Radio wave shielding structure and chassis dynamometer system

Abstract

The radio wave shielding structure (1) includes a conductive flat belt (3) that is wound around a pair of rollers (2) arranged in parallel under the surface of a metal floor (103) and is exposed from an opening (104) formed in the metal floor (103) so that tires (101 and 102) of a vehicle (100) are placed on the conductive flat belt (3), and a conductive radio wave shielding roller (4) that is arranged between the metal floor (103) and the flat belt (3) in the opening (104), is conductive with the metal floor (103), is in contact with the flat belt (3), and rotates with the movement of the flat belt (3).

Description

[Technical field]

[0001] The present disclosure relates to a radio wave shielding structure and a chassis dynamometer system. [Background technology]

[0002] A chassis dynamometer system is a system for conducting tests related to vehicle running, and for example, measures the force applied from a rotating tire or the peripheral speed of the tire. When testing vehicles with different wheelbases (the distance between the front and rear wheels), the distance between the front and rear wheel rollers must be changed to match the wheelbase in a conventional chassis dynamometer system. In this case, large-scale construction is required, such as digging under the floor and then changing the distance between the front and rear wheel rollers to match the wheelbase.

[0003] As a conventional technique for solving the above problems, for example, there is a vehicle running test device described in Patent Document 1. This vehicle running test device is a chassis dynamometer system equipped with a pair of rollers arranged in parallel under the floor and a flat belt wound around these rollers. Since the difference in wheel base of the vehicle is absorbed by the longitudinal length of the flat belt, there is no need to perform construction work to move the rollers to match the wheel base, and various vehicle models can be tested. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-162912 A Summary of the Invention [Problem to be solved by the invention]

[0005] When performing electromagnetic compatibility (EMC) testing by simulating vehicle running, it is necessary to place a chassis dynamometer system in an anechoic chamber. Meanwhile, anechoic chambers have a metal floor to block electromagnetic noise. When placing a chassis dynamometer system using a flat belt in such an anechoic chamber, it is necessary to form an opening in the metal floor and expose the flat belt through this opening to the anechoic chamber. For this reason, conventional chassis dynamometer systems have a problem in that electromagnetic noise radiated from the drive unit of the flat belt and electromagnetic noise radiated from the equipment under test in the anechoic chamber may propagate inside and outside the anechoic chamber through the opening.

[0006] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a radio wave shielding structure that can block radio waves propagating through an opening formed in a metal floor surface in a room in which a chassis dynamometer system is located. [Means for solving the problem]

[0007] The radio wave shielding structure disclosed herein is a radio wave shielding structure provided in a chassis dynamometer system capable of performing vehicle simulations on a metal floor surface, and comprises: a conductive flat belt that is wound around a pair of rollers arranged in parallel under the metal floor surface and is exposed from an opening formed in the metal floor surface, on which the vehicle tires are placed, and a conductive radio wave shielding roller that is arranged between the metal floor and the flat belt at the opening, is conductive with the metal floor surface, is in contact with the flat belt, and rotates in accordance with the movement of the flat belt. Effect of the Invention

[0008] According to the present disclosure, a conductive flat belt on which a vehicle tire is placed, exposed from an opening formed in the metal floor surface, and a conductive radio wave shielding roller disposed between the metal floor and the flat belt at the opening, conductive with the metal floor and in contact with the flat belt, rotating with the movement of the flat belt, are provided. As a result, the flat belt and the metal floor have the same potential, and the radio wave shielding structure according to the present disclosure can shield radio waves propagating through the opening formed in the metal floor surface in the room in which the chassis dynamometer system is placed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side view that shows a schematic view of a chassis dynamometer system according to a first embodiment. [Diagram 2] 2A and 2B are schematic diagrams showing a vehicle EMC test carried out in an anechoic chamber. [Diagram 3] FIG. 1 is a side view showing a schematic diagram of a radio wave shielding structure according to a first embodiment. [Figure 4] FIG. 1 is a top view diagrammatically illustrating a radio wave shielding structure according to a first embodiment. [Diagram 5] FIG. 2 is a top view diagrammatically showing a modified example (1) of the radio wave shielding structure according to the first embodiment. [Figure 6] FIG. 2 is a side view that illustrates a modified example (1) of the radio wave shielding structure according to the first embodiment. [Figure 7] FIG. 11 is a top view diagrammatically showing a modified example (2) of the radio wave shielding structure according to the first embodiment. [Figure 8] FIG. 11 is a top view diagrammatically illustrating a modified example (3) of the radio wave shielding structure according to the first embodiment. [Figure 9] 9A and 9B are side views that diagrammatically show a modification (4) of the radio wave shielding structure according to the first embodiment. [Figure 10] FIG. 11 is a side view that shows a schematic view of a chassis dynamometer system according to a second embodiment. [Figure 11] FIG. 11 is a side view showing a schematic diagram of a radio wave shielding structure according to a second embodiment. [Figure 12] FIG. 11 is a top view diagrammatically illustrating a radio wave shielding structure according to a second embodiment. [Figure 13] 13A and 13B are front views each showing a schematic view of a roller of a radio wave shielding structure according to the second embodiment. [Figure 14] 14A and 14B are front views each showing a schematic diagram of a radio wave shielding structure according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Embodiment 1 Fig. 1 is a side view showing a schematic diagram of a chassis dynamometer system 200 according to the first embodiment. In Fig. 1, the chassis dynamometer system 200 is a system capable of executing a simulation of a vehicle 100 on the surface of a metal floor 103. For example, the chassis dynamometer system 200 is provided in an anechoic chamber having the metal floor 103. As shown in Fig. 1, the chassis dynamometer system 200 includes a radio wave shielding structure 1 arranged under the metal floor 103.

[0011] The radio wave shielding structure 1 comprises a flat belt 3 wound around a pair of rollers 2 provided for a front tire 101 and a rear tire 102 of a vehicle 100, which is a vehicle under test, and a radio wave shielding roller 4. An opening is formed in the metal floor 103, and the flat belt 3 wound around the roller 2 is exposed from this opening to the inside of the radio wave anechoic chamber.

[0012] 1, the pair of rollers 2 are arranged in parallel under a metal floor 103. Therefore, the flat portion of the flat belt 3 wound around the rollers 2 is approximately parallel to the surface of the metal floor 103. The vehicle 100 is placed in an anechoic chamber with the tires 101 and 102 placed on the flat portion of the flat belt 3.

[0013] 1, the roller 2 rotates in the opposite direction to the tire 101, and the flat belt 3 wound around the roller 2 also rotates accordingly. In this manner, the chassis dynamometer system 200 can simulate a state close to the actual running of the vehicle 100 with the tires 101 and 102 of the vehicle 100 placed on the flat belt 3.

[0014] 1, below the metal floor 103, there is a drive control device for rotating the flat belt 3, i.e., for rotating the rollers 2, and the vehicle 100 is equipped with a device under test that is the subject of the EMC test. The drive control device and the device under test are equipped with electronic circuits, which can become noise sources that generate unnecessary radio waves.

[0015] Meanwhile, as described above, an opening is formed in the metal floor 103 of the anechoic chamber to expose the flat belt 3. A clearance must be provided between the flat belt 3 and the opening of the metal floor 103 so as not to impede the rotational drive of the flat belt 3. For this reason, there is a possibility that the electromagnetic noise generated by the noise sources described above may propagate to the inside and outside of the anechoic chamber through this clearance.

[0016] In order to solve this problem, the radio wave shielding structure 1 is provided with a conductive radio wave shielding roller 4 between the conductive flat belt 3 at the opening of the metal floor 103 and the metal floor 103 . For example, as shown in FIG. 1, the radio wave shielding roller 4 is disposed at an opening of a metal floor 103, at either a portion 104A where the flat belt 3 emerges from under the floor, or at a portion 104B where the flat belt 3 penetrates under the floor, or both.

[0017] The radio wave shielding roller 4 is electrically connected to the metal bed 103 and is arranged so that the roller circumferential surface is in contact with the flat belt 3 and rotates in accordance with the movement of the flat belt 3. 1, for example, when the roller 2 rotates clockwise, the flat belt 3 also rotates clockwise. The radio wave shielding roller 4 in contact with the flat belt 3 rotates counterclockwise in conjunction with the rotation of the flat belt 3.

[0018] At least the surface of the flat belt 3 is conductive, and the radio wave shielding roller 4 is a conductive member that is electrically connected to the metal bed 103. Therefore, when the radio wave shielding roller 4 comes into contact with the flat belt 3, the flat belt 3 is electrically connected to the metal bed 103 via the radio wave shielding roller 4, and has the same potential as the metal bed 103 (ground potential). In this way, the flat belt 3 functions as a large ground plane disposed in the opening formed in the metal floor 103, and is therefore capable of blocking radio waves propagating through the opening.

[0019] Furthermore, even when the flat belt 3 rotates, the radio wave shielding roller 4 rotates with it, thereby maintaining contact with the flat belt 3. Therefore, the radio wave shielding structure 1 can electrically connect the flat belt 3 to the metal bed 103 regardless of the rotation of the flat belt 3. Furthermore, since the radio wave shielding roller 4 rotates while contacting the flat belt 3, there is also an effect that deterioration such as wear is less likely to occur compared to a structure in which a metal piece is simply brought into contact with the rotating flat belt 3.

[0020] Next, an outline of an EMC test using an anechoic chamber equipped with a chassis dynamometer system 200 will be described. FIG. 2A is a top view that typically illustrates an EMC test of a vehicle 100 performed in an anechoic chamber 300. FIG. 2B is a front view that typically illustrates an EMC test of a vehicle 100 performed in the anechoic chamber 300. FIGS. 2A and 2B show the anechoic chamber 300 in which EMC measurement of the vehicle 100 is performed. Although not shown in FIGS. 2A and 2B, the chassis dynamometer system 200 shown in FIG. 1 is assumed to be disposed in the anechoic chamber 300.

[0021] For the EMC measurement, a receiving antenna 302 attached to an antenna mast 301 is used. As shown in Fig. 2A, the receiving antenna 302 is attached to the antenna mast 301 at a position, for example, 3 m above the floor surface. The distance D between the receiving antenna 302 and the vehicle 100 is the measurement distance in the EMC measurement, and is set to a distance of 3 m, 10 m, or the like.

[0022] In the EMC test, for example, the vehicle 100 with tires placed on the flat belt 3 is moved to simulate a running condition, and the radio waves emitted from the vehicle 100 under that condition are measured using the receiving antenna 302. At this time, the measurement distance D may be changed to perform the test. Since the EMC test accurately measures only the radio waves emitted from the vehicle 100, it is necessary to exclude electromagnetic noise from sources other than the vehicle 100. The radio wave shielding structure 1 can block electromagnetic noise passing through an opening formed in the floor surface of the anechoic chamber 300, and therefore can improve the accuracy of the above-mentioned EMC test.

[0023] Next, the radio wave shielding structure 1 will be described in detail. FIG. 3 is a side view showing the radio wave shielding structure 1. FIG. 4 is a top view showing the radio wave shielding structure 1. In FIG. 4, the metal floor 103 is drawn transparently so that the structure under the floor can be seen. Furthermore, FIG. 3 and FIG. 4 show the radio wave shielding structure 1 provided at a portion 104A where the flat belt 3 appears from under the floor in the opening 104 of the metal floor 103. The flat belt 3 is a member made of an elastic material having electrical conductivity. For example, the flat belt 3 may be made by kneading metal powder into an elastic material such as rubber or urethane. The flat belt 3 may be made by coating a layer of an electrically conductive material on the surface of a belt made of an elastic material such as rubber.

[0024] The radio wave shielding roller 4 is a conductive roller that is disposed between the metal bed 103 and the flat belt 3 at the opening 104, is electrically connected to the metal bed 103, and is in contact with the flat belt 3 to rotate with the movement of the flat belt 3. For example, the radio wave shielding roller 4 is attached to the rear surface of the metal bed 103 by a support member 5. The support member 5 is a metal member. One end of the support member 5 is attached to the rear surface of the metal bed 103, and a conductive rotating shaft is provided at the other end. The radio wave shielding roller 4 rotates about this rotating shaft, and is electrically connected to the metal bed 103 via the rotating shaft and the support member 5.

[0025] As shown in FIG. 3, the height h of the support member 5 is designed so that a part of the circumferential surface of the radio wave shielding roller 4 comes into contact with the flat belt 3. As shown in FIG. Furthermore, the radio wave shielding roller 4 may be a single roller extending in the width direction of the flat belt 3, as shown in Fig. 4. The single roller radio wave shielding roller 4 closes the gap between the flat belt 3 and the metal floor 103 in the width direction, so that it is possible to shield unnecessary radio waves propagating through this gap. Although the radio wave shielding roller 4 is provided at the portion 104A where the flat belt 3 emerges from under the floor in the above embodiment, it may be provided at the portion 104B where the flat belt 3 goes under the floor. By providing the radio wave shielding structure 1 in these parts, it is possible to reliably shield unnecessary radio waves. Also, the radio wave shielding structure 1 may be provided for all tires of the vehicle 100.

[0026] Fig. 5 is a top view showing a modified example (1) of the radio wave shielding structure 1, and for ease of explanation, the metal floor 103 is depicted as transparent so that the structure below can be seen. Fig. 6 is a side view showing a modified example (1) of the radio wave shielding structure 1. The modified example (1) of the radio wave shielding structure 1 shown in Figs. 5 and 6 has one or more metal piece portions 6 provided along the longitudinal direction of the flat belt 3 and electrically connected across the opening 104 in the width direction of the flat belt 3.

[0027] These metal piece portions 6 are electrically connected to the metal floor 103 at the ground potential, and therefore function as a ground plane. The metal piece portions 6 are assumed to be plate-shaped members as shown in Fig. 5, but may be metal rods. By providing a plurality of metal piece portions 6 in the opening 104, the opening 104 can be blocked regardless of the rotation of the flat belt 3, and unnecessary radio waves propagating through the opening 104 can be blocked. In the modification (1) shown in FIGS. 5 and 6, the flat belt 3 and the radio wave shielding roller 4 are also electrically connected as shown by the arrow C.

[0028] The interval at which the metal pieces 6 are arranged in the opening 104 is determined so that radio waves of a predetermined frequency do not leak. Radio waves of a frequency higher than the frequency at which this interval is 1 / 2 the wavelength are likely to leak. For example, if the upper limit frequency permitted in the anechoic chamber 300 is 10 GHz, then 1 / 2 the wavelength is 1.5 cm, and so the interval between adjacent metal pieces 6 is set to be shorter than 1.5 cm. In other words, by making this interval shorter than 1.5 cm, radio waves of 10 GHz or less are less likely to leak. However, if the level of electromagnetic noise generated under the floor is low and leakage from this interval is not a problem, it is possible to make the interval longer.

[0029] Fig. 7 is a top view showing a schematic diagram of a modified example (2) of the radio wave shielding structure 1, and for the sake of convenience, the metal floor 103 is depicted as transparent so that the structure below can be seen. The lower view of Fig. 7 is an enlarged view of the part surrounded by the dashed line in the upper view of Fig. 7. As shown in Fig. 7, the radio wave shielding roller 4 may be one or more side rollers 7 or 8 provided between the side of the flat belt 3 and the metal floor 103 at the opening 104. 7, the side roller 7 is a conductive roller that rotates around a rotation axis provided directly on the metal bed 103. The side roller 7 electrically connects the flat belt 3 and the metal bed 103 by contacting the flat belt 3 at the thickness portion.

[0030] 7, the side roller 8 is a conductive roller rotatably mounted on a support member 9 attached to the end face of the opening 104. The support member 9 is a metal member. One end of the support member 9 is attached to the end face of the opening 104, and a conductive rotating shaft is provided on the other end. The side roller 8 rotates around this rotating shaft, and is electrically connected to the metal bed 103 via the rotating shaft and the support member 9. Like the side roller 7, the side roller 8 also contacts the flat belt 3 at a thickness portion thereof, thereby electrically connecting the flat belt 3 and the metal bed 103. By providing the side rollers 7 or 8, it is possible to block unnecessary radio waves propagating through the gap between the side surface of the flat belt 3 and the metal floor 103.

[0031] Fig. 8 is a top view showing a schematic diagram of a modified example (3) of the radio wave shielding structure 1, and for the sake of convenience, the metal floor 103 is drawn transparently so that the structure below the floor can be seen. As shown in Fig. 8, the radio wave shielding roller 4A is a plurality of partial rollers arranged in the width direction of the flat belt 3 and coaxially rotating around the rotating shaft 10. Since the conductive rotating shaft 10 is in electrical conduction with the metal floor 103, each partial roller functions as a conductive roller that is in electrical conduction with the metal floor 103 and in contact with the flat belt 3 to rotate with the movement of the flat belt 3.

[0032] The radio wave shielding roller 4A, which is made up of multiple partial rollers, closes the gap with the metal bed 103 in the width direction of the flat belt 3, making it possible to shield unnecessary radio waves propagating through this gap. In the radio wave shielding roller 4A, the interval d between adjacent partial rollers is a portion that is not in electrical contact with the metal bed 103. Therefore, the interval d is determined to be an interval at which radio waves of a predetermined frequency do not leak. Radio waves of frequencies higher than the frequency at which the interval d is 1 / 2 the wavelength are likely to leak.

[0033] For example, if the upper limit frequency allowed in the anechoic chamber 300 is 10 GHz, then 1 / 2 wavelength is 1.5 cm, and so the distance d is set to be shorter than 1.5 cm. In other words, by making this distance d shorter than 1.5 cm, radio waves below 10 GHz are less likely to leak. However, if the level of electromagnetic noise generated under the floor is low and does not cause any problems if it leaks from this distance, it is possible to make the distance longer.

[0034] Fig. 9A is a side view that shows a schematic diagram of a modified example (4) of the radio wave shielding structure 1. Fig. 9B is a partial side view that shows a schematic diagram of a modified example of the radio wave shielding roller 4. In Fig. 9A and Fig. 9B, the conductive plates 5A and 5B are conductive parts that are electrically connected to the metal bed 103 and are in surface contact with the circumferential surface of the radio wave shielding roller 4. The radio wave shielding roller 4 is electrically connected to the metal bed 103 by the conductive plate 5A or 5B.

[0035] 9A, the conductive plate 5A is a conductive plate-like member having a curved surface with one end attached to the rear surface side of the metal bed 103. The curvature of the curved portion of the conductive plate 5A is formed to match the curvature of the radio wave shielding roller 4, and the two are in contact with each other through their surfaces. 9B, the conductive plate 5B is a conductive block-shaped member having a curved surface with one end attached to the rear surface side of the metal bed 103. The curvature of the curved surface portion of the conductive plate 5B is also formed to match the curvature of the radio wave shielding roller 4, similar to the conductive plate 5A, and the two are in surface contact with each other.

[0036] In this way, the conductive plates 5A and 5B are not in a conductive structure with a conductive rotating shaft, but are in surface contact with the circumferential surface of the radio wave shielding roller 4. This allows the conductive plates 5A and 5B to lower the impedance between them and the radio wave shielding roller 4, enabling stronger grounding. Furthermore, the conductive plates 5A and 5B can maintain a smooth contact state even when the radio wave shielding roller 4 rotates. Although the conductive plates 5A and 5B are provided on the radio wave shielding roller 4 in the above-mentioned embodiment, they may be provided on each partial roller of the radio wave shielding roller 4A described above, or may be made to make surface contact with the peripheral surfaces of multiple partial rollers collectively.

[0037] As described above, the radio wave shielding structure 1 according to the first embodiment includes the conductive flat belt 3 that is wound around a pair of rollers 2 arranged in parallel under the surface of the metal floor 103 and is exposed from an opening 104 formed in the surface of the metal floor 103, on which the tires 101 and 102 of the vehicle 100 are placed, and the conductive radio wave shielding roller 4 that is arranged between the metal floor 103 and the flat belt 3 at the opening 104, is conductive with the metal floor 103, is in contact with the flat belt 3, and rotates with the movement of the flat belt 3. As a result, the flat belt 3 has the same potential as the metal floor 103, and the radio wave shielding structure 1 can shield unnecessary radio waves propagating through the opening 104 formed in the metal floor 103 of the radio wave anechoic chamber.

[0038] In the radio wave shielding structure 1 according to the first embodiment, the radio wave shielding roller 4 is disposed in the opening 104 at either or both of a portion 104A where the flat belt emerges from under the floor and a portion 104B where the flat belt recedes under the floor, and contacts the flat belt 3 in the width direction. This allows the radio wave shielding structure 1 to shield radio waves propagating between the flat belt 3 and the metal floor 103 at the opening 104.

[0039] In the radio wave shielding structure 1 according to the first embodiment, the radio wave shielding roller 4 is a single roller extending in the width direction of the flat belt 3. This ensures that the radio wave shielding roller 4 and the flat belt 3 are electrically connected to each other.

[0040] In the radio wave shielding structure 1 according to the first embodiment, the radio wave shielding roller 4A is a plurality of partial rollers arranged in the width direction of the flat belt 3 and rotating coaxially. This ensures that the radio wave shielding roller 4A and the flat belt 3 are electrically connected to each other.

[0041] The radio wave shielding structure 1 according to the first embodiment is provided with one or more metal piece portions 6 that are provided along the longitudinal direction of the flat belt 3 and electrically connected across the opening 104 in the width direction of the flat belt 3. By providing multiple metal piece portions 6, it is possible to block radio waves that propagate between the lateral sides of the flat belt 3 and the metal floor 103.

[0042] In the radio wave shielding structure 1 according to the first embodiment, the radio wave shielding roller is one or more side rollers 7 and 8 provided between the side surface of the flat belt 3 and the metal floor 103 at the opening 104. By providing the side rollers, radio waves propagating between the lateral side of the flat belt 3 and the metal floor 103 can be shielded.

[0043] The radio wave shielding structure 1 according to the first embodiment includes a conductive plate 5A or 5B that is electrically connected to the metal bed 103 and is in surface contact with the circumferential surface of the radio wave shielding roller 4 or 4A. The radio wave shielding roller 4 or 4A is electrically connected to the metal bed 103 by the conductive plate 5A or 5B. By providing the conductive plate 5A or 5B, the radio wave shielding roller 4 or 4A can be reliably brought into electrical contact with the metal bed 103.

[0044] The chassis dynamometer system 200 according to the first embodiment includes the radio wave shielding structure 1, and therefore can block unwanted radio waves propagating through the opening 104 formed in the metal floor 103 of the radio wave anechoic chamber.

[0045] Embodiment 2 Fig. 10 is a side view showing a schematic diagram of a chassis dynamometer system 200A according to a second embodiment. In Fig. 10, each track plate constituting the crawler belt 11 is shown separated from the others, but in reality, adjacent track plates are connected by pins and bosses. In Fig. 10, the chassis dynamometer system 200A is a system capable of executing a simulation of the vehicle 100 on the surface of the metal floor 103. For example, the chassis dynamometer system 200A is provided in an anechoic chamber having the metal floor 103. As shown in Fig. 10, the chassis dynamometer system 200A includes a radio wave shielding structure 1A arranged under the metal floor 103.

[0046] The radio wave shielding structure 1A includes a track 11 wound around a pair of rollers 2A provided for a front tire 101 and a rear tire 102 of a vehicle 100, which is a vehicle under test, and a radio wave shielding roller 4B. An opening is formed in a metal floor 103, and the track 11 wound around the roller 2A is exposed from this opening to the inside of the radio wave anechoic chamber. At least the surface of the roller 2A is conductive.

[0047] 10, the pair of rollers 2A are arranged in parallel under a metal floor 103. Therefore, the flat portion of the crawler belt 11 wound around the rollers 2A is approximately parallel to the surface of the metal floor 103. The vehicle 100 is placed in an anechoic chamber with the tires 101 and 102 placed on the flat portion of the crawler belt 11.

[0048] For example, by rotating tire 101 in the direction of the arrow shown in Fig. 10, roller 2A rotates in the opposite direction to tire 101, and accordingly, crawler belt 11 wrapped around roller 2A also rotates. In this manner, chassis dynamometer system 200A can simulate a state close to the actual running of vehicle 100 with tires 101 and 102 of vehicle 100 placed on crawler belt 11.

[0049] 10, there is a drive control device for rotating the crawler belt 11, i.e., the rollers 2A, below the metal bed 103, and the device under test that is the subject of the EMC test is mounted on the vehicle 100. The drive control device and the device under test are equipped with electronic circuits, which can become noise sources that generate unnecessary radio waves.

[0050] Meanwhile, as described above, an opening is formed in the metal floor 103 of the anechoic chamber to expose the crawler belt 11. A clearance must be provided between the crawler belt 11 and the opening of the metal floor 103 so as not to interfere with the rotational drive of the crawler belt 11. For this reason, there is a possibility that the electromagnetic noise generated by the noise sources described above will propagate to the inside and outside of the anechoic chamber through this clearance.

[0051] To solve this problem, in the radio wave shielding structure 1A, a conductive radio wave shielding roller 4B is provided between the peripheral surface of the roller 2A and the metal floor 103 at the opening of the metal floor 103. For example, as shown in Fig. 10, the radio wave shielding roller 4B is disposed at either or both of a portion 104A where the crawler belt 11 emerges from under the floor and a portion 104B where the crawler belt 11 penetrates under the floor at the opening of the metal floor 103.

[0052] The radio wave shielding roller 4B is electrically connected to the metal bed 103, and the roller circumferential surface is provided in contact with the conductive circumferential surface portion of the roller 2A, and is configured to rotate with the movement of the crawler belt 11. For example, in Fig. 10, when the roller 2B rotates clockwise, the crawler belt 11 also rotates clockwise. The radio wave shielding roller 4B in contact with the circumferential surface portion of the roller 2A rotates counterclockwise with the rotation of the crawler belt 11.

[0053] The crawler belt 11 is configured by connecting a plurality of crawler plates with pins and bosses, and each crawler plate has electrical conductivity. As described above, the roller 2A is an electrically conductive roller, and the radio wave shielding roller 4B is an electrically conductive member that is electrically connected to the metal bed 103. Therefore, when the radio wave shielding roller 4B comes into contact with the peripheral surface of the roller 2A, the crawler belt 11 is electrically connected to the metal bed 103 via the radio wave shielding roller 4B, and has the same potential (ground potential) as the metal bed 103. In this way, the crawler belt 11 functions as a large ground surface arranged in an opening formed in the metal bed 103, and is therefore capable of shielding radio waves propagating through the opening.

[0054] Furthermore, even if the crawler belt 11 rotates, the radio wave shielding roller 4B rotates with the crawler belt 11, thereby maintaining contact with the peripheral surface of the roller 2A. Therefore, the radio wave shielding structure 1A can electrically connect the crawler belt 11 to the metal bed 103 regardless of the rotation of the crawler belt 11. Furthermore, since the radio wave shielding roller 4B rotates while in contact with the roller 2A, there is an advantage that deterioration such as wear is less likely to occur compared to a structure in which a metal piece is simply in contact with the rotating roller 2A.

[0055] Next, an EMC test using an anechoic chamber equipped with the chassis dynamometer system 200A will be described. The chassis dynamometer system 200A can also be installed in the anechoic chamber 300 shown in Figures 2A and 2B to perform an EMC test on the vehicle 100. Since the EMC test accurately measures only the radio waves emitted from the vehicle 100, it is necessary to eliminate electromagnetic noise from sources other than the vehicle 100. The radio wave shielding structure 1A can block electromagnetic noise passing through an opening formed in the floor surface of the anechoic chamber 300, and therefore can improve the accuracy of the above-mentioned EMC test.

[0056] Next, the radio wave shielding structure 1A will be described in detail. Fig. 11 is a side view showing the radio wave shielding structure 1A. As shown in Fig. 11, the radio wave shielding structure 1A is provided at a portion 104A where the crawler belt 11 appears from under the floor at an opening 104 of a metal floor 103. The radio wave shielding roller 4B is a conductive roller that is disposed between the metal floor 103 and the roller 2A at the opening 104, is electrically conductive with the metal floor 103, and is in contact with the roller 2A to rotate with the movement of the crawler belt 11.

[0057] For example, the radio wave shielding roller 4B is attached to the back surface of the metal bed 103 by a support member 5. The support member 5 is a metal member. One end of the support member 5 is attached to the back surface of the metal bed 103, and a conductive rotating shaft is provided at the other end. The radio wave shielding roller 4B rotates around this rotating shaft, and is electrically connected to the metal bed 103 via the rotating shaft and the support member 5. Moreover, the height h of the support member 5 is designed so that a part of the circumferential surface of the radio wave shielding roller 4B is in contact with the circumferential surface of the roller 2A.

[0058] FIG. 12 is a top view that shows a schematic diagram of the radio wave shielding structure 1A, and for the sake of convenience of explanation, the metal floor 103 is depicted as transparent so that the structure underneath can be seen. Fig. 13A is a front view showing the roller 2A of the radio wave shielding structure 1A with the crawler belt 11 wound around the roller 2A. Fig. 13B is a front view showing the roller 2A of the radio wave shielding structure 1A with the crawler belt 11 removed from the roller 2A. Fig. 14A is a front view showing the radio wave shielding structure 1A with the crawler belt 11 wound around the roller 2A. Fig. 14B is a front view showing the radio wave shielding structure 1A with the crawler belt 11 removed from the roller 2A. 11, 12, 13A, and 14A, the respective track plates constituting the crawler belt 11 are shown separated from each other, but in reality, adjacent track plates are connected by pins and bosses.

[0059] As shown in Figures 12, 13 and 14, the rollers 2A function as drive wheels that drive the crawler belts 11. For example, although not shown in Figures 13B and 14B, a gear for driving the crawler belts 11 may be formed on a portion of the rollers 2A adjacent to the peripheral surface portion 3A around which the crawler belts 11 are wound. Although three crawler belts 11 are wound around a pair of rollers 2A in Figures 12, 13 and 14, a single crawler belt may be used. In addition, the radio wave shielding roller 4B is a conductive multiple partial roller that is arranged between the metal bed 103 and the peripheral portion 3A at the opening 104, is electrically conductive with the metal bed 103, and is in contact with the peripheral portion 3A of the roller 2A to rotate in accordance with the movement of the track 11.

[0060] The radio wave shielding roller 4B, which is made up of a plurality of partial rollers, closes the gap between the metal floor 103 in the width direction of the crawler belt 11, making it possible to shield unnecessary radio waves propagating through this gap. In the radio wave shielding roller 4B, the interval between adjacent partial rollers is a portion that is not electrically connected to the metal floor 103. Therefore, this interval is determined to be an interval that does not allow radio waves of a predetermined frequency to leak. Radio waves of a frequency higher than the frequency at which the interval d is 1 / 2 the wavelength are likely to leak. For example, if the upper limit frequency allowed in the radio wave anechoic chamber 300 is 10 GHz, then 1 / 2 the wavelength is 1.5 cm, and therefore the interval between the partial rollers is set to be shorter than 1.5 cm. In other words, by making this distance shorter than 1.5 cm, radio waves below 10 GHz are less likely to leak. However, if the level of electromagnetic noise generated under the floor is low and does not cause any problems if it leaks from this distance, it is possible to make the distance longer.

[0061] The flat belt 3 shown in the first embodiment is made of rubber, urethane, or the like. Therefore, if the flat belt 3 is lengthened to accommodate the wheelbase of the vehicle 100, it is likely to bend due to its elasticity. In this case, the bending can be reduced by widening the width of the flat belt 3, but the excavation area for arranging the chassis dynamometer system 200 will be wider accordingly.

[0062] In contrast, the total length of the crawler belt 11 can be changed in units of one pitch by adjusting the number of crawler plates used, which has the advantage that it is easy to configure the crawler belt 11 with a length that matches the size of the anechoic chamber 300.

[0063] Although the radio wave shielding roller 4B is provided at the portion 104A where the crawler belt 11 emerges from under the floor in the above embodiment, it may be provided at the portion 104B where the crawler belt 11 penetrates under the floor. By providing the radio wave shielding structure 1A in these portions, it is possible to reliably shield unnecessary radio waves. Also, the radio wave shielding structure 1A may be provided for all tires of the vehicle 100.

[0064] Also, the radio wave shielding roller 4B may be a single roller extending in the width direction of the flat belt 3. For example, the radio wave shielding roller 4B can be configured as a single roller by providing a recess on the peripheral surface of the roller so as to avoid the crawler belt 11. The radio wave shielding roller 4B of a single roller closes the gap with the metal bed 103 in the width direction of the crawler belt 11, and therefore can shield unnecessary radio waves propagating through this gap.

[0065] The radio wave shielding structure 1A may be provided with the metal piece portion 6 shown in FIG. 5 and FIG. The metal piece portion 6 in the radio wave shielding structure 1A is one or more metal piece portions provided along the longitudinal direction of the track 11 and electrically connected across the opening 104 in the width direction of the track 11. These metal piece portions 6 are electrically connected to the metal floor 103, which is at ground potential, and therefore function as a ground surface. The metal piece portion 6 is assumed to be a plate-shaped member, but may also be a metal rod. By providing multiple metal piece portions 6 at the opening 104, the opening 104 can be blocked regardless of the rotation of the track 11, and unnecessary radio waves propagating through the opening 104 can be blocked.

[0066] In the radio wave shielding structure 1A, the interval at which the metal pieces 6 are arranged in the opening 104 is determined so that radio waves of a predetermined frequency do not leak. Radio waves of a frequency higher than the frequency at which this interval is 1 / 2 the wavelength are likely to leak. For example, if the upper limit frequency permitted in the radio wave anechoic chamber 300 is 10 GHz, 1 / 2 the wavelength is 1.5 cm, so the interval between adjacent metal pieces 6 is set to be shorter than 1.5 cm. In other words, by making this interval shorter than 1.5 cm, radio waves of 10 GHz or less are less likely to leak. Note that if the level of electromagnetic noise generated under the floor is low and leakage from this interval is not a problem, it is possible to make the interval longer.

[0067] Moreover, the radio wave shielding structure 1A may be provided with side rollers as shown in FIG. That is, the radio wave shielding roller 4B may be one or more side rollers 7 or 8 provided between the side surface of the crawler belt 11 and the metal floor 103 at the opening 104. 7, the side roller 7 is a conductive roller that rotates about a rotation axis provided directly on the metal bed 103. The side roller 7 contacts the crawler belt 11 at the thickness portion thereof, thereby electrically connecting the crawler belt 11 and the metal bed 103.

[0068] As shown in the lower diagram of Fig. 7, the side roller 8 is a conductive roller rotatably mounted on a support member 9 attached to the end face of the opening 104. The support member 9 is a metal member. One end of the support member 9 is attached to the end face of the opening 104, and a conductive rotating shaft is provided on the other end. The side roller 8 rotates around this rotating shaft, and is electrically connected to the metal bed 103 via the rotating shaft and the support member 9. Like the side rollers 7, the side rollers 8 also come into contact with the crawler belt 11 at the thickness portion thereof, thereby electrically connecting the crawler belt 11 and the metal bed 103. By providing the side rollers 7 or 8, it is possible to block unnecessary radio waves propagating through the gap between the side surface of the crawler belt 11 and the metal floor 103.

[0069] 9A and 9B may be provided to the radio wave shielding structure 1A. The conductive plates 5A and 5B are conductive plates that are electrically connected to the metal bed 103 and are in surface contact with the circumferential surface of the radio wave shielding roller 4B. The radio wave shielding roller 4B is electrically connected to the metal bed 103 by the conductive plate 5A or 5B.

[0070] 9A, the conductive plate 5A is a conductive plate-like member having a curved surface with one end attached to the rear surface side of the metal bed 103. The curvature of the curved surface portion of the conductive plate 5A is formed to match the curvature of the radio wave shielding roller 4B, and the two are in surface contact with each other. 9B, the conductive plate 5B is a conductive block-shaped member having a curved surface with one end attached to the rear surface side of the metal bed 103. The curvature of the curved surface portion of the conductive plate 5B is also formed to match the curvature of the radio wave shielding roller 4B, similar to the conductive plate 5A, and the two are in surface contact with each other.

[0071] In this way, the conductive plates 5A and 5B are not in a conductive structure with a conductive rotating shaft, but are in surface contact with the circumferential surface of the radio wave shielding roller 4B. This allows the conductive plates 5A and 5B to reduce the impedance between them and the radio wave shielding roller 4B, enabling stronger grounding. Furthermore, the conductive plates 5A and 5B can maintain a smooth contact state even when the radio wave shielding roller 4B rotates.

[0072] As described above, the radio wave shielding structure 1A according to the second embodiment includes the crawler belt 11, which is wound around a pair of rollers 2A arranged in parallel under the surface of the metal floor 103 and is exposed from an opening 104 formed in the metal floor 103, on which the tires 101 and 102 of the vehicle 100 are placed, the conductive peripheral surface portion 3A provided on the peripheral surface of one or both of the pair of rollers 2A, and the conductive radio wave shielding roller 4B, which is arranged between the metal floor 103 and the peripheral surface portion 3A at the opening 104, is electrically connected to the metal floor 103, and is in contact with the peripheral surface portion 3A so as to rotate with the movement of the crawler belt 11. As a result, the radio wave shielding structure 1A can shield radio waves propagating through the opening 104 between the peripheral surface portion 3A of the roller 2A provided in the chassis dynamometer system 200 and the metal floor 103.

[0073] In the radio wave shielding structure 1A according to the second embodiment, the radio wave shielding rollers 4B are disposed at either or both of a portion 104A where the crawler belt 11 emerges from under the floor and a portion 104B where the crawler belt 11 recedes under the floor, at the opening 104. This allows the radio wave shielding structure 1A to shield radio waves propagating through the opening 104 between the peripheral portion 3A and the metal floor 103.

[0074] In the radio wave shielding structure 1A according to the second embodiment, the radio wave shielding roller 4B is a single roller extending in the width direction of the roller 2A around which the crawler belt 11 is wound. This ensures that the radio wave shielding roller 4B is electrically connected to the peripheral surface portion 3A.

[0075] In the radio wave shielding structure 1A according to the second embodiment, the radio wave shielding roller 4B is a plurality of partial rollers arranged in the width direction of the roller 2A around which the crawler belt 11 is wound and rotating coaxially. This ensures that the radio wave shielding roller 4B is electrically connected to the peripheral surface portion 3A.

[0076] The radio wave shielding structure 1A according to the second embodiment is provided with one or more metal piece portions 6 that are provided along the longitudinal direction of the crawler belt 11 and are electrically connected across the opening 104 in the width direction of the crawler belt 11. By providing the multiple metal piece portions 6, radio waves propagating through the opening 104 can be shielded.

[0077] The radio wave shielding structure 1A according to the second embodiment includes a conductive plate 5A or 5B that is electrically connected to the metal bed 103 and in surface contact with the circumferential surface of the radio wave shielding roller 4B. The radio wave shielding roller 4B is electrically connected to the metal bed 103 by the conductive plate 5A or 5B. The conductive plate 5A or 5B is in surface contact with the circumferential surface portion 3A of the radio wave shielding roller 4B, thereby increasing the contact area between them. This allows the radio wave shielding structure 1A to reliably establish electrical conduction between the radio wave shielding roller 4B and the metal bed 103.

[0078] In the radio wave shielding structure 1A according to the second embodiment, the crawler belt 11 is conductive. By electrically connecting the conductive crawler belt 11 to the metal floor 103, the floor surface area including the opening 104 becomes a large ground, so that unnecessary radio waves propagating to the outside and inside of the anechoic chamber through the opening 104 can be shielded.

[0079] In the radio wave shielding structure 1A according to the second embodiment, the radio wave shielding roller 4B is one or more side rollers provided between the side surface of the crawler belt 11 and the metal floor 103 at the opening 104. This makes it possible to reliably establish electrical continuity between the radio wave shielding roller 4B and the crawler belt 11.

[0080] The chassis dynamometer system 200A according to the second embodiment includes the radio wave shielding structure 1A, and therefore can block unwanted radio waves propagating through the opening 104 formed in the metal floor 103 of the radio wave anechoic chamber.

[0081] It is possible to combine the embodiments, modify any of the components of the embodiments, or omit any of the components of the embodiments. [Industrial Applicability]

[0082] The radio wave shielding structure according to the present disclosure can be used, for example, in a chassis dynamometer system arranged in an anechoic chamber. [Explanation of symbols]

[0083] 1,1A radio wave shielding structure, 2,2A,2B roller, 3 flat belt, 3A peripheral portion, 4,4A,4B radio wave shielding roller, 5,9 support member, 5A,5B conductive plate, 6 metal piece portion, 7,8 side roller, 10 rotating shaft, 11 track, 100 vehicle, 101,102 tire, 103 metal floor, 104 opening, 104A,104B portion, 200,200A chassis dynamometer system, 300 radio wave anechoic chamber, 301 antenna mast, 302 receiving antenna.

Claims

1. A radio wave shielding structure provided in a chassis dynamometer system capable of performing a vehicle simulation on a metal floor surface, a conductive flat belt that is wound around a pair of rollers arranged in parallel under the metal floor surface and is exposed through an opening formed in the metal floor surface and on which the vehicle tires are placed; and a conductive radio wave shielding roller that is disposed between the metal bed and the flat belt at the opening, is electrically conductive with the metal bed, and is in contact with the flat belt and rotates with the movement of the flat belt. A radio wave shielding structure characterized by:

2. The radio wave shielding roller is disposed in the opening at either or both of a portion where the flat belt emerges from under the floor and a portion where the flat belt retreats under the floor, and is in contact with the flat belt in a width direction.

2. The radio wave shielding structure according to claim 1.

3. The radio wave shielding roller is a single roller extending in the width direction of the flat belt.

3. The radio wave shielding structure according to claim 2.

4. The radio wave shielding roller is a plurality of partial rollers arranged in the width direction of the flat belt and rotating coaxially.

3. The radio wave shielding structure according to claim 2.

5. The flat belt has one or more metal pieces that are provided along the longitudinal direction of the flat belt and electrically connect to the opening in the width direction of the flat belt.

5. The radio wave shielding structure according to claim 1, wherein the first insulating layer is a conductive layer.

6. The radio wave shielding roller is one or more side rollers provided between the side of the flat belt and the metal bed at the opening.

5. The radio wave shielding structure according to claim 1, wherein the first insulating layer is a conductive layer.

7. a conductive portion that is electrically conductive with the metal bed and in surface contact with a peripheral surface of the radio wave shielding roller, The radio wave shielding roller is electrically connected to the metal bed by the conductive portion.

5. The radio wave shielding structure according to claim 1, wherein the first insulating layer is a conductive layer.

8. A radio wave shielding structure provided in a chassis dynamometer system capable of performing a vehicle simulation on a metal floor surface, a track that is wound around a pair of rollers arranged in parallel under the metal floor surface and is exposed through an opening formed in the metal floor surface, on which tires of the vehicle are placed; a conductive peripheral portion provided on a peripheral surface of one or both of the pair of rollers; a conductive radio wave shielding roller disposed between the metal bed and the roller at the opening, electrically connected to the metal bed, and in contact with the peripheral surface portion to rotate with the movement of the crawler belt; A radio wave shielding structure characterized by:

9. The radio wave shielding roller is disposed at the opening at either or both of a portion where the crawler belt emerges from under the floor and a portion where the crawler belt penetrates under the floor.

9. The radio wave shielding structure according to claim 8.

10. The radio wave shielding roller is a single roller extending in the width direction of the roller around which the crawler belt is wound.

10. The radio wave shielding structure according to claim 9.

11. The radio wave shielding roller is a plurality of partial rollers arranged in the width direction of the roller around which the crawler belt is wound and rotating coaxially.

10. The radio wave shielding structure according to claim 9.

12. One or more metal pieces are provided along the longitudinal direction of the track and electrically connect across the opening in the width direction of the track. The radio wave shielding structure according to any one of claims 8 to 11.

13. a conductive portion that is electrically conductive with the metal floor surface and in surface contact with the peripheral surface of the radio wave shielding roller; The radio wave shielding roller is electrically connected to the metal bed by the conductive portion. The radio wave shielding structure according to any one of claims 8 to 11.

14. The track is conductive. The radio wave shielding structure according to any one of claims 8 to 11.

15. The radio wave shielding roller is one or more side rollers provided between the side of the crawler belt and the metal floor at the opening.

15. The radio wave shielding structure according to claim 14.

16. A radio wave shielding structure according to claim 1 or 8 is provided. A chassis dynamometer system comprising:

Images