FLUID PRESSURE CIRCUIT

Abstract

 There is provided a fluid pressure circuit in which changes in rod speed are small regardless of the state of use of pressure accumulation regenerative circuit. A fluid pressure circuit 10 includes a cylinder device 5; a drive source 2; a pressure accumulation regenerative circuit 10-2 that branches off from flow passages 24 and 29 between the cylinder device 5 and the drive source 2; a speed detection device 40 for detecting a rod speed of the cylinder device 5; and a control unit 14 that determines parameters for controlling a flow rate between the pressure accumulation regenerative circuit 10-2 and the flow passages 24 and 29 based on speed information detected by the speed detection device 40.

Description

{TECHNICAL FIELD}

[0001] The present invention relates to a fluid pressure circuit, for example, a fluid pressure circuit that controls the rod stroke of a cylinder device in response to an operation command.

{BACKGROUND ART}

[0002] Generally, a fluid pressure circuit that controls the rod stroke of a cylinder device in response to an operation command is used in work machines, construction machines, cargo handling vehicles, automobiles, and the like. In the fluid pressure circuit, energy saving is required, and the fluid pressure circuit may be configured to be able to effectively utilize the energy of a fluid discharged from the cylinder device.

[0003] In addition, as an example of such a fluid pressure circuit, referring to FIG. 6, a hydraulic circuit 100 includes a main hydraulic pump 102 that is a fluid pressure actuator driven by a drive mechanism 101 such as an engine or an electric motor; a pilot hydraulic pump 103; a flow rate adjustment valve 104 that is an operation switching valve; a hydraulic cylinder 105 that is a cylinder device; relief valves 106 and 107; a tank 108; an accumulator 160 that is an accumulation device; a pressure booster 161; a flow diverter valve 163; a regenerative flow rate adjustment valve 164; a remote control valve 112; a pressure sensor 113; and a controller 114.

[0004] In the hydraulic circuit 100, the main hydraulic pump 102, the pilot hydraulic pump 103, the flow rate adjustment valve 104, the hydraulic cylinder 105, the relief valves 106 and 107, the tank 108, the remote control valve 112, the pressure sensor 113, and the controller 114 constitute a main circuit 100-1 that operates the hydraulic cylinder 105, and the accumulator 160, the pressure booster 161, the flow diverter valve 163, and the regenerative flow rate adjustment valve 164 constitute a pressure accumulation regenerative circuit 100-2.

[0005] The pressure accumulation regenerative circuit 100-2 accumulates pressure in the accumulator 160 by using return oil discharged from a bottom chamber 105-1 when the hydraulic cylinder 105 descends. In addition, the pressure accumulation regenerative circuit 100-2 supplies pressure-accumulated oil in the accumulator 160 to the bottom chamber 105-1 when a load W connected to the hydraulic cylinder 105 is raised. In such a manner, the utilization of energy accumulated by the pressure accumulation regenerative circuit 100-2 for the operation of the hydraulic cylinder 105 may be simply referred to as "regeneration". Accordingly, when the load W is raised, the pump flow rate of the main hydraulic pump 102 can be reduced, and an energy-saving effect is obtained.

[0006] The pressure accumulation regenerative circuit 100-2 can be incorporated in advance when the hydraulic circuit 100 is newly manufactured as described in Patent Citation 1, thereby achieving an energy-saving effect, and it is also contemplated that the pressure accumulation regenerative circuit 100-2 can be additionally connected later (that is, retrofitted) to an existing device including only the main circuit 100-1.

{CITATION LIST}

{Patent Literature}

[0007] Patent Citation 1: WO 2019/198579 (Pages 7 and 8, FIG. 7)

{SUMMARY OF INVENTION}

{Technical Problem}

[0008] When the pressure accumulation regenerative circuit 100-2 is additionally connected to the existing main circuit 100-1, due to variations in the specifications and components of the main circuit 100-1 or differences between the flow rate control characteristics of the main circuit 100-1 and the flow rate control characteristics of the pressure accumulation regenerative circuit 100-2, a default rod speed curve Von0 immediately after the pressure accumulation regenerative circuit 100-2 is installed may differ from a rod speed curve Voff before the pressure accumulation regenerative circuit 100-2 is installed, and the rod speed differs between when pressure accumulation regenerative means is in use and when the pressure accumulation regenerative means is not in use, and therefore, an operator feels a discrepancy in operational feel, which is a risk.

[0009] The present invention has been made in view of such a problem, and object of the present invention is to provide a fluid pressure circuit in which changes in rod speed are small regardless of the state of use of pressure accumulation regenerative means.

{Solution to Problem}

[0010] In order to solve the foregoing problem, a fluid pressure circuit according to the present invention is a fluid pressure circuit including: a cylinder device; a drive source; a pressure accumulation regenerative circuit that branches off from flow passages between the cylinder device and the drive source; a speed detection device configured to detect a rod speed of the cylinder device; and a control unit configured to determine parameters for controlling a flow rate between the pressure accumulation regenerative circuit and the flow passages, based on speed information detected by the speed detection device. According to the feature of the present invention, when the pressure accumulation regenerative circuit is incorporated into an existing fluid pressure circuit, the parameters for controlling the flow rate between the pressure accumulation regenerative circuit and the flow passages is determined based on the rod speed information detected by the speed detection device, thereby allowing the rod speed in the existing fluid pressure circuit and the rod speed in the fluid pressure circuit in which the pressure accumulation regenerative circuit is incorporated to be brought closer to each other.

[0011] It may be preferable that a flow diverter valve controlled by the control unit is provided at an input-side branch portion for pressure accumulation between the flow passages and the pressure accumulation regenerative circuit. According to this preferable configuration, the rod speed during pressure accumulation can be adjusted by controlling the flow diverter valve.

[0012] It may be preferable that the flow diverter valve is a proportional valve. According to this preferable configuration, the flow diverter valve can be controlled with high accuracy.

[0013]  It may be preferable that a flow rate adjustment valve controlled by the control unit is provided at an output-side branch portion for regeneration between the flow passages and the pressure accumulation regenerative circuit. According to this preferable configuration, the rod speed during regeneration can be adjusted by controlling the flow rate adjustment valve.

[0014] It may be preferable that the flow rate adjustment valve is a proportional valve. According to this preferable configuration, the flow rate adjustment valve can be controlled with high accuracy.

[0015] It may be preferable that the control unit configured to determine the parameters based on speed information detected by the speed detection device when the pressure accumulation regenerative circuit is in use, and speed information detected by the speed detection device when the pressure accumulation regenerative circuit is not in use. According to this preferable configuration, the parameter can be adjusted such that the rod speed when the pressure accumulation regenerative circuit is in use and the rod speed when the pressure accumulation regenerative circuit is not in use are made closer to each other, based on a difference in the speed information between when the pressure accumulation regenerative circuit is in use and when the pressure accumulation regenerative circuit is not in use.

[0016] It may be preferable that the speed detection device includes a timer unit and position detection units provided at two locations on the cylinder device. According to this preferable configuration, the rod speed can be detected with high accuracy based on the movement time of a rod that moves between the two position detection units.

[0017] It may be preferable that the control unit is configured to variably control the flow rate generated by the drive source. According to this preferable configuration, the rod speed can be adjusted with high accuracy by controlling the flow rate between the pressure accumulation regenerative circuit and the flow passages and the flow rate generated by the drive source.

{BRIEF DESCRIPTION OF DRAWINGS}

[0018] 

FIG. 1 is a diagram illustrating a fluid pressure circuit according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating tuning during pressure accumulation in the embodiment.

FIG. 3 is a diagram illustrating changes of rod speed curve in the tuning when pressure is accumulated in the embodiment.

FIG. 4 is a flowchart illustrating tuning during regeneration in the embodiment.

FIG. 5 is a diagram illustrating changes of rod speed curve in the tuning when regeneration is performed in the embodiment.

FIG. 6 is a diagram illustrating a conventional fluid pressure circuit.

{DESCRIPTION OF EMBODIMENTS}

[0019] A mode for implementing a fluid pressure circuit according to the present invention will be described below based on an embodiment.

{Embodiment}

[0020] A fluid pressure circuit according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5.

[0021] A hydraulic circuit that is the fluid pressure circuit according to the embodiment is a hydraulic circuit that controls the stroke of a cylinder device in response to an operation command in a work machine, a construction machine, a cargo handling vehicle, an automobile, or the like.

[0022]  As illustrated in FIG. 1, a hydraulic circuit 10 is mainly composed of a main circuit 10-1 that is an existing fluid pressure circuit and a pressure accumulation regenerative circuit 10-2. In the present embodiment, a so-called retrofit mode in which the pressure accumulation regenerative circuit 10-2 is additionally connected to the existing main circuit 10-1 will be described.

[0023] First, the main circuit 10-1 will be described.

[0024] The main circuit 10-1 includes a drive mechanism 1 serving as a drive source such as an engine or an electric motor; a main hydraulic pump 2 serving as a drive source; a pilot hydraulic pump 3; a flow control valve 4 that is an operation switching valve; a hydraulic cylinder 5 that is a cylinder device; relief valves 6 and 7; a tank 8; a remote control valve 12; a pressure sensor 13; a controller 14 serving as a control unit; and oil passages 15 to 29.

[0025] The main hydraulic pump 2 is coupled to the drive mechanism 1, and is rotated by power from the drive mechanism 1, thereby supplying pressure oil to a downstream side through the oil passage 15.

[0026] The pressure oil discharged from the main hydraulic pump 2 flows into the flow control valve 4 through the oil passage 15. The flow control valve 4 is a six-port, three-position, open-center switching valve, and when a spool is in a neutral position, all of the pressure oil discharged from the main hydraulic pump 2 flows to the tank 8 through the oil passage 16.

[0027] In the main circuit including the main hydraulic pump 2, the relief valve 6 is installed to prevent hydraulic devices in the circuit from being damaged due to the oil in the circuit becoming blocked and rising to abnormally high pressure when a rod 5a of the hydraulic cylinder 5 reaches an extension end or a retraction end or when a sudden load is applied to the hydraulic cylinder 5, and the high-pressure oil is discharged into the tank 8 through the oil passages 17 and 18.

[0028] Similarly to the main hydraulic pump 2, the pilot hydraulic pump 3 is coupled to the drive mechanism 1, and is rotated by power from the drive mechanism 1, thereby supplying the pressure oil to the downstream side through the oil passage 19. Here, a portion of the pressure oil supplied to the downstream side through the oil passage 19 is supplied to the remote control valve 12 through the oil passage 20.

[0029] The remote control valve 12 is a variable pressure-reducing valve, and when an operating lever 12a is operated in an extension direction A or a retraction direction B of the rod 5a of the hydraulic cylinder 5, the remote control valve 12 supplies a pilot secondary pressure, which is proportional to the operating lever stroke of the operating lever 12a, to a signal port 4a or a signal port 4b of the flow control valve 4 through a signal oil passage 21 or a signal oil passage 22 to control the extension position or retraction position, that is, the extension amount or retraction amount of the rod 5a. Incidentally, the operation amount of the operating lever 12a is substantially equivalent to the stroke of the operating lever 12a, and is referred to as an operating lever stroke.

[0030] When the operating lever 12a of the remote control valve 12 is operated in the extension direction A, and thus the flow control valve 4 is switched to the extension position, the pressure oil from the main hydraulic pump 2 flows into a bottom chamber 5-1 of the hydraulic cylinder 5 through the oil passage 23, the oil passage 24, and the oil passage 29. The oil in a rod chamber 5-2 passes through the oil passage 25, and is discharged into the tank 8 through the flow control valve 4 and then through the oil passage 26. Accordingly, the rod 5a of the hydraulic cylinder 5 actuates in the extension direction.

[0031] Meanwhile, when the operating lever 12a of the remote control valve 12 is operated in the retraction direction B, and thus the flow control valve 4 is switched to the retraction position, the pressure oil from the main hydraulic pump 2 flows into the rod chamber 5-2 of the hydraulic cylinder 5 through the oil passage 23 and the oil passage 25. The oil in the bottom chamber 5-1 passes through the oil passage 29 and the oil passage 24, and is discharged into the tank 8 through the flow control valve 4 and then through the oil passage 26. Accordingly, the rod 5a of the hydraulic cylinder 5 actuates in the retraction direction.

[0032] The remote control valve 12 outputs the pilot secondary pressure that increases in proportion to an increase in the operating lever stroke of the operating lever 12a of the remote control valve 12. The flow control valve 4 is configured such that the spool strokes substantially in proportion to the pilot secondary pressure of the remote control valve 12, and has an opening characteristic in which the opening amount of the flow control valve 4 increases in accordance with the spool stroke. As the opening amount of the flow control valve 4 increases, the amount of the pressure oil supplied to the hydraulic cylinder 5 increases, and the actuation speed of the rod 5a of the hydraulic cylinder 5 increases. That is, the rod speed can be controlled in accordance with the operating lever stroke of the operating lever 12a of the remote control valve 12.

[0033]  Incidentally, when a load W acts on the hydraulic cylinder 5 in the direction of gravity, the rod speed is predominantly controlled by a C-T opening that is an opening from the hydraulic cylinder 5 to the tank 8 side. A variable throttle As is provided in a flow passage that connects the oil passage 24 and the oil passage 26 of the flow control valve 4, and the flow rate is restricted by the variable throttle As, thereby allowing the actuation speed of the rod 5a on which the load W acts to be slowed down.

[0034] In addition, in a pilot circuit including the pilot hydraulic pump 3, the relief valve 7 is installed to control the maximum pressure in the circuit. The pressure oil supplied to the pilot circuit is discharged into the tank 8 through the oil passage 27 and the oil passage 28 when the lever of the remote control valve 12 is in a neutral position.

[0035] A flow diverter valve 63 that is a component of the pressure accumulation regenerative circuit 10-2 to be described later is provided between the oil passage 29 and the oil passage 24 that are flow passages between the hydraulic cylinder 5 and the main hydraulic pump 2. When the flow diverter valve 63 is in a neutral position, such as during non-pressure accumulation, all of the oil in the bottom chamber 5-1 of the hydraulic cylinder 5 passes through the oil passage 29 and the oil passage 24, and is discharged into the tank 8 through the flow control valve 4 and then through the oil passage 26.

[0036] The flow diverter valve 63 is a three-port, two-position, normally open electromagnetic proportional throttle valve, and includes a flow passage 63x connected to the oil passage 24 as a function of a switched position that is a pressure accumulation position, and a flow passage 63b connected to an oil passage 30 serving as an input-side branch portion for pressure accumulation that branches off from the oil passage 29. A variable throttle Ab is provided in the flow passage 63b connected to the oil passage 30 that is a component of the pressure accumulation regenerative circuit 10-2, and a variable throttle Ax is provided in the flow passage 63x connected to the oil passage 24.

[0037] When the flow diverter valve 63 is switched from the neutral position to a position where the oil passage 29 branches to the oil passage 24 and the oil passage 30, that is, to the pressure accumulation position, a portion of the return oil from inside the bottom chamber 5-1 of the hydraulic cylinder 5 is restricted in flow rate by the variable throttle Ab provided in the flow passage 63b connected to the oil passage 30, and flows into the oil passage 30. In addition, the remaining return oil is restricted in flow rate by the variable throttle Ax provided in the flow passage 63x connected to the oil passage 24, and then is further restricted in flow rate by the variable throttle As of the flow control valve 4 located downstream, and is discharged into the tank 8.

[0038] In addition, the pressure sensor 13 is installed on the signal oil passage 22. The pressure sensor 13 outputs an electrical signal to the controller 14 when the operating lever 12a of the remote control valve 12 is operated in the retraction direction B and the pilot secondary pressure is generated in the signal oil passage 22. When the electrical signal is input to the controller 14 and an accumulation detector 62 to be described later detects a situation where pressure accumulation in an accumulator 60 is required, that is, when an allowable accumulation amount is not reached, an arithmetic circuit incorporated in the controller 14 in advance outputs an electrical signal to the flow diverter valve 63. The flow diverter valve 63 is switched to the pressure accumulation position upon receiving the electrical signal, thereby causing a portion of the return oil to flow into the accumulator 60 side.

[0039] Next, the pressure accumulation regenerative circuit 10-2 will be described.

[0040]  The pressure accumulation regenerative circuit 10-2 includes the accumulator 60 that is an accumulation device; a pressure booster 61; the accumulation detector 62; the flow diverter valve 63; a regenerative flow rate adjustment valve 64 serving as a flow rate adjustment valve; and oil passages 30 to 33.

[0041] The pressure booster 61 is disposed downstream of the flow diverter valve 63 described above, the accumulator 60 is disposed downstream of the pressure booster 61, and the regenerative flow rate adjustment valve 64 is disposed downstream of the accumulator 60.

[0042] The flow diverter valve 63 and the pressure booster 61 are connected by the oil passage 30. The pressure booster 61 and the accumulator 60 are connected by the oil passage 31. The accumulator 60 and the regenerative flow rate adjustment valve 64 are connected by the oil passage 32. The regenerative flow rate adjustment valve 64 and the oil passage 29 are connected by the oil passage 33 serving as an output-side branch portion for. In addition, the accumulation detector 62 that detects an accumulation state is disposed in the oil passage 31 on the input side of the accumulator 60.

[0043] The regenerative flow rate adjustment valve 64 is a two-port, two-position, normally closed electromagnetic proportional throttle valve, and includes a flow passage 64a that connects the oil passage 32 and the oil passage 33 in a switched position that is a regeneration position. A variable throttle 64b is provided in the flow passage 64a.

[0044] When the regenerative flow rate adjustment valve 64 is in a neutral position, communication between the oil passage 32 and the oil passage 33 is blocked. When the operating lever 12a of the remote control valve 12 is operated in the extension direction A, the regenerative flow rate adjustment valve 64 is switched to the regeneration position, thereby causing the pressure oil accumulated in the accumulator 60 to flow into the oil passage 29 through the oil passage 33 while the flow rate is adjusted by the variable throttle 64b, and to be supplied to the bottom chamber 5-1 of the hydraulic cylinder 5.

[0045] In addition, a pressure sensor 65 that is a detection device is installed in the oil passage 29 on the bottom chamber 5-1 side of the hydraulic cylinder 5. The pressure sensor 65 is connected to the controller 14, and can transmit discharge information on the bottom chamber 5-1 side of the hydraulic cylinder 5, in other words, on a secondary side, which is detected by the pressure sensor 65, to the controller 14. Incidentally, the detection device may detect not only pressure but also the extent of discharge such as flow rate or flow speed, that is, differences in discharge conditions due to differences in the weight of the load W.

[0046] In addition, when the pressure accumulation regenerative circuit 10-2 is additionally connected to the existing main circuit 10-1, speed detection device 40 serving as a speed detection unit is provided in the hydraulic cylinder 5.

[0047] The speed detection device 40 includes position detection units 41 and 42 provided at two upper and lower locations on the cylinder tube of the hydraulic cylinder 5 so as to be spaced apart from each other, and a timer unit 43 that measures time. The speed detection device 40 can detect a rod speed curve by detecting the movement time of the rod 5a that moves between the position detection units 41 and 42 that are spaced a predetermined distance apart (see FIG. 3).

[0048] When the hydraulic circuit 10 is configured by additionally connecting the pressure accumulation regenerative circuit 10-2 to the existing main circuit 10-1, a difference may occur in rod speed between before and after the pressure accumulation regenerative circuit 10-2 is installed. In the present embodiment, after the pressure accumulation regenerative circuit 10-2 is additionally connected to the existing main circuit 10-1, automatic tuning of the rod speed is performed.

[0049] Next, automatic tuning of the rod speed will be described with reference to FIGS. 2 to 5.

[0050] For example, after the pressure accumulation regenerative circuit 10-2 is additionally connected to the existing main circuit 10-1, automatic tuning of the rod speed is initiated when an operator presses an automatic tuning button of a control monitor installed in a work machine or the like.

[0051] Referring to FIGS. 1 to 3, the controller 14 first initiates automatic tuning of the rod speed during pressure accumulation. In the automatic tuning of the rod speed during pressure accumulation, first, with the pressure accumulation regenerative circuit 10-2 in an OFF state, that is, with the flow diverter valve 63 in the neutral position, the rod 5a is retracted, a rod speed curve Voff of the rod 5a is measured by the speed detection device 40, and the rod speed curve Voff is stored in a storage device of the controller 14 (St-1). The rod speed curve Voff is set as the target speed curve Voff (see the solid line in FIG. 3). Incidentally, the storage device may be installed in the controller 14, may be externally connected to the controller 14 via a wired or wireless connection, or may be a cloud server connected to the external controller 14 via a wired or wireless connection, and may be changed as appropriate as long as the storage device can store target information.

[0052] Next, the pressure accumulation regenerative circuit 10-2 is switched to an ON state, that is, the flow diverter valve 63 is switched to the pressure accumulation position (St-2). At this time, the flow diverter valve 63 is controlled by an electrical signal such as an initially set current value.

[0053] Next, with the pressure accumulation regenerative circuit 10-2 in an ON state, the rod 5a is retracted, a rod speed curve Von0 (see the dash-dot line in FIG. 3) of the rod 5a is measured by the speed detection device 40, and the rod speed curve Von0 is stored in the controller 14 (St-3).

[0054] Next, the controller 14 calculates a difference between the target speed curve Voff and the rod speed curve Von0, and determines whether the difference is equal to or less than a determination value K (St-4). Incidentally, the determination value K can be freely changed; however, it is preferable that the determination value K is, for example, a value within a range of 2% of the target speed curve Voff.

[0055] In St-4, it is determined that the difference between the target speed curve Voff and the rod speed curve Von0 is greater than the determination value K (St-4: No) (see FIG. 3), an adjusted electrical signal is sent from the controller 14 to the flow diverter valve 63 to adjust the opening degrees of the variable throttle Ab and the variable throttle Ax of the flow diverter valve 63 (St-5).

[0056] Thereafter, the process returns to St-3, and the rod speed curve Von0 is measured again and stored, and in St-4, a determination is made again on the difference between the target speed curve Voff and the rod speed curve Von0. St-3 to St-5 are repeatedly performed until it is determined that the difference between the target speed curve Voff and the rod speed curve Von0 is equal to or less than the determination value K.

[0057] In St-4, it is determined that the difference between the target speed curve Voff and the rod speed curve Von0 is equal to or less than the determination value K (St-4: Yes), the rod speed curve Von0 is set as an appropriate rod speed curve Von (see the dashed line in FIG. 3), and appropriate electrical signal information for the flow diverter valve 63, which is intended to obtain the appropriate rod speed curve Von, is set and stored in the controller 14 (St-6). The appropriate electrical signal information is a determined parameter for controlling the flow rate between the pressure accumulation regenerative circuit and the flow passages of the present invention. Incidentally, the parameter may indicate the absolute value of the electrical signal information or may be a coefficient by which a reference value of the electrical signal information is multiplied, and may be in any form.

[0058] According to this configuration, when pressure is accumulated in the accumulator 60, the controller 14 controls the flow diverter valve 63 based on the appropriate electrical signal information, thereby making the rod speed during pressure accumulation approximately the same before and after the pressure accumulation regenerative circuit 10-2 is installed. Therefore, it is possible to prevent the operational feel of the operator from being affected before and after the pressure accumulation regenerative circuit 10-2 is installed.

[0059] Incidentally, in the present embodiment, a mode in which in order to obtain the appropriate rod speed curve Von, the opening degrees of the variable throttle Ab and the variable throttle Ax of the flow diverter valve 63 are adjusted has been illustrated; however, in addition to the opening degrees of the variable throttle Ab and the variable throttle Ax, the opening degree of the variable throttle As of the flow control valve 4 may be adjusted. Accordingly, the rod speed can be adjusted more finely.

[0060]  Next, referring to FIGS. 1, 4, and 5, automatic tuning of the rod speed during regeneration is initiated. In the automatic tuning of the rod speed during regeneration, with the pressure accumulation regenerative circuit 10-2 in an OFF state, that is, with the regenerative flow rate adjustment valve 64 in the neutral position, the rod 5a is extended, a rod speed curve Voff' of the rod 5a is measured by the speed detection device 40, and the rod speed curve Voff' is stored in the controller 14 (St-1'). The rod speed curve Voff' is set as the target speed curve Voff' (see the solid line in FIG. 5).

[0061] Next, the pressure accumulation regenerative circuit 10-2 is switched to an ON state, that is, the regenerative flow rate adjustment valve 64 is switched to the regeneration position (St-2'). At this time, the regenerative flow rate adjustment valve 64 is controlled by an initially set electrical signal.

[0062] Next, with the pressure accumulation regenerative circuit 10-2 in an ON state, the rod 5a is extended, a rod speed curve Von0' (see the dash-dot line in FIG. 5) of the rod 5a is measured by the speed detection device 40, and the rod speed curve Von0' is stored in the controller 14 (St-3').

[0063]  Next, the controller 14 calculates a difference between the target speed curve Voff' and the rod speed curve Von0', and determines whether the difference is equal to or less than a determination value K1 (St-4'). Incidentally, the determination value K1 can be freely changed; however, it is preferable that the determination value K1 is, for example, a value within a range of 2% of the target speed curve Voff'.

[0064] In St-4', it is determined that the difference between the target speed curve Voff' and the rod speed curve Von0' is greater than the determination value K1 (St-4': No) (see FIG. 5), an adjusted electrical signal is sent from the controller 14 to the regenerative flow rate adjustment valve 64 to adjust the opening degree of the variable throttle 64b of the regenerative flow rate adjustment valve 64 (St-5'). In addition, an adjusted electrical signal is sent from the controller 14 to the drive mechanism 1 to change the rotation speed of the drive mechanism 1, thereby adjusting the discharge amount of the main hydraulic pump 2 (St-5').

[0065] Thereafter, the process returns to St-3', and the rod speed curve Von0' is measured again and stored, and in St-4', a determination is made again on the difference between the target speed curve Voff' and the rod speed curve Von0'. St-3' to St-5' are repeatedly performed until it is determined that the difference between the target speed curve Voff' and the rod speed curve Von0' is equal to or less than the determination value K1.

[0066] In St-4', it is determined that the difference between the target speed curve Voff' and the rod speed curve Von0' is equal to or less than the determination value K1 (St-4': Yes), the rod speed curve Von0' is set as an appropriate rod speed curve Von' (see the dashed line in FIG. 5), and appropriate electrical signal information for the regenerative flow rate adjustment valve 64, which is intended to obtain the appropriate rod speed curve Von', and appropriate electrical signal information for the drive mechanism 1 are set and stored in the controller 14 (St-6'). These pieces of appropriate electrical signal information are determined parameters for controlling the flow rate between the pressure accumulation regenerative circuit and the flow passages of the present invention.

[0067] According to this configuration, during regeneration to the hydraulic cylinder 5, the controller 14 controls the regenerative flow rate adjustment valve 64 and the drive mechanism 1 based on these pieces of appropriate electrical signal information, thereby making the rod speed during regeneration approximately the same before and after the pressure accumulation regenerative circuit 10-2 is installed. Therefore, it is possible to prevent the operational feel of the operator from being affected before and after the pressure accumulation regenerative circuit 10-2 is installed.

[0068] Incidentally, in the present embodiment, a mode in which the opening degree of the variable throttle 64b of the regenerative flow rate adjustment valve 64 and the rotation speed of the drive mechanism 1 are controlled to adjust the appropriate rod speed curve Von' has been illustrated; however, the present invention is not limited thereto, and the appropriate rod speed curve Von' may be adjusted by controlling at least one thereof.

[0069] Furthermore, as one method for adjusting the appropriate rod speed curve Von', for example, an unloading valve that can be controlled by the controller 14 may be provided, and the unloading valve may discharge a portion of the pressure oil from the main hydraulic pump 2 or a portion of the pressure oil from the accumulator 60 into the tank 8.

[0070] As described above, when the pressure accumulation regenerative circuit 10-2 is incorporated into the existing main circuit 10-1, the controller 14 can determine parameters for controlling the flow rate of the pressure oil between the pressure accumulation regenerative circuit 10-2 and the oil passages 24 and 29 such that the rod speed before the pressure accumulation regenerative circuit 10-2 is installed and the rod speed after the pressure accumulation regenerative circuit 10-2 is installed are made closer to each other, based on the rod speed curve detected by the speed detection device 40.

[0071] Specifically, the controller 14 can determine parameters for controlling the flow rate between the pressure accumulation regenerative circuit 10-2 and the oil passages 24 and 29 based on the differences between the rod speed curves Von0 and Von0' detected by the speed detection device 40 when the pressure accumulation regenerative circuit 10-2 is in use and the target speed curves Voff and Voff' detected by the speed detection device 40 when the pressure accumulation regenerative circuit 10-2 is not in use, and can adjust the parameters such that the rod speed when the pressure accumulation regenerative circuit 10-2 is in use and the rod speed when the pressure accumulation regenerative circuit 10-2 is not in use are made closer to each other. Therefore, regardless of the state of use of the pressure accumulation regenerative circuit 10-2, the occurrence of a discrepancy in the operational feel of the operator can be prevented.

[0072] In such a manner, when the pressure accumulation regenerative circuit 10-2 is incorporated into the existing main circuit 10-1, the tuning work of the rod speed can be performed in a short time and with high accuracy since the rod speed before and after the pressure accumulation regenerative circuit 10-2 is installed is automatically tuned by the controller 14.

[0073] In addition, the flow diverter valve 63 controlled by the controller 14 is provided in the oil passage 30 that branches off from the oil passages 29 and 24, and the rod speed during pressure accumulation can be adjusted by controlling the flow diverter valve 63.

[0074] In addition, the flow diverter valve 63 is an electromagnetic proportional throttle valve, and during pressure accumulation, the flow rate flowing from the bottom chamber 5-1 to the oil passage 24, that is, the flow rate flowing to the tank 8 and the flow rate flowing to the oil passage 30, that is, the flow rate flowing to the pressure accumulation regenerative circuit 10-2 can be adjusted with high accuracy by the variable throttle Ab and the variable throttle Ax. In other words, the rod speed during pressure accumulation can be finely adjusted.

[0075] In addition, the regenerative flow rate adjustment valve 64 controlled by the controller 14 is provided in the oil passage 33 that branches off from the oil passages 29 and 24, and the rod speed during regeneration can be adjusted by controlling the regenerative flow rate adjustment valve 64.

[0076]  In addition, the regenerative flow rate adjustment valve 64 is an electromagnetic proportional throttle valve, and during regeneration, the flow rate of the pressure oil regenerated from the accumulator 60 to the bottom chamber 5-1 can be adjusted with high accuracy by the variable throttle 64b. In other words, the rod speed during regeneration can be finely adjusted.

[0077] In addition, the controller 14 is configured to control the drive mechanism 1, and can finely adjust the appropriate rod speed by controlling the rotation speed of the drive mechanism 1 in addition to adjusting the opening degree of the variable throttle 64b of the regenerative flow rate adjustment valve 64. According to this configuration, by controlling the rotation speed of the drive mechanism 1 in accordance with the flow rate of the pressure oil regenerated from the accumulator 60 to the bottom chamber 5-1, the discharge amount of the main hydraulic pump 2 is reduced, thereby allowing an energy-saving effect to be obtained.

[0078] In addition, the speed detection device 40 includes the position detection units 41 and 42 provided at two upper and lower locations on the cylinder tube of the hydraulic cylinder 5 so as to be spaced apart from each other, and the timer unit 43 that measures time, and the rod speed can be detected with high accuracy by detecting the movement time of the rod 5a that moves between the position detection units 41 and 42.

[0079] In addition, since the target speed curves Voff and Voff' serving as the references for tuning change in proportion to speed determination device of the hydraulic cylinder 5, such as the operation amount of the operating lever 12a, a command signal to the drive mechanism 1, and the load W, when the target speed curves Voff and Voff' are measured, the tuning time is reduced by storing the information in advance in the controller 14.

[0080] Incidentally, after tuning is completed, during normal operation of a work machine or the like, the load W changes due to differences in the load of the hydraulic cylinder 5, and the rod speed curves Von and Von' after tuning change, which may result in a difference from the target speed curves Voff and Voff'.

[0081] In such a case, the pressure sensor 65 may detect differences in discharge conditions due to differences in the weight of the load W, that is, discharge change information Pw, and a command signal may be sent from the controller 14 to the flow diverter valve 63 or the regenerative flow rate adjustment valve 64 in accordance with the discharge change information Pw to adjust the opening degrees of the variable throttle Ab and the variable throttle Ax and the opening degree of the variable throttle 64b as appropriate, thereby performing control such that the rod speed curves Von and Von' and the target speed curves Voff and Voff' are approximately the same.

[0082] The embodiment of the present invention has been described above with reference to the drawings; however, the specific configurations are not limited to the embodiment, and modifications or additions that are made without departing from the scope of the present invention are also included in the present invention.

[0083] For example, in the above-described embodiment, a mode in which the flow diverter valve 63 and the regenerative flow rate adjustment valve 64 are spool-type proportional valves has been illustrated; however, the present invention is not limited thereto, and the valve type may be freely changed to a poppet type or the like.

[0084] In addition, in the above-described embodiment, a mode in which the main hydraulic pump 2 is a variable capacity pump and the discharge flow rate of the main hydraulic pump 2 is adjusted by controlling the rotation speed of the drive mechanism 1 has been illustrated; however, the discharge flow rate of the main hydraulic pump 2 may be adjusted by controlling a swash plate of the main hydraulic pump, or the main hydraulic pump 2 may be a fixed capacity pump. In this case, an unloading valve may be disposed downstream of the fixed capacity pump, and the flow rate to the hydraulic cylinder 5 may be adjusted by controlling the unloading valve via the controller 14.

[0085] In addition, in the above-described embodiment, a mode in which the speed detection device 40 includes the position detection units 41 and 42 and the timer unit 43 has been illustrated; however, when the movement distance of the rod during tuning is determined in advance, for example, when the rod moves between an upper extension limit and an upper retraction limit, the configuration of the position detection units 41 and 42 may be omitted, and only the movement time may be measured by the timer unit 43.

[0086] In addition, the speed detection device is not limited to the mode of the present embodiment, and can be freely changed. For example, the distance between the position detection units can be freely changed. In addition, the distance between the position detection units may be changed as appropriate. In addition, one position detection unit may be installed on the cylinder tube of the hydraulic cylinder, and the other position detection unit may be installed on the rod of the hydraulic cylinder. In addition, the speed detection device may be a laser displacement sensor, a capacitance displacement sensor, a contact displacement sensor, or the like.

[0087] In addition, in the above-described embodiment, a mode in which automatic tuning of the rod speed is performed when the pressure accumulation regenerative circuit 10-2 is additionally connected to the existing main circuit 10-1 has been described; however, in addition to the automatic tuning when additional connection is performed, the speed detection device 40 may measure the rod speed when the hydraulic circuit 10 is in use, and the parameters may be appropriately corrected.

[0088] In addition, in the above-described embodiment, oil has been described as an example of the fluid of the fluid pressure circuit; however, it goes without saying that the present invention can be applied to all fluids such as water or air. Further, the fluid pressure accumulator that pressurizes the fluid in the tank is not limited to a hydraulic pump, and can be variously changed in type depending on the fluid used in the fluid pressure circuit. For example, the fluid pressure accumulator may be an air cylinder, an accumulator, or the like.

{REFERENCE SIGNS LIST}

[0089] 

1

Drive mechanism (drive source)

2

Main hydraulic pump

4

Flow control valve

5

Hydraulic cylinder (cylinder device)

5-1

Bottom chamber

5-2

Rod chamber

5a

Rod

10

Hydraulic circuit (fluid pressure circuit)

10-1

Main circuit (existing fluid pressure circuit)

10-2

Pressure accumulation regenerative circuit

14

Controller (control unit)

24,

29 Oil passage (flow passage)

30

Oil passage (input-side branch portion for pressure accumulation)

33

Oil passage (output-side branch portion for regeneration)

40

Speed detection device

41, 42

Position detection unit

43

Timer unit

60

Accumulator

61

Pressure booster

62

Accumulation detector

63

Flow diverter valve

64

Regenerative flow rate adjustment valve

Ab

Variable throttle

As

Variable throttle

Ax

Variable throttle

W

Load

Claims

1. A fluid pressure circuit, comprising:

a cylinder device;

a drive source;

a pressure accumulation regenerative circuit that branches off from flow passages between the cylinder device and the drive source;

a speed detection device configured to detect a rod speed of the cylinder device; and

a control unit configured to determine parameters for controlling a flow rate between the pressure accumulation regenerative circuit and the flow passages, based on speed information detected by the speed detection device.

2. The fluid pressure circuit according to claim 1,
wherein a flow diverter valve controlled by the control unit is provided at an input-side branch portion for pressure accumulation between the flow passages and the pressure accumulation regenerative circuit.

3. The fluid pressure circuit according to claim 2,
wherein the flow diverter valve is a proportional valve.

4. The fluid pressure circuit according to claim 1,
wherein a flow rate adjustment valve controlled by the control unit is provided at an output-side branch portion for regeneration between the flow passages and the pressure accumulation regenerative circuit.

5. The fluid pressure circuit according to claim 4,
wherein the flow rate adjustment valve is a proportional valve.

6. The fluid pressure circuit according to claim 1,
wherein the control unit configured to determine the parameters based on speed information detected by the speed detection device when the pressure accumulation regenerative circuit is in use, and speed information detected by the speed detection device when the pressure accumulation regenerative circuit is not in use.

7. The fluid pressure circuit according to claim 1,
wherein the speed detection device includes a timer unit and position detection units provided at two locations on the cylinder device.

8. The fluid pressure circuit according to claim 1,
wherein the control unit is configured to variably control the flow rate generated by the drive source.

Drawing