Patent Publication Number: US-2023137377-A1

Title: One-way damping structure and adjusting assembly comprising one-way damping structure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a vehicle seat, and more particularly to a one-way damping structure and an adjusting assembly comprising the one-way damping structure. 
     2. Related Art 
     In the prior art, for a seat with an electric height adjustment, a structure of a first-stage worm helical gear and a second-stage small tooth difference transmission is generally used to transmit motion and power of a motor to an output end, such that the seat is adjusted upwards and downward by a height adjustment mechanism for a seat basin. When the seat is adjusted upwards, with gravity of a load acting downward, the electric upward adjustment runs by defying the load all the time, wherein the helical gear is rotated driven by the motor in virtue of the worm all the time, and the second-stage small tooth difference is subsequently driven, such that the output gear is driven to lift the seat, and wherein the same tooth surface of the worm keeps meshing with the same tooth surface of the helical gear during the process. When the seat is adjusted downwards, with gravity of a load acting downward, there will be two situations. In one case, the helical gear is rotated driven by the motor in virtue of the worm, and the second-stage small tooth difference is subsequently driven, such that the output gear is driven to lower the seat. In the other case, the output gear is rotated driven by the load, the second-stage small tooth difference is subsequently driven, and the helical gear is subsequently driven, such that the worm is back-driven by the helical gear. Above two situations occur alternately when the internal resistance of the system is unstable, thus the meshing tooth surfaces of the worm and the helical gear are switched with each other, which in turn causes the instability of the second-stage small tooth difference transmission. The problems such as abnormal noise and unstable operation, etc are brought out in the downward adjustment. 
     In order to solve the problem of unstable operation when the seat is adjusted downwards, a circumferential spring and a wedge block structure are known to be incorporated into the product to increase the internal resistance of the system with gravity of the load acting downward. However, such increased internal resistance will decrease the lifting ability of the product during the upward adjustment, and the control of the internal resistance of the system will become more difficult. 
     SUMMARY OF THE INVENTION 
     In order to solve the problem of unstable operation when the seat is adjusted downwards in the prior art, the present invention provides a one-way damping structure and an adjustment assembly including the one-way damping structure. 
     The one-way damping structure according to the present invention comprises a spring, a drive element and a friction force generation member, wherein the spring and the drive element are connected such that the spring is driven by means of the drive element, wherein the spring comprises a fixing portion, a connecting portion and an annular portion, wherein the connecting portion is located between the fixing portion and the annular portion and connects the fixing portion to the annular portion, wherein the fixing portion is fixed, wherein the annular portion comprises at least half a turn spirally extending in a circumferential direction and defining a spring opening, and wherein the annular portion slides relative to the friction force generation member so as to generate a friction torque. 
     In preferred embodiments, the one-way damping structure comprises an installation shaft, which is formed as the friction force generation member, wherein the annular portion is around on the installation shaft in an interference fit manner such that the friction torque is generated by the slide of an internal wall defining the opening of the annular portion relative to an outer surface of the installation shaft. That is to say, the friction force generation member is the installation shaft as a friction shaft. 
     Preferably, a fixing hole or fixing groove is disposed on an end face of the drive element adjacent to the spring, wherein the fixing portion of the spring is received in the fixing hole or fixing groove. 
     In preferred embodiments, the one-way damping structure further comprises an annular bushing, an internal wall defining an opening of which is formed as the friction force generation member, wherein the friction torque is generated by the slide of an outer diameter surface of the annular portion relative to the internal wall defining the opening of the annular bushing. That is to say, the friction force generation member is the internal wall defining the opening of the annular bushing as an internal wall defining a friction hole. 
     Preferably, the outer diameter surface of the annular portion and the internal wall defining the opening of the annular bushing are in an interference fit manner. 
     In preferred embodiments, the one-way damping structure further comprises a protruding structure independent of the drive element, wherein the fixing portion is fixed to the protruding structure, wherein the drive element comprises a protruding annulus, which is formed as the friction force generation member, and wherein the annular portion is around on the annulus and the friction torque is generated by the slide of the annular portion relative to the annulus. That is to say, the friction force generation member is the annulus as a friction shaft. 
     Preferably, the protruding structure comprises at least one protuberance, wherein the fixing portion is fixed by a space groove enclosed by the protuberance. 
     Preferably, a receiving groove is defined by the annulus and a peripheral edge of the drive element, wherein the annular portion is received in the receiving groove and is around on the annulus in an interference fit manner. 
     In preferred embodiments, the one-way damping structure further comprises a bearing structure independent of the drive element, which is formed as the friction force generation member, wherein the annular portion is around on the bearing structure in an interference fit manner such that the friction torque is generated by the slide of the annular portion relative to the bearing structure. That is to say, the friction force generation member is the bearing structure as a friction shaft. 
     Preferably, the one-way damping structure comprises an installation shaft, wherein the drive element is around on the installation shaft, and wherein a surface of the bearing structure facing the drive element is matched with a surface of the drive element facing the bearing structure so as to support the installation shaft. 
     In preferred embodiments, the one-way damping structure further comprises a bushing structure connected to the drive element in an anti-torsion manner, wherein the fixing portion is clamped by the bushing structure, wherein the annular portion is tightly installed in a fixing groove, an inner cylindrical surface of which is formed as the friction force generation member, and wherein the friction torque is generated by the slide of an outer diameter surface of the annular portion relative to the inner cylindrical surface of the fixing groove. That is to say, the friction force generation member is the inner cylindrical surface of the fixed groove as an internal wall defining a friction hole. 
     Preferably, the bushing structure comprises a clamping structure and pins oppositely protruding from a body, wherein the bushing structure is connected to the drive element in virtue of the pins, and wherein the fixing portion is clamped in virtue of the clamping structure. 
     Preferably, the clamping structure comprises a fixing bump for clamping the fixing portion. 
     The adjustment assembly according to the present invention comprises the above-mentioned one-way damping structure. 
     Preferably, the adjustment assembly further comprises an output structure, an installation structure and a driver, wherein the one-way damping structure and the output structure are installed on the installation structure, and wherein the driver is connected to the output structure by the one-way damping structure. 
     Preferably, the output structure is connected to a height adjustment mechanism for a seat basin, wherein the adjustment assembly forms a seat height adjuster. 
     Preferably, the installation structure comprises a gearbox fixedly connected to a cover plate, wherein the one-way damping structure and the output structure are installed between the gearbox and the cover plate. 
     Preferably, the adjustment assembly further comprises a gasket disposed between the spring and the gearbox. 
     Preferably, the adjusting assembly further comprises an installation structure and a driver, wherein the one-way damping structure is installed on the installation structure, wherein the driver has a motor shaft, wherein the annular portion of the spring is around on the motor shaft in an interference fit manner such that the friction torque is generated by the slide of an internal wall defining the opening of the annular portion relative to the outer surface of the motor shaft. 
     Preferably, the installation structure comprises a gearbox fixedly connected to a cover plate, wherein the one-way damping structure is installed between the gearbox and the cover plate, wherein the gearbox has a fixing groove, and wherein the fixing portion of the spring is fixed to the fixing groove. 
     The seat height adjuster according to the present invention utilizes one-way damping properties in which the spring of the one-way damping structure generates different torques in different rotation directions. In combination with the traditional output structure and installation structure, the driver continues to stably defy a fixed load so as to work when the seat is adjusted downwards under the load, and the lifting ability is unaffected when the seat is adjusted upwards. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an exploded view of a one-way damping structure according to a first preferred embodiment of the present invention; 
         FIG.  2    is a side view of the one-way damping structure of  FIG.  1   ; 
         FIG.  3    is a cross-sectional view taken along line A-A of  FIG.  2   ; 
         FIG.  4    is a structural schematic diagram of the spring of  FIG.  1   ; 
         FIG.  5    is a first mating state diagram of the installation shaft and the spring of  FIG.  1   ; 
         FIG.  6    is a second mating state diagram of the installation shaft and the spring of  FIG.  1   ; 
         FIG.  7    is a side view of an adjustment assembly including the one-way damping structure of the first preferred embodiment according to the present invention; 
         FIG.  8    is a cross-sectional view taken along line B-B of  FIG.  7   ; 
         FIG.  9    is a first mating state diagram of the installation shaft and the spring of  FIG.  7   ; 
         FIG.  10    is a second mating state diagram of the installation shaft and the spring of  FIG.  7   ; 
         FIG.  11    is an exploded view of an annular bushing and a spring of a one-way damping structure according to the second preferred embodiment of the present invention; 
         FIG.  12    is an assembly schematic diagram of the annular bushing and spring of  FIG.  11   ; 
         FIG.  13    is a side view of  FIG.  12   ; 
         FIG.  14    is a cross-sectional view taken along line C-C of  FIG.  13   ; 
         FIG.  15    is a first mating state diagram of the annular bushing and the spring of  FIG.  11   ; 
         FIG.  16    is a second mating state diagram of the annular bushing and the spring of  FIG.  11   ; 
         FIG.  17    is a structural schematic diagram of a spring of a one-way damping structure according to a third preferred embodiment of the present invention; 
         FIG.  18    is a structural schematic diagram of a fixing structure of the one-way damping structure according to the third preferred embodiment of the present invention; 
         FIG.  19    is an assembly schematic diagram of the spring of  FIG.  17    and the fixing structure of  FIG.  18   ; 
         FIG.  20    is a structural schematic diagram of a helical gear of the one-way damping structure according to the third preferred embodiment of the present invention; 
         FIG.  21    is an assembly schematic diagram of the spring of  FIG.  17    and the helical gear of  FIG.  20   ; 
         FIG.  22    is a first mating state diagram of the spring of  FIG.  17    and the helical gear of  FIG.  20   ; 
         FIG.  23    is a second mating state diagram of the spring of  FIG.  17    and the helical gear of  FIG.  20   ; 
         FIG.  24    is a structural schematic diagram of a spring of a one-way damping structure according to a fourth preferred embodiment of the present invention; 
         FIG.  25    is a structural schematic diagram of a bearing structure of the one-way damping structure according to the fourth preferred embodiment of the present invention; 
         FIG.  26    is an assembly schematic diagram of the spring of  FIG.  24    and the bearing structure of  FIG.  25   ; 
         FIG.  27    is a structural schematic diagram of a gearbox with the one-way damping structure according to the fourth preferred embodiment of the present invention; 
         FIG.  28    is an assembly schematic diagram of the bearing structure of  FIG.  25    and the gearbox of  FIG.  27   ; 
         FIG.  29    is a structural schematic diagram of a helical gear of the one-way damping structure according to the fourth preferred embodiment of the present invention; 
         FIG.  30    is an assembly schematic diagram of the bearing structure of  FIG.  25    and the helical gear of  FIG.  29   ; 
         FIG.  31    is a first mating state diagram of the bearing structure of  FIG.  25    and the helical gear of  FIG.  29   ; 
         FIG.  32    is a second mating state diagram of the bearing structure of  FIG.  25    and the helical gear of  FIG.  29   ; 
         FIG.  33    is a structural schematic diagram of a spring of a one-way damping structure according to a fifth preferred embodiment of the present invention; 
         FIG.  34    is a first structural schematic diagram of a bushing structure of the one-way damping structure according to the fifth preferred embodiment of the present invention; 
         FIG.  35    is a second structural schematic diagram of the bushing structure of the one-way damping structure according to the fifth preferred embodiment of the present invention; 
         FIG.  36    is a structural schematic diagram of a helical gear of the one-way damping structure according to the fifth preferred embodiment of the present invention; 
         FIG.  37    is an assembly schematic diagram of the spring of  FIG.  33   , the bushing structure of  FIG.  34    and the helical gear of  FIG.  36   ; 
         FIG.  38    is a structural schematic diagram of a gearbox with the one-way damping structure according to the fifth preferred embodiment of the present invention; 
         FIG.  39    is an assembly schematic diagram of the spring of  FIG.  33    and the gearbox of  FIG.  38   ; 
         FIG.  40    is a first mating state diagram of the spring of  FIG.  33    and the bushing structure of  FIG.  34   ; 
         FIG.  41    is a second mating state diagram of the spring of  FIG.  33    and the bushing structure of  FIG.  34   ; 
         FIG.  42    is a schematic diagram of a first wire of the spring according to the present invention; 
         FIG.  43    is a schematic diagram of a second wire of the spring according to the present invention; 
         FIG.  44    is a side view of an adjustment assembly including a one-way damping structure according to yet another preferred embodiment of the present invention; 
         FIG.  45    is a structural schematic diagram of the one-way damping structure of  FIG.  44   ; 
         FIG.  46    is a cross-sectional view taken along line D-D of  FIG.  44    showing a fixing groove on a gearbox for fixing the spring. 
     
    
    
     DESCRIPTION OF THE ENABLING EMBODIMENT 
     In conjunction with the accompanying drawings, preferred embodiments of the present invention are given and described in detail below. 
     As shown in  FIG.  1   , a one-way damping structure  1  according to a first preferred embodiment of the present invention comprises a spring  11 , a drive element  12  and an installation shaft  13 , wherein the spring  11  and the drive element  12  are around on the installation shaft  13 . Specifically, the drive element  12  comprises a worm gear  121  meshed with a helical gear  122 , wherein the spring  11  and the helical gear  122  are around on the installation shaft  13 , as shown in  FIGS.  2 - 3   . 
     As shown in  FIG.  4   , the spring  11  comprises a fixing portion  111 , a connecting portion  112  and an annular portion  113 , wherein the connecting portion  112  is located between the fixing portion  111  and the annular portion  113  and connects the fixing portion  111  to the annular portion  113 . In particular, the annular portion  113  comprises at least half a turn spirally extending in a circumferential direction and defining a spring opening. 
     Returning to  FIG.  1   , the helical gear  122  comprises a fixing hole  122   a,  a connecting groove  122   b  and a receiving hole  122   c  disposed on the end face adjacent to the spring  11 . With reference to  FIGS.  2 - 3   , the fixing portion  111 , the connecting portion  112  and the annular portion  113  of the spring  11  are respectively received in the fixing hole  122   a,  the connecting groove  122   b  and the receiving hole  122   c  of the helical gear  122 . 
     In particular, the annular portion  113  of the spring  11  is around on the installation shaft  13  in an interference fit manner. As such, one end of the spring  11  is fixed to the helical gear  122 , and the other end is around on the installation shaft  13  in the interference fit manner. When the helical gear  122  is rotated around an axis L of the installation shaft  13  under an external force, the fixing portion  111  of the spring  11  is rotated accordingly, and the annular portion  113  of the spring  11  slides relative to the installation shaft  13  to generate friction torque. It should be understood that the installation shaft  13  may be fixed or rotated around the axis L. As long as the rotation of the installation shaft  13  is asynchronous with the rotation of the helical gear  122  to produce a relative slide, the friction torque is generated. 
     According to the characteristics of the spring structure, the spring becomes tighter when rotated in a helical direction, and the spring becomes looser when rotated in a reverse helical direction. As shown in  FIG.  5   , when the force of F_cw in the reverse helical direction is applied to the spring  11  by the helical gear  122 , the annular portion  113  of the spring  11  is rotated in the CW direction relative to the installation shaft  13 , and a relatively small friction torque is generated by the slide of the spring  11  relative to the installation shaft  13 . As shown in  FIG.  6   , when the force of F_ccw in the helical direction is applied to the spring  11  by the helical gear  122 , the annular portion  113  of the spring  11  is rotated in the CCW direction relative to the installation shaft  13 , and a rated friction torque is generated by the slide of the spring  11  relative to the installation shaft  13 . The rated friction torque can be designed and controlled as needed. As such, the one-way damping structure  1  can provide one-way damping effect, wherein different friction torques in different directions are generated by the slide of the spring  11  relative to the installation shaft  13  when the spring  11  is rotated in different directions relative to the installation shaft  13 . 
     As shown in  FIGS.  7 - 8   , an adjustment assembly according to the present invention comprises the one-way damping structure  1  of the first preferred embodiment, an output structure  2 , an installation structure  3  and a driver  4 , wherein the one-way damping structure  1  and the output structure  2  are installed on the installation structure  3 , and the driver  4  is connected to the output structure  2  by the one-way damping structure  1 . In the present embodiment, the output structure  2  is connected to a height adjustment mechanism for a seat basin, so as to adjust the seat upwards and downwards by the driver  4 . Thus, the adjustment assembly forms a seat height adjuster. 
     The installation structure  3  comprises a gearbox  31  fixedly connected to a cover plate  32 , wherein the one-way damping structure  1  and the output structure  2  are generally installed between the gearbox  31  and the cover plate  32 . 
     The driver  4  is a motor, which is connected to a worm  121 . 
     In particular, the adjustment assembly further comprises a gasket  5  around on the installation shaft  13  and disposed between the spring  11  and the gearbox  31 . In the present embodiment, the gasket  5  is a corrugated gasket. It should be understood that the gasket  5  can be a similar elastic gasket, which is used to adjust the axial gap between the spring  11  and the gearbox  31  along the installation shaft  13  on one hand, and to prevent the spring  11  from axially moving off the installation shaft  13  on the other hand. The gasket  5  can also be a flat gasket or a gasket with other structural shapes or even be omitted, when there is another fixing device for the spring  11  along the axial direction of the installation shaft  13  and there is another structure for adjusting the axial gap between the spring  11  and the gearbox  31 . 
     As such, during the adjustment process of the seat height adjuster according to the present embodiment, the worm  121  is driven to be rotated by the driver  4 , and the motion and power are transmitted to the helical gear  122 , so that the helical gear  122  is rotated around the installation shaft  13 . Since the fixing portion  111  of the spring  11  is fixedly connected to the helical gear  122  and the annular portion  113  is around on the installation shaft  13  in an interference fit manner, resistance is provided by the rotation of the annular portion  113  of the spring  11  relative to the installation shaft  13  when the helical gear  122  is rotated relative to the installation shaft  13 . Once the resistance provided by the spring  11  is overcome by the helical gear  122 , the motion and power are transmitted to the output structure  2 , thereby to adjust the seat upwards and downwards. 
     As shown in  FIG.  9   , when the seat is adjusted downwards, the helical gear  122  drives the annular portion  113  of the spring  11  to rotate in the CCW direction relative to the installation shaft  13 , and a set frictional resistance torque Tf_CW in the CW direction is generated between the spring  11  and the installation shaft  13 . The frictional resistance torque Tf_CW drives the meshing tooth surface of the helical gear  122  in close contact with the meshing tooth surface of the worm  121 , so that the entire seat is adjusted downwards steadily and slowly. 
     As shown in  FIG.  10   , when the seat is adjusted upwards, the helical gear  122  drives the annular portion  113  of the spring  11  to rotate in the CW direction relative to the installation shaft  13 , and a relatively small frictional resistance torque Tf_CCW in the CCW direction is generated between the spring  11  and the installation shaft  13 . Compared with the frictional resistance torque Tf_CW, the frictional resistance torque Tf_CCW is very small and negligible. Thus, no effect is caused in the seat lifting direction, and the seat lifting ability and the seat lifting speed are essentially unaffected. 
     As such, according to the above two processes, for the one-way damping structure  1  of the seat height adjuster according to the present embodiment, on one hand, the internal resistance of the system is increased when the seat is adjusted downwards so that the entire downward adjustment is smooth, and on the other hand, the internal resistance is negligible when the seat is adjusted upwards so that the lifting ability of the seat is unaffected. In a word, the seat height adjuster according to the present embodiment utilizes one-way damping properties in which the spring  11  of the one-way damping structure  1  generates different torques in different rotation directions. In combination with the traditional output structure  2  and the installation structure  3 , the driver  4  continues to stably defy a fixed load so as to work when the seat is adjusted downwards under the load, and the lifting ability is unaffected when the seat is adjusted upwards. Specifically, when the seat is adjusted downwards under the load, the driver  4  continues to work stably, and the internal resistance of the entire system is stable, the problem of abnormal noise and unstable operation caused by the unstable or too small internal resistance internal resistance is overcome. Only the downward adjustment is affected by the one-way damping structure  1 , and the upward adjustment of the seat and the lifting ability are unaffected. Since the damping is increased during the downward adjustment of the seat, the downward adjustment is slowed down, and the difference between the speeds of the upward and downward adjustments becomes smaller. 
     In the first embodiment, the annular portion  113  of the spring  11  of the one-way damping structure  1  is around on the installation shaft  13  in an interference fit manner, such that the friction torque is generated by the slide of the internal wall defining the opening of the annular portion  113  of the spring  11  relative to the outer surface of the installation shaft  13 . Differently, the one-way damping structure  1 ′ according to the second preferred embodiment of the present invention further comprises an annular bushing  14 ′, the friction torque is generated by the slide of the outer diameter surface of the annular portion  113 ′ of the spring  11 ′ relative to the internal wall defining the opening of the annular bushing  14 ′, as shown in  FIGS.  11 - 14   . In particular, the outer diameter surface of the annular portion  113 ′ of the spring  11 ′ and the internal wall defining the opening of the annular bushing  14 ′ are in an interference fit manner. 
     As shown in  FIG.  15   , when the spring  11 ′ is rotated in the CW direction relative to the annular bushing  14 ′ under the driving force F_cw, a rated friction torque in the CCW direction is generated by the slide of the outer diameter surface of the annular portion  113 ′ of the spring  11 ′ relative to the internal wall defining the opening of the annular bushing  14 ′. The rated friction torque can be designed and controlled as needed. 
     As shown in  FIG.  16   , when the spring  11 ′ is rotated in the CCW direction relative to the annular bushing  14 ′ under the driving force F_ccw, a relatively small friction torque is generated due to the outer diameter surface of the annular portion  113 ′ of the spring  11 ′ gradually disengaging from the internal wall defining the opening of the annular bushing  14 ′. 
     As such, the one-way damping effect is provided, wherein different friction torques in different directions are generated when the spring  11 ′ is rotated in different directions under the external force. The damping direction can be switched by adjusting the helical direction (right-handed to left-handed) of the spring  11 ′. 
     In the first embodiment, the fixing portion  111  of the spring  11  of the one-way damping structure  1  is fixedly connected to the helical gear  122 , and the annular portion  113  of the spring  11  is around on the installation shaft  13  in an interference fit manner, such that the friction torque is generated by the slide of the annular portion  113  relative to the installation shaft  13 . Differently, the one-way damping structure  1 ″ according to the third preferred embodiment of the present invention further comprises a protruding structure  15 ″, wherein one end of the spring  11 ″ is fixed to the protruding structure  15 ″, and the other end is cooperated with the helical gear  122 , as shown in  FIGS.  17 - 21   . 
     As shown in  FIG.  17   , the shape of the spring  11 ″ is slightly different from the spring  11  of the first embodiment, but still comprises a fixing portion  111 ″, a connecting portion  112 ″ and an annular portion  113 ″, wherein the connecting portion  112 ″ is located between the fixing portion  111 ″ and the annular portion  113 ″ and connects the fixing portion  111 ″ to the annular portion  113 ″. In particular, the annular portion  113 ″ comprises at least half a turn spirally extending in a circumferential direction and defining a spring opening. 
     As shown in  FIG.  18   , the protruding structure  15 ″ comprises the protuberances  151 ″,  152 ″,  153 ″,  154 ″ on the gearbox  31 ″, and the fixing portion  111 ″ and the connecting portion  112 ″ of the spring  11 ″ are fixed by the space groove enclosed by the protuberances  151 ″,  152 ″,  153 ″,  154 ″, as shown in  FIG.  19   . 
     As shown in  FIG.  20   , unlike the helical gear  122  of the first embodiment, which has a fixing hole  122   a,  a connecting groove  122   b  and a receiving hole  122   c,  the helical gear  122 ″ of the present embodiment comprises a protruding annulus  122   d″.  A receiving groove  122   e″  is defined by the annulus  122   d″  and the peripheral edge of the helical gear  122 ″. The annular portion  113 ″ of the spring  11 ″ is around on the annulus  122   d″  in an interference fit manner and is received in the receiving groove  122   e″,  as shown in  FIG.  21   . As such, the friction torque is generated by the slide of the annular portion  113 ″ of the spring  11 ″ relative to the annulus  122   d″.    
     As shown in  FIG.  22   , when the seat is adjusted downwards, the annulus  122   d″  (i.e., the helical gear  122 ″) is rotated in the CCW direction relative to the annular portion  113 ″ of the spring  11 ″, and a set frictional resistance torque Tf_CW in the CW direction is generated between the spring  11 ″ and the annulus  122   d″.  The frictional resistance torque Tf_CW drives the meshing tooth surface of the helical gear  122 ″ in close contact with the meshing tooth surface of the worm, so that the entire seat is adjusted downwards steadily and slowly. 
     As shown in  FIG.  23   , when the seat is adjusted upwards, the annulus  122   d″  (i.e., the helical gear  122 ″) is rotated in the CW direction relative to the annular portion  113 ″ of the spring  11 ″, and a relatively small frictional resistance torque Tf_CCW in the CCW direction is generated between the spring  11 ″ and the annulus  122   d″.  Compared with the frictional resistance torque Tf_CW, the frictional resistance torque Tf_CCW is very small and negligible. Thus, no effect is caused in the seat lifting direction, and the seat lifting ability and the seat lifting speed are essentially unaffected. 
     As such, according to the above two processes, for the one-way damping structure  1 ″ of the seat height adjuster according to the present embodiment, on one hand, the internal resistance of the system is increased when the seat is adjusted downwards so that the entire downward adjustment is smooth, and on the other hand, the internal resistance is negligible when the seat is adjusted upwards so that the lifting ability of the seat is unaffected. 
     In the first embodiment, the annular portion  113  of the spring  11  of the one-way damping structure  1  is around on the installation shaft  13  in an interference fit manner, such that the friction torque is generated by the slide of the annular portion  113  relative to the installation shaft  13 . Differently, the one-way damping structure  1 ′″ according to the fourth preferred embodiment of the present invention further comprises a bearing structure  16 ′″, which is cooperated with the annular portion  113 ′″ of the spring  11 ′″, as shown in  FIGS.  24 - 30   . 
     As shown in  FIG.  24   , the shape of the spring  11 ′″ is slightly different from the spring  11  of the first embodiment, but still comprises a fixing portion  111 ′″, a connecting portion  112 ′″ and an annular portion  113 ′″, wherein the connecting portion  112 ′″ is located between the fixing portion  111 ′″ and the annular portion  113 ′″ and connects the fixing portion  111 ′″ to the annular portion  113 ′″. In particular, the annular portion  113 ′″ comprises at least half a turn spirally extending in a circumferential direction and defining a spring opening. 
     As shown in  FIG.  25   , the bearing structure  16 ′″ has an outer peripheral wall  161 ′″, and the annular portion  113 ′″ of the spring  11 ′″ is around on the outer peripheral wall  161 ′″ in an interference fit manner, as shown in  FIG.  26   . A through hole  162 ′″ is disposed in the middle of the bearing structure  16 ′″ for the installation shaft to pass through, and a plurality of anti-torsion structures  163 ′″ are disposed around the through hole  162 ′″. In addition, a sliding surface  164 ′″ is formed by the end face of the bearing structure  16 ′″ which is opposite to the anti-torsion structures  163 ′″, as shown in  FIG.  26   . 
     As shown in  FIG.  27   , the gearbox  31 ′″ has an anti-torsion structure  311 ′″ which is cooperated with the anti-torsion structures  163 ′″ of the bearing structure  16 ′″, as shown in  FIG.  28   . It should be understood that such anti-torsion structure is disposed to provide that the bearing structure  16 ′″ can be successfully pressed into the gearbox  31 ′″ and can be fixed in position without relative rotation, which can be replaced with other anti-torsion features to provide the similar function as required. The bearing structure  16 ′″ can be integrally formed on the gearbox  31 ′″. 
     As shown in  FIG.  29   , unlike the helical gear  122  of the first embodiment, which has a connecting groove  122   b  and a receiving hole  122   c,  the helical gear  122 ′″ of the present embodiment only comprises the fixing hole  122   a′″,  and the fixing portion  111 ′″ of the spring  11 ′″ is inserted into the fixing hole  122   a′″.  A sliding surface  122   f′″  is formed by the end face facing the spring  11 ′″. It should be understood that the structure for fixing the fixing portion  111 ′″ of the spring  11 ′″ is not necessarily a fixing hole, it may be a groove or other features for the fixing portion  111 ′″, as long as one end of the spring  11 ′″ can be fixed on the helical gear  122 ′″. 
     As shown in  FIG.  30   , in the assembled state, the annular portion  113 ′″ of the spring  11 ′″ is around on the outer peripheral wall  161 ′″ of the bearing structure  16 ′″ in an interference fit manner, such that the friction torque is generated by the slide of the annular portion  113 ′″ of the spring  11 ′″ relative to the bearing structure  16 ′″. The installation shaft is inserted into the through hole  162 ′″ of the bearing structure  16 ′″. The sliding surface  122   f′″  of the helical gear  122 ′″ is matched with the sliding surface  164 ′″ of the bearing structure  16 ′″ to support the installation shaft. 
     As shown in  FIG.  31   , when the seat is adjusted downwards, the bearing structure  16 ′″ is rotated in the CW direction relative to the annular portion  113 ′″ of the spring  11 ′″, and a frictional resistance torque Tf_CCW in the CCW direction is generated between the annular portion  113 ′″ and the bearing structure  16 ′″. The frictional resistance torque Tf_CCW drives the meshing tooth surface of the helical gear  122 ′″ in close contact with the meshing tooth surface of the worm, so that the entire seat is adjusted downwards steadily and slowly. 
     As shown in  FIG.  32   , when the seat is adjusted upwards, the bearing structure  16 ′″ is rotated in the CCW direction relative to the annular portion  113 ′″ of the spring  11 ′″, and a frictional resistance torque Tf_CW in the CW direction is generated between the annular portion  113 ′″ and the bearing structure  16 ′″. Compared with the frictional resistance torque Tf_CCW, the frictional resistance torque Tf_CW is very small and negligible. Thus, no effect is caused in the seat lifting direction, and the seat lifting ability and the seat lifting speed are essentially unaffected. 
     As such, according to the above two processes, for the one-way damping structure  1 ′″ of the seat height adjuster according to the present embodiment, on one hand, the internal resistance of the system is increased when the seat is adjusted downwards so that the entire downward adjustment is smooth, and on the other hand, the internal resistance is negligible when the seat is adjusted upwards so that the lifting ability of the seat is unaffected. 
     In the first embodiment, the fixing portion  111  of the spring  11  of the one-way damping structure  1  is fixedly to the helical gear  122 , and the annular portion  113  of the spring  11  is around on the installation shaft  13  in an interference fit manner, such that the friction torque is generated by the slide of the annular portion  113  relative to the installation shaft  13 . Differently, the one-way damping structure  1 ″″ according to the fifth preferred embodiment of the present invention further comprises a bushing structure  17 ″″, which is cooperated with one end of the spring  11 ″″, as shown in  FIGS.  33 - 38   . 
     As shown in  FIG.  33   , the shape of the spring  11 ″″ is slightly different from the spring  11  of the first embodiment, but still comprises a fixing portion  111 ″″, a connecting portion  112 ″″ and an annular portion  113 ″″, wherein the connecting portion  112 ″″ is located between the fixing portion  111 ″″ and the annular portion  113 ″″ and connects the fixing portion  111 ″″ to the annular portion  113 ″″. In particular, the annular portion  113 ″″ comprises at least half a turn spirally extending in a circumferential direction and defining a spring opening. 
     As shown in  FIG.  34   , the bushing structure  17 ″″ has a clamping structure  172 ″″ and pins  173 ″″ oppositely protruding from a body  171 ″″. In particular, the clamping structure  172 ′″ has a fixing bump  172   a″″,  and the pins  173 ′″ are three fixing feet evenly distributed, as shown in  FIG.  35   . 
     As shown in  FIG.  36   , unlike the helical gear  122  of the first embodiment, which has a connecting groove  122   b  and a receiving hole  122   c,  the helical gear  122 ″″ of the present embodiment only comprises the fixing hole  122   a″″,  and the pins  173 ″″ of the bushing structure  17 ″″ are inserted into the fixing hole  122   a″″.  It should be understood that the structure for fixing the pins  173 ″″ of the bushing structure  17 ″″ is not necessarily a fixing hole, it may be a groove or other features for the pins  173 ″″, as long as the bushing structure  17 ″″ can be fixed on the helical gear  122 ″″. Once the bushing structure  17 ″″ is fixed to the helical gear  122 ″″ in an anti-torsion manner, the spring  11 ″″ is fixed to the bushing structure  17 ″″ in virtue of the clamping structure  172 ″″. In particular, the fixing portion  111 ″″ is clamped and fixed by the fixing bump  172   a″″,  as shown in  FIG.  37   . 
     As shown in  FIG.  38   , the gearbox  31 ″″ has a gearbox slot  312 ″″, and the spring  11 ″″ is tightly installed on the inner cylindrical surface of the gearbox slot  312 ″″. That is to say, the spring  11 ″″ has a radially outwardly expanding pre-tightened force, such that the friction torque is generated by the slide of the outer diameter surface of the annular portion  113 ″″ of the spring  11 ″″ relative to the inner cylindrical surface of the gearbox groove  312 ″″, as shown in  FIG.  39   . 
     As shown in  FIG.  40   , when the seat is adjusted downwards, the helical gear  122 ″″ drives the annular portion  113 ″″ of the spring  11 ″″ to rotate in the CW direction relative to the gearbox  31 ″″ by the bushing structure  17 ″″, and a frictional resistance torque Tf_CCW in the CCW direction is generated between the outer diameter surface of the annular portion  113 ″″ of the spring  11 ″″ and the inner cylindrical surface of the gearbox groove  312 ″″. The frictional resistance torque Tf_CCW drives the meshing tooth surface of the helical gear  122 ″″ in close contact with the meshing tooth surface of the worm, so that the entire seat is adjusted downwards steadily and slowly. 
     As shown in  FIG.  41   , when the seat is adjusted upwards, the helical gear  122 ″″ drives the annular portion  113 ″″ of the spring  11 ″″ to rotate in the CCW direction relative to the gearbox  31 ″″ by the bushing structure  17 ″″, and a frictional resistance torque Tf_CW in the CW direction is generated between the outer diameter surface of the annular portion  113 ″″ of the spring  11 ″″ and the inner cylindrical surface of the gearbox groove  312 ″″. Compared with the frictional resistance torque Tf_CCW, the frictional resistance torque Tf_CW is very small and negligible. Thus, no effect is caused in the seat lifting direction, and the seat lifting ability and the seat lifting speed are essentially unaffected. 
     As such, according to the above two processes, for the one-way damping structure  1 ″″ of the seat height adjuster according to the present embodiment, on one hand, the internal resistance of the system is increased when the seat is adjusted downwards so that the entire downward adjustment is smooth, and on the other hand, the internal resistance is negligible when the seat is adjusted upwards so that the lifting ability of the seat is unaffected. 
     It should be understood that the wire for the springs  11 ,  11 ′,  11 ′″,  11 ″″ according to the present invention can be in the circular cross-section shown in  FIG.  42   , or in the rectangular cross-section shown in  FIG.  43   , or in other special-shaped cross-section. The fixing way for the springs  11 ,  11 ′,  11 ′″,  11 ″″ is not limited to above embodiments, as long as at least one end is fixed. The friction torque is generated by the slide of the springs  11 ,  11 ′,  11 ′″,  11 ″″ relative to the paired shaft. On the contacting surfaces, the positive pressure can be guaranteed by the interference fit during assembly, or can be generated by other methods, such as the spring connecting to other adjustment mechanisms. When the friction resistance is required, the spring can be adjusted manually or automatically such that the spring can be tightened to generate a positive pressure between the spring and the shaft, in order to generate the friction resistance. When the friction resistance is not required, the spring can be adjusted manually or automatically such that the spring can be loosed to release the positive pressure between the spring and the shaft, and then the frictional resistance disappears. It should be understood that by controlling this adjustment method, the positive pressure between the spring and the shaft can be adjusted, and thus the damping structure with variable resistances can be provided, that is, a one-way variable damping mechanism. The direction of one-way damping structure can be switched by adjusting the helical direction of the springs  11 ,  11 ′,  11 ′″,  11 ″″. The friction torque of the springs  11 ,  11 ′,  11 ′″,  11 ″ can be adjusted by the number of turns of the spring, or by the spring materials, or by the magnitude of interference between the spring and the shaft or the internal wall defining the opening. 
     It should be understood that the one-way damping structure  1 ,  1 ′,  1 ′″,  1 ″″ according to the present invention comprises the most basic damping generating unit: a spring, a friction shaft or an internal wall defining a friction hole, wherein the friction shaft may be a shaft, or an annular boss or a sleeve, as long as providing the outer cylindrical surface for matching with the spring. Also, the outer cylindrical surface can be continuous or discontinuous. The internal wall defining the friction hole can be the internal wall defining the opening, or the annular groove surface, as long as providing the inner cylindrical surface for matching with the spring. Also, the inner cylindrical surface can be continuous or discontinuous. For the one-way damping structure  1 ,  1 ′,  1 ′″,  1 ″″, the matching units, such as the drive unit, the spring fixing unit, etc. can be changed in different fields. The fixing way for the spring and the drive element or the fixing element is not limited to above mentioned methods, as long as the structural features provide the corresponding function, which should be included in the protection scope of the invention. For the one-way damping structure  1 ,  1 ′,  1 ′″,  1 ″″, the damping force can be generated by a dynamic friction resistance. Similarly, static friction resistance can also be used in transmission units or other mechanisms. For example, a static friction force is generated when there is a tendency of the slide of the spring relative to the friction shaft or the internal wall defining the friction hole, and a certain friction force is generated in a single direction. The one-way damping structure  1 ,  1 ′,  1 ′″,  1 ″″ can be applied to application fields such as load protection. Such damping structure unit  1 ,  1 ′,  1 ′″,  1 ″″ can be formed as a one-way locking mechanism to form one-way load protection in one-way torque testing and other fields through the specific torque design according to the one-way damping characteristics. The one-way damping structure  1 ,  1 ′,  1 ′″,  1 ″″ can be made into the form of damping bearings in other engineering fields. It should be understood that a two-way identical damping mechanism, a two-way different damping mechanism, one-way locking and one-way damping mechanism, two-way locking mechanism, one-way variable damping mechanism, and two-way variable damping mechanism, etc. can be formed from the one-way damping structure  1 ,  1 ′,  1 ′″,  1 ″″ through the specific torque design and the combination of the same or different types of base units of the one-way damping mechanism. 
     It should be understood that the one-way damping structure  1 ,  1 ′,  1 ′″,  1 ″″ according to the present invention is not limited to be applied to seat height adjustment products, but can also be applied to other similar adjustment mechanisms, such as seat backrest adjustment unit, etc. The one-way damping structure  1 ,  1 ′,  1 ′″,  1 ″″ can be used not only in electric adjustment products, but also in manual adjustment products. The one-way damping structure  1 ,  1 ′,  1 ′″,  1 ″″ is not limited to seat transmission products, but also for the production of measuring tools, and other products in other fields. The one-way damping structure  1 ,  1 ′,  1 ′″,  1 ″″ is not limited to be acted on the helical gear, but also be fixed on other structural ends with relative motion, such as the motor shaft or the end of the output gear shaft. For example, for the seat height adjustment product, the one-way damping structure can be applied to the matching between the motor rotating shaft and the spring, and also can be applied to the output gear shaft of the seat to achieve a similar or better product effect. 
     As shown in  FIGS.  44 - 46   , the annular portion  1130  of the spring  110  of the one-way damping structure of the adjustment assembly according to yet another embodiment of the present invention is around on the motor shaft  410  of the driver  40 , and the fixing portion  1110  of the spring  110  is fixed to the fixing groove of the gearbox  310 . When the motor shaft  410  is rotated, a one-way friction force is generated between the internal wall defining the opening of the annular portion  1130  and the outer surface of the motor shaft  410 , in order to provide the one-way damping characteristic. It should be understood that the direction of the friction force can be adjusted according to the helical direction and installation direction of the spring. 
     The foregoing description refers to preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Various changes can be made to the foregoing embodiments of the present invention. That is to say, all simple and equivalent changes and modifications made in accordance with the claims of the present invention and the content of the description fall into the protection scope of the patent of the present invention. What is not described in detail in the present invention is conventional technical content.