Seat adjustment device for a vehicle

Abstract

A seat adjusting apparatus for a vehicle includes a fixed bracket having a rear portion to which a backrest frame is rotatably coupled, and a seat cushion frame disposed on an upper side of the fixed bracket and tilted by a link mechanism. In particular, the link mechanism includes a first link member hinged to a front portion of the fixed bracket and supporting a front portion of the seat cushion frame, and connected to a driving unit to raise and lower the front portion of the seat cushion frame by the driving unit, a second link member hinged to the rear portion of the fixed bracket and the seat cushion frame to guide a rear portion of the seat cushion frame, and a third link member hinged to the fixed bracket and the seat cushion frame to determine a tilt position of the seat cushion frame when the seat cushion frame is raised.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a seat adjusting device for a vehicle, which can stabilize the posture of an occupant. BACKGROUND

[0002] The statements in the background technical field are provided only to assist understanding of the present disclosure and should not be construed as admitting that the present disclosure falls into the prior art.

[0003] Generally, in a vehicle, a front seat on which a driver and an assistant sit is provided, and a rear seat for other occupants is provided behind the front seat, and various convenience devices for improving the convenience of the occupants are installed on the seats.

[0004] For example, the convenience devices installed on the seats include a seat position adjusting device that adjusts the position of the seat by moving the seat in the front-rear direction by the manipulation of the occupant, a reclining device that adjusts the inclination of the seat back, a height device that adjusts the height of the seat, or a tilting device that adjusts the tilting angle of the seat.

[0005] Recently, as autonomous vehicles are developed, the adjustment of the seat position is more widely applied. However, we found that the seat using the tilting device in the related art is tilted as a whole, and thus the lower body and the hips of the occupant are raised together. Therefore, in the seat tilting mode, the sitting height of the occupant is changed, which can cause a problem that the sitting posture of the occupant becomes uncomfortable.

[0006] The description in the background art is only intended to help understanding of the background of the present disclosure and is not intended to mean that the present disclosure falls within the scope of the prior art known to those skilled in the art. SUMMARY

[0007] The present disclosure provides a seat adjusting device for a vehicle configured such that, when a seat cushion is tilted, the front of the seat cushion is raised and the rear of the seat cushion is lowered, and thus the lower body of the occupant is not raised as a whole, so that the feet of the occupant are not excessively raised. Thereby, the present disclosure does not need a separate footrest for supporting the feet of the occupant, and can improve the convenience by achieving the stable posture of the occupant.

[0008] In one form of the present disclosure, a seat adjusting apparatus for a vehicle can include a fixed bracket having a rear portion to which a backrest frame is rotatably connected, and a seat cushion frame disposed on an upper side of the fixed bracket and tilted by a link mechanism. In particular, the link mechanism includes a first link member hinged to a front portion of the fixed bracket and supporting a front portion of the seat cushion frame, and connected to a driving unit to raise and lower the front portion of the seat cushion frame according to whether the driving unit is operated, a second link member hinged to a rear portion of the fixed bracket and to a middle portion or a rear portion of the seat cushion frame to guide movement of the rear portion of the seat cushion frame, and a third link member hinged to the fixed bracket and the seat cushion frame between the first link member and the second link member to determine a tilt position of the seat cushion frame when the seat cushion frame is raised. In one form, the first link member, the second link member, and the third link member are disposed to be spaced apart from each other along a length direction of the fixed bracket.

[0009] The first link member can include at least one guide link combined with the front portion of the seat cushion frame and including a first portion extending downward from the front portion of the seat cushion frame and a second portion formed with a guide groove, and a rotation link having a first end hinged to the front portion of the fixed bracket and a second end inserted into the guide groove of the at least one guide link.

[0010] In one form, the second portion of the at least one guide link can extend obliquely rearward from the first portion of the at least one guide link, and the guide groove can extend in the same direction as an extension direction of the second portion of the at least one guide link. In another form, the rotation link can be installed to rotate from front to rear when the seat cushion frame is raised.

[0011] In other forms, the at least one guide link includes a pair of guide links disposed on first and second sides of the fixed bracket.

[0012] The first link member can further include a connection link passing through the guide grooves of the pair of guide links disposed on the two sides of the fixed bracket and hinged to the second end of the rotation link.

[0013] The driving unit can include a driving motor installed at the front portion of the seat cushion frame, and a power transmission portion connected to the driving motor and having a length varied in a linear direction according to whether the driving motor is operated, and hinged to the connection link and moving the rotation link along the guide groove together with the connection link by moving the connection link when the driving motor is operated.

[0014] One end of the second link member is hinged to a position higher than positions of the first link member and the third link member at the rear portion of the fixed bracket, and the other end can be hinged to the middle portion or the rear portion of the seat cushion frame and extend downwardly bent.

[0015] The hinge bracket hinged to the other end of the second link member can be provided at the middle portion or the rear portion of the seat cushion frame, and the hinge bracket can be formed to be inclined downward.

[0016] The third link member can extend forwardly inclined from the fixed bracket and can be connected to the seat cushion frame, and can be formed to be in an inclined state with respect to the front portion even in the case where the seat cushion frame is raised.

[0017] The third link member can be located at the central portion of the seat cushion frame and can be hinged to the fixed bracket and the seat cushion frame, and when the seat cushion frame is raised, the front portion of the seat cushion frame is raised and the rear portion of the seat cushion frame is lowered, so that the leg portion of the occupant is lifted and the hip point of the occupant is moved downward.

[0018] The third link member can be located at the rear portion side of the seat cushion frame and can be hinged to the fixed bracket and the seat cushion frame, and when the seat cushion frame is raised, the front portion of the seat cushion frame is inclined at a greater angle than the rear portion, so that the leg portion of the occupant is lifted but the hip point of the occupant is maintained.

[0019] The third link member can be located at the front portion side of the seat cushion frame and can be hinged to the fixed bracket and the seat cushion frame, and when the seat cushion frame is raised, the rear portion of the seat cushion frame is inclined at a greater angle than the front portion, so that the hip point of the occupant is moved lower downward than the height at which the leg portion of the occupant is lifted.

[0020] According to the seat adjusting apparatus for a vehicle having the above-described structure, when the seat cushion is inclined, the front portion of the seat cushion is raised and the rear portion of the seat cushion is lowered, so that the lower body of the occupant is not raised as a whole, thereby preventing the feet of the occupant from being excessively lifted. Thus, a separate footrest for supporting the feet of the occupant is not required, and convenience is improved by achieving a stable posture of the occupant.

[0021] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0022] So that the disclosure will be understood in a thorough and complete context, various forms of the present disclosure will now be described, by way of example, and in conjunction with the drawings in which:

[0023] Figure 1 is a view showing a seat adjusting apparatus for a vehicle according to one form of the present disclosure;

[0024] Figure 2 is a view showing Figure 1 the seat adjusting apparatus for a vehicle shown in the state before operation;

[0025] Figure 3 is a view showingFigure 1 a view of the seat adjusting device for a vehicle shown in a state after operation;

[0026] Figure 4 is a view showing Figure 1 a view of the driving unit and the first link member of the seat adjusting device for a vehicle shown;

[0027] Figure 5 is a view showing Figure 1 a view of the second link member of the seat adjusting device for a vehicle shown;

[0028] Figure 6 is a view showing Figure 1 a view of the third link member of the seat adjusting device for a vehicle shown;

[0029] Figure 7 is a view showing a state before and after operation in a case where the third link member is located at a reference position;

[0030] Figure 8 is a view showing a state before and after operation in a case where the third link member is disposed at a rear portion of the reference position; and

[0031] Figure 9 is a view showing a state before and after operation in a case where the third link member is disposed at a front portion of the reference position.

[0032] The accompanying drawings described herein are for purposes of illustration only and are not intended to limit the scope of the present disclosure in any way. DETAILED DESCRIPTION

[0033] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, the same reference numerals are used for similar or corresponding parts and features.

[0034] Hereinafter, a seat adjusting device for a vehicle according to an exemplary form of the present disclosure will be described with reference to the accompanying drawings.

[0035] Figure 1 is a view showing a seat adjusting device for a vehicle according to an exemplary form of the present disclosure, Figure 2 is a view showing Figure 1 a view of the seat adjusting device for a vehicle shown in a state before operation, Figure 3 is a view showing Figure 1 a view of the seat adjusting device for a vehicle shown in a state after operation, Figure 4 is a view showing Figure 1 a view of the driving unit and the first link member of the seat adjusting device for a vehicle shown, Figure 5 is a view showing Figure 1A view of a second link member of a seat adjusting apparatus for a vehicle, Figure 6 is a view of a third link member of a seat adjusting apparatus for a vehicle, Figure 1 is a view of a third link member of a seat adjusting apparatus for a vehicle, Figure 7 is a view illustrating a state before and after operation when the third link member is located at a reference position, Figure 8 is a view illustrating a state before and after operation when the third link member is located at a rear portion of the reference position, and Figure 9 is a view illustrating a state before and after operation when the third link member is located at a front portion of the reference position.

[0036] As Figures 1 to 3 illustrated, a seat adjusting apparatus for a vehicle includes a fixed bracket 100 having a rear portion 100b to which a back frame 500 is rotatably connected, and a seat cushion frame 200 disposed at an upper side of the fixed bracket 100 and configured to be inclined by a plurality of link mechanisms 300 disposed to be spaced apart from each other along a length direction of the fixed bracket 100.

[0037] Here, the fixed bracket 100 is mounted on a moving rail R2 that is slidable on a fixed rail Rl and moves along the fixed rail Rl together with the moving rail R2. The fixed bracket 100 can be provided with a base bracket 110 in consideration of a mounting position of the back frame 500, and the back frame 500 can be rotatably mounted on the base bracket 110 by a recliner.

[0038] The fixed bracket 100 is provided with the plurality of link mechanisms 300, and the seat cushion is inclinably mounted by the plurality of link mechanisms 300. Here, the link mechanisms 300 can include a first link member 310 hinged to a front portion 100a of the fixed bracket 100 and supporting a front portion 200a of the seat cushion frame 200, and connected to a driving unit 400 to raise and lower the front portion 200a of the seat cushion frame 200 according to an operation of the driving unit 400, a second link member 320 hinged to a rear portion 100b of the fixed bracket 100 and hinged to a middle portion 200c or a rear portion 200b of the seat cushion frame 200 to guide a movement of the rear portion 200b of the seat cushion frame 200, and a third link member 330 hinged to the fixed bracket 100 and the seat cushion frame 200 and disposed between the first link member 310 and the second link member 320. In detail, the third link member 330 is configured to determine an inclined position of the seat cushion frame 200 when the seat cushion frame 200 is raised.

[0039] That is, since the first link member 310 is hinged to the front portion 100a of the fixed bracket 100 and supports the seat cushion frame 200, the fixed bracket 100 can be raised or lowered as the first link member 310 rotates. The first link member 310 can be rotated by the driving unit 400 installed on the seat cushion frame 200 or the fixed bracket 100.

[0040] The second link member 320 is hinged to the rear portion 100b of the fixed bracket 100 and the middle portion 200c or the rear portion 200b of the seat cushion frame 200. Thereby, when the driving unit 400 operates and the front portion 200a of the seat cushion frame 200 is raised by the first link member 310, the rear portion 200b of the seat cushion frame 200 is rotationally moved in correspondence to the raising of the front portion 200a, and thus the reclining operation of the seat cushion frame 200 can be performed.

[0041] The third link member 330 is hinged to the fixed bracket 100 and the seat cushion frame 200 and disposed between the first link member 310 and the second link member 320 to determine the reclining position of the seat cushion frame 200 when the seat cushion frame 200 is raised. That is, when the seat cushion frame 200 is raised, the third link member 330 rotates with the seat cushion frame 200 to recline the seat cushion frame 200. As described above, since the third link member 330 rotates with the seat cushion frame 200 when the seat cushion frame 200 is raised, the front portion 200a of the seat cushion frame 200 is raised, but the rear portion 200b of the seat cushion frame 200 is lowered due to the third link member 330 adjusting the raising of the front portion 200a.

[0042] As described above, when the driving unit 400 operates, the seat cushion frame 200 performs the reclining operation in which the front portion 200a of the seat cushion frame 200 is raised and the rear portion 200b is lowered by the first link member 310, the second link member 320, and the third link member 330, so that the occupant as a whole is not raised, but only the front portion of the legs of the occupant is raised, thereby maintaining a comfortable sitting posture.

[0043] The present disclosure as described above will be described in detail. It can be seen from Figures 2 to 4 that the first link member 310 can include a guide link 311 combined with the front portion 200a of the seat cushion frame 200 and extending downward, and having a guide groove 312 formed on the guide link 311, and a rotation link 313 hinged to the front portion 100a of the fixed bracket 100 at one end and inserted into the guide groove 312 of the guide link 311 at the other end.

[0044] As described above, since the first link member 310 includes the guide link 311 and the rotation link 313, and the rotation link 313 moves along the guide groove 312 of the guide link 311 as the rotation link 313 rotates, the guide link 311 linearly moves by the rotational movement of the rotation link 313 to raise or lower the seat cushion frame 200.

[0045] To this end, the guide link 311 can include a first portion extending downward from the front portion 200a of the seat cushion frame 200 and a second portion formed with a guide groove. In one form, as shown, the second portion of the guide link 311 extends obliquely rearward from the first portion of the guide link 311, and the guide groove 312 can extend in the same direction as the extension direction of the second portion of the guide link 311. Further, the rotation link 313 can be installed to rotate from front to rear as the seat cushion frame 200 rises. Thus, when the driving unit 400 operates, the rotation link 313 rotates from front to rear while the guide link 311 is raised by the rotation link 313 moved along the guide groove 312, thereby causing the seat cushion frame 200 to rise. Here, the rotation direction of the rotation link 313 and the extension direction of the guide link 311 can be configured to be opposite to each other as the seat cushion frame 200 rises, but when the rotation direction of the rotation link 313 and the extension direction of the guide link 311 are configured to be opposite to each other, each link is exposed to the front of the seat cushion frame 200, so the rotation link 313 is formed to rotate from front to rear, and the guide link 311 is formed to extend rearward. Figure 4

[0046] On the other hand, the first link member 310 can further include a connection link 314 configured to pass through the guide groove 312 of each guide link 311 provided on both sides of the fixed bracket 100 and be hinged to the other end of each rotation link 313. By this, the first link member 310 provided on both sides of the fixed bracket 100 can be simultaneously rotated by connection with the connection link 314. In the present disclosure, not only the first link member 310 but also the second link member 320 and the third link member 330 are also provided in pairs on both sides of the fixed bracket 100.

[0047] The driving unit 400 that rotates the first link member 310 includes a driving motor 410 installed at the front portion 200a of the seat cushion frame 200, and a power transmission portion 420 connected to the driving motor 410 and having a length that changes in a straight line direction according to whether the driving motor 410 is operated, and being hinged to the connection link 314, thereby moving the rotation link 313 along the guide groove 312 together with the connection link 314 by moving the connection link 314 rearward when the driving motor 410 is operated.

[0048] Here, the driving motor 410 can be configured of a motor that can be reversed, and can be installed on the seat cushion frame 200 by a motor bracket 411. The power transmission portion 420 can be configured of a load screw that receives a rotational force from the driving motor 410 to be pulled out or pulled in. Further, the power transmission portion 420 can be hinged to the connection link 314 through a connection bracket 315, and can be pulled out rearward when the driving motor 410 is operated.​

[0049] Thus, when the driving motor 410 operates to raise the seat cushion frame 200, the power transmission part 420 is pulled out as the driving motor 410 operates to push the connection link 314 backward, and the rotation link 313 connected to the connection link 314 rotates backward while moving along the guide groove 312 of the guide link 311, so that the guide link 311 is lifted by the rotation link 313, raising the seat cushion frame 200. As described above, the guide link 311 and the rotation link 313 provided on both sides of the fixed bracket 100 are simultaneously rotated by moving the connection link 314 by one driving unit 400, so that the seat cushion frame 200 can be stably raised.

[0050] On the other hand, as Figure 5 shown, one end of the second link member 320 is hinged to a position higher than those of the first link member 310 and the third link member 330 at the rear of the fixed bracket 100, and the other end is hinged to the middle part 200c or the rear part 200b of the seat cushion frame 200 and extends downwardly bent.

[0051] That is, the second link member 320 can be formed in a curved "C" shape, and one end can be hinged to the base bracket 110 provided on the fixed bracket 100, and the other end can be hinged to the middle part 200c or the rear part 200b of the seat cushion frame 200, so that it can be inclined according to the raising and lowering of the seat cushion frame 200. The above-described second link member 320 has a rotation point provided at the middle part 200c or the rear part 200b of the seat cushion frame 200, so that the rear part 200b of the seat cushion frame 200 is lowered while the front part 200a is raised. If the second link member 320 is simply formed in a straight line, when the front part 200a of the seat cushion frame 200 is raised, the second link member 320 is rotated upwardly together so that the seat cushion frame 200 is raised forwardly. However, since the second link member 320 of the present disclosure is formed in a curved "C" shape, when the seat cushion frame 200 is raised, the seat cushion frame 200 can be moved backwardly, so that the raising operation of the front part 200a and the lowering operation of the rear part 200b of the seat cushion frame 200 can be simultaneously performed.

[0052] Here, the hinge bracket 120 hinged to the other end of the second link member 320 can be provided at the middle part 200c or the rear part 200b of the seat cushion frame 200, and the hinge bracket 120 can be formed downwardly inclined. Thus, the curved second link member 320 is connected in a straight line by the hinge bracket 120, so that the second link member 320 can stably support the inclination due to the raising of the front part 200a and the lowering of the rear part 200b of the seat cushion frame 200 when the seat cushion frame 200 is raised, by the hinge bracket 120.

[0053] In addition, as Figure 6As shown, in a case where the seat cushion frame 200 is separately configured at the front portion 200a and the rear portion 200b, the hinge bracket 120 can form a structure connecting the front portion 200a and the rear portion 200b of the seat cushion frame 200.

[0054] On the other hand, the third link member 330 can extend obliquely forward from the fixed bracket 100 and can be connected to the seat cushion frame 200, and can be formed to be in an oblique state with respect to the front portion even in a case where the seat cushion frame 200 is raised. Since the third link member 330 extends obliquely forward from the fixed bracket 100, when the seat cushion frame 200 is raised, the third link member 330 guides the rearward movement of the seat cushion frame 200 while corresponding to the raising of the front portion 200a of the seat cushion frame 200. To this end, the third link member 330 can be formed to be shorter than the final length of the first link member 310 unfolded.

[0055] The inclination angle of the seat cushion frame 200 can be adjusted according to the installation position of the third link member 330 between the first link member 310 and the second link member 320.

[0056] That is, as shown, since the third link member 330 is positioned at the central portion of the seat cushion frame 200 and is hinged with the fixed bracket 100 and the seat cushion frame 200, when the seat cushion frame 200 is raised, the front portion 200a of the seat cushion frame 200 is raised and the rear portion 200b is lowered, so that the leg portion of the occupant is lifted and the hip point of the occupant is moved downward. Figure 7

[0057] Here, since the third link member 330 is installed on the central side between the first link member 310 connected to the front portion 200a of the seat cushion frame 200 and the second link member 320 connected to the middle portion 200c or the rear portion 200b of the seat cushion frame 200, when the seat cushion frame 200 is raised, the front portion 200a of the seat cushion frame 200 can be raised and the rear portion 200b of the seat cushion frame 200 can be lowered. That is, as shown, since the third link member 330 adjusts the rotational position of the seat cushion frame 200 when the seat cushion frame 200 is raised, the front portion 200a of the seat cushion frame 200 is raised by about 31 mm, and the rear portion 200b of the seat cushion frame 200 is lowered by about 23 mm. Figure 7

[0058] By this, the leg portion of the occupant is lifted and moved upward, while the hip point of the occupant is moved downward.

[0059] On the other hand, as shown, Figure 8 ​​As shown, since the third link member 330 is positioned on the rear 200b side of the seat cushion frame 200 and is hinged to the fixed bracket 100 and the seat cushion frame 200, when the seat cushion frame 200 is raised, the front 200a of the seat cushion frame 200 is tilted at a larger angle than the rear 200b, and thus the leg portion of the occupant is raised, but the hip point of the occupant is maintained.

[0060] That is, in a case where the third link member 330 is installed in the rear 200b of the seat cushion frame 200 near a position where the second link member 320 is connected to the seat cushion frame 200, when the seat cushion frame 200 is raised, the front 200a of the seat cushion frame 200 is raised, but the rear 200b has a relatively small lowering distance. Thus, as shown, Figure 8 As shown, since the third link member 330 is positioned on the front 200a side of the seat cushion frame 200 and is hinged to the fixed bracket 100 and the seat cushion frame 200, when the seat cushion frame 200 is raised, the rear 200b of the seat cushion frame 200 is tilted at a larger angle than the front 200a, and thus the hip point of the occupant can be moved downwardly lower than the height to which the leg portion of the occupant is raised.

[0061] Thus, the leg portion of the occupant is raised, but the height of the hip point of the occupant does not change greatly, and thus the position of the hip point can be maintained.

[0062] On the other hand, as shown, Figure 9 As shown, since the third link member 330 is positioned on the front 200a side of the seat cushion frame 200 and is hinged to the fixed bracket 100 and the seat cushion frame 200, when the seat cushion frame 200 is raised, the rear 200b of the seat cushion frame 200 is tilted at a larger angle than the front 200a, and thus the hip point of the occupant can be moved downwardly lower than the height to which the leg portion of the occupant is raised.

[0063] That is, in a case where the third link member 330 is installed in the front 200a of the seat cushion frame 200 near a position where the first link member 310 is connected to the seat cushion frame 200, when the seat cushion frame 200 is raised, the front 200a of the seat cushion frame 200 has a relatively small raising distance, but a large lowering distance of the rear 200b can be ensured.

[0064] Thus, as shown, Figure 9 As shown, since the third link member 330 adjusts the rotational position of the seat cushion frame 200 when the seat cushion frame 200 is raised, the front 200a of the seat cushion frame 200 is raised by about 17 mm, and the rear 200b of the seat cushion frame 200 is lowered by about 24 mm.

[0065] Thus, the hip point of the occupant can be moved downwardly lower than the height to which the leg portion of the occupant is raised.

[0066] As described above, when the seat cushion frame 200 is raised, the third link member 330 causes the front portion 200a of the seat cushion frame 200 to be raised and the rear portion 200b of the seat cushion frame 200 to be lowered, and by changing the inclination trajectory of the seat cushion frame 200 through the mounting position of the third link member 330, an optimal posture matching a desired seat sitting posture of the occupant can be achieved.

[0067] According to the present disclosure as described above, the seat cushion frame 200 is initially positioned as shown in Figure 2 . Here, as shown in Figure 3 , when the driving unit 400 is operated at the time of the inclination operation of the seat cushion frame 200, the front portion 200a of the seat cushion frame 200 is raised by the unfolding operation of the guide link 311 and the rotation link 313 of the first link member 310. In this case, the third link member 330 also rotates together with the seat cushion frame 200 and guides the inclination of the seat cushion frame 200, and due to the rotation of the second link member 320, the front portion 200a of the seat cushion frame 200 is raised while the rear portion 200b of the seat cushion frame 200 is lowered.

[0068] Thereby, in the inclination mode of the seat, the hips of the occupant are not lifted, so that the lower body of the occupant can maintain a stable posture.

[0069] According to the seat adjusting apparatus for a vehicle having the above-described structure, when the seat cushion is inclined, the front portion of the seat cushion is raised while the rear portion of the seat cushion is lowered, so that the lower body of the occupant is not entirely raised, thereby preventing the feet of the occupant from being excessively lifted. Thereby, a separate footrest for supporting the feet of the occupant is not required, and convenience is improved by achieving a stable posture of the occupant.

[0070] While the exemplary forms of the present disclosure have been illustrated and described for the purposes of facilitating the understanding of this disclosure, it will be apparent to those skilled in the art that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the present disclosure.

Claims

1.A seat adjusting apparatus for a vehicle, comprising: a fixed bracket having a rear portion to which a back frame is rotatably coupled; and a seat cushion frame disposed on an upper side of the fixed bracket and inclined by a link mechanism, wherein the link mechanism includes: a first link member hinged to a front portion of the fixed bracket and supporting a front portion of the seat cushion frame, and coupled to a driving unit to raise and lower the front portion of the seat cushion frame according to an operation of the driving unit; a second link member hinged to a rear portion of the fixed bracket and to a middle portion or a rear portion of the seat cushion frame to guide a movement of the rear portion of the seat cushion frame; and a third link member hinged to the fixed bracket and the seat cushion frame and disposed between the first link member and the second link member to determine an inclined position of the seat cushion frame when the seat cushion frame is raised, wherein the first link member, the second link member, and the third link member are disposed to be spaced apart from each other along a length direction of the fixed bracket, the fixed bracket is provided with a base bracket, a first end of the second link member is hinged to a portion of the base bracket higher than positions of the first link member and the third link member at the rear portion of the fixed bracket, and a second end is hinged to the middle portion or the rear portion of the seat cushion frame and extends downwardly and bent. 2.The seat adjusting apparatus of claim 1, wherein: the first link member includes: at least one guide link combined with the front portion of the seat cushion frame and including a first portion extending downwardly from the front portion of the seat cushion frame and a second portion formed with a guide groove; and a rotation link including: a first end hinged to the front portion of the fixed bracket, and a second end inserted into the guide groove of the at least one guide link. 3.The seat adjusting apparatus of claim 2, wherein: the second portion of the at least one guide link extends obliquely backwardly from the first portion of the at least one guide link, the guide groove extends in the same direction as an extending direction of the second portion of the at least one guide link, and the rotation link rotates when the seat cushion frame is raised. 4.The seat adjusting apparatus of claim 3, wherein: the at least one guide link includes a pair of guide links disposed on first and second sides of the fixed bracket. 5.The seat adjusting apparatus of claim 4, wherein: the first link member further includes a connection link passing through the guide grooves of the pair of guide links and hinged to the second end of the rotation link. 6.The seat adjusting apparatus of claim 5, wherein: the driving unit includes: a driving motor mounted at the front portion of the seat cushion frame; and a power transmission portion coupled to the driving motor and having a length varied in a straight line direction according to an operation of the driving motor, wherein the power transmission portion is configured to: be hinged to the connection link, and move the rotation link along the guide groove together with the connection link by moving the connection link when the driving motor is operated. 7.The seat adjusting apparatus according to claim 1, wherein a hinge bracket that is hinged to a second end of the second link member is provided at a middle portion or a rear portion of the seat cushion frame, and the hinge bracket is formed to be inclined downward. 8.The seat adjusting apparatus according to claim 1, wherein the third link member is inclined forward from the fixed bracket and connected to the seat cushion frame, and is formed to be in an inclined state with respect to a front portion even in a case where the seat cushion frame is raised. 9.A seat adjusting apparatus for a vehicle, comprising: a fixed bracket having a rear portion to which a back frame is rotatably connected; and a seat cushion frame provided at an upper side of the fixed bracket and inclined by a link mechanism, wherein the link mechanism includes: a first link member hinged to a front portion of the fixed bracket and supporting a front portion of the seat cushion frame, and connected to a driving unit to raise and lower the front portion of the seat cushion frame according to an operation of the driving unit; a second link member hinged to a rear portion of the fixed bracket and hinged to a middle portion or a rear portion of the seat cushion frame to guide a movement of the rear portion of the seat cushion frame; and a third link member hinged to the fixed bracket and the seat cushion frame and provided between the first link member and the second link member to determine an inclined position of the seat cushion frame when the seat cushion frame is raised, wherein the first link member, the second link member, and the third link member are provided to be spaced apart from each other along a length direction of the fixed bracket, the third link member is located at a central portion of the seat cushion frame and hinged to the fixed bracket and the seat cushion frame, and when the seat cushion frame is raised, the front portion of the seat cushion frame is raised and the rear portion of the seat cushion frame is lowered, such that a leg portion of an occupant is lifted and a hip point of the occupant is moved downward. 10.A seat adjusting apparatus for a vehicle, comprising: a fixed bracket having a rear portion to which a back frame is rotatably connected; and a seat cushion frame provided at an upper side of the fixed bracket and inclined by a link mechanism, wherein the link mechanism includes: a first link member hinged to a front portion of the fixed bracket and supporting a front portion of the seat cushion frame, and connected to a driving unit to raise and lower the front portion of the seat cushion frame according to an operation of the driving unit; a second link member hinged to a rear portion of the fixed bracket and hinged to a middle portion or a rear portion of the seat cushion frame to guide a movement of the rear portion of the seat cushion frame; and a third link member hinged to the fixed bracket and the seat cushion frame and provided between the first link member and the second link member to determine an inclined position of the seat cushion frame when the seat cushion frame is raised, wherein the first link member, the second link member, and the third link member are provided to be spaced apart from each other along a length direction of the fixed bracket, the third link member is located at a rear side of the seat cushion frame and hinged to the fixed bracket and the seat cushion frame, and when the seat cushion frame is raised, the front portion of the seat cushion frame is raised and the rear portion of the seat cushion frame is lowered, such that a leg portion of an occupant is lifted and a hip point of the occupant is moved downward. When the seat cushion frame is raised, the front portion of the seat cushion frame is tilted at a greater angle than the rear portion, such that a leg portion of an occupant is lifted, but a hip point of the occupant is maintained. 11.A seat adjusting apparatus for a vehicle, comprising: a fixed bracket having a rear portion to which a back frame is rotatably connected; and a seat cushion frame disposed on an upper side of the fixed bracket and tilted by a link mechanism, wherein the link mechanism includes: a first link member hinged to a front portion of the fixed bracket and supporting a front portion of the seat cushion frame, and connected to a driving unit to raise and lower the front portion of the seat cushion frame according to operation of the driving unit; a second link member hinged to a rear portion of the fixed bracket and to a middle portion or a rear portion of the seat cushion frame to guide movement of the rear portion of the seat cushion frame; and a third link member hinged to the fixed bracket and the seat cushion frame and disposed between the first link member and the second link member to determine a tilt position of the seat cushion frame when the seat cushion frame is raised, wherein the first link member, the second link member, and the third link member are disposed to be spaced apart from each other along a length direction of the fixed bracket, the third link member is located on a front portion side of the seat cushion frame and is hinged to the fixed bracket and the seat cushion frame, and when the seat cushion frame is raised, the rear portion of the seat cushion frame is tilted at a greater angle than the front portion, such that a hip point of an occupant is moved downwardly lower than a height at which a leg portion of the occupant is lifted.

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