EP2547568B1 - Method and device for train length detection - Google Patents

Description

The present invention relates to a method and apparatus for train length detection in a train consisting of many cars, which is braked via a pneumatic brake system in accordance with the pressure in a coupled from car to car main air line HL in several braking stages whose pressure p _HL and flow V̇ and the ambient temperature T are detected sensor-technically along the time axis, from which the train length L is finally calculated by means of an electronic evaluation unit. Furthermore, the invention also relates to a method implementing device and a train in which such a device is installed.

• Hauptluftleitung HL und damit des gesamten Zugverbandes sind charakteristische Eigenschaften der Bremsanlage, wie beispielsweise die maximale Nachspeisung der Hauptluftleitung HL aufgrund der maximalen Leckage des Systems und der typischen längenabhängigen Durchschlagzeit, in welcher eine Änderung der Druckverhältnisse erkannt werden kann.

The main air line HL in train assemblies is used primarily for triggering the pneumatically operated brake, which come in the sense of a signal transmission by reducing the pressure in the braking position and are released when pressure increases. The main air line HL, which runs along all the wagons of a train, can also be used to obtain information about train-specific characteristics. It is thus possible to monitor the main air line HL with regard to train separation. Here, a check of the nachgespeisten volume flow and the pressure conditions during driving with brakes released, during braking and during the release is performed. Basis for the recognition of train separations or for the length recognition of the

• Main air line HL and thus of the entire train are characteristic features of the brake system, such as the maximum make-up of the main air line HL due to the maximum leakage of the system and the typical length-dependent breakdown time in which a change in pressure conditions can be detected.

These and other characteristic features of a pneumatic brake system are preferably based on standardized specifications of the main air line HL to allow a general applicability. Derived from these properties, threshold values and gradients are defined for the flow values and pressure values, which allow conclusions to be drawn about the train length or the continuity of the main air line HL via signal processing. For example, if it is found that the continuity of the main air line HL is not given, it can be inferred as a disturbing cause of this on a closed shut-off valve within the main air line HL between two cars.

From the DE 199 02 777 A1 is a technical solution for monitoring the train completeness, which emits a message about the condition of the train by means of a compressed air sensor and a flow meter for determining the volume flow in the main air line HL. The main air line of the train usually passes through all connected cars and can be monitored by sensors, for example, the relay valve on the traction unit, with the direction and amount of the volume flow of compressed air are measured by sensors known per se. Overall, there is a balance between inflow and outflow of air in the stationary state of the brake system. The incoming compressed air replaces only the leakage of air leakage from the brake system, which emerges over the entire length of the main air line HL. If it is braked, the air pressure in the main air line HL defined in most braking stages is lowered.

In order to monitor train completion, the measured values of the sensors monitoring the main air line HL are supplied to an electronic evaluation unit, which compares the detected measured values with predetermined values of the respective operating variables for a corresponding operating state of the train. Depending on the result of the comparison, it is concluded that the train is complete. In this case, the evaluation and acquisition of the measured values for determining the train integrity information takes place only at a single point of the train, preferably in the train of the train, so that other means for detecting operating variables of the main air line HL at other points of the train - especially at the train - are not required ,

However, this monitoring of train completeness has the disadvantage that at the same time it can not be determined precisely which train length is present at the same time. The knowledge of the train length is useful, for example, for the detection of so-called black cars. The order of the cars and the properties are usually known from a car list. Derived from the car list, the essential information for the driver, such as braking characteristics, compiled on a so-called brake note. Furthermore, the train length when driving on frequently traveled routes is important to comply with safety distances, for example.

Out DE 199 33 798 A1 is a method for train length detection, in which directly measured the length of the train and transmitted to the locomotive. For this purpose, volume and pressure signals in the main air line HL are determined by sensor technology, wherein in particular a timely transmission of information about the last car of the train follows the power tool. Subsequently, an evaluation device checks whether the volume and pressure signals and physical variables derived therefrom are known to a known setpoint range stored in the evaluation unit for the train length correspond. Depending on this, a signal is output which provides the information as to whether the measured values lie within the stored setpoint ranges. It is also proposed to determine the stored in the evaluation of the traction unit length of the train to be measured train of a Zuglängenmesser and to transmit to the traction unit. The train length can also be measured by an axle counter when starting or when leaving a station and transmitted to the locomotive. Thus, a stationary measuring device is activated here on the track for Zuglängenmessung.

All of these measures appear quite complex, since sensors placed outside the locomotive, namely in the last car or even outside the train, are used to obtain measured values for train length detection.

Out DE 100 09 324 A1 On the other hand, a method for engine-based determination of the train length of a train formation, in which only the physical state variables pressure, flow and temperature of the air in the main air line HL are measured in the region of the traction vehicle, from a defined sequence of about the driver's brake valve in the towing vehicle or other suitable actuators pressure changes in the main air line HL are generated, the associated flows temporally integrated and constant pressure - ie their steady state - determines the leakage rate and from these variables, the volume of the main air line HL is calculated, which can be deduced on the train length.

Although this calculation method takes into account the system-inherent leakage of the brake system, other disturbances, such as local vents in the area of the control valves associated with the individual brake cylinders of the carriages, are not taken into account during their acceleration. Because the control valves provide the braking acceleration in the first braking stage for a temporary additional ventilation of the main air line HL.

However, this measure leads to inaccurate measurement results in determining the train length.

From the DE 101 12 920 A1 a method for train integrity monitoring is known which uses a connected at the end of the train to the main air line pressure relief valve through which escapes at normal operating pressure always a certain amount of air per unit time. If the pressure in the main air line is lowered during braking, the pressure relief valve closes so that the volume flow decreases. This in turn indicates that the last car with the pressure relief valve is still carried. When the pressure is increased back to the normal operating pressure, the pressure relief valve returns to its open position and the increasing volume flow indicates that the last car is still being carried.

The DE 198 28 906 C1 discloses another method for checking the completeness of a train, in which pressure and flow values in the main air line are correlated with driving conditions and operator actions of the train driver. In this way, pressure changes initiated by the tractor operator are clearly differentiated from pressure changes resulting from sudden leakage of the main airline due to carriage breakage.

It is therefore an object of the present invention to provide a method and a device for train length detection, in which a precise length determination is possible only with zugverbinterner sensors.

The object is achieved on the basis of a method according to the preamble of claim 1 in conjunction with its characterizing features. The following dependent claims give advantageous developments of the invention. With regard to a device corresponding to the method, reference is made to claim 9. In claim 11, a train that contains this device is specified.

The invention includes the solution that the sensor-technical measured variable detection is carried out only from the stationary state of an existing brake stage I during the execution of the next brake stage II, until a stationary state within this braking stage II is reached again. By subsequently integrating the flow during the venting of the main air line HL to perform the next following brake stage II, the volume of the main air line HL is calculated taking into account the pressure prevailing in the initial and final state and the ambient temperature. From the volume calculated in this way, it is finally possible, in a manner known per se, to conclude the length of the main air line HL and thus the length of the train L given a known line cross-section. In this case, when previously determined at least once the volume (V) of the main air line (HL) as a correction value, the air volume (V), which is lost by Bremsbeschleunigungsverluste the individual brake cylinders (7) associated control valves (6) from the dissolved state of the brake system at computationally the determination of the train length (L) eliminated.

The volume can be determined concretely via the following formulaic relationship: $$V=\frac{T*p_n}{T_n}*\frac{{\displaystyle {\int }_{t1}^{t2}{V}_N*\mathit{dt}}}{\left|{\displaystyle {\int }_{t1}^{t2}{d}_p*\mathit{dt}}\right|}=\frac{T*p_n}{T_n}*\frac{{\displaystyle {\int }_{t1}^{t2}{V}_N*\mathit{dt}}}{\left|p\left(t_2\right)-p\left(t_1\right)\right|}$$

ergibt sich schließlich die Leitungslänge und damit die Zuglänge L des Zugverbandes. Der Querschnitt der Hauptluftleitung HL und der Kupplungen ist im Allgemeinen bekannt.Out $L=\frac{V}{Q}$

finally results in the line length and thus the train length L of the train. The cross section of the main air line HL and the couplings is generally known.

With the method described, the line length can thus be checked for each brake request which does not take place from the released state. This can be the Continuity of the main air line HL checked and a closed shut-off valve can be detected. If the cable length determination is integrated into the brake sample before the start of the journey, the system can issue a warning about a different train length compared to the information in the brake card. For example, if after the brake test other cars with a closed stopcock attached to the train, this error is detected when connecting the traction unit at the other end to change direction.

To detect the correct volume flow, the leakage must be considered in the above procedure. When decelerating from an existing braking stage, the main air line HL is vented completely, except for the leakage, via the driver's brake system, and thus detected by the flow measurement. The leakage rate must be added in addition to the volume flow. The following relationship applies: $$V_{N_{\mathit{total}}}=V_{N_{\mathit{measuring}}}+V_{N_{\mathit{leakage}}}$$

The leakage rate is dependent on the pressure level in the main air line HL. For the calculation, the leakage is regarded as a nozzle in the main air line HL with a constant nozzle cross-section, which vents against the atmosphere.

ergibt sich mit dem Durchflusskoeffizienten Y folgender Ausdruck: $$V_N=A*\frac{T_N}{p_N*T}*{\left(2*287*T\right)}^{0,5}*60*{10}^{-3}*Y*p_1$$

$$\left[\frac{l}{\min }\right]$$

mit A in mm² mit T_N = 293,15K und p_N = 1,013 barA, wobei gilt: $Y={\left(\frac{k}{k-1}*{\left(\frac{p_2}{p_1}\right)}^{\frac{2}{k}}-{\left(\frac{p_2}{p_1}\right)}^{\frac{k+1}{k}}\right)}^{0,5},$

wenn $\frac{p_2}{p_1}>0,528$

mit k=1,402, sonst Y=0,484. p₁ entspricht dabei dem Absolutdruck vor, p₂ dem Absolutdruck nach der Düse und T der Temperatur. Bei R = 287 $\frac{J}{\mathit{kg}*K}$

handelt es sich um die allgemeine Gaskonstante.From the volume flow V̇ = A * (2 * R * T ) ^0.5 * Y and the relationship $V_N=\frac{V*p_1*T_N}{p_N*T}$

with the flow coefficient Y, the following expression results: $$V_N=A*\frac{T_N}{p_N*T}*{\left(2*287*T\right)}^{0.5}*60*{10}^{-3}*Y*p_1$$

$$\left[\frac{l}{\min }\right]$$

with A in mm ² with T _N = 293.15K and p _N = 1.013 barA, where: $Y={\left(\frac{k}{k-1}*{\left(\frac{p_2}{p_1}\right)}^{\frac{2}{k}}-{\left(\frac{p_2}{p_1}\right)}^{\frac{k+1}{k}}\right)}^{0.5}.$

if $\frac{p_2}{p_1}>0.528$

with k = 1,402, otherwise Y = 0,484. p ₁ corresponds to the absolute pressure before, p ₂ the absolute pressure after the nozzle and T the temperature. At R = 287 $\frac{J}{\mathit{kg}*K}$

it is the general gas constant.

After determining the leak rate at a constant pressure level, the constant nozzle cross section A as a function of the temperature can thus be determined via the formal relationship [III]. V _{N leakage} can thus be calculated approximately from the measured pressure curve in the main air line HL.

An advantage of the method results from the measure that the air flowing into the main air line HL is ignored during the first filling of the brake system. Because when Erstauffüllen the air flows not only in the main air line HL, but also in the working chambers of the control valves and in various reservoirs of the car. In this case, the volume of the storage container of the individual carriages can vary, so that in practice a calculation-related correction of this disturbance variable is not possible. In addition, most of the initial state of the working chamber of the control valves and the reservoir is not known. The method completely excludes the measurement errors resulting therefrom. To solve this problem, the method provides in principle, the flow rate of the air only in the filled state, for example, after first filling while driving or in any stationary state of the main air line HL, in which the pressure p _{HL is} constant, is detected. By excluding the acceleration effect, the process avoids an unknown flow size, resulting in a more accurate measurement result.

According to a measure improving the invention, it is proposed that, to determine the train length during ventilation of the main air line HL, the sensor-technical measured variable detection is only carried out until the pressure of the supply air tank connected to the main air line is reached. During such Einleitungsbetriebs with standard brake designs so the evaluation of the filling process of the main air line to the onset of Vorratsbehälternachspeisung according to the method of the invention is possible. The flow rate is evaluated up to a pressure value below the reservoir pressure. In this process, the unknown reservoir size is advantageously excluded.

According to a measure which further improves the invention with regard to a precise measuring result, it is proposed that the cross-section of the line cross-section which is used with the determined volume of the main air line HL for calculating the train length is both the cross section of the main air line HL passing through the individual carriages and the cross section the interposed line couplings is taken into account. The train length L results - as stated above - from dividing the determined volume of the main air line HL by the line cross-section Q.

For computational compensation of the leakage as a further disturbance variable within the brake system, it is proposed that the volume flow thereby induced in the stationary state is additionally measured within the main air line HL, so that this measured variable can be used as a correction value for determining the train length for the computational elimination of the disturbance. The flow coefficient necessary for the calculation can be simplified in the range 0.45 to 0.5, if the pressure ratio p2 to p1 gives the value Y = 0.484 +/- 10%. Even with a ratio greater than this value, the error remains relatively low, since with decreasing pressure in the main air line HL and the leakage decreases. Is the leakage of the pneumatic Brake system calculated or fixed, can be obtained by inclusion in the calculation of the train length a qualitatively better result.

According to the invention, when the volume of the main air line HL has previously been determined at least once as a correction value, the air volume which is lost from the released state of the brake system by braking acceleration losses of the individual control valves associated with the brake cylinder is eliminated by computation during the determination of the train length. The inventive method is based on the fact that the acceleration effect of the control valves of the brake system to determine the length of the main air line HL are excluded. However, if the line volume is determined once only, for example in the course of a brake test before the departure of the train, the resulting error in now known volume can be determined. The reason for this is that during the train ride during braking, the train length can also be checked from the released state during brake requests in order to detect the demolition of a pulling part or a closed stopcock. Preferably, to carry out this measure, at least a pressure of about 0.1 bar should be vented via a nozzle until the acceleration effect in the individual control valves responds. The acceleration effect now draws approximately a pressure of 0.3 bar locally from the main air line HL. Then the effect is complete and the control valves are absolutely sensitive. By this connection, an approximate calculation of the amount of air lost as a result of the ideal gas equation is now possible. The following applies: $${\mathrm{p}}_{\mathrm{previously}}*{\mathrm{V}}_{\mathrm{previously}}={\mathrm{p}}_{\mathrm{after\; that}}*{\mathrm{V}}_{\mathrm{after\; that}}$$

According to another measure further developing the invention, the volume determination of the main air line HL can also take place in the so-called two-line mode. In two-line operation, reservoirs, which can vary in size, and other compressed air consumers via a separate compressed air line, the main reservoir line HB filled. The main tank line HB runs along the train in parallel to the main air line HL. Thus, the method according to the invention can also be used in the case of a two-pipe operation in the case of aeration after first filling because there are no unknown volume sizes. In other words, the determination of the volume of the main air line HL thus takes place during release of the brakes as a result of ventilation of the main air line HL.

The filling process of the main air line HL can be evaluated between any two stationary states via the method according to the invention for determining the train length. Since no acceleration effect occurs during the ventilation process, only the leakage must be taken into account as a disruptive factor. In contrast to the volume determination via the vent, in two-line operation, the leakage must be subtracted from the measured volume flow as a function of the pressure. So you get: $${\dot{V}}_{\mathrm{N\; total}}={\dot{V}}_{\mathrm{Nmess}}+{\dot{V}}_{\mathrm{Nleckage}}$$

As part of the sensor technology, two separate sensors 2b and 2b 'are provided for determining the flow rate V̇ in this embodiment. While the first sensor 2b is used during the changeover between the stationary states, ie during the transition from one braking stage to the next higher braking stage, the second sensor 2b 'is used only in the steady state for the purpose of leakage measurement. Since the change between stationary states produces a significantly higher flow rate V̇ , the first sensor 2b is dimensioned larger than the second sensor 2b ', which in contrast has only to determine very small flows V̇ . As a result of the different measuring ranges used as a result, the accuracy of the determination of the flows V̇ increases overall. However, a distinction must be made between single-line operation and two-pipe operation. In two-pipe operation, a sensor that measures both leakage and ventilation processes or two sensors with the same cross-section in series can be sufficient in the case of ventilation. The leakage sensor requires a smaller measuring range and can therefore achieve greater accuracy.

In the case of single-line operation with leakage measurement, two sensors are absolutely necessary or one device that allows bidirectional measuring since the flow during braking is opposite to the flow during the leakage measurement. Again, that the cross section of the main air line HL may not be narrowed and the leakage sensor requires a smaller measuring range and thus a higher accuracy can be achieved.

The electronic evaluation unit 4 takes into account both the cross-section of the running through the individual carriages la to 1c main air line HL and the cross section of the interposed line couplings 5 in determining the train length with respect to the line cross-section to achieve more accurate calculation results.

In each individual car la to 1c at least one control valve 6 is arranged with connected thereto pneumatic brake cylinder 7 for actuating the brakes.

For the purpose of braking acceleration also escapes air volume from the control valves 6, which can be detected as a correction value in order to consider this computationally when determining the train length.

According to FIG. 2 the train length detection is preferably carried out by starting from a stationary state of the brake system, which arises due to the applied braking stage I. First, a sensor-technical measured value detection of the physical values pressure p _HL , flow V̇ of the main air line HL and the ambient temperature T takes place, namely during the execution of the next brake stage II. Until a stationary state is set again.

Subsequently, the flow V er determined in this way is integrated , taking into account the initial and final states of the prevailing pressure p _HL and the ambient temperature T according to equation (I) given above. The result of calculation is the volume V of the main air line HL. From this, the calculation of the known line cross-section Q of the main air line HL also calculates its length, which corresponds to the length L of the train.

The invention is not limited to the preferred embodiment described above. On the contrary, modifications are conceivable which are included within the scope of the following claims. It is also possible to determine further disturbing influencing variables and to take them into account as correction values in order to realize precise train length detection.

LIST OF REFERENCE NUMBERS

1

dare

2

sensor

3

train

4

evaluation

5

line coupling

6

control valve

7

brake cylinder

8th

Air reservoir

HL

Main air line

HB

Main reservoir pipe

V

Volume of the main air line

Q

Cable cross-section of the main air line

p _HL

Pressure in main air line

V

Flow through the main air line

T

ambient temperature

L

train length

Claims (8)

1. Method for train length detection in a train formation consisting of many carriages (1a - 1c), which is braked via a pneumatic brake system in several braking stages in accordance with the pressure in a main air line (HL) looped from carriage (1a) to carriage (1c), the pressure (p_HL) and flow rate (V) of the main air line (HL) and the ambient temperature (T) being measured by sensor-technological means along the time axis, wherefrom the train length (L) is calculated by means of an electronic evaluation device (4), wherein the sensor-technological detection of measured variables is carried out from the stationary state of an existing braking stage (I.) during the next braking stage (II.) until a stationary state is once again reached, whereupon, by integrating the flow rate (V) during the venting of the main air line (HL) for carrying out the next braking stage (II.), the volume (V) of the main air line (HL) is calculated taking account of the pressure (p_HL) prevailing in the starting and the end state and of the ambient temperature (T), in order to determine therefrom, at a known line cross-section (Q), the train length (L) corresponding to the length of the main air line,
   characterised in that, if the volume (V) of the main air line (HL) has previously been determined at least once, the air volume (V) lost by brake acceleration losses of the individual control valves (6) assigned to the brake cylinders (7) from the released state of the brake system is eliminated computationally as a correction value in the determination of the train length (L).
2. Method according to claim 1,
   characterised in that, for determining the train length (L) during the ventilation of the main air line (HL), the sensor-technological detection of measured variables is carried out only until the pressure (p_HL) of the air reservoir (8) connected to the main air line (HL) is reached.
3. Method according to claim 1,
   characterised in that in the line cross-section (Q) both the cross-section of the main air line (HL) running through the individual carriages (1a - 1c) and the cross-section of the line couplings (5) located in between are taken into account.
4. Method according to claim 1,
   characterised in that, in the stationary state, the volumetric flow rate (V _Nleck) caused by leakage of the pneumatic brake system is measured in order to use this measured variable in the computational elimination of the disturbance variable as correction value in the determination of the train length (L).
5. Method according to claim 1,
   characterised in that, in a two-line operation, in which the compressed air users are charged via a separate main reservoir line (HB), while the main air line (HL) is exclusively used for braking, the volume (V) of the main air line (HL) is determined while the brakes are released as a result of the ventilation of the main air line (HL).
6. Method according to claim 5,
   characterised in that the correction value representing the leakage of the brake system is subtracted from the measured flow rate (V) as a function of the pressure (p_HL).
7. Device for train length detection in a train formation consisting of many carriages (1a - 1c), the pneumatic brake system of which brakes in several braking stages in accordance with the pressure in a main air line (HL) looped from carriage (1a) to carriage (1b), wherein sensors (2a - 2c) detect the pressure (p_HL) and flow rate (V) and the ambient temperature (T) along the time axis, wherefrom an electronic evaluation unit (4) calculates the train length (L), wherein the evaluation unit (4) carries out the sensor-technological detection of measured variables from the stationary state of an existing braking stage (I.) during the next braking stage (II.) until a stationary state is once again reached, in order to calculate, by integrating the flow rate (V) during the venting of the main air line (HL) for carrying out the next braking stage (II.), the volume (V) of the main air line (HL), taking account of the pressure (p_HL) prevailing in the starting and the end state and of the ambient temperature (T), in order to determine therefrom, at a known line cross-section (Q), the train length (L) corresponding to the length of the main air line,
   characterised in that the sensor (2b) is used for measuring the flow rate (V) of the main air line (HL) during the switch between the stationary states, while a second sensor (2b') of smaller dimensions is used for measuring leakage in a stationary state, and in that the electronic evaluation unit (4) is designed to eliminate, if the volume (V) of the main air line (HL) has previously been determined at least once, the air volume (V) lost by brake acceleration losses of the individual control valves (6) assigned to the brake cylinders (7) from the released state of the brake system as a correction value computationally in the determination of the train length (L).
8. Train formation consisting of many carriages (1a - 1c), each of which can be braked by a pneumatic brake system in accordance with a looped-through main air line (HL), comprising a device for train length detection according to claim 7.

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