DE19732229A1 - Device and method for controlling the drive train of a motor vehicle - Google Patents

Abstract

The invention concerns a system for controlling units disposed in a motor vehicle drive train. The vehicle further comprises electrically actuated wheel brakes, preferably designed with one or two motors. Control devices are provided which control or regulate the functions of at least one of the units disposed in the drive train and/or the function of the wheel brakes, and, in reaction to a delivered signal, influence the potential of at least one of these units. At least one electrical energy storage device is operatively connected to the electrically actuated wheel brakes in order to supply energy. The essence of the invention is that diagnostic devices are provided which determine the potential of at least one of the energy storage devices. The diagnostic devices then generate the signal as a function of the determined potential of at least one of the energy storage devices, such that the potential of at least one of the units disposed in the drive train is adapted in a manner oriented to driving safety to the determined potential of at least one of the energy storage devices, and/or the function of the wheel brakes is influenced in order to generate a predetermined braking effect.

Description

State of the art

The invention relates to an apparatus and a method to control the braking system of a vehicle with the Merk paint the independent claims.

A variety of under different configurations of brake systems are known from the prior art. An overview of brake systems is provided, for example, by the Bosch Automotive Paperback, 21 . Edition, pages 594 to 643 (Bosch Automotive Handbook, 3rd edition, page 594 to 643). Such brake systems can be formed as a hydraulic, pneumatic or electromechanical brake system. The electrical actuation of such brake systems consists, for example, in the actuation of the valves, which influence the brake pressure in the wheel brakes hydraulically or pneumatically. In the case of an electromechanical brake system, the wheel brakes are actuated by an electric motor. For brake systems of motor vehicles of a certain size, the legal provisions stipulate that in addition to the service brake, the vehicle driver can reduce the vehicle speed during normal operation, an auxiliary brake system and a hold-open system can also be seen. The auxiliary brake system enables the vehicle driver to gradually reduce the vehicle speed or the vehicle speed change in the event of a fault in the service brake system or to bring the vehicle to a standstill. The parking brake system ensures that the vehicle can be kept at a standstill by mechanical means on an inclined roadway and in particular in the absence of the driver.

An electromechanical brake system is an example known from WO-A 94/24453. There is a wheel brake se described, in which the clamping force by a Electric motor is generated. Particular attention is paid to the like electric motor operated wheel brakes as well general for the other, electrically controlled wheel brakes to ensure the reliable functioning of the brake system The reliability of the batteries provided power supply in the foreground. In particular special must also the operational safety of the braking system then be guaranteed if there is insufficient stored ter electrical energy insufficient braking effect more can be applied.

From DE, A1,35 02 100 a pressure medium brake system for motor vehicles is known, in which two energy stores are provided for the energy supply of the brake system, it being possible to switch over to the other store depending on the state of charge of one energy store. If the state of charge is too low, the driver of the vehicle can be notified optically and / or acoustically.

From DE, C1,39 36 638 an electrical energy supply is known in a motor vehicle, in which, depending on the state of charge of the vehicle battery, the consumers are switched off, which are not absolutely necessary for the safe operation of the vehicle.

In DE patent application 19548560.2 , a brake system with electrically actuated wheel brakes is known, which comprises a parking brake that can be actuated by the driver. At the start of the vehicle, a test sequence for checking the functionality of the brake system is initiated, in the course of which at least one wheel brake is subjected to a control variable that corresponds to a predetermined minimum braking effect. The parking brake is then not released if the specified minimum braking effect is not achieved on at least one wheel. The state of charge of the battery or batteries is not measured.

The object of the present invention is to drive safety-critical situations with electrically controllable To prevent braking systems.

This is ge by the features of the independent claims solves.

Advantages of the invention

The invention relates to the control of units in Drive train of a motor vehicle are arranged. Next indicates the vehicle electrically, preferably single or twin-engine wheel brakes. There are Control means provided the functions of at least one of the Units arranged in the drive train and / or control or regulate the function of the wheel brakes and the potential in response to a supplied signal affect at least one of these units. At least an electrical energy storage medium is for energy consumption supply with the electrically operable wheel brakes  connected. The essence of the invention is now that Diagnostic means are provided by means of which the potential at least one of the energy storage means is detected. The Diagnostic means then generate depending on the detected Po potential at least one of the energy storage means the Si gnal such that the potential of at least one of the in powertrain arranged units to the detected potential at least one of the energy storage means driving safety is oriented and / or the function of the wheel brake sen to apply a predetermined braking effect is flowing.

The invention has the advantage that when there is insufficient Provision of energy through the energy storage means security critical situations through an intervention in the Drive train and / or in the wheel brakes are avoided.

The potential of the energy storage means can be Represented energy state of charge of the energy storage means will. It is particularly provided that the diagnosis means at least two different energy charge states de capture the energy storage means and the Si produced gnals represent the different energy charge states animals. This configuration allows driving safety increasing measures very precisely to the available ones energy can be adjusted.

The potential of one of the arranged in the drive train units or the potential of the entire drive train by the drive power and / or by the drive torque of the vehicle, especially by the maximum possible An drive power and / or by the maximum possible drive moment of the vehicle. With that the current or the maximum possible drive power the current or the maximum possible drive  moment of the vehicle to which is available for braking adapted energy.

In the drive train of the vehicle, at least one Vehicle engine, in particular an internal combustion engine, a Coupling, a transmission, a retarder and / or an exhaust gas flap may be provided. By appropriate control the These units can drive the torque or Drive power to that available for braking Energy to be adjusted.

In an advantageous embodiment it is provided that the Potential of at least one arranged in the drive train Unity to the detected potential of at least one of the ener Giespeicherermitt is adjusted so that to support tion of the braking effect of the vehicle at least one of the im Drivetrain arranged units influenced in this way is that he has a braking effect on the vehicle is aimed. In this embodiment, the delay can tion request of the driver by means of the Si according to the invention gnals are supported by referring the drive torque approximately the drive power according to the potential the energy storage means down to negative values is decorated. Such negative drive values then act as Drag torques on the driven vehicle wheels. Is the Only a small amount of energy available for braking, this way you get a wheel drag torque, that the service brake functions (auxiliary and residual brakes kung) and increases driving safety. In particular a control of the vehicle engine is particularly featured see to induce a so-called engine drag torque ren.

In particular, it can be provided that in response to the Signal, i.e. if there is insufficient energy supply, the  Function of at least one of the arranged in the drive train Units, especially the vehicle engine, so affected is that a starting of the vehicle, especially a Starting the vehicle engine is prevented. Here is preferably provided that the prevention of the start of the Vehicle engine by locking the corresponding position a driving switch is achieved.

In a particularly advantageous embodiment, it is provided hen that when the signal is at least a potential nes represents the energy storage means to start of the vehicle engine arranged in the drive train is sufficient to prevent the vehicle engine from starting. This can also prevent the vehicle from starting by locking the corresponding position of a Driving switch can be achieved. This configuration has the Background that the energy storage means in general both for power supply to the electric brakes can also be used to start the vehicle engine. The high electricity capability, i.e. the assets of the energy storage means a high current is available at the start of the vehicle engine in general, decreases with the potential, the La deState. Is the potential of energy storage for a start of the vehicle engine too low, then according to the Watering a start attempt of the vehicle engine under bound and thus prevents unnecessary energy consumption. In this case (low state of charge) the Ver Providing standing energy to maintain others functions are used.

According to the invention it can be provided that the electrically be actuable wheel brakes different operating functions such as service brake function, auxiliary brake function or have parking brake function. Depending on the Available energy, that is, depending on which he  generated signal, these operating functions are released. In this embodiment, only those with the current one available energy safely operated brake functions released. In this way, one is enough appropriate availability of the braking functions ensured.

It when the taxes mentioned with tel are designed such that in response to the signal the powertrain is affected so that the vehicle speed is set in a predetermined manner. This means that during a trip with restricted Ver Availability of the brake system due to an insufficient energy gievorrat the driving safety through a correspondingly safe safety-oriented setting of the vehicle speed is guaranteed. This configuration can provide be that the setting of the vehicle speed in Meaning a limitation to higher vehicle speeds there happens. Furthermore, the setting of the vehicle speed happen such that the maximum vehicle speed is gradually reduced. Here, the Setting depending on the represented by the signal potential of the energy storage means are made. The limitation and / or reduction may depend on that potential represented by the signal can be selected.

With an electromotive brake can be provided be that vehicle braking that can be specified as braking functions conditions (for example 5.8 m / s², 2.9 m / s², 1.5 m / s²) depending on Energy storage content can be taken automatically. Furthermore, the driver of the vehicle is corresponded to The appropriate display device informs whether currently such a braking function is effective. One is in particular Step-by-step relapse strategy in the event of a brake failure see. A "last" measure in the context of such a re case strategy would then be the automatic locking of the  Parking brake function when the vehicle speed in is substantially zero. So it finds an active assignment the possible vehicle delays to the memory stop the energy storage instead.

As already mentioned at the beginning, the electrically operated Wheel brakes as electromechanical, hydraulic or pneuma table brake be formed.

The invention further relates to a method for controlling units which are arranged in the drive train of a motor vehicle, having electrically actuable wheel brakes and at least one energy storage means which, in order to supply energy, with the electrically actuable, preferably single or two-motor, wheel brakes ( 160-163 , 170-173 ) is operational. The potential of at least one unit arranged in the drive train is influenced in response to a supplied signal. Furthermore, the potential is at least one of the energy storage means detected. Depending on the detected potential of at least one of the energy storage means, the signal is generated in such a way that the potential of at least one unit arranged in the drive train is adapted to the detected potential of at least one of the energy storage means in terms of driving safety.

Further advantages result from the following Be writing of exemplary embodiments or from the dependent ones Claims.

drawing

The figure shows an overview block diagram of a before Preferred design of a brake system with an electrome mechanical application of the wheel brakes.  

Description of exemplary embodiments

The invention is described below with reference to the drawing illustrated embodiments explained in more detail.

Fig. 1 shows a preferred embodiment of an electromotively operable brake system for vehicles, which comprises a two-circuit electrical system. In Fig. 1 four brakes are shown, which are assigned to the four wheels of the vehicle. The wheel brake 170 is, for example, the right rear wheel, the wheel brake 171 the left front wheel, the wheel brake 172 the left rear wheel and the wheel brake SE 173 the right front wheel. The wheel brakes are each connected to the electromotive actuators 160 , 161 , 162 and 163 via mechanical connections 160 a, 161 a, 162 a and 163 a. The electromotive actuators are controlled by an electronic control unit 120 via the corresponding output lines. For safety and reliability reasons, the electrical system supplying the actuators with voltage is redundant. The actuators assigned to the wheel brakes can be powered from both batteries (energy storage means). In this sense, the actuators 160 , 161 , 162 and 163 are connected via supply lines + E1 to the positive pole of a first battery 101 . The actuating devices are correspondingly linked to the positive pole of a second battery 100 via supply lines + E2. The electronic control unit 120 , which comprises at least one microcomputer, is fed via ei ne input line from a pedal value transmitter 130 at least one variable for the degree of actuation of the brake pedal as a measure of the driver's braking request. Furthermore, the electronic control unit 120 is supplied with signals from block 131, which detects the operating variables of the brake system and / or the vehicle. Such operating variables are, for example, wheel loads, variables for the set actual values of the braking effect on each wheel brake (e.g. current, braking torque, temperature, braking force, slip, etc.), wheel speeds, vehicle speed, brake pad wear, etc. . Furthermore, the electronic control unit 120 is supplied with current from at least one of the batteries 101 and 100 . The corresponding connecting line is not shown in FIG. 1 for reasons of clarity.

The batteries 100 and 101 are connected to the energy diagnosis means 110 , which supply the status signals 112 and 111 to the control unit 120 .

The reference number 140 denotes control means by means of which various functions of the (not shown) drive train of the vehicle can be influenced. This can be a control unit for controlling or regulating the functions of the vehicle engine and / or a clutch, a transmission, a retarder and / or an exhaust gas flap. However, these control means can also be an interface to the units 145 and 150 that control or regulate the functions. Furthermore, the control means 140 can switch energy-consuming units 190 of the vehicle on or off.

From the brake control unit 120 , the display units 135 can also be controlled with the two warning lamps 135 a, 135 b.

The brake system shown has a parking brake not shown Darge mechanical or powered by electrical energy. To control the parking brakes on the control unit 120 connections are provided, of which lines 200-203 from the control unit 120 lead to the adjusting devices 160 , 161 , 162 and 163 . The parking brakes can be actuated through these lines 200-203 .

The basic functioning of the control of such a braking system is as follows. The electronic control unit 120 forms from the supplied actuation level signal of the brake pedal (block 130 ) in accordance with additional operating variables such as wheel loads, brake pad wear, tire size, battery voltage, etc. (block 131 ) for each wheel brake a setpoint value, which is a measure of the other Wheel brake represents the braking effect to be set (e.g. braking torque, braking force, current through the electric motor, torsion angle of the electric motor, wheel slip, wheel speed, etc.). Controller units, which generate an output signal in the sense of an approximation of the actual values to the target values in accordance with a predetermined control strategy (e.g. PID), regulate the braking effect to the predetermined target value. The actual values can either be measured on the wheel brakes or calculated from the quantities measured there. In example, the contact pressure of the brake pads or the drive torque of the motor can be derived from the current through the electric motor, which is a direct measure of the braking effect exerted on the corresponding wheel brake. Furthermore, the applied braking force or braking torque can be measured by strain gauges or other suitable sensors and the braking torque applied can be determined in accordance with the brake design. The angle of rotation can be determined by appropriate angle sensors on the wheel brakes.

The controller output signals for each wheel brake are in An control signals for the corresponding control devices set. Depending on the version of the electrical control direction containing motor, whether stepper motor, commutator mo gate or motor with electronic commutation, provides the  Control signal size a step number to be output Duty cycle, a voltage value, a current value, etc. In the preferred embodiment, in the Stel Commutator motors are used, which have a Full bridge output stage through a pulse-shaped control signal with variable duty cycle in both directions are currentable. The duty cycle is determined in accordance with Re gel output signals formed and adjusted the motor against restoring forces to a predetermined position.

The state of charge of the two energy stores E1 101 and E2 100 is detected and monitored by the energy diagnosis unit 110 in a manner known per se, for example by a combination of voltage monitoring with a superimposed current load. The energy diagnosis unit 110 transmits the status signals 111 and 112 to the electronic control unit 120 of the brake, which represent the respective charge state of the energy stores 100 and 101 . The status signal 111 and 112 takes according to the state of charge of the energy store in the range of 0-100% of the maximum load capacity of the energy store in this embodiment, for example four states ( 0 , 1 , 2 , 3 for E1 and 0, A, B, C for E2) on, for example 0-10%, 10-40%, 40-60%, 60-100%) The brake control unit 120 processes and links these status messages 111 and 112 in the sense of an energy balance and provides them based on the determined possible energy position, the brake function that can be achieved for the vehicle (e.g. service brake, auxiliary brake or parking brake) is released.

Initiated by the control unit 120 , the driver is informed optically and / or acoustically by the driver display unit 135 about the availability of the braking functions or about the state of charge of the batteries.

If the control unit determines by evaluating the status signals 111 and 112 that the energy supply is not sufficient to ensure braking functions, a corresponding signal S is sent to the control means or to the interface 140 . The signal S can influence vehicle functions, in particular the drive train.

When starting the journey and insufficient energy supply to ensure braking functions, for example, the vehicle engine is not started up. This can be done by blocking a corresponding position of the travel switch 145 . For example, the "start engine" stage of the driver-operated driving switch (ignition starter switch) can be blocked. In this way, safety-critical driving situations are counteracted by the driver putting the vehicle into operation despite inadequate braking action.

The energy storage means are generally used both for Power supply to the electric brakes as well Start of vehicle engine used. As mentioned at the beginning the high current capability, i.e. the power of energy, decreases storage means to start the vehicle engine a high To provide electricity, generally with the charging condition of the battery. Is the state of charge for a start of the vehicle engine too low, a start attempt of the Vehicle engine prevented and thus an unnecessary energy consumption can be prevented. In this case (low drawer state), the energy still available can be used Maintaining other important functions will.

Furthermore, or alternatively, during the drive at a limited by insufficient supply of energy braking function of the means 140 by the block 150, the currently and / or the maximum available on driving torque of the vehicle or the current and / or the maximum available drive power of the Vehicle can be limited. This can be done directly by an appropriate intervention in the engine control. Alternatively or additionally, the clutch control and / or the transmission control of the vehicle can also be modified in the sense of such a limitation.

The functions of the drive train can also be controlled by a gradual release of the drive torque or the drive performance of the vehicle engine according to the energy content of the batteries are affected.

Similarly, a request for deceleration (Bremsenbe operation) of the driver are supported by the signal S, by reducing or reducing the powertrain tes drive torque is generated. Thus a Drag or braking torque on the driven vehicle wheels indu graces. This can be done in a known manner by the vehicle engine and / or through the gearbox (smaller gear) and / or by activating a retarder and / or by operating a flap in the exhaust system of the driver Witness engine (exhaust flap) can be achieved.

Furthermore, the vehicle maximum speed can be limited during the journey with a braking function restricted by an inadequate energy supply via the means 140 through the block 150 . For this purpose, the control or regulation of the vehicle engine is modified or influenced accordingly. The maximum speed of the vehicle can be gradually reduced when the signal S is present. Furthermore, it can also be provided that the signal S contains quantitative information about the energy balance determined in the control unit 120 of the two energy stores 100 and 101 . Thus, it can be provided that the maximum permissible vehicle speed is set lower with a lower available amount of energy than with a higher available amount of energy.

It can further be provided that in the event of insufficient energy, for example due to a failure of the power generator function, the control means or interface 140 can switch off or operate energy consumers 190 , whose function contributes less to driving safety than the brake. As a result, the braking function can be at least largely maintained, in particular if the energy balance is inadequate while the vehicle is traveling.

As already mentioned at the beginning, it can be provided that delays (for example 5.8 m / s², 2.9 m / s², 1.5 m / s²) which can be predetermined as braking functions in the control unit 120 can be taken in automatically depending on the energy storage content. In this embodiment, FIG. 1 activates this braking function within the control unit by means of the signal S. Here too, the driver of the vehicle can be informed by the display device 135 whether such a braking function is currently active. In particular, a gradual relapse strategy is provided in the event of a brake failure. A "last" measure in the context of such a fallback strategy would be the automatic locking of the parking brake function when the vehicle speed is essentially zero. There is therefore an active assignment of the possible vehicle decelerations to the memory content of the energy store.

In summary, it should be noted that the availability of the braking functions for the respective vehicle is recognized by the control unit 120 as a result of the invention. The control unit only releases the brake functions if there is sufficient energy supply, the driver of the vehicle being informed acoustically and / or optically of the availability.

If an inadequate energy supply is detected, vehicle functions can be modified and / or blocked via signal S or via means 140 in order to counteract vehicle operation that is hazardous to driving safety and traffic.

Claims (12)

1. Device for controlling units which are arranged in the drive train of a motor vehicle with

• - Electrically operable, preferably one or two-motor rig, wheel brakes ( 160-163 , 170-173 ),
• - Control means ( 140 ), the functions ( 150 , 145 ) of at least one of the units which are arranged in the drive train and / or the function of the wheel brakes control or regulate and which in response to a supplied signal (S) the potential of at least one affect these units,
• - At least one electrical energy storage means ( 100 , 101 ), which is operationally connected to the electrically operable wheel brakes to supply them with energy,
• - Diagnostic means ( 110 , 111 , 112 , 120 ) by means of which the potential of at least one of the energy storage means ( 100 , 101 ) is detected and which depending on the detected potential of at least one of the energy storage means generate the signal (S) in such a way that the potential of at least one of the units arranged in the drive train is adapted to the detected potential of at least one of the energy storage devices in a manner that is oriented to driving safety and / or the function of the wheel brakes for applying a prespecific braking effect is influenced.

2. Device according to claim 1, characterized in that the potential of the energy storage means ( 100 , 101 ) is represented by the energy state of charge of the energy storage means, it being provided in particular that the diagnosis means ( 110 , 111 , 112 , 120 ) at least two different energy states of charge the energy storage means ( 100 , 101 ) it grasp and the generated signal (S) represents the different energy charge states. 3. Device according to claim 1, characterized in that the potential of at least one in the drive train th unit by the drive power and / or by the Driving torque of the vehicle, especially by the maximum possible drive power and / or by the maximum possible che drive torque of the vehicle is represented. 4. The device according to claim 1, characterized in that at least one vehicle in the drive train of the vehicle motor, in particular an internal combustion engine, a clutch, a gearbox, a retarder and / or an exhaust valve are featured see is. 5. The device according to claim 1 or 4, characterized net that the potential of at least one in the powertrain arranged unit to the detected potential at least one Nes of the energy storage means is adjusted so that Support the braking effect of the vehicle at least one the units arranged in the drive train so affected flows that this has a braking effect on the vehicle is achieved. 6. The device according to claim 1, characterized in that the control means ( 140 ) are designed such that, depending on the signal (S), the function ( 145 ) of at least one of the units arranged in the drive train, in particular the vehicle engine, is influenced in such a way, that starting the vehicle, in particular starting the vehicle engine, is prevented, it preferably being provided that the starting of the vehicle engine is prevented by blocking the corresponding position of a travel switch. 7. The device according to claim 1, characterized in that the control means ( 140 ) are designed such that when the signal (S) represents a potential of at least one of the energy storage means, which is not sufficient to start the drive train arranged in the vehicle engine, a start of the vehicle engine is prevented, in particular it is provided that the prevention of the start of the vehicle engine is achieved by locking the corresponding position of a travel switch. 8. The device according to claim 1, characterized in that the electrically operated wheel brakes different loading drive functions, such as service brake function, Auxiliary brake function or parking brake function, the individual depending on the generated signal (S) Operating functions are released. 9. The device according to claim 1, characterized in that the control means ( 140 ) are designed such that in response to the signal (S)

• - The function ( 150 ) of at least one of the units arranged in the drive train, in particular the vehicle engine, is influenced such that the vehicle speed is set in a predetermined manner and / or
• - The function of the wheel brakes is influenced such that, depending on the signal (S) predeterminable vehicle delays are set automatically.

10. The device according to claim 9, characterized in that

• - The setting of the vehicle speed in the sense of a limitation to higher vehicle speeds occurs or
• - The setting of the vehicle speed happens such that the maximum vehicle speed is gradually reduced, the setting preferably depending on the signal (S) represented by the potential of the energy storage means ( 100 , 101 ) and in particular the limitation and / or the Reduction depends on the potential represented by the signal (S).

11. The device according to claim 1, characterized in that the electrically operated wheel brakes as electromechanical cal, hydraulic or pneumatic brake is formed. 12. A method for controlling units, which are arranged in the drive train of a motor vehicle, with electrically actuated wheel brakes ( 160-163 , 170-173 ) and at least one energy storage means ( 100 , 101 ), the energy supply with the electrically actuated, preferably one or two engine designed, wheel brakes ( 160-163 , 170-173 ) is operationally linked , whereby

• - The potential of at least one unit arranged in the drive train is influenced in response to a supplied signal (S),
• - the potential of at least one of the energy storage means ( 100 , 101 ) is detected,
• - Depending on the detected potential of at least one of the energy storage means, the signal (S) is generated in such a way that the potential of at least one in the drive train of an ordered unit is adapted to the detected potential of at least one of the energy storage means in a safety-oriented manner.