CONSTRUCTION MACHINE AND METHOD OF CONTROLLING CONSTRUCTION MACHINE

• US 20100031650A1
• Filed: 03/27/2008
• Published: 02/11/2010
• Est. Priority Date: 03/29/2007
• Status: Active Grant

• Current Assignee: Komatsu Ltd.
• Original Assignee: Komatsu Ltd.
• Inventors: Kawaguchi, Tadashi, Inoue, Hiroaki, Morinaga, Jun
• Granted Patent: US 8,214,110 B2
• Time in Patent Office: Days
• US Class Current: 60/459
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 3/06 Limiting the traction current under mechanical overload conditions
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 58/24 for controlling the temperature of batteries
• CPC Class Codes: B60L 58/25 by controlling the electric load
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2510/246 Temperature
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60Y 2200/412 Excavators
• 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: F02D 29/02 peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors

Abstract

The present invention provides a construction machine where overheating of mounted electric devices can be prevented properly with a simple structure and a method of controlling the construction machine. For this purpose, a pump target discharge flow rate of a hydraulic pump is calculated based on an operated amount of an operating unit, a temperature of an electric device mounted on the construction machine is detected, an engine minimum speed, which is a minimum possible speed of an engine in carrying out low-speed matching for matching output of the engine and pump absorbing horsepower of the hydraulic pump to each other in a low-speed region where speed of the engine is lower than set speed, is calculated by using the detected temperature of the electric device, and a maximum value out of a corresponding speed of the pump target discharge flow rate and the engine minimum speed is generated as a candidate for an engine target speed.

Claims

1. A construction machine comprising:

an engine and a generator motor coupled to each other;

a storage device for storing electric power generated by the generator motor and supplying electric power to the generator motor;

a hydraulic pump driven by the engine and the generator motor;

a hydraulic actuator to which pressure oil discharged from the hydraulic pump is supplied;

an operating unit for operating the hydraulic actuator;

a pump target discharge flow rate calculating unit for calculating a pump target discharge flow rate of the hydraulic pump based on an operated amount of the operating unit;

a temperature detecting unit for detecting temperature of an electric device mounted on the construction machine;

a storage unit for storing an engine minimum speed, which is a minimum possible speed of the engine in carrying out low-speed matching for matching output of the engine and pump absorbing horsepower of the hydraulic pump to each other in a low-speed region where a speed of the engine is lower than a set speed, as a function of the temperature of the electric device where the engine minimum speed increases or is a constant value as the temperature increases;

an engine minimum speed calculating unit for calculating the engine minimum speed corresponding to the temperature of the electric device detected by the temperature detecting unit based on the temperature of the electric device and the function stored in the storage unit; and

an engine target speed candidate generating unit for generating a maximum value out of a corresponding speed of the pump target discharge flow rate calculated by the pump target discharge flow rate calculating unit and the engine minimum speed calculated by the engine minimum speed calculating unit as a candidate for an engine target speed.

2. The construction machine according to claim 1, wherein the electric device is the storage device.

3. The construction machine according to claim 1, further comprising a booster for boosting voltage of the storage device to output, wherein the electric device is the booster.

4. The construction machine according to claim 1, further comprising a booster for boosting voltage of the storage device to output, wherein the electric devices are the storage device and the booster, and

the engine minimum speed calculating unit calculates a first engine minimum speed and a second engine minimum speed respectively corresponding to a temperature of the storage device and a temperature of the booster detected by the temperature detecting unit.

5. A method of controlling a construction machine, which includes an engine and a generator motor coupled to each other, a storage device for storing electric power generated by the generator motor and supplying electric power to the generator motor, a hydraulic pump driven by the engine and the generator motor, a hydraulic actuator to which pressure oil discharged from the hydraulic pump is supplied, and an operating unit for operating the hydraulic actuator, the method comprising:

a pump target discharge flow rate calculating step for calculating a pump target discharge flow rate of the hydraulic pump based on an operated amount of the operating unit;

a temperature detecting step for detecting temperature of an electric device mounted on the construction machine;

an engine minimum speed calculating step for calculating an engine minimum speed, which is a minimum possible speed of the engine in carrying out low-speed matching for matching output of the engine and pump absorbing horsepower of the hydraulic pump to each other in a low-speed region where a speed of the engine is lower than a set speed, by using the temperature of the electric device detected in the temperature detecting step; and

an engine target speed candidate generating step for generating a maximum value out of a corresponding speed of the pump target discharge flow rate calculated in the pump target discharge flow rate calculating step and the engine minimum speed calculated in the engine minimum speed calculating step as a candidate for an engine target speed, wherein

the engine minimum speed is a function of the temperature of the electric device where the engine minimum speed increases or is a constant value as the temperature increases.