# US 7,607,336 B2 · Method for determining the individual control voltage of a piezoelectric element > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,607,336 B2 - Document ID: US7607336B2 - Status: Granted - Kind: B2 - Application number: 10/552,395 - Filed: 2004-02-23 - Published: 2007-01-04 - Granted: 2009-10-27 - Earliest claimed: 2003-04-07 - Assignees: Robert Bosch GmbH - Inventors: Kai Sutter; Andreas Rau - Web page: https://patentgrep.com/patent/US7607336B2 ## CPC - F02D 41/2096: {for controlling piezoelectric injectors (drive and control circuit for piezoelectric devices in general H10N30/802)} - H02N 2/06: Drive circuits; Control arrangements {or methods} - F02D 2041/2051: {using voltage control} - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) - H02N: ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR ## Abstract In a method for ascertaining the control voltage of a piezoelectric element, the voltage drop at the piezoelectric element following a charge process is measured and the control voltage of the piezoelectric element is inferred from this voltage drop. ## Claims ### Claim 1 A method for determining a control voltage of a piezoelectric element, comprising: sensing a voltage drop at the piezoelectric element after a charge process, the sensing of the voltage drop including: measuring a first voltage at the piezoelectric element immediately following the charge process; measuring a second voltage at the piezoelectric element immediately prior to a subsequent discharge process; and subtracting the first and second voltages from each other to provide a difference; and determining the control voltage of the piezoelectric element from the difference. ### Claim 2 (depends on 1) The method according to claim 1, wherein the control voltage is obtained from a characteristic curve which represents a relationship between the difference and the control voltage. ### Claim 3 (depends on 2) The method according to claim 2, wherein the relationship provides that, for a rise in the difference, there is a rise in the control voltage. ### Claim 4 A method for ascertaining a control voltage of a piezoelectric element, the method comprising: measuring a first voltage applied at the piezoelectric element following a charge process; measuring a second voltage applied at the piezoelectric element prior to a subsequent discharge process; subtracting the first and second applied voltages from each other to provide a difference; inferring the control voltage of the piezoelectric element from the difference, wherein the control voltage is inferred from a characteristic representing a relation between the difference and the control voltage; and ascertaining the characteristic experimentally on the basis of a large number of measurements at different actuators. ### Claim 5 A method for ascertaining an individual control voltage of a piezoelectric element, the method comprising: measuring a voltage drop at the piezoelectric element following a charge process; increasing the voltage applied at the piezoelectric element during the charge process iteratively until a voltage applied at the piezoelectric element immediately following the charge process does not deviate from a voltage applied at the piezoelectric element immediately prior to a subsequent discharge process; and rating the voltage as an individual voltage requirement, from which the individual control voltage of the piezoelectric element is inferred. ### Claim 6 (depends on 5) The method according to claim 5, wherein the iterative increase of the voltage applied to the piezoelectric element and the measurement are conducted at low pressures of a fluid to be injected. ### Claim 7 (depends on 6) The method according to claim 6, further comprising continuously measuring a voltage characteristic at the piezoelectric element. ### Claim 8 (depends on 5) The method according to claim 5, further comprising continuously measuring a voltage characteristic at the piezoelectric element. ### Claim 9 A method for ascertaining a control voltage of a piezoelectric element, the method comprising: measuring a voltage drop at the piezoelectric element following a charge process; inferring the control voltage of the piezoelectric element from the voltage drop; applying only one voltage to the piezoelectric element; and increasing a charge time iteratively until a voltage applied at the piezoelectric element immediately following the charge process does not deviate from a voltage applied at the piezoelectric element immediately prior to a subsequent discharge process. ### Claim 10 (depends on 9) The method according to claim 9, further comprising continuously measuring a voltage characteristic at the piezoelectric element. ### Claim 11 A method for ascertaining a control voltage of a piezoelectric element, the method comprising: measuring a voltage drop at the piezoelectric element following a charge process; applying only one voltage to the piezoelectric element; and inferring the control voltage of the piezoelectric element by increasing a charge time iteratively until a voltage applied at the piezoelectric element immediately following the charge process does not deviate from a voltage applied at the piezoelectric element immediately prior to a subsequent discharge process. ### Claim 12 (depends on 11) The method according to claim 11, further comprising continuously measuring a voltage characteristic at the piezoelectric element.