Patent Application
20100252378
The invention relates to a control device for a brake system of a utility or commercial vehicle, wherein the brake system includes service brake cylinders and spring brake cylinders for braking the utility vehicle, an electronic control device, sensors for sensing the state of movement of the utility vehicle, a foot brake valve for activating the service brake, a manual control unit by which driver requests which are dependent on the method of activation of the manual control unit can be transmitted to the electronic control device, a module having electrically actuable valves for an anti-lock brake system and a module having electrically actuable valves for an electrically controlled parking brake.
Furthermore, the invention relates to a method for controlling a brake system for a utility or commercial vehicle which can be coupled to a trailer, having service brake cylinders and spring brake cylinders for braking the utility vehicle, an electronic control device, sensors for sensing the state of movement of the utility vehicle, a foot brake valve for activating the service brake, a manual control unit by which driver requests which are dependent on the method of activation of the manual control unit are transmitted to the electronic control device, a module having electrically actuable valves for an anti-lock brake system and a module having electrically actuable valves for an electrically controlled parking brake having a pneumatic control connection which can be coupled to a control inlet of a trailer control module.
Brake systems for utility or commercial vehicles are generally subject to strict regulations concerning fail safety and operational safety. Particular emphasis is usually placed here on redundancy of the service brake circuits in order to be able to reliably bring the utility vehicle to a stop even in the event of a defect. Furthermore, the intention is to make available a parking brake which is as failsafe as possible, in order to reliably prevent the vehicle from unintentional rolling away. Further partially electronically controlled driving safety systems such as ABS, ESP, etc. have become conventional depending on the purpose of use of the utility vehicles. As a result it is possible, in particular in the case of lightweight, small utility vehicles, for there to be a situation in which it is necessary to install either highly integrated complete solutions, which exceed the desired safety features by far, or autonomous individual systems, which are specially adapted to the customer's requirements for the respective utility vehicles. An electronic brake system (EBS) constitutes such a highly integrated safety solution for a utility vehicle, which solution combines known driving safety systems such as ABS, ESP, etc. Continuous, pressure-load-dependent closed-loop control of the braking effect is performed for all the axes, in which case the closed-loop control circuit is closed both by way of pressure sensors and by use of wheel speed sensors. Furthermore, the trailer control, for example for anti-jackknifing braking, is carried out electrically.
It may be appropriate both to install a highly integrated driving safety system and to use autonomous systems, which possibly then do not have all the desired properties. Using a highly integrated driving safety system, which is usually installed only in large and heavy utility vehicles (such as Class 8 trucks) and can meet all customer's requirements, would generally not only increase the costs for the more lightweight utility vehicle but also the weight of the entire safety equipment can significantly increase the overall weight of the more lightweight utility vehicle and take up valuable installation space since it is also necessary to install components which are not required. The costs, the weight, and the installation space which is taken up, are less significant in the heavy utility vehicle since they make up only a fraction of the overall price, the overall weight, or the available space. In particular in the case of lightweight utility vehicles it may, on the other hand, be desirable to achieve savings in terms of weight and installation space by using autonomous systems.
EP 1 504 975 B1 describes a pressure-medium-operated brake system for a vehicle, wherein the transmission of signals for activating the parking brake is carried out electrically.
An object of the invention is to reduce the necessary components for integrating the driving safety systems which are desired in particular for a lightweight utility vehicle while increasing the fail safety. At the same time, the intention is to utilize as many as possible of the available synergies in terms of functionality, without adversely affecting the safety of the utility vehicle.
This and other objects are achieved according to the invention by providing a control device for a brake system of a utility vehicle, wherein the brake system comprises: service brake cylinders and spring brake cylinders for braking the utility vehicle, an electronic control device, sensors for sensing the state of movement of the utility vehicle, a foot brake valve for activating the service brake, a manual control unit by which driver requests which are dependent on the method of activation of the manual control unit can be transmitted to the electronic control device, and a module having electrically actuable valves for an anti-lock brake system and a module having electrically actuable valves for an electrically controlled parking brake. The electronic control device performs the influencing of both the anti-lock brake system and the electrically controlled parking brake. If the brake system of the lightweight utility vehicle has both an anti-lock brake system and an electrically controlled parking brake, a single electronic control unit can be used for both driving safety systems. The electronic control unit performs closed-loop control on the control system of the anti-lock brake system, and at the same time, controls the function of the electrically controlled parking brake. In this way, it is possible to dispense with an electronic control unit, which could otherwise constitute an additional source of faults. The driving safety system which is provided in this way can also be integrated into any desired utility vehicle independently of other components. In particular, the integration of an EBS is not a precondition. Furthermore, the ABS system can, in the case of brake boosting, now directly influence the parking brake by way of the common control device. This is advantageous since it then results in a time advantage over separate systems in which the ABS system can influence the parking brake only via a detour through the CAN bus.
There may advantageously be provision that the module having electrically actuable valves for the anti-lock brake system and the module having electrically actuable valves for the electrically controlled parking brake at least partially use common air pressure inlets and air pressure outlets. Combining previously separate inlets and outlets of the individual driving safety systems permits a saving in terms of pneumatic control lines, which are complex to mount and susceptible to faults.
Furthermore there may be provision that the module having electrically actuable valves for the anti-lock brake system at least partially prevents the spring brake cylinders from being ventilated if the parking brake is ventilated, wherein maximum pressure loading of the cylinder is taken into account. This measure prevents overloading of the wheel brake since otherwise as well as the spring force of the parking brake the ventilation by the service brake would also load the cylinders. Such a function can be implemented, for example, by use of an additional solenoid, referred to as a hold magnet, which is arranged in the ABS system.
It is advantageously possible to provide that the module having electrically actuable valves for the anti-lock brake system at least partially prevents the spring brake cylinders from being ventilated by the parking brake if the service brake is already activated, wherein maximum pressure loading of the cylinder is taken into account. This measure also avoids overloading of the cylinders, wherein the force acting on the cylinders is held at a constant high level.
In order to reliably shut down the utility vehicle it is possible to provide that the parking brake can also be ventilated when the service brake is being ventilated, wherein maximum pressure loading of the cylinder is taken into account. The cylinder side of the parking brake is slowly ventilated here, while the service brake remains ventilated but the associated cylinder side is slowly vented in synchronism with the ventilation of the parking brake side, in order to avoid overloading of the cylinder.
It is advantageously possible to provide that the parking brake can be vented when the service brake is simultaneously activated, wherein maximum pressure loading of the cylinder is taken into account. This situation is typical during starting off. The function prevents the utility vehicle from rolling away while the maximum permissible cylinder pressure is maintained, wherein the pressures prevailing in the cylinder components are determined by way of sensors. The brake can then be enabled after the engine drive torque has been increased to the level of the braking torque, wherein additional torque is also requested by the CAN bus in order to avoid rolling away. In this context, the wheel speed sensors of the ABS system and of the tachograph are also taken into account.
In addition, it is possible to provide that the control device actuates the module having electrically actuable valves for the electrically controlled parking brake, such that when the spring brake cylinder of the utility vehicle is ventilated, the control line to the trailer is vented in order to test whether the traction vehicle can hold the entire train.
Furthermore, it is possible to provide that the trailer brake can be released by way of the manual control unit. It is advantageously possible to provide that the control device can go into a standby state when a wakeup signal is received. In the standby state, the parking brake can be opened or closed. It is also possible to provide that the ABS system and the electrically controlled parking brake operate only when the ignition is switched on.
Alternatively it is possible to provide that the ABS system and the electrically controlled parking brake begin to operate after the ignition is switched on, and after the ignition is switched off an oscillator-controlled run-on time occurs until the control device is at least partially deactivated.
Advantageously, the module having electrically actuable valves for the anti-lock brake system and the module having electrically actuable valves for the electrically controlled parking brake are arranged on a housing which accommodates the common electronic control device. This arrangement minimizes electric control lines from the electronic control device to the electrically actuable valves, which are present in the two modules, and from the pressure sensors, which are present in the modules to the electronic control device. This further increases the fail safety of the driving safety systems since the number of components which are susceptible to faults is reduced again.
The function of the anti-lock brake system and the function of the electrically controlled parking brake can be deactivated separately from one another. If the anti-lock brake system or the electrically controlled parking brake has a defect, a residual function can be maintained through the possibility of the separate deactivation of the faulty subsystem. As a result, the safety of the utility vehicle is improved.
A pneumatic control connection, which can be coupled to a control inlet of a trailer control module, is provided on the module for the electrically controlled parking brake, and the electronic control device can make available via the pneumatic control connection an anti-jackknifing braking function for the trailer if such anti-jackknifing braking is requested. The anti-jackknifing braking function prevents the trailer from reaching a higher speed than the utility vehicle since such a situation could ultimately lead to jackknifing of a vehicle train (tractor-trailer combination) composed of a utility vehicle and a trailer and therefore to a very unsafe driving situation. The utility vehicle can in this way be equipped with a further driving safety feature without additional complex assemblies having to be integrated. The trailer should advantageously be equipped here with wheel speed sensors and be connected to the CAN bus. The wheel speed information of the trailer is then transmitted to the control device and used to perform closed-loop control of the anti-jackknifing braking. The trailer is then not controlled electrically, as in the case of an EBS, but rather pneumatically.
A redundant voltage supply is provided for the electronic control device. The redundant voltage supply of the control device increases the fail safety of the driving safety systems since, in the event of a failure of one of the two voltage supplies of the electronic control device, the functionality of the driving safety systems is maintained.
It is advantageously possible to provide the electronic control device with a connection to a serial bus system. Modern utility vehicles usually have a large number of subsystems. These subsystems are usually connected to a serial bus system, such as the CAN bus, which is present in the utility vehicle, in order to exchange data with one another. For example, a trailer which is connected to the utility vehicle and to the CAN bus could have wheel speed sensors whose information, which relates to the wheel speed of the individual wheels of the trailer, could be transmitted via the CAN bus to the control device and could be used to perform closed-loop control of anti-jackknifing braking. Furthermore, it is contemplated that the load state of the utility vehicle is sensed and taken into account in the closed-loop control of the ABS.
Furthermore there may be provision for the vehicle acceleration measured values to be transmitted to the control device via the connection to the serial bus system.
The sensors of the brake system for sensing the state of movement of the utility vehicle include yaw sensors and the service brake cylinder pressure is subjected to closed-loop control as a function of the acceleration of the utility vehicle about the transverse axis and longitudinal axis. Modern ABS systems can also include additional vehicle-stabilizing functions such as roll-over prevention (RSP), that is to say a function for preventing the vehicle from rolling over, or an ESP function, that is to say a vehicle movement dynamics control system for avoiding skidding of the vehicle. In these functions, the brake cylinder pressure is also determined as a function of the measured accelerations of the vehicle about the transverse axis and the vertical axis. The measurement of the acceleration of the vehicle is carried out by the yaw rate sensors and the measured values are also fed to the control device. Yaw sensors sense the rotation of the utility vehicle about the utility vehicle axes. The rotation of the utility vehicle about the vertical axis is essential information for reducing the risk of the vehicle rolling over (RSP). The additional functions can be considered to be an extension of the conventional ABS functionality. Furthermore, in such a function the deviation of the average speed of the vehicle from the speed determined by the wheel speed sensors is taken into account.
There may advantageously be provision that the service brake cylinder pressure is subjected to closed-loop control as a function of at least one of the following variables:
parking brake cylinder pressure,
parking brake value signal generator pressure,
fault state of the system,
status of the foot brake value signal generator, and
speed of utility vehicle and wheel size.
Taking into account the system variables specified above provides further advantages in the implementation of the system according to the invention and permits more efficient closed-loop control of the system. For example, double pressure loading of the parking brake cylinders by the service brake can be avoided if a pressure, which is already applied, is taken into account together with the wheel size influences, for example, the speed of the utility vehicle which is determined by the rotational speed sensors, wherein the speed of the utility vehicle also determines the risk of rolling over for example.
Furthermore, the parking brake cylinder pressure is subjected to closed-loop control as a function of the handbrake value signal generator. This closed-loop control provides advantages, for example within the scope of an incremental parking brake.
The brake system makes the traction control system function available, wherein the electronic control device performs the closed-loop control of the traction control system. A traction control system is ultimately closely related to an anti-lock brake system and can therefore be integrated without further components into the control device and the modules which are arranged thereon and have electronically actuable valves.
According to a method for controlling a brake system according to the invention, the electronic control device initiates controlled anti-jackknifing braking using the module for the electrically controlled parking brake and, in particular, the control connection which is present, and monitors to determine if anti-jackknifing braking is requested. In this way, the advantages and particular features of the brake system according to the invention are also implemented within the scope of the method.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.
In the subsequent description of the drawings, identical reference signs denote identical or comparable components.
As a result of the interplay of the 3/2 way valve 300 with the 2/2 way valve 320, it is also possible to implement a test function for the utility vehicle by virtue of the fact that, specifically when the spring brake cylinder connection 270 is vented, the control inlet of the trailer control module which is connected to the control connection 370 is briefly ventilated via the control connection 370. The ventilation of this control inlet results in venting of the trailer brake system, with the result that the entire vehicle train has to be kept in this state by the utility vehicle, wherein the vented state of the spring brake connection 270 can be maintained by switching over the 2/2 way valve 320 in its pressure-holding position.
A further important task is performed by the 3/2 way valve 300 in respect of an anti-jackknifing braking function. Since the 3/2 way valve 300 is actuated in a pulse-width-modulated fashion by the electronic control device 60, selective pressure can be made available for the trailer control module at the control connection 370. In particular, the trailer can be braked independently of the braking of the utility vehicle, with the result that it is possible to prevent the trailer from colliding with the rear of the utility vehicle. Whether such anti-jackknifing braking is permitted depends on the driving state of the vehicle. Since the driving state is taken into account by the data which are received via the CAN bus and are acquired by the wheel speed sensors 220, safety-critical aspects, for example steering maneuvers, can be taken into account, and it can be ensured that pulse-width modulation of the 3/2 way valve 300 takes place only if the anti-jackknifing braking functionality is actually required, which greatly increases the service life of the 3/2 way valve 300. The checking as to whether the pulse-width modulation of the 3/2 way valve 300 is basically permitted is made dependent, inter alia, on the signals B, D, I, L, M and N. These signals characterize the following driving states of the vehicle or are derived from said driving states, for example through comparison with threshold valves:
B: Status of engine electronics,
D: Retarder status,
I: Speed less than threshold value,
L: Steering angle or differential wheel speed,
M: Status of accelerator pedal and engine brake, and
N: Measured speed of the ABS.
The information about the driving states can be obtained from a wide variety of sources. The speed of the vehicle can be obtained, for example, from the speedometer of the vehicle. Likewise, the wheel speed sensors of the anti-lock brake system can be used since the signals thereof are more precise at low speeds than that of the speedometer. In addition, speed values of the navigation system can be included in the calculations as absolute values. The torque of the engine is available, for example, within the scope of the engine control. Wheel speed sensors are present for the steering angle and the differential wheel speed, respectively. Basically, the signals can be obtained directly or via a data bus. With respect to the sensing of the inclination of the vehicle it is in particular also necessary to note that the latter can be sensed by means of a sensor system; however, the navigation information can also be made available by the navigation system.
The discussed signals, and under certain circumstances further signals or variables derived therefrom, are input into the control device 60. The electronic control device 60 then brings about the pulse-width-width-modulated actuation 400 of the 3/2 way valve 300 as a function of the received signals, wherein pulse-width-modulated actuation 400 can be prevented, in particular, if it is clear, on the basis of one or more of the information items fed to the control device 60, that anti-jackknifing braking should not take place. The module 64 contains a further electrically actuable 3/2 way valve 310 which is equipped as a bistable valve. This solenoid valve 310 supplies the control connection 370 of the module 64 with compressed air with the result that the illustrated electropneumatic module 64 can make available a control pressure for the trailer control module either on the basis of a monostable valve design, specifically by means of the 3/2 way valve 300, or a bistable valve design, specifically by means of the 3/2-way valve 310. The electropneumatic module 64 can therefore cope with various requirement profiles of the utility vehicle manufacturers.
A: Status of the manual control unit,
B: Status of the engine electronics,
C: Status of clutch,
D: Status of retarder,
E: Status of transmission,
F: Wheel speed of trailer,
G: Status of ECPB, and
H: Status of ABS
However, further connections to the control device 60 can be provided according to requirements.
The valve devices 62 and 64 are connected to the control device 60. In
In
The modules 62 which are shown in
Electronic braking force distribution (EBD),
Storage of the ABS events,
Brake diagnostics (BD),
Display of spinning rear axle wheels,
RSP for providing stabilization against rolling over, and
ESP for providing stabilization against rolling over and for providing yaw moment stabilization
Since the basic method of functioning and the design of an anti-lock brake system are generally known and are not essential for the invention, it is possible to dispense with a detailed explanation of the design and of the method of functioning of the module 62. Furthermore, the illustrated embodiment of the module 62 is to be considered only as one of the possible conventional embodiments of an anti-lock brake system. The individual module which is illustrated in
In addition to waking up the system by way of the wakeup switch, it is also contemplated to take into account signals via the CAN bus. For example, the system could be changed from an inactive state into an active state by switching on the ignition or by means of a general “wakeup” signal.
A connection 442 for the trailer to the CAN bus and a trailer control module 440 are also illustrated even though the latter could easily be integrated into the trailer itself. The brake system is capable of carrying out anti-jackknifing braking of the vehicle train via the connection between the control device 60 and the trailer control module 440 if such braking is requested by the driver.
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2007 037 346.7 | Aug 2007 | DE | national |
This application is a continuation of PCT International Application No. PCT/EP2008/006530, filed Aug. 7, 2008, which claims priority under 35 U.S.C. §119 from German Patent Application No. DE 10 2007 037 346.7, filed Aug. 8, 2008, the entire disclosures of which are herein expressly incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2008/006530 | Aug 2008 | US |
| Child | 12699640 | US |
