Lateral pressure measuring device and lateral pressure measuring method

Abstract

To provide a lateral pressure measurement device and the like with improved accuracy of lateral pressure measurement.SOLUTION: A lateral pressure measurement device measures a lateral pressure Q between a wheel 100 of a railway vehicle and a rail. The wheel includes a rim part 110 provided on an outer peripheral part and formed with a tread, a boss part 120 provided in a center part and mounted with an axle, and a plate part 130 provided between the rim part and the boss part. The lateral pressure measurement device includes: a plurality of strain gauges, which passes through the plate part in a rotation center axis direction of the wheel and is attached to an inner surface of a hole whose angle position around the rotation center axis is arranged in a range within π / 4 rad so as to detect shear strain of the plate part due to the lateral pressure; and a lateral pressure calculation unit for calculating the lateral pressure based on the output of a bridge circuit constituted of the strain gauges.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a lateral force measuring device and a lateral force measuring method for measuring a lateral force, which is a contact force acting in a lateral direction between a wheel of a railway vehicle and a rail. [Background technology]

[0002] Methods for measuring wheel load and lateral force, which are the contact forces acting between the wheels of a railway vehicle and the rails (so-called PQ measurements), can be broadly divided into methods that measure on the ground using sensors installed on the track side, and methods that measure on board the vehicle using sensors mounted on the vehicle. When measuring wheel load and lateral force for the purpose of evaluating driving safety, a method of measurement on board the vehicle is mainly used.

[0003] One method known for measuring wheel load and lateral force on a vehicle is to measure the deformation of the wheels using strain gauges. In recent years, it has also been proposed to constantly monitor wheel load and lateral pressure by incorporating load cells and displacement sensors into the cart instead of attaching strain gauges to the wheels, as in the so-called PQ monitoring cart.

[0004] As an example of a conventional technique for measuring lateral forces on railway vehicles, Non-Patent Document 1 describes a method in which a plurality of holes (openings) are formed circumferentially in the wheel plate portion, which is located between the rim portion on the outer periphery of the wheel where the tread is provided, and the boss portion through which the axle is inserted, and strain gauges affixed inside the holes are used to detect the amount of bending deformation of the wheel plate portion and measure the lateral forces. Non-patent document 2 describes a device that detects the amount of bending deformation of the wheel plate portion by attaching multiple strain gauges distributed around the wheel plate portion in the circumferential direction, thereby enabling continuous measurement of lateral pressure. Non-Patent Document 3 describes a PQ monitoring cart that detects the amount of bending deformation of the wheel plate based on the lateral displacement of the rim and calculates the lateral pressure. Non-patent document 4 describes a method for measuring lateral force in response to the shear strain of the rim on which the tread is provided for a wheel equipped with a centrally fastened brake disc, where it is difficult to measure lateral force based on the bending strain of the wheel disc portion. Furthermore, Non-Patent Document 5 describes the determination of the average wheel load per one rotation using a strain signal obtained from a bridge circuit for measuring the wheel load of a PQ axle. Also, Non-Patent Document 6 describes the calculation of the average value of the lateral contact position over one wheel revolution for a PQ wheel set using a bending / shear lateral pressure measurement method in combination.

[0005] Furthermore, Patent Document 1 describes that in order to improve the accuracy of measuring lateral force, by calculating the lateral force based on the shear strain of the plate portion of the wheel, it is possible to reduce errors due to moment load caused by wheel load compared to conventional techniques that calculate lateral force based on, for example, bending deformation of the plate portion. Furthermore, Patent Document 2 describes a contact position measuring device that measures the contact position of a railway vehicle wheel with a rail in the sleeper direction, which includes a plurality of contact position measuring strain gauges that are distributed around the wheel circumferentially to detect elastic deformation of the wheel and that form a contact position measuring bridge circuit in which the frequency characteristics of the output waveform during wheel rotation change depending on the contact position, and a contact position calculation unit that calculates the contact position based on the frequency characteristics of the output waveform of the contact position measuring bridge circuit during wheel rotation. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2022-41347 A [Patent Document 2] JP 2022-41349 A [Non-patent literature]

[0007] [Non-Patent Document 1] Hiroaki Ishida, Masaki Matsuo, Kazuhiko Tezuka, Kenji Ueki, "New Method for Measuring Wheel Load, Lateral Force, and Derailment Coefficient of Railway Vehicles (Development of Measuring Device)", Transactions of the Japan Society of Mechanical Engineers, Series C, Vol. 63, No. 614 (1997), pp. 3417-3423. [Non-Patent Document 2] Kiyoshi Sato, Tatsuo Kuboki, Hideki Kanbe, "Development of a wheel load and lateral force measurement system for intermittent and continuous operation", Railway Technical Research Institute Report, Vol. 22, No. 2 (2008), pp. 47-52. [Non-Patent Document 3] Hiroyuki Ohno, Akira Matsumoto, Yasuhiro Sato, Tadashi Shimizu, Masao Tomeoka, Kosuke Matsumoto, Masahisa Tanimoto, and Yoshi Sato, "Measuring method of wheel / rail contact force without using PQ wheelset," Transactions of the Japan Society of Mechanical Engineers, Series C, Vol. 77, No. 774 (2011), pp. 147-155. [Non-Patent Document 4] Hiroaki Ishida and Kenya Endo, "Lateral Force Measurement Method for Wheels with Centrally Fastened Brake Discs," Meisei University Faculty of Science and Engineering Research Bulletin, No. 53 (2017), pp. 39-46. [Non-Patent Document 5] Takatoshi Hondo, "A method for extracting the moving average value of vertical creep force over one rotation of a wheel without requiring a rotation angle sensor for the strain output of a PQ wheelset," Transactions of the Japan Society of Mechanical Engineers, Vol. 87, No. 894, 2021 [Non-Patent Document 6] Takatoshi Hondo, Shoya Kuniyuki, Hisayo Doi, "Contact position information extraction processing method for PQ wheelsets using bending and shear lateral pressure measurement methods," Proceedings of TRANSLOG2021 Summary of the Invention [Problem to be solved by the invention]

[0008] As described in Non-Patent Documents 1 to 3, when measuring the lateral force based on the bending deformation of the wheel plate, if the contact position between the wheel and the rail moves from the center of the tread toward the sleeper, the cross sensitivity of the lateral force measuring means to the wheel load increases, and there is a concern that the measurement error caused by the wheel load will increase. For example, if the contact point between the wheel and the rail moves from the center of the tread to the flange side, a moment load due to the wheel load is applied to the wheel, causing a larger bending deformation than when only lateral force is applied, and the lateral force may be mistakenly recognized as being greater than it actually is. In such a case, for example, in a running safety evaluation, the vehicle may be judged to be dangerous even though it is actually safe. Furthermore, as described in Non-Patent Document 4, when trying to measure lateral pressure based on the shear strain of the wheel rim, it has become clear that the measurement point where the strain gauge is installed is close to the contact point between the wheel and the rail, and is therefore strongly affected by the wheel load. Furthermore, as described in Patent Document 1, when lateral force is measured using the shear strain of the plate portion of the wheel, the influence of wheel load can be suppressed more than when lateral force is measured using bending strain of the wheel or shear strain of the rim portion; however, there is a demand to further reduce the influence of wheel load. In view of the above-mentioned problems, an object of the present invention is to provide a lateral force measuring device and a lateral force measuring method that improve the measurement accuracy of lateral force. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, a lateral force measuring device according to one embodiment of the present invention is a lateral force measuring device for measuring the lateral force between a wheel of a railway vehicle and a rail, wherein the wheel has a rim portion provided on the outer peripheral edge thereof and having a tread surface formed thereon, a boss portion provided in the center and to which an axle is attached, and a plate portion provided between the rim portion and the boss portion, and the lateral force measuring device is characterized in that it comprises a plurality of strain gauges that penetrate the plate portion in the direction of the central axis of rotation of the wheel and are affixed to the inner surface of holes arranged within a range of angular positions around the central axis of rotation of the wheel, the strain gauges detecting shear strain of the plate portion caused by the lateral force, and a lateral force calculation unit that calculates the lateral force based on the output of a bridge circuit constituted by the strain gauges. Here, a hole being positioned within a range in which the angular position around the central axis of rotation (hereinafter referred to as the central angle) is within π / 4 rad means that there is a single hole, or that multiple holes are positioned such that at least a portion of all of the holes are within the range of the central angle π / 4 rad (for example, the holes are circular and the center of each hole is within the range of the central angle π / 4 rad). This makes it possible to improve the accuracy of lateral force measurement by suppressing the effect of apparent lateral force caused by strain that occurs when a wheel load is applied, compared to existing lateral force measurement methods that use bending strain of the wheel or are affected by shear strain at points 180 degrees apart around the wheel circumference.

[0010] In the present invention, the plurality of strain gauges forming the bridge circuit may be attached to the inner surface of the same hole. In this case, the lateral force calculation unit may be configured to calculate the lateral force intermittently for each revolution of the wheel. This improves the cross sensitivity ratio of the apparent lateral force due to the wheel load when the contact angle position between the wheel and the rail is at a specific point, thereby improving the measurement accuracy when calculating the lateral force intermittently.

[0011] In the present invention, the hole may have a first hole and a second hole arranged at a distance in the circumferential direction of the wheel, and the multiple strain gauges constituting the bridge circuit may include the strain gauge affixed to the inner surface of the first hole and the strain gauge affixed to the inner surface of the second hole. In this case, the lateral force calculation unit can be configured to continuously calculate the lateral force in response to a circumferential change in a contact point position between the wheel and the rail. This makes it possible to reduce the harmonic components of the cross sensitivity characteristic with respect to wheel load, improve the average cross sensitivity ratio when the contact angle position between the wheel and the rail exists continuously over a specified rotation angle range in the circumferential direction of the wheel, and improve the measurement accuracy when continuously calculating the lateral force in accordance with the rolling of the wheel.

[0012] In the present invention, the lateral pressure calculation unit may be configured to include an offset calculation processing unit that calculates an offset of the output of the bridge circuit based on the output history of the bridge circuit obtained in the wheel inspection test and the output history of the bridge circuit obtained by rolling the wheel. According to this, by appropriately calculating the offset of the output of the bridge circuit caused by the arrangement of the strain gauges peculiar to the present invention and removing it from the output of the bridge circuit, it is possible to ensure the measurement accuracy of the lateral pressure.

[0013] In order to solve the above-described problems, a lateral pressure measurement method according to an aspect of the present invention is a lateral pressure measurement device that measures a lateral pressure between a wheel of a railway vehicle and a rail, wherein the wheel has a rim portion provided at an outer peripheral edge portion and having a tread surface formed thereon, a boss portion provided at a central portion to which an axle is attached, and a plate portion provided between the rim portion and the boss portion. The lateral pressure measurement method is characterized in that a plurality of strain gauges for detecting a shear strain of the plate portion caused by the lateral pressure are arranged in a range where an angular position of the plate portion around the rotation center axis of the wheel is within π / 4 rad and are attached to an inner surface of a hole that penetrates the plate portion in the rotation center axis direction, and the lateral pressure is calculated based on an output of a bridge circuit composed of the strain gauges attached to the inner surface of the hole. According to this, it is possible to obtain substantially the same effects as the effects of the invention related to the above-described lateral pressure measurement device.

Effects of the Invention

[0014] As described above, according to the present invention, it is possible to provide a lateral pressure measurement device and a lateral pressure measurement method with improved measurement accuracy of lateral pressure.

Brief Description of the Drawings

[0015] [Figure 1] It is a diagram showing a configuration of a wheel and an arrangement of strain gauges used in a lateral pressure measurement device and the like of an embodiment. [Diagram 2] It is a diagram showing an arrangement of only the minimum necessary strain gauges for forming a separated bridge circuit among the strain gauges shown in FIG. 1. [Diagram 3] FIG. 1 shows the basic form of a separated bridge circuit for a lateral pressure measurement method utilizing shear strain. [Figure 4] In the lateral pressure measurement method utilizing shear strain, this is a bridge circuit (adjacent hole utilization type) that utilizes strain gauges in adjacent holes. [Diagram 5] 1 is a separated bridge circuit (for bending comparison) using bending strain for comparison of the present invention. [Figure 6] FIG. 13 is a diagram showing the sensitivity characteristics when a lateral force is applied to a basic bridge circuit. [Figure 7] FIG. 13 is a diagram showing the sensitivity characteristics when a lateral pressure is applied in an adjacent hole utilizing bridge circuit. [Figure 8] FIG. 13 is a diagram showing sensitivity characteristics when a lateral pressure is applied in a bridge circuit for bending comparison. [Figure 9] FIG. 13 is a diagram showing sensitivity characteristics when a wheel load is applied in a basic bridge circuit. [Figure 10] FIG. 13 is a diagram showing the sensitivity characteristics when a wheel load is applied in an adjacent hole utilization type bridge circuit. [Figure 11] FIG. 13 is a diagram showing sensitivity characteristics when a wheel load is applied in a bridge circuit for bending comparison. [Figure 12] FIG. 13 is a diagram showing the results of calculating the cross sensitivity ratio in the measurement coverage area, and shows the state when the left-right loading position is −20 mm (opposite the flange side). [Figure 13] FIG. 13 is a diagram showing the results of calculating the cross sensitivity ratio in the measurement coverage area, and shows the state when the left-right load position is +20 mm (flange side). [Figure 14] FIG. 13 is a diagram showing the results of fitting the strain output per unit lateral pressure with Equation 1. [Figure 15] FIG. 13 is a diagram showing the results of fitting the strain output per unit wheel load with Equation 2. [Figure 16] FIG. 13 is a block diagram showing an example of implementation of a filter for removing an offset when the filter is applied to PQ measurement using the intermittent method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of a lateral force measuring device and a lateral force measuring method to which the present invention is applied will be described. First, in the above-mentioned existing lateral force measurement method that utilizes the shear strain of the wheel (the technology described in Patent Document 1), when a wheel load is applied at a position that is 180 degrees different from the position where the strain gauge is attached, a large strain is generated (see Figure 9 described later). In the conventional bridge circuit configuration method, this effect causes a decrease in accuracy, which is a problem. In other words, it is necessary to reduce the cross sensitivity ratio at which apparent lateral force is generated by the wheel load. In the embodiments, the cross-sensitivity ratio is improved.

[0017] The reason for the deterioration of the cross sensitivity ratio is believed to be that when a force is applied to a certain position on the wheel circumference, elastic deformation also occurs at a position that is 180 degrees out of phase with the loaded position. In other words, strains of an order of magnitude that could not be ignored in terms of measurement accuracy were occurring not only in the strain gauge closest to the loaded position, but also in the strain gauge on the other side of the axle, and it is believed that these strains occurred in a direction that worsened the cross sensitivity ratio. This means that if the gauges measuring the strain on the opposite side of the axle can be separated from the bridge circuit, it may be possible to further reduce the cross sensitivity ratio. In this embodiment, such a separated bridge circuit is referred to as a "separated bridge circuit" (to which the present invention is applied), and a bridge circuit incorporating a strain gauge on the opposite side as in the prior art is referred to as a "non-separated bridge circuit" (prior art equivalent to that described in Patent Document 1).

[0018] In order to separate the bridge circuit, the following problems must be solved: To ensure sufficient sensitivity around the entire wheel circumference, as was previously the case, a minimum of four bridge circuits would be required just for measuring lateral force, which means that the number of channels in currently available slip ring devices is insufficient. -The sensitivity characteristics to wheel rotation have a periodic offset, so a new signal processing method needs to be developed.

[0019] Of these issues, the former can be addressed by utilizing wireless digital transmission equipment and achieving multi-channelization. The following mainly describes how to solve the latter problem. Specifically, we will explain below the examination of the bridge circuit configuration after separation, the analysis of sensitivity characteristics by FEM, and the examination of a filter that can handle periodicity accompanied by an offset.

[0020] FIG. 1 is a diagram showing the configuration of a wheel and the arrangement of strain gauges used in a lateral force measuring device and the like according to an embodiment. FIG. 1(a) is a view of a wheel 100 as seen from the axial direction and from the outer side in the vehicle width direction. 1(b) and 1(c) are cross-sectional views taken along the lines bb and cc in FIG. 1(a), respectively. The wheel 100 is, for example, an integrally rolled wheel in which a rim portion 110, a boss portion 120, a plate portion 130, and the like are integrally formed. The PQ wheel set of this embodiment is formed by press-fitting boss portions 120 of a pair of left and right wheels 100 onto both ends of an axle (not shown).

[0021] The rim portion 110 is a tire portion provided on the outer circumferential edge of the wheel 100, and has a tread surface 111, a flange 112, etc. The tread surface 111 is the outer peripheral surface of the rim portion 110, and is the portion that comes into contact with the head of a rail (not shown). The tread 111 has a predetermined tread gradient so that the outside of the vehicle is smaller in diameter than the inside, enabling smooth curved running. The flange 112 is formed so as to protrude radially outward from the end of the tread 111 on the vehicle inner side in the shape of a brim. In FIG. 1(a), the numbers written in the circumferential direction on the rim portion 110 are circumferential position indicators used to indicate loading points in lateral pressure measurement and the like. The position indicators are arranged at equal intervals in the clockwise direction in FIG. 1(a) by dividing the wheel 100 into 32 parts in the circumferential direction.

[0022] The boss portion 120 is provided in the center of the wheel 100 and is a cylindrical portion into which an axle (not shown) is press-fitted. The rim portion 110 and the boss portion 120 are formed to protrude on both sides in the axle direction relative to the plate portion 130.

[0023] The plate portion 130 is a disk-shaped portion provided on the inner diameter side of the rim portion 110 . The plate portion 130 is formed, for example, in a flat plate shape extending along a plane perpendicular to the axial direction of the axle. The boss portion 120 is provided in the center of the plate portion 130 .

[0024] The plate portion 130 has a hole 131 formed therein for attaching a strain gauge. The hole 131 is provided in the middle portion between the inner peripheral edge of the rim portion 110 and the outer peripheral edge of the boss portion 120 in the radial direction of the wheel 100 . The holes 131 are arranged at, for example, eight locations at equal intervals along the circumferential direction of the wheel 100. The holes 131 are formed at positions corresponding to 0, 4, 8, 12, 16, 20, 24, and 28 in the above-mentioned position index. A strain gauge, which will be described below, is attached to the inner peripheral surface of the hole 131.

[0025] Strain gauges 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6A, 6B, 7A, 7B, 8A, and 8B are affixed to the inner circumferential surface of hole 131. The strain gauges 1A and 1B are arranged facing each other in the circumferential direction of the wheel 110 on the inner circumferential surface of a hole 131 provided at a position corresponding to a position index 0 (a phase / angle position around the axle).

[0026] The strain gauges 2A and 2B are arranged on the inner circumferential surface of a hole 131 provided at a location corresponding to the position index 4, facing each other in the circumferential direction of the wheel 110. The strain gauges 3A and 3B are arranged on the inner circumferential surface of a hole 131 provided at a position corresponding to the position index 8, facing each other in the circumferential direction of the wheel 110. The strain gauges 4A and 4B are arranged on the inner circumferential surface of a hole 131 provided at a position corresponding to the position index 12, facing each other in the circumferential direction of the wheel 110. The strain gauges 5A and 5B are arranged on the inner circumferential surface of a hole 131 provided at a position corresponding to the position index 16, facing each other in the circumferential direction of the wheel 110. The strain gauges 6A and 6B are arranged on the inner circumferential surface of a hole 131 provided at a position corresponding to the position index 20, facing each other in the circumferential direction of the wheel 110. The strain gauges 7A and 7B are arranged on the inner circumferential surface of a hole 131 provided at a position corresponding to the position indicator 24, facing each other in the circumferential direction of the wheel 110. The strain gauges 8A and 8B are arranged on the inner circumferential surface of a hole 131 provided at a position corresponding to the position index 28, facing each other in the circumferential direction of the wheel 110.

[0027] In order to adopt a lateral pressure measurement method using shear strain, strain gauges 1A, 1B, 3A, 3B, 5A, 5B, 7A, 7B, 8A, and 8B are provided with three points (three axes) of strain gauges per location, which can be used, for example, for rosette analysis. To distinguish between these, a sub-number is assigned in addition to the main number. As shown in Figures 1(b) and 1(c), the branch number of the strain gauge whose head (pointing axially toward the outer diameter of the wheel) is inclined toward the flange is assigned to 3, the branch number of the central strain gauge used to measure wheel load is assigned to 2, and the branch number of the strain gauge whose head is inclined away from the flange is assigned to 1. In addition, strain gauges 2A, 2B, 4A, 4B, 6A, 6B, 8A, and 8B are uniaxial strain gauges that correspond to branch number 2. (However, when configuring an adjacent hole utilization type bridge circuit, which will be described later, strain gauges 2A and 2B are also triaxial strain gauges.) Each strain gauge associated with branch number 2 constitutes a wheel load bridge circuit in a known continuous wheel load measuring device.

[0028] Further, the wheel 100 is provided with strain gauges 1a, 1a', 3a, 3a', 5a, 5a', 7a, and 7a' which constitute a lateral force measuring device that is a comparative example of the present invention. These strain gauges form a known lateral pressure bridge circuit that measures the lateral pressure based on the bending deformation of the plate portion 130. The strain gauges 1a, 1a', 3a, 3a', 5a, 5a', 7a, and 7a' are disposed on the surface of the plate portion 130 (the side surface of the wheel 110) in an area on the inner diameter side of the hole 131. The strain gauges 1a and 1a' are disposed on the inner diameter side of the hole 131 in which the strain gauges 1A and 1B are provided. The strain gauge 1a is attached to the outer surface of the wheel 110 in the vehicle width direction. The strain gauge 1a' is attached to the inner surface of the wheel 110 in the vehicle width direction. The strain gauge 1a and the strain gauge 1a' are disposed opposite to each other in the direction of the rotation axis of the wheel 110, with the plate portion 130 interposed therebetween.

[0029] The strain gauges 3a and 3a' are disposed on the inner diameter side of the hole 131 in which the strain gauges 3A and 3B are provided. The strain gauge 3a is attached to the outer surface of the wheel 110 in the vehicle width direction. The strain gauge 3a' is attached to the inner surface of the wheel 110 in the vehicle width direction. The strain gauge 3a and the strain gauge 3a' are disposed opposite to each other in the direction of the rotation axis of the wheel 110, with the plate portion 130 interposed therebetween.

[0030] Strain gauges 5a and 5a' are disposed on the inner diameter side of hole 131 in which strain gauges 5A and 5B are provided. The strain gauge 5a is attached to the outer surface of the wheel 110 in the vehicle width direction. The strain gauge 5a' is attached to the inner surface of the wheel 110 in the vehicle width direction. The strain gauge 5a and the strain gauge 5a' are disposed opposite to each other in the direction of the rotation axis of the wheel 110, with the plate portion 130 interposed therebetween.

[0031] The strain gauges 7a and 7a' are disposed on the inner diameter side of the hole 131 in which the strain gauges 7A and 7B are provided. The strain gauge 7a is attached to the outer surface of the wheel 110 in the vehicle width direction. The strain gauge 7a' is attached to the inner surface of the wheel 110 in the vehicle width direction. The strain gauge 7a and the strain gauge 7a' are disposed opposite to each other in the direction of the rotation axis of the wheel 110, with the plate portion 130 interposed therebetween.

[0032] FIG. 2 is a diagram showing the arrangement of only the minimum number of strain gauges required for verifying the separated bridge circuit, among the strain gauges shown in FIG. In the configuration shown in FIG. 2, in order to verify the configuration of a bridge circuit utilizing adjacent holes 131, triaxial strain gauges 2A-1, 2, 3 and 2B-1, 2, 3 are attached at position "4" where a uniaxial strain gauge was to be attached in FIG. 1.

[0033] For comparison, a separate bridge circuit is also constructed for bending strain. In this case, since the attachment method shown in Figure 1 does not allow the construction of a bridge circuit using the 4-gauge method, the attachment positions of the strain gauges are shifted slightly in the circumferential direction of the wheel (left and right direction in Figure 2), and four single-axis strain gauges (two on the front and two on the back) 1a'-1, 1a-2, 1a'-2, 1a-1 are attached to only half of the wheel (the upper half in Figure 2) as shown in Figure 2.

[0034] FIG. 3 is a diagram showing the basic form (basic configuration of the separated type) of a separated bridge circuit for the lateral pressure measurement method utilizing shear strain. The bridge circuit is formed by sequentially connecting strain gauges 1A-1, 1A-3, 1B-1, and 1B-3 in a ring shape. The output of the bridge circuit is the voltage between strain gauges 1A-1 and 1A-3 and the voltage between strain gauges 1B-1 and 1B-3. In the configuration of FIG. 3, the strain gauge in only one hole 131 completes the bridge circuit.

[0035] Figure 4 shows a bridge circuit (adjacent hole utilization type) that utilizes strain gauges of adjacent holes in a lateral pressure measurement method that utilizes shear strain. The configuration of Figure 4 is designed to reduce the harmonic components of the cross-sensitivity characteristics with respect to the axle load. The bridge circuit is configured by sequentially connecting strain gauges 1A-1, 1B-1, 1A-3, 1B-3, 2A-1, 2B-1, 2A-3, and 2B-3 in a ring shape. The output of the bridge circuit is the voltage between strain gauges 1B-1 and 1A-3 and between strain gauges 2A-1 and 2B-3. In the configuration of Figure 4, a bridge circuit is formed by using the strain gauges of two holes 131 (the first hole and the second hole of the present invention) adjacent in the circumferential direction.

[0036] Figure 5 shows a separated bridge circuit using bending strain for comparison. The bridge circuit is configured by sequentially connecting strain gauges 1a′-1, 1a-2, 1a′-2, and 1a-1 in a ring shape. The output of the bridge circuit is the voltage between strain gauges 1a′-1 and 1a-2 and between strain gauges 1a′-2 and 1a-1. Since the configurations shown in Figures 3 to 5 are all bridge circuits based on the four-gauge method, they have a temperature compensation function. In the present invention, the arrangement of the strain gauges is not limited to this embodiment and can be changed as appropriate. However, even in this case, it is preferable to form the bridge circuit only with strain gauges arranged within a range of an angular position around the central axis of the wheel 100 within π / 4 rad.

[0037] The output of each bridge circuit is processed by a lateral pressure calculation unit, which is an arithmetic means, and is used for calculating the lateral pressure Q. The lateral pressure calculation unit can be configured as a computer having, for example, an information processing unit such as a CPU, a storage unit such as a RAM or a ROM, an input / output interface, and a bus connecting these. The lateral force Q may be calculated offline, for example, by recording the bridge circuit output (distortion waveform) measured on board the vehicle and bringing it back to a ground facility. In addition, if the lateral force calculation unit has sufficient computing power, the calculation may be performed in real time on board the vehicle or at a ground facility capable of communicating with the vehicle.

[0038] For the three types of bridge circuits shown in Figures 3 to 5, the sensitivity characteristics when a lateral force Q is applied and the cross sensitivity characteristics when a wheel load P is applied are investigated, and the cross sensitivity ratios of each method are compared using the results. FIG. 6 is a diagram showing the sensitivity characteristics when a lateral force is applied to the basic bridge circuit. FIG. 7 is a diagram showing the sensitivity characteristics when a lateral pressure is applied to the adjacent hole utilization type bridge circuit. FIG. 8 is a diagram showing sensitivity characteristics when a lateral pressure is applied in a bridge circuit for bending comparison. Figures 6 to 8 show the bridge circuit output characteristics when a lateral force equivalent load is applied to 32 test positions on the wheel circumference (expressed as angles on the horizontal axis) with three patterns of lateral force Q of 10 kN, 20 kN, and 30 kN. First, for all three types of bridge circuits, when loading is applied at the same position, it can be confirmed that a bridge circuit output proportional to the lateral force Q is obtained. When the same magnitude of lateral force Q is applied, the amount of strain (sensitivity) is smaller in shear than in bending, but the rate of decrease in sensitivity compared to bending is similar to that of the non-separated bridge circuit described in Patent Document 1.

[0039] As described above, since the bridge circuit configuration is not axially symmetric with respect to the wheel rotation, the zero point of the distortion in the vertical axis direction with respect to the wheel rotation is shifted. Dealing with this shifted zero point poses a challenge in signal processing. In addition, when comparing (a) the basic type and (b) the type utilizing adjacent holes, which are bridge circuits utilizing shear strain, it is found that although there is no significant difference in the absolute value of the strain output, the phase shifts by approximately π / 8 rad in the type utilizing adjacent holes.

[0040] 9 to 11 are diagrams showing cross sensitivity characteristics when a wheel load is applied. FIG. 9 is a diagram showing the sensitivity characteristics when a wheel load is applied in the basic bridge circuit. FIG. 10 is a diagram showing the sensitivity characteristics when a wheel load is applied in an adjacent hole utilization type bridge circuit. FIG. 11 is a diagram showing the sensitivity characteristics when a wheel load is applied in a bridge circuit for bending comparison. 9 to 11 show the bridge circuit output characteristics when a wheel load equivalent to 40 kN is applied to 32 test positions on the circumference of the wheel (indicated by the angle on the horizontal axis). In this case, three patterns are set for the loading position y in the left-right direction (sleeper direction): +20 mm (flange side), 0 mm (tread center), and -20 mm (opposite flange side).

[0041] For the basic type shown in Fig. 9(a), a "dip" where the cross sensitivity is locally reduced can be seen near the angle of 0 rad, just like the non-separated bridge circuit, confirming that the intermittent method is highly effective in reducing the wheel load cross sensitivity. On the other hand, when the loading position (angle) differs by 180 degrees (πrad), the cross sensitivity becomes relatively large. This is believed to be the reason why the cross sensitivity ratio reduction effect is not noticeable in a non-separated bridge circuit.

[0042] For the adjacent hole utilization type (b) shown in Figure 10, it is confirmed that the "dip" in the cross sensitivity near the angle of 0 rad is slightly smaller. A common characteristic of (a), (b), and (c) is that the zero-point shift characteristic (specifically, the angle at which the strain output becomes zero) is slightly different from the lateral pressure sensitivity.

[0043] Finally, the cross sensitivity ratio, which is an index showing the degree to which apparent lateral force Q is generated by the wheel load P, is compared. In a PQ axle using a separate bridge circuit, it is assumed that one bridge circuit will cover measurements in a range of, for example, ±π / 4, based on the position where the strain gauge is attached. Hereinafter, this range will be referred to as the "measurement coverage range." FIG. 12 is a diagram showing the results of calculating the cross sensitivity ratio in the measurement coverage area, and shows the state when the left-right loading position is −20 mm (opposite the flange side). FIG. 13 is a diagram showing the results of calculating the cross sensitivity ratio in the measurement coverage area, and shows the state when the left-right load position is +20 mm (flange side). As mentioned above, the output of the adjacent hole utilization type bridge circuit has a phase shift of approximately π / 8 rad. However, in order to compare the cross sensitivity characteristics within the measurement range, the phases of all bridge circuits are aligned and plotted in Figures 12 and 13. In addition, the condition y=0 mm, where the cross sensitivity itself is small, was excluded from the comparison.

[0044] For the two methods that utilize shear strain (basic type and adjacent hole utilization type), the cross sensitivity ratios within the measurement range are all lower than those of the method that uses bending strain, and a certain degree of reduction in the wheel load cross sensitivity ratio can be confirmed even in the separated bridge circuit. Regarding the effect of reducing the cross sensitivity ratio, when considering the intermittent method, the cross sensitivity ratio at an angle of 0 rad is the most important. Table 1 compares the cross-sensitivity ratios assuming the intermittent method. [Table 1]

[0045] Among the three methods, the one with the smallest cross-sensitivity ratio is the separated basic configuration (a) that utilizes shear strain. Compared to the method (c) that uses bending strain, it is possible to reduce the cross-sensitivity ratio to less than one-third. As for the adjacent hole utilization type (b), the cross sensitivity ratio is lower than that of the method (c) that uses bending strain, but the cross sensitivity ratio is higher than that of the basic separated type configuration (a). In the case of the adjacent hole utilization type of (b), since it requires a large number of strain gauges and can only be realized with an 8-hole type PQ wheel axle in the first place, at least when measuring by the intermittent method, the basic configuration of the separated type is more advantageous.

[0046] Subsequently, assuming that some kind of continuous processing is carried out, the average cross-sensitivity characteristics within the measurement coverage are considered. Table 2 is a table showing the average value of the cross-sensitivity ratio within the measurement coverage.

Table 2

[0047] As described above, when a separated bridge circuit is adopted, the lateral pressure sensitivity characteristic is not a symmetric periodic function centered on the zero point, but a periodic function with an offset. Furthermore, since the offset characteristics are slightly different between the lateral pressure sensitivity and the wheel load cross-sensitivity, it is necessary to separate the "offset to be considered as a sensor" and the "offset to be removed" in consideration of the difference in the offset characteristics.

[0048] Here, as the "offset to be removed", mainly the offset due to the initial load at the zero shift of the dynamic strain measuring instrument and the offset due to the temperature drift of the dynamic strain measuring instrument can be considered. Regarding the latter, in recent high-performance dynamic strain measuring instruments, the need for consideration is gradually decreasing. However, regarding the former, since the vehicle load must be zero-shifted while acting on the wheel, some countermeasures are necessary. Hereinafter, a method of utilizing a sensitivity characteristic model based on a Fourier series will be described as a signal processing framework corresponding to the separated bridge circuit of the embodiment.

[0049] It is assumed that the sensitivity characteristic of the separated bridge circuit is approximated by the Fourier series of Equation 1.

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[0050] Each parameter, including the offset terms, in Equation 1 and Equation 2 is calculated as a value specific to each PQ axle using the results of a verification test (e.g., a static load test) performed on each PQ axle. Using these functions, the wheel load P, and the lateral force Q, the strain output ε can be approximately expressed as in Equation 3.

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[0051] On the other hand, the strain signal obtained by actually rolling the wheel 100 during a running test

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[0052] In this formula, D ε is the sum of the "sensitivity offset to be taken into account as a sensor" and the "offset to be removed." now,

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[0053] Note that this is based on the assumption that the phase during the inspection and the phase of the distortion signal obtained in the running test are aligned, and in actual signal processing, separate phase adjustment is required. Treating Equation 5 as an identity with respect to φ and comparing the constant terms on both sides, we obtain Equation 6.

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[0054] Therefore, the offset term D to be removed r can be expressed as Equation 7.

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[0055] That is, to precisely calculate the offset term to be removed, 1. Total offset amount D contained in the waveform obtained from the running test r 2. Wheel load P and lateral contact position y 3. Lateral pressure Q It is necessary to understand. The first point can be calculated by Fourier transforming the actual waveform or by passing it through a high-pass filter. r =0. Regarding the second point, let's assume

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[0056] By fitting Equation 1 and Equation 2 to the FEM analysis results, the degree of sensitivity offset that should be considered as a sensor was quantitatively evaluated. The evaluations described here are all for the basic form (a) of the separated bridge circuit.

[0057] First, the lateral pressure sensitivity is evaluated. FIG. 14 is a diagram showing the results of fitting the strain output per unit lateral pressure with Equation 1. The maximum order of the Fourier series was set to 11. Table 3 also shows the Fourier series including offsets identified by fitting. [Table 3] Regarding lateral pressure sensitivity, it is found that an offset of approximately 1.65 με occurs per 1 kN of lateral pressure.

[0058] Next, the wheel load cross sensitivity is evaluated. FIG. 15 is a diagram showing the results of fitting the strain output per unit wheel load with Equation 2. The maximum order of the Fourier series was set to 11. Table 4 shows the Fourier coefficients, including offsets, identified by fitting. [Table 4]

[0059] For offset,

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[0060] On the other hand, under the same contact position and load conditions, the apparent lateral pressure using the conventional lateral pressure measurement method utilizing bending strain is estimated to be approximately 4.06 kN. In consideration of the above, in the offset processing of the lateral force measuring bridge output, the lateral force error accompanying the offset of the wheel load cross sensitivity is small enough to be negligible. Furthermore, even without taking into consideration the offset characteristics of the wheel load cross sensitivity, a sufficient apparent reduction in lateral force can be expected, at least in comparison with a lateral force measurement method using bending strain. Therefore, from this point on, the portion dependent on the wheel load P and the lateral contact position y will be ignored, and attention will be focused only on the offset characteristic of the lateral pressure sensitivity.

[0061] If the influence of the wheel load is ignored in Equation 7, Equation 8 is obtained.

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[0062] The offset to be removed D r The estimation procedure is as follows: 1. For example, the wheel rotation angular velocity is estimated using an AR model, and then the distortion waveform for one wheel rotation is extracted using this. 2. The distortion waveform for one wheel revolution is fitted with a Fourier series to obtain the D ε Calculate. Using the results of 3.2 and the static load test results, the average value of lateral force Q per one wheel revolution

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[0063] At present, the wheel rotational angular velocity estimation method using the AR model requires a long calculation time, and therefore it is difficult to execute it at a typical sampling period (for example, approximately 1 kHz) used in road tests. On the other hand, as mentioned above, in PQ measurement, the causes of changes in the offset of the strain signal are thought to be basically the load at the time of zero shift and the temperature drift of the amplifier. To correct this, the offset calculation processing unit does not need to have a high-speed response.

[0064] FIG. 16 is a block diagram showing an implementation example in which a filter for removing an offset is applied to PQ measurement using the intermittent method. The filter section 200 functioning as the correction calculation section of the present invention includes a one-rotation waveform extraction section 210 and an offset calculation processing section 220 . The one-revolution waveform extracting section 210 extracts the bridge circuit output (distorted waveform) digitally converted by the AD converting section 230 for one rotation of the wheel 100. The offset calculation processing section 220 calculates the amount of offset to be removed based on the distorted waveform for one rotation extracted by the one-rotation waveform extraction section 210.

[0065] The offset amount to be removed calculated by offset calculation processing section 220 is converted into analog by DA conversion section 240, and then subtracted by differential amplifier 250 from the distorted waveform output by the bridge circuit. The distorted waveform from which the offset amount to be removed has been subtracted by the differential amplifier 250 is used to calculate the lateral force Q.

[0066] Next, a calculation method that takes into account the effect of changes in the contact position y in the left-right direction will be described. In this embodiment, when the influence of a change in the contact position in the left-right direction is taken into consideration, Equation 7 is used without approximation instead of Equation 8. However, in order to use Equation 7, the average value of lateral force Q over one wheel revolution must be

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[0067] First, the average wheel load per revolution

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[0068] According to the embodiment described above, the following effects can be obtained. (1) By configuring the bridge circuit as a separate type, the effect of the apparent lateral force Q being generated by the strain generated when the wheel load P is applied can be suppressed, and the measurement accuracy of the lateral force Q can be improved, compared to existing lateral force measurement methods such as a method using the bending strain of the wheel 100 or a method (non-separate type) using the shear strain at points 180 degrees apart on the circumference of the wheel 100. (2) In the basic form of the separated bridge circuit, the cross sensitivity ratio of the apparent lateral force Q due to the wheel load P when the contact angle position between the wheel 100 and the rail is at a specific point can be improved, and the measurement accuracy when calculating the lateral force intermittently (discretely) can be improved. (3) In the adjacent hole utilization type of the separated bridge circuit, the harmonic components of the cross sensitivity characteristic with respect to the wheel load are reduced, and the average cross sensitivity ratio is improved when the contact angle position between the wheel and the rail exists continuously over a specified rotation angle range in the circumferential direction of the wheel (within the measurement range). This makes it possible to improve the measurement accuracy when calculating the lateral force continuously in response to the rolling of the wheel, for example by using the new continuous method. (4) By calculating the offset of the bridge circuit output based on the output history of the bridge circuit obtained in the wheel certification test and the output history of the bridge circuit obtained by rolling the wheel, the offset of the bridge circuit output caused by the separate arrangement of the strain gauges unique to this invention can be appropriately calculated and removed from the bridge circuit output, thereby ensuring the accuracy of lateral force measurement.

[0069] (Other embodiments) The present invention is not limited to the above-described embodiment, but various applications and modifications are possible. (1) The shape, structure, material, manufacturing method, number, arrangement, etc. of each component and part that make up the lateral force measuring device and the lateral force measuring method are not limited to the above-described embodiment and can be changed as appropriate. (2) The shape and structure of the wheel, the method of attaching the strain gauges, and the like are not limited to those described in the embodiment, and can be modified as appropriate. (3) The specific calculation methods and formulas in the embodiments are merely examples and can be modified as appropriate. [Explanation of symbols]

[0070] 1A~8B Strain gauges for wheel load and lateral pressure measurement (lateral pressure measurement method using shear strain) 1a~7a Strain gauges for measuring lateral pressure (plate bending) 100 Wheel 110 Rim 111 Tread 112 Flange 120 Boss section 130 Plate section 131 holes 200 Filter section 210 Single rotation waveform extraction section 220 offset calculation processing unit 230 AD conversion unit 240 DA conversion section 250 Differential amplifier

Claims

1. A lateral force measuring device for measuring a lateral force between a wheel of a railway vehicle and a rail, comprising: The wheel is A rim portion provided on an outer peripheral edge portion and having a tread surface; A boss portion provided in the center to which an axle is attached; a plate portion provided between the rim portion and the boss portion, The lateral pressure measuring device is a plurality of strain gauges that are attached to inner surfaces of holes that penetrate the plate portion in a direction of a central axis of rotation of the wheel and are arranged within a range of angular positions of π / 4 rad around the central axis of rotation and detect shear strain of the plate portion caused by the lateral pressure; a lateral pressure calculation unit that calculates the lateral pressure based on an output of a bridge circuit configured with the strain gauges. A lateral pressure measuring device comprising:

2. The plurality of strain gauges constituting the bridge circuit are attached to the inner surface of the same hole. The lateral force measuring device according to claim 1 .

3. The lateral force calculation unit intermittently calculates the lateral force for each rotation of the wheel. The lateral force measuring device according to claim 2 .

4. The holes include a first hole and a second hole arranged at a distance from each other in a circumferential direction of the wheel, The plurality of strain gauges constituting the bridge circuit include the strain gauge attached to the inner surface of the first hole and the strain gauge attached to the inner surface of the second hole. The lateral force measuring device according to claim 1 .

5. The lateral force calculation unit continuously calculates the lateral force in response to a change in a circumferential direction of a contact point position between the wheel and the rail. The lateral force measuring device according to claim 4 .

6. The lateral force calculation unit includes an offset calculation processing unit that calculates an offset of the output of the bridge circuit based on an output history of the bridge circuit obtained in a verification test of the wheel and an output history of the bridge circuit obtained by rolling the wheel. The lateral force measuring device according to any one of claims 1 to 5, characterized in that

7. A lateral force measurement method for measuring a lateral force between a wheel of a railway vehicle and a rail, comprising: The wheel is A rim portion provided on an outer peripheral edge portion and having a tread surface; A boss portion provided in the center to which an axle is attached; a plate portion provided between the rim portion and the boss portion, The lateral pressure measuring method includes: A plurality of strain gauges for detecting shear strain of the plate portion caused by the lateral pressure are arranged in a range of angular positions of the plate portion around the central axis of rotation of the wheel within π / 4 rad and are attached to an inner surface of a hole penetrating the plate portion in the direction of the central axis of rotation; Calculating the lateral pressure based on the output of a bridge circuit formed by the strain gauge attached to the inner surface of the hole. A lateral pressure measurement method comprising:

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