DE102010028083A1 - Method for calibrating a pump motor in a pressure control system - Google Patents

Abstract

Method in which a pressure regulating system (5) produced in large numbers using high-volume technology is used to determine the pre-pressure (P _pre ) prevailing on an input side of one or more valves (9), each having an input side and an output side; wherein the pressure control system (5) comprises an electrically controllable, electric motor driven hydraulic pump (14) for generating pressure and wherein the speed of the pump is adjustable by changing the electric pump drive, wherein after the individual preparation (16) of the pump (14), a part thereof or the pump motor (15) or a part thereof or at least the partially prepared pressure control system (5)
a) flow rate and / or the speed of the pump (14) or the pump motor (15) directly or indirectly in dependence on
b) the strength of the electric motor control
measured individually on the basis of at least one or more measuring points (18) and stored individually in the pressure control system, wherein the measuring (18) takes place during or after the installation of the pump motor, the pump or the pressure control system into a secondary product or final product also produced by mass production, which is in particular a motor vehicle.

Description

The The present invention relates to a method according to the preamble of claim 1.

The older, unpublished patent application DE 10 2007 050 662 A1 of the same applicant on which the present patent application is based and whose features are expressly incorporated by reference in this application, relates to a method and apparatus for calibrating or diagnosing a motor vehicle brake system with a clocked operated pump. A preferred according to the present invention motor vehicle brake system (see also 1 This document), as also mentioned in the earlier application, is usually provided with two two-way valves (intake-exhaust valves), over the mutual switching of a locking of the wheels of a motor vehicle is avoided. The control of the two-way valves is usually carried out by means of a microcomputer-containing electronic control unit (ECU). In a motor vehicle brake system constructed in this way, a pump is usually provided for returning brake fluid or for an active pressure build-up. An optimized control of the two-way valves and thus an optimized braking operation can be achieved by the two two-way valves are controlled in dependence of the brake pipe pressure between a master cylinder and a wheel brake cylinder to a wheel brake. This brake line pressure is referred to in the sequence as a form.

In another type of motor vehicle brake pressure control system known per se, which is designed for the electronic stability program (ESP) function, a pressure sensor is generally available which controls the initial pressure in the brake pressure system caused by the tandem master cylinder, which pressure is also essentially the same for a pressure control is applied to the input side of a brake pressure control valve, can be measured. In the simpler brake pressure control system described in this application, as is generally produced for pure ABS vehicles (see, for example, US Pat. 1 ), this pressure measurement signal for the form is, however, regularly not available.

From the DE 10 2005 041 556 A1 A method is known for determining a primary pressure prevailing between a master brake cylinder and an intake valve of a wheel brake cylinder of a motor vehicle brake system without the use of a pressure measurement signal. According to the method in this case the form is determined taking into account the course of a tracking voltage of a clocked motor operated pump. For this purpose, a plurality of parameters of the voltage curve are measured and used in each case for determining a pre-pressure value, wherein an evaluation of the quality and / or reliability of the measured parameters, filtering and / or processing of the parameters and / or the pre-pressure values determined therefrom in the case of poor quality and / or reliability the measured characteristic values, an averaging of the admission pressure values determined from the various parameters takes place, whereby only pressure values of similar magnitude are taken into account and a temporal averaging of the admission pressure values is carried out for the attenuation of fluctuations.

in the Related to the pressure control method described above also known per se, for the determination of the form During operation of the pump, a pump current or speed / pressure characteristic in a data memory of a motor vehicle brake system controlling Deposit control unit. After the form calculated on the basis of the characteristic curve the two two-way valves are activated. This approach However, it is disadvantageous because the characteristic for each individual Pump and every single brake system due to manufacturing tolerances different fails. With increasing operating time the pump will suffer aging and wear, For example, on the rotary bearing of the pump rotor, the, affect the operating characteristics of the braking system. These Effects are referred to below as so-called "pump scattering".

task The present invention is therefore an easier to carry out and at the same time considerably more precise when pumping Method for determining the admission pressure in a motor vehicle brake system specify with a pulsed operated pump.

These The object is achieved by the method according to claim 1.

In accordance with the method according to the invention, a determination of the admission pressure P _is made in the case of a pressure regulating system manufactured in large numbers in high volume production. The pre-pressure prevails on an input side of one or more valves and largely corresponds to the pressure in any existing hydraulic lines, which are arranged in front of the input side of the valve. The valve has an input side and an output side with respect to the flow direction of the hydraulic fluid, to which a pressure difference is usually applied during operation. The pressure control system also includes an electrically controllable, electric motor-driven hydraulic pump for pressure generation. The speed of the pump is adjustable by changing the electric pump control and thus determines depending on the operating condition of the form or affects this ge together with a possibly existing brake cylinder.

• a) Förderleistung und/oder die Drehzahl der Pumpe oder des Pumpenmotors direkt oder indirekt in Abhängigkeit von
• b) der Stärke der elektrischen Motoransteuerung, z. B. dem Motorstrom,

individuell an Hand von mindestens einem oder mehreren Messpunkten ausgemessen und in der Druckregelanlage individuell gespeichert wird; wobei
das Ausmessen während oder nach dem Einbau des Pumpenmotors, der Pumpe oder der Druckregelanlage in ein ebenfalls großserientechnisch hergestelltes. Folgeprodukt oder Endprodukt erfolgt, welches insbesondere ein Kraftfahrzeug ist. Das Ausmessen von einem Kalibrierwert, -werten, -Punkten oder einer Kalibrierkurve erfolgt bevorzugt im Rahmen der Bandendeprüfung, insbesondere bei einem Kraftfahrzeughersteller oder besonders bevorzugt beim Hersteller eines Zulierferteils, das am Band des Kraftfahrzeughersteller montiert wird.At a later time, which is after individual production of the pump, a part thereof or the pump motor or a part thereof or at least the partially manufactured pressure control system, for example when the pressure regulator is manufactured or at a manufacturer of the electric motor, during one or more measuring operations, the

• a) capacity and / or the speed of the pump or the pump motor directly or indirectly as a function of
• b) the strength of the electric motor control, z. B. the motor current,

measured individually on the basis of at least one or more measuring points and stored individually in the pressure control system; in which
the measuring during or after the installation of the pump motor, the pump or the pressure control system in a also mass produced technology. Followed product or end product takes place, which is in particular a motor vehicle. The measurement of a calibration value, values, points or a calibration curve is preferably carried out within the framework of the tape end test, in particular at a motor vehicle manufacturer or particularly preferably at the manufacturer of a Zulierferteils that is mounted on the belt of the motor vehicle manufacturer.

Of the or the measuring points for calibration will be or will be preferred stored in the memory of an electronic control unit.

there give / give the measuring points or expediently a relationship between the speed of the pump and the motor current at.

The Engine or pump speed, can directly (eg via a Tachometer) or indirectly measured. Preferably takes place the measurement indirectly, for example by evaluation of a spectrum the structure-borne sound or airborne sound generated by the pump during pumping at different speeds. It is expediently an indirect Determining the speed by means of a structure-borne sound sensor and / or the measurement of airborne sound. Preferably for the formation of the speed signal to the spectrum of the indirect measured speed variable evaluated.

With the determined form on the input side is preferably the accuracy of the design of the electrical control and thus the regulated pressure setting on a valve improved, while doing with a measured and / or estimated pressure at the Output side of the valve output a determination of the pressure difference is made at the valve. That for the pressure setting used valve is preferably a per se known analogized Valve of a motor vehicle brake system. It is in particular around an analogized intake valve that connects to the input of a wheel brake cylinder connected is.

With The method described above results in connection with other pressure variables of the brake pressure control unit a functional relationship between the pump control and the form (brake line pressure) of the motor vehicle brake. To this Way, the brake line pressure can be without the use a pressure transmitter adapted to the operating condition of the pump determine. The process results in an increase the accuracy of the determination of the form. By the more accurate Knowledge of the form can be an analog valve control an intake valve much more accurately, thereby disturbing pressure surges, as with a inaccurate pressure control occur, much safer avoided can be.

The The invention also relates to a braking device consisting inter alia from an electronic control unit, a hydraulic power unit, a pump driven by a motor and at least one analog operated intake valve for a wheel brake cylinder in the electronic control unit, a pressure control method for the inlet valve is performed, which calibration variables for Determining the pre-pressure uses, with the method described above were determined.

In the method described above, it may be expedient to additionally determine typical characteristic values or parameters for a reference pump during the production of the pressure control system, thereby further improving the determination of the admission pressure. For example, this is an additional parameter which represents the electromotive force of the reference pump motor and can be determined repeatedly (ie several times in succession) under defined specifications (see example in FIG 2 ). From the values of this parameter determined for the reference pump, a statistical parameter can be derived. In this case, in particular, a pump is used as the reference pump, with which reference measurements are carried out in the development phase of the brake system as part of a prototype of the vehicle brake system. The considered parameter is determined in particular from the motor voltage dropping at the reference pump. The defined defaults are a set of test conditions, which are eg. Example, the installation of the pump in a special type of motor vehicle brake system, the temperature or the chemical composition of the brake fluid. Another requirement is that the parameter in no-load condition of the brake system, that is determined when the brake pedal is de-energized.

the same Parameter can continue, under appropriate, - in particular as far as possible the same specifications for a working pump can be determined. As a working pump, the "im Field "pump to be calibrated, the component one intended for installation in a motor vehicle or already in the vehicle built-in motor vehicle brake system is. The operating pump and the associated brake system are in particular the same type with the reference pump or the associated brake system. Also from the values determined for the reference pump Parameters may suitably a corresponding statistical characteristic.

Out for the reference pump or for the operating pump derived characteristics may preferably at least a ratio calculated as a measure of a possible deviation of the operating behavior of the operating pump is used to the performance of the reference pump.

According to one particularly preferred embodiment of the method is at least one calibration value, which is in particular a ratio, used to calibrate the operating pump by depending on from the at least one ratio a characteristic curve the operating pump to a corresponding predetermined characteristic of the Reference pump is adjusted. In other words, the characteristic goes of the operating pump from the characteristic curve of the reference pump the at least one calibration value or the at least one ratio by showing this characteristic of the reference pump with the at least a ratio or the calibration value or by means of one of the ratio (s) or the calibration value (s) dependent function / functions is charged. The characteristic of the Operating pump is therefore a function of the characteristic of the reference pump and the ratio. That way Once the characteristic curve determined for the reference pump use in a adapted to the conditions of the operating pump form. The characteristic curve for the reference pump can be any functional relationship between the parameter and the behavior of the Brake system descriptive size include. On this way can be used for the reference pump during the development phase of the motor vehicle brake system gained knowledge in full use also for the operating pump.

The Characteristic of the reference pump is preferably at any time the settlement with the at least one ratio or the calibration value. She is in particular in a data memory formed as a microcontroller control unit deposited. The calibration of the operating pump can be thus carry out anew at any time. Preference is given at the calibration, the method described above for the determination the pump speed as a function of the electrical Control of this calibration method in addition, so combined used.

It is possible and appropriate in the operation of the Motor vehicle later in periodic intervals more Perform calibrations, for example in the frame a maintenance of the motor vehicle in a workshop. To this In this way, aging and wear processes can also be achieved eliminate the operating pump and the entire motor vehicle brake system.

alternative or additionally, the pump characteristic can also be dependent a flow rate and / or the operating temperature of the pump can be determined.

The present invention sets in development of the measures described above with the following problem:
In modern brake systems, the wheel pressure control is often performed with analog controlled valves. For the control of the valves, the information of the current pressure difference across the valve is required. This is done in braking systems with ESC / ESP sensors by means of a pressure sensor in the brake master cylinder (THZ) and a model of the wheel pressure.

In a pure ABS brake system, where no cost reasons Pressure sensor in the brake master cylinder (THZ) is present, must be different be proceeded. Here is a THZ pressure model from the outlet voltage generated by the pump motor. However, this only works if the Connection of engine load (THZ pressure) and speed a known Size is.

With Knowledge of the individual characteristic of an engine with known Characteristics, the model works satisfactorily. This is for Example of the case when the above-mentioned reference pump motor is used. However, the problem is that by the in the production existing, above mentioned more often Exemplar scattering of engines printing errors come about, the one satisfactory function of the wheel pressure control at least complicate.

Further preferred embodiments will be apparent from the dependent claims and the following description of an embodiment Hand of figures.

1 a schematic representation of a vehicle brake system with only one illustrated wheel brake circuit,

2 a schematic representation of the course of the motor voltage during an on-off-on cycle of the supply voltage to the motor and

3 a schematic representation of an improved method of an analog ABS intake valve control with improved form determination.

Out 1 is an exemplary brake circuit of a dual-circuit, slip-controlled motor vehicle brake system 1 out. For reasons of clarity, the representation of the hydraulic circuit diagram is limited to 1 to one of two brake circuits, wherein only the first wheel brake circuit (I) is shown. In the embodiment of a brake assembly shown here is wheel brake 8th front left wheel VL and wheel brake 8th' of the rear right wheel HR connected to the brake circuit I. A division of the brake circuits to the front and rear axles is of course also possible. braking system 1 includes master cylinder 2 , which via hydraulic line 4 and pressure control unit 5 which is a hydraulic unit 6 (HCU) and an electronics unit 7 (ECU), with a wheel brake 8th connected is. The hydraulic unit 6 has a receiving body for hydraulic and electro-hydraulic components such as each electromagnetically actuated intake and exhaust valves 9 . 10 for every wheel brake 8th , From master cylinder 2 leads another hydraulic line 11 to a second wheel brake circuit (II). Starting from the wheel brake 8th leads a return connection 12 via the normally closed exhaust valve 10 to a low-pressure accumulator 13 which one, out of the wheel brake 8th As a result of ABS control cycles, it is possible to absorb the volume of hydraulic fluid discharged. The low pressure accumulator 13 feeds a suction side of a motor-driven hydraulic pump 14 , This is preferably of the type radial piston pump with in particular two cylinders and has in each case a suction valve on the suction side and a pressure valve on the pressure side. electric motor 15 and pump 14 are preferably designed as an aggregate (motor-pump unit) and allow, among other things, a return flow discharged hydraulic fluid in the direction of the master cylinder 2 , With pump 14 In addition, an independent, active pressure build-up can be made, as is necessary with additional functions of the brake controller, such as traction control (ASR) or driving stability control (ESP). For the operation of these additional regulations with active pressure build-up is before the inlet valve 9 an electromagnetically controllable and normally open isolating valve (TV) and a normally closed electronic switching valve (EUV) required.

During operation of the pressure control unit 5 can inlet valve 9 be closed during an ABS control intervention to further pressure build-up in the wheel by tandem master cylinder 2 temporarily to prevent. The pressure reduction normally to be carried out during an ABS control intervention is achieved by opening the exhaust valve 10 performed, creating hydraulic fluid in low-pressure accumulator 13 can drain away. However, the hydraulic fluid is stored only temporarily in the low-pressure accumulator NDS, since at a certain filling level of the low-pressure accumulator, the engine must 15 be activated so that the stored hydraulic fluid in the lines before inlet valve 9 is promoted. The valves EUV and TV extend the system so that the master cylinder can be disconnected from the brake circuits during an "active" control as in ESP.

In a partially open inlet valve (analog valve control) is set during a very accurate and metered pressure control to inlet valve 9 a pressure difference, which essentially from the pressure reduction operations made by the ABS control via exhaust valve 10 and before the inlet valve 9 pending form.

electric motor 15 the pump 14 is basically based on a separately excited DC machine, in particular a permanent magnet excited commutator machine whose speed is controlled by a pulse width modulation (PWM) at a constant supply voltage. In this case, for example, a predetermined number of fixed speed levels (for example 1-12) can be set by the controller. For speed control, the duration of the switch-on and switch-off phase of the supply voltage applied to the motor is modulated within a fixed interval (one PWM cycle, for example t = 60 ms). A full scale engine (speed level 12 ) corresponds to an applied supply voltage (switch-on phase) over the entire aforementioned interval. At lower modulation, the supply voltage of the motor is switched off after a certain time (for example, for speed level 8th after 40 ms), remains for the remainder of the PWM cycle (for example, for speed 8th ; 20 ms) is switched off (switch-off phase) and is only switched on again at the beginning of the switch-on phase of the next PWM cycle. With decreasing output (speed step), the pulse width of the switch-on phase (supply voltage at the motor) decreases and the pulse width of the switch-off phase (supply voltage at the motor off) increases.

In 2 is the voltage curve on the engine during an on-off-cycle of the supply voltage of the motor shown schematically. In the PWM switch-on phase E, the motor voltage corresponds approximately to the maximum available supply voltage. During the PWM switch-off phase A, the motor acts 15 as a generator and it can be tapped a generator voltage. In 2 are some, for the exemplary method relevant parameters of the voltage curve drawn: the last voltage ^value with still switched supply voltage U ^OnL , the first voltage ^value with re-switched supply voltage U ^OnF , the first voltage ^value after the supply voltage U ^Off , the difference between the last. Voltage value without switching the supply voltage and the first voltage value after the supply voltage U ^case, the lowest reached voltage value with the supply voltage U ^min, the sum of the voltage values with the supply voltage U ^Sum, the slope of the voltage drop with the supply voltage U ^Slope, the difference between the lowest reached voltage value when the supply voltage is switched off and the first voltage value when supply voltage U ^{Rise again} , time t ^case , until the voltage drops to zero.

Each of these characteristics of the voltage curve can be used in principle on the basis of a functional relationship and the results of calibration measurements to determine a value for the form. In order to be able to carry out evaluation in the processor of the electronic brake system that is as fast as possible, that is easy to control and to monitor, a simple, linear relationship between a parameter U and the form P is selected, for example: P in front = P 0 + P 1 × U

In this case, U is one of the characteristics of the voltage curve of the motor described above, preferably the slope U ^Slope . The parameters P ₀ and P ₁ for each characteristic can be obtained from calibration measurements as described below.

The from the different parameters per PWM cycle certain pre-pressure values can be averaged to the finally sought form to receive.

In 3 the pressure determination and control method according to the invention is explained in more detail with reference to an example.

step 16 symbolizes the production of the pump, the pump motor or the motor-pump unit in a production plant of a motor vehicle supplier.

In step 17 The motor-pump unit is installed in a pressure control unit (for example, electronic brake control unit).

In step 18 there is a tape end control. During the tape end control, once or in particular twice a measurement curve is indirectly determined, which indicates the motor or pump speed U _min as a function of the duty cycle (dc) of the PWM motor drive or of the motor current I.

The The invention thus also relates to a method for determining the engine speed (in the exemplary brake pressure regulator is no speed sensor available on the pump).

• A. über die Auswertung eines Körperschallsensors, der bei der Messung von außen angebracht wird, und/oder
• B. über die Auswertung des Spektrums einer Luftschallmessung, insbesondere auch ohne direkten Sensor ermittelt.

At the end of the tape in step 18 the speed is expediently

• A. on the evaluation of a structure-borne sound sensor, which is attached during the measurement from the outside, and / or
• B. on the evaluation of the spectrum of an airborne sound, in particular also determined without direct sensor.

From the measuring curve U _min (dc) or U _min (I), a slope _parameter P _{S_trocken is} determined, which depends essentially on structural _{variations of} the motor and the pump. The first measurement curve is determined before filling the brake system with hydraulic fluid. It is expedient if all hydraulic valves of the pressure control unit are controlled so that they are open. As a result, the pump can virtually run free with the lowest possible resistance.

The Determination of the measurement curve is done according to the here example described indirectly, in which with a structure-borne noise sensor recorded the frequency spectrum of the noise of the pump and based on the peak shift of resonant frequencies, the speed is determined.

Thereafter, a second measurement is carried out in which the pressure control system is filled and vented. In the second measurement in the filled state, a second gradient _parameter P _{S_nass} is then determined in the same way. In the second measurement expediently the separating valve TV ( 1 ) and the electronic switching valve EUV ( 1 ), so that the pump pumps against a comparatively high, substantially defined pressure resistance and is therefore relatively highly loaded. The river Oder the parameters determined during the second measurement also depend on structural variations of the motor and the pump.

If the parameter for the strength of the electric Motor control is the motor current, the current can, for example by a current sensor in the electronic motor control may be arranged, determined, or, more particularly, with a conventional clamp, with the motor current at the motor power supply in a particularly simple manner contactless is tapped.

step 19 will be carried out at a later date on the occurrence of an ABS regulation. During the ABS control, the slope U ^{Slope of} the voltage curve of the motor emf is determined as related to 2 explained.

In step 20 is the by operating the pump 14 generated form determined. When calculating the admission pressure according to the above-described relationship P _before = P ₀ + P ₁ × U ^slope , the variables P _{S_trocken} and P _{S_naß are used} for further correction of the calculated pressure in accordance with, for example, a linear correction.

step 21 symbolizes that of ECU 7 controlled control of an analogue controlled input valve 9 during an ABS pressure control. The ECU 7 processes this in addition to other sizes essentially the valve 9 ruling. Form, the wheel brake cylinder pressure at wheel 8th and one in the ECU 7 for the analog valve 9 stored valve characteristic.

The Thus, the invention proposes, inter alia, the engine line individually calibrated and suitable calibration values in the electronic Control unit (ECU). This may be preferred, in particular at the end of the tape, at one or more operating points (preferably at least two, to determine the characteristic slope) impressed a current and the engine speed are determined.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102007050662 A1 [0002]
• DE 102005041556 A1 [0004]

Claims (10)

Method in which in a large-scale production of high-volume pressure control system ( 5 ) a determination of the pre-pressure (P _pre ), at an input side of one or more valves ( 9 ), which each have one, input side and an output side prevails, is carried out, wherein the pressure control system ( 5 ) an electrically controllable, electric motor-driven hydraulic pump ( 14 ) and wherein the rotational speed of the pump is adjustable by changing the electric pump drive, characterized in that after the individual production ( 16 ) of the pump ( 14 ), a part thereof or the pump motor ( 15 ) or a part thereof or at least the partially prepared pressure control system ( 5 ) the a) flow rate and / or the speed of the pump ( 14 ) or the pump motor ( 15 ) measured directly or indirectly as a function of b) the strength of the electric motor control individually on the basis of at least one or more measuring points ( 18 ) and stored individually in the pressure control system, the measuring ( 18 ) takes place during or after the installation of the pump motor, the pump or the pressure control system in a likewise mass-produced technically derived product or end product, which is in particular a motor vehicle. A method according to claim 1, characterized in that the measuring in the context of the tape end test ( 18 ), in particular special of a motor vehicle manufacturer takes place. A method according to claim 1 or 2, characterized in that the one or more measuring points in the memory of an electronic control unit ( 7 ) is / are stored. Method according to at least one of claims 1 to 3, characterized in that the one or more measuring points a relationship between the speed of the pump ( 14 ) and motor current indicates. Method according to at least one of the claims 1 to 4, characterized in that the engine or pump speed is measured indirectly. Method according to claim 5, characterized in that that the speed measured by means of a structure-borne sound sensor is and / or about the measurement of airborne sound. Method according to at least one of the claims 1 to 6, characterized in that the spectrum of the indirect measured speed variable is evaluated. Method according to at least one of the claims 1 to 7, characterized in that with the determined form on the input side, the accuracy of the design of the electrical Control and thus the regulated pressure setting on a valve is improved, with a measured and / or estimated Pressure on the output side of the valve output a determination of the Pressure difference is made at the valve. A method according to claim 8, characterized in that the valve is an analogized hydraulic valve ( 9 ) in a motor vehicle brake system ( 5 ), in particular an analogized inlet valve ( 9 ) of a wheel brake cylinder ( 8th ) is. Braking device consisting of an electronic control unit ( 7 ), a hydraulic power unit ( 6 ), one of an electric motor ( 15 ) driven pump ( 14 ) and at least one analogously operated inlet valve ( 9 ) for a wheel brake cylinder ( 8th ), characterized in that in the electronic control unit ( 7 ) a pressure control method for the inlet valve ( 9 ), which uses pump-individual calibration variables (P _{S - dry} , P _{S - wet} ) for determining the pre-pressure (P _pre ) determined by the method according to at least one of claims 1 to 9.