# US 11,298,707 B2 · Method and device for monitoring the rotational speed of an element > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,298,707 B2 - Document ID: US11298707B2 - Status: Granted - Kind: B2 - Application number: 16/253,567 - Filed: 2019-01-22 - Published: 2019-07-25 - Granted: 2022-04-12 - Earliest claimed: 2018-01-23 - Assignees: Eppendorf AG - Applicants: Eppendorf AG - Inventors: Uwe Beukert; Thomas Sporn - Web page: https://patentgrep.com/patent/US11298707B2 ## CPC - B04B 9/10: Control of the drive; Speed regulating {(for solid bowl screw centrifuges B04B1/2016)} - B04B 9/02: Electric motor drives {(dynamo-electric machines associated with centrifuges H02K7/16)} - B04B 13/00: Control arrangements specially designed for centrifuges; Program control of centrifuges (control arrangements for feed, charge or discharge B04B11/00) - H02P 6/16: Circuit arrangements for detecting position - B04B 2013/006: {Interface detection or monitoring of separated components} - H02H 7/093: against increase beyond, or decrease below, a predetermined level of rotational speed (centrifugal switches H01H35/10) - B04B: CENTRIFUGES (high-speed drum mills B02C19/11; domestic spin driers D06F; analysing, measuring or monitoring physical or chemical properties of samples during centrifuging, see the relevant subclasses for these procedures, e.g. G01N) - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) ## Abstract A method and a device for monitoring the rotational speed of an element are disclosed. The element may be part of a centrifuge, e.g. a motor, drive shaft, or rotor of a laboratory centrifuge. The rotational speed of the element is not determined directly, but rather clock cycles are counted while the element rotates by a predetermined rotational angle. Exceeding a predetermined rotational speed is determined by comparing a number of counted cycles with a predetermined value. The method and device can be implemented in hardware without requiring a microcontroller with corresponding software, thereby eliminating a need to software certification. ## Claims ### Claim 1 A method for monitoring a rotational speed of an element and detecting when the rotational speed of the element exceeds a predetermined rotational speed, comprising: generating a clock signal with a defined frequency; counting a number of cycles of the clock signal within a period of time during which the element rotates by a predetermined fraction or multiple of one revolution; comparing the counted number of cycles with a predetermined counter value; determining that the rotational speed of the element exceeds the predetermined rotational speed when the counted number of cycles falls below the predetermined counter value; reducing the rotational speed of the element when the counted number of cycles falls below the predetermined counter value; storing, in a results memory, that the rotational speed of the element has exceeded the predetermined rotational speed; and deleting the results memory by a control signal indicating that the element has come to a standstill or has reached a peripheral speed of less than 3 m/s. ### Claim 2 (depends on 1) The method according to claim 1, wherein the predetermined counter value is proportional to a product of the time required for the element to complete one revolution at the predetermined rotational speed and the defined frequency of the clock signal, rounded to a natural number. ### Claim 3 (depends on 1) The method according to claim 1, wherein rotation of the element is sensed electromagnetically by at least one magnet interacting with a magnetic sensor. ### Claim 4 (depends on 1) The method according to claim 1, wherein the element is part of a laboratory centrifuge and wherein the predetermined rotational speed is adapted for the element. ### Claim 5 (depends on 4) The method according to claim 4, wherein the predetermined rotational speed is encoded on and read out from the element, and wherein i) encoding of the predetermined rotational speed is effected by one or more magnets and reading out is effected by a Hall sensor or ii) encoding is effected by an RFID transponder and reading out is effected by an RFID receiver. ### Claim 6 (depends on 1) The method according to claim 1, wherein the rotational speed of the element is reduced to a standstill when the counted number of cycles falls below the predetermined counter value. ### Claim 7 A device for monitoring a rotational speed of an element and detecting when the rotational speed of the element exceeds a predetermined rotational speed, comprising: a clock generator which generates a clock signal with a defined frequency, a revolution detector which senses rotation of the element by a predetermined fraction or multiple of one revolution; a binary counter adapted to count a number of cycles of the clock signal during which the element rotates by the predetermined fraction or multiple of one revolution; a comparator adapted to compare the counted number of cycles with a predetermined counting value; and a results memory configured to store that the rotational speed of the element has exceeded the predetermined rotational speed, the results memory having an input for a control signal indicating that the element has come to a standstill or has reached a peripheral speed of less than 3 m/s, wherein the control signal causes the results memory to be deleted, wherein exceeding of the predetermined rotational speed is detected by the counted number of cycles falling below the predetermined counting value, and wherein the device reduces the rotational speed of the element when the counted number of cycles falls below the predetermined counting value. ### Claim 8 (depends on 7) The device according to claim 7, wherein the clock generator is a quartz-stabilized clock generator and/or wherein a controller for controlling the rotational speed of the element is adapted to reduce the rotational speed of the element if an exceeding of the predetermined rotational speed is detected. ### Claim 9 (depends on 7) The device according to claim 7, wherein the revolution detector is operatively connected to a D flip-flop and thereby adapted to react only to a rising or falling signal edge. ### Claim 10 (depends on 7) The device according to claim 7, wherein the binary counter is adapted to count the number of cycles of the clock signal during which the element rotates by the predetermined fraction or multiple of one revolution and not to count during a subsequent time period during which the element rotates by the predetermined fraction or multiple of one revolution. ### Claim 11 (depends on 7) The device according to claim 7, wherein the binary counter is an 8-bit binary counter. ### Claim 12 (depends on 7) The device according to claim 7, wherein the comparator is as an 8-bit comparator. ### Claim 13 (depends on 7) The device according to claim 7, wherein the binary counter comprises an overflow memory. ### Claim 14 (depends on 13) The device according to claim 13, wherein a sequence controller is provided which resets at least one of the binary counter, the comparator, and the overflow memory. ### Claim 15 (depends on 1) The method as in claim 1, wherein the element is a centrifuge rotor with a centrifuge, the method further comprising: deleting the results memory in response to a signal indicating that a cover of the centrifuge is open. ### Claim 16 (depends on 1) The method as in claim 1, further comprising: transmitting an output signal from the results memory into a motor control. ### Claim 17 (depends on 7) The device according to claim 7, wherein an output signal from the results memory is transmitted into a motor control, and wherein the motor control is configured to reduce the rotational speed of the element to a standstill when the output signal is high. ### Claim 18 A method for preventing excessive rotational speed of a rotor within a centrifuge, comprising: generating a clock signal with a defined frequency; counting a number of cycles of the clock signal within a period of time during which the rotor rotates by a predetermined fraction or multiple of one revolution; comparing the counted number of cycles with a predetermined counter value; determining that the rotational speed of the rotor exceeds the predetermined rotational speed when the counted number of cycles falls below the predetermined counter value; storing, in a results memory, that the rotational speed of the rotor has exceeded the predetermined rotational speed; transmitting a control signal from the results memory to a motor controller while the results memory stores that the rotor has exceeded the predetermined rotational speed; reducing the speed of the rotor to a standstill in response to the control signal; and deleting the results memory by a control signal indicating that a cover of the centrifuge has been opened.