JP2014163419A - Energy recovery device and energy recovery method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energy recovery device and an energy recovery method capable of efficiently recovering energy of actuation fluid.SOLUTION: An energy recovery device includes a piston lateral chamber 2s in which the volume allowing actuation oil to be enclosed therein is variable and an inertia fluid chamber 2i. The inertia fluid chamber 2i includes a hydraulic cylinder 2 communicated with a high-pressure source HP and a low-pressure source LP, a high-pressure side switch 3H which performs communication and interception between the inertia fluid chamber 2i and the high-pressure source HP, a low-pressure side switch 3L which performs communication and interception between the inertia fluid chamber 2i and the low-pressure source LP, and a control part 5 which controls actuation of the low-pressure side switch 3L and the high-pressure side switch 3H. The control part 5 controls the low-pressure side switch 3L and the high-pressure side switch 3H so as to communicate the inertia fluid chamber 2i alternately to the high-pressure side switch 3H and the low-pressure side switch 3L when the volume of the piston lateral chamber 2s decreases.

Description

  The present invention relates to an energy recovery apparatus and an energy recovery method. More specifically, the present invention relates to an energy recovery device and an energy recovery method for regenerating energy that a fluid has.

  In a construction machine or the like, when a boom or an excavator is swiveled or a machine body is swung, a very large force is required, and therefore hydraulic pressure is used as the power. In a general hydraulic system adopted in such construction machines, a hydraulic pump is operated by an engine or the like to generate hydraulic pressure, and high pressure hydraulic oil is supplied to an actuator such as a cylinder or a hydraulic motor, so that a boom or A driving force for driving an excavator, a machine main body, and the like (hereinafter referred to as a driving target) is generated.

  On the other hand, when the actuator is operated as a brake when the operation of the drive target is stopped, the actuator absorbs the kinetic energy of the drive target. This absorbed energy is converted into hydraulic oil energy. For example, when the actuator is a hydraulic cylinder, the kinetic energy to be driven is converted to the energy of high-pressure hydraulic oil discharged from the hydraulic cylinder.

  When discharging the high-pressure hydraulic oil to the low-pressure tank, it is assumed that a pressure difference is generated between the hydraulic cylinder and the low-pressure tank due to the pressure loss of the throttle portion existing between the hydraulic cylinder and the low-pressure tank. Then, since the energy of the high-pressure hydraulic oil is consumed and discarded due to the pressure loss of the throttle portion, a regenerative system for recovering the energy of the high-pressure hydraulic oil has been developed.

  For example, the techniques of Patent Documents 1 to 3 adopt a configuration in which high-pressure hydraulic oil generated by a hydraulic motor is supplied to an accumulator to increase (accumulate pressure) in the accumulator and recover the energy of the hydraulic oil. doing.

  In Patent Documents 4 and 5, a hydraulic pressure line that connects the hydraulic pressure line and the pressure accumulator is connected to a hydraulic pressure line in HST (Hydro Static Transmission) in which a hydraulic pressure accumulator is stored in a pressure-holding state. Discloses a configuration in which a switching valve is provided. With such a configuration, by switching the switching valve, it is possible to hold the high oil pressure of the hydraulic pressure line in the accumulator, or to operate the hydraulic motor by the oil pressure held in the accumulator.

JP-A-11-350539 JP 2008-223817 A JP 2009-257389 A Japanese Patent Laid-Open No. 9-4709 Japanese Patent Laid-Open No. 11-6557

  However, the techniques of Patent Documents 1 to 3 recover the energy of the hydraulic oil or the like when the pressure in the accumulator or accumulator is lower than the hydraulic fluid generated by the hydraulic motor or the hydraulic fluid in the hydraulic line. However, energy cannot be recovered for a hydraulic pressure source having a pressure higher than that of hydraulic oil or the like.

  On the other hand, in the case of HST, if the flow rate of hydraulic fluid flowing through the hydraulic pressure line is decreased, energy can be recovered to the high pressure side against a large pressure with a small pressure, like a mechanical reduction gear. is there. That is, even if the pressure accumulator is higher than the hydraulic pressure line, the energy of the hydraulic oil can be recovered by the pressure accumulator. Specifically, after the hydraulic oil and the variable hydraulic pump are used to reduce the flow rate of the hydraulic oil discharged from the cylinder and raise the hydraulic oil to a high pressure, the hydraulic oil is supplied to a hydraulic source that is higher than the hydraulic cylinder pressure. The energy possessed by can be recovered.

  However, in the HST, a hydraulic motor and a hydraulic pump are provided in the hydraulic circuit, and the hydraulic motor and the pump must be operated in order to make the hydraulic oil higher than the high pressure source, so that the energy recovery efficiency is reduced. .

  If the hydraulic oil energy can be recovered to a high-pressure hydraulic power source without increasing the hydraulic oil pressure by operating the hydraulic motor and pump, the degree of freedom in recovering the energy of the hydraulic oil is improved. I think you can.

  In view of the above circumstances, an object of the present invention is to provide an energy recovery device and an energy recovery method capable of effectively recovering energy of a working fluid.

(Measuring method)
An energy recovery apparatus according to a first aspect of the present invention is an apparatus that recovers energy, and includes a fluid chamber in which a working fluid is enclosed and a variable volume, and an inertial fluid chamber communicated with the fluid chamber, the inertial fluid chamber An energy recovery unit that communicates with the high-pressure source and the low-pressure source, a high-pressure side switch that is provided between the inertial fluid chamber of the energy recovery unit and the high-pressure source, and that cuts off communication between the two, and the energy recovery unit A low-pressure side switch provided between the inertial fluid chamber of the unit and the low-pressure source, and a control unit for controlling the operation of the low-pressure side switch and the high-pressure side switch. The control unit is configured to cause the inertial fluid chamber to alternately communicate with the high-pressure source and the low-pressure source when the volume of the fluid chamber of the energy recovery unit becomes small. Controlling high-pressure side switch Characterized in that there.
The energy recovery device according to a second aspect of the present invention is the energy recovery apparatus according to the first aspect, wherein after the inertia fluid chamber of the energy recovery unit and the low-pressure source are communicated with each other by the low-pressure side switch, the control fluid is At the timing of flowing toward the source, the low-pressure side switch interrupts the inertial fluid chamber and the low-pressure source, and the high-pressure side switch connects the inertial fluid chamber and the high-pressure source. The low-pressure side switch and the high-pressure side switch are controlled so as to communicate with each other.
According to a third aspect of the present invention, in the first or second aspect of the invention, when the working fluid flows in the inertial fluid chamber toward the high-pressure source or the low-pressure source in the inertial fluid chamber, the energy recovery device rotates by the flow. An inertial rotator is provided.
(Energy recovery method)
An energy recovery method according to a fourth aspect of the present invention is a method for recovering energy by an energy recovery unit including a fluid chamber in which a working fluid is enclosed and a variable volume and an inertial fluid chamber communicated with the fluid chamber. When the volume of the fluid chamber of the energy recovery unit is reduced, the inertial fluid chamber is alternately communicated with a high pressure source and a low pressure source, and the working fluid flows out of the inertia fluid chamber to the low pressure source. The inertial fluid chamber and the low-pressure source are shut off, and the inertial fluid chamber and the high-pressure source are communicated with each other.
According to a fifth aspect of the present invention, there is provided an energy recovery method according to the fourth aspect, wherein the inertial fluid chamber rotates in response to the flow of the working fluid when the working fluid flows in the inertial fluid chamber toward the high pressure source or the low pressure source. A body is provided.

(Energy recovery device)
According to the first invention, when the volume of the fluid chamber of the energy recovery unit is reduced, if the low pressure source and the inertial fluid chamber communicate with each other, the working fluid flows from the fluid chamber into the inertial fluid chamber, and the inertial fluid chamber The working fluid flows from the low pressure source. In this state, if the inertial fluid chamber and the low-pressure source are shut off and the inertial fluid chamber and the high-pressure source communicate with each other, the working fluid has inertial energy. Even if the pressure is high, the working fluid flows from the inertial fluid chamber to the high-pressure source by the inertial force until the inertial energy disappears. Therefore, if an external force is input so as to reduce the volume of the fluid chamber of the energy recovery unit, the energy of the external force can be recovered to the high pressure source regardless of the pressure in the fluid chamber and the high pressure source.
According to the second invention, since the switch is switched at an appropriate timing, the energy of the external force input so as to reduce the volume of the fluid chamber of the energy recovery unit can be appropriately recovered in the high pressure source.
According to the third invention, the energy of the working fluid flowing out to the low pressure source can be stored as the rotational energy of the inertial rotating body. Then, the rotational inertia energy of the inertial rotating body can be changed to the inertial energy that causes the working fluid to flow into the high-pressure source, so that the energy recovery efficiency can be increased.
(Energy recovery method)
According to the fourth aspect of the present invention, when the volume of the fluid chamber of the energy recovery unit is reduced, the working fluid flows from the fluid chamber into the inertial fluid chamber when the low pressure source and the inertial fluid chamber communicate with each other. The working fluid flows from the low pressure source. In this state, if the inertial fluid chamber and the low-pressure source are shut off and the inertial fluid chamber and the high-pressure source communicate with each other, the working fluid has inertial energy. Even if the pressure is high, the working fluid flows from the inertial fluid chamber to the high-pressure source by the inertial force until the inertial energy disappears. Therefore, if an external force is input so as to reduce the volume of the fluid chamber of the energy recovery unit, the energy of the external force can be recovered to the high pressure source regardless of the pressure in the fluid chamber and the high pressure source.
According to the fifth aspect of the invention, the energy of the working fluid flowing out to the low pressure source can be stored as the rotational energy of the inertial rotating body. Then, the rotational inertia energy of the inertial rotating body can be changed to the inertial energy that causes the working fluid to flow into the high-pressure source, so that the energy recovery efficiency can be increased.

(A) is a schematic block diagram of the energy recovery apparatus 1 of this embodiment, (B) is a schematic block diagram of the energy recovery apparatus 1 provided with the inertia rotating body RP. It is a figure explaining energy recovery by energy recovery device 1 of this embodiment.

Next, an embodiment of the present invention will be described with reference to the drawings.
The energy recovery device of the present invention is a device that recovers energy held by a fluid, and is characterized in that energy is recovered by utilizing the inertial force of the fluid.

  The energy recovery apparatus of the present invention can be used as an apparatus for recovering energy of a working fluid flowing in a circuit in a fluid pressure system that operates equipment using a pressure motor, a cylinder, or the like. Examples of the working fluid include, but are not particularly limited to, hydraulic oil, water, and air.

  Hereinafter, in the hydraulic circuit connected to the hydraulic cylinder, a case where energy input to the hydraulic cylinder is converted into hydraulic oil energy and the energy of the hydraulic oil is recovered will be described.

(Energy recovery device of this embodiment)
As shown in FIG. 1, the energy recovery device 1 of this embodiment includes a hydraulic cylinder 2. The hydraulic cylinder 2 has a rod 2r protruding from the main body 2b, and energy can be supplied and input to and from the outside via the rod 2r.

  As shown in FIG. 1, the hydraulic cylinder 2 has a piston 2p to which the base end of a rod 2r is connected, and a space 2h inside the main body 2b is divided by the piston 2p. In the space 2h in the main body 2b divided by the piston 2p, the space (piston side chamber 2s) on the side where the piston 2p and the rod 2r are not connected is filled with hydraulic oil. The piston side chamber 2s corresponds to a fluid chamber referred to in the claims.

  As shown in FIG. 1, the main body 2b includes an inertial fluid chamber 2i that communicates with the piston-side chamber 2s. The inertial fluid chamber 2i is a hollow space having a smaller internal volume than the space 2h of the main body 2b. The inertial fluid chamber 2i is also filled with hydraulic oil in the same manner as the piston side chamber 2s.

  As shown in FIG. 1, a low pressure source LP is connected to the inertial fluid chamber 2i by a low pressure pipe PL. The low-pressure source LP is, for example, a tank for storing hydraulic oil, and is normally maintained at atmospheric pressure. That is, the hydraulic oil in the low pressure source LP is in an atmospheric pressure state.

  The low-pressure pipe PL is provided with a low-pressure side switch 3L. By opening and closing the low-pressure side switch 3L, the inertia fluid chamber 2i and the low-pressure source LP can be disconnected from each other. It has become.

  As shown in FIG. 1, a high pressure source HP is connected to the inertial fluid chamber 2i by a high pressure pipe PH. The high pressure source HP is, for example, a tank in which hydraulic oil having a pressure higher than that of the low pressure source LP is accumulated.

  The high-pressure pipe PH is provided with a high-pressure side switch 3H. By opening and closing the high-pressure side switch 3H, the inertia fluid chamber 2i and the high-pressure source HP can be disconnected from each other. ing.

  For this reason, if the high pressure side switch 3H is opened and the inertia fluid chamber 2i communicates with the high pressure source HP, high pressure hydraulic oil can be supplied from the high pressure source HP to the piston side chamber 2s via the inertia fluid chamber 2i. . Then, if the pressure of the high-pressure hydraulic oil is larger than the pressure applied toward the piston side chamber 2s via the piston 2p, the piston 2p can be moved so that the volume of the piston side chamber 2s is increased. It is.

  Moreover, in FIG. 1, the code | symbol 5 has shown the control part which controls the action | operation of the high voltage | pressure side switch 3H and the low voltage | pressure side switch 3L. The control unit 5 has a function of instructing the switching timing to the high voltage side switch 3H and the low voltage side switch 3L. Specifically, it has a function of controlling the opening and closing timing of the high voltage side switch 3H and the low voltage side switch 3L so that they are alternately opened.

(Description of energy recovery by the energy recovery apparatus 1 of the present embodiment)
Next, energy recovery by the energy recovery apparatus 1 of the present embodiment will be described.
As shown in FIG. 2, a case is considered where an external force F (hereinafter simply referred to as an external force F) that presses the rod 2r of the hydraulic cylinder 2 in the energy recovery device 1 of the present embodiment is applied.

  First, as shown in FIG. 2A, when the high pressure side switch 3H and the low pressure side switch 3L are closed, when this external force F is applied, the hydraulic oil in the piston side chamber 2s is pressurized by the piston 2p. The hydraulic oil in the piston side chamber 2s and the inertial fluid chamber 2i becomes high pressure. Then, the control unit 5 opens the low-pressure side switch 3L to allow the inertial fluid chamber 2i and the low-pressure source LP to communicate (FIG. 2B). Since the low pressure source LP is almost at atmospheric pressure, the hydraulic oil in the inertial fluid chamber 2i flows out from the inertial fluid chamber 2i toward the low pressure source LP. Then, a flow of hydraulic oil from the piston side chamber 2s to the inertial fluid chamber 2i is generated.

  When the hydraulic fluid flows out from the inertial fluid chamber 2i toward the low pressure source LP, the control unit 5 opens the high pressure side switch 3H to connect the inertial fluid chamber 2i and the high pressure source HP (FIG. 2C). At approximately the same time, the low pressure side switch 3L is closed to shut off the inertial fluid chamber 2i and the low pressure source LP. Then, the hydraulic oil in the inertial fluid chamber 2i flows out from the inertial fluid chamber 2i toward the high pressure source HP.

  Here, when the pressure of the high pressure source HP is lower than the pressure of the piston side chamber 2s, the hydraulic oil in the inertial fluid chamber 2i naturally flows out from the inertial fluid chamber 2i toward the high pressure source HP. In this case, the high-pressure source HP functions as a general accumulator.

  On the other hand, when the pressure of the high pressure source HP is higher than the pressure of the piston side chamber 2s, the hydraulic oil does not flow out from the inertia fluid chamber 2i toward the high pressure source HP due to the differential pressure between the two. However, as described above, the piston side chamber 2s includes the inertial fluid chamber 2i, and the operation oil flows from the inertial fluid chamber 2i toward the low pressure source LP, so that the operation from the piston side chamber 2s to the inertial fluid chamber 2i is performed. Oil flow is also occurring. Since the flow of this hydraulic oil has inertial energy, even if the low pressure source LP is closed, it does not stop at that moment. For this reason, it tends to flow out from the inertial fluid chamber 2i toward the high pressure source HP. The pressure of the high pressure source HP becomes a resistance to the flow of the hydraulic oil, but the hydraulic oil flows out from the inertial fluid chamber 2i toward the high pressure source HP until the hydraulic oil is decelerated and kinetic energy is lost. In other words, the hydraulic oil flows into the high pressure source HP from the inertial fluid chamber 2i. Then, in the high pressure source HP, even if the stored hydraulic fluid increases, the pressure of the hydraulic fluid does not decrease. Therefore, energy can be recovered in the high pressure source HP as much as the amount of hydraulic fluid increases. .

  Eventually, the flow from the inertial fluid chamber 2i toward the high-pressure source HP is slowed by the pressure of the high-pressure source HP, so that the inertial force of the hydraulic oil in the inertial fluid chamber 2i is reduced. Then, there is a possibility that the hydraulic oil flows backward from the high pressure source HP to the inertial fluid chamber 2i. Therefore, the control unit 5 closes the high-pressure side switch 3H to shut off the inertial fluid chamber 2i and the high-pressure source HP, and almost simultaneously opens the low-pressure side switch 3L to connect the inertial fluid chamber 2i and the low-pressure source LP. Communicate (FIG. 2D). Then, again, the working oil in the inertial fluid chamber 2i flows out from the inertial fluid chamber 2i toward the low pressure source LP, and inertial energy is generated in the working oil in the inertial fluid chamber 2i.

  When inertial energy is generated in the hydraulic fluid in the inertial fluid chamber 2i, the control unit 5 opens the high-pressure side switch 3H again to connect the inertial fluid chamber 2i and the high-pressure source HP, and at the same time, the low-pressure side switch 3L. Is closed to shut off the inertial fluid chamber 2i and the low pressure source LP (FIG. 2C). Then, the hydraulic oil in the inertial fluid chamber 2i flows out again from the inertial fluid chamber 2i toward the high pressure source HP. When the inertial force of the hydraulic oil in the inertial fluid chamber 2i decreases again, the control unit 5 closes the high-pressure side switch 3H to shut off the inertial fluid chamber 2i and the high-pressure source HP, and almost simultaneously opens the low-pressure side switch. The vessel 3L is opened to allow the inertial fluid chamber 2i to communicate with the low pressure source LP (FIG. 2D).

  As described above, according to the energy recovery device 1 of the present embodiment, the high-pressure side switch 3H and the low-pressure side switch 3L are repeatedly opened and closed, and the high-pressure side switch 3H and the low-pressure side switch 3L are alternately opened and closed. By doing so, the energy of the external force F can be recovered by the high pressure source HP.

(Description of energy recovery by the energy recovery apparatus 1 of the present embodiment)
In the above example, the case where the hydraulic oil is supplied to the high pressure source HP by the inertial force of the hydraulic oil has been described. Even in this case, while the hydraulic oil flows to the low pressure source LP, the energy of the hydraulic oil has Is not available. Therefore, it is preferable that the energy of the hydraulic oil flowing to the low pressure source LP can be used to flow the hydraulic oil to the high pressure source HP because the energy stored in the high pressure source HP can be increased.

  For example, as shown in FIG. 1B, when a flow of hydraulic oil toward the high-pressure source HP or the low-pressure source LP is generated in the inertial fluid chamber 2i in the inertial fluid chamber 2i, the inertial rotator rotates by the flow. RP is provided. Then, while the hydraulic oil is flowing through the low pressure source LP, the inertial rotating body RP is rotated by the flow. Therefore, the total kinetic energy due to the flow is the sum of the kinetic energy of the hydraulic oil and the rotational energy of the inertial rotating body RP. It becomes.

  On the other hand, when the inertial fluid chamber 2i is connected to the high-pressure source HP, the hydraulic oil in the inertial fluid chamber 2i flows toward the high-pressure source HP until the entire kinetic energy disappears due to the rotation of the inertial rotating body RP. That is, since the hydraulic oil can be supplied to the high-pressure source HP using not only the inertial energy of the hydraulic oil but also the energy generated by the rotation of the inertial rotating body RP, the energy is supplied to the high-pressure source HP with small speed fluctuations and small pressure fluctuations Can be stored.

  The inertial rotating body RP can use an impeller, a no-load small hydraulic motor, or the like, but is not particularly limited. Further, although a certain amount of energy can be stored only by the mass of the inertial rotating body RP, if a mass body capable of storing energy such as a flywheel is provided on the rotating shaft of the inertial rotating body RP, Fluctuation is reduced.

(About switching timing)
The period for switching the pressure source (that is, the high pressure source HP and the low pressure source LP) connected to the inertial fluid chamber 2i is not particularly limited. However, if there is no switching before the kinetic energy runs out and the high pressure source HP does not flow, a reverse flow occurs and the energy recovery efficiency decreases. On the other hand, if the switching cycle is such that no backflow occurs, generally the shorter the cycle, the smaller the fluctuations in flow rate and pressure, so the shorter the switching cycle is preferable in order to suppress vibration and the like.

  Further, the high pressure source HP and the low pressure source LP may be alternately connected to the inertial fluid chamber 2i, and the period in which the high pressure source HP and the low pressure source LP are connected to the inertial fluid chamber 2i within a certain time may not be the same period. . For example, the connection time to the high pressure source HP is T1, the connection time to the low pressure source LP is T2, and T1 / (T1 + T2) is the duty ratio. In this case, the connection time to the low pressure source may be T2 + (T2−T1) × duty ratio.

(About the high pressure side switch 3H and the low pressure side switch 3L)
The high pressure side switch 3H and the low pressure side switch 3L are not particularly limited as long as they can cut off communication between the inertial fluid chamber 2i and the high pressure source HP or the low pressure source LP. For example, a generally used solenoid valve that can be switched at high speed can be used. In addition, the high-voltage side switch 3H and the low-voltage side switch 3L can suppress vibrations and the like if the switching can be performed at a high speed as much as possible.

  The energy recovery apparatus of the present invention is suitable for an apparatus for recovering energy in a system in which a high-pressure working fluid is generated, such as a hydraulic system using a hydraulic cylinder.

DESCRIPTION OF SYMBOLS 1 Energy recovery apparatus 2 Cylinder 2h Space 2s Fluid chamber 2i Inertial fluid chamber 3H High pressure side switch 3L Low pressure side switch 5 Controller HP High pressure source LP Low pressure source PH High pressure piping PL Low pressure piping RP Inertial rotating body

Claims (5)

A device for recovering energy,
An energy recovery section including a fluid chamber in which a working fluid is enclosed and a variable volume, and an inertial fluid chamber communicated with the fluid chamber, the inertial fluid chamber being communicated with a high pressure source and a low pressure source;
A high-pressure side switch provided between the inertial fluid chamber of the energy recovery unit and the high-pressure source, and which cuts off communication between the two;
A low-pressure side switch provided between the inertial fluid chamber of the energy recovery unit and a low-pressure source, and that cuts off communication between the two;
A control unit for controlling the operation of the low-pressure side switch and the high-pressure side switch,
The controller is
Controlling the low-pressure side switch and the high-pressure side switch so that the inertial fluid chamber is alternately communicated with the high-pressure source and the low-pressure source when the volume of the fluid chamber of the energy recovery unit becomes small An energy recovery device characterized by being. The controller is
After the inertial fluid chamber of the energy recovery unit and the low pressure source are communicated with each other by the low pressure side switch, the inertial force is generated by the low pressure side switch at a timing when the working fluid flows toward the low pressure source. The low pressure side switch and the high pressure side switch are controlled such that the fluid chamber is disconnected from the low pressure source and the inertia fluid chamber and the high pressure source are communicated by the high pressure side switch. The energy recovery device according to claim 1, wherein the energy recovery device is a device. In the inertial fluid chamber,
3. An energy recovery apparatus according to claim 1, further comprising an inertia rotating body that rotates when the working fluid flows in the inertia fluid chamber toward the high pressure source or the low pressure source. . A method of recovering energy by an energy recovery unit comprising a fluid chamber in which a working fluid is enclosed and a variable volume and an inertial fluid chamber communicated with the fluid chamber,
When the volume of the fluid chamber of the energy recovery unit is reduced, the inertial fluid chamber is alternately communicated with a high pressure source and a low pressure source,
In a state where the working fluid flows from the inertial fluid chamber to the low-pressure source, the inertial fluid chamber and the low-pressure source are blocked, and the inertial fluid chamber and the high-pressure source are communicated. Energy recovery method. In the inertial fluid chamber,
5. The energy recovery method according to claim 4, further comprising: an inertia rotating body that rotates when the working fluid flows in the inertia fluid chamber toward the high pressure source or the low pressure source.

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