JP6261002B2 - Fluid pressure circuit and work machine - Google Patents

Description

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

  In the work machine, the pressure oil discharged from the boom hydraulic cylinder when the boom is lowered is stored in the accumulator, and the pressure oil that is relieved from the swing hydraulic motor when the swing is accelerated or decelerated is also stored in the accumulator ( For example, see 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 cannot be regenerated into the boom hydraulic cylinder, so the necessary pump flow rate can be secured. Therefore, the operating speed of the boom hydraulic cylinder may be slow. Therefore, it is desired to regenerate the pressure oil discharged from the boom hydraulic cylinder with a simpler configuration to ensure the necessary pump flow rate.

  The present invention has been made in view of these points, and an object of the present invention is to provide a fluid pressure circuit and a work machine that can secure a necessary pump flow rate even when a working fluid is accumulated in an accumulator with a simpler configuration. And

According to the first aspect of the present invention, there are provided a plurality of fluid pressure cylinders that simultaneously operate the same operation by a working fluid pressurized and supplied from a pump according to an operation of an operating body, an accumulator that accumulates pressure by the working fluid, The fluid pressure cylinder head side and the accumulator are provided with one valve that changes the communication amount in accordance with the operation amount of the operating body, and pushed out from the head side of one fluid pressure cylinder through this one valve. An accumulator for accumulating the working fluid in the accumulator, and a head side of another fluid pressure cylinder among the plurality of fluid pressure cylinders while blocking communication between the head sides of the plurality of fluid pressure cylinders when accumulating the accumulator with the accumulator circuit accumulator by the accumulator circuit with varying according to the amount of operation of the communication amount operations of the first and respectively the rod side of the other hydraulic cylinder when Include other valve which communicates with the tank to the rod side of the plurality of fluid pressure cylinders when they are stopping the accumulator to chromatography data, through the other valve, extruded from the head side of the other hydraulic cylinder And a regeneration circuit that regenerates the working fluid to the rod side of one and other fluid pressure cylinders.

  According to a second aspect of the present invention, the one valve in the fluid pressure circuit according to the first aspect is configured such that the communication amount between the head side of the one fluid pressure cylinder and the accumulator corresponds to the operation amount of the operating body and the accumulator pressure. It is a fluid pressure circuit which changes.

  According to a third aspect of the present invention, there is provided an airframe, a work device mounted on the airframe, and a fluid pressure circuit according to claim 1 or 2 provided for a plurality of fluid pressure cylinders that move up and down the work device. Is a working machine.

  According to the first aspect of the present invention, the accumulator circuit and the regeneration circuit are separated from each other, and the working fluid pushed out from the head side of one fluid pressure cylinder is accumulated in the accumulator by one valve, and at the same time, another fluid pressure cylinder Since the working fluid pushed out from the head side is regenerated to the rod side of one and other fluid pressure cylinders by other valves, the pump flow rate corresponding to the regenerated flow rate can be saved even when accumulator is accumulating. The required pump flow rate can be easily secured with a simple configuration using this valve, and the pump can be downsized. In addition, by concentrating the load on a smaller number of fluid pressure cylinders rather than all of the plurality of fluid pressure cylinders, the pressure generated from the fluid pressure cylinder can be increased, and the accumulated energy of the accumulator can be increased, making the accumulator smaller. Can be

  According to the second aspect of the present invention, the one 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. Can accumulate pressure.

  According to the invention described in claim 3, when the accumulator is accumulating when lowering the working device of the work machine, the pump flow rate corresponding to the regeneration flow rate can be saved, and the necessary pump flow rate can be easily secured and the pump can be secured. In addition, by concentrating the load of the working device on a smaller number of fluid pressure cylinders rather than all of the plurality of fluid pressure cylinders, the pressure generated from the fluid pressure cylinders can be increased and the accumulated energy of the accumulator can be increased. The accumulator can be reduced in size.

It is a circuit diagram which shows the switching state of one Embodiment of the fluid pressure circuit which concerns on this invention. It is a circuit diagram which shows the other switching state of a circuit same as the above. (A) is explanatory drawing which shows typically the control algorithm of one valve | bulb of the same circuit, (b) is explanatory drawing which shows typically the control algorithm of the other valve | bulb of the same circuit. 1 is a perspective view showing an embodiment of a work machine according to the present invention.

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

  As shown in FIG. 4, a hydraulic excavator HE as a work machine is formed by a lower traveling body 2 and an upper revolving body 3 provided on the upper traveling body 3 so as to be turnable by a turning motor 3m. A machine room 4 in which an engine, a pump, and the like are mounted on the body 3, a cab 5 that protects an operator, and a work device 6 are mounted.

  In this working device 6, the base end of the boom 7 that is pivoted up and down by two boom cylinders 7 c 1 and 7 c 2 as fluid pressure cylinders arranged in parallel is pivotally supported on the upper swing body 3, and a stick is attached to the tip of the boom 7. A stick 8 rotated in the front-rear direction is pivotally supported by a cylinder 8c, and a bucket 9 rotated by a bucket cylinder 9c is pivotally supported at the tip of the stick 8. The two boom cylinders 7c1 and 7c2 are arranged side by side with respect to the common boom 7 and operate simultaneously in the same operation.

  In FIG. 1, the potential energy of the working device 6 is stored in the accumulator via the boom cylinder 7c1, and the kinetic energy of the upper swing body 3 is stored in the accumulator via the swing motor 3m and used for assisting the engine power. An engine power assist system is shown.

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

  An assist motor 15 is connected 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 directly or via a gear, and the main pumps 12 and 13 and the assist motor 15 are , Equipped with a swash plate that can variably adjust the pump / motor capacity (piston stroke) according to the angle, and its swash plate angle (tilt angle) is controlled by regulators 16, 17, 18 and swash plate angle sensor 16φ, Detection is performed by 17φ and 18φ, and regulators 16, 17 and 18 are controlled by electromagnetic 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) guided by the negative flow control passage 19nc, and the electromagnetic type of the negative flow control valve 19 It is possible to control with signals other than the negative control pressure by the switching valves 19a and 19b.

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

  This boom energy recovery valve 31 includes two accumulator circuits and a regeneration circuit B shown in FIG. 1 and hydraulic oil supplied from the main pumps 12 and 13 during boom raising operation shown in FIG. It is a composite valve that incorporates multiple circuit functions to switch between the circuits leading to the head side of 7c1 and 7c2 in a single block.

  A passage 32 drawn from the head side end of one boom cylinder 7c1 is connected to the boom energy recovery valve 31 by a passage 34 via a drift reduction valve 33, and a passage 35 drawn from the head side end of the other boom cylinder 7c2 is connected. Connection is made by a passage 37 through a 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. Each rod side of the boom cylinders 7c1 and 7c2 is connected to the boom energy recovery valve 31 through passages 39 and 40. The drift reduction valves 33 and 36 control the opening and closing and the opening degree between the ports by controlling the pilot pressure in the spring chamber by a pilot valve (not shown).

  One output passage 27 drawn out 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, an accumulator passage 47 provided with a plurality of first accumulators 46, a tank passage 50 and an electromagnetic switching valve 51 via a relief valve 48 and a check valve 49 are provided. Then, the suction side passage 52 is connected. A pressure sensor 55 that detects the pressure accumulated in the first accumulator 46 is connected to the accumulator passage 47. The tank passage 50 is connected to the tank 21 from the tank passage 56 via a check valve 57 with a spring and further via an oil cooler 58 or a check valve 59 with a spring. The first accumulator 46, accumulator passage 47, relief valve 48, electromagnetic switching valve 51, and pressure sensor 55 are incorporated in a single block to constitute an accumulator block 60.

  The boom energy recovery valve 31 is a main control valve which is a control valve 61 as one valve constituting a part of the accumulator circuit A and a boom circuit switching valve as another valve constituting a part of the regeneration circuit B. 62. These control valve 61 and main control valve 62 supply and discharge pilot pressure by an electromagnetic switching valve operated by operating a lever which is an operating body (not shown) operated by an operator such as in the cab 5 (FIG. 4). A pilot-operated type that is switched by control is used. However, in order to clarify the explanation, it is illustrated as an electromagnetic proportional directional control valve.

  The control valve 61 switches the communication between the passage 68 connected to the first accumulator 46 (accumulator block 60) via the check valve 67 and the passage 34, thereby switching the first accumulator 46 from the boom cylinder 7c1. This is a flow control valve that allows the accumulation of pressure. This control valve 61 is a valve that allows a larger amount of hydraulic oil to flow than returning from a normal cylinder (boom cylinders 7c1, 7c2, etc.) to the tank 21, and priority is given to storing pressure oil in the first accumulator 46. It has become.

  The main control valve 62 accumulates pressure between 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. The cylinder is separated into a self-reproducing cylinder and a self-reproducing cylinder. That is, when the main control valve 62 accumulates pressure in the first accumulator 46 by switching the control valve 61, the main control valve 62 cuts off the communication between the head sides of the boom cylinders 7c1 and 7c2, and the boom cylinder 7c2 head side and the boom cylinder 7c1 and 7c2 are configured to communicate with each rod side.

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

  As shown in FIG. 1, the pressure accumulating circuit A is connected to 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 side end of one boom cylinder 7c1. The circuit extends from the passage 68 to the first accumulator 46 through the check valve 67, and has a function of accumulating the oil pushed out from the head side of the boom cylinder 7c1 in the first accumulator 46.

  Further, the regeneration circuit B passes through the passage 35 drawn out from the head side end of the other boom cylinder 7c2 through the drift reduction valve 36 and the passage 37, to 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 to the passage 73 in the boom energy recovery valve 31, the main control It is a circuit that reaches the rod side end of one boom cylinder 7c1 through the 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 is pushed out from the head side of the boom cylinder 7c2. Has a function of regenerating the oil on the rod side of each of the boom cylinders 7c1 and 7c2.

  Relief valves 94, 95 opposite to each other are provided between the passages 92, 93 of the motor drive circuit C for connecting the turning control valve 91 for controlling the turning direction and speed of the turning motor 3m and the turning motor 3m. A check valve 97, 98 is provided, and between these relief valves 94, 95 and between the check valves 97, 98, a tank passage function for returning oil discharged from the motor drive circuit C to the tank 21, and a motor drive circuit C A makeup passage 99 having a makeup function capable of replenishing hydraulic oil is connected to the second accumulator 100. The makeup passage 99 is connected to a second accumulator 100 that supplies pressure oil. Then, hydraulic fluid is passed from the makeup passage 99 to the side of the passages 92 and 93 where there is a risk of vacuum generation via the check valves 97 and 98 at a pressure not exceeding the spring biasing pressure of the check valve 57 with spring. refill.

  Further, the passages 92 and 93 of the motor drive circuit C are communicated with the turning energy recovery passage 104 via the check valves 102 and 103, and the original pressure on the inlet side of the passage 104 is changed by the back pressure on the outlet side. The passage 106 is connected to the first accumulator 46 and the passage 68 through the difficult sequence valve 105.

  In the circuit configuration as described above, each swash plate angle sensor 16φ, 17φ, 18φ, pressure sensor 24, 25, 55 inputs the detected swash plate angle signal and pressure signal to an in-vehicle controller (not shown), The valves 42 and 51 are switched by an on / off operation or a proportional operation according to the drive signal according to a drive signal output from an in-vehicle controller (not shown). The boom control valves 26 and 28, the turning control valve 91, and other hydraulic actuator control valves (not shown) (for travel motors, stick cylinders, bucket cylinders, etc.) are provided in the cab 5 (FIG. 4). A pilot operation is performed by a so-called remote control valve, which is a manually operated valve operated by a lever or a pedal by an operator, and pilot valves (not shown) of the drift reduction valves 33 and 36 are also pilot operated in conjunction.

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

  FIG. 1 shows a circuit state during a boom lowering operation for lowering the boom 7, and hydraulic oil pushed out from the head side of one boom cylinder 7 c 1 due to a load of the work device 6 or the like passes through the passage 32 and the drift reduction valve 33. Then, the control valve 61 switched from the passage 34 to the communication position of the boom energy recovery valve 31 is communicated with the passage 68 through the check valve 67, and the first accumulator 46 is accumulated through the passage 68. At this time, the control valve 61 controls the head of one boom cylinder 7c1 in accordance with 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 lever operation amount is corrected by a predetermined table, and the accumulator pressure is corrected by a predetermined table. Output. More specifically, in the present embodiment, as shown in FIG. 3A, when the pilot pressure set by the lever operation amount is relatively small, the output pressure is increased with respect to the increase amount of the input pressure. In the region where the increase amount is relatively large and the pilot pressure set by the lever operation amount exceeds the predetermined threshold value TH1, the increase amount of the output pressure with respect to the increase amount of the input pressure is suppressed more than when it is less than the threshold value TH1. Further, the output pressure is set to be constant in a region exceeding a predetermined threshold value TH2 that is larger than the predetermined threshold value TH1. Further, in the region where the accumulator pressure is equal to or lower 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 set to be constant (for example, 1). . At this time, the hydraulic oil does not return to the boom control valve 26 side by the check valve 78.

  At the same time, the hydraulic oil pushed out from the head side of the other boom cylinder 7c2 passes from the passage 37 to the passage 74 through the passage 35 and the drift reduction valve 36 and from the passage 37 to the main control valve 62 of the boom energy recovery valve 31. The control oil is further regenerated to the rod side of the other boom cylinder 7c2 through the check valve 80 and the passage 40, and the hydraulic oil branched into the passage 76 through the check valve 80 is returned to the check valve in the main control valve 62. Then, the direction is controlled to the passage 75 and is also regenerated to the rod side of one boom cylinder 7c1 via the passage 39. At this time, the operation amount of the main control valve 62 changes according to the operation amount of the lever, that is, the pilot pressure set by the operation amount. Specifically, the pilot pressure set by the lever operation amount is corrected by a predetermined table to obtain an output for operating the main control valve 62. More specifically, in the present embodiment, as shown in FIG. 3B, the input pressure and the output of the pilot pressure set by the amount of operation of the lever by a table similar to the table of FIG. The pressure is set and basically switches immediately when a boom lowering operation is detected. The surplus flow rate of the hydraulic oil pushed out from the head side of the other boom cylinder 7c2 is returned from the boom control valve 26 to the tank 21 through the passage 37, the passage 79 and the passage 30. For example, when it is detected that the body 1 is being lifted by lowering the boom by detecting the grounding of the working device 6 (FIG. 4) based on the head pressure of the boom cylinders 7c1 and 7c2, a predetermined set value is set. Accordingly, the separation of the pressure accumulating cylinder and the self-regenerating cylinder of the boom cylinders 7c1 and 7c2 is released.

  In this way, the boom energy recovery valve 31 uses the control valve 61 and the main control valve 62 to accumulate pressure on the first accumulator 46 when the boom is lowered and to regenerate the boom cylinders 7c1 and 7c2 to the rod side. Do it at the same time.

  FIG. 2 shows a circuit state during a boom raising operation for raising the boom 7. The boom energy recovery valve 31 during the boom raising operation switches the control valve 61 to the cutoff position and switches the main control valve 62. The hydraulic oil supplied to the passage 30 from the main pumps 12 and 13 through the boom control valves 26 and 28 is stopped after the pressure accumulation in the first accumulator 46 and the regeneration of the boom cylinders 7c1 and 7c2 to the rod side are stopped. From the passage 79 to the head side of the other boom cylinder 7c2 through the passage 37, the drift reduction valve 36 and the passage 35, and from the check valve 78 to the one boom cylinder through the passage 34, the drift reduction valve 33 and the passage 32. Lead to the head side of 7c1. The hydraulic oil pushed out from the rod side of the boom cylinder 7c1 returns to the tank 21 via the boom control valve 26 from the passage 39 and the output passage 38, and the hydraulic oil pushed out from the rod side of the boom cylinder 7c2 The direction is controlled to the passage 75 by the main control valve 62 through the passage 40 and the passage 76, and is returned 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 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 functions as a hydraulic motor as shown in FIG. Thus, engine power assist can be performed to reduce the engine load. For example, when the boom lowering operation is performed, engine power assist is performed when the accumulator pressure of the first accumulator 46 detected by the pressure sensor 55 is equal to or higher than a predetermined first threshold pressure. For example, when the accumulator pressure of the first accumulator 46 detected by the pressure sensor 55 is equal to or higher than a predetermined second threshold pressure different from the predetermined first threshold pressure, engine power assist is performed. In 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 the engine load. Note that when the airframe 1 is lifted, engine power assist by the assist motor 15 is not performed.

  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, and this assist motor 15 causes the main pump shaft 14 to pass through. To reduce the load on the mounted engine 11 connected.

  As described above, when the pressure accumulating circuit A and the regeneration circuit B are separated and the working device 6 of the hydraulic excavator HE is lowered, the hydraulic oil pushed out from the head side of the boom cylinder 7c1 is controlled by the control valve 61. At the same time as accumulating in the accumulator 46, 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 by the main control valve 62, so that the first accumulator 46 is accumulated. In this case, the pump flow rate corresponding to the regeneration flow rate can be saved, and the necessary pump flow rate including the main pump flow rate required by other hydraulic actuators can be easily secured with the simple configuration using the control valves 61 and 62 and the main pump 12 , 13 can be miniaturized.

  Further, by turning the head side oil of the boom cylinder 7c1 on one side for accumulating the pressure on the first accumulator 46, that is, the load of the working device 6 is not distributed to the two boom cylinders 7c1 and 7c2, but one By concentrating on the boom cylinder 7c1, the energy density can be increased, the pressure generated from the boom cylinder 7c1 can be increased, and the accumulated energy in the first accumulator 46 can be increased, in other words, the first accumulator. Components such as 46 and assist motor 15 can be miniaturized, cost can be reduced, and 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 lever operation amount and the accumulator pressure of the first accumulator 46. The pressure can be more appropriately stored in the first accumulator 46 without sacrificing the operability, and the operability and the energy storage can be satisfied simultaneously.

  When the boom cylinders 7c1, 7c2 and other hydraulic actuators (swing motor 3m, stick cylinder 8c, bucket cylinder 9c, etc.) are operated in conjunction, the hydraulic oil pushed out from the head side of the boom cylinder 7c2 on one side is boom cylinders 7c1, 7c2. Because the oil is regenerated to the rod side, the amount of regenerated oil can be turned from the main pumps 12 and 13 to other hydraulic actuators, speed reduction during interlock operation can be prevented, and interlock operability can be improved. .

  Furthermore, the boom energy recovery valve 31 that integrates a plurality of circuit functions into a single block facilitates layout and enables cost reduction by reducing the number of assembly 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 accumulator can provide great assistance, thus reducing costs and making the aircraft layout compact. Can do.

  The present invention has industrial applicability to operators who manufacture and sell fluid pressure circuits or work machines.

A pressure accumulation circuit B regeneration circuit
HE Excavator as work machine 1 Airframe 6 Work device
7c1, 7c2 Boom cylinder as fluid pressure cylinder
12, 13 Main pump as a pump
46 The first accumulator that is an accumulator
61 Control valve as a single valve
62 Main control valve as other valve

Claims (3)

A plurality of fluid pressure cylinders that simultaneously operate the same operation by a working fluid pressurized and supplied from a pump according to the operation of the operating body;
An accumulator that accumulates pressure with the working fluid;
It is equipped with one valve that changes the amount of communication between the head side of one fluid pressure cylinder and the accumulator according to the amount of operation of the operating body, and is pushed out from the head side of one fluid pressure cylinder through this one valve. A pressure accumulation circuit for accumulating the accumulated working fluid in an accumulator;
While accumulating the accumulator by the pressure accumulator circuit, the communication between the head sides of the plurality of fluid pressure cylinders is interrupted, and the head side of the other fluid pressure cylinder among the plurality of fluid pressure cylinders and each of the one and other fluid pressure cylinders Other valves that connect the rod side of multiple fluid pressure cylinders to the tank when changing the amount of communication with the rod side according to the amount of operation of the operating body and stopping accumulator accumulation by the accumulator circuit And a regeneration circuit that regenerates the working fluid pushed out from the head side of another fluid pressure cylinder to the rod side of one and other fluid pressure cylinders through the other valve. Pressure circuit. The fluid pressure circuit according to claim 1, wherein the one valve changes a communication amount between the head side of the fluid pressure cylinder and the accumulator in accordance with an operation amount of the operation body and an accumulator pressure. The aircraft,
Working equipment mounted on the aircraft,
A working machine comprising: the fluid pressure circuit according to claim 1 or 2 provided for a plurality of fluid pressure cylinders that move up and down the work device.

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