Electric front and back adjusting headrest mechanism for car seat

Abstract

The utility model relates to the technical field of automobile mechanical equipment, concretely relates to a kind of electric front and rear adjusting headrest mechanism of automobile seat, including, middle shell mechanism assembly, including middle shell and two headrest rods in the middle shell being arranged;Shell assembly is movably sleeved on the outside of middle shell along front and rear direction, and the bottom of shell assembly is equipped with opening;Adjusting drive assembly, including, screw rod nut cylinder, it is arranged in middle shell, and its axis extends along front and rear direction;Motor screw rod, rotationally arranged in shell assembly and with screw rod nut cylinder coaxial screw connection;Motor, it is arranged in the inner wall of shell assembly, and its output shaft is connected with motor screw rod transmission;By the transmission mechanism is completely integrated in headrest interior, adopt screw rod nut transmission cooperation sliding guide structure, realize compact structure design, solve the problem that electric headrest adjusting mechanism in the prior art is arranged in seat backrest and occupies space, influence other functional mechanism arrangement, or headrest mechanism is complex, bulky, poor applicability.

Description

Technical Field

[0001] This utility model relates to the field of automotive mechanical equipment technology, specifically to an electric fore-and-aft adjustable headrest mechanism for automotive seats. Background Technology

[0002] With the rapid development of the national economy and the continuous improvement of people's living standards, the pursuit of a comfortable and convenient life has led to the increasing popularity of automobiles. People who pursue a high-quality life are increasingly looking forward to the user-friendly and convenient design of automobile functions.

[0003] As the component of a car that passengers come into contact with most frequently, car seats directly affect passenger comfort. Headrests provide good head support, and different passengers have different needs regarding the fore-and-aft position of the headrest at different times. The gap between the passenger's head and the headrest also affects the seat's safety performance. However, very few car seat headrests on the market currently have electric fore-and-aft adjustment capabilities.

[0004] Currently, most commonly used electric headrest adjustment mechanisms for car seats are located inside the seat back, occupying internal space and affecting the arrangement of ventilation and massage mechanisms, or the headrest mechanism is complex and takes up a lot of space. To solve these problems, the electric adjustment mechanism of this utility model is completely integrated inside the headrest. This mechanism has a compact structure, occupies little space, is lightweight, and has strong applicability. Utility Model Content

[0005] To address the problems existing in the prior art, an electric fore-and-aft adjustable headrest mechanism for automobile seats is provided. By fully integrating the transmission mechanism (including the middle shell mechanism assembly, the rear cover motor assembly, and the adjustment drive component) inside the headrest, and using a screw and nut transmission combined with a sliding guide structure, a compact design is achieved. This solves the problems of existing electric headrest adjustment mechanisms being mostly located inside the seat back, occupying space and affecting the arrangement of other functional mechanisms, or having complex, large, and poorly applicable headrest mechanisms.

[0006] To address the problems of existing technologies, this utility model provides an electric fore-and-aft adjustable headrest mechanism for automobile seats, comprising: a middle shell assembly, including a middle shell and two headrest rods vertically disposed within the middle shell; an outer shell assembly, movably sleeved on the outside of the middle shell in a front-to-back direction, the bottom of the outer shell assembly having an opening extending in a front-to-back direction through which the headrest rods pass; an adjustment drive assembly, including a lead screw and nut sleeve disposed within the middle shell, with its axis extending in a front-to-back direction; a motor lead screw rotatably disposed within the outer shell assembly and coaxially threadedly connected to the lead screw and nut sleeve; and a motor disposed on the inner wall of the outer shell assembly, its output shaft being drively connected to the motor lead screw; wherein, when the motor drives the motor lead screw to rotate, the threaded engagement between the motor lead screw and the lead screw and nut sleeve causes the outer shell assembly to move relative to the middle shell assembly in a front-to-back direction.

[0007] Preferably, the outer shell assembly includes a front cover and a rear cover of the headrest. The front cover of the headrest is provided with mounting buckles on its periphery, and the rear cover of the headrest is provided with buckle grooves on its periphery. The mounting buckles are connected to the buckle grooves, and the motor is located inside the rear cover of the headrest.

[0008] Preferably, the middle shell is provided with guide sleeve mounting grooves on both sides along its width direction. The middle shell assembly also includes two headrest rod guide sleeves, which are respectively inserted into the guide sleeve mounting grooves of the middle shell, and the two headrest rods are respectively inserted into the two headrest rod guide sleeves.

[0009] Preferably, the headrest back cover is provided with rear positioning posts on both sides, and the middle shell is provided with rear positioning holes coupled to the rear positioning posts.

[0010] Preferably, the front cover of the headrest is provided with front positioning posts on both sides, and the front positioning posts are inserted into and engaged with the rear positioning posts.

[0011] Preferably, the headrest rod is provided with a headrest rod groove that connects to the backrest guide tube, and the headrest rod is hollow and used for the power supply line to pass through and connect to the backrest wiring harness.

[0012] Preferably, the bottom end of the middle shell is provided with a longitudinal limiting groove, and the middle shell assembly also includes a headrest rod connecting plate. The lower end of the headrest rod connecting plate is provided with two limiting sheet metal pieces, which are inserted into the two longitudinal limiting grooves of the middle shell. The two sides of the headrest rod connecting plate are fixedly connected to two headrest rods.

[0013] Preferably, the headrest back cover is provided with guide rails on both sides, and the middle shell is also provided with middle shell slide rail claws coupled with the guide rails to achieve front and rear sliding connection with the middle shell mechanism assembly.

[0014] Preferably, the front cover of the headrest is provided with inner guide rails on both sides, the inner guide rails slide in conjunction with the outer guide rails, and the front cover of the headrest and the back cover of the headrest are fixedly connected by bolts.

[0015] Preferably, after the motor is powered on, the motor lead screw rotates inside the lead screw nut sleeve, which is fixed to the middle shell and the headrest rod. The rotation of the lead screw drives the motor and the front and rear covers of the headrest that are fixed thereto to move back and forth.

[0016] The advantages of this application compared to the prior art are:

[0017] This application integrates the transmission mechanism (including the middle shell assembly, the headrest back cover motor assembly, and the adjustment drive component) entirely inside the headrest. By optimizing the component layout (such as the nested fixing of the lead screw nut sleeve and the middle shell, and the compact assembly of the motor and the headrest back cover), the overall volume is significantly reduced, avoiding the occupation of the internal space of the seat back and improving the flexibility of seat function integration.

[0018] This application also ensures stability through a multi-layered structure: the sliding rail claws of the middle shell and the guide rail of the headrest back cover form a sliding guide; the limiting sheet metal of the headrest rod connecting plate and the longitudinal limiting groove of the middle shell restrict the degree of rotational freedom; and the cooperation between the headrest rod guide sleeve and the headrest rod ensures stable support. Meanwhile, the design of the screw-nut transmission pair makes power transmission smoother and adjustment more precise, effectively avoiding jamming problems during adjustment.

[0019] This application enables convenient and precise adjustment of the headrest's fore-and-aft position via electric adjustment, allowing passengers to quickly find a comfortable position based on their body type and riding habits. At the same time, by optimizing the fit between the headrest and the head, it reduces the risk of neck injury during an impact, thus balancing comfort and safety.

[0020] This application reduces the overall weight by simplifying the transmission chain (using lead screw and nut transmission as the core and reducing redundant parts) and optimizing the material layout. At the same time, the components are assembled using standardized connection methods such as snaps and bolts (e.g., snaps and bolts to fix the front and back covers of the headrest, and bolts to fix the motor and the back cover of the headrest), making the assembly process simpler and improving production efficiency. Attached Figure Description

[0021] Figure 1 This is a perspective view of an electric fore-and-aft adjustable headrest mechanism for a car seat, based on the present invention, from a first-person perspective.

[0022] Figure 2 This is a first exploded view of an electric fore-and-aft adjustable headrest mechanism for a car seat according to this utility model.

[0023] Figure 3 This is an exploded view of the middle shell mechanism assembly in an electric fore-and-aft adjustable headrest mechanism for a car seat according to this utility model.

[0024] Figure 4 This is a schematic diagram of the rear cover motor assembly in an electric fore-and-aft adjustable headrest mechanism for a car seat according to this utility model.

[0025] Figure 5 This is a schematic diagram of the interior of the front cover in an electric fore-and-aft adjustable headrest mechanism for a car seat according to this utility model.

[0026] Figure 6 This is a schematic diagram of the headrest rod connecting plate and the middle shell in an electric fore-and-aft adjustable headrest mechanism for a car seat according to this utility model.

[0027] Figure 7 This is a second exploded view of an electric fore-and-aft adjustable headrest mechanism for a car seat according to this utility model.

[0028] Figure 8This is a perspective view of an electric fore-and-aft adjustable headrest mechanism for a car seat, as described in this utility model, from a second perspective.

[0029] The following are the labels in the diagram: 1. Outer shell bolt; 2. Headrest front cover; 3. Headrest rod; 4. Headrest rear cover; 5. Motor lead screw assembly; 6. Headrest rod guide sleeve; 7. Lead screw nut sleeve; 8. Middle shell; 9. Headrest rod connecting plate; 10. Motor fixing bolt; 11. Lead screw nut sleeve fixing bolt; 12. Lead screw welding nut; 21. Mounting clip; 22. Inner guide rail; 23. Front positioning post; 24. Front cover bolt through hole; 31. Headrest rod groove; 32. Headrest rod center hole; 41. Clip groove; 42. Outer guide rail; 43. Rear positioning post; 4 4. Rear cover motor bolt limiting hole; 45. Rear cover bolt fixing hole; 51. Motor; 52. Motor bolt fixing hole; 53. Motor lead screw; 54. Motor wire; 61. Middle shell guide sleeve fixing buckle; 71. Lead screw nut sleeve lead screw hole; 72. Lead screw nut sleeve bolt fixing hole; 81. Middle shell slide rail claw; 82. Middle shell guide sleeve buckle fixing groove; 83. Middle shell through holes on both sides; 84. Middle shell lead screw nut sleeve limiting hole; 85. Middle shell lead screw nut sleeve bolt fixing hole; 86. Guide sleeve mounting groove; 87. Longitudinal limiting groove; 91. Limiting sheet metal. Detailed Implementation

[0030] To further understand the features, technical means, and specific objectives and functions achieved by this utility model, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and specific embodiments.

[0031] like Figure 1 , Figure 2 , Figure 7 and Figure 8 As shown, an electric fore-and-aft adjustable headrest mechanism for a car seat includes a middle shell assembly, comprising a middle shell 8 and two headrest rods 3 vertically disposed within the middle shell 8; an outer shell assembly, movably sleeved on the outside of the middle shell 8 in a front-to-back direction, the bottom of the outer shell assembly having an opening extending in a front-to-back direction through which the headrest rods 3 pass; and an adjustment drive assembly, comprising a lead screw nut sleeve 7 disposed within the middle shell 8, its axis extending in a front-to-back direction; a motor lead screw 53 rotatably disposed within the outer shell assembly and coaxially threadedly connected to the lead screw nut sleeve 7; and a motor 51 disposed on the inner wall of the outer shell assembly, its output shaft being drively connected to the motor lead screw 53; wherein, when the motor 51 drives the motor lead screw 53 to rotate, the threaded engagement between the motor lead screw 53 and the lead screw nut sleeve 7 causes the outer shell assembly to move relative to the middle shell assembly in a front-to-back direction.

[0032] like Figure 2 and Figure 7As shown, the outer shell assembly includes a front headrest cover 2 and a rear headrest cover 4. The front headrest cover 2 is provided with mounting buckles 21 on its periphery, and the rear headrest cover 4 is provided with buckle grooves 41 on its periphery. The mounting buckles 21 are snapped into the buckle grooves 41. The motor 51 is located inside the rear headrest cover 4.

[0033] like Figure 3 As shown, the middle shell 8 is also provided with guide sleeve mounting grooves 86 on both sides along its width direction. The middle shell mechanism assembly also includes two headrest rod guide sleeves 6. The two headrest rod guide sleeves 6 are respectively inserted into the guide sleeve mounting grooves 86 of the middle shell 8, and the two headrest rods 3 are respectively inserted into the two headrest rod guide sleeves 6.

[0034] like Figure 4 As shown, rear positioning posts 43 are provided on both sides of the headrest back cover 4, and rear positioning holes coupled to the rear positioning posts 43 are provided in the middle shell 8.

[0035] The middle shell 8 is also provided with a lead screw nut slot extending along its thickness direction. The lead screw nut sleeve 7 is inserted into the lead screw nut slot and fixed by screws.

[0036] like Figure 4 As shown, front positioning posts 23 are provided on both sides of the headrest front cover 2, and the front positioning posts 23 are inserted into and cooperate with the rear positioning posts 43.

[0037] like Figure 2 and Figure 3 As shown, the headrest rod 3 is provided with a headrest rod groove 31 that connects to the backrest guide tube. The headrest rod 3 is hollow and is used for the power supply line to pass through and connect to the backrest wiring harness.

[0038] like Figure 2 As shown, the bottom end of the middle shell 9 is provided with a longitudinal limiting groove 81. The middle shell assembly also includes a headrest rod connecting plate 9. The lower end of the headrest rod connecting plate 9 is provided with two limiting sheet metal pieces. The limiting sheet metal pieces are inserted into the two longitudinal limiting grooves 81 of the middle shell 9. The two sides of the headrest rod connecting plate 9 are fixedly connected to two headrest rods 3.

[0039] like Figure 4 As shown, the headrest back cover 4 is provided with guide rails 42 on both sides, and the middle shell 8 is also provided with a middle shell slide rail claw 81 coupled with the guide rails 42 to achieve a front and rear sliding connection with the middle shell mechanism assembly.

[0040] like Figure 5 As shown, the headrest front cover 2 is also provided with guide inner rails 22 on both sides, the guide inner rails 22 and the guide outer rails 42 slide together, and the headrest front cover 2 and the headrest back cover 4 are fixedly connected by bolts.

[0041] After the motor 51 is powered on, the motor lead screw 53 rotates inside the lead screw nut sleeve 7. The lead screw nut sleeve 7 is fixed to the middle shell 8 and the headrest rod 3. The rotation of the lead screw drives the motor 51 and the headrest front cover 2 and headrest back cover 4 fixed thereto to move back and forth.

[0042] The electric fore-and-aft adjustable headrest mechanism for automobile seats disclosed in this application mainly consists of three parts: the front cover 2, the middle shell mechanism assembly, and the rear cover motor assembly. The specific assembly and working method of each component are as follows:

[0043] Assembly of the middle shell assembly:

[0044] The middle shell assembly includes two headrest rods 3, a middle shell 8, a headrest rod connecting plate 9, and two headrest rod guide sleeves 61.

[0045] The two headrest rod guide sleeves 6 are respectively inserted into the guide sleeve mounting grooves 86 of the middle shell 8, and a stable connection is achieved through the middle shell guide sleeve fixing buckle 61 and the middle shell guide sleeve fixing groove 82.

[0046] Two headrest rods 3 are inserted into two headrest rod guide sleeves 6 respectively, and the lower end of the headrest rod 3 is fixed to the seat back tube through the headrest rod positioning groove 31.

[0047] The two limiting sheet metal pieces 91 at the lower end of the headrest rod connecting plate 9 are inserted into the two longitudinal limiting grooves 87 of the middle shell 8, and their two side edges are welded and fixed to the two headrest rods 3 to form an integral support structure, ensuring the relative position of the headrest rods 3 and the middle shell 8 is stable.

[0048] Assembly of the rear cover motor assembly:

[0049] The rear cover motor assembly includes a headrest rear cover 4, a motor lead screw assembly 5, a lead screw nut sleeve 7, and a lead screw welding nut 122.

[0050] The lead screw nut sleeve 7 is rotatably mounted on the motor lead screw 53 through the lead screw nut sleeve lead screw hole 71 inside it, and the lead screw welding nut 12 is welded and fixed to the top of the motor lead screw 53, forming a lead screw transmission pair.

[0051] The motor 51 of the motor lead screw assembly 5 is inserted into the motor groove 46 of the headrest back cover 4. The motor 51 is fixed to the headrest back cover 4 by passing the motor fixing bolt 10 through the motor bolt limiting hole 44 and the motor bolt fixing hole 52.

[0052] The motor wire 54 passes through the center hole 32 of the headrest rod 3 and is used to connect with the seat back wiring harness to realize power supply control.

[0053] Connection between the middle shell assembly and the rear cover motor assembly:

[0054] The rear positioning post 43 and the guide rail 42 of the headrest back cover 4 are respectively inserted into the through holes 83 on both sides of the middle shell 8 and the middle shell slide rail claws 81, forming a front and rear sliding fit structure 3.

[0055] The lead screw nut sleeve 7 is inserted into the lead screw nut sleeve limiting hole 84 of the middle shell 8, and the lead screw nut sleeve 7 is fixed to the middle shell 8 by passing through the lead screw nut sleeve fixing bolt 11 through the lead screw nut sleeve bolt fixing hole 85 and the lead screw nut sleeve bolt fixing hole 72.

[0056] This structure ensures that the rear cover motor assembly can slide smoothly relative to the middle shell assembly in the front-to-back direction, while limiting lateral displacement.

[0057] Assembly of the front and rear covers:

[0058] The front positioning post 23 and the inner guide rail 22 of the front cover 2 are inserted into the rear positioning post 43 and the outer guide rail 42 of the headrest back cover 4 to form a guiding fit.

[0059] The mounting clips 21 around the front cover 2 are inserted into the clip slots 41 of the headrest back cover 4 to achieve pre-fixation.

[0060] Four outer shell bolts 1 pass through the front cover bolt through hole 24 and the rear cover bolt fixing hole 45 respectively, fastening the front cover 2 and the headrest rear cover 4 to form a closed headrest outer shell.

[0061] Adjustment function implementation:

[0062] When the motor 51 is powered on, the motor lead screw 53 rotates inside the lead screw nut sleeve 7. Since the lead screw nut sleeve 7 is fixed as a whole with the middle shell 8 and the headrest rod 3, the rotational motion of the motor lead screw 53 is converted into the forward and backward linear motion 4 of the motor 51 and the headrest front cover 2 and the headrest rear cover 4 fixed therewith through the threaded connection.

[0063] By controlling the forward and reverse rotation of motor 51, the headrest outer shell can be extended forward or retracted backward relative to the middle shell mechanism assembly, thereby adjusting the front and rear position of the headrest.

[0064] The fit between the limiting sheet metal 91 of the headrest rod connecting plate 9 and the longitudinal limiting groove 87 of the middle shell, as well as the guiding function of the headrest rod guide sleeve 6 and the middle shell 8, ensures that the adjustment process is stable and without shaking.

[0065] This application achieves a compact structure and small footprint by integrating the transmission mechanism inside the headrest. At the same time, the combination of screw drive and sliding guide structure ensures the smoothness and reliability of the adjustment process, making it suitable for headrest modification and new installation needs of most car seats on the market.

[0066] The working principle of the electric fore-and-aft adjustment headrest mechanism for automobile seats in this application is based on the synergistic effect of lead screw and nut transmission and sliding guide structure, and the electric fore-and-aft adjustment of the headrest is achieved through the following steps:

[0067] When the user sends an adjustment command through the seat control panel, the current is transmitted to the motor 51 through the motor wire 54 in the center hole 32 of the headrest rod.

[0068] When the motor 51 is powered on, it drives the motor screw 53 to rotate, thus forming a power source.

[0069] The motor lead screw 53 and the lead screw nut sleeve 7 are connected by a threaded pair.

[0070] Since the lead screw nut sleeve 7 is fixed to the middle shell lead screw nut sleeve limiting hole 84 of the middle shell 8 through the lead screw nut sleeve fixing bolt 11, and the middle shell 8 is rigidly connected to the headrest rod 3 through the headrest rod guide sleeve 6, the lead screw nut sleeve 7 cannot move.

[0071] Therefore, the rotational motion of the motor lead screw 53 is converted into linear motion of the motor 51 and the headrest back cover 4 fixed thereto along the axis of the lead screw.

[0072] The guide rail 42 of the headrest back cover 4 and the sliding rail claw 81 of the middle shell 8 form a sliding engagement. At the same time, the rear positioning post 43 is inserted into the through holes 83 on both sides of the middle shell 8 to limit lateral displacement and ensure linear motion accuracy.

[0073] The front cover 2 is nested with the guide outer rail 42 of the headrest back cover 4 via the guide inner rail 22, and moves synchronously with the back cover to form a complete headrest shell adjustment.

[0074] The limiting sheet metal 91 of the headrest rod connecting plate 9 is inserted into the longitudinal limiting groove 87 of the middle shell 8 to limit the rotational freedom of the headrest rod 3 and enhance the structural stability.

[0075] The stroke of the motor lead screw 53 is limited by the relative position of the lead screw weld nut 12 and the lead screw nut sleeve 7 to prevent excessive movement.

[0076] After the motor wire 54 is led out from the center hole 32 of the headrest rod, it is connected to the wire harness in the seat back tube through the positioning groove 31 of the headrest rod to realize signal and power transmission, while avoiding wire tangling during adjustment.

[0077] The above embodiments only illustrate one or more implementations of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of protection of this utility model. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the scope of protection of this utility model. Therefore, the scope of protection of this utility model should be determined by the appended claims.

Claims

1. An electrically powered fore-aft adjustment headrest mechanism for a motor vehicle seat, characterised in that, include, The middle shell assembly includes the middle shell and two headrest rods vertically arranged in the middle shell; The outer shell assembly is movably fitted onto the outer side of the middle shell in the front-back direction, and the bottom of the outer shell assembly is provided with an opening extending in the front-back direction, through which the headrest rod passes; Adjustment drive components, including, The lead screw nut sleeve is housed in the middle shell, and its axis extends in the front-to-back direction; The motor lead screw is rotatably mounted in the housing assembly and is coaxially threadedly connected to the lead screw nut sleeve; The motor is located on the inner wall of the housing assembly, and its output shaft is connected to the motor lead screw drive. When the motor drives the motor screw to rotate, the threaded engagement between the motor screw and the screw nut causes the outer shell assembly to move relative to the middle shell assembly in the front-to-back direction.

2. The electric fore-and-aft adjustable headrest mechanism for a car seat according to claim 1, characterized in that, The outer casing assembly includes a front cover and a back cover of the headrest. The front cover of the headrest is provided with mounting buckles on its periphery, and the back cover of the headrest is provided with buckle grooves on its periphery. The mounting buckles are connected to the buckle grooves, and the motor is located inside the back cover of the headrest.

3. A car seat electric fore-and-aft adjustable headrest mechanism according to claim 1 or 2, characterized in that, The middle shell is also provided with guide sleeve mounting grooves on both sides along its width direction. The middle shell assembly also includes two headrest rod guide sleeves. The two headrest rod guide sleeves are respectively inserted into the guide sleeve mounting grooves of the middle shell, and the two headrest rods are respectively inserted into the two headrest rod guide sleeves.

4. The electric fore-and-aft adjustable headrest mechanism for a car seat according to claim 2, characterized in that, The headrest back cover is also equipped with rear positioning posts on both sides, and the middle shell is also equipped with rear positioning holes that are coupled with the rear positioning posts.

5. The electric fore-and-aft adjustable headrest mechanism for a car seat according to claim 4, characterized in that, The headrest front cover has front positioning posts on both sides, which are inserted into and fitted with rear positioning posts.

6. The electric fore-and-aft adjustable headrest mechanism for a car seat according to claim 1, characterized in that, The headrest rod has a groove for connecting to the backrest guide tube. The headrest rod is hollow and is used for the motor wire to pass through and connect to the backrest wiring harness.

7. The electric fore-and-aft adjustable headrest mechanism for a car seat according to claim 3, characterized in that, The bottom of the middle shell is provided with a longitudinal limiting groove. The middle shell assembly also includes a headrest rod connecting plate. The lower end of the headrest rod connecting plate is provided with two limiting sheet metal pieces. The limiting sheet metal pieces are inserted into the two longitudinal limiting grooves of the middle shell. The two sides of the headrest rod connecting plate are fixedly connected to two headrest rods.

8. The electric fore-and-aft adjustable headrest mechanism for a car seat according to claim 4, characterized in that, The headrest back cover is equipped with guide rails on both sides, and the middle shell is also equipped with middle shell slide rail claws that are coupled with the guide rails to achieve front and rear sliding connection with the middle shell mechanism assembly.

9. A car seat electric fore-and-aft adjustable headrest mechanism according to claim 5, characterized in that, The headrest front cover is also provided with inner guide rails on both sides, which slide with the outer guide rails. The headrest front cover and the headrest back cover are fixedly connected by bolts.

10. The electric fore-and-aft adjustable headrest mechanism for a car seat according to claim 1, characterized in that, After the motor is powered on, the motor lead screw rotates inside the lead screw nut sleeve. The lead screw nut sleeve is fixed to the middle shell and the headrest rod. The rotation of the lead screw drives the motor and the front and back covers of the headrest that are fixed to it to move back and forth.

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