Turning mechanism

Abstract

A turning mechanism comprises a holding structure, a first upper rack, a second upper rack, a first lower rack, a second lower rack, a slider, a first gear and a first gear. The first and second upper racks are connected to the holding structure. The first and second lower racks are respectively located below the first and second upper racks. The slider is connected with the first lower rack, the second lower rack and the holding structure. The first gear is driven to firstly engage and drive the first lower rack, and then to engage and drive the first upper rack. The second gear is driven to firstly engage and drive the second lower rack, and then to engage and drive the second upper rack. When the rotation speed of the first gear is higher than that of the second gear, the first lower rack drives the slider and at the same time the second lower rack moves relative to the slider, and the slider guides the action path of the holding structure, then the first and second upper racks jointly drive the holding structure to rotate.

Description

[Technical Field]

[0001] This disclosure relates to a steering mechanism, and more particularly to a steering mechanism applicable to automotive screens. [Previous Technology]

[0002] Generally speaking, most automotive screens are fixedly installed in front of the driver's side, which forces the driver to look at the screen at an angle, potentially leading to a poor viewing experience or glare. Even though some automotive screens may have adjustable viewing angles, they are often limited by the space constraints of the vehicle, resulting in screen rotation interference or the screen rotation angle not meeting requirements.

[0003] In view of the above, how to devise an improved steering mechanism suitable for automotive screens is the direction that practitioners in this technical field are striving to develop. [Summary of the Invention]

[0004] In view of prior art, this disclosure provides a steering mechanism applicable to automotive screens to solve the problem of screen rotation interference or screen rotation angle not meeting requirements.

[0005] This disclosure discloses a steering mechanism applicable to automotive screens. The steering mechanism includes a support structure, a first upper rack, a second upper rack, a first lower rack, a second lower rack, a moving member, a first gear, and a second gear. The support structure is connected to the automotive screen. The first and second upper racks are connected to the support structure. The first and second lower racks are located below the first and second upper racks, respectively. The moving member connects the first lower rack, the second lower rack, and the support structure. The first gear system is configured to be driven to first mesh and drive the first lower rack, and then mesh and drive the first upper rack. The second gear system is configured to be driven to first mesh and drive the second lower rack, and then mesh and drive the second upper rack. When the rotational speed of the first gear is higher than that of the second gear, the first lower rack drives the moving member, and simultaneously the second lower rack moves relative to the moving member. The moving member guides the actuation path of the support structure, and then the first and second upper racks jointly drive the support structure to rotate, causing the automotive screen to rotate accordingly to change its orientation.

[0006] In order to better understand the above and other aspects of this disclosure, specific embodiments are described below in detail with reference to the accompanying drawings.

Implementation Method

[0007] The various embodiments of this disclosure will be described in detail below, with reference to the accompanying drawings. In addition to these detailed descriptions, this disclosure can be widely implemented in other embodiments, and any easy substitutions, modifications, or equivalent changes to the described embodiments are included within the scope of this disclosure and are subject to the following patent claims. Furthermore, well-known steps or elements are not described in detail to avoid creating unnecessary limitations to this disclosure. And, unless otherwise stated, the same element symbols in different drawings can be considered corresponding elements.

[0008] Please refer to Figure 1, which shows a schematic diagram of a steering mechanism 100 and an automotive screen 10 applicable thereto according to an embodiment of the present disclosure.

[0009] The steering mechanism 100 is applicable to an automotive screen 10, which has a display surface 10S. The steering mechanism 100 disclosed herein allows the automotive screen 10 to change the facing direction of its display surface 10S, thereby enabling the user to clearly view the screen content from different viewing angles. The steering mechanism 100 may include a base 110, a support structure 120, a first upper rack 131, a second upper rack 132, a first lower rack 141, a second lower rack 142, a moving member 150, a first gear 161, a second gear 162, a first gear drive group 171, and a second gear drive group 172. The first upper rack 131, the second upper rack 132, the first lower rack 141, the second lower rack 142, the first gear 161, the second gear 162, the first gear drive group 171, and the second gear drive group 172 are all disposed within the base 110.

[0010] In this embodiment, the bracket structure 120 is T-shaped. The bracket structure 120 is movably connected to the base 110 and is adapted to connect the automotive screen 10. Specifically, the front end of the bracket structure 120 is fixed to the automotive screen 10, and the rear end of the bracket structure 120 is movably disposed within the base groove 110G of the base 110, that is, the bracket structure 120 is configured to move along the base groove 110G. Therefore, as the bracket structure 120 moves relative to the base 110, the automotive screen 10 fixed to the bracket structure 120 can move accordingly to change its position, such as by rotating or extending. The mechanism by which the steering mechanism 100 disclosed herein causes the automotive screen 10 to rotate and extend will be explained below.

[0011] Please refer further to Figures 2A, 2B, 2C, 3A, 3B, and 3C. Figures 2A, 2B, and 2C show top views of the steering mechanism 100 in operation. Figures 3A, 3B, and 3C show assembly diagrams of some components of the steering mechanism 100, corresponding to the operating states shown in Figures 2A, 2B, and 2C, respectively. It should be noted that some components are omitted in Figures 2A, 2B, 2C, 3A, 3B, and 3C to clearly show certain component details or to simplify the drawings.

[0012] The first upper rack 131 and the second upper rack 132 are symmetrically arranged on the left and right sides of the base 110. Specifically, the first upper rack 131 and the second upper rack 132 can each be mounted on the base 110 through two positioning pins, thereby being configured to be movable in a single orientation (corresponding to the Y-axis). The first upper rack 131 and the second upper rack 132 are connected to the support structure 120. The support structure 120 is movably disposed in the guide groove 131G of the first upper rack 131 and the guide groove 132G of the second upper rack 132, so that the support structure 120 can rotate relative to the first upper rack 131 and the second upper rack 132 without interference. The first lower rack 141 and the second lower rack 142 are symmetrically arranged on the left and right sides of the base 110. The first lower rack 141 is located below the first upper rack 131 (corresponding to the -Z-axis), and the second lower rack 142 is located below the second upper rack 132 (corresponding to the -Z-axis). The movable member 150 connects the first lower rack 141, the second lower rack 142, and the support structure 120. Specifically, the movable member 150 has a first U-shaped groove 151, a second U-shaped groove 152, and a triangular groove 153. The movable member 150 can be connected to the first lower rack 141 by providing a pin structure 141P that is located in the first U-shaped groove 151. The movable member 150 can be connected to the second lower rack 142 by providing a pin structure 142P that is located in the second U-shaped groove 152. The movable member 150 can be connected to the support structure 120 by providing a pin structure 120P that is located in the triangular groove 153.

[0013] Figure 2A omits the aforementioned automotive screen 10, and Figure 3A omits the aforementioned automotive screen 10, base 110, and first gear drive assembly 171. As shown in Figures 2A and 3A, this corresponds to the initial state of the steering mechanism 100. In the initial state, the first gear 161 meshes with the first lower rack 141, and the second gear 162 meshes with the second lower rack 142. Specifically, the first gear 161 meshes with the first lower rack 141 through its lower meshing area 161L, and the second gear 162 meshes with the second lower rack 142 through its lower meshing area 162L. The first gear 161 can be driven by the first gear drive assembly 171, and the second gear 162 can be driven by the second gear drive assembly 172. The first gear drive group 171 and the second gear drive group 172 may each be composed of, for example, an upper driving gear, a lower driving gear, a driven gear, a worm gear, and an electric motor, thereby controlling the rotational speed of the first gear 161 and the second gear 162. For details regarding the operation and configuration of the gear drive, please refer to patent application number TW113123397, which will not be elaborated here. In the initial state, the first gear 161 has not yet engaged the first upper rack 131, and the second gear 162 has not yet engaged the second upper rack 132. That is, at this time, the upper meshing area 161U of the first gear 161 is not engaged with the first upper rack 131, and the upper meshing area 162U of the second gear 162 is not engaged with the second upper rack 132. In the initial state, the pin structure 141P of the first lower rack 141 is symmetrically positioned in the first U-shaped groove 151, and the pin structure 142P of the second lower rack 142 is symmetrically positioned in the second U-shaped groove 152. Both are located at the intersection of the straight sections 151S and 152S of the first U-shaped groove 151 and the broken sections 151P and 152P of the second U-shaped groove 152 (shown in Figure 5). Furthermore, in the initial state, the pin structure 120P of the support structure 120 is located in the middle of the triangular groove 153. As shown in Figure 3A, in the initial state, the positions of the first lower rack 141 and the second lower rack 142 in the Y-axis are aligned with the same reference line L, meaning there is no positional difference between them in the Y-axis direction.

[0014] Figure 2B omits the aforementioned automotive screen 10, and Figure 3B omits the aforementioned automotive screen 10, base 110, and first gear drive assembly 171. As shown in Figures 2B and 3B, this corresponds to the intermediate operating state of the steering mechanism 100. The first gear drive assembly 171 drives the first gear 161, and the second gear drive assembly 172 drives the second gear 162. The first gear 161 can drive its meshing first lower rack 141, and the second gear 162 can drive its meshing second lower rack 142. When the rotational speed of the first gear 161 driven by the drive is different from that of the second gear 162 driven by the drive, the bracket structure 120 can be gradually rotated. In the timing stages shown in Figures 2A, 2B, and 2C, the example is that the rotational speed of the first gear 161 is higher than that of the second gear 162. When the rotational speed of the first gear 161 is higher than that of the second gear 162, the first lower rack 141 meshed with the first gear 161 moves forward (corresponding to the +Y axis), and the second lower rack 142 meshed with the second gear 162 moves forward (corresponding to the +Y axis) (but slower than the first gear 161). As a result, the pin structure 141P of the first lower rack 141 moves along the folded portion of the first U-shaped groove 151, thereby driving the moving member 150 to move to the left (corresponding to the -X axis), so that the pin structure 120P of the support structure 120 is relatively guided to the right section 153R of the triangular groove 153 (shown in Figure 5), while the pin structure 142P of the second lower rack 142 naturally moves along the straight section 152S of the second U-shaped groove 152 (shown in Figure 5). As shown in Figure 3B, during the intermediate operation state, due to the different rotational speeds of the first gear 161 and the second gear 162, the first lower rack 141 and the second lower rack 142 move at different speeds, resulting in a positional difference d in the Y-axis direction.

[0015] In the intermediate operating state, before the pin structure 120P of the support structure 120 is guided out of the right section of the triangular groove 153, the upper meshing area 161U of the first gear 161 is not engaged with the first upper rack 131, and the upper meshing area 162U of the second gear 162 is not engaged with the second upper rack 132. When the first lower rack 141 begins to push against the stop structure 131S of the first upper rack 131, and the second lower rack 142 subsequently begins to push against the stop structure 132S of the second upper rack 132, so that the first upper rack 131 and the second upper rack 132 are driven to begin to mesh with the first gear 161 and the second gear 162, and the pin structure 120P will gradually disengage from the moving member 150.

[0016] Figure 2C omits the aforementioned automotive screen 10, and Figure 3C omits the aforementioned automotive screen 10, base 110, and first gear drive assembly 171. As shown in Figures 2C and 3C, this corresponds to the later operating state of the steering mechanism 100. As the first gear 161 and the second gear 162 rotate continuously at different speeds, in the later operating state, the support structure 120 is guided to continuously move out of the triangular groove 153 and into the base groove 110G in the right section of the separating moving member 150. The first lower rack 141 and the second lower rack 142, driven by the meshing of the first gear 161 and the second gear 162 respectively, eventually move to the ends of the first U-shaped groove 151 and the second U-shaped groove 152 and are stopped. Because the first lower rack 141 and the second lower rack 142 are stopped, they can respectively push the stop structure 131S of the first upper rack 131 and the stop structure 132S of the second upper rack 132. Therefore, in the later operating state, the first upper rack 131 and the second upper rack 132 begin to mesh with the upper meshing area 161U of the first gear 161 and the upper meshing area 162U of the second gear 162, respectively. Since the rotational speed of the first gear 161 is higher than that of the second gear 162, the forward (corresponding to the +Y axis) speed of the first upper rack 131 is higher than that of the second upper rack 132, causing the bracket structure 120 to rotate counterclockwise about the Z axis. This indirectly causes the vehicle screen 10, which is fixed to the bracket structure 120, to rotate and change its orientation. As shown in Figure 3C, through the design of the tooth-cutting surface structure 141T of the first lower rack 141 and the side smooth surface 161S of the first gear 161, after the first lower rack 141 pushes the stop structure 131S of the first upper rack 131, the tooth-cutting surface structure 141T and the side smooth surface 161S avoid each other and will not come into contact. Therefore, the continuous rotation of the first gear 161 will not drive the first lower rack 141. It should be understood that the second lower rack 142 may also have a tooth-cutting surface structure, and the second gear 162 may also have a side smooth surface, to achieve the same effect that after the second lower rack 142 pushes the stop structure 132S of the second upper rack 132, the continuous rotation of the second gear 162 will not drive the second lower rack 142.

[0017] As shown in Figure 2C, the base groove 110G may include a first directional portion 110G1, a second directional portion 110G2, and a third directional portion 110G3 connected together. The third directional portion 110G3 is located between the first directional portion 110G1 and the second directional portion 110G2. The first directional portion 110G1, the second directional portion 110G2, and the third directional portion 110G3 are formed extending in different directions. In this embodiment, the first directional portion 110G1, the second directional portion 110G2, and the third directional portion 110G3 are in a mountain-shaped configuration. In this embodiment, the rotational speed of the first gear 161 is set to be higher than that of the second gear 162. Therefore, after the pin structure 120P of the support structure 120 is driven out of the triangular groove 153 of the moving member 150, the support structure 120 will enter the first directional portion 110G1 adjacent to the first gear 161. It should be understood that, conversely, if the rotational speed of the second gear 162 is set to be higher than that of the first gear 161, then after the pin structure 120P of the support structure 120 is driven out of the trident groove 153 of the moving member 150, the support structure 120 will enter the second directional portion 110G2 adjacent to the second gear 162, and the support structure 120 will rotate clockwise about the Z-axis.

[0018] As can be seen from the above description of Figures 2A, 2B, 2C, 3A, 3B and 3C, in the mechanism of the steering mechanism 100 for rotating the vehicle screen 10, the first gear 161 is configured to be driven to first mesh and drive the first lower rack 141, and then mesh and drive the first upper rack 131. The second gear 162 is configured to be driven to first mesh and drive the second lower rack 142, and then mesh and drive the second upper rack 132. When the rotational speed of the first gear 161 is higher than the rotational speed of the second gear 162, the first lower rack 141 can drive the moving member 150 and at the same time the second lower rack 142 moves relative to the moving member 150. The moving member 150 guides the actuation path of the bracket structure 120. Then the first upper rack 131 and the second upper rack 132 jointly drive the bracket structure 120 to rotate, so that the vehicle screen 10 fixed to the bracket structure 120 can rotate accordingly to change its orientation.

[0019] Please refer to Figures 4 and 5. Figure 4 shows a part drawing of the first gear 161 included in the steering mechanism 100, and Figure 5 shows a part drawing of the moving part 150 included in the steering mechanism 100.

[0020] As shown in Figure 4, the first gear 161 is a gear with an unconventional tooth surface structure design. As previously mentioned, the first gear 161 has an upper meshing area 161U and a lower meshing area 161L. The first lower rack 141 is configured to mesh with the lower meshing area 161L, while the first upper rack 131 is configured to mesh with the upper meshing area 161U. The number of teeth covered by the upper meshing area 161U is greater than the number of teeth covered by the lower meshing area 161L. Between the upper meshing area 161U and the lower meshing area 161L, the first gear 161 can be designed to have a non-meshing section 161N. The non-meshing section 161N is used to ensure that the first gear 161 does not mesh with the first upper rack 131 while driving the first lower rack 141 first. That is, the first upper rack 131 and the first lower rack 141 will not be driven by the first gear 161 at the same time, so that the first gear 161 is configured to be driven to mesh with and drive the first lower rack 141 first, and then mesh with and drive the first upper rack 131. It should be understood that the second gear 162 can also adopt the same but symmetrical tooth surface structure design as the first gear 161 shown in Figure 4, so as to achieve the same effect that the second gear 162 is configured to be driven to mesh with and drive the second lower rack 142 first, and then mesh with and drive the second upper rack 132.

[0021] As previously described, the movable member 150 has a first U-shaped groove 151, a second U-shaped groove 152, and a triangular groove 153. As shown in Figure 5, the first U-shaped groove 151 may include a straight section 151S and a broken section 151P, the second U-shaped groove 152 may include a straight section 152S and a broken section 152P, and the triangular groove 153 may include a left section 153L, a middle section 153M, and a right section 153R.

[0022] In the scenario described above, when the rotational speed of the first gear 161 is higher than that of the second gear 162, the corresponding support structure 120 will rotate counterclockwise as shown in Figure 2C. The pin structure 141P of the first lower rack 141 is initially located at the junction between the straight section 151S and the broken section 151P, and the pin structure 142P of the second lower rack 142 is located at the junction between the straight section 152S and the broken section 152P. Then, as the first gear 161 and the second gear 162 rotate, the pin structure 141P enters the broken section 151P until its end, and the pin structure 142P enters the straight section 152S until its end. Regarding the pin structure 120P of the support structure 120, the pin structure 120P is initially located in the middle section 153M. Then, as the moving member 150 is driven by the first lower rack 141 and the second lower rack 142, the pin structure 120P is guided into the right section 153R until it moves out of the moving member 150 and enters the first directional section 110G1 of the base groove 110G.

[0023] In another scenario, when the rotational speed of the second gear 162 is higher than that of the first gear 161, the corresponding support structure 120 will rotate clockwise in the opposite direction to that shown in Figure 2C. The pin structure 141P of the first lower rack 141 is initially located at the junction between the straight section 151S and the broken section 151P, and the pin structure 142P of the second lower rack 142 is located at the junction between the straight section 152S and the broken section 152P. Then, as the first gear 161 and the second gear 162 rotate, the pin structure 142P enters the broken section 152P until its end, and the pin structure 141P enters the straight section 151S until its end. Regarding the pin structure 120P of the support structure 120, the pin structure 120P is initially located in the middle section 153M. Then, as the moving member 150 is driven by the first lower rack 141 and the second lower rack 142, the pin structure 120P is guided into the left section 153L until it moves out of the moving member 150 and enters the second directional section 110G2 of the base groove 110G.

[0024] Please refer to Figures 6A and 6B, which show top views of the steering mechanism 100 during operation. The following description, together with Figures 2A and 6A and 6B, explains the extension mechanism of the steering mechanism 100.

[0025] When the steering mechanism 100 extends, it is initially in the initial state shown in Figure 2A. In the initial state, the first gear 161 meshes with the first lower rack 141, and the second gear 162 meshes with the second lower rack 142. Then, when the rotational speed of the first gear drive group 171 driving the first gear 161 is equal to the rotational speed of the second gear drive group 172 driving the second gear 162, as shown in Figures 6A and 6B, the pin structure 141P of the first lower rack 141 and the pin structure 142P of the second lower rack 142 are both located symmetrically in the U-shaped groove of the moving member 150 (located respectively in the broken line portion 151P of the first U-shaped groove 151 and the broken line portion 152P of the second U-shaped groove 152 mentioned above), thereby the first lower rack 141 and the second lower rack 142 can push the moving member 150 forward together (corresponding to the +Y axis). Subsequently, the first gear 161 and the second gear 162 mesh with the first upper rack 131 and the second upper rack 132, causing the first upper rack 131 and the second upper rack 132 to move forward and drive the bracket structure 120. The pin structure 120P of the bracket structure 120 moves linearly within the triangular groove 153 of the moving member 150 (specifically located in the middle section 153M of the triangular groove 153 mentioned above) and enters the third directional portion 110G3 of the base groove 110G. As a result, the automotive screen 10, which is fixed to the bracket structure 120, can extend forward.

[0026] As can be seen from the above description of Figures 2A, 6A and 6B, when the rotational speed of the first gear 161 is equal to the rotational speed of the second gear 162, the first lower rack 141 and the second lower rack 142 first jointly drive the moving member 150, the moving member 150 guides the actuation path of the bracket structure 120, and then the first upper rack 131 and the second upper rack 132 jointly drive the bracket structure 120 to move linearly, so that the automotive screen 10 moves accordingly to extend.

[0027] Furthermore, as shown in Figures 6A and 6B, the base 110 may be designed with a T-slot 110T, and the movable member 150 is configured to move along the T-slot 110T. In this embodiment, there are two T-slots 110T, and the movable member 150 may have two corresponding pin structures 150P. These two pin structures 150P are respectively disposed in the two T-slots 110T, so that the movable member 150 can be limited by the base 110. When the steering mechanism 100 rotates as described above, the movable member 150 moves left and right (corresponding to the X-axis) along the T-slot 110T; while when the steering mechanism 100 extends, the movable member 150 moves back and forth (corresponding to the Y-axis) along the T-slot 110T.

[0028] As described above, the steering mechanism for automotive screens disclosed in the above embodiments utilizes a combination of two sets of upper and lower racks and the engagement of two unconventional gears. When these two unconventional gears have a speed difference, the upper and lower racks can drive the support structure connected to the automotive screen, thereby allowing the automotive screen to rotate accordingly and change the orientation of the display surface. Furthermore, when these two unconventional gears do not have a speed difference, the upper and lower racks can drive the support structure connected to the automotive screen to move linearly, giving the automotive screen an extension mechanism.

[0029] Although this disclosure has been presented above with reference to embodiments, it is not intended to limit the scope of this disclosure. Those skilled in the art to which this disclosure pertains can make various modifications and refinements without departing from the spirit and scope of this disclosure. Therefore, the scope of protection of this disclosure shall be determined by the appended claims. [Simplified Explanation of the Diagram]

[0030] Figure 1 is a schematic diagram of a steering mechanism and an automotive screen applicable thereto according to an embodiment of the present disclosure; Figures 2A, 2B, and 2C are top views of a steering mechanism according to an embodiment of the present disclosure; Figures 3A, 3B, and 3C are assembly diagrams of some components of a steering mechanism according to an embodiment of the present disclosure; Figure 4 is a part drawing of a component included in a steering mechanism according to an embodiment of the present disclosure; Figure 5 is a part drawing of another component included in a steering mechanism according to an embodiment of the present disclosure; and Figures 6A and 6B are top views of a steering mechanism according to an embodiment of the present disclosure.

Claims

1. A steering mechanism for use with an automotive screen, the steering mechanism comprising: A bracket structure suitable for connecting the automotive screen; a first upper rack and a second upper rack connecting the bracket structure; A first lower rack and a second lower rack are respectively located below the first upper rack and the second upper rack; a movable member connects the first lower rack, the second lower rack, and the support structure, the movable member having a first U-shaped groove, a second U-shaped groove, and a triangular groove, wherein a pin structure of the first lower rack and a pin structure of the second lower rack are respectively located in the first U-shaped groove and the second U-shaped groove, and a pin structure of the support structure is located in the triangular groove; a first gear is configured to be driven to first mesh with and drive the first lower rack, and then mesh with and drive the first upper rack; and a second gear is configured to be driven to first mesh with and drive the second lower rack, and then mesh with and drive the second upper rack; When the rotational speed of the first gear is higher than that of the second gear, the first lower rack drives the moving member and the second lower rack moves relative to the moving member. The moving member guides the actuation path of the bracket structure. Then, the first upper rack and the second upper rack together drive the bracket structure to rotate, so that the automotive screen rotates accordingly to change its orientation.

2. The steering mechanism as described in claim 1, wherein when the rotational speed of the first gear is equal to the rotational speed of the second gear, the first lower rack and the second lower rack first jointly drive the moving member, the moving member guides the actuation path of the bracket structure, and then the first upper rack and the second upper rack jointly drive the bracket structure to move linearly, so that the vehicle screen moves accordingly to extend.

3. The steering mechanism as described in claim 1 or 2, further comprising: A base having a base groove, wherein the first upper rack, the second upper rack, the first lower rack, the second lower rack, the first gear and the second gear are disposed in the base, and the support structure is configured to move along the base groove.

4. The steering mechanism as described in claim 3, wherein the base has a T-slot and the moving member is configured to move along the T-slot.

5. The steering mechanism as claimed in claim 1 or 2, wherein the first gear has an upper engagement region and a lower engagement region, the first lower rack system is configured to engage the lower engagement region, and the first upper rack system is configured to engage the upper engagement region.

6. The steering mechanism as claimed in claim 5, wherein the number of teeth covered by the upper engagement zone is greater than the number of teeth covered by the lower engagement zone.

7. The steering mechanism as claimed in claim 5, wherein there is a non-engaging section between the upper engagement zone and the lower engagement zone.

8. The steering mechanism as described in claim 1 or 2, wherein the first lower rack has a toothed surface structure, the first gear has a smooth surface on one side, and when the first upper rack drives the support structure to rotate, the toothed surface structure and the smooth surface on one side avoid each other.

9. The steering mechanism as claimed in claim 1 or 2, wherein the first upper rack has a stop structure, the first gear is driven to first mesh with and drive the first lower rack until the first lower rack pushes against the stop structure, such that the first upper rack is driven to begin meshing with the first gear.

10. The steering mechanism as claimed in claim 1, wherein the first U-shaped groove and the second U-shaped groove each include a straight section and a broken section, wherein when the rotational speed of the first gear is higher than the rotational speed of the second gear, a pin structure of the first lower rack enters the broken section of the first U-shaped groove to drive the moving member, and a pin structure of the second lower rack moves along the straight section of the second U-shaped groove.

11. The steering mechanism as claimed in claim 1, wherein the triangular slot includes a left section, a middle section and a right section, and when the rotational speed of the first gear is higher than the rotational speed of the second gear, the moving member guides a pin structure of the support structure from the middle section into the right section.

12. The steering mechanism as claimed in claim 11, wherein when the rotational speed of the second gear is higher than that of the first gear, the moving member guides the pin structure of the support structure from the middle section into the left section.

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