Method and apparatus for recovering inertial energy
First Claim
1. A hydraulic system adapted to recover inertial energy, the hydraulic system comprising:
- a pump;
a variable displacement pump/motor having an input/output shaft adapted for connection to a load;
an accumulator having a charging state and a fully charged state;
at least one pressure relief valve having pressure relief settings, the at least one pressure relief valve being adapted to limit a differential pressure across the variable displacement pump/motor when a set pressure is exceeded;
the variable displacement pump/motor being operable in;
a) a first mode where the variable displacement pump/motor is driven by the pump to rotate the input/output shaft and the load;
b) a second mode where the variable displacement pump/motor uses inertial energy from a deceleration of the load to charge the accumulator;
c) a third mode where the variable displacement pump/motor is driven by the accumulator to rotate the input/output shaft and the load; and
d) a fourth mode where the variable displacement pump/motor dumps inertial energy from a deceleration of the load on the at least one pressure relief valve when the accumulator is in the fully charged state;
a controller for controlling operation of the pump and the variable displacement pump/motor, the controller controlling the variable displacement pump/motor to control a torque transferred through the input/output shaft of the variable displacement pump/motor;
an operator interface for inputting a torque control signal to the controller for controlling a direction of rotation of the input/output shaft and for controlling a speed of rotation of the input/output shaft; and
memory storing a control model including a three-dimensional control map that defines a relationship between a value of the torque control signal, a sensed rotational speed of the input/output shaft of the variable displacement pump/motor, and a torque command that establishes an amount of torque to be transferred through the input/output shaft of the variable displacement pump/motor, the controller using the control model to determine the amount of torque to be transferred through the input/output shaft, the three-dimensional control map including a three-dimensional control map surface defined along first, second and third axes that are perpendicular to one another, the first axis corresponding to the torque command, the second axis corresponding to the torque control signal and the third axis corresponding to the sensed rotational speed of the input/output shaft; and
wherein the pressure relief settings of the at least one pressure relief valve define a top horizontal plane of the control map surface and a bottom horizontal plane of the control map surface, wherein the top horizontal plane corresponds to a torque command establishing a maximum clockwise torque, and wherein the bottom horizontal plane corresponds to a torque command establishing a maximum counterclockwise torque.
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Accused Products
Abstract
A hydraulic system adapted to recover inertial energy is disclosed. The hydraulic system includes a pump, a variable displacement pump/motor having an input/output shaft, an accumulator, and a valve arrangement. The valve arrangement is operable in: a) a first mode where the variable displacement pump/motor is driven by the pump to rotate the input/output shaft and the load; b) a second mode where the variable displacement pump/motor uses inertial energy from a deceleration of the load to charge the accumulator; and c) a third mode where the variable displacement pump/motor is driven by the accumulator to rotate the input/output shaft and the load. The hydraulic system also includes a controller for controlling operation of the pump, the variable displacement pump/motor and the valve arrangement.
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Citations
24 Claims
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1. A hydraulic system adapted to recover inertial energy, the hydraulic system comprising:
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a pump; a variable displacement pump/motor having an input/output shaft adapted for connection to a load; an accumulator having a charging state and a fully charged state; at least one pressure relief valve having pressure relief settings, the at least one pressure relief valve being adapted to limit a differential pressure across the variable displacement pump/motor when a set pressure is exceeded; the variable displacement pump/motor being operable in;
a) a first mode where the variable displacement pump/motor is driven by the pump to rotate the input/output shaft and the load;
b) a second mode where the variable displacement pump/motor uses inertial energy from a deceleration of the load to charge the accumulator;
c) a third mode where the variable displacement pump/motor is driven by the accumulator to rotate the input/output shaft and the load; and
d) a fourth mode where the variable displacement pump/motor dumps inertial energy from a deceleration of the load on the at least one pressure relief valve when the accumulator is in the fully charged state;a controller for controlling operation of the pump and the variable displacement pump/motor, the controller controlling the variable displacement pump/motor to control a torque transferred through the input/output shaft of the variable displacement pump/motor; an operator interface for inputting a torque control signal to the controller for controlling a direction of rotation of the input/output shaft and for controlling a speed of rotation of the input/output shaft; and memory storing a control model including a three-dimensional control map that defines a relationship between a value of the torque control signal, a sensed rotational speed of the input/output shaft of the variable displacement pump/motor, and a torque command that establishes an amount of torque to be transferred through the input/output shaft of the variable displacement pump/motor, the controller using the control model to determine the amount of torque to be transferred through the input/output shaft, the three-dimensional control map including a three-dimensional control map surface defined along first, second and third axes that are perpendicular to one another, the first axis corresponding to the torque command, the second axis corresponding to the torque control signal and the third axis corresponding to the sensed rotational speed of the input/output shaft; and wherein the pressure relief settings of the at least one pressure relief valve define a top horizontal plane of the control map surface and a bottom horizontal plane of the control map surface, wherein the top horizontal plane corresponds to a torque command establishing a maximum clockwise torque, and wherein the bottom horizontal plane corresponds to a torque command establishing a maximum counterclockwise torque. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A hydraulic swing drive for use on an excavating machine, the hydraulic swing drive urging acceleration and deceleration on an excavating structure of the excavating machine, the hydraulic swing drive comprising:
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a hydraulic pump producing a pump pressure of hydraulic fluid in a pump supply line; an accumulator with hydraulic fluid under an accumulator pressure, the accumulator in fluid communication with an accumulator line, the accumulator having a charging state and a fully charged state; a tank with hydraulic fluid in fluid communication with a tank line; a variable displacement pump/motor selectively urging the acceleration and the deceleration on the excavating structure, the variable displacement pump/motor in fluid communication with a first line and a second line of the variable displacement pump/motor, the variable displacement pump/motor including a swash plate; and a valve arrangement selectively connecting the accumulator line with the first line of the variable displacement pump/motor and selectively connecting the tank line with the second line of the variable displacement pump/motor when the accumulator pressure is greater than a threshold pressure and the acceleration of the excavating structure is requested, the valve arrangement selectively connecting the pump supply line with the first line of the variable displacement pump/motor and selectively connecting the tank line with the second line of the variable displacement pump/motor when the accumulator pressure is less than or equal to the threshold pressure and the acceleration of the excavating structure is requested, and the valve arrangement selectively connecting the accumulator line with the second line of the variable displacement pump/motor and selectively connecting the tank line with the first line of the variable displacement pump/motor when the deceleration of the excavating structure is requested and accumulator charging is desired; the swing drive being operable in a first state in which a controller controls a position of the swash plate to selectively increase and decrease a rate of deceleration of the excavation structure without throttling, and the swing drive also being operable in a second state in which the variable displacement pump/motor dumps inertial energy from a deceleration of the excavating structure on at least one pressure relief valve when the accumulator is in the fully charged state. - View Dependent Claims (17, 18)
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19. A hydraulic system adapted to recover inertial energy, the hydraulic system comprising:
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a pump; a variable displacement pump/motor having an input/output shaft adapted for connection to a load; an accumulator; at least one pressure relief valve having pressure relief settings; a valve arrangement operable in;
a) a first mode where the variable displacement pump/motor is driven by the pump to rotate the input/output shaft and the load;
b) a second mode where the variable displacement pump/motor uses inertial energy from a deceleration of the load to charge the accumulator; and
c) a third mode where the variable displacement pump/motor is driven by the accumulator to rotate the input/output shaft and the load;a controller for controlling operation of the pump, the variable displacement pump/motor and the valve arrangement, the controller controlling the variable displacement pump/motor to control a torque transferred through the input/output shaft of the variable displacement pump/motor; an operator interface for inputting a torque control signal to the controller for controlling a direction of rotation of the input/output shaft and for controlling a speed of rotation of the input/output shaft, wherein when the torque control signal corresponds to a deceleration command, the controller shifts the valve arrangement to the second mode, and wherein the variable displacement pump/motor provides a pumping and braking function when the valve arrangement is in the second mode; and memory storing a control model including a three-dimensional control map that defines a relationship between a value of the torque control signal, a sensed rotational speed of the input/output shaft of the variable displacement pump/motor, and a torque command that establishes an amount of torque to be transferred through the variable displacement pump/motor, the controller using the control model to determine the amount of torque to be transferred through the input/output shaft, the three-dimensional control map including a three-dimensional control map surface defined along first, second and third axes that are perpendicular to one another, the first axis corresponding to the torque command, the second axis corresponding to the torque control signal and the third axis corresponding to the sensed rotational speed of the input/output shaft; wherein the pressure relief settings of the at least one pressure relief valve define a top horizontal plane of the control map surface and a bottom horizontal plane of the control map surface, wherein the top horizontal plane corresponds to a torque command establishing a maximum clockwise torque, and wherein the bottom horizontal plane corresponds to a torque command establishing a maximum counterclockwise torque; and wherein the valve arrangement includes a three-position directional flow control valve and a return flow control valve, wherein in the first mode the directional flow control valve places an outlet side of the pump in fluid communication with a first side of the variable displacement pump/motor and the return flow control valve places a second side of the variable displacement pump/motor in fluid communication with a tank, wherein in the second mode the directional flow control valve blocks fluid communication between the pump and the first side of the variable displacement pump/motor and the return flow control valve blocks fluid communication between the second side of the variable displacement pump/motor and the tank, and wherein in the third mode the directional flow control valve places the accumulator in fluid communication with the first side of the variable displacement pump/motor and the return flow control valve places the second side of the variable displacement pump/motor in fluid communication with the tank. - View Dependent Claims (20, 21, 22)
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23. A hydraulic system adapted to recover inertial energy, the hydraulic system comprising:
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a variable displacement pump/motor having an input/output shaft adapted for connection to a load; a controller for controlling the variable displacement pump/motor, the controller controlling the variable displacement pump/motor to control a torque transferred through the input/output shaft of the variable displacement pump/motor; memory storing a control model including a three-dimensional control map that defines a relationship between a value of the torque control signal, a sensed rotational speed of the input/output shaft of the variable displacement pump/motor, and a torque command that establishes an amount of torque to be transferred through the variable displacement pump/motor, the controller using the control model to determine the amount of torque to be transferred through the input/output shaft, the three-dimensional control map including a three-dimensional control map surface defined along first, second and third axes that are perpendicular to one another, the first axis corresponding to the torque command, the second axis corresponding to the torque control signal and the third axis corresponding to the sensed rotational speed of the input/output shaft; at least one pressure relief valve, the at least one pressure relief valve being adapted to limit a differential pressure across the variable displacement pump/motor when a set pressure is exceeded; and an accumulator, the accumulator having a charging state and a fully charged state; wherein a deceleration of the load charges the accumulator when the accumulator is in the charging state; and wherein the variable displacement pump/motor is configured to dump inertial energy from a deceleration of the load on the at least one pressure relief valve when the accumulator is in the fully charged state. - View Dependent Claims (24)
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Specification