HYBRID CONSTRUCTION MACHINE
First Claim
1. A hybrid construction machine comprising:
- a variable displacement hydraulic pump which discharges hydraulic oil for a hydraulic actuator;
an engine which drives the hydraulic pump;
an electric motor which is driven by the engine to charge generated electric power into an electric storage device and which is driven by the electric power charged in the electric storage device so as to assist the engine to drive the hydraulic pump; and
a controller which controls driving of the hydraulic pump, the engine and the electric motor;
characterized in that;
the controller includes an engine power calculating unit which calculates power generated by the engine, a first rotation speed calculating unit which calculates a rotation speed of the engine to minimize fuel required for generating the engine power, a second rotation speed calculating unit which determines a lower limit of a target rotation speed of the engine, a target rotation speed calculating unit which selects a larger one of a first rotation speed outputted from the first rotation speed calculating unit and a second rotation speed outputted from the second rotation speed calculating unit, an engine control unit which controls the engine so as to make a real rotation speed of the engine close to the target rotation speed, a target flow rate calculating unit which calculates a target flow rate of the hydraulic oil discharged from the hydraulic pump, and a hydraulic pump control unit which controls displacement of the hydraulic pump based on the target flow rate and the real rotation speed or the target rotation speed of the engine.
1 Assignment
0 Petitions
Accused Products
Abstract
[Problem] To provide a hybrid construction machine which can provide the same operation feeling as an ordinary construction machine that is not hybrid without changing the discharge flow rate of a hydraulic pump even when the rotation speed of an engine is changed according to power absorbed by the hydraulic pump.
[Solution] A hybrid construction machine is provided with a variable displacement hydraulic pump 1 which supplies hydraulic oil to a hydraulic actuator, an engine 2 which is provided to be able to drive and rotate the hydraulic pump 1, an electric motor 3 which is provided to be able to drive and rotate the hydraulic pump 1, an engine control dial 4, a controller 4 and an operating lever 5. The controller changes the rotation speed of the engine 2 to reduce fuel consumption according to power generated by the engine 2, and changes displacement of the hydraulic pump 1 based on the rotation speed of the engine 2, the dial position of the engine control dial 4 and the amount of operation on the operating lever 5.
29 Citations
12 Claims
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1. A hybrid construction machine comprising:
- a variable displacement hydraulic pump which discharges hydraulic oil for a hydraulic actuator;
an engine which drives the hydraulic pump;
an electric motor which is driven by the engine to charge generated electric power into an electric storage device and which is driven by the electric power charged in the electric storage device so as to assist the engine to drive the hydraulic pump; and
a controller which controls driving of the hydraulic pump, the engine and the electric motor;
characterized in that;the controller includes an engine power calculating unit which calculates power generated by the engine, a first rotation speed calculating unit which calculates a rotation speed of the engine to minimize fuel required for generating the engine power, a second rotation speed calculating unit which determines a lower limit of a target rotation speed of the engine, a target rotation speed calculating unit which selects a larger one of a first rotation speed outputted from the first rotation speed calculating unit and a second rotation speed outputted from the second rotation speed calculating unit, an engine control unit which controls the engine so as to make a real rotation speed of the engine close to the target rotation speed, a target flow rate calculating unit which calculates a target flow rate of the hydraulic oil discharged from the hydraulic pump, and a hydraulic pump control unit which controls displacement of the hydraulic pump based on the target flow rate and the real rotation speed or the target rotation speed of the engine. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10)
- a variable displacement hydraulic pump which discharges hydraulic oil for a hydraulic actuator;
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2-3. -3. (canceled)
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11. A hybrid construction machine comprising:
- a variable displacement hydraulic pump which discharges hydraulic oil for a hydraulic actuator;
an engine which drives the hydraulic pump;
an electric motor which is driven by the engine to charge generated electric power into an electric storage device and which is driven by the electric power charged in the electric storage device so as to assist the engine to drive the hydraulic pump; and
a controller which controls driving of the hydraulic pump, the engine and the electric motor;
characterized in that;a rotation speed of the engine increases when power generated by the engine increases, and the rotation speed of the engine decreases when the power generated by the engine decreases, while displacement of the hydraulic pump increases when an amount of operation on an operating lever increases or when the rotation speed of the engine decreases, and the displacement of the hydraulic pump decreases when the amount of operation on the operating lever decreases or when the rotation speed of the engine increases.
- a variable displacement hydraulic pump which discharges hydraulic oil for a hydraulic actuator;
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12. (canceled)
Specification