Ultrasonic flowmeter

Abstract

An ultrasonic flowmeter 1 according to an embodiment measures the flow rate of a fluid flowing through piping by a propagation time difference system, and is provided with: two transceivers 4 that transmit or receive ultrasonic waves; a guide member 5 extending in the extension direction of the piping and guiding the two transceivers 4 in the extension direction of the piping; and a pressing member 3 extending in the extension direction of the guide member 5, the pressing member 3 pressing the two transceivers 4 to the piping when the ultrasonic flowmeter 1 is fixed to the piping by winding of two bands individually corresponding to respective end parts of the pressing member 3 around the piping and winding of the bands onto the piping.

Description

ultrasonic flow meter

[0001] The present invention relates to a clamp-on type ultrasonic flowmeter.

[0002] Conventionally, as an ultrasonic flow meter that uses ultrasonic waves to measure the flow rate of a fluid, a clamp-on type is known in which a transmitter / receiver that transmits and receives ultrasonic waves is attached to the outside of the pipe through which the fluid flows. Another type of ultrasonic flow meter is known in which the transmitter / receiver is fixed to the pipe by wrapping a band, also called a belt, around the pipe.

[0003] One known technology related to this type of ultrasonic flowmeter is an ultrasonic flow measuring device in which the size and shape of the wedge-shaped gap formed by the belt passed through a belt hole and wound around a pipe, the pipe, and the guide frame can be adjusted so that an unstrained wedge-shaped leaf spring can be inserted into the gap with the tip of the wedge facing the contact point between the belt and the pipe, and the leaf spring inserted into the gap is distorted by moving it toward the contact point between the belt and the pipe, generating tension in the belt corresponding to the distortion and obtaining a predetermined tightening force (see Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2005-30897

[0005] An object of the present invention is to provide a technique that allows a transmitter / receiver to be fixed to a pipe by a band in a manner that is more suitable for measuring flow rates.

[0006] In order to solve the above-mentioned problems, the ultrasonic flowmeter of this embodiment is an ultrasonic flowmeter that measures the flow rate of a fluid flowing through a pipe using a transit time difference method, and includes two transmitters / receivers that transmit or receive ultrasonic waves, a guide member that extends in the extension direction of the pipe and guides the two transmitters / receivers in the extension direction of the pipe, and a pressing member that extends in the extension direction of the guide member, and when the ultrasonic flowmeter is fixed to the pipe by wrapping two bands that individually correspond to one side and the other side of the pressing member around one side and the other side of the pressing member and wrapping them around the pipe, the pressing member presses the two transmitters / receivers against the pipe.

[0007] According to the present invention, the transmitter / receiver can be fixed to the piping by a band so as to be more suitable for measuring the flow rate.

[0008] 1 is a perspective view showing the configuration of an ultrasonic flowmeter according to an embodiment; FIG. 2 is a side view showing the configuration of an ultrasonic flowmeter according to an embodiment; FIG. 3 is an exploded perspective view showing the configuration of an ultrasonic flowmeter according to an embodiment; FIG. 4 is an exploded perspective view showing the internal configuration of an ultrasonic flowmeter according to an embodiment; FIG. 5 is a cross-sectional view showing the internal configuration of an ultrasonic flowmeter according to an embodiment; FIG. 6 is a perspective view showing the configuration of a transceiver; FIG. 7 is a cross-sectional view showing a transceiver in an unlocked state; FIG. 8 is a cross-sectional view showing a transceiver in an engaged state; FIG. 9 is a cross-sectional view showing a transceiver in a non-contact state; FIG. 10 is a cross-sectional view showing a transceiver in a contact state; FIG. 11 is a schematic side view showing strain generated in an acoustic coupling member of a transceiver due to surface contact; FIG. 12 is a schematic side view showing strain generated in an acoustic coupling member of a transceiver due to point contact; FIG. 13 is a cross-sectional view showing a movable contact member pressed against a pipe with a small diameter; FIG. 14 is a cross-sectional view showing a movable contact member pressed against a pipe with a large diameter.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the direction in which a pipe extends is referred to as the front-rear direction, a direction perpendicular to the front-rear direction is referred to as the up-down direction, and a direction perpendicular to the front-rear direction and the up-down direction is referred to as the lateral direction. In the up-down direction, the side toward which a display unit of an ultrasonic flowmeter attached to a pipe faces is referred to as the upper side.

[0010] (Overall Configuration of Ultrasonic Flowmeter) The configuration of the ultrasonic flowmeter according to this embodiment will be described. Figures 1, 2, and 3 are a perspective view, a side view, and an exploded perspective view, respectively, showing the configuration of the ultrasonic flowmeter according to this embodiment. Figures 4 and 5 are an exploded perspective view and a cross-sectional view, respectively, showing the internal configuration of the ultrasonic flowmeter according to this embodiment. Note that Figure 5 shows the ultrasonic flowmeter and piping cut along a plane that extends in the front-rear and up-down directions and passes through approximately the center of the two movable contact members in the lateral direction.

[0011] 1 to 3, the ultrasonic flowmeter 1 according to this embodiment is a clamp-on type ultrasonic flowmeter that measures the flow rate in a pipe C using a transit time difference method and is fixed to the pipe C using two band-shaped bands B. The ultrasonic flowmeter 1 includes a converter 2, a pressing member 3, two transmitters / receivers 4, a guide member 5, two movable contact members 6, and four biasing members 7. When measuring the flow rate in the pipe C, the ultrasonic flowmeter 1 transmits ultrasonic waves from one transmitter / receiver 4 and receives them reflected by the inner surface of the pipe C by the other transmitter / receiver 4 (see FIGS. 11 and 12).

[0012] (Configuration of Converter) The configuration of the converter according to this embodiment will be described.

[0013] The converter 2 includes an input unit 21, a display unit 22, and a calculation unit (not shown), and a portion of the lower side of the housing that houses the converter 2 is configured as a mounting unit 23. The input unit 21 is configured to allow a user of the ultrasonic flowmeter 1 to input the size of the pipe C, which is the object of flow measurement, and the sonic speed of the fluid. The calculation unit calculates the positions of two transmitters / receivers 4, which will be described in detail later, and calculates the flow rate of the fluid flowing through the pipe C, based on the size of the pipe C and the sonic speed of the fluid input by the input unit 21. The display unit 22 displays the positions of the two transmitters / receivers 4 calculated by the calculation unit, and also displays the flow rate calculated by the calculation unit.

[0014] As shown in Figures 2, 3, and 5, the mounting portion 23 defines a generally box-shaped storage space with an open bottom, and this storage space accommodates the pressing member 3, two transceivers 4, a guide member 5, two movable contact members 6, and four biasing members 7. The mounting portion 23 is formed with two band insertion holes 231, two knob insertion holes 232, and two scales 233. Note that in this embodiment, one of the two knob insertion holes 232 and one of the two scales 233 are illustrated. The two band insertion holes 231 are holes that penetrate laterally near the front-rear end portions so that a band B can be inserted therethrough. Furthermore, the two band insertion holes 231 each communicate with the storage space so that the inserted band B can press the pressing member 3 downward.

[0015] The two knob insertion holes 232 are through holes extending in the front-rear direction on the side surface of the mounting portion 23. The two scales 233 indicate the placement positions of the two transceivers 4 in stages in the front-rear direction on the side surface of the mounting portion 23. In this embodiment, the two scales 233 each indicate the placement position of one transceiver 4 on six levels from 1 to 6 and the placement position of the other transceiver 4 on five levels from A to E. The display unit 22 displays any one of 1 to 6 and any one of A to E as the placement positions of the two transceivers 4 calculated by the calculation unit. As will be described in detail later, a user of the ultrasonic flowmeter 1 places the two transceivers 4 at the displayed placement positions prior to measuring the flow rate.

[0016] (Configuration of Pressing Member) The configuration of the pressing member according to this embodiment will be described.

[0017] As shown in FIG. 4 , the pressing member 3 has a base 30 and two flanges 31. The base 30 is elongated in the front-rear direction and is a generally plate-shaped member extending in the front-rear and lateral directions. The base 30 is formed long in the front-rear direction so as to be able to cover the entire upper surface of the guide member 5 positioned below it in the front-rear direction. The two flanges 31 are generally plate-shaped members that extend downward from the lateral ends of the base 30 a predetermined distance in the front-rear direction. Each of the two flanges 31 has a knob insertion hole 311, which is a through-hole extending in the front-rear direction, formed in correspondence with the knob insertion hole 232 formed on the side on which the flange 31 is provided. The pressing member 3 is fixed to the guide member 5.

[0018] The pressing member 3 is formed of a material having higher rigidity than the mounting portion 23, the guide member 5, and the two movable contact members 6. In this embodiment, the pressing member 3 is made of metal, and the mounting portion 23, the guide member 5, and the two movable contact members 6 are made of resin. As will be described in detail later, the pressing member 3 presses the two transceivers 4 against the piping C by the tension of the two bands B, and one end of each of the four biasing members 7 is fixed to the pressing member 3. In this way, by having the pressing member 3 perform functions that require high rigidity, other members in the ultrasonic flowmeter 1 can be formed of materials with lower rigidity, thereby reducing the manufacturing cost of the ultrasonic flowmeter 1.

[0019] (Configuration of Guide Member) The configuration of the guide member according to this embodiment will be described.

[0020] 4 and 5 , the guide member 5 defines a generally rectangular storage space that is elongated in the front-to-rear direction and has an open top. A partition wall 5W is formed within this storage space, dividing the storage space in the front-to-rear direction, so that the guide member 5 defines a guide space SA located on one side in the front-to-rear direction (the right side in FIG. 5 ) for guiding one transceiver 4 movably in the front-to-rear direction, and a guide space SB located on the other side in the front-to-rear direction (the left side in FIG. 5 ) for guiding the other transceiver 4 movably in the front-to-rear direction.

[0021] Two inner walls facing each other laterally in the guide space SA are formed with five pairs of locking grooves 51 at different positions in the front-to-rear direction. In other words, five pairs of locking grooves 51 are formed on the two inner walls. Each of these ten locking grooves 51 is a generally V-shaped recess extending in the vertical direction in a plan view (see FIGS. 7 and 8). The positions indicated by A to E on each of the two scales 233 of the mounting portion 23 correspond to the five pairs of locking grooves 51. Each of the two side walls defining the guide space SA is formed with a knob insertion hole 52, which is a through-hole extending in the front-to-rear direction. An opening 53 is formed in the wall forming the bottom surface of the guide space SA to expose a portion of the transceiver 4 housed in the guide space SA to the outside, as will be described in detail later (see FIGS. 7 and 8).

[0022] Six pairs of locking grooves 51 are formed in two laterally opposing inner walls of the guide space SB at different positions in the front-rear direction. Like the ten locking grooves 51 formed in the guide space SA, each of these twelve locking grooves 51 is a generally V-shaped recess extending in the up-down direction in a plan view. The positions indicated by 1 to 6 on each of the two scales 233 of the mounting portion 23 correspond to the six pairs of locking grooves 51. Each of the two side walls defining the guide space SB is formed with a knob insertion hole 52, which is a through-hole extending in the front-rear direction. An opening 53 is formed in the wall forming the bottom surface of the guide space SB to expose a portion of the transceiver 4 housed in the guide space SB to the outside, as will be described in detail later.

[0023] A support portion 54 is formed at an end of the guide member 5 that is outward in the front-rear direction from the guide space SA, supporting one of the movable contact members 6 so that it can move only in the up-down direction. Similarly, a support portion 54 is formed at an end of the guide member 5 that is outward in the front-rear direction from the guide space SB, supporting the other of the movable contact members 6 so that it can move only in the up-down direction. Each of these two support portions 54 has two insertion holes 541 that pass through the support portion 54 in the up-down direction, allowing the two biasing members 7 to be inserted therethrough. As shown in FIG. 5 , the guide member 5 is fixed to the mounting portion 23 by two screws 9 near one of the support portions 54 and near the other support portion 54. At this time, the two screws 9 are inserted into the base portion 30 of the pressing member 3 that is located between the mounting portion 23 and the guide member 5, thereby fixing the pressing member 3 to the guide member 5.

[0024] (Configuration of Transmitter / Receiver) The configuration and operation of the transceiver according to this embodiment will be described. FIG. 6 is a perspective view showing the configuration of the transceiver. FIGS. 7 and 8 are cross-sectional views showing the transceiver in an unlocked state and an locked state, respectively. FIGS. 9 and 10 are cross-sectional views showing the transceiver in a non-contact state and a contact state, respectively. The acoustic coupling member of the transceiver according to this embodiment will be described. FIGS. 11 and 12 are schematic side views showing strains that occur in the acoustic coupling member of the transceiver due to surface contact and point contact, respectively. FIGS. 7 and 8 show the transceiver, guide member, and pressing member cut along a plane that extends in the front-rear and lateral directions and passes through the plunger of the transceiver, respectively. FIGS. 9 and 10 show an ultrasonic flowmeter in which the mounting portion, pressing member, transceiver, guide member, and piping are cut along a plane that extends in the up-down and lateral directions and passes through the transceiver, respectively.

[0025] As shown in FIGS. 6 to 8 , the transceiver 4 includes a main body 40, two plungers 41, two knobs 42, and an acoustic coupling member 44. The main body 40 is a substantially rectangular resin housing that houses a transducer (not shown) therein, and a protrusion 43 that protrudes upward is formed on the top surface of the main body 40. The transducer is disposed on the main body 40 so that transmitted ultrasonic waves pass through the inner side of the bottom surface of the main body 40 in the front-to-rear direction and so that ultrasonic waves that have passed through the inner side of the bottom surface of the main body 40 in the front-to-rear direction can be received. The protrusion 43 is formed at a position on the bottom surface of the main body 40 that corresponds to the position through which the ultrasonic waves pass. In this embodiment, the protrusion 43 is formed on the inner side of the top surface of the main body 40 in the front-to-rear direction. Note that the propagation path of ultrasonic waves becomes shorter as the size of the piping C becomes smaller. Therefore, the transceiver 4 according to this embodiment is configured so that ultrasonic waves pass through the inner side of the bottom surface of the main body 40 in the front-to-rear direction, but it is not necessarily configured so that ultrasonic waves pass through the inner side of the bottom surface of the main body 40 in the front-to-rear direction.

[0026] As shown in Figures 7 and 8, the two plungers 41 are so-called ball plungers provided on both side surfaces of the main body 40 at the same positions in the front-to-rear direction. Each of the two plungers 41 has a housing portion 410, a ball 411, and a biasing member 412. The housing portion 410 is formed in a cylindrical shape with a closed bottom, and houses the ball 411 and the biasing member 412 in its internal space. The ball 411 is housed in the internal space of the housing portion 410 so that a portion of the ball 411 can protrude outward from the housing portion 410. The biasing member 412 is a compression coil spring that constantly biases the ball 411 so that a portion of the ball 411 protrudes outward from the housing portion 410.

[0027] As shown in Fig. 6, each of the two knobs 42 has a grip portion 421 and a shaft portion 422. Each of the two knobs 42 is coupled to the side surface of the main body 40 of the transceiver 4 with the shaft portion 422 inserted through the knob insertion hole 232 of the mounting portion 23, the knob insertion hole 311 of the pressing member 3, and the knob insertion hole 52 of the guide member 5. The grip portion 421 is exposed to the outside of the ultrasonic flowmeter 1 and is used when the user moves the transceiver 4. Also, as shown in Fig. 2, a pointer that points to the scale lines of the scale 233 is formed on a part of the grip portion 421.

[0028] The acoustic coupling member 44 is an elastic member provided on the bottom surface of the main body 40, and by pressing the acoustic coupling member 44 against the piping C so as to distort the acoustic coupling member 44, the propagation efficiency of ultrasonic waves between the transceiver 4 and the piping C is improved. As shown in Figures 9 and 10 , a protrusion that protrudes downward is formed in the lateral center of the acoustic coupling member 44. The two transceivers 4 are disposed in the guide member 5 so that the protrusions of the acoustic coupling member 44 can be exposed to the outside from openings 53 formed in the corresponding guide spaces SA and SB.

[0029] The two transceivers 4 are each guided in the front-to-rear direction by a guide member 5, and are locked by the guide member 5 at positions corresponding to the scale lines 1 to 6 or A to E. Here, the operation of the two transceivers 4 will be explained using one of the two transceivers 4 as an example.

[0030] 7 , when the two plungers 41 of the transceiver 4 are located at a position on the inner sidewall of the guide member 5 where there are no five pairs of locking grooves 51, the transceiver 4 is in an unlocked state where it is not locked in the front-to-rear direction relative to the guide member 5. At this time, the balls 411 of the two plungers 41 each come into contact with the inner sidewall of the guide member 5 and are drawn into the accommodation section 410.

[0031] On the other hand, as shown in FIG. 8 , when the two plungers 41 of the transceiver 4 are positioned at any of the five pairs of locking grooves 51 on the inner surface of the sidewall of the guide member 5, the transceiver 4 is locked in the front-to-rear direction relative to the guide member 5. At this time, the balls 411 exposed to the outside of each of the two plungers 41 are partially engaged in the locking grooves 51 and biased by the biasing member 412. The user can change the transceiver 4 from the locked state to the unlocked state by moving the transceiver 4 in either the front or rear direction against the biasing member 412. Since all of the locking grooves 51 formed in the guide member 5 extend vertically, even when the transceiver 4 is locked, the transceiver 4 is not locked in the vertical direction and can move vertically. The two plungers 41 may be other components configured to be biased to lock into the locking grooves 51 by, for example, a snap fit, and to be unlocked by moving the transceiver 4 against the biasing force. Furthermore, each of the two transmitters / receivers 4 may be provided with at least one plunger 41 .

[0032] The user fixes the ultrasonic flowmeter 1 to the pipe C by wrapping the two bands B, which are inserted into the two band insertion holes 231 of the mounting portion 23, around the pipe C. At this time, as will be described in detail later, the two movable contact members 6 come into contact with the pipe C. Furthermore, the user locks each of the two transceivers 4 in a pair of locking grooves 51 corresponding to the placement positions displayed on the display unit 22. Next, the user adjusts the two bands B to tighten the pipe C. At this time, the tension of the two bands B applies a load downward, i.e., toward the pipe C, to both front-rear direction end portions of the pressing member 3, thereby pressing the acoustic coupling members 44 of the two transceivers 4 located below the pressing member 3 against the pipe C.

[0033] Here, the effect of the protrusions 43 provided on the main body 40 will be described. Fig. 11 shows two transceivers 4A that do not have protrusions 43 provided on the upper surface of the main body 40. When the two transceivers 4A are pressed downward by the pressing member 3, a load is applied to both ends of the pressing member 3, causing an upward moment at approximately the center of the pressing member 3 in the front-to-rear direction. This causes a moment that moves the acoustic coupling members 44 of the two transceivers 4, which are in surface contact with the pressing member 3, away from the piping C on the inner front-to-rear direction sides. This reduces distortion on the inner front-to-rear direction sides of the acoustic coupling members 44, i.e., at the locations of the acoustic coupling members 44 through which ultrasonic waves pass, and reduces the propagation efficiency of ultrasonic waves between the transceivers 4 and the piping C.

[0034] On the other hand, as shown in Figure 12, in each of the two transmitter / receivers 4 having a protrusion 43 on the inner side in the front-to-rear direction of the main body 40, the protrusion 43 comes into point contact with the pressing member 3, which increases the distortion on the inner side in the front-to-rear direction of the acoustic coupling member 44 located below the protrusion 43, thereby improving the propagation efficiency of ultrasonic waves between the transmitter / receiver 4 and the piping C.

[0035] (Configuration of Movable Contact Member) The configuration and operation of the movable contact member according to this embodiment will be described. Figures 13 and 14 are cross-sectional views showing the movable contact member being pressed against a small-diameter pipe and a large-diameter pipe, respectively. Note that Figures 13 and 14 show the ultrasonic flowmeter and the pipe extending in the vertical and lateral directions, respectively, cut by a plane that passes through the movable contact member and two springs.

[0036] 4, 13, and 14, the two movable contact members 6 are each provided so as to be movable a predetermined distance in the up-down direction relative to the guide member 5. Each of the two movable contact members 6 is formed with a valley-shaped bottom 61 and two support holes 62. The valley-shaped bottom 61 is formed in the bottom surface of the movable contact member 6 in the shape of a recessed valley having two inclined portions that slope downward from the inner side in the left-right direction to the outer side in the left-right direction. The two support holes 62 are each a blind hole formed in the top surface of the movable contact member 6 so that the biasing member 7 can be inserted from above.

[0037] Two biasing members 7 are inserted into the two support holes 62, and the lower ends of the two biasing members 7 are supported by the bottom surfaces of the two support holes 62. As described above, the two biasing members 7 are inserted into the two insertion holes 541 formed in the guide member 5, and the upper ends of the two biasing members 7 are supported by the pressing member 3, which has higher rigidity than the other members. In this way, when the ultrasonic flowmeter 1 is fixed to the piping C, the two movable contact members 6 are each biased downward by the two biasing members 7, i.e., toward the piping C to which the ultrasonic flowmeter 1 is fixed.

[0038] With these two movable contact members 6, the ultrasonic flowmeter 1 is positioned lower when it is fixed to a pipe C1 having a smaller diameter as shown in Fig. 13, and is positioned higher when it is fixed to a pipe C2 having a larger diameter as shown in Fig. 14. In this way, the ultrasonic flowmeter 1 according to this embodiment can be appropriately fixed to pipes C having various diameters.

[0039] By making the movable contact member 6, rather than the transceiver 4, the object of biasing by the biasing member 7, there is no decrease in propagation efficiency due to a decrease in biasing force, no buckling of the biasing member 7 due to the transceiver 4 moving forward and backward, and no interference with the cable connected to the transceiver 4.

[0040] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its modifications are included within the scope and spirit of the invention, and are also included in the inventions described in the claims and their equivalents.

[0041] REFERENCE SIGNS LIST 1 ultrasonic flowmeter 2 transducer 3 pressing member 4 transmitter / receiver 5 guide member 6 movable contact member

Claims

1. An ultrasonic flowmeter for measuring the flow rate of a fluid flowing through a pipe by the propagation time difference method, comprising: two transceivers for transmitting or receiving ultrasonic waves; a guide member extending in the extending direction of the pipe and guiding the two transceivers in the extending direction of the pipe; and a pressing member extending in the extending direction of the guide member, wherein when the ultrasonic flowmeter is fixed to the pipe by winding two bands respectively corresponding to one side and the other side of the pressing member around the one side and the other side of the pressing member and winding them around the pipe, the pressing member for pressing the two transceivers against the pipe.

2. The ultrasonic flowmeter according to claim 1, wherein an acoustic coupling member, which is an elastic member, is provided on the bottom surface in contact with the pipe in a state where the ultrasonic flowmeter is fixed to the pipe for each of the two transceivers, and a protruding portion protruding toward the pressing member side is provided on the upper surface pressed by the pressing member.

3. The ultrasonic flowmeter according to claim 2, wherein the protruding portion is formed on the side where ultrasonic waves pass through in the acoustic coupling member in the extending direction of the pipe.

4. The ultrasonic flowmeter according to any one of claims 1 to 3, further comprising a movable contact member movably provided on the guide member in a direction approaching the pipe and biased toward the pipe in a state where the ultrasonic flowmeter is fixed to the pipe.

5. The ultrasonic flowmeter according to claim 4, wherein at least one or more engaged portions are provided for each of the two transceivers, and the guide member is formed with a plurality of locking grooves that lock the at least one or more engaged portions of each of the two transceivers in the extending direction of the pipe and extend in a direction approaching the pipe.

6. The ultrasonic flowmeter according to claim 5, wherein the at least one or more engaged portions are biased to be engaged with any one of the plurality of locking grooves, and when the transceiver provided with the engaged portion is moved in the extending direction of the pipe against the biasing force, the engagement with the locking groove is released.

7. The ultrasonic flowmeter according to claim 6, further comprising a converter for calculating the flow rate of the pipe based on the ultrasonic waves transmitted and received by the two transceivers.

8. The ultrasonic flowmeter according to claim 7, wherein two band insertion holes for inserting the two bands are formed in the transducer.

9. The transducer defines an accommodation space for accommodating the two transceivers, the guide member, the pressing member, and the two movable contact members, and the two band insertion holes communicate with the accommodation space. The ultrasonic flowmeter according to claim 8.

10. The ultrasonic flowmeter according to claim 9, wherein the pressing member has higher rigidity than the guide member.

11. The ultrasonic flowmeter according to claim 10, wherein one end of a biasing member that biases the two movable contact members is supported by the pressing member.

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