Patent Application Titled "Construction Machine Energy Regeneration Apparatus" Published Online (USPTO 20160122980)
By a News Reporter-Staff News Editor at Energy Weekly News -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors KONDO, Akihiro (Nishinomiya-shi, JP); FUJIYAMA, Kazuto (Kobe-shi, JP), filed on August 4, 2014, was made available online on May 12, 2016.
The assignee for this patent application is Kawasaki Jukogyo Kabushiki Kaisha.
Reporters obtained the following quote from the background information supplied by the inventors: "As one example of a conventional hydraulic excavator, there is a hydraulic excavator that causes an electric motor to regenerate electric power when, for example, reducing the speed of a turning unit, stores the regenerative electric power in a capacitor, uses the regenerative electric power stored in the capacitor to operate the electric motor via a controller and an inverter when turning the turning unit, and assists the rotation of a hydraulic motor with the torque of the electric motor (see Patent Literature 1, for example).
"By thus using the regenerative electric power stored in the capacitor to assist the rotation of the hydraulic motor, the fuel consumption can be reduced."
In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "Technical Problem
"However, the above-described conventional hydraulic excavator needs to include the capacitor and the inverter as equipment for storing the regenerative electric power and utilizing the stored regenerative electric power when turning the turning unit. This causes an increase in cost, a high possibility of the occurrence of a failure, and in addition, size and weight increase. Moreover, the above-described conventional hydraulic excavator goes through multiple steps including: converting mechanical energy of the turning unit into electrical energy; temporarily storing the electrical energy; and then converting the electrical energy into mechanical energy again. Therefore, the overall energy regenerative ratio is not very high, which is another problem. Furthermore, the above-described conventional hydraulic excavator is unable to regenerate potential energy when the hydraulic excavator is in a motion different from turning (i.e., boom lowering, arm crowding, or bucket crowding).
"The present invention has been made to solve the above-described problems. An object of the present invention is to provide a construction machine energy regeneration apparatus and a construction machine including the same, which make it possible to eliminate the capacitor and the inverter, thereby reducing the cost to be inexpensive, reducing failures, and reducing the size to suppress an increase in weight.
"Solution to Problem
"A construction machine energy regeneration apparatus according to the present invention is an energy regeneration apparatus of a construction machine, the construction machine including a first operating part and a second operating part, which are driven by a hydraulic fluid, the first operating part including a boom, a turning unit, or a running unit, the second operating part including an arm, a bucket, or an engine-assisting hydraulic motor. The construction machine energy regeneration apparatus includes: a movable weight provided in the construction machine and movable vertically; and a power-transmitting hydraulic circuit, which moves the movable weight upward by utilizing energy that is generated when the boom, the arm, or the bucket moves in a gravitational direction or energy that is generated when a brake is applied to bring the turning unit or the running unit to a stop, and utilizes potential energy of the movable weight as energy for driving the first operating part or the second operating part.
"According to the construction machine energy regeneration apparatus of the present invention, the movable weight can be moved (e.g., swung) upward by utilizing energy that is generated when the boom or the like moves in the gravitational direction or energy that is generated when a brake is applied to bring the turning unit or the like to a stop. This makes it possible to store the potential energy of the boom or the like or the kinetic energy of the turning unit or the like as the potential energy of the movable weight.
"Then, the boom, the turning unit, or the like can be driven by utilizing the potential energy of the movable weight.
"Since the potential energy of the boom or the like or the kinetic energy of the turning unit or the like can be stored as the potential energy of the movable weight and utilized as described above, the fuel consumption of the construction machine can be reduced compared to conventional art.
"The construction machine energy regeneration apparatus according to the present invention may include: a communication passage, through which a circuit of the first operating part or a circuit of the second operating part communicates with a circuit of the movable weight; and a switching valve, which is provided on the communication passage and which switches a flow direction of the hydraulic fluid in the communication passage. The switching valve may be configured to shift to a first position when the boom, the arm, or the bucket moves in the gravitational direction or when a brake is applied to bring the turning unit or the running unit to a stop, such that the hydraulic fluid flows through the communication passage and the switching valve to move the movable weight upward, and the switching valve may be configured to shift to a second position when the movable weight moves in the gravitational direction, such that the hydraulic fluid flows through the communication passage and the switching valve to drive the first operating part or the second operating part.
"According to the above power-transmitting hydraulic circuit, the switching valve, which switches the flow direction of the hydraulic fluid in the communication passage, is provided on the communication passage, through which the circuit of the first operating part or the circuit of the second operating part communicates with the circuit of the movable weight. Therefore, potential energy or kinetic energy of the first operating part or the second operating part can be regenerated, and the regenerative energy can be utilized for driving the first operating part or the second operating part.
"The construction machine energy regeneration apparatus according to the present invention may be configured such that the movable weight and a part of the power-transmitting hydraulic circuit have a function as a counter weight of the construction machine, and such that a total mass of the movable weight and the part of the power-transmitting hydraulic circuit is substantially equal to a mass of a counter weight required by the construction machine.
"By adopting the above configuration, even though the hydraulic excavator includes the energy regeneration apparatus, the total mass of the hydraulic excavator can be made not to exceed the total mass of the hydraulic excavator that does not include the energy regeneration apparatus. This makes it possible to prevent an increase in power for operating the turning unit or the running unit, which is an operating part, as well as an increase in fuel consumption. Consequently, energy can be regenerated and utilized more effectively.
"In the construction machine energy regeneration apparatus according to the present invention, the movable weight may be supported on a predetermined fulcrum and vertically swingable about the fulcrum by operation of a hydraulic cylinder.
"By adopting the above configuration, the following technical advantages are provided. For example, in order to obtain great potential energy of the movable weight, it is necessary to move the movable weight vertically by a great moving distance. For this reason, it is necessary that the stroke of the hydraulic cylinder be great. However, considering the structure of the hydraulic cylinder, it is desirable that the stroke thereof be relatively small so that stable operation of the hydraulic cylinder will be realized. Accordingly, by providing the movable weight such that the movable weight is vertically swingable about the fulcrum, and setting a distance between the fulcrum and a connection where the hydraulic cylinder is connected to the movable weight to be suitably short, the moving distance of the center of gravity of the movable weight in the vertical direction can be made relatively great, and in addition, the stroke of the hydraulic cylinder for vertically swinging the movable weight by a predetermined angle can be set to be relatively small.
"In the construction machine energy regeneration apparatus according to the present invention, the movable weight may be configured to be movable in a linear direction.
"This makes it possible to provide an inexpensive construction machine energy regeneration apparatus with a simple structure and reduced failures.
"In the construction machine energy regeneration apparatus according to the present invention, the movable weight may be supported on a predetermined fulcrum and vertically swingable about the fulcrum by operation of a hydraulic cylinder. The hydraulic cylinder may include a lifting cylinder and an assisting cylinder. A distance between the fulcrum and a connection where the lifting cylinder is connected to the movable weight may be set to be greater than a distance between the fulcrum and a connection where the assisting cylinder is connected to the movable weight. The power-transmitting hydraulic circuit may be configured to operate the lifting cylinder when the boom moves in the gravitational direction or when a brake is applied to bring the turning unit or the running unit to a stop, such that the movable weight swings upward, and the power-transmitting hydraulic circuit may be configured to operate the assisting cylinder when the movable weight swings downward to drive the first operating part or the second operating part.
"By adopting the above configuration, the following technical advantages are provided. As described above, the distance between the fulcrum and the connection where the lifting cylinder is connected to the movable weight is set to be greater than the distance between the fulcrum and the connection where the assisting cylinder is connected to the movable weight. Accordingly, the pressure discharged from the assisting cylinder to lower the movable weight can be made higher than the pressure supplied to the lifting cylinder to raise the movable weight. Therefore, the pressure of the hydraulic fluid for driving the first operating part or the second operating part can be made high, which makes it possible to widen a pressure range within which the potential energy of the movable weight is utilized.
"The construction machine energy regeneration apparatus according to the present invention may include: a solenoid pilot valve, which supplies a pilot pressure liquid to a pilot port of the switching valve; a control valve, which controls a pressure and a flow rate of the hydraulic fluid supplied to the first operating part or the second operating part; a remote control valve, which supplies a pilot pressure liquid to a pilot port of the control valve; pressure sensors, which measure a supply pressure and a discharge pressure of the hydraulic fluid of the first operating part or the second operating part, or measure output pressures of the remote control valve, and generate pressure signals; and a controller, which receives the pressure signals and transmits a command signal to the solenoid pilot valve based on the pressure signals.
"As described above, based on an operation amount of the remote control valve for operating the boom, the turning unit, or the like and the supply pressure and the discharge pressure of the hydraulic fluid of the boom, the turning unit, or the like, the controller performs control of opening the switching valve via the solenoid pilot valve. This makes it possible to efficiently regenerate the potential energy or kinetic energy of the boom, the turning unit, or the like as the potential energy of the movable weight.
"Advantageous Effects of Invention
"The construction machine energy regeneration apparatus according to the present invention is configured to regenerate the potential energy of an operating part or kinetic energy based on inertial force, and utilize the regenerative energy for driving an operating part. This makes it possible to reduce the fuel consumption of the construction machine compared to conventional art.
"Moreover, the construction machine energy regeneration apparatus according to the present invention makes it possible to eliminate, for example, a capacitor and an inverter for regenerating the potential energy of an operating part or kinetic energy based on inertial force, thereby reducing the cost to be inexpensive, reducing failures, and reducing the size to suppress an increase in the weight of the construction machine
BRIEF DESCRIPTION OF DRAWINGS
"FIG. 1 is a side view showing a hydraulic excavator including a construction machine energy regeneration apparatus according to Embodiment 1 of the present invention.
"FIG. 2 is a schematic diagram showing, in an exaggerated manner, a movable weight of the construction machine energy regeneration apparatus of FIG. 1.
"FIG. 3 shows a hydraulic circuit of the hydraulic excavator of FIG. 1.
"FIG. 4 shows a control circuit of a weight switching valve of FIG. 3.
"FIG. 5 shows the state of the hydraulic circuit of the hydraulic excavator of FIG. 3 at the time of boom raising.
"FIG. 6 shows the state of the hydraulic circuit of the hydraulic excavator of FIG. 3 when energy is regenerated at the time of boom lowering.
"FIG. 7 shows the state of the hydraulic circuit of the hydraulic excavator of FIG. 3 when regenerative energy is utilized for arm pushing.
"FIG. 8 shows a hydraulic circuit of a hydraulic excavator according to Embodiment 2 in a state where regenerative energy is utilized for bucket pushing.
"FIG. 9 shows a hydraulic circuit of a hydraulic excavator according to Embodiment 3 in a state where regenerative energy is utilized for operating an engine-assisting hydraulic motor and arm pushing.
"FIG. 10 shows a hydraulic circuit of a hydraulic excavator according to Embodiment 4 in a state where energy is regenerated when a brake is applied to bring a turning unit to a stop.
"FIG. 11 shows the state of the hydraulic circuit of the hydraulic excavator of FIG. 10 when regenerative energy is utilized for arm pushing.
"FIG. 12 is a schematic diagram showing, in an exaggerated manner, a movable weight of a construction machine energy regeneration apparatus according to Embodiment 5.
"FIG. 13 is a schematic diagram showing, in an exaggerated manner, a movable weight of a construction machine energy regeneration apparatus according to Embodiment 6."
For more information, see this patent application: KONDO, Akihiro; FUJIYAMA, Kazuto. Construction Machine Energy Regeneration Apparatus. Filed August 4, 2014 and posted May 12, 2016. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=5280&p=106&f=G&l=50&d=PG01&S1=20160505.PD.&OS=PD/20160505&RS=PD/20160505
Keywords for this news article include: Energy, Electric Power, Kawasaki Jukogyo Kabushiki Kaisha.
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