time, the bypass throttling opening area is 0 (bypass throttling passages 25b and 26b are fully closed), while the inlet throttling opening area is at its maximum. As a result, all the hydraulic oil from the hydraulic pump 22 flows into each hydraulic actuator 23 and 24 through the inlet throttling passages 25a and 26a, while the flow rate of hydraulic oil returning to the working oil tank 28 becomes 0.

[0053] A first displacement sensor 51 and a second displacement sensor 52 are respectively provided on the first hydraulic actuator 23 and the second hydraulic actuator 24. The first displacement sensor 51 and the second displacement sensor 52 detect the displacement of the first hydraulic actuator 23 and the displacement of the second hydraulic actuator 24, respectively, and output the detection signal corresponding to the detected displacement of the first hydraulic actuator 23 and the second hydraulic actuator 24 to the machine body controller 60.

[0054] The pilot pressures generated by the first operating device 41 and the second operating device 42 are detected by the first pressure sensor 53 and the second pressure sensor 54, respectively. The first pressure sensor 53 and the second pressure sensor 54 output detection signals corresponding to the detected pilot pressures to the machine controller 60. The first pressure sensor 53 and the second pressure sensor 54 function as operation quantity detectors for detecting the operation quantities of the first operating device 41 and the second operating device 42, respectively.

[0055] A speed sensor 56 is installed in the engine 21 to detect the actual speed of the engine 21. The speed sensor 56 outputs a detection signal corresponding to the detected actual speed to the engine controller 58.

[0056] The engine controller 58 is configured to communicate with the engine block controller 60. The engine controller 58 receives the target speed of the engine 21 from the engine block controller 60, and sends the actual speed of the engine 21, input from the speed sensor 56, to the engine block controller 60. The engine controller 58 calculates a command value for the fuel injection quantity that matches the actual speed of the engine 21 detected by the speed sensor 56 with the target speed from the engine block controller 60, and outputs the calculated command value to the injection device 21a.

[0057] The engine control dial 43 is electrically connected to the machine controller 60. The engine control dial 43 indicates the set speed of the engine 21 according to the operator's operation and outputs the set speed indication signal to the machine controller 60.

[0058] The engine block controller 60 determines the target speed of the engine 21 based on the set speed from the engine control dial 43 and the operation of each operating device 41, 42, and outputs the determined target speed to the engine controller 58. That is, the engine block controller 60 controls the speed of the engine 21 via the engine controller 58. In addition, the engine block controller 60 controls the discharge flow rate (pump discharge flow rate) of the hydraulic pump 22 according to the operating status of the first hydraulic actuator 23 and the second hydraulic actuator 24.

[0059] Next, use Figure 3 The control processing of the hydraulic pump 22 by the machine body controller 60 in this embodiment will be described. Figure 3 This is a flowchart showing the control processing of the hydraulic pump 22 by the machine body controller 60.

[0060] Figure 3 The control process shown (steps from start to return) is executed repeatedly, for example, at a predetermined control cycle Δt. This control process is initiated, for example, by turning on a key switch (not shown) that instructs the hydraulic excavator to start.

[0061] First, the machine controller 60 determines whether the lever operation amount m of the operating levers 41a and 42a is less than the predetermined operation amount m1 (step S101). The predetermined operation amount m1 mentioned here is the operation amount before the hydraulic actuators 23 and 24 are about to start operating, for example, it is set to the operation amount when the inlet throttling passages 25a and 26a of the directional control valves 25 and 26 are open (when the working oil begins to flow into the hydraulic actuators 23 and 24).

[0062] If the determination in step S101 is "yes" (lever operation amount m < m1), the pump discharge flow rate is controlled to the minimum discharge flow rate q1. After executing step S102, the machine controller 60 returns to the beginning.

[0063] If the determination in step S101 is "No" (lever operation amount m ≥ m1), it is determined that before the hydraulic actuators 23 and 24 are about to start operating, the pump discharge flow rate is controlled to a predetermined discharge flow rate q2 that is greater than the minimum discharge flow rate q1 (step S103). That is, the pressure sensors 53 and 54 that detect the operation amount of the operating levers 41a and 42a constitute a first timing detection device for detecting the timing before the hydraulic actuators 23 and 24 are about to start operating, i.e., the first timing. The machine controller 60 determines the timing when the lever operation amount m is greater than or equal to the predetermined operation amount m1 as the first timing. After executing step S103, the control period Δt is added to the elapsed time t from the initial execution of step S103 (step S104), and it is determined whether the lever operation amount m is less than the predetermined operation amount m2 (step S105). The predetermined operation amount m2 mentioned here is the operation amount when the hydraulic actuators 23 and 24 start operating when the operating levers 41a and 42a are operated relatively quickly from the neutral position, and is set to a value greater than the above-mentioned operation amount m1.

[0064] If the determination in step S105 is "No" (lever operation amount m ≥ m2), it is determined that after the hydraulic actuators 23 and 24 have just started operating, the pump discharge flow rate is controlled to the flow rate q(m) corresponding to the lever operation amount m (step S106). That is, the pressure sensors 53 and 54 that detect the operation amount of the operating levers 41a and 42a constitute a second timing detection device for detecting the timing after the hydraulic actuators 23 and 24 have just started operating, i.e., the second timing. The machine controller 60 determines the timing when the lever operation amount m becomes a predetermined operation amount m2 or higher as the second timing. Here, in Figure 4 The diagram illustrates the relationship between lever operation and pump discharge flow rate. For example... Figure 4 As shown, the pump discharge flow rate becomes the minimum discharge flow rate q1 when the lever operation amount is below m1. If the lever operation amount exceeds m1, it increases smoothly according to the lever operation amount. After executing step S106, the machine controller 60 returns to the beginning.

[0065] If the determination in step S105 is "yes" (lever operation amount m < m2), it is determined whether the elapsed time t is greater than or equal to the predetermined time T1 (step S107). If the determination in step S107 is "no" (elapsed time t < T1), the machine controller 60 returns to the beginning.

[0066] If the determination in step S107 is "yes" (after time t≥T1), the process proceeds to step S106. After executing step S106, the controller 60 returns to the beginning. Thus, even if a long period of time has passed when the lever operation amount m has not reached the predetermined operation amount m2, the pump discharge flow rate decreases from the predetermined discharge flow rate q2 to the discharge flow rate q(m) corresponding to the lever operation amount m, thereby preventing the hydraulic actuators 23 and 24 from over-operating and thus deteriorating operability.

[0067] exist Figure 5 In this embodiment, the time-varying amounts of the operating levers 41a and 42a (lever operating amounts) and the discharge flow rate of the hydraulic pump 22 (pump discharge flow rate) when the hydraulic actuators 23 and 24 begin to operate are compared with existing technologies. Figure 5 In the diagram, the time at which the lever operation begins is set to time t1. Solid lines represent changes during relatively fast lever operations, while dashed lines represent changes during relatively slow lever operations.

[0068] In the prior art, during the period when the lever operation amount is less than the predetermined operation amount m1, the discharge flow rate (pump discharge flow rate) of the hydraulic pump 22 becomes the minimum discharge flow rate q1. After the lever operation amount reaches the operation amount m1 (after time t2), the pump discharge flow rate increases smoothly according to the lever operation amount.

[0069] In contrast, in this embodiment, when the lever operation reaches a predetermined operation amount m1, the pump discharge flow rate increases to a predetermined discharge flow rate q2, which is greater than the minimum discharge flow rate q1. Then, in the case of a relatively fast lever operation, at the time (time t3) when the lever operation reaches the predetermined operation amount m2, the pump discharge flow rate decreases to the flow rate corresponding to the lever operation amount. On the other hand, in the case of a relatively slow lever operation, at the time (time t4) when the elapsed time t from the time (time t2) when the pump discharge flow rate increases to q2 reaches a predetermined time T1, the pump discharge flow rate decreases to the flow rate corresponding to the lever operation amount. In this way, before the hydraulic actuators 23 and 24 are about to start operating and during the period when static friction acts on the sliding parts of the hydraulic actuators 23 and 24, the pump discharge flow rate is increased to a predetermined discharge flow rate q2 that is greater than the minimum discharge flow rate. After the hydraulic actuators 23 and 24 start operating and the effect of static friction disappears, the pump discharge flow rate is increased according to the lever operation amount in the same way as in the prior art. As a result, the starting movement of the hydraulic actuators 23 and 24 becomes smooth, and the same operability as in the prior art can be achieved.

[0070] exist Figure 6In this embodiment, the time variation of the operating amount (lever operation amount) of the operating levers 41a and 42a and the speed (actuator speed) of the hydraulic actuators 23 and 24 when they begin to move is illustrated by comparing with existing technology. In existing technology, the timing and speed increase of the hydraulic actuators 23 and 24 at the start of their movement may deviate relative to the operation of the operating levers 41a and 42a. Figure 7 Explain the reasons. Figure 7 This describes the relationship between the speed (actuator speed) of hydraulic actuators 23 and 24 and the frictional force generated in the sliding portion of hydraulic actuators 23 and 24. The frictional force in the sliding portion is maximum when stationary (static friction), decreases sharply upon starting movement, and increases slowly as the speed increases further. In normal operation, a relatively abrupt start occurs immediately in an area with low friction. However, if the thrust is slowly increased through micro-operation, the operation occurs in an area where the speed of hydraulic actuators 23 and 24 increases and the frictional force changes rapidly. Therefore, sometimes the response of hydraulic actuators 23 and 24 is delayed relative to the lever operation amount, or the speed increase becomes abrupt. As a result, the timing of the start of operation and the speed increase of hydraulic actuators 23 and 24 deviate, potentially impairing operability during micro-operation. In contrast, in this embodiment, the timing of the start of operation of hydraulic actuators 23 and 24 is fixed relative to the operation amount of operating levers 41a and 42a (lever operation amount), and the speed of hydraulic actuators 23 and 24 increases slowly according to the lever operation amount.

[0071] (Effect)

[0072] In this embodiment, in a hydraulic excavator (operating machinery) comprising a variable-capacity hydraulic pump 22, hydraulic actuators 23 and 24 driven by hydraulic oil supplied from the hydraulic pump 22, operating levers 41a and 42a for indicating the operation of the hydraulic actuators 23 and 24, and a controller 60 for controlling the discharge flow rate of the hydraulic pump 22, the hydraulic excavator further comprises: a first timing detection device 53 and 54 for detecting a first timing interval before the hydraulic actuators 23 and 24 are about to start operating; and a second timing detection device 53 and 54 for detecting the hydraulic actuators... The timing after devices 23 and 24 begin to operate is the second timing. Based on signals from the first timing detection devices 53 and 54 and the second timing detection devices 53 and 54, the controller 60 controls the pump discharge flow rate to the minimum discharge flow rate q1 before detecting the first timing. After detecting the first timing and before detecting the second timing, the controller 60 controls the pump discharge flow rate to a predetermined discharge flow rate q2 that is larger than the minimum discharge flow rate q1. After detecting the second timing, the controller 60 controls the pump discharge flow rate to the discharge flow rate corresponding to the operation amount of the operating levers 41a and 42a.

[0073] According to this embodiment configured as described above, during the period from just before the hydraulic actuators 23 and 24 begin to operate (first timing) to just after they begin to operate (second timing), the discharge flow rate (pump discharge flow rate) of the hydraulic pump 22 is controlled to be a predetermined discharge flow rate q2 that is greater than the minimum discharge flow rate q1. Therefore, the thrust of the hydraulic actuators 23 and 24 when they begin to operate quickly exceeds the static friction of the sliding parts of the hydraulic actuators 23 and 24. As a result, deviations in the timing and speed increase of the hydraulic actuators 23 and 24 when they begin to operate can be suppressed. Therefore, the operability of the hydraulic actuators 23 and 24 when they begin to operate can be improved during micro-operations such as small-scale operation of the operating levers 41a and 42a.

[0074] Furthermore, in this embodiment, the first timing detection device consists of sensors 53 and 54 that detect the amount of operation of the levers 41a and 42a. The controller 60 determines the timing when the amount of operation of the levers 41a and 42a detected by the sensors 53 and 54 is greater than or equal to a predetermined first operation amount m1 as the first timing. Thus, the timing (first timing) before the hydraulic actuators 23 and 24 are about to start operating can be detected based on the amount of operation of the levers 41a and 42a.

[0075] Furthermore, in this embodiment, the second timing detection device consists of sensors 53 and 54 that detect the amount of operation of the levers 41a and 42a. The controller 60 determines the earlier of the following timings: either the timing detected by sensors 53 and 54 when the amount of operation of the levers 41a and 42a becomes a predetermined second operation amount m2 or greater than the first operation amount m1, or the timing when the elapsed time t from the time the amount of operation of the levers 41a and 42a becomes a predetermined time T1 or greater. Thus, in both cases of relatively fast lever operation and relatively slow lever operation, the timing (second timing) after the hydraulic actuators 23 and 24 have just started to operate can be appropriately detected.

[0076] Example 2

[0077] The hydraulic excavator of the second embodiment of the present invention will be described with a focus on the differences from the first embodiment.

[0078] In the first embodiment, the controller 60 determines the timing after the hydraulic actuators 23 and 24 begin to operate (the second timing) when the lever operation amount reaches or exceeds a predetermined operation amount m2. However, it is difficult to accurately determine the timing after the hydraulic actuators 23 and 24 begin to operate (the second timing) based on the lever operation amount. Therefore, if the second timing is detected earlier than the actual start timing of the hydraulic actuators 23 and 24, the start timing of the hydraulic actuators 23 and 24 may be delayed due to insufficient pump discharge flow. Conversely, if the second timing is detected with a delay, the pump discharge flow becomes excessive, and the speed increase of the hydraulic actuators 23 and 24 may become steep. This embodiment aims to solve this problem.

[0079] Figure 8 This is a flowchart illustrating the pump control of the machine controller 60 in this embodiment. The differences from the pump control of the machine controller 60 in the first embodiment will be explained below.

[0080] Instead of step S105 in the first embodiment (refer to...) Figure 3 In this embodiment, the machine controller 60 determines whether the actuator displacement d is less than a predetermined displacement d1 (step S105A). The predetermined displacement d1 is preferably set to the minimum actuator displacement that can be considered as the start of operation of the hydraulic actuators 23 and 24. If the determination in step S105A is "yes" (actuator displacement d < d1), the process proceeds to step S107; if the determination is "no" (actuator displacement d ≥ d1), the process proceeds to step S106. That is, the displacement sensors 51 and 52 constitute a second timing detection device for detecting the timing after the hydraulic actuators 23 and 24 have just started operating, i.e., the second timing. The machine controller 60 determines the timing when the actuator displacement d becomes greater than or equal to the predetermined displacement d1 as the second timing.

[0081] Figure 9 A comparison with existing technologies is provided to illustrate the temporal changes in actuator displacement and pump discharge flow rate when hydraulic actuators 23 and 24 begin to operate in this embodiment. In the first embodiment (see...) Figure 5 In the previous embodiment, when the lever operation amount reached the predetermined value m2, the pump discharge flow rate decreased from flow rate q2 to flow rate q(m) corresponding to the lever operation amount m. However, in this embodiment, when the actuator displacement reached d1 (time t3), the pump discharge flow rate decreased from flow rate q2 to flow rate q(m) corresponding to the lever operation amount m.

[0082] (Effect)

[0083] The hydraulic excavator of this embodiment has displacement sensors 51 and 52 for measuring the displacement of hydraulic actuators 23 and 24 as a second timing detection device. The controller 60 determines the timing when the displacement d of hydraulic actuators 23 and 24 measured by displacement sensors 51 and 52 becomes a predetermined displacement d1 or higher as the second timing (the timing after hydraulic actuators 23 and 24 have just started to operate).

[0084] In this embodiment configured as described above, the same effect as in the first embodiment can be achieved. Furthermore, by detecting the start of operation of the hydraulic actuators 23 and 24 based on their displacement d, the detection accuracy of the timing (second timing) after the hydraulic actuators 23 and 24 have just begun to operate can be improved.

[0085] Example 3

[0086] The hydraulic excavator according to the third embodiment of the present invention will be described focusing on the differences from the first embodiment.

[0087] In the first embodiment, the machine controller 60 determines the timing when the lever operation amount reaches or exceeds a predetermined operation amount m1 as the timing (first timing) before the hydraulic actuators 23 and 24 are about to start operating. However, the lever operation amount at which the working oil begins to flow into the hydraulic actuators 23 and 24 varies depending on the machine. Therefore, if the first timing is detected later than the actual timing when the working oil begins to flow into the hydraulic actuators 23 and 24, the timing of the hydraulic actuators 23 and 24 starting to operate may be delayed due to insufficient pump discharge flow. This embodiment aims to solve this problem.

[0088] Figure 10 This is a flowchart illustrating the pump control of the body controller 60 in this embodiment. The following describes the differences from the pump control of the body controller 60 in the first embodiment.

[0089] Instead of step S101 in the first embodiment (refer to...) Figure 3 In this embodiment, the machine controller 60 determines whether the door lock lever 32a is in the locked position (step S101A). If the determination in step S101A is "yes" (door lock lever 32a is in the locked position), the process proceeds to step S102; if the determination is "no" (door lock lever 32a is in the unlocked position), the process proceeds to step S103. That is, the sensor 55 that detects the switching position of the door lock lever 32a constitutes a first timing detection device for detecting the timing before the hydraulic actuators 23 and 24 are about to start operating, i.e., the first timing. The machine controller 60 determines the timing when the door lock lever 32a is operated to the unlocked position as the first timing.

[0090] Figure 11A comparison with existing technologies is provided to illustrate the time-varying lever operation and pump discharge flow rate at the start of operation of hydraulic actuators 23 and 24 in this embodiment. In the first embodiment (see...) Figure 5 In the previous embodiment, at a time (time t2) when the lever operation amount becomes a predetermined operation amount m1 or more, the pump discharge flow rate increases from the minimum discharge flow rate q1 to the predetermined flow rate q2. However, in this embodiment, at a time (time t0) when the door lock lever 32a is operated to the unlock position, the pump discharge flow rate increases from the minimum discharge flow rate q1 to the predetermined flow rate q2.

[0091] (Effect)

[0092] In this embodiment, a door lock lever 32a is provided, which can switch between a locked position where the hydraulic actuators 23 and 24 cannot operate and an unlocked position where the hydraulic actuators 23 and 24 can operate. The first timing detection device is a sensor 55 that detects the locked position and the unlocked position of the door lock lever 32a. The controller 60 determines the timing of the change of the position of the door lock lever 32a from the locked position to the unlocked position detected by the sensor 55 as the first timing (the timing before the hydraulic actuators 23 and 24 are about to start operating).

[0093] In this embodiment configured as described above, the same effects as in the first embodiment can be achieved. Furthermore, by controlling the discharge flow rate (pump discharge flow rate) of the hydraulic pump 22 to a predetermined discharge flow rate q2 at the timing when the door lock lever 32a is operated to the unlocked position (the timing when the operator begins operation), the pump discharge flow rate can be reliably increased to the predetermined discharge flow rate q2 before the working oil begins to flow into the hydraulic actuators 23 and 24. This prevents a delay in the timing of the hydraulic actuators 23 and 24 starting to operate due to insufficient pump discharge flow.

[0094] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments and includes various modifications. For example, the above embodiments are detailed embodiments for the purpose of easily understanding and illustrating the present invention, and are not limited to having all the structures described. In addition, a part of the structure of another embodiment may be added to the structure of a certain embodiment, a part of the structure of a certain embodiment may be deleted, or a part of another embodiment may be replaced.

[0095] Explanation of reference numerals in the attached figures

[0096] 1. Front assembly, 2. Body, 3. Lower traveling body, 4. Upper rotating body, 5. Boom, 6. Stick, 7. Bucket, 8. Boom cylinder, 9. Stick cylinder, 10. Bucket cylinder, 11. Traveling device, 11a. Traveling hydraulic motor, 12. Cab, 13. Counterweight, 14. Machine room, 20. Hydraulic system, 21. Engine, 21a. Injection device, 22. Hydraulic pump, 22a. Regulator, 23. First hydraulic actuator, 24. Second hydraulic actuator, 25. First directional control valve, 25a. Inlet throttle path, 25b. Bypass throttle path, 26. Second directional control valve, 26a. Inlet throttle path, 26b. Bypass throttle path, 28. Working... Fuel tank, 31 pilot pump, 32 door lock valve, 32a door lock lever, 41 first operating device, 41a operating lever, 42 second operating device, 42a operating lever, 43 engine control dial, 51 first displacement sensor (second timing detection device), 52 second displacement sensor (second timing detection device), 53 first pressure sensor (first timing detection device, second timing detection device), 54 second pressure sensor (first timing detection device, second timing detection device), 55 sensor (first timing detection device), 56 speed sensor, 58 engine controller, 60 engine block controller.

Claims

1. A type of operating machinery, comprising: Variable capacity hydraulic pump; A hydraulic actuator, driven by hydraulic oil supplied from the hydraulic pump; An operating lever, used to indicate the action of the hydraulic actuator; and The controller controls the pump discharge flow rate, which is the discharge flow rate of the hydraulic pump. Its features are, The operating machinery includes: A first timing detection device is used to detect the timing just before the hydraulic actuator begins to operate, i.e., the first timing. The second timing detection device is used to detect the timing after the hydraulic actuator just begins to operate, i.e., the second timing. The first timing detection device and the second timing detection device are sensors that detect the amount of operation of the operating lever. The controller uses a timing condition where the amount of operation of the lever detected by the sensor reaches or exceeds a predetermined first operation amount as the first timing condition. The controller uses the earlier of the following timings as the second timing: a timing when the amount of operation of the lever detected by the sensor becomes a predetermined second amount greater than the first amount, and a timing when the elapsed time from when the amount of operation of the lever becomes greater than the first amount becomes a predetermined time or more. Before detecting the first timing, the controller controls the pump discharge flow rate to the minimum discharge flow rate; after detecting the first timing and before detecting the second timing, the controller controls the pump discharge flow rate to a predetermined discharge flow rate greater than the minimum discharge flow rate. After detecting the second timing, the controller controls the pump discharge flow rate to a discharge flow rate corresponding to the operation amount of the operating lever.

2. A type of operating machinery, comprising: Variable capacity hydraulic pump; A hydraulic actuator, driven by hydraulic oil supplied from the hydraulic pump; An operating lever, used to indicate the action of the hydraulic actuator; and The controller controls the pump discharge flow rate, which is the discharge flow rate of the hydraulic pump. Its features are, The operating machinery includes: The first timing detection device is used to detect the timing before the hydraulic actuator is about to start operating, i.e., the first timing. The second timing detection device is used to detect the timing after the hydraulic actuator starts to operate, i.e., the second timing. as well as The door lock lever is operable to switch between a locked position, which disables the hydraulic actuator, and an unlocked position, which enables the hydraulic actuator to operate. The first timing detection device is a sensor that detects the locked position and the unlocked position of the door lock rod. The controller uses the timing of the change in the position of the door lock lever, detected by the sensor, from the locked position to the unlocked position as the first timing. The controller detects the second timing based on a signal from the second timing detection device. Before detecting the first timing, the controller controls the pump discharge flow rate to the minimum discharge flow rate; after detecting the first timing and before detecting the second timing, the controller controls the pump discharge flow rate to a predetermined discharge flow rate greater than the minimum discharge flow rate. After detecting the second timing, the controller controls the pump discharge flow rate to a discharge flow rate corresponding to the operation amount of the operating lever.

3. A type of operating machinery, comprising: Variable capacity hydraulic pump; A hydraulic actuator, driven by hydraulic oil supplied from the hydraulic pump; An operating lever, used to indicate the action of the hydraulic actuator; and The controller controls the pump discharge flow rate, which is the discharge flow rate of the hydraulic pump. Its features are, The operating machinery includes: A first timing detection device is used to detect the timing just before the hydraulic actuator begins to operate, i.e., the first timing. The second timing detection device is used to detect the timing after the hydraulic actuator just begins to operate, i.e., the second timing. The second timing detection device is a displacement sensor that detects the displacement of the hydraulic actuator. The controller detects the first timing based on a signal from the first timing detection device. The controller uses the timing of when the displacement of the hydraulic actuator, as measured by the displacement sensor, reaches or exceeds a predetermined displacement as the second timing. Before detecting the first timing, the controller controls the pump discharge flow rate to the minimum discharge flow rate; after detecting the first timing and before detecting the second timing, the controller controls the pump discharge flow rate to a predetermined discharge flow rate greater than the minimum discharge flow rate. After detecting the second timing, the controller controls the pump discharge flow rate to a discharge flow rate corresponding to the operation amount of the operating lever.

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