Levitation spreaders

Abstract

A levitating sprayer attached to a vehicle for spraying calcium chloride or fertilizer is disclosed. The disclosed levitating sprayer comprises: a storage container for receiving calcium chloride or fertilizer; a spraying plate located at the bottom of the storage container and rotating to spray calcium chloride or fertilizer discharged through a discharge assembly; a blocking plate for blocking spraying toward the front where the vehicle is located when calcium chloride or fertilizer is sprayed by the rotation of the spraying plate; a motor unit located at the bottom of the spraying plate to rotate the spraying plate; a discharge assembly coupled to the bottom of the storage container to block a part of the discharge hole of the storage container and located at the top of the spraying plate, and connected to the motor unit so as to be rotatable with the spraying plate by the motor unit; a connecting bracket coupled to the side of the motor unit so as to be inserted into and coupled to a towing bracket provided on the vehicle; an operating unit for controlling the operation of the motor unit; a socket unit connected to a lighting equipment socket of the vehicle to supply power for the operation of the motor unit; and a fixing plate for maintaining the position of the discharge assembly.

Description

Technology Field

[0001] The present invention relates to a sprayer for solid materials such as calcium chloride, sand, or fertilizer attached to a vehicle, and specifically, to a levitating sprayer for spraying calcium chloride, sand, or fertilizer, etc., attached to a vehicle such as a general vehicle, truck, snowplow, four-wheel drive bike, or tractor. Background Technology

[0003] In areas where temperatures drop below freezing, de-icing agents such as calcium chloride or sand are sprayed to prevent freezing of the road surface. Generally, de-icing agents are sprayed by connecting a sprayer to a snowplow or other work vehicle, and examples of this are illustrated in FIGS. 1 and 2. As shown in FIG. 1, a towed sprayer structure has been widely used by mounting a sprayer (11, 12) on a trailer (10) equipped with wheels. However, the trailer-type sprayer structure shown in FIG. 1 had the disadvantage that, due to the wheels separately provided on the trailer, the spraying of the de-icing agent by the sprayer was not uniform on roads with uneven surfaces, and a large amount of de-icing agent was wasted below the de-icing agent storage container (11) due to the rattling of the trailer. To compensate for the disadvantages of the trailer-type sprayer structure shown in FIG. 1, an example of a sprayer structure that is connected to a towing bracket provided on a vehicle is illustrated in FIG. 2.

[0004] Conventional de-icing agent spreaders, such as those exemplified in FIGS. 1 and 2, have the problem of difficulty in controlling the amount of de-icing agent sprayed. Although an example of controlling the amount of de-icing agent sprayed is disclosed in Korean Registered Patent No. 10-2620969 (registered on December 29, 2023), the above document merely describes a method in which an operator rotates and sets a component called an opening / closing pipe at the bottom of a calcium chloride storage container before spraying. In a de-icing agent spreader with this structure, there is the inconvenience of having to stop the vehicle and the spreader to adjust the amount of de-icing agent sprayed.

[0005] Therefore, there is a need for a new type of spreader that can dynamically adjust the amount of de-icing agent sprayed without stopping vehicle operation while continuously spraying the agent. Prior art literature

[0007] Republic of Korea Published Patent No. 10-2017-0110937 (Published October 12, 2017) Republic of Korea Registered Patent No. 10-2620969 (Registered December 29, 2023)

[0008] Attachable Calcium Chloride Spreader : https: / / m.cleanermall.co.kr / product / 염화칼람-살포기-부착형-sp-1075x / 4542 / The problem to be solved

[0009] The problem that the present invention aims to solve is to provide a vehicle-mounted calcium chloride or fertilizer spreader with an improved structure for controlling the amount of de-icing agent (or fertilizer) being spread, while reducing the amount of de-icing agent wasted due to uneven spreading, which is a typical disadvantage of conventional trailer-type de-icing agent or fertilizer spreaders.

[0010] Another problem that the present invention aims to solve is to provide a vehicle-mounted calcium chloride or fertilizer spreader with an improved structure capable of adjusting the amount of de-icing agent (or fertilizer) sprayed in real time and dynamically without stopping the operation of the vehicle and the spreader. means of solving the problem

[0012] A levitating sprayer according to one aspect of the present invention for solving the above problem comprises: a storage container for receiving calcium chloride or fertilizer; a spraying plate located at the bottom of the storage container and rotating to spray calcium chloride or fertilizer discharged through a discharge hole formed at the bottom of the storage container; a blocking plate for blocking spraying toward the front where the vehicle is located when calcium chloride or fertilizer is sprayed by the rotation of the spraying plate; a motor unit located at the bottom of the spraying plate to rotate the spraying plate; a discharge assembly coupled to the bottom of the storage container to block a part of the discharge hole of the storage container, located at the top of the spraying plate, and connected to the motor unit so as to be able to rotate simultaneously with the spraying plate by the motor unit; a connecting bracket coupled to the side of the motor unit so as to be inserted into and coupled to a towing bracket provided on the vehicle; an operating unit for controlling the operation of the motor unit; a socket unit connected to a lighting equipment socket of the vehicle to supply power for the operation of the motor unit; and a device for maintaining the position of the discharge assembly. It is characterized by including a fixed plate.

[0013] According to one embodiment, the discharge assembly comprises a stirring part located inside the storage container, an extension shaft extending from the spraying plate so that the stirring part can rotate simultaneously with the spraying plate by the motor part—the stirring part is connected to the upper end of the extension shaft—a discharge amount control part located on the circumference of the extension shaft and below the stirring part to control the amount of calcium chloride or fertilizer discharged through the discharge hole of the storage container, and a cover part including a cover body to cover the outside of the discharge amount control part and a cover head connected to the upper end of the cover body and formed to have a diameter larger than the diameter of the discharge hole of the storage container so that the cover body is maintained on the inner surface of the storage container.

[0014] According to one embodiment, the operating unit includes an off selection unit for turning off the motor unit, a first stage selection unit for rotating the motor unit at a relatively low speed, a second stage selection unit for rotating the motor unit at a relatively high speed compared to the first stage, a third stage selection unit for rotating the motor unit at a relatively high speed compared to the second stage, and a fourth stage selection unit for rotating the motor unit at a relatively high speed compared to the third stage.

[0015] According to one embodiment, the discharge amount control unit is adjusted so that when the first stage selection unit is selected by the operating unit, the opening is opened to have a first diameter; when the second stage selection unit is selected by the operating unit, the opening is adjusted so that it has a second diameter that is relatively larger than the first diameter; when the third stage selection unit is selected by the operating unit, the opening is adjusted so that it has a third diameter that is relatively larger than the second diameter; and when the fourth stage selection unit is selected by the operating unit, the opening is adjusted so that it has a fourth diameter that is relatively larger than the third diameter.

[0016] According to one embodiment, the discharge amount control unit may be formed to have a spiral path to lengthen the path from the discharge hole to the spray plate. Effects of the invention

[0018] The present invention provides a levitating sprayer attached to a vehicle, thereby reducing the amount of de-icing agent (or fertilizer) wasted due to uneven distribution on the road surface—a disadvantage of conventional sprayers—while also controlling the amount of de-icing agent (or fertilizer) sprayed. Furthermore, it has the effect of controlling the amount of de-icing agent (or fertilizer) sprayed in real-time and dynamically without operating the sprayer or stopping the vehicle to which the sprayer is attached. Brief explanation of the drawing

[0019] FIGS. 1 and 2 are drawings illustrating examples of conventional de-icing agent spreaders, and FIGS. 3a and 3b are drawings showing the features of a levitating sprayer (100) according to one embodiment of the present invention, and FIG. 4 is a drawing for explaining the relationship between a storage tank (110), a motor unit (130), a spray plate (170), and a discharge assembly (180) in a levitating sprayer (100) according to one embodiment of the present invention, and FIG. 5 is a drawing showing the state in which the lid (120) covering the upper part of the storage container (110) in a levitating sprayer (100) according to one embodiment of the present invention is opened, and FIG. 6 is a drawing showing the state in which the storage tank (110) in FIG. 5 has been removed to explain the relationship between the fixed plate (P1) and the discharge assembly (180) in a levitating sprayer (100) according to one embodiment of the present invention. FIGS. 7a, 7b, and 7c are drawings for illustrating examples of a discharge assembly (180) in a levitating sprayer (100) according to one embodiment of the present invention, and FIG. 8 is a drawing for explaining a specific operation example of the discharge amount control unit (185b) in the discharge assembly (180) shown in FIG. 7c, and FIG. 9 is a drawing to show the discharge hole (H2) of the storage container (110). Specific details for implementing the invention

[0020] The present invention basically relates to a vehicle-mounted levitating sprayer for spraying calcium chloride or fertilizer, capable of controlling the discharge amount in real-time and dynamically. Since it is attached to a vehicle without using wheels and takes the form of being levitating in the air, it is referred to as a levitating sprayer within this specification.

[0021] Preferred embodiments of the present invention will be described below with reference to the attached drawings. It should be noted that the attached drawings and embodiments are simplified and illustrative for the purpose of helping those skilled in the art understand the present invention.

[0022] FIGS. 3A and 3B are drawings showing features of a levitating sprayer (100) according to an embodiment of the present invention, FIG. 4 is a drawing for explaining the relationship between a storage tank (110), a motor unit (130), a spraying plate (170), and a discharge assembly (180) in a levitating sprayer (100) according to an embodiment of the present invention, FIG. 5 is a drawing showing the state in which the lid (120) covering the upper part of the storage tank (110) in the levitating sprayer (100) is opened, FIG. 6 is a drawing showing the state in which the storage tank (110) is removed from FIG. 5 to explain the relationship between a fixed plate (P1) and a discharge assembly (180) in a levitating sprayer (100) according to an embodiment of the present invention, FIG. 7A, FIG. 7B and FIG. 7C are drawings for explaining examples of a discharge assembly (180) in a levitating sprayer (100) according to an embodiment of the present invention, and FIG. 8 FIG. 7c is a drawing for explaining a specific operation example of the discharge volume control part (185b) in the discharge assembly (180) shown in FIG. 7c, and FIG. 9 is a drawing for showing the discharge hole (H2) of the storage container (110).

[0023] First, a levitating sprayer (100) according to one embodiment of the present invention will be described with reference to FIGS. 3a and 3b. The vehicle-mounted calcium chloride or fertilizer sprayer (100) includes a storage tank (110), a motor part (130), a blocking plate (140), a connecting bracket (150), an operating part (160), a spraying plate (170), a discharge assembly (180), a socket part (190), and a fixing plate (P1).

[0024] The storage container (110) is a component provided with a receiving space to accommodate calcium chloride or fertilizer inside. The upper part of the storage container (110) is covered by a storage container cover (120), and a cover fixing device (125) is provided to secure the storage container cover (120) while it is attached to the storage container (110).

[0025] The motor unit (130) is located at the bottom of the spray plate (170) and is a component for rotating the spray plate (170). The motor unit (130) rotates not only the spray plate (170) but also the discharge assembly (180) (specifically, the stirring unit (183)) simultaneously with the spray plate (170). The operation of the motor unit (130) is controlled by the operating unit (160).

[0026] The blocking plate (140) is a component for blocking the spraying of calcium chloride or fertilizer discharged through the discharge hole (see H2 in FIG. 9) of the storage tank (110) by centrifugal force as the spraying plate (170) rotates, i.e., the forward direction in which the vehicle to which the sprayer (100) is attached is located. In other words, it is intended to ensure that the sprayed calcium chloride or fertilizer is not sprayed toward the vehicle but is sprayed only toward the rear.

[0027] The connecting bracket (150) is a component that is inserted into a towing bracket (not shown) provided in the vehicle and connected using a connecting pin (not shown). The connecting bracket (150) is connected to the side of the motor part (130).

[0028] The control unit (160) is a component for controlling the operation of the motor unit (130). It is preferable that the control unit (160) be wired to be located in the front where the operator's hand can reach (e.g., near the handle) so that it can be easily operated in real time during operation. As described below, the control unit (160) is configured to allow the motor unit (130) to be selected in multiple stages (e.g., from off to 1st, 2nd, 3rd, and 4th stages).

[0029] The spraying plate (170) is a component for spraying calcium chloride or fertilizer that is discharged through a discharge hole formed at the bottom of the storage tank (110) (strictly speaking, through the discharge assembly (180) since the discharge assembly (180) is located in the middle). A plurality of spraying blades (175) are formed in the radial direction on the spraying plate (170). Although the number of spraying blades (175) is shown as four in the drawing, it is not limited to this number.

[0030] The discharge assembly (180) is coupled to the lower part of the storage tank (110) to block a part of the discharge hole (H2 in FIG. 9) of the storage tank (110), is located on the upper part of the spray plate (170), and is connected to the motor part (130) so as to be rotatable simultaneously with the spray plate (170) by the motor part (130). Specific examples regarding the discharge assembly (180) are illustrated in FIG. 7a to 7c, so they will be described later with reference thereto.

[0031] The socket portion (190) is connected to a socket (not shown) for the vehicle's lighting equipment to supply power for the operation of the motor portion (130).

[0032] The fixed plate (P1) is a component for maintaining the position of the discharge assembly (180). In addition to the fixed plate (P1), there are a plurality of brackets (B1 to B4) to stably maintain the structure of the sprayer (100) of the present invention. Bracket B1 is a bracket for stably maintaining the connection between the connecting bracket (150) and the fixed plate (P1), and bracket B2 is a bracket coupled to one end of the fixed plate (P1) to facilitate easy connection between bracket B1 and the fixed plate (P1). Bracket B3 is an inverted U-shaped structure and is a bracket for stably fixing the storage tank (110), the motor part (130), and the fixed plate (P1), and bracket B4 is a bracket coupled vertically to bracket B3 and connected to the outer middle part of the storage tank (110) to stably fix the storage tank (110). Reference numeral C1 symbolically represents the electrical wiring between the control unit (160) and the socket unit (190), and reference numeral C2 represents the wiring for the electrical connection between the motor unit (180) and the socket unit (190). Although not shown in the drawing, C1 and C2 are wired to be electrically connected.

[0033] FIG. 4 is a drawing for explaining the relationship between a storage tank (110), a motor unit (130), a spraying plate (170), and a discharge assembly (180). Referring to FIG. 4, the motor unit (130) is located at the bottom, the spraying plate (170) is located above it (a plurality of spraying blades (175) are formed on the spraying plate (170)), the discharge assembly (180) is located above it, and the storage tank (110) is located above the discharge assembly (180). As in FIG. 3a and FIG. 3b, the motor unit (130) is symbolically represented only as a motor box in the drawing, but a motor and a rotating shaft are located inside it, and the rotating shaft rotates to rotate the spraying plate (170) and the stirring unit (183) of the discharge assembly (180).

[0034] FIG. 5 is a drawing showing the lid (120) covering the upper part of the storage container (110) in an open state. Referring to FIG. 5, a discharge assembly (180) is coupled to block a part of the discharge hole formed at the bottom of the storage container (110).

[0035] FIG. 6 is a drawing showing the state in which the storage container (110) in FIG. 5 has been removed to explain the relationship between the fixed plate (P1) and the discharge assembly (180). Referring to FIG. 6, the fixed plate (P1) is fixed by the connecting bracket (150) and bracket B1, and in this state, the fixed plate (P1) stably maintains the position of the discharge assembly (180). In FIG. 6, reference numeral H1 is in communication with a part of the discharge hole of the storage container (110), and since the discharge assembly (180) is connected to the bottom of the storage container (110), the calcium chloride or fertilizer contained in the storage container (110) is discharged to the outside (towards the spraying plate (170)) only through H1.

[0036] FIGS. 7a to 7c are drawings for explaining examples of a discharge assembly (180). First, referring to FIG. 7a, the discharge assembly (180) includes a stirring part (183) located inside a storage container (110), an extension shaft (184) extending from a spray plate (170) so that the stirring part (183) can rotate simultaneously with the spray plate (170) by means of a motor part (130), a discharge amount control part (185a, 185b, see FIG. 7b and FIG. 7c) located on the circumference of the extension shaft (184) and below the stirring part (183) to control the amount of calcium chloride or fertilizer discharged through the discharge hole of the storage container (110), and a cover part (181, 182). The stirring section (183) is connected to the upper end of the extension shaft (184) and rotates together with the spreading plate (170) when the motor section (130) is driven, thereby dissolving calcium chloride or fertilizer that is stuck or clumped together inside the storage container (110) and allowing it to be smoothly discharged through the discharge hole at the bottom. The discharge amount control section (185a, 185b) is illustrated in FIG. 7b and FIG. 7c, but is not limited to these examples and can be implemented in various structures or shapes. The cover portion (181, 182) is configured to have a cover body (181) and a cover head (182), the cover body (181) is a component for covering the outside of the discharge volume control portion (185a, 185b), and the cover head (182) is connected to the top of the cover body (181) and is formed to have a diameter larger than the diameter of the discharge hole (H2 in FIG. 9) of the storage container (110) so that the cover body (181) is connected to the storage container (110) and does not flow or fall out.

[0037] Referring to FIG. 7b, the discharge volume control unit (185) is configured to have a spiral path descending along the central extension axis (184) so ​​as to control the amount of calcium chloride or fertilizer discharged.

[0038] Referring to FIG. 7c and FIG. 8 together, the discharge volume control unit (185b) may be configured so that the diameter of the opening is adjusted according to the rotational speed of the motor unit (130). That is, the operating unit (160) may include an off selection unit for turning off the motor unit (130), a first stage selection unit for rotating the motor unit (130) at a relatively low speed, a second stage selection unit for rotating the motor unit (130) at a relatively high speed compared to the first stage, a third stage selection unit for rotating the motor unit (130) at a relatively high speed compared to the second stage, and a fourth stage selection unit for rotating the motor unit (130) at a relatively high speed compared to the third stage. Here, it is configured to have four stages from the first stage to the fourth stage, but it may also be implemented with two stages, three stages, or five stages or more.

[0039] By operating the control unit (160) in this manner, the discharge volume control unit (185b) is adjusted so that when the first stage selection unit is selected by the control unit (160), the rotation shaft rotates to a speed of V1 by the operation of the motor unit (130), causing the spraying plate (170) to rotate at a relatively low speed, and at this time, the opening of the discharge volume control unit (185b) is adjusted to have a first diameter (r1) (see FIG. 8 (a)). Since the spraying plate (170) rotates at a relatively low speed in the first stage, the centrifugal force due to the rotation of the spraying plate (170) is also relatively small, so the amount of calcium chloride or fertilizer supplied (discharged) to the spraying plate (170) can be relatively small. Meanwhile, when the 2nd stage selection unit is selected by the operation of the control unit (160), the rotation shaft is rotated by the operation of the motor unit (130) to have a speed of V2, so that the spraying plate (170) rotates at a speed relatively faster than V1, and at this time, the opening is adjusted to have a second diameter (r2) which is relatively larger than the first diameter (see FIG. 8 (b)). Since the spraying plate (170) rotates faster in the 2nd stage than in the 1st stage, the centrifugal force due to the rotation of the spraying plate (170) also increases relatively more than in the 1st stage, so the amount of calcium chloride or fertilizer supplied to the spraying plate (170) must be supplied relatively more than in the 1st stage so that the spraying of calcium chloride or fertilizer can proceed smoothly. Similarly, when the 3rd stage selection unit is selected by the operation of the control unit (160), the rotation axis is rotated by the operation of the motor unit (130) to have a speed of V3, so that the spray plate (170) rotates at a speed relatively faster than V2, and at this time, the opening is adjusted to have a third diameter (r3) which is relatively larger than the second diameter (see (c) of FIG. 8).This is because, in the case of the 3rd stage, the spraying plate (170) rotates faster than in the case of the 2nd stage, and thus the centrifugal force resulting from the rotation of the spraying plate (170) also increases relatively more than in the case of the 2nd stage; therefore, the amount of calcium chloride or fertilizer supplied to the spraying plate (170) must be supplied relatively more than in the case of the 2nd stage so that the spraying of calcium chloride or fertilizer can proceed smoothly. Additionally, when the 4th stage selection unit is selected by the operation of the control unit (160), the rotation shaft rotates to have a speed of V4 by the operation of the motor unit (130), so that the spraying plate (170) rotates at a speed relatively faster than V3, and at this time, the opening is adjusted to open to have a 4th diameter (r4) which is a relatively larger diameter than the 3rd diameter (see (d) of FIG. 8). This is because, in the case of the 4th stage, the spraying plate (170) rotates faster than in the case of the 3rd stage, and thus the centrifugal force resulting from the rotation of the spraying plate (170) also increases relatively more than in the case of the 3rd stage, so the amount of calcium chloride or fertilizer supplied to the spraying plate (170) must be supplied relatively more than in the case of the 3rd stage so that the spraying of calcium chloride or fertilizer can proceed smoothly. In this way, the diameter of the opening of the discharge amount control unit (185b) is adjusted in conjunction with the rotation speed of the motor by the control unit (160).

[0040] If, even though the rotational speed of the motor unit (130) is only at level 1, the opening of the discharge volume control unit (185b) is configured to have a large diameter of r4 as in (d), then the amount of calcium chloride or fertilizer falling through the discharge hole increases, and thus the amount of calcium chloride or fertilizer that is discarded downwards cannot be evenly distributed by the rotation of the spreading plate (170) alone, and conversely, even though the rotational speed of the motor unit (130) is set to level 4 to increase the spreading range of calcium chloride or fertilizer on the road surface, if the opening of the discharge volume control unit (185b) is configured to have a small diameter of r1 as in (a), then the amount of calcium chloride or fertilizer supplied is too small compared to the rapid rotation of the spreading plate (170), so it cannot cover a wide range of spreading on the road surface. Accordingly, in order to increase or decrease the discharge amount in correspondence with the rotational speed of the motor part (130) and the rotational speed of the spray plate (170) accordingly, the diameter of the opening of the discharge amount control part (185b) can also be configured to be larger or smaller.

[0041] Through this configuration, the vehicle-mounted calcium chloride or fertilizer sprayer (100) of the present invention has the advantage of minimizing the amount of wasted calcium chloride or fertilizer and dynamically adjusting the amount of calcium chloride or fertilizer sprayed in real time without stopping the vehicle or stopping the operation of the sprayer while the sprayer is in operation. Explanation of the symbols

[0043] 100 : The levitating sprayer of the present invention 110 : Storage container 120 : Lid 130 : Motor section 140 : Block plate 150 : Connection bracket 160 : Control panel 170 : Spray plate 180 : Discharge assembly 190 : Socket part P1 : Fixed plate

Claims

Claim 1 A levitating sprayer attached to a vehicle for spraying calcium chloride or fertilizer, comprising: a storage container (110) for receiving calcium chloride or fertilizer; a spraying plate (170) located at the bottom of the storage container and rotating to spray calcium chloride or fertilizer discharged through a discharge assembly; a blocking plate (140) for blocking spraying toward the front where the vehicle is located when the calcium chloride or fertilizer is sprayed by the rotation of the spraying plate; a motor unit (130) located at the bottom of the spraying plate and rotating the spraying plate; a discharge assembly (180) coupled to the bottom of the storage container (110) to block a part of the discharge hole of the storage container (110), located at the top of the spraying plate, and connected to the motor unit so as to be able to rotate simultaneously with the spraying plate by the motor unit; and a connecting bracket (150) coupled to the side of the motor unit so as to be inserted into and coupled to a towing bracket provided on the vehicle. A levitating sprayer characterized by comprising: an operating unit (160) for controlling the operation of the motor unit; a socket unit (190) connected to a socket for lighting equipment of the vehicle to supply power for the operation of the motor unit; and a fixing plate (P1) for maintaining the position of the discharge assembly. Claim 2 A levitating sprayer according to claim 1, wherein the discharge assembly (180) comprises: a stirring part (183) located inside the storage container; an extension shaft (184) extending from the spray plate so that the stirring part can rotate simultaneously with the spray plate by the motor part - the stirring part is connected to the upper end of the extension shaft -; a discharge amount control part located on the circumference of the extension shaft and below the stirring part to control the amount of calcium chloride or fertilizer discharged through the discharge hole of the storage container; a cover body (181) for covering the outside of the discharge amount control part; and a cover head (182) connected to the upper end of the cover body and formed to have a diameter larger than the diameter of the discharge hole of the storage container so that the cover body is maintained on the inner surface of the storage container. Claim 3 A levitating sprayer according to claim 2, wherein the operating unit comprises an off selection unit for turning off the motor unit, a first stage selection unit for rotating the motor unit at a relatively low speed, a second stage selection unit for rotating the motor unit at a relatively high speed compared to the first stage, a third stage selection unit for rotating the motor unit at a relatively high speed compared to the second stage, and a fourth stage selection unit for rotating the motor unit at a relatively high speed compared to the third stage. Claim 4 A levitating sprayer according to claim 3, wherein the discharge amount control unit is adjusted so that when the first stage selection unit is selected by the operating unit, the opening is adjusted to have a first diameter; when the second stage selection unit is selected by the operating unit, the opening is adjusted to have a second diameter that is relatively larger than the first diameter; when the third stage selection unit is selected by the operating unit, the opening is adjusted to have a third diameter that is relatively larger than the second diameter; and when the fourth stage selection unit is selected by the operating unit, the opening is adjusted to have a fourth diameter that is relatively larger than the third diameter.

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