System for determining positions of a control element of an electrically driven actuator

• US 20040016461A1
• Filed: 02/19/2003
• Published: 01/29/2004
• Est. Priority Date: 07/26/2002
• Status: Active Grant

• Current Assignee: Hydac Electronic GmbH
• Original Assignee: Hydac Electronic GmbH
• Inventors: Qu, Wenmin, Morsch, Joachim, Mannebach, Horst Peter
• Granted Patent: US 6,895,997 B2
• Time in Patent Office: Days
• US Class Current: 137/554
• CPC Class Codes: F02D 2041/2024 the control switching a load after time-on and time-off pulses
• CPC Class Codes: F02D 2041/2058 using information of the actual current value
• CPC Class Codes: F02D 41/20 Output circuits, e.g. for controlling currents in command coils
• CPC Class Codes: G05B 19/19 characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path
• CPC Class Codes: G05B 2219/41224 Shaping a bang-bang input
• CPC Class Codes: H01F 7/1844 Monitoring or fail-safe circuits for relays H01H47/002
• CPC Class Codes: Y10T 137/8242 Electrical

Abstract

System determines the position of a control element of an electrically driven actuator. The actuator may be switched on by a controlled switch when a lower threshold value is reached and may be switched off when an upper threshold value is reached. An on-period and an off-period are determined as a function of the lower threshold value, the upper threshold value, and the electric switching behavior of the actuator depending on the position of the control element. From the on-period and the off-period, the position of the control element are determined from a comparison of the quotient of the on-period or off-period and the sum of the on-period and off-period, and form a comparison of the sum of the on-period and the off-period with corresponding stored reference data. The system includes accompanying circuitry for application of the process, and an accompanying device, in particular a hydraulic valve.

Claims

1. A process for determining positions of a control element of an electrically driven actuator, comprising the steps of:

switching on the actuator by a controlled switch when a lower threshold value is reached;

switching off the actuator by the controlled switch when an upper threshold value is reached;

determining an on-period and an off-period as a function of the lower threshold, the upper threshold and electric switching behavior of the actuator depending on positioning of the control element; and

determining positions of the control element from a comparison of a quotient of the on-period or off-period and a sum of the on-period and off-period and from a comparison of the sum of the on-period and off-period with corresponding stored reference data.

2. A process according to claim 1 wherein

the control element of the actuator is an armature of an electromagnet.

3. A process according to claim 1 wherein

the control element movement actuates a valve.

4. A process according to claim 1 wherein

the lower and upper threshold values are preset.

5. A process according to claim 1 wherein

the upper and lower threshold values are selectable.

6. A process according to claim 1 wherein

the upper and lower threshold values are controlled by a stored program.

7. A process according to claim 4 where

monitoring of reaching of the threshold values, triggering of the switch and comparison with the stored reference data are performed by a microcontroller.

8. A process according to claim 1 wherein

a voltage signal on a resistor connected in series with the actuator is evaluated for monitoring reaching of the threshold values.

9. A process according to claim 1 wherein

a holding current is lowered when the actuator is switched through.

10. A process according to claim 1 wherein

circuit current is increased in relation to a rated current when the actuator is switched.

11. A circuit system for determining positions of a control element of an electrically driven actuator, comprising:

a controlled switch for switching on the actuator upon reaching a lower threshold value and for switching off the actuator upon reaching an upper threshold value;

period means for obtaining an on-period and an off-period as a function of the lower threshold value, the upper threshold value and electric switching behavior of the actuator depending on positioning of the control element; and

measurement engineering acquiring means for acquiring the on-period and the off-period, said acquiring means including an electronic computer unit for determining positions of the control element from a comparison of a quotient of the on-period or off-period and a sum of the on-period and off-period and from a comparison of the sum of the on-period and off-period with corresponding stored reference data.

12. A hydraulic valve, comprising:

an inlet;

an outlet;

a movable valve member regulating fluid flow through said inlet and said outlet;

a control element of an electrically driven actuator coupled to said movable valve member;

a controlled switch for switching on the actuator upon reaching a lower threshold value and for switching off the actuator upon reaching an upper threshold value;

period means for obtaining an on-period and an off-period as a function of the lower threshold value, the upper threshold value and electric switching behavior of the actuator depending on positioning of the control element; and

measurement engineering acquiring means for acquiring the on-period and the off-period, said acquiring means including an electronic computer unit for determining positions of the control element from a comparison of a quotient of the on-period or off-period and a sum of the on-period and off-period and from a comparison of the sum of the on-period and off-period with corresponding stored reference data, said computer unit being an integrated circuit combined with said valve to form a structural unit.

13. A device, comprising:

an electrically driven actuator having a control element;

a controlled switch for switching on the actuator upon reaching a lower threshold value and for switching off the actuator upon reaching an upper threshold value;

period means for obtaining an on-period and an off-period as a function of the lower threshold value, the upper threshold value and electric switching behavior of the actuator depending on positioning of the control element; and

measurement engineering acquiring means for acquiring the on-period and the off-period, said acquiring means including an electronic computer unit for determining positions of the control element from a comparison of a quotient of the on-period or off-period and a sum of the on-period and off-period and from a comparison of the sum of the on-period and off-period with corresponding stored reference data, said computer unit being an integrated circuit combined with the device to form a structural unit.