JP2007040393A - Fluid pressure circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid pressure circuit which achieves effective energy recovery and regeneration. <P>SOLUTION: A variable displacement type regenerating motor 29 is arranged in an in-line manner in a return fluid passage 28 provided between a fluid pressure actuator 17 and a tank 22. An input shaft of a fixed displacement type regenerating pump 32 is connected to an output shaft of the regenerating motor 29 through a continuously variable transmission 31. A supply port 35 of a control valve 34 is connected to a discharge port of the regenerating pump 32 through a check valve 33. An output port 36 on one side of the control valve 34 is connected to an accumulator 37 for pressure accumulation. An output port 38 on the other side of the control valve 34 is connected to a main circuit 25 including a fluid pressure actuator 17 through a main pump 24. The control valve 34 is equipped with an energy charge position A, an energy discharge position B, an energy supply/discharge position C for supplying fluid pressure energy from the regenerating pump 32 to the main circuit 25 and discharging fluid pressure energy of the accumulator 37 to the main circuit 25, and an energy supply position D. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fluid pressure circuit that recovers and regenerates energy of a return fluid from a fluid pressure actuator.

  Among the excavator working devices, the energy stored as potential energy by raising the boom is converted into heat energy by the spool of the control valve in the return flow from the head side chamber of the boom cylinder when the boom is lowered. Released into the atmosphere. That is, all potential energy generated by raising the boom in the empty bucket state is discarded.

  On the other hand, there is an energy regeneration system in which the fluid pressure energy at the time of lowering the boom is accumulated in an accumulator by controlling the valve, and the accumulated fluid pressure energy is used by controlling the valve when driving another working device. .

In this conventional energy regeneration system, when the accumulator pressure is less than the set pressure, the valve is opened to accumulate excess energy from the higher pressure circuit to the accumulator, and when the accumulator pressure is greater than the set pressure, Is opened to supply regenerative energy to a lower pressure circuit (see, for example, Patent Document 1).
JP-A-5-287774 (first page, FIG. 1)

  In this conventional energy regeneration system, the accumulation and use of surplus energy in the accumulator is achieved only by the relative relationship between the pressure of the accumulator and the pressure of the circuit, so that it may be impossible to reuse depending on conditions. In this case, there is a problem that efficient energy recovery and regeneration cannot be expected.

  The present invention has been made in view of such a point, and an object thereof is to provide a fluid pressure circuit capable of efficient energy recovery and regeneration.

  The invention according to claim 1 is operated by the return fluid which is operated by the return fluid from the fluid pressure actuator and converts the return fluid energy which the return fluid has into rotational energy and collects it, and operates by the rotational energy input from the regeneration motor. A continuously variable transmission for continuously changing the rotational speed, a regeneration pump driven by rotational energy output from the continuously variable transmission, an accumulator for storing fluid pressure energy output from the regeneration pump, a regeneration pump and an accumulator A fluid pressure circuit comprising a control valve for controlling the direction of fluid pressure energy with a main circuit including the fluid pressure actuator.

  According to the second aspect of the present invention, the regenerative motor in the fluid pressure circuit according to the first aspect is a variable capacity motor capable of controlling the motor capacity in accordance with the state of the return fluid energy recovered from the fluid pressure actuator. is there.

  According to a third aspect of the present invention, the regeneration pump in the fluid pressure circuit according to the first or second aspect is a constant displacement pump with a constant pump capacity.

  According to a fourth aspect of the present invention, there is provided an energy charge position in which the control valve in the fluid pressure circuit according to any one of the first to third aspects stores the fluid pressure energy output from the regeneration pump in the accumulator, and the fluid stored in the accumulator. An energy discharge position for discharging pressure energy to the main circuit, an energy supply discharge position for supplying fluid pressure energy from the regeneration pump to the main circuit and discharging fluid pressure energy stored in the accumulator to the main circuit, And an energy supply position for supplying fluid pressure energy to the circuit.

  The invention according to claim 5 is a fluid pressure cylinder in which the fluid pressure actuator in the fluid pressure circuit according to any one of claims 1 to 4 is contracted by a load, and the regenerative motor is a cylinder of the fluid pressure cylinder. It is actuated by the return fluid from the head side chamber.

  According to the first aspect of the present invention, the regeneration motor converts the return fluid energy of the return fluid from the fluid pressure actuator into rotational energy, and the regeneration pump converts the rotational energy into fluid pressure energy. Is controlled by the control valve and stored in the accumulator or used in the main circuit, so that the accumulation and use of surplus energy is not limited as in the conventional energy regeneration system, and efficient energy recovery and regeneration can be achieved. In particular, the rotation speed of the regeneration pump can be controlled steplessly by the continuously variable transmission, and the charge flow rate to the accumulator or the main flow is controlled in order to control the rotational speed at which power is transmitted from the regeneration motor to the regeneration pump via the continuously variable transmission. The supply flow rate to the circuit can be arbitrarily controlled, and these components can be installed at any airframe position by driving the regeneration pump using the power of the regeneration motor.

  According to the second aspect of the present invention, since the regeneration motor is a variable displacement motor that can control the motor capacity in accordance with the state of the recovered return fluid energy, for example, when the return fluid has a small flow rate, the regeneration motor By controlling the flow rate to a small capacity, it is possible to obtain appropriate rotational energy according to the pressure and flow rate of the recovered return fluid energy.

  According to the third aspect of the present invention, by providing a continuously variable transmission between the regenerative motor and the regenerative pump, the variable capacity control function of the regenerative pump is abolished, and an inexpensive constant capacity pump is obtained. Can reduce costs.

  According to the fourth aspect of the present invention, the regenerated energy can be appropriately output to the main circuit by the control valve having four positions of the energy charge position, the energy discharge position, the energy supply discharge position, and the energy supply position. In particular, by providing a control valve having four positions and a continuously variable transmission, the working fluid is supplied in accordance with the remaining energy accumulated in the accumulator and so as not to cause a rapid flow rate change in the main circuit. It can be supplied, and operability failure due to a rapid flow rate change in the main circuit can be prevented.

  According to the fifth aspect of the present invention, when the fluid pressure cylinder is contracted by the load, the regenerative motor is operated by the return fluid from the cylinder head side chamber, thereby efficiently recovering the potential energy of the load. can do.

  Hereinafter, the present invention will be described in detail with reference to one embodiment shown in FIGS.

  FIG. 2 shows a hydraulic excavator 11 as a work machine. A front working device (hereinafter simply referred to as a work) is provided on an upper turning body 13 that is turnable with respect to a lower traveling body 12 together with a power device 14 such as an engine and a cab 15. 16). The working device 16 is provided with a fluid pressure actuator 17 capable of dropping by its own weight such as a boom cylinder.

  FIG. 1 shows a fluid pressure circuit 21 mounted on the hydraulic excavator 11, in which a working fluid in a tank 22, that is, a working oil, is operated by a main pump 24 driven by an engine 23. There is a basic circuit that supplies the circuit 25. The main circuit 25 includes a circuit for controlling the fluid pressure actuator 17 and another actuator circuit 26 for controlling other actuators such as an arm cylinder and a bucket cylinder.

  A circuit for controlling the fluid pressure actuator 17 such as a boom cylinder includes a direction switching valve 27, which causes the main pump 24 to transfer either the cylinder / head side chamber 17h or the cylinder / rod side chamber 17r of the fluid pressure actuator 17. The hydraulic pressure actuator 17 is controlled in its expansion and contraction direction by the direction switching valve 27 by supplying the working fluid under pressure and guiding the return fluid from the other side to the tank 22.

  For such a basic circuit, a regenerative motor 29 having a variable capacity control function such as a variable capacity hydraulic motor is provided in a return fluid passage 28 provided between the tank port of the direction switching valve 27 and the tank 22. Installed inline.

  An input shaft of a regeneration pump 32 such as a constant displacement hydraulic pump is connected to an output shaft of the regeneration motor 29 via a continuously variable transmission 31 having a continuously variable transmission function.

  A supply port 35 of a control valve 34 is communicated with a discharge port of the regeneration pump 32 via a check valve 33. One output port 36 of the control valve 34 is connected to an accumulator 37 for pressure accumulation, and the other The output port 38 is connected via a check valve 39 from the main pump 24 to the main circuit 25 including the fluid pressure actuator 17 and other actuator circuits 26.

  The regenerative motor 29 is operated by the return fluid from the fluid pressure actuator 17 and converts the return fluid energy of the return fluid into rotational energy and collects it. The capacity of the regeneration motor 29 is controlled according to the state of the recovered return fluid energy. By controlling the tilt angle of the swash plate 42 by the portion 41, the variable displacement motor is capable of controlling the motor capacity, and the motor capacity is controlled according to the operating speed of the fluid pressure actuator 17, that is, the return flow rate.

  A continuously variable transmission 31 interposed between the regenerative motor 29 and the regenerative pump 32 is provided with a shift control unit such as a V-belt continuously variable transmission mechanism, a toroidal continuously variable transmission mechanism, or a corn continuously variable transmission mechanism. Is a power transmission means capable of changing the speed ratio steplessly by a speed change control signal input to the control signal, and the speed ratio is designated from the outside.

  The regeneration pump 32 is a constant displacement pump that converts the rotational energy recovered by the regeneration motor 29 into fluid pressure energy. Since the pump capacity is constant, the regeneration pump 32 corresponds to the rotational speed input from the continuously variable transmission 31. Outputs pump discharge flow rate.

  The control valve 34 controls the direction of fluid pressure energy between the regeneration pump 32, the accumulator 37, and the main circuit 25, and stores the fluid pressure energy output from the regeneration pump 32 in the accumulator 37. A, an energy release position B for discharging the fluid pressure energy stored in the accumulator 37 to the main circuit 25, and supplying the fluid pressure energy from the regeneration pump 32 to the main circuit 25 and the fluid pressure energy stored in the accumulator 37 A movable valve body having an energy supply discharge position C for discharging to the main circuit 25 and an energy supply position D for supplying fluid pressure energy from the regeneration pump 32 to the main circuit 25 is provided. Position control units 45 and 46 are provided at both ends of the movable valve body.

  The accumulator 37 can store the fluid pressure energy output from the regeneration pump 32, and can send the working fluid having the fluid pressure energy from the accumulator 37 to the main circuit 25 for operating the working device.

  The switching control unit of the direction switching valve 27, the variable capacity control unit 41 of the regeneration motor 29, the transmission control unit of the continuously variable transmission 31, and the position control units 45 and 46 of the control valve 34 are electrically connected to the controller 47. This is controlled by the controller 47.

  In this way, the variable capacity regeneration motor 29 is installed in-line with respect to the return flow rate from the fluid pressure actuator 17 to the tank 22, and a constant displacement hydraulic pump or the like is connected to the regeneration motor 29 via the continuously variable transmission 31. Is connected to the discharge port of the regeneration pump 32 via a check valve 33 and a control valve 34, and the accumulator 37 is connected to the accumulator 37 by the control position of the control valve 34. This is a control system that feeds the working fluid or supplies the working fluid from the accumulator 37 to the main circuit 25 for operating the working device.

  Next, the operation of the illustrated embodiment will be described.

  When the direction switching valve 27 is switched to the left chamber and the fluid pressure actuator 17 having the potential energy due to the load W falls and moves by its own weight, it is pushed out from the cylinder / head side chamber 17h to the return fluid passage 28 through the direction switching valve 27. The return fluid rotates the regeneration motor 29. The regeneration motor 29 drives the regeneration pump 32 via the continuously variable transmission 31, and the regeneration pump 32 removes the working fluid in the tank 22 from the check valve 33. Then, it is supplied to the supply port 35 of the control valve 34.

  When the control valve 34 is controlled to the energy charge position A by the controller 47, the fluid pressure energy output from the regeneration pump 32 is accumulated in the accumulator 37.

  When the control valve 34 is controlled to the energy release position B by the controller 47, the fluid pressure energy stored in the accumulator 37 is released to the main circuit 25 via the check valve 39 and merges with the discharge flow rate of the main pump 24. Then, it is supplied to another actuator circuit 26.

  When the control valve 34 is controlled to the energy supply / release position C by the controller 47, fluid pressure energy is directly supplied from the regeneration pump 32 to the main circuit 25 via the check valve 39, and the fluid stored in the accumulator 37 is stored. Pressure energy is released to the main circuit 25 through the check valve 39.

  When the control valve 34 is controlled to the energy supply position D by the controller 47, fluid pressure energy is directly supplied from the regeneration pump 32 to the main circuit 25 via the check valve 39.

  The controller 47 controls the capacity by the capacity variable control unit 41 of the regeneration motor 29 in accordance with the flow rate and pressure of the return fluid in the return fluid passage 28 so as to obtain an appropriate rotation speed and output torque. For example, when the flow rate of the return fluid is small, the predetermined rotation speed is secured by controlling the capacity of the regeneration motor 29 to be small.

  The continuously variable transmission 31 controls the pump discharge flow rate by controlling the rotational speed of the regenerative pump 32 by controlling to the gear ratio instructed by the controller 47.

  Even after the accumulator 37 has completed accumulating, the regeneration pump 32 is appropriately controlled, and a working fluid having an energy larger than the accumulator capacity is sent from the regeneration pump 32 to the main circuit 25 for operating the working device.

  In this manner, the direction switching valve 27 opens the return fluid passage 28 between the cylinder / head side chamber 17h of the fluid pressure actuator 17 and the regeneration motor 29, and the regeneration motor 29 rotates by the potential energy of the fluid pressure actuator 17 due to the load W. To do. The rotation speed of the reproduction motor 29 is controlled by its variable capacity control function. The power generated by the regeneration motor 29 drives the regeneration pump 32 at a rotational speed controlled by the continuously variable transmission 31. The flow rate discharged from the regeneration pump 32 is guided to the control valve 34 via the check valve 33. The control valve 34 opens the circuit between the regeneration pump 32 and the energy accumulator 37 at the energy charge position A, charges the accumulator 37 with energy, and the main circuit from the accumulator 37 at the energy discharge position B. 25, energy is supplied to the main circuit 25 from the regeneration pump 32 at the energy supply / discharge position C, and the fluid pressure energy stored in the accumulator 37 is discharged to the main circuit 25. The energy is supplied from the regeneration pump 32 to the main circuit 25 at the energy supply position D. The position of these control valves 34 is controlled by a signal from the controller 47.

  Next, effects of the embodiment shown in FIG. 1 will be described.

  The regenerative motor 29 converts the return fluid energy of the return fluid from the fluid pressure actuator 17 into rotational energy, the regeneration pump 32 converts the rotational energy into fluid pressure energy, and the direction of the fluid pressure energy is controlled by the control valve 34. Then, since it is stored in the accumulator 37 or used in the main circuit 25, the energy collection and regeneration can be efficiently performed without limiting the accumulation and use of surplus energy as in the conventional energy regeneration system.

  In particular, the continuously variable transmission 31 can control the rotational speed of the regeneration pump 32 steplessly, and the rotational speed transmitted from the regeneration motor 29 to the regeneration pump 32 via the continuously variable transmission 31 is controlled. Even if the constant capacity type 32 is made inexpensive, the charge flow rate to the accumulator 37 or the supply flow rate to the main circuit 25 can be controlled arbitrarily.

  When the energy accumulated in the accumulator 37 is used up or is low and there is renewable energy, the working fluid supplied from the regenerative pump 32 by the continuously variable transmission 31 is joined to the main pump 24 while controlling the flow rate. Can be made.

  By driving the regenerative pump 32 using the power from the regenerative motor 29, these components can be installed at any position on the aircraft.

  Since the regenerative motor 29 is a variable displacement motor that can control the motor capacity according to the state of the recovered return fluid energy, for example, when the return fluid has a small flow rate, the regenerative motor 29 is controlled to a small capacity. Thus, appropriate rotational energy can be obtained according to the pressure and flow rate of the recovered return fluid energy.

  By interposing the continuously variable transmission 31 between the regenerative motor 29 and the regenerative pump 32, the capacity variable control function of the regenerative pump 32 can be abolished, and an inexpensive constant capacity pump can be obtained. I can plan. Furthermore, by providing a continuously variable transmission 31 between the regeneration motor 29 and the regeneration pump 32, the continuously variable transmission 31 amplifies the input to the regeneration pump 32 by the reduction ratio even when the output of the regeneration motor 29 is small. Therefore, the rotational energy suitable for accumulating the accumulator 37 can be controlled, and the continuously variable transmission 31 can appropriately control the rotational speed and input torque of the regeneration pump 32.

  Since the control valve 34 has four positions of an energy charge position A, an energy discharge position B, an energy supply discharge position C, and an energy supply position D, the regenerated energy can be appropriately output to the main circuit 25. .

  In particular, since the control valve 34 having the four positions and the continuously variable transmission 31 are provided side by side, there is no sudden flow rate change in the main circuit 25 in accordance with the remaining amount of energy accumulated in the accumulator 37. The working fluid can be supplied as described above, and operability failure due to a rapid flow rate change in the main circuit 25 can be prevented.

  At the energy supply / release position C of the control valve 34, the fluid pressure energy is supplied from the regeneration pump 32 to the main circuit 25 and the fluid pressure energy stored in the accumulator 37 is released to the main circuit 25. It is possible to cope with the case where the working fluid flow rate is required.

  When the direction switching valve 27 is switched to the left chamber and opened so that the fluid pressure cylinder as the fluid pressure actuator 17 is contracted by the load W, the regenerative motor 29 is returned by the return fluid discharged from the cylinder head side chamber 17h. By actuating, the potential energy of the load W can be efficiently recovered.

  Since the regeneration motor 29, the regeneration pump 32, the control valve 34, and the accumulator 37 perform energy recovery and regeneration using only fluid pressure without converting energy into electricity, there is no waste and high efficiency.

  In addition, this invention can be utilized also for other working machines other than a hydraulic shovel, for example, a loader, a crane, etc.

It is a circuit diagram showing one embodiment of a fluid pressure circuit concerning the present invention. It is a side view of the working machine carrying a fluid pressure circuit same as the above.

Explanation of symbols

17 Fluid pressure actuator
17h Cylinder head side chamber
25 Main circuit
29 Regenerative motor
31 continuously variable transmission
32 Regenerative pump
34 Control valve
37 Accumulator A Energy charge position B Energy release position C Energy supply release position D Energy supply position

Claims (5)

A regenerative motor that is actuated by a return fluid from a fluid pressure actuator and converts the return fluid energy of the return fluid into rotational energy and recovers it;
A continuously variable transmission that operates by rotational energy input from a regenerative motor and continuously changes the rotational speed;
A regeneration pump driven by rotational energy output from the continuously variable transmission;
An accumulator for storing fluid pressure energy output from the regenerative pump;
A fluid pressure circuit comprising: a regenerative pump, an accumulator, and a control valve that controls the direction of fluid pressure energy between the main circuit including the fluid pressure actuator. The fluid pressure circuit according to claim 1, wherein the regenerative motor is a variable displacement motor capable of controlling a motor capacity in accordance with a state of return fluid energy recovered from the fluid pressure actuator. The fluid pressure circuit according to claim 1 or 2, wherein the regenerative pump is a constant capacity pump with a constant pump capacity. The control valve
An energy charge position for storing the fluid pressure energy output from the regeneration pump in an accumulator;
An energy release position for releasing the fluid pressure energy stored in the accumulator to the main circuit;
An energy supply discharge position for supplying fluid pressure energy from the regeneration pump to the main circuit and discharging fluid pressure energy stored in the accumulator to the main circuit;
The fluid pressure circuit according to any one of claims 1 to 3, further comprising: an energy supply position for supplying fluid pressure energy from the regenerative pump to the main circuit. The fluid pressure actuator is a fluid pressure cylinder that is contracted by a load.
The fluid pressure circuit according to any one of claims 1 to 4, wherein the regenerative motor is actuated by a return fluid from a cylinder head side chamber of the fluid pressure cylinder.

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