FR2844055A1 - TEST CONTROL METHOD AND DEVICE - Google Patents

Abstract

Method for controlling at least one electromechanical component of a brake regulation system according to which - a feedback message quantity characterizing the electrical reaction (i) of the components to a command is determined, - the command instant which characterizes the start of the electrical control (ΔTO) is chosen so that the feedback quantity is present at a predetermined feedback message instant in the control unit of the brake regulation system.

Description

Field of the invention

  The present invention relates to a method and device for controlling at least one electromechanical component of a brake regulation system according to which a quantity of return message ca5 determining the electrical reaction (i) of the components to a command is determined.

  State of the art According to the document DE 39 22 900 A1, a method and a circuit are known for monitoring the electromagnets and detecting faults in the winding or in the supply line. For this, a proprietary ap10 circuit captures the time of current drop of the electromagnet after its

  cut and compare it to a predetermined threshold; in case of difference the device generates a fault signal. The magnet receives a test pulse for this, the duration of which is not sufficient to produce the mechanical actuation of the electromagnet.

  For example, a hydraulic brake system is known.

according to document DE 197 12 889 Ai.

  Disclosure of the invention The present invention has as its starting point a method for controlling at least one electromechanical component of a brake regulation system in which - the electrical control of the component is carried out during an interval of a duration so short that there can be no mechanical reaction from the component, and

  a return signal is supplied to characterize the mechanical reaction of the component in response to the command.

  The method according to the invention is characterized in that the control instant which characterizes the start of the electrical control (AT0) is chosen so that the return quantity is present at a predetermined return message instant in the brake system control system.

  This makes it possible to adapt the instant of the arrival of the return quantity to the rate of the brake regulation system.

  An advantageous embodiment is characterized in that the instant of the return signal is at the same time the instant of detection of the 3s brake regulation system. This removes the intermediate recording of return signals until the next detection time.

  The expression "detection instant" represents the instant at which a signal (a voltage) is recorded (detected). The moment of detection

  is the instant at which an analog signal gives a digital value.

  According to an advantageous development, as an electrical reaction of the components, it is determined that a predetermined threshold is exceeded by an electrical quantity. Exceeding a limit value by

  an electrical quantity is determined in a simple manner.

  The electrical quantity according to an advantageous development is the electrical intensity.

  An advantageous embodiment is characterized in that

  that for determining the command instant, at least one quantity is used which characterizes the return time between the threshold being exceeded by the electric quantity and the presence of the return quantity in the brake control system. This return time is a systematic property already known in the application phase.

  An advantageous development is characterized in that to determine the command instant, use is made of: - a lower limit value for the return time, and

  - an upper limit value for the return time.

  This makes it possible to determine the instant of

  independent control of tolerances or return time.

  The device for controlling at least one electromechanical component of a brake regulation system comprises: a control means with which the electrical control of the component is ensured over such a short time interval that there can be no mechanical reaction of the component, and - means for determining the reaction with which it is determined

  a return quantity characterizing the electrical reaction of the component in response to the command.

  This device is characterized according to the invention in that the control instant characterizing the start of the electrical control is chosen in the control means so that the quantity of return message arrives at a predetermined return message instant

  in the control unit of the control system.

  An advantageous development of the device is characterized in that the electromechanical components are at least: - an inlet valve and / or an outlet valve and / or

  - a brake pump delivery pump.

  Drawings The present invention will be described below with the aid of an exemplary embodiment represented by the appended drawings in which: - Figure 1 shows an electrical control of a solenoid valve or a discharge pump, - Figure 2 shows in a first step, the basic idea of the invention, - Figure 3 combined with Figure 2 shows other characteristics of the invention, - Figure 4 shows the process of the invention ,

  - Figure 5 shows the relationship between the instants of detection and the instants of control.

  Description of embodiments

  A hydraulic brake system is known for example according to document DE 197 12 889 A1. The hydraulic brake circuit includes inlet valves and outlet valves for the wheel brakes, the control of which enables pressure to be established or reduced in the wheel brakes. This circuit also includes discharge pumps which ensure a reduction in pressure, independent of the

  driver in the wheel brakes. The switching valves allow switching between an action on the brakes dependent on the driver and an action on the brakes independent of the driver.

  The present invention is suitable, for example, for monitoring the solenoid valves of the hydraulic circuits described above (in particular the inlet and outlet valves) as well as the discharge pumps.

  The electric control command of the valves or of the discharge pumps, for example by a voltage pulse, is so short in time that there can be no actuation of the valve or starting of the pump motor. This allows silent control of the components described (especially even during operation). In addition, the brief electrical control or test command cannot cause any mechanical wear of the components. A duration of, for example, about 500 microseconds has been confirmed as being of interest for the test command. For the test command with a voltage pulse, one can for example monitor the current in the

solenoid valve coil.

  Such an electrical control is represented in FIG. 1. On the abscissa, the time t is represented and on the ordinate, the electric voltage u (t) (solid line) and the electric current i (t) (broken line).

  The solenoid valve is controlled by a voltage pulse of width AT. This width is so short that it: - causes a measurable rise in intensity i (t) in the solenoid valve coil, but - cannot cause mechanical movement, for example of the armature of the solenoid valve. It is estimated that a valve works properly according to this

  control test if in the time interval AT, the current i (t) exceeds a predefined threshold iO. This occurs in Figure 1 at time t0. The overshoot, that is to say the time interval during which the current is greater than the threshold, bears the reference AT1.

  As soon as this current exceeds the threshold, there is a continuous return signal which continues from the control unit of the solenoid valve concerned to a control device. The control device which receives this feedback information can for example be the control device of the anti-lock system, of the traction control regulation or of the control system of the driving dynamics (ESP = Electronic Stabilization Program). The time at which each of the messages or the return information arrives in the control device is tainted with the tolerances of the components (in particular the RC elements) in the control unit; however tolerances are important. The re25 turn time is for example between 0.25 ms and 2.25 ms, i.e. the valve return information has a delay of 0.75 ms up to 2.25 ms

  to get into the control unit.

  This delayed arrival of the valve return message in the control unit (as well as other information) is shown in Figure 2.

  We will first describe the construction of Figure 2 which shows two diagrams with the time t on the abscissa on the same scale.

  The upper diagram bearing the reference 200 represents the control or test command of the solenoid valve coil. In this diagram, "0" indicates that at this time there is no command and "1" indicates that there is a command at this time. The pulse represented by width AT it may for example be the voltage pulse of FIG. 1. The current exceeds the limit value i0 at the instant at which is plotted

  the left limit of the time interval AT1.

  The lower diagram bearing the reference 201 shows the state of the message or of the feedback information in the control unit. s There are three areas: - the area with the reference "0": it corresponds to the absence of a return message, - the area with the reference "1", white area: it reads with certainty a return message or information return concerning the exceeding of a limit value by the current,

  - the hatched area: there may be a return message.

  The characteristic width of the test control pulse is of the order of 500 microseconds. For a non-defective valve, the current threshold i0 is typically reached between 50 15 microseconds and 150 microseconds.

  Diagram 20 represents the width control pulse AT as well as the width time interval AT1 during which the current exceeds the threshold. In this interval AT1, the control unit of the solenoid valve continuously sends, for example, a high level signal which characteristically indicates that the solenoid valve is operating correctly. If for example because of a defective coil we could not reach the threshold for the current, there would be no emission of signal

high level.

  The "travel time" of the message or the return signal 25 (ie the time traveled until the high level signal arrives at the control device, for example a control device of a ABS, ASR or ESP), takes values between tdmin and tdmax due to the tolerances of the components. This "travel time" is a property of the practical solenoid valve or its control unit. This travel time is always the same for a certain solenoid valve (for example 1.2 ms) but for different solenoid valves or their power stages, this travel time varies between tdmin and tdmax.

  This means that the journey time is a characteristic specific to

each copy of valve.

  The return message from diagram 201 is shifted and counted between tdmin and tdmax. This is the area plotted on the left. At any time in this hatched area, the state of the return message

  changes from level "0" to level "1" in the control unit.

  As soon as the current in the solenoid valve exceeds the threshold i0, the state of the solenoid valve control unit remains at level "1". This makes it possible to suppose that there will be permanently signals of

  high level sent to the control unit.

  The last high level signal is sent by the solenoid valve or its control unit at the end of the width AT of the test pulse in diagram 201; this means that the test signal in diagram 200 suddenly returns from level "1" to level

"0".

  As the test concerns a single solenoid valve, this last high level signal has the same travel time as the first high level signal. This explains the hatched area on the right in diagram 201. The state of the return message in diagram 201 remains at level "1" for a time interval AT1. The fact that this time interval AT1 exists both in the top diagram 200 and in the bottom diagram 201 is the reason why the "journey time"

  is always the same for a certain solenoid valve.

  Starting from FIG. 2, we pass to FIG. 3. It can be seen that FIG. 3 is not overloaded with information because certain inscriptions in FIG. 2 have been deleted.

  The new element in FIG. 3 is a third diagram bearing the reference 202. This new diagram added only shows a time axis t also directed to the right. Along this time axis, the instants of detection of the operating system (for example the control system of the ABS, ASR or ESP system) have been plotted. A detection is carried out for example every 5 milliseconds, that is to say for example at the times indicated corresponding to 0 ms and 5 ms. It is desirable to have information concerning an intact valve at these detection times. This is why the basic idea of the invention is that the white area characterized by the state "1" in diagram 201 contains the value 5 ms. This means that at the moment of detection, there is precisely a return message. From the knowledge of the instants tdmin and tdmax, it is possible to control the solenoid valve controlled in diagram 200, by shifting it in time for the instants of detection of the operating system so as to have at the moment of detection, a guaranteed return message in case of

valve intact.

  In the basic state of the brake system, the inlet valves are open and the outlet valves closed. The test control of the inlet valves consists in controlling them as for a closing operation. The test command for the outlet valves consists of controlling them as for an opening operation.

  FIG. 4 schematically shows the progress of an embodiment of the method of the invention. In block 400, the electromechanical components of the brake regulation system are controlled. In block 401, it is then determined whether an electrical quantity 10 (for example the current i) has exceeded a threshold (for example a threshold iO), that is to say that an operation is being carried out. If this is not the case (n) we return to block 400 and the command continues, that is to say that there is no new command with a starting point of the control pulse which would be changed from the system's operating rate). In the opposite case (y) we go to block 402 and send a return signal or return message to the brake control system, that is to say

  the test order is completed again.

  The main element of the invention consists in predefining the instants of detection of the cadence system of the brake control system and in controlling the electromechanical components of the brake system.

  brake regulation offset in time.

  This situation is shown diagrammatically in FIG. 5. In block 501, the instants for detecting the cadence of the brake regulation system are predefined. These times are transmitted to block 502. Block 502 also contains (for example in the form of a fixed record) the minimum value and the maximum value of the return time.

  The output signals of block 502 contain the instants for controlling the electromechanical components determined from knowledge of the instants of detection (block 501) and of the travel times (block 502). The output signals from block 502 are transmitted to block 503. Block 503 corresponds to the control of the electromechanical components of the brake control system. The return message is then available to

  moments of detection in block 501.

  Since there is no mechanical switching of the valves of the pump, neither does it cause annoying switching noises.

Claims (7)

CLAIMS R E V E N D I C A T I O N S   1) Method for controlling at least one electromechanical component of a brake regulation system according to which - a quantity of feedback message characterizing the electrical reaction (i) of the components to a command is determined, characterized in that   the control instant which characterizes the start of the electrical control (AT0) is chosen so that the return quantity is present at a predetermined return message instant in the control device of the brake regulation system.   2) Method according to claim 1, characterized in that   the instant of the return message is at the same time the detection instant 15 of the brake regulation system.   3) Method according to claim 1, characterized in that   the electrical reaction of the components to exceeding a predefined threshold 20 (iO) is determined by an electrical quantity (i).   4) Method according to claim 3, characterized in that for the determination of the control instant, at least one quantity is used characterizing the return time between the threshold being exceeded by the electric quantity and the arrival of the quantity back   in the brake control system.    ) Method according to claim 4, characterized in that the determination of the command instant uses - a lower limit value for the return time (tdmin), and   - an upper limit value for the return time (tdmax).   6) Method according to claim 3, characterized in that   the electrical quantity and the electric current (i) passing through the component.   7) Device for controlling at least one electromechanical component of a brake regulation system according to which: - a control means provides electrical control of at least one component over a sufficiently short time interval so as not to produce any mechanical reaction of the component, and - a reaction determining means using which the electrical reaction of the components is determined for a quantity of feedback message characterizing the control, characterized in that   - the control instant characterizing the start of the electrical control in the control means is chosen so that the return message quantity arrives at a predetermined return message instant in the control device of the regulation system.   8) Device according to claim 7, characterized in that the electromechanical components are at least: - an inlet valve and / or an outlet valve and / or   - a discharge pump from the brake control system.