Method for Actuating an Electromagnetic Valve, and Corresponding Fluid System

Abstract

A method for actuating an electromagnetic valve in a fluid system includes, for a specified first time period, a switching current with a specified first amplitude is applied, the switching current switching the electromagnetic valve from a rest state into a switching state. After the specified first time period expires, a holding current with a specified second amplitude is applied, the holding current holding the electromagnetic valve in the switching state. The first amplitude of the first switching current is greater than the second amplitude of the holding current.

Claims

1. A method for actuating an electromagnetic valve in a fluid system, comprising: applying, for a specified first period of time, a switching current with a specified first amplitude, which switches the electromagnetic valve from a rest state into a switched state; applying a holding current, following an expiry of the specified first period of time, with a specified second amplitude, which holds the electromagnetic valve in the switched state, wherein the first amplitude of the switching current is greater than the second amplitude of the holding current; and specifying the first amplitude of the switching current and the second amplitude of the holding current s a function of at least one piece of temperature information.

2. The method as claimed in claim 1, further comprising: specifying the first period of time of the switching current as a function of at least one piece of temperature information.

3. The method as claimed in claim 1, wherein the at least one piece of temperature information comprises information about a fluid temperature in the fluid system and/or information about an ambient temperature and/or information about a drive unit temperature and/or information about a component temperature.

4. The method as claimed in claim 1, further comprising: specifying each of the first amplitude of the switching current and the second amplitude of the holding current with higher values for low temperatures than for high temperatures.

5. The method as claimed in claim 2, further comprising: specifying the first period of time of the switching current for low temperatures to be longer than for high temperatures.

6. The method as claimed in claim 1, further comprising: increasing rapidly the switching current from an initial value to the first amplitude.

7. The method as claimed in claim 1, further comprising: increasing the switching current in stages from an initial value to the first amplitude.

8. A fluid system comprising: at least one electromagnetic valve; and an analysis and control unit configured to apply, for a specified first period of time a switching current with a specified first amplitude to the at least one electromagnetic valve, which switches the at least one electromagnetic valve from a rest state into a switched state, wherein following an expiry of the specified first period of time, the analysis and control unit is further configured to apply a holding current with a specified second amplitude to the at least one electromagnetic valve, which holds the at least one electromagnetic valve in the switched state, wherein the first amplitude of the switching current is greater than the second amplitude of the holding current, and wherein the analysis and control unit is further configured to specify the first amplitude of the switching current and the second amplitude of the holding current as a function of at least one piece of temperature information.

9. The fluid system as claimed in claim 8, wherein the analysis and control unit is further configured to specify the first period of time of the switching current as a function of the at least one piece of temperature information.

10. The fluid system as claimed in claim 8, further comprising: at least one temperature sensor configured to provide the at least one piece of temperature information, which comprises information about a fluid temperature in the fluid system and/or information about an ambient temperature and/or information about a drive unit temperature and/or information about a component temperature.

11. The method as claimed in claim 1, wherein a computer program is configured to carry out the method.

12. The method as claimed in claim 11, wherein the computer program is stored on a machine-readable memory medium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 shows a schematic sectional representation of a section of an exemplary embodiment of a fluid system according to the invention.

[0021] FIG. 2 shows a schematic characteristic curve diagram with two temperature-dependent current characteristic curves that are produced by an exemplary embodiment of a method according to the invention for actuating an electromagnetic valve of the fluid system according to the invention of FIG. 1.

[0022] FIG. 3 shows a schematic characteristic curve diagram with two further temperature-dependent current characteristic curves that are produced by an exemplary embodiment of a method according to the invention for actuating an electromagnetic valve of the fluid system according to the invention of FIG. 1.

EMBODIMENTS OF THE INVENTION

[0023] As can be seen in FIG. 1, the represented exemplary embodiment of a fluid system according to the invention 1 comprises at least one electromagnetic valve 10 and an analysis and control unit 20. The section of the fluid system 1 that is represented shows by way of example an electromagnetic valve 10 with a magnet assembly 12 and a valve cartridge 14, which in the represented exemplary embodiment is screwed into a fluid block 3 that comprises a plurality of fluid channels 5. Furthermore, in the exemplary embodiment that is represented a temperature sensor 22 is screwed into the fluid block 3 that measures a fluid temperature and provides information about the fluid temperature to the analysis and control unit 20 as at least one piece of temperature information. Furthermore, further temperature sensors and/or vehicle systems that are not represented can be used that provide the analysis and control unit 20 with further temperature information, such as for example information about an ambient temperature and/or information about a drive unit temperature and/or information about a component temperature of the magnet assembly 12 or a driver circuit that produces and outputs the current for actuation of the electromagnetic valve 10.

[0024] As can be further seen from FIGS. 1 through 3, the analysis and control unit 20 applies a switching current I1.sub.SH, I2.sub.SH, I1.sub.ST, I2.sub.ST with a specified first amplitude A.sub.SH, A.sub.ST to the electromagnetic valve 10 for a specified first period of time T.sub.H, T.sub.T. The switching current I1.sub.SH, I2.sub.SH, I1.sub.ST, I2.sub.ST switches the electromagnetic valve 10 from a rest state into a switched state. Following the expiry of the expiry of the specified first period of time T.sub.H, T.sub.T, the analysis and control unit 20 applies a holding current I1.sub.HH, I2.sub.HH, I1.sub.HT, I2.sub.HT with a specified second amplitude A.sub.HH, A.sub.HT to the electromagnetic valve 10. The holding current I1.sub.HH, I2.sub.HH, I1.sub.HT, I2.sub.HT holds the electromagnetic valve 10 in the switched state. As can further be seen from FIGS. 2 and 3, the first amplitude A.sub.SH, A.sub.ST of the switching current I1.sub.SH, I2.sub.SH, I1.sub.ST, I2.sub.ST is greater than the second amplitude A.sub.HH, A.sub.HT of the holding current I1.sub.HH, I2.sub.HH, I1.sub.HT, I2.sub.HT. The analysis and control unit 20 specifies the first amplitude A.sub.SH, A.sub.ST of the switching current I1.sub.SH, I2.sub.SH, I1.sub.ST, I2.sub.ST and the second amplitude A.sub.HH, A.sub.HT of the holding current I1.sub.HH, I2.sub.HH, I1.sub.HT, I2.sub.HT as a function of at least one piece of temperature information.

[0025] As can further be seen from FIGS. 2 and 3, the analysis and control unit 20 in the exemplary embodiment that is represented also specifies the first period of time T.sub.H, T.sub.T of the switching current I1.sub.SH, I2.sub.SH, I1.sub.ST, I2.sub.ST as a function of the at least one piece of temperature information.

[0026] The fluid system 1 can for example be embodied as an ABS/TCS/ESP system, wherein the electromagnetic valve 10 can in particular be embodied as a normally closed high-pressure switching valve. The electromagnetic valve 10 is used as a technical component to control the inlet or outlet of gases or liquids or to control or to regulate the direction of flow. Typically, a normally closed valve is actuated to open briefly with the high switching current I1.sub.SH, I2.sub.SH, I1.sub.ST, I2.sub.ST. If the valve is open, the switching current I1.sub.SH, I2.sub.SH, I1.sub.ST, I2.sub.ST can be reduced to the holding current I1.sub.HH, I2.sub.HH, I1.sub.HT, I2.sub.HT because of the smaller residual air gap. With the known actuation methods, two different types of actuation are represented depending on the dynamic requirement. For dynamic actuation, the switching current I1.sub.SH, I1.sub.ST is rapidly increased, for normal actuation the switching current 12.sub.SH, 12.sub.ST is increased in stages. The amplitude of the switching current I1.sub.SH, I2.sub.SH, I1.sub.ST, I2.sub.ST is the same in both cases.

[0027] As can further be seen from FIG. 2, at high temperatures according to the represented solid first current characteristic curve KH1, for a specified first period of time T.sub.H, a first switching current I1.sub.SH is applied rapidly with a specified first amplitude A.sub.SH, which rapidly switches the electromagnetic valve 10 from a rest state, which corresponds in the represented exemplary embodiment to a current value of 0 A, into a switched state, which corresponds to the first amplitude A.sub.SH of the switching current I1.sub.SH. Following the expiry of the specified first period of time T.sub.H, a first holding current I1.sub.HH with a specified second amplitude A.sub.HH is applied, which holds the electromagnetic valve 10 in the switched state. As can further be seen from FIG. 2, the first amplitude A.sub.SH of the first switching current I1.sub.SH is greater than the second amplitude A.sub.HH of the first holding current Il.sub.HH.

[0028] As can further be seen from FIG. 2, at low temperatures according to the represented dotted second current characteristic curve KT1, for a specified first period of time T.sub.T, which in the represented exemplary embodiment is longer than the first period of time T.sub.H at high temperatures, a first switching current Il.sub.ST is applied rapidly with a specified first amplitude A.sub.ST, which is greater than the first amplitude A.sub.SH at high temperatures. Owing to the higher first switching current I1.sub.ST, the electromagnetic valve 10 is also switched rapidly at low temperatures from the rest state into the switched state, which corresponds to the first amplitude A.sub.ST of the first switching current I1.sub.ST at low temperatures. Following the expiry of the specified longer first period of time T.sub.T, a first holding current I1.sub.HT is applied with a specified second amplitude A.sub.HT, which is greater than the second amplitude A.sub.ST at high temperatures. Owing to the higher first holding current I1.sub.HT, the electromagnetic valve 10 is also held in the switched state at low temperatures. As can further be seen from FIG. 2, the first amplitude A.sub.ST of the first switching current I1.sub.ST is also greater than the second amplitude A.sub.HT of the first holding current I1.sub.HT at lower temperatures.

[0029] As can further be seen from FIG. 3, at high temperatures according to the represented solid second current characteristic curve KH2, a second switching current I2.sub.SH with a specified first amplitude A.sub.SH is applied to the electromagnetic valve 10 for a specified first period of time T.sub.H. In contrast to the current characteristic curves KH1, KT1 of FIG. 2, which rapidly rise from an initial current value of 0 A to the first amplitude A.sub.SH of the switching current I1.sub.SH, the current characteristic curves KH2, KT2 of FIG. 3 rise in stages from the initial current value of 0 A to the first amplitude A.sub.SH of the switching current I1.sub.SH, wherein three intermediate stages are provided in the represented exemplary embodiment. As a result, the electromagnetic valve 10 is switched more slowly from the rest state, which corresponds to a current value of 0 A in the represented exemplary embodiment, into a switched state, which corresponds to the first amplitude A.sub.SH of the second switching current I2.sub.SH. Following the expiry of the specified first period of time T.sub.H, a second holding current I2.sub.HH with a specified second amplitude A.sub.HH is applied, which holds the electromagnetic valve 10 in the switched state. As can further be seen from FIG. 3, the first amplitude A.sub.SH of the second switching current I2.sub.SH is greater than the second amplitude A.sub.HH of the second holding current I2.sub.HH.

[0030] As can further be seen from FIG. 3, similarly to FIG. 2 at low temperatures according to the represented dotted second current characteristic curve KT2, a second switching current I2.sub.ST with a specified first amplitude A.sub.ST, which is greater than the first amplitude A.sub.SH at high temperatures, is applied for a specified first period of time T.sub.T, which in the represented exemplary embodiment is longer than the first period of time T.sub.H at high temperatures. Owing to the higher second switching current I2.sub.ST, the electromagnetic valve 10 is also switched at low temperatures from the rest state into the switched state, which corresponds to the first amplitude A.sub.ST of the second switching current I2.sub.ST at low temperatures. Following the expiry of the specified longer first period of time T.sub.T, a second holding current I2.sub.HT is applied with a specified second amplitude A.sub.HT, which is greater than the second amplitude A.sub.ST at high temperatures. Owing to the higher second holding current I2.sub.HT, the electromagnetic valve 10 is also held in the switched state at low temperatures. As can further be seen from FIG. 3, the first amplitude A.sub.ST of the second switching current I2.sub.ST is also greater at lower temperatures than the second amplitude A.sub.HT of the second holding current I2.sub.HT.

[0031] Thus, in the case of the described exemplary embodiments, the first amplitude A.sub.SH, A.sub.ST of the switching current I1.sub.SH, I2.sub.SH, I1.sub.ST, I2.sub.ST and the second amplitude A.sub.HH, A.sub.HT of the holding current I1.sub.HH, I2.sub.HH, I1.sub.HT, I2.sub.HT are specified as a function of at least one piece of temperature information. Furthermore, with the described exemplary embodiments the first period of time T.sub.H, T.sub.T of the switching current I1.sub.SH, I2.sub.SH, I1.sub.ST, I2.sub.ST is specified as a function of at least one piece of temperature information. The at least one piece of temperature information comprises for example information about a fluid temperature in the fluid system 1 and/or information about an ambient temperature and/or information about a drive unit temperature and/or information about a component temperature.

[0032] In the case of the represented exemplary embodiment, two temperature limit values are specified for distinguishing between low and high energization, which can either be determined or measured by means of computer models, resistance measurements or temperature sensors. Of course, more than the two temperature limit values can also be distinguished between in order to achieve a finer graduation. By using a plurality of temperature ranges, advantageously a yet more optimal energization of the electromagnetic valve 10 can be achieved, i.e. so that the amplitude of the switching current A.sub.SH, A.sub.ST and the holding current amplitude A.sub.HH, A.sub.AT is selected to be just large enough as is required for switching and holding the electromagnetic valve 10. If the temperature detection is very accurate, the current specifications can even be interpolated across temperature-dependent current reference points.

[0033] Embodiments of the present invention provide a method for actuating an electromagnetic valve in a fluid system, which advantageously enables the valve function over the entire temperature range by means of suitable actuation or energization without adversely affecting the service life of the components. The core of the invention is a temperature-dependent electrical current profile for switching and holding the valve.