Fluid pressure circuit

Abstract

Provided is a fluid pressure circuit in which there is little change in rod speed even during regeneration. The present invention is provided with: a cylinder device (5); operating the switching valve (4); and a regeneration circuit having a regeneration flow path branched from the flow path between the cylinder device (5) and the operation switching valve (4) via the diverter valve (9), a detection device (63) for detecting discharge information is disposed between the cylinder device (5) and the diverter valve (9), and the diverter valve (9) is controlled on the basis of the discharge information detected by the detection device (63) and information obtained from the regeneration circuit.

Description

Technical Field

[0001] The present invention relates to a fluid pressure circuit, for example, to a fluid pressure circuit for controlling a rod stroke of a cylinder device according to an operation instruction. Background Art

[0002] Generally, a fluid pressure circuit that controls the rod stroke of a cylinder device according to an operation command is used in working machines, construction machines, loading and unloading vehicles, automobiles, etc. The fluid pressure circuit is required to be energy-saving and to regenerate the fluid discharged from the cylinder device to effectively utilize energy.

[0003] As such a fluid pressure circuit, for example, there is known Figure 7 The hydraulic circuit 152 shown. In the hydraulic circuit 152, when the operating rod 112a of the remote control valve 112 is operated in the extension direction A, the flow control valve 104 is switched to the extension position. The pressure oil from the hydraulic pump 102 is introduced into the bottom chamber 105-1 of the cylinder device 105. The rod 105a extends to the outside. On the other hand, in the hydraulic circuit 152, when the operating rod 112a is operated in the contraction direction B, the flow control valve 104 is switched to the contraction position. The pressure oil from the hydraulic pump 102 is introduced into the rod chamber 105-2. The rod 105a retreats to the inside of the cylinder device 105.

[0004] In addition, the oil passage 124 connecting the bottom chamber 105-1 and the flow control valve 104 is branched and connected to a branch oil passage 130. By opening the regenerative variable switching valve 109, a portion of the return oil discharged from the bottom chamber 105-1 is discharged to the container 108 via the branch oil passage 130 (Patent Document 1). The branch oil passage 130 and the hydraulic motor 110 together constitute a regeneration circuit. The regeneration circuit can drive the generator 111 connected to the hydraulic motor 110 to recover a portion of the energy of the return oil as electrical energy.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-29180 (page 6, Figure 1 ) Summary of the invention

[0008] Problems to be solved by the invention

[0009] In such a fluid pressure circuit, a variable throttle As is provided on the flow path connecting the oil path 124 and the oil path 126 of the flow control valve 104. By throttling the flow rate using the variable throttle As, the fluid pressure circuit can control the working speed of the rod 105a of the cylinder device 105 relative to the operation amount of the operating rod 112a of the remote control valve 112. In addition, a load W such as a load acting in the direction of gravity acts on the cylinder device 105. The load W varies depending on the load. The fluid pressure circuit adjusts the variable throttle As according to the load W so that the rod contraction speed does not change significantly. Thus, the fluid pressure circuit is designed to keep the discharge pressure between the cylinder device 105 and the flow control valve 104 within an appropriate range. However, the fluid pressure circuit branches off the return fluid during regeneration such as power storage and pressure storage, so the total flow path length of the fluid changes from that during non-regeneration, and the value of the pressure loss changes. Therefore, even if the operator's operation amount is the same, the working speed of the rod will be different during regeneration and non-regeneration, so the operator feels a deviation in the operating feel. Furthermore, during regeneration, the regeneration state and the non-regeneration state are switched according to the storage amount of the regeneration circuit. During this switching, especially when a relatively large load W is applied, the flow resistance of the circuit may change rapidly, and the discharge pressure between the cylinder device 105 and the flow control valve 104 may greatly deviate from the appropriate range. In such a situation, the rod of the cylinder device controlled according to the operation instruction may not be smoothly controlled.

[0010] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a fluid pressure circuit in which a change in rod speed is small even during regeneration.

[0011] Means for solving problems

[0012] In order to solve the above-mentioned problems, the fluid pressure circuit of the present invention comprises: a cylinder device; an operating switching valve; and a regeneration circuit, which has a regeneration flow path branched from the flow path between the cylinder device and the operating switching valve via a diverter valve, and a detection device for detecting ejection information is arranged between the cylinder device and the diverter valve, and the diverter valve is controlled based on the ejection information detected by the detection device and the information obtained from the regeneration circuit.

[0013] Therefore, based on the ejection information of the cylinder device detected by the detection equipment, that is, the load applied to the cylinder device, the flow rate of the return fluid discharged from the cylinder device to the regeneration circuit is controlled, thereby making the rod speed when the fluid flows to the regeneration circuit the same as the contraction speed of the rod when the fluid is not flowing, thereby preventing deviations in the operator's operating feel.

[0014] The regeneration circuit may include a storage device, and the flow dividing valve may be controlled based on a signal from a storage detection device that detects a storage state of the storage device and discharge information from the detection device.

[0015] Thus, when switching between regeneration and non-regeneration of the storage device, it is possible to perform driving while suppressing a change in the speed of the rod of the cylinder device.

[0016] A first throttle portion provided in the flow path between the cylinder device and the operation switching valve and a second throttle portion provided in the flow dividing valve may be controlled by functions having different positive and negative slopes.

[0017] Thus, the total throttling amount of the first throttling section and the second throttling section remains unchanged, so the speed of the rod can be easily controlled according to the load applied to the cylinder device. In addition, by controlling the first throttling section and the second throttling section, the synthetic opening characteristics during regeneration and non-regeneration can be made close.

[0018] The flow dividing valve may be a normally open electromagnetic proportional throttle valve of a three-port two-position type that simultaneously controls the openings of the first throttle portion and the second throttle portion.

[0019] Thus, the opening of the second throttle portion increases or decreases in proportion to the increase or decrease in the opening of the first throttle portion, so that the total throttling amount of the first throttle portion and the second throttle portion remains unchanged, and the speed of the rod can be controlled according to the load applied to the cylinder device with a simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram showing a wheel loader incorporating a fluid pressure circuit according to the first embodiment of the present invention.

[0021] Figure 2 This is a diagram showing a fluid pressure circuit according to the first embodiment.

[0022] Figure 3 : is a graph showing the relationship between the operating lever stroke and the pilot secondary pressure.

[0023] Figure 4 is a graph showing the relationship between the input current from the controller and the opening degree.

[0024] Figure 5 is a graph showing the relationship between the operating lever stroke and the opening area, Figure 5 (a) shows the regeneration time, Figure 5 (b) shows the non-regeneration period.

[0025] Figure 6 It is a diagram showing a fluid pressure circuit according to a second embodiment of the present invention.

[0026] Figure 7 It is a diagram showing a conventional fluid pressure circuit. DETAILED DESCRIPTION

[0027] Hereinafter, a mode for implementing the fluid pressure circuit of the present invention will be described based on examples.

[0028] Example 1

[0029] Reference Figures 1 to 5 The fluid pressure circuit of Example 1 will be described.

[0030] The hydraulic circuit as a fluid pressure circuit of the first embodiment is a hydraulic circuit that controls the stroke of a cylinder device according to an operation command in a working machine, a construction machine, a loading and unloading vehicle, a car, etc. It is suitable for a circuit in which the load of the load is heavier than the load of the working arm itself, for example, when assembled in Figure 1 The power train of the wheel loader 40 shown in the figure. The wheel loader 40 mainly includes a vehicle body 41, wheels 42 for traveling, an arm 43 for working, a hydraulic cylinder 44, and a bucket 45 for loading gravel and the like. The vehicle body 41 is provided with a power source device 50 such as an engine, a fluid circuit 51 for traveling, and a hydraulic circuit 52 for working that drives the hydraulic cylinder 5 as a cylinder device and the like.

[0031] like Figure 2 As shown, the hydraulic circuit 52 has a main hydraulic pump 2 as a fluid pressure actuator driven by a driving mechanism 1 such as an engine or an electric motor, a pilot hydraulic pump 3, a flow control valve 4 as an operation switching valve, a hydraulic cylinder 5 as a cylinder device, relief valves 6, 7, a container 8, an accumulator 60 as a storage device, a booster 61, a remote control valve 12, a pressure sensor 13, a controller 14, and oil circuits 15 to 28, 30. The accumulator 60 and the booster 61 constitute the regeneration circuit of the present invention.

[0032] The main hydraulic pump 2 is connected to a drive mechanism 1 such as an internal combustion engine, and is rotated by power from the drive mechanism 1 , thereby supplying pressurized oil to the downstream side through an oil passage 15 .

[0033] The pressure oil ejected from the main hydraulic pump 2 flows into the flow control valve 4 through the oil path 15. The flow control valve 4 is a 6-port 3-position type open center type switching valve. When the valve core is in the neutral position, all the pressure oil ejected from the main hydraulic pump 2 flows into the container 8 through the oil path 16.

[0034] In the main circuit having the main hydraulic pump 2, a relief valve 6 is provided to prevent damage to the oil machine in the circuit. When the rod 5a of the hydraulic cylinder 5 reaches the extension end or the contraction end or when a sudden load is applied to the hydraulic cylinder 5, the oil in the circuit becomes abnormally high pressure, the relief valve 6 opens. Thus, the relief valve 6 allows the high-pressure oil to be discharged to the tank 8 through the oil passage 17 and the oil passage 18.

[0035] The pilot hydraulic pump 3 is connected to the drive mechanism 1 similarly to the main hydraulic pump 2, and rotates by the power from the drive mechanism 1, thereby supplying pressurized oil to the downstream side through the oil passage 19. Here, part of the pressurized oil supplied to the downstream side through the oil passage 19 is supplied to the remote control valve 12 through the oil passage 20.

[0036] The remote control valve 12 is a variable pressure reducing valve for controlling the extension position or contraction position of the rod 5a, that is, the extension amount or contraction amount. The remote control valve 12 can output Figure 3 The pilot secondary pressure is proportional to the operating rod stroke of the operating rod 12a as shown. The remote control valve 12 is operated in the extension direction A or the contraction direction B of the rod 5a of the hydraulic cylinder 5 by the operating rod 12a, and the pilot secondary pressure is supplied to the signal port 4a or the signal port 4b of the flow control valve 4 via the signal oil path 21 or the signal oil path 22. In addition, the operation amount of the operating rod 12a is roughly equivalent to the stroke of the operating rod 12a, which is called the operating rod stroke.

[0037] When the operating rod 12a of the remote control valve 12 is operated in the extension direction A and the flow control valve 4 is switched to the extension position, the pressure oil from the main hydraulic pump 2 flows into the bottom chamber 5-1 of the hydraulic cylinder 5 through the oil passage 23 and the oil passage 24. The oil in the rod chamber 5-2 passes through the oil passage 25 and is further discharged to the container 8 through the oil passage 26 via the flow control valve 4. As a result, the rod 5a of the hydraulic cylinder 5 works in the extension direction.

[0038] On the other hand, when the operating rod 12a of the remote control valve 12 is operated in the contraction direction B and the flow control valve 4 is switched to the contraction 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 flows through the oil passage 24 and is further discharged to the container 8 through the oil passage 26 via the flow control valve 4. As a result, the rod 5a of the hydraulic cylinder 5 operates in the contraction direction.

[0039] like Figure 3 As shown in FIG. 1 , the remote control valve 12 outputs a pilot secondary pressure that increases in proportion to the increase in the operating rod stroke of the operating rod 12a of the remote control valve 12. The flow control valve 4 is configured such that the valve core performs a stroke approximately in proportion to the pilot secondary pressure of the remote control valve 12, and has an opening characteristic in which the opening amount increases in accordance with the valve core stroke. When the amount of pressure oil supplied to the hydraulic cylinder 5 increases in accordance with the increase in the opening amount of the flow control valve 4, the operating speed of the rod 5a of the hydraulic cylinder 5 increases. That is, the rod speed can be controlled according to the operating rod stroke of the operating rod 12a of the remote control valve 12.

[0040] And, in a Figure 2When the load W acts on the hydraulic cylinder 5 in the gravity direction as shown, the rod speed is controlled dominantly by the CT opening, which is an opening from the hydraulic cylinder 5 to the container 8 side. A variable throttle As is provided as a third throttle on the flow path connecting the oil path 24 and the oil path 26 of the flow control valve 4. By throttling the flow rate using the variable throttle As, the operating speed of the rod 5a based on the load W can be slowed down.

[0041] In the pilot circuit having the pilot hydraulic pump 3, a relief valve 7 is provided to control the maximum pressure in the circuit. The relief valve 7 is opened when the rod of the remote control valve 12 is in neutral, thereby discharging pressurized oil to the tank 8 through the oil passages 27 and 28.

[0042] A regenerative variable switching valve 9 as a flow divider valve is provided on the oil passage 24. The regenerative variable switching valve 9 is a normally open electromagnetic proportional throttle valve of a 3-port 2-position type. The regenerative variable switching valve 9 allows all the return oil from the bottom chamber 5-1 of the hydraulic cylinder 5 to pass through the neutral position such as during non-regeneration. The return oil passes through the oil passage 24 and is further discharged to the container 8 through the oil passage 26 via the flow control valve 4.

[0043] The regeneration variable switching valve 9 includes a flow path 9x connected to the oil path 24 as a function of a position during regeneration, i.e., a position after switching, and a flow path 9b branching from the oil path 24 and connected to the oil path 30. A variable throttle Ab as a first throttle is provided on the flow path 9b connected to the oil path 30. A variable throttle Ax as a second throttle is provided on the flow path 9x connected to the oil path 24.

[0044] When the regenerative variable switching valve 9 is switched from the neutral position to the position branching into the oil path 24 and the oil path 30, a part of the return oil from the bottom chamber 5-1 of the hydraulic cylinder 5 is throttled by the variable throttle Ab and flows into the oil path 30. The remaining return oil is throttled by the variable throttle Ax and further throttled by the variable throttle As of the downstream flow control valve 4 and discharged into the container 8.

[0045] In addition, a pressure sensor 13 is provided on the signal oil circuit 22. When the operating rod 12a of the remote control valve 12 is operated in the contraction direction B and the pilot secondary pressure is generated in the signal oil circuit 22, the pressure sensor 13 outputs an electric signal to the controller 14. The controller 14 can output an electric signal to the regenerative variable switching valve 9 from a pre-assembled operation circuit. When an electric signal is input from the pressure sensor 13 and the accumulation detector 62 described later detects that a pressure accumulation is required in the accumulator 60, that is, the allowable accumulation amount is not reached, the controller 14 outputs an electric signal to the regenerative variable switching valve 9. When an electric signal is input from the controller 14, the regenerative variable switching valve 9 switches to a position branched into the oil circuit 24 and the oil circuit 30. A part of the return oil flows into the accumulator 60 side.

[0046] like Figure 2 As shown, a booster 61 is arranged on the upstream side of the accumulator 60. The booster 61 is connected to the oil circuit 30. In addition, an accumulation detector 62 for detecting the accumulation state is arranged at the pipeline at the inlet of the accumulator 60. Although not described in detail here, the regenerative energy accumulated in the accumulator 60 can be provided to the hydraulic cylinder 5 and the like when necessary and can be appropriately utilized.

[0047] Furthermore, a pressure sensor 63 as a detection device is provided at the pipeline on the bottom chamber 5-1 side of the hydraulic cylinder 5. The pressure sensor 63 is connected to the controller 14. The pressure sensor 63 can send the detected discharge information on the bottom chamber 5-1 side of the hydraulic cylinder 5, in other words, the secondary side, to the controller 14. In addition, the detection device can detect not only the pressure, but also the flow rate or flow velocity, the degree of discharge, that is, the difference in discharge conditions caused by the difference in the weight of the load W.

[0048] Figure 4 1 is a graph showing the relationship between the input current from the controller 14 and the opening degree of the variable throttle portion As of the flow control valve 4. Figure 4 As shown, the opening of the variable throttle portion As increases or decreases in proportion to the input current from the controller 14. The input current increases or decreases in proportion to the amount of operation of the operating lever 12a in the contraction direction B. When the operating lever 12a is operated in the contraction direction B during non-regeneration, the controller 14 can variably control the opening of the variable throttle portion As according to the amount of operation.

[0049] As described above, when the load W acts on the hydraulic cylinder 5 in the gravity direction, the rod speed of the hydraulic cylinder 5 in the non-regeneration state is dominated by the CT opening, which is the opening from the hydraulic cylinder 5 to the tank 8 side. On the other hand, in the state where the regeneration variable switching valve 9 is switched to the regeneration position branched into the oil path 24 and the oil path 30, the throttle opening of the variable throttle Ab of the regeneration variable switching valve 9 and the throttle opening of the variable throttle Ax are also closely related to the control of the cylinder rod speed. That is, in the state after the regeneration variable switching valve 9 is switched, the rod speed is dominated by the synthetic opening characteristic based on the opening characteristic of the flow control valve 4 and the opening characteristic of the regeneration variable switching valve 9.

[0050] In addition, the accumulated pressure of the accumulator 60 is detected by the accumulation detector 62. The controller 14 monitors the information of the accumulated pressure sent from the accumulation detector 62. When the controller 14 determines that the accumulator 60 has reached the allowable accumulated pressure, it stops outputting the electric signal to the regeneration variable switching valve 9. By stopping the electric signal, the regeneration variable switching valve 9 returns to the neutral position, and the flow path connected to the oil path 30 is closed. As a result, the inflow to the accumulator 60 side is cut off, and a non-regeneration state is achieved. Then, the return oil of the cylinder is discharged to the container 8 only through the variable throttle portion As of the flow control valve 4.

[0051] As described above, in the hydraulic circuit 52 of the present embodiment, the regenerative variable switching valve 9 has a flow path 9b and a flow path 9x. The flow path 9b has a variable throttle Ab, which is connected to the oil path 30 during regeneration. The flow path 9x has a variable throttle Ax, which is connected to the oil path 24 during regeneration. The variable throttle Ax is connected in series with the variable throttle As through the oil path 24 during regeneration. During regeneration, a part of the return oil is branched to the oil path 30. The remaining return oil is limited in flow by the variable throttle Ax and the variable throttle As.

[0052] The following relational expressions hold true for the opening characteristics of the variable throttle portion Ab, the variable throttle portion Ax, and the variable throttle portion As.

[0053] First, since the variable throttle portion Ax and the variable throttle portion As are arranged in series, the following equation (1) is expressed based on the equation of the combined throttle portion Ac.

[0054] Synthetic throttling unit:

[0055] Furthermore, if the equivalent throttle portion of the regenerative variable switching valve 9 and the flow control valve 4 on the cylinder CT line is set to At, the case where the regenerative variable switching valve 9 is in the neutral position (non-regeneration) is expressed as the following formula (2).

[0056] At=As Formula (2)

[0057] When the regeneration variable switching valve 9 is switched (ie, during regeneration), it is expressed as the following formula (3).

[0058] At=Ac+Ab Formula (3)

[0059] Due to the above relationship, by setting Ax, the equivalent throttle portion At can be made equal regardless of whether the regenerative variable switching valve 9 is in the neutral position or in the position of branching into the oil path 24 and the oil path 30. That is, by setting Ax, Figure 5 As shown in (a) and (b), the opening characteristics (Ac+Ab) of the synthetic opening characteristic curve S based on the CT opening characteristics (Ac) during regeneration and the opening characteristics (Ab) on the branch side of the regeneration variable switching valve 9 and the opening characteristics (As) of the opening characteristic curve S' during non-regeneration can be always kept constant.

[0060] That is, based on equations (2) and (3), Ax is set so that the following equation (4) holds true.

[0061] As=Ac+Ab Formula (4)

[0062] Therefore, based on equation (1) and equation (4), the following equation (5) is derived.

[0063]

[0064] Thereby, the synthetic opening characteristic curve S during regeneration and the opening characteristic curve S′ during non-regeneration can be made substantially equal, and the rod 5 a can be smoothly controlled.

[0065] In the state where the return oil is branched and provided to the supercharger 61, the opening characteristic during regeneration is as follows: the variable throttle section Ax is arranged in parallel with the variable throttle section Ab, and the variable throttle section Ax is arranged in series with the variable throttle section As. That is, the opening characteristic during regeneration is in which the flow rate of the return oil through the oil circuit 24 is limited. When the regenerative variable switching valve 9 is switched from the regenerative position to the non-regenerative position, the opening characteristic during regeneration in which the variable throttle section Ax and the variable throttle section As are arranged in series is switched to the opening characteristic during non-regeneration in which the flow rate is limited by the variable throttle section As. By making the synthetic opening characteristic curve S during regeneration and the opening characteristic curve S' during non-regeneration approximately equal as described above, the difference between the opening characteristic during regeneration and the opening characteristic during non-regeneration can be reduced. Therefore, the sudden change in the rod speed of the hydraulic cylinder 5 can be suppressed, and the rod 5a can be smoothly controlled.

[0066] As described above, the controller 14 always monitors the discharge pressure value of the hydraulic cylinder 5 detected by the pressure sensor 63 during regeneration. The controller 14 compares the discharge pressure actually detected by the pressure sensor 63 with a reference value of the discharge pressure corresponding to the operation amount in the contraction direction B of the operation lever 12a, and calculates the difference information therebetween.

[0067] Furthermore, the controller 14 controls the input current to the regenerative variable switching valve 9 by adding or subtracting the difference information as a correction value when controlling the opening of the variable throttle portion Ax and the variable throttle portion Ab. For example, when the value of the discharge pressure on the secondary side detected by the pressure sensor 63 is higher than the reference value, that is, when the load W is greater than the reference value, the opening of the variable throttle portion Ab is controlled to be reduced.

[0068] In this way, when the load W is greater than the reference value, the controller 14 controls the opening of the variable throttle Ab to be reduced and the variable throttle Ax to be relatively opened. Thus, as a fluid pressure circuit, the variable throttle As is adjusted according to the load W so that the rod retraction speed of the hydraulic cylinder 5 does not change significantly relative to the operation amount of the operating rod 12a of the remote control valve 12, and the discharge pressure between the hydraulic cylinder 5 and the flow control valve 4 is maintained within an appropriate range. By controlling the opening of the variable throttle Ab and the variable throttle Ax according to the load W applied to the hydraulic cylinder 5 as described above, the discharge pressure between the hydraulic cylinder 5 and the flow control valve 4 can be maintained within an appropriate range, and the rod 5a of the hydraulic cylinder 5 controlled according to the operation instruction can be smoothly controlled.

[0069] In short, the following relationship will suffice.

[0070] The pressure loss caused by As when no fluid flows in the regeneration circuit (i.e., non-regeneration and non-pressure accumulation) = the pressure loss caused by the combined resistance of Ax and As when fluid flows in the regeneration circuit (i.e., regeneration and pressure accumulation) + the pressure loss caused by Ab when fluid flows in the regeneration circuit (i.e., regeneration and pressure accumulation) + the pressure loss of the regeneration circuit.

[0071] Furthermore, as described above, when the controller 14 determines that the accumulated amount of the accumulator 60 detected by the accumulation detector 62 has reached the permissible accumulated amount, the controller 14 returns the regenerative variable switching valve 9 to the neutral position. That is, the controller 14 switches to a non-regenerative state in which the flow path connected to the oil path 30 is closed and the inflow amount to the accumulator 60 side is cut off. Before switching to the non-regenerative state, the controller 14 sometimes controls the opening of the variable throttle Ab provided on the flow path 9b of the regenerative variable switching valve 9 to be reduced according to the difference between the accumulated pressure amount and the permissible accumulated pressure amount. This is performed when the load W is greater than the reference value and the difference between the accumulated amount of the accumulator 60 detected by the accumulation detector 62 and the permissible accumulated pressure amount is less than a predetermined value, that is, when the accumulated pressure amount is close to the permissible accumulated amount. As a result, it is possible to suppress the rapid change in the opening amount of the variable throttle Ab when switching from regeneration to non-regeneration, and smoothly control the rod 5a.

[0072] Furthermore, the controller 14 may also control the opening of the variable throttle portion Ab to open according to the difference between the accumulated pressure amount and the permissible accumulated pressure amount. This may be performed when the load W is greater than the reference value and the difference between the accumulated pressure amount detected by the accumulation detector 62 and the permissible accumulated pressure amount is greater than a predetermined value set in advance.

[0073] Furthermore, the regenerative variable switching valve 9 is a normally open electromagnetic proportional throttle valve of a 3-port 2-position type. The openings of the variable throttle Ab and the variable throttle Ax are controlled simultaneously. That is, when the opening of the variable throttle Ab is controlled to be open, the opening of the variable throttle Ax is reduced. In other words, it can be said that when the change in the throttle amount of the variable throttle Ab shows a linear function, the throttle amount of the variable throttle Ax is controlled to be inversely proportional. Thus, the speed of the rod 5a can be accurately controlled according to the load applied to the hydraulic cylinder 5 with a simple structure.

[0074] Example 2

[0075] Next, refer to Figure 6 The hydraulic circuit 72 of the second embodiment will be described. In addition, the overlapping description of the same configuration as that of the first embodiment will be omitted. That is, the relationship of the opening characteristics is also the same, so the description will be omitted.

[0076] exist Figure 6In the hydraulic circuit 72, the regenerative circuit includes a regenerative motor 10, a generator 11, and an electric storage device 73 such as a capacitor. In the hydraulic circuit 72, a part of the return oil flows into the regenerative motor 10 through the oil path 30 via the regenerative variable switching valve 9 by switching the regenerative variable switching valve 9. As a result, the regenerative motor 10 rotates, and electricity is generated by the generator 11. The electric storage device 73 includes an accumulation detector 74 that detects the amount of electric storage device 73 and can send it to the controller 14. For example, when the electric storage device 73 is a capacitor, a voltage detector or the like can be cited as the accumulation detector 74.

[0077] When the controller 14 determines that the stored electricity amount of the electricity storage device 73 has reached the allowable stored electricity amount based on the signal from the storage detector 74 , the controller 14 stops outputting the electric signal to the regenerative variable switching valve 9 .

[0078] As mentioned above, although the embodiment of the present invention is described with reference to the drawings, the specific structure is not limited to these embodiments, and the change and addition within the range which does not deviate from the summary of the present invention are also included in the present invention.

[0079] For example, in the aforementioned embodiment, the following structure is described: the controller 14 adjusts the opening of the variable throttling portion Ax based on the signal of the accumulation state detected by the accumulation detector 62 (74) and the discharge information from the pressure sensor 63, and controls the flow rate of the return oil discharged to the regeneration circuit, but is not limited to this. For example, even in the case where the regeneration circuit does not have an accumulation device and directly utilizes the regeneration energy, the opening of the variable throttling portion Ax can be adjusted based on the request information of the return oil from the regeneration circuit side and the discharge information from the pressure sensor 63.

[0080] Furthermore, the structure may be as follows: a regenerative variable switching valve having a variable throttling portion Ab and a regenerative variable switching valve having a variable throttling portion Ax are independently provided on the oil circuit 24, and these regenerative variable switching valves are connected to each other by another oil circuit, and each regenerative variable switching valve is connected to the controller 14, and each action is controlled.

[0081] Furthermore, in the above-mentioned embodiment, a structure in which a variable throttling portion Ax is arranged in series with the variable throttling portion As of the flow control valve 4 is described, but it is not limited to this. For example, it can also be configured so that when switching from the regeneration state to the non-regeneration state, the controller 14 can adjust the variable throttling portion As of the flow control valve 4 during regeneration so that the synthetic opening characteristics of the opening characteristics of the variable throttling portion As of the flow control valve 4 during regeneration and the opening characteristics of the variable throttling portion Ab are substantially the same as the opening characteristics of the variable throttling portion As during non-regeneration. As a result, the variable throttling portion Ax of the regeneration variable switching valve 9 can be omitted.

[0082] Furthermore, the regenerative variable switching valve 9 has been described as an electromagnetic proportional throttle valve having a variable throttle portion Ab and a variable throttle portion Ax, but is not limited thereto and may be, for example, a hydraulic flow control valve controlled by a pilot secondary pressure.

[0083] Furthermore, the flow control valve 4 is not limited to a structure that is operated by hydraulic pressure, and may be an electromagnetic proportional throttle valve.

[0084] Furthermore, in the above-mentioned embodiment, oil is used as an example of the fluid in the fluid pressure circuit, but of course all fluids such as water and air can be applied. Furthermore, the fluid pressure actuator for pressurizing the fluid in the container is not limited to a hydraulic pump, and can be variously modified according to the fluid used in the fluid pressure circuit, for example, it can also be a cylinder or an accumulator.

[0085] Furthermore, in the above-mentioned embodiment, the following situation is used as an example for explanation: from the regenerative state in which the return fluid is branched and provided to the supercharger 61 or the regenerative motor 10, the regenerative variable switching valve 9 is switched from the regenerative position to the non-regenerative position, but not limited to this. The hydraulic circuit of the present invention can of course also suppress the sudden change in the rod speed of the hydraulic cylinder 5 and smoothly control the rod 5a when switching the regenerative variable switching valve 9 from the non-regenerative position to the regenerative position.

[0086] Description of symbols

[0087] 1: driving mechanism; 2: main hydraulic pump; 3: pilot hydraulic pump; 4: flow control valve (operating switching valve); 5: hydraulic cylinder (cylinder device); 5a: rod; 8: container; 9: regenerative variable switching valve (diverter valve); 10: regenerative motor; 11: generator; 12: remote control valve; 12a: operating lever; 13: pressure sensor; 14: controller; 15-30: oil circuit; 33: oil circuit; 40: wheel loader; 52: hydraulic circuit; 60: accumulator (storage device); 61: supercharger; 62: storage detector; 63: pressure sensor (detection equipment); 72: hydraulic circuit; 73: power storage device (storage device); 74: storage detector.

Claims

1. A fluid pressure circuit, comprising: Cylinder device; operating a switching valve; and a regeneration circuit having a regeneration flow path branched from the flow path between the cylinder device and the operation switching valve via a flow dividing valve, A detection device for detecting discharge information is arranged between the cylinder device and the diverter valve. The diverter valve is controlled based on the ejection information detected by the detection device and the information obtained from the regeneration circuit.

2. The fluid pressure circuit according to claim 1, wherein: The regeneration circuit includes an accumulation device, and the flow dividing valve is controlled based on a signal from an accumulation detection device that detects an accumulation state of the accumulation device and discharge information from the detection device.

3. The fluid pressure circuit according to claim 1, wherein: A first throttle portion provided in a flow path between the cylinder device and the operation switching valve and a second throttle portion provided in the flow dividing valve are controlled by functions having different positive and negative slopes.

4. The fluid pressure circuit according to claim 3, wherein: The flow dividing valve is a normally open electromagnetic proportional throttle valve of a three-port two-position type that simultaneously controls the opening degrees of the first throttle portion and the second throttle portion.

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