Adjustable lower hinge

Abstract

The utility model discloses an adjustable lower hinge which comprises a frame fixing seat, a sash fixing seat, a connecting rod assembly, an adjusting block, a first adjusting screw, a second adjusting screw and an eccentric nail, and a first through hole is formed in the sash fixing seat; the connecting rod assembly comprises a first connecting rod, a second connecting rod, a third connecting rod and a fourth connecting rod; the second connecting rods are connected with rotating shafts; the rotating shaft can swing relative to the second connecting rod and is rotationally connected with the fan fixing seat; the adjusting block is in sliding fit with the sash fixing seat; the tail end of the first adjusting screw abuts against the rotating shaft. The tail end of the second adjusting screw abuts against the sash frame. The eccentric nail comprises a first rotating part and an adjusting part, and the adjusting part extends into the first through hole. According to the adjustable lower hinge, three-dimensional independent adjustment of a window sash in the vertical direction, the horizontal direction and the depth direction is achieved, all adjusting parts are arranged in a centralized mode, a user can complete multi-dimensional calibration without switching the adjusting position, and the adjusting efficiency and precision are remarkably improved.

Description

An adjustable bottom hinge Technical Field

[0001] This utility model relates to the technical field of door and window hardware accessories, and in particular to an adjustable lower hinge. Background Technology

[0002] In recent years, with the development of building door and window technology, inward-opening and tilt-and-turn windows have gradually become one of the mainstream window types in modern buildings because they combine both inward opening and tilt-and-turn opening methods. These windows achieve large-angle ventilation by opening the sash inward, or create a micro-ventilation mode by tilting it inward at a certain angle, combining safety, airtightness, and flexibility.

[0003] In door and window hardware systems, the bottom hinge, as a core component connecting the window frame and sash, must bear the weight of the sash during opening and closing, and also possess position adjustment capabilities to accommodate installation errors or deformation caused by long-term use. In existing technologies, the position adjustment function of the bottom hinge is typically achieved through dispersed components: for example, horizontal adjustment screws are installed on the frame mounting base to adjust the left and right position of the sash, vertical adjustment screws are installed on the sash mounting base to control the height, and depth adjustment relies on the installation position of the adjustment linkage assembly. This dispersed adjustment design results in the operating interface being scattered across different locations on the hinge. Users must navigate between multiple adjustment components on the frame mounting base, sash mounting base, and linkage assembly, a cumbersome process that makes precise and coordinated control of positional changes in all directions difficult. Ultimately, this leads to poor sealing between the sash and the window frame, and insufficient long-term stability.

[0004] It is evident that existing technologies still need improvement and enhancement. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this utility model is to provide an adjustable lower hinge, which aims to solve the technical problem that the lower hinge in the prior art is difficult to calibrate the window sash position due to the dispersed operation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An adjustable lower hinge, comprising:

[0008] Frame mounting bracket, used for installation on window frames;

[0009] A fan mounting bracket is used to install the fan frame; the fan mounting bracket has a first through hole.

[0010] The linkage assembly consists of a first link, a second link, a third link, and a fourth link. The middle parts of the first link and the second link are pivotally connected. One end of the first link is hinged to the frame fixing seat, and the other end is hinged to one end of the third link. The other end of the third link is hinged to the sash fixing seat. One end of the second link is connected to a pivot, and the other end is hinged to one end of the fourth link. The other end of the fourth link is hinged to the frame fixing seat. The pivot can swing relative to the second link in a vertical plane, and the pivot is rotatably connected to the sash fixing seat.

[0011] Adjustment block, used to be installed on the fan frame and to form a sliding fit with the fan mounting base;

[0012] The first adjusting screw is screwed into the fan mounting base and its end abuts against the rotating shaft;

[0013] The second adjusting screw is screwed to the fan mounting base and its end abuts against the fan frame; its axis is perpendicular to the axis of the first adjusting screw.

[0014] An eccentric screw includes a first rotating part rotatably connected to an adjusting block and an adjusting part connected to the first rotating part, the adjusting part extending into a first through hole and having its axis parallel to the axis of a second adjusting screw.

[0015] Furthermore, the second connecting rod has a second through hole; the lower end of the rotating shaft has a shoulder and an insertion part at the bottom of the shoulder, the insertion part being inserted into the second through hole; the shoulder has an abutting slope on the side near the insertion part, and when the rotating shaft swings, the abutting slope contacts the upper surface of the second connecting rod; a rivet is riveted to the fan fixing seat, and a second rotating part is provided on the rivet, the second rotating part being rotatably connected to the third connecting rod, and the height of the second rotating part being greater than the thickness of the third connecting rod.

[0016] Furthermore, the second through hole includes two parallel first planes and a first arc surface connecting the two first planes, and the insertion part includes two parallel second planes and a second arc surface connecting the two second planes. The second arc surface gradually contracts inward in the downward direction, and each first plane corresponds to a second plane in contact.

[0017] Furthermore, a limiting block is provided at the end of the fan fixing seat away from the rotating shaft; an avoidance notch is provided on the third connecting rod, which is used to avoid the limiting block when the fan fixing seat swings.

[0018] Furthermore, the fan mounting base is provided with a pin, and the frame mounting base has a third through hole corresponding to the position of the pin, and the pin can be inserted into the third through hole.

[0019] Furthermore, the pin is provided with a relief slope to guide the pin into or out of the third through hole.

[0020] Furthermore, the adjusting block is provided with two vertically arranged first guide blocks, and the two first guide blocks are provided with parallel guide slopes on one side of their respective sides; the fan fixing seat is provided with a second guide block, and the second guide block slides in cooperation with the two guide slopes.

[0021] Furthermore, the first guide block located above is screwed with a set screw, which abuts against the sector frame to fix the position of the adjusting block.

[0022] Furthermore, it also includes a detachable positioning block, which is inserted into the fan mounting base and has one side wall abutting against the first guide block.

[0023] Beneficial effects:

[0024] This utility model provides an adjustable lower hinge, which achieves three-dimensional independent adjustment of the window sash in the vertical, horizontal and depth directions by integrating a first adjusting screw (up and down adjustment), a second adjusting screw (left and right adjustment) and an eccentric nail (front and back adjustment) in the sash fixing seat, in conjunction with the vertical sliding restriction of the adjusting block; all adjusting components are centrally located, and users can complete multi-dimensional calibration without switching the adjustment position, significantly improving adjustment efficiency and accuracy. Attached Figure Description

[0025] Figure 1 is a structural diagram of the adjustable lower hinge provided by this utility model;

[0026] Figure 2 is a structural diagram of the adjustable lower hinge provided by this utility model when the window sash is closed;

[0027] Figure 3 is an exploded view of the adjustable lower hinge provided by this utility model when the window is closed;

[0028] Figure 4 is a cross-sectional view of the adjustable lower hinge provided by this utility model when it is folded down inside the window sash;

[0029] Figure 5 is a structural diagram of the adjustable lower hinge provided by this utility model when the window sash is opened within 180°;

[0030] Figure 6 is an exploded view of the adjustable lower hinge provided by this utility model when the window sash is opened within 180°;

[0031] Figure 7 is a structural diagram of the adjustable lower hinge pivot provided by this utility model.

[0032] Reference numerals: Frame fixing seat 1, third through hole 11, fan fixing seat 2, first through hole 21, rivet 22, second rotating part 221, limiting block 23, pin 24, clearance slope 241, second guide block 25, connecting rod assembly 3, first connecting rod 31, second connecting rod 32, second through hole 321, first plane 3211, first arc surface 3212, third connecting rod 33, clearance notch 331, fourth connecting rod 34, rotating shaft 4, shoulder 41, insertion part 42, second plane 421, second arc surface 422, abutting slope 43, adjusting block 5, first guide block 51, guide slope 52, set screw 53, first adjusting screw 6, second adjusting screw 7, eccentric nail 8, first rotating part 81, adjusting part 82, positioning block 9. Detailed Implementation

[0033] This utility model provides an adjustable lower hinge. To make the purpose, technical solution, and effects of this utility model clearer and more explicit, the following describes this utility model in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0034] In the description of this utility model, it should be understood that the terms "upper," "lower," "left," "right," "front," and "rear," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation. Therefore, they should not be construed as limitations on this utility model. Furthermore, "first" and "second" are only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "multiple" means two or more.

[0035] In this invention, the direction perpendicular to the window sash when it is closed is defined as the front-to-back direction, and the width direction of the window sash is defined as the left-to-right direction. The hardware for the inward-opening and tilt-and-turn window includes a handle, a transmission structure, an upper hinge, and a lower hinge. By rotating the handle, the transmission structure is controlled to move the upper hinge. The upper and lower hinges work together to achieve the window sash opening, tilting, and closing. The lower hinge is a follower component.

[0036] Please refer to Figures 1 to 7. This utility model provides an adjustable lower hinge, including: a frame fixing seat 1, a sash fixing seat 2, a connecting rod assembly 3, an adjusting block 5, a first adjusting screw 6, a second adjusting screw 7, and an eccentric nail 8; the frame fixing seat 1 is used to install on the window frame; the sash fixing seat 2 is used to install on the sash frame; the sash fixing seat 2 has a first through hole 21; the connecting rod assembly 3 is composed of a first connecting rod 31, a second connecting rod 32, a third connecting rod 33, and a fourth connecting rod 34. The middle part of the first connecting rod 31 and the middle part of the second connecting rod 32 are pivotally connected. One end of the first connecting rod 31 is hinged to the frame fixing seat 1, and the other end is hinged to one end of the third connecting rod 33. The other end of the third connecting rod 33 is hinged to the sash fixing seat 2; one end of the second connecting rod 32 is connected to a rotating... Shaft 4, with one end hinged to one end of the fourth connecting rod 34, and the other end of the fourth connecting rod 34 hinged to the frame fixing seat 1; the rotating shaft 4 can swing relative to the second connecting rod 32 in the vertical plane, and the rotating shaft 4 is rotatably connected to the fan fixing seat 2; the adjusting block 5 is used to be installed on the fan frame and forms a sliding fit with the fan fixing seat 2; the first adjusting screw 6 is screwed to the fan fixing seat 2 and its end abuts against the rotating shaft 4; the second adjusting screw 7 is screwed to the fan fixing seat 2 and its end abuts against the fan frame; its axis is perpendicular to the axis of the first adjusting screw 6; the eccentric nail 8 includes a first rotating part 81 rotatably connected to the adjusting block 5 and an adjusting part 82 connected to the first rotating part 81, the adjusting part 82 extends into the first through hole 21 and its axis is parallel to the axis of the second adjusting screw 7.

[0037] In the above description, the frame fixing seat 1 is installed in the mounting groove of the window frame, the sash fixing seat 2 is installed in the horizontal mounting groove of the sash window, and the adjusting block 5 is installed in the vertical mounting groove of the sash frame. The axis of the first adjusting screw 6 is vertical, while the axis of the second adjusting screw 7 and the axis of the eccentric screw 8 are both horizontal.

[0038] When the window sash is open, as shown in Figures 1 and 5, in the inward-opening state, the linkage assembly 3 unfolds. The first linkage 31, second linkage 32, third linkage 33, and fourth linkage 34 swing in tandem on the horizontal plane under the influence of the sash frame, and the sash fixing seat 2 rotates around the axis of rotation 4 to achieve an inward opening action of the window sash from 0° to 180°. As shown in Figure 4, in the tilt-in state, the linkage assembly 3 is in its initial state, with the first linkage 31 and second linkage 32 stacked. The rotation axis 4 swings relative to the second linkage 32 towards the interior, causing the sash fixing seat 2 to tilt, thus tilting the window sash inward and achieving micro-ventilation. During this process, the sash fixing seat 2, the first linkage 31, and the second linkage 32 form a stable support by pressing against the frame fixing seat 1, effectively preventing the window sash from sagging and increasing the load-bearing strength in the tilt-in state.

[0039] The left and right position of the window sash is adjusted by the second adjusting screw 7 screwed to the sash fixing seat 2. The end of the second adjusting screw 7 abuts against the vertical mounting groove of the window frame. Rotating the second adjusting screw 7 adjusts the horizontal distance between the vertical mounting groove of the sash frame and the vertical section of the sash fixing seat 2, thereby adjusting the left and right position of the window sash to compensate for the horizontal installation deviation of the window sash.

[0040] The vertical position adjustment of the window sash is achieved by the first adjusting screw 6 screwed to the sash fixing seat 2. The end of the first adjusting screw 6 abuts against the top of the rotating shaft 4. Rotating the first adjusting screw 6 pushes the sash fixing seat 2 to slide in the vertical direction, thereby adjusting the installation height of the window sash.

[0041] The front and rear position adjustment of the window sash is achieved by an eccentric nail 8 rotatably connected to the adjusting block 5. The axis of the first rotating part 81 of the eccentric nail 8 has an eccentric distance between it and the axis of the adjusting part 82. The adjusting part 82 is located inside the first through hole 21. By rotating the adjusting part 82, the change in the eccentric distance between its first rotating part 81 and the adjusting part 82 in the horizontal direction drives the fine adjustment of the horizontal distance between the adjusting block 5 and the sash fixing seat 2, ensuring that the window sash fits tightly against the window frame.

[0042] All adjustments are concentrated in the vertical mounting area of ​​the sash fixing base 2 and the adjusting block 5, enabling centralized adjustment of the window sash's left-right, up-down, and front-back positions. During adjustment, each direction can be operated independently without interference. Users can accurately adjust the window sash position without having to operate multiple components, significantly improving adjustment efficiency and ease of operation. In addition, the three-dimensional position adjustment ensures the window sash's airtightness.

[0043] In a preferred embodiment, referring to Figures 3, 4, and 6, the second connecting rod 32 has a second through hole 321; the lower end of the rotating shaft 4 has a shoulder 41 and an insertion part 42 located at the bottom of the shoulder 41, the insertion part 42 being inserted into the second through hole 321; the shoulder 41 has an abutting slope 43 on the side near the insertion part 42, and when the rotating shaft 4 swings, the abutting slope 43 contacts the upper surface of the second connecting rod 32. When the window sash is closed or inwardly open, the shoulder 41 on the rotating shaft 4 abuts against the upper surface of the second connecting rod 32, directly supporting the rotating shaft 4 through the second connecting rod 32, thus enhancing the stability of the window sash. When the window sash is open, the insertion part 42 cooperates with the second through hole 321 to restrict the displacement of the rotating shaft 4, keeping the rotating shaft 4 stationary relative to the second connecting rod 32, while the sash fixing seat 2 rotates around the rotating shaft 4. During the inward tilting process, the connecting rod assembly 3 is in its initial state, and the rotating shaft 4 swings towards the interior on the vertical plane. The insertion part 42 cooperates with the second through hole 321 to guide the rotating shaft 4 to tilt, and finally the inclined surface 43 abuts against the upper surface of the second connecting rod 32, forming a stable support for the fan fixing seat 2.

[0044] Furthermore, referring to Figures 3 and 6, a rivet 22 is riveted to the fan mounting base 2. The rivet 22 has a second rotating part 221, which is rotatably connected to the third connecting rod 33. The height of the second rotating part 221 is greater than the thickness of the third connecting rod 33. This arrangement provides rotational space for the fan mounting base 2 and limits unnecessary deflection of the third connecting rod 33 caused by the movement of the fan mounting base 2.

[0045] Further, referring to Figure 7, the second through hole 321 includes two parallel first planes 3211 and a first arc surface 3212 connecting the two first planes 3211. The insertion part 42 includes two parallel second planes 421 and a second arc surface 422 connecting the two second planes 421. The second arc surface 422 gradually tapers inward in the downward direction, and each first plane 3211 contacts one second plane 421. During installation, the second planes 421 of the insertion part 42 contact the first planes 3211 of the second through hole 321 one by one, restricting the rotation of the shaft 4 around its own axis through planar contact. At the same time, the second arc surface 422 and the first arc surface 3212 form a guiding fit, allowing the shaft 4 to swing inward in the vertical plane, thereby driving the sash fixing seat 2 to tilt and realize the inward tilting action of the window sash. This structure, through the dual cooperation of the planes and arc surfaces, ensures both rigid support when the window sash opens inward and provides a precise swing path for the inward tilting movement, taking into account both stability and freedom of movement.

[0046] Furthermore, referring to Figures 3 and 6, a limiting block 23 is provided at the end of the sash fixing seat 2 away from the rotating shaft 4; this limiting block 23 is located on the side of the sash fixing seat 2 closer to the interior, and is used to constrain the sash fixing seat 2 to tilt only inward. A clearance notch 331 is provided on the third link 33, which is used to avoid the limiting block 23 when the sash fixing seat 2 swings. When the window sash tilts inward, the sash fixing seat 2 swings with the rotating shaft 4, and the clearance notch 331 provides movement space for the limiting block 23, avoiding rigid interference between the limiting block 23 and the third link 33, thereby ensuring the smoothness of the window sash tilting inward. Through the cooperation of the limiting block 23 and the clearance notch 331, both unintended deflection of the sash fixing seat 2 and the stability of the movement trajectory of the link assembly 3 are limited.

[0047] In a preferred embodiment, referring to Figures 2 and 3, the sash fixing seat 2 is provided with a pin 24, and the frame fixing seat 1 has a third through hole 11 corresponding to the position of the pin 24, into which the pin 24 can be inserted. When the window sash is closed and subjected to positive wind pressure, the wind pressure load is transmitted through the window sash to the sash fixing seat 2, causing the pin 24 to be tightly pressed against the inner wall of the third through hole 11, thereby locking the position of the sash fixing seat 2. The cooperation between the pin 24 and the third through hole 11 significantly enhances the wind pressure resistance of the window sash.

[0048] Further, referring to Figures 2 and 3, the latch 24 is provided with a relief slope 241 to guide the latch 24 into or out of the third through hole 11. During the opening and closing of the window sash, the sash fixing seat 2 rotates around the pivot 4, and the latch 24 smoothly disengages from or extends into the third through hole 11. By providing the relief slope 241, frictional interference between the latch 24 and the inner wall of the third through hole 11 is avoided, ensuring smooth and unobstructed opening and closing of the window sash.

[0049] In a preferred embodiment, referring to Figure 3, the adjusting block 5 is provided with two vertically arranged first guide blocks 51, and each of the two first guide blocks 51 has a parallel guide ramp 52 on one side corresponding to the other; the sash fixing seat 2 is provided with a second guide block 25, which slides in cooperation with the two guide ramps 52. When adjusting the left and right position of the window sash, rotating the second adjusting screw 7 pushes the adjusting block 5 to move horizontally. The cooperation between the guide ramps 52 and the second guide blocks 25 constrains the movement trajectory of the adjusting block 5, allowing it to move smoothly in the left and right direction with adaptive vertical displacement, thus avoiding swaying during the adjustment process.

[0050] Further, referring to Figure 3, the first guide block 51 located at the top is screwed with a set screw 53, which abuts against the sash frame to fix the position of the adjusting block 5. During adjustment, the adjusting block 5 is embedded in the mounting groove of the sash frame and can move up and down along the mounting groove. By adjusting the second adjusting screw 7, the left and right mounting positions of the window frame are adjusted, and by rotating the eccentric nail 8, the front and back positions of the window frame are adjusted. Finally, the set screw 53 is locked so that its end abuts against the sash frame to fix the position of the adjusting block 5. Through the above settings, the synergistic effect of the inclined guide and the screw locking simplifies the operation process while ensuring the positioning accuracy and anti-offset stability of the adjusting block 5 in three-dimensional adjustment.

[0051] In a preferred embodiment, referring to Figure 3, a detachable positioning block 9 is also included. The positioning block 9 is inserted into the sash fixing seat 2, and one side wall abuts against the first guide block 51. During assembly, the positioning block 9 is inserted into the sash fixing seat 2, causing the second guide block 25 on the sash fixing seat 2 to engage with the guide slope 52 of the two first guide blocks 51. The initial position of the adjusting block 5 is constrained by the abutment of one side of the positioning block 9 against the first guide block 51, thereby achieving rapid pre-positioning of the adjusting block 5 within the sash frame mounting groove. During adjustment, the positioning block 9 is removed to release its restriction on the forward and backward movement of the adjusting block 5, ensuring that the forward and backward position of the window sash can be freely adjusted.

[0052] In summary, this utility model achieves three-dimensional independent adjustment of the window sash in the vertical, horizontal, and depth directions by screwing a first adjusting screw 6 and a second adjusting screw 7 onto the vertical section of the sash fixing base 2, and by rotatably connecting an eccentric nail 8 to the adjusting block 5. Rotating the first adjusting screw 6 adjusts the vertical position of the sash frame, rotating the second adjusting screw 7 adjusts the horizontal position of the sash frame, and rotating the eccentric nail 8 adjusts the front-to-back position of the sash frame. Furthermore, the 82 adjusting parts are concentrated in one location, eliminating the need for users to switch between multiple positions to perform multi-dimensional calibration of the window sash, significantly improving adjustment efficiency. The design of inserting the shaft 4's insertion part 42 into the second through hole 321 of the second connecting rod 32, combined with the combination of the flat and curved surfaces within the second through hole 321 and the contracting curved surface of the insertion part 42, provides rigid planar support to prevent sagging when the window sash is closed or opening inwards. When tilting inwards, the curved surface guides the shaft 4 to precisely swing, thereby stably controlling the tilt angle of the sash fixing base 2. In addition, a pin 24 with a clearance slope 241 is provided in the sash fixing seat 2, which cooperates with the third through hole 11 of the frame fixing seat 1. When the window sash is closed, the pin 24 is pressed tightly against the inner wall of the third through hole 11 by wind pressure to enhance wind pressure resistance. When opening and closing, the clearance slope 241 allows it to smoothly disengage or extend into the third through hole 11, avoiding friction interference between the pin 24 and the inner wall of the third through hole 11, and ensuring smooth and unobstructed opening and closing of the window sash.

[0053] It is understood that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of this utility model, and all such substitutions or changes should fall within the protection scope of the appended claims of this utility model.

Claims

1. An adjustable lower hinge, characterized in that, include: A frame fixing seat (1) is used to install on the window frame; a sash fixing seat (2) is used to install on the sash frame; the sash fixing seat (2) has a first through hole (21); a connecting rod assembly (3) is composed of a first connecting rod (31), a second connecting rod (32), a third connecting rod (33) and a fourth connecting rod (34). The middle part of the first connecting rod (31) and the middle part of the second connecting rod (32) are pivotally connected. One end of the first connecting rod (31) is hinged to the frame fixing seat (1), and the other end is hinged to one end of the third connecting rod (33). The other end of the third connecting rod (33) is hinged to the sash fixing seat (2); one end of the second connecting rod (32) is connected to a rotating shaft (4), and the other end is hinged to one end of the fourth connecting rod (34). The other end of the fourth connecting rod (34) is connected to the frame fixing seat (1). 1) Hinged; the pivot (4) can swing relative to the second link (32) in the vertical plane, and the pivot (4) is rotatably connected to the fan mounting base (2); the adjusting block (5) is used to be installed on the fan frame and forms a sliding fit with the fan mounting base (2); the first adjusting screw (6) is screwed to the fan mounting base (2) and its end abuts against the pivot (4); the second adjusting screw (7) is screwed to the fan mounting base (2) and its end abuts against the fan frame; its axis is perpendicular to the axis of the first adjusting screw (6); the eccentric nail (8) includes a first rotating part (81) rotatably connected to the adjusting block (5) and an adjusting part (82) connected to the first rotating part (81), the adjusting part (82) extending into the first through hole (21) and its axis being parallel to the axis of the second adjusting screw (7).

2. The adjustable lower hinge according to claim 1, characterized in that, The second connecting rod (32) has a second through hole (321); the lower end of the rotating shaft (4) has a shoulder (41) and an insertion part (42) at the bottom of the shoulder (41), the insertion part (42) is inserted into the second through hole (321); the shoulder (41) has an abutting slope (43) on the side near the insertion part (42), when the rotating shaft (4) swings, the abutting slope (43) contacts the upper surface of the second connecting rod (32); the fan fixing seat (2) is riveted with a rivet (22), the rivet (22) has a second rotating part (221), the second rotating part (221) is rotatably connected to the third connecting rod (33), and the height of the second rotating part (221) is greater than the thickness of the third connecting rod (33).

3. The adjustable lower hinge according to claim 2, characterized in that, The second through hole (321) includes two parallel first planes (3211) and a first arc surface (3212) connecting the two first planes (3211). The insertion part (42) includes two parallel second planes (421) and a second arc surface (422) connecting the two second planes (421). The second arc surface (422) gradually shrinks inward in the downward direction. Each first plane (3211) is in contact with a corresponding second plane (421).

4. The adjustable lower hinge according to claim 1, characterized in that, The fan mounting base (2) is provided with a limiting block (23) at one end away from the rotating shaft (4); the third link (33) has an avoidance notch (331) which is used to avoid the limiting block (23) when the fan mounting base (2) swings.

5. The adjustable lower hinge according to claim 1, characterized in that, The fan mounting base (2) is provided with a pin (24), and the frame mounting base (1) has a third through hole (11) corresponding to the position of the pin (24). The pin (24) can be inserted into the third through hole (11).

6. The adjustable lower hinge according to claim 5, characterized in that, The pin (24) is provided with a relief slope (241) to guide the pin (24) to be inserted into or disengaged from the third through hole (11).

7. The adjustable lower hinge according to claim 1, characterized in that, The adjusting block (5) is provided with two vertically arranged first guide blocks (51), and the two first guide blocks (51) are provided with parallel guide slopes (52) on one side of their respective sides; the fan fixing seat (2) is provided with a second guide block (25), and the second guide block (25) slides in cooperation with the two guide slopes (52).

8. The adjustable lower hinge according to claim 7, characterized in that, The first guide block (51) located above is screwed with a set screw (53), which abuts against the fan frame to fix the position of the adjusting block (5).

9. The adjustable lower hinge according to claim 8, characterized in that, It also includes a detachable positioning block (9), which is inserted into the fan fixing seat (2) and has one side wall abutting against the first guide block (51).

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