Method for controlling an electromagnetic valve, in particular for an automatic transmission of a motor vehicle

• US 20040225429A1
• Filed: 02/06/2004
• Published: 11/11/2004
• Est. Priority Date: 02/06/2003
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Dorfschmid, Jens, Bayha, Wulf-Siegfried, Keim, Norbert, Ott, Christof, Huber, Bernd, Krohn, Martin, Semler, Juergen
• Granted Patent: US 7,260,462 B2
• Time in Patent Office: Days
• US Class Current: 701/51
• CPC Class Codes: F15B 21/082 with different modes
• CPC Class Codes: F16H 2061/0255 Solenoid valve using PWM or duty-cycle control
• CPC Class Codes: F16H 61/0251 Elements specially adapted for electric control units, e.g. valves for converting electrical signals to fluid signals
• CPC Class Codes: H01F 7/1844 Monitoring or fail-safe circuits for relays H01H47/002
• CPC Class Codes: Y10T 137/86493 Multi-way valve unit

Abstract

A method for controlling an electromagnetic valve, in particular for an automatic transmission of a motor vehicle. With known methods, electromagnetic valves are triggered with a pulse-width-modulated signal having a constant clock frequency. The object is to provide a method by which a rapid response characteristic and a high adjustment precision of the electromagnetic valve are made possible. The specific properties of a hydraulic system in which electromagnetic valves are used, in particular the rigidity and damping, are not constant but instead change considerably under different operating states of the hydraulic system and/or with different performance quantities of the electromagnetic valve. These different properties are taken into account through the change in the clock frequency as a function of performance quantities of the electromagnetic valve. The clock frequency may thus be optimally adapted to the properties of the hydraulic system, and a rapid response characteristic and a high adjustment precision are achieved.

Claims

1. A method for controlling an electromagnetic valve, comprising:

triggering a coil of the electromagnetic valve by a control device with a pulse-width-modulated trigger signal; and

altering a clock frequency of the trigger signal by the control device as a function of a performance quantity of the electromagnetic valve.

2. The method as recited in claim 1, wherein:

the method is for an automatic transmission of a motor vehicle.

3. The method as recited in claim 1, wherein:

the clock frequency depends on at least one of a setpoint valve current through the coil and an actual valve current through the coil.

4. The method as recited in claim 3, wherein:

an armature of the electromagnetic valve is movable on the basis of a force generated by the coil, wherein;

an indicated force and thus a position of the armature is a function of at least one of the setpoint valve current and the actual valve current,

the electromagnetic valve has a transfer cross section for influencing at least one of a pressure condition of a working medium and a flow condition of the working medium,

the transfer cross section is variable via the armature,

the setpoint valve current includes a first setpoint valve current and a second setpoint valve current,

the clock frequency at at least one of the first setpoint valve current and the actual valve current is greater than that at at least one of the second setpoint valve current and the actual valve current, and

the transfer cross section at at least one of the first setpoint valve current and the actual valve current is smaller than that at at least one of the second setpoint valve current and the actual valve current.

5. The method as recited in claim 1, wherein:

the clock frequency depends on a temperature of a working medium of the electromagnetic valve.

6. The method as recited in claim 5, wherein:

the clock frequency becomes higher with an increase in a temperature of the working medium.

7. The method as recited in claim 1, wherein:

the clock frequency depends on a level of a power supply voltage of the electromagnetic valve.

8. The method as recited in claim 7, wherein:

the clock frequency becomes higher with an increase in the power supply voltage.

9. The method as recited in claim 1, wherein:

a load terminal of the electromagnetic valve is in operative connection to a load, and

the clock frequency depends on an operating state of the load.

10. The method as recited in one claim 1, further comprising:

superimposing on the trigger signal a heterodyne signal having a smaller heterodyne frequency in comparison with the clock frequency.

11. The method as recited in claim 10, further comprising:

altering at least one of a heterodyne frequency and an amplitude of the heterodyne signal by the control device as a function of the performance quantity.