Construction machine

• US 9,593,464 B2
• Filed: 12/20/2013
• Issued: 03/14/2017
• Est. Priority Date: 12/20/2013
• Status: Active Grant

• Current Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: Amano, Hiroaki, Izumi, Shiho, Ishikawa, Kouji, Imura, Shinya, Nishikawa, Shinji, Kaneta, Tomoaki
• Primary Examiner(s): CAMBY, RICHARD M
• Application Number:
  US15/023,829
• Publication Number:
  US 20160312440A1
• Time in Patent Office: 1,180 Days
• US Class Current: 1/1
• CPC Class Codes: B60W 20/15 Control strategies specially adapted for achieving a particular effect
• CPC Class Codes: B60W 2300/17 Construction vehicles, e.g. graders, excavators
• CPC Class Codes: B60W 2510/09 Other types of propulsion units, e.g. fluid motors, or type not specified
• CPC Class Codes: B60W 2510/30 Auxiliary equipments
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2710/09 Other types of propulsion units, e.g. fluid motors, or type not specified
• CPC Class Codes: B60W 30/1886 Controlling power supply to auxiliary devices
• CPC Class Codes: B60Y 2200/412 Excavators
• CPC Class Codes: B60Y 2200/92 Hybrid vehicles
• CPC Class Codes: B60Y 2400/306 Pressure sensors
• CPC Class Codes: E02F 3/32 working downwardly and towards the machine, e.g. with backhoes
• CPC Class Codes: E02F 9/123 Drives or control devices specially adapted therefor E02F9/125 and E02F9/128 take precedence
• CPC Class Codes: E02F 9/2075 of the hybrid type for vehicles in general B60W20/00
• 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 9/2228 including an electronic controller
• CPC Class Codes: E02F 9/2235 including an electronic controller
• CPC Class Codes: E02F 9/2282 Systems using center bypass type changeover valves
• CPC Class Codes: E02F 9/2285 Pilot-operated systems
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: F15B 15/088 : the motor using combined actuation, e.g. electric and fluid actuation
• CPC Class Codes: F15B 2211/20546 : variable capacity
• CPC Class Codes: F15B 2211/6313 : the pressure being a load pressure
• CPC Class Codes: F15B 2211/6336 : representing a state of the output member, e.g. position, speed or acceleration
• CPC Class Codes: F15B 2211/6652 : Control of the pressure source, e.g. control of the swash plate angle
• CPC Class Codes: F15B 2211/6654 : Flow rate control
• CPC Class Codes: F15B 2211/6658 : Control using different modes, e.g. four-quadrant-operation, working mode and transportation mode
• CPC Class Codes: F15B 2211/7058 : Rotary output members
• CPC Class Codes: F15B 2211/76 : Control of force or torque of the output member
• CPC Class Codes: F15B 2211/88 : Control measures for saving energy
• CPC Class Codes: Y10S 903/93 : Conjoint control of different elements

Abstract

A construction machine includes: a swing structure (20); hydraulic and electric motors (25) mechanically coupled to each other; a hydraulic pump (41) that supplies hydraulic fluid to the hydraulic motor; swing control lever (72) that instructs the swing structure to make a swing motion; and a control device (80) that controls at least either a delivery flow rate of the hydraulic pump or an output torque of the electric motor in such a manner that meter-out and meter-in pressures of the hydraulic motor that is run together with the electric motor approach each other when the demanded torque necessary for the swing motion of the swing structure instructed by the swing control lever can be produced by the electric motor alone.

Claims

1. A construction machine comprising:

a swing structure;

a hydraulic motor for driving the swing structure;

an electric motor for driving the swing structure and being mechanically connected to the hydraulic motor;

a hydraulic pump being driven by a prime mover and for supplying hydraulic fluid to the hydraulic motor;

an operating device configured to instruct the swing structure to make a swing motion; and

a control device configured to, when demanded torque necessary for the swing motion of the swing structure instructed by the operating device can be produced by the electric motor alone, control at least either a delivery flow rate of the hydraulic pump or an output torque of the electric motor in such a manner that meter-out and meter-in pressures of the hydraulic motor that is run together with the electric motor approach each other, or in such a manner that the meter-out pressure is larger than the meter-in pressure.

2. The construction machine of claim 1,

wherein the demanded torque is determined based on operation amount of the operating device and the rotation speed of the swing structure.

3. The construction machine of claim 2,

wherein, when the swing structure is accelerating in a fine operation region where the operation amount of the operating device is equal to or less than a reference value, or when the rotation speed of the swing structure is constant regardless of the operation amount of the operating device,

the control device, with maintenance of the delivery rate of the hydraulic pump at a predetermined value, controls the output torque of the electric motor such that the meter-out and meter-in pressures approach each other, or such that the meter-out pressure is larger than the meter-in pressure.

4. The construction machine of claim 2,

wherein, when the swing structure is accelerating in a fine operation region where the operation amount of the operating device is equal to or less than the reference value, or when the rotation speed of the swing structure is constant regardless of the operation amount of the operating device,

the control device, with maintenance of output torque of the electric motor at a predetermined value, controls the delivery rate of the hydraulic motor such that the meter-out and meter-in pressures approach each other, or such that the meter-out pressure is larger than the meter-in pressure.

5. The construction machine according to claim 3,

wherein, when the swing structure is accelerating with the operation amount of the operating device falling within the fine operation region, the control device, with maintenance of the delivery rate of the hydraulic pump at a standby flow rate, controls the output torque of the electric motor such that the meter-out and meter-in pressures approach each other, or such that the meter-out pressure is larger than the meter-in pressure.