Fuel Efficient Crane System
AssigneeTMEIC Corporation
InventorsPaul S. Bixel, Marcelo Andres Lara
Life of this patent
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Abstract
A system and method for efficiently regulating the fuel consumption of a variable speed combustion engine used to control loads such as a hoist motor in a mobile gantry crane based on load motor speed commands issued by a crane operator. The system and method can rely on a programmable logic controller to issue engine fuel commands to regulate engine speed based on interpolations derived from data representing the relationship between load motor voltage and engine speed and data representing the relationship between engine speed and engine power capacity. The method may also be used in modified form by combustion engines which need digital fixed speed commands.
Claims16
A system for use with an operator supervised crane enabling a variable speed combustion engine to produce varying AC voltage to control at least one load comprising:
- a generator coupled to and driven directly by the engine having a speed corresponding to the speed of the engine and producing a variable AC voltage output;
- a first AC bus line connected on one end to the output of said generator;
- a diode converter producing a variable DC voltage having an input and an output wherein the input thereof is connected to the opposing end of said first AC bus line;
- a DC bus line connected on one end to the output of said diode converter;
- at least one inverter each having at least one input and an output wherein an input of each one thereof is connected to said DC bus line;
- at least one second AC bus line each of which is separately connected on one end to the output of a separate one of said at least one inverter;
- and
- at least one motor load each of which is connected to the opposite end of one of said separate second AC bus lines.
A method for controlling the speed of a variable speed combustion engine coupled to a generator providing power to a motor load on a crane wherein data representing the relationships between motor voltages and engine speeds and between engine speeds and engine power capacities is known, comprising:
- selecting a motor load speed;
- generating a first engine speed command based on interpolation of data representing the relationship between motor voltages of the motor load and engine speeds;
- determining the power required by the motor load;
- further generating a second engine speed command based on interpolation of data representing the relationship between engine speeds and engine power capacities;
- choosing the higher of the first engine speed command and the second engine speed command;
- and
- issuing an engine fuel command to the engine based on the chosen engine speed command.
A method for controlling the speed of a variable speed combustion engine coupled to a generator providing power to at least one motor load on a crane wherein data representing the relationships between motor voltages and engine speeds and between engine speeds and engine power capacities is known and a speed change has been requested for at least one of the motor loads, comprising:
- selecting motor speeds for each of the at least one motor load to satisfy the speed change request;
- generating an engine speed command for each of the at least one motor load based on interpolation of data representing the relationship between motor voltages of the motor load and engine speeds;
- clamping each engine speed command to within a predetermined range;
- designating the highest of the engine speed commands as the first engine speed command;
- determining the total power required by all of the at least one motor load;
- further generating a second engine speed command based on interpolation of data representing the relationship between engine speeds and engine power capacities;
- choosing the higher of the first engine speed command and the second engine speed command;
- and
- issuing an engine fuel command to the engine based on the chosen engine speed command.
A method for providing a constant or nearly constant AC voltage to an auxiliary load on a crane having a variable speed combustion engine coupled to a generator producing a variable AC voltage onto a first AC bus which is converted into a variable DC voltage on a DC bus by a diode converter, wherein the variable DC voltage is further converted by an inverter into an AC voltage delivered on a second AC bus to the auxiliary load comprising:
- obtaining a signal proportional to the voltage on the DC bus wherein the signal is one selected from the group consisting of a DC bus voltage, an AC voltage, an AC frequency or a generator speed;
- and
- calculating a normalized modulation index to present to the modulator inherent in the inverter.
A method for providing a constant or nearly constant AC voltage to an auxiliary load on a crane having a variable speed combustion engine coupled to a generator producing a variable AC voltage onto a first AC bus which is converted into a variable DC voltage on a DC bus by a diode converter, wherein the variable DC voltage is further converted by an inverter into an AC voltage delivered on a second AC bus to the auxiliary load comprising:
- obtaining a feedback signal representative of the output of the AC voltage of the inverter;
- calculating a modulation index to present to the modulator inherent in the inverter;
- and
- regulating the output voltage of the inverter based on said AC voltage signal.
A method for providing a constant or nearly constant AC voltage to an auxiliary load on a crane system having a variable speed combustion engine coupled to a generator producing a variable AC voltage onto a first AC bus which is converted into a constant DC voltage on a DC bus by a thyristor converter connected to an inverter further connected by means of a second AC bus to the auxiliary load, the crane system having further a DC bus voltage sensor connected to the DC bus, an AC voltage or frequency sensor connected to the first AC bus, an AC line voltage phase locked loop connected to the AC voltage or frequency sensor, a firing angle controller connected to the AC line voltage phase locked loop and a voltage controller connected to the firing angle controller and to the DC voltage bus sensor, comprising:
- detecting the DC bus voltage with a sensor connected to the DC bus;
- feeding back the detected DC bus voltage to the voltage controller;
- comparing the detected DC bus voltage against a reference DC bus voltage figure;
- issuing a DC bus voltage command to the thyristor firing angle controller;
- further detecting either the AC voltage or the frequency of the AC bus with the sensor connected to the first AC bus;
- transmitting the detected AC voltage or frequency to the AC line voltage phase locked loop;
- and
- issuing a firing angle command to the thyristor through the firing angle controller based on a combination of the output from the phase locked loop and the output of the voltage controller.
Dependencies are inferred from the claim text.