Device for controlling a solenoid valve

Abstract

A device for controlling a solenoid valve that controls the through-flow of a medium in a closed-loop manner includes a control procedure implemented by the device. The control procedure is configured at least in regions as a ramp function. The ramp starts with a ramp start current intensity that is less than an opening start current intensity of the valve at which the valve starts to open. The ramp ends with a ramp end current intensity that is greater than an opening end current intensity at which the valve is fully open. The device is configured to one or more of determine and adjust an amount of the ramp start current intensity in dependence upon a pressure. The amount determined and/or adjusted takes into consideration a pressure of the medium against which the solenoid valve opens.

Claims

1. A device for controlling a solenoid valve that controls the through-flow of a medium in a closed-loop manner, comprising: a controller configured to: operate the solenoid valve to open by causing a current to be applied to the solenoid valve, the applied current including, in at least one region, a ramp current, the ramp current (i) starting with a first current intensity that is less than a current intensity at which the valve starts to open and (ii) ending with a second current intensity that is greater than a current intensity at which the valve is fully open; and determine the first current intensity based on a pressure of the medium against which the solenoid valve opens.

2. The device for controlling a solenoid valve according to claim 1, wherein the controller is configured to determine the second current intensity based on the pressure.

3. The device for controlling a solenoid valve according to claim 1, wherein the controller is configured to determine the second current intensity based on a temperature.

4. The device for controlling a solenoid valve according to claim 1, wherein the solenoid valve is a normally closed high pressure switching valve.

5. The device for controlling a solenoid valve according to claim 1, wherein the applied current includes, in at least one region, a dynamic current function.

6. The device for controlling a solenoid valve according to claim 5, wherein the applied current includes, initially, the ramp current and, subsequently, the dynamic current.

7. The device for controlling a solenoid valve according to claim 1, wherein the ramp current of the applied current is a flat-line current ramp.

8. The device for controlling a solenoid valve according to claim 1, wherein the second current intensity is such that, when the second current intensity is achieved, an excess force of the solenoid valve is as small as possible.

9. The device for controlling a solenoid valve according to claim 1, wherein the controller is configured to switch the solenoid valve from the closed state into the open state during the ramp current of the applied current.

10. A hydraulic brake system in a motor vehicle, comprising: a solenoid valve with a magnet assembly that comprises an electric coil configured to be energized via a control procedure implemented by a device, wherein the electric coil in the energized state generates a magnetic force that is dependent upon a current and drives a valve armature of the solenoid valve, wherein the valve armature urges a closing element during a closing movement in a direction of a valve seat and during an opening movement raises said closing element from the valve seat, a controller configured to: operate the solenoid valve to open by causing a current to be applied to the solenoid valve, the applied current including, in at least one region, a ramp current, the ramp current (i) starting with a first current intensity that is less than a current intensity at which the valve starts to open and (ii) ending with a second current intensity that is greater than a current intensity at which the valve is fully open; and determine the first current intensity based on a pressure of the medium against which the solenoid valve opens.

11. The hydraulic brake system according to claim 10 further comprising: a pressure sensor configured to ascertain the pressure of the medium against which the solenoid valve opens.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) It is to be noted that the features that are listed individually in the description may be combined with one another in any manner that is technically expedient and demonstrate further embodiments of the disclosure. Further features and expediency of the disclosure are disclosed in the description of exemplary embodiments with reference to the attached figures.

(2) In the figures:

(3) FIG. 1a illustrates a valve control procedure known from the prior art in accordance with a dynamic function, and

(4) FIG. 1b illustrates a valve control procedure known from the prior art in accordance with a ramp function followed by a dynamic function, and

(5) FIG. 2 illustrates a valve control procedure (section ramp function) that is possible using the device and is in accordance with one embodiment of the disclosure, and

(6) FIG. 3 illustrates a schematic view of the device in accordance with one embodiment of the disclosure and the relationship to other components.

DETAILED DESCRIPTION

(7) FIG. 1a illustrates a valve control procedure known from the prior art in accordance with a dynamic function. In this case, the control procedure produces a maximum current value I.sub.s immediately following a point in time t.sub.1. The maximum current value, the so-called safety current intensity I.sub.s is selected so as to be such an amount that the desired opening rate and also a safety condition for opening the solenoid valve is achieved. The illustrated diamond shape indicates the point in time at which the valve starts to open. The maximum current value I.sub.s is maintained. The illustrated cross in the circle indicates the point in time at which the valve is completely open. Once the valve has been completely opened, the current intensity at the point in time t.sub.h is reduced to the desired holding current intensity I.sub.H in order to hold the normally closed valve in the open position.

(8) FIG. 1b illustrates a valve control procedure known from the prior art in accordance with a ramp function followed by a dynamic function. This procedure is to render it possible to open said valve more quietly. For this purpose, a ramp start current intensity I.sub.1 is adjusted initially at the point in time t.sub.1. The current I.sub.1 at the start of the current ramp is generally of such an intensity that the valve is not yet open in the case of each counter pressure. During the progression of time, the current intensity increases in a ramp-shaped manner until the end value ramp end current intensity I.sub.2 is achieved at the point in time t.sub.2. This end value may be variably defined and adjusted. The amount of the end value ramp end current intensity I.sub.2(p) that is required to open the valve is defined by the prevailing pressure in the system. The current intensity I.sub.2(p) therefore depends upon the pressure above which the valve must open. The ramp end current intensity I.sub.2 that is required for the valve to open is therefore to be determined so as to be of such an intensity that this is always sufficient in order to open the valve when the corresponding pressure is present. FIG. 1b illustrates a first current intensity progression by means of a continuous ramp line (for a first possible ramp end current intensity) and a second current intensity progression by means of a broken ramp line (for a second possible ramp end current intensity). The dependency of the ramp end current intensity I.sub.2 on the pressure renders possible a flat-line ramp increase. The current when a valve is completely open is therefore not much greater than the current when the valve starts to open. Furthermore, the excess force when the armature impacts against pole core is less in the case of a flat-line current ramp than in the case of a steep current ramp.

(9) Furthermore, following the ramp function, a dynamic function is performed in which the maximum current value, the so-called safety current intensity L is set. This renders possible a safety buffer by means of which it is ensured that the valve is actually opened even taking into consideration all possible eventualities. When the holding point in time t.sub.H has been achieved, the current may be reduced to the holding current value I.sub.H.

(10) Furthermore, the figure illustrates by means of a diamond shape the point in time at which the valve starts to open and in turn the fully open valve is indicated by the cross in the circle. The object in this case is that the valve switches during the ramp control procedure (in other words the valve achieves its end position). Furthermore, as a result of the ramp function, the current (or the magnetic force) when the armature impacts against the pole core is not as great as when the switching procedure occurs with a high current. The switching noise is accordingly quieter.

(11) FIG. 2 illustrates a possible embodiment of the device in accordance with the disclosure for the valve control procedure. The figure illustrates possible ramp functions. The figure illustrates a minimum ramp function (continuous line) and a maximum ramp function (broken line). The figure naturally only illustrates a section of the valve control procedure which includes by way of example a ramp function and a dynamic function. The ramp start current intensity I.sub.1 in accordance with the disclosure is dependent upon the pressure. FIG. 2 illustrates by means of I.sub.1min(p) a minimum ramp start current intensity for the point in time t.sub.1. Furthermore, the figure illustrates by means of I.sub.1max(p) a maximum ramp start current intensity. Commencing from this start, the current intensity continues to develop in a ramp-shaped manner until it achieves a ram end current intensity I.sub.2 at a point in time t.sub.2. FIG. 2 illustrates in turn by means of I.sub.2 min(p, T) a minimum ramp end current intensity and also by means of I.sub.2max(p,T) a maximum ramp end current intensity. In other words, the ramp end current intensity in the illustrated exemplary embodiment is dependent upon the pressure and the temperature.

(12) Furthermore, FIG. 3 illustrates a schematic view of the device V in accordance with one embodiment of the disclosure and the relationship to other components. The device V in the figure is configured as an ESP control unit. The device V may control one or multiple solenoid valves MV in a hydraulic brake system BS of a vehicle. The device V comprises means M. The means M support and/or render possible the procedure of controlling the solenoid valve MV. A means M is configured for this purpose by way of example as an ASIC. Furthermore, the means M render it possible to determine and adjust the ramp start current intensity and/or the ramp end current intensity. Furthermore, a pressure sensor S1 is provided. Information from the pressure sensor S1 may be received by the device V and processed. Furthermore, a temperature sensor S2 is provided and information from said temperature sensor is likewise processed by the device V. The sensors S1 and S2 may be a part of the hydraulic brake system BS. It is likewise conceivable that the hydraulic brake system BS comprises the device V.