CONTROL SYSTEM FOR A HYBRID EXCAVATOR

• US 20130090771A1
• Filed: 06/28/2010
• Published: 04/11/2013
• Est. Priority Date: 06/28/2010
• Status: Active Grant

• Current Assignee: Volvo Construction Equipment AB (Volvo AB)
• Original Assignee: Volvo Construction Equipment AB (Volvo AB)
• Inventors: Lee, Chun-Han, Kim, Jae-Hong
• Granted Patent: US 9,182,312 B2
• Time in Patent Office: Days
• US Class Current: 700/279
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: E02F 9/2025 Particular purposes of control systems not otherwise provided for E02F3/16, E02F3/26, sub-groups of E02F3/43, E02F3/651, sub-groups of E02F3/84, E02F3/907, E02F5/145 take precedence
• 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 9/2246 Control of prime movers, e.g. depending on the hydraulic load of work tools
• CPC Class Codes: F16H 61/468 for achieving a target input torque
• CPC Class Codes: G01M 1/22 and converting vibrations due to imbalance into electric variables

Abstract

The present invention relates to a control system for a hybrid excavator including an engine, a hydraulic pump driven by the engine to drive a hydraulic actuator by hydraulic fluid, a generator driven by the engine to generate electric energy, and an energy storage device charging the electric energy generated by the generator and supplying the electric energy to an electric actuator, the control system comprising: a required torque detection means for detecting a torque that is required to drive the hydraulic pump; a charge amount detection means for detecting a charge rate (or charge amount) of the electric energy storage device; a memory storing a generation degree (or generation amount) in accordance with the torque and the charge rate (or charge amount); and a hybrid control means for controlling the generator in accordance with the torque value detected by the required torque detection means and the generation amount in a memory means that corresponds to the charge rate value (or charge amount) detected by the charge amount detection means. According to the control system, the fuel efficiency is optimized by driving the electric generator attached to the engine based on the required torque of the hydraulic pump and the preset generation amount value corresponding to the SOC (State Of Charge).

Claims

1. A control system for a hybrid excavator including an engine, a hydraulic pump driven by the engine to drive a hydraulic actuator by hydraulic fluid discharged therefrom, an electric generator driven by the engine to generate electric energy, and an electric energy storage device for charging the electric energy generated by the electric generator and supplying the electric energy to an electric actuator, the control system comprising:

a required torque detection means for detecting a torque that is required to drive the hydraulic pump;

a charge amount detection means for detecting a charge rate (or charge amount) of the electric energy storage device;

a memory for storing a degree of electricity generation (or amount of electricity generation) based on the torque and the charge rate (or charge amount); and

a hybrid control means for controlling the electric generator based on the amount of electricity generation stored in the memory, which corresponds to both the torque value detected by the required torque detection means and the charge rate (or charge amount) value detected by the charge amount detection means.

2. The control system for a hybrid excavator according to claim 1, wherein the electric generator attached to and driven by the engine performs a motor function, and operates the hydraulic pump together with the engine.

3. The control system for a hybrid excavator according to claim 1, further comprising a charging means for charging the electric energy storage device by operating the engine in an appropriate torque region of a different revolution that is suitable for electricity generation if the required torque detection means detects a torque that is lower than a predetermined level, which is determined to correspond a standby state in which no work is done.

4. The control system for a hybrid excavator according to claim 1, further comprising an engine revolution adjustment unit for reducing the engine revolution to a low RPM with small fuel consumption if the required torque detection means detects a torque that is lower than a predetermined level, which is determined to correspond to a standby state in which no work is done.

5. The control system for a hybrid excavator according to claim 1, further comprising an electric generator driving unit for driving the electric generator at a level that is higher than a predetermined level if the required torque detection means detects a torque that is lower than a predetermined level, which is determined to correspond to a standby state in which no work is done.

6. The control system for a hybrid excavator according to any one of claims 3 to 5, further comprising a means for identifying movement of an excavator adjustment lever, so that if the adjustment lever is not operated, it is determined that the excavator is in a standby state in which no work is done, and an engine use region is controlled.