Roller mill grinding apparatus with regenerative capability
First Claim
Patent Images
1. A roll grinding apparatus comprising:
- a frame;
a first roll and a second roll mounted on the frame and positioned in spaced proximity to each other to grind materials passing through a gap between the rolls;
a first motor configured to rotate the first roll and a second motor configured to rotate the second roll;
a control apparatus in communication with at least the second motor to control operation of the second motor through control of supply of electrical power to and from the second motor, the control apparatus being configured to;
determine a first target speed for the first roll and a second target speed for the second roll;
sense a current speed of the second roll;
compare the current speed of the second roll to the second target speed; and
cause the second motor to rotate the second roll at the second target speed by;
if the current speed of the second roll is lower than the second target speed, increasing an amount of electrical power provided to the second motor to increase the current speed of the second roll; and
if the current speed of the second roll is higher than the second target speed, then;
decreasing an amount of electrical power provided to the second motor such that the second motor discontinues driving rotation of the second roll and the second roll begins to drive rotation of the second motor to cause the second motor to generate electrical power; and
applying the electrical power generated by the second motor to an electrical load to thereby function as a brake on rotation of the second roll and decrease the current speed of the second roll.
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Abstract
A roll grinding apparatus may comprise a frame, first and second rolls rotatably mounted on the frame in proximity to each other to grind materials passing between the rolls, and first and second motors to rotate the first and second rolls respectively. A control apparatus controls operation of at least one of the motors. The control apparatus may be configured to control the speed of the second roll by providing power to the second motor or braking the second motor through regeneration of energy from the second motor.
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Citations
18 Claims
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1. A roll grinding apparatus comprising:
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a frame; a first roll and a second roll mounted on the frame and positioned in spaced proximity to each other to grind materials passing through a gap between the rolls; a first motor configured to rotate the first roll and a second motor configured to rotate the second roll; a control apparatus in communication with at least the second motor to control operation of the second motor through control of supply of electrical power to and from the second motor, the control apparatus being configured to; determine a first target speed for the first roll and a second target speed for the second roll; sense a current speed of the second roll; compare the current speed of the second roll to the second target speed; and cause the second motor to rotate the second roll at the second target speed by; if the current speed of the second roll is lower than the second target speed, increasing an amount of electrical power provided to the second motor to increase the current speed of the second roll; and if the current speed of the second roll is higher than the second target speed, then; decreasing an amount of electrical power provided to the second motor such that the second motor discontinues driving rotation of the second roll and the second roll begins to drive rotation of the second motor to cause the second motor to generate electrical power; and applying the electrical power generated by the second motor to an electrical load to thereby function as a brake on rotation of the second roll and decrease the current speed of the second roll. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of operating a roll grinding apparatus having a frame, a first roll and a second roll rotatably mounted on the frame and positioned in proximity to each other to grind materials passing through a gap spacing between the rolls, a first motor configured to rotate the first roll and a second motor configured to rotate the second roll, and a control apparatus in communication with each of the first and second motors to control operation of the motors through control of supply of electrical power to the motors, the method comprising:
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determining a target speed for each of the first and second rolls; operating the first roll by supplying electrical power to the first motor; determining a current speed of the second roll; comparing the current speed of the second roll to the target speed for the second roll; and adjusting the speed of the second roll by; if the current speed of the second roll is lower than the second target speed, operating the control apparatus in a first mode by increasing an amount of electrical power provided to the second motor to increase the current speed of the second roll; and if the current speed of the second roll is higher than the second target speed, operating the control apparatus in a second mode by; decreasing an amount of electrical power provided to the second motor such that the second motor discontinues driving rotation of the second roll and rotation of the second roll caused by rotation of the first roll in proximity to the second roll drives rotation of the second motor to cause the second motor to generate electrical power; and applying the electrical power generated by the second motor to an electrical load so that the second motor resists rotation of the second roll and decreases the current speed of the second roll. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A roll grinding apparatus comprising:
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a frame; a first roll and a second roll mounted on the frame and positioned in spaced proximity to each other to grind materials passing through a gap between the rolls; a first motor configured to rotate the first roll and a second motor configured to rotate the second roll; a control apparatus in communication with at least the second motors to control operation of the second motor through control of supply of electrical power to and from the second motor, the control apparatus being configured to; determine a first target speed for the first roll and a second target speed for the second roll; determine a current speed of the second roll; compare the current speed of the second roll to the second target speed; and cause the second motor to rotate the second roll at the second target speed by; if the current speed of the second roll is lower than the second target speed, operating the control apparatus in a first mode by increasing an amount of electrical power provided to the second motor to increase the current speed of the second roll; and if the current speed of the second roll is higher than the second target speed, operating the control apparatus in a second mode by; decreasing an amount of electrical power provided to the second motor such that the second motor discontinues driving rotation of the second roll and the second roll begins to drive rotation of the second motor to cause the second motor to generate electrical power; and applying the electrical power generated by the second motor to an electrical load to thereby function as a brake on rotation of the second roll and decrease the current speed of the second roll.
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Specification