Reclining device

Abstract

To provide a reclining device which prevents occurrence of an abnormal noise.SOLUTION: A reclining device includes: a first arm mounted on a seat cushion; a second arm mounted on a seat back and supported rotatably with respect to the first arm; a first energization member one end of which is engaged with the second arm while the seat back moves between a backward inclination position and a forward inclination position so as to energize the seat back forward; a second energization member one end of which is engaged with the second arm while the seat back moves between the forward inclination position and a predetermined position so as to energize the seat back backward with an energizing force smaller than the energizing force of the first energization member while the seat back moves between the forward inclination position and the predetermined position which is located between the forward inclination position and the backward inclination position; and an engagement member which is engaged with the one end of the second energization member while the seat back moves between the predetermined position and the backward inclination position.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a reclining device for a seat.

Background Art

[0002] There is known a reclining device that tilts a seat back, such as a vehicle seat, in the front-rear direction. For example, in Patent Document 1 below, in addition to a return spring that biases the seat back forward, when the seat back tilts forward from a predetermined position, a brake spring that biases the seat back rearward by engaging the outer end of the brake spring with the arm of the seat back is used to adjust the forward tilt speed of the seat back.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the case of the device of Patent Document 1 above, if the structure is such that the outer end of the brake spring is engaged with the arm only when the seat back is in a part of its movable range, a state where the outer end of the brake spring is not engaged occurs. Thus, when one end of the spring is in a non-engaged state, unexpected vibrations or the like may occur in the spring due to the engagement of the one end with the arm or other external factors, and abnormal noises may occur.

[0005] In consideration of the above problems, an object of the present disclosure is to provide a reclining device that prevents the generation of abnormal noises.

Means for Solving the Problems

[0006] To achieve the above object, a reclining device according to a first aspect of the present disclosure includes a first arm attached to a seat cushion, a second arm attached to a seat back and rotatably supported with respect to the first arm, and a first biasing member having one end engaged with the second arm for biasing the seat back forward while the seat back moves between a reclined position where the seat back is reclined with respect to the seat cushion and a forward inclined position where the seat back is inclined forward with respect to the seat cushion. A second biasing member having one end engaged with the second arm for biasing the seat back rearward with a biasing force smaller than that of the first biasing member while the seat back moves between the forward inclined position and a predetermined position between the forward inclined position and the reclined position. And an engaging member engaged with the one end of the second biasing member while the seat back moves between the predetermined position and the reclined position.

[0007] In such a reclining device, since one end of the second biasing member is always engaged with either the second arm or the engaging member, it can be ensured that a state where one end of the second biasing member is not engaged does not occur.

[0008] A reclining device according to a second aspect of the present disclosure is the reclining device according to the first aspect of the present disclosure, wherein the other end of the first biasing member, the other end of the second biasing member, and one end of the engaging member are attached to an attachment member fixed to the first arm.

[0009] In such a reclining device, by attaching each biasing member and the engaging member to a single member, the alignment of each member can be easily performed.

Advantages of the Invention

[0010] According to the reclining device of the present disclosure, since one ends of the first and second biasing members are always engaged regardless of the position of the seat back, it becomes possible to provide a reclining device that prevents the generation of abnormal noises.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. In the following, the range necessary for the description for achieving the object of the present disclosure is schematically shown, and mainly the range necessary for the description of the corresponding part of the present disclosure will be described, and parts for which the description is omitted are assumed to be based on known techniques. In the drawings, the same or corresponding members are denoted by the same or similar reference numerals, and duplicate descriptions are omitted.

[0013] FIG. 1 is a side view showing a state in which an example of a reclining device according to an embodiment of the present disclosure is adopted in a seat. As shown in FIG. 1, the reclining device 10 according to the present embodiment can be applied to a vehicle seat, particularly a seat such as a front seat of a passenger car. This seat 1 includes at least a seat cushion 2 that forms a seating surface on which a seated person sits and supports the buttocks and thighs of the seated person, and a seat back 3 that forms a backrest portion and supports the back of the seated person. The seat back 3 may be rotatably connected to the seat cushion 2 via a rotation axis 4. Thereby, the seat back 3 is in a position rotated forward, that is, a forward tilt position (also referred to as the "most forward tilt position") where the upper surface of the seat cushion 2 and the front surface of the seat back 3 are closest to each other, and a position rotated backward, that is, a rear tilt position (also referred to as the "most rear tilt position") where the upper surface of the seat cushion 2 and the front surface of the seat back 3 are farthest apart, and is rotatable therebetween. The reclining device 10 according to the present embodiment may be a mechanism for realizing the rotation operation of the seat back 3 described above. In FIG. 1, components other than the reclining device 10 are shown by dotted lines or omitted. The X direction indicated by the arrow in FIG. 1 represents the left-right direction (width direction) of the seat 1, the Y direction similarly represents the front-rear direction of the seat 1, and the Z direction represents the up-down direction of the seat 1.

[0014] FIG. 2 is a perspective view of a main part of the reclining device shown in FIG. 1. Further, FIG. 3 is an exploded perspective view of the reclining device shown in FIG. 2. As shown in FIGS. 1 to 3, the reclining device 10 according to the present embodiment includes a lower arm 20 as an example of a first arm attached to the seat cushion 2, an upper arm 30 as an example of a second arm attached to the seat back 3, and first and second biasing springs (corresponding to the first and second biasing members) 40, 50 disposed near the connecting portion between the lower arm 20 and the upper arm 30.

[0015] The lower arm 20 may be composed of a flat metal plate directly or indirectly attached to the seat cushion 2. This lower arm 20 can be attached to a part of the seat cushion 2, for example, a side frame of a seat cushion frame (not shown), and for this attachment, a well-known attachment structure, such as fixing with screws, can be adopted. A through hole into which the rotation shaft 4 can be inserted may be formed at a substantially central portion of the lower arm 20. Further, a latching bracket (corresponding to the attachment member) 21 for supporting one ends of the first and second biasing springs 40 and 50 described later may be fixed to the surface of the lower arm 20 on the side opposite to the surface facing the upper arm 30. The specific structure of this latching bracket 21 will be described later. In the present embodiment, the lower arm 20 is exemplified as the first arm, but the first arm is not limited to the lower arm 20 as long as it is a member attached to the seat cushion 2, and may be, for example, a part of the seat cushion frame (for example, the above-mentioned side frame).

[0016] The upper arm 30 may be composed of a long metal plate along the side surface of the seat back 3, directly or indirectly attached to the seat back 3. This upper arm 30 can be attached to a part of the seat back 3, for example, a side frame of a seat back frame (not shown), and for this attachment, a well-known attachment structure, such as fixing with screws as in the above-mentioned lower arm 20, can be adopted. A through hole into which the rotation shaft 4 can be inserted may be formed on one surface of the proximal end side of the upper arm 30. By inserting the rotation shaft 4, the upper arm 30 can rotate about the rotation shaft 4 with respect to the lower arm 20. In the present embodiment, the upper arm 30 is exemplified as the second arm, but the second arm is not limited to the upper arm 30 as long as it is a member attached to the seat back 3, and may be, for example, a part of the seat back frame (for example, the above-mentioned side frame).

[0017] A part of the surface of this upper arm 30 facing the lower arm 20, more specifically, at an intermediate position in the longitudinal direction of the upper arm 30, a first engaging bracket 31 that can engage with the first and second biasing springs 40 and 50 may be fixed. As shown in FIG. 3, this first engaging bracket 31 has a fixing piece 32 fixed to the upper arm 30 and an engaging piece 33 extending upright from one surface of the upper arm 30 in the outer (left) direction of the seat 1 (the -X direction in FIG. 2). The engaging piece 33 is such that one ends of the first and second biasing springs 40 and 50 can engage therewith. Specifically, both sides of the engaging piece 33 positioned in the front-rear direction can function as first and second engaging portions 34 and 35 that engage with one ends of the first and second biasing springs 40 and 50. This first engaging bracket 31 is connected such that the fixing piece 32 and the engaging piece 33 intersect each other and is configured as a substantially L-shaped metal piece when viewed from the front-rear direction.

[0018] Also, on the surface of the lower arm 20 facing the upper arm 30, a well-known recliner 5 for permitting or locking the rotation of the upper arm 30 and the seat back 3 may be fixed. As this recliner 5, for example, protrusions (not shown) are formed on the surface on the upper arm 30 side, and the rotation of the upper arm 30 and the seat back 3 may be controlled by these protrusions meshing with recesses (not shown) provided around a through-hole into which the rotation axis 4 of the upper arm 30 is inserted. As this recliner 5, a manual type or an electric type can be adopted. Further, in the reclining device 10, when the recliner 5 is, for example, of the manual type, an operation lever or the like (not shown) may be further included, and when it is of the electric type, a drive source, an actuator or the like (not shown) may be further included.

[0019] The first and second biasing springs 40 and 50 operate the seat back 3 in the front-rear direction with respect to the seat cushion 2 by their biasing forces. In the present embodiment, spiral springs formed by winding a long strip-shaped metal member are adopted for the first and second biasing springs 40 and 50. Although both the first and second biasing springs 40 and 50 can be configured as spiral springs, their biasing forces are adjusted such that the biasing force of the second biasing spring 50 is smaller than that of the first biasing spring 40. Then, the first and second biasing springs 40 and 50 configured as spiral springs can be arranged in parallel along one surface of the lower arm 20 so that the rotation shaft 4 is located in the space formed in their central portions.

[0020] The first biasing spring 40 is a spring body that functions to bias the seat back 3 forward (forward tilting direction). This first biasing spring 40 includes a first outer end (an example of one end of the first biasing spring) 41 located on the outer side in the circumferential direction and curved in a hook shape, a first inner end (an example of the other end of the first biasing spring) 42 located on the inner side in the circumferential direction and curved in a hook shape, and a first winding portion 43 connecting the first outer end 41 and the first inner end 42, and can be configured as a spiral spring. Among these, the first inner end 42 may be hooked at an arbitrary position of the lower arm 20, for example, on the latching bracket 21. Further, the first outer end 41 may be engaged with an arbitrary position of the upper arm 30, for example, with a first engaging portion 34 of an engaging piece 33 of the first engaging bracket 31. The first outer end 41 may be engaged with the first engaging portion 34 of the engaging piece 33 in a state where the biasing force and the like are adjusted so that the seat back 3 can always be biased forward regardless of the position of the seat back 3 within its movable range.

[0021] The second biasing spring 50 is a spring body that functions to bias the seat back 3 rearward. Similar to the first biasing spring 40, this second biasing spring 50 has a second outer end (an example of one end of the second biasing spring) 51 located on the outer side in the circumferential direction and curved in a hook shape, a second inner end (an example of the other end of the second biasing spring) 52 located on the inner side in the circumferential direction and curved in a hook shape, and a second winding portion 53 that connects the second outer end 51 and the second inner end 52, and can be configured as a spiral spring. Among these, the second inner end 52 may be hooked at an arbitrary position of the lower arm 20, for example, on the latching bracket 21. Also, the second outer end 51 can be engaged with a second engaging portion 35 of an engaging piece 33 of the first engaging bracket 31 at an arbitrary position of the upper arm 30, for example. However, the second outer end 51 and the second engaging portion 35 engage only while the seat back 3 moves from the forward inclination position to a predetermined position between the forward inclination position and the rearward inclination position. In other words, the second outer end 51 and the second engaging portion 35 do not engage while the seat back 3 moves from the predetermined position to the rearward inclination position. Further, the second biasing spring 50 is arranged in parallel along the first biasing spring 40 on the outer side (left) of the first biasing spring 40 such that the second outer end 51 thereof engages with a second engaging bracket 60 described later.

[0022] When the seat back 3 is biased forward and moved by the action of the first biasing spring 40 from a state where the seat back 3 is in the rearward inclination position, for example, this second biasing spring 50 functions to start biasing the seat back 3 rearward at the timing when the seat back 3 passes through a predetermined position, and to start decelerating its rotational speed (angular velocity). The above-mentioned predetermined position can be said to be a position where, in the movable range of the seat back 3, the region where the seat back 3 is biased by the first and second biasing springs 40, 50 and the region where the seat back 3 is biased only by the first biasing spring 40 are switched. Therefore, hereinafter, this predetermined position will also be referred to as the "second biasing spring operation switching position". As described above, since the biasing force of the second biasing spring 40 is set to be smaller than the biasing force of the first biasing spring 40, the movement of the seat back 3 forward does not stop or switch to movement rearward due to the action of the second biasing spring 50.

[0023] As described above, the second outer end 51 of the second biasing spring 50 does not engage with the engagement piece 33 while the seat back 3 moves from the second biasing spring operating switching position to the reclined position. On the other hand, when a state occurs in which the second outer end 51 of the second biasing spring 50 is not engaged, it may cause the generation of the abnormal noise described above. Therefore, the reclining device 10 of the present disclosure further adopts a configuration including a second engagement bracket (corresponding to the engagement member) 60.

[0024] FIG. 4 is a view showing the mounting structure of the second engagement bracket 60 of the reclining device shown in FIG. 2. FIG. 4(A) is an enlarged perspective view showing only the latching bracket 21 and the second engagement bracket 60 among the reclining devices 10 shown in FIG. 2, and FIG. 4(B) is a cross-sectional view showing a state cut along the line A-A shown in FIG. 4(A). As shown in FIG. 4, the second engagement bracket 60 according to the present embodiment is attached to the latching bracket 21. As shown in FIG. 4, this latching bracket 21 may have a fixing piece 22 fixed to one surface of the lower arm 20 and a latching piece 23 extending upright from one surface of the lower arm 20 in the outer (left) direction (-X direction in FIG. 2) of the seat 1 from the upper end portion of the fixing piece 22. A through hole into which the rotating shaft 4 can be inserted may be formed at a substantially central portion of the fixing piece 22. The latching piece 23 may have a recess formed in at least the side located in front thereof, and this recess functions as a first latching portion 24 for latching the first inner end 42. Further, an insertion hole 26 penetrating the latching piece 23 in the vertical direction may be provided on the upper surface of the latching piece 23, and one side located in front of the inner wall of the insertion hole 26 functions as a second latching portion 25 for latching the second inner end 52. Further, the fixing end 61 of the second engagement bracket 60 described later can be inserted and fixed into the insertion hole 26.

[0025] As described above, in the reclining device 10 according to the present embodiment, both the latching positions of the first and second latching portions 24 and 25 and the fixing position of the fixed end 61 of the second engaging bracket 60 are set on the latching bracket 21. In this way, when the first and second biasing springs 40 and 50 and the fixing portion of the second engaging bracket 60 are aggregated into one member, relative positioning can be easily performed. As a result, during the assembly stage of the reclining device 10 and the like, misalignment is less likely to occur in each of the biasing springs 40 and 50 and the second engaging bracket 60, variations during the manufacture of the reclining device 10 can be suppressed, and the manufacturing yield is improved. Note that the latching positions of the first and second latching portions 24 and 25 and the fixing position of the fixed end 61 of the second engaging bracket 60 described above are not limited to those described above. Therefore, for example, these may be fixed at other positions on the lower arm 20.

[0026] The second engaging bracket 60 engages with the second outer end 51 of the second biasing spring 50 when the seat back 3 moves between the second biasing spring operation switching position and the reclined position. As a specific structure of the second engaging bracket 60, a fixed end 61 that extends in the left-right direction and is fixed to an arbitrary position of the lower arm 20, for example, the latching bracket 21, and a second outer end 51 of the second biasing spring 50 that also extends in the left-right direction and engages with the second outer end 51 of the second biasing spring 50. It can be composed of a metal material including an engaging end 62 disposed at a position corresponding to the second biasing spring operation switching position described above, and a curved portion 63 that connects the fixed end 61 and the engaging end 62.

[0027] The fixed end 61 of the second engagement bracket 60 may be attached to the central positions of the first and second biasing springs 40 and 50 of the lower arm 20, specifically, to the inner positions of the first and second winding portions 43 and 53. Specifically, as shown in FIG. 4, this fixed end 61 may be inserted from above into an insertion hole 26 provided in the latching piece 23 of the latching bracket 21 and fixed. As this fixing method, one or more contact portions between the fixed end 61 and the latching piece 23 may be defined as a joining portion BP, and the joining portion BP can be fixed, for example, by welding. The position and number of the joining portions BP can be arbitrarily changed. For example, as shown in FIG. 4(B), the position can be set at two locations: the position where the tip of the fixed end 61 contacts the latching piece 23 and the position where the tip of the latching piece 23 contacts the fixed end 61.

[0028] One end of the engaging end 62 of the second engagement bracket 60, more specifically, the end face located in front of the engaging end 62, is aligned with an engaging position EP (see FIG. 5(A) etc.) corresponding to the above-described second biasing spring actuation switching position, so that it may be engageable with the second outer end 51 of the second biasing spring 50. Specifically, the engaging end 62 extending in the left-right direction has its vertical position set between the first and second winding portions 43 and 53 and the engaging piece 33 of the first engagement bracket 31, and the end position on the side (the +X direction in FIG. 2) not connected to the curved portion 63 in the left-right direction is set between the left-right position of the second outer end 51 and the left-right position of the first outer end 41. Thereby, the engaging end 62 contacts and engages only with the second outer end 41 and does not contact other members regardless of the position of the seat back 3. In the present embodiment, the vertical position of the engaging end 62 is set between the first and second winding portions 43 and 53 and the engaging piece 33 of the first engagement bracket 31 as an example, but the present disclosure is not limited thereto. For example, the vertical positions of the engaging end 62 and the engaging piece 33 may be set conversely.

[0029] The curved portion 63 of the second engagement bracket 60 may connect the fixed end 61 and the engagement end 62. Specifically, it may be curved so as to bypass the first and second winding portions 43 and 53 located between the fixed end 61 and the engagement end 62. The second engagement bracket 60 including this curved portion 63 may have a substantially U-shaped form along the first and second winding portions 43 and 53 when viewed from the front-rear direction. By forming the second engagement bracket 60 in this way, the occupied area of the second engagement bracket 60 is suppressed to be small.

[0030] Since the engagement end 62 of the second engagement bracket 60 is positioned in accordance with the above-described second biasing spring operation switching position, as a result, by adjusting the layout of the engagement end 62 of the second engagement bracket 60, the second biasing spring operation switching position can be determined. Here, in the above-described embodiment, as shown in FIGS. 1 to 4, as the second engagement bracket 60, an example including an engagement end 62 extending in the horizontal direction is illustrated. However, the shape of the second engagement bracket applicable to the reclining device of the present disclosure is not limited to this.

[0031] FIG. 5 is an explanatory diagram for explaining a modified example of the second engagement bracket. FIG. 5(A) is a side view of one side of the reclining device shown in FIG. 2, FIG. 5(B) is a side view of one side showing a modified example in which the second engagement bracket of the reclining device shown in FIG. 5(A) is changed, and FIG. 5(C) is a side view of one side showing another modified example in which the second engagement bracket of the reclining device shown in FIG. 5(A) is changed. FIGS. 5(A) to 5(C) each show a side view of the state in which the seat back 3 is in the above-described second biasing spring operation switching position. As shown in FIG. 5(A), in the above-described second engagement bracket 60, the curved portion 63 extends along the vertical direction. On the other hand, in the second engagement bracket 60A as a modified example, its curved portion 63A is further curved so as to be inclined rearward compared to the curved portion 63, and in the second engagement bracket 60B as another modified example, its curved portion 63B is further curved so as to be inclined forward compared to the curved portion 63.

[0032] In relation to the fact that the curved portions 63A and 63B of the respective modified examples are inclined rearward or forward, the engaging ends 62A and 62B of the second engaging brackets 60A and 60B shown in the respective modified examples are inclined by a specific angle with respect to the horizontal line HL. Specifically, the engaging end 62A of the second engaging bracket 60A according to one modified example is inclined by a first angle θ1 (for example, -10°) in the clockwise direction when viewed from the outside in the sheet width direction with respect to the horizontal line HL, and the engaging end 62B of the second engaging bracket 60B according to another modified example is inclined by a second angle θ2 (for example, 10°) in the counterclockwise direction when viewed from the outside in the sheet width direction with respect to the horizontal line HL. Further, in relation to the fact that the curved portions 63A and 63B of the respective modified examples are inclined rearward or forward, the positions (engaging positions) where the respective engaging ends 62, 62A, and 62B engage with the second outer end 51 are also different from each other. Specifically, the engaging position EP1 defined by the second engaging bracket 60A according to one modified example is located rearward of the engaging position EP defined by the second engaging bracket 60, and the engaging position EP2 defined by the second engaging bracket 60B according to another modified example is located forward of the engaging position EP defined by the second engaging bracket 60. Since the respective engaging positions EP, EP1, and EP2 define the second biasing spring actuation switching position, the reclining device 10 according to the present embodiment can relatively easily adjust the second biasing spring actuation switching position, that is, the biasing timing of the second biasing spring 50, by selectively using the second engaging brackets having different shapes as described above.

[0033] FIG. 6 is a diagram showing the relationship between the operating position of the seat back and torque and angular velocity. FIG. 7 is a diagram showing the operating state of the reclining device shown in FIG. 2. Below, with reference to FIGS. 6 and 7, an example of the state of the reclining device 10 when the seat back 3 moves from the reclined position to the forward inclined position, and the transition of the change in torque and angular velocity (return speed to the forward inclined position) at that time will be described. Note that in the graph shown in FIG. 6, an example of the transition of the torque value (N·m) and angular velocity (deg / s) when the horizontal axis is the tilt angle of the seat back 3 is shown by a solid line. Also, in the seat back tilt angle - torque value graph shown in the middle of FIG. 6, what is shown by a dashed line represents the self-weight moment of the seat back 3, and it is a moment in the opposite direction to the first biasing spring 40. The value of this self-weight moment of the seat back 3 corresponds to the minimum value of the torque value required for the seat back 3 to move forward. In other words, when the torque value acting on the seat back 3 becomes smaller than the value of this self-weight moment of the seat back 3, it indicates a value at which the reclining device 10 cannot move the seat back 3 forward. Further, in the upper part of FIG. 6, the operating ranges of the respective biasing springs 40 and 50 with respect to the tilt angle of the seat back 3 are shown.

[0034] When the locking state of the seat back 3 is released by the operation of the recliner 5 in the state where the seat back 3 is in the reclined position (see FIG. 7(A)), the seat back 3 starts to move forward by the biasing force of the first biasing spring 40. Here, when the seat back 3 is in the reclined position, the second outer end 51 of the second biasing spring 50 is engaged with the engaging end 62 of the second engaging bracket 60 as shown in FIG. 7(A). That is, the biasing force of the second biasing spring 50 does not act on the seat back 3, and in addition, since the second outer end 51 is engaged with the engaging end 62, the generation of abnormal noise is suppressed. On the other hand, when the seat back 3 is in the reclined position, the first biasing spring 40 is in the most contracted state, so the torque value acting on the seat back 3 at this time is the maximum in the entire movable range.

[0035] When the movement of the seat back 3 starts, the seat back 3 rotates forward while increasing its angular velocity. The torque value acting on the seat back 3 at this time gradually decreases due to the decrease in the biasing force accompanying the elongation of the first biasing spring 40. When the seat back 3 reaches the second biasing spring activation switching position, as shown in FIG. 7(B), the second engaging portion 35 of the engaging piece 33 reaches the engaging position EP and engages with the second outer end 51 of the second biasing spring 50, so that the biasing force of the second biasing spring 50 is transmitted to the seat back 3. In other words, when the seat back 3 reaches the second biasing spring activation switching position, the object that the second outer end 51 of the second biasing spring 50 engages with switches from the engaging end 62 to the engaging piece 33, and the biasing of the seat back 3 by the second biasing spring 50 is started.

[0036] The seat back 3 that has passed the second biasing spring activation switching position continues to rotate forward while increasing its angular velocity by the biasing force of the first biasing spring 40, passes through the standard position (see FIG. 7(C)) corresponding to the position of the seat back 3 when the occupant normally uses it, and moves to the forward tilt position (see FIG. 7(D)) and stops. The angular velocity continues to increase from the rear tilt position to the forward tilt position, but the degree of increase in the angular velocity after passing the second biasing spring activation switching position gradually increases compared to the degree of increase in the angular velocity (shown by the dotted line in FIG. 6) when the biasing force of the second biasing spring 50 is not added because the biasing force of the second biasing spring 50 is added. Similarly, the torque value acting on the seat back 3 that has passed the second biasing spring activation switching position continues to decrease as the biasing force of the first biasing spring 40 decreases, but the degree of decrease is steeper compared to the degree of decrease in the torque value (shown by the dotted line in FIG. 6) when the biasing force of the second biasing spring 50 is not added because the biasing force of the second biasing spring 50 acts in the opposite direction to the biasing force of the first biasing spring 40.

[0037] As described above, according to the reclining device 10 according to the present embodiment, by adopting the second biasing spring 50, it is possible to control the angular velocity of the seat back 3 moving between the preset second biasing spring operating switching position and the forward tilting position and the torque acting on the seat back 3. Therefore, while smoothly realizing the movement of the seat back 3, it is possible to avoid or suppress the seat back 3 from colliding with a seated person sitting on the seat cushion 2 or luggage placed on the seat cushion 2 with a strong force.

[0038] Also, during the operation of the reclining device 10 according to the present embodiment, the second outer end 51 of the second biasing spring 50 is always engaged with either the engaging piece 33 connected to the upper arm 30 or the engaging end 62 connected to the lower arm 20, and the generation of abnormal noise due to the state where the second outer end 51 is not engaged is suppressed. Furthermore, since the second biasing spring operating switching position (i.e., the engagement position EP between the second outer end 51 and the engaging end 62) is uniquely determined by the second engaging bracket 60, in order to specify the second biasing spring operating switching position, it is almost unnecessary to finely adjust the latching position of the second latching portion 25 in consideration of the natural length of the second biasing spring 50 or to adjust the natural length of the second biasing spring 50. Also, after latching the second biasing spring 50, the second biasing spring operating switching position does not shift due to, for example, the elongation or contraction of the second biasing spring 50 or the variation in the position of the second outer end 51 of the second biasing spring 50. Therefore, it is possible to accurately control the torque and angular velocity during the movement of the seat back 3.

[0039] In addition, the reclining device 10 according to the present embodiment can easily control the angular velocity of the seat back 3 and the torque acting on the seat back 3 by adjusting the timing at which the second biasing spring 50 biases the seat back 3. As a result, when the mass of the seat back changes due to the attachment of equipment (side airbag, headrest with angle adjustment, lumbar support, single - port speaker, back board, back tray, armrest, heater, etc.) to the seat back 3, or when unexpected acceleration or deceleration occurs in the moving speed of the seat back 3 due to the influence of friction caused by rubbing between the skins (fabric, genuine leather, etc.), the moving speed can be adjusted to a desired value relatively easily.

[0040] The present disclosure is not limited to the above - described embodiments, and various modifications can be made and implemented without departing from the gist of the present disclosure. And all of them are included in the technical idea of the present disclosure.

Explanation of Reference Numerals

[0041] 1 Seat 2 Seat Cushion 3 Seat Back 4 Rotation Axis 10 Reclining Device 20 Lower Arm (an example of the first arm) 21 Latching Bracket (an example of the attachment member) 30 Upper Arm (an example of the second arm) 31 First Engagement Bracket 40 First Biasing Spring (an example of the first biasing member) 41 First Outer End (an example of one end of the first biasing member) 42 First Inner End (an example of the other end of the first biasing member) 50 Second Biasing Spring (an example of the second biasing member) 51 Second Outer End (an example of one end of the second biasing member) 52 Second Inner End (an example of the other end of the second biasing member) 60, 60A, 60B Second Engagement Bracket (an example of the engagement member) 61 Fixed End 62, 62A, and 62B are mating ends 63, 63A, and 63B are curved portions EP, EP1, and EP2 are mating positions

Claims

1. a first arm attached to the seat cushion; a second arm attached to the seat back and rotatably supported with respect to the first arm; a first biasing member whose one end engages with the second arm while the seat back moves between a reclined position in which the seat back is reclined with respect to the seat cushion and a forward-tilted position in which the seat back is tilted forward with respect to the seat cushion in order to bias the seat back forward; a second biasing member whose one end engages with the second arm while the seat back moves between the forward-tilted position and a predetermined position between the forward-tilted position and the reclined position, in order to bias the seat back rearward with a biasing force smaller than the biasing force of the first biasing member while the seat back moves between the forward-tilted position and the predetermined position; an engaging member that engages with the one end of the second biasing member while the seat back moves between the predetermined position and the reclined position; the other end of the second biasing member and one end of the engaging member are attached to an attachment member fixed to the first arm; a reclining device.

2. the other end of the first biasing member is attached to the attachment member; the reclining device according to claim 1.

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