A three-wheel tennis ball serving machine with side-rotating inner oscillation

Abstract

The utility model discloses a three -wheel tennis ball -serving machine with side -rotating internal oscillation, the machine group fixing frame of three -wheel type ball -serving device is connected with the bottom plate of shell through the positioning pivot, three motor frame includes three ball -serving wheel fixed frame that mutually show 120 DEG, the wheel surface of three ball -serving wheels mutually show 120 DEG and form the ball -serving gap in the middle, and the direction of first ball -serving wheel is vertical direction. The front side wall of shell is equipped with the ball outlet, and the ball outlet is rectangle, and the ball outlet corresponds first ball -serving wheel, and the ball -serving gap between second ball -serving wheel and third ball -serving wheel front. Three -wheel type ball -serving device cooperation height adjusting device and horizontal adjusting device can adjust the angle height and left and right direction of the ball outlet, can send topspin, underspin or side -spin ball according to the training requirement, and ball -serving device and adjusting device are all arranged in the shell inside, and the height and angle of the ball that user can not predict when using, better improvement training efficiency.

Description

Technical Field

[0001] This utility model relates to the field of sports assistive equipment technology, specifically a tennis ball serving machine with a three-wheeled ball serving machine that can rotate laterally and oscillate internally. Background Technology

[0002] The existing tennis ball serving machines mainly have the following serving principles: (1) Two-wheel ball serving machine, two high-speed rotating wheels in opposite directions, the space between the wheels is slightly smaller than the diameter of the ball, when the ball rolls from the slide rail into the space between the two wheels, the friction between the wheels and the ball will quickly spin the ball out; (2) Spring ball serving machine, the power source compresses the spring, when the spring stores enough potential energy, the spring is released, the tennis ball gains a certain initial energy under the action of the spring potential energy, and then the ball is launched out; (3) Pneumatic ball serving machine, the air pressure generated by the air compressor is stored in the gas collecting cylinder, when the ball falls into the ball feeding tube, the gas in the cylinder is released, and the ball is launched out by the gas pressure; (4) Catapult ball serving machine, the elasticity of the steel plate is used to launch the ball out.

[0003] However, existing tennis ball serving machines generally have some shortcomings. For example, the internal structure of the machine often cannot adjust the height and lateral direction of the ball, resulting in a poor user experience. Furthermore, the machine's design cannot integrate the tennis ball and racket, requiring users to carry them separately for training, which is inconvenient.

[0004] Therefore, there is a need to provide a tennis ball serving machine with a three-wheeled ball serving machine that can generate topspin, backspin, and sidespin balls by using three serving wheels in three directions and operating under the control of three brushless motors. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide a three-wheel tennis ball serving machine with side-spin internal oscillation. The three-wheel serving device, together with the height adjustment device and the horizontal adjustment device, can adjust the speed, angle, height, and left and right direction of the ball, thereby improving training efficiency.

[0006] A three-wheel tennis ball serving machine with side-spin internal oscillation includes a housing and a three-wheel serving device disposed within the housing. The three-wheel serving device includes a machine unit mounting frame, a positioning shaft, a three-motor frame, a first serving wheel, a first serving wheel motor, a second serving wheel, a second serving wheel motor, a third serving wheel, and a third serving wheel motor. The machine unit mounting frame is connected to the bottom plate of the housing via the positioning shaft. A three-motor frame shaft is provided on one side of the three-motor frame. The machine unit mounting frame has positioning holes corresponding to the positions of the three-motor frame shafts. The three-motor frame shafts are rotatably disposed within the positioning holes.

[0007] The three-motor frame includes three serving wheel fixing frames that are 120° apart. Adjacent serving wheel fixing frames are connected by a connecting plate. The first serving wheel motor, the second serving wheel motor, and the third serving wheel motor are respectively located on the outside of the corresponding serving wheel fixing frames. The first serving wheel, the second serving wheel, and the third serving wheel are all located on the inside of the corresponding serving wheel fixing frames, and their central rotation axes are respectively connected to the output ends of the first serving wheel motor, the second serving wheel motor, and the third serving wheel motor. The wheel surfaces of the first serving wheel, the second serving wheel, and the third serving wheel are 120° apart and form a serving gap in the middle. The direction of the first serving wheel is vertical.

[0008] The front sidewall of the outer shell is provided with a ball outlet, which is rectangular and corresponds to the front of the service gap between the first service wheel, the second service wheel and the third service wheel.

[0009] Furthermore, the top of the outer shell is provided with a ball container, the bottom of the ball container is provided with a ball feeding turntable, the center of the ball feeding turntable is provided with a ball feeding shaft, the bottom end of the ball feeding shaft is connected to a turntable motor, the top of the ball feeding shaft is evenly distributed with partitions, and the bottom of the ball feeding turntable is provided with a ball leakage hole. The three-wheeled ball serving device is located below the ball leakage hole. The design of the ball feeding turntable, the ball feeding shaft, and the partitions achieves the function of distributing the ball while simultaneously guiding it, ensuring that no ball gets stuck in the ball container. The tennis ball rotates counterclockwise in the ball feeding turntable via the ball feeding shaft and partitions controlled by the turntable motor. The four partitions on the ball feeding turntable guide the tennis ball in the ball container, causing it to rotate and fall through the ball leakage hole.

[0010] Furthermore, a guide groove is provided below the ball-draining hole, with the bottom end of the guide groove close to the back of the service gap between the first, second, and third service wheels. The tennis ball falling from the ball-draining hole passes through the guide groove to the back of the service gap between the first, second, and third service wheels, and is then propelled out by the opposing rotation of the first, second, and third service wheels through a squeezing motion.

[0011] Furthermore, the tennis ball serving machine includes a height adjustment device, which comprises a height adjustment stepper motor and a height adjustment lever. The height adjustment stepper motor is fixedly mounted at the bottom of the unit mounting frame behind the three-motor frame. The output end of the height adjustment stepper motor is connected to one end of the height adjustment lever, and the other end of the height adjustment lever is connected to the bottom connecting plate of the three-motor frame via a fixed rotating shaft. The height adjustment stepper motor controls the height adjustment lever, causing a change in the tilt angle of the three-motor frame, thereby changing the overall tilt angle of the first, second, and third serving wheels, and adjusting the height of the ball launch angle.

[0012] Furthermore, the tennis ball serving machine also includes a horizontal adjustment device, which includes a horizontal adjustment stepper motor, a horizontal vibration plate, and a horizontal adjustment shaft. The bottom of the machine unit fixing frame is rotatably mounted on the bottom plate of the outer casing via a positioning shaft. The bottom plate has an elongated hole. The horizontal adjustment stepper motor is fixedly mounted on the upper surface of the bottom wall of the machine unit fixing frame. The output end of the horizontal adjustment stepper motor passes through the bottom wall of the machine unit fixing frame and is connected to one end of the horizontal vibration plate. The other end of the horizontal vibration plate is connected to the horizontal adjustment shaft. The bottom end of the horizontal adjustment shaft is located in the elongated hole.

[0013] The horizontal adjustment stepper motor controls the horizontal oscillating plate to swing left and right around the center of the elongated hole, which drives the horizontal adjustment shaft to swing left and right synchronously. Since the bottom end of the horizontal adjustment shaft is inside the elongated hole, the entire unit's fixed frame rotates left and right around the positioning shaft within the rotatable range of the horizontal adjustment stepper motor under the action of the torque of the elongated hole.

[0014] Furthermore, the bottom of the base plate is equipped with shock-absorbing feet, which are fixed to the ground. Because the shock-absorbing feet are fixed to the ground, the base plate remains stationary. The mounting bracket on the base plate can swing horizontally left and right, thereby adjusting the left and right direction of the ball release. This achieves an internally vibrating ball-serving device. Since the ball-serving device is located inside the outer casing, the user cannot predict the height and angle of the ball release, improving training efficiency. Simultaneously, the shock-absorbing feet reduce the impact of vibrations during the ball-serving machine's operation.

[0015] Furthermore, the first, second, and third serve wheel motors are all brushless motors. The output direction of the first serve wheel motor is opposite to that of the second and third serve wheel motors. The rotation direction of the first, second, and third serve wheels at the serve gap is the same as the ball release direction. The serve speed and feed frequency are controlled by the machine's built-in main controller. Users can connect to the machine via Bluetooth using a mobile phone or handheld device and use the corresponding app to adjust and control the serve speed and direction. This optimized design also ensures that the serve machine can produce any programmed tennis ball.

[0016] Furthermore, the top of the outer casing is equipped with a ball-blocking flap, which is connected to the top of the side wall of the outer casing via a hinge. The ball-blocking flap can create a larger receiving space above the ball container, accommodating more tennis balls and improving the efficiency of the ball serving machine.

[0017] Furthermore, a telescopic rod is provided on the rear side wall of the housing, and casters are provided on the bottom of the housing. The telescopic rod and casters facilitate the user's movement of the tennis ball serving machine.

[0018] The beneficial effects of this utility model are as follows:

[0019] This utility model discloses a three-wheeled tennis ball serving machine with side-spin internal oscillation. By employing the above-mentioned technical solutions, the three-wheeled serving device, combined with height and level adjustment devices, allows for adjustment of the ball's angle (height and lateral direction). It can serve topspin, backspin, or sidespin balls according to training requirements. Furthermore, since the serving device and adjustment devices are all located inside the outer casing, the user cannot predict the ball's height and angle, thus improving training efficiency. The serving speed and ball feeding frequency are controlled by the machine's built-in main controller. This optimized design also ensures that the machine can serve any programmed tennis ball.

[0020] The above description is only an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of this utility model easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0021] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0022] Figure 1 This diagram shows the overall structure of a three-wheeled tennis ball serving machine with side-spin internal oscillation according to the present invention.

[0023] Figure 2 This diagram shows the outer shell structure of a three-wheeled tennis ball serving machine with side-spin internal oscillation according to the present invention.

[0024] Figure 3 This diagram shows a ball bucket structure of a three-wheeled tennis ball serving machine with side-spinning internal oscillation according to the present invention.

[0025] Figure 4 This diagram shows the base plate and the three-wheeled serving device of a tennis ball serving machine with side-spin internal oscillation according to the present invention.

[0026] Figure 5 This diagram shows a height adjustment device for a three-wheeled tennis ball serving machine with side-spin internal oscillation according to the present invention.

[0027] Figure 6 This diagram shows a horizontal adjustment device for a three-wheeled tennis ball serving machine with side-spinning internal oscillation according to the present invention.

[0028] Explanation of main figure symbols

[0029] 1-Outer shell, 2-Ball-blocking flap, 3-Hinge, 4-Ball outlet, 5-Telescopic rod, 6-Drag wheel, 7-Shock-absorbing foot, 8-Ball bucket, 9-Ball feeding turntable, 10-Baffle plate, 11-Ball leakage hole, 12-Turntable motor, 13-Guide groove, 14-Three-motor frame, 15-First ball-serving wheel, 16-Second ball-serving wheel, 17-Third ball-serving wheel, 18-Three-motor frame shaft, 19-First ball-serving wheel motor, 20-Second ball-serving wheel motor, 21-Third ball-serving wheel motor, 22-Height adjustment lever, 23-Height adjustment stepper motor, 24-Horizontal adjustment stepper motor, 25-Horizontal vibration plate, 26-Horizontal adjustment shaft, 27-Base plate, 28-Oblong hole, 29-Positioning shaft, 30-Unit fixing frame. Detailed Implementation

[0030] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. However, it should be understood that the scope of protection of this utility model is not limited to the specific embodiments.

[0031] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0032] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “up,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An object may also have other orientations (rotated 90 degrees or other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0033] like Figures 1-6 As shown, a three-wheeled tennis ball serving machine with side-spin internal oscillation includes a housing 1 and a three-wheeled ball serving device disposed within the housing 1.

[0034] The top of the outer casing 1 is provided with a ball container 8, the bottom of the ball container 8 is provided with a ball feeding turntable 9, the center of the ball feeding turntable 9 is provided with a ball feeding shaft, the bottom end of the ball feeding shaft is connected to a turntable motor 12, the top end of the ball feeding shaft is provided with evenly distributed partitions 10, and the bottom of the ball feeding turntable 9 is provided with a ball leakage hole 11. The three-wheeled ball serving device is located below the ball leakage hole 11. The design of the ball feeding turntable 9, the ball feeding shaft, and the partitions 10 achieves the function of distributing the ball while simultaneously guiding it, ensuring that no ball gets stuck in the ball container 8. The tennis ball rotates counterclockwise in the ball feeding turntable 9 through the ball feeding shaft and partitions 10 controlled by the turntable motor 12. The four partitions 10 on the ball feeding turntable 9 guide the tennis ball in the ball container 8, causing it to rotate and fall through the ball leakage hole 11.

[0035] The three-wheeled serving device includes a unit mounting frame 30, a positioning shaft 29, a three-motor frame 14, a first serving wheel 15, a first serving wheel motor 19, a second serving wheel 16, a second serving wheel motor 20, a third serving wheel 17, and a third serving wheel motor 21. The unit mounting frame 30 is connected to the bottom plate 27 of the outer casing 1 via the positioning shaft 29. A three-motor frame shaft 18 is provided on one side of the three-motor frame 14. The unit mounting frame 30 is provided with positioning holes corresponding to the positions of the three-motor frame shaft 18. The three-motor frame shaft 18 is rotatably mounted in the positioning holes.

[0036] The three-motor frame 14 includes three serving wheel fixing frames that are 120° apart. Adjacent serving wheel fixing frames are connected by a connecting plate. The first serving wheel motor 19, the second serving wheel motor 20, and the third serving wheel motor 21 are respectively located on the outer side of the corresponding serving wheel fixing frame. The first serving wheel 15, the second serving wheel 16, and the third serving wheel 17 are all located on the inner side of the corresponding serving wheel fixing frame, and their central rotation axes are respectively connected to the output ends of the first serving wheel motor 19, the second serving wheel motor 20, and the third serving wheel motor 21. The wheel surfaces of the first serving wheel 15, the second serving wheel 16, and the third serving wheel 17 are 120° apart and form a serving gap in the middle. The direction of the first serving wheel 15 is vertical.

[0037] Below the ball-feeding hole 11, a guide groove 13 is provided. The bottom end of the guide groove 13 is close to the back of the service gap between the first service wheel 15, the second service wheel 16, and the third service wheel 17. The tennis ball falling from the ball-feeding hole 11 passes through the guide groove 13 and falls behind the service gap between the first service wheel 15, the second service wheel 16, and the third service wheel 17. The tennis ball is then launched by squeezing as the first service wheel 15, the second service wheel 16, and the third service wheel 17 rotate in opposite directions.

[0038] The front sidewall of the outer shell 1 is provided with a ball outlet 4, which is rectangular and corresponds to the front of the service gap between the first service wheel 15, the second service wheel 16 and the third service wheel 17.

[0039] The tennis ball serving machine includes a height adjustment device, which comprises a height adjustment stepper motor 23 and a height adjustment lever 22. The height adjustment stepper motor 23 is fixedly mounted at the bottom of the unit mounting frame 30 behind the three-motor frame 14. The output end of the height adjustment stepper motor 23 is connected to one end of the height adjustment lever 22, and the other end of the height adjustment lever 22 is connected to the bottom connecting plate of the three-motor frame 14 via a fixed rotating shaft. The height adjustment stepper motor 23 controls the height adjustment lever 22 to change the tilt angle of the three-motor frame 14, thereby changing the overall tilt angle of the first serving wheel 15, the second serving wheel 16, and the third serving wheel 17, and adjusting the height of the ball launch angle.

[0040] The tennis ball serving machine also includes a horizontal adjustment device, which includes a horizontal adjustment stepper motor 24, a horizontal vibration plate 25, and a horizontal adjustment shaft 26. The bottom of the machine unit mounting frame 30 is rotatably mounted on the bottom plate 27 of the bottom of the outer casing 1 via a positioning shaft 29. The bottom plate 27 is provided with an elongated hole 28. The horizontal adjustment stepper motor 24 is fixedly mounted on the upper surface of the bottom wall of the machine unit mounting frame 30. The output end of the horizontal adjustment stepper motor 24 passes through the bottom wall of the machine unit mounting frame 30 and is connected to one end of the horizontal vibration plate 25. The other end of the horizontal vibration plate 25 is connected to the horizontal adjustment shaft 26. The bottom end of the horizontal adjustment shaft 26 is located in the elongated hole 28.

[0041] The horizontal adjustment stepper motor 24 controls the horizontal oscillating plate 25 to swing left and right around the center of the elongated hole 28, which drives the horizontal adjustment shaft 26 to swing left and right synchronously. Since the bottom end of the horizontal adjustment shaft 26 is inside the elongated hole 28, the entire unit fixing frame 30 rotates left and right around the positioning shaft 29 within the rotatable range of the horizontal adjustment stepper motor 24 under the action of the torque of the elongated hole 28.

[0042] The bottom of the base plate 27 is equipped with shock-absorbing feet 7, which are fixed to the ground. Because the shock-absorbing feet 7 are fixed to the ground, the base plate 27 remains stationary. The machine mounting bracket 30 can swing horizontally left and right on the base plate 27, thereby adjusting the left and right direction of the ball release. This achieves an internally vibrating ball-serving device. Since the ball-serving device is located inside the outer casing, the user cannot predict the height and angle of the ball release, improving training efficiency. Simultaneously, the shock-absorbing feet 7 reduce the impact of vibration on the ball-serving machine during operation.

[0043] The first serve wheel motor 19, the second serve wheel motor 20, and the third serve wheel motor 21 are all brushless motors. The output direction of the first serve wheel motor 19 is opposite to that of the second serve wheel motor 20 and the third serve wheel motor 21. The rotation direction of the first serve wheel 15, the second serve wheel 16, and the third serve wheel 17 at the serve gap is the same as the ball release direction. The serve speed and feed frequency are controlled by the machine's built-in main controller. A mobile phone or handheld device can be connected to the machine via Bluetooth, and the corresponding APP can be used to adjust and control the serve speed and serve direction. The optimized design also ensures that the serve machine can produce any programmed tennis ball.

[0044] The top of the outer casing 1 is provided with a ball-blocking flap 2, which is connected to the top of the side wall of the outer casing 1 via a hinge 3. The ball-blocking flap 2 can create a larger holding space above the ball container 8, accommodating more tennis balls and improving the efficiency of the ball serving machine.

[0045] A telescopic rod 5 is provided on the rear side wall of the outer casing 1, and a caster wheel 6 is provided on the bottom of the outer casing 1. The telescopic rod 5 and the caster wheel 6 facilitate the user's movement of the tennis ball serving machine.

[0046] The working process of this utility model's three-wheel side-spin ball internal oscillation tennis ball serving machine is as follows:

[0047] First, turn on the power button. The turntable motor 12 drives the ball feeding shaft and the partition 10 to rotate counterclockwise on the ball feeding turntable 9. The four partitions 10 move the tennis balls in the ball bucket 8, causing the tennis balls to rotate and pass through the ball leakage hole 11, fall into the guide groove 13, and fall down the guide groove 13 to the back of the service gap between the first service wheel 15, the second service wheel 16, and the third service wheel 17.

[0048] The output of the horizontal adjustment stepper motor 24 drives the horizontal oscillation plate 25 to rotate left and right around its connection point with the horizontal adjustment stepper motor 24. The horizontal adjustment shaft 26, fixed at the other end of the horizontal oscillation plate 25, is driven to swing left and right in an arc. Since the horizontal adjustment shaft 26 is inside the elongated hole 28 of the base plate 27, the base plate 27 will rotate relative to the unit mounting frame 30 under its torque. Since the shock-absorbing feet 7 at the bottom of the base plate 27 are fixed to the ground and will not rotate, the unit mounting frame 30 will swing left and right in the horizontal direction, thereby adjusting the left and right angle of the ball output. At the same time, the height adjustment stepper motor 23 starts to work, and adjusts the tilt angle of the three-motor frame 14 through the height adjustment lever 22, thereby adjusting the height angle of the ball output.

[0049] While the height and level adjustment devices are operating, the first serve wheel motor 19, the second serve wheel motor 20, and the third serve wheel motor 21 control the first serve wheel 15, the second serve wheel 16, and the third serve wheel 17 to start working and control their rotation speed, thereby controlling the serve speed. The tennis ball falling into the guide groove 13 is propelled by the opposing rotation of the first serve wheel 15, the second serve wheel 16, and the third serve wheel 17, launching the ball from between the three serve wheels through a squeezing motion, thus achieving the requirement of serving topspin, backspin, and sidespin balls with different speeds and spin directions.

[0050] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the present invention to the precise forms described, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the present invention and its practical applications, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the present invention, as well as various different choices and variations. Any simple modifications, equivalent changes, and alterations made to the foregoing exemplary embodiments should fall within the protection scope of the present invention.

Claims

1. A three-wheeled tennis ball server with side-rotating inner oscillation, characterized in that: Includes a housing (1) and a three-wheeled ball-serving device disposed within the housing (1); The three-wheeled ball-serving device includes a unit mounting frame (30), a positioning shaft (29), a three-motor frame (14), a first ball-serving wheel (15), a first ball-serving wheel motor (19), a second ball-serving wheel (16), a second ball-serving wheel motor (20), a third ball-serving wheel (17), and a third ball-serving wheel motor (21). The unit mounting frame (30) is connected to the bottom plate (27) of the outer shell (1) through the positioning shaft (29). A three-motor frame rotating shaft (18) is provided on one side of the three-motor frame (14). The unit mounting frame (30) is provided with a positioning hole corresponding to the position of the three-motor frame rotating shaft (18). The three-motor frame rotating shaft (18) is rotatably installed in the positioning hole. The three-motor frame (14) includes three serving wheel fixing frames that are 120° apart. Adjacent serving wheel fixing frames are connected by a connecting plate. The first serving wheel motor (19), the second serving wheel motor (20), and the third serving wheel motor (21) are respectively located on the outside of the corresponding serving wheel fixing frames. The first serving wheel (15), the second serving wheel (16), and the third serving wheel (17) are all located on the inside of the corresponding serving wheel fixing frames, and their central rotation axes are respectively connected to the output ends of the first serving wheel motor (19), the second serving wheel motor (20), and the third serving wheel motor (21). The wheel surfaces of the first serving wheel (15), the second serving wheel (16), and the third serving wheel (17) are 120° apart and a serving gap is formed in the middle. The direction of the first serving wheel (15) is vertical. The front side wall of the outer shell (1) is provided with a ball outlet (4), which is rectangular and corresponds to the front of the service gap between the first service wheel (15), the second service wheel (16) and the third service wheel (17).

2. A three-wheeled tennis ball server with side-rotatable inner oscillation according to claim 1, characterized in that: The top of the outer shell (1) is provided with a ball bucket (8), the bottom of the ball bucket (8) is provided with a ball feeding turntable (9), the center of the ball feeding turntable (9) is provided with a ball feeding shaft, the bottom end of the ball feeding shaft is connected to a turntable motor (12), the top of the ball feeding shaft is evenly provided with partitions (10), the bottom of the ball feeding turntable (9) is provided with a ball leakage hole (11), and the three-wheel ball serving device is located below the ball leakage hole (11).

3. A three-wheeled tennis ball server with side-rotatable inner oscillation according to claim 2, characterized in that: Below the ball-leaking hole (11) is a guide groove (13), the bottom end of which is close to the first serving wheel (15), behind the serving gap between the second serving wheel (16) and the third serving wheel (17).

4. A three-wheeled tennis ball server with side-rotatable inner oscillation according to claim 3, characterized in that: The tennis ball serving machine includes a height adjustment device, which includes a height adjustment stepper motor (23) and a height adjustment lever (22). The height adjustment stepper motor (23) is fixedly installed at the bottom of the unit fixing frame (30) behind the three-motor frame (14). The output end of the height adjustment stepper motor (23) is connected to one end of the height adjustment lever (22), and the other end of the height adjustment lever (22) is connected to the bottom connecting plate of the three-motor frame (14) through a fixed rotating shaft.

5. A three-wheeled tennis ball server with side-rotatable inner oscillation according to claim 4, characterized in that: The tennis ball serving machine also includes a horizontal adjustment device, which includes a horizontal adjustment stepper motor (24), a horizontal vibration plate (25), and a horizontal adjustment shaft (26). The bottom of the machine unit fixing frame (30) is rotatably mounted on the bottom plate (27) of the bottom of the outer shell (1) via a positioning shaft (29). The bottom plate (27) is provided with an elongated hole (28). The horizontal adjustment stepper motor (24) is fixedly mounted on the upper surface of the bottom wall of the machine unit fixing frame (30). The output end of the horizontal adjustment stepper motor (24) passes through the bottom wall of the machine unit fixing frame (30) and is connected to one end of the horizontal vibration plate (25). The other end of the horizontal vibration plate (25) is connected to the horizontal adjustment shaft (26). The bottom end of the horizontal adjustment shaft (26) is located in the elongated hole (28).

6. A three-wheeled tennis ball server with side-rotatable inner oscillation according to claim 5, characterized in that: The bottom of the base plate (27) is provided with shock-absorbing feet (7), which are fixed to the ground.

7. A three-wheeled tennis ball server with side-rotatable inner oscillation according to claim 1, characterized in that: The first serving wheel motor (19), the second serving wheel motor (20) and the third serving wheel motor (21) are all brushless motors. The output direction of the first serving wheel motor (19) is opposite to the output direction of the second serving wheel motor (20) and the third serving wheel motor (21). The rotation direction of the first serving wheel (15), the second serving wheel (16) and the third serving wheel (17) at the serving gap is consistent with the ball release direction.

8. A three-wheeled tennis ball server with side-rotating inner oscillation according to claim 1, characterized in that: The top of the outer shell (1) is provided with a ball-blocking flap (2), which is connected to the top of the side wall of the outer shell (1) via a hinge (3).

9. A three-wheeled tennis ball server with side-rotating inner oscillation according to claim 1, characterized in that: The rear side wall of the outer casing (1) is provided with a telescopic rod (5), and the bottom of the outer casing (1) is provided with a tow wheel (6).

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