New energy battery tray pressure resistance detection mechanism

Abstract

The invention relates to the technical field of pressure resistance detection, in particular to a new energy battery tray pressure resistance detection mechanism, which comprises a workbench and a pressure detection device, and is characterized in that a plurality of square air bags are arranged at the top of the workbench and surround the outer surface of a tray body; the top of the workbench is provided with a pneumatic conveying mechanism for driving the plurality of square air bags to extrude the tray body, the top of the workbench is provided with ejector rods in contact with four corners of the tray body, and the workbench is provided with a fracture detection mechanism for reading through the ejector rods after the tray body is detected. The square air bag is arranged to be in contact with the tray body, so that the square air bag is directly attached to the outer side of the tray, the air bag is inflated into the square air bag through the pneumatic conveying mechanism, the air bag can be tightly attached to the outer surface of the tray, stress concentration points are effectively eliminated, the accuracy of detection data is guaranteed, and convenience is provided for follow-up analysis or secondary utilization.

Description

Technical Field

[0001] This invention relates to the field of pressure resistance testing technology, specifically to a pressure resistance testing mechanism for a new energy battery tray. Background Technology

[0002] As a key load-bearing component of the power battery system of new energy vehicles, the pressure resistance performance of the new energy battery tray is directly related to the structural safety, driving safety and even personnel safety of the battery system. With the rapid development of the new energy vehicle industry, the requirements for the strength, rigidity and pressure resistance stability of the battery tray are becoming increasingly stringent. As a result, the new energy battery tray pressure resistance testing device has emerged and become the core equipment to ensure the quality of the battery tray.

[0003] The contact area between the fixture and the pallet is mostly a rigid metal plane or a fixed-shape protrusion, which is difficult to adapt to the irregular structure of the pallet surface. This will result in a small contact area and excessive local pressure, which will form stress concentration points. As a result, the deformation and stress state of the pallet during the test will deviate significantly from the actual working conditions, directly affecting the accuracy of the test data.

[0004] Meanwhile, the rigid contact between the rigid clamp and the pallet may cause relative slippage during loading due to insufficient fit, or excessive local pressure may cause wear on the pallet surface coating and deformation of the edges and corners. This is especially true for pallets with high brittleness, such as composite materials and lightweight alloys, which are more prone to non-detectable damage. To address this, we propose a pressure resistance testing mechanism for new energy battery pallets. Summary of the Invention

[0005] One of the technical problems to be solved in this application is: how to design a pressure resistance testing mechanism for new energy battery trays that can protect the trays from excessive local pressure during clamping and prevent damage caused by the clamps.

[0006] To address the aforementioned technical problems, this application provides a pressure resistance testing mechanism for a new energy battery tray, comprising a workbench and a pressure testing device. A tray body is disposed between the workbench and the pressure testing device. Multiple square airbags are disposed on the top of the workbench, surrounding the outer surface of the tray body. A pneumatic conveying mechanism is disposed on the top of the workbench to drive the multiple square airbags to compress the tray body. Top rods that contact the four corners of the tray body are disposed on the top of the workbench. A fracture detection mechanism is disposed on the workbench to take readings through the top rods after the tray body is tested.

[0007] In some embodiments, the pneumatic conveying mechanism includes multiple sealing frames sleeved on the outside of multiple square airbags, each of the multiple sealing frames having a straight tube inside, each of the multiple straight tubes having two hollow plates at its end, a flexible tube between the two hollow plates, and an automatic pneumatic motor mounted on a workbench at the end of one of the hollow plates.

[0008] In some embodiments, a piston disc is movably disposed on the inner wall of the straight tube, a push rod is disposed at the end of the piston disc and passing through the straight tube, and a movable frame is disposed at the end of the push rod and installed inside the square airbag. Multiple through slots are opened on the outer surface of the straight tube, and multiple support members are disposed on the inner side of the movable frame and installed inside the square airbag to support the square airbag.

[0009] In some embodiments, a limiting ring is movably connected to the inner wall of a straight tube and sleeved on the outer side of the push rod, and a spring sleeved on the outer side of the push rod is provided between the inner wall of the straight tube and the limiting ring.

[0010] In some embodiments, the support member includes two mounting plates disposed on the side of the movable frame and inside the square airbag, one of the mounting plates having a sleeve at its end, and the other mounting plate having a straight rod movably connected to the inside of the sleeve on its side.

[0011] In some embodiments, a second spring is provided between the inner wall of the sleeve and the end of the straight rod.

[0012] In some embodiments, the square airbag is composed of an inner bladder layer, a restraint layer, and an outer shell layer, arranged from the inside out.

[0013] In some embodiments, the fracture detection mechanism includes a protective shell on the top of the workbench on which a top rod is movably mounted. A support frame is provided on the inner side of the protective shell, and a spring is provided between the top of the support frame and the bottom of the top rod.

[0014] In some embodiments, a sleeve plate is fitted on the outer side of the top rod, a rack is installed on the side of the sleeve plate, a worm is provided on the inner side of the support frame, and a gear that meshes with the rack is fitted on the outer side of the worm.

[0015] In some embodiments, a vertical plate is provided on the top of the support frame, a concentric shaft penetrating the protective shell is provided on the side of the vertical plate, a worm gear meshing with a worm is sleeved on the outer side of the concentric shaft, and a scale is provided at the end of the concentric shaft on the outer side of the protective shell.

[0016] The present invention has at least the following beneficial effects: 1. By setting a square airbag to contact the tray body, the square airbag is directly attached to the outside of the tray, and gas is injected into the square airbag by a pneumatic conveying mechanism. This allows the airbag to adhere tightly to the outer surface of the tray, adapting to the irregular structure of the outside of the tray. The inflated airbag will evenly transmit pressure, avoiding the problem of excessive local pressure caused by rigid contact, effectively eliminating stress concentration points, thereby ensuring the accuracy of the test data, and also providing convenience for subsequent analysis or secondary use.

[0017] 2. When the square airbag comes into contact with the outside of the tray body, its flexible nature prevents the tray from deforming prematurely due to hard compression. At the same time, the cushioning effect of the airbag can effectively prevent wear on the surface coating of the tray and reduce the impact of corners and edges. Especially for materials with high brittleness, it can significantly reduce the risk of non-inspection damage and ensure the original state of the tray during the inspection process.

[0018] 3. The top rod is set to contact the four corners of the tray body. If the tray breaks during the test, the breakage detection mechanism connected to the top rod will record it, eliminating the need for manual judgment, effectively shortening the processing time after the test is interrupted, and thus improving the overall test efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0020] Figure 2 This is a schematic diagram of the structure of the pallet body, the square airbag, and the pneumatic conveying mechanism of the present invention.

[0021] Figure 3 This is a schematic diagram of the structure of the tray body, sealing frame, and straight tube of the present invention.

[0022] Figure 4 This is a schematic diagram of the explosion structure of the sealing frame, straight tube, and square airbag of the present invention.

[0023] Figure 5 This is an exploded structural diagram of the square airbag, straight tube, push rod, and moving frame of the present invention.

[0024] Figure 6 This is a schematic diagram of the structure of the movable frame and support component of the present invention.

[0025] Figure 7 This is an exploded structural diagram of the support component of the present invention.

[0026] Figure 8 This is a schematic diagram of the top rod, dial, and protective shell of the present invention.

[0027] Figure 9 This is a schematic diagram of the fracture detection mechanism and top rod of the present invention.

[0028] Figure 10 This is a schematic diagram of the structure of the sleeve plate, dial, concentric shaft and worm gear of the present invention.

[0029] In the diagram: 1. Workbench; 2. Pressure detection device; 3. Pallet body; 4. Pneumatic conveying mechanism; 41. Automatic pneumatic motor; 42. Hoses; 43. Hollow plate; 44. Sealing frame; 45. Straight pipe; 46. Through groove; 47. Push rod; 48. Piston disc; 49. Limiting ring; 410. Spring 1; 411. Moving frame; 5. Square airbag; 6. Fracture detection mechanism; 61. Protective shell; 62. Dial; 63. Support frame; 64. Vertical plate; 65. Sleeve plate; 66. Spring 3; 67. Worm gear; 68. Rack; 69. Gear; 610. Worm; 611. Concentric shaft; 7. Support component; 71. Straight rod; 72. Sleeve; 73. Spring 2; 74. Mounting plate; 8. Top rod. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1: Please refer to Figures 1-10 The present invention provides a technical solution: a pressure resistance testing mechanism for a new energy battery tray, comprising a workbench 1 and a pressure testing device 2, a tray body 3 disposed between the workbench 1 and the pressure testing device 2, a plurality of square airbags 5 disposed on the top of the workbench 1, which surround the outer surface of the tray body 3, a pneumatic conveying mechanism 4 disposed on the top of the workbench 1 to drive the plurality of square airbags 5 to squeeze the tray body 3, a top rod 8 disposed on the top of the workbench 1 that contacts the four corners of the tray body 3, and a fracture detection mechanism 6 disposed on the workbench 1 to take readings through the top rods 8 after the tray body 3 is tested.

[0032] The function of the square airbag 5 is to completely fit the outer surface of the pallet body 3: First, it can limit the pallet body 3, and its square structure can increase the limiting area and improve the limiting stability; Second, it can reduce the damage to the pallet body 3 through flexible contact, avoid non-detectable deformation or surface wear, thereby improving the accuracy of the detection results.

[0033] The top rod 8 contacts the four corners of the pallet body 3. When the pallet breaks, the four corners will drop. The severity of the breakage can be deduced from the drop distance. However, the specific location of the breakage still needs to be confirmed by manual observation. This design can provide key reference for subsequent analysis of the material properties and structural rationality of the pallet body 3, and help to improve the material selection and structural design in a targeted manner.

[0034] The pneumatic conveying mechanism 4 includes multiple sealing frames 44 sleeved on the outside of multiple square airbags 5. Each sealing frame 44 has a straight pipe 45 inside. The ends of the multiple straight pipes 45 are provided with two hollow plates 43. A hose 42 is provided between the two hollow plates 43. An automatic pneumatic motor 41 is installed on the workbench 1 at the end of one of the hollow plates 43.

[0035] Air is inflated into the hollow plates 43 by automatic pneumatic motors 41. Each automatic pneumatic motor 41 is responsible for both sides of the pallet body 3, thereby achieving coverage of the four sides of the pallet. Two adjacent hollow plates 43 are connected by hoses 42 to ensure rapid airflow inside and to ensure the synchronicity and uniformity of the inflation process. The connection between the square airbag 5 and the sealing frame 44 adopts a sealing design to effectively prevent gas leakage. The hollow plates 43 are inflated into the square airbag 5 and the sealing frame 44 through straight pipes 45, so that the airbag can expand evenly and fit tightly against the surface of the pallet. Therefore, inflation efficiency is guaranteed, and the sealing measures and gas flow design ensure that the airbag stably wraps around the pallet and applies uniform pressure, providing a reliable basis for subsequent testing.

[0036] A piston disc 48 is movably installed on the inner wall of the straight tube 45. A push rod 47 is installed at the end of the piston disc 48, which passes through the straight tube 45. A movable frame 411 is installed at the end of the push rod 47 and installed inside the square airbag 5. Multiple through slots 46 are opened on the outer surface of the straight tube 45. Multiple support members 7 are installed inside the square airbag 5 on the inner side of the movable frame 411 to support the square airbag 5.

[0037] When gas enters the straight pipe 45, it pushes the piston disc 48 inside the pipe to move. The piston disc 48 synchronously drives the push rod 47 to move, which in turn causes the moving frame 411 to move accordingly, so that the outer square airbag 5 is pre-fitted to the corresponding outer side of the tray body 3, which is a pre-contact for subsequent complete bonding.

[0038] As the piston disc 48 continues to push, when it moves to the position of the through groove 46, the sealing frame 44 is connected to the straight pipe 45 through the through groove 46, allowing gas to smoothly enter the interior of the sealing frame 44. Through the gas-driven linkage structure, the pre-positioned contact between the airbag and the tray is achieved, and the inflation timing of the sealing frame 44 is controlled by the position control of the piston disc 48, providing an orderly action connection for the tight fit between the airbag and the tray, ensuring the stability and accuracy of the fitting process.

[0039] A limiting ring 49 is movably connected to the inner wall of the straight tube 45 on the outer side of the push rod 47, and a spring 410 is provided between the inner wall of the straight tube 45 and the limiting ring 49 and sleeved on the outer side of the push rod 47.

[0040] The spring 410 is deformed when the piston disc 48 presses against the limiting ring 49. When the sealing frame 44, straight pipe 45 and square airbag 5 are filled with gas, the spring 410 will be further compressed. After the square airbag 5 is used, the spring 410 will drive the piston disc 48 to reset when the gas pressure is less than the elastic force of the spring 410. This ensures the stable operation of the inflation process and realizes the automatic reset of the structure, improving the ease of use of the device.

[0041] The bracket 7 includes two mounting plates 74 disposed on the side of the movable frame 411 and inside the square airbag 5. One mounting plate 74 has a sleeve 72 at its end, and the other mounting plate 74 has a straight rod 71 movably connected to the inside of the sleeve 72 on its side.

[0042] A spring 73 is provided between the inner wall of the sleeve 72 and the end of the straight rod 71.

[0043] When the square airbag 5 breaks accidentally, the mounting plate 74 at the end of the straight rod 71 will lose its restraint. At this time, the spring 73, which was originally squeezed inside the sleeve 72 by the straight rod 71, will release its elasticity, pushing the straight rod 71 to move quickly, so that the mounting plate 74 will quickly press against the outside of the tray body 3.

[0044] It can quickly fill the gap when the airbag fails, and maintain the limiting effect on the tray through the tight contact between the mounting plate 74 and the tray, effectively preventing the tray from falling off the worktable 1 due to loss of restraint. In this way, it avoids the risk of personnel injury caused by the tray falling, and also reduces the damage to the equipment caused by accidental collisions, adding a safety guarantee to the testing process and ensuring that the safety and stability of the testing environment can still be maintained in case of emergencies.

[0045] The square airbag 5 is composed of an inner liner, a restraint layer, and an outer shell layer from the inside out. The three-layer structure provides comprehensive safety protection for the square airbag 5. Each layer has a clear division of labor and works together. The inner liner is made of 3mm thick silicone rubber material, and the surface is molded to form a raised texture.

[0046] The middle constraint layer is a Kevlar fiber woven mesh with a mesh size of 10mm×10mm. This high-strength fiber material can limit the radial expansion of the airbag, prevent excessive deformation, and significantly enhance the axial support stiffness to ensure the uniformity of load transfer.

[0047] The outer shell is made of nylon-reinforced material. With its excellent wear resistance, it can effectively resist frictional wear when in contact with the three sides of the tray body, extending the service life of the airbag. The combination of the three-layer structure not only meets the flexible fit requirements of the airbag, but also improves the overall safety and durability through the complementary properties of the materials, providing reliable support for the testing process.

[0048] Example 2: Please refer to Figure 8-10 The present invention provides a technical solution: the fracture detection mechanism 6 includes a protective shell 61 on the top of the workbench 1 on which a top rod 8 is movably mounted, a support frame 63 is provided on the inner side of the protective shell 61, and a spring 66 is provided between the top of the support frame 63 and the bottom of the top rod 8.

[0049] The protective shell 61 can protect the internal components during the crush test. The push rod 8 is movably installed inside the protective shell 61 and can be flexibly raised and lowered in the vertical direction. A support frame 63 is fixed inside the protective shell 61. A spring 66 is connected between the top of the support frame 63 and the bottom of the push rod 8. The spring 66 is always in a pre-compressed state, providing a continuous upward thrust to the push rod 8 and ensuring that the top of the push rod 8 stably abuts against the four corners of the tray body 3.

[0050] A sleeve plate 65 is fitted on the outer side of the push rod 8, and a rack 68 is installed on the side of the sleeve plate 65. A worm gear 610 is provided on the inner side of the support frame 63, and a gear 69 that meshes with the rack 68 is fitted on the outer side of the worm gear 610.

[0051] When the tray breaks, causing the push rod 8 to move downwards, the sleeve plate 65 descends synchronously with the push rod 8. The rack 68 then drives the gear 69 to rotate, which in turn drives the worm gear 610 to rotate. This mechanical linkage converts the vertical displacement of the push rod 8 into the rotational motion of the worm gear 610. The descent distance of the push rod 8 can be quantified by the rotation angle of the worm gear 610, improving the accuracy of fracture detection. At the same time, the meshing between the worm gear 610 and the gear 69 has a self-locking characteristic, which can maintain the stability of the position after the push rod 8 is displaced, avoiding measurement errors caused by vibration and other factors.

[0052] The top of the support frame 63 is provided with a vertical plate 64, and the side of the vertical plate 64 is provided with a concentric shaft 611 that penetrates the protective shell 61. The outer side of the concentric shaft 611 is fitted with a worm wheel 67 that meshes with the worm 610. The end of the concentric shaft 611 on the outer side of the protective shell 61 is provided with a dial 62.

[0053] A scale 62 is installed on the end of the concentric shaft 611 that extends outward from the protective shell 61. The edge of the scale 62 is marked with fine graduations, and a pointer is provided at the corresponding position on the outer wall of the protective shell 61 as a reference. This design converts the vertical displacement of the top rod 8 into the rotation angle of the scale 62 after being transmitted by the worm gear 610 and the worm wheel 67. By reading the rotation value of the scale 62, the descent distance of the four corners of the tray can be quantified intuitively.

[0054] Because the worm gear 67 and worm 610 transmission have speed reduction and torque amplification characteristics, even a small displacement of the push rod 8 can produce a significant angular change on the scale 62, greatly improving the measurement accuracy and providing a visual quantitative basis for judging the degree of tray breakage.

[0055] Working principle: When using this device, first place the tray body 3 on the workbench 1. Then, by starting the automatic pneumatic motor 41, gas will be delivered to the hollow plate 43 and the hose 42, so that the two hollow plates 43 are filled with gas. At this time, the gas enters the straight pipe 45 through the hollow plate 43. The gas in the straight pipe 45 will move through the piston disc 48, which will push the push rod 47 to move. At this time, the piston disc 48 will be pushed to the through groove 46, so that the inside of the sealing frame 44 is connected to the through groove 46 and the straight pipe 45. With pipe 45 connected, push rod 47 will push moving frame 411 to move via piston disc 48. Moving frame 411 will push multiple support pieces 7 so that square airbag 5 is pre-fitted to the outside of tray body 3. At this time, gas enters the sealing frame 44 and then enters the square airbag 5, so that square airbag 5 is completely fitted to the outside of tray body 3. Automatic pneumatic motor 41 will stop working, and the gas inside square airbag 5 will not be discharged. At this time, piston disc 48 will also push limit ring 49 to squeeze spring 410.

[0056] When the square airbag 5 breaks accidentally, the mounting plate 74 at the end of the straight rod 71 loses its restraint, and the spring 73 is squeezed by the straight rod 71 inside the sleeve 72. Therefore, under the action of the spring 73, the straight rod 71 will quickly press the mounting plate 74 against the outside of the tray body 3 to prevent the tray body 3 from losing its limit and falling off the worktable 1, and further prevent personnel injury or equipment damage.

[0057] When the tray body 3 is placed on the workbench 1, the four corners of the tray body 3 will contact the push rod 8. When the tray body 3 breaks, the push rod 8 will descend to compress the spring 66 and also drive the sleeve plate 65 to move. The sleeve plate 65 will drive the rack 68 to descend, the rack 68 will drive the gear 69 to rotate, the gear 69 will drive the internal worm 610 to rotate, the worm 610 will drive the worm wheel 67 to rotate, and the worm wheel 67 will drive the concentric shaft 611 to rotate. Therefore, the condition of the tray body 3 breaking can be obtained by the scale on the dial 62.

[0058] After completion, the gas inside the square airbag 5 will be sucked out by the automatic pneumatic motor 41. At this time, the piston disc 48 will not completely block the through groove 46. When the pressure of the square airbag 5 and the sealing frame 44 is less than the pressure of the spring 410 on the limiting ring 49, the piston disc 48 will block the through groove 46, so that the piston disc 48 and the square airbag 5 will be reset. Finally, the tray body 3 can be taken out.

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A pressure resistance testing mechanism for a new energy battery tray, comprising a workbench (1) and a pressure testing device (2), wherein a tray body (3) is disposed between the workbench (1) and the pressure testing device (2), characterized in that: The top of the workbench (1) is provided with multiple square airbags (5), which surround the outer surface of the pallet body (3). The top of the workbench (1) is provided with a pneumatic conveying mechanism (4) that drives the multiple square airbags (5) to squeeze the pallet body (3). The top of the workbench (1) is provided with a top rod (8) that contacts the four corners of the pallet body (3). The workbench (1) is provided with a fracture detection mechanism (6) that reads the value of the pallet body (3) by the top rod (8) after detection.

2. The new energy battery tray pressure resistance testing mechanism according to claim 1, characterized in that: The pneumatic conveying mechanism (4) includes multiple sealing frames (44) sleeved on the outside of multiple square airbags (5). Each of the multiple sealing frames (44) is provided with a straight tube (45). The ends of the multiple straight tubes (45) are provided with two hollow plates (43). A hose (42) is provided between the two hollow plates (43). An automatic pneumatic motor (41) installed on the workbench (1) is provided at the end of one of the hollow plates (43).

3. The new energy battery tray pressure resistance testing mechanism according to claim 2, characterized in that: A piston disc (48) is movably provided on the inner wall of the straight tube (45). A push rod (47) is provided at the end of the piston disc (48) and passes through the straight tube (45). A movable frame (411) is provided at the end of the push rod (47) and installed inside the square airbag (5). Multiple through grooves (46) are provided on the outer surface of the straight tube (45). Multiple support members (7) installed inside the square airbag (5) are provided on the inner side of the movable frame (411) to support the square airbag (5).

4. The new energy battery tray pressure resistance testing mechanism according to claim 3, characterized in that: The push rod (47) is fitted with a limiting ring (49) that is movably connected to the inner wall of the straight tube (45). A spring (410) is fitted on the outside of the push rod (47) between the inner wall of the straight tube (45) and the limiting ring (49).

5. The new energy battery tray pressure resistance testing mechanism according to claim 3, characterized in that: The bracket (7) includes two mounting plates (74) disposed on the side of the movable frame (411) and inside the square airbag (5). One of the mounting plates (74) has a sleeve (72) at its end, and the other mounting plate (74) has a straight rod (71) movably connected to the inside of the sleeve (72) on its side.

6. The new energy battery tray pressure resistance testing mechanism according to claim 5, characterized in that: A second spring (73) is provided between the inner wall of the sleeve (72) and the end of the straight rod (71).

7. The new energy battery tray pressure resistance testing mechanism according to claim 1, characterized in that: The square airbag (5) is composed of an inner bladder layer, a restraint layer, and an outer shell layer, arranged from the inside out.

8. The new energy battery tray pressure resistance testing mechanism according to claim 1, characterized in that: The fracture detection mechanism (6) includes a protective shell (61) on the top of the workbench (1) on which a top rod (8) is movably mounted. A support frame (63) is provided on the inner side of the protective shell (61), and a spring (66) is provided between the top of the support frame (63) and the bottom of the top rod (8).

9. The new energy battery tray pressure resistance testing mechanism according to claim 8, characterized in that: The top rod (8) is fitted with a sleeve plate (65) on its outer side, and a rack (68) is installed on the side of the sleeve plate (65). The support frame (63) is provided with a worm gear (610) on its inner side, and a gear (69) that meshes with the rack (68) is fitted on the outer side of the worm gear (610).

10. The new energy battery tray pressure resistance testing mechanism according to claim 9, characterized in that: The support frame (63) is provided with a vertical plate (64) at the top, and a concentric shaft (611) penetrating the protective shell (61) is provided on the side of the vertical plate (64). A worm wheel (67) that meshes with the worm (610) is sleeved on the outside of the concentric shaft (611), and a dial (62) is provided at the end of the concentric shaft (611) on the outside of the protective shell (61).

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