Method for operating a friction wheel press system of a hydraulically driven monorail aerial ropeway

Abstract

The invention relates to a method for operating a friction wheel press system of a hydraulically driven monorail aerial ropeway (1), which comprises a plurality of power units, each having a friction wheel drive and a press device for the friction wheel, the friction wheel (7) being pressed onto the track with a variable pressing force by means of a pressing cylinder and being driven by a hydraulic motor by means of a working pressure, the pressure differential of the working pressure of the hydraulic motor in a closed hydraulic circuit being dependent on load, inclination and speed, the pressure differential of the working pressure being measured at one single measuring point by means of a measuring value sensor, the pressing force of the pressing cylinder being determined by means of a mathematical function stored in a control unit from the pressure differential of the working pressure, the pressing force being adjusted by means of an electronic proportional pressure control valve, all pressing cylinders being connected to a common pressure supply line, in which the pressing force is adjusted for all pressing cylinders by means of the electronic proportional pressure control valve.

Description

Technical Field

[0001] This invention relates to a method for a friction wheel clamping system for operating a hydraulically driven monorail aerial cableway. Background Technology

[0002] In a friction wheel system, a hydraulic cylinder presses the friction wheel against the track with a normally constant compressive force designed for maximum tensile load. Therefore, a high compressive force is applied even at low traction. The load and wear on the friction wheel are higher than necessary. On the other hand, it should be noted that slippage frequently occurs in track areas with low static friction coefficients. Therefore, the compressive force cannot be too low either.

[0003] DE-197 18 515 A1 discloses a method for reducing friction wheel wear and an arrangement system for implementing this method. An electric motor connected to the friction wheel is located in the drive unit. A speed sensor is integrated into the chassis of the drive unit. Furthermore, a tilt monitor is provided in the control module, which can be connected to the frequency converter module, power module, and motor module via flanges. To reduce friction wheel wear, the speed of the transport mechanism is continuously measured, and the pressure of the friction wheel on the running track is steplessly adjusted according to a programmable curve that predetermines the allowable pressure of the speed. To determine the required pressure, three variables of the entire train—speed, tilt, and downhill force—are continuously determined. The required pressure is derived from a curve stored in the system based on this continuously measured triplet of data. For this purpose, a speed sensor and a tilt monitor are provided in the area of ​​the drive unit, and a strain gauge is provided on a connecting rod between the drive unit and the first lifting beam. However, the three measuring sensors are positioned in only one location, between the drive unit and the load generated by the multiple carriages suspended above it. This introduces the risk that measurements of inclination values, and particularly downhill values, within the drive unit area at a single saddle location on the EHB (where at least a portion of the drive unit and the suspended load train are located on different sides of the saddle or slot) do not reflect the actual load distribution of the EHB. This could lead to the determination of incorrect and, in the worst case, insufficient compressive stress, potentially causing accidents. This risk can only be eliminated by painstakingly and costly installing additional measuring sensors at multiple locations throughout the EHB and synchronizing them. While the method can be adapted in some cases to EHBs suitable for explosion-proof areas, this incurs further costs due to the explosion-proof design of the numerous electronic components required for this method. Summary of the Invention

[0004] The purpose of this invention is to provide a method for operating a friction wheel clamping system that generates a compressive force that protects or does not damage the friction wheel, thereby improving the efficiency of the friction wheel and extending its service life.

[0005] This objective is achieved by a method according to the invention for a friction wheel clamping system for operating a hydraulically driven monorail cableway, the monorail cableway comprising multiple power units, each power unit having a friction wheel drive device and a clamping device for the friction wheels. The friction wheels are pressed onto the track by a clamping cylinder with variable clamping force and are driven by a hydraulic motor by a working pressure. The pressure difference of the working pressure of the hydraulic motor within a closed hydraulic circuit is related to the load, inclination, and speed. The pressure difference of the working pressure is measured using a measuring value sensor at a single measuring point. A mathematical function stored in a control unit determines the clamping pressure of the clamping cylinder based on the pressure difference of the working pressure. The clamping pressure is adjusted by an electronic proportional pressure control valve. All clamping cylinders are connected to a common pressure supply line, in which the clamping pressure of all clamping cylinders is adjusted by the electronic proportional pressure control valve.

[0006] The method of the friction wheel clamping system for operating a hydraulically driven EHB according to the present invention specifies pure hydraulic drive and is therefore also suitable for explosion-proof areas. The monorail or trainset used in this method provides multiple power units, which, due to the hydraulic energy supply, can be arranged at a distance from the pressure source, i.e., at a distance from the motor-pump-assembly. Each of the multiple power units has a friction wheel drive device and a clamping device for the friction wheel. The friction wheel is pressed onto a travel track by a compression cylinder with variable compression force and is driven by a hydraulically driven motor under working pressure. The torque of the hydraulic motor is proportional to the displacement of the hydraulic motor, the hydraulic mechanical efficiency, and the pressure difference of the working pressure. On the other hand, the torque is inversely proportional to the radius of the friction wheel. Furthermore, the traction force (friction force) that can be transmitted by the friction wheel is proportional to the product of the friction coefficient (friction wheel-track) and the compression force on the friction wheel. Because the compression of the friction wheel is achieved hydraulically by the compression cylinder, the compression force is also proportional to the efficiency of the hydraulic cylinder, the effective piston ring area of ​​the compression cylinder, and the compression pressure.

[0007] In this invention, the differential pressure of the drive motor's operating pressure within a closed hydraulic circuit is detected. This differential pressure is related to the load, inclination, and speed of the monorail aerial cableway. This differential pressure is used as an input parameter for a mathematical function stored in the control unit to determine the clamping pressure of the clamping device. The clamping pressure is proportional to the differential pressure of the operating pressure.

[0008] The differential pressure of the extrusion pressure is converted into voltage by a transducer, and this voltage is supplied as a control parameter to an electronic proportional pressure control valve that regulates the extrusion pressure. According to the invention, all extrusion cylinders are connected to a common pressure supply line. The electronic proportional pressure control valve regulates the extrusion pressure of all extrusion cylinders used for the EHB. The required extrusion pressure for each of the friction wheels depends only on the working pressure, apart from the material constant of the friction wheel material. This closed loop ensures that each drive motor is uniformly loaded with drive pressure, and that the working pressure or differential pressure automatically generated by the load is the same at every position throughout the hydraulic system, even in the saddle position of the EHB.

[0009] Because of the closed hydrostatic circuit, the working pressure can be advantageously measured at any point within the circuit. Therefore, compared to existing technologies, this saves the cost of potentially making numerous electronic components measuring different parameters explosion-proof. This invention is low-cost due to the use of an inexpensive electronic proportional pressure control valve, where only a single measuring point is needed throughout the system to regulate the compression pressure for all drive units. Therefore, the pressure difference is measured at only one single measuring point using a single sensor. This is possible because all power units are connected in parallel within a closed hydrostatic circuit. Only one single pressure sensor is needed, which can be placed at any point in the hydrodynamic circuit, i.e., any point on the train. The compression pressure can be continuously calculated from the continuously measured pressure values.

[0010] In an advantageous development of the invention, pressure reduction is achieved with a time delay. This avoids the effect that, when slippage might occur on the friction wheel and therefore the extrusion pressure decreases as the pressure differential drops, this would amplify rather than reduce slippage. The time delay after a definitively set time provides the system with the possibility of traversing a segment with a lower coefficient of friction at the cost of some slippage, or ensures that a defined minimum extrusion pressure is maintained while keeping the extrusion pressure constant.

[0011] By continuously adjusting the extrusion pressure, optimal load-related and protective extrusion pressure for the friction wheels can be generated at any time. This results in improved friction wheel efficiency and extended service life, avoiding unnecessary overload of the friction wheels. The extrusion pressure can be optimally adapted to the friction coefficient of the track-friction wheel connection according to the environmental conditions in the mine. For this purpose, the extrusion pressure determined by the control unit can be manually corrected by the operator of the monorail aerial ropeway. The friction coefficient adapted to local conditions, as well as other parameters of the hydraulic mechanical system affecting the working pressure or extrusion pressure, can also be stored in the control unit. The modular monorail aerial ropeway has a motor-pump-assembly, where the motor is preferably an internal combustion engine, particularly a diesel engine. Within the trainset, the power unit is arranged in any location, particularly away from the motor-pump-assembly. The pump of the motor-pump-assembly provides hydraulic fluid to all power units at the corresponding working pressure or extrusion pressure. Attached Figure Description

[0012] The invention is now described with reference to embodiments shown in the accompanying drawings. The drawings show:

[0013] Figure 1 It is a purely schematic side view of a monorail aerial cableway;

[0014] Figure 2 This is the working principle of the friction wheel drive device, and

[0015] Figure 3 This is a functional overview diagram of the layout system used to implement the method of the present invention. Detailed Implementation

[0016] Figure 1 A monorail aerial cableway 1 is shown, comprising a driver's cab 2 at both the front and rear ends, and a motor-pump assembly 3 for providing hydraulic pressure to drive multiple power units 4 distributed along the length of the train or EHB1. Additionally, a lifting beam 5 is provided for support. The individual modules of the train are interconnected via connecting rods.

[0017] As in Figure 2 and 3 As schematically shown, the monorail aerial cableway 1 shown is driven by a friction wheel drive device in a purely hydraulic manner. Figure 2 A track 6 is shown, which is arranged between friction wheels 7, which are pressed onto the track 6 by a compression cylinder 8 with a compression force F_An.

[0018] Figure 3As shown, a compressive pressure p_An is applied for compression, and the compressive cylinder applies this compressive force F_An to the friction wheel 7 via this compressive pressure. Each friction wheel 7 is driven by a hydraulic motor 9. This hydraulic motor applies a torque M to the corresponding friction wheel 7. A traction force F_Z is transmitted to the track 6 via a radius r connected to the compressive force F_An, causing the train or monorail cableway 1 to move along the track 6.

[0019] The hydraulic motor 9 is supplied with hydraulic fluid by pump 10 of the motor-pump assembly 3, which is supplied at a working pressure p_A. The hydraulic motor 9 performs work, wherein the hydraulic fluid flows back to pump 10 in a closed hydraulic circuit at pressure p_B. The pressure difference Delta p_A is determined by a measuring value sensor 11 and converted into an electrical signal by a measuring value converter 12.

[0020] A mathematical function is stored in control unit 13 that determines the extrusion pressure p_An based on the pressure difference Delta p_A between the input voltage or the working pressure p_A. For this purpose, an electrical signal is transmitted to an electronic proportional pressure control valve 14 connected to the pressure supply unit 15. The pressure supply unit 15 is implemented via the motor-pump assembly 3. Even if the input pressure is variable, the electronic proportional pressure control valve 14 maintains a constant output pressure. The pressure change of the extrusion pressure p_An is proportional to the control signal from control unit 13. The conversion of the extrusion value determined in control unit 13 is not achieved through a proportional valve, but through the aforementioned electronic proportional pressure control valve. This loads the hydraulic pressure supply line of the extrusion cylinder 8 of the power unit 4 of the friction wheel drive device, all of which are connected in parallel via hydraulic lines. The continuous extrusion pressure p_An is calculated, particularly considering the material-related coefficient of friction of the friction wheel-rail connection. The continuous extrusion pressure calculation is based on continuous, i.e., constant pressure measurement, to generate the optimal load-related extrusion force that protects or does not damage the friction wheel at all times.

[0021] The following are the mathematical formulas used to calculate the extrusion pressure p_An, the extrusion force F_An, the hydraulic motor torque M, and the extrusion pressure P_An related to the working pressure Delta_p_A. They are:

[0022] The compressive pressure p_An[Pa] of the friction wheel

[0023] The compressive force F_An[N] on the friction wheel

[0024] The transmittable traction force (friction force) on the friction wheel is F_Z[N].

[0025] Torque M [Nm] on the friction wheel

[0026] The rotational speed n [l / s] of the hydraulic motor

[0027] Friction wheel radius r [m]

[0028] The effective piston ring area of ​​the extrusion cylinder is A_Zyl[m 2 ]

[0029] The power P [W] of a hydraulic motor

[0030] The displacement V_M[m] of the hydraulic motor 3 ]

[0031] The pressure difference Delta_p_A [Pa] at the working pressure.

[0032] The hydraulic mechanical efficiency ny_mh = 0.9

[0033] The efficiency of the hydraulic cylinder is ny_Zyl = 0.9

[0034] coefficient of friction my

[0035] Extrusion pressure p_An: F_An = p_An * A_Zyl * ny_Zyl

[0036] p_An = F_An / (A_Zyl * ny_Zyl)

[0037] Extrusion pressure F_An: F_Z = my * F_An = M / r

[0038] F_An = M / (r * my)

[0039] The torque of a hydraulic motor is P = 2 * pi * n * M = V_M * delta_p_A * n * ny_mh

[0040] M=(V_M*delta_p_A*ny_hm) / (2*pi)

[0041] Extrusion pressure related to working pressure

[0042] p_An=(M / (r*my) / (A_Zyl*ny_Zyl)

[0043] =(((V_M*delta-_p_A*ny_hm) / (2*pi)) / (r*my)) / (A_Zyl*ny_Ayl)

[0044] =((V_M*ny_hm) / (2*pi*r*my*A_Zyl*ny_Zyl))*delta_p_A

[0045] List of reference numerals

[0046] 1. EHB (Extended Helicopter)

[0047] 2 driver's cab

[0048] 3 Motor-Pump-Assembly

[0049] 4 Power Unit

[0050] 5 Lifting Beams

[0051] 6 orbitals

[0052] 7 friction wheels

[0053] 8 extrusion cylinders

[0054] 9 hydraulic motors

[0055] 10 pumps

[0056] 11 Measurement value sensor

[0057] 12 Measurement Value Converter

[0058] 13 control units

[0059] 14 Electronic proportional pressure control valve

[0060] 15 pressure sources

[0061] Delta_p_A pressure difference

[0062] F_An Extrusive force on the friction wheel

[0063] F_Z traction force

[0064] M driving torque

[0065] p_An Extrusion pressure

[0066] p_A Work pressure

[0067] back pressure of p_B p_A

[0068] The radius of r 7

[0069] u control signal

Claims

1. A method for a friction wheel clamping system for operating a hydraulically driven monorail aerial ropeway (1), a) The monorail aerial cableway includes multiple power units (4). b) The power unit has a friction wheel drive device and a clamping device for the friction wheel (7), c) The friction wheel (7) is pressed onto the track (6) by a pressure cylinder (8) with a variable pressure (F_An) and is driven by a hydraulic motor (9) by a working pressure (p_A). d) The pressure difference (Delta_p_A) of the working pressure (p_A) of the hydraulic motor (9) within the closed hydraulic circuit is related to the load, tilt, and speed. e) Measure the pressure difference (Delta_p_A) of the working pressure (p_A) at a single measurement point using a measurement value sensor (11). f) The mathematical function stored in the control unit (13) determines the extrusion pressure (p_An) of the extrusion cylinder (8) based on the pressure difference (Delta_p_A) of the working pressure (p_A). g) Adjust the extrusion pressure (p_An) by means of electronic proportional pressure control valve (14). h) All extrusion cylinders (8) are connected to a common pressure supply line in which the extrusion pressure (p_An) of all extrusion cylinders (8) is regulated by the electronic proportional pressure control valve (14).

2. The method according to claim 1, characterized in that: The pressure reduction of the extrusion pressure (p_An) is achieved with a time delay.

3. The method according to claim 1 or 2, characterized in that: The compression pressure (p_An) determined by the control unit (13) can be manually corrected by the driver of the monorail cableway (1).

4. The method according to claim 1 or 2, characterized in that: The modular monorail cableway (1) has a motor-pump-assembly (3) and a power unit (4) at any position within the train set, all of which are supplied with hydraulic fluid by the pump (10) of the motor-pump-assembly (3).

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