Hybrid construction machine

Patent metadata

Field	Value
Publication number	US-9290908-B2
Application number	US-201113640378-A
Country	US
Kind code	B2
Filing date	May 16, 2011
Priority date	May 21, 2010
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

A hybrid construction machine is capable of performing satisfactory operations even when trouble occurs that disables the electric motor from outputting torque. The hybrid construction has both a hydraulic motor and an electric motor driving the swing structure and a controller for switching between a hydraulic/electric hybrid swing mode (using both the hydraulic motor and the electric motor) and a hydraulic-alone swing mode (using only the hydraulic motor). The switching is executed while achieving satisfactory operability and performance in each mode. Normally, an energy saving operation is performed in the hydraulic/electric hybrid swing mode. When the electric amount of an electricity storage device has gone out of a prescribed range or an abnormality has occurred in an electric system (e.g., failure of an inverter), the swing mode is switched to the hydraulic-alone swing mode so that driving with normal braking torque is possible by the hydraulic motor alone.

First claim

The invention claimed is:

1. A hybrid construction machine comprising:
a prime mover;
a hydraulic pump driven by the prime mover;
a swing structure;
an electric motor for driving the swing structure;
a hydraulic motor for driving the swing structure, and the hydraulic motor being driven by the hydraulic pump;
an electricity storage device connected to the electric motor;
a swing control lever device which outputs a command regarding the driving of the swing structure;
a first control device which switches a swing mode regarding the driving of the swing structure between:
a hydraulic/electric hybrid swing mode for driving the swing structure by a total torque of the electric motor and the hydraulic motor by driving both the electric motor and the hydraulic motor when the swing control lever device is operated, and
a hydraulic-alone swing mode for driving the swing structure by a torque of the hydraulic motor alone by driving only the hydraulic motor when the swing control lever device is operated;

a second control device which controls transfer of electric power between the electricity storage device and the electric motor; and
a swing hydraulic system which includes a swing spool for controlling the flow of hydraulic fluid supplied from the hydraulic pump to the hydraulic motor and the flow of the hydraulic fluid returned from the hydraulic motor to a tank,
wherein the swing hydraulic system is switchable between a first mode in which a maximum output torque of the hydraulic motor equals a first torque and a second mode in which the maximum output torque of the hydraulic motor equals a second torque that is higher than the first torque, and
wherein the first control device includes:
a hydraulic/electric hybrid swing control unit which switches the swing hydraulic system to the first mode and which outputs a torque command to the second control device and thereby drives the electric motor when the swing control lever device is operated,
a hydraulic-alone swing control unit which switches the swing hydraulic system to the second mode and stops the output of the torque command to the second control device, and
switching between the hydraulic/electric hybrid swing mode and the hydraulic-alone swing mode by selecting one of the hydraulic/electric hybrid swing control unit and the hydraulic-alone swing control unit.

2. The hybrid construction machine according to claim 1 , wherein:
the first control device drives the swing structure in the hydraulic/electric hybrid swing mode in a normal operation state, and
the first control device automatically switches the swing mode from the hydraulic/electric hybrid swing mode to the hydraulic-alone swing mode when a predetermined type of failure, abnormality or warning state has occurred in an electric system for the driving of the electric motor including the electric motor and the electricity storage device.

3. The hybrid construction machine according to claim 2 , wherein the first control device automatically switches the swing mode from the hydraulic-alone swing mode to the hydraulic/electric hybrid swing mode when the failure, abnormality or warning has been eliminated.

4. The hybrid construction machine according to claim 1 , wherein:
the first control device drives the swing structure in the hydraulic/electric hybrid swing mode when the amount of electricity stored in the electricity storage device is within a prescribed range, and
the first control device automatically switches the swing mode from the hydraulic/electric hybrid swing mode to the hydraulic-alone swing mode when the amount of electricity stored in the electricity storage device has gone out of the prescribed range.

5. The hybrid construction machine according to claim 1 , wherein the first control device executes the switching between the hydraulic/electric hybrid swing mode and the hydraulic-alone swing mode exclusively in a state in which the swing structure is not moving.

6. The hybrid construction machine according to claim 1 , wherein the first control device executes the switching between the hydraulic/electric hybrid swing mode and the hydraulic-alone swing mode exclusively in a state in which the swing structure is not moving and the swing control lever device is not being operated.

7. The hybrid construction machine according to claim 1 , wherein the first control device executes the switching between the hydraulic/electric hybrid swing mode and the hydraulic-alone swing mode exclusively in a state in which there is no movement of the swing structure, no input to the swing control lever device, no movement of the devices other than the swing structure and no input to an operating device for the prescribed devices other than the swing structure.

8. The hybrid construction machine according to claim 1 , wherein:
the hydraulic motor outputs a maximum torque to independently drive the swing structure, and
the electric motor outputs a maximum torque that is lower than the maximum torque of the hydraulic motor.

9. The hybrid construction machine according to claim 1 , wherein:
the first control device charges the electricity storage device with a charging device when the amount of electricity stored in the electricity storage device just after startup of the construction machine is lower than a prescribed electric amount necessary for the operation in the hydraulic/electric hybrid swing mode,
the first control device executes the swing operation in the hydraulic-alone swing mode when the swing control lever device is operated during the charging process, and
the first control device switches the swing mode to the hydraulic/electric hybrid swing mode after the amount of electricity stored in the electricity storage device has reached the prescribed electric amount.

10. The hybrid construction machine according to claim 1 , wherein:
the first control device discharges the electricity storage device when the amount of electricity stored in the electricity storage device just after startup of the construction machine is higher than a prescribed electric amount necessary for the operation in the hydraulic/electric hybrid swing mode,
the first control device executes the swing operation in the hydraulic-alone swing mode when the swing control lever device is operated during the discharging process, and
the first control device switches the swing mode to the hydraulic/electric hybrid swing mode after the amount of electricity stored in the electricity storage device has reached the prescribed electric amount.

11. The hybrid construction machine according to claim 1 , wherein:
the prime mover is an electric motor, and
the prime mover is powered by a AC power supply.

12. The hybrid construction machine according to claim 1 , wherein:
the prime mover is an electric motor, and
the prime mover is powered by the electricity storage device.

13. The hybrid construction machine according to claim 1 , wherein the first control device further executes the hydraulic/electric hybrid swing control unit in a normal operation state and executes the hydraulic-alone swing control unit when a prescribed type of failure, abnormality or warning state has occurred in an electric system including the electric motor, the electricity storage device and the second control device.

14. The hybrid construction machine according to claim 1 , wherein the first control device further executes the hydraulic/electric hybrid swing control unit when the amount of electricity stored in the electricity storage device is within a prescribed range and executes the hydraulic-alone swing control unit when the amount of electricity

Assignees

• Hiroki Takenori
• Edamura Manabu
• Ishida Toshihiko
• Sugiura Manabu
• Satake Hidetoshi
• Ishikawa Kouji
• Ooki Takatoshi
• Nishikawa Shinji
• Hitachi Construction Machinery

Inventors

• Hiroki Takenori
• Edamura Manabu
• Ishida Toshihiko
• Sugiura Manabu
• Satake Hidetoshi
• Ishikawa Kouji
• Ooki Takatoshi
• Nishikawa Shinji

Classifications

• E02F9/2296

  Systems with a variable displacement pump · CPC title

• E02F9/2095

  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 title

• E02F9/226

  Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating · CPC title

• E02F9/207

  of the type electric propulsion units, e.g. electric motors or generators · CPC title

• E02F9/123 Primary

  Drives or control devices specially adapted therefor (E02F9/125 and E02F9/128 take precedence) · CPC title