A lightning arrester for power system

Abstract

The present invention discloses an electric power system arrester, comprising an upper mounting plate and a lower mounting plate, a housing being installed between the upper mounting plate and the lower mounting plate, and a pressure triggering assembly being arranged on the upper mounting plate so as to operate a switching mechanism arranged inside the lower mounting plate, and the present invention relates to the technical field of electric power systems. The electric power system arrester is provided with a switching mechanism, and utilizes the pressure of the arrester after receiving an electric power wave, so that the pressure triggering assembly drives the control unit to perform a switching operation of a variable resistor, and while completing the switching instantaneously, maintains the stability of the variable resistor after switching, thereby avoiding the problem of subsequent damage to the arrester and equipment caused by continuous attacks of the electric power wave, and at the same time improving the application safety of the electric power system arrester, and reducing the damage rate of the equipment while realizing the maintenance operation of the maintenance personnel before the next electric power wave event occurs.

Description

Technical Field

[0001] The invention relates to the technical field of power systems, and in particular to a lightning arrester for a power system. Background Art

[0002] The reference patent name is: A lightning arrester for a new energy power system (patent publication number: CN116153601A, patent publication date: 2023-05-23), including a lightning arrester core, which is composed of multiple resistors and metal gaskets, each resistor is arranged axially, and a metal gasket is arranged between any two adjacent resistors. The composite jacket is arranged on the outside of the lightning arrester core and is connected to the lightning arrester core through an insulating fixing sheet and a fixing member. The insulating fixing sheet is connected to the metal gasket between the two resistors. The metal gasket not connected to the insulating fixing sheet is the first metal gasket, and the metal gasket connected to the insulating fixing sheet includes at least a second metal gasket. The diameter of the second metal gasket is smaller than the diameter of the first metal gasket. The insulating fixing sheet is sleeved and fixed on the second metal gasket. In the lightning arrester for a new energy power system, the insulating fixing sheet can conduct the heat generated by the lightning arrester core to the composite jacket, thereby improving the heat dissipation efficiency, effectively improving the temperature distribution and thermal characteristics of the lightning arrester core, and enhancing the tolerance characteristics of the lightning arrester.

[0003] Based on the description in the above-mentioned documents, when existing power system lightning arresters experience lightning weather, the electric power waves accidentally transmitted to the lightning arresters vary in size, causing instantaneous changes in the variable resistors in the lightning arresters. When encountering continuous attacks from electric power waves, the variable resistors often fail to complete the buffering operation in time, resulting in subsequent damage to the lightning arresters and equipment, and the inability to complete maintenance operations in time. Therefore, the present invention provides a power system lightning arrester. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a lightning arrester for an electric power system, which solves the problem that during the process of the existing lightning arrester for an electric power system experiencing lightning weather, the electric power waves vary in size, causing instantaneous changes in the variable resistor in the lightning arrester, and often when encountering continuous attacks of the electric power waves, the variable resistor often fails to complete the buffering operation in time, resulting in subsequent damage to the lightning arrester and equipment.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A lightning arrester for a power system, comprising an upper mounting plate and a lower mounting plate, a housing is installed between the upper mounting plate and the lower mounting plate, and a pressure trigger component is provided on the upper mounting plate to operate a switching mechanism provided inside the lower mounting plate, the switching mechanism comprising:

[0006] The control part includes an electrical column rotatably mounted at the bottom center of the inner cavity of the lower mounting plate, a ratchet is mounted on the surface of the electrical column through drainage columns equidistantly arranged in a circumferential shape, and a control ratchet is connected to the inner cavity of the lower mounting plate through an elastic component, and the control ratchet contacts the surface of the ratchet and limits the rotation of the ratchet when no movement occurs, and a connecting column is mounted on the top of the control ratchet, and a trapezoidal block is mounted through the connecting column;

[0007] The variable resistor is provided in plurality and is equidistantly mounted on the top of the ratchet wheel in a circumferential shape through a supporting column, and a contact assembly is provided on the top of the variable resistor.

[0008] Preferably, the pressure trigger component comprises:

[0009] An external pipe is installed on the top of the inner cavity of the upper mounting plate;

[0010] The contact slides on the inner wall of the external tube, and a pressure spring is installed between the opposite sides of the external tube and the contact, and a linkage assembly is provided on the surface of the contact to contact the trapezoidal block;

[0011] The support tube is installed inside the shell, and the contact moves downward after receiving the electric wave to contact with the support tube to realize the transmission of the electric wave. The bottom of the support tube is installed with an upper contact piece.

[0012] Preferably, the linkage assembly comprises a linkage ring fixedly mounted on the contact surface, a linkage rod is mounted on the surface of the linkage ring, and a linkage block is rotatably mounted on the bottom end of the linkage rod, and the inclined surface of the linkage block is always in contact with the inclined surface of the trapezoidal block.

[0013] Preferably, the elastic component comprises:

[0014] A sliding block is fixedly mounted on the bottom of the control ratchet, a control groove is provided at the bottom of the lower mounting plate and directly below the sliding block, and the sliding block slides inside the control groove, and an arc spring is installed between the sliding block and the opposite sides of the control groove;

[0015] The reset assembly is arranged on the outer side of the control ratchet away from the ratchet wheel and is used to keep the control ratchet wheel always in contact with the ratchet wheel.

[0016] Preferably, the reset assembly includes a reset spring fixedly mounted on the outer surface of the control ratchet away from the ratchet wheel, and an arc block is installed on the inner wall of the lower mounting plate and in the direction of movement of the reset spring, and the extended end of the reset spring contacts the surface of the arc block to realize the actuation operation of the control ratchet.

[0017] Preferably, the inclined surfaces of the linkage block and the trapezoidal block are opposite to each other, and the inclined surfaces of the linkage block and the trapezoidal block always keep in contact. In the process of the linkage block moving downward, the sliding block below the trapezoidal block is driven to slide inside the control groove and press the arc spring to contract, thereby controlling the movement of the ratchet teeth to drive the ratchet wheel to rotate.

[0018] Preferably, the contact assembly comprises:

[0019] A concave frame is fixedly mounted at the cross section of the top of the variable resistor, and a twisting assembly is arranged inside the concave frame to make the lower contact piece rotate and the lower contact piece contacts the side of the upper contact piece;

[0020] The limit plate is located in the clockwise direction of the lower contact piece and is installed on the concave frame, and the surface of the limit plate contacts the clockwise side of the lower contact piece. The limit plate is used to limit the lower contact piece from rotating toward the clockwise side.

[0021] Preferably, the torsion assembly includes a rotating column that passes through the lower contact piece and is fixed to the lower contact piece, and the two ends of the rotating column are rotatably connected to the side of the concave frame, and a torsion spring is sleeved on the surface of the rotating column, and the two ends of the torsion spring are fixed to the opposite sides of the lower contact piece and the concave frame.

[0022] Beneficial Effects

[0023] The present invention provides a lightning arrester for a power system. Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The power system arrester is provided with a switching mechanism, which utilizes the pressure of the arrester after being subjected to an electric wave, so that the pressure trigger component drives the control unit to perform a switching operation of the variable resistor, and while completing the switching instantaneously, maintains the stability of the variable resistor after switching, thereby avoiding the problem of subsequent damage to the arrester and equipment caused by continuous attacks of electric waves, while improving the application safety of the power system arrester, reducing the damage rate of equipment, and enabling maintenance personnel to perform maintenance operations before the next electric wave event occurs.

[0025] (2) The power system lightning arrester is provided with a pressure trigger component, so that when it is subjected to power waves, it can not only eliminate the power waves, but also synchronously switch the variable resistors that process the power waves, thereby improving the efficiency of the lightning arrester. There is no need for personnel to perform switching operations, thus ensuring the safety of the lightning arrester. It can also be used to prevent equipment from being attacked by multiple power waves, and can also spread the number of times the variable resistors have to withstand the attacks, thereby extending the use time.

[0026] (3) The power system lightning arrester is provided with an elastic component. After the control ratchet drives the ratchet wheel to rotate and switch, the initial state of the control ratchet is restored under the reset property of the arc spring, and the control ratchet and the ratchet wheel are always kept in contact under the reset property of the reset spring. The initial state of the lightning arrester is restored under the reset property of the pressure spring, thereby completing the switching and instantaneously completing the preparation operation for the next prevention, and giving time for the previous variable resistor buffer to recover, so that the use of the lightning arrester conforms to real-time automatic operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is an external three-dimensional structural diagram of the present invention;

[0028] Figure 2 It is a cross-sectional view of the internal three-dimensional structure of the present invention;

[0029] Figure 3 It is the internal three-dimensional structure diagram of the present invention;

[0030] Figure 4 It is a three-dimensional structural diagram of the pressure triggering assembly of the present invention;

[0031] Figure 5 It is a three-dimensional structural diagram of the switching mechanism of the present invention;

[0032] Figure 6 It is a three-dimensional structural exploded diagram of the contact assembly of the present invention;

[0033] Figure 7 For the present invention Figure 6 A magnified view of the local structure at center A;

[0034] Figure 8 This is a three-dimensional internal structure diagram of the lower mounting plate of the present invention;

[0035] Fig. 9 The figure is a three-dimensional structural exploded view of the reset assembly of the present invention;

[0036] Fig.10 It is a three-dimensional structural diagram of the linkage assembly of the present invention;

[0037] Fig.11 It is a three-dimensional structural exploded view of the elastic component of the present invention.

[0038] In the figure:

[0039] 1-Upper mounting plate;

[0040] 2-Lower mounting plate;

[0041] 3- Shell;

[0042] 4-pressure trigger assembly, 41-external pipe, 42-contact, 43-pressure spring, 44-linkage assembly, 441-linkage ring, 442-linkage rod, 443-linkage block, 45-support tube, 46-upper contact piece;

[0043] 5-control part, 51-electrical column, 52-drainage column, 53-ratchet, 54-control ratchet, 55-connecting column, 56-trapezoidal block;

[0044] 6- variable resistor;

[0045] 7-elastic component, 71-sliding block, 72-control groove, 73-arc spring, 74-reset component, 741-reset spring, 742-arc block;

[0046] 8-contact assembly, 81-concave frame, 82-torsion assembly, 821-rotation column, 822-torsion spring, 83-lower contact piece, 84-limiting plate;

[0047] 9-Support column. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] See also Figure 1-Figure 11 , the present invention provides a technical solution:

[0050] A lightning arrester for a power system includes an upper mounting plate 1 and a lower mounting plate 2, a housing 3 is installed between the upper mounting plate 1 and the lower mounting plate 2, and a pressure trigger component 4 is provided on the upper mounting plate 1 to operate a switching mechanism provided inside the lower mounting plate 2, the switching mechanism including:

[0051] The control part 5 includes an electrical column 51 rotatably mounted at the bottom center of the inner cavity of the lower mounting plate 2, a ratchet 53 is mounted on the surface of the electrical column 51 through drainage columns 52 equidistantly arranged in a circumferential shape, and a control ratchet 54 is connected to the inner cavity of the lower mounting plate 2 through an elastic component 7, and the control ratchet 54 contacts the surface of the ratchet 53 and limits the rotation of the ratchet 53 when no movement occurs, and a connecting column 55 is mounted on the top of the control ratchet 54, and a trapezoidal block 56 is mounted through the connecting column 55;

[0052] The variable resistor 6 is provided in plurality and is equidistantly mounted on the top of the ratchet 53 in a circular shape through a support column 9 , and a contact assembly 8 is provided on the top of the variable resistor 6 .

[0053] Among them, other basic structures of the power system lightning arrester are not explained, and they are existing mature technologies that can complete the operation of lightning protection in conjunction with the structure of this application. At the same time, the materials of the specific structure are produced according to needs.

[0054] By providing a switching mechanism, the pressure on the arrester after being subjected to an electric wave is utilized, so that the pressure trigger component 4 drives the control unit 5 to perform a switching operation on the variable resistor 6, and while the switching is completed instantaneously, the stability of the variable resistor 6 after the switching is maintained, thereby avoiding the problem of subsequent damage to the arrester and equipment caused by continuous attacks of electric waves, while improving the application safety of the arrester of the power system, reducing the damage rate of equipment, and enabling maintenance personnel to perform maintenance operations before the next electric wave event occurs.

[0055] See also Figure 2-Figure 4 In the embodiment of the present invention, the pressure trigger component 4 includes:

[0056] The external pipe 41 is installed on the top of the inner cavity of the upper mounting plate 1;

[0057] The contact 42 slides on the inner wall of the external tube 41, and a pressure spring 43 is installed between the opposite sides of the external tube 41 and the contact 42, and a linkage assembly 44 is provided on the surface of the contact 42 to contact the trapezoidal block 56;

[0058] The support tube 45 is installed inside the housing 3 , and the contact 42 moves downward after receiving the electric wave to contact the support tube 45 to realize the electric wave transmission. An upper contact piece 46 is installed at the bottom of the support tube 45 .

[0059] See also Figure 3-Figure 4 In the embodiment of the present invention, the linkage assembly 44 includes a linkage ring 441 fixedly mounted on the surface of the contact 42, and a linkage rod 442 is mounted on the surface of the linkage ring 441, and a linkage block 443 is rotatably mounted on the bottom end of the linkage rod 442, and the inclined surface of the linkage block 443 always keeps in contact with the inclined surface of the trapezoidal block 56.

[0060] By providing a pressure trigger component 4, when subjected to electric waves, not only can the electric wave elimination operation be achieved, but also the variable resistor for processing the electric wave can be switched synchronously and linked, thereby improving the efficiency of the use of the lightning arrester, and eliminating the need for personnel to perform switching operations, thereby ensuring the safety of the use of the lightning arrester. It can also be used to prevent the equipment from being attacked by multiple electric waves, and can also spread the number of times the variable resistor has to withstand the attacks, thereby extending the use time.

[0061] See also Figure 9-11 In the embodiment of the present invention, the elastic component 7 includes:

[0062] The sliding block 71 is fixedly mounted at the bottom of the control ratchet 54. A control groove 72 is provided at the bottom of the lower mounting plate 2 and directly below the sliding block 71. The sliding block 71 slides inside the control groove 72. The sliding block 71 slides in the control groove 72 without generating a vertical movement operation, and the movement of the control ratchet 54 is kept on the same plane. An arc spring 73 is installed between the sliding block 71 and the opposite sides of the control groove 72.

[0063] The reset assembly 74 is disposed on the outer side of the control ratchet 54 away from the ratchet 53 and is used to keep the control ratchet 54 always in contact with the ratchet 53 .

[0064] See also Fig. 9 In the embodiment of the present invention, the reset assembly 74 includes a reset spring 741 fixedly mounted on the outer surface of the control ratchet 54 away from the ratchet wheel 53, and an arc block 742 is installed on the inner wall of the lower mounting plate 2 and in the direction of movement of the reset spring 741, and the extended end of the reset spring 741 contacts the surface of the arc block 742 to realize the actuation operation of the control ratchet 54.

[0065] In the embodiment of the present invention, the inclined surfaces of the linkage block 443 and the trapezoidal block 56 are opposite to each other, and the inclined surfaces of the linkage block 443 and the trapezoidal block 56 always keep in contact. During the downward movement of the linkage block 443, the sliding block 71 below the trapezoidal block 56 is driven to slide inside the control groove 72 and press the arc spring 73 to contract, thereby controlling the movement of the ratchet 54 and driving the ratchet wheel 53 to rotate.

[0066] By providing an elastic component 7, after the control ratchet 54 drives the ratchet 53 to rotate and switch, the initial state of the control ratchet 54 is restored under the reset property of the arc spring 73, and the control ratchet 54 and the ratchet 53 are always kept in contact under the reset property of the reset spring 741, and the initial state of the lightning arrester is restored under the reset property of the pressure spring 43, so that the switching is completed and the preparation operation for the next prevention is completed instantly, and the buffer recovery time of the last variable resistor 6 is given, so that the use of the lightning arrester conforms to real-time automatic operation.

[0067] See also Figure 5-Figure 7 In the embodiment of the present invention, the contact component 8 includes:

[0068] The concave frame 81 is fixedly mounted at the cross section of the top of the variable resistor 6, and a twisting assembly 82 is arranged inside the concave frame 81 to make the lower contact piece 83 rotate, and the lower contact piece 83 contacts the side of the upper contact piece 46;

[0069] The limit plate 84 is located in the clockwise direction of the lower contact piece 83 and is installed on the concave frame 81, and the surface of the limit plate 84 contacts the clockwise side of the lower contact piece 83. The limit plate 84 is used to limit the lower contact piece 83 from rotating clockwise, but can rotate counterclockwise when external force is applied.

[0070] See also Figure 7 In the embodiment of the present invention, the torsion assembly 82 includes a rotating column 821 that passes through the lower contact piece 83 and is fixed to the lower contact piece 83, and the two ends of the rotating column 821 are rotatably connected to the side of the concave frame 81, and a torsion spring 822 is sleeved on the surface of the rotating column 821, and the two ends of the torsion spring 822 are fixed to the opposite sides of the lower contact piece 83 and the concave frame 81.

[0071] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0072] When working, first, after the power system is struck by lightning, it will transmit the power wave to the equipment end. At this time, the lightning arrester connected in parallel to the equipment end will receive the power wave in advance.

[0073] At this time, after the electric wave contacts, the contact 42 and the pressure spring 43 will produce stress changes due to the change in the electric power situation, so that the pressure spring 43 is extended after the pressure is generated, so that the contact 42 and the electrical end of the support tube 45 are in close contact to maintain the stability of the transmission, and the transmission of the electric wave is completed;

[0074] At this time, the downward movement of the contact 42 causes the linkage ring 441, the linkage rod 442 and the linkage block 443 to move synchronously, and causes the inclined surface of the linkage block 443 to abut against the inclined surface of the trapezoidal block 56, so that the trapezoidal block 56 moves, and the trapezoidal block 56 drives the sliding block 71 to slide inside the control groove 72, and compresses the contraction of the arc spring 73, and at the same time drives the control ratchet 54 to move and drives the ratchet 53 to rotate around the electrical column 51;

[0075] The rotation of the ratchet 53 drives the variable resistor 6 on the support column 9 to rotate. At this time, the lower contact piece 83 at the top of the variable resistor 6 contacts the upper contact piece 46 at the bottom of the support tube 45, so that the lower contact piece 83 rotates around the rotating column 821 and passes over the upper contact piece 46, so that the next lower contact piece 83 contacts the upper contact piece 46, thereby realizing the transmission of the electric wave to the variable resistor to achieve the operation of eliminating and grounding;

[0076] After the processing is completed, the arc spring 73 resets the ratchet 54 to its initial state, the reset spring 741 resets the ratchet 54 and the ratchet wheel 53 to always maintain contact, and the pressure spring 43 resets the arrester to its initial state, thereby completing the switching and instantly completing the preparation operation for the next prevention.

[0077] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0078] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A lightning arrester for a power system, comprising an upper mounting plate (1) and a lower mounting plate (2), wherein a housing (3) is mounted between the upper mounting plate (1) and the lower mounting plate (2), and characterized in that: A pressure trigger assembly (4) is provided on the upper mounting plate (1) to operate a switching mechanism provided inside the lower mounting plate (2), wherein the switching mechanism comprises: The control part (5) comprises an electrical column (51) rotatably mounted at the center of the bottom of the inner cavity of the lower mounting plate (2), a ratchet (53) being mounted on the surface of the electrical column (51) via drainage columns (52) equidistantly arranged in a circumferential shape, and a control ratchet (54) being connected to the inner cavity of the lower mounting plate (2) via an elastic component (7), and the control ratchet (54) is in contact with the surface of the ratchet (53) and restricts the rotation of the ratchet (53) when no movement occurs, and a connecting column (55) is mounted on the top of the control ratchet (54), and a trapezoidal block (56) is mounted via the connecting column (55); A plurality of variable resistors (6) are provided and are equidistantly mounted on the top of the ratchet wheel (53) in a circular shape via support columns (9), and a contact assembly (8) is provided on the top of the variable resistor (6); The pressure trigger component (4) comprises: An external pipe (41) mounted on the top of the inner cavity of the upper mounting plate (1); The contact (42) slides on the inner wall of the external tube (41), and a pressure spring (43) is installed between the opposite sides of the external tube (41) and the contact (42), and a linkage assembly (44) is provided on the surface of the contact (42) to contact the trapezoidal block (56); The support tube (45) is installed inside the housing (3), and the contact (42) moves downward after receiving the electric wave to contact the support tube (45) to achieve electric wave transmission. An upper contact piece (46) is installed at the bottom of the support tube (45).

2. A lightning arrester for a power system according to claim 1, characterized in that: The linkage assembly (44) comprises a linkage ring (441) fixedly mounted on the surface of the contact (42), a linkage rod (442) being mounted on the surface of the linkage ring (441), and a linkage block (443) being rotatably mounted on the bottom end of the linkage rod (442), the inclined surface of the linkage block (443) always being in contact with the inclined surface of the trapezoidal block (56).

3. A lightning arrester for a power system according to claim 2, characterized in that: The elastic component (7) comprises: A sliding block (71) is fixedly mounted on the bottom of the control ratchet (54); a control groove (72) is provided at the bottom of the lower mounting plate (2) and directly below the sliding block (71); the sliding block (71) slides inside the control groove (72); and an arc spring (73) is installed between the sliding block (71) and the opposite sides of the control groove (72); The reset assembly (74) is arranged on the outer side of the control ratchet (54) away from the ratchet wheel (53), and is used to keep the control ratchet (54) always in contact with the ratchet wheel (53).

4. A lightning arrester for a power system according to claim 3, characterized in that: The reset assembly (74) comprises a reset spring (741) fixedly mounted on the outer side of the control ratchet (54) away from the ratchet wheel (53), and an arc block (742) is mounted on the inner wall of the lower mounting plate (2) and in the direction of movement of the reset spring (741), and the extended end of the reset spring (741) contacts the surface of the arc block (742) to achieve actuation of the control ratchet (54).

5. The power system arrester according to claim 3, characterized in that: The inclined surfaces of the linkage block (443) and the trapezoidal block (56) are opposite to each other, and the inclined surfaces of the linkage block (443) and the trapezoidal block (56) are always in contact with each other. When the linkage block (443) moves downward, it drives the sliding block (71) below the trapezoidal block (56) to slide inside the control groove (72) and press the arc spring (73) to contract, thereby controlling the movement of the ratchet (54) and driving the ratchet wheel (53) to rotate.

6. The power system lightning arrester according to claim 1, characterized in that: The contact assembly (8) comprises: A concave frame (81) is fixedly mounted at the cross section of the top of the variable resistor (6), and a twisting assembly (82) is arranged inside the concave frame (81) to enable the lower contact piece (83) to rotate, and the lower contact piece (83) contacts the side surface of the upper contact piece (46); The limiting plate (84) is located in the clockwise direction of the lower contact piece (83) and is mounted on the concave frame (81), and the surface of the limiting plate (84) contacts the clockwise side surface of the lower contact piece (83). The limiting plate (84) is used to limit the lower contact piece (83) from rotating in the clockwise direction.

7. A lightning arrester for a power system according to claim 6, characterized in that: The torsion assembly (82) comprises a rotating column (821) that penetrates the lower contact sheet (83) and is fixed to the lower contact sheet (83), and the two ends of the rotating column (821) are rotatably connected to the side surfaces of the concave frame (81), and a torsion spring (822) is sleeved on the surface of the rotating column (821), and the two ends of the torsion spring (822) are fixed to the opposite sides of the lower contact sheet (83) and the concave frame (81).

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