Hybrid excavator and method of controlling hybrid excavator

• US 8,768,578 B2
• Filed: 06/08/2010
• Issued: 07/01/2014
• Est. Priority Date: 06/09/2009
• Status: Active Grant

• Current Assignee: Sumitomo Heavy Industries Limited
• Original Assignee: Sumitomo Heavy Industries Limited
• Inventors: Kawashima, Koji, Sugiyama, Yuta
• Primary Examiner(s): Algahaim, Helal A
• Assistant Examiner(s): MOTT, GENNA M
• Application Number:
  US13/376,932
• Publication Number:
  US 20120082536A1
• Time in Patent Office: 1,484 Days
• Field of Search: None
• US Class Current: 701/50
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 10/30 including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: B60W 2300/17 Construction vehicles, e.g. graders, excavators
• CPC Class Codes: B60W 2710/244 Charge state
• CPC Class Codes: B60W 2710/248 Current for loading or unloading
• CPC Class Codes: B60Y 2200/41 Construction vehicles, e.g. graders, excavators
• CPC Class Codes: B60Y 2200/412 Excavators
• CPC Class Codes: B60Y 2200/92 Hybrid vehicles
• CPC Class Codes: B60Y 2400/114 Super-capacities
• CPC Class Codes: B66C 13/28 utilising regenerative braking for controlling descent of heavy loads and having means for preventing rotation of motor in the hoisting direction when load is released
• CPC Class Codes: E02F 9/123 Drives or control devices specially adapted therefor E02F9/125 and E02F9/128 take precedence
• CPC Class Codes: E02F 9/128 Braking systems
• CPC Class Codes: E02F 9/2058 Electric or electro-mechanical or mechanical control devices of vehicle sub-units for vehicles in general B60W
• CPC Class Codes: E02F 9/2075 of the hybrid type for vehicles in general B60W20/00
• CPC Class Codes: E02F 9/2091 Control of energy storage means for electrical energy, e.g. battery or capacitors energy recovery arrangements in hydraulic or pneumatic drives E02F9/2217
• CPC Class Codes: E02F 9/2095 Control of electric, electro-mechanical or mechanical equipment not otherwise provided for, e.g. ventilators, electro-driven fans control of hydraulic driven equipment E02F9/22
• CPC Class Codes: E02F 9/2217 with energy recovery arrangements, e.g. using accumulators, flywheels
• CPC Class Codes: E02F 9/2246 : Control of prime movers, e.g. depending on the hydraulic load of work tools
• CPC Class Codes: H01M 10/44 : Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 : Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H02J 7/00302 : Overcharge protection
• CPC Class Codes: H02J 7/1423 : with multiple batteries
• CPC Class Codes: H02J 7/1492 : by means of controlling devices between the generator output and the battery
• CPC Class Codes: H02J 7/342 : The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging with circuits for polarity protection H02J7/0034
• CPC Class Codes: H02J 7/345 : using capacitors as storage or buffering devices
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries

Abstract

A motor generator control unit controls operation of a motor generator which generates power using a driving force transmitted from an engine. A charge/discharge control unit electrically connects first and second electrical power storage devices and controls charging/discharging of power between the first and second electrical power storage devices in response to an externally supplied control signal. A motor which is electrically connected to the second electrical power storage device is capable of regenerating electric energy and storing the regenerated energy in the second electrical power storage device. A control device supplies a control signal to at least one of the motor generator control unit and the charge/discharge control unit and reduces an electrical power storage target value of at least one of the first and second electrical power storage devices before the motor regenerates energy.

Claims

1. A hybrid excavator including a lower running body, an upper turning body which is turned on the lower running body, a boom having an end rotatably attached to the upper turning body, an arm having an end rotatably attached to the other end of the boom, and a work element rotatably attached to the other end of the arm,

the hybrid excavator comprising:

an engine disposed in the upper turning body to generate a driving force;

a motor generator disposed in the upper turning body to perform an electric power generating operation by the driving force transmitted from the engine;

a motor generator control unit disposed in the upper turning body to control operation of the motor generator in response to an externally supplied control signal;

a first electrical power storage device disposed in the upper turning body and being capable of storing electricity;

a second electrical power storage device disposed in the upper turning body, electrically connected to the motor generator control unit and being capable of storing electricity;

a charge/discharge control unit disposed in the upper turning body to electrically connect the first electrical power storage device and the second electrical power storage device together and control a charge/discharge operation between the first electrical power storage device and the second electrical power storage device in response to the externally supplied control signal;

a motor disposed in the upper turning body and electrically connected to the second electrical power storage device, the motor being capable of performing a regeneration operation to generate electric energy from mechanical energy and capable of storing the electric energy generated by the regeneration operation in the second electrical power storage device; and

a control device disposed in the upper turning body to supply a control signal to at least one of the motor generator control unit and the charge/discharge control unit,

wherein the control device is arranged to reduce an electrical power storage target value of at least one of the first electrical power storage device and the second electrical power storage device before the regeneration operation is performed by the motor.

2. The hybrid excavator according to claim 1,

wherein, during a period in which the regeneration operation is performed by the motor, the control device sets the electrical power storage target value that is reduced by the control device before the regeneration operation is performed by the motor to a value larger than a previously set value before the regeneration operation is performed.

3. The hybrid excavator according to claim 1, wherein, during a period in which a motor-assisted operation is performed by the motor generator before the regeneration operation is performed by the motor, the control device sets the electrical power storage target value to a value smaller than a previously set value before the motor-assisted operation is performed.

4. The hybrid excavator according to claim 1,

wherein, during a period in which a mechanical power generating operation is performed by the motor before the regeneration operation is performed by the motor, the control device sets the electrical power storage target value to a value smaller than a previously set value before the mechanical power generating operation is performed.

5. The hybrid excavator according to claim 1, wherein the motor is a boom regeneration motor and includes an angle detecting part to detect an angle of the boom, and

the control device comprises:

an estimated regeneration energy computing unit to compute an estimated regeneration energy based on the angle of the boom detected by the angle detecting part;

an electrical power storage target value determining unit to determine the electrical power storage target value based on the estimated regeneration energy computed by the estimated regeneration energy computing unit; and

an electrical power storage target value control unit to control at least one of the motor generator control unit and the charge/discharge control unit so that the electrical power storage target value determined by the electrical power storage target value determining unit is set up.

6. The hybrid excavator according to claim 5, wherein the estimated regeneration energy computing unit computes the estimated regeneration energy of the boom based on a potential energy of the boom.

7. The hybrid excavator according to claim 1, wherein the motor is a turning motor and includes a turning speed detecting part to detect a turning speed of the upper turning body, and

the control device comprises:

an estimated regeneration energy computing unit to compute an estimated regeneration energy based on the turning speed detected by the turning speed detecting part;

an electrical power storage target value determining unit to determine the electrical power storage target value based on the estimated regeneration energy computed by the estimated regeneration energy computing unit; and

an electrical power storage target value control unit to control at least one of the motor generator control unit and the charge/discharge control unit, so that the electrical power storage target value determined by the electrical power storage target value determining unit is set up.

8. The hybrid excavator according to claim 7, wherein the estimated regeneration energy computing unit computes the estimated regeneration energy of the upper turning body based on a kinetic energy of the upper turning body.

9. The hybrid excavator according to claim 7, wherein a lifting magnet is provided in the work element, and the estimated regeneration energy computing unit sets the estimated regeneration energy of the lifting magnet to a fixed value when the lifting magnet is in operation.

10. The hybrid excavator according to claim 1, wherein the control device sets a charging ratio of the first electrical power storage device before it is estimated that the regeneration operation will be performed by the motor to 95% or larger.

11. The hybrid excavator according to claim 1,

wherein the control device sets a voltage of the second electrical power storage device before it is estimated that regeneration operation is performed by the motor, to a voltage value larger than a voltage of the first electrical power storage device.

12. A method of controlling a hybrid excavator including:

an engine to generate a driving force;

a motor generator to perform an electric power generating operation by the driving force transmitted from the engine;

a motor generator control unit to control operation of the motor generator in response to an externally supplied control signal;

a first electrical power storage device capable of storing electricity;

a second electrical power storage device electrically connected to the motor generator control unit and being capable of storing electricity;

a charge/discharge control unit electrically connecting the first electrical power storage device and the second electrical power storage device together and controlling a charge/discharge operation between the first electrical power storage device and the second electrical power storage device in response to an externally supplied control signal;

a motor electrically connected to the second electrical power storage device, the motor being capable of performing a regeneration operation to generate electric energy from mechanical energy and capable of storing the electric energy generated by the regeneration operation in the second electrical power storage device; and

a control device to supply a control signal to at least one of the motor generator control unit and the charge/discharge control unit;

the method of controlling the hybrid excavator comprising;

reducing an electrical power storage target value of at least one of the first electrical power storage device and the second electrical power storage device before the regeneration operation is performed by the motor.