Patent Application
20220185251
The present disclosure relates to an electropneumatic brake system for a utility vehicle.
Service brake systems, in particular electronic brake systems (EBS), generally have a central electric brake control device, which can modulate braking processes on the front and rear wheel brakes by outputting electrical service brake signals. In this case, in part, the use of a second brake control device or an auxiliary control device is provided, which can maintain an auxiliary braking mode or at least a rudimentary braking mode or service braking mode in the event of failure of the central brake control device, which is also referred to as fail operation braking system (FOBS).
In regular braking mode, the central brake control device can generally perform brake slip control on the individual wheel brakes. In a fail operation braking mode, however, such brake slip controls are generally no longer possible.
EP 0 133 287 B1 describes a hydraulic automatic brake system in which a wheel revolution rate sensor outputs a pulse width modulated sensor signal. Here, the front left wheel revolution rate sensor and the front right wheel revolution rate sensor, as well as the rear wheel revolution rate sensors, are connected to different control units.
The three control units are connected to each other, especially in the event of a fault.
However, it turns out that these are generally very specific solutions and in particular are not applicable to electropneumatic brake systems used in utility vehicles.
In an embodiment, the present disclosure provides an electropneumatic brake system for a utility vehicle. The electropneumatic brake system includes a front first brake cylinder and a front second brake cylinder on a front axle, the front first brake cylinder and the front second brake cylinder being configured to brake respective first and second front vehicle wheels. The electropneumatic brake system also includes a rear first brake cylinder and a rear second brake cylinder on a rear axle, the rear first brake cylinder and the rear second brake cylinder being configured to brake respective first and second rear vehicle wheels. The electropneumatic brake system additionally includes a central brake control device configured to output brake control signals for pneumatic pressurization of the front first and second brake cylinders and the rear first and second brake cylinders. The electropneumatic brake system further includes two front wheel revolution rate sensors and two rear wheel revolution rate sensors configured to sense respective wheel revolution rates of the first and second front vehicle wheels and the first and second rear vehicle wheels and further configured to output respective wheel revolution rate signals. Furthermore, the electropneumatic brake system includes a second brake control device configured to actuate, in an at least partially electric auxiliary braking mode, the front first and second brake cylinders and the rear first and second brake cylinders in event of failure of the central brake control device. The two front wheel revolution rate sensors and the two rear wheel revolution rate sensors are divided into a first wheel revolution rate sensor group and a second wheel revolution rate sensor group. The first wheel revolution rate sensor group is configured to output respective wheel revolution rate sensor signals to the second brake control device, which is configured to relay the respective wheel revolution rate sensor signals to the central brake control device. The second wheel revolution rate sensor group is configured to output its wheel revolution rate sensor signals to the central brake control device. The central brake control device is designed to electrically actuate a slip controller of the vehicle wheels. The second brake control device is designed to actuate an auxiliary brake slip controller of the brake cylinders with the respective wheel revolution rate sensor signals of the first wheel revolution rate sensor group in the event of the failure of the central brake control device.
Subject matter of the present disclosure will be described in even greater detail below based on the exemplary figures. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following:
The present disclosure provides an electropneumatic brake system for utility vehicles and a method for its operation or control, which allow a safe fail operation mode.
This disclosure provides an electropneumatic brake system and a method for controlling it. Furthermore, a vehicle with the electropneumatic brake system is provided, which in particular is provided for carrying out the method.
Thus, not only is a fail operation mode or an auxiliary braking mode provided for controlling the wheel brakes by the second brake control device in the event of electrical failure of the central brake control device, but in addition an auxiliary brake slip mode is provided by means of the second brake control device. For this purpose, the four wheel brake number sensors of the two wheels of the front axle and the two wheels of the rear axle are divided into two wheel revolution rate sensor groups, each of which is read by the central brake control device or the second brake control device. In particular, direct signal lines between the wheel revolution rate sensors and the respective brake control device are provided for this purpose, which—in the usual way—ensure high signal transmission reliability.
Due to the direct signal lines, redundant forwarding of a wheel revolution rate sensor signal from a wheel revolution rate sensor to both control devices is generally not possible without the additional hardware complexity, for example branching cables (Y-cables). In order to avoid such branching cables or the use of dual wheel revolution rate sensors on the individual vehicle wheels, the wheel revolution rate sensors are divided into the two wheel revolution rate sensor groups. Thus, no additional hardware complexity is incurred due to special branching cables or dual wheel revolution rate sensors.
The second brake control device not only allows a redundant brake control mode (auxiliary braking mode) by controlling the wheel brakes in the event of electrical failure of the central brake control device, but in addition preferably a redundant brake slip control mode by estimating the wheel revolution rates of the wheel revolution rate sensors of the other wheel revolution rate sensor group, which it does not read directly. In this case, in particular, an estimation of the wheel revolution rate sensors by a wheel revolution rate sensor of the same axle may be provided, for example an estimation of the right front wheel revolution rate sensor by equating the left front wheel revolution rates and right front wheel revolution rates. For this purpose, in particular, an embodiment with a crosswise configuration of the wheel revolution rate sensors may be provided so that the left front wheel revolution rate sensor and the rear right wheel revolution rate sensor are assigned to a first wheel revolution rate sensor group and the other two wheel revolution rate sensors are assigned to the other wheel revolution rate sensor group. This embodiment thus allows a direct estimation of the remaining wheel revolution rates.
According to an alternative embodiment, the two front wheel revolution rate sensors can be included together with one of the two rear wheel revolution rate sensors in one of the wheel revolution rate sensor groups, so that the other rear wheel revolution rate sensor remains in the other wheel revolution rate sensor group. This is based on the consideration that the rear wheel revolution rates can in principle be estimated from the revolution rates of a transmission output shaft, since in a utility vehicle in general the wheels of the rear axle are driven and thus a transmission output shaft, which is sensed by a transmission controller, delivers corresponding revolution rates of the transmission output shaft, from which the wheel revolution rates can be estimated accordingly.
Thus, in particular, the wheel revolution rate sensor group of the central brake control device can receive the two front wheel revolution rates and one of the two rear wheel revolution rates, so that problems for example in the direct data connection between the brake control devices lead to a relatively low functional impairment, since the central brake control device has already read three of the four wheel revolution rates directly.
Furthermore, the wheel revolution rate sensors can also be grouped axle-wise, wherein then the wheel revolution rates of the rear axle can again be estimated from the wheel revolution rates of a transmission output shaft if necessary.
Furthermore, an embodiment with side-by-side assignment of the wheel revolution rate sensors is possible, so that the left wheel revolution rate sensors of the front axle and rear axle are arranged in a wheel revolution rate sensor group and the two right wheel revolution rate sensors are arranged in the other wheel revolution rate sensor group.
Furthermore, in each of these embodiments, the second brake control device may be designed as an electric parking brake control device, or the electric parking brake control device already provided for an electric parking brake is used in addition as a second brake control device to ensure the redundant service braking mode or brake control mode. Here, the parking brake control device then reads the wheel revolution rate sensors of one of the two wheel revolution rate sensor groups. Such a design has some advantages; thus, the parking brake control device can actuate in particular so-called tristop cylinders with combined service brake cylinders and parking brake cylinders, wherein then a fail operation braking mode is generally guaranteed by inverse pneumatic actuation of the parking brake cylinders, i.e. by applying air to the parking brake cylinders for releasing the parking brake, and venting the parking brake cylinders for applying the parking brake to enable the auxiliary or redundant service brake system.
Here, accordingly, an—alternative or rudimentary—brake slip control is possible, by outputting corresponding pneumatic control signals to the parking brake cylinders of the respective brakes of the rear axle. Thus, in the auxiliary braking mode for example there is no pneumatic actuation of a wheel brake module of the rear axle by the second brake control device.
The two brake control devices are preferably equipped with separate power supplies, i.e. two non-mutually dependent voltage supplies, so that even in the event of failure of one of the power supplies, the other brake control device is still electrically supplied. For this purpose, two separate batteries can be provided in the vehicle, for example.
The brake slip control can be carried out in normal braking mode in particular by means of ABS shut-off valves. In particular, an ABS shut-off valve may be provided on the front axle before each wheel brake, which is electrically actuated directly by the central brake control device. When designed as an EBS, for example, a front axle brake modulator may have two proportional relay valves, which enable direct modulation of the analog brake pressure for the respective side from a connected compressed air supply, depending on the received service brake signals of the central brake control device. The brake slip control is thus carried out by the downstream ABS shut-off valves. In the event of failure of the central brake control device, the auxiliary brake slip control can thus be carried out by the pneumatic auxiliary controller of the second brake control device, which is carried out for example via an upstream bypass valve, which is actuated as an electromagnetic valve by the second brake control device and for example can modulate an analog brake control pressure directly from a connected supply pressure. Thus, the brake control mode and accordingly also the alternative brake slip control are carried out via such a bypass valve.
On the rear axle, brake slip control can preferably be carried out by means of a rear axle brake module, which accordingly controls the ABS phases of pressure increasing, pressure holding and pressure reducing directly in the connected pneumatic brake lines to the wheel brakes. Here, the alternative brake control can be carried out by means of a rear bypass valve, which is electrically actuated by the second brake control device and for example in turn modulates an analog brake pressure value direct from the connected supply pressure. The analog brake pressure value can be output to the rear axle brake module, which passes this analog brake pressure value to the rear wheel brakes in the event of a fault. Thus, here too, an alternative or rudimentary brake slip control can be carried out directly by modulating the corresponding analog brake pressure value.
With the advantageous design of the second brake control device as a parking brake control device, such a rear bypass valve can be omitted, since the parking brake control device directly actuates the pneumatic parking brake cylinders and thus can perform an inverse braking mode, which thus enables the service brake function and the brake slip control function.
Accordingly, both brake slip controls for the ABS case and wheel revolution rate controls for vehicle dynamics control can be performed in order to enable instabilities due to asymmetric actuation of the wheel brakes.
The direct data connection between the two control devices may in particular be a bus line, which is provided in particular to be connected directly to only these two control devices separately from other control devices.
The wheel revolution rate sensors can be active or passive without any functional limitations here.
According to
The electropneumatic brake system 2 has a central electronic brake control device 3 (ECU-EBS), a brake pedal 4 for operation by the driver, a front axle brake module 5 for actuating a left front brake cylinder 6-1 via a first ABS shut-off valve 7-1 (ABS solenoid valve) and correspondingly for actuating a front right brake cylinder 6-2 via a front right ABS shut-off valve 7-2; furthermore, the electropneumatic brake system 2 correspondingly has a rear axle brake module 15 for controlling a rear left brake cylinder 6-3 and a rear right brake cylinder 6-4.
The more detailed design of the brake modules 5, 15 and brake cylinders 6-i, i.e. 6-1, 6-2, 6-3 and 6-4, can be carried out differently. According to the embodiment shown, the electropneumatic brake system 2 can be designed here as an EBS brake system or electronic brake system, which thus allows a direct brake pressure modulation on the axles VA, HA. According to the embodiment shown, the front axle brake module 5 may in particular have a proportional control valve and may receive compressed air from a second compressed air circuit or a second compressed air supply PS2 and may modulate at the two front brake cylinders 6-1,6-2 via the ABS solenoid valves 7-1, 7-2. In this case, according to the embodiment shown, for example a pneumatic fallback level is provided by a pneumatic connection 8 between the brake pedal 4 and the front axle brake module 5, which here additionally has a select-high valve 9, which will be discussed later.
The central electronic brake control device 3 receives a driver brake signal S1, and also if appropriate brake demand signals S2 from other controllers or control devices of the utility vehicle 1, for example an Autonomous Driving ECU 11, via a vehicle-internal first data bus, in particular a CAN bus 10.
Furthermore, for example, vehicle dynamics control or stability control may be provided in the electronic central brake control device 3 itself or may be transmitted or requested as an external brake demand signal S2 to the central brake control device 3.
On the rear axle HA, the rear axle brake module 15 can also additionally control the ABS control, for example as shown. Furthermore, the rear brake cylinders 6-3, 6-4 can also additionally implement the parking brake function, i.e. for example may have an additional pressure chamber for releasing a spring-preloaded wheel brake.
Other designs of the ABS shut-off valves and brake modules on the rear axle HA and front axle VA are also possible.
Furthermore, in the design shown here no pneumatic fallback level is directly provided for the rear axle HA; however this may also be provided correspondingly.
A wheel revolution rate sensor 12-i, i=1 to 4 is provided on each of the vehicle wheels VA-1, VA-r, HA-1, HA-r, i.e. a front left wheel revolution rate sensor 12-1 on the left front wheel VA-1, correspondingly a front right wheel revolution rate sensor 12-2 on the right front wheel VA-r, and correspondingly rear wheel revolution rate sensors 12-3, 12-4 on the rear wheels HA-1, HA-r. The wheel revolution rate sensors 12-i can be passive, i.e. delivering signals in the event of movement of the vehicle wheels, or also active, i.e. in particular also performing active measurement and for example delivering digital signals.
Here, the wheel revolution rate sensors 12-i are divided into two groups 14A and 14B, wherein this division is carried out differently in the different embodiments as explained below. The first group 14A is formed in the embodiment according to
In the embodiment of
The two brake control devices 3, 20 are connected via a direct data connection 16, for example a direct data bus or a serial data line. Advantageously, this direct data line 16 is different from the central vehicle bus or CAN bus 10.
Thus, the central brake control device 3 first detects the wheel revolution rate signals S12-2, S12-3; furthermore, the second brake control device 20 detects the wheel revolution rate signals S12-1, S12-4 and subsequently sends them via the direct data line 16 to the central brake control device 3.
According to
In a conventional manner, a trailer control module 30 is connected to the third supply circuit III. An electrical connection of the trailer 40 indicated here can be made via a trailer control line 41, i.e. a corresponding data connection according to ISO 11992 from the central brake control device 3.
Thus, in the brake system 2 of the embodiment of
Thus, in the normal mode, the second brake control device 20 is only used for reading one of the two wheel revolution rate sensor groups, here the first group 14A, and for communication with the (first) central brake control device 3; in the event of a complete or partial failure of the first brake control device 3, a replacement control mode or an auxiliary control mode or a redundant control mode of this electropneumatic brake system 2 or the brake cylinders 6-1, 6-2, 6-3, 6-4 is carried out by the second brake control device 20.
The power supply of the two brake control devices 3 and 20 is carried out separately: A power supply device 32 has two separate power supplies 32A and 32B, which for example each provide a supply voltage U1 or U2 of 24 V, wherein alternatively supply voltages U1, U2 of 12 V can be provided. Here, advantageously, separate batteries are provided in the utility vehicle 1. Thus if the first power supply 32A fails, for example, the second power supply 32B is still present, which supplies the second brake control device 20 with voltage or current, thus maintaining the redundant auxiliary brake control mode.
The electropneumatic brake system 2 not only enables a redundant brake control mode, but also redundant brake slip control. If for example the wheel revolution rate signals S12-1, S12-3 fail, since for example the second brake control device 20 is defective or not operational due to a lack of power supply, the first, central brake control device 3 can estimate the missing wheel revolution rates; in particular it can first be assumed with this crosswise arrangement that the wheel revolution rates on each axle VA, HA are the same on the left and right to realize an auxiliary or rudimentary failure case brake slip control (fail operation brake system, FOBS). This is particularly possible for ABS slip control
According to
Furthermore, the rear bypass valve 23 between the parking brake control device 120 and the rear axle brake modulator 15 is omitted, since the parking brake control device 120 actuates the rear brake cylinders 6-3, 6-4 in the form of tristop cylinders 116 via pneumatic parking brake control lines 113, 114. Thus, in the event of failure of the central brake control device 3 the redundant brake control mode or the service braking mode can be maintained by means of pneumatic actuation signals of the parking brake control device 120 via the pneumatic parking brake control lines 113, 114; this pneumatic auxiliary mode thus provides for an inversion of the pneumatic signals to the spring chambers or parking brake cylinders 106-3, 106-4 of the rear brake cylinders 6-3, 6-4 in the form of tristop cylinders 116, so that the parking brake chambers are vented to apply the service brakes or the service brake function, and the parking brake chambers are pressurized to release the service brake function.
Thus, the second embodiment with the pneumatic brake system 102 according to
The embodiment of
Here too, in the event of failure of the central brake control device 3 or its first power supply V1, the second brake control device 20—corresponding to the first embodiment of
Furthermore, a fail operation slip control mode is also possible with this embodiment of
As already explained, the embodiments of
The fourth embodiment of
In a fail operation slip control mode, in principle, the absent wheel revolution rates of the rear axle HA can be estimated from the transmission output shaft revolution rate signals S40, corresponding to the embodiment of
While subject matter of the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Any statement made herein characterizing the invention is also to be considered illustrative or exemplary and not restrictive as the invention is defined by the claims. It will be understood that changes and modifications may be made, by those of ordinary skill in the art, within the scope of the following claims, which may include any combination of features from different embodiments described above.
The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2019 106 243.8 | Mar 2019 | DE | national |
This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2020/055663, filed on Mar. 4, 2020, and claims benefit to German Patent Application No. DE 10 2019 106 243.8, filed on Mar. 12, 2019. The International Application was published in German on Sep. 17, 2020 as WO 2020/182569 under PCT Article 21(2).
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/055663 | 3/4/2020 | WO | 00 |
