JP6529028B2 - Fluid pressure circuit and working machine - Google Patents

Description

  The present invention relates to a fluid pressure circuit provided with an accumulator and a working machine equipped with the fluid pressure circuit.

  In the working machine, pressure oil discharged from the boom hydraulic cylinder is stored in the accumulator when the boom is lowered, and pressure oil relieved from the turning hydraulic motor is also stored in the accumulator when accelerating and decelerating the turning ( For example, refer to Patent Document 1).

JP, 2010-84888, A

  While the pressure oil discharged from the boom hydraulic cylinder is accumulated in the accumulator, the pressure oil discharged from the boom hydraulic cylinder can not be regenerated to the boom hydraulic cylinder, so a necessary pump flow rate can be secured. As a result, the operating speed of the boom hydraulic cylinder may be reduced. Therefore, it is desired to regenerate the pressure oil discharged from the boom hydraulic cylinder with a simpler configuration and to secure a necessary pump flow rate.

  The present invention has been made in view of such a point, and it is an object of the present invention to provide a fluid pressure circuit and a working machine capable of securing a necessary pump flow rate even when a working fluid is accumulated in an accumulator with a simpler configuration. I assume.

The invention described in claim 1 includes a plurality of hydraulic cylinders for simultaneous operation by the same operation by the operation body in the operation amount in accordance with the amount of pressure pump or we subjected fed working fluid in, it is accumulated by working fluid And a first valve for changing the communication amount between the head side of one fluid pressure cylinder of the plurality of fluid pressure cylinders and the accumulator in accordance with the operation amount of the operating body. A pressure accumulator circuit that causes the accumulator to accumulate the working fluid pushed out from the head side of one fluid pressure cylinder, and a plurality of hydraulic cylinder blocks the communication between the head sides when pressure accumulation is caused to accumulate in the accumulator A second valve communicating the head side of the other fluid pressure cylinder with the rod side of one of the fluid pressure cylinders and the other fluid pressure cylinder, A regenerating circuit for regenerating the working fluid pushed out from the head side of the other fluid pressure cylinder into one and the other fluid pressure cylinders via the second valve of A third valve is provided to change the amount of communication with the side in accordance with the amount of operation of the operating body, and a portion of the working fluid accumulated in the accumulator by the accumulator circuit through the third valve is one fluid It is a fluid pressure circuit provided with an auxiliary regeneration circuit for regeneration on the rod side of the pressure cylinder.

  The invention described in claim 2 is that the first valve in the fluid pressure circuit according to claim 1 communicates between the head side of one fluid pressure cylinder and the accumulator according to the operation amount of the operating body and the accumulator pressure. The third valve is a fluid pressure circuit that changes the amount of communication between the first valve and the rod side of one fluid pressure cylinder in accordance with the amount of operation of the operating body and the accumulator pressure.

  According to a third aspect of the present invention, there is provided a hydraulic circuit according to any one of the first to second aspects, provided to an airframe, a working device mounted on the airframe, and a plurality of hydraulic cylinders for moving the working device up and down. It is a working machine equipped with

  According to the first aspect of the present invention, the pressure accumulation circuit and the regeneration circuit are separated, and a part of the working fluid pushed out from the head side of one fluid pressure cylinder is accumulated in the accumulator by the first valve. The other part is regenerated on the rod side of one fluid pressure cylinder by the third valve of the auxiliary regeneration circuit, while at the same time the working fluid pushed out from the head side of the other fluid pressure cylinder is one and the other by the second valve. Since regeneration is performed on the rod side of the fluid pressure cylinder, the regeneration flow rate of the pump when pressure is accumulated in the accumulator can be suppressed, and the necessary pump flow rate can be easily secured with a simple configuration using the first to third valves.

  According to the second aspect of the present invention, the first valve changes the communication amount between the head side of one fluid pressure cylinder and the accumulator in accordance with the operation amount of the operating body and the accumulator pressure, and the third valve The valve changes the amount of communication between the first valve and the rod side of one fluid pressure cylinder in accordance with the operation amount of the operating body and the accumulator pressure, thereby accumulating pressure in the accumulator more appropriately. The working fluid can be effectively regenerated to the rod side of the pressure cylinder, the flow rate of the working fluid discharged from the pump to the rod side of one fluid pressure cylinder can be reduced, and the necessary pump flow can be more easily secured.

  According to the invention of claim 3, when lowering the work device of the work machine, it is possible to suppress the regeneration flow rate of the pump when the accumulator is pressure-accumulating, and it is possible to easily secure the necessary pump flow rate.

It is a circuit diagram showing the change state of one embodiment of the fluid pressure circuit concerning the present invention. It is a circuit diagram which shows the other switching state of a circuit same as the above. It is explanatory drawing which shows typically the control algorithm of the 1st valve | bulb of a circuit same as the above. It is explanatory drawing which shows typically the control algorithm of the 2nd valve | bulb of a circuit same as the above. It is explanatory drawing which shows typically the control algorithm of the 3rd valve | bulb of a circuit same as the above. It is explanatory drawing which shows typically a part of flow control algorithm of the pump of a circuit same as the above. FIG. 13 is an explanatory view schematically showing another part of the flow control algorithm of the pump of the above circuit. It is explanatory drawing which shows typically the control algorithm of the engine power assist function of a circuit same as the above. It is a perspective view which shows the working machine provided with the fluid pressure circuit same as the above.

  Hereinafter, the present invention will be described in detail based on one embodiment shown in FIGS. 1 to 9.

  As shown in FIG. 9, the hydraulic excavator HE as a working machine is formed by the lower traveling body 2 and the upper revolving body 3 on which the body 1 is provided so as to be pivotable by the pivoting motor 3m. A machine room 4 in which an engine, a pump and the like are mounted on the body 3, a cab 5 for protecting an operator, and a working device 6 are mounted.

  In the working device 6, the base end of the boom 7 pivoted in the vertical direction by the boom cylinders 7c1 and 7c2 as two fluid pressure cylinders arranged in parallel is pivotally supported on the upper swing body 3, and the tip of the boom 7 sticks A stick 8 pivoted in the front-rear direction by a cylinder 8 c is pivotally supported, and a bucket 9 pivoted by a bucket cylinder 9 c is pivotally supported at the tip of the stick 8. The two boom cylinders 7c1 and 7c2 are juxtaposed to the common boom 7 and simultaneously operate the same operation.

  FIG. 1 stores potential energy possessed by the working device 6 in the accumulator via the boom cylinder 7c1 and stores kinetic energy possessed by the upper swing body 3 in the accumulator via the swing motor 3m for use in assisting engine power An engine power assist system is shown.

  Next, the circuit configuration of this system will be described.

  The assist motor 15 is connected directly or via gears to the main pump shaft 14 of the main pumps 12 and 13 as pumps driven by the mounted engine 11 in the machine room 4, and the main pumps 12 and 13 and the assist motor 15 A swash plate capable of variably adjusting the pump / motor displacement (piston stroke) by an angle, and the swash plate angle (tilting angle) is controlled by the regulators 16, 17, 18 and the swash plate angle sensor 16φ, They are detected by 17φ and 18φ, and the regulators 16, 17 and 18 are controlled by solenoid valves. For example, the regulators 16 and 17 of the main pumps 12 and 13 can be automatically controlled by the negative flow control pressure (so-called negative control pressure) led by the negative flow control passage 19 nc and the electromagnetic type of the negative flow control valve 19 The control valves 19a and 19b can control signals other than negative control pressure.

  The main pumps 12 and 13 discharge the working oil as working fluid sucked from the tank 21 to the passages 22 and 23, and the pump discharge pressures thereof are detected by the pressure sensors 24 and 25. Among the pilot type control valves for direction control and flow control connected to the main pumps 12 and 13, one output passage 27 and one sub from the boom control valve 26, which is the main valve for controlling the boom cylinders 7c1 and 7c2. An output passage 29 drawn from the boom control valve 28 is connected by a passage 30 to a boom energy recovery valve 31 as a combined valve.

  The boom energy recovery valve 31 includes the pressure accumulation circuit A, the regeneration circuit B and the auxiliary regeneration circuit C shown in FIG. 1 and the hydraulic oil supplied pressurized from the main pumps 12 and 13 during the boom raising operation shown in FIG. Is a composite valve in which a plurality of circuit functions for switching between a circuit leading the two boom cylinders 7c1 and 7c2 to the head side are incorporated in a single block.

  A passage 32 drawn from the head end of one boom cylinder 7c1 is connected to the boom energy recovery valve 31 by a passage 34 through a drift reduction valve 33, and a passage 35 drawn from the head end of the other boom cylinder 7c2 is It is connected by the passage 37 through the drift reduction valve 36. The other output passage 38 drawn from the main boom control valve 26 is connected to the regeneration circuit B of the boom energy recovery valve 31. The rod sides of the boom cylinders 7c1 and 7c2 are connected to the boom energy recovery valve 31 by passages 39 and 40, respectively. Drift reduction valves 33 and 36 respectively control opening and closing between ports by controlling the pilot pressure in the spring chamber with a pilot valve (not shown).

  One output passage 27 drawn from the main boom control valve 26 can communicate with the other output passage 38 via the electromagnetic switching valve 42 and the check valve 43.

  Further, the discharge side of the assist motor 15 is connected to the tank 21 via the discharge passage 44. Furthermore, on the suction side of the assist motor 15, the tank passage 50 and the electromagnetic switching valve 51 are provided through the relief valve 48 and the check valve 49 from the accumulator passage 47 provided with the first accumulator 46 which is a plurality of accumulators. Then, the suction side passage 52 is connected. Connected to the accumulator passage 47 is a pressure sensor 55 that detects the pressure accumulated in the first accumulator 46. Further, the tank passage 50 is connected to the tank 21 from the tank passage 56 through the spring-loaded check valve 57 and further through the oil cooler 58 or the spring-loaded check valve 59. The first accumulator 46, the accumulator passage 47, the relief valve 48, the electromagnetic switching valve 51, and the pressure sensor 55 are incorporated in a single block to constitute an accumulator block 60.

  The boom energy recovery valve 31 is a control valve 61 as a first valve that constitutes a part of the pressure accumulation circuit A and a boom circuit switching valve as a second valve that constitutes a part of the regeneration circuit B. A control valve 62 and a regeneration control valve 63 as a third valve that constitutes a part of the auxiliary regeneration circuit C are provided. These valves 61 to 63 are controlled, for example, by controlling the supply and discharge of the pilot pressure by an electromagnetic switching valve operated by the operation of a lever which is an operation body (not shown) operated by an operator such as in the cab 5 (FIG. 9) Although a pilot operated type that switches is used, it is illustrated as an electromagnetic proportional directional control valve in the drawings for the sake of clarity of the description.

  The control valve 61 switches the communication and disconnection between the passage 68 connected to the first accumulator 46 (accumulator block 60) via the check valve 67 and the passage 34, thereby the first accumulator 46 from the boom cylinder 7c1. It is a flow control valve that allows pressure accumulation in The control valve 61 is a valve that allows hydraulic fluid to flow more than returning it from the normal cylinder (such as the boom cylinders 7c1 and 7c2) to the tank 21, and gives priority to storing pressure oil in the first accumulator 46. It has become.

  The main control valve 62 stores the boom cylinder 7c1 and the boom cylinder 7c2 by switching the relationship between the passage 71 and the passage 72, the relationship between the passage 73 and the passage 74, and the relationship between the passage 75 and the passage 76, respectively. And the self-regeneration cylinder. That is, when pressure is accumulated in the first accumulator 46 by switching the control valve 61, the main control valve 62 shuts off the communication between the head sides of the boom cylinders 7c1 and 7c2 and the head side of the boom cylinder 7c2 and the boom cylinders It is comprised so that each rod side of 7c1, 7c2 may be connected.

  In the passage 71, the passage 30 is connected via the check valve 78, the passage 72 is connected with the passage 37 and the passage 79 branched from the passage 30, the passage 73 is branched from the passage 72, the passage 74 is reversed The stop valve 80 is connected to the passage 40, the passage 75 is connected to the output passage 38 and the passage 39, and the passage 76 is branched from the passage 40.

  The regeneration control valve 63 is connected to the control valve 61, ie, the passage 82 branched from the upstream side of the check valve 67 with respect to the passage 68, and the passage 39 connected to the rod side of the boom cylinder 7c1 via the check valve 83. By switching communication with and blocking from the head side of the boom cylinder 7c1 to the first accumulator 46 through the control valve 61 to a portion (approximately half) of the hydraulic fluid to the rod side of the boom cylinder 7c1. It is a flow control valve that regenerates. The regeneration control valve 63 interlocks with the control valve 61, and when the pressure is accumulated in the first accumulator 46 by switching the control valve 61, the control valve 61 communicates with the head side of the boom cylinder 7c1, When the communication between the head side of the boom cylinder 7c1 and the first accumulator 46 is shut off by switching 61, the control valve 61 and the head side of the boom cylinder 7c1 are shut off.

  As shown in FIG. 1, the pressure accumulation circuit A is a control valve 61 in the boom energy recovery valve 31 through a drift reduction valve 33 and a passage 34 from a passage 32 drawn from the head end of one boom cylinder 7c1. , And a circuit from the passage 68 to the first accumulator 46 via the check valve 67, and causes the first accumulator 46 to accumulate a portion (approximately half) of the hydraulic oil pushed out from the head side of the boom cylinder 7c1. It has a function.

  Further, the regeneration circuit B passes from the passage 35 drawn out from the head end of the other boom cylinder 7c2 through the drift reduction valve 36 and the passage 37, and the passage 73 in the boom energy recovery valve 31, the main control valve 62, the passage 74, through the check valve 80 and the passage 40 to the rod side end of the other boom cylinder 7c2, and from the passage 35 through the drift reduction valve 36 and the passage 37, the passage 73 in the boom energy recovery valve 31, main It is a circuit leading to the rod side end of one boom cylinder 7c1 through the control valve 62, the passage 74, the check valve 80, the passage 76, the main control valve 62, the passage 75 and the passage 39 and pushed out from the head side of the boom cylinder 7c2. The hydraulic fluid has a function of regenerating the hydraulic oil on the rod side of the boom cylinders 7c1 and 7c2.

  Further, the auxiliary regeneration circuit C is branched from the pressure accumulation circuit A, and from the passage 32 drawn out from the head side end of one boom cylinder 7c1, the drift reduction valve 33 and the passage 34 in the boom energy recovery valve 31 It is a circuit from the passage 39 to the rod side end of one boom cylinder 7c1 through the control valve 61, the passage 82, the regeneration control valve 63, the check valve 83 and the passage 84 and is pushed out from the head side of the boom cylinder 7c1. It has a function of regenerating the other part of the hydraulic oil except the part accumulated in the first accumulator 46 on the rod side of the boom cylinder 7c1.

  Further, relief valves 94 and 95, which are reverse to each other, are interposed between the passages 92 and 93 of the motor drive circuit D for connecting the swing control valve 91 for controlling the swing direction and speed of the swing motor 3m and the swing motor 3m. A check valve 97, 98 is provided, and a tank passage function for returning oil discharged from the motor drive circuit D to the tank 21 between the relief valves 94, 95 and between the check valves 97, 98; The make-up passage 99 having a make-up function capable of replenishing the hydraulic oil is connected to the second accumulator 100 which supplies the pressure oil. Then, from the make-up passage 99, hydraulic oil is applied to the side having a possibility of vacuum generation in the passages 92, 93 through the check valves 97, 98 at a pressure not exceeding the spring biasing pressure of the spring check valve 57. refill.

  Further, the passages 92 and 93 of the motor drive circuit D are communicated with the passage 104 for recovering the swirl energy through the check valves 102 and 103, and the passage 104 changes the original pressure on the inlet side by the back pressure on the outlet side. It is connected to the passage 106 via the difficult sequence valve 105, which is connected to the first accumulator 46 and the passage 68.

  In the circuit configuration as described above, each swash plate angle sensor 16φ, 17φ, 18φ and pressure sensors 24, 25 and 55 input the detected swash plate angle signal and pressure signal to an on-vehicle controller (not shown), Further, each of the valves 42 and 51 is switched by on / off operation or proportional operation according to the drive signal by a drive signal output from an onboard controller (not shown). The boom control valves 26, 28, the swing control valve 91, and other hydraulic actuator control valves (not shown) (for travel motor, stick cylinder, bucket cylinder, etc.) are located in the cab 5 (FIG. 9) or the like. A pilot operation is performed by a manual operation valve so-called remote control valve operated by a lever or a pedal by the operator, and a pilot valve (not shown) of the drift reduction valves 33 and 36 is also operated in conjunction with the pilot operation.

  Below, the content controlled by the said vehicle-mounted controller is demonstrated functionally.

  FIG. 1 shows a circuit state at the time of a boom lowering operation for lowering the boom 7 (FIG. 9), and the hydraulic oil pushed out from the head side of one boom cylinder 7c1 by the load of the work device 6 (FIG. 9) The control valve 61 is switched from the passage 34 to the communication position of the boom energy recovery valve 31 through the passage 32 and the drift reduction valve 33 and is communicated with the passage 68 and the passage 82 through the check valve 67. The pressure is accumulated in the accumulator 46 and is regenerated to the rod side of the boom cylinder 7c1 through the check valve 83, the passage 84 and the passage 39 via the regeneration control valve 63 switched from the passage 82 to the communication position.

  At this time, the control valve 61 sets the head of one of the boom cylinders 7c1 according to the lever operation amount, that is, the pilot pressure set by this operation amount and the accumulator pressure of the first accumulator 46 detected by the pressure sensor 55. The communication amount between the side and the first accumulator 46 side is switched. Specifically, the pilot pressure set by the operation amount of the lever is corrected by a predetermined table (converter) T1, and the accumulator pressure is corrected by a predetermined table (converter) T2, The integration result of is used as an output for operating the control valve 61. More specifically, in the present embodiment, as shown in FIG. 3, in table T1, when the pilot pressure set by the operation amount of the lever is relatively small, the output pressure relative to the increase amount of the input pressure In the region where the pilot pressure set by the lever operation amount exceeds the predetermined threshold TH1, the increase amount of the output pressure relative to the increase amount of the input pressure is suppressed more than when the threshold pressure TH1 or less. Further, the output pressure is set to be constant in a region exceeding a predetermined threshold TH2 which is larger than the predetermined threshold TH1. Further, in the table T2, in the region where the accumulator pressure is less than the predetermined threshold TH3, the gain increases with respect to the increase amount of the accumulator pressure, and in the region where the accumulator pressure exceeds the predetermined threshold TH3, the gain is constant (for example, 1) Set to At this time, the hydraulic oil does not return to the boom control valve 26 by the check valve 78.

  Further, the regeneration control valve 63 has one control valve 61 and one boom according to the operation amount of the lever, that is, the pilot pressure set by the operation amount and the accumulator pressure of the first accumulator 46 detected by the pressure sensor 55 The amount of communication between the cylinder 7c1 and the rod side is switched. Specifically, the pilot pressure set by the operation amount of the lever is corrected by a predetermined table (converter) T3 and the accumulator pressure is corrected by a predetermined table (converter) T4. The integration result of is used as an output for operating the regeneration control valve 63. More specifically, in the present embodiment, as shown in FIG. 5, in table T3, when the pilot pressure set by the operation amount of the lever is relatively small, the output pressure is proportional to the increase of the input pressure. Is increased, and the output pressure is set to be constant in a region where the pilot pressure set by the lever operation amount exceeds the predetermined threshold TH4. Further, in the table T4, the gain is set to be constant with respect to the increase amount of the accumulator pressure.

  At the same time, the hydraulic oil pushed out from the head side of the other boom cylinder 7c2 passes from the passage 37 via the passage 35 and the drift reduction valve 36 to the passage 73 to the passage 74 at the main control valve 62 of the boom energy recovery valve 31. The control oil is further controlled through the check valve 80 and the passage 40 to be regenerated on the rod side of the other boom cylinder 7c2, and the hydraulic oil branched through the check valve 80 to the passage 76 is checked in the main control valve 62. To the passage 75, and through the passage 39, the rod side of one boom cylinder 7c1 is regenerated. At this time, the operation amount of the main control valve 62 changes in accordance with the operation amount of the lever, that is, the pilot pressure set by the operation amount. Specifically, the pilot pressure set by the operation amount of the lever is corrected by a predetermined table (converter) T5, and the main control valve 62 is operated as an output. More specifically, in the present embodiment, as shown in FIG. 4, the input pressure and the output pressure of the pilot pressure set by the operation amount of the lever are set by the table T5 similar to the table T1 of FIG. Basically, when the boom lowering operation is detected, it is switched immediately. The excess flow rate of the hydraulic oil pushed out from the head side of the other boom cylinder 7c2 is returned from the control valve 26 for boom to the tank 21 through the passage 79, the passage 79 and the passage 30. Further, for example, when it is detected that the body 1 is lifted by lowering the boom by detecting the grounding of the working device 6 (FIG. 9) or the like based on the head pressure of the boom cylinders 7c1 and 7c2, predetermined set values Accordingly, the separation of the pressure accumulation cylinders of the boom cylinders 7c1 and 7c2 from the self-regeneration cylinders is released.

  Thus, the boom energy recovery valve 31 stores the pressure in the first accumulator 46 when the boom is lowered by the control valve 61, the regeneration control valve 63, and the main control valve 62, and the rod side of the boom cylinders 7c1 and 7c2. At the same time as the playback of the

  A part of the hydraulic fluid discharged from the main pump 12 at the time of the boom lowering operation is supplied to the rod side of the boom cylinder 7c1 from the output passage 38 via the passage 39 through the boom control valve 26. At this time, the boom control valve 26 maximizes the flow rate only during the initial operation of the boom lowering operation, and supplies the hydraulic oil to the rod side of the boom cylinder 7c1 through the output passage 38 and the passage 39. When the lowering starts, the hydraulic oil is regenerated from the head side of the boom cylinder 7c2 to the rod side of the boom cylinders 7c1 and 7c2, so the flow rate is reduced.

  Further, the pump flow rate from the main pump 12 controlled by the boom control valve 26 to the boom cylinder 7c1 is the lever operation amount, that is, the pilot pressure set by this operation amount and the accumulator pressure of the first accumulator 46 It is set according to Specifically, in the present embodiment, as shown in FIG. 6, this pump flow rate is set by the flow rate set by a predetermined table (converter) T6 according to the pilot pressure set by the operation amount of the lever. A minimum value of the flow rate set by a predetermined table (converter) T7 according to an elapsed time during a predetermined short time at the start of the boom lowering operation counted by the timer counter TC, for example 10 ms, and the timer Set by the acceleration flow rate and lever operation amount set by a predetermined table (converter) T8 according to the predetermined short time at the start of the boom lowering operation counted by the counter TC, for example 10 ms. The larger one of the integrated value with the gain set by the predetermined table (converter) T9 according to the pilot pressure to be set is set as the base flow rate. In the table T6, the flow rate is set constant in a region where the pilot pressure set by the operation amount of the lever is equal to or less than the predetermined threshold TH5, and the pilot pressure exceeds the predetermined threshold TH5 and is larger than the predetermined threshold TH5. In the following region, the flow rate decreases in proportion to the increase, and in the region exceeding the predetermined threshold TH6, the flow rate is set to be constant. In the table T7, the flow rate increases in proportion to the passage of time counted by the timer counter TC, and the flow rate is set to be constant when the time exceeds a predetermined threshold TH7. In the table T8, the flow rate increases in proportion to the passage of time counted by the timer counter TC, and the flow rate is set to be constant in a time exceeding the predetermined threshold TH8 and not more than the predetermined threshold TH8. When the time exceeds a predetermined threshold TH9, the flow rate decreases in proportion to the passage of time. In the table T9, the gain increases in proportion to the increase when the pilot pressure set by the operation amount of the lever is relatively small, and is set to be constant (for example, 1) in the region exceeding the predetermined threshold TH10.

  Then, as shown in FIG. 7, the flow rate obtained by integrating the gain set by the predetermined table (converter) T10 according to the accumulator pressure with respect to the above base flow rate is the above pump at the time of the boom lowering single operation When the lever operation of stick-in, stick-out, bucket-in and bucket-out is performed simultaneously with the boom lowering operation while being set as the flow rate, the predetermined table (according to the pilot pressure set by these operations) The flow rates set by the converters) T11 to T14 are added. In table T10, the gain is set to a constant (for example, 1) when the accumulator pressure is lower than a predetermined threshold TH11, and in a region exceeding the predetermined threshold TH11, the gain for the amount of increase when the accumulator pressure is relatively small In the region where the increase amount of is relatively large and the accumulator pressure is above the predetermined threshold TH11 and below the predetermined threshold TH12 which is larger than the predetermined threshold TH11, from when the gain increase amount with respect to the accumulator pressure increase is below the threshold TH11. Also, the gain is set to be constant (larger than 1) in a region exceeding a predetermined threshold TH13 which is larger than the predetermined threshold TH12. In Tables T11 to T14, in the region where the pilot pressure set by the lever operation amount is less than the predetermined threshold TH14, the increase in the flow rate is relatively large with respect to the increase, and the pilot pressure is the predetermined threshold In the region below the predetermined threshold TH15, which exceeds TH14 and is greater than the predetermined threshold TH14, the increase in flow rate with respect to the increase in pilot pressure is suppressed more than when the threshold TH14 or less, and in the region beyond the predetermined threshold TH15 The flow rate is set to be constant. The tables T11 to T14 may be the same table, or may be tables having different values of the threshold TH14 and the threshold TH15.

  2 shows a circuit state at the time of boom raising operation to raise the boom 7 (FIG. 9), and the boom energy recovery valve 31 at the time of boom raising operation shuts off the control valve 61 and the regeneration control valve 63. Switching to the main control valve 62 and stopping the accumulation of pressure in the first accumulator 46 and the regeneration of the boom cylinders 7c1 and 7c2 to the rod side, the main pump 12, 13 to the boom control valve 26, The hydraulic oil supplied to the passage 30 through the passage 28 is led from the passage 79 through the passage 37, the drift reduction valve 36 and the passage 35 to the head side of the other boom cylinder 7c2, and the check valve 78 to the passage 34, the drift reduction It leads to the head side of one boom cylinder 7c1 through the valve 33 and the passage 32. The hydraulic oil pushed out from the rod side of the boom cylinder 7c1 is returned from the passage 39 and the output passage 38 to the tank 21 through the boom control valve 26, and the hydraulic oil pushed out from the rod side of the boom cylinder 7c2 is It is directed to the passage 75 by the main control valve 62 through the passage 40 and the passage 76 and returns from the output passage 38 to the tank 21 through the boom control valve 26.

  Further, at the time of the boom lowering operation and the boom raising operation described above, the assist motor 15 having a motor function directly connected to the main pump shaft 14 or connected via a gear as the hydraulic motor as shown in FIG. The engine power assist can be performed to reduce the engine load. For example, at the time of boom lowering operation, engine power assist is performed when the pressure sensor 55 detects that the accumulator pressure of the first accumulator 46 accumulated via the control valve 61 is equal to or higher than a predetermined first threshold pressure. The pressure sensor 55 indicates that the accumulator pressure of the first accumulator 46 is equal to or higher than a predetermined second threshold pressure different from the predetermined first threshold pressure other than the boom lowering operation, for example, the boom raising operation. Engine power assist is performed when it detects by. At the time of this engine power assist, the electromagnetic switching valve 51 is switched to the communication position, the assist motor 15 is rotated by the energy accumulated in the first accumulator 46, and the hydraulic output of the main pumps 12, 13 is assisted. Reduce engine load. When the machine body 1 is lifted, the engine power assist by the assist motor 15 is not performed.

  Specifically, as shown in FIG. 8, it is set to 0 and 1 according to the time of the boom lowering single operation (boom lowering single state) and the operation other than the boom lowering operation (state other than the boom lowering). And the flag set according to the accumulator pressure by the predetermined table (converter) T15 corresponding to operations other than the boom lowering operation, and the predetermined table (converter) corresponding to the boom lowering operation The logical sum with the flag set according to the accumulator pressure is output as an assist flag by T16, and when the assist flag is on, ie, 1 the electromagnetic switching valve 51 is in the communication position, and off, ie, 0 for the electromagnetic The switching valve 51 is in the blocking position. In the table T15, a predetermined threshold value TH16 and a predetermined threshold value TH17 larger than the predetermined threshold value TH16 are set, and when the accumulator pressure increases, the flag switches from 0 to 1 when the threshold value TH17 or more. When it decreases, the flag is switched from 1 to 0 when it becomes equal to or less than the threshold TH16. Further, in the table T16, a predetermined threshold TH18 larger than the predetermined threshold TH17 and a predetermined threshold TH19 larger than the predetermined threshold TH18 are set, and the flag is 0 when the accumulator pressure is equal to or higher than the threshold TH19. When the accumulator pressure decreases, the flag switches from 1 to 0 when the accumulator pressure becomes lower than the threshold TH18. Therefore, these tables T15 and T16 are set with so-called hysteresis, in which the threshold value is different with respect to the increase and decrease of the accumulator pressure.

  As described above, the engine power assist function rotates the assist motor 15 by the energy accumulated in the first accumulator 46 from the head side of one boom cylinder 7c1, thereby the assist motor 15 via the main pump shaft 14 Thus, the load of the mounted engine 11 connected is reduced.

  As a result, for example, at the time of boom lowering operation, the control valve 61 is switched to the communication position, and the main control valve 62 is disconnected from the head side of the boom cylinders 7c1 and 7c2, and the head side of the boom cylinder 7c2 and the boom cylinders 7c1 and 7c2 The first sequence of forming the pressure accumulation circuit A and the regeneration circuit B by switching to a position communicating with the respective rod side of each of the two, and following this first sequence, accumulate pressure from the control valve 61 to the first accumulator 46 and By switching the control valve 63 to the communication position, a portion of the hydraulic fluid accumulated in the first accumulator 46 is regenerated on the rod side of the boom cylinder 7c1, and the boom pump cylinder from the main pump 12 via the boom control valve 26. After the supply of hydraulic oil to the rod side of 7c1 is increased for a short time and then squeezed in a second sequence, and following this second sequence, the first accumulator 46 stores And while a third sequence to rotate the assist motor 15 by utilizing the surplus of the accumulator is energy by switching the electromagnetic switch valve 51 to the communicating position is set.

  Then, as described above, when the pressure accumulating circuit A and the regenerating circuit B are separated to lower the work device 6 of the hydraulic shovel HE, a part (approximately half of the hydraulic oil pushed out from the head side of the boom cylinder 7c1 ) Is accumulated in the first accumulator 46 by the control valve 61, and the other portion (approximately the other half) of the hydraulic oil is regenerated to the rod side of the boom cylinder 7c1 by the regeneration control valve 63 of the auxiliary regeneration circuit C. Since the hydraulic fluid pushed out from the head side of 7c2 is regenerated to the rod side of the boom cylinders 7c1 and 7c2 by the main control valve 62, the regeneration flow rate of the main pumps 12 and 13 when the first accumulator 46 is accumulated. In addition, it is possible to easily secure the necessary pump flow rate including the main pump flow rate required by other hydraulic actuators with a simple configuration using control valves 61, 62, 63. 12, 13 can be miniaturized.

  Moreover, even when the boom cylinders 7c1 and 7c2 are interlocked with another hydraulic actuator (swing motor 3m, stick cylinder 8c, bucket cylinder 9c, etc.), the hydraulic fluid pushed out from the head side of the boom cylinder 7c1 by the auxiliary regeneration circuit C. Since a part of the hydraulic fluid is regenerated to the rod side of the boom cylinder 7c1 and the hydraulic oil pushed out from the head side of the boom cylinder 7c2 is regenerated to the rod side of the boom cylinders 7c1 and 7c2, the amount of oil for the regeneration is The pumps 12 and 13 can be turned to other hydraulic actuators, so that it is possible to prevent the speed decrease during interlocking operation, improve interlocking operability, and at the stroke end of the other hydraulic actuators, the boom cylinders 7c1 and 7c2 It is also possible to effectively prevent the boom 7 from falling sharply due to the rapid increase of the regeneration flow to the rod side of the.

  Further, at the initial movement of the boom lowering operation, since the hydraulic oil is supplied from the main pump 12 to the rod side of the boom cylinder 7c1 by the boom control valve 26, the initial movement speed at the boom lowering operation (at the contraction of the boom cylinders 7c1 and 7c2) Can be improved.

  Furthermore, rather than distributing the load of the working device 6 to the two boom cylinders 7c1 and 7c2 by turning a part of the oil on the head side of the boom cylinder 7c1 on one side to pressure accumulation to the first accumulator 46 By concentrating on one boom cylinder 7c1, the energy density can be increased, and the pressure generated from the boom cylinder 7c1 can be increased to increase the accumulated energy to the first accumulator 46, in other words, The components such as the first accumulator 46 and the assist motor 15 can be miniaturized, the cost can be reduced, and the layout can be facilitated.

  Further, the control valve 61 changes the communication amount between the head side of the boom cylinder 7c1 and the first accumulator 46 in accordance with the operation amount of the lever and the accumulator pressure of the first accumulator 46. Since the communication amount between the control valve 61 and the rod side of the boom cylinder 7c1 is changed in accordance with the lever operation amount and the accumulator pressure, the first operation can be more appropriately performed without sacrificing the operability of the boom lowering operation. Accumulator 46 can be accumulated to simultaneously satisfy operability and energy accumulation, and hydraulic oil is effectively regenerated to the rod side of boom cylinder 7c1, and main pump 12 to the rod side of boom cylinder 7c1, The flow rate of the hydraulic fluid discharged from 13 can be reduced, and the necessary pump flow rate can be secured more easily.

  Furthermore, with the boom energy recovery valve 31 in which a plurality of circuit functions are integrated into a single block, the layout is facilitated, and the cost can be reduced by reducing the number of assembling steps.

  In addition, by concentrating the load on one boom cylinder 7c1, the accumulated energy of the first accumulator 46 can be increased, and a large assist can be performed with a small accumulator, so that the cost can be reduced and the body layout can be compacted. Can.

  The present invention has industrial applicability to operators who manufacture, sell, etc., hydraulic circuits or work machines.

A pressure storage circuit B regeneration circuit C auxiliary regeneration circuit
HE Hydraulic excavator as one of the working machines 1 machine body 6 working equipment
7c1, 7c2 Boom cylinder as fluid pressure cylinder
12, 13 Main pump as a pump
46 Accumulator, the first accumulator
61 Control valve as the first valve
62 Main control valve as second valve
63 Regeneration control valve as third valve

Claims (3)

A plurality of fluid pressure cylinders to simultaneously operate the same operation by a pump or we subjected fed working fluid in pressure amount corresponding to the operation amount of the operating body,
An accumulator accumulated by the working fluid;
A first valve is provided to change the amount of communication between the head side of one fluid pressure cylinder and the accumulator among the plurality of fluid pressure cylinders according to the amount of operation of the operating body. An accumulator circuit that causes the accumulator to accumulator the working fluid pushed out from the head side of the fluid pressure cylinder;
The accumulator circuit blocks communication between the head sides of the plurality of fluid pressure cylinders when accumulating pressure in the accumulator, and at the same time, the head side of another fluid pressure cylinder among the plurality of fluid pressure cylinders and one of the other fluid pressure cylinders And a regeneration circuit for regenerating the working fluid pushed out from the head side of the other fluid pressure cylinder into one and the other fluid pressure cylinders via a second valve in communication with the rod side. ,
A third valve is provided to change the amount of communication between the first valve and the rod side of one fluid pressure cylinder according to the amount of operation of the operating body, and the accumulator circuit is connected to the accumulator via the third valve. A fluid pressure circuit comprising: an auxiliary regeneration circuit which regenerates a portion of the accumulated working fluid on the rod side of one fluid pressure cylinder. The first valve changes the communication amount between the head side of one fluid pressure cylinder and the accumulator according to the operation amount of the operating body and the accumulator pressure,
The fluid pressure according to claim 1, wherein the third valve changes the communication amount between the first valve and the rod side of one fluid pressure cylinder according to the operation amount of the operating body and the accumulator pressure. circuit. The aircraft,
A working device mounted on the machine,
A working machine comprising: the fluid pressure circuit according to claim 1 provided for a plurality of fluid pressure cylinders that move the working device up and down.

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