JP2007162457A - Energy regeneration system for working machinery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy regeneration system for working machinery. <P>SOLUTION: A method and an apparatus improve regeneration efficiency when regenerating the energy of a discharge fluid from a fluid pressure actuator as electric energy. A displacement variable regenerating hydraulic motor is provided in a flow rate control line functioning as a discharge flow passage for oil discharged from a head side oil chamber of a hydraulic cylinder, and a flow rate of the discharge oil from the head side oil chamber of the hydraulic cylinder can be controlled by controlling the displacement of a regenerating hydraulic motor. A generator is further provided for generating electric power by the rotation of the regenerating hydraulic motor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present disclosure relates to a technical field of an energy regeneration system for a work machine that includes a fluid pressure actuator and regenerates energy of fluid discharged from the fluid pressure actuator.

  In general, work machines such as hydraulic excavators are provided with various types of fluid pressure actuators that are operated by pressurized fluid from a pump. Conventionally, a technique for regenerating the energy of fluid discharged from a fluid pressure actuator is known. For example, when the fluid pressure actuator is a hydraulic cylinder, there is a technique in which a regeneration circuit for supplying a part of oil discharged from the head side oil chamber of each hydraulic cylinder to the rod side oil chamber is provided. In another technique, the energy of oil discharged from each hydraulic cylinder is recovered in an accumulator.

  However, according to the technology including the regeneration circuit, it is possible to regenerate a part of the discharge oil from the head side oil chamber of the hydraulic cylinder, but most of the oil is directly bypassed to the oil tank, and as a result, There is a problem that energy regeneration efficiency is low. On the other hand, in the technology including the accumulator, there is a possibility that a larger energy storage capacity is required as compared with other energy storage means such as a battery, and furthermore, the energy storage time is shorter.

  As improvement means, (Patent Document 1) proposes a technique for regenerating and accumulating the energy of the fluid discharged from the pressure actuator as electric energy. In this technique, a turbine that is rotationally driven by inflow of discharge oil from a hydraulic cylinder is provided in a discharge flow path. Due to the driving force of this turbine, the generator generates electric energy, so that the energy of the discharged oil can be effectively regenerated and stored as electric energy, and this electric energy can be used as an alternative power source for the engine. It can be used and results in an environmentally friendly technology.

  On the other hand, a work machine such as a hydraulic excavator is generally configured such that the flow rate of oil discharged from a hydraulic cylinder is controlled by a control valve that performs meter-out control based on a throttle amount. In particular, in the technique disclosed in the above-mentioned reference patent application, a turbine that is rotationally driven by the inflow of discharged oil is provided on the downstream side of the control valve. Therefore, before the turbine rotates to regenerate energy, the control valve squeezes the oil discharged from the hydraulic cylinder to raise the temperature, thereby consuming energy, resulting in lower energy regeneration efficiency. The problem arises.

JP 2002-195218 A

  The present invention has been made in order to solve the above problems in view of the above-described circumstances.

  In one aspect, the present invention provides a work machine that includes a fluid pressure actuator that is adapted to operate by supplying / discharging a fluid, wherein the variable capacity regenerative fluid pressure motor discharges from the fluid pressure actuator. The flow rate of the discharge fluid from the fluid pressure actuator can be controlled by controlling the displacement of the regeneration fluid pressure motor, and the discharge fluid that rotates the regeneration fluid pressure motor. It is characterized in that an energy regeneration device for regenerating the energy as electrical energy is provided.

  In another form, the present invention provides a work machine. The work machine includes a hydraulic pump, a hydraulic system that is connected to the hydraulic pump, includes a hydraulic actuator having first and second supply / discharge ports, a discharge flow line from the hydraulic actuator, and an engine. The work machine further includes a variable displacement hydraulic motor that is fluidly disposed between the first and second supply / discharge ports and exposed to the fluid pressure of the discharge flow line, the variable displacement hydraulic motor comprising: The flow rate of the fluid discharged from the hydraulic actuator is controlled. The energy regeneration device is provided with a variable displacement hydraulic motor, and is operably coupled thereto, and the energy regeneration device supplies electric power for operating at least one of the engine and the hydraulic pump. It is configured.

  In yet another aspect, the present invention provides a method of operating a work machine power system. The method includes supplying power at least partially to a hydraulic pump via an internal combustion engine of the work machine and supplying hydraulic fluid to at least one hydraulic actuator of the work machine via the hydraulic pump. Furthermore, the method supplies power to the generator of the work machine at least partially through a step of discharging hydraulic fluid through a hydraulic motor located at least partially within a fluid discharge line of at least one hydraulic actuator. And at least partially supplying power to the hydraulic pump via power from the generator.

  In FIG. 1, reference numeral 1 indicates a hydraulic cylinder (for example, a boom hydraulic cylinder that moves a boom mounted on the hydraulic excavator in a vertical direction) provided in a work machine such as a hydraulic excavator. The cylinder 1 is a single rod type in which a rod side oil chamber 1b and a head side oil chamber 1c are formed on both sides of the piston 1a. The hydraulic cylinder is configured to contract when the pressure oil is supplied to the rod-side oil chamber 1b and discharged from the head-side oil chamber 1c to move the piston 1a in the direction of application of the weight load W. Furthermore, the hydraulic cylinder 1 extends when supplying pressure oil to the head side oil chamber 1c and discharging oil from the rod side oil chamber 1b, and moves the piston 1a in the direction opposite to the direction in which the weight load W is applied. Designed to.

  Reference numeral 2 indicates a hydraulic pump as a pressure oil supply source for the hydraulic cylinder 1. Here, the hydraulic circuit between the hydraulic pump 2 and the hydraulic cylinder 1 includes a discharge line 3 connected to the discharge side of the hydraulic pump 2, a flow rate control circuit 4 connected to the downstream side of the discharge line 3, The flow control circuit 4 and the rod side oil chamber 1b of the hydraulic cylinder 1 are connected to the rod side line 5, and the flow control circuit 4 and the hydraulic cylinder 1 are connected to the head side oil chamber 1c. A head side line 6 is provided.

  In the middle part of the discharge line 3, a return line 8 to the oil tank 7 is formed by branching, and in this return line 8, a bypass valve is operated so as to operate based on a command from the control device 10, as will be described later. 9 is arranged. Further, a check valve 11 is disposed in the discharge line 3 downstream of the branch point of the return line 8, and this check valve 11 prevents the oil from flowing back to the hydraulic pump 2 and the return line 8. Yes.

  The flow control circuit 4 is formed by connecting the first, second, third, and fourth flow control lines 12, 13, 14, and 15 in a rectangular ring shape. Here, the discharge line 3 is connected to a connection portion A between the first flow rate control line 12 and the second flow rate control line 13, and the rod side line 5 is connected to the first flow rate control line 12 and the third flow rate control line 12. The head side line 6 is connected to a connection portion C between the second flow rate control line 13 and the fourth flow rate control line 15 and is connected to an oil tank. The discharge line 16 reaching 7 is connected to a connection portion D between the third flow rate control line 14 and the fourth flow rate control line 15.

  In the first flow rate control line 12, a rod side meter-in valve 17 adapted to control the flow rate of supply oil from the discharge line 3 to the rod side line 5 is disposed. In the second flow rate control line 13, a head side meter-in valve 18 adapted to control the flow rate of oil supplied from the discharge line 3 to the head side line 6 is disposed. In the third flow rate control line 14, a rod side meter-out valve 19 configured to control the flow rate of discharged oil from the rod side line 5 to the discharge line 16 is disposed. The rod side meter-in valve 17, the head side meter-in valve 18, and the rod side meter-out valve 19 are configured to operate based on a command from the control device 10.

  Further, a variable capacity regenerative hydraulic motor 20 is arranged in the fourth flow rate control line 15. The displacement of the regenerative hydraulic motor 20 changes from zero to a predetermined maximum value based on the control command output from the control device 10 to the displacement control means 20a, and thereby the flow rate in the fourth flow control line 15 is changed. The flow rate is changed from zero to a predetermined maximum value, and then the flow rate control (meter-out control) of the discharged oil from the head side line 6 to the discharge line 16 is enabled by changing the displacement of the regenerative hydraulic motor 20. Furthermore, the generator 21 is connected in conjunction with the regenerative hydraulic motor 20, where the generator 21 can be driven by the torque of the regenerative hydraulic motor 20 to generate electric power.

  The third and fourth flow control lines 14 and 15 are also provided with a rod-side meter-out valve 19 and bypass lines 14a and 15a for bypassing the regenerative hydraulic motor 20, respectively. 14a and 15a are provided with check valves 51 and 22 that enable oil flow from the discharge line 16 to the rod side line 5 and the head side line 6 but prevent backflow, respectively. For this reason, the replenishment of oil from the oil tank 7 is performed when the rod side line 5 or the head side line 6 is in a vacuum state.

  On the other hand, the control device 10 is constituted by a microcomputer or the like, receives a command signal output from the control lever 23 for the hydraulic cylinder 1, and then, based on this command signal, the displacement control means 2a for the displacement of the hydraulic pump 2. The control command is output to the bypass valve 9, the rod-side meter-in valve 17, the head-side meter-in valve 18, the rod-side meter-out valve 19, the displacement control means 20a of the regenerative hydraulic motor 20, and the like.

  Regarding the control command output from the control device 10, when the control lever 23 for the hydraulic cylinder 1 is in the stop position (that is, no operation is performed in the control lever 23), the control device 10 determines that “valve opening”. ”Is output to the bypass valve 9, and the“ close valve ”control command is output to the rod-side meter-in valve 17, the head-side meter-in valve 18, and the rod-side meter-out valve 19. Is output to the displacement control means 20a of the regenerative hydraulic motor 20. For this reason, the oil forcibly delivered from the hydraulic pump 2 is returned to the oil tank 7 through the return line 8, and the first to fourth flow control lines 12 to 15 are in a closed state. Therefore, there is no oil supplied / discharged to / from the hydraulic cylinder 1, and therefore the hydraulic cylinder 1 is stopped.

  On the other hand, when the control lever 23 is operated so as to be in a position indicating the extension of the hydraulic cylinder 1, the control device 10 outputs a control command of “valve closing” to the bypass valve 9 and “opens the valve”. ”Is output to the head-side meter-in valve 18 and the rod-side meter-out valve 19, the“ valve closing ”control command is output to the rod-side meter-in valve 17, and the“ displacement zero ”control command is further reproduced. It outputs to the displacement control means 20a of the motor 20 displacement. In this case, the opening amounts of the head-side meter-in valve 18 and the rod-side meter-out valve 19 are controlled so as to increase or decrease in accordance with the increase or decrease of the operation amount of the control lever 23.

  Therefore, the oil forcibly delivered from the hydraulic pump 2 flows to the second flow rate control line 13 through the discharge line 3, and then the oil flow rate passes through the head side line 6 to the head of the hydraulic cylinder 1. The head side meter-in valve 18 arranged in the second flow rate control line 13 is controlled so as to be supplied to the side oil chamber 1c. On the other hand, the discharged oil from the rod side oil chamber 1b flows to the third flow rate control line 14 through the rod side line 5, and then the third flow rate so that the oil flow rate flows to the oil tank 7 through the discharge line 16. It is controlled by a rod side meter-out valve 19 arranged in the flow rate control line 14. Thus, by supplying the pressure oil to the head side oil chamber 1c and discharging the oil from the rod side oil chamber 1b, the piston 1a is moved in the direction opposite to the application direction of the weight load W, and the hydraulic cylinder 1 is moved. Elongate.

  When the control lever 23 is operated so as to be in a position indicating the contraction of the hydraulic cylinder 1, the control device 10 outputs a “valve closing” control command to the bypass valve 9 and “valve open”. Is output to the rod-side meter-in valve 17 and the head-side meter-in valve 18, and a “valve closing” control command is output to the rod-side meter-out valve 19. In this case, the opening amount of the rod-side meter-in valve 17 is controlled so as to increase or decrease in accordance with the increase or decrease of the operation amount of the control lever 23. Furthermore, the control device 10 outputs a control command to the displacement control means 20a of the regenerative hydraulic motor 20 so that the displacement increases or decreases according to the increase or decrease of the operation amount of the control lever 23.

  Accordingly, the oil forcedly sent from the hydraulic pump 2 flows to the first flow rate control line 12 through the discharge line 3, and then the oil flow rate passes through the rod side line 5 to the rod side oil chamber 1 b of the hydraulic cylinder 1. Is controlled by a rod-side meter-in valve 17 disposed in the first flow rate control line 12. On the other hand, the discharged oil from the head side oil chamber 1c flows through the head side line 6 and is separated into the second flow rate control line 13 and the fourth flow rate control line 15 at the connection portion C. Thereafter, the discharge oil flowing in the second flow rate control line 13 merges with the pressure oil from the discharge line 3 at the connection portion A, and as a regenerated oil passing through the first flow rate control line 12 and the rod side line 5, the hydraulic cylinder 1 rod-side oil chamber 1b. On the other hand, the oil flow rate in the fourth flow rate control line 15 is controlled by the regenerative hydraulic motor 20 so as to flow to the oil tank 7 through the discharge line 16. Thus, the pressure oil is supplied to the rod side oil chamber 1b and the oil is discharged from the head side oil chamber 1c, whereby the piston 1a is moved in the application direction of the weight load W and the hydraulic cylinder 1 is contracted.

  Further, when the regenerative hydraulic motor 20 arranged in the fourth flow rate control line 15 that functions as a discharge flow path from the hydraulic cylinder 1 rotates when the hydraulic cylinder 1 is contracted, the generator 21 is driven to generate electric power. Then, this electric power is used for the fuel cell device 25 configured to supply electric power to the motor 24 as a power source for the hydraulic pump 2.

  The fuel cell device 25 includes an electrolytic bath 26 for electrolyzed water, a hydrogen storage device 27 containing a hydrogen storage alloy for absorbing hydrogen generated in the electrolytic bath 26, a fuel cell 28, and the like. The generator 21 is connected to the electrolytic cell 26 via a power supply path 29. The electrolytic cell 26 electrolyzes water using the power supplied from the generator 21 to generate hydrogen and oxygen. Thereafter, hydrogen and oxygen are used as fuel for the fuel cell 28 to generate electric power, and this electric power is supplied to the motor 24 to serve as a power source for driving the hydraulic pump 2. In this case, once the hydrogen generated in the electrolytic cell 26 is stored in the hydrogen storage device 27, long-term energy storage is possible. In FIG. 1, reference numeral 30 indicates a return water path for returning water generated together with electric power in the fuel cell 28 to the electrolyzer 26, and water is reused by providing the return water path 30. It becomes possible. Reference numeral 37 indicates a hydrogen flow path, while reference numeral 36 indicates an oxygen flow path. Reference numeral 39 identifies an air supply port.

  In addition, the output of the motor 24 is optimally controlled by adopting a configuration in which the amount of hydrogen supplied from the hydrogen storage device 27 to the fuel cell 28 is controlled so that the power generation of the fuel cell 28 can be controlled. be able to.

  Next, 2nd-4th embodiment of this invention is described with reference to each of FIGS. Note that in the second to fourth embodiments, the same (same) components as those shown in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. .

  First, regarding the second embodiment shown in FIG. 2, the fuel cell device 25 includes a reforming device 31 that generates hydrogen using a chemical fuel such as methanol, ethanol, or LPG as a raw material. Here, the hydrogen generated by the reformer 31 merges with the hydrogen from the hydrogen storage device 27 described above and is supplied to the fuel cell 28. Thus, by providing the reforming device 31, hydrogen can be sufficiently supplied to the fuel cell 28 without increasing the size of the hydrogen storage device 27.

  Further, in the third embodiment shown in FIG. 3, the fuel cell device is not provided, but the capacitor 32 and the storage battery 33 for storing the power generated by the generator 21 and the storage battery 33 are supplied. An inverter 34 that converts DC power into AC power and controls the voltage is provided. Here, the motor 24 is driven by the electric power supplied from the inverter 34.

  Furthermore, in the first to third embodiments, the motor 24 is used as a power source for driving the hydraulic pump 2. However, in the case of a work machine equipped with a plurality of hydraulic actuators such as construction machines, the regeneration energy of the oil discharged from the hydraulic cylinder 1 becomes insufficient, and the size of the power storage device such as a storage battery is too large. It may be made so large that it is difficult to install in Here, in the fourth embodiment shown in FIG. 4, the engine 35 is mounted as a power source for the hydraulic pump 2, and the motor 24 is used as an auxiliary power source for supporting the engine 35. Thus, by using the motor 24 as an auxiliary power source, it is possible to reduce the amount of fossil fuel consumed by the engine 35, which can contribute to energy saving and environmentally. This is preferable.

  In the first embodiment configured as described above, when the hydraulic cylinder 1 is contracted, the pressure oil is supplied to the rod side oil chamber 1b and the oil is discharged from the head side oil chamber 1c. Become so. The oil discharged from the head side oil chamber 1c has a high pressure due to the application of the weight load W, and the pressure receiving area of the piston 1a facing the head side oil chamber 1c is the cross-sectional integral of the rod 1d, the rod side oil. Because the pressure is larger than the pressure receiving surface of the piston 1a facing the chamber 1b, a larger amount of oil than the pressure oil supplied to the rod side oil chamber 1b is discharged from the head side oil chamber 1c. . As described above, a part of the oil discharged from the head side oil chamber 1c is regenerated oil as the head side line 6, the second flow rate control line 13, the first flow rate control line 12, and the rod side line. 5 is supplied to the rod side oil chamber 1b. On the other hand, the remainder of the discharged oil is subjected to flow rate control (meter-out control) by the variable capacity regenerative hydraulic motor 20 disposed in the fourth flow rate control line 15. This oil is discharged to the oil tank 7 through the discharge line 16, and the generator 21 is driven by the rotation of the regenerative hydraulic motor 20 to generate electric power. Thereafter, this electric power can be used as a power source for the hydraulic pump 2 in the fuel cell device 25 adapted to supply electric power to the motor 24.

  As described above, in the present embodiment, the regenerative hydraulic motor 20 rotates by the inflow of discharge oil from the head side oil chamber 1 c of the hydraulic cylinder 1, and the generator 21 generates electric power by the rotational drive of the regenerative hydraulic motor 20. Thus, the energy of the discharged oil can be regenerated as electric energy. The regenerative hydraulic motor 20 not only drives the generator 21 but also controls the flow rate of the oil discharged from the hydraulic cylinder 1.

  Accordingly, there is no need to provide a control valve for controlling the flow rate in the discharge flow path of the hydraulic cylinder 1, and as a result, there is no energy loss when passing through the control valve. The energy regeneration efficiency can be improved.

  In the above-described embodiment, the hydraulic cylinder is illustrated as a fluid pressure actuator. However, the embodiment can be applied to a hydraulic motor, and can be applied not only to the hydraulic pressure but also to a pressurized fluid in a pneumatic field in a wide range. It should be noted that there are.

  Further, in the above-described embodiment, the electric energy obtained by regenerating the energy of the fluid discharged from the fluid pressure actuator is used for a motor for driving a pump configured to supply pressurized fluid to the fluid pressure actuator. However, the present embodiment is not limited to this, and it is obvious that the present embodiment can be used for various types of electric machines mounted on work machines.

  This description is for purposes of illustration only and should not be construed to narrow the scope of the disclosure in any way. Therefore, those skilled in the art will appreciate that various modifications can be made to the embodiments of the present disclosure without departing from the intended spirit and scope of the present disclosure. Other aspects, features, and advantages will be apparent from a review of the accompanying drawings and the appended claims.

1 is a diagram illustrating an energy regeneration system according to a first embodiment of the present disclosure. FIG. It is a figure which shows the energy regeneration system which concerns on 2nd Embodiment of this indication content, and attaches | subjects the similar number to the similar element with respect to FIG. It is a figure which shows the energy regeneration system which concerns on 3rd Embodiment of this indication, and attaches | subjects the similar number with respect to FIG.1 and FIG.2 with a similar element. It is a figure which shows the energy regeneration system which concerns on 4th Embodiment of this indication content, and attaches | subjects the similar number with respect to FIGS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic cylinder 1a Piston 1b Rod side oil chamber 1c Head side oil chamber 1d Rod 2 Hydraulic pump 2a Displacement capacity control means 3 Discharge line 4 Flow control circuit 5 Rod side line 6 Head side line 7 Oil tank 8 Return line 9 Bypass valve 10 Control device 11 Check valve 12 First flow control line 13 Second flow control line 14 Third flow control line 14a Bypass line 15 Fourth flow control line 15a Bypass line 16 Discharge line 17 Rod side meter-in valve 18 Head Side meter-in valve 19 Rod side meter-out valve 20 Regenerative hydraulic motor 20a Displacement capacity control means 21 Generator 22 Check valve 23 Control lever 24 Motor 25 Fuel cell device 26 Electrolyzer 27 Hydrogen storage device 28 Fuel cell 29 Power supply path 30 Return Route 31 reformer 32 capacitor 33 battery 34 inverter 35 Engine 36 oxygen passage 37 hydrogen passage 39 the air supply port 51 check valve A connecting portion B connecting portion C connecting portion D connecting portion W weight loading

Claims (10)

An energy regeneration system for a work machine,
A hydraulic actuator adapted to operate by supplying or discharging fluid;
A variable capacity regenerative fluid pressure motor, which is disposed in a discharge passage for fluid discharged from a fluid pressure actuator, and controls the displacement of the variable capacity regenerative fluid pressure motor to control the discharge fluid from the fluid pressure actuator. A variable capacity regenerative fluid pressure motor adapted to control the flow rate of
An energy regeneration system for a work machine, comprising: an energy regeneration device that at least partially regenerates the energy of discharged fluid as electric energy by rotating a regeneration fluid pressure motor.   The energy regeneration system for a work machine according to claim 1, wherein the displacement of the regenerative fluid pressure motor is controlled such that the flow rate of the discharge fluid from the fluid pressure actuator changes from zero to a predetermined maximum value.   The energy regeneration system for a work machine according to claim 2, wherein the flow rate of the supply fluid to the fluid pressure actuator is controlled by a supply flow rate control valve.   4. The operation according to claim 3, wherein the fluid pressure actuator is a single rod fluid pressure cylinder, and the regenerative fluid pressure motor is provided in a discharge passage for fluid discharged from a head side chamber of the fluid pressure cylinder. Energy regeneration system for machines.   5. The work machine according to claim 4, further comprising: a control device that receives an input signal from an operation instrument of the fluid pressure actuator and outputs a control command to a displacement control means for the regenerative fluid pressure motor based on the input signal. Energy regeneration system. A pump adapted to supply pressurized fluid to the fluid pressure actuator;
And a motor operably connected to the pump,
The energy regeneration system for work machines according to claim 5, wherein the electric energy obtained by the energy regeneration device is used as a power source for a motor.   The energy regeneration system for work machines according to claim 6, wherein the motor is used as an auxiliary power source for the pump. Energy regeneration device
Electric power generating means for generating electric power through rotation driving of the regenerative fluid pressure motor;
Power storage means for storing power generated by the power generation means;
The energy regeneration system for work machines according to claim 7, further comprising: an inverter that converts electric power stored in the electric storage means into AC electric power. A meter-out valve disposed at least partially in a discharge line of the discharge flow path; and the control device is control-connected to the variable displacement hydraulic motor and the meter-out valve;
The control device is configured to output a zero displacement command to the displacement control means of the variable displacement hydraulic motor in response to an actuator extension command from an operator input device,
The control device is configured to output a non-zero displacement command to the displacement control means of the variable displacement hydraulic motor in response to an actuator contraction command from the operator input device. The energy regeneration system described in 1.   The engine further comprises: an engine; a hydraulic pump operably connected to the engine; and an electric motor separated from the variable displacement hydraulic motor and operably connected to each of the energy recovery device and the hydraulic pump. The energy regeneration system described in 1.

Images