CN111361674A

CN111361674A - Four-wheel steering mechanism

Info

Publication number: CN111361674A
Application number: CN202010334120.0A
Authority: CN
Inventors: 张孟仁
Original assignee: Taicang Jinquan Metal Product Co ltd
Current assignee: Taicang Jinquan Metal Product Co ltd
Priority date: 2020-04-24
Filing date: 2020-04-24
Publication date: 2020-07-03

Abstract

The invention relates to a four-wheel steering mechanism, which comprises a front wheel assembly, a rear wheel assembly and a linkage assembly, wherein the linkage assembly comprises a first traction piece and a second traction piece, the front end of the first traction piece is connected with the front wheel assembly, the rear end of the first traction piece is connected with the rear wheel assembly, the front end of the second traction piece is positioned on the left side, the front end of the second traction piece is positioned on the right side, the rear end of the first traction piece is positioned on the right side, and the rear end of the second traction piece is positioned on the left side. This four-wheel steering mechanism is through setting up the linkage subassembly, makes the front wheel subassembly can drive the rear wheel subassembly and turn to towards opposite direction simultaneously when turning to, has reduced the holistic turning radius of four-wheel steering mechanism like this greatly to make the operation of turning more nimble. The four-wheel steering mechanism can be applied to various types of vehicles for riding instead of walk, such as scooters, handicapped vehicles, knee vehicles for riding instead of walk and the like.

Description

Four-wheel steering mechanism

Technical Field

The invention relates to a four-wheel steering mechanism.

Background

In the prior art, various types of vehicles instead of walk, including scooter, handicapped vehicle, knee scooter, etc., are all front wheels to steer when turning, and then drive the vehicle body and the rear wheels to integrally steer towards the same direction. However, no linkage mechanism is arranged between the front wheels and the rear wheels, and particularly, when the vehicle is a four-wheel vehicle, namely two front wheels and two rear wheels, a certain distance exists between the two rear wheels, the conventional steering structure is adopted, so that the whole turning radius of the vehicle is large, and the turning is not flexible enough.

Disclosure of Invention

The invention aims to provide a four-wheel steering mechanism.

In order to achieve the purpose, the invention adopts the technical scheme that:

the invention provides a four-wheel steering mechanism, which comprises a connecting frame, a front wheel assembly, a rear wheel assembly and a linkage assembly,

the front wheel assembly comprises two front wheels which are arranged in bilateral symmetry, the front wheel assembly is arranged at the front part of the connecting frame in a bilateral rotation mode, and a rotation axis between the front wheel assembly and the connecting frame is defined as a front rotation axis;

the rear wheel assembly comprises two rear wheels which are arranged in bilateral symmetry, the rear wheel assembly is arranged at the rear part of the connecting frame in a bilateral rotation mode, and a rotation axis between the rear wheel assembly and the connecting piece is defined as a rear rotation axis;

the linkage assembly comprises a first traction piece, a second traction piece, a first traction piece and a second traction piece, wherein the front end of the first traction piece is directly or indirectly connected with the front wheel assembly, the rear end of the first traction piece is connected with the rear wheel assembly, the front end of the second traction piece is symmetrically arranged on the left side and the right side of the front rotating axis, the front end of the first traction piece is positioned on the left side of the front rotating axis, the front end of the second traction piece is positioned on the right side of the front rotating axis, the rear end of the first traction piece and the rear end of the second traction piece are symmetrically arranged on the left side and the right side of the rear rotating axis, the rear end of the first traction piece is positioned on the right side of the rear rotating axis, and the rear end of the second traction piece is positioned on the left side of the rear rotating axis.

Furthermore, the front wheel assembly comprises a front cross rod, the middle part of the front cross rod is connected with the front end part of the connecting frame in a left-right rotating mode, and the two front wheels are connected to the left end and the right end of the front cross rod respectively; the rear wheel assembly comprises a rear cross rod, the middle part of the rear cross rod is connected with the rear end part of the connecting frame in a left-right rotating mode, and the two rear wheels are connected to the left end and the right end of the rear cross rod respectively.

Furthermore, the middle part of the front cross rod is fixedly connected with a handle rod and is connected with the connecting frame through the handle rod in a left-right rotating mode, and the front end of the first traction piece and the front end of the second traction piece are respectively connected with the front cross rod or the handle rod.

Furthermore, the rear end of the first traction piece and the rear end of the second traction piece are respectively connected with the rear cross bar.

Further, the first traction member and the second traction member are flexible members, and brake cables are preferably adopted to ensure sufficient strength and service life.

Furthermore, a first relative position and a second relative position which form an acute angle are arranged between the connecting frame and the rear wheel component, and the second relative position includes a left-turning condition and a right-turning condition, wherein the opening of the acute angle faces to the left during the left-turning, and the opening of the acute angle faces to the right during the right-turning. An elastic piece which can enable the connecting frame and the rear wheel assembly to return to the first relative position from the second relative position is arranged between the connecting frame and the rear wheel assembly. The elastic parts are preferably two and are symmetrically arranged on the left side and the right side of the connecting frame, so that the stress of the rear wheel assembly is balanced. When normally advancing, the elastic component can make the rear wheel subassembly keep mutually perpendicular with the link to the supplementary user keeps the direction of advance, and when accomplishing to turn to the back and resume advancing, the elastic component can make the rear wheel subassembly reply to the position perpendicular with the link more fast, makes user's operation more laborsaving, keeps balanced when advancing more easily. The elastic member is preferably a drum type spring to secure a tension compression durability.

Furthermore, front connecting pieces are symmetrically arranged on the left side and the right side of the front part of the connecting frame, and the first traction piece and the second traction piece are respectively slidably arranged in the front connecting pieces on the left side and the right side; the left side and the right side of the rear part of the connecting frame are symmetrically provided with rear connecting pieces, and the second traction piece and the first traction piece are respectively and slidably arranged in the rear connecting pieces on the left side and the right side; the parts of the first traction piece and the second traction piece between the front connecting piece and the rear connecting piece are arranged in a mutually crossed mode.

Furthermore, the distance from the front end of the first traction piece to the front end of the second traction piece, the distance between the front connecting pieces on the left side and the right side, the distance between the rear connecting pieces on the left side and the right side, and the distance from the rear end of the first traction piece to the rear end of the second traction piece are all equal.

Furthermore, an elastic part is arranged between each rear connecting part and the rear wheel assembly, and the two elastic parts are symmetrically arranged on the left side and the right side of the connecting frame.

Furthermore, the first traction piece and the second traction piece are respectively arranged in the two elastic pieces in a penetrating mode, so that the balance of force among the first traction piece, the second traction piece and the rear wheel assembly is guaranteed, and the structure is compact.

Furthermore, an operating part is arranged on the upper part of the handle rod, and the operating part enables the handle rod to drive the front wheel component to rotate left and right together by operating the operating part.

Due to the application of the technical scheme, the four-wheel steering mechanism enables the front wheel assembly to drive the rear wheel assembly to steer towards the opposite direction when steering by arranging the linkage assembly, so that the integral turning radius of the mechanism is greatly reduced, and the turning operation is more flexible. The four-wheel steering mechanism can be applied to various types of vehicles for riding instead of walk, such as scooters, handicapped vehicles, knee vehicles for riding instead of walk and the like.

Drawings

Some specific embodiments of the invention will be described in detail hereinafter, by way of illustration and not limitation, with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. In the drawings:

FIG. 1 is a schematic side view of a four-wheel steering mechanism of the present invention, which is used on a scooter;

FIG. 2 is a schematic top view of the four-wheel steering mechanism of the embodiment of FIG. 1, illustrating the four-wheel steering mechanism in a straight-ahead position;

FIG. 3 is a schematic view of the structure shown in FIG. 2 when rotated to the left;

FIG. 4 is a schematic view of the structure shown in FIG. 2 when turning to the right;

FIG. 5 is a schematic top view of the scooter of FIG. 1, with the handlebar assembly omitted;

FIG. 6 is a schematic view of a connection structure between a pedal and a frame of the scooter of FIG. 1, shown from a front-to-rear perspective, wherein the pedal is in a horizontal position;

FIG. 7 is a schematic view of the structure of FIG. 6 when tilted to the left;

FIG. 8 is a schematic view of the structure when tilted to the right on the basis of FIG. 6;

FIG. 9 is a side view of the frame of the scooter shown in FIG.;

FIG. 10 is a side elevational view of another embodiment of the four wheel steering mechanism of the present invention as applied to a knee walker;

fig. 11 is a schematic top view of the four-wheel steering mechanism of the embodiment of fig. 10, showing the four-wheel steering mechanism in a straight-ahead position.

Wherein the reference numerals are as follows:

1. a pedal assembly; 11. a connecting frame; 111. a bottom bar; 112. a front link; 113. a rear connecting rod; 114. a sleeve; 12. a pedal; 13. a support; 131. an upper base; 132. a lower base;

2. a handlebar assembly; 21. a handle bar; 22. a handle; 23. a connecting member;

3. a front wheel assembly; 31. a front wheel; 32. a front cross bar;

4. a rear wheel assembly; 41. a rear wheel; 42. a rear cross bar;

5. a linkage assembly; 51. a first traction member; 52. a second traction member; 53. a front connector; 54. a rear connector; 55. an elastic member;

6. a seat.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "front", "rear", "left" and "right" are defined according to the normal usage habit of the four-wheel steering mechanism, the normal forward direction of the four-wheel steering mechanism is "front", whereas the backward direction is "rear", and the left and right sides are respectively "left" and "right" with reference to the front-rear direction. The terms indicating orientation or positional relationship referred to in the present invention are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Example one

Referring to fig. 1 to 9, the four-wheel steering mechanism of the present embodiment includes a connecting frame 11, a front wheel assembly 3, a rear wheel assembly 4, and a linkage assembly 5.

The link 11 is arranged in the front-rear direction.

The front wheel assembly 3 includes two front wheels 31 disposed bilaterally symmetrically, the front wheel assembly 3 is disposed at the front portion of the connecting frame 11 to be rotatable left and right, and a rotation axis between the front wheel assembly 3 and the connecting member 11 is defined as a front rotation axis.

The rear wheel assembly 4 includes two rear wheels 41 disposed bilaterally symmetrically, the rear wheel assembly 4 is disposed at the rear of the link frame 11 to be rotatable left and right, and a rotation axis between the rear wheel assembly 4 and the link frame 11 is defined as a rear rotation axis.

The linkage assembly 5 is arranged between the front wheel assembly 3 and the rear wheel assembly 4, the linkage assembly 5 comprises a first traction piece 51 of which the front end is directly or indirectly connected with the front wheel assembly 3 and the rear end is connected with the rear wheel assembly 4, a second traction piece 52 of which the front end is directly or indirectly connected with the front wheel assembly 3 and the rear end is connected with the rear wheel assembly 4, the front end of the first traction piece 51 and the front end of the second traction piece 52 are symmetrically arranged at the left side and the right side of the front rotation axis, and the front end of the first pulling member 51 is positioned at the left side of the front rotation axis, the front end of the second pulling member 52 is positioned at the right side of the front rotation axis, the rear end of the first pulling member 51 and the rear end of the second pulling member 52 are symmetrically arranged at the left and right sides of the rear rotation axis, and the rear end of the first pulling member 51 is located at the right side of the rear rotational axis and the rear end of the second pulling member 52 is located at the left side of the rear rotational axis. Since the first traction member 51 and the second traction member 52 are arranged in a crossed manner, when the front wheel assembly 3 turns, the first traction member 51 and the second traction member 52 drive the rear wheel assembly 4 to turn in opposite directions, specifically, when a user rides and the front wheel assembly 3 turns to the left, the second traction member 52 moves forward relative to the connecting frame 11, the first traction member 51 moves backward relative to the connecting frame 11, so as to drive the rear wheel assembly 4 to turn to the right, when the front wheel assembly 3 turns to the right, the first traction member 51 moves forward relative to the connecting frame 11, and the second traction member 52 moves backward relative to the connecting frame 11, so as to drive the rear wheel assembly 4 to turn to the left.

In this embodiment, the first pulling member 51 and the second pulling member 52 are both flexible members, and preferably adopt brake cables to ensure sufficient strength and service life.

The first pulling member 51 and the second pulling member 52 in this embodiment are disposed substantially on the same plane, so that the overall structure is more compact. Since the first pulling member 51 and the second pulling member 52 are offset up and down at the intersection, they cannot be exactly on the same plane, so that they are said to be "substantially" on the same plane.

The connecting frame 11 and the rear wheel assembly 4 have a first relative position (as shown in fig. 2, in which the four-wheel steering mechanism is in a normal forward state) and a second relative position with an acute angle therebetween, which include both left-turn and right-turn conditions of the four-wheel steering mechanism, wherein the opening of the acute angle faces left (as shown in fig. 3) during left-turn and right-turn (as shown in fig. 4). An elastic member 55 is arranged between the connecting frame 11 and the rear wheel assembly 4 and can enable the connecting frame and the rear wheel assembly to return to the first relative position from the second relative position. The elastic members 55 are preferably provided in two and symmetrically at the left and right sides of the connecting frame 11 to balance the force applied to the rear wheel assembly 4. When the user finishes steering and resumes moving forward, the elastic member 55 can make the rear wheel assembly 4 return to the position perpendicular to the connecting frame 11 more quickly, so that the user's operation is more labor-saving and the user can keep balance more easily. In addition, the elastic member 55 can also keep the tension of the flexible first traction member 51 and the flexible second traction member 52 during steering without loosing. The elastic member 55 is preferably a drum type spring to secure the tension compression durability. In this embodiment, the first pulling member 51 and the second pulling member 52 are respectively inserted into the two elastic members 55, which is more beneficial to ensure the balance of forces among the first pulling member 51, the second pulling member 52 and the rear wheel assembly 4, and at the same time, make the structure more compact.

More specifically, the front wheel assembly 3 includes a front cross bar 32 having a middle portion connected to the front end portion of the connecting frame 11 to rotate left and right, and two front wheels 31 connected to left and right ends of the front cross bar 32, respectively; the rear wheel assembly 4 includes a rear cross bar 42 having a middle portion rotatably connected to the rear end portion of the link 11 in the left and right directions, and two rear wheels 41 are respectively connected to the left and right ends of the rear cross bar 42. The front rail 32 and the rear rail 42 in this embodiment are straight bars. The front ends of the first pulling member 51 and the second pulling member 52 can be connected to the front wheel assembly 3 in the present embodiment (as will be described in detail below), and the front ends of the first pulling member 51 and the second pulling member 52 can be connected to the front cross bar 32 respectively; the rear ends of the first pulling member 51 and the second pulling member 52 are connected to the rear cross bar 42 in the rear wheel assembly 4, respectively.

In the embodiment shown in fig. 1 to 4, the handle bar 21 is fixedly connected to the middle of the front cross bar 32 and is connected to the connecting frame 11 through the handle bar 21 in a left-right rotating manner, the front end of the first traction member 51 and the front end of the second traction member 52 are both connected to the handle bar 21, specifically, the connecting member 23 is fixedly connected to the handle bar 21, the position of the connecting member 23 is located below the axle of the front wheel 31, and the connecting member 23 and the handle bar 21 are fixed by welding for ensuring strength. The front end of the first pulling member 51 and the front end of the second pulling member 52 are connected to the left and right sides of the link 23, respectively. Further, the front cross bar 32 is connected to the bottom of the handle bar 21, and an operation member for operating the front cross bar 21 to rotate the front wheel assembly 3 together with the handle bar 21 is provided on the upper portion of the handle bar 21.

In a more preferred embodiment, as shown in fig. 2 to 4, front connection members 53 are symmetrically provided on left and right sides of a front portion of the connection frame 11, and the first drawing member 51 and the second drawing member 52 are slidably inserted into the left and right front connection members 53, respectively; rear connecting pieces 54 are symmetrically arranged on the left side and the right side of the rear part of the connecting frame 11, and the second traction piece 52 and the first traction piece 51 are respectively slidably arranged in the rear connecting pieces 54 on the left side and the right side; the portions of the first drawing member 51 and the second drawing member 52 between the front coupling member 53 and the rear coupling member 54 are disposed to cross each other.

Further, the distance from the front end of the first pulling member 51 to the front end of the second pulling member 52, the distance between the front connecting members 53 on the left and right sides, the distance between the rear connecting members 54 on the left and right sides, and the distance from the rear end of the first pulling member 51 to the rear end of the second pulling member 52 are all equal, that is, in normal forward travel (when steering is not performed, as in the state shown in fig. 2), the portions of the first and

second traction members

51 and 52 between the link member 23 and the front link member 53 (hereinafter referred to as front parallel portions) are arranged in parallel, the portions of the first and

second traction members

51 and 52 between the rear wheel assembly 4 and the rear link member 54 (hereinafter referred to as rear parallel portions) are arranged in parallel, and, the distance between the front parallel portions of the first drawing member 51 and the second drawing member 52 is equal to the distance between the rear parallel portions of the first drawing member 51 and the second drawing member 52.

The above-mentioned elastic member 55 is respectively provided between each rear link 54 and the rear cross bar 42.

The four-wheel steering mechanism in this embodiment is applied to a scooter. The scooter still includes footboard subassembly 1, pivot connection in the handle pole subassembly 2 of the front end of footboard subassembly 1. The pedal assembly 1 comprises the above-mentioned connecting frame 11 and the pedal 12 rotatably connected above the connecting frame 11. The handle bar assembly 2 includes the above-mentioned handle bar 21 and a handle 22 connected to an upper end portion of the handle bar 21, and the handle 22 is an operating member as mentioned above.

In a more preferred embodiment, the pedal 12 is rotatably connected to the connecting frame 11 with the rotation axis extending in the front-rear direction, and the linkage assembly 5 is disposed below the pedal 12. When the scooter is running, the pedals 12 are inclined left and right, and the handle bar assembly 2 is turned left and right, so that the friction force generated between the front wheel 31 and the rear wheel 41 and the ground can generate forward assisting force, the scooter can run forwards in a snake-shaped track, and a user does not need to step backwards ceaselessly. By using the scooter in the mode, the whole body can be exercised, the coordination and the balance ability of the whole body are trained, and the exercise pleasure is increased. More specifically, pedal 12 is rotatably connected to connecting frame 11 through bracket 13, bracket 13 includes an upper base 131 fixedly connected to the lower side of pedal 12 and a lower base 132 fixedly connected to connecting frame 11, and upper base 131 is rotatably connected to lower base 132. In a more preferred embodiment, a limiting structure is disposed between the upper base 131 and the lower base 132 to control the mutual rotation angle between them within a certain range, so as to prevent the pedal 12 and the connecting frame 11 from rotating too much when the user rides, which results in the user losing balance. In the present embodiment, the rotation angle is set in the range of 10 ° each on the left and right. The specific structure of the limiting structure is not limited, and in actual implementation, the structure in the prior art can be selected according to the situation. In order to ensure the stability of the pedal 12 and the connecting frame 11 during relative rotation, at least two brackets 13 are arranged between the pedal 12 and the connecting frame 11, and the at least two brackets 13 are distributed along the front-back direction. In the present embodiment shown in fig. 1 and 5, two brackets 13 are symmetrically arranged in front and back. In this embodiment, the connecting frame 11 includes a bottom bar 111, a front link 112 and a rear link 113, as shown in fig. 1 and 5. The bottom rod 111 is horizontally arranged in the front-rear direction, the pedal 12 is rotatably connected to the bottom rod 111, that is, the lower base 132 of the bracket 13 is connected to the bottom rod 111, and the pedal 12 is located right above the bottom rod 111, referring to fig. 1; the connecting rod 112 extends forwards and upwards from the front end of the bottom rod 111, in this embodiment, the front connecting rod 112 is in an arc shape which is arched upwards, the radian of the front connecting rod 112 is matched with the shape and size of the front wheel 31 in the front wheel assembly 3, the handle rod assembly 2 is pivotally connected with the front end of the front connecting rod 112, specifically, the front end of the front connecting rod 112 is connected with the sleeve 114, and the handle rod assembly 2 is pivotally connected with the sleeve 114; the rear link 113 extends rearward and upward from the rear end of the base bar 111, the rear link 113 in this embodiment is a straight bar, and the rear wheel assembly 4 is connected to the rear end of the rear link 113.

In a more preferred embodiment, the handle bar 21 may be provided as a telescopic rod structure in order to accommodate users of different heights.

Example two

Referring to fig. 10 and 11, the four-wheel steering mechanism of the present embodiment is applied to a knee walker. Besides the four-wheel steering mechanism, the knee scooter also comprises a handlebar rod assembly 2 and a seat 6, wherein the seat 6 is connected with a connecting frame 11. The handle bar assembly 2 of this embodiment is similar to that of the first embodiment, and will not be described herein.

In order to adapt to the structure of the knee walker, the connecting frame 11 of the present embodiment is formed in an upwardly arched shape, as shown in fig. 10, so that the seat 6 has a sufficient height from the ground, and preferably, a mechanism for adjusting the height of the seat 6 is provided between the seat 6 and the connecting frame 11. The first pulling member 51 and the second pulling member 52 are located below the seat 6 and are arranged substantially along the curved course of the connecting frame 11, and do not substantially extend beyond the connecting frame 11 in the up-and-down direction, so as to make the structure more compact and visually more simple and beautiful.

The front cross bar 32 in this embodiment is a forward arched bar, as shown in fig. 11.

In addition, as shown in fig. 11, in the present embodiment, the distance between the front connecting members 53 on the left and right sides, the distance between the rear connecting members 54 on the left and right sides, and the distance from the rear end of the first pulling member 51 to the rear end of the second pulling member 52 are all equal, but due to structural limitations, the distance from the front end of the first pulling member 51 to the front end of the second pulling member 52 is not equal to the above distance, but is not different by a large amount, so as to ensure that no excessive friction force is generated between the pulling member and the front connecting members 53.

The four-wheel steering mechanism in the embodiment enables the front wheel assembly to drive the rear wheel assembly to steer towards the opposite direction simultaneously when steering by arranging the linkage assembly, so that the integral turning radius of the mechanism is greatly reduced, and the turning operation is more flexible. The four-wheel steering mechanism can be applied to various types of vehicles for riding instead of walk, such as scooters, handicapped vehicles, knee vehicles for riding instead of walk and the like.

The above embodiments are merely illustrative of the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the content of the present invention and implement the invention, and not to limit the scope of the invention, and all equivalent changes or modifications made according to the spirit of the present invention should be covered by the scope of the present invention.

Claims

1. A four-wheel steering mechanism is characterized in that: comprises that

A connecting frame (11),

a front wheel assembly (3), wherein the front wheel assembly (3) comprises two front wheels (31) which are arranged in bilateral symmetry, the front wheel assembly (3) is arranged at the front part of the connecting frame (11) in a bilateral rotation mode, and a rotation axis between the front wheel assembly (3) and the connecting piece (11) is defined as a front rotation axis;

a rear wheel assembly (4), the rear wheel assembly (4) comprising two rear wheels (41) arranged in bilateral symmetry, the rear wheel assembly (4) being arranged at the rear part of the connecting frame (11) in a bilateral rotation manner, and a rotation axis between the rear wheel assembly (4) and the connecting frame (11) being defined as a rear rotation axis;

a linkage assembly (5), the linkage assembly (5) comprising a first traction member (51) having a front end connected to the front wheel assembly (3) directly or indirectly and a rear end connected to the rear wheel assembly (4), a second traction member (52) having a front end connected to the front wheel assembly (3) directly or indirectly and a rear end connected to the rear wheel assembly (4), the front end of the first traction member (51) and the front end of the second traction member (52) being symmetrically disposed at left and right sides of the front rotation axis, the front end of the first traction member (51) being located at left side of the front rotation axis, the front end of the second traction member (52) being located at right side of the front rotation axis, the rear end of the first traction member (51) and the rear end of the second traction member (52) being symmetrically disposed at left and right sides of the rear rotation axis, and the rear end of the first traction member (51) being located at right side of the rear rotation axis, the rear end of the second pulling member (52) is located to the left of the rear rotational axis.

2. The four-wheel steering mechanism according to claim 1, wherein: the front wheel assembly (3) comprises a front cross rod (32) of which the middle part is connected with the front end part of the connecting frame (11) in a left-right rotating manner, and the two front wheels (31) are respectively connected to the left end and the right end of the front cross rod (32); the rear wheel assembly (4) comprises a rear cross rod (42) of which the middle part is connected with the rear end part of the connecting frame (11) in a left-right rotating mode, and the two rear wheels (41) are respectively connected to the left end and the right end of the rear cross rod (42).

3. The four-wheel steering mechanism according to claim 2, wherein: the middle part of the front cross rod (32) is fixedly connected with a handle rod (21) and is connected with the connecting frame (11) through the handle rod (21) in a left-right rotating mode, and the front end of the first traction piece (51) and the front end of the second traction piece (52) are respectively connected with the front cross rod (32) or the handle rod (21).

4. The four-wheel steering mechanism according to claim 2, wherein: the rear end of the first traction piece (51) and the rear end of the second traction piece (52) are respectively connected with the rear cross bar (42).

5. The four-wheel steering mechanism according to claim 1, wherein: the first traction member (51) and the second traction member (52) are both flexible members.

6. The four-wheel steering mechanism according to claim 1, wherein: the connecting frame (11) and the rear wheel assembly (4) are mutually perpendicular to each other at a first relative position and at a second relative position with an acute included angle, and an elastic piece (55) capable of enabling the connecting frame (11) and the rear wheel assembly (4) to return to the first relative position from the second relative position is arranged between the connecting frame (11) and the rear wheel assembly.

7. The four-wheel steering mechanism according to claim 1, wherein: front connecting pieces (53) are symmetrically arranged on the left side and the right side of the front part of the connecting frame (11), and the first traction piece (51) and the second traction piece (52) are respectively slidably arranged in the front connecting pieces (53) on the left side and the right side; rear connecting pieces (54) are symmetrically arranged on the left side and the right side of the rear part of the connecting frame (11), and the second traction piece (52) and the first traction piece (51) are respectively slidably arranged in the rear connecting pieces (54) on the left side and the right side in a penetrating manner; the portions of the first pulling member (51) and the second pulling member (52) between the front connecting member (53) and the rear connecting member (54) are arranged to cross each other.

8. The four-wheel steering mechanism according to claim 7, wherein: the distance from the front end of the first traction piece (51) to the front end of the second traction piece (52), the distance between the front connecting pieces (53) on the left side and the right side, the distance between the rear connecting pieces (54) on the left side and the right side, and the distance from the rear end of the first traction piece (51) to the rear end of the second traction piece (52) are all equal.

9. The four-wheel steering mechanism according to claim 7, wherein: an elastic part (55) is arranged between each rear connecting part (54) and the rear wheel component (4).

10. The four-wheel steering mechanism according to claim 3, wherein: the upper part of the handle rod (21) is provided with an operating component which enables the handle rod (21) to drive the front wheel component (3) to rotate left and right together by operating the operating component.