Pusher robot

Abstract

The utility model relates to a push material equipment technical field provides a kind of push material robot, including mobile platform, first connecting arm, second connecting arm, push material piece, drive assembly and auger, first connecting arm and second connecting arm are spaced apart on mobile platform, the length of second connecting arm is greater than the length of first connecting arm;The end of first connecting arm and the end of second connecting arm are all protruding towards the side of mobile platform;The side of push material piece is connected with first connecting arm and second connecting arm, and the other side is provided with open bin;Drive assembly is located in push material piece;It is located in open bin and is connected with drive assembly transmission. Through the first connecting arm and second connecting arm of unequal length connection bearing push material piece, make push material piece relative to mobile platform inclination, and then through the auger of being arranged similarly inclination, towards the side of mobile platform inclination push feed, can reduce lateral resistance, avoid robot skidding.

Description

Technical Field

[0001] This utility model relates to the field of material pushing equipment technology, and in particular to a material pushing robot. Background Technology

[0002] In the daily management of large-scale farms, animals often push against the feed during feeding, preventing feed far from the fence from being effectively consumed. This necessitates repeated manual repositioning of the scattered feed back to the fence. Current technology is beginning to explore using general-purpose livestock feed-pushing robots to accomplish this task.

[0003] However, when these robots push materials, the lateral resistance generated by the feed pile can cause the robot's drive wheels to slip, or even cause the robot to tilt to one side, making it impossible for the robot to move along the predetermined trajectory and accurately push the feed into place, thus reducing the reliability of the equipment. Utility Model Content

[0004] The purpose of this invention is to provide a pushing robot that solves the problem that existing robots are prone to slippage due to the counter-pushing force generated by the feed pile when pushing materials, resulting in insufficient reliability during use.

[0005] The technical solution of this utility model is as follows: A material pushing robot, comprising: Mobile platform; A first connecting arm and a second connecting arm are spaced apart on the mobile platform, the length of the second connecting arm is greater than the length of the first connecting arm; and the ends of both the first and second connecting arms protrude toward the side of the mobile platform. The pusher is connected to the first connecting arm and the second connecting arm on one side, and has an open hopper on the other side. A drive component is provided on the pusher; The auger is located inside the open hopper and is connected to the drive assembly for transmission.

[0006] Compared with the prior art, the embodiments of this utility model have the following advantages: The feeding robot provided by this utility model has a first connecting arm and a second connecting arm of different lengths set on the mobile platform. The feeding component set at the end of the first connecting arm and the second connecting arm is tilted relative to the mobile platform. Therefore, during the feeding process, the counter-thrust generated by the auger rotating and accumulating feed pile is also tilted, rather than completely perpendicular to the direction of travel of the mobile platform. Thus, the lateral thrust that the mobile platform needs to overcome during travel is reduced, which can reduce slippage, avoid deviation from the travel route, reduce the probability of collision with fences, animals, etc., and improve the reliability and safety of the equipment. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the structure of a material pushing robot according to an embodiment of the present invention; Figure 2 This is an exploded view of the structure of a material-pushing robot according to an embodiment of the present invention; Figure 3 This is an exploded view of a portion of the structure of a material-pushing robot according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the pusher component according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the push plate according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of a transmission component according to an embodiment of the present invention; Figure 7 This is an exploded view of the supporting back plate according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the auger structure according to an embodiment of the present invention; Figure 9 This is an exploded view of a portion of the structure of an embodiment of the present invention.

[0009] Among them, 10 is a mobile platform; 20 is a first connecting arm; 30 is a second connecting arm; 40 is a mounting plate; 50 is a pusher; 510 is a support back plate; 511 is a connecting plate; 512 is a cover plate; 520 is a push plate; 521 is a shoveling section; 522 is a receiving section; 523 is a blocking section; 524 is a discharge port; 530 is a side plate; 540 is a first assembly cavity; 550 is a protective cover; and 560 is a second assembly cavity. 570. Sensor; 580. Light-emitting component; 590. Caster; 591. Buffer strip; 60. Open hopper; 70. Drive assembly; 71. Drive component; 72. Transmission component; 721. Drive wheel; 722. Driven wheel; 723. Synchronous belt; 73. Control component; 80. Screw; 81. Shaft; 82. Double helical blade; 90. Counterweight; 91. Fixing frame; 92. Counterweight plate; 93. Upper shell. Detailed Implementation

[0010] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] Variations in the shapes shown in the accompanying drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the accompanying drawings, but include variations in shape that occur during manufacturing. As used herein, the term “and / or” includes any one of the relevant items listed and any combination of two or more of them.

[0012] Although terms such as “first,” “second,” and “third” may be used herein to describe individual components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts are not limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Therefore, without departing from the teachings of the examples described herein, the first component, assembly, region, layer, or part referred to as the second component, assembly, region, layer, or part may also be referred to as the second component, assembly, region, layer, or part.

[0013] For ease of description, spatial relational terms such as “above,” “upper,” “below,” and “lower” are used herein to describe the relationship between one element and another, as shown in the accompanying drawings. Such spatial relational terms are intended to encompass not only the orientation depicted in the drawings but also different orientations of the device during use or operation. For example, if the device in the drawings is flipped, an element described as being “above” or “upper” relative to another element will subsequently be “below” or “lower” relative to that other element. Therefore, the term “above” includes both “above” and “below” orientations depending on the spatial orientation of the device. The device may also be positioned in other ways, and the spatial relational terms used herein will be interpreted accordingly.

[0014] The terminology used herein is for the purpose of describing various examples only and is not intended to limit the scope of this provision. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms “comprising,” “including,” and “having” enumerate the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0015] The feeding robot provided in this embodiment is applied to modern farms, such as cattle farms, sheep farms, and horse farms. Within the farm, enclosures are divided along both sides of the aisle, and the animals are kept inside. When feeding, the feed is poured outside the enclosures, allowing the animals to stick their heads out to eat.

[0016] like Figure 1 , Figure 2 and Figure 3 As shown in one embodiment of this utility model application, a feeding robot is provided. It includes a mobile platform 10, a first connecting arm 20, a second connecting arm 30, a feeding component 50, a drive assembly 70, and an auger 80. The first connecting arm 20 and the second connecting arm 30 are spaced apart on the mobile platform 10, with the length of the second connecting arm 30 being greater than the length of the first connecting arm 20. The ends of both the first connecting arm 20 and the second connecting arm 30 protrude towards the side of the mobile platform 10. One side of the feeding component 50 is connected to the first connecting arm 20 and the second connecting arm 30, and the other side has an open feed hopper 60. The drive assembly 70 is located on the feeding component 50. The auger 80 is located inside the open feed hopper 60 and is driveably connected to the drive assembly 70. The auger 80 is used to push feed out of the open feed hopper 60.

[0017] The mobile platform 10 provided in this embodiment includes, but is not limited to, various intelligent wheeled or tracked robots with autonomous positioning and navigation capabilities. The mobile platform 10 can autonomously plan its path and achieve automated material pushing through the pusher 50 located on the front side.

[0018] Specifically, two first connecting arms 20 and second connecting arms 30 of different lengths are arranged at intervals (preferably in parallel) on the mobile platform 10, such that the ends of the first connecting arms 20 and the ends of the second connecting arms 30 extend to the front side of the mobile platform 10 and are connected to the back side of the pusher 50. Since the two connecting arms are of different lengths, the pusher 50 connected to the ends of the connecting arms is inclined relative to the mobile platform 10.

[0019] When the mobile platform 10 moves, the pusher 50 scoops up the feed in the forward direction of the mobile platform 10 and concentrates it into the open feed bin 60. The drive component 70 drives the auger 80 in the open feed bin to rotate, pushing the feed in the open feed bin 60 laterally and re-gathering it near the fence so that the animals can eat it.

[0020] In this embodiment, both the pusher 50 and the auger 80 located within the open hopper of the pusher 50 are inclined. Therefore, during the pushing process, the counter-thrust generated by the feed pile is also inclined, i.e., not completely perpendicular to the travel direction of the moving platform 10. Thus, by decomposing the counter-thrust generated by the feed pile, the counter-thrust generated in the direction perpendicular to the travel direction of the moving platform 10 is small, less than the counter-thrust generated when the pusher 50 is laterally positioned on the moving platform 10. This arrangement reduces slippage on the moving platform 10, prevents the robot from deviating from the preset travel path, maintains good pushing performance, reduces the probability of collisions with fences or animals, and improves the reliability and safety of the equipment. Furthermore, the small lateral thrust reduces wear on the robot's power system, extending its service life.

[0021] Preferably, the tilt angle of the pusher 50 relative to the moving platform 10 can be adjusted by changing the difference in length between the first connecting arm 20 and the second connecting arm 30, so that the tilt angle is 10-30 degrees. This 10-30 degree angle range reduces the lateral thrust on the moving platform 10 while preventing excessive tilting from affecting the pushing efficiency of the pusher 50.

[0022] like Figure 2 , Figure 3 and Figure 4 As shown, in another embodiment of this application, the pusher 50 includes a support back plate 510, a push plate 520, and a side plate 530. One side of the support back plate 510 is connected to one side of the first connecting arm 20 and the second connecting arm 30. One side of the push plate 520 is connected to the support back plate 510 away from the first connecting arm 20 and the second connecting arm 30. The other side of the push plate 520 forms the open hopper 60. The side plate 530 is connected to one end of the push plate 520. One end of the auger 80 is disposed on the side plate 530.

[0023] In this embodiment, the support back plate 510 is used to connect the first connecting arm 20 and the second connecting arm 30 and support the push plate 520, transmitting the thrust of the moving platform 10 to the push plate 520 to push the feed on the ground. The push plate 520 is preferably arc-shaped, similar to the shape of a loader bucket, forming a cylindrical open hopper 60 in front of it. During the pushing process, the arc-shaped push plate 520 can smoothly scoop up the feed and gradually transport it upwards, allowing the feed to accumulate quickly and reducing the pressure of pushing.

[0024] In this embodiment, a side plate 530 is provided to assemble the auger 80, allowing the auger 80 to extend along the axial direction of the open hopper 60. This facilitates the rotation of the auger 80 within the open hopper 60, pushing the feed away from the side plate 530 as the auger 80 rotates. Simultaneously, the side plate 530, located on the side of the open hopper 60, also serves to block the feed, preventing it from being squeezed out from the end of the auger 80 during the pushing process, thus preventing the material from further moving away from the enclosure.

[0025] Specifically, the pusher 50 provided in this embodiment can adopt an integrated structure, which integrates the support back plate 510, push plate 520 and side plate 530 to improve the stability of the structure; or it can be manufactured in a split manner, which connects the support back plate 510, push plate 520 and side plate 530 into one piece through fasteners such as bolts, so as to facilitate disassembly and maintenance.

[0026] like Figure 5 As shown, in another embodiment of this application, the pusher plate 520 includes a shoveling section 521, a receiving section 522, and a blocking section 523. The shoveling section 521 is connected to the supporting back plate 510. The bottom surface of the shoveling section 521 is horizontally arranged. The receiving section 522 is connected to the shoveling section 521 and is located above the shoveling section 521. The blocking section 523 is connected to the receiving section 522 and is located above the open hopper 60. The shoveling section 521, the receiving section 522, the blocking section 523, and the side plate 530 together form the open hopper 60.

[0027] In this embodiment, when the pusher plate 520 moves, the bottom surface of the shovel section 521 contacts the ground and is horizontal, which can scoop up the feed on the ground. The feed gradually rises along the shovel section 521 to the receiving section 522, thereby avoiding accumulation in the shovel section 521 and facilitating continuous scooping of feed by the shovel section 521. Specifically, both the shovel section 521 and the receiving section 522 are arc-shaped with the same curvature and are connected sequentially to form an arc-shaped contact surface. At the top of the receiving section 522, the feed falls due to gravity and accumulates in the open hopper 60, so that the auger 80 can push it in a concentrated manner.

[0028] In this embodiment, the material blocking section 523 extends forward along the front end of the material receiving section 522. It can be set as a flat plate and tilted towards the ground. When the auger 80 rotates, the feed thrown out by centrifugal force is blocked by the material blocking section 523 and will not fly out of the open hopper 60. Instead, it continues to return to the open hopper 60 and is eventually pushed out laterally by the auger 80.

[0029] like Figure 5As shown, the pusher plate 520 provided in this embodiment is semi-enclosed, forming an open feed trough with openings at the front and sides, which can quickly concentrate feed and improve the working efficiency of the robot.

[0030] Specifically, as another embodiment of this application, the shoveling section 521, the receiving section 522, and the blocking section 523 are integrally formed. The pusher plate 520 can be integrally formed of metal material to improve the stability of the structure, so as to smoothly push the feed pile and avoid deformation. Specifically, in order to further improve the stability of the structure, reinforcing ribs can also be provided on the surface of the shoveling section 521 or the receiving section 522 facing away from the open hopper 60 to maintain the complete arc shape and achieve the effect of smooth pushing of materials.

[0031] For example Figure 5 As shown in another embodiment of this application, the shovel section 521 has a discharge port 524 at one end opposite to the side plate 530, and the other end of the auger 80 can push feed out from the discharge port 524. The open hopper 60 provided in this embodiment has an opening on the side opposite to the side plate 530, through which the auger 80 can push feed out. Simultaneously, the discharge port 524 provided in this embodiment extends from this opening, causing the rear side of the open hopper 60 to also partially open, allowing the auger 80 to push feed out from the discharge port 524. In other words, by providing the discharge port 524, the efficiency of the auger 80 in pushing feed is further improved, the speed at which feed is delivered from the open hopper 60 is accelerated, feed accumulation is reduced, and the auger 80 is prevented from jamming.

[0032] like Figure 3 and Figure 5 As shown, in another embodiment of this application, a first assembly cavity 540 is formed between the receiving section 522 and the supporting back plate 510; the driving assembly 70 includes a driving member 71 and a transmission member 72, the driving member 71 being disposed within the first assembly cavity 540; the transmission member 72 being disposed on the side plate 530; the input end of the transmission member 72 is connected to the driving member 71, and the output end of the transmission member 72 is connected to the auger 80. Further, a control member 73 is also disposed within the first assembly cavity 540, and the control member 73 is electrically connected to the driving member 71. It should be noted that the control member 73 can also be disposed on the mobile platform 10, and the specific configuration can be flexibly configured according to actual engineering needs.

[0033] In this embodiment, the drive component 70 is used to drive the auger 80 to rotate. The drive component 71 includes, but is not limited to, a motor, and the control component 73 includes, but is not limited to, a printed circuit board. By electrically connecting the drive component 71 and the control component 73 and connecting them to the mobile platform 10, the rotation speed of the auger 80 can be automatically controlled to improve the control of the feeding speed.

[0034] like Figure 6 As shown, the transmission component 72 provided in this embodiment includes a drive wheel 721, a driven wheel 722, and a timing belt 723. The drive wheel 721 is sleeved on the output shaft of the drive component 71, forming the input end of the transmission component 72. The driven wheel 722 is sleeved on the shaft 81 of the auger 80, forming the output end of the transmission component 72. One end of the timing belt 723 is nested on the drive wheel 721, and the other end is nested on the driven wheel 722. Thus, when the drive component 71 provides torque, the transmission component 72 can drive the driven wheel 722 to rotate through the timing belt 723, thereby transmitting torque to the auger 80 and realizing the rotation of the auger 80. In addition, in this embodiment, the drive component 71 and the control component 73 are both assembled in the first assembly cavity 540 to avoid exposure, which can achieve the effect of protecting the drive component 71 and the control component 73. In summary, the drive assembly 70 provided in this embodiment can realize automated control, accurately regulate the speed of the auger 80, and control the efficiency of feed pushing.

[0035] like Figure 7 As shown, in another embodiment of this application, the support back plate 510 includes a mounting plate 40, a connecting plate 511, and a cover plate 512. The connecting plate 511 is connected to the first connecting arm 20 and the second connecting arm 30 through the mounting plate 40, and the connecting plate 511 and the receiving section 522 are combined to form the first assembly cavity 540. One side of the cover plate 512 is detachably connected to the connecting plate 511, and the other side is detachably connected to the receiving section 522. The cover plate 512 is used to cover the first assembly cavity 540.

[0036] In this embodiment, the support back plate 510 is a split design, with the connecting plate 511 serving as a connector and being integrated with the mounting plate 40 via screwing, welding, or other methods. The cover plate 512 can be detachably assembled via screwing, snap-fit, or other methods, allowing the first assembly cavity 540 to be opened at any time for maintenance of the drive component 71 and control component 73 within the first assembly cavity 540.

[0037] For example Figure 2 and Figure 3 As shown, in another embodiment of this application, the pusher 50 includes a protective cover 550, which covers the side plate 530; a second assembly cavity 560 is formed between the protective cover 550 and the side plate 530, and the transmission member 72 is disposed in the second assembly cavity 560. In this embodiment, the drive member 71 is disposed in the first assembly cavity 540, the side plate 530 is attached to the side of the first assembly cavity 540, and a through hole is provided on the side plate 530 to allow the output shaft of the drive member 71 to pass through; the transmission member 72 is disposed on the side of the side plate 530 opposite to the pusher plate 520.

[0038] In this embodiment, the protective cover 550 covers the side plate 530 to cover the transmission components, prevent collisions or dust accumulation, and ensure that the transmission components in the second assembly cavity 560 maintain efficient and stable kinetic energy transmission.

[0039] For example Figure 2 , Figure 3 and Figure 4 As shown, in another embodiment of this application, the pusher 50 is provided to further include a sensor 570 and a light-emitting element 580, the sensor 570 and the light-emitting element 580 being arranged side by side on the top of the stop section 523; and both the sensor 570 and the light-emitting element 580 are electrically connected to the control element 73.

[0040] The sensors 570 provided in this embodiment include, but are not limited to, cameras, infrared sensors, and ultrasonic sensors. The sensors 570 monitor the environment in front of the open silo 60. When an obstacle is encountered in front, a signal is sent to the control unit 73 in a timely manner so that the mobile platform 10 can stop moving in time or adjust its travel route to avoid collision.

[0041] For example, when the robot moves too close to the fence, the front of the open hopper 60 may hit the animal's head. If it continues to move, the auger 80 may injure the animal and cause unnecessary losses. Early warning through the sensor 570 can improve the safety of robot use.

[0042] The light-emitting element 580 provided in this embodiment is used to increase the brightness in front of the open hopper 60 for easier observation. For example, when the sensor 570 is a camera, the light-emitting element 580 is set as a supplementary light, which illuminates the ground in front of the push plate 520, making the environmental image within the camera's detection range clearer and facilitating timely identification of obstacles.

[0043] For example Figure 3 and Figure 4 As shown, in another embodiment of this application, the pusher 50 is provided to include casters 590, which are located on the side away from the open hopper 60; and the bottom end of the casters 590 is flush with the bottom end of the pusher plate 520.

[0044] In this embodiment, the robot may encounter slopes or bumps on the ground during movement. By providing casters 590, the robot's mobility is improved. When the terrain changes, the casters 590 promptly raise the push plate 520, preventing the push plate 520 from scooping up soil or stones, reducing wear on the push plate 520 and the auger 80, and preventing damage to the ground. Furthermore, the casters 590 are located on the side away from the open feed hopper 60 to prevent them from getting tangled in feed such as hay and jamming.

[0045] For example Figure 3 and Figure 4 As shown in another embodiment of this application, a buffer strip 591 is provided at the front end of the push plate 520. In this embodiment, the buffer strip 591 is a strip made of soft materials such as rubber or latex, and is fixed to the front end of the push plate 520 by means of bonding, snap-fitting, or screwing. In the event of an accidental collision, the buffer strip 591 acts as a buffer, protecting the push plate 520.

[0046] like Figure 8 As shown, in another embodiment of this application, the auger 80 is provided as a double-helix auger, consisting of a shaft 81 and double-helix blades 82 wound around the shaft 81. By setting the double-helix blades 82, two blades participate in pushing the feed with each revolution, thus achieving a higher filling rate and a conveying capacity that is generally greater than that of a single-head auger of the same specification, improving the efficiency of pushing feed. Moreover, the two blades alternately and continuously push the feed, making the movement of the feed more continuous and stable, reducing pulsating flow, contributing to uniform discharge, and reducing sudden side slippage problems.

[0047] For example Figure 1 and Figure 2 As shown, in another embodiment of this application, the pushing robot further includes a counterweight 90, which is detachably mounted on the mobile platform 10. In this embodiment, the pushing component 50, drive assembly 70, auger 80, and other components are all located at the front of the mobile platform 10, which can easily cause the robot's center of gravity to shift forward. Since the robot's drive wheels are all mounted on the mobile platform 10, assembling a counterweight on the mobile platform 10 adjusts the robot's center of gravity, preventing excessive forward tilting and maintaining the robot's stability.

[0048] Furthermore, such as Figure 9 As shown, the counterweight 90 provided in this embodiment can be composed of a fixing frame 91, a counterweight plate 92, and an upper shell 93. The fixing frame 91 is fixed to the moving platform 10 by welding or screwing, and is preferably set on both sides of the first connecting arm 20 and the second connecting arm 30. Multiple counterweight plates 92 can be provided in this embodiment. An appropriate number of counterweight plates 92 are selected according to the actual need for counterweight and stacked on the fixing frame 91 to press down the rear half of the first connecting arm 20 and the second connecting arm 30 to achieve balance. The upper shell 93 covers the moving platform 10, covering the counterweight plate 92 and playing a protective role.

[0049] In summary, this application provides a feeding robot, comprising a mobile platform 10, a first connecting arm 20, a second connecting arm 30, a feeding component 50, a drive assembly 70, and an auger 80. The first connecting arm 20 and the second connecting arm 30 are arranged parallel to each other on the mobile platform 10, and the length of the second connecting arm 30 is greater than the length of the first connecting arm 20. Furthermore, the ends of the first connecting arm 20 and the second connecting arm 30 both protrude towards the side of the mobile platform 10 to jointly connect and support the feeding component 50. An open feed bin 60 is provided on the other side of the feeding component 50. The drive assembly 70 is disposed on the feeding component 50. The auger 80 is connected to the feeding component 50 and disposed within the open feed bin 60. Furthermore, the auger 80 is drive-connected to the drive assembly 70 and is used to push feed out of the open feed bin 60.

[0050] The feeding robot provided in this embodiment uses a first connecting arm 20 and a second connecting arm 30 of different lengths on a mobile platform 10. The feeding component 50 located at the ends of the first connecting arm 20 and the second connecting arm 30 is tilted. When the mobile platform 10 moves, the feeding component 50 concentrates the feed in the forward direction of the mobile platform 10 into the open feed bin 60. An auger 80 is installed on the feeding component 50. Driven by the drive assembly 70, the auger 80 rotates, pushing the feed in the open feed bin 60 laterally and re-gathering it near the fence for easy access by animals. Because the auger 80 is tilted, the counterforce generated by the feed pile during feeding is also tilted, rather than completely perpendicular to the direction of travel of the mobile platform 10. Therefore, the mobile platform 10 can reduce slippage during travel, avoid deviating from its path, reduce the probability of collisions with fences or animals, and improve the reliability and safety of the equipment.

[0051] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0052] It should be noted that this utility model uses a pusher robot as an example to introduce the specific structure and working principle of this utility model, but the application of this utility model is not limited to pusher robots, and can also be applied to the production and use of other similar workpieces.

[0053] It should be understood that this invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this invention is limited only by the appended claims.

[0054] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Images