Calibration method of a braking system of at least one vehicle, calibration system, braking system and vehicle

Abstract

A calibration method of a braking system is described, comprising, among others: - measure a real electrodynamic braking force decay rate and a real electropneumatic force increase rate of an electropneumatic compensating braking force, determine a rate difference between the absolute value of the measured real electrodynamic braking force decay rate and the absolute value of the measured real electropneumatic force increase rate of the electropneumatic compensating braking force, and vary the value of the predetermined electropneumatic force increase rate so that the rate difference is zero; - measure a real decay start time of the electrodynamic braking force and a real activation time of the electropneumatic compensating braking force, determine a time difference between a real decay start time of the electrodynamic braking force and a real activation time of the compensating electropneumatic braking force, and vary the value of the predetermined expected activation time of the electropneumatic compensating braking force so that the time difference is zero. A braking system and a vehicle are also described.

Description

[0001] Calibration method of a braking system of at least one vehicle, calibration system, braking system, and vehicle

[0002] Technical sector

[0003] The present invention is generally in the field of braking systems and methods; in particular, the invention relates to a calibration method of a braking system of at least one vehicle, a calibration system, a braking system, and a vehicle.

[0004] Prior art

[0005] The following will describe the known art with special reference to the rail vehicle industry. However, what is described below can be similarly applied to vehicles in other industries.

[0006] In railway braking systems, it is a known art to use two braking systems, independent but in mutual interaction, called the electropneumatic braking system and the electrodynamic braking system.

[0007] The electropneumatic braking system may comprise both braking control and / or monitoring means (e.g., electronic control units and pneumatic / electropneumatic valves) and braking actuation means (e.g., brake cylinders and brake pads).

[0008] The electrodynamic braking system can also comprise both control and / or monitoring means (e.g., electronic control units) and braking actuation means (e.g., one or more electric motors).

[0009] As previously described, the electropneumatic braking system and the electrodynamic braking system interact, and the common purpose of this interaction is to apply a deceleration to the vehicle (e.g., rail vehicle or rail convoy) according to a braking request coming from a driver of the vehicle, called the "Driver," or coming from automatic braking request systems.

[0010] The interaction between the electrodynamic braking system and the electropneumatic braking system is such that the use of the electrodynamic braking system is favored over the electropneumatic braking system, as the electrodynamic braking system does not use the physical phenomenon of friction between two bodies (generating wear and tear) to produce a braking force, but employs magnetic fields within electric motors.

[0011] A further advantage of the electrodynamic braking system also relates to the possibility of converting, during a braking operation, the kinetic energy of the rolling stock into electrical energy, which is then fed back into a power grid.

[0012] However, the electrodynamic braking system typically fails to provide sufficient braking force during the entire braking duration. Thus, there is a velocity Vmin of the vehicle, below which the electrodynamic braking force is linearly reduced to zero. In this phase of linear reduction of the electrodynamic braking force, the electropneumatic braking force increases linearly, proportional to the reduction of the electrodynamic force.

[0013] The ultimate purpose of this phase, called the "fade" phase, is to apply a braking force 100 to the vehicle that is always congruent with the braking request coming from the vehicle driver or from the automatic braking request systems.

[0014] In other words, the electrodynamic braking force, decreasing to zero during the "fade" phase, is compensated by an increase in the electropneumatic braking force.

[0015] Such compensation, to occur properly, that is, without increase or decrease in the vehicle deceleration above or below the required deceleration, requires that the electrodynamic braking force and the pneumatic braking force be perfectly synchronized.

[0016] To achieve such synchronization, it is a known art to resort to the tuning of appropriate calibration parameters of the "fade" phase.

[0017] As can be observed in Figure 1, the start of the "fade" phase can be signaled by a FADE signal 102 that can take two values (e.g., 0 / 1), known to both the electrodynamic and electro pneumatic braking systems. Calibration parameters can be changed during the vehicle dynamic testing phase that precedes the vehicle commissioning phase.

[0018] Specifically, with reference to Figure 1, the calibration parameters of the "fade" phase are:

[0019] - a predetermined electropneumatic force increase rate (i.e., the slope determined by angle a) of a theoretical electropneumatic compensating braking force 106;

[0020] - a predetermined expected activation time t2 (in Figure 1), corresponding to an expected time that will elapse from the moment when the "fade" phase begins and the instant when the theoretical electropneumatic compensating braking force 106 takes on a value greater than zero, rising according to the predetermined electropneumatic force increase rate corresponding to the slope decreed by angle a.

[0021] From the graph in Figure 1, it can be deduced that, for optimal synchronization between the electrodynamic braking force and the electropneumatic braking force during the "fade" phase, the real electrodynamic braking force decay rate (i.e., the slope determined by the angle y) of the real electrodynamic braking force 104 must be equal to a real electropneumatic force increase rate of the electropneumatic compensating braking force corresponding to a slope determined by the angle P, but of opposite sign, of the real electropneumatic compensating braking force 108.

[0022] In addition, it is necessary to bring the real activation time h of real the electropneumatic compensating braking force to be equal to the real decay start time ti of the electrodynamic braking force , where:

[0023] • ta is the elapsed time from the moment when the "fade" phase begins and the instant when the real electropneumatic compensating braking force 108 begins to rise with a real electropneumatic force increase rate of the electropneumatic compensating braking force corresponding to the slope decreed by angle ;

[0024] • ti is the elapsed time from the moment when the "fade" phase begins and the instant when the real electrodynamic braking force 104 begins to decay with a real electrodynamic braking force decay rate corresponding to the slope decreed by the angle y. Time t2 and time ts are closely dependent on each other as they both relate to the electropneumatic braking system, and a change in time t2 has an impact on time t The reason for the existence of both times, t2 and tv stems from the fact that control of time t? is possible only by changing only the value t2, this being a parameter implemented, for example, within an electropneumatic braking control software. Thus, time T represents the reaction of the system against a target value t2.

[0025] Similarly, the predetermined electropneumatic force increase rate of the theoretical electropneumatic compensating braking force 106, corresponding to the slope due to angle a, and the real electropneumatic force increase rate of the real electropneumatic compensating braking force 108, corresponding to the slope due to angle P, are related to each other but it is only possible to act on the value of the predetermined electropneumatic force increase rate corresponding to the slope due to angle a, this being a parameter implemented within, for example, the electropneumatic braking control software. Thus, the increase rate corresponding to the slope due to angle represents the reaction of the electropneumatic braking system to a target slope value due to angle a.

[0026] The limitation of the known calibration solution is that this calibration of both the increase rate and the activation time (t2) relative to the theoretical electropneumatic compensating braking force 106 is performed manually by a qualified operator, based on his or her experience, during the tuning phase of the braking parameters.

[0027] Disadvantageous^, manual calibration, in addition to having a direct impact on the vehicle test phase (lengthening of test time), can be the cause of errors and / or the cause of suboptimal calibration.

[0028] In addition, since the above calibration is not automated but requires specific manual tests performed in the field, should further calibration be necessary during the life of the vehicle, it would be necessary to take the vehicle out of service.

[0029] Summary of the invention One purpose of the present invention is to provide calibration solutions for a braking system to reduce test time, reduce possible calibration errors, and improve calibration quality.

[0030] The above and other purposes and advantages are achieved, according to one aspect of the invention, by a calibration method of a braking system of at least one vehicle having the features defined in claim 1, according to a further aspect of the invention, by a calibration system having the features defined in claim 8, according to a third aspect of the invention, by a braking system having the features defined in claim 9, and according to a fourth aspect of the invention, by a vehicle having the features defined in claim 10. Preferred embodiments of the invention are defined in the dependent claims, the contents of which are intended to form an integral part of this description.

[0031] Brief description of the drawings

[0032] The functional and structural features of some preferred embodiments of a calibration method of a braking system of at least one vehicle, a calibration system, a braking system, and a vehicle according to the invention will now be described. Reference is made to the attached drawings, in which:

[0033] - figure 1 illustrates example graphs of a "fade" situation in which there is no synchrony between an electrodynamic braking force and the electropneumatic braking force;

[0034] - figure 2 illustrates example graphs of a "fade" situation in which, through a calibration method according to the present invention, the synchrony between the electrodynamic braking force and the electropneumatic braking force was found;

[0035] - figure 3 illustrates an example braking system according to the present invention;

[0036] - figure 4 illustrates a further example braking system according to the present invention.

[0037] Detailed description

[0038] Before explaining in detail a plurality of embodiments of the invention, it should be made clear that the invention is not limited in its application to the construction details and configuration of the components presented in the following description or illustrated in the drawings. The invention can be implemented in other embodiments and practically achieved in different ways. It should also be understood that phraseology and terminology are for descriptive purposes and should not be understood as limiting. The use of "include" and "comprise" and their variations are intended to comprise the elements enunciated below and their equivalents, as well as additional elements and their equivalents.

[0039] The following describes a first embodiment of a calibration method of a braking system of at least one vehicle, implemented by electronic control means.

[0040] For example, electronic control means can be or comprise at least one of the following: a computer, a controller, a processor, a microprocessor, a microcontroller, at least one PLC, and the like.

[0041] The braking system to which the calibration method can be applied comprises an electropneumatic braking system and an electrodynamic braking system.

[0042] The calibration method comprises the steps a) receive a braking request indicative of a target braking force; b) generate an electrodynamic braking force initially corresponding to said target braking force through said electrodynamic braking system.

[0043] The calibration method also comprises the following step: c) receive a braking force compensation request, indicative of the fact that said vehicle has reached a predetermined minimum speed and that said electrodynamic braking force will be decreasing and not sufficient to achieve said target braking force.

[0044] The braking compensation request can be considered equivalent to the "fade" signal described above with reference to a known art.

[0045] Following step c), the calibration method also comprises the following step: d) in response to the receipt of said braking force compensation request, apply an electropneumatic compensating braking force over time according to a predetermined expected activation time and a predetermined electropneumatic force increase rate, through said electropneumatic braking system.

[0046] For example, the predetermined expected activation time and predetermined electropneumatic force increase rate can be stored in storage means (e.g., a memory) comprised in, or associated with, the braking system.

[0047] In addition, the calibration method comprises the steps of: e) measure a real electrodynamic braking force decay rate and a real electropneumatic force increase rate of the electropneumatic compensating braking force; f) determine a rate difference between the absolute value of the measured real electrodynamic braking force decay rate and the absolute value of the measured real electropneumatic force increase rate of the electropneumatic compensating braking force; g) vary the value of said predetermined electropneumatic force increase rate so that said rate difference is zero.

[0048] For measuring the real electrodynamic braking force decay rate and the real electropneumatic force increase rate of the electropneumatic compensating braking force, respective sensor means, such as force sensors, can be provided.

[0049] Additionally, the calibration method also comprises the steps: h) measure a real decay start time of the electrodynamic braking force and a real activation time of the electropneumatic compensating braking force; i) determine a time difference between the real decay start time of the electrodynamic braking force and the real activation time of the electropneumatic compensating braking force;

[0050] 1) vary the value of said predetermined expected activation time of the electropneumatic compensating braking force so that said time difference is zero.

[0051] For example, one or more timing means, such as timers, can be provided for measuring the real decay start time of the electrodynamic braking force and the real activation time of the electropneumatic compensating braking force. For example, at the end of calibration, the changed value of the predetermined expected activation time and the changed value of the predetermined electropneumatic force increase rate obtained can be stored in the storage means (e.g., a memory) comprised in, or associated with, the braking system, replacing the previous values of the predetermined expected activation time and the predetermined electropneumatic force increase rate stored. In such a case, the method may comprise the additional steps of replacing the value of the predetermined expected activation time stored in the storage means with the varied value of the predetermined expected activation time and replacing the value of the predetermined electropneumatic force increase rate stored in the storage means with the varied value of the predetermined electropneumatic force increase rate.

[0052] Clearly, steps e), f), g) and steps h), i) and 1) can be carried out in different time orders. For example, steps e), f), g) can be carried out before steps h), i), 1), or vice versa. Or, steps e), f), g) can be carried out before steps h), i), 1).

[0053] Preferably, step g) may comprise:

[0054] - determine a rate change value by performing the division between said rate difference and the absolute value of the real electropneumatic force increase rate of the electropneumatic compensating braking force;

[0055] - vary the value of said predetermined electropneumatic force increase rate so that it takes on a value equal to the predetermined increase rate of the electropneumatic compensating braking force multiplied by the sum of 1 and the determined rate change value.

[0056] For example, the change value can be calculated according to the following formula: Change value = (|A| - |B|) / |B| where, |A| is the absolute value of the real electrodynamic braking force decay rate and |B| is the absolute value of the real electropneumatic force increase rate of the electropneumatic compensating braking force.

[0057] The change value can also be calculated as a percentage value, in which case, this change value can be calculated according to the following formula:

[0058] Change value % = 100*(|A| - |B|) / |B|

[0059] For example, the varied value of said predetermined electropneumatic force increase rate can be calculated according to the following formula:

[0060] C = C * (1 + Change value) where, C is the varied (i.e., calibrated) value of said predetermined increase rate of the electropneumatic compensating force, C is the predetermined electropneumatic braking force increase rate (i.e., the old value of increase rate, prior to calibration).

[0061] For example, starting from a % change value, the varied value of said predetermined electropneumatic force increase rate can be calculated according to the following formula:

[0062] C = C * (1 + Change value % / 100) where, C is the varied value of said predetermined increase rate of the electropneumatic compensating force, C is the predetermined electropneumatic braking force increase rate (i.e., the old value of increase rate present before calibration).

[0063] Preferably, step 1) may comprise:

[0064] - vary said predetermined expected activation time of the electropneumatic compensating braking force , so that the value of said predetermined expected activation time of the electropneumatic compensating braking force is equal to a value obtained by subtraction of said time difference from said predetermined expected activation time of the electropneumatic compensating braking force .

[0065] For example, the varied value of said predetermined expected activation time of the electropneumatic compensating braking force can be calculated according to the following formula: t = f - D where D is the time difference, t is the varied value of said predetermined expected activation time of the electropneumatic compensating braking force , and f is the value of the predetermined expected activation time of the electropneumatic compensating braking force (i.e., the old value present before calibration). Preferably, steps a) to 1) can be carried out after performing a verification that confirms that the vehicle is meeting predetermined test conditions.

[0066] Or, preferably, steps g) and 1) can be carried out after performing a verification that confirms that the vehicle has met predetermined test conditions while performing steps b) to f) and steps h) and i).

[0067] Preferably, verification that the vehicle is meeting predetermined test conditions comprises at least one of:

[0068] - verify that a forward speed of the vehicle corresponds to a test forward speed;

[0069] - verify that a load value of the vehicle corresponds to a test load value of the vehicle;

[0070] - verify that a value of adhesion between at least one vehicle wheel and a rolling surface corresponds to a test value of adhesion between at least one vehicle wheel and a rolling surface.

[0071] Preferably, steps a) to 1) can be carried out before the vehicle is put into service.

[0072] Preferably, steps a) to 1) can be repeated over time according to a predetermined calibration frequency.

[0073] In one example, preferably, the calibration method according to the present invention can apply to braking in which both the electrodynamic braking system and electropneumatic braking system are involved, in the absence of slipping conditions.

[0074] Slipping conditions can be defined as conditions for which at least one axle or wheel of the vehicle is slipping. For example, in the case of an axle to which two wheels are coupled, in the event of a slip, the linear peripheral velocity of the two wheels rigidly connected to the axle (calculated as the rotational speed of the wheels multiplied by the radius of the wheels) is less than the linear / forward velocity of the vehicle. The slipping condition can occur under conditions of low adhesion at the wheel / rail contact, a function of the presence of water, condensation, foliage, grease, oil, etc. In a further example, preferably, the calibration method according to the present invention can be applied to any type of load, constant during calibration, at any level of braking request, constant during calibration, at any initial and final speed of the vehicle and at zero gradient, or anyway within predefined tolerances, of track or segments of track, within which the calibration is performed.

[0075] In a further aspect, the present invention concerns a calibration system for a braking system comprising an electropneumatic braking system and an electrodynamic braking system.

[0076] Specifically, the calibration system comprises electronic control means arranged to perform a calibration method of a braking system of at least one vehicle according to any of the embodiments described above.

[0077] For example, the electronic control means can be or comprise at least one of: a computer, a controller, a processor, a microprocessor, a microcontroller, at least one PLC, and the like.

[0078] In yet another aspect, as observable in Figure 3, the present invention concerns a braking system. Such a braking system 300 comprises an electropneumatic braking system 302 and an electrodynamic braking system 304. In addition, the braking system comprises electronic control means 306 arranged to perform a calibration method of a braking system of at least one vehicle according to any of the embodiments described above.

[0079] For example, electronic control means can be or comprise at least one of: a computer, a controller, a processor, a microprocessor, a microcontroller, at least one PLC, and the like.

[0080] A further example of a braking system 300’ is shown in Figure 4. As observable in that figure, the electronic control means 306' arranged to perform a calibration method of a braking system of at least one vehicle are comprised in the electropneumatic braking system 302'.

[0081] In yet another aspect, the present invention relates to a vehicle comprising a braking system according to the embodiment previously described. For example, the vehicle may be a railway vehicle or a railway convoy comprising a plurality of railway vehicles.

[0082] For example, a vehicle referred to herein may be a locomotive or a wagon, and a path / track may comprise rails (rolling surface) on which the wheels of the locomotive roll. However, the embodiments described here should not be understood as limited to rail vehicles. For example, the vehicle may be a car, a truck (e.g., highway semi-trailer, mining truck, logging truck, or the like), or the like, and the route may be a road or a trail.

[0083] Thus, the benefit achieved is to have provided calibration solutions for a braking system that allow for reduced testing time, reduced possible calibration errors, and improved calibration quality.

[0084] An additional advantage concerns having provided automatic solutions for performing parameter calibration of the "fade" condition.

[0085] An additional advantage relates to providing solutions that allow for the calibration of the parameters of the "fade" condition without necessarily taking the vehicle out of service for intervention by a qualified operator.

[0086] Various aspects and embodiments of a calibration method of a braking system of at least one vehicle, a calibration system, a braking system, and a vehicle according to the invention have been described. It is understood that each embodiment can be combined with any other embodiment. Moreover, the invention is not limited to the described embodiments but may be varied within the scope defined by the appended claims.

Claims

CLAIMS1. Calibration method of a braking system of at least one vehicle, implemented by electronic control means, wherein said braking system comprises an electropneumatic braking system and an electrodynamic braking system; said calibration method comprising the steps of: a) receive a braking request indicative of a target braking force; b) generate an electrodynamic braking force initially corresponding to said target braking force through said electrodynamic braking system; c) receive a braking force compensation request, indicative of the fact that said vehicle has reached a predetermined minimum speed and that said electrodynamic braking force will be decreasing and not sufficient to achieve said target braking force; d) in response to the receipt of said braking force compensation request, apply an electropneumatic compensating braking force over time according to a predetermined expected activation time and a predetermined electropneumatic force increase rate, through said electropneumatic braking system; e) measure a real electrodynamic braking force decay rate and a real electropneumatic force increase rate of the electropneumatic compensating braking force; f) determine a rate difference between the absolute value of the measured real electrodynamic braking force decay rate and the absolute value of the measured real electropneumatic force increase rate of the electropneumatic compensating braking force; g) vary the value of said predetermined electropneumatic force increase rate so that said rate difference is zero; h) measure a real decay start time of the electrodynamic braking force and a real activation time of the electropneumatic compensating braking force; i) determine a time difference between the real decay start time of the electrodynamic braking force and the real activation time of the electropneumatic compensating braking force;1) vary the value of said predetermined expected activation time of the electropneumatic compensating braking force so that said time difference is zero.

2. Calibration method of a braking system of at least one vehicle according to claim 1,wherein step g) comprises:- determine a rate change value by performing the division between said rate difference and the absolute value of the real electropneumatic force increase rate of the electropneumatic compensating braking force;- vary the value of said predetermined electropneumatic force increase rate so that it takes on a value equal to the predetermined increase rate of the electropneumatic compensating braking force multiplied by the sum of 1 and the determined rate change value.

3. Calibration method of a braking system of at least one vehicle according to claim 1 or 2, wherein step 1) comprises:- vary said predetermined expected activation time of the electropneumatic compensating braking force , so that the value of said predetermined expected activation time of the electropneumatic compensating braking force is equal to a value obtained by subtraction of said time difference from said predetermined expected activation time of the electropneumatic compensating braking force .

4. Calibration method of a braking system of at least one vehicle according to any of the preceding claims, wherein said steps a) to 1) are carried out after performing a verification that confirms that the vehicle is meeting predetermined test conditions; or; wherein said steps g) and 1) are carried out after performing a verification confirming that the vehicle has met predetermined test conditions while performing steps b) to f) and steps h) and i).

5. Calibration method of a braking system of at least one vehicle according to claim 4, wherein said verification that the vehicle is meeting predetermined test conditions comprises at least one of:- verify that a forward speed of the vehicle corresponds to a test forward speed;- verify that a load value of the vehicle corresponds to a test load value of the vehicle;- verify that an adhesion value between at least one vehicle wheel and a rolling surface corresponds to a test adhesion value between at least one vehicle wheel and a rolling surface.

6. Calibration method of a braking system of at least one vehicle according to any of the preceding claims, wherein said steps a) to 1) are carried out before the vehicle is put into service.

7. Calibration method of a braking system of at least one vehicle according to any of the preceding claims, wherein said steps a) to 1) are repeated over time according to a predetermined calibration frequency.

8. A calibration system for a braking system comprising an electropneumatic braking system and an electrodynamic braking system, wherein said calibration system comprises electronic control means arranged to perform a calibration method of a braking system of at least one vehicle according to any one of the preceding claims.

9. A braking system comprising an electropneumatic braking system and an electrodynamic braking system, wherein said braking system comprises electronic control means arranged to perform a calibration method of a braking system of at least one vehicle according to any one of the preceding claims.

10. Vehicle comprising a braking system according to claim 9.

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