AU2013292777B2

AU2013292777B2 - Method for braking a combination of a plurality of vehicles coupled to one another

Info

Publication number: AU2013292777B2
Application number: AU2013292777A
Authority: AU
Inventors: Rainer Risse; Axel Stender; Markus Wolf
Original assignee: Wabco GmbH
Current assignee: ZF CV Systems Hannover GmbH
Priority date: 2012-07-19
Filing date: 2013-06-11
Publication date: 2016-08-11
Anticipated expiration: 2033-06-11
Also published as: AU2013292777A1; DE102012014408A1; EP2874855A1; EP2874855B1; WO2014012609A1; BR112015001183A2

Abstract

The invention relates to a method for braking a combination of a plurality of vehicles coupled to one another, wherein the vehicles each have electronically controlled brakes, particularly electropneumatic brakes, a stability system for detecting a tipping danger, at least one electronic switching unit ECU, and a data interface for receiving and transmitting data, and wherein if a tipping danger for one of the vehicles is detected, it is automatically braked, more particularly, the outer wheels on a curve are braked. According to the invention, if a tipping danger for one vehicle is detected, a signal is transmitted via the data interface, from which it can be seen that the stability system of the tipping-endangered vehicle is active, and the leading vehicle is then automatically braked.

Description

Method for Braking a Combination of a Plurality of Vehicles Coupled to One Another

TECHNICAL FIELD

The invention relates to a method for braking a combination of a plurality of vehicles that are coupled to one another. In addition the invention relates to a brake system for a vehicle.

BACKGROUND A reference herein to a matter which is given as prior art is not to be taken as an admission or a suggestion that the matter was known, or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

Road trains, consisting of a tractor vehicle and one or a plurality of trailer vehicles, are preferably fitted with an electropneumatic brake system, in which the driver of the tractor vehicle produces an electronic signal by operating the brake pedal, said signal being fed via a data interface to an electronic switching unit (ECU) and passing from there to modulators for operating electropneumatic brakes. Numerous safety functions are implemented in connection with wheel revolution rate sensors and other sensors present in the vehicle, e.g. for the determination of a lateral acceleration, e.g. an anti-lock brake system and a stability system for identifying a risk of tipping. The latter can not only be derived from the lateral acceleration, but also from wheel revolution rate measurements.

Trailer vehicles are also fitted with an ECU with a matching data interface and receive the brake signal of the tractor vehicle via the data interface. At the same time the trailer vehicle can influence or trigger independent braking operations with its own ECU and connected sensors and modulators, especially depending on locking wheels and in the event of an impending risk of tipping.

Vehicles that are provided for the European market are typically provided with the so-called CAN Bus for transferring data to a separate data line. Preferably one or a plurality of CAN routers thereby enable the transfer of data to more than one other vehicle and/or to a plurality of modulators as well as the power supply of connected brake devices. The latter are the ECUs for controlling the modulators for operating the brakes. In the North American market the so-called PLC bus (Power Line Carrier) has become established as the standard for the transfer of data in the vehicle. This involves a high frequency signal being transferred on an already present supply line. Both systems can be used to forward the brake signals and other data from ECU to ECU. A particular problem arises in connection with road trains that comprise two or more trailer vehicles. The trailer vehicles may have received different loads and/or have different centres of gravity. In turns and in critical driving situations there can be a risk of tipping for individual trailer vehicles without the danger being detectable in the tractor vehicle. Evasive manoeuvres are particularly critical in which steering occurs first in the one direction and then in the other direction at high speeds.

From US 7,971,942 B2 a brake system for road trains with two trailer vehicles is known, in which a brake signal is passed to other towed trailers when braking of the first trailer occurred because of a lack of stability. The regulation is ineffective in the event of a risk of tipping of the last trailer.

From WO 2008/114039 A1 a road train with two trailer vehicles is known, in which only one of the trailers is fitted with a system for independent braking, but the other trailer has at least an anti-lock brake system. The ECU of the independently braking trailer controls an ABS valve of the second trailer, e.g. in an unstable driving situation. Situation dependent, differentiated control of the brakes of the second trailer is thus not possible.

It is desirable to provide for the maintenance of the stability of the moving road train. In particular, the known methods are intended to be improved.

SUMMARY OF THE INVENTION

In one form of the invention there is provided method for braking a combination of a plurality of vehicles that are coupled to one another, wherein the vehicles each comprise electronically controlled brakes, a stability system for detecting a risk of tipping, at least one electronic switching unit (ECU) each and a data interface for receiving and for sending data, and wherein in the case of detecting a risk of tipping for one of the vehicles the latter automatically brakes, especially wheels on the outside of a turn being braked, wherein on detecting the risk of tipping for the one vehicle a signal is sent by means of the data interface indicating that the stability system of the vehicle at risk of tipping is active, and that one or a plurality of leading vehicles is/are then automatically braked; and wherein the leading vehicle is braked with lower brake pressure, only with up to 50% of the brake pressure of the vehicle at risk of tipping.

Throughout the description and claims of the specification, the word “comprise” and variations of the word, such as “comprising” and “comprises”, is not intended to exclude other additives, components, integers or steps.

On detecting the risk of tipping for one of the vehicles connected to the tractor vehicle, a signal is sent over the data interface that indicates that the stability system for the vehicle in danger of tipping is active. Moreover, one or a plurality of the vehicles ahead is then automatically braked. Once the stability system of the vehicle at risk of tipping is active, the ECU of said vehicle typically sends a standard message that indicates said activity. The message is referred to as "VDC active", wherein VDC stands for Vehicle Dynamic Control. A message sent over the CAN data interface has a so-called identifier that refers to the sender. Each vehicle ahead or its ECU can recognize from said message and from the identifier that the stability system in the following vehicle is active and according to the invention can brake its own vehicle depending on said message and on other parameters. For this purpose the ECU of the vehicle only has to be provided with suitable software. The necessary data for the method are available and are normally made available via the known data interfaces. Preferably, at least the vehicle immediately leading the vehicle at risk of tipping is braked. However, other leading vehicles can also be braked at the same time. Braking of only those leading vehicles that are not immediately in front of the vehicle at risk of tipping is also possible, e.g. the tractor vehicle or the first trailer vehicle in a road train with three trailer vehicles and a third trailer vehicle in danger of tipping.

Advantageously, only wheels of the leading vehicle that are on the outside of a turn are braked. This increases the stability of the leading vehicle and of the road train. All wheels of the leading vehicle can also be braked, however. A greater reduction in speed is thereby achieved, so that a stable state of the road train can be regained faster overall.

According to another idea of the invention, wheels of the leading vehicle that are on the outside of the turn are braked more heavily than wheels on the inside of a turn. This gives a good compromise between very rapid overall braking of the road train and increased stability of the leading vehicle.

According to the invention, the leading vehicle can be braked with a lower brake pressure than the vehicle at risk of tipping, especially only with up to 50% of the brake pressure of the vehicle at risk of tipping. This prevents the vehicle at risk of tipping from running into the leading vehicle.

The message indicating the active stability system of the vehicle at risk of tipping is advantageously transferred via the CAN bus to the leading vehicle and/or to other vehicles of the road train. Direct transfer to the tractor vehicle and transfer from there on to other trailer vehicles is also possible if said vehicles are leading the vehicle at risk of tipping. Alternatively, the signal can also be transferred via a PLC bus or a different data communications system. A brake system according to the invention comprises electronically controlled brakes, an electronic switching unit (ECU) for controlling the brakes, and a data interface for receiving the data of other vehicles, wherein the ECU brakes the vehicle if the data of a following vehicle signals a risk of tipping of the following vehicle and/or if the data of the following vehicle signals that its stability system is active, and wherein the leading vehicle is braked with lower brake pressure, especially only with up to 50% of the brake pressure of the vehicle at risk of tipping.

Finally, it is desirable to provide a vehicle with a corresponding brake system. In particular, it is a trailer vehicle. Fitting a tractor vehicle with the brake system is also possible however. The vehicle comprises, together with the electronic brake system or as parts thereof, an ECU, data lines for connecting to leading and following vehicles and preferably at least one CAN router or a comparable device for forwarding data.

BRIEF DESCRIPTION OF THE DRAWINGS

Moreover, further features of the invention are indicated in the description and in the claims. Advantageous embodiments of the invention are explained in detail below using figures. In the figures:

Fig. 1 shows a road train in which a rear trailer vehicle is braked in the region of wheels on the outside of a turn,

Fig. 2 shows the road train according to Figure 1, but in addition with a braking first trailer,

Fig. 3 shows a road train with a tractor vehicle and three trailer vehicles.

DETAILED DESCRIPTION A road train shown in Figures 1 and 2 consists of a tractor vehicle 10, a first trailer vehicle 11 and a second trailer vehicle 12. All vehicles comprise electropneumatic brakes and are fitted with an electronic brake system EBS. The electronic brake system in each vehicle includes at least one ECU, wherein the ECUs communicate with each other via a data interface. In vehicles for the European market, typically a CAN bus is provided for the transfer of data from vehicle to vehicle or from ECU to ECU. For other markets, other types of data transfer can be provided, e.g. a Power Line Carrier in vehicles for North America. In connection with the invention it is only relevant that there is a data link from ECU to ECU and thus signals or data can be transferred from vehicle to vehicle.

The electronic brake system EBS has a certain independence in the braking behaviour of each vehicle 10, 11, 12. Thus the EBS contains stability control and initiates independent braking measures for assisting and maintaining stable driving states. The risk of tipping when turning as a result of sudden evasive manoeuvres or for other reasons is particularly critical. As a result of different loading the vehicles can have different centres of gravity and respond differently in a driving situation. The vehicles also differ in their geometry and in their driving behaviour, also independently of the loading and centre of gravity.

The ECU provided in each vehicle preferably comprises a lateral acceleration sensor. A risk of tipping can be identified from the measured lateral acceleration values in connection with other data, e.g. axle load sensors or wheel load sensors. Axle loads or wheel loads can be read out in a simple manner by means of the pressures in pneumatic springs.

Moreover, a risk of tipping can be calculated using the data of already provided wheel revolution rate sensors that are not illustrated. The same are core components of an anti-lock brake system. By comparing the wheel revolution rates, possibly in connection with current brake pressures, it can be identified whether critical driving situations or even a risk of tipping exist when turning. In this case the EBS of the vehicle involved brakes the wheels on the outside of a turn. This case is shown in Figure 1 for the second trailer vehicle 12. There braking forces F are acting on outer wheels 13 against the direction of travel according to arrow 14. As a result of the braking of the outer wheels 13, the road train is slower overall and the risk of tipping is reduced. However, the braking effect is not optimal, because only about 14 % of the total number of wheels of the road train are braked.

In order to improve the braking effect, the EBS of the first trailer vehicle 11 leading the second trailer vehicle 12 responds and assists the braking. This is possible because in the event of the risk of tipping the ECU of the second trailer vehicle 12 not only activates its own brakes, but at the same time signals that the stability control is active to the other vehicles via the data link. Together with the signal, a so-called identifier is transferred, from which the vehicle that has sent the signal can be identified. The EBS in the first trailer vehicle 11 leading the unstable second trailer vehicle 12 responds to the received message and brakes the first trailer vehicle 11. The braking of the leading trailer vehicle 11 is a supporting measure for the preceding braking of the following second trailer vehicle 12 to reduce or eliminate the risk of tipping. The braking of the leading first trailer vehicle can therefore be referred to as derived braking. In the present case, the first trailer vehicle 11 comprises four groups of wheels, i.e. a front outer group of wheels 15, a front inner group of wheels 16, a rear outer group of wheels 17 and a rear inner group of wheels 18. The terms "inner" and "outer" refer to the turn currently being traversed by the road train, as above for the designation of the outer group of wheels 13 of the second trailer vehicle 12.

In the present case the groups of wheels 15 to 18 of the first trailer vehicle 11 are braked with equal force, at least if there is no risk of tipping for the first trailer vehicle 11. The brake pressure is selected here such that the second trailer vehicle does not collide. Preferably, the brake pressure in the leading trailer vehicle 11 is lower than in the trailer vehicle 12 or even only half as great. Nevertheless, significantly stronger braking results for the road train overall than only by the outer wheels 13 of the second trailer vehicle 12.

Alternatively, it can also be provided that only defined wheels are braked in the leading trailer vehicle 11, preferably the outer groups of wheels 15,17. In the configuration shown in Figure 2 with additional braking groups of wheels 15 to 18 on the first trailer vehicle 11, about 59% of the wheels present on the road train are braked. If only the outer groups of wheels 15, 17 are braked at the same time, even so about 37% of the wheels are braked.

It can also be provided that not only the vehicle immediately leading the unstable vehicle is braked at the same time, but that also other leading vehicles respond and brake independently. In this case it would be the tractor vehicle 10. In road trains with more than two trailer vehicles, other trailer vehicles could also brake at the same time. The minimum requirement for the function is only that the participating vehicles comprise an electronic brake system, can receive and send data via a data interface, and the ECUs comprise suitable software for carrying out the method.

Figure 3 shows an example of a road train with a tractor vehicle 19 and three trailer vehicles 20, 21,22. Only data links between the vehicles are shown, but not pneumatic lines present for the pneumatic brakes. An ECU 23 of the tractor vehicle 19 is connected by means of data lines 24, 25 to a CAN router 26 in the first trailer vehicle 20. Similarly, there is a connection by means of data lines 27, 28 from the CAN router 26 to a CAN router 29 in the second trailer vehicle 21. In the same way, a CAN router 30 in the third trailer vehicle 22 is connected by means of data lines 31,32 to the CAN router 29. Finally, a data line 33 extends from the CAN router 30 to the rear end of the third trailer vehicle 22. A data line 34, 35, 36 runs from each of the CAN routers 26, 29, 30 to an ECU 37, 38, 39 of the respective trailer vehicle. The ECUs 37, 38, 39 contain at least the functionality of a brake controller of the electronic brake system and control the operation of the brakes (not illustrated) of the respective trailer vehicle 20, 21,22 depending on the signals received by means of the data lines. Each trailer vehicle 20, 21,22 is thus provided with an ECU, a CAN router, data lines for connecting to leading and following vehicles and with further components of an electronic brake system.

The data lines are provided for the transfer of data according to ISO 11992 (CAN bus), likewise the CAN routers. These are therefore separate lines, separate from the usual high current cables for transferring electrical energy from vehicle to vehicle. In similar manner, however, data or digital signals can also be transferred and distributed on high current lines, e.g. according to the principle of the Power Line Carrier, as is known for vehicles provided for the North American market.

Each trailer vehicle 20, 21,22 can comprise a lateral acceleration sensor (not illustrated), especially within the respective ECU 37, 38, 39. If, for example, the ECU 38 of the second trailer vehicle 21 detects a risk of tipping because of the lateral acceleration or because of an analysis of wheel revolution rate sensors (not illustrated), the standard message "VDC active" is sent to the other vehicles 19, 20, 22 together with sender information by means of the CAN bus or the data lines. At the same time the ECU 38 controls brakes (not illustrated) of the second trailer vehicle 21, at least brakes on the outside of a turn. The leading trailer vehicle 20 for this purpose detects the braking operation of the following trailer vehicle 21 and the reason for this and operates its own brakes as a supporting measure, especially the brakes of the wheels on the outside of a turn or the brakes of all wheels. The braking force is thereby regulated in order to prevent the following trailer vehicles 21,22 from colliding. The last trailer vehicle 22 can likewise be braked at the same time in this case.

Because of the existing data link, still more leading vehicles, in this case the tractor vehicle 19, can also brake to provide assistance if this is desired.

Claims

The claims defining the invention are as follows:

1. Method for braking a combination of a plurality of vehicles that are coupled to one another, wherein the vehicles each comprise electronically controlled brakes, a stability system for detecting a risk of tipping, at least one electronic switching unit (ECU) each and a data interface for receiving and for sending data, and wherein in the case of detecting a risk of tipping for one of the vehicles the latter automatically brakes, especially wheels on the outside of a turn being braked, wherein on detecting the risk of tipping for the one vehicle a signal is sent by means of the data interface indicating that the stability system of the vehicle at risk of tipping is active, and that one or a plurality of leading vehicles is/are then automatically braked; and wherein the one or a plurality of leading vehicles is braked with lower brake pressure, only with up to 50% of the brake pressure of the vehicle at risk of tipping.
2. Method according to claim 1, wherein the electronically controlled brakes are electropneumatic brakes.
3. Method according to claim 1 or 2, wherein in the case of detecting a risk of tipping for one of the vehicles the latter automatically brakes wheels on the outside of a turn being braked.
4. Method according to any one of the preceding claims, wherein all wheels of the leading vehicle are braked.
5. Method according to any one of the preceding claims, wherein wheels of the leading vehicle on the outside of a turn are braked more strongly than wheels on the inside of a turn.
6. Method according to claims 1 to 3, wherein only wheels of the leading vehicle on the outside of a turn are braked.
7. Method according to any one of the preceding claims, wherein the signal is transferred by means of a CAN bus.
8. Method according to any one of the preceding claims, wherein the signal is transferred by means of a PLC bus.
9. Brake system for a vehicle for carrying out the method according to any one of the preceding claims.
10. Brake system for a vehicle, with electronically controlled brakes, an electronic switching unit (ECU) for controlling the brakes, and a data interface for receiving the data of other vehicles, wherein the ECU brakes the vehicle if the data of a following vehicle signals a risk of tipping of the following vehicle and/or if the data of the following vehicle signals that its stability system is active, and wherein a leading vehicle is braked with lower brake pressure, especially only with up to 50% of the brake pressure of the vehicle at risk of tipping.
11. Brake system according to claim 10, wherein the electronically controlled brakes are electropneumatic brakes.
12. Brake system according to claim 10 or 11 with a stability system for detecting a risk of tipping.
13. Vehicle with a brake system according to any one of claims 10 to 12.
14. A trailer vehicle with a brake system according to claim 13.