# US 2019/0169820 A1 · Energy regeneration device and work machine provided with energy regeneration device

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- Number: US 2019/0169820 A1
- Document ID: US20190169820A1
- Status: Published application
- Kind: A1
- Application number: 16/323,538
- Filed: 2017-08-09
- Published: 2019-06-06
- Earliest claimed: 2016-08-22
- Assignees: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
- Applicants: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
- Inventors: Naoki SUGANO; Satoshi MAEKAWA
- Web page: https://patentgrep.com/patent/US20190169820A1

## CPC

- E02F 9/2203: {Arrangements for controlling the attitude of actuators, e.g. speed, floating function}
- F15B 11/044: by means in the return line (F15B11/046, F15B11/05 take precedence)
- E02F 3/435: {for dipper-arms, backhoes or the like}
- E02F 9/20: Drives; Control devices (gearings in general F16H; controlling in general G05; electric multi-motor drives H02K, H02P)
- E02F 9/22: Hydraulic or pneumatic drives {(for dipper or bucket arm position control E02F3/43, for blade position control for graders E02F3/844; for turntables E02F9/121; for fork-lift trucks B66F9/22)}
- E02F 9/2217: {with energy recovery arrangements, e.g. using accumulators, flywheels}
- E02F 9/2253: {Controlling the travelling speed of vehicles, e.g. adjusting travelling speed according to implement loads, control of hydrostatic transmission}
- F15B 11/04: for controlling the speed (F15B11/024 takes precedence)
- F15B 11/08: with only one servomotor
- F15B 21/14: Energy-recuperation means
- E02F 3/32: working downwardly and towards the machine, e.g. with backhoes
- F15B 21/087: {Control strategy, e.g. with block diagram}
- F15B 2211/625: Accumulators
- F15B 2211/6306: representing a pressure
- F15B 2211/6313: the pressure being a load pressure
- F15B 2211/6346: representing a state of input means, e.g. joystick position
- F15B 2211/665: Methods of control using electronic components
- F15B 2211/6654: Flow rate control
- F15B 2211/7053: Double-acting output members
- F15B 2211/75: Control of speed of the output member
- F15B 2211/755: Control of acceleration or deceleration of the output member
- F15B 2211/88: Control measures for saving energy
- E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00)
- F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR

## Abstract

An energy regeneration device which can regenerate energy of a working fluid discharged from an actuator while controlling a flow rate of the working fluid, and a work machine including the device. The regeneration device includes a boom cylinder, an inertial fluid container, an oil tank, an accumulator, a low-pressure-side opening/closing device, and a high-pressure-side opening/closing device. A calculation unit calculates an opening area of each of the low-pressure-side opening/closing device and the high-pressure-side opening/closing device in accordance with a desired flow rate of a hydraulic fluid discharged from the boom cylinder. A regeneration control unit adjusts an opening area of each of the low-pressure-side opening/closing device and the high-pressure-side opening/closing device, and selects alternately the low-pressure-side opening/closing device and the high-pressure-side opening/closing device as a destination with which the inertial fluid container communicates, to supply a discharged hydraulic fluid to an accumulator.

## Claims

### Claim at position 1

1: An energy regeneration device for regenerating energy of a working fluid, comprising:
an actuator including a cylinder and a piston that is reciprocatable in the cylinder, the actuator being configured such that a volume of a cylinder fluid chamber delimited by the cylinder and the piston varies along with movement of the piston;
an inertial fluid container including a first internal space that is configured to communicate with the cylinder fluid chamber, the inertial fluid container being configured to receive the working fluid that is discharged from the cylinder fluid chamber due to the movement of the piston;
a low-pressure-side container including a second internal space that is set at a pressure lower than that of the cylinder fluid chamber and is configured to communicate with the first internal space of the inertial fluid container, the low-pressure-side container being configured to receive the working fluid flowing out of the inertial fluid container;
a high-pressure-side container including a third internal space that is set at a pressure higher than that of the second internal space of the low-pressure-side container and is configured to communicate with the first internal space of the inertial fluid container, the high-pressure-side container being configured to receive the working fluid flowing out of the inertial fluid container;
a low-pressure-side opening/closing device forming a low-pressure-side opening that is configured to permit circulation of the working fluid between the inertial fluid container and the low-pressure-side container, the low-pressure-side opening/closing device being configured to operate to vary an opening area of the low-pressure-side opening;
a high-pressure-side opening/closing device forming a high-pressure-side opening that is configured to permit circulation of the working fluid between the high-pressure-side container and the inertial fluid container, the high-pressure-side opening/closing device being configured to operate to vary an opening area of the high-pressure-side opening;
a first pressure obtaining unit configured to obtain a discharge pressure of the working fluid upstream of the inertial fluid container in flow of the working fluid flowing out of the cylinder fluid chamber;
a second pressure obtaining unit configured to obtain a high-pressure-side pressure of the working fluid downstream of the high-pressure-side opening/closing device in the flow of the working fluid flowing out of the cylinder fluid chamber;
a calculation unit configured to calculate a desired opening area of each of the high-pressure-side opening and the low-pressure-side opening for a case where the piston moves at a predetermined moving speed in such a direction as to reduce the volume of the cylinder fluid chamber, the calculation unit being configured to calculate the desired opening area of each of the high-pressure-side opening and the low-pressure-side opening based on a duty ratio for controlling an open time of each of the low-pressure-side opening and the high-pressure-side opening in a predetermined period, a desired flow rate of the working fluid discharged from the cylinder fluid chamber, the desired flow rate being set in accordance with the moving speed of the piston, the discharge pressure obtained by the first pressure obtaining unit, and the high-pressure-side pressure obtained by the second pressure obtaining unit; and
an opening/closing-device control unit configured to set the opening area of each of the high-pressure-side opening and the low-pressure-side opening to the desired opening area, and control an opening/closing operation of the high-pressure-side opening/closing device and the low-pressure-side opening/closing device in accordance with the duty ratio such that the low-pressure-side container and the high-pressure-side container are alternately selected as a destination with which the inertial fluid container communicates, to cause the working fluid to flow into the high-pressure-side container due to an inertial force that is generated in the first internal space of the inertial fluid container when the working fluid flows toward the low-pressure-side container, while causing the piston to move at the moving speed.

### Claim at position 2 (depends on 1)

2: The energy regeneration device according to claim 1, wherein
the opening/closing-device control unit sets the opening areas of the high-pressure-side opening and the low-pressure-side opening to an identical opening area in accordance with the desired flow rate of the working fluid, and
the calculation unit calculates the desired opening area A1 based on a relational formula of A1=Q1/(Cv×√(Ph−d1×Pacc)) in which A1 represents the desired opening area, Ph represents the discharge pressure of the working fluid, the discharge pressure being obtained by the first pressure obtaining unit, Pacc represents the high-pressure-side pressure of the working fluid, the high-pressure-side pressure being obtained by the second pressure obtaining unit, Q1 represents the desired flow rate of the working fluid, d1 represents the duty ratio, and Cv represents a constant that is previously set for the high-pressure-side opening/closing device and the low-pressure-side opening/closing device.

### Claim at position 3 (depends on 1)

3: The energy regeneration device according to claim 1, further comprising
a storage unit in which a threshold value that is previously set for the opening area of each of the high-pressure-side opening and the low-pressure-side opening is stored, wherein
when the desired opening area calculated by the calculation unit is equal to or smaller than the threshold value, the opening/closing-device control unit closes the high-pressure-side opening of the high-pressure-side opening/closing device and sets the opening area of the low-pressure-side opening of the low-pressure-side opening/closing device to an anti-backflow opening area that is previously set to a range equal to or larger than the threshold value.

### Claim at position 4 (depends on 2)

4: The energy regeneration device according to claim 2, further comprising
a storage unit in which a threshold value that is previously set for the opening area of each of the high-pressure-side opening and the low-pressure-side opening is stored, wherein
when the desired opening area calculated by the calculation unit is equal to or smaller than the threshold value, the calculation unit calculates the desired opening area by using the duty ratio that is set to zero in the relational formula, and the opening/closing control unit sets the opening area of the low-pressure-side opening of the low-pressure-side opening/closing device by using the desired opening area that is calculated, as the anti-backflow opening area.

### Claim at position 5 (depends on 1)

5: The energy regeneration device according to claim 1, wherein
the high-pressure-side container is an accumulator in which a pressure of the working fluid is accumulated.

### Claim at position 6 (depends on 1)

6: A work machine comprising:
an engine;
the energy regeneration device recited in claim 1;
a driven object connected to the piston of the actuator;
a pump being configured to be driven by the engine and drive the driven object connected to the piston by supplying the working fluid to the cylinder fluid chamber of the actuator; and
an operation lever configured to operate the driven object, wherein
the desired flow rate of the working fluid is set in accordance with an amount of operation of the operation lever.