Centrifugal load testing apparatus

Abstract

In a centrifugal loading test apparatus that uses a refrigerant to cool a test specimen, the cooling function is maintained by ensuring a flow path for the refrigerant even when the bucket in which the test specimen is placed is oscillating. [Solution] A centrifugal load testing apparatus comprising a refrigerant pump and a refrigerant flexible pipe, wherein the refrigerant pump is connected to a predetermined refrigerant circulation path including the refrigerant flexible pipe, the refrigerant flexible pipe is positioned between a rotating arm side flexible pipe connection and a bucket side flexible pipe connection, the rotating arm side flexible pipe connection is positioned above the bucket side flexible pipe connection, the rotating arm side flexible pipe connection and the bucket side flexible pipe connection are positioned so that when the rotating arm is stopped they face outward in the direction of the rotational radius of the rotating arm, and the refrigerant supplied from the refrigerant pump is configured to flow from the rotating arm side flexible pipe connection towards the bucket side flexible pipe connection.

Description

Technical Field

[0001] The present disclosure relates to a centrifugal loading test device.

Background Art

[0002] There is a centrifugal loading test device including a columnar rotating shaft installed in the vertical direction and a rotating arm attached to rotate around this rotating shaft. A test specimen is installed at the tip of this rotating arm, and by rotating the rotating arm, a centrifugal force about 100 to 200 times the gravity is applied to the test specimen. The centrifugal loading test device can simulate phenomena with a reduced scale reciprocal of the centrifugal force by using soil as a test specimen and applying a centrifugal acceleration. Further, the centrifugal loading test device can be used as a ground deterioration device that performs freezing and thawing to simulate changes in soil properties and simultaneously adds a deterioration solution to the soil to simulate chemical changes in the soil. According to such a ground deterioration device, the ground behavior considering long-term changes in soil properties can be experimentally investigated in a short time.

[0003] Patent Document 1 discloses a centrifugal loading device capable of cooling a test body, in which a refrigerant circulation pump and a refrigerant tank are installed near the vertical axis in a rotating arm, and a heat exchanger of the test body installed at the tip of the rotating arm, a heat exchanger of the refrigerant tank, and the refrigerant circulation pump are connected in a series of closed circuits by refrigerant pipes. The refrigerant circulation pump and an external power source means for driving the same are connected via a rotary joint provided on the vertical axis, and signal lines and control lines are connected to an external control means and recording and display means via a slip ring provided on the vertical axis.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The centrifugal loading device described in Patent Document 1 draws refrigerant into a rotating arm from the outside via a rotary joint provided at the upper end of the vertical axis. In Patent Document 1, although the refrigerant piping layout is schematically illustrated, it is unclear whether the flow path of the refrigerant can be secured against the oscillation of the test specimen.

[0006] The purpose of this disclosure is to ensure a flow path for the refrigerant and maintain the cooling function in a centrifugal loading test apparatus having a configuration that cools a test specimen using a refrigerant, even when the bucket in which the test specimen is placed is oscillating. [Means for solving the problem]

[0007] The centrifugal load testing apparatus of this disclosure comprises a rotating shaft, a rotating arm rotatable about the rotating shaft, a bucket having a configuration in which a test specimen can be placed, a motor for rotating the rotating shaft, a refrigerant pump, and a refrigerant flexible pipe, wherein the rotating arm has a swing-up axis, the bucket is rotatable about the swing-up axis, the refrigerant pump is connected to a predetermined refrigerant circulation path including a refrigerant flexible pipe, the rotating arm has a rotating arm-side refrigerant piping which is part of the predetermined refrigerant circulation path, the bucket has a bucket-side refrigerant piping which is part of the predetermined refrigerant circulation path, and the rotating arm-side refrigerant piping is connected to the rotating arm-side flexible pipe The bucket-side refrigerant piping has a connection section, the bucket-side flexible pipe connection section has a bucket-side flexible pipe connection section, the flexible pipe for the refrigerant is positioned between the rotating arm-side flexible pipe connection section and the bucket-side flexible pipe connection section, the rotating arm-side flexible pipe connection section is positioned above the bucket-side flexible pipe connection section, and the rotating arm-side flexible pipe connection section and the bucket-side flexible pipe connection section are positioned so that when the rotating arm is stopped, they face outward in the direction of the rotational radius of the rotating arm, and the refrigerant supplied from the refrigerant pump is configured to flow from the rotating arm-side flexible pipe connection section toward the bucket-side flexible pipe connection section. [Effects of the Invention]

[0008] According to this disclosure, in a centrifugal loading test apparatus having a configuration that cools a test specimen using a refrigerant, even if the bucket in which the test specimen is placed oscillates, the flow path of the refrigerant can be secured and the cooling function can be maintained. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic front view showing a centrifugal force loading test apparatus according to an embodiment. [Figure 2] This is a front view showing the bucket 9a, the flexible refrigerant pipe 7, etc., when the rotating arm 2 in Figure 1 is stopped. [Figure 3] Figure 1 is a front view showing the bucket 9a, the flexible refrigerant pipe 7, etc., in the state where the rotating arm 2 is rotating. [Figure 4] Figure 1 is a schematic front view showing a modified example of the centrifugal force loading test apparatus. [Modes for carrying out the invention]

[0010] This disclosure relates to a cooling structure for a centrifugal load testing apparatus.

[0011] The embodiments relating to this disclosure will be described below with reference to the drawings.

[0012] Figure 1 is a schematic front view showing a centrifugal force loading test apparatus according to an embodiment.

[0013] In this figure, the centrifugal load testing apparatus 100 comprises a rotating shaft 1, a rotating arm 2, buckets 9a and 9b, and a motor 15. The centrifugal load testing apparatus 100 also comprises a refrigerant pump 4, refrigerant piping 6 (steel pipe), and a flexible refrigerant pipe 7 that is flexible and deformable. A rotary joint 5 is built into the rotating shaft 1. A refrigerant flow path 8 is provided in the rotary joint 5.

[0014] The refrigerant piping 6 is connected from the refrigerant pump 4 to the side of the rotary joint 5. The refrigerant flowing in from the side of the rotary joint 5 flows into the refrigerant flow path 8. This configuration allows the refrigerant piping 6 to be shortened.

[0015] The rotating arm 2 rotates around the rotation axis 1 and is configured to apply centrifugal acceleration to the test specimens 3 in buckets 9a and 9b. Buckets 9a and 9b are supported so as to be rotatable around the swing axes 10a and 10b of the rotating arm 2, respectively. Test specimens 3 can be placed in buckets 9a and 9b. When centrifugal acceleration is applied to buckets 9a and 9b, buckets 9a and 9b are swung upward in the direction of the rotation radius of the rotating arm 2. As a result, the test specimens 3 placed in buckets 9a and 9b can be tested under conditions where a large downward gravitational force is always acting on them at the time of installation.

[0016] In addition, a counterweight may be placed in either bucket 9a or 9b instead of the test specimen 3.

[0017] The motor 15 is connected to the rotating shaft 1 via a right-angle gear. By driving the motor 15, the rotating shaft 1 and the rotating arm 2 can be rotated.

[0018] The refrigerant pump 4 has a tank for storing refrigerant. The refrigerant is supplied from the refrigerant pump 4 to the test specimens 3 in buckets 9a and 9b via refrigerant piping 6, refrigerant flow path 8, and refrigerant flexible pipe 7, and is configured to return to the tank of the refrigerant pump 4 via return piping (not shown). With this configuration, the refrigerant circulates between the refrigerant pump 4 and buckets 9a and 9b, allowing the test specimens 3 to be cooled. Heat exchange can occur between the test specimens 3 and the refrigerant on buckets 9a and 9b, allowing the test specimens 3 to be cooled.

[0019] In summary, the refrigerant pump 4 is connected to a predetermined refrigerant circulation passage including the refrigerant flexible pipe 7. Here, the "predetermined refrigerant circulation passage" refers to a series of circulation passages through which the refrigerant is discharged from the refrigerant pump 4, supplied to the buckets 9a and 9b, and then refluxed. Therefore, the predetermined refrigerant circulation passage includes the refrigerant pipe 6 disposed between the refrigerant pump 4 and the side surface portion of the rotary joint 5.

[0020] In this figure, the refrigerant pump 4 is installed on the floor of the upper floor where the rotary arm 2, the motor 15, etc. are installed, rather than inside the rotating shaft 1.

[0021] The refrigerant pipe 6 of the rotary arm 2 and the test specimen 3 of the bucket 9a are connected by the refrigerant flexible pipe 7. The refrigerant flexible pipe 7 is arranged so that the refrigerant flows counterclockwise in the figure. In other words, the refrigerant flows into the refrigerant flexible pipe 7 from the refrigerant pipe 6 in a substantially horizontal direction, passes above the lifting shaft 10a, passes to the left in the figure of the lifting shaft 10a (outside the rotation radius direction of the rotary arm 2), and then is configured to flow into the test specimen 3 of the bucket 9a. With this configuration, when the bucket 9a swings up due to centrifugal force, the refrigerant flexible pipe 7 can be deformed to follow and ensure the refrigerant circulation passage.

[0022] The refrigerant flexible pipe 7 is preferably a resin hose resistant to cooling, such as a hose made of thermoplastic elastomer (PTFE, polyurethane, nylon, polyolefin, etc.), or a SUS blade hose having a vacuum double structure.

[0023] The refrigerant stored in the tank is a fluorine-based liquid and is cooled to about -60°C. As the refrigerant, for example, Novec TM 7200 (manufactured by 3M) is preferably used.

[0024] In cooling the test specimen 3 with the refrigerant, it is important to reduce heat loss. The main causes of heat loss are frictional heat generated at the rotary joint 5 and external heat flowing into the refrigerant through the refrigerant circulation channels (refrigerant piping 6, refrigerant channel 8, etc.).

[0025] Figure 2 is a front view showing the bucket 9a, the flexible refrigerant pipe 7, etc., in the state where the rotating arm 2 of Figure 1 is stopped.

[0026] In Figure 2, since no centrifugal force acts on the bucket 9a, the test specimen 3 placed in the bucket 9a is located below the swing axis 10a.

[0027] A refrigerant supply pipe 60 (rotating arm side refrigerant pipe) is fixed to the rotating arm 2. On the other hand, a refrigerant supply pipe 62 (bucket side refrigerant pipe) is fixed to the bucket 9a. A flexible pipe 7 for refrigerant is connected to the flexible pipe connection part 60a (rotating arm side flexible pipe connection part), which is the end of the refrigerant supply pipe 60. A flexible pipe 7 for refrigerant is also connected to the flexible pipe connection part 62a (bucket side flexible pipe connection part), which is the end of the refrigerant supply pipe 62. In other words, the flexible pipe 7 for refrigerant is positioned between the flexible pipe connection part on the rotating arm side and the flexible pipe connection part on the bucket side. The flexible pipe 7 for refrigerant is curved so as to be convex outward in the direction of the rotational radius of the rotating arm 2. The flexible pipe connection part 60a is positioned above the flexible pipe connection part 62a.

[0028] Both the flexible pipe connection sections 60a and 62a are positioned to face outward in the radial direction of rotation of the rotating arm 2 when the rotating arm 2 is stopped. The refrigerant supplied from the refrigerant pump 4 (see Figure 1) is configured to flow from the flexible pipe connection section 60a towards the flexible pipe connection section 62a.

[0029] In Figure 2, the flexible pipe connections 60a and 62a are positioned so that the refrigerant flows horizontally. In other words, the flow of refrigerant in the flexible pipe connections 60a and 62a is parallel and in opposite directions. Both ends of the refrigerant flexible pipe 7 are slightly bent. This bent shape is not a problem as long as the radius of curvature, which is the amount of bending, is greater than the radius of curvature that is permissible for the refrigerant flexible pipe 7 from the standpoint of durability, etc.

[0030] Figure 3 is a front view showing the bucket 9a, the flexible refrigerant pipe 7, etc., in the state in which the rotating arm 2 of Figure 1 is rotating.

[0031] In Figure 3, centrifugal force acts on the bucket 9a, causing the test specimen 3 placed in the bucket 9a to be swung upward and positioned to the left of the swing axis 10a in the figure (outside in the direction of the rotational radius of the rotating arm 2). Consequently, the flexible pipe connection 62a is oriented vertically upward. The ends of the refrigerant flexible pipe 7 are approximately parallel to the flexible pipe connection 60a and 62a, respectively. However, the refrigerant flexible pipe 7 located near the flexible pipe connection 62a is effectively pulled to the left in the figure due to the acceleration caused by the centrifugal force, resulting in the refrigerant flexible pipe 7 becoming convex to the left in the figure. Therefore, the end of the refrigerant flexible pipe 7 located near the flexible pipe connection 62a has a slightly bent shape.

[0032] Furthermore, the flexible refrigerant tube 7 protrudes to the left in the diagram and is in contact with the upper surface (right end in the diagram) of the test specimen 3. To prevent the flexible refrigerant tube 7 from directly contacting the test specimen 3 due to centrifugal force, it is desirable to be able to install a top plate (lid) on the upper surface of the test specimen 3. In this case, the top plate supports the flexible refrigerant tube 7, mitigates deformation due to centrifugal force, and prevents damage to the test specimen 3, the flexible refrigerant tube 7, etc.

[0033] Figure 4 is a schematic front view showing a modified example of a centrifugal load testing apparatus.

[0034] The difference between this figure and Figure 1 is that a top plate 403 (lid) is installed on the top surface of the test specimen 3. In other words, Figure 4 illustrates the desirable configuration described above. The configuration other than the top plate 403 is the same as in Figure 1, so its explanation is omitted.

[0035] In summary, as shown in Figure 2, when the rotating arm 2 is stopped, both the flexible pipe connection sections 60a and 62a are positioned so that their openings face outward in the direction of the rotational radius of the rotating arm 2. This configuration prevents the flexible pipe 7 for the refrigerant from bending and collapsing, and ensures a refrigerant circulation path.

[0036] If, when the rotating arm 2 is stopped, the openings of the flexible pipe connection parts 60a and 62a are positioned perpendicular to the rotational radius direction of the rotating arm 2, then in order to position the refrigerant flexible pipe 7 counterclockwise in the figure, it becomes necessary to bend the refrigerant flexible pipe 7 at the openings of the flexible pipe connection parts 60a and 62a. In this case, it will bend further due to the action of centrifugal force.

[0037] Furthermore, the refrigerant passes above the swing-up shaft 10a, then to the left of the swing-up shaft 10a in the diagram (outside in the radial direction of the rotating arm 2), and then flows into the test specimen 3 in the bucket 9a. As a result, when the bucket 9a is swung up by centrifugal force, the flexible refrigerant pipe 7 is connected to the flexible pipe connection parts 60a and 62a without bending, as shown in Figure 3. Therefore, the refrigerant flexible pipe 7 is not crushed, and a circulation path for the refrigerant can be secured.

[0038] In contrast, if we were to arrange the flexible refrigerant pipes 7 in Figures 1-3 so that the refrigerant flows clockwise, the following problems would arise.

[0039] If the openings of the flexible pipe connection parts 60a and 62a are positioned to the left in the diagram, as in Figure 2, then in order to arrange the refrigerant flexible pipe 7 clockwise in the diagram, it becomes necessary to bend the refrigerant flexible pipe 7 at a right angle.

[0040] To avoid this, for example, if the opening of the flexible pipe connection part 60a is oriented downwards in the figure and the opening of the flexible pipe connection part 62a is oriented to the right in the figure, then when the rotating arm 2 rotates, the openings of both the flexible pipe connection parts 60a and 62a will be oriented downwards in the figure, and the refrigerant flexible pipe 7 will bend at the flexible pipe connection part 60a due to the action of centrifugal force.

[0041] Although there are several other possible orientations for the openings of the flexible pipe connection sections 60a and 62a, in any case, problems arise if the refrigerant flexible pipes 7 are arranged clockwise in the diagram.

[0042] The relationship between arranging the refrigerant flexible pipe 7 counterclockwise in the figure and the bucket 9a swinging clockwise in the figure due to centrifugal force is considered favorable from the viewpoint of preventing bending of the refrigerant flexible pipe 7.

[0043] The effects of this disclosure are summarized below.

[0044] According to this disclosure, by installing the refrigerant pump externally, it becomes easier to enlarge the refrigerant pump compared to a structure in which it is installed inside the equipment. This makes it possible to increase the discharge capacity of the refrigerant pump, and it also becomes easier to further lower the temperature of the discharged refrigerant, thereby improving cooling performance.

[0045] According to this disclosure, the difference in shape of the refrigerant flexible pipe when the rotating arm is stopped and when it is rotating, that is, the difference in the length required for the refrigerant flexible pipe before and after the bucket swings up, can be reduced, eliminating the need to leave an unnecessary margin in the length of the refrigerant flexible pipe. As a result, the length of the flow path for supplying the refrigerant can be shortened, and the heat loss of the refrigerant (heat inflow from the outside) can be reduced. [Explanation of symbols]

[0046] 1: Rotating shaft, 2: Rotating arm, 3: Test specimen, 4: Refrigerant pump, 5: Rotary joint, 6: Refrigerant piping, 7: Flexible refrigerant pipe, 8: Refrigerant flow path, 9a, 9b: Buckets, 10a, 10b: Swinging shaft, 15: Motor, 60, 62: Refrigerant supply piping, 60a, 62a: Flexible pipe connection, 100: Centrifugal load testing apparatus.

Claims

1. The axis of rotation and A rotating arm that can rotate about the aforementioned axis of rotation, A bucket having a configuration that allows a test specimen to be placed, A motor that rotates the aforementioned rotating shaft, Refrigerant pump and Equipped with a flexible pipe for refrigerant, The aforementioned rotating arm has an upward swing axis, The bucket is rotatable about the swing-up axis, The refrigerant pump is connected to a predetermined refrigerant circulation path including the refrigerant flexible pipe, The rotating arm has a rotating arm-side refrigerant pipe which is part of the predetermined refrigerant circulation path, The bucket has a bucket-side refrigerant piping which is part of the predetermined refrigerant circulation path, The refrigerant piping on the rotating arm side has a flexible pipe connection part on the rotating arm side, The bucket-side refrigerant piping has a bucket-side flexible pipe connection portion, The refrigerant flexible pipe is positioned between the rotating arm side flexible pipe connection and the bucket side flexible pipe connection. The rotating arm side flexible pipe connection is positioned above the bucket side flexible pipe connection. The flexible pipe connection portion on the rotating arm side and the flexible pipe connection portion on the bucket side are arranged so that when the rotating arm is stopped, they face outward in the direction of the rotational radius of the rotating arm. A centrifugal force loading test apparatus is configured such that the refrigerant supplied from the refrigerant pump flows from the flexible pipe connection on the rotating arm side toward the flexible pipe connection on the bucket side.

2. The centrifugal force loading test apparatus according to claim 1, wherein a top plate can be installed on the upper surface of the test specimen.

3. The aforementioned rotating shaft has a rotary joint, The centrifugal force loading test apparatus according to claim 1, wherein the predetermined refrigerant circulation path includes refrigerant piping arranged between the refrigerant pump and the side surface of the rotary joint.

4. The centrifugal force loading test apparatus according to claim 1, wherein the flexible refrigerant tube is curved so as to be convex outward in the direction of the rotational radius of the rotating arm.

5. The centrifugal force loading test apparatus according to claim 1, wherein the flexible tube for the refrigerant is formed of a resin hose or a braided hose having a vacuum double structure.

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