Construction machine and method of controlling construction machine
First Claim
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.
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Accused Products
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.
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Citations
5 Claims
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1. A construction machine comprising:
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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. - View Dependent Claims (2, 3, 4)
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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:
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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.
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Specification