PAPER

Improvement of Response and Efficiency of Railway Air System by Modifying Software for Control

Shin-ichi NAKAZAWA Daisuke HIJIKATA Brake Control Laboratory, Vehicle Control Technology Division

Air brake systems are essential for the safety operation of railway vehicles. However, a certain amount of time is required to distribute compressed air through the pipe so that the brake cylinders fill. It is considered a more efficient system would produce significant ben- efits for safety, robustness, saving energy and labor for maintenance and so on. This study therefore proposes a new method for reducing response time of the system for supplying the compressed air, by controlling wheel slide protection (WSP) dump valves installed in recent railway vehicles. Attempts were also made to reduce air consumption in the air braking system, focusing on cases where a WSP system is applied. The benefits of the new approach were verified through actual railway vehicle tests and hybrid simulation method, etc. Results demonstrated that the proposed method reduced the response time and air consumption, and improved braking performance.

Keywords: , air consumption, idle running time, wheel slide protection

1. Introduction Service brake command command Air compressor

Brake control unit Brake electric Main reservoir Recently, railway vehicle braking systems are designed control unit

to save energy and maintenance, leading to a preference (Air spring) Main reservoir pipe Electro-pneumatic Emergency Load weighing electro-magnetic for regenerative braking for electric railcars, and engine valve valve valve and hydro-dynamic for diesel railcars. However, Whistle system Double check considering the possibility of these brakes failing to func- valve

Supply Pantograph system tion effectively during a power outage or other emergency, Relay valve reservoir air brakes, which use compressed air to press frictional Lower pressure system (Supplied through another route) material onto wheel treads or brake discs to produce a WSP dump valve command Secuurity brake braking effect, are still considered an important system for reservoir Control air stopping completely and safely. reservoir WSP WSP WSP WSP WSP dump valve dump dump dump dump In this context, this paper discusses methods for im- valve valve valve valve device proving air brake response times and efficiency by upgrad- Door engine, etc.

ing the current software used in existing relevant vehicle to next car Brake cylinder systems. Specifically, this paper proposes one method for reducing the response time using WSP (wheel slide protec- Fig. 1 Standard compressed air system for railway ve- tion) dump valves and another method for reducing air hicles consumption through WSP control, to save energy. Nowadays, many railway vehicles are equipped with the electric command brake system, which uses a BCU 2. Air brake system for railway vehicles (Brake Control Unit) to convert driver inputs or electric command signals from the ATC, or other safety systems, Figure 1 illustrates an example of the standard com- into air pressure which is then distributed in the system. pressed air system for railway vehicles. Air generated by The BCU consists of a series of components including the the air compressor is stored in the main reservoir from followings: where the compressed air is supplied through main res- - A brake electric control unit, which sends and receives ervoir pipes to relevant equipment installed on the electric signals, computes braking force and fulfills other set including air brake, air springs for supporting vehicle functions. bodies, and door operating equipment. Use of compressed - A load weighing valve detects air spring pressure. air has been growing because of vehicle body tilting control - An electro-pneumatic valve and an emergency electro- and vibration damping systems for ride comfort, and with magnetic valve, both to send out compressed air based that, the volume of air required to operate these equipment on electric signals received. has been increasing. - A relay valve amplifies these pilot pressures before dis- The air brake system is equipped with supply reser- tribution. voirs and air reservoirs for the security brake, each with a The compressed air from the BCU is distributed to the dedicated check valve, to secure enough compressed air for and brake cylinders through piping in the vehicle braking in the event of the loss of main air reservoir pres- and further through the WSP dump valves near the bogies. sure due to train separation or other emergencies.

28 QR of RTRI, Vol. 58, No. 1, Feb. 2017 3. Improving responsiveness air brake Simulating signal (Service brake command) (Emergency brake command)

3.1 Higher responsiveness for enhanced braking (Signal simulating Same devices the pressure of air spring) installed in the vehicle performance Brake control unit (Air supply) Piping system Out of braking time, the time having elapsed from a equivalent to the vehicle WSP dump valve A brake command until the specified degree of braking force command starts being applied is defined as idle running time [1]. WSP WSP WSP WSP WSP dump valve The specified degree here is not a uniquely defined concept, dump dump dump dump and idle running time can be determined in various ways, valve valve valve valve device one of which is based on velocity waveform during brak- F1 ing [2]. By reducing idle running time through improved Brake rigging responsiveness, running distance (idle running distance) F2 during idle running time is shortened, with the resultant Volume simulating brake rigging A F1 F2 : Pressure measuring point effect being proportional to the initial braking speed. This paper describes a study in which air brake re- Fig. 2 Configuration of equivalent air piping model sponsiveness was evaluated in a stationary state. For that reason, idle running time was determined based on brake cylinder (BC) pressure [3], a method considered empirically Electro-magnetic valve command almost equal to the velocity waveform-based method men- Pressure tioned above, while a time constant representing the time Time constant -1 Outlet of that is required for BC pressure to reach 63.2 % (= 1-e ) of (×100 kPa) 0.31 s a set point after receiving brake command input was used 8 the relay valve (A) as the parameter for idle running time. 6 4 3.2 Factors impacting responsiveness and methods 2 8 Time constant BC pressure (F1) for improving responsiveness 1.09 s 0 6 8 With the standard air brake system shown in Fig. 1, 4 6 BC pressure (F2) the pilot pressure generation process for the service brake 2 4 is different from that for the emergency brake while these 0 2 brakes share a common circuit downstream of the relay 0 valve. On the latest vehicles, the valves have been reduced 0 1 2 3 4 5 6 in size and housed in mounting seats within a compact, Time (s) one-piece BCU housing, and the volume of valve elements and interconnecting air lines has been reduced. Fig. 3 BC pressure response in equivalent air piping An air piping model, shown in Fig. 2, equivalent to model that of a certain vehicle model was produced. The air pipe lengths and the arrangement of the piping equipment was Upstream side (A) Downstream side based on that of the equivalent vehicle model. Actual parts (Relay valve side) (Total volume of pipe and were used for some of the components, including the BCU, brake cylinder downstream from relay valve) (part of) the foundation brake rigging. On this air piping model, Fig. 3 shows BC pressure response during magnet Pressure: Pressure: valve-controlled braking that corresponds to emergency PH PL braking of 1067 mm gauge line trains. The time constant Volume:VH Volume:VL was 0.31 seconds at the relay valve outlet and 1.09 seconds at the circuit end. With the time constant at the circuit Diameter of orifice: S end more than three times greater than that at the relay valve outlet, it was presumed that the time taken to pres- Fig. 4 Tank pressurization surize the circuit located downstream from the relay valve might account for a great portion of idle running time. where t is time (s) taken for the downstream tank pres-

Then, assume two tanks connected to each other, one sure to become equal to the upstream tank pressure; PH, larger than the other. The larger tank is positioned up- upstream pressure (kPa); VL, downstream tank capacity (l); stream from the smaller tank as shown in Fig. 4. The S, sectional area (mm2) of connection pipe; n, specific heat time taken for the downstream tank pressure to become ratio (1.4 for standard atmosphere); and T, temperature (K). equal to the upstream tank pressure after (A) is opened Upstream tank capacity (VH) was ideally set at ∞. is expressed using (1) quoted from the reference [4]. (The Based on the relationship defined above, shortening numbers in (1) are in SI units whereas the corresponding tank pressure equalization time, or improving responsive- numbers in the original equation are not.) ness, can be achieved by (a) increasing the upstream capac- ity and pressure, (b) increasing the connecting pipe diam-  101.3  V 1 273 t =1.285 −  ⋅5. 23 ⋅ L ⋅ (1) eter or (c) decreasing the downstream capacity. Achieving  PH  S n T option (a) on actual vehicles on which (A) is the relay valve

QR of RTRI, Vol. 58, No. 1, Feb. 2017 29 outlet will require both the capacity of the supply reservoir Out of braking response time, these procedures are and the flow rate of the relay valve to be increased. In- expected to help to reduce the time having elapsed from creasing the connecting pipe diameter (the option (b)) will a brake command up to the time when the air circuit be- necessitate increasing the downstream capacity, which con- tween the relay valve and the WSP dump valves is pres- tradicts (c). surized. Consequently, this paper proposes the method for im- proving responsiveness using option (c) to shorten the time 3.4 Response performance test required to pressurize the circuit downstream from the relay valve, while utilizing WSP dump valves and keeping BC pressure response was measured using the follow- any change to the current vehicle configuration to a mini- ing methods (Fig. 6). mum. (1) Conventional control method that corresponds to emergency braking for 1067 mm gauge line trains, 3.3 Improving air brake responsiveness by using using an equivalent air brake circuit WSP dump valves (2) Responsiveness improving method, using an equiv- alent air brake circuit WSP dump valves are positioned near the and (3) Responsiveness improving method, using an actual consist of a pair of valves - a halt magnet valve (HV) and vehicle a release magnet valve (RV) - per axle. By combining the BC pressure was measured at two points, F1 and F2 operations of these magnet valves, three statuses can be in Fig. 2, both at the brake cylinder inlet. As shown on achieved: supply, exhaust and hold (Table 1). Energizing the horizontal axis in Fig. 6, the start time for the method an HV closes the air line to the BC. Using this character- (1) was at magnet valve open command and that for the istic, the control software is modified to change the brake methods (2) and (3) was at HV de-energization command. command procedures as follows (Fig. 5). There was no involvement of jerk control in these tests. As (1) The HV is energized to close the air line to the BC the control software for an actual vehicle restricts brake before a command is sent to the electro-pneumatic operation in relation to the safety system and other vehicle change valve (or the magnet valve). functions, the measurements using the method (3) were (2) When braking force starts being applied, the HV is de- conducted in test mode whereby the WSP dump valves energized to open the air line to the BC. were energized and de-energized by one axle at a time. At the stage (1), the RV can be in any state. If it is an- Pressure set points for measurement were about 700 kPa ticipated that unintended air pressure may stay in the BC for the equivalent air brake circuit, and about 530 kPa for by any chance, the RV can be simultaneously energized to the actual vehicle due to load compensating control. positively and completely release air pressure from the BC. As shown by the results of measurements using the methods (1) and (2) on the same equivalent air brake cir- Table 1 Response of WSP dump valves to commands cuit, the time constant in the conventional braking was 1.09 seconds whereas that in the braking using the responsive- Release magnet valve (RV) ness improving method was just 0.23 seconds. The time constant in the method (3) using an actual vehicle was also Energized De-energized just 0.26 seconds, which are nearly equal to the time con- stant for the equivalent air brake circuit in measurements Energized Exhaust Hold using method (2). Comparison of the waveforms from methods (2) and (3) Halt magnet valve (HV) reveals that, while both the methods are designed for re- De-energized (Prohibited) Supply (Restore) sponsiveness improvement and have nearly the same time

Conventional Proposed sequence 800 sequence (High response) (A)

1 Brake command Brake 600 (B) control unit Electro-pneumatic valve or Electro-magnctic valve ON Supplying air uo to (3) Proposed sequence (shutoff the inlet of the valve in advance 400 (by Real car, WSP testing mode) Relay valve passage) (2) Proposed sequence to other axles (by Testing set equivalent to Time constant the real car piping system)

Response time WSP (1) 1.09 s dump valve HV Initiating BC pressure (kPa) 200 (1) Conventional sequence 1 (2) 0.23 s device OFF brake (by Testing set equivalent to the (open passage) Exhaust RV real car piping system and (3) 0.26 s applying emergency brake)

Response time 0 Applying 0 1 2 3 4 2 2 brake Time (s) Fig. 5 Improving air brake responsiveness by using WSP Fig. 6 BC pressure response with responsiveness im- dump valves proving methods

30 QR of RTRI, Vol. 58, No. 1, Feb. 2017 constant, the transient response portions ((A) in Fig. 6) of entiate instantaneous power supply interruption due to the the waveforms are different from each other. This appears train passing a feed section or for other reasons [5]. The to have been caused by the upstream flow having become idle running time is then the sum of the delay and the time full in the method (2) as the WSP dump valves on all four constant specific to the brake system. The proposed meth- axles are energized at the same time whereas in the meth- od of energizing and de-energizing the HV combined with a od (3), these valves are energized and de-energized one time delay feature similar to the Shinkansen’s offers a pos- axle at a time. In Fig. 6, BC pressure dips a little in the sibility to improve responsiveness of air brake (Fig. 7). portion (B) when the WSP dump valves on the adjoining Simply improving responsiveness can generate shock axle are operated in test mode. This also appears to have loads from braking, negatively impacting ride quality and been caused by restriction in the upstream flow rate. couplers and other equipment. Therefore, the method must be modified so as to eliminate such faults before be- 3.5 Other applications of the responsiveness im- ing put to practical use. proving method

The proposed method for improving responsiveness 4. Reducing air consumption for air braking uses the WSP dump valve that can be electrically con- trolled, and is positioned closest to the BC in order to Brake cylinders may need to be made larger (volume shorten the time required for the compressed air to pres- increase) in the future to increase air braking force. How- surize the circuit. The method is realized through modifi- ever, the increased braking force may generate more wheel cation of the control software. As for the method, the WSP slides, resulting in higher frequency of WSP operation. dump valve is commanded to open or close the air line. Air These scenarios will likely lead to increased air consump- pressure level still needs to be regulated through the con- tion. trol valves set in the BCU. This requires the braking force With that in mind, air consumption comparison be- (notch) to be applied (selected) to be known before the pro- tween the slip rate WSP control method [6], which is one of posed method is used. the WSP control methods used in actual train operations, In actual vehicles, there are instances where brake ap- and the TL-type WSP control [7], which is an improved- plication is delayed until a judgment is made. On Shink- deceleration version of the slip rate WSP, was made us- ansen, for example, the power supply to overhead contact ing a hybrid simulator consisting of an actual vehicle and lines is suspended when there is an earthquake and trains simulation. apply the emergency brake and stop when they detect the power outage [5]. In that case, a delay is introduced be- 4.1 WSP control methods with less air consumption tween the voltage drop and the brake application to differ- 4.1.1 Relationship between adhesion and braking outage force

Supplying The purpose of braking is to decelerate and stop trans- power Power outage detection lational motion of the vehicle. With the adhesive brake, and brake command Power outage which utilizes adhesion between wheels and rails, when detection flag braking force is simply increased or decreased while the Brake command train is slipping as shown in Fig. 8, effective braking force against translational motion stays within the adhe- BC pressure sion limit for the period X during which braking force is

ta greater than the adhesion limit, allowing the train to slip Conventional Time Power outage detection tb sequence delay Command decision further. As the WSP control reduces braking force to the tx Time constant of brake system Adhesion limit Total response time Braking force (Unmeasurable in practice)

Additional sequence Electro-pneumatic valve (or electro-magnetic valve) command HV command Proposed sequence (X) (Y) (High response) BC pressure Retarding force ta (Effective braking force) Time Power outage detection Reduced tb time delay Command decision Braking force>Adhesion limit Braking force

QR of RTRI, Vol. 58, No. 1, Feb. 2017 31 Assumed braking force Adhesion limit applied by complicated WSP (Unmeasurable in practice) Action of the Slide Stay Re-adhesion in proportion to adhesion force WSP dump valve

Supply Exhaust Hold Supply

Vehicle speed

Axle speed Assumed braking force applied by simple WSP

:Colored area shows saved unnecessary air supply Threshold for or exhaust detection by ΔV

Time BC pressure Fig. 9 Relationship between adhesion limit and braking force (2) (Ideal WSP control) extent that it is less than the adhesion limit, as in period Y, the braking force contributes to weakening translational motion, making the train slip less. Presuming that ideal BC pressure will be completely exhausted if “phased exhaust” is brake control under such changing relationship between repeated 5 times. adhesion limit and braking force is to decelerate the train without causing it to slip while taking full advantage of Fig. 10 Outline of slip rate WSP control wheel-rail adhesion, this can be expressed as continuously applying braking force that is equal to adhesion limit as 4.1.3 TL-type WSP control method shown in Fig. 9. Furthermore, release is minimized by curtailing slide TL-type WSP control [7] (Fig. 11, hereafter TL-WSP) detection. Therefore, air consumption for WSP control is which is based on SR-WSP, is the one to be featured as fol- minimized by the following procedures: lows:

・ Controlling BC pressure to follow the adhesion limit (i) Uses estimated time up to wheel lock (TL) (s) defined curve as closely as possible by (4) in place of β detection for slide detection. ・ Making slip less detectable while maintaining anti-wheel lock performance TL = Axle speed(km/h)/Axle deceleration (km/h/s) (4) 4.1.2 Slip rate WSP control method (ii) Breaks up BC pressure release stages, and also sets Figure 10 outlines slip rate wheel slide control [6] a temporary-restoration point before re-adhesion and (hereafter SR-WSP), in which slip is handled in three uses it as the phased supply start point. states based on preset thresholds, namely“ slide”,“ stay” (iii) Limits re-slips by applying pressure in stages during a and“ re-adhesion (restoration),” while BC pressure is ap- restoration process from a slip. plied or released by the WSP dump valve operating accord- ing to state-specific rules. Slip is detected based on the Temporary logical sum of speed difference / slip rate detection (hereaf- restore Action of the Slide Stay Re-adhesion ter“ detection”) and deceleration detection (hereafter“ WSP dump valve Stay ΔV β Supply detection”). Speed difference ΔV (km/h) and slip rate η (%) (in case of “Re-adhesion”) Supply Exhaust Hold are defined by (2) and (3) respectively.

Vehicle speed ΔV = Reference speed - Axle speed (2) Axle speed

Threshold for η = ΔV /Reference speed・100 (3) detection by ΔV

Reference speed indicates vehicle speed essentially. Ei- BC pressure ther non-slipping axle speed or speed corrected for control (In the case of re-adhesion) application are practically substituted. In SR-WSP, a slip is processed as a complete cycle starting with generation, (In the case of SR-WSP) followed by attenuation and ending with re-adhesion, with the ultimate purpose of achieving re-adhesion without fail. BC pressure will be completely exhausted if “phased exhaust” is repeated 10 times. Fig. 11 Outline of TL-type WSP control

32 QR of RTRI, Vol. 58, No. 1, Feb. 2017 Estimated time up to wheel lock, proposed in (i) above, 4.2.2 Simulation conditions is the parameter designed to secure enough time for BC pressure to be released completely before the wheel is The simulation was conducted on a one-car Shinkan- locked. The control features (ii) and (iii) above are in- sen train set using a BC pressure profile relative to train tended to prioritize hold and supply over exhaust in slips speed (Fig. 13). The R291, which was also involved in the to maintain high BC pressure, which appears to be an ef- simulation, was a 1067 mm gauge line unit which is dif- fective strategy to prevent unnecessary exhaust and help ferent to the Shinkansen but shares some specifications reduce air consumption. including foundation brake rigging and air tubing length. Adhesion limits, which could not be measured physi- 4.2 Air consumption measurement using an actual cally, were estimated by extrapolation of a function of the vehicle adhesion coefficient (Fig. 14). Adhesion limits were inter- polated for other speeds as well while various adhesion co- 4.2.1 Hybrid simulation efficients were set up through a combination of sine waves and random numbers. In hybrid simulation (Fig. 12) involving the RTRI type Table 2 shows the parameters used in the simulation of 291 test vehicle (hereafter“ R291”), the volume of air con- SR-WSP (hereafter“ conventional control”) and TL-WSP sumed for WSP control was measured in a setup that con- (hereafter“ proposed control”.) sidered a range of factors including foundation brake rig- ging and air piping length. With the R291, the auxiliary BC 600 pressure generator can produce any BC pressure required 560 460 for WSP control simulation. The R291 is equipped with air tubing, WSP dump valves and foundation brake rigging, all 400 equivalent to actual vehicles, except that it has compressed 260 air supplied from the main reservoir and double check 200 valves positioned downstream from a relay valve. The sim-

ulation was conducted with no power applied on the vehicle BC pressure (kPa) while electric power and compressed air for measurement 0 70 118 320 and control devices were provided from external sources. 0 50 100 150 200 250 300 350 Two simulators were used for the simulation. One is Speed (km/h) a vehicle dynamics simulator that computes each circum- ferential speed of axle and vehicle (translational motion) Fig. 13 BC pressure profile applied to the BCU simulator speed based on the actually measured BC pressure input, with the preset data containing specifications for founda- 0.20 tion brake rigging including its cylinder diameter, brake 0.185 block friction coefficient and vehicle weight. The other is a ≦ 0.15 30 km/h BCU simulator that executes WSP control based on simu- lated axle speed computed by the vehicle dynamics simula- 0.10 0.065 tor at BC pressure generating command signal output. Micro slip area Considering the capacity of the flow meter being used and the need to keep the air supply circuit from being re- 0.05 300 km/h 0.006 0.018 stricted during braking, the flow rate of air exhausted from Adhesion coefficient the WSP dump valves was measured as an indication of air 0.00 consumption. 0 8 20 40 60 80 100 Slip rate (%) Simulated axle speed Brake command Fig. 14 Adhesion coefficient characteristics applied to BCU Vehicle dynamics vehicle dynamics simulator simulator simulator BC pressure WSP Table 2 WSP control parameters dump valve generating command command Simulator Type of WSP controller Conventional Proposed Supplied from Auxiliary BC Actual device an outer system pressure generator (Max. 700 kPa) ΔV detection β > 3 AND η > 5,10,15,20 BC pressure Air compressor Electro-pneumatic valve β detection β > 30 - Main reservoir Relay valve Volume:330L TL detection - TL=3.0 WSP WSP Pressure transducer (Check valve) WSPdump dump WSPdumpvalve The number of phased exhaust steps 5 steps 10 steps Double dumpvalve valve （Exhaust） Usual air flow line check valve （Exhaust） Air flow meter (not in use in this test) valve (Exhaust) （ExhausAir flowt） meter temporary Air flow meter Phased supply - Air flow meter restoration Sub-system per an axle η: Slip rate (%), β: Deceleration (km/h/s), TL: Estimated time up to Fig. 12 Hybrid simulation wheel lock (s,) common parameter :“ Stay” β < 2“，Re-adhesion” ΔV < 3.

QR of RTRI, Vol. 58, No. 1, Feb. 2017 33 4.2.3 Test results 100 96 Hybrid simulation results are shown in Fig. 15 and (SR-WSP) 80 Fig. 16. Figure 15 is an example of time-series charts 17 Detected by ΔV Detected by β while Fig. 16 indicates air consumption and mean decel- (TL-WSP) eration. 60 In both the conventional and proposed controls, there Detected by ΔV was a trend that higher slip rates under the slide detection 69 21 condition (hereafter detection slip rates) resulted in less air 40 consumption. Figure 17 indicates that higher slip rates re- 40 31 sulted in a lower number of slide detections, which implies 20 33 37 that fewer detections correspond to lower air consumption. (total amount of 4 axles) 30 20 For the detection slip rate of 10 % or more, the proposed 9 9 control achieved less air consumption than the convention- The number of slide detected times 0 al control. There were many β detections in the conven- 5 10 15 20 tional control while in the proposed control, for which only Threshold for a slide detection slip rate (%) ΔV detections are shown, there was no wheel lock. Fig. 17 Detection slip rates and number of detected slides These results were reversed at the detection slip rate of 5 %. This appears related to the relatively high adhe- 5. Conclusion sion limit in the micro slip area (corresponding to the area with a slip rate of 8 % or less in Fig. 14) facilitating re-ad- This paper proposes a method for reducing air brake hesion even with the conventional control, which releases response time using WSP dump valves and another for and holds BC pressure longer than the proposed control, reducing air consumption in WSP control, in order to im- helping to reduce air consumption by the amount due to prove air brake performance by taking full advantage of non-phased supply. the existing vehicle facilities and improving related soft- ware. For both methods, vehicles were retrofitted with Speed WSP dump valves with control software modification. (×10 km/h) Brake command 30 Simulated axle speed Initial speed of the braking 320 km/h Simply improving responsiveness may generate shock 30 1st axle Mean deceleration 1.87 km/h/s loads from braking, negatively impacting ride quality inter 25 30 based on the braking distance 25 30 alia. Further research will be conducted going forward to 2nd axle 20 25 enable the proposals to be put to practical use while taking 20 25 15 20 a closer look at possible effects, both positive and negative. 15 20 3rd axle Part of the simulation was made possible through utili- 10 15 Pressure 1st axle (×100 kPa) zation of the results of joint research conducted by Odakyu 10 15 BC pressure 4th axle 6 5 10 (measured in actual devices) 2nd axle 6 4 Electric Railway Co., Ltd., Mitsubishi Electric Corporation, 5 10 3rd axle 6 4 2 University of Tsukuba and RTRI. 0 5 6 4 2 0 0 5 4 2 0 0 4th axle 2 0 0 0 0 20 40 60 80 100 120 140 160 Acknowledgements Time (s) Fig. 15 Hybrid simulation charts (TL-WSP with detection The authors would like to express their sincere grati- slip rate of 10%) tude to JR Kyushu Railway Company and Nabtesco Cor- poration for providing extensive support in conducting 2.0 response characteristics test involving actual vehicles and Mean deceleration

based on the braking distance (km/h/s) Mean deceleration equivalent air brake circuits.

SR-WSP TL-WSP 1.90 1.89 1.9 1.88 1.86 1.87 1.86 References 1,000 1.85 1.85 SR-WSP 800 862 1.8 [1] JIS E4001 - Railway rolling stock - Vocabulary. 724 680 TL-WSP [2] JIS E6004 - Electric rolling stock - General rules for 605 Air consumption 600 performance tests. 483 509 421 [3] Japan Train Operation Association, Theory for Efficient 400 335 Train Operation (2nd revision), 2010 (in Japanese). 200 [4] Koji NAKANISHI, Learning from the Basics: Air Pres- Air consumption (L(ANR)) (amount of integrated air flow four axles) sure Technology, Ohmsha, 2001 (in Japanese). 0 [5] Shinichiro TAJIMA,“ A seismic Activities by East Ja- 5 10 15 20 pan Railway Company - Focusing on Vehicles,” Rolling Threshold for a slide detection slip rate (%) Stock Industries, Vol.462, pp.37-39, 2012 (in Japanese). Fig. 16 Air consumption and average deceleration [6] Norimichi KUMAGAI, Izumi HASEGAWA, Seigo against detection slip rates UCHIDA, Kazunori WATANABE,“ The Slip rate Wheel Slide Control System Using Synchronized Speed Pulse

34 QR of RTRI, Vol. 58, No. 1, Feb. 2017 Computation for Shinkansen Brake,” Transactions of Slide Protection System using a New Detection Al- the Japan Society of Mechanical Engineers, Series C, gorithm,” Quarterly Report of RTRI, Vol. 52, No. 3, Vol. 70, No. 689, pp.135-141, 2004 (in Japanese). pp.136-140, 2011. [7] Shin-ichi NAKAZAWA,“ Development of a New Wheel

Authors

Shin-ichi NAKAZAWA Daisuke HIJIKATA Senior Researcher, Brake Control Laboratory, Researcher, Brake Control Laboratory, Vehicle Vehicle Control Technology Division Control Technology Division Research Areas: Brake System Design, Wheel Research Areas: Braking performance Slide Protection System Design evaluation, Wheel Slide Protection

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